JP6219254B2 - Variable speed drive mechanism for internal combustion engine - Google Patents

Description

  The present invention provides an internal combustion engine in which a shift fork guided in a lead groove of a shift drum moves in an axial direction shifts a transmission by moving a shifter gear in an axial direction and engaging with a free gear of a required shift stage. The present invention relates to a transmission drive mechanism for an engine transmission.

  Patent Document 1 discloses a dual-structure main shaft composed of inner and outer shafts, a countershaft arranged in parallel with the main shaft, a drive gear corresponding to an odd-numbered shift stage supported by the inner shaft, A drive gear corresponding to an even speed stage supported by a shaft, a first clutch for an odd speed stage connected to an inner shaft, a second clutch for an even speed stage connected to an outer shaft, and a first clutch And a second clutch, a so-called DCT (Dual Clutch Transmission) type transmission comprising a clutch outer for supplying rotational driving force from a crankshaft to the second clutch, and a driven gear and a driven gear supported by the meshing countershaft. Is disclosed.

  A DCT type transmission as disclosed in Patent Document 1 has a predetermined gear position by engaging and disengaging dog teeth respectively provided in a slide gear (shifter gear) and a free gear included in a drive gear and a driven gear. Shifting to is done. At this time, when hydraulic pressure is supplied to one clutch and one main shaft is rotating, a small hydraulic pressure is supplied to the other clutch so that the clutch is not in a connected state (applying preload). This main shaft also rotates at approximately the same speed as one of the main shafts. This is because the free gear is always rotated while the vehicle is running, and the free gear and the shifter gear corresponding to this are rotated at different rotational speeds using the gear ratio, so that the free gear and the shifter gear are rotated. This is done for the purpose of giving a differential rotation to the number of rotations and securing an opportunity for engagement of the dog teeth.

JP 2009-108932 A

However, if a differential rotation is given to the rotation speed of the free gear of a predetermined gear stage and the shifter gear corresponding thereto, the dog teeth provided on the shifter gear and the dog teeth provided on the free gear are shifted during the upshifting operation. When engaged, dog teeth may collide with each other in accordance with the magnitude of the differential rotation, and a hitting sound may be generated. At this time, since the differential rotation increases in accordance with the engine speed, the above-described striking operation is performed during a shift-up operation of a transmission that performs a shift while accelerating, particularly during a shift-up operation at a low gear stage with a large gear ratio. There was a high possibility of sound.
Further, in the case of a shift operation from the neutral position to the first speed position at the time of starting the vehicle, the countershaft is not rotating, and the shifter gear that is not rotating on the dog gear of the free gear for the first speed that is idling. Since the dog teeth are engaged, the hitting sound described above may occur.

  Further, even in a so-called single clutch type transmission having a single clutch, the countershaft is not rotating during the shift operation from the neutral to the first speed, as in the case of the DCT type transmission, and thus is idling. When the dog teeth are engaged between the free gear and the non-rotating shifter gear, a hitting sound may occur.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, to reduce the hitting sound during a shift-up operation in a DCT transmission, and to shift up from neutral to first gear in a single clutch transmission. It is to reduce the hitting sound during operation.

In order to solve the above-described problem, a variable speed drive mechanism for an internal combustion engine according to the present invention includes:
A main shaft that supports a plurality of drive gears, a hydraulic clutch that is connected to the main shaft and intermittently transmits the rotational driving force from the crankshaft by hydraulic pressure, and a plurality of driven gears that mesh with the drive gear are supported. A constant-mesh transmission having a counter shaft,
A shift drum that is rotated during shifting of the transmission and has a plurality of lead grooves on its outer circumferential surface in the radial direction , a shift fork shaft that is arranged in parallel with the shift drum, and a plurality of the shift drums A change mechanism that includes a plurality of shift forks that are respectively engaged with the lead grooves and guided in the axial direction of the shift fork shaft,
Each of the drive gear and the driven gear rotates integrally with a shaft to be supported and is movable in the axial direction, and each of the shifter gears has shifter-side dog teeth formed on a surface orthogonal to the axial direction. A free gear that is rotatable relative to the supported shaft and is fixed so as not to move in the axial direction, and has a free side dog tooth that is detachably opposed to the shifter side dog tooth;
The shift fork is locked in a locking groove formed in the shifter gear,
The shift fork, which is guided in the lead groove and moves in the axial direction by the rotation of the shift drum, moves the shifter gear to engage the shifter side dog teeth with the corresponding free side dog teeth, thereby changing the speed change. In a speed change drive mechanism of an internal combustion engine for shifting the machine,
Of the lead grooves, a wall surface of the main side lead groove engaged with a lead groove side end of the shift fork for moving the shifter gear supported by the main shaft extends from the wall surface to the main side lead groove. Protrusions projecting inward are provided,
During the shift-up operation of the transmission, the projecting portion presses the end portion on the lead groove side of the shift fork guided by the main side lead groove, so that the shifter side of the shifter gear of the next shift stage Before the dog teeth engage with the free-side dog teeth of the corresponding free gear, the shift fork guided by the main-side lead groove is normally supported by the main shaft by the protrusion. The rotation of the main shaft is decelerated by being temporarily pressed into the locking groove of the shifter gear.

  According to this configuration, during the shift-up operation of the transmission, before the shifter side dog teeth of the shifter gear and the free side dog teeth of the free gear are engaged, the shift fork is formed by the protrusion provided in the main side lead groove. The end portion on the lead groove side is pressed toward the protruding direction of the protrusion, and the shift fork is pressed against the locking groove of the shifter gear supported by the main shaft more than usual.

The free gear corresponding to the next shift stage supported by the counter shaft is rotated at a higher speed than the shifter gear supported by the counter shaft by being rotated by the drive gear supported by the main shaft. When the shift fork is pressed into the locking groove of the shifter gear supported by the main shaft in this state, the main shaft rotating together with the shifter gear and the shifter gear is rotated by the frictional force generated between the locking groove and the shift fork. The rotation of the free gear supported by the counter shaft that is decelerated and rotated by the shifter gear supported by the main shaft is also decelerated.
In addition, the free gear corresponding to the next gear stage supported by the main shaft rotates at a lower speed than the shifter gear supported by the same main shaft depending on the gear ratio. Is pressed, the shifter gear supported by the main shaft and the rotation of the main shaft are decelerated.

  In other words, by decelerating the rotation of the main shaft during the upshifting operation, the rotation on the faster side of the shifter gear or free gear corresponding to the next gear stage is decelerated, thereby reducing the differential rotation between the shifter gear and the free gear. In addition, it is possible to reduce the hitting sound when the shifter side dog teeth of the shifter gear engage with the free side dog teeth of the free gear.

In the above-described shift drive mechanism for an internal combustion engine according to the present invention,
The main shaft is composed of an odd-numbered main shaft and an even-numbered main shaft,
The hydraulic clutch includes an odd-numbered hydraulic clutch coupled to the odd-numbered main shaft, an even-numbered hydraulic clutch coupled to the even-numbered main shaft, the odd-numbered hydraulic clutch, and the even-numbered hydraulic clutch. A clutch outer for supplying rotational driving force from the shaft,
The drive gear includes an odd-numbered stage drive gear supported by the odd-numbered stage main shaft, and an even-numbered stage drive gear supported by the even-numbered stage main shaft,
The shifter gear includes a drive shifter gear including an odd-numbered stage drive shifter gear disposed in the odd-numbered stage drive gear, an even-numbered stage shifter gear disposed in the even-numbered stage drive gear, and a driven shifter gear disposed in the driven gear. Have
The shift fork includes an odd-numbered stage main-side shift fork that is locked in the locking groove of the odd-numbered stage drive gear and an even-numbered stage main-side shift fork locked in the locking groove of the even-numbered stage drive gear. A main-side shift fork, and a counter-side shift fork locked in the locking groove of the driven gear,
The fork side end of the odd-numbered main shift fork is locked in the locking groove of the odd-numbered drive shifter gear,
The fork side end of the even-numbered main shift fork is locked in the locking groove of the even-numbered drive shifter gear,
The main-side lead groove is engaged with an odd-numbered main-side lead groove that is engaged with an end portion of the odd-numbered main-side shift fork and an end portion of the even-numbered main-side shift fork. Even-numbered main-side lead grooves
At least one of the odd-numbered-stage main-side lead groove and the even-numbered-stage main-side lead groove is a protrusion-positioned lead groove provided with the protrusion,
During the shift-up operation of the transmission, the protrusion presses the lead groove side end of the main shift fork engaged with the protrusion-positioned lead groove, and the main shift is performed by the protrusion. The fork side end of the fork is temporarily pressed against the locking groove in which the fork side end is locked, and the rotation of the main shaft that supports the shifter gear in which the locking groove is formed is reduced. You may let them.

According to this configuration, if the gear stage where the hitting noise is to be reduced is an odd number, the odd number main shift fork is provided by providing a protrusion in the odd number main lead groove to form a protrusion arrangement lead groove. The lead groove side end is pressed toward the protruding direction of the protrusion, and the rotation of the odd-numbered stage drive shifter gear and the odd-numbered stage main shaft is decelerated, and the rotation of the odd-numbered free gear supported by the counter shaft is decelerated. it can. Similarly, if the gear position at which the hitting sound is to be reduced is an even number, the even-numbered main drive groove and the even-numbered main shaft of the even-numbered stage main shaft can be formed by providing a protrusion on the even-numbered main lead groove. The rotation can be decelerated, and the rotation of the even-numbered free gear supported by the counter shaft can be decelerated.
That is, the main shaft is composed of two odd-numbered stages and even-numbered stages, and the shift fork and the lead groove are divided into odd-numbered stages and even-numbered stages corresponding to the shifter gears supported by the respective main shafts. Even in the machine, the differential rotation between the shifter gear and the free gear is reduced by reducing the rotation on the fast side of the shifter gear and the free gear corresponding to the next gear position where the hitting sound is to be reduced. The hitting sound when the shifter side dog teeth engage with the free side dog teeth of the free gear can be reduced.

  The protrusion may be provided so as to protrude from the side wall surface of the main-side lead groove in the axial direction of the shift drum.

  According to this configuration, the fork side end portion of the shift fork is pressed in the axial direction of the shift drum from the protrusion during the shift up operation of the transmission, so that the fork side end portion of the shift fork is the locking groove of the shifter gear. Therefore, the rotation of the drive shifter gear and the main shaft is decelerated by the frictional force. Therefore, it is possible to decelerate the rotation of the shifter gear and free gear corresponding to the next shift stage, and to reduce the differential rotation between the gears of the next shift stage, and the shifter side dog teeth and the free side dog teeth are engaged. The sound of hitting can be reduced.

  Further, in the axial direction of the main shaft, the axial position of the drive shifter gear is set on the side of the drive shifter gear on the side where the fork side end of the main shift fork is pressed. A stopper plate to be regulated may be disposed adjacent to the drive shifter gear.

  According to this configuration, during the shift-up operation of the transmission, the fork side end of the shift fork is pressed in the axial direction of the shift drum by the protrusion, and the fork side end of the shift fork is on the side of the locking groove of the drive shifter gear. When pressed against the wall surface, the drive shifter gear is prevented from excessively moving in the axial direction, and the drive shifter gear is sandwiched between the stopper plate and the fork side end portion, and the rotation of the drive shifter gear and the main shaft is efficiently decelerated. It will be. Therefore, the differential rotation between the shifter gear and the free gear corresponding to the next shift stage can be efficiently decelerated, and the hitting sound when the shifter-side dog teeth and the free-side dog teeth are engaged can be reduced. .

  Further, the protrusion may be provided so as to protrude from the bottom wall surface of the main-side lead groove outward in the radial direction of the shift drum.

  According to this configuration, the fork side end of the shift fork is pressed in the rotation direction of the shift drum by the protrusion during the shift up operation of the transmission, so the main side shift fork is centered on the shift fork shaft. A part of the fork side end of the main shift fork is pressed against the bottom wall surface of the locking groove of the drive shifter gear to decelerate the rotation of the drive shifter gear and the main shaft. Therefore, it is possible to reduce the differential rotation between the shifter gear and the free gear corresponding to the next gear position, and it is possible to reduce the hitting sound when the shifter side dog teeth and the free side dog teeth are engaged.

  Further, a recess along the radial direction of the shift drum is formed at the lead groove side end portion of the main shift fork pressed by the protrusion, and an elastic member is formed in the recess, and the main member is formed by the elastic member. A ball member pressed against the bottom wall surface of the side lead groove may be accommodated.

  According to this configuration, during the shift-up operation of the transmission, the protrusion is pressed by the ball member in the rotation direction of the shift drum, and the main shift fork is moved so as to rotate about the shift fork shaft. A part of the fork side end of the side shift fork is pressed against the bottom wall surface of the locking groove of the drive shifter gear. When a pressure equal to or higher than a certain pressure is applied to the ball member, the elastic member contracts and the ball member is accommodated in the recess, so that the shift drum rotates while the protrusion pushes up the ball member. Therefore, the protrusion does not get caught by the fork side end protrusion of the main shift fork, and both the rotation of the shift fork and the smooth rotation of the shift drum can be achieved.

In the above-described shift drive mechanism for an internal combustion engine according to the present invention,
The shift fork has a main shift fork locked to the driving gear and a counter shift fork locked to the driven gear.
The shifter gear has a drive shifter gear supported by the main shaft and a driven shifter gear supported by the counter shaft,
Engage the fork side end of the main shift fork with the locking groove of the drive shifter gear,
The drive gear has a drive fixing gear that rotates integrally with the main shaft and is fixed so as not to move in the axial direction.
The protrusion is provided so as to protrude radially outward of the shift drum from the bottom wall surface of the main side lead groove with which the lead groove side end of the main side shift fork is engaged, During the upshifting operation of the machine, the projection presses the lead groove side end of the main shift fork so that the fork side end of the main shift fork is made to be more than normal by the projection. The rotation of the main shaft may be decelerated by temporarily pressing the locking groove of the drive shifter gear.

  According to this configuration, during the shift-up operation of the transmission, the fork side end of the shift fork is pressed in the rotation direction of the shift drum from the protrusion, so the main side shift fork is centered on the shift fork shaft. A part of the fork side end of the main shift fork is pressed against the bottom wall surface of the locking groove of the shifter gear, and the rotation of the drive shifter gear and the main shaft is decelerated. Therefore, even in a single clutch type transmission in which free gears are arranged on both sides of the drive shifter gear, it is possible to reduce the differential rotation between the shifter gear and the free gear corresponding to the next shift stage. The hitting sound when the dog teeth and the free-side dog teeth engage can be reduced.

  Further, a recess along the radial direction of the shift drum is formed at the lead groove side end portion of the main shift fork pressed by the protrusion, and an elastic member is formed in the recess, and the main member is formed by the elastic member. A ball member pressed against the bottom wall surface of the side lead groove may be accommodated.

  According to this configuration, during the shift-up operation of the transmission, the protrusion is pressed by the ball member in the rotation direction of the shift drum, and the main shift fork is moved so as to rotate about the shift fork shaft. A part of the fork side end of the side shift fork is pressed against the bottom wall surface of the locking groove of the drive shifter gear. When a pressure equal to or higher than a certain pressure is applied to the ball member, the elastic member contracts and the ball member is accommodated in the recess, so that the shift drum rotates while the protrusion pushes up the ball member. Therefore, the protrusion does not get caught by the fork side end protrusion of the main shift fork, and both the rotation of the shift fork and the smooth rotation of the shift drum can be achieved.

Of the shift fork guided by the main side lead groove , the fork side end that is the end of the shift fork that is locked to the shifter gear (Gs), the surface that is pressed against the shifter gear, or the shifter gear A rough surface portion with a high frictional resistance may be provided on at least one of the surfaces of the locking groove on which the fork side end is pressed.

  According to this configuration, a part of the fork side end portion of the shift fork guided by the main side lead groove is pressed against the wall surface of the locking groove of the shifter gear via the rough surface portion. It is possible to increase the frictional force between a part of the shaft and the wall surface of the locking groove of the shifter gear. Therefore, it is possible to efficiently reduce the rotation of the shifter gear and the main shaft, reduce the differential rotation between the shifter gear and the free gear corresponding to the next shift stage, and the shifter side dog teeth and the free side dog teeth are engaged. The hitting sound can be reduced.

  Further, the lead of the shift fork guided by the main side lead groove by the rotation of the shift drum from the neutral position of the transmission to the first speed position in the main side lead groove. The groove-side end portion may be provided in the middle of movement while being guided by the main-side lead groove.

  According to this configuration, during the shift-up operation from the neutral to the first speed of the transmission in which the differential rotation is likely to be large, the rotation of the shifter gear and the main shaft is decelerated, and the differential rotation between the shifter gear and the free gear corresponding to the first gear position is performed. Can be reduced, and the hitting sound when the shifter-side dog teeth and the free-side dog teeth are engaged can be reduced.

  A protrusion is formed on the inner surface of the lead groove of the shift drum with which the shift fork locked to the shifter gear supported by the main shaft is engaged, and the end of the shift fork on the lead groove side is pressed by this protrusion. The shift fork is pushed toward the protruding direction of the protrusion, and the shift fork is pushed against the locking groove of the shifter gear supported by the main shaft more than usual. Therefore, the rotation of the shifter gear supported by the main shaft and the main shaft can be decelerated, and the shifter gear and free gear can be decelerated by decelerating the faster rotation of the shifter gear or free gear corresponding to the next shift stage. , And the hitting sound when the shifter-side dog teeth of the shifter gear engage with the free-side dog teeth of the free gear can be reduced.

1 is a left side cross-sectional view of a vehicle-mounted internal combustion engine that includes a transmission drive mechanism for a transmission according to a first embodiment of the present invention. It is the II-II sectional view taken on the line of FIG. 1 of the transmission drive mechanism of the transmission which concerns on this invention. FIG. 3 is a partially enlarged view in which the left side of the transmission of FIG. 2 is enlarged from the right side wall of the crankcase. FIG. 3 is a partial enlarged view in which only a fork side end portion of a shift fork locked to the drive shifter gear and the drive shifter gear of FIG. 2 is enlarged. It is an expanded view of the lead groove | channel provided in the radial direction outer peripheral surface of a shift drum. It is a partial expanded sectional view of a drive gear, a driven gear, a shift fork, and a shift drum when the shift drum is in the second speed position. FIG. 6 is a partially enlarged view of the lead groove of FIG. 5 in which the second lead groove and the fourth lead groove are enlarged during a shift-up operation from the first speed position to the second speed position. It is a partial expanded sectional view of a drive gear, a driven gear, a shift fork, and a shift drum when the shift drum is in the first speed position. It is a partial expanded sectional view of a drive gear, a driven gear, a shift fork, and a shift drum when a shift drum is in a 2nd-speed dog tooth engagement position. It is a partial expanded sectional view of a drive gear, a driven gear, a shift fork, and a shift drum when a shift drum is in the 1st speed 2nd speed position. It is the comparison figure which compared the differential rotation of the 2nd speed driven gear and the 6th speed driven gear of the prior art example at the time of the shift up operation from the 1st speed position to the 2nd speed position, and this embodiment. FIG. 4 is an axial cross-sectional development view of a transmission drive mechanism for a transmission according to a second embodiment of the present invention, taken along line XII-XII in FIG. 1. It is the elements on larger scale which extracted the drive shifter gear of the transmission, and the fork side edge part of the main side shift fork. FIG. 13 is a development view of lead grooves provided on a radially outer peripheral surface of the shift drum of FIG. 12. It is the XV-XV sectional view taken on the line of FIG. It is the elements on larger scale which expanded the 2nd lead groove and the 4th lead groove at the time of upshifting operation from the 1st speed position to the 2nd speed position among the lead grooves of FIG. FIG. 13 is a cross-sectional view taken along line XVII-XVII in FIG. 12 in which the shift drum, the second shift fork, and the fourth speed drive gear are partially omitted when the shift drum is in the first speed position. FIG. 17 shows a state in which the shift drum rotates in the forward direction from the state shown in FIG. 17 and the protrusion comes into contact with the steel ball. The shift drum is further rotated in the forward direction from the state of FIG. 18, and the shift drum is in the second gear dog tooth engagement position. It is a modification of 2nd embodiment of the transmission drive mechanism of the transmission which concerns on this invention. It is the expanded sectional view which expanded a part of transmission and change mechanism of the transmission drive mechanism of the transmission which concerns on 3rd embodiment of this invention. It is the elements on larger scale which expanded the development view of the lead groove of a shift drum partially. FIG. 22 is a cross-sectional view taken along line XXIII-XXIII in FIG. 21 in which the shift drum, the second shift fork, and the third-speed drive gear are partially omitted when the shift drum is in the neutral position. FIG. 23 shows a state where the shift drum is temporarily rotated in the reverse direction from the state of FIG. 23 and the pin portion of the second shift fork is in contact with the protrusion. It is an axial sectional view of a transmission and a change mechanism in a 4th embodiment of a speed change drive mechanism of a transmission concerning the present invention. It is the elements on larger scale which expanded the fork side edge part of the main shaft of FIG. 25, the 3rd speed drive gear, the 4th speed drive gear, and the 1st shift fork. FIG. 26 is a sectional view taken along line XXVII-XXVII in a case where the pin portion of the shift drum and the first shift fork in FIG. 25 is in the neutral position. It is an expanded view of the lead groove | channel provided in the radial direction outer peripheral surface of a shift drum.

  FIG. 1 is a left side cross-sectional view of a vehicle-mounted internal combustion engine (hereinafter simply referred to as “internal combustion engine”) 1 provided with a speed change drive mechanism 20 of a transmission 21 according to a first embodiment of the present invention. The internal combustion engine 1 is a water-cooled V-type multi-cylinder four-stroke cycle internal combustion engine.

In the description and claims of the present specification, the directions such as front, rear, left, right, up, down, etc. indicate that the internal combustion engine 1 according to the present embodiment is mounted on a vehicle (not shown), for example, a motorcycle in a posture shown in FIG. Write according to the direction of the motorcycle.
In the posture shown in FIG. 1, the left side in the figure is the front of the vehicle, the upper side in the figure is the upper side of the vehicle, the rear side in the figure is the right side of the vehicle, and the front side in the figure is the left side of the vehicle.
In the figure, arrow FR indicates the front according to the direction of the vehicle, RE indicates the rear, LH indicates the left, RH indicates the right, UP indicates the upper side, and DW indicates the lower side.

  The “shift-up operation” in the description and claims of the present specification refers to a specific gear ratio such as a shift operation from the first speed to the second speed of the transmission 21 including a preparation state described later. A concept including not only a shift operation from a gear position having a gear position to the next gear position having a specific gear ratio but also a shift operation from the neutral position to the first gear position as the next gear position.

As shown in FIG. 1, the internal combustion engine 1 is a V-type multi-cylinder internal combustion engine in which the rotation center axis X of the crankshaft 7 is along the vehicle width direction (left-right direction). Cylinders 3A and 3B are erected. The front and rear cylinder heads 4A and 4B are overlaid on the front and rear cylinders 3A and 3B, respectively, and are further covered with front and rear cylinder head covers 5A and 5B.
Pistons 8 are fitted in the front and rear cylinders 3 </ b> A and 3 </ b> B so as to reciprocate, and each piston 8 is connected to a crank pin (not shown) of the crankshaft 7 via a connecting rod 9. A combustion chamber 10 is formed by the upper surface 8a of the piston 8 and the lower regions 4Aa and 4Ba of the front and rear cylinder heads 4A and 4B, and the crankshaft 7 is rotationally driven in conjunction with the sliding of the piston 8 due to combustion in the combustion chamber 10. It has become so.

  An oil pan 6 is attached below the crankcase 2, and oil is pumped to each part of the internal combustion engine 1 from the inside of the oil pan chamber 6 a formed by the oil pan 6 through the strainer 11 at the lower portion of the crankcase 2. An oil pump unit 12 is provided.

  A transmission 21 for shifting the rotational driving force of the internal combustion engine 1 to a predetermined gear stage is accommodated in the rear part of the crankcase 2, and a change mechanism 50 for switching the gear stage of the transmission 21 is accommodated above the transmission 21. Has been. A main shaft 22 that is an input shaft of the transmission 21, a counter shaft 25 that is driven by the main shaft 22, and an output shaft 33 that is driven by the counter shaft are behind the crankshaft 7, and the rotation center axis of the crankshaft 7. The rotation center axis parallel to X is arranged.

2 is a cross-sectional view taken along the line II-II of FIG. 1 of the speed change drive mechanism 20 of the transmission 21 according to the present invention.
As shown in FIG. 2, the transmission drive mechanism 20 includes a main shaft 22 that is an input shaft, a counter shaft 25 that is driven by the main shaft 22, and a hydraulic clutch that intermittently transmits the rotational driving force from the crankshaft 7. A change mechanism including a transmission 21 having 60, a shift drum 80 that is rotated when the transmission 21 is shifted, and a shift fork 72 that moves in the axial direction of the shift fork shaft 71 by the rotation of the shift drum 80 70, and the shift fork 72 is moved in the axial direction of the shift fork shaft 71 by the rotation of the shift drum 80, so that the gear stage of the transmission 21 is operated.
The main shaft 22, the counter shaft 25, the shift fork shaft 71, and the shift drum 80 are disposed inside the crankcase 2 so that the axis of rotation is parallel to the rotation center axis X of the crankshaft 7.

The crankcase 2 has a pair of left and right side walls 2L and 2R that face each other with an interval in the axial direction of the crankshaft 7.
The main shaft 22 of the transmission 21 includes a first main shaft 23 and a cylindrical second main shaft 24. The first main shaft 23 has a fixed axial relative position with respect to the second main shaft 24 and penetrates through the second main shaft 24. Between the first main shaft 23 and the second main shaft 24, a plurality of A needle bearing 26 is interposed. The left end 23a of the first main shaft 23 is rotatably supported by the left side wall 2L of the crankcase 2 via a ball bearing 27, and the right end 23b of the first main shaft 23 is rotatably supported by the right crankcase cover 14. Has been. The intermediate portion 24c of the second main shaft 24 passes through the right side wall 2R of the crankcase 2 and is rotatably supported by the right side wall 2R of the crankcase 2 via a ball bearing 28.

  The counter shaft 25 has a left end portion 25a rotatably supported on the left side wall 2L of the crankcase 2 via a ball bearing 29, and a right end portion 25b rotatable on the right side wall 2R of the crankcase 2 via a needle bearing 30. It is supported. Near the right end portion 25b of the counter shaft 25, a secondary drive gear 31 that meshes with the secondary driven gear 32 is spline-fitted.

FIG. 3 is a partially enlarged view in which the left side of the transmission 21 of FIG. 2 is enlarged from the right side wall 2R of the crankcase 2.
As shown in FIG. 3, between the left side wall 2L and the right side wall 2R of the crankcase 2 on the main shaft 22, six drive gears M corresponding to the first to sixth speeds are supported. Between the left side wall 2L of the crankcase 2 and the secondary drive gear 31 on the countershaft 25, six driven gears C corresponding to the drive gear M are always supported. The drive gear M and the driven gear C rotate together with the shafts (main shaft 22 and counter shaft 25) on which they are supported, and are fixed gears Gx that are fixed so as not to move in the axial direction, and shafts 22 on which each is supported. , 25 and a free gear Gf that is fixed so as not to move in the axial direction, and a shifter gear Gs that rotates together with the supported shaft and that can move in the axial direction.
Each gear has a reduction ratio that decreases from first to sixth.

The drive gear M rotates integrally with the main shaft 22 and is arranged to be movable in the axial direction of the main shaft 22. The drive gear M is rotatable relative to the main shaft 22. Drive free gears 45 and 46 that are fixed so as not to move, and drive fixed gears 41 and 42 that rotate integrally with the main shaft 22 and are fixed so that they cannot move in the axial direction of the main shaft 22 are provided.
Hereinafter, the first speed drive fixed gear is the first speed drive gear 41, the second speed drive fixed gear is the second speed drive gear 42, the third speed drive shifter gear is the third speed drive gear 43, and the fourth speed drive gear. The drive shifter gear is referred to as the fourth speed drive gear 44, the fifth speed drive free gear is referred to as the fifth speed drive gear 45, and the sixth speed drive free gear is referred to as the sixth speed drive gear 46.

The first-speed drive gear 41 serves as an odd-stage drive fixed gear, the third-speed drive gear 43 serves as an odd-stage drive shifter gear, and the fifth-speed drive gear 45 serves as an odd-stage drive free gear. . The odd speed drive gear Mo is configured by the first speed drive gear 41, the third speed drive gear 43 and the fifth speed drive gear 45. From the left side, the first speed drive gear 41, the fifth speed drive gear 45 and the third speed drive gear 43 are arranged in this order. Supported by the first main shaft 23, the first main shaft 23 serves as an odd-numbered main shaft.
In addition, the second speed drive gear 42 serves as an even stage drive fixed gear, the fourth speed drive gear 44 serves as an even stage drive shifter gear, and the sixth speed drive gear 46 serves as an even stage drive free gear. Plays. The second-speed drive gear 42, the fourth-speed drive gear 44, and the sixth-speed drive gear 46 constitute an even-numbered drive gear Me. The four-speed drive gear 44, the sixth-speed drive gear 46, and the second-speed drive gear 42 are arranged in this order from the left side. The second main shaft 24 is supported by the second main shaft 24 that is an even-numbered main shaft, and the second main shaft 24 serves as an even-numbered main shaft.

The driven gear C rotates in unison with the counter shaft 25 and can be moved relative to the counter shaft 25 in the axial direction of the counter shaft 25. It has the driven free gears 51-54 fixed so that it cannot move.
Hereinafter, the first-speed driven free gear is the first-speed driven gear 51, the second-speed driven free gear is the second-speed driven gear 52, the third-speed driven free gear is the third-speed driven gear 53, and the fourth-speed These driven free gears are referred to as a four-speed driven gear 54, a fifth-speed driven shifter gear is referred to as a five-speed driven gear 55, and a sixth-speed driven shifter gear is referred to as a six-speed driven gear 56.

The fifth-speed driven gear 55 serves as an odd-stage driven shifter gear, the first-speed driven gear 51 and the third-speed driven gear 53 serve as odd-stage driven free gears, and the sixth-speed driven gear 56 serves as an even-stage driven shifter gear. The second-speed driven gear 52 and the fourth-speed driven gear 54 serve as even-stage driven free gears.
The first-speed driven gear 51, the third-speed driven gear 53, and the fifth-speed driven gear 55 constitute an odd-stage driven gear Co, and the second-speed driven gear 52, the fourth-speed driven gear 54, and the sixth-speed driven gear 56 are an even-stage driven gear Ce. Are respectively supported by the counter shaft 25 in the same order as the drive gears 41 to 46.

  The shifter gear Gs and the free gear Gf are arranged so as to be adjacent to each other, and the shifter gear Gs has a third speed drive gear 43, a fourth speed drive gear 44, a fifth speed driven gear 55, and a sixth speed driven gear 56, and is a free gear. Gf has a fifth speed drive gear 45, a sixth speed drive gear 46, a first speed driven gear 51, a third speed driven gear 53, a second speed driven gear 52, and a fourth speed driven gear 54.

Shifter-side dog teeth Gsd are formed on the surfaces orthogonal to the shafts 22 and 25 on which each of the shifter gears Gs is supported and facing the adjacent free gear Gf of the shifter gears Gs.
Specifically, the shifter-side dog tooth Gsd is a surface facing the left side surface 43L, which is a surface facing the fifth speed driving gear 45 of the third speed driving gear 43, and the sixth speed driving gear 46 of the fourth speed driving gear 44. The four-speed driven gear of the right side surface 44R, the left side surface 55L that faces the first speed driven gear 51 of the fifth speed driven gear 55, the right side surface 55R that faces the third speed driven gear 53, and the sixth speed driven gear 56. It is formed on the left side surface 56L that is a surface facing 54 and the right side surface 56R that is a surface facing the second-speed driven gear 52.

The surfaces of the free gears Gf that are orthogonal to the shafts 22 and 25 on which the free gears Gf are supported and that face the adjacent shifter gears Gs of the free gears Gf are detachably opposed to the shifter side dog teeth Gsd. Free side dog teeth Gfd are formed.
Specifically, the free-side dog teeth Gfd are surfaces facing the right side surface 45R, which is a surface facing the third speed driving gear 43 of the fifth speed driving gear 45, and the fourth speed driving gear 44 of the sixth speed driving gear 46. Left side 46L, right side 51R which is the surface facing the fifth speed driven gear 55 of the first speed driven gear 51, left side surface 53L which is the surface facing the fifth speed driven gear 55 of the third speed driven gear 53, fourth speed driven gear The right side surface 54R, which is a surface facing the sixth speed driven gear 56, and the left side surface 52L, which is the surface facing the sixth speed driven gear 56, of the second speed driven gear 52, are formed.

The shifter-side dog teeth Gsd and the free-side dog teeth Gfd engage with each other when the shifter gear Gs approaches the corresponding free gear Gf so that they cannot rotate relative to each other, and when the shifter gear Gs separates from the corresponding free gear Gf. The engagement is released.
In the following description, the state where the shifter gear Gs and the free gear Gf are engaged refers to the state where the shifter-side dog teeth Gsd and the free-side dog teeth Gfd are engaged.

  A fork side end 72b of a shift fork 72, which will be described later, is locked to the outer peripheral surfaces 43P, 44P, 55P (5-6) P of the shifter gears 43, 44, 55, 56 along the circumferential direction. Grooves 43a, 44a, 55a, 56a are formed, respectively.

FIG. 4 is a partially enlarged view in which only the drive shifter gears 43 and 44 of FIG. 2 and the fork side end portion 72b of the shift fork 72 locked to the drive shifter gears 43 and 44 are enlarged.
As shown in FIGS. 3 and 4, the surface of the wall surface 47 of the locking groove 43 a formed in the third-speed drive gear 43 is located on the side where the fifth-speed drive gear 45, which is a free gear to be engaged, is not present. Among the wall surface 47 of the locking groove 44a formed in the right wall surface 47R and the fourth speed drive gear 44, the left wall surface 47L located on the side where the sixth speed drive gear 46 which is the free gear to be engaged is not present, A rough surface portion 48 having increased frictional resistance by forming a plurality of slit-shaped dents on the surface is provided.
The rough surface portion 48 only needs to increase the frictional resistance of the wall surface 47, and the shape thereof is not limited to the slit shape, and may be a double or a wave shape such as a file.

As shown in FIGS. 3 and 4, the right side located on the side where the five-speed drive gear 45 which is a free gear to be engaged is not located, and the four-speed drive gear 44 on the side of the third-speed drive gear 43. On the left side located on the side where the six-speed drive gear 46, which is the free gear to be engaged, is not present, the axial direction of both drive shifter gears 43, 44 is adjacent to both drive shifter gears 43, 44. A stopper plate 49 for restricting the position is provided.
A disk-shaped washer is used for the stopper plate 49, and the stopper plate 49 is supported on the first main shaft 23 protruding to the left of the second main shaft 24 so as to be rotatable relative to the first main shaft 23. .

As shown in FIG. 2, a hydraulic clutch 60 is provided on the right half 22 </ b> R of the main shaft 22 that is arranged to protrude rightward from the right side wall 2 </ b> R of the crankcase 2.
The hydraulic clutch 60 includes a first hydraulic clutch 61A that is an odd-numbered hydraulic clutch coupled to the first main shaft 23, a second hydraulic clutch 61B that is an even-numbered hydraulic clutch coupled to the second main shaft 24, and a clutch outer 63. It is comprised as what is called a dual clutch (twin clutch) system. The first clutch inner 62A of the first hydraulic clutch 61A is restricted from moving in the axial direction in the vicinity of the right end 23b of the first main shaft 23 arranged to protrude rightward from the right end 24b of the second main shaft 24. Splined. The second clutch inner 62B of the second hydraulic clutch 61B is spline-fitted in the vicinity of the right end portion 24b of the second main shaft 24 with limited axial movement.

  The clutch outer 63 is supported by a primary driven gear 64 that is rotatably supported by the second main shaft 24 between the first hydraulic clutch 61A and the right side wall 2R of the crankcase 2 via a buffer member 65. The primary driven gear 64 meshes with the primary drive gear 13 fitted on the crankshaft 7 so that the rotational driving force supplied from the crankshaft 7 is decelerated at a predetermined reduction ratio and transmitted to the hydraulic clutch 60. It has become.

Between the clutch outer 63 and the first clutch inner 62A, a drive friction plate 66a1 that rotates together with the clutch outer 63 and a driven friction plate 66a2 that rotates together with the first clutch inner 62A are alternately arranged. One friction plate group 66A is provided so as to be pressurized by the first pressure plate 67A. Further, between the clutch outer 63 and the second clutch inner 62B, a driving friction plate 66b1 that rotates together with the clutch outer 63 and a driven friction plate 66b2 that rotates together with the second clutch inner 62B are alternately arranged. The second friction plate group 66B is provided so as to be pressurized by the second pressure plate 67B.
A hydraulic circuit 68 capable of selectively driving the first pressure plate 67A and the second pressure plate 67B is provided on the second main shaft 24 and the right crankcase cover 14, and the rotational driving force from the crankshaft 7 is provided. The first hydraulic clutch 61 </ b> A and the second hydraulic clutch 61 </ b> B can be switched by connecting and disconnecting with hydraulic pressure.

Next, the change mechanism 70 will be described.
As shown in FIG. 2, the change mechanism 70 includes a shift drum 80 and a plurality of shift forks 72, and the shift fork 72 is moved in the axial direction by the rotation of the shift drum 80 to shift the shifter gear of the transmission 21. Gs is moved in the axial direction to switch the gear position of the transmission 21.

The shift fork 72 included in the change mechanism 70 includes a first shift fork 73, a second shift fork 74, a third shift fork 75, and a fourth shift fork 76, and each base 73a, 74a, 75a, 76a is a shift fork. The shaft 71 is supported so as to be slidable in the axial direction. Pin portions 73c, 74c, 75c, 76c, which are end portions on the side of cylindrical lead grooves, are provided on the base portions 73a, 74a, 75a, 76a of the first to fourth shift forks 73, 74, 75, 76. It is formed so as to protrude toward the lead groove 81 of the drum 80.
The shift fork 72 is broadly divided into a main shift fork 72A extending to the main shaft 22 and a counter shift fork 72B extending to the counter shaft 25. The main shift fork 72A includes the first shift fork 73 and the second shift fork 72A. The counter side shift fork 72B includes a third shift fork 75 and a fourth shift fork 76.

The first shift fork 73 serves as an odd-numbered main shift fork that extends toward the third-speed drive gear 43 that is an odd-stage drive shifter gear, and the second shift fork 74 is a four-speed drive that is an even-stage drive shifter gear. It functions as an even-numbered main shift fork extending toward the gear 44.
The third shift fork 75 serves as an odd-stage counter-side shift fork that extends toward the fifth-speed driven gear 55 that is an odd-stage driven shifter gear, and the fourth shift fork 76 is a six-stage driven shifter gear. It plays the role of an even-stage counter side shift fork extending toward the fast driven gear 56.

Referring also to FIG. 3, the fork side end 72 b of the shift fork 72 located on the shifter gear Gs side is provided in the locking grooves 43 a, 44 a, 55 a, 56 a provided in the shifter gears 43, 44, 55, 56. The shifter gears 43, 44, 55, 56 are locked so as to be rotatable, and the shifter gears 43, 44, 55, 56 are moved in the axial direction as the shift fork 72 moves in the axial direction. ing.
Specifically, the fork side end 73 b of the first shift fork 73 is locked in the locking groove 43 a of the third speed drive gear 43, and the fork side end 74 b of the second shift fork 74 is fixed to the fourth speed drive gear 44. The fork side end portion 75b of the third shift fork 75 is locked in the locking groove 55a of the fifth speed driven gear 55, and the fork side end portion 76b of the fourth shift fork 76 is set to the sixth speed. It is locked in the locking groove 56 a of the driven gear 56.

As shown in FIGS. 2 and 4, the right side surface 73bR of the fork side end portion 73b of the first shift fork 73 and the left side surface 74bL of the fork side end portion 74b of the second shift fork 74 have a plurality of slit-like shapes. A rough surface portion 77 provided with a recess to increase the frictional resistance is provided.
The rough surface portion 77 only needs to increase the frictional resistance of the respective fork side end portions 73b and 74b, and the shape thereof is not limited to the slit shape, and may be a double shape such as a file or a wave shape. .

As shown in FIG. 2, the shift drum 80 included in the change mechanism 70 is formed in a hollow cylindrical shape, and the right end portion 80a is rotatably supported on the right side wall 2R of the crankcase 2 via a ball bearing 87. The left end portion 80b is rotatably supported by the left side wall 2L of the crankcase 2 via a needle bearing 88.
An intermittent feed mechanism 95 for intermittently rotating the shift drum 80 is provided at the right end portion 80a of the shift drum 80. The intermittent feed mechanism 95 is shifted via a reduction gear mechanism 98, a shift spindle 97, and a master arm 96. It is rotated intermittently by the rotational driving force supplied from the motor 99.

FIG. 5 is a development view of the lead groove 81 provided on the radially outer peripheral surface 80 c of the shift drum 80.
In FIG. 5, the solid circle in the lead groove 81 indicates the pin portions 73c, 74c, 75c, 76c of the shift forks 73, 74, 75, 76 (not shown) in which the shift drum 80 is in the neutral position P (nn). The broken-line circles indicate the pin portions 73c, 74c, 75c, 76c of the shift forks 73, 74, 75, 76 at the gear positions P (nn) to P (6-n) indicated by the two-dot chain line. Is shown.

  As shown in FIGS. 2 and 5, a plurality of (four in the present embodiment) lead grooves 81 are provided on the radially outer peripheral surface 80 c of the shift drum 80. As shown in FIG. 5, the lead groove 81 is a wall surface 82 of the right wall surface 82R, the left wall surface 82L, and the bottom wall surface 82B of the space formed by being recessed from the outer peripheral surface 80c of the shift drum 80 inward in the radial direction of the shift drum 80. Is formed as a pattern along the circumferential direction of the shift drum 80 while being partially offset in the axial direction of the shift drum 80.

The lead groove 81 includes a main lead groove 81A having a first lead groove 83 serving as an odd-numbered main-side lead groove, a second lead groove 84 serving as an even-numbered main-side lead groove, and odd-numbered counter-side leads. It is roughly divided into a third lead groove 85 serving as a groove and a counter side lead groove 81B having a fourth lead groove 86 serving as an even-numbered counter side lead groove.
The first lead groove 83 has a pin portion 73c of the first shift fork 73, the second lead groove 84 has a pin portion 74c of the second shift fork 74, and the third lead groove 85 has a third shift fork. The pin portion 75c of the 75 and the pin portion 76c of the fourth shift fork 76 are slidably engaged with the fourth lead groove 86, respectively.
By rotating the shift drum 80, the respective pin portions 73c, 74c, 75c, 76c are guided according to the patterns of the lead grooves 83, 84, 85, 86 of the shift drum 80, so that the shift forks 73, 74, 75 are provided. , 76 move on the shift fork shaft 71 in the axial direction.

The shift drum 80 includes a neutral position P (nn), a first speed position P (1-n), a first speed second speed position P (1-2), a second speed position P (n-2), and a second speed third speed position. P (3-2), 3rd speed position P (3-n), 3rd speed 4th speed position P (3-4), 4th speed position P (n-4), 4th speed 5th speed position P (5-4) The fifth gear position P (5-n), fifth gear sixth gear position P (5-6), and sixth gear position P (n-6) are set sequentially at intervals of 30 degrees. .
Here, the notation in parentheses of the symbol attached to each gear position is that the number on the left side of the hyphen “-” is the gear position of the first main shaft 23 (odd number main shaft), and the number on the right side is the second main shaft 24. The gear positions of (even-numbered main shafts) are shown. “N” means neutral. For example, if P (1-2), the gear position of the first main shaft 23 is the first speed, and the gear position of the second main shaft 24 is the second speed.
Since the main side shift fork 72A and the counter side shift fork 72B are arranged at different positions in the circumferential position of the shift drum 80, the gears in the main side lead groove 82A and the counter side lead groove 81B in FIG. The positions P (nn) to P (6-n) are different.

  Next, the movement of the shift fork 72, each drive gear M, and each driven gear C at each gear position during the shift-up operation of the transmission 21 will be described below with reference to FIGS.

  When the shift drum 80 is in the neutral position P (n−n), the shifter gear Gs is in a neutral position that is not engaged with the free gear Gf.

When the shift drum rotates 30 degrees from the neutral position P (nn) in the forward direction SU, which is the upshift direction, the pin portion 75c of the third shift fork 75 moves to the left, and the shifter side dog of the fifth speed driven gear 55 The fifth-speed driven gear 55 and the first-speed driven gear 51 pass through the first-speed dog tooth engagement position A1n, which is the dog-tooth engagement position A where the tooth Gsd and the free-side dog tooth Gfd of the first-speed driven gear 51 engage. The engaged state is established, and the shift drum 80 is in the first speed position P (1-n) where the first speed of the transmission 21 is established.
The dog tooth engagement position A is a lead groove 81 that defines the position of the shifter gear Gs when the shifter gear Gs moves and the shifter side dog teeth Gsd first contact and engage with the free side dog teeth Gfd. Indicates the position of each pin portion 73c, 74c, 75c, 76c.

When the shift drum 80 further rotates 30 degrees in the forward direction SU from the first speed position P (1-n), the pin portion 76c of the fourth shift fork 76 moves to the right side, and the shifter side dog teeth of the sixth speed driven gear 56 The sixth-speed driven gear 56 is engaged with the second-speed driven gear 52 via the second-speed dog tooth engagement position A12, which is the dog-tooth engagement position A where Gsd and the free-side dog tooth Gfd of the second-speed driven gear 52 engage. As a result, the shift drum 80 is in the first-speed / second-speed position P (1-2) of the transmission 21 in the second-speed preparation state.
Here, the ready state means that the shift gear Gs and the free gear Gf of the current shift stage and the next shift stage are engaged with each other, and the first hydraulic clutch 61A or the second hydraulic clutch 61B corresponding to the current shift stage has a hydraulic pressure. Is in a connected state, indicating a state in which a slight hydraulic pressure is supplied to the first hydraulic clutch 61A or the second hydraulic clutch 61B corresponding to the next gear position. In this case, the first main shaft 23 and the second main shaft 24 rotate at substantially the same number of revolutions, but the first friction plate group 66A or the second friction plate group 66B corresponding to the next shift stage slides. Thus, the output of the transmission 21 is the output of the current gear stage. That is, in the first speed second speed position P (1-2), which is the second speed ready state, the first hydraulic clutch 61A is in a connected state and the second hydraulic clutch 61B is in a connected state to which a slight hydraulic pressure is supplied. The transmission 21 has a first speed output.
FIG. 6 is a partially enlarged cross-sectional view of the drive gear M, the driven gear C, the shift fork 71 and the shift drum 80 when the shift drum 80 is in the second speed position P (n-2). When the shift drum 80 is further rotated 30 degrees in the forward direction SU from the first and second speed position P (1-2), the pin portion 75c of the third shift fork 75 moves to the neutral position on the right side, as shown in FIG. As described above, the fifth-speed driven gear 55 is disengaged from the first-speed driven gear 51 and is in the neutral position, and the shift drum 80 establishes the second speed P (n−2) for establishing the second speed of the transmission 21. ).

When the shift drum 80 further rotates 30 degrees in the forward direction SU from the second speed position P (n-2), the pin portion 75c of the third shift fork 75 moves to the right side, and the shifter side dog teeth of the fifth speed driven gear 55 The fifth-speed driven gear 55 is engaged with the third-speed driven gear 53 via the third-speed dog tooth engagement position A23, which is the dog-tooth engagement position A where Gsd and the free-side dog tooth Gfd of the third-speed driven gear 53 engage. As a result, the shift drum 80 is in the second speed third speed position P (3-2) in the third speed ready state of the transmission 21.
When the shift drum 80 is further rotated 30 degrees in the forward direction SU from the second and third speed positions P (3-2), the pin portion 76c of the fourth shift fork 76 moves to the neutral position on the left side, and the sixth speed driven gear. 56 is disengaged from the second speed driven gear 52 and is in the neutral position, and the shift drum 80 is in the third speed position P (3-n) that establishes the third speed of the transmission 21.

When the shift drum 80 rotates further 30 degrees in the forward direction SU from the third speed position P (3-n), the pin portion 76c of the fourth shift fork 76 moves to the left side, and the shifter side dog teeth of the sixth speed driven gear 56 The sixth-speed driven gear 56 is engaged with the four-speed driven gear 54 via a fourth-speed dog engagement position A34, which is a dog-tooth engagement position A where Gsd and the free-side dog teeth Gfd of the fourth-speed driven gear 54 are engaged. As a result, the shift drum 80 is in the three-speed four-speed position P (3-4) of the transmission 21 in the four-speed ready state.
When the shift drum 80 rotates further 30 degrees in the forward direction SU from the third speed fourth speed position P (3-4), the pin portion 75c of the third shift fork 75 moves to the left neutral position, and the fifth speed driven gear 55 Is disengaged from the third-speed driven gear 53 and is in a neutral position, and the shift drum 80 is in the fourth-speed position P (n-4) that establishes the fourth speed of the transmission 21.

When the shift drum 80 is further rotated 30 degrees in the forward direction SU from the fourth speed position P (n-4), the pin portion 73c of the first shift fork 73 is moved to the left side, and the shifter side dog teeth of the third speed drive gear 43 are moved. The third-speed drive gear 43 is engaged with the fifth-speed drive gear 45 through the fifth-speed dog gear engagement position A45, which is the dog-tooth engagement position A where Gsd and the free-side dog teeth Gfd of the fifth-speed drive gear 45 are engaged. As a result, the shift drum 80 is in the fourth speed fifth speed position P (5-4) in the fifth speed ready state of the transmission 21.
When the shift drum 80 rotates further 30 degrees in the forward direction SU from the fourth speed fifth speed position P (5-4), the pin portion 76c of the fourth shift fork 76 moves to the neutral position on the right side, and the sixth speed driven gear 56 Is disengaged from the four-speed driven gear 54 and is in the neutral position, and the shift drum 80 is in the fifth speed position P (5-n) where the fifth speed of the transmission 21 is established.

When the shift drum 80 further rotates 30 degrees in the forward direction SU from the fifth speed position P (5-n), the pin portion 74c of the second shift fork 74 moves to the right side, and the shifter side dog teeth of the fourth speed drive gear 44 The four-speed drive gear 44 is engaged with the six-speed drive gear 46 via a sixth-speed dog gear engagement position A56, which is a dog-tooth engagement position A where Gsd and the free-side dog teeth Gfd of the six-speed drive gear 46 are engaged. As a result, the shift drum 80 is in the fifth speed sixth speed position P (5-6) of the transmission 21 in the sixth speed ready state.
When the shift drum 80 rotates further 30 degrees in the forward direction SU from the fifth speed sixth speed position P (5-6), the pin portion 73c of the first shift fork 73 moves to the neutral position on the right side, and the third speed drive gear 43 Is disengaged from the fifth speed drive gear 45 and is in the neutral position, and the shift drum 80 is in the sixth speed position P (n-6) at which the sixth speed of the transmission 21 is established.
The process of the upshifting operation of the transmission 21 has been described above, but the downshifting operation is performed by driving in reverse to this.

As shown in FIG. 5, the first lead groove 83 and the second lead groove 84 among the lead grooves 81 are provided with protrusions 90 having a substantially obtuse triangular shape when viewed in the radial direction of the shift drum 80.
The protrusion 90 provided in the first lead groove 83 allows a part of the left wall surface 82L of the wall surface 82 forming the first lead groove 83 to be guided from the left wall surface 82L to the first lead in the axial direction of the shift drum 80. The first lead groove 83, which is the inner side of the groove 83, protrudes toward the center C83 in the width direction, and the top portion 90a at the protruding position is a neutral position P (nn) of the first lead groove 83. To the first-speed dog tooth engagement position A1n and the second-speed position P (n-2) to the third-speed dog tooth engagement position A23.
Further, the protrusion 90 provided in the second lead groove 84 has a part of the right wall surface 82R out of the wall surface 82 forming the second lead groove 84 in the axial direction of the shift drum 80 from the right wall surface 82R. The lead 90 is formed so as to protrude toward the center C84 in the width direction of the second lead groove 84, which is the inner side of the lead groove 84, and the top portion 90a at the protruding position is a first speed position P ( 1-n) to the second gear dog tooth engagement position A12 and between the third gear position P (3-n) to the fourth gear dog gear engagement position A34. ing.

  By arranging the protrusion 90 in this way, as will be described later, before the shifter side dog teeth Gsd of the shifter gear Gs of the next shift stage engage with the free side dog teeth Gfd of the corresponding free gear Gf. The main-side shift fork 72A is temporarily pressed against the locking grooves 43a, 44a of the drive shifter gears 43, 44 by the projection 90, so that either the first main shaft 23 or the second main shaft 24 rotates. Has been slowed down.

  In the present embodiment, the inner side of the lead groove 81 refers to the width direction center C81 of the width from the left wall surface 82L to the right wall surface 82R of the lead groove 81. Further, the projecting portion arranged lead groove 89 which is the lead groove 81 provided with the projecting portion 90 is only the first lead groove 83 and the second lead groove 84 in the present embodiment.

Of the right wall surface 82R of the first lead groove 83, a portion of the right wall surface 82R is formed to be recessed in an arc shape toward the right in the axial direction of the shift drum 80 at a position facing the protrusion 90. An indented portion 91 is provided. Further, a part of the left wall surface 82L is recessed in an arc shape toward the left in the axial direction of the shift drum 80 at a position facing the protrusion 90 in the left wall surface 82L of the second lead groove 84. A formed recess 91 is provided.
The recessed portion 91 is for maintaining the distance between the right wall surface 82R and the left wall surface 82L of the projecting portion lead groove 89 so that the pin portions 73c and 74c of the first and second shift forks 73 and 74 can slide. In the axial direction of the shift drum 80, the protrusion 90 is recessed to the same length as the protrusion.

Next, the operation of the first embodiment of the speed change drive mechanism 20 of the transmission 21 according to the present invention will be described with reference to the upshifting operation from the first speed position P (1-n) to the second speed position P (n-2). Will be described with reference to the drawings.
7 shows the second lead groove 84 and the fourth lead groove 86 during the shift-up operation from the first speed position P (1-n) to the second speed position P (n-2) among the lead grooves 81 shown in FIG. It is the elements on larger scale which expanded.
FIG. 8 is a partially enlarged cross-sectional view of the drive gear M, the driven gear C, the shift fork 72, and the shift drum 80 when the shift drum 80 is in the first speed position P (1-n). FIG. 7 is a partially enlarged cross-sectional view of the drive gear M, the driven gear C, the shift fork 72 and the shift drum 80 when the shift drum 80 rotates in the forward direction from the state and is in the second gear dog tooth engagement position A12. 9, the drive gear M, the driven gear C, the shift fork 72, and the shift drum 80 when the shift drum 80 rotates in the forward direction SU from the state of FIG. 9 and is in the first speed second speed position P (1-2). FIG.

As shown in FIGS. 7 and 8, when the shift drum 80 is in the first speed position P (1-n), the fifth speed driven gear 55 moves to the left side, and the shifter side dog of the fifth speed driven gear 55 is moved. The tooth Gsd is engaged with the free-side dog tooth Gfd of the first-speed driven gear 51. The other shifter gears 43, 44, and 56 are in neutral positions that do not engage with the other free gears 45, 46, 52, and 54.
Referring also to FIG. 2, at this time, the hydraulic pressure is supplied to the first hydraulic clutch 61A which is an odd-numbered hydraulic clutch, and the first main clutch 23 which is the odd-numbered main shaft rotates by connecting the first hydraulic clutch 61A. The rotation of the first main shaft 23 is transmitted to the counter shaft 25 via the first speed drive gear 41, the first speed driven gear 51, and the fifth speed driven gear 55, and the counter shaft 25 is determined from the rotational speed of the first main shaft 23. Rotating at a reduced speed according to the speed ratio for the first speed. In this state, the six-speed driven gear 56 also rotates at the same rotational speed as the counter shaft 25.
On the other hand, a small amount of hydraulic pressure is also supplied to the second hydraulic clutch 61B, which is the even-numbered hydraulic clutch of the second main shaft 24, which is the even-numbered main shaft 24 at the neutral position P (nn). The main shaft 23 rotates at substantially the same rotational speed, and the rotation of the second main shaft 24 is transmitted to the second-speed driven gear 52 via the second-speed drive gear 42. The second-speed driven gear 52 rotates the second main shaft 24. The number of rotations is reduced according to the speed ratio for the second speed. Since the speed ratio for the second speed is smaller than the speed ratio for the first speed, the second speed driven gear 52 rotates at a faster speed than the sixth speed driven gear 56, and the second speed driven gear 52 and the sixth speed driven gear A differential rotation occurs with the gear 56.

Next, a state in which the shift drum 80 rotates in the forward direction SU and the shift drum 80 is in the second speed dog tooth engagement position A12 will be described.
As shown in FIGS. 7 and 9, the fifth-speed driven gear 55 is kept engaged with the first-speed driven gear 51. Since the pin portion 76c of the fourth shift fork 76 is located at the second speed dog tooth engagement position A12, the sixth speed driven gear 56 is guided to the fourth lead groove 86 of the shift drum 80 and moves slightly to the right. The shifter-side dog teeth Gsd of the sixth-speed driven gear 56 are close to the position where they come into contact with and engage with the free-side dog teeth Gfd of the second-speed driven gear 52.

In the second shift fork 74, the pin portion 74c passes through the position where the projecting portion 90 of the second lead groove 84 is provided, and the projecting portion 90 presses the pin portion 74c to the left side. It is pushed to the left.
At that time, the left side surface 74bL of the fork side end portion 74b of the second shift fork 74 is pressed against the left wall surface 47L of the locking groove 44a of the fourth speed drive gear 44 that is an even-stage drive shifter gear, and the fourth speed drive gear 44 is Is pressed against the stopper plate 49 adjacent thereto, and its rotation is decelerated. When the rotation of the four-speed drive gear 44 is decelerated, the rotation of the second main shaft 24 that rotates together with the four-speed drive gear 44 is decelerated, and the second speed that rotates together with the second main shaft 24. The rotation of the drive gear 42 is also decelerated. The second-speed drive gear 42 meshes with the second-speed driven gear 52, and the rotation of the second-speed driven gear 52 is decelerated.

  These series of speed reduction actions are such that when the pin portion 74 c passes the top 90 a of the projection 90, that is, the shifter-side dog tooth Gsd of the sixth-speed driven gear 56 engages with the free-side dog tooth Gfd of the second-speed driven gear 52. Since the rotation of the second-speed driven gear 52 is still decelerated at the second-speed dog tooth engagement position A12 which is maximum immediately before and exceeds the top 90a, the sixth-speed driven gear 56 and the second-speed driven gear The difference in rotation with 52 is reduced, the shifter-side dog tooth Gsd of the sixth-speed driven gear 56 can be suppressed from generating hitting sound when engaged with the free-side dog tooth Gfd of the second-speed driven gear 52, and The hitting sound can be reduced.

As described above, the left side surface 74bL of the fork side end 74b of the second shift fork 74 is provided with the rough surface portion 77 having a high frictional resistance, and is formed on the left wall surface 47L of the locking groove 44a of the four-speed drive gear 44. Is provided with a rough surface portion 48 having a high frictional resistance, and the fork side end portion 74b of the second shift fork 74 is pressed against the locking groove 44a of the four-speed drive gear 44 through the rough surface portions 48, 77, resulting in efficiency. The above-mentioned deceleration action can be often achieved.
In the present embodiment, the rough surface portions 48 and 77 are provided so as to oppose both the fork side end portions 73b and 74b and the locking grooves 43a and 44a, but are provided on either one of them. If it is, the same effect can be acquired.

As shown in FIG. 10, when the shift drum 80 is further rotated in the forward direction SU and is in the first speed second speed position P (1-2), the fifth speed driven gear 55 is changed to the first speed driven gear 51. The state engaged with is held. The sixth-speed driven gear 56 is guided to the fourth lead groove 86 of the shift drum 80 and moves to the right side. The shifter-side dog teeth Gsd of the sixth-speed driven gear 56 are moved to the driven free-side dog teeth of the second-speed driven gear 52. The state is engaged with Gfd. Further, the pin portion 74c of the second shift fork 74 passes through the region where the projection 90 is disposed, and is released from the state where the second shift fork 74 is pressed to the left side, and returns to the neutral position. In this state, the shifter-side dog teeth Gsd of the sixth-speed driven gear 56 are engaged with the free-side dog teeth Gfd of the second-speed driven gear 52, and the second-speed driven gear 52 rotates the same as the sixth-speed driven gear 56. Rotating by number.
As described above, in this state, a slight hydraulic pressure is supplied to the second hydraulic clutch 61B, and even if the second main shaft 24 rotates at a higher rotational speed than the first main shaft 23, As the second friction plate group 66B of the second hydraulic clutch 61B slides, the output of the transmission 21 is maintained in the first speed state, and the transmission 21 is in the second speed ready state.

FIG. 11 shows the conventional example and the two-speed driven gear 52 and the six-speed driven gear 56 of the present embodiment when shifting up from the first speed position P (1-n) to the second speed position P (n-2). It is the comparison figure which compared these differential rotations.
As shown in FIG. 11, as preconditions, the rotational speed of the crankshaft 7 is 2520 rpm, the reduction ratio of the primary reduction gear 15 composed of the primary drive gear 13 and the primary driven gear 64 is 1.8, and the first speed drive is performed. The reduction ratio between the gear 41 and the first-speed driven gear 51 is “2.4”, and the reduction ratio between the second-speed drive gear 42 and the second-speed driven gear 52 is “1.8”.

  The differential rotation between the second speed driven gear 52 and the sixth speed driven gear 56 of the conventional example and the present embodiment when the shift drum 80 is at the first speed position P (1-n) is specifically calculated below. Referring also to FIG. 8, when the shift drum 80 is in the first speed position P (1-n), the rotational power of the crankshaft 7 is decelerated via the primary speed reducer 15 and transmitted to the first main shaft 23. The rotation speed of the first main shaft 23 is 1400 rpm (2520 rpm / 1.8). At this time, as described above, since the second main shaft 24 also rotates at the same rotational speed as the first main shaft 23, the rotational speed of the second main shaft 24 is 1400 rpm. The rotational power of the first main shaft 23 is transmitted to the counter shaft 25 via the first speed drive gear 41, the second speed driven gear 52, and the fifth speed driven gear 55. At this time, the rotation speed of the counter shaft 25 is 583 rpm (1400 rpm / 2.4) which is the rotation speed at which the rotation of the first main shaft 23 is decelerated between the first-speed drive gear 41 and the first-speed driven gear 51. . Further, the six-speed driven gear 56 that is the shifter gear Gs on the counter shaft 25 rotates integrally with the counter shaft 25, and the rotation speed of the six-speed driven gear 56 is 583 rpm. On the other hand, the second-speed driven gear 52 that is the free gear Gf on the counter shaft 25 is rotated by the second-speed drive gear 42. At this time, the rotation speed of the second-speed driven gear 52 is 778 rpm (1400 rpm / 1.8) as the rotation of the second main shaft 24 is decelerated between the second-speed drive gear 42 and the second-speed driven gear 52. That is, when the shift drum 80 is at the first speed position P (1-n), the differential rotation between the second speed driven gear 52 and the sixth speed driven gear 56 is 194 rpm (778 rpm-583 rpm). In the conventional example, the sixth-speed driven gear 56 is engaged with the second-speed driven gear 52 with this differential rotation of 194 rpm.

  However, in the present embodiment, the rotation of the four-speed drive gear 44 (ie, the rotation of the second main shaft 24) is performed by the second shift fork 74 immediately before the sixth-speed driven gear 56 is engaged with the second-speed driven gear 52. It is slowing down. For example, when the amount of deceleration is 150 rpm, the rotation speed of the fourth speed drive gear 44 (that is, the rotation speed of the second main shaft 24) is 1250 rpm, and the rotation speed of the second speed driven gear 52 is 694 rpm (1250 rpm / 1.8). ). That is, in the present embodiment, the differential rotation between the second speed driven gear 52 and the sixth speed driven gear 56 immediately before the sixth speed driven gear 56 is engaged with the second speed driven gear 52 is 111 rpm (694 rpm−583 rpm). . This is because the differential rotation between the second-speed driven gear 52 and the sixth-speed driven gear 56 is reduced by 83 rpm (194 rpm−111 rpm) as compared with the conventional example, and the reduction rate is 43%. As described above, only by reducing the rotational speed of the second main shaft 24 by about 10%, the differential rotation between the second-speed driven gear 52 and the sixth-speed driven gear 56 is reduced by 43%, and the internal combustion engine according to the present embodiment. The first shift drive mechanism 20 can greatly reduce the differential rotation between the shifter gear Gs and the free gear Gf corresponding to the next shift stage even if the amount of deceleration of the main shaft 22 corresponding to the next shift stage is small. It has become.

  This decelerating action is similarly performed in the up-shifting operation to another gear stage in which the protrusion 90 is provided. For example, when performing a shift-up operation from the neutral position P (nn) to the first speed position P (1-n), the fork side end portion 73b of the first shift fork 73 immediately before the first speed dog tooth engagement position A1n. The right side surface 73bR is pressed against the right wall surface 47R of the locking groove 43a of the third speed drive gear 43 to decelerate the rotation of the third speed drive gear 43 and the first main shaft 23 and rotate integrally with the first main shaft 23. By decelerating the rotation of the first-speed driven gear 51 via the first-speed drive gear 41, the differential rotation between the five-speed driven gear 55 and the first-speed driven gear 51 that are not rotating is reduced.

  As described above, in the present embodiment, the fork side end portions 73b and 74b of the first and second shift forks 73 and 74 are pressed against the side wall surfaces 47L and 47R of the locking grooves 43a and 44a of the drive shifter gears 43 and 44. As a result, the rotation of the drive shifter gears 43 and 44 is decelerated, and the rotation of either the first main shaft 23 or the second main shaft 24 corresponding to the next gear stage is decelerated. Since the drive shifter gears 43 and 44 are structured to move so as to engage with the adjacent drive free gears 45 and 46, the projecting portion 90 must be provided in order to achieve a deceleration action as in the present embodiment. The pin portions 73c and 74c of the first and second shift forks 73 and 74 need to be provided so as to press in the direction in which the drive free gears 45 and 46 to which the drive shifter gears 43 and 44 are engaged do not exist. Is done. That is, the protrusion 90 is provided on the side wall surfaces 82L and 82R in the direction in which the drive free gears 45 and 46 to which the corresponding drive shifter gears 43 and 44 are engaged are present among the wall surfaces 82 of the main lead groove 81A. From the side wall surfaces 82L and 82R, the drive free gears 45 and 46 to be engaged are projected in a direction in which they do not exist.

The first embodiment of the present invention described above has the following effects.
Of the lead groove 81, the left wall surface 82L of the first lead groove 83 with which the pin portion 73c of the first shift fork 73 is engaged is part of the left wall surface 82L from the left wall surface 82L to the inside of the first lead groove 83. A projecting portion 90 is formed so as to project toward the center C83 in the width direction of the first lead groove 83 which is the side. The protrusion 90 has a top 90a at the protruding position between the neutral position P (nn) of the first lead groove 83 and the first-speed dog tooth engagement position A1n and the second-speed position P (n-2 ) To the third gear dog tooth engagement position A23. Therefore, before the shifter side dog teeth Gsd of the driven shifter gear 55 corresponding to the next shift stage are engaged with the free side dog teeth Gfd of the driven free gears 51 and 53 during the upshifting operation to the first speed or the third speed, The projecting portion 90 pushes the pin portion 73c of the first shift fork 73 to the right in the axial direction of the shift drum 80, and the fork side end portion 73b of the first shift fork 73 is to the right of the locking groove 43a of the three-speed drive gear 43. By pressing against the wall surface 47R, the rotation of the first main shaft 23, which is an odd-numbered main shaft, is decelerated, and the rotation of the driven free gears 51 and 53 corresponding to the next gear is decelerated, so that the next gear is achieved. The differential rotation between the corresponding driven shifter gear 55 and the driven free gears 51 and 53 is reduced, and the shifter side dog teeth Gsd of the driven shifter gear 55 and the free side dog teeth Gfd of the driven free gears 51 and 53 corresponding to the next shift speed are reduced. Reduces the hitting sound when engaging It is possible.

  On the other hand, a part of the right wall surface 82R from the right wall surface 82R to the right wall surface 82R of the second lead groove 84 to which the lead groove side end portion 74c of the second shift fork 74 is engaged is the second groove. A protrusion 90 is formed so as to protrude toward the center C84 in the width direction of the second lead groove 84, which is the inside of the lead groove 84. The protrusion 90 has a top 90a at the protruding position between the first speed position P (1-n) of the second lead groove 84 and the second speed dog tooth engagement position A12 and the third speed position P ( 3-n) to the fourth-speed dog tooth engagement position A34. Therefore, before the shifter side dog teeth Gsd of the driven shifter gear 56 corresponding to the next shift stage are engaged with the free side dog teeth Gfd of the driven free gears 52 and 54 during the upshifting operation to the second speed or the fourth speed, The projecting portion 90 pushes the pin portion 74c of the second shift fork 74 to the left in the axial direction of the shift drum 80, and the fork side end portion 74b of the second shift fork 74 moves to the left of the locking groove 44a of the four-speed drive gear 44. By pressing against the wall surface 47L, the rotation of the second main shaft 24, which is the even-numbered main shaft, is decelerated, and the rotation of the driven free gears 52 and 54 corresponding to the next gear is decelerated, so that the next gear is achieved. The differential rotation between the corresponding driven shifter gear 56 and the driven free gears 52 and 54 is reduced, and the shifter side dog teeth Gsd of the driven shifter gear 56 and the free side dog teeth Gfd of the driven free gears 52 and 54 corresponding to the next shift speed are reduced. It is possible to reduce the hitting sound when engaging That.

  That is, even in the DCT transmission 21 having the two main shafts 22, before the shifter-side dog teeth Gsd corresponding to the next shift stage engage with the free-side dog teeth Gfd, the next shift stage By reducing the rotation of the main shaft 22 on the side corresponding to the speed of the free gear Gf corresponding to the next gear stage, the rotation of the free gear Gf corresponding to the next gear stage can be reduced via the main shaft 22 and the occurrence of hitting sound can be reduced. It is possible to reduce the differential rotation between the shift gear Gs and the free gear Gf at the desired gear, and it is possible to reduce the striking sound when the shifter-side dog teeth Gsd and the free-side dog teeth Gfd are engaged.

  In the axial direction of the main shaft 22, the locking groove 43 a of the third speed drive gear 43 is on the right side where the locking groove 43 a is pressed against the fork side end 73 b of the first shift fork 73, and the locking groove 44 a of the fourth speed drive gear 44. A stopper plate 49 for restricting the axial positions of the drive gears 43, 44 is provided on the drive gears 43, 44 on the left side, which is the side pressed against the fork side end 74b of the second shift fork 74. It is arrange | positioned so that it may be pinched | interposed adjacently. Therefore, when the fork side end portion 73b of the first shift fork 73 is pressed against the right wall surface 47R of the locking groove 43a of the third speed drive gear 43, the third speed drive gear 43 has the fork side end portion 73b and the stopper plate 49. Thus, it is possible to prevent the third speed drive gear 43 from excessively moving in the axial direction and to efficiently decelerate the rotation of the first main shaft 23. Further, when the fork side end portion 74b of the second shift fork 74 is pressed against the left wall surface 47L of the locking groove 44a of the fourth speed drive gear 44, the fourth speed drive gear 44 is connected to the fork side end portion 74b and the stopper plate 49. Thus, it is possible to prevent the fourth-speed drive gear 44 from excessively moving in the axial direction and to efficiently decelerate the rotation of the second main shaft 24. That is, the rotation of the first and second main shafts 23 and 24 corresponding to the next gear stage is efficiently decelerated, and the differential rotation between the shift gear Gs and the free gear Gf of the gear stage where the hitting sound is to be reduced is efficiently reduced. Therefore, it is possible to reduce the hitting sound when the shifter side dog teeth Gsd and the free side dog teeth Gfd are engaged.

  A rough surface portion 77 is provided on the right side surface 73bR of the fork side end portion 73b of the first shift fork 73 and the left side surface 74bL of the fork side end portion 74b of the second shift fork 74. A rough surface portion 48 is provided on the right wall surface 47R of the locking groove 43a of the third speed drive gear 43 and the left wall surface 47L of the locking groove 44a of the fourth speed drive gear 44. During the upshifting operation of the transmission 21, the fork side end portions 73b, 74b of the main side shift forks 73, 74 are formed in the locking grooves 43a, 44a of the drive shifter gears 43, 44 through the rough surface portions 48, 77. It becomes possible to increase the frictional force when pressed against the wall surfaces 47R and 47L, and to efficiently decelerate the rotation of the first main shaft 23 or the second main shaft 24 corresponding to the next shift stage. As described above, the rotation of the first and second main shafts 23 and 24 corresponding to the next shift stage can be efficiently decelerated, and the differential rotation of the shift stage at which the hitting sound is to be reduced can be efficiently reduced. This makes it possible to reduce the hitting sound when the shifter-side dog teeth Gsd and the free-side dog teeth Gfd are engaged.

  Further, in the first embodiment, the projecting portion 90 is formed so that the pin portion 72Ac of the main side shift fork 72A is connected to the main side lead groove 81A according to the rotation of the shift drum 80 when the transmission 21 is shifted up. The following gear position P (1-n), P from one gear position P (nn), P (1-n), P (n-2), P (3-n) While shifting to (1-2), P (3-2), P (3-4), the shifter side dog teeth Gsd of the shifter gear Gs of the next gear stage and the free side dog teeth Gfd of the free gear Gf The pin portion 72Ac may be pressed until the dog tooth engagement position A is engaged, and the position of the top portion 90a is not limited to the position of the present embodiment.

  Furthermore, in the first embodiment, the shape of the protrusion 90 is not limited to a substantially obtuse triangular shape in the radial direction of the shift drum 80, and an arc shape, a rectangular shape, or the like does not depart from the spirit of the present invention. Can be changed.

  In the first embodiment, the first main shaft 23 is an odd-numbered stage and the second main shaft 24 is an even-numbered stage. A similar effect can be obtained even with the transmission 21 having the main shaft 24 as an odd number.

Next, a second embodiment of the transmission drive mechanism 20 of the transmission 21 according to the present invention will be described with reference to the drawings.
12 is an axial cross-sectional development view of the transmission drive mechanism 20 of the transmission 21 according to the second embodiment of the present invention, taken along the line XII-XII of FIG. 1, and FIG. 21 is a partially enlarged view of the drive shifter gears 43 and 44 of 21 and the fork side end 72Ab of the main side shift fork 72A extracted and enlarged. FIG. FIG. 14 is a development view of the lead groove 81 provided on the radially outer peripheral surface 80c of the shift drum 80 of FIG. 12, and FIG. 15 shows the first speed and the second speed of the pin portion 74c of the shift drum 80 and the second shift fork 74. It is the XV-XV sectional view taken on the line of FIG. 12 in the speed position P (1-2).
As shown in FIG. 12, in the second embodiment, most of the configuration is the same except for the first embodiment described above and the protrusion 110 described later, and its operation, and the same member. Are denoted by the same reference numerals and description thereof is omitted.

As shown in FIGS. 12 and 13, the bottom wall surface 47B of the locking groove 43a formed in the third-speed drive gear 43 and the bottom wall surface 47B of the locking groove 44a formed in the fourth-speed drive gear 44 A rough surface portion 48 having increased frictional resistance by forming a plurality of slit-like recesses is provided.
The rough surface portion 48 only needs to increase the frictional resistance of the wall surface 47, and the shape thereof is not limited to the slit shape, and may be a double or a wave shape such as a file.

The inner surface 73bB of the fork side end 73b of the first shift fork 73 and the inner side surface 74bB of the fork side end 74b of the second shift fork 74 are provided with a plurality of slit-shaped recesses to increase the frictional resistance. A surface portion 77 is provided.
The rough surface portion 77 only needs to increase the frictional resistance of the respective fork side end portions 73b and 74b, and the shape thereof is not limited to the slit shape, and may be a double shape such as a file or a wave shape. .

As shown in FIG. 15, the lead groove side end surface 73d (odd number not shown) of the pin portion 73c of the first shift fork 73 and the lead groove side end surface 74d of the pin portion 74c of the second shift fork 74 are shifted to each other. A concave portion 100 that is recessed in a cylindrical shape along the radial direction of the drum 80 toward the shift fork shaft 71 is formed.
The recess 100 accommodates a coil spring 101 that is an elastic member and a steel ball 102 that is a ball member. The steel ball 102 accommodated in the concave portion 100 of the first shift fork 73 is urged by the coil spring 101 along the concave portion 100 and pressed against the bottom wall surface 82B of the first lead groove 83 (the odd-numbered stages are not shown). ). Further, the steel ball 102 accommodated in the recess 100 of the second shift fork 74 is urged by the coil spring 101 along the recess 100 and pressed against the bottom wall surface 82B of the second lead groove 84.

As shown in FIGS. 14 and 15, the first lead groove 83 and the second lead groove 84 are provided with a substantially hemispherical protrusion 110.
The protrusion 110 provided in the first lead groove 83 is a first lead located radially outward of the shift drum 80 from the width direction center C83 of the bottom wall surface 82B of the wall surface 82 forming the first lead groove 83. It is provided so as to protrude toward the middle in the depth direction of the groove 83 (the odd-numbered steps are not shown), and its top 110a is engaged with the first-speed dog teeth from the neutral position P (nn) of the first lead groove 83. Between position A1n, between 2nd speed position P (n-2) to 3rd speed dog tooth engagement position A23 and between 4th speed position P (n-4) to 5th speed dog tooth engagement position A45 It is arranged in three places so as to be located.
Further, the protrusion 110 provided in the second lead groove 84 is a first one located radially outward of the shift drum 80 from the center C84 in the width direction of the bottom wall surface 82B of the wall surface 82 forming the second lead groove 84. The second lead groove 84 is provided so as to protrude toward the middle Cm84 in the depth direction, and the top portion 110a thereof extends from the first speed position P (1-n) of the second lead groove 84 to the second speed dog tooth engagement position. Between A3, 3rd speed position P (3-n) to 4th gear dog tooth engagement position A34 and 5th speed position P (5-n) to 6th gear dog tooth engagement position A56 It is arranged in three places.

In other words, as in the first embodiment, the protrusion 110 is moved before the shifter-side dog tooth Gsd of the shifter gear Gs of the next shift stage is engaged with the free-side dog tooth Gfd of the corresponding free gear Gf. The main shaft 23 or the second main shaft 24 is disposed so as to decelerate the rotation.
Here, the inner side of the lead groove 81 in the present embodiment refers to a position that is the center C81 in the width direction of the lead groove 81 and the middle Cm81 in the depth direction of the lead groove 81. Further, in the present embodiment, the first lead groove 83 and the second lead groove 84 serve as the projecting portion arranged lead groove 89.

16 shows the second lead groove 84 and the fourth lead groove 86 during the shift-up operation from the first speed position P (1-n) to the second speed position P (n-2) among the lead grooves 81 shown in FIG. It is the elements on larger scale which expanded. In FIG. 16, the double circle indicates the pin portion 74c and the concave portion 100 of the second shift fork 74, and the single circle indicates the pin portion 76c of the fourth shift fork 76.
The operation of the second embodiment of the speed change drive mechanism 20 of the transmission 21 according to the present invention is exemplified by a shift up operation from the first speed position P (1-n) to the second speed position P (n-2). This will be described below with reference to FIGS. The movement of the fifth speed driven gear 55 and the sixth speed driven gear 56 during the upshifting operation from the first speed position P (1-n) to the second speed position P (n-2) is the same as that of the first embodiment. The details of the operations that are the same as those of the first embodiment are omitted.

17 is a cross-sectional view taken along the line XVII-XVII of FIG. 12 in which the shift drum 80, the second shift fork 74, and the fourth speed drive gear 44 are partially omitted when the shift drum 80 is at the first speed position P (1-n). It is.
As shown in FIG. 17, the lead groove side end surface 74 d of the pin portion 74 c of the second shift fork 74 has a top 110 a of the protrusion 110 provided in the second lead groove 84 as viewed in the axial direction of the shift drum 80. The steel ball 102, which is located radially outward of the shift drum 80 with respect to the orbit Q, and is housed in the recess 100 formed in the pin portion 74c, is formed in the second lead groove 84 by the biasing force of the coil spring 101. It is pressed against the bottom wall surface 82B.
Referring to FIG. 8, when shift drum 80 is in first speed position P (1-n), fifth speed driven gear 55 moves to the left side as in the first embodiment, and fifth speed driven The shifter-side dog teeth Gsd of the gear 55 are engaged with the free-side dog teeth Gfd of the first-speed driven gear 51, and the second-speed driven gear 52, which is the next shift stage, is faster than the six-speed driven gear 56. Rotation causes a differential rotation between the second speed driven gear 52 and the sixth speed driven gear 56.

FIG. 18 shows a state in which the shift drum 80 is rotated in the forward direction SU from the state of FIG. 17 and the protrusion 110 is in contact with the steel ball 102.
This state is a position displayed in Pa in FIG. As shown in FIG. 18, when the protrusion 110 comes into contact with the steel ball 102 and the steel ball 102 is pressed by the protrusion 110 in the forward rotation direction SU of the shift drum 80, the second shift fork 74 When the pin portion 74c is pushed by the steel ball 102, the second shift fork 74 rotates about the shift fork shaft 71 in the direction CW opposite to the rotation direction of the shift drum 80, and the fork side end portion 74b The inner side surface 74bB of the fork side end portion 74b1 near the pin portion 74c is pressed against the bottom wall surface 47B of the locking groove 44a of the four-speed drive gear 44. The four-speed drive gear 44 is pressed toward the second main shaft 24 by the fork side end 74b, and its rotation is decelerated. Referring also to FIG. 9, when the rotation of the four-speed drive gear 44 is decelerated, the rotation of the second main shaft 24 rotating integrally with the four-speed drive gear 44 is reduced as in the first embodiment. The rotation of the second-speed drive gear 42 that is decelerated and rotates integrally with the second main shaft 24 is also decelerated. The second-speed drive gear 42 meshes with the second-speed driven gear 52, and the rotation of the second-speed driven gear 52 is decelerated.

  Further, when the shift drum 80 rotates in the forward direction SU, the steel ball 102 is housed in the recess 100 due to contraction of the coil spring 101 that has lost the pressing force from the projection 110, and the projection 110 is stored in the steel ball 102. Is moved while being pushed into the recess 100. During this time, the state in which the four-speed drive gear 44 is pressed against the second main shaft 24 by the fork side end 74b is maintained.

FIG. 19 shows a case where the shift drum 80 further rotates in the forward direction SU from the state of FIG. 18 and the shift drum 80 is at the second-speed dog tooth engagement position A12.
As shown in FIG. 19, the steel ball 102 is housed inside the recess 100 by the protrusion 110, and the second-speed driven gear 52 continues to decelerate. Therefore, as in the first embodiment, the differential rotation between the second-speed driven gear 52 and the sixth-speed driven gear 56 decreases, and the shifter-side dog teeth Gsd of the sixth-speed driven gear 56 are driven by the second-speed driven gear 52. It is possible to suppress the generation of a hitting sound when engaged with the free-side dog teeth Gfd and reduce the hitting sound.

As described above, the inner surface 74bB of the fork side end 74b of the second shift fork 74 is provided with the rough surface portion 77 having a high frictional resistance, and is formed on the bottom wall surface 47B of the locking groove 44a of the four-speed drive gear 44. Is provided with a rough surface portion 48 having a high frictional resistance, so that the deceleration action can be efficiently achieved.
In the present embodiment, the rough surface portions 48 and 77 are provided so as to oppose both the fork side end portions 73b and 74b and the locking grooves 43a and 44a, but are provided on either one of them. If it is, the same effect can be acquired. Further, the rough surface portion 77 is provided only on the inner side surfaces 73bB and 74bB of the fork side end portions 73b1 and 74b1 on the side pressed against the locking grooves 43a and 44a among the inner side surfaces 73bB and 74bB of the fork side end portions 73b and 74b. May be.

The second embodiment of the present invention described above has the following effects.
Of the lead grooves 81, the bottom wall surface 82B of the first lead groove 83 with which the pin portion 73c of the first shift fork 73 is engaged is located radially outward of the shift drum 80 from the center C83 in the width direction of the bottom wall surface 82B. A protrusion 110 is provided so as to protrude toward the middle (not shown) in the depth direction of the first lead groove 83 located. The protrusion 110 has a top 110a between the neutral position P (nn) of the first lead groove 83 and the first speed dog tooth engagement position A1n and from the second speed position P (n-2) to the third speed dog. It is arranged at two places so as to be located between the tooth engagement position A23.
Further, a recess 100 in which the coil spring 101 and the steel ball 102 are accommodated is formed on the lead groove side end surface 73d of the pin portion 73c of the first shift fork 73, and the steel ball 102 extends along the recess 100 to the coil spring 101. And is pressed against the bottom wall surface 82B of the first lead groove 83.

  According to the above configuration, the shifter-side dog teeth Gsd of the shifter gear 55 corresponding to the next shift stage are free of the free gears 51 and 53 when the transmission 21 is shifted up to an odd number (first speed, third speed). Before engaging with the side dog teeth Gfd, the pin portion 73c of the first shift fork 73 is pressed by the protrusion 110 in the forward direction SU of the shift drum 80 via the steel ball 102, and the first shift. The fork 73 rotates about the shift fork shaft 71 in the direction CW opposite to the rotation direction of the shift drum 80, and the fork side end 73 b of the first shift fork 73 is formed in the locking groove 43 a of the three-speed drive gear 43. By pressing against the bottom wall surface 47B, the rotation of the first main shaft 23, which is an odd-numbered main shaft, is decelerated, and the rotation of the driven free gears 51, 53 corresponding to the next gear is decelerated, thereby reducing the differential rotation, Shifter side dog teeth Gs of the shifter gear 55 corresponding to the next gear position And the free-side dog teeth Gfd of each free gears 51 and 53 can be reduced striking sound at the time of engagement.

On the other hand, among the lead grooves 81, the bottom wall surface 82B of the second lead groove 84 with which the pin portion 74c of the second shift fork 74 is engaged is radially outside the shift drum 80 from the center C84 in the width direction of the bottom wall surface 82B. A projecting portion 110 is provided so as to project toward the middle Cm84 in the depth direction of the second lead groove 84 positioned in the direction. The protrusion 110 has a top portion 110a between the first speed position P (1-n) of the second lead groove 84 and the second speed dog tooth engagement position A12 and from the third speed position P (3-n). It is arranged at two places so as to be located between the four-speed dog tooth engagement position A34.
The lead groove side end surface 74d of the pin portion 74c of the second shift fork 74 is formed with a recess 100 in which the coil spring 101 and the steel ball 102 are accommodated, and the steel ball 102 extends along the recess 100. And is pressed against the bottom wall surface 82B of the second lead groove 84.

  According to the above configuration, the shifter-side dog tooth Gsd of the shifter gear 56 corresponding to the next shift stage is changed to the free-side dog teeth Gfd of the free gears 52 and 54 at the time of the shift-up operation to the even speed (second speed, fourth speed). Before engaging the pin, the projection 110 pushes the pin portion 74c of the second shift fork 74 through the steel ball 102 in the forward rotation direction of the shift drum 80, so that the second shift fork 74 is shifted. The fork shaft 71 rotates around the fork shaft 71 in a direction CW opposite to the rotation direction of the shift drum 80, and the fork side end 74b of the second shift fork 74 contacts the bottom wall surface 47B of the locking groove 44a of the four-speed drive gear 44. When pressed, the rotation of the second main shaft 24, which is the even-numbered main shaft, is decelerated, and the differential free rotation is reduced by decelerating the rotation of the driven free gears 52 and 54 corresponding to the next gear, so that the next gear The shifter side dog teeth Gsd of the shifter gear 56 corresponding to the And the free-side dog teeth Gfd gear 52, 54 can be reduced striking sound at the time of engagement.

  That is, even in the DCT transmission 21 having the two main shafts 22, before the shifter-side dog teeth Gsd corresponding to the next shift stage engage with the free-side dog teeth Gfd, the next shift stage By reducing the rotation of the main shaft 22 on the side corresponding to the speed of the free gear Gf corresponding to the next gear stage, the rotation of the free gear Gf corresponding to the next gear stage can be reduced via the main shaft 22 and the occurrence of hitting sound can be reduced. It is possible to reduce the differential rotation between the shift gear Gs and the free gear Gf at the desired gear, and it is possible to reduce the striking sound when the shifter-side dog teeth Gsd and the free-side dog teeth Gfd are engaged.

  Further, when a pressure higher than a certain pressure is applied to the steel ball 102, the coil spring 101 is contracted and the steel ball 102 is accommodated in the recess 100. When the steel ball 102 is pressurized above a certain pressure, the coil spring 101 contracts and the steel ball 102 is stored in the recess, so that the shift drum 80 rotates while the protrusion 110 pushes up the steel ball 102. Become. Therefore, the pin portions 73c and 74c of the main side shift forks 73 and 74 are not caught by the projection 110, and the smooth rotation of the shift drum 80 can be maintained.

  A rough surface portion 77 is provided on the inner side surface 73bB of the fork side end portion 73b of the first shift fork 73 and the inner side surface 74bB of the fork side end portion 74b of the second shift fork 74. A rough surface portion 48 is provided on the bottom wall surface 47B of the locking groove 43a of the third speed drive gear 43 and the bottom wall surface 47B of the locking groove 44a of the fourth speed drive gear 44. During the shift-up operation of the transmission 21, the fork side ends 73b and 74b of the first and second shift forks 73 and 74 are pressed against the wall surfaces 47B and 47B of the locking grooves 43a and 44a of the drive shifter gears 43 and 44. The frictional force at the time can be increased through the rough surface portions 48 and 77, and the rotation of the first main shaft 23 or the second main shaft 24 corresponding to the next shift stage can be efficiently reduced. Become. Then, the rotation of the free gear Gf or the shifter gear Gs corresponding to the next shift stage can be decelerated, and the differential rotation at the shift stage at which the generation of the hitting sound is suppressed can be reduced. The hitting sound when Gsd and free-side dog teeth Gfd are engaged can be reduced.

  In the second embodiment, the protrusions 110 are provided at four positions from the neutral position P (nn) to the fourth speed position P (n-4). It may be provided only in one of the two lead grooves 84, or may be provided corresponding to only one gear position where reduction of the hitting sound is necessary.

  In the second embodiment, the shape of the protrusion 110 is not limited to a hemispherical shape, and can be changed within a range that does not depart from the spirit of the present invention, such as a conical shape, a pyramidal shape, or a cubic shape.

  Further, in the second embodiment, the protrusion 110 is configured such that the pin portion 72Ac of the main shift fork 72A is connected to the main lead groove 81A in response to the rotation of the shift drum 80 when the transmission 21 is shifted up. The following gear position P (1-n), P from one gear position P (nn), P (1-n), P (n-2), P (3-n) While shifting to (1-2), P (3-2), P (3-4), the shifter side dog teeth Gsd of the shifter gear Gs of the next gear stage and the free side dog teeth Gfd of the free gear Gf The pin portion 72Ac may be pressed until the dog tooth engagement position A is engaged, and the position of the top portion 110a is not limited to the position of the present embodiment.

  In the second embodiment, the first main shaft 23 is an odd-numbered stage and the second main shaft 24 is an even-numbered stage. A similar effect can be obtained even with the transmission 21 having the main shaft 24 as an odd number.

  Further, as shown in FIG. 20, as a modification of the second embodiment, the lead groove side end face 73d of the pin portion 73c of the first shift fork 73 and the lead groove side of the pin portion 74c of the second shift fork 74 are shown. A configuration in which the concave portion 100 is not formed in the end surface 74d and the ball member 102 is not provided may be employed. In this case, for example, at the time of the upshift operation from the first speed position to the even speed stage of the second speed position as shown in FIG. 20, the protrusion 110 moves the corner portion 74 e of the pin portion 74 c of the second shift fork 74. The first shift fork 73 is rotated about the shift fork shaft 71, and the rotation of the first main shaft 23 is decelerated.

  In this modification, the pin portion 73c of the first shift fork 73 and the pin portion 74c of the second shift fork 74 are viewed in the axial direction of the shift drum 80, and the pivot center X80 of the shift drum 80 and the center X71 of the shift fork shaft. It may be engaged with the lead groove 81 of the shift drum 80 with an offset in the forward rotation direction of the shift drum 80 from the line connecting the two. In this case, the corners 73e and 74e of the pin portions 73c and 74c of the shift forks 73 and 74 do not approach the rotation center X80 side of the shift drum from the position at the time of contact with the protrusion 110, and each shift fork The pin portions 83c and 84c of 83 and 84 are not caught by the projection 110, and the smooth rotation of the shift drum 80 can be maintained.

Next, a third embodiment of the transmission drive mechanism 20 of the transmission 21 according to the present invention will be described with reference to the drawings.
FIG. 21 is an enlarged cross-sectional view of a part of the transmission 21 and the change mechanism 70 of the transmission drive mechanism 20 of the transmission 21 according to the third embodiment of the present invention. FIG. 22 is a partially enlarged development view in which a development view of the lead groove 81 of the shift drum 80 is partially enlarged. 23, the shift drum 80, the second shift fork 74, and the third-speed drive gear 43 are partially omitted from the cross-section taken along line XXIII-XXIII in FIG. 21 when the shift drum 80 is in the neutral position P (nn). It is sectional drawing.
In the third embodiment, the same members as those in the first and second embodiments described above are denoted by the same reference numerals and description thereof is omitted.

As shown in FIG. 21, in the third embodiment, the odd-numbered stage and the even-numbered stage in the main shaft 22 are switched from the first and second embodiments, and the first main shaft 23 is the even-numbered stage main shaft. In addition, the second main shaft 24 is an odd-numbered main shaft.
The second main shaft 24 is provided with an odd-numbered drive gear Mo from the right side in the order of a first-speed drive gear 41, a fifth-speed drive gear 45, and a third-speed drive gear 43. An odd-stage driven gear Co that meshes with the drive gear Mo is arranged in the order of a first-speed driven gear 51, a fifth-speed driven gear 55, and a third-speed driven gear 53 from the right side.
The third-speed drive gear 43 that is the shifter gear Gs is formed with a locking groove 43a as in the second embodiment, and the locking groove 43a is provided with a rough surface portion 48 on the bottom wall surface 47B, and an odd number of steps. A fork side end portion 74b of the second shift fork 74 serving as a main side shift fork is locked. The fifth-speed driven gear 55 is also formed with a locking groove 55a as in the second embodiment, and the locking groove 55a has a fourth shift fork 76 (which serves as an odd-stage counter side shift fork) Fork side end portion 76b (not shown) is locked.

As shown in FIGS. 21 and 22, the pin portion 74c of the second shift fork 74 functions as an odd-numbered main-side lead groove among the lead grooves 81 provided on the radially outer peripheral surface 80c of the shift drum 80. A second lead groove 84 is slidably engaged. The inner surface 74bB of the fork side end portion 74b of the second shift fork 74 is provided with a rough surface portion 77 having a plurality of dents to increase the frictional resistance as in the second embodiment.
Further, the pin portion 76c of the fourth shift fork 76 (not shown) is slidably engaged with the fourth lead groove 86 serving as an odd-stage counter side lead groove.

  As shown in FIGS. 22 and 23, the second lead groove 84 is formed with an interrupting portion 92 for interrupting between the neutral position P (n−n) and the sixth speed position P (n−6). The interrupting portion wall surface 93 facing the second lead groove 74 of the interrupting portion 92 constitutes a part of the wall surface 82 of the second lead groove 74 and is formed in a semicircular shape when the shift drum 80 is viewed in the circumferential direction.

As shown in FIGS. 22 and 23, a protrusion 120 is formed on the boundary between the neutral position side wall surface 93a on the neutral position P (nn) side and the bottom side wall 82B of the second lead groove 74 in the intermittent portion wall surface 93. Is provided.
The protrusion 120 is provided so as to protrude from the bottom wall surface 82B along the neutral position side wall surface 93a toward the middle Cm84 in the depth direction of the second lead groove 84 positioned radially outward of the shift drum 80. The shape of the second lead groove 84 is a stepped shape having a height up to the center Cm84 in the depth direction of the second lead groove 84 in the cross-sectional view at the middle C84 in the width direction. Has been.

That is, as in the second embodiment, the protrusion 120 is such that the shifter-side dog tooth Gsd of the fifth-speed driven gear 55 corresponding to the next shift stage engages with the free-side dog tooth Gfd of the first-speed driven gear 51. Before the rotation, the rotation of the second main shaft 24 is arranged to be decelerated.
Also in the present embodiment, the protrusion 120 is provided between the neutral position P (nn) and the dog tooth engagement position A1n, and the second lead groove 84 becomes the protrusion arrangement lead groove 89. .

Next, the operation of the third embodiment of the shift drive mechanism 20 of the transmission 21 according to the present invention will be described with reference to the drawings.
FIG. 24 shows a state in which the shift drum 80 is temporarily rotated in the reverse direction SD from the state of FIG. 23 and the pin portion 74 c of the second shift fork 74 is in contact with the protrusion 120.
As shown in FIG. 24, in the present embodiment, the transmission 21 is initially slightly reversed in the backward direction SD during the upshifting operation from the neutral P (nn) to the first speed position P (1-n). After rotating in the forward direction, it is rotated in the forward direction SU.

As shown in FIG. 24, when the shift drum 80 rotates in the reverse direction SD from the neutral position P (nn), the projecting portion 120 comes into contact with the pin portion 74c of the second shift fork 74, and the pin portion 74c becomes the projecting portion. 120, the shift drum 80 is pressed in the rotation direction (reverse direction SD), and, contrary to the second embodiment, the second shift fork 74 has a rotation direction of the shift drum 80 around the shift fork shaft 71. Rotates in the forward direction CCW which is the reverse direction, and the fork side end 74b2 far from the pin portion 74b of the fork side end 74b is pressed against the bottom wall surface 47B of the locking groove 43a of the three-speed drive gear 43. It is done. The third speed drive gear 43 is pressed toward the second main shaft 24 by the fork side end 74b, and the rotation thereof is decelerated. Referring also to FIG. 21, when the rotation of the third-speed drive gear 43 is decelerated, the rotation of the second main shaft 24 rotating integrally with the third-speed drive gear 43 is decelerated and integrated with the second main shaft 24. The rotation of the first-speed drive gear 41 that is rotating at a reduced speed is also reduced. The first-speed driven gear 51 meshes with the first-speed drive gear 41, and the rotation of the first-speed driven gear 51 is decelerated.
At this time, the counter shaft 25 is not rotating, and the rotation of the first-speed driven gear 51 is decelerated, so that the differential rotation between the five-speed driven gear 55 and the first-speed driven gear 51 that rotate integrally with the counter shaft 25 is reduced. Is reduced, and the occurrence of a hitting sound when the shifter-side dog tooth Gsd of the fifth-speed driven gear 55 and the free-side dog tooth Gfd of the first-speed driven gear 51 are engaged is suppressed, and the hitting sound can be reduced. It can be done.

As described above, the inner surface 74bB of the fork side end 74b of the second shift fork 74 is provided with the rough surface portion 77 having a high frictional resistance, and is formed on the bottom wall surface 47B of the locking groove 43a of the third speed drive gear 43. Is provided with a rough surface portion 48 having a high frictional resistance, so that the deceleration operation can be efficiently performed as in the second embodiment.
In the present embodiment, the rough surface portions 48 and 77 are provided so as to oppose both the fork side end portions 73b and 74b and the locking grooves 43a and 44a, but are provided on either one of them. If this is the case, the same effect can be obtained, and if it is provided in any case as in the present embodiment, a more suitable effect can be obtained. Further, the rough surface portion 77 may be provided only on the inner side surface 74bB of the fork side end portion 74b2 on the side pressed against the locking groove 43a in the inner side surface 74bB of the fork side end portion 74b.

The third embodiment of the present invention described above has the following effects.
Among the lead grooves 81, the boundary between the bottom wall surface 82B of the second lead groove 84 with which the pin portion 74c of the second shift fork 74 is engaged and the neutral position side wall surface 93a of the intermittent portion 92 is provided from the bottom wall surface 82B to the neutral. A projecting portion 120 is provided so as to project toward the middle Cm84 in the depth direction of the second lead groove 84 located radially outward of the shift drum 80 along the position side wall surface 93a.
The shift drive mechanism 20 of the transmission 21 has a mechanism in which the shift drum 80 rotates in the reverse direction SD at one end during a shift-up operation from the neutral position P (nn) to the first speed position P (1-n). When the shifter side dog tooth Gsd of the fifth speed driven gear 55 corresponding to the next shift stage is engaged with the free side dog tooth Gfd of the first speed driven gear 51, the second shift fork 74 is The pin portion 74c of the shift drum 80 is pressed in the rotation direction of the reverse direction SD of the shift drum 80, and the second shift fork 74 is moved in the forward direction CCW that is the reverse direction of the rotation direction of the shift drum 80 around the shift fork shaft 71. The fork side end 74b of the second shift fork 74 is pressed against the bottom wall surface 47B of the locking groove 43a of the third speed drive gear 43. Therefore, the rotation of the second main shaft 24, which is an odd-numbered main shaft, is decelerated, and by reducing the rotation of the first-speed driven gear 51 corresponding to the next shift stage, the differential rotation with the fifth-speed driven gear 55 is reduced, The hitting sound when the shifter-side dog tooth Gsd of the fifth-speed driven gear 55 corresponding to the next shift stage and the free-side dog tooth Gfd of the first-speed driven gear 51 are engaged can be reduced.

  A rough surface portion 77 having high frictional resistance is provided on the inner side surface 74bB of the fork side end portion 74b of the second shift fork 74, and a rough surface portion having high frictional resistance is provided on the bottom wall surface 47B of the locking groove 43a of the three-speed drive gear 43. 48 is provided. For this reason, the fork side end portion 74b of the second shift fork 74 is pressed against the bottom wall surface 47B of the locking groove 43a of the third speed drive gear 43 through the rough surface portions 48, 77, and the second main shaft 24 efficiently. Can be decelerated. Then, by decelerating the rotation of the first-speed driven gear 51, the differential rotation with the fifth-speed driven gear 55 is reduced, and the shifter-side dog teeth Gsd and the first-speed driven gear 51 of the fifth-speed driven gear 55 corresponding to the next shift stage are reduced. The hitting sound when the free side dog teeth Gfd are engaged can be reduced.

  In the third embodiment, the shape of the protrusion 120 is not limited to a crescent shape as viewed from the radial direction of the shift drum 80, and is changed within a range that does not depart from the spirit of the present invention, such as an arc shape or a rectangular shape. be able to.

Next, a fourth embodiment of the speed change drive mechanism 20 of the transmission 21 according to the present invention will be described with reference to the drawings.
FIG. 25 is an axial cross-sectional view of the transmission 21 and the change mechanism 70 in the fourth embodiment of the transmission drive mechanism 20 of the transmission 21 according to the present invention.
In the fourth embodiment, the second embodiment is adapted to the single clutch system, and the same reference numerals are used for the same members as those in the first embodiment and the second embodiment described above. The description is omitted.

As shown in FIG. 25, in the fourth embodiment, the main shaft 122 is single, and the left end 122a of the main shaft 122 rotates on the left side wall 2L of the crankcase 2 via a ball bearing 27. The central portion 122c is rotatably supported by the right side wall 2R of the crankcase 2 via a ball bearing 28, and the right end portion 122b is rotatably supported by the right crankcase cover 14.
A single hydraulic clutch 160 is provided on the right half 122R of the main shaft 122 that is arranged to protrude rightward from the right side wall 2R of the crankcase 2.

Between the left side wall 2L and the right side wall 2R of the crankcase 2 in the main shaft 122, six drive gears M corresponding to the first to sixth speeds are arranged from the left to the second speed drive gear 142 and the sixth speed drive gear 146. The third-speed drive gear 143, the fourth-speed drive gear 144, the fifth-speed drive gear 145, and the first-speed drive gear 141 are supported in this order. The first speed drive gear 141 and the second speed drive gear 142 are fixed gears Gx, the third speed drive gear 143 and the fourth speed drive gear 144 are integrally formed shifter gears Gs, the fifth speed drive gear 145 and the sixth speed drive gear. Reference numeral 146 denotes a free gear Gf.
The counter shaft 125 has six driven gears C corresponding to the drive gear M that are always meshed with the second gear driven gear 152, the sixth gear driven gear 156, the third gear driven gear 153, and the fourth gear from the left. The driven gear 154, the fifth speed driven gear 155, and the first speed driven gear 151 are supported in this order. The first-speed driven gear 151 to the fourth-speed driven gear 154 are free gears Gf, and the fifth-speed driven gear 155 and the sixth-speed driven gear 156 are shifter gears Gs.

FIG. 26 is a partially enlarged view of the main shaft 122, the third speed drive gear 143, the fourth speed drive gear 144, and the fork side end 173b of the first shift fork 173 in FIG.
As shown in FIG. 26, the third-speed drive gear 143 and the fourth-speed drive gear 144 are integrally formed, and the fork of the first shift fork 173, which will be described later, is formed on the outer peripheral surface 143P along the circumferential direction. A locking groove 143a for locking the side end 173b is formed. A rough surface portion 148 is provided on the bottom wall surface 147B of the locking groove 143a as in the second embodiment.

As shown in FIG. 25, the shift fork 172 included in the change mechanism 70 is different from the first to third embodiments, and the shift fork 172 extending toward the main shaft 122 serves as the main side shift fork 173. It is only a single first shift fork 173 that fulfills A fork side end 173b of the main shift fork 173 is locked in a locking groove 143a formed in the integrated third and fourth speed drive gears 143 and 144.
The counter-side shift fork 174 includes a second shift fork 175 locked in the locking groove 155a of the fifth speed driven gear 155 and a third shift fork 176 locked in the locking groove 156a of the sixth speed driven gear 156. Have.
As shown in FIG. 26, a rough surface portion 177 is provided on the inner side surface 173bB of the fork side end portion 173b of the first shift fork 173, as in the second embodiment.

FIG. 27 is a cross-sectional view taken along line XXVII-XXVII when the shift drum 80 of FIG. 25 and the pin portion 173c of the first shift fork 173 are at the neutral position Pn.
As shown in FIG. 27, the lead groove side end surface 173d of the pin portion 173c of the first shift fork 173 is formed on the shift fork shaft 71 along the radial direction of the shift drum 80, as in the second embodiment. A concave portion 178 that is recessed in a cylindrical shape is formed.
The recess 178 accommodates a coil spring 179 that is an elastic member and a steel ball 180 that is a ball member. The steel ball 180 accommodated in the recess 178 of the first shift fork 173 is urged by the coil spring 179 along the recess 178 and pressed against the bottom wall surface 186B of the first lead groove 183.

FIG. 28 is a development view of the lead groove 181 provided on the radially outer peripheral surface 80c of the shift drum 80. FIG.
In FIG. 28, the solid circle in the lead groove 181 indicates the pin portions 173c, 174c, and 175c of the first to third shift forks 173, 174, and 175 at the neutral position Pn, and the broken circle is a two-dot chain line. The pin portions 173c, 174c, and 175c at the gear positions Pn to P6 shown in FIG.

As shown in FIG. 27, the lead groove 181 includes a first lead groove 183 serving as a main-side lead groove, and a second lead groove 185 and a third lead groove 186 serving as a counter-side lead groove 184. Have.
The first lead groove 183 has a pin portion 173c of the first shift fork 173, the second lead groove 185 has a pin portion 175c of the second shift fork 175, and the third lead groove 186 has a third shift fork. 176 pin portions 176c are slidably engaged with each other.

  In the shift drum 80, the gear positions of the first speed position P1, the second speed position P2, the third speed position P3, the fourth speed position P4, the fifth speed position P5 and the sixth speed position P6 are sequentially set with an interval of 60 degrees. A neutral position Pn is set at an intermediate position between the first speed position P1 and the second speed position P2.

  Next, the movement of the shift fork 172, each drive gear M, and each driven gear C at each gear position during the shift-up operation of the transmission 21 will be described below with reference to FIGS.

  When the shift drum 80 is in the neutral position Pn, the shifter gear Gs is in a neutral position that is not engaged with the free gear Gf.

  When the shift drum 80 rotates from the neutral position Pn by 30 degrees in the direction SD (hereinafter referred to as “reverse direction”) where the first speed is established, the pin portion 176c of the third shift fork 176 moves to the right side, and the fifth speed driven. The fifth-speed driven gear 155 passes through the first-speed dog tooth engagement position A1, which is the dog-tooth engagement position A where the shifter-side dog tooth Gsd of the gear 155 and the free-side dog tooth Gfd of the first speed driven gear 151 engage. The shift drum 80 is engaged with the first speed driven gear 151, and the shift drum 80 is in the first speed position P1 where the first speed of the transmission 21 is established.

  When the shift drum 80 rotates 60 degrees from the first speed position P1 in the forward direction SU (the direction in which the second speed or higher is established; the same applies hereinafter), the pin portion 176c of the third shift fork 176 moves to the neutral position on the left side. The fifth-speed driven gear 155 is disengaged from the first-speed driven gear 151 to the neutral position, the pin portion 175c of the second shift fork 175 moves to the left side, and the shifter side dog teeth of the sixth-speed driven gear 156 Gsd and the free-side dog teeth Gfd of the second-speed driven gear 152 are engaged, and the shift drum 80 is in the second-speed position P2 of the transmission 21.

  When the shift drum 80 rotates 60 degrees in the forward direction SU from the second speed position P2, the pin portion 175c of the second shift fork 175 moves to the right side through the neutral position on the right side, and the sixth speed driven gear 156 becomes the second speed driven gear. It moves to the right side through the neutral position where the engagement with 152 is released, and the shifter side dog teeth Gsd of the sixth speed driven gear 156 and the free side dog teeth Gfd of the third speed driven gear 153 are engaged, The shift drum 80 is in the third speed position P3 of the transmission 21.

  When the shift drum 80 rotates 60 degrees in the forward direction SU from the third speed position P3, the pin portion 175c of the second shift fork 175 moves to the neutral position on the left side, and the sixth speed driven gear 156 and the third speed driven gear 153 The engagement is released to the neutral position, and the pin portion 176c of the third shift fork 176 moves further to the left, and the shifter side dog teeth Gsd of the fifth speed driven gear 155 and the free side dog teeth Gfd of the fourth speed driven gear 154. And the shift drum 80 is in the fourth speed position P4 of the transmission 21.

  When the shift drum 80 rotates 60 degrees in the forward direction SU from the fourth speed position P4, the pin portion 176c of the third shift fork 176 moves to the neutral position on the right side, and the sixth speed driven gear 156 and the fourth speed driven gear 154 The engagement is released to the neutral position, and the pin portion 173c of the first shift fork 173 further moves to the right, and the shifter side dog teeth Gsd and the fifth speed drive gear of the integrated third speed and fourth speed drive gears 143 and 144 are moved. 145 free side dog teeth Gfd are engaged, and the shift drum 80 is in the fifth speed position P5 of the transmission 21.

When the shift drum 80 rotates 60 degrees in the forward direction SU from the fifth speed position P5, the pin portion 173c of the first shift fork 173 moves to the left side through the neutral position on the left side, and the third and fourth speed drive gears 143 and 144 are moved. Moves to the left side through a neutral position where the engagement with the fifth speed drive gear 145 is released, and the shifter side dog teeth Gsd of the third speed and fourth speed drive gears 143 and 144 and the free side dog teeth of the sixth speed drive gear 146 Gfd is engaged, and the shift drum 80 is in the sixth speed position P6 of the transmission 21.
The process of the upshifting operation of the transmission 21 has been described above, but the downshifting operation is performed by driving in reverse to this.

As shown in FIGS. 27 and 28, the first lead groove 183 is provided with a substantially hemispherical protrusion 190 similar to the second embodiment.
The protrusion 190 provided in the first lead groove 183 is a first lead located radially outward of the shift drum 80 from the width direction center C183 of the bottom wall surface 182B in the wall surface 182 forming the first lead groove 183. The groove 183 is provided so as to protrude toward the middle Cm183 in the depth direction, and its top 190a is located between the neutral position Pn of the first lead groove 183 and the first gear dog tooth engagement position A1. It is arranged.
By arranging the protrusion 190 in this manner, the shifter-side dog tooth Gsd of the fifth-speed driven gear 155 is engaged with the free-side dog tooth Gfd of the first-speed driven gear 151, as in the second embodiment. Before starting, the rotation of the main shaft is decelerated.
In the present embodiment, the first lead groove 183 becomes the projecting portion arranged lead groove 89, and the definition of the inside of the lead groove 181 is the same as in the second embodiment.

The operation of the fourth embodiment of the speed change drive mechanism 20 of the transmission 21 according to the present invention will be described with reference to FIGS. 27 and 28, taking as an example a shift-up operation from the neutral position Pn to the first speed position P1. .
When the shift drum 80 is in the neutral position Pn, all the shifter gears Gs are in the neutral position. When the shift drum 80 rotates in the reverse direction SD, the protrusion 190 comes into contact with the steel ball 180 before the first gear dog tooth engagement position A1, and the first shift fork 173 is the same as in the third embodiment. Rotates about the shift fork shaft 71 in the direction CCW opposite to the rotation direction of the shift drum 80, and the inner side surface 173bB of the fork side end 173b2 on the side farther from the pin 173c of the fork side end 173b, It is pressed against the bottom wall surface 147B of the locking groove 143a of the third-speed and fourth-speed drive gears 143, 144. The third-speed and fourth-speed drive gears 143 and 144 are pressed toward the main shaft 122 by the fork side end 173b, and the rotation thereof is decelerated. When the rotation of the third-speed and fourth-speed drive gears 143 and 144 is decelerated, the rotation of the main shaft 122 rotating integrally is decelerated, and the rotation of the first-speed drive gear 141 rotating integrally with the main shaft 122 Is also slowed down. The first-speed drive gear 141 meshes with the first-speed driven gear 151, and the rotation of the first-speed driven gear 151 is decelerated.

  When the shift drum 80 further rotates, the steel ball 180 is housed inside the recess 178 by the coil spring 179 that has lost the pressing force from the projection 190, and the projection 190 moves the steel ball 180 into the recess 178. Move while pushing. During this time, the third-speed and fourth-speed drive gears 143 and 144 are kept pressed against the main shaft 122 by the fork side end 173b.

  Further, when the shift drum 80 rotates in the reverse direction SD and is in the first speed dog tooth engagement position A1, the steel ball 180 is housed inside the recess 178 by the protrusion 190, and the first speed driven gear 151 Deceleration continues. Therefore, the differential rotation between the fifth-speed driven gear 155 and the first-speed driven gear 151 (the counter shaft 150 is not rotated) is reduced, and the shifter-side dog teeth Gsd of the fifth-speed driven gear 155 While the generation of the hitting sound at the time of engagement with the driven free side dog teeth Gfd is suppressed, the hitting sound can be reduced.

As described above, the inner surface 173bB of the fork side end 173b of the first shift fork 173 is provided with the rough surface portion 177 having a high frictional resistance, and the locking grooves 143a of the third and fourth speed drive gears 143 and 144 are provided. The bottom wall surface 147B is provided with a rough surface portion 148 having a high frictional resistance, so that the above-described deceleration action can be efficiently performed.
In the present embodiment, the rough surface portions 48 and 77 are provided so as to oppose each other on both the fork side end portion 173b and the locking groove 143a. An effect can be obtained. Further, the rough surface portion 77 may be provided only on the inner side surface 73bB of the fork side end portion 73b2 on the side pressed against the locking groove 143a in the inner side surface 73bB of the fork side end portion 173b.

The fourth embodiment of the present invention described above has the following effects.
Of the lead grooves 81, the bottom wall surface 182B of the first lead groove 183 with which the pin portion 173c of the first shift fork 173 is engaged is located radially outward of the shift drum 80 from the center C183 in the width direction of the bottom wall surface 182B. A protrusion 190 is provided so as to protrude toward the surface. And the protrusion 190 is arrange | positioned so that the top part 190a may be located between the neutral position Pn of the 1st lead groove 183 to the 1st-speed dog-tooth engagement position A1.
Further, a recess 178 in which the coil spring 179 and the steel ball 180 are accommodated is formed on the lead groove side end surface 173d of the pin portion 173c of the first shift fork 173. The steel ball 180 is formed along the recess 178 with the coil spring 171. And is pressed against the bottom wall surface 182B of the first lead groove 183.

  According to the above configuration, before the shifter-side dog tooth Gsd of the fifth-speed driven gear 155 is engaged with the free-side dog tooth Gfd of the first-speed driven gear 151 during the shift-up operation from the neutral position Pn to the first-speed position P1. The projecting portion 190 presses the pin portion 173c of the first shift fork 173 in the reverse direction SD of the shift drum 80 via the steel ball 180, so that the first shift fork 173 is centered on the shift fork shaft 71. The shift drum 80 rotates in a direction SU opposite to the rotation direction of the shift drum 80, and the fork side end 173b of the first shift fork 173 is pressed against the bottom wall surface 147B of the locking groove 143a of the third and fourth speed drive gears 143 and 144. Thus, the rotation of the main shaft 140 is decelerated, and the rotation of the first-speed driven gear 151, which is the next shift stage, is decelerated, thereby reducing the differential rotation between the fifth-speed driven gear 155 and the first-speed driven gear 151, and the fifth-speed driven Gear 155 shifter side dog tooth Gsd and first speed driven It can be a free-side dog teeth Gfd of A 151 to suppress the generation of striking sound at the time of engagement.

  A recess 178 that is recessed in a cylindrical shape toward the shift fork shaft 71 along the radial direction of the shift drum 80 is formed on the lead groove side end surface 173d of the pin portion 173c of the first shift fork 173. The coil spring 179, which is an elastic member, and the steel ball 180, which is a ball member, are accommodated. The first shift fork 173 is rotated about the shift fork shaft 71 via the steel ball 180. When a pressure equal to or higher than a predetermined pressure is applied to the steel ball 180, the coil spring 179 contracts, so that the first shift fork 173 The pin portion 173c is not caught by the protrusion 190, and the smooth rotation of the shift drum 80 can be maintained.

  A rough surface portion 177 is provided on the inner side surface 173bB of the fork side end 173b of the main side shift fork 173. A rough surface portion 148 is provided on the bottom wall surface 147B of the locking groove 143a of the third-speed and fourth-speed drive gear 44. During the upshifting operation of the transmission 21, the inner side surface 173bB of the fork side end 173b of the first shift fork 173 is engaged with the locking grooves of the third-speed and fourth-speed drive gears 143, 144 via the rough surface portions 148, 177. It is possible to increase the frictional force when pressed against the wall surface 147B of 143a, and to efficiently reduce the rotation of the main shaft 122. Then, it becomes possible to reduce the differential rotation by decelerating the rotation of the first speed driven gear 151 that is the next shift stage, and the generation of the hitting sound when the shifter side dog teeth Gsd and the free side dog teeth Gfd are engaged. Can be suppressed.

  In the fourth embodiment, the shape of the protrusion 190 is not limited to a hemispherical shape, and can be changed within a range that does not depart from the spirit of the present invention, such as a pyramidal shape or a cubic shape.

  Further, similarly to the modification of the second embodiment, the recess 178 may not be formed on the lead groove side end surface 173d of the pin portion 173c of the first shift fork 173.

  In this embodiment, the pedal type transmission 21 in which the shift pedal 97 is provided on the shift spindle 97 is used. However, as in the second embodiment, an electric type using a shift motor 99 is used. The transmission 21 may be used.

  Further, in the fourth embodiment, the protrusion 190 is configured so that the pin portion 173c of the main shift fork 173 is connected to the main lead groove 183 in accordance with the rotation of the shift drum 80 when the transmission 21 is shifted up. In the middle of moving from the neutral position Pn to the first speed position P1, which is the next gear position, the shifter side dog teeth Gsd of the shift gear Gs of the next speed stage and the free side dog of the free gear Gf are guided by this pattern. The pin portion 173c may be pressed until the dog tooth engagement position A where the tooth Gfd engages is reached, and the position of the top portion 190a is not limited to the position of the present embodiment.

  As mentioned above, although embodiment of this invention was described with reference to drawings, embodiment is not restricted to the content of said description, In the range which does not deviate from the meaning of this invention, it can change.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 20 ... Variable speed drive mechanism, 22 ... Main axis, 23 ... Odd-numbered stage main axis (first main axis), 24 ... Even-numbered stage main axis (second main axis), 25 ... Counter axis, 43 ... Odd number Step drive shifter gear (third speed drive gear), 43a ... locking groove, 44 ... Even step drive shifter gear (fourth speed drive gear), 44a ... locking groove, 47 ... wall surface, 47B ... bottom wall surface, 47L ... left wall surface, 47R ... Right wall surface 48 ... Rough surface 49 ... Stopper plate 55 ... Driven shifter gear (5-speed driven gear) 55a ... Locking groove 56 ... Driven shifter gear (six-speed driven gear) 56a ... Locking groove 60 ... Hydraulic Clutch, 61A ... odd-numbered hydraulic clutch (first hydraulic clutch), 61B ... even-numbered hydraulic clutch (second clutch), 63 ... clutch outer, 70 ... change mechanism, 71 ... shift fork shaft, 72 ... shift fork, 72c ... 72A ... Main side shift fork, 72B ... Counter side shift fork, 73 ... Odd Stage main side shift fork (first shift fork), 73b ... Fork side end, 73bB ... Inner side, 73bR ... Right side, 73c ... Lead groove side end (pin part), 74 ... Even stage main side shift fork ( Second shift fork), 74b ... Fork side end, 74bB ... Inner side, 74bL ... Left side, 74c ... Lead groove side end (pin part), 77 ... Rough surface, 80 ... Shift drum, 80c ... Outer surface, 81 ... Lead groove, 81A ... Main side lead groove, 82 ... Wall surface, 82L ... Side wall surface (left wall surface), 82R ... Side wall surface (right wall surface), 83 ... Odd-numbered main side lead groove (first lead groove), 84 ... Even-numbered main side lead groove (second lead groove), 89 ... Projection arrangement lead groove, 90 ... Projection, 100 ... Recess, 101 ... Elastic member, 102 ... Ball member, 110 ... Projection, 120 ... Projection 122 ... Main shaft 125 ... Counter shaft 141 ... Drive fixed gear (first speed drive gear) 142 ... Drive fixed gear ( (Speed drive gear), 143 ... drive shifter gear (three-speed drive gear), 143a ... locking groove, 148 ... rough surface, 155 ... driven shifter gear (fifth speed driven gear), 155a ... locking groove, 156 ... driven shifter gear (six (Speed driven gear), 156a ... locking groove, 160 ... hydraulic clutch, 172 ... shift fork, 172c ... lead groove side end (pin part), 173 ... main side shift fork (first shift fork), 173b ... fork side End portion, 173bB ... Inner surface, 173c ... Lead groove side end (pin portion), 174 ... Counter side shift fork, 177 ... Rough surface portion, 178 ... Recess, 179 ... Elastic member, 180 ... Ball member, 181 ... Lead groove , 182 ... wall surface, 182B ... bottom wall surface, 183 ... main side lead groove, 190 ... projection, Gf ... free gear, Gs ... shifter gear, Gfd ... free side dog tooth, Gsd ... shifter side dog tooth, M ... drive gear, C: Driven gear, Mo: Odd stage drive gear, Me: Even stage drive Dynamic gear,

Claims (10)

A main shaft (22, 122) on which a plurality of drive gears (M) are supported, and a hydraulic pressure connected to the main shaft (22, 122) to intermittently transmit the rotational driving force from the crank shaft (7). A constantly meshing transmission (21) comprising a clutch (60, 160) and a counter shaft (25, 125) on which a plurality of driven gears (C) meshing with the drive gear (M) are supported; ,
A shift drum (80) that is rotated during the shifting of the transmission (21) and is provided with a plurality of lead grooves (81, 181) on its radially outer circumferential surface (80c); and the shift drum (80), A shift fork shaft (71) whose axes are arranged in parallel and a plurality of the lead grooves (81, 181) of the shift drum (80) are respectively engaged and guided in the axial direction of the shift fork shaft (71). A change mechanism (70) comprising a plurality of shift forks (72, 172),
The driving gear (M) and the driven gear (C) are arranged so as to rotate integrally with the shafts (22, 25, 122, 125) on which they are supported and are movable in the axial direction, and are orthogonal to the axial direction. The shifter gears (Gs) having shifter side dog teeth (Gsd) formed on the surface and the shafts (22, 25, 122, 125) supported by the respective shifter gears (Gsd) are rotatable relative to each other and are fixed so as not to move in the axial direction. A free gear (Gf) on which a shifter side dog tooth (Gsd) and a free side dog tooth (Gfd) that are detachably opposed are formed,
The shift forks (72, 172) are locked in locking grooves (43a, 44a, 55a, 56a, 143a, 155a, 156a) formed in the shifter gear (Gs),
As the shift drum (80) rotates, the shift forks (72, 172), which are guided in the lead grooves (81, 181) and move in the axial direction, move the shifter gear (Gs) to shift the shifter side dog. In the transmission drive mechanism (20) of the internal combustion engine (1) for shifting the transmission (21) by engaging the teeth (Gsd) with the corresponding free-side dog teeth (Gfd),
Of the lead grooves (81, 181), the lead groove side ends (72c, 172c) of the shift forks (72, 172) for moving the shifter gear (Gs) supported by the main shafts (22, 122) The wall surface (82, 182) of the main side lead groove (81A, 183) with which the main body is engaged projects from the wall surface (82, 182) toward the inside of the main side lead groove (81A, 183). Protrusions (90, 110, 120, 190) are provided, and when the transmission (21) is shifted up, the protrusions (90, 110, 120, 190) are connected to the main-side lead grooves (81A, 183). The shift fork (72, 172) guided to the lead groove side end (72c, 172c) is pressed so that the shifter side dog teeth (Gsd) of the shifter gear (Gs) of the next shift stage are pressed. Before engaging the free side dog teeth (Gfd) of the corresponding free gear (Gf), the shift forks (72, 17) guided in the main side lead grooves (81A, 183). 2) is temporarily inserted into the locking grooves (43a, 44a, 143a) of the shifter gear (Gs) supported by the main shaft (22, 122) by the protrusions (90, 110, 120, 190). The speed change drive mechanism (20) of the internal combustion engine (1) characterized in that the rotation of the main shaft (22, 122) is decelerated to decelerate the rotation. The main shaft (22) is composed of an odd-numbered main shaft (23) and an even-numbered main shaft (24),
The hydraulic clutch (60) includes an odd-numbered hydraulic clutch (61A) coupled to the odd-numbered main shaft (23), an even-numbered hydraulic clutch (61B) coupled to the even-numbered main shaft (24), A clutch outer (63) for supplying rotational driving force from the crankshaft (7) to the odd-numbered hydraulic clutch (61A) and the even-numbered hydraulic clutch (61B);
The drive gear (M) includes an odd-numbered drive gear (Mo) supported by the odd-numbered main shaft (23) and an even-numbered drive gear (Me) supported by the even-numbered main shaft (24). Have
The shifter gear (Gs) includes an odd-numbered stage shifter gear (43) disposed in the odd-numbered stage drive gear (Mo) and an even-numbered stage shifter gear (44) disposed in the even-numbered stage drive gear (Me). Driving shifter gears (43, 44) for driving, and driven shifter gears (55, 56) disposed on the driven gear (C),
The shift fork (72) includes the odd-numbered main shift fork (73) locked in the locking groove (43a) of the odd-numbered drive gear (Mo) and the engagement of the even-numbered drive gear (Me). The main-side shift fork (72A) having an even-numbered main-side shift fork (74) locked to the stop groove (44a) and the locking grooves (55a, 56a) of the driven gear (C) Counter-side shift fork (72B)
A fork side end (73b) of the odd-numbered main shift fork (73) is locked in the locking groove (43a) of the odd-numbered drive shifter gear (43),
A fork side end (74b) of the even-numbered main shift fork (74) is locked in the locking groove (44a) of the even-numbered drive shifter gear (44),
The main-side lead groove (81A) includes an odd-numbered main-side lead groove (83) engaged with an end portion (73c) of the odd-numbered main-side shift fork (73) and the even-numbered-stage main-side An even-numbered main-side lead groove (84) with which the lead groove-side end (74c) of the shift fork (74) is engaged,
At least one of the odd-numbered-stage main-side lead groove (83) and the even-numbered-stage main-side lead groove (84) is a protrusion-positioned lead groove (89) provided with the protrusions (90, 110),
The lead groove of the main shift fork (72A) in which the protrusion (90, 110, 120) is engaged with the protrusion-positioned lead groove (89) during a shift-up operation of the transmission (21). By pressing the side end portions (73c, 74c), the fork side end portions (73b, 74b) of the main side shift fork (72A) are moved to the fork side by the protrusions (90, 110, 120). The end portions (73b, 74b) are temporarily pressed into the locking grooves (43a, 44a) to be locked to support the shifter gear (Gs) in which the locking grooves (43a, 44a) are formed. The speed change drive mechanism (20) of the internal combustion engine (1) according to claim 1, wherein the rotation of the main shaft (22) is decelerated.   The protrusion (90) is provided so as to protrude from a side wall surface (82L, 82R) of the main-side lead groove (81A) in an axial direction of the shift drum (80). A speed change drive mechanism (20) of the internal combustion engine (1) according to 2.   In the axial direction of the main shaft (22), the fork side end portions (73b, 74b) of the main side shift fork (72A) on the side of the drive shifter gear (43, 44) are pressed. On the side, a stopper plate (49) for restricting the axial position of the drive shifter gear (43, 44) is disposed adjacent to the drive shifter gear (43, 44). Item 5. A variable speed drive mechanism (20) for an internal combustion engine (1) according to item 3. The protrusions (90, 110, 120) are provided so as to protrude radially outward of the shift drum (80) from the bottom wall surface (82B, 182B) of the main-side lead groove (81A, 183). The speed change drive mechanism (20) of the internal combustion engine (1) according to claim 2, wherein the speed change drive mechanism (20) is provided. The lead groove side end portion (73c, 74c) of the main side shift fork (72A) pressed by the protrusion (90, 120) has a recess (100) along the radial direction of the shift drum (80). The recess (100) includes an elastic member (101) and a ball member (102) that is pressed against the bottom wall surface (82B) of the main-side lead groove (81A) by the elastic member (101). The speed change drive mechanism (20) of the internal combustion engine (1) according to claim 5, wherein The shift fork (172) has a main shift fork (173) locked to the drive gear (M) and a counter shift fork (174) locked to the driven gear (C). ,
The shifter gear (Gs) includes a drive shifter gear (143) supported by the main shaft (122) and a driven shifter gear (155, 156) supported by the counter shaft (125).
A fork side end (173b) of the main side shift fork (173) is engaged with the locking groove (143a) of the drive shifter gear (143),
The drive gear (M) has drive fixed gears (141, 142) that rotate integrally with the main shaft (122) and are fixed so as not to move in the axial direction.
The protrusion (190) extends from the bottom wall surface (182B) of the main lead groove (183) to which the lead groove end (173c) of the main shift fork (173) is engaged with the shift drum ( 80) is provided to protrude outward in the radial direction,
During the shift-up operation of the transmission (21), the protrusion (190) presses the lead groove side end (173c) of the main side shift fork (173), so that the main side shift fork ( 173) is forcibly pressed against the locking groove (143a) of the drive shifter gear (143) than usual by the protrusion (190), and the main shaft (122). The speed change drive mechanism (20) of the internal combustion engine (1) according to claim 1, wherein the rotation speed of the internal combustion engine (1) is reduced. A concave portion (178) along the radial direction of the shift drum (80) is formed in the lead groove side end portion (173c) of the main side shift fork (173) pressed against the protrusion (190), The recess (178) accommodates an elastic member (179) and a ball member (180) that is pressed against the bottom wall surface (182B) of the main-side lead groove (183) by the elastic member (179). The variable speed drive mechanism (20) of the internal combustion engine (1) according to claim 7, characterized in that: Of the fork side end portions (72b, 172b) which are the end portions of the shift forks (72, 172) guided by the main side lead grooves (81A, 183) on the side locked by the shifter gear (Gs) Of the surfaces (73bR, 74bL, 73bB, 74bB, 173bB) pressed against the shifter gear (Gs) or the wall surfaces (47, 147) of the locking grooves (43a, 44a, 143a) of the shifter gear (Gs), A rough surface portion (48, 77, 148, 177) having a high frictional resistance is provided on at least one of the surfaces (47B, 47L, 47R, 147B) against which the fork side end portions (72b, 172b) are pressed. A variable speed drive mechanism (20) for an internal combustion engine (1) according to any one of claims 1 to 8.   The protrusions (90, 110, 120, 190) are located at the first speed position (P1n, P1) from the neutral position (Pnn, Pn) of the transmission (21) in the main side lead groove (81A, 183). When the shift drum (80) is pivoted to the main lead groove (81A, 183), the lead fork end (72c, 172c) of the shift fork (72, 172) is guided to the main lead groove (81, 183). The variable speed drive mechanism (20) of the internal combustion engine (1) according to any one of claims 1 to 9, wherein the variable speed drive mechanism (20) is provided in the middle of being guided and moved by the side lead grooves (81A, 183). .

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