JP2003247643A - Powered vehicle transmission - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To control overshift of a speed change shaft with a simple configuration. A standard four-wheel drive state of front-rear wheel drive in which a rotational peripheral speed of a front wheel is substantially the same as a rotational peripheral speed of a rear wheel from a drive source via a transmission system in a transmission case; A transmission that can be switched in accordance with the turning operation of the vehicle body is provided in a front wheel speed-up state in which the rotational peripheral speed of the front wheel 14 is higher than the rotational peripheral speed of the rear wheel 15, and the transmission is provided in the axial direction. A transmission shaft 80 that moves at a predetermined interval and a stepped transmission mechanism (gears 72, 73, 76, 77) provided around the transmission shaft 80.
), And an engagement mechanism (key shift claw 70, locking grooves 72a, 73a, etc.) that expands and contracts when the transmission shaft 80 moves. Further, the transmission shaft 80 is provided at one end or the other end of the transmission shaft 80.
A restricting member (protrusion 55) for restricting the movement of the
a, 80a, 90a).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power vehicle such as a tractor and a riding lawn mower.

[0002]

2. Description of the Related Art While a tractor or the like is running in a field,
In order to swivel around the ridge quickly and with a small radius,
A tractor in which a speed increasing device is incorporated in a front wheel drive system of a power vehicle is known. This speed increasing device is usually composed of a switching device capable of shifting between high speed and low speed, and switching between high speed and low speed is interlocked with operation of a steering wheel. Then, when traveling straight ahead, the speed increasing device is switched to the low speed side to enter the standard four-wheel drive state in which the rotational peripheral speeds of the front wheels and the rear wheels are substantially equal, and when turning, the speed increasing device is switched to the high speed side and the front wheels are rotated. The rotational peripheral speed is switched to the front wheel speed increasing state in which the rotational peripheral speed is about twice as high as the rotational peripheral speed of the rear wheels. Switching of the speed increasing device may be performed by a hydraulic clutch,
Many low-priced tractors change the shifter mechanically.

[0003]

By the way, when the high speed / low speed switching portion of the front wheel speed increasing device of the front wheel drive system of the power vehicle is mechanically operated to shift gears, if the gear shifting operation portion is loose, the gear shifting operation is performed. May be delayed, which causes a problem that a smooth turning operation cannot be performed. Especially when the shifting part is composed of a key shift device, not only is there a delay in shifting operation, but also if the disengagement load during shifting is increased, a large impact is generated at the moment when the key shift pawl in the power-connected state is disengaged from the shifting gear. There was a problem that sound was generated. The impact sound causes the shift shaft to be overshifted when the shifting portion shifts through the key shift device, and the key shift claws disengage from the locking groove at the target stop position of the shifting shaft and try to enter the other locking groove side. There is also a cause.

Therefore, an adjustment unit is separately provided for each of the links, levers, etc., which are associated with the transmission shaft, so that the operating dimensions are always adjusted so that the transmission shaft does not overshift. However, since the variation of these members is large and the number of them is large, the adjustment work requires man-hours.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transmission device for a power vehicle capable of restricting an overshift of a transmission shaft with a simple structure.

Further, the applicant has already filed a patent for the standard four-wheel drive state of the front wheel drive system of the power vehicle and the operation of the switching portion of the front wheel speed increasing device by means of an electric motor (Japanese Patent Application No. 2000-242242).
2001-235880). However, when the power vehicle is a tractor, the rear part is equipped with a working machine such as a rotary tiller, so when the front wheel speed increasing device is selected, the tractor turns quickly, so the working machine is It may not be possible to follow the turning mode.

Therefore, an object of the present invention is to provide a transmission device for a power vehicle which can always hold a rear working machine in a raised position when a front wheel speed increasing device is selected.

[0008]

The above-mentioned problems of the present invention can be solved by the following technical means. That is, claim 1
In the invention, the front and rear wheel drive standard four-wheel drive state in which the rotational peripheral speed of the front wheels 14 is substantially the same as the rotational peripheral speed of the rear wheels 15 from the drive source 2 via the transmission system in the mission case 3, A power vehicle having a transmission that can be switched to a front-wheel speed-up state in which the rotational peripheral speed of the front wheels 14 is higher than the rotational peripheral speed of the rear wheels 15 according to the turning motion of the vehicle body. A speed change shaft 80 that moves a predetermined distance in the axial direction and a stepped speed change mechanism (gear 72, 73,
76, 77) and an engaging mechanism (key shift claw 70, locking grooves 72a, 73a, etc.) that expands and contracts when the speed change shaft 80 moves, and further on one end side or the other end side of the speed change shaft 80,
A speed change device for a power vehicle, comprising: a restricting member that restricts a movement of a speed change shaft 80 over a predetermined interval.

According to the first aspect of the present invention, since the restricting member for restricting the movement of the speed change shaft 80 over the predetermined distance is provided at one end side or the other end side of the speed change shaft 80, the speed change shaft 80 is over-operated. Even if an attempt is made to shift, overshift of the shift shaft in at least one direction can be restricted.

The invention according to claim 2 is the transmission device for a power vehicle according to claim 1, wherein the restriction member is adjustable from the outside of the machine body. According to the invention of claim 2,
Since the regulation member can be easily adjusted from the outside of the aircraft,
It is possible to easily adjust the play of the speed change shaft 80.

Further, according to the third aspect of the present invention, the front and rear wheels are driven such that the rotational peripheral speed of the front wheels 14 is substantially the same as the rotational peripheral speed of the rear wheels 15 from the drive source 2 via the transmission system in the mission case 3. The standard four-wheel drive state and the front wheel speed increasing state in which the rotation peripheral speed of the front wheels 14 is higher than the rotation peripheral speed of the rear wheels 15 are provided with a transmission that can be switched with the turning operation of the steering wheel 16 of the vehicle body. A power vehicle that has a work machine 113 and a hydraulic control circuit 120 that controls the work machine 113 to move up and down, and the transmission is
A speed change shaft 80 that moves a predetermined distance in the axial direction and a stepped speed change mechanism (gears 72, 73, 76,) provided around the speed change shaft 80.
77)) and an engagement mechanism (key shift claw 70, locking grooves 72a, 73a, etc.) that expands and contracts when the speed change shaft 80 moves, and further, an actuator (electrically operated) that operates in conjunction with the turning operation of the steering handle 16. The motor 111 and the actuator 124) are provided, and the actuator and the speed change shaft 80 are interlockingly connected with each other through a connecting tool.
3 is a transmission of a power vehicle including control means for raising 3;

According to the third aspect of the present invention, when the shift position of the shift shaft 80 is selected by the actuator to be the front wheel speed increasing state, the rear working machine 113 can be interlocked and raised via the control means.

[0013]

According to the invention of claim 1, the length of the speed change shaft 80 in the axial direction is accurately created, so that the speed change shaft 80 can be obtained.
Of the speed change shaft 80 for restricting the movement of the gears over a predetermined interval.
Even if the shift shaft 80 is to be overshifted when the shift shaft 80 is operated, the shift member can be restrained from overshifting only by disposing the shift shaft at one end side or the other end side.

As a result, as in the prior art, many external links, levers, motors, etc., which are separately provided as members, are used as overshift restricting members of the speed change member (speed change shaft 80), so that each of them can be used. This can be more easily regulated as compared with the case where the components are adjusted in position and then mounted as a mission case of a power vehicle.

According to the invention of claim 2, since the regulating member has the structure of the transmission of the power vehicle according to claim 1 which can be easily adjusted from the outside of the machine body, after being mounted as a mission case of the power vehicle, it can be externally adjusted. Since the backlash of the speed change shaft 80 can be removed and adjusted, the adjustment work can be easily performed in a short time.

According to the third aspect of the present invention, when the actuator selects the gear shift position of the gear shift shaft 80 to be the front wheel speed increasing state at the time of turning, the rear working machine 113 is raised by interlocking with the control means. Therefore, there is no risk that the working machine will come into contact with other objects and cause a failure, and the powered vehicle can be smoothly turned.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a side view of a tractor according to an embodiment of the present invention, FIG. 2 shows an enlarged sectional view of a circle A portion of FIG. 1, and FIG. 3 shows a modification of FIG. In FIG. 4, FIG.
5 is a side sectional view of the tractor inside the transmission case, FIG. 5 is an enlarged side sectional view of a double-speed case portion that is a main part attached to the front end of the transmission case of the tractor of FIG. 1, and FIG. 6 is an enlarged side of the transmission portion of FIG. A sectional view is shown.

A conventionally known tractor 1 has an engine 2 mounted on a front portion of a machine body, and transmits rotational power of the engine 2 to a mission case 3. In the illustrated example, as shown in FIG. 1, between the rear wall of the engine 2 and the front wall of the mission case 3, a saddle-shaped case 13 having a lower open cross-section, which is a support frame, is attached to connect the two. . Further, a main clutch case 18 having a main clutch, transmission gears, and the like installed therein is attached to a rear surface portion of the lower space of the saddle type case 13 on the engine 2 side, and a main clutch case 18 having a main clutch, a transmission gear, and the like is attached to a front surface portion of the lower space of the saddle type case 13 on a mission case 3 side. , Double speed case 8 is attached.

Then, the driving force of the engine 2 is transmitted from the upper portion of the double speed case 8 attached to the front end of the transmission case 3 to the input shaft 4 projecting forward through the connecting shaft 17. The main transmission 5 and the sub transmission 6 are provided in the mission case 3. The specific structure of the mission case 3 will be described later.

A hydraulic cylinder case 9 is attached to the upper rear portion of the transmission case 3, and lift arms 10 and 10 are rotatably and pivotally attached to both right and left sides of the hydraulic cylinder case 9.

Lift arms 10, 10 and lower link 1
Lift rods 12 and 12 are provided between the upper link 1 and the lower link 11 and the lower link 11 and 1.
A working machine is connected to the rear end of the working machine 1, and when the lift arms 10 and 10 are rotated, the working machine (not shown) moves up and down.

Next, the power transmission system of the tractor 1 will be described with reference to FIG. A transmission shaft 34 is rotatably mounted on the rear portion of the input shaft 4. A gear 35 is provided at the rear end of the input shaft 4, and the front end of the speed change shaft 34 projects into a recess provided in the direction of the shaft center of the gear 35.
No. 4 needle bearing 37 is supported. Two main transmission gears 38, 39 and one auxiliary transmission gear 40 are spline-fitted on the transmission shaft 34 so as to be movable back and forth.

The main transmission gear 38 has a two-stage gear structure consisting of a small-diameter gear 38a and a large-diameter gear 38b. The main transmission gear 39 behind it is composed only of the large-diameter gear 39a, and the sub-transmission gear 40 behind it. Is a large diameter gear 40a and a small diameter gear 4
It has a two-stage gear configuration of 0b.

A pinion drive shaft 42 having a pinion gear 41 at its rear end is provided below the speed change shaft 34, and a two-stage gear 44 meshing with the sub speed change gear 40 is provided at the rear of the pinion drive shaft 42. Are integrally formed with the shaft 42. The two-stage gear 44 is a small diameter gear 44 on the front side.
a, a large diameter gear 44b is provided at the rear part,
When the large-diameter gear 40a of 0 meshes with the small-diameter gear 44a of the two-stage gear 44, "high speed H" of the sub-transmission is obtained, and the sub-transmission gear 40 is slid backward so that the sub-transmission gear 40 has a small-diameter gear 40b.
When the gear meshes with the large-diameter gear 44b of the two-stage gear 44, the "low speed L" of the auxiliary shift is obtained.

The cylinder shaft 45, which is rotatably fitted and supported on the pinion drive shaft 42, is provided with gears 45a and 45b on its outer circumference in the middle and at the rear. Also,
A spline groove is formed in a front portion of the cylinder shaft 45 over a predetermined length, and two gears 47 and 48 are attached to the spline groove. The two gears 47 and 48 are integrated with the cylinder shaft 45. It is configured to rotate.

The gear 47 meshes with the gear 35 at the rear portion of the input shaft 4 and transmits the rotation of the input shaft 4 to the cylindrical shaft 45. Gear 4
8 meshes with the small-diameter gear 38a of the main transmission gear 38 to move to the third forward speed, and the large-diameter gear 38b of the main gear 38 has the gear 45 of the cylinder shaft 45.
When it meshes with a, it becomes the second forward speed, and the gear 45b of the cylinder shaft 45
When the gear meshes with the large diameter gear 39a of the main transmission gear 39, it moves forward 1
High speed is obtained, and further, the auxiliary transmission gear 40 which is in the rear position of its transmission
By sliding forward and backward, you can obtain two high and low speeds,
The combination of the gears and the two auxiliary gears is configured to give a total of 6 forward speeds to the pinion gear 41. The pinion gear 41 meshes with the side gear 43 of the rear wheel differential device and drives the rear wheel 15.

The driving force input to the input shaft 4 causes the cylinder shaft 45 to constantly rotate via the gear 35 when the main clutch is engaged. In addition, the gear 45b of the cylinder shaft 45 is not
When the large-diameter gear 39a is engaged, the transmission shaft 34 moves forward 1
Rotate at high speed. Further, the auxiliary transmission gear 4 at the rear end of the transmission shaft 34
When 0, the power is not transmitted in the disengaged state, and the pinion drive shaft 42 rotates when either of the auxiliary gears 40a and 40b meshes with the two-stage gears 44a and 44b. When the pinion drive shaft 42 rotates, the pinion gear 41 at the rear end of the shaft rotates.

Further, the gear 45a of the cylinder shaft 45 is always meshed with the back gear 50 on the back idle shaft 49, and the gear shift shaft 34 can be reversed by meshing the main gear 39 on the rear side with the back gear 50. it can. In this case, by sliding the auxiliary transmission gear 40 back and forth, two shift speeds can be obtained, and thus two speeds are provided to the pinion gear 41 as the reverse speed.

The relationship between the operating lever 51 for operating the main transmission device 5, the operating lever 52 for operating the auxiliary transmission device 6, and the main transmission gears 38, 39 and the auxiliary transmission gear 40 will be omitted. The main shift lever 51 operates the lever 51 according to a conventionally known H-shaped pattern in the cockpit to operate the two main shift gears 38 and 39. On the other hand, the sub-transmission lever 52 adopts a form in which it is moved back and forth along an I-shaped pattern in a conventionally known cockpit.

A PTO drive shaft 55 is mounted below the pinion drive shaft 42, a PTO two-step gear 56 is spline-fitted to the front portion of the PTO drive shaft 55, and a large diameter is provided behind it. The gear 57 is attached to the PTO drive shaft 55 in an idling manner.

Two-stage gear 56 for PTO and the large diameter gear 57
Clutch claws 58 and 59 are respectively provided at the opposite positions of the cylinder. When the two-stage gear 56 for PTO is slid backward to engage the clutch claw 58 and the clutch claw 59 of the large-diameter gear 57, P from the gear 45b through the large diameter gear 57
The rotation of the first speed TO is transmitted to the PTO drive shaft 55 via the clutch pawls 59 and 58. Also, two-stage gear for PTO 5
When the large diameter gear 56b of No. 6 is meshed with the gear 45a of the cylinder shaft 45, the second speed of the PTO is obtained, and the small diameter gear 56a of the two-stage gear 56 is changed.
When the gear is engaged with the gear 48 on the cylinder shaft 45, the PTO third speed becomes P
It is transmitted to the TO drive shaft 55. PTO drive shaft 5
The rotation of the PTO drive shaft 55 is transmitted to the PTO shaft 63 by the meshing of both gears 60, 61 of the gear 60 provided on the rear part of the gear No. 5 and the gear 61 attached to the PTO shaft 63.

Next, the front wheel drive system will be described with reference to FIG. A reverse PT is provided at the front of the pinion drive shaft 42.
A two-stage gear 64 for O is loosely fitted, and a power take-off gear 65 for driving front wheels is spline-fitted to the front part thereof. A large-diameter gear 67 pivotally supported by a bearing 66 is meshed with the power take-out gear 65, and the large-diameter gear 67 has a tubular portion 67a integrally formed with the gear 67 and extending forward.
A groove 71 into which a key shift claw 70, which will be described later, can be inserted and removed radially outward is formed in the cylindrical portion 67a in the front-rear direction, and two gears 72 and 73 are loosely fitted on the outer periphery of the cylindrical portion 67a. Has been done. These two gears 72, 73 are provided with a plurality of locking grooves 72a, 73a on their inner peripheral portions, respectively, and the tip end portion of the key shift claw 70 projects outward from the groove 71 of the tubular portion 67a, and the gears 72, 73 are formed. When any one of the locking grooves 72a and 73a of the
2 or gear 73.

The small-diameter gear 72 and the large-diameter gear 73 are gears 76, 7 on a front-wheel drive shaft 75 which is hung around them.
It always meshes with 7. When the key shift claw 70 enters the locking groove 72a of the small-diameter gear 72, low-speed rotation is transmitted to the front wheel drive shaft 75, and the front wheel 14 enters a standard four-wheel drive state in which the peripheral speed of the rear wheel 15 is substantially the same. 70 is a large-diameter gear 7
When entering the engagement groove 73a of No. 3, high-speed rotation is transmitted to the front-wheel drive shaft 75, and the front wheel 14 is switched to a front-wheel speed-up state in which the front wheel 14 is rotated at a speed about twice as fast as the peripheral speed of the rear wheel 15. The collars 78 and 79 position the two gears 72 and 73. A locking groove 78a for accommodating the key shift claw 70 is provided on the inner peripheral portion of the front collar 78. When the key shift claw 70 is inserted into the locking groove 78a, the rotational power of the large diameter gear 67 is applied to the front wheel drive shaft 75. It is not transmitted and becomes neutral. At this time, only the rear wheels 15 are in a two-wheel drive state.

The switching between the standard four-wheel drive state and the front wheel speed-up state is performed by an interlocking mechanism which is interlocked with the operation of the steering wheel 16. That is, when traveling straight ahead, the vehicle travels in the standard four-wheel drive state, and when the steering wheel 16 is steered by a predetermined angle or more, it is measured by a steering angle sensor, which will be described later, and is switched to the front wheel speed increasing state to make a small turn.

Further, the speed change shaft 8 for supporting the key shift claw 70
The front part of 0 is provided with a recess 84 into which the locking pin 83 of the shifter arm 82 can be inserted.
It can rotate about 6 times.

A slit is provided in the rear half of the transmission shaft 80 in the radial direction, and two key shift claws 7 are provided in this slit.
0 and 70 are pivotally supported by pins 87 and 87, and a spring 88 is interposed between the two key shift claws 70 and 70 so that the two key shift claws 70 and 70 are always urged outward in the radial direction. I have to.

A lid 90 is attached to the front portion of the mission case 3 via a boss 89 with bolts 91, 91, and a projection for restricting the shift stroke amount of the shift shaft 80 is provided on the back side of the lid 90. 90a is provided to prevent the key shift claw 70 from being disengaged from the engagement groove 73a of the large diameter gear 73 when the transmission shaft 80 is switched from the standard 4WD state to the speed increasing side.

Further, by providing a projection 80a serving as a position regulating member also on the rear end of the speed change shaft 80, the key shift pawl 70 has a small diameter due to overshift even when the speed increasing side is switched to the standard 4WD state. The gear 72 is regulated so as not to come out of the locking groove 72a. Instead of the protrusion 80a, the protrusion 55a may be provided on the side of the PTO drive shaft 55 that faces the speed change shaft 80 as shown in the circle A of FIG.

As described above, by merely adjusting the lengths of the projection 80a and the projection 90a in advance when the transmission shaft 80 is attached, it is possible to prevent overshifting of the transmission shaft 80 in either the front or rear direction.

Therefore, the transmission shaft 8 in the mission case 3
By precisely adjusting and manufacturing 0 itself, overshift can be regulated without adjustment when the mission case 3 is mounted on a tractor. For example, even after the assembling, if the lid 90 is removed, it is possible to easily change the thickness of the protrusion 90a and attach it again. Although not shown, if the protrusion 90a is of the adjusting bolt type, the speed change shaft 80 can be adjusted by inserting a tool from the lower opening side of the saddle type case 13 for adjustment without removing the lid 90.
Overshift can be regulated in a shorter time. Conventionally, an external link, a lever, a motor, etc. are separately provided and used as an overshift restricting member for the speed change shaft 80,
The position adjustment was performed every time the mission case 3 was mounted on the tractor, but this embodiment eliminates the need, and the number of parts is smaller than in the past, which is advantageous in cost.

Further, as shown in FIG. 7, the structure of the transmission mechanism shown in FIG. 4 is modified so that the driving force from the input shaft 4 is applied to the gear 10.
4 through the gear 105 and the counter shaft 4 ', and the transmission shaft 34
Is transmitted to the drive pinion shaft 42 to drive the rear wheels 15, while the rotation of the drive pinion shaft 42 is transmitted via the gears 40 and 106 to the counter shaft 107 and the gear 108. The transmission mechanism may be configured to transmit the driving force to the front wheel drive shaft 75 via either the small diameter gear 72 or the large diameter gear 73 after transmitting the driving force to the gear 67 of the transmission shaft 80.

The input shaft 4, the speed change shaft 34, the drive pinion shaft 42, the speed change shaft 80, the front wheel drive shaft 75, the gear 67, the gear 72, the gear 73, the gear 76, and the gear 77 have been described with reference to FIGS. It has the same function as each shaft and gear group having the same number.

In this structure, the transmission shaft 80 having the key shift 70 is arranged in front of the counter shaft 4 ', and the counter shaft 1
Since the gears 76, 77 and the collar 78 for switching between two-wheel drive, four-wheel drive and front-wheel speed-up drive are arranged in front of 07, in a space smaller than that of the structure of the speed change mechanism shown in FIGS. 4 and 5. A front wheel speed-increasing mechanism can be arranged in the.

Instead of switching between the standard four-wheel drive state and the front wheel speed-up drive state as described above by the mechanical interlocking mechanism interlocking with the operation of the steering wheel 16, the electric motor shown in FIG. And shifter arm 8
It is also possible to have a configuration in which 2 is activated.

As shown in FIG. 8, the operation of the turning angle detection switch 110 provided on the rotating shaft of the steering bundle 16 controls the operation of the electric motor 111 within a predetermined angle range.
Actuating arm 1 that integrally projects from the shifter arm 82
15 is moved via the actuating link 112, which causes the shifter arm 82 to swing back and forth. At this time,
The actuating link 112 and the actuating arm 115 include the coil spring 11
4 has a safety mechanism that is elastically operated. Key shift 70 by swinging the shifter arm 82
Gears 76, 77 for switching between 4WD and speed-up states
Drive the appropriate gear in.

The operating link 112 is a hydraulic circuit 12 for a lifting cylinder 117 (in the cylinder case 9) of a lift arm 10 of a working machine 113 such as a rotary tiller.
Since it is connected to the control valve 121 of 0, the electric motor 111 accelerates the front wheels 14 (rapid turning mode).
Is selected, the lift arm 10 is raised through the control valve 121, and the working machine 113 such as a rotary tiller attached to the rear part of the tractor body is raised.
In a non-working state, the work implement 113 can be prevented from grounding during a sharp turn.

In the structure shown in FIG. 8, the electric motor 111 is operated by the rotating operation of the steering bundle 16.
Actuating arm 1 that integrally projects from the shifter arm 82
Although the shifter arm 82 is moved in the front-rear direction by moving 15 through the operation link 112, in the configuration shown in FIG. 9, the rotation operation of the steering handle 16 causes the electric motor 111 to swing within a predetermined angle range. The operation and motion control is performed, and the operating arm 115 integrally provided so as to project from the shifter arm 82 is moved via the operating link 112, thereby swinging the shifter arm 82 in the front-rear direction. At this time, the operation link 112 and the operation arm 115 are configured to have a safety function of being elastically operated via the coil spring 114. Then, the control valve 121 of the hydraulic circuit 120 for the lifting cylinder 117 of the lift arm 10 is operated and controlled in conjunction with the movement of the operation arm 115.

In this case, the instruction for raising the rotary tiller is slightly delayed as compared with the case shown in FIG. 8 and the headland may be slightly bent, but compared with the case where the handle 16 is operated, the actual Speed increase of tractor (full turn)
The headland is shortened because it can be adjusted in accordance with the movement and tillage is delayed, and if the headland becomes shorter, it is possible to complete the plowing of the headland in one round trip.

FIG. 10 shows an electric motor 111 having the structure shown in FIG.
Instead of this, the cut angle detection switch 110 provided on the handle 16 operates the solenoid valve 123 and the actuator 124, and the solenoid valve 123 connects to the high pressure oil circuit from the main pump of the hydraulic circuit 120 to operate the actuator 124. Then, the actuating arm 115 that integrally projects from the shifter arm 82 is directly moved. This causes the shifter arm 82 to swing back and forth. Further, the operating arm 115 includes a lift arm 10
The control valve 121 for operating the lifting cylinder 117 of FIG.

Also in this case, the speed-up drive of the front wheels 14 and the raising of the rotary tiller can be linked.

As shown in FIG. 1, by disposing the electric motor 111 on the central side of the mission case 3 with respect to the fender 7 and above the lowermost end of the fender 7, mud, water, etc. from the rear wheel 15 can be obtained. I was not affected by the bounce of. Thus, the electric motor assembly has mud resistance and water resistance.

FIG. 11 is a view taken along the line S--S of FIG.
A shift arm position sensor 126 for detecting the movement of the rotary shaft 82a of the shift arm 82 is provided on the shift arm rotary shaft 82a extending from the installation position of the shift arm 82 through the mission case 3 to the opposite side.

By detecting the movement of the rotary shaft 82a of the shift arm 82 by the shift arm position detection sensor 126, the accuracy of the stroke of the shift arm 82 can be further improved.

A potentiometer may be provided as the shift arm position sensor 126. In this case, the movement of the shift arm 82 can be maintained in a designated drive state (two-wheel drive (2WD), four-wheel drive (4WD), or speed-up drive state) and the power supply to the electric motor 111 can be stopped when it is unnecessary. it can.

Conventionally, a control device provided with a proportional valve, a wet clutch, and a controller is known for controlling the operation amount of the shift arm 82, but this control device is very expensive. On the other hand, in the present embodiment, the drive control can be performed inexpensively and reliably.

By using the shift arm position detection sensor 126 such as a potentiometer, it is possible to accurately drive and control one of the two-wheel drive (2WD), the four-wheel drive (4WD), and the speed-up drive state by the operation of the shift arm 82.

[Brief description of drawings]

FIG. 1 is a side view of a tractor according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a circle A portion of FIG.

FIG. 3 is a diagram showing a modified example of FIG.

FIG. 4 is a side sectional view of the tractor of FIG. 1 inside a mission case.

5 is an enlarged side sectional view of a double-speed case that is a main part attached to the front end of the transmission case of the tractor of FIG.

FIG. 6 is an enlarged side sectional view of the transmission unit in FIG.

7 is an enlarged side cross-sectional view of a main part of a modified example in the mission case of the tractor of FIG.

FIG. 8 is a configuration diagram of a drive state switching unit of the tractor according to the embodiment of the present invention.

FIG. 9 is a configuration diagram of a drive state switching unit of the tractor according to the embodiment of the present invention.

FIG. 10 is a configuration diagram of a drive state switching unit of the tractor according to the embodiment of the present invention.

FIG. 11 is a view taken along the line SS of FIG.

[Explanation of symbols]

1 tractor 2 engine 3 transmission case 4 input shaft 4'counter shaft 5 main transmission device 6 auxiliary transmission device 7 fender 8 double speed case 9 hydraulic cylinder case 10 lift arm 11 lower link 12 lift rod 13 saddle type case 14 front wheel 15 rear wheel 16 Steering handle 17 Connection shaft 18 Main clutch case 34 Shift shaft 35 Gear 37 Needle bearing 38, 39 Main shift gear 40 Sub shift gear 41 Pinion gear 42 Pinion drive shaft 43 Side gear 44 Two-step gear 45 Cylindrical shaft 47, 48 Gear 49 Back idle shaft 50 Back Gear 51, 52 Operation Lever 55 PTO Drive Shaft 55a Protrusion 56 Two-step Gear 57 Large Diameter Gear 58, 59 Clutch Claw 60, 61 Gear 63 PTO Shaft 64 Two-step Gear 65 Power Extraction Gear 66 Bearing 67 Large-diameter gear 67a Cylindrical part 70 Key shift claw 71 Groove 72, 73 Gear 72a 73a Locking groove 75 Front wheel drive shaft 76, 77 Gear 78, 79 Collar 78a Locking groove 80 Speed change shaft 80a Protrusion 82 Shifter arm 82a Rotating shaft 83 Engagement Stop pin 84 Concave 86 Horizontal shaft 87 Pin 88 Spring 89 Boss 90 Lid 90a Protrusion 91 Bolts 104, 105 Gear 106 Gear 107 Counter shaft 108 Gear 110 Break angle detection switch 111 Electric motor 112 Working link 113 Working machine 114 Coil 115 Acceleration Operation arm 117 Lifting cylinder 120 Hydraulic circuit 121 Control valve 123 Solenoid valve 124 Actuator 126 Position detection sensor

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Claims (3)

[Claims] 1. A standard four-wheel drive state of front and rear wheel drive in which the rotational peripheral speed of the front wheels 14 becomes substantially the same as the rotational peripheral speed of the rear wheels 15 from the drive source 2 via the transmission system in the mission case 3. A power vehicle having a transmission capable of switching to a front-wheel speed-up state in which the rotational peripheral speed of the front wheels 14 is higher than the rotational peripheral speed of the rear wheels 15 in accordance with the turning motion of the vehicle body. , A speed change shaft 8 that moves in the axial direction by a predetermined distance
0 and a stepped transmission mechanism (gear 7
2, 73, 76, 77) and an engaging mechanism (key shift claw 70, locking grooves 72a, 7) that expands and contracts when the speed change shaft 80 moves.
3a, etc.), and further, at one end side or the other end side of the speed change shaft 80, the speed change shaft 8
A transmission for a power vehicle, comprising: a regulating member that regulates a movement of 0 or more over a predetermined interval. 2. The transmission of a power vehicle according to claim 1, wherein the restricting member is configured to be adjustable from the outside of the machine body. 3. A standard four-wheel drive state of front and rear wheel drive in which the rotational peripheral speed of the front wheels 14 becomes substantially the same as the rotational peripheral speed of the rear wheels 15 from the drive source 2 via the transmission system in the mission case 3. A power vehicle having a transmission capable of switching to a front wheel speed increasing state in which the rotational peripheral speed of the front wheels 14 is higher than the rotational peripheral speed of the rear wheels 15 in accordance with a turning operation of a steering wheel 16 of a vehicle body, A power vehicle has a work machine 113 at the rear part thereof and the work machine 113.
The transmission is provided with a hydraulic control circuit 120 for raising and lowering the gear, and the transmission includes a transmission shaft 80 that moves a predetermined distance in the axial direction and a stepped transmission mechanism (gear 72,
73, 76, 77) and an engaging mechanism (key shift claw 70, locking grooves 72a, 73a) that expands and contracts when the speed change shaft 80 moves.
Further, an actuator (electric motor 111, actuator 124) that operates in conjunction with the turning operation of the steering handle 16 is provided.
0 is interlockingly connected via a connecting tool, and is provided with a control means for raising the rear work implement 113 when the speed change position of the speed change shaft 80 selects the front wheel speed increasing state. .