JP4219310B2 - Transmission - Google Patents

Description

  The present invention relates to a chain-type transmission in which a shift is performed by changing a chain between a plurality of transmission sprockets, and the transmission is provided, for example, in a bicycle.

As this type of transmission, for example, a bicycle transmission disclosed in Patent Document 1 is coupled to a drive sprocket that is drivingly connected to a crankshaft via a one-way clutch and an output shaft that drives a rear wheel. A sprocket group including a plurality of transmission sprockets, a drive sprocket, a chain wound around the transmission sprocket, and a transmission switching mechanism are provided. The speed change mechanism includes a derailleur arm that rotatably supports a guide pulley that guides the chain to a selected speed change sprocket, and an arm that rotatably supports a tension pulley that applies tension to the chain. As the pulley moves in the direction of the center axis of the derailleur shaft, the chain is replaced in the sprocket group, and the speed is changed.
JP 2004-155280 A

  By the way, it is possible to perform a gear shifting operation when the driver gets off the bicycle in reverse or when the bicycle is stopped, and the desired gear shifting is performed promptly by the forward rotation of the crankshaft. Since the speed change operation is possible even in the state, it contributes to the improvement of the driving performance of the bicycle. In particular, in bicycle races that compete for time, increasing the opportunities for gear shifting operations improves race performance.

  However, when the speed change sprocket is stopped, such as when the bicycle is stopped, and the guide pulley and tension pulley move in the direction of the central axis (hereinafter referred to as “axial direction”), the chain of the tension pulley On the winding side, the chain winding part moves in the axial direction together with the tension pulley, whereas the chain winding part in the drive sprocket hardly moves in the axial direction, and the chain is in a stopped state. Therefore, the chain may come off from the tension pulley on the winding side of the tension pulley. When the crankshaft is rotated forward in this state and the drive sprocket and the transmission sprocket rotate forward, the disengagement part, which is the part of the chain that has been removed, is caught between the tension pulley and the arm, or the tension pulley It becomes difficult for the disengagement part to re-engage with the tension pulley, for example, by being positioned radially inward from the outermost peripheral end of the tension pulley.

The present invention has been made in view of such circumstances, and the inventions according to claims 1 to 4 are such that, even when the chain is detached from the tension pulley by a speed change operation, the detached chain is engaged with the tension pulley. It is easy to return to the combined state , and to provide a transmission that can perform a speed change operation even in a rotation state in which the speed change sprocket is not rotating forward, including a case where the speed change sprocket is stopped , and a speed change operation. The purpose is to make it easier . The invention described in claim 2 further aims to increase the rigidity of the arm and improve the certainty of returning the disengaged portion to the engagement state with the tension pulley. further improves the reliability of the return of the engagement of the tension pulley of the withdrawal unit, the purpose of reducing the weight of the arm.

The invention according to claim 1 includes a plurality of transmission sprockets arranged in the axial direction, and a switching mechanism that switches a chain between the plurality of transmission sprockets according to a shifting operation. An arm that rotatably supports a tension pulley that applies tension to the chain, and the arm moves in an axial direction by a speed change operation. In the arm, the chain is wound around the tension pulley. An engagement return guide portion that engages the tension pulley with a detachment portion of the chain that is off the raceway surface of the tension pulley is provided on the side, and the engagement return guide portion includes the entire release portion as the tension pulley. The outer circumferential end of the raceway is positioned radially outward from the rotation locus of the outermost end, and the detachment portion is caused by the tension of the chain. Said guides so as to tension pulley engaging After moving toward, the arm comprises an arm portion of a pair disposed on both sides of the tension pulley in the axial direction, said each arm portion, said An engagement return guide portion is provided, and each engagement return guide portion has a guide surface that extends in the axial direction in a direction away from the raceway surface while contacting with the disengagement portion, and the guide surface is the most in the axial direction. The end near the tension pulley is a transmission that is at substantially the same position as the inner periphery of the chain engaged with the tension pulley .

According to this, even when the chain is detached from the raceway surface due to the movement of the tension pulley in the axial direction due to the speed change operation, such as when the speed change sprocket is stopped, the engagement return guide part causes the chain to be detached. The part is guided by the engagement return guide part and returned to the engaged state with the tension pulley, so that the disengaged part is prevented from being caught between the tension pulley and the arm, and the chain travels. It becomes possible.
In addition, since the disengagement part easily rides on the guide surface, the start part of the disengagement part is located closer to the positive rotation direction of the tension pulley in the engagement return guide part. The degree of twisting is alleviated and the resistance force from the chain during the shifting operation is reduced.

According to a second aspect of the present invention, in the transmission according to the first aspect, the switching mechanism includes a guide pulley that guides the chain wound around one operating sprocket selected from the plurality of transmission sprockets. the with the guide pulley rotatably supports a movable holder in the axial direction together with the arm, the two arm portions are arranged on both sides of the tension pulley and the guide pulley in the axial direction, the Each arm part is formed with a tension pulley side guide part for preventing the chain pulley from coming off in the tension pulley, and a supported part supported by the holder, and a shaft between the supported parts. The interval in the direction is larger than the interval in the axial direction between the tension pulley side guide portions.

  According to this, it is possible to increase the bending rigidity in the supported portion, which is a portion where the force for moving the arm in the axial direction acts from the switching mechanism. Also, by reducing the axial distance between the tension pulley side guide portions in the arm, the tension pulley side guide portion can be disposed close to the tension pulley, so that the release guided by the engagement return guide portion. The part can be reliably returned to the engaged state with the tension pulley.

According to a third aspect of the present invention, in the transmission according to the second aspect, the formation range in the circumferential direction of each engagement return guide portion includes a rotation center line of the tension pulley and a rotation center line of the guide pulley. This is a range in which substantially the same angle is formed in the forward rotation direction and the reverse rotation direction of the tension pulley around the rotation center line of the tension pulley in a side view with respect to the center plane.

  According to this, since the formation range in the circumferential direction of the engagement return guide portion can be sufficiently secured around the center plane, the release portion can be easily returned to the engagement state with the tension pulley. In addition, since the point of action of the force that acts on the engagement return guide portion by the disengagement portion that contacts the engagement return guide portion can be close to the center plane, the torque acting on each arm portion by the force can be reduced. Therefore, in order to increase the torsional rigidity of each arm part, it is not necessary to enlarge each arm part and increase its weight.

According to a fourth aspect of the present invention, in the transmission according to any one of the first to third aspects , the width in the axial direction of each engagement return guide portion is substantially equal to the width of the chain. The arm portion has a disengagement preventing portion that is provided closer to the positive rotation direction side of the tension pulley than the engagement return guide portion to prevent the chain from coming off from the tension pulley, and each disengagement preventing portion includes: The disengagement prevention portions of the both arm portions extend radially outward from the engagement return guide portion, and the connecting portions are radially outward from the chain winding portion of the tension pulley. The engagement return guide portions are configured such that the distance between the engagement return guide portions in the axial direction gradually decreases toward the both come-off prevention portions in the positive rotation direction of the tension pulley. , Taper guide It is intended to.

According to invention of Claim 1, the following effect is show | played. That is, when the speed change sprocket is stopped, the disengagement part that is disengaged from the raceway surface of the tension pulley by the speed change operation is guided by the engagement return guide part and is reengaged with the tension pulley so that the chain can travel. It becomes easy for the disengagement part to return to the engagement state with the tension pulley, and the speed change operation is possible even in the rotation state where the speed change sprocket is not rotating forward, including the stop state of the speed change sprocket. Shifting can be executed.
Further, during the speed change operation, the resistance force from the chain due to the twisting of the chain is reduced, so that the speed change operation is facilitated.

  According to invention of Claim 2, in addition to the effect of the invention of the cited claim, there exists the following effect. That is, since the rigidity of the supported portion to which the force from the changing mechanism for moving the arm in the axial direction acts is increased, the weight can be reduced. Moreover, since the detachable portion can be reliably returned to the engaged state with the tension pulley, the reliability of the detachable portion to be returned to the engaged state is improved.

  According to invention of Claim 3, in addition to the effect of the invention of the cited claim, there exist the following effects. That is, since the formation range in the circumferential direction of the engagement return guide portion can be sufficiently ensured, the reliability of the return portion to the engagement state with the tension pulley is improved. Moreover, since the torque which acts on each arm part by the force which a detachment part acts on an engagement return guide part can be reduced, weight reduction of each arm part is attained.

According to invention of Claim 4, in addition to the effect of the invention of the cited claim, there exists the following effect. That is, the detachment preventing portion prevents the detachment of the chain from the tension pulley .

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
Referring to FIG. 1, a bicycle B having a transmission T to which the present invention is applied includes a vehicle body frame F, a pedal-type crankshaft 12, a transmission T, and an output shaft 15 that is rotationally driven by the power after the shift. And a transmission device including a driving force transmission mechanism.

  The vehicle body frame F includes a head pipe 1 that pivotally supports a front fork 6 having a lower end portion that supports a front wheel Wf and a handle 7 attached to the upper end portion, and a pair of left and right sides that extend rearward and obliquely downward from the head pipe 1. Main frame 2, a down tube 3 extending obliquely downward and rearward from the front end portions of both main frames 2, and a pair of left and right undertubes connecting the rear end portions of both main frames 2 and the rear end portions of down tubes 3. 4 and a saddle frame 5 that extends from each main frame 2 and supports the saddle 8. Both the main frame 2 and the down tube 3 are members formed separately and joined by welding.

  In the specification or claims, the top, bottom, front, back, left, and right coincide with the top, bottom, front, back, left, and right of the bicycle B, respectively. Further, the axial direction means the direction of the rotation center line L3 of the transmission sprockets 41 to 47, and the side view means viewing from the axial direction.

  A pivot shaft 9 (see also FIG. 3) provided at the rear portion 2a of both main frames 2 has a front end of a pair of left and right swing arms 10 that support a rear wheel Wr via an axle attached to the rear end portion. The part is supported to be swingable. Both the swing arms 10 are connected to both the main frames 2 via the rear suspension 11, and can swing up and down around the pivot shaft 9 together with the rear wheel Wr.

  A transmission T and a crankshaft 12 rotatably supported by the transmission T in a space formed between the rear portions 2a of the main frames 2 and the undertubes 4 at the lower part of the body frame F A main shaft 12a and an output shaft 15 are arranged. The driving force transmission mechanism is arranged on the right side of the vehicle body frame F. Here, when one side of the bicycle B in the vehicle width direction (corresponding to the left-right direction) or the axial direction is the left side, the right side is the other side in the vehicle width direction or the axial direction.

  Referring also to FIG. 2, the transmission T includes a pair of left and right first and second case parts 21, which are coupled by bolts B <b> 1 (see FIG. 5) at two bosses 21 a and 22 a formed on the peripheral edge part. A metal case 20 composed of 22 is provided. The case 20 has a pair of mounting portions (the mounting portion 21b of the first case portion 21 shown in FIG. 2) formed on the peripheral edge portions of the case portions 21 and 22 by bolts B2. It is fixed to both main frames 2 and both undertubes 4, respectively. The first and second case portions 21 and 22 formed of a plate material are formed by cutting, casting or pressing.

  Referring also to FIG. 3, the crankshaft 12 is coupled to the main shaft 12 a disposed through the lower portion of the case 20 in the left-right direction and the left and right ends of the main shaft 12 a protruding to the outside of the case 20. And a pair of crank arms 12b. The crankshaft 12 is rotatably supported by the first and second case portions 21 and 22 via a pair of bearings 14. A pedal 13 (see FIG. 1) is rotatably attached to each crank arm 12b.

  The output shaft 15 is obliquely above and forward of the main shaft 12a, the pivot shaft 9 is almost directly above the main shaft 12a, the rotation center line L2 of the output shaft 15 and the swing center line of the swing arm 10 are parallel to each other, and It is arranged so as to be parallel to the rotation center line L1 of the crankshaft 12 and within the rotation locus of the crank arm 12b. The pivot shaft 9 fixed to the main frame 2 is inserted into through holes of bosses 21c and 22c formed in the first and second case portions 21 and 22, and supports the first and second case portions 21 and 22. .

  Referring to FIG. 4, the output shaft 15 accommodated in the case 20 has an end portion 15a protruding rightward from the second case portion 22, and the output drive as an output drive rotator on the end portion 15a. Sprocket 17 is coupled. Referring also to FIG. 1, an output chain 19 as a flexible output endless transmission band is connected to a drive sprocket 17 and an output driven sprocket 18 as an output driven rotating body drivingly connected to the rear wheel Wr. Is passed. The driving sprocket 17, the chain 19, and the driven sprocket 18 constitute the driving force transmission mechanism that drives the rear wheel Wr as a driving wheel.

Hereinafter, the transmission device T will be further described.
2 to 4, the transmission T includes a case 20, a chain-type transmission mechanism M1, and a transmission switching mechanism M2 that switches the transmission mechanism M1 to a desired transmission position according to a transmission operation. A later-described derailleur 70, which is a component of the speed change mechanism M1 and the speed change switching mechanism M2, is accommodated in the case 20.

  The speed change mechanism M1 includes a one-way clutch 30, a ball spline 31 as a slide mechanism, a drive sprocket 32, a plurality of speed change sprockets 41 to 47 as driven sprockets, an endless speed change chain C, and a chain guide member 50.

  A drive sprocket 32 as a common sprocket is coaxially arranged on a main shaft 12a of a crankshaft 12 as an input shaft that is rotationally driven by a driver and receives drive torque. The drive sprocket 32 is drivingly connected to the main shaft 12a via the one-way clutch 30. The one-way clutch 30 is disposed between a clutch inner 30a formed of a part of the main shaft 12a, a clutch outer 30b with ratchet teeth formed on the inner periphery, and the clutch inner 30a and the clutch outer 30b. And a clutch element 30c composed of mating claws, and the forward rotation direction A0 of the crankshaft 12 (hereinafter, the forward rotation direction of various shafts and sprockets when the crankshaft 12 rotates in the forward rotation direction A0 is denoted by reference numeral A0. )) Is transmitted to the drive sprocket 32 only.

  Between the one-way clutch 30 and the drive sprocket 32, the drive sprocket 32 can be moved in the direction A1 (also in the axial direction) of the rotation center line L1 with respect to the main shaft 12a and the clutch of the one-way clutch 30. A ball spline 31 that rotates integrally with the outer 30b is provided. The ball spline 31 is integrally coupled to the clutch outer 30b by a connecting pin 33 and is supported rotatably on the outer periphery of the main shaft 12a via a bearing 34, and radially inward of the inner cylinder 31a. Arranged coaxially with the cylinder 31a and coupled integrally with the drive sprocket 32, and arranged between the inner cylinder 31a and the outer cylinder 31b, the rotation center line L1 is provided between the inner cylinder 31a and the outer cylinder 31b. And a plurality of balls 31c that are accommodated so as to roll over a pair of accommodation grooves formed extending in parallel with the grooves. The pair of receiving grooves is provided in a plurality of sets, in this embodiment, three sets. Therefore, the outer cylinder 31b and the drive sprocket 32 rotate integrally with the inner cylinder 31a via the ball 31c, while the rotation center line direction with respect to the main cylinder 12a and the inner cylinder 31 immovable in the rotation center line direction A1. It is possible to move to A1.

  The output shaft 15 rotatably supported by the case 20 via a pair of bearings 35 respectively held by the case portions 21 and 22 has a plurality of different outer diameters (that is, the tip diameter) and the number of teeth. In this embodiment, the sprocket group 40 composed of seven transmission sprockets 41 to 47 is coupled by splines so as to rotate integrally with the output shaft 15 and to be coaxial with the output shaft 15. Therefore, the rotation center line L3 of each of the transmission sprockets 41 to 47 coincides with the rotation center line L2 of the output shaft 15 parallel to the rotation center line L1 of the crankshaft 12. All of the transmission sprockets 41 to 47 are arranged side by side in the axial direction in order from the lowest speed 1st speed transmission sprocket 41 to the highest speed 7th speed transmission sprocket 47. Then, the seven transmission sprockets 41 to 47 are arranged so as to have a large diameter sequentially toward the left.

  An operating sprocket (hereinafter simply referred to as “operating sprocket”) which is one of the transmission sprockets 41 to 47 selected by the transmission switching mechanism M2 from the drive sprocket 32 and the sprocket group 40. In FIG. Or the state where the transmission sprocket 47 is an operating sprocket is illustrated). Therefore, the output shaft 15 is rotationally driven by the crankshaft 12 at a gear ratio determined by the driving sprocket 32 and the operating sprocket that is drivingly connected via the chain C.

  2 and 5, the chain guide member 50 is disposed between the drive sprocket 32 and the sprocket group 40, and is disposed on the tight side of the chain C driven by the crankshaft 12 rotating in the forward direction. Chain bending prevention means is configured to prevent the bent chain C from being caught between the drive sprocket 32 and the case 20 when bending due to a decrease in tension occurs on the tension side.

  The chain guide member 50 includes a guide portion 51 that forms an opening 52 having an axial width slightly larger than the axial width of the sprocket group 40, and a chain C that is unwound from each of the transmission sprockets 41 to 47. And a regulating unit 53 that regulates movement to the inside of the track. A guide 51 for guiding the chain C entering the opening 52 from each of the speed change sprockets 41 to 47 includes an inner guide 51a disposed closer to the inside of the chain track with respect to the opening 52, and a chain track with respect to the opening 52. The outer side guide part 51b arrange | positioned at the outer side is comprised from the side part guide parts 51c and 51d each arrange | positioned with respect to the opening 52 at the both sides in an axial direction. The outer guide 51b has a first portion 51b1 that forms an opening 52 in cooperation with the inner guide 51a and the side guides 51c and 51d, and an opening located closer to the sprocket group 40 than the first portion 51b1. 52 includes a roller 51b2 as a second portion for guiding the chain C to 52. Further, the restricting portion 53 arranged at a position overlapping the respective transmission sprockets 41 to 47 in a side view extends from the inner guide portion 51a toward the respective transmission sprockets 41 to 47, and the teeth of the respective transmission sprockets 41 to 47 are provided. The individually passing grooves 53b have tip portions 53a formed in the same number as the transmission sprockets 41 to 47.

  The inner guide portion 51a, the first portion 51b1, the restricting portion 53, and the left side guide portion 51c are configured by a single first member made of synthetic resin, and the right side guide portion 51d is a first portion made of synthetic resin. It is composed of two members. The first and second members are coupled to the first case portion 21 by a pair of bolts B3, whereby the chain guide member 50 is fixed to the case 20. On the other hand, the roller 51b2 is rotatable on the support shaft 54 supported at both ends thereof on the left side guide portion 51c and the first case portion 21 and on the right side on the side guide portion 51d and the second case portion 22, respectively. Supported.

  Therefore, for example, when the bicycle B moves up and down violently within a short time due to road undulations, vibration on the chain C on the tension side of the chain C or on the inside and outside of the chain track When the chain C passes through the opening 52, the vibration is generated and the amplitude of the chain C comes into contact with the inner guide part 51a and the outer guide part 51b. Smooth running is possible.

  Further, when the chain C travels such that the tension of the chain C is deflected due to a decrease in tension, for example, when the bicycle B moves forward with the crankshaft 12 stopped or reversely rotated, the drive sprocket 32 is The wheel is driven to rotate in the forward rotation direction A0 through the chain C by the torque transmitted from the wheel Wr to the sprocket group 40 through the driving force transmission mechanism and the output shaft 15. At this time, the tension on the tension side decreases, and the tension side may bend, particularly when the bicycle B travels forward in a state where the crankshaft 12 that has been normally rotated suddenly stops or reversely rotates. In some cases, the chain C is significantly bent and folded in front of the drive sprocket 32, and the folded portion may be caught between the drive sprocket 32 and the case 20.

  However, even if a bent portion is generated on the tension side by providing the chain guide member 50, when the chain C passes through the opening 52, the chain C comes into contact with the inner guide portion 51a or the outer guide portion 51b and the amount of the bent portion. Is restricted, the bending of the chain C is reduced.

  Further, when the tension side is significantly bent, the bent portion is restricted by the restriction portion 53 of the chain guide member 50, and is prevented from being caught in the transmission sprockets 41 to 47, and the restriction portion 53 Along the guide 51 and temporarily stays between the guide 51 and the sprocket group 40 closer to the sprocket group 40 than the drive sprocket 32 and the opening 52 (FIG. 6 shows a chain C2). One form when C stays is shown. In this way, the chain guide member 50 prevents the bent portion of the chain C formed on the tension side from being caught between the drive sprocket 32 and the case 20. The guide surface of the inner guide portion 51a and the roller 51b1 guide the chain C so that the stay portion C2 passes through the opening 52 in a state where the stay portions C2 are aligned in a straight line. It is also a chain aligning means for aligning.

  Further, when the speed change position obtained by the sprocket group 40 is divided into a low speed side position and a high speed side position, on the tight side of the chain C, the inner guide portion 51a is a speed change sprocket 44˜ which is an operating sprocket at the high speed side position. The roller 51b1 comes into contact with the chain C wound around the speed change sprockets 41 to 43, which are operating sprockets at the low speed side position.

  2, 4, and 6 to 9, both end sprockets located at the end in the axial direction in the sprocket group 40 and both adjacent sprockets adjacent to the case 20 in the axial direction. Of the transmission sprockets 41 and 47, the transmission sprocket 41 closer to the case 20 in the axial direction exceeds the transmission sprocket 41 when the chain C is switched to the transmission sprocket 41 by the derailleur 70 moving in the axial direction. Thus, the transmission device T is provided with a protruding portion 56 as a restricting portion that prevents the chain C from moving in the axial direction using the case 20.

  Specifically, the first case portion 21, which is a part of the case 20, has a chain C in the sprocket group 40 at a position overlapping the winding portion C 1 of the chain C in the transmission sprocket 41 in a side view. A projecting portion 56 that continuously restricts the movement of the chain C in the axial direction in the direction approaching the first case portion 21 beyond the speed change sprocket 41 during the changeover is provided continuously. The protrusion 56 has a top surface 56d as a restricting surface for restricting movement in the axial direction on the top 56c in the axial direction. When the chain C attempts to move in the axial direction beyond the transmission sprocket 41, the chain C is prevented from coming off the transmission sprocket 41 by contacting the top surface 56d.

  The protrusion 56 has a first portion 56a that overlaps the winding portion C1 in a side view, a second portion 56a that is continuous with the first portion 56a and extends in the forward rotation direction A0 more than the first portion 56a on the unwinding side of the transmission sprocket 41. A portion 56b. The second portion 56b extends from the first portion 56a toward the restricting portion 53 of the chain guide member 50. When the crankshaft 12 is not rotating forward, the second portion 56b is retained in the chain C by the chain guide member 50. When the guide pulley 72 moves in the axial direction toward the speed change sprocket 41 by the speed change operation in a state where the gear is formed, the staying portion C2 exceeds the speed change sprocket 41 and approaches the first case portion 21 in the axial direction. To prevent.

  Further, the first case portion 21 is provided with a reinforcing rib extending from the protruding portion 56 in the radial direction of the transmission sprocket 41 by integral molding. The reinforcing ribs include a plurality of inner ribs 57 extending radially outward from the projecting portion 56 and spaced apart in the circumferential direction, and a plurality of outer ribs spaced from the projecting portion 56 in the circumferential direction. 58. The inner rib 57 is provided so as to protrude in the axial direction in the same direction as the protruding portion 56, and the top surface 57a in the axial direction of the inner rib 57 is substantially at the same position as the top surface 56d. Further, the same number of outer ribs 58 as the inner ribs 57 are provided at the same angular positions as the inner ribs 57 around the rotation center line L3 in a side view.

  Referring to FIGS. 1 to 3, the shift switching mechanism M <b> 2 includes a shift operation mechanism 60, a derailleur 70 as a switching mechanism that switches the chain C in the sprocket group 40 in accordance with a shift operation by the shift operation mechanism 60. Is provided. The chain C is stretched over a drive sprocket 32, an operating sprocket, and a guide pulley 72 and a tension pulley 82 that are all arranged on the slack side of the chain C driven by the crankshaft 12 that rotates forward.

  A speed change operation mechanism 60 connected to the derailleur 70 in the case 20 includes a speed change operation member 61 composed of a speed change lever operated by the driver, and a speed change operation for transmitting the operation of the speed change operation member 61 to the derailleur 70. An operation cable 62 is provided as an operation force transmission member for operatively connecting the operation member 61 and the derailleur 70. The operation cable 62 includes a tubular outer cable 62a held by the vehicle body frame F, and an inner cable 62b inserted inside the outer cable 62a. The inner cable 62b is coupled to the speed change operation member 61 at one end and is coupled to the derailleur 70 at the other end.

  2 to 5 and 9, the derailleur 70 disposed above the main shaft 12a of the crankshaft 12 is fixed and held by the case portions 21 and 22, and the holding portion 71a of the outer cable 62a is held by the derailleur 70a. A cylindrical base 71 provided, a guide pulley 72 as a guide member for guiding the chain C so as to be wound around the operating sprocket when the chain C is exchanged between the transmission sprockets 41 to 47, and a guide pulley 72 The holder H that is rotatably supported, the base 71, and the holder H are connected, and the holder H and the guide pulley 72 are moved in the axial direction and the radial direction of the rotation center line L3 according to the speed change operation by the speed change operation mechanism 60. A parallel link mechanism 73 having a pair of links 73a and 73b as an operation mechanism and a tensioner 74 for applying tension of the chain C are provided.

  The holders H are arranged on the left and right sides on both sides in the axial direction with respect to the guide pulley 72 having a rotation center line L4 parallel to the rotation center line L3, and are connected by a pair of rivets 75a and 75b. The first and second holder portions 76 and 77 and a support portion 78 that rotatably supports the guide pulley 72 are configured. The support portion 78 is fitted on a rivet 75a as a connecting portion between the first and second holder portions 76 and 77, and a collar 78a defining the interval in the axial direction of the first and second holder portions 76 and 77; The bearing 78b is externally fitted to the collar 78a and supports the guide pulley 72. An inner portion 78b1 of a bearing 78b that is swingably supported by the collar 78a defines an axial interval between a pair of first and second arm portions 100 and 120, which will be described later, and both arm portions coupled by press-fitting. Swings together with 100 and 120.

  The first holder portion 76 is disposed on the left side with respect to the guide pulley 72 and is configured by a plate-like member. The second holder part 77 is arranged on the outer side in the radial direction of the guide pulley 72, and is arranged on the right side with respect to the guide pulley 72, and a connecting part 79 to which a pair of links 73a, 73b are pivotally connected. And a spring accommodating portion 80 for accommodating the tension spring 83. The both links 73a and 73b of the parallel link mechanism 73 are pivotally attached to the base 71 via a pair of support shafts 81 provided on the base 71, and are locked to the connecting portion 73b1 of one link 73b. When operated by 62b, it swings around a pair of swing centerlines defined by each support shaft 81, and along the tip circles composed of the tip circles of the respective transmission sprockets 41-47. Guide pulley 72 is guided.

  Referring also to FIG. 11, the spring accommodating portion 80 constitutes a second extending portion disposed on the right side of the track surface P1 of the guide pulley 72 in the axial direction with respect to the first extending portion 106 described later. A peripheral wall 80a. Specifically, a spring accommodating portion 80 provided at a position adjacent to the second arm portion 120 described later in the axial direction is located on the right side of the second arm portion 120 and on the right side of the raceway surface P1 from the raceway surface P1. The peripheral wall 80a extends parallel to the axial direction in a direction away from the peripheral wall 80a, and the peripheral wall 80a has a portion of the outer peripheral surface formed of a cylindrical surface as a guide surface 80b. The axial distance between the second arm portion 120 and the spring accommodating portion 80 is much smaller than the width W4 in the axial direction of the chain C, and the detaching portion C13 is a guide surface of the peripheral wall 80 as will be described later. It is set to such an extent that it does not hinder movement when sliding on 80b and returning to the engaged state with the guide pulley 72.

Here, the raceway surface P1 of the guide pulley 72 intersects a large number of teeth 72a (see FIGS. 9 and 10) which are engaging portions with the chain C in the guide pulley 72 and is a plane orthogonal to the rotation center line L4. It is. (FIG. 11 shows one of the raceways intersecting with the teeth 72a.)
2 and 4, the tensioner 74 includes a tension pulley 82 that presses the chain C between the drive sprocket 32 and the guide pulley 72 to apply tension to the chain C, and first and second axially. An arm R that is disposed between the holder portions 76 and 77 and is integrally coupled to the support portion 78 of the holder H by press-fitting and rotatably supports the tension pulley 82, and a tension spring 83 are provided. The holder H and the arm R constitute a holder member in the derailleur 70.

  The arms R are respectively disposed on the left and right sides that are both sides of the tension pulley 82 in the axial direction and are paired with the first first and second holder portions 76 and 77 in the axial direction. , Second arm portions 100 and 120, and a support portion 84 that rotatably supports the tension pulley 82.

  The first and second arm portions 100 and 120 prevent the chain C from being detached from the guide pulley 72 and support guide pulley side guide portions 101 and 121 as supported portions supported by the support portion 78, respectively. Tension pulley side guide portions 102 and 122 that support the portion 84 and prevent the chain C from being detached from the tension pulley 82. The support portion 84 includes a rivet 84a as a connecting portion between the first and second arm portions 100 and 120, and a bearing 84b that is externally fitted to the rivet 84a and supports the tension pulley 82.

  The axial distance W1 between the two guide pulley side guide portions 101, 121 defined by the inner 78b1 of the bearing 78b is the same as that of the two tension pulley side guide portions 102, 122 defined by the inner 84b1 of the bearing 84b. It is set larger than the interval W2 in the axial direction. Further, the width of the guide pulley 72 in the axial direction is larger than the width of the tension pulley 82 in the axial direction.

  The tension spring 83 is composed of springs 83a and 83b composed of two torsion coil springs having different diameters, and both springs 83a and 83b are disposed concentrically in the spring accommodating portion 80. Each spring 83a, 83b has one end locked to the spring accommodating portion 80, and the other end locked to the locking portions 120a, 120b (see FIG. 10) of the second arm portion 120. Thus, the arm R and the tension pulley 82 are urged clockwise in FIG. 2 around the rotation center line L4, and the tension pulley 82 is pressed against the chain C. Then, the tension pulley 82 swings together with the arm R, so that the tension of the chain C is adjusted according to the elastic force of each spring 83a, 83b.

  Referring to FIGS. 9 and 10, the first arm portion 100 includes a fan-shaped guide pulley side guide portion 101 formed in a circumferential range including the winding portion C3 of the chain C in the guide pulley 72, and a tension pulley 82. A plate-shaped member in which a fan-shaped tension pulley side guide portion 102 formed in a circumferential range including the winding portion C4 of the chain C and a connecting portion 103 for connecting both guide portions 101 and 102 are integrally formed. It is.

  The guide pulley-side guide portion 101 is connected to the large-diameter outer peripheral edge portion 104 provided on the guide pulley 72 on the winding side of the chain C, and is connected to the large-diameter outer peripheral edge portion 104, and also the unwinding side of the chain C in the guide pulley 72 And a small-diameter outer peripheral edge portion 105 provided on the outer periphery. The large-diameter outer peripheral edge portion 104 is in a position overlapping the winding portion C3 in a side view, and the small-diameter outer peripheral edge portion 105 is more inward in the radial direction than the large-diameter outer peripheral edge portion 104 and the winding portion C3. , Located near the rotation center line L4. The small-diameter outer peripheral edge portion 105 has an end portion 105a in the circumferential direction at a position intersecting with a center plane P3 described later. Further, the connecting portion 103 constitutes a detachment preventing portion that prevents the chain C from coming off the guide pulley 72 to the left on the winding side of the chain C at the guide pulley 72.

  Referring also to FIG. 11, both outer peripheral edge portions 104, 105 have first extending portions extending parallel to the axial direction in the direction away from the raceway surface P1 to the left of the raceway surface P1 of the guide pulley 72 in the axial direction. 106 is provided. The extending portion 106 disposed on the left side of the raceway surface P1 of the guide pulley 72 in the axial direction extends continuously over both outer peripheral edge portions 104 and 105, and the chain C is wound around the guide pulley 72. On the insertion side, it extends continuously to the edge 103a of the connecting portion 103 to a position overlapping the tension pulley 82 in the axial direction. The extending portion 106 is formed in an arc shape at both outer peripheral edge portions 104 and 105, and is formed in a straight shape at the edge portion 103a of the connecting portion 103. The extending portion 106 is formed by bending the guide pulley side guide portion 101 and the connecting portion 103 substantially parallel to the axial direction, and is formed on the guide pulley side guide portion 101 and the connecting portion 103, and thus on the first arm portion 100. It is integrally molded.

  The guide surface 107 constituted by the outer peripheral surface of the extending portion 106 extends substantially parallel to the axial direction in a direction away from the track surface P1, in this case, to the left, and guides at both outer peripheral edge portions 104 and 105. Smoothly continues to the surfaces 104b and 105b facing the pulley 72. Further, the width W3 of the extending portion 106 or the guide surface 107 in the axial direction is equal to the width W4 in the axial direction of the chain C and the axial direction occupied by the two transmission sprockets 41 to 47 adjacent in the axial direction of the sprocket group 40. Is substantially equal to the width W5 (in FIG. 9, the width occupied by the two transmission sprockets 45 and 46 is representatively shown). The width W6 of the peripheral wall 80a or the guide surface 80b of the spring accommodating portion 80 in the axial direction is set to be larger than the width W3 of the extension portion 106 or the guide surface 107.

  Further, the extended portion 106 and the guide surface 107 at the small-diameter outer peripheral edge portion 105 are formed by the extended portion 106, the guide surface 107 and the guide pulley at the large-diameter outer peripheral edge portion 104 at a position overlapping the winding portion C3 in a side view. It is located closer to the rotation center line L4 than the rotation locus 72c at the outermost peripheral end of 72. Then, as the small-diameter outer peripheral edge portion 105 approaches the end portion 105a from the position near the large-diameter outer peripheral edge portion 104, the distances between the extending portion 106 and the guide surface 107 in the small-diameter outer peripheral edge portion 105 and the rotation center line L4 are continuous. The extension 106 and the guide surface 107 gradually approach the rotation center line L4.

  Referring to FIGS. 4, 10, and 12, the tension pulley side guide portion 102 is configured by an outer peripheral edge portion provided on the winding side of the chain C in the tension pulley 82 over the formation range in the circumferential direction. A first engagement return guide portion 110 and a disengagement prevention portion 111 provided on the side of the tension pulley 82 in the forward rotation direction A0 relative to the engagement return guide portion 110 to prevent the chain C from coming off from the tension pulley 82. Have

  A first engagement return guide portion 110 that engages a tension pulley 82 with a later-described detachment portion C12 that is a portion of the chain C that is axially deviated from the raceway surface P2 of the tension pulley 82 is provided on the tension pulley side guide portion 102. The outer peripheral edge portion is formed by being inclined and bent in a direction away from the track surface P2 in the axial direction to the left in the radial direction of the tension pulley 82, and the tension pulley side guide portion 102 is tensioned in the axial direction. This is an extended portion that extends to the left from the portion facing the pulley 82. The engagement return guide portion 110 is an inclined surface formed of a conical surface facing outward in the radial direction, in other words, an inclined surface inclined in a direction away from the track surface P2 toward the left as it goes outward in the radial direction. And a guide surface 112 made of Further, the end 112a closest to the tension pulley 82 in the axial direction on the guide surface 112 is located on the innermost side of the guide surface 112 in the radial direction, and the diameter of the portion of the chain C engaged with the tension pulley 82 is It is substantially the same position as the inner edge in the direction, that is, the inner edge C4a of the winding portion C4 in the radial direction.

Here, the raceway surface P2 of the tension pulley 82 is a plane that intersects a large number of teeth 82a (see FIG. 10) that are engaging portions with the chain C in the tension pulley 82 and is orthogonal to the rotation center line L5. (FIG. 12 shows one of the raceway surfaces that intersect the tooth 82a.)
The engagement returning guide portion 110 has a width W7 in the axial direction substantially equal to the width W4 of the chain C. The formation range is a positive rotation direction A0 centered on the rotation center line L5 in a side view with respect to the center plane P3 including the rotation center line L4 of the guide pulley 72 and the rotation center line L5 of the tension pulley 82. The angle θ1 and the angle θ2 in the reverse rotation direction are set to be substantially equal to each other, and as a whole, the angle around the rotation center line L5 is set to an obtuse angle. Further, the disengagement preventing portion 111 extends outward in the radial direction from the engagement return guide portion 110, and the tension pulley side guide portion 122 in the second arm portion 120 outward in the radial direction from the winding portion C4. Are connected to each other by a rivet 85 as a connecting portion.

  Referring to FIGS. 9, 10, and 11, the second arm portion 120 includes a fan-shaped guide pulley-side guide portion 121 formed in a circumferential range including the winding portion C3 of the chain C in the guide pulley 72; A plate in which a fan-shaped tension pulley side guide portion 122 formed in a circumferential range including the winding portion C4 of the chain C in the tension pulley 82 and a connecting portion 123 for connecting both guide portions 121 and 122 are integrally formed. Shaped member.

The guide pulley side guide portion 121 has an outer peripheral edge portion 124 provided in a range from the winding side to the unwinding side of the chain C in the guide pulley 72. In the outer peripheral edge portion 124 that is in a position overlapping with the entire entire portion of the winding portion C3 in a side view, the outer peripheral edge 124 of the guide pulley 72 is directed radially outward to a position radially outward from the rotation locus 72c. As a result, an inclined surface 125 that is inclined in the direction away from the track surface P1 in the axial direction is formed. Further, the inclined surface 125 is further formed on the edge 123a of the connecting portion 123 on the winding side of the chain C in the guide pulley 72. Also, it is continuously formed up to a position overlapping the tension pulley 82 in plan view.

  The outer peripheral edge portion 124 is larger in diameter than the large-diameter outer peripheral edge portion 104 of the first arm portion 100, and the leading edge 124 a in the radial direction connected to the inclined surface 125 is a guide for the peripheral wall 80 a of the spring accommodating portion 80. The cylindrical surface has the same diameter as the surface 80b, and is in the same position as the guide surface 80b of the spring accommodating portion 80 in the radial direction. Therefore, the distance d2 from the rotation center line L4 to the guide surface 80b and the leading edge 124a is equal, and the distance d1 from the rotation center line L4 to the guide surface 107 is smaller than the distance d2. Further, the connecting portion 123 constitutes a detachment preventing portion that prevents the chain C from detaching to the right from the guide pulley 72 and the tension pulley 82.

  4, 10, and 12, the tension pulley side guide portion 122 has a plane perpendicular to the rotation center line L <b> 5 as a symmetry plane with respect to the tension pulley side guide portion 102 of the first arm portion 100. In the same manner as the engagement return guide portion 110, the outer peripheral edge portion is formed on the winding side of the chain C in the tension pulley 82 over the formation range in the circumferential direction. 2 and a disengagement prevention portion 131 similar to the disengagement prevention portion 111.

  The second engagement return guide portion 130 for engaging with the tension pulley 82 the disengagement portion C14 that is the portion of the chain C that is axially disengaged from the raceway surface P2 of the tension pulley 82 is the outer peripheral edge of the tension pulley side guide portion 122. The portion is formed by being inclined and bent in a direction away from the raceway surface P2 in the axial direction as it goes outward in the radial direction of the tension pulley 82, and in the tension pulley side guide portion 122, the tension pulley 82 is formed in the axial direction. It is the extension part extended rightward rather than the part which opposes. The engagement return guide portion 130 is inclined in the radial direction, that is, an inclined surface formed outwardly in a conical surface, in other words, in the direction away from the track surface P2 to the right in the axial direction as going outward in the radial direction. And a guide surface 132 made of an inclined surface. Further, the end 132a closest to the tension pulley 82 in the axial direction on the guide surface 132 is located on the innermost side of the guide surface 132 in the radial direction, and is the inner edge of the winding portion C4 engaged with the tension pulley 82. It is almost the same position as C4a.

  The engagement returning guide portion 130 has a width W8 in the axial direction substantially equal to the width W4 of the chain C. The formation range is the same as that of the engagement return guide 110. Further, the disengagement preventing portion 131 extends outward in the radial direction from the engagement return guide portion 130.

  Further, the engagement return guide portions 110 and 130 are configured such that the distance between the engagement return guide portions 110 and 130 in the axial direction gradually decreases toward the disengagement prevention portions 111 and 131 in the forward rotation direction A0. And tapered guide portions 110a and 130a.

  Next, for example, when the shift operation is performed when the bicycle B is in a reverse state or a stopped state and the speed change sprockets 41 to 47 are reversely rotated or stopped, that is, the speed change sprockets 41 to 47 are not rotating forward. The extending portion 106, the peripheral wall 80a of the spring accommodating portion 80, and the chain C guiding function of the pair of engagement return guide portions 110 and 130 will be described.

  Referring to FIGS. 3, 4, and 10 to 12, when the speed change operation mechanism 60 is operated when the speed change sprockets 41 to 47 are not rotating forward and a speed change operation to a higher speed shift position is performed. As a result of the operation of the parallel link mechanism 73 of the derailleur 70, the guide pulley 72 and the tension pulley 82 move to the right together with the holder H and the arm R, and the winding portions C3 and C4 of the chain C in the guide pulley 72 and the tension pulley 82 are moved. While the guide pulley 72 and the tension pulley 82 move to the right, the chain C winding part of the transmission sprockets 41 to 47 does not move to the right, and the chain C winding part of the drive sprocket 32 also guides Since it does not move to a position corresponding to the pulley 72 and the tension pulley 82, the winding portions C3 and C4 are connected by the connecting portion 103 or the disengagement preventing portion 111. It moves to the left from the portion that is prevented from moving to the left, and is disengaged from the raceway surfaces P1, P2 from the vicinity of the connecting portion 103 or the disengagement preventing portion 111. In other words, it is disengaged from the guide pulley 72 or the tension pulley 82. Sometimes.

  At this time, the guide pulley 72 of the disengagement part which is the disengaged part of the chain C with the vicinity of the connection parts 103, 123 or the disengagement prevention parts 111, 131 as the start parts C11a, C12a is shown in FIG. As indicated by the dotted line, the disengagement part C11 rides on the extension part 106 or the guide surface 107, and for the tension pulley 82, for example, as shown by the two-dot chain line in FIG. Or ride on the guide 112.

  In this state, the extending portion 106 positions a portion of the separating portion C11 closer to the winding side of the guide pulley 72 radially outward from the rotation locus 72c of the guide pulley 72, and the driver can move the crankshaft 12 to the crankshaft 12. When the speed change sprockets 41 to 47 are rotated in the forward direction by driving them in the forward rotation direction A0, the separation portion C11 riding on the extension portion 106 slides on the guide surface 107 by the tension of the chain C at that time. Are moved toward the raceway surface P1 and then guided so as to engage with the guide pulley 72.

  In addition, the extended portion 106 of the small-diameter outer peripheral edge portion 105 of the extended portion 106 is used for the shift sprocket after the shift, such as when the shift operation is performed over a plurality of stages in the shift operation to the higher speed shift position. Even when the difference between the outer diameter and the outer diameter of the speed change sprocket before shifting is large, it contributes to securing a state in which the disengagement portion C11 rides on the extension portion 106, as shown by a one-dot chain line in FIG. For this reason, the extension part 106 is separated from the extension part 106 by the extension part 106 as compared with the case where the distance from the rotation center line L4 in this part is the same as the extension part 106 in the large-diameter outer peripheral edge 106. Thus, it is possible to realize a state in which the separation portion C11 is more reliably riding on the extension portion 106.

On the other hand, the engagement return guide portions 110 and 130 position the entire disengagement portion C12 outward in the radial direction from the rotation locus 82c of the outermost peripheral end of the tension pulley 82, and the driver rotates the crankshaft 12 in the normal rotation direction. When the speed change sprockets 41 to 47 are rotated forward by driving to A0 or the like, the detachment portion C12 moves toward the track surface P2 due to the tension of the chain C and then engages with the tension pulley 82. invite.

  Further, when the speed change operation mechanism 60 is operated when the speed change sprockets 41 to 47 are not rotating forward and a speed change operation is performed to a lower speed speed change position, the guide link 72 and the tension are operated by the parallel link mechanism 73. The pulley 82 moves to the left, and the winding portions C3 and C4 of the chain C in the guide pulley 72 and the tension pulley 82 move to the left together with the guide pulley 72 and the tension pulley 82. 47, the chain C winding part does not move to the left, and the chain C winding part of the drive sprocket 32 does not move to a position corresponding to the guide pulley 72 and the tension pulley 82. However, the connecting portion 123 or the disengagement preventing portion 131 moves to the right from the portion that is prevented from moving rightward by the connecting portion 123 or the disengagement preventing portion 131. May deviate from the track surface P2.

  At this time, for the guide pulley 72 among the detached portions, for example, the detached portion C13 rides on the peripheral wall 80a or the guide surface 80b of the spring accommodating portion 80 as shown by a two-dot chain line in FIG. For example, as shown by a two-dot chain line in FIG. 12, the disengaging part C14 rides on the engagement return guide part 130 or the guide surface 132.

  In this state, the peripheral wall 80a positions the portion of the separating portion C13 near the winding side of the guide pulley 72 radially outward from the rotation locus 72c of the guide pulley 72, and the chain due to the forward rotation of the crankshaft 12. Due to the tension of C, the disengagement part C13 riding on the peripheral wall 80a slides on the guide surface 80b and moves toward the track surface P1, and thereafter guides it to engage with the guide pulley 72. Further, since the width W6 of the peripheral wall 80a is larger than the width W3 of the extending portion 106, the peripheral wall 80a can be used when a speed change operation is performed over a plurality of stages in a speed change operation to a lower speed shift position. Even when the difference between the outer diameter of the speed change sprocket after the speed change and the outer diameter of the speed change sprocket before the speed change is large, it contributes to securing the state where the disengaging part C13 rides on the peripheral wall 80a. For this reason, it is possible to realize a state in which the separation portion C13 rides on the peripheral wall 80a more reliably without being detached from the peripheral wall 80a.

  On the other hand, the engagement return guide portion 130 positions the entire disengagement portion C14 outward in the radial direction with respect to the rotation locus 82c of the tension pulley 82, and the disengagement portion C14 due to the tension of the chain C due to the forward rotation of the crankshaft 12. Is moved toward the raceway surface P2 and then guided to engage with the tension pulley 82.

  As described above, when the guide pulley 72 and the tension pulley 82 are moved in any direction in the axial direction in accordance with the speed change operation, the disengaging parts C11 and C12 are respectively connected to the extending part 106 and the engagement return guide. The guide pulley 72 and the tension pulley 82 are guided to return to the engaged state, and the disengagement portions C13 and C14 are guided to the peripheral wall 80a and the engagement return guide portion 130, respectively. And the state of engagement with the tension pulley 82 is restored. Therefore, the extending portion 106 and the peripheral wall 80a of the spring accommodating portion 80 constitute an engagement return means for engaging the detaching portions C11 and C13, which are separated from the raceway surface P1 of the guide pulley 72, with the guide pulley 72.

Next, operations and effects of the embodiment configured as described above will be described.
When the crankshaft 12 is driven in the forward rotation direction A0 by the driver, or when the bicycle B is moving forward with the crankshaft 12 rotating backward or stopped, the derailleur is operated by operating the speed change operation member 61. The holder H of 70, the guide pulley 72, the arm R, and the tension pulley 82 occupy the seventh speed position as the basic position shown by the solid line in FIGS. The chain C is selected and spanned between the drive sprocket 32 and the transmission sprocket 47 at the positions indicated by solid lines in FIGS. The crankshaft 12 that rotates in the forward rotation direction A0 when the driver strokes the pedal rotates the drive sprocket 32 via the one-way clutch 30, and the drive sprocket 32 is connected to the transmission sprocket 47 and the output shaft via the chain C. 15 and the drive sprocket 17 are rotationally driven at a gear ratio determined by both the sprockets 32 and 47. The drive sprocket 17 rotationally drives the driven sprocket 18 and the rear wheel Wr via the chain 19.

  When the speed change operation member 61 is operated so as to select a lower speed shift sprocket 41 to 46, for example, the speed change sprocket 41, as an operating sprocket in order to switch the speed change position from the basic position, the inner cable 62b As a result, the parallel link mechanism 73 of the derailleur 70 is operated, and the holder H, the guide pulley 72, the arm R, and the tension pulley 82 are axially leftward and radially outward with respect to the rotation center line L3. And occupies the first speed position, which is the shift position indicated by the two-dot chain line in FIGS. Then, the tension of the chain C that moves to the left together with the guide pulley 72 and the tension pulley 82 moves the drive sprocket 32 to the left in the axial direction with respect to the main shaft 12a of the crankshaft 12, and the drive sprocket 32 is shown in FIG. It occupies the position indicated by the two-dot chain line in FIG. At this time, the chain C is looped over the transmission sprocket 41 and is connected to the drive sprocket 32 via the chain C.

  Further, when the speed change operating member 61 is operated so as to select the speed change sprockets 42 to 47 at higher speed relative to the first speed position, the parallel link mechanism 73 of the derailleur 70 is operated by the inner cable 62b. The parallel link mechanism 73 moves the holder H, the guide pulley 72, the arm R, and the tension pulley 82 to the right in the axial direction and radially inward with respect to the rotation center line L3, together with the guide pulley 72 and the tension pulley 82. The tension of the chain C moving to the right moves the drive sprocket 32 to the right with respect to the main shaft 12a, and at the same time, the chain C is wound around the selected transmission sprockets 42-47.

  In this way, the chain C is switched between the transmission sprockets 41 to 47 by the derailleur 70 that operates in accordance with the speed change operation by the speed change operation mechanism 60, and the selected operation sprocket and the chain C are driven. Bicycle B travels at a gear ratio determined by sprocket 32.

  Then, for example, when the bicycle B is in a reverse state or a stopped state and the speed change sprockets 41 to 47 are rotating backward or stopped, that is, when the speed change sprockets 41 to 47 are not rotating forward, the speed change operation mechanism 60 performs the speed change operation. When this is done, the chain C may be disengaged from the raceway surface P1 of the guide pulley 72 or the raceway surface P2 of the tension pulley 82, and separation parts C11, C12, C13, C14 may be formed.

  In such a case, the engagement return means for engaging with the guide pulley 72 the disengagement parts C11 and C13 of the chain C deviated from the raceway surface P1 of the guide pulley 72 is the left of the raceway surface P1 of the guide pulley 72 in the axial direction. Each of the extending portion 106 and the peripheral wall 80a extending in the axial direction in a direction away from the raceway surface P1 and the peripheral wall 80a of the spring accommodating portion 80. The disengagement parts C11 and C13 that ride on the peripheral wall 80a slide toward the raceway surface P1 by sliding the extension part 106 and the peripheral wall 80a, respectively, by the tension of the chain C when the speed change sprockets 41 to 47 rotate forward. Later, the guide pulley 72 is guided to be engaged.

As a result, the chain C is disengaged from the raceway surface P1 due to the guide pulley 72 and the tension pulley 82 being moved in the axial direction by the speed change operation when the speed change sprockets 41 to 47 are rotated in reverse or stopped. Even when the guide pulley 72 and the tension pulley 82 are moved in any axial direction by the extending portion 106 or the peripheral wall 80a constituting the engagement return means, the detaching portions C11 and C13 are 106 or sliding on the guide surfaces 107 and 80b of the peripheral wall 80a, and then guided by the extension 106 or the peripheral wall 80a so as to re-engage with the guide pulley 72, the transmission sprockets 41 to 47 rotate in the forward direction. Sometimes, the disengagement parts C11 and C13 are engaged between the guide pulley 72 and the first and second arm parts 100 and 120, and the diameter of the guide pulley 72 is smaller than the rotation locus 72c of the guide pulley 72. Inward direction Etc. is prevented Rukoto allows travel of the chain C. Therefore, for example, even if the shifting operation is performed when the bicycle B is moving backward and the transmission sprockets 41 to 47 are rotating in the reverse direction, the tube is clogged between the transmission sprockets 41 to 47 and the guide pulley 72 (that is, No stagnation of the tube C occurs, and the chain C reliably returns to the engaged state with the guide pulley 72 when the transmission sprockets 41 to 47 rotate forward.
As a result, it is easy for the disengagement parts C11 and C13 to return to the engaged state with the guide pulley 72, and the speed change sprockets 41 to 47 are not rotated forward such as when the speed change sprockets 41 to 47 are rotating in the reverse direction. The speed change operation can be performed in any rotational state of the speed change sprockets 41 to 47 including the case, and the speed change can be executed based on the speed change operation.

  The holder member includes first and second holder portions 76 and 77 that rotatably support the guide pulley 72 via a support portion 78, and a tension that is supported by the support portion 78 of the holder H and applies tension to the chain C. First and second arm portions 100 and 120 that rotatably support the pulley 82 via a support portion 84 are provided. The extension portion 106 is integrally formed with the first arm portion 100, and the peripheral wall 80a includes a tension pulley 82. Since the peripheral wall 80a of the spring accommodating portion 80 that accommodates the tension spring 83 that generates a resilient force that presses the chain C against the chain C, the extending portion 106 and the peripheral wall 80a are members that support the tension pulley 82, respectively. Since one arm portion 100 and the spring accommodating portion 80 are provided, there is no need to prepare a dedicated member constituting the extending portion 106 and the peripheral wall 80a, so the number of parts of the transmission T including the engagement return means Increase is suppressed Cost of the transmission T can be reduced.

  Further, the extended portion 106 formed by bending is formed so as to have a guide surface 107 that smoothly continues to the surfaces 104b and 105b facing the guide pulley 72 at both outer peripheral edge portions 104 and 105, Since the detachment portion C11 can smoothly move on the guide surface 107 and return to the engaged state with the guide pulley 72, the detachment portion C11 can be quickly and reliably returned to the engaged state. As a result, the speed and reliability of execution of the shift are improved.

  The transmission sprockets 41 to 47 are arranged so that the outer diameter sequentially increases to the left in the axial direction, and the extending portion 106 and the peripheral wall 80a are respectively arranged on the left side and the right side with respect to the raceway surface P1. The guide surface 107 on which the separation portion C11 can ride on the extended portion 106 is located at a position where the distance d1 from the rotation center line L4 of the guide pulley 72 is smaller than the guide surface 80b on which the separation portion C13 can ride on the peripheral wall 80a. As a result, when the guide pulley 72 moves to the left, the interference between the extension 106 and the transmission sprockets 41 to 47 is eliminated, so that the reliability of the transmission operation is ensured, and in addition, the transmission sprocket 41 to Since 47 and the guide pulley 72 can be arranged close to each other, the transmission T can be reduced in size, and the certainty of the speed change operation is improved and a smooth speed change is possible.

  The extending portion 106 is continuously provided from the guide pulley side guide portion 101 to a position where it overlaps the tension pulley 82 in a side view at the connecting portion 103. The width W3 in the axial direction of the extending portion 106 is equal to the chain Since the extension portion 106 functions as a reinforcing rib of the first arm portion 100 by being substantially equal to the width W4 in the axial direction of C, the rigidity of the first arm portion 100 that supports the tension pulley 82 is increased, and Since the guide function for returning the disengagement part C11 to the engaged state with the guide pulley 72 is ensured, the width of the first extension part 106 in the axial direction can be reduced. The protruding portion 106 can be reduced in size, the sprocket group 40 and the guide pulley 72 can be disposed close to each other in the axial direction, and the transmission T can be reduced in the axial direction.

  The arm R includes a first arm portion 100 and a second arm portion 120 that are respectively disposed on both sides in the axial direction of the raceway surfaces P1 and P2 of the guide pulley 72 and the tension pulley 82. An extension portion 106 is provided, a peripheral wall 80a of the spring accommodating portion 80 is provided adjacent to the second arm portion 120 in the axial direction, and a second arm disposed between the guide pulley 72 and the peripheral wall 80a in the axial direction. Since the distance d2 from the rotation center line L4 of the guide pulley 72 is the same as that of the guide surface 80b of the peripheral wall 80a, the detachment portion C13 has the detachment portion C13 as the second arm. Without being obstructed by the portion 120, the guide member can be smoothly guided on the peripheral wall 80a and moved on the guide surface 80b to return to the engaged state with the guide pulley 72. The quickness and certainty of return of Rapidity and certainty of rows is increased. Further, since the inclined surface 125 is formed on the outer peripheral edge portion 124 of the guide pulley side guide portion 121 of the second arm portion 120, the detaching portion C13 that has moved on the guide surface 80b is engaged with the guide pulley 72. It becomes easier.

  The width W3 of the extending portion 106 is substantially equal to the width W5 occupied in the axial direction by two transmission sprockets adjacent in the axial direction, and the axial width W8 of the peripheral wall 80a is larger than the width W3 of the extending portion 106. Due to the large size, the extending portion 106 and the peripheral wall 80a ensure a guiding function for returning the disengaging portions C11 and C13 to the engaged state with the guide pulley 72, and then the axial direction of the first extending portion 106 The width W3 can be reduced, so that the extension portion 106 can be reduced in the axial direction, and the transmission sprockets 41 to 47 and the guide pulley 72 can be arranged close to each other in the axial direction. Therefore, the transmission T can be downsized in the axial direction. Further, in the peripheral wall 80a, even when the movement width of the detaching portion C13 in the axial direction is large, the detaching portion C13 is surely climbed on the peripheral wall 80a so that the detaching portion C13 is engaged with the guide pulley 72. Since the return can be performed, the certainty of returning the disengagement portion C13 to the engaged state is improved, and as a result, the certainty of executing the shift is improved.

  The extending portion 106 of the small-diameter outer peripheral edge portion 105 is inward in the radial direction and closer to the rotation center line L4 than the extending portion 106 of the large-diameter outer peripheral edge portion 104. In the shifting operation to the position, even when the difference between the outer diameter of the speed change sprocket after the speed change and the outer diameter of the speed change sprocket before the speed change is large, the detachment portion C11 does not come off from the extension portion 106. Since the detachment portion C11 can be returned to the engaged state with the guide pulley 72 so as to surely run over the extension portion 106, the reliability of the return portion C13 to return to the engaged state is improved, and consequently The certainty of execution of shifting is improved.

  The first and second arm portions 100 and 120 are engaged with the tension pulley 82 on the winding side of the chain C in the tension pulley 82 and the detaching portions C12 and C14 of the chain C separated from the raceway surface P2 of the tension pulley 82. Engagement return guide portions 110 and 130 are provided. The engagement return guide portions 110 and 130 position the entire disengagement portions C12 and C14 outward in the radial direction from the rotation locus 82c of the tension pulley 82, and also disengagement. The parts C12 and C14 are guided to engage with the tension pulley 82 after moving toward the raceway surface P2 by the tension of the chain C.

  As a result, when the transmission sprockets 41 to 47 are not rotating forward, such as when the transmission sprockets 41 to 47 are stopped, particularly when the transmission sprockets 41 to 47 are stopped, the tension pulley 82 is moved in the axial direction by the transmission operation. Even if the chain C is disengaged from the raceway surface P2 due to the movement, the disengagement guide portions 110 and 130 cause the disengagement portions C12 and C14 of the chain C to be guided to the engagement return guide portions 110 and 130. As a result, the engagement with the tension pulley 82 is restored, so that the disengagement portions C12 and C14 are engaged between the tension pulley 82 and the first and second arm portions 100 and 120, or the tension pulley 82 side. Thus, the chain C is prevented from being positioned radially inward from the rotation locus 82c of the tension pulley 82, and the chain C can be run. As a result, the disengagement portions C12 and C14 that are disengaged from the raceway surface P2 of the tension pulley 82 by the speed change operation are guided by the engagement return guide portions 110 and 130 and are reengaged with the tension pulley 82, so that the chain C can travel. Therefore, it becomes easy for the disengaging parts C12 and C14 to return to the engaged state with the tension pulley 82, and the speed change sprocket including the stop state of the speed change sprockets 41 to 47 can be changed even in the rotation state where the speed change sprocket is not rotating normally. The operation can be performed, and the shift can be executed based on the shift operation.

  The derailleur 70 is a guide pulley 72 for guiding a chain C wound around one operating sprocket selected from the transmission sprockets 41 to 47, and rotatably supports the guide pulley 72 and moves in the axial direction together with the arm R. The arm R includes a pair of arm portions 100 and 120 disposed on both sides of the tension pulley 82 and the guide pulley 72 in the axial direction. Tension pulley side guide portions 102 and 122 that prevent the pulley 82 from detaching the chain C from the pulley 82 and guide pulley side guide portions 101 and 121 that are supported by the holder H are formed. The axial distance W1 between the pulley side guide portions 101 and 121 is larger than the axial distance W2 between the tension pulley side guide portions 102 and 122.

  As a result, the bending rigidity of the guide pulley side guide portions 101 and 121, which is a portion where the force for moving the arm R in the axial direction acts from the derailleur 70, can be increased, and thus the weight can be reduced. Further, by reducing the axial distance between the tension pulley side guide portions 102 and 122 in the arm R, the tension pulley side guide portions 102 and 122 can be disposed close to the tension pulley 82, so that the engagement is possible. The release portions C12 and C14 guided by the return guide portions 110 and 130 can be reliably returned to the engaged state with the tension pulley 82, and the return portions C12 and C14 can be reliably returned to the engaged state. Improves.

  The range of formation of the engagement return guide portions 110 and 130 in the circumferential direction is such that the forward rotation direction A0 and the reverse rotation direction of the tension pulley 82 centered on the rotation center line of the tension pulley 82 in a side view with respect to the center plane P3. In the range where the angles θ1 and θ2 are substantially the same, the formation range in the circumferential direction of the engagement return guide portions 110 and 130 around the center plane P3 can be sufficiently secured. The return to the engaged state with the tension pulley 82 is facilitated, and the reliability of the return portions C12 and C14 to the engaged state with the tension pulley 82 is improved. In addition, since the point of action of the force applied to the engagement return guide portions 110, 130 by the disengagement portions C12, C14 contacting the engagement return guide portions 110, 130 can be close to the center plane P3, the force Since the torque acting on each arm portion 100, 120 can be reduced, it is not necessary to enlarge each arm portion 100, 120 and increase its weight in order to increase the torsional rigidity of each arm portion 100, 120. The arm parts 100 and 120 can be reduced in weight.

  The arm R includes a pair of arm portions 100 and 120 that are disposed on both sides of the tension pulley 82 in the axial direction and in which engagement return guide portions 110 and 130 are formed, and each of the engagement return guide portions 110 and 130. Has guide surfaces 112 and 132 that extend in the axial direction in the direction away from the raceway surface P2 while contacting with the detaching portions C12 and C14, and the end portions 112a and 132a that are closest to the tension pulley 82 in the axial direction on the guide surfaces 112 and 132, respectively. Since 132a is substantially the same position as the inner peripheral edge C4a of the chain C engaged with the tension pulley 82, the detaching portions C12 and C14 can easily ride on the guide surfaces 112 and 132, so that the detaching portions C12 and C14 Since the start portions C12a and C14a are positions near the forward rotation direction A0 of the tension pulley 82 in the engagement return guide portions 110 and 130 and in the vicinity of the disengagement prevention portions 111 and 131, from the unwinding side of the drive sprocket 32 Starting parts C12a, C14a at sites as far as possible , And the degree of twisting of the chain C due to the movement of the tension pulley 82 in the axial direction is mitigated, and the resistance force from the chain C during the shifting operation is reduced. As a result, the resistance force from the chain C due to the twist of the chain C is reduced, so that the speed change operation is facilitated.

  The first case portion 21 of the transmission T includes a winding portion C1 of the chain C that engages the transmission sprocket 41 that is adjacent to the case 20 in the axial direction among the transmission sprockets 41 to 47, and a side view. Is provided with a protruding portion 56 that restricts the movement of the chain C in the axial direction in a direction approaching the first case portion 21, and the protruding portion 56 is brought into contact with the chain C by the chain C from the transmission sprocket 41. By preventing the chain C from coming off, the protruding portion 56 prevents the chain C from moving in the axial direction beyond the speed change sprocket 41 when the speed change operation is performed on the speed change sprocket 41, and the chain C is released from the speed change sprocket 41. In order to prevent the chain C from coming off, the position setting in the axial direction of the chain C or the guide pulley 72 corresponding to the shift position based on the shift operation is highly accurate. Therefore, the chain C is prevented from being detached from the speed change sprocket 41 by an abrupt speed change operation with a simple structure.

  Since the projecting portion 56 is integrally formed with the first case portion 21 so as to project toward the winding portion C1 in the axial direction, it is not necessary to prepare a dedicated member constituting the projecting portion 56. The number of parts and the cost of the device T are reduced, and the transmission device T is further reduced in weight.

  The first case portion 21 is provided with an inner rib 57 extending outward in the radial direction of the speed change sprocket 41 from the protrusion 56 so as to protrude in the axial direction, and the top surface 57a of the inner rib 57 in the axial direction protrudes. Since the portion 56 is in substantially the same position as the top surface 56d that restricts movement in the axial direction by contact with the chain C, the inner rib 57 further increases the rigidity of the first case portion 21 and the protruding portion 56. Even when it swells outward in the radial direction, the swelled portion is prevented from moving in the axial direction beyond the protruding portion 56, so that the chain disengagement preventing effect is further improved.

  Since the projecting portion 56, the inner rib 57 and the outer rib 58 are integrally formed on the first case portion 21 made of a plate material, the rigidity of the first case portion 21 is improved.

Further, since the projecting portion 56 is provided with the second portion 56b, the chain C can move the transmission sprocket 41 even during the shifting operation to the transmission sprocket 41 in the state where the stay portion C2 is formed in the chain C. The protrusion 56 prevents the shaft C from moving in the axial direction, and the chain C does not come off the transmission sprocket 41.
Hereinafter, an example in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration.
The case of the transmission T may be made of synthetic resin. The case forms a sealed storage chamber in which the transmission mechanism M1, the derailleur 70, and the tensioner 74 are stored. For example, the case covers at least the left side of the sprocket group 40 in the axial direction. For example, a storage chamber that is open to the outside air may be formed.

  The extending part 106 or the guide surface 107 may be inclined so as to extend in the axial direction in a direction away from the track surface P1 as it goes outward in the radial direction. Further, the extending portion 106 may be integrally formed with the first arm portion 100 by cutting or casting, and the engagement return guide portions 110 and 130 are cut into the first arm portion 100 or the second arm portion 120, respectively. It may be integrally formed by taking out or casting. The engagement return guide portions 110 and 130 or the guide surfaces 112 and 132 may extend in parallel to the rotation center line L5.

The outer peripheral edge portion 124a of the second arm portion 120 may be at a position where the distance from the rotation center line L4 is smaller than the distance d2.
The protrusion may be partially formed in the circumferential direction or the radial direction.
In the above embodiment, the common sprocket is constituted by the drive sprocket 32 and the transmission sprockets 41 to 47 are constituted by the driven sprockets. However, the plurality of transmission sprockets are constituted by the plurality of drive sprockets, and the speed change between the transmission sprockets. The common sprocket over which the chain for use is stretched may be constituted by a driven sprocket.
The sprocket group may be provided on an output shaft provided coaxially with the rotation center line of the rear wheel, and the sprocket group may be constituted by an output driven sprocket. The transmission device T may be provided in a machine other than a bicycle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention and is a schematic left side view of a bicycle including a transmission to which the present invention is applied. It is a figure which shows the II arrow view of FIG. 3, and a part in a cross section in the state which removed the 2nd case part of the transmission of FIG. The solid line indicates the arm at the highest speed shift position, and the two-dot chain line indicates the arm at the lowest speed shift position. It is the III-III sectional view taken on the line of FIG. 2, and is a figure which shows a cross section about a part of derailleur. The solid line indicates the arm at the highest speed shift position, and the two-dot chain line indicates the arm at the lowest speed shift position. FIG. 4 is a sectional view taken along line IV-IV in FIG. 2, and a part of the derailleur is a sectional view taken along line IVa. The solid line indicates the arm at the highest speed shift position, and the two-dot chain line indicates the arm at the lowest speed shift position. It is the VV sectional view taken on the line of FIG. FIG. 5 is a side view of a main part of the case of the transmission of FIG. 1 and is a view taken in the direction of arrow VI in FIG. 4. It is a principal part side view of the case of the transmission of FIG. 1, and is a VII arrow line view of FIG. It is the VIII-VIII sectional view taken on the line of FIG. It is a principal part enlarged view of FIG. The solid line indicates the arm at the highest speed shift position, and the two-dot chain line indicates the arm at the lowest speed shift position. (A), (B) is each a side view of a pair of arms with which the derailleur of the transmission of FIG. 1 is provided, and is a view taken along arrow X in FIG. The solid line indicates the arm at the highest speed shift position, and the two-dot chain line indicates the arm at the lowest speed shift position. It is the schematic of the holder and arm with which the derailleur in the XI arrow view of FIG. 10 is equipped. It is the schematic of the arm with which the derailleur in the XII arrow view of FIG. 10 is equipped.

Explanation of symbols

12 ... Crankshaft, 15 ... Output shaft, 20 ... Case, 32 ... Drive sprocket, 41-47 ... Shift sprocket, 56 ... Projection, 57, 58 ... Rib, 60 ... Shifting operation mechanism, 70 ... Derailleur, 72 ... Guide Pulley, 76, 77 ... Holder part, 80 ... Spring accommodating part, 80a ... Peripheral wall, 82 ... Tension pulley, 100, 120 ... Arm part, 104, 105, 124 ... Outer peripheral edge part, 106 ... Extension part, 107 ... Guide Surfaces 110, 130 ... engagement return guides 112, 132 ... guide surfaces,
B: Bicycle, T: Transmission, F: Body frame, M1: Transmission mechanism, M2: Shift switching mechanism, C: Chain, C11, C12, C13, C14: Detachment parts P1, P2: Track surface, P3: Center plane .

Claims (4)

A plurality of speed change sprockets arranged in the axial direction and a changing mechanism for changing the chain between the plurality of speed changing sprockets in accordance with a speed change operation. The changing mechanism applies tension to the chain. In the transmission including an arm that rotatably supports the tension pulley, and the arm moves in an axial direction by a speed change operation,
The arm is provided with an engagement return guide portion that engages the separation portion of the chain that is detached from the raceway surface of the tension pulley with the tension pulley on the winding side of the chain in the tension pulley.
The engagement return guide portion positions the entire disengagement portion radially outward from the rotation locus of the outermost peripheral end of the tension pulley, and the disengagement portion is directed toward the track surface by the tension of the chain. Guide it to engage with the tension pulley after moving ,
The arm includes a pair of arm portions arranged on both sides of the tension pulley in the axial direction,
Each arm portion is provided with the engagement return guide portion,
Each of the engagement return guide portions has a guide surface that extends in the axial direction in a direction away from the raceway surface while being in contact with the disengagement portion,
An end portion of the guide surface that is closest to the tension pulley in the axial direction is substantially the same position as an inner peripheral edge of the chain engaged with the tension pulley . The switching mechanism includes a guide pulley that guides the chain wound around one operating sprocket selected from the plurality of transmission sprockets, and rotatably supports the guide pulley and is axially moved together with the arm. A movable holder,
The both arm portions are arranged on both sides of the tension pulley and the guide pulley in the axial direction ,
Each arm part is formed with a tension pulley side guide part for preventing the chain pulley from coming off in the tension pulley, and a supported part supported by the holder,
The transmission according to claim 1, wherein an interval in the axial direction between the two supported portions is larger than an interval in the axial direction between the two tension pulley side guide portions. The range in which each engagement return guide portion is formed in the circumferential direction is such that the rotation pulley centerline of the tension pulley is viewed in a side view with respect to a center plane including the rotation centerline of the tension pulley and the rotation centerline of the guide pulley. 3. The transmission according to claim 2, wherein the transmission is within a range where substantially the same angle is obtained in the forward rotation direction and the reverse rotation direction of the tension pulley as a center. The width of each engagement return guide portion in the axial direction is substantially equal to the width of the chain,
Each of the arm portions has a disengagement prevention portion that is provided closer to the positive rotation direction of the tension pulley than the engagement return guide portion and prevents the chain from coming off from the tension pulley,
Each detachment prevention part extends outward in the radial direction from the engagement return guide part,
The detachment preventing portions of the both arm portions are connected to each other by a connecting portion at a radially outer side than a winding portion of the chain in the tension pulley,
Each of the engagement return guide portions has a tapered guide portion so that an interval between the both engagement return guide portions in the axial direction gradually decreases toward the both come-off prevention portions in the positive rotation direction of the tension pulley. transmission according to any one of the preceding claims, characterized 3 to have a.

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