Speed control apparatus for a bicycle

Abstract: A bicycle speed control apparatus according to this invention comprises a wind-up control device including a take-up element (21) for winding a speed control cable, and a position maintaining mechanism (3) for maintaining the take-up element in position. The control device is operable to effect change speed by rotating the take-up element (21) for winding the cable. The present invention is characterized in that the position maintaining mechanism (3) is operable to maintain the take-up element (21) in a plurality of change speed positions and in overshift positions displaced from the change speed positions in a cable winding direction, respectively. The invention further provides a position maintenance canceling device (4) operable to release the take-up element (21) maintained in position by the position main­ taining mechanism (3), and to limit an amount of rota­ tion of the take-up element (21) in the rewinding direction to one change speed position when the take-­ up element (21) has been maintained in one overshift position associated therewith.

Description: The present invention relates to a a speed change control apparatus for a bicycle according to the preamble of claim 1. A bicycle speed control apparatus as noted above is disclosed in Japanese Patent Publication Kokai No. 59-149586, for example. In this Prior publication, the position maintaining mechanism includes a friction plate to provide a pressure contact for maintaining the take-up element in a selected position. As well known in the art, a change speed operation from a small gear to a larger gear requires an overshift of the derailleur effected by operating the wind-up control device beyond a correct change speed position, which is followed by a return of the control device to the correct change speed position. With the above known construction, however, the rider must take great care in operating the wind-up control device to the overshift position and then returning the control device to the correct change speed position. This tends to take the rider's attention away from handlebar control and the like, to the detriment of a smooth bicycle run. Further, such an overshift operation needs great skill, which makes it difficult for a beginner in particular to carry out a smooth change speed operation. A speed change control apparatus according to the preamble of claim 1 is disclosed in GB-A-2 012 893. For reliably effecting an overshifting operation required in shifting from a smaller sprocket to a larger sprocket, it is not disclosed to provide the overshift regions to the speed change control apparatus where the change speed cable can be maintained to facilitate the change speed operation. An object of the present invention is to provide a speed control apparatus for a bicycle which allows even a beginner to carry out a smooth change speed operation by reliably effecting a series of overshift operations necessary in changing from a small gear to a larger gear. In order to achieve the above object, a speed control apparatus for a bicycle according to the present invention is defined by the characterizing part of the main claim. With the above construction according to the present invention, the wind-up element can be maintained in overshift positions by the position maintaining mechanism. The position maintenance canceling device releases the wind-up element maintained in position by the position maintaining mechanism, to allow the wind-up element to return in the rewinding direction, and to selectively limit a returning amount of the wind-up element to a selected position as follows: When the position maintenance canceling device is operated with the wind-up element maintained in one of the overshift positions, the returning amount is limited to the change speed position associated with this overshift position. Since the wind-up element is maintained in that position thereafter, a series of overshift operations may be carried out in a stable and reliable manner. On the other hand, when the position maintenance canceling device is operated with the wind-up element maintained in one of the change speed positions, the wind-up element is returned to and maintained in a different change speed position in the rewinding direction, thereby changing from a larger gear to a smaller gear. Thus, according to the present invention, even a beginner can carry out a return operation from an overshift position reliably and smoothly only by operating the position maintenance canceling device constructed to effect a change from a larger gear to a smaller gear. In the case of a trained rider, less care may be necessary for the return operation from an overshift position, whereby the rider can keep his or her mind on bicycle running with attention concentrated on handlebar control and the like. Other objects, features and advantages of the present invention will be apparent from the following description of a preferred embodiment. BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1 through 4 show a speed change apparatus for a bicycle according to the present invention, in which:- Fig. 1 is an enlarged partial view in section of the speed control apparatus, Fig. 2 is a reduced section taken on line 2-2 of Fig. 1, Fig. 3 is a reduced section taken on line 3-3 of Fig. 1, and Fig. 4 is a reduced section taken on line 4-4 of Fig. 1. Figs. 5 through 7 show operative states of a wind-up element 21, in which:- Fig. 5 is an explanatory view showing the wind-up element in an initial position, Fig. 6 is an explanatory view of the wind-up element in an overshift position, and Fig. 7 is an explanatory view showing the wind-up element in a selected speed position. Fig. 8 is an explanatory view showing a pawl in a disengaged position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described next with reference to the drawings. Fig. 1 shows a speed control apparatus for use mainly with a three-speed front derailleur. A fixing member 1 has a base element 15 attached to the handlebar (not shown) of a bicycle and carrying a lever axis 11. The lever axis 11 has a plurality of axial grooves 16 and a screw thread defined peripherally of a forward end portion thereof. The lever axis 11 supports a speed change control member 2 acting as a wind-up control means, a wire wind-up element 21, and a release lever 43 and a regulator 46 acting as a position maintaining and releasing means, which are mounted on the lever axis 11 in the mentioned order and retained in position by a nut 5 screwed to the screw thread. This speed control apparatus is mounted adjacent a grip of the handlebar with the lever axis 11 extending downwardly so that the rider can control the change speed lever 2 and release lever 43 with the thumb of his or her hand holding the grip. As described later, the regulator 46 forms part of a rotation limiting mechanism in combination with the wind-up element 21. Reference 21a in the drawings denotes a wire hook provided for the wind-up element 21 to engage one end of a control wire, and reference 6 denotes a fixing screw. The wind-up element 21 is formed separately from a control portion of the speed change control member 2 and rotatably supported on the lever axis 11. The wind-up element 21 defines a plurality of feed teeth 22 arranged at a small pitch around an outer periphery thereof, which feed teeth 22 act as a first engaging portion. The speed change control member 2 pivotally supports a feed pawl 23 acting as a first engaging member to engage the feed teeth 22 for transmitting an operating force acting in a wire winding direction of the speed change control member 2 to the wind-up element 21. A spring 24 is mounted between the feed pawl 23 and a pawl axis for constantly urging the feed pawl 23 toward the feed teeth 22. These elements constitute a one-way mechanism. The wind-up element 21 has two engaging projections 26 defined with a 180-degree phase difference on one axial end face thereof. A return spring 10 is mounted between the wind-up element 21 and lever axis 11 for aiding return of the wind-up element 21. A lever spring 25 is mounted between the speed change control member 2 and lever axis 11 for returning the speed change control member 2 in a wire rewinding direction after a swing operation thereof. A stopper 12 and a contact piece 27 are provided between an axial bore wall of the speed change control member 2 and the lever axis 11 for stopping the speed change control member 2 at an operation initiating position (hereinafter referred to as an original position). The position maintaining means 3 includes engaging teeth 31 defined on a lower peripheral wall of the wind-up element 21 to act as a second engaging portion, and a stopper pawl 32 acting as a second engaging member for engaging the engaging teeth 31 and holding the take-up element 21 against rotation in the wire rewinding direction. The stopper pawl 32 is pivotally supported on a pawl axis 14 extending upwardly and parallel to the lever axis 11 from an upstanding piece 13 provided on the fixing member 1. A pawl spring 33 is mounted between the stopper pawl 32 and upstanding piece 13 for disengaging the pawl 32 from the engaging teeth 31 when the change speed lever 2 is swung in the wire winding direction. These engaging teeth 31 are engageable with the stopper pawl 32 at a smaller pitch than the pitch corresponding to each proper speed stage. The release member 43 pivotably supported on the lever axis 11 includes a displacer piece 41 for sweeping aside both the feed pawl 23 and stopper pawl 32, and a cam surface 42 for raising the regulator 46. The displacer piece 41 is disposed between the feed pawl 23/stopper pawl 32 and the feed teeth 22/engaging teeth 31. When the release member 43 is swung in the same direction as rotation of the wire wind-up element 21, the displacer piece 41 contacts the feed pawl 23 and stopper pawl 32 and causes these pawls 23 and 32 to pivot away from the teeth 22 and 31 as shown in Fig. 8. The rotation limiting mechanism includes a pressure projection 44 slidable on the cam surface 42, an engaging projection 26 acting as a third engaging portion, and the limiting member 46 having a limiting projection 45 acting as a third engaging member engageable with the engaging projection 26. The regulator 46 is supported not to be rotatable but axially movable on the lever axis 11. A spring 47 is mounted between the regulator 46 and wind-up element 21 for urging the regulator 46 away from the wind-up element 21. Thus, when the release lever 43 is pressed in the wire winding direction, the regulator 46 moves toward the wind-up element 21 by means of the cam surface 42 and pressure projection 44 to advance the limiting projection 45 into a locus of movement of the engaging projection 26. When the release lever 43 is freed, the spring 47 causes the release lever 43 through the cam surface 42 to return in the wire rewinding direction. Figs. 1 through 5 show a low speed state wherein a multistage front gear device is in a small gear position. The speed change control member 2 is urged by the lever spring 25 and stopped at the original position with the contact piece 27 of the speed change control member 2 contacting the abutment 12 of the lever axis 11. To operate the speed change control member 2 from the original position to a larger gear, the rider may place the thumb of the hand holding the grip on the control portion of the speed change control member 2, and swing the member 2 an overshift amount exceeding an amount corresponding to one change speed stage in the wire winding direction (clockwise) from the position shown in Fig. 2. Then the operating force of the speed change control member 2 is transmitted to the wind-up element 21 through the feed pawl 23 engaged with the feed teeth 22 of the wind-up element 21. As a result, the wind-up element 21 rotates the overshift amount clockwise, pulling the control wire and overshifting a chain guide of the derailleur to change to an intermediate larger gear. When the speed change control member 2 is released, the stopper pawl 32 engages the engaging teeth 31 of the wind-up element 21 thereby to prevent rotation of the wind-up element 21 in the wire rewinding direction. Thus the wind-up element 21 is positively maintained in the overshift position. The speed change control member 2 returns to the original position (counterclockwise in Fig. 2) under the force of lever spring 25. The speed change control member 2 is stopped at the original position by a contact between the contact piece 27 and abutment 12 as shown in Fig. 2 to be ready for a next operation. To cancel the overshift after the above change speed operation, the rider may press the release member 43 with his thumb from the position shown in Figs. 2 and 3 in a direction indicated by arrows in Figs. 2 and 3. This causes the release member 43 to slightly pivot clockwise, which in turn causes the regulator 46 through the cam surface 42 to move toward the wind-up element 21, thereby advancing the limiting projection 45 into the locus of movement of the engaging projection 26 of the wind-up element 21. Subsequently, the displacer piece 41 contacts the feed pawl 23 and stopper pawl 32 and disengages these pawls from the teeth 22 and 31. Since the engaging projection 26 of the wind-up element 21 contacts the limiting projection 45 as shown in Fig. 7, the wind-up element 21 under the force of return spring 10 returns an amount less than the pitch of each speed stage in the rewinding direction from the overshift position. When the release member 43 is released, the release member 43 returns under the force of spring 47, whereby the engaging projection 26 disengages from the limiting projection 45. The wind-up element 21 makes a slight return rotation under the force of return spring 10 while the pawls 23 and 32 move into engagement with the teeth 22 and 31. The pawls 23 and 32 engage the teeth 22 and 31 with the engaging projection 26 displaced from the limiting projection 45, whereby the wind-up element 21 stops at the proper position. The wind-up element 21 is then prevented from rotation in the wire rewinding direction and positively maintained at the proper position. To change from the larger high speed gear back to the small low speed gear, the rider may press the release member 43 with the thumb in the direction indicated by the arrows in Figs. 2 and 3. This causes the displacer piece 41 to contact the feed pawl 23 and stopper pawl 32 and disengage these pawls from the teeth 22 and 31. The wind-up element 21 under the force of return spring 10 rotates back to the original position from the proper position corresponding to the change speed position. When the release member 43 is released, the wind-up element 21 is positively maintained at the proper position by the same function as in the foregoing instance of overshift cancellation. A change from the intermediate larger gear to the largest gear may be effected by operating the speed change control member 2 release member 43 in the same way as for the change from the small gear to the intermediate gear. The engaging projection 26 may be provided at a plurality of locations corresponding to proper change speed stages, respectively. Various modifications of the present invention are listed hereunder. I. In the foregoing embodiment the wind-up element 21 is formed separately from the speed change control member 2, but these components may be formed integrally. Then, there is no need for the lever spring 25, feed teeth 22 or feed pawl 23. II. In the foregoing embodiment, the wind-up element 21 is returned in the wire rewinding direction by the return spring 10. Alternatively, the return spring of the deraileur may be utilized to return the wind-up element 21. Thus, the return spring 10 mounted between the wind-up element 21 and fixing member 1 is dispensable. III. Although the position maintaining means 3 has been described as having the stopper pawl 32 and engaging teeth 31, this mechanism may include a roller and engaging recesses engageable with the roller, instead. In this case, for example, the engaging recesses may be provided on overshift and proper positions of the wind-up element 21, with fixing member 1 carrying the roller and a spring for urging the roller toward the recesses. IV. In the position maintenance canceling means 4 the release member 43 can comprise a push button construction having a cam surface and operable with an axial push of the lever axis 11 to control the feed pawl 23 and stopper pawl 32.

Claims: A speed change control apparatus for a bicycle comprising: a speed change control member (2) operatively connected to a derailleur through a speed control cable; a wind-up element (21) for winding up said speed control cable through pivotal movement of said speed change control member (2), said wind-up element (21) being urged to a cable rewinding direction; position maintaining means (3) for maintaining said wind-up element (21) in a plurality of speed change positions; position maintenance canceling means (4) having a release member (43) for releasing said wind-up means maintained in position by said position maintaining means, said position maintenance cancelling means returning said wind-up means to a next speed change position in said rewinding direction when said wind-up means is maintained in one of said speed change positions; characterized in that said position maintaining means (3) being operable of maintaining said wind-up element (21) in overshift regions correspondingly defined in regions beyond said respective speed change positions, and said position maintenance cancelling means (4) returning said wind-up element (21) to a corresponding speed change position when said wind-up elements (21) is maintained in one of said overshift regions. A speed change control apparatus for a bicycle as set forth in claim 1, characterized in that said wind-up element (21) includes a pivotal axis (10) and is pivotable about said pivotal axis, said speed change control member (2) being pivotable about said pivotable axis (11). A speed change control apparatus for a bicycle as set forth in claim 2, characterized in that said apparatus includes first engaging means (22, 23) for transmitting pivotal movement of said speed change control member (2) to said wind-up element (21). A speed change control apparatus for a bicycle as set forth in claim 3, characterized in that said first engaging means includes a one-way clutch (22, 23) for transmitting pivotal movement of said speed change control member 2) only in a winding direction to said wind-up element (21). A speed change control apparatus for a bicycle as set forth in one of claims 1 to 4 characterized in that said position maintaining means (3) is formed as a pivotal pawl (32), said apparatus further including second engaging means defined between said pivotal pawl (32) and said wind-up element (21) for selectively interconnecting therebetween. A speed change control apparatus for a bicycle as set forth in claim 5 characterized in that said second engaging means includes a plurality of engaging teeth (31) defined in said wind-up element (21) and said pivotal pawl (32) engagable with one of said engaging teeth (31). A speed change control apparatus for a bicycle as set forth in claim 6 characterized in that said plurality of engaging teeth (31) produce a region engageable with said pawl element (32) correspoding to each overshift region. A speed change control apparatus for a bicycle as set forth of claims 1 to 4 characterized in that said position maintaining means (3) includes a limiting member (46) mounted on said pivotal axis (11) to be relatively unrotatable therewith and axially slidable, said limiting member (46) further including third engaging means (26, 45) defined betweeen said wind-up element (21) and said limiting member (46) for releasing engagement therebetween with an operation of said release member (43). A speed change control apparatus for a bicycle as set forth in claim 8 characterized in that said third engaging means ( 26, 45) inlcudes limiting projections (45) defined in said limiting member (46) and engaging projections (26) defined in said wind-up element (21), said position maintenance cancelling means (4) capable of of shifting said limiting projection (45) into a locus of pivotal movement of engaging projection through a movement of said release member (43) whereby said position maintenance cancelling means (4) release said wind-up element (21) maintained in position. A speed change control apparatus for a bicycle as set forth in one of the claims 1 or 3 to 9, characterized in that said release member (43) includes a displacer piece (41) for releasing engagement by said first (23, 22) and second (32, 31) engaging means.

Inventors: NAGANO MASASHI, NAGANO, MASASHI
Applicants: SHIMANO INDUSTRIAL CO, SHIMANO INDUSTRIAL COMPANY LIMITED
Application year: 1990
Main classification: B62M25
IPC codes: B62M25