Bicycle speed control system for controlling a change speed device through a change speed wire

Abstract: A speed control system for a bicycle for controlling a change speed device through a change speed wire (520), having a shift lever movable in opposite directions from a home position; a takeup reel (5) connected to one end of the wire for winding up the wire with movement in one direction of the shift lever (8); a one-way transmission mechanism for transmitting only movement in one direction of the shift lever to the takeup reel; position retaining teeth (16) and a position retaining pawl (17) for retaining the takeup reel in a plurality of winding positions; and a retention canceling cam mechanism (400) for canceling retention of the takeup reel by the position retaining teeth and pawl, and allowing the takeup reel to rotate in the wire unwinding direction. The retention canceling cam mechanism includes a release element (7) movable between a release position and a non-release position, and a spring for urging the release element to the non-release position. The release element is movable to the release position by movement of the shift lever from the home position in the other direction. The shift lever is connected to the takeup reel through a one-way mechanism which transmits only movement in the wire winding direction. Consequently, the takeup reel is successively shifted in the winding direction by reciprocating the shift lever on one side of the home position. When the shift lever is shifted to the other side of the home position, the takeup reel is freed from position retention by action of the release element. As a result of the release, the takeup reel urged in the wire unwinding direction rotates in the unwinding direction, thereby effecting a return through change speed stages.

Description: BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION The present invention relates to a speed control system according to the precharacterizing portion of claim 1 (cF. GB-A-2 012 893). 2. DESCRIPTION OF THE RELATED ART Conventional bicycle speed control systems of the type noted above are known from Japanese Patent Publication Kokai No. 1990-88384 and U.S. Patent No. 5,012,692, for example. These control systems include a release lever besides a shift lever, for releasing a change speed wire takeup reel from a position retaining device. Further, a spring is provided for urging the takeup reel in a wire unwinding direction in order to expedite rotation in the unwinding direction of the takeup reel after its release from the position retaining device. In such a construction, the shift lever returns to home position after each shifting operation. This feature provides the advantage of allowing the shift lever to be operated within an optimal stroke range from the human engineering point of view, even when the shift lever is operated to provide a speed many stages away from the home position. That is, the shift lever is shifted back and forth plural times to effect change speed in the wire winding direction, i.e. in a positive direction. Conversely, when effecting change speed in the wire unwinding direction, i.e. in a negative direction, the release lever is operated to release the takeup reel from the position retaining device, whereby the takeup reel automatically rotates backward. However, since the release lever is provided besides the shift lever, the cyclist could easily operate the wrong lever in a change speed operation. As a result, there is not a little chance of effecting change speed in the wrong direction. Furthermore, this type of speed control system may be disposed adjacent a grip of a handlebar. In such a case, the position of the shift lever optimal from the human engineering point of view is limited for manipulation with the thumb and finger. Consequently, where the two levers are provided, at least one must be located in a position difficult to operate. In addition, according to the above construction, the force of the spring for urging the takeup reel in the wire unwinding direction presents a resistance to turning of the shift lever in the wire winding direction. This provides the drawback of giving a heavy feeling when the cyclist operates the shift lever in the wire winding direction. SUMMARY OF THE INVENTION An object of the present invention is to provide a bicycle speed control system which is capable of checking an operational error with respect to a change speed direction, and allows a control member to be used with ease from the human engineering point of view. Another object of the invention is to realize a light and easy operation of a control member in a wire winding direction. The above objects are fulfilled, according to the present invention, by a speed control system as set forth in the introductory part hereof, comprising the features of the characterizing portion of claim 1. According to this control system, the control member is operatively connected to the takeup device through a one-way mechanism to move the takeup device only in a wire winding direction. Consequently, the takeup device is successively shifted in the winding direction by reciprocating the control member between home position and second shift end. After operating the control member to the second shift end, i.e. in the wire winding direction, the control member is returned to the home position manually or by a spring, for example. Change speed may be effected for plural speed stages by repeating the above reciprocation. When the control member is shifted from the home position to the first shift end, the takeup device is freed from position retention by action of the release element included in the retention canceling device. As a result of the release, the takeup device urged in the wire unwinding direction rotates in the unwinding direction, thereby effecting a return through change speed stages. Since the release element is urged by the urging device in the wire winding direction, the release element is restricted against rotation in the Wire unwinding direction without a releasing operation by the cyclist. Consequently, there is no chance of a releasing operation occurring inadvertently against the will of the cyclist. In the speed control system according to the present invention, as described above, the change speed device may be shifted in positive and negative directions by operating the single control member in opposite directions. This control member may be situated in a position to operate easily and reliably. Since only one control member is adequate, not only may the control member be in the form of a shift lever attached to the handlebar, but a handgrip itself may readily be adapted to act as the control member. In a preferred embodiment of the invention, the release element is connectable to the takeup means to transmit a force in the wire unwinding direction directly or indirectly to the takeup means, the urging means being operable to urge the takeup means in the wire unwinding direction through the release element This construction achieves the additional advantage of supplying an auxiliary force to lighten the change speed operation in the wire unwinding direction. Other features and advantages of the present invention will be apparent from claims 3 to 8 as well as from the description of the preferred embodiments to be had with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view in vertical section taken along a handlebar and showing a speed control apparatus in an embodiment of the present invention, Fig. 2 is an exploded view showing principal components of the apparatus shown in Fig. 1, Fig. 3 is a section taken on line B of Fig. 1, Fig. 4 is a section taken on line C of Fig. 1, and Figs. 5 through 8 are views similar to Fig. 4 and showing different operative states of the apparatus shown in Fig. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described next with reference to Figs. 1 through 8. This embodiment has the control member in the form of a grip 510. As shown in Figs. 1 and 2, a speed control apparatus 1 in this embodiment includes a first stationary member 32 mounted coaxially with a handlebar 500, and a release element 33, a guide plate 34, a feed plate 35 and a takeup reel 36 fitted on the first stationary member 32 in the stated order and retained in position by a lock ring 37. Further, a control member 38 is rotatably fitted from an extreme end of the handlebar 500. Numerals 39a and 39b in Fig. 1 denote bushes for allowing rotation relative to the first stationary member 32 of the components except the guide plate 34 which is fitted on the first stationary member 32 not to be rotatable relative thereto. As shown in Fig. 1, the control member 38 includes a handle collar 40 rotatably mounted on the handlebar 500, a dive plate 41 fitted on the collar 40 not to be rotatable, and a grip rubber 42 fitted on the collar 40. The handle collar 40 is retained in position by a second stationary member 43 rigidly connected to the first stationary member 32. As shown in Fig. 3, the control member 38 is urged by a lever-shaped neutralizing spring 44 mounted between the drive plate 41 and second stationary member 43, to return to home position after being operated in a wire winding direction. i.e. toward a second shift position, or in a wire unwinding direction. i.e. toward a first shift position. For the control member 38 to stop at the home position with a click, the second stationary member 43 carries a clicking mechanism 45 including a positioning projection 45a movable relative to and urged toward the drive plate 41, and a positioning recess 45b defined in the drive plate 41 for engagement with the projection 45a when the control member 38 is in the home position. A clicking resistance is adjustable by advancing or retracting an adjuster screw 45c. As shown in Fig. 3, the takeup reel 36 includes a wire engaging section 36a and a wire winding section 36b formed peripherally thereof. The takeup reel 36 is rotatable with the feed plate 35. As shown in Fig. 4, a return spring 46 is provided between the feed plate 35 and release element 33 for urging the release element 33 in the wire winding direction when the feed plate 35 is fixed, and urging the feed plate 35 in the wire unwinding direction when the release element 33 is fixed. Further, the release element 33 and feed plate 35 include stoppers 47a and 47b, respectively, for limiting rotation in the winding direction of the release element 33 relative to the feed plate 35 at a predetermined position. As shown in Figs. 2 through 4, the drive plate 41 of the control member 38 is operatively connected to the feed plate 35 through a first one-way transmission device 101. Further, the drive plate 41 is engageable with a second one-way transmission device 102 for transmitting drive to the release element 33. The first and second one-way transmission devices 101 and 102 transmit the drive in opposite directions. The first one-way transmission device 101 includes a plurality of first one-way teeth 48 defined peripherally of the feed plate 35, and a first one-way pawl 50 pivoted to a pawl supporting shaft 49 extending from the drive plate 41 for engaging the teeth 48. The first one-way pawl 50 is urged in a direction to engage the teeth 48. When the control member 38 is rotated toward the second shift end to wind the wire, the first one-way transmission device 101 causes the takeup reel 36 to rotate with the feed plate 35 in the wire winding direction. Subsequently, the control member 38 returns to the home position independently of the feed plate 35 by the freeing action of the first one-way transmission device 101. The second one-way transmission device 102 includes a plurality of second one-way teeth 51 defined peripherally of the release element 33, and a second one-way pawl 52 pivoted to the pawl supporting shaft 49 for engaging the releasing teeth 51. The second one-way pawl 52 is urged in a direction to engage the teeth 51. When the control member 38 is rotated from the home position toward the first shift end to unwind the wire, the second one-way transmission device 102 causes the release element 33 to rotate in the wire unwinding direction in order to cancel retention in position of the takeup reel 36 as will be described in detail later. The control member 38 is capable of returning to the home position independently of the release element 33 by the freeing action of the second one-way transmission device 102. For selective operation of the first and second one-way transmission devices 101 and 102, the guide plate 34 includes a guide portion 34a disposed between the first and second one-way pawls 50 and 52 to separate one of the pawls from the first or second one-way teeth 48 or 51. Numeral 53 in the drawings denotes a torsion coil springs for acting on both the first and second one-way pawls 50 and 52. The takeup reel 36 rotatable with the feed plate 35 is retained by a position retaining device 210 in stagewise stopping positions depending on winding lengths of the wire 520. As shown in Figs. 2 and 4, the position retaining device 210 includes a plurality of position retaining teeth 54 defined peripherally of the feed plate 35, and a position retaining pawl 55 pivoted to a pin extending from the first stationary member 32 for engaging the retaining teeth 54. The pawl 55 is urged toward an engaging position by a pawl spring 56a. The position retaining teeth 54 and pawl 55 have an engaging structure and positional relationship with the pin 56 to allow rotation in the wire winding direction of the takeup reel 36 by operation of the control member 38, and to prevent backward rotation in the wire unwinding direction of the takeup reel 36. The position retention by the position retaining device 210 may be canceled by rotating the control member 38 in the wire unwinding direction from the home position to the first shift end. The cancellation is achieved by a retention canceling device 410 which includes, besides the second one-way transmission device 102 and release element 33, a plurality of teeth 57 formed peripherally of the release element 33 and in staggered relations with the position retaining teeth 54 to act as retention canceling cams. When the release element 33 is rotated in the wire unwinding direction, the retention canceling teeth 57 forcibly swing the position retaining pawl 55 out of engagement with the position retaining teeth 54. The takeup reel 36 freed by this disengagement rotates in the wire unwinding direction under the force of the return spring 46. The rotation in the unwinding direction of the feed plate 35, and thus the takeup reel 36, during this unwinding operation is limited to a predetermined amount by a restricting device 310. The restricting device 310 comprises a construction in which, as shown in Figs. 2 and 4, the position retaining teeth 54 and retention canceling cams 57 have radially outwardly increasing heights in the wire unwinding direction, respectively, and in which each retention canceling cam 57 is higher than the position retaining tooth 54 engaged prior to a wire unwinding operation and lower than a next position retaining tooth 54 in the unwinding direction. Consequently, the rotation in the unwinding direction of the takeup reel 36 resulting from one unwinding operation is limited to one pitch of the position retaining teeth 54. In Fig. 1, numeral 58 denotes a guide element for bending the wire 520 ninety degrees to follow the handlebar 500. Numeral 59 denotes a slide bush for smoothing rotation of the control member 38 relative to the second stationary member 43. The way in which the change speed apparatus 31 in the second embodiment constructed as above operates will be described next with reference to Figs. 4 through 8. These drawings show sections of the apparatus of Fig. 1 only in a way suited to description of the functions, and are not correct drawings in the strict meaning of graphics, from which components unnecessary to the description are omitted. For constructions of the various components, reference should be made to the exploded view in Fig. 2. Change speed in the wire winding direction or positive direction is effected by holding the grip rubber 42 of the control member 38 and flexing the wrist in a direction to rotate the control member 38 from the home position to the second shift end. At this time, as shown in Fig. 5, a force is transmitted through the first one-way transmission device 101 to rotate the takeup reel 36 in the winding direction. i.e. counterclockwise in the drawing. When the cyclist stops applying the rotating force to the control member 38, as shown in Fig. 6, the takeup reel 36 stops in position by the action of the position retaining device 210. Then, the control member 38 returns independently of the takeup reel 36 to the home position with the clicking mechanism 45 engaged, under the urging force of the lever spring 44 and by the freeing action of the first one-way transmission device 101 and with the second one-way pawl 52 riding on the guide portion 34a. Change speed in the wire unwinding direction or negative direction is effected by holding the grip rubber 42 and flexing the wrist in the opposite direction to rotate the control member 38 from the home position to the first shift end. At this time, as shown in Fig. 7, a force is transmitted through the second one-way transmission device 102 to rotate the release element 33 in the unwinding direction. The position retaining pawl 55 is thereby lifted to cancel the position retention by the position retaining device 210. The takeup reel 36 rotates in the unwinding direction until the stoppers 47a and 47b contact each other since the release element 33 is connected to the control member 38 and the feed plate 35 and takeup reel 36 are freed. The return spring 46 applies an urging force to rotate the takeup reel 36 in the unwinding direction. At the same time, the return movement of the takeup reel 36 is limited within ore pitch of the position retaining teeth 54 by the restricting device 310, and position retention is effected again by the position retaining device 210. When the cyclist stops applying the rotating force to the control member 38, as shown in Fig. 8, the control member 38 returns independently of the release element 33 to the home position with the clicking mechanism 45 engaged, under the urging force of the lever spring 44 and by the freeing action of the second one-way transmission device 102 and with the first one-way pawl 50 riding on the guide portion 34a. The release element 33 does not rotate in the unwinding direction since the feed plate 35 is fixed, the return spring 46 urges the release element 33 in the winding direction, and the stoppers 47a and 47b contact each other to limit rotation of the release element 33. This avoids an inadvertent operation of the retention canceling device 410. In the foregoing embodiments, the present invention is applied for operating a rear derailleur. The present invention is equally applicable for operation of a front derailleur or a contained speed changer.

Claims: A speed control system adapted to be mounted to a handlebar of a bicycle for controlling a change speed device through a change speed wire (58) comprising: a control member (38) movable between a first shift end and a second shift end, said control member (38) having a home position provided between said first shift end and said second shift end; takeup means (36) connectable to one end of said change speed wire (58), and movable in a wire winding direction by a movement of said control member (38) toward said second shift end and in a wire unwinding direction by a movement of said control member (38) toward said first shift end, said takeup means (36) being urged in said wire unwinding direction; first one-way transmission means (101) for transmitting only movement of said control member (38) toward said second shift end to said takeup means (36); position retaining means (210) for retaining said takeup means (36) in a plurality of winding positions; and retention canceling means (410) for canceling retention of said takeup means (36) by said position retaining means (210) and allowing said takeup means (36) to move in said wire unwinding direction; said retention canceling means (410) including a release element (33) movable between a release position and a non-release position, and urging means (46) for urging said release element (33) to said non-release position, said release element (33) being movable to said release position by movement of said control member (38) from said home position toward said first shift end, characterized in that said control member (38) is adapted to surround said handlebar and to rotate substantially coaxially with an axis of said handlebar. A speed control system as claimed in claim 1 characterized in that said release element (33) is connectable to said takeup means (36) to transmit a force in said wire unwinding direction directly or indirectly to said takeup means (36), said urging means (46) being operable to urge said takeup means (36) in said wire unwinding direction through said release element (33) A speed control system as claimed in claim 1 characterized in that said first one-way transmission means (101) includes a first one-way teeth (48) rotatable in unison with said takeup means (36) and first one-way pawl (50) operatively connected to said control member (38). A speed control system as claimed in claim 1 further comprising a second one-way transmission means (102) for rotating said release element (33) in said wire unwinding direction wherein said second one-way transmission means (102) includes a second one-way teeth (51) formed on said release element (33) and a second one-way pawl (52). A speed control system as claimed in claim 3 further comprising a feed plate (35) interlocked with said takeup means (36) such that said feed plate and said takeup means (36) rotate in unison wherein said first one-way teeth (48) are formed on said feed plate (35). A speed control system as claimed in claim 5 characterized in that said position retaining means (210) includes position retaining teeth (54) formed on said feed plate (35) and a position retaining pawl (55) engageable with said position retaining teeth (54), said position retaining teeth (54) having increasingly higher height in said wire winding direction. A speed control system as claimed in claim 6 characterized in that said retention canceling means (410) includes retention canceling cams (57) which have outwardly increasing heights in said wire winding direction. A speed control system as claimed in claim 7 characterized in that relative heights of said position retaining teeth (54) and said retention canceling cams (57) define restricting means (310) for a wire unwinding operation wherein each retention canceling cam (54) is higher than a position retaining tooth (54) engaged with said position retaining pawl (55) prior to said wire unwinding operation and lower than a next retaining tooth (54) located in the wire winding direction whereby said unwinding operation is restricted to one pitch of the position retaining teeth (54).

Inventors: NAGANO MASASHI, NAGANO, MASASHI
Applicants: SHIMANO KK, SHIMANO INC.
Application year: 1991
Main classification: B62M25
IPC codes: B62M25