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, having a shift lever (8) movable in opposite directions from a home position; a takeup reel (5) connected to one end of the wire for winding up the wire (520) with movement in one direction of the shift lever; a one-way transmission mechanism (100) for transmitting only movement in one direction of the shift lever to the takeup reel (5); position retaining teeth and a position retaining pawl for retaining the takeup reel (5) 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 (16) and pawl (17), and allowing the takeup reel to rotate in the wire unwinding direction. The retention canceling cam mechanism (400) includes a release element 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 (8) is connected to the takeup reel (5) through a one-way mechanism (100) which transmits only movement in the wire winding direction. Consequently, the takeup reel (5) 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 (5) 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 apparatus according to the preamble of the main claim. 2. DESCRIPTION OF THE RELATED ART Conventional bicycle speed control systems of the type noted above are known (Japanese Patent Publication Kokai No. 1990-88384 and U.S. Patent No. 5,012,692,) 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. Further a bicycle with a speed control apparatus is known (GB-A-2012893). Finally such a combination according to the preamble of the main claim is known (WO 90/ 09396). Hereby a break lever an the control member of the speed control apparatus are pivotable about parallel axes which are essentially parallel to a longitudinal direction of the handlebar. This construction does not allow to check an operational error with respect to a change speed direction. Additionally the control member cannot be used without ease from the human engineering point of view. An objekt 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 features of the main claim. Other features are claimed in the subclaims. In the speed control system according to the present invention 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. Other features and advantages of the present invention will be apparent from the description of the preferred embodiments to be had with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a bottom view of a speed control apparatus in a first embodiment of the present invention, Fig. 2 is a view in vertical section of the apparatus shown in Fig. 1, Fig. 3 is a section taken on line A of Fig. 2, Fig. 4 is an exploded view showing principal components of the apparatus shown in Fig. 1, Figs. 5 through 7 are views in cross section showing different operative states of the apparatus shown in Fig. 1, DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described next with reference to Figs. 1 through 7. Fig. 1 shows a bicycle speed control apparatus 1 embodying the present invention and secured to a bottom position adjacent a grip 510 of a handlebar extending transversely of a bicycle. A shift lever 8 extends substantially along an undersurface of the grip 510 to be pivotable in the fore and aft direction of the bicycle. When the shift lever 8 is pressed by a thumb of the cyclist to pivot forward from home position to a second shift end, a change speed wire 520 extending from a rear derailleur is wound up to effect change speed in a positive direction. When the shift lever 8 is pressed by a first finger of the cyclist to pivot rearward from the home position to a first shift end, the change speed wire 520 is unwound to effect change speed in a negative direction. Numeral 2 denotes a brake lever bracket acting also as a mounting device for the speed control apparatus 1. The change speed wire 520 is an inner wire of a release cable, which is surrounded by an outer sleeve 530. As shown in Fig. 2, the change speed apparatus 1 includes a stationary member 3 fixed to the bracket 2 which is shown only in outline described by a phantom line, and a support shaft 4 extending downwardly from the stationary member 3. The support shaft 4 carries a takeup reel 5 for winding the wire 520 thereon, a pawl supporting sleeve 6, a release element 7 and the shift lever 8 coaxially arranged in the stated order. The support shaft 4 is formed as a spline shaft not rotatable relative to the stationary member 3. As shown in Fig. 2, the takeup reel 5 includes a wire engaging section 5a and a wire winding section 5b formed peripherally thereof. The takeup reel 5 is rotatable relative to the support shaft 4, and urged in a wire unwinding direction by a first spring 9 mounted between the takeup reel 5 and stationary member 3. Further, the takeup reel 5 includes a bush 5c as an integral part thereof surrounding the support shaft 4. The shift lever 8 is pivotably supported at a proximal end thereof on the support shaft 4 through a spacer 10. The shift lever 8 is urged in the wire unwinding direction by a second spring 12 relative to a first stopper plate 11 mounted on the support shaft 4 not to be rotatable relative thereto. The shift lever 8 includes a plastic tab 8a formed on a distal end thereof. As shown in Figs. 2 and 3, the release element 7 is rotatably supported on the support shaft 4 through a spacer 13. The release element 7 is urged in the wire winding direction by a third spring 15 relative to a second stopper plate 14 mounted on the support shaft 4 not to be rotatable relative thereto. As shown in Fig. 3, and particularly an enlarged fragmentary view therein seen from above, the release element 7 defines a stopper recess 7a in a peripheral position thereof for receiving a stopper projection 12a extending from the second stopper plate 14 to limit a range of rotation of the release element 7. Further, the release element 7 includes a positioning projection 7b extending from a peripheral position thereof for contacting the shift lever 8 to determine the home position of the lever 8. The shift lever 8 is operatively connected to the takeup reel 5 through a one-way transmission device 100 as shown in Figs. 2 and 3. The one-way transmission device 100 includes a plurality of one-way teeth 16 defined peripherally of the bush 5c of the takeup reel 5, a one-way pawl 17 pivoted to a pin 17a connected to the shift lever 8 for engaging the teeth 16, and a spring 17b for urging the one-way pawl 17 to an engaging position. With this one-way transmission device 100, when the shift lever 8 is turned in the wire winding direction, the takeup reel 5 is rotated in the same direction, the shift lever 8 being capable of returning in the wire unwinding direction independently of the takeup reel 5. The stopper projection 12a extending from the second stopper plate 14 includes a guide portion 12b for guiding the one-way pawl 17 in disengaging from the one-way teeth 16 when the shift lever 8 is in the home position. As shown in Figs. 2, 4 and 5, a position retaining device 200 includes a position retaining pawl 18 pivoted to a pawl shaft 6a extending parallel to the support shaft 4 from the pawl supporting sleeve 6 mounted on the support shaft 4, and position retaining teeth 20 defined on an inside peripheral wall of the bush 5c for engagement with the pawl 18. A restricting device 300, which will be described later, is a mirror image of the position retaining device 200, and includes a restricting pawl 19 pivoted to a pawl shaft 6b extending from the pawl supporting sleeve 6, and restricting teeth 22 defined on an inside peripheral wall of the bush 5c for engagement with the pawl 19. The takeup reel 5 is retained by the position retaining device 200 in stagewise stopping positions depending on winding lengths of the wire 520. The position retaining pawl 18 is urged by a pawl spring 18a to an engaging position. The position retaining pawl 18 and position retaining teeth 20 have an engaging structure and pawl shaft location determined so as to allow rotation in the wire winding direction of the takeup reel 5 by operation of the shift lever 8, and to prevent backward rotation in the wire unwinding direction of the takeup reel 5 and retain the takeup reel 5 in the stopping positions. The position retention by the position retaining device 200 may be canceled by turning the shift lever 8 in the wire unwinding direction beyond the home position. The first shift end mentioned hereinbefore is an end of shift of the shift lever 8 in the unwinding direction from the home position, while the second shift end is an end of shift thereof in the winding direction from the home position. In this embodiment, the shift lever 8 in the shift from the first shift end to the second shift end describes a shifting locus substantially on a single plane, and is operable linearly. The takeup reel 5 retained in position by the position retaining device 200 is releasable by a retention canceling device 400. As shown in Fig. 2, 4 and 5, the retention canceling device 400 includes a projection 18b extending from the position retaining pawl 18, and the release element 7 defining a cam bore 21 for receiving the projection 18b. When the release element 7 is rotated in the wire unwinding direction by the shift lever 8, the cam bore 21 guides the projection 18b to forcibly swing the position retaining pawl 18 out of engagement with the position retaining teeth 20. The takeup reel 5 freed by the retention canceling device 400 rotates in the wire unwinding direction under the force of the first spring 9. The rotation in the unwinding direction of the takeup reel 5 during this unwinding operation is limited to a predetermined amount by the restricting device 300. The restricting device 300 includes, besides the restricting pawl 19 and restricting teeth 22, a projection 19a extending from the restricting pawl 19, and a restricting cam bore 23 defined in the release element 7 for receiving the projection 19a. When the release element 7 is caused by the shift lever 8 to rotate in the wire unwinding direction, the restricting cam bore 23 guides the projection 19a to forcibly swing the restricting pawl 19 for engagement with one of the restricting teeth 22. In this way, the restricting pawl 19 is moved into a locus for engaging one of the restricting teeth 22 before the position retention by the position retaining device 200 is canceled. Consequently, the rotation in the unwinding direction of the takeup reel 5 is limited to less than one pitch of the position retaining teeth 20. In Fig. 2, numeral 24 denotes a bearing for the outer sleeve 530. Numeral 25 denotes a lock nut for retaining the various components on the support shaft 4. Numerals 26 and 27 denote washers. The way in which the change speed apparatus 1 constructed as above operates will be described next with reference to Figs. 5 through 7. These drawings show sections of the apparatus 1 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. 4. Referring to Figs. 5 and 6, change speed in the wire winding direction is effected by pressing the shift lever 8 toward the second shift end, i.e. downward in the drawings, with a thumb. At this time, a force is transmitted through the one-way transmission device 100 to rotate the takeup reel 5 in the winding direction, i. e. clockwise in the drawings. When the cyclist stops pressing the shift lever 8 with the thumb, the takeup reel 5 stops in position by the action of the position retaining device 200, whereas the shift lever 8 returns independently of the takeup reel 5 by the freeing action of the one-way transmission device 100 and stops at the home position by contact with the positioning projection 7b. It is of course possible to effect multistep change speed in a single operation by shifting the shift lever 8 a corresponding amount. Referring to Fig. 7, change speed in the wire unwinding direction is effected by pressing the shift lever 8 toward the first shift end, i.e. upward in the drawing, with a first finger. At this time, the release element 7 having the positioning projection 7b rotates in the unwinding direction to cancel the action of the position retaining device 200 and to operate the restricting device 300 to limit the backward rotation in the unwinding direction of the takeup reel 5 within one pitch of the position retaining teeth 20. When the cyclist stops pressing the shift lever 8 with the first finger, the release element 7 returns in the winding direction under the force of the third spring 15 to cancel the action of the restricting device 300 and to cause the position retaining device 200 to retain the takeup reel 5 in a position one step backward in the unwinding direction. At the same time, the shift lever 8 returns to the home position. The foregoing embodiments may be modified as follows: The shift lever 8 in the first embodiment may have a wide tab 8a with respect to the pivoting direction to facilitate the wire unwinding operation with the first finger. In the first embodiment, the change speed apparatus 1 has the shift lever disposed under the handlebar 500. Except where the bicycle has a flat handlebar, operation of the shift lever 8 may be facilitated by attaching the change speed apparatus 1 such that the shift lever 8 is located at the opposite side of a surface contacted by the interdigital pads of the hand holding the grip. In the first embodiment, the position retaining teeth 20 and restricting teeth 22 are formed on the inside walls of the bush 5c of the takeup reel 5. However, these teeth may be formed on outer peripheries, or upper or lower surfaces of the takeup reel 5. 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 bicycle with a speed control apparatus which is provided at a handlebar of the bicycle and controls a change speed device throug a change speed wire, said speed control apparatus comprising: a control member (8,38,79) movable between a first shift end and a second shift end; takeup means (5,36,75) connected to one end of said change speed wire, and movable in a wire (520 winding direction and in a wire unwinding direction, said takeup means being urged in said wire unwinding direction; one-way transmission means (100,101,103) for transmitting only movement toward said second shift end of said control member to said takeup means, said takeup means being movable in said wire winding direction by the movement toward said second shift end; position retaining means (200,210,220) for retaining said takeup means in a plurality of winding positions; and retention canceling means (400,410,420) for canceling retention of said takeup means by said position retaining means and allowing said takeup means to move in said wire unwinding direction; said control member has a hone position provided between said first shift end and said second shift end; and said retention canceling means includes a release element (7,33,78) movable between a release position and a non-release position, and urging means (15,46,85) for urging said release element to said non-release position, said release element being movable to said release position by movement of said control member from said home position toward said first shift end characterized in that said control member (8),(38),(79) and said take-up means (5),(36),(75) are both pivotable about a pivot shaft (4) and in that said pivot shaft (4) extends away from said handle bar and is substantially perpendicular to a longitudinal direction of said handle bar. A speed control system as claimed in claim 1 or 2 characterized in that said control member (8,38,79) is formed as a pivotable lever disposed in a region below a handle grip of the bicycle. A speed control system as claimed in any one of claims 1 to 3, characterized in that said control member (8,38,79) is formed as a grip rotatably mounted on the handlebar of the bicycle.

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