Abstract:
A position release mechanism for a bicycle control device comprises a positioning unit that is adapted to be biased in a first direction; a position maintaining mechanism that maintains the positioning unit in a plurality of predetermined positions; and a position releasing mechanism that moves in a position releasing direction, wherein the position releasing mechanism is operatively coupled to the position maintaining mechanism so that the positioning unit moves through at least two of the plurality of predetermined positions in the first direction in response to a progressive movement of the position releasing mechanism in the position releasing direction.

Description:
BACKGROUND OF THE INVENTION 
   The present invention is directed to bicycles and, more particularly, to various features of a shift control device for a bicycle transmission. 
   Conventional shift control devices for bicycle transmissions typically include a lever or twist grip that is rotated in two directions. One rotational direction is used to upshift the bicycle transmission, and the other rotational direction is used to downshift the bicycle transmission. The bicycle transmission moves by an amount proportional to the movement of the shift control device in either direction. 
   More advanced shift control devices use ratchet and pawl mechanisms and two levers to control a wire winding member that controls the bicycle transmission. An example of such a shift control device is shown in U.S. Pat. No. 5,400,675. More specifically, a downshift lever is used to operate the wire winding member in a downshifting direction, and an upshift lever is used to operate the wire winding member in an upshifting direction. Pushing the downshift lever from a home position to a downshift position moves the wire winding member in a downshifting direction by a proportional amount until a downshift ratchet and pawl mechanism maintains the wire winding member in the newly selected position, which may correspond to up to speed steps. As a result, moving the downshift lever from the downshift position back to the home position does not have any effect on the position of the wire winding member (except for play in the components). Pushing the upshift lever from a home position to an upshift position moves the wire winding member in an upshifting direction (opposite the downshifting direction) through a two-stage process. In the first stage, the upshift lever is pushed from the home position to the upshift position, and the wire winding member moves in the upshifting direction by an amount determined by the releasing action of an upshift ratchet and pawl mechanism. In the second stage, the upshift lever is allowed to move from the upshift position back to the home position. In this case, the upshift ratchet and pawl mechanism allows the wire winding member to move the remaining amount required by the upshifting operation and thereafter stops the rotation of the wire winding member to complete the shift. However, only one speed step change may be achieved with such a construction. 
   In any event, known dual-lever shift control devices have the ability to operate the bicycle transmission through multiple speed steps in either the upshifting direction or the downshifting direction using a single operation of one of the levers. However, such an operation is not possible for both levers. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to various inventive features of a bicycle shift control device. In one embodiment, a position release mechanism for a bicycle control device comprises a positioning unit that is adapted to be biased in a first direction; a position maintaining mechanism that maintains the positioning unit in a plurality of predetermined positions; and a position releasing mechanism that moves in a position releasing direction, wherein the position releasing mechanism is operatively coupled to the position maintaining mechanism so that the positioning unit moves through at least two of the plurality of predetermined positions in the first direction in response to a progressive movement of the position releasing mechanism in the position releasing direction. 
   Additional inventive features will become apparent from the description below, and such features alone or in combination with the above features may form the basis of further inventions as recited in the claims and their equivalents. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an oblique view of a combined brake/shift control device; 
       FIG. 2  is a partially exploded view of the combined brake/shift control device shown in  FIG. 1 ; 
       FIG. 3  is an exploded view of the shift control portion of the combined brake/shift control device shown in  FIG. 1 ; 
       FIGS. 4(A)–4(D)  are views illustrating the operation of the combined brake/shift control device in a downshifting direction; and 
       FIGS. 5(A)–5(F)  are views illustrating the operation of the combined brake/shift control device in an upshifting direction. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
     FIG. 1  is an oblique view of a combined brake/shift control device  10  attached to the forwardly curved portion of a handlebar H of well known construction. Brake/shift control device  10  includes a base member  14  attached to handlebar H, a brake lever  18  pivotably coupled to base member  14 , and a shift control lever  22  pivotably coupled to brake lever  18 . Brake lever  18  is coupled to base member  14  in a manner that allows brake lever  18  to pivot in a forward and rearward direction relative to handlebar H as well as in a lateral direction relative to handlebar H. Shift control lever  22  pivots in a lateral direction relative to handlebar H and brake lever  18 . 
     FIG. 2  is a partially exploded view of the combined brake/shift control device  10 . A screw  30  extends through an opening  34  in an attachment band  38 , through an opening  42  in base member  14 , through a square washer  46  and threadingly engages a nut  50  to attach attachment band  38  and thereby base member  14  to handlebar H in a known manner. A pivot shaft  54  is mounted to mounting ears  66  formed on base member  14 , and a frame  74  is mounted to pivot shaft  54  through bushings  78  and  82  so that frame  74  can pivot in the forward and rearward direction. A coupling shaft  150  ( FIG. 3 ) having splines  154  and threaded ends  158  and  162  is used to connect brake lever  18  to frame  74  so that brake lever  18  can pivot in the forward and rearward direction around pivot shaft  54 . A biasing member in the form of a spring  166  having first and second ends  170  and  174  is wound around pivot shaft  54  such that spring end  170  engages frame  74  and spring end  174  engages base member  14  so that frame  74  and hence brake lever  18  are biased in a direction away from handlebar H. Mounting posts  100  of a brake cable terminating member  102 , each surrounded by a bearing  104  and a retaining collar  108 , are rotatably supported by respective hooks  112  formed on frame  74 . Brake cable terminating member  102  includes a brake cable terminating opening  116  for receiving the inner wire and cable end bead of a brake control bowden cable in a known manner. 
     FIG. 3  is an exploded view of the shift control portion of the combined brake/shift control device  10 . Coupling shaft  150  extends through a bearing washer  178 , through a splined opening  182  in frame  74 , and through a splined opening  186  in a square washer  190 . A nut  194  is screwed onto the threaded end  158  of coupling shaft  150  so that coupling shaft  150  is nonrotatably mounted to frame  74 . A bearing collar  204  formed on frame  74  extends through an opening  198  in a drive plate  202  so that drive plate  202  is rotatably supported relative to frame  74 . Drive plate  202  functions as a position setting member in a manner discussed below. A screw  206  extends through an opening  210  in a coupling ear  214  and screws into a threaded opening  218  in brake lever  18  so that brake lever  18  and drive plate  202  rotate integrally around bearing collar  204 . A brake lever return spring  217  having spring ends  219  and  220  surrounds bearing collar  204 . Spring end  219  is disposed in an opening  221  in frame  74 , and spring end  220  is disposed in an opening  223  in drive plate  202  so that drive plate  202 , and hence brake lever  18 , is biased in a clockwise direction in  FIG. 3 . A drive pawl shaft  222  extends through an opening  224  in drive plate  202  and rotatably supports a drive pawl  228  having a drive pawl tooth  229 . Drive pawl  228  is retained on drive pawl shaft  222  by a clip  230 . A drive pawl spring  234  having spring ends  238  and  242  surrounds drive pawl shaft  222 . Spring end  238  engages drive pawl  228 , and spring end  242  engages a spring abutment  246  on drive plate  202  so that drive pawl  222  is biased in the counterclockwise direction. 
   Coupling shaft  150  also extends through a splined opening  250  in a position maintaining plate  254  so that position maintaining plate  254  is nonrotatably supported on coupling shaft  150 . Position maintaining plate  254  includes a drive pawl control surface  255  having a radially inner surface  256  and a radially outer surface  257  that cooperate with drive pawl  228  in a manner described below. A position maintaining pawl shaft  258  extends through an opening  262  in position maintaining plate  254  and rotatably supports a position maintaining pawl  266 . Position maintaining pawl  266  includes a position maintaining portion or member  267 , a position release portion or member  268 , and a motion limiting portion or member  269 . Position maintaining pawl  266  is retained on position maintaining pawl shaft  258  by a clip  270 . A position maintaining member biasing mechanism in the form of a position maintaining pawl spring  274  having spring ends  278  and  282  surrounds position maintaining pawl shaft  258 . Spring end  278  engages position maintaining pawl  266 , and spring end  282  engages a side edge  286  of position maintaining plate  254  so that position maintaining pawl  266  is biased in a counterclockwise direction. 
   Coupling shaft  150  extends through a splined opening  410  formed in a cylindrical portion  402  of a bushing  398  which abuts against position maintaining plate  254 . Cylindrical portion  402  of bushing  398  extends through an opening  288  in a wire takeup drum  290  so that wire takeup drum  290  is rotatably supported relative to coupling shaft  150 . Wire takeup drum  290  includes a wire winding groove  294  and a cable terminating opening  298  for receiving the cable end bead of a shift control wire (not shown) in a known manner. A biasing mechanism in the form of a return spring  302  having spring ends  306  and  310  surrounds the cylindrical portion  402  of bushing  398 . Spring end  306  is disposed in an opening  314  formed in position maintaining plate  254 , and spring end  310  is disposed in an opening (not shown) in wire takeup drum  290  so that wire takeup drum  290  is biased in a clockwise (first) direction. In this embodiment, wire takeup drum  290  is integrally formed with a positioning unit  318  in the form of a positioning wheel. Positioning unit  318  includes a plurality of circumferentially disposed drive abutments in the form of drive teeth  322  and a plurality of circumferentially disposed position maintaining abutments in the form of position maintaining teeth  326 . As discussed in more detail below, drive pawl  228  engages drive teeth  322  to rotate wire takeup drum  290  counterclockwise, and position maintaining pawl  266  engages position maintaining teeth  326  to function as a position maintaining mechanism to maintain positioning unit  318  and thereby wire takeup drum  290  in one of a plurality of predetermined rotational positions. 
   Cylindrical portion  402  of bushing  398  extends through an opening  328  in a release member in the form of a release wheel  330  and through openings  334  and  338  in release pivot plates  342  and  346  that straddle release wheel  330  so that release wheel  330  and release pivot plates  342  and  346  are rotatably supported relative to coupling shaft  150  coaxially with positioning unit  318  and wire takeup drum  290 . Release wheel  330  includes a plurality of position releasing abutments in the form of release teeth  350  formed around the entire circumference thereof. Release pivot plates  342  and  346  also straddle a release control lever  354  that includes a finger contact projection  362  and a release control pawl  358  having a release control pawl tooth  360 . A pivot shaft  366  extends through respective openings  370  and  374  in release pivot plates  342  and  346  and through an opening  378  in release control lever  354  so that release control lever  354  can pivot relative to release pivot plates  342  and  346 . Release control lever  354  and release pivot plates  342  and  346  are retained to pivot shaft  366  by a clip  382 . A spring  386  having two spring ends (only spring end  390  is shown in the drawings) surrounds pivot shaft  366 . The hidden end of spring  386  engages drive plate  202 , and spring end  390  is disposed in an opening  394  in release control lever  354  so that release control lever  354  is biased in a clockwise direction relative to drive plate  202 . Finger contact projection  362  includes a rearwardly extending finger contact paddle  365  so the rider can easily move that release control lever  354  laterally. 
   Coupling shaft  150  exits splined opening  410  in bushing  398  and extends through a splined opening  414  in a spacer  418  and through a washer  422 . A nut  426  is screwed onto the threaded end  162  of coupling shaft  150  to press against a flange portion  406  of busing  398  and thereby press bushing  398  against position maintaining plate  254 . Flange portion  406  of bushing  398  also retains takeup drum  290 , release wheel  330  and release pivot plates  342  and  346  in the assembled form. 
     FIGS. 4(A)–4(D)  are views illustrating the operation of the combined brake/shift control device  10  in a downshifting direction (i.e., when the rider pushes brake lever  18  counterclockwise).  FIG. 4(A)  shows drive plate  202 , which rotates integrally with brake lever  18 , in a home position HP. In this position, position maintaining portion  267  of position maintaining pawl  266  abuts against a position maintaining tooth  326 C of positioning unit  318  because position maintaining pawl  266  is biased in the counterclockwise direction by position maintaining pawl spring  274  and positioning unit  318  is biased in the clockwise direction by return spring  302 . At the same time, drive pawl tooth  229  of drive pawl  228  rests on radially outer surface  257  of drive pawl control surface  255  so that drive pawl tooth  229  is disengaged from drive teeth  322 . 
     FIG. 4(B)  shows drive plate  202  rotated slightly counterclockwise. In this position, drive pawl tooth  229  of drive pawl  228  has moved from the radially outer surface  257  of drive pawl control surface  255  to the radially inner surface  256  of drive pawl control surface  255  because drive pawl  228  is biased on the counterclockwise direction by drive pawl spring  234 . At the same time, drive pawl tooth  229  engages a drive tooth  322 E, and position maintaining portion  267  of position maintaining pawl  266  continues to abut against positioning tooth  326 C. 
     FIG. 4(C)  shows drive plate  202  further rotated counterclockwise. In this position, drive pawl tooth  229  of drive pawl  228  has rotated positioning unit  318  counterclockwise against the biasing force of return spring  302 . At the same time, position maintaining portion  267  of position maintaining pawl  266  rides up the left side of positioning tooth  326 D and rotates position maintaining pawl  266  clockwise against the biasing force of position maintaining pawl spring  274 . Further counterclockwise rotation of drive plate  202  causes the position maintaining portion  267  of position maintaining pawl  266  to ride up and over the tip of positioning tooth  326 D. Thereafter, the position maintaining portion  267  of position maintaining pawl  266  rotates counterclockwise in accordance with the biasing force of position maintaining pawl spring  274  and enters the space between position maintaining tooth  326 D and position maintaining tooth  326 E. 
     FIG. 4(D)  shows drive plate  202  after the rider has rotated it clockwise via brake lever  18  back to the home position HP. As drive plate  202  rotates clockwise from the position shown in  FIG. 4(C) , positioning unit  318  initially rotates clockwise in accordance with the biasing force of return spring  302 , but such rotation is stopped because the position maintaining portion  267  of position maintaining pawl  266  abuts against positioning maintaining tooth  326 D Thereafter, drive pawl tooth  229  of drive pawl  228  moves to the radially outer surface  257  of drive pawl control surface  255  so that drive pawl tooth  229  again is disengaged from drive teeth  322 . 
     FIGS. 5(A)–5(F)  are views illustrating the operation of the combined brake/shift control device  10  in an upshifting direction (i.e., when the rider pushes release control lever  354  counterclockwise).  FIG. 5(A)  shows release control lever  354  in a home (first) position P 1 . In this position, position maintaining portion  267  of position maintaining pawl  266  abuts against positioning tooth  326 C (the same position shown in  FIG. 4(A) ). At the same time, release control pawl tooth  360  of release control pawl  358  is separated from the release teeth  350  on release wheel  330  as a result of the biasing force of spring  386 . 
     FIG. 5(B)  shows the components during initial counterclockwise rotation of release control lever  354  (i.e., in a position releasing (second) direction). Initially, release control lever  354  rotates counterclockwise around pivot shaft  366 , and release control pawl tooth  360  of release control pawl  358  enters the space between release teeth  350 A and  350 B. Thereafter, release control pawl tooth  360  of release control pawl  358  abuts against the side surface of release tooth  350 B. At this time, release pivot plates  342  and  346  remain stationary. 
   As shown in  FIG. 5(C) , further rotation of release control lever  354  causes release pivot plates  342  and  346  and release wheel  330  to rotate counterclockwise. This, in turn, causes a release tooth  350 H of release wheel  330  to press against position release portion  268  of position maintaining pawl  266 , thus rotating position maintaining pawl  266  clockwise. Since position maintaining portion  267  of position maintaining pawl  266  is integrally formed with position release portion  268 , position maintaining portion  267  of position maintaining pawl  266  also rides up the right side surface of position maintaining tooth  326 (C). 
   As soon as position maintaining portion  267  of position maintaining pawl  266  rides over the tip of position maintaining tooth  326 C of positioning unit  318 , positioning unit  318  rotates clockwise in accordance with the biasing force of return spring  302  as shown in  FIG. 5(D) . However, rotation of positioning unit  318  is stopped when position maintaining tooth  326 D abuts against the motion limiting portion  269  of position maintaining pawl  266 . Release tooth  350 H of release wheel  330  has maintained position maintaining pawl  266  in the clockwise position at this time. This provides for intermittent movement of positioning unit  318  in response to continued movement of release wheel  330  in the position releasing direction. As release wheel  330  continues to rotate counterclockwise and the position release portion  268  of position maintaining pawl  266  clears the tip of release tooth  350 H, the position maintaining portion  267  of position maintaining pawl  266  rotates counterclockwise in accordance with the biasing force of position maintaining pawl spring  274  and enters the space between position maintaining tooth  326 B and  326 C. Similarly, the position release portion  268  of position maintaining pawl  266  enters the space between release tooth  350 H and a release tooth  350 G. Further clockwise rotation of position maintaining pawl  266  disengages the motion limiting portion  269  of position maintaining pawl  266  from position maintaining tooth  326 D. This, in turn, allows positioning unit  318  to continue rotating clockwise until position maintaining tooth  326 B abuts against position maintaining portion  267  of position maintaining pawl  266  as shown in  FIG. 5(E) . This completes the shift operation by one speed step even though release control lever  354  has not reversed direction (i.e., has not moved back toward the home position). 
   If desired, the rider may rotate release control lever  354  back to the home position P 1  to accomplish a single shift, and then again rotate release control lever  354  counterclockwise as shown in  FIG. 5(F)  to shift the transmission by another step. In this case, a release tooth  350 G of release wheel  330  presses against position release portion  268  of position maintaining pawl  266 , thus rotating position maintaining pawl  266  clockwise. The position maintaining portion  267  of position maintaining pawl  266  rides up the right side of position maintaining tooth  326 B, and the process proceeds in the same manner as in  FIGS. 5(C)–5(E) . 
   In this embodiment, it is not necessary for the rider to return release control lever  354  to the home position P 1  after every single shift to complete the shift. Instead, continued counterclockwise rotation of release control lever  354  from the home position P 1  to an arbitrary second position P 2  (determined by the particular application) continues the clockwise rotation of release wheel  330 , thus repeating the process shown in  FIGS. 5(C)–5(E)  over and over again to complete a plurality of shifts. It is not necessary to rotate release control lever  354  back to the home position P 1  before shifting to another gear. Thus, the rider can perform a single shift or multiple shifts as desired. 
   Once the rider has shifted the desired number of speeds, the rider then may rotate release control lever  354  back to the home position P 1 . At that time, both release control lever  354  and release pivot plates  342  and  346  rotate clockwise, thus disengaging pawl tooth  360  of release control pawl  358  from release teeth  350 . Since pawl tooth  360  of release control pawl  358  disengages from release teeth  350  whenever release control lever  354  rotates clockwise, there is no corresponding clockwise movement of release wheel  330 . Thus, release wheel  330  effectively rotates in only one direction. 
   While the above is a description of various embodiments of inventive features, further modifications may be employed without departing from the spirit and scope of the present invention. For example, while multiple shifts were described in the context of upshifting, the teachings of the present invention can be applied to any system where there is provided a positioning unit that is adapted to be biased in any direction and a position maintaining mechanism that maintains the positioning unit in a plurality of predetermined positions. The shift lever need not be connected to the brake lever (e.g., it could be coupled to the base member  14 ), and the multiple shifting mechanism may be used by itself without requiring both levers to perform multiple shifts. 
   The size, shape, location or orientation of the various components may be changed as desired. Components that are shown directly connected or contacting each other may have intermediate structures disposed between them. The functions of one element may be performed by two, and vice versa. The structures and functions of one embodiment may be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the scope of the invention should not be limited by the specific structures disclosed or the apparent initial focus on a particular structure or feature.