Abstract:
A combined gear change and brake control unit in a support body which can be fastened to a bicycle handlebar. The brake control lever and gear change control unit are carried by a support body. The gear change unit has a rotatable shaft attached to a pulley with an end portion of a derailler control cable wound thereon. The shaft is subject to a return torque that turns the shaft to release the cable. The unit has a gear change lever that controls the rotation of the shaft in a direction that winds the cable onto the pulley and a cable release button. The gear change control unit includes a ratchet mechanism that leaves the shaft free to turn by a predetermined amount in the release direction of the cable.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a combined gear change and brake control unit for a bicycle. More precisely, this invention relates to a combined unit of the type described by the Applicant in document EP 0 504 118. This document describes a combined control unit comprising a support body connected to a brake control lever pivoting around a first axis and a gear change control unit connected to the support body. The gear change control unit comprises a shaft turnable around a second axis orthogonal to said first axis and carrying a pulley on which the end portion of a control cable of a front or rear derailleur of a bicycle is wound. The rotation of the shaft in a first direction can be controlled by means of a gear change lever, which is arranged immediately behind the brake control lever, while the rotation of the shaft in a second direction can be controlled by means of a button lever, operating on a gear, which is solidly fastened to the shaft. As concerns the shaft control in said second direction, the control unit of the known kind consists of a spring retainer mechanism to withhold the shaft in a number of reference positions. The button lever is destined to co-operate with the gear solidly fastened to the shaft by means of a meshing unit, to produce the rotation of the shaft from one of said reference positions to another. 
     SUMMARY OF THE INVENTION 
     The objective of this invention is to provide a gear change control unit which is constructively more simple and cost-effective than the one described above. An additional objective of this invention is to provide a gear change control unit requiring a very limited stroke of the button lever to shift the gear. 
     According to this invention, these objectives are attained by means of a combined control unit which characteristics are described in the main claim. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This invention will be better explained by the following detailed descriptions with reference to the accompanying figure as non-limiting example, whereas: 
     FIG. 1 is a lateral partially sectioned view of a combined control unit according to this invention, 
     FIGS. 2 a ,  3   a  and  4   a  are sections according to the line II—II in FIG. 1 illustrating the operation of a unit during gear change in a first direction, 
     FIGS. 2 b ,  3   b ,  4   b  are similar sections to those shown in FIGS. 2 a ,  3   a  and  4   a  illustrating the operation of the unit during the gear change in a second direction as indicated by the directional arrows, 
     FIG. 5 is a section according to the line V—V in FIG. 2 a,    
     FIG. 6 is a lateral partially sectioned view of a second form of embodiment of the unit according to this invention, 
     FIG. 7 is a similar view to FIG. 6 illustrating a second operative position, 
     FIG. 8 is a perspective view of the part indicated by arrow VIII in FIG. 6, and 
     FIG. 9 is a plan view according to the arrow IX in FIG.  8 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to FIG. 1, numeral  10  indicates a combined gear change and brake control unit of a competition bicycle. Unit  10  essentially works as the unit described in the previous patent application EP 0 504 118 by the Applicant to which reference is made for all aspects not expressly illustrated in this description. 
     The integrated control unit  10  comprises a support body  12  with means (not illustrated) for fastening to the handlebar of a bicycle (also not illustrated). A brake control lever  14  is pivotally fastened to the support body  12  around a first axis formed by a pivot  16 . In the known way, an end of a brake control cable is anchored to an upper end of the lever  14 . 
     The support body  12  carries a gear change control unit, generally referred to with numeral  18 , comprising a shaft  20  connected to the support body  12 . The shaft  20  turns around a second axis, either orthogonal, or essentially orthogonal, to the pivoting axis  16  of the brake control lever  14 . The shaft  20  carries a pulley  24  on which an end portion of a control cable  25  of a front or rear derailleur of a bicycle is wound. The rotation of the shaft  20  in a first direction, indicated by arrow  26  in FIGS. 2 a ,  3   a  and  4   a  additionally winds the derailleur control cable on the pulley  24 , while a rotation of the shaft  20  in a second direction, indicated by the arrows  28  in the FIGS. 2 b ,  3   b  and  4   b,  releases the control cable of the derailleur. 
     For correct understanding of this invention, it is important to observe that the shaft  20  is constantly subjected to torque, which tends to turn it in the release direction of the derailleur control cable (in the direction indicated by the arrows  28 ). In the form of embodiment illustrated in the drawings, the torque which tends to turn the shaft  20  in the release direction of the cable is produced by the derailleur control cable, which is subjected to the action of an elastic element arranged in the derailleur. 
     With reference to FIG. 1, the gear change unit  18  comprises a gear change lever  30  arranged immediately behind the control lever of the brake  14 . The gear change lever  30  is associated to a mechanism for controlling the rotation of the shaft  20  in said first direction  26 . This mechanism can be made as described in detail in document EP 0 540 118, or alternatively as described in a contemporaneous patent application by the same Applicant with the same title. 
     With reference to the FIGS. from  2  to  5 , the unit  10  comprises a button lever  32 , associated to a mechanism for controlling the rotation of a shaft  20  in said second direction  28 . With reference to FIGS. from  2  to  5 , the button lever  32  is arranged on a side of the support body and is pivotally mounted on the support body by means of a pivot  34 , which axis is either parallel, or substantially parallel, to the rotation axis  22  of the shaft  20 . The gear  36  is solidly fastened to the shaft  20 . The gear  36  is equipped with a first set of teeth  38  and a second set of teeth  40 . The gear change control unit  18  comprises a rocker arm  42  pivoting on the support body  12  by means of pivot  44 . The rocker arm  42  comprises a first meshing unit  46 , which meshes the teeth of the first set, and a second meshing unit  48 , which meshes the teeth of the second set. The rocker arm  42  is made so that when the first meshing unit  46  meshes the teeth  38 , the second meshing unit  48  is released from the teeth  40  and, conversely, when the second meshing unit  48  engages the teeth  40 , the first meshing unit  46  is released from the teeth  38 . 
     The rocker arm  42  has an appendix  50 , which co-operates by resting on a corresponding appendix  52  of the button lever  32 , so that an anticlockwise oscillation of the lever  32  around the pivot  34  generates a clockwise oscillation of the rocker arm  42  around the pivot  44 . The rocker arm  42  and the button lever  32  co-operate with the respective elastic elements  54 ,  56 , consisting of, for example, small compressed coil springs, arranged between the support body  12  and the respective housings formed in the rocker arm  42  and in the button lever  32 . The spring  54  associated with the rocker arm  42  will tend to make the rocker arm  42  turn anticlockwise and, consequently, tend to keep the rocker arm  42  in a position in which the first meshing unit  46  meshes the teeth  38 . The spring  56  associated with the button lever  32  tends to turn the button lever  32  in the clockwise direction, that is in the direction corresponding to a respective distancing between the appendixes  52  and  50 . The spring  56  pushes the button lever  36  towards an end of stroke stop defined by a part of the support body  12 . 
     The teeth  38  and the corresponding meshing unit  46  are shaped so that when the first meshing unit  46  meshes the teeth  38  of the first set (FIGS. 2 a  and  2   b ), the gear  36  (and, consequently, the shaft  20 ) is free to turn in the direction shown by the arrow  26  in FIG. 2 (direction of most winding of the derailleur control cable on the pulley  24 ), while the meshing unit  46  prevents the rotation of the gear  36  in the opposite direction (release direction of the cable), indicated by the arrows  28  in the FIGS. 3 b  and  4   b.  When the second meshing unit  48  engages the teeth  40  of the second set (FIG. 3 b ) it prevents the rotation of the gear  36  in the direction indicated by the arrows  28  (release direction of the cable). 
     In the form of embodiment illustrated in the FIGS. from  1  to  5 , the teeth  38 ,  40  have saw-tooth profiles, which together form ratchet mechanisms with the corresponding meshing units  46 ,  48 , engaging in the direction  28  of cable release. 
     In the home condition, the unit is in the configuration shown in FIG. 2 a.  In this configuration, the derailleur control cable applies a torque to the shaft  20 , which tends to turn it anticlockwise. The ratchet mechanism formed by the the first meshing unit  46  and the teeth  38  prevents the rotation of the gear  36  and the shaft  20  in the anticlockwise direction. The sequence shown in FIGS. 2 a ,  3   a  and  4   a  illustrates the condition in which a single gear is shifted in the direction of increased winding of the derailleur control cable on the pulley  24 . The gear is shifted by oscillating the gear change lever indicated with numeral  30  in FIG.  1 . This oscillation of the lever controls the clockwise rotation of the shaft  20  with reference to FIGS. 2 a ,  3   a  and  4   a.  The ratchet mechanism formed by the first meshing unit  46  and the teeth  38  of the first set does not obstruct the clockwise rotation of the shaft  30 . This ratchet mechanism forms an indexing unit which signals the passage from one gear to the following gear by clicking. The user clearly hears when the mechanism shifts, because the first meshing unit  46  clips onto a subsequent tooth  38 . 
     The operative sequence shown in FIGS. 2 b ,  3   b  and  4   b  illustrates the condition in which the gear is shifted by operating the button lever  32 . The configuration in FIG. 2 b  shows a home position, which is identical to the position of FIG. 4 a.  Starting from the configuration in FIG. 2 b , the user presses the button lever  32  downwards and controls the oscillation around the pivot  44  of the rocker arm  42 . As soon as the first meshing unit  46  is released from the tooth  30 , the gear  36  is simultaneously free to turn under the action of the return torque generated by the derailleur control cable. The gear  36  consequently oscillates in the direction indicated by the arrow  28  until one of the teeth  40  meets the second meshing unit  48  (FIG. 3 b ). At this point, the shaft  20  has made a turn, which amplitude is equal to half the rotation needed to shift the gear. When the user releases the button lever  32 , the rocker arm  42  oscillates anticlockwise to return to home conditions. By effect of this oscillation, the second meshing unit  48  is released from the tooth, simultaneously releasing the gear  36 , which is free to turn anticlockwise under the action of the return torque generated by the derailleur control cable. The oscillation of the gear  36  ends when one of the teeth engages a first meshing unit  46  (FIG. 4 b ). Consequently, a gear shift control in the release direction of the derailleur control cable requires a downwards thrust of the button lever  32  and a release for the same lever which returns to home position under the return action of the elastic means  56 . A first half of the angular oscillation stroke of the shaft needed to shift the gear is made by effect of the downwards thrust of the button lever and the subsequent half of the angular stroke of the shaft is obtained by releasing the button lever. 
     This description shows that the amplitude of the angular stroke of the button lever  32  is independent with respect to the amplitude of the angular stroke of the shaft required to shift the gear. Advantageously, the button lever  32  can provide a very small angular stroke, so that the user can operate the lever with a light pressure of the thumb, without needing to make a long control stroke with the thumb. FIGS. from  6  to  9  illustrate an alternative form of embodiment of the mechanism described above. The parts corresponding to those described above are indicated with the same numeric references. 
     With respect to the form of embodiment described above, the variant in FIGS. from  6  to  9 , the gear  36  is equipped with front teeth, instead of radial teeth. The frontal teeth of the gear  36  are indicated with numerals  38  and  40 . The rocker arm  42  is ring-shaped and equipped with a pair of diagonally opposite appendixes  58 ,  60  (FIGS.  8  and  9 ), which define an orthogonal rotation axis with respect to the shaft  20 . The appendix  60  has a control arm  62  on which a portion of the button lever  32  (FIGS. 6 and 7) operates to control the oscillation of the rocker arm  42 . As shown in FIGS. 6 and 7, the spring  54  which holds the rocker arm  42  in home position acts along a direction of the axis  22  of the shaft  20 . The same spring  54  also holds the button lever  32  in home position. FIG. 6 illustrates the home position of the mechanism, while the FIG. 7 illustrates the position assumed by the mechanism following a downwards push of the button lever  32 . Similarly to the form of embodiment described above, the rocker arm  42  has a first and a second meshing unit  46 ,  48  for meshing the respective teeth  38 ,  40 . The meshing units  46 ,  48  are formed so to allow the free rotation of the gear in one direction and to prevent rotation in the opposite direction, as described above. The operation of the mechanism illustrated in FIGS. from  6  to  9  is substantially identical to that of the unit described above, with the only difference that the ratchet mechanism consists of teeth and meshing units which mesh frontally, instead of radially.