Abstract:
An apparatus for controlling a movable bicycle device comprises a power supply sensor that detects an abnormal power supply characteristic, and a control unit operatively coupled to the power supply sensor. The control unit provides a first signal to command the bicycle device to move in a first manner when the power supply has a first characteristic, and the control unit provides a second signal to command the bicycle device to move in a different second manner when the power supply has a second characteristic.

Description:
BACKGROUND OF THE INVENTION 
   The present invention is directed to bicycles and, more particularly, to a method and apparatus for controlling the operation of a bicycle transmission to compensate for power supply characteristics. 
   Bicycle transmissions that are operated by an electric motor or the like have recently become known. Such transmissions may be shifted automatically according to the bicycle speed or shifted manually by the rider. Typically, a shift command is generated according to the bicycle speed or manual input by the rider, the motor is controlled by a transmission operating unit in response to the shift command, and the gear ratio of the transmission is set accordingly. 
   For example, U.S. Pat. No. 6,162,140 discloses a motor driven derailleur that includes a base member, a movable member, and a linkage mechanism. The linkage mechanism includes a link member coupled to the base member and to the movable member so that the movable member moves relative to the base member. The link member is pivotally coupled to one of the base member and the movable member through a link coupling member, and a motor is provided for rotating the link-coupling member. The movable member moves relative to the base member in response to rotation of the link-coupling member. 
   U.S. Pat. No. 5,357,177 discloses an electrical adjustment device for an electrical chain transfer device for bicycles. The adjustment device comprises an adjusting element, a drive device for moving the adjusting element, and a control unit for controlling the drive device. A presetting device is operatively coupled to the control unit for storing a plurality of set values, wherein each set value corresponds to an operational position of the adjusting element and therefore the chain transfer device. The adjusting element can be moved to a desired set position, and then the set position value can be stored in the presetting device to replace a former set position value and thereby establish or fine tune an operating position of the chain transfer device. 
   U.S. Pat. No. 6,740,003 discloses an apparatus for moving an electrically controlled bicycle derailleur from a first sprocket to a second sprocket. The apparatus comprises a derailleur position input for receiving a signal from a potentiometer mounted to the derailleur that indicates a position of the derailleur, a memory for storing a reference derailleur position for the second sprocket, and a motion control circuit that provides a plurality of signals to move the derailleur from the first sprocket to the second sprocket. The plurality of signals comprises a first signal generated when the derailleur initially moves away from the first sprocket and a second signal generated when the derailleur is in close proximity to the second sprocket. The second signal prevents the derailleur from overshooting the second sprocket. 
   In such known systems, the speed of the motor that operates the various positioning elements depends on various characteristics of the power supply, such as voltage. For example, if the power supply voltage is higher than the designed operating voltage for the motor, possibly caused by high ambient temperature or high charging voltage from a wheel generator, then the motor shaft used to operate a derailleur may rotate faster than expected. If the sampling rate for the position sensor is not sufficiently high, then the derailleur may overshoot the destination sprocket and may even cause the chain to engage the sprocket beyond the destination sprocket. Thus, properly controlling the motor can become very difficult, including attempts to move the derailleur back to the proper position. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to various features of an apparatus for controlling a movable bicycle device. In one embodiment, an apparatus for controlling a movable bicycle device comprises a power supply sensor that detects an abnormal power supply characteristic, and a control unit operatively coupled to the power supply sensor. The control unit provides a first signal to command the bicycle device to move in a first manner when the power supply has a first characteristic, and the control unit provides a second signal to command the bicycle device to move in a different second manner when the power supply has a second characteristic. 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 a side view of a bicycle that includes a particular embodiment of an electrically controlled bicycle transmission; 
       FIG. 2  is a detailed view of particular embodiments of handlebar mounted components of the bicycle shown in  FIG. 1 ; 
       FIG. 3  is a block diagram of a particular embodiment of an overall transmission control unit; 
       FIG. 4  is a flow chart of a particular embodiment of an algorithm used to control the bicycle transmission; and 
       FIG. 5  is a block diagram of another embodiment of an overall transmission control unit. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
     FIG. 1  is a side view of a bicycle  1  that includes a particular embodiment of an electrically controlled bicycle transmission. In this embodiment, bicycle  1  is a sport mountain bicycle, and it comprises a frame  2 , a front fork  3  rotatably mounted to frame  2 , a handlebar  4  mounted to the upper part of fork  3 , a front wheel  5  rotatably attached to the lower part of fork  3 , a rear wheel  6  rotatably attached to the rear of frame  2 , a chain  7 , a front transmission  8 , a rear transmission  9 , and a saddle  11 . A front wheel brake  16  is provided for braking front wheel  5 , and a rear wheel brake  17  is provided for braking rear wheel  6 . As shown in  FIG. 2 , respective grips  12   a ,  12   b  and brake levers  13   a ,  13   b  are provided on both ends of handlebar  4 . Brake lever  13   b  is connected to front wheel brake  16  for braking front wheel  5 , and brake lever  13   a  is connected to rear wheel brake  17  for braking rear wheel  6 . 
   Front transmission  8  is a mechanical unit attached in the central lower part of frame  2  for transmitting the drive force generated by the rider to rear transmission  9  via chain  7 . Front transmission  8  comprises three sprockets  37  of various sizes and a front derailleur  33 . The three sprockets  37  are installed on a gear crank  31  that is rotated when the rider pushes pedals  32   a  and  32   b . Gear crank  31  comprises a crankshaft  34  that passes horizontally and rotatably through the central lower part of frame  2 , a right crank  35 , and a left crank  36 . One end of the right crank  35  is connected to the right side of crankshaft  34 , and the three sprockets  37  are attached to right crank  35 . One end of the left crank  36  is connected to the left side of crankshaft  34 . The other ends of right crank  35  and left crank  36  rotatably support pedals  32   a  and  32   b , respectively. Front derailleur  33  engages chain  7  with one of the three sprockets  37  and is moved by an integrated front derailleur motor unit  50  ( FIG. 3 ) that is controlled by a transmission control unit  15  mounted to handlebar  4 . An integrated front derailleur position sensor  52  detects the position of front derailleur  33 , and hence the current sprocket  37  engaged by chain  7 . 
   Rear transmission  9  serves to transmit the driving force transmitted by chain  7  to rear wheel  6 . Rear transmission  9  comprises a rear sprocket cluster  41  and a rear derailleur  42 . In this embodiment, rear sprocket cluster  41  comprises seven sprockets  43  of different sizes that are mounted concentrically with the hub portion of rear wheel  6 . Rear derailleur  42  engages chain  7  with one of the seven sprockets  43  and is moved by an integrated rear derailleur motor unit  54  ( FIG. 3 ) that is controlled by transmission control unit  15 . An integrated rear derailleur position sensor  56  detects the position of rear derailleur  42 , and hence the current sprocket  43  engaged by chain  7 . 
   As shown in  FIG. 2 , shift command units  14   a ,  14   b  are provided inwardly of grips  12   a ,  12   b  and brake levers  13   a ,  13   b , respectively. Transmission control unit  15  is attached to the central portion of handlebar  4 , and it is connected to shift command units  14   a ,  14   b . Shift command units  14   a ,  14   b  are used for manually shifting front transmission  8  and rear transmission  9 . A rear upshift button  18   a  and a rear downshift button  19   a  are provided in shift command unit  14   a , and a front upshift button  18   b  and a front downshift button  19   b  are provided in shift command unit  14   b . In this embodiment, upshift buttons  18   a  and  18   b  provide signals for upshifting front transmission  8  and rear transmission  9  by one sprocket. Similarly, downshift buttons  19   a  and  19   b  provide signals for downshifting front transmission  8  and rear transmission  9  by one sprocket. 
   As shown in  FIGS. 1 and 3 , transmission control unit  15  is connected to front transmission  8  and to rear transmission  9  through a drive unit  28 . As shown in  FIG. 3 , drive unit  28  houses a power supply  60  and a power supply sensor  64 . Power supply  60  provides operating power to front derailleur motor unit  50 , rear derailleur motor unit  54  and/or transmission control unit  15 ; and power supply sensor  64  senses a characteristic of power supply  60 . In this embodiment, power supply sensor  64  comprises a voltage sensor that senses a voltage of power supply  60 . 
   Transmission control unit  15  comprises a control unit  23  having a CPU  21  and a memory  22 , a display unit  24  for displaying travel information, a power switch  25 , and a mode switch  26  that changes an operating mode of transmission control unit  15 . CPU  21  is primarily responsible for controlling front transmission  8  and rear transmission  9  in response to signals provided by shift command units  14   a  and  14   b , front derailleur position sensor  52 , rear derailleur position sensor  56 , power supply sensor  64 , and data stored in memory  22 . CPU  21  also controls the information presented on display unit  24 . As shown in  FIG. 2 , transmission control unit  15  includes a box-like housing  27 . Display unit  24 , power switch  25  and mode switch  26  are arranged on the upper surface of housing  27 . 
     FIG. 4  is a flow chart of a particular embodiment of an algorithm used to control either front transmission  8  or rear transmission  9  in a manner that compensates for a characteristic (e.g., voltage) of power supply  60 . The algorithm is invoked when the rider turns on the power switch  25  of transmission control unit  15 . 
   Initial setting of transmission control unit  15  is conducted in a Step S 1 . The initial setting typically includes resetting of flags and counters and other processing to prepare the system for proper operation. It is then determined in a Step S 2  whether or not a shift request has been received from one of shift command unit  14   a  or shift command unit  14   b . If not, then processing simply returns to step S 2 . Otherwise, a current voltage V P  of power supply  60  is acquired from power supply sensor  64  in a step S 3 . It is then determined in a step S 4  whether or not the voltage V P  is above a predetermined voltage V H  stored in memory  22 . In this embodiment, the voltage V H  is the normal operating voltage of the corresponding front derailleur motor  50  or rear derailleur motor  54 . A voltage greater than V H  indicates an abnormal power supply characteristic. If the power supply voltage V P  is not above the voltage V H , then a signal for the regular operation of front derailleur motor unit  50  or rear derailleur motor unit  54  is provided by control unit  23 . For example, if control unit  23  operates front derailleur motor unit  50  or rear derailleur motor unit  54  directly, then the signal output by control unit  23  may provide an analog voltage sufficient to operate motor unit  54  in a normal manner. If front derailleur motor unit  50  or rear derailleur motor unit  54  includes its own control processor, then the signal provided by control unit  23  may be a multibit digital signal as shown in Table 1. 
   
     
       
             
             
             
             
           
         
             
                 
               TABLE 1 
             
             
                 
                 
             
             
                 
               Function 
               Bit 1 
               Bit 2 
             
             
                 
                 
             
           
           
             
                 
               Rotate Clockwise 
               0 
               1 
             
             
                 
               Rotate Counterclockwise 
               1 
               0 
             
             
                 
               Brake 
               1 
               1 
             
             
                 
               Stay 
               0 
               0 
             
             
                 
                 
             
           
        
       
     
   
   On the other hand, if it is determined in step S 4  that the power supply voltage V P  is greater than the voltage V H , then an abnormal power supply characteristic has been detected, processing moves to step S 6 , and a modified operation of front derailleur motor unit  50  or rear derailleur motor unit  54  is performed. In this embodiment, front derailleur motor unit  50  or rear derailleur motor unit  54  is operated in an intermittent manner. For example, if control unit  23  operates front derailleur motor unit  50  or rear derailleur motor unit  54  directly, then the signal output by control unit  23  may provide an intermittent (e.g., pulsed or square wave) analog voltage sufficient to operate front derailleur motor unit  54  in a stepped manner. If front derailleur motor unit  50  or rear derailleur motor unit  54  includes its own control processor, then the signal provided by control unit  23  may be alternating multibit digital signals selected from Table 1. For example, control unit  23  may provide a clockwise rotation signal followed by a stay signal, then followed by a clockwise rotation signal, then followed by a stay signal, and so on. In either case, the derailleur will move a shorter distance for a given time interval when operating in Step S 6  than when operating in Step S 5 . This ensures that a slow sampling rate of front derailleur position sensor  52  or rear derailleur position sensor  56  (relative to the processing speed of control unit  23 ) will not allow the corresponding front derailleur motor unit  50  or rear derailleur motor unit  54  to move front derailleur  33  or rear derailleur  42  beyond the destination sprocket. 
   In any event, it is then determined in a Step S 7  whether or not the front derailleur position sensor  52  or rear derailleur position sensor  56  indicates that the corresponding front derailleur  33  or rear derailleur  42  has reached the desired destination sprocket. If so, then processing returns to Step S 2 . Otherwise, processing returns to Step S 3 . 
   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,  FIG. 5  is a block diagram of another embodiment of an overall transmission control unit that employs the concept of distributed processing. In this embodiment, a rear derailleur control unit  23   a  having a CPU  21   a  and a memory  22   a  is connected to rear upshift button  18   a  and rear downshift button  19   a  for controlling rear derailleur  42  using rear derailleur motor unit  54  and rear derailleur position sensor  56 . A separate front derailleur control unit  23   b  having a CPU  21   b  and a memory  22   b  is connected to front upshift button  18   b  and front downshift button  19   b  for controlling front derailleur  33  using front derailleur motor unit  50  and front derailleur position sensor  52 . The operation of rear derailleur control unit  23   a  and/or front derailleur control unit  23   b  may be the same as described for control unit  23 . This embodiment allows some changes of gear ratio even if one of the control units should malfunction. 
   Transmission control unit  15  may automatically control the operation of front transmission  8  and rear transmission  9  according to bicycle speed or some other parameter in a known manner instead of or in addition to the manual operation described. The teachings herein can be applied to any movable bicycle component. 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 or emphasis on a particular structure or feature.