Abstract:
A transmission for a bicycle pedal has a fixed axle with an end operatively connected to a wheel of the bicycle and a guide axle connected to the fixed axle to form a crank. A bicycle pedal is rotatably mounted on a slider which is movably mounted on a guide portion of the guide rod for translation therealong. The ration of gyration of the pedal can be varied by sliding the pedal along the guide axle and/or telescoping the guide axle relative to the fixed axle. The slider and mounted pedal can be rotated toward the bicycle frame for compact storage.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to a bicycle pedal gearshift for enabling a change in speed change of a bicycle by adjusting the ratio of gyration of a pedal. 
   The driving gear of a bicycle generally includes a front wheel, a pedal connected to the wheel, a rear wheel and a chain connecting the two wheels. 
   The bicycle may be equipped with various gearshifts. The torque and speed of revolution to turn the pedals, and the rotational speed of the front and rear wheels may be adjusted to be suitable for a user by adjusting the gearshift. 
   Existing gearshifts may be classified into two types regardless of their various structures. 
   Some prior art gearshifts have a gear installed on the axle of the rear wheel of a bicycle, a gear cable connecting a chain to the gearshift and an operating mechanism installed on the handle of the bicycle to operate the gear cable. 
   There is another type gearshift enabling the adjustment of the ratio of gyration of a pedal through the installation of means of adjusting the length of a crank of the bicycle, and various means of adjusting the length are currently suggested. 
   Existing bicycle pedal gearshifts consist of numerous parts so that their configurations are complicated, causing them to frequently malfunction. The work involved in changing speed is difficult and such designs are not practically applied to and used for a bicycle. 
   SUMMARY OF THE INVENTION 
   An object of the invention to overcome the previously stated problems by providing a bicycle pedal gearshift for enabling the ratio of gyration of a pedal to be changed during its operation; 
   Another object of the invention is to enable a pedal to be folded in a line with a crank. 
   The above objects are accomplished by the bicycle pedal gearshift of the invention which has a fixed axle with one end connected to the wheel of bicycle and another end connect to a guide axle having a lower section in the form of a column with a square cross section and an upper section provided with a centrally threaded portion, and an upper section connected to the other end of the fixed axle. A crank includes the fixed axle and guide axle and a connector for attaching and supporting the fixed axle and guide axle. This bicycle pedal gearshift has a nut adapted to be threaded along the centrally threaded portion on the guide axle. A limit bolt is fixedly connected to the lower portion of guide axle. A slider having a central square bore is adapted to be translated along the lower guide section. A semicircular cut is formed on the lower portion of the slide for receiving the head of the limit bolt for stable support. Mounted on the slider are a pedal axle on which there is mounted a pedal, a ball for selectively being received in an upper supporting hole and a lower supporting hole in the guide axle when the slider is translated therealong, and a spring for urging the ball toward the supporting holes. 
   The bicycle pedal gearshift fixed axle has a cylindrical opening at its lower end for receiving the cylindrical upper section of the guide axle, the central threaded section and lower square section extending therebelow. 
   The bicycle pedal gearshift guide axle is formed with a plurality of vertically arranged holes. The fixed axle has a hole which can selectively be brought into registration with any one of the guide axle vertically arranged holes. A screw is inserted through the fixed axle hole and a selected one of the guide axle vertically arranged holes for fixing the fixed axle relative to the guide axle. 
   The bicycle pedal gearshift can alternatively have a fixed axle with a rectangular bore for receiving a guide axle having an upper section with a rectangular cross section, the guide axle having a central male screw section with a diameter smaller than width and depth of its upper section. 
   Accordingly, when the pedal is lifted by a foot in a vertical direction, or pulled in a horizontal direction, i.e., with the crank disposed vertically or horizontally, the slider is translated along the guide section of the guide axle and the ball is disengaged from the lower supporting hole and the slider can move to a position where it engages the nut where the ball can be received in the upper hole, and the translated slider on which the pedal is mounted is supported accordingly. This it can be seen that it is easy to adjust the ratio of gyration of the pedal quickly, and it is easy to change speed. Also, the length of crank can be adjusted by the above described connecting arrangement between the fixed axle and guide axle. Moreover, the range of speed change and utilization of space may be optimized by the allowable folding of the pedal inline with the crank upon storage of and moving of the bicycle. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view showing the bicycle pedal gearshift in accordance with a first embodiment of the invention; 
       FIG. 2  is a perspective view the bicycle pedal gearshift of  FIG. 1 , assembled; 
       FIG. 3  is the sectional view taken through line A–A′ of  FIG. 2 ; 
       FIG. 4  is a sectional view taken through line B–B′ of  FIG. 2 ; 
       FIGS. 5 &amp; 6  are perspective views showing the invention of  FIG. 1  with different ratios of gyration of a pedal; 
       FIGS. 7 and 8  are the sectional views taken through line C–C′ of  FIG. 3  showing the invention of  FIG. 1  with different lengths of the crank; 
       FIGS. 9–11  are the sectional views showing dispositions of the pedal as it is folded to a position inline with the crank; 
       FIG. 12  is a partially magnified sectional view showing a first alternative embodiment of a portion of the invention; 
       FIG. 13  is an exploded perspective view showing the bicycle pedal gearshift in accordance with a another embodiment of the invention; 
       FIG. 14  is a perspective view the bicycle pedal gearshift of  FIG. 13 , assembled; 
       FIG. 15  is a sectional view taken through line DD of  FIG. 14 ; 
       FIG. 16  is the partially magnified sectional view showing a portion of still another embodiment of the invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings, a bicycle pedal gearshift according the invention is equipped with a fixed axle  11 ,  41 ,  52  having one end adapted to be connected to the wheel of bicycle, and a guide axle  17 ,  58  with a lower section in the form of a column having a square cross section, an upper connection section  21 ,  60  adapted to be connected to the other end of the fixed axle  11 ,  41 ,  52 , and a central section having a male screw section  23 ,  62 . A crank  10 ,  40 ,  51  includes a connector arrangement for being installed between the fixed axle  11 ,  41 ,  52  and guide axle  16 ,  43 ,  57  to fix and support the fixed axle  11 ,  41 ,  52  and guide axle  16 ,  43 ,  57 . The bicycle pedal gearshift has a nut  27  adapted to be threaded along the male screw section  23 , 62  on the guide axle  16 , 43 , 57 . A limit bolt  29  can be fixed and connected to the lower portion of guide axle  16 , 43 , 57 . A slider  30  has a square bore  31  formed in its center for being translated along the guide section  17 , 58  on the guide axle  16 , 43 , 57 . A blind hole  32  is formed inside the bore on one side of the slider  30 , on the bottom of which there is also formed a semicircular limit groove  33  for receiving the head of the limit bolt  29  so that it can be stably supported. The slider  30 , 65  is equipped with a pedal axle allowing the pedal  35 , 69  to be connected to the side of the slider opposite the side on which the ball  37  is mounted. The ball  37  can be selectively received in an upper supporting hole  19  and a lower supporting hole  20  on the side of the guide axle  16 , 43 , 57  as the slider  30 , 65  is translated under pressure from a spring  36  inserted in the blind hole  32  in the slider  30 , 65 . 
   When the pedal  35 ,  69  is lifted by a foot in a vertical direction, or pulled in a horizontal direction, positioning the crank  10 ,  40 ,  51  vertically or horizontally, the slider  30 ,  65  is translated along the guide section  17 ,  58  of guide axle  16 ,  43 ,  57  and the ball  37  is released from the bottom supporting hole  20 . As the slider  30 ,  65  moves toward nut  27  during the continual rotation of the pedal  35 ,  69 , the ball  37  is received in the upper supporting hole  19  and the translated pedal  35 ,  69  is supported there. Hence, easy adjustment of the ratio of gyration of the pedal is enabled and quick and easy speed change is allowed. Also, adjusting the length of crank  10 ,  40 ,  51  by the above described connector arrangement is possible, and the range of speed change and utilization of space may be optimized by the allowable folding of the pedal with the crank inline upon storage of and moving the bicycle. 
   The detailed characteristics and advantages of the invention will be made more clear by the following descriptions referring to the drawings. 
   Referring to  FIG. 1 , the bicycle pedal gearshift of the invention is includes the crank  10 , the slider slider  30  and the pedal which is mounted via an axle on the slider  30 . 
   The crank  10  includes the fixed and guide axles  11  and  16 , and the connector arrangement for connecting these two axles as shown in  FIGS. 1 ,  2  and  3 . 
   The fixed axle  11  has a mounting hole  12  at its upper end and an internal bore  13  inside its lower end, and a hole  14  for receiving a fixing screw  25  for purposes which will be explained later. 
   The guide axle  16  on which the guide section  17  having a column equipped with a square cross section is inserted into the square hole  31  of the slider  30  and moved relative to the slider, and the cylindrical upper connection section  21  is formed on the upper portion of guide axle  16  and the center of guide axle  16  has a threaded section. 
   The hole  18  formed at the lower end of guide section  17  of guide axle  16  receives limit bolt  29 . A number of fixed holes  22  are vertically arranged along connection section  21 . 
   The screw  25  is adapted to connect the fixed axle  11  and guide axle  16 . More specifically, the set screw  25  is threaded through the hole  14  in axle  11  and passed into a selected one of the holes  22  of guide axle  16 . 
   Therefore, the connection devices for crank  10  include the connection hole  14  of the fixed axle  11 , the fixed section  21  of guide axle  16  and the set screw  25  which is adapted to be connected to the above two components. 
   The nut  27  which is to be mounted on the guide axle  16  of crank  10  is threaded onto the male screw section  23  of guide axle  16  and limits the translation range of the slider  30  as will be explained, and the previously mentioned male screw section of limit bolt  29  is received in the fixed hole  18  of guide axle  16 , so that the limit groove  33  of slider  30  can be engaged by the head of limit bolt  29 . 
   The slider  30  is mounted on the guide section of guide axle  16 , and the square hole  31  is formed to allow the slider to be translated along the guide section. There is a blind hole  32  formed inside of the slider in which the spring  36  and the ball  37  are to be inserted in turn. 
   Therefore, when the slider  30  is inserted into the guide section  17  of guide axle  16  and translated, the ball  37  will be selectively captured either within the upper supporting hole  19  or lower supporting hole  20  of guide axle  16 . 
   The semi-circular groove  33  of is formed on one side of the slider  30  for being stably supported on the head of limit bolt  29  at the lower limit of travel of slider  30 , and the pedal axle  34  is fixed to the other side of slider  30  for receiving pedal  35 . 
   As previously stated, the slider  30  of the bicycle pedal gearshift of the invention is mounted on the guide section  17  of guide axle  16 , and the nut  27  is connected to the male screw section  23  of guide axle  16 , and the upper end of fixed axle  11  of crank  10  is connected to the chain wheel of the bicycle after the fixed axle  11  is connected to the connection section  21  of guide axle  16 . In this configuration, the gearshift of the invention is installed on the bicycle. 
   This bicycle pedal gearshift of the invention is normally operated similarly to one on a common bicycle as shown in FIGS.  2  and  3 ., upon, The pedal  35  is escalated by lifting the toe with the crank positioned vertically, whereby the pedal is pulled up to the horizontal direction with the crank positioned horizontally. 
   The guide section  17  of guide axle  16  is in the form of a rectangular parallelepiped, and the perimeter of square hole  31  of slider  30  contacts the four sides of guide section  17 , whereby the slider  30  can be translated along the guide section  17  when the guide section  17  is has a horizontal direction, but if the slider  30  is not in a horizontal position, the slider  30 , and the pedal mounted on the slider are not translated. 
   For example, when the pedal  35  is lifted by the toe while the crank  10  is positioned vertically, or the pedal  35  is pulled in a horizontal direction wile the crank  10  is positioned horizontally, the direction of lifting or pulling the pedal  35  corresponds to the position of the crank  10 , and the contacting resistance between the four sides of guide section  17  and four sides of the slider within square hole  31  is minimized, so the slider  30  is translated along the guide section  17  as shown on  FIG. 5 . 
   But, if the pedal  35  is lifted when the crank  10  is not vertically positioned, or the pedal  35  is pulled in a horizontal direction when the axle of crank  10  is not horizontally positioned, substantial friction occurs between the four sides of guide section  17  and the four sides within square hole  31 , whereby the slider  30  is not translated. 
   Therefore, the pedal  35  must be lifted while the crank is positioned vertically, or the pedal must be pulled in a horizontal direction while the crank is positioned horizontally in order to translate the pedal when the bicycle is under operation. In other words, only when the direction of crank  10  corresponds to the direction of force can the slider  30  be translated along the guide section  17 . 
   When revolving the crank  10  by providing force to the pedal  35  to move the bicycle forward, the slider  30  is not translated along the guide section  17  of guide axle  16 , as will be explained in more detail below. 
   When pedaling to move the bicycle forward, pedaling accelerates the bicycle when the crank  10  is within a range of more than 0° and less than 180° relative to the vertical. But when the crank is precisely positioned at 0° or 180° pedaling is difficult  35  and the bicycle is not accelerated, even during pedaling. 
   When pedaling while the crank  10  is within the range of between 90° and 135°, the bicycle is readily accelerated, so users normally pedal to accelerate the bicycle at this time, and the appropriate way of pedaling is from up to down, in other words, to pedal vertically. 
   Therefore, to move the bicycle forward by transmitting the force to the pedal, the direction of application of force to the pedal  35  must differ from the position of crank  10 , and the slider  30  is not translated along the guide section  17  of guide axle  16  by the force applied to revolve the crank  10 . 
   In accordance with the previously stated principles, the speed change process of the bicycle pedal gearshift of the invention will be described as follows: 
   To reduce the ratio of gyration of pedal  35  under the conditions shown in  FIGS. 2 and 3 , the pedal  35  is lifted while the crank  10  is vertical, or the pedal  35  is pulled while the crank  10  is horizontal, at which time the slider  30  is translated along the guide section  17  of guide axle  16 . 
   If the user keeps translating the pedal  35 , the ball  37  is captured in the upper supporting hole  19  of guide axle  16  and the slider  30  and guide axle  16  are fixed. The upper limit of slider  30  is determined by the nut  27  which, when engaged, prevents further translation of slider  30 . 
   Conversely, to increase the ratio of gyration of pedal  35 , the pedal  35  is pressed downwardly after balancing the crank  10  vertically, or the pedal  35  is pushed in a horizontal direction after balancing the crank  10  horizontally, and the slider  30  is translated along the guide section  17  until the limit groove  33  of slider  30  is supported on the head of limit bolt  29  and translation is limited upon the ball&#39;s being captured in lower supporting hole  20 . 
   As previously stated, the user may adjust the height of pedal  35  to be suitable for accelerating the speed of the bicycle according to the user&#39;s height by simply adjusting the ratio of gyration of pedal  35 . 
   The bicycle pedal gearshift of the invention allows the user to adjust the ratio of gyration of pedal  35  by using the combined structure between the guide section  17  of guide axle  16  and slider  30 , and the connection between the fixed axle  11  and guide axle  16 . 
   In another words, the ratio of gyration of pedal  35  can be increased from the disposition shown in  FIG. 7  to the disposition shown in  FIG. 8  by releasing the set screw  25  and lowering the guide axle  16  relative to the fixed axle  11  after which the guide axle  16  is fixed relative to the fixed axle  11  by combining rotation of set screw  25  fully into a corresponding hole  22  as shown on  FIG. 8 . 
   Therefore, the bicycle pedal gearshift of the invention enables the user to adjust the ratio of gyration of pedal  35  by using the combined structure between the guide section  17  of guide axle  16  and slider  30 , and the connection between the fixed axle  11  and guide axle  16 . 
     FIGS. 9 and 11  show other advantages of the bicycle pedal gearshift of the invention. When the slider  30  is translated to the perimeter of threaded section  23 , the slider  30  leaves the guide section  17  and can freely revolve clockwise and counterclockwise as shown on  FIG. 9 . Under this condition, the pedal  35  can be brought even closer to the bicycle body by rotating the pedal  35  about its axis to a plane parallel to the axle of crank  10  as shown on  FIG. 10  and revolving the slider  30  90 degrees as shown on  FIG. 11 . 
   This it is seen that reducing the entire width of the bicycle is possible whereby the user may insert and store the bicycle in the relatively narrow space such as the trunk of a car. 
   The bicycle pedal gearshift of the invention has many advantages as follows: 
   First, speed change is available by adjusting the size of the orbit of the pedal  35  through the adjustment of the ratio of gyration of the pedal  35 . 
   Second, adjusting the height of pedal  35  to be suitable for people of different height is possible, whereby the invention allows users to ride a bicycle under optimized conditions thereby reducing the likelihood of an accident. 
   Third, even the user who have legs of different lengths due to physical handicap may conveniently use the bicycle as it is possible to adjust the height of only a pedal. 
   Fourth, easy adjustment of the ratio of gyration of a pedal  35  is possible even during a ride. When lifting the pedal  35 , using the toe, with the crank  10  positioned vertically, or pulling the pedal  35  to a horizontal position with the crank  10  disposed horizontally, the ratio of gyration of pedal  35  is easily reduced, and as previously stated, if pressing or pushing the pedal  35 , the ratio of gyration of pedal  35  is easily increased, so the user may simply adjust the ratio of gyration of the pedal  35  even during a ride. 
   Fifth, the user may adjust the ratio of gyration of the pedal  35  in diverse ways. The user may adjust and firmly fix the height of pedal by using the adjustable connection between the fixed axle  11  and connection section  21  of guide axle  16 . Also, easy and quick adjustment of the height of pedal  35  is possible during a ride by using the combined structure between the slider  30  and guide section  17  of guide axle  16 . 
   Therefore, the bicycle pedal gearshift of the invention may be made suitable for the needs of users by adjusting the ratio of gyration of pedal  35  depending on who the user is, number of users, and frequency of adjusting the ratio of gyration of pedal  35 . 
   Sixth, the number of components of the gearshift is small and the configuration of the gearshift is simple. Parts of the bicycle pedal gearshift of the invention such as nut  27 , set screw  25 , limit bolt  29 , ball  37  and spring  36 , other than the fixed axle  11 , guide axle  16 , and slider  30  are easy to purchase, and production and assembling of parts is relatively simple, whereby the production cost may be reduced. 
   Seventh, upon storing the bicycle in a narrow space such as the trunk of a car, storage of existing bicycles is difficult or sometimes impossible, but according to the instant invention, the pedal  35  may be moved closer to the bicycle body, so the entire width of the bicycle is minimized and the user may insert and store the bicycle in a relatively narrow space such as the trunk of car. 
     FIG. 12  is a partially magnified sectional view showing an example of using the bicycle pedal gearshift of the invention in another way. 
   The connective device of this bicycle pedal gearshift includes a fixed axle formed with a plurality of supporting holes  42  arranged vertically, a guide axle  43  in which there is formed a spring channel  44  for corresponding to a selected one of the supporting holes  42 , a spring disposed within the spring channel  44 , and a ball for being captured within the selected one of the supporting holes. 
   Therefore, the user may adjust the length of crank  40  by lowering or elevating the guide axle  43  after inserting the ball for crank  46  which ball is pressed by a tool such as pressing pin  47  into the spring slot, and the effect is the same as the one of the connecting devices shown in  FIGS. 1 and 11 . 
     FIGS. 13–15  are an exploded perspective view, combined sectional view, and sectional view taken through line d—d, respectively, showing another operative example of the bicycle pedal gearshift of the invention. There is shown a crank  51 , slider  65  and a pedal  69  adapted to be connected to a side of the slider  65  via a hinge. The crank  51  includes a fixed axle  52 , guide axle  57 , and the connector for combing these two axles as shown in  FIGS. 13–15 . 
   In the fixed axle  52 , connecting holes  53  are formed on the upper portion and connecting hole  54  is formed on the lower portion. A rectangular bore  55  is formed in the center of this axle. 
   The guide axle  57  is has a guide section  58  formed with a hollow bore  59  on a lower portion, a rectangular connection section  60  adapted to be received in the rectangular bore  55  on the fixed axle  52  on an upper portion, and a threaded section  62  having a diameter smaller than the width and depth of the central portion. Formed on the connection section  60  are a plurality of grooves  61  for receiving a set screw  70  after being threaded into a connection hole  54 . 
   Here, the connection device refers to the connection hole  54  on the fixed axle  52 , the grooves  61  on the guide axle  57 . and fixing screw  70   
   In the bicycle pedal gearshift of the invention in accordance with this embodiment, slider object  65  is mounted on guide section  58  on guide axle  57 , connection section  61  on guide axle  57  is received within the rectangular bore in the fixed axle  52  and fixing screw  70 , is threaded through connection hole  54  on fixed axle  52  and received in one of the grooves  61 . 
   The bicycle pedal gearshift of this embodiment of the invention has the following advantages: 
   First, the rectangular bore  55  in the axle  52  is penetrated by a rectangular parallelopiped so the guide axle cannot be moved right and left relative to the fixed axle and the connection is snug. 
   Second, the rectangular bore penetrates the fixed axle  52 , whereby under the condition of the fixed axle  52  and guide axle  57  shown in  FIG. 3 , the end portion of connection section  60  on the guide axle  57  can be withdrawn relative to connection hole  54 , thereby enabling the length of crank  51  to be minimized and enabling diversifying the range of speed change of the bicycle. 
   Third, the hollow section  59  formed in the guide section  58  on the guide axle  57  reduces the weight of guide axle  57  thereby making lifting moving the bicycle easier. In manufacturing of the guide axle  57 , materials are saved and manufacturing cost is reduced. 
     FIG. 16  shows another operative example of a connection device for the bicycle pedal gearshift of the invention in a partially enlarged sectional view. The bicycle pedal gearshift has a fixed axle  74  formed with a plurality of supporting holes aligned in one side, and guide axle  72 , in which there is formed a rectangular spring bore  73  in one side near an upper end, for being selectively aligned with one of the supporting holes  75 . A spring for crank  76  is received within spring bore  73 . A pin  77  of square cross section is partially inserted into the spring bore  73  for being urged into one of the holes  75 . The supporting holes  75  and spring bore  73  in which the connecting pin  77  is connected have corresponding images, so the guide axle  72  and fixed axle  74  are more firmly connected and supported as compared with the crank ball  46 . 
   As previously stated, the bicycle pedal gearshift of the invention can optimize the utilization of space. When lifting the pedal to the vertical position or pulling the pedal to the horizontal position with the foot, with the crank  10 ,  40 ,  51  balanced vertically or horizontally, the slider is translated along the guide section of the guide axle and the ball leaves the bottom supporting hole. When the slider is in engagement with the nut, the ball is supported by the upper supporting hole and the translated pedal is supported accordingly, so easy adjustment of the ratio of gyration of the pedal is possible and quick and easy speed change is allowed and also, adjusting the length of the crank by the connecting device is possible, and the range of speed change and utilization of space may be optimized by the allowable folding of the pedal with the crank inline upon storage of and moving the bicycle.