Abstract:
The present invention relates to an adjustable drive mechanism that converts a force supplied from an operator or other means along an adjustable curve path into rotary motion. More particularly, the present invention relates to an adjustable drive mechanism configured for an operator driven or motor driven exercise apparatus such as a stationary bicycle, recumbent stationary bicycle, cross trainer or other devices such as a bicycle. The present invention relates to the kinematic motion control of pedals which follow more complex curves that can be changed with the adjustable drive. More particularly, an adjustable drive mechanism based upon a pair of crank linkages and belt assembly can be incorporated into several exercise apparatus to drive a load resistance.

Description:
This application is a continuation-in-part of U.S. patent application Ser. No. 10/303,938 filed Nov. 26, 2002, now U.S. Pat. No. 6,830,538. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field 
     The present invention relates to a drive mechanism that converts a force supplied from an operator or other means along an adjustable curve path into rotary motion. More particularly, the present invention relates to an adjustable drive mechanism configured for an operator driven or motor driven exercise apparatus such as a stationary bicycle, recumbent stationary bicycle, cross trainer or other devices. 
     2. State of the Art 
     The benefits of regular exercise to improve overall health, appearance and longevity are well documented in the literature. For exercise enthusiasts, the search continues for safe apparatus that provides exercise for maximum benefit in minimum time with less boredom. 
     Exercise bikes currently use simple cranks to guide the feet along a circular path while receiving operator force to rotate a flywheel. Several attempts have been made to guide the feet along an elliptical path while seated for exercise such as Eschenbach in U.S. Pat. No. 5,836,855 and Maresh in U.S. Pat. No. 5,938,570. Knudsen in U.S. Pat. No. 5,433,680 shows an elliptical path generating mechanism with pedals having only one pivot allowing the pedal to rotate unconstrained about the pivot as in a bicycle crank. Marchou in U.S. Pat. No. 2,088,332 shows a gear pair configured to receive force from a piston. Stiller et al. in U.S. Pat. No. 5,419,572 shows a pair of gear stacks used to guide foot pedals along an elliptical path for a bicycle. Ticer et al. in U.S. Pat. No. 5,261,294 shows an adjustable elliptical crank using gears applicable for exercise. 
     Recently, a new category of exercise equipment has appeared on the commercial market called elliptical cross trainers. These cross trainers guide the feet along a generally elliptical shaped curves to simulate the motions of jogging and climbing. Several commercial cross trainers are now offered with elliptical foot movement that can be changed when desired by an operator. 
     Rodgers in U.S. Pat. No. 5,743,834 shows an elliptical cross trainer having an adjustable crank where a motor attached to a moving crank arm can change crank length using gears and screw threads. Stearns et al. in U.S. Pat. No. 6,027,431 shows an elliptical cross trainer having an adjustable crank where gear pairs and a spiral slot operated by a stationary motor change the length of a crank arm. Other variations of an adjustable crank are shown in Stearns et al. in U.S. Pat. No. 6,338,698 and U.S. Pat. application No. 2002/0198084 A1 using various linkage and slotted discs. 
     There is a need for a drive mechanism to guide a pedal, foot support, connector link or handle along an adjustable curve that is easier to fabricate than the prior art. There is a further need for an adjustable drive mechanism that can be incorporated in an exercise apparatus or other device where the drive pivot such as a pedal follows an adjustable curve during operation of the exercise apparatus. There is a further need for a drive mechanism that changes radius on a periodic basis. 
     It is one objective of this invention to provide an adjustable drive that allows variable pedal movements. Another objective of this invention is to integrate the adjustable drive into several exercise apparatus. Yet another object of this invention is to provide an indirect application of the adjustable drive to adjust pedal path curves for exercise apparatus. 
     SUMMARY OF THE INVENTION 
     The present invention relates to the kinematic motion control of pedals which follow more complex curves that may be changed. More particularly, an adjustable drive mechanism based upon a linkage and belt assembly can be incorporated into several exercise apparatus to drive a flywheel. 
     In the preferred embodiment, a pair of crank linkage each having a drive pivot to receive operator force rotate about a pivot axis. Each crank linkage includes a crank arm, crank link, adjustment arm and an adjustment link. In this embodiment, the drive pivot is positioned at the end of the crank link. Movement of the adjustment arm relative to the crank arm cause the predetermined distance from each drive pivot to the pivot axis to change. Both adjustment arms and crank arms are configured to rotate about the pivot axis. The adjustment arms are connected generally opposed to an adjustment shaft. The crank arms are also positioned generally opposed but each is attached to a separate crankshaft positioned concentric to the adjustment shaft. 
     A belt assembly controls the relative angular position of each adjustment arm to each crank arm configured such that a change of position for a pair of timing belt pulleys will change the predetermined distance between the drive pivots and the pivot axis. A set of timing belt pulleys are attached to the adjustment shaft and crankshafts. A jackshaft contains similar pulleys positioned distal the pivot axis. 
     Timing belts engage the pulleys such that the adjustment shaft, crankshaft and jackshaft rotate at the same speed. Idler pulleys are positioned on brackets intermediate the pivot axis and jackshaft. A pair of movable pulleys are pivotally attached to a slider link that is configured to be movable in a direction generally perpendicular to a plane connecting the pivot axis to the jackshaft. One of the timing belts engage the movable pulleys, idler pulleys, adjustment shaft and jackshaft. Movement of the slider link during operation or while not moving changes the angular relationship between the adjustment arms and crank arms resulting in a change of the predetermined distance. While timing belts are used in the preferred embodiment, chains or other form of flexible linking may also be used. The position of the slider link can be determined manually using a handle and screw thread or an electrically controlled actuator from a remote location. 
     The adjustable drive has application in many exercise apparatus such as stationary or moving bicycles, recumbent cycles, tread climbers, steppers, cross trainers and hand operated devices. Further, application can extend to other apparatus outside the field of exercise that use a crank where a change of crank length can provide adjustment to the performance of the apparatus. The adjustable drive can be used to convert operator force into rotary motion or a motor can drive the jackshaft or crankshaft to move a device for adjustable passive exercise or other adjustable function. 
     Application of the adjustable drive to an elliptical cross trainer will allow the foot pedal path to be changed. Application of the adjustable drive to cycling will provide a wider range of motion for the feet and can develop more or less power to drive a vehicle. Use of the adjustable drive to a dependent stepper or tread climber will change the up and down motion of the foot supports. An upper body hand crank using the adjustable drive allows the hand motion to change without stopping the apparatus. 
     A control system can be used to change the actuator in all of the applications during operation of the apparatus according to a program. One such program applied to an elliptical cross trainer would provide for a short stride gradually increasing to a long stride during operation over some time interval. Alternately, an operator can select a different stride remotely by a control change. In the case of stationary cycling, multiple spinning bikes, each having the adjustable drive, would be controlled together by a class trainer to challenge the exercisers. 
     The adjustable drive provides a means to enhance versatility of a variety of exercise apparatus with the operator providing the force to drive the apparatus. Alternately, a motor can be attached to any of the applications to rotate the adjustable drive for an adjustable passive system to rehabilitate the arms and legs or other usage. 
     In summary, this invention provides the user with an adjustable drive that can be incorporated into a variety of exercise apparatus or other devices. A change of the adjustable drive will produce a different pedal movement to reduce the boredom of exercise, exercise different muscles or to accommodate different size operators. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view of the preferred embodiment of an adjustable drive constructed in accordance with the present invention; 
         FIG. 2  is a top view of the preferred embodiment shown in  FIG. 1 ; 
         FIG. 3  is a side view of a front drive elliptical cross trainer incorporating the adjustable drive shown in  FIGS. 1 and 2 ; 
         FIG. 4  is a side view of a rear drive elliptical cross trainer using the adjustable drive shown in  FIGS. 1 and 2 ; 
         FIG. 5  is a side view of a pole tread climber incorporating the adjustable drive shown in  FIGS. 1 and 2 ; 
         FIG. 6  is a side view of a recumbent exercise cycle incorporating the adjustable drive shown in  FIGS. 1 and 2 ; 
         FIG. 7  is a side view of an arm exercise apparatus incorporating the adjustable drive shown in  FIGS. 1 and 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Referring to the drawings in detail, the preferred embodiment of the adjustable drive is shown in  FIGS. 1 and 2  where adjustment arms  28 , 30  are attached generally opposed to adjustment shaft  45  which forms a pivot axis. Crankshaft  49  is positioned concentric with adjustment shaft  45  and supported by bearings  77 , 79 . Crank arms  20 , 22  are attached to crankshaft  49  in generally opposing directions. Crank links  24 , 26  are connected to crank arms  20 , 22  at pivots  25 , 27  and have drive pivots  21 , 23  positioned at the ends. Adjustment links  4 , 6  are connected to adjustment arms  28 , 30  at pivots  29 , 31  and to crank links  24 , 26  at pivots  41 , 43 . 
     Crank arms  20 , 22 , crank links  24 , 26 , adjustment arms  28 , 30  and adjustment links  4 , 6  combine to form a pair of crank linkages. A rotation of adjustment arms  28 , 30  relative to crank arms  20 , 22  cause the predetermined distance between the drive pivots  21 , 23  to change relative to the pivot axis  45 . Pulleys  8 , 12  are attached to crankshaft  49  which has a missing midsection. Pulley  10  is positioned in the missing midsection and is attached to adjustment shaft  45 . 
     Jackshaft  51  is positioned distal to pivot axis  45  and supported by bearings  81 , 83 . Pulleys  14 , 16 , 18  and  47  are attached to jackshaft  51 . Timing belt  13  engages pulleys  8 , 14  and timing belt  17  engages pulleys  12 , 18  causing crank arm  20  to rotate at the same speed as crank arm  22 . Timing belt  15  engages pulleys  10 , 16 , idler pulleys  62 , 66 , 68 , 72  and movable pulleys  64 , 70 . Idler pulleys  62 , 66 , 68 , 72  rotate about fixed pivots  61 , 65 , 67 , 71 . Movable pulleys  64 , 70  are connected to slider link  86  at pivots  63 , 69 . Slider link  86  is supported by slide bearing  80  to move back and forth relative to frame members  82 , 84 . 
     Belts  13 , 15 , 17 , pulleys  8 , 10 , 12 , 14 , 16 , 18 , 62 , 64 , 66 , 68 , 70 , 72  and slider link  86  form a belt assembly that can change the angular relationship between adjustment shaft  45  and crankshaft  49 . Actuator  76  is attached to frame  82 , 84  with threaded shaft  75  and threaded nut  74  connected to slider link  86  at pivot  73 . When actuator  76  receives a signal to move threaded nut  74 , slider link  86  will move causing pulley  10  to rotate relative to pulleys  8 , 12  which changes the predetermined distance between drive pivots  21 , 23  and pivot axis  45  along path  2 . Adjustment of the predetermined distance occurs with pulley  47  moving or stationary. Bearings  77 , 79 , 81 , 83 , slide bearing  80  and actuator  76  are supported by frame members  82 , 84 . Actuator  76  is electrically controlled by wiring  7  from a remote location. 
     A first application of the adjustable drive is shown in  FIG. 3  configured for a front drive elliptical cross trainer to change the path of pedals  50 , 52  from pedal curve  1  through pedal curve  3  to pedal curve  5 . Drive pivots  21 , 23  are connected to coupler links  96 , 98  which connect to foot support members  162 , 164  at pivots  93 , 99 . Rocker  160  is connected to coupler links  96 , 98  at pivots  193  and to frame  100  at pivot  91 . Rollers  104 , 106  are connected to foot links  162 , 164  at pivots  95 , 97  and in rollable contact with track  88 . Handles  92 , 94  for arm exercise move with coupler links  96 , 98 . 
     Pulley  47  drives speedup pulley  101  with belt  103  and belt  105  drives alternator/flywheel  107  for load resistance. Other forms of load resistance such as friction, magnetic, fan, etc. can provide the load resistance. Pedal motion and load resistance are adjusted by signals from control  102  through wires  7 , 9 , 11  by conventional means (not shown). 
     A second application of the adjustable drive is shown in  FIG. 4  configured for a rear drive elliptical cross trainer to change the pedal  350  motion from pedal curve  301  to pedal curve  303  and pedal curve  305  when actuator  76  moves slider link  86 . Crank  320  rotates about a second pivot axis  343  and is connected to drive link  304  at pivot  321 . Connecting link  324  is connected to drive link  304  at pivot  307  and to crank link  24  at drive pivot  21 . Pulleys  47  and  302  are engaged with belt  351  to rotate at the same speed. 
     Foot support  308  with pedal  350  is connected to drive link  304  at pivot  325  and to guide  310  at pivot  329 . Guides  310 , 312  connect to frame  300  at pivot  333  and extend upward to form handles  392 , 394  for arm exercise. Pulley  380  drives pulley  101  and alternator/flywheel  107  for load resistance. Control system  102  adjusts the pedal motion and load resistance through wires  7 , 9 , 11  by conventional means (not shown). 
     Another application of the adjustable drive is shown in  FIG. 5  configured for a tread climber with pole arm motion. Drive pivots  21 , 23  are connected to coupler links  412 , 414  which are connected to treadles  402 , 404 . Treadles  402 , 404  are connected to frame  400  at pivot  405  and support tread belts  406 , 408  at pivots  403 , 401 . Motor  440  controls tread belt  406 , 408  speed. Coupler links  412 , 414  extend upwards to become handles  492 , 494  to provide pole arm exercise. In this application, actuator  76  controls the amount of up and down movement of treadles  402 , 404 . Handle  410  is attached to frame  400 . Control system  102  controls the range of treadle  402 , 404  movement, load resistance at alternator  107  and tread belt  406 , 408  speed through wires  9 , 11 , 411  by conventional means (not shown). 
     Another application of the adjustable drive is shown in  FIG. 6  configured to change the motion of pedals  501 , 503  ( 503  not shown for clarity) for a recumbent bicycle. The operator is positioned in seat  513  where the feet move pedals  501 , 503  ( 503  not shown for clarity) which drives pulley  47  and alternator/flywheel  107 . Seat  513  is supported by frame  502  and can be repositioned by knob  505 . Handle  507  is attached to frame  502 . Control system  102  adjusts the motion of pedals  501 , 503  ( 503  not shown for clarity) and load resistance  107  through wires  9 , 11  connected by conventional means (not shown). 
     Yet another application of the adjustable drive is shown in  FIG. 7  for an upper body hand crank. Handles  510 , 511  ( 511  not shown for clarity) are connected to crank links  24 , 26  at drive pivots  21 , 23 . Moving handles  510 , 511  ( 511  not shown for clarity) cause pulley  47  to drive alternator/flywheel  107  as load resistance. Seat  513  is supported by frame member  514  which is attached to frame  512 . Control system  102  adjusts the diameter of handle  510 , 511  ( 511  not shown for clarity) movement through actuator  76  and load resistance  107  through wires  7 , 9 , 11  by conventional means (not shown). 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the claims, rather than by foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.