Rectilinear pedal movement drive system
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a drive system, and more particularly, to a propulsion system for a bicycle, or the like, having a vertically oriented, rectilinear motion path, wherein the rectilinear motion is converted to a rotary motion. 
     2. Description of Related Art 
     Humankind has long aspired to achieve a more physically fit body. Devices of all sizes, shapes and configurations have been created with this purpose in mind; exercises designed to develop specific muscles in particular ways have been designed by scientists, doctors, engineers and the weekend athlete. Some of these machines and techniques improve strength, some improve conditioning and others improve muscular tone. 
     Regardless of this multitude of mechanisms and techniques, many deficiencies yet exist with many physical conditioning devices. Such deficiencies include non-efficient application of muscle strength from the human body to the object of the exercise as well as lost power transference. Bicycles illustrate a class of widely used exercise machines which have been the subject of various refinements. Athletes often employ bicycles for exercise as well as competition. Bicycles are also used in many countries as a mode of transportation, in addition to a means of exercise. While bicycle manufacturers have sought to produce lighter bicycles, more flexible bicycles and more durable bicycles through the use of a variety of materials, the conventional bicycle continues to employ a less than completely efficient drive train. Although this area has received considerable attention in recent years a more efficient exercise and transportation apparatus yet remains to be developed. 
     Conventional bicycles incorporate an axle located approximately midway between the front and rear tires. Perpendicularly affixed to the axle are shafts, at the end of which are pedals that project outwardly from the bicycle. The pedals allow the user to utilize the propulsive power generated by the human body. The axle usually has a sprocket that engages a chain driving the rear tire, and which propels the bicycle forward. Thus, the axle, shaft, pedal configuration of the bicycle drive mechanism to force the rider to drive his or her feet and legs in a generally circular motion. This motion while effective in creating sufficient force to propel the bicycle forward, does not do so with maximum efficiency. 
     The rotational motion forced upon a rider by the drive mechanism of a conventional bicycle results in lost motion and wasted energy. The bicycle&#39;s drive is developed from the downward push of the rider&#39;s legs and feet along the circular path of the pedals, and the circular path makes it difficult for the rider to exert a constant propulsive force. This inherent lost motion problem decreases the rider&#39;s ability to pace himself or herself during a long journey. Thus, a drive system which eliminates lost motion and increases the length of the power stroke would be a marked advance over the prior art. The present invention accomplishes this goal, while increasing power uniformity and decreasing the length of the rider&#39;s reset stroke. In addition, the improved drive system results in a more efficient means for the application of propulsive power and for increasing the endurance of the rider. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a drive system for converting rectilinear motion to rotary motion. In one aspect, the invention includes an improved bicycle drive system of the type wherein bicycle pedals are driven by the feet of a rider in opposite directions for rotating a drive sprocket which is coupled to, and drives, a wheel sprocket thereby propelling the bicycle in a forward direction. The improvement comprises a means for mounting the pedals to create oppositely disposed rectilinear motion. A means for producing a first bi-directional rotary motion in response to rectilinear actuation of each of the pedals is provided and is linked to the pedals. Also provided is a means for transducing the primary bi-directional rotary motion into a secondary uni-directional motion. The secondary uni-directional motion is coupled to the drive sprocket by a coupling means and results in the propulsion of the bicycle. 
     In another aspect, the invention includes a drive system comprising a pair of vertically oriented, parallel rectilinear motion guide. A pair of force blocks are separately and slidably mounted on the motion guides. Means are provided for reversibly oscillating the force blocks, wherein the force blocks are disposed at opposite ends of the parallel rectilinear motion guides. A drive force resistance means is coupled to the force blocks. Means are then provided for transferring the drive force from the force blocks to the resistance means when a rectilinear force is applied to the force blocks. A unidirectional clutch means links, and is disposed between, the transfer means and the force blocks for transferring the drive force in a single direction for the generation of rotary motion. 
     In another aspect, the invention includes the drive system described above wherein the transfer means comprises an idler axle mounted at one end of the parallel rectilinear motion guides and having two idler sprockets. One of the idler sprockets is linked to one of the force blocks, with the other of the idler sprockets being linked to the other of the force blocks. A drive axle is mounted at the other end of the parallel rectilinear motion guides, with the drive axle being aligned parallel to the idler axle. The drive axle comprises a shaft having a drive wheel mounted thereon for rotation therewith and a pair of driving sprockets also mounted thereon. The drive axle further is coupled to the unidirectional clutch means, wherein the unidirectional clutch means is mechanically interconnected to one of the pair of driving sprockets. The other of the pair of unidirectional clutch means is mechanically interconnected to the other of the pair of driving sprockets. Furthermore, one of the pair of driving sprockets is linked to one of the force blocks, with the other of the pair of driving sprockets being linked to the other of the force blocks. Each of the force blocks is connected to one of a pair of drive chains which link the idler sprockets, the drive sprockets and the force blocks together. The drive chains are trained around one of the idler sprockets and drivingly trained around one of the driving sprockets. The driving sprockets function unidirectionally, thus providing a drive force in only one direction. The unidirectional clutch means causes the driving sprockets to actively engage the drive axle when turned in the proper direction. 
     In another aspect, the above described invention is constructed with the pair of parallel rectilinear motion guides mounted on a bicycle frame, with the drive wheel connected to the rear bicycle wheel thereby transferring a propulsion force thereto. An outer housing covers the mechanics of the apparatus. The outer housing defines a guide for the horizontal member protruding from the force block. The outer housing also includes an arcuate mounting guide which is adjustably fixed to the bicycle frame. 
     In an alternative embodiment, the bicycle may be a stationary bicycle, for example of the type used for exercise, rather than a conventional bicycle. As used herein, the term &#34;bicycle&#34; refers to both stationary and conventional bicycles. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may be better understood and its numerous objects, features and advantages become apparent to those skilled in the art by referencing the accompanying drawings in which: 
     FIG. 1 is a side elevational view of a bicycle having incorporated thereon a drive system constructed in accordance with the principles of the present invention; and 
     FIG. 2 is an enlarged, fragmentary, perspective view of the drive system of FIG. 1 illustrating the mechanical linkage for converting rectilinear motion to rotational motion. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring first to FIG. 1, there is shown a side elevational view of a bicycle 18 having a vertically oriented, rectilinear travelling drive system 10 constructed in accordance with the principles of the present invention. The bicycle 18 is assembled with an upper frame member 20 extending from a front frame member 22 to a rear frame member 24. Below the upper frame member 20 is an apparatus support bracket or frame member 14, which also extends from the front frame member 20 to the rear frame member 24. The lowermost end of the rear frame member 24 intersects with the lower end of the drive system 10. The rear wheel 28 is mounted between the rear fork 30. The rear fork 30 extends from the point of engagement between the rear frame member 24 and the rectilinear travelling drive system 10. The front wheel 32 is mounted between a front fork 34. The front fork 34 extends from the bottom of the front frame member 22. 
     The drive system 10 includes an outer housing 12 in which the mechanics of the drive system 10 reside. The outer housing 12 of the drive system 10 is affixed at its uppermost portion to a mounting bracket 36. The mounting bracket is affixed to the apparatus support bracket or frame member 14. The outer housing 12 is mounted to the mounting bracket 36 by means of an arcuate slotted guide 16. The mounting bracket 36 projects from the underside of the apparatus support bracket VC3 or frame member 14 and receives an adjustably secured pin 38, which passes into the arcuate slotted guide 16. Once in place, the adjustably secured pin 38 is tightened to provide frictional engagement between the arcuate slotted guide 16 of the drive system 10 and the mounting bracket 36. 
     The lowermost end of the drive system 10 is secured to bicycle 18 at the lowermost portion of the rear frame member 24. Drive axle 50 projects into the outer housing 12 and through the bicycle frame. Thus, drive axle 50 holds the lower end of the drive system 10 in place. The drive axle 50 rotates within the bicycle frame and permits the outer housing 12 to pivot about the drive axle 50. By employing the adjustably secured pin 38 in coordination with the arcuate slotted guide 16, the mounting bracket 36 and the pivoting attachment of the drive axle 50, the outer housing 12 of the drive system 10 may be angularly shifted. As a result, the outer housing may sit completely vertical within the bicycle 18, or the rider may shift the outer housing 25 degrees forward or 25 degrees to the rear. The angular shift is illustrated by notional lines 52 and 54. 
     Still referring to FIG. 1, there is shown two foot pedals 56 and 58. The foot pedals 56 and 58 travel within the pedal guide 60 located on either side of the outer housing 12. As foot pedal 56 is pushed downward by the rider, foot pedal 58 will automatically rise within the pedal guide 60. The up and down motion of the foot pedals 56 and 58 causes the internal mechanics of the drive system 10 to turn the drive axle 50. Drive sprocket 62 is fixedly attached to the drive axle 50, such that the rotation of the drive axle 50 causes the drive sprocket to rotate as well. Drive chain 64 engages the drive sprocket 62 and transfers the drive energy from the drive system 10 to the rear wheel 28 by means of the rear drive gears 66. 
     Referring now to FIG. 2, there is shown a perspective view of the rectilinear travelling drive system 10 mounted within the frame of the bicycle 18. The outer housing 12 is shown in phantom such that the internal mechanics of the drive system 10 can be viewed. Mounting screws 100 secure the outer housing to the two parallel rectilinear motion guides 102, 104. The two parallel rectilinear motion guides 102 and 104 comprises the frame for the drive system 10. Cross-frame members 106 fixedly connect the parallel rectilinear motion guides 102 and 104, thereby creating the necessary structural strength. 
     The force block 108 is slidably mounted upon the rectilinear motion guide 102, while the force block 110 is slidably mounted upon the rectilinear motion guide 104. The force blocks 108 and 110 include a number of force block rollers 112. The force block rollers 112 are located about the force blocks 108 and 110. The force block rollers 112 slide along the rectilinear motion guides 102 and 104, thus enabling the force blocks to move along the rectilinear motion guides 102 and 104. Further included on the force blocks 108 and 110 are cable clamps 114 and 115. The cable clamp 114 secures flexible cable 116 to the force blocks 108 and 110. Located on the opposite side of the force blocks 108 and 110 from each of the cable clamps 114 and 115 are chain clamps 118 and 119 which secure the power transference chains 120 and 122 to the force blocks 108 and 110. Further included upon the force blocks 108 and 110 are horizontal force receiving bars 124 and 126. The force receiving bars 124 and 126 project orthogonally from the force blocks 108 and 110 and are provided so that the user can apply the drive force intended. In the preferred embodiment, foot pedals 128 are mounted on the force receiving bars 124 and 126. 
     Still referring to FIG. 2, there is illustrated upper direction reversing wheel 130 and lower direction reversing wheel 132. The flexible cable 116 is trained about the upper direction reversing wheel 130 and the lower direction reversing wheel 132, forming a closed loop. The upper direction reversing wheel rotates about upper reversing wheel axle 134, while the lower direction reversing wheel 132 rotates about lower reversing wheel axle 136. The flexible cable 116 passes through each of the cable clamps 114 and 115, thereby affixing the force blocks 108 and 110 to the flexible cable 116. The flexible cable connects the force blocks 108 and 110 in order to maintain their oppositely disposed positions along the parallel rectilinear motion guides 102 and 104. Thus, when a downward force is applied to the force block 108, it causes the flexible cable 116 to move as well. The movement of the flexible cable 116 pulls the force block 110 upward along the rectilinear motion guide 104. Consequently, a force on one of the force blocks 108 or 110 causes the other force block to automatically move in the opposite direction along the rectilinear motion guide upon which it is mounted. As a result of this automatic oscillation, the two force blocks 108 and 110 maintain their oppositely disposed positions. The upward movement of the force block 110 is terminated by force block stop 138 which is mounted upon rectilinear motion guide 104. Force block stop 140 terminates the upward movement of force block 108. 
     As the force blocks 108 and 110 oscillate up and down along their respective rectilinear motion guide 102 or 104, the power transference chains 120 and 122 are driven along their loop. The power transference chain 120 begins its loop at the chain clamp 118 affixed to the force block 110. The power transference chain 120 then engages the teeth of idler sprocket 142 and proceeds to the teeth of power sprocket 148. The idler sprocket 142 is mounted on the idler axle 146, which is affixed to the inner wall of the outer housing 12 and runs perpendicular to the parallel rectilinear motion guides 102 and 104. The idler sprocket 142 is mounted on one end of the idler axle 146 and a second idler sprocket 144 is mounted on the opposite end of the idler axler 146. The idler sprockets 142 and 144 are mounted on idler bearings 152 and 154 which are directly mounted on the idler axle 146. The idler bearings 152 and 154 permit the idler sprockets 142 and 144 to rotate in either a clockwise or counter-clockwise direction. 
     The power transference chains 120 and 122 engage the power sprockets 148 and 150 at the lower end of the drive system 10. The power sprockets 148 and 150 are mounted on unidirectional clutches 156 and 158, which, in turn, are mounted upon the drive axle 50. The unidirectional clutches 156 and 158 enable the drive axle 50 to turn when the power sprockets 148 and 150 are rotated in the proper direction (clockwise) by the power transference chains 120 and 122. Thus, when the power transference chain 120 is rotated clockwise, e.g., the power block 110 is pushed down, the unidirectional clutch 156 is not engaged and allows the power sprocket 148 to turn the drive axle 50. At the same time, the power block 108 is pushed up, which causes power sprocket 150 to rotate counter-clockwise, thereby engaging the unidirectional clutch 158 which prevents the power sprocket 150 from attempting to rotate the drive axle 50. Consequently, there is always a rotational force being applied to the drive axle 50 by either one of the power sprockets 148 or 150. In this way the drive sprocket 62 is turned and causes drive chain 62 to rotate rear drive gears 66. 
     Thus, there has been described and illustrated herein a drive device. Those skilled in the art, however, will recognize that many modifications and variations besides those specifically mentioned may be made in the techniques described herein without departing substantially from the concept of the present invention. Accordingly, it should be clearly understood that the form of the invention as described herein is exemplary only and is not intended as a limitation on the scope of the invention.