TRANSMISSION SYSTEM FOR PEDAL POWERED MACHINES

Abstract: An improved transmission system for pedal power machines, taking advantage of the non-uniform motion transmitting characteristics of the well known "universal" type joint (8, 9). By coordinating pedal crank lever arm length to the torque modification achieved using these joints, an improved transmission is had, which leads to overall reduction in rider fatigue. The power train consists of input pedal shaft (10), gears (1, 2, 3, 4), all mounted in housing (12), with chain wheel (5) as the output.

Description: TRANSMISSION SYSTEM FOR PEDAL POWERED MACHINES TECHNICAL FIELD " - This invention relates t a transmission system for pedal powered machines intended to reduce physical fatique and improve one's capacity to . • • perform work. BACKGROUND ART Conventional devices exist that make it possible to change speed transmission ratios in pedal powered machines ' such as bicycles. These devices which . are intended to improve machine. efficiency, belong either to the derailleur or french- type changespeed gear tha-t uses multiple sprockets on the rear wheel . and a spring-loaded idler pulley .to transfer the ■chain from one sprocket to another while pedalling or to the british type which consists of a miniaturized gear box i bodied in the hub ' of the back wheel. " DISCLOSURE OF INVENTION • ' None of these devices s however, solve the problem . of effort concentration during relatively short .periods of time when pedals come across certain regions of their cyclic motion. The said regions of cyclic motion are herein designated "active regions" for facility of description and co prehention. During said periods of time when pedals come across such active regions energy transmission is favoured by a longer lever projection in the normal direction to the force exerted on the pedals. As the ped ' aTs move on from an active region into what is herein designated as a passive region they move idly for a period of time during which pracli.cally no force can be exerted^-oo them due to the fact that lever length projection is reduced to almost zero. Thus, the total work performed in the period --of a complete cycle has to be transferred to the machine during a relatively " small fraction of the said period and the mover, that -is, the cyclist, has to wait until pedals move again into an active region and so on. This process has a well known effect that is: the concentration of effort done by ' the cyclist causes his physical fatigue. The herein described invention is intended to solve the previously mentioned problem in a simple reliable manner by equipping pedal powered machines with a device capable of enlarging the period of -time during which pedals stay in an active region and reducin§*-the period of time during which they stay in-. • a passive region, without changing the .period of a - complete cycle and thus keeping the same average . transmission ratio. . The use of herein described device allows the same- amount of work to be performed along a complete. cycle of the movement of pedals to be transferred to the machine during a longer period of time, which corresponds clearly to a lower power peak exerted by the cyclist, and therefore to low?r physical fatique. It follows, on the other hand, that for a certain power peak capacity of the cyclist, that is, for the same physical fitness, he will be able to perform more work during a complete cycle if the machine is equipped with herein described device than if it is not. From the foregoing statement one can conclude that the cyclist will be able to pedal uphill along steeper slopes as well as to keep higher speeds on a horizontal plane if his machine, is equipped with herein described device then with conventional machines with the same average transmission ratio. It should be emphasized that herein described invention is by no means incompatible with conventional change-speed- gears such as the ones previously mentioned, namely the french and british types, whose 05 efficiency can actually be i pro.ved by its use. The previously described effect can be achieved, according to the present invention, by equipping the machine with a device that consists basically of one or several so called "universal" or HOOKE or CARDAN 10 joints or equivalent. By this means one takes advantage of the well known disadvantage of this type of joint, which is that of non uniform transmission of a uniform source- movement, as a funtion of the angle between mover and moved joint axes, yet keeping 15 the same average speed. Thus the moved axis will have, instantaneous speeds .that are lower than the ' average .speed during certain periods of time and higher than the ' said average speed during other periods of time along the same cycle. This has a new surprising 20 effect upon the transmission .systems of pedal machines such as of bicycles.: ' ' • ' - BR T -EF DESCRIPTION Of DRAWINGS . * _ " ..- ' ' An embodiment of the invention will now be described, by way of example, with reference ' to the 25 accompanying drawings, in which: Fig. 1 is a graphic display showing comparative . performance of a conventional machine and that of a machine modified according to the invention; - Fi ; 2 represents a lateral view of an example of 30 a pedal machine which, in this case, is a bicycle; • Fig. 3 is a lateral view of a pedal hub including a device consisting of two joint ' s of the so called . "universa! " type connected in series; . OM Fig. 4 V i.s an upper view of the mechanism of fig. 3; - : ' . ' Fig. 5 is a back view of- ^ the mechanism of figs. 3 and 4; 05 Figure 1 displays velocities and powers in the vertical axis against time in the horizontal axis. Curves 1A an -IB correspond respectively to velocity arid power variations in a conventional pedal machine and curves 2A and 2B correspond to velocity and power 10 variations in a machine modified according to the • present invention. The work transferred to the conventional machine along the active region of half a cycle of movement of pedals equals the shaded area under- curve IB. Then folϊow-s a passive region 1C during 15 .which no- 'work can be transferred to the system. Then - again the pedals ' reach an active region and so on. - Curve 2A represents the velocity variation of the.modifie machine around the same average velocity VM. In this. case the period of time corresponding to the active 20 region is longer while the pedal - stay. " in the -passive region for a shorter period of time 2C. As the average • velocity is the same .as in curve IB the work corresponding to shaded area under curve " 2B is the same as -that corresponding to shaded area under curve IB -25 except for* s.m ll differences associated with friction losses. It follows, however, that the equival ent " sha'ded areas under IB and 2B correspond to different power peaks, power- peak in 2B being .smaller than in IB. Figure 2 represents a pedal powered machine whose 30 modified pedal hub is detailed in figs. 3, 4 and 5. Figure 3, 4 and 5. represent,- respectivel , the upper, lateral and back views of the modified pedal hub of the machine i fig. 2. . Sprockets and chains may eventually take the place of cilindrical gears 1, 35 2, -3 and 4 without altering the essence of proposed device. Gear 1 is fixed to pedal axis, mover axis, 10, meanwhi le 'gear.4 is fixed to the pedal sprocket .5 and idle with respect to the pedal axis 10. Gears 2 and 3 have parallel non coincident \vxes and are connected to each other by two shafts 6 and 7 and two "universal" joints 8 and 9 in such a way that the angles between shaft 7 and the axes of gears 2 and 3 be equal to each other and different from zero, as shown in fig. 5. The two- oints, have to be assembled in. such a way as to sum up their non-uniform transmiss on effect instead of their.- cancel 1 ing out each other. The device .works as ' if there were . one single joint with mover and moved axes , at a .fictitious angle, here-n designated equivalent operation angle. All described elements are protected bv hub body 12. ■ • OMPI

Claims: CLAIMS 1. A transmission system for pedal powered machines essentially consisting of an assembly of one or-more "universal" or "CARDAN" or "HOOKE" joints connected together in series and assembled in such a way that one extremity of the joint or set of joints is connected to the mover- axis the other extremity being connected to the pedal sprocket, gear or shaft that transmits the final rotary movement.

Inventors: GONCALVES EDUARDO MACHADO, GONCALVES, EDUARDO, MACHADO
Applicants: GONCALVES EDUARDO MACHADO, GONCALVES, EDUARDO, MACHADO
Application year: 1983
Main classification: G05G1
IPC codes: B62M23, F16H35