Land vehicles – Wheeled – Occupant propelled type
Patent
1994-04-11
1996-08-27
Hill, Mitchell J.
Land vehicles
Wheeled
Occupant propelled type
280236, 474141, B62M 908
Patent
active
055493149
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a non-circular front chain wheel for crank gear.
It mainly concerns the cycle industry but may also find applications in other fields, such as physical exercise apparatus for body-building or rehabilitation, and in general, all apparatus using cycling motion and a chain or belt transmission system between the front wheel or wheels of the crank gear and one or a plurality of pinions actuating the device to be driven.
In apparatus of this type, the load moment, or in other words, the force exerted by the chain on the front chain wheel of the crank gear can be thought to be substantially constant, whereas the driving torque produced by the cyclist, is variable by nature, passing cyclically from a lesser value at the upper and lower dead points when the arms of the pedals, or the cranks, are aligned with the saddle and the axis of the crank gear, and a maximum value when the arms are substantially horizontal.
For obvious reasons of ease, most often circular front chain wheels are used, resulting in numerous disadvantages: points and loss of power, causing an increase in cardiac rhythm, axis of the dead points, and is not a function of human ability, disproportionate muscular, tendon and joint efforts, thereby limiting performance as well as pleasure, variations, overload, which results in energy loss in the dynamic effects on the legs, effort provided by the cyclist, pedal, subject to substantial variations in effort.
A number of efforts to improve crank gear functioning have been suggested. For example, FR 83 09 015 describes an elliptical front chain wheel for a crank gear whose biggest radii correspond to the dead points. The foremost objective of this device is to obtain greater speed, but as it does not take into account muscle characteristics, it results in an increased variation in the efforts to be provided and increased tiredness, without, however, obtaining satisfactory results.
DE-A-3 709 482 and DE-U-8 522 573 also describe non-circular front chain wheels. These documents may seem to represent a slight improvement from the energy point of view, but by virtue of their geometry, do not enable the load moment of the front chain wheel to correspond with the potential possibilities of muscular forces that inherently characterize human anatomy.
SUMMARY OF THE INVENTION
The device as per the present invention eliminates all of these disadvantages. As a matter of fact, it enables more natural pedalling by adapting, for each pedal position, the radius of the front chain wheel of the crank gear in accordance with the following parameters:
It is constituted by a crank gear wheel enabling the cycling torque to be increased progressively from the dead point up to the point where the extension of the leg allows creation of the maximum effort, by virtue of a progressive variation of the primitive radius of the toothing between these two points, followed by a rapid decrease to the next dead point. The principle is that the force to be provided is proportional to the muscular force that the user may provide.
BRIEF DESCRIPTION OF THE DRAWINGS
In the annexed drawings, provided as non-limiting examples of one of the embodiments of the object of the invention:
FIG. 1 represents a serrated front chain wheel with pedals at the upper dead point, the tangent point of the stretched portion of the chain corresponding substantially to the smallest radius,
FIG. 2 shows the same front chain wheel at the point of greatest effort, the tangent point corresponding substantially to the biggest radius, and
FIG. 3 illustrated another embodiment of the invention wherein a belt is utilized instead of a chain.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The device, FIGS. 1 and 2, is constituted by a serrated front chain wheel 1 activated by two traditional pedals 2, 3, and driving a chain 5, also traditional.
If one were to consider FIG. 1, the left portion of front chain wheel 1 is divided into several zones demarcated by angles measured from the point at which
REFERENCES:
patent: 515449 (1894-02-01), Scovell
patent: 3899932 (1975-08-01), Durham
patent: 4133550 (1979-01-01), Brown
International Preliminary Examination Report in French.
International Search Report in English.
Sassi Michel
Talo Jean-Louis
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