Land vehicles – Wheeled – Occupant propelled type
Patent
1996-03-11
1999-03-16
Boehler, Anne Marie
Land vehicles
Wheeled
Occupant propelled type
301 51, 301 56, 301104, G60B 104
Patent
active
058820264
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a drive mechanism particularly for use in rotary drive systems.
TECHNICAL FIELD
The invention is to be applied to rotary drive systems in which a driven member such as for example a wheel, a propeller, a rotatable blade and other forms of apparatus are intended to be driven for rotatory movement from a remote manual driving means. The driving means may consist for instance of a handle or handles or pedals which are linked by transmission means to the driven member so that rotation of the driving means will result in rotation of the driven member. A specific application of the rotary drive system is in relation to a pedal driven conveyance such as a pedal bicycle or tricycle.
The driven member is generally arranged to be driven from a remote location by a transmission means such as a drive belt or a chain which passes over a belt pulley or sprocket attached to the driven member and over a driving pulley or sprocket so journalled that the drive pulley sprocket can be manually turned by pressure exerted by the legs or arms of the operator. In many instances it is desirable to vary the ratio of the speed of rotation of the driven member to that of the drive pulley or sprocket for the purpose either or increasing the speed of rotation of the driven member in relation to the drive pulley or sprocket or of decreasing the speed and thereby allowing an increased torque to be applied to the driven member. Various means as are known in the art are employed for this purpose. One such means comprises a series of stepped pulleys of varying diameters where the transmission means is in the form of a flexible belt or a series of stepped sprockets of varying diameters where the transmission means is in the form of a chain.
In the case of a pedal conveyance such as a bicycle, the speed varying means generally consists of a series of sprockets of varying diameters fixed to the driven wheel and a series of drive sprockets of varying diameters so that the link means which is generally a chain, can be moved to mesh with a selected pair of sprockets to obtain the optimum speed of rotation of the driven wheel in relation to the drive sprocket.
While it is possible to improve the torque applied to the driven member by means such as that hereinbefore described, nevertheless it is highly desirable that means be provided so that the amount of torque can be increased to an optimum value by means other than the known gear multiplication ratios.
OBJECT OF THE INVENTION
It is therefore an object of this invention to provide an improved drive mechanism for a rotary drive system of the kind described.
DISCLOSURE OF THE INVENTION
Accordingly, one form of the invention comprises a rotary drive mechanism including a driven member having a hub and a rim substantially coaxial with and supported by said hub which is adapted to be journalled to a frame to allow rotation of the driven member in relation to the said frame, characterized in that the driven member includes a transmission hub co-axial with said hub and at least two transmission cables each having one end anchored to said transmission hub to extend substantially tangetially from said transmission hub at a position substantially 180 .degree. opposite each other and each having the other end passing around a guiding sheave supported by a first pulley block attached to said rim and extending from the said pulley block towards and anchored to a second pulley block in a direction opposite that in which the driven member is to be rotated.
Preferably the pulley blocks are equidistantly spaced from each other on the said rim.
Preferably each pulley block includes main sheave, a guiding sheave and an anchor point and wherein each transmission extends form the transmission hub around the main sheave and over the guiding sheave and has its distal end anchored to the anchor point of a contiguous pulley block.
Preferably the drive mechanism includes four anchor points on said transmission hub, with each anchorage point being equidistantly spaced on a notiona
REFERENCES:
patent: 1272723 (1918-07-01), Sullivan
patent: 1653612 (1927-12-01), Baker
patent: 2378154 (1945-06-01), Nelson
patent: 4917162 (1990-04-01), De Longcamp
patent: 5110190 (1992-05-01), Johnson
Boehler Anne Marie
Vigil Thomas R.
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