Endless belt power transmission systems or components – Pulley with expansible rim means or pulleys with alternately... – Structure for variably adjusting radius of rim section
Patent
1995-09-11
1997-11-18
Schoeppel, Roger J.
Endless belt power transmission systems or components
Pulley with expansible rim means or pulleys with alternately...
Structure for variably adjusting radius of rim section
474 52, F16H 910
Patent
active
056881991
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a variable ratio drive mechanism of a type which is suitable for use in bicycles and other energy transmission systems.
A person driving a bicycle on a flat road will use a certain gear ratio for a comfortable ride. The gear ratio is fixed. The gear ratio is defined as the ratio of the diameters of the chain drive pulley 2 (at pedals) and the chain sink pulley 1 (at the rear wheel), see FIG. 1 (r/R).
The largest diameter wheel of the wheels combination with multiple diameters on the left side of the FIG. 1 is the energy input. The single diameter wheel to the right is the energy sink or load. This single diameter wheel could be a multiple diameter wheel arrangement (as illustrated on the left side). This would increase the available gear ratios. Such arrangements are well known from bicycles.
As the cyclist moves onto a slope he will deliver more torque (force exerted on the pedal multiplied by the radius of the drive pulley) to climb.
Feeling this demand for increased torque (force needed by his legs to turn the drive pulley) and probably exceeding his capacity to push, will cause the cyclist to manually change the gear ratio (if he is lucky to have a multi-level gear system on his bicycle).
Bicycles with multi-gear systems have become in the past very popular by use on mountain bikes and they are sold by the million.
An automatic, stepless gear shift device responding to the input torque would greatly simplify handling of a bicycle.
The continuous torque to gear ratio adaptation would enable matching of the energy source characteristic (torque/rpm) to the energy load characteristic. If the adaptation curve fitted well between supply and load, then the total energy available would be transferred optimally into the linear motion.
The above refers to a chain drive as found on bicycles.
The present invention also applies to other types of energy source, like gasoline or diesel engines, electric motors, water turbines, and so on. It would simplify the task of adapting the energy source to the energy load.
Automatic transmissions for automobiles have been known for a long time. However, their technical realization is complex and expensive and there are still only certain discrete levels of gear ratios available.
Hydraulic continuous torque converters are known, but their hydraulic slip is of disadvantage for continuous use due to friction and consequently lower transmission efficiency.
Usual automatic transmissions change between specific gear ratios. The gear changing procedure is automated and torque and rpm controlled. Multiple discrete gear ratios allow a better adaptation between the source and load characteristics, but it is still not a continuous optimized adaptation.
A development of an automatic and continuous gear ratio system was known in the past to be in some stage of introduction to small cars. In this arrangement a v-type belt moved radially in and out between two flanges moving axially and driving the v-belt on its side (shoulder). Flanges moving closer would squeeze the v-belt to move to a larger diameter circle and the gear ratio increases.
This development was for some time in series production, but its technical problems seem to have put it again out of the market, or at least it did not succeed in entering the market in substantial numbers.
The proposed invention presents now a reliable, inexpensive and simple mechanical solution to form a continuous ratio shifting gear system.
One aspect of the present invention provides a variable ratio drive mechanism including at least one gear whose effective radius is variable in a stepless manner.
The gear could be the pedal driven gear of a bicycle chain drive mechanism, in which case torque is applied through the pedals, or the driven gear in which case torque is applied via the chain itself.
The gear may take the form of a spiral spring, preferably wound in the direction opposite to its direction of rotation.
Alternatively, the gear may take the form of a circular rim, mounted on an axle by means of radially exten
REFERENCES:
patent: 2584447 (1952-02-01), Hayot
patent: 3605512 (1971-09-01), Wetzel, II
patent: 3935751 (1976-02-01), Lee
patent: 4498351 (1985-02-01), Ahoor
patent: 4516960 (1985-05-01), Rathert
patent: 4608034 (1986-08-01), Reswick
patent: 5407395 (1995-04-01), Kramer
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