Planetary gear transmission systems or components – Planet periphery surrounds axis of interacting gear – Friction gearing
Patent
1991-01-29
1991-12-10
Wright, Dirk
Planetary gear transmission systems or components
Planet periphery surrounds axis of interacting gear
Friction gearing
475170, F16H 128
Patent
active
050713930
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a transmission and particularly to a transmission which has a wide range of speed reduction and the speed is variable within that range in a continuous or non-stepwise manner.
There has previously been proposed a very wide variety of speed reduction transmissions, wherein the reduction ratio can be varied within wide limits and in a continuous manner. The majority of these prior proposed constructions are complex in construction and usually incorporate a number of gear components which are costly to manufacture and difficult to achieve low noise and vibration levels in operation.
It is the object of the present invention to provide an improved transmission which provides a continuously variable ratio within limits, is relatively cheap to manufacture, and effective and reliable in operation.
With this object in view, there is provided according to the present invention a variable ratio transmission comprising a co-axially arranged stationery housing and relatively rotatable input member, a floating eccentric mounted on the input member and having an external cylindrical surface, said floating eccentric being supported to rotate with the input member and being displaceable relative to the input member to vary the cylindrical surface between coaxiality with the input member and a maximum preset eccentricity thereto, a driven member having internal and external coaxial cylindrical surfaces and rotatably supported on the floating eccentric with the external cylindrical surface of the floating eccentric in concentric rolling engagement with the internal cylindrical surface of the driven member, said housing having a variable diameter internal cylindrical surface in rolling engagement with the external cylindrical surface of the driven member, and an output member mounted in the housing to rotate relative thereto about an axis parallel to the driven member, said output member being coupled to the driven member so that the said output member rotates in response to the planetary movement of the driven member, and means to control the diameter of said internal cylindrical surface of the housing over an operating range to vary the rotational speed ratio between the input and output members, said operational range of the diameter of the variable internal surface of the housing having a lower limit not less than substantially equal to the diameter of the external cylindrical surface of the driven member and an upper limit not more than the sum of the diameter of the external cylindrical surface of the driven member and twice the preset maximum eccentricity of the floating eccentric.
Preferably said variable diameter internal surface is defined by a plurality of elements supported in the housing for relative linear movement thereto, and spaced about the axis of input member. Conveniently the means to control the variable diameter of the internal cylindrical surface of the housing comprises at least one annular member mounted in the housing co-axial with the input member for axially movable relative to the housing. Said annular member and the elements being adapted whereby the axial movement of the annular member in one direction will effect radial movement of the elements to reduce the diameter of the variable internal cylindrical surface.
In one embodiment an output member is mounted in the housing to rotate relative thereto about an axis parallel to the input member, said output member being coupled to the driven member so that the said output member rotates in response to the planetary movement of the driven member. Conveniently the output member has a plurality of drive pins mounted thereon projecting in a direction parallel to the output member axis. The drive pin being equally spaced along a circular path co-axial with the output member axis. A plurality of apertures are provided in the driven member, equal in number to the pins and equally spaced about a circular path co-axial with the driven member axis and equal in diameter to the circular path of the pins. The apertures being o
REFERENCES:
patent: 2035582 (1936-03-01), Winger
patent: 3190148 (1965-06-01), Flichy
patent: 4497221 (1985-02-01), Koser
patent: 4505163 (1985-03-01), Falkner
patent: 4920827 (1990-05-01), Takamiya et al.
patent: 4924730 (1990-05-01), Parsons
patent: 5013288 (1991-05-01), Parsons
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