Friction gear transmission systems or components – Fluid control – Of toroidal transmission
Patent
1992-04-29
1993-09-07
Bonck, Rodney H.
Friction gear transmission systems or components
Fluid control
Of toroidal transmission
74474, F16H 3706
Patent
active
052423379
DESCRIPTION:
BRIEF SUMMARY
This invention relates to continuously-variable-ratio transmissions (CVT's) of the known toroidal-race, rolling-traction type, in which the transmitted ratio is determined by the variable orientation of rollers that roll in contact with a part-toroidal race formed on a rotating input disc, and with a similar race formed on a coaxial and contra-rotating output disc. The invention relates particularly to CVT's of this type in which the variable orientation of the rollers is determined hydraulically by the piston position of a hydraulic ram. Some essential components of such a CVT are illustrated schematically in FIG. 1A and 1B of the accompanying drawings, in which an input disc 1, formed with a part-toroidal race 2, is splined at 3 to an input shaft 4 rotatable about an axis 5. The splined connection at 3 causes disc 1 and shaft 4 to rotate together, but allows limited relative axial movement between them. An output disc 6 is mounted on an output shaft 7 which is also rotatable about axis 5. A part-toroidal race 8 is formed on disc 6 so that the surfaces of races 2 and 8 belong to the surface of a common torus formed about the same axis 5 as the shafts 4 and 7. A roller 10, which will typically be one of a set of three such rollers located at 120.degree. angular spacing around axis 5, rolls in contact with races 2 and 8, and an appropriate "end load", as indicated at 9, is exerted upon the discs to urge them axially-together and so achieve the necessary traction-transmitting reaction between the discs and the rollers. Both mechanical and hydraulic means of generating such an end load are well known in the art. By tilting the rollers 10 about a diameter as indicated by arrow 11, the transmitted ratio will be varied. With rollers 10 as shown, contacting input disc 1 at a large radius and output disc 6 at a smaller radius, output disc 6 will rotate faster than input disc 1 and the CVT will therefore be in "high" ratio. If rollers 10 are tilted to an opposite position in which they contact input disc 1 at a small radius and output disc 6 at a larger radius, the CVT will be in "low" ratio. As the arrowed detailed view shows, each roller 10 rotates about an axis 12 within a bearing 13 mounted on a roller carriage 14. In a manner which is known in the art, and shown by way of example in patent specification U.S. Pat. No. 4,662,248, the opposite ends of each carriage 14 of the set of three are formed as pistons 15 mounted to move within cylinders 16 and 17, and the two cylinders are connected by way of hydraulic lines 18, 19 with different outlets of a controlled valve system 20 which is itself in communication both with a source 21 of fluid under pressure and with a drain 22. Each carriage 14 and its cylinders 16, 17 are mounted so that the common axis 23 of the pistons and cylinders, which also constitutes a diameter of the roller 10, lies substantially tangential to the centre circle of the common torus of which the races 2 and 8 form part of the surface. The pistons 15 and with them the carriage 14 and roller 10 can not only move back and forth along axis 23. They can also rotate about the axis, and when they do so the radii (relative to axis 5) at which the rollers contact races 2 and 8 change also, thereby changing the transmitted ratio. As is well know in the art, such a CVT is in equilibrium when the sum of the reactions of each roller 10 against its races, resolved in a direction parallel to the axis 23, is balanced by the nett axial force exerted upon that roller by the fluid in the chambers of cylinders 16 and 17. If the equilibrium is disturbed, initiated either by a change of reaction at the disc/roller interfaces or by an operator demand on valve system 20 and a consequent change in the nett hydraulic force exerted upon the carriage by cylinders 16 and 17, the carriage will move axially, and this movement will be accompanied by a rotation and a change in transmitted ratio until equilibrium is restored at the appropriate new ratio.
A hydraulically-operated CVT, having features of the kind just describe
REFERENCES:
patent: 3142189 (1964-07-01), Caldwell et al.
patent: 4056989 (1977-11-01), Shaffer
patent: 4086820 (1978-05-01), Krauss et al.
patent: 4170438 (1979-10-01), Kondo et al.
patent: 4275610 (1981-06-01), Kraus
patent: 4297918 (1981-11-01), Perry
patent: 4434675 (1984-03-01), Kraus
patent: 4524641 (1985-06-01), Greenwood
patent: 4662248 (1987-05-01), Greenwood
patent: 4698971 (1987-10-01), Sansone
patent: 5090951 (1992-02-01), Greenwood
Bonck Rodney H.
Massey Ryan W.
Torotrak (Development) Limited
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