Torotrak (development) Limited

Allison Transmission, Inc.

Torotrak Limited

Andrew Damian De Freitas

Brian Joseph Dutson

Christopher John Greenwood

John Fuller

Robert Andrew Oliver

James Shawe

A dual-cavity toroidal variator is disclosed herein. The torques from the first and second cavities are balanced by controlling each roller with mechanical devices rather than individually controlling each roller with a hydraulic actuator. The mechanical devices may be balancing mechanisms having a pivotable linking lever () by which the roller carrier () of the first cavity and the roller carrier () of the second cavity are linked.

Dual-cavity toroidal variator

In a toroidal variator a plurality of rolling elements () are in driving engagement with an input and output race () at respective contact regions. Each rolling element () is mounted on a carriage assembly () for rotation about a rolling axis, and is being free to pivot about a tilt axis, the tilt axis passing through the rolling element () perpendicular to the rolling axis, and intersecting the rolling axis at a roller center, whereby a change in the tilt axis causes a change in the variator ratio being the ratio of rotational speeds of the races. The tilt axis is arranged at an angle known as castor angle (see FIG.) to a plane (P) perpendicular to the variator axis (V). Each carriage assembly () can cause a movement of the rolling element () with a component of rotation about a pitch axis (A, B). The pitch axis is defined as passing through the roller center and through the contact regions. Pitching the roller elements () causes them to tilt, thereby changing the transmission ratio.

Continuously variable toroidal transmission

A variator transmission comprises an input shaft (), an input disc () mounted on the input shaft for rotation therewith and an output disc () facing the input disc and arranged to rotate coaxially therewith, the input and output discs defining between them a toroidal cavity. Two rollers () are located in the toroidal cavity and first and second roller carriage means are provided upon which the first and second rollers respectively are rotatably mounted and end load means () urge the rollers into contact with the input and output discs to transmit drive. The two roller carriage means are mounted on opposite sides of the pivotal axis of a lever () and the pivotal axis of the lever () is movable in both the radial and non-radial directions with respect to the rotational axis of the input and output discs.

Drive mechanism for infinitely variable transmission

A variator transmission comprises an input shaft (), an input disc () mounted on the input shaft for rotation therewith and an output disc () facing the input disc and arranged to rotate coaxially therewith, the input and output discs defining between them a toroidal cavity. Two rollers () are located in the toroidal cavity and first and second roller carriage means are provided upon which the first and second rollers respectively are rotatably mounted and end load means () urge the rollers into contact with the input and output discs to transmit drive. The two roller carriage means are mounted on opposite sides of the pivotal axis of a lever () and the pivotal axis of the lever () is movable in the radial direction with respect to the rotational axis of the input and output discs.

A roller control unit for a CVT includes a cylinder (,) having a piston (,) positioned therein and operably connected to a roller assembly of said CVT thereby to control its position. The unit includes a lubrication supply which comprises a chamber (,) between the cylinder (,) and piston (,) and one or more radially extending passageways (,) through said piston (,). These passageways are in flow communication with the roller and act to direct cooling fluid to said roller. Radial supply of said lubrication facilitates a reduction in flow losses within the supply.

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Wigan, United Kingdom

Andrew Damian De Freitas