Allison Transmission, Inc.

Torotrak (development) Limited

John Fuller

Brian Joseph Dutson

Andrew Damian De Freitas

James Shawe

David Burtt

Michael Holmes

Andrew Defreitas

A variator for a mechanical transmission system is disclosed. Transfer means are in rolling contact with input and output members of the variator to transfer rotary motion between them. The input member is coupled to the variator input through a first biasing device arranged to exert a first biasing force on the variator according to a first, input gain which relates input torque acting on the input member and the first biasing force. The output member is coupled to the variator output through a second biasing device arranged to exert a second biasing force on the variator according to a second, output gain which relates output torque acting on the output member and the second biasing force. The first and second biasing forces clamp the variator to provide traction. The first, input gain and second, output gain are different, which, at least in specific variator applications, optimises the traction coefficient.

Variators

A variator comprises first and second races disposed for rotation about a variator axis and at least one rolling element disposed in a cavity between the races. In a drive configuration, drive is transmitted between the races and the at least one rolling element; and in a neutral configuration, the at least one rolling element and races are configured whereby the races can move independently of one another. In a method of operating the variator, the neutral configuration is obtained by moving the at least one rolling element to a position in which it ceases to make contact with at least one of the races. The drive configuration is obtained by moving the at least one rolling element to a position in which it makes contact with both of the races.

Variator

A supercharging arrangement for an internal combustion engine. The supercharging arrangement comprises a supercharger having a rotational drive input, and a transmission having a rotational drive input to receive drive from an internal combustion engine, and a rotational drive output connected to the input of the supercharger. The transmission includes a variator operatively connected between the input and the output of the transmission, which variator has an output that is driven at an operating ratio from an input. A control system operates to cause an engine to deliver an amount of torque that is indicated by the state of an input to the control system. The control system is further operative to set the operating ratio of the variator.

Drive arrangement for an engine ancillary such as a supercharger

A supercharging arrangement for an internal combustion engine is disclosed. The supercharging arrangement comprises a supercharger having a rotational drive input, and a transmission having a rotational drive input to receive drive from an internal combustion engine, and a rotational drive output connected to the input of the supercharger. The transmission includes a variator operatively connected between the input and the output of the transmission, which variator has an output that is driven at an operating ratio from an input. There is a control system that operates to cause an engine to deliver an amount of torque that is indicated by the state of an input to the control system. The control system is further operative to set the operating ratio of the variator.

Supercharging arrangement with a supercharger and variable-speed drive unit

In a continuously-variable-ratio-device of the type having races between which drive is transferred by rollers which are movable in accordance with changes of variator ratio, it is necessary to apply a traction load urging the rollers and races into engagement. Each rollers is also subject to a transverse reaction force by a hydraulic reaction roller actuator receiving a controlled reaction pressure. It is desirable to create a relationship between traction and reaction force, and also to provide for adjustment of this relationship. In the present invention this is achieved hydraulically. A traction pressure related to the reaction pressure is applied to an actuator which creates the traction load. The hydraulics also include a working chamber, which is selectively connectable to and disconnectable from either (or both) of (i) the reaction pressure and (ii) the traction pressure, the traction force being dependent upon pressure in the working chamber.

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Lancashire, United Kingdom

John Fuller