Gm Global Technolgoy Operations, Inc.

Roger Hanggi

Ananth Krishnan

A method is provided for controlling an output/input speed ratio of a continuously variable transmission (CVT) plant including primary and secondary pulleys actuated by primary and secondary pressures (P ,P ,), respectively, which generate forces to move the pulleys and adjust a corresponding belt, thereby adjusting the output/input ratio. The method includes calculating a desired force ratio for the CVT plant. Desired primary and secondary pressures (P ,P ) are then determined based, in part, upon the calculated desired force ratio, and the desired P and P signals are sent to the CVT plant to control operation of the CVT plant. An actual speed ratio is calculated based on measurements of input and output speed from the CVT plant. An error signal is generated based upon the measured actual speed ratio for use in calculating a next sample time desired force ratio which is then used to calculate desired P and P signals to be sent as inputs to the CVT plant, thereby using the desired force ratio as the controlled variable in controlling the output/input speed ratio of the CVT plant.

Method of controlling a CVT speed ratio

A variable displacement vane pump comprises a pump body having inlet and outlet ports, a rotor driven by a drive shaft and co-axially aligned therewith, a plurality of radially extending vanes slidably disposed in the rotor, and a slide pivotally disposed on a pivot in the pump body and having a central axis eccentric to the axis of the rotor. A plurality of fluid chambers are defined by the rotor, vanes, and slide. A spring acts on the slide to urge the slide in one direction. A regulating chamber is configured as a semi-circular cylinder intermediate the pump body and an outer surface of the slide, wherein a pressure regulating valve pressurizes the regulating chamber to pivot the slide against the force of the spring to decrease the volume of the fluid chambers. The slide includes a slide channel formed in a face to channel fluid leakage from the fluid chambers away from the regulating chamber.

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Saline, MI, United States of America

Roger Hanggi