Line pressure control for a continuously variable transmission
AssigneeGeneral Motors Corporation
InventorsTodd Roy Berger, Steven Patrick Moorman, Brian W. Whitmarsh
Life of this patent
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Abstract
An electro-hydraulic control for a continuously variable transmission includes a first regulator valve which is controlled to provide a high pressure output to control the ratio within the continuously variable transmission and a second regulator valve which is controlled to provide an engagement pressure for torque transmitting mechanisms within the transmission. The control incorporates multiplexing of the valve components, creates prioritization of fluid flow, detection of priority mode of operation, over-pressurization protection valves, and ensures a minimum of fluid flow to the torque transmitting mechanisms and the oil cooler.
Claims3
An electro-hydraulic control in a transmission having a continuously variable unit requiring a first pressure level and at least one friction device requiring a second pressure level, said electro-hydraulic control comprising:
- a source of fluid pressure;
- a first pressure regulator valve in fluid communication with said source of fluid pressure to limit the pressure of said source to a first predetermined level;
- a second pressure regulator valve in downstream fluid flow relation with said first pressure regulator valve and having a fluid output pressure limited at a second predetermined level at a value less than said first predetermined level;
- and
- a variable pressure control valve means in fluid communication with said source and having a variable output pressure communicated with both said first and second pressure regulator valves for providing a control pressure thereto to establish said first and second predetermined levels.
Dependencies are inferred from the claim text.