Ford Global Technolgoies, LLC

Matthew Scott Malnar

Scott Joseph Gittins

Derek Kinch

Samuel Melville Glauber

Timothy Fedullo

Alexander Phillip McDonnell

Joseph Scott Slayton

Lisa Waldock

Allison Lynch

A park valve performs a multi-plexing function in which an out-of-park circuit is connected to line pressure when the valve is in an out-of-park position and is vented when the valve is in a park position. When particular clutches are released, the out-of-park circuit biases the park valve toward the out-of-park position. To initiate engagement of park, a controller commands a low line pressure, reducing the forces that bias the park valve toward the out-of-park position. Once the valve reaches an intermediate position in which the line pressure circuit is no longer fluidly connected to the out-of-park circuit, the controller commands an increase in line pressure, increasing the forces that bias the park valve toward the park position.

Transmission park control system

A park valve includes a slidable end-cap. Under normal circumstances, the end-cap is held in a nominal position by a spring, such as a Belleville spring. The park valve performs a multi-plexing function in which an out-of-park circuit is connected to line pressure when the valve is in an out-of-park position and is vented when the valve is in a park position. In an intermediate position, a hydraulic lock condition may potentially occur. When engaging park, the hydraulic lock condition is prevented by the slidable end-cap.

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Matthew Scott Malnar