Transmission park control system
AssigneeFord Global Technologies, LLC
InventorsDerek Kinch, Timothy Andrew Sikowski
Life of this patent
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Abstract
A transmission includes a hydraulically actuated park valve with two spools in a common housing. One of the spools engages and disengages the park mechanism in response to manipulation of line pressure and engagement of specified shift elements. A pin selectively engages this spool to hold it in position. The valve is designed such that friction holds the spool in position in the absence of hydraulic pressure or electric power. The second spool controls an out-of-park circuit such that the park mechanism remains disengaged when desired. The two spools are separated by a compression spring.
Claims12
A transmission comprising:
- a first spool supported to slide within a valve housing between first and second positions, the first spool configured to disengage a park mechanism in the first position and to engage the park mechanism in the second position;
- a line pressure circuit configured to bias the first spool toward the second position;
- a second spool supported to slide within the valve housing between third and fourth positions, the second spool configured to fluidly connect an out-of-park hydraulic circuit to the line pressure circuit in the third position and to vent the out-of-park circuit in the fourth position;
- first and second hydraulic circuits configured to bias the second spool toward the third position;
- a compression spring configured to separate the first spool from the second spool, biasing the first spool toward the first position and biasing the second spool toward fourth position;
- a pin configured to selectively engage the first spool to restrict motion of the first spool;
- and
- a solenoid configured to pull the pin away from the first spool.
A park valve comprising:
- first and second spools supported to slide within a valve housing, the first spool adapted to mechanically engage and disengage a park mechanism;
- a compression spring configured to separate the first spool from the second spool;
- a pin configured to selectively engage the first spool to restrict motion of the first spool;
- and
- a solenoid configured to pull the pin away from the first spool.
Dependencies are inferred from the claim text.