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US 6,668,778 B1Granted
Using differential pressure control system for VCT lock
AssigneeBorgWarner Inc.
InventorFranklin R. Smith
Life of this patent
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Abstract
A variable cam timing system comprising a VCT locking pin in hydraulic communication with the control circuit of the differential pressure control system (DPCS) is provided. When the control pressure is less than 50% duty cycle the same control signal commands the locking pin to engage and the VCT to move toward the mechanical stop. When the control pressure is greater than 50% duty cycle the locking pin disengages and the VCT moves away from the mechanical stop.
Claims5
A variable cam timing (VCT) phaser control system for a phaser, comprising:
- a spool valve disposed to be spring loaded to a null position from fluid pressures at a first end and a second end, the first end being subject to a control fluid and the second end having an area being subject to source fluid;
- a piston engaging a first end of the spool valve, the piston having an opposite side having an area substantially greater than the area of the second end being subject to source fluid;
- a locking pin locking the phaser at a fixed angular position, thereby controlling the locking pin free of additional control means;
- and
- a controller in fluid communication with both the piston and the locking pin for controlling the control fluid characteristics.
2 more elements
Dependencies are inferred from the claim text.