Using differential pressure control system for VCT lock 

Patent No. 6,668,778

Issued: December 30, 2003
Filed: March 19, 2003

Inventor: Smith; Franklin R. (Cortland, NY)
Assignee: BorgWarner Inc. (Auburn Hills, MI)

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.