Patent ID: 6883475
Filing Date: 2005-04-26
Classification: F01L,Y10T

Abstract:
1. A variable cam timing system for an internal combustion engine having a crankshaft, at least one camshaft, a cam drive connected to the crankshaft, and a variable cam phaser having an inner portion mounted to at least one camshaft and a concentric outer portion connected to the cam drive, the relative angular positions of the inner portion and the outer portion being controllable in response to a fluid control input, such that the relative phase of the crankshaft and at least one camshaft can be shifted by varying the fluid at the fluid control input of the variable cam phaser, the variable cam timing system comprising: a) a spool valve ( b) an internal differential pressure control system comprising a solenoid valve ( wherein an electrical signal at the electrical input causes a change in the pressure output being fed to the second spool end, causing the spool to move axially in the bore.