Patent ID: 7958858
Filing Date: 2011-06-14
Classification: F01L,F02D,Y02T

Abstract:
1. A variable valve timing system that changes opening/closing timing of at least one of an intake valve and an exhaust valve provided in an engine, comprising: a changing mechanism that changes the opening/closing timing by changing a rotational phase difference between a camshaft, which drives the valve of which the opening/closing timing is changed, and a crankshaft by an amount of change corresponding to an operation amount of an actuator, when the engine is operating, wherein the changing mechanism sets a ratio of the amount of change in the opening/closing timing with respect to the operation amount of the actuator to a lower value when the opening/closing timing is within a first phase region than when the opening/closing timing is within a second phase region; a target phase setting unit that sets target opening/closing timing of at least one of the intake valve and the exhaust valve based on an operating state of the engine; a phase control unit that sets the operation amount of the actuator based on a result of comparison between the target opening/closing timing and the actual opening/closing timing; and a target phase restriction unit that restricts the target opening/closing timing used when the engine is operating such that the opening/closing timing is within the first phase region when the engine is stopped due to the operation of the actuator after a command to stop the engine is issued.