Patent ID: 8020527
Filing Date: 2011-09-20
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 of the valve by an amount of change corresponding to a rotational speed of an electric motor that is used as an actuator relative to a rotational speed of a camshaft that drives the valve; a first sensor that detects the rotational speed of the camshaft; a second sensor that detects the rotational speed of the electric motor; a first controller that calculates a current value of the opening/closing timing of the valve based on at least a signal from the first sensor and a signal from the second sensor, and that prepares a rotational speed command value for the electric motor based on a deviation of the current value of the opening/closing timing from a target value of the opening/closing timing, which is set based on an operating state of the engine, such that the opening/closing timing changes in accordance with the target value; and a second controller that receives a signal indicating the rotational speed command value from the first controller, and controls an electric power supply to the electric motor based on the rotational speed of the electric motor, which is detected by the second sensor, such that the electric motor operates in accordance with the rotational speed command value; wherein the second controller controls the rotational speed of the electric motor by executing, in combination, a setting control based on the rotational speed command value set by the first controller and a feedback control based on a deviation of the actual rotational speed of the electric motor from the rotational speed command value.