Patent ID: 6772718
Filing Date: 2004-08-10
Classification: F01L

Abstract:
A valve system for controlling flow of gas into or out of a variable volume chamber of an internal combustion engine or a compressor, the valve system comprising:a gas flow control valve which opens to permit flow of gas into or out of the variable volume chamber; a hydraulic actuator connected to the gas flow control valve; a pump for pressurizing hydraulic fluid; a reservoir of hydraulic fluid; and a control system which controls opening and closing of the gas control valve by controlling flow of hydraulic fluid to the hydraulic actuator from the pump and flow of hydraulic fluid from the hydraulic actuator to the reservoir, the control system comprising: an electrically controlled flow direction control valve which controls direction of flow of hydraulic fluid to the actuator to control whether the hydraulic actuator opens or closes the gas flow control valve; and an electrically controlled switching valve which controls whether or not any hydraulic fluid flows to the hydraulic actuator and thereby controls the time of opening and closing of the gas flow control valve; and wherein: the pump is an electrically controlled variable flow rate pump which controls the rate of opening or closing of the gas flow control valve by controlling the rate of flow of hydraulic fluid to the hydraulic actuator; and operation of the pump, the flow direction control valve and the switching valve is controlled by an electronic controller.