Valve control system for internal combustion engine

Claim 1

A control system for controlling intake and exhaust valves of an internal combustion engine, said valves each being constructed of a ceramic material and each having a valve body and an elongated valve stem, said stem having one end attached to said body and a distal end spaced from said body, said system comprising: electromagnetic actuator means for opening and closing the intake and exhaust valves, said actuator means comprising an actuator for each valve, each actuator comprising a magnetic member mounted on the corresponding valve stem and first and second electromagnets, said electromagnets being spaced apart longitudinally of said stem and disposed on respective opposite sides of the magnetic member; an engine speed sensor for detecting the rotational speed of the internal combustion engine; a crankshaft angle sensor for detecting the angular position of the crankshaft of the internal combustion engine; timing calculating means for calculating the timing at which the intake and exhaust valves are to be opened and closed, based on a detected signal from said crankshaft angle sensor; calculating means for calculating the angular positions at which the intake and exhaust valves are to be opened and closed with respect to the crankshaft angle, based on detected signals from said engine speed sensor and said crankshaft angle sensor, said calculating means including means for reducing the duration of the period during which the intake and exhaust valves are open when the rotational speed of the internal combustion engine is lower and for increasing the duration of the period during which the intake and exhaust valves are open when the rotational speed of the internal combustion engine is higher; and control means for applying drive signals to said electromagnetic actuator means in response to the calculated angular position, said control means comprising operating means for each valve for selectively energizing one of the electromagnets to open the corresponding valve, deenergizing said one electromagnet and energizing the other electromagnet to close said corresponding valve when the crank shaft reaches a first predetermined angular position, and deenergizing said other electromagnet and energizing said one electromagnet to open said corresponding valve when the crank shaft reaches a second predetermined angular position.