Method of and apparatus for controlling valve operation in an internal combustion engine

Claim 1

A method of controlling valve operation in an internal combustion engine having a crankshaft for driving a camshaft with a cam for opening and closing an intake or exhaust valve which is spring-biased in a closing direction, said method comprising the steps of, varying the angular phase of the crankshaft and the camshaft dependent on operating conditions of the engine to control the timing of opening the intake or exhaust valve, and releasing a force applied by the cam to open the intake or exhaust valve while the intake or exhaust valve is being opened to control the timing of closing the intake or exhaust valve.

Claim 2

A method of controlling valve operation in an internal combustion engine having a crankshaft for driving a camshaft with a cam for opening and closing an intake or exhaust valve which is spring-biased in a closing direction, said method comprising the steps of, varying the angular phase of the crankshaft and the camshaft dependent on operating conditions of the engine to control the timing of opening the intake or exhaust valve, and releasing a force applied by the cam to open the intake or exhaust valve while the intake or exhaust valve is being opened to control the timing of closing the intake or exhaust valve.

Claim 8

An apparatus for controlling valve operation in an internal combustion engine having a crankshaft for driving a camshaft with a cam for opening and closing an intake or exhaust valve which is spring-biased in a closing direction, said apparatus comprising, phase control means disposed between the crankshaft and the camshaft and lift control means disposed between the cam and the intake or exhaust valve, said phase control means including hydraulic means for changing the angular relationship between the camshaft and a timing wheel driven by the crankshaft for driving the camshaft, means for controlling said hydraulic means in response to engine operating conditions, said lift control means including hydraulic piston means for transmitting a valve-opening force from the cam to the valve, and hydraulic valve means for selectively releasing the valve-opening force in response to engine operating conditions.

Claim 9

An apparatus for controlling valve operation in an internal combustion engine having a crankshaft for driving a camshaft with a cam for opening and closing an intake or exhaust valve which is spring-biased in a closing direction, said apparatus comprising, phase control means disposed between the crankshaft and the camshaft and lift control means disposed between the cam and the intake or exhaust valve, said phase control means including hydraulic means for changing the angular relationship between the camshaft and a timing wheel driven by the crankshaft for driving the camshaft, means for controlling said hydraulic means in response to engine operating conditions, said lift control means including hydraulic piston means for transmitting a valve-opening force from the cam to the valve, and hydraulic valve means for selectively releasing the valve-opening force in response to engine operating conditions.

Claim 15

An apparatus for controlling valve operation in an internal combustion engine having a crankshaft for driving a camshaft with a cam for opening and closing an intake or exhaust valve which is spring-biased in a closing direction, said apparatus comprising, phase control means disposed between the crankshaft and the camshaft and lift control means disposed between the cam and the intake or exhaust valve, said phase control means comprising a rotatable shaft coupled to the camshaft, a timing wheel drivable by the crankshaft and disposed coaxially with the rotatable shaft for angular movement relative thereto, a piston having one axial end facing into a hydraulic pressure chamber and normally spring-biased in one axial direction, said piston being coaxial with said rotatable shaft and said timing wheel, a coupling mechanism for operatively coupling said piston, said timing wheel, and said rotatable shaft to vary the angular phase of said timing wheel and said rotatable shaft dependent on axial movement of said piston, and a servovalve for cutting off the communication between the hydraulic pressure chamber and either a hydraulic pressure supply passage or a hydraulic pressure release passage in response to axial movement of said piston according to an amount of operation of an actuating member, said lift control means comprising a cam piston having one end operatively coupled to said cam, a working oil chamber in which the other end of said cam piston is disposed and which is held in communication with a hydraulic pressure source, a valve piston operatively coupled to the intake or exhaust valve for opening the intake or exhaust valve under hydraulic pressure from said working oil chamber, and a hydraulic pressure release valve connected to said working oil chamber for relieving the hydraulic pressure from said working oil chamber while the intake or exhaust valve is being opened.

Claim 16

An apparatus for controlling valve operation in an internal combustion engine having a crankshaft for driving a camshaft with a cam for opening and closing an intake or exhaust valve which is spring-biased in a closing direction, said apparatus comprising, phase control means disposed between the crankshaft and the camshaft and lift control means disposed between the cam and the intake or exhaust valve, said phase control means comprising a rotatable shaft coupled to the camshaft, a timing wheel drivable by the crankshaft and disposed coaxially with the rotatable shaft for angular movement relative thereto, a piston having one axial end facing into a hydraulic pressure chamber and normally spring-biased in one axial direction, said piston being coaxial with said rotatable shaft and said timing wheel, a coupling mechanism for operatively coupling said piston, said timing wheel, and said rotatable shaft to vary the angular phase of said timing wheel and said rotatable shaft dependent on axial movement of said piston, and a servovalve for cutting off the communication between the hydraulic pressure chamber and either a hydraulic pressure supply passage or a hydraulic pressure release passage in response to axial movement of said piston according to an amount of operation of an actuating member, said lift control means comprising a cam piston having one end operatively coupled to said cam, a working oil chamber in which the other end of said cam piston is disposed and which is held in communication with a hydraulic pressure source, a valve piston operatively coupled to the intake or exhaust valve for opening the intake or exhaust valve under hydraulic pressure from said working oil chamber, and a hydraulic pressure release valve connected to said working oil chamber for relieving the hydraulic pressure from said working oil chamber while the intake or exhaust valve is being opened.