Control system for variable displacement engine

Claim 1

In an internal combustion engine including a plurality of cylinders each of which includes intake and exhaust valves and an associated valve deactuator whose operation controls operation of the associated intake and exhaust valves and thereby also affects engine intake manifold vacuum, a control system for the valve deactuators comprising: a sensor for sensing intake manifold vacuum of the engine; a control unit for operating the engine valve deactuators with a hysteretic action in response to the vacuum sensed by the sensor so as to prevent oscillatory on-off operation of the valve deactuators; the control unit including electrical switches for providing an electrical signal that operates the valve deactuators; the control unit also including a switch operator for operating the switches in response to the vacuum sensed by the sensor; the switch operator including a lost motion connection for providing the hysteretic action that prevents oscillatory on-off operation of the valve deactuators; the switch operator also including a rod movable in response to the vacuum sensed and a switch operating member that is mounted by the lost motion connection on the rod so as to operate the switches in a sequential manner as the vacuum increases; the rod including stops for moving the switch operating member; a retarder for preventing movement of the operating member with the rod prior to engagement thereof by one of the stops; and wherein the retarder comprises a spring that frictionally engages the switch operating member.