Engine operating method and apparatus
View Patent ↗An internal combustion engine includes a plurality of cylinders each having intake and exhaust valves and at least one camshaft timed to operate the valves with a high performance fixed overlap. Each camshaft has a cam phaser controlled to equally vary the intake and exhaust valve timing for superior full throttle performance over the engine speed range; Valve deactivation mechanisms operate to deactivate up to half the cylinders during idle and light load operation for increasing fuel efficiency and emission control and maintaining stable operation of the operating cylinders. The engine may also be started with half the cylinders cut out and then run with stable operation in this mode during idle and light load because the increased load on the operating cylinders gives stable operation with an increased valve overlap permitting increased performance and emission control at higher load operation on all the cylinders.
1. A method for obtaining high performance and reduced emissions from an engine, the method comprising:
providing a high fixed intake and exhaust valve overlap selected to obtain high wide open throttle performance over the engine speed range, and reduced fuel consumption and NOx emissions through increased trapped exhaust residuals in part load operation;
equally varying the intake and exhaust valve timing to obtain superior full throttle performance over the speed range; and
deactivating operation of up to half of the engine cylinders during idle and low speed/load operation to provide increased load of the operating cylinders with resulting improved fuel efficiency and lower HC emissions.
2. A method as in claim 1 including starting the engine during deactivation of up to half of the cylinders.
3. An internal combustion engine comprising in combination:
a plurality of cylinders each having intake and exhaust valves and at least one camshaft timed to operate the valves with a high performance fixed overlap;
a cam phaser for each camshaft and controlled to equally vary the intake and exhaust valve timing for superior full throttle performance over the engine speed range; and
valve deactivation mechanism for up to half the cylinders and operative to deactivate the associated cylinders during idle and light load operation for increasing fuel efficiency and emission control and maintaining stable operation of the operating cylinders.
4. An engine as in claim 3 wherein the valve deactivation mechanism is operative during starting of the engine.
5. An engine as in claim 3 wherein the valves are actuated by at least one camshaft and each camshaft is controlled by a cam phaser operative to vary equally the timing of both intake and exhaust valves.
6. An engine as in claim 5 wherein a single camshaft actuates all intake and exhaust valves and the camshaft timing is controlled by a single cam phaser.