| 摘要 |
Strategies for operating a four cycle engine in skip-cycle manner include providing the engine with a valve control so that each intake and exhaust valve for each cylinder can be individually activated or deactivated essentially instantaneously to provide a skip-cycle pattern that varies as a function of the load. Individual of the valves permits changing the purpose of the stroke off each piston of each deactivated cylinder from compression to exhaust or intake to expansion, as the case may be, to assure firing of all of the engine cylinders within as short a period as one skip cycle to prevent cylinder cooldown, which promotes emissions. Unthrottled operation also is provided by closing the intake and exhaust valves in a particular sequence during skip cycle operation, and controlling the intake valve closure timing during load periods between skip cycle periods to continue unthrottled operation for all load levels. Further individual activation or deactivation of the fuel injectors and spark plugs enhances the skip cycle, unthrottled operation.
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