Skip-cycle strategies for four cycle engine
First Claim
1. In an automotive type four cycle multicylinder engine having intake and exhaust valves for each and every cylinder, the improvement comprising valve control means including means for operating the engine in a variety of skip cycle strategies by deactivating, in inverse proportion to the change in the load level, one or more of the cylinders during engine operation, the means further including means for converting the stroke of the piston of a deactivated cylinder from its set stroke in the four cycles of engine operation to an earlier stroke in the cycle to assure the sequential firing of each of the cylinders all within a predetermined limited number of revolutions of the engine crankshaft defined by one complete skip cycle sequence for the particular load level.
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Accused Products
Abstract
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.
273 Citations
7 Claims
- 1. In an automotive type four cycle multicylinder engine having intake and exhaust valves for each and every cylinder, the improvement comprising valve control means including means for operating the engine in a variety of skip cycle strategies by deactivating, in inverse proportion to the change in the load level, one or more of the cylinders during engine operation, the means further including means for converting the stroke of the piston of a deactivated cylinder from its set stroke in the four cycles of engine operation to an earlier stroke in the cycle to assure the sequential firing of each of the cylinders all within a predetermined limited number of revolutions of the engine crankshaft defined by one complete skip cycle sequence for the particular load level.
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3. In an automotive type four cycle multicylinder engine, a camless, electrohydraulic valvetrain with valve control means for selectively and individually opening and closing each of the intake and exhaust valves for each and every cylinder, the valve control means comprising means promoting operating the engine in an unthrottled manner by a variety of skip cycle strategies by deactivating in inverse proportion to the change in the load level one or more of the cylinders during engine operation while assuring sequential firing of the one or more, as well as the remaining, cylinders totally within a predetermined controlled number of revolutions of the engine crankshaft varying as a function of the load, said latter means including the valve control means for maintaining closed the intake and exhaust valves of each of the one or more cylinders being deactivated, thereby eliminating the intake of air and the exhaust of gases thereby eliminating pumping and reducing compression losses, the selective control of the opening and closing of the intake and exhaust valves permitting the selective changing of the cylinders firing order by converting the stroke of the piston of the cylinder in a selective manner from intake to expansion or compression to exhaust to assure firing in an earlier cycle than its normal sequence of the deactivated cylinder upon reactivation to thereby assure firing of all of the cylinders within the predetermined number of revolutions.
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4. A method of operating an automotive type four cycle engine in the skip cycle manner including the steps of:
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deactivating the supply of fuel to one or more cylinders to be deactivated; in succession, closing and maintaining closed the intake and exhaust valves of the cylinders to be deactivated; and reactivating and firing each of the one or more deactivated engine cylinders in an earlier cycle than its normal sequence and within one complete skip cycle sequence for the particular load level has occurred to minimize cooldown of cylinders previously deactivated. - View Dependent Claims (5, 6, 7)
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Specification