Multi-level skip fire
First Claim
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1. A method of controlling the operation of an internal combustion engine having a plurality of working chambers to deliver a desired output, wherein each working chamber has at least one intake valve that is cam-actuated and at least one exhaust valve, the method comprising:
- operating the engine in a dynamic firing level modulation mode that causes selected low working cycles to be fired at a low torque output and selected high working cycles to be fired at a high torque output, wherein decisions whether to fire each working cycle at a high or low torque output are dynamically determined during operation of the engine on a firing opportunity by firing opportunity basis; and
adjusting an air charge for each fired working cycle based on whether the high or low torque output was selected for such fired working cycle.
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Abstract
In one aspect, a method for controlling operation of an internal combustion engine is described. The engine is operated in a skip fire manner such that selected skipped working cycles are skipped and selected active working cycles are fired to deliver a desired engine output. A particular level of torque output is selected for each of the fired working chambers. Various methods, arrangements and systems related to the above method are also described.
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Citations
24 Claims
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1. A method of controlling the operation of an internal combustion engine having a plurality of working chambers to deliver a desired output, wherein each working chamber has at least one intake valve that is cam-actuated and at least one exhaust valve, the method comprising:
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operating the engine in a dynamic firing level modulation mode that causes selected low working cycles to be fired at a low torque output and selected high working cycles to be fired at a high torque output, wherein decisions whether to fire each working cycle at a high or low torque output are dynamically determined during operation of the engine on a firing opportunity by firing opportunity basis; and adjusting an air charge for each fired working cycle based on whether the high or low torque output was selected for such fired working cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of controlling the operation of an internal combustion engine having a plurality of working chambers to deliver a desired output, wherein each working chamber has at least one intake valve that is cam-actuated and at least one exhaust valve, the method comprising:
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operating the engine in a dynamic firing level modulation mode that causes selected low working cycles to be fired at a low torque output and selected high working cycles to be fired at a high torque output; determining a desired effective firing fraction indicative of a fraction of the firing opportunities that would need to be fired at a reference output level to deliver the desired output; and determining which working cycles are to be fired at a high output and which working cycles are to be fired at a low output based at least in part on the effective firing fraction, wherein decisions whether to fire each working cycle at a high or low torque output are dynamically determined during operation of the engine on a firing opportunity by firing opportunity basis; and adjusting an air charge for each fired working cycle based on whether the high or low torque output was selected for such fired working cycle. - View Dependent Claims (12, 13, 14)
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15. A method of controlling the operation of an internal combustion engine having a plurality of working chambers to deliver a desired output, wherein each working chamber includes a first intake valve, a second intake valve, and at least one exhaust valve, the first and second intake valves being cam actuated, the method comprising:
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operating the engine in a dynamic firing level modulation mode that causes selected low working cycles to be fired at a low torque output and selected high working cycles to be fired at a high torque output, wherein decisions whether to fire each working cycle at a high or low torque output are dynamically determined during operation of the engine on a firing opportunity by firing opportunity basis; and adjusting an air charge for each fired working cycle based on whether the high or low torque output was selected for such fired working cycle, wherein when a working cycle is fired at a high torque output, the first and second intake valves of the associated working chamber are independently controlled based on a high torque valve control scheme, and when a working cycle is fired at a low torque output, the first and second intake valves of the fired working chamber are independently controlled based on a low torque valve control scheme, which is different from the high torque valve control scheme. - View Dependent Claims (16, 17)
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18. A method of controlling the operation of an internal combustion engine having a plurality of working chambers to deliver a desired output, wherein each working chamber has at least one intake valve that is cam-actuated and at least one exhaust valve, the method comprising:
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operating the engine in a dynamic firing level modulation mode that causes selected low working cycles to be fired at a low torque output and selected high working cycles to be fired at a high torque output, wherein decisions whether to fire each working cycle at a high or low torque output are dynamically determined during operation of the engine on a firing opportunity by firing opportunity basis; and adjusting an air charge for each fired working cycle based on whether the high or low torque output was selected for such fired working cycle, and wherein working cycles fired at the low torque output are firing in a condition that substantially provides a minimum brake specific fuel consumption for such working cycles.
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19. A firing controller for use in controlling the operation of an internal combustion engine having a plurality of working chambers to deliver a desired output, wherein each working chamber has at least one intake valve that is cam-actuated and at least one exhaust valve, the firing controller comprising:
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a firing level determining unit that identifies selected low working cycles to be fired at a low torque output and selected high working cycles to be fired at a high torque output, the firing level determining unit being arranged to make the high or low torque output determinations on a firing opportunity by firing opportunity basis during operation of the engine; and a firing control unit arranged to direct operation of cam operated valves in a manner that provides a lower air charge for low torque output working cycles than is provided for high air charge working cycles. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification