CONTROL OF MANIFOLD VACUUM IN SKIP FIRE OPERATION
First Claim
1. A method of selectively reducing intake manifold pressure in a skip fire engine control system to help purge a fuel vapor canister, reduce pressure within a brake vacuum booster reservoir or vent gas from a crankcase interior, the method comprising:
- operating an engine in a skip fire manner to generate a desired torque level using a throttle set at a substantially open position;
further closing the throttle to reduce the intake manifold pressure in order to perform a manifold vacuum-related process selected from the group consisting of
1) purging the fuel vapor canister;
2) reducing pressure within a brake vacuum booster reservoir; and
3) venting gas from the crankcase interior;
increasing an engine firing fraction to help maintain the desired torque level; and
after the manifold vacuum-related process has been performed, returning the throttle to the substantially open position and decreasing the firing fraction.
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Accused Products
Abstract
A variety of methods and arrangements are described for selectively reducing intake manifold pressure in a skip fire engine control system. In some embodiments, a throttle is adjusted to generate a manifold vacuum, which is used for various applications, including but not limited to purging a fuel vapor canister, reducing pressure within a brake vacuum booster reservoir and/or venting gas from a crankcase interior. An engine firing fraction is increased to help maintain a desired torque level. Other techniques for reducing the intake manifold pressure are also described, such as applications involving a return to idle.
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Citations
20 Claims
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1. A method of selectively reducing intake manifold pressure in a skip fire engine control system to help purge a fuel vapor canister, reduce pressure within a brake vacuum booster reservoir or vent gas from a crankcase interior, the method comprising:
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operating an engine in a skip fire manner to generate a desired torque level using a throttle set at a substantially open position; further closing the throttle to reduce the intake manifold pressure in order to perform a manifold vacuum-related process selected from the group consisting of
1) purging the fuel vapor canister;
2) reducing pressure within a brake vacuum booster reservoir; and
3) venting gas from the crankcase interior;increasing an engine firing fraction to help maintain the desired torque level; and after the manifold vacuum-related process has been performed, returning the throttle to the substantially open position and decreasing the firing fraction. - View Dependent Claims (2, 3, 4, 5)
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6. A method of selectively reducing intake manifold pressure in a skip fire engine control system to prepare for a return to idle, the method comprising:
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operating an engine of a vehicle in a skip fire manner to generate a desired torque level using a throttle set at a substantially open position; detecting that the engine will return to idle; closing the throttle to help reduce the intake manifold pressure; increasing an engine firing fraction to help reduce the intake manifold pressure; and adjusting an engine parameter to help maintain the desired torque level. - View Dependent Claims (7, 8, 9, 10)
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11. An engine controller used to control an internal combustion engine, the engine controller comprising:
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a power train parameter adjusting module that is arranged to; set the throttle at a substantially open position to help deliver a desired torque level; further close the throttle to reduce the intake manifold pressure in order to perform a manifold vacuum-related process selected from the group consisting of
1) purging the fuel vapor canister;
2) reducing pressure within a brake vacuum booster reservoir;
3) venting gas from the crankcase interior; and
4) preparing for a return to idle; andreturn the throttle to the substantially open position after the manifold vacuum-related process has been at least substantially completed; and a firing fraction calculator that is arranged to; generate a firing fraction that is used to operate working chambers of the engine in a skip fire manner and that helps deliver the desired torque level; and adjust the firing fraction in order to help perform the manifold vacuum-related process. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A computer readable storage medium that includes executable computer code embodied in a tangible form operable to selectively reduce intake manifold pressure in a skip fire engine control system wherein the computer readable medium includes:
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executable computer code for setting the throttle at a substantially open position to help deliver a desired torque level; executable computer code for further closing the throttle to reduce the intake manifold pressure in order to perform a manifold vacuum-related process selected from the group consisting of
1) purging the fuel vapor canister;
2) reducing pressure within a brake vacuum booster reservoir;
3) venting gas from the crankcase interior; and
4) preparing for a return to idle;executable computer code for returning the throttle to the substantially open position after the manifold vacuum-related process has been at least substantially completed; and executable computer code for generating a firing fraction that is used to operate working chambers of the engine in a skip fire manner and that helps deliver the desired torque level; and executable computer code for adjusting the firing fraction in order to help perform the manifold vacuum-related process. - View Dependent Claims (19, 20)
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Specification