Manifold pressure and air charge model
First Claim
1. An engine controller arranged to direct skip fire operation of an internal combustion engine having a plurality of working chambers and an intake manifold, the engine controller comprising:
- a firing controller arranged to direct operation of the engine in a skip fire mode, the firing controller being arranged to direct a sequence of skip fire firings that delivers a desired engine output while operating at a first effective displacement, wherein during operation of the engine in the skip fire mode at the first effective displacement, a selected one of the working chambers will sometimes be skipped during a first firing opportunity of the selected working chamber and sometime be fired during an immediately following second firing opportunity of the selected working chamber; and
a mass air charge determining unit that is arranged to, for each fired firing opportunity of the plurality of working chambers;
(i) determine a number of firings of all of the working chambers that will have taken place within a designated window corresponding to a fixed number of firing opportunities that immediately preceded such fired firing opportunity;
(ii) determine a firing ratio wherein the firing ratio is a ratio of firings to firing opportunities in the window with the ratio being fractionally less than or equal to 1; and
(iii) estimate a mass air charge based on the firing ratio wherein the mass air charge estimation takes into account fluctuations of intake manifold pressure resulting from skipped firing opportunities; and
cause fuel to be delivered to the working chamber associated with the fired firing opportunity for which the estimated mass air charge was determined based on the estimated mass air charge.
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Accused Products
Abstract
In one aspect, an engine controller for an engine including multiple working chambers is described. The engine controller includes a mass air charge determining unit that estimates a mass air charge or amount of air to be delivered to a working chamber. Firing decisions made for a firing window of one or more firing opportunities are used to help determine the mass air charge. The engine controller also includes a firing controller, which is arranged to direct firings to deliver a desired output. Fuel is delivered to a working chamber based on the estimated mass air charge.
73 Citations
21 Claims
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1. An engine controller arranged to direct skip fire operation of an internal combustion engine having a plurality of working chambers and an intake manifold, the engine controller comprising:
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a firing controller arranged to direct operation of the engine in a skip fire mode, the firing controller being arranged to direct a sequence of skip fire firings that delivers a desired engine output while operating at a first effective displacement, wherein during operation of the engine in the skip fire mode at the first effective displacement, a selected one of the working chambers will sometimes be skipped during a first firing opportunity of the selected working chamber and sometime be fired during an immediately following second firing opportunity of the selected working chamber; and a mass air charge determining unit that is arranged to, for each fired firing opportunity of the plurality of working chambers; (i) determine a number of firings of all of the working chambers that will have taken place within a designated window corresponding to a fixed number of firing opportunities that immediately preceded such fired firing opportunity; (ii) determine a firing ratio wherein the firing ratio is a ratio of firings to firing opportunities in the window with the ratio being fractionally less than or equal to 1; and (iii) estimate a mass air charge based on the firing ratio wherein the mass air charge estimation takes into account fluctuations of intake manifold pressure resulting from skipped firing opportunities; and cause fuel to be delivered to the working chamber associated with the fired firing opportunity for which the estimated mass air charge was determined based on the estimated mass air charge. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An engine controller arranged to direct skip fire operation of an internal combustion engine having a plurality of working chambers and an intake manifold, the engine controller comprising:
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a firing controller arranged to direct operation of the engine in a skip fire mode, the firing controller being arranged to direct a sequence of skip fire firings that delivers a desired engine output while operating at a first effective displacement, wherein during operation of the engine in the skip fire mode at the first effective displacement, a selected one of the working chambers will sometimes be skipped during a first firing opportunity of the selected working chamber and sometime be fired during an immediately following firing opportunity of the selected working chamber; and a mass air charge determining unit that is arranged to, for each fired firing opportunity of the plurality of working chambers; (i) count the number of firings that occur during a window of two or more firing opportunities of the plurality of working chambers that immediately preceded such fired firing opportunity; (ii) calculate a firing ratio based at least in part on the number of counted firings and the number of firing opportunities in the window, the firing ratio being a ratio less than or equal to one, wherein the firing ratio will sometimes be different for different sequential fired firing opportunities during operation of the engine at the first effective displacement; and (iii) estimate a mass air charge based on the firing ratio which takes into account fluctuations of intake manifold pressure resulting from skipped firing opportunities, wherein the estimated mass air charge is calculated without input from a sensor that directly reads the pressure within an intake manifold. - View Dependent Claims (14, 15, 20, 21)
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16. A method for control of an internal combustion engine having a plurality of working chambers during skip fire operation of the engine, wherein during skip fire operation of the engine at a first effective displacement, a selected one of the working chambers will sometimes be skipped during a first firing opportunity of the selected working chamber and sometime be fired during an immediately following firing opportunity of the selected working chamber, the method comprising:
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measuring air flow into an intake manifold; determining an intake valve timing; determining an exhaust valve timing; sensing an engine speed; determining a manifold air temperature; and for each fired firing opportunity of the plurality of working chambers during the skip fire operation of the engine, (i) determining a number of firings that took place in a window of a plurality of firing opportunities that immediately preceded such fired firing opportunity; (ii) calculating a firing ratio, wherein the firing ratio indicates a ratio of firings to firing opportunities in the window, the ratio being less than or equal to one; and (iii) calculating a mass air charge for such fired firing opportunity based at least in part on the measured air mass flow, the firing ratio, the engine speed, and the manifold air temperature wherein the calculation of the mass air charge takes into account fluctuations of intake manifold pressure resulting from skipped firing opportunities; and (iv) delivering fuel to such working chamber based on the calculated mass air charge. - View Dependent Claims (17, 18, 19)
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Specification