Engine braking controller
First Claim
1. A method of controlling the amount of engine braking provided by an engine having at least one working chamber, the method comprising:
- determining a desired amount of engine braking; and
operating the engine in a skip cylinder engine braking mode that substantially delivers the desired amount of engine braking, wherein in the skip cylinder engine braking mode, selected working cycles of at least one selected working chamber are deactivated and other selected working cycles of the at least one selected working chamber are operated in a braking mode such that at least one working chamber is sometimes deactivated and sometimes operated in the braking mode, and wherein at least some of the working cycles operated in a braking mode, fuel is delivered to the working chambers operated in the braking mode, the working chambers operated in the braking mode are fired and the fired working chambers in the braking mode each generate a net negative torque.
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Accused Products
Abstract
In one aspect of the invention, an engine is operated in a skip cylinder engine braking mode. In the skip cylinder engine braking mode, selected working cycles of selected working chambers are deactivated. Other selected working cycles of the selected working chambers are operated in a braking mode. Accordingly, individual working chambers are sometimes deactivated and sometimes operated in the braking mode while the engine is operating in the skip cylinder engine braking mode. Various methods for cylinder control are described, which improve fuel economy, catalytic converter performance, and vehicle NVH characteristics.
83 Citations
29 Claims
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1. A method of controlling the amount of engine braking provided by an engine having at least one working chamber, the method comprising:
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determining a desired amount of engine braking; and operating the engine in a skip cylinder engine braking mode that substantially delivers the desired amount of engine braking, wherein in the skip cylinder engine braking mode, selected working cycles of at least one selected working chamber are deactivated and other selected working cycles of the at least one selected working chamber are operated in a braking mode such that at least one working chamber is sometimes deactivated and sometimes operated in the braking mode, and wherein at least some of the working cycles operated in a braking mode, fuel is delivered to the working chambers operated in the braking mode, the working chambers operated in the braking mode are fired and the fired working chambers in the braking mode each generate a net negative torque. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 22, 23, 24, 25)
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11. An engine braking controller comprising:
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a braking fraction determining unit arranged to determine a braking fraction that indicates the number of working cycles to operate in a braking mode to deliver a desired amount of engine braking wherein the available braking fractions are not limited to integer numbers of working chambers; and a braking timing determining unit arranged to direct the operation of working chambers in a manner that substantially delivers the selected braking fraction, wherein the braking controller is arranged to occasionally fire selected working cycles of at least one selected working chamber to help condition a catalytic converter and wherein net torque generated by the occasional firing of the selected working cycles of the at least one selected working chamber is negative. - View Dependent Claims (12, 13, 14, 15, 26, 27)
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16. A method of controlling the amount of engine braking in an engine having a plurality of working chambers, the method comprising:
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setting a braking fraction that indicates a fraction of working cycles to operate in a braking mode to deliver a desired amount of engine braking; determining a braking pattern that indicates on a working cycle by working cycle basis whether selected working chambers should be operated in a braking mode or deactivated; and operating the engine in accordance with the braking pattern wherein; each time a working chamber is operated in the braking mode, air is introduced into the working chamber in a manner that causes pumping losses that help deliver the desired amount of engine braking; and each time a working chamber is deactivated, air flow through the deactivated working chamber is cut off such that pumping losses are minimized; and occasionally firing selected working cycles of at least one selected working chamber to help condition a catalytic converter, wherein net torque generated by the firing of the selected working cycles of the at least one selected working chamber is negative. - View Dependent Claims (17, 18, 19, 20, 21, 28, 29)
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Specification