Engine diagnostics with skip fire control
First Claim
1. A method comprising:
- operating a engine in a skip fire manner to deliver a desired engine output;
identifying a time period during skip fire operation that is suitable for initiating or performing a selected engine diagnosis, wherein the selected engine diagnosis utilizes a sensor that is associated with a group of cylinders and the identified time period is one selected from the group consisting of (i) a time period in which a single first cylinder in the group of cylinders is fired a plurality of times in isolation relative to the sensor used in the diagnosis, and (ii) a time period in which no cylinder in a first bank of cylinders associated with the sensor used in the diagnosis is fired over the course of at least one engine cycle while at least one other cylinder not associated with the first bank of cylinder is fired; and
conducting or initiating the selected engine diagnosis during the identified time period while the engine is operated in a skip fire manner to deliver the desired engine output.
1 Assignment
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Accused Products
Abstract
Methods and devices are described for performing engine diagnostics during skip fire operation of an engine while a vehicle is being driven. Knowledge of the firing sequence is used to determine appropriate times to conduct selected diagnostics and/or to help better interpret sensor inputs or diagnostic results. In one aspect, selected diagnostics are executed when a single cylinder is fired a plurality of times in isolation relative to a sensor used in the diagnosis. In another aspect, selected diagnostics are conducted while the engine is operated using a firing sequence that insures that no cylinders in a first cylinder bank are fired for a plurality of engine cycles while cylinders in a second bank are at least sometimes fired. The described tests can be conducted opportunistically, when conditions are appropriate, or specific firing sequences can be commanded to achieve the desired isolation or skipping of one or more selected cylinders.
62 Citations
28 Claims
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1. A method comprising:
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operating a engine in a skip fire manner to deliver a desired engine output;
identifying a time period during skip fire operation that is suitable for initiating or performing a selected engine diagnosis, wherein the selected engine diagnosis utilizes a sensor that is associated with a group of cylinders and the identified time period is one selected from the group consisting of (i) a time period in which a single first cylinder in the group of cylinders is fired a plurality of times in isolation relative to the sensor used in the diagnosis, and (ii) a time period in which no cylinder in a first bank of cylinders associated with the sensor used in the diagnosis is fired over the course of at least one engine cycle while at least one other cylinder not associated with the first bank of cylinder is fired; andconducting or initiating the selected engine diagnosis during the identified time period while the engine is operated in a skip fire manner to deliver the desired engine output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A diagnostics module for use in diagnosing a vehicle engine while the vehicle is being driven and the engine is being operated in a skip fire mode, the diagnostics module including computer code embodied in a computer readable media arranged to:
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identify a time period while the vehicle is being driven with the engine operating using skip fire control, that is suitable for initiating or performing a selected engine diagnosis, wherein the selected engine diagnosis utilizes a sensor that is associated with a group of cylinders and the identified time period is one selected from the group consisting of (i) a time period in which a single first cylinder in the group of cylinders is fired a plurality of times in isolation relative to the sensor used in the diagnosis, and (ii) a time period in which no cylinder in a first bank of cylinders associated with the sensor used in the diagnosis is fired over the course of at least one engine cycle while at least one other cylinder not associated with the first bank of cylinder is fired; and conduct or initiate the selected engine diagnosis during the identified time period while the vehicle is being driven with the engine operating using skip fire control. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification