Induction diagnostics for skip fire engines
First Claim
1. A method of detecting an induction fault of a cylinder in an internal combustion engine having a crankshaft, the method comprising:
- measuring the angular acceleration of the crankshaft to generate a crankshaft acceleration signal;
comparing the crankshaft angular acceleration signal with a reference angular acceleration wherein the reference is based at least in part on a commanded skip/fire decision; and
generating a fault signal when an induction fault is detected, wherein the induction fault detection is based at least in part on a determination that the crankshaft angular acceleration signal has deviated from the reference angular acceleration by at least a prescribed threshold.
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Accused Products
Abstract
A variety of methods and arrangements for detecting failure of the commanded air induction in an internal combustion engine are described. In some embodiments, the intake manifold pressure is monitored. An air induction event generates a fluctuation in the intake manifold pressure, which is recorded. The signal is processed through a diagnostic filter to help determine whether the actual induction matched the commanded induction. In other embodiments, measured crankshaft acceleration is compared with estimated crankshaft acceleration. If the two quantities differ by a threshold amount an induction fault is detected. The two detection methods may also be combined. The describe approaches are particularly well suited for use in engines operating in a skip fire mode with cylinder deactivation and/or a dynamic firing level modulation mode.
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Citations
32 Claims
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1. A method of detecting an induction fault of a cylinder in an internal combustion engine having a crankshaft, the method comprising:
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measuring the angular acceleration of the crankshaft to generate a crankshaft acceleration signal; comparing the crankshaft angular acceleration signal with a reference angular acceleration wherein the reference is based at least in part on a commanded skip/fire decision; and generating a fault signal when an induction fault is detected, wherein the induction fault detection is based at least in part on a determination that the crankshaft angular acceleration signal has deviated from the reference angular acceleration by at least a prescribed threshold. - View Dependent Claims (2, 3)
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4. An engine control unit arranged to control the operation of an engine, the engine control unit including an induction fault detection unit, the induction fault detection unit comprising:
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a crankshaft angular acceleration comparator that compares a measured crankshaft angular acceleration with an expected crankshaft angular acceleration, wherein the expected crankshaft angular acceleration is based at least in part on a commanded skip/fire decision; and wherein the induction fault detection unit is configured to generate a fault signal when an induction fault is detected, wherein the induction fault detection is based at least in part on a determination that the measured crankshaft angular acceleration has deviated from the expected angular acceleration by more than a prescribed amount. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 29, 30, 31)
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12. An engine control unit arranged to control the operation of an engine, the engine control unit including an induction fault detection unit, the induction fault detection unit comprising:
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a manifold pressure comparator that compares a measured intake manifold pressure with an expected intake manifold pressure; a crankshaft angular acceleration comparator that compares a measured crankshaft angular acceleration with an expected crankshaft angular acceleration; and wherein the induction fault detection unit is configured to generate a fault signal when an induction fault is detected, wherein the induction fault detection is based at least in part on a determination that both (i) the measured intake manifold pressure has deviated from the expected intake manifold pressure by more than a first prescribed threshold, and (ii) the measured crankshaft angular acceleration has deviated from the expected crankshaft angular acceleration by more than a second prescribed threshold. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method of detecting an induction fault of a cylinder in an internal combustion engine having an intake manifold and crankshaft, the method comprising:
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measuring the intake manifold pressure; comparing the measured intake manifold pressure with an expected intake manifold pressure; measuring the crankshaft angular acceleration; comparing the measured crankshaft angular acceleration with an expected crankshaft angular acceleration; generating a fault signal when an induction fault is detected, wherein the induction fault detection is based at least in part on a determination that both (i) the measured intake manifold pressure has deviated from the expected intake manifold pressure by more than a first prescribed threshold, and (ii) the measured crankshaft angular acceleration has deviated from the expected crankshaft angular acceleration by more than a second prescribed threshold. - View Dependent Claims (26, 27, 28, 32)
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Specification