Engine misfire detection
First Claim
1. A method of detecting a malfunction of an engine, the engine having a rotating member and an angular position correlated with an angular orientation of the rotating member, the engine having an engine speed, the method comprising:
- determining the engine speed at a plurality of angular positions;
multiplying the engine speed by a sine function of the angular position to provide a first product;
passing the first product through a first low pass filter to produce a first output; and
detecting the malfunction of the engine using the first output.
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Abstract
A method of detecting an engine malfunction such as a misfire includes determining engine speed values at each of a plurality of measurement angular positions, heterodyning the engine speed values with sine and cosine functions indexed in the angular domain, passing the heterodyned results through a low pass filter, and computing the resulting magnitude from the resulting two vectors. An apparatus for detecting an engine malfunction, such as a misfire, includes an engine speed analyzer, a multiplier, and a low pass filter.
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Citations
22 Claims
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1. A method of detecting a malfunction of an engine, the engine having a rotating member and an angular position correlated with an angular orientation of the rotating member, the engine having an engine speed, the method comprising:
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determining the engine speed at a plurality of angular positions;
multiplying the engine speed by a sine function of the angular position to provide a first product;
passing the first product through a first low pass filter to produce a first output; and
detecting the malfunction of the engine using the first output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of detecting a misfire in an engine, the engine having an engine speed and an engine speed sensor providing a number of pulses per engine revolution, the method comprising:
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receiving a train of pulses from the engine speed sensor as the engine rotates;
determining the engine speed at angular intervals, the angular intervals being substantially independent of the engine speed;
determining a magnitude of engine speed variation at a given order relative to the engine speed; and
detecting the misfire from the magnitude of engine speed variation. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. An apparatus for determining an engine speed variation of an engine at a given multiple of an engine revolution time, the engine having a rotating member and an engine speed sensor providing signals at angular intervals as the rotating member rotates, the apparatus comprising:
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an engine speed analyzer receiving the signals from the engine speed sensor, the engine speed analyzer providing engine speeds at substantially regular angular intervals of engine rotation;
a first multiplier, receiving the engine speeds from the engine speed analyzer, and multiplying the engine speeds by a sine function to obtain a first product; and
a first low pass filter, receiving the first product and providing a first output, the engine speed variation being determined from the first output. - View Dependent Claims (20, 21, 22)
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Specification