Adaptive correction of torsional and wheel profile position irregularities for misfire detection
First Claim
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1. A method of obtaining adaptive correction factors to detect malfunctions in an internal combustion engine, said method comprising the steps of:
- measuring an engine variable at a plurality of different times to produce raw values of said engine variable;
correcting said raw values by applying a respective adaptive correction factor to each raw value to produce corrected values;
selecting one of said adaptive correction factors for updating;
selecting a block of consecutive corrected values including a particular corrected value that has been corrected using said one selected adaptive correction factor;
comparing said particular corrected value with other said corrected values of said block; and
if said particular corrected value is more closely indicative of said malfunction than each of said other corrected values of said block, then updating said particular adaptive correction factor in a first manner without regard to the raw value corresponding to said particular corrected value, otherwise, if said particular corrected value is not more closely indicative of said malfunction than each of said other corrected values of said block, then updating said particular adaptive correction factor in a second manner responsive to said raw value corresponding to said particular corrected value.
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Abstract
A crankshaft based misfire detector for an internal combustion engine detects and identifies misfire over a broad range of engine operating conditions by establishing correction factors to compensate for crankshaft torsional oscillations and static wheel profile errors which corrupt the acceleration signals used to detect misfire. The correction factors are adaptively determined during in-use engine operation and are updated in one manner for most firings but in another manner for any cylinder firing which had the relatively lowest corrected acceleration within an engine cycle.
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Citations
11 Claims
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1. A method of obtaining adaptive correction factors to detect malfunctions in an internal combustion engine, said method comprising the steps of:
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measuring an engine variable at a plurality of different times to produce raw values of said engine variable; correcting said raw values by applying a respective adaptive correction factor to each raw value to produce corrected values; selecting one of said adaptive correction factors for updating; selecting a block of consecutive corrected values including a particular corrected value that has been corrected using said one selected adaptive correction factor; comparing said particular corrected value with other said corrected values of said block; and if said particular corrected value is more closely indicative of said malfunction than each of said other corrected values of said block, then updating said particular adaptive correction factor in a first manner without regard to the raw value corresponding to said particular corrected value, otherwise, if said particular corrected value is not more closely indicative of said malfunction than each of said other corrected values of said block, then updating said particular adaptive correction factor in a second manner responsive to said raw value corresponding to said particular corrected value.
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2. A method of obtaining adaptive correction factors to determine crankshaft acceleration in a misfire detector for an internal combustion engine with N cylinders, said method comprising the steps of:
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measuring a plurality of raw acceleration values each corresponding to a respective engine rotation interval, each engine rotation interval corresponding to a power stroke of a respective engine cylinder; correcting said raw acceleration values to produce corrected acceleration values in response to a plurality of respective adaptive correction factors, each adaptive correction factor corresponding to a respective engine cylinder; selecting one of said adaptive correction factors, corresponding to a particular engine cylinder, for updating; selecting a block of N consecutive corrected acceleration values including a particular corrected acceleration value corresponding to said particular engine cylinder; comparing said particular corrected acceleration value with the other said corrected acceleration values of said block; and if said particular corrected acceleration value is less than each of said other corrected acceleration values of said block, then updating said particular adaptive correction factor in a first manner without regard to the raw acceleration value corresponding to said particular corrected acceleration value, otherwise, if said particular corrected acceleration value is not less than each of said other corrected acceleration values of said block, then updating said particular adaptive correction factor in a second manner responsive to said raw acceleration value corresponding to said particular corrected acceleration value. - View Dependent Claims (3, 4, 5, 6, 7)
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8. Apparatus for detecting misfires during individual cylinder firings in an internal combustion engine having N cylinders, comprising:
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timing means for measuring crankshaft rotation intervals corresponding to respective power strokes of said N cylinders; raw acceleration means coupled to said timing means for determining raw acceleration values corresponding to respective power strokes in response to said crankshaft rotation intervals; correction means coupled to said raw acceleration means for correcting said raw acceleration values to produce corrected acceleration values in response to a plurality of respective adaptive correction factors, each adaptive correction factor corresponding to a respective engine cylinder; and updating means coupled to said correction means for
1) selecting one of said adaptive correction factors, corresponding to a particular engine cylinder, for updating,
2) selecting a block of N consecutive corrected acceleration values including a particular corrected acceleration value corresponding to said particular engine cylinder,
3) comparing said particular corrected acceleration value with the other said corrected acceleration values of said block,
4) updating said particular adaptive correction factor in a first manner without regard to the raw acceleration value corresponding to said particular corrected acceleration value if said particular corrected acceleration value is less than each of said other corrected acceleration values of said block, and
5) updating said particular adaptive correction factor in a second manner responsive to said raw acceleration value corresponding to said particular corrected acceleration value if said particular corrected acceleration value is not less than each of said other corrected acceleration values of said block. - View Dependent Claims (9, 10, 11)
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Specification