Misfire detector for an internal combustion engine
First Claim
1. A misfire detector of an internal combustion engine utilizing a crankshaft capable of rotating, the detector comprising:
- a map for storing misfire determination values as a basis for determining engine misfiring, the map adopting a plurality of crankshaft rotation periods as parameters such that each misfire determination value is associated with one of the plurality of crankshaft rotation periods;
means for computing an engine speed fluctuation quantity, according to an engine speed, for a predetermined period of time; and
means for detecting a misfire according to the stored misfire determination values and the computed engine speed fluctuation quantity.
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Accused Products
Abstract
A misfire detector calculates the engine speed fluctuation quantity Δωn for a predetermined period of time on the basis of the average engine speed on, which is the reciprocal of the time T120n that the crankshaft of the engine takes to turn 120 degrees. By comparing the calculated engine speed fluctuation quantity Δωn with a misfire determination value REF, from which it can be determined whether the engine is misfiring, the misfire detector determines whether the engine is misfiring. The misfire detector detects the rotational fluctuation per combustion stroke of each engine cylinder and learns the variation of the detected rotational fluctuation values during normal combustion. From this learned value and the detected rotational fluctuation value per combustion stroke of the cylinder, the misfire detector determines whether the cylinder is misfiring or not.
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Citations
22 Claims
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1. A misfire detector of an internal combustion engine utilizing a crankshaft capable of rotating, the detector comprising:
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a map for storing misfire determination values as a basis for determining engine misfiring, the map adopting a plurality of crankshaft rotation periods as parameters such that each misfire determination value is associated with one of the plurality of crankshaft rotation periods; means for computing an engine speed fluctuation quantity, according to an engine speed, for a predetermined period of time; and means for detecting a misfire according to the stored misfire determination values and the computed engine speed fluctuation quantity. - View Dependent Claims (2, 3, 4)
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5. A misfire detector for an internal combustion engine of a vehicle, comprising:
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means for detecting rotational fluctuation values of the engine; means for learning variation values of the rotational fluctuation values detected by the rotational fluctuation detecting means; means for determining from the variation values learned by the learning means and the rotational fluctuation value detected by the rotational fluctuation detecting means to determine whether the engine is misfiring; a random access memory (RAM) for storing the learned value; and a rewritable nonvolatile memory for storing the learned value, wherein the learned value stored in the RAM is rewritten every time the learning means computes a new learned value; and wherein the learned value stored in the nonvolatile memory is rewritten only on a predetermined condition. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. A method of detecting a misfire of an internal combustion engine utilizing a crankshaft, the method comprising:
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storing misfire determination values in a map as a basis for determining engine misfiring, the map adopting a plurality of crankshaft rotation periods as parameters such that each misfire determination value is associated with one of the plurality of crankshaft rotation periods; computing an engine speed fluctuation quantity, according to an engine speed, for a predetermined period of time; and detecting a misfire according to the stored misfire determination values and the computed engine speed fluctuation quantity. - View Dependent Claims (13, 14, 15)
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16. A method of detecting a misfire in an internal combustion engine of a vehicle, the method comprising:
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detecting rotational fluctuation values of the engine; determining variation values of the detected rotational fluctuation values; determining from the determined variation values and the detected rotational fluctuation value whether the engine is misfiring; storing the determined value in a random access memory (RAM); and storing the determined value in a rewritable nonvolatile memory, wherein the determined value stored in the RAM is rewritten every time a new determined value is computed; and wherein the determined value stored in the nonvolatile memory is rewritten only on a predetermined condition. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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Specification