Misfire deciding method and misfire deciding system for internal combustion engines
First Claim
1. A misfire deciding method for an internal combustion engine, which comprises:
- acquiring an internal pressure measured value based on the internal pressure of an internal combustion engine, to which a spark plug is attached, from the output of a pressure sensor mounted in a mounting seat of said spark plug;
calculating the integrated value of said internal pressure measured values for a first constant integration period after an intake valve is closed and before a crank angle reaches top dead center, and setting the calculated value to a before top dead center integrated value S1;
calculating the integrated value of said internal pressure measured values for a second constant integration period after said crank angle reaches top dead center and before an exhaust valve is opened, and setting the calculated value to an after top dead center integrated value S2;
calculating a differential integrated value S1−
S2 between said after top dead center integrated value S2 and said before top dead center integrated value S1; and
calculating a first correction reference value using the internal pressure measured value at a correction measurement point set for said first integration period, to correct said differential integrated value with said first correction reference value, and making a misfire decision on the basis of the corrected differential integrated value.
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Accused Products
Abstract
A misfire deciding method for an internal combustion engine, which can be executed conveniently at low cost by using a gasket type pressure sensor and which can decide a misfire highly accurately and reproducibly. The internal pressure of an internal combustion engine having a spark plug mounted therein is measured by a pressure sensor (or a gasket type pressure sensor) mounted in the mounting seat of the spark plug. The measured information of the internal pressure for a period (or a before top dead center period) after an intake valve is closed and before the crank angle reaches top dead center is used as the before top dead center pressure information, and the measured information of the internal pressure for a period (or an after top dead center period) after the crank angle reaches the top dead center and before an exhaust valve is opened is used as the after top dead center pressure information. Misfire of the internal combustion engine is decided on the basis of misfire decision information obtained using the before top dead center pressure information and the after top dead center pressure information.
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Citations
11 Claims
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1. A misfire deciding method for an internal combustion engine, which comprises:
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acquiring an internal pressure measured value based on the internal pressure of an internal combustion engine, to which a spark plug is attached, from the output of a pressure sensor mounted in a mounting seat of said spark plug;
calculating the integrated value of said internal pressure measured values for a first constant integration period after an intake valve is closed and before a crank angle reaches top dead center, and setting the calculated value to a before top dead center integrated value S1;
calculating the integrated value of said internal pressure measured values for a second constant integration period after said crank angle reaches top dead center and before an exhaust valve is opened, and setting the calculated value to an after top dead center integrated value S2;
calculating a differential integrated value S1−
S2 between said after top dead center integrated value S2 and said before top dead center integrated value S1; and
calculating a first correction reference value using the internal pressure measured value at a correction measurement point set for said first integration period, to correct said differential integrated value with said first correction reference value, and making a misfire decision on the basis of the corrected differential integrated value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A misfire deciding system for an internal combustion engine, comprising:
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a pressure sensor mounted in a mounting seat of a spark plug for acquiring an internal pressure measured value based on the internal pressure of an internal combustion engine having the spark plug mounted therein; and
a decision unit for;
calculating the integrated value of said internal pressure measured values for a first constant integration period after an intake valve is closed and before a crank angle reaches the top dead center, and setting the calculated value to a before top dead center integrated value S1;
calculating the integrated value of said internal pressure measured values for a second constant integration period after said crank angle reaches top dead center and before an exhaust valve is opened, and setting the calculated value to an after top dead center integrated value S2;
calculating a differential integrated value S1−
S2 between said after top dead center integrated value S2 and said before top dead center integrated value S1; and
calculating a first correction reference value using the internal pressure measured value at a correction measurement point set for said first integration period, to correct said differential integrated value with said first correction reference value, and making a misfire decision on the basis of the corrected differential integrated value.
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Specification