COMBUSTION STATE DIAGNOSING SYSTEM AND COMBUSTION STATE DIAGNOSING METHOD FOR DIAGNOSING ENGINE AND RECORDING MEDIUM
First Claim
1. A combustion state diagnosing system for diagnosing a combustion state of a multiple-cylinder engine by measuring a parameter of the combustion state varying according to the combustion state of the engine, such as engine speed or output torque, diagnosing the combustion state on the basis of the parameter of the combustion state, said diagnostic system comprising:
- a combustion state parameter measuring means which measures values of parameter of the combustion state N times (at least once) in one ignition cycle of the multiple-cylinder engine at times corresponding to a predetermined crank angle;
a specific rotation period component extracting means for extracting a specific rotation period component of a period synchronous with rotation of a crankshaft from values of the parameter of the combustion state measured by the combustion state parameter measuring means at least in two rotations of a crankshaft; and
a combustion state judging means for judging the combustion state on the basis of the specific rotation period component extracted by the specific rotation period component extracting means.
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Abstract
It is an object of the present invention to provide a low-cost combustion state diagnosing system and a combustion state diagnosing method capable of accurately detecting misfires which occur at a low frequency while a multiple-cylinder engine is operating at a high engine speed under a low load.
The object can be achieved, when diagnosing combustion state, by extracting specific rotation period component of a period synchronous with rotation from a combustion state parameter for at least two rotations, and judging combustion state on the basis of the extracted specific rotation period component. The combustion state parameter may be the engine speed or the output torque of a multiple-cylinder engine which varies according to the combustion state of the engine.
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Citations
14 Claims
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1. A combustion state diagnosing system for diagnosing a combustion state of a multiple-cylinder engine by measuring a parameter of the combustion state varying according to the combustion state of the engine, such as engine speed or output torque, diagnosing the combustion state on the basis of the parameter of the combustion state, said diagnostic system comprising:
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a combustion state parameter measuring means which measures values of parameter of the combustion state N times (at least once) in one ignition cycle of the multiple-cylinder engine at times corresponding to a predetermined crank angle;
a specific rotation period component extracting means for extracting a specific rotation period component of a period synchronous with rotation of a crankshaft from values of the parameter of the combustion state measured by the combustion state parameter measuring means at least in two rotations of a crankshaft; and
a combustion state judging means for judging the combustion state on the basis of the specific rotation period component extracted by the specific rotation period component extracting means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An engine combustion state diagnosing program storage medium storing a program for measuring a combustion state parameter varying according to the combustion state of a multiple-cylinder engine, such as engine speed at which the multiple-cylinder engine is operating or output torque of the multiple-cylinder engine and judging combustion state on the basis of the combustion state parameter;
- wherein the program specifies steps of;
measuring the combustion state parameter N times (at least once) in one ignition cycle of each cylinder at a predetermined crank angle, extracting a specific rotation period component of a period synchronous with rotation from at least the two values of the combustion state parameter, and judging combustion state on the basis of the extracted specific rotation period component.
- wherein the program specifies steps of;
Specification