Combustion state-detecting system for internal combustion engines
First Claim
1. A combustion state-detecting system for an internal combustion engine having at least one spark plug, and a crankshaft, comprising:
- crank angle signal-generating means for generating a crank angle signal with a predetermined period shorter than a firing period of said spark plug whenever said crankshaft rotates through a predetermined angle;
engine speed-detecting means for detecting a value of rotational speed of said engine whenever said crank angle signal is generated;
first averaging means for continuously averaging values of the rotational speed of said engine detected by said engine speed-detecting means, over a period of one rotation of said crankshaft, to obtain a first average value;
second averaging means for averaging said first average values of the engine rotational speed obtained by said first averaging means, over said firing period of said spark plug, to obtain a second average value;
variation amount-calculating means for calculating an amount of variation in said second average value of the rotational speed of said engine obtained by said second averaging means, over said firing period of said spark plug; and
combustion state-determining means for comparing said amount of variation with a predetermined value to determine whether said engine is in a degraded state of combustion.
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Abstract
A combustion state-detecting system, for internal combustion engines, has a crank angle sensor. The crank angle sensor generates a crank angle signal with a predetermined period shorter than a firing period of the engine whenever the crankshaft rotates through a predetermined angle. A value of the rotational speed of the engine is detected whenever the crank angle signal is generated. A first average value of the detected engine rotational speed is calculated over a period of one rotation of the crankshaft, followed by calculating a second average value of the first average value over every firing period, to thereby calculate a rate of variation in the second average value over every firing period. The rate of variation is compared with a predetermined value, to determine whether or not the engine is in a degraded state of combustion.
20 Citations
6 Claims
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1. A combustion state-detecting system for an internal combustion engine having at least one spark plug, and a crankshaft, comprising:
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crank angle signal-generating means for generating a crank angle signal with a predetermined period shorter than a firing period of said spark plug whenever said crankshaft rotates through a predetermined angle; engine speed-detecting means for detecting a value of rotational speed of said engine whenever said crank angle signal is generated; first averaging means for continuously averaging values of the rotational speed of said engine detected by said engine speed-detecting means, over a period of one rotation of said crankshaft, to obtain a first average value; second averaging means for averaging said first average values of the engine rotational speed obtained by said first averaging means, over said firing period of said spark plug, to obtain a second average value; variation amount-calculating means for calculating an amount of variation in said second average value of the rotational speed of said engine obtained by said second averaging means, over said firing period of said spark plug; and combustion state-determining means for comparing said amount of variation with a predetermined value to determine whether said engine is in a degraded state of combustion. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification