Abnormal combustion detection method for spark-ignition engine, and spark-ignition engine
First Claim
1. A spark-ignition engine which is provided with a vibration sensor for detecting vibration of the engine, or an in-cylinder pressure sensor for detecting an in-cylinder pressure of the engine, and designed such that a spark timing of a spark plug is set on a retard side with respect to a compression top dead center, in a low engine speed/high engine load region and in a normal state where no abnormal combustion occurs, wherein:
- the spark-ignition engine comprises a controller operable to control the spark timing of the spark plug and accept information about a vibration intensity detected by the vibration sensor or information about an in-cylinder pressure detected by the in-cylinder pressure sensor; and
the controller is operable;
when a maximum value of the vibration intensity acquired from the vibration sensor or a maximum value of the in-cylinder pressure acquired from the in-cylinder pressure sensor, in the low engine speed/high engine load region, is equal to or greater than a given threshold value, to execute a control operation of shifting the spark timing of the spark plug from the point set in the normal state on the retard side with respect to the compression top dead center, farther toward the retard side; and
when a post-spark retard maximum detection value is greater than a pre-spark retard maximum detection value, to determine that preignition occurs which is a phenomenon that an air-fuel mixture prematurely self-ignites, where;
the post-spark retard maximum detection value is the maximum value of the vibration intensity or the maximum value of the in-cylinder pressure, which is acquired from the vibration sensor or the in-cylinder pressure sensor after the retard of the spark timing; and
the pre-spark retard maximum detection value is the maximum value of the vibration intensity or the maximum value of the in-cylinder pressure, which is acquired before the retard of the spark timing.
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Accused Products
Abstract
When a maximum value of vibration intensity (maximum vibration intensity)(Vmax) acquired from a vibration sensor (33) in a low engine speed/high engine load (operating region (R)) is equal to or greater than a given threshold value (X), a spark timing of a spark plug (16) is shifted from a point set in a normal state on a retard side with respect to a compression top dead center, farther toward the retard side. Then, when a maximum vibration intensity (Vmax2) acquired after the spark timing retard is greater than a maximum vibration intensity (Vmax1) acquired before the spark timing retard, it is determined that preignition occurs. This technique makes it possible to reliably detect preignition using the vibration sensor, while distinguishing the preignition from knocking. An in-cylinder pressure sensor for detecting an in-cylinder pressure of an engine may be used to determine the presence or absence of the preignition, in the same manner.
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Citations
7 Claims
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1. A spark-ignition engine which is provided with a vibration sensor for detecting vibration of the engine, or an in-cylinder pressure sensor for detecting an in-cylinder pressure of the engine, and designed such that a spark timing of a spark plug is set on a retard side with respect to a compression top dead center, in a low engine speed/high engine load region and in a normal state where no abnormal combustion occurs, wherein:
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the spark-ignition engine comprises a controller operable to control the spark timing of the spark plug and accept information about a vibration intensity detected by the vibration sensor or information about an in-cylinder pressure detected by the in-cylinder pressure sensor; and the controller is operable; when a maximum value of the vibration intensity acquired from the vibration sensor or a maximum value of the in-cylinder pressure acquired from the in-cylinder pressure sensor, in the low engine speed/high engine load region, is equal to or greater than a given threshold value, to execute a control operation of shifting the spark timing of the spark plug from the point set in the normal state on the retard side with respect to the compression top dead center, farther toward the retard side; and when a post-spark retard maximum detection value is greater than a pre-spark retard maximum detection value, to determine that preignition occurs which is a phenomenon that an air-fuel mixture prematurely self-ignites, where;
the post-spark retard maximum detection value is the maximum value of the vibration intensity or the maximum value of the in-cylinder pressure, which is acquired from the vibration sensor or the in-cylinder pressure sensor after the retard of the spark timing; and
the pre-spark retard maximum detection value is the maximum value of the vibration intensity or the maximum value of the in-cylinder pressure, which is acquired before the retard of the spark timing. - View Dependent Claims (2, 3, 4)
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5. A method for detecting abnormal combustion in a spark-ignition engine which is provided with a vibration sensor for detecting vibration of the engine, or an in-cylinder pressure sensor for detecting an in-cylinder pressure of the engine, and designed such that a spark timing of a spark plug is set on a retard side with respect to a compression top dead center, in a low engine speed/high engine load region and in a normal state where no abnormal combustion occurs, the method comprising the steps of:
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determining whether a maximum value of a vibration intensity acquired from the vibration sensor or a maximum value of an in-cylinder pressure acquired from the in-cylinder pressure sensor, in the low engine speed/high engine load region, is equal to or greater than a given threshold value; when the maximum value of the vibration intensity or the maximum value of the in-cylinder pressure is equal to or greater than the threshold value, shifting the spark timing of the spark plug from the point set in the normal state on the retard side with respect to the compression top dead center, farther toward the retard side; and when a post-spark retard maximum detection value is greater than a pre-spark retard maximum detection value, determining that preignition occurs which is a phenomenon that an air-fuel mixture prematurely self-ignites, where;
the post-spark retard maximum detection value is the maximum value of the vibration intensity or the maximum value of the in-cylinder pressure, which is acquired from the vibration sensor or the in-cylinder pressure sensor after the retard of the spark timing; and
the pre-spark retard maximum detection value is the maximum value of the vibration intensity or the maximum value of the in-cylinder pressure, which is acquired before the retard of the spark timing. - View Dependent Claims (6, 7)
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Specification