Internal-combustion engines – Spark ignition timing control – Electronic control
Reexamination Certificate
2001-02-12
2003-02-18
Vo, Hieu T. (Department: 3747)
Internal-combustion engines
Spark ignition timing control
Electronic control
C123S406120, C123S406380, C123S406650, C073S117020, C701S114000
Reexamination Certificate
active
06520149
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-36462 filed Feb. 15, 2000.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a knock control apparatus and method for engines which controls engine operation based on knock determination.
2. Description of Related Art
U.S. Pat. No. 4,617,895 (JP-B2-6-60621) discloses a knock control apparatus, which checks occurrence of knock accurately by varying a reference level for knock determination so that logarithmically-transformed peak levels of the output signal of a knock sensor is in a predefined pattern of the logarithmic normal distribution.
The above apparatus subjects the output signal of the knock sensor to statistical processing to determine the logarithmic normal distribution. As a result, the reference level changes instantaneously at a transient time the engine undergoes large changes in engine operating conditions or at a time of changes in a noise level caused by turning on/off of electrical loads. If the reference level changes largely in a short time, knock cannot be detected accurately.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a knock control apparatus which is capable of detecting knock accurately irrespective of large changes in engine operating conditions or in electrical loads.
According to the present invention, a knock sensor is mounted on an engine to produce a sensor signal varying its magnitude and frequency in correspondence with vibrations of the engine. A signal processor detects a signal generation period in which the sensor signal exceeds a predetermined threshold, and also a peak-related parameter of the sensor signal within the signal generation period. The peak-related parameter is either a peak of the sensor signal and a time of generation of the peak. The signal processor calculates a ratio between the peak-related parameter and the signal generation period, and determines a knock when the calculated ratio is within a predetermined range. The determination result is used to control the engine.
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Kasashima Kenji
Kokubo Naoki
Yamada Hirohiko
Denso Corporation
Nixon & Vanderhye P.C.
Vo Hieu T.
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