Method and apparatus for ignition timing control of internal combustion engine
AssigneeNippondenso Co., Ltd.
InventorsKatsuharu Hosoe, Yasuhito Takasu, Toshiharu Iwata
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Abstract
Ignition timing for an internal combustion engine is controlled by subtracting a retard correction amount from a basic ignition timing. When engine knocking is detected, the retard correction amount is retarded from the basic ignition timing, but not so that the controlled timing drops below a predetermined limit. If knocking is not detected, the retard correction amount is advanced to thereby control the ignition timing towards, but not exceeding, a knocking limit.
Claims8
A method of controlling ignition timing for an internal combustion engine, comprising the steps of:
- detecting revolution speed of said engine;
- detecting load exerted on said engine;
- determining a basic ignition timing .theta..sub.B based on said detected speed and load, said .theta..sub.B representing an upper knocking limit of said engine;
- sensing the occurrence of knocking in said engine;
- and
- computing an engine timing .theta., based on said basic timing .theta..sub.B and an amount of retard correction .theta..sub.c, to be appiled to said engine, wherein .theta..sub.c is advanced if no knocking is sensed and retarded if knocking is sensed, and wherein said computing step further includes the steps of:
- determining a retard amount .DELTA..theta. based on said sensed knocking,
- computing said amount of retard correction .theta..sub.c based on said determined retard amount .DELTA..theta. and the most recent previous value of .theta..sub.c,
- limiting said amount of retard correction .theta..sub.c to a value no more than a maximum value .theta..sub.c max,
- calculating the ignition timing .theta. to be applied to said engine by subtracting .theta..sub.c from .theta..sub.B, and
- setting .theta. equal to a defined minimum value .theta..sub.min whenever said calculation of .theta. yields a value less than .theta..sub.min.
An aparatus for controlling ignition timing of an internal combustion engine, comprising:
- detector means for detecting revolution speed of and load exerted on said engine;
- basic timing means for determinig a basic ignition timing .theta..sub.B based on the detections of said detector means, said .theta..sub.B representing an upper knocking limit of said engine;
- knock sensor means for sensing the occurrence of knocking in said engine;
- and
- engine ignition timing means for determining actual ignition timing .theta. for application to said engine based on said basic ignition timing and said sensed occurrence of knocking, said engine ignition timing means including
- means for determining an amount of retard .DELTA..theta. based on said sensed knocking,
- means for calculating a retard correction amount .theta..sub.c based on .DELTA..theta. and the most recent value of .theta..sub.c,
- means for setting .theta..sub.c at a maximum value .theta..sub.c max if said calculated amount of retard correction exceeds .theta..sub.c max,
- means for determining the actual ignition timing .theta. by substracting the retard correction amount .theta..sub.c from the basic ignition timing .theta..sub.B, and
- means for setting .theta. at a minimum value .theta..sub.min if said determined actual ignition timing falls below .theta..sub.min .
Dependencies are inferred from the claim text.