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A system for controlling ignition timing in an engine wherein a knocking signal is generated by a sensor in response to knocking. The operation of the sensor is monitored, and when a fault in its operation is detected, a dummy signal, instead of the knocking signal, is used to control engine timing.

A system for controlling ignition timing in an engine wherein a knocking signal is generated by a sensor in response to knocking. The operation of the sensor is monitored, and when a fault in its operation is detected, a dummy signal, instead of the knocking signal, is used to control engine timing. The dummy signal causes the engine timing to be retarded to a value at which knocking is unlikely to occur.

대표청구항 ▼

1. A system for controlling ignition timing of an engine comprising: means for generating an operation signal related to an operating condition of said engine; means for generating a knocking signal related to knocking in said engine; means for controlling said ignition timing in response to sa

1. A system for controlling ignition timing of an engine comprising: means for generating an operation signal related to an operating condition of said engine; means for generating a knocking signal related to knocking in said engine; means for controlling said ignition timing in response to said operation signal and said knocking signal; means for determining a peak value of said knocking signal; means for generating a fault signal when said peak value is beyond a predetermined threshold; means for generating a dummy signal, said dummy having the effect of retarding said ignition timing to a timing at which knocking is unlikely to occur when said dummy signal is applied to said controlling means; and means for substituting said dummy signal for said knocking signal to said controlling means in response to said fault signal. 2. A system for controlling ignition timing of an engine comprising: means for generating first and second operation signals related to first and second operating conditions of said engine; means for generating a knocking signal related to knocking in said engine; means for controlling said ignition timing in response to said first operation signal and said knocking signal; means for generating a fault signal when said knocking signal generating means is inoperative; means for generating a dummy signal, said dummy having the effect of retarding said ignition timing to a timing at which knocking is unlikely to occur when said dummy signal is applied to said controlling means; gate means, responsive to said second operating signal and said fault signal, for generating a control signal when said second operation signal achieves a predetermined threshold and said fault signal is generated; and means for substituting said dummy signal for said knocking signal to said controlling means in response to said control signal. 3. A system as in claim 2 wherein: said system further comprises means for determining a peak value of said knocking signal; and said fault signal generating means includes means for generating said fault signal when said peak value is beyond a predetermined threshold. 4. A system as in claim 2 or 3 wherein: said first and second operation signal generating means includes means for detecting engine load, said second operation signal being an output of said load detecting means; and said gate means generates said control signal when said second operating signal indicates a high load. 5. A system for controlling ignition timing of an engine comprising: means for generating an operation signal related to an operating condition of said engine; means for generating a load signal when a load on said engine is high; means for generating a knocking signal related to knocking in said engine; means for controlling said ignition timing in response to said operation signal and said knocking signal; means for determining a peak value of said knocking signal; means for generating a fault signal when said peak value is beyond a predetermined threshold, indicative of inoperativeness of said knocking signal generating means; means for generating a dummy signal, said dummy having the effect of retarding said ignition timing to a timing at which knocking is unlikely to occur when said dummy signal is applied to said controlling means; an AND gate, responsive to said load signal and said fault signal, for generating a control signal when said engine load is high and said knocking signal generating means is inoperative; and means for substituting said dummy signal for said knocking signal to said controlling means in response to said control signal. 6. A system as in claim 1, 2 or 5 further comprising indicator means for informing an operator when said dummy signal is applied to said controlling means. 7. A system for controlling ignition timing of an engine comprising: means for generating an operation signal related to an operating condition of said engine; a knocking sensor having an internal resistance related to knocking in said engine; means for controlling said ignition timing in response to said operation signal and said knocking sensor; a resistance connected in series with said knocking sensor; means for applying a voltage across said knocking sensor and said resistance; means for generating a fault signal when a voltage between said knocking sensor and said resistance crosses a predetermined threshold indicative of said knocking sensor being inoperative; means for generating a dummy signal, said dummy having the effect of retarding said ignition timing to a timing at which knocking is unlikely to occur when said dummy signal is applied to said controlling means; and means for substituting said dummy signal for said knocking signal to said controlling means in response to said fault signal. 8. A method of controlling ignition timing of an engine comprising the steps of: generating an operation signal related to an operating condition of said engine; generating a knocking signal related to knocking in said engine; controlling said ignition timing in response to said operation signal and said knocking signal; determining a peak value of said knocking signal; generating a fault signal when said peak value is beyond a predetermined threshold; generating a dummy signal, said dummy having the effect of retarding said ignition timing to a timing at which knocking is unlikely to occur when said controlling step is responsive to said dummy signal; and substituting said dummy signal for said knocking signal in said controlling step in response to said fault signal. 9. A method of controlling ignition timing of an engine comprising: generating first and second operation signals related to first and second operating conditions of said engine; generating a knocking signal related to knocking in said engine; controlling said ignition timing in response to said first operation signal and said knocking signal; generating a fault signal when said knocking signal generating step is inoperative; generating a dummy signal, said dummy having the effect of retarding said ignition timing to a timing at which knocking is unlikely to occur when said control step is responsive to said dummy signal; generating, in response to said second operating signal and said fault signal, a control signal when said second operation signal achieves a predetermined threshold and said fault signal is generated; and substituting said dummy signal for said knocking signal in said controlling step in response to said control signal. 10. A method as in claim 9 wherein: said method further comprises the step of determining a peak value of said knocking signal; and said fault signal generating step includes the step of generating said fault signal when said peak value is beyond a predetermined threshold. 11. A method as in claim 9 or 10 wherein: said first and second operation signal generating step includes the step of detecting engine load, said second operation signal being an indication of high engine load; and said control signal generating step generates said control signal when said second operating signal indicates a high load. 12. A method of controlling ignition timing of an engine comprising: generating an operation signal related to an operating condition of said engine; generating a load signal when a load on said engine is high; generating a knocking signal related to knocking in said engine; controlling said ignition timing in response to said operation signal and said knocking signal; determining a peak value of said knocking signal; generating a fault signal when said peak value is beyond a predetermined threshold, indicative of inoperativeness of said knocking signal generating step; generating a dummy signal, said dummy having the effect of retarding said ignition timing to a timing at which knocking is unlikely to occur when said controlling step is responsive to said dummy signal; generating, in response to said load signal and said fault signal, a control signal when said engine load is high and said knocking signal generating step is inoperative; and substituting said dummy signal for said knocking signal in said controlling step in response to said control signal. 13. A method as in claim 8, 9 or 12, further comprising the step of informing an operator when said dummy signal is applied to said controlling means. 14. A method of controlling ignition timing of an engine comprising: generating an operation signal related to an operating condition of said engine; generating a resistance related to knocking in said engine; controlling said ignition timing in response to said operation signal and said resistance; applying a voltage across said knocking related resistance and a known resistance; generating a fault signal when a voltage between said knocking related resistance and said known resistance crosses a predetermined threshold indicative of said resistance generating step being inoperative; generating a dummy signal, said dummy having the effect of retarding said ignition timing to a timing at which knocking is unlikely to occur when said controlling step is responsive to said dummy signal; and substituting said dummy signal for said knocking signal in said controlling step in response to said fault signal. 15. A system for controlling ignition timing in an engine, comprising ignition pulse emitting means for emitting an ignition pulse in proportion to an engine rotating condition detected, knocking signal emitting means, including a knocking sensor, for emitting a knocking signal in response to knocking detected by said knocking sensor, an updown counter for downcounting an ignition pulse fed from said ignition pulse emitting means and up-counting a knocking signal pulse fed from said knocking signal emitting means, and an ignition timing calculation circuit for sending out an ignition pulse fed from said ignition pulse emitting means after delaying it by a value in proportion to a count value from said updown counter, wherein said system further comprises: a knocking sensor fault detecting circuit including a peak value holding circuit for holding a peak value of said knocking signal, an abnormality discriminating level setting circuit for generating a preset voltage signal, means for comparing said peak value with said preset voltage signal, wherein said knocking sensor fault detecting circuit sends out a signal indicating a fault of the knocking sensor when said peak value is lower than said preset voltage signal; engine load detecting means for sending out a signal when an engine load detected is higher than a preset value; an "AND" circuit for taking a logical product between an output signal fed from said knocking sensor fault detecting circuit and an output signal fed from said engine load detecting means; a dummy signal generating circuit for generating a dummy signal to set the ignition timing at a predetermined position on the delay side; and a switching circuit for switching from an output signal fed from said updown counter to a dummy signal fed from said dummy signal generating circuit and feeding the latter to said ignition timing calculation circuit in response to an output signal fed from said "AND" circuit.