Electronic engine control apparatus having arrangement for detecting stopping of the engine

• US 4,312,038 A
• Filed: 10/18/1978
• Issued: 01/19/1982
• Est. Priority Date: 10/19/1977
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Furuhashi, Toshio, Takato, Masao, Imai, Masumi
• Primary Examiner(s): Gruber, Felix D.
• Application Number:
  US05/952,531
• Time in Patent Office: 1,189 Days
• Field of Search: 364/424, 364/431, 364/442, 123/440, 123/480, 123/486, 123/491, 123/492, 123/493, 371/62
• US Class Current: 701/115
• CPC Class Codes: F02D 41/042 for stopping the engine
• CPC Class Codes: F02D 41/062 for starting F02D41/061 takes precedence
• CPC Class Codes: F02D 41/26 using computer, e.g. microprocessor

Abstract

An electronic engine control apparatus controls the engine on a basis of the outputs of the digital processor which arithmetically processes output signals from plural sensors for detecting the operating conditions of the engine. Whether or not a pulse to be generated in timing with the rotation of the engine has been generated within a preset period of time, as specified by the digital processor, is checked. If the pulse is generated, a timer for measuring the preset period is cleared. If the pulse is not generated within the preset period, a signal indicating the stopping of the engine is generated, whereby an interrupt signal is generated to cause the digital processor to process the interrupt.

Claims

1. For use in a processor-controlled apparatus for controlling the operation of an internal combustion engine for which sensor means produce signals representative of operating conditions of said engine, and being coupled to actuator means for controlling respective energy conversion functions of said engine in response to control signals applied thereto, a control apparatus comprising, in combination:

first means for generating an engine control timing signal pattern through which operational events of said engine are controlled;

second means for storing a plurality of engine control codes supplied thereto by said processor;

third means, coupled to said first means, for generating respective engine timing codes the values of which are selectively modified by said engine control timing pattern;

fourth means, coupled to said second and third means, for comparing respective ones of said engine control codes with respective ones of said engine timing codes and producing respective output signals when said respective engine control codes define a prescribed relationship with respect to said engine timing codes; and

fifth means, coupled to said fourth means, for producing control signals to be coupled to said actuator means in response to the output signals produced by said fourth means; and

wherein

one of said engine control codes as supplied to said second means by said processor is representative of a prescribed rate of rotation of the engine crankshaft; and

wherein said control apparatus further comprises

sixth means, responsive to an output signal produced by said fourth means in response to a respective enging timing code generated by said third means defining said prescribed relationship with respect to said one engine control code, for preventing said fifth means from coupling control signals to said actuator means.

2. A control apparatus according to claim 1, wherein said sixth means includes means for preventing engine timing codes generated by said third means for being modified by said engine control timing pattern.

3. A control apparatus according to claim 2, wherein said sixth means further includes

means, responsive to an output signal produced by said fourth means, for producing a prescribed interrupt signal to be selectively coupled to said processor, and

means, adapted to be coupled to said processor, for storing prescribed data, coupled thereto from said processor in response to said interrupt signal, in accordance with which engine time codes generated by said third means are prevented from being modified by said engine control timing pattern.

4. A control apparatus according to claim 3, wherein said control apparatus further includes seventh means, responsive to said prescribed data, for causing the values of the engine timing codes generated by said third means to be set at preselected valves.

5. A control apparatus according to claim 4, wherein

said sensor means include rotation sensor means for generating an output pulse in response to the rotation of the engine crankshaft through a predetermined angle of rotation,

a second of said engine control codes is representative of a prescribed angle of rotation of the engine crankshaft, relative to a preselected rotational position of said crankshaft, for which said rotation sensor means produces an output pulse, and

said control apparatus further includes eighth means, responsive to an output signal produced by said fourth means in response to a respective engine timing code generated by said third means defining said prescribed relationship with respect to said second engine control code, for causing the value of the engine timing code associated with said one engine control code to be set at a prescribed value.

6. A control apparatus according to claim 5, wherein said eighth means includes means for synchronizing the setting of the value of the engine timing code associated with said one engine control code at said prescribed value with the signals of said engine control timing signal pattern by way of which the engine timing code associated with said one engine control code is modified.

7. A control apparatus according to claim 3, wherein the values of the respective engine control codes are set at code values for restarting the engine by said processor in response to said interrupt signal.

8. A control apparatus according to claim 1, wherein said prescribed rate of rotation of the engine crankshaft corresponds to a condition indicative of the stopping of the engine.

9. A control apparatus according to claim 1, wherein said sixth means includes

means, responsive to said output signal produced by said fourth means, for producing a prescribed interrupt signal to be selectively coupled to said processor, and

means, adapted to be coupled to said processor, for storing prescribed data coupled thereto from said processor in response to said interrupt signal in accordance with which said fifth means is prevented from coupling control signals to said actuator means.

10. A control apparatus according to claim 1, wherein said control apparatus further includes seventh means, responsive to said sixth means preventing said fifth means from coupling signals to said actuator means, for causing the values of the engine timing codes generated by said third means to be set at preselected values.

11. A control apparatus according to claim 1, wherein

said sensor means include rotation sensor means for generating an output pulse in response to the rotation of the engine crankshaft through a predetermined angle of rotation,

a second of said engine control codes is representative of a prescribed angle of rotation of said engine crankshaft, relative to a preselected rotational position of said crankshaft, for which said rotation sensor means produces an output pulse, and

said control apparatus further includes seventh means, responsive to an output signal produced by said fourth means in response to a respective engine timing code generated by said third means defining said prescribed relationship with respect to said second engine control code, for causing the value of the engine timing code associated with said one engine control code to be set at a prescribed value.

12. A control apparatus according to claim 1, wherein the values of said respective engine control codes are set at code values for restarting the engine in response to an output of said sixth means.

13. A control apparatus according to claim 1, wherein

said second means comprises a first plurality of registers for storing respective engine control codes, and

said third means includes a second plurality of registers for storing respective engine timing codes, and means, coupled to said second plurality of registers, for controllably modifying the engine timing codes in accordance with the signals of said engine control timing signal pattern.

14. A control apparatus according to claim 13, wherein said controllably modifying means comprises

means for selectively incrementing the data value of a respective engine timing code by a prescribed value in response to receipt of a respective portion of said engine control timing signal pattern that is associated with that engine timing code.

15. A control apparatus according to claim 14, wherein said incrementing means comprises

means for temporarily storing the engine timing code stored by each respective one of said second plurality of registers, and

means for receiving the engine timing code from said temporarily storing means and selectively incrementing the data value of said code and causing the engine timing code stored in said respective one of said secone plurality of registers to be replaced by said code the data value of which has been selectively incremented.

16. A control apparatus according to claim 14, wherein said incrementing means comprises

means for reading out the engine timing code stored by each respective one of said second plurality of registers and temporarily storing said read-out engine timing code during a first interval of time, and

means for receiving the engine timing code from said temporarily storing means and selectively incrementing the data value of said code and causing the engine timing code stored in said respective one of said second plurality of register to be replaced by said code the data value of which has been selectively incremented during a second interval of time subsequent to said first interval of time.

17. A control apparatus according to claim 13, wherein said fifth means includes

a first plurality of storage means for selectively storing the respective output signals produced by said fourth means;

and

a second plurality of storage means, coupled to the respective ones of said first plurality of storage means, for receiving and storing the output signals stored by said first plurality of storage means.

18. A control apparatus according to claim 17, wherein said controllably modifying means includes means, coupled to said fifth means, for controllably modifying the engine timing codes stored in said second plurality of registers in dependence upon the output signals stored said second plurality of storage means.

19. A control apparatus according to claim 13, wherein said controllably modifying means includes means, coupled to said fifth means, for controllably modifying the engine timing codes stored in said second plurality of registers in dependence upon the output signals stored said second plurality of storage means.

20. A control apparatus according to claim 13, wherein said control apparatus further includes seventh means, responsive to said sixth means preventing said fifth means from coupling control signals to said actuator means, for causing the values of engine timing codes stored by said second plurality of registers to be set at preselected values.

21. A control apparatus according to claim 13, wherein

said sensor means include rotation sensor means for generating an output pulse in response to the rotation of the engine crankshaft, relative to a preselected rotational position of said crankshaft, for which said rotation sensor means produces an output pulse, and

said control apparatus further includes seventh means, responsive to an output signal produced by said fourth means in response to a respective engine timing code stored by one of said second plurality of registers defining said prescribed relationship with respect to said second engine control code, for causing the value of the engine timing code associated with said one engine control code to be set at a prescribed value.

22. A control apparatus according to claim 13, wherein said sixth means further includes

means, responsive to said output signal produced by said fourth means, for producing a prescribed interrupt signal to be selectively coupled to said processor, and

means adapted to be coupled to said processor, for storing prescribed data, coupled thereto from said processor in response to said interrupt signal, in accordance with which engine time codes stored by said second plurality of registers are prevented from being modified by said engine control timing pattern.

23. A control apparatus according to claim 22, wherein said control apparatus further includes seventh means, responsive to said prescribed data, for causing the values of the engine timing codes stored by said second plurality of registers to be set at preselected values.

24. A control apparatus according to claim 23, wherein

said sensor means include rotation sensor means for generating an output pulse in response to the rotation of the engine crankshaft through a predetermined angle of rotation,

a second of said engine control codes stored by a register of first plurality of registers is representative of a prescribed angle of rotation of the engine crankshaft, relative to a preselected rotational position of said crankshaft, for which said rotation sensor means produces an output pulse, and

said control apparatus further includes eighth means, responsive to an output signal produced by said fourth means in response to a respective engine timing code generated by said third means defining said prescribed relationship with respect to said second engine control code, for causing the value of the engine timing code associated with said one engine control code to be set at a prescribed value.

25. A control apparatus according to claim 24, wherein said eighth means includes means for synchronizing the setting of the value of the engine timing code associated with said one engine control code at said prescribed value with the signals of said engine control timing signal pattern by way of which the engine timing code associated with said one engine control code is modified.

26. For use in a processor-controlled apparatus for controlling the operations of an internal combustion engine for which a plurality of sensors detect operating conditions of the engine, and being coupled to actuators for controlling respective energy conversion functions of said engine, a control apparatus for generating pulses for driving said actuators in accordance with the engine control data generated by said processor, said actuators controlling the energy conversion functions of said engine in accordance with the pulses delivered from said control apparatus, comprising, in combination:

first and second registers for storing respective data corresponding to fuel injection and ignition;

a first counter for counting first pulses generated at regular intervals;

a second counter for counting second pulses generated in timing with the rotation of said engine;

comparing means for comparing the contents of said first and second registers with the contents of said first and second counters and outputting first and second output signals representative of the results of comparison, respectively;

first and second storage means for storing said first and second output signals;

a set signal generator for generating set signals for coupling said first and second output signals to said first and second storage means respectively, said actuators being controlled in accordance with the contents of said first and second storage means;

means for producing sequential timing pulses;

means for storing a count whose value is successively modified by said sequential timing pulses;

means for loading and storing a selected reference value supplied thereto by said processor;

means for detecting stopping of the engine in response to the value of said count reaching said selected reference value as supplied by said processor; and

means for inhibiting said set signal generator from coupling said set signals to said storage means in response to the detection of the stopping of the engine by the engine stopping detecting means.

27. A control apparatus according to claim 26, wherein said inhibiting means inhibits the application of said first and second pulses to said first and second counters, in response to the detection of stopping of the engine.

28. A control apparatus according to claim 27, wherein said inhibiting means includes first and second inhibit circuits for inhibiting the application of said first and second pulses to said first and second counters in response to the detection of stopping of the engine, respectively.

29. A control apparatus according to claim 27, wherein said inhibiting means includes a mode register for inhibiting said set signal and said first and second output signals from being coupled to said storage means and said first and second counters, respectively, in response to first prescribed data supplied from said processor, and for enabling said set signal and said first and second output signals to be coupled to said storage means and said first and second counters, respectively, in response to second prescribed data supplied from said processor, said processor delivering said first prescribed data to said mode register in response to the detection of stopping of the engine by said engine stopping detecting means.

30. A control apparatus as claimed in claim 29, wherein said processor returns its data processing operations to their initial states after the supply of said first prescribed data to said mode register.

31. A control apparatus according to claim, 30, wherein said processor supplies said second prescribed data to said mode register after the returning said data processing operations to said initial states.

32. For use in a processor-controlled apparatus for controlling the operation of a combustion engine having an output crankshaft driven by mechanical energy converted from heat energy which is released by the combustion of fuel, said engine including at least ignition means for controlling the ignition timing of said engine, in response to control signals coupled thereto, and being coupled to receive signals of said engine, produced by a plurality of sensors indicative of operating conditions of the engine, said sensors including at least an angle sensor for producing an output signal in response to a predetermined angle of rotation of the crankshaft, a control apparatus comprising, in combination:

first means for producing output signals at predetermined time intervals;

second means for counting the output signals produced by said first means;

third means for loading and storing a selectable reference count value supplied thereto by said processor;

fourth means for producing an output dependent upon a selectable degree of rotation of the crankshaft relative to its position at which an output is produced by said angle sensor;

fifth means, coupled to said fourth means, for returning the count total of said second means to its initial value in response to the output of said fourth means;

sixth means for supplying an output to be coupled to said processor means in response to the counted value of said second means reaching said selectable reference count stored by said third means value; and

seventh means, adapted to be coupled to receive data from said processor means in accordance with the output of the sixth means, and preventing control signals from being delivered to said ignition means.

33. A control apparatus according to claim 32, wherein said fifth means is further coupled with said processor for further returning the count total of said second means to its initial value in response to the output of the processor.

34. For use in a processor-controlled apparatus for controlling the operation of a combustion engine having an output crankshaft driven by mechanical energy converted from heat energy which is released by the combustion of fuel, said engine including at least ignition means for controlling the ignition timing of said engine, in response to control signals applied thereto, and being coupled to receive signals produced by a plurality of sensors indicative of operating conditions of the engine, said sensors including at least an angle sensor for producing an output signal in response to a predetermined angle of rotation of the output crankshaft, a control apparatus comprising, in combination:

first means for producing a respective first or a second signal in accordance with data coupled thereto from said processor;

second means for producing signals of a predetermined time interval in response to said first signal produced by said first means and terminating said signals in response to said second signal produced by said first means;

third means for counting the output signals produced by said second means,

fourth means for loading and storing a selectable reference count value supplied thereto by said processor;

fifth means for producing an output dependent upon a selectable degree of rotation of said output crankshaft relative to its position at which an output is produced by said angle sensor;

sixth means for resetting the counted total of said third means to its initial value in response to the output of said fifth means;

seventh means for delivering an output to the processor when the counted value of said third means reaches said selectable reference count stored by said fourth means and

eighth means adapted to be coupled to receive data produced by the processor in accordance with the output of the seventh means, said eighth means preventing control signals from being delivered to said ignition means.

35. A control apparatus according to claim 34, wherein said sixth means is further adapted to be coupled with said processor to return the count total of said third means to its initial value in accordance with the output of the processor.

36. A method of operating a processor-controlled apparatus for controlling the operation of a combustion engine, said engine including an output crankshaft driven by mechanical energy converted from heat energy caused by the combustion of a fuel, and at least ignition means for controlling energy conversion, in response to control signals applied thereto, and being coupled to receive signals produced by a plurality of sensors indicative of operating conditions of the engine, said sensors including an angle sensor for producing an output in accordance with a predetermined angle of rotation of the output crankshaft of the engine, said apparatus including input/output means adapted to receive sensed signals from said sensors and to deliver control signals to said energy conversion controlling means;

38. A method according to claim 36, wherein said method further includes the step of

(h) returning the count value to its initial value in response to the signal produced by step (f).

40. A method according to claim 36, wherein said method further includes the steps of

(h) storing a first and a second signal to control the count;

and

(i) starting the count in accordance with the first signal stored in step (h), and stopping the count in accordance with the second signal stored in step (h).

42. A method according to claim 40, wherein said method further includes the step of

(g) setting initial control signal values into the input/output means after execution of step (f).

44. A method according to claim 40, wherein said method further includes the step of

(h) preventing control signals from being delivered from said input/output means to said energy conversion control means, in response to the signal produced by step (f).

37. the method comprising the steps of:

(a) loading, in reference storage means, a selectable reference count value;

(b) producing a signal at predetermined time intervals;

(c) advancing a count in response to said signals;

(d) restarting said count in response to the output of the angle sensor;

(e) continuously repeating the sequence of steps (b) through (d);

(f) producing a signal when the count total reaches said selectable count value; and

(g) preventing control signals from being delivered from the input/output means to said ignition means in response to the signal produced in step (f).

39. A method according to claim 37, wherein said method further includes the step of

(i) storing a first and a second signal to control the count;

and

(j) strating the count in accordance with the first signal stored in step (i) and for stopping the count in accordance with the second signal stored in step (i).

41. A method of operating a processor-controlled apparatus for controlling the operation of a combustion engine, said engine including an output crankshaft driven by mechanical energy converted from heat energy caused by the combustion of a fuel, and at least one means controlling energy conversion in response to control signals applied thereto, and being coupled to receive signals produced by a plurality of sensors indicative of operating conditions of the engine, said sensors including an angle sensor for producing an output signal in accordance with a predetermined rotation of the output crankshaft of the engine, said apparatus including input/output means adapted to receive sensed signals from said sensors and to deliver control signals to said energy conversion controlling means;

the method comprising the steps of;

(a) loading, in reference storage means, a selectable count value;

(b) producing signals at predetermined time intervals;

(c) advancing a count in response to said signals;

(d) returning the count value to an initial value in response to an output of the angle sensor;

(e) continuously repeating the sequence of steps (b) through (d);

(f) producing a signal when the count total reaches said selectable count value; and

(g) returning engine control data processing operations to their initial states in response to the signal produced by step (f).

43. A method according to claim 41, wherein said method further includes the step of

(i) preventing control signals from being delivered from said input/output means to said energy conversion control means in response to the signal produced by step (f).

45. For use in a processor-controlled apparatus for controlling the operation of an internal combustion engine, having an output crankshaft, for which sensor means produce signals representative of operating conditions of said engine, said sensor means including an angle sensor for producing an output signal in response to a predetermined angle of rotation of the output crankshaft, and being coupled to actuator means for controlling respective energy conversion functions of said engine in response to control signals applied thereto, a control apparatus comprising, in combination:

first means for generating an engine control timing signal pattern through which operational events of said engine are controlled;

second means for storing a plurality of engine control codes;

third means, coupled to said first means, for generating respective engine timing codes the values of which are selectively modified by said engine control timing pattern;

fourth means, coupled to said second and third means, for comparing respective ones of said engine control codes with respective ones of said engine timing codes and producing respective output signals when said respective engine control codes define a prescribed relationship with respect to said engine timing codes; and

fifth means, coupled to said fourth means, for producing control signals to be coupled to said actuator means in response to the output signals produced by said fourth means; and

wherein

one of said engine control codes is representative of a prescribed rate of rotation of the engine crankshaft, and a second of said engine control codes is representative of a prescribed degree of rotation of said crankshaft relative to its position at which said angle sensor produces an output; and

wherein said control apparatus further comprises

sixth means, responsive to an output signal produced by said fourth means in response to a respective engine timing code generated by said third means defining said prescribed relationship with respect to said one engine control code, for preventing said fifth means from coupling control signals to said actuator means; and

seventh means, responsive to an output signal produced by said fourth means in response to a respective engine timing code generated by said third means defining said prescribed relationship with respect to said second engine control code, for preventing the respective engine timing code generated by said third means that is associated with said one engine control code from defining said prescribed relationship with respect to said one engine control code.

46. For use in a processor-controlled apparatus for controlling the operations of an internal combustion engine, having an output crankshaft, for which a plurality of sensors detect operating conditions of the engine, said sensors including an angle sensor for producing an output pulse in response to a predetermined angle of rotation of the crankshaft, and being coupled to actuators for controlling respective energy conversion functions of said engine, a control apparatus for generating pulses for driving said actuators in accordance with the engine control data generated by said processor, said actuators controlling the energy conversion functions of said engine in accordance with the pulses delivered from said control apparatus, comprising, in combination:

first and second registers for storing respective data corresponding to fuel injection and ignition;

a first counter for counting first pulses generated at regular intervals;

a second counter for counting second pulses generated in timing with the rotation of said engine;

comparing means for comparing the contents of said first and second registers with the contents of said first and second counters and outputting first and second output signals representative of the results of comparison, respectively;

first and second storage means for storing said first and second output signals;

a set signal generator for generating set signals for coupling said first and second output signals to said first and second storage means respectively, said actuators being controlled in accordance with the contents of said first and second storage means;

means for detecting stopping of the engine;

means for inhibiting said set signal generator from coupling said set signals to said storage means in response to the detection of the stopping of the engine by the engine stopping detecting means; and

means for producing an output dependent upon a selectable degree of rotation of the crankshaft relative to its position at which an output is produced by said angle sensor, and thereby preventing said detecting means for detecting the stopping of the engine.

47. For use in a processor-controlled apparatus for controlling the operation of a combustion engine having an output crankshaft driven by mechanical energy converted from heat energy which is released by the combustion of fuel, said engine including at least ignition means for controlling the ignition timing of said engine, in response to control signals coupled thereto, and being coupled to receive signals of said engine, produced by a plurality of sensors indicative of operating conditions of the engine, said sensors including at least an angle sensor for producing an output signal in response to a predetermined angle of rotation of the crankshaft, a control apparatus comprising, in combination:

first means for producing output signals at predetermined time intervals;

second means for counting the output signals produced by said first means;

third means for producing an output dependent upon a selectable degree of rotation of the crankshaft relative to its position at which an output is produced by said angle sensor;

fourth means, coupled to said third means, for returning the count total of said second means to its initial value in response to the output of said third means;

fifth means for supplying an output to be coupled to said processor in response to the counted value of said second means reaching a predetermined value; and

sixth means, adapted to be coupled to receive data from said processor means in accordance with the output of the fifth means, and preventing control signals from being delivered to said ignition means.

48. For use in a processor-controlled apparatus for controlling the operation of a combustion engine having an output crankshaft driven by mechanical energy converted from heat energy which is released by the combustion of fuel, said engine including at least ignition means for controlling the ignition timing of said engine, in response to control signals applied thereto, and being coupled to receive signals produced by a plurality of sensors indicative of operating conditions of the engine, said sensors including at least an angle sensor for producing an output signal in response to a predetermined angle of rotation of the output crankshaft, a control apparatus comprising, in combination:

first means for producing a respective first or a second signal in accordance with data coupled thereto from said processor;

second means for producing signals of a predetermined time interval in response to said first signal produced by said first means and terminating said signals in response to said second signal produced by said first means;

third means for counting the output signals produced by said second means;

fourth means for producing an output dependent upon a selectable degree of rotation of said output crankshaft relative to its position at which an output is produced by said angle sensor;

fifth means for resetting the counted total of said third means to its initial value in response to the output of said fourth means;

sixth means for delivering an output to the processor when the counted value of said third means reaches a predetermined value; and

seventh means adapted to be coupled to receive data produced by the processor in accordance with the output of the sixth means, said seventh means preventing control signals from being delivered to said ignition means.

49. For use in a processor-controlled apparatus for controlling the operation of a combustion engine having an output crankshaft driven by mechanical energy converted from heat energy which is released by the combustion of fuel, said engine including at least ignition means for controlling the ignition timing of said engine, in response to control signals coupled thereto, and being coupled to receive signals of said engine, produced by a plurality of sensors indicative of operating conditions of the engine, said sensors including at least an angle sensor for producing an output signal in response to a predetermined angle of rotation of the crankshaft, a control apparatus comprising, in combination:

first means for producing output signals at predetermined time intervals;

second means for counting the output signals produced by said first means;

third means for loading and storing a selectable reference count supplied thereto by said processor;

fourth means for returning the count total of said second means to its initial value in response to the output of said angle sensor;

fifth means for supplying an output to be coupled to said processor means in response to the counted value of said second means reaching said selectable reference count stored by said third means; and

sixth means, adapted to be coupled to receive data from said processor in accordance with the output of the fifth means, and preventing control signals from being delivered to said ignition means.

50. For use in a processor-controlled apparatus for controlling the operation of a combustion engine having an output crankshaft driven by mechanical energy converted from heat energy which is released by the combustion of fuel, said engine including at least ignition means for controlling the ignition timing of said engine, in response to control signals applied thereto, and being coupled to receive signals produced by a plurality of sensors indicative of operating conditions of the engine, said sensors including at least an angle sensor for producing an output signal in response to a predetermined angle of rotation of the output crankshaft, a control apparatus comprising, in combination:

first means for producing a respective first or a second signal in accordance with data coupled thereto from said processor;

second means for producing signals of a predetermined time interval in response to said first signal produced by said first means and terminating said signals in response to said second signal produced by said first means;

third means for counting the output signals produced by said second means;

fourth means for loading and storing a selectable reference count value supplied thereto by said processor;

fifth means for resetting the counted total of said third means to its initial value in response to the output of said sensor;

sixth means for delivering an output to the processor when the counted value of said third means reaches said selectable reference count stored by said fourth means; and

seventh means adapted to be coupled to receive data produced by the processor in accordance with the output of the sixth means, said seventh means preventing control signals from being delivered to said ignition means.