Patent GB-1472984-A (GB)
Title: Spark timing control device for an internal combustion engine ignition system
IPC: F02P5/155
Filed: 1974-06-27
Abstract: 1472984 Timing ignition; ignition systems NISSAN MOTOR CO Ltd and HITACHI Ltd 27 June 1974 [30 June 1973] 28618/74 Heading F1B An ignition timing control device for an internal combustion engine comprises throttle velocity signal generating means for generating a signal representative of the velocity of throttle movement, first means for producing a first signal when the throttle velocity signal exceeds a positive predetermined level, second means for producing a second signal when the throttle velocity signal falls below a negative predetermined level, third means for producing a third signal when the engine speed falls below a predetermined value and fourth means for performing ignition timing advance control when it receives the first signal and when it receives the second signal in the absence of the third signal. The throttle velocity signal generating means comprises a throttle movement sensor 10 for producing an output voltage proportional to angular displacement of the throttle valve and a differentiating circuit 12 for differentiating the output voltage from the throttle movement sensor 10 with respect to time so as to produce the throttle velocity signal. The first means comprises first comparing means 18 for producing a first signal S1 when it receives a voltage higher than the predetermined positive level. A polarity, discriminating means 14 applies the throttle velocity signal to the first comparing means 18 when the throttle velocity signal is positive. The second means comprises second comparing means 22 for producing the second signal S2 when it receives a voltage smaller than the negative predetermined level. The second comparing means comprises a sign inverter 20 for inverting the sign of the throttle velocity signal. The third means comprises a voltage generating means 26 for producing a voltage proportional to the engine speed and third comparing means 28 responsive to the output of the voltage generating means for producing a signal S3 when the voltage proportional to engine speed falls below a predetermined value. The fourth means comprises an OR gate 30 responsive to the first and third signals for  producing a fourth signal S4 when at least one of the first and the third signals is provided, a memory circuit 32 responsive to the second and fourth signals for producing a fifth signal S5 when triggered by the second signal S2 until the appearance of the fourth signal S4 and an advance control circuit 34 responsive to the first signal, the fifth signal and an ignition timing signal St for performing an advance control. As shown a waveform modifying circuit 16 is employed. This circuit may be located between the first comparator 18 and the OR gate 30. The sign inverter 20 which has been shown connected between the polarity discriminator circuit 14 and the second comparator 22 may be connected between the comparator 22 and the memory circuit 32. Alternatively the sign inverter 20 may be connected between the polarity discriminator 14 and the waveform modifying circuit 16. Detailed circuit diagrams of components shown in the block diagram are included in the Specification.