Ignition timing and detonation controller for internal combustion engine ignition system

In an alternator drive capacitor discharge system for an internal combustion engine having capacitor means, and an alternator including first coil means for providing electrical pulses for charging said capacitor means, said electrical pulses having a frequency related to engine speed, and second coil means for providing a biasing signal for regulating the timing of the discharge of said capacitor means and tending to effect timing advance as engine speed increases, the improvement comprising:

• means responsive to the frequency of said electrical pulses for modifying said biasing signal so as to effect additional timing advance when engine speed exceeds a predetermined speed, said means responsive to the frequency of said electrical pulses including a phase-shifting circuit for providing phase-shifted signals based on said pulses, an advance timer circuit and a retard timer circuit for receiving said phase-shifted signals and for providing timer output signals based therein, a control gate circuit for receiving said timer output signals and for providing a gate signal based thereon, and an ignition bias control circuit for receiving said gate signal and a timer output signal from said retard timer and for providing a bias control signal for modifying said biasing signal;
• and means responsive to engine detonation for further modifying said biasing signal so as to effect a reduction of said additional timing advance when detonation exceeds a predetermined level.

In an alternator driven capacitor discharge system for an internal combustion engine having capacitor means, and an alternator including first coil means for providing electrical pulses for charging said capacitor means, said electrical pulses having a frequency related to engine speed, and second coil means for providing a biasing signal to a first timing circuit for regulating the timing of the discharge of said capacitor means and tending to effect timing advance as engine speed increases, the improvement comprising:

• first means responsive to the frequency of said electrical pulses from said first coil means to provide a bias voltage to said first timing circuit to modify said biasing signal so as to effect additional timing advance when engine speed exceeds a predetermined speed;
• and second means responsive to engine detonation for providing a control signal to modify said bias voltage so as to effect a reduction of said additional timing advance when detonation exceeds a predetermined level;
• said first means comprising:
• an ignition bias control circuit for applying said bias voltage to said first timing circuit,
• a phase shifter circuit for receiving said electrical pulses from said first coil means and for providing a pair of phase-shifted pulsed signals;
• an advance timer circuit and a retard timer circuit for operating said ignition bias control circuit, each advance and retard timer circuit including a monostable multivibrator, and each advance and retard timer circuit receiving said pair of phase-shifted pulsed signals, each advance and retard timer circuit providing timer output signals for operating said ignition bias control circuit to cause the latter to advance or retard timing,
• said advance timer circuit operating to initiate an advance timer output signal in proportion to engine speed increase when the period of said electrical pulses from said first coil means equals the pulse width of the signals of said advance monostable multivibrator and until said period reaches half said pulse width and maximum spark advance occurs;
• said retard timer circuit operating to initiate a retard timer output signal in proportion to further engine speed increase when the period of said electrical pulses from said first coil means equals the pulse width of the signals of said retard monostable multivibrator and until said period reaches half said pulse width and spark advance has returned to its initial starting point;
• said second means comprising:
• a detonation sensing circuit for providing said control signal to said ignition bias control circuit for reducing said bias voltage from said ignition bias control circuit in proportion to increases in engine detonation sensed thereby;
• said detonation sensing circuit being responsive to the timer output signal of said retard timer circuit so that said control signal must increase in value in order to effect reduction of spark advance, thereby preventing high speed noise of said engine from effecting production of a spurious control signal by said detonation sensing circuit.

An ignition timing and detonation controller for use in an alternator driven capacitor discharge system for an internal combustion engine which comprises capacitor means, and an alternator including first coil means for providing electrical pulses for charging said capacitor means, said pulses having a frequency related to engine speed, and second coil means for providing a bias signal for regulating the timing of the discharge of said capacitor means, said biasing signal tending to effect timing advance as engine speed increases;

• said controller comprising:
• a spark advance circuit;
• and a detonation sensing circuit;
• said spark advance circuit comprising a spark advance timer to improve engine efficiency at cruising speed and a retard timer to insure proper high speed operation of said ignition system and said detonation sensing circuit;
• said timers being triggered by a trigger pulse representative of engine speed;
• said controller operating so that spark advance is initiated when the duty cycle of said advance timer is equal to the period of said trigger pulse;
• said spark advance remaining proportional to engine speed until the duty cycle of said advance timer is double the period of said trigger pulse, whereupon maximum spark advance is reached;
• said controller further operating so that further increase in engine speed produces no change in spark timing until the duty cycle of said retard timer is equal to the period of said trigger pulse, whereupon an increase in engine speed produces a proportional decrease in spark advance until the duty cycle of said retard timer is double that of the period of the trigger pulse whereupon spark timing is back to where spark advance was initiated and a further increase in engine speed produces no further change in spark timing;
• said detonation sensing circuit operating to proportionally reduce the spark advance towards the initial timing in direct proportion to the amplitude of detonation.