Abstract: An ignition system for a vehicle engine has a fast response knock control which generates a rectified knock sensor signal having peaks at a knock frequency in accordance with the knock induced engine vibrations and samples and holds the voltage at each consecutive peak to generate a knock burst envelope signal in which knock burst envelopes correspond in amplitude and duration to knock vibration bursts in the knock sensor signal without phase shift induced group delay. The fast response is preserved in a fast response DC noise reference and an output which provides pulses at a frequency increasing with amplitude of the knock burst envelopes.

Abstract: A dual slope drive-by-wire device circuit is used for controlling the position of the throttle of an engine. The circuit generates a command such that the response is a low gain for low values of throttle position for providing a desired resolution at low throttle angles such as idle, and a high gain for higher throttle angles, producing a desired range of throttle angle control. The throttle is positioned in response to the command signal.

Abstract: A low impedance interface circuit for use with an internal combustion engine between a capacitive piezoelectric combustion pressure sensor and LPP signal processing circuitry comprises an operational amplifier with a negative feedback capacitor and an input DC blocking capacitor, a voltage follower amplifier with a first resistor at its input and a second resistor at its output connecting it in parallel with the feedback capacitor, a DC filter capacitor connected to the input of the voltage follower amplifier and forming a low pass filter with the first resistor to maintain a substantially constant DC voltage equal to the DC operating voltage for DC feedback, a current source controlled by the output of the operational amplifier and connected in series with the first resistor to provide increased current for the charging of the DC filter capacitor and a diode bypassing the first resistor to allow fast charging of the DC filter capacitor and DC blocking capacitor during startup.

Abstract: A peak combustion pressure signal processing circuit for an internal combustion engine having a plurality of combustion chambers with combustion pressure sensors includes an operational amplifier for each sensor with an output connected through a diode to a common junction. Each operational amplifier has a feedback circuit from the common junction to its input effective to cause its output voltage to decrease so as to reverse bias its output diode when the voltage on the common junction exceeds the voltage derived from the associated sensor, whereby only the diode passing the maximum combustion pressure signal is forward biased. A logic circuit having inputs from the common junction and the outputs of at least all but one of the operational amplifiers determines which diode is forward biased and assumes a uniquely identifiable output state.

Abstract: A circuit for controlling and indicating the operation of an electromagnetic fuel injector is described in which the injector current is regulated to a predetermined value by switching the injector coil current on and off in response to the coil current value relative to the predetermined value. Operation of the injector is sensed by sensing the change in direction in the duty cycle of the switched coil current as the duty cycle varies while the injector armature moves toward and strikes its stop position.

Abstract: An exhaust gas recirculation control system variably controls the amount of exhaust gas recirculated to a diesel engine in accord with the quantity of fuel supplied per engine revolution between a maximum amount at a first predetermined quantity of fuel per revolution and a minimum amount at a second predetermined quantity of fuel per revolution. The system maintains a substantially constant relationship between the exhaust gas recirculation amount and the quantity of fuel injected for each revolution over the speed range of the engine even though the fuel control element positions providing the first and second predetermined values of fuel quantity per revolution each increases at different rates as a function of increasing engine speeds.

Abstract: A vibration sensor mounted on an internal combustion engine characterized by knock-induced vibrations at a characteristic frequency and by other vibrations is tuned to resonate at substantially the characteristic frequency. A bandpass filter tuned to the characteristic frequency is connected to the vibration sensor output; and the output of the filter is provided to one input of a comparator and to average detector circuitry for generating a unidirectional noise reference signal representing noise at the characteristic frequency, which signal is provided to the other input of the comparator. The knock signal, obtained from the output of the comparator and comprising pulses corresponding to knock-induced peaks of amplitude greater than the unidirectional noise reference signal, is fed back through a low-pass filter to the average detector circuitry in sense to oppose increases in the unidirectional noise reference signal during said knock-induced peaks.