Abstract: A vibration detecting apparatus comprises a housing having at one end thereof an opening, a piezoelectric element disposed within the housing, a connector mounted to the housing to cover the opening thereof and having an output pin, a lead wire for electrically connecting the piezoelectric element with the output pin, and an initially conical annular spring having an outer peripheral edge portion thereof received by an annular groove formed in an inner peripheral wall of the housing. The piezoelectric element is biased by the initially conical annular spring.

Abstract: A knocking detection apparatus for multi-cylinder engines, capable of detecting knocking through sensing pressure pulsation propagating through the cooling water flowing in a cylinder block surrounding the cylinders. The knocking detection apparatus has a diaphragm facing the space downstream from the detection apparatus as viewed in the direction of flow of the cooling water, and a transducer dixed to the diaphragm.

Abstract: In a knock detecting apparatus for an internal combustion engine, the output signal of a knock sensor whose output signal level varies in accordance with the engine conditions, engine speed, sensor sensitivity, etc., is passed through an automatic gain control circuit (AGC) thereby stabilizing the output level. The background noise level derived by integrating the output signal and the stabilized output signal are compared to detect the occurrence of knocking. The stabilized output signal is passed through a low-pass filter or a band-pass filter and the resulting control signal is used to control the gain of the AGC circuit.

Abstract: An engine knocking detection device has a diaphragm to be disposed in contact with the engine cooling water so as to resonate with pulsations of the pressure of the cooling water caused by engine knockings, and output elements responsive to the vibration of the diaphragm to produce an electrical output signal to be utilized for the control of engine spark timing. The water-contacting surface of the diaphragm is coated with a layer of a hydrophilic material operative to prevent attachment or adhesion of air bubbles to the water-contacting surface of the diaphragm whereby the sensitivity of the diaphragm to the water pressure pulsation is improved.

Abstract: A diagnostic apparatus for an internal combustion engine ignition system measures the rise of the secondary voltage at the ignition coil represented by time lapse between initiation of the secondary voltage rising and occurrence of break and the ignition coil primary breaking current value. Results of the measurement are computed to determine stray capacitance existing in the internal combustion engine ignition system and secondary voltage.

Abstract: An ignition system for internal combustion engine, which controls the ignition coil primary current according to the magnitude of the floating capacitance in the secondary side wiring section of the ignition coil, by determining the floating capacitance from the negative slope of rising of the secondary voltage produced in the ignition coil in response to the cutoff of the primary current and the primary cutoff current value, the slope being determined by measuring the period T until the secondary voltage reaches a predetermined voltage value. When the floating capacitance is increased, the primary cutoff current value is increased to increase the coil energy so as to increase the secondary voltage generated in the ignition coil for preventing the generation of a miss-spark.