Abstract: A knock control system which includes a knock control unit constructed of a transducer portion for detecting vibrations of an engine and converting the detected vibrations into an electric signal, and a knock signal processing unit for delivering a signal indicative of the occurrence of a knock in dependence upon a receipt of the knock signal from the transducer portion. The knock signal processing circuit controls the ignition timing of the internal combustion engine on the basis of the knock signal from the knock control unit. At least one of the transducer portion and the knock signal processing circuit unit of the knock control system is mounted on a portion of a distributor which has a fixing base portion at a part of the housing thereof.

Abstract: A knock control apparatus equipped with an altitude compensation function is disclosed. The apparatus comprises a knock sensor fitted to an internal combustion engine and detecting the mechanical oscillation of the engine; a background signal detection circuit discriminating the background level signal of the knock signal from the output signal of the knock sensor; a comparator for comparing the output signal of the knock sensor with the background signal and detecting knock and the intensity of knock; and a knock control circuit sequentially advancing the ignition timing of the internal combustion engine towards the maximum advance angle position and retarding the ignition timing in accordance with the occurrence of knock and its intensity so as to control and optimize the ignition timing of the engine.

Abstract: An ignition retard angle control apparatus for an internal combustion engine is disclosed.