Patent ID: 10458354

Abstract:
Provided is a knock detecting device capable of ensuring knock detection accuracy irrespective of fuel injection conditions even when a period during which injection-valve noise occurs overlaps with a knock determination period. An ECU 9 subjects signals output from a knock sensor, which detects vibrations of an internal combustion engine, to frequency analysis to calculate frequency components (501). The ECU 9 calculates a background level that indicates the average of the frequency components (503). The ECU 9 stores, in association with each other, the number of fuel injections, which indicates the number of fuel injections in a predetermined time period during one combustion cycle, with a learning value, which indicates a frequency-component correction amount (507). The ECU 9 determines the presence or absence of a knock (504) on the basis of a knock index, which indicates the ratio of the difference between each frequency component and the learning value corresponding to the number of fuel injections, to the background level (503).