PURPOSE: To detect the presence of the knocking statistically and precisely by extracting and storing the output in a predetermined section in the vicinity of an upper dead point among the detecting signals of the vibration of the engine, and displaying the result of the specific operation.
CONSTITUTION: The vibration generated by the combustion phenomenon of an internal combustion engine is detected, the output of a predetermined section in the vicinity of an upper dead point among the detecting signals is extracted, stored by predetermined times, and an average value for each air cylinder is obtained. further, the ratio of the data more than the predetermined times is computed as frequency for air cylinder with respect to this each average value, the average value of these values by the number of the air cylinders is computed as the whole air cylinder frequency, the result is displayed. For example, indicating pressure detecting devices 1aW1d comprising piezo-electric element, for example, is attached as a washer of an ignition plug of the respective air cylinders, and by using the circuit as illustrated in the figure, the result carrying out the predetermined operation in a frequency operating circuit 10 including a microcomputer is displayed digitally in the display circuit 12.
NOHIRA HIDETAKA
YOSHIMURA KUNIMASA
TOYOTA MOTOR CO LTD