| 摘要 |
PURPOSE:To permit the correct trouble detection of a knocking sensor independently of the operation state by forming the knocking sensor in piezoelectric type and varying the load impedance in accordance with the engine operation state quantity. CONSTITUTION:A microcomputer 1-5 divides a revolution speed range into four stages on the basis of the revolution information supplied from a wave form a shaping circuit 1-7, and the microcomputer 1-5 sends each stage into a revolution speed - resistance value conversion circuit 1-9 in two bit expression. Accordingly, the load resistance of a knocking sensor 1-1 varies, and when the number of revolution is low, sensitivity is large, and the output voltage is increased. Accordingly, in the low revolution speed range where the engine vibration is less, the output signal of the knocking sensor is held large, and the detection of trouble of the knocking sensor can be carried out correctly. |
