| 摘要 |
PURPOSE:To prevent the deterioration of a running property in a high-speed revolution zone by a method wherein the operation of a fail-safe circuit, detecting that a knocking sensor is abnormal, is stopped when the revolving number of an engine has exceeded a predetermined revolving number. CONSTITUTION:When the revolving number of the engine has exceeded 4,500rpm, a terminal S18 becomes low level and a transistor 119 is put OFF while another transistor 120 is put ON. As a result, the circuits of resistors 121, 122 are short- circuited and the potential of the negative terminal of an operational amplifier OP12 reduces by a redetermined amount. At this moment, the series circuit of the diode 123 and the resistor 124 is short-circuited, therefore, the transistor 125 is put OFF. As a result, a voltage is impressed to resistors R60, R61 from an electric source S2 through the resistor 126, therefore, the transistors T6, T4 are put ON. According to this method, the transistor T7 will never be put ON even if a fail-safe signal has been developed on the terminal S20 and, accordingly, the fail-safe function may be stopped practically. |
