| 摘要 |
PURPOSE:To prevent excessive increase of the temperature of the oxygen sensor for detecting the exhaust component and increase its durability by controlling with the aid of hysteresis, the current supply to the heater installed on the sensor according to the temperature of the sensor. CONSTITUTION:The oxygen sensor 11 arranged in the exhaust system of an internal combustion engine is equipped with a heater 12 for increasing its activity. The heater 12 is connected to the switch 13 having an normally-opened contact 13a, and at the same time the coil 13b of the switch 13 is connected to a key switch 15a and the temperature detector 15 to which the signal of the temperature sensor 16 arranged on the sensor 11 is inputted. The switch 13 is opened and the heater 12 is cut-off, when the temperature of the oxygen sensor 11 rises beyond a fixed value, and the switch 13 is closed. When the temperature drops under the fixed value, thus the switch operates with hysteresis, at the opening and closing time. |
