| 摘要 |
PURPOSE: To improve the air-fuel ratio detecting accuracy and the durability of an air-fuel ratio detecting sensor by communicating a sensor cooling jacket, which is provided in the periphery of the air-fuel ratio detecting sensor, with an engine cooling water passage. CONSTITUTION: In the case of forming an air-fuel ratio detecting device for engine, which directly takes out the combustion gas of a combustion chamber 8 so as to detect the air-fuel ratio of the combustion gas, a sensor cooling jacket 13b is provided in the periphery of a detecting unit 14a of an air-fuel ratio detecting sensor 14, and the sensor cooling jacket 13b and an inside jacket 9a, which is positioned in the upstream side of a thermostat valve 11, are communicated with each other through a water supplying passage 16a. The sensor cooling jacket 13b and an outside jacket 9b, which is positioned in the downstream side of the thermostat valve 11, communicate with each other through a draining passage 16b. |
