| 摘要 |
PROBLEM TO BE SOLVED: To provide a theoretical air fuel ratio sensor element in which the time required until an electrode of a sensor portion reaches a predetermined temperature can be shortened to enhance activation, whereby the sensor can be started more rapidly. SOLUTION: The theoretical air fuel ratio sensor element is equipped with a sensor portion 11 having an elongated solid-state electrolytic substrate 3 and a pair of electrodes 4, 5 formed on both the confronting principal faces in the neighborhood of the tip of the solid-state electrolytic substrate 3, and a heating portion 12 having a heating member 8 which is contained in an insulating layer 7 and heats the sensor portion 11. The temperature rise-up velocity of the tip portion A of the electrode 5 of the sensor portion 11 just after a voltage of 12 V is applied to the heating element 8 is highest, the time t1 required until the surface temperature of the tip portion A of the electrode 5 reaches 650 deg.C is equal to 20 seconds or less, a time t2 required until the surface temperature of the rear end portion B of the electrode 5 reaches 650 deg.C is equal to 35 seconds or less, and the difference t3 between the required time (=t2-t1) until the surface temperature at the electrode tip portion A and the electrode rear end portion B reaches 650 deg.C is equal to 5 to 17 seconds. |
