| 摘要 |
PURPOSE:To reduce detection errors on contact with the atmosphere of lambda(air/fuel ratio)<1 and detection errors due to a combustible gas yet to react, by setting a gas detection piece side sintered body made of a perovskite compound as sensor material at 10% or more in the pore opening ratio while a temperature compensation piece side sintered body made of the same material at 0-5% therein. CONSTITUTION:A 6-hole tube substrate 2 made of alumina fitted with a heater-built-in ceramic tube 4 at the tip thereof. A gas detection piece 8 and a temperature compensation piece 10 are provided in a recess between the substrate 2 and the ceramic tube 4 through a threshold part 12. The gas detection piece 8 is so constructed that a pair of precious metal electrodes 16 and 18 are buried into a porous sintered body 14 made of CaTiO3-delta or SrTiO3-delta and the assembly there of is covered entirely with a porous ceramics film 20 about 100mum. The pore opening ratio is set at 10-45%. Regarding the temperature compensation piece 10, the pore opening ratio is set at 5% or less. Changes in the resistance values of the gas detection piece 8 and the temperature compensation piece 10 are detected as changes in the voltages to be applied to load resistances R1 and R2. On the other hand, to keep the temperature of an emission gas sensor constant, the voltage applied to a film heater 6 is changed in a proportional control manner depending on the difference between the target and real temperature. |
