| 摘要 |
A component of the reference gas, which can be oxidized, is selectively restrained (14) in its approach to the reference electrode (15). Restraint implies reduction, delay or prevention of such approach. Alternatively or in addition, oxidation of such a component at the reference electrode is at least partially prevented. Preferred Features: Hydrocarbon (HC) is held back as described, and its oxidation is prevented or limited at the electrode. A reference gas volume (13) (for oxygen) surrounds the electrode, connected to the reference gas channel (10). The electrode is heated or is in a hot part of the sensor. A diffusion barrier (14) has greater permeability for oxygen than the reductant component of the exhaust gases. The diffusion barrier has greater permeability or diffusion rate for oxygen molecules than for the hydrocarbon, which has greater molecular weight than oxygen. It is integrated with or connected to the reference gas channel and comprises a porous filling. Diffusion barrier and porous filling have an open porosity of 10 vol% to 60 vol% and a pore size of 1-20 mu m, especially 5-10 mu m. The diffusion barrier is spaced by the reference gas channel from the reference electrode and/or is located in a cold part (16) of the sensor. Further variants of the design based on the foregoing principles, are described.
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