Patent ID: 6821401
Filing Date: 2004-11-23
Classification: G01N

Abstract:
A sensor for measuring a concentration of a gas component in a gas mixture, comprising:a solid electrolyte conductive for ions; a diffusion barrier; and a plurality of electrodes separated by the solid electrolyte, an outer electrode of the plurality of electrodes being exposed to the gas mixture and an inner electrode of the plurality of electrodes being situated in a cavity separated from the gas mixture by the diffusion barrier, wherein: an operating mode is provided that is able to be switched over as a lean operation probe according to a limiting current principle and as a transition probe having a pumped reference, and wherein at least one of the following conditions is met: (a) in the operating mode corresponding to the lean operation probe, at the plurality of electrodes, a pump voltage, picked off from a constant voltage source and having a higher voltage potential than the inner electrode, is present at the outer electrode, and as a measure for the concentration of the gas component, a pump current caused by the pump voltage is measured after an expiration of a transient recovery time that follows a changeover switching of the operating mode, and (b) in the operating mode corresponding to the transition probe, for the purpose of pumping the reference at the plurality of electrodes, a constant current source is connected, having an anodic current flowing from the inner electrode to the outer electrode, and an electrode voltage is measured after the expiration of the transient recovery time that follows the changeover switching of the operating mode as a measure for the concentration of the gas component.