Planar polarographic sensor for determining the lambda value of gas mixtures

A sensor arrangement which is a multiple printed panel, comprising:

• a plurality of planar polarographic sensors for determining the lambda value of gas mixtures for use with exhaust gases in internal combustion engines disposed side by side, each sensor of the plurality of planar polarographic sensors being comprised of:
• a planar ceramic carrier sheet having an outer pumping electrode and an inner pumping electrode respectively arranged on opposite planar sides thereof;
• and
• a diffusion barrier,
• wherein the outer and inner pumping electrodes, and the diffusion barrier are arranged on the planar ceramic carrier sheet so that measuring gas is fed via the diffusion barrier to the inner pumping electrode,
• wherein the sensor has front and side edge faces, and the diffusion barrier is configured as a diffusion layer which at least partially covers the inner pumping electrode and which is exposed to the measuring gas at least at one edge face of the sensor,
• wherein a diffusion-free planar region of the sensor is provided with an equalizing layer having the same thickness as the diffusion layer, and the equalizing layer is disposed in the same plane with and adjacent to the diffusion layer, and
• wherein the equalizing layer extends toward the front edge face of the sensor along two side edge faces of the sensor between the diffusion layer and the two side edge faces of the sensor up to the front edge face of the sensor, and the diffusion layer extends to the front edge face, such that the diffusion layer is exposed to the measuring gas along a part of the front edge face bounded by the equalizing layer;
• and
• wherein the diffusion layers of respective sensors collectively comprise a single common diffusion layer which projects over a front edge of the panel.

A method of producing a sensor arrangement which is a multiple printed panel comprised of:

• a plurality of planar polarographic sensors for determining the lambda value of gas mixtures for use with exhaust gases in internal combustion engines disposed side by side, each sensor of the plurality of planar polarographic sensors, comprising:
• a planar ceramic carrier sheet having an outer pumping electrode and an inner pumping electrode respectively arranged on opposite planar sides thereof;
• and
• a diffusion barrier,
• wherein the outer and inner pumping electrodes, and the diffusion barrier are arranged on the planar ceramic carrier sheet so that measuring gas is fed via the diffusion barrier to the inner pumping electrode,
• wherein the sensor has front and side edge faces, and the diffusion barrier is configured as a diffusion layer which at least partially covers the inner pumping electrode and which is exposed to the measuring gas at least at one edge face of the sensor, and
• wherein a diffusion-free planar region of the sensor is provided with an equalizing layer having the same thickness as the diffusion layer, and the equalizing layer is disposed in the same plane with and adjacent to the diffusion layer;
• and
• wherein the diffusion layers of respective sensors collectively comprise a single common diffusion layer which extends over the entire width of the multiple printed panel and projects beyond the front edge faces of the plurality of sensors, the method comprising:
• providing a plurality of individual ceramic carriers;
• providing outer and inner pumping electrodes arranged on the respective ceramic carriers;
• forming a multiple printed panel by joining on a substrate the plurality of individual ceramic carriers arranged side by side with front edges thereof parallel and in line so that the carriers are adjacent to one another;
• providing a diffusion layer which projects beyond at least the front edge of the individual ceramic carriers;
• and
• providing the diffusion-free planar region of the multiple printed panel with an equalizing layer of approximately the thickness of the diffusion layer.