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US 5,492,612 AGranted
Lean shift correction of potentiometric oxygen sensors
AssigneeGeneral Motors Corporation
InventorsFrederick L. Kennard, III, Carlos A. Valdes
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Abstract
The invention includes the use of a pre-equilibration zone on an exhaust gas sensor to provide catalytic site to catalyze non-reacted components of the exhaust gas prior to the gas sample reaching the sensor's outer electrode. The pre-equilibration zone preferably includes a precious metal on the surface of a porous carrier. The invention also includes a method of making an exhaust sensor including a pre-equilibration zone, and a method of sampling an exhaust gas by passing the same through a pre-equilibration zone.
Claims6
An exhaust sensor comprising:
- inner and outer electrodes, an electrolyte body between the electrodes, and a first porous protective coating on the outer electrode, said first porous protective coat having a thickness ranging from about 100 to about 500 microns;
- a catalytic pre-equilibration layer overlying the first porous protective coat so that the first porous protective coat separates the outer electrode from the catalytic pre-equilibration layer, said catalytic pre-equilibration layer consisting essentially of at least one metal selected from the group consisting of platinum, palladium, rhodium, transition metals and mixtures thereof, and said catalytic pre-equilibration layer having a thickness ranging from about 100 Angstroms to 100 microns.
Dependencies are inferred from the claim text.