Patent ID: 6182498
Filing Date: 2001-02-06
Classification: G01N

Abstract:
An oxygen sensor disposed downstream of a catalyst, the catalyst purifying an exhaust gas from an internal combustion engine using fuel which contains hydrocarbon having a ratio of hydrogen to carbon of at lease 3:1, the oxygen sensor comprising:a sensor element having a detection electrode on a first surface of a solid electrolyte having oxygen ion conductivity and a reference electrode on a second surface thereof, anda protective cover separating an inside cavity portion and an outside region, the cavity portion for receiving said sensor element;a gas flow passage provided in said protective cover in such a manner that gas can flow both from the inside cavity portion to the outside, and from the outside to the inside cavity portion of said protective cover; andwherein the amount of the gas passing through the gas flow passage of said protective cover is restricted in such a manner that although an output voltage of the oxygen sensor varies in accordance with the concentration of at least hydrogen and carbon monoxide, the output voltage dependent on the concentration of said hydrocarbon does not exceed a reference level by which it is determined whether the air/fuel ratio is rich or lean.