Patent ID: 6471840
Filing Date: 2002-10-29
Classification: G01N

Abstract:
A combined gas sensor comprising:a first gas chamber formed by first and second oxygen ion conductive solid electrolytes; a first gas inlet having a diffusion resistance for restricting a flow amount of gases entering the first gas chamber; a first oxygen sensing electrode active only to oxygen, which is disposed on a surface of the first oxygen ion conductive solid electrolyte substrate inside the first gas chamber; a gas sensing electrode active to at least target gases and oxygen, which is disposed on the same surface of the first electrolyte substrate as the first oxygen sensing electrode inside the first gas chamber; a reference electrode active to oxygen, which is disposed on the first solid electrolyte substrate such that it is brought into contact with an atmospheric air separated from the first gas chamber; an oxygen pump cell for controlling oxygen concentration in the first gas chamber, of which electrodes are made of materials active only to oxygen and disposed on the second solid electrolyte substrate facing to the first solid electrolyte substrate; a gas reforming pump cell for electrochemically converting or decomposing the gases, of which a gas reforming electrode is active to oxygen and the target gases, and disposed on the second solid electrolyte substrate inside the first gas chamber so as to face the gas sensing electrode, and a gas reforming counter electrode disposed on the second solid electrolyte substrate outside the gas chamber such that it is brought into contact with the atmospheric air; and a second oxygen sensing electrode active only to oxygen, which is disposed on the first solid electrolyte substrate such that it is directly exposed to a detection gas atmosphere.