Patent ID: 6451187
Filing Date: 2002-09-17
Classification: G01N

Abstract:
An air/fuel ratio sensor, comprising:an air/fuel ratio detector comprised of a laminated body formed by stacking an oxygen reference electrode, a dense solid electrolyte, a negative electrode, a porous solid electrolyte, a positive electrode, and a porous protection film on one another; and a ceramic substrate having a heater built therein, wherein said air/fuel ratio detector and said ceramic substrate are joined to each other in layered form, wherein part of said oxygen reference electrode is shaped in a pattern having a form extremely thinner than the remaining portion thereof, and said pattern of thinner form is directly in contact with an exhaust gas atmosphere through layer-to-layer spacing of said laminated body which constitutes said air/fuel ratio detector, and wherein said oxygen reference electrode, said negative electrode and said positive electrode in said laminated body constituting said air/fuel ratio detector are provided so as to be shorter in length than said dense solid electrolyte, said porous solid electrolyte and said protection film and biased to a longitudinally-extending one end of said laminated body, whereby said air/fuel ratio detector is positioned at a longitudinally-extending one end of a laminated structure, and a pattern for said heater is shaped in the form of such a pattern that said air/fuel ratio detector side is dense and gradually becomes less dense towards an end on the opposite side of said air/fuel ratio detector as viewed in the longitudinal direction of said laminated body.