Denso Corporation

Tooru Katafuchi

Namitsugu Fujii

Yasumichi Hotta

Hiromi Sano

Kiyomi Kobayashi

Hiroshi Sugino

A method of manufacturing a gas sensor element which includes a solid electrolyte body, a target gas electrode a reference gas electrode provided on a surface of the solid electrolyte body so as to be exposed to a reference gas and the manufacturing method includes exposing the gas sensor element to a gas atmosphere containing at least one of a hydrocarbon gas, a CO gas, and a H gas and applying an ac voltage to said target gas electrode and the reference gas electrode. Each of the target gas electrode and the reference gas electrode is made up of a plurality of crystal grains defined by grain boundaries having a total length of 1000 &mgr;m or more in a surface area of 100 &mgr;m .

Method of producing a gas sensor element

An oxygen sensor element is provided which may be used in an oxygen sensor designed to measure the concentration of oxygen contained in exhaust gasses of an automotive internal combustion engine. The gas sensor element includes a solid electrolyte body, a target gas electrode, a reference gas electrode, and a catalytic layer formed over the target gas electrode. The catalytic layer is made of heat resisting ceramic grains which hold thereon catalytic metal grains whose average grain size is 0.3 to 2.0 &mgr;m, a weight of catalytic metal grains per unit area of the catalytic layer, as defined by projecting the target gas electrode on a plane, is 10 to 200 &mgr;g/cm . This facilitates the reaction of exhaust gasses such as H , NOx, and HC with O over the target gas electrode, thus resulting in improved accuracy of a sensor output over a wide temperature range.

Oxygen sensor element

A gas sensor element is provided which is used in a gas sensor such as an oxygen sensor. The gas sensor element includes a solid electrolyte body, a target gas electrode provided on a surface of the solid electrolyte body so as to be exposed to a gas to be measured, and a reference gas electrode provided on a surface of the solid electrolyte body so as to be exposed to a reference gas. Each of the target gas electrode and the reference gas electrode is made up of a plurality of crystal grains defined by grain boundaries. The total length of the grain boundaries in each of the target gas electrode and the reference gas electrode is 1000 &mgr;m or more in a surface area of 1000 &mgr;m . This ensures a sufficient degree of diffusion of the gasses in the target and reference gas electrodes, thereby providing a rapid response rate to the gas sensor element.

Gas sensor element

A solid electrolytic body has an inside space serving as a reference gas chamber. A sensing electrode and a reference electrode are formed on the surface of the solid electrolytic body. A heater is disposed in the reference gas chamber. A contact portion comprises a region where the heater is brought into contact with the inner surface of the solid electrolytic body and an opposing region on the outer surface of the solid electrolytic body. The sensing electrode includes at least part of the contact portion. A gas receiving surface region, exposed to the measuring gas, extends from an element tip to a position spaced by a distance L away from the element tip. At least part of the contact portion is located in a region extending from the element tip to a position spaced by a distance 0.4L away from the element tip. The sensing electrode is entirely located in a region extending from the element tip to a position spaced by a distance 0.8L away from the element tip.

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Kariya, Japan

Tooru Katafuchi