Nippondenso Co., Ltd.

Denso Corporation

Seiki Nakagawa

Yukihisa Takeuchi

Keiji Kanao

Hitoshi Yoshida

Yoshitaka Sato

Hiroshi Kondo

Hideo Asakura

A spark plug having a tip composed of an iridium alloy essentially consisting of iridium is resistance welded through a relieving layer to a front end of a center electrode having an iron-based alloy and a facing portion of a ground electrode and wherein the material of the relieving layer has a coefficient of linear expansion between the iridium alloy and the iron-based alloy and has a Young's modulus of elasticity smaller than that of the two alloys.

Spark plug having iridum alloy tip, iron-based alloy tip bonding portion and stress relieving layer therebetween

An ignition distributor wherein at least either one of the discharge element of a stationary electrode and the discharge element of a rotary electrode are composed of a sintered body comprising at least a ferrite and silicon oxide and have a surface precipitate layer having a thickness of from 1 to 7 .mu.m and a silicon oxide content larger than that of a core portion of the sintered body and the discharge element has an electric resistivity of from 10.sup.4 to 10.sup.6 .OMEGA. in a portion from a site at which said voltage is applied to the discharge element to a site at which an electric discharge occurs.

Ignition distributor

A sintered ceramic structure for cleaning noxious substances contained in the exhaust gases emitted by an internal combustion engine is disclosed. The stucture comprises: an exhaust-gas cleaning portion including a multiplicity of pores through which the exhaust gas is discharged and an exhaust-gas inlet portion and an exhaust-gas outlet portion; an external wall portion being integrally disposed around the outer periphery of the exhaust-gas cleaning portion except for both the exhaust-gas inlet portion and the exhaust-gas outlet portion of the exhaust-gas cleaning portion; the exhaust-gas cleaning portion and the external wall portion being constituted by ceramics; and the ceramics of the external wall portion being composed of a sintered ceramic material having a sintering-shrinkage ratio smaller than that of the ceramics of the sintered ceramic material of the noxious gas cleaning portion, whereby upon sintering a residual compressive stress is imparted to the external wall portion due to the difference between the sintered-shrinkage ratios.

Sintered ceramic filter structure having body compressively stressed by

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Takahama, Japan

Seiki Nakagawa