Patent ID: 7490404

Claim:
A gas sensor manufacturing method comprising the steps of: preparing an assembly which has a length and includes (a) a housing which has a length made up of a first end portion, a second end portion, and a flange between the first and second end portions, (b) a cover which is made up of a small-diameter portion, a large-diameter portion, and a shoulder formed between the small-diameter portion and the large-diameter portion, and (c) an insulation porcelain disposed in the large-diameter portion of the cover in contact with the shoulder through an elastic member, (d) a cup-shaped sensor element disposed in the housing; preparing a stationary plate, the stationary plate retains the second end portion of the housing firmly; fitting a press plate on the small-diameter portion of the cover; moving the press plate toward the stationary plate, the press plate moving into abutment with the shoulder of the cover at a first speed and, after the press plate hits the shoulder, pressing the plate at a second speed lower than said first speed until pressure exerted on the shoulder reaches a given value to fit an end of the large-diameter portion of the cover on the first end portion of the housing to form an overlap and exert elastic pressure on the insulation porcelain through the elastic member; and welding the large-diameter portion of the cover to the first end portion of the housing over the overlap while pressing the cover against the housing.