Patent ID: 7559229

Claim:
A gas sensor for detecting a concentration of a specified gas component in measuring gases, comprising: a concentration sensing element having a base end portion and a leading end portion for detecting the concentration of the specified gas component in the measuring gases; a housing for insertion of the concentration sensing element to fixedly support the concentration sensing element to allow the leading end portion of the concentration sensing element in a flow passage through which a stream of measuring gases flows; and a bottomed cylindrical cover body structure, fixedly supported with the housing and having a cylindrical multiple-layer structure, which includes an inner shell and an outer shell different in diameter from each other and disposed in a concentric relation to each other so as to surround the leading end portion of the concentration sensing element in an area exposed to the stream of measuring gases; wherein an annular sideways clearance is defined between an outer periphery of the inner shell and an inner periphery of the outer shell; wherein the inner shell has a base end portion and a leading end portion, the base end portion of the inner shell having inner-shell sidewall openings formed in components directed upward from an outside area of the inner shell to an inside area thereof, the inner shell having an inner-shell bottom wall whose central area is formed with an inner-shell bottom wall opening; wherein the outer shell has a base end portion and a leading end portion, the base end portion of the outer shell having a plurality of outer-shell sidewall openings for admitting the stream of measuring gases to the annular sideways clearance; wherein the leading end portion of the outer shell has an outer-shell bottom wall spaced from the inner-shell bottom wall to define a bottom clearance therebetween; wherein a plurality of outer-shell bottom wall openings are formed on the outer-shell bottom wall in an outer circumferential area radially outside the inner-shell bottom wall opening; wherein the inner shell has a plurality of inner-shell sidewall openings axially offset from the outer-shell sidewall openings of the outer shell to positions closer to the leading end portion of the inner shell; and wherein the leading end portion of the outer shell includes a tapered portion that decreases in diameter toward the outer-shell bottom wall.