Patent ID: 8656756
Filing Date: 2014-02-25
Classification: G01N

Abstract:
1. A gas sensor comprising: a cylindrical metal shell extending along an axial direction from a leading end thereof to a base end thereof; a plate-shaped detection element main body extending along the axial direction from a leading end thereof to a base end thereof and held radially inside the metal shell, the detection element main body comprising an element protruding portion protruding from the leading end of the metal shell in the axial direction; a porous protection layer coated on a leading end portion of the detection element main body; and a protector attached to the metal shell and comprising a side wall surrounding the element protruding portion in a radial direction perpendicular to the axial direction without intervention of other member, the side wall having introduction holes formed therein which allow gas to be introduced into an inner space which includes the element protruding portion defined by the sidewall, wherein the porous protection layer comprises: a first portion; and a second portion provided on a base end side with respect to the first portion, the second portion having a progressively reduced thickness in a direction toward the base end of the detection element main body, wherein the second portion of the porous protection layer is disposed closer to the base end of the detection element than the introduction holes in the axial direction; wherein the introduction holes are disposed at a same position as the element protruding portion in the axial direction; wherein the introduction holes are disposed at a same position as the first portion of the protection layer in the axial direction so as to quicken response time of the gas sensor; wherein the entire part of the second portion of the protection layer is disposed closer to the base end of the detection element than all of the introduction holes in the axial direction so as to suppress cracking of the protection layer due to water droplets passing through the introduction holes of the sidewall; and wherein the second portion is disposed within the metal shell.