GAS SENSOR ELEMENT, GAS SENSOR, AND METHOD OF MANUFACTURING GAS SENSOR ELEMENT

摘要

A gas sensor element in an air/fuel ratio sensor includes an element body and a protection layer having two layers (a first layer and a second layer). The gas sensor element has at least one separation portion in the form of a space between the first layer and the second layer. The gas sensor element can temporarily accumulate, in the at least one separation portion, water which adheres to the surface of the protection layer and penetrates into the protection layer. Thus, as compared with a protection layer which is identical in thickness to the protection layer, but does not have separation portions, water adhering to the protection layer is less likely to reach the element body. Therefore, there can be restrained breakage of an end of the element body which could otherwise result from thermal shock stemming from adhesion of water.

主权项

1. A gas sensor element comprising:
an element body having a substantially rectangular-parallelepiped shape extending in a longitudinal direction, a forward end surface, and four side surfaces, and including a detecting section for detecting a particular gas; and a protection layer located on the forward end surface and the four side surfaces of the element body in such a manner as to cover at least the detecting section, the protection layer having a largest thickness at a place on the four side surfaces of the element body and formed in a porous manner and at least a first layer formed on the element body and a second layer formed externally of and in contact with the first layer, the first layer and the second layer differing in material or property and defining at least one separation portion in the form of a space between the first layer and the second layer and formed only in a forward region located forward of the place of the largest thickness of the protection layer; wherein the first layer and the second layer of the protection layer are laminated together without the separation portion intervening therebetween on at least a portion of the forward end surface and on at least a portion of the four side surfaces in the forward region.