Patent ID: 7497109

Claim:
A gas sensor comprising: a hollow cylindrical housing; a sensor element including a sensing portion and a base portion, said sensing portion working to produce a signal as a function of concentration of a target component of gases; a first porcelain insulator having a top end surface and a base end surface opposed to the top end surface, said first porcelain insulator being installed in said housing and through and having said sensor element pass therethrough to expose the sensing portion to the gases outside the top end surface of said housing; a second porcelain insulator having a top end surface and a base end surface opposed to the top end surface, said second porcelain insulator being aligned with said first porcelain insulator in abutment of the top end surface thereof with the base end surface of said first porcelain insulator; and a ground flat area formed on at least one of the base end surface of said first porcelain insulator and the top end surface of said second porcelain insulator to define an area of contact between the base end surface of said first porcelain insulator and the top end surface of said second porcelain insulator, the ground flat area being formed using one of a lapping machine and a grinding machine, whereby there is an increase in an area of contact between the base end surface of said first porcelain insulator and the top end surface of the second porcelain insulator at said abutment, thereby minimizing a concentration of stress on said area of contact.