Sealing structure of gas sensor
AssigneeDenso Corporation
InventorMakoto Shirai
Life of this patent
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Abstract
An improved structure of a mechanical seal for keeping a gas chamber and a reference gas chamber airtight in a sensor body. A sensor element is disposed within an insulator. A gap between the sensor element and the insulator is sealed hermetically by a glass sealing member. The glass sealing member has a coefficient of thermal expansion whose differences between itself and the sensor element and the insulator is within a range of ±3×10−6/° C. This provides a mechanical seal required to keep the reference gas chamber and the gas chamber in the gas sensor airtight in an environment such as an automotive exhaust system subjected to a great temperature change.
Claims13
A gas sensor comprising:
- a hollow housing having a first and a second end portion;
- a sensor element having a length which includes a first and a second portion;
- a hollow insulating member disposed in said housing, retaining said sensor element therein;
- a first cover installed on the first end portion of said housing to define a first chamber in which the first portion of said sensor element is exposed to a reference gas;
- a second cover installed on the second end portion of said housing to define a second chamber in which the second portion of said sensor element is exposed to a gas to be measured;
- and
- a glass sealing member disposed between an inner wall of said hollow insulating member and an outer wall of said sensor element to establish a hermetical seal between the first and second chamber,
- wherein differences in thermal expansion between said glass sealing member and said sensor element and between said glass sealing member and said hollow insulating member are within a range of ±1×10−6/° C.
Dependencies are inferred from the claim text.