Chemistry: electrical and wave energy – Apparatus – Electrolytic
Patent
1997-09-30
2000-07-04
Warden, Sr., Robert J.
Chemistry: electrical and wave energy
Apparatus
Electrolytic
204424, 204428, 277943, G01N 27416, G01N 27407
Patent
active
060833718
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a gas sensor, particularly for exhaust gases of internal combustion engines, having a planar sensor element that is fixed in a longitudinal bore of a housing of a sealing arrangement that has two molded parts that can be pressed together by means of a spring element, and has a sealing material that is disposed between the molded parts and surrounds the sensor element.
2. Description of the Related Art
Gas sensors of the generic type are known. For example, DE 32 06 903 A1 discloses a gas sensor in which a planar sensor element is fixed in a longitudinal bore of a housing with two superposed, electrically-insulating molded parts. Between the molded parts, the sensor element is surrounded by an electrically-insulating powder that is compressed during assembly and is maintained in its compressed state by a spring element. Inside the housing, the powder forms a seal for the sensor element that separates a measured-gas chamber and a reference-gas chamber for the sensor element. It is known to use steatite as the sealing powder. A disadvantage of this is that, on the one hand, the steatite powder has a residual porosity that can cause leakages between the measured-gas chamber and the reference-gas chamber. Another disadvantage is that the steatite powder has a lower thermal expansion coefficient than the surrounding housing, so leakages can also occur due to heating of the gas sensor over the course of operation.
SUMMARY OF THE INVENTION
In contrast, in the gas sensor of the invention at least one of the molded parts forms a receptacle for the sealing material, and the spring element causes the sealing material to be compressed and/or plastically deformed into this receptacle by the further molded part, and the sealing material is maintained in the compressed and/or plastically-deformed position. This has the advantage of reliably maintaining a seal between the measured-gas chamber and the reference-gas chamber, even with extreme mechanical and/or thermal stress of the gas sensor. Because at least one of the molded parts of the sealing arrangement forms a receptacle for the sealing material, and a spring element causes the sealing material to be compressed and/or plastically deformed in this receptacle by the further molded part, and the sealing material is maintained in the compressed and/or plastically-deformed position, it is advantageously possible to exert a strong pressing force onto the sealing material such that the material is compressed enough to reliably preclude a connection between the measured-gas chamber and the reference-gas chamber, both by the sealing material itself and at the contact surfaces between the sealing material and the sensor element.
It is particularly advantageous if the molded parts that receive the sealing material have a lower thermal expansion coefficient than the sealing material. This advantageously permits the sealing material to expand more than the molded parts during operation-stipulated heating of the sensor element, and thus of the sealing material and the molded parts, so the sealing effect is at least retained, if not increased.
Further, advantageous embodiments of the invention ensue from its other features, which are disclosed in the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in detail below by way of embodiments illustrated in the attached drawings. Shown are in:
FIG. 1 a longitudinal section through a sealing arrangement of a gas sensor according to a first embodiment variation,
FIG. 2 a longitudinal section through a sealing arrangement of a gas sensor according to a second embodiment variation, and
FIG. 3 a partial longitudinal section through a sealing arrangement of a gas sensor according to a third embodiment variation.
DESCRIPTION OF THE EMBODIMENTS
FIGS. 1 through 3 show sectional views of a gas sensor 10 with its components that are essential to the present invention. For better clarification, identical parts shown in the different
REFERENCES:
patent: 4310401 (1982-01-01), Stahl
patent: 4818363 (1989-04-01), Bayha et al.
patent: 5302274 (1994-04-01), Tomantschger et al.
patent: 5467636 (1995-11-01), Thompson et al.
patent: 5846391 (1998-12-01), Friese et al.
Jauernig Udo
Weyl Helmut
McNeil Jennifer
Robert & Bosch GmbH
Spencer George H.
Warden, Sr. Robert J.
Wells Ashley J.
LandOfFree
Sealing device for gas sensor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sealing device for gas sensor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sealing device for gas sensor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1482653