Measuring and testing – Gas analysis – Gas of combustion
Patent
1997-08-29
1999-09-21
Dombroske, George
Measuring and testing
Gas analysis
Gas of combustion
73 3105, G01M 1500
Patent
active
059556560
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention relates to a measuring sensor, in particular for determining the oxygen content of exhaust gases in internal combustion engines, having a sensor element fixed in a housing, a sealing flange mounted on the housing and resting on a sealing seat in an installed position, and a fastening element which is guided over and onto the housing and can be screwed into a threaded opening, with the fastening element pressing the sealing flange against the sealing seat.
From European Patent Application EP A1 624 791 (U.S. Pat. No. 5,329,806), a gas sensor is known in which a sensor element is fixed in gastight fashion in a tubular metal housing. On its lower part the tubular housing has a radially outward-pointing lip that forms a sealing flange. The gas sensor is placed in an opening of an exhaust system, with the lip seated on a sealing seat embodied in the opening. A hollow screw is guided over onto the housing and screwed into a thread disposed in the opening and thus connects the lip to the exhaust system in a gastight fashion. A problematic aspect of this embodiment, however, is that the pressing or upsetting of the relatively thin-walled material of the housing can cause microscopic cracks, which cause the housing to leak.
SUMMARY AND ADVANTAGES OF THE INVENTION
The above drawback of the known arrangements generally are overcome according to the present invention by a measuring sensor, in particular for determining the oxygen content in exhaust gases of internal combustion engines, having a sensor element fixed in a housing, a sealing flange mounted on the housing and resting on a sealing seat in an installed position, and a fastening element which is guided over and onto the housing and can be screwed into a threaded opening, with the fastening element pressing the sealing flange against the sealing seat, and wherein the housing has a housing part on the side toward the gas to be measured and a housing part on the side toward the connection, and that the sealing flange is disposed on the housing part on the side toward the connection.
The invention as defined above has the advantage over the prior art that the sealing flange is absolutely gastight. A two-piece housing with a sealing flange disposed on the housing part on the side toward the connection is not only simple to manufacture but can also be manipulated easily during assembly.
By means of other disclosed provisions advantageous further features of and improvements to the measuring sensors according to the invention as disclosed above are possible. Producing the sealing flange by the production process of rotary swaging has proved to be especially appropriate. It is also expedient to attach a connection piece to the exhaust pipe; this piece then forms a sealing seat for the sealing flange on its end face. By mounting a union nut on the sealing flange and by its cooperation with a thread provided on the connection piece, the sealing flange is joined in gastight fashion to the connection piece.
BRIEF DESCRIPTION OF THE DRAWING
An exemplary embodiment of the invention is shown in the drawing and described in further detail in the ensuing description. The sole drawing Figure is a longitudinal section through a gas sensor inserted into an exhaust pipe.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT
A gas sensor 10, such as an electrochemical oxygen sensor, is inserted into an exhaust pipe 11 and has a metal housing part 12 on the side toward the gas to be measured and a metal housing part 13 on the side toward the connection, which together form a housing 14. A planar sensor element 16 having a portion 17 on the side toward the gas to be measured and a portion 18 on the side toward the connection is fixed in the housing 14 in gastight fashion.
The housing part 12 on the side toward the gas to be measured is a tube element, for instance open on both ends, with a cylindrical wall 21 on the inside. On its end on the side toward the connection, the housing part 12 on the side toward the gas to be measured has a portion 22, for i
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Eisenschmid Heinz
Graser Theodor
Hoetzel Gerhard
Wehrmann Johann
Dombroske George
Kunitz Norman N.
McCall Eric S.
Robert & Bosch GmbH
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