Measuring and testing – Gas analysis – With compensation detail
Patent
1999-02-22
2000-12-26
Larkin, Daniel S.
Measuring and testing
Gas analysis
With compensation detail
73 2331, 73 3105, 204424, 204426, G01N 27407
Patent
active
061641200
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND INFORMATION
The present invention relates to a sensor and a method of manufacturing a sensor. in which German published patent application No. 19523903 describes a known sensor a planar sensor element is secured, in a gas-tight manner, in a bushing of an exhaust gas-side ceramic molded component, using metal solder. The exhaust gas-side ceramic molded component has a depression on its end facing away from the exhaust gas, in which the metal solder is introduced.
SUMMARY OF THE INVENTION
The sensor according to the present invention has the advantage that a mechanically more stable and more gas-tight bond between the planar sensor element and the ceramic molded component can be achieved. The ductile metal-based sealing element ensures sufficient protection against crack formation in the area of the join. Hot forming of the metal-based sealing element allows a combination joining method to be used, in which the process operations of hot forming, shrink-fitting, and optionally diffusion welding are combined. The method according to the present invention allows the sensor element seal to be manufactured in a cost-effective manner. In the joining process, the sealing element is hot-formed between the two ceramic molded components so that the planar sensor element is enclosed and the sealing element is sealingly pressed against the surface of the sensor element.
According to the present invention it is particularly advantageous if the formable sealing element and the geometry of the hollow space or gap between the two ceramic molded components are designed so that the material of the sealing element can expand on the sensor element within certain limits, even axially, during hot forming. The joining process is advantageously performed above the maximum temperatures of use occurring later, so that the sealing element is shrink-fitted onto the sensor element due to its; higher thermal expansion coefficient and possibly additional diffusion welding can take place between the sealing element, the sensor element and the ceramic molded component.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a cross-section through the sensor according to the present invention.
FIG. 2 shows a first embodiment of a sensor element seal with a device for manufacturing the seal according to the present invention.
FIG. 3 shows another embodiment of the sensor element seal of FIG. 2.
FIG. 4 shows yet another embodiment of the sensor element seal of FIG. 2.
FIG. 5 shows still another embodiment of the sensor element seal of FIG. 2.
FIG. 6 shows still another embodiment of the sensor element seal of FIG. 2.
FIG. 7 shows yet another embodiment of the sensor element seal of FIG. 2.
DETAILED DESCRIPTION
The sensor illustrated in FIG. 1 is an electrochemical sensor for determining the oxygen level in exhaust gases of internal combustion engines. The sensor has a metallic enclosure 10, in which a plate-shaped sensor element 12 is arranged with an end section 13 on the measured gas side, and an end section 14 on the connection side. Enclosure 10 is designed to be installed in an exhaust pipe (not illustrated) using a thread as fastening means. Furthermore, a longitudinal bore 16, with a first shoulder-shaped ring surface 17, for example, and a second shoulder-shaped ring surface 18, is arranged in enclosure 10.
A measured gas-side ceramic molded component 20 is arranged in longitudinal bore 16 with a measured gas-side bushing 24, a measured gas-side face 21, and a connection-side face 22. Measured gas-side face 21 has a conical sealing seat 23, which sits on metallic seal ring 25 in contact with second shoulder-shaped ring surface 18. A connection-side ceramic molded component 27 includes a connection-side bushing 30, with a measured gas-side face 28 and a connection-side face 29 is arranged over measured gas-side ceramic molded component 20.
A mechanically pre-stressed disk spring 31, exerting pressure via a tube-shaped holding cap 32 on connection-side ceramic molded component 27 projecting from enclosure 10, is on connectio
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Friese Karl-Hermann
Geier Heinz
Weyl Helmut
Wiedenmann Hans-Martin
Larkin Daniel S.
Robert & Bosch GmbH
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