Catalyst – solid sorbent – or support therefor: product or process – Miscellaneous
Reexamination Certificate
2000-03-30
2001-11-13
Griffin, Steven P. (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Miscellaneous
C502S527190, C428S116000
Reexamination Certificate
active
06316384
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a honeycomb body configuration, in particular for catalyst-carrier bodies for purifying exhaust gases of motor vehicles.
German Utility Model G 74 01 002, for example, discloses a honeycomb body configuration having a housing, a honeycomb body disposed in the housing and having varying radial strength along its periphery, and a compensation layer disposed between the housing and the honeycomb body.
Honeycomb bodies of that kind have a plurality of channels separated from one another by dividing walls. The channels have square, rectangular or other polygonal cross-sections. U.S. Pat. No. 3,853,485 describes various cross-sectional shapes.
Due to the geometrical configuration of the channels and the configuration of the channels inside a cross-sectional surface area of the honeycomb body, a honeycomb body of that kind has varying strengths distributed peripherally in the radial direction. Those varying strengths of the honeycomb body also affect the breaking behavior and elastic behavior of the honeycomb body. International Publication No. WO 94/15712 discloses a honeycomb body having increased elasticity, wherein, in particular, the elasticity properties do not differ in different directions. According to the proposal in International Publication No. WO 94/15712, the honeycomb body has dividing walls at least in one outer region. The dividing walls are disposed and shaped in such a way that in cross-section through the honeycomb body structures which are rigid in the radial direction and/or rigid supporting structures extending in the peripheral direction are not formed by them.
A honeycomb body of that kind which is produced from a ceramic and/or metal material is advantageous in that it is not easily destroyed by forces acting through a housing in the radial direction upon the honeycomb body. That is because the honeycomb body has uniform strength radially over its periphery.
The theoretical problem of a honeycomb body being destroyed by forces which the housing exerts uniformly in the radial direction upon the honeycomb body is solved by International Publication No. WO 94/15712.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a honeycomb body configuration with support sections, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and in which damage, even to a catalyst carrier body with different properties of radial strength over its periphery, by forces directed radially by the housing, can be avoided.
With the foregoing and other objects in view there is provided, in accordance with the invention, a honeycomb body configuration, comprising a metal housing; a honeycomb body disposed in the metal housing, the honeycomb body having a radial direction, a periphery defining a peripheral direction, varying radial strength along the periphery defining regions of greater radial strength, and dividing walls defining and separating a multiplicity of channels from one another; and a compensation layer disposed at least in partial regions of the periphery between the housing and the honeycomb body, the compensation layer having at least two support sections in the peripheral direction of the honeycomb body and having remaining peripheral regions outside the at least two support sections, the at least two support sections disposed in the regions of greater radial strength, the at least two support sections exerting greater forces in radial direction upon the honeycomb body than in the remaining peripheral regions, and the at least two support sections formed at least partly by at least one insert formed of a metal material.
The invention is based on the concept that the radial properties of strength of a honeycomb body which vary along the periphery can be utilized to promote a stable hold in the housing if a compensation layer of appropriate construction is disposed between the honeycomb body and a housing. The compensation layer which is disposed between the housing and the honeycomb body has at least two support sections in the peripheral direction of the honeycomb body. These support sections exert greater forces in the radial direction upon the honeycomb body than onto the honeycomb body outside the support sections in the remainder of the peripheral regions. The support sections of the compensation layer are formed therein in regions where the honeycomb body has greater radial strength. The forces which are exerted by the housing onto the honeycomb body are received essentially in the regions of the support sections and are introduced into the relatively rigid structure of the honeycomb body. In the remainder of the peripheral regions which are disposed between each two adjacent support sections of the compensation layer, only small forces, or no forces at all, are introduced into the honeycomb body. By virtue of the compensation layer inside the housing, the honeycomb body is supported virtually in at least two places, or in two regions, as seen in section.
This embodiment of the honeycomb body configuration according to the invention ensures that the honeycomb body does not become destroyed when the honeycomb body configuration is being produced, i.e. during installation inside a housing. Another advantage of this construction is that during operation of the honeycomb body configuration the forces occurring as a result of heat expansion are received principally by the support sections, that is to say in the most stable directions of the honeycomb body.
The honeycomb body can be a metal and/or ceramic body. The channel cross-sections can have a relatively simple geometry, resulting in the formation of direction-dependent radial strengths of the honeycomb body. Typically, the invention is especially suitable for particularly thin-walled, extruded ceramic honeycomb bodies, in particular with channels of square cross-section, wherein support in four support sections is preferred, each of which exerts forces upon the honeycomb body in the direction of the channel walls.
The varying strength of the honeycomb body can be compensated for by suitably selecting the properties of the compensation layer itself. A preferred embodiment of the compensation layer is such that the support sections have a greater weight per unit of area than the other sections of the compensation layer. In particular, the support sections have a greater density than the other sections. By virtue of this embodiment of the compensation layer, a different behavior with respect to deformation is obtained between the support sections and the remainder of the peripheral regions. Greater strength of the support sections can also be obtained if the support sections are formed at least partly by at least one insert.
The insert can have a sandwich-like structure, for example, which means that the forces directed radially towards the honeycomb body by the housing are received by the insert.
Alternatively, or additionally, the insert can be formed of a material which has greater strength than a material of the other sections of the compensation layer. The use of a metal material therein is preferred.
In accordance with another feature of the invention, the insert can also serve as a contact location for an electrical terminal if the honeycomb body is intended to be an electrically heatable honeycomb body.
Preferably, the compensation layer which is disposed between the honeycomb body and the housing is at least partly in the form of a matting, which also results in the honeycomb body being thermally insulated from the housing. The compensation layer preferably contains at least one matting composed of ceramic fibers, wherein so-called “swelling mattings” are preferably used. As a result of their crystalline structure, such swelling mattings are capable of filling up cavities by swelling as a result of water absorption.
It is also possible to compensate for the different strengths radially along the periphery of the honeycomb body if the support secti
Bruck Rolf
Maus Wolfgang
Emitec Gesellschaft für Emissions Technologie mbH
Greenberg Laurence A.
Griffin Steven P.
Ildebrando Christina
Lerner Herbert L.
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