Metal working – Method of mechanical manufacture – Catalytic device making
Reexamination Certificate
2000-07-27
2002-12-24
Hughes, S. Thomas (Department: 3726)
Metal working
Method of mechanical manufacture
Catalytic device making
C029S890054, C029S890080, C029S522100, C029S525140, C029S527100, C156S293000, C156S294000, C228S181000
Reexamination Certificate
active
06497039
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a method of producing an encased honeycomb body.
Honeycomb bodies, which are produced by stacking and/or winding layers of sheet metal, of which at least some are structured layers of sheet metal, are known in a wide variety of forms. Honeycomb bodies including metal sheets are used as so-called support structures for catalytically acting coatings. Support structures of this type, with a catalytically acting coating, are used in motor-vehicle exhaust systems, thereby reducing the emission of certain components of the exhaust gas. Different forms of a configuration as a catalyst support structure are described, for example, in Published European Patent Application EP-A1-0 245 738.
The stacked and/or wound layers of sheet metal are at least partially soldered to one another, so that the honeycomb body is a monolithic structure. The honeycomb body is also soldered to the tubular jacket in which the honeycomb body is located. Soldering of the layers of sheet metal to one another and to the tubular jacket preferably takes place in one soldering operation. Methods of soldering a metallic configuration, including a honeycomb body and a tubular jacket, are known for example from International Publication Nos. WO89/11938, WO94/06594, WO93/25339 and from Published, Non-Prosecuted German Patent Application DE-A-29 24 592.
It is known from the prior art that the honeycomb body is provided at least partially with a bonding agent, to which a soldering powder adheres. The methods known from the prior art differ from one another with respect to the sequence of applying a soldering powder bonding agent, namely during or after the forming of the honeycomb body. A detailed account of the prior art in this respect is includes in International Publication No. WO89/11938.
The various ways of conducting the method with respect to the soldering of a configuration have various advantages. However, for the cost-effective production of a configuration it is desired to obtain a soldering method in which on the one hand a solder is introduced only into the regions in which a soldered connection is to be created, on the other hand the soldering operation is to take place as quickly as possible and with relatively little effort.
If the configuration including a honeycomb body provided in a tubular jacket is used as a catalyst support structure in an exhaust system, this configuration is subjected to thermal loading or stress. The honeycomb body and the tubular jacket have different thermal expansion characteristics on account of their different material properties. It is therefore desirable to avoid a rigid connection between the honeycomb body and the tubular jacket at at least an end region of the honeycomb body. If there are no rigid connections to the tubular jacket in the respective end regions of the honeycomb body, thermal stresses between the tubular jacket and the honeycomb body are avoided.
It is already known from International Publication No. WO96/26805 that thermal stresses can be avoided by a suitable soldering of the honeycomb body to the tubular jacket. According to International Publication No. WO96/26805, it is proposed that at least one layer of sheet metal of the honeycomb body has at least one smooth portion extending from a least one end face over part of the axial length of the honeycomb body and at least partially surrounding the honeycomb body. The smooth portion forms at the periphery of the honeycomb body an outer layer which bears against the tubular jacket. This achieves the effect that, irrespective of the soldering method, no solder gets between the outer layer and the tubular jacket. The solder can therefore be applied in the way known from the prior art. The connection of the honeycomb body to the tubular jacket takes place over part of the axial length of the tubular jacket, the smooth portion extending in the axial direction of the honeycomb body only up to the connecting region between the honeycomb body and the tubular jacket.
On account of production tolerances of the tubular jacket and the honeycomb body, however, it cannot be ensured that no solder will get between the smooth layer and the tubular jacket. To avoid the outer layers of the honeycomb body becoming connected to the tubular jacket, it is already known that the honeycomb body can be soldered through corresponding masks which cover the outer region of the honeycomb body. As a result, a connection of the outer region of the sheet-metal layers to the tubular jacket is avoided. In particular in the case of honeycomb bodies wound in an S-shaped manner, such unconnected outer regions of the layers of sheet metal cause these end regions of the layers of sheet metal to be prone to oscillate during the operation of the catalyst support structure in an exhaust system. The oscillations of the end regions may cause a destruction of the catalytically effective coating of the metallic honeycomb body.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method of producing an encased honeycomb body, in particular a catalyst support structure, which overcomes the above-mentioned disadvantages of the heretofore-known methods of this general type.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method of producing an encased honeycomb body, which includes the steps of:
forming a honeycomb body by stacking and/or winding layers of sheet metal and providing at least some of the layers of sheet metal as structured layers of sheet metal such that the honeycomb body is formed with channels for a fluid to flow therethrough;
introducing a sleeve into a tubular jacket and providing the sleeve with an axial extent of less than an axial length of the honeycomb body and of the tubular jacket and providing the sleeve with an outer circumferential surface essentially bearing against a part of an inside wall of the tubular jacket;
introducing the honeycomb body into the tubular jacket and into the sleeve; and
forming a connection between the honeycomb body and the tubular jacket and a further connection between the honeycomb body and the sleeve.
In other words, the method according to the invention of producing an encased honeycomb body includes forming a honeycomb body by stacking and/or winding layers of sheet metal, of which at least some are structured layers of sheet metal, so that the honeycomb body has channels through which a fluid can flow. At least one sleeve, which forms a bushing-shaped spacer, is introduced into a provided tubular jacket. The axial extent of the sleeve is less than the axial length of the honeycomb body and of the tubular jacket; the sleeve is preferably introduced in the region of one end face of the tubular jacket. The honeycomb body is introduced into the tubular jacket prepared in this way. The honeycomb body overlaps the tubular jacket and the sleeve. This is followed by forming a connection between the honeycomb body, the tubular jacket and the sleeve, so that the honeycomb body is connected to the tubular jacket and the sleeve. If appropriate, a connection is also formed between the tubular jacket and the sleeve. The sleeve prevents the end regions of the honeycomb body from being connected directly to the tubular jacket. The fact that the honeycomb body is connected to the sleeve achieves the effect that the sleeve forms a compensating element, compensating for the different thermal expansions of the tubular jacket and honeycomb body, and a rigid connection with the tubular jacket is not created in the at least one end region of the honeycomb body.
For technical production-related reasons, a tubular jacket has a certain circularity error with regard to it roundness. There are also tolerances with regard to the variations of an inside diameter of the jacket. As a result of this, a gap may form between the inside wall of the tubular jacket and the sleeve. To avoid solder getting into this gap, and thus creating a rigid connection between t
Grewe Heribert
Kurth Ferdi
Siepmann Uwe
Wieres Ludwig
Emitec Gesellschaft fuer Emissions-technologie mbH
Greenberg Laurence A.
Hughes S. Thomas
Mayback Gregory L.
Nguyen T.
LandOfFree
Method of producing an encased honeycomb body does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of producing an encased honeycomb body, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of producing an encased honeycomb body will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2975405