GB2314034A

GB2314034A - Support and seal for a catalytic converter

Info

Publication number: GB2314034A
Application number: GB9612589A
Authority: GB
Inventors: Stephen Mark Forber; Gary Thomas Fisher; Paul David Francis
Original assignee: CATALYTIC SUPPORT SYST Ltd
Current assignee: CATALYTIC SUPPORT SYST Ltd
Priority date: 1996-06-15
Filing date: 1996-06-15
Publication date: 1997-12-17
Anticipated expiration: 2016-06-15
Also published as: GB2314034B; GB9612589D0; JPH1057819A

Abstract

A catalytic converter ceramic brick 18 is supported by sleeve 16, to which seals 12,14 are attached, one at each end. Preferably the seals are made by knitting a "sock" of metal wire, rolling it Up and compressing it.

Description

TITLE: A SEAL ASSEMBLY The present invention relates to a seal assembly.

In particular a seal assembly relating to the provision of seals for the rare earth coated ceramic brick/s which are commonly found in catalytic converters in the exhaust systems of vehicles.

These seals are also known as support rings, wire mesh rings and seals, seal rings and net ring edge protection.

It is well known that such ceramic bricks are brittle and are subject to breakage or fracture either during assembly of the vehicle exhaust system or during use of the vehicle. Measures have to be taken in the design of the mornings for the brick to reduce or eliminate the risk of a breakage or fracture of a brick during assembly and use. It is also necessary to provide means seal the bricks and thereby ensure that the exhaust gasses pass through the ceramic brick matrix rather than simply flowing through the space between the brick and the casing of the exhaust system.

These measures have usually comprised a pair of seals, one at each end of the brick or each brick, there usually being two bricks in a catalytic converter exhaust each provided with a winding of an intumescent material around the brick and located between the two end seals.

In manufacture, the two bricks and associated end seals and intumescent material are located within part of the exhaust casing and the remainder of the exhaust casing is pressed into position and the two parts of the casing are welded or otherwise secured together. Usually the seals are formed from a compressed knitted wire mesh which is compressible and protects the bricks during the exhaust assembly process. When the vehicle engine is operated the intumescent material expands into the space between the bricks and the exhaust casing. However until the engine reaches a certain temperature, and the intumescent material has expanded fully, the bricks are still free to move to some extent within the casing and damage is caused to the bricks even before the vehicle is used on the road.

Also it has been found that the seals can become displaced from the brick and cease to perform the proper sealing function.

The present invention seeks to provide a seal assembly so that the brick seals do not become displaced relative to the brick.

Accordingly the present invention provides a seal assembly more particularly for the ceramic bricks of a vehicle catalytic exhaust convertor comprising a pair of seals secured together in a spaced apart relationship by a sleeve.

Preferably the seals are each formed from a compressed knitted wire mesh. The knitted wire mesh can be formed from a sock of knitted wire material which is rolled up on itself to form a general toroidal shape which is then placed in a press and compressed to the desired shape eg. generally rectangular.

The connecting sleeve can be formed from a sock of knitted wire mesh but it can be manufactured from any suitable material.

The seals and the connecting sleeve can be attached to each other by rolling over each of the free ends of the sleeve over the respective seals, and twisting together the free ends of the metal threads of the sleeve to the body of the sleeve thereby retaining the seals onto the sleeve in a spaced apart relationship.

The sleeve and the end seals can be attached together by other methods, eg. spot welding, seam welding or stapling.

The present invention further provides an assembly for a catalytic convertor comprising a rare earth coated ceramic brick, a seal assembly as described above and a length of intumescent material wound around the brick and located between the two end seals. The sleeve of the seal assembly can be located over or under the intumescent material.

The present invention also comprises a catalytic converter exhaust apparatus including one or more ceramic bricks, the or each brick having a seal assembly as described above.

The present invention will now be more particularly described with reference to the accompanying drawings in which Fig 1 shows diagramatically one form of seal assembly according to the present invention, and Fig 2 shows diagramatically the seal assembly of Fig 1 mounted on a ceramic brick.

Referring to the drawings there is shown a seal assembly 10 comprising two end seals 12 and 14 and a connecting sleeve 16, the seal assembly being located on a rare earth coated ceramic brick 18 for use in a catalytic exhaust convertor.

Each seal 12 and 14 is formed from a compressed knitted wire mesh. Each seal is formed from a sock of knitted wire which can be single, double or multi-ply. The sock is rolled up on itself to form a generally toroidal shape. The rolled sock is then positioned in a shaped die and compressed to the required density and shape. Usually the seals are of a generally rectangular form but the cross section can be varied as required by providing an appropriately shaped die.

The two seals 12 and 14 are joined together by the connecting sleeve 16 which itself is in the form of a knitted wire sock which again can be single, double or multi-ply but it will be appreciated that at each end of the sock there will be the free ends of the metal threads. These free metal thread ends are turned over the respective seals 12 and 14 and the free thread ends are twisted on to the body of the sleeve 16 in order to retain the seals 12 and 14 on to the sleeve 16 in a spaced apart relationship.

The seal assembly 10 can then be located over the ceramic brick 18 shown in figure 2 and a length of intumescent material 20 is wound over the brick 18 and located between the seals 12 and 14.

It will be appreciated that in such an arrangement the seals 12 and 14 are retained in position by the sleeve 16. The sleeve 16 is held on to the ceramic brick 18 by the intumescent material 20.

The ceramic brick 18 can take a variety of cross sectional shapes and each of the seals 12 and 14 can be shaped to correspond with the respective brick by appropriate design of the pressed tool die in which the seals are formed.

Also the sleeve can adopt a variety of shapes since it is knitted on a circular knitting machine it is only necessary to match a diameter of the sleeve to the perimeter of the brick and the sleeve can therefore adopt the shape of the brick.

Claims

1. A seal assembly more particularly for the ceramic bricks of a vehicle type catalytic exhaust converter comprising a pair of seals secured together in a spaced apart relationship by a sleeve.

2. A seal assembly as claimed in claim 1 in which the seals are each formed from a compressed knitted wire mesh.

3. A seal assembly as claimed in claim 2 in which the knitted wire mesh is formed from a sock of knitted wire material which is rolled up upon itself to form a generally toroidal shape, the toroidal shape then being placed in a press and compressed to the desired shape.

4. A seal assembly as claimed in claim 3 in which the seals and sleeve are attached together by rolling over each of the free ends of the sleeve over the respective seals and twisting together the free ends of the metal threads of the sleeve to the body of the sleeve.

5. An assembly comprising a catalytic converter including a rare earth coated ceramic brick and a seal assembly as claimed in any one of the preceding claims together with a length of intumescent material wound around the brick and located between the seals.

6. A seal assembly constructed and arranged for use and operation substantially as herein described, and with reference to the accompanying drawing.

7. An assembly of a catalytic converter and seal assembly constructed and arranged substantially as herein described and with reference to the accompanying drawing.