DE2220921C2 - DEVICE FOR CATALYTIC CLEANING OF EXHAUST GASES FROM COMBUSTION MACHINES - Google Patents

Description

The invention relates to a device for catalytic Purification of the exhaust gases from internal combustion engines, in which the catalyst body Gas-tight in a metal housing via rings made of flexible, non-flammable material is mounted on the face and on the circumference.

In a known device of this type (German Auslegeschrift 1 476 507) that is an outer protective cover Catalyst bodies made of fibrous aluminum silicate on the inner surface of the housing wall supported over a resilient corrugated part on its entire circumference; in the direction of flow it is held at the front by inwardly facing annular housing flanges.

This type of storage of the known catalyst body is pretty tough overall; this applies in particular to those running in the direction of flow Bumps. An application of the known storage of the catalyst body in exhaust systems on passenger cars, or wherever strong gas-dynamic or external influences Impacts occur can quickly lead to destruction of the catalyst body, as suitable

ίο catalysts made from very brittle, easily fragile Materials.

According to an older proposal, one or more rings made of mineral fibers are between the catalyst bodies and housing inner wall pressed in, which ensure a good shock-absorbing effect.

The invention is based on the object of keeping the catalyst body in the interior of a housing store, so that it can withstand extreme shock loads over the long term.

According to the invention, this object is achieved by that the housing is double-walled, with one of an outer wall a radial Spaced inner wall, which by means of the rings opposite the front ends of the

»5 catalyst body is supported while the outer wall at least opposite the ends of the inner wall located outside of said support miUels end rings made of the said material is supported, all rings by the selected dimensions are at least under radial tension.

The invention is based on the idea of occurring shocks over as long as possible and attenuated To transmit paths between the housing walls and the catalyst body. According to the invention should not only provide a direct support between the catalyst body and the housing wall, as z. B. with the Flanging is provided in the known device. \ be avoided; it should also can still be avoided, bumps between the housing wall and the catalyst body in a direct way to transmit suitable damping elements, such as that provided for in the older proposal. After Rather, such damping elements act together with parts of the inner wall or the outer wall of the housing. When the impact is initiated, the vibrations are carried through the elastic deformation of the walls reduced so that in the support points of the inner wall opposite the oscillation amplitudes of the catalyst body are only very low.

For better securing the position of the inner wall opposite the outer wall, the invention proposes that the inner wall and outer wall still on at least one another point between the end faces of the catalyst body against each other by means of an intermediate ring are supported. The length of the effective damping path is determined by such an intermediate ring not shortened between the rings or end rings.

In the case of particularly long catalytic converter housings, a plurality of intermediate rings will preferably be attached.

It is advantageous to keep the number of intermediate rings as small as possible and only one if possible To arrange intermediate ring in the middle between the end faces of the catalyst body. The damping effect can be increased by the fact that the inner wall and / or the outer wall in the area of the intermediate ring is interrupted and overlap

pende, having interconnected ends pressing against the intermediate ring.

To improve the hold of the rings, end rings or intermediate rings, the invention proposes that one or more rings, end rings or intermediate rings in a form-fitting manner with the inner wall and / or the Outer wall and / or the circumferential surface of the catalyst body are arranged interacting.

When using rigid housing walls, e.g. B. thick-walled sheet metal walls, it is used to promote the Damping effect advantageous that the inner wall is parallel to the direction of flow through the catalyst body has running slots.

Of course, the various rings or packings must be made gas-tight so that the entire Exhaust gas flows through the catalyst body.

In the context of the invention it is possible to use the outer wall and / or inner wall of the housing of the catalyst body each split in a certain plane and the housing hips in the respective Ter'fuge to connect with each other. It is essential that that the said housing halves are dimensioned so that after their connection, the different Rings are under radial tension, with an axial tension component in addition to the radial tension can occur due to the corresponding action of axial housing forces.

An embodiment of the invention is shown in two sections in the drawing. It shows

1 shows an axial half section through the device according to the invention,

2 shows a cross section according to H-II of FIG.

According to FIGS. 1 and 2, the catalytic converter body 1 is traversed in the direction of arrow P by the exhaust gases to be detoxified. The catalyst body 1 consists of a brittle, refractory ceramic material, for example of magnesium silicate, aluminum oxide or the like. Its sensitivity to impacts is further increased by the fact that a large number of small flow channels are formed in it, so that it has a skeletal structure. Depending on whether it is an oxidation or a reduction catalyst, the structure has a coating made of a material suitable for the catalytic effect to be achieved. For an oxidation catalyst, for example, refractory metal oxides or metals such as platinum, rhodium or the like come into consideration.

The catalyst body is for its protection and so that it can be grasped at all without the risk of breakage 1 surrounded by a protective jacket 2, e.g. B. from a heat-resistant cement or a putty, which essentially consist of fluffy, chemically stable incombustible mineral fibers, essentially consists of aluminum oxide and silicon oxide with an added binder.

The protective jacket 2 is bordered at its ends on its entire circumference by rings 3a, 3b . These rings, like the end rings 4a, 4b and the intermediate ring 5, which are each arranged between the outer wall 6 and the inner wall 7 of the housing, consist of resilient, heat-resistant mineral fibers. In the rings, the mineral fibers are preferably compressed to such an extent that they assume a certain compression shape. This gives the rings a high level of elasticity, which is permanently maintained even at high temperatures. the

Ao rings 3a, 3b, 4a, 4b, 5 can be surrounded by a wire mesh or reinforced with a wire mesh, preferably using a wire that is softer than alloy components containing chromium, aluminum and / or cobalt.

The housing walls themselves consist preferably of a nickel-chromium alloy steel with an austenitic structure, which is heat and scaling-resistant ^{up to 115O 0 C.}

To simplify assembly, the housing walls 6 and 7 are each made of two parts, the inner ends of the parts overlap in the area of the intermediate ring 5 at 8 or 9 and by spot welding are connected to each other.

Vibrations of the housing parts, which occur, for example, in the area of the intermediate ring, plant themselves with decreasing amplitude in the outer wall 6 up to the end rings 4a, 4b, in the inner wall 7 up to the rings 3a, 3b. In this way, when impacts occur, damping distances of at least half the length of the catalyst body are achieved until the remaining residual oscillation is introduced via the rings 3a, 3b into the protective jacket 2 in the area of its end ribs 10i ?, 10i. The end ribs 10α, 1OA engage in the rings 3a, 3b in a form-fitting manner.

In FIG. 2, for the sake of clarity of the illustration, hatching of the cut parts as well of the intermediate ring 5 is omitted.

1 sheet of drawings

Claims (6)

Patent claims: 1. Device for the catalytic cleaning of the exhaust gases from internal combustion engines, in which the catalyst body is mounted gas-tight on rings made of flexible, non-flammable material in a metal housing at the end and on the periphery, characterized in that the housing is double-walled, with one of an outer wall (6) having a radial spacing, coaxial inner wall (7) which is supported by means of the rings (3a, 3b) opposite the front ends (at 10a, IQb) of the catalyst body (1), while the outer wall (6) is at least opposite the ends of the inner wall (7) located outside of said support are supported by means of end rings (4a, 4b) made of said material, all rings being at least under radial tension due to the selected dimensions. 2. Apparatus according to claim 1, characterized in that the inner wall (7) and outer wall (6) at at least one other point between the end faces of the catalyst body (1) are supported against each other by means of an intermediate ring (5). 3. Apparatus according to claim 2, characterized in that the intermediate ring (S) in the Center between the end faces of the catalyst body (1) is arranged. 4. Apparatus according to claim 3, characterized in that the inner wall (7) in the area of the intermediate ring (5) is interrupted and overlapping, pressing against the intermediate ring, optionally having interconnected ends (at 8). 5. Device according to one of claims 1 to 4, characterized in that one or more rings (3a, 36) end rings (4a, Ab) or intermediate rings (5) form-locking with the inner wall (7) and / or the outer wall (6 ) and / or the circumferential surface of the catalyst body (1) are arranged interacting. 6. Device according to one of claims 1 to 5, characterized in that the inner wall (7) has slots extending parallel to the flow direction [P) of the catalyst body (1).