JPS61241413A - Simple substance catalytic converter fixture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for the treatment of exhaust gas from an internal combustion engine, such as a catalytic converter.

More particularly, the present invention provides such devices and such monoliths that include as catalytic members a frangible ceramic monolith containing multiple channels in which catalytic material is deposited for interaction with the exhaust gas. It concerns an improved installation for.

BACKGROUND OF THE INVENTION Such monoliths can be composed of brittle refractory ceramic materials, such as, for example, aluminum oxide, silicon oxide, magnesium oxide, silicate zorcon, cordierite or silicon carbide. These ceramic materials provide a skeletal-shaped structure with many small channels. A small impact load is sufficient to crack or crush this unitary body.

Due to this fragility problem that exists when using this type of catalytic converter in automobiles where the ceramic unit is placed in the exhaust system connected to the exhaust system, the unit is subject to virtually no shock loads. Much effort has been expended on developing means for supporting a unitary body within its housing such that it is free from. Representative of such efforts are the following: U.S. Pat. is disclosed. The unitary body is supported by a felted layer or sleeve of ceramic fibers compressed between it and the shell. After assembly, the compressed layers of ceramic fiber material are applied with suitable liquid hardeners, binders and adhesives containing heat resistant materials such as water-based colloidal silica. The treated device is then dried in a manner that causes migration of the silica solids to the exposed ends of the ceramic fiber sleeve.

U.S. Pat. No. 5,876,384 is simply a stone protective jacket that includes highly heat resistant steel reinforcing means embedded in ceramic fibers and binder means that themselves include refractory mortar. Discloses a unitary catalyst unit that is resiliently mounted in the reactor casing by enclosing the unit. The unitary body is surrounded by a protective jacket consisting of an inner and an outer layer of ceramic or mineral fibers embedded in a heat-resistant mortar. A steel reinforcing strip is embedded between the ceramic fiber layers and grips both ceramic fiber layers.

US Patent No. 3.891j96 discloses an elastic holder for a single catalyst body. This holder consists of a metal corrugated tube which at the same time forms the outer wall of the exhaust pipe. The corrugated tube is provided with a mechanical bias that safely holds the single catalyst body and presses it against the end bearing. The unitary body is surrounded on its outer surface by an elastic, heat-resistant material in the form of a ceramic filling placed in the space between the corrugated tube and the catalyst body or its ceramic sleeve. The catalytic body can be bonded by a refractory cement to a ceramic league that serves to thermally insulate the corrugated tube from the exhaust gas.

U.S. Pat. No. 3,916,057 discloses a method for attaching unitary catalyst support elements using expandable sheet materials containing vermiculite or other expandable mica. Expandable sheet material functions as an elastic attachment material by expanding in-situ. The thermal stability and elasticity of the sheet after exfoliation compensates for the difference in thermal expansion between the metal container and the unitary body and is due to mechanical vibrations and irregularities in the metal or ceramic surface that are transmitted to the unitary unit and are susceptible to fraying. Absorbs forces that may be applied to a single object.

U.S. Pat. No. 4,048,363 discloses a tiered intumescent mat used to wrap a ceramic catalyst unit. Expansion of the expandable material in the mat after heating secures the unitary body in its housing or envelope.

U.S. Pat. No. 4,142,864 discloses the attachment of a catalytic ceramic unit by placing a resilient flexible ceramic fiber mat or blanket in the space between the catalytic unit and the inner surface of the casing. There is. The blanket is compressed by the installation of annular plug members inserted at both ends of the ceramic body between the ceramic body and the casing. The plug can be made of solid metal, wire mesh or hollow metal.

U.S. Patent Nos. 4.259.7 S 5 and 4,256;
No. 700 discloses a catalyst-coated ceramic unit supported in a sheet metal housing by both a wire mesh sleeve and an intumescent sleeve that are placed adjacently in a non-overlapping manner.

U.S. Pat. No. 4,269,807 discloses an installation for a ceramic catalyst unit in which the unit is surrounded by a blanket of woven wire mesh that is partially compressed along its entire length. On top of the woven wire mesh is a strip of hot expandable material containing ceramic fibers as a viscous cogging or paste within the matrix of the wire mesh.

Some of the structures disclosed include machining the ceramic monolith to remove inches from its diameter and covering it with a corresponding thickness of ceramic fiber, followed by surrounding it with a woven wire mesh.

U.S. Pat. No. 4,3G 5,992 discloses a flexible expanded sheet material suitable for use in mounting automotive catalytic converter units. These materials contain non-swelling ammonium ion exchange vermiculite flakes.

U.S. Pat. No. 4J28,187 discloses a resilient retainer for axially suspending a ceramic catalyst unitary within a housing. The unitary body is surrounded by a layer of heat resistant mineral fiber material. On the fibrous layer there is a jacket or sleeve of inorganic material with good thermal insulation properties. On the sleeve there is a damping element, for example 7 ohm, soot vest or glass fiber fleece, or a metal wire cushion, which extends into the housing over the entire length of the unit and serves as a damping element to suspend the unit elastically with its ceramic fiber jacket. There are layers of highly elastic materials, such as:

U.S. Pat. No. 4,335,077 discloses supporting a monolithic ceramic catalyst by an elastically deformable buffer ring or envelope. - In an embodiment, the unitary body is surrounded by a protective jacket of heat-resistant cement or the like reinforced with ceramic fibers. This protective jacket may be reinforced with metal in the form of wire mesh or the like. The protective jacket is circumferentially surrounded by a layer of soft mineral fibers compressed between the housing wall and the protective jacket.

U.S. Pat. No. 4,555,872 discloses the support of a ceramic catalyst unitary body by gas-tight means of a heat-resistant and expansive sheet material, such as vermiculite, quartz or asbestos, surrounding a portion of the unitary body. are doing. There is then a separation layer of generally cylindrical braided wire or elastic support disposed longitudinally between the unitary body and its casing to cushion external forces applied to the unitary body.

U.S. Pat. No. 4,425,504 discloses that the ceramic catalyst bodies are supported at their ends by elastic knots of expanded metal or braided braids of steel cloth or ceramic fibers and expanded metal or other known A catalytic converter is disclosed that is surrounded by a respective buffer layer of flame retardant, corrosion resistant cushioning material.

U.S. Pat. No. 4,452,945 is for a single catalyst body in which the annular space between the hose song and the catalyst body is filled with a heat-resistant mineral fiber material that prevents exhaust bypass and acts as a thermal insulator. discloses an elastic suspension. In another construction, the unitary body is surrounded by a layer of mineral fibers and a rigid sleeve of refractory metal is disposed over the layer of mineral fibers.

The annular space between the sleeve and the housing may be filled with ceramic fibers.

The above-described means for supporting ceramic catalyst units are industrially suitable for use in conjunction with gasoline-powered passenger vehicles. In this type of application, maximum converter temperatures are generally below 1600°F. Attempts are made to support ceramic monoliths in vehicles with relatively high gross vehicle mass (GVM) using materials such as those disclosed in U.S. Pat. Nos. 3,916,056 and 4,505,992. Occasionally, failures occur that appear to be due to fracture of the known expansible sheet material. One mode of failure observed is the disintegration of a ceramic unit; another mode of failure is fracture of the expanded sheet material and consequent sequential jamming of the next unit. Larger passenger cars can use a catalytic converter that includes two ceramic units. A relatively high gross vehicle weight (GVW) vehicle, such as a truck, may require four units arranged in series. Due to their high GVW,
Such operating conditions in zero-weight vehicles are such that the engines of such vehicles operate at a much higher proportion of their maximum power and at a much higher proportion of the operating time than in passenger car engines. Provides maximum catalytic converter temperatures well in excess of . Converter operating temperatures of 2000°F are not uncommon, and temperatures as high as 2500°F may be encountered.

Typical passenger car contact converter has been granted US Patent No. 914057
or 0.1 as described in No. 4,505,992.
Each ramic unitary supported by an expandable sheet material having a nominal thickness of 95 inches and a nominal density of 40 pcf is used. This material is compacted to a nominal thickness of 0.130 inches and a nominal density of 601 b/ft (cpaf) during installation of the ceramic monolith into its metal shell. Such structures can be G
VTI' cannot withstand the high operating temperatures often encountered in the driving cycle of vehicles. To overcome these drawbacks, it has been proposed to increase the total nominal thickness of the compressed intumescent layer, sometimes up to about 24 inches, and the nominal density to about 65-70 lb7ft''. Although this latter structure does not fail immediately, after a period of operation the layers of expanded sheet material adjacent to the catalytic converter will completely collapse, and such collapsed layers will, in turn, causes failure or blockage of the next unit, or continues to collapse until the prior compressive force is released and the unit is freed from its constraints within the envelope and self-destructs due to mechanical impact. This possibility arises.

BRIEF SUMMARY OF THE INVENTION A first object of the invention is to provide mass production and also
Provides an improved attachment for fragile ceramic catalyst units that is suitable and convenient for use in automotive internal combustion engine exhaust systems, particularly where converter operating temperatures of 2000°F or higher are expected. It's about doing.

According to the invention, this object is: α) a housing having an inlet at one end and an outlet at its opposite end, each through which exhaust air flows; b) an outer surface and an inlet end face of the housing at one end communicating with the inlet; a frangible ceramic monolith resiliently mounted within the housing having an outlet end face at its opposite end in communication with the outlet; C) a ceramic in contact with and overlying at least a portion of the outer surface of the monolith; and d) an expansion layer arranged between the housing and the ceramic fiber layer.

According to another aspect of the invention, α) a hollow metal housing having an inner surface and an inlet at one end and an outlet at the other end; b) an inlet end face in communication with the inlet end of the housing and an outlet end of the housing. C) a frangible gas permeable ceramic monolithic catalytic element resiliently mounted within the nozzle having an exit end face that is thermally insulating the catalytic element in spaced relation from the nozzle; and means for resiliently attaching; d) withstanding continuous exposure to temperatures of at least 2000° F. covering and contacting at least 70% of the outer surface of the catalytic element between the end faces of the catalytic element; A catalytic converter for purifying the exhaust gas of an internal combustion engine is provided, comprising at least one layer of expanded sheet material overlying the ceramic fiber layer and in contact with the housing.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings, numeral 10 generally indicates a catalytic converter. The catalytic converter 10 generally represents a tubular housing song made of two pieces of metal, such as high temperature steel. Housing 12 has an inlet 14 at one end and an outlet 15 (not shown) at the opposite end. The inlet 14 and the outlet 15 are given a suitable shape so that they can be fixed at their outer ends to a conduit in the exhaust system of an internal combustion engine. Device 10 contains a frangible ceramic unit 18 that is supported and restrained within housing 12 by layers 20, 22 and 25, described below. The unitary body 18 contains a number of gas permeable passageways extending axially from an inlet end face at one end to an outlet end face at the opposite end. Unitary body 18 is comprised of a suitable refractory or ceramic material of known style and configuration. The unitary body generally has an oval or circular cross-sectional shape.

In accordance with the present invention, the unitary body is at least about α2 inches apart from its housing.

The outer image 18 is surrounded by a layer 20 of ceramic fibers. For unitary operation at temperatures up to 2,000 °C, the ceramic fiber layer 20 has a nominal installed thickness of at least Q.03 inches and a nominal installed density of at least about 40 pcf. It is preferable. On this layer 20 of ceramic fibers is a layer 22.25 of expanded sheet material in contact with the ceramic layer 20 and the metal housing song 12. Preferably, the intumescent layer 22.23 has a nominal installed (compressed) thickness of at least about 0.2 inches and a nominal installed density of about 70 pci.

Layer 20 is preferably and conveniently in the form of ceramic fiber paper. However, other ceramic fiber forms such as blankets, mats or felts are also suitable, provided they can provide the necessary insulation and mechanical support, such as that provided by a layer of ceramic fiber paper. is available.

In FIG. 1, the intumescent material is added to the ceramic fiber layer 20
Although shown for use in the form of overlapping layers 22 and 23, a single layer of intumescent material may be used if it can provide the required thickness and density. The ceramic fiber paper can be laminated to the expansion layer before assembly as a catalyst device.

Ceramic fiber papers suitable for use in the present invention preferably do not contain vermiculite. A small amount of vermiculite, for example up to about 30 weight percent, may be present in the ceramic fiber paper layer; however, the presence of such vermiculite cannot be inferred and the This may reduce the operating temperature and life of a single-body catalytic converter using The presence of vermiculite, including ammonium ion exchange forms, can reduce the effectiveness of the ceramic fiber layer by causing degradation at lower temperatures, especially in ceramic fibers without vermiculite present.

A particularly suitable material for the ceramic fiber layer 20 for unit temperatures up to 2300°F is Fiber-7 Lux 97, commercially available from Socio Ensignado Materials, Inc., La All, NY.
0 paper is recognized. This product has approximately 50
It consists of bulky aluminosilicate glass fibers with a -50 alumina/silica and a 70/30 fiber/shot ratio. Approximately 93 weight percent of this paper product is ceramic fiber/shot, with the remainder being in the form of an organic latex binder. For higher unit temperatures, paper made from 7 Ipermax® polycrystalline mullite ceramic fibers available from the same manufacturer can be used.

Alumina fibers can also be used if high unit temperatures are expected.

In a typical device for use in a 2-10 ton truck, the ceramic body is circular in cross-section and has a diameter of about 6 inches and a length of about 3 inches. For converter configurations involving single bodies expected to operate at temperatures up to 2500'P, a nominal thickness before compaction of about α125 inches and about 12p6
A layer of Fibermax ■ ceramic fiber paper having a nominal density before compression of / is wrapped around each unitary spool. Thereafter, a nominal uncompressed thickness of about α200 inches and a thickness of about 4
No. 9, having a nominal uncompacted thickness of 0 p6f
Two layers of expandable sheet material, such as those described in US Pat. This unitary, ceramic fiber paper and expanded sheet material layer combination is then inserted into one of the members corresponding to those forming the housing 12. The assembly is then assembled between the housings to reduce the combined thickness of the ceramic fiber paper and expanded sheet material layers to about 50% inches and increase the density of the combined layers to about 701 b/ft". The ceramic fiber layer and the intumescent layer preferably span at least about 7Q cents of the length of the unitary in the longitudinal direction.The ceramic fiber and intumescent layer extend beyond the ends of the unitary. After compression of the members forming the housing, the edges are folded over or vertically welded as shown in FIG. 1 to form an airtight housing.

Although not completely clear, there appears to be a direct relationship between the density of the ceramic fiber paper layer and the expanded material layer and the maximum operating temperature of the catalyst device. For example, when the intended maximum annual operating temperature is approximately 1600°F, U.S. Pat.
Installations of about 45 to 60 pcf of vermiculite-containing expansive material alone according to No. 5.992 provide adequate longevity when used at densities. The maximum annual operating temperature is 1
When going up to 825″F, installation of such a layer of intumescent material can provide a reasonable service life when the density is about 70 cpf.

When the intended maximum service temperature of a unit is up to 2000° F., such expanded sheet material will have a 70 paf installation in density and an α240 installation in thickness.
Degrades when it comes into contact with a single object.

In the laboratory experiment, the installation thickness of α035 inch is 45p.
The installation of cf shows that the use of a dense ceramic fiber paper layer reduces the temperature at the interface of the ceramic fiber paper and such an intumescent sheet material by 10 to 114" Ftl. The ceramic fiber paper layer lowers the maximum temperature of the intumescent layer. Preferably, the thickness is sufficient to limit the temperature to less than 1900"F, and more preferably to 1850@F or less.

Although the subsequent increase or decrease in density of the ceramic fibers and intumescent materials does not significantly change the thermal insulation per unit thickness of these layers, the constraining forces exerted on the unitary body has a significant impact.

The binding force at 75°F increases in direct proportion to the increase in post density.

Although the presently preferred embodiments of this invention have been illustrated and described, it will be obvious to those skilled in the art that modifications thereof are within the spirit and scope of the invention. For example, the unitary body may be an electrically resistively heated element. A single body can act as a renewable particulate trap. For example, in assemblies where relatively high unitary operating temperatures, e.g.
In order to thermally insulate the radially outer layer of vermiculite-containing expansive material from temperatures exceeding the maximum continuous service temperature, it must be comprised of Fibermax® polycrystalline mullite fibers or alumina fibers. A single ceramic body is first wrapped with polycrystalline aluminosilicate fibers,
It is then wrapped with vitreous aluminosilicate fibers and then with expanded material. The outside temperature of the contact converter housing is
It can be reduced by increasing the combined thickness of the ceramic fiber and intumescent material layer.

For ease of illustration, housing 12 is shown as being smooth. However, for most applications, the housing 12 may be lipped or otherwise reinforced to make it durable to withstand the forces exerted by the compressed ceramic fiber paper and expanded sheet material. is preferred.

As used herein, "ceramic fiber" includes those comprised of basalt, industrial smelting slag, alumina, alumino-silicates, and chromium, zircon and calcium modified aluminosilicates, and the like.

[Brief explanation of the drawing]

FIG. 1 is a fragmentary isometric view of an apparatus embodying the invention.

Claims (1)

Claims: 1. a) a housing having an inlet at one end and an outlet at its opposite end, each through which exhaust air flows; b) an outer surface and an inlet end face at one end communicating with the inlet of the housing and the housing; c) a frangible ceramic unitary resiliently mounted within the housing having an outlet end face at its opposite end in communication with the outlet; c) contacting and causing at least a portion of the outer surface of the unitary body; A device for the treatment of exhaust gas from an internal combustion engine, comprising: a covering ceramic fiber layer; and d) an expansion layer disposed between the housing and the ceramic fiber layer. 2. The device of claim 1, wherein the ceramic fiber layer is selected from the group consisting of a ceramic fiber mat, a ceramic fiber blanket, a ceramic fiber felt, or a ceramic fiber paper. 3. The ceramic fiber layer is a ceramic fiber paper containing less than 30 percent vermiculite by weight;
An apparatus according to claim 1. 4. The device of claim 1, wherein the ceramic fiber layer is a vermiculite-free ceramic fiber paper. 5. Ceramic fiber paper has a maximum temperature of about 190℃ for the expanded layer when the single layer is at its highest intended continuous operating temperature.
of sufficient thickness to confine the temperature below 0°F;
An apparatus according to claim 3. 6. The ceramic fiber layer is of sufficient thickness to limit the maximum temperature of the interface between the intumescent layer and the ceramic fiber layer to less than 1850° F. when the unit is at its intended maximum continuous operating temperature. 2. A device according to claim 1, wherein the device is of the type described above. 7. Ceramic fiber paper shall have an installed nominal thickness of at least 0.035 inches and at least 40 lb/ft^2
4. The device of claim 3, having a nominal density installed. 8. The apparatus of claim 4, wherein the expansion layer contains ion-exchanged vermiculite and the ceramic fiber layer limits the maximum temperature of the expansion layer to less than 1850 degrees Fahrenheit during continuous treatment of the exhaust air. . 9. The apparatus of claim 8, wherein the intended operating temperature of the unitary body is greater than 1900°F. 10. The intended operating temperature of the unit is at least 1950°
9. The device according to claim 8, which is F. 11. a) a hollow metal housing having an inner surface and an inlet at one end and an outlet at the other end; b) an inlet end face communicating with the inlet of the housing and an outlet end face communicating with the outlet end of the housing; c) a frangible gas permeable ceramic monolithic catalyst element resiliently mounted within the housing; c) for resiliently mounting the catalyst element in a thermally insulating and spaced apart relationship from the housing; d) below
and e); d) at least 7 of the outer surface of the catalytic element between its end faces;
a layer of ceramic fibers capable of withstanding continuous exposure to temperatures of at least 2000°F overlaying and in contact with the housing; e) at least one layer overlaying the ceramic fiber layer and in contact with the housing; comprising an expanded sheet material;
Catalytic converter for purifying the exhaust gas of internal combustion engines. 12. The layer of ceramic fibers is a ceramic fiber mat;
Select from the group consisting of ceramic fiber blanket, ceramic fiber felt or ceramic fiber paper,
A catalytic converter according to claim 11. 13. The inner layer of ceramic fibers is at least 1/16
12. The catalytic converter of claim 11 having an uncompacted nominal thickness of inches and an uncompacted nominal density of at least 12 cpt. 14. The ceramic fiber layer has an attached nominal thickness of at least 0.030 inches and at least 40 lb/ft^3
Claim 11 having a nominal density attached to
Catalytic converter as described in section. 15. The catalytic converter of claim 14, wherein the catalyst unitary element is spaced at least about 0.2 inches from the housing. 16. The expanded sheet material has an uncompacted nominal thickness of about 0.4 inch, an uncompacted nominal density of about 40 cpf, and the attached ceramic fiber layer and expanded sheet material layer have a combined thickness of about 1/2 inch. 15. The catalytic converter of claim 14, having a combined density of about 70 cpf. 17. The catalytic converter of claim 13, wherein the expanded sheet material layer has an uncompacted nominal density of about 40 cpf. 18. The catalytic converter of claim 17 comprising two layers of expanded sheet material each having an uncompacted nominal thickness of about 0.2 inches. 19. The unitary element is about 93 weight percent about 70/
Wrapped in one layer of ceramic fiber paper containing ceramic fibers having a fiber/shot ratio of 30, the ceramic fibers being aluminosilicate glass fibers having an alumina content of about 50 weight percent, and the ceramic fiber paper having an alumina content of about 0.
．． 035 inch installed thickness and approximately 43 lb/ft^
3, and the expansion layer has an attached density of NH_4
^+ Treated in an aqueous ammonium solution until ion exchange with cations is substantially complete, from about 40 to about 6
5 weight percent unexpanded vermiculite flakes,
It includes two layers of material comprising about 25 to about 50 weight percent inorganic fiber material and about 5 to about 15 weight percent binder, the expansion layer exhibiting thermal expansion upon exposure to heat in excess of 350°C. 12. A catalytic converter according to claim 11. 20. a) Wrapping a layer of ceramic fiber paper around the unitary body between its inlet and outlet end faces; b) Assembling the unitary body wrapped with the layer of ceramic fiber paper with an expanded sheet material. and c) forming a housing around the assembly, in which the ceramic fiber paper and expanded sheet material are radially compressed between the unitary body and the housing. A method for mounting within a housing a gas permeable ceramic monolithic catalyst element having an inlet and an outlet end face.