MXPA98010511A - Hybrid assembly system for devices for contamination control - Google Patents

Abstract

A device for controlling contamination has a metallic housing (12), a pollution control device (20) placed inside the metallic housing, and a mounting grid (24) placed between the control element of the device. pollution and housing to place the element for pollution control and to absorb the mechanical and thermal shock. The mounting grid includes a layer of intumescent material (26) having at least one insert formed of a material that is elastic, flexible, fibrous, non-intumescent (28). The insert is located at least one portion of at least one side edge of the mounting grid to prevent erosion of the intumescent material and to provide a seal between the element for contamination control and the housing.

Description

HYBRID ASSEMBLY SYSTEM FOR DEVICES FOR THE CONTROL OF POLLUTION BACKGROUND OF THE INVENTION The present invention relates to devices for the control of contamination, and particularly with catalytic converters and filters or diesel particle traps for an automotive exhaust system. Pollution control devices typically comprise a metal housing with a monolithic element - securely mounted within the frame by means of an elastic and flexible mounting grid or mesh. The mounting grid or mesh is comprised of an intumescent sheet material having inserts formed of a non-intumescent ceramic fiber composition. Pollution control devices are universally used in motor vehicles to control air pollution. Two types of devices are currently in widespread use - catalytic converters and filters or diesel particle traps. The catalytic converters contain a catalyst, which is typically coated on a monolithic structure mounted on the converter. The monolithic structures are typically ceramic, although metal monoliths have also been used. The REF. 29021 Catalyst oxidizes carbon monoxide and hydrocarbons, and reduces nitrogen oxides in automobile exhaust gases to control air pollution. Due to the relatively high temperatures found in these catalytic processes, ceramics have been the natural choice for catalyst supports. Particularly useful catalyst supports are provided by ceramic honeycomb structures as described, for example, in US Patent Re. 27,747. More recently, they have also been used to catalytic converters that use metallic catalyst supports (metal monoliths) for this purpose.

(See, for example, in British Patent No. 1,452,982, U.S. Patent No. 4,381,590 and SAE 850131). The most common diesel particle filters or traps are monolithic wall flow filters. These monolithic wall-flow type diesel particulate filter elements are typically comprised of porous, porous, crystalline (e.g., cordierite) ceramic material. The alternating cells of the honeycomb structure are typically obstructed so that the exhaust gas enters a cell and is forced through the porous wall of one cell and leaves the structure through another cell. The size of the diesel particulate filter element depends on the particular application needs. The useful diesel particulate filter elements are commercially available, for example, from Corning Inc. of Corning, New York, and NGK Insulator Ltd. of Nagoya, Japan. Useful diesel particulate filter elements are discussed in Cellular Ceramic Diesel Particulate Filter, "Howitt et al., Article No. 810114, SAE Technical Series, 1981. In the state of the art of construction of these devices, each type of device has a metal housing, which houses within it a monolithic structure or element that can be made of metal or ceramic, and more commonly of ceramic.The monolithic structure is mounted in a housing with a known process There is a gap or space between the monolith and the housing which varies because there is a range of size tolerances for both the monolith and the housing.There is a larger space when the monolith is on the small end of the interval and the housing is on the large end of the interval.To avoid damage to the monolith and to keep it in place typically a mounting material is deposited, such as an intumescent mounting grid or mesh or an intumescent paste, around the monolith before canning. The mounting material fills the space. After the rolled monolith is inserted into the housing, the can is pressed closed and the ridges along the side edges of the housing are welded. After installation in the vehicle, the pollution control device is heated by the hot exhaust gases, which expand the intumescent materials generating an additional retention pressure. The amount of pressure is determined by the density of the assembly of the materials and the temperatures of use. If the mounting density is too low, there will be insufficient pressure w to hold the monolith in place. If the density of the assembly is too high, excessive pressure can be exerted by the mounting material between the housing and the monolith causing deformation of the housing and / or damage to the monolith. After the monolith has been secured in the housing, the intumescent mounting material serves to prevent or reduce damage to other conditions that may be problematic to the device for controlling contamination. The device can be subjected to harmful vibrations both before and after installation in a vehicle. Additionally, the entire device is subjected to high temperatures, for example of more than 300 C, for several periods of time.

A ceramic monolith has a coefficient of thermal expansion generally of the order of magnitude less than that of the metal housing (usually stainless steel) in which it is contained, so that at elevated temperatures, the mounting material must expand sufficiently to be compensated by the differential expansion, but not too much to create excessive pressure, which can damage the housing or the monolith. The mounting material also prevents hot exhaust gases from passing between the monolith and the metal housing (thus avoiding the catalyst). Typically, the assembly materials include organic binders, inorganic fibers which may also serve as binders, intumescent materials, and optionally, organic binders, fillers and other adjuvants. The materials are used as pastes, sheets and meshes. Ceramic mesh materials, ceramic pastes and intumescent sheet materials useful for mounting the monolith in the housing are described in, for example, US Patent Nos. 3,916,057 (Hatch et al.), 4,305,992 (Langer et al. ), 4,385,135 (Langer et al.), 5,252,416 (Langer et al.), 5,242,871 (Hashi oto et al.), 3,001,571 (Hatch), 5,385,873 (MacNeil), 5,207,989 (MacNeil), and British Patent No. 1,522,646 ( Wood).

U.S. Patent No. 4,999,168 to TenEyck discloses a rupture resistant intumescent sheet having the preformed intumescent layer adhesively bonded to a reinforcing layer of a sheet material such as craft paper, plastic film, inorganic fabric. U.S. Patent No. 4,865,818 to Merry et al. , discloses a method for producing a catalytic converter by winding a thin sheet of mesh material around the monolith at least twice in a layer in a prudent manner. US Patent No. 4,929,429 to Merry discloses a composition for catalytic converters having a ceramic fiber mesh stitched to an intumescent mesh material. U.S. Patent No. 4,048,363 to Langer et al., Discloses a composition having at least two layers of similar sheets of intumescent materials. Since the device for controlling contamination typically ranges from high to low temperatures, the size of the space between the monolith (metal or ceramic) and the housing continuously changes, the mounting grid or mesh is compressed and decompressed repeatedly. In cases where the housing reaches very high temperatures, i.e. of more than about 700 ° C, deformation of the housing can occur. In those cases, the conventional intumescent mesh mounting material may lack high-temperature elasticity to continue providing the monolith support. Thus, there is a need for a mounting system that is sufficiently resilient and compressible to accommodate the changing space in the monolith and metal housing without causing deformation of the metal housing. In addition, although the prior art assembly materials have their own utilities and advantages, there remains a current need to provide assembly materials for use in a device for the control of contamination.

Additionally, it will be desired to provide materials that function well over a wide temperature range.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a hybrid mounting system for devices for the control of contamination, which uses a monolithic structure within a metal housing. The mounting system comprises a mounting grid or mesh placed between the monolith and the metal housing of the device for controlling the contamination. The mounting grid or mesh includes inserts formed of an elastic, flexible, fibrous non-intumescent material positioned along a side edge of the grid or mounting mesh. In a preferred mode, the grid or mounting mesh is an intumescent material, and the elastic, flexible, fibrous insert is formed of a non-intumescent material. Hybrid mounting mesh is useful for protecting fragile monolithic structures in catalytic converters, diesel particle filters and high temperature filters. The hybrid mounting mesh offers the advantage of being able to combine the properties of intumescent mounting mesh and non-intumescent inserts. to BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an exploded perspective view of a catalytic converter showing the mounting system of the present invention. Figure 2 is a view of the catalytic converter of Figure 1, showing a mounting system of the present invention detached from the monolith. Figure 3A shows a joining system of the prior art comprised of an intumescent material. Figure 3B shows the assembly system of Figure 3A placed around a monolith in cross section.

Figure 4A shows a preferred embodiment of the mounting system of the present invention. Figure 4B shows the mounting system of Figure 4A placed around a monolith in cross section. Figure 4C shows a modification of the mounting system of Figure 4A. Figure 5A shows an alternative embodiment of a mounting system of the present invention. Figure 5B shows the mounting system of Figure 5A placed around a monolith in cross section. Figure 6A shows an alternative embodiment of a mounting system of the present invention. Figure 6B shows the assembly system of the Figure 6A placed around a monolith in cross section. Figure 7A shows an alternative embodiment of a mounting system of the present invention. Figure 7B shows the assembly system of the Figure 7A placed around a monolith in cross section. Figure 8A shows an alternative embodiment of the mounting system of the present invention.

Figure 8B shows the mounting system of Figure 8A placed around a monolith in cross section. Figure 9 shows an alternative embodiment of a catalytic converter having a dual monolith. Figure 10 shows an alternative embodiment of the mounting system of the present invention. Figure 11 shows yet another alternative embodiment of the mounting system of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Although the mounting system of the present invention is suitable for use in a variety of pollution control devices, such as catalytic converters and diesel particulate filters or traps, its use is described here in with a catalytic converter. The description is intended to be illustrative of the use of the mounting system of the present invention and should not be construed as limiting the use of the assembly system of the catalytic converters. Referring now to Figures 1 and 2, the catalytic converter 10 comprises the metallic housing 12 with a generally conical entrance 14 and an outlet 16. The housing, which is also known as a can or case, can be made of suitable materials known in US Pat. the H technique for such use and is typically made of metal. Preferably, the housing is made of stainless steel. Deposited within the housing 12 is a monolithic catalytic element 20 formed of a honeycomb monolithic body either ceramic or metal. Suitable catalytic converter elements, also known as monoliths, are known in the art and include those made of metal and ceramic. The monoliths or elements are used to support the catalytic materials for the converter. A converter element a. useful catalytic is described, for example, in the Patent American No. RE 27,747 (Johnsorí). The monolith 20 has a plurality of gas flow channels (not shown) therethrough. Catalyst materials coated on the elements of the catalytic converter include those known in the art (for example, metals such as ruthenium, osmium, rhodium, iridium, nickel, palladium and platinum, and metal oxides such as vanadium pentoxide and dioxide). titanium tie). For additional details related to catalytic coatings see, for example, U.S. Patent No. 3,44,131 (Keith et al.). Surrounding the monolith 20 is the hybrid mounting system 24. The mounting system 24 comprises a grid or mesh 26 of intumescent material having inserts 28 formed of an elastic, flexible, fibrous mesh of ceramic fiber essentially free of particles. The inserts 28 are positioned so that at least one edge of the insert 28 extends along a side edge of the intumescent mesh 26. As seen in Figures 4A-8B, there are numerous ways in which the insert 28 can be positioned so as to extend along the side edge of the intumescent mesh 26. Figures 3A and 3B illustrate an intumescent mesh 26 without insert 28. Figure 3B provides a cross-sectional view of an intumescent mesh 26 placed between the case 12 and the monolith . Figure 4A shows the non-intumescent inserts 28 alternating with the intumescent mesh 26, so that the lateral edge 32 of the mounting system 24 has alternating sections of intumescent and non-intumescent material. Figure 4C shows a modification of the mounting system 24 in which each mesh or grid 26 and the insert 28 are formed with a tongue 30 at one end and a groove 31 at the other. The tongue 30 of each mesh 26 is placed in or engages with the slot 31 of an adjacent insert 28. Similarly, the tongue 30 of each insert 28 is placed in or engages with the slot 31 of an adjacent mesh 26. In the illustrated embodiment, each tab 30 is of the same size and each slot 31 is of the same size. It may be desirable that the tab 30 of each mesh 26 be dimensioned so that it only engages the slot 31 of an insert 28 and that the tab 30 of each insert 28 is dimensioned so that it only engages with the slot 31 of the insert. 26. It should be understood that the mounting system 24 could be modified in addition to numerous ways to accommodate other types of monoliths and cases not described herein, including reducing or increasing the number of each type of section and changing the shape of one or more sections used for the mounting system 24. The use of different slot and tongue arrangements may also be desirable. As illustrated in Figure 4B, when the mounting system 24 is placed around the monolith 20 within the case 12, the non-intumescent inserts 28 are preferably placed along the portion of the monolith 20 having the largest radius of curvature . The inserts 28 are preferably positioned along the portion of the monolith 20 having the largest radius of curvature because this area corresponds to the portion of the case that is most likely to deform under excessive pressure caused by compression of the system. assembly 24. As noted above, in cases where the device for controlling the contamination reaches very high temperatures, that is to say, of more than about 700 ° C, deformation of the housing can occur. At these high temperatures, the conventional intumescent mounting materials are greatly expanded, and the resulting pressure exerted on the interior of the case 12 is very high. In addition, at such high temperatures the case metal (typically stainless steel) begins to soften and becomes more susceptible to deformation. By placing non-intumescent inserts 28 at the points most likely to undergo deformation under high temperature conditions, the mounting system 24 generates less damaging forces at high temperatures, so that the deformation of the > Case is greatly reduced. Figures 5A and 5B show an embodiment of the mounting system 24 similar to that of Figures 4A and 4B. In the embodiment of Figures 5A and 5B, the inserts 28 do not extend across the width of the grid or intumescent mesh 26. When placed around the monolith 20, the non-intumescent inserts 28 are placed in a manner similar to that described previously for Figure 4B. Figures 6A and 6B show yet another alternative embodiment of the mounting system 24 in which the non-intumescent inserts 28 extend along the entire side edge 34 of the intumescent sheet material 26 so that when the mounting system 24 is placed around the monolith 20, the entire side edge 34 of the intumescent sheet material 26 is protected by the insert 28. Yet another embodiment of the mounting system 24 is shown in Figures 7A and 7B. In Figure 7A, the mounting system 24 is shown including the inserts 28 which extend along the side edges 34 of the intumescent sheet material 26, but are deviated from the intumescent sheet material to form the tab configuration and groove observed as if it were a sheet of intumescent material 26 and non-intumescent material 28. a Finally, another modality of the assembly system 24 is shown in Figures 8A and 8ET. The mounting system of Figures 8A and 8B is similar to the mounting system of Figures 7A and 7B, but the insert 28 extends only along a side edge 34 of the intumescent sheet material 26. The insert 28 is offset of the intumescent sheet material 26 to form entanglement ends. In each of the embodiments of Figures 4A-8B, the inserts 28 can be secured to the grid or intumescent mesh 26 by means of an adhesive tape (not shown), such as a packaging tape or other suitable adhesive tape. Alternatively, the inserts 28 do not have to be secured with tape or can be secured by other techniques such as stapling, sewing, and the like.

In some cases, a device for pollution control can use two monoliths, instead of a single monolith. For example, Figure 9 shows a prior art catalytic converter 10A which has two monoliths 20 inside a metal housing 12 and which are separated by a space 40. In such a double monolith configuration, it is known how to align a strip of metal 42 with space 40 between monoliths 20. (See, for example, German Patent DE 43 23 791 A1). The metal strip is typically made of metals resistant to high temperature corrosion such as Inconel and stainless steel. The metal strip can take the form of a thin sheet of metal, thin sheet of corrugated metal, a metal cloth and the like. The metal strip 42 expands at a speed very close to that of the metal housing 12. Because the metal strip 42 expands at a rate similar to that of the housing 12, the portion of the mounting mesh 44 between metal strip 42 and the housing 12 tends to be compressed to a greater degree than the portion of the mounting mesh 44 between the monoliths 20 and the housing 12. If the portion of the mounting mesh 44 between the metal strip and the housing 12 is compressed excessively, deformation of either the housing 12 or the metal strip 42 may result.

As seen in Figure 9, prior art mounting meshes typically provided a continuous layer of mounting mesh 44 between metal strip 42 and housing 12. As described above, this arrangement can lead to deformation of the structure. housing 12 or the metal strip 42. It is therefore desirable to place a flexible, elastic fibrous insert 48 along the metal strip 42 between the metal strip 42 and the housing 12. Preferably, the insert 48 is a material such as SAFFIL, available from ICI Chemicals and Polymers. As discussed above, such inserts are capable of being compressed with less force than that typically used for mounting materials, so that deformation of case 12 or metal strip 42 is avoided. Figures 10 and 11 show alternative embodiments of the invention. assembly system of Figure 9 which utilizes a flexible, flexible, non-intumescent fibrous insert placed along the metal strip 42 between the metal strip 42 and the housing 12. In Figure 10, the metal strip 42 is inserted into directed portions 50 of the mounting mesh 44, and the insert 48 is secured adjacent the metal strip 42 with adhesive tape 52. In Figure 11, the metal strip 42 is sandwiched between the layers of the mesh assembly 44A and 44B (so that rotation of the mounting mesh material is not required). The flexible, elastic fibrous insert 48 is then inserted between the portions of the mounting mesh 44B and secured in place with adhesive tape 52. Either of the embodiments of Figure 10 or Figure 11 prevent excessive compression of the material between the strip of metal 42 and housing 12, and thus prevent deformation of metal strip 42 or housing 12. In use, the mounting materials of the invention are placed between the monolith and the housing in a similar manner for a converter catalytic or for a diesel particulate filter. This can be done by rolling the monolith with a sheet of the mounting material, inserting the rolled monolith into the housing, and welding the housing. The mounting system 24 holds the catalytic monolith 20 in place in the case 12 and seals the space between the catalytic monolith 20 and the case 12, thereby preventing the exhaust gases from escaping the catalytic monolith 20. The material of intumescent sheet 26 comprises an elastic, flexible intumescent sheet, comprising from about 20 to 65 weight percent of unexpanded vermiculite lamellae, such lamellae which may be untreated or treated by ion exchange with ammonium compounds such as phosphate ammonium acid, ammonium carbonate, ammonium chloride or other suitable ammonium compounds; from about 10 percent to 50 percent by weight of the inorganic fibrous material including the aluminosilicate fibers (commercially available under the names of Fiberfrax ™ from Unifrax Co., Niagara Falls, New York, and Cerafiber ™ from Thermal Ceraics, Augusta, Georgia), asbestos fibers, glass fibers, zirconium-siliceous, and crystalline alumina fibrils; from about 3 to 25 weight percent of binder including natural rubber meshes, styrene-butadiene lamellae, butadiene acrylonitrile meshes, acrylate or methacrylate polymer meshes and copolymers and the like; and up to about 40 percent e? weight of inorganic filler including expanded vermiculite, hollow glass microspheres and bentonites. Useful sheet materials also include those described in U.S. Patent No. 5,523,059, (Langer). In addition, examples of intumescent materials include those described in U.S. Patent Nos. 3,916,057 (Hatch et al.), 4,305,992 (Langer et al.), 4,385,135 (Langer et al.), 5,254,410 (Langer et al.), 4,865,818. (Merry et al.), 5,151,253 (Merry et al.), And 5,290,522 (Rogers et al.). Useful commercially available intumescent sheets and meshes include those sold under the trademark of INTERAMMR by Minnesota Mining & Manufacturing Co. of St. Paul, Minnesota. The mounting meshes typically have thicknesses of approximately 0.5 to 10 mm. Additionally, intumescent mounting materials include intumescent pastes, such as those described in US Patent Application No. 08 / 496,945 (Merry). Organic binders include those described above, such as natural rubber meshes, styrene-butadiene meshes, butadiene-acrylonitrile meshes, and polymer meshes and acrylate-methacrylate copolymers. 9 Inorganic fillers include expanded vermiculite, hollow glass microspheres and bentonite. Preferably, the inorganic fillers are expanded vermiculite. Ceramic fibers essentially free of particles useful for forming the non-intumescent inserts 28, include alumina-boria-silica fibers, alumina-silica fibers, phosphorus-alumina pentoxide fibers, zirconia-silica fibers, zirconia-alumina, and alumina fibers. Useful commercially available fibers include those under the trademarks FIBERMAX, available from Unifrax, SAFFIL, LD, available from ICI Chemicals & Polymers, ALCEN alumina fibers, available from Denka, and MAFTECH fibers, available from Mitsubishi.

The fibers are typically formed by blowing or centrifugation using methods known in the industry. Preferably, the fibers are formed by centrifuging a sol gel solution. The fibers are formed into a mesh by several known methods, including blowing the fibrous material onto a collection screen, as practiced in the non-woven fabric industry. A preferred intumescent material is a polycrystalline alumina fiber, available under the trademark of SAFFIL from ICI Chemicals and Polymers. The fiber is chemically resistant, and can be used in selected applications up to 1600 ° C. This is produced in a low density mesh form, which consists of predominantly two-dimensional random orientation fiber that results in a lamellar mesh. The mesh is essentially free of particles with a uniform fiber structure. The lamellar nature of the low density mesh makes it necessary to introduce means to prevent delamination during handling and assembly in the device for the control of contamination. That is to say, that the low density mesh of alumina fiber is preferably physically constrained or compressed during its handling and assembly. (As used herein, "particle-free" or "essentially particle-free" refers to a fiber mesh that is at least 95 percent particle-free, and preferably 99-percent particle-free). When compressed at an assembly density of approximately 0.10 and 0.60 grams per cubic centimeter, these materials have the unique ability to repeatedly experience a reduction in thickness while they are hot and return elastically substantially to their original thickness when cooled, exerting this mode continuously a substantial holding force for the catalytic monolith 20. Since the preferred fiber material for the non-intumescent inserts w is generally available in the density range of 0.020 to 0.060 grams per centimeter, and approximately one factor of 10 when used to mount the catalytic monolith 20. The meshes of non-intumescent insert material are generally compressed and maintained in a compressed state to facilitate handling of the material during assembly of the catalytic converter 10. The inserts 28 can be physically compressed in a variety ad of forms, including the use of union with resin, union by sewing, or perforation with needles, or packaging in vacuum. Bonding with resin is achieved by saturating the non-intumescent material with organic binders, which burn in the presence of the hot exhaust gas and allow the material of the insert 28 to expand during use. Due to the low density and voluminous nature of the fibers of - ceramics free of particles and the fact that they should normally be compressed by a factor of about 10 to obtain the desired mounting density, it has been found useful to sew or seam those materials with organic strands to form a compressed mesh that is very close of its final thickness in use. Sometimes it is useful to add a very thin sheet material as a support layer on both sides of the fiber meshes to prevent the seams from being cut or pulled through the fiber mesh. 9 The separation of the stitches is usually from 3 to 30 millimeters, so that the fibers are compressed uniformly throughout the entire area of the mesh. Organic materials burn when exposed to hot exhaust gas, and allow the compressed mesh to expand. The particle-free ceramic fiber can also be compressed by the seam. Ceramic fibers, by themselves are relatively fragile and not flexible enough to be sewn effectively. In order to effectively sew a ceramic fiber mesh, the mesh must first be coated with long flexible polymeric fibers, such as polypropylene fibers or polyester fibers, which are typically about 5-10 cm in length. A polymeric cambray, such as a nylon or non-woven fabric, is placed under the mesh. The mesh is compressed between a top plate and a bottom plate that has numerous holes in the plate. A pierced needle that has many small barbed needles, pushes the needles through the holes. When the needles penetrate the ceramic fiber mesh, the barbs push the polymeric fibers over the top of the mesh through the chambray, and the polymer fibers are attached to the chaplet to physically constrain the mesh. Organic fibers and chambray will burn when exposed to high temperatures of use, and allow ceramic fibers to expand. Fiber meshes can also be restricted by placing the fiber mesh in an air-tight bag, evacuating air from the bag, and sealing the bag. The atmospheric pressure retains the mesh in a compressed state until the bag is punctured or burned when the device for controlling the contamination is heated to the use temperature (more than 300 ° C). The non-intumescent inserts 28 provide two important functions. The inserts 28 have greater resistance to erosion when compared to the intumescent mesh 26. By placing inserts 28 along the lateral edges of the intumescent material which, in other circumstances are exposed to the hot exhaust gases, the inserts 28 serve to isolating the intumescent mesh 26 from the exhaust gas, and therefore preventing the erosion of the intumescent mesh 26. Although the use of materials to protect the edges is known, the prior art does not include an edge protection system that can expand and compress to accommodate the changing width of space between the monolith 20 and the case 12 under extreme temperature conditions or if the case deformation occurs. The protection mechanisms of the leading edges include the use of a stainless steel wire mesh around the edges of the intumescent mesh as described in U.S. Patent No. 5,008,086 (Merry), and ceramic fiber (i.e. glass, crystalline ceramic or glass ceramic), braided or similar to a braided rope or metal wire as described in U.S. Patent No. 4,156,333 (Cióse et al.). Edge protection can also be formed with compositions having glass particles as described in EP 639701A1 (Howorth et al.), EP 639702A1 (Howorth et al.) And EP 639700A1 (Stroom et al.). The inserts 28 also act as a seal between the monolith 20 and the case 12. The flexible and elastic nature of the preferred non-intumescent materials used for the inserts 28 ensure that the device for controlling contamination oscillates between high and low cycles temperature, the space between the monolith 20 and the case 12 is continuously sealed, and the exhaust gas is prevented from escaping the monolith. In this way, the efficiency of the device for the control of contamination is maintained, and the erosion of the intumescent mesh 26 by the blown exhaust gas is avoided. The objects and advantages of this invention are further illustrated by the following examples, but the materials and particular amounts thereof should not be unduly constituted as limiting of this invention. All parts and percentages are by weight unless otherwise stated.

Example 1 A layer of intumescent material (Mesh INTERAMMR Type 100, 3100 gsm (grams per square meter) available from Minnesota Mining and Manufacturing Co.) that measured 6.2 cm by 30 cm was cut as shown in Figure 5A. Strips of resin-bonded ceramic fiber mesh were cut (SAFFILMR chemically bonded mesh of 1200 gsm available from ICI Chemicals &Polymers Ltd.) to dimensions of 1.27 cm by 9 cm and were placed in the spaces cut in the intumescent mesh. The fiber mesh strips were held in place with a plastic tape to package to form a hybrid mounting mesh. The hybrid mounting mesh was wound around an oval ceramic monolith measuring 170 mm by 80 mm by 76 mm in length (available from Corning). A second monolith was wound in the same way with a hybrid mounting mesh identical to that described above. The rolled monoliths were mounted in a two-cavity stainless steel catalytic converter housing. It was determined that the mounting density was 0.7 g / cc (grams per cubic centimeter) for the intumescent mesh, and 0.27 g / cc for the fiber strips. The catalytic converter that contained the hybrid mounting meshes was then attached to a gasoline engine? (Ford Motor Co. 7.5 liter displacement V-8 petrol internal combustion engine) at 3000 rpm / 200 ft. lb. The catalytic converter was subjected to an inlet gas temperature of 900 ° C for a duration of 100 hours. After the test, the catalytic converter assembly was disassembled and inspected. No erosion was observed on the mounting material of the hybrid mounting mesh. Additionally, there was no discoloration along the wide portion of the housing over the fiber mesh strips. The presence of discoloration is indicative of the passage of hot exhaust gases between the mounting mesh and the metal housing. The absence of any discoloration indicates that the assembly was sealed sufficiently to prevent exhaust gases from flowing through the hybrid mesh mounting material.

Example 2 The mounting meshes tested in this example were prepared and tested as in Example 1, except that a commercially acceptable intumescent mesh material was used in place of the hybrid mounting mesh used in Example 1. After the test, Inspection of the mounting mesh revealed that the material of the mounting screen had been eroded by the engine exhaust gas. The maximum erosion distance, that is, the portion of the mounting mesh that was eroded, extended 23 mm towards the edge of the mounting mesh. A significant amount of discoloration was noted on the housing. A comparison of the operation of the tested mounting meshes showed significant improvements in the operation of the hybrid mounting mesh of Example 1 on the operation of the non-hybrid mounting mesh of Example 2. The hybrid mounting mesh withstood erosion when exposed to the exhaust gases, and provided a better seal between the monolith and the housing (as evidenced by the absence of discoloration of the housing in Example 1). Clearly, the operation of the hybrid mounting mesh (Example 1) is superior to the operation of the mounting mesh that does not use the fiber mesh inserts (Example 2). Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention.

It is noted that in relation to this date, the best method known by the applicant to bring to practice the aforementioned invention, is the conventional one for the manufacture of the objects to which it refers. Having described the invention as above, property is claimed as contained in the following:

Claims (21)

1. A pollution control device having a housing, a pollution control element positioned within the housing, and a mounting system placed between the contamination control element and the housing for positioning the element for the contamination. pollution control and to absorb mechanical and thermal shocks, the mounting system includes a mounting mesh having an intumescent layer 9 of the intumescent material, characterized in that at least a portion of the intumescent layer is replaced by an insert in the form of a layer of non-intumescent elastic, flexible, fibrous material.

The device for controlling pollution according to claim 1, characterized in that the insert is placed along at least a portion of at least one side edge of the mounting mesh.

3. The device for controlling pollution according to claim 1, characterized in that the intumescent material is a sheet material.

4. The device for controlling pollution according to claim 1, characterized in that the intumescent material is a paste.

The device for controlling pollution according to claim 1, characterized in that the non-intumescent elastic inserts are formed of ceramic fibers essentially free of particles.

The device for controlling the contamination according to claim 1, characterized in that the element for the control of the contamination is a monolithic ceramic body.

The device for controlling pollution according to claim 1, characterized in that the element for controlling the contamination is a metallic monolithic body.

8. The device for controlling pollution according to claim 5, characterized in that the ceramic fiber insert essentially free of particles is physically compressed.

9. The device for controlling pollution according to claim 8, characterized in that the ceramic fiber insert essentially free of particles is bonded with resin.

The device for controlling pollution according to claim 8, characterized in that the ceramic fiber insert essentially free of particles is joined by stitching.

The device for controlling pollution according to claim 8, characterized in that the ceramic fiber insert essentially free of particles is sewn with needles. 9

12. The device for controlling pollution according to claim 5, characterized in that the fiber-free ceramic particles essentially comprise alumina-boria-silica fibers, alumina-silica fibers, alumina-phosphorus pentoxide fibers, Zirconia-silica, alumina and zirconia-alumina fibers.

The device for controlling pollution according to claim 5, characterized in that the ceramic fiber essentially free of particles is derived from a sol-gel process.

The device for controlling pollution according to claim 2, characterized in that the non-intumescent insert is secured to the side edge of the mounting mesh using adhesive tape.

15. The device for controlling pollution according to claim 2, characterized in that the non-intumescent insert extends along the entire lateral edge of the mounting mesh.

16. The device for controlling pollution according to claim 1, characterized in that the non-intumescent insert is expanded to fill a space or gap between the metal housing and the element for control of contamination.

17. The device for controlling pollution according to claim 1, characterized in that the elasticity of the non-intumescent insert is greater than the elasticity of the mounting mesh.

18. The device for controlling contamination according to claim 2, characterized in that the non-intumescent insert is bonded with resin in an uncompressed state before being exposed to hot exhaust gases, and where exposure to gases of hot exhaust, burns the binder to allow the expansion of the plastic material.

19. A mounting system, characterized in that it comprises: a layer of intumescent sheet material, and at least one insert that is in the form of a layer of elastic, flexible, fibrous non-intumescent material and replacing a portion of the intumescent layer.

20. The mounting grid according to claim 19, characterized in that the insert is positioned along at least a portion of at least one side edge of the mounting mesh.

21. A mounting mesh for securing a first and second element for the control of contamination within a housing of an energy control device, the mounting mesh is characterized in that it comprises: a first longitudinal strip of intumescent material, a second longitudinal strip of the intumescent material, a metal band secured along the side edges of the first and second strips of intumescent material, the metal band separates the intumescent strips, and an insert in the form of a layer of non-intumescent material elastic, flexible, fibrous and replacing a portion of the intumescent layer, the insert is positioned adjacent to the metal band and at least a portion of the lateral edges of the first and second intumescent strips.