Abstract:
A combination exhaust manifold and catalytic converter wherein the catalytic converter is in the form of a removable and replaceable cartridge mounted within an opening of an exhaust manifold. This cartridge is supported within the opening of the exhaust manifold by sealing rings and retained within the opening by a removable fastener element.

Description:
FIELD OF THE INVENTION 
     The present invention relates to exhaust systems for combustion engines and, more particularly, to the exhaust manifold and catalytic converter of such systems. In accordance with this invention, the catalytic converter is in the form of a removable and replaceable cartridge mounted within an opening of the exhaust manifold. 
     BACKGROUND OF THE INVENTION 
     Exhaust systems for a combustion engine generally include a manifold connected to the combustion engine at one end and bolted to an exhaust pipe at the other end. The exhaust pipe extends a distance from the manifold and generally has a catalytic converter system bolted thereto. These catalytic converter systems generally include a ceramic substrate having a catalyst coated thereon and a metal housing surrounding the substrate. A compressible support mat is usually placed between the ceramic substrate and the metal housing. This support mat functions to accommodate differentials in expansion between the ceramic substrate and the surrounding metal housing, as well as to protect the relatively fragile ceramic substrate from vibration and jarring movement of the engine and exhaust system. 
     Relatively recently, catalytic converters have been mounted very close to the combustion engine, and in at least one patent disclosure, that of U.S. Pat. No. 6,605,259, within an end opening of the exhaust manifold. When so mounted though, and as disclosed in this patent, the exhaust manifold has had to have end cones formed at the entrance and exit ends of the catalytic converter which is necessarily an expensive casting and assembly practice. 
     It has been an objective of this invention to provide a catalytic converter which is so mounted within an exhaust manifold that there is no need for the formation of end cones. 
     Another objective of this invention has been to construct the catalytic converter in such a fashion and to mount it in the exhaust manifold such that it may be easily and conveniently replaced if necessary after protracted use or if it inadvertently fails during use. To that end, the catalytic converter of this application comprises a self-contained cartridge which is removably and replaceably supported within the exhaust manifold of a combustion engine. 
     SUMMARY OF THE INVENTION 
     The present invention includes an exhaust manifold mounted catalytic converter cartridge which is positioned within an opening near the exhaust end of the exhaust manifold. The catalytic converter cartridge comprises a catalyst coated ceramic or other conventional material substrate surrounded and retained within a sheet metal shell by a supporting mat. The sheet metal shell is, in turn, supported within the opening in the exhaust manifold by wire mesh seals located at opposite ends of the cartridge. This replaceable cartridge is retained in the opening by a removable fastener element, preferably in the form of an expansible retainer ring located in a groove of the manifold opening and engageable with one of the wire mesh seals at one end of the cartridge and operative to force the complete cartridge against an internal abutment of the manifold at the opposite end of the cartridge. 
     The primary advantage of this combination exhaust manifold and catalytic converter cartridge combination is that it substantially reduces the cost which has heretofore been characteristic of catalytic converters when placed in the exhaust system of a combustion engine and, additionally, it facilitates replacement of the catalytic converter in the event of a functional breakdown of that portion of the exhaust system. 
    
    
     
       These and other objects and advantages of this invention will be more readily apparent from the following description of the drawings, in which: 
         FIG. 1  is a perspective view of an exhaust manifold and catalytic converter cartridge characteristic of the invention of this application; 
         FIG. 2  is an exploded perspective view of the catalytic converter and the exhaust manifold of  FIG. 1 ; 
         FIG. 3  is a cross sectional view through the catalytic converter and the assembled exhaust manifold and catalytic converter of  FIG. 1 ; 
         FIG. 4  is a cross sectional view of a wire mesh seal utilized in the catalytic converter cartridge of  FIG. 1 ; and 
         FIG. 5  is a perspective view of a retainer ring utilized in connection with the catalytic converter and manifold of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference first to  FIG. 1 , there is illustrated an exhaust manifold  10  and catalytic converter cartridge  12  for use in combination with that exhaust manifold. The exhaust manifold here illustrated is for use with an internal combustion engine and to that end, has inlet ports  14  adapted to be placed in gaseous fluid communication with the individual cylinders of a combustion engine (not shown) with which the manifold is intended to be used. Each of these inlet ports  14  is connected through conventional duct work  16  to a common inlet duct  18  which in turn opens into the catalytic converter receiving section  20  (hereinafter referred to as the can section) of the exhaust manifold. The exhaust manifold  10  herein described is a water-cooled, dual-walled manifold intended for use in connection with marine engines wherein water is cycled through the manifold so as to control the outer manifold temperature, but the invention of this application is equally applicable to single-walled manifolds used in connection with marine or any other application combustion engine. 
     In practice, the exhaust manifold is conventionally made from aluminum, but for purposes of this invention, may be made from any material from which manifolds are conventionally manufactured. 
     With reference now to  FIGS. 2 and 3 , it will be seen that the catalytic converter cartridge  12  comprises a central cylindrical substrate  22  encased within a sheet metal shell  24  and retained within that shell by a compressible mat  26 . The sheet metal shell is, in turn, retained within the central opening  28  of the can section  20  of the manifold by a pair of annular wire mesh seals  32 ,  34 . The complete cartridge is retained within the opening  28  of the can section of the manifold by a snap-in-style retainer ring  36  located within an internal groove  38  formed on the inside wall of the opening  28  of the exhaust manifold. 
     The central generally cylindrical substrate  22  may be of circular or oval cross section or any other cross sectional shape, such as hexagonal or poly-sided. It may comprise any material designed for use in a gasoline or diesel engine environment and having the following characteristics: (capable of operating at temperatures up to about 800° C.), (2) capable of withstanding exposure to hydrocarbons, nitrogen oxides, carbon monoxide, particulate matter (e.g., soot and the like), carbon dioxide, and/or sulfur; and (3) having sufficient surface area and structural integrity to support a catalyst. Some possible materials include cordierite, silicon carbide, metal, metal oxides (e.g., alumina and the like), glasses, and the like, and mixtures comprising at least one of the foregoing materials. Preferably, substrate  22  comprises a ceramic material. 
     Disposed substantially throughout the substrate  22  is a catalyst capable of reducing the concentration of at least one component in the gas. The catalyst may be wash coated, imbibed, impregnated, physisorbed, chemisorbed, precipitated, or otherwise applied to the substrate. Possible catalyst materials include metals, such as platinum, palladium, rhodium, iridium, osmium, ruthenium, tantalum, zirconium, yttrium, cerium, nickel, manganese, copper, and the like, as well as oxides, alloys and combinations comprising at least one of the foregoing catalysts, and other catalysts. 
     The mat  26  a may be an intumescent material mat (e.g., a material that comprises vermiculite component, i.e., a component that expands upon the application of heat), or a non-intumescent material, or a combination thereof. These materials may comprise ceramic materials (e.g., ceramic fibers) and other materials such as organic and inorganic binders and the like, or combinations comprising at least one of the foregoing materials. Non-intumescent materials include materials such as those sold under the trademarks “NEXTEL” and “INTERAM 1101HT” by the “3M” Company, Minneapolis, Minn., or those sold under the trademark “FIBERFRAX” and “CC-MAX” by the Unifrax Co., Niagara Falls, N.Y., and the like. Intumescent materials include materials sold under the trademark “INTERAM” by the “3M” Company, Minneapolis, Minn., as well as those intumescents which are also sold under the aforementioned “FIBERFRAX”™, well as combinations thereof and others, including mats manufactured and sold by Saffil Ltd. and Ibiden Co. Ltd. The mat  26  is most often a fibrous material which, in addition to being able to withstand the temperatures of the engine exhaust, is sufficiently compressible and resilient as to firmly hold the varying dimension substrate within the sheet metal sleeve or shell  24  without breakage when subjected to engine vibration and jarring movement of the manifold. 
     The sheet metal shell or sleeve  24  within which the substrate  22  and mat  26  are contained is tubular in configuration and has inwardly turned flanges  40 ,  42  at its opposite ends. The choice of material for the shell depends upon the type of exhaust gas, the maximum temperature reached by the substrate, the maximum temperature of the exhaust gas stream, and the like. Suitable materials for the housing may comprise any material that is capable of resisting temperature, and corrosion. For example, ferrous materials can be employed such as ferritic stainless steels, as well as various metal alloys, such as alloys of nickel, chromium and/or iron. 
     The catalytic converter cartridges  12  may be assembled by one or more techniques, and, likewise, the mat material/substrate subassembly may be disposed within the housing one or more methods. For example, the mat material/substrate subassembly may be inserted into the shell  24  using a stuffing cone. The stuffing cone is a device that compresses the mat concentrically about the substrate. The stuffing cone then stuffs the compressed mat/substrate subassembly into the housing, such that an annular gap preferably forms between the substrate and the interior surface of the shell as the mat material becomes compressed about the substrate. 
     In an alternative method, the so-called “tourniquet” method of forming the catalytic converter comprises wrapping the shell (e.g., in the form of a sheet) around the mat material/substrate subassembly. The adjoining edges of the shell are welded together while the assembly is squeezed at rated pressures calculated to optimize the retention material density. Although this method has the disadvantages of increased cost due to the number of components that have to be processed and the added cost of welding wires and gases, it often is characterized as having improved retention material density control. 
     The wire mesh seals  32 ,  34  engage the flanges  40 ,  42 , as well as the outside peripheral surface  44  of the shell  24  to retain the catalytic converter cartridge within the opening  28  of the exhaust manifold. With reference to  FIG. 4 , there is illustrated the details of the wire mesh seals  32 ,  34 , only one of which is illustrated in  FIG. 4  since the two seals are identical. These seals are made from a fine wire mesh which is able to withstand the heat of the exhaust gases from the engine with which the manifold and catalytic converter are utilized and still be sufficiently compressible so as to fixedly and sealingly hold the catalytic converter within the manifold. Each seal comprises an annular or oval or other shape section  46  which conforms to the cross sectional shape of the substrate and sheet metal shell. It surrounds the periphery of the metal shell  24  and has an inwardly turned flange section  48  which engages the end of the shell. 
     As may be seen most clearly in  FIG. 3 , the completely assembled cartridge is retained within the opening  28  of the exhaust manifold by the snap-fit retainer ring (see  FIG. 5 ) which is received within the groove  38  in the exhaust manifold. As illustrated in  FIG. 5 , the snap-in retainer ring is a conventional multiple revolution retainer ring having spaced ends  37 ,  37 ′ which permit contraction of the ring for placement and insertion into the annular groove  38 . The retainer ring could as well be a single revolution ring or any other shaped snap-in ring. 
     In order to assemble the catalytic converter cartridge within the central opening  28  in the manifold can  20 , the cartridge, as illustrated in  FIG. 1 , is inserted through the end opening  50  of the can section  20  of the manifold. The cartridge having the seals  32 ,  34  applied thereto is inserted or pushed inwardly into that opening (preferably using a stuffing cone) until the flange  48  of the wire mesh seal  32  engages an abutment surface  52  of the manifold. The snap-in retainer ring  36  is then inserted into the groove  38  while compressed and allowed to expand into the groove  38  of the exhaust manifold. When so expanded, the inside surface of the retainer ring engages the flange  48  of the wire mesh seal  30  so as to lock the cartridge  12  within the can section  20  of the manifold  10 . 
     In the event that the substrate  22  of the catalytic converter cartridge  12  should ever become clogged or broken or otherwise fail for any reason, the complete cartridge may be removed and replaced by a new cartridge  12  by simply compressing the snap-in retainer ring  36  and sliding the failed cartridge out of the opening. Thereafter, the new cartridge  12 , again preferably using a stuffing cone, may be inserted and the retainer ring replaced in the groove so as to hold the new cartridge having new seals  32 ,  34  applied thereto within the can section of the manifold. 
     With reference now to  FIG. 5 , there is illustrated a conventional snap-in-style of retainer ring. Of course, other fastener elements could be used for the same purpose of locking the replaceable catalytic converter cartridge within the can section of the manifold. For example, a threaded ring could be used in lieu of a snap-in-style retainer ring or any other conventional style of fastener element could be utilized to secure the catalytic converter cartridge within the can section of the manifold. 
     While we have described only a single embodiment of our invention, persons skilled in this art will readily appreciate changes and modifications which may be made without departing from the spirit of our invention.