Abstract:
An end cone for an exhaust emission control device is provided. The end cone comprises an outer shell and an end cone insulator. The outer shell has an inner surface. The end cone insulator comprises insulation and binder defining a passage therethrough. The end cone insulator has a first surface being disposed adjacent to the inner surface, and a second surface, at least a portion of which is exposed to the passage.

Description:
BACKGROUND  
         [0001]    This disclosure relates to exhaust emission control devices. More particularly, this disclosure relates to end cones for exhaust emission control devices.  
           [0002]    The removal of emissions, such as hydrocarbon, carbon monoxide, nitrogen oxide, particulate matter, and the like, from the exhaust gases of internal combustion engines is required for cleaner operating vehicles. One focus area for such exhaust emission reduction has been in the area of post combustion treatment. Namely, post combustion treatment includes the placement of one or more exhaust emission control devices in the exhaust down stream of the internal combustion engine. Such exhaust emission control devices include catalytic converters, catalytic absorbers, diesel particulate traps, non-thermal plasma conversion devices, and the like.  
           [0003]    Many exhaust emission control devices often include fragile structures prone to crushing and damage in the exhaust environment. For example, exhaust emission control devices have used a substrate or monolith, commonly made of fireproof ceramic (e.g., cordierite, carbon, and the like). The substrate includes a cellular structure to provide a high surface area for exposure to the exhaust gas.  
           [0004]    The substrate is often retained in the exhaust pipe housing by means of a retention material or mat. The retention material is adapted to retain the substrate in housing and to seal the gap between the substrate and the housing to force the exhaust gas through the cellular structure of the substrate.  
         SUMMARY  
         [0005]    An end cone for an exhaust emission control device is provided. The end cone comprises an outer shell and an end cone insulator. The outer shell has an inner surface. The end cone insulator comprises insulation and binder defining a passage therethrough. The end cone insulator has a first surface being disposed adjacent to the inner surface, and a second surface, at least a portion of which is exposed to the passage.  
           [0006]    A method of manufacturing an end cone is provided. The method comprises forming an outer shell, forming an end cone insulator, and disposing the end cone insulator in the outer shell. The outer shell has an inside surface. The end cone insulator comprises binder and insulation. The end cone insulator has an inboard end, an outboard end, a first surface, and a second surface. The end cone insulator is disposed in the outer shell such that the inside surface and the first surface are adjacent, and such that at least a portion of the second surface is exposed.  
           [0007]    An exhaust emission control device is provided. The device comprises a substrate, a housing, a retention material, a pair of outer shells, and a pair of insulators. The housing has an inlet end and an outlet end. The retention material supports the substrate in the housing between the inlet end and the outlet end. One of the outer shells is disposed on the inlet end, and a second one of the outer shells is disposed on the outlet end. The insulators are comprised of insulation and binder. The insulators have a first surface disposed adjacent to an inner surface of the outer shell. Each of the insulators is connected at least at an outboard end to the outer shells, and each of the insulators is supported at an inboard end by the substrate and the retention material.  
           [0008]    A method of manufacturing an exhaust emission control device is provided. The method comprises forming insulators from binder and insulation, and supporting a substrate in a housing with a retention material. The insulators have an inboard end, an outboard end, a first surface, and a second surface opposite the first surface. The housing has an inlet end and an outlet end. The method further comprises placing a first one of the insulators at the inlet end such that its inboard end is supported by the substrate and the retention material, and placing a second one of the insulators at the outlet end such that its inboard end is supported by the substrate and the retention material.  
           [0009]    The above-described and other features are appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    Referring now to the Figures, where like elements are numbered alike:  
         [0011]    [0011]FIG. 1 is a partially cut-away perspective view of an exhaust emission control device;  
         [0012]    [0012]FIG. 2 is a cross sectional view of the exhaust emission control device of FIG. 1, taken along lines  2 - 2 ;  
         [0013]    [0013]FIG. 3 is an exploded perspective view of an exhaust emission control device having end cones;  
         [0014]    [0014]FIG. 4 is a cross-sectional view of the device of FIG. 3 taken in a direction perpendicular to the longitudinal axis of the device;  
         [0015]    [0015]FIG. 5 is a sectional view of the device of FIG. 3 illustrating an exemplary embodiment of an end cone insulator;  
         [0016]    [0016]FIG. 6 is a sectional view of the device of FIG. 3 illustrating an alternate exemplary embodiment of an end cone insulator;  
         [0017]    [0017]FIG. 7 is a sectional view of the device of FIG. 3 illustrating another exemplary embodiment of an end cone insulator;  
         [0018]    [0018]FIG. 8 is a sectional view of the device of FIG. 3 also illustrating an exemplary embodiment of an end cone insulator; and  
         [0019]    [0019]FIG. 9 is a sectional view of an alternate embodiment of a housing using the end cone insulator of FIG. 8. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]    Referring now to FIGS.  1 - 3 , an exhaust emission control device  10  is illustrated. Exhaust emission control device  10  includes an outer housing  12 , a substrate  14 , and a retention material  16 . Disposed at both ends of the device  10 , i.e., an inlet end  24  and at an outlet end  26 , are end-cones  22  connectable in fluid communication with an exhaust gas stream of an internal combustion engine. By way of example, device  10  is a catalytic converter, a catalytic absorber, a diesel particulate trap, a non-thermal plasma conversion device, and the like. Accordingly, by way of example, substrate  14  is a catalytic converting substrate, a catalytic absorbing substrate, a diesel particulate trapping substrate, a non-thermal plasma converting substrate, and the like.  
         [0021]    Retention material  16 , which is concentrically disposed around the substrate  14 , comprises either be an intumescent material, e.g., one which comprises ceramic materials, and other materials such as organic binders and the like, or combinations comprising at least one of the foregoing materials, and a vermiculite component that expands with heating to maintain firm uniform compression, or non-uniform compression, if desired; or a non-intumescent material, e.g., one that does not contain vermiculite; as well as materials which include a combination of both intumescent and non-intumescent materials. Non-intumescent materials include materials such as 900HT, 1100HT, and those sold under the trademarks “NEXTEL” and “SAFFIL” 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., such as INTERAM 100, as well as those intumescents which are also sold under the aforementioned “FIBERFRAX” trademark by the Unifrax Co., Niagara Falls, N.Y. as well as combinations comprising at least one of the foregoing materials, and others.  
         [0022]    In use, exhaust emission control device  10  is subjected to a large range of temperatures and vibrations. Accordingly, the retention pressure placed on substrate  14  by retention material  16  is sufficient to successfully hold the substrate and insulate it from shock and vibration. The retention material  16  should further form a barrier between the substrate and the interior of the housing  12  by substantially filling the space there between, thereby ensuring that the exhaust gas passes through cells  18  of the substrate.  
         [0023]    For example, when the exhaust emission control device  10  is placed in the exhaust stream after the internal combustion engine of a vehicle (not shown), exhaust gas passes through cells  18  of substrate  14 . The substrate  14  itself and/or active materials thereon reduce, convert, and/or eliminate one or more emissions from the exhaust stream.  
         [0024]    Substrate  14  comprises any material designed for use in a spark ignition or diesel engine environment and having the following characteristics: (1) capable of operating at temperatures up to about 1,000° C.; (2) capable of withstanding exposure to hydrocarbons, nitrogen oxides, carbon monoxide, carbon dioxide, and/or sulfur; and if a catalyst is employed, (3) having sufficient surface area and structural integrity to support the desired emission acting components (e.g., catalyst materials). Some possible materials for substrate  14  include, but are not limited to, cordierite, silicon carbide, metallic foils, alumina sponges, porous glasses, and the like, and mixtures comprising at least one of the foregoing materials. Some ceramic materials include “Honey Ceram”, commercially available from NGK-Locke, Inc, Southfield, Mich., and “Celcor”, commercially available from Corning, Inc., Corning, N.Y.  
         [0025]    The size and geometry of substrate  14  are chosen to optimize surface area of cells  18  in the given design parameters of exhaust emission control device  10 . Typically, substrate  14  has a honeycomb geometry. Cells  18  are contemplated as having any polygonal or rounded shape, with substantially square, triangular, pentagonal, hexagonal, heptagonal, or octagonal, or similar geometries, as well as combinations comprising at least one of these geometries, preferred, due to ease of manufacturing and increased surface area.  
         [0026]    Depending upon the type of the emission control device  10 , disposed on and/or throughout the substrate  14  may be a catalyst for converting one or more exhaust gasses (e.g., hydrocarbons, carbon monoxide, sulfur, nitrogen oxides, and the like) to acceptable emissions levels. The catalyst comprises one or more catalyst materials that are wash coated, imbibed, impregnated, physisorbed, chemisorbed, precipitated, or otherwise applied to substrate  14 . Possible catalyst materials include metals, such as platinum, palladium, rhodium, iridium, osmium, ruthenium, tantalum, zirconium, yttrium, cerium, nickel, copper, and the like, as well as oxides, alloys, and combinations comprising at least one of the foregoing catalyst materials, and other catalysts.  
         [0027]    The choice of material for housing  12  and/or end cones  22  depends upon the type of exhaust gas, the maximum temperature reached by device  10 , the maximum temperature of the exhaust gas stream, and the like. Suitable materials include any material that is capable of resisting under-car salt, temperature, and corrosion. Typically, ferrous materials are employed such as ferritic stainless steels. Ferritic stainless steels include stainless steels such as, e.g., the 400—Series such as SS-409, SS-439, and SS-441, with grade SS-409 generally preferred.  
         [0028]    As illustrated in FIG. 4, each end cone  22  includes an inner shell  28 , an outer shell  30 , and a layer of insulation  32 . Inner shell  28  and outer shell  30  are joined to each other remote from housing  12 . Namely, inner shell  28  and outer shell  30  are joined at one end, and are configured to diverge from each other as the distance from the joined end increases, thereby forming a gap  36  at the opposing or second end. Thus, shells  28  and  30  define an open area  34  therebetween, and gap  36  for receiving an end of housing  12 .  
         [0029]    Outer shell  30  has an inner surface connected to an outer surface  38  of housing  12  such that inner shell  28  is between substrate  14  and the housing. In this manner, inner shell  28  is configured to direct the exhaust gas through substrate  14 . Accordingly, the second end of inner shell  28  is preferably positioned proximate substrate  14 . Inner shell  28  therefore also directs the exhaust gas away from retention material  16  and insulation  32  to protect the retention material and the insulation from erosion due to exposure to the exhaust gas.  
         [0030]    Preferably, the second end of inner shell  28  extends into retention material  16 . The distance of the extension is preferably sufficient to direct the exhaust gas into substrate  14 . For example, an extension of less than or equal about 4 millimeters are employed, with an extension of greater than or equal to about 2 mm preferred. In the region where the inner shell  28  extends into the retention material  16 , the compression of retention material  16  is increased, which makes retention material  16  less porous at the inlet of substrate  14  further aiding in the direction of the exhaust gas into the substrate. Disposed between the inner shell  28  and the outer shell  30  is a layer of insulation  32 . The insulation  32  comprises a plurality of relief area or notches  31  to allow the insulation to conform to the curve of shells  28  and  30 . The formation of notches  31  adds expense and time to the manufacture of end cones  22 . Insulation  32  reduces heat loss from the exhaust gas and reduces radiated sound from device  10 . For example, in the instance where substrate  14  comprises a catalyst, insulation  32  ensures that the catalyst reaches its “light-off” or activated temperature quickly during cold start-ups of the engine. Insulation  32  also aids in reducing the temperature of outer shell  30 , which is useful for thermal management of the vehicle.  
         [0031]    However, inner shell  28  adds to the thermal mass of end cone  22 , which frustrates the effects of insulation  32  and leads to an increase in the end cone&#39;s conduction of heat to outer shell  30 . Further, when device  10  reaches its operating temperature inner shell  28  is exposed a higher temperature than is outer shell  30 . Thus, in instances where inner and outer shells  28  and  30  have a similar coefficient of thermal expansion, the inner shell expands more than the outer shell, which decreases open area  36  and compresses insulation  32 . Compression of insulation  32  reduces its insulatory effects, which further increases the end cone&#39;s conduction of heat to outer shell  30 .  
         [0032]    The formation of inner shell  28  also requires costly and time-consuming progressive die or die set operations. Thus, inner shell  28  increases the cost of end cone  22 , decreases the end cone&#39;s ability to maintain a desired temperature of outer shell  30  and/or substrate  14 , and increases damage to the substrate in the areas of increased compression of retention material  16 .  
         [0033]    Referring now to FIGS.  5 - 8 , exemplary embodiments of end cone insulators are illustrated. An exemplary embodiment of an end cone insulator  40  is illustrated in FIG. 5. End cone  22  includes an outer shell  30  and end cone insulator  40 . End cone insulator  40  comprises a layer of insulation  32  impregnated, dispersed, and/or mixed with a binder  33 . Insulation  32 , impregnated with binder  33 , provides insulator  40  with a semi-rigid configuration.  
         [0034]    More specifically, end cone insulator  40  replaces the inner shell  28 . Here, end cone insulator  40  has a shape that conforms to the interior shape of the outer shell  30 . Binder, or similar material,  33  enables molding or otherwise forming of insulation  32  into the desired shape and provides the insulator with the desired structural integrity.  
         [0035]    Preferably, end cone insulator  40  extends into retention material  16 . The distance of the extension is preferably sufficient to direct the exhaust gas into substrate  14 . For example, an extension of less than or equal about 4 millimeters are employed, with an extension of greater than or equal to about 2 mm preferred. In the region where end cone insulator  40  extends into the retention material  16 , the compression of the retention material is increased, which makes the retention material less porous at the inlet of substrate  14  further aiding in the direction of the exhaust gas into the substrate.  
         [0036]    Accordingly, insulator  40  is configured to reduce heat loss from the exhaust gas, to reduce radiated sound from device  10 , to direct the exhaust gas through substrate  14 , and to direct the exhaust gas away from retention material  16 .  
         [0037]    Insulation  32  and binder  33  are selected from materials capable of withstanding the exhaust gas environment. For example, in one embodiment, insulation  32  is a vermiculite or ceramic fiber based material similar to that of retention material  16 , while binder  33  is an inorganic binding material. Of course, other insulations and binders that provide end cone insulator  40  with the desired structural stability and are capable of withstanding the exhaust environment are contemplated.  
         [0038]    During assembly, end cone insulator  40  is either preformed and placed in outer shell  30  or is formed directly in outer shell  30 . Outer shell  30  with end cone insulator  40  is then connected to outer surface  38  of housing  12 . Here, an inboard end  42  of end cone insulator  40  is supported by substrate  14  and retention material  16 , while an outboard end  44  of the end cone insulator is connected to outer shell  30 . Outboard end  44  is connected to, secured to, and/or held against (hereinafter “connected”) outer shell  30  by, for example, an adhesive, a binder, by mechanical means, by radial forces (e.g., due to the size and geometry of the insulator  40  in relation to the outer shell  30 ), by the cooperation of the shape of the shell/insulator, and the like, as well as combinations comprising at least one of the foregoing.  
         [0039]    End cone insulator  40  provides many benefits through the elimination of the inner shell. For example, eliminating the inner shell removes the costly and time-consuming operations necessary to form it. Eliminating the inner shell also reduces the thermal mass of end cone  22 , and thus, decreases the end cone&#39;s conduction of heat to outer shell  30 . Further, eliminating the inner shell eliminates the compression of the insulation  32  from differences in thermal expansion of the outer and inner shells. Thus, end cone insulator  40  further reduces conduction of heat to outer shell  30 , which increases the performance of device  10 .  
         [0040]    Referring now to FIG. 6, an alternate exemplary embodiment of an end cone insulator  40  is illustrated. Here, end cone  22  includes outer shell  30  and end cone insulator  40 . In this embodiment, end cone insulator  40  includes not only binder  33  disposed in insulation  32 , but also includes a mesh or screen  35 .  
         [0041]    Mesh  35  disposed on the surface  39  of insulator  40  exposed to the exhaust gas (i.e., the surface of insulator  40  that is opposite the side of the insulator in contact with outer shell  30 ). The mesh or screen  35  prevents eroded insulator  40  particles from breaking loose, passing into, and/or fouling cells  18  of the substrate  14 . That is, as the density of cells  18  of substrate  14  increases (see FIG. 1), the cross sectional size of the cells decreases. This decrease in size increases the likelihood of blockage or fouling of cells  18  by particulate matter, which reduces the useful life of device  10 . The mesh  35  inhibits particulate matter from insulator  40  from entering substrate  14 . Since the inlet  24  is upstream of cells  18 , the inclusion of end cone insulator  40  having mesh  35  at least at the inlet is desired.  
         [0042]    In an alternate embodiment, at outlet  26  (e.g. downstream of cells  18 ) does not include mesh  35 . In this embodiment, the use of the mesh  35  at outlet  35  is optional since it is not necessary to prevent fouling of cells  18 . Thus, in this embodiment device  10  has end cone insulator  40  at inlet  24  with mesh  35 , but has an end cone insulator at outlet  26  without the mesh.  
         [0043]    Mesh  35  includes one or several layers of woven or non-woven fibers, strands, or the like, (e.g., screen(s), blanket(s), and the like) with a sufficient amount of layers to attain the desired particulate retention preferred. Mesh  35  comprises a material capable of withstanding the exhaust gas environment. Some possible materials include those employed for the housing  12 , with stainless steel typically preferred.  
         [0044]    The use of mesh  35  to add structure and rigidity to insulator  40  is also contemplated. In this embodiment, mesh  35  comprises a sufficient amount of layers or layer thickness to impart the desired structural integrity to insulator  40 .  
         [0045]    Referring now to FIG. 7, another alternate exemplary embodiment of an end cone insulator  40  is illustrated. Again, end cone  22  includes outer shell  30  and end cone insulator  40 . In this embodiment, end cone insulator  40  includes insulation  32  and binder  33 , and further includes an inner core or tube  37 . Core  37  and outer shell  30  are joined remote from housing  12 . As shown, core  37  terminates before substrate  14 . Thus, core  37  does not have the thermal mass described above with respect to the inner shell  28 . (see FIG. 4) Core  37  is joined to outer shell  30  by, for example, welding, dimpling, bonding, and the like.  
         [0046]    Here, inboard end  42  of end cone insulator  40  is supported by substrate  14  and retention material  16 , while outboard end  44  of the end cone insulator  40  is disposed between at least a portion of core  37  and outer shell  30 . In this configuration, thus core  37  supplements and/or eliminates the joining (mechanical, binder, and the like) of outer shell  30  and end cone insulator  40 . Preferably, the core  37  extends a sufficient distance from the inlet  24  to the inlet end of the retention material  16  to provide retention of the insulator, while not undesirably increasing the thermal mass of insulator  40 .  
         [0047]    Referring now to FIG. 8, another alternate exemplary embodiment of an end cone insulator  40  is illustrated. Again, end cone  22  includes outer shell  30  and end cone insulator  40 . In this embodiment, end cone insulator  40  includes insulation  32 , binder  33 , screen  35 , and inner core or tube  37 .  
         [0048]    It should be recognized that housing  12  is provided above with respect to FIGS.  5 - 8  by way of example only as including identical end cones insulators  40  at inlet end  24  and outlet end  26 . Of course, ends cone insulators having different features and construction at inlet end  24  than at outlet end  26  are contemplated.  
         [0049]    Housing  12  is also discussed above with respect to FIGS.  5 - 8  is described as a unitary housing, requiring the attachment of separate end cones  22 . However, the configuration of the housing is often dependant on the method by which substrate  14  wrapped with retention material  16  is inserted into the housing. For example, in the embodiments discussed above, substrate  14  wrapped with retention material  16  is inserted into housing  12  through one of the open ends of the housing before end cone  22  is connected to the housing. This method is commonly referred to as the “stuffing method”. Of course, other housing designs (e.g., sheet of material, two halves of material, and the like) and other methods (e.g., clam shell, wrapping, and the like) exist, and are contemplated, for the housing and for inserting substrate  14  wrapped with retention material  16  into the housing, respectively.  
         [0050]    Other methods include other stuffing methods, the clamshell method, the tourniquet method, and the like. For example, another version of the “stuffing method” is referred to as the “stuffing and resizing method”. Here, substrate  14  wrapped with retention material  16  is inserted into housing  12  through one of the open ends of the housing. Next, one or more portions of housing  12  is resized or compressed. Furthermore, one or both of the ends of housing  12  is resized to provide outer shell  30 , e.g., via spin-forming and the like. Another commonly used method is referred to as the “clamshell method”. Here, substrate  14  wrapped with retention material  16  is placed between two longitudinal halves or clamshells of housing  12 , which includes outer shell  30  integrated thereon. Here, the two halves of housing  12  are closed around the assembly and welded together. Similarly, with the tourniquet method, the substrate  14 , wrapped with retention material  16 , is inserted into housing  12 , which is open on one longitudinal edge and which includes outer shell  30  integrated thereon. Here, housing  12  is closed around the assembly and the open longitudinal edge is then welded closed. Referring now to FIG. 9, and as provided above, it is known to provide outer shell  30  formed as part of housing  12 .  
         [0051]    In this example, housing  12  is shown having an end cone insulator  40 , which includes both screen  35  and inner core or tube  37  as described above.  
         [0052]    During assembly with the “stuffing and resizing method” for example, substrate  14 , wrapped with retention material  16 , is inserted into housing  12  through one of the open ends of the housing. End cone insulators  40  are disposed in operable communication with substrate  14  such that inboard ends  42  of the end cone insulators are supported by the substrate and retention material  16 . End cone insulators  40  are disposed around substrate  14  either before or after insertion into housing  12 . The ends of housing  12  are then resized around end cone insulators  40  to provide outer shell  30 . For example, housing  12  is resized by spin forming, ram forming, magnetic impulse, and the like. Core  37  is optionally secured to outer shell  30  by, for example, welding, bonding, dimpling, compression of the outer shell on the core, and the like.  
         [0053]    During assembly with the “clamshell method” for example, substrate  14  is wrapped with retention material  16 . End cone insulators  40  are disposed in operable communication with substrate  14  (e.g., around at least an end of substrate  14 ) such that inboard ends  42  of the end cone insulators are supported by the substrate and retention material  16 . End cone insulators  40  are disposed around substrate  14  either before or after placing the substrate between two longitudinal halves or clamshells of housing  12 . Here, housing  12  preferably comprises integral outer shells  30 . The two halves of housing  12  are closed around the assembly and welded together. Core  37  is optionally secured to outer shell  30  by, for example, welding, bonding, dimpling, and the like.  
         [0054]    During assembly with the “tourniquet method” for example, substrate  14  is wrapped with retention material  16 . End cone insulators  40  are disposed in operable communication with substrate  14  such that inboard ends  42  of the end cone insulators are supported by the substrate and retention material  16 . End cone insulators  40  are disposed around substrate  14  either before or after inserting the substrate into housing  12  through the open longitudinal edge. Housing  12  is closed around the assembly (retention material, substrate, and insulator(s)) and the open longitudinal edge is then welded closed. Core  37  is optionally secured to outer shell  30  either before or after the outer shells are applied to housing  12 .  
         [0055]    It should be recognized that housing  12  is illustrated by way of example only as including end cone insulator  40  having both screen  35  and inner core or tube  37 . Of course, the use of end cones insulators with or without one or both of screen  35  and core  37  with housings having integrated end cones are contemplated. Accordingly and as described above by way of exemplary embodiments, the end cone insulators are configured for use with housings of different designs, with various methods of inserting the substrate into the housing, and with various types of substrates.  
         [0056]    While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.