Patent Publication Number: US-2007113547-A1

Title: Exhaust treatment device with condensate gate

Description:
TECHNICAL FIELD  
      This disclosure relates generally to a method and apparatus for treating gases and, more particularly, to a method and apparatus for treating exhaust gases from an engine.  
     BACKGROUND  
      A diesel particulate filter (DPF) is a fluid treatment device that is commonly arranged within an exhaust gas stream of an internal combustion engine to trap particulates present in the exhaust gas. A DPF may include a cylindrical metal housing wrapped around a cylindrical ceramic filter element. A resilient mat may be compressed between the outer wall of the filter element and the inner wall of the metal housing. Because the mat is resilient and is compressed around the filter element by the housing wall, the mat may help secure the filter element within the housing while reducing vibratory effects between the housing and the filter.  
      A mat&#39;s effectiveness in securing a filter element within a housing may partly depend on the mat&#39;s ability to exert pressure on the filter element. The mat&#39;s exertion capacity may be decreased if the mat deteriorates or if the mat is exposed to undesirable conditions for a period of time. For example, if a mat is exposed to excessive moisture for a prolonged period, the mat&#39;s capacity to exert a holding pressure on a filter may be temporarily or permanently relaxed. Thus, it may be helpful to prevent a mat&#39;s overexposure to moisture within a DPF.  
      During operation of an internal combustion engine attached to a DPF, hot exhaust gases from the engine cause components within the DPF to heat up. When the engine is shut down, the DPF components cool, and condensation may occur on surfaces of the DPF components. This condensation, if allowed to pool around a mat, may adversely affect the mat&#39;s characteristics, as referenced above.  
      Various devices have been proposed for reducing a mat&#39;s exposure to moisture within a DPF. For example, in one such device, a cylindrical particulate filter is wrapped with a mat, and a sheet of metal is wrapped around the filter and mat to form a cylindrical metal housing. The cylindrical housing has a first outer diameter along most of its length. A longitudinal end of the cylindrical housing has a slightly decreased outer diameter with respect to the first outer diameter. The cylindrical housing is then tightly wrapped with a second, relatively longer piece of metal to form a second, longer cylindrical housing. A condensate catch volume is defined inside the second housing between the inner wall of the second housing and the outer wall of the first housing at the region of the first housing having a slightly decreased diameter. The DPF is then arranged in a vertical orientation so that the condensate catch volume faces upward. During operation, exhaust gas from an internal combustion engine is directed into a lower longitudinal end of the DPF and is exhausted from an upper longitudinal end of the DPF. When the engine is shut down, components within the DPF cool, and condensation is formed on the interior wall of the second housing. When the condensation drips down this wall, it is directed toward and held within the condensate catch volume rather than directly into the first housing (where the mat is arranged).  
      Exhaust treatment devices may be improved, for example by providing alternative, robust devices and methods for preventing or reducing moisture exposure within the devices.  
      The present invention is directed to overcome or improve one or more disadvantages associated with prior apparatus and methods for treating gases.  
     SUMMARY OF THE INVENTION  
      In one aspect of the present invention, a fluid treatment device is disclosed. The fluid treatment device may include a housing having a fluid treatment element therein. The device may further include at least one of (i) an inlet channel coupled to the housing and configured to direct fluid toward the fluid treatment element and (ii) an outlet channel coupled to the housing and configured to direct fluid away from the fluid treatment element. The at least one of the inlet channel and the outlet channel may include a shell member having an inner diameter and defining a fluid passage. The at least one of the inlet channel and the outlet channel may further include a gate member coupled to and arranged at least partially within the shell member and extending longitudinally from a first gate member portion having a diameter less than the inner diameter of the shell member to a second gate member portion having a diameter greater than the inner diameter of the shell member.  
      In another aspect of the present invention, a method of assembling a fluid treatment apparatus is disclosed. The method may include inserting a gate member at least partially into a fluid passage of a shell member having an inner diameter so that (i) a first portion of the gate member having a diameter less than the inner diameter of the shell member is arranged within the shell member and (ii) a second portion of the gate member having a diameter greater than the inner diameter of the shell member is arranged outside the shell member. The method may further include coupling the shell member to a housing having a fluid treatment element therein so that the shell member is configured to direct a flow of fluid toward or away from the fluid treatment element.  
      It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments or features of the invention and, together with the description, serve to explain principles of the invention. In the drawings,  
       FIG. 1  is a front cross-sectional view of a fluid treatment device;  
       FIG. 2  is a partial front cross-sectional view of the fluid treatment device of  FIG. 1 ; and  
       FIG. 3  is a partial front cross-sectional view of the fluid treatment device of  FIG. 1 . 
    
    
      Although the drawings depict exemplary embodiments or features of the present invention, the drawings are not necessarily to scale, and certain features may be exaggerated in order to better illustrate and explain the present invention. The exemplifications set out herein illustrate exemplary embodiments or features of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.  
     DETAILED DESCRIPTION  
      Reference will now be made in detail to embodiments or features of the invention, examples of which are illustrated in the accompanying drawings. Generally, the same or corresponding reference numbers will be used throughout the drawings to refer to the same or corresponding parts.  
      Referring now to  FIG. 1 , a fluid treatment device  10  for treating fluid is shown. More particularly,  FIG. 1  shows a diesel particular filter (DPF)  10  for treating exhaust gas from an engine. It should be appreciated that while a DPF is shown in the drawings and described herein for explanatory purposes, other types of fluid treatment devices  10  may be used in accordance with this disclosure. For example, various devices having fluid treatment elements, such as substrates, may be used.  
      The DPF  10  may include an element housing  14 , a fluid treatment element  18  arranged within the housing  14 , a mat  22  arranged between the housing  14  and the fluid treatment element  18 , and inlet and outlet channels, such as inlet and outlet portions  34 ,  42 , configured to permit fluid flow toward and away from the fluid treatment element  18 , respectively.  
      The housing  14  may form a metallic shell for the DPF  10  for receiving a stream of engine exhaust gas from an exhaust pipe  38  via the exhaust inlet portion  34 . The gas is directed from the inlet portion  34  through the fluid treatment element  18 , and out of the DPF  10  via the exhaust outlet portion  42 .  
      The housing  14  may be formed into a generally cylindrical shape and may be made from a suitable metallic material, such as steel, for handling hot exhaust gases.  
      The fluid treatment element  18  may be an exhaust treatment element  18 , such as a cylindrical ceramic substrate for treating exhaust gas from an engine. For example, as discussed earlier, a ceramic substrate  18  may be used to remove particulates from a stream of engine exhaust gas.  
      A mat  22  may be arranged between the housing  14  and the fluid treatment element  18 . For example, the mat  22  may be formed from a resilient material and may be compressed to a predetermined amount between an inner surface of the housing  14  and an outer surface of the fluid treatment element  18 . The mat  22  may take the form of a single piece of material covering a substantial portion of the outer surface of the fluid treatment  18  (as shown in  FIG. 1 ). However, it should be appreciated that, alternatively, the mat may take other forms, such as one or more relatively smaller strips of material, each covering a relatively small portion of the outer surface of the fluid treatment element  18 . The mat  22  may be formed from an intumescent material, a non-intumescent material, or a combination material having intumescent and non-intumescent properties, and may also function as a heat and/or vibration insulator between the fluid treatment element  18  and the housing  14 . In one embodiment, the mat  22  may be formed at least in part from alumina-silicate cloth.  
      Referring now to  FIG. 2 , the inlet portion  34  may form a fluid passage  46 . The inlet portion  34  may include first and second shell members  54 ,  58 , and insulating material  62  arranged between the first and second shell members  54 ,  58 .  
      In one embodiment, the first shell member  54  may be formed from a sheet of metal arranged to form a generally cylindrical cavity  59  having an inner diameter D 1 . An additional piece of material  60  (e.g., steel) may be sealingly attached to one end of the shell member  54 . An opening  60   a  may be formed in the piece of material  60  to permit insertion of the exhaust pipe  38  into the cavity  59 .  
      The second shell member  58  may similarly be formed from a sheet of metal arranged to form a generally cylindrical cavity  63  having an inner diameter D 2 . The second shell member  58  may be arranged around the first shell member such that an internal cavity  66  is formed between the first and second shell members  54 ,  58 . An additional piece of material  65  (e.g., steel) may be sealingly attached to one end of the second shell member  58 . An opening  65   a  may be formed in the piece of material  65  to permit insertion of the exhaust pipe  38  into the cavity  59 . As referenced above, insulating material  62  may be held within the cavity  66  and within a cavity  67  formed between the two pieces of material  60 ,  65 . Spacing elements  69 , such as clips  69 , may be arranged between the first and second shell members  54 ,  58  and between the pieces of material  60 ,  65  to maintained desired spaced relationships therebetween.  
      A gate member  50  may be configured at least partially within the fluid passage  46  of the inlet portion  34  for at least inhibiting flow of condensed fluid within the fluid treatment device  10 . In the embodiment of  FIGS. 1 and 2 , the gate member  50  is a generally frustoconical member arranged partially within the first shell member  54 . The gate member  50  extends longitudinally from a first gate member portion  50   a  having an outer diameter D 3  less than the inner diameter D 1  of the first shell member  54  to a second gate member portion  50   b  with an outer diameter D 4  greater than the inner diameter D 1  of the first shell member  54 . The first gate member portion  50   a  is arranged within the fluid passage  46  of the first shell member  54 , while the second gate member portion  50   b  is arranged outside the fluid passage  46  of the first shell member  54  and inside the second shell member  58 .  
      The gate member  50  may extend from the first gate member portion  50   a  into sealing engagement with the first shell member  54 , for example at an exterior surface location  70  on gate member  50  between the first and second gate member portions  50   a,    50   b . In one embodiment, the gate member  50  is welded to the first shell member  54  at location  70  ( FIG. 2 ) about all or substantially all of the circumference of gate member  50 . Thus, a fluid volume  74  may be defined within the first shell member  54  between an outer surface of the gate member  50  and an inner surface of the first shell member  54 . It should be appreciated that the gate member  50  may alternatively be welded to the first shell member  54  at various locations about the circumference of the gate member  50 .  
      The gate member  50  may also be coupled to the second shell member  58 . For example, the gate member  50  and the second shell member  58  may be welded together, for example at or proximate an end location  78  ( FIG. 2 ) of gate member  50 , either about all or substantially all of the entire circumference of the gate member  50  or at various locations thereon.  
      In the embodiment of  FIG. 2 , the gate member  50  extends from outside of the first shell member  54  into an opening  82  of the first shell member  54  and extends into the first shell member  54  a distance D 5  from the opening  82 .  
      The gate member  50  may be configured to extend into the fluid passage  46  a predetermined radial distance D 7  away from the first shell member  54 . For example, the outer diameter D 4  of the gate member portion  50   a  may be smaller than the inner diameter D 1  of the first shell member  54  by a value of twice the distance D 7 .  
      As illustrated in  FIG. 3 , the outlet portion  38  may be configured generally the same as the inlet portion  34 .  
      The first and second shell members  54 ′,  58 ′ of the outlet portion  38  may each have an aperture  86 ′ therein configured for permitting fluid (e.g., condensation) egress from within the first shell member  54 ′ and the outlet portion  38 . A tube  90 ′ may be inserted through the apertures  86 ′ for transmitting the fluid out of the outlet portion  38 . In the embodiment of  FIG. 3 , the aperture  86 ′ in the first shell member  54 ′ is arranged within the first shell member  54 ′ at least partially within a distance D 6 ′ from the opening  82 ′. The distance D 6 ′ may, in one embodiment, be less than or equal to the distance D 5 ′ so that if the fluid treatment device  10  is arranged in a vertical orientation and the outlet portion  38  is arranged atop the housing  14 , if condensate becomes held within the fluid volume  74 ′, the condensate may drain from the outlet section  38  via the tube  90 ′.  
     INDUSTRIAL APPLICABILITY  
      In an assembly operation, the fluid treatment element  18  may be wrapped with the mat  22  and the housing  14 . The fluid inlet portion  34  for carrying fluid toward the fluid treatment element  18  and the fluid outlet portion  38  for carrying fluid away from the fluid treatment element  18  may each be assembled by inserting the frustoconical gate member  50  partially into the fluid passage  46  formed by the first shell member  54 . The first gate member portion  50   a  may be arranged within the first shell member  54 , and the second gate member portion  50   b  may be arranged outside the first shell member  54 .  
      The gate member  50  may then be coupled to the first shell member  54 , for example via a welding process as referenced above. The welding process may form a weld around the outer surface of gate member  50  and the end, or an outer surface of, the first shell member  54 .  
      After insulating material  62  and clips  69  are placed around the outer surface of the first shell member  54 , the second shell member  58  may be arranged about the first shell member  54  and the gate member  50 . The gate member  50  then may be coupled to the second shell member  58 , for example via a welding process as referenced above. The welding process may form a weld around the end of, or around an inner surface of, gate member  50  and the end of, or an inner surface of, second shell member  58 . As shown in  FIG. 2 , the second shell member  58  may be arranged about the first shell member  54  and the gate member  50  such that a frustoconical portion of the gate member  50  extending from within the first shell member  54  to a position outside of the first shell member  54  extends within the second shell member  58 . As shown in  FIG. 2 , the second shell member  58  may extend beyond the longitudinal end of gate member portion  50   b , for example a predetermined distance D 8 . This extension of the second shell member  58  beyond the edge of gate member portion  50   b  may facilitate a welding process during which the gate member  50  is coupled to the second shell member  58 . It should be appreciated that the distance D 8  may be minimized or reduced to substantially zero in order to place the filter-side end of the gate member  50  as close as possible to the joint between the inlet/outlet portion  34 / 38  and the housing  14 , filter  18 , and mat  22  to better protect the mat  22  from condensate formed on most surface area in the inlet/outlet portion  34 / 38 .  
      The inlet and outlet portions  34 ,  38  of the device  10  may be coupled to the housing  14 , for example via a clamping operation during which each of the inlet and outlet portions  34 ,  38  is placed adjacent the housing  14  and a clamping element  94  is arranged about each of the portions  34 ,  38  to hold each of the portions  34 ,  38  together with the housing  14 . In the embodiment of  FIG. 1 , portions  34 ,  38  and housing  14  each contain mating flanges  98 ,  102 , around which a clamping element  94  may be arranged. It should be appreciated that one or more seals or gaskets may be arranged between the clamped components for sealing the junctions therebetween.  
      It should further be appreciated that the inlet and outlet portions  34 ,  38  may be arranged so that a larger diameter portion  50   b  of the gate member  50  may be arranged toward the filter element  18 , while a smaller diameter portion  50   a  of the gate member  50  may be arranged relatively away from the filter element  18 .  
      During operation of the fluid treatment device  10 , hot engine exhaust may be transmitted through the device  10  (for example via exhaust pipes  38 ,  38 ′), and the components thereof may be heated. When the engine is shut off, the components of the device  10  may cool, and condensate may form on them. The gate member  50  may operate to prevent or at least inhibit the condensate  50  from flowing toward the mat  18  within the housing  14 . For example, if the device  10  is arranged in a horizontal configuration (as shown in  FIGS. 1-3 ), condensate may gather in the fluid volume  74  and may pool between the gate member  50  and the piece of material  60  at the rear of the cavity  59 , rather than flowing from the inlet portion  54  into the housing  14  and toward the mat  22 .  
      If the device  10  is arranged in a vertical configuration, condensate may still flow into and gather in the fluid volume  74 ,  74 ′ rather than flowing from the inlet or outlet portion  54 ,  58  (whichever is placed atop the filter element  18 ) into the housing  14  and toward the mat  22 .  
      It should be appreciated that the orientation and form of the gate members  50  may facilitate holding condensate away from the filter element  18  and mat  22  during start up of an engine until the system heats up enough to evaporate the condensate. Moreover, the forms (e.g., the frustoconical aspects thereof) of the gate members  50  disclosed herein may facilitate relatively smooth exhaust flow transitions into and out of the filter element housing  14  during operation of the device  10 .  
      It should further be appreciated that since a gate member  50  may be attached to an inlet portion  34  or an outlet portion  38 , each of which may be detachable from the element housing  14 , each gate member  50  may be detached from the main housing  14  and adjusted, replaced, or maintained without having to work directly on the fluid treatment housing  14 .  
      From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit or scope of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and figures and practice of the invention disclosed herein. It is intended that the specification and disclosed examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims and their equivalents. Accordingly, the invention is not limited except as by the appended claims.