Patent Publication Number: US-10787951-B2

Title: Pipe and metal sheet subassembly for an exhaust treatment device

Description:
FIELD 
     The present disclosure relates to a pipe and metal sheet subassembly for an exhaust treatment device for receiving exhaust gas from a combustion engine. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Exhaust treatment devices, such as mufflers, may include subassemblies having one or more metal sheets and one or more pipes. A metal sheet may be a shell, an end cap, or an internal baffle, partition, or support. The pipes may direct exhaust flow and may be straight or curved. A curved pipe may include a 180° bend (e.g., J pipe or U pipe), a 90° bend, or multiple bends (e.g., S pipe). Curved pipes may be manufactured in a bending operation, resulting in a relatively large true position tolerance between the respective inlet and outlet centerlines. The present disclosure provides a pipe and metal sheet subassembly for an exhaust treatment device, and methods of manufacturing the pipe and metal sheet subassembly. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     In accordance with an aspect of the subject disclosure, a method of manufacturing a subassembly for an exhaust treatment device for receiving exhaust gas from a combustion engine includes providing a metal sheet and a one-piece pipe. The metal sheet includes a first aperture having a first size and a second aperture having a second size. The one-piece pipe has a first linear portion, a second linear portion, and a curved portion disposed between the first linear portion and the second linear portion. The first linear portion includes a third size. The second linear portion includes a fourth size. The second linear portion extends substantially parallel to the first linear portion. The method further includes defining the first size of the first aperture based on a first difference between the first size and the third size being less than or equal to a predetermined value. The method further includes defining the second size of the second aperture based on manufacturing tolerances of the one-piece pipe and the metal sheet. Defining the second size based on manufacturing tolerances assures that the second linear portion of the one-piece pipe will pass through the second aperture while the first linear portion of the one-piece pipe passes through the first aperture. The method further includes sealingly fixing the first linear portion of the one-piece pipe to the metal sheet. The method further includes expanding the second linear portion to increase the fourth size to an enlarged size until a second difference between the second size and the enlarged size is less than or equal to the predetermined value. The method further includes sealingly fixing the second linear portion of the one-piece pipe to the metal sheet. 
     In another aspect, a method of manufacturing a subassembly for an exhaust treatment device for receiving exhaust gas from a combustion engine includes providing a first metal sheet, a second metal sheet, and a one-piece pipe. The one-piece pipe has a first linear portion, a second linear portion, and a curved portion disposed between the first linear portion and the second linear portion. The method further includes defining a first size of a first aperture formed in the first metal sheet based on a first difference between the first size of the first aperture and a third size of the first linear portion being less than or equal to a predetermined value. The method further includes defining a second size of a second aperture formed in the second metal sheet based on manufacturing tolerances of the one-piece pipe, the first metal sheet, and the second metal sheet. Defining the second size based on manufacturing tolerances assures that the second linear portion of the one-piece pipe will pass through the second aperture while the first linear portion of the one-piece pipe passes through the first aperture. The method further includes sealingly fixing the first linear portion of the one-piece pipe to the first metal sheet. The method further includes expanding the second linear portion of the one-piece pipe to increase a fourth size of the second linear portion to an enlarged size until a second difference between the second size and the enlarged size is less than or equal to the predetermined value. The method further includes sealingly fixing the second linear portion of the one-piece pipe to the second metal sheet. 
     In yet another aspect, an exhaust treatment device for receiving exhaust gas from a combustion engine includes a shell, a first metal sheet, a second metal sheet, and a one-piece pipe. The first metal sheet has a first periphery. The first periphery fixedly engages the shell. The second metal sheet has a second periphery. The second periphery fixedly engages the shell. The one-piece pipe is configured to be sealingly fixed to at least one of the shell, the first metal sheet, and the second metal sheet. The one-piece pipe has a first linear portion, a second linear portion, and a curved portion disposed between the first linear portion and the second linear portion. The first linear portion of the one-piece pipe extends through a first aperture that is formed in one of the shell, the first metal sheet, or the second metal sheet. The first aperture has a first size. The first size of the first aperture is defined based on a first difference between the first size and a third size of the first linear portion of the one-piece pipe being less than or equal to a predetermined value. The second linear portion of the one-piece pipe extends through a second aperture that is formed in one of the shell, the first metal sheet, or the second metal sheet. The second aperture has a second size. The second size of the second aperture is defined based on manufacturing tolerances of the one-piece pipe. Defining the second size based on manufacturing tolerances assures that the second linear portion of the one-piece pipe is configured to pass through the second aperture when the first linear portion of the one-piece pipe passes through the first aperture. The second linear portion is configured to be expanded to increase a fourth size of the second linear portion to an enlarged size until a second difference between the second size of the second aperture and the enlarged size is less than or equal to the predetermined value. The first linear portion of the one-piece pipe is configured to be sealingly fixed to a first surface adjacent to the first aperture. The second linear portion of the one-piece pipe is configured to be sealingly fixed to a second surface adjacent to the second aperture. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is an isometric view of a muffler having a pipe and metal sheet subassembly according to the principles of the present disclosure; 
         FIG. 2  is a sectional view of the subassembly of  FIG. 1 ; 
         FIG. 3  is a sectional view of the subassembly of  FIG. 2 , showing a portion of the pipe in an enlarged state; 
         FIG. 4  is a partial sectional view of the subassembly of  FIG. 1 ; 
         FIG. 5  is a partial sectional view of the subassembly of  FIG. 4 , showing the portion of the pipe in the enlarged state; 
         FIG. 6  is a partial sectional view of another subassembly according to the principles of the present disclosure; 
         FIG. 7  is a flowchart of a method of manufacturing the subassembly of  FIG. 1 ; and 
         FIG. 8  is a flowchart of a method of manufacturing another subassembly for an exhaust treatment device according to the principles of the present disclosure. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     With reference to  FIG. 1 , a muffler  10  is provided that may receive exhaust gas from one or more exhaust pipes connected to a combustion engine (not shown). The muffler  10  may be shaped to fit within a given available space on a vehicle (not shown). For example, in some configurations, the muffler  10  may be shaped to fit around a spare tire well of the vehicle and/or other components at or near an undercarriage of the vehicle. 
     The muffler  10  may include a shell  12  extending along a longitudinal axis  14 , a first internal baffle  16 , a second internal baffle  18 , an inlet pipe  20 , a first outlet pipe assembly  22 , a second outlet pipe assembly  24 , and one or more internal communication pipes  26 . The shell  12  may be tubular and may be formed from a metal sheet. A first end cap  28  and a second end cap  30 , which may be metal sheets or plates, may be disposed at respective axial ends of the shell  12  and may cooperate with the shell  12  to define an internal volume  32 . A first periphery  34  of the first end cap  28  may be sealingly fixed to the shell  12 . A second periphery  36  of the second end cap  30  may be sealingly fixed to the shell  12 . More specifically, the first and second end caps  28 ,  30  may be welded, mechanically locked, or otherwise sealingly fixed onto the axial ends of the shell  12 . The above components are merely exemplary, and in other embodiments, a muffler according to the principles of the present disclosure may include fewer components (e.g., a single outlet pipe assembly, by way of non-limiting example), or additional components (e.g., a third internal baffle, by way of non-limiting example). 
     The first and second internal baffles  16 ,  18 , which may be metal sheets or plates, are disposed within the shell  12  and between the first and second end caps  28 ,  30 . That is, the first and second internal baffles  16 ,  18  may be disposed within the internal volume  32 . The first internal baffle  16  may include a third periphery  38  and the second internal baffle  18  may include a fourth periphery  40 . The third and fourth peripheries  38 ,  40  may be shaped to generally match the contours of an inner circumferential wall  41  of the shell  12 . The third and fourth peripheries  38 ,  40  of the first and second internal baffles  16 ,  18  may be welded, mechanically locked, or otherwise sealingly fixed to the inner circumferential wall  41  of the shell  12 . 
     The first and second internal baffles  16 ,  18  may divide the internal volume  32  into a first chamber  42 , a second chamber  44 , and a third chamber  46 . The first chamber  42  may be defined by the shell  12 , the first end cap  28 , and the first internal baffle  16 . The second chamber  44  may be defined by the shell  12 , the second end cap  30 , and the second internal baffle  18 . The third chamber  46  may be disposed between the first chamber  42  and the second chamber  44 . The third chamber  46  may be defined by the shell  12 , the first internal baffle  16 , and the second internal baffle  18 . 
     The first internal baffle  16  may include a first aperture  48 , a second aperture  50 , a third aperture  52 , and one or more fourth apertures  54 . The second internal baffle  18  may include a fifth aperture  56 , a sixth aperture  58 , a seventh aperture  60 , and one or more eighth apertures  62 . The second internal baffle  18  may also include a plurality of openings  64 . The shell  12  may include an inlet aperture  66 . The first and second end caps  28 ,  30  may include respective first and second outlet apertures  68 ,  70 . 
     The inlet pipe  20  may be at least partially disposed in the third chamber  46  and may extend through the inlet aperture  66  in the shell  12 . The inlet pipe  20  may include a first inlet opening  72  that may be fluidly coupled with the exhaust pipe (not shown). The inlet pipe  20  may include a first outlet opening (not shown) in fluid communication with the third chamber  46 . The inlet pipe  20  may extend through a support plate  76  that is disposed substantially parallel to the longitudinal axis  14  of the shell  12 . The support plate  76  may be disposed at least partially within the third chamber  46  and may extend between the first internal baffle  16  and the second internal baffle  18 . 
     The first outlet pipe assembly  22  may be at least partially disposed in the first, second, and third chambers  42 ,  44 ,  46 . The first outlet pipe assembly  22  may include a first tube (or “one-piece pipe”)  78  and a second tube  80 . The first tube  78  may include a second inlet opening  82  that is in fluid communication with the second chamber  44 . The first tube  78  may extend from the third chamber  46 , through the sixth aperture  58  of the second internal baffle  18 , into the third chamber  46 , through the second aperture  50  of the first internal baffle  16  into the first chamber  42 , bend around an angle of about 180°, extend through the first aperture  48  of the first internal baffle  16 , and back into the third chamber  46 . The first tube  78  may be fluidly sealed to and in fluid communication with the second tube  80  at a first joint  84  in the third chamber  46 . The second tube  80  may extend through the fifth aperture  56  in the second internal baffle  18  into the second chamber  44 , and through the second outlet aperture  70 . The second tube  80  may include a second outlet opening  86  that is open to the ambient environment surrounding the muffler  10  or the outlet opening  86  could be coupled to another exhaust system component outside of the muffler  10  (e.g., a tailpipe, not shown). 
     The second outlet pipe assembly  24  may be at least partially disposed in the first, second, and third chambers  42 ,  44 ,  46 . The second outlet pipe assembly  24  may include a third tube  88  and a fourth tube  90 . The third tube  88  may include a third inlet opening  92  that is in fluid communication with the second chamber  44 . The third tube  88  may extend from the second chamber  44 , through the seventh aperture  60  in the second internal baffle  18 , into the third chamber  46 , through the third aperture  52  in the first internal baffle  16 , and into the first chamber  42 . The third tube  88  may be fluidly sealed to and in fluid communication with the fourth tube  90  at a second joint (not shown) in the first chamber  42 . The fourth tube  90  may extend from the first chamber  42  through the first outlet aperture  68 . The fourth tube  90  may include a third outlet opening (not shown) that is open to the ambient environment surrounding the muffler  10  or the outlet opening could be coupled to another exhaust system component outside of the muffler  10  (e.g., a tailpipe, not shown). 
     The internal communication pipes  26  may respectively extend through the fourth apertures  54  in the first internal baffle  16 . The internal communication pipes  26  may be at least partially disposed in the first and third chambers  42 ,  46  to permit fluid communication between the first and third chambers  42 ,  46 . The eighth apertures  62  and the plurality of openings  64  in the second internal baffle  18  may permit fluid communication between the second and third chambers  44 ,  46 . 
     Together, the first internal baffle  16  and the first tube  78  (hereinafter “one-piece pipe”) may be referred to as a pipe and metal sheet subassembly  110 . In other embodiments, “pipe and metal sheet subassembly” may refer to any subassembly for use in an exhaust treatment device that includes a curved one-piece pipe extending through apertures in one or more metal sheets. The curved one-piece pipe may be any one-piece pipe that includes a curved portion disposed between and fluidly connecting first and second linear portions. A metal sheet may be a shell, an end cap, or an internal baffle, partition, or support, by way of non-limiting example. 
     As best shown in  FIGS. 2 and 3 , the one-piece pipe  78  may include a first linear portion  112 , a second linear portion  114 , and a curved portion  116  disposed between and fluidly connecting the first and second linear portions  112 ,  114 . As shown in  FIG. 4 , the first and second apertures  48 ,  50  may include respective first and second centerlines  118 ,  120 . A first tolerance between the first and second centerlines  118 ,  120  may be relatively tight (i.e., small). The first and second linear portions  112 ,  114  of the one-piece pipe  78  may include respective third and fourth centerlines  122 ,  124 . A second tolerance between the third and fourth centerlines  122 ,  124  may be relatively large. The relatively large second tolerance may result from the bending operation used to form the one-piece pipe. 
     The large second tolerance between the third and fourth centerlines  122 ,  124  of the one-piece pipe  78  may result in a difficult and/or costly assembly of the one-piece pipe  78  to the first internal baffle  16 . More specifically, if the first and second apertures  48 ,  50  were sized to match (or slightly exceed) respective outer sizes of the first and second linear portions  112 ,  114 , a given one-piece pipe  78  may not fit into the first and second apertures  48 ,  50  of the first internal baffle  16  at all. That is, the second linear portion  114  of the one-piece pipe  78  may be unable to pass through the second aperture  50  as the first linear portion  112  of the one-piece pipe  78  passes through the second aperture  50 . A nonconforming one-piece pipe  78  may be deformed and forced into position, or scrapped. 
     In another example, if both the first and second apertures  48 ,  50  were oversized to accommodate the first tolerance of the one-piece pipe  78 , assembly of the one-piece pipe  78  to the first internal baffle  16  may be difficult or result in a joint having a poor quality. More specifically, when welding is used to assemble the one-piece pipe  78  to the first internal baffle  16 , a circumferential gap between the linear portions  112 ,  114  of the one-piece pipe  78  and the respective apertures  48 ,  50  may be ideally be less than or equal to a predetermined value. When a robotic weld process is used, the predetermined value may be less than or equal to about 1.5 mm, optionally less than or equal to about 1.3 mm, optionally less than or equal to about 1.1 mm, and optionally less than or equal to about 1.0 mm, by way of non-limiting example. If the first and second apertures  48 ,  50  were oversized, the circumferential gap may be greater than the predetermined value and the weld joint may be weak and/or include fluid leak paths. 
     Referring to  FIGS. 2-5 , the pipe and metal plate subassembly  110  is shown. The subassembly  110  may include the one-piece pipe  78  and the first internal baffle  16 . The first aperture  48  of the first internal baffle  16  may include a first size  126  and the second aperture  50  of the first internal baffle  16  may include a second size  128 . In some embodiments, the first and second apertures  48 ,  50  may be circular and the first and second sizes  126 ,  128  may be respective first and second diameters. The first linear portion  112  of the one-piece pipe  78  may include a third size  130 . The second linear portion  114  of the one-piece pipe  78  may include a fourth size  132 . In some embodiments, the first and second linear portions  112 ,  114  may be substantially cylindrical and the third and fourth sizes  130 ,  132  may be respective first and second outer diameters. 
     A difference or gap (the “first difference”) between the first size  126  of the first aperture  48  and the third size  130  of the first linear portion  112  may be less than or equal to the predetermined value. Thus, a tight fit may be provided between the first linear portion  112  and the first aperture  48  such that when the first linear portion  112  is inserted into the first aperture  48 , the first linear portion  112  of the one-piece pipe  78  may be welded to the first internal baffle  16 . More specifically, an outer surface  134  of the first linear portion  112  may be welded to a first surface  136  of the first internal baffle  16  that is adjacent to the first aperture  48 . 
     A difference or gap (the “oversized gap”) between the second size  128  and the fourth size  132  may be greater than the predetermined value ( FIGS. 2 and 4 ). The oversized gap may assure that the second linear portion  114  can pass through the second aperture  50  when the first linear portion  112  passes through the first aperture  48 . Thus, various one-piece pipes  78  having the large manufacturing tolerance may all fit within the first and second apertures  48 ,  50  of the first internal baffle  16 . For example, as shown in  FIG. 4 , the one-piece pipe  78  may include the second linear portion  112  portion that is disposed to the right of the second centerline  120  of the second aperture  50 . 
     The oversized gap may be too large to enable the second linear portion  114  of the one-piece pipe  78  to be properly welded to the first internal baffle  16 . Thus, after the first and second linear portions  112 ,  114  of the one-piece pipe  78  are inserted into respective first and second apertures  48 ,  50 , the second linear portion  114  can be expanded from the fourth size  132  ( FIGS. 2 and 4 ) to an enlarged size  138  ( FIGS. 3 and 5 ). When the second linear portion  114  has the enlarged size  138 , the second centerline  120  of the second aperture  50  may be aligned with the fourth centerline  124  of the second linear portion  114 . A difference or gap (the “second difference”) between the second size  128  of the second aperture  50  and the enlarged size  138  of the second linear portion  114  of the one-piece pipe  78  may be less than or equal to the predetermined value. The second linear portion  114  may have the enlarged size  138  at an enlarged region  139  ( FIG. 3 ). The enlarged region  139  may be disposed adjacent to the second aperture  50 . Thus, a tight fit may be provided between the second linear portion  114  and the second aperture  50  such that the second linear portion  114  can be welded to the first internal baffle  16 . More specifically, an outer surface  140  of the second linear portion  114  may be welded to a second surface  142  of the first internal baffle  16  that is adjacent to the second aperture  50 . Although the enlarged region  139  is shown as a discrete axial location adjacent to the second aperture  50 , in other embodiments the second linear portion  114  may alternatively be expanded along a greater portion of its length. For example, the second linear portion  114  may be expanded along a length extending from an area adjacent to the second aperture  50  the second inlet opening  82 . 
     Although the subassembly  110  is shown and described as being disposed in the muffler  10 , the muffler  10  is merely exemplary and the subassembly  110  may be used in other mufflers or other exhaust treatment devices. For example, the subassembly  110  may be used in any exhaust treatment device that includes at least one metal sheet (e.g., a shell, an end cap, or an internal baffle, partition, or support), and a curved one-piece pipe. 
     As discussed above, an oversized second aperture  50  enables the use of a variety of different one-piece pipes  78  having the large manufacturing tolerance. With reference to  FIG. 6 , an alternate subassembly  146  is provided. The subassembly  146  may include a baffle  16 A having first and second apertures  48 A,  50 A and a one-piece pipe  78 A including first and second linear portions  112 A,  114 A. The first and second apertures  48 A,  50 A may have first and second centerlines  118 A,  120 A. The baffle  16 A having first and second apertures  48 A,  50 A may be similar to the first internal baffle  16  having first and second apertures  48 ,  50  of  FIG. 4 . The first and second linear portions  112 A,  114 A may have third and fourth centerlines  122 A,  124 A. In contrast to the one-piece pipe  78  of  FIG. 4 , the fourth centerline  124 A may be disposed to the left of the second centerline  120 A. Thus, a distance between the third and fourth centerlines  122 A,  124 A of the one-piece pipe  78 A of  FIG. 6  may be less than a distance between the third and fourth centerlines  122 ,  124  of the one-piece pipe  78  of  FIG. 4 . However, the second linear portions  114 ,  114 A of both one-piece pipes  78 ,  78 A can pass through the respective second apertures  50 ,  50 A when the respective first linear portions  112 ,  112 A pass through respective first apertures  48 ,  48 A. Thus, as demonstrated by  FIGS. 4 and 6 , the one-piece pipe  78  of  FIG. 4  and the one-piece pipe  78 A of  FIG. 6  are equally capable of being inserted in the apertures of the respective baffles without rework or distortion. 
     With reference to  FIGS. 2-5 and 7 , a method  150  of assembling the subassembly  110  will be described. As shown in  FIG. 7 , at step  154  of the method  150 , the one-piece pipe  78  and a metal sheet (e.g., the first internal baffle  16 ) are provided. Although the metal sheet is shown as the first internal baffle  16 , in other embodiments, the metal sheet may be a shell (similar to the shell  12  of  FIG. 1 ), an end cap (similar to the first or second end caps  28 ,  30  of  FIG. 1 ), or other baffles, partitions, or supports, by way of non-limiting example. Thus, the metal sheet may be any component for an exhaust treatment device having two or more apertures for receiving portions of a curved one-piece pipe. 
     The one-piece pipe  78  may include the first linear portion  112 , the second linear portion  114 , and the curved portion  116  disposed between and fluidly connecting the first and second linear portions  112 ,  114 . The first and second linear portions  112 ,  114  may be substantially parallel to one another. While the first linear portion  112  is shown as having a shorter length than the second linear portion  114 , in other embodiments, the first linear portion  112  may be longer than the second linear portion  114  or the first and second linear portions  112 ,  114  may have substantially the same length. Furthermore, although the curved portion  116  is shown as extending through an angle of about 180°, 180° is merely exemplary and the curved portion  116  may extend through other angles that result in the first and second portions  112 ,  114  being substantially parallel. For example, the curved portion  116  may include two bends of about 90°. The first linear portion  112  may have the third size  130  and the second linear portion  114  may have the fourth size  132 . The third and fourth sizes  130 ,  132  may be the same or different. Although the one-piece pipe  78  is shown as substantially cylindrical (i.e., the third and fourth sizes  130 ,  132  are first and second outer diameters), the cylindrical one-piece pipe  78  is merely exemplary and other shapes are contemplated. For example, in other embodiments, a one-piece pipe  78  may have an elongated cross section. 
     The first internal baffle  16  may include the first and second apertures  48 ,  50 . The first aperture  48  may have the first size  126  and the second aperture  50  may have the second size  128 . The first size  126  may be defined based on the first difference between the first size  126  and the third size  130  of the first linear portion  112  of the one-piece pipe  78  being less than or equal to the predetermined value. The second size  128  may be defined based on manufacturing tolerances of the one-piece pipe  78  and the first internal baffle  16  to assure that the second linear portion  114  of the one-piece pipe  78  will pass through the second aperture  50  when the first linear portion  112  of the one-piece pipe  78  passes through the first aperture  48 . Thus, the oversized gap between the second size  128  of the second aperture  50  and the fourth size  132  of the second linear portion  114  of the one-piece pipe  78  may be greater than the predetermined value. 
     At step  158  of the method  150 , the one-piece pipe  78  may be inserted into the first and second apertures  48 ,  50  of the first internal baffle  16 . More specifically, the first linear portion  112  of the one-piece pipe  78  may be inserted into the first aperture  48  and the second linear portion  114  of the one-piece pipe  78  may be inserted into the second aperture  50 . The third centerline  122  of the first linear portion  112  may be substantially aligned with the first centerline  118  of the first aperture  48  ( FIG. 4 ). The first tolerance between the first linear portion  112  and the first aperture  48  may be relatively tight. The first difference between the first aperture  48  and the first linear portion  112  may be less than or equal to the predetermined value to enable the first linear portion  112  to be welded to the first internal baffle  16 . 
     At step  162  of the method  150 , the first linear portion  112  of the one-piece pipe  78  may be sealingly fixed to the first internal baffle  16 . Sealingly fixing may include welding. More specifically, the outer surface  134  of the first linear portion  112  may be welded to the first internal baffle  16  at a first surface  136  adjacent to the first aperture  48 . After the welding, a position of the one-piece pipe  78  may be fixed with respect to the first interior baffle  16 . Due to manufacturing tolerances, the second linear portion  114  may be disposed off center with respect to the second aperture  50 . More specifically, the second centerline  120  and the fourth centerline  124  may be offset from one another. For example, the fourth centerline  124  may be disposed to the right (see  FIG. 4 ) or the left (see second centerline  120 A and fourth centerline  124 A of  FIG. 6 ) of the second centerline  120 . 
     At step  166  of the method  150 , the the second linear portion  114  of the one-piece pipe  78  may be expanded from the fourth size  132  to the enlarged size  138 . The second linear portion  114  may be expanded using a ridge locking machine, for example. However, the use of a ridge locking machine is merely exemplary and the second linear portion  114  may alternatively be expanded by other tools, such as an expansion mandrel, by way of non-limiting example. 
     At step  170  of the method  150 , the second linear portion  114  of the one-piece pipe  78  may be sealingly fixed to the first internal baffle  16 . Sealingly fixing may include welding. More specifically, the outer surface  140  of the second linear portion  114  may be welded to the first internal baffle  16  at the second surface  142  adjacent to the second aperture  50 . 
     The weld locations (i.e., the location where the first linear portion  112  of the one-piece pipe  78  is fixed to the first internal baffle  16  adjacent to the first aperture  48  and the location where the second linear portion  114  of the one-piece pipe  78  is fixed to the first internal baffle  16  adjacent to the second aperture  50 ) for the subassembly  110  may be advantageously consistently located at the same location on the first internal baffle  16 . That is, despite the variance in position of the third centerline  122  of the second linear portion  114  with respect to the third centerline  122  of the first linear portion  112 , all one-piece pipes  78  having the manufacturing tolerance can be assembled to the first internal baffle  16  in a similar manner and with an identical welding process. The consistent weld location is particularly advantageous where robotic welding process is used because the welds can always be applied in the same place. The consistent weld locations can lead to cost reduction and improved joints. 
     The method  150  may optionally further include assembling the subassembly to an exhaust treatment device, such as a muffler (e.g., the muffler  10  of  FIG. 1 ). In one example, the subassembly  110  is fully assembled prior to placing the subassembly  110  within a shell of the exhaust treatment device. In another example, the first internal baffle  16  may already be fixed within the shell when the subassembly  110  is manufactured according to the method  150 . Furthermore, in other embodiments, some of the steps of the method  150  may be performed in a different order. For example, step  166  may be completed prior to step  162 . 
     Referring to  FIGS. 2-5 and 8 , a method  190  of manufacturing another subassembly for an exhaust treatment device will be described. As shown in  FIG. 8 , at step  194  of the method  190 , a one-piece pipe and first and second metal sheets may be provided. The one-piece pipe may include a 180° curved portion (such as a J pipe similar to the one-piece pipe  78  of  FIG. 1 , or a U pipe), a 90° curved portion, multiple curved portions (such as an S pipe), or any other shape having a curved portion disposed between first and second linear portions. A metal sheet may be a shell (e.g., the shell  12  of  FIG. 1 ), an end cap (e.g., the first and second end caps  28 ,  30  of  FIG. 1 ), or an internal baffle (e.g., first and second internal baffles  16 ,  18  of  FIG. 1 ). 
     A first aperture may be defined in the first metal sheet. A second aperture may be defined in the second metal sheet. In one example, the first metal sheet is a shell, the second metal sheet is an internal baffle, and the one-piece pipe includes a 90° bend (i.e., the first and second linear portions are substantially perpendicular to one another). In another example, the first metal sheet is an internal baffle, the second metal sheet is an end cap, and the one-piece pipe is S-shaped (i.e., the first and second linear portions are substantially parallel to one another). In yet another example, the first metal sheet is an end cap, the second metal sheet is a shell, and the one-piece pipe includes a 90° bend (i.e., the first and second linear portions are substantially perpendicular to one another). In yet another example, the first metal sheet is a first internal baffle, the second metal sheet is a second internal baffle, and the one-piece pipe includes coaxial first and second linear portions and a curved portion that extends through a 90° angle, a 180° angle, and another 90° angle. 
     A first size of the first aperture may be defined based on a difference between the first size of the first aperture and a third size of a first linear portion of the one-piece pipe being less than or equal to a predetermined value. A second size of the second aperture may be defined based on manufacturing tolerances of the one-piece pipe to assure that a second linear portion of the one piece pipe will pass through the second aperture when the first linear portion of the one-piece pipe passes through the first aperture. 
     At step  198  of the method  190 , the one-piece pipe may be inserted into the first and second apertures. Step  198  may be similar to step  158  of the method  150  of  FIG. 7 . At step  202 , the first linear portion of the one-piece pipe may be sealingly fixed (such as welded) to the first metal sheet. Step  202  may be similar to step  162  of the method  150  of  FIG. 7 . At step  206 , the second linear portion of the one-piece pipe may be expanded to increase the second linear portion from the fourth size to an enlarged size. Step  206  may be similar to step  166  of the method  150  of  FIG. 7 . At step  210 , the second linear portion may be sealingly fixed (such as welded) to the second metal sheet. Step  210  may be similar to step  170  of the method  150  of  FIG. 7 . 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.