Patent Publication Number: US-2022220874-A1

Title: Exhaust system and muffler

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application 62/858,546 filed Jun. 7, 2019, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to an exhaust system for an engine. More particularly, the present disclosure relates to a muffler of an exhaust system for an engine. 
     BACKGROUND 
     An exhaust system for an internal combustion engine employs a muffler in order to dampen exhaust noise generated by the engine. In a multi-cylinder internal combustion engine, two different exhaust streams can be generated by two different banks of cylinders. The two exhaust streams can flow into the muffler from two different portions of an exhaust manifold through two different exhaust pipes. In many situations, the two exhaust streams can collide and mix within the muffler and can further exit the muffler in two different exhaust stream or a combined single exhaust stream. The collision and mixing of the two exhaust streams can result in an undesired backpressure within the muffler. In some situations, the collision and mixing of the two exhaust streams can result in an increased exhaust noise within the muffler. Hence, there is a need for an improved muffler for such applications. 
     Given description covers one or more above mentioned problems and discloses a method and a system to solve the problems. 
     SUMMARY 
     In an aspect of the present disclosure, a muffler for use with an internal combustion engine is provided. The muffler includes a first tube. The first tube includes a first inlet portion defining a first inlet configured to receive a first exhaust stream. The first inlet portion is disposed along a first axial plane. The first tube also includes a first outlet portion defining a first outlet and disposed along a second axial plane. The second axial plane is vertically spaced from the first axial plane. The first tube further includes a first intermediate portion extending from the first inlet portion to the first outlet portion. The first intermediate portion is fluidly coupled to the first inlet portion and the first outlet portion. The muffler also includes a second tube. The second tube includes a second inlet portion defining a second inlet configured to receive a second exhaust stream. The second inlet portion is spaced apart from the first inlet portion and disposed along a third axial plane. The second tube also includes a second outlet portion spaced apart from the first outlet portion and defining a second outlet. The second outlet portion is disposed along a fourth axial plane that is vertically spaced from the third axial plane. The second tube further includes a second intermediate portion extending from the second inlet portion to the second outlet portion. The second intermediate portion is fluidly coupled to the second inlet portion, the second outlet portion and the first intermediate portion. The first intermediate portion and the second intermediate portion cross each other and are at least partially stacked on each other. 
     In another aspect of the present disclosure, a muffler for use with an internal combustion engine is provided. The muffler includes a first tube configured to receive a first exhaust stream. The first tube includes a first inlet portion, a first outlet portion spaced apart from the first inlet portion, and a first intermediate portion extending between the first inlet portion and the first outlet portion. The muffler also includes a second tube configured to receive a second exhaust stream. The second tube includes a second inlet portion, a second outlet portion spaced apart from the second inlet portion, and a second intermediate portion extending between the second inlet portion and the second outlet portion. The first intermediate portion and the second intermediate portion cross each other, are at least partially stacked on each other, and are in fluid communication with each other. 
     In yet another aspect of the present disclosure, an exhaust system for use with an internal combustion engine having a first row of cylinders and a second row of cylinders is provided. The exhaust system includes a first pipe adapted to receive a first exhaust stream from the first row of cylinders. The exhaust system also includes a second pipe adapted to receive a second exhaust stream from the second row of cylinders. The exhaust system further includes a muffler. The muffler includes a first tube fluidly coupled to the first pipe. The first tube includes a first inlet portion defining a first inlet configured to receive the first exhaust stream. The first inlet portion is disposed along a first axial plane. The first tube also includes a first outlet portion defining a first outlet and disposed along a second axial plane. The second axial plane is vertically spaced from the first axial plane. The first tube further includes a first intermediate portion extending from the first inlet portion to the first outlet portion. The first intermediate portion is fluidly coupled to the first inlet portion and the first outlet portion. The muffler also includes a second tube fluidly coupled to the second pipe. The second tube includes a second inlet portion defining a second inlet configured to receive the second exhaust stream. The second inlet portion is spaced apart from the first inlet portion and disposed along a third axial plane. The second tube also includes a second outlet portion spaced apart from the first outlet portion and defining a second outlet. The second outlet portion is disposed along a fourth axial plane that is vertically spaced from the third axial plane. The second tube further includes a second intermediate portion extending from the second inlet portion to the second outlet portion. The second intermediate portion is fluidly coupled to the second inlet portion, the second outlet portion and the first intermediate portion. The first intermediate portion and the second intermediate portion cross each other and are at least partially stacked on each other. 
     Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an exemplary schematic representation of an exhaust system associated with an engine, according to an aspect of the present disclosure; 
         FIG. 2A  is an exploded perspective view of a muffler of the exhaust system of  FIG. 1 , according to an aspect of the present disclosure; 
         FIG. 2B  is a perspective view of the muffler of  FIG. 2A  in an assembled condition, according to an aspect of the present disclosure; 
         FIG. 2C  is another perspective view of the muffler of  FIG. 2A  in the assembled condition, according to an aspect of the present disclosure; 
         FIG. 2D  is another perspective view of the muffler of  FIG. 2B  without a casing, according to an aspect of the present disclosure; 
         FIG. 2E  is another perspective view of the muffler of  FIG. 2C  without the casing, according to an aspect of the present disclosure; 
         FIG. 2F  is a side view of the muffler of  FIG. 2E , according to an aspect of the present disclosure; 
         FIG. 2G  is a top view of the muffler of  FIG. 2E , according to an aspect of the present disclosure; 
         FIG. 2H  depicts a side view of the muffler of  FIG. 2E , according to an aspect of the present disclosure; 
         FIG. 2I  depicts a side view of the muffler of  FIG. 2E , according to an aspect of the present disclosure; 
         FIG. 2J  depicts a side view of the muffler of  FIG. 2E , according to an aspect of the present disclosure; 
         FIG. 3  is a cross-sectional view of the muffler of  FIG. 2D  along a section S-S′, according to an aspect of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Aspects of the disclosure generally relate to a muffler that provides a simple, efficient, and cost-effective method of reducing exhaust noise downstream of the muffler. The muffler includes first and second tubes that provide substantially separate flow paths for multiple exhaust streams. The first and second tubes reduce direct collision between the multiple exhaust streams, which in turn reduces drag and backpressure within the muffler. Also, as the multiple exhaust streams cross each other in a common chamber located between the first and second tubes, the common chamber provides limited interaction and mixing of the multiple exhaust streams. This results in cancelling half engine order noise generated in each of first and second pipes, which reduces fluid noise within the muffler. As a result, overall exhaust noise is reduced downstream of the muffler relative to a conventional muffler having substantial interaction and mixing of different exhaust streams. 
     Wherever possible, the same reference numbers will be used throughout the drawings to refer to same or like parts. Referring to  FIG. 1 , an exemplary schematic representation of an exhaust system  102  coupled to an engine  104  is illustrated. The engine  104  can be any internal combustion engine powered by a fuel, such as gasoline, diesel, natural gas, or any other fuel, or a combination thereof. As illustrated, the engine  104  is a multi-cylinder engine. Accordingly, the engine  104  includes two rows of cylinders, such as a first row of cylinders  106  and a second row of cylinders  108 . The first row of cylinders  106  and the second row of cylinders  108  can correspond to two cylinder banks of the engine  104 . In the illustrated embodiment, each of the first row of cylinders  106  and the second row of cylinders  108  includes three cylinders. In other embodiments, each of the first row of cylinders  106  and the second row of cylinders  108  can include any number of cylinders, based on application requirements. Also, in the illustrated embodiment, the engine  104  has a V-configuration. In other embodiments, the engine  104  can have any other configurations, such as an inline or straight configurations, or can be based on other application requirements. 
     The exhaust system  102  includes a first exhaust manifold  110  and a second exhaust manifold  112 . The first exhaust manifold  110  is coupled to the first row of cylinders  106 . Accordingly, the first exhaust manifold  110  is adapted to receive a first exhaust stream “E 1 ” from the first row of cylinders  106 . The second exhaust manifold  112  is coupled to the second row of cylinders  108 . Accordingly, the second exhaust manifold  112  is adapted to receive a second exhaust stream “E 2 ” from the second row of cylinders  108 . Additionally, the engine  104  can include components and/or systems not described herein, such as an engine block, a cylinder head, a valve assembly, an intake manifold, a cooling system, a lubrication system, an air delivery system, a turbocharger, a supercharger, or other peripherals based on application requirements. 
     The exhaust system  102  also includes a muffler  114 . The muffler  114  is coupled to each of the first exhaust manifold  110  and the second exhaust manifold  112 . More specifically, the muffler  114  is coupled to the first exhaust manifold  110  via a first pipe  116 . The first pipe  116  is adapted to provide flow of the first exhaust stream “E 1 ” from the first exhaust manifold  110  to the muffler  114 . Also, the muffler  114  is coupled to the second exhaust manifold  112  via a second pipe  118 . The second pipe  118  is adapted to provide flow of the second exhaust stream “E 2 ” from the second exhaust manifold  112  to the muffler  114 . The muffler  114  is adapted to reduce exhaust noise downstream of each of the first pipe  116  and the second pipe  118 . 
     The exhaust system  102  also includes a number of downstream components coupled to the muffler  114 , such as a first auxiliary muffler  120  and a second auxiliary muffler  122 . The first auxiliary muffler  120  is adapted to receive the first exhaust stream “E 1 ” from the muffler  114 . The second auxiliary muffler  122  is adapted to receive the second exhaust stream “E 2 ” from the muffler  114 . Additionally, the exhaust system  102  can include one or more aftertreatment components/systems (not shown), such as a Diesel Particulate Filter (DPF) unit, a Diesel Oxidation Catalyst (DOC) unit, a Diesel Exhaust Fluid (DEF) unit, a Selective Catalytic Reduction (SCR) unit, a tailpipe, or other components based on application requirements. 
     Referring to  FIG. 2A , an exploded perspective view of the muffler  114  is illustrated. The muffler  114  includes a first casing  202  and a second casing  204 . In the illustrated embodiment, each of the first casing  202  and the second casing  204  has a substantially U-shaped configuration. In other embodiments, one or more of the first casing  202  and the second casing  204  can have any other configuration, such as a semi-circular configuration, a curved configuration, a stepped configuration, or other configuration based on application requirements. Each of the first casing  202  and the second casing  204  can be manufactured using any process, such as stamping, forging, casting, additive manufacturing, or other manufacturing process based on application requirements. 
     The muffler  114  also includes a first plate  206  and a second plate  208 . In the illustrated embodiment, each of the first plate  206  and the second plate  208  has a substantially flat and trapezoidal configuration. In other embodiments, one or more of the first plate  206  and the second plate  208  can have any other configuration, such as a bent configuration, an angled configuration, a stepped configuration, a circular configuration, an elliptical configuration, a rectangular configuration, or other configuration based on application requirements. Each of the first plate  206  and the second plate  208  can be manufactured using any process, such as stamping, forging, casting, additive manufacturing, or other manufacturing process based on application requirements. Each of the first casing  202 , the second casing  204 , the first plate  206 , and the second plate  208  is coupled to one other to form a housing  210  (shown in  FIG. 2B ) of the muffler  114  and will be explained in more detail later. Each of the first casing  202 , the second casing  204 , the first plate  206 , and the second plate  208  can be coupled to one other using any coupling process, such as welding, bolting, riveting, or other coupling process. 
     The muffler  114  further includes a first inner section  212  and a second inner section  214 . The second inner section  214  has a configuration substantially similar to a configuration of the first inner section  212 . Each of the first inner section  212  and the second inner section  214  has a substantially curved and X-shaped configuration. In the illustrated embodiment, each of the first inner section  212  and the second inner section  214  is manufactured by stamping process, rather than by a traditional casting method. In traditional cross-pipe muffler applications, the cast part was die-locked, which prevented the muffler pipes from being stamped. One of the issues solved by the present disclosure is that the present disclosure allows the muffler pipes to be stamped as two halves (i.e. first inner section  212  and second inner section  214 ) and later assembled. That said, it is possible that in other embodiments, each of the first inner section  212  and the second inner section  214  can be manufactured using any other process, such as forging, additive manufacturing, or other manufacturing process based on application requirements. 
     Each of the first inner section  212  and the second inner section  214  is coupled to one other to form a first tube  216  (shown in  FIG. 2B ) and a second tube  218  (shown in  FIG. 2B ) of the muffler  114 . Each of the first inner section  212  and the second inner section  214  can be coupled to one other using any coupling process, such as welding, bolting, riveting, or other coupling process. In one example, the two sections  212 ,  214  can be connected by a continuous relief  245  (shown best in  FIG. 2G, 2H ) that traverses the outside surface of the tubes  216 ,  218  and joins the two tubes  216 ,  218  together. As shown in  FIG. 2G, 2H , the use of multiple types of welds can be used to weld the two tubes  216 ,  218 . For example, the use of a central “clam shell joint”  250  can be used across a portion of the tubes  216 ,  218  and use of an overlapping or “shoe box joint”  252  can be used at the outboard edges. The outboard edges can be located on both sides of the clam shell joint. 
     Referring to  FIGS. 2B and 2C , different perspective views of the muffler  114  in an assembled position are illustrated. In the illustrated embodiment, the muffler  114  has a substantially elongated and trapezoidal configuration. In other embodiments, the muffler  114  can have any other configurations, such as circular, rectangular, or other configuration based on application requirements. The muffler  114  includes the housing  210 . The housing  210  is adapted to at least partially enclose the first inner section  212  and the second inner section  214  of the muffler  114  therein. The housing  210  includes a first end  220  and a second end  222 . The second end  222  is disposed opposite to the first end  220 . The housing  210  has a substantially hollow configuration and defines a first longitudinal axis A-A′ and a second longitudinal axis B-B′ of the muffler  114 . The first longitudinal axis A-A′ and the second longitudinal axis B-B′ are parallel to and spaced apart from each other. Also, each of the first longitudinal axis A-A′ and the second longitudinal axis B-B′ extends between the first end  220  and the second end  222  of the housing  210 . 
     The housing  210  includes the first plate  206  and the second plate  208 . The second plate  208  is spaced apart from the first plate  206  along the first longitudinal axis A-A′ and the second longitudinal axis B-B′. More specifically, the first plate  206  is disposed on the first end  220  of the housing  210  and the second plate  208  is disposed on the second end  222  of the housing  210 . In the illustrated embodiment, the first plate  206  and the second plate  208  are disposed parallel to one another and perpendicular to the first longitudinal axis A-A′ and the second longitudinal axis B-B′. In other embodiments, one or more of the first plate  206  and the second plate  208  can be inclined relative to the first longitudinal axis A-A′ and the second longitudinal axis B-B′. The housing  210  also includes the first casing  202  and the second casing  204 . Each of the first casing  202  and the second casing  204  extends between the first plate  206  and the second plate  208 . Each of the first casing  202  and the second casing  204  is adapted to at least partly enclose the first tube  216  and the second tube  218 . 
     The muffler  114  will now be explained with combined reference to  FIGS. 2D to 2G . The muffler  114  includes the first tube  216 . The first tube  216  is adapted to be fluidly coupled to the first pipe  116 . The first tube  216  includes a first inlet portion  224 . The first inlet portion  224  is disposed within an aperture  258  (shown in  FIG. 2A ) provided on the first plate  206 . The first inlet portion  224  defines a first inlet  226  of the first tube  216 . The first inlet portion  224  is adapted to be fluidly coupled to the first pipe  116 . Accordingly, the first tube  216  is adapted to receive the first exhaust stream “E 1 ” from the first pipe  116  into the first tube  216  via the first inlet  226  of the first inlet portion  224 . 
     In the illustrated embodiment, the first inlet portion  224  has a substantially straight configuration. In other embodiments, the first inlet portion  224  can have any other configuration, such as a curved configuration or an angled configuration. The first inlet portion  224  is disposed along a first axial plane “P 1 ”. In the illustrated embodiment, the first axial plane “P 1 ” is disposed along the first longitudinal axis A-A′. As such, in the illustrated embodiment, the first axial plane “P 1 ” is substantially parallel to the first longitudinal axis A-A′. In other embodiments, the first axial plane “P 1 ” can be inclined relative to the first longitudinal axis A-A′. Also, in other embodiments, the first axial plane “P 1 ” can be spaced apart from the first longitudinal axis A-A′. 
     The first tube  216  also includes a first outlet portion  228 . The first outlet portion  228  is disposed within an aperture  260  (shown in  FIG. 2A ) provided on the second plate  208 . The first outlet portion  228  defines a first outlet  230  of the first tube  216 . The first outlet portion  228  is adapted to be fluidly coupled to the downstream component, such as the first auxiliary muffler  120 , or can be open to atmosphere. Accordingly, the first tube  216  is adapted to release the first exhaust stream “E 1 ” from the first tube  216  into the first auxiliary muffler  120  or atmosphere via the first outlet  230  of the first outlet portion  228 . In the illustrated embodiment, the first outlet portion  228  has a substantially straight configuration. In other embodiments, the first outlet portion  228  can have any other configuration, such as a curved configuration, an angled configuration, or other configuration based on application requirements. 
     The first outlet portion  228  is disposed along a second axial plane “P 2 ”. In the illustrated embodiment, the second axial plane “P 2 ” is disposed along the second longitudinal axis B-B′. As such, in the illustrated embodiment, the second axial plane “P 2 ” is substantially parallel to the second longitudinal axis B-B′ and the first axial plane “P 1 ”. In other embodiments, the second axial plane “P 2 ” can be inclined relative to the second longitudinal axis B-B′. Also, in other embodiments, the second axial plane “P 2 ” can be spaced apart from the second longitudinal axis B-B′. Additionally, in the illustrated embodiment, the second axial plane “P 2 ” is vertically spaced from the first axial plane “P 1 ” by a distance “D 1 ”. In other embodiments, the second axial plane “P 2 ” and the first axial plane “P 1 ” can be coplanar, based on application requirements. 
     The first tube  216  further includes a first intermediate portion  232 . The first intermediate portion  232  extends from the first inlet portion  224  to the first outlet portion  228 . As such, the first intermediate portion  232  is fluidly coupled to the first inlet portion  224  and the first outlet portion  228 . The first intermediate portion  232  is adapted to allow flow of the first exhaust stream “E 1 ” from the first inlet portion  224  to the first outlet portion  228 . In the illustrated embodiment, the first intermediate portion  232  has a substantially curved configuration. More specifically, the first intermediate portion  232  extends away from the first inlet portion  224 , such that the first intermediate portion  232  bends perpendicularly relative to the first axial plane “P 1 ′ and the first longitudinal axis A-A′, and also laterally relative to the first axial plane “P 1 ′ and the first longitudinal axis A-A′ in order to align with the second longitudinal axis B-B′. Further, the first intermediate portion  232  bends toward the second longitudinal axis B-B′ and the second axial plane “P 2 ” in order to align with the first outlet portion  228 . Accordingly, the first intermediate portion  232  extends between the first axial plane “P 1 ” and the second axial plane “P 2 ” vertically spaced by the distance “D 1 ”. In other embodiments, the first intermediate portion  232  can have any other configuration, such as an angled configuration, a straight configuration, or other configuration based on application requirements. 
     The muffler  114  also includes the second tube  218 . The second tube  218  is adapted to be fluidly coupled to the second pipe  118 . The second tube  218  includes a second inlet portion  234 . The second inlet portion  234  is disposed within an aperture  262  (shown in  FIG. 2A ) provided on the second plate  208 . The second inlet portion  234  defines a second inlet  236  of the second tube  218 . The second inlet portion  234  is adapted to be coupled to the second pipe  118 . Accordingly, the second tube  218  is adapted to receive the second exhaust stream “E 2 ” from the second pipe  118  into the second tube  218  via the second inlet  236  of the second inlet portion  234 . In the illustrated embodiment, the second inlet portion  234  has a substantially straight configuration. In other embodiments, the second inlet portion  234  can have any other configuration, such as a curved configuration, an angled configuration, or other configuration based on application requirements. The second inlet portion  234  is disposed along a third axial plane “P 3 ”. In the illustrated embodiment, the third axial plane “P 3 ” is disposed along the first longitudinal axis A-A′. Accordingly, the second inlet portion  234  is spaced apart from the first inlet portion  224  along the first longitudinal axis A-A′. Also, in the illustrated embodiment, the third axial plane “P 3 ” is substantially parallel to the first longitudinal axis A-A′. In other embodiments, the third axial plane “P 3 ” can be inclined relative to the first longitudinal axis A-A′. Also, in other embodiments, the third axial plane “P 3 ” can be spaced apart from the first longitudinal axis A-A′. 
     In the illustrated embodiment, the third axial plane “P 3 ” and the first axial plane “P 1 ” are coplanar. Accordingly, the third axial plane “P 3 ” is vertically spaced from the second axial plane “P 2 ” by the distance “D 1 ”. In other embodiments, the third axial plane “P 3 ” can be spaced apart from the first axial plane “P 1 ”. Also, in the illustrated embodiment, the third axial plane “P 3 ” is parallel to each of the first axial plane “P 1 ” and the second axial plane “P 2 ”. In other embodiments, the third axial plane “P 3 ” can be inclined relative to one or more of the first axial plane “P 1 ” and the second axial plane “P 2 ”. 
     The second tube  218  also includes a second outlet portion  238 . The second outlet portion  238  is disposed within an aperture  264  (shown in  FIG. 2A ) provided on the first plate  206 . The second outlet portion  238  defines a second outlet  240  of the second tube  218 . The second outlet portion  238  is adapted to be fluidly coupled to the downstream component, such as the second auxiliary muffler  122 , or can be open to atmosphere. Accordingly, the second tube  218  is adapted to release the second exhaust stream “E 2 ” from the second tube  218  into the second auxiliary muffler  122  or atmosphere via the second outlet  240  of the second outlet portion  238 . In the illustrated embodiment, the second outlet portion  238  has a substantially straight configuration. In other embodiments, the second outlet portion  238  can have any other configuration, such as a curved configuration, an angled configuration, or other configuration based on application requirements. 
     The second outlet portion  238  is disposed along a fourth axial plane “P 4 ”. In the illustrated embodiment, the fourth axial plane “P 4 ” is disposed along the second longitudinal axis B-B′. Accordingly, the second outlet portion  238  is spaced apart from the first outlet portion  228  along the second longitudinal axis B-B′. Also, in the illustrated embodiment, the fourth axial plane “P 4 ” is substantially parallel to the second longitudinal axis B-B′. In other embodiments, the fourth axial plane “P 4 ” can be inclined relative to the second longitudinal axis B-B′. Also, in other embodiments, the fourth axial plane “P 4 ” can be disposed spaced apart from the second longitudinal axis B-B′. Additionally, in the illustrated embodiment, the fourth axial plane “P 4 ” is vertically spaced from the third axial plane “P 3 ” by a distance “D 2 ”. In the illustrated embodiment, the distance “D 2 ” is approximately equal to the distance “D 1 ” between the first axial plane “P 1 ” and the second axial plane “P 2 ”. In other embodiments, the fourth axial plane “P 4 ” and the third axial plane “P 3 ” can be coplanar, based on application requirements. 
     In the illustrated embodiment, the fourth axial plane “P 4 ” and the second axial plane “P 2 ” are coplanar. Accordingly, the fourth axial plane “P 4 ” is vertically spaced from the first axial plane “P 1 ” by the distance “D 1 ”. In other embodiments, the fourth axial plane “P 4 ” can be spaced apart from the second axial plane “P 2 ”. Also, in the illustrated embodiment, the fourth axial plane “P 4 ” is parallel to each of the first axial plane “P 1 ”, the second axial plane “P 2 ”, and the third axial plane “P 3 ”. In other embodiments, the fourth axial plane “P 4 ” can be inclined relative to one or more of the first axial plane “P 1 ”, the second axial plane “P 2 ”, and the third axial plane “P 3 ”. 
     The second tube  218  further includes a second intermediate portion  242 . The second intermediate portion  242  extends from the second inlet portion  234  to the second outlet portion  238 . As such, the second intermediate portion  242  is fluidly coupled to the second inlet portion  234  and the second outlet portion  238 . The second intermediate portion  242  is adapted to allow flow of the second exhaust stream “E 2 ” from the second inlet portion  234  to the second outlet portion  238 . In the illustrated embodiment, the second intermediate portion  242  has a substantially curved configuration. More specifically, the second intermediate portion  242  extends away from the second inlet portion  234 , such that the second intermediate portion  242  bends perpendicularly relative to the third axial plane “P 3 ′ and the first longitudinal axis A-A′, and also laterally relative to the third axial plane “P 3 ′ and the first longitudinal axis A-A′ in order to align with the second longitudinal axis B-B′. Further, the second intermediate portion  242  bends toward the second longitudinal axis B-B′ and the fourth axial plane “P 4 ” in order to align with the second outlet portion  238 . Accordingly, the second intermediate portion  242  extends between the third axial plane “P 3 ” and the fourth axial plane “P 4 ” vertically spaced by the distance “D 2 ”. In other embodiments, the second intermediate portion  242  can have any other configuration, such as an angled configuration, a straight configuration, or other configuration based on application requirements. 
     Additionally, the first intermediate portion  232  and the second intermediate portion  242  are disposed in manner such that the first intermediate portion  232  and the second intermediate portion  242  cross each other. Also, the first intermediate portion  232  and the second intermediate portion  242  are at least partially stacked on each other defining a substantially twisted X-shaped configuration of the first intermediate portion  232  and the second intermediate portion  242 . As such, crossing and stacking of the first intermediate portion  232  and the second intermediate portion  242  provides a substantially separate flow path for each of the first exhaust stream “E 1 ” and the second exhaust stream “E 2 ” flowing in substantially opposite direction without complete interaction and mixing of the first exhaust stream “E 1 ” with the second exhaust stream “E 2 ” within the muffler  114 . Further, the first intermediate portion  232  and the second intermediate portion  242  are fluidly coupled to each other. Accordingly, a common chamber  244  is defined within each of the first intermediate portion  232  and the second intermediate portion  242 . The common chamber  244  is adapted to provide at least partial interaction and mixing of the first exhaust stream “E 1 ” with the second exhaust stream “E 2 ”. 
       FIGS. 2H-J  depict structural improvements to the muffler due to issues caused by joining the two sections  212 ,  214  by the welded continuous relief  245  that traverses the outside surface of the tubes  216 ,  218  and joins the two tubes  216 ,  218  together. The addition of the continuous relief  245  causes flow mixing to have a negative effect on mixing performance. In other words, adding the continuous relief  245  could cause the two exhaust streams, E 1  and E 2  to collide, which negatively impacts mixing performance. Thus, the structural changes depicted in  FIGS. 2H-J  change the exhaust stream E 1 , E 2  path flows to minimize collision of flow in the common chamber  244 , thus increasing mixing performance. 
       FIG. 2H  depicts a side view of the muffler  114  and illustrates inlet ramps  254  on each of the tubes  216 ,  218  of the muffler  114 . The inlet ramps  254  can be positioned to deflect exhaust stream E 1 , E 2  that enters each tube  216 ,  218  away from the center of common chamber  244 . In other words, the exhaust stream E 1 , E 2  of each tube  216 ,  218  is deflected toward the outer peripheral surface  256  of each tube  214 ,  216  thereby helping improve or reduce collisions of the two exhaust streams E 1 , E 2  from the tubes  214 ,  216 . 
       FIG. 2I  depicts a side view of the muffler  114  and illustrates an outer peripheral surface  266  in the shape of a ramp that defines the shape of the tubes  216 ,  218  of the muffler  114 . As illustrated, each tube  216 ,  218  has ramp that defines a changing, non-uniform cross section as it transitions away from the common chamber  244  toward each outlet  228 ,  238 . While it should be recognized the outer peripheral surface  266  is shown on the outlet side of the common chamber  244 , it could also be positioned on the intel side. Each tube  216 ,  218  starts at the inlets  224 ,  234  and outlets  228 ,  238  as a uniform cylindrical aperture and transitions along the peripheral surfaces  256 ,  266 , which causes the tubes  216 ,  218  as it approaches the common chamber  244  to have a changing, non-uniform cross-sectional area as designated by arrows  268  (showing the outlet side). In other words, the tubes  216 ,  218  can be an elliptical shape at the common chamber  244  and can transition to a cylinder shape at the inlets  224 ,  234  and outlets  228 ,  238 . As exhaust stream flow to and from the common chamber  244 , the changing, non-uniform cross-section  268  defined by the outer peripheral surfaces  256 ,  266  reduces flow noise at because the elliptical shape allows exhaust gases E 1 , E 2  to flow near the outer peripheral surfaces  256 ,  266  and away from the center of the common chamber  244 . 
       FIG. 2J  shows the inlets and outlets at each tube  216 ,  218  end of the muffler  114  as depicted through cross-section A-A and B-B of  FIG. 3 . In end view A-A, E 1  is illustrative of exhaust stream exiting the muffler and E 2  is illustrative of exhaust stream entering the muffler. In end view B-B, E 2  is illustrative of exhaust stream exiting the muffler and E 1  is illustrative of exhaust stream entering the muffler. As illustrated, the area A 1  near the inlet  224  is less than the area A 4  near the outlet  238  through cross section B-B. Similarly, the area A 2  near the inlet  234  is less than the area A 3  near the outlet  228  through cross section A-A. Additionally, the centroid of each area can be offset from the centerline  270 , which allows the exhaust streams E 1 , E 2  to be redirected away from the center of the common chamber  244 , thereby helping improve or reduce collisions of the two exhaust streams E 1 , E 2  from the tubes  216 ,  218 . 
     Referring to  FIG. 3 , during operation of the exhaust system  102 , the muffler  114  receives the first exhaust stream “E 1 ” from the first pipe  116 , as shown by an arrow  302 . The first exhaust stream “E 1 ” enters the first tube  216  via the first inlet  226  of the first inlet portion  224 , as shown by the arrow  302 . The first exhaust stream “E 1 ” then flows through the first intermediate portion  232  and the common chamber  244 , as shown by an arrow  304 . Further, the first exhaust stream “E 1 ” flows through the first outlet portion  228  and out of the muffler  114  via the first outlet  230  of the first outlet portion  228 , as shown by an arrow  306 . Also, the muffler  114  receives the second exhaust stream “E 2 ” from the second pipe  118 , as shown by an arrow  308 . The second exhaust stream “E 2 ” enters the second tube  218  via the second inlet  236  of the second inlet portion  234 , as shown by the arrow  308 . The second exhaust stream “E 2 ” then flows through the second intermediate portion  242  and the common chamber  244 , as shown by an arrow  310 . Further, the second exhaust stream “E 2 ” flows through the second outlet portion  238  and out of the muffler  114  via the second outlet  240  of the second outlet portion  238 , as shown by an arrow  312 . 
     As the first exhaust stream “E 1 ” and the second exhaust stream “E 2 ” cross each other in the common chamber  244 , the first intermediate portion  232  and the second intermediate portion  242  provide substantially separate flow paths for the first exhaust stream “E 1 ” and the second exhaust stream “E 2 ”. As such, due to flow of the first exhaust stream “E 1 ” and the second exhaust stream “E 2 ” in different axial planes complete interaction and mixing of the first exhaust stream “E 1 ” and the second exhaust stream “E 2 ” is limited, in turn, reducing drag and backpressure within the muffler  114 . Also, as the first exhaust stream “E 1 ” and the second exhaust stream “E 2 ” cross each other in the common chamber  244 , the common chamber  244  provides limited interaction and mixing of the first exhaust stream “E 1 ” and the second exhaust stream “E 2 ”, in turn, cancelling half engine order noise generated in each of the first pipe  116  and the second pipe  118  of the exhaust system  102  and reducing fluid noise within the muffler  114 . As a result, an overall exhaust noise is reduced downstream of the muffler  114  relative to a conventional muffler having substantial interaction and mixing of different exhaust streams therein. 
     The muffler  114  provides a simple, efficient, and cost-effective method of reducing exhaust noise downstream of each of the first pipe  116  and the second pipe  118 . The muffler  114  includes the first tube  216  and the second tube  218  providing substantially separate flow path for each of the first exhaust stream “E 1 ” and the second exhaust stream “E 2 ”. As such, direct collision between the first exhaust stream “E 1 ” and the second exhaust stream “E 2 ” is reduced, in turn, reducing drag and backpressure within the muffler  114 . More specifically, the first intermediate portion  232  and the second intermediate portion  242  provide crossing of the first exhaust stream “E 1 ” and the second exhaust stream “E 2 ” via the common chamber  244  without direct collision of opposing flows of the first exhaust stream “E 1 ” and the second exhaust stream “E 2 ”. 
     Also, the curved configuration of each of the first intermediate portion  232  and the second intermediate portion  242  provides gradual change in flow direction of the first exhaust stream “E 1 ” and the second exhaust stream “E 2 ”, in turn, reducing drag and backpressure within the muffler  114 . Additionally, the common chamber  244  provides limited and controlled interaction between portions of the first exhaust stream “E 1 ” and the second exhaust stream “E 2 ”, in turn, cancelling half order engine noise and reducing the overall exhaust noise. The muffler  114  can be manufactured using any process, such as stamping, casting, or any other process, in turn, providing ease of manufacturing and reducing costs. The muffler  114  can be retrofitted in any exhaust system, in turn, providing improved usability, flexibility, and compatibility. 
     While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments can be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.