Abstract:
The present disclosure is directed toward an assembly for an exhaust system. The assembly includes a first exhaust system component having a first mating structure and a second exhaust system component having a second mating structure. The second mating structure is mated with the first mating structure in a manner that allows the second mating structure to move along an axis relative to the first mating structure. Additionally, a first seal is disposed in the interface created between the first exhaust system component and the second exhaust system component.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to joints between exhaust system components and, more particularly, to sealing joints between exhaust system components. 
       BACKGROUND 
       [0002]    An exhaust system for a power source, such as an engine, may include an exhaust joint between sections of the exhaust system. For example, an exhaust system may include an exhaust manifold with an exhaust joint between sections of the exhaust manifold. The exhaust joint between sections of the exhaust system may contain an exhaust seal. The exhaust seal may fill any space in the exhaust joint in order to prevent exhaust leakage. 
         [0003]    A conventional exhaust joint and an exhaust seal, such as a hardened sealant or simple gasket, may not be a practical solution for all applications, especially in high temperature exhaust applications where substantial thermal expansion occurs. Conventional exhaust joints may somewhat constrain relative movement, that is, the components connected by the joint may be unable to freely expand in response to temperature increases. This inability of exhaust components to freely expand when their temperature increases may cause thermal stresses to build up and may eventually lead to exhaust component stress failure. Stresses due to thermal expansion may cause cracking in the exhaust manifold, exhaust joint, or at any point in the exhaust system. Further, stress arising from axial misalignment, cyclic vibration, and mechanical loading may also contribute to failure and crack formation. 
         [0004]    U.S. Pat. No. 4,863,200 (the &#39;200 patent) issued to Brandener on Sep. 5, 1989 discloses an exhaust joint comprising a pivot point that provides flexibility between the two exhaust components connected by the joint. The exhaust joint disclosed in the &#39;200 patent employs a fixed sheet metal flange surrounded by a housing that encloses the joint. The housing provides the pivot point of the joint. Further, the housing is welded to one exhaust component and then crimped together around the flange. Two annular metal knit gaskets positioned on opposite sides of the flange provide a seal between the two exhaust system components. 
         [0005]    Although the exhaust joint of the &#39;200 patent may have a pivot point that provides flexibility, certain disadvantages persist. The disclosed solution may not accommodate axial misalignment, particularly substantial axial misalignment resulting from thermal expansion. Additionally, since the gaskets are contained inside a housing that is welded and crimped together, maintenance and repair of the joint disclosed in the &#39;200 patent may be difficult, time consuming, and expensive. 
         [0006]    The disclosed exhaust joint is directed to overcoming one or more of the problems set forth above. 
       SUMMARY 
       [0007]    In one aspect, the present disclosure is directed toward an assembly for an exhaust system. The assembly includes a first exhaust system component having a first mating structure and a second exhaust system component having a second mating structure. The second mating structure is mated with the first mating structure in a manner that allows the second mating structure to move along an axis relative to the first mating structure. Additionally, a first seal is disposed in the interface created between the first exhaust system component and the second exhaust system component. 
         [0008]    In another aspect, the present disclosure is directed to a method for sealing a portion of an exhaust system. The method includes mating a first structure of a first exhaust system component to a second mating structure of a second exhaust system component, thereby creating an exhaust system joint between the first mating structure and the second mating structure. Further, the method includes impeding leakage of exhaust gas from the exhaust system joint with a first seal disposed in the interface between the first mating structure and the second mating structure. Still further, the method also includes impeding leakage of exhaust gas from the exhaust system joint with a second seal disposed in the interface between the first mating structure and the second mating structure. Finally, the method includes impeding leakage of exhaust gas from the exhaust system joint with sealant disposed between the first seal and the second seal. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a pictorial representation of an exemplary power system; 
           [0010]      FIG. 2  is a pictorial representation of the exemplary exhaust manifold for a power system with an exemplary exhaust system joint; and 
           [0011]      FIG. 3  is a perspective view of the exemplary exhaust system joint. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    An exemplary embodiment of a power system  2 , is illustrated in  FIG. 1 . The power system  2  may include an engine  5 , such as, for example a diesel engine, a gasoline engine, a natural gas engine, or any other engine apparent to one skilled in the art. The power system may further include an exhaust manifold  10  with an exhaust system joint  15 , a turbine  20 , and a compressor  25 . Exhaust manifold  10  may be configured to direct exhaust from an engine to the turbine  20 . Turbine  20  may be mechanically connected to drive compressor  25  of an air intake system for the engine  5 . It is contemplated that turbine  20  may be omitted and compressor  25  may be driven by the engine  5  mechanically, hydraulically, electrically or in any other manner known in the art. Furthermore, compressor  25  may be omitted entirely. 
         [0013]      FIG. 2  illustrates a portion of an exhaust system  11  for a power system  2 . The portion of the exhaust system  11  shown in  FIG. 2  may include an exhaust assembly  12  formed by a first exhaust system component  30  connected by an exhaust system joint  15  to a second exhaust system component  35 . As shown in the embodiment of  FIG. 2 , exhaust assembly  12  of the exhaust system may be a portion of an exhaust manifold  10 , or alternatively, may be any other portion of the exhaust system. Exhaust system joint  15  may be a slip joint configured to compensate for axial  14  misalignment. The exhaust system joint  15  may also be configured to compensate for thermal expansion of exhaust system components  30 , 35 . 
         [0014]      FIG. 3  is a perspective cut away view of the exhaust system joint  15 . In the embodiment shown, the exhaust system joint  15  consists of a portion of the first exhaust system component  30  mated to a portion of the second exhaust system component  35 . First exhaust system component  30  and second exhaust system component  35  may be, for example, hollow tubular members with substantially circular cross sections. Thus, first exhaust system component  30  may include an interior cavity  31  for conduction of exhaust gasses, and second exhaust system component  35  may include an interior cavity  36  for conduction of exhaust gasses. Internal cavity  31  and internal cavity  36  may connect at exhaust joint  15 . It is contemplated that the first exhaust system component  30  and the second exhaust system component  35  may be formed using a sand casting method, an extrusion method, or any other method apparent to one skilled in the art. 
         [0015]    The first exhaust system component  30  may further include first mating structure  32 . Likewise, the second exhaust system component  35  may include a second mating structure  37 . The first mating structure  32  and the second mating structure  37  may include mating surfaces  33 , 38  that are substantially parallel to the axis  14 . The second mating structure may also include a recess  39 , and the first mating structure may be disposed, at least partially, into the recess  39 . Recess  39 , first mating structure  32 , second mating structure  37  may all have axes that are substantially parallel to the axis  14 . 
         [0016]    The position of first mating structure  32  and second mating structure  37  relative to each other may create an axial gap  45 . Axial gap  45  may shrink when the first exhaust system component  30  and the second exhaust system component  35  both expand axially  14  in opposite directions as a result of increasing temperature. Additionally, the size of axial gap  45  may depend on the initial position of each exhaust system component  30 , 35  in the axial  14  direction, which may vary due to manufacturing tolerances and other factors. 
         [0017]    At an interface  40  formed between the outside diameter of the first exhaust system component  30  and inside diameter of the second exhaust system component  35  of the embodiment shown in  FIG. 3 , a first seal  65  and a second seal  80  may each provide a barrier between the internal cavities  31 , 36  and the ambient environment  85 . The first seal  65  and the second seal  80  may be configured to substantially seal the interface  40 , thereby blocking fluid inside the internal cavities  31 , 36  from passing to the outside of exhaust system components  30 , 35  to the ambient environment  85 . The first seal  65  and/or the second seal  80  may be, for example, labyrinth seals. As used herein, a labyrinth seal is any seal that confronts a fluid with a long and arduous path that the fluid must traverse in order to escape past the seal. In one embodiment, the labyrinth seal may include a metallic ring that requires the fluid to traverse each of its windings in order to escape. 
         [0018]    The first seal  65  may be disposed in a substantially annular groove  60  and the second seal  80  may be disposed in a similar groove  75 . The grooves  60 , 75  may be features of first exhaust system component  30  and/or second exhaust system component  35 , or may be altogether omitted. The seals  65 , 80  and/or the grooves  60 , 75  may be saturated with a viscous sealant in order to further seal the exhaust joint  15 . 
         [0019]    Sealant  71  may be added to the exhaust joint  15 . For example, the sealant may be placed in a substantially annular channel  70 . It is contemplated that channel  70  may have various configurations, or may be omitted completely. In the embodiment shown in  FIG. 3 , the channel  70  may be disposed between a first seal  65  and a second seal  80 . However, the channel  70  could be disposed at any point on the interface  40  and between the first seal  65  and the second seal  80 . The sealant may consist largely of a particulate metal, a copper paste, a graphite powder, a carbon powder, or any other sealant used for its thermal expansion properties and apparent to one skilled in the art. The sealant may be added to exhaust joint  15  in various ways. In some embodiments, the sealant may be added into the channel  70  via a port  55  of a zerk fitting  50  with a grease gun or any other suitable means. 
         [0020]    The exhaust assembly  12  of the exhaust system is not limited to the configuration shown in  FIG. 2  and  FIG. 3 . For example, exhaust system components  30 , 35  may have different shapes than shown in  FIG. 2  and  FIG. 3 . Additionally, one or both of components  30 , 35  may form part of the exhaust system other than exhaust manifold  10 . Indeed, exhaust components  30 , 35  and exhaust joint  15  may form any part of an exhaust system. 
       INDUSTRIAL APPLICABILITY 
       [0021]    As described above, the exhaust joint  15  disclosed herein may be applied to any combustion type device, such as, for example, an engine, a furnace, or any other device known in the art where the flow of hot gasses may be directed away from the combustion device. The exhaust joint  15  may be a simple, inexpensive, and durable solution to accommodate thermal expansion, axial misalignment, vibrational loading, and mechanical loading. Additionally, the exhaust joint  15  may enable high temperature and high pressure fluids to be transported away from the combustion device while remaining sealed off from the ambient environment  85 . 
         [0022]    In the current embodiment, the combustion device may be an engine, such as a twelve cylinder diesel engine. Attached to the engine, the exhaust manifold  10  and the exhaust joint  15  may be configured to collect exhaust gases from the engine and transport the gases to a turbine  20 . The running engine may expel hot exhaust gasses from the engine under a pressure. As the gas is forced through the turbine  20 , the exhaust gas impinging on the blades (not shown) of the turbine  20  may cause the impeller (not shown) of the turbine  20  to rotate and rotate the mechanically connected impeller (not shown) of the compressor  25 . The combined inertia of the impellers of the turbine  20  and the compressor  25  may cause pressure to build in the exhaust manifold  10  and the exhaust joint  15  between the engine  5  and the turbine  20 . 
         [0023]    A pressure gradient between internal cavities  31 , 36  and the ambient environment  85  may cause a tendency for the exhaust gas to pass through the axial gap  45  into the interface  40 . If the exhaust gas does enter the interface  40 , it may encounter the first seal  65 . The pressure of the exhaust gas may cause the first seal  65  to press tightly against the wall of first groove  60  and thereby obstruct the flow of exhaust through the interface  40  to the ambient environment  85 . 
         [0024]    If the exhaust gas escapes past the first seal  65 , it may encounter the viscous sealant  71  disposed in channel  70 . Thus, the viscous sealant may further restrict the flow of fluid from internal cavities  31 , 36  to the ambient environment  85 . Since the sealant is composed in large part of metallic particles, the sealant may expand as temperatures increase. This may help the sealant maintain an effective seal in the interface  40  when exhaust system components  30 , 35  undergo thermal expansion and contraction. It is contemplated that the sealant may permeate the first seal  65  and the second seal  80  thereby increasing the effectiveness of the seals  65 , 80 . Exhaust gasses that push past the first seal  65  and the sealant  71  in channel  70  may encounter the second seal  80 . Second seal  80  may be disposed within annular groove  75 , and may seal the joint  15  in a similar fashion to that of the first seal  65 . 
         [0025]    During operation, the temperature of the engine  5 , exhaust manifold  10 , exhaust joint  15 , and turbine  20  may increase. Hot exhaust gas from the engine  5 , may transfer heat from combustion to the exhaust manifold  10 , exhaust joint  15 , and the turbine  20 . The addition of heat to these components may cause each component to expand. In particular, first exhaust system component  30  and second exhaust system component  35  may expand in both axial  14  and radial directions. Expansion of the first exhaust system component  30  in the axial  14  direction increases its length along the axis  14 . Likewise, expansion of the second exhaust system component  35  in the axial  14  direction increases its length along the axis  14  thereby reducing the axial gap  45 . It is contemplated that the axial gap  45  may be sized to accommodate the anticipated thermal expansion caused by a standard operating temperature of the engine  5 . 
         [0026]    Additionally, the exhaust system components  30 , 35  may also expand in a radial direction, perpendicular to the axis  14  as temperatures increase. Since the first mating structure  32  is in direct contact with the hot exhaust gasses, the first mating structure  32  may expand more than the second mating structure  37  that is in direct contact with the cooler ambient environment  85 . This difference in expansion may cause the interface  40  to constrict, thereby increasing the effectiveness of the seals  65 , 80  and further impeding flow of exhaust from the internal cavities  31 , 36  to the ambient environment  85 . 
         [0027]    Several advantages may be realized from the overall design disclosed herein. The disclosed configuration of exhaust joint  15  may allow substantial thermal expansion of the first exhaust system component  30  and the second exhaust system component  35  along their lengths without creating interference between exhaust system components  30 , 35 . Allowing exhaust system components  30 , 35  to freely expand into axial gap  45  when heated, may reduce the tendency to form cracks due to thermally induced stress. Moreover, a fluid tight seal is maintained during axial and radial thermal expansion. 
         [0028]    Another advantage of the design disclosed herein is the ability of the system to accommodate axial misalignment of exhaust system components  30 , 35 . Such axial misalignment may arise, for example, from variations due to manufacturing tolerances. The axial gap  45 , may absorb these variations in axial alignment. This ability to compensate for axial misalignment allows for the use of parts that deviate significantly from design dimensions, instead of scrapping them, thereby saving cost. 
         [0029]    Still another advantage of the design disclosed herein is the ease of maintenance. After the initial introduction of sealant  71 , during the assembly of exhaust joint  15 , exhaust joint  15  may occasionally be replenished with sealant by adding additional sealant through port  55  of the zerk fitting  50 . Adding sealant routinely may improve the effectiveness of the first seal  65  and the second seal  80 . 
         [0030]    It will be apparent to those skilled in the art that various modifications and variations can be made to the exhaust joint, without departing from the scope of the disclosure. Other embodiments of the disclosed joint will be apparent to those skilled in the art from consideration of the specification and practice disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.