Patent Publication Number: US-2022235793-A1

Title: Sheet metal turbine housing

Description:
TECHNICAL FIELD 
     The subject matter described herein relates generally to flow control systems, and more particularly, to turbine housings for use in turbocharger systems. 
     BACKGROUND 
     Turbocharger systems are frequently used to improve the efficiency of internal combustion engines, for example, to achieve fuel economy targets or other environmental goals. During operation, the turbine housing experiences thermal and mechanical stress, and as a result, is often the most expensive component of a turbocharger system due to its size, complexity and material. In some situations, the added financial cost in conjunction with the size, packaging, assembly, or installation constraints may be prohibitive. Additionally, introducing turbines into the exhaust gas flow can reduce the temperature of the exhaust gas and may reduce the effectiveness of downstream emissions control devices, such as a catalytic converter. Accordingly, it is desirable to provide a turbine housing having lower thermal inertia while also achieving other performance objectives and maintaining structural integrity. 
     BRIEF SUMMARY 
     Turbine housing assemblies and related fabrication methods are provided. An exemplary turbine housing assembly includes a bearing flange, a tongue member coupled to the bearing flange, a first sheet metal structure joined to the tongue member, the first sheet metal structure providing an inner contour of an inlet passage, and a second sheet metal structure including an inlet portion providing an outer contour of the inlet passage and a volute portion providing an outer contour of a volute in fluid communication with the inlet passage. The volute portion is joined to the tongue member to define the volute and the inlet portion of the second sheet metal structure is joined to the first sheet metal structure to define the inlet passage. 
     In another embodiment, a turbine housing assembly includes a bearing flange, a tongue member, an inlet sheet metal structure having an end coupled to the tongue member, an inner sheet metal shell including an inlet portion and a volute portion, and an outer containment sheet metal shell surrounding at least a portion of the volute portion. The outer containment sheet metal shell is coupled to the bearing flange and spaced apart from the inner sheet metal shell, the inlet portion of the inner sheet metal shell is coupled to the inlet sheet metal structure to cooperatively define an inlet passage, and the volute portion of the inner sheet metal shell is coupled to the tongue member and the bearing flange to cooperatively define a volute in fluid communication with the inlet passage. 
     In another embodiment, a method of fabricating a turbine housing is provided. The method involves forming a first inlet portion from a first sheet metal structure, forming a second inlet portion and a volute portion from a second sheet metal structure, forming a first joint between an end of the first inlet portion and a tongue member joined to a bearing flange, forming a second joint between the first inlet portion and the second inlet portion to define an inlet passage, and forming a third joint between the volute portion and the tongue member, wherein the volute portion and the tongue member are cooperatively configured to define a volute in fluid communication with the inlet passage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the subject matter will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and: 
         FIG. 1  is an exploded view of a turbine housing assembly in one or more exemplary embodiments; 
         FIG. 2  is a perspective view of the turbine housing assembly of  FIG. 1 ; 
         FIG. 3  is a perspective view of a tongue member of the turbine housing assembly in  FIGS. 1-2 ; 
         FIG. 4  is a perspective view of an inlet sheet metal structure of the turbine housing assembly in  FIGS. 1-2 ; 
         FIG. 5  is a perspective view of an inner sheet metal shell of the turbine housing assembly in  FIGS. 1-2 ; 
         FIG. 6  is a perspective view of an outer sheet metal shell of the turbine housing assembly in  FIGS. 1-2 ; 
         FIG. 7  is a cross-sectional view of the turbine housing assembly of  FIGS. 1-2  along the line  7 - 7  in  FIG. 2  in one or more exemplary embodiments; 
         FIG. 8  is a perspective view of a flange including an integrated tongue member suitable for use in a turbine housing assembly in one or more exemplary embodiments; 
         FIG. 9  is a perspective view of the flange of  FIG. 8  assembled with the inlet sheet metal structure of  FIG. 4  in one or more exemplary embodiments; 
         FIG. 10  is a perspective view of the inner sheet metal shell of  FIG. 5  assembled with the flange and the inlet sheet metal structure after assembling the flange with the inlet sheet metal structure as depicted in  FIG. 9  in one or more exemplary embodiments; 
         FIG. 11  is a plan view of the outer sheet metal shell of  FIG. 6  assembled with the flange after assembling the inner sheet metal shell with the flange and the inlet sheet metal structure as depicted in  FIG. 10  in one or more exemplary embodiments; 
         FIG. 12  is a perspective view of the tongue member of  FIG. 3  assembled with the inlet sheet metal structure of  FIG. 4  in one or more exemplary embodiments; and 
         FIG. 13  is a perspective view of the inner sheet metal shell of  FIG. 5  assembled with the tongue member and the inlet sheet metal structure after assembling the tongue member with the inlet sheet metal structure as depicted in  FIG. 12  in one or more exemplary embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the subject matter described herein relate to turbines or turbocharger systems that include a turbine stage having a multilayer sheet metal housing made up of standardizable subcomponents to provide flexibility and extensibility to accommodate different applications or installations. As described in greater detail below, the turbine housing assembly includes an inlet sheet metal piece that is joined to a tongue member and a flange having an opening for receiving a turbine wheel (alternatively referred to herein as a bearing flange or center housing flange) to define an inner contour of an inlet. An inner sheet metal shell that includes an inlet portion that defines an outer contour of the inlet and a volute portion defining an outer contour of a volute is joined to the bearing flange, the tongue member and the inlet sheet metal piece to define the inlet in fluid communication with the volute. An outer containment sheet metal shell surrounds the volute portion of the inner sheet metal shell and is joined to the bearing flange. The outer containment sheet metal shell is separated from the inner sheet metal shell by an air gap which may be occupied by a layer of thermal insulation or other thermal insulating material to minimize heat loss from the volute (which conducts relatively hotter exhaust gases) into the environment between the inner sheet metal shell and the containment sheet metal shell, thereby maintaining a relatively lower temperature for the containment shell and increasing efficiency of the turbine. 
     Embodiments of the turbine housing assemblies described herein may be designed for and utilized with any sort of vehicle, such as, for example, heavy-duty or performance automotive vehicles to light-duty automotive vehicles. In this regard, a turbine wheel disposed within a turbine housing assembly may be mounted or otherwise coupled to a compressor wheel (or impeller) via a common rotary shaft to function as a turbocharger. The turbine inlet may be configured to receive exhaust gas flow from the cylinders of an internal combustion engine (e.g., from the exhaust manifold), which subsequently exits or bypasses the turbine wheel to a catalytic converter or other downstream emissions arrangement (e.g., via ducting or another conduit). In practice, the catalytic converter or other emissions control device may have an efficacy that is influenced by the temperature of the exhaust gas at its inlet, and accordingly, it is desirable to minimize the thermal inertia associated with the turbine housing assembly downstream of the exhaust manifold(s) of the engine to facilitate a higher exhaust gas temperature at the inlet of the emissions arrangement. 
     As used herein, the term “axial” refers to a direction that is generally parallel to or coincident with an axis of rotation, axis of symmetry, or centerline of a component or components. For example, in a cylinder or disc with a centerline and generally circular ends or opposing faces, the “axial” direction may refer to the direction that generally extends in parallel to the centerline between the opposite ends or faces. In certain instances, the term “axial” may be utilized with respect to components that are not cylindrical (or otherwise radially symmetric). For example, the “axial” direction for a rectangular housing containing a rotating shaft may be viewed as a direction that is generally parallel to or coincident with the rotational axis of the shaft. Furthermore, the term “radially” as used herein may refer to a direction or a relationship of components with respect to a line extending outward from a shared centerline, axis, or similar reference, for example in a plane of a cylinder or disc that is perpendicular to the centerline or axis. In certain instances, components may be viewed as “radially” aligned even though one or both of the components may not be cylindrical (or otherwise radially symmetric). Furthermore, the terms “axial” and “radial” (and any derivatives) may encompass directional relationships that are other than precisely aligned with (e.g., oblique to) the true axial and radial dimensions, provided the relationship is predominately in the respective nominal axial or radial direction. 
     Additionally, for purposes of explanation, the term “inner” may be utilized herein to refer to elements, features, or surfaces that are relatively closer to or generally face, in the axial direction, the turbine wheel or rotating assembly that the turbine housing is mounted or otherwise joined to, while the term “outer” may be utilized herein to refer to elements, features, or surfaces that are relatively farther from or generally face away from the turbine wheel or rotating assembly in the axial direction. The term “interior” may be utilized herein to refer to elements, features, or surfaces that are relatively closer to the axis of rotation associated with the turbine wheel or generally face radially inward, while the term “peripheral” may be utilized herein to refer to elements, features, or surfaces that are relatively farther from or generally face away from axis of rotation. It should also be understood that the drawings are merely illustrative and may not be drawn to scale. In addition, while the figures shown herein depict an example with certain arrangements of elements, additional intervening elements, devices, features, or components may be present in an actual embodiment. 
       FIGS. 1-7  depict an exemplary embodiment of a turbine housing assembly  100  suitable for use in a turbocharger system. The turbine housing assembly  100  includes a tongue member  102  and sheet metal structures  104 ,  106  that are cooperatively configured to define boundaries of a radial inlet  200  tangential to a volute  700  ( FIG. 7 ). The tongue member  102  and sheet metal structures  104 ,  106  are coupled or joined to a bearing flange  108  for mounting the turbine housing assembly  100  to a rotating assembly. In this regard, the bearing flange  108  includes a substantially circular interior opening  109  configured to receive a turbine wheel to be disposed within the volute  700  defined by the sheet metal structure  106 . The inner surface of a volute portion  110  of the sheet metal structure  106  that faces the turbine wheel in the axial direction is contoured to define the outer contour of the volute  700 , which is a voided region providing a scroll-shaped exhaust gas passageway. For purposes of explanation, the sheet metal structure  106  may alternatively be referred to herein as the inner sheet metal shell, the volute sheet metal shell, or variants thereof. An inner surface of the inlet portion  112  of the inner sheet metal shell  106  is contoured to define the outer contour of the inlet  200  in fluid communication with the volute  700  defined by the volute portion  110 , and the surface  114  of the sheet metal structure  104  that faces the inlet portion  112  of the inner sheet metal shell  106  is contoured and configured in concert with the inlet portion  112  to define the inlet  200 . Stated another way, the inlet portion  112  of the inner sheet metal shell  106  cooperates with the sheet metal structure  104  to define the inlet passage  200 , which is fluidly coupled to or in fluid communication with the volute  700 . For purposes of explanation, the sheet metal structure  104  may alternatively be referred to herein as the inlet sheet metal structure  104 . 
     With reference to  FIG. 3 , the tongue member  102  is physically distinct from the sheet metal structures  104 ,  106  and includes a protruding divider portion  130  that extends axially from the tongue member  102 . The protruding divider portion  130  is disposed radially between the inlet sheet metal structure  104  and the volute portion  110  of the inner sheet metal shell  106  at the interface between the inlet  200  and the volute  700 . The tongue member  102  directs exhaust gas received via the inlet  200  defined by the sheet metal structures  104 ,  106  tangentially into the volute  700  at the fluid interface between the inlet  200  and the volute  700 . As described in greater detail below, in embodiments where the tongue member  102  is realized as a cast metal portion of the bearing flange  108 , the cast tongue member  102  achieves better thermomechanical reliability, performance (e.g., tongue shape) and high-cycle fatigue (HCF) behavior (e.g., tongue position) relative to turbine housing designs having additional welding at or near the tongue. 
     Still referring to  FIG. 1 , the divider portion  130  may radially separate the inlet exit end  105  of the inlet sheet metal structure  104  from the volute portion  110  of the inner sheet metal shell  106 . The inner surface of the volute portion  110  of the sheet metal shell  106  is contoured to define the outer contour of the scroll-shaped voided region of the volute passage  700 . The volute passage  700  narrows as gas flows radially starting from the interface with the inlet passage  200  at one end portion  132  of the tongue member  102  until reaching the divider portion  130  at the opposing end of the tongue member  102 , with the divider portion  130  separating the volute  700  from the inlet passage  200 . The volute portion  110  of the inner sheet metal shell  106  includes a voided or cutout region  113  corresponding to the tongue member  102 , with the edges of the cutout region being welded, joined, brazed or otherwise affixed to the radially outer edges of the end portions  130 ,  132  of the tongue member  102  to hermetically seal the volute portion  110  to the tongue member  102 . In this regard, the protruding portions  130 ,  132  of the tongue member  102  are joined to the volute portion  110 . 
     In exemplary embodiments, the bearing flange  108  is realized as a substantially annular unitary cast metal structure having a central opening  109  for receiving or otherwise accommodating a turbine wheel. The bearing flange  108  includes a recessed rim  107  or a similar contoured feature about its peripheral circumference on the surface that faces the sheet metal shell  106  in the axial direction in order to support coupling, joining or otherwise mounting the sheet metal shell  106  to the bearing flange  108 . The recessed mounting feature  107  on the bearing flange  108  may correspond to the outer circumference of the opening of the sheet metal shell  106  facing the bearing flange  108  to mate with the sheet metal shell  106  and establish a welding seam or joint in a radial plane about the interface between the sheet metal shell  106  and the bearing flange  108 . In this regard, the end of the volute portion  110  proximate the bearing flange  108  may include a corresponding rim  111  about the outer circumference of the opening in the inner sheet metal structure  106  that faces the bearing flange  108 , with the rim  111  extending in the axial direction towards the bearing flange  108  to mate with the corresponding recessed feature  107  of the bearing flange  108 . The end of the rim  111  of the sheet metal shell  106  proximate the bearing flange  108  may be joined circumferentially to the corresponding mounting feature  107  of the bearing flange  108  by welding, brazing, etc. to hermetically seal the sheet metal shell  106  to the flange  108  in the axial direction at the interface defined between the corresponding mounting features  107 ,  111 . 
     As described in greater detail below in the context of  FIGS. 7-10 , in some exemplary embodiments, the tongue member  102  is integrated with, integrally formed with, monolithic or one-piece with the bearing flange  108  and realized as a cast feature of the cast bearing flange  108 . That said, in other embodiments, the tongue member  102  may be realized as a separate or discrete sheet metal structure that is welded, brazed, joined or otherwise affixed to the bearing flange  108  to establish a hermetic seal between the sheet metal tongue member  102  and the cast bearing flange  108 , as depicted in  FIG. 1  and described in greater detail below in the context of  FIGS. 11-12 . Referring to  FIG. 3 , independent of whether the tongue member  102  is realized by casting or sheet metal, the tongue member  102  includes a voided or inlet cutout portion  103  that corresponds to or otherwise mates with an end  105  of the inlet sheet metal structure  104  proximate the volute  700  to allow the exit end  105  of the inlet sheet metal structure  104  to be welded, joined or otherwise affixed to the tongue member  102  to hermetically seal the inlet sheet metal structure  104  to the tongue member  102 . In this regard, the shape and dimensions of the inlet cutout portion  103  correspond to the shape and dimensions of the inlet exit end  105  of the inlet sheet metal structure  104  to mate or otherwise fit with the inlet exit end  105  of the inlet sheet metal structure  104 . Adjacent to the inlet cutout portion  103 , the tongue member  102  includes a divider portion  130  that extends in an axial direction to separate or otherwise divide the inlet  200  from the volute  700 . In this regard, the distance or dimension of the extension of the divider portion  130  in the axial direction is greater than the axial dimension of the inlet exit end  105  to physically separate the inlet exit end  105  of the inlet sheet metal structure  104  from the volute portion  110  of the inner sheet metal shell  106 . On the other side of the inlet cutout portion  103 , the tongue member  102  includes an extending portion  132  that extends in an axial direction tangentially to the volute portion  110  at the interface between the inlet sheet metal structure  104  and the volute portion  110 . When the tongue member  102  is realized as a separate sheet metal structure as depicted in  FIGS. 1-3 , the peripheral edge of the base portion of the tongue member  102  includes a rim  121  or similar mounting feature that corresponds to the recessed feature  107  of the bearing flange  108  to mate with the bearing flange  108  similar to the rim  111  of the volute portion  110 . 
     Referring to  FIG. 4 , with continued reference to  FIGS. 1-3 , in exemplary embodiments, the inlet sheet metal structure  104  is contoured or otherwise pressed to provide a substantially U-shaped cross-section that cooperates with the inlet portion  112  of the sheet metal shell  106  to define the contour of the inlet gas passageway. The illustrated inlet sheet metal structure  104  is substantially frustoconical in shape such that the diameter of the exhaust gas passageway for the inlet  200  is tapered and decreases towards the interface with the volute  700  at the tongue member  102  from a larger diameter or opening of the inlet  200  opening  116  at the inlet  200  flange  118  to encourage flow tangential to the volute  700  at the interface with the volute  700 . That said, it should be appreciated the shape and dimensions of the inlet sheet metal structure  104  can vary depending on the needs of a particular embodiment. The opening end of the inlet sheet metal structure  104  opposite the inlet exit end  105  of the inlet sheet metal structure  104  is cooperatively configured to define the opening of the inlet  200  in concert with the corresponding end of the inlet portion  112  of the sheet metal shell  106 . In this regard, the ends of the inlet sheet metal structure  104  and the inlet portion  112  of the sheet metal shell  106  are welded, joined or otherwise affixed to an inlet flange  118  about the circumference of an inlet opening  116  in the flange  118  to hermetically seal the sheet metal structures  104 ,  106  to the inlet flange  118  about the opening  116 . In a similar manner, the edges of the sheet metal structure  104  that face corresponding edges of the inlet portion  112  of the inner sheet metal shell  106  in the axial direction are welded, joined or otherwise affixed to the corresponding edges of the inlet portion  112  to hermetically seal the inlet  200 . 
     Referring to  FIG. 5 , with continued reference to  FIGS. 1-4 , in exemplary embodiments, the length of the extension of the inlet portion  112  from the volute portion  110  corresponds to the length or longitudinal dimension of the inlet sheet metal structure  104 , and the inlet portion  112  is similarly contoured or otherwise pressed to provide a substantially U-shaped cross-section that cooperates with the inlet sheet metal structure  104  to define boundaries of the inlet passage for tangentially directing fluid flow into a volute  700  defined by the volute portion  110 . In this regard, the volute portion  110  is realized as a substantially spiral structure formed into the body of the inner sheet metal shell  106 , for example, by contouring or otherwise pressing the inner sheet metal structure  106  to provide a substantially U-shaped cross-section that defines the volute passage for radially directing a tangential flow received at an interface with the inlet  200  towards a turbine wheel disposed within the volute portion. In this regard, the depth or dimension of the U-shaped cross-section progressively decreases from the interface with the inlet  200  at a first tongue portion  132  towards the opposing end of the tongue portion  130  to decrease the flow area and thereby direct flow received via the inlet  200  towards the turbine wheel, with the volute portion  110  also being configured to provide clearance for the turbine wheel to rotate and extract energy from the exhaust gas fluid flow within the volute passage. The peripheral radial edges of the volute portion  110  include or are realized as a rim, lip, or similar feature  111  that provide a surface for joining the volute portion  110  to a corresponding feature  107  of the bearing flange  108  and provide a substantially circumferential joint aligned in a substantially radial plane, as discussed previously. 
     Referring to  FIG. 6 , with continued reference to  FIGS. 1-5 , an outer containment sheet metal structure  124  (alternatively referred to herein as the outer containment shell) includes a substantially circular opening that is circumferentially joined to the bearing flange  108  to substantially enclose or surround the volute portion  110  of the inner sheet metal shell  106  in the axial direction. In this regard, a diameter of an opening defined through the outer containment shell  124  from the first shell end  125  to the opposite, second shell end varies along the axis of the assembly. In one example, the diameter of the opening at the first shell end  125  of the containment shell  124  proximate the bearing flange  108  is different and greater than the circumference of the volute portion  110  to substantially circumscribe the volute portion  110  of the inner sheet metal shell  106 , and thereby, substantially enclose or surround the volute portion  110  of the inner sheet metal shell  106  in the radial as well as axial direction. In exemplary embodiments, the bearing end  125  of the containment shell  124  extends towards the bearing flange  108  in the axial direction by a greater distance than the rim  111  of the inner sheet metal shell  106  to radially overlap the rim  111  of the inner sheet metal shell  106 . In the illustrated embodiment, the diameter of the opening at the first shell end  125  of the containment shell  124  is different and greater than an outer circumference about the mounting feature  107  to receive at least a portion of the bearing flange  108  within the opening. The first shell end  125  is welded, joined or otherwise affixed to a peripheral surface of the bearing flange  108  to couple the outer containment shell  124  to the bearing flange  108  such that the outer containment shell  124  substantially surrounds the volute portion  110 . In this regard, double welding of the volute portion  110  to the containment shell  124  is avoided by joining the containment shell  124  to the bearing flange  108  via a separate welding procedure. 
     In exemplary embodiments, the outer containment sheet metal shell  124  is realized as a unitary sheet metal structure that is contoured or otherwise pressed to correspond to the volute portion  110  of the inner sheet metal shell  106 . In exemplary embodiments, the inner or interior dimensions of the outer containment shell  124  are greater than the dimensions of the volute portion  110  to provide a space or air gap between the outer containment shell  124  and the inner sheet metal shell  124 , which helps provide physical and thermal isolation between the volute portion  110  and the outer containment shell  124 . The outer containment shell  124  also includes an inlet cutout region  126  that extends in the axial direction from the bearing end  125  by a dimension that is greater than the axial dimension of the inlet portion  112 . IN this regard, the inlet cutout region  126  corresponds to the inlet portion  112  of the inner sheet metal shell  106  and allows the inlet portion  112  to extend from the interface of the volute portion  110  within the interior of the containment shell  124  to beyond the exterior of the containment shell  124  such that the inlet region  112  is not positioned within or is external to the outer containment shell  124 . The containment shell  124  also includes an outlet opening  128  opposite the bearing end  125  to define the axial outlet of the turbine assembly  100 . In exemplary embodiments, the outlet opening  128  in the containment shell  124  is substantially circular and coaxially aligned with the interior opening  504  ( FIG. 5 ) in the inner sheet metal shell  106 . 
     Referring to  FIG. 7 , and with continued reference to  FIGS. 1-6 , a substantially cylindrical outlet pipe  122  is disposed within the outlet opening  128 . The outlet pipe  122  extends in an axial direction from the interior opening  504  in the volute portion  110  of the inner sheet metal shell  106  to an exterior of the turbine assembly  100  for coupling the turbine assembly  100  to a fluid conduit for carrying exhaust gas axially exiting the turbine wheel (e.g., to a downstream emissions device such as a catalytic converter). In exemplary embodiments, the outlet pipe  122  is realized as a unitary sheet metal structure that is inserted into the outlet opening  128  and welded, joined or otherwise affixed about the interior opening  504  in the inner sheet metal shell  106  to hermetically seal the axial outlet pipe  122  to the volute portion  110  such that all gas axially exits the turbine wheel via the outlet pipe  122 . For example, the outer circumference of the end of the outlet pipe  122  proximate to the turbine wheel may be substantially the same diameter as or otherwise correspond to the circumference of the opening  504  to support welding the outlet pipe  122  to the volute portion  110  circumferentially about the opening  504 . In the illustrated embodiments, the outlet pipe  122  is formed to include an intermediary collar portion  129  having a circumference or diameter greater than the circumference in the outlet opening  128  to prevent over- or under-insertion of the outlet pipe  122  into outlet opening  128  and ensure alignment of the bearing end of the outlet pipe  122  with the interior opening  504  in a radial plane. The outlet pipe  122  is also welded, joined or otherwise affixed to the containment shell  124  circumferentially about the outlet opening  128 . The outlet pipe  122  functions to control the exhaust gas flow exiting the turbine assembly  100 , with the collar portion  129  facilitating a V-band clamp or similar connection to ducting or another fluid conduit between the exit end of the outlet pipe  122  and an exhaust system. Welding or joining the outlet pipe  122  about both the interior outlet opening  504  of the volute portion  110  and the corresponding outlet opening  128  of the containment shell  124  supports the mechanical integrity of the turbine assembly  100  and maintains sealing of the volute  700 . 
     Referring to  FIG. 7 , in one or more exemplary embodiments, an insulating material  750  is provided within an air gap  740  defined by the space between the outer containment shell  124  and the inner sheet metal shell  106 . For example, a layer of a thermally-insulating fabric material may be conformably installed on or overlying the volute portion  110  of the inner sheet metal shell  106  from the interface with the bearing flange  108  until reaching the axial outlet opening  504 . In such an embodiment, the thermally-insulating material  750  surrounds or otherwise encompasses the volute portion  110  of the inner sheet metal shell  106  to minimize heat loss from the volute  700  within the air gap  740  between the volute portion  110  and the containment shell  124 , which increases efficiency of the turbine while reducing the temperature of the containment shell  124 . In alternative embodiments, thermally-insulating material may be provided on an interior surface of the containment shell  124 , in lieu of or in addition to providing the thermally-insulating material  750  on the surface of the volute portion  110 . It should be noted that the subject matter described herein is not limited to a thermally-insulating fabric material, and any suitable insulating material or layer or combination thereof may be utilized within the gap between shells  106 ,  124  to achieve improved thermal isolation between the shells  106 ,  124 . 
     Referring again to  FIGS. 1-2 , depending on the particular embodiment, the inlet flange  118  may include bores or other features configured to support mounting or otherwise coupling the inlet flange  118  to the exhaust manifold of an internal combustion engine or other conduit or ducting to receive exhaust gas from the engine. Likewise, depending on the embodiment, the bearing flange  108  may include bores or other features configured to support mounting or otherwise coupling the bearing flange  108  to a rotating assembly that includes a turbine wheel, a rotary shaft, and/or the like. In this regard, when the rotating assembly is mounted to the bearing flange  108 , at least a portion of the blades of the turbine wheel are disposed within the volute  700  defined by the sheet metal shell  106 , with the interior opening  504  in the inner sheet metal shell  106  being substantially circular and coaxially aligned with the rotational axis of the turbine wheel to receive or otherwise accommodate a nose of the turbine wheel and define the axial outlet  120  for the turbine. 
     Referring now to  FIGS. 8-11 , fabrication of the turbine assembly  100  will now be described in the context of embodiments where the bearing flange  108  and the tongue member  102  are integral and realized as a unitary cast metal structure  800 . In this regard, the cast metal structure  800  includes a cast tongue portion  802  corresponding to the tongue member  102  that is integral with an annular body portion  804  corresponding to the bearing flange  108 . In a similar manner as described above, the cast tongue member  802  protrudes from the bearing flange body portion  804  in an axial direction and includes a raised divider portion  830  (e.g., divider portion  130 ) that extends axially from the base of the tongue member  802  to separate or otherwise divide the inlet passage from the volute. The opposing end of the cast tongue member  802  also includes a raised portion  832  (e.g., portion  132 ) that is oriented tangential to the volute. The cutout portion  803  of the tongue member  802  extends from the bearing flange body portion  804  between the raised portions  830 ,  832  is configured to receive and support the inlet exit end  105  of the inlet sheet metal structure  104 , as depicted in  FIG. 9 . In this regard, the cutout portion  803  elevates the inlet exit end  105  of the inlet sheet metal structure  104  such that the inlet sheet metal structure  104  is spaced apart from and does not contact the bearing flange body portion  804 . 
     Referring to  FIG. 9 , the inlet exit end  105  of the inlet sheet metal structure  104  is initially welded, joined or otherwise affixed to the tongue portion  802  of the cast metal structure  800  about the interface to the volute defined by the edges of the cutout portion  803  that mate with or are otherwise configured to receive the inlet exit end  105 . Stated another way, the inlet exit end  105  of the inlet sheet metal structure  104  is coupled to or received within the cut-out portion of the tongue portion  802 , and the sides of the end  105  are coupled, joined or fixed to the sides of the recess. Referring to  FIG. 10 , after welding the inlet exit end  105  of the inlet sheet metal structure  104  to the cutout portion  803  of the cast tongue member  802 , the inner sheet metal shell  106  is positioned over the assembled structures  104 ,  800  and then welded, joined or otherwise affixed to the cast bearing flange portion  804  about the periphery of the bearing flange portion  804  (e.g., by welding the rim  111  of the volute portion  110  of the inner sheet metal shell  106  to a corresponding feature  107  of the bearing flange  804 ), with the edges of the cutout region  113  of the volute portion  110  being concurrently welded or joined to the raised tongue portions  830 ,  832  to hermetically seal the volute between the inner sheet metal shell  106  and the bearing flange  800 . In this regard, the tongue member  802  is disposed within the cutout region  113  of the volute portion  110 , with the raised portions  830 ,  832  of the tongue member  802  radially separating the volute portion  110  from contacting the inlet exit end  105  of the inlet sheet metal structure  104 . The axially outward facing edges of the inlet sheet metal structure  104  and the inner facing edges of the inlet portion  112  of the inner sheet metal shell  106  are also welded, joined or otherwise affixed together to hermetically seal the inlet  200 . After assembling the sheet metal structures  104 ,  106  with the cast metal structure  800 , a thermally-insulating material may be provided on the outer surface of the volute portion  110  or the inner surface of the containment shell  124  before positioning the containment shell  124  over the volute portion  110  and inserting the outlet pipe  122  within the axial outlet openings  128 ,  304 . 
     After assembling the inner sheet metal shell  106  within the containment shell  124  such that the gap is defined between sheet metal shells  106 ,  124 , and the outer containment shell  124  is welded, joined or otherwise affixed to the bearing flange portion  804 , resulting in the turbine housing assembly depicted in  FIG. 11 . Thereafter, the outlet pipe  122  is disposed within the axial outlet openings  128 ,  504  of the sheet metal shells  106 ,  124  and welded, joined or otherwise affixed about the respective axial outlet openings  128 ,  304  of the sheet metal shells  106 ,  124 . Thereafter, the inlet flange  118  is welded, joined or otherwise affixed to the inlet sheet metal structure  104  and the inlet portion  112  of the inner sheet metal shell  106  about the inlet opening  116  to complete fabrication of the turbine housing assembly  100 . The turbine housing assembly  100  may then be installed or otherwise mounted to a rotating assembly and the appropriate ducting or conduits for fluid flow to/from the turbine housing assembly  100 , the details or which are not germane to disclosure. 
     Referring now to  FIGS. 12-13 , fabrication of the turbine housing assembly  100  will now be described in the context of embodiments where the tongue member  102  is realized as a separate sheet metal structure as depicted in  FIG. 1 . In a similar manner as described above, the inlet exit end  105  of the inlet sheet metal structure  104  is initially welded, joined or otherwise affixed to the tongue member  102  about the interface to the volute defined by the edge of the cutout portion  103 , as shown in  FIG. 12 . Thereafter, the inner sheet metal shell  106  is positioned over the assembled structures  102 ,  104  and then welded, joined or otherwise affixed to the raised tongue portions  130 ,  132  and the facing edges of the inlet sheet metal structure  104  as shown in  FIG. 13 , in a similar manner as described above. After assembling the sheet metal structures  102 ,  104 ,  106  together, the periphery of the volute portion  110  of the inner sheet metal shell  106  and the tongue member  102  are welded, joined or otherwise affixed to the bearing flange  108 , for example, by welding the rim  111  of the volute portion  110  of the inner sheet metal shell  106  and the rim  121  of the tongue member  102  to the corresponding mounting feature  107  of the bearing flange  108 . After joining the tongue member  102  and the volute portion  110  to the bearing flange  108 , fabrication of the turbine housing assembly  100  may be completed in a similar manner as described above (e.g., applying a thermal insulation layer to the volute portion  110  or the containment shell  124 , positioning the containment shell  124  over the volute portion  110  to define the gap and welding the containment shell  124  to the bearing flange  108 , assembling the outlet pipe  122  within the sheet metal shells  106 ,  124 , and welding the outlet pipe  122  about the corresponding openings  128 ,  304  in the sheet metal shells  106 ,  124 , etc.). 
     To briefly summarize, the subject matter described herein provides a sheet metal turbine housing assembly capable of being manufactured using standardized turbine housing subcomponents to provide improved flexibility while also reducing costs compared to cast turbine housings, which are often the most expensive component of a turbocharger due to their size, complexity and material requirements. Cast turbine housings may also require specialized casting hardware for variations in the size, shape, and/or packaging constraints for the turbine housing to accommodate different applications or installations, while also requiring greater minimum wall thicknesses that increase costs while also increasing the mass and thermal inertia of the turbine housing. In contrast, the sheet metal structures described herein may be designed or otherwise configured to support multiple different configurations or applications. 
     For example, referring to  FIGS. 1-2 and 6 , the inlet cutout opening  126  in the outer containment shell  124  may be configured to provide clearance with respect to the inlet  200  that allows the orientation of the outer containment shell  124  to be rotatably adjusted with respect to the bearing flange  108  and the volute portion  110  according to final assembly requirements for installing the turbine housing assembly  100  in a vehicle to provide flexibility across different applications or installations. Additionally, the thickness of the outer containment shell  124  may be minimized by the sheet metal forming process to reduce weight and material costs and lower thermal inertia while maintaining containment capability. In some embodiments, the thermal insulation layer  750  is provided on the inner surface of the containment shell  124  (e.g., from the bottom inner edge to the upper inner edge to cover the entire interior surface) to minimize heat loss and reduce the temperature of the outer surface of the containment shell  124  to increase efficiency by reducing thermal losses (and improving the efficiency of a downstream catalytic converter or other emission controls by maintaining available energy and higher temperature for the exhaust gas flow). The design of the containment shell  124  can be standardized for compatibility with standardized designs of the other sheet metal structures  104 ,  106  via a standardized connection component (e.g., outlet pipe  122 ), which allows the containment shell  124  to be utilized across a wide range of turbocharger applications that share a common or standardized volute design. 
     Referring to  FIGS. 1-2 and 5 , the volute portion  110  of the inner sheet metal shell  106  may be designed and manufactured as a standardized component capable of use across a range of turbocharger applications sharing the same aerodynamic volute definition (with a corresponding cost reduction attendant to component standardization). The inlet portion  112  of the inner sheet metal shell  106  and the inlet sheet metal structure  104  may be designed and manufactured to accommodate different application-specific packaging requirements and varied across different instances of the volute portion  110 . In this regard, the shape, size, and other physical characteristics of the volute portion  110  and the tongue member  102  may be standardized and maintained substantially constant across different applications, while the dimensions of the inlet sheet metal structure  104  and the inlet portion  112  vary to suit the needs of a particular application or installation. For example, the tongue member  102 , the volute portion  110 , the outer containment shell  124  and/or the outlet pipe  122  may be designed for universal use, while the shape and/or dimensions of the inlet sheet metal structure  104  and the inlet portion  112  may be varied depending on the application. In this manner, the sheet metal turbine housing assembly provides a flexible entrance adjustment capable of accommodating different installations. The thicknesses of the inner sheet metal shell  106  and the inlet sheet metal structure  104  may similarly be minimized by the sheet metal forming process to achieve low thermal inertia, with the thermal insulation layer  750  within the gap between the volute portion  110  and the outer containment shell  124  minimizing thermal losses. 
     For the sake of brevity, conventional techniques related to turbines, compressors, turbochargers, wastegates, bypass valves, ducting, catalytic converters, emissions controls, and other functional aspects of the systems (and the individual operating components of the systems) may not be described in detail herein. Furthermore, the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in an embodiment of the subject matter. 
     The foregoing description may refer to elements or components or features being “coupled” together. As used herein, unless expressly stated otherwise, “coupled” means that one element/node/feature is directly or indirectly joined to (or directly or indirectly communicates with) another element/node/feature, and not necessarily mechanically. Thus, although the drawings may depict one exemplary arrangement of elements, additional intervening elements, devices, features, or components may be present in an embodiment of the depicted subject matter. In addition, certain terminology may also be used in the following description for the purpose of reference only, and thus are not intended to be limiting. For example, the terms “first,” “second,” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. Similarly, terms such as “upper”, “lower”, “top”, and “bottom” refer to directions in the drawings to which reference is made. 
     It should be noted that many alternative or additional functional relationships or physical connections may be present in an embodiment of the present disclosure. In addition, while the figures shown herein depict an example with certain arrangements of elements, additional intervening elements, devices, features, or components may be present in an actual embodiment. It should also be understood that the drawings are merely illustrative and may not be drawn to scale. 
     The foregoing detailed description is merely illustrative in nature and is not intended to limit the embodiments of the subject matter or the application and uses of such embodiments. As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Any implementation described herein as exemplary is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, there is no intention to be bound by any theory presented in the preceding background, brief summary, or the detailed description. 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the subject matter in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the subject matter. It should be understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the subject matter as set forth in the appended claims. Accordingly, details of the exemplary embodiments or other limitations described above should not be read into the claims absent a clear intention to the contrary.