exhaust turbine and turbocharger

Abstract

An aspect of an exhaust turbine according to the present disclosure is provided with: a rotating shaft; a turbine wheel attached to one end side of the rotating shaft; a turbine housing having a scroll portion formed on an outer peripheral side of the turbine wheel; a bearing housing that accommodates a bearing for supporting the rotating shaft; a fastening member that fastens a first flange portion of the turbine housing and a second flange portion of the bearing housing together; and a heat-shielding plate having an outer peripheral edge portion held between the first flange portion and the second flange portion. In a first cross section that passes through the center of the rotating shaft and a tongue portion of the turbine housing along an axial direction of the rotating shaft, when the innermost position, in a radial direction of the rotating shaft, of a contact surface between the first flange portion and the outer peripheral edge portion of the heat-shielding plate is defined as a first seal inner end, the innermost position, in the radial direction, of a contact surface between the second flange portion and the outer peripheral edge portion of the heat-shielding plate is defined as a second seal inner end, and one of the first seal inner end and the second seal inner end that is positioned outside in the radial direction is defined as a seal inner end, the seal inner end is disposed outside the tongue portion in the radial direction.

Description

[Technical Field]

[0001] The present disclosure relates to an exhaust turbine and a turbocharger including the exhaust turbine. [Background technology]

[0002] The turbine housing of an exhaust turbocharger has a heat shield sandwiched between it and the bearing housing to prevent exhaust gases flowing inside the turbine housing from leaking into the bearing housing and to prevent the heat contained in the exhaust gases from being transmitted to the bearing housing. Patent documents 1 and 2 disclose a fastening method for fastening flange portions formed on a turbine housing and a bearing housing using a ring-shaped coupling member with a truncated V-shaped cross section, with a heat shield sandwiched between the flange portions formed on the abutment portion of the turbine housing and the bearing housing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-167971 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-117483 Summary of the Invention [Problem to be solved by the invention]

[0004] The turbine housing has a tongue at the boundary where exhaust gas flows from the scroll passage to the exhaust gas inlet passage housing the turbine wheel. The heat of the exhaust gas causes uneven thermal deformation near the tongue. This can cause uneven deformation of the flange and coupling member formed at the contact point between the turbine housing and the bearing housing, resulting in a problem of insufficient sealing between the flange and the heat shield. Another problem is that the fastening force of the coupling member becomes uneven around the rotating shaft or is insufficient, making it impossible to ensure sealing performance.

[0005] SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to solve the above problems and to ensure sealing performance between a turbine housing and a bearing housing against thermal deformation near the tongue portion due to the heat of exhaust gas. [Means for solving the problem]

[0006] In order to achieve the above object, one aspect of an exhaust turbine according to the present disclosure includes a rotating shaft, a turbine wheel attached to one end of the rotating shaft, a turbine housing that accommodates the turbine wheel, wherein a scroll portion that introduces exhaust gas into the turbine wheel is formed on the outer periphery of the turbine wheel, a bearing housing that accommodates a bearing that supports the rotating shaft, wherein the bearing housing is provided adjacent to the turbine housing, fastening members for fastening a first flange portion of the turbine housing to a second flange portion of the bearing housing, and a heat shield plate that is arranged between the turbine housing and the bearing housing, wherein an outer periphery of the heat shield plate is formed on the outer periphery of the first flange. and a heat shield plate sandwiched between the flange portion and the second flange portion, and in a first cross section along the axial direction of the rotating shaft that passes through the center of the rotating shaft and the tongue portion of the turbine housing, if the innermost position in the radial direction (hereinafter also simply referred to as the "radial direction") of the rotating shaft on the abutment surface between the first flange portion and the outer peripheral edge portion of the heat shield plate is defined as a first seal inner end, the innermost position in the radial direction on the abutment surface between the second flange portion and the outer peripheral edge portion of the heat shield plate is defined as a second seal inner end, and the one of the first seal inner end and the second seal inner end that is located outward in the radial direction is defined as a seal inner end, the seal inner end is positioned radially outward from the tongue portion. [Effects of the Invention]

[0007] According to one aspect of the exhaust turbine and turbocharger disclosed herein, even if uneven thermal deformation occurs near the tongue portion formed in the turbine housing through which exhaust gas flows, the sealing performance of the sealing surface formed at the abutment portion between the turbine housing and the bearing housing and between the flange portion and the heat shield plate can be maintained at a high level. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of an engine equipped with a supercharger according to one embodiment; [Figure 2] FIG. 1 is a vertical cross-sectional view showing a portion of a turbocharger according to an embodiment. [Figure 3] FIG. 2 is an enlarged longitudinal cross-sectional view of a portion of an exhaust turbine unit according to an embodiment of the present invention. [Figure 4] FIG. 4 is a plan view showing an example of a configuration of a tongue portion formed on a turbine housing as viewed from above. [Figure 5A] FIG. 10 is a plan view of another example of the configuration of the tongue portion as viewed from above. [Figure 5B] FIG. 10 is a plan view of yet another example of the configuration of the tongue portion as viewed from above. [Figure 6] FIG. 2 is an enlarged longitudinal cross-sectional view of a portion of an exhaust turbine unit according to an embodiment of the present invention. [Figure 7] FIG. 2 is a front view of a fastening member according to an embodiment. [Figure 8] FIG. 2 is an enlarged longitudinal cross-sectional view of a portion of an exhaust turbine unit according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in these embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprises," "includes," "has," "includes," or "has" one element are not exclusive expressions that exclude the presence of other elements.

[0010] FIG. 1 is a schematic configuration diagram of an engine equipped with a supercharger according to one embodiment, and FIG. 2 is a vertical cross-sectional view showing a part of the supercharger. 1, an engine 10 equipped with a turbocharger 30 has, for example, four cylinders 12a, 12b, 12c, and 12d inside an engine body 14, and compressed air is supplied to these four cylinders via an intake manifold 18. This compressed air is supplied from a compressor section 32 that constitutes a part of the turbocharger 30. Fuel air a is supplied to the compressor section 32, and the fuel air a is compressed by the compressor section 32. The compressed air is supplied to each of the cylinders 12a to 12d via the intake pipe 16 and the intake manifold 18. Exhaust gas e discharged from each of the cylinders 12a to 12d is sent to an exhaust turbine section 34 that constitutes a part of the turbocharger 30 via an exhaust manifold 20 and an exhaust pipe 22, and rotates a turbine wheel 40 housed inside a turbine housing 42.

[0011] As shown in FIG. 2, the turbocharger 30 includes an exhaust turbine unit 34 provided on one end side of a rotary shaft 36 (the end side in the direction indicated by arrow b in FIG. 2). The exhaust turbine unit 34 includes a turbine wheel 40 attached to one end side of the rotary shaft 36 and a turbine housing 42 that houses the turbine wheel 40. The compressor unit 32 is provided on the other end side of the rotary shaft 36 (the end side in the direction indicated by arrow c in FIG. 2), and the turbine wheel 40 is connected via the rotary shaft 36 to a compressor wheel 32b housed inside a compressor housing 32a. The rotation of the turbine wheel 40 rotates the compressor wheel 32b, and the rotation of the compressor wheel 32b causes fuel air a to be drawn into the compressor housing 32a, where it is compressed by the compressor wheel 32b, and the compressed air is supplied to each of the cylinders 12a to 12d.

[0012] As shown in FIG. 2 , the turbine housing 42 has a scroll portion 44 formed on the outer periphery of the turbine wheel 40. The turbine housing 42 has an exhaust gas introduction portion 46 inside the scroll portion 44. Inside the exhaust gas introduction portion 46, a plurality of blades 48 are radially provided on the outer periphery of the turbine wheel 40 along the circumferential direction of the rotating shaft 36 (hereinafter simply referred to as the "circumferential direction"), and an exhaust gas introduction passage 50 is formed between each blade 48. Exhaust gas e flows into the exhaust gas introduction passage 50 from a flow path formed in the scroll portion 44, rotates the turbine wheel 40, and then flows out of the exhaust gas introduction passage 50.

[0013] A bearing housing 38 is provided adjacent to the turbine housing 42 on the other side of the turbine housing 42 (the side in the direction indicated by arrow c in FIG. 2). A bearing 52 that rotatably supports the rotating shaft 36 is accommodated in the bearing housing 38. The compressor unit 32 is provided on the further other side of the bearing housing 38. In FIG. 2, the symbol O indicates the central axis that is the center of rotation of the rotating shaft 36.

[0014] The turbocharger 30 according to the embodiment shown in Fig. 2 is a twin-scroll turbocharger, and two rear-side exhaust gas passages 54 and a front-side exhaust gas passage 56 are formed in the scroll section 44. In this case, the exhaust manifold 20 and the exhaust pipe 22 are divided into two systems, and the exhaust gas passage formed by the exhaust manifold and exhaust pipe of one system communicates with the rear-side exhaust gas passage 54, and the exhaust gas passage formed by the exhaust manifold and exhaust pipe of the other system communicates with the front-side exhaust gas passage 56. The twin-scroll type is designed so that the flow capacities of the exhaust gas flowing through these exhaust gas passages are equal, so that no pressure difference occurs between the pressure of the exhaust gas flowing through the rear-side exhaust gas passage 54 and the pressure of the exhaust gas flowing through the front-side exhaust gas passage 56.

[0015] In the scroll section 44, the spirally formed exhaust gas flow path gradually narrows downstream, causing the exhaust gas to flow at an accelerated rate into the exhaust gas introduction passage 50. A rear-side tongue portion 58 and a front-side tongue portion 60 are formed at the terminal ends (ends of the spiral) of the rear-side exhaust gas flow path 54 and the front-side exhaust gas flow path 56, which also serve as the inlets of the exhaust gas introduction passage 50.

[0016] Although the embodiment shown in FIG. 2 is an embodiment applied to a twin-scroll type turbocharger, the exhaust turbine according to the present disclosure can also be applied to a single-scroll type turbocharger.

[0017] In Figure 2, a first flange portion 62 is formed at the other end of the turbine housing 42 (the end in the direction indicated by arrow c in Figure 2), and a second flange portion 64 is formed at one end of the bearing housing 38 (the end in the direction indicated by arrow b in Figure 2). The flange portions 62 and 64 are fastened together with fastening members 66, thereby connecting the turbine housing 42 and the bearing housing 38 to each other. A heat shield plate 68 is disposed between the first flange portion 62 and the second flange portion 64, which are fastened together with the fastening members 66. In other words, an outer peripheral edge portion 68a of the heat shield plate 68 is sandwiched between the flange portions 62 and 64.

[0018] Fig. 3 corresponds to a vertical cross-sectional view further enlarging the vicinity of part A in Fig. 2, and shows an exhaust turbine section 34a according to one embodiment. That is, Fig. 3 is a cross-section along the axial direction of the rotating shaft 36 (a direction along the central axis O; hereinafter, also simply referred to as the "axial direction"), and shows a cross-section (first cross-section) passing through the center (central axis O) of the rotating shaft 36 and the rear-side tongue portion 58. Furthermore, Fig. 3 omits the rotating shaft 36 and the turbine wheel 40, and the symbol O indicates the position of the central axis O of the rotating shaft 36 when the rotating shaft 36 is arranged.

[0019] As shown in Fig. 3, the first flange portion 62 and the outer peripheral edge portion 68a of the heat shield plate 68 abut against each other over a portion of their radial area, forming a first seal surface S1. The second flange portion 64 and the outer peripheral edge portion 68a of the heat shield plate 68 abut against each other over a portion of their radial area on the opposite side of the outer peripheral edge portion 68a from the first seal surface S1, forming a second seal surface S2. In Fig. 3, point Si1 indicates the radially innermost position (first seal inner end) of the abutment surface (first seal surface S1) between the first flange portion 62 and the outer peripheral edge portion 68a of the heat shield plate 68. Point Si2 indicates the radially innermost position (second seal inner end) of the abutment surface (second seal surface S2) between the second flange portion 64 and the outer peripheral edge portion 68a of the heat shield plate 68. Of the first seal inner end Si1 and the second seal inner end Si2, the seal inner end Si0 (which corresponds to the first seal inner end Si1 in this embodiment) located radially outward is positioned radially outward from the rear side tongue portion 58.

[0020] The inner seal end Si0 is the radially inner end of the region where the seal surfaces S1 and S2 formed on both sides of the outer peripheral edge 68a of the heat shield 68 overlap in the radial direction, i.e., the region where the seal pressure of the seal surfaces S1 and S2 is the highest (hereinafter also referred to as the "high seal pressure region"). In Figure 3, the high seal pressure region is indicated by the symbol Rhs. In this embodiment, the radial outer end of the first seal surface S1 (the first seal outer end So1 described later) and the radial outer end of the second seal surface S2 (the second seal outer end So2 described later) are located at approximately the same radial position, so the area between the first seal inner end Si1 and the first seal outer end So1 becomes the high seal pressure area Rhs.

[0021] According to this embodiment, the seal inner end Si0 (first seal inner end Si1) is located radially outward of the rear-side tongue portion 58, and therefore the high sealing pressure region Rhs is located radially outward away from the portion of the rear-side tongue portion 58 that is affected by non-uniform thermal deformation. This makes it possible to prevent the seal surfaces S1 and S2 formed on both side surfaces of the outer peripheral edge portion 68a of the heat shield 68 from being affected by non-uniform thermal deformation of the rear-side tongue portion 58. This makes it possible to maintain the sealing performance of the seal surfaces S1 and S2.

[0022] In this embodiment, the front-side exhaust gas passage 56 is located behind the rear-side exhaust gas passage 54 with respect to the heat shield 68, and is located axially away from the first flange portion 62 via the rear-side exhaust gas passage 54. Therefore, thermal deformation near the front-side tongue portion 60 has almost no effect on the first flange portion 62. Therefore, in this embodiment, thermal deformation of the turbine housing 42 that occurs near the front-side tongue portion 60 is not taken into consideration.

[0023] In the embodiment shown in FIG. 3, the rear side tongue portion 58 is located on the bearing housing 38 side, and the lower portion D near the partition wall surface (partition wall surface 54a described later) of the scroll portion 44 is used as a comparison reference, and the inner end Si0 is located radially outward of the lower portion D.

[0024] The heat shield plate 68 has an annular shape and is arranged over the entire circumferential area of ​​the turbine wheel 40 so as to surround the turbine wheel 40 . The configuration according to this embodiment is applied only to the region near the first cross section where the rear-side tongue portion 58 is formed at the very least, and does not necessarily have to be applied to the entire circumferential area.

[0025] 4, 5A, and 5B are plan views of examples of the shape of the rear-side tongue portion 58, viewed from the upstream side in the flow direction of exhaust gas. In these figures, reference numeral 54a denotes a partition wall surface located on the other side (the side in the direction of arrow c) of the partition wall surfaces of the scroll section 44 that form the rear-side exhaust gas passage 54, and reference numeral 45a denotes a partition wall surface facing the rear-side exhaust gas passage 54 of the partition wall 45 that separates the rear-side exhaust gas passage 54 from the front-side exhaust gas passage 56. Reference numeral 59 denotes a downstream end in the flow direction of the exhaust gas e, and reference numeral Tn denotes a reference line that serves as a reference for determining the radial position of the rear-side tongue portion 58. The position of the reference line Tn is determined from the perspective of a location where heat flux is greatest when the heat retained in the exhaust gas e is transferred to the turbine housing 42 via the rear-side tongue portion 58. In this embodiment, it can be said that the radial position of the rear-side tongue portion 58 is based on the position of the reference line Tn.

[0026] In the rear-side tongue portion 58a shown in Figure 4, the downstream end 59 is located at the most downstream side of both partition walls 45a and 54a in the flow direction of the exhaust gas e, and has an arc-shaped shape located at the most upstream side at the midpoint M (center of the flow) between both partition walls 45a and 54a, and the reference line Tn is determined to pass through the midpoint M. 5A, the downstream end 59 of the rear-side tongue portion 58b is located at the same position across the entire width of the rear-side exhaust gas flow path 54 relative to the flow direction of the exhaust gas e, and the reference line Tn is set to pass through the downstream end 59. In other words, the downstream end 59 coincides with the reference line Tn. 5B, the downstream end 59 has a parabolic shape that is located at points X and Y on both partition walls 45a and 54a on the most upstream side in the flow direction of the exhaust gas e and at a midpoint M on the most downstream side in the flow direction of the exhaust gas e, and a reference line Tn is defined to pass through the most upstream positions (points X and Y) of the rear tongue 58c. That is, the reference line Tn is in a direction perpendicular to the flow direction of the exhaust gas e (the width direction of the rear exhaust gas flow path 54) and is a line that passes through the most upstream position of the downstream end 59 in the flow direction of the exhaust gas e.

[0027] Fig. 6 is an enlarged longitudinal cross-sectional view (first cross-section) of a portion of an exhaust turbine section 34b according to another embodiment. In Fig. 6, a fastening member 66a according to one embodiment includes a base portion 70 disposed on the outer circumferential sides of the first flange portion 62 and the second flange portion 64, a first fastening portion 72 extending radially inward from the base portion 70 along the back surface 62a of the first flange portion 62, and a second fastening portion 74 extending radially inward from the base portion 70 along the back surface 64a of the second flange portion 64.

[0028] 6 (first cross section), point So1 indicates the radially outermost position (first seal outer end) of the contact surface (first seal surface S1) between the first flange portion 62 and the outer peripheral edge portion 68a of the heat shield plate 68. Also in the same figure, point So2 indicates the radially outermost position (second seal outer end) of the contact surface (second seal surface S2) between the second flange portion 64 and the outer peripheral edge portion 68a of the heat shield plate 68. The one of the first seal outer end So1 and the second seal outer end So2 that is located radially inward is referred to as the seal outer end So0. In this embodiment, the first seal outer end So1 and the second seal outer end So2 are located at approximately the same position in the radial direction, so either the first seal outer end So1 or the second seal outer end So2 corresponds to the seal outer end So0.

[0029] 6, the symbol Ti1 indicates the radially innermost position (first fastening inner end) of the contact surface (first pressure surface Ps1) between the first fastening portion 72 and the back surface 62a of the first flange portion 62. The symbol Ti2 indicates the radially innermost position (second fastening inner end) of the contact surface (second pressure surface Ps2) between the second fastening portion 74 and the back surface 64a of the second flange portion 64. If the radially outer one of the first fastening inner end Ti1 and the second fastening inner end Ti2 is defined as the fastening inner end Ti0, the seal outer end So0 is positioned radially inward of the fastening inner end Ti0.

[0030] The inner fastening end Ti0 is the inner end of a radial region (hereinafter also referred to as a "high fastening pressure region") in which fastening forces are applied to the first flange portion 62 and the second flange portion 64 from both the first fastening portion 72 and the second fastening portion 74. In Figure 6, the high fastening pressure region is indicated by the symbol Rht. 6, the first fastening inner end Ti1 and the second fastening inner end Ti2 are at approximately the same position in the radial direction, so the first fastening inner end Ti1 or the second fastening inner end Ti2 becomes the fastening inner end Ti0. Here, "the same position in the radial direction" means that the distances from the central axis O of the rotation shaft 36 on a line perpendicular to the central axis O are equal. In addition, the radially outer end of the first pressure surface Ps1 (a first fastening outer end To1 described later) is located radially inward of the radially outer end of the second pressure surface Ps2 (a second fastening outer end To2 described later), so the first pressure surface Ps1 forms the high fastening pressure region Rht.

[0031] According to this embodiment, the seal outer end So0 (the first seal outer end So1 or the second seal outer end So2; the radially outer end of the high sealing pressure region Rhs) is located radially inward of the fastening inner end Ti0 (the inner end of the high fastening pressure region Rht). Therefore, the high sealing pressure region Rhs is located radially inward and away from the high fastening pressure region Rht, where the flange portions 62 and 64 receive the greatest fastening force from the fastening members 66a. As a result, even if the fastening force of the fastening members 66b is unevenly distributed around the flange portions 62 and 64, the unevenness in the circumferential direction of the fastening force applied to the seal surfaces S1 and S2 is alleviated, thereby ensuring the sealing performance of these seal surfaces.

[0032] In one embodiment, the base portion 70 is provided over almost the entire circumferential area so as to surround the first flange portion 62 and the second flange portion 64 from the outer periphery side. In one embodiment, the base portion 70 has a gap (opening) formed in a portion of its circumference, and flange portions (not shown) are provided at both circumferential ends of the base portion 70 on either side of the gap. These flange portions protrude radially outward and are arranged to face each other. Then, by bringing these flange portions close to each other with a fastener such as a bolt, the fastening member 66 fastens the first flange portion 62 and the second flange portion 64 together.

[0033] In one embodiment, the first fastening portion 72 and the second fastening portion 74 of the fastening member 66 do not necessarily have to be provided over the entire circumferential direction, but only need to be provided near the first cross section where the rear side tongue portion 58 is present.

[0034] 6, the base 70a of the fastening member 66a has an extending portion that extends linearly along the axial direction. The back surface 62a of the first flange portion 62 and the back surface 64a of the second flange portion 64 are inclined surfaces that slope radially inward and away from each other. The first fastening portion 72 extends radially inward along the back surface 62a of the first flange portion 62, and the second fastening portion 74 extends radially inward along the back surface 64a of the second flange portion 64.

[0035] According to this embodiment, a fastening tool such as a bolt is used to narrow a gap (opening) formed in a portion of the circumference of the base 70, and as the diameter of the base 70 shrinks, the first fastening portion 72 slides radially inward along the back surface 62a of the first flange portion 62, and the second fastening portion 74 slides radially inward along the back surface 64a of the second flange portion 64. This allows efficient application of fastening force to the first flange portion 62 and the second flange portion 64, and prevents the fastening force of the fastening member 66 from becoming uneven in the circumference.

[0036] 7, a fastening member 66b is used depending on the shape of the tip end of the first flange portion 62 and the second flange portion 64. The fastening member 66b has a base portion 70b that does not extend along the axial direction, and the fastening member 66b has an overall V-shape. In another embodiment (not shown), the fastening member has a base extending along the axial direction and first and second fastening portions extending radially inward from both ends of the base in a direction perpendicular to the axial direction. According to this embodiment, the first and second fastening portions are not shaped to fit the back surfaces 62a and 64a of the flanges 62 and 64, so there is no need to process the first and second fastening portions relative to the base so that their angles match the back surfaces 62a and 64a of the flanges. This simplifies processing.

[0037] In one embodiment, as shown in Figure 6, one of the first flange portion 62 and the second flange portion 64 has at least one inner convex portion 80 formed radially outward from the outer peripheral edge portion 68a of the heat shield plate 68, which protrudes toward the other of the two flange portions 62 and 64, and the other flange portion has at least one outer convex portion 82 formed radially outward from the inner convex portion 80, whose outer peripheral surface abuts the inner peripheral surface of the inner convex portion 80.

[0038] According to this embodiment, the heat shield 68 is provided with an inner convex portion 80 and an outer convex portion 82 on the radially outer side of the outer peripheral edge portion 68a, and the outer peripheral surface 80a of the inner convex portion 80 and the inner peripheral surface 82a of the outer convex portion 82 have abutting surfaces where they abut against each other, and these abutting surfaces form a sealing surface, thereby further improving sealing performance. In addition, the presence of the inner convex portion 80 and the outer convex portion 82 makes it possible to prevent axial misalignment between the turbine housing 42 and the bearing housing 38.

[0039] In the embodiment illustrated in FIG. 6, the inner ridge 80 projects from the second flange portion 64 toward the first flange portion 62, and the outer ridge 82 projects from the first flange portion 62 toward the second flange portion 64. In another embodiment, the inner ridge 80 may be formed to protrude from the first flange portion 62 toward the second flange portion 64, and the outer ridge 82 may be formed to protrude from the second flange portion 64 toward the first flange portion 62.

[0040] 6, the inner protrusion 80 and the outer protrusion 82 have a rectangular cross section in the first cross section. The protrusion amount of the inner protrusion 80 is approximately the same as the plate thickness of the outer peripheral edge 68a of the heat shield plate 68. On the other hand, the inner protrusion 80 and the outer protrusion 82 may have a cross section other than a rectangular cross section in the first cross section.

[0041] 6 , the outer protrusion 82 is formed on the first flange portion 62. According to this embodiment, the outer protrusion 82 is formed on the first flange portion 62, and the outer peripheral surface of the outer protrusion 82 is an open surface. Therefore, thermal deformation of the outer protrusion 82 caused by heat transferred from the rear-side exhaust gas flow path 54 and the front-side exhaust gas flow path 56 to the first flange portion 62 is not transferred significantly to the second flange portion 64. Therefore, it is possible to prevent a deterioration in the sealing performance of the second sealing surface S2 on the second flange portion 64 side due to thermal deformation of the first flange portion 62.

[0042] In the embodiment shown in Fig. 6, a protrusion 65 is formed so as to protrude radially outward from the outer circumferential side of the second flange portion 64. The protrusion 65 has an end face 65b that faces the end face 82b of the outer protrusion 82. By forming the protrusion 65, the second pressure surface Ps2 can be widened radially outward. This increases the fastening force of the second fastening portion 74.

[0043] In one embodiment, in the cross section (first cross section) shown in FIG. 6, the radial length of the region (first seal surface S1) between the first seal outer end So1 and the first seal inner end Si1 is smaller than the radial length of the region (second seal surface S2) between the second seal outer end So2 and the second seal inner end Si2 (S1 <S2)。

[0044] According to this embodiment, since the radial length of the first sealing surface S1 is smaller than the radial length of the second sealing surface S2, the amount of heat transmitted from the first flange portion 62 to the bearing housing 38 via the outer peripheral edge portion 68a of the heat shield 68 can be suppressed. As a result, the temperature rise of the bearing housing 38 is suppressed, and the thermal deformation of the bearing housing 38 is suppressed, so that the deterioration of the sealing performance of the second sealing surface S2 can be suppressed. Also, since the thermal stress generated in the bearing housing 38 due to the temperature rise can be suppressed, the fatigue life of the bearing housing 38 is also improved. Furthermore, since the area of the first sealing surface S1 becomes smaller, the contact surface pressure applied per unit area of the first sealing surface S1 becomes higher, so that the sealing performance of the first sealing surface S1 can be improved.

[0045] FIG. 8 is a longitudinal sectional view (first section) showing an exhaust turbine section 34c according to another embodiment. In FIG. 8, point To1 indicates the outermost position (first fastening outer end) in the radial direction within the contact surface (first pressing surface Ps1) between the first fastening portion 72 and the back surface 62a of the first flange portion 62. Point To2 indicates the outermost position (second fastening outer end) in the radial direction within the contact surface (second pressing surface Ps2) between the second fastening portion 74 and the back surface 64a of the second flange portion 64. Then, among the first fastening outer end To1 and the second fastening outer end To2, the one located more inward in the radial direction is defined as the fastening outer end To0 (in this embodiment, the second fastening outer end To2 corresponds). In this case, in the fastening region (high fastening pressure region Rht) between the fastening inner end Ti0 and the fastening outer end To0 in the radial direction, the average value At2 of the axial thickness of the second flange portion 64 is smaller than the average value At1 of the axial thickness of the first flange portion 62 (At2 < At1). And the fastening inner end Ti0 is formed on the first flange portion 62. That is, the second fastening inner end Ti2 is located more radially inward than the first fastening inner end Ti1, and the second pressing surface Ps2 on the second fastening portion 74 side extends more radially inward than the first pressing surface Ps1 on the first fastening portion 72 side.

[0046] According to the present embodiment, since the average thickness At2 of the second flange portion 64 is smaller than the average thickness At1 of the first flange portion 62, when the fastening force of the fastening members 66 is applied to both flange portions 62 and 64, the second flange portion 64 is deformed more. Therefore, a radially uneven load is likely to be applied to the second seal surface S2 formed between the second flange portion 64 and the outer peripheral edge portion 68a of the heat shield plate 68. On the other hand, since the second pressure surface Ps2 on the second flange portion 64 side extends radially inward, the fastening force of the fastening members 66 is applied to a radially inner region than the first flange portion 62. Therefore, the radially uneven load applied to the second seal surface S2 on the second flange portion 64 side is canceled out, resulting in a substantially uniform load L2, and the sealing performance of the second seal surface S2 on the second flange portion 64 side is maintained.

[0047] On the other hand, in the first flange portion 62, the first pressure surface Ps1 does not extend to the radially inner region like the second pressure surface Ps2, and therefore the fastening force of the fastening member 66 does not reach the radially inner region like the second flange portion 64. Therefore, the first seal surface S1 is likely to be subjected to a non-uniform load in the radial direction. However, because the average thickness At1 of the first flange portion 62 is greater than the average thickness At2 of the second flange portion 64, the first seal surface S1 is less deformed than the second flange portion 64. Therefore, the first seal surface S1 on the first flange portion 62 side is not subjected to a significantly non-uniform load in the radial direction, and instead is subjected to a uniform load L1. Thus, the loads applied to the seal surfaces S1 and S2 on both the first flange portion 62 side and the second flange portion 64 are averaged in the radial direction, thereby maintaining sealing performance.

[0048] In the embodiment shown in Figure 8, the average thickness At1 of the first flange portion 62 is greater than the average thickness At2 of the second flange portion 64, and the fastening inner end Ti0 is located in the first flange portion 62, but in another embodiment, the average thickness At2 of the second flange portion 64 may be greater than the average thickness At1 of the first flange portion 62, and the fastening inner end Ti0 may be located in the second flange portion 64.

[0049] In one embodiment, as shown in FIG. 3, the radial distance Ra between the center of the rotating shaft 36 and the rear side tongue portion 58 and the radial distance Rb between the central axis O of the rotating shaft 36 and the inner end Si0 of the seal are configured to satisfy the relationship 1.1Ra≦Rb. According to this embodiment, each of the seal surfaces S1 and S2 is sufficiently spaced radially outward from the rear-side tongue portion 58, and is therefore substantially not affected by uneven thermal deformation of the rear-side tongue portion 58. As a result, the sealing performance of these seal surfaces S1 and S2 can be maintained.

[0050] 6 (first cross section), the turbine housing 42 includes an extension portion 90 that extends in the axial direction from the outer peripheral surface of the scroll portion 44 toward the first flange portion 62. In the first cross section, a thickness t1 of a minimum thickness portion 92, where the radial thickness of the extension portion 90 is smallest, and a distance t2 along the axial direction between the minimum thickness portion 92 and the first seal inner end Si1 are configured to satisfy the relationship t1≦t2. When a heat flux generated by heat transferred from the exhaust gas e to the turbine housing 42 flows through the extension portion 90, the heat flux with the highest density per unit area flows through the minimum thickness portion 92.

[0051] According to this embodiment, the first seal surface S1 satisfies the relationship t1≦t2 and is distant from the minimum thickness portion 92, so that the first seal surface S1 is less susceptible to the effects of non-uniform thermal deformation of the rear-side tongue portion 58. This allows the sealing performance of the first seal surface S1 to be maintained.

[0052] The contents described in each of the above embodiments can be understood, for example, as follows.

[0053] 1) An exhaust turbine according to one aspect includes a rotating shaft (36), a turbine wheel (40) attached to one end of the rotating shaft (36), a turbine housing (42) that accommodates the turbine wheel (40), the turbine housing (42) having a scroll portion (44) formed on an outer periphery of the turbine wheel (40) that introduces exhaust gas (e) into the turbine wheel (40), a bearing housing (38) that accommodates a bearing (52) that supports the rotating shaft (36), the bearing housing (38) being provided adjacent to the turbine housing (42), a fastening member (66) for fastening a first flange portion (62) of the turbine housing (42) to a second flange portion (64) of the bearing housing (38), and a heat shield plate disposed between the turbine housing (42) and the bearing housing (38), the outer periphery of the heat shield plate being in contact with the first flange portion (62). and a heat shield plate (68) sandwiched between the first flange portion (62) and the second flange portion (64), and in a first cross section along the axial direction of the rotating shaft (36) and passing through a center (O) of the rotating shaft (36) and a tongue portion (58) of the turbine housing (42), the innermost position in the radial direction of the rotating shaft (36) of an abutment surface (S1) between the first flange portion (62) and the outer peripheral edge portion (68a) of the heat shield plate (68) is defined as a first seal inner end (S i1), the innermost position in the radial direction of the abutment surface (S2) between the second flange portion (64) and the outer peripheral edge portion (68a) of the heat shield plate (68) is defined as the second seal inner end (Si2), and the one of the first seal inner end (Si1) and the second seal inner end (Si2) that is positioned outer in the radial direction is defined as the seal inner end (Si0), and the seal inner end (Si0) is positioned outer in the radial direction than the tongue portion (58).

[0054] According to this configuration, the seal inner end (Si0) of the first seal inner end (Si1) and the second seal inner end (Si2) that is located outward in the radial direction of the rotating shaft (36) (the inner end of the radial region where the seal surfaces (S1, S2) are formed on both sides of the outer peripheral edge portion (68a) of the heat shield plate (68) between the outer peripheral edge portion (68a) of the heat shield plate (68) and both flange portions (62, 64)) is located radially outward of the tongue portion (58). Therefore, the seal surfaces (S1, S2) are formed on both sides of the outer peripheral edge portion (68a) of the heat shield plate (68), and the radial region that exhibits the best sealing performance is located radially outward away from the part of the tongue portion (58) that is affected by non-uniform thermal deformation. This prevents the sealing surfaces (S1, S2) formed on the outer peripheral edge portion (68a) of the heat shield plate (68) from being affected by uneven thermal deformation of the tongue portion (58), thereby maintaining the sealing performance of the heat shield plate (68).

[0055] 2) An exhaust turbine according to another aspect is the exhaust turbine according to 1), wherein the fastening member (66) includes a base portion (70) arranged on an outer circumferential side of the first flange portion (62) and the second flange portion (64), a first fastening portion (72) extending from the base portion (70) toward the inside in the radial direction along a back surface (62 a) of the first flange portion (62), and a second fastening portion (74) extending from the base portion (70) toward the inside in the radial direction along a back surface (64 a) of the second flange portion (64), and in the first cross section, a first seal outer end (So1) is defined as a first seal outer end (So2), a second seal outer end (So3) is defined as a second seal outer end (So4), and a third seal outer end (So5) is defined as a fourth seal outer end (So6). When the outermost position in the radial direction is defined as the second seal outer end (So2), the one of the first seal outer end (So1) and the second seal outer end (So2) that is located radially inward is defined as the seal outer end (So0), the innermost position in the radial direction of the abutment surface (S1) between the first fastening portion (72) and the back surface (62a) of the first flange portion (62) is defined as the first fastening inner end (Ti1), the innermost position in the radial direction of the abutment surface (S2) between the second fastening portion (74) and the back surface (64a) of the second flange portion (64) is defined as the second fastening inner end (Ti2), and the one of the first fastening inner end (Ti1) and the second fastening inner end (Ti2) that is located radially outward is defined as the fastening inner end (Ti0), the seal outer end (So0) is positioned radially inward of the fastening inner end (Ti0).

[0056] According to this configuration, the outer seal end (So0) (the outer end of a radial region where the seal surfaces (S1, S2) are formed on both sides of the outer peripheral edge portion (68a) of the heat shield plate (68) between the outer peripheral edge portion (68a) of the heat shield plate (68) and both flange portions (62, 64)) is located radially inward of the inner fastening end (Ti0) (the inner end of a radial region where fastening forces are applied to both flange portions (62, 64) from both the first fastening portion (72) and the second fastening portion (74). Therefore, the seal region (Rhs) where the sealing performance of the heat shield plate (68) is maximized in the radial direction is located away from the region (Rht) where the flange portions (62, 64) receive the greatest fastening force from the fastening members (66). As a result, even if the fastening force of the fastening member (66) applied to both flange portions (62, 64) is uneven in the circumferential direction of the rotating shaft (36), the fastening force applied to the sealing area (Rhs) is less uneven in the circumferential direction, thereby ensuring the sealing performance of both seal surfaces (S1, S2).

[0057] 3) An exhaust turbine according to yet another aspect is an exhaust turbine as described in 1) or 2), wherein one of the first flange portion (62) and the second flange portion (64) is formed with at least one inner convex portion (80) that protrudes toward the other flange portion of the first flange portion (62) and the second flange portion (64) radially outward from the outer peripheral edge portion (68a) of the heat shield plate (68), and the other flange portion is formed with at least one outer convex portion (82) that abuts the outer peripheral surface (80a) of the inner convex portion (80) and its inner peripheral surface (82a) of the inner convex portion (82) radially outward from the inner convex portion (80).

[0058] According to this configuration, the inner convex portion (80) and the outer convex portion (82) are formed on the radially outer side of the outer peripheral edge portion (68a) of the heat shield plate (68), and the presence of these concave and convex portions can improve sealing performance, thereby improving sealing performance between the first flange portion (62) and the second flange portion (64). Furthermore, the inner convex portion (80) and the outer convex portion (82) position the turbine housing (42) and the bearing housing (38) in the radial direction, thereby preventing axial misalignment between these housings.

[0059] 4) An exhaust turbine according to yet another aspect is the exhaust turbine according to 3), wherein the at least one outer protrusion (82) is formed on the first flange portion (62).

[0060] According to this configuration, at least one outer protrusion (82) is formed on the first flange portion (62), and therefore, even if the outer protrusion (82) is thermally deformed by the heat of the exhaust gas (e), the bearing housing (38) is not affected by the thermal deformation of the outer protrusion (82). Therefore, the effect of the thermal deformation of the turbine housing (42) on the bearing housing (38) is reduced, and deterioration in the sealing performance of the seal surface (S2) formed by the second flange portion (64) on the bearing housing (38) side and the heat shield plate (68) is suppressed.

[0061] 5) An exhaust turbine according to yet another aspect is an exhaust turbine according to any one of 1) to 4), wherein, in the first cross section, the length of the abutment surface (S1) between the first flange portion (62) and the outer peripheral edge portion (68a) of the heat shield plate (68) is shorter than the length of the abutment surface (S2) between the second flange portion (64) and the outer peripheral edge portion (68a) of the heat shield plate (68).

[0062] With this configuration, the area of ​​the contact surface (S1) between the first flange portion (62) and the outer peripheral edge portion (68a) of the heat shield plate (68) is smaller than the area of ​​the contact surface (S2) between the second flange portion (64) and the outer peripheral edge portion (68a) of the heat shield plate (68). This reduces heat transfer from the first flange portion (62) to the bearing housing (38) via the outer peripheral edge portion (68a) of the heat shield plate (68). This reduces a temperature rise in the bearing housing (38) and thermal deformation of the bearing housing (38), thereby preventing a deterioration in the sealing performance between the heat shield plate (68) and the second flange portion (64). Furthermore, this reduces thermal stress generated in the bearing housing (38) due to a temperature rise, thereby improving the fatigue life of the bearing housing (38).

[0063] 6) An exhaust turbine according to still another aspect is the exhaust turbine according to 2), wherein, in the first cross section, the outermost position in the radial direction of an abutment surface (Ps1) between the first fastening portion (72) and the back surface (62a) of the first flange portion (62) is referred to as a first fastening outer end (To1), the outermost position in the radial direction of an abutment surface (Ps2) between the second fastening portion (74) and the back surface (64a) of the second flange portion (64) is referred to as a second fastening outer end (To2), and the innermost position in the radial direction of the first fastening outer end (To1) and the second fastening outer end (To2) is referred to as a is defined as an outer fastening end (To0), in the fastening region (Rht) between the inner fastening end (Ti0) and the outer fastening end (To0) in the radial direction, the average value (At) of the thickness in the axial direction (O) of one of the first flange portion (62) and the second flange portion (64) is smaller than the average value (At) of the thickness in the axial direction (O) of the other of the first flange portion (62) and the second flange portion (64), and the inner fastening end (Ti0) is formed on the other flange portion.

[0064] According to this configuration, in the fastening region (Rht) (a region where fastening forces are applied to the outer peripheral edge portion (68a) of the heat shield plate (68) from both the first fastening portion (72) and the second fastening portion (74) in the radial direction), the average axial thickness (At) of one of the first flange portion (62) and the second flange portion (64) is smaller than the average axial thickness (At) of the other flange portion. Therefore, the one flange portion is more deformed by the fastening force of the fastening member (66) than the other flange portion. Therefore, a non-uniform load is likely to be applied in the radial direction to the seal surface formed between the one flange portion and the outer peripheral edge portion (68a) of the heat shield plate (68). On the other hand, the fastening inner end (Ti0) is formed on the other flange portion, and therefore the fastening force applied to the one flange portion extends radially inward from the other flange portion. Therefore, the uneven radial load applied to the seal surface on one flange side is offset, and the sealing performance of the seal surface on one flange side is maintained.

[0065] In contrast, because the other flange portion has the inner fastening end (Ti0), the radially inner end of the region where the fastening force of the fastening member (66) acts on the other flange portion is located outside the radially inner end of the region where the fastening force of the fastening member (66) acts on the one flange portion. Therefore, the fastening member (66) is likely to apply a radially uneven load to the seal surface formed between the other flange portion and the outer peripheral edge portion (68a) of the heat shield plate (68). However, because the average axial thickness (At) of the other flange portion is greater than the average axial thickness (At) of the one flange portion, the other flange portion is less likely to deform due to the fastening force applied by the fastening member (66) than the one flange portion. Therefore, the sealing performance of the seal surface on the other flange portion side is ensured.

[0066] 7) An exhaust turbine according to yet another aspect is the exhaust turbine described in any one of 1) to 6), wherein, in the first cross section, the radial distance Ra between the center of the rotating shaft (36) and the tongue portion (58) and the radial distance Rb between the center (O) of the rotating shaft (36) and the seal inner end (Si0) satisfy the relationship 1.1Ra≦Rb.

[0067] According to this configuration, each of the sealing surfaces (S1, S2) formed between the first flange portion (62) and the second flange portion (64) and the outer peripheral edge portion (68a) of the heat shield plate (68) is located sufficiently far outward from the tongue portion (58) in the radial direction, and is therefore substantially not affected by uneven thermal deformation of the tongue portion (58), thereby maintaining the sealing performance of these sealing surfaces (S1, S2).

[0068] 8) An exhaust turbine according to yet another aspect is the exhaust turbine described in any one of 1) to 7), wherein the turbine housing (42) includes an extension portion (90) extending along the axial direction (O) from an outer peripheral surface of the scroll portion (44) toward the first flange portion (62), and in the first cross section, a thickness t1 of a minimum thickness portion (92) at which the thickness in the radial direction of the extension portion (90) is smallest, and a distance t2 along the axial direction (O) between the minimum thickness portion (92) and the first seal inner end (Si1) satisfy the relationship t1≦t2.

[0069] The heat flux generated in the turbine housing (42) due to heat transferred from the exhaust gas (e) to the turbine housing (42) has the highest density per unit area in the minimum thickness portion (92). According to the above configuration, the axial distance t2 between the minimum thickness portion (92) and the second seal inner end (Si2) is equal to or greater than the thickness t1 of the minimum thickness portion (92). Therefore, the seal surface (S1) formed between the first flange portion (62) and the outer peripheral edge portion (68a) of the heat shield plate (68) is less susceptible to the influence of non-uniform thermal deformation of the tongue portion (58), and therefore, sealing performance can be maintained.

[0070] 9) A turbocharger according to yet another aspect further includes the exhaust turbine (34) according to any one of 1) to 8), a compressor wheel (32b) attached to the other end of the rotating shaft (36) relative to the turbine wheel (40) via the bearing housing (38), and a compressor housing (32a) that houses the compressor wheel (32b).

[0071] According to this configuration, since the exhaust turbine (34) described in any one of 1) to 8) is provided, even if uneven thermal deformation occurs due to the heat of the exhaust gas (e) near the tongue portion (58) formed in the turbine housing (42) through which the exhaust gas (e) flows, the sealing performance of each of the sealing surfaces (S1, S2) formed between the first flange portion (62) of the turbine housing (42) and the heat shield plate (68) and between the second flange portion (64) of the bearing housing (38) and the heat shield plate (68) can be maintained at a high level. [Explanation of symbols]

[0072] 10 Engine 12a, 12b, 12c, 12d cylinders 14 Engine body 16 Air supply pipe 18 Air intake manifold 20 Exhaust manifold 22 Exhaust pipe 30 Supercharger 32 Compressor section 32a Compressor Housing 32b compressor wheel 34 (34a, 34b, 34c) Exhaust turbine section 36 Rotation axis 38 Bearing housing 40 Turbine Wheel 42 Turbine housing 44 Scroll section 45 Bulkhead 45a Bulkhead surface 46 Exhaust gas inlet 48 blades 50 Exhaust gas intake passage 52 Bearings 54 Rear exhaust gas flow path 56 Front exhaust gas flow path 54a Bulkhead surface 58 Rear tongue 59 Downstream end 60 Front tongue 62 First flange 62a back 64 Second flange 64a back 65 Convex part 65b End face 66(66a, 66b, 66c) Fastening member 68 Heat shield 68a Outer edge 70(70a, 70b) base 72 1st fastening part 74 Second fastening part 80 Inner convex part 80a Outer surface 82 Outer convex part 82a Inner surface 82b End face 90 Extension 92 Minimum thickness part L1, L2 load D. Underside of tongue M midpoint O center axis Ps1 First pressure surface Ps2 Second pressure surface Rhs high sealing pressure range Rht High fastening pressure area S1 First seal surface S2 Second seal surface Si1 First seal inner end Si2 Second seal inner end Si0 seal inner edge So1 Outer end of first seal So2 Second seal outer edge So0 Seal outer edge Ti1 1st fastening inner end Ti2 2nd fastening inner end Ti0 Fastening inner end Tn Tongue reference line To1 1st fastening outer end To2 2nd fastening outer end To0 Outer end of fastening a Fuel air

Claims

1. A rotation axis; a turbine wheel attached to one end of the rotary shaft; a turbine housing that accommodates the turbine wheel, the turbine housing having a scroll portion formed on an outer circumferential side of the turbine wheel that introduces exhaust gas into the turbine wheel; a bearing housing that accommodates a bearing that supports the rotary shaft, the bearing housing being provided adjacent to the turbine housing; a fastening member for fastening the first flange portion of the turbine housing and the second flange portion of the bearing housing together; a single heat shield plate disposed between the turbine housing and the bearing housing, the outer peripheral edge of the heat shield plate being sandwiched between the first flange portion and the second flange portion; in a first cross section along the axial direction of the rotating shaft, the first cross section passing through the center of the rotating shaft and the tongue portion of the turbine housing, the innermost position in the radial direction of the rotating shaft of the abutment surface between the first flange portion and the outer peripheral edge portion of the heat shield plate is defined as a first seal inner end, the innermost position in the radial direction of the rotating shaft of the abutment surface between the second flange portion and the outer peripheral edge portion of the heat shield plate is defined as a second seal inner end, and the one of the first seal inner end and the second seal inner end that is positioned outer in the radial direction is defined as a seal inner end, the outer peripheral edge portion of the heat shield plate includes a first surface that abuts against the first flange portion, and a second surface that is opposite to the first surface and abuts against the second flange portion, In the first cross section, a length of a contact surface between the first flange portion and the first surface of the heat shield plate is shorter than a length of a contact surface between the second flange portion and the second surface of the heat shield plate, and The front surface of the first flange portion on the second flange side includes, inward in the radial direction from the inner end of the first seal, a flat surface facing the first surface of the heat shield plate with a predetermined gap therebetween, and a curved surface that is concave toward the side opposite the heat shield plate and connects the outermost position of the flat surface in the radial direction to the inner end of the first seal. Exhaust turbine.

2. The fastening member is a base portion disposed on an outer circumferential side of the first flange portion and the second flange portion; a first fastening portion extending from the base portion toward an inner side in the radial direction along a back surface of the first flange portion; a second fastening portion extending from the base portion toward the inside in the radial direction along a back surface of the second flange portion, In the first cross section, the outermost position in the radial direction of the contact surface between the first flange portion and the outer peripheral edge portion of the heat shield plate is defined as a first seal outer end, the outermost position in the radial direction of the contact surface between the second flange portion and the outer peripheral edge portion of the heat shield plate is defined as a second seal outer end, and the one of the first seal outer end and the second seal outer end that is located on the inner side in the radial direction is defined as a seal outer end, When the innermost position in the radial direction of the contact surface between the first fastening portion and the back surface of the first flange portion is defined as a first fastening inner end, the innermost position in the radial direction of the contact surface between the second fastening portion and the back surface of the second flange portion is defined as a second fastening inner end, and the one of the first fastening inner end and the second fastening inner end that is positioned outward in the radial direction is defined as a fastening inner end, the seal outer end is disposed radially inward of the fastening inner end; The exhaust turbine of claim 1 .

3. At least one inner convex portion is formed on one of the first flange portion and the second flange portion, outside the outer peripheral edge portion of the heat shield plate in the radial direction, protruding toward the other of the first flange portion and the second flange portion, and at least one outer convex portion is formed on the other flange portion, outside the inner convex portion in the radial direction, the outer peripheral surface of which abuts against the inner peripheral surface of the inner convex portion. An exhaust turbine according to claim 1 or 2.

4. the at least one outer protrusion is formed on the first flange portion; 4. The exhaust turbine according to claim 3.

5. In the first cross section, when the outermost position in the radial direction of the contact surface between the first fastening portion and the back surface of the first flange portion is defined as a first fastening outer end, the outermost position in the radial direction of the contact surface between the second fastening portion and the back surface of the second flange portion is defined as a second fastening outer end, and the one of the first fastening outer end and the second fastening outer end that is located inner in the radial direction is defined as a fastening outer end, In a fastening region between the fastening inner end and the fastening outer end in the radial direction, an average value of a thickness of one of the first flange portion and the second flange portion in the axial direction is smaller than an average value of a thickness of the other of the first flange portion and the second flange portion in the axial direction, and The fastening inner end is formed on the other flange portion. The exhaust turbine of claim 2.

6. In the first cross section, the radial distance Ra between the center of the rotating shaft and the tongue portion and the radial distance Rb between the center of the rotating shaft and the seal inner end satisfy the relationship 1.1Ra≦Rb. An exhaust turbine according to any one of claims 1 to 5.

7. the turbine housing includes an extension portion extending along the axial direction from an outer peripheral surface of the scroll portion toward the first flange portion, In the first cross section, a thickness t1 of a minimum thickness portion where the thickness in the radial direction of the extension portion is smallest, and a distance t2 along the axial direction between the minimum thickness portion and an inner end of the first seal satisfy a relationship of t1≦t2. An exhaust turbine according to any one of claims 1 to 6.

8. An exhaust turbine according to any one of claims 1 to 7; a compressor wheel attached to the other end side of the rotary shaft relative to the turbine wheel via the bearing housing; a compressor housing that houses the compressor wheel, Supercharger.

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