Turbocharger

Abstract

The present invention provides a turbocharger, including a turbine housing and an exhaust gas bypass valve. The turbine housing defines two bypass passages. The exhaust gas bypass valve opens and closes the two bypass passages. The turbine housing has a valve seat surface on a plane that contacts the exhaust gas bypass valve. The exhaust gas bypass valve has a valve surface and a recess. The valve surface is a plane that faces the valve seat surface when the exhaust gas bypass valve is in the closed state. The recess is recessed relative to the valve surface. The recess is located at a position opposite to the area sandwiched by the openings of the two bypass passages when the exhaust gas bypass valve is in the closed state.

Description

Technical Field

[0001] The present invention relates to a turbocharger. Background Art

[0002] The turbocharger described in Japanese Unexamined Patent Application Publication No. 2020-084923 includes a turbine impeller, a turbine housing, and an exhaust gas bypass valve. The turbine housing houses the turbine impeller. The turbine housing defines two bypass passages. Each bypass passage bypasses the upstream side and the downstream side of the exhaust gas with respect to the turbine impeller. The turbine housing has a valve seat surface on a plane that contacts the exhaust gas bypass valve when the exhaust gas bypass valve is in the closed state. On the other hand, the exhaust gas bypass valve has a valve surface on a plane that faces the valve seat surface when the exhaust gas bypass valve is in the closed state. Summary of the Invention

[0003] In a turbocharger such as that described in Japanese Unexamined Patent Application Publication No. 2020-084923, the periphery of the valve seat surface of the turbine housing is heated by the exhaust gas flowing through the two bypass passages. When the periphery of the valve seat surface is heated and thermally expanded, the valve seat surface is deformed. Therefore, when the exhaust gas bypass valve is in the closed state, the valve seat surface and the valve surface may not be properly contacted.

[0004] A turbocharger for solving the above problems includes: a turbine impeller that rotates by the flow of exhaust gas; a turbine housing that houses the turbine impeller and defines a plurality of bypass passages that bypass the upstream side and the downstream side of the exhaust gas with respect to the turbine impeller; and an exhaust gas bypass valve that opens and closes the plurality of bypass passages. The turbine housing has a flat valve seat surface that contacts the exhaust gas bypass valve when the exhaust gas bypass valve is in the closed state. The exhaust gas bypass valve has: a flat valve surface that faces the valve seat surface when the exhaust gas bypass valve is in the closed state; and a concave portion that is recessed with respect to the valve surface. The concave portion is located at a position facing a region of the inner surface of the turbine housing that is sandwiched by the openings of the plurality of bypass passages when the exhaust gas bypass valve is in the closed state.

[0005] In the above structure, the concave portion exists at a position facing a region of the valve seat surface that is sandwiched by the plurality of bypass passages and is particularly susceptible to the heating effect of the exhaust gas. Therefore, according to the above structure, even if the valve seat surface expands due to the heating effect of the exhaust gas, the expanded portion will be received in the concave portion of the exhaust gas bypass valve, and thus it is not likely to contact the exhaust gas bypass valve. Therefore, when the exhaust gas bypass valve is in the closed state, the valve seat surface and the valve surface can be properly contacted.

[0006] In the above structure, the following method may also be adopted, that is, when drawing an imaginary straight line connecting the opening centers of adjacent bypass passages, the recess is located at a position opposite to the imaginary straight line when the exhaust gas bypass valve is in the closed state.

[0007] According to the above structure, the position of the recess corresponds to the portion in the valve seat surface that is most susceptible to the heating effect of the exhaust gas flowing in the adjacent bypass passages, that is, the portion where the most expansion is assumed to occur. Therefore, the situation where the expanded portion in the valve seat surface contacts the exhaust gas bypass valve can be appropriately suppressed.

[0008] The turbocharger for solving the above problems includes: a turbine impeller that rotates by the flow of exhaust gas; a turbine housing that houses the turbine impeller and defines a plurality of bypass passages that bypass the upstream side and the downstream side of the exhaust gas relative to the turbine impeller; and an exhaust gas bypass valve that opens and closes the plurality of bypass passages. The turbine housing has: a planar valve seat surface that contacts the exhaust gas bypass valve when the exhaust gas bypass valve is in the closed state; and a recess that is recessed relative to the valve seat surface. The exhaust gas bypass valve has a planar valve surface that faces the valve seat surface when the exhaust gas bypass valve is in the closed state. The recess is located in the region of the inner surface of the turbine housing that is sandwiched by the openings of the plurality of bypass passages.

[0009] In the above structure, the recess exists in the region of the turbine housing that is sandwiched by the plurality of bypass passages and is particularly susceptible to the heating effect of the exhaust gas. Therefore, according to the above structure, even if the turbine housing expands due to the heating effect of the exhaust gas, the situation where the exhaust gas bypass valve contacts the portion of the turbine housing that is sandwiched by the plurality of bypass passages can be suppressed. Therefore, when the exhaust gas bypass valve is in the closed state, the valve seat surface and the valve surface can be appropriately contacted.

[0010] In the above structure, the following method may also be adopted, that is, the recess is located in the entire region of the region.

[0011] According to the above structure, the recess exists in the entire region of the portion where the degree of expansion caused by heating is large. Therefore, even if the peripheries of the bypass passages of the turbine housing expand, the appropriate contact between the valve seat surface and the valve surface can be ensured.

[0012] In the above structure, the following method may also be adopted, that is, the turbine housing has a through hole that penetrates the wall of the turbine housing. The exhaust gas bypass valve has: a shaft that penetrates the through hole and is rotatably supported by the turbine housing; and a valve core that extends radially from the end portion of the shaft on the inner side of the turbine housing. The shaft and the valve core are integrally formed.

[0013] In the above-described exhaust gas bypass valve, since the valve element does not swing relative to the shaft, the valve surface cannot conform to the valve seat surface when the valve seat surface expands. It is particularly effective to adopt a structure related to the concave portion in a turbocharger equipped with such an exhaust gas bypass valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Hereinafter, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the drawings, in which the same reference numerals denote the same elements, and in which:

[0015] Figure 1 is a schematic diagram of an internal combustion engine.

[0016] Figure 2 is a cross-sectional view showing the peripheral structure of the turbine housing.

[0017] Figure 3 is a cross-sectional view showing the peripheral structure of the exhaust gas bypass valve.

[0018] Figure 4 is a bottom view of the exhaust gas bypass valve.

[0019] Figure 5 is a cross-sectional view showing the peripheral structure of the exhaust gas bypass valve.

[0020] Figure 6 is an explanatory view showing the peripheral structure of the exhaust gas bypass valve.

[0021] Figure 7 is a top view showing the peripheral structure of the valve seat surface according to a modified example. DETAILED DESCRIPTION

[0022] <Schematic Structure of Internal Combustion Engine>

[0023] Hereinafter, according to Figures 1 to 6 an embodiment of the present invention will be described. First, the schematic structure of an internal combustion engine 10 of a vehicle to which a turbocharger 20 of the present invention is applied will be described.

[0024] As Figure 1 shown, the internal combustion engine 10 includes an intake passage 11, a cylinder 12, an exhaust passage 13, a catalyst 15, and a turbocharger 20. The intake passage 11 introduces intake air from outside the internal combustion engine 10. The cylinder 12 is connected to the intake passage 11. The cylinder 12 mixes fuel with the intake air and burns it. The exhaust passage 13 is connected to the cylinder 12. The exhaust passage 13 discharges the exhaust gas from the cylinder 12. The catalyst 15 is located in the middle of the exhaust passage 13. The catalyst 15 purifies the exhaust gas flowing in the exhaust passage 13.

[0025] The turbocharger 20 includes a compressor housing 30, a bearing housing 50, a turbine housing 60, a compressor impeller 70, a connecting shaft 80, and a turbine impeller 90.

[0026] The compressor housing 30 is installed in the middle of the intake passage 11. The turbine housing 60 is installed at a portion upstream of the catalyst 15 in the exhaust passage 13. The bearing housing 50 is fixed to the compressor housing 30 and the turbine housing 60 respectively, and connects the compressor housing 30 and the turbine housing 60. In this way, the turbocharger 20 is disposed across the intake passage 11 and the exhaust passage 13.

[0027] The turbine housing 60 houses the turbine impeller 90. The bearing housing 50 houses the connecting shaft 80. The bearing housing 50 rotatably supports the connecting shaft 80 via a bearing (not shown). The first end of the connecting shaft 80 is connected to the turbine impeller 90. The compressor housing 30 houses the compressor impeller 70. The compressor impeller 70 is connected to the second end of the connecting shaft 80. That is, the compressor impeller 70 is connected to the turbine impeller 90 via the connecting shaft 80.

[0028] When the turbine impeller 90 rotates by the flow of the exhaust gas inside the turbine housing 60, the compressor impeller 70 rotates together via the connecting shaft 80. And, by the rotation of the compressor impeller 70, the intake gas inside the compressor housing 30 is compressed.

[0029] <Structure of Turbocharger>

[0030] Next, the specific structure of the turbocharger 20 will be described.

[0031] As Figure 2 shown, the turbine housing 60 includes an arc portion 60A, a cylindrical portion 60B, and a flange portion 60C. The cylindrical portion 60B has a substantially cylindrical shape. The cylindrical portion 60B extends substantially along the rotation axis 90A which is the rotation center of the turbine impeller 90. The arc portion 60A extends so as to surround the outer periphery of the cylindrical portion 60B, and has a substantially arc shape. The flange portion 60C is located at the upstream end of the arc portion 60A. The flange portion 60C is fixed to a portion of the exhaust passage 13 upstream of the turbine housing 60.

[0032] As Figure 2 shown, the turbine housing 60 defines two vortex passages 61, a housing space 62, a discharge passage 63, and two bypass passages 64 as spaces for the exhaust gas to flow through. In addition, in Figure 2In the figure, a bypass passage 64 is illustrated. Each vortex passage 61 is located inside the arc portion 60A and the cylindrical portion 60B. The vortex passage 61 extends in an arc shape so as to surround the turbine impeller 90. The upstream end of the vortex passage 61 is connected to the exhaust passage 13 at a position upstream of the turbine housing 60. The downstream end of the vortex passage 61 is connected to the accommodation space 62. The two vortex passages 61 extend substantially parallel to each other. The accommodation space 62 is the space where the turbine impeller 90 is located in the inner space of the cylindrical portion 60B. The accommodation space 62 is connected to the discharge passage 63. The discharge passage 63 is a part of the space in the inner space of the cylindrical portion 60B that includes the end on the side opposite to the bearing housing 50, that is Figure 2 the upper end part in

[0033] As Figure 3 shown, the turbine housing 60 includes a valve seat surface 66 and a through hole 69. The valve seat surface 66 is a plane on the inner wall surface of the turbine housing 60 that divides the discharge passage 63 and surrounds the opening edges of the two bypass passages 64. That is, each bypass passage 64 opens on the valve seat surface 66. The part of the inner surface of the turbine housing 60 that includes the valve seat surface 66 bulges relative to other parts. As Figure 6 shown by the double-dot dash line in

[0034] As Figure 3 shown, the through hole 69 penetrates the wall of the turbine housing 60. The through hole 69 is located in the part of the wall of the turbine housing 60 that divides the discharge passage 63. The central axis 69A of the through hole 69 is parallel to the valve seat surface 66. In addition, the central axis 69A of the through hole 69 extends in the direction in which two adjacent bypass passages 64 are arranged side by side, that is Figure 3 the left-right direction in

[0035] As Figure 1 and Figure 3 shown, the turbocharger 20 includes an exhaust gas bypass valve 110, a bushing 120, a link mechanism 130, and an actuator 140. As Figure 3As shown, the shape of the bushing 120 is a substantially cylindrical shape. The outer diameter of the bushing 120 is substantially the same as the inner diameter of the through hole 69. The bushing 120 is located inside the through hole 69.

[0036] As Figure 3 shown, the exhaust gas bypass valve 110 includes a shaft 111 and a valve element 112. The shape of the shaft 111 is a substantially cylindrical shape. The outer diameter of the shaft 111 is substantially the same as the inner diameter of the bushing 120. The shaft 111 is inserted through the bushing 120. That is, the shaft 111 passes through the through hole 69 of the turbine housing 60. The turbine housing 60 supports the shaft 111 rotatably via the bushing 120. In addition, the central axis 111A of the shaft 111 coincides with the central axis 69A of the through hole 69.

[0037] As Figure 4 shown, the valve element 112 has a connecting portion 113 and a valve body 114. The connecting portion 113 extends from the shaft 111 in the radial direction of the shaft 111. As Figure 3 shown, the connecting portion 113 is located at the end of the shaft 111 on the inner side of the turbine housing 60, that is, Figure 3 the right end of the shaft 111 in Figure 3 shown. As Figure 4 shown, the valve body 114 is connected to the end of the connecting portion 113 on the radially outer side of the shaft 111. As Figure 4 shown, the shape of the valve body 114 is a substantially circular plate shape. In addition, the surface of the valve body 114 opposite to the connecting portion 113, that is,

[0038] the surface near the paper surface in Figure 3 functions as a valve surface 116. The valve surface 116 is a flat surface. The valve surface 116 faces the valve seat surface 66 when the exhaust gas bypass valve 110 is in the closed state. The exhaust gas bypass valve 110 is an integrally formed object obtained by integrally forming the shaft 111 and the valve element 112. In addition, the exhaust gas bypass valve 110 is integrally formed by casting, for example. Figure 1 shown, the link mechanism 130 is connected to the end of the shaft 111 on the outer side of the turbine housing 60. As

[0039] Specifically, when the exhaust gas bypass valve 110 changes from the open state to the closed state, the driving force of the actuator 140 is transmitted to the shaft 111 via the link mechanism 130, whereby the shaft 111 rotates relative to the turbine housing 60 in the first rotational direction in the circumferential direction of the shaft 111. Then, the valve surface 116 of the exhaust gas bypass valve 110 contacts the valve seat surface 66 of the turbine housing 60. Therefore, when the exhaust gas bypass valve 110 is in the closed state, the valve surface 116 of the exhaust gas bypass valve 110 faces the valve seat surface 66 of the turbine housing 60, whereby the downstream end of the bypass passage 64 is covered by the valve surface 116 of the exhaust gas bypass valve 110. In addition, in the present embodiment, the state in which the valve surface 116 of the exhaust gas bypass valve 110 contacts the valve seat surface 66 of the turbine housing 60 and the exhaust gas bypass valve 110 cannot further rotate toward the closed side is the closed state.

[0040] On the other hand, when the exhaust gas bypass valve 110 changes from the closed state to the open state, the driving force of the actuator 140 is transmitted to the shaft 111 via the link mechanism 130, whereby the shaft 111 rotates relative to the turbine housing 60 in the second rotational direction in the circumferential direction of the shaft 111. Then, the valve surface 116 of the exhaust gas bypass valve 110 separates from the valve seat surface 66 of the turbine housing 60. Therefore, when the exhaust gas bypass valve 110 is in the open state, the downstream end of the bypass passage 64 is not covered by the valve surface 116 of the exhaust gas bypass valve 110.

[0041] <Structure of the recess>

[0042] Next, the recess 117 of the exhaust gas bypass valve 110 will be described.

[0043] Hereinafter, as Figure 6 shown, the region of the inner surface of the turbine housing 60 that is sandwiched by the openings of the two bypass passages 64 on the valve seat surface 66 is referred to as region 60Z. In addition, the center of the opening of one of the two adjacent bypass passages 64 on the valve seat surface 66 is referred to as center 64A, and the center of the opening of the other of the two adjacent bypass passages 64 on the valve seat surface 66 is referred to as center 64B. Moreover, the imaginary straight line connecting center 64A and center 64B to each other is referred to as imaginary straight line 64Z. In addition, the center of the opening means the geometric center of the opening shape when viewed from a direction orthogonal to the valve seat surface 66.

[0044] As Figure 6 shown, when viewed from a direction orthogonal to the valve seat surface 66, region 60Z extends in the direction orthogonal to the central axis 69A of the through hole 69, that is, Figure 6 the up-and-down direction in Figure 6The dimension in the left - right direction is substantially constant. In addition, the dimension in the width direction of the portion including the end portion in the length direction of the region 60Z becomes larger as it approaches the end portion in the length direction.

[0045] As Figure 5 shown, the valve body 114 of the exhaust gas bypass valve 110 has a recess 117. The recess 117 is recessed from the valve face 116. The depth of the recess 117 is constant throughout. An example of the depth of the recess 117 is about 2 - 3 mm. As Figure 4 shown, the recess 117 is located approximately at the center of the valve face 116. When viewed from a direction orthogonal to the valve face 116, the recess 117 extends in the direction orthogonal to the central axis 111A of the shaft 111, that is, Figure 4 in the up - down direction in Figure 6 shown. When viewed from a direction orthogonal to the valve face 116, the shape of the recess 117 is approximately rectangular. As

[0046] As Figure 6 shown, when the exhaust gas bypass valve 110 is in the closed state, when viewed from a direction orthogonal to the valve seat face 66, the center of the recess 117 coincides with the center of the region 60Z. That is, when the exhaust gas bypass valve 110 is in the closed state, the recess 117 is located at a position opposite to the region 60Z. In addition, when the exhaust gas bypass valve 110 is in the closed state, the recess 117 is located at a position opposite to the imaginary straight line 64Z. Thus, the recess 117 has a size and position that faces most of the region 60Z when the exhaust gas bypass valve 110 is in the closed state.

[0047] <Function of the present embodiment>

[0048] In the turbocharger 20, when the exhaust gas bypass valve 110 is in the open state, the exhaust gas flows through the two bypass passages 64. When the exhaust gas flows through the bypass passage 64 as described above, since the heat of the exhaust gas is transferred, the periphery of the valve seat face 66 in the wall of the turbine housing 60 is heated. At this time, the region 60Z of the valve seat face 66 is sandwiched by the two bypass passages 64 and is particularly susceptible to the heat of the exhaust gas. As a result, the region 60Z of the valve seat face 66 sometimes expands significantly and protrudes relative to other parts of the valve seat face 66.

[0049] <Effect of the present embodiment>

[0050] (1) In the present embodiment, when the exhaust gas bypass valve 110 is in the closed state, the concave portion 117 of the exhaust gas bypass valve 110 is located at a position opposite to the region 60Z of the valve seat surface 66. Therefore, even if the region 60Z of the valve seat surface 66 expands due to the influence of the exhaust gas flowing in the two bypass passages 64, the expanded portion will be received in the concave portion 117. Therefore, when the exhaust gas bypass valve 110 is in the closed state, the valve surface 116 can be properly brought into contact with the valve seat surface 66.

[0051] (2) The portion of the region 60Z of the valve seat surface 66 located on the imaginary straight line 64Z is most easily affected by the heating of the exhaust gas flowing in the two bypass passages 64. Therefore, the portion of the region 60Z of the valve seat surface 66 located on the imaginary straight line 64Z is assumed to have the largest amount of expansion.

[0052] In the present embodiment, when the exhaust gas bypass valve 110 is in the closed state, the concave portion 117 is also particularly located at a position opposite to the imaginary straight line 64Z in the region 60Z. In this way, by providing the concave portion 117 corresponding to the portion of the valve seat surface 66 where the most expansion is assumed to occur, the situation where the expanded portion of the valve seat surface 66 comes into contact with the exhaust gas bypass valve 110 can be appropriately suppressed.

[0053] (3) In the present embodiment, the exhaust gas bypass valve 110 is an integrally formed product obtained by integrally forming the shaft 111 and the valve element 112. Therefore, in the exhaust gas bypass valve 110, since the valve element 112 does not swing relative to the shaft 111, when the valve seat surface 66 expands, the valve surface 116 cannot conform to the valve seat surface 66. Therefore, it is particularly effective to adopt the structure related to the concave portion 117 in the turbocharger 20 provided with such an exhaust gas bypass valve 110.

[0054] <Modified Example>

[0055] The present embodiment can be modified and implemented in the following manner. The present embodiment and the following modified examples can be implemented in combination with each other within the range where there is no technical contradiction.

[0056] "Regarding the Concave Portion"

[0057] · In the above embodiment, the number of the concave portions 117 can be changed. For example, the exhaust gas bypass valve 110 can be provided with a plurality of concave portions 117. As long as it is a position opposite to the region 60Z, the concave portion 117 can be one or more.

[0058] ·In the above-described embodiment, the position of the recess can be changed. For example, as long as it is a portion facing the region 60Z, the recess 117 may not be located at a portion facing the imaginary straight line 64Z. For example, the recess 117 may be located at a portion facing the end portion in the longitudinal direction of the region 60Z. In addition, the recess 117 is preferably located at a portion facing the portion in the region 60Z of the valve seat surface 66 where the amount of expansion is the largest.

[0059] ·Instead of or in addition to the recess 117 of the exhaust gas bypass valve 110, a recess 67 may be provided in the turbine housing 60. In Figure 7 the example shown, the turbine housing 60 includes a recess 67. The recess 67 is recessed from the valve seat surface 66. The recess 67 is located in the entire region of the region 60Z.

[0060] In this structure, the recess 67 exists in the region 60Z of the turbine housing 60 that is sandwiched by the two bypass passages 64 and is particularly susceptible to the influence of exhaust gas heating. Therefore, according to this structure, even if the region 60Z in the turbine housing 60 expands due to the influence of exhaust gas heating, it is possible to suppress contact between the exhaust gas bypass valve 110 and the region 60Z. Therefore, when the exhaust gas bypass valve 110 is in the closed state, it is possible to appropriately bring the valve seat surface 66 into contact with the valve surface 116. Moreover, the recess exists in the entire region of the region 60Z where the degree of expansion due to heating is large. Therefore, even if the periphery of each bypass passage 64 of the turbine housing 60 expands, it is possible to ensure appropriate contact between the valve seat surface 66 and the valve surface 116.

[0061] ·In Figure 7 the modified example shown, the recess 67 may not be located in the entire region of the region 60Z. For example, the recess 67 may be provided in the central portion in the longitudinal direction or the end portion in the longitudinal direction in the region 60Z. Even with these structures, when the region 60Z expands, it is possible to suppress the case where the exhaust gas bypass valve 110 comes into contact with the region 60Z. In addition, similar to the above-described recess 117, the recess 67 is preferably provided at a portion in the region 60Z where the amount of expansion is assumed to be the largest.

[0062] "Regarding the bypass passage"

[0063] ·In the above-described embodiment, the shape of the bypass passage 64 can also be changed.

[0064] · In the above-described embodiment, the number of bypass passages 64 may also be three or more. In this case, the recess 117 only needs to be located at a position facing the region sandwiched by the openings on the valve seat surface 66 of two adjacent bypass passages 64 among the three or more bypass passages 64. Similarly, the recess 67 only needs to be located in the region sandwiched by the openings on the valve seat surface 66 of two adjacent bypass passages 64 among the three or more bypass passages 64.

[0065] "Regarding other structures"

[0066] · In the above-described embodiment, the exhaust gas bypass valve 110 may not be an integrally formed product obtained by integrally forming the shaft 111 and the valve element 112. For example, the exhaust gas bypass valve 110 may be such that the valve element 112 can swing relative to the shaft 111.

Claims

1. A turbocharger, comprising: A turbine impeller that rotates by the flow of exhaust gas; A turbine housing that houses the turbine impeller and defines a plurality of bypass passages that bypass the upstream side and the downstream side of the exhaust gas relative to the turbine impeller; and An exhaust gas bypass valve that opens and closes the plurality of bypass passages, wherein The turbine housing has a planar valve seat surface that contacts the exhaust gas bypass valve when the exhaust gas bypass valve is in the closed state, The exhaust gas bypass valve has: a planar valve surface that faces the valve seat surface when the exhaust gas bypass valve is in the closed state; and a recess that is recessed relative to the valve surface, The recess is provided only at a portion facing the end portion in the longitudinal direction of the region of the inner surface of the turbine housing that is sandwiched by the openings of the plurality of bypass passages when the exhaust gas bypass valve is in the closed state, and is not provided at a portion facing the central portion in the longitudinal direction of the region, The region is affected by the heating of the exhaust gas flowing through the bypass passage and expands, and the expanded portion is received in the recess to prevent the exhaust gas bypass valve from contacting the region.

2. A turbocharger, comprising: A turbine impeller that rotates by the flow of exhaust gas; A turbine housing that houses the turbine impeller and defines a plurality of bypass passages that bypass the upstream side and the downstream side of the exhaust gas relative to the turbine impeller; and An exhaust gas bypass valve that opens and closes the plurality of bypass passages, wherein The turbine housing has: a planar valve seat surface that contacts the exhaust gas bypass valve when the exhaust gas bypass valve is in the closed state; and a recess that is recessed relative to the valve seat surface, The exhaust gas bypass valve has a planar valve surface that faces the valve seat surface when the exhaust gas bypass valve is in the closed state, The recess is provided only at a portion of the end portion in the longitudinal direction of the region of the inner surface of the turbine housing that is sandwiched by the openings of the plurality of bypass passages, and is not provided at the central portion in the longitudinal direction of the region, The region is affected by the heating of the exhaust gas flowing through the bypass passage and expands, and the recess prevents the exhaust gas bypass valve from contacting the region.

3. The turbocharger according to claim 1 or 2, wherein The turbine housing has a through hole that penetrates the wall of the turbine housing, The exhaust gas bypass valve has: a shaft that penetrates the through hole and is rotatably supported by the turbine housing; And a valve core that extends radially from the end portion of the shaft on the inner side of the turbine housing, The shaft and the valve core are integrally formed.

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