A turbocharger includes a turbine housing and a wastegate. The turbine housing has an accommodation space, is which a turbine wheel is accommodated. The accommodation space is connected to a scroll passage, which draws exhaust gas from the outside of the turbine housing, and a connection passage, which discharges exhaust gas from the accommodation space. The connection passage is connected to a merging passage, which discharges exhaust gas to the outside of the turbine housing. The merging passage is connected to a bypass passage, which bypasses the accommodation space. The central axis of an outlet portion of the connection passage is inclined with respect to the rotation axis of the turbine wheel toward the side on which an outlet portion of the bypass passage is located.

BACKGROUND

The present disclosure relates to a turbocharger.

The turbine housing in the turbocharger disclosed in Japanese Laid-Open Patent Publication No. 2017-082762 is provided with an accommodation space that accommodates a turbine wheel. This accommodation space is connected to a scroll passage, which draws exhaust gas from the outside of the turbine housing to the accommodation space. The accommodation space is also connected to a connection passage, which discharges exhaust gas from the accommodation space. The connection passage extends along the rotation axis of the turbine wheel. A section of the connection passage on the downstream side in the exhaust flow direction is connected to a merging passage, which discharges exhaust gas from the inside of the turbine housing. In addition, the turbine housing has a bypass passage extending from the scroll passage to the merging passage while bypassing the accommodation space.

The turbocharger of the above publication includes a wastegate, which has a pivot shaft pivotally supported by the turbine housing. A first valve member is fixed to the pivot shaft of the wastegate. Also, a second valve member is fixed to the pivot shaft of the wastegate to be separated from the first valve member in the circumferential direction about the pivot axis of the pivot shaft. When the pivot shaft pivots to one side, the first valve member closes the outlet portion of the connection passage. When the pivot shaft pivots to the other side, the second valve member closes the outlet portion of the bypass passage.

The turbine housing of the turbocharger disclosed of the above publication has a first sealing surface at the outlet portion of the connection passage. The first sealing surface is inclined with respect to a plane orthogonal to the central axis of the outlet portion of the connection passage to face the outlet portion of the bypass passage.

In the turbocharger disclosed in the above publication, the angle by which the first sealing surface is inclined with respect to the second sealing surface, which faces the second valve member at the outlet portion of the bypass passage, is smaller than that in a case in which the first sealing surface is orthogonal to the central axis of the outlet portion of the connection passage. This reduces the pivoting range of the wastegate from the state in which the first valve member of the wastegate is in contact with the first sealing surface to the state in which the second valve member is in contact with the second sealing surface.

In the turbocharger of the above publication, the first sealing surface is inclined as if cut obliquely. Therefore, the opening area of the outlet portion of the connection passage is larger than that in other cases. Accordingly, in the turbocharger of the above publication, the first valve member of the wastegate is relatively large in order to close the outlet portion of the connection passage. Therefore, the turbocharger of the above publication has room for further improvement in terms of miniaturization of the wastegate.

SUMMARY

In accordance with one aspect of the present disclosure, a turbocharger is provided that includes a turbine housing, which accommodates a turbine wheel, and a wastegate, which is rotationally supported by the turbine housing. The turbine housing includes an accommodation space, in which the turbine wheel is accommodated, a scroll passage, which is connected to the accommodation space and is configured to draw exhaust gas from outside of the turbine housing to the accommodation space, a connection passage, which is connected to the accommodation space and is configured to discharge exhaust gas from the accommodation space, a merging passage, which is connected to the connection passage and is configured to discharge exhaust gas to the outside of the turbine housing, and a bypass passage, which bypasses the accommodation space and is connected to the merging passage. The connection passage has an outlet portion that is connected to the merging passage. The bypass passage has an outlet portion that is connected to the merging passage. The wastegate includes a pivot shaft, which is pivotally supported by the turbine housing, a first valve member, which is fixed to the pivot shaft and is configured to close the outlet portion of the connection passage, and a second valve member, which is fixed to the pivot shaft to be separated from the first valve member in a circumferential direction about a pivot axis of the pivot shaft, the second valve member being configured to close the outlet portion of the bypass passage. A central axis of the outlet portion of the connection passage is inclined with respect to a rotation axis of the turbine wheel toward a side on which the outlet portion of the bypass passage is located.

Other aspects and advantages of the present disclosure will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating exemplary embodiments.

DETAILED DESCRIPTION

One embodiment of the present disclosure will now be described with reference toFIGS. 1 to 3. First, a schematic configuration of an internal combustion engine100equipped with a turbocharger50of the present embodiment will be described.

As shown inFIG. 1the internal combustion engine100has an intake passage11configured to draw in intake air from the outside of the engine100. The intake passage11is connected to a cylinder12, which mixes fuel with the intake air and burns the mixture. The cylinder12is connected to an exhaust passage13configured to discharge the exhaust gas from the cylinder12. The exhaust passage13incorporates a catalyst21, which purifies exhaust gas.

The internal combustion engine100has a turbocharger50configured to compress intake air. The turbocharger50has a compressor housing51, which is arranged in the middle of the intake passage11. The turbocharger50also has a turbine housing60, which is arranged in a section of the exhaust passage13that is upstream of the catalyst21. The compressor housing51and the turbine housing60are connected to each other via a bearing housing52of the turbocharger50.

The turbine housing60accommodates a turbine wheel91, which is rotated by flow of exhaust gas. The turbine wheel91is rotational about a rotation axis91aof the turbine wheel91. The turbine wheel91is connected to a first end of a shaft92. The central portion of the shaft92is accommodated in the bearing housing52. The shaft92is rotationally supported by a bearing (not shown). The rotation axis of the shaft92is coaxial with the rotation axis91aof the turbine wheel91. A second end of the shaft92is connected to a compressor wheel93. The compressor wheel93is accommodated in the compressor housing51. The rotation axis of the compressor wheel93is coaxial with the rotation axis91aof the turbine wheel91. The compressor wheel93rotates with rotation of the turbine wheel91to compress the intake air and supplies it to the cylinder12.

The turbocharger50includes a wastegate80, which is pivotally supported by the turbine housing60. The turbocharger50pivots the wastegate80to selectively close and open a bypass passage64inside the turbine housing60.

Next, the turbine housing60and the wastegate80will be described.

As shown inFIG. 2, the turbine housing60includes a housing body66, which accommodates the turbine wheel91. An accommodation space65, in which the turbine wheel91is accommodated, is defined inside the housing body66. The accommodation space65is connected to a scroll passage61, which draws exhaust gas from the outside of the turbine housing60to the accommodation space65. The scroll passage61is connected to the accommodation space65while extending spirally in the circumferential direction of the rotation axis91aof the turbine wheel91on the outer side in the radial direction of the accommodation space65.

The accommodation space65is connected to a connection passage62, which discharges exhaust gas from the accommodation space65. The connection passage62has a substantially circular cross section in a cross-sectional view orthogonal to the extending direction. The connection passage62includes an inlet portion62alocated on the upstream side and an outlet portion62clocated on the downstream side. In the connection passage62, the inner diameter of the inlet portion62aand the inner diameter of the outlet portion62care substantially the same.

A merging passage63that discharges exhaust gas to the outside of the turbine housing60is connected to the outlet portion62cof the connection passage62. The merging passage63includes a valve accommodating portion63alocated on the upstream side and an outlet portion63clocated on the downstream side. The outlet portion63cof the merging passage53has a substantially circular cross section in a cross-sectional view orthogonal to the extending direction. The inner diameter of the outlet portion63cof the merging passage63is substantially constant from the upstream end to the downstream end of the outlet portion63c.

The housing body66of the turbine housing60has the bypass passage64, which branches off the scroll passage61. The bypass passage64bypasses the accommodation space65and is connected to the valve accommodating portion63ain the merging passage63. The bypass passage64extends linearly as a whole so as to connect the upstream portion of the scroll passage61and the valve accommodating portion63ain the merging passage63. The bypass passage64has a substantially circular cross section in a cross-sectional view orthogonal to the extending direction. The bypass passage64has an outlet portion64c, which is a section including the downstream end. The inner diameter of the outlet portion64cis smaller than the inner diameter of the outlet portion62cof the connection passage62.

As shown inFIG. 2, an upstream flange67extends from the outer surface of the housing body66. The upstream flange67is located outside the upstream end of the scroll passage61. The upstream flange67connects the upstream end of the scroll passage61to the section of the exhaust passage13that is on the upstream side of the turbine housing60.

A downstream flange68extends from the outer surface of the housing body66. The downstream flange68is located radially outside the outlet portion63cof the merging passage63. The downstream flange68connects the outlet portion63cof the merging passage63to the section of the exhaust passage13on the downstream side of the turbine housing60. The catalyst21, which is arranged inside the exhaust passage13, is located on the downstream side of the turbine housing60. A region extended from the outlet portion64cof the bypass passage64along the central axis of the outlet portion64cis defined as an imaginary extension region64e. The central portion of the catalyst21is positioned in the imaginary extension region64e.

As shown inFIG. 2, the wastegate80has a substantially columnar pivot shaft83. The pivot shaft83is located in the valve accommodating portion63aof the turbine housing60and is arranged between the outlet portion62cof the connection passage62and the outlet portion64eof the bypass passage64. A first end of the pivot shaft83(the end located on the back of the sheet ofFIG. 2) is rotationally supported by the turbine housing60. The first end of the pivot shaft83is connected to an actuator (not shown). As the actuator is driven, the pivot shaft83rotates clockwise or counterclockwise about the pivot axis83aof the pivot shaft83.

A first valve member81is fixed to a second end of the pivot shaft83(the end on the near side of the sheet ofFIG. 2). The first valve member81closes the outlet portion62cof the connection passage62. The first valve member81is located on a first side (the clockwise side inFIG. 2) in the pivoting direction (the circumferential direction) of the pivot shaft83. The first valve member81is provided with a substantially disk-shaped valve portion81a. The outer diameter of the valve portion81ais larger than the inner diameter of the outlet portion62cof the connection passage62. The valve portion81aincludes a protrusion81b, which protrudes from the substantially central portion toward a second side (the counterclockwise side inFIG. 2) in the pivoting direction (the circumferential direction) in the pivot shaft83.

A second valve member82, which closes the outlet portion64cof the bypass passage64, is fixed to the protrusion81bof the first valve member81. The second valve member82is located on the second side (the counterclockwise side inFIG. 2) in the pivoting direction (the circumferential direction) of the pivot shaft83with respect to the first valve member81. The second valve member82has a disk shape as a whole. The outer diameter of the second valve member82is larger than the inner diameter of the outlet portion64cof the bypass passage64. In the present embodiment, the second valve member82is fixed to the pivot shaft83via the first valve member81. That is, the second valve member82is fixed to the pivot shaft83so as to be located separated from the first valve member81in the circumferential direction about the pivot axis83aof the pivot shaft83.

The valve portion81aof the first valve member81has a first facing surface81f, which faces the outlet portion62cof the connection passage62. The outlet portion62cof the connection passage62has a first sealing surface62f, which faces the first valve member81. When the pivot shaft83pivots in one direction as shown inFIG. 2, the first facing surface81fcontacts the first sealing surface62f. Accordingly, the first valve member81closes the outlet portion62cof the connection passage62. The second valve member82has a second facing surface82f, which faces the outlet portion64cof the bypass passage64. The outlet portion64cof the bypass passage64has a second sealing surface64f, which faces the second valve member82. When the pivot shaft83pivots in the other direction as shown inFIG. 3, the second facing surface82fcontacts the second sealing surface64f. Accordingly, the second valve member82closes the outlet portion64cof the bypass passage64.

As shown inFIG. 2, the second sealing surface64fof the bypass passage64is inclined with respect to a plane orthogonal to the central axis64dof the outlet portion64cof the bypass passage64. Specifically, the second sealing surface64fof the bypass passage64is inclined toward the side on which the outlet portion62cof the connection passage62is located with respect co the plane orthogonal to the central axis64dof the outlet portion64c.

The central axis of the inlet portion62aof the connection passage62is coaxial with the rotation axis91aof the turbine wheel91. The central axis62dof the outlet portion62cof the connection passage62is inclined with respect to the rotation axis91aof the turbine wheel91. The first sealing surface62fof the outlet portion62cof the connection passage62is oriented toward the side on which the outlet portion64cof the bypass passage64is located. That is, the central axis62dof the outlet portion62cof the connection passage62is inclined with respect to the rotation axis91aof the turbine wheel91toward the side on which the outlet portion4cof the bypass passage64is located. In the present embodiment, the central axis62dof the outlet portion62cof the connection passage62is inclined by approximately 30 degrees with respect to the rotation axis91aof the turbine wheel91. The first sealing surface62fof the outlet portion62cof the connection passage62is substantially parallel to a plane orthogonal to the central axis62dof the outlet portion62cof the connection passage62.

As shown inFIG. 3, the first facing surface81fof the first valve member81is inclined with respect to the second facing surface82fof the second valve member82to be separated away from the second facing surface82fas the distance from the pivot axis83aof the pivot shaft83increases. Specifically, the inclination angle of the first facing surface81fwith respect to the second facing surface82fis determined such that, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the first facing surface81fis inclined with respect to the central axis62dof the outlet portion62cof the connection passage62. Also, the first facing surface81ffaces the outlet portion62cof the connection passage62. In the present embodiment, the angle defined by the first facing surface81fand the central axis62dis approximately 35 degrees. Also, the inclination angle of the first facing surface81fwith respect to the second facing surface82fis determined such that, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the first facing surface81fis located on the central axis62dof the outlet portion62cof the connection passage62.

Further, the inclination angle of the first facing surface81fwith respect to the second facing surface82fis determined such that, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the first facing surface81fis inclined with respect to the central axis63dof the outlet portion63cof the merging passage63. Also, the first facing surface81ffaces the outlet portion63cof the merging passage63. Further, the inclination angle of the first facing surface81fwith respect to the second facing surface82fis determined such that, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the first facing surface81fis inclined with respect to a central axis13dof the section of the exhaust passage13on the downstream side of the turbine housing60. Also, the inclination angle of the first facing surface81fwith respect to the second facing surface82fis determined such that, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the first facing surface81fis located on the central axis13dof the section of the exhaust passage13on the downstream side of the turbine housing60. Further, the first facing surface81ffaces a section of the exhaust passage13that is on the downstream of the turbine housing60. In the present embodiment, as inclination angles that satisfy these conditions, the angle defined by the first facing surface81fand the central axis63dis set to approximately 10 degrees and the angle defined by the first facing surface81fand the central axis13dis set to approximately 40 degrees.

As shown inFIG. 2, the inclination angle of the first facing surface81fwith respect to the second facing surface82fand the distance in the circumferential direction of the pivot shaft83from the first facing surface81fto the second facing surface82fare determined such that, when the outlet portion62cof the connection passage62is closed by the first valve member81, the wastegate80is outside the imaginary extension region64e. In the present embodiment, the inclination angle of the first facing surface81fwith respect to the second facing surface82fand the distance in the circumferential direction of the pivot shaft83from the first facing surface81fto the second facing surface82fare determined by adjusting the protrusion length and protrusion direction of the protrusion81bof the first valve member81. Also, the inclination angle of the first facing surface81fwith respect to the second facing surface82fis approximately 20 degrees.

Advantages of the present embodiment will be described together with its operation.

(1) For example, in a comparative example shown inFIG. 4, the central axis of an outlet portion162cof a connection passage162is coaxial with a rotation axis91aof a turbine wheel91. A first sealing surface162fof the connection passage162is substantially parallel with a plane orthogonal to the central axis of the outlet portion162cof the connection passage162. In this case, the inclination angle between the first sealing surface162fof the connection passage162and the second sealing surface64fof the bypass passage64is approximately 100 degrees.

In contrast, in the present embodiment, the central axis62dof the outlet portion62cof the connection passage62is inclined with respect to the rotation axis91aof the turbine wheel91toward the side on which the outlet portion64cof the bypass passage64is located as shown inFIG. 2. Thus, the inclination angle between the first sealing surface62fof the connection passage62and the second sealing surface64fof the bypass passage64is smaller than that in the configuration of the comparative example described above. This reduces the pivoting range of the wastegate80, which pivots between the first sealing surface62fand the second sealing surface64f. Such reduction in the pivoting range of the wastegate80allows, for example, the stroke of the actuator that drives the wastegate80to be reduced.

(2) It is new assumed that, in the configuration of the above comparative example, the first sealing surface162fof the connection passage162is inclined with respect to a plane orthogonal to the central axis of the outlet portion162cof the connection passage162so that the first sealing surface162fis oriented toward the side on which the outlet portion64cof the bypass passage64is located. In this case, the inclination angle between the first sealing surface162fof the connection passage162and the second sealing surface64fof the bypass passage64is small. However, in this case, since the first sealing surface162fof the connection passage162is inclined as if cut obliquely, the opening area of the outlet portion162cof the connection passage162is increased. Accordingly, the first valve member81of the wastegate80is enlarged in order to close the outlet portion162cof the connection passage162. In particular, the inner diameter of the outlet portion162cof the connection passage162is larger than the inner diameter of the outlet portion64cof the bypass passage64. Therefore, the size of the first valve member81, which is already larger than the second valve member82, must be further increased. Such an increase in the size of the first valve member81of the wastegate80inevitably requires an actuator with a large driving force to pivot the wastegate80. This can result in an increased size of the whole turbocharger50.

In contrast, in the present embodiment, since the first sealing surface62fof the connection passage62and the plane orthogonal to the central axis62dof the outlet portion62cof the connection passage62are substantially parallel as shown inFIG. 2, the opening area of the outlet portion62cof the connection passage62is not excessively enlarged. This configuration prevents the first valve member81, which closes the outlet portion62cof the connection passage62, from being enlarged, thereby preventing the wastegate80from being enlarged. In addition, if the wastegate80prevented from being enlarged, the driving force of the actuator that drives the wastegate80can be made relatively small. This prevents the actuator from being enlarged.

(2) In the present embodiment, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the exhaust gas that has passed through the connection passage62flows toward the first valve member81as indicated by the arrows of broken lines inFIG. 3. The exhaust gas then applies to the wastegate80a force acting to close the outlet portion64cof the bypass passage64. Therefore, when the outlet portion64cof the bypass passage64is closed, the closed state of the bypass passage64is further reliably maintained.

(4) It is now assumed that, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the first facing surface81fof the first valve member81is parallel to the central axis62dof the outlet portion62cof the connection passage62. In this case, the exhaust gas flowing through the merging passage63flows to the downstream side while striking the inner surface of the merging passage63. Therefore, a turbulent flow tends to occur inside the merging passage63, which hampers a smooth flow of the exhaust gas.

In contrast, in the present embodiment, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the first facing surface81fof the first valve member81faces both the outlet portion62cof the connection passage62and the outlet portion63cof the merging passage63as shown inFIG. 3. The first facing surface81fof the first valve member81is inclined with respect to both the central axis62dof the outlet portion62cof the connection passage62and the central axis63dof the merging passage63. Thus, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the flow direction of the exhaust gas that has passed through the connection passage62is gradually changed by the first facing surface81fof the first valve member81, and the exhaust gas that has passed through the connection passage62is guided toward the outlet of the merging passage63as indicated by the arrows of broken lines inFIG. 3. This allows the exhaust gas that has passed through the connection passage62to flow smoothly in the merging passage63. In particular, in the present embodiment, the first facing surface81fof the first valve member81also faces the section of the exhaust passage13on the downstream side of the turbine housing60. Also, the first facing surface81fof the first valve member81is inclined with respect to the central axis13dof the section of the exhaust passage13on the downstream side of the turbine housing60. Therefore, the flow direction of the exhaust gas that has passed through the connection passage62is easily converted into the direction along the extending direction of the exhaust passage13by the first facing surface81fof the first valve member81, which contributes to smooth flow of the exhaust gas in the exhaust passage13.

(5) In the present embodiment, when the outlet portion62cof the connection passage62is closed by the first valve member81as shown inFIG. 2, the wastegate80is outside the imaginary extension region64e. Thus, as indicated by the arrows of broken lines inFIG. 2, it is possible to prevent the wastegate80from blocking the exhaust gas that has passed through the bypass passage64. As a result, the exhaust gas that has passed through the bypass passage64is easily and smoothly discharged from the inside of the turbine housing60. Further, since the catalyst21in the exhaust passage13is located within the imaginary extension region64e, the exhaust gas that has passed through the bypass passage64is easily guided toward the catalyst21. For example, the catalyst21can be warmed up early by the exhaust gas that has passed through the bypass passage64.

(6) In the present embodiment, the first facing surface81fof the first valve member81is inclined with respect to the second facing surface82fof the second valve member82to be separated away from the second facing surface82fas the distance from the pivot axis83aof the pivot shaft83increases. Therefore, as compared with a wastegate80in which the inclination angle between the first facing surface81fof the first valve member81and the second facing surface82fof the second valve member82is zero, the pivoting range of the wastegate80, which pivots between the first sealing surface62fand the second sealing surface64f, is reduced.

The above-described embodiment may be modified as follows.

In the above-described embodiment, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the first facing surface81fof the first valve member81does not necessarily need to be located on the central axis62dof the outlet portion62cof the connection passage62. For example, when a region obtained by extending the outlet portion62cof the connection passage62along the central axis62dof the outlet portion62cof the connection passage62is defined as an imaginary region, the first facing surface81fof the first valve member81may be located in the imaginary region. Even in this case, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the exhaust gas that has passed through the connection passage62applies to the wastegate80a force acting to close the outlet portion64cof the bypass passage64.

Also, for example, if the force of the wastegate80chat closes the outlet portion64cof the bypass passage64is sufficiently great when the outlet portion64cof the bypass passage64is closed by the second valve member82, the first facing surface81fof the first valve member81does not necessarily need to be located in the imaginary region.

In the above-described embodiment, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the first facing surface81fof the first valve member81does not necessarily need to be located on the central axis13dof the section of the exhaust passage13on the downstream side of the turbine housing60. For example, it is only required that the first facing surface81fof the first valve member81face both the outlet portion62cof the connection passage62and the section of the exhaust passage13on the downstream side of the turbine housing60. Also, it is only required that the first facing surface81fof the first valve member81be inclined with respect to both the central axis62dof the outlet portion62cof the connection passage62and the central axis13dof the section of the exhaust passage13on the downstream side of the turbine housing60. Accordingly, the first facing surface81fof the first valve member81guides the exhaust gas that has passed through the connection passage62from the merging passage63to the section of the exhaust passage13on the downstream side of the turbine housing60.

Further, in a case in which the first facing surface81fof the first valve member81is inclined with respect to both the central axis62dof the outlet portion62cof the connection passage62and the central axis13aof the section of the exhaust passage13on the downstream side of the turbine housing60, the first facing surface81fdoes not necessarily need to be inclined with respect to the central axis63dof the merging passage63. Even if the first facing surface81fof the first valve member81is not inclined with respect to the central axis63dof the merging passage63in this manner, the exhaust gas that has passed through the connection passage62is easily guided from the merging passage63to the section of the exhaust passage13on the downstream side of the turbine housing60by the first facing surface81fof the first valve member81.

The inclination angle of the first facing surface81fwith respect to the second facing surface82fmay be changed as needed. For example, it is only required that, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the first facing surface81fface both the outlet portion62cof the connection passage62and the outlet portion63cin the merging passage63. Then, if the first facing surface81fis inclined with respect to both the central axis62dof the outlet portion62cof the connection passage62and the central axis63dof the merging passage63, the inclination angle of the first facing surface81fwith respect to the second facing surface82fmay be changed. In addition, the inclination angle of the first facing surface81fwith respect to the second facing surface82fmay be zero. Alternatively, the first facing surface81fof the first valve member81may be inclined with respect to the second facing surface82fso as to approach the second facing surface82fof the second valve member82as the distance from the pivot axis83aof the pivot shaft83increases.

In the above-described embodiment, the inclination angle of the first facing surface81fwith respect to the second facing surface82fand the distance in the circumferential direction of the pivot shaft83from the first facing surface81fto the second facing surface82fare determined by adjusting the protrusion length and protrusion direction of the protrusion81bof the first valve member81. However, the configuration is not limited to this. For example, the inclination angle of the first facing surface81fwith respect to the second facing surface82fand the distance in the circumferential direction of the pivot shaft83from the first facing surface81fto the second facing surface82fmay be determined by the shape of the valve portion81aof the first valve member81or the shape of the second valve member82.

In the above-described embodiment, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the first facing surface81fof the first valve member81does not necessarily need to be inclined with respect to the central axis62dof the outlet portion62cof the connection passage62or the central axis63dof the merging passage63. For example, if the exhaust gas that has passed through the connection passage62can be guided to the outlet of the merging passage63by changing the shape of the merging passage, the first facing surface81fof the first valve member81does not necessarily need to be inclined with respect to the central axis62dof the outlet portion62cof the connection passage62or the central axis63dof the merging passage63. In this case, the first facing surface81fof the first valve member81does not necessarily need to face the outlet portion62cof the connection passage62or the outlet portion63cof the merging passage63.

In the above-described embodiment, when the outlet portion64cof the bypass passage64is closed by the second valve member82, the first facing surface81fof the first valve member81does not necessarily need to be inclined with respect to the central axis13dof the section of the exhaust passage13on the downstream side of the turbine housing60. For example, if the exhaust gas is allowed to flow smoothly by changing the shape of the merging passage63or the shape of the exhaust passage13, the angular relationship between the first facing surface81fof the first valve member81and the central axis13dmay be determined arbitrarily. In this case, the first facing surface81fof the first valve member81does not necessarily need to face the section of the exhaust passage13on the downstream side of the turbine housing60.

In the above-described embodiment, the wastegate80may be located within the imaginary extension region64ewhen the outlet portion62cof the connection passage62is closed by the first valve member81. For example, part of the wastegate80may be located within the imaginary extension region64eif the influence on the flow of the exhaust gas that has passed through the bypass passage64is small and the flow of the exhaust gas is not blocked.

In the above-described embodiment, the catalyst21in the exhaust passage13does not necessarily need to be located within the imaginary extension region64e. For example, the shape of the exhaust passage13allows the exhaust gas that has passed through the bypass passage64to be easily guided to the catalyst21when the outlet portion62cof the connection passage62is closed by the first valve member81, the catalyst21in the exhaust passage13does not necessarily need to be located within the imaginary extension region64e.

In the above-described embodiment, the first sealing surface62fof the connection passage62may be inclined with respect to the plane orthogonal to the central axis62dof the outlet portion62cof the connection passage62. For example, if the first sealing surface62fof the connection passage62is inclined with respect to the plane orthogonal to the central axis62dof the outlet portion62ctoward the side on which the outlet portion64cof the bypass passage64is located, the inclination angle between the first sealing surface62fof the connection passage62and the second sealing surface64fof the bypass passage64can be further reduced. This allows for a further reduction in the pivoting range of the wastegate80, which pivots between the first sealing surface62fand the second sealing surface64f.

The shape of the connection passage62in the above-described embodiment may be changed as needed. For example, both the central axis of the inlet portion62aof the connection passage62and the central axis62dof the outlet portion62cof the connection passage62may be inclined with respect to the rotation axis91aof the turbine wheel91. Further, the connection passage62may be curved in an arcuate shape. Even in this case, it is only required that the central axis62dof the outlet portion62cof the connection passage62be inclined with respect to the rotation axis91aof the turbine wheel91toward the side on which the outlet portion64cof the bypass passage64is located.

The shape of the bypass passage64in the above-described embodiment may be changed as needed. In the above-described embodiment, the bypass passage64is connected to the scroll passage61. However, the bypass passage64may be separated from the scroll passage61and be directly connected to the section of the exhaust passage13on the upstream side of the turbine housing60. That is, the bypass passage64only needs to be connected to a section in an exhaust flow passage that is located on the upstream side of the accommodation space65and extend to bypass the accommodation space65.