Turbocharger

Abstract

The present invention relates to a turbocharger. When viewed in a cross section parallel to the central axis of a shaft and including the center of gravity of a valve surface, an end portion of the valve surface on a first axial direction side is located on the first direction side in a direction orthogonal to the central axis of the shaft relative to the center of gravity. When the central axis of the shaft and the central axis of a through hole coincide with each other, when viewed in a cross section orthogonal to the central axis of the shaft and including the center of gravity, an end portion of the valve surface on a second direction side in a direction along a valve seat surface is located on the first direction side in a direction orthogonal to the valve seat surface relative to the center of gravity.

Description

Technical Field

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

[0002] The turbocharger described in Japanese Unexamined Patent Application Gazette No. 2020-084923 (JP 2020-084923 A) includes a turbine impeller, a turbine housing, an exhaust bypass valve, and a connecting rod mechanism. The turbine housing accommodates the turbine impeller. The turbine housing defines a bypass passage. The bypass passage provides a bypass between the exhaust upstream side and the exhaust downstream side relative to the turbine impeller. The turbine housing has a valve seat surface that contacts the exhaust bypass valve when the exhaust bypass valve is in a closed state. In addition, the turbine housing has a through hole extending through the wall of the turbine housing.

[0003] The wastegate valve opens and closes the bypass passage. The wastegate valve includes a shaft and a valve body. The shaft extends through the through hole and is rotatably supported by the turbine housing. The valve body extends from the end of the shaft located inside the turbine housing in the radial direction of the shaft. The valve body has a valve surface that is a flat surface that faces the valve seat surface when the wastegate valve is in a closed state. The shaft and the valve body are an integrally molded part.

[0004] The connecting rod mechanism is coupled to the end of the shaft located outside the turbine housing. The connecting rod mechanism transmits the driving force from the actuator to the wastegate valve. The wastegate valve opens and closes the bypass passage based on the driving force from the connecting rod mechanism. When the wastegate valve is in a closed state, the connecting rod mechanism applies a force directed from the valve surface to the valve seat surface to the end of the shaft located outside the turbine housing.

[0005] In addition, the valve surface is inclined relative to the central axis of the shaft. Specifically, the valve surface is inclined so as to be further separated from the central axis of the shaft as the valve surface further extends in one direction along the central axis of the shaft (the direction is the direction from the outside toward the inside of the turbine housing). Summary of the invention

[0006] In the turbocharger such as JP 2020-084923 A, since the valve surface of the valve body is inclined as described above, even when the shaft is inclined relative to the through hole by the force from the link mechanism with the wastegate valve in the closed state, it is possible to prevent a wide gap from being formed between the valve surface and the valve seat surface. However, depending on the direction of the force from the link mechanism, there is still a possibility that a gap is formed between the valve surface and the valve seat surface.

[0007] A turbocharger for solving this problem includes: a turbine impeller that rotates by the flow of exhaust gas; a turbine housing that accommodates the turbine impeller and defines a bypass passage that provides a bypass between the exhaust gas upstream side and the exhaust gas downstream side relative to the turbine impeller; a wastegate valve that opens and closes the bypass passage; and a link mechanism that transmits a driving force from an actuator to the wastegate valve. The turbine housing has a valve seat surface and a through hole, wherein the valve seat surface is a flat surface that contacts the wastegate valve when the wastegate valve is in a closed state, and the through hole extends through the wall of the turbine housing. The wastegate valve has a shaft and a valve body, wherein the shaft extends through the through hole and is rotatably supported by the turbine housing, and the valve body extends from an end of the shaft located inside the turbine housing in a radial direction of the shaft. The valve body has a valve surface which is a flat surface facing the valve seat surface when the wastegate valve is in the closed state. The shaft and the valve body are an integrally molded part. When the wastegate valve is in the closed state, the direction of the force applied by the link mechanism to the end of the shaft located outside the turbine housing is referred to as a first direction and one direction of the directions along the central axis of the shaft as a direction from the outside toward the inside of the turbine housing is referred to as a first axial direction, when viewed from the direction along the central axis of the through hole, the first direction is inclined relative to the valve seat surface; the valve seat surface is parallel to the central axis of the through hole; when viewed in a cross section parallel to the central axis of the shaft and including the center of gravity of the valve surface, the end of the valve surface on the first axial direction side is located on the first direction side in a direction orthogonal to the central axis of the shaft relative to the center of gravity; and when the central axis of the shaft and the central axis of the through hole coincide with each other and further the wastegate valve is in the closed state, when viewed in a cross section orthogonal to the central axis of the shaft and including the center of gravity of the valve surface, the end of the valve surface on the side opposite to the first direction in the direction along the valve seat surface is located on the first direction side in a direction orthogonal to the valve seat surface relative to the center of gravity.

[0008] In this turbocharger, when the wastegate valve is in a closed state, a force in a first direction acts on the end of the shaft located outside the turbine housing. Then, the central axis of the shaft is tilted relative to the central axis of the through hole, so that the end of the shaft located outside the turbine housing is displaced in the first direction, and the end of the shaft located inside the turbine housing is displaced in a direction opposite to the first direction. In the above configuration, the valve surface is not only tilted relative to the extension direction of the central axis of the shaft, but also tilted in a direction orthogonal to the central axis of the shaft. That is, the valve surface is tilted according to the inclination of the first direction relative to the valve seat surface. Therefore, even when a force in the first direction tilted relative to the valve seat surface acts on the shaft, a gap is unlikely to be formed between the valve surface and the valve seat surface.

[0009] In the above configuration, the valve surface may have a recessed annular groove, and the annular groove may extend in the valve surface so as to surround the bypass passage when the wastegate valve is in a closed state.

[0010] In this configuration, when the wastegate valve is in a closed state, a hollow portion is created between the inner surface of the annular groove and the valve seat surface. If there is a gap between the valve surface and the valve seat surface, the hollow portion exists in the flow path through which the exhaust gas leaks. Since the cross-sectional area of ​​the flow path suddenly increases at the hollow portion, the flow of the exhaust gas is disturbed and the resistance to the flow of the exhaust gas increases. Therefore, even when there is a gap between the valve surface and the valve seat surface, the amount of leaked exhaust gas can be reduced by the hollow portion defined by the annular groove.

[0011] In the above configuration, the wastegate valve may have a protrusion protruding from the valve surface, and when the wastegate valve is in a closed state, the protrusion may be inserted into the bypass passage.

[0012] In this configuration, in order to reach between the valve surface and the valve seat surface when the wastegate valve is in a closed state, the exhaust gas flows through the space between the outer peripheral surface of the protrusion and the inner peripheral surface of the bypass passage. Therefore, the cross-sectional area of ​​the flow passage through which the exhaust gas reaches between the valve surface and the valve seat surface can be reduced due to the presence of the protrusion. Compared with a configuration in which no protrusion is provided, this configuration can reduce the amount of exhaust gas reaching between the valve surface and the valve seat surface.

[0013] In the above configuration, the front end surface of the protrusion may have a recessed concave portion, and at least a portion of an inner surface of the recess may be a curved surface.

[0014] In this structure, when the wastegate valve is in a closed state, a portion of the exhaust gas that has hit the inner surface of the recess is guided by the curved surface to flow back from downstream to upstream. The exhaust gas that flows back in this way weakens the flow of the exhaust gas from upstream to downstream, thereby reducing the force of the exhaust gas trying to open the wastegate valve.

[0015] In the above configuration, the turbine housing may define a plurality of bypass passages opening in the valve seat surface. The valve body may have a recessed portion recessed from the valve surface. The recessed portion is located at the following portion of the valve body: when the wastegate valve is in a closed state, the portion of the valve body faces the portion located between the bypass passages.

[0016] In this configuration, the recessed portion exists at the portion of the valve body that faces the portion of the valve seat surface that is located between the bypass passages and is easily affected by the heat of the exhaust gas. Therefore, in this configuration, even when the valve seat surface thermally expands under the influence of the heat of the exhaust gas, it is unlikely that only the portion of the valve seat surface that is located between the bypass passages can contact the valve surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like symbols represent like elements, and in which:

[0018] Figure 1 is a schematic view of an internal combustion engine according to a first embodiment;

[0019] Figure 2 is a front view of a turbocharger according to the embodiment;

[0020] Figure 3 is a cross-sectional view showing a configuration around a turbine casing according to the embodiment;

[0021] Figure 4 is a cross-sectional view showing the configuration around the wastegate valve according to the embodiment;

[0022] Figure 5 is a front view including a partial cross-sectional view of the wastegate valve according to the embodiment;

[0023] Figure 6 is a right side view including a partial cross-sectional view of the wastegate valve according to the embodiment;

[0024] Figure 7 is a bottom view of the wastegate valve according to the embodiment;

[0025] Figure 8 is a view illustrating the configuration around a wastegate valve according to this embodiment;

[0026] Fig. 9 is a view illustrating the configuration around a wastegate valve according to this embodiment;

[0027] Fig.10 is a front view of a wastegate valve according to a second embodiment;

[0028] Fig.11 is a right side view of the wastegate valve according to the embodiment;

[0029] Fig.12 is a bottom view of the wastegate valve according to the embodiment;

[0030] Fig.13 is a view illustrating a configuration around a wastegate valve according to this embodiment; and

[0031] Fig.14 : is a view illustrating the configuration around a turbine casing according to this embodiment. DETAILED DESCRIPTION

[0032] First embodiment

[0033] The overall structure of an internal combustion engine

[0034] The following will be based on Figures 1 to 9 A first embodiment of the present invention will be described. First, the overall configuration of an internal combustion engine 10 of a vehicle to which a turbocharger 20 of the present invention is applied will be described.

[0035] like Figure 1 As 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. In the cylinder 12, fuel and intake air are mixed and burned. The exhaust passage 13 is connected to the cylinder 12. The exhaust passage 13 discharges exhaust gas from the cylinder 12. The catalyst 15 is located at a middle portion of the exhaust passage 13. The catalyst 15 removes harmful components from the exhaust gas flowing through the exhaust passage 13.

[0036] The turbocharger 20 includes a compressor housing 30 , a bearing housing 50 , a turbine housing 60 , a compressor wheel 70 , a coupling shaft 80 , and a turbine wheel 90 .

[0037] The compressor housing 30 is installed at a middle portion of the intake passage 11. The turbine housing 60 is installed at a portion of the exhaust passage 13 upstream of the catalyst 15. The bearing housing 50 is fixed to each of the compressor housing 30 and the turbine housing 60 and connects the compressor housing 30 and the turbine housing 60 to each other. Therefore, the turbocharger 20 is provided across the intake passage 11 and the exhaust passage 13.

[0038] The turbine housing 60 accommodates a turbine impeller 90. The bearing housing 50 accommodates a coupling shaft 80. The bearing housing 50 rotatably supports the coupling shaft 80 through a bearing (not shown). A first end of the coupling shaft 80 is connected to the turbine impeller 90. The compressor housing 30 accommodates a compressor impeller 70. The compressor impeller 70 is connected to a second end of the coupling shaft 80. Therefore, the compressor impeller 70 is coupled to the turbine impeller 90 through the coupling shaft 80.

[0039] When the turbine wheel 90 is rotated by the exhaust gas flowing through the inside of the turbine housing 60, the compressor wheel 70 rotates together with the turbine wheel 90 through the coupling shaft 80. As the compressor wheel 70 rotates, the intake air inside the compressor housing 30 is compressed.

[0040] Turbocharger structure

[0041] Next, the specific configuration of the turbocharger 20 will be described.

[0042] like Figure 2 As shown, the turbine housing 60 includes an arcuate portion 60A, a tubular portion 60B and a flange portion 60C. The tubular portion 60B has a generally cylindrical shape. The tubular portion 60B extends generally along the rotation axis 90A which is the rotation center of the turbine impeller 90. The arcuate portion 60A extends to surround the outer periphery of the tubular portion 60B and has a generally arcuate shape. The flange portion 60C is located at the upstream end of the arcuate portion 60A. The flange portion 60C is fixed to the exhaust passage 13 at a portion on the upstream side relative to the turbine housing 60.

[0043] like Figure 3 As shown, the turbine housing 60 defines two swirl passages 61, a receiving space 62, an exhaust passage 63, and two bypass passages 64 as spaces for exhaust gas to flow through. Figure 3 , a bypass passage 64 is shown. Each vortex passage 61 is located inside the arc portion 60A and the tubular portion 60B. The vortex passage 61 extends in an arc shape to surround the turbine impeller 90. The upstream end of the vortex passage 61 is connected to the exhaust passage 13 on the upstream side relative to the turbine housing 60. The downstream end of the vortex passage 61 is connected to the accommodating space 62. The two vortex passages 61 extend substantially parallel to each other. The accommodating space 62 is a portion of the inner space of the tubular portion 60B in which the turbine impeller 90 is located. The accommodating space 62 is connected to the exhaust passage 63. The exhaust passage 63 is a portion of the inner space of the tubular portion 60B, which portion includes the end of the tubular portion 60B on the opposite side with respect to the bearing housing 50, that is, the tubular portion 60B at Figure 3The upper end of the exhaust passage 63 is connected to the exhaust passage 13 on the downstream side relative to the turbine housing 60. Each bypass passage 64 is located inside the arc portion 60A and the tubular portion 60B. Each bypass passage 64 connects the swirl passage 61 and the exhaust passage 63 to each other. Therefore, the bypass passage 64 provides a bypass between the exhaust upstream side and the exhaust downstream side relative to the turbine impeller 90.

[0044] like Figure 4 As shown, the turbine housing 60 includes a valve seat surface 66 and a through hole 69. The valve seat surface 66 is a portion of the inner wall surface of the turbine housing 60 that defines the exhaust passage 63 and is a flat surface that surrounds the opening edge of the two bypass passages 64. Therefore, each bypass passage 64 opens in the valve seat surface 66. A portion of the inner surface of the turbine housing 60 including the valve seat surface 66 is raised compared to other portions. Fig. 9 As shown, the opening edge of each bypass passage 64 has a substantially semicircular shape. The bypass passages 64 are positioned side by side. Therefore, when viewed from a direction orthogonal to the valve seat surface 66, the shape of the opening edge of the combined two bypass passages 64 is circular as a whole.

[0045] like Figure 4 As shown, the through hole 69 extends through the wall of the turbine housing 60. The through hole 69 is located at a portion of the wall of the turbine housing 60 that defines the exhaust passage 63. The through hole 69 has a substantially perfect circular shape when viewed from a direction along a central axis 69A of the through hole 69. The central axis 69A of the through hole 69 is parallel to the valve seat surface 66.

[0046] like Figure 2 and Figure 4 As shown, the turbocharger 20 includes a wastegate valve 110, a bushing 120, a connecting rod mechanism 130, and an actuator 140. Figure 4 As shown, the bushing 120 has a generally cylindrical shape. The outer diameter of the bushing 120 is substantially equal to the inner diameter of the through hole 69. The bushing 120 is located inside the through hole 69.

[0047] like Figure 4 As shown, the wastegate valve 110 includes a shaft 111 and a valve body 112. The shaft 111 has a generally cylindrical shape. The outer diameter of the shaft 111 is slightly smaller than the inner diameter of the bushing 120. The shaft 111 passes through the bushing 120. Therefore, the shaft 111 extends through the through hole 69 of the turbine housing 60. The turbine housing 60 rotatably supports the shaft 111 through the bushing 120.

[0048] like Figure 6 As shown in FIG. 1 , the valve body 112 includes 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. Figure 4As shown, the connection portion 113 is located at the end of the shaft 111 located inside the turbine housing 60, that is, at Figure 4 At the right end of the middle axis 111. Figure 6 As shown, the valve body 114 is connected to the end of the connecting portion 113 located on the radially outer side of the shaft 111. Figure 7 As shown in FIG. 1 , the valve body 114 has a substantially circular plate shape. The surface of the valve body 114 on the opposite side to the connecting portion 113, that is, the surface of the valve body 114 on the opposite side to the connecting portion 113, Figure 7 The surface on the near side in the paper of is used as valve surface 116. Valve surface 116 is a flat surface. When the wastegate valve 110 is in a closed state, the valve surface 116 faces the valve seat surface 66. The wastegate valve 110 is an integrally molded part in which the shaft 111 and the valve body 112 are integrally molded. The wastegate valve 110 is integrally molded by casting, for example.

[0049] like Figure 2 As shown, the link mechanism 130 includes a link arm 131 and a link 132. The link arm 131 has a generally elongated plate shape. Figure 2 The right end of the middle link arm 131 is connected to the end of the shaft 111 located outside the turbine housing 60. The link arm 131 extends in the radial direction of the shaft 111. The connecting rod 132 has a generally rod-like shape. The end of the first end of the connecting rod 132 (i.e., at Figure 2 The upper end of the middle link 132 is connected to the end of the second end of the link arm 131, that is, Figure 2 The left end of the middle link arm 131. Therefore, the link 132 is coupled to a portion separated from the coupling center between the link arm 131 and the shaft 111 in the radial direction.

[0050] like Figure 2 As shown, the actuator 140 is fixed to the compressor housing 30. The actuator 140 is coupled to the second end of the connecting rod 132, that is, at Figure 2 The lower end of the middle link 132. The actuator 140 transmits the driving force to the link mechanism 130. The link mechanism 130 transmits the driving force from the actuator 140 to the wastegate valve 110 to open or close the bypass passage 64.

[0051] Specifically, when the wastegate valve 110 is changed from the open state to the closed state, the driving force of the actuator 140 causes the connecting rod 132 to move in a direction from the first end toward the second end (i.e., along Figure 2 Then, the link arm 131 converts the movement of the link 132 into a rotational movement, and the first rotational direction (i.e., the first rotational direction) in the circumferential direction of the shaft 111 is Figure 2110 rotates in the first rotation direction in the circumferential direction of the shaft 111. This causes the wastegate valve 110 to rotate in the first rotation direction in the circumferential direction of the shaft 111. Then, the valve surface 116 of the wastegate valve 110 contacts the valve seat surface 66 of the turbine housing 60. Therefore, when the wastegate valve 110 is in the closed state, the valve surface 116 of the wastegate valve 110 faces the valve seat surface 66 of the turbine housing 60, so that the downstream end of the bypass passage 64 is covered by the valve surface 116 of the wastegate valve 110. In this embodiment, the closed state is a state in which the valve surface 116 of the wastegate valve 110 contacts the valve seat surface 66 of the turbine housing 60 and the wastegate valve 110 can no longer rotate further toward the closed side.

[0052] On the other hand, when the wastegate valve 110 is changed from the closed state to the open state, the driving force of the actuator 140 causes the connecting rod 132 to move in a direction from the second end toward the first end (i.e., in the direction of Figure 2 Then, the link arm 131 converts the movement of the link 132 into a rotational movement, and the second rotational direction (i.e., the circumferential direction of the shaft 111) is rotated in the second direction. Figure 2 This causes the wastegate valve 110 to rotate in the second rotation direction in the circumferential direction of the shaft 111. Then, the valve surface 116 of the wastegate valve 110 is separated from the valve seat surface 66 of the turbine housing 60. Therefore, when the wastegate 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 wastegate valve 110.

[0053] Force applied by the linkage

[0054] Next, the force applied by the link mechanism 130 will be described.

[0055] Hereinafter, the direction of the force applied by the link mechanism 130 to the end of the shaft 111 outside the turbine housing 60 when the wastegate valve 110 is in the closed state will be referred to as a first direction L1 , and the direction opposite to the first direction L1 will be referred to as a second direction L2 .

[0056] like Figure 2 As shown, an imaginary plane including the valve seat surface 66 is defined as a valve seat imaginary plane 66Z. When the wastegate valve 110 is in the closed state, the axis 132A of the connecting rod 132 intersects the valve seat imaginary plane 66Z when viewed from the direction along the central axis 69A of the through hole 69. In this case, an example of an acute angle formed by the axis 132A of the connecting rod 132 and the valve seat imaginary plane 66Z is approximately 55°. As a result, as Figure 8As shown, when viewed from the direction along the central axis 69A of the through hole 69, the first direction L1 is inclined relative to the valve seat surface 66. The force in the first direction L1 transmitted from the connecting rod 132 is converted into a rotational motion by the connecting rod arm 131 and transmitted to the shaft 111. However, when the wastegate bypass valve 110 is in the closed state, the shaft 111 can no longer rotate further. Therefore, a force in a direction substantially the same as the direction in which the connecting rod 132 moves (i.e., in the first direction L1) acts on the shaft 111 through the connecting rod arm 131.

[0057] Valve surface structure

[0058] Next, the configuration of the valve surface 116 will be described in detail.

[0059] Hereinafter, one of the directions along the center axis 111A of the shaft 111 will be referred to as the first axis direction S1, the above-mentioned one of the directions along the center axis 111A of the shaft 111 is the direction from the outside toward the inside of the turbine casing 60, and the direction opposite to the first axis direction S1 will be referred to as the second axis direction S2.

[0060] like Figure 5 As shown, a case will be assumed in which the center axis 111A of the shaft 111 and the center axis 69A of the through hole 69 coincide with each other and the wastegate valve 110 is in a closed state. Under this assumption, the wastegate valve 110 viewed in a cross section parallel to the center axis 111A of the shaft 111 and including the center of gravity 116C of the valve surface 116 will be considered. In this case, the valve surface 116 is inclined so that the valve surface 116 is inclined in the first direction L1 (i.e., toward the center of gravity 116C) as it further extends in the first axial direction S1. Figure 5 Therefore, with respect to the center of gravity 116C, an end 116D of the valve surface 116 in the first axial direction S1 is located on one side of the first direction L1 in a direction orthogonal to the central axis 111A of the shaft 111.

[0061] exist Figure 5 In the cross section of , the actual acute angle formed by the valve surface 116 and the central axis 111A of the shaft 111 is, for example, about 0.1° to 1°. Figure 5 In FIG. 1 , the acute angle formed by the valve surface 116 and the central axis 111A of the shaft 111 is shown in an exaggerated manner. Figure 7 As shown, center of gravity 116C is the geometric center of valve surface 116 .

[0062] In addition, if Figure 6As shown, a case will be assumed in which the central axis 111A of the shaft 111 and the central axis 69A of the through hole 69 coincide with each other and the wastegate valve 110 is in a closed state. Under this assumption, the wastegate valve 110 seen in a cross section orthogonal to the central axis 111A of the shaft 111 and including the center of gravity 116C of the valve surface 116 will be considered. In this case, the valve surface 116 is inclined relative to the valve seat surface 66. Specifically, the valve surface 116 is inclined so that on the side of the second direction L2 (i.e., the valve seat surface 66 is inclined), the valve surface 116 is inclined relative to the valve seat surface 66. Figure 6 The right side in the figure) is toward the first direction L1 side in the direction orthogonal to the valve seat surface 66 (ie, toward Figure 6 Therefore, with respect to the center of gravity 116C, the end 116E of the valve surface 116 on the side of the second direction L2 in the direction along the valve seat surface 66 is located on the side of the first direction L1 in the direction orthogonal to the valve seat surface 66.

[0063] exist Figure 6 In the cross section of , the actual acute angle formed by the valve surface 116 and the valve seat surface 66 is, for example, about 0.1° to 1°. Figure 6 In FIG. 1 , the acute angle formed by the valve surface 116 and the valve seat surface 66 is shown in an exaggerated manner.

[0064] When the direction orthogonal to the valve seat surface 66 is referred to as the height direction, due to the inclination of the valve surface 116 as described above, the distance from the valve surface 116 to the center axis 111A of the shaft 111 in the height direction varies from one part to another of the valve surface 116. Specifically, a case will be assumed in which, as in the above-described example, the center axis 111A of the shaft 111 and the center axis 69A of the through hole 69 coincide with each other and the wastegate valve 110 is in a closed state. In this case, the highest point 116A in the valve surface 116 where the distance to the center axis 111A in the height direction is the longest is located farthest in the valve surface 116 on the side of the first direction L1 in the direction orthogonal to the valve seat surface 66. As Figure 7 As shown, the highest point 116A is located at the outer peripheral edge of the valve surface 116 between the end 116D of the valve surface 116 and the end 116E of the valve surface 116. The lowest point 116B in the valve surface 116 where the distance to the central axis 111A in the height direction is shortest is located farthest in the valve surface 116 on the side of the second direction L2 in the direction orthogonal to the valve seat surface 66. Figure 7 As shown, the lowest point 116B is located at the outer peripheral edge of the valve surface 116 at a position 180 degrees opposite to the highest point 116A across the center of gravity 116C.

[0065] How the Embodiment Works

[0066] As Figure 8 As indicated by the solid arrow in FIG. 1 , when the wastegate valve 110 is in the closed state, the force in the first direction L1 (ie, the force pointing to the Figure 8 The force of the lower right side in the through hole 69 acts on the end of the shaft 111 located outside the turbine housing 60. Then, the center axis 111A of the shaft 111 is tilted relative to the center axis 69A of the through hole 69, so that the end of the shaft 111 located outside the turbine housing 60 is displaced in the first direction L1, and the end of the shaft 111 located inside the turbine housing 60 is displaced in the second direction L2. As a result, the valve body 112 is tilted relative to the valve seat surface 66 according to the tilt of the shaft 111 relative to the through hole 69. Specifically, the valve body 112 is tilted so that the portion of the valve body 112 near the highest point 116A is separated from the valve seat surface 66 compared with the portion of the valve body 112 near the center of gravity 116C.

[0067] In this regard, when assuming a case in which the center axis 111A of the shaft 111 and the center axis 69A of the through hole 69 coincide with each other and the wastegate valve 110 is in a closed state, the valve surface 116 is inclined in advance.

[0068] Specifically, we will consider Figure 5 The wastegate valve 110 is shown as seen in a cross section parallel to the central axis 111A of the shaft 111 and including the center of gravity 116C of the valve surface 116. In this case, with respect to the center of gravity 116C, the end 116D of the valve surface 116 in the first axial direction S1 is located on the first direction L1 side in the direction orthogonal to the central axis 111A of the shaft 111. Therefore, the inclination of the central axis 111A of the shaft 111 relative to the central axis 69A of the through hole 69 due to the force in the first direction L1 is expected (the inclination is in the direction orthogonal to the valve seat surface 66 (i.e., Figure 8 The valve surface 116 is inclined relative to the extending direction of the central axis 111A of the shaft 111. Figure 6 The wastegate valve 110 is shown in a cross section which is orthogonal to the central axis 111A of the shaft 111 and includes the center of gravity 116C of the valve surface 116. In this case, with respect to the center of gravity 116C, the end 116E of the valve surface 116 on the side of the second direction L2 in the direction along the valve seat surface 66 is located on the side of the first direction L1 in the direction orthogonal to the valve seat surface 66. Therefore, the inclination of the central axis 111A of the shaft 111 relative to the central axis 69A of the through hole 69 due to the force in the first direction L1 is expected. Figure 8In addition to the inclination in the left-right direction in the middle of the shaft 111 (inclination in the left-right direction in the middle of the shaft 111), the valve surface 116 is also inclined in a direction orthogonal to the central axis 111A of the shaft 111. In this way, the valve surface 116 is not only inclined with respect to the extending direction of the central axis 111A of the shaft 111, but also inclined in a direction orthogonal to the central axis 111A of the shaft 111.

[0069] Effects of the Embodiments

[0070] (1-1) As described above, even when the valve body 112 is tilted due to the force in the first direction L1 tilted relative to the valve seat surface 66 so that the portion of the valve body 112 near the highest point 116A is separated from the valve seat surface 66 compared with the portion of the valve body 112 near the center of gravity 116C, the valve surface 116 tilted according to the above tilting is expected to be less likely to tilt relative to the valve seat surface 66. Since the possibility of the valve surface 116 tilting relative to the valve seat surface 66 is thereby reduced, the valve surface 116 is more likely to maintain surface contact with the valve seat surface 66 and a gap is less likely to be formed between the valve surface 116 and the valve seat surface 66 when the wastegate valve 110 is in the closed state.

[0071] Second embodiment

[0072] Structure of wastegate valve

[0073] Next, we will refer to Figure 10 to Figure 14 A second embodiment of the present invention is described. In the second embodiment, the turbocharger 20 is different in that it includes a wastegate valve 210 instead of the wastegate valve 110. In the second embodiment, the description will focus on the differences of the wastegate valve 210 from the first embodiment, and the same components as those in the first embodiment will be denoted by the same reference numerals and their description will be omitted or simplified.

[0074] like Fig.10 As shown, the valve body 114 of the wastegate valve 210 includes an annular groove 221, two protrusions 222, two recesses 223, and a recessed portion 224. The annular groove 221 is recessed from the valve surface 116. Fig.12 As shown, the annular groove 221 has a generally annular shape extending in the valve surface 116 along the outer peripheral edge of the valve surface 116. The annular groove 221 is located slightly inside the outer peripheral edge of the valve surface 116 (close to the outer peripheral edge of the valve surface 116) in the radial direction. Fig.13 As shown, an annular groove 221 extends in the valve surface 116 so as to surround the two bypass passages 64 when the wastegate valve 210 is in the closed state.

[0075] like Fig.10 As shown, the protrusion 222 protrudes from the valve surface 116. Fig.12As shown, each protrusion 222 has a substantially semicircular shape when viewed from a direction orthogonal to the valve surface 116. Each protrusion 222 is slightly smaller than the opening shape of the bypass passage 64. When the wastegate valve 210 is in the closed state, the protrusion 222 is located at the same position as the bypass passage 64. Therefore, as shown in FIG. Fig.13 As shown, when the wastegate valve 210 is in the closed state, the protrusion 222 is inserted into the bypass passage 64 .

[0076] like Fig.11 As shown, each protrusion 222 includes an inclined portion 222A and a parallel portion 222B. The inclined portion 222A is a portion of the protrusion 222 close to the central axis 111A of the shaft 111, that is, Fig.11 The front end surface of the inclined portion 222A (i.e., the portion on the left side of the inclined portion 222A) Fig.11 The lower surface of the inclined portion 222A is inclined relative to the valve surface 116. Specifically, the front end surface of the inclined portion 222A is inclined so that the protrusion amount from the valve surface 116 toward the central axis 111A of the shaft 111 becomes smaller.

[0077] The parallel portion 222B is a portion of the protrusion 222 other than the inclined portion 222A. Fig.11 The front end surface of the parallel portion 222B (i.e., the parallel portion 222B is located at the Fig.11 The lower surface in the middle) is parallel to the valve surface 116. The protrusion amount of the parallel portion 222B from the valve surface 116 is equal to the protrusion amount of the inclined portion 222A at its end portion located closer to the parallel portion 222B.

[0078] like Fig.11 As shown, the recess 223 is recessed from the front end surface of the inclined portion 222A and the front end surface of the parallel portion 222B. The end of the recess 223 located farther from the central axis 111A of the shaft 111 (i.e., the end of the recess 223 at the Fig.11 The end of the recessed portion 223 that is closer to the center axis 111A of the shaft 11 (i.e., the right end of the recessed portion 223) is located closer to the end of the parallel portion 222B that is located farther from the center axis 111A of the shaft 11. Fig.11 The left end in FIG. 2 is located at the portion of the inclined portion 222A close to the parallel portion 222B. Fig.12 As shown, when the wastegate valve 210 is viewed from a direction normal to the valve surface 116, the entire area of ​​the edge of each recess 223 is located inside the edge of the protrusion 222. Fig.13 As shown, when the valve body 112 is viewed in cross section, a region of the bottom surface of each recess 223 including the edge is a curved surface.

[0079] like Fig.10 As shown, the recessed portion 224 is recessed from the valve surface 116. Fig.12 As shown in FIG. 1 , when the wastegate valve 210 is viewed from a direction orthogonal to the valve surface 116, the recessed portion 224 is substantially located over the entire area of ​​a portion of the valve surface 116 located between the two protrusions 222. The end of the recessed portion 224 located closer to the central axis 111A of the shaft 111 (i.e., the end of the recessed portion 224 located closer to the central axis 111A of the shaft 111) is located closer to the central axis 111A of the shaft 111. Fig.12 The upper end of the recessed portion 224 (i.e., the upper end of the recessed portion 224) is located near the portion of the annular groove 221 located near the central axis 111A of the shaft 111. Fig.12 The lower end in the annular groove 221 is positioned close to a portion of the annular groove 221 that is positioned away from the central axis 111A of the shaft 111.

[0080] As described above, when the wastegate valve 210 is in the closed state, the protrusion 222 is inserted into the bypass passage 64. Fig.13 As shown, the recess 224 is located at a portion of the valve body 114 that faces a portion of the valve seat surface 66 that is located between the two bypass passages 64 when the wastegate valve 210 is in the closed state.

[0081] In this embodiment, since the valve body 114 of the wastegate valve 210 includes the annular groove 221, the two protrusions 222, the two recesses 223 and the recessed portion 224, Fig.12 As shown, the valve surface 116 has an overall annular shape.

[0082] As in the first embodiment, the valve surface 116 is a flat surface. Furthermore, as in the first embodiment, the valve surface 116 is inclined. That is, when viewed in a cross section parallel to the central axis 111A of the shaft 111 and including the center of gravity 116C of the valve surface 116, the valve surface 116 is inclined so as to be further displaced in the first direction L1 as it further extends in the first axial direction S1. Furthermore, when viewed in a cross section orthogonal to the central axis 111A of the shaft 111 and including the center of gravity 116C of the valve surface 116, the valve surface 116 is inclined so as to be further displaced toward the first direction L1 side in the direction orthogonal to the valve seat surface 66 as it further extends toward the second direction L2 side in the direction along the valve seat surface 66.

[0083] How the Embodiment Works

[0084] As Fig.13As indicated by the solid arrow in , even when the wastegate bypass valve 210 is in the closed state, a gap may be formed between the valve surface 116 and the valve seat surface 66 due to, for example, the slapping of the wastegate bypass valve 210 under the pressure of the exhaust gas. In this case, the exhaust gas leaks from the bypass passage 64 to the exhaust passage 63 through the gap between the valve surface 116 and the valve seat surface 66.

[0085] Effects of the Embodiments

[0086] In addition to the above-mentioned effect (1-1), this embodiment has the following effects (2-1) to (2-5).

[0087] (2-1) Since the wastegate valve 210 includes the annular groove 221, when the wastegate valve 210 is in a closed state, a hollow portion is created between the inner surface of the annular groove 221 and the valve seat surface 66. Therefore, if a gap is formed between the valve surface 116 and the valve seat surface 66, the hollow portion exists in the flow path through which the exhaust gas leaks. Since the cross-sectional area of ​​the flow path through which the exhaust gas leaks suddenly increases at the hollow portion, the flow of the exhaust gas is disturbed and the resistance to the flow of the exhaust gas increases. Therefore, even when a gap is formed between the valve surface 116 and the valve seat surface 66, the amount of leaked exhaust gas can be reduced by the hollow portion defined by the annular groove 221.

[0088] (2-2) In this embodiment, when the wastegate valve 210 is in the closed state, the protrusion 222 of the wastegate valve 210 is inserted into the bypass passage 64 of the turbine housing 60. Therefore, in order to reach between the valve surface 116 and the valve seat surface 66 when the wastegate valve 210 is in the closed state, the exhaust gas flows through the space between the outer peripheral surface of the protrusion 222 and the inner peripheral surface of the bypass passage 64. Therefore, the cross-sectional area of ​​the flow passage through which the exhaust gas reaches between the valve surface 116 and the valve seat surface 66 can be reduced due to the presence of the protrusion 222. As a result, the amount of exhaust gas reaching between the valve surface 116 and the valve seat surface 66 can be reduced.

[0089] (2-3) The wastegate valve 210 includes the recessed portions 223. The area including the edge of the bottom surface of each recessed portion 223 is a curved surface. Fig.13As indicated by the long and two short dashed arrows in FIG. 2 , when the exhaust gas flowing from upstream to downstream hits the central portion of the recess 223 when the wastegate valve 210 is in the closed state, the exhaust gas flows outward. Then, the exhaust gas is guided by the curved surface of the recess 223 to flow back from downstream to upstream. The exhaust gas thus flowing back weakens the flow of the exhaust gas from upstream to downstream in the bypass passage 64, so that the force of the exhaust gas trying to open the wastegate valve 210 can be reduced. As a result, a gap is less likely to be formed between the valve surface 116 and the valve seat surface 66, and even if a gap is formed, the amount of exhaust gas leaking through the gap can be reduced.

[0090] (2-4) The portion of the wall of the turbine housing 60 located between the two bypass passages 64 tends to be affected by the heat of the exhaust gas flowing through the two bypass passages 64. Therefore, the portion of the valve seat surface 66 located between the two bypass passages 64 tends to thermally expand more than, for example, the outer peripheral portion of the valve seat surface 66.

[0091] In this regard, the recessed portion 224 is present at the portion of the valve body 112 that faces the portion of the valve seat surface 66 located between the two bypass passages 64 when the wastegate valve 210 is in the closed state. Therefore, even when the valve seat surface 66 thermally expands due to the heat of the exhaust gas as described above, it is unlikely that only the portion of the valve seat surface 66 located between the two bypass passages 64 may contact the valve surface 116. As a result, it is unlikely that a gap is formed between the outer peripheral portion of the valve surface 116 and the outer peripheral portion of the valve seat surface 66.

[0092] (2-5) If Fig.14 As indicated by the solid arrow in , when the wastegate bypass valve 210 is in the open state, a portion of the exhaust gas from the bypass passage 64 hits the protrusion 222 protruding from the valve surface 116 in the wastegate bypass valve 210. When the exhaust gas hits the protrusion 222 in this way and the flow of the exhaust gas is thereby disturbed, the entire flow of the exhaust gas flowing through the exhaust passage 13 is disturbed, which hinders the smooth flow of the exhaust gas. In addition, since the flow of the exhaust gas is disturbed, the exhaust gas may not have a warming effect on the catalyst 15 as expected.

[0093] In this regard, the front end surface of the inclined portion 222A is inclined so that the amount of protrusion from the valve surface 116 becomes smaller toward the central axis 111A of the shaft 111 (i.e., toward the bypass passage 64). Therefore, the exhaust gas that has flowed through the bypass passage 64 does not hit the side surface of the protrusion 222 and flows generally along the front end surface of the inclined portion 222A. As a result, the flow of the exhaust gas that has flowed through the bypass passage 64 is less likely to be disturbed.

[0094] Modification example

[0095] The embodiment can be implemented by making the following changes thereto. The embodiment and the following modified examples can be implemented in combination to the extent that any technical inconsistency does not occur.

[0096] First Direction

[0097] - In the first and second embodiments, the first direction L1 is not limited to the examples of the embodiments. Figure 8 When describing, the first direction L1 may be the following directions: Figure 8 In the direction of the lower left, Figure 8 In the direction of the upper left or Figure 8 The first direction L1 may be any direction inclined relative to the valve seat surface 66 like these directions when viewed from the direction along the central axis 69A of the through hole 69. If the first direction L1 is inclined relative to the valve seat surface 66 in this way, the possibility of a gap being formed between the valve surface 116 and the valve seat surface 66 can be reduced by applying the technology of the present invention.

[0098] As a specific example, when the first direction is toward Figure 8 116D of the valve surface 116 in the first axial direction S1 is located on the first direction side in the direction orthogonal to the central axis 111A of the shaft 111 with respect to the center of gravity 116C. In addition, with respect to the center of gravity 116C, the end 116D of the valve surface 116 in the second direction side in the direction along the valve seat surface 66 is located on the first direction side in the direction orthogonal to the valve seat surface 66.

[0099] Annular groove

[0100] -In the second embodiment, the number of the annular grooves 221 may be changed. For example, the wastegate valve 210 may include two annular grooves 221 corresponding to the two bypass passages 64. In this configuration, when the wastegate valve 210 is in a closed state, one of the two annular grooves 221 extends in the valve surface 116 to surround one of the two bypass passages 64. Further, when the wastegate valve 210 is in a closed state, the other of the two annular grooves 221 extends in the valve surface 116 to surround the other of the two bypass passages 64. In this configuration, in order to adopt two annular grooves 221, the shape of the recessed portion 224 may be changed or the recessed portion 224 may be omitted. In addition, for example, a plurality of annular grooves 221 may be concentrically provided in the valve surface 116.

[0101] - In a second embodiment, the annular groove 221 may be omitted.

[0102] Protrusion

[0103] - In the second embodiment, it is possible to change the shape of the protrusion 222. For example, the protrusion 222 may not have the inclined portion 222A and the amount by which the entire protrusion 222 protrudes from the valve surface 116 may be constant.

[0104] - In the second embodiment, the number of protrusions 222 may be changed. For example, in some cases, when the wastegate valve 210 is in the closed state, the amount of exhaust gas leaking through one of the two bypass passages 64 is greater than the amount of exhaust gas leaking through the other of the two bypass passages 64. In this case, the wastegate valve 210 may include only one protrusion 222 inserted into one of the two bypass passages 64. In addition, for example, all protrusions 222 may be omitted.

[0105] concavity

[0106] - In the second embodiment, the number of recesses 223 may be changed. For example, the recess 223 may be provided in only one of the two protrusions 222. Furthermore, for example, a plurality of recesses 223 may be provided in one protrusion 222. Furthermore, for example, all recesses 223 may be omitted.

[0107] - The recess 223 does not necessarily have to be provided in the protrusion 222. For example, when the protrusion 222 is not used, the recess 223 recessed from the valve surface 116 may be used.

[0108] -The shape of the recess 223 may be changed. For example, the recess 223 may be recessed in a hemispherical shape. That is, the entire area of ​​the inner surface of the recess 223 may be a curved surface. In addition, for example, the inner surface of the recess 223 may not be a curved surface. Also in this configuration, the presence of the recess 223 may cause part of the exhaust gas that has hit the recess 223 to flow back from the downstream toward the upstream.

[0109] Depression

[0110] - In the second embodiment, the shape of the recessed portion 224 may be changed. For example, the recessed portion 224 may be provided only at a portion of the portion of the valve surface 116 located between the two protrusions 222. This configuration can also reduce the adverse effect of expansion of the portion of the valve seat surface 66 facing the recessed portion 224 when the wastegate valve 210 is in the closed state.

[0111] In the second embodiment, the recess 224 may be omitted. For example, if the thermal expansion of the valve seat surface 66 is relatively small, omitting the recess 224 has little effect.

[0112] Other structures

[0113] - In the first and second embodiments, the number of the bypass passages 64 may be changed. For example, the number of the bypass passages 64 may be one, or three or more. In this case, the number of the protrusions 222, the number of the recesses 223, and the number of the recessed portions 224 may be changed according to the number of the bypass passages 64. When the number of the bypass passages 64 is one, the recessed portion 224 may be omitted.

Claims

1. A turbocharger, comprising: a turbine impeller that is rotated by the flow of exhaust gas; a turbine housing housing the turbine wheel and defining a bypass passage providing a bypass between an exhaust gas upstream side and an exhaust gas downstream side relative to the turbine wheel; a wastegate valve that opens and closes the bypass passage; and a connecting rod mechanism that transmits a driving force from an actuator to the wastegate valve, The turbine housing has a valve seat surface and a through hole, wherein the valve seat surface is a flat surface that contacts the wastegate valve when the wastegate valve is in a closed state, and the through hole extends through a wall of the turbine housing, The wastegate valve has a shaft and a valve body, wherein the shaft extends through the through hole and is rotatably supported by the turbine housing, and the valve body extends in a radial direction of the shaft from an end portion of the shaft located inside the turbine housing, the valve body having a valve surface which is a flat surface facing the valve seat surface when the wastegate valve is in the closed state, The shaft and the valve body are an integrally molded part, wherein When the direction of the force applied by the link mechanism to the end of the shaft located outside the turbine housing when the wastegate valve is in the closed state is referred to as a first direction and one direction of the directions along the central axis of the shaft that is a direction from the outside toward the inside of the turbine housing is referred to as a first shaft direction, When viewed from a direction along a central axis of the through hole, the first direction is inclined relative to the valve seat surface; The valve seat surface is parallel to the central axis of the through hole; When viewed in a cross section parallel to the central axis of the shaft and including the center of gravity of the valve surface, an end of the valve surface on the first axial direction side is located on the first direction side in a direction orthogonal to the central axis of the shaft and at a first end of the valve surface relative to the center of gravity, and the valve surface is inclined relative to the central axis of the shaft; and When the center axis of the shaft and the center axis of the through hole coincide with each other and furthermore the wastegate valve is in the closed state, when viewed in a cross section orthogonal to the center axis of the shaft and including the center of gravity of the valve surface, an end of the valve surface on the side opposite to the first direction in a direction along the valve seat surface relative to the center of gravity is located on the first direction side in a direction orthogonal to the valve seat surface and at a second end of the valve surface, and the valve surface is inclined relative to the valve seat surface; The turbine housing defines a plurality of bypass passages opening into the valve seat surface; The valve body has a recessed portion recessed from the valve surface; and the recessed portion is located at a portion of the valve body that faces a portion located between the plurality of bypass passages when the wastegate valve is in the closed state; The valve surface has a recessed annular groove; and The annular groove extends in the valve surface so that when the wastegate valve is in the closed state, the annular groove is provided at a position of a portion of the valve body facing between the plurality of bypass passages, and the annular groove surrounds the plurality of bypass passages and the recessed portion without communicating with the recessed portion; and When the direction orthogonal to the valve seat surface is called the height direction, when the center axis of the shaft and the center axis of the through hole coincide with each other and the exhaust bypass valve is in a closed state, the highest point on the valve surface having the longest distance to the center axis of the shaft in the height direction is located at the peripheral edge of the valve surface between the first end of the valve surface and the second end of the valve surface, and the lowest point on the valve surface having the shortest distance to the center axis of the shaft in the height direction is located at the peripheral edge of the valve surface at a position 180 degrees relative to the highest point across the center of gravity of the valve surface.

2. The turbocharger according to claim 1, characterized in that: The wastegate valve has a protrusion protruding from the valve surface; and When the wastegate valve is in the closed state, the protrusion is inserted into the bypass passage.

3. The turbocharger according to claim 2, characterized in that: The front end surface of the protrusion has a concave recess; and At least a portion of an inner surface of the concave recess is a curved surface.

Images