Supercharging system and control method for supercharging system

Abstract

In this supercharging system, an exhaust passage forms a curve by means of an upstream part into which exhaust flows from a supercharger or a bypass passage, a curved part that changes the direction of the exhaust that has flowed into the upstream part, and a downstream part that connects the curved part and an exhaust purification catalyst. A waste gate valve has a bulging part that bulges into the bypass passage when the bypass passage is closed. The waste gate valve is configured to swing open so as to move away from the inner course of the curve, toward the downstream side, at the outlet of the bypass passage. Furthermore, the waste gate valve is configured to open within a range less than an angle at which the waste gate valve would become parallel to the central axis of the upstream part.

Description

Supercharging system and method for controlling the supercharging system

[0001] The present invention relates to a supercharging system and a control method for the supercharging system.

[0002] JP2011-179401A discloses a wastegate valve provided with a protrusion for reducing the area through which exhaust gas passes so as to smoothly control the response of an exhaust turbine.

[0003] Exhaust from internal combustion engines mounted on automobiles and the like is emitted after harmful components are reduced or removed by an exhaust purification catalyst such as a three-way catalyst. However, when the exhaust purification catalyst is in a cold state, such as immediately after starting the engine, the exhaust purification catalyst usually does not have sufficient reducing power (the ability to remove harmful gases). For this reason, the exhaust purification catalyst needs to be warmed as quickly as possible to a temperature range where it can exert sufficient reducing power.

[0004] For this reason, particularly in turbocharging systems that include an internal combustion engine and a turbocharger, a layout is usually adopted that places the turbocharger and exhaust purification catalyst as close as possible.This allows the exhaust gas to be sent to the exhaust purification catalyst while maintaining a high temperature, so the exhaust purification catalyst is warmed up quickly.

[0005] However, there are limitations to the layout in which the turbocharger and the exhaust purification catalyst can be placed close to each other. For example, if the turbocharger and the exhaust purification catalyst are placed too close to each other, the degree of freedom in the shape of the housing (particularly the turbine housing) will decrease, and other problems such as thermal fatigue of the housing will arise, which may result in a layout that cannot be adopted in reality.

[0006] An object of the present invention is to provide a supercharging system including an internal combustion engine and a supercharger, which can further accelerate the temperature rise of an exhaust purification catalyst, and a control method thereof.

[0007] One aspect of the present invention is a turbocharging system including an internal combustion engine, a turbocharger that compresses intake air of the internal combustion engine using exhaust gas from the internal combustion engine, an exhaust gas purification catalyst that purifies the exhaust gas, an exhaust passage that directs exhaust gas from the turbocharger to the exhaust gas purification catalyst, a bypass passage that directs exhaust gas to the exhaust passage without passing through the turbocharger, and a wastegate valve that opens and closes the bypass passage. In this turbocharging system, the exhaust passage is curved by an upstream section into which exhaust gas flows from the turbocharger or the bypass passage, a curved section that changes the direction of the exhaust gas that has flowed into the upstream section, and a downstream section that connects the curved section to the exhaust gas purification catalyst. The wastegate valve has a bulging section that bulges into the bypass passage when the bypass passage is closed, and is configured to swing open at the outlet of the bypass passage toward downstream, away from the inside of the curve. The wastegate valve is configured to open within an angle less than that at which the valve is parallel to the central axis of the upstream section.

[0008] According to the present invention, it is possible to provide a supercharging system that can further accelerate the temperature rise of an exhaust purification catalyst, and a control method thereof.

[0009] FIG. 1 is a block diagram showing a schematic configuration of a supercharging system. FIG. 2 is an explanatory diagram showing the layout of an exhaust system. FIG. 3 is an explanatory diagram showing the maximum opening of a wastegate valve. FIG. 4 is an explanatory diagram showing the three-dimensional positional relationship between a bypass passage and a downstream portion. FIG. 5 is an explanatory diagram showing a schematic view of the exhaust flow in a first comparative example. FIG. 6 is an explanatory diagram showing a schematic view of the exhaust flow in a second comparative example. FIG. 7 is an explanatory diagram showing a schematic view of the exhaust flow in this embodiment.

[0010] [Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0011] Fig. 1 is a block diagram showing a schematic configuration of a supercharging system 100. As shown in Fig. 1, the supercharging system 100 includes an internal combustion engine 10, a supercharger 11, and an exhaust purification catalyst 12. In this embodiment, the supercharging system 100 is mounted on a vehicle.

[0012] The internal combustion engine 10 is a driving force source for the vehicle, and converts combustion gases of gasoline or other fuel into mechanical work. The internal combustion engine 10 transmits power to the vehicle's drive shaft via a crankshaft or the like (not shown).

[0013] The supercharger 11 compresses air (hereinafter simply referred to as intake air) drawn into the internal combustion engine 10 by the flow of exhaust gas (hereinafter simply referred to as exhaust gas) from the internal combustion engine 10. The supercharger 11 is configured by an exhaust turbine supercharger (so-called turbocharger) or a mechanical supercharger. In this embodiment, the supercharger 11 is a turbocharger, and is formed integrally with the internal combustion engine 10.

[0014] Specifically, the turbocharger 11 includes a compressor 21 , a turbine 22 , and a bearing unit 23 .

[0015] The compressor 21 is provided in the intake system of the internal combustion engine 10, compresses intake air, and supplies it to the internal combustion engine 10. An impeller wheel of the compressor 21 (hereinafter referred to as the compressor wheel) is connected to an impeller wheel of the turbine 22 (hereinafter referred to as the turbine wheel) via a bearing 23. The compressor wheel is connected to the turbine wheel via the bearing 23, and rotates accordingly when the turbine wheel is rotated by the exhaust gas from the internal combustion engine 10. As a result, the compressor 21 compresses air taken in from an intake passage 24 and supplies the compressed air to the internal combustion engine 10 via an intake manifold 25. The compressor wheel and turbine wheel are not shown in the figure.

[0016] The turbine 22 is provided in the exhaust system of the internal combustion engine 10, and rotates a turbine wheel by the flow of exhaust gas introduced via an exhaust manifold 26. After rotating the turbine wheel, the exhaust gas from the internal combustion engine 10 is discharged into an exhaust passage 28 via a turbocharger outlet passage 27. The exhaust passage 28 is a passage that guides the exhaust gas from the turbocharger 11 to the exhaust purification catalyst 12.

[0017] The bearing portion 23 is a bearing that supports a shaft (not shown) that connects the turbine wheel and the compressor wheel.

[0018] In this embodiment, the turbocharger 11 includes a bypass passage 31 and a wastegate valve 32 in addition to the basic configuration described above.

[0019] The bypass passage 31 is a passage that guides the exhaust gas from the internal combustion engine 10 to the exhaust passage 28 without passing through the turbocharger 11. The bypass passage 31 branches off from the exhaust manifold 26 and connects the exhaust manifold 26 and the exhaust passage 28.

[0020] The wastegate valve 32 is a valve that opens and closes the bypass passage 31. In this embodiment, the wastegate valve 32 is provided at the outlet of the bypass passage 31, i.e., at the connection end of the bypass passage 31 with respect to the exhaust passage 28 (the junction with the exhaust passage 28). The specific mounting angle of the wastegate valve 32 with respect to the bypass passage 31 is arbitrary. In this embodiment, the wastegate valve 32 is provided so as to be approximately perpendicular to the bypass passage 31 when the bypass passage 31 is closed.

[0021] When the wastegate valve 32 is closed, the exhaust gas from the internal combustion engine 10 flows into the exhaust passage 28 via the turbine 22. When the wastegate valve 32 is fully open, the exhaust gas from the internal combustion engine 10 essentially flows into the exhaust passage 28 via the bypass passage 31. When the wastegate valve 32 is opened to an opening degree less than the maximum opening degree, the exhaust gas according to the opening degree of the wastegate valve 32 is released into the exhaust passage 28 without passing through the turbine 22. This adjusts the amount of exhaust gas flowing into the turbine 22. As a result, the compression pressure of the intake air by the compressor 21 (boost pressure) is adjusted. The boost pressure is adjusted not only when it is necessary to prevent damage to the internal combustion engine 10 or the supercharger 11, but also when the output torque of the internal combustion engine 10 is adjusted.

[0022] In this embodiment, the opening / closing and opening degree (opening angle) of the wastegate valve 32 are electronically controlled by a controller 33. The controller 33 is configured, for example, with one or more computers, and is programmed to open / close the wastegate valve 32 or adjust the opening degree of the wastegate valve 32 according to the torque to be output by the internal combustion engine 10, the boost pressure, the temperature of the exhaust purification catalyst 12, and the like. In particular, in this embodiment, the controller 33 controls the wastegate valve 32 to be fully open when it is necessary to warm up the exhaust purification catalyst 12, such as when starting the internal combustion engine 10. As a result, when the exhaust purification catalyst 12 is too cold to exert sufficient reducing power, a large amount of exhaust gas at a higher temperature than that passing through the turbine 22 is sent to the exhaust purification catalyst 12, so that the exhaust purification catalyst 12 is warmed up quickly.

[0023] In this embodiment, the maximum opening degree of the wastegate valve 32 (the opening degree when fully open) is determined in advance by a mechanical mechanism. However, the maximum opening degree of the wastegate valve 32 can be determined by control by the controller 33. In other words, the maximum opening degree that can be achieved during control (the controlled maximum opening degree) can be determined within the range of the maximum opening degree determined by the mechanical mechanism (the mechanical maximum opening degree).

[0024] The exhaust purification catalyst 12 is provided in the exhaust passage 28 and purifies (reduces) harmful gases contained in the exhaust gas into harmless gases. The exhaust purification catalyst 12 reduces, for example, carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NO ｘ Therefore, when the exhaust purification catalyst 12 is at a low temperature, the exhaust purification catalyst 12 may not exhibit sufficient reducing power. For this reason, when the exhaust purification catalyst 12 is at a low temperature, it is necessary to warm up the exhaust purification catalyst 12 as soon as possible.

[0025] 2 is an explanatory diagram showing the layout of the exhaust system. As shown in FIG. 2, the exhaust passage 28 includes an upstream portion 41, a curved portion 42, and a downstream portion 43.

[0026] The upstream section 41 is an upstream portion along the flow of exhaust gas in the exhaust passage 28, and is a portion of the exhaust passage 28 into which exhaust gas flows from the turbocharger 11 (turbine 22) or the bypass passage 31. The exhaust gas that flows into the upstream section 41 flows into the curved section 42.

[0027] The curved portion 42 is a midstream portion along the flow of exhaust gas in the exhaust passage 28, and is a portion of the exhaust passage 28 that changes the direction of exhaust gas that has flowed into the upstream portion 41. The curved portion 42 has a central axis that is aligned with the central axis L of the upstream portion 41 at the connection end with the upstream portion 41. １ Similarly, the central axis of the curved portion 42 at the connecting end with the downstream portion 43 coincides with the central axis L of the downstream portion 43. ２ Specifically, the curved portion 42 bends the direction of the exhaust gas that has flowed into the upstream portion 41 by, for example, about 60 degrees to about 120 degrees. In this embodiment, the curved portion 42 changes the flow of the exhaust gas by approximately 90 degrees. That is, the central axis L of the upstream portion 41 １ and the central axis L of the downstream portion 43 ２ The angle α formed by the arrows is approximately 90 degrees.

[0028] The downstream portion 43 is a downstream portion along the flow of exhaust gas in the exhaust passage 28, and is a portion of the exhaust passage 28 that connects the curved portion 42 and the exhaust purification catalyst 12. Therefore, the exhaust gas that flows from the curved portion 42 into the downstream portion 43 flows into the exhaust purification catalyst 12.

[0029] The exhaust passage 28 forms a curve as a whole due to these sections (especially the curved section 42). The upstream section 41 and the downstream section 43 are both generally cylindrical. The cross section of the curved section 42 perpendicular to the center line (not shown) is generally circular. In other words, the curved section 42 is a bent cylinder.

[0030] In principle, the exhaust gas can pass anywhere in the entire curved exhaust passage 28. In the following, the exhaust gas passage 28 will be described with reference to the central axis L of the upstream portion 41. １ and the central axis L of the downstream portion 43 ２In a plane including the curve, the passageway on the inside of the curve formed by the exhaust passage 28 is referred to as the inner course, and the passageway on the outside is referred to as the outer course. Furthermore, the inner wall surface along the inner course of the exhaust passage 28 is referred to as the inner course wall, and the inner wall surface along the outer course of the exhaust passage 28 is referred to as the outer course wall. The inner course wall is formed by an inner course wall 50a of the upstream portion 41, an inner course wall 50b of the curved portion 42, and an inner course wall 50c of the downstream portion 43. Similarly, the inner wall surface along the outer course of the exhaust passage 28 is referred to as the outer course wall. The outer course wall is formed by an outer course wall 51a of the upstream portion 41, an outer course wall 51b of the curved portion 42, and an outer course wall 51c of the downstream portion 43.

[0031] The central axis L of the upstream portion 41 １ The downstream direction of the exhaust gas along the central axis L of the upstream portion 41 is defined as the Y direction. １ and the central axis L of the downstream portion 43 ２ In the plane including the curved portion 42, the direction perpendicular to the Y direction and in which the downstream portion 43 is located is defined as the X direction. In this embodiment, the curved portion 42 is bent at a substantially right angle, so that the central axis L of the downstream portion 43 connected thereto is ２ is parallel to the X direction. The Z direction is perpendicular to the X and Y directions.

[0032] The bypass passage 31 is formed in a generally cylindrical shape. The bypass passage 31 is connected obliquely to the upstream portion 41. That is, the central axis L of the bypass passage 31 is ３ and the central axis L of the upstream portion 41 １ In this embodiment, the central axis L of the bypass passage 31 is not parallel to the axis L of the bypass passage 31. ３ is the central axis L of the upstream portion 41 １ The bypass passage 31 is inclined at a predetermined angle (hereinafter referred to as a connection angle β) with respect to the upstream portion 41. Specifically, the connection angle β of the bypass passage 31 with respect to the upstream portion 41 is, for example, about 30 degrees to about 60 degrees.

[0033] The wastegate valve 32 is a so-called swing valve and is provided at the outlet of the bypass passage 31. That is, the wastegate valve 32 is configured to swing open at the outlet of the bypass passage 31 toward the downstream of the exhaust (exhaust flowing through the bypass passage 31) so as to move away from the inside of the curve formed by the exhaust passage 28. In FIG. 2 , a solid line indicates a state in which the wastegate valve 32 closes the bypass passage 31 (hereinafter referred to as a closed state), and a dashed line indicates a state in which the wastegate valve 32 opens the bypass passage 31 (hereinafter referred to as an open state). In addition, the position of the wastegate valve 32 in the closed state may be referred to as a closed position, and the position of the wastegate valve 32 in the open state may be referred to as an open position. In particular, a state in which the wastegate valve 32 is open to the maximum opening degree may be referred to as a fully open state, and the position of the wastegate valve 32 in the fully open state may be referred to as a fully open position. In FIG. 2, the mechanism (such as a hinge or actuator) for controlling the opening degree of the wastegate valve 32 is omitted.

[0034] The wastegate valve 32 of this embodiment is not simply a flat plate (disk), but has a seat portion 61 and a bulge portion 62 .

[0035] The seating portion 61 is a portion that seals the outlet of the bypass passage 31 when the wastegate valve 32 is closed. The seating portion 61 has, for example, a disk shape. In this embodiment, the end of the seating portion 61 abuts against the outer edge of the outlet of the bypass passage 31, thereby sealing the bypass passage 31. Therefore, the seating portion 61 essentially functions as a sealing valve for the bypass passage 31.

[0036] The bulging portion 62 is a portion (convex portion) that bulges from the seating portion 61. In the closed state, the bulging portion 62 bulges into the bypass passage 31. That is, the bulging portion 62 is provided on the bypass passage 31 side of the seating portion 61.

[0037] The bulge portion 62 is configured to adjust the amount of exhaust gas that escapes from the bypass passage 31 to the exhaust passage 28 (upstream portion 41) in accordance with the opening degree of the wastegate valve 32 until the wastegate valve 32 is fully open. Specifically, when the wastegate valve 32 is opened, a portion of the bulge portion 62 remains in the bypass passage 31 in accordance with the opening degree, and adjusts (reduces) the flow path cross-sectional area at the outlet of the bypass passage 31. As a result, the flow rate of exhaust gas that escapes from the bypass passage 31 to the exhaust passage 28 (upstream portion 41) is adjusted more smoothly in accordance with the opening degree of the wastegate valve 32 than in a case where the bulge portion 62 is not present.

[0038] Furthermore, the bulging portion 62 adjusts the flow of exhaust gas within the exhaust passage 28 (hereinafter referred to as exhaust flow) that escapes from the bypass passage 31 to the exhaust passage 28 (upstream portion 41). That is, the bulging portion 62 regulates the exhaust flow within the exhaust passage 28. In this embodiment, when the wastegate valve 32 is fully opened to warm the exhaust purification catalyst 12, the bulging portion 62 causes the exhaust gas flowing in from the bypass passage 31 to generally concentrate on the inner course of the exhaust passage 28.

[0039] The shape of the bulging portion 62 can be determined arbitrarily so as to achieve the above-described functions. Specifically, the bulging portion 62 may be formed in a spherical shape or a conical shape (a conical shape). In the present embodiment, the bulging portion 62 is formed in a generally spherical shape. The amount of bulging (protrusion length) of the bulging portion 62 relative to the seating portion 61 is determined so that the entire bulging portion 62 protrudes outside the bypass passage 31 when the wastegate valve 32 is fully opened. In particular, in the present embodiment, the shape and amount of bulging of the bulging portion 62 are determined so that the bulging portion 62 contacts the cross section at the outlet of the bypass passage 31 when the wastegate valve 32 is fully opened. This is to ensure the maximum exhaust flow rate without narrowing the flow path cross-sectional area of ​​the bypass passage 31 when the wastegate valve 32 is fully opened.

[0040] The exhaust purification catalyst 12 includes a diffuser 66 and a catalyst body 67. Exhaust gas flowing into the exhaust purification catalyst 12 from the downstream portion 43 is diffused by the diffuser 66, purified by the catalyst body 67, and then discharged outside the vehicle.

[0041] The opening angle of the wastegate valve 32 when fully open, that is, the maximum opening degree of the wastegate valve 32, will be described below.

[0042] 3 is an explanatory diagram showing the maximum opening degree of the wastegate valve 32. In this example, the central axis L of the upstream portion 41 is １ and the central axis L of the downstream portion 43 ２ In a plane including the above, a line extending from the surface of the seating portion 61 (for example, the surface on which the bulge portion 62 is formed) is referred to as an extension line of the wastegate valve 32. In FIG. 3, the extension line C of the wastegate valve 32 when it is in the closed state is １ and an extension line C of the wastegate valve 32 when it is in a fully open state. ２ and are shown by dashed lines.

[0043] As shown in FIG. 3, the wastegate valve 32 is １ That is, the extension line C of the upstream portion 41 with respect to the central axis L1 of the upstream portion 41 is ２ The fully open position of the wastegate valve 32 is determined so that the angle γ is greater than zero (γ>0). It is particularly preferable that the maximum opening angle of the wastegate valve 32 be set so that the angle γ is greater than or equal to about 15 degrees and less than or equal to about 60 degrees. This makes it easier for the bulge portion 62 to concentrate (drift) the exhaust flow in the exhaust passage 28 near the inside course.

[0044] As described above, in this embodiment, the connection angle β of the bypass passage 31 with respect to the upstream section 41 is in the range of approximately 30 degrees to approximately 60 degrees. Therefore, when the connection angle β is approximately 30 degrees, the maximum opening angle of the wastegate valve 32 is set, for example, so that the angle γ is approximately 60 degrees. Also, when the connection angle β is approximately 60 degrees, the maximum opening angle of the wastegate valve 32 is set, for example, so that the angle γ is approximately 30 degrees.

[0045] In FIG. 3, an extension line L of the inside wall 50a of the upstream portion 41 ４ The extension line L of this inside wall 50a is ４ In this relationship, the wastegate valve 32 is located along the extension line C of the wastegate valve 32.２ But the first point P １ and the second point P ２ Line segment P connecting １ -P ２ It is more preferable that the wastegate valve 32 is configured to open within a range where the extension line C intersects with the line C. ２ is the second point P ２ The first point P １ is an extension line C of the wastegate valve 32 when it is in a closed state. １ and the extension line L of the inside wall 50a ４ In this embodiment, the first point P １ is essentially the connection point between the upstream portion 41 and the bypass passage 31. ２ is the extension line L of the inside wall 50a ４ and the outer course wall 51 b of the curved portion 42 .

[0046] In this case, the wastegate valve 32 is ２ The wastegate valve 32 may be configured to open in a range where the extension line C of the wastegate valve 32 intersects with the inner wall 50 a of the upstream portion 41 or the inner wall 50 b of the curved portion 42. ２ In this case, the bulging portion 62 is likely to generate a particularly strong exhaust flow on the inner course of the exhaust passage 28.

[0047] The wastegate valve 32 is connected to the extension line C ２ The wastegate valve 32 can be configured to open to a range in which the extension line C ２ In this way, in the fully open state, the extension line C of the wastegate valve 32 may be in a range where it does not intersect with the inside wall 50a or the inside wall 50b. ２ When the exhaust gas passes between the inner wall 50 b and the outer wall 51 b of the curved portion 42 , the bulging portion 62 can generate a smooth and strong exhaust flow on the inner side of the exhaust passage 28 .

[0048] Furthermore, in FIG. 3, an extension line C of the wastegate valve 32 in the fully open state ２ The point of contact between the inner wall 50b of the curved portion 42 and the inner wall 50b of the curved portion 42 is designated as a third point P ３ As shown in FIG. 3, the wastegate valve 32 in the fully open state is shown as an extension line C ２ It is particularly preferable that the maximum opening degree is set so that the extension line C of the wastegate valve 32 contacts the inside wall 50b of the curved portion 42. ２ However, it is particularly preferable that the wastegate valve 32 is configured to open until it contacts a corner portion of the inside course of the exhaust passage 28. In this way, when the wastegate valve 32 is fully open and opens so as to contact a corner portion of the inside course of the exhaust passage 28, the bulging portion 62 optimizes the exhaust flow that concentrates (drifts) near the inside course, and the exhaust gas that escapes from the bypass passage 31 tends to warm up the exhaust purification catalyst 12 particularly quickly. In this embodiment, as shown in FIG. 3, the wastegate valve 32 is configured to open until it contacts a corner portion of the inside course of the exhaust passage 28. ２ The maximum opening angle is set so that the inner wall 50b of the curved portion 42 comes into contact with the inner wall 50b.

[0049] In addition, the maximum opening degree of the wastegate valve 32 is the extension line C of the wastegate valve 32. ２ and the extension line L of the inside wall 50b ４ The angle δ at which the arrows intersect is preferably set to be equal to or greater than about 15 degrees and equal to or less than about 60 degrees. This makes it easier for the bulging portion 62 to concentrate (drift) the exhaust flow in the exhaust passage 28 near the inside course.

[0050] In this embodiment, since the upstream portion 41 is formed in a cylindrical shape, the central axis L of the upstream portion 41 １ and the extension line L of the inside wall 50a ４ are parallel. Therefore, the angle γ and the angle δ are substantially equal. Therefore, the numerical condition that the angle γ must satisfy (15≦γ≦60) and the numerical condition that the angle δ must satisfy (15≦δ≦60) have substantially the same technical meaning.

[0051] However, when the upstream portion 41 is configured by a pipe whose cross-sectional area expands or contracts along the flow of the exhaust gas, for example, the central axis L of the upstream portion 41 １ and the extension line L of the inside wall 50a ４ In this case, the numerical conditions that the angle γ must satisfy and the numerical conditions that the angle δ must satisfy have different technical significance. １ and the extension line L of the inside wall 50a ４ are non-parallel, it is preferable that at least one of the numerical conditions that the angle γ should satisfy and the numerical conditions that the angle δ should satisfy is satisfied, and it is particularly preferable that both of these conditions be satisfied.

[0052] 4 is an explanatory diagram showing the three-dimensional positional relationship between the bypass passage 31 and the downstream portion 43. As shown in FIG. １ When viewed in the Y direction, the central axis L of the upstream portion 41 １ and the central axis L of the downstream portion 43 ２ and are on the same plane (XY plane). ３ The central axis L of the upstream portion 41 is also on this plane. １ In contrast, the bypass passage 31 and the downstream portion 43 are on the same side (the positive side in the X direction). Therefore, the exhaust system in the supercharging system of this embodiment has a layout in which the flow of exhaust gas that escapes from the bypass passage 31 to the exhaust passage 28 is turned around. In this way, a layout in which the flow of exhaust gas is turned around is one of the layouts in which it takes a long time for the temperature of the exhaust purification catalyst 12 to rise when it is heated.

[0053] In this embodiment, the central axis L of the bypass passage 31 ３ is the central axis L of the upstream portion 41 １ and the central axis L of the downstream portion 43 ３ However, the central axis L of the upstream portion 41 is on a plane formed by the central axis L of the upstream portion 41. １ On the other hand, if the bypass passage 31 and the downstream portion 43 are on the same side and the layout is such that the flow of exhaust gas escaping from the bypass passage 31 to the exhaust passage 28 is substantially turned around, the central axis L of the bypass passage 31 ３does not necessarily lie on this plane.

[0054] As described above, the wastegate valve 32 is provided at the outlet of the bypass passage 31 and is aligned with the central axis L of the upstream portion 41. １ Therefore, the wastegate valve 32 is configured to open within a range of an angle less than the angle at which the wastegate valve 32 is parallel to the central axis L of the upstream portion 41. １ When viewed in the direction of the arrow, it is within the range of the upstream portion 41.

[0055] That is, when viewed in the XZ plane, the wastegate valve 32 in an open state (particularly in a fully open state) is within the range of the upstream portion 41. In this way, since the wastegate valve 32 in an open state is within the range of the upstream portion 41, the exhaust flow generated by the bulging portion 62 is not disturbed and is likely to concentrate on the inside course. For example, when the wastegate valve 32 is provided in the bypass passage 31, and the wastegate valve 32 in an open state deviates from the range of the upstream portion 41, the exhaust flow generated by the bulging portion 62 is likely to concentrate on the inside course at the connection portion between the bypass passage 31 and the upstream portion 41 (first point P １ However, when the wastegate valve 32 in the open state is within the range of the upstream section 41 as described above, the exhaust flow generated by the bulging section 62 is less likely to be disturbed by the connection between the bypass passage 31 and the upstream section 41, etc., and tends to concentrate on the inside course while maintaining a strong flow.

[0056] Furthermore, when viewed in the XZ plane, the wastegate valve 32 in the closed state is located within the range of the upstream portion 41. In this way, by having the wastegate valve 32 in the closed state located within the range of the upstream portion 41, the distance between the exhaust flow generated by the bulge portion 62 and the inside course wall 50a is kept small. As a result, the exhaust flow generated by the bulge portion 62 is likely to form a strong flow along the inside course. When the wastegate valve 32 in the open state (fully open state) and the closed state is located in the upstream portion 41, the exhaust flow generated by the bulge portion 62 is particularly likely to form a strong flow along the inside course.

[0057] In addition, in terms of the relationship between the supercharger outlet passage 27 and the bypass passage 31, the supercharger outlet passage 27 is provided on the outer course side of the exhaust passage 28, and the bypass passage 31 is provided on the inner course side of the exhaust passage 28. Therefore, the turning angle of the exhaust gas introduced from the supercharger outlet passage 27 is smaller than the turning angle of the exhaust gas introduced from the bypass passage 31. In this embodiment, the central axis L of the upstream portion 41 is １ When viewed in the direction of the arrow L, the bypass passage 31 is １ The exhaust passage 28 is connected to (converges with) the exhaust passage 28 at a position that is more eccentric toward the inside than the exhaust passage 28 .

[0058] In this layout, in a normal situation where exhaust gas is introduced into the exhaust passage 28 mainly from the turbocharger outlet passage 27, the exhaust gas is smoothly guided to the exhaust purification catalyst 12. On the other hand, in a situation where exhaust gas is introduced into the exhaust passage 28 mainly from the bypass passage 31 in order to warm up the exhaust purification catalyst 12, the heat of the exhaust gas is likely to dissipate before it reaches the exhaust purification catalyst 12. In other words, the exhaust system in the turbocharging system of this embodiment has a layout that is optimized as a whole for normal situations. For this reason, in the turbocharging system of this embodiment, in a situation where the exhaust purification catalyst 12 is to be warmed up, the shape (bulge portion 62) and opening degree of the wastegate valve 32 are devised as described above. As a result, when the exhaust purification catalyst 12 needs to be warmed up, the exhaust purification catalyst 12 can be warmed up earlier than in a case where such devise is not made.

[0059] Below, we will explain the action of the supercharging system 100 configured as above, particularly the action in the scene of warming up the exhaust purification catalyst 12. Here, we will explain the estimated mechanism by which the supercharging system 100 produces its action, but even if part or all of this estimated mechanism lacks accuracy, the supercharging system 100 of this embodiment will still produce the action described below.

[0060] 5 is an explanatory diagram showing a schematic diagram of the flow of exhaust gas in the first comparative example. The layout of the exhaust system in the turbocharging system of the first comparative example is the same as the layout of the exhaust system in the turbocharging system 100 of the embodiment. However, in the turbocharging system of the first comparative example, the wastegate valve 51 is configured as a simple flat plate (disc), and when the exhaust purification catalyst 12 is heated, the wastegate valve 51 is aligned with the central axis L of the upstream portion 41. １ 5, the wastegate valve 51 is configured to open at an angle greater than the central axis L of the bypass passage 31. ３ 5, the arrows shown inside the bypass passage 31 and the exhaust passage 28 indicate the exhaust flow when the exhaust purification catalyst 12 is warmed.

[0061] As in the first comparative example shown in Fig. 5, if the wastegate valve 51 is configured as a simple flat plate and is opened substantially without restriction when warming up the exhaust purification catalyst 12, the exhaust flow escaping from the bypass passage 31 to the exhaust passage 28 will flow into the upstream portion 41 and will diffuse widely towards the outer wall 51b of the curved portion 42. Also, when the exhaust purification catalyst 12 needs to be warmed up, the outer wall 51b of the curved portion 42 will naturally also be in a cooled state. For this reason, even if the exhaust flow is at a high temperature immediately after being introduced into the exhaust passage 28, it will diffuse over a wide range W before being led to the exhaust purification catalyst 12. １ Therefore, in the first comparative example, at least the range W １ Until this portion is warmed up, the temperature rise of the exhaust purification catalyst 12 stagnates. In other words, it takes a long time to warm up the exhaust purification catalyst 12 until it can exert a sufficient reducing power.

[0062] 6 is an explanatory diagram that shows a schematic diagram of the flow of exhaust gas in the second comparative example. The layout of the exhaust system in the supercharging system of the second comparative example is the same as the layout of the exhaust system in the supercharging system 100 of the embodiment. However, in the supercharging system of the second comparative example, the wastegate valve 51 is configured as a simple flat plate (disc). Note that in the supercharging system of the second comparative example, similar to the supercharging system 100 of the embodiment, when warming up the exhaust purification catalyst 12, the wastegate valve 51 is aligned with the central axis L of the upstream portion 41. １ 6, the wastegate valve 51 is configured to open within a range less than an angle at which it is parallel to the inside wall 50b of the curved portion 42. Here, similar to the wastegate valve 32 of the embodiment, the wastegate valve 51 is configured to open until its extension line contacts the inside wall 50b of the curved portion 42. That is, the second comparative example is an example in which the maximum opening degree of the wastegate valve 51 is set (limited) similarly to the wastegate valve 32 of the embodiment, compared to the first comparative example. Note that in FIG. 6, arrows shown inside the bypass passage 31 and the exhaust passage 28 indicate the exhaust flow when the exhaust purification catalyst 12 is warmed. Also in FIG. 6, the exhaust flow in the first comparative example is indicated by a dotted line.

[0063] As shown in FIG. 6, in the second comparative example, the wastegate valve 51 is configured as a simple flat plate, and when the exhaust purification catalyst 12 is heated, the wastegate valve 51 is moved in a direction parallel to the central axis L of the upstream portion 41. １ When the outer wall 51b is opened within a range of less than an angle parallel to the outer wall 51b, the diffusion of the exhaust flow is somewhat suppressed compared to the first comparative example. ２ Therefore, it still takes a long time to warm up the exhaust purification catalyst 12 to a temperature at which it can exert sufficient reducing power.

[0064] 7 is an explanatory diagram showing a schematic diagram of the flow of exhaust gas in this embodiment. In this embodiment, as described above, when the exhaust purification catalyst 12 is warmed, the wastegate valve 32 is aligned with the center axis L of the upstream portion 41. １ The wastegate valve 32 is configured to open within a range of an angle less than that at which the central axis L of the upstream portion 41 is parallel to the central axis L of the upstream portion 41.１ The wastegate valve 32, which is opened within a range of less than an angle parallel to the exhaust pipe 31, generally acts to deflect the exhaust flow toward the incourse (incourse wall 50a). Furthermore, the bulge portion 62 generally acts to suppress turbulence in the exhaust flow that hits the wastegate valve 32 and smoothly divert the exhaust flow while maintaining a strong flow. Therefore, in this embodiment, the combined effect of the opening limit and shape (shape of the bulge portion 62) of the wastegate valve 32 produces a stronger and more concentrated exhaust flow along the incourse (incourse wall 50a) than in the second comparative example, as shown in FIG. 7 .

[0065] As a result, in this embodiment, the exhaust flow is limited to a range W where the exhaust flow strikes the outer wall 51b of the curved portion 42. ３ is that of the second comparative example (range W ２ ) is even narrower than in the first and second comparative examples. For this reason, in this embodiment, the exhaust flow receives less heat from the outer course wall 51b of the curved portion 42, and flows into the exhaust purification catalyst 12 carrying more heat than in the first and second comparative examples. Therefore, in this embodiment, the time required to warm up the exhaust purification catalyst 12 is short. Also, when comparing after a certain time has elapsed since the start of warming up the exhaust purification catalyst 12, the temperature of the exhaust purification catalyst 12 is higher in this embodiment than in the first and second comparative examples.

[0066] [Modification] In the above embodiment, the maximum opening degree of the wastegate valve 32, i.e., the opening degree of the wastegate valve 32 when warming the exhaust purification catalyst 12, is determined in advance by a mechanical mechanism, but this is not limiting. For example, the opening degree of the wastegate valve 32 when warming the exhaust purification catalyst 12 can be limited by control by the controller 33. Therefore, in the supercharging system 100 of the above embodiment, mechanically, the wastegate valve 32 is aligned with the central axis L of the upstream portion 41. １ When the exhaust purification catalyst 12 is heated, the wastegate valve 32 is opened at an angle greater than the central axis L of the upstream portion 41 by the control of the controller 33. １ In this case, the same effects as those of the above embodiment can be achieved.

[0067] As described above, the turbocharging system according to this embodiment and the modified example is a turbocharging system 100 having the internal combustion engine 10, the turbocharger 11 that compresses the intake air of the internal combustion engine 10 using exhaust gas from the internal combustion engine 10, the exhaust purification catalyst 12 that purifies the exhaust gas, the exhaust passage 28 that guides the exhaust gas from the turbocharger 11 to the exhaust purification catalyst 12, the bypass passage 31 that guides the exhaust gas to the exhaust passage 28 without passing through the turbocharger 11, and the wastegate valve 32 that opens and closes the bypass passage 31. In this turbocharging system 100, the exhaust passage 28 forms a curve by including an upstream section 41 into which exhaust gas flows from the turbocharger 11 or the bypass passage 31, a curved section 42 that changes the direction of the exhaust gas that has flowed into the upstream section 41, and a downstream section 43 that connects the curved section 42 to the exhaust purification catalyst 12. The wastegate valve 32 has a bulge section 62 that bulges into the bypass passage 31 when the bypass passage 31 is closed. The wastegate valve 32 is configured to swing open at the outlet of the bypass passage 31 toward the downstream and away from the inside of the curve. The wastegate valve 32 is aligned with the central axis L of the upstream portion 41. １ The angle γ is configured to open within a range of less than an angle at which the light beam is parallel to the light beam (γ>0).

[0068] In this way, the supercharging system 100 according to the present embodiment and the like specifically has a layout in which the exhaust gas released from the bypass passage 31 turns around through the curved exhaust passage 28 and flows into the exhaust purification catalyst 12. The wastegate valve 32 is provided with a bulging portion 62, and this wastegate valve 32 is aligned with the central axis L of the upstream portion 41. １ Therefore, when the turbocharging system 100 according to the present embodiment etc. warms the exhaust purification catalyst 12 with the exhaust gas released from the bypass passage 31, the temperature rise of the exhaust purification catalyst 12 can be made faster than, for example, the first comparative example and the second comparative example.

[0069] In the turbocharging system 100 according to the above embodiment and modified example, when the wastegate valve 32 is closed, the extension line (C １) and an extension line L of the in-course wall 50a of the upstream portion 41 ４ The intersection of and is the first point P １ and an extension line L of the in-course wall 50a of the upstream portion 41 ４ The intersection of the outer wall 51b of the curved portion 42 and the outer wall 51b of the curved portion 42 is referred to as a second point P ２ The wastegate valve 32 is located at an extension line (C ２ ) is the first point P １ and the second point P ２ Line segment P connecting １ -P ２ It is configured to open within the range that intersects with

[0070] In this way, the extension line (C ２ ) is the central axis L of the upstream portion 41 １ In particular, within the range of less than the angle (γ>0) where the line segment P １ -P ２ When the bypass passage 31 is configured to open within the range where the two cross, the temperature rise of the exhaust purification catalyst 12 is particularly likely to be accelerated when the exhaust purification catalyst 12 is heated by the exhaust gas released from the bypass passage 31.

[0071] In the turbocharging system 100 according to the above-described embodiment and modified example, the wastegate valve 32 is disposed on the extension line (C ２ ) may be configured to open in the area where it intersects with the incourse wall 50a of the upstream portion 41.

[0072] In this way, the extension line (C ２ ) is configured to open particularly in the range where it intersects with the inner course wall 50a of the upstream portion 41, diffusion of the exhaust gas is suppressed, and a particularly strong and concentrated exhaust flow is likely to occur along the inner course of the exhaust passage 28. For this reason, high-temperature exhaust gas is likely to be guided into the exhaust passage 28 without heat being absorbed by the curved portion 42 (particularly the outer course wall 51b of the curved portion 42). Therefore, when the exhaust gas purifying catalyst 12 is heated by the exhaust gas escaping from the bypass passage 31, the temperature rise of the exhaust gas purifying catalyst 12 can be particularly accelerated.

[0073] In the turbocharging system 100 according to the above-described embodiment and modified example, the wastegate valve 32 is disposed on the extension line (C ２ ) can be configured to open to a range that passes between the inner wall 50b and the outer wall 51b of the curved portion 42.

[0074] In this way, the extension line (C ２ ) is configured to open to a range that passes between the inner wall 50b and the outer wall 51b of the curved portion 42, in particular, diffusion of the exhaust gas is suppressed, and a strong, concentrated exhaust flow is generated along the inner course of the exhaust passage 28. Furthermore, the flow rate of the exhaust flow is secured. Therefore, a large amount of high-temperature exhaust gas is easily guided into the exhaust passage 28 without heat being absorbed by the curved portion 42 (in particular the outer wall 51b of the curved portion 42). Therefore, when the exhaust gas purifying catalyst 12 is heated by the exhaust gas escaping from the bypass passage 31, the temperature rise of the exhaust gas purifying catalyst 12 can be particularly accelerated.

[0075] In the turbocharging system 100 according to the above-described embodiment and modified example, the wastegate valve 32 is disposed on the extension line (C ２ ) is configured to open until it touches the inside corner.

[0076] In this way, when the wastegate valve 32 is configured to open towards a corner on the inner course of the exhaust passage 28, it is particularly easy to ensure the flow rate of the exhaust flow while generating a strong, concentrated exhaust flow along the inner course of the exhaust passage 28. In other words, the effect of concentrating the exhaust on the inner course and the flow rate of the exhaust are easily optimized. Therefore, when the exhaust purification catalyst 12 is heated by the exhaust gas escaping from the bypass passage 31, the temperature rise of the exhaust purification catalyst 12 can be particularly accelerated.

[0077] In the supercharging system 100 according to the above embodiment and modified example, when the wastegate valve 32 is fully opened, the first point P １ and the second point P ２ Line segment P connecting １ -P ２ and the extension line (C ２) and the angle δ at which they intersect is 15 degrees or more and 60 degrees or less.

[0078] In this way, when the maximum opening degree of the wastegate valve 32 is set so that the angle δ is between 15 degrees and 60 degrees, the diffusion of the exhaust gas is suppressed, and a particularly strong and concentrated exhaust flow is likely to occur along the inner course of the exhaust passage 28. Therefore, when the exhaust gas escaping from the bypass passage 31 warms the exhaust gas purification catalyst 12, the temperature rise of the exhaust gas purification catalyst 12 can be particularly accelerated.

[0079] In the turbocharging system 100 according to the above embodiment and modified example, when the wastegate valve 32 is fully opened, the central axis L of the upstream portion 41 １ and the extension line (C ２ ) and the angle γ formed therebetween is equal to or greater than 15 degrees and equal to or less than 60 degrees.

[0080] In this way, when the maximum opening degree of the wastegate valve 32 is set so that the angle γ is 15 degrees or more and 60 degrees or less, the diffusion of the exhaust gas is suppressed, and a particularly strong and concentrated exhaust flow is likely to occur along the inner course of the exhaust passage 28. Therefore, when the exhaust gas escaping from the bypass passage 31 warms the exhaust gas purification catalyst 12, the temperature rise of the exhaust gas purification catalyst 12 can be particularly accelerated.

[0081] In the turbocharging system 100 according to the above embodiment and modified example, the central axis L of the bypass passage 31 ３ and the central axis L of the downstream portion 43 ２ and are on the same plane, and the central axis L of the upstream portion 41 １ In contrast, the bypass passage 31 and the downstream portion 43 are on the same side.

[0082] In this way, when the exhaust system is designed with a layout in which the flow of exhaust gas escaping from the bypass passage 31 to the exhaust passage 28 makes a particularly large turn (a layout in which the flow essentially makes a U-turn), even if the exhaust flow is concentrated on the inside course, it tends to separate from the inside course walls 50a, 50b when it enters the downstream section 43 and to diffuse within the downstream section 43. For this reason, even when the exhaust flow is concentrated on the inside course, deviations in the temperature of the exhaust flow in the downstream section 43 are suppressed, and exhaust gas with a uniform temperature distribution is introduced into the exhaust purification catalyst 12. Therefore, the temperature of the exhaust purification catalyst 12 rises early and uniformly.

[0083] In the turbocharging system 100 according to the above embodiment and modified example, the central axis L of the upstream portion 41 １ When viewed in the direction of arrow 1, the wastegate valve 32 in the maximum open state is within the range of the upstream portion 41.

[0084] In this way, the central axis L of the upstream portion 41 １ When viewed in the direction of the arrow, if the wastegate valve 32 in a fully open state is within the range of the upstream portion 41, the exhaust flow generated by the bulging portion 62 is not disturbed and is likely to concentrate on the inside course. Therefore, the range in which the exhaust flow hits the curved portion 42 is reduced, and the exhaust flow is less likely to lose heat to the curved portion 42 (particularly the outer course wall 51b). Therefore, when the exhaust gas purifying catalyst 12 is heated by the exhaust gas escaping from the bypass passage 31, the temperature rise of the exhaust gas purifying catalyst 12 can be particularly accelerated.

[0085] In the turbocharging system 100 according to the above embodiment and modified example, the central axis L of the upstream portion 41 １ When viewed in the direction of arrow , the wastegate valve 32 in a closed state is within the range of the upstream portion 41 .

[0086] In this way, the central axis L of the upstream portion 41 １When viewed in the direction of the arrow, if the wastegate valve 32 in a closed state is within the range of the upstream portion 41, the exhaust flow generated by the bulging portion 62 is likely to form a strong flow along the inside course. This reduces the range in which the exhaust hits the curved portion 42, making it difficult for the exhaust flow to lose heat to the curved portion 42 (particularly the outside course wall 51b). Therefore, when the exhaust gas purifying catalyst 12 is heated by the exhaust gas escaping from the bypass passage 31, the temperature rise of the exhaust gas purifying catalyst 12 can be particularly accelerated.

[0087] In the turbocharging system 100 according to the above embodiment and modified example, the central axis L of the upstream portion 41 １ When viewed in the direction of the arrow L, the bypass passage 31 is １ The exhaust passage 28 is connected to the exhaust passage 28 at a position eccentric to the inside of the exhaust passage 28.

[0088] In this way, when the bypass passage 31 is connected to the exhaust passage 28 at a position eccentric to the incourse side, in a normal situation where exhaust is mainly introduced from the turbocharger outlet passage 27 to the exhaust passage 28, the exhaust is smoothly led to the exhaust purification catalyst 12. And, even in a situation where exhaust is mainly introduced from the bypass passage 31 to the exhaust passage 28 in order to warm up the exhaust purification catalyst 12, the exhaust purification catalyst 12 can be warmed up early due to a synergistic effect with the ingenuity in the shape and opening degree of the wastegate valve 32 described above that concentrates the exhaust flow on the incourse.

[0089] In the supercharging system 100 according to the above embodiment and modified example, when the wastegate valve 32 is fully opened, the entire bulge portion 62 is outside the bypass passage 31 .

[0090] In this way, if the shape and expansion amount of the bulging portion 62 are determined so that the entire bulging portion 62 is exposed to the outside of the bypass passage 31 when the wastegate valve 32 is fully open, the bulging portion 62 adjusts the flow path of the exhaust flow while not substantially narrowing the flow path cross-sectional area of ​​the bypass passage 31 when warming the exhaust purification catalyst 12. This ensures the maximum exhaust flow rate. Therefore, the temperature rise of the exhaust purification catalyst 12 can be particularly accelerated.

[0091] In the supercharging system 100 according to the above embodiment and modified example, when the wastegate valve 32 is fully opened, the bulging portion 62 contacts the cross section of the bypass passage 31 at the outlet.

[0092] In this way, if the shape and amount of expansion of the bulging portion 62 are determined so that the bulging portion 62 comes into contact with the cross section at the outlet of the bypass passage 31 when the wastegate valve 32 is fully open, a strong and concentrated exhaust flow is likely to be formed along the inside course while ensuring the maximum exhaust flow rate when warming the exhaust purification catalyst 12. Therefore, the temperature rise of the exhaust purification catalyst 12 can be particularly accelerated.

[0093] The control methods for supercharging systems according to the above embodiments and modified examples (particularly the control methods for supercharging systems according to modified examples) are control methods for a supercharging system 100 having an internal combustion engine 10, a supercharger 11 that compresses intake air of the internal combustion engine 10 using exhaust gas from the internal combustion engine 10, an exhaust purification catalyst 12 that purifies the exhaust gas, an exhaust passage 28 that guides exhaust gas from the supercharger 11 to the exhaust purification catalyst 12, a bypass passage 31 that guides the exhaust gas to the exhaust passage 28 without passing through the supercharger 11, a wastegate valve 32 that opens and closes the bypass passage 31, and a controller that controls the opening and closing of the wastegate valve 32. In this supercharging system 100, the exhaust passage 28 forms a curve by having an upstream section 41 into which exhaust gas flows from the supercharger 11 or the bypass passage 31, a curved section 42 that changes the direction of the exhaust gas that has flowed into the upstream section 41, and a downstream section 43 that connects the curved section 42 and the exhaust purification catalyst 12. The wastegate valve 32 has a bulging portion 62 that bulges into the bypass passage 31 when the bypass passage 31 is closed. The wastegate valve 32 is configured to swing open at the outlet of the bypass passage 31 toward downstream and away from the inside of the curve. When warming up the exhaust purification catalyst 12, the controller 33 swings the wastegate valve 32 so that the central axis L of the upstream portion 41 is aligned with the central axis L of the upstream portion 41. １ It opens within an angle less than that which is parallel to the

[0094] In this way, when the exhaust purification catalyst 12 is warmed, the wastegate valve 32 is moved by the control of the controller 33 so as to be aligned with the central axis L of the upstream portion 41. １If the wastegate valve 32 is configured to open within a range of an angle less than that at which it is parallel to the arrow A, the temperature rise of the exhaust purification catalyst 12 can be accelerated even when the maximum opening degree of the wastegate valve 32 is not limited by a mechanical mechanism.

[0095] Although the embodiments of the present invention have been described above, the configurations described in the above embodiments and modifications merely show some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention.

[0096] This application claims priority based on Japanese Patent Application No. 2023-116091, filed with the Japan Patent Office on July 14, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A turbocharging system having an internal combustion engine, a turbocharger that compresses intake air of the internal combustion engine with exhaust from the internal combustion engine, an exhaust purification catalyst that purifies the exhaust, an exhaust passage that guides the exhaust from the turbocharger to the exhaust purification catalyst, a bypass passage that guides the exhaust to the exhaust passage without passing through the turbocharger, and a wastegate valve that opens and closes the bypass passage, wherein the exhaust passage forms a curve with an upstream section into which the exhaust flows from the turbocharger or the bypass passage, a curved section that changes the direction of the exhaust that has flowed into the upstream section, and a downstream section that connects the curved section and the exhaust purification catalyst, the wastegate valve has a bulging section that bulges into the bypass passage when the bypass passage is closed, the wastegate valve is configured to swing open at an outlet of the bypass passage toward downstream, away from the inside of the curve, and the wastegate valve is configured to open within a range of an angle less than that which is parallel to a central axis of the upstream section.

2. A turbocharging system as described in claim 1, wherein when the wastegate valve is closed, the intersection of an extension line of the wastegate valve and an extension line of the incourse wall of the upstream portion is defined as a first point, and the intersection of an extension line of the incourse wall of the upstream portion and the outcourse wall of the curved portion is defined as a second point, and the wastegate valve opens within a range where an extension line of the wastegate valve intersects with a line segment connecting the first point and the second point.

3. A turbocharging system according to claim 2, wherein the wastegate valve is configured to open in a range where an extension line of the wastegate valve intersects with the in-course wall of the upstream portion.

4. A turbocharging system according to claim 2, wherein the wastegate valve is configured to open to a range where an extension line of the wastegate valve passes between the inner course wall and the outer course wall of the curved portion.

5. A turbocharging system according to claim 2, wherein the wastegate valve is configured to open until an extension line of the wastegate valve contacts a corner of the inside course.

6. A turbocharging system as claimed in claim 2, wherein, when the wastegate valve is fully open, the angle at which the line segment connecting the first point and the second point intersects with an extension of the wastegate valve is between 15 degrees and 60 degrees.

7. A turbocharging system according to claim 2, wherein, when the wastegate valve is fully open, the angle between the central axis of the upstream portion and an extension line of the wastegate valve is equal to or greater than 15 degrees and equal to or less than 60 degrees.

8. A turbocharging system according to claim 1, wherein a central axis of the bypass passage and a central axis of the downstream portion are on the same plane, and the bypass passage and the downstream portion are on the same side of the central axis of the upstream portion.

9. A turbocharging system according to claim 1, wherein the wastegate valve in its maximum open state is within the range of the upstream portion when viewed in the direction of the central axis of the upstream portion.

10. A turbocharging system according to claim 9, wherein the wastegate valve in a closed state is within the range of the upstream portion when viewed in the direction of the central axis of the upstream portion.

11. A turbocharging system as claimed in claim 1, wherein, when viewed in the direction of the central axis of the upstream portion, the bypass passage is connected to the exhaust passage at a position eccentric to the incourse side relative to the central axis of the upstream portion.

12. A turbocharging system according to claim 1, wherein when the wastegate valve is fully opened, the bulging portion is entirely outside the bypass passage.

13. A supercharging system according to claim 12, wherein, when the wastegate valve is fully opened, the bulge contacts a cross section at the outlet of the bypass passage.

14. A control method for a turbocharging system having an internal combustion engine, a turbocharger that compresses intake air of the internal combustion engine with exhaust gas from the internal combustion engine, an exhaust purification catalyst that purifies the exhaust gas, an exhaust passage that leads the exhaust gas from the turbocharger to the exhaust purification catalyst, a bypass passage that leads the exhaust gas to the exhaust passage without passing through the turbocharger, a wastegate valve that opens and closes the bypass passage, and a controller that controls the opening and closing of the wastegate valve, wherein the exhaust passage forms a curve with an upstream portion into which the exhaust gas flows from the turbocharger or the bypass passage, a curved portion that changes the direction of the exhaust gas that has flowed into the upstream portion, and a downstream portion that connects the curved portion and the exhaust purification catalyst, the wastegate valve has a bulging portion that bulges into the bypass passage when the bypass passage is closed, and the wastegate valve is configured to swing open at the outlet of the bypass passage toward downstream, away from the inside of the curve, a control method for a supercharging system, the control device opening the wastegate valve within a range less than an angle parallel to a central axis of the upstream portion when the exhaust purification catalyst is warmed up.

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