TURBINE

Abstract

A turbine comprising a wastegate chamber (28); a turbine housing (12) defining a turbine inlet (14), the turbine housing (12) comprising: a wastegate inlet passage (30) defining a flow path between the turbine inlet (14) and the wastegate chamber (28), the wastegate inlet passage (30) comprising a turbine port (38) proximal to the turbine inlet (14) and a non-circular valve port (36) proximal to the wastegate chamber (28), and a raised rim (52) surrounding the non-circular valve port (36) and conforming to the shape of the non-circular valve port (36), the raised rim (52) comprising a first sealing surface;and a valve element (42) comprising a second sealing surface (50), the valve element (42) being movable between a closed position in which the second sealing surface (50) forms a seal with the first sealing surface (54) to prevent fluid flow along the flow path, and an open position in which the second sealing surface (50) is spaced from the first sealing surface (54) to allow fluid flow along the flow path;

Description

[0001] The present disclosure relates to a turbine, for example, in a turbocharger or other turbomachine. More particularly, the present disclosure relates to a turbine with a wastegate having a wastegate inlet passage with a non-circular valve port.

[0002] Turbines convert the potential energy of a fluid into mechanical work. Conventional turbines comprise a turbine casing defining a turbine inlet, a turbine chamber, and a turbine outlet. A turbine wheel is mounted within the turbine chamber. The turbine inlet commonly comprises an annular inlet defined between opposing radial walls disposed around the turbine chamber and an inlet volute disposed around the annular inlet. In use, fluid enters the turbine through the turbine inlet, where it is directed to the turbine wheel within the turbine chamber. The fluid impacts one or more blades defined by the turbine wheel, thus exerting a force on the turbine wheel, causing the turbine wheel to rotate. Once the fluid passes through the turbine wheel, it exits the turbine via the turbine outlet.

[0003] Turbochargers are well-known turbomachines for supplying air to the intake of an internal combustion engine at pressures above atmospheric pressure (boost pressures). Turbochargers increase the pressure of atmospheric air entering an internal combustion engine using a turbine and compressor mounted on a common shaft. Exhaust gases from an internal combustion engine's exhaust manifold are passed through the turbine. Rotation of the turbine wheel causes the shaft and thus the compressor wheel to rotate. Air is drawn through the compressor and compressed by the compressor wheel to a boost pressure. By providing higher-pressure air to the internal combustion engine, more oxygen is available within the internal combustion engine for fuel combustion. Therefore, the turbocharger allows more fuel to be burned, and consequently, the internal combustion engine can produce more power.

[0004] It is known to provide a turbine with a bypass, typically referred to as a wastegate, that allows fluid to flow from the turbine inlet to the turbine outlet without passing through the turbine wheel. Wastegates are typically provided with a wastegate valve (e.g., a poppet valve or a swing valve) configured to allow or prevent flow from bypassing the turbine wheel.

[0005] The wastegate includes a wastegate chamber within which the wastegate valve is located. The wastegate chamber is commonly defined at least partially by the turbine housing. The wastegate further includes a wastegate inlet passage extending through the turbine housing between the turbine inlet and the wastegate chamber. The end of the wastegate inlet passage proximal to the turbine inlet is referred to herein as the turbine port, and the end of the wastegate inlet passage proximal to the wastegate chamber is referred to herein as the valve port. The wastegate inlet passage provides a fluid flow path between the turbine inlet and the wastegate chamber. The wastegate further includes a wastegate outlet providing a fluid flow path between the wastegate chamber and the turbine outlet or the atmosphere.

[0006] The wastegate valve includes a valve element that is movable within the wastegate chamber. For example, if the wastegate is a swing-type valve, the valve element may be mounted on an arm that is rotatable about a pivot mounted on the wastegate chamber and spaced from the wastegate valve. The wastegate is closed by moving the valve element to an advanced position where it blocks the valve port of the wastegate inlet passage, thereby preventing gas from entering the wastegate chamber and ensuring that the gas impinges on the turbine wheel. The wastegate is opened by moving the valve element away from the valve port of the wastegate inlet passage to a retracted position. This allows gas from the turbine to enter the wastegate chamber through the wastegate inlet passage between the valve element and the wall of the wastegate chamber, thereby bypassing the turbine wheel.

[0007] When used in a turbocharger, the wastegate is opened to allow fluid to bypass the turbine wheel when the boost pressure of the fluid in the compressor outlet rises above a predetermined level. An actuator closes the wastegate by moving the wastegate valve to the advanced position and retaining it there. The actuator force required to hold the valve element in the advanced position and thus keep the wastegate closed is dependent on the fluid force acting on the valve element in the turbine at the valve port, which is balanced by the actuator force. The fluid force is proportional to the area of ​​the valve element acted upon by the fluid. The area of ​​the valve element acted upon by the fluid depends on the location of the seal formed by the valve element around the valve port.This range can be difficult to predict if the location of the seal between the valve element and the wall of the wastegate chamber is poorly defined, for example due to large component manufacturing tolerances.

[0008] EP2489853A1 relates to a wastegate comprising a wastegate inlet passage having a circular cross-section and an axis extending perpendicular to the surface of the wastegate chamber wall against which the valve element seals. Thus, the wastegate has a circular valve port. The valve element takes the form of a disc. It is disclosed that either the valve element or the wastegate chamber wall surrounding the circular valve port may include a raised annular rim defining a sealing surface. This sealing surface is intended to reduce the occurrence of fluid leakage from the bypass passage between the valve element and the wastegate chamber wall. Fluid leakage from the bypass passage into the wastegate chamber when the wastegate is closed may have an adverse effect on the performance and / or efficiency of the turbine and / or turbocharger.

[0009] It is an object of the present disclosure to provide an improved wastegate having a non-circular valve port, which may provide, for example, greater packaging flexibility, simpler device, improved efficiency, greater accuracy in tuning or operation, etc.

[0010] According to a first aspect, a turbine is provided that includes a wastegate chamber. The turbine further includes a turbine housing. The turbine housing defines a turbine inlet. The turbine housing includes a wastegate inlet passage. The wastegate inlet passage defines a flow path between the turbine inlet and the wastegate chamber. The wastegate inlet passage includes a turbine port proximal to the turbine inlet and a non-circular valve port proximal to the wastegate chamber. The turbine housing further includes a raised rim surrounding the non-circular valve port and conforming closely to the shape of the non-circular valve port. The raised rim includes a first sealing surface. The turbine further includes a valve element. The valve element includes a second sealing surface.The valve element is movable between a closed position in which the second sealing surface forms a seal with the first sealing surface to prevent fluid flow along the flow path and an open position in which the second sealing surface is spaced from the first sealing surface to allow fluid flow along the flow path.

[0011] The non-circular valve port can allow greater flexibility in accommodating the wastegate and turbine, expanding machining options.

[0012] Advantageously, the first sealing surface of the raised rim can provide a controlled sealing location between the valve element and the turbine housing. This can enable accurate prediction of the area of ​​the valve element that will be acted upon by fluid pressure from the valve port when the valve element is in the closed position. As a result, an actuator controlling the wastegate can be tuned with greater accuracy to move the valve element between the closed and open positions at the appropriate times. Furthermore, the presence of a controlled contact area between the valve element and the housing via the raised rim can provide improved sealing. Improved sealing leads to improved turbine efficiency when the valve element is in the closed position.

[0013] The non-circular valve port may have a larger dimension defined by a maximum distance between opposing points on the valve port. The second sealing surface may have a smaller dimension defined by a minimum distance between opposing points on an outer edge of the second sealing surface. The smaller dimension of the second sealing surface may be larger than the larger dimension of the non-circular valve port.

[0014] The fact that the minor dimension of the second sealing surface is larger than the major dimension of the non-circular valve port, such that the second sealing surface on the valve element forms a seal with the first sealing surface on the raised edge, can enable the valve element to be manufactured to close tolerances without compromising wastegate function or turbine efficiency. Provided that the minor dimension of the second sealing surface is larger than the major dimension of the non-circular valve port, the second sealing surface can form a seal with the first sealing surface, regardless of how much larger the minor dimension of the second sealing surface is compared to the minor dimension of the non-circular valve port.Furthermore, the relative dimensions of the valve port and the valve element may allow for a simple wastegate arrangement without the need for an anti-rotation feature to prevent the valve element from rotating relative to the raised rim. A seal may be formed when the first and second sealing surfaces are in contact, regardless of the orientation of the valve element relative to the raised rim. The second sealing surface may define a valve axis through its center, and the valve element may freely rotate about the valve axis. The fact that the valve element can rotate freely may reduce uneven wear on the sealing surface of the valve element.

[0015] The non-circular valve port may define a plane. The wastegate inlet passage may extend along a passage axis that is at an oblique angle to the plane of the non-circular valve port.

[0016] Usefully, a favorable angle of the flow path through the wastegate inlet passage from the turbine inlet can be achieved, thereby improving the wastegate discharge coefficient and the operation of the turbine and / or turbocharger. Furthermore, the oblique angle of the wastegate inlet passage relative to the valve port allows for greater flexibility in the packaging of the wastegate and turbine, expanding machining options.

[0017] The larger dimension of the non-circular valve connection can be at least 15 mm. The larger dimension of the non-circular valve connection can be up to 40 mm.

[0018] The wastegate inlet passage may have a non-circular axial cross-section, i.e., elliptical, teardrop-shaped, pear-shaped, square, or irregularly shaped. Alternatively, the wastegate inlet passage may have a circular axial cross-section.

[0019] The shape of the non-circular valve port may have the same shape as the axial cross-section of the wastegate inlet passage if the passage axis is perpendicular to the plane of the valve port. Alternatively, the shape of the non-circular valve port may differ from the shape of the axial cross-section of the wastegate inlet passage if the passage axis is at an oblique angle to the plane of the valve port.

[0020] The non-circular valve port may be elliptical, teardrop-shaped, pear-shaped, square, or irregularly shaped. The valve port may be shaped to optimize gas flow through the valve port when the valve element is in the open position. The valve port may be shaped to allow for alternative wastegate housing arrangements.

[0021] If the valve port has an elliptical shape, the elliptical valve port may be defined by a larger diameter and a smaller diameter. The larger dimension of the elliptical valve port may be the larger diameter. The first sealing surface may have the shape of an elliptical ring.

[0022] The first sealing surface may have a constant width. The larger dimension of the first sealing surface may be equivalent to the larger dimension of the valve port plus twice the width of the first sealing surface. The width of the sealing surface may be between 1 mm and 5 mm. Usefully, the sealing surface has an optimal width that is large enough to be sufficiently resistant to the environment within the turbine and hot gases that may pass through the wastegate, yet small enough to provide an accurate sealing position so that the gas force acting on the valve element in the closed position can be accurately estimated and the wastegate actuator can be precisely tuned. Furthermore, minimizing the width of the land reduces the amount of free space around the valve port required to provide line of sight and access during machining.

[0023] The second sealing surface may be circular. The smaller dimension of the second sealing surface may be the diameter of the second sealing surface.

[0024] Usefully, a standard valve can be used. Furthermore, the valve element can be manufactured to large tolerances without compromising wastegate function or turbine efficiency.

[0025] The first sealing surface may have a larger dimension defined by a maximum distance between opposing points on an outer edge of the sealing surface. The smaller dimension of the second sealing surface may be larger than the larger dimension of the first sealing surface.

[0026] If the valve port is elliptical, the raised rim may be in the shape of an elliptical ring. The elliptical outer edge of the first sealing surface may be defined by a major diameter and a minor diameter. The larger dimension of the elliptical outer edge of the first sealing surface may be its larger diameter. If the first sealing surface has a constant width, the larger dimension of the first sealing surface may be equivalent to the larger dimension of the valve port plus twice the width of the first sealing surface.

[0027] The first sealing surface may be coplanar with the valve connection.

[0028] The first sealing surface may be tapered away from the valve port. The first sealing surface may be angled relative to the plane of the valve port. The first sealing surface may be angled away from the valve port. The first sealing surface may take the shape of a flat truncated cone. When the valve element is in the closed position, a portion of the first sealing surface near the inner edge of the first sealing surface may sealingly engage the second sealing surface. When the valve element is in the closed position, the inner edge of the first sealing surface may embed itself into the second sealing surface. Usefully, the tapered sealing surface controls the location of the seal formed between the first and second sealing surfaces (near the inner edge of the first sealing surface).Controlling the location of the seal allows for accurate calculation of the area of ​​the valve element affected by the valve port fluid pressure, therefore the wastegate actuator can be finely tuned to improve wastegate efficiency and / or prevent leakage through the wastegate, which can reduce turbine efficiency.

[0029] The first sealing surface can be flat or concave.

[0030] The raised rim may be formed in the turbine housing by interpolation milling. The wastegate inlet passage may be formed in the turbine housing by interpolation milling.

[0031] Usefully, interpolation milling can allow the valve port and raised rim to be machined to tight tolerances. The presence of a valve port and raised rim with tight tolerances allows for accurate calculation of the area of ​​the valve element impacted by the valve port fluid pressure. Therefore, the wastegate actuator can be precisely tuned to improve wastegate efficiency and / or prevent wastegate leakage, which can reduce turbine efficiency.

[0032] The wastegate inlet passage may be formed in the turbine housing by 5-axis milling. The raised rim may be formed in the turbine housing by 5-axis milling or turning. Usefully, manufacturing by 5-axis milling may allow the first sealing surface to be formed as a flat truncated cone and / or the wastegate inlet passage to be formed along an axis that is not coaxial with the raised rim.

[0033] According to a second aspect, a turbocharger is provided comprising the turbine of the first aspect.

[0034] Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Fig. is a schematic cross-sectional view of a turbine and wastegate according to an embodiment of the present invention; Fig. a schematic cross-sectional view of a wastegate inlet passage and a valve element of the wastegate of Fig. is; Fig. a plan view of the wastegate inlet passage and the wastegate valve element of Fig. is; Fig. a perspective cross-sectional view of the turbine and wastegate of Fig. with the wastegate valve in a closed configuration; Fig. a perspective cross-sectional view of the wastegate inlet passage and the wastegate valve element of Fig. with the wastegate valve in an open configuration; Fig. is a cutaway perspective view of a turbocharger incorporating a wastegate according to the present invention; Fig. is a schematic cross-sectional view of an actuator for controlling a wastegate according to the present invention; Fig. is a sectional view of a turbine and a wastegate according to another embodiment of the present invention; Fig. a side view of the wastegate inlet passage of Fig. is; Fig. a detailed view of the raised edge of Fig. is; Fig. is a sectional view of a turbine and a wastegate according to another embodiment of the present invention; Fig. a side view of the wastegate inlet passage of Fig. is; Fig. a detailed view of the raised edge of Fig. is; Fig. is a sectional view of a turbine and a wastegate according to another embodiment of the present invention; Fig. a side view of the wastegate inlet passage of Fig. is; and Fig. a detailed view of the raised edge of Fig. is.With reference to Fig. A turbine 10 comprises a turbine housing 12 defining a turbine inlet 14, a turbine chamber 16, and a turbine outlet 18. The turbine further comprises a turbine wheel 20 disposed within the turbine chamber 16 and rotating about a turbine axis a t is rotatable on a shaft 24. In use, a conventional flow path A is provided through the turbine. Fluid flows into the turbine 10 via the turbine inlet 14 and impinges on the turbine wheel 20, causing rotation of the turbine wheel 20 about the turbine axis a t The fluid is redirected through the turbine wheel 20 to flow out of the turbine 10 via the turbine outlet 18.

[0035] In order to regulate the volume of fluid impinging on the turbine wheel 20 and therefore to control the rotational speed of the turbine wheel 20, the turbine is provided with a wastegate 26 defining a bypass flow path B. The wastegate 26 provides a way to control the speed of the turbine wheel 20 by selectively diverting an amount of exhaust gas away from the turbine wheel 20.

[0036] The wastegate 26 includes a wastegate chamber 28 having a chamber inlet 30 and a chamber outlet 32. The chamber inlet 30 provides a flowpath between the turbine inlet 14 and the wastegate chamber 28. The chamber outlet 32 ​​provides a flowpath between the wastegate chamber 28 and the turbine outlet 18. Fluid flowing along the bypass flowpath B flows from the turbine inlet 14, through the chamber inlet 30 to the wastegate chamber, and through the chamber outlet 32 ​​to the turbine outlet 18. In other embodiments, the chamber outlet may provide a flowpath between the wastegate chamber and the atmosphere, and the bypass flowpath may terminate in the atmosphere instead of the turbine outlet.

[0037] The wastegate 26 further comprises a wastegate valve 34. The wastegate valve 34 comprises a shaft 40 and a valve element 42 which is connected to the shaft 40 via an arm 44 (see Fig. ). The valve element 42 is mounted on the arm via a pin 46. The wastegate valve 34 has a valve axis a v which extends through the center of the pin 46 and the valve element 42. The valve element 42 can rotate freely about the valve axis a v The fact that the valve element 42 can rotate freely can reduce uneven wear on the valve element 42

[0038] The wastegate valve 34 has an open configuration and a closed configuration to control fluid flow along the bypass flow path B. The wastegate valve 34 is movable between the open and closed configurations by an actuator 35. The shaft 40 is connected to the actuator 35, which controls the wastegate valve 34 between the open and closed configurations via the shaft. Specifically, the shaft 40 is rotatable by the actuator 35 to move the valve element 42 between a closed position (see Fig. , in which the valve element 42 blocks the chamber inlet 30 to prevent fluid flow along the bypass flow path B, and an open position (see Fig. in which the valve element 42 is spaced from the chamber inlet to allow fluid flow along the bypass flow path B.

[0039] Fig. shows the chamber inlet 30 and the wastegate valve 34 in more detail. The chamber inlet 30 is a passage, referred to herein as a wastegate inlet passage, formed in the turbine housing 12. The wastegate inlet passage 30 has a passage axis a p The wastegate inlet passage extends through the turbine housing along the passage axis a pbetween a valve port 36 proximal to the wastegate chamber 28, and a turbine port 38 proximal to the turbine inlet 14. The turbine housing 12 includes a raised rim 52 surrounding the valve port 36. The raised rim 52 and the wastegate inlet passage 30 are formed in the turbine housing 12 by interpolation milling (other types of machining may be used to form the raised rim). The raised rim 52 is closely contoured to the valve port 36. Thus, the inner surface of the raised rim 52 provides a small extension for the wastegate inlet passage 30. The raised rim 52 defines a sealing surface 54, which is a first sealing surface of the wastegate 26. The sealing surface 54 of the raised rim 52 is flat. The sealing surface 54 of the raised rim 52 is coplanar with the valve port 36. The sealing surface 54 is defined between an outer edge 56 and an inner edge 58.The inner edge 58 corresponds to the valve port 36. The valve element 50 also includes a sealing surface 50, which is a second sealing surface of the wastegate 26. The sealing surface 50 of the valve element 50 is flat. As described with reference to FIG. Fig. As will be described in more detail, the sealing surface 50 of the valve element 42 and the sealing surface 54 of the raised rim 52 can be sealingly engaged to block fluid flow along the bypass flow path B.

[0040] With continued reference to Fig. The sealing surface 54 of the raised rim 52, the valve port 36 and the turbine port 38 define parallel planes. The passage axis a pis at an oblique angle to the plane of the sealing surface 54, the plane of the valve port 36, and the plane of the turbine port 38. The fact that the wastegate inlet passage 30 is angled allows flexibility in the packaging arrangement of the turbine 10 and the wastegate 26. The fact that the wastegate inlet passage 30 is angled relative to the plane of the turbine port 38 can also provide a preferred flow angle for fluid flowing along the bypass flowpath B from the turbine inlet 14.

[0041] The wastegate inlet passage 30 has a circular cross-section when viewed transversely to the passage axis a p As in Fig. As can be seen, the valve port 36 has an elliptical shape as a result of the wastegate inlet passage 30 having a circular axial cross-section and extending along an axis at an oblique angle relative to the plane of the valve port 36. The valve port 36 is defined by a larger dimension, which in the illustrated example is a larger port diameter d p1 of the elliptical valve port 36, and a smaller dimension, which in the example shown is a smaller port diameter d p2of the elliptical valve port 36. The sealing surface 54 of the raised rim 52 has an elliptical annular shape. The outer and inner edges 56, 58 are elliptical. The sealing surface 54 of the raised rim is defined by a width W between the outer and inner edges 56, 58. The width W of the sealing surface 54 is constant. The width W of the sealing surface 54 is small in relation to the larger and smaller port diameters d p1 , d p2. The width W of the sealing surface 54 can be between 1 mm and 5 mm. Preferably, as in the present embodiment, the width W of the sealing surface 54 is between 1 mm and 3 mm. The preferred width W of the sealing surface 54 provides an optimal width that is large enough to be sufficiently resistant to the environment within the turbine and hot gases that may pass through the wastegate, and small enough to provide an accurate sealing location, as will be discussed in more detail below. Furthermore, minimizing the width of the land reduces the amount of free space around the valve port required to provide a line of sight and access during machining. The outer edge 56 of the sealing surface 54 is defined by a larger dimension, which in the illustrated example is a larger diameter d s1the elliptical outer edge 56, and a smaller dimension, which in the example shown is a smaller diameter d s2 the elliptical outer edge 56, where d s1 - d p1 + 2W and d s2 = d p2 + 2W.

[0042] With reference to Fig. In combination, the valve element 42 takes the shape of a disc and has a circular sealing surface 50. In other embodiments, the sealing surface of the valve element may be non-circular. In other embodiments, the sealing surface of the valve element may have the same shape as the valve port. If the sealing surface of the valve element is non-circular, rotation of the valve element about the valve axis may be prevented by an anti-rotation feature, e.g., an anti-rotation pin or the like, thus ensuring that the non-circular sealing surface of the valve element remains properly aligned relative to the non-circular valve port. The valve sealing surface 50 is defined by a minor dimension, which in the illustrated example is the diameter D of the circular sealing surface. The diameter D is equal to or greater than the major diameter dp1 of the valve connection. Preferably, as in the present embodiment, the diameter D is also as large as or larger than the larger diameter d s1the outer edge 56 of the sealing surface 54 defined by the raised rim 52. In other embodiments, the valve element may have a non-circular sealing surface, in which case the minor dimension is a minimum distance between opposing points on an outer edge of the sealing surface. The minor dimension is as large as or greater than the major dimension of the valve port. Preferably, the minor dimension is also as large as or greater than the major dimension of the outer edge of the sealing surface defined by the raised rim. The relative dimensions of the sealing surface 50 of the valve element 42 and at least the valve port 36 ensure that the valve element 42 can completely cover the valve port 36, regardless of the rotational position of the valve element 42 about the valve axis a vand although the valve port 36 has a planar shape different from the shape of the sealing surface 50 of the valve element 52.

[0043] Fig. show the wastegate valve 34 in the closed and open configurations, respectively. When the wastegate valve 34 is in the closed configuration, as shown in Fig. , the valve element 42 is in the closed position. The valve element 42 abuts the raised edge 52 in its closed position. The center of the sealing surface 50 of the valve element 42 is generally aligned with the center of the valve port 36, that is, the point at which the valve axis a v intersects the sealing surface 50 of the valve element 42, coincides with the point at which the passage axis a pintersects the valve port 36. The sealing surfaces 50, 54 are sealingly engaged to prevent fluid flow through the valve port 36, thus fluid cannot flow from the wastegate inlet passage 30 to the wastegate chamber 28, and the bypass flow path B is blocked. When the wastegate valve 34 is in the open configuration, as shown in Fig. , the valve element 42 is in the open position. When the valve element 42 is in the open position, the sealing surface 50 of the valve element 42 is spaced from the sealing surface 54 of the raised rim 52. Fluid flow through the valve port 36 from the wastegate inlet passage 30 to the wastegate chamber 28 is not impeded. Instead, fluid flow from the wastegate inlet passage 30 to the wastegate chamber 28 is permitted between the raised rim 52 and the valve element 42. Thus, fluid flow along the bypass flowpath is permitted.

[0044] The wastegate valve 34 is moved from the closed configuration to the open configuration, and the valve element is moved from the closed position to the open position by the shaft 40 which is mounted on an actuating axis a athrough the center of the shaft 40. The rotation of the shaft 40 causes the arm 44 and therefore also the valve element 42 to rotate about the actuating axis a a turn.

[0045] The valve element 42 moves through an angle of rotation sufficient to provide clearance between the sealing surface 50 of the valve element 42 and the sealing surface 54 of the raised rim 52. This type of valve is referred to as a swing valve. In other embodiments, other types of valves, such as a poppet valve, may be used.

[0046] Fig. shows the wastegate 26 implemented in a turbocharger 60. The turbocharger 60 includes a turbine 100 substantially similar to the previously described turbine 10, except that the turbine inlet 114 includes a twin scroll 115. In other embodiments, the turbocharger may include the turbine 10. The twin scroll 115 includes a first passage 115a and a second passage 115b, both of which are in fluid communication with the turbine wheel 120. The bypass flow path B extends from the first passage 115a of the twin scroll to the turbine outlet 118. The turbocharger 60 further includes a compressor 62 and a bearing assembly 64. The compressor 62 includes a compressor housing 66 defining a compressor inlet 68, a compressor chamber 70, a compressor scroll 78, and a compressor outlet 72. A compressor wheel 74 is located within the compressor chamber 70.The compressor wheel 74 is mounted on the shaft 124, on which the turbine wheel 120 is also mounted, so that the compressor wheel 74 and the turbine wheel 120 rotate together. The bearing assembly 64 includes bearings 76 within a bearing housing 77. The bearings 76 support the shaft 124 between the compressor wheel 74 and the turbine wheel 20. The bearing housing 77 is coupled between the turbine housing 112 and the compressor housing 66.

[0047] Exhaust gases from an internal combustion engine (not shown) are directed to the turbine 100. The exhaust gases enter the turbine inlet 114, which is defined by the turbine housing 112. The exhaust gases impinge on the turbine wheel 120, causing rotation of the turbine wheel 120 about the turbine axis a t Rotation of the turbine wheel 120 drives rotation of the shaft 124 and therefore rotation of the compressor wheel 74.

[0048] Rotation of the compressor wheel 74 causes air to be drawn from the atmosphere into the compressor inlet 68. The air passes through the compressor wheel 74 and enters the compressor scroll 78, which is defined by the compressor housing 66. Due to the kinetic energy imparted to the incoming air by the compressor wheel 74, the air in the compressor scroll 78 is at a higher pressure than the air entering the compressor inlet 68. The compressed air exits the compressor 62 via the compressor outlet 72, where it is fed to an intake manifold of the internal combustion engine (not shown).

[0049] The wastegate 26 reduces the amount of exhaust gas impinging on the turbine wheel 20 by providing the bypass flowpath B from the turbine inlet 114 to the turbine outlet 118, and therefore regulates the rotation of the turbine wheel 120. When the wastegate 26 is used in the turbocharger 60, this control of the rotation of the turbine wheel 20 translates into control of the boost pressure of the compressed air exiting the compressor 62. This provides advantages in preventing adverse flow conditions in the compressor, for example, compressor surge.

[0050] Wastegates according to embodiments of the invention can be actuated by a variety of means, including hydraulic or electric actuators. The turbocharger 60 includes a pneumatic actuator 35. The actuator 35 provides control of the wastegate 26 according to the boost pressure of the compressed air provided by the compressor 62. The actuator 35 includes a control assembly 37 and an operating arm 79. A first end of the operating arm 79 is coupled to the control assembly 37 such that the control assembly 37 can control bidirectional axial movement of the operating arm 79. A second end of the operating arm 79 is coupled to the shaft 40 of the wastegate 26 via a linkage 41. The linkage 41 converts the axial movement of the operating arm 79 into rotation of the shaft 40.Axial movement of the operating arm 79 in a first direction causes rotation of the shaft 40 to move the valve element 42 from a closed position to an open position. Axial movement of the operating arm 79 in a second direction, opposite the first direction, causes rotation of the shaft 40 to move the valve element 42 from the open position to the closed position. Other linkage arrangements and other actuation arrangements may be used.

[0051] With reference to Fig. The control assembly 37 includes a biasing member 80, i.e., a spring that biases the operating arm 79 in the second direction to maintain the valve element 42 in the closed position, and a diaphragm 82 exposed to the boost pressure of the compressed air exiting the compressor 62 via a pressure signal tube 81. The operating arm 79 is moved in the first direction to move the valve element 42 to the open position when the combination of the boost pressure acting on the diaphragm 82 and the pressure of the exhaust gas in the wastegate inlet passage 30 acting on the valve element 42 in the closed position overcomes the bias of the spring 80.

[0052] When tuning the actuator 35 before it is assembled with the turbine, air is applied to the diaphragm 82 to move the valve element 42 away from the valve port 36 to the open position, and the pressure of the exhaust gas in the wastegate inlet passage 30 acting on the valve element 42 is assumed based on a nominal geometry of the turbine and wastegate to determine the appropriate spring force required. Therefore, to tune the actuator 35 to open at a predetermined boost pressure acting on the diaphragm 82, the pressure of the exhaust gas in the wastegate inlet passage 30 acting on the valve element 42 should be predicted. The pressure of the exhaust gas in the wastegate inlet passage 30 acting on the valve element 42 directly corresponds to the effective area of ​​the valve element 42 acted upon by the exhaust gases.The effective area of ​​the valve element 42 exposed to the exhaust gases depends on the location at which the seal is formed between the sealing surface 50 of the valve element 42 and the sealing surface 54 of the raised rim 52. The sealing location can be anywhere where the sealing surface 50 of the valve element 42 is in contact with the sealing surface 54 of the raised rim 52 between the inner and outer edges 58, 56 of the sealing surface 54 of the raised rim 52. The effective area consists of a known portion, which is the area of ​​the valve port 36, plus an unknown portion, which is an undetermined area of ​​the sealing surface 54 of the raised rim 52 with which the sealing surface 50 of the valve element 42 is in contact, depending on the sealing location.The fact that the width W of the sealing surface 54 of the raised edge 52 in relation to the larger and smaller diameters d. p1 , d p2of the valve port 36 is small, resulting in the unknown portion of the effective area being small relative to the known portion of the effective area; for example, the unknown portion of the effective area may be 10% of the known portion of the effective area. Accordingly, by controlling the geometry of the port and sealing surfaces, the uncertainty and error margin in predicting the effective area are reduced, and thus, predicting the pressure of the exhaust gas in the wastegate inlet passage 30 acting on the valve element 42 is reduced, allowing the actuator 35 to be tuned with greater accuracy. Furthermore, product-to-product variation is reduced.By precisely tuning the actuator 35, the risk of the wastegate being moved between the open and closed configurations at inappropriate times is reduced and the associated adverse effects on turbocharger performance are mitigated.

[0053] Fig. show an alternative turbine 210 provided with a wastegate 226. The turbine 210 and the wastegate 226 are substantially the same as the turbine 10 and the wastegate 26, except for the features described. Like features are designated by like reference numerals increased by 200.

[0054] The turbine 210 includes a turbine housing 212 defining a turbine inlet 214. In use, a conventional flowpath is provided through the turbine. Fluid flows into the turbine 210 via the turbine inlet 214 and impinges on a turbine wheel, causing the turbine wheel to rotate. The fluid is bypassed by the turbine wheel to flow out of the turbine 210 via a turbine outlet. To regulate the volume of fluid impinging on the turbine wheel and therefore control the rotational speed of the turbine wheel, the turbine is provided with a wastegate 226 defining a bypass flowpath and selectively diverting exhaust gas away from the turbine wheel. The wastegate 226 includes a wastegate chamber 228 having a chamber inlet 230 and a chamber outlet. The wastegate 226 further includes a wastegate valve 234 (the wastegate valve 234 is in Fig. removed for clarity). The wastegate valve 234 has an open configuration and a closed configuration to control fluid flow along the bypass flowpath.

[0055] The chamber inlet 230 is a passage, referred to herein as a wastegate inlet passage, formed in the turbine housing 212. The wastegate inlet passage 230 extends through the turbine housing 212 between a valve port 236, proximal to the wastegate chamber 228, and a turbine port 238, proximal to the turbine inlet 214. The turbine housing 212 includes a raised rim 252 surrounding the valve port 236. The raised rim 252 is conformally close to the valve port 236, thus the inner surface of the raised rim 252 provides an extension for the wastegate inlet passage 230. The raised rim 252 defines a sealing surface 254, which is a first sealing surface of the wastegate 226. The sealing surface 254 is defined between an outer edge 256 and an inner edge 258. The inner edge 258 corresponds to the valve connection 236.

[0056] The wastegate valve 234 includes a sealing surface 250, which is a second sealing surface of the wastegate 226. The sealing surface 250 of the valve element 242 is flat. The sealing surface 250 of the valve element 242 and the sealing surface 254 of the raised rim 252 are sealingly engageable to block fluid flow along the bypass flowpath. The sealing surface 254 of the raised rim 252 is tapered away from the valve port 236; therefore, a portion of the sealing surface 254 of the raised rim 252 is located near the inner edge 258 of the sealing surface 254, forming a seal with the sealing surface 250 of the valve element 242.Usefully, controlling the geometry of the sealing surface 254 of the raised rim 252 with a taper to provide the seal between the sealing surfaces 250, 254 near the inner edge 258 of the sealing surface 254 increases the confidence in estimating the location of the seal and therefore reduces error in estimating the effective area of ​​the valve element 242 upon which the exhaust gases exert a load, allowing the actuator to be more accurately tuned. The taper angle of the sealing surface 250 relative to a plane of the valve port 236 may be between 1° and 10°. In the present embodiment, the taper angle is 5°. In alternative embodiments, the taper angle may preferably be 2.5°.The preferred taper angle ensures that the raised rim is sufficiently robust to withstand the environment within the wastegate and any hot gases that may pass through the valve port.

[0057] The wastegate inlet passage 230 extends along an axis at an oblique angle to the plane of the valve port 236 and the plane of the turbine port 238. The wastegate inlet passage 230 has a circular cross-section when taken transversely to the axis of the passage 230. The valve port 236 is elliptical in shape because the wastegate inlet passage 230 has a circular axial cross-section and extends along an axis at an oblique angle to the plane of the valve port 236. The sealing surface 254 of the raised rim 252 has an elliptical annular shape. The outer and inner edges 256, 258 are elliptical. The sealing surface 254 of the raised rim is defined by a width between the inner and outer edges 258, 256. The width of the sealing surface 254 is constant. The width of the sealing surface 54 can be between 1 mm and 5 mm.Preferably, as in the present embodiment, the width of the sealing surface 254 is between 3 mm and 5 mm. The preferred width W of the sealing surface 254 provides an optimal width that is large enough to be sufficiently resistant to the environment within the turbine and hot gases that may pass through the wastegate, and small enough to provide an accurate sealing location so that the gas force acting on the valve element in the closed position can be accurately estimated and the wastegate actuator can be precisely tuned.

[0058] Fig. show an alternative turbine 310 provided with a wastegate 326. The turbine 310 and the wastegate 326 are substantially the same as the turbine 10 and the wastegate 26, except for the features described. Like features are designated by like reference numerals increased by 300.

[0059] The turbine 310 includes a turbine housing 312 defining a turbine inlet 314. In use, a conventional flowpath is provided through the turbine. Fluid flows into the turbine 310 via the turbine inlet 314 and impinges on a turbine wheel, causing rotation of the turbine wheel. The fluid is bypassed by the turbine wheel to flow out of the turbine 310 via a turbine outlet. To regulate the volume of fluid impinging on the turbine wheel and therefore control the rotational speed of the turbine wheel, the turbine is provided with a wastegate 326 defining a bypass flowpath and selectively diverting exhaust gas away from the turbine wheel. The wastegate 326 includes a wastegate chamber 328 having a chamber inlet 330 and a chamber outlet. The wastegate 326 further includes a wastegate valve 334.The wastegate valve 334 has an open configuration and a closed configuration to control fluid flow along the bypass flowpath.

[0060] The chamber inlet 330 is a passage, referred to herein as a wastegate inlet passage, formed in the turbine housing 312. The wastegate inlet passage 330 extends through the turbine housing 312 between a valve port 336, proximal to the wastegate chamber 328, and a turbine port 338, proximal to the turbine inlet 314. The turbine housing 312 includes a raised rim 352 surrounding the valve port 336. The raised rim 352 is conformally aligned with the valve port 336, thus the inner surface of the raised rim 352 provides an extension for the wastegate inlet passage 330. The raised rim 352 defines a sealing surface 354, which is a first sealing surface of the wastegate 326. The sealing surface 354 is defined between an outer edge 356 and an inner edge 358. The inner edge 358 corresponds to the valve connection 336.

[0061] The valve port 336 is defined by a major dimension. The wastegate inlet passage 330 extends along an axis at an oblique angle to the plane of the valve port 336 and the plane of the turbine port 338. The wastegate inlet passage 330 has a non-circular cross-section; therefore, the valve port 336 (and the inner edge 358 of the sealing surface 354) is non-circular and non-elliptical. The major dimension of the valve port 336 is a maximum distance between opposing points on the valve port 336. The outer edge 356 of the sealing surface 354 is circular. The sealing surface 354 of the raised rim is defined by a width between the inner and outer edges 358, 356. The width of the sealing surface 354 can be between 1 mm and 5 mm.Preferably, as in the present embodiment, the width of the sealing surface 354 may be between 3 mm and 5 mm. The outer edge 356 of the sealing surface 354 is defined by a larger dimension, which in the illustrated example is the diameter of the circular outer edge 356.

[0062] The valve element 342 also includes a sealing surface 350, which is a second sealing surface of the wastegate 326. The valve sealing surface 350 is defined by a minor dimension, which in the depicted example is the diameter of the circular sealing surface 350. The diameter is as large as or larger than the major dimension of the valve port. Preferably, as in the present embodiment, the diameter is also as large as or larger than the major diameter of the outer edge 356 of the sealing surface 354 defined by the raised rim 352. The sealing surface 350 of the valve element 342 is flat. The sealing surface 350 of the valve element 342 and the sealing surface 354 of the raised rim 352 can be sealingly engaged to block fluid flow along the bypass flowpath.The sealing surface 354 of the raised rim 352 is tapered away from the valve port 336; therefore, a portion of the sealing surface 354 is located near the inner edge 358 of the sealing surface 354 of the raised rim 352, which forms a seal with the sealing surface 350 of the valve element 342. The taper angle of the sealing surface 354 relative to a plane of the valve port 336 can be between 1° and 10°. In the present embodiment, the taper angle is 5°. In alternative embodiments, the taper angle can preferably be 2.5°.

[0063] Fig. show an alternative turbine 410 provided with a wastegate 426. The turbine 410 and the wastegate 426 are substantially the same as the turbine 10 and the wastegate 26, except for the features described. Like features are designated by like reference numerals increased by 400.

[0064] The turbine 410 includes a turbine housing 412 defining a turbine inlet 414. In use, a conventional flowpath is provided through the turbine. Fluid flows into the turbine 410 via the turbine inlet 414 and impinges on a turbine wheel, causing rotation of the turbine wheel. The fluid is bypassed by the turbine wheel to flow out of the turbine 410 via a turbine outlet. To regulate the volume of fluid impinging on the turbine wheel and therefore control the rotational speed of the turbine wheel, the turbine is provided with a wastegate 426 defining a bypass flowpath and selectively diverting exhaust gas away from the turbine wheel. The wastegate 426 includes a wastegate chamber 428 having a chamber inlet 430 and a chamber outlet. The wastegate 426 further includes a wastegate valve 434.The wastegate valve 434 has an open configuration and a closed configuration to control fluid flow along the bypass flowpath.

[0065] The chamber inlet 430 is a passage, referred to herein as a wastegate inlet passage, formed in the turbine housing 412. The wastegate inlet passage 430 extends through the turbine housing 412 between a valve port 436, proximal to the wastegate chamber 428, and a turbine port 438, proximal to the turbine inlet 414. The turbine housing 412 includes a raised rim 452 surrounding the valve port 436. The raised rim 452 is conformally close to the valve port 436, thus the inner surface of the raised rim 452 provides an extension for the wastegate inlet passage 430. The raised rim 452 defines a sealing surface 454, which is a first sealing surface of the wastegate 426. The sealing surface 454 is defined between an outer edge 456 and an inner edge 458. The inner edge 458 corresponds to the valve connection 436.

[0066] The valve port 436 is defined by a major dimension. The wastegate inlet passage 430 extends along an axis at an oblique angle to the plane of the valve port 436 and the plane of the turbine port 438. The wastegate inlet passage 430 has a non-circular cross-section; therefore, the valve port 436 is non-circular and non-elliptical. The major dimension of the valve port 436 is a maximum distance between opposing points on the valve port 436.

[0067] The sealing surface 454 of the raised rim is defined by a width between the inner and outer edges 458, 456. The width of the sealing surface 454 is constant. The outer edge 456 of the sealing surface 454 is defined by a larger dimension, which is a maximum distance between opposing points on the sealing surface 454. Since the width of the sealing surface 454 is constant, the larger dimension of the sealing surface 454 is the larger dimension of the valve port 436 plus two widths.

[0068] The valve element 442 also includes a sealing surface 450, which is a second sealing surface of the wastegate 426. The valve sealing surface 450 is defined by a minor dimension, which in the depicted example is the diameter of the circular sealing surface. The diameter is as large as or larger than the major dimension of the valve port 436. Preferably, as in the present embodiment, the diameter is also as large as or larger than the major dimension of the outer edge 456 of the sealing surface 454, which is defined by the raised rim 452.

[0069] The sealing surface 454 of the raised rim 452 is rounded. In particular, the sealing surface 454 of the raised rim 452 is concave. The concave sealing surface 450 has a radius of 6 mm. The sealing surface 450 of the valve element 442 and the sealing surface 454 of the raised rim 452 can be sealingly engaged to block fluid flow along the bypass flowpath. The inner edge 458 of the sealing surface 450 of the raised rim 452 is closer to the valve element than the outer edge 456; therefore, it is the inner edge 458 of the sealing surface 454 of the raised rim 452 that forms a seal with the sealing surface 450 of the valve element 442. Usefully, controlling the geometry of the sealing surface 454 in this manner increases the confidence in estimating the sealing location and therefore reduces error in estimating the effective area of ​​the valve element 442 on which the exhaust gases exert a load.The reduced estimation error allows the actuator to be tuned more precisely.

[0070] The above description is intended to be exemplary only and not limiting. It should be understood that features defined above may be used in accordance with any aspect of the present disclosure or any specific embodiment of the disclosure, either alone or in combination with any other defined feature, in any other aspect or embodiment, or to form a further aspect or embodiment of the disclosure. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 2489853A1

[0008]

Claims

A turbine comprising: a wastegate chamber, a turbine housing defining a turbine inlet, the turbine housing comprising: a wastegate inlet passage defining a flow path between the turbine inlet and the wastegate chamber, the wastegate inlet passage comprising a turbine port proximal to the turbine inlet and a non-circular valve port proximal to the wastegate chamber, and a raised rim surrounding the non-circular valve port and conforming closely to the shape of the non-circular valve port, the raised rim comprising a first sealing surface, and a valve element comprising a second sealing surface, the valve element being movable between a closed position in which the second sealing surface forms a seal with the first sealing surface to prevent fluid flow along the flow path, and an open position,in which the second sealing surface is spaced from the first sealing surface to allow fluid flow along the flow path., A turbine according to any one of the preceding claims, wherein the non-circular valve port defines a plane, and wherein the wastegate inlet passage extends along a passage axis at an oblique angle to the plane of the non-circular valve port. The turbine of claim 1 or 2, wherein the non-circular valve port has a major dimension defined by a maximum distance between opposing points on the valve port, the second sealing surface has a minor dimension defined by a minimum distance between opposing points on an outer edge of the second sealing surface, and the minor dimension of the second sealing surface is greater than the major dimension of the non-circular valve port. A turbine according to claim 3, wherein the second sealing surface defines a valve axis through its center, and wherein the valve element can rotate freely about the valve axis. A turbine according to claim 3 or 4, wherein the non-circular valve port is elliptical and wherein the elliptical valve port is defined by a major diameter and a minor diameter, and wherein the major dimension of the elliptical valve port is its major diameter. Turbine according to claim 5, wherein the first sealing surface has the shape of an elliptical ring. Turbine according to one of the preceding claims, wherein the first sealing surface has a constant width. Turbine according to claim 7, wherein the first sealing surface has a width of 5 mm or less. Turbine according to one of claims 3 to 8, wherein the second sealing surface is circular, and wherein the smaller dimension of the second sealing surface is the diameter of the second sealing surface. Turbine according to one of claims 3 to 9, wherein the first sealing surface has a major dimension defined by a maximum distance between opposing points on an outer edge of the first sealing surface, and wherein the minor dimension of the second sealing surface is greater than the major dimension of the first sealing surface. A turbine according to claim 10 when dependent on at least claim 6, wherein the elliptical outer edge of the first sealing surface is defined by a major diameter and a minor diameter, and wherein the major dimension of the elliptical outer edge of the first sealing surface is its major diameter. Turbine according to one of the preceding claims, wherein the raised rim and / or the wastegate inlet passage in the turbine housing are formed by interpolation milling. Turbine according to one of the preceding claims, wherein the first sealing surface and the valve port are coplanar. A turbine according to any one of claims 1 to 12, wherein the first sealing surface is tapered away from the valve port, and wherein in the closed position the second sealing surface forms a seal with an inner edge of the first sealing surface. A turbocharger comprising a turbine according to any one of the preceding claims. A method of manufacturing a turbine according to claim 1, wherein the method comprises forming the raised edge by interpolation milling.

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