Turbine and supercharger

Abstract

To provide a turbine which can improve a robust property, and a supercharger having the turbine.SOLUTION: A turbine comprises: a turbine impeller; an exhaust gas flow passage forming part which forms an exhaust gas flow passage for introducing an exhaust gas to the turbine impeller from a scroll flow passage which is formed at an external peripheral side of the turbine impeller, the exhaust gas flow passage forming part including a hub-side flow passage face and a shroud-side flow passage face for defining the exhaust gas flow passage; and at least one nozzle vane arranged in the exhaust gas flow passage, and fixed to at least either of the hub-side flow passage face or the shroud-side flow passage face. A blade height W1 being a length of the turbine impeller of at least one nozzle vane in an axial direction is lower than a flow passage width W0 being a length of the exhaust gas flow passage in a blade front edge position of the turbine impeller in the axial direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a turbine and a supercharger including the turbine.

Background Art

[0002] Some supercharger turbines include turbine blades and a plurality of nozzle blades provided upstream of the turbine blades in the exhaust gas flow path of the engine. The plurality of nozzle blades are arranged outside the turbine blades in the radial direction. The turbine is configured to improve the energy recovery efficiency by expanding and accelerating the exhaust gas in which the nozzle blades are guided to the turbine blades (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The exhaust gas flowing through the exhaust gas flow path of the engine may contain vaporized fuel, lubricating oil, etc. Carbon (dust) is likely to accumulate on the parts exposed to the exhaust gas such as the nozzle blades. When carbon accumulates on the blade surface of the nozzle blade, the throat area of the nozzle blade becomes small, so there is a risk of causing surging. As a countermeasure against carbon deposition, early maintenance and cleaning of the nozzle blades are required, so there is a problem that continuous operation of the supercharger or the engine equipped with the supercharger becomes difficult. For this reason, improvement in the robustness of the turbine (specifically, the nozzle blades) against carbon deposition is required.

[0005] In view of the above circumstances, at least one embodiment of the present invention aims to provide a turbine capable of improving robustness and a supercharger including the turbine.

Means for Solving the Problems

[0006] The turbine according to at least one embodiment of the present invention is a turbine impeller, an exhaust gas flow path forming portion that forms an exhaust gas flow path for guiding exhaust gas from a scroll flow path formed on the outer peripheral side of the turbine impeller to the turbine impeller, the exhaust gas flow path forming portion including a hub side flow path surface and a shroud side flow path surface that define the exhaust gas flow path, and at least one nozzle vane disposed in the exhaust gas flow path and fixed to at least one of the hub side flow path surface or the shroud side flow path surface. The blade height W1, which is the length in the axial direction of the turbine impeller of the at least one nozzle vane, is smaller than the flow path width W0, which is the length in the axial direction of the exhaust gas flow path at the leading edge position of the blade of the turbine impeller.

[0007] The supercharger according to at least one embodiment of the present invention is the turbine, and a centrifugal compressor configured to be driven by the turbine.

Advantages of the Invention

[0008] According to at least one embodiment of the present invention, there is provided a turbine capable of improving robustness, and a supercharger including the turbine.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0010] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.

[0011] (Basic Configuration of Turbine) FIG. 1 is a schematic cross-sectional view showing a cross-section along the axis of the turbine according to one embodiment. As shown in FIG. 1, a turbine 1 according to some embodiments includes a turbine impeller (hereinafter referred to as an impeller) 2 and a casing 3 configured to rotatably accommodate the impeller 2. The turbine 1 according to the present disclosure can be mounted on, for example, a supercharger 10 for automobiles, ships, or industries (for example, onshore power generation).

[0012] The impeller 2 is supported by a bearing (not shown) housed inside the casing 3, and is configured to be rotatable about the axis LA of the impeller 2. Hereinafter, the direction in which the axis LA of the impeller 2 extends is defined as the axial direction of the impeller 2 (turbine 1), and the direction orthogonal to the axis LA is defined as the radial direction of the impeller 2 (turbine 1). The impeller 2 is configured to guide the exhaust gas introduced from the outside in the radial direction of the impeller 2 along the axial direction of the impeller 2 to the outlet side (the right side in FIG. 1) of the turbine 1.

[0013] Hereinafter, the outlet side of the turbine 1 in the above axial direction is referred to as the shroud side, and the side opposite to the shroud side is referred to as the hub side. In the following description, when simply referred to as the upstream side, it refers to the upstream side along the main flow direction of the fluid in the part or region related to the direction description. Similarly, in the following description, when simply referred to as the downstream side, it refers to the downstream side along the main flow direction of the fluid in the part or region related to the direction description.

[0014] The impeller 2 includes a hub 21 and a plurality of impeller blades 23 erected on the outer surface 22 of the hub 21. Each of the plurality of impeller blades 23 is arranged at intervals in the circumferential direction of the impeller 2. The tip 24 of each of the plurality of impeller blades 23 is arranged with a predetermined gap with respect to the shroud surface 31 which is the inner surface of the casing 3.

[0015] (Casing) As shown in FIG. 1, the casing 3 includes a shroud portion 32 having the above-described shroud surface 31, a scroll flow path forming portion 34 that forms a scroll flow path 33 on the outer peripheral side of the impeller 2, and an exhaust gas flow path forming portion 36 that forms an exhaust gas flow path 35 for guiding exhaust gas from the scroll flow path 33 to the impeller 2. Each of the scroll flow path 33 and the exhaust gas flow path 35 is formed inside the casing 3.

[0016] The scroll flow path 33 is a spiral flow path provided on the outer peripheral side of the impeller 2. This spiral flow path extends along the circumferential direction of the impeller 2 so as to surround the outer peripheral side (the outer side in the radial direction) of the impeller 2. The exhaust gas flow path 35 is provided between the scroll flow path 33 and the impeller 2 in the radial direction of the impeller 2 so as to surround the outer peripheral side (the outer side in the radial direction) of the impeller 2.

[0017] In the illustrated embodiment, the exhaust gas flow path 35 is formed in an annular shape extending along the circumferential direction of the impeller 2, and the upstream end (outer peripheral end) of the exhaust gas flow path 35 communicates with the scroll flow path 33. The exhaust gas flow path 35 extends along the radial direction of the impeller 2 in a cross section along the axial direction of the impeller 2 as shown in FIG. 1. The exhaust gas introduced into the casing 3 passes through the scroll flow path 33, and then after passing through the exhaust gas flow path 35, it is guided to the impeller 2 to rotate the impeller 2.

[0018] The exhaust gas flow path forming portion 36 includes a hub side flow path surface 4 and a shroud side flow path surface 5 that define the exhaust gas flow path 35. The shroud side flow path surface 5 is provided on the shroud side of the hub side flow path surface 4 and faces the hub side flow path surface 4 across the exhaust gas flow path 35. The hub side flow path surface 4 defines the hub side (the left side in FIG. 1) of the exhaust gas flow path 35, and the shroud side flow path surface 5 defines the shroud side (the right side in FIG. 1) of the exhaust gas flow path 35. In the illustrated embodiment, each of the hub side flow path surface 4 and the shroud side flow path surface 5 is formed in an annular shape extending along the circumferential direction of the impeller 2 on the outer peripheral side of the impeller 2.

[0019] (Nozzle vane) FIG. 2 is a schematic cross-sectional view showing a cross section along an axis on one side of the axis of the turbine according to an embodiment. FIG. 3 is a schematic view showing a state of viewing the hub side flow path surface and a plurality of nozzle vanes of the turbine according to an embodiment from the shroud side. As described above, the turbine 1 further includes at least one nozzle vane 6 disposed in the exhaust gas flow path 35 and fixed to at least one of the hub-side flow surface 4 or the shroud-side flow surface 5, as shown in FIGS. 2 and 3. In the illustrated embodiment, the at least one nozzle vane 6 described above includes a plurality of nozzle vanes 6 spaced apart from each other in the circumferential direction of the impeller 2.

[0020] In the illustrated embodiment, the exhaust gas flow path forming portion 36 includes an annular member 40 having a hub-side flow surface 4. Each of the plurality of nozzle vanes 6 is integrally formed with the annular member 40, and the end surface on the hub side in the axial direction thereof is connected to the hub-side flow surface 4. Thereby, each of the plurality of nozzle vanes 6 is fixed to the hub-side flow surface 4.

[0021] As shown in FIG. 3, each of the plurality of nozzle vanes 6 includes a leading edge 61 provided at one end in the extending direction of the vane thickness center line CL passing through the vane thickness center of the nozzle vane 6, and a trailing edge 62 provided at the other end in the extending direction of the vane thickness center line CL of the nozzle vane 6, and an inner vane surface 63 and an outer vane surface 64 each extending from the leading edge 61 to the trailing edge 62. In each of the plurality of nozzle vanes 6, the trailing edge 62 is provided on the inner side in the radial direction of the impeller 2 than the leading edge 61. In each of the plurality of nozzle vanes 6, the inner vane surface 63 is provided on the opposite side of the outer vane surface 64 with the vane thickness center line CL interposed therebetween, and on the inner side in the radial direction than the outer vane surface 64. The leading edge 61, the trailing edge 62, the inner vane surface 63, and the outer vane surface 64 of the nozzle vane 6 constitute a vane surface facing the exhaust gas flow path 35.

[0022] (Throat) As shown in FIG. 3, the position where the flow path area between a pair of nozzle vanes 6, 6 adjacent to each other along the circumferential direction of the impeller 2 is minimized is defined as the throat T. The flow path area between the pair of nozzle vanes 6, 6 at the throat T is defined as the nozzle throat area, the length in the axial direction of the exhaust gas flow path 35 at the throat T is defined as the nozzle throat height, and the length between the pair of nozzle vanes 6, 6 at the throat T is defined as the nozzle throat width.

[0023] (Relationship between vane height W1 and flow path width W0) As shown in FIG. 2, the turbine 1 according to some embodiments includes an exhaust gas flow path forming portion 36 including the above-described hub side flow path surface 4 and shroud side flow path surface 5, and the above-described at least one nozzle vane 6. The vane height W1, which is the length in the axial direction of the impeller 2 of the at least one nozzle vane 6, is smaller than the flow path width W0, which is the length in the axial direction of the exhaust gas flow path 35 at the vane leading edge position of the impeller 2. The vane leading edge position of the impeller 2 is the position where the leading edge 25 of the impeller 2 is disposed on the casing 3 when the impeller 2 is disposed inside the casing 3.

[0024] In the embodiment shown in FIGS. 2 and 3, the hub side flow path surface 4 has a step 42 that protrudes toward the shroud side from the hub side end 26 of the leading edge 25 of the impeller 2. As a result, the vane height W1 of each of the plurality of nozzle vanes 6 is smaller than the flow path width W0. Instead of providing the step 42 on the hub side flow path surface 4, the vane height W1 may be made smaller than the flow path width W0 by providing a step that protrudes toward the hub side on the shroud side flow path surface 5.

[0025] (Turbine according to comparative example) FIG. 4 is a schematic cross-sectional view showing a cross-section along an axis on one side with respect to the axis of the turbine according to the comparative example. FIG. 5 is a schematic view showing a state in which the hub side flow path surface and the plurality of nozzle vanes of the turbine according to the comparative example are viewed from the shroud side. As shown in FIGS. 4 and 5, the turbine 1A according to the comparative example does not have a step protruding from the hub side flow path surface 4A of the annular member 40A toward the shroud side or a step protruding from the shroud side flow path surface 5 toward the hub side. The hub side flow path surface 4A is provided at the same position as the hub side end 26 of the leading edge 25 of the impeller 2 in the axial direction of the impeller 2. The vane height W2, which is the length in the axial direction of the impeller 2 of each of the plurality of nozzle vanes 6A, is the same as the flow path width W0, which is the length in the axial direction of the exhaust gas flow path 35 at the vane leading edge position of the impeller 2. The vane height W1 of each of the plurality of nozzle vanes 6 in the present embodiment is smaller than the vane height W2 of each of the plurality of nozzle vanes 6A.

[0026] (Carbon deposition amount according to nozzle throat shape) FIG. 6 is an explanatory diagram for explaining the carbon deposition amount according to the nozzle throat shape of the turbine. In FIG. 6, the nozzle throat height (vane height of the nozzle vane 6) TH of the turbine 1 according to the present embodiment is smaller than the nozzle throat height (vane height of the nozzle vane 6A) TH1 of the turbine 1A according to the comparative example. In FIG. 6, the nozzle throat width TW of the turbine 1 is made larger than the nozzle throat width TW1 of the turbine 1A, so that the nozzle throat areas TA of the turbine 1 and the turbine 1A are the same. As shown in FIG. 6, the larger the nozzle throat height (vane height of the nozzle vane), the larger the areas of the vane surfaces (inner vane surfaces 63, 63A, outer vane surfaces 64, 64A, etc.) of the nozzle vanes 6 and 6A, and the larger the carbon deposition amount adhering to the vane surface of the nozzle vane 6. Note that the hub-side flow path surface 4 and the shroud-side flow path surface 5 tend to have less carbon deposition amount than the vane surface of the nozzle vane 6.

[0027] (Change in effective nozzle throat area) FIG. 7 is an explanatory diagram for explaining the change in the effective nozzle throat area due to carbon deposition in a turbine according to an embodiment. In FIG. 7, a graph is shown with the operating period WT of the turbine on the horizontal axis and the effective nozzle throat area ETA obtained by subtracting the above-mentioned closing area from the nozzle throat area TA on the vertical axis. SL in FIG. 7 is the surging limit. When the effective nozzle throat area ETA becomes equal to or less than the surging limit SL, surging is likely to occur. L1 in FIG. 7 is an approximate straight line showing the change in the effective nozzle throat area ETA corresponding to the operating period WT of the turbine 1A shown in FIG. 6, and the effective nozzle throat area ETA reaches the surging limit SL during the period WT1. L2 in FIG. 7 is an approximate straight line showing the change in the effective nozzle throat area ETA corresponding to the operating period WT of the turbine 1 shown in FIG. 6, and the effective nozzle throat area ETA reaches the surging limit SL during the period WT2. As shown in FIG. 7, the period WT2 is larger than the period WT1. That is, the turbine 1 can have a longer operating period until it reaches the surging limit SL than the turbine 1A.

[0028] In the present embodiment, by making the blade height W1 of at least one nozzle vane 6 smaller than the channel width W0 of the exhaust gas channel 35 at the leading edge position of the impeller 2, the area of the blade surface of the nozzle vane 6 becomes smaller compared to the case where the blade height W1 has the same length as the channel width W0, so the amount of carbon deposition can be reduced. As a result, the area (closing area) where the carbon attached to the blade surface of the nozzle vane 6 closes the nozzle throat area TA can be reduced. By reducing the closing area, the maintenance frequency of the turbine 1 can be reduced, and the operating time of the turbine 1 and the supercharger 10 including the turbine 1 can be extended. According to such a turbine 1, since the adverse effect due to the carbon deposition on the nozzle throat area TA can be reduced, the robustness of the turbine 1 can be improved.

[0029] In some embodiments, for each of the plurality of nozzle vanes 6 described above, the distance D1 (see FIG. 3) from the axis LA of the impeller 2 to the trailing edge 62 of the nozzle vane 6 is determined so as to obtain a desired nozzle throat width TW.

[0030] According to the above configuration, simply making the blade height W1 smaller than the channel width W0 will result in a smaller nozzle throat area compared to the case where the blade height W1 is the same length as the channel width W0. When the blade height W1 is made smaller than the channel width W0, in order to ensure the same nozzle throat area TA as in the case where the blade height W1 is the same length as the channel width W0, it is necessary to make the nozzle throat width TW longer than in the case where the blade height W1 is the same length as the channel width W0 (see Fig. 6).

[0031] The distance D1 from the axis LA of the impeller 2 of the turbine 1 shown in Fig. 3 to the trailing edge 62 of the nozzle vane 6 is greater than the distance D2 from the axis LA of the impeller 2 of the turbine 1A shown in Fig. 5 to the trailing edge 62A of the nozzle vane 6A. Thus, when the blade height W1 is made smaller than the channel width W0, by making the distance D1 from the axis LA of the impeller 2 to the trailing edge 62 of the nozzle vane 6 greater than in the case where the blade height W1 is the same length as the channel width W0, the nozzle throat width TW can be widened. By adjusting the distance D1 from the axis LA of the impeller 2 to the trailing edge 62 of each of the plurality of nozzle vanes 6, a desired nozzle throat width TW and a desired nozzle throat area TA can be ensured, and thus the performance of the turbine 1 and the supercharger 10 equipped with the turbine 1 can also be ensured.

[0032] In some embodiments, for each of the plurality of nozzle vanes 6 described above, when the angle between the tangent TL1 at the trailing edge 62 of the virtual circle VC passing through the trailing edge 62 of the nozzle vane 6 centered on the axis LA of the impeller 2 and the tangent TL2 at the trailing edge 62 of the blade surface (inner blade surface 63) on the impeller 2 side of the nozzle vane 6 is defined as the setting angle θ, the setting angle θ is determined so as to obtain the desired nozzle throat width TW.

[0033] According to the above configuration, simply making the blade height W1 smaller than the channel width W0 reduces the nozzle throat area compared to the case where the blade height W1 is the same length as the channel width W0. When the blade height W1 is made smaller than the channel width W0, in order to ensure the same nozzle throat area TA as in the case where the blade height W1 is the same length as the channel width W0, it is necessary to make the nozzle throat width TW longer than in the case where the blade height W1 is the same length as the channel width W0 (see Fig. 6).

[0034] As shown in Fig. 5, an angle corresponding to the above-mentioned setting angle θ of the turbine 1A according to the comparative example is defined as the setting angle θ1. The setting angle θ1 is the angle formed by the tangent at the trailing edge 62A of the virtual circle VC and the tangent at the trailing edge 62A of the inner blade surface 63A of the nozzle vane 6A. The setting angle θ of the turbine 1 shown in Fig. 3 is larger than the setting angle θ1 of the turbine 1A shown in Fig. 5. Thus, when the blade height W1 is made smaller than the channel width W0, by making the setting angle θ larger than in the case where the blade height W1 is the same length as the channel width W0, the nozzle throat width TW can be widened. By adjusting the setting angle θ for each of the plurality of nozzle vanes 6, a desired nozzle throat width TW and a desired nozzle throat area TA can be ensured, and thus the performance of the turbine 1 and the supercharger 10 including the turbine 1 can also be ensured.

[0035] (Step) In some embodiments, as shown in Figs. 2 and 3, the above-mentioned hub-side flow path surface 4 includes a flat surface 41 formed in a region sandwiching at least one nozzle vane 6 between the shroud-side flow path surface 5. The flat surface 41 is located on the shroud side of the hub-side end 26 of the leading edge 25 of the impeller 2 in the axial direction of the impeller 2 and extends along the radial direction of the impeller 2. In the illustrated embodiment, the flat surface 41 is formed of an annular surface extending along the circumferential direction of the impeller 2.

[0036] According to the above configuration, by providing a step 42 on the hub-side flow path surface 4 with a flat surface 41 that protrudes toward the shroud side from the hub-side end 26 of the leading edge 25 of the impeller 2 as the top surface, the blade height W1 can be made smaller than the flow path width W0. By providing the step 42 on the hub-side flow path surface 4, compared with the case where the step 42 is provided on the shroud-side flow path surface 5, the flow path loss in the exhaust gas flow path 35 can be reduced, and the performance degradation of the turbine 1 can be suppressed.

[0037] (Inner inclined surface of the step) In some embodiments, as shown in FIGS. 2 and 3, the above-described hub-side flow path surface 4 further includes an inner inclined surface 43 that inclines toward the hub side as it goes toward the inner side in the radial direction of the impeller 2 with respect to the flat surface 41.

[0038] In the illustrated embodiment, the inner inclined surface 43 is formed of an annular surface extending along the circumferential direction of the impeller 2. The outer peripheral edge of the inner inclined surface 43 is continuous with the inner peripheral edge of the flat surface 41. Further, the inner peripheral edge of the inner inclined surface 43 constitutes the inner peripheral edge of the hub-side flow path surface 4 of the annular member 40. It is preferable that the length (flow path width) in the axial direction of the exhaust gas flow path 35 at the position of the inner peripheral edge of the inner inclined surface 43 is the same as the flow path width W0.

[0039] According to the above configuration, since the step 42 provided on the hub-side flow path surface 4 includes the inner inclined surface 43, the flow path cross-sectional area of the exhaust gas flow path 35 can be gradually increased on the downstream side (inner side in the radial direction) of at least one nozzle vane 6 of the exhaust gas flow path 35. As a result, a part of the exhaust gas flowing through the exhaust gas flow path 35 can be guided along the inner inclined surface 43 to the hub side of the leading edge 25 of the impeller 2, so that the performance degradation of the turbine 1 due to the step 42 can be suppressed. If the step 42 does not include the inner inclined surface 43, in the axial region of the leading edge 25 of the impeller 2, a region where no exhaust gas is supplied may occur, and the effective area of the impeller 2 may decrease. Further, if the step 42 does not include the inner inclined surface 43, there is a possibility that vortices and separations of the exhaust gas flow may occur on the downstream side of the step 42 in the flow direction of the exhaust gas.

[0040] (Outer inclined surface of the step) In some embodiments, as shown in FIGS. 2 and 3, the hub-side flow path surface 4 described above further includes an outer inclined surface 44 that is inclined toward the hub in the radial direction outside the impeller 2 rather than the flat surface 41. In the illustrated embodiment, the outer inclined surface 44 is formed of an annular surface extending along the circumferential direction of the impeller 2.

[0041] In the illustrated embodiment, the outer inclined surface 44 is formed of an annular surface extending along the circumferential direction of the impeller 2. The inner peripheral edge of the outer inclined surface 44 is continuous with the outer peripheral edge of the flat surface 41. Further, the outer peripheral edge of the outer inclined surface 44 constitutes the outer peripheral edge of the hub-side flow path surface 4 of the annular member 40. Note that the axial length (flow path width) of the exhaust gas flow path 35 at the position of the outer peripheral edge of the outer inclined surface 44 may be the same length as the flow path width W0.

[0042] According to the above configuration, since the step 42 provided on the hub-side flow path surface 4 includes the outer inclined surface 44, the flow path cross-sectional area of the exhaust gas flow path 35 can be gradually reduced upstream (outside in the radial direction) of at least one nozzle vane 6 of the exhaust gas flow path 35. Thereby, the flow path loss in the exhaust gas flow path 35 due to the step 42 can be reduced, and thus the performance degradation of the turbine 1 due to the step 42 can be suppressed.

[0043] (Inclination angles of the outer inclined surface and the inner inclined surface) In some embodiments, as shown in FIG. 2, the hub-side flow path surface 4 described above is configured such that the inclination angle α of the outer inclined surface 44 is smaller than the inclination angle β of the inner inclined surface 43. The inclination angle α of the outer inclined surface 44 is an angle formed by the virtual extension surface VL extending the flat surface 41 and the outer inclined surface 44. The inclination angle β of the inner inclined surface 43 is an angle formed by the virtual extension surface VL and the inner inclined surface 43.

[0044] According to the above configuration, by making the inclination angle α of the outer inclined surface 44 smaller than the inclination angle β of the inner inclined surface 43, the flow path cross-sectional area of the exhaust gas flow path 35 can be gently decreased on the upstream side (the outer side in the radial direction) of at least one nozzle vane 6 of the exhaust gas flow path 35. Thereby, the flow path loss in the exhaust gas flow path 35 due to the step 42 can be effectively reduced.

[0045] (Supercharger) FIG. 8 is a schematic view of a supercharger according to an embodiment. The supercharger 10 according to some embodiments includes the turbine 1 with improved robustness described above and a centrifugal compressor 11 configured to be driven by the turbine 1. The centrifugal compressor 11 includes a compressor impeller 12, and the supercharger 10 further includes a rotating shaft 13 to which the impeller 2 is connected at one end side and the compressor impeller 12 is connected at the other end side. The impeller 2 is rotationally driven by the exhaust gas from the engine 14. The compressor impeller 12 is rotationally driven in conjunction with the rotational drive of the impeller 2 and compresses the fluid (for example, air, etc.) sent to the engine 14.

[0046] Some embodiments of the present disclosure are also applicable to a method for modifying a turbine in which the turbine 1A according to the comparative example is modified to the turbine 1. By removing the annular member 40A to which a plurality of nozzle vanes 6A are fixed from the casing 3 of the turbine 1A and newly attaching the annular member 40 to which the plurality of nozzle vanes 6 are fixed to the casing 3, the turbine 1A can be modified to the turbine 1.

[0047] In this specification, expressions representing relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" not only strictly represent such arrangements, but also represent a state of being relatively displaced with tolerances, or at an angle or distance such that the same function can be obtained. For example, expressions representing that things such as "identical", "equal", and "homogeneous" are in an equal state not only strictly represent an equal state, but also represent a state in which there are tolerances or differences such that the same function can be obtained. In addition, in this specification, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in a geometrically strict sense, but also represent shapes including concave and convex portions, chamfered portions, etc. within a range where the same effect can be obtained. In addition, in this specification, the expressions “comprises,” “includes,” or “has” for one component are not exclusive expressions that exclude the existence of other components.

[0048] The present disclosure is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.

[0049] The content described in some of the above-described embodiments is understood as follows, for example.

[0050] 1) The turbine (1) according to at least one embodiment of the present disclosure is a turbine impeller (2), an exhaust gas passage forming portion (36) that forms an exhaust gas passage (35) for guiding exhaust gas from a scroll passage (33) formed on the outer peripheral side of the turbine impeller (2) to the turbine impeller (2), the exhaust gas passage forming portion (36) including a hub side flow surface (4) and a shroud side flow surface (5) that define the exhaust gas passage (35), and at least one nozzle vane (6) disposed in the exhaust gas passage (35) and fixed to at least one of the hub side flow surface (4) or the shroud side flow surface (5), wherein a vane height W1, which is the length of the at least one nozzle vane (6) in the axial direction of the turbine impeller (2), is smaller than a flow path width W0, which is the length of the exhaust gas passage (35) in the axial direction at the vane leading edge position of the turbine impeller (2).

[0051] According to the configuration of 1) above, by making the blade height W1 of at least one nozzle vane smaller than the channel width W0 of the exhaust gas channel (35) at the leading edge position of the turbine impeller (2), the area of the blade surface of the nozzle vane (6) becomes smaller compared to the case where the blade height W1 is the same length as the channel width W0. Therefore, the amount of carbon deposition can be reduced. As a result, the area (blocking area) where the carbon attached to the blade surface of the nozzle vane (6) blocks the nozzle throat area can be reduced. By reducing the blocking area, the maintenance frequency of the turbine (1) can be decreased, and the operating time of the turbine (1) and the supercharger (10) equipped with the turbine (1) can be extended. According to such a turbine (1), since the adverse effect caused by the carbon deposition on the nozzle throat area can be reduced, the robustness of the turbine (1) can be improved.

[0052] 2) In some embodiments, the turbine (1) described in 1) above, the at least one nozzle vane (6) includes a plurality of nozzle vanes (6) arranged at intervals in the circumferential direction of the turbine impeller (2), for each of the plurality of nozzle vanes (6), the distance (D1) from the axis (LA) of the turbine impeller (2) to the trailing edge (62) of the nozzle vane (6) is determined so as to obtain a desired nozzle throat width.

[0053] According to the configuration of 2) above, simply making the blade height W1 smaller than the channel width W0 will result in a smaller nozzle throat area compared to the case where the blade height W1 is the same length as the channel width W0. When the blade height W1 is made smaller than the channel width W0, in order to ensure the same nozzle throat area as in the case where the blade height W1 is the same length as the channel width W0, it is necessary to make the nozzle throat width longer than in the case where the blade height W1 is the same length as the channel width W0. When the blade height W1 is made smaller than the channel width W0, by increasing the distance (D1) from the axis (LA) of the turbine impeller (2) to the trailing edge (62) of the nozzle vane (6) compared to the case where the blade height W1 is the same length as the channel width W0, the nozzle throat width can be widened. By adjusting the distance (D1) from the axis (LA) of the turbine impeller (2) to the trailing edge (62) of each of the plurality of nozzle vanes (6), a desired nozzle throat width and a desired nozzle throat area can be ensured, and thus the performance of the turbine (1) and the supercharger (10) equipped with the turbine (1) can also be ensured.

[0054] 3) In some embodiments, the turbine (1) described in 1) or 2) above, the at least one nozzle vane (6) includes a plurality of nozzle vanes (6) spaced apart from each other in the circumferential direction of the turbine impeller (2), when an angle θ is defined as the angle formed by a tangent line (TL1) at the trailing edge (62) of a virtual circle (VC) passing through the trailing edge (62) of the nozzle vane (6) centered on the axis (LA) of the turbine impeller (2) and a tangent line (TL2) at the trailing edge (62) of the blade surface (inner blade surface 63) on the turbine impeller (2) side of the nozzle vane (6), the setting angle θ is determined so as to obtain a desired nozzle throat width.

[0055] According to the configuration of 3) above, when the blade height W1 is made smaller than the channel width W0, by increasing the placement angle θ compared to the case where the blade height W1 is the same length as the channel width W0, the nozzle throat width can be widened. For each of the plurality of nozzle vanes (6), by adjusting the placement angle θ, a desired nozzle throat width and a desired nozzle throat area can be ensured, and thus the performance of the turbine (1) or the supercharger (10) provided with the turbine (1) can also be ensured.

[0056] 4) In some embodiments, the turbine (1) described in any one of 1) to 3) above, The hub-side flow path surface (4) is a flat surface (41) formed in a region sandwiching the at least one nozzle vane (6) between the hub-side flow path surface (4) and the shroud-side flow path surface (5), and is located on the shroud side of the hub-side end (26) of the leading edge (25) of the turbine impeller (2) in the axial direction and includes a flat surface (41) extending along the radial direction of the turbine impeller (2).

[0057] According to the configuration of 4) above, by providing a step (42) having a flat surface (41) protruding on the shroud side of the hub-side end (26) of the leading edge (25) of the turbine impeller (2) on the hub-side flow path surface (4), the blade height W1 can be made smaller than the channel width W0. By providing the step (42) on the hub-side flow path surface (4), compared with the case where the step (42) is provided on the shroud-side flow path surface (5), the flow path loss in the exhaust gas flow path (35) can be reduced, and the performance degradation of the turbine (1) can be suppressed.

[0058] 5) In some embodiments, the turbine (1) described in 4) above, The hub-side flow path surface (4) further includes an inner inclined surface (43) that inclines toward the hub side as it goes inward in the radial direction of the turbine impeller (2) relative to the flat surface (41).

[0059] According to the configuration of 5) above, since the step (42) provided on the hub-side flow path surface (4) includes the inner inclined surface (43), the flow path cross-sectional area of the exhaust gas flow path (35) can be gradually increased on the downstream side of at least one nozzle vane (6) of the exhaust gas flow path (35). As a result, a part of the exhaust gas flowing through the exhaust gas flow path (35) can be guided along the inner inclined surface (43) to the hub side of the leading edge (25) of the turbine impeller (2), so that the performance degradation of the turbine (1) due to the step (42) can be suppressed.

[0060] 6) In some embodiments, the turbine (1) described in 4) or 5) above, The hub-side flow path surface (4) further includes an outer inclined surface (44) that is inclined toward the hub on the outer side in the radial direction of the turbine impeller (2) with respect to the flat surface (41).

[0061] According to the configuration of 6) above, since the step (42) provided on the hub-side flow path surface (4) includes the outer inclined surface (44), the flow path cross-sectional area of the exhaust gas flow path (35) can be gradually decreased on the upstream side of at least one nozzle vane (6) of the exhaust gas flow path (35). As a result, the flow path loss in the exhaust gas flow path (35) due to the step (42) can be reduced, so that the performance degradation of the turbine (1) due to the step (42) can be suppressed.

[0062] 7) The supercharger (10) according to at least one embodiment of the present disclosure includes the turbine (1) described in any one of 1) to 6) above, and a centrifugal compressor (11) configured to be driven by the turbine (1).

[0063] According to the configuration of 7) above, the supercharger (10) includes a turbine (1) with improved robustness.

Explanation of Reference Numerals

[0064] 1, 1A Turbine 2 Impeller (Turbine Impeller) 3 Casing 4, 4A Hub-side flow path surface 5 Shroud-side flow path surface 6 Nozzle vane 10 Supercharger 11 Centrifugal compressor 12 Compressor impeller 13 Rotating shaft 14 Engine 21 Hub 22 Outer surface 23 Impeller blade 24 Tip 25 Leading edge 26 Hub-side end 31 Shroud surface 32 Shroud part 33 Scroll flow path 34 Scroll flow path forming part 35 Exhaust gas flow path 36 Exhaust gas flow path forming part 40, 40A Annular member 41 Flat surface 42 Step 43 Inner inclined surface 44 Outer inclined surface 61 Leading edge 62, 62A Trailing edge 63, 63A Inner blade surface 64, 64A Outer blade surface CL Blade thickness center line D1, D2 Distance ETA Effective nozzle throat area LA Axis SL Surging limit T Throat TL1, TL2 Tangent line VC Virtual circle VL Virtual extension surface W0 Flow path width W1 Blade height

Claims

Claim 1. A turbine impeller, and an exhaust gas flow path forming portion that forms an exhaust gas flow path for guiding exhaust gas from a scroll flow path formed on an outer peripheral side of the turbine impeller to the turbine impeller, the exhaust gas flow path forming portion including a hub side flow surface and a shroud side flow surface that define the exhaust gas flow path; at least one fixed nozzle vane disposed in the exhaust gas flow path and non-rotatably fixed to at least one of the hub side flow surface or the shroud side flow surface; a blade height W1, which is a length of the at least one fixed nozzle vane in an axial direction of the turbine impeller, is smaller than a flow path width W0, which is a length of the exhaust gas flow path in the axial direction at a leading edge position of a blade of the turbine impeller; the hub side flow surface is a flat surface formed in a region sandwiching the at least one fixed nozzle vane between the hub side flow surface and the shroud side flow surface, and includes a flat surface located on a shroud side of a hub side end of a leading edge of an impeller blade of the turbine impeller in the axial direction and extending along a radial direction of the turbine impeller; the flow path width W0 is based on a hub side end of the leading edge of the impeller blade of the turbine impeller; a turbine. Claim 2. the hub side flow surface further includes an inner inclined surface that is inclined toward the hub side as it goes inward in the radial direction of the turbine impeller, inside the flat surface; The turbine according to claim 1. Claim 3. the hub side flow surface further includes an outer inclined surface that is inclined toward the hub side as it goes outward in the radial direction of the turbine impeller, outside the flat surface; The turbine according to claim 1 or 2. Claim 4. the exhaust gas flow path forming portion is an annular member having the hub side flow surface, and includes an annular member configured separately from a casing that rotatably houses the turbine impeller; the at least one fixed nozzle vane includes a plurality of fixed nozzle vanes arranged at intervals in a circumferential direction of the turbine impeller; each of the plurality of fixed nozzle vanes is integrally formed with the annular member; an inner peripheral edge of the inner inclined surface constitutes an inner peripheral edge of the annular member; The turbine according to claim 2. Claim 5. The exhaust gas flow path forming portion includes an annular member having the hub side flow surface, and includes an annular member configured separately from the casing that rotatably houses the turbine impeller. The at least one fixed nozzle vane includes a plurality of fixed nozzle vanes arranged at intervals in the circumferential direction of the turbine impeller. Each of the plurality of fixed nozzle vanes is integrally formed with the annular member. The outer peripheral edge of the outer inclined surface constitutes the outer peripheral edge of the annular member. The turbine according to claim 3.

6. The turbine according to claim 1, and a centrifugal compressor configured to be driven by the turbine. Supercharger.

Images