Turbine and turbo device

Abstract

This turbine comprises: a turbine wheel; a turbine housing that rotatably accommodates the turbine wheel and defines an annular nozzle flow path on an outer peripheral side of the turbine wheel; a plurality of long nozzle vanes that are provided offset in a circumferential direction so as not to overlap in a radial direction in the nozzle flow path; and a short nozzle vane that is provided between two long nozzle vanes which are adjacent to each other in the circumferential direction among the plurality of long nozzle vanes, and in which the length of a straight line connecting a front edge and a rear edge of the short nozzle vane is shorter than that of the long nozzle vane. The short nozzle vane is provided on a front-edge circumscribed circle that passes through the front edge of each of the two long nozzle vanes which are adjacent to each other in the circumferential direction.

Description

Turbines and turbo equipment

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

[0002] Patent Document 1 discloses a turbine equipped with low solidity nozzle vanes in which the trailing edge inscribed circumference of each nozzle vane located upstream of the turbine wheel is made longer than the chord length of the nozzle vane in order to achieve high turbine efficiency in response to exhaust pulsation from the engine.

[0003] Japanese Patent Application Laid-Open No. 2018-123802

[0004] In the low solidity nozzle vanes described in Patent Document 1, the nozzle vane blades are short, which may prevent the nozzle vanes from fully performing one of their functions of changing the direction of upstream flow. Therefore, it is necessary to direct fluid into the nozzle flow passage at an angle similar to the inlet angle of the turbine wheel. In this case, it is necessary to design a scroll flow passage that increases the circumferential component of the flow compared to turbines with conventional nozzle vanes. However, this requires a smaller scroll cross-sectional area, which may increase losses.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure has an object to provide a turbine that can exhibit high turbine efficiency in response to exhaust pulsations of an engine, and a turbo device including the turbine.

[0006] A turbine according to at least one embodiment of the present disclosure comprises: a turbine wheel; a turbine housing configured to rotatably accommodate the turbine wheel and defining an annular nozzle flow path on the outer periphery of the turbine wheel; a plurality of long nozzle vanes arranged circumferentially offset in the nozzle flow path so as not to overlap radially; and at least one short nozzle vane arranged between two circumferentially adjacent long nozzle vanes among the plurality of long nozzle vanes, the short nozzle vane having a length of a straight line connecting its leading edge and trailing edge shorter than that of the long nozzle vane, wherein the at least one short nozzle vane is arranged on a leading edge circumscribing circle passing through the leading edges of each of the two circumferentially adjacent long nozzle vanes.

[0007] A turbo device according to at least one embodiment of the present disclosure includes the turbine.

[0008] According to at least one embodiment of the present disclosure, a turbine capable of exhibiting high turbine efficiency in response to exhaust pulsations of an engine and a turbo device including the turbine are provided.

[0009] FIG. 1 is a schematic cross-sectional view of a turbocharger including a turbine according to an embodiment of the present disclosure; FIG. 2 is a schematic view of a turbine according to an embodiment of the present disclosure viewed from one side in the axial direction; FIG. 3 is a schematic view of a turbine according to an embodiment of the present disclosure viewed from one side in the axial direction; FIG. 4 is a schematic view of a turbine according to an embodiment of the present disclosure viewed from one side in the axial direction; FIG. 5 is a schematic cross-sectional view of a turbine according to an embodiment of the present disclosure viewed from one side in the axial direction, taken along the circumferential direction in the vicinity of a short-bladed nozzle vane of a turbine according to an embodiment of the present disclosure;

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

[0011] (Turbine, Turbo Device) Fig. 1 is a schematic cross-sectional view of a turbocharger 10 including a turbine 1 according to one embodiment of the present disclosure. Each of Figs. 2 to 6 is a front view of the turbine 1 according to one embodiment of the present invention as viewed along the axial direction. The symbol N in Figs. 2 to 6 indicates the rotation direction of a turbine wheel 2. A turbocharger 10 (turbo device) according to some embodiments includes a radial turbine 1 (turbine), as shown in Fig. 1. As shown in Fig. 1, the radial turbine 1 includes a turbine wheel 2 that rotates about an axis RA, a turbine housing 3 configured to rotatably house the turbine wheel 2, and a plurality of elongated nozzle vanes 4.

[0012] Hereinafter, the direction in which the axis RA of the turbine wheel 2 extends is defined as the axial direction of the turbine wheel 2 (turbine 1), the direction perpendicular to the axis RA is defined as the radial direction of the turbine wheel 2 (turbine 1), and the circumferential direction around the axis RA is defined as the circumferential direction of the turbine wheel 2 (turbine 1). Hereinafter, the axial direction, radial direction, and circumferential direction of the turbine wheel 2 (turbine 1) may be simply referred to as the axial direction, radial direction, and circumferential direction.

[0013] The turbine housing 3 defines an annular nozzle flow path 31 on the outer circumferential side of the turbine wheel 2. As shown in FIGS. 2 to 6 , each of the multiple long nozzle vanes 4 has a leading edge 41, a trailing edge 42, a pressure surface 43, and a suction surface 44. The pressure surface 43 and the suction surface 44 are each a blade surface extending from the leading edge 41 to the trailing edge 42. The pressure surface 43 is located upstream of the suction surface 44 in the direction of rotation N. As shown in FIGS. 2 to 6 , each of the multiple long nozzle vanes 4 is circumferentially offset in the nozzle flow path 31 so as not to overlap radially. In other words, a circumferential gap is formed between the leading edge 41 of one of two circumferentially adjacent long nozzle vanes 4 and the trailing edge 42 of the other.

[0014] In the embodiment shown in FIG. 1 , the turbine wheel 2 includes a truncated cone-shaped turbine hub 21 provided on one axial side of the rotating shaft 11, and a plurality of turbine blades 22 provided at intervals in the circumferential direction on the circumferential surface of the turbine hub 21. The rotating shaft 11 is rotatably supported by journal bearings 13A, 13B housed in a bearing housing 12. A truncated cone-shaped compressor hub 141 is provided on the other axial side of the rotating shaft 11. A plurality of compressor blades 142 are provided at intervals in the circumferential direction on the circumferential surface of the compressor hub 141. The compressor impeller 14 is composed of the compressor hub 141 and the compressor blades 142. The compressor impeller 14 is housed in a compressor housing 15 in a state where it can rotate about an axis RA.

[0015] In the embodiment shown in FIG. 1 , in addition to the nozzle passage 31 described above, a scroll passage 32 through which exhaust gas introduced from outside the turbine housing 3 flows, and an outlet passage 33 through which exhaust gas that has driven the turbine wheel 2 is discharged to the outside of the turbine housing 3 are formed inside the turbine housing 3. The scroll passage 32 is a spiral passage formed on the outer periphery of the nozzle passage 31. The outlet passage 33 is a tubular passage extending along the axial direction. The exhaust gas that has flowed through the scroll passage 32 flows radially inward through the nozzle passage 31 and flows into the turbine wheel 2, causing the turbine wheel 2 to rotate. The exhaust gas that has driven the turbine wheel 2 to rotate then flows through the outlet passage 33 along the axial direction and is discharged to the outside of the turbine housing 3.

[0016] (Long Nozzle Vanes) In the embodiment shown in FIG. 1 , the above-described plurality of long nozzle vanes 4 are configured as variable nozzle vanes rotatably attached to the turbine housing 3. The variable nozzle vanes are rotatably supported between a nozzle mount 6 and a nozzle plate 7, which are arranged facing each other with a nozzle flow path 31 in between. The variable nozzle vanes are configured to rotate when a driving force from an actuator 16 is transmitted via a variable mechanism 17. The nozzle mount 6 and the nozzle plate 7 are each annular plate-shaped members having an opening in the center, and have flow path surfaces that form the nozzle flow path 31. The nozzle mount 6 and the nozzle plate 7 are connected by a nozzle support 8. In the embodiment shown in FIG. 1 , the turbine 1 includes the nozzle mount 6, the nozzle plate 7, and the nozzle support 8.

[0017] The above-described plurality of long nozzle vanes 4 may be configured as fixed nozzle vanes that are non-rotatably attached to the turbine housing 3. The fixed nozzle vanes are fixed non-rotatably to at least one of the nozzle mount 6 and the flow path surface of the nozzle plate 7 that define the nozzle flow path 31. When the long nozzle vanes 4 are configured as fixed nozzle vanes, there is no need for components for rotating the long nozzle vanes 4, such as the actuator 16 and variable mechanism 17 shown in Figure 1. Furthermore, when a flow path surface that forms the nozzle flow path 31 is provided in the turbine housing 3, the nozzle plate 7 is not required.

[0018] 2 , each of the plurality of long nozzle vanes 4 of the turbine 1 according to some embodiments is a low solidity nozzle vane configured to satisfy Lvf < Lcf / Nvf, where Lvf is the length of a straight line connecting the leading edge 41 and the trailing edge 42 of the long nozzle vane 4 (vane length), Lcf is the perimeter of a trailing edge inscribed circle C1 passing through the trailing edge 42 of each of the plurality of long nozzle vanes 4, and Nvf is the number of the plurality of long nozzle vanes 4. That is, in each of the plurality of long nozzle vanes 4, adjacent long nozzle vanes 4 do not overlap in the circumferential direction, and an inter-nozzle vane throat is formed between the leading edge 41 of one nozzle vane 4 of a pair of adjacent nozzle vanes 4A, 4B and the trailing edge 42 of the nozzle vane 4 of the other nozzle vane. Here, the inter-nozzle vane throat refers to a portion forming the smallest width between adjacent long nozzle vanes in the circumferential direction. The throat th refers to the portion that forms the smallest width between adjacent nozzle vanes in the circumferential direction, without distinguishing between the long nozzle vanes 4 and the short nozzle vanes 5 .

[0019] In addition, when the long nozzle vanes 4 are variable nozzle vanes, the above-mentioned conditional expression Lvf<Lcf / Nvf is satisfied when the variable nozzle vanes are in a fully closed state.

[0020] (Short Nozzle Vane) As shown in Figures 2 to 6, the turbine 1 according to some embodiments further includes at least one short nozzle vane 5 provided between two circumferentially adjacent long nozzle vanes 4A, 4B among the plurality of long nozzle vanes 4 described above. As shown in Figures 2 to 6, the short nozzle vane 5 has a leading edge 51, a trailing edge 52, a pressure surface 53, and a suction surface 54. Each of the pressure surface 53 and the suction surface 54 is a blade surface extending from the leading edge 51 to the trailing edge 52. The pressure surface 53 is located upstream of the suction surface 54 in the direction of rotation N. In the short nozzle vane 5, the length of the straight line connecting the leading edge 51 and the trailing edge 52 (chord length Lvs, see Figure 2) is shorter than the chord length of the long nozzle vane 4.

[0021] The above-mentioned short nozzle vane 5 is provided on a leading edge circumscribing circle C2 that passes through the leading edges 41 of the two circumferentially adjacent long nozzle vanes 4A, 4B. Since the short nozzle vane 5 has a shorter chord length than the long nozzle vane 4, the trailing edge 52 is located radially outward of the trailing edge inscribing circle C1.

[0022] At least one short nozzle vane 5 provided between two circumferentially adjacent long nozzle vanes 4A, 4B has a throat th formed between its pressure surface 53 and the trailing edge 42 of the long nozzle vane 4A located upstream in the rotational direction N.

[0023] In the illustrated embodiment, the above-mentioned short nozzle vanes 5 are configured as fixed nozzle vanes that are attached non-rotatably to the turbine housing 3. For example, the fixed nozzle vanes are fixed non-rotatably to at least one of the flow path surfaces of the nozzle mount 6 and the nozzle plate 7 that define the nozzle flow path 31. Furthermore, if the turbine housing 3 has a flow path surface that defines the nozzle flow path 31, the fixed nozzle vanes may be fixed non-rotatably to the flow path surface of the turbine housing 3.

[0024] On the upstream side of the nozzle flow path 31 where the short nozzle vanes 5 are provided, the short nozzle vanes 5 can guide the flow of fluid flowing in from the scroll flow path 32. Furthermore, on the downstream side of the nozzle flow path 31 where the short nozzle vanes 5 are not provided, the inter-blade distance between the two nozzle vanes (long nozzle vanes 4A, 4B) can be made large, and the long nozzle vanes 4 can function as low solidity nozzle vanes.

[0025] Specifically, on the downstream side of the nozzle flow path 31, the pulsating flow can vary the outlet outlet angle of the nozzle flow path 31. As a result, when the flow rate fluctuation due to the pulsation is high, the flow becomes more radial. Furthermore, when the flow rate fluctuation due to the pulsation is low, the circumferential component increases, thereby reducing the fluctuation in the relative inflow angle to the turbine wheel 2. Therefore, the above-described turbine 1 can exhibit high turbine efficiency in response to exhaust pulsation from the engine.

[0026] 2 , the turbine 1 according to some embodiments is configured so that the leading edge 51 of the at least one short nozzle vane 5 described above is located at the same radial position as the leading edge 41 of the long nozzle vane 4. In other words, the leading edge 51 of the short nozzle vane 5 is located on the leading edge circumscribing circle C2. In this case, the short nozzle vane 5 can guide the fluid flow upstream of the nozzle flow path 31.

[0027] 3 , the turbine 1 according to some embodiments is configured such that the leading edge 51 of at least one short nozzle vane 5 described above is positioned radially outward of the leading edge 41 of the long nozzle vane 4. In this case, the short nozzle vane 5 can guide the fluid flow upstream of the nozzle flow path 31. Furthermore, by positioning the leading edge 51 of the short nozzle vane 5 radially outward of the leading edge 41 of the long nozzle vane 4, the chord length of the short nozzle vane 5 can be increased, and the short nozzle vane 5 can guide the fluid flow over a relatively wide range in the nozzle flow path 31.

[0028] As shown in Figure 2, the turbine 1 according to some embodiments is configured to satisfy 2 x (Nvs / Nvf) x Lvs < Lcf / Nvf, where Lvs is the length (chord length) of the straight line connecting the leading edge 51 and the trailing edge 52 of the short nozzle vane 5, Lcf is the perimeter of the trailing edge inscribed circle C1 passing through the trailing edge 42 of each of the multiple long nozzle vanes 4, Nvs is the number of at least one short nozzle vane 5, and Nvf is the number of multiple long nozzle vanes 4.

[0029] When the above conditional expression 2×(Nvs / Nvf)×Lvs<Lcf / Nvf is satisfied, the chord length Lvs of the short nozzle vanes 5 becomes suitable, and the short nozzle vanes 5 can suitably perform the functions of guiding the fluid flow and varying the outlet outlet angle of the nozzle flow path 31 by the pulsating flow. This makes it possible to achieve higher turbine efficiency in response to exhaust pulsations of the engine. Note that when the long nozzle vanes 4 are variable nozzle vanes, the above conditional expression 2×(Nvs / Nvf)×Lvs<Lcf / Nvf is satisfied when the variable nozzle vanes are fully closed.

[0030] 2 to 5 , in the turbine 1 according to some embodiments, the at least one short nozzle vane 5 includes a plurality of short nozzle vanes 5 spaced apart in the circumferential direction. The plurality of short nozzle vanes 5 are each provided between two circumferentially adjacent long nozzle vanes 4A, 4B. In this case, the structure of the turbine 1 can be simplified compared to when a plurality of short nozzle vanes 5 are provided between two circumferentially adjacent long nozzle vanes 4A, 4B.

[0031] 6 , in the turbine 1 according to some embodiments, the at least one short nozzle vane 5 includes a plurality of short nozzle vanes 5 spaced apart in the circumferential direction. The plurality of short nozzle vanes 5 includes two or more (two in the illustrated example) short nozzle vanes 5 provided between each pair of circumferentially adjacent long nozzle vanes 4A, 4B. In this case, by increasing the number of short nozzle vanes 5 provided between each pair of circumferentially adjacent long nozzle vanes 4A, 4B, the fluid flow can be guided by the plurality of short nozzle vanes 5 on the upstream side of the nozzle flow path 31.

[0032] 2 , in the turbine 1 according to some embodiments, the at least one short nozzle vane 5 is provided at a circumferential position including a midpoint CP of the arc between the leading edges 41, 41 of the leading edge circumscribing circle C2 that passes through the leading edges 41 of two circumferentially adjacent long nozzle vanes 4A, 4B. By providing the short nozzle vane 5 at a circumferential position including the midpoint CP, the length of the throat th formed between the pressure surface 53 of the short nozzle vane 5 and the trailing edge 42 of the long nozzle vane 4A located upstream in the rotational direction N can be made appropriate.

[0033] 4 and 5, for reference, short nozzle vanes 5 provided at circumferential positions including the middle CP are indicated by two-dot chain lines. In the turbine 1 according to some embodiments, as shown in FIG. 4, at least one short nozzle vane 5 described above is provided upstream of the middle CP described above in the rotational direction N of the turbine wheel 2. The pressure surface 53 of the short nozzle vane 5 has a larger angle change than the suction surface 54, and therefore has a greater effect on the outlet flow angle. By providing the short nozzle vane 5 upstream of the middle CP in the rotational direction N, it is possible to increase the fluctuation in the outlet outlet flow angle of the nozzle flow path 31 due to the pulsating flow.

[0034] 5 , in the turbine 1 according to some embodiments, the at least one short nozzle vane 5 is provided downstream of the middle CP in the rotational direction N of the turbine wheel 2. The pressure surface 53 of the short nozzle vane 5 has a larger angle change than the suction surface 54, and therefore has a greater effect on the outlet flow angle. By providing the short nozzle vane 5 downstream of the middle CP in the rotational direction N, it is possible to reduce fluctuations in the outlet outlet flow angle of the nozzle flow path 31 due to pulsating flow.

[0035] Fig. 7 is a schematic cross-sectional view along the circumferential direction near a short-blade nozzle vane 5 of a turbine 1 according to an embodiment of the present disclosure. In the turbine 1 according to some embodiments, as shown in Fig. 7, the nozzle mount 6 (plate-shaped member) described above includes an annular plate portion 61 having a flow path surface 62 facing the nozzle flow path 31 and a back surface 63 spaced apart from the nozzle flow path 31 in the axial direction of the turbine wheel 2 with respect to the flow path surface 62. The short nozzle vane 5 described above includes at least a blade surface forming portion 55 forming the blade surfaces (pressure surface 53, suction surface 54) facing the nozzle flow path 31, and an insertion portion 56 that passes through a through-hole 64 formed in the flow path surface 62 of the nozzle mount 6, and is formed by plastic working a metal plate.

[0036] In the illustrated embodiment, the blade surface forming portion 55 has a side portion that forms the pressure surface 53, a side portion that forms the suction surface 54, and a side portion 551 that connects these side portions and abuts against the flow path surface of the nozzle plate 7. The side portion 551 extends in a direction that intersects with the axial direction (orthogonal in the illustrated example).

[0037] Forming the short nozzle vanes 5 by plastically working a metal plate reduces the manufacturing costs of the short nozzle vanes 5. Furthermore, the short nozzle vanes 5 include insertion portions 56 that pass through through holes 64 formed in the flow path surface 62 of the nozzle mount 6 (plate-shaped member), making them easy to attach to the nozzle mount 6.

[0038] In the illustrated embodiment, the short nozzle vane 5 further includes a biasing portion 57 configured to bias the nozzle mount 6 (plate-shaped member) toward the nozzle flow path 31. The shape of the biasing portion 57 is formed by plastically processing a metal plate. By supporting the plate-shaped member 6 with the short nozzle vane 5 including the biasing portion 57 that is allowed to deform in the axial direction, structural errors in the nozzle flow path 31 that occur due to changes in the operating state of the turbomachine 10 can be tolerated, and therefore, the clearance of the long nozzle vane 4 that tends to occur on the turbine housing 3 side of the nozzle flow path 31 can be reduced.

[0039] In the illustrated embodiment, the biasing portion 57 includes a first radially extending portion 571, an axially extending portion 572, and a second radially extending portion 573. The first radially extending portion 571 extends radially outward, and at least a portion of the first radially extending portion 571 abuts against the back surface 63 of the nozzle mount 6 (plate-shaped member). The axially extending portion 572 has one end connected to the radially outer end of the first radially extending portion 571 and extends away from the nozzle flow path 31 in the axial direction. The second radially extending portion 573 extends radially inward from the other end of the axially extending portion 572, and at least a portion of the second radially extending portion 573 abuts against the opposing surface 121 of another member (the bearing housing 12 in the illustrated example) that faces the back surface 63 of the nozzle mount 6 (plate-shaped member) across an axial gap. In this case, the biasing portion 57 has a simple structure that can be easily formed by plastic processing a metal plate, and is capable of exerting a biasing force. Note that in some other embodiments, the above-mentioned plate-like member may be the nozzle plate 7.

[0040] In the turbine 1 according to some embodiments, each of the plurality of long nozzle vanes 4 described above is a variable nozzle vane that is rotatably provided with respect to the turbine housing 3. When the long nozzle vanes 4 are configured as variable nozzle vanes, the turbine 1 can exhibit high turbine efficiency in response to exhaust pulsations of the engine.

[0041] In the turbine 1 according to some embodiments, each of the plurality of long nozzle vanes 4 described above is a fixed nozzle vane that is non-rotatable relative to the turbine housing 3. When the long nozzle vanes 4 are configured as fixed nozzle vanes, the turbine 1 can exhibit high turbine efficiency in response to exhaust pulsations of the engine.

[0042] As shown in Fig. 1, a turbo device (turbocharger 10) according to some embodiments includes the above-described turbine 1. Since the turbine 1 can exhibit high turbine efficiency in response to exhaust pulsation of the engine, the efficiency of the turbo device (turbocharger 10) can be improved.

[0043] In this specification, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions expressing that things are in an equal state, such as "identical," "equal," and "homogeneous," not only express a state in which there is a strict equivalence, but also express a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions expressing shapes such as a rectangular shape or a cylindrical shape not only express shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components.

[0044] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0045] The contents of the above-described embodiments can be understood, for example, as follows.

[0046] 1) A turbine (1) according to at least one embodiment of the present disclosure comprises: a turbine wheel (2); a turbine housing (3) configured to rotatably accommodate the turbine wheel (2) and defining an annular nozzle flow path (31) on the outer circumferential side of the turbine wheel (2); a plurality of long nozzle vanes (4) arranged in the nozzle flow path (31) and offset in the circumferential direction so as not to overlap in the radial direction; and at least one short nozzle vane (5) arranged between two of the long nozzle vanes (4A, 4B) adjacent in the circumferential direction and having a length of a straight line (53) connecting a leading edge (51) and a trailing edge (52) shorter than that of the long nozzle vane (4), wherein the at least one short nozzle vane (5) is arranged on a leading edge circumscribing circle (C2) passing through the leading edges (41) of the two circumferentially adjacent long nozzle vanes (4A, 4B).

[0047] According to the configuration 1), the flow of fluid can be guided by the short nozzle vanes (5). Furthermore, since the short nozzle vanes (5) are not provided downstream of the nozzle flow path, the blade-to-blade distance between the two nozzle vanes (long nozzle vanes 4A, 4B) can be increased, and the outlet outlet angle of the nozzle flow path (31) can be varied by the pulsating flow. As a result, when the flow rate fluctuation due to pulsation is high, the flow becomes more radial. Furthermore, when the flow rate fluctuation due to pulsation is low, the circumferential component increases, thereby reducing the variation in the relative inflow angle to the turbine wheel (2). Therefore, according to the configuration 1), high turbine efficiency can be achieved in response to exhaust pulsation from the engine.

[0048] 2) In some embodiments, the turbine (1) described in 1) above is configured such that the leading edge (51) of the at least one short nozzle vane (5) is located at the same radial position as the leading edge (41) of the long nozzle vane (4).

[0049] According to the configuration 2) above, the flow of the fluid can be guided by the short nozzle vane (5) on the upstream side of the nozzle flow path (31).

[0050] 3) In some embodiments, the turbine (1) described in 1) above is configured such that the leading edge (51) of the at least one short nozzle vane (5) is positioned radially outward of the leading edge (41) of the long nozzle vane (4).

[0051] According to the configuration 3), the short nozzle vanes 5 can guide the flow of fluid upstream of the nozzle flow path 31. Furthermore, by positioning the leading edges 51 of the short nozzle vanes 5 radially outward of the leading edges 41 of the long nozzle vanes 4, the chord length of the short nozzle vanes 5 can be increased, and the short nozzle vanes 5 can guide the flow of fluid over a relatively wide area in the nozzle flow path 31.

[0052] 4) In some embodiments, the turbine (1) according to any one of 1) to 3) above is configured to satisfy the relationship 2×(Nvs / Nvf)×Lvs<Lcf / Nvf, where Lvs is the length of a straight line connecting the leading edge (51) and the trailing edge (52) of the short nozzle vane (5), Lcf is the perimeter of a trailing edge inscribed circle passing through the trailing edge (42) of each of the plurality of long nozzle vanes (4), Nvs is the number of the at least one short nozzle vane (5), and Nvf is the number of the plurality of long nozzle vanes (4).

[0053] According to the configuration of 4) above, when the conditional expression 2×(Nvs / Nvf)×Lvs<Lcf / Nvf is satisfied, the chord length (Lvs) of the short nozzle vanes (5) becomes suitable, and the short nozzle vanes (5) can suitably perform the functions of guiding the fluid flow and varying the outlet outlet angle of the nozzle flow path (31) by the pulsating flow. This allows for higher turbine efficiency to be achieved in response to engine exhaust pulsation.

[0054] 5) In some embodiments, the turbine (1) is described in any one of 1) to 4) above, wherein the at least one short nozzle vane (5) includes a plurality of short nozzle vanes (5) spaced apart in the circumferential direction, and the plurality of short nozzle vanes (5) are each provided between two of the long nozzle vanes (4A, 4B) adjacent to each other in the circumferential direction.

[0055] According to the configuration of 5) above, the structure of the turbine (1) can be simplified compared to a case where a plurality of short nozzle vanes (5) are provided between two circumferentially adjacent long nozzle vanes (4A, 4B).

[0056] 6) In some embodiments, in the turbine (1) described in any one of 1) to 4) above, the at least one short nozzle vane (5) includes a plurality of short nozzle vanes (5) spaced apart in the circumferential direction, and the plurality of short nozzle vanes (5) are arranged such that two or more of the same number of short nozzle vanes (5) are provided between each of the two long nozzle vanes (4A, 4B) adjacent to each other in the circumferential direction.

[0057] According to the configuration of 6) above, by increasing the number of short nozzle vanes (5) provided between two circumferentially adjacent long nozzle vanes (4A, 4B), the flow of fluid can be guided by the multiple short nozzle vanes (5) on the upstream side of the nozzle flow path (31).

[0058] 7) In some embodiments, in the turbine (1) described in any one of 1) to 6) above, the at least one short nozzle vane (5) is provided at a circumferential position including the midpoint (CP) of the arc between the leading edges (41) of a leading edge circumscribing circle (C2) passing through the leading edges (41) of the two circumferentially adjacent long nozzle vanes (4A, 4B).

[0059] According to the configuration of 7) above, by providing the short nozzle vane (5) at a circumferential position including the middle (CP), the length of the throat (th) formed between the pressure surface (53) of the short nozzle vane (5) and the trailing edge (42) of the long nozzle vane (4A) located upstream in the rotation direction (N) can be made appropriate.

[0060] 8) In some embodiments, in the turbine (1) described in any one of 1) to 6) above, the at least one short nozzle vane (5) is provided upstream in the rotation direction of the turbine wheel (2) of the midpoint of an arc between the leading edges (41) of a leading edge circumscribing circle passing through the leading edges (41) of the two circumferentially adjacent long nozzle vanes (4A, 4B).

[0061] According to the configuration of 8), the pressure surface (53) of the short nozzle vane (5) has a larger angle change than the suction surface (54), and therefore has a larger effect on the outlet flow angle. By providing the short nozzle vane (5) upstream of the middle (CP) in the direction of rotation (N), it is possible to make the fluctuation of the outlet flow angle of the nozzle flow path 31 due to the pulsating flow larger.

[0062] 9) In some embodiments, in the turbine (1) described in any one of 1) to 6) above, the at least one short nozzle vane (5) is provided downstream in the rotation direction of the turbine wheel (2) of the midpoint (CP) of the arc between the leading edges (41) of a leading edge circumscribing circle passing through the leading edges (41) of the two circumferentially adjacent long nozzle vanes (4A, 4B).

[0063] According to the configuration of 9), the pressure surface (53) of the short nozzle vane (5) has a larger angle change than the suction surface (54), and therefore has a larger effect on the outlet flow angle. By providing the short nozzle vane (5) downstream of the middle (CP) in the direction of rotation (N), it is possible to reduce fluctuations in the outlet flow angle of the nozzle flow path 31 due to pulsating flow.

[0064] 10) In some embodiments, the turbine (1) according to any one of 1) to 9) above further comprises a plate-like member (nozzle mount 6) including an annular plate portion (61) having a flow path surface (62) facing the nozzle flow path (31) and a back surface (63) spaced apart from the nozzle flow path (31) in the axial direction of the turbine wheel (2) with respect to the flow path surface (62), and the at least one short nozzle vane (5) includes at least a blade surface forming portion (55) forming a blade surface (pressure surface 53, suction surface 54) facing the nozzle flow path (31), and an insertion portion (56) inserted into a through hole (64) formed in the flow path surface (62) of the plate-like member (6), and is formed by plastically working a metal plate.

[0065] According to the configuration of 10), the short nozzle vane (5) is formed by plastically working a metal plate, thereby reducing the manufacturing cost of the short nozzle vane (5). In addition, the short nozzle vane (5) includes an insertion portion (56) that passes through a through hole (64) formed in the flow path surface (62) of the plate-shaped member (6), making it easy to attach the short nozzle vane (5) to the plate-shaped member (6).

[0066] 11) In some embodiments, the turbine (1) described in 10) above, wherein the at least one short nozzle vane (5) further includes a biasing portion (57) configured to bias the plate-shaped member (6) toward the nozzle flow path (31).

[0067] According to the configuration of 11), the plate-like member (6) is supported by the short nozzle vane (5) including the biasing portion (57) that allows deformation in the axial direction, and therefore structural errors in the nozzle flow path (31) caused by changes in the operating state of the turbomachine (10) can be tolerated, and therefore it is possible to reduce the clearance of the long nozzle vane (4) that tends to occur on the turbine housing (3) side of the nozzle flow path (31).

[0068] 12) In some embodiments, in the turbine (1) described in 11) above, the biasing portion (57) comprises: a first radially extending portion (571) extending radially outward and having at least a portion abutting the back surface (63) of the plate-shaped member (6); an axially extending portion (572) having one end connected to the radially outer end of the first radially extending portion (571) and extending to a side away from the nozzle flow path (31) in the axial direction; and a second radially extending portion (573) extending radially inward from the other end of the axially extending portion (572) and having at least a portion abutting an opposing surface (121) of another member (bearing housing 12) that faces the back surface (63) of the plate-shaped member (6) across an axial gap.

[0069] According to the above configuration 12), the biasing portion (57) has a simple structure that can be easily formed by plastically processing a metal plate, and is capable of exerting a biasing force.

[0070] 13) In some embodiments, the turbine (1) is described in any one of 1) to 12) above, wherein each of the plurality of long nozzle vanes (4) is a variable nozzle vane rotatably provided with respect to the turbine housing (3).

[0071] According to the configuration of 13) above, when the long nozzle vane (4) is configured as a variable nozzle vane, the turbine (1) can exhibit high turbine efficiency against exhaust pulsation of the engine.

[0072] 14) In some embodiments, the turbine (1) is described in any one of 1) to 12) above, wherein each of the plurality of long nozzle vanes (4) is a fixed nozzle vane that is non-rotatable relative to the turbine housing (3).

[0073] According to the configuration of 14) above, when the long nozzle vanes (4) are configured as fixed nozzle vanes, the turbine (1) can exhibit high turbine efficiency against exhaust pulsation of the engine.

[0074] 15) A turbo device (10) according to at least one embodiment of the present disclosure includes the turbine (1) described in any one of 1) to 14) above.

[0075] According to the configuration of 15) above, the turbine (1) can exhibit high turbine efficiency against exhaust pulsation of the engine, thereby improving the efficiency of the turbo device (10).

[0076] REFERENCE SIGNS LIST 1 turbine 2 turbine wheel 3 turbine housing 4 long nozzle vane 5 short nozzle vane 6 nozzle mount 7 nozzle plate 8 nozzle support 10 turbocharger 11 rotating shaft 12 bearing housing 13A, 13B journal bearing 14 compressor impeller 15 compressor housing 31 nozzle flow passage 32 scroll flow passage 33 outlet flow passage 41, 51 leading edge 42, 52 trailing edge

Claims

1. A turbine comprising: a turbine wheel; a turbine housing configured to rotatably accommodate the turbine wheel and defining an annular nozzle flow path on the outer periphery of the turbine wheel; a plurality of long nozzle vanes arranged circumferentially offset in the nozzle flow path so as not to overlap radially; and at least one short nozzle vane arranged between two circumferentially adjacent long nozzle vanes among the plurality of long nozzle vanes, the short nozzle vane having a length of a straight line connecting its leading edge and trailing edge shorter than that of the long nozzle vane, wherein the at least one short nozzle vane is arranged on a leading edge circumscribing circle passing through the leading edges of the two circumferentially adjacent long nozzle vanes.

2. The turbine according to claim 1, wherein the at least one short nozzle vane is configured such that the leading edge is located at the same radial position as the leading edge of the long nozzle vane.

3. The turbine according to claim 1, wherein the at least one short nozzle vane is configured such that the leading edge is positioned radially outward of the leading edge of the long nozzle vane.

4. A turbine according to any one of claims 1 to 3, configured to satisfy the relationship 2 x (Nvs / Nvf) x Lvs < Lcf / Nvf, where Lvs is the length of a straight line connecting the leading edge and trailing edge of the short nozzle vane, Lcf is the perimeter of a trailing edge inscribed circle passing through the trailing edge of each of the plurality of long nozzle vanes, Nvs is the number of the at least one short nozzle vane, and Nvf is the number of the plurality of long nozzle vanes.

5. A turbine according to any one of claims 1 to 3, wherein the at least one short nozzle vane includes a plurality of short nozzle vanes spaced apart in the circumferential direction, and wherein one of the plurality of short nozzle vanes is provided between each of the two long nozzle vanes adjacent in the circumferential direction.

6. A turbine according to any one of claims 1 to 3, wherein the at least one short nozzle vane includes a plurality of short nozzle vanes spaced apart in the circumferential direction, and the plurality of short nozzle vanes are provided such that an equal number of two or more short nozzle vanes are provided between each of the two long nozzle vanes adjacent in the circumferential direction.

7. A turbine according to any one of claims 1 to 3, wherein the at least one short nozzle vane is provided at a circumferential position including the middle of an arc between the leading edges of a leading edge circumscribing circle that passes through the leading edges of each of the two circumferentially adjacent long nozzle vanes.

8. A turbine according to any one of claims 1 to 3, wherein the at least one short nozzle vane is provided upstream in the rotation direction of the turbine wheel of the midpoint of an arc between the leading edges of a leading edge circumscribing circle that passes through the leading edges of each of the two circumferentially adjacent long nozzle vanes.

9. A turbine according to any one of claims 1 to 3, wherein the at least one short nozzle vane is provided downstream in the rotation direction of the turbine wheel from the midpoint of an arc between leading edges of a leading edge circumscribing circle that passes through the leading edges of each of the two circumferentially adjacent long nozzle vanes.

10. A turbine according to any one of claims 1 to 3, further comprising a plate-like member including an annular plate portion having a flow path surface facing the nozzle flow path and a back surface spaced apart from the nozzle flow path in the axial direction of the turbine wheel relative to the flow path surface, wherein the at least one short nozzle vane includes at least a blade surface forming portion that forms a blade surface facing the nozzle flow path, and an insertion portion that passes through a through hole formed in the flow path surface of the plate-like member, and is formed by plastically working a metal plate.

11. The turbine according to claim 10, wherein the at least one short nozzle vane further includes a biasing portion configured to bias the plate-shaped member toward the nozzle flow path.

12. The turbine described in claim 11, wherein the urging portion comprises: a first radially extending portion that extends radially outward and has at least a portion that abuts against the back surface of the plate-like member; an axially extending portion that has one end connected to the radially outer end of the first radially extending portion and extends away from the nozzle flow path in the axial direction; and a second radially extending portion that extends radially inward from the other end of the axially extending portion and has at least a portion that abuts against an opposing surface of another member that faces the back surface of the plate-like member across an axial gap.

13. A turbine according to any one of claims 1 to 3, wherein each of the plurality of long nozzle vanes comprises a variable nozzle vane that is rotatably provided with respect to the turbine housing.

14. A turbine according to any one of claims 1 to 3, wherein each of the plurality of elongated nozzle vanes is a fixed nozzle vane that is provided non-rotatably with respect to the turbine housing.

15. A turbo device comprising a turbine according to any one of claims 1 to 3.

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