Turbocharger gas casing and turbocharger

Abstract

To provide a supercharger gas casing capable of suppressing erosion of rotor blades in a turbine of a double-scroll structure.SOLUTION: A supercharger gas casing is provided with a scroll part in which a plurality of scroll flow passages is formed at same positions in an axial direction of a turbine. The plurality of scroll flow passages includes a first scroll flow passage. The first scroll flow passage is configured such that, in a cross section orthogonal to the axial direction of the turbine, an extension line of a line segment connecting the farthest position from a rotation axis line of the turbine in an exhaust gas inlet of the first scroll flow passage and a position of a tip of a tongue portion formed on an inner circumferential side of the first scroll flow passage does not intersect with rotor blades of the turbine.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a turbocharger gas casing and a turbocharger. [Background technology]

[0002] In turbochargers, erosion occurs when engine combustion residue collides with the turbine.

[0003] Patent Document 1 describes that in order to suppress erosion of the scroll passage of a turbine in a turbocharger, a protrusion that protrudes radially inward is provided on the passage wall of the scroll passage so as to disperse combustion residue that collides with the passage wall. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-303642 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a double-scroll turbine having a plurality of scroll passages at the same axial position of the turbine, engine combustion residues that flow into the scroll passages are likely to collide with the turbine rotor blades, which is likely to cause erosion of the turbine rotor blades. In this regard, Patent Document 1 does not disclose any knowledge on suppressing erosion of the rotor blades in a double-scroll turbine.

[0006] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a turbocharger gas casing capable of suppressing erosion of rotor blades in a turbine with a double scroll structure, and a turbocharger including the same. [Means for solving the problem]

[0007] In order to achieve the above object, a turbocharger gas casing according to at least one embodiment of the present disclosure includes: A turbocharger gas casing for a turbine of a turbocharger, comprising: a scroll portion that forms a plurality of scroll passages at the same position in the axial direction of the turbine, The plurality of scroll passages includes a first scroll passage, The first scroll passage is configured so that, in a cross section perpendicular to the axial direction of the turbine, an extension line of a line segment connecting a position at the exhaust gas inlet of the first scroll passage that is farthest from the rotation axis of the turbine and a position of the tip of a tongue portion formed on the inner side of the first scroll passage does not intersect with the rotor blades of the turbine.

[0008] In order to achieve the above object, a turbocharger according to at least one embodiment of the present disclosure includes: The turbocharger gas casing; A turbine wheel; A compressor impeller connected to the turbine wheel via a rotating shaft; Equipped with. Effect of the Invention

[0009] According to at least one embodiment of the present disclosure, there is provided a turbocharger gas casing capable of suppressing erosion of rotor blades in a turbine having a double scroll structure, and a turbocharger including the same. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a turbocharger 2 according to an embodiment of the present invention. [Diagram 2] 2 is a diagram showing a schematic cross section perpendicular to the axial direction of the turbine 6 shown in FIG. 1. [Diagram 3] 13 is a diagram showing trajectories (CFD results) of fine particles in each of the scroll passage 024 and the scroll passage 26. FIG. [Figure 4]13 is a diagram showing trajectories (CFD results) of coarse particles in each of a scroll passage 024 and a scroll passage 26. FIG. [Diagram 5] 4 is a diagram showing the trajectories of coarse particles in each of the scroll passages 24 and 26. FIG. [Figure 6] 3 is a cross-sectional view that illustrates a schematic example of the configuration of the turbine 6 illustrated in FIG. 2. [Figure 7] 7 is a schematic cross-sectional view for explaining the effect of the protrusions 40 and 42 shown in FIG. 6. FIG. [Figure 8] 3A to 3C are cross-sectional views for explaining some examples of the configuration of the turbine 6 shown in FIG. 2. [Figure 9A] 9A and 9B are schematic diagrams showing an example of the A1-A1 cross section and an example of the A2-A2 cross section in FIG. 8. [Figure 9B] 9A to 9C are schematic diagrams showing another example of the B1-B1 cross section and another example of the B2-B2 cross section in FIG. 8. [Figure 9C] 9A to 9C are schematic diagrams showing an example of a C1-C1 cross section and an example of a C2-C2 cross section in FIG. 8. [Figure 10A] 9A to 9C are schematic diagrams showing another example of the A1-A1 cross section and another example of the A2-A2 cross section in FIG. 8. [Figure 10B] 9A to 9C are schematic diagrams showing another example of the B1-B1 cross section and another example of the B2-B2 cross section in FIG. 8. [Figure 10C] 9A to 9C are schematic views showing another example of the C1-C1 cross section and another example of the C2-C2 cross section in FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, some 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 the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the invention. For example, expressions expressing relative or absolute configuration, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such a configuration, 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 indicating that things are in an equal state, such as "identical," "equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to rectangular shapes, cylindrical shapes, etc. in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions excluding the presence of other elements.

[0012] 1 is a diagram that illustrates a turbocharger 2 according to one embodiment. The turbocharger 2 may be a marine turbocharger. 1, the turbocharger 2 includes a compressor 4 and a turbine 6 which are connected to each other. A compressor impeller 8 of the compressor 4 and a turbine wheel 10 of the turbine 6 are connected via a rotating shaft 9 and are configured to rotate integrally.

[0013] When the turbine wheel 10 is driven by exhaust gas discharged from an engine (not shown), the rotation of the turbine wheel 10 is transmitted to the compressor impeller 8 via the rotary shaft 9 to rotate the compressor impeller 8, and the rotation of the compressor impeller 8 compresses air. The compressed air discharged from the compressor 4 is supplied to the engine (not shown).

[0014] Hereinafter, the axial direction of the turbine 6, i.e., the axial direction of the rotating shaft 9, will be simply referred to as the "axial direction", the circumferential direction of the turbine 6, i.e., the circumferential direction of the rotating shaft 9, will be simply referred to as the "circumferential direction", and the radial direction of the turbine 6, i.e., the radial direction of the rotating shaft 9, will be simply referred to as the "radial direction". Additionally, exhaust gas discharged from an engine (not shown) and supplied to the turbine 6 will be simply referred to as the "exhaust gas".

[0015] Fig. 2 is a diagram showing a cross section perpendicular to the axial direction of the turbine 6 shown in Fig. 1. As shown in Fig. 2, the turbine 6 includes a turbine wheel 10, a plurality of nozzle vanes 12, and a gas casing 14 (supercharger gas casing).

[0016] The turbine wheel 10 includes a hub 16 and a plurality of rotor blades 18 circumferentially spaced apart on the outer periphery of the hub 16 .

[0017] The nozzle vanes 12 are provided on the outer periphery of the turbine wheel 10 at intervals in the circumferential direction.

[0018] The gas casing 14 includes a wheel housing section 20 that houses the turbine wheel 10, a nozzle passage section 22 in which the multiple nozzle vanes 12 are arranged, and a scroll section 23 that forms multiple scroll passages 24, 26 at the same axial position. The multiple scroll passages 24, 26 include the scroll passage 24 and the scroll passage 26. In this manner, the turbine 6 is a turbine of a double scroll structure that has two scroll passages 24, 26 at the same axial position.

[0019] The wheel accommodating portion 20 extends in a cylindrical shape along the axial direction, and is configured to guide the exhaust gas passing through the turbine wheel 10 to an exhaust gas outlet of the turbine 6 .

[0020] The nozzle passage section 22 forms an annular space between the scroll section 23 and the wheel accommodating section 20. The nozzle passage section 22 connects the scroll passage 24 and the wheel accommodating section 20 in a first circumferential range (a range of 180 degrees in the illustrated exemplary embodiment), and connects the scroll passage 26 and the wheel accommodating section 20 in a second circumferential range excluding the first range (a range of 180 degrees excluding the first range in the illustrated embodiment). The exhaust gas that has passed through the scroll passage 24 or the scroll passage 26 is guided to the turbine wheel 10 by a plurality of nozzle vanes 12 arranged in the nozzle passage section 22.

[0021] The scroll passage 24 and the scroll passage 26 are arranged side by side in the circumferential direction at the same position in the axial direction. In the illustrated exemplary embodiment, the extension direction of the scroll passage 24 at the position of an inlet 24a of the scroll passage 24 (an opening on the inlet side of the scroll passage 24) and the extension direction of the scroll passage 26 at the position of an inlet 26a of the scroll passage 26 (an opening on the inlet side of the scroll passage 26) form an angle of 180 degrees or less (approximately 90 degrees in the illustrated example).

[0022] 2, in a cross section perpendicular to the axial direction of the turbine 6, the position farthest from the rotation axis O of the turbine 6 at the exhaust gas inlet 24a of the scroll passage 24 is P1, the position of the tip of the tongue portion 25 formed on the inner circumferential side of the scroll passage 24 is Q1, and an extension line obtained by linearly extending a line segment L1 connecting the positions P1 and Q1 is L1a, the scroll passage 24 is curved so that the extension line L1a does not intersect with the rotor blades 18 of the turbine 6 in a state in which the turbocharger 2 is assembled. That is, when the inside of the scroll passage 24 is viewed from the exhaust gas inlet 24a of the scroll passage 24, the scroll passage 24 is curved so that the rotor blades 18 of the turbine 6 are not visible from the inlet 24a. The position Q1 of the tip of the tongue portion 25 corresponds to the position where the downstream end of the scroll passage 26 and the scroll passage 24 are connected.

[0023] In the illustrated exemplary form, the scroll passage 24 includes a straight passage section 28 extending linearly and a scroll passage section 30 extending in a scroll shape along the circumferential direction, and when the inside of the scroll passage 24 is viewed from an exhaust gas inlet 24a formed in the straight passage section 28, the scroll passage section 30 is curved so that the rotor blades 18 of the turbine 6 are not visible from the inlet 24a.

[0024] Moreover, in a cross section perpendicular to the axial direction of the turbine 6, the scroll passage 24 is curved so that the extension line L1a does not intersect with the nozzle vanes 12. In other words, when the inside of the scroll passage 24 is viewed from an inlet 24a for exhaust gas of the scroll passage 24, the scroll passage 24 is curved so that the nozzle vanes 12 are not visible from the inlet 24a.

[0025] 2, in a cross section perpendicular to the axial direction of the turbine 6, the position farthest from the rotation axis O of the turbine 6 at the exhaust gas inlet 26a of the scroll passage 26 is P2, the position of the tip of the tongue portion 32 formed on the inner circumferential side of the scroll passage 26 is Q2, and an extension line of a line segment L2 connecting the positions P2 and Q2 is L2a, the scroll passage 26 is curved so that the extension line L2a does not intersect with the rotor blades 18 of the turbine 6 in a state in which the turbocharger 2 is assembled. That is, when the inside of the scroll passage 26 is viewed from the exhaust gas inlet 26a of the scroll passage 26, the scroll passage 26 is curved so that the rotor blades 18 of the turbine 6 are not visible from the inlet 26a. The position Q2 of the tip of the tongue portion 32 corresponds to the position where the downstream end of the scroll passage 24 and the scroll passage 26 are connected.

[0026] In the illustrated exemplary embodiment, the scroll passage 26 includes a straight passage portion 33 extending straight and a scroll passage portion 34 extending in a scroll shape along the circumferential direction, and when the inside of the scroll passage 26 is viewed from an exhaust gas inlet 26a formed in the straight passage portion 33, the scroll passage portion 34 is bent so that the rotor blades 18 of the turbine 6 are not visible from the inlet 26a. The scroll passage portion 34 extends along the outer circumferential side of the scroll passage portion 30 and connects to the nozzle passage portion 22. The downstream end of the scroll passage portion 34 passes through the inner circumferential side of the straight passage portion 28 of the scroll passage 24 and connects to the inner circumferential end of the scroll passage 24 to form the tongue portion 25 described above. The downstream end of the scroll passage portion 30 passes through the inner circumferential side of the scroll passage portion 34 of the scroll passage 26 and connects to the inner circumferential end of the scroll passage portion 34 to form the tongue portion 32 described above.

[0027] Moreover, in a cross section perpendicular to the axial direction of the turbine 6, the scroll passage 26 is curved so that the extension line L2a does not intersect with the nozzle vanes 12. In other words, when the inside of the scroll passage 26 is viewed from the exhaust gas inlet 26a of the scroll passage 26, the scroll passage 26 is curved so that the nozzle vanes 12 are not visible from the inlet 26a.

[0028] As shown in FIG. 2, in a cross section perpendicular to the axial direction of the turbine 6, the inner wall surface 36 of the scroll passage 24 (flow passage wall surface of the scroll passage 24) includes an outward surface portion 36o facing radially outward and an inward surface portion 36i facing radially inward. In the cross section shown in FIG. 2, if the position of the inlet 24a of the scroll passage 24 closest to the rotation axis O of the turbine 6 is P3, the outward surface portion 36o is a portion of the inner wall surface 36 of the scroll passage 24 that connects the position P3 and the position Q1. The outward surface portion 36o corresponds to a wall surface of the inner wall surface 36 of the scroll passage 24 that is located on the inner circumferential side of the scroll passage 24. In addition, in the cross section shown in FIG. 2, the inward surface portion 36i is a portion of the inner wall surface 36 of the scroll passage 24 that connects the position P1 and the position Q2 in the scroll passage 24. The inward surface portion 36i corresponds to a wall surface of the inner wall surface 36 of the scroll passage 24 that is located on the outer periphery side of the scroll passage 24.

[0029] Here, the surface roughness Ra (arithmetic mean roughness of the inward surface portion 36i) of the inward surface portion 36i is larger than the surface roughness Ra (arithmetic mean roughness of the outward surface portion 36o) of the outward surface portion 36o, and may be, for example, 25 μm or more.

[0030] As shown in FIG. 2, in a cross section perpendicular to the axial direction of the turbine 6, the inner wall surface 38 of the scroll passage 26 (flow passage wall surface of the scroll passage 26) includes an outward surface portion 38o facing radially outward and an inward surface portion 38i facing radially inward. In the cross section shown in FIG. 2, if the position of the inlet 26a of the scroll passage 26 closest to the rotation axis O of the turbine 6 is P4, the outward surface portion 38o is a portion of the inner wall surface 38 of the scroll passage 26 that connects the position P4 and the position Q2. The outward surface portion 38o corresponds to a wall surface of the inner wall surface 38 of the scroll passage 26 that is located on the inner circumferential side of the scroll passage 26. In addition, in the cross section shown in FIG. 2, the inward surface portion 38i is a portion of the inner wall surface 38 of the scroll passage 26 that connects the position P2 and the position Q1 in the scroll passage 26. The inward surface portion 38i corresponds to a wall surface of the inner wall surface 38 of the scroll passage 26 that is located on the outer circumferential side of the scroll passage 26.

[0031] Here, the surface roughness Ra (arithmetic mean roughness of the inward surface portion 38i) of the inward surface portion 38i is larger than the surface roughness Ra (arithmetic mean roughness of the outward surface portion 38o) of the outward surface portion 38o, and may be, for example, 25 μm or more.

[0032] Here, the effects achieved by the gas casing 14 shown in FIG. 2 will be described in comparison with the configuration shown in FIG.

[0033] In the case where the turbine 6 has a scroll passage 024 having a shape shown in Fig. 3 (the scroll passage 024 in which an inlet 024a of the scroll passage 024 is linearly connected to the rotor blade 18 such that the extension line L1a intersects with the rotor blade 18 of the turbine 6), fine particles of several µm or less of the combustion residue contained in the exhaust gas of an engine (not shown) follow the flow of the exhaust gas, flow into the pressure surface (ventral surface) of the rotor blade 18, and pass between the rotor blades 18, as shown in Fig. 3. On the other hand, in the configuration shown in Fig. 3, coarse particles of 10 µm or more of the combustion residue contained in the exhaust gas of the engine do not follow the flow of the exhaust gas due to their large inertia, and collide with the negative pressure surface (back surface) of the rotor blade 18 of the turbine wheel 10, as shown in Fig. 4, causing erosion of the rotor blade 18.

[0034] In contrast, according to the gas casing 14 shown in Fig. 2, the scroll passage 24 is bent so that the extension line L1a does not intersect with the rotor blades 18 of the turbine 6, and therefore, the coarse particles contained in the exhaust gas collide with the inner wall surface 36 of the scroll passage 24 before colliding with the rotor blades 18, as shown by the arrow a1 in Fig. 5. In addition, according to the knowledge of the inventors of the present application, it is considered that the effect of the coarse particles that collide with the inner wall surface 36 of the scroll passage 24 on the erosion of the rotor blades 18 is limited even if they subsequently flow downstream. Therefore, it is possible to suppress the direct collision of the coarse particles in the exhaust gas that has flowed into the scroll passage 24 with the rotor blades 18 of the turbine 6, and suppress the erosion of the rotor blades 18 of the turbine 6.

[0035] In addition, since the scroll passage 24 is bent so that the extension line L1a does not intersect with the nozzle vanes 12 of the turbine 6, coarse particles contained in the exhaust gas collide with the inner wall surface 36 of the scroll passage 24 before passing between adjacent nozzle vanes 12, as shown by arrow a1 in Fig. 5. This prevents coarse particles contained in the exhaust gas from being guided by the nozzle vanes 12 to the moving blades 18 of the turbine 6, and effectively suppresses erosion of the moving blades 18 of the turbine 6.

[0036] In addition, since the surface roughness Ra of the inward surface portion 36i is larger than the surface roughness Ra of the outward surface portion 36o, particles that collide with the inward surface portion 36i are likely to be broken down into smaller particles due to friction with the inward surface portion 36i as they flow downstream. In addition, compared to a case in which the surface roughness Ra of the inner wall surface 36 of the scroll passage 24 is uniformly increased, an increase in pressure loss in the scroll passage 24 can be suppressed. For this reason, an increase in pressure loss in the scroll passage 24 can be suppressed while effectively suppressing erosion of the rotor blades 18 of the turbine 6 caused by engine combustion residues.

[0037] Furthermore, according to the findings of the present inventors, the diameter of particles that have a significant effect on the erosion of the rotor blades 18 is thought to be about 50 μm, and by setting the surface roughness Ra of the inward surface portion 36i to 25 μm or more, the effect of particle refinement due to friction with the inward surface portion 36i can be enhanced, thereby effectively suppressing erosion of the rotor blades 18 of the turbine 6.

[0038] 2, the scroll passage 26 is bent so that the extension line L2a does not intersect with the rotor blades 18 of the turbine 6, and therefore, the coarse particles contained in the exhaust gas collide with the inner wall surface 38 of the scroll passage 26 before colliding with the rotor blades 18, as shown by the arrow a2 in FIG. 5. According to the findings of the present inventors, the effect of the coarse particles that collide with the inner wall surface 38 of the scroll passage 26 on the erosion of the rotor blades 18 is considered to be limited even if they subsequently flow downstream. For this reason, it is possible to suppress the direct collision of the coarse particles in the exhaust gas that has flowed into the scroll passage 26 with the rotor blades 18 of the turbine 6, thereby suppressing the erosion of the rotor blades 18 of the turbine 6.

[0039] In addition, since the scroll passage 24 is bent so that the extension line L2a does not intersect with the nozzle vanes 12 of the turbine 6, coarse particles contained in the exhaust gas collide with the inner wall surface 38 of the scroll passage 26 before passing between adjacent nozzle vanes 12, as shown by arrow a2 in Fig. 5. This prevents coarse particles contained in the exhaust gas from being guided by the nozzle vanes 12 to the moving blades 18 of the turbine 6, and effectively suppresses erosion of the moving blades 18 of the turbine 6.

[0040] In addition, since the surface roughness Ra of the inward surface portion 38i is larger than the surface roughness Ra of the outward surface portion 38o, particles that collide with the inward surface portion 38i are likely to be broken down into smaller particles due to friction with the inward surface portion 38i as they flow downstream. In addition, compared to a case in which the surface roughness Ra of the inner wall surface 38 of the scroll passage 26 is made uniformly large, an increase in pressure loss in the scroll passage 26 can be suppressed. For this reason, an increase in pressure loss in the scroll passage 26 can be suppressed while effectively suppressing erosion of the rotor blades 18 of the turbine 6 caused by engine combustion residues.

[0041] Furthermore, according to the findings of the present inventors, the diameter of particles that have a significant effect on the erosion of the rotor blades 18 is thought to be about 50 μm, and by setting the surface roughness Ra of the inward surface portion 38i to 25 μm or more, the effect of particle refinement due to friction with the inward surface portion 38i can be enhanced, thereby effectively suppressing erosion of the rotor blades 18 of the turbine 6.

[0042] In some embodiments, the outward surface portion 36o of the scroll passage 24 may include a protrusion 40 protruding radially outward, as shown in Fig. 6 for example. That is, the outward surface portion 36o of the scroll passage 24 may include a protrusion 40 protruding toward the inward surface portion 36i. In the illustrated example, the protrusion 40 is formed in a triangular shape in a cross section perpendicular to the axial direction of the turbine 6. In addition, the protrusion 40 is located upstream of a position Q1 of the tip of the tongue portion 25.

[0043] In addition, if the flow passage width in the direction perpendicular to the axial direction at the position of the protrusion 40 in the scroll flow passage 24 is W1, the protrusion 40 has a height h1 that is 20% or more of the flow passage width W1. In the illustrated example, the flow passage width W1 is the flow passage width in the direction perpendicular to the axial direction at the position of the tip of the protrusion 40 in the scroll flow passage 24.

[0044] By providing the protrusions 40 on the outward surface portion 36o in this manner, the particles can be collided with a more upstream position on the inner wall surface 36 of the scroll passage 24 as shown by the arrow a1 in Fig. 7, as compared to a case in which the protrusions 40 are not provided, and the particles can be made finer by increasing the time and distance during which the particles are subjected to frictional force from the inner wall surface 36. Therefore, erosion of the rotor blades 18 can be effectively suppressed. In addition, by making the height h1 of the protrusions 40 20% or more of the passage width W1, the effect of promoting the fine particle size can be enhanced, as compared to a case in which the height h1 is less than 20% of the passage width W1.

[0045] In some embodiments, the outward surface portion 38o of the scroll passage 26 may include a protrusion 42 protruding radially outward, as shown in Fig. 6 for example. That is, the outward surface portion 38o of the scroll passage 26 may include a protrusion 42 protruding toward the inward surface portion 38i. In the illustrated example, the protrusion 42 is formed in a triangular shape in a cross section perpendicular to the axial direction of the turbine 6. The protrusion 42 is located upstream of a position Q2 of the tip of the tongue portion 32.

[0046] Furthermore, if the flow passage width in the direction perpendicular to the axial direction at the position of the protrusion 42 in the scroll flow passage 26 is W2, the protrusion 42 has a height h2 that is 20% or more of the flow passage width W2. In the illustrated example, the flow passage width W2 is the flow passage width in the direction perpendicular to the axial direction at the position of the tip of the protrusion 42 in the scroll flow passage 26.

[0047] By providing the protrusions 42 on the outward surface portion 38o in this manner, the particles can be collided with a more upstream position on the inner wall surface 38 of the scroll passage 26 as shown by the arrow a2 in Fig. 7, as compared to a case in which the protrusions 42 are not provided, and the particles can be made finer by increasing the time and distance during which the particles are subjected to frictional force from the inner wall surface 38. Therefore, erosion of the rotor blades 18 can be effectively suppressed. In addition, by making the height h2 of the protrusions 42 20% or more of the passage width W2, the effect of promoting the fine particle size can be enhanced, as compared to a case in which the height h2 is less than 20% of the passage width W2.

[0048] 9A is a schematic diagram showing an example of the A1-A1 cross section and an example of the A2-A2 cross section shown in FIG. 8 for the turbine 6 shown in FIG. 2. FIG. 9B is a schematic diagram showing an example of the B1-B1 cross section and an example of the B2-B2 cross section shown in FIG. 8 for the turbine 6 shown in FIG. 2. FIG. 9C is a schematic diagram showing an example of the C1-C1 cross section and an example of the C2-C2 cross section shown in FIG. 8 for the turbine 6 shown in FIG. 2. Each of the A1-A1 cross section, the B1-B1 cross section, and the C1-C1 cross section is a schematic diagram showing a flow passage cross section perpendicular to the extension direction of the scroll flow passage 24 in the scroll flow passage 24. Each of the A2-A2 cross section, the B2-B2 cross section, and the C2-C2 cross section is a schematic diagram showing a flow passage cross section perpendicular to the extension direction of the scroll flow passage 26 in the scroll flow passage 26.

[0049] In some embodiments, as shown in Fig. 9A, the straight passage portion 28 of the scroll passage 24 includes a circular passage cross section. Also, as shown in Fig. 9B and Fig. 9C, the scroll passage portion 30 of the scroll passage 24 includes a passage cross section in which a passage height H in the axial direction is greater than a passage width W in a direction perpendicular to the axial direction (a passage width direction perpendicular to both the axial direction and the direction in which the scroll passage 24 extends).

[0050] 9B and 9C, the scroll passage section 30 of the scroll passage 24 includes an elliptical passage cross section such that a passage height H in the axial direction is greater than a passage width W in a direction perpendicular to the axial direction. In the illustrated example, the major axis of the elliptical passage cross section extends along the axial direction, and the minor axis of the elliptical passage cross section extends along a direction perpendicular to the axial direction. The major axis of the elliptical passage cross section may extend parallel to the axial direction, and the minor axis of the elliptical passage cross section may extend in a direction perpendicular to the axial direction.

[0051] In addition, the flow passage cross section of the scroll flow passage 24 may be formed into a circular shape over the entire section of the straight flow passage section 28, and may be formed into an elliptical shape over the entire section of the scroll flow passage section 30 so that the flow passage height H in the axial direction is greater than the flow passage width W in the direction perpendicular to the axial direction.

[0052] As shown in Figures 9B and 9C, the scroll flow passage 24 may be formed such that the ratio H / W of the flow passage height H in the axial direction to the flow passage width W in a direction perpendicular to the axial direction increases toward the downstream side of the scroll flow passage section 30.

[0053] As described above, by making the axial flow passage height H greater than the flow passage width W in the flow passage cross section of the scroll flow passage section 30 in the scroll flow passage 24, the contribution of the portion on the inner wall surface 36 of the scroll flow passage 24 where the particles collide is increased, promoting particle refinement due to friction between the inner wall surface 36 of the scroll flow passage 24 and the particles, and effectively reducing erosion of the rotor blades 18 of the turbine 6.

[0054] Furthermore, by forming the scroll passage 24 so that the ratio H / W of the passage height H in the axial direction to the passage width W in the direction perpendicular to the axial direction increases toward the downstream side of the scroll passage section 30, it is possible to promote particle refinement due to friction between the particles and the inner wall surface 36 of the scroll passage 24 while suppressing an increase in pressure loss due to a change in the passage shape.

[0055] In some embodiments, as shown in FIG. 9A, the straight passage section 33 of the scroll passage 26 includes a circular passage cross section. Also, as shown in FIG. 9B and FIG. 9C, the scroll passage section 34 of the scroll passage 26 includes a passage cross section in which the passage height H in the axial direction is larger than the passage width W in a direction perpendicular to the axial direction (a passage width direction perpendicular to each of the axial direction and the direction in which the scroll passage 26 extends). In the example shown in FIG. 9B and FIG. 9C, the scroll passage section 34 of the scroll passage 26 includes an elliptical passage cross section such that the passage height H in the axial direction is larger than the passage width W in a direction perpendicular to the axial direction. In the illustrated example, the major axis of the elliptical passage cross section extends along the axial direction, and the minor axis of the elliptical passage cross section extends along a direction perpendicular to the axial direction. The major axis of the elliptical passage cross section may extend parallel to the axial direction, and the minor axis of the elliptical passage cross section may extend in a direction perpendicular to the axial direction.

[0056] The flow passage cross section of the scroll flow passage 26 may be formed into a circular shape over the entire section of the straight flow passage section 33 as shown in FIG. 9A, or may be formed into an elliptical shape over the entire section of the scroll flow passage section 34 so that the flow passage height H in the axial direction is larger than the flow passage width W in the direction perpendicular to the axial direction as shown in FIGS. 9B and 9C.

[0057] As shown in Figures 9B and 9C, the scroll flow passage 26 may be formed such that the ratio H / W of the flow passage height H in the axial direction to the flow passage width W in a direction perpendicular to the axial direction increases toward the downstream side of the scroll flow passage section 34.

[0058] As described above, by making the axial flow passage height H greater than the flow passage width W in the flow passage cross section of the scroll flow passage section 34 in the scroll flow passage 26, the contribution of the portion on the inner wall surface 38 of the scroll flow passage 26 with which the particles collide is increased, promoting particle refinement due to friction between the inner wall surface 38 of the scroll flow passage 26 and the particles, and effectively reducing erosion of the rotor blades 18 of the turbine 6.

[0059] Furthermore, by forming the scroll passage 26 so that the ratio H / W of the passage height H in the axial direction to the passage width W in the direction perpendicular to the axial direction increases toward the downstream side of the scroll passage section 34, it is possible to promote particle refinement due to friction between the particles and the inner wall surface 38 of the scroll passage 26 while suppressing an increase in pressure loss due to a change in the passage shape.

[0060] FIG. 10A is a schematic diagram showing another example of the A1-A1 cross section and another example of the A2-A2 cross section shown in FIG. 8 for the turbine 6 shown in FIG. 2. FIG. 10B is a schematic diagram showing another example of the B1-B1 cross section and another example of the B2-B2 cross section shown in FIG. 8 for the turbine 6 shown in FIG. 2. FIG. 10C is a schematic diagram showing another example of the C1-C1 cross section and another example of the C2-C2 cross section shown in FIG. 8 for the turbine 6 shown in FIG. 2. Each of the A1-A1 cross section, the B1-B1 cross section, and the C1-C1 cross section is a schematic diagram showing a flow passage cross section perpendicular to the extension direction of the scroll flow passage 24 in the scroll flow passage 24. Each of the A2-A2 cross section, the B2-B2 cross section, and the C2-C2 cross section is a schematic diagram showing a flow passage cross section perpendicular to the extension direction of the scroll flow passage 26 in the scroll flow passage 26.

[0061] In some embodiments, as shown in FIG. 10A, the linear passage section 28 of the scroll passage 24 includes a circular passage cross section. Also, as shown in FIG. 10B and FIG. 10C, the scroll passage section 30 of the scroll passage 24 includes a passage cross section in which the passage height H in the axial direction is larger than the passage width W in a direction perpendicular to the axial direction (directions perpendicular to both the axial direction and the direction in which the scroll passage 24 extends). In the example shown in FIG. 10B and FIG. 10C, the scroll passage section 30 of the scroll passage 24 includes a rectangular (rectangular) passage cross section so that the passage height H in the axial direction is larger than the passage width W in a direction perpendicular to the axial direction. In the illustrated example, the long side of the rectangular passage cross section extends along the axial direction, and the short side of the rectangular passage cross section extends along a direction perpendicular to the axial direction. The long side of the rectangular passage cross section may extend parallel to the axial direction, and the short side of the rectangular passage cross section may extend in a direction perpendicular to the axial direction.

[0062] In addition, the flow passage cross section of the scroll flow passage 24 may be formed into a circular shape over the entire section of the straight flow passage section 28 as shown in FIG. 10A, and may be formed so that the flow passage height H in the axial direction is larger than the flow passage width W in the direction perpendicular to the axial direction over the entire section of the scroll flow passage section 30 as shown in FIGS. 10B and 10C.

[0063] As shown in FIGS. 10B and 10C, the scroll flow passage 24 may be formed such that the ratio H / W of the flow passage height H in the axial direction to the flow passage width W in the direction perpendicular to the axial direction increases toward the downstream side of the scroll flow passage section 30.

[0064] As described above, by making the axial flow passage height H greater than the flow passage width W in the flow passage cross section of the scroll flow passage section 30 in the scroll flow passage 24, the contribution of the portion on the inner wall surface 36 of the scroll flow passage 24 where the particles collide is increased, promoting particle refinement due to friction between the inner wall surface 36 of the scroll flow passage 24 and the particles, and effectively reducing erosion of the rotor blades 18 of the turbine 6.

[0065] Furthermore, by forming the scroll passage 24 so that the ratio H / W of the passage height H in the axial direction to the passage width W in the direction perpendicular to the axial direction increases toward the downstream side of the scroll passage section 30, it is possible to promote particle refinement due to friction between the particles and the inner wall surface 36 of the scroll passage 24 while suppressing an increase in pressure loss due to a change in the passage shape.

[0066] In some embodiments, as shown in FIG. 10A, the straight passage section 33 of the scroll passage 26 includes a circular passage cross section. Also, as shown in FIG. 10B and FIG. 10C, the scroll passage section 34 of the scroll passage 26 includes a passage cross section in which the passage height h in the axial direction is larger than the passage width W in a direction perpendicular to the axial direction (directions perpendicular to both the axial direction and the direction in which the scroll passage 26 extends). In the example shown in FIG. 10B and FIG. 10C, the scroll passage section 34 of the scroll passage 26 includes a rectangular passage cross section such that the passage height h in the axial direction is larger than the passage width W in a direction perpendicular to the axial direction. In the illustrated example, the long side of the rectangular passage cross section extends along the axial direction, and the short side of the rectangular passage cross section extends along a direction perpendicular to the axial direction. The long side of the rectangular passage cross section may extend parallel to the axial direction, and the short side of the rectangular passage cross section may extend in a direction perpendicular to the axial direction.

[0067] The cross section of the scroll flow passage 26 may be circular over the entire section of the straight flow passage section 33 as shown in FIG. 10A, or may be rectangular over the entire section of the scroll flow passage section 34 such that the flow passage height h in the axial direction is greater than the flow passage width W in the direction perpendicular to the axial direction as shown in FIGS. 10B and 10C.

[0068] As shown in FIGS. 10B and 10C, the scroll flow passage 26 may be formed such that the ratio H / W of the flow passage height H in the axial direction to the flow passage width W in the direction perpendicular to the axial direction increases toward the downstream side of the scroll flow passage section 34.

[0069] As described above, by making the axial flow passage height H greater than the flow passage width W in the flow passage cross section of the scroll flow passage section 34 in the scroll flow passage 26, the contribution of the portion on the inner wall surface 38 of the scroll flow passage 26 with which the particles collide is increased, promoting particle refinement due to friction between the inner wall surface 38 of the scroll flow passage 26 and the particles, and effectively reducing erosion of the rotor blades 18 of the turbine 6.

[0070] Furthermore, by forming the scroll passage 26 so that the ratio H / W of the passage height H in the axial direction to the passage width W in the direction perpendicular to the axial direction increases toward the downstream side of the scroll passage section 34, it is possible to promote particle refinement due to friction between the particles and the inner wall surface 38 of the scroll passage 26 while suppressing an increase in pressure loss due to a change in the passage shape.

[0071] The present disclosure is not limited to the above-described embodiments, and includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0072] The contents described in each of the above embodiments can be understood, for example, as follows.

[0073] (1) A turbocharger gas casing according to at least one embodiment of the present disclosure, A turbocharger gas casing (e.g., the above-mentioned gas casing 14) of a turbine (e.g., the above-mentioned turbine 6) of a turbocharger (e.g., the above-mentioned turbocharger 2), A scroll section (e.g., the above-mentioned scroll section 23) is provided at the same position in the axial direction of the turbine to form a plurality of scroll passages (e.g., the above-mentioned scroll passage 24 and scroll passage 26), The plurality of scroll passages includes a first scroll passage (e.g., the scroll passage 24 or the scroll passage 26 described above), The first scroll passage is configured so that, in a cross section perpendicular to the axial direction of the turbine, an extension line (for example, the above-mentioned extension line L1a or L2a) of a line segment connecting a position at the exhaust gas inlet of the first scroll passage (for example, the above-mentioned inlet 24a or 26a) farthest from the rotation axis of the turbine (for example, the above-mentioned position P1 or P2) and the position of the tip of a tongue portion formed on the inner side of the first scroll passage (for example, the above-mentioned position Q1 or Q2) does not intersect with a rotor blade of the turbine (for example, the above-mentioned rotor blade 18).

[0074] According to the turbocharger gas casing described in (1) above, the first scroll passage is configured so that the extension line does not intersect with the turbine rotor blades, so that coarse particles contained in the exhaust gas collide with the inner wall surface of the first scroll passage before colliding with the rotor blades. In addition, according to the findings of the present inventors, it is considered that the effect of coarse particles that collide with the inner wall surface of the first scroll passage on the erosion of the rotor blades is limited even if they subsequently flow downstream. Therefore, it is possible to suppress the direct collision of coarse particles contained in the exhaust gas that has flowed into the first scroll passage with the turbine rotor blades, thereby suppressing the erosion of the turbine rotor blades.

[0075] (2) In some embodiments, in the turbocharger gas casing described in (1) above, The first scroll passage is configured so that the extension line does not intersect with a nozzle vane (for example, the above-mentioned nozzle vane 12) that guides the flow to the rotor blades in the turbine.

[0076] According to the turbocharger gas casing described in (2) above, coarse particles contained in the exhaust gas collide with the inner wall surface of the first scroll passage before passing between adjacent nozzle vanes, which prevents the coarse particles contained in the exhaust gas from being guided to the turbine rotor blades by the nozzle vanes, and effectively prevents erosion of the turbine rotor blades.

[0077] (3) In some embodiments, in the turbocharger gas casing described in (1) or (2), The inner wall surface of the first scroll passage (for example, the inner wall surface 36 or 38 described above) An outward surface portion (e.g., the above-mentioned outward surface portion 36o or 38o) facing outward in the radial direction of the turbine; An inward surface portion (e.g., the inward surface portion 36i or 38i described above) facing inward in the radial direction of the turbine and having a surface roughness Ra greater than that of the outward surface portion; Includes.

[0078] According to the turbocharger gas casing described in (3) above, since the surface roughness Ra of the inward surface portion is larger than the surface roughness of the outward surface portion, particles colliding with the inward surface portion are likely to be broken down into smaller particles as they flow downstream due to friction with the inward surface portion. Also, compared to a case in which the surface roughness of the inner wall surface of the first scroll passage is made larger overall, an increase in pressure loss in the first scroll passage can be suppressed. Therefore, an increase in pressure loss in the first scroll passage can be suppressed while effectively suppressing erosion of the turbine rotor blades caused by engine combustion residues.

[0079] (4) In some embodiments, in the turbocharger gas casing described in (3) above, The surface roughness Ra of the inward surface portion is 25 μm or more.

[0080] According to the findings of the present inventors, the diameter of particles that have a significant effect on the erosion of the rotor blades is believed to be about 50 μm. By setting the surface roughness Ra of the inward surface portion to 25 μm or more as described in (4) above, the effect of particle refinement due to friction with the inward surface portion can be enhanced, thereby making it possible to effectively suppress erosion of the turbine rotor blades.

[0081] (5) In some embodiments, in the turbocharger gas casing according to any one of (1) to (4), The inner wall surface of the first scroll passage (for example, the inner wall surface 36 or 38 described above) An outward surface portion (e.g., the above-mentioned outward surface portion 36o or 38o) facing outward in the radial direction of the turbine; An inward surface portion (e.g., the inward surface portion 36i or 38i) facing inward in the radial direction of the turbine; Including, The outward surface portion includes a protrusion (for example, the above-mentioned protrusion 40 or 42) that protrudes outward in the radial direction.

[0082] According to the turbocharger gas casing described in (5) above, compared to a case without the protrusions, the particles can be collided at a more upstream position on the inner wall surface of the first scroll passage, and the time and distance during which the particles are subjected to frictional force from the inner wall surface can be increased, thereby facilitating the particle refinement, thereby effectively suppressing the erosion of the rotor blades.

[0083] (6) In some embodiments, in the turbocharger gas casing described in (5) above, The protrusion is located upstream of the tip of the tongue.

[0084] According to the turbocharger gas casing described in (6) above, compared to a case where there is no protrusion upstream of the tip of the tongue, the particles can be collided at a more upstream position on the inner wall surface of the first scroll passage, and the time and distance during which the particles are subjected to frictional force from the inner wall surface can be increased, thereby facilitating the particle refinement. Therefore, the erosion of the moving blades can be effectively suppressed.

[0085] (7) In some embodiments, in the turbocharger gas casing described in (5) or (6), The protrusion has a height (for example, the above-mentioned height h1 or h2) that is 20% or more of the passage width (for example, the above-mentioned passage width W1 or W2) in the first scroll passage in a direction perpendicular to the axial direction.

[0086] According to the turbocharger gas casing described in (7) above, the effect of promoting particle refinement can be enhanced compared to a case in which the height of the protrusion is less than 20% of the flow passage width in the direction perpendicular to the axial direction in the first scroll flow passage.

[0087] (8) In some embodiments, in the turbocharger gas casing according to any one of (1) to (7), The first scroll passage includes a passage cross section in which a passage height in the axial direction (eg, the above-mentioned passage height H) is greater than a passage width in a direction perpendicular to the axial direction (eg, the above-mentioned passage width W).

[0088] According to the turbocharger gas casing described in (8) above, by making the axial passage height larger than the passage width in the passage cross section of the first scroll passage, the contribution of the portion on the inner wall surface of the first scroll passage where particles collide is increased, promoting the break-up of particles due to friction between the inner wall surface of the first scroll passage and the particles, and making it possible to effectively reduce erosion of the turbine rotor blades.

[0089] (9) In some embodiments, in the turbocharger gas casing described in (8) above, The cross-sectional shape of the flow passage is elliptical or rectangular.

[0090] According to the turbocharger gas casing described in (9) above, the effect described in (8) above can be obtained with a simple shape.

[0091] (10) A turbocharger according to at least one embodiment of the present disclosure, A turbocharger gas casing according to any one of (1) to (9) above; A turbine wheel (e.g., the turbine wheel 10 described above); A compressor impeller (for example, the above-mentioned compressor impeller 8) connected to the turbine wheel via a rotating shaft; Equipped with.

[0092] According to the turbocharger described in (10) above, since it is equipped with the turbocharger casing described in any one of (1) to (9) above, it is possible to suppress erosion of the turbine blades and improve the reliability of the turbocharger. [Explanation of symbols]

[0093] 2. Turbocharger 4. Compressor 6. Turbine 8 Compressor impeller 9 Rotation Axis 10 Turbine Wheel 12 Nozzle vanes 14 Gas casing 16 Hub 18 Moving blade 20 Wheel storage section 22 Nozzle passage 23 Scroll section 24 First scroll passage 24a Entrance 25 Tongue 26 Second scroll passage 26a Entrance 28 Straight channel section 30 Scroll flow passage section 32 Tongue 33 Straight channel section 34 Scroll flow passage section 36 Inner Wall Surface 36i Inward facing part 36o outward facing part 38 Inner Wall 38i Inward facing section 38o outward facing part 40 Protrusion 42 Protrusion

Claims

1. A turbocharger gas casing for a turbine of a turbocharger, comprising: a scroll portion that forms a plurality of scroll passages at the same position in the axial direction of the turbine, the plurality of scroll passages includes a first scroll passage, the first scroll passage is configured such that, in a cross section perpendicular to the axial direction of the turbine, an extension line of a line segment connecting a position at an exhaust gas inlet of the first scroll passage farthest from a rotation axis of the turbine and a position of a tip of a tongue portion formed on an inner circumferential side of the first scroll passage does not intersect with a rotor blade of the turbine; the first scroll passage is configured such that a nozzle vane that guides a flow to the rotor blade in the turbine does not intersect with the extension line; The first scroll passage includes a first scroll passage portion extending along a circumferential direction of the turbine, The first scroll flow passage is formed such that a ratio H / W of a flow passage height H in the axial direction to a flow passage width W in a direction perpendicular to the axial direction increases toward the downstream side of the first scroll flow passage portion. Supercharger gas casing.

2. A turbocharger gas casing for a turbine of a turbocharger, comprising: a scroll portion that forms a plurality of scroll passages at the same position in the axial direction of the turbine, the plurality of scroll passages includes a first scroll passage, the first scroll passage is configured such that, in a cross section perpendicular to the axial direction of the turbine, an extension line of a line segment connecting a position at an exhaust gas inlet of the first scroll passage farthest from a rotation axis of the turbine and a position of a tip of a tongue portion formed on an inner circumferential side of the first scroll passage does not intersect with a rotor blade of the turbine; The inner wall surface of the first scroll passage is an outward surface portion facing outward in a radial direction of the turbine; an inward surface portion facing inward in a radial direction of the turbine, the inward surface portion having a surface roughness Ra greater than that of the outward surface portion; including a turbocharger gas casing.

3. 3. The turbocharger gas casing according to claim 2, wherein the inward surface portion has a surface roughness Ra of 25 μm or more.

4. The inner wall surface of the first scroll passage is an outward surface portion facing outward in a radial direction of the turbine; an inward surface portion facing inward in a radial direction of the turbine; Including, The turbocharger gas casing according to claim 1 , wherein the outward surface portion includes a protrusion that protrudes outward in the radial direction.

5. A turbocharger gas casing for a turbine of a turbocharger, comprising: a scroll portion that forms a plurality of scroll passages at the same position in the axial direction of the turbine, the plurality of scroll passages includes a first scroll passage, the first scroll passage is configured such that, in a cross section perpendicular to the axial direction of the turbine, an extension line of a line segment connecting a position at an exhaust gas inlet of the first scroll passage farthest from a rotation axis of the turbine and a position of a tip of a tongue portion formed on an inner circumferential side of the first scroll passage does not intersect with a rotor blade of the turbine; The inner wall surface of the first scroll passage is an outward surface portion facing outward in a radial direction of the turbine; an inward surface portion facing inward in a radial direction of the turbine; Including, The outward surface portion includes a protrusion portion protruding outward in the radial direction, The protrusion is located upstream of the tip of the tongue.

6. 6. The turbocharger gas casing according to claim 4, wherein the protrusion has a height that is 20% or more of a passage width of the first scroll passage in a direction perpendicular to the axial direction.

7. The turbocharger gas casing according to claim 1 , wherein the first scroll passage includes a passage cross section in which a passage height in the axial direction is greater than a passage height in a direction perpendicular to the axial direction.

8. The turbocharger gas casing according to claim 7 , wherein the cross-sectional shape of the flow passage is elliptical or rectangular.

9. A turbocharger gas casing according to any one of claims 1 to 8; A turbine wheel; A compressor impeller connected to the turbine wheel via a rotating shaft; A turbocharger.

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