Turbine and turbocharger having the same

Abstract

The turbine comprises: an impeller having a hub provided with a plurality of moving blades and capable of rotating; and a tubular member, wherein the tubular member is formed with a diffuser located on the downstream side of the impeller, and on the inner surface of the tubular member, at a position closer to the inlet end of the tubular member than the outlet end of the tubular member, a plurality of protrusions protruding radially inwardly of the tubular member are formed, and the plurality of protrusions are arranged along the circumferential direction of the inner surface with intervals between adjacent protrusions.

Description

Technical Field

[0001] The present disclosure relates to a turbine and a turbocharger including the turbine. Background Art

[0002] The turbocharger installed in the automobile operates in a wide range from low speed (small flow) to high speed (large flow), and therefore, the performance at each operating point is required to be improved. For example, in Patent Documents 1 and 2, stationary vanes are arranged on the shroud side downstream of the turbine rotor blades to control the flow on the shroud side, thereby achieving improved turbine efficiency.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 9-264106

[0006] Patent Document 2: Japanese Patent Application Publication No. 2012-177357 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, when stationary blades are provided downstream of the turbine moving blades, although the efficiency of the turbine can be improved at a certain operating point, losses may occur at other operating points. In addition, the provision of such stationary blades may also lead to deterioration of manufacturability and cost. On the other hand, on the large flow side, the performance of the diffuser constituting the turbine is greatly related to the performance of the turbine. Therefore, according to the characteristics of each operating point, the shape of the diffuser that can improve the performance of the turbine moving blades is required.

[0009] In view of the above circumstances, an object of at least one embodiment of the present disclosure is to provide a turbine with improved performance and a turbocharger including the turbine.

[0010] Solutions to Solve Problems

[0011] In order to achieve the above-mentioned purpose, the turbine disclosed in the present invention comprises: an impeller having a hub provided with a plurality of moving blades and capable of rotating; and a tubular component, the tubular component forming a diffuser located on the downstream side of the impeller, and on the inner surface of the tubular component, at a position closer to the inlet end of the tubular component than the outlet end of the tubular component, a plurality of protrusions protruding radially inwardly of the tubular component are formed, and the plurality of protrusions are arranged along the circumferential direction of the inner surface in a manner with intervals between adjacent protrusions.

[0012] Effects of the Invention

[0013] The fluid passing through the moving blades usually contains a swirling flow, so the flow of the fluid approaches the shroud side and generates a countercurrent vortex on its radial inner side. In contrast, according to the turbine disclosed in the present invention, a plurality of protrusions protruding radially inwardly of the tubular member are formed, and flow separation occurs between adjacent protrusions. Through this separation, the flow of the fluid close to the shroud side is shifted radially inward as a whole. By being attracted by the flow of the fluid in such a diffuser, the flow velocity of the flow between adjacent moving blades and near the center of the span direction of the moving blade increases. As a result, the flow velocity difference of the fluid between the inlet and outlet of the moving blade increases, that is, the static pressure difference between the inlet and outlet of the moving blade increases, and the torque applied to the blade surface of the moving blade increases, thereby improving the performance of the turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the structure of a turbocharger according to one embodiment of the present disclosure.

[0015] Figure 2 It is a schematic cross-sectional view of a turbine according to an embodiment of the present disclosure.

[0016] Figure 3 This is a perspective view of a cylindrical member of a turbine according to an embodiment of the present disclosure.

[0017] Figure 4 This is a perspective view of a modified example of the cylindrical member of the turbine according to the embodiment of the present disclosure.

[0018] Figure 5 It is a schematic cross-sectional view of a turbine according to an embodiment of the present disclosure.

[0019] Figure 6 This is a diagram for explaining the flow of exhaust gas in a diffuser in a conventional turbine.

[0020] Figure 7 It is used to illustrate the Figure 2 Diagram of the flow of exhaust gas in the cross section of line VII-VII.

[0021] Figure 8 This is a diagram for explaining the flow of exhaust gas in a diffuser in a turbine according to an embodiment of the present disclosure.

[0022] Fig. 9 This is a diagram showing the flow of exhaust gas between adjacent rotor blades in the turbine according to the embodiment of the present disclosure. DETAILED DESCRIPTION

[0023] Hereinafter, a turbine according to an embodiment of the present disclosure will be described based on the drawings. This embodiment represents one mode of the present disclosure and does not limit the present disclosure, and can be arbitrarily modified within the scope of the technical concept of the present disclosure.

[0024] <Structure of a turbocharger according to one embodiment of the present disclosure>

[0025] like Figure 1 As shown, a turbocharger 1 according to an embodiment of the present disclosure includes a turbine 3 driven by exhaust gas discharged from an internal combustion engine 2, and a compressor 5 driven by the rotation of the turbine 3 transmitted via a drive shaft 4. The compressor 5 compresses air and supplies the compressed air to the internal combustion engine 2.

[0026] <Structure of Turbine According to One Embodiment of the Present Disclosure>

[0027] like Figure 2 As shown, the turbine 3 includes: a rotatable impeller 10; and a tubular member 20, the tubular member 20 having a diffuser 15 formed therein and located downstream of the impeller 10 in the direction of the flow EG of the exhaust gas in the turbine 3. The impeller 10 includes a hub 11 and a plurality of moving blades 12 ( Figure 2 Only one moving lobe is depicted).

[0028] The tubular member 20 includes an inlet end 21 and an outlet end 22. On the inner surface 20a of the tubular member 20, a plurality of protrusions 23 are formed at a position closer to the inlet end 21 than the outlet end 22, preferably near the inlet end 21, protruding toward the radial inner side of the tubular member 20. Figure 3 As shown, near the inlet end 21 of the tubular member 20, the recessed portion 20c of the outer surface 20b corresponds to the protrusion 23 formed on the inner surface 20a, and the plurality of protrusions 23 are arranged along the circumferential direction of the inner surface 20a with intervals between adjacent protrusions 23, 23.

[0029] like Figure 2 As shown in FIG. 1 , the protrusion 23 has a shape including a first end 23a on the inlet end 21 side and a second end 23b on the outlet end 22 side and extending from the first end 23a to the second end 23b. The protrusion 23 is configured such that the first end 23a and the second end 23b are located at the same position in the circumferential direction of the inner surface 20a. However, this is not limited to this embodiment. For example, Figure 4 As shown, the protrusion 23 may also be configured such that the second end 23b is located closer to the impeller 10 than the first end 23a (see Figure 2 Although not shown, the protrusion 23 may be configured in a manner opposite to this, such that the first end 23a is located closer to the impeller 10 rotation direction A side than the second end 23b in the circumferential direction of the inner surface 20a.

[0030] like Figure 2As shown, the tubular member 20 may include a tapered portion 24 whose inner diameter increases from the inlet end 21 toward the outlet end 22 between the inlet end 21 and the plurality of protrusions 23. In the structure in which the tubular member 20 includes the tapered portion 24, the protrusion 23 is preferably configured so that the surface 23c of the protrusion 23 is located at the same position as the inner surface 24c at the outlet 24b of the tapered portion 24 in the radial direction of the tubular member 20, or is located at a position further outward than the inner surface 24c at the outlet 24b of the tapered portion 24.

[0031] like Figure 5 As shown, in the structure where the cylindrical member 20 includes the tapered portion 24, at the hub side edge 12c where the impeller 12 is connected to the hub 11, if the distance from the leading edge 12a to the trailing edge 12b of the impeller 10 in the direction of the rotation axis RA of the impeller 10 is L 0 , the distance from the leading edge 12a to each of the inlet 24a and the outlet 24b of the tapered portion 24 in the direction of the rotation axis RA on the hub side edge 12c of each of the plurality of moving blades 12 is defined as L 1 and L 2 ,but

[0032] Preferred L 0 ≤L 1 ≤ 1.1 L 0 And 1.1L 1 ≤L 2 ≤1.5L 1 .

[0033] <Operation of Turbine According to One Embodiment of the Present Disclosure>

[0034] like Figure 1 As shown in FIG. 1 , if the exhaust gas discharged from the internal combustion engine 2 flows into the turbine 3, then Figure 2 As shown, the exhaust gas flow EG flows between adjacent blades 12 with increased velocity and flows into the diffuser 15. The velocity difference, i.e., static pressure difference, between the exhaust gas flow EG at the inlet and outlet of the blade 12 generates torque applied to the blade surface of the blade 12, and the impeller 10 rotates.

[0035] exist Figure 6 FIG. 2 shows the density of the flow velocity distribution of the exhaust gas in the diffuser 15' (without the protrusion 23) of the conventional structure (the greater the flow velocity, the darker the color) and the streamlines of the exhaust gas. However, in the diffuser 15' of the conventional structure, the flow EG of the exhaust gas passing through the moving blades 12 generally includes a swirling flow. Therefore, the flow EG of the exhaust gas approaches the shroud side, and a counter-flow vortex S is generated radially inward of the flow T of the exhaust gas near the shroud side. In the turbine 3, as shown in FIG. Figure 7As shown in FIG. 1 , a plurality of protrusions 23 are formed to protrude radially inwardly of the tubular member 20, thereby generating a flow separation P between adjacent protrusions 23. By this separation P, as shown in FIG. Figure 8 As shown (about the exhaust gas velocity distribution and streamlines, and Figure 6 The exhaust gas flow T near the shroud side is generally deviated radially inward. By being attracted by the exhaust gas flow in the diffuser 15, as shown in FIG. Fig. 9 As shown, the flow velocity of the flow F near the center of the span direction of the moving blade 12 in the flow of the exhaust gas between the adjacent moving blades 12 increases. As a result, the flow velocity difference of the fluid between the inlet and outlet of the moving blade 12 increases, that is, the static pressure difference between the inlet and outlet of the moving blade 12 increases, and the torque applied to the blade surface of the moving blade 12 increases, so that the performance of the turbine 3 can be improved.

[0036] The flow of exhaust gas at the outlet of the rotor blade 12 generally has a flow velocity distribution in which the flow velocity decreases from the shroud side toward the radial inner side. Such radial non-uniformity of the flow velocity becomes a loss, and the performance of the turbine 3 is reduced. Figure 2 In the turbine 3 shown, the exhaust gas flowing out of the moving blades 12 flows in the tapered portion 24, thereby suppressing the increase in the flow velocity of the exhaust gas on the shroud side at the outlet of the moving blades 12. Therefore, the radial unevenness of the flow velocity can be suppressed, and the reduction in the performance of the turbine 3 can be suppressed.

[0037] When the tubular member 20 includes the tapered portion 24, if the surface 23c of the protrusion 23 is located inwardly of the inner surface 24c at the outlet 24b of the tapered portion 24 in the radial direction of the tubular member 20, a part of the fluid flowing in the diffuser 15 is directed radially inward by the protrusion 23. Figure 8 The effect of increasing the flow velocity of the flow near the center of the span direction of the moving blade 12 is reduced by interfering with the flow T) of the moving blade 12. In contrast, in the turbine 3, the protrusion 23 is configured so that the surface 23c of the protrusion 23 is located at the same position as the inner surface 24c at the outlet 24b of the tapered portion 24 in the radial direction of the tubular member 20, or is located outside the inner surface 24c at the outlet 24b of the tapered portion 24, so that the reduction of the above-mentioned effect can be suppressed.

[0038] In addition, the turbine 3 has the above-mentioned structure (see Figure 5 ),Right now

[0039] L 0 ≤L 1 ≤ 1.1 L 0 And 1.1L 1 ≤L 2 ≤1.5L 1The structure can improve the above-mentioned effects.

[0040] like Figure 2 as well as Figure 3 As shown in FIG. 1 , when the protrusion 23 is configured so that the first end 23a and the second end 23b are located at the same position in the circumferential direction of the inner surface 20a, if the exhaust gas passing through the moving blade 12 does not include a swirling flow, the protrusion 23 is unlikely to become an obstacle to the flow of the exhaust gas flowing on the shroud side, and therefore, the exhaust gas passing through the moving blade 12 can flow smoothly in the diffuser 15. As a result, the performance of the turbine 3 can be improved.

[0041] However, the exhaust gas that has passed through the moving blades 12 generally includes a swirling flow. The exhaust gas that has passed through the moving blades 12 includes a swirling flow along the impeller 10 (see Figure 2 ) includes a swirling flow in the rotation direction A of the impeller 10, and a swirling flow in the direction opposite to the rotation direction A of the impeller 10 on the small flow side. Figure 4 As shown, if the protrusion 23 is configured so that the second end 23b is located closer to the rotation direction A side of the impeller 10 than the first end 23a in the circumferential direction of the inner surface 20a, the protrusion 23 is twistedly extended with respect to the rotation axis RA in a manner along the rotation direction A of the impeller 10, and thus, on the flow side, the swirling flow along the rotation direction A of the impeller 10 can flow between adjacent protrusions 23, so that the fluid passing through the moving blades 12 can flow smoothly in the diffuser 15. As a result, the performance of the turbine 3 on the large flow side can be improved.

[0042] On the other hand, if the protrusion 23 is configured so that the first end 23a is located closer to the rotation direction A side of the impeller 10 than the second end 23b in the circumferential direction of the inner surface 20a, the protrusion 23 is twistedly extended with respect to the rotation axis RA in a direction opposite to the rotation direction A of the impeller 10, and thus, on the small flow side, the swirling flow in the direction opposite to the rotation direction A of the impeller 10 can flow between adjacent protrusions 23, so that the fluid passing through the moving blades 12 can flow smoothly in the diffuser 15. As a result, the performance of the turbine 3 on the small flow side can be improved.

[0043] In the above embodiment, the turbine 3 of the turbocharger 1 is described, but the structure of the above embodiment can also be applied to turbines other than turbochargers. In this case, the fluid flowing into the turbine is not necessarily exhaust gas, but a fluid corresponding to the structure of the turbine.

[0044] The contents described in the above-mentioned embodiments can be understood, for example, as follows.

[0045] [1] A turbine according to one embodiment comprises:

[0046] An impeller (10) having a hub (11) provided with a plurality of moving blades (12) and capable of rotating; and

[0047] a tubular member (20) having a diffuser (15) formed therein and located on the downstream side of the impeller (10);

[0048] A plurality of protrusions (23) are formed on the inner surface (20a) of the tubular member (20) at positions closer to the inlet end (21) of the tubular member (20) than the outlet end (22) of the tubular member (20) so as to protrude radially inwardly of the tubular member (20).

[0049] The plurality of protrusions (23) are arranged along the circumferential direction of the inner surface (20a) with intervals between adjacent protrusions (23).

[0050] The fluid passing through the moving blades usually contains a swirling flow, so the flow of the fluid approaches the shroud side and generates a countercurrent vortex on its radial inner side. In contrast, according to the turbine disclosed in the present invention, a plurality of protrusions protruding radially inwardly of the tubular member are formed, and flow separation occurs between adjacent protrusions. Through this separation, the flow of the fluid close to the shroud side is shifted radially inward as a whole. By being attracted by the flow of the fluid in such a diffuser, the flow velocity of the flow between adjacent moving blades and near the center of the span direction of the moving blade increases. As a result, the flow velocity difference of the fluid between the inlet and outlet of the moving blade increases, that is, the static pressure difference between the inlet and outlet of the moving blade increases, and the torque applied to the blade surface of the moving blade increases, thereby improving the performance of the turbine.

[0051] [2] Another embodiment of the present invention relates to a turbine in the turbine of [1],

[0052] The tubular member (20) includes a tapered portion (24) between the inlet end (21) and the plurality of protrusions (23), the inner diameter of which increases from the inlet end (21) toward the outlet end (22).

[0053] The flow of the fluid at the outlet of the moving blade generally has a flow velocity distribution in which the flow velocity decreases from the shroud side toward the radial inner side. Such radial non-uniformity of the flow velocity becomes a loss, and the performance of the turbine is reduced. In contrast, according to the structure [2] above, the fluid flowing out of the moving blade flows in the conical portion, thereby suppressing the increase in the flow velocity of the fluid on the shroud side at the outlet of the moving blade, thereby suppressing the radial non-uniformity of the flow velocity and suppressing the reduction in the performance of the turbine.

[0054] [3] A turbine according to another embodiment is the turbine of [2],

[0055] The surfaces (23c) of the plurality of protrusions (23) are located at the same position as the inner surface (24c) at the outlet (24b) of the tapered portion (24) in the radial direction of the tubular member (20), or are located at a position outside the inner surface (24c) at the outlet (24b) of the tapered portion (24).

[0056] If the surfaces of the plurality of protrusions are located radially inward of the inner surface of the outlet of the tapered portion, a portion of the fluid flowing in the diffuser is directed radially inward by the protrusions. This interferes with the flow of the fluid that is deflected radially inward by the structure of [1], thereby reducing the effect obtained by the structure of [1]. In contrast, according to the structure of [3], the reduction in the effect obtained by the structure of [1] can be suppressed.

[0057] [4] A turbine according to another embodiment is the turbine of [2] or [3],

[0058] On the hub side edge (12c) where the plurality of moving blades (12) are respectively connected to the hub (11), if the distance from the leading edge (12a) to the trailing edge (12b) of each of the plurality of moving blades (12) in the direction of the rotation axis (RA) of the impeller 10 is set to L 0 ,

[0059] The distance in the direction of the rotation axis (RA) from the leading edge (12a) to each of the inlet (24a) and the outlet (24b) of the tapered portion (24) on the hub side edge (12c) of each of the plurality of moving blades (12) is defined as L. 1 and L 2 ,but

[0060] L 0 ≤L 1 ≤ 1.1 L 0 And 1.1L 1 ≤L 2 ≤1.5L 1 .

[0061] According to such a structure, the effect obtained from the structure of the above-mentioned [2] can be improved.

[0062] [5] A turbine according to another embodiment is the turbine according to any one of [1] to [4],

[0063] The plurality of protrusions (23) each have a shape including a first end (23a) on the inlet end (21) side and a second end (23b) on the outlet end (22) side and extending from the first end (23a) to the second end (23b),

[0064] In the circumferential direction of the inner surface (20a), the first end (23a) and the second end (23b) are located at the same position.

[0065] According to such a structure, when the fluid passing through the moving blades does not include swirling flow, the protrusions are unlikely to become obstacles to the flow of the fluid flowing on the shroud side, so the fluid passing through the moving blades can flow smoothly in the diffuser. As a result, the performance of the turbine can be improved.

[0066] [6] A turbine according to another embodiment is the turbine according to any one of [1] to [4],

[0067] The plurality of protrusions (23) each have a shape including a first end (23a) on the inlet end (21) side and a second end (23b) on the outlet end (22) side and extending from the first end (23a) to the second end (23b),

[0068] In the circumferential direction of the inner surface (20a), the second end (23b) is located closer to the rotation direction (A) of the impeller (10) than the first end (23a).

[0069] On the large flow side, the fluid passing through the moving blades includes a swirling flow along the rotation direction of the impeller. According to the structure of [6] above, the protrusions are twisted and extended relative to the rotation axis in a manner along the rotation direction of the impeller, thereby allowing the swirling flow along the rotation direction of the impeller to flow between adjacent protrusions, so that the fluid passing through the moving blades can flow smoothly in the diffuser. As a result, the performance of the turbine on the large flow side can be improved.

[0070] [7] A turbine according to another embodiment is the turbine according to any one of [1] to [4],

[0071] The plurality of protrusions (23) each have a shape including a first end (23a) on the inlet end (21) side and a second end (23b) on the outlet end (22) side and extending from the first end (23a) to the second end (23b),

[0072] In the circumferential direction of the inner surface (20a), the first end (23a) is located closer to the rotation direction (A) of the impeller (10) than the second end (23b).

[0073] On the small flow side, the fluid passing through the moving blades includes a swirling flow in the direction opposite to the rotation direction of the impeller. According to the structure of [7] above, the protrusions are twisted and extended relative to the rotation axis in the direction opposite to the rotation direction of the impeller, thereby allowing the swirling flow in the direction opposite to the rotation direction of the impeller to flow between adjacent protrusions, so that the fluid passing through the moving blades can flow smoothly in the diffuser. As a result, the performance of the turbine on the small flow side can be improved.

[0074] [8] A turbocharger according to one embodiment includes the turbine (3) according to any one of [1] to [7].

[0075] According to the turbocharger of the present disclosure, since the turbine having improved performance is provided, the performance of the turbocharger can be improved.

[0076] Description of Reference Numerals

[0077] 1 Turbocharger

[0078] 3 Turbine

[0079] 10 Impeller

[0080] 11 Wheels

[0081] 12 moving blades

[0082] 12a Leading edge (of moving blade)

[0083] 12b trailing edge (of moving blade)

[0084] 12c (rotor blade) hub side edge

[0085] 15 Diffuser

[0086] 20 cylindrical parts

[0087] 20a Inner surface (of the cylindrical member)

[0088] 21 Entrance

[0089] 22Export port

[0090] 23 Protrusion

[0091] 23a First end (of the protrusion)

[0092] 23b Second end (of the protrusion)

[0093] 23c Surface (of the protrusion)

[0094] 24 cone

[0095] 24a (conical part) entrance

[0096] 24b (conical part) outlet

[0097] A (impeller) rotation direction

[0098] RA (impeller) rotation axis

Claims

1. A turbine, wherein: The turbine has: an impeller having a hub provided with a plurality of moving blades and being rotatable; and a tubular member having a diffuser formed on the downstream side of the impeller, A plurality of protrusions are formed on the inner surface of the tubular member at positions closer to the inlet end of the tubular member than to the outlet end of the tubular member, and protrude toward the radial inner side of the tubular member. The plurality of protrusions are arranged along the circumferential direction of the inner surface with intervals between adjacent protrusions. The cylindrical member includes a tapered portion between the inlet end and the plurality of protrusions, the inner diameter of which increases from the inlet end toward the outlet end.

2. The turbine according to claim 1, wherein: The surfaces of the plurality of protrusions are located at the same position as the inner surface of the outlet of the tapered portion or at a position outside the inner surface of the outlet of the tapered portion in the radial direction of the tubular member.

3. A turbine according to claim 1 or 2, wherein: On the hub side edge where the plurality of moving blades are connected to the hub, if the distance from the leading edge to the trailing edge of each of the plurality of moving blades in the direction of the rotation axis of the impeller is defined as L0, Assuming that the distances from the leading edge on the hub side edge of each of the plurality of rotor blades to the inlet and the outlet of the tapered portion in the direction of the rotation axis are L1 and L2, L0≤L1≤1.1L0 and 1.1L1≤L2≤1.5L1.

4. The turbine according to claim 1, wherein: The plurality of protrusions each have a shape including a first end on the inlet end side and a second end on the outlet end side and extending from the first end to the second end. The first end and the second end are located at the same position in the circumferential direction of the inner surface.

5. The turbine according to claim 1, wherein: The plurality of protrusions each have a shape including a first end on the inlet end side and a second end on the outlet end side and extending from the first end to the second end. In the circumferential direction of the inner surface, the second end is located closer to the rotation direction of the impeller than the first end.

6. The turbine of claim 1, wherein: The plurality of protrusions each have a shape including a first end on the inlet end side and a second end on the outlet end side and extending from the first end to the second end. In the circumferential direction of the inner surface, the first end is located closer to the rotation direction side of the impeller than the second end.

7. A turbocharger, wherein: A turbine according to any one of claims 1 to 6 is provided.

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