turbocharger

Abstract

The turbocharger includes: an impeller having a hub rotatably arranged about a central axis, and a plurality of moving blades arranged radially outward of the hub at intervals in a circumferential direction about the central axis; a turbine housing arranged radially outward of the impeller and forming a vortex flow path for swirling exhaust gas in a circumferential direction and guiding the exhaust gas toward the impeller radially inward, wherein at least one of a plurality of inter-blade flow path portions formed between the plurality of moving blades has a circumferential flow path width different from the flow path widths of the other inter-blade flow path portions.

Description

Technical Field

[0001] The present disclosure relates to turbochargers. Background Art

[0002] In rotating machines such as turbochargers (superchargers), various improvements are constantly being made to improve efficiency, suppress vibration, reduce noise, and the like.

[0003] For example, Patent Document 1 discloses a structure in which the throat width of a portion of the circumferential direction of a stationary blade is made different from the standard throat width of the rest of the circumferential direction, thereby avoiding resonance with a moving blade.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 3181200 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, turbochargers include a scroll portion that swirls exhaust gas from the engine in a circumferential direction radially outside the impeller and guides it toward the impeller's moving blades radially inside. To improve turbocharger efficiency, it is desirable to minimize the gap between the tongue portion of the scroll portion, located radially outside the impeller, and the impeller's moving blades. However, reducing the gap between the tongue portion and the moving blades can cause noise in the low-velocity exhaust gas flow area downstream of the tongue portion due to pressure fluctuations as the moving blades pass through it.

[0009] The present disclosure is proposed to solve the above-mentioned problem and provides a turbocharger capable of suppressing noise.

[0010] Technical solutions to solve problems

[0011] In order to solve the above-mentioned problems, the present disclosure provides a turbocharger comprising: an impeller having a hub rotatably arranged around a central axis, and a plurality of moving blades arranged at intervals in a circumferential direction around the central axis on a radially outer side of the hub; a turbine housing arranged radially outer side of the impeller and forming a vortex flow path for causing exhaust gas to swirl in a circumferential direction and guide the exhaust gas toward the impeller on a radially inner side, wherein at least one of a plurality of inter-blade flow path portions formed between the plurality of moving blades has a flow path width in the circumferential direction that is different from the flow path widths of the other inter-blade flow path portions.

[0012] Effects of the Invention

[0013] According to the turbocharger of the present disclosure, noise can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a diagram showing a schematic configuration of a turbocharger according to an embodiment of the present disclosure.

[0015] Figure 2 This is a diagram of the turbine of the turbocharger according to the first embodiment of the present disclosure as viewed from the center axis direction.

[0016] Figure 3 This is a diagram of an impeller constituting the turbine according to the first embodiment of the present disclosure, as viewed from the center axis direction.

[0017] Figure 4 It is a diagram showing simulation results of load fluctuations of the impeller according to the first embodiment of the present disclosure.

[0018] Figure 5 Is based on Figure 4 A plot of the frequency distribution of noise from the simulation results.

[0019] Figure 6 It is a diagram showing simulation results of load fluctuations on an impeller according to a modification of the first embodiment of the present disclosure.

[0020] Figure 7 Is based on Figure 6 A plot of the frequency distribution of noise from the simulation results.

[0021] Figure 8 This is a diagram of an impeller constituting a turbine according to a second embodiment of the present disclosure, as viewed from the center axis direction.

[0022] Figure 9 It is a diagram showing simulation results of load fluctuations of the impeller according to the second embodiment of the present disclosure.

[0023] Figure 10 Is based on Figure 9 A plot of the frequency distribution of noise from the simulation results.

[0024] Figure 11 This is a diagram of an impeller constituting a turbine according to a third embodiment of the present disclosure, as viewed from the center axis direction.

[0025] Figure 12 This is a diagram of an impeller constituting a turbine according to a fourth embodiment of the present disclosure, as viewed from the center axis direction. DETAILED DESCRIPTION

[0026] <First embodiment>

[0027] Hereinafter, the turbocharger of the present disclosure will be described with reference to the accompanying drawings.

[0028] (Structure of a turbocharger)

[0029] like Figure 1As shown, the turbocharger 10 includes a turbocharger body 11, a compressor 20, and a turbine 30. The turbocharger 10 is mounted on an automobile or the like as an auxiliary machine of an engine, for example.

[0030] The turbocharger body 11 includes a bearing housing 12 and a rotating shaft 13 .

[0031] The bearing housing 12 is supported by a vehicle body, etc., via a bracket (not shown), the compressor 20, the turbine 30, etc. The rotating shaft 13 is housed within the bearing housing 12. The rotating shaft 13 is rotatably supported within the bearing housing 12 about the central axis C via bearings 14A and 14B. Both ends of the rotating shaft 13 in the direction of the central axis C protrude from the bearing housing 12.

[0032] The compressor 20 is arranged on one end side in the direction of the central axis C of the bearing housing 12. The compressor 20 includes a compressor wheel 21 and a compressor housing 22. The compressor wheel 21 is connected to the end of the rotating shaft 13 outside the bearing housing 12. The compressor wheel 21 rotates integrally with the rotating shaft 13 around the central axis C. The compressor housing 22 is connected to one end side in the direction of the central axis C of the bearing housing 12. The compressor housing 22 accommodates the compressor wheel 21 inside. A flow path 22r for air introduced from the outside is formed in the compressor housing 22. The flow path 22r guides the air introduced from the outside to the compressor wheel 21, and sends the air that has passed through the compressor wheel 21 into the engine (not shown).

[0033] (Turbine Structure)

[0034] The turbine 30 is arranged on the other end side of the bearing housing 12. The turbine 30 includes a turbine housing 40 and an impeller 31A.

[0035] The turbine housing 40 is connected to the other end side of the bearing housing 12. The turbine housing 40 is arranged outside the impeller 31A in the radial direction Dr centered on the central axis C. The turbine housing 40 accommodates the impeller 31A therein.

[0036] like Figure 2 As shown, the turbine housing 40 includes a gas inlet (not shown) and swirl channels 43 and 44. The gas inlet (not shown) opens to the outside and introduces exhaust gas discharged from an engine (not shown) into the turbine housing 40.

[0037] The swirl flow paths 43 and 44 are formed in the turbine housing 40. The swirl flow paths 43 and 44 swirl the exhaust gas that rotates the impeller 31A in the circumferential direction Dc and guide the exhaust gas gradually toward the inside in the radial direction Dr.

[0038] The turbine housing 40 has a cylindrical peripheral wall 41 and an intermediate wall 42 formed within the peripheral wall 41. The peripheral wall 41 is generally spirally shaped, extending continuously from a gas inlet (not shown) in the circumferential direction Dc and gradually extending inward in the radial direction Dr. The intermediate wall 42 divides the interior of the cylindrical peripheral wall 41 into an outer side in the radial direction Dr and an inner side in the radial direction Dr, centered on the central axis C. This creates a vortex flow path 43, located radially outward of the intermediate wall 42, and a vortex flow path 44, located radially inward of the intermediate wall 42, within the peripheral wall 41 of the turbine housing 40.

[0039] The peripheral wall 41 and the intermediate wall 42 have tongue portions 41s and 42s at positions proximate to the outer side of the impeller 31A in the radial direction Dr. The tongue portion 41s of the peripheral wall 41 and the tongue portion 42s of the intermediate wall 42 are positioned approximately 180° apart in the circumferential direction Dc, with the impeller 31A sandwiched between them. The vortex flow path 43 and the vortex flow path 44 have nozzle portions 43n and 44n, respectively, that open toward the impeller 31A inward in the radial direction Dr. The nozzle portions 43n and 44n face each other in the radial direction Dr, with the impeller 31A sandwiched between them. The nozzle portion 43n of the vortex flow path 43 opens across approximately 180° in the circumferential direction Dc, between the tongue portion 41s of the peripheral wall 41 and the tongue portion 42s of the intermediate wall 42. The nozzle portion 44 n of the swirl flow path 44 is open over approximately 180° in the circumferential direction Dc between the tongue portion 42 s of the intermediate wall 42 and the tongue portion 41 s of the peripheral wall 41 .

[0040] In addition, if Figure 1 As shown, an exhaust portion 45 for discharging exhaust gas discharged from the impeller 31A toward the central axis C is formed on the inner side of the peripheral wall 41 in the radial direction Dr of the turbine housing 40 .

[0041] Exhaust gas is supplied from the engine (not shown) to the gas inlet (not shown) of the turbine housing 40. Exhaust gas flowing from the gas inlet (not shown) swirls along the vortex flow paths 43 and 44, swirling in the circumferential direction Dc outside the impeller 31A in the radial direction Dr, gradually flowing inward in the radial direction Dr. Exhaust gas is supplied from nozzles 43n and 44n to the impeller 31A inward in the radial direction Dr. The collision of the exhaust gas causes the impeller 31A to rotate about the central axis C. Exhaust gas passing through the impeller 31A is discharged from the inside of the impeller 31A in the radial direction Dr through the exhaust port 45.

[0042] By rotating the impeller 31A, the rotating shaft 13 and the compressor wheel 21 rotate integrally with the impeller 31A about the central axis C. The compressor wheel 21 compresses air introduced from the outside into the compressor housing 22 by rotating about the central axis C. The air compressed by the compressor 20 is supplied from the compressor housing 22 to the engine (not shown).

[0043] (Impeller structure)

[0044] The impeller 31A is arranged outside the bearing housing 12 at the other end side of the central axis C direction of the rotating shaft 13. The impeller 31A rotates integrally with the rotating shaft 13 around the central axis C. Figures 1 to 3 As shown, the impeller 31A integrally includes a hub 32 and rotor blades 33 .

[0045] The hub 32 is fixed to the other end of the rotating shaft 13 in the direction of the central axis C. The hub 32 is rotatable integrally with the rotating shaft 13 about the central axis C. The hub 32 is disc-shaped when viewed from the direction of the central axis C. The hub 32 has a center portion 32a on the inner side in the radial direction Dr, which has a constant thickness along the direction of the central axis C. The thickness of the hub 32 in the direction of the central axis C gradually decreases from the center portion 32a toward the outer side in the radial direction Dr. The hub 32 has a disc surface 32f on the side facing the exhaust portion 45 in the direction of the central axis C. The disc surface 32f is formed by a concave curved surface that gradually extends from the side closest to the exhaust portion 45 in the direction of the central axis C toward the bearing housing 12 side opposite the exhaust portion 45 in the direction of the central axis C as it moves toward the outer side in the radial direction Dr.

[0046] A plurality of rotor blades 33 are arranged on the disk surface 32f at intervals along the circumferential direction Dc around the central axis C. In the embodiment of the present disclosure, the impeller 31A includes, for example, ten rotor blades 33 .

[0047] Each rotor blade 33 has a leading edge 33f and a trailing edge 33r. The leading edge 33f faces outward in the radial direction Dr, facing the nozzle portions 43n and 44n of the swirl flow paths 43 and 44. The leading edge 33f is disposed with a gap defined in the radial direction Dr between the tongue portion 41s of the peripheral wall 41 and the tongue portion 42s of the intermediate wall 42, which are located outward in the radial direction Dr. The trailing edge 33r faces the other side in the direction of the central axis C, facing the exhaust portion 45.

[0048] like Figure 3 As shown, in such an impeller 31A, inter-blade flow paths R are formed between adjacent blades 33 in the circumferential direction Dc. Exhaust gas flowing from the vortex flow paths 43 and 44 on the outside of the impeller 31A in the radial direction Dr toward the inside of the radial direction Dr passes through the inter-blade flow paths R between the adjacent blades 33 in the circumferential direction Dc. Exhaust gas flowing from the leading edge 33f of the blade 33 toward the inside of the radial direction Dr is redirected by the curvature of the disk surface 32f and is discharged from the trailing edge 33r of the blade 33 along the central axis C. The impeller 31A has a plurality of such inter-blade flow paths R in the circumferential direction Dc.

[0049] In the impeller 31A, the flow path width in the circumferential direction Dc of at least one inter-blade flow path portion R1 among the plurality of inter-blade flow paths R formed between the plurality of moving blades 33 is different from the flow path widths of the other inter-blade flow paths R2. In the embodiment of the present invention, the impeller 31A includes the inter-blade flow paths R1 and the inter-blade flow paths R2, each having a different flow path width in the circumferential direction Dc.

[0050] For example, the flow path width may be an angle formed between adjacent moving blades 33 on the leading edge 33 f side of the moving blade 33 .

[0051] For example, the inter-blade flow path portion R1 may be formed between adjacent rotor blades 33 at an angle θ1.

[0052] For example, the inter-blade flow path portion R2 may be formed between adjacent moving blades 33 at an angle θ2.

[0053] For example, in the embodiment of the present disclosure, the angle θ1 may also be smaller than the angle θ2.

[0054] For example, the angle θ1 may be set to 31°.

[0055] For example, the angle θ2 may be set to 41°.

[0056] For example, the inter-blade flow path portions R1 and the inter-blade flow path portions R2 having flow path widths different from each other in the circumferential direction Dc may be alternately arranged in the circumferential direction Dc.

[0057] If the thickness of the rotor blades 33 in the circumferential direction Dc is not negligible relative to the included angle, the included angle may be the angle formed by the opposing surfaces of adjacent rotor blades 33. In this case, for example, the included angle θ1 may be set to an angle obtained by subtracting an angle corresponding to the thickness of the rotor blades 33 in the circumferential direction Dc from 31°, and the included angle θ2 may be set to an angle obtained by subtracting an angle corresponding to the thickness of the rotor blades 33 in the circumferential direction Dc from 41°.

[0058] However, including Figure 3 Including the case of , the following description will focus on the case where the thickness of the rotor blade 33 in the circumferential direction Dc is a thickness that is negligible with respect to the included angle.

[0059] Thus, the impeller 31A has a plurality of moving blades 33 arranged at unequal intervals in the circumferential direction Dc. The impeller 31A has a total of five sets of two types of inter-blade flow paths R1 and R2 having different flow path widths (angles) in the circumferential direction Dc.

[0060] Here, the two inter-blade flow passage sections R1 and R2, each with different flow passage widths (included angles) in the circumferential direction Dc, include a moving blade group G1 (first moving blade group) and a moving blade group G2 (second moving blade group), each consisting of five moving blades 33. Each moving blade group G1 and G2 consists of five moving blades 33 arranged at equal intervals of 72° in the circumferential direction Dc. The moving blades 33 of the moving blade group G2 are arranged with their phases shifted clockwise in the circumferential direction Dc relative to the moving blades 33 of the moving blade group G1.

[0061] Therefore, by unitizing the five moving blade groups G1 and G2 and forming them with their phases shifted, it is possible to easily configure a plurality of moving blades 33 arranged at unequal intervals in the circumferential direction Dc as a whole.

[0062] Therefore, the turbocharger 10 can be easily manufactured.

[0063] When the load (pressure) variation acting on the tongues 41s and 42s is simulated using such an impeller 31A, as shown in FIG. Figure 4 In the pressure fluctuation waveform W1 shown, the impeller 31A rotates about the central axis C, and the tongue portions 41s and 42s approach the multiple rotor blades 33, resulting in load fluctuations with unequal pitches. In contrast, for comparison, the same simulation was performed for a case where multiple rotor blades are arranged at equal intervals in the circumferential direction Dc. The results show that the pressure fluctuation waveform W2 produces load fluctuations with equal pitches.

[0064] Furthermore, when the frequency analysis of the pressure variation waveforms W1 and W2 is performed, Figure 5 As shown, when the plurality of moving blades are arranged at equal intervals along the circumferential direction Dc, the load fluctuation is concentrated in a specific frequency region f. In contrast, when the plurality of moving blades 33 are arranged at unequal intervals so that the flow path width in the circumferential direction Dc of the inter-blade flow path portion R1 is different from the flow path width of the inter-blade flow path portion R2, the load fluctuation is dispersed in multiple frequency regions.

[0065] According to the turbocharger 10 of the embodiment described above, the flow path width in the circumferential direction Dc of some inter-blade flow paths R1 among the plurality of inter-blade flow paths R differs from the flow path width of other inter-blade flow paths R2. As a result, the pressure fluctuations generated in the gaps between the plurality of moving blades 33 and the tongue portions 41s and 42s are of unequal pitch. Consequently, the frequency of noise generated in the gaps can be dispersed without widening the gaps between the plurality of moving blades 33 and the tongue portions 41s and 42s. This reduces noise at specific frequencies, thus suppressing noise.

[0066] Furthermore, in the turbocharger 10 described above, the respective moving blades 33 of the second moving blade group G2 are arranged in a phase shifted in the circumferential direction Dc with respect to the respective moving blades 33 of the first moving blade group G1 .

[0067] Thus, by unitizing the first and second moving blade groups G1 and G2 and arranging them with their phases shifted, it is possible to easily configure a plurality of moving blades 33 arranged at unequal intervals in the circumferential direction Dc as a whole.

[0068] Therefore, the turbocharger 10 can be easily manufactured.

[0069] In particular, as in the turbocharger 10 described above, if the number of blades 33 in the impeller 31A is an even number, the impeller 31A can be configured so that the number of blades 33 in the first blade group G1 and the number of blades 33 in the second blade group G2 are the same.

[0070] Therefore, when the first moving blade group G1 and the second moving blade group G2 are combined, it is easy to achieve balance at the center of the impeller 31A.

[0071] (Modification of the first embodiment)

[0072] In the above embodiment, the angle θ1 of the inter-blade flow path portion R1 is set to 31°, and the angle θ2 of the inter-blade flow path portion R2 is set to 41°. However, the present invention is not limited thereto. The angle θ1 of the inter-blade flow path portion R1 and the angle θ2 of the inter-blade flow path portion R2 can be appropriately changed.

[0073] For example, the angle θ1 of the inter-blade flow path portion R1 may be set to 26°, and the angle θ2 of the inter-blade flow path portion R2 may be set to 46°. Figure 6 As shown in FIG, in the impeller 31A where the angles θ1 and θ2 are different, load fluctuations with unequal intervals are also generated as shown in the pressure fluctuation waveform W1'. The pressure fluctuation waveform W1' has a larger deviation than the pressure fluctuation waveform W2 when the moving blades 33 are arranged at equal intervals. Figure 7 As shown, when Figure 6 When performing frequency analysis on the pressure variation waveform W1', the plurality of moving blades 33 are arranged at unequal intervals so that the flow path width in the circumferential direction Dc of the inter-blade flow path portion R1 is different from the flow path width of the inter-blade flow path portion R2. As a result, the load variation is further dispersed in other frequency regions, and the peak value of the load (noise) in the specific frequency range f is greatly reduced.

[0074] <Second embodiment>

[0075] Next, a turbocharger according to a second embodiment of the present disclosure will be described.

[0076] In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The arrangement of the plurality of rotor blades 33 of the turbocharger of the second embodiment is different from that of the first embodiment.

[0077] like Figure 8 As shown, the impeller 31B constituting the turbine 30 of the turbocharger 10 of the second embodiment is provided with, for example, ten rotor blades 33 spaced apart in the circumferential direction Dc, similar to the first embodiment.

[0078] In the impeller 31B of the embodiment of the present invention, the multiple inter-blade flow paths R formed between the plurality of moving blades 33 include five types of inter-blade flow paths R11 to R15, each having a different flow path width in the circumferential direction Dc. The five types of inter-blade flow paths R11 to R15 have different angles θ11 to θ15 between adjacent moving blades 33. The inter-blade flow path R11 is formed at an angle θ11 between adjacent moving blades 33. In the disclosed embodiment, the angle θ11 is set to, for example, 42°. The inter-blade flow path R12 is formed at an angle θ12 between adjacent moving blades 33. The angle θ12 is set to, for example, 39°. The inter-blade flow path R13 is formed at an angle θ13 between adjacent moving blades 33. The angle θ13 is set to, for example, 33°. The inter-blade flow path R14 is formed at an angle θ14 between adjacent moving blades 33. The angle θ14 is set to, for example, 30°. The inter-blade flow path portion R15 is formed at the angle θ15 between the adjacent moving blades 33. The angle θ15 is set to, for example, 36°.

[0079] Thus, the impeller 31B has a plurality of moving blades 33 arranged at equal intervals in the circumferential direction Dc. The impeller 31B has two sets of five inter-blade flow path portions R11 to R15 with angles θ11 to θ15 arranged in the circumferential direction Dc.

[0080] Here, the five inter-blade flow path sections R11 to R15, each with different flow path widths (angles) in the circumferential direction Dc, include blade groups G1 to G5 (first to fifth blade groups), each consisting of two blades 33. Each blade group G1 to G5 is composed of two blades 33 arranged at equal intervals of 180° in the circumferential direction Dc. The blades 33 in the blade groups G1 to G5 are arranged with their phases shifted relative to each other in the circumferential direction Dc.

[0081] Therefore, by unitizing the two blade groups G1 to G5 and arranging them with their phases shifted, it is possible to easily configure a plurality of blades 33 arranged at unequal intervals in the circumferential direction Dc as a whole.

[0082] Therefore, the turbocharger 10 can be easily manufactured.

[0083] When the load (pressure) variation acting on the tongues 41s and 42s is simulated using the impeller 31B, as shown in FIG. Figure 9As shown in the pressure variation waveform W11, the impeller 31B rotates around the central axis C, and the plurality of moving blades 33 approach the tongue portions 41s and 42s, thereby generating load variations with unequal intervals. Furthermore, when the pressure variation waveform W11 is subjected to frequency analysis, as shown in FIG. Figure 10 As shown, when the plurality of moving blades 33 are arranged at unequal intervals so that the flow path widths in the circumferential direction Dc of the inter-blade flow path portions R11 to R15 are different from each other, Figure 5 、 Figure 7 Compared with the pressure fluctuation waveform W1 in the first embodiment shown, the load fluctuation is more dispersed in other frequency regions.

[0084] In the turbocharger 10 of the embodiment described above, the flow path widths of the plurality of inter-blade flow paths R11 to R15 differ from one another. This allows the frequency of noise generated in the gaps between the plurality of rotor blades 33 and the tongue portions 41s and 42s to be dispersed without widening the gaps. This reduces noise in the specific frequency region f, thus suppressing noise.

[0085] <Third embodiment>

[0086] Next, a turbocharger according to a third embodiment of the present disclosure will be described.

[0087] In the third embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. The structure of the hub 32 of the turbocharger of the third embodiment is different from that of the first embodiment.

[0088] like Figure 11 As shown, the impeller 31C of the turbine 30 constituting the turbocharger 10 of the third embodiment is similar to the first embodiment and includes, for example, ten rotor blades 33 spaced apart in the circumferential direction Dc.

[0089] The impeller 31C of the present embodiment, similar to the first embodiment, includes first and second inter-blade flow paths R21, R22, each having different flow path widths in the circumferential direction Dc. The first inter-blade flow paths R21 are formed at an angle θ21 (e.g., 31°) between adjacent blades 33. The second inter-blade flow paths R22 are formed at an angle θ22 (e.g., 41°) between adjacent blades 33. The impeller 31C includes a total of five sets of two types of first and second inter-blade flow paths R21, R22, each having different flow path widths (angles) in the circumferential direction Dc.

[0090] In this impeller 31C, the hub 32 has different diameters in the first inter-blade flow path section R21 and the second inter-blade flow path section R22, which have different flow path widths (angles) in the circumferential direction Dc. The diameter ra of the hub 32 in the first inter-blade flow path section R21 is larger than the diameter rb of the hub 32 in the second inter-blade flow path section R22, which has a larger flow path width than the first inter-blade flow path section R21. Consequently, in the narrower first inter-blade flow path section R21, the larger diameter ra of the hub 32 causes the disk surface 32fa of the hub 32 to be positioned further outward in the radial direction Dr than the disk surface 32fb of the hub 32 in the second inter-blade flow path section R22. Consequently, in the first inter-blade flow path section R21, the distance between the roots 33k of adjacent blades 33 in the circumferential direction Dc is substantially widened.

[0091] According to the turbocharger 10 of the embodiment described above, the hub 32 has a larger diameter ra in the first inter-blade flow path section R21, where the flow path width is narrow, and a smaller diameter rb in the second inter-blade flow path section R22, where the flow path width is wide. This facilitates curved surface processing, etc., of the portion 33j connecting the root 33k of the rotor blade 33 to the disk surface 32fa of the hub 32, even in the first inter-blade flow path section R21, where the flow path width is narrow. Furthermore, the radius of curvature of the portion 33j connecting the root 33k of the rotor blade 33 to the disk surface 32fa of the hub 32 can be increased, thereby suppressing stress concentration on the root 33k of the rotor blade 33.

[0092] In addition, similar to the above embodiment, the flow path widths of the first inter-blade flow path portion R21 and the second inter-blade flow path portion R22 are different from each other. This can reduce noise at a specific frequency, thereby suppressing noise.

[0093] <Fourth embodiment>

[0094] Next, a turbocharger according to a fourth embodiment of the present disclosure will be described.

[0095] In the fourth embodiment, the same components as those in the first to third embodiments are denoted by the same reference numerals, and detailed descriptions thereof are omitted. The turbocharger of the fourth embodiment differs from the first to third embodiments in the arrangement of the plurality of rotor blades 33G on the trailing edge 33r side downstream in the exhaust gas flow direction.

[0096] like Figure 12 As shown, the impeller 31D constituting the turbine 30 of the turbocharger 10 of the fourth embodiment is similar to the first embodiment and includes, for example, ten rotor blades 33G spaced apart in the circumferential direction Dc.

[0097] In the embodiment of the present disclosure, the plurality of moving blades 33G are arranged so that the minimum flow path areas between adjacent blades in the circumferential direction Dc are equal on the trailing edge 33r side on the downstream side in the flow direction of the exhaust gas.

[0098] On the other hand, the plurality of moving blades 33G are arranged at unequal intervals in the circumferential direction Dc on the leading edge 33f side on the upstream side in the flow direction of the exhaust gas.

[0099] The impeller 31D of this embodiment of the present invention, similar to the first embodiment, includes a first inter-blade flow path portion R31 and a second inter-blade flow path portion R32 having different flow path widths in the circumferential direction Dc. The first inter-blade flow path portion R31 is formed between adjacent blades 33G at an angle θ31 (e.g., 31°) toward the leading edge 33f. The second inter-blade flow path portion R32 is formed between adjacent blades 33G at an angle θ32 (e.g., 41°) toward the leading edge 33f.

[0100] On the other hand, the first inter-blade flow path portion R31 and the second inter-blade flow path portion R32 have the same angle θ41 on the trailing edge 33r side, and are therefore arranged so that the minimum flow path areas between adjacent blades are equal.

[0101] In the turbocharger 10 of the embodiment described above, the flow path widths of the first inter-blade flow path portion R31 and the second inter-blade flow path portion R32 are different on the leading edge 33f side upstream in the exhaust gas flow direction. This can suppress noise.

[0102] On the other hand, downstream in the exhaust gas flow direction, the plurality of moving blades 33G are arranged so that the minimum flow path areas between adjacent blades in the circumferential direction Dc are equal. Therefore, the load acting on the plurality of moving blades 33G can be made uniform downstream in the exhaust gas flow direction.

[0103] In addition, in the present embodiment, downstream in the flow direction of the exhaust gas, a plurality of moving blades 33G having equal thickness in the circumferential direction Dc of each moving blade 33 are arranged at equal intervals in the circumferential direction Dc, and the minimum flow path areas between adjacent blades in the circumferential direction Dc are arranged to be equal, but any configuration is also possible as long as the minimum flow path areas are arranged to be equal.

[0104] As a modified example, downstream in the flow direction of the exhaust gas, even if the plurality of moving blades 33G are unequally spaced in the circumferential direction Dc downstream in the flow direction of the exhaust gas, by making the thickness of each moving blade 33 in the circumferential direction Dc different, the plurality of moving blades 33G can be arranged so that the minimum flow path area between adjacent blades in the circumferential direction Dc is equal.

[0105] (Other embodiments)

[0106] While the embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the various structures and combinations thereof in the various embodiments are merely examples, and additions, omissions, substitutions, and other modifications may be made to the structures without departing from the spirit of the present disclosure. Furthermore, the present disclosure is not limited to the embodiments but only to the scope of the claims.

[0107] For example, in the above-mentioned embodiment, the flow path widths of the inter-blade flow path portion R are made different by making the angles between adjacent moving blades 33 in the circumferential direction Dc different, but as a modification, the flow path widths of the inter-blade flow path portion R can also be made different by making the thicknesses of each moving blade 33 in the circumferential direction Dc different.

[0108] In the above embodiment, ten rotor blades 33 are provided, but the number of rotor blades 33 is not limited at all and may be set to another number as appropriate. As a modified example, the number of rotor blades 33 may be an odd number.

[0109] Furthermore, in the above embodiment, the turbine housing 40 includes the two scroll flow paths 43 and 44 , but the present invention is not limited thereto.

[0110] As a modified example, the turbine housing 40 may be configured to include only one scroll flow path.

[0111] As another modified example, the turbine housing 40 may be configured to include two scroll flow paths arranged in the direction of the central axis C.

[0112] <Note>

[0113] The turbocharger 10 described in each embodiment can be understood, for example, as follows.

[0114] (1) A first aspect provides a turbocharger 10 comprising: impellers 31A to 31D having a hub 32 rotatably arranged about a central axis C, and a plurality of moving blades 33, 33G arranged at intervals along a circumferential direction Dc about the central axis C on the radially outer side Dr of the hub 32; a turbine housing 40 arranged on the radially outer side Dr of the impellers 31A to 31D and forming vortex flow paths 43, 44 for swirling exhaust gas along the circumferential direction Dc and guiding it toward the impellers 31A to 31D on the radially inner side Dr; and a plurality of inter-blade flow paths R formed between the plurality of moving blades 33, 33G, wherein the flow path width in the circumferential direction Dc of at least one of the inter-blade flow paths R1, R11, R21, R31 is different from the flow path widths of the other inter-blade flow paths R2, R12, R22, R32.

[0115] In this turbocharger 10, the plurality of rotor blades 33, 33G are arranged at unequal intervals. This allows the frequency of noise generated in the gaps to be dispersed without widening the gaps between the plurality of rotor blades 33, 33G and the tongue portions 41s, 42s arranged radially outward of the rotor blades 33, 33G in the turbine housing 40. This reduces noise at specific frequencies, thus suppressing noise.

[0116] (2) The turbocharger 10 of the second aspect is based on the turbocharger 10 of (1), and the plurality of moving blades 33, 33G include a first moving blade group G1 arranged at equal intervals in the above-mentioned circumferential direction Dc and a second moving blade group G2 arranged at equal intervals in the above-mentioned circumferential direction, and the above-mentioned each moving blade 33, 33G of the above-mentioned second moving blade group G2 is arranged in a phase-shifted manner in the above-mentioned circumferential direction Dc relative to the above-mentioned each moving blade 33, 33G of the above-mentioned first moving blade group G1.

[0117] Thus, by unitizing the first and second blade groups G1 and G2 and arranging them with their phases shifted, it is possible to easily configure the plurality of blades 33 and 33G arranged at unequal intervals in the circumferential direction Dc as a whole.

[0118] Therefore, the turbocharger 10 can be easily manufactured.

[0119] (3) The turbocharger 10 of the third aspect is based on the turbocharger 10 of (1) or (2), wherein the diameter dimension ra of the above-mentioned hub 32 in the first above-mentioned inter-blade flow path portion R21 is larger than the diameter dimension rb of the above-mentioned hub 32 in the second above-mentioned inter-blade flow path portion R22, and the second above-mentioned inter-blade flow path portion R22 has a flow path width larger than the above-mentioned first inter-blade flow path portion R21.

[0120] As a result, the hub 32 has a larger diameter ra in the narrow first inter-blade flow path section R21, while the hub 32 has a smaller diameter rb in the wide second inter-blade flow path section R22. In the narrow first inter-blade flow path section R21, the curved surface of the portion 33j connecting the root 33k of the rotor blade 33 and the disk surface 32f of the hub 32 can be easily machined. Furthermore, the radius of curvature of the portion 33j connecting the root 33k of the rotor blade 33 and the disk surface 32f of the hub 32 can be increased, thereby suppressing stress concentration on the root 33k of the rotor blade 33.

[0121] (4) The turbocharger 10 of the fourth aspect is based on the turbocharger 10 of any one of aspects (1) to (3), and the plurality of the above-mentioned moving blades 33G are arranged so that: on the downstream side of the flow direction of the above-mentioned exhaust gas, the minimum flow path areas between adjacent blades in the above-mentioned circumferential direction Dc are equal, and on the upstream side of the flow direction of the above-mentioned exhaust gas, the minimum flow path areas between adjacent blades in the above-mentioned circumferential direction Dc are unequal.

[0122] As a result, multiple blades 33 are arranged at equal intervals in the circumferential direction Dc on the upstream side of the exhaust gas flow direction. Consequently, the flow path widths in the circumferential direction Dc of the inter-blade flow paths R1 and R2 differ only in the portion where the multiple blades 33G and the tongues 41s and 42s are close to each other. This also allows the frequency of noise generated in the gaps between the blades 33 and the tongues 41s and 42s to be dispersed without widening the gaps. This reduces noise at specific frequencies.

[0123] On the other hand, downstream in the exhaust gas flow direction, the plurality of moving blades 33G are arranged at equal intervals in the circumferential direction Dc. Therefore, the load acting on the plurality of moving blades 33G can be made uniform downstream in the exhaust gas flow direction.

[0124] (5) The turbocharger 10 according to the fifth aspect is the turbocharger 10 according to any one of aspects (1) to (4), wherein the turbine housing 40 includes a plurality of vortex flow paths 43, 44, which supply the exhaust gas to the impellers 31A to 31D from a plurality of different locations of the impellers 31A to 31D in the circumferential direction Dc.

[0125] Thus, in the turbocharger 10 having the exhaust gas inlet ports to the impellers 31A to 31D at different locations in the circumferential direction Dc, noise can be suppressed.

[0126] Industrial applicability

[0127] According to the above-described turbocharger, noise can be suppressed.

[0128] Description of Reference Numerals

[0129] 10: turbocharger;

[0130] 11: turbocharger body;

[0131] 12: bearing housing;

[0132] 13: Rotation axis;

[0133] 14A, 14B: bearings;

[0134] 20: compressor;

[0135] 21: compressor wheel;

[0136] 22: compressor housing;

[0137] 22r: flow path;

[0138] 30: Turbine;

[0139] 31A~31D: impeller;

[0140] 32: wheel hub;

[0141] 32a: hub center;

[0142] 32f, 32fa, 32fb: disk;

[0143] 33, 33G: moving blades;

[0144] 33f: leading edge;

[0145] 33r: posterior edge;

[0146] 33j: part;

[0147] 33k: root;

[0148] 40: turbine housing;

[0149] 41: peripheral wall;

[0150] 41s: tongue;

[0151] 42: middle wall;

[0152] 42s: tongue;

[0153] 43, 44: vortex flow path;

[0154] 43n, 44n: nozzle portion;

[0155] 45: exhaust part;

[0156] C: central axis;

[0157] Dc: circumferential direction;

[0158] Dr: radial;

[0159] G1: moving blade group (first moving blade group);

[0160] G2: moving blade group (second moving blade group);

[0161] G3~G5: moving blade group (the third moving blade group to the fifth moving blade group);

[0162] R, R1, R2, R11~R15: flow path between blades;

[0163] R21, R31: first inter-blade flow path;

[0164] R22, R32: second inter-blade flow path;

[0165] W1, W1', W1 1, W2: pressure change waveform;

[0166] f: specific frequency region;

[0167] ra: diameter size;

[0168] rb: diameter size;

[0169] θ1, θ2, θ11~θ15, θ21, θ22, θ31, θ32, θ41: included angle.

Claims

1. A turbocharger comprising: an impeller including a hub rotatably provided about a central axis, and a plurality of moving blades arranged radially outward of the hub at intervals in a circumferential direction about the central axis; a turbine housing disposed radially outside the impeller and forming a vortex flow path for causing the exhaust gas to swirl in the circumferential direction and guiding the exhaust gas toward the impeller radially inside; Among the plurality of inter-blade flow paths formed between the plurality of moving blades, at least one inter-blade flow path has a flow path width in the circumferential direction different from that of the other inter-blade flow paths. Among the plurality of inter-blade flow path portions, the hub in a first inter-blade flow path portion has a larger diameter than that in a second inter-blade flow path portion, and the second inter-blade flow path portion has a larger flow path width than the first inter-blade flow path portion.

2. The turbocharger according to claim 1, wherein: The plurality of moving blades include a first moving blade group arranged at equal intervals along the circumferential direction and a second moving blade group arranged at equal intervals along the circumferential direction. The respective moving blades of the second moving blade group are arranged to be shifted in phase in the circumferential direction with respect to the respective moving blades of the first moving blade group.

3. The turbocharger according to claim 1, wherein: The plurality of moving blades are arranged such that minimum flow path areas between adjacent blades in the circumferential direction are equal on the downstream side in the exhaust gas flow direction, and are arranged at unequal intervals in the circumferential direction on the upstream side in the exhaust gas flow direction.

4. The turbocharger according to claim 2, wherein: The plurality of moving blades are arranged such that minimum flow path areas between adjacent blades in the circumferential direction are equal on the downstream side in the exhaust gas flow direction, and are arranged at unequal intervals in the circumferential direction on the upstream side in the exhaust gas flow direction.

5. The turbocharger according to any one of claims 1 to 4, wherein: The turbine housing includes a plurality of the vortex flow paths, and the plurality of vortex flow paths supply the exhaust gas to the impeller from a plurality of different locations in the circumferential direction of the impeller.

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