Impellers for compressors, compressors and turbochargers

Abstract

An impeller (10) for a centrifugal compressor or a mixed-flow compressor is described. The impeller (10) includes a plurality of main blades (11) and a plurality of splitter blades (12). The main blade hub-side contour (114) includes a first contour portion (C1) and a second contour portion (C2), and 0.4 ≦ (z IN SB -z SB ) / (z IN SB -z OUT MB )≦0.5; 0.4 ≦ (z IN MB -z IN SB ) / (z IN MB -z OUT MB )≦0.7; △R1 / △R IN MB ≧0.9; △R2 / △R IN SB ≧0.9; △R IN SB / △R IN MB ≦0.8 is applicable.

Description

[Technical Field]

[0001] Embodiments of the present disclosure relate to compressors, particularly centrifugal or mixed-flow compressors, and impellers for turbochargers, for example. Further embodiments of the present disclosure relate to compressors, particularly centrifugal or mixed-flow compressors, and turbochargers having such compressors. [Background technology]

[0002] Exhaust turbochargers are now used as a standard method for increasing the output of internal combustion engines, and have a turbine in the exhaust passage of the internal combustion engine and a compressor upstream of the engine. In this case, the exhaust gases of the internal combustion engine are expanded by the turbine. The work thus obtained is transmitted by a shaft to the compressor, which compresses the air supplied to the internal combustion engine. By using the energy of the exhaust gases to compress the air supplied to the combustion process of the internal combustion engine, the efficiency of the combustion process and the internal combustion engine can be optimized.

[0003] Compressors equipped with high-displacement compressor wheels, specifically centrifugal or mixed-flow compressors, have a high ratio of compressor wheel inlet radius R1 to compressor wheel outlet radius R2, for example, R1 / R2 > 0.62. Typically, the flow is radially deflected in the impeller region, or in both the impeller and diffuser regions, resulting in large flow deflection and a large curvature of the shroud profile. Furthermore, since high pressure ratios are usually required, it is desirable that the compressor wheel hub design be slim to keep the centrifugal load below the limits of the mechanical material. A slender hub design typically results in a small outlet angle (measured radially) of the compressor wheel hub profile.

[0004] There is a continuing demand for compressor impellers that improve mechanical high-cycle fatigue behavior, particularly the fatigue behavior of the impeller blades, without affecting the impeller's volumetric flow rate. One of the main challenges is to provide a compressor stage with a high specific volumetric flow rate, which requires designing the impeller throat area between adjacent impeller blades to be as large as possible. [Overview of the project] [Problems that the invention aims to solve]

[0005] Therefore, from the above perspective, there is a need for an improved compressor impeller that overcomes, at least partially, the problems of the prior art. [Means for solving the problem]

[0006] In view of the foregoing, an impeller for a centrifugal compressor or a mixed-flow compressor as described in independent claim 1 is provided. Furthermore, a compressor comprising an impeller according to an embodiment described herein, and a turbocharger comprising such compressor are provided. Further aspects, advantages, and features are evident from the dependent claims, the specification, and the accompanying drawings.

[0007] More specifically, according to one aspect of the present disclosure, an impeller for a centrifugal compressor or a mixed-flow compressor is provided. The impeller includes a plurality of main blades having a main blade inlet edge, a main blade outlet edge, a main blade shroud-side contour, and a main blade hub-side contour. Furthermore, the impeller includes a plurality of splitter blades having a splitter blade inlet edge and a splitter blade outlet edge. The splitter blade inlet edge is located downstream of the main blade inlet edge. The main blade hub-side contour is located at the axial position z of the main blade inlet edge in the main blade shroud-side contour. IN MB Therefore, the axial position z of the splitter blade inlet edge in the splitter blade shroud side contour. IN SB This includes the first contour portion up to [location]. Furthermore, the main blade hub side contour is located at the axial position z of the splitter blade inlet edge. IN SB From there, the axial reference position z of the splitter blade in the splitter blade shroud side contour. SB Includes the second contour portion up to the axial reference position z. SB This is the axial position z of the splitter blade inlet edge.IN SB and the axial position z of the main blade flow outlet edge in the main blade shroud side contour part OUT MB is centered within a tolerance T ≤ 10% therebetween. Here, a) 0.4 ≤ (z IN SB - z SB ) / (z IN SB - z OUT MB ) ≤ 0.5, and b) 0.4 ≤ (z IN MB - z IN SB ) / (z IN MB - z OUT MB ) ≤ 0.7 are applicable. The axial direction of the axial coordinate z is opposite to the inflow direction F of the fluid flowing in to rotate the impeller. The origin of the axial coordinate z is the last axial position of the main blade flow outlet edge in the inflow direction F. Further, regarding the first contour portion on the upstream side of the throat between adjacent main blades, the radial distance ΔR1 between the main blade hub side contour and the main blade shroud side contour, and the radial extension ΔR IN MB of the main blade flow outlet edge, the ratio is ΔR1 / ΔR IN MB ≥ 0.9. Further, regarding the second contour portion on the upstream side of the axial reference position z[[ID=3,5]] SB , the radial distance ΔR2 between the main blade hub side contour and the main blade shroud side contour, and the radial extension ΔR IN SB of the splitter blade flow inlet edge, the ratio is ΔR2 / ΔR IN SB ≥ 0.9. Further, the ratio of the radial extension ΔR IN SB of the splitter blade flow inlet edge and the radial extension ΔR IN MB of the main blade flow inlet edge is ΔR IN SB / ΔR IN MB ≤ 0.8.

[0008] Accordingly, an improved impeller for centrifugal or mixed-flow compressors is provided compared to the prior art. More specifically, the impeller according to the embodiments of the present disclosure provides a beneficial improved design that can maximize the impeller throat area while simultaneously improving the blade rigidity of the impeller blades, particularly the main blades.

[0009] According to another aspect of this disclosure, a compressor is provided which is particularly a centrifugal compressor or a mixed-flow compressor, including an impeller according to any embodiment described herein.

[0010] Further aspects of this disclosure provide a turbocharger including a compressor according to any embodiment described herein.

[0011] To allow for a detailed understanding of the features of this disclosure described above, a more specific description of this disclosure, which has been briefly summarized above, can be understood by referring to the embodiments. The accompanying drawings relate to embodiments of this disclosure. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic cross-sectional view of an impeller according to an embodiment described herein. [Figure 2] This is a schematic perspective side view of a portion of an impeller according to an embodiment described herein. [Figure 3] This is a schematic perspective front view of a portion of an impeller according to the embodiments described herein. [Modes for carrying out the invention]

[0013] Various embodiments of the present invention are described in detail below, with one or more of these embodiments shown in the drawings. Within the scope of the following description of the drawings, the same reference numerals refer to the same components. In general, only the differences relating to individual embodiments are described. Each embodiment is presented for illustrative purposes of the present disclosure and is not intended to limit the present disclosure. Furthermore, features illustrated or described as part of one embodiment can be used in other embodiments or in connection with other embodiments to obtain yet another embodiment. The present invention is intended to include such modifications and variations.

[0014] Within the scope of the following description of the drawings, the same reference numerals refer to the same or similar components. In general, only the differences relating to individual embodiments are described. Unless otherwise specified, the description of a part or aspect in one embodiment may also apply to the corresponding part or aspect in another embodiment.

[0015] An impeller 10 for a centrifugal or mixed-flow compressor according to an embodiment of the present disclosure will be described with reference to Figures 1 to 3.

[0016] According to embodiments that can be combined with other embodiments described herein, the impeller 10 includes a plurality of main blades 11 having a main blade inlet edge 111, a main blade outlet edge 112, a main blade shroud-side contour 113, and a main blade hub-side contour 114. Furthermore, the impeller 10 includes a plurality of splitter blades 12 having a splitter blade inlet edge 121 and a splitter blade outlet edge 122. The splitter blade inlet edge 121 is located downstream of the main blade inlet edge 111. Typically, the main blades 11 and splitter blades 12 are arranged circumferentially in an alternating manner around the central rotation axis 13 of the impeller, as illustrated in Figures 2 and 3.

[0017] Typically, the main blades of an impeller are curved blades and are mounted on the central hub of the impeller. Splitter blades are usually positioned between the main blades of the impeller. When in operation, the impeller rotates and compresses the fluid, such as air or gas, passing through the compressor. The main blades are usually designed with specific angles and shapes to efficiently accelerate and compress the fluid, increasing its pressure and density. The primary purpose of splitter blades is to guide and direct the fluid flow through the impeller blades, which improves the performance and efficiency of the compressor. In more detail, splitter blades work by dividing the incoming fluid into smaller flows, helping to reduce turbulence and improve the stability of the compressor.

[0018] In this disclosure, the “main blade flow inlet edge” can be understood as the leading edge of the main blade into which the airflow first flows, i.e., the edge of the main blade facing the fluid flow flowing into the compressor impeller. The inflow direction F is illustrated in Figure 1. Furthermore, Figure 1 shows the radial direction r and axial coordinate z.

[0019] Typically, the main blade inlet edge is designed to efficiently accelerate the incoming fluid flow and guide it into the blades, providing the energy necessary to compress the fluid as it passes through the compressor. Generally, the main blade inlet edge is designed to minimize airflow turbulence and separation, which can cause energy loss and reduce compressor efficiency.

[0020] In this disclosure, “splitter blade inlet edge” can be understood as the leading edge of the splitter blade into which the airflow first flows, i.e., the edge of the splitter blade facing the incoming fluid flow into the compressor impeller. This edge is designed so that the gas or airflow can be properly guided to the impeller blade, where it can be compressed and accelerated to produce a desired pressure and flow rate.

[0021] In this disclosure, “main blade outlet edge” can be understood as the trailing edge of the main blade from which the compressed fluid flow exits, i.e., the edge of the main blade that faces away from the inflowing fluid flow into the compressor impeller. Typically, the main blade outlet edge is designed to efficiently discharge the compressed fluid and smoothly redirect it toward the next stage of the compressor or the outlet. Typically, the main blade outlet edge is designed to minimize turbulence and pressure loss as the compressed fluid leaves the blade, which can cause energy loss and reduce the efficiency of the compressor.

[0022] In this disclosure, “splitter blade flow outlet edge” can be understood as the trailing edge of the splitter blade from which the compressed fluid flow exits, that is, the edge of the splitter blade that faces away from the incoming fluid flow into the compressor impeller.

[0023] In this disclosure, “main blade shroud side contour” can be understood as the outer edge, particularly the radial outer edge, of the main blade on the side facing the shroud, which is the outer casing of the compressor. Typically, the main blade shroud side contour is designed to reduce leakage of compressed fluid passing through the blade in order to improve the efficiency of the compressor.

[0024] In this disclosure, “main blade hub-side contour” can be understood as the outer shape or form of the inner edge, particularly the radial inner edge, of the main blade on the side facing the hub, which is the central portion of the compressor impeller. Typically, the hub-side contour is designed to optimize airflow and reduce energy loss within the compressor. More specifically, the hub-side contour is typically designed to keep the airflow smooth and uniform as it passes through the impeller blades.

[0025] In this disclosure, “Splitter blade shroud side contour” can be understood as the outer edge, particularly the radial outer edge, of the splitter blade facing the compressor shroud. “Splitter blade hub side contour” can be understood as the inner edge, particularly the radial inner edge, of the splitter blade facing the compressor hub.

[0026] Referring to Figure 1 as an example, the main blade hub side contour 114 is located at the axial position z of the main blade inlet edge 111 in the main blade shroud side contour 113. IN MB From there, the axial position z of the splitter blade inlet edge 121 in the splitter blade shroud side contour 123. IN SB This includes the first contour portion C1 up to [location]. In addition, the main blade hub side contour 114 is located at the axial position z of the splitter blade inlet edge 121 in the splitter blade shroud side contour 123. IN SB From the axial reference position z of the splitter blade 12 SB Includes the second contour portion C2 up to the axial reference position z. SB The axial position z of the splitter blade inlet edge 121 IN SB And the axial position z of the main blade outlet edge 112 in the main blade shroud side contour 113 OUT MB It lies in the middle within a tolerance T ≤ 10% between the two. The following conditions apply: a) 0.4 ≤ (z IN SB -z SB ) / (z IN SB -z OUT MB )≦0.5 and b) 0.4 ≤ (z IN MB -z IN SB ) / (z IN MB -z OUT MB )≦0.7 is applicable. Specifically, the condition of b) can be set as 0.55 ≦ (z IN MB -z IN SB ) / (z IN MB -z OUT MB ) ≦ 0.65. The axial direction of the axial coordinate z is opposite to the inflow direction F of the fluid flowing in to rotate the impeller. The origin of the axial coordinate z is the last axial position of the main blade flow outlet edge in the inflow direction F. Regarding the first contour portion C1 on the upstream side of the throat between adjacent main blades 11, the radial distance ΔR1 between the main blade hub side contour 114 and the main blade shroud side contour 113, and the radial extension ΔR IN MB of the main blade flow inlet edge 111, the ratio is ΔR1 / ΔR IN MB ≧ 0.9. Usually, the throat between adjacent main blades 11 is defined by the minimum flow cross-section between adjacent main blades 11. Specifically, in the case of an impeller, it should be understood that the throat refers to the narrowest part of the flow path of the impeller where the fluid is accelerated at high speed. Therefore, the term "throat between adjacent main blades" can be understood as the narrowest flow cross-section of the flow path between adjacent main blades of the impeller.

[0027] In addition, as exemplarily shown in FIG. 1, regarding the second contour portion C2 on the upstream side of the axial reference position z SB , the radial distance ΔR2 between the main blade hub side contour 114 and the main blade shroud side contour 113, and the radial extension ΔR IN SB of the splitter blade flow inlet edge 121, the ratio is ΔR2 / ΔR IN SB ≧ 0.9. Furthermore, the ratio of the radial extension ΔR IN SB of the splitter blade flow inlet edge 121 to the radial extension ΔR IN MB of the main blade flow inlet edge 111 is ΔR IN SB / ΔRIN MB The value is ≤ 0.8.

[0028] Accordingly, an improved impeller for centrifugal or mixed-flow compressors is provided compared to the prior art. In particular, the impeller according to the embodiments of the present disclosure can maximize the impeller throat area and at the same time provides a beneficial improved design with improved blade rigidity of the impeller blades, especially the main blades.

[0029] According to embodiments that can be combined with other embodiments described herein, the main blade hub side contour 114 in the combination of the first contour portion C1 and the second contour portion C2 includes at least one curvature change. Typically, the at least one curvature change includes a first curvature change from positive curvature to negative curvature and a second curvature change from negative curvature to further positive curvature.

[0030] In this disclosure, the "curvature change" of the contour can be understood as the rate at which the curvature of the contour changes at a given point. In other words, it represents how quickly the direction of the curvature of the contour changes when moving along the contour. Mathematically, the curvature change can be calculated by taking the second derivative of the contour equation with respect to the arc length.

[0031] In this disclosure, "positive curvature" of a contour can be understood as a situation in which the contour curves convexly at a given point. Conversely, "negative curvature" of a contour can be understood as a situation in which the contour curves concavely at a given point.

[0032] According to embodiments that can be combined with other embodiments described herein, the main blade hub side contour 114 in the combination of the first contour portion C1 and the second contour portion C2 includes an S-shaped contour portion. In this disclosure, the “S-shaped contour portion” can be understood as a contour portion consisting of two convex curves joined by a central concave curve.

[0033] It should be noted that the S-shaped impeller hub profile enables an increase in the impeller throat area by the possibility of minimizing the radius of the hub profile between the main blade leading edge and the splitter blade leading edge. Furthermore, including regions with negative curvature is beneficial, especially for increasing the blade rigidity downstream of the impeller throat region. Therefore, the impeller hub profile may appear in an S-shape placed on a basic curve with positive curvature.

[0034] Furthermore, it should be noted that the S-shaped hub profile has little impact on the optimal gas compression along the flow path because the rotational speed at the hub profile is generally low. Therefore, the influence on the compression performance can be ignored because flow separation is not as critical as in the sensitive blade tip region.

[0035] According to an embodiment that can be combined with other embodiments described herein, the position of the throat on the first contour portion C1 is a position where a plane providing a minimum flow cross-section between adjacent main blades 11 intersects the main blade hub side contour 114, which is particularly the negative pressure side surface of the main blade.

[0036] According to an embodiment that can be combined with other embodiments described herein, the following conditions (z IN MB -z TH ) / (z IN MB -z OUT SB )≧0.3 apply, where z TH is the position on the main blade hub side contour 114, where a plane providing a minimum flow cross-section between adjacent main blades 11 intersects the main blade hub side contour 114, particularly at the negative pressure side surface of the main blade.

[0037] In this disclosure, the “negative pressure side” of the main blade can be understood as the side or surface of the main blade facing the incoming fluid flow. The negative pressure side of the main blade has a technical function of drawing the fluid into the impeller. The negative pressure side is typically curved or contoured to optimize the fluid flow and minimize turbulence. In contrast, the “positive pressure side” of the main blade is the side or surface of the main blade that faces away from the incoming fluid flow and has a technical function of creating a pressure difference that drives the fluid out of the impeller. The positive pressure side is typically flatter and less contoured than the negative pressure side.

[0038] Accordingly, from the above viewpoint, it is understood that the embodiments described herein are beneficial in providing an improved compressor impeller that can be used, for example, in a centrifugal compressor or a mixed-flow compressor of a turbocharger. Accordingly, according to further aspects of the present invention, a compressor, in particular a centrifugal compressor or a mixed-flow compressor, including an impeller according to any embodiment described herein is provided. Another aspect of the present invention relates to a turbocharger including such a compressor. Accordingly, the present invention is beneficial in providing a compressor impeller, a compressor and a turbocharger that provide a high specific volume flow rate and are improved with respect to mechanical lifecycle fatigue behavior.

[0039] While the foregoing is directed toward embodiments of the present disclosure, other further embodiments of the present disclosure can be conceived without departing from its basic scope, which is determined by the following claims. [Explanation of Symbols]

[0040] 10 Impellers 11 Main Blades 111 Main blade inlet edge 112 Main blade outlet edge 113 Main blade shroud side contour 114 Main blade hub side contour 12 Splitter Blades 121 Splitter blade inlet edge 122 Splitter blade outlet edge 123 Splitter Blade Shroud Side Contour 124 Splitter Blade Hub Side Contour 13. Central axis of rotation 14 Throat C1 First contour portion of the main blade hub side contour C2 Second contour portion of the main blade hub side contour F Inflow direction z-axis coordinate r radial direction z IN MB Axial position of the main blade inlet edge z TH Axial position of the throat between adjacent main blades z IN SB Axial position of the splitter blade inlet edge z OUT MB Axial position of the main blade flow outlet edge ΔR IN MB Radial extension of the main blade inlet edge ΔR IN SB Radial extension of the splitter blade inlet edge Radial distance between the main blade hub side contour and the main blade shroud side contour in the first contour portion C1 of ΔR1 △R2 Radial distance between the main blade hub side contour and the main blade shroud side contour in the second contour portion C2

Claims

1. An impeller (10) for a centrifugal compressor or a mixed-flow compressor, A plurality of main blades (11) having a main blade inlet edge (111), a main blade outlet edge (112), a main blade shroud side contour (113), and a main blade hub side contour (114), A plurality of splitter blades (12) having a splitter blade inlet edge (121) and a splitter blade outlet edge (122) located downstream of the main blade inlet edge (111), Equipped with, The main blade hub side contour (114) is The axial position z of the main blade inlet edge (111) in the main blade shroud side contour (113) IN MB Therefore, the axial position z of the splitter blade inlet edge (121) in the splitter blade shroud side contour (123) IN SB The first contour portion (C1) up to, The axial position z of the splitter blade inlet edge (121) IN SB Therefore, the axial reference position z of the splitter blade (12) in the splitter blade shroud side contour (123) SB The second contour portion (C2) up to, Equipped with, The axial reference position z SB is at the center within a tolerance T ≦ 10% between the axial position z IN SB of the splitter blade flow inlet edge (121) and the axial position z OUT MB of the main blade flow outlet edge (112) in the main blade shroud side contour (113), where a)0.4≦(z IN SB -z SB ) / (z IN SB -z OUT MB )≦0.5 b)0.4≦(z IN MB -z IN SB ) / (z IN MB -z OUT MB )≦0.7 The following applies: The axial direction of the axial coordinate z is opposite to the inflow direction F of the fluid flowing in to rotate the impeller, and the origin of the axial coordinate z is the last axial position of the main blade outlet edge in the inflow direction F. With respect to the first contour portion (C1) on the upstream side of the throat between adjacent main blades (11), the radial distance ΔR between the main blade hub side contour (114) and the main blade shroud side contour (113) is... 1 And the radially extended portion △R of the main blade inlet edge (111) IN MB The ratio to is △R 1 / △R IN MB ≥ 0.9, The aforementioned axial reference position z SB With respect to the upstream second contour portion (C2), the radial distance △R between the main blade hub side contour (114) and the main blade shroud side contour (113) is 2 And the radially extended portion △R of the splitter blade inlet edge (121) IN SB The ratio to is △R 2 / △R IN SB ≥ 0.9, The radial extension portion △R of the splitter blade inlet edge (121) IN SB and the radially extended portion △R of the main blade inlet edge (111) IN MB The ratio to is △R IN SB / △R IN MB Impeller (10) ≤ 0.

8.

2. 0.55 ≤ (z IN MB -z IN SB ) / (z IN MB -z OUT MB The impeller (10) according to claim 1, to which ) ≤ 0.65 applies.

3. The impeller (10) according to claim 1 or 2, wherein the main blade hub side contour (114) within the combination of the first contour portion (C1) and the second contour portion (C2) includes at least one change in curvature.

4. The impeller (10) according to claim 3, wherein the at least one curvature change includes a first curvature change from positive curvature to negative curvature and a second curvature change from the negative curvature to a further positive curvature.

5. The impeller (10) according to any one of claims 1 to 4, wherein the main blade hub side contour (114) within the combination of the first contour portion (C1) and the second contour portion (C2) includes an S-shaped contour portion.

6. The impeller (10) according to any one of claims 1 to 5, wherein the main blade (11) and the splitter blade (12) are arranged in an alternating manner in the circumferential direction around the central rotation axis (13) of the impeller.

7. The impeller (10) according to any one of claims 1 to 6, wherein the throat between adjacent main blades (11) is defined by the minimum flow cross-section between adjacent main blades (11).

8. The position of the throat on the first contour portion (C1) is such that the plane providing the minimum flow cross section between adjacent main blades (11) intersects the main blade hub side contour (114), particularly on the main blade negative pressure side, according to any one of claims 1 to 7.

9. (z IN MB -z TH ) / (z IN MB -z OUT SB ) ≥ 0.3 is applied, z TH The impeller (10) according to any one of claims 1 to 8, wherein the plane providing the minimum flow cross section between adjacent main blades (11) intersects the main blade hub-side contour (114) particularly on the main blade negative pressure side.

10. A compressor, particularly a centrifugal compressor or a mixed-flow compressor, comprising an impeller according to any one of claims 1 to 9.

11. A turbocharger comprising the compressor described in claim 10.

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