Outlet region of a compressor, a compressor having an outlet region of this type, and a supercharger having the compressor

Abstract

The present invention relates to an outlet region (10) of a compressor (20), particularly a radial or mixed-flow compressor. The outlet region (10) has a flow path (11) defined by a shroud-side sidewall (12) and a hub-side sidewall (13). The hub-side sidewall (13) has a contour in a compressor wheel outlet region (14), designed so that the cross-sectional area of ​​the flow path (11) decreases in the flow direction (1), passes through a minimum, and then increases again. In the compressor wheel outlet region (14), the flow path (11) has a length L extending from the compressor wheel outlet edge (4) to the diffuser vane inlet edge of a diffuser region (16). The diffuser region (16) is adjacent to the compressor wheel outlet region (14) and includes a number of diffuser vanes (17). The invention further relates to a compressor (20), in particular a radial or mixed flow compressor, having an outlet region (10) according to the invention, and to a turbocharger having the compressor (20).

Description

Technical Field

[0001] The present invention relates to compressors, in particular to the field of centrifugal compressors and mixed-flow compressors. More specifically, the present invention relates to the outlet region downstream of the compressor wheel and upstream of the diffuser region of such compressors.

Background Art

[0002] Currently, in order to improve the output of internal combustion engines, exhaust gas turbochargers equipped with turbines in the exhaust pipes of internal combustion engines and compressors upstream of the internal combustion engines are standardly used. Here, the exhaust gas of the internal combustion engine is expanded in the turbine. The work thus obtained is transmitted to the compressor by a shaft, and the compressor compresses the air supplied to the internal combustion engine. By using the energy of the exhaust gas to compress the air supplied to the combustion process of the internal combustion engine, it is possible to optimize the combustion process and the efficiency of the internal combustion engine.

[0003] Compressors with high discharge compressors wheels, in particular centrifugal compressors or mixed-flow compressors, have a large ratio of the compressor wheel inlet radius R1 to the compressor wheel outlet radius R2, for example R1 / R2 > 0.75. Generally, the flow is deflected radially in the impeller region or in the impeller and diffuser regions respectively, which leads to a large flow deflection and a large curvature of the shroud contour.

[0004] Furthermore, since generally a high pressure ratio is also required, in order to keep the centrifugal load below the limit of mechanical materials, it is desirable to design the hub of the compressor wheel to be thin. A thin-designed hub generally results in a small outlet angle (measured in the radial direction) of the compressor wheel hub contour.

[0005] When the meridian path in the diffuser is of a conventional design (for example, completely radial at the hub and having a pinch (continuous curvature) at the shroud), this initially leads to a significant narrowing of the flow cross-section downstream of the compressor wheel outlet. This generally leads to an increase in the Mach number at the diffuser inlet, specifically at the leading edge of the diffuser vanes. To avoid this, the diffuser, specifically the diffuser vanes, can be placed further downstream. Another improvement known from the prior art is, for example, a path recess on the contour of the hub. However, the known solutions have been found to have certain drawbacks with respect to efficiency, overall volume, and the cost of the compressor.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The object of the present invention is to provide an outflow region of a compressor, a compressor, and a turbocharger that is improved with respect to at least one of the drawbacks known from the prior art.

Means for Solving the Problems

[0007] To achieve the above object, there is provided an outflow region of a compressor according to independent claim 1, specifically a centrifugal compressor or a mixed-flow compressor. Further, there is provided a compressor having an outflow region according to the embodiments described herein, and a turbocharger having such a compressor.

[0008] Further aspects, advantages, and features of the present invention can be found in the dependent claims, the description, and the attached drawings.

[0009] In one aspect of the present invention, an outlet region of a compressor, in particular a centrifugal compressor or a mixed-flow compressor, is provided. The outlet region has a flow path defined by a shroud-side wall and a hub-side wall. The hub-side wall has a contour in the region of the compressor wheel outlet, and the contour is designed such that the cross-sectional area of the flow path decreases in the flow direction, passes through a minimum, and then increases again. In the region of the compressor wheel outlet, the flow path has a length L extending from the compressor wheel outlet edge to the diffuser vane inlet edge of the diffuser region. The diffuser region is adjacent to the region of the compressor wheel outlet and has a number of diffuser vanes.

[0010] Accordingly, an improved outlet region is advantageously provided over the prior art. In particular, due to the variability of the contour of the hub-side wall, an advantageous cross-sectional shape (decrease - minimum - increase) of the flow path can be achieved, so that the flow upstream of the diffuser region can be significantly decelerated without separation on the shroud side. Advantageously, the curvature on the shroud can first be checked and then the characteristics of the cross-sectional area can be adjusted by the hub contour (the contour of the hub-side wall). This enables a more compact design and higher efficiency. Accordingly, the risk of flow separation can be reduced by the outlet region according to the present invention, which has an advantageous effect on the efficiency of the compressor. In particular, the outlet region according to the present invention advantageously enables the compressor wheel outlet flow to be greatly decelerated within a compact installation space and made more uniform without having a tendency to cause early separation / destabilization during the slot ring.

[0011] According to a second aspect of the present invention, a compressor comprising a compressor wheel and an outlet region according to the embodiments described herein, in particular a centrifugal compressor or a mixed-flow compressor, is provided. Accordingly, a compressor with improved efficiency can be advantageously provided.

[0012] According to a third aspect of the present invention, a turbocharger having a compressor according to the embodiments described herein is provided, and an improved turbocharger over the prior art is advantageously provided.

[0013] The present invention will be described below with reference to exemplary embodiments shown in the drawings from which further advantages and modifications can be obtained.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0015] With reference to FIGS. 1 to 5, the outflow region 10 of the compressor 20 and the compressor 20 according to the present disclosure will be described. The compressor can be a radial flow compressor or a diagonal flow compressor. According to one embodiment that can be combined with other embodiments described herein, the outflow region 10 includes a flow path 11 defined by a shroud side wall 12 and a hub side wall 13. In the region 14 at the outlet of the compressor wheel, the hub side wall 13 has a profile designed such that in the flow direction 1, the cross-sectional area of the flow path, particularly the meridian cross-sectional area, decreases, passes through a minimum, and then increases again. In other words, the hub side wall 13 is designed such that in the flow direction 1, the flow cross-section of the flow path 11 gradually decreases, passes through a minimum, and widens again before entering the diffuser region 16. Specifically, the profile shape of the hub side wall 13 is designed such that in the flow direction 1, the distance from the opposite shroud side wall 12 decreases, passes through a minimum, and then increases again. In the region 14 at the outlet of the compressor wheel, the flow path 11 has a length L as shown in FIGS. 1 to 5. The length L of the flow path 11 extends from the outlet edge 4 of the compressor wheel to the inlet 5 to the diffuser region 16, specifically up to the diffuser vane inlet edge of the diffuser region 16. The diffuser region 16 is adjacent to the region 14 at the outlet of the compressor wheel and has a plurality of diffuser vanes 17.

[0016] Therefore, the flow downstream of the compressor wheel can be made more uniform first and then decelerated more significantly, reducing the risk of flow separation, which has a beneficial effect on the efficiency, overall volume, and cost of the compressor.

[0017] According to one embodiment that can be combined with other embodiments described herein, the contour of the hub side wall 13 has an S-shaped region 15. Specifically, the contour of the hub side wall has an S-shaped meridian contour shape between the compressor wheel outlet and the diffuser inlet. The S-shaped region 15 can be formed by, for example, at least three segments S1, S2, S3 as illustrated in FIG. 3. FIG. 4 shows an exemplary embodiment having four segments S1, S2, S3, S4. Each segment can be a line segment and / or a curve segment. Therefore, it should be understood that the S-shaped region 15 can be provided by a polygonal S-shaped contour. Alternatively, the S-shaped region 15 can also have a continuous contour shape. The contour shape can be tangent continuous or non-tangent continuous. For example, the S-shaped region 15 can have a right curvature and a left curvature in the flow direction as illustrated in FIGS. 1, 2 and 5. In other words, the S-shaped region 15 can have a convex curvature and a concave curvature facing the shroud side wall 12. Specifically, downstream of the compressor wheel outlet in the flow direction, the S-shaped region 15 first has a convex curvature facing the shroud side wall 12 and then has a concave curvature facing the shroud side wall 12. The shroud side wall 12 is typically designed to be exclusively convex with respect to the hub side wall 13 in the region of the compressor wheel outlet. Specifically, the shroud side wall 12 is designed to be exclusively convex with respect to the hub side wall 13 from the compressor wheel outlet to the inlet of the diffuser region.

[0018] According to one embodiment that can be combined with other embodiments described herein, as illustrated in FIGS. 1, 2 and 5, the hub side wall 13 has a continuous contour shape in the region 14 of the compressor wheel outlet. Alternatively or additionally, as illustrated in FIGS. 1 to 5, the shroud side wall 12 can have a continuous contour shape in the region 14 of the compressor wheel outlet. The shroud side wall 12 typically curves to the left in the flow direction 1.

[0019] According to one embodiment that can be combined with other embodiments described herein, the S-shaped region 15 is disposed at a position closer to the compressor wheel outlet edge 4 than the inlet 5 of the diffuser region. For example, the S-shaped region 15 can be disposed within 50% of the length L of the flow path 11 on the downstream side of the compressor wheel outlet edge. Typically, the point of change in the curvature of the hub side wall 13 provided by the S-shape is disposed at a position closer to the compressor wheel outlet edge 4 than the inlet 5 of the diffuser region. The position of the point of change in curvature is the position where the convex curvature of the hub side wall 13 facing the shroud side wall 12 joins the concave curvature of the hub side wall 13 facing the shroud side wall 12. Specifically, the position of the point of change in curvature is the position where the sign of the curvature changes. Specifically, the minimum portion of the flow path cross-section formed by the S-shaped region 15 of the flow path 11 can be disposed within 50% of the length L of the flow path 11 on the downstream side of the compressor wheel outlet edge. In other words, the minimum portion of the flow path cross-section is typically disposed at a position closer to the compressor wheel outlet edge 4 than the inlet 5 of the diffuser region.

[0020] According to one embodiment that can be combined with other embodiments described herein, the flow path 11 has a compressor wheel outlet cross-sectional area A2 and a diffuser inlet cross-sectional area A3, and the ratio A3 / A2 is selected from the range of 0.80 ≦ A3 / A2 ≦ 1.2, specifically from the range of 0.90 ≦ A3 / A2 ≦ 1.1. Typically, the compressor wheel outlet cross-sectional area A2 is a cylindrical surface (where the compressor wheel outlet edge extends parallel to the rotation axis) or a conical outer surface (where the compressor wheel outlet edge is inclined with respect to the rotation axis) on the downstream side of the compressor wheel outlet edge 4. Similarly, the diffuser inlet cross-section A3 can be a cylindrical surface (where the diffuser inlet edge extends parallel to the rotation axis) or a conical surface (where the diffuser inlet edge is inclined with respect to the rotation axis). In this regard, it is pointed out that the cross-sectional area of the flow path that decreases in the flow direction, passes through the minimum portion, and then increases again can be a cylindrical cross-sectional area and / or a conical cross-sectional area.

[0021] According to one embodiment that can be combined with other embodiments described herein, as illustrated in FIGS. 2 to 5, a clearance 3 (e.g., leakage flow opening) can be formed in the hub side wall 13, specifically at the compressor wheel outlet.

[0022] According to one embodiment that can be combined with other embodiments described herein, the minimum cross-sectional area in the flow direction of the flow path 11 is at a radial position r Min which exists, and this position is such that R2 < r Min ≦ R2 + 0.8×(R3 - R2), specifically R2 < r Min ≦ R2 + 0.6×(R3 - R2). R2 is the compressor wheel outlet radius, and R3 is the radial distance from the rotation axis 2 of the compressor wheel 21 to the inlet 5 to the diffuser region.

[0023] According to one embodiment that can be combined with other embodiments described herein, the ratio VQ of the minimum value of the cross-sectional area of the flow path 11 to the cross-sectional area A2 of the compressor wheel outlet can be selected from the range of 0.8 ≦ VQ < 1, specifically 0.9 ≦ VQ < 1.

[0024] According to one embodiment that can be combined with other embodiments described herein, the S-shaped region 15 has a point of change in curvature from a convex curvature facing the shroud side wall 12 to a concave curvature facing the shroud side wall 12, which is at a radius position r where R2 < r KW ≦ R2 + 0.8×(R3 - R2), specifically R2 < r KW ≦ R2 + 0.6×(R3 - R2). R2 is the compressor wheel outlet radius, and R3 is the radial distance from the rotation axis 2 of the compressor wheel 21 to the inlet 5 to the diffuser region. KW exists.

[0025] According to one embodiment that can be combined with other embodiments described herein, the convex curvature has a maximum curvature at the radial position r Kmax which is such that R2 < r Kmax ≦ R2 + 0.75×(R3 - R2), specifically R2 < rKmax It is selected from the range of ≦R2 + 0.5×(R3 - R2). The maximum curvature is understood to mean the maximum positive value of the curvature. According to one embodiment that can be combined with other embodiments described herein, the concave curvature has a minimum curvature at the radial position r Kmin such that R2 + 0.15×(R3 - R2) ≦ r Kmin < R3, specifically R2 + 0.25×(R3 - R2) ≦ r Kmin < R3 and is selected from the range. The minimum curvature value is understood to mean the maximum negative value of the curvature. In this regard, r Kmax where R2 < r Kmax ≦ R2 + 0.75×(R3 - R2) is selected, and r Kmin where R2 + 0.15×(R3 - R2) ≦ r Kmin < R3 is selected, r Kmax and r Kmin are typically selected such that r Kmax < r Kmin as pointed out.

[0026] It is pointed out that in this application, the cross-sectional area of the flow path is the meridian cross-sectional area of the flow path, specifically the cross-sectional area of the flow path extending in the direction normal to the main flow direction. The main flow direction extends along the center line between the shroud side wall 12 and the hub side wall 13.

[0027] According to another aspect of the present disclosure, a compressor 20 is provided that includes a compressor wheel 21 according to the embodiments described herein and an outflow region 10, specifically a radial flow compressor or a mixed flow compressor.

[0028] According to one embodiment that can be combined with other embodiments described herein, the compressor wheel 21 has a compressor wheel inlet radius R1 and a compressor wheel outlet radius R2. The ratio of the compressor wheel inlet radius R1 to the compressor wheel outlet radius R2 is typically selected from the range of 0.65 ≦ R1 / R2, specifically from the range of 0.7 ≦ R1 / R2.

[0029] According to one embodiment that can be combined with other embodiments described herein, the compressor comprises a diffuser region 16 disposed at a radial distance R3 from the rotation axis 2 of the compressor wheel 21. Typically, the ratio of the radial distance R3 to the compressor wheel outlet radius R2 is selected from the range of 1.05 ≦ R3 / R2 ≦ 1.30, and more particularly from the range of 1.10 ≦ R3 / R2 ≦ 1.25.

[0030] According to one embodiment that can be combined with other embodiments described herein, the contour of the hub side wall 13 comprises an S-shaped region 15 according to one of the embodiments described herein. As illustrated in FIG. 5, the S-shaped region 15 can have an end at a distance R S from the rotation axis 2 of the compressor wheel 21 in the flow direction. More particularly, the distance R S , the compressor wheel outlet radius R2, and the radial distance R3 of the diffuser region 16 from the rotation axis 2 of the compressor wheel 21 can be selected to satisfy the condition 0.4 ≦ (R S - R2) / (R3 - R2) ≦ 1.0. In this regard, it should be noted that the end of the S-shaped region 15 is a position where the concave curvature facing the shroud side wall 12 returns to zero.

[0031] In view of the present disclosure, according to another aspect, it is possible to provide a turbocharger comprising a compressor 20 according to the embodiments described herein, more particularly a radial flow compressor or a mixed flow compressor. In this regard, it should be noted that the features described in connection with exemplary embodiments of the radial flow compressor (FIGS. 2, 3 and 4) can be transferred to exemplary embodiments of the mixed flow compressor (FIGS. 1 and 5), and vice versa.

[0032] The embodiments described herein are particularly advantageous for high-discharge radial-flow or mixed-flow compressors. Compared with the prior art, the outflow of the compressor wheel is advantageously guided, made more uniform, and can be decelerated more significantly in a small installation space. When using a guide vane array (diffuser vanes) in the diffuser, it is possible to bring the guide vanes closer to the impeller or further reduce the Mach number level at the inlet edge of the diffuser vanes. The reduction of the Mach number and the uniformization of the diffuser vane flow lead to an improvement in efficiency. The possibility of uniformizing the flow and reducing the shroud-side contour curvature leads to an improvement in stability. By reducing the installation space, the manufacturing cost and the cost of the product can be reduced.

[0033] In other words, the embodiments described herein can have the following advantages. Continuous, specifically tangentially continuous, and discontinuous, specifically non-tangentially discontinuous hub contour shapes are possible, which reduces the risk of flow separation and is advantageous in terms of efficiency. The curvature of the shroud contour in the meridian diagram can be reduced without excessively reducing the flow area. Therefore, the risk of flow separation at the shroud can be reduced without the radial component of the flow being excessively accelerated on average. The surface shape in the diffuser (downstream of the compressor wheel) can be intentionally designed such that the momentum exchange on the shroud side is promoted (by reducing the shroud curvature and by the pinch region formed by the hub and shroud contours), and the flow at the hub (e.g., upstream of the leading edge of the diffuser vanes) is decelerated to the maximum extent. Therefore, the flow at the compressor wheel outlet can be significantly decelerated and made more uniform in a compact installation space without having a tendency for the flow to separate early and become unstable during throttling.

Explanation of Reference Numerals

[0034] 1 Flow direction 2 Rotation axis 3 Gap 4 Compressor wheel outlet edge 5 Inlet to the diffuser region 10 Outlet region 11 Flow path 12 Shroud side wall 13 Hub side wall 14 Region of the compressor wheel outlet 15 S-shaped contour 16 Diffuser region 17 Diffuser vane 20 Compressor 21 Compressor wheel R1 Compressor wheel inlet radius R2 Compressor wheel outlet radius R3 Radial distance from the axis of rotation to the inlet of the diffuser region R S Radial distance in the flow direction from the axis of rotation at the end of the S-shaped region S1, S2, S3, S4 Segments of the hub side wall contour

Claims

1. An outflow region (10) of a compressor (20), wherein the outflow region (10) has a flow path (11) defined by a shroud side wall (12) and a hub side wall (13), and in a region (14) of the compressor wheel outlet, the flow path extends from the compressor wheel outlet edge (4) to the diffuser vane inlet edge of the diffuser region (16), the diffuser region (16) communicates with the region (14) of the compressor wheel outlet, and has a number of diffuser vanes (17), the hub side wall (13) has an S-shaped contour (15) including a convex segment adjacent to the compressor wheel outlet edge and a concave segment adjacent to the outlet end of the convex segment in the flow direction of the flow from the compressor wheel outlet, the shroud side wall includes a contour that is convex from the compressor or the wheel outlet edge to the number of diffuser vanes, the contours of the hub side wall and the shroud side wall are configured such that the cross-sectional area of the flow path (11) decreases to a minimum and then increases in the flow direction (1), outflow region (10).

2. The outflow region (10) according to claim 1, wherein at least one of the hub side wall (13) and the shroud side wall (12) has a continuous contour shape in the region of the compressor wheel outlet (14).

3. The outflow region (10) according to claim 1, wherein the S-shaped contour (15) of the hub side wall is arranged closer to the compressor wheel outlet edge than to the inlet edge of the diffuser vane.

4. The outflow region (10) according to claim 1, wherein the flow path (11) has a compressor wheel outlet cross-sectional area A2 and a diffuser inlet cross-sectional area A3, and the ratio A3 / A2 is selected from the range of 0.80 ≦ A3 / A2 ≦ 1.

2.

5. The outflow region (10) according to any one of claims 1 to 4, wherein a gap (3) is formed in the hub side wall (13).

6. The minimum value of the cross-sectional area in the flow direction of the flow path (11) is R 2 < r Min ≤ R 2 + 0.8 × (R 3 − R 2 ) in the radial position r selected from the range, where R Min is the radius of the compressor wheel outlet from the rotation axis of the compressor wheel, and R 2 is the radial distance of the inlet (5) from the rotation axis (2) of the compressor wheel (21) to the diffuser region. The outflow region (10) according to any one of claims 1 to 5 3 .

7. Compressor wheel outlet cross-sectional area A 2 The ratio VQ of the minimum value of the cross-sectional area of the flow path (11) to the cross-sectional area A is selected from the range of 0.8 ≦ VQ < 1, and the outflow region (10) according to any one of claims 1 to 6.

8. The change point of the curvature from the convex segment to the concave segment is R 2 <r KW ≦R 2 +0.8(R 3 -R 2 ), and is located at a radial position r selected from the range of KW , where R 2 is the radius from the rotation axis of the compressor wheel at the outlet of the compressor wheel, and R 3 is the radial distance of the inlet (5) from the rotation axis (2) of the compressor wheel (21) to the diffuser region. The outflow region (10) according to any one of claims 1 to 7.

9. The convex segment is R 2 <r Kmax ≦R 2 +0.75×(R 3 -R 2 ) at a radial position r Kmax and the concave segment has a maximum curvature at R 2 +0.15×(R 3 -R 2 )≦r Kmin <R 3 A radial position r selected from the range min has minimum curvature at R 2 is the radius of the compressor wheel outlet from the rotation axis of the compressor wheel, and R 3 9. The outlet region (10) of claim 1, wherein x is the radial distance from the axis of rotation (2) of the compressor wheel (21) to an inlet (5) to the diffuser region.

10. The outflow region (10) according to any one of claims 1 to 9, wherein the cross-sectional area of the flow path is the meridian cross-sectional area of the flow path, and the main flow direction extends along the center line between the shroud side wall (12) and the hub side wall (13).

11. A compressor (20) having a compressor wheel (21) and an outflow region (10) according to any one of claims 1 to 10.

12. The compressor wheel (21) has a compressor wheel inlet radius R 1 and a radius R from the axis of rotation of the compressor wheel at the compressor wheel outlet 2 and a ratio R 1 / R 2 is selected from the range of 0.65 ≦ R 1 / R 2 The compressor (20) according to claim 11, wherein the compressor (20) is selected from the range of

13. The diffuser region (16) is arranged at a radial distance R from the rotation axis (2) of the compressor wheel (21). 3 It is arranged at the radius R 2 The ratio of the radial distance R to the radius R 3 is selected from the range of 1.05 ≦ R 3 / R 2 ≦ 1.30, and the compressor (20) according to claim 12.

14. The contour of the hub side wall (13) has a terminal end at a distance R from the rotation axis (2) of the compressor wheel (21) in the flow direction. S Rs, the radius R 2 , and the radial distance R of the diffuser region (16) from the rotation axis (2) of the compressor wheel (21) 3 are selected such that the condition 0.4 ≤ (R S − R 2 ) / (R 3 − R 2 ) ≤ 1.0 is satisfied. The compressor (20) according to claim 13.

15. A turbocharger having a compressor (20) according to any one of claims 11 to 14.

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