Centrifugal compressor

Abstract

To suppress the degradation of compressor efficiency.SOLUTION: A centrifugal compressor is equipped with: a long blade (first blade) 110 that is provided on a compressor impeller (impeller) 10, has a first length from a leading edge to a trailing edge, and has the maximum blade thickness on the trailing edge side; a middle blade (second blade) 120 that is arranged separately from the first blade in a circumferential direction of the impeller, has a second length shorter than the first length from the leading edge to the trailing edge, and has the maximum blade thickness on the trailing edge side; and a short blade (third blade) 130 that is arranged separately from the first blade and the second blade in a circumferential direction of the impeller, has a third length shorter than the second length from the leading edge to the trailing edge, and has the maximum blade thickness on the trailing edge side.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a centrifugal compressor.

Background Art

[0002] Patent Document 1 discloses a compressor impeller provided with long blades, medium blades, and short blades.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a centrifugal compressor for a small flow rate, the size of each blade of the compressor impeller is smaller than that of a centrifugal compressor for a large flow rate. A clearance is provided between the shroud wall surface of the compressor housing and each blade of the compressor impeller. As the size of each blade of the compressor impeller becomes smaller, the ratio of the width of the clearance (clearance width) to the height of each blade (blade height) increases. As the ratio of the clearance width to the blade height increases, the compressor efficiency tends to decrease due to the influence of the air leaking through the clearance.

[0005] An object of the present disclosure is to provide a centrifugal compressor capable of suppressing a decrease in compressor efficiency.

Means for Solving the Problems

[0006] To solve the above problems, the centrifugal compressor of this disclosure comprises a housing in which an impeller is disposed; a first blade provided on the impeller, having a first length from the leading edge to the trailing edge and with the maximum blade thickness on the trailing edge side; a second blade disposed circumferentially with respect to the first blade, having a second length shorter than the first length from the leading edge to the trailing edge and with the maximum blade thickness on the trailing edge side; a third blade disposed circumferentially with respect to the first and second blades, having a third length shorter than the second length from the leading edge to the trailing edge and with the maximum blade thickness on the trailing edge side; and a housing formed in the housing that faces the first, second, and third blades with clearance in the radial or rotational axis direction of the impeller. ru shi The wing is provided with a rough wall, and the wing height of the trailing edge of the first wing is more than half the wing height of the leading edge of the first wing, the wing height of the trailing edge of the second wing is more than half the wing height of the leading edge of the second wing, the wing height of the trailing edge of the third wing is more than half the wing height of the leading edge of the third wing, and the wing height of the trailing edge of the third wing is more than twice the width of the clearance. Furthermore, the wing height of the trailing edges of the first, second, and third wings is set to be higher by the amount of the reduction in the flow path cross-sectional area between each wing due to the addition of the third wing to the first and second wings. ru.

[0007] The wing thickness of the first, second, and third wings may increase monotonically from the leading edge to the trailing edge.

[0010] The wing height of the trailing edge of the third wing may be greater than the distance between the tip-side wings of the adjacent first and second wings. [Effects of the Invention]

[0011] According to this disclosure, it is possible to suppress the decrease in compressor efficiency. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic cross-sectional view of a supercharger. [Figure 2]Figure 2 is a schematic front view of the compressor impeller of this embodiment. [Figure 3] Figure 3 is a schematic side view of the compressor impeller of this embodiment. [Figure 4] Figure 4 is a schematic cross-sectional view of a compressor housing and compressor impeller of a comparative example. [Figure 5] Figure 5 is a schematic cross-sectional view of the compressor housing and compressor impeller of this embodiment. [Figure 6] Figure 6 is a schematic diagram showing the shape of the end of the trailing edge TE of each blade in this embodiment. [Figure 7] Figure 7 is a graph showing the relationship between the wing thickness and the length in the meridional plane of each wing in this embodiment. [Modes for carrying out the invention]

[0013] An embodiment of this disclosure will be described below with reference to the attached drawings. The dimensions, materials, and other specific numerical values ​​shown in the embodiment are merely examples for the purpose of facilitating understanding and do not limit this disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to this disclosure are omitted from the illustrations.

[0014] Figure 1 is a schematic cross-sectional view of the turbocharger TC. In the following description, the direction of arrow L in Figure 1 will be described as the left side of the turbocharger TC. The direction of arrow R in Figure 1 will be described as the right side of the turbocharger TC. As shown in Figure 1, the turbocharger TC comprises a turbocharger body 1. The turbocharger body 1 includes a bearing housing 2, a turbine housing 4, and a compressor housing (housing) 6. The turbine housing 4 is connected to the left side of the bearing housing 2 by fastening bolts 3. The compressor housing 6 is connected to the right side of the bearing housing 2 by fastening bolts 5.

[0015] A bearing hole 2a is formed in the bearing housing 2. The bearing hole 2a penetrates the supercharger TC in the left-right direction. The bearing hole 2a accommodates a portion of the shaft 7. A bearing 8 is disposed in the bearing hole 2a. The bearing 8 is, for example, a pair of fully floating bearings. However, it is not limited to this, and the bearing 8 may be a semi-floating bearing or a rolling bearing, etc.

[0016] The shaft 7 is rotatably supported by a bearing 8. A turbine impeller 9 is provided at the left end of the shaft 7. The turbine impeller 9 is rotatably housed in the turbine housing 4. A compressor impeller (impeller) 10 is provided at the right end of the shaft 7. The compressor impeller 10 is rotatably housed in the compressor housing 6. Thus, the turbine impeller 9 is located inside the turbine housing 4, and the compressor impeller 10 is located inside the compressor housing 6.

[0017] An intake port 11 is formed in the compressor housing 6. The intake port 11 opens to the right of the supercharger TC. The intake port 11 is connected to an air cleaner (not shown). A diffuser passage 12 is formed by the opposing surfaces of the bearing housing 2 and the compressor housing 6. The diffuser passage 12 is annular. The diffuser passage 12 communicates with the intake port 11 radially inward via the compressor impeller 10. The diffuser passage 12 pressurizes the air.

[0018] The compressor housing 6 is formed with a compressor scroll flow path 13. The compressor scroll flow path 13 is annular. The compressor scroll flow path 13 is located, for example, radially outside the shaft 7 than the diffuser flow path 12. The compressor scroll flow path 13 communicates with an intake port of an engine (not shown) and the diffuser flow path 12. When the compressor impeller 10 rotates, air is sucked into the compressor housing 6 from the intake port 11. The sucked air is pressurized and accelerated in the process of flowing through the spaces between the blades of the compressor impeller 10. The pressurized and accelerated air is further pressurized in the diffuser flow path 12 and the compressor scroll flow path 13. The pressurized air is guided to the intake port of the engine.

[0019] Such a compressor housing 6 and a bearing housing 2 constitute a centrifugal compressor CC. In the present embodiment, an example in which the centrifugal compressor CC is mounted on a supercharger TC to will be described. However, the present invention is not limited to this, and the centrifugal compressor CC may be incorporated in a device other than the supercharger TC, or may be a single unit.

[0020] The turbine housing 4 is formed with a discharge port 14. The discharge port 14 opens to the left side of the supercharger TC. The discharge port 14 is connected to an exhaust gas purification device (not shown). The turbine housing 4 is formed with a communication flow path 15 and a turbine scroll flow path 16. The communication flow path 15 and the turbine scroll flow path 16 are annular. The turbine scroll flow path 16 is located, for example, radially outside the turbine impeller 9 than the communication flow path 15. The turbine scroll flow path 16 communicates with a gas inlet (not shown). Exhaust gas discharged from an exhaust manifold of an engine (not shown) is guided to the gas inlet. The communication flow path 15 communicates the turbine scroll flow path 16 and the discharge port 14 via the turbine impeller 9. The exhaust gas guided from the gas inlet to the turbine scroll flow path 16 is guided to the discharge port 14 via the communication flow path 15 and the turbine impeller 9. The exhaust gas guided to the discharge port 14 rotates the turbine impeller 9 in the process of flowing.

[0021] The rotational force of the turbine impeller 9 is transmitted to the compressor impeller 10 via the shaft 7. When the compressor impeller 10 rotates, the air is pressurized as described above. Thus, the air is guided to the intake port of the engine.

[0022] FIG. 2 is a schematic front view of the compressor impeller 10 of the present embodiment. FIG. 3 is a schematic side view of the compressor impeller 10 of the present embodiment. As shown in FIGS. 2 and 3, the compressor impeller 10 includes a hub 100, long blades (first blades) 110, middle blades 120 (second blades), and short blades (third blades) 130.

[0023] The hub 100 generally has a conical shape. The hub 100 is connected to the end of the shaft 7 (not shown) and rotates integrally with the shaft 7 about the rotation axis of the shaft 7.

[0024] Multiple long blades 110 are provided on the outer circumferential surface of the hub 100. The multiple long blades 110 are arranged at equal intervals in the circumferential direction of the hub 100. However, the arrangement is not limited to this, and the multiple long blades 110 may be arranged at unequal intervals in the circumferential direction of the hub 100. In the rotation axis direction of the shaft 7 (hereinafter simply referred to as the rotation axis direction), the length of the long blades 110 is longer than that of the medium blades 120 and short blades 130. The long blades 110 have a leading edge (hereinafter referred to as the leading edge LE) and a trailing edge (hereinafter referred to as the trailing edge TE). The length from the leading edge LE to the trailing edge TE of the long blade 110 (first length) is longer than the length from the leading edge LE to the trailing edge TE of the medium blades 120 and short blades 130. The long blades 110 are inclined in the circumferential direction. The inclination angle of the long blades 110 is greater than the inclination angle of the medium blades 120 and short blades 130. In this embodiment, the inclination angle of the long blade 110 with respect to the radial direction increases towards the inner diameter. However, it is not limited to this, and the long blade 110, medium blade 120, and short blade 130 do not have to be inclined in the circumferential direction; for example, they may extend along the radial direction. In the circumferential direction of the hub 100, the medium blade 120 and short blade 130 are included within the range from the leading edge LE to the trailing edge TE of the long blade 110.

[0025] Multiple intermediate blades 120 are provided on the outer circumferential surface of the hub 100. The intermediate blades 120 are spaced apart in the circumferential direction of the compressor propeller 10 relative to the long blades 110 and short blades 130. Multiple intermediate blades 120 are arranged at equal intervals in the circumferential direction of the hub 100. However, this is not limited to this arrangement, and multiple intermediate blades 120 may be arranged at unequal intervals in the circumferential direction of the hub 100. One intermediate blade 120 is positioned between a pair of circumferentially adjacent long blades 110. In the direction of rotation, the length of the intermediate blade 120 is shorter than that of the long blades 110 and longer than that of the short blades 130. The length of the intermediate blade 120 from the leading edge LE to the trailing edge TE (second length) is shorter than the length of the long blade 110 from the leading edge LE to the trailing edge TE. The length from the leading edge LE to the trailing edge TE of the medium blade 120 is longer than the length from the leading edge LE to the trailing edge TE of the short blade 130. The medium blade 120 is inclined in the circumferential direction. In this embodiment, the inclination angle of the medium blade 120 with respect to the radial direction increases towards the inner diameter. The inclination angle of the medium blade 120 is smaller than the inclination angle of the long blade 110 and larger than the inclination angle of the short blade 130. However, it is not limited to this, and the inclination angle of the medium blade 120 may be larger than the inclination angle of the long blade 110, and smaller than the inclination angle of the short blade 130. Also, the inclination angles of the long blade 110, medium blade 120, and short blade 130 may be equal to each other.

[0026] Multiple short blades 130 are provided on the outer circumferential surface of the hub 100. The short blades 130 are spaced apart from the long blades 110 and medium blades 120 in the circumferential direction of the compressor propeller 10. Multiple short blades 130 are arranged at equal intervals in the circumferential direction of the hub 100. However, this is not limited to this arrangement, and multiple short blades 130 may be arranged at unequal intervals in the circumferential direction of the hub 100. One short blade 130 is positioned between adjacent long blades 110 and medium blades 120 in the circumferential direction. In the direction of rotation axis, the length of the short blade 130 is shorter than that of the long blades 110 and medium blades 120. The length from the leading edge LE to the trailing edge TE of the short blade 130 (third length) is shorter than the length from the leading edge LE to the trailing edge TE of the long blades 110 and medium blades 120. The short blades 130 are inclined in the circumferential direction. The inclination angle of the short feather 130 is smaller than the inclination angles of the long feather 110 and the medium feather 120. However, it is not limited to this, and the inclination angle of the short feather 130 may be larger than the inclination angles of the long feather 110 and the medium feather 120.

[0027] Figure 4 is a schematic cross-sectional view of the compressor housing 6A and compressor impeller 10A of the comparative example. Components that are substantially the same as those in the supercharger TC of the above embodiment are denoted by the same reference numerals and their descriptions are omitted. As shown in Figure 4, the compressor impeller 10A of the comparative example includes long blades 210 and medium blades 220. Unlike the compressor impeller 10 of the above embodiment, the compressor impeller 10A of the comparative example does not have short blades 130.

[0028] The trailing edge TE of the long blade 210 is at the same position as the trailing edge TE of the medium blade 220 in the radial direction of the compressor propeller 10A. Here, "equal" includes both cases where they are perfectly equal and cases where they deviate from perfect equality within the range of tolerances (machining accuracy, assembly error, etc.). Furthermore, the height of the trailing edge TE of the long blade 210 (hereinafter simply referred to as the blade height) is equal to the blade height of the trailing edge TE of the medium blade 220.

[0029] The leading edge LE of the long blade 210 is located in a different position from the leading edge LE of the medium blade 220 in the direction of rotation axis. The leading edge LE of the long blade 210 is located closer to the intake port 11 (upstream of the intake) than the leading edge LE of the medium blade 220. Also, the blade height of the leading edge LE of the long blade 210 is higher than the blade height of the leading edge LE of the medium blade 220. The radial blade height of the leading edge LE of the long blade 210 and the medium blade 220 is higher than the blade height of the trailing edge TE of the long blade 210 and the medium blade 220 in the direction of rotation axis.

[0030] A shroud wall surface 250 is formed on the inner surface of the compressor housing 6A. The shroud wall surface 250 faces the long blades 210 and medium blades 220 in the radial direction. The shroud wall surface 250 is spaced radially or in the direction of the rotation axis from the long blades 210 and medium blades 220. In other words, a clearance CL is formed between the shroud wall surface 250 and the long blades 210 and medium blades 220.

[0031] Incidentally, centrifugal compressors for low flow rates have smaller individual blades on the compressor impeller compared to centrifugal compressors for high flow rates. Now, let's assume that the compressor housing 6A and compressor impeller 10A from the comparative example are applied to a centrifugal compressor for low flow rates. In this case, the minimum clearance amount that must be secured remains almost unchanged, and only the height of each blade 210 and 220 of the compressor impeller 10A (blade height) decreases. The smaller the size of each blade 210 and 220 of the compressor impeller 10A, the larger the ratio of the clearance width CL to the blade height. The larger the ratio of the clearance width to the blade height, the more easily the compressor efficiency decreases due to the influence of air leaking into the clearance CL.

[0032] Figure 5 is a schematic cross-sectional view of the compressor housing 6 and compressor impeller 10 of this embodiment. In Figure 5, the compressor housing 6A, long blades 210 and medium blades 220 of the comparative example are shown by dashed lines. In Figure 5, the compressor housing 6, long blades 110, medium blades 120 and short blades 130 of this embodiment are shown by solid lines.

[0033] As shown in Figure 5, the trailing edge TE of the long blade 110 is at the same position as the trailing edge TE of the medium blade 120 and the short blade 130 in the radial direction of the compressor propeller 10. The positions of the trailing edge TE of each blade 110, 120, and 130 in this embodiment are approximately the same as the positions of the trailing edge TE of each blade 210 and 220 in the comparative example. Furthermore, the blade heights of the trailing edge TE of the long blade 110, medium blade 120, and short blade 130 are all equal.

[0034] The leading edges LE of the long blade 110, medium blade 120, and short blade 130 are located at different positions in the direction of rotation axis. The leading edge LE of the long blade 110 is located closer to the intake port 11 (upstream of the intake) than the leading edges LE of the medium blade 120 and the short blade 130. The leading edge LE of the medium blade 120 is located closer to the intake port 11 than the leading edge LE of the short blade 130. In the comparative example, the leading edges LE of each blade 210 and 220 are located closer to the intake port 11 than the leading edges LE of each blade 110, 120, and 130 in this embodiment.

[0035] The wing height of the leading edge LE of the long blade 110 is higher than that of the leading edge LE of the medium blade 120. Also, the wing height of the leading edge LE of the medium blade 120 is higher than that of the leading edge LE of the short blade 130. The radial wing height of the leading edge LE of the long blade 110, medium blade 120, and short blade 130 is higher than the wing height in the rotational axis direction of the trailing edge TE of the long blade 110, medium blade 120, and short blade 130.

[0036] A shroud wall surface 150 is formed on the inner surface of the compressor housing 6. The shroud wall surface 150 faces each of the blades 110, 120, and 130 in the radial direction or in the direction of rotation. The shroud wall surface 150 is spaced apart from each of the blades 110, 120, and 130 in the radial direction or in the direction of rotation. A clearance CL is formed between the shroud wall surface 150 and each of the blades 110, 120, and 130. The shroud wall surface 150 faces each of the blades 110, 120, and 130 in the radial direction or in the direction of rotation via the clearance CL.

[0037] As shown in Figure 4, the blade height of the trailing edge TE of each blade 210 and 220 in the comparative example is less than half the blade height of the leading edge LE of each blade 210 and 220. When such a comparative example compressor impeller 10A is applied to a centrifugal compressor for low flow rates, the ratio of clearance width to blade height becomes large. When the ratio of clearance width to blade height becomes large, the airflow passing through the clearance is more likely to interfere with the main flow (hereinafter simply referred to as the main flow) circulating between each blade, and the compressor efficiency tends to decrease.

[0038] As shown in Figure 5, the blade height of the trailing edge TE of each blade 110, 120, and 130 in this embodiment is more than half the blade height of the leading edge LE of each blade 110, 120, and 130. This makes it possible to make the blade height of the trailing edge TE higher than that of each blade 210 and 220 in the comparative example. When such a compressor impeller 10 of this embodiment is applied to a centrifugal compressor for low flow rates, the ratio of clearance width to blade height becomes smaller compared to the comparative example. When the ratio of clearance width to blade height becomes smaller, the airflow passing through the clearance is less likely to interfere with the main flow between each blade, and the decrease in compressor efficiency can be suppressed.

[0039] Figure 6 is a schematic diagram showing the shape of the end of the trailing edge TE of each blade 110, 120, and 130 in this embodiment. In Figure 6, W1 is the clearance width between the shroud wall surface 150 and each blade 110, 120, and 130. In Figure 6, W2 is the width between the blades on the tip side CS of each blade 110, 120, and 130. In Figure 6, H1 is the blade height of the trailing edge TE of each blade 110, 120, and 130.

[0040] As shown in Figure 6, the shape of the trailing edge TE of each blade 110, 120, and 130 is roughly trapezoidal. The thickness of each blade 110, 120, and 130 decreases from the hub side HS towards the tip side CS.

[0041] The wing height H1 of the trailing edge TE of each wing (110, 120, and 130) is more than twice the clearance width W1. This allows for a smaller ratio of clearance width W1 to wing height H1 compared to the comparative example. By reducing the ratio of clearance width W1 to wing height H1, the adverse effects of the airflow through the clearance CL on the main flow can be reduced.

[0042] The blade height H1 of the trailing edge TE of each blade 110, 120, and 130 is greater than the width W2 between the blades of the tip side CS of adjacent blades 110, 120, and 130. This allows for a larger ratio of blade height length to circumferential length in the airflow path between each blade 110, 120, and 130. As a result, the ratio of clearance width W1 to blade height H1 can be reduced, minimizing the adverse effect of airflow through the clearance CL on the main flow.

[0043] Figure 7 is a graph showing the relationship between the blade thickness and the length in the meridional plane of each blade 110, 120, and 130 in this embodiment. In Figure 7, t0 represents the blade thickness of each blade 110, 120, and 130. CS110 represents the blade thickness of the tip-side CS of the long blade 110, CS120 represents the blade thickness of the tip-side CS of the medium blade 120, and CS130 represents the blade thickness of the tip-side CS of the short blade 130. HS110 represents the blade thickness of the hub-side HS of the long blade 110, HS120 represents the blade thickness of the hub-side HS of the medium blade 120, and HS130 represents the blade thickness of the hub-side HS of the short blade 130. In Figure 7, m2 is the length (total length) in the meridional plane from the leading edge LE to the trailing edge TE of the long blade 110. m is the length from the leading edge LE of each blade 110, 120, and 130 to any point.

[0044] As shown in Figure 7, on both the tip side CS and the hub side HS, the blade thickness t0 of the long blade 110, medium blade 120, and short blade 130 all increase monotonically from the leading edge LE towards the trailing edge TE. Thus, the position where each blade 110, 120, and 130 has its maximum blade thickness is not on the leading edge LE side, but on the trailing edge TE side. In other words, the position where each blade 110, 120, and 130 has its maximum blade thickness is at a dimensionless meridional position m / m² > 0.5. More preferably, the position where each blade 110, 120, and 130 has its maximum blade thickness is at a dimensionless meridional position m / m² > 0.7.

[0045] The compressor impeller 10 of this embodiment has short blades 130 added to the compressor impeller 10A of the comparative example. When short blades 130 are added to the compressor impeller 10A of the comparative example, the cross-sectional integral of the short blades 130 and the flow area between each blade become smaller.

[0046] In this embodiment, compared to the comparative example, the wing height H1 of the trailing edge TE of each blade 110, 120, and 130 is increased to maintain the flow area between each blade. In other words, in this embodiment, compared to the comparative example, the wing height H1 of the trailing edge TE of each blade 110, 120, and 130 is increased to compensate for the decrease in flow area due to the addition of the short blade 130.

[0047] Furthermore, in this embodiment, the position where each blade 110, 120, and 130 has its maximum blade thickness is located on the trailing edge TE side. Also, the blade thickness of each blade 110, 120, and 130 increases monotonically from the leading edge LE towards the trailing edge TE. As a result, the blade thickness t0 of the trailing edge TE of each blade 110, 120, and 130 can be made thicker than in the comparative example. In addition, in this embodiment, the blade height H1 of the trailing edge TE of each blade 110, 120, and 130 is increased by the amount by which the blade thickness of each blade 110, 120, and 130 is increased. This makes it possible to make the blade height H1 of the trailing edge TE of each blade 110, 120, and 130 even higher.

[0048] As described above, in this embodiment, compared to the comparative example, the width W2 between adjacent blades is narrowed by adding a short blade 130 and increasing the thickness of each blade 110, 120, and 130, and instead the blade height H1 is increased. As a result, the flow area between each blade is maintained, and the ratio of clearance width to blade height is reduced, thereby reducing the adverse effect that the airflow through the clearance has on the main flow.

[0049] Although one embodiment of the present disclosure has been described above with reference to the attached drawings, it goes without saying that the present disclosure is not limited to this embodiment. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present disclosure.

[0050] In the above embodiment, an example was described in which the blade thickness t0 of each blade 110, 120, and 130 increases monotonically from the leading edge LE to the trailing edge TE. However, the embodiment is not limited to this, and the blade thickness t0 of each blade 110, 120, and 130 does not have to increase monotonically from the leading edge LE to the trailing edge TE. For example, at a dimensionless meridional position m / m2 > 0.7, the blade thickness of each blade 110, 120, and 130 may decrease monotonically from the position of maximum blade thickness towards the trailing edge TE.

[0051] In the above embodiment, an example was described in which the wing height H1 of the trailing edge TE of each blade 110, 120, and 130 is more than twice the clearance width W1. However, the embodiment is not limited to this, and the wing height H1 of the trailing edge TE of each blade 110, 120, and 130 may be less than twice the clearance width W1.

[0052] In the above embodiment, an example was described in which the wing height H1 of the trailing edge TE of each blade 110, 120, and 130 is half or more of the wing height LE of each blade 110, 120, and 130. However, the embodiment is not limited to this, and the wing height H1 of the trailing edge TE of each blade 110, 120, and 130 may be less than half of the wing height LE of each blade 110, 120, and 130.

[0053] In the above embodiment, an example was described in which the wing height H1 of the trailing edge TE of each blade 110, 120, and 130 is greater than the width W2 between the wings of the tip side CS of each blade 110, 120, and 130. However, the embodiment is not limited to this, and the wing height H1 of the trailing edge TE of each blade 110, 120, and 130 may be smaller than the width W2 between the wings of the tip side CS of each blade 110, 120, and 130. [Explanation of symbols]

[0054] CC centrifugal compressor CL Clearance H1 Wing height LE Leading Edge TE Trailing Edge W1 Clearance width W2 width 6. Compressor housing (housing) 10 Compressor Impellers 110 Long feather (first feather) 120 Medium feather (2nd feather) 130 Short feather (3rd feather)

Claims

1. The housing in which the impeller is located, The impeller is provided with a first blade having a first length from the leading edge to the trailing edge, and the maximum blade thickness is on the trailing edge side, A second blade is positioned circumferentially away from the first blade, having a second length shorter than the first length from the leading edge to the trailing edge, and having its maximum blade thickness on the trailing edge side. The third blade is positioned spaced apart from the first and second blades in the circumferential direction of the impeller, has a third length shorter than the second length from the leading edge to the trailing edge, and has its maximum blade thickness on the trailing edge side, The housing is formed and the first blade, the second blade, and the third blade are separated by a clearance from the shroud wall surface which faces the impeller in the radial or rotational axis direction, Equipped with, The wing height of the trailing edge of the first blade is more than half the wing height of the leading edge of the first blade. The wing height of the trailing edge of the second blade is more than half the wing height of the leading edge of the second blade. The wing height of the trailing edge of the third blade is more than half the wing height of the leading edge of the third blade. The wing height of the trailing edge of the third wing is more than twice the width of the clearance. The wing height of the trailing edge of the first, second, and third blades is set to be higher by the amount of the decrease in the flow path cross-sectional area between each blade due to the addition of the third blade to the first and second blades. Centrifugal compressor.

2. The wing thickness of the first, second, and third wings increases monotonically from the leading edge to the trailing edge. The centrifugal compressor according to claim 1.

3. The wing height of the trailing edge of the third blade is greater than the distance between the tip-side wings of the adjacent first and second blades. A centrifugal compressor according to claim 1 or 2.

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