Impeller, compressor, compressor unit and heat pump system

Abstract

The application relates to an impeller, a compressor, a compressor set and a heat pump system. The impeller is applied to the compressor, and the impeller comprises a hub and a first blade group, a second blade group and a third blade group arranged on the hub; wherein the first blade group comprises a plurality of first blades, the second blade group comprises a plurality of second blades, and the third blade group comprises a plurality of third blades; along the circumference of the hub, one second blade is arranged between every two adjacent first blades, and one third blade is arranged between every first blade and second blade; the length of the first blade, the length of the second blade and the length of the third blade sequentially decrease. The length difference between the first blade, the second blade and the third blade can form a flow space for the working medium to flow around the different blade parts, so that the occlusion of the working medium by the blade channel can be reduced under the condition that the number of blades is dense, the compression efficiency of the impeller is improved, and the efficiency of the compressor is improved.

Description

Technical Field

[0001] This application relates to the field of compressor technology, and in particular to an impeller, compressor, compressor unit and heat pump system. Background Technology

[0002] Heat pump systems are highly efficient energy-saving systems. Their use effectively recovers low-grade energy, improves energy utilization efficiency, reduces the consumption of high-grade energy, and alleviates the pressure of the energy crisis. Therefore, heat pump systems have been widely used in social production and daily life. Currently, high-temperature heat pump technology using water as the working fluid and vapor recompression technology are among the fastest-growing energy-saving technologies in recent years. However, the compressors in these technologies cannot achieve efficient water compression, resulting in low compressor efficiency. Summary of the Invention

[0003] Therefore, it is necessary to address the problem that compressors in related technologies cannot achieve efficient water compression, resulting in low compressor efficiency, and to provide an impeller, compressor, compressor unit, and heat pump system that can achieve efficient water compression and improve compressor efficiency.

[0004] In a first aspect, an impeller is provided for use in a compressor, the impeller including a hub and a set of blades disposed on the hub, the set of blades including at least a first set of blades, a second set of blades and a third set of blades;

[0005] The first blade group includes a plurality of first blades, the second blade group includes a plurality of second blades, and the third blade group includes a plurality of third blades; along the circumference of the hub, all the first blades, all the second blades, and all the third blades are arranged alternately at intervals.

[0006] The lengths of the first blade, the second blade, and the third blade decrease sequentially.

[0007] In one embodiment, along the circumference of the hub, a second blade is provided between every two adjacent first blades, and a third blade is provided between each first blade and a second blade.

[0008] In one embodiment, the length L1 of the first blade and the length L3 of the third blade satisfy: 50% ≤ L3 / L1 ≤ 60%; and / or

[0009] The lengths L1 and L2 of the first blade satisfy the following condition: 70% ≤ L2 / L1 ≤ 80%.

[0010] In one embodiment, the distances between the leading edges of the first blade, the second blade, and the third blade and the leading edge of the hub gradually decrease along the radial direction of the impeller.

[0011] In one embodiment, the ratio of the root thickness to the tip thickness of the first, second, and third blades is 2.5 to 3.

[0012] In one embodiment, the leading edge cross-sectional shape of the first blade, the second blade, and the third blade is semi-elliptical.

[0013] In one embodiment, the first blade and the second blade are both backward-curved blades, and the third blade is a radially straight blade.

[0014] In one embodiment, the outlet mounting angle between the first blade and the second blade ranges from 30° to 45°.

[0015] In one embodiment, the impeller is made of titanium alloy.

[0016] Secondly, a compressor is also provided, characterized in that it includes the impeller in any of the above embodiments.

[0017] In one embodiment, the compressor further includes a primary impeller, a secondary impeller, a motor stator, and a motor rotor;

[0018] The motor stator is located on the outside of the motor rotor along the circumference of the motor rotor, and the first-stage impeller and the second-stage impeller are located at opposite ends of the motor rotor; wherein, both the first-stage impeller and the second-stage impeller are impellers.

[0019] Thirdly, a compressor unit is also provided, comprising two compressors as described in any of the above embodiments, the two compressors being connected sequentially along the axial direction.

[0020] Fourthly, a heat pump system is also provided, characterized in that it includes a compressor as described in any of the above embodiments; or

[0021] The heat pump system includes the compressor unit in any of the above embodiments.

[0022] In one embodiment, the heat pump system includes a compressor unit, and each compressor can be controlled independently.

[0023] The aforementioned impeller, compressor, compressor unit, and heat pump system, by having a first blade group, a second blade group, and a third blade group on the impeller, with the lengths of the first blade in the first blade group, the second blade in the second blade group, and the third blade in the third blade group decreasing sequentially, can form a flow space for the working fluid to flow around the different blade sections due to the difference in length. This reduces the obstruction of the working fluid in the blade passage even when the number of blades is dense, improves the compression efficiency of the impeller, and thus improves the efficiency of the compressor. Attached Figure Description

[0024] Figure 1This is a schematic diagram of the impeller structure in one or more embodiments.

[0025] Figure 2 for Figure 1 The impeller is shown in front view.

[0026] Figure 3 for Figure 1 The impeller shown is a side view.

[0027] Figure 4 This is a diagram showing the fluid flow velocity when the first blade is a backward-curved blade.

[0028] Figure 5 This is a diagram showing the fluid flow velocity when the third blade is a radial blade.

[0029] Figure 6 This is a schematic cross-sectional view of the compressor in one or more embodiments.

[0030] Explanation of reference numerals in the attached figures:

[0031] Impeller 100;

[0032] Wheel hub 10;

[0033] Front edge 11;

[0034] First leaflet 20;

[0035] First leading edge 21, first leaf root 22, first leaf tip 23;

[0036] The second blade is 30;

[0037] Second leading edge 31, second leaf root 32, second leaf tip 33;

[0038] The third blade is 40;

[0039] Third leading edge 41, third leaf root 42, third leaf tip 43;

[0040] Compression channel 50;

[0041] Compressor 200;

[0042] First-stage impeller 210;

[0043] Secondary impeller 220;

[0044] Motor stator 230;

[0045] Motor rotor 240;

[0046] Radial gas bearing 250. Detailed Implementation

[0047] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0048] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must include a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0049] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0050] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0051] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0052] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0053] With rapid socio-economic development and ever-increasing material demands, energy consumption is escalating, and future energy shortages will be a major global problem. Issues such as ozone layer depletion, global warming, glacial melting, and rising sea levels urgently need to be addressed. Vigorously promoting green and energy-saving technologies to reduce energy consumption and pollution in production and daily life is a crucial means to overcome the energy crisis and reduce environmental pollution, and an inevitable choice for sustainable development in today's society.

[0054] Heat pump systems are highly efficient energy-saving systems that effectively recover low-grade energy, improve energy utilization efficiency, reduce the consumption of high-grade energy, and alleviate the pressure of the energy crisis. Therefore, heat pump systems have been widely used in social production and daily life. However, heat pump systems also face the challenge of selecting the appropriate working fluid and compressor. Given the serious ozone layer depletion and greenhouse effect of synthetic chlorofluorocarbons (CFCs), limiting their use and development prospects, heat pump systems require more careful selection of working fluids and compressors. This significantly restricts the application of heat pump systems in various aspects of production and daily life. Therefore, researching and using new, efficient, green, environmentally friendly, and readily available working fluids and compressors, as well as improving the temperature range of heat pump systems in practical applications, have become problems that the heat pump system industry needs to solve.

[0055] Currently, high-temperature heat pump technology using water as the working fluid and vapor recompression technology are energy-saving technologies that have developed rapidly in recent years. However, the compressors in these technologies cannot achieve efficient compression of water, resulting in low compressor efficiency.

[0056] Analysis shows that, generally, the more blades a compressor impeller has, the stronger its work output. However, when water is used as the working fluid, compression becomes difficult. Therefore, increasing the number of impeller blades is necessary to increase pressure, but this results in denser blade arrangement on the impeller inlet side.

[0057] The dense blades present both challenges in processing and the risk of water blockage at the inlet, thus hindering efficient water compression and resulting in low compressor efficiency.

[0058] This application provides an impeller 100 that enables efficient compression of water when water is used as the working fluid, thereby improving the efficiency of the compressor.

[0059] See Figures 1-3 An impeller 100 provided in one embodiment of this application is applied to a compressor 200. The impeller 100 includes a hub 10 and a blade assembly disposed on the hub. Specifically, the compressor 200 is a centrifugal compressor.

[0060] The blade group includes at least a first blade group, a second blade group, and a third blade group. The first blade group includes multiple first blades 20, the second blade group includes multiple second blades 30, and the third blade group includes multiple third blades 40. Along the circumference of the hub 10, all the first blades 20, all the second blades 30, and the third blades 40 are arranged alternately at intervals.

[0061] Hereinafter, the first blade 20, the second blade 30, and the third blade 40 are collectively referred to as blades. It should be noted that a compression channel 50 is formed between each adjacent blade and the hub 10. For example, a compression channel 50 is formed between each first blade 20 and a third blade 40, and another compression channel 50 is formed between each second blade 30 and a third blade 40.

[0062] The lengths of the first blade 20, the second blade 30, and the third blade 40 decrease sequentially.

[0063] The blade length refers to the length along the blade's curvature from its leading edge to its trailing edge. It's important to note that the leading edge refers to the edge of the blade located on the inlet side of the impeller 100. During impeller 100 rotation, the working fluid flows from the inlet side to the outlet side, that is, from the side closer to the center of the impeller 100 towards its edge. The trailing edge of the blade is positioned opposite the leading edge, specifically referring to the edge of the blade located on the outlet side of the impeller 100. In practical applications, when measuring the blade length, the midpoint of the leading edge can be taken first, followed by the midpoint of the trailing edge. The length from the midpoint of the leading edge to the midpoint of the trailing edge along the blade's curvature is the blade length.

[0064] Since at least a first blade group, a second blade group, and a third blade group are provided on the impeller 100, and the lengths of the first blade 20 of the first blade group, the second blade 30 of the second blade group, and the third blade 40 of the third blade group decrease sequentially along the axial direction of the impeller 100, the difference in length can form a flow space for the working fluid to flow around the different blade portions. This reduces the obstruction of the working fluid by the blade passage when the number of blades is dense, improves the compression efficiency of the impeller 100, and thus improves the efficiency of the compressor 200.

[0065] Regarding the specific arrangement of the blades, in some embodiments of this application, all the first blades 20 are arranged at equal intervals along the circumference of the hub 10, all the second blades 30 are arranged at equal intervals, and all the third blades 40 are arranged at equal intervals.

[0066] The equidistant arrangement allows the entire impeller 100 structure to be centrally symmetrical, ensuring smooth operation of the impeller 100 during rotation.

[0067] Furthermore, along the circumference of the hub 10, a second blade 30 is provided between every two adjacent first blades 20, and a third blade 40 is provided between each first blade 20 and the second blade 30.

[0068] This arrangement expands the flow space between the two longest adjacent first blades 20, further reducing the obstruction of the working fluid by the blade passage.

[0069] This arrangement also allows the total number of all first leaves 20 and all second leaves 30 to be odd, while the total number of all third leaves 40 is even.

[0070] In some other embodiments, all the first blades 20, all the second blades 30, and the third blade 40 are arranged alternately along the circumference of the hub 10. That is, if you start counting clockwise from the first blade 20 along the circumference of the hub 10, the next blades are the second blade 30, the third blade 40, and then another first blade 20, another second blade 30, another third blade 40, and so on.

[0071] In some embodiments, along the radial direction of the impeller 100, the distances between the first leading edge 21 of the first blade 20, the second leading edge 31 of the second blade 30, and the third leading edge 41 of the third blade 40 and the leading edge 11 of the hub 10 gradually decrease.

[0072] When the impellers of impeller 100 are densely packed, the distance between the blades on the inlet side is closer. Therefore, based on the principle that the lengths of the first blade 20 of the first blade group, the second blade 30 of the second blade group, and the third blade 40 of the third blade group decrease sequentially along the axial direction of impeller 100, the distances between the first leading edge 21 of the first blade 20, the second leading edge 31 of the second blade 30, and the third leading edge 41 of the third blade 40 and the leading edge 11 of the hub 10 are gradually reduced. This can reduce the blockage of the working fluid on the inlet side and make the compression efficiency of impeller 100 higher.

[0073] Optionally, along the radial direction of the impeller 100, the first leading edge 21 of the first blade 20 extends to intersect with the leading edge 11 of the hub 10, the third leading edge 41 of the third blade 40 intersects with the middle position of the hub 10, and the second leading edge 31 of the second blade 30 intersects with the hub 10 at a position between the two mentioned above, that is, between the leading edge 11 of the hub 10 and the middle position of the hub 10.

[0074] In some embodiments, along the axial direction of the impeller 100, the length L1 of the first blade 20 and the length L3 of the third blade 40 satisfy: 50% ≤ L3 / L1 ≤ 60%.

[0075] In this way, a larger flow space can be formed in the part where the third blade 40 and the first blade 20 have a length difference, allowing the working medium to flow, and further reducing the blockage of the working medium in the blade passage.

[0076] In some embodiments, along the axial direction of the impeller 100, the length L1 of the first blade 20 and the length L2 of the second blade 30 satisfy: 70% ≤ L2 / L1 ≤ 80%.

[0077] In this way, on the one hand, the impact of the second blade 30 on the working fluid blockage is reduced, and on the other hand, a certain length of the compression channel 50 is maintained, thereby improving the compression performance of the working fluid.

[0078] In some embodiments, 50% ≤ L3 / L1 ≤ 60%, and 70% ≤ L2 / L1 ≤ 80%. In this way, a larger flow space can be formed between the blades for the working fluid to flow, while maintaining a certain length of the compression channel 50, thereby improving the compression performance of the working fluid.

[0079] In order to enhance the structural strength of the blades, in the embodiments of this application, the root thickness of the first blade 20, the second blade 30 and the third blade 40 are all greater than the tip thickness.

[0080] It should be noted that the blade root refers to the side edge connected to the hub 10, and the blade tip refers to the side edge opposite to the blade root.

[0081] Specifically, the thickness of the first leaf root 22 of the first leaf 20 is greater than the thickness of the first leaf tip 23 of the first leaf 20, the thickness of the second leaf root 32 of the second leaf 30 is greater than the thickness of the second leaf tip 33 of the second leaf 30, and the thickness of the third leaf root 42 of the third leaf 40 is greater than the thickness of the third leaf tip 43 of the third leaf 40.

[0082] Optionally, the ratio of the thickness at the base to the thickness at the tip of the first leaf 20, the second leaf 30, and the third leaf 40 is 2.5 to 3.

[0083] In this way, the blade roots of the first blade 20, the second blade 30 and the third blade 40 can be reliably connected to the hub 10, thereby improving the overall structural strength of the impeller 100.

[0084] In some embodiments, the leading edge cross-sectional shape of the first blade 20, the second blade 30, and the third blade 40 is semi-elliptical.

[0085] The cross-sectional shape of the leading edge of the blade referred to here is the shape of the cross section taken along the width direction of the blade.

[0086] By setting the leading edge cross-sectional shape of the first blade 20, the second blade 30, and the third blade 40 to be semi-elliptical arc, the first blade 20, the second blade 30, and the third blade 40 can conform to the flow characteristics of airfoil blades, optimize the inlet side conditions of the impeller 100, reduce the loss of working fluid in the flow, and improve the compression efficiency.

[0087] In some embodiments, the first blade 20 and the second blade 30 are both backward-curved blades, and the third blade 40 is a radial blade.

[0088] Back-curved blades refer to blades that are curved away from the rotation direction of the impeller 100 from the inlet side to the outlet side. Radial blades refer to blades whose outlet direction is consistent with the radial direction of the impeller 100.

[0089] Back-curved blades have weak workmanship but high energy efficiency, while radial blades have strong workmanship but low energy efficiency. Therefore, the first blade 20 and the second blade 30 are both back-curved blades, and the third blade 40 is a radial blade. This can combine the advantages of both types of blades, which can not only increase the workmanship of the impeller 100, but also improve energy efficiency.

[0090] See Figure 4 and Figure 5It should be noted that the work h done by the impeller 100 on the working fluid is directly proportional to the circumferential velocity C2u on the outlet side of the impeller 100. When designing the compressor 200, the pressure ratio follows Euler's equation: h = C2u * U2, where U2 is the circumferential velocity on the outlet side. It is evident that the work capacity of the radial blades is greater than that of the backward-curved blades. Therefore, using a third radial blade 40 between the longer first blade 20 and the second blade 30 can increase the work capacity of the impeller 100 and improve its pressure ratio, i.e., its energy efficiency. Figure 4 and Figure 5 It should also be noted that W2 is the relative velocity on the exit side, C2 is the absolute velocity on the exit side, and C2r is the radial velocity component on the exit side.

[0091] Specifically, in the embodiments of this application, the outlet installation angle β2A of the first blade 20 and the second blade 30 ranges from 30° to 45°. The outlet installation angle β2A of the third blade 40 is 90 degrees.

[0092] This results in a large backward bending angle for the first blade 20 and the second blade 30, which effectively increases the reaction degree of the impeller 100. This allows the increase in working fluid pressure to be mainly completed in the impeller 100, reducing the kinetic energy of the diffuser entering the compressor and lowering the flow loss of downstream components after the impeller 100, thereby improving the overall efficiency of the compressor.

[0093] In some embodiments, the impeller 100 is made of titanium alloy. The titanium alloy impeller 100 is high in strength, lightweight, and highly corrosion-resistant, making it suitable for high-speed operation.

[0094] In the embodiments of this application, the blade group of the impeller 100 includes only the first blade group, the second blade group, and the third blade group. In other embodiments, the blade group of the impeller 100 may also include a fourth blade group, etc., wherein the fourth blade group includes multiple fourth blades, and the length of the fourth blades is different from the length of the first blade 20, the length of the second blade 30, and the length of the third blade 40.

[0095] like Figure 6 As shown, based on the same inventive concept, this application also provides a compressor 200, including the impeller 100 in any of the above embodiments.

[0096] Since at least a first blade group, a second blade group, and a third blade group are provided on the impeller 100, and the lengths of the first blade 20 of the first blade group, the second blade 30 of the second blade group, and the third blade 40 of the third blade group decrease sequentially along the axial direction of the impeller 100, the difference in length can form a flow space for the working fluid to flow around the different blade portions. This reduces the obstruction of the working fluid by the blade passage when the number of blades is dense, improves the compression efficiency of the impeller 100, and thus improves the efficiency of the compressor 200.

[0097] Furthermore, the compressor 200 includes a primary impeller 210, a secondary impeller 220, a motor stator 230, and a motor rotor 240. The motor stator 230 is disposed circumferentially on the outer side of the motor rotor 240, and the primary impeller 210 and the secondary impeller 220 are disposed opposite to each other at both ends of the motor rotor 240. The primary impeller 210 and the secondary impeller 220 are both impellers 100 in any of the above embodiments.

[0098] The primary impeller 210 and the secondary impeller 220 are positioned opposite each other at both ends of the motor rotor 240, which helps to reduce the axial force during the operation of the compressor 200 and make the axial force uniform.

[0099] Optionally, the compressor 200 uses a synchronous permanent magnet variable frequency motor.

[0100] Furthermore, the compressor 200 also includes two radial gas bearings 250, one of which is sleeved on both ends of the motor rotor 240 and located between the first-stage impeller 210 and the second-stage impeller 220.

[0101] This arrangement of the radial gas bearing 250 is beneficial for uniform force distribution on the radial gas bearing 250, while ensuring uniform stiffness of the motor rotor 240, and reducing the problem of excessive vibration caused by excessive cantilever of the first-stage impeller 210 and the second-stage impeller 220.

[0102] Furthermore, the compressor 200 also includes an axial bearing located on the side of the first-stage impeller 210 facing the second-stage impeller 220 and mounted on the motor rotor 240.

[0103] By installing axial bearings, the motor rotor 240 can run smoothly axially.

[0104] Based on the same inventive concept, this application also provides a compressor unit, including two compressors 200 as described in the above embodiments, the two compressors 200 being connected sequentially along the axial direction.

[0105] Since a single compressor 200 has limited pressure-boosting capacity, when the heat pump system operates at high outlet water temperatures, a dual-compressor configuration with two compressors 200 connected together is used. This allows for liquid injection cooling after each impeller 100, reducing the compression power consumption of subsequent impellers 100. By using two compressors 200 and a total of four impellers 100 to boost pressure, a pressure ratio of 4.5 and a temperature rise of over 40°C can be achieved for the natural working fluid.

[0106] Furthermore, each compressor 200 can be controlled independently.

[0107] Since each compressor 200 can be controlled independently, the compressor 200 can be operated at different speeds to achieve efficient and wide-range operation at high pressure ratios.

[0108] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0109] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An impeller for a compressor using water as a working medium, characterized by comprising: The impeller includes a hub and a set of blades disposed on the hub, the set of blades including at least a first set of blades, a second set of blades and a third set of blades; The first blade group includes a plurality of first blades, the second blade group includes a plurality of second blades, and the third blade group includes a plurality of third blades; along the circumference of the hub, a second blade is provided between every two adjacent first blades, and a third blade is provided between each first blade and a second blade; The lengths of the first blade, the second blade, and the third blade decrease sequentially; the lengths L1 and L3 of the first blade satisfy: 50% ≤ L3 / L1 ≤ 60%; and / or the lengths L1 and L2 of the first blade satisfy: 70% ≤ L2 / L1 ≤ 80%; along the radial direction of the impeller, the distances between the leading edges of the first blade, the second blade, and the third blade and the leading edge of the hub gradually decrease; the first blade and the second blade are both backward-curved blades, and the third blade is a radially straight blade; the outlet installation angles of the first blade and the second blade range from 30° to 45°; the outlet installation angle of the third blade is 90°.

2. The impeller of claim 1, wherein The ratio of the thickness at the leaf root to the thickness at the leaf tip of the first leaf, the second leaf, and the third leaf is 2.5 to 3.

3. The impeller of claim 1, wherein The leading edge cross-sectional shape of the first blade, the second blade, and the third blade is semi-elliptical.

4. The impeller according to claim 1, characterized in that, The impeller is made of titanium alloy.

5. A compressor, characterized in that, Includes the impeller as described in any one of claims 1 to 4.

6. The compressor according to claim 5, characterized in that, The compressor also includes a primary impeller, a secondary impeller, a motor stator, and a motor rotor; The motor stator is disposed on the outer side of the motor rotor along the circumference of the motor rotor, and the first-stage impeller and the second-stage impeller are disposed at opposite ends of the motor rotor; wherein, the first-stage impeller and the second-stage impeller are both impellers.

7. A compressor unit, characterized in that, It includes two compressors as described in claim 5 or 6, the two compressors being connected sequentially along the axial direction.

8. A heat pump system, characterized in that, Including the compressor as described in claim 5 or 6; or The heat pump system includes the compressor unit as described in claim 7.

9. The heat pump system according to claim 8, characterized in that, When the heat pump system includes the compressor unit, each compressor can be controlled independently.

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