Impeller, impeller assembly and centrifugal compressor adopting impeller

Abstract

The invention discloses an impeller, an impeller assembly comprising the impeller and a centrifugal compressor adopting the impeller, the impeller comprises an impeller cover and an impeller disc, a plurality of groups of first blade grids are arranged on the impeller cover in an array mode, and each group of first blade grids comprises a plurality of first blades which are arranged in a circumferential mode; a plurality of sets of second blade grids are arranged on the wheel disc in an array mode, each set of second blade grids comprises a plurality of second blades which are arranged in a circumferential mode, and the first blade grids and the second blade grids are arranged alternately. According to the impeller, the multiple sets of first blade grids are arranged on the impeller cover in an array mode, and the multiple sets of second blade grids are arranged on the impeller disc in an array mode, so that the power capability of the impeller on gas is remarkably improved; and the production cost and the occupied space are not increased.

Description

Technical Field

[0001] The present invention relates to the technical field of centrifugal compressors, and more particularly to an impeller, an impeller assembly including the impeller, and a centrifugal compressor using the impeller. Background Art

[0002] A centrifugal compressor, also called a "vortex compressor", uses a high-speed rotating impeller to do work on a gas to increase the pressure and kinetic energy of the gas. Subsequently, this part of the kinetic energy is converted into static pressure energy in the diffuser channel, further increasing the gas pressure, thereby achieving the purpose of compressing the gas. Centrifugal compressors are widely used in various technological processes to transport air, various process gases, or mixed gases.

[0003] The centrifugal compressor impeller, also known as the working wheel, is the only component in the centrifugal compressor that does work on the air flow and is the most important component on the rotor. It is generally composed of parts such as a wheel disc, a wheel cover, and blades. Under the action of the impeller blades, the gas rotates at a high speed with the impeller. The gas is affected by the rotating centrifugal force and the diffuser flow in the impeller, and the pressure is greatly increased.

[0004] According to the number of impellers in the compressor, it is divided into single-stage and multi-stage types. If there is only one impeller, it is called a single-stage centrifugal compressor. If several impellers are connected in series, it is called a multi-stage centrifugal compressor. Compared with a single-stage centrifugal compressor, the gas pressure of a multi-stage centrifugal compressor is relatively higher.

[0005] Traditional multi-stage centrifugal compressors include double-cantilever centrifugal compressors. One end of the impeller is supported by a bearing, and the other end is suspended, hence the name. Its structure diagram is as Figure 1 shown. After the gas enters from the first air inlet, it rotates at a high speed with the first impeller and is discharged from the first air outlet. It then enters the second air inlet through the inter-stage pipeline and rotates at a high speed with the second impeller again, and is discharged from the second air outlet. For this double-cantilever centrifugal compressor, since the first critical speed and the second critical speed values of the rotor are relatively close, when starting the compressor to the operating speed, passing through two critical speeds continuously, the vibration value of the compressor is very easy to exceed the allowable value, resulting in large vibration of the compressor and shutdown, and even causing damage to the compressor. Moreover, this compressor is equipped with an inter-stage pipeline, increasing the energy consumption of the compressor; this compressor also adds an impeller, resulting in a significant increase in cost and floor area.

[0006] Application No. 2013201623299 discloses an external cooling isothermal air separation compressor, on which a secondary three - dimensional closed impeller, a quaternary three - dimensional closed impeller, and a tertiary three - dimensional closed impeller are successively arranged along the axial direction of the main shaft. Through the successive compression of the secondary three - dimensional closed impeller, the quaternary three - dimensional closed impeller, and the tertiary three - dimensional closed impeller, the gas pressure entering the compressor is greatly increased. However, this compressor uses a closed impeller, whose strength is inferior to that of a semi - open impeller, and the allowable impeller rim line speed is smaller than that of a semi - open impeller. Under the same pressure ratio, due to the limitation of the maximum rim line speed, the rotational speed of this type of compressor will be lower, the impeller diameter will be larger, the number of impellers will be more, the structure will become more complex, and the usage cost will increase accordingly.

[0007] For the centrifugal compressors disclosed in the prior art, on the premise of meeting the work requirement, most of their structures are relatively complex and the production cost is high, which limits their scope of use. Summary of the Invention

[0008] In view of the above - mentioned defects of the prior art, the present invention provides an impeller. On the hub cover, a plurality of sets of first cascades are arrayed, and on the hub disk, a plurality of sets of second cascades are arrayed, and the first cascades and the second cascades are arranged alternately, so that the fluid entering the impeller is successively compressed by the first cascades and the second cascades for multiple times, improving the pressure and kinetic energy of the fluid, and meeting the work requirements in the current production stage; moreover, since the first cascades and the second cascades are respectively arranged on the hub cover and the hub disk, there is no need to additionally increase components such as impellers, diffusers, bends, return channels, and volutes, which will not have an obvious impact on the impeller structure, production cost, and occupied space. For this reason, the present invention also provides an impeller assembly and a centrifugal compressor using the impeller or the impeller assembly.

[0009] To solve the above - mentioned technical problems, in the first aspect of the present invention, an impeller is provided, which includes a hub cover and a hub disk. A plurality of sets of first cascades are arrayed on the hub cover, and each set of first cascades includes a plurality of first blades arranged in a circumferential pattern.

[0010] A plurality of sets of second cascades are arrayed on the hub disk, and each set of second cascades includes a plurality of second blades arranged in a circumferential pattern, and the first cascades and the second cascades are arranged alternately.

[0011] As a preferred embodiment, two sets of first cascades are arrayed on the hub cover, namely a first inner - layer cascade and a first outer - layer cascade, and two sets of second cascades are arrayed on the hub disk, namely a second inner - layer cascade and a second outer - layer cascade. The first inner - layer cascade, the second inner - layer cascade, the first outer - layer cascade, and the second outer - layer cascade are successively arranged from the inside to the outside along the radial direction.

[0012] As a preferred embodiment, the circumferential inclination direction of the first blades on the hub cover is opposite to the circumferential inclination direction of the second blades on the hub disk.

[0013] In a second aspect of the present invention, there is provided an impeller assembly, including the above-mentioned impeller, wherein the wheel cover is connected to a transmission component through a first cascade.

[0014] The impeller assembly further includes a first motor, an output shaft of the first motor is fixedly connected to a drive shaft, and the drive shaft is fixedly connected to the transmission component.

[0015] A hollow shaft is sleeved on the drive shaft, one end of the hollow shaft is fixedly connected to the wheel disc, and the other end of the hollow shaft is connected to a transmission unit and rotates under the action of the transmission unit.

[0016] A bearing is installed between the drive shaft and the hollow shaft.

[0017] As a preferred embodiment, the transmission unit is a second motor, and an output shaft of the second motor is fixedly connected to the hollow shaft.

[0018] The first motor drives the transmission component to rotate through the drive shaft, and then drives the wheel cover and the first cascade on the wheel cover to rotate; the second motor drives the wheel disc to rotate through the hollow shaft, and then drives the second cascade on the wheel disc to rotate. The wheel disc and the wheel cover are controlled by different motors, and the rotation directions do not interfere with each other, and the rotation effects in the same or opposite directions can be achieved.

[0019] As a preferred embodiment, the bearing is a sliding bearing or a rolling bearing.

[0020] By installing a sliding bearing or a rolling bearing between the drive shaft and the hollow shaft, the drive shaft and the hollow shaft can rotate in opposite directions relative to each other.

[0021] As a preferred embodiment, the transmission unit includes a driving bevel gear, a driven bevel gear, and a transmission bevel gear. The driving bevel gear is fixedly connected to the drive shaft, the driven bevel gear is fixedly connected to the hollow shaft, and the transmission bevel gear is located between the driving bevel gear and the driven bevel gear and meshes with the driving bevel gear and the driven bevel gear respectively.

[0022] The first motor drives the drive shaft to rotate, and the driving bevel gear fixedly connected to the drive shaft rotates accordingly. Since the transmission bevel gear meshes with the driving bevel gear and the driven bevel gear respectively, the driven bevel gear rotates under the action of the transmission bevel gear, and the driven bevel gear drives the hollow shaft and the wheel disc fixedly connected to the hollow shaft to rotate. Through the interaction of the transmission unit with the drive shaft and the hollow shaft, the synchronous movement of the wheel cover and the wheel disc is achieved.

[0023] The transmission bevel gear also has the function of changing the movement direction, so that the driving bevel gear and the driven bevel gear rotate in opposite directions relative to each other, and the wheel cover and the wheel disc can achieve synchronous movement in opposite directions.

[0024] As a preferred embodiment, the bearing is a support bearing.

[0025] As a preferred embodiment, there is a negative incidence angle when the fluid enters the adjacent next set of cascades.

[0026] The existence of the negative incidence angle significantly improves the work capacity of the cascade.

[0027] As a preferred embodiment, the negative incidence angle is 0° to -20°.

[0028] As a preferred embodiment, a fluid inlet is provided at the innermost cascade, and a fluid outlet is provided at the outermost cascade.

[0029] The fluid enters from the innermost cascade, rotates under the action of the cascade, and its kinetic energy and pressure increase accordingly; then the fluid enters the adjacent next set of cascades, and the next set of cascades further does work on the fluid. This process is repeated. After the outermost cascade does work on the fluid, the fluid is discharged from the outlet. The pressure of the fluid after multi-stage compression is greatly increased. At the same time, the flow velocity is also increased during this process, so that the fluid flow rate increases within the same time.

[0030] The fluid here can be a gas or a liquid. When the impeller is applied to a centrifugal compressor, the fluid is a gas; when the impeller is applied to a water pump, the fluid here is water or other liquid; when the impeller is applied to a centrifugal fan, the fluid here is the incoming air.

[0031] In the third aspect of the present invention, a centrifugal compressor is provided, including the above-mentioned impeller or impeller assembly.

[0032] In the fourth aspect of the present invention, a water pump is provided, including the above-mentioned impeller or impeller assembly.

[0033] In the fifth aspect of the present invention, a centrifugal fan is provided, including the above-mentioned impeller or impeller assembly.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) For the impeller of the present invention, by arranging a plurality of sets of first cascades in an array on the shroud and a plurality of sets of second cascades in an array on the hub, the multi-stage compression of the fluid is realized, and the work capacity of the impeller on the fluid is significantly improved; at the same time, it will not cause an increase in production cost and occupied space.

[0036] (2) By using the impeller of the present invention, a stable continuous flow of gas is established inside the impeller, and it can be applied to occasions with large viscous force and small gas density.

[0037] (3) By using the impeller of the present invention, the number of stages of the first cascade and the second cascade can be flexibly selected according to the needs of the use scenario, expanding the scope of use.

[0038] The concept, specific structure, and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, features, and effects of the present invention. Description of the Drawings

[0039] Figure 1 is a schematic structural diagram of an existing double-cantilever centrifugal compressor;

[0040] Figure 2 is a schematic structural diagram of the impeller in Embodiment 1 of the present invention;

[0041] Figure 3 is Figure 2 a schematic structural diagram of removing the shroud in

[0042] Figure 4 is a schematic diagram of the movement relationship of each group of cascades in Embodiment 1 of the present invention;

[0043] Figure 5 is a schematic structural diagram of the impeller assembly in Embodiment 2 of the present invention;

[0044] Figure 6 is a schematic structural diagram of the impeller assembly in Embodiment 3 of the present invention;

[0045] Figure 7 is a power curve graph of the compressor at different angles of attack;

[0046] Figure 8 is a pressure ratio curve graph of the compressor at different angles of attack;

[0047] Figure 9 is an efficiency curve graph of the compressor at different angles of attack.

[0048] Wherein: 1 - shroud, 2 - disk, 3 - rolling bearing, 4 - second motor, 5 - hollow shaft, 6 - first motor, 7 - drive shaft, 8 - first inner cascade, 9 - first outer cascade, 10 - second inner cascade, 11 - second outer cascade, 12 - transmission component, 13 - driving bevel gear, 14 - driven bevel gear, 15 - transmission bevel gear. Detailed Embodiments

[0049] In order to make the technical means, creative features, achieved purposes, and effects of the invention easy to understand, the present invention will be further described below in conjunction with specific illustrations. However, the present invention is not limited to the following implemented cases.

[0050] It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the conditions under which the present invention can be implemented. Therefore, they do not have substantial technical significance. Any modification of the structure, change in the ratio relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope that can be covered by the technical content disclosed in the present invention.

[0051] Embodiment 1

[0052] For example Figure 2 , an impeller includes a shroud 1 and a hub 2. A plurality of groups of first cascades are arranged in an array on the shroud 1. Each group of first cascades includes a plurality of first blades arranged in a circumferential manner; a plurality of groups of second cascades are arranged in an array on the hub 2. Each group of second cascades includes a plurality of second blades arranged in a circumferential manner, and the first cascades and the second cascades are arranged alternately.

[0053] The shroud 1 and the hub 2 are respectively provided with blades in an array. The shroud 1 and the hub 2 do not enclose a closed space but present a semi-open structure, and the outermost peripheral linear velocity of the impeller can reach 500 m / s.

[0054] There are a plurality of groups of first cascades. Each group of first cascades includes a plurality of first blades. The number of first blades can be odd or even, and the staff can determine it according to factors such as the noise level of the impeller and the stability of the impeller. The first blades are arc-shaped, and the blades used in the impeller in the prior art can all be used in this application.

[0055] Each group of first cascades is formed by arranging a plurality of first blades in a circumferential direction. Multiple groups of first cascades are arranged in sequence from the inside to the outside along the radial direction of the shroud 1, and the diameters of the circumferences where they are located increase step by step.

[0056] The setting of the second cascades and the second blades is similar to that of the first cascades and the first blades. The difference is that the circumferential inclination direction of the first blades along the shroud 1 is opposite to the circumferential inclination direction of the second blades along the hub 2. For the first blade located in the innermost side, the adjacent second blade is on its outer side, and then the next group of first blades is adjacent to the second blade. In this way, the first cascades composed of the first blades and the second cascades composed of the second blades are arranged alternately in sequence, and the fluid entering the impeller enters the first cascades and the second cascades in sequence for step-by-step compression.

[0057] For occasions with relatively low requirements for the pressure ratio, the first cascades and the second cascades can be respectively set to two groups, such as Figure 3 , 4, along the radial direction of the shroud 1, the first cascade is respectively the first inner cascade 8 and the first outer cascade 10, and along the radial direction of the disk 2, the second cascade is respectively the second inner cascade 9 and the second outer cascade 11. The first inner cascade 8, the second inner cascade 9, the first outer cascade 10, and the second outer cascade 11 are arranged in sequence from inside to outside.

[0058] In actual use, the first and second cascades are not limited to two groups. To further increase the work capacity of the impeller, cascades can be added to the outer edge of the cascades originally arranged on the shroud 1 or the disk 2, which avoids the increase in production costs and floor area caused by adding impellers and associated components (such as diffusers, volutes, and inter-stage connection components, etc.).

[0059] The fluid entering the impeller passes through the successive work of the first inner cascade 8, the second inner cascade 9, the first outer cascade 10, and the second outer cascade 11 respectively, and the pressure of the fluid is significantly increased. The fluid here can be liquid, air, various process gases, or mixed gases.

[0060] The first inner cascade 8, the second inner cascade 9, the first outer cascade 10, and the second outer cascade 11 are arranged alternately. In use, the first inner cascade 8 and the first outer cascade 10 rotate in the same direction, and the second inner cascade 9 and the second outer cascade 11 rotate in the same direction, but rotate in the opposite direction to the first inner cascade 8 and the first outer cascade 10. Moreover, for the convenience of fluid entry, the circumferential inclination direction of the first blade is opposite to the rotation direction of the shroud 1, and the circumferential inclination direction of the second blade is opposite to the rotation direction of the disk 2.

[0061] The way of arranging an array of cascades on the shroud 1 and the disk 2 of the impeller in this application significantly improves the work capacity for the fluid and saves production costs without increasing the number of impellers and other associated components.

[0062] The impeller of the present invention can be applied to occasions with large viscous force and small gas density. For gases with large viscous force and small density, it is difficult for the gas to separate from the solid wall surface, making it difficult to establish a continuous flow state inside the impeller. After the gas is repeatedly agitated inside the impeller, it still cannot be discharged from the impeller outlet. By using the impeller of the present invention, the gas is compressed by multiple groups of cascades, the flow rate is significantly increased, a stable continuous flow can be established inside the impeller, and the gas with large viscous force and small density can also be quickly discharged from the impeller outlet after the action of the impeller.

[0063] Embodiment 2

[0064] As Figure 5, An impeller assembly includes the above-mentioned impeller. The wheel cover 1 is connected to the transmission component 12 through the first cascade. Here, the transmission component 12 can be selected as the hub. Of course, in actual use, it is not limited to the hub, and any component that can transfer energy to make the wheel cover 1 rotate accordingly can be used in this application.

[0065] The impeller assembly further includes a first motor 6. The output shaft of the first motor 6 is fixedly connected to a drive shaft 7. The drive shaft 7 is fixedly connected to the transmission component 12. A hollow shaft 5 is sleeved on the drive shaft 7. One end of the hollow shaft 5 is fixedly connected to the wheel disc 2, and the other end of the hollow shaft 5 is connected to the output shaft of the second motor 4. A sliding bearing or a rolling bearing 3 is installed between the drive shaft 7 and the hollow shaft 5.

[0066] The setting of the sliding bearing or the rolling bearing 3 realizes the independent movement of the drive shaft 7 and the hollow shaft 5 without interference from each other. In this application, the rolling bearing 3 is preferably used, which is convenient to use. However, in this application, a sliding bearing can also be used to replace the rolling bearing 3. When in use, by setting the pipes for injecting and discharging lubricating fluid, forced lubrication of the sliding bearing can be carried out, and the function of the rolling bearing 3 can also be realized. The pipes for injecting and discharging lubricating fluid are conventional technical means in the art, and those skilled in the art can make flexible selections according to the actual situation.

[0067] The first motor 6 drives the transmission component 12 to rotate through the drive shaft 7, and then drives the wheel cover 1 and the first cascade on the wheel cover 1 to rotate. The second motor 4 drives the wheel disc 2 and the second cascade on the wheel disc 2 to rotate through the hollow shaft 5. Due to the installation of a sliding bearing or a rolling bearing 3 between the drive shaft 7 and the hollow shaft 5, the first cascade and the second cascade can rotate independently without interference, and then do work on the fluid entering the impeller.

[0068] In order to improve the work capacity of the impeller, there is a negative incidence angle when the fluid enters the next-stage cascade. The incidence angle i, that is, when the air flow enters the blade passage, the included angle formed by the inconsistency between the direction angle β of the relative velocity of the air flow and the blade installation angle β a at that place is defined as i = β a - β. When i > 0, it is a positive incidence angle, and when i < 0, it is a negative incidence angle.

[0069] Taking the example where both the first cascade and the second cascade are two-stage, when the fluid flows out from the first inner-layer cascade 8 and enters the second inner-layer cascade 9, a negative incidence angle -i is generated at the entrance of the second inner-layer cascade 9, and the generated vorticity momentum is U3C 3u , and at this time, the work done by the second inner-layer cascade 9 on the unit fluid is U4C 4u + U3C 3u ; compared with the case without the negative incidence angle -i, the work done by the second inner-layer cascade 9 on the unit fluid increases by U3C 3u。The existence of the negative blade angle -i can achieve the effect of multiple impellers in series. In practical applications, to balance the work done and the actual losses, the negative blade angle -i is controlled within 0° to -5°. The inventor of the present application uses the impeller in the present application in a centrifugal compressor, and through CFD simulation, the performance of the centrifugal compressor at different blade angles is simulated. The compressor power curve at different blade angles is as shown in Figure 7 shown, the compressor pressure ratio curve at different blade angles is as shown in Figure 8 shown, and the compressor efficiency curve at different blade angles is as shown in Figure 9 shown. The flow rate, power, and efficiency of the centrifugal compressor at different blade angles are shown in Table 1.

[0070] Table 1

[0071] Flow rate (kg / s) Power (MW) Efficiency (%) -20° 41.867 4.0618 83.86 0° 39.876 3.7353 85.79 20° 38.225 3.4748 87.2 40° 34.068 3.0605 86.44 60° 26.656 2.33 84.45

[0072] From Figure 7 、 8 、9 and Table 1, it can be seen that when the blade angle is -20°, compared with the blade angles of 0°, 20°, 40°, and 60°, the pressure ratio of the centrifugal compressor increases, the work capacity increases, and the efficiency decreases slightly.

[0073] Therefore, the impeller of the present application can set the blade angle to 0° to -20°, which can not only meet the requirements of work capacity and pressure ratio, but also avoid excessive losses.

[0074] When specifically selecting, when a relatively high pressure ratio is required, a negative blade angle with a larger absolute value needs to be adopted. For example, for a given impeller, when the rotational static stress caused by its rotational speed has reached the allowable value of the material, but the pressure ratio has not yet reached the requirement, a negative blade angle with a larger absolute value can be adopted to increase the pressure. In addition, for a given impeller, when the design rotational speed and pressure ratio can meet the requirements, but the rotational static stress caused by the rotational speed has not yet reached the allowable value of the material, the absolute value of the negative blade angle can be considered to be reduced to improve the efficiency.

[0075] Example 3

[0076] Different from Example 2, the transmission unit is different. Here, the transmission unit includes a driving bevel gear 13, a driven bevel gear 14, and a transmission bevel gear 15, rather than a second motor.

[0077] As shown in Figure 6, An impeller assembly, including the above-mentioned impeller, the wheel cover 1 is connected to the transmission component 12 through the first cascade; the impeller assembly further includes a first motor 6, the output shaft of the first motor 6 is fixedly connected to a drive shaft 7, and the drive shaft 7 is fixedly connected to the transmission component 12; a hollow shaft 5 is sleeved on the drive shaft 7, one end of the hollow shaft 5 is fixedly connected to the wheel disc 2, and the other end of the hollow shaft 5 is connected to a transmission unit; the transmission unit includes a driving bevel gear 13, a driven bevel gear 14 and a transmission bevel gear 15, the driving bevel gear 13 is fixedly connected to the drive shaft 7, the driven bevel gear 14 is fixedly connected to the hollow shaft 5, the transmission bevel gear 15 is axially fixed on the outer bracket, and the transmission bevel gear 15 is located between the driving bevel gear 13 and the driven bevel gear 14 and meshes with the driving bevel gear 13 and the driven bevel gear 14 respectively.

[0078] The first motor 6 drives the wheel cover 1 and the first cascade on the wheel cover 1 to rotate. Since the output shaft of the first motor 6 is fixedly connected to the drive shaft 7, it further drives the driving bevel gear 13 located on the drive shaft 7 to rotate. The transmission bevel gear 15 meshes with the driving bevel gear 13, driving the transmission bevel gear 15 and the driven bevel gear 14 meshing with the transmission bevel gear 15 to rotate. The driven bevel gear 14 drives the hollow shaft 5 and the wheel disc 2 fixedly connected to the hollow shaft 5 to rotate, and the second cascade rotates accordingly. Since the transmission bevel gear 15 meshes with the driving bevel gear 13 and the driven bevel gear 14 respectively, the transmission bevel gear 15 has the function of changing the direction and transmitting the motion, making the rotation directions of the driving bevel gear 13 and the driven bevel gear 14 opposite, and the first cascade and the second cascade rotate in opposite directions accordingly.

[0079] Embodiment 4

[0080] A centrifugal compressor, including the above-mentioned impeller or impeller assembly.

[0081] The centrifugal compressor includes a stator and a rotor. The stator is composed of a diffuser, a bend, a return passage, a volute and a casing; the main component in the rotor is an impeller. Applying the impeller or impeller assembly of the present application to the centrifugal compressor, the high-speed rotating first cascade and second cascade alternately do work on the gas to increase the pressure and kinetic energy of the gas, and then the kinetic energy is converted into pressure energy in the diffuser, further increasing the gas pressure, so as to achieve the purpose of compressing the gas.

[0082] The work ability of the centrifugal compressor of the present invention to the gas is significantly improved, and it can be applied to occasions with higher requirements for pressure ratio.

[0083] Embodiment 5

[0084] A water pump, including the above-mentioned impeller or impeller assembly.

[0085] When starting the water pump, the impeller rotates at a high speed. Liquid or gas is sucked into the inlet of the water pump and enters the impeller. The blades on the impeller will generate centrifugal force as they rotate, pushing the liquid or gas towards the outlet of the water pump. When the liquid or gas is pushed out of the impeller, a decompression area is generated, causing the liquid or gas at the inlet to be affected by the pressure difference and further sucked into the impeller. In this way, a continuous pumping process is formed.

[0086] By using the impeller or impeller assembly of the present application, the work done by the impeller on the liquid or gas increases, the flow rate of the liquid or gas increases, and the water pumping volume greatly increases within the same time.

[0087] Embodiment 6

[0088] A centrifugal fan includes the above-mentioned impeller or impeller assembly.

[0089] The centrifugal fan includes a volute having an air inlet and an air outlet, and the impeller is installed in the volute. The impeller or impeller assembly in the present application is used in the centrifugal fan. During operation, the air flow first enters the first blade row through the volute. The air flow after doing work through the first blade row has a higher speed and flows through the adjacent second blade row. After further doing work through the second blade row, the energy of the air flow is increased again, so that the air flow pressure is doubled and the fan flow rate is also greatly increased. Finally, the air flow enters the volute and flows out of the fan through the volute outlet.

[0090] By using the impeller of the present application, the ventilation requirement can be achieved at a low rotational speed of the impeller, the total pressure efficiency is greatly improved, and the noise and energy consumption are reduced.

[0091] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. An impeller, comprising a shroud and a hub, characterized in that, a plurality of first cascades are arranged in an array on the shroud, and each group of first cascades includes a plurality of first blades arranged in a circumferential manner; a plurality of second cascades are arranged in an array on the hub, and each group of second cascades includes a plurality of second blades arranged in a circumferential manner, and the first cascades and the second cascades are arranged alternately.

2. The impeller according to claim 1, characterized in that, Two groups of first cascades are arranged in an array on the shroud, namely a first inner cascade and a first outer cascade, and two groups of second cascades are arranged in an array on the hub, namely a second inner cascade and a second outer cascade, and the first inner cascade, the second inner cascade, the first outer cascade, and the second outer cascade are arranged in sequence from inside to outside along the radial direction.

3. The impeller according to claim 1, wherein The circumferential inclination direction of the first blade along the shroud is opposite to the circumferential inclination direction of the second blade along the hub.

4. An impeller assembly, characterized in that, An impeller according to any one of claims 1-3, wherein the shroud is connected to a transmission component through the first cascade; The impeller assembly further includes a first motor, an output shaft of the first motor is fixedly connected to a drive shaft, and the drive shaft is fixedly connected to the transmission component; A hollow shaft is sleeved on the drive shaft, one end of the hollow shaft is fixedly connected to the hub, and the other end of the hollow shaft is connected to a transmission unit and rotates under the action of the transmission unit; A bearing is installed between the drive shaft and the hollow shaft.

5. The impeller assembly according to claim 4, characterized in that, The transmission unit is a second motor, and an output shaft of the second motor is fixedly connected to the hollow shaft.

6. The impeller assembly according to claim 5, wherein, The bearing is a sliding bearing or a rolling bearing.

7. The impeller assembly according to claim 4, wherein The transmission unit includes a driving bevel gear, a driven bevel gear, and a transmission bevel gear. The driving bevel gear is fixedly connected to the drive shaft, the driven bevel gear is fixedly connected to the hollow shaft, and the transmission bevel gear is located between the driving bevel gear and the driven bevel gear and meshes with the driving bevel gear and the driven bevel gear respectively.

8. The impeller assembly according to claim 7, characterized in that, The bearing is a support bearing.

9. The impeller assembly according to claim 4, wherein, There is a negative incidence angle when the fluid enters the adjacent next group of cascades.

10. The impeller assembly according to claim 9, characterized in that, The negative incidence angle is 0° to -20°.

11. A centrifugal compressor, characterized in that, An impeller according to any one of claims 1-3 or an impeller assembly according to any one of claims 4-10.

12. A water pump, characterized in that, An impeller according to any one of claims 1-3 or an impeller assembly according to any one of claims 4-10.

13. A centrifugal fan, characterized in that, An impeller according to any one of claims 1-3 or an impeller assembly according to any one of claims 4-10.

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