Centrifugal impeller for cooling an electric machine
By optimizing the centrifugal impeller structure and dust collection port design, the problems of slow airflow and incomplete impurity separation in the motor cooling device were solved, achieving efficient heat dissipation and impurity filtration, and improving the motor's operational stability and lifespan.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- WEIHAI CREDITFAN VENTILATOR
- Filing Date
- 2025-08-04
- Publication Date
- 2026-06-26
AI Technical Summary
In existing motor cooling devices, the unoptimized centrifugal impeller structure results in slow airflow, requiring the use of an additional axial flow fan. Furthermore, impurities in the incoming airflow cannot be effectively separated, affecting motor operation.
By optimizing the centrifugal impeller structure, including the design of the front disc, rear disc, and guide structure, combined with the dust removal port, rapid airflow and effective filtration of impurities are achieved.
It achieves rapid airflow inside the motor and effective filtration of impurities, reducing system energy consumption and avoiding mechanical wear and electrical short circuits caused by impurities.
Smart Images
Figure CN224413950U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of motor temperature control technology, specifically to a centrifugal impeller for cooling motors. Background Technology
[0002] Motors inevitably generate heat during operation, especially high-speed, high-power motors. If the heat generated during operation cannot be dissipated from the motor housing in a timely manner, the internal temperature of the motor will increase significantly, which will have an adverse effect on the motor's operational stability and service life. Therefore, good heat dissipation during motor operation is an important guarantee for the motor to work stably and continuously.
[0003] Currently, there are motor cooling devices that use axial flow fans and other equipment to introduce cooler external airflow into the motor for heat exchange, and then use centrifugal impellers to expel the hot airflow from the motor. However, these existing motor cooling solutions have the following drawbacks: First, because the centrifugal impeller structure is not optimized, it cannot independently achieve rapid airflow inside the motor, requiring an additional axial flow fan to increase the airflow velocity, which undoubtedly increases the system energy consumption for cooling the motor. Second, this "axial flow fan intake, centrifugal impeller exhaust" flow design cannot effectively separate and filter impurities in the intake airflow. In harsh environments, this can lead to excessive sand and dust entering the motor, causing mechanical wear and even electrical short circuits. Utility Model Content
[0004] To address the problems existing in the prior art, this application provides a centrifugal impeller for motor cooling through embodiments. Through optimized design of the impeller structure, the centrifugal impeller can independently achieve rapid airflow inside the motor and effectively filter impurities in the intake airflow without additional auxiliary guiding devices.
[0005] The centrifugal impeller provided in this application is disposed inside the motor housing, including a front disc and a rear disc coaxially disposed with the motor shaft, and a plurality of centrifugal blades fixedly disposed circumferentially between the front disc and the rear disc. An airflow inlet is provided on the side of the motor housing through which the motor shaft passes, and a heat dissipation vent is provided on the side away from the airflow inlet.
[0006] The front disc includes a first annular region fixedly connected to the centrifugal blade, and a first guide structure that bends radially from the outside to the inside toward the airflow inlet, wherein the outer diameter of the first annular region is greater than the maximum radial distance of the airflow inlet, and the inner diameter of the first guide structure is not less than 90% of the maximum radial distance of the airflow inlet;
[0007] The rear disc includes a second annular region fixedly connected to the centrifugal blades, and a connecting portion fixedly connected to the motor shaft, wherein the connecting portion has a concave shape that gradually contracts from front to back along the axial direction.
[0008] The motor housing is also provided with a dust removal port, which is located axially between the airflow inlet and the centrifugal impeller.
[0009] Preferably, the outer diameter of the second annular region is greater than the inner diameter of the first annular region and smaller than the outer diameter of the first annular region.
[0010] Preferably, the rear disc further includes a second flow guide structure, which is disposed at the junction of the second annular region and the connecting portion, has an inwardly protruding annular shape, and bends radially from the outside to the inside toward the airflow inlet.
[0011] Preferably, the inner diameter of the second flow guide structure is larger than the inner diameter of the airflow inlet, but smaller than 1.1 times the inner diameter of the airflow inlet.
[0012] Preferably, the width of the centrifugal airflow channel formed by the front and rear discs first contracts and then remains constant, or first contracts and then expands, in the radial direction from the inside to the outside.
[0013] Preferably, the end face of the first flow guide structure facing the airflow inlet is parallel to the inner wall of the motor housing at the airflow inlet, and the end face of the second flow guide structure facing the airflow inlet is parallel to the inner wall of the motor housing at the airflow inlet.
[0014] Preferably, the minimum distance between the front or rear disc and the inner wall of the motor housing increases with the increase of the rated speed of the motor until a preset distance threshold is reached.
[0015] Optionally, the centrifugal blade is a radial centrifugal blade or a backward centrifugal blade.
[0016] Preferably, the centrifugal blade has an airfoil profile, and the ratio of the thickness to the chord length of each cross-section of the airfoil is 15% to 42%.
[0017] The centrifugal impeller provided in this application embodiment, through the optimization of the impeller front and rear disc structures and the coordination of the dust removal port, can effectively remove impurities in the airflow flowing into the motor and guide the remaining airflow to flow smoothly through the motor interior. While ensuring efficient heat dissipation and cooling of the motor, it avoids the impact of impurities in the airflow on the internal structure and operation of the motor. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the structure of a centrifugal impeller provided according to an embodiment of this application;
[0019] Figure 2 This is a top view of a centrifugal impeller provided according to an embodiment of this application;
[0020] Figure 3 This is a cross-sectional view of a centrifugal impeller provided according to an embodiment of this application;
[0021] Figure 4 This is a cross-sectional view of a centrifugal impeller provided according to an embodiment of this application;
[0022] Figure 5 The present invention provides a schematic diagram of a motor structure with a centrifugal impeller in some embodiments.
[0023] Figure 6 In some embodiments, a top view of a motor with a centrifugal impeller provided in this application is shown.
[0024] Figure 7 An exploded view of a motor with a centrifugal impeller provided in this application in some embodiments;
[0025] Figure 8 This is a cross-sectional view of a motor with a centrifugal impeller provided in this application in some embodiments;
[0026] Figure 9 This is a schematic diagram of airflow in a motor with a centrifugal impeller provided in this application, as shown in some embodiments.
[0027] Figure 10 This is a schematic diagram of airflow in a motor with a centrifugal impeller provided in this application, as shown in some embodiments.
[0028] Figure 11 This is a schematic diagram of the structure of a centrifugal impeller provided according to an embodiment of this application;
[0029] Figure 12 This is a top view of a centrifugal impeller provided according to an embodiment of this application;
[0030] Figure 13 This is a front view of a centrifugal impeller provided according to an embodiment of this application;
[0031] Figure 14 This is a cross-sectional view of a centrifugal impeller provided according to an embodiment of this application.
[0032] Numbers in the diagram
[0033] Centrifugal impeller 1, front plate 11, first annular zone 111, first guide structure 112, end face 1121, rear plate 12, second annular zone 121, connecting part 122, second guide structure 123, end face 1231, centrifugal blade 13, motor hole 14, motor 2, upper cover 211, motor housing 212, lower cover 213, airflow inlet 22, heat dissipation port 23, dust removal port 24, stator core 251, stator winding 252, rotor structure 26, heat exchange channel 261, motor shaft 27, key 271, guide ring 28, circumferential rotation channel 29, upper bearing 31, upper bearing cover 311, lower bearing 32, lower bearing cover 321, external airflow 41, circumferential rotation airflow 42, ejected airflow 43, heat exchange airflow 44, impurities 5. Detailed Implementation
[0034] The present application will now be further described based on preferred embodiments and with reference to the accompanying drawings.
[0035] For ease of understanding, the various components on the drawings have been enlarged or reduced, but this is not intended to limit the scope of protection of this application.
[0036] In the description of the embodiments of this application, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, they 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 have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, in the description of this application, in order to distinguish different units, the terms "first," "second," etc. are used in this specification, but these are not limited by the manufacturing order, nor should they be construed as indicating or implying relative importance. Their names may differ in the detailed description and claims of this application.
[0037] The vocabulary used in this specification is for illustrative purposes and is not intended to limit the scope of this application. It should also be noted that, unless otherwise expressly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection via an intermediate medium; or they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of these terms in this application.
[0038] This application provides a centrifugal impeller 1 for cooling a motor. The centrifugal impeller 1 is disposed inside the motor housing and rotates under the drive of the motor shaft. After the external airflow is introduced into the motor through the airflow inlet, the impurities are first discharged from the dust removal port through the circumferential rotation of the airflow. The remaining airflow exchanges heat with the inside of the motor and flows out of the motor through the heat dissipation port, thereby achieving heat dissipation of the motor.
[0039] Figures 1 to 4 The following are schematic diagrams and top views of the centrifugal impeller 1 provided according to some embodiments of this application. Figure 3 and Figure 4 These are cross-sectional views of the centrifugal impeller 1 from both oblique and frontal perspectives, with the cutting lines being... Figure 2 AA line in the middle; Figures 5 to 8 The diagrams shown below illustrate, in some embodiments, the structure of the motor 2 with the centrifugal impeller 1, including a top view, an exploded view, and a cross-sectional view (the cutting line is shown below). Figure 6 (BB line in the middle).
[0040] refer to Figures 5 to 8 The outermost part of motor 2 is the motor housing, which can optionally be, for example... Figures 5 to 8 As shown, the motor housing can be composed of a detachably connected upper cover 211, a motor housing 212, and a lower cover 213, or it can be constructed in other ways known to those skilled in the art.
[0041] The core components inside the motor 2 are the stator structure, the rotor structure 26, and the motor shaft 27, as shown in the figures above. The stator structure is fixedly connected to the inner wall of the motor housing 212, including the stator core 251 and multiple sets of circumferentially distributed windings 252 wound on the stator core 251. The stator windings can be connected in a DC drive or AC drive manner and connected to the power supply through a connector not shown in the figure.
[0042] The rotor structure 26 is located inside the stator structure and includes several magnets with alternating magnetic poles along the circumferential direction. The motor shaft 27 is coaxially arranged with the rotor structure 3. One end of the shaft extends out of the motor housing and can be connected to the driven components via a key 271. The middle part is fixedly arranged inside the rotor structure 26, and the parts protruding from the rotor structure 26 on both sides are housed in the motor housing via an upper bearing 31 and a lower bearing 32. After applying DC or AC current to the motor, it can rotate relative to the motor housing around its axis and the speed can be adjusted under the control of a control unit or frequency converter (not shown in the figure).
[0043] In addition, the motor housing also includes an upper bearing cover 311 and a lower bearing cover 321 for limiting and pre-tightening the upper bearing 351 and the lower bearing 32. Obviously, the upper bearing cover 311 also has a through hole for the motor shaft 27 to pass through.
[0044] The structures and assembly methods of the above-mentioned parts are all common designs known to those skilled in the art. Any adjustments or replacements made to the above-mentioned structures and components based on the specific usage environment and design specifications without departing from the technical concept of this application shall be covered within the protection scope of this application.
[0045] Furthermore, the motor housing includes at least one airflow inlet 22 and one heat dissipation vent 23. The airflow inlet 22 is located on the upper part of the motor housing, specifically on the side of the motor housing through which the motor shaft 27 passes. For example, it can be like... Figure 5 As shown, multiple airflow inlets 22 are distributed circumferentially on the upper cover 211 and penetrate the upper cover 211 to form a channel for airflow into the motor; heat dissipation vents 23 are located at the lower part of the motor housing, for example, like... Figure 5 As shown, it is located on the side of the motor housing 212 away from the airflow inlet 22, or it can be located on the lower cover 213.
[0046] In order to effectively cool the motor during operation, in some preferred embodiments, such as Figure 5 As shown, a plurality of axially penetrating heat exchange channels 261 are provided on the rotor structure 26. When the number of heat exchange channels is greater than two, they can be arranged circumferentially to introduce relatively low-temperature airflow from the outside of the motor 2 and discharge it from the motor 2 after absorbing heat from inside the motor 2. In addition, in order to better guide the high-temperature gas out of the motor 2, a guide ring 28 is also provided between the rotor structure 26 and the lower cover 213.
[0047] The centrifugal impeller 1 is housed inside the motor housing and fixedly connected to the motor shaft 27. It can drive the airflow under the influence of the motor shaft 27. (See reference...) Figures 1 to 4 The centrifugal impeller 1 includes a front disc 11 and a rear disc 12 coaxially arranged with the motor shaft 27, and a plurality of centrifugal blades 13 fixedly arranged circumferentially between the front disc 11 and the rear disc 12.
[0048] Specifically, the front plate 11 includes a first annular region 111 fixedly connected to the centrifugal blade 13, and a first guide structure 112 that bends radially from the outside to the inside toward the airflow inlet 22; the rear plate 12 includes a second annular region 121 fixedly connected to the centrifugal blade 13 and a connecting portion 122, wherein the connecting portion 122 has a concave shape that gradually shrinks from front to back along the axial direction, and a motor hole 14 through which the motor shaft 27 passes is opened in the middle. The motor shaft 27 can be fixedly connected to the connecting portion 122 by interference fit or key connection.
[0049] Furthermore, a dust removal port 24 is also provided on the motor housing, such as... Figure 5As shown, the dust removal port 24 can be installed on the motor housing 212, and it is located axially between the airflow inlet and the centrifugal impeller 1.
[0050] Figure 9 Oblique half-section view (section line is) Figure 6 (CC line in the middle) and Figure 10 The internal top view shows the airflow of the motor 2 cooling through the centrifugal impeller 1. The following is combined with... Figure 9 , Figure 10 The working principle of centrifugal impeller 1 is introduced below:
[0051] 1) After the motor 2 enters the working state, the rotor structure 26 and the motor shaft 27 rotate relative to the stator structure and generate heat. Driven by the motor shaft 27, the centrifugal impeller 1 rotates, driving the external airflow 41 to enter the interior of the motor 2 from the airflow inlet 22. Then, it is driven by the centrifugal impeller 1 to flow towards the inner wall of the motor housing. Under the constraint of the inner wall, an airflow rotating in the circumferential direction is formed (i.e., the circumferential rotating airflow 42 in the figure). At this time, sand, dust and other impurities 5 in the airflow are gradually thrown to the outer layer of the circumferential rotating airflow 42 under the action of centrifugal force. When the circumferential rotating airflow 42 flows to the dust removal port 24, a part of it will flow out of the motor 2 in a circumferential rotation through the dust removal port 24, that is, forming the ejection airflow 43. At the same time, the impurities 5 in the circumferential rotating airflow 42, after losing the constraint of the inner wall of the motor housing, are thrown out of the motor housing with this part of the ejection airflow 43, thereby realizing the dust removal operation of the airflow flowing into the motor from the outside.
[0052] 2) As the centrifugal impeller 1 continues to rotate, the external airflow 41 continuously enters the motor. In addition to the ejected airflow 43 that flows out of the motor 2 through the dust removal port 24, the remaining part of the circumferential rotating airflow 42 will gradually flow downward along the axial direction. It flows into the rotor structure 26 from the end of the heat exchange channel 261 near the airflow inlet 22 and flows out of the rotor structure 26 from the end of the heat exchange channel 261 away from the airflow inlet 22 (this part of the airflow is the heat exchange airflow 44). As analyzed above, this part of the heat exchange airflow 44 flows out of the motor through the heat dissipation port 23, thereby carrying away the heat generated by the operation of the motor 2 from the motor 2.
[0053] To make the most of the airflow entering the motor 2 and to shorten the radial guidance path of the airflow (this shortening of the guidance path is particularly beneficial for reducing the power consumption of the motor in driving the centrifugal impeller 1, i.e., avoiding excessive energy consumption by the motor 2 for heat dissipation, which would lead to excessive energy loss in driving the load), the width of the front plate 11 can be set to be narrower and its position as outward as possible. Therefore, in the embodiments of this application, such as... Figures 5 to 8As shown, the outer diameter of the front disc 11, i.e. the outer diameter of the first annular region 611, is greater than the maximum radial distance of each airflow inlet 22; the inner diameter of the front disc 11, i.e. the inner diameter of the first guide structure 112, is not less than 90% of the maximum radial distance of each airflow inlet 22. With this setting, the airflow entering the motor through the airflow inlet 22 can form a circumferential rotating airflow more quickly, effectively reducing the power consumption of the motor 2 driving the centrifugal impeller 1.
[0054] As can be seen, the centrifugal impeller provided in this application, through the optimization of the front disc structure and the cooperation of the dust removal port, can effectively remove impurities in the airflow flowing into the motor and guide the remaining airflow to flow smoothly through the heat exchange channel 261. While ensuring efficient heat dissipation and cooling of the motor 2, it avoids the impact of impurities in the airflow on the internal structure and operation of the motor 2.
[0055] To further enhance the dust removal and cooling effect, the internal structure of the centrifugal impeller 1 and the motor 2 can also be further optimized.
[0056] For example, in some preferred embodiments, such as Figures 1 to 4 As shown, the outer diameter of the second annular region 121 can be set to be larger than the inner diameter of the first annular region 111 but smaller than the outer diameter of the first annular region 111. Reducing the outer diameter of the second annular region 121 can expand the flow channel of the heat exchange airflow 44 after dust removal, reduce the airflow velocity, and reduce flow loss.
[0057] In some preferred embodiments, such as Figures 1 to 4 As shown, the first annular region 111 and the second annular region 121 are arranged horizontally or approximately horizontally along the radial direction at the outlet of the blade 13. With this structural arrangement, the centrifugal airflow channel formed by the front disc 11 and the rear disc 12 of the centrifugal impeller 1 gradually contracts from the inside to the outside along the radial direction, and then forms a horizontal radial channel with a constant width or a horizontal radial channel with a relatively slow expansion. This can effectively prevent the external airflow 41 from generating axial velocity after entering the motor housing, causing it to directly become heat exchange airflow 44 without passing through the dust removal and filtration process of the dust removal port 24.
[0058] In some embodiments, an inwardly tapered frustum structure may be provided on the inner wall of the motor housing 212. The frustum structure may be integrally formed with the motor housing 212, or it may be fixedly connected to the inner wall of the motor housing 212 by means of bonding, welding, etc. As shown in the figure, its position is located below the dust removal port 24, and the part where it is joined with the inner wall of the motor housing 212 is rounded or chamfered to form a circumferential rotating channel 29. The circumferential rotating channel 29 can make the circumferential rotating airflow 42 rotate in a relatively stable state at this position.
[0059] In some embodiments, a second flow guiding structure 123 is also provided on the rear disc 12, such as... Figures 1 to 4 As shown, the second flow guiding structure 123 is disposed at the junction of the second annular region 121 and the connecting portion 122, and has an inwardly protruding annular shape, curving radially from the outside to the inside toward the airflow inlet 22; preferably, the inner diameter of the second flow guiding structure 123 is larger than the inner diameter of the airflow inlet 22, but smaller than 1.1 times the inner diameter of the airflow inlet. By providing the second flow guiding structure 123 and limiting its inner diameter to between 1 and 1.1 times the inner diameter of the airflow inlet 22, the external airflow 41 entering the motor housing can be better received at the edge of the airflow inlet 22, allowing it to be better guided radially and minimizing its entry into the bowl-shaped bottom space of the connecting portion 122.
[0060] During the rotation of the centrifugal impeller 1 relative to the motor housing as the motor shaft 27 rotates, its front disc 11 and rear disc 12 must maintain a certain distance from the inner wall of the motor housing to avoid contact with it. Specifically, in Figures 5 to 8 In the illustrated embodiment, the minimum distances between the front disc 11, the rear disc 12, and the inner wall of the motor housing are respectively the distances between the end face 1121 of the first flow guiding structure 112 and the end face 1231 of the second flow guiding structure 123 and the lower surface of the upper cover 211. Preferably, the end face 1121 of the first flow guiding structure 112 facing the airflow inlet 22 is parallel to the inner wall of the motor housing (more specifically, the upper cover 211 in the figure) at the airflow inlet 22, and the end face 1231 of the second flow guiding structure 123 facing the airflow inlet 22 is also parallel to the inner wall of the motor housing at the airflow inlet 22.
[0061] During the rotation of the motor, a "gas barrier" formed by the flowing airflow can be formed between the end face 1121, the end face 1231 and the lower surface of the upper cover 211 to block the passage of impurities 5. The blocking effect of the "gas barrier" increases with the increase of the motor speed. Therefore, in some preferred embodiments, the minimum distance can be increased with the increase of the rated speed of the motor, thereby further reducing the amount of material used in the front disc 11 and the rear disc 12 and reducing the weight of the centrifugal impeller 1.
[0062] At the same time, it should be noted that the minimum distance mentioned above cannot be increased indefinitely. This is because when the distance between end face 1121 or end face 1231 and the lower surface of the upper cover 211 exceeds a certain limit, the "gas barrier" effect will be drastically reduced. Therefore, preferably, a preset distance threshold can be set. After the minimum distance between the front disc 11 or rear disc 12 and the inner wall of the motor housing increases to the preset distance threshold as the rated speed of the motor increases, it will no longer continue to increase.
[0063] In the embodiments of this application, such as Figures 1 to 4As shown, centrifugal blades 13 are circumferentially spaced between the front plate 11 and the rear plate 12. The centrifugal blades 13 have airfoil-shaped profiles, and their orientation can be adjusted according to the rotation direction of the motor 2. For example, Figures 1 to 4 The centrifugal impeller 1 shown is suitable for a motor 2 that can rotate in both directions. In order to ensure the same airflow guiding effect when rotating in both directions, the blade 13 adopts a radial centrifugal blade, that is, its leading edge to trailing edge does not bend forward or backward in a certain direction of rotation. At this time, the center line of the profile of each cross section of the centrifugal blade 13 is a straight line and passes through the axis of the motor shaft 27.
[0064] When the motor is a unidirectional rotating motor, it can also be like... Figures 11 to 14 As shown, a backward centrifugal blade is adopted to further enhance the aerodynamic effect of the centrifugal impeller 1 when the motor rotates in one direction.
[0065] In some preferred embodiments, in order to maximize the effective work of the blades within the same space and size, blades with different airfoils at different cross sections can be used: for example, the airfoil chord length of the blade 13 cross section can be gradually increased from the front disk 11 to the rear disk 12; or, the outer diameter of the blade at the front disk 11 can be greater than the outer diameter of the blade at the rear disk 12, and the inner diameter of the blade at the front disk 11 can be greater than the inner diameter of the blade at the rear disk 12, thereby causing the blade at the rear disk 12 to tilt radially inward.
[0066] In some preferred embodiments, the centrifugal blades 13 may employ a shorter, thicker, non-standard airfoil, for example, like... Figure 14 As shown, the ratio of the thickness t to the chord length c of each section of the centrifugal blade 13 can be set between 15% and 42%. By increasing the maximum thickness of the airfoil, both aerodynamic and strength requirements can be met while reducing noise.
[0067] The specific embodiments of this application have been described in detail above. For those skilled in the art, several improvements and modifications can be made to this application without departing from the principle of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.
Claims
1. A centrifugal impeller for cooling a motor, disposed inside a motor housing, comprising a front disc and a rear disc coaxially arranged with the motor shaft, and a plurality of centrifugal blades fixedly arranged circumferentially between the front and rear discs, wherein an airflow inlet is provided on the side of the motor housing through which the motor shaft passes, and a heat dissipation vent is provided on the side away from the airflow inlet, characterized in that, The front disc includes a first annular region fixedly connected to the centrifugal blade, and a first guide structure that bends radially from the outside to the inside toward the airflow inlet, wherein the outer diameter of the first annular region is greater than the maximum radial distance of the airflow inlet, and the inner diameter of the first guide structure is not less than 90% of the maximum radial distance of the airflow inlet; The rear disc includes a second annular region fixedly connected to the centrifugal blades, and a connecting portion fixedly connected to the motor shaft, wherein the connecting portion has a concave shape that gradually tapers from front to back along the axial direction. The motor housing is also provided with a dust removal port, which is located axially between the airflow inlet and the centrifugal impeller.
2. The centrifugal impeller for cooling a motor according to claim 1, characterized in that, The outer diameter of the second annular region is greater than the inner diameter of the first annular region, but smaller than the outer diameter of the first annular region.
3. The centrifugal impeller for cooling a motor according to claim 1, characterized in that, The rear disc also includes a second flow guide structure, which is disposed at the junction of the second annular region and the connecting portion, has an inwardly protruding annular shape, and bends radially from the outside to the inside toward the airflow inlet.
4. The centrifugal impeller for cooling a motor according to claim 3, characterized in that, The inner diameter of the second flow guide structure is larger than the inner diameter of the airflow inlet, but smaller than 1.1 times the inner diameter of the airflow inlet.
5. The centrifugal impeller for cooling a motor according to any one of claims 1 to 4, characterized in that, The width of the centrifugal airflow channel formed by the front and rear discs either contracts radially from the inside out and then remains constant, or contracts and then expands.
6. The centrifugal impeller for cooling a motor according to claim 3 or 4, characterized in that, The end face of the first flow guiding structure facing the airflow inlet is parallel to the inner wall of the motor housing at the airflow inlet, and the end face of the second flow guiding structure facing the airflow inlet is parallel to the inner wall of the motor housing at the airflow inlet.
7. The centrifugal impeller for cooling a motor according to claim 6, characterized in that, The minimum distance between the front or rear disc and the inner wall of the motor housing increases with the increase of the motor's rated speed until a preset distance threshold is reached.
8. The centrifugal impeller for cooling a motor according to claim 1, characterized in that, The centrifugal blades are radial centrifugal blades or backward centrifugal blades.
9. The centrifugal impeller for cooling a motor according to claim 7, characterized in that, The centrifugal blade has an airfoil profile, and the ratio of the thickness to the chord length of each section of the airfoil is 15% to 42%.