Stator core

Abstract

The present invention provides a stator core. The stator core comprises a first core unit, a second lamination and a third lamination. The two axial ends of the first core unit are respectively provided with at least one second lamination. The end of the second lamination facing away from the first core unit is provided with at least one third lamination. A plurality of first channels are formed in the first core unit. The second lamination is formed with a plurality of slots, each slot is connected with more than one first channel. The third lamination is formed with a plurality of outlet holes that penetrate in the axial direction, each outlet hole is connected with a slot, wherein a pair of slots and outlet holes that are connected to each other satisfy that: the outlet hole is located in the radial innermost area of ​​the slot, and when the stator core is placed horizontally, for the slot extending to the lower semicircular part of the core, the connected outlet holes are located at the highest position of the slot. The stator core according to the present invention can spray coolant to the coil at the end of the core without using an oil spray ring, and the coil is uniformly cooled at all locations in the circumferential direction.

Description

Technical Field

[0001] The present invention relates to the field of motors, and more particularly to a stator core for a motor. Background Art

[0002] The stator of a motor running at high power will generate a lot of heat, and it is usually necessary to cool the stator core of the motor and the windings exposed at both ends of the core (also known as end coils in the industry).

[0003] A commonly used method in the prior art is to set a coolant channel inside the iron core and set an oil spray ring at both ends of the iron core. The oil spray ring is formed with an oil spray hole, which is connected to the coolant channel inside the iron core, so that the coolant flowing through the iron core can be sprayed out from the oil spray hole and sprayed to the end coil.

[0004] However, the setting of the oil injection ring will occupy space inside the motor, limiting the improvement of the motor's power density; and the setting of the oil injection ring will increase the complexity of the motor's internal components, increasing the difficulty of motor assembly. Summary of the invention

[0005] The purpose of the present invention is to overcome or at least alleviate the deficiencies of the above-mentioned prior art and to provide a stator core with a simple structure and good cooling effect.

[0006] According to a first aspect of the present invention, there is provided a stator core, which comprises a first core unit, a second lamination and a third lamination, wherein:

[0007] At least one second lamination is respectively disposed at two axial ends of the first core unit, and at least one third lamination is disposed at the end of the second lamination facing away from the first core unit.

[0008] A plurality of first channels for passing the coolant in the axial direction of the stator core are formed in the first core unit, and the plurality of first channels are spaced apart in the circumferential direction of the stator core.

[0009] The second lamination is formed with a plurality of slots penetrating in the axial direction, the number of the slots is less than the number of the first channels, and each of the slots is connected to more than one of the first channels.

[0010] The third lamination is formed with a plurality of outlet holes extending in the axial direction, the number of the outlet holes being equal to the number of the slots, each of the outlet holes being connected to one of the slots, wherein a pair of slots and outlet holes connected to each other satisfy:

[0011] The outlet hole is located at the radially innermost region of the slot, and when the stator core is placed horizontally,

[0012] For the slots located in the lower semicircular portion of the core, the communicating outlet holes are located at the highest position of the slots.

[0013] In at least one embodiment, the groove includes an arcuate portion and an inner extension portion.

[0014] On a cross section perpendicular to the axial direction of the stator core, the area where the arc portion is located covers the area where multiple first channels connected to the slot are located, and the inner extension portion is connected to the arc portion on the radial outside and extends radially inward, and is connected to the outlet hole connected to the slot on the radial inside.

[0015] In at least one embodiment, when the stator core is placed horizontally, the slot extending to the lower semicircular portion of the core and the outlet hole connected to the slot meet the following conditions:

[0016] The outlet hole is higher than the area where the arc-shaped portion of the groove is located.

[0017] In at least one embodiment, when the stator core is placed horizontally, on a cross section perpendicular to the axial direction of the stator core, except for the slot located directly below the center of the cross section circle, any two slots adjacent in the circumferential direction satisfy the following conditions:

[0018] The first ray is obtained by connecting the lowermost end of the arc-shaped portion of the groove located at the top and the center of the cross-sectional circle, the second ray is obtained by connecting the uppermost end of the arc-shaped portion of the groove located at the bottom and the center of the cross-sectional circle, and the third ray is obtained by connecting the radial innermost end of the inner extension of the groove located at the bottom and the center of the cross-sectional circle. The third ray is located within the angle formed by the first ray and the second ray.

[0019] In at least one embodiment, when the stator core is placed horizontally, on a cross section perpendicular to the axial direction of the stator core, for a slot located directly below the center of a cross-sectional circle: the extension direction of the inner extension points to the center of the cross-sectional circle.

[0020] In at least one embodiment, when the stator core is placed horizontally, for the slot that does not extend to the lower semicircular portion of the core, and the outlet hole connected to the slot, the following conditions are satisfied:

[0021] The outlet hole is not higher than the area where the arc-shaped portion of the groove is located.

[0022] In at least one embodiment, when the stator core is placed horizontally, on a cross section perpendicular to the axial direction of the stator core, for the slots that do not extend to the lower semicircular portion of the core, the connection between the inner extension of the slot and the arc portion is located at the highest point of the arc portion.

[0023] In at least one embodiment, there are multiple third laminations located at at least one axial end of the first core unit, and multiple outlet holes communicating with at least one of adjacent third laminations are not aligned in the radial direction, and the outlet holes closer to the axial end are more biased toward the radial inside.

[0024] In at least one embodiment, the outer circumferential surface of the first core unit is partially recessed in the axial middle region to form an annular inlet channel, and the inlet channel is in communication with the plurality of first channels.

[0025] In at least one embodiment, the first core unit includes a plurality of first laminations and a plurality of fourth laminations, wherein the plurality of fourth laminations are stacked together to form an intermediate lamination, and a plurality of first laminations are stacked on both axial sides of the intermediate lamination, and the outer diameter of the fourth lamination is smaller than the outer diameter of the first lamination, so that the inlet channel is formed on the outer periphery of the fourth lamination.

[0026] The first stack is formed with a plurality of first holes penetrating in the axial direction, and the plurality of first holes penetrating in the axial direction form the first channel.

[0027] The stator core according to the present invention can spray the coolant to the winding package at the end of the core without using an oil spray ring, and the winding package can be evenly cooled at all locations in the circumferential direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of a stator assembly including a stator core according to one embodiment of the present application.

[0029] Figure 2 yes Figure 1 Schematic diagram of a section perpendicular to the axial direction.

[0030] Figure 3 yes Figure 1 Schematic diagram of a radial section.

[0031] Figure 4 yes Figure 1 In the schematic diagram of the second lamination cut perpendicularly to the axial direction, the first hole S10 and the outlet hole S30 are shown together for easy observation. It should be understood that in the cross section, the first hole S10 and the outlet hole S30 can only be observed separately along two different directions in the axial direction.

[0032] Figure 5 is a half of a cross-sectional view of a stator assembly including a stator core according to one embodiment of the present application. It should be understood that Figure 5 The posture of the stator assembly in the figure does not represent the state of the stator assembly in actual work. The figure shows the actual working posture of the stator assembly after rotation adjustment.

[0033] Figure 6 is a schematic diagram of a stator assembly including a stator core according to one embodiment of the present application.

[0034] Figure 7 yes Figure 6 A locally enlarged schematic diagram.

[0035] Description of reference numerals:

[0036] S1 first lamination; S10 first hole; S2 second lamination; S20 slot; S21 arc portion; S22 inner extension; S3 third lamination; S30 outlet hole; S4 fourth lamination; C1 inlet channel; C2 first channel; C3 second channel; C4 outlet channel;

[0037] W wire package; O1 reference circle; H1 main welding area; H2 auxiliary welding area. DETAILED DESCRIPTION

[0038] The exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present invention, and are not intended to exhaust all possible modes of the present invention, nor to limit the scope of the present invention.

[0039] Reference Figures 1 to 4 , a stator core according to an embodiment of the present application is introduced.

[0040] Unless otherwise specified, the radial, axial and circumferential directions of the components described below are all based on the radial, axial and circumferential directions of the stator core.

[0041] Figure 1 The stator assembly includes a stator core and a winding, wherein the winding forms a coil W at two axial ends of the stator core, and the winding may be a round wire with a circular cross section or a flat wire with a substantially rectangular cross section.

[0042] The stator core is formed by stacking four types of laminations, including a first lamination S1, a second lamination S2, a third lamination S3 and a fourth lamination S4. The first lamination S1 and the fourth lamination S4 constitute the main body of the stator core (hereinafter also referred to as the main body stack). A plurality of fourth laminations S4 are stacked together and arranged in the axial middle area of ​​the stator core to form an intermediate stack, and the number of fourth laminations S4 is, for example, 3 to 8. The first laminations S1 are stacked in two groups, and a group of multiple first laminations S1 are provided at each axial end of the intermediate stack. One or more second laminations S2 are provided at each axial end of the main body stack. One or more third laminations S3 are provided at the end of each side of the second lamination S2 away from the main body stack. Figure 1Only the approximate position of each laminate is shown. In the case where multiple laminates are stacked together, the multiple laminates are only shown as a whole, without showing the details of each laminate in the multiple laminates.

[0043] The outer diameter of the fourth laminate S4 is smaller than that of the first laminate S1, so that the main laminate forms an annular groove on the outer periphery of the middle laminate, which constitutes the inlet channel C1 for the coolant to flow into the core. The inlet channel C1 is closed on the outer periphery by, for example, the motor housing, which is not shown in the figure.

[0044] A plurality of first holes S10 distributed in the circumferential direction are formed on the first stack S1. In this embodiment, 96 first holes S10 are formed on each first stack S1. The first holes S10 of the first stacks S1 adjacent in the axial direction are connected to each other to form a first channel C2. The distance between the first hole S10 and the center of the first stack S1 is greater than the outer diameter of the fourth stack S4, so that when the first stack S1 and the fourth stack S4 are stacked together, the end opening of the first channel C2 is not covered by the fourth stack S4, or the inlet channel C1 is connected to the first channel C2. Therefore, the coolant flowing into the inlet channel C1 can be distributed in the circumferential direction along the inlet channel C1 and flow into each first channel C2. Figures 1 to 3 The dashed arrows in FIG. 1 show the approximate direction of the coolant.

[0045] A plurality of slots S20 distributed in the circumferential direction are formed on the second lamination S2. The number of slots S20 on each second lamination S2 is less than the number of first holes S10 on each first lamination S1. In this embodiment, 16 slots S20 are formed on each second lamination S2. Each slot S20 is connected to a plurality of first holes S10 in the axial direction. In this embodiment, each slot S20 is connected to a group of 6 first holes S10 located in the first lamination S1 at one end. The slot S20 is also connected to the outlet hole S30 located in the third lamination S3 on the other side of the axial direction, and each slot S20 is connected to an outlet hole S30. One or more slots S20 stacked in the axial direction (when a plurality of second laminations S2 are provided at the end of the main body stack) form a second channel C3, and the second channel C3 is used to connect the first channel C2 and the outlet channel C4. The outlet channel C4 is composed of one or more outlet holes S30 stacked in the axial direction (when a plurality of third laminations S3 are stacked).

[0046] The slot S20 includes an arc portion S21 and an inner extension portion S22. The arc portion S21 is arc-shaped and extends along the circumference of the stator core; the inner extension portion S22 is straight slot-shaped and extends along the approximate radial direction of the stator core (the extension direction of the inner extension portion at different circumferential positions is slightly deviated and not completely along the radial direction).

[0047] The shapes of the arcuate portions S21 of the multiple grooves S20 formed on the second laminate S2 are basically the same, but the directions of the inner extension portions S22 of the multiple grooves S20 and the connection positions with the arcuate portions S21 are different. This is because each groove S20 or second channel C3 plays the role of converging the coolant from the multiple first channels C2 into one outlet channel C4. Therefore, on the cross section perpendicular to the axial direction, the arcuate portion S21 covers the multiple first channels C2 to converge the coolant from the multiple first channels C2; and the inner extension portion S22 guides the converged coolant to the outlet channel C4 or the outlet hole S30.

[0048] For the plurality of outlet holes S30 on the third laminate S3, they are located at substantially the same position in the radial direction, for example, Figure 4 , these multiple outlet holes S30 are all located on the reference circle O1, and the radius of the reference circle O1 is slightly larger than the outer diameter of the coil W. However, in the circumferential direction, these multiple outlet holes S30 are not evenly distributed. Taking the normal working state of the stator, that is, the axial horizontal state, as a reference, on the cross section perpendicular to the axial direction, the outlet holes S30 located at the upper part are more densely distributed (the spacing angle between adjacent outlet holes S30 is smaller), and the outlet holes S30 located at the lower part are more sparsely distributed (the spacing angle between adjacent outlet holes S30 is larger). This is because the coolant flowing out of the outlet holes S30 located at the upper part can flow through the coil W below under the action of gravity. Therefore, the coil W closer to the lower part can be passed by more coolant. Through the uneven setting of the outlet holes S30 in the circumferential direction, the cooling effect of each part of the coil W can be made more uniform.

[0049] Next, the specific shapes of the arc portion S21 and the inner extension portion S22 of the groove S20 are introduced.

[0050] In a cross section perpendicular to the axial direction of the stator core, a plurality of first holes S10 communicating with the same slot S20 are connected together, that is, a general shape of an arc-shaped portion S21 is formed.

[0051] As for the inner extension S22, in order to allow the coolant discharged from the outlet channel C4 to impact the nearby coil W with sufficient pressure and flow rate, the inner extension S22 is divided into two types. Figure 4 The first type is for the slots S20 located in the upper semicircular portion of the stator cross section, and the second type is for the slots S20 located in the lower half of the stator cross section.

[0052] by Figure 4In the figure, the slots S20 located in the left semicircular part of the stator cross section are introduced, and it should be understood that the slots S20 located in the right semicircular part of the stator cross section are similar or symmetrical to the slots S20 in the left semicircular part. Among the slots S20 in the left semicircular part, the first type of slots S20 are the slots coded a, b, c, and d in the figure, and the second type of slots S20 are the slots coded e, f, g, h, and i in the figure.

[0053] For the first type of slots S20, since they are located in the upper semicircle, the collected coolant has a large gravitational potential energy, and these slots S20 are located above the windings W around them, so the inner extensions S22 corresponding to these slots only need to guide the coolant to the area close to the windings W. In this embodiment, the inner extension S22 of the first type of slots S20 is connected to the arc portion S21 at the highest point of the arc portion S21 (when the stator core is placed axially horizontally). Preferably, this type of inner extension S22 is centripetal as a whole, and the extension direction of the inner extension S22 points to the center of the cross-sectional circle. The radial innermost end of the inner extension S22, or the outlet hole S30 connected to the inner extension S22, is not higher than the area where the arc portion S21 is located.

[0054] For the second type of slots S20, since they are located in the lower semicircle, the gravitational potential energy of the collected coolant is relatively small, and these slots S20 are located at a lower position relative to the surrounding coils W. In order to effectively spray the coolant from these slots S20 to the surrounding coils W, in this embodiment, the extension direction of the inner extension S22 of the second type of slots S20 is upward and radially inward relative to the arc-shaped portion S21 connected thereto. In addition, except for the slot S20 located at the lowest point, the junction of the inner extension S22 of the other slots S20 and the arc-shaped portion S21 is also located at the highest point of the arc-shaped portion S21.

[0055] Specifically, Figure 4 Taking the slot S20 with the code e in the figure as an example, since part of the slot extends to the lower semicircle of the cross section, it is defined as the second type of slot. The inner extension S22 of the slot intersects with the arc portion S21 at the highest point of the arc portion S21 on the radial outer side, and the position extending to the innermost radial side, that is, the position of the outlet hole S30 connected to the slot S20, meets the following position characteristics:

[0056] The first ray OD is obtained by connecting the lowermost end of the arc-shaped portion S21 of the adjacent slot S20 No. d above the slot S20 No. e, i.e., point D, and the center of the stator core, i.e., point O; the second ray OE is obtained by connecting the uppermost end of the arc-shaped portion S21 of the slot S20 No. e, i.e., point E, and the center of the stator core, i.e., point M; the third ray OM is located within the angle ∠EOD formed by the first ray OD and the second ray OE, by connecting the exit hole S30 (or the radial innermost end of the inner extension S22) communicating with the slot S20 No. e, i.e., point M, and the center of the stator core, i.e., point O; the third ray OM is located within the angle ∠EOD formed by the first ray OD and the second ray OE. Optionally, the third ray OM is located on the bisector of the angle ∠EOD formed by the first ray OD and the second ray OE. In addition, point M where the exit hole S30 is located is the highest point of the slot S20 No. e.

[0057] For another example, referring to the above-mentioned position determination method, by observing grooves g and h, it can be found that the radial innermost endpoint N of the inner extension S22 of groove h is located on the bisector of the angle ∠GOH formed by the adjacent endpoints of the two arc-shaped portions S21 of the two adjacent grooves.

[0058] It is worth noting that, in actual applications, the line connecting the radial innermost endpoint of the inner extension S22 of the second type of groove S20 and the center O is not always located on the angular bisector of the auxiliary angle formed by the auxiliary line made above. For example, when buckle point riveting is used between the laminations, the radial innermost endpoint of the inner extension S22 needs to avoid the buckle point and be set at other positions within the auxiliary angle.

[0059] Among the second type of grooves S20, there is a groove with a special position, namely the groove S20 labeled i in the figure, which is located at the lowest point or directly below the center of the cross-sectional circle. The inner extension S22 of the groove S20 labeled i extends roughly in the vertical direction, and the inner extension S22 intersects with the arc-shaped portion S21 at the lowest point of the arc-shaped portion S21, and the extension direction of the inner extension S22 points to the center of the cross-sectional circle.

[0060] Through the asymmetric arrangement of the inner extension S22 and the arc-shaped portion S21, the coolant in the groove S20 located in the lower semicircle of the cross section can be guided to a higher position on the one hand, so that the wire package W below the groove S20 can be sprayed with more coolant; on the other hand, the coolant is prevented from being guided to a too high position by the inner extension S22 and weakening its injection pressure. In addition, although this arrangement of the present application does not make the coolant uniformly ejected in the circumferential direction, the gravity of the coolant can make the cooling effect of the wire package W more uniform.

[0061] Optionally, refer to Figure 5In the case where there are multiple third laminations S3 at the axial end of the core, the multiple interconnected outlet holes S30 forming one outlet channel C4 are not completely aligned in the radial direction, and the radial position of the outlet hole S30 closer to the axial end is closer to the inner side, so that the outlet channel C4 is slightly inclined in the radial direction, so that the emitted coolant can be sprayed to the nearby coil W in a more accurate posture. It should be understood that the multiple outlet channels C4 distributed on the circumference may not all be inclined, for example, the outlet channel C4 at the highest position may extend horizontally, because the coolant flowing out at a high position is more likely to fall to the coil W under the action of gravity; and the outlet channel C4 at a lower position, especially at the lower semicircular part of the stator cross section, is more suitable for being set to be inclined.

[0062] Next, refer to Figure 6 and Figure 7 , the arrangement of the welds between the laminations in this embodiment is introduced.

[0063] There are multiple axially extending recessed gaps distributed on the core body, and welding is performed at the gaps, which are often referred to as welds in the industry. The welding at the welds makes the adjacent laminations more firmly connected together. The welds in this embodiment include a main welding area H1 and a secondary welding area H2, and the main welding area H1 and the secondary welding area H2 are arranged at intervals in the circumferential direction.

[0064] The main welding area H1 completely penetrates the core in the axial direction, so that the first lamination S1, the second lamination S2, the third lamination S3 and the fourth lamination S4 can be connected together. The portion of the main welding area H1 in the inlet channel C1 is lower than the radial height of the inlet channel C1, and the coolant in the inlet channel C1 will not be blocked by the main welding area H1 and cannot flow in the circumferential direction. The height of the main welding area H1 in the end area where the first lamination S1, the second lamination S2 and the third lamination S3 are located is slightly greater than the height of the main welding area H1 in the inlet channel C1, so that the weld can be blocked at the end to prevent the coolant in the inlet channel C1 from flowing away along the weld in large quantities. It should be understood that the main welding area H1 can still form a smaller first weld gap H10 in the end area where the first lamination S1, the second lamination S2 and the third lamination S3 are located to leave enough welding margin. The radial dimension of the first weld notch H10 is not greater than 0.5 mm to prevent a large amount of coolant from overflowing from the first weld notch H10. It should be understood that a small amount of coolant overflowing from the first weld notch H10 to the end of the core is allowed.

[0065] The auxiliary welding area H2 does not extend to the inlet channel C1 in the axial direction, and the auxiliary welding area H2 is used to assist in connecting the first laminate S1, the second laminate S2 and the third laminate S3. Since the auxiliary welding area H2 does not enter the inlet channel C1 and does not block the inlet channel C1, the auxiliary welding area H2 can have a relatively high height to prevent a large amount of coolant from flowing to the periphery of the auxiliary welding area H2 (this area constitutes the second weld gap H20) and eventually overflowing. It should also be understood that in order to leave enough welding margin, a smaller second weld gap H20 is generally present, and the radial size of the second weld gap H20 is not greater than 0.5 mm. It is allowed for a small amount of coolant to overflow from the second weld gap H20 to the end of the core.

[0066] It should be understood that the above-mentioned embodiments and some aspects or features thereof may be appropriately combined.

[0067] The present invention has at least one of the following advantages:

[0068] (i) The second channel C3 formed by the groove S20 provided in the present application enables the coolant to be gathered therein and the pressure to be adjusted, so as to be sprayed with sufficient pressure to the end coil W. The stator assembly according to the present application may not be provided with an oil spray ring.

[0069] (ii) The inner extensions S22 of the plurality of grooves S20 are arranged asymmetrically in the circumferential direction to provide suitable flow guidance for the coolant at different positions of the cross-sectional circle, so that the coil can obtain a uniform cooling effect at different circumferential positions and the coolant has sufficient injection pressure.

[0070] (iii) When there are multiple third laminates S3, the multiple outlet holes S30 connected to each other may not be completely aligned in the radial direction, so that the outlet channel C4 is not parallel to the axial direction, but is inclined radially inward along the direction of coolant outflow, so that the coolant can gather toward the winding package and be sprayed more toward the winding package.

[0071] Of course, the present invention is not limited to the above-mentioned embodiments, and those skilled in the art can make various modifications to the above-mentioned embodiments of the present invention under the guidance of the present invention without departing from the scope of the present invention. For example:

[0072] (i) For similar laminations located at different positions in the axial direction, the communicating holes of two similar laminations adjacent in the axial direction may not be aligned in the radial direction or in the circumferential direction. For example, the communicating first holes on adjacent first laminations may not be aligned in the circumferential direction, so that the coolant is more evenly distributed in the circumferential direction of the entire core.

[0073] (ii) The axial partial sections of the core (eg the sections where the first and fourth laminations are located) may not be completely formed by stacking laminations, but may be formed by pressing soft magnetic materials, for example.

Claims

1. A stator core, comprising a first core unit, a second lamination (S2) and a third lamination (S3), characterized in that: At least one second lamination (S2) is respectively provided at two axial ends of the first core unit, and at least one third lamination (S3) is provided at the end of the second lamination (S2) facing away from the first core unit. A plurality of first channels (C2) for passing the coolant in the axial direction of the stator core are formed in the first core unit, and the plurality of first channels (C2) are spaced apart in the circumferential direction of the stator core. The second laminate (S2) is formed with a plurality of slots (S20) penetrating in the axial direction, the number of the slots (S20) is less than the number of the first channels (C2), and each of the slots (S20) is connected to more than one of the first channels (C2). The third laminate (S3) is formed with a plurality of outlet holes (S30) penetrating in the axial direction, the number of the outlet holes (S30) is equal to the number of the grooves (S20), each of the outlet holes (S30) is connected to one of the grooves (S20), wherein a pair of grooves (S20) and outlet holes (S30) connected to each other satisfy: The outlet hole (S30) is located in the radial innermost region of the slot (S20), and when the stator core is placed horizontally, For the slot (S20) located in the lower semicircular portion of the core, the connected outlet hole (S30) is located at the highest position of the slot (S20). The groove (S20) comprises an arc portion (S21) and an inner extension portion (S22). On a cross section perpendicular to the axial direction of the stator core, an area where the arc-shaped portion (S21) is located covers an area where a plurality of first channels (C2) connected to the slot (S20) are located, and the inner extension portion (S22) is connected to the arc-shaped portion (S21) on the radial outside and extends radially inward, and is connected to an outlet hole (S30) connected to the slot (S20) on the radial inside.

2. The stator core according to claim 1, characterized in that: When the stator core is placed horizontally, the slot (S20) extending to the lower semicircular portion of the core and the outlet hole (S30) connected to the slot (S20) satisfy the following conditions: The outlet hole (S30) is higher than the area where the arc-shaped portion (S21) of the groove (S20) is located.

3. The stator core according to claim 2, characterized in that: When the stator core is placed horizontally, on a cross section perpendicular to the axial direction of the stator core, except for the slot (S20) located directly below the center of the cross section circle, any two slots (S20) adjacent to each other in the circumferential direction satisfy the following conditions: A first ray is obtained by connecting the lowermost end of the arc-shaped portion (S21) of the upper groove (S20) and the center of the cross-sectional circle, a second ray is obtained by connecting the uppermost end of the arc-shaped portion (S21) of the lower groove (S20) and the center of the cross-sectional circle, and a third ray is obtained by connecting the radial innermost end of the inner extension (S22) of the lower groove (S20) and the center of the cross-sectional circle. The third ray is located within the angle formed by the first ray and the second ray.

4. The stator core according to claim 2, characterized in that: When the stator core is placed horizontally, on a cross section perpendicular to the axial direction of the stator core, for the slot (S20) located directly below the center of the cross section circle: the extension direction of the inner extension (S22) points to the center of the cross section circle.

5. The stator core according to claim 1, characterized in that: When the stator core is placed horizontally, the slot (S20) that does not extend to the lower semicircular portion of the core, and the outlet hole (S30) connected to the slot (S20) meet the following conditions: The outlet hole (S30) is not higher than the area where the arc-shaped portion (S21) of the groove (S20) is located.

6. The stator core according to claim 5, characterized in that: When the stator core is placed horizontally, on a cross section perpendicular to the axial direction of the stator core, for the slot (S20) that does not extend to the lower semicircular portion of the core, the connection between the inner extension (S22) of the slot (S20) and the arc-shaped portion (S21) is located at the highest point of the arc-shaped portion (S21).

7. The stator core according to claim 1, characterized in that: There are a plurality of third laminations (S3) located at at least one axial end of the first core unit, and a plurality of outlet holes (S30) communicating at least one of adjacent third laminations (S3) are not aligned in the radial direction, and the outlet holes (S30) closer to the axial end are more inclined to the radial inside.

8. The stator core according to any one of claims 1 to 7, characterized in that: The outer peripheral surface of the first core unit is partially recessed in the axial middle region to form an annular inlet channel (C1), and the inlet channel (C1) is connected to the plurality of first channels (C2).

9. The stator core according to claim 8, characterized in that: The first core unit comprises a plurality of first laminations (S1) and a plurality of fourth laminations (S4), wherein the plurality of fourth laminations (S4) are stacked together to form an intermediate lamination, and a plurality of first laminations (S1) are stacked on both axial sides of the intermediate lamination, and the outer diameter of the fourth lamination (S4) is smaller than the outer diameter of the first lamination (S1), so that the inlet channel (C1) is formed on the outer periphery of the fourth lamination (S4). The first laminate (S1) is formed with a plurality of first holes (S10) penetrating in the axial direction, and the plurality of first holes (S10) penetrating in the axial direction form the first channel (C2).

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