Stator structure and motor

Abstract

The utility model relates to a stator structure and a motor. The stator structure includes a stator assembly and a sealing member. The stator assembly comprises a stator core with a stator slot, and the stator slot comprises a first opening and a second opening. The sealing element comprises a first sealing part and a second sealing part, and the first sealing part is used for sealing at least part of the first opening of the stator groove to form a through channel; and the second sealing part is arranged at at least one end of the first sealing part and is provided with a first inlet which is at least partially communicated with the second opening of the stator slot. According to the stator structure, the stator assembly can be directly cooled when the cooling liquid passes through the closed channel, no extra parts are needed, the structure is simplified, and the cooling effect is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of motors, and in particular, to a stator structure and a motor. Background Art

[0002] With the continuous development of new energy vehicles and the gradual increase in market demand for the driving capabilities of new energy vehicles, the drive motors of new energy vehicles need to continuously improve the speed, torque density and power density while gradually compressing the volume. The higher the speed, torque density and power density of the motor, the higher the heat it generates. Therefore, the heat dissipation and cooling structure of the motor are essential for the reliable, stable and efficient operation of the motor.

[0003] In the related art, a rotor shaft is usually used to cool the rotor assembly of the motor by setting a cooling oil channel inside the rotor shaft. At the same time, part of the cooling oil can only cool the end of the stator core, and the cooling effect is limited. Utility Model Content

[0004] The purpose of the present disclosure is to provide a stator structure and a motor, wherein the stator structure can directly cool the stator assembly when the coolant passes through a closed channel, without the need for additional components, thereby simplifying the structure and improving the cooling effect.

[0005] In order to achieve the above objectives, the present disclosure provides a stator structure in a first aspect, including:

[0006] A stator assembly comprising a stator core having stator slots, the stator slots comprising a first opening and a second opening; and

[0007] The sealing member comprises a first sealing portion and a second sealing portion, wherein the first sealing portion is used to seal at least part of the first opening of the stator slot to form a through passage; the second sealing portion is arranged at at least one end of the first sealing portion and is provided with a first inlet at least partially connected to the second opening of the stator slot.

[0008] Optionally, the first sealing portion corresponds to the first opening one by one; and / or

[0009] The first inlet corresponds to the second opening one by one.

[0010] Optionally, the second sealing portion is constructed as an annular structure and is arranged to fit the end surface of the stator core.

[0011] Optionally, the first inlet includes a first notch and a second notch, the first notch corresponds to the second opening, the second notch is located on a side of the first notch away from the second opening, and a size of the second notch is larger than a size of the first notch.

[0012] Optionally, the sealing member further comprises a third sealing portion, which is arranged on a side of the second sealing portion away from the first sealing portion and is used for sealingly connecting with a housing of the motor.

[0013] Optionally, the seal and the stator core are integrally injection molded.

[0014] Optionally, the sealing element is made of thermoplastic material.

[0015] Optionally, the stator assembly further includes a stator winding, wherein the stator winding is disposed inside the stator slot, and a cooling channel for circulating a coolant is formed between the stator winding and the stator slot.

[0016] Optionally, a groove portion facing away from the side wall of the stator slot is formed on the stator winding, and the cooling channel is formed between the groove portion and the side wall of the stator slot.

[0017] In a second aspect of the present disclosure, a motor is further provided, the motor comprising a housing, an end cover, a rotor assembly and the above-mentioned stator structure;

[0018] The stator structure and the rotor assembly are arranged inside a cavity surrounded by the housing and the end cover;

[0019] The housing is provided with a liquid inlet;

[0020] The end cover comprises an extension portion; the sealing member, the extension portion and the shell form a liquid storage cavity which is in communication with the first inlet and the liquid inlet.

[0021] Through the above technical solution, i.e., the stator structure of the present disclosure, the first opening of the stator slot is sealed by the first sealing part of the seal, so that a through channel for installing the stator assembly and circulating the coolant can be formed between the stator winding and the stator slot, and the second sealing part seals at least one end of the stator core and forms a first inlet connected to the second opening of the stator slot for the coolant to enter the through channel. The stator structure is provided with a seal on the stator core to seal the first opening and the second opening of the stator slot to form a through channel for the coolant to cool the stator assembly, which can prevent the coolant from entering the air gap between the stator assembly and the rotor assembly, so that the coolant can directly cool the stator assembly without the need for additional components, simplifying the structure and improving the cooling effect.

[0022] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0024] Figure 1 It is a structural diagram of a stator structure provided in some embodiments of the present disclosure.

[0025] Figure 2 is a structural diagram of a seal of a stator structure provided in some embodiments of the present disclosure.

[0026] Figure 3 is a side view of a seal of a stator structure provided by some embodiments of the present disclosure.

[0027] Figure 4 It is a partial structural diagram of a stator structure provided in some embodiments of the present disclosure, in which a first inlet is illustrated.

[0028] Figure 5 It is a partial cross-sectional view of the stator structure provided in some embodiments of the present disclosure, wherein the cutting plane is a plane perpendicular to the axial direction, and the stator winding is not shown.

[0029] Figure 6 It is a partial cross-sectional view of a stator structure provided in some embodiments of the present disclosure, wherein the cutting plane is a plane perpendicular to the axial direction, showing the stator winding.

[0030] Figure 7 It is a schematic diagram of the structure of the motor provided in some embodiments of the present disclosure.

[0031] Figure 8 is based on Figure 7 A partial enlarged view of .

[0032] Fig. 9 It is a schematic diagram of the coordination between the stator winding and the seal provided in some embodiments of the present disclosure.

[0033] Description of Reference Numerals

[0034] 10-stator structure; 101-accommodating cavity; 102-liquid storage cavity; 110-housing; 111-liquid inlet; 120-end cover; 121-extension part; 1211-sealing groove; 1212-sealing ring; 122-insulating layer;

[0035] 200-stator assembly; 201-cooling channel; 202-through channel; 210-stator core; 211-stator slot; 2111-first opening; 2112-second opening; 220-stator winding; 221-copper wire; 2211-groove portion;

[0036] 300-seal; 310-first seal; 320-second seal; 321-first inlet; 3211-first notch; 3212-second notch; 330-third seal;

[0037] 400-insulation paper;

[0038] 500-Rotor assembly. DETAILED DESCRIPTION

[0039] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0040] In the present disclosure, unless otherwise specified, directional words such as "up, down, left, right" generally refer to up, down, left, right relative to the accompanying drawings; "inside and outside" refer to the inside and outside of the outline of the corresponding component; "far and near" refer to the corresponding structure or the corresponding component being far away from or close to another structure or component. In addition, the terms "first", "second", etc. used in the present disclosure are to distinguish one element from another and do not have order and importance. In addition, in the following description, when referring to the drawings, unless otherwise explained, the same figure numbers in different drawings represent the same or similar elements. The above definitions are only used to explain and illustrate the present disclosure and should not be construed as limitations on the present disclosure.

[0041] The purpose of the present disclosure is to provide a stator structure 10 and a motor, wherein the stator structure 10 can achieve direct cooling of a stator assembly 200 (including a stator core 210 and a stator winding 220 ) without the need for additional components, thereby simplifying the structure and improving the cooling effect.

[0042] In order to achieve the above purpose, Figures 1 to 9 As shown, an embodiment of the present disclosure provides a stator structure 10, which includes a stator assembly 200 and a seal 300. The stator assembly 200 includes a stator core 210 having a stator slot 211, and the stator slot 211 includes a first opening 2111 and a second opening; the seal 300 includes a first sealing portion 310 and a second sealing portion 320, the first sealing portion 310 is used to seal at least part of the first opening 2111 of the stator slot 211 to form a through channel 202; the second sealing portion 320 is provided at at least one end of the first sealing portion 310, and is provided with a first inlet 321 at least partially connected to the second opening 2112 of the stator slot 211.

[0043] Through the above technical solution, i.e., the stator structure 10 of the present disclosure, the first opening 2111 of the stator slot 211 is sealed by the first sealing portion 310 of the sealing member 300, so that a through channel 202 for installing the stator assembly 200 and circulating the coolant can be formed between the stator winding 220 and the stator slot 211, and the second sealing portion 320 seals at least one end of the stator core 210, and forms a first inlet 321 in communication with the second opening 2112 of the stator slot 211, for the coolant to enter the through channel 202. The stator structure 10 is provided with a sealing member 300 on the stator core 210 to seal the first opening 2111 and the second opening 2112 of the stator slot 211 to form a through channel 202 for cooling the stator assembly 200 with the coolant, so that the coolant can be prevented from entering the air gap between the stator assembly 200 and the rotor assembly 500, so that the coolant can directly cool the stator assembly 200, without the need for additional components, simplifying the structure, and improving the cooling effect.

[0044] There are multiple stator slots 211, which are arranged in the circumferential direction of the inner wall of the stator core 210. Each stator slot 211 includes a first opening 2111 and two second openings 2112 arranged on opposite sides of the stator slot 211 in the axial direction, wherein the first opening 2111 is an opening facing the rotor assembly 500, and the second openings 2112 are openings at both axial end surfaces of the stator core 210.

[0045] The first sealing portion 310 of the sealing member 300 seals the first opening 2111 of the stator slot 211, and the second sealing portion 320 can be arranged at opposite ends of the first sealing portion 310, and both are annular structures, arranged to fit the end surface of the stator core 210, and extending radially outward from the first sealing portion 310 along the stator core 210, and the second sealing portion 320 is provided with a first inlet 321 connected to the second opening 2112, which is used for the stator winding 220 to be installed in the stator slot 211, and at the same time, external coolant (cooling oil) can enter the through-channel 202 through the first inlet 321, wherein a cooling channel 201 is formed between the stator winding 220 and the inner wall of the stator slot 211 or between the stator winding 220 and the inner wall of the through-channel 202.

[0046] Optionally, the first sealing portion 310 corresponds to the first opening 2111 one by one; and / or, the first inlet 321 corresponds to the second opening 2112 one by one. In some embodiments, the inner side wall of the stator core 210 is circumferentially provided with a plurality of stator slots 211, and the sealing member 300 includes a plurality of first sealing portions 310 corresponding to the first openings 2111 of the stator slots 211 one by one, and the extension direction of the first sealing portion 310 is the same as the extension direction of the stator slots 211, and is used to seal the first openings 2111, so as to enclose the stator slots 211 into a through channel 202 with second openings 2112 at both ends. The second sealing portion 320 is provided at opposite ends of the first sealing portion 310, and both are configured as an annular structure, and are arranged in contact with the end surface of the stator core 210. The second sealing portion 320 is provided with a plurality of first inlets 321, and the first inlets 321 correspond to and communicate with the second openings 2112 one by one.

[0047] In the related art, the copper wire 221 of the stator winding 220 is easily damaged at the bottom during the twisting process. It is usually necessary to assemble a tooth guard between the bottom of the copper wire 221 and the stator end face before twisting to protect the copper wire 221, and the assembly process is complicated.

[0048] The first inlet 321 can be constructed using any suitable structure, such as Figure 3 and Figure 4 As shown, in some embodiments, the first inlet 321 includes a first notch 3211 and a second notch 3212 , the first notch 3211 corresponds to the second opening 2112 , the second notch 3212 is located on a side of the first notch 3211 away from the second opening 2112 , and the size of the second notch 3212 is larger than the size of the first notch 3211 .

[0049] Among them, the first inlet 321 provided in the second sealing part 320 includes a first notch 3211 and a second notch 3212. The height of the first notch 3211 is equivalent to the height of the insulating paper 400 in the motor slot, and is mainly used to ensure the air gap sealing in the motor stator slot 211. The second notch 3212 is slightly larger than the first notch 3211 (the second opening 2112 of the stator slot 211) and is higher than the insulating paper 400 by a distance. The main function is to act as a tooth guard used in the head twisting process during the production process of the stator assembly 200 to prevent the bottom of the copper wire 221 from being scratched or damaged by the stator core 210 and the insulating paper 400 during the twisting process. The two-layer notch structure is integrally injected during injection molding. Therefore, the seal 300 disclosed in the present invention can replace the torsion tooth guard in the processing technology of the stator assembly 200, which can simplify the stator processing technology.

[0050] It should be noted that the seal 300 further includes a third seal portion 330, which is disposed on a side of the second seal portion 320 away from the first seal portion 310, and is used to be sealed and connected with the housing 110 of the motor to form a liquid storage chamber 102 for storing coolant. The extension portion 121 of the end cover 120 of the motor is sealed and connected to the third seal portion 330, and then the second seal 300, the end cover 120 and the housing 110 are combined to form an oil storage chamber.

[0051] In order to better achieve the sealing effect between the first sealing member 300 and the extension portion 121, in some embodiments, a sealing structure is provided at the junction of the first sealing member 300 and the extension portion 121. When the first sealing member 300 includes the third sealing portion 330, the third sealing portion 330 and the extension portion 121 may be in an overlapping relationship, and the sealing structure may be provided between the extension portion 121 and the third sealing portion 330 for a sealed connection therebetween.

[0052] like Figure 5 As shown, in some embodiments, a sealing groove 1211 is formed on the side of the extension portion 121 facing the first sealing member 300, and a sealing ring 1212 or a sealing strip is installed in the sealing groove 1211 to seal the extension portion 121 with the first sealing member 300. Wherein, when the first sealing member 300 includes the first sealing portion 310, the second sealing portion 320 and the third sealing portion 330, the third sealing portion 330 is sleeved on the circumferential outer side of the extension portion 121, and the extension portion 121 is formed with the sealing groove 1211, and the sealing ring 1212 is installed in the sealing groove 1211, so that the extension portion 121 and the third sealing portion 330 can be sealed and connected.

[0053] In some embodiments, when the distance between the stator winding 220 and the end housing is small, in order to improve the insulation between the two, such as Figure 5 As shown, in some embodiments, the end cap 120 is provided with an insulating layer 122 at a position corresponding to the stator winding 220. Insulation spraying can be performed on the surface of the extension portion 121 facing the stator winding 220 and the surface of the end cap 120 facing the stator winding 220 to form the insulating layer 122. It should be noted that the surface of the end cap 120 can be subjected to insulation spraying according to the design to ensure electrical clearance, such as epoxy spraying, plastic injection molding, ceramic spraying, etc.

[0054] Optionally, the seal 300 is integrally injection molded with the stator core 210, that is, the stator core 210 is first processed and then integrally injection molded based on the stator core 210, so as to achieve the sealing of the through channel 202 in the stator slot 211. At the same time, the seal 300 can also cooperate with the shell assembly (including the end cover 120 and the shell 110) to form a liquid storage chamber 102 located at one end of the stator assembly 200.

[0055] The material of the seal 300 is preferably a high-strength, high-fluidity thermoplastic material, including but not limited to PPS (polyphenylene sulfide, a new high-performance thermoplastic resin with the advantages of high mechanical strength, high temperature resistance, chemical resistance, flame retardancy, good thermal stability, and excellent electrical properties.).

[0056] In some embodiments, the stator assembly 200 further includes a stator winding 220 , which is disposed inside the stator slot 211 , and a cooling channel 201 for circulating a coolant is formed between the stator winding 220 and the stator slot 211 . The stator assembly 200 includes a stator core 210 having a stator slot 211, and a stator winding 220, wherein the stator slot 211 includes a first opening 2111 and a second opening 2112; the seal 300 includes a first sealing portion 310 and a second sealing portion 320, wherein the first sealing portion 310 is used to seal at least part of the first opening 2111 of the stator slot 211; the second sealing portion 320 is disposed at at least one end of the first sealing portion 310 (in the embodiment disclosed herein, the second sealing portion 320 is disposed at opposite ends of the first sealing portion 310), and is provided with a first inlet 321 connected to the second opening 2112 of the stator slot 211; the stator winding 220 is disposed in the stator slot 211, and a cooling channel 201 for circulating coolant is formed between the stator winding 220 and the stator slot 211, so that the coolant directly cools the stator core 210 and the stator winding 220 when passing through the cooling channel 201.

[0057] like Figure 6 As shown, in some embodiments, a groove portion 2211 facing away from the side wall of the stator slot 211 is formed on the stator winding 220, and a cooling channel 201 is formed between the groove portion 2211 and the side wall of the stator slot 211. In particular, a groove portion 2211 is formed on the stator winding 220, and a cooling channel 201 is formed between the groove portion 2211 and the side wall of the stator slot 211. There can be multiple groove portions 2211, and each groove portion 2211 forms a cooling channel 201. Therefore, multiple cooling channels 201 can increase the contact area between the coolant and the stator core 210 and the stator winding 220, thereby improving the cooling effect.

[0058] In other embodiments, the side wall of the stator slot 211 is formed with a groove portion 2211 facing the stator winding 220, and a cooling channel 201 is formed between the groove portion 2211 and the stator winding 220. Similarly, the groove portion 2211 can be formed on the side wall of the stator slot 211, and the cooling channel 201 can be surrounded by the groove portion 2211 and the stator winding 220. Similarly, there can be multiple groove portions 2211, and multiple cooling channels 201 with better cooling capacity can be formed.

[0059] In some other embodiments, a groove portion 2211 facing away from the side wall of the stator slot 211 may be formed on the stator winding 220, and a groove portion 2211 facing away from the stator winding 220 may be formed on the side wall of the stator slot 211. Similarly, multiple cooling channels 201 may be formed for the coolant to pass through.

[0060] like Figure 6 As shown, in some embodiments, the stator winding 220 may include a plurality of copper wires 221 disposed in each stator slot 211, and at least one cooling channel 201 is provided between each copper wire 221 and the stator slot 211. The copper wire 221 may have a rectangular or approximately rectangular cross-section, and a groove portion 2211 may be formed on two opposite side walls of each copper wire 221 corresponding to the winding assembly, and the groove portion 2211 and the side wall of the stator slot 211 are used to enclose the cooling channel 201. For example, eight layers of copper wires 221 are arranged along the slot depth in each stator slot 211, and the groove portions 2211 are arranged on two opposite side surfaces of two adjacent copper wires 221. Of course, they may also be arranged on both side surfaces at the same time, or those skilled in the art may arrange the groove portions 2211 according to actual needs.

[0061] It should be noted that a groove portion 2211 may be provided on at least one side of two adjacent copper wires 221 facing the other copper wire 221, and a cooling channel 201 for the circulation of coolant may be formed. By cooling the copper wires 221 of the stator winding, the stator core 210 may also be indirectly cooled.

[0062] like Figure 7 , Figure 8 and Fig. 9 As shown, an embodiment of the present disclosure further provides a motor, which includes a housing 110 , an end cover 120 , a rotor assembly 500 and the above-mentioned stator structure 10 . Therefore, the motor also has all the advantages of the above-mentioned stator assembly 200 .

[0063] In some embodiments, the stator structure 10 (including the stator assembly 200 and the seal 300) and the rotor assembly 500 are arranged inside a cavity surrounded by a shell 110 and an end cover 120; the shell 110 is provided with a liquid inlet 111, and the end cover 120 includes an extension portion 121; the seal 300, the extension portion 121 and the shell 110 form a liquid storage cavity 102 connected to the first inlet 321 and the liquid inlet 111.

[0064] The seal 300 includes a first sealing portion 310 capable of sealing the first opening 2111 of the stator slot 211, and the seal 300 also includes a second sealing portion 320 extending to at least one side end surface of the stator core 210, and together with the motor housing 110 and the end cover 120, forms a liquid storage chamber 102 located inside the accommodating chamber 101 and connected to the first inlet 321 and the liquid inlet 111 on the housing 110. The liquid storage chamber 102 is also connected to the above-mentioned cooling channel 201, so that the coolant (such as cooling oil) can directly enter the cooling channel 201 to cool the stator core 210 and the stator winding 220 of the stator assembly 200.

[0065] The end cover 120 includes an extension portion 121 toward the inside of the cavity, and the seal 300, the extension portion 121 and the housing 110 enclose a liquid storage cavity 102. The end cover 120 is detachably and sealedly installed at the left opening of the housing 110, and the two form a cavity. The inner wall of the end cover 120 is formed with an extension portion 121 (specifically, it can be an annular structure) toward the stator core 210, and the extension portion 121 can be sealed and connected with the second sealing portion 320 of the seal 300, so that the liquid storage cavity 102 is formed between the end cover 120, the seal 300 and the housing 110, and the liquid storage cavity 102 is respectively connected with the liquid inlet 111 and the first inlet 321 (located on the left side of the cooling channel 201). It should be noted that in order to achieve better connection and sealing, in some embodiments, the seal 300 also includes a second sealing portion 320 away from the first sealing portion 310 and a third sealing portion 330 extending toward the end cover 120, and the extension portion 121 of the end cover 120 is sealed and connected to the third sealing portion 330, and then combined with the second sealing portion 320, the end cover 120 and the housing 110 to form an oil storage chamber.

[0066] The stator structure 10 and the motor disclosed herein form a cooling channel 201 between the stator core 210 and the seal 300 by forming the stator core 210 and the seal 300 in one piece. When the motor is oil-cooled, a necessary sealing structure (formed by the seal 300) is formed on the cooling channel 201 to ensure the cooling effect and prevent the coolant (cooling oil) from entering the air gap when the motor is running, thereby affecting the normal operation of the motor. Therefore, the seal 300 can ensure the cooling effect of the motor as a whole and improve the reliability and stability of the motor operation.

[0067] Furthermore, the copper wire 221 of the stator winding 220 of the motor is prone to bottom damage during the twisting process, and it is usually necessary to assemble a tooth guard between the bottom of the copper wire 221 and the stator end face before twisting to protect the copper wire 221. The seal 300 of the stator assembly 200 of the present disclosure forms a first inlet 321 with a first notch 3211 and a second notch 3212 in the second sealing portion 320, which can replace the twisting tooth guard in the stator processing process. In this way, there is no need to equip the copper wire 221 with an additional tooth guard during twisting, which can simplify the stator processing process.

[0068] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0069] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0070] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A stator structure, characterized in that: include: A stator assembly including a stator core having stator slots, the stator slots including a first opening and a second opening; and A sealing member, comprising a first sealing portion and a second sealing portion, wherein the first sealing portion is used to seal at least a portion of a first opening of the stator slot to form a through channel; The second sealing portion is disposed at at least one end of the first sealing portion and is provided with a first inlet at least partially communicated with the second opening of the stator slot.

2. The stator structure according to claim 1, characterized in that: The first sealing portion corresponds to the first opening one by one; and / or The first inlet corresponds to the second opening one by one.

3. The stator structure according to claim 1, characterized in that: The second sealing portion is constructed as an annular structure and is arranged to fit the end surface of the stator core.

4. The stator structure according to claim 1, characterized in that: The first inlet includes a first notch and a second notch, the first notch corresponds to the second opening, the second notch is located at a side of the first notch away from the second opening, and a size of the second notch is larger than a size of the first notch.

5. The stator structure according to claim 1, characterized in that: The sealing member further comprises a third sealing portion, which is arranged on a side of the second sealing portion away from the first sealing portion and is used for sealingly connecting with a housing of the motor.

6. The stator structure according to any one of claims 1 to 5, characterized in that: The sealing member and the stator core are integrally injection molded.

7. The stator structure according to claim 6, characterized in that: The sealing element is made of thermoplastic material.

8. The stator structure according to claim 1, characterized in that: The stator assembly further includes a stator winding, which is arranged inside the stator slot. A cooling channel for circulating a coolant is formed between the stator winding and the stator slot.

9. The stator structure according to claim 8, characterized in that: A groove portion facing away from the side wall of the stator slot is formed on the stator winding, and a cooling channel is formed between the groove portion and the side wall of the stator slot.

10. A motor, characterized in that: The motor comprises a housing, an end cover, a rotor assembly and a stator structure according to any one of claims 1 to 9; The stator structure and the rotor assembly are arranged inside a cavity surrounded by the housing and the end cover; The housing is provided with a liquid inlet; The end cover comprises an extension portion; the sealing member, the extension portion and the shell form a liquid storage cavity which is in communication with the first inlet and the liquid inlet.

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