Electric motor cooling system, electric motor, electric drive assembly system and vehicle

Abstract

The present disclosure relates to an electric motor cooling system. The electric motor cooling system comprises a rotor and a stator, wherein the stator comprises a stator core and a winding, the stator core being provided with an annular receiving groove at an outer periphery thereof, for the purpose of receiving oil supplied from an oil pump, and the stator being provided with a first channel for conveying the oil from the receiving groove to two ends of the stator, wherein the electric motor cooling system further comprises an isolating sleeve for isolating the rotor from the stator, wherein the isolating sleeve is provided with a sealing structure at a driving end of the electric motor, causing the oil to be conveyed from the driving end of the electric motor to a non-driving end of the electric motor.

Description

[0001] ELECTRIC MOTOR COOLING SYSTEM, ELECTRIC MOTOR, ELECTRIC DRIVE ASSEMBLY SYSTEM AND VEHICLE

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to an electric motor cooling system. The present disclosure further relates to an electric motor comprising such an electric motor cooling system, an electric drive assembly system comprising such an electric motor, and a vehicle comprising such an electric drive assembly system.

[0004] BACKGROUND

[0005] Electric motors used to drive vehicles usually have high power, and generate a large amount of heat when running continuously. If heat dissipation is insufficient, the heat generated will accumulate inside the electric motor, causing the temperature of the electric motor to rise and affecting the reliability and performance of the electric motor.

[0006] Methods of cooling electric motors in the prior art include oil cooling. In oil cooling, the stator and rotor are cooled with cooling oil, and although heat dissipation capacity is high, there is increased power consumption due to oil agitation losses, resulting in low overall efficiency. For this reason, a means for avoiding oil agitation losses has been proposed in the prior art: using an isolating sleeve to isolate the stator and rotor.

[0007] The stator consists of a core and windings; the stator winding is a coil that generates a magnetic field when energized, and is also the main generating source of heat inside the electric motor. When the electric motor is running, the stator windings are excited by current and gradually rise in temperature; the stator core transfers heat by conduction, while also being affected by the heat of the stator windings, so the stator temperature will also rise accordingly. When the temperature of the stator core is too high, this will result in damage to the insulation of the electric motor, thus affecting the service life and safety of the electric motor. The regions on the stator where the windings pass through are called slots, the regions that separate the slots are called teeth, and the part that connects all of the teeth is called the yoke (the region formed between the bottoms of the slots of the stator laminations, and an outer circle). The stator yoke is also a region where heating is more severe.

[0008] Thus, there is a need for an electric motor cooling system capable of fully cooling the stator windings and yoke while avoiding oil agitation losses.

[0009] SUMMARY OF THE INVENTION

[0010] Thus, the present disclosure is intended to solve the abovementioned problem, having the objective of providing a novel electric motor cooling system, an electric motor, an electric drive assembly system and a vehicle.

[0011] This objective is achieved by an electric motor cooling system according to an embodiment of the present disclosure, comprising: a rotor and a stator, wherein the stator comprises a stator core and a winding, the stator core being provided with an annular receiving groove at an outer periphery thereof, for the purpose of receiving oil supplied from an oil pump, and the stator being provided with a first channel for conveying the oil from the receiving groove to two ends of the stator, wherein the electric motor cooling system further comprises an isolating sleeve for isolating the rotor from the stator, wherein the isolating sleeve is provided with a sealing structure at a driving end of the electric motor, causing the oil to be conveyed from the driving end of the electric motor to a non-driving end of the electric motor.

[0012] In the electric motor cooling system according to the present disclosure, the stator and rotor are isolated by means of the isolating sleeve, avoiding oil agitation losses, and cooling oil can directly cool a stator yoke and the winding and fully infiltrate a winding end, resulting in better heat dissipation and better electric motor performance and efficiency.

[0013] The electric motor cooling system according to the present disclosure may also have one or more of the following features individually or in combination.

[0014] According to an embodiment of the present disclosure, the isolating sleeve further comprises an axially extending main body structure, the main body structure extending from the sealing structure to an end cover at the non-driving end of the electric motor.

[0015] According to an embodiment of the present disclosure, the first channels are distributed at intervals circumferentially and in fluid communication with the receiving groove.

[0016] According to an embodiment of the present disclosure, the stator core comprises two axially arranged first lamination sections and a second lamination section arranged between the two first lamination sections.

[0017] According to an embodiment of the present disclosure, the receiving groove is arranged on the second lamination section.

[0018] According to an embodiment of the present disclosure, at least a portion of the first channel is arranged on the first lamination section.

[0019] According to an embodiment of the present disclosure, the stator core further comprises an end lamination section arranged on a side, axially opposite the second lamination section, of each of the two first lamination sections, at least a portion of the first channel being arranged on the end lamination section.

[0020] According to an embodiment of the present disclosure, bolt holes for fasteners to pass through are arranged circumferentially on the first lamination section and the end lamination section.

[0021] According to an embodiment of the present disclosure, bolt holes are correspondingly arranged on the sealing structure of the isolating sleeve, and the first lamination section and end lamination section close to the driving end of the electric motor are fixed to the isolating sleeve by means of the fasteners.

[0022] According to an embodiment of the present disclosure, the stator is further provided with a second channel for conveying the oil from the receiving groove to the non-driving end of the electric motor, at least a portion of the second channel running through the bolt hole.

[0023] According to an embodiment of the present disclosure, stator tooth slots are arranged circumferentially on the stator core, an in-slot winding being inserted in the stator tooth slots, and the oil flowing from the driving end of the electric motor towards the non-driving end of the electric motor through the stator tooth slots of the stator core.

[0024] According to an embodiment of the present disclosure, the electric motor cooling system further comprises a housing, and the oil flows from the non-driving end of the electric motor into an oil collector through an oil outlet on the housing.

[0025] The present disclosure further relates to an electric motor comprising the electric motor cooling system described above.

[0026] The present disclosure further relates to an electric drive assembly system comprising the electric motor described above.

[0027] The present disclosure further relates to a vehicle comprising the electric drive assembly system described above.

[0028] BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The foregoing and other features and advantages of the present disclosure will become more apparent from the following detailed description of exemplary embodiments with reference to the accompanying drawings, and the description and the accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. The drawings below are not drawn to scale according to actual dimensions but rather focus on showing the main purpose of the present disclosure.

[0030] Fig. 1 shows an electric motor in an assembled state, comprising an electric motor cooling system according to an embodiment of the present disclosure.

[0031] Fig. 2 is an axial sectional view of the electric motor shown in Fig. 1.

[0032] Fig. 3 is an exploded view of the electric motor shown in Fig. 1.

[0033] Fig. 4A shows an isolating sleeve according to an embodiment of the present disclosure.

[0034] Fig. 4B shows an isolating sleeve according to another embodiment of the present disclosure.

[0035] Fig. 5 shows a stator of an electric motor.

[0036] Fig. 6 is a partial axial sectional view of the stator.

[0037] Fig. 7A shows a lamination in a second lamination section of the stator; Fig. 7B is a detail view of a portion of the lamination. Fig. 8A shows a lamination in a first lamination section of the stator; Fig. 8B is a detail view of a portion of the lamination.

[0038] Fig. 9A shows a lamination in an end lamination section of the stator; Fig. 9B is a detail view of a portion of the lamination.

[0039] DETAILED DESCRIPTION

[0040] To clarify the objective, technical solutions and advantages of embodiments of the present disclosure, the technical solutions of the embodiments of the present disclosure are described clearly and completely below in conjunction with the drawings of the embodiments of the present disclosure.

[0041] Unless defined otherwise, the technical or scientific terms used herein shall have the common meanings as understood by those of ordinary skill in the field to which the present disclosure belongs. Moreover, terms such as "a", "one" or "the" used in the description and claims of the patent application of the present disclosure do not indicate a quantity limit, but mean that there is at least one. Terms such as "comprise" or "include" mean that the element or object appearing before the term encompasses the elements or objects listed after the word and equivalents thereof. Terms such as "connected" or "connected together" are not restricted to a physical or mechanical connection, and may include a direct or indirect electrical connection. "Upper", "lower", "left", "right", etc. are merely used to indicate a relative positional relationship; when the absolute position of a described object changes, the relative positional relationship may also change accordingly. The terms "axial" and "axial direction" refer to the direction of the rotation axis of the electric motor.

[0042] In order to facilitate description, the drawings of the present disclosure accordingly simplify or omit components commonly used in the art, such as external connection lines and other components that are irrelevant to the description of the present disclosure. These omitted or simplified components do not affect the understanding of the content of the present disclosure by a person skilled in the art.

[0043] Fig. 1 shows an electric motor 100 in an assembled state according to an exemplary embodiment of the present disclosure; Fig. 2 shows an axial sectional view of the electric motor 100; and Fig. 3 shows an exploded view of the electric motor 100. As shown in the figures, the electric motor 100 comprises a housing 40, a rotor 10 and a stator 20 accommodated in the housing 40, and an isolating sleeve 30. The isolating sleeve 30 is installed between the rotor 10 and the stator 20, and used to isolate the rotor 10 from the stator 20. Specifically, the isolating sleeve 30 is installed at an inner ring of the stator 20, and does not come into contact with the rotor 10.

[0044] The isolating sleeve 30 isolates the rotor 10 from the stator 20, preventing cooling oil from flowing into the electric motor air gap and coming into contact with the rotor, and thereby avoiding oil agitation losses.

[0045] Referring to Fig. 4A, the isolating sleeve 30 is provided with a sealing structure 31 and an axially extending main body structure 32; the main body structure 32 extends from the sealing structure 31 to an end cover 44 at a nondriving end of the electric motor, and abuts the end cover 44. For example, the sealing structure 31 and the main body structure 32 may be integrally formed. A sealing ring 34 is also provided on the sealing structure 31, for preventing cooling oil from flowing out of the sealing structure 31.

[0046] It should be explained that the present disclosure imposes no restrictions on the shape of the main body structure 32 of the isolating sleeve 30; for example, the main body structure 32 may also be as shown in Fig. 4B. Referring to Fig. 4B, in addition to comprising an axially extending portion, the main body structure 32 also comprises an extending portion 33 that extends in a curve; this extending portion 33 extends to the end cover 44 at the non-driving end of the electric motor, and abuts the end cover 44.

[0047] Fig. 5 shows the stator 20 of the electric motor; Fig. 6 shows an axial sectional view of a portion of the stator 20. Referring to Figs. 5 and 6, the stator 20 comprises a stator core 201 and windings 202. The stator core 201 consists of multiple laminations stacked together, which may be divided into multiple lamination sections. The stator core 201 of the stator 20 is provided with circumferentially arranged stator tooth slots 28 located in the radial interior, and lugs 29 which protrude radially outwards. The windings 202 are inserted in the stator tooth slots 28, which are used for holding and separating the windings 202 of the stator 20. The windings 202 extend axially in the stator tooth slots 28 of the stator core 201, and have a winding end 203 extending beyond the stator core 201. In Fig. 6, the stator core 201 comprises an end lamination section 26, a first lamination section 24 and a second lamination section 25 in the axial direction. It will be understood that the stator core 201 also comprises a first lamination section 24 and an end lamination section 26 at the other side of the second lamination section 25 in the axial direction. The lugs 29 fit locating grooves on an inner surface of the housing 40, and are able to locate the stator core 201 of the stator 20 in the circumferential direction. Apart from the lugs 29 and the stator tooth slots 28 mentioned above, as will be described in detail below, the laminations of each lamination section of the stator 20 have the same structure, but different lamination sections may have different lamination structures.

[0048] For example, the electric motor 100 may be a drive electric motor for driving a vehicle to run, with a high alternating current circulating in the windings 202 of the drive electric motor, for the purpose of generating an alternating magnetic field for driving the rotor 10 of the electric motor to rotate about a rotation axis X of the electric motor. The stator core 201 is acted on by the alternating magnetic field, giving rise to hysteresis losses and eddy current losses. Therefore, the windings 202 and the stator core 201 of the stator 20 are the main heat generating components of the electric motor 100, and need to be cooled. For this purpose, the electric motor 100 is provided with an electric motor cooling system, which is able to cool the windings 202 and the stator core 201 of the stator 20. The electric motor cooling system may for example cool internal parts of the electric motor 100 with cooling oil.

[0049] For this purpose, the electric motor cooling system comprises an oil pump 41, an oil delivery pipe 42, a channel inside the housing 40, and an oil collector 43. Cooling oil circulating in the electric motor cooling system can be pumped by the oil pump 41 from the oil collector 43 into the housing 40 of the electric motor 100 through the oil delivery pipe 42, flow through the channel inside the housing 40 to cool the internal components of the electric motor, then collect at the bottom of the housing 40, and again flow into the oil collector 43, which is in fluid communication with the housing 40.

[0050] Specifically, the oil delivery pipe 42 runs through the housing 40, leading to an annular receiving groove 21 located in an axially middle part of the stator 20. The receiving groove 21 is formed by the second lamination section 25. Referring to Figs. 5 and 6, an external diameter of the second lamination section 25 is less than an external diameter of the first lamination section 24, such that the annular receiving groove 21 is formed under the clamping action of two first lamination sections 24. Thus, oil pumped by the oil pump 41 through the oil delivery pipe 42 is received by the stator 20 via the receiving groove 21, and can then be used to cool the stator 20.

[0051] After being received by the receiving groove 21, the oil has different flow paths on the stator 20. As shown in Fig. 6, first channels 22 in fluid communication with the receiving groove 21 are provided on the stator core 201 of the stator 20. Thus, oil received by the receiving groove 21 can flow through the first channels 22, and can be conveyed to an end of the stator 20. As shown in Fig. 6, the first channels 22 are relatively close to the radial interior of the stator core 201, i.e. close to the stator tooth slots 28 of the stator core 201. The first channels 22 are arranged on a lamination section other than the second lamination section 25 forming the receiving groove 21.

[0052] Referring to Figs. 8 A and 8B, the laminations in the first lamination section 24 are provided with lamination holes 241, and these lamination holes 241 form portions of the first channels 22 in the first lamination section 24. In particular, the lamination hole 241 is composed of an external section 241a and an obround internal section 241b. The external section 241a of the lamination hole 241 is connected to the receiving groove 21 via a radially outside portion of the external section, enabling oil to flow into the lamination hole 241. The internal section 241b of the lamination hole 241, in particular a radially inside portion thereof, is close to the stator tooth slots 28, and can thus cool the windings 202 in the stator tooth slots 28. Referring to Figs. 9A and 9B, the laminations in the end lamination section 26 are provided with obround end holes 261. These end holes 261 are aligned with the radially inside portions of the lamination holes 241 in the axial direction, forming portions of the first channels 22 in the end lamination section 26. Oil flowing in the lamination holes 241 can be sprayed through the end holes 261 onto the winding end 203 of the windings 202, to cool the winding end 203. The area of the end holes 261 is greatly reduced relative to the lamination holes 241, helping to increase the flow speed at which oil is sprayed out of the end holes 261, and increasing the proportion of oil sprayed onto the winding end 203.

[0053] The lamination holes 241 and the end holes 261 described above are all arranged in a yoke of the laminations of the stator core 201, i.e. a top region close to the windings 202 in the stator tooth slots 28. This region is a region where heating is severe, and the present disclosure is able to cool the yoke of the stator directly with cooling oil.

[0054] Referring to Fig. 2, the isolating sleeve 30 is provided with the sealing structure 31 at a driving end of the electric motor, and the sealing structure 31 can enclose the winding end 203. Thus, after cooling oil has cooled the winding end 203, this cooling oil is blocked by the sealing structure 31 and thus prevented from flowing out of gaps in the winding end 203, and so fully infiltrates the winding end 203, and then flows from the driving end of the electric motor to the non-driving end of the electric motor due to a pressure difference. The isolating sleeve 30 extends to the end cover 44 at the non-driving end of the electric motor. After the cooling oil has flowed to the non-driving end of the electric motor and cooled the winding end 203 at the non-driving end, the oil collects at the bottom of the housing 40 and flows into the oil collector 43 through an oil outlet on the housing 40. Referring to Figs. 7A - 9B, harmonic holes 281 are also provided between the stator tooth slots 28 on the laminations of the stator core 201. To prevent cooling oil from leaking out at openings of the harmonic holes 281 and the stator tooth slots 28 and flowing radially to the rotor part, the isolating sleeve 30 is fitted to an inner wall of the stator core 201 to isolate the rotor 20 from the stator 10, thereby ensuring that the cooling oil can only flow axially. When flowing from the driving end of the electric motor to the non-driving end of the electric motor, the cooling oil passes through the stator tooth slots 28 on the stator core 201 to directly cool the windings 202 in the stator tooth slots 28, and passes through the harmonic holes 281 on the stator core 201, thereby carrying away heat more quickly.

[0055] In addition to the first channels 22, the stator 20 is also provided with second channels 23, which are in fluid communication with the receiving groove 21 so as to convey oil from the receiving groove 21 to the non-driving end of the electric motor. Referring to Figs. 8A - 9B, bolt holes 27 for fasteners to pass through are arranged on the first lamination sections 24 and the end lamination sections 26 at the positions of the lugs 29; bolt holes 27 (see Fig. 4A) are correspondingly arranged on the sealing structure 31 of the isolating sleeve 30, and the first lamination section 24 and end lamination section 26 close to the driving end of the electric motor are fixed to the isolating sleeve 30 by means of the fasteners. The bolt holes 27 of the first lamination section 24 and end lamination section 26 close to the non-driving end of the electric motor are in communication with the receiving groove 21, so that oil can flow into the bolt holes 27, and the oil flowing in the bolt holes 27 can be sprayed onto the winding end 203 of the windings 202 to cool the winding end 203. After cooling the winding end 203, the oil collects at the bottom of the housing 40 and flows into the oil collector 43. At the bottom of the housing 40 and in the oil collector 43, the oil that flows through the first channels 22 mixes fully with the oil that flows through the second channels 23.

[0056] Fig. 2 shows the isolating sleeve shown in Fig. 4A; in this embodiment, the winding ends 203 at the driving end and the non-driving end of the electric motor are both fully infiltrated and cooled. If the isolating sleeve shown in Fig. 4B is used, only the winding end 203 at the driving end of the electric motor will be fully infiltrated and cooled.

[0057] According to another aspect of the present disclosure, an electric drive assembly system is proposed, comprising the electric motor as described above. It should be understood that the electric drive assembly system of the present disclosure also has the advantages described above in relation to the electric motor cooling system. According to another aspect of the present disclosure, a vehicle is proposed, comprising the electric drive assembly system as described above. The vehicle may be an electrified vehicle, such as a battery electric vehicle (BEV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), a range extended EV or a fuel cell electric vehicle (FCEV). The vehicle may also be a hydrogen-powered vehicle. It should be understood that the vehicle of the present disclosure also has the advantages described above in relation to the electric motor cooling system.

[0058] Certain features, structures or characteristics in one or more embodiments of the present disclosure may be combined appropriately.

[0059] The above is a description of the present disclosure and should not be regarded as a limitation thereof. Although some exemplary embodiments of the present disclosure have been described, those skilled in the art will readily understand that many modifications could be made to the exemplary embodiments without departing from the original teaching and advantages of the present disclosure. Therefore, all such modifications are intended to be included in the scope of the present disclosure as defined by the claims. It should be understood that the above is an explanation of the present disclosure and the present disclosure should not be considered to be limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments and other embodiments are intended to be included within the scope of the present disclosure.

Claims

WHAT IS CLAIMED IS:

1. An electric motor cooling system, characterized in that the electric motor cooling system comprises a rotor (10) and a stator (20), wherein the stator (20) comprises a stator core (201) and a winding (202), and the stator core (201) is provided with an annular receiving groove (21) at an outer periphery thereof, for the purpose of receiving oil supplied from an oil pump (41), and the stator (20) is provided with a first channel (22) for conveying the oil from the receiving groove (21) to two ends of the stator (20), wherein the electric motor cooling system further comprises an isolating sleeve (30) for isolating the rotor (10) from the stator (20), wherein the isolating sleeve (30) is provided with a sealing structure (31) at a driving end of the electric motor, causing the oil to be conveyed from the driving end of the electric motor to a non-driving end of the electric motor.

2. The electric motor cooling system according to Claim 1, characterized in that the isolating sleeve (30) further comprises an axially extending main body structure (32), and the main body structure (32) extends from the sealing structure (31) to an end cover (44) at the non-driving end of the electric motor.

3. The electric motor cooling system according to Claim 1 , characterized in that the first channels (22) are distributed at intervals circumferentially and in fluid communication with the receiving groove (21).

4. The electric motor cooling system according to Claim 1, characterized in that the stator core (201) comprises two axially arranged first lamination sections (24) and a second lamination section (25) arranged between the two first lamination sections.

5. The electric motor cooling system according to Claim 4, characterized in that the receiving groove (21) is arranged on the second lamination section (25).

6. The electric motor cooling system according to Claim 4, characterized in that at least a portion of the first channel (22) is arranged on the first lamination section (24).

7. The electric motor cooling system according to Claim 4, characterized inthat the stator core (201) further comprises an end lamination section (26) arranged on a side, axially opposite the second lamination section (25), of each of the two first lamination sections (24), at least a portion of the first channel (22) being arranged on the end lamination section (26).

8. The electric motor cooling system according to Claim 7, characterized in that bolt holes (27) for fasteners to pass through are arranged circumferentially on the first lamination section (24) and the end lamination section (26).

9. The electric motor cooling system according to Claim 8, characterized in that bolt holes (27) are correspondingly arranged on the sealing structure (31) of the isolating sleeve (30), and the first lamination section (24) and end lamination section (26) close to the driving end of the electric motor are fixed to the isolating sleeve (30) by the fasteners.

10. The electric motor cooling system according to Claim 8, characterized in that the stator is further provided with a second channel (23) for conveying the oil from the receiving groove (21) to the non-driving end of the electric motor, and at least a portion of the second channel (23) runs through the bolt hole (27).

11. The electric motor cooling system according to Claim 1 , characterized in that stator tooth slots (28) are arranged circumferentially on the stator core (201), and the winding (202) is inserted in the stator tooth slots (28), and the oil flows from the driving end of the electric motor towards the non-driving end of the electric motor through the stator tooth slots (28) of the stator core.

12. The electric motor cooling system according to Claim 1, characterized in that the electric motor cooling system further comprises a housing (40), and the oil flows into an oil collector (43) through an oil outlet on the housing (40).

13. An electric motor (100), comprising the electric motor cooling system according to any one of Claims 1 - 12.

14. An electric drive assembly system, comprising the electric motor (100) according to Claim 13.

15. A vehicle, comprising the electric drive assembly system according to Claim 14.

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