Rotor, electric motor, electric drive system and vehicle

Abstract

The present disclosure relates to a rotor of an electric motor, comprising a rotor lamination assembly; a motor shaft capable of rotating around a rotation axis and rotatably fixed to the rotor lamination assembly, the motor shaft comprising a first end and a second end that extend beyond the rotor lamination assembly, the second end being opposite to the first end; and a fastening assembly fixed to the motor shaft at at least one of the first and second ends and pressed against the rotor lamination assembly. The motor shaft comprises a central hole and a first communicating hole in communication with the central hole, the fastening assembly comprises a second communicating hole in communication with an outer surface of the fastening assembly, and an accommodating space for a cooling fluid is provided in an interface area between the motor shaft and the fastening assembly.

Description

[0001] ROTOR, ELECTRIC MOTOR, ELECTRIC DRIVE SYSTEM AND VEHICLE

[0002] TECHNICAL FIELD

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

[0004] BACKGROUND

[0005] The electric motors used to drive vehicles usually have greater 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. Oil-cooled electric motors can bring a cooling medium (cooling fluid) into direct contact with the internal components of the electric motor, and so have a better cooling effect and are used increasingly extensively in the field of vehicles. Cooling fluid is usually introduced to an oil- cooled electric motor at the electric motor shaft of the rotor, and a centrifugal force generated when the rotor rotates causes the cooling fluid to be sprayed radially outwards to cool various components of the electric motor.

[0006] The windings of the stator are a major heat-generating component of the electric motor and generally include ends extending beyond the stator main body at both axial ends of the electric motor. Therefore, it is desired that the cooling fluid entering the rotor can be sprayed directly to the windings of the stator at both axial ends of the electric motor to cool the windings.

[0007] A rotor of an electric motor typically comprises a plurality of plates tightly stacked together, which are secured by fasteners arranged at axial ends thereof so that the plates remain tightly stacked even when the electric motor rotates at high speeds. The fasteners hinder the spraying of a cooling fluid from the motor shaft of the rotor towards the winding end of the stator. The fasteners are avoided usually by spraying the cooling fluid from the outer axial side of the fasteners towards the i winding end.

[0008] However, to increase the power density of the electric motor, the axial length of the winding extending beyond the stator body is compressed, which means that the winding end is shortened. As a result, the cooling fluid sprayed on the axial outer side of the fastener only reaches the very end of the winding end, or even completely fails to be sprayed on the winding end, so the cooling effect of the electric motor is reduced.

[0009] SUMMARY OF THE INVENTION

[0010] In view of the above, the present disclosure is intended to solve the above- mentioned problems in conventional rotor of an electric motor , and an objective thereof is to provide a rotor that can spray cooling fluid at a position close to the rotor laminations in the axial direction, so that even if the winding end is shortened, the cooling fluid can be reliably sprayed onto the winding end to fully cool the stator winding of the electric motor.

[0011] The objective is achieved by a rotor of an electric motor according to an embodiment of the present disclosure, the rotor comprising a rotor lamination assembly; a motor shaft capable of rotating around a rotation axis and rotatably fixed to the rotor lamination assembly, the motor shaft comprising a first end and a second end that extend beyond the rotor lamination assembly, the second end being opposite to the first end; and a fastening assembly fixed to the motor shaft at at least one of the first end and the second end, and pressed against the rotor lamination assembly. The motor shaft comprises a central hole and a first communicating hole in communication with the central hole, the fastening assembly comprises a second communicating hole in communication with the outer surface of the fastening assembly, and an accommodating space for a cooling fluid is provided in an interface area between the motor shaft and the fastening assembly and is in communication with the first and second communicating holes.

[0012] An objective of the present disclosure is to provide a rotor that can spray cooling fluid at a position close to the rotor laminations in the axial direction. A rotor according to the present disclosure comprises a central hole provided on the motor shaft, a first communicating hole in communication with the central hole, an accommodating space provided in an interface area between the motor shaft and the fastening assembly, and a second communicating hole provided on the fastening assembly and in communication with the outer surface of the fastening assembly. Thus, the cooling fluid can pass through the fastening assembly from the central hole of the motor shaft through the first communicating hole, the accommodating space, and the second communicating hole, and is sprayed towards the winding end of the stator under the action of centrifugal force. In other words, the rotor can spray the cooling fluid through the fastening assembly, thereby spraying the cooling fluid at a position close to the rotor laminations in the axial direction. Thus, even if the winding end is shortened, the rotor can reliably spray the cooling fluid onto the winding end to fully cool the stator winding of the electric motor.

[0013] The rotor according to the present disclosure may also have one or more of the following features, alone or in combination.

[0014] According to one embodiment of the present disclosure, the accommodating space is a groove. The groove is, for example, a circumferential groove. Preferably, the circumferential groove encircles the entire circumference of the interface area.

[0015] According to one embodiment of the present disclosure, the groove is provided on the outer surface of the motor shaft; alternatively, the groove is provided on the inner surface of the fastening assembly.

[0016] According to one embodiment of the present disclosure, the groove comprises a first groove portion provided on the outer surface of the motor shaft and a second groove portion provided on the inner surface of the fastening assembly. For example, the groove is formed by the cooperation of the first and second groove portions that are aligned with each other.

[0017] According to one embodiment of the present disclosure, the fastening assembly comprises a nut screwed onto the motor shaft.

[0018] According to one embodiment of the present disclosure, the nut comprises a first section provided with threads and a second section closer to the rotor lamination assembly, wherein the groove is provided in an interface area between the second section and the motor shaft.

[0019] According to one embodiment of the present disclosure, the fastening assembly comprises a gasket arranged between the nut and the rotor lamination assembly.

[0020] According to one embodiment of the present disclosure, the fastening assembly comprises an end plate arranged between the gasket and the rotor lamination assembly.

[0021] According to one embodiment of the present disclosure, the groove is provided in an interface area between the gasket or the end plate and the motor shaft.

[0022] According to one embodiment of the present disclosure, the motor shaft comprises a plurality of first communicating holes uniformly distributed around the rotation axis, and / or the fastening assembly comprises a plurality of second communicating holes uniformly distributed around the rotation axis.

[0023] The present disclosure further relates to an electric motor comprising a rotor as described above.

[0024] The present disclosure further relates to an electric drive system comprising an electric motor as described above.

[0025] The present disclosure further relates to a vehicle comprising the electric drive system as described above.

[0026] BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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 scaled drawings according to actual dimensions but rather focus on showing the main purpose of the present disclosure.

[0028] Fig. 1 is a side view of the rotor of an electric motor according to the present disclosure. Fig. 2 is a schematic sectional view of the electric motor according to the present disclosure.

[0029] Fig. 3 is the motor shaft of the rotor according to the present disclosure.

[0030] Fig. 4 is the nut of the rotor according to the present disclosure.

[0031] DESCRIPTION OF THE EMBODIMENTS

[0032] 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.

[0033] 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. “One”, “a” or “said” and similar words 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. “Comprise” or “include” and similar words mean that the element or object appearing before the word encompasses the elements or objects and their equivalents listed after the word. “Connected” or “coupled” and similar words are not limited to a physical or mechanical connection, and may include an electrical connection, whether direct or indirect. “Upper”, “lower”, “left”, “right”, etc., are only used to indicate a relative positional relationship, and when the absolute position of the described object changes, the relative positional relationship might also change accordingly. The terms “axial” and “axial direction” refer to the direction of the rotation axis X of the rotor, “radial” and “radial direction” refer to the direction perpendicular to the rotation axis X, and “circumferential” and “circumferential direction” refer to the circumferential direction around the rotation axis X.

[0034] 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.

[0035] Fig. 1 shows a rotor 100 of an electric motor according to an exemplary embodiment of the present disclosure. Fig. 2 is a sectional view of an electric motor comprising the rotor 100.

[0036] As shown in Fig. 1 and Fig. 2, the electric motor comprises a rotor 100 and a motor stator 200. The rotor 100 comprises a rotor lamination assembly 10 and a motor shaft 20. The motor shaft 20 passes through the axis of the rotor lamination assembly 10 and is rotatably fixed to the rotor lamination assembly 10, which rotate together around the rotation axis X. The motor shaft 20 comprises a first end 20a extending beyond the rotor lamination assembly 20 and a second end 20b opposite the first end 20a.

[0037] The rotor lamination assembly 20 is formed by a set of stacked rotor laminations. These rotor laminations are tightly stacked together with sufficient compression force to ensure the stiffness and strength of the rotor. To ensure that the rotor laminations are tightly held when the rotor rotates at high speeds, the rotor 1 further comprises a fastening assembly 30, which is fixed to the motor shaft 20 at the first end 20a and / or the second end 20b of the motor shaft 20 and pressed against the rotor lamination assembly 10. As shown in Fig. 1, the fastening assembly 30 at the second end 20b comprises an end plate 33 positioned close to the rotor lamination assembly 10, a nut 31 screwed onto the motor shaft 20, and a gasket 32 arranged between the end plate 33 and the nut 31. The nut 31 is pressed against the end plate 33 towards the rotor lamination assembly 10 through the gasket 32, applying a compressive force to tightly stack the rotor laminations together. It should be understood that some components in the fastening assembly 30, such as the end plate 33 and the gasket 32, can be omitted.

[0038] A cooling fluid circulates inside the electric motor to cool various components of the electric motor 100. For example, the cooling fluid may be cooling oil. Referring to Fig. 2, the motor shaft 20 can be provided with a central hole 21. The cooling fluid flows into the motor shaft 20 from the central hole 21, and then, driven by a centrifugal force, is sprayed radially from the motor shaft 20 to reach the various components of the electric motor 100, thereby cooling the electric motor.

[0039] Among the various components of the electric motor 100, the stator 200 comprises a winding in which a relatively large alternating current flows, for generating an alternating magnetic field that drives the rotor 100 to rotate. Therefore, the winding of the stator 200 is one of the main heat-generating components of the electric motor 100. As shown in Fig. 2, the winding extends beyond the main body 201 of the stator 200, forming the winding end 202. For the cooling of the stator 200, preferably the cooling fluid is sprayed directly radially onto the winding end 202, and then flows axially to cool the entire stator 200.

[0040] However, as shown in Fig. 2, the rotor lamination assembly 10 of the rotor 100 substantially overlaps with the main body 201 of the stator 200 in the radial direction, and the winding end 202 substantially overlaps with the fastening assembly 30 in the radial direction. Specifically, in the case where the axial length of the winding end 202 is small (as shown in Fig. 2), if the rotor 100 sprays a cooling fluid radially on the axial outer side of the fastening assembly 30 (namely the side away from the rotor lamination assembly 10), it will be difficult for the cooling fluid to be sprayed onto the winding end 202. Therefore, the rotor 100 needs to pass through the fastening assembly 30 to be exposed to sprinkles of the cooling fluid in order to ensure that the cooling fluid is reliably sprayed onto the winding end 202. Therefore, the rotor 100 according to the present disclosure is provided with a passage for the cooling fluid to pass through the fastening assembly 30.

[0041] Referring to Figs. 1-2, at the second end 20b of the motor shaft 20, an accommodating space for cooling fluid is provided in an interface area between the motor shaft 20 and the fastening assembly 30 and has the form of a groove 1, for example. Preferably, the groove 1 is a circumferential groove encircling the interface area. The motor shaft 20 is provided with a first communicating hole 22 that is in fluid communication with the central hole 21 and the groove 1 , and the fastening assembly 30 is provided with a second communicating hole 34 that is in fluid communication with the groove 1 and the outer surface thereof. The cooling fluid supplied from the central hole 21 to the motor shaft 20 can be reliably sprayed onto the winding end 202 through the first communicating hole 22, the groove 1, and the second communicating hole 34. The second communicating hole 34, the groove 1 , and the first communicating hole 22 form a passage for a cooling fluid to pass through the fastening assembly 30. With the above structure, the cooling fluid in the central hole 21 enters the groove 1 through the first communicating hole 22, then flows into the second communicating hole 34, and is sprayed from the second communicating hole 34 towards the winding end 202 to cool it. In other words, the flow path of the cooling fluid in the rotor 100 according to this embodiment is: central hole 21 — first communicating hole 22 groove 1 second communicating hole 34.

[0042] Referring to Figs. 2-4, the groove 1 is provided on the outer surface of motor shaft 20 and is a circumferential groove that is inwardly recessed on the outer surface of the motor shaft 20. The axial position of the first communicating hole 22 is substantially the same as that of the groove 1 , and the first communicating hole 22 extends radially to be in communication with the central hole 21 and the groove 1. The nut 31 comprises a first section 3 la with threads and a second section 3 lb closer to the rotor lamination assembly 10. The corresponding part of the motor shaft 20 is also provided with corresponding threads, so that the nut 31 can be screwed onto the motor shaft 20 by the first section 31a. The axial position of the second section 31b corresponds to the groove 1, that is, the groove 1 is provided in an interface area between the second section 31b and the motor shaft 20. Correspondingly, the second communicating hole 34 is also provided on the second section 31b of the nut 31, and the second communicating hole 34 has an axial position substantially the same as that of the groove 1 , extending radially to the outer surface of the nut 31. The nut 31 may also be provided with a fixing groove 35 on its outer surface, the fixing groove 35 being capable of cooperating with a tool to tighten the nut 31. In the embodiment shown in Fig. 4, the second communicating hole 34 leads to the bottom surface of the fixing groove 35.

[0043] In an optional embodiment not shown in the drawings, the groove 1 may also be provided on the inner surface of the fastening assembly 30 and is a circumferential groove recessed outwards from the inner surface of the fastening assembly 30. Further, optionally, the groove 1 can be partially provided on the motor shaft 20 and partially provided on the fastening assembly 30. In other words, the groove 1 can be composed of a first groove portion provided on the outer surface of motor shaft 20 and a second groove portion provided on the inner surface of fastening assembly 30. In the axial direction, the groove 1 can be closer to the rotor lamination assembly 10, that is, the groove 1 can be provided in an interface area between the gasket 32 or end plate 33 and the motor shaft 20. Correspondingly, the second communicating hole 34 may also be provided on the gasket 32 or on the end plate 33.

[0044] In addition, Fig. 2 shows that the first communicating hole 22 is aligned with the second communicating hole 34. Since the groove 1 is provided in an interface area between the motor shaft 20 and the fastening assembly 30, the first communicating hole 22 and the second communicating hole 34 may also be staggered. The cooling fluid can flow in the circumferential direction in the groove 1 at a certain angle before entering the second communicating hole 34. Therefore, for the installation of the fastening assembly 30, it is no longer necessary to align the first communicating hole 22 and the second communicating hole 34, which reduces the difficulty of assembling the rotor 100. Indeed, the first communicating hole 22 and the second communicating hole 34 may also be staggered at a predetermined angle to adjust the flow resistance met by the sprayed cooling fluid. The motor shaft 20 comprises a plurality of first communicating holes 22 (whose quantity is 4 as shown in the drawing) uniformly distributed around the rotation axis X, and the fastening assembly 30 also comprises a plurality of second communicating holes 34 (whose quantity is 4 as shown in the drawing) uniformly distributed around the rotation axis X, wherein the quantities of the two can be the same or different. The groove 1 can be a single groove that completely surrounds the interface area, or it can be composed of a plurality of segmented grooves, each of which can be in communication with a first communicating hole 22 and a second communicating hole 34. In addition, the first communicating hole 22 and the second communicating hole 34 can also extend at a certain angle to the radial direction. The configuration of the second end 20b of the motor shaft 20 and that of the fastening assembly 30 located at the second end 20b of the motor shaft 20 have been described above in conjunction with the drawings. As shown in Figs. 1-3, the rotor 100 has different configurations at the first end 20a of the motor shaft 20. Specifically, the motor shaft 20 is provided with a flange 23 at the first end 20a, and the end plate 33 is arranged between the flange 23 and the rotor lamination assembly 10. The flange 23 forms a stopper for the end plate 33 at the first end 20a, so that the rotor lamination assembly 10 is compressed between the two end plates 33 at the first end 20a and the second end 20b. A radial hole 24 in communication with the central hole 21 is provided on the flange 23 to allow direct spraying of the cooling fluid onto the winding end 202. It can be understood that the configuration of the rotor 100 at the first end 20a of the motor shaft 20 may also be the same as its configuration at the second end 20b. In other words, the fastening assembly 30 may also be arranged at the first end 20a of the motor shaft 20.

[0045] According to another aspect of the present disclosure, an electric drive system is proposed, comprising the electric motor as described above.

[0046] According to another aspect of the present disclosure, a vehicle is provided, comprising an electric drive 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 and a fuel cell electric vehicle (FCEV). The vehicle may also be a hydrogen-powered vehicle.

[0047] Certain features, structures or characteristics in one or more embodiments of the present disclosure may be combined appropriately.

[0048] The above is a description of the present disclosure and should not be regarded as limiting it. Although a number of exemplary embodiments of the present disclosure have been described, those skilled in the art will readily understand that many modifications may be made to the exemplary embodiments without departing from the novel 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 a description of the present disclosure; the present disclosure should not be considered to be limited to the specific embodiments disclosed, and 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. A rotor (100) of an electric motor, comprising: a rotor lamination assembly (10); a motor shaft (20) capable of rotating around a rotation axis (X) and rotatably fixed to the rotor lamination assembly (20), and comprising a first end (20a) and a second end (20b) that extend beyond the rotor lamination assembly (20), and the second end (20b) being opposite to the first end (20a), and a fastening assembly (30) fixed to the motor shaft (20) at at least one of the first end (20a) and the second end (20b), and pressed against the rotor lamination assembly (10), wherein the motor shaft (20) comprises a central hole (21) and a first communicating hole (22) in communication with the central hole (21), and the fastening assembly (30) comprises a second communicating hole (34) in communication with an outer surface of the fastening assembly (30), and an accommodating space for a cooling fluid is provided in an interface area between the motor shaft (20) and the fastening assembly (30) and is in communication with the first communicating hole (22) and the second communicating hole (34).

2. The rotor (100) according to claim 1, wherein the accommodating space is a groove (1).

3. The rotor (100) according to claim 2, wherein the groove (1) is arranged on an outer surface of the motor shaft (20); or the groove (1) is provided on an inner surface of the fastening assembly (30).

4. The rotor (100) according to claim 2, wherein the groove (1) comprises a first groove portion provided on the outer surface of the motor shaft (20) and a second groove portion provided on an inner surface of the fastening assembly (30).

5. The rotor (100) according to any one of claims 1 to 4, wherein the fastening assembly (30) comprises a nut (31) screwed onto the motor shaft6. The rotor (100) according to claim 5, wherein the nut (31) comprises a first section (31a) with threads and a second section (31b) closer to the rotor lamination assembly (10), the groove (1) being provided in an interface area between the second section (31b) and the motor shaft (20).

7. The rotor (100) according to claim 5, wherein the fastening assembly (30) comprises a gasket (32) arranged between the nut (31) and the rotor lamination assembly (10).

8. The rotor (100) according to claim 7, wherein the fastening assembly (30) comprises an end plate (33) arranged between the gasket (32) and the rotor lamination assembly (10).

9. The rotor (100) according to claim 8, wherein the groove (1) is arranged in an interface area between the gasket (32) or the end plate (33) and the motor shaft (20).

10. The rotor (100) according to any one of claims 1 to 4, wherein the motor shaft (20) comprises a plurality of first communicating holes (22) uniformly distributed around the rotation axis (X), and / or the fastening assembly (30) comprises a plurality of second communicating holes (34) uniformly distributed around the rotation axis (X).

11. An electric motor, comprising a rotor (100) according to any one of claims 1 to 10.

12. An electric drive system, comprising at least an electric motor according to claim 11.

13. A vehicle, comprising an electric drive system according to claim 12.

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