Electric motor rotor, electric motor, electric drive apparatus and vehicle

Abstract

The present disclosure relates to an electric motor rotor, which includes: an electric motor shaft, which is capable of rotating around a rotation axis X, and includes a central hole and a communicating hole that communicates with the central hole; a rotor core, which is fitted around and rotatably fixed to the electric motor shaft, the rotor core including two end plates and a lamination assembly that is arranged between the two end plates. The rotor core is internally provided with at least one cooling channel for a cooling medium to flow in, this cooling channel including: an inlet section that communicates with the communicating hole; an outlet section that is arranged in one of the two end plates; a turned back section that is arranged in the other of the two end plates; a front circulation section by which the inlet section communicates with the turned back section; and a back circulation section by which the turned back section communicates with the outlet section. The present disclosure further relates to an electric motor including such an electric motor rotor, an electric drive apparatus including such an electric motor, and a vehicle including such an electric drive apparatus.

Description

[0001] Description

[0002] Electric motor rotor, electric motor, electric drive apparatus and vehicle

[0003] Technical Field

[0004] The present disclosure relates to an electric motor rotor. The present disclosure further relates to an electric motor comprising such an electric motor rotor, an electric drive apparatus comprising the electric motor, and a vehicle comprising the electric drive apparatus.

[0005] Background Art

[0006] 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, affecting the reliability and performance of the electric motor. For example, an electric motor rotor generally comprises multiple rotor magnets that are arranged inside the rotor core. An excessively high temperature can cause the magnets to demagnetize, reducing reliability of the electric motor.

[0007] 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. A cooling medium generally passes into an oil-cooled electric motor at an electric motor shaft of an electric motor rotor, and passes through cooling channels inside laminations of the rotor to cool rotor magnets and other components of the electric motor. However, the distribution of the cooling medium in the cooling channels is often not even, affecting the balance of the rotor, and causing a temperature difference inside the rotor.

[0008] Summary of the Invention

[0009] Therefore, the present disclosure is intended to solve the above problem i present in conventional electric motor rotors, the object thereof being to provide an electric motor rotor, wherein a cooling channel that is arranged in a rotor core enables cooling medium to be evenly distributed in the cooling channel and fully cool the electric motor rotor evenly.

[0010] The object is realised by means of an electric motor rotor according to an embodiment of the present disclosure, which comprises: an electric motor shaft, which is able to rotate around a rotation axis X, and comprises a central hole and a communicating hole that communicates with the central hole; a rotor core, which is fitted around and rotatably fixed to the electric motor shaft, the rotor core comprising two end plates and a lamination assembly that is arranged between the two end plates. The rotor core is internally provided with at least one cooling channel for a cooling medium to flow in, this cooling channel comprising: an inlet section that communicates with the communicating hole; an outlet section that is arranged in one of the two end plates; a turned back section that is arranged in the other of the two end plates; a front circulation section by which the inlet section communicates with the turned back section; and a back circulation section by which the turned back section communicates with the outlet section.

[0011] One of the objects of the present disclosure is to provide an electric motor rotor, wherein cooling medium is evenly distributed in a cooling channel of a rotor core, to fully cool the electric motor rotor evenly. The rotor core of the electric motor rotor according to the present disclosure comprises two end plates and a lamination assembly that is arranged between the two end plates, and the cooling channel that is arranged in the rotor core comprises an inlet section, an outlet section, a turned back section, a front circulation section and a back circulation section. Cooling medium flows from the central hole of the electric motor shaft into the inlet section of the cooling channel via the communicating hole, flows to the turned back section on one end plate via the front circulation section, and flows to the outlet section located on the other end plate from the turned back section via the back circulation section, and flows out from the outlet section to the cooling channel. By means of the above turned back section, the cooling medium has opposite flowing directions in the front circulation section and the back circulation section. The multiple sections of the cooling channel enable the cooling medium to be distributed evenly in the rotor core, and fully cool the electric motor rotor evenly.

[0012] The motor rotor according to the present disclosure may also have one or more of the following features, alone or in combination.

[0013] According to an optional embodiment of the present disclosure, the communicating hole is located at an axial middle position of the electric motor shaft. That is, cooling medium enters the cooling channel from an axial middle position of the electric motor shaft, and flows toward two sides. Compared to a conventional construction in which a cooling medium enters a cooling channel from one side, the arrangement of the cooling channel according to the present disclosure has better axial symmetry, and further increases the uniformity of distribution of the cooling medium in the electric motor rotor.

[0014] According to an optional embodiment of the present disclosure, the turned back section of the cooling channel is a turned back recess that is formed in the other end plate of the two end plates, wherein the turned back recess comprises a receiving part that communicates with the front circulation section, a return part that communicates with the back circulation section, and a turned back channel by which the receiving part communicates with the return part. Due to the above construction thereof, the turned back section is suited to communicate with the front circulation section and the back circulation section, and realises a function of reversing the flowing direction of the cooling medium.

[0015] According to an optional embodiment of the present disclosure, the return part is located at a radial outer side of the receiving part. Consequently, the back circulation section that communicates with the return part may also be located on a radial outer side of the front circulation section that communicates with the receiving part. The front circulation section and the back circulation section are located at different radial positions, allowing cooling of different radial portions of the rotor core.

[0016] According to an optional embodiment of the present disclosure, the return part has a V shape, and the turned back channel is connected to the return part at the top of the V shape.

[0017] According to an optional embodiment of the present disclosure, the outlet section of the cooling channel is an outlet recess that is formed on said one end plate of the two end plates, and the outlet recess is open toward the outside of the electric motor rotor. Cooling medium sprays outward from this outlet recess, and can be used for cooling other portions of the rotor.

[0018] According to an optional embodiment of the present disclosure, the outlet slot is open on a radial edge of said one end plate. Thus, cooling medium that flows out from the outlet recess is sprayed onto a radial outer side of the electric motor rotor, to cool other portions of the electric motor. For example, cooling medium can be sprayed onto a winding end of an electric motor stator that is located at a radial outer side of the electric motor rotor, for the purpose of cooling the winding of the electric motor stator.

[0019] According to an optional embodiment of the present disclosure, the lamination assembly comprises a middle lamination, a first stress elimination hole and a fluid inlet that connects the first stress elimination hole to the communicating hole being provided on the middle lamination, and the first stress elimination hole and the fluid inlet forming the inlet section of the cooling channel.

[0020] According to an optional embodiment of the present disclosure, the lamination assembly further comprises a side lamination that is arranged at two sides of the middle lamination, a second stress elimination hole being provided on the side lamination, the second stress elimination hole being at least partially aligned with the first stress elimination hole, and the second stress elimination hole forming the front circulation section of the cooling channel.

[0021] According to an optional embodiment of the present disclosure, the middle lamination and the side lamination are further provided with a mounting hole for mounting a rotor magnet, the mounting holes of the middle lamination and the side lamination being at least partially aligned with each other, forming the back circulation section of the cooling channel. The cooling medium that flows in the back circulation section can directly contact and cool the rotor magnet.

[0022] According to the above technical features, with just two types of laminations, namely the middle lamination and the side lamination, a lamination assembly comprising the abovementioned cooling channel can be formed, reducing the types of laminations of the lamination assembly.

[0023] According to an optional embodiment of the present disclosure, the back circulation section of the cooling channel comprises two branches formed by two mounting holes, and the outlet section of the cooling channel comprises two branches that are formed by the two outlet recesses. The branch construction of the cooling channel is advantageous for the even distribution of cooling medium in the rotor core.

[0024] According to an optional embodiment of the present disclosure, the rotor core is internally provided with multiple cooling channels that are distributed circumferentially, and turned back recesses and outlet recesses of the multiple cooling channels are circumferentially staggered on the same end plate. Such a construction is further advantageous for the even distribution of the cooling medium in the rotor core.

[0025] According to an optional embodiment of the present disclosure, the cooling channel that is arranged in the rotor core comprises a first cooling channel and a second cooling channel, the first cooling channel and the second cooling channel having a shared inlet section, and the first cooling channel further comprises a first front circulation section, a first turned back section, a first back circulation section and a first outlet section; the second cooling channel further comprises a second front circulation section, a second turned back section, a second back circulation section and a second outlet section.

[0026] According to an optional embodiment of the present disclosure, the first front circulation section and the second front circulation section extend in opposite axial directions, the first back circulation section and the second back circulation section being located at different radial positions, the first turned back section and the second outlet section being arranged on one end plate, and the first outlet section and the second turned back section being arranged on the other end plate.

[0027] According to an optional embodiment of the present disclosure, the turned back recess comprises a first turned back recess that forms the first turned back section and a second turned back recess that forms the second turned back section, the mounting hole comprises a first mounting hole that forms the first back circulation section and a second mounting hole that forms the second back circulation section, the outlet recess comprises a first outlet recess that forms the first outlet section and a second outlet recess that forms the second outlet section.

[0028] According to an optional embodiment of the present disclosure, the first turned back recess and the second outlet recess radially overlap on the same end plate, and the first outlet recess and the second turned back recess radially overlap on the same end plate.

[0029] According to an optional embodiment of the present disclosure, two end plates of the rotor core are rotated by 3607n relative to each other, wherein n is a number of communicating holes that are arranged on the electric motor shaft.

[0030] The present disclosure further relates to an electric motor, which comprises the electric motor rotor as described above.

[0031] The present disclosure further relates to an electric drive apparatus, which comprises the electric motor as described above.

[0032] The present disclosure further relates to a vehicle, comprising the electric drive unit described above.

[0033] Brief Description of the Drawings

[0034] 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. In the figures:

[0035] Fig. 1 is a perspective view of an electric motor rotor according to an embodiment of the present disclosure.

[0036] Fig. 2 schematically shows a cooling channel of an electric motor rotor.

[0037] Fig. 3 shows an end plate of a rotor core of an electric motor rotor according to an embodiment of the present disclosure.

[0038] Fig. 4 shows an enlarged portion of the end plate shown in Fig. 3.

[0039] Fig. 5 shows a middle lamination of a rotor core of an electric motor rotor according to an embodiment of the present disclosure.

[0040] Fig. 6 shows a side lamination of a rotor core of an electric motor rotor according to an embodiment of the present disclosure.

[0041] Fig. 7 and Fig. 8 schematically show two cooling channels at adjacent circumferential positions.

[0042] Fig. 9 shows an electric motor shaft of an electric motor rotor according to an embodiment of the present disclosure.

[0043] In the drawings, identical or similar components are indicated by identical reference numerals.

[0044] Detailed Description of Embodiments

[0045] 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.

[0046] 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 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. "Axial direction", "radial direction", "circumferential direction" and other directions are defined relative to a rotation axis X of the electric motor, wherein the axial direction is the direction of extension of the rotation axis X, the radial direction is the direction perpendicular to the rotation axis X, and the circumferential direction is the direction of a circumference around the rotation axis X.

[0047] 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.

[0048] Fig. 1 shows an electric motor rotor 100 according to an exemplary embodiment of the present disclosure. Fig. 2 schematically shows an electric motor that comprises the above electric motor rotor 100, wherein a cooling channel of the electric motor rotor 100 is depicted.

[0049] As shown in Figs. 1 and 2, the electric motor comprises an electric motor rotor 100 and an electric motor stator. The electric motor rotor 100 comprises an electric motor shaft 10 and a rotor core 20. The electric motor shaft 10 is able to rotate around a rotation axis X, and the rotor core 20 is fitted around the electric motor shaft 10 and is rotatably fixed to the electric motor shaft 10. The rotor core 20 comprises two end plates 21 and a lamination assembly 22 that is arranged between the two end plates 21. The lamination assembly 22 is formed by stacking multiple laminations together. The multiple laminations comprise two types of laminations, which are respectively one or more middle laminations 22a located at an axial middle position of the rotor core 20, and multiple side laminations 22b located at two sides of the middle lamination 22a. As shown in Fig. 1 , the one or more middle laminations 22a form a middle section located at a middle position of the rotor core 20, and the multiple side laminations 22b respectively form two side sections located at two sides of the middle section. The two end plates 21 tightly squeeze these laminations together, to ensure rigidity and strength of the electric motor rotor.

[0050] Referring to Fig. 5, the middle lamination 22a comprises a first stress elimination hole 221, which is used for eliminating stress that is generated by tightly fitting the middle lamination 22a around the electric motor shaft 10. The first stress elimination hole 221 is approximately in the shape of an arc, and multiple first stress elimination holes 221 (6 being shown in Fig. 5) are arranged evenly in a circumferential direction. The middle lamination 22a is further provided with a mounting hole 224, which is used for mounting a rotor magnet (not shown in the figures). As shown in Fig. 5, the middle lamination 22a comprises six groups of mounting holes 224 that are arranged evenly in a circumferential direction, each group of mounting holes 224 comprising 4 mounting holes 224 that do not communicate with each other. These 4 mounting holes 224 comprise two first mounting holes 224a and two second mounting holes 224b. The two first mounting holes 224a are located on a radial inner side and are larger in size, and an angle jointly formed thereby forms a large V shape. The two second mounting holes 224b are located on a radial inner side and are smaller in size, and an angle jointly formed thereby forms a small V shape. The first mounting hole 224a is suited for mounting a rotor magnet with a smaller volume, and the second mounting hole 224b is suited for mounting a rotor magnet with a larger volume.

[0051] Referring to Fig. 6, the side lamination 22b comprises a second stress elimination hole 223, which is used for eliminating stress that is generated by tightly fitting the side lamination 22b around the electric motor shaft 10. The second stress elimination hole 223 is approximately in the shape of an arc, and multiple second stress elimination holes 223 (6 being shown in Fig. 6) are arranged evenly in a circumferential direction. The side lamination 22b is also provided with a mounting hole 224, which is used for mounting a rotor magnet 23. As shown in Fig. 6, the side lamination 22b likewise comprises six groups of mounting holes 224 that are arranged evenly in a circumferential direction, each group of mounting holes 224 comprising 4 mounting holes 224 that do not communicate with each other. These 4 mounting holes 224 comprise two first mounting holes 224a and two second mounting holes 224b. The two first mounting holes 224a are located on a radial inner side and are larger in size, and an angle jointly formed thereby forms a large V shape. The two second mounting holes 224b are located on a radial inner side and are smaller in size, and an angle jointly formed thereby forms a small V shape. The first mounting hole 224a is suited for mounting a rotor magnet 23a with a larger volume, and the second mounting hole 224b is suited for mounting a rotor magnet 23b with a smaller volume. Mounting holes 224 of the side lamination 22b and the middle lamination 22a are aligned with each other, to facilitate inserting and mounting the rotor magnet therein.

[0052] A cooling medium circulates inside the electric motor to cool various portions of the electric motor. For example, the cooling medium may be cooling oil. Referring to Fig. 9, the electric motor shaft 10 of the electric motor rotor 100 may be provided with a central hole 11 and a communicating hole 12 that communicates with the central hole 11. The communicating hole 12 is located at an approximately middle axial position of the electric motor shaft 10, and multiple communicating holes 12 (6 being shown in Fig. 9) are distributed evenly in a circumferential direction. The cooling medium flows into the electric motor shaft 10 from the central hole 11, and flows out from the communicating hole 12. The rotor core 20 of the electric motor rotor 100 is internally provided with a cooling channel 30. Cooling medium that flows out from the communicating hole 12 flows into the cooling channel 30, and flows out from the cooling channel 30 to the electric motor rotor 100. Next, under the drive of a centrifugal force, the cooling medium can spray onto and cool other components of the electric motor, such as a winding end of the electric motor stator.

[0053] As shown in Fig. 2, the cooling channel 30 sequentially comprises an inlet section 31, a front circulation section 32, a turned back section 33, a back circulation section 34 and an outlet section 35. The inlet section 31 communicates with the communicating hole 12 of the electric motor shaft 10, and is defined by the middle lamination 22a of the lamination assembly 22. The front circulation section 32 passes from the inlet section 31 into the turned back section 33 arranged on one end plate 21 of the two end plates 21. The front circulation section 32 is defined by a side lamination 22b located on one side of the middle lamination 22a. The turned back circulation section 33 communicates with the front circulation section 32 and the back circulation section 34. The back circulation section 34 passes from the turned back section 33 into the outlet section 35 arranged on the other end plate 21. The back circulation section 34 as a whole is located on a radial outer side of the front circulation section 32, and fully penetrates the lamination assembly 22 axially. The turned back section 33 and the outlet section 35 of the cooling channel 30 are located on different end plates 21.

[0054] Referring to Figs. 5 and 6, the middle lamination 22a is further provided with a fluid inlet 222, by which a first stress elimination hole 221 communicates with a middle through hole of the middle lamination 22a. After the electric motor shaft 10 is inserted into this middle through hole, the fluid inlet 222 is flush with the communicating hole 12, so that the first stress elimination hole 221 communicates with the communicating hole 12. The first stress elimination hole 221 and the fluid inlet 222 of the middle lamination 22a form an inlet section 31 of the cooling channel 30. A second stress elimination hole 223 of the side lamination 22b is isolated from the middle through hole. This second stress elimination hole 223 is partially aligned with the first stress elimination hole 221 (preferably fully aligned), forming the front circulation section 32 of the cooling channel 30.

[0055] The turned back section 33 of the cooling channel 30 is shown in detail in Figs. 3 and 4. Specifically, the turned back section 32 is formed by a Y-shaped turned back recess 211 on the end plate 21. The turned back recess 211 comprises a receiving part 212 that communicates with the front circulation section 32, a return part 213 that communicates with the back circulation section 34, and a turned back channel 214 by which the receiving part 212 communicates with the return part 213. The shape of the receiving part 212 corresponds to the second stress elimination hole 223, and the two are at least partially aligned (preferably fully aligned). The return part 213 has a V shape, which is located on a radial outer side of the receiving part 212 but is not radially open toward the outside of the end plate 21. The turned back channel 214 extends approximately radially from the receiving part 212, and is connected to the return part 213 at the top of the V shape of the return part 213.

[0056] The back circulation section 34 of the cooling channel 30 is formed by the mounting holes 224 on the middle lamination 22a and the side laminations 22b. As shown in Fig. 6, a rotor magnet 23 only occupies a middle portion of the mounting hole 224, and a portion of the mounting hole 224 that is not occupied by the rotor magnet 23 allows cooling medium to flow, forming the back circulation section 34. The mounting holes 224 of the middle lamination 22a and the side laminations 22b are at least partially aligned with each other (preferably fully aligned), forming a back circulation section 34 that penetrates the whole lamination assembly 22. This back circulation section 34 guides cooling medium to the outlet section 33 of the other end plate 21. The cooling medium flowing in the back circulation section 34 directly contacts the rotor magnet 23, thereby enabling a good cooling effect.

[0057] Referring to Figs. 3 and 4, the outlet section 33 of the cooling channel 30 is formed by the outlet recess 215 on the end plate 21. The outlet recess 215 is open toward the outside of the electric motor rotor 100, for example being open outward in a radial direction. Thus, cooling medium that is guided to the outlet section 33 by means of the back circulation section 34 can be radially sprayed outward under the action of hydraulic and centrifugal forces, for example being sprayed onto a winding end of the electric motor stator.

[0058] The rotor core 20 of the electric motor rotor 100 may comprise multiple cooling channels 30 that are distributed evenly in a circumferential direction around the rotation axis X. The turned back sections 33 and the outlet sections 35 of these cooling channels 30 are staggered in a circumferential direction on the same end plate 21. For example, the turned back sections 33 of certain cooling channels 30 are located on one end plate 21, and outlet sections 35 of circumferentially adjacent cooling channels 30 are located on the same end plate 21. In addition, the turned back section 33 and the outlet section 35 of the same cooling channel 30 are axially opposite; that is, the turned back recess 211 of one end plate 21 is axially opposite the outlet recess 215 of the other end plate 21. That is, one of the two end plates 21 of the rotor core 20 must be rotated by a certain rotation angle relative to the other. Regarding the electric motor rotor 100 that comprises the electric motor shaft 10 comprising n communicating holes 12, this rotation angle is 3607n or an odd multiple of 3607n. For example, regarding the electric motor rotor 100 comprising 6 communicating holes 12 shown in the figures, a rotation angle between two end plates 21 may be 60°. To further increase the number of cooling channels 30, improving the uniformity of cooling of the rotor core 20, the rotor core 20 internally comprises two types of cooling channels 30, respectively a first cooling channel 30a and a second cooling channel 30b.

[0059] Referring to Fig. 7, the first cooling channel 30a and the second cooling channel 30b at the same circumferential position have a shared inlet section 31, and a first front circulation section 32a of the first cooling channel 30a and a second front circulation section 32b of the second cooling channel 30b respectively extend in opposite axial directions to end plates 21 located at two sides. The first front circulation section 32a and the second front circulation section 32b are respectively defined by the second stress elimination holes 223 of the side laminations 22b located at two sides of the middle lamination 22a.

[0060] The first cooling channel 30a comprises a first turned back section 33a located on the end plate 21, the first front circulation section 32a passing into this first turned back section 33a. The second cooling channel 30b comprises a second turned back section 33b located on the other end plate 21, the second front circulation section 32b passing into this second turned back section 33b.

[0061] Further referring to Figs. 3 and 4, the end plate 21 is provided with two different types of turned back recesses 211, comprising a first turned back recess 211a that forms the first turned back section 33a and a second turned back recess 211b that forms the second turned back section 33b. The first turned back recess 211a and the second turned back recess 211b are separated in a circumferential direction, and are staggered in the circumferential direction. The first return part 213a of the first turned back recess 211a is larger in size and radially closer to the inside, whereas the second return part 213b of the second turned back recess 211b is smaller in size and radially closer to the outside.

[0062] The first cooling channel 30a further comprises a first back circulation section 34a that communicates with the first turned back section 33 a. The second cooling channel 30b further comprises a second back circulation section 34b that communicates with the second turned back section 33b. The second back circulation section 34b and the first back circulation section 34a are located at different radial positions. In particular, the second back circulation section 34b overall is located at a radial outer side of the first back circulation section 34a.

[0063] As already described above, mounting holes 224 of the middle lamination 22a and the side laminations 22b comprise first mounting holes 224a and second mounting holes 224b. The two first mounting holes 224a are located on a radial inner side and are larger in size, and an angle jointly formed thereby forms a large V shape. The two second mounting holes 224b are located on a radial inner side and are smaller in size, and an angle jointly formed thereby forms a small V shape. Two first mounting holes 224a are aligned with the first return part 213a, forming the first back circulation section 34a, and this first back circulation section 34a comprises two branches 34al and 34a2. Two second mounting holes 224b are aligned with the second return part 213b, forming the second back circulation section 34b, and this second back circulation section 34b comprises two branches 34b 1 and 34b2.

[0064] The first cooling channel 30a further comprises a first outlet section 35a that communicates with the first back circulation section 34a. The second cooling channel 30b further comprises a second outlet section 35b that communicates with the second back circulation section 34b. The first outlet section 35a and the second outlet section 35b are respectively located on different end plates 21.

[0065] Further referring to Figs. 3 and 4, the outlet recess 215 of the end plate 21 comprises a first outlet recess 215a and a second outlet recess 215b. The first outlet recess 215a and the second outlet recess 215b are separated in a circumferential direction, and are staggered in the circumferential direction. Two first outlet recesses 215a are located on a radial inner side and are larger in size, and an angle jointly formed thereby forms a large V shape. Two second outlet recesses 215b are located on a radial outer side and are smaller in size, and an angle jointly formed thereby forms a small V shape. Two first outlet recesses 215a are aligned with the first back circulation section 34a, forming the first outlet section 35a, and this first outlet section 35a comprises two branches 35al and 35a2. The two branches 35al and 35a2 of the first outlet section 35a are both able to spray cooling medium. Two second outlet recesses 215b are aligned with the second back circulation section 34b, forming the second outlet section 35b, and this second outlet section 35b comprises two branches 35bl and 35b2. The two branches 35bl and 35b2 of the second outlet section 35b are both able to spray cooling medium.

[0066] Therefore, a communicating hole 12 of the electric motor shaft 10 corresponds to two cooling channels of the same shared inlet section, and corresponds to four back circulation section branches that can accommodate rotor magnets, and four cooling medium spray holes (two cooling medium spray holes are on each end plate). The electric motor shaft 10 of the electric motor rotor 100 shown in the figures comprises 6 communicating holes 12, and accordingly comprises 24 back circulation section branches and 24 cooling medium spray holes, 12 on each end plate 21.

[0067] Regarding the same end plate 21, the first turned back recess 211a and the second outlet recess 215b radially overlap, and the first outlet recess 215a and the second turned back recess 211b radially overlap. In the embodiment shown in Figs. 3 and 4, the first turned back plate 211 a is located at a radial inner side of the second outlet recess 215b, and the second outlet recess 215a is located at a radial inner side of the second turned back recess 211b. That is, the first turned back section 33a of the first cooling channel 30a is located at a radial inner side of the second outlet section 35b of the second cooling channel 30b, and the first outlet section 35a of the first cooling channel 30a is located at a radial inner side of the second turned back section 33b of the second cooling channel 30b.

[0068] Fig. 8 shows a first cooling channel 30a and a second cooling channel 30b that are circumferentially adjacent to the first cooling channel 30a and the second cooling channel 30b shown in Fig. 7. In the circumferential direction, the first turned back section 33a and the first outlet section 35a of the first cooling channel 30a are staggered. This can also be seen in the end plate 21 shown in Figs. 3 and 4. Circumferentially adjacent to the first turned back recess 211a that forms the first turned back section 33a is the first outlet recess 215a that forms the first outlet section 35a, and circumferentially adjacent to the second turned back recess 211b that forms the second turned back section 33b is the second outlet recess 215b that forms the second outlet section 35b. By means of the above construction of the cooling channel, cooling medium can be evenly distributed in the rotor core 20 and can fully cool various portions of the rotor core 20, particularly the rotor magnets, and can spray other portions (such as a winding end of the stator) of the electric motor at more spray holes.

[0069] According to another aspect of the present disclosure, an electric drive apparatus is proposed, comprising the electric motor as described above.

[0070] According to another aspect of the present disclosure, a vehicle is proposed, comprising the electric drive apparatus 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 vehicle.

[0071] Certain features, structures or characteristics in one or more embodiments of the present disclosure may be combined appropriately.

[0072] 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 a description of the present disclosure, and the present disclosure should not be regarded as being limited to the specific embodiments disclosed; moreover, modifications to the disclosed embodiments and other embodiments are intended to be included in the scope of the present disclosure.

Claims

Claims1. An electric motor rotor (100), characterised in that the electric motor rotor (100) comprises: an electric motor shaft (10), which is capable of rotating around a rotation axis X, and comprises a central hole (11) and a communicating hole (12) that communicates with the central hole (11); a rotor core (20), which is fitted around the electric motor shaft (10) and is rotatably fixed to the electric motor shaft (10), the rotor core (20) comprising two end plates (21) and a lamination assembly (22) that is arranged between the two end plates (21), wherein the rotor core (20) is internally provided with at least one cooling channel (30) for a cooling medium to flow in, the cooling channel (30) comprising: an inlet section (31) that communicates with the communicating hole (12); an outlet section (35) that is arranged in one end plate (21) of the two end plates (21); a turned back section (33) that is arranged in the other end plate (21) of the two end plates (21); a front circulation section (32) by which the inlet section (31) communicates with the turned back section (33); and a back circulation section (34) by which the turned back section (33) communicates with the outlet section (35).

2. The electric motor rotor (100) according to Claim 1, characterised in that the communicating hole (12) is located at an axial middle position of the electric motor shaft (10).

3. The electric motor rotor (100) according to Claim 1 or 2, characterised in that the turned back section (33) of the cooling channel (30) is a turned back recess (211) that is formed in the other end plate (21) of the two end plates (21), wherein the turned back recess (211) comprises a receiving part (212) that communicates with the front circulation section (32), a return part (213) thatcommunicates with the back circulation section (34), and a turned back channel(214) by which the receiving part (212) communicates with the return part (213).

4. The electric motor rotor (100) according to Claim 3, characterised in that the return part (213) is located at a radial outer side of the receiving part (212).

5. The electric motor rotor (100) according to Claim 3, characterised in that the return part (213) has a V shape, and the turned back channel (214) is connected to the return part (213) at the top of the V shape.

6. The electric motor rotor (100) according to Claim 3, characterised in that the outlet section (35) of the cooling channel (30) is an outlet recess (215) that is formed on said one end plate (21) of the two end plates (21), and the outlet recess(215) is open toward the outside of the electric motor rotor (100).

7. The electric motor rotor (100) according to Claim 6, characterised in that the outlet recess (215) is open on a radial edge of said one end plate (21).

8. The electric motor rotor (100) according to Claim 3, characterised in that the lamination assembly (22) comprises a middle lamination (22a), a first stress elimination hole (221) and a fluid inlet (222) that connects the first stress elimination hole (221) to the communicating hole (12) being provided on the middle lamination (22a), and the first stress elimination hole (221) and the fluid inlet (222) forming the inlet section (31) of the cooling channel (30).

9. The electric motor rotor (100) according to Claim 8, characterised in that the lamination assembly (22) further comprises a side lamination (22b) that is arranged at two sides of the middle lamination (22a), a second stress elimination hole (223) being provided on the side lamination (22b), the second stress elimination hole (223) being at least partially aligned with the first stress elimination hole (221), and the second stress elimination hole (223) forming the front circulation section (32) of the cooling channel (30).

10. The electric motor rotor (100) according to Claim 9, characterised in that the middle lamination (22a) and the side lamination (22b) are further provided with a mounting hole (224) for mounting a rotor magnet (23), the mounting holes (224) of the middle lamination (22a) and the side lamination (22b) being at least partially aligned with each other, forming the back circulation section (34) of the coolingchannel (30).

11. The electric motor rotor (100) according to Claim 10, characterised in that the back circulation section (34) of the cooling channel (30) comprises two branches formed by two mounting holes (224), and the outlet section (35) of the cooling channel (30) comprises two branches formed by two outlet recesses (215).

12. The electric motor rotor (100) according to Claim 6, characterised in that the rotor core (20) is internally provided with multiple cooling channels (30) that are distributed circumferentially, and turned back recesses (211) and outlet recesses (215) of the multiple cooling channels (30) are circumferentially staggered on the same end plate (21).

13. The electric motor rotor (100) according to Claim 10, characterised in that the cooling channel (30) that is arranged in the rotor core (20) comprises a first cooling channel (30a) and a second cooling channel (30b), the first cooling channel (30a) and the second cooling channel (30b) having a joint inlet section (31), and the first cooling channel (30a) further comprises a first front circulation section (32a), a first turned back section (33a), a first back circulation section (34a) and a first outlet section (35a); the second cooling channel (30b) further comprises a second front circulation section (32b), a second turned back section (33b), a second back circulation section (34b) and a second outlet section (35b).

14. The electric motor rotor (100) according to Claim 13, characterised in that the first front circulation section (32 a) and the second front circulation section(32b) extend in opposite axial directions, the first back circulation section (34a) and the second back circulation section (34b) are located at different radial positions, the first turned back section (33 a) and the second outlet section (35b) are arranged on one end plate (21), and the first outlet section (35a) and the second turned back section (33b) are arranged on the other end plate (21).

15. The electric motor rotor (100) according to Claim 13 or 14, characterised in thatthe turned back recess (211) comprises a first turned back recess (211a) that forms the first turned back section (33a) and a second turned back recess (211b) that forms the second turned back section (33b), the mounting hole (224) comprises a first mounting hole (224a) that forms the first back circulation section (34a) and a second mounting hole (224b) that forms the second back circulation section (34b), the outlet recess (215) comprises a first outlet recess (215a) that forms the first outlet section (35a) and a second outlet recess (215b) that forms the second outlet section (35b).

16. The electric motor rotor (100) according to Claim 15, characterised in that the first turned back recess (211a) and the second outlet recess (215b) radially overlap on the same end plate (21), and the first outlet recess (215a) and the second turned back recess (211b) radially overlap on the same end plate (21).

17. The electric motor rotor (100) according to Claim 1, characterised in that two end plates (21) of the rotor core (20) are rotated by 360 n relative to each other, wherein n is a number of communicating holes (12) that are arranged on the electric motor shaft (10).

18. An electric motor, characterised in that the electric motor comprises the electric motor rotor (100) according to any one of Claims 1 to 17.

19. An electric drive apparatus, characterised in that the electric drive apparatus comprises the electric motor according to Claim 18.

20. A vehicle, characterised in that the vehicle comprises the electric drive apparatus according to Claim 19.

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