Oil-cooled motor, power assembly and electric vehicle

Abstract

The embodiment of the invention provides an oil-cooled motor, a power assembly and an electric vehicle, relates to the technical field of motors, and is used for solving the problem of poor heat dissipation of a rotor. The rotor of the oil-cooled motor comprises a rotor core and an end plate. The end plate comprises a plurality of groups of grooves, and the plurality of groups of grooves are located at one side, facing the rotor core, of the end plate. The distances between the multiple sets of grooves and the peripheral face of the end plate are not equal. And each groove in one group of grooves in the plurality of groups of grooves is used for receiving oil liquid of at least one internal flow channel of the rotor iron core and discharging cooling oil in the rotor. And the radial size of each groove in one group of grooves is smaller than that of each groove in other groups of grooves. And the circumferential size of each groove in one group of grooves is smaller than that of each groove in other groups of grooves. By limiting the flow of the cooling oil flowing out of the interior of the rotor, the circulation time of the cooling oil in the rotor iron core is prolonged, so that the cooling effect of the rotor is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric machines, in particular to an oil-cooled electric machine, a power assembly and an electric vehicle. BACKGROUND

[0002] With the development of new energy vehicles, the electric machine of the power assembly is developing towards high speed, high power density and miniaturization. However, with the continuous increase of the speed and power density of the electric machine, the eddy current loss and hysteresis loss of the rotor of the electric machine increase sharply, resulting in an increase in the heat generated by the rotor, and the heat is highly concentrated in the rotor. The higher the speed of the electric machine, the more difficult it is to dissipate the heat inside the rotor, which seriously affects the overall performance of the electric machine. SUMMARY

[0003] The present application provides an oil-cooled electric machine, a power assembly and an electric vehicle to improve the cooling effect of the rotor.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0005] The first aspect of the present application provides an oil-cooled electric machine, the rotor of the oil-cooled electric machine comprising a rotor core and an end plate. The end plate comprises a plurality of groups of grooves, and the plurality of groups of grooves are located on the side of the end plate facing the rotor core. The spacing between the plurality of groups of grooves and the outer circumferential surface of the end plate is not equal.

[0006] Among the plurality of groups of grooves, each groove in one group of grooves is used to receive the oil of at least one internal flow channel of the rotor core and to discharge the cooling oil inside the rotor. The radial dimension of each groove in one group of grooves is smaller than the radial dimension of each groove in the other groups of grooves. The circumferential dimension of each groove in one group of grooves is smaller than the circumferential dimension of each groove in the other groups of grooves.

[0007] In the oil-cooled electric machine given in the present application, the spacing between the plurality of groups of grooves and the outer circumferential surface of the rotor end plate is not equal, so that the plurality of groups of grooves are connected with the internal flow channels in different regions of the rotor core in the radial direction, forming a plurality of layers of oil liquid channels. The cooling oil flows to different positions of the rotor core under the action of centrifugal force to take away the heat of different positions of the rotor core, which is beneficial to improve the cooling effect of the rotor.

[0008] Each groove in one group of grooves among the plurality of groups of grooves is used to receive the oil of at least one internal flow channel of the rotor core and to discharge the cooling oil inside the rotor, so that the cooling oil inside the rotor is discharged from the inside of the rotor through the one group of grooves, and the radial dimension and the circumferential dimension of each groove in the one group of grooves are the smallest, so as to limit the flow of the cooling oil flowing out of the inside of the rotor per unit time, increase the flow time of the cooling oil in the rotor core, and increase the heat exchange time of the cooling oil and the rotor core, thereby improving the cooling efficiency of the rotor and ensuring the operation reliability of the oil-cooled electric machine.

[0009] In one embodiment, the distance between one set of grooves and the outer peripheral surface of the end plate is smaller than the distance between other sets of grooves and the outer peripheral surface of the end plate. Specifically, the distance between each groove in one set of grooves and the outer peripheral surface of the end plate is greater than the distance between each groove in one set of grooves and the inner peripheral surface of the end plate.

[0010] In the oil-cooled motor provided in this application, one set of grooves in the radial direction of the rotor is located on the outermost side of the other sets of grooves, and one set of grooves is closer to the inner circumferential surface of the end plate. Therefore, the multiple sets of grooves are closer to the inner circumferential surface of the end plate as a whole, so that the multiple sets of grooves are arranged compactly in the radial direction of the end plate.

[0011] Compared to designs where multiple sets of grooves are radially dispersed on the end plate, this application uses multiple sets of grooves close to the inner circumferential surface of the end plate and arranges them compactly in the radial direction of the end plate, thereby reducing the resistance of the cooling oil in the flow channel. Under the same conditions, the reduced resistance of the cooling oil in the flow channel helps to increase the flow rate of the cooling oil, which in turn helps to increase the heat carried away by the cooling oil per unit time, thus improving the heat dissipation of the rotor.

[0012] Furthermore, the multiple sets of grooves are arranged compactly near the inner circumference of the end plate, which reduces the flow length and flow time of the cooling oil on the end plate. Under the same flow rate, the flow length and flow time of the cooling oil on the end plate are reduced, which increases the flow time of the cooling oil in the rotor core and increases the heat exchange time between the cooling oil and the rotor, thereby improving the cooling efficiency of the rotor.

[0013] In one embodiment, a portion of each groove in a set of grooves is used to communicate with at least one internal flow channel. The bottom of another portion of each groove in the set of grooves includes an oil outlet. The oil outlet extends through the end plate along the rotor's axial direction. The distance between a portion of each groove in the set of grooves and the inner circumferential surface of the end plate is less than the distance between the oil outlet and the inner circumferential surface of the end plate.

[0014] In this set of grooves, the circumferential dimension of another part of each groove is smaller than the circumferential dimension of a part of each groove in the set of grooves, but larger than the diameter of the oil outlet hole.

[0015] During rotor operation, the cooling oil in each groove of a set of grooves is thrown onto the side wall near the outer circumference of the end plate by centrifugal force. To facilitate the cooling oil being thrown out of the end plate, oil outlet holes are arranged at the bottom of the other part of each groove in the set of grooves. The oil outlet holes are placed on the other part of each groove in the set of grooves near the outer circumference of the end plate, ensuring that the cooling oil is quickly discharged from the oil outlet holes. This reduces the flow time of the cooling oil in the end plate and reduces the possibility of eddies or dead zones generated by the cooling oil in the set of grooves, thereby enhancing the rotor's heat dissipation effect.

[0016] A portion of each groove in a set of grooves is used to connect with at least one internal flow channel of the rotor core, and another portion is used to discharge cooling oil. By limiting the circumferential dimension of the other portion of each groove in a set of grooves to be smaller than the circumferential dimension of a portion of each groove in a set of grooves, the flow rate of cooling oil flowing through the other portion of each groove in a set of grooves per unit time is reduced during the flow of cooling oil from a portion of each groove in a set of grooves to the other portion of each groove in a set of grooves. This prolongs the flow time of cooling oil in the rotor core, increases the heat exchange time between the cooling oil and the rotor, and thus helps to improve the cooling efficiency of the rotor.

[0017] By limiting the circumferential dimension of the other part of each groove in a set of grooves to be smaller than the diameter of the oil outlet hole, the flow rate of cooling oil flowing through the oil outlet hole per unit time is reduced during the process of cooling oil flowing from the other part of each groove in a set of grooves to the oil outlet hole. This helps to prolong the flow time of cooling oil in the rotor core, thereby improving the cooling efficiency of the rotor.

[0018] In one embodiment, the radial dimension of a portion of each groove in a set of grooves is smaller than the diameter of the oil outlet hole and larger than the distance between a portion of each groove in the set of grooves and the oil outlet hole.

[0019] By limiting the radial dimension of each groove in a set of grooves, the radial space occupied by the set of grooves is reduced, which facilitates a compact radial arrangement of multiple sets of grooves. A smaller radial dimension for each groove in a set also shortens the length and time of the cooling oil flow radially within the set of grooves. At the same flow rate, the reduced flow length and time of the cooling oil on the end plate increases the flow time of the cooling oil within the rotor core, thereby increasing the heat exchange time between the cooling oil and the rotor and improving the rotor's cooling efficiency.

[0020] In one embodiment, the distance between another set of grooves and the inner circumferential surface of the end plate is less than the distance between the first set of grooves and the inner circumferential surface of the end plate. Each groove in the other set of grooves is used to connect at least two internal flow channels of the rotor core. The circumferential dimension of each groove in the other set of grooves is greater than the radial dimension of each groove in the other set of grooves.

[0021] By limiting the radial dimension of each groove in the other set of grooves, the radial space occupied by the other set of grooves is reduced, which facilitates a compact radial arrangement of multiple sets of grooves. The smaller radial dimension of each groove in the other set also shortens the length and time of the cooling oil flow in the radial direction. At the same flow rate, the reduced flow length and time of the cooling oil on the end plate increases the flow time of the cooling oil within the rotor core, thereby increasing the heat exchange time between the cooling oil and the rotor and improving the rotor's cooling efficiency.

[0022] In one embodiment, each groove in another set of grooves includes multiple groove segments. The multiple groove segments include a first groove segment, a second groove segment, and a third groove segment. The first, second, and third groove segments are arranged sequentially along the radial direction of the rotor. The distance between the first groove segment and the inner circumferential surface of the end plate is less than the distance between the third groove segment and the inner circumferential surface of the end plate. The first and third groove segments are respectively used to connect different internal flow channels.

[0023] The area of ​​the third tank segment is larger than that of the second tank segment but smaller than that of the first tank segment.

[0024] The area of ​​the first slot is larger than that of the second and third slots, which limits the overall flow rate of cooling oil from the first slot to the third slot per unit time. This reduces the flow rate of cooling oil from the internal flow channel of the rotor core to the first slot, ensuring the flow time of the cooling oil in the internal flow channel, and thus improving the heat dissipation efficiency of the rotor.

[0025] The area of ​​the third slot is larger than that of the second slot, which reduces the flow rate of the cooling oil entering the third slot from the second slot. This reduces the flow rate of the oil entering the internal flow channel, which on the one hand helps the cooling oil to enter the internal flow channel of the rotor core more evenly, and on the other hand helps to increase the heat exchange time between the cooling oil and the rotor core.

[0026] In addition, the second groove has the smallest area. When the cooling oil is transported from the first groove to the second groove, the flow rate increases sharply and it quickly enters the second groove, thereby reducing the flow time of the cooling oil in the second groove. This helps to increase the heat exchange time between the cooling oil in the rotor core and the rotor core.

[0027] In one embodiment, the circumferential dimension of the third groove segment is greater than the circumferential dimension of the second groove segment and less than the circumferential dimension of the first groove segment. The radial dimension of the second groove segment is greater than the radial dimension of the third groove segment and less than the radial dimension of the first groove segment.

[0028] The first slot has the largest circumferential dimension, ensuring that the cooling oil entering from the internal channels of the rotor core is evenly distributed within the circumferential range of the first slot, and reducing the flow velocity of the cooling oil, thus playing a stabilizing role. The first slot also has the largest radial dimension, providing a larger radial path for the cooling oil entering the first slot, ensuring that the cooling oil gains greater kinetic energy, and providing a greater driving force for the flow of subsequent cooling oil.

[0029] The second slot has the smallest circumferential dimension. This serves two purposes: firstly, it controls the flow rate of cooling oil from the first slot to the third slot; secondly, it increases the cooling oil velocity, allowing it to quickly enter the third slot and reducing its transit time within the second slot. Because the second slot has the smallest circumferential dimension, its radial dimension is larger than that of the third slot but smaller than that of the first slot. This enhances the structural strength of the second slot, ensuring sufficient rigidity and strength even at high speeds, thus guaranteeing the rotor's operational safety.

[0030] The circumferential dimension of the third slot is smaller than that of the first slot but larger than that of the second slot. This reduces the flow velocity of the cooling oil entering the third slot from the second slot, helping to ensure more uniform distribution of the cooling oil within the rotor core's internal flow channels. The third slot also has the smallest radial dimension. This design allows the cooling oil to flow radially along the end plate within the third slot, limiting the generation of axial eddies and ensuring precise entry of the cooling oil into the rotor core's internal flow channels. Furthermore, it maximizes the area of ​​the solid portion of the end plate's outer circumference, improving its structural strength and rigidity and preventing deformation or tearing under high-speed rotation.

[0031] In one embodiment, the radial dimension of each slot segment is smaller than its circumferential dimension.

[0032] By limiting the radial dimension of each slot segment, the radial space occupied by another set of grooves is reduced, which facilitates a compact radial arrangement of multiple sets of grooves. The smaller radial dimension of each slot segment also shortens the length and time of the cooling oil flow radially through the other set of grooves. At the same flow rate, the reduced flow length and time of the cooling oil on the end plate increases the flow time of the cooling oil within the rotor core, thereby increasing the heat exchange time between the cooling oil and the rotor and improving the rotor's cooling efficiency.

[0033] In one embodiment, the distance between another set of grooves and the outer peripheral surface of the end plate is greater than the distance between the other sets of grooves and the outer peripheral surface of the end plate. A portion of each groove in the other set is used to receive cooling oil supplied by the motor shaft of the oil-cooled motor. Another portion of each groove in the other set is used to supply cooling oil to at least one internal flow channel of the rotor core.

[0034] In one set of grooves, the radial dimension of a portion of each groove is greater than the radial dimension of another portion of each groove in the other set of grooves. Conversely, the circumferential dimension of a portion of each groove in the other set of grooves is smaller than the circumferential dimension of another portion of each groove in the other set of grooves.

[0035] In the oil-cooled motor disclosed in this application, one set of grooves in a plurality of radial grooves along the rotor is located at the innermost side of the other sets of grooves. The cooling oil delivered by the motor shaft enters the corresponding groove through a portion of each groove in the other set of grooves, and is supplied to the internal flow channel of the rotor core through another portion of each groove in the other set of grooves.

[0036] In one of the grooves, a portion of each groove has a large radial dimension and a small circumferential dimension to increase the flow rate of the cooling oil. This ensures that the cooling oil quickly enters the corresponding portion of the groove in the other set of grooves, shortening the length and time of the cooling oil's radial flow in the other set of grooves. Under the same flow rate, the flow length and flow time of the cooling oil on the end plate are reduced, which increases the flow time of the cooling oil in the rotor core and the heat exchange time between the cooling oil and the rotor, thus improving the cooling efficiency of the rotor.

[0037] In another set of grooves, a portion of the circumferential dimension of each groove is smaller than the circumferential dimension of another portion of each groove in the other set of grooves. This reduces the flow rate of the cooling oil and acts as a pressure stabilizer, thereby reducing the flow rate of the oil entering the internal flow channel of the rotor core. The oil flows slowly in the internal flow channel, increasing the heat exchange time, which helps to improve the heat exchange efficiency between the cooling oil and the rotor core.

[0038] In one embodiment, the radial dimension of another portion of each groove in another set of grooves is smaller than the circumferential dimension of a portion of each groove in another set of grooves.

[0039] By limiting the radial dimension of another portion of each groove in the other set of grooves, the radial space occupied by the other set of grooves is reduced, which facilitates a compact radial arrangement of multiple sets of grooves. The smaller radial dimension of each groove in the other set also shortens the length and time of the cooling oil's radial flow within the other set of grooves. At the same flow rate, the reduced flow length and time of the cooling oil on the end plate increases the flow time of the cooling oil within the rotor core, thereby increasing the heat exchange time between the cooling oil and the rotor and improving the rotor's cooling efficiency.

[0040] In one embodiment, the multiple internal flow channels include multiple sets of internal flow channels. The multiple sets of internal flow channels are arranged at intervals along the circumference of the rotor. Each set of internal flow channels includes a first internal flow channel and a second internal flow channel. The first and second internal flow channels in each set are arranged at intervals along the radial direction of the rotor. The first internal flow channel is used to receive cooling oil supplied by the motor shaft of the oil-cooled motor through a recess. The second internal flow channel is used to discharge cooling oil through another recess.

[0041] The distance between the first internal flow channel and the inner circumferential surface of the rotor core is smaller than the distance between the second internal flow channel and the inner circumferential surface of the rotor core. The area of ​​the first internal flow channel is larger than the area of ​​the second internal flow channel.

[0042] In the oil-cooled motor disclosed in this application, the first internal flow channel is closer to the inner circumferential surface of the rotor core, and the second internal flow channel is closer to the outer circumferential surface of the rotor core. The first internal flow channel has a larger area, which reduces the flow velocity of the cooling oil within it. This facilitates the uniform entry of the cooling oil into both the first and second internal flow channels and increases the contact time between the relatively low-temperature cooling oil initially entering the rotor core and the rotor core, thereby improving heat exchange efficiency. Furthermore, the larger cross-sectional area results in lower flow resistance within the first internal flow channel, increasing the flow rate of the cooling oil under the same conditions, which in turn increases the amount of heat carried away by the cooling oil per unit time.

[0043] The smaller area of ​​the first internal flow channel allows for increased cooling oil flow velocity. This increased velocity serves two purposes: firstly, it disrupts the thermal boundary layer formed by the cooling oil on the inner wall of the channel. The thermal boundary layer is a relatively static layer of oil adhering closely to the rotor core. Higher flow velocities result in a thinner thermal boundary layer, lower thermal resistance, and higher heat transfer efficiency. Secondly, it enhances turbulence, thus improving heat exchange between the cooling oil and the rotor core. Furthermore, when the cooling oil flows into the second internal flow channel, its temperature is higher than that in the first channel. The increased flow velocity in the second channel further increases the overall cooling oil flow rate, thereby improving the rotor's heat dissipation efficiency.

[0044] In one embodiment, the circumferential dimension of the first internal flow channel is larger than the circumferential dimension of the second internal flow channel. The radial dimension of the second internal flow channel is smaller than the radial dimension of the first internal flow channel and larger than the distance between the first and second internal flow channels.

[0045] In the oil-cooled motor disclosed in this application, the large circumferential dimension of the first internal flow channel facilitates the uniform distribution of cooling oil along the circumference of the rotor, preventing insufficient cooling or excessive local cooling oil flow. During high-speed rotation, centrifugal force causes the oil to be thrown onto the radial inner wall of the flow channel. The wider circumferential dimension increases the contact area between the cooling oil and the radial sidewall of the flow channel, which is beneficial to improving the heat exchange efficiency between the cooling oil and the rotor core within the first internal flow channel.

[0046] The large radial dimension of the first internal flow channel helps reduce the cooling oil flow rate, thus buffering and stabilizing the oil flow. When the rotor rotates at high speed, the centrifugal force on the cooling oil increases, and the larger radial dimension provides a radial flow path for the cooling oil, thus guiding the flow field.

[0047] The smaller circumferential dimension of the second internal flow channel reduces internal circulation or dead zones caused by excessively wide channels, thus improving the heat exchange efficiency between the cooling oil and the rotor core. Furthermore, it allows the rotor core to retain more solid material in areas of high centrifugal force, increasing the rotor's strength and rigidity. This ensures structural stability at high speeds and prevents deformation due to excessive centrifugal force.

[0048] The small radial dimension of the second internal flow channel limits the thickness of the oil film between the cooling oil and the inner wall of the channel, thereby improving heat transfer efficiency. Furthermore, it restricts the internal circulation of the cooling oil, ensuring contact between the oil and the inner wall of the second internal flow channel, further enhancing heat dissipation.

[0049] The first and second internal flow channels are spaced at the smallest distance along the radial direction of the rotor, so that the first and second internal flow channels are arranged in a compact radial layout. After the cooling oil leaves the first internal flow channel, it quickly enters the second internal flow channel under the action of stronger centrifugal force, so as to limit the eddies or dead zones that may be generated between the first and second internal flow channels, thereby enhancing heat dissipation.

[0050] In one embodiment, the rotor core includes a plurality of magnet slots. Each magnet slot is used to accommodate at least one magnet. The end plate includes a plurality of through holes spaced apart circumferentially along the rotor. The through holes penetrate the end plate axially along the rotor. Each through hole axially opposite a portion of at least one magnet slot.

[0051] The distance between the through hole and the outer circumferential surface of the end plate is greater than the distance between the set of grooves and the outer circumferential surface of the end plate. The distance between the through hole and the inner circumferential surface of the end plate is less than the distance between the set of grooves and the inner circumferential surface of the end plate.

[0052] Because the through holes are opposite a portion of at least one magnet slot, the heat from the magnets is dissipated along the through holes to the outside of the rotor, thus improving the rotor's heat dissipation. The multiple through holes on the end plate also serve to reduce weight and achieve rotor dynamic balance.

[0053] The radial through holes and a set of grooves are staggered along the rotor. While ensuring the strength and rigidity of the end plate, the magnet slots are brought close to the internal flow channels of the rotor core connected by the set of grooves, so as to enhance the heat dissipation of the magnets in the magnet slots and thus improve the heat dissipation efficiency of the rotor.

[0054] In some embodiments, the axial dimension of the through hole is greater than the radial dimension of the through hole and the circumferential dimension of the groove, so that the circumferential coverage of the through hole is larger, which is beneficial to increasing the relative area between the magnet groove and the through hole, thereby improving heat dissipation.

[0055] A second aspect of this application provides a powertrain including a reducer and the aforementioned oil-cooled motor, the oil-cooled motor being used to drive the wheels of an electric vehicle via the reducer.

[0056] Oil-cooled motors convert electrical energy into rotational mechanical energy and output torque to a reducer. The reducer reduces the rotational speed, increases the torque, and transmits power to the wheels of the electric vehicle to drive the wheels and thus propel the electric vehicle.

[0057] In addition, the powertrain provided in this application includes the aforementioned oil-cooled motor. Therefore, the powertrain provided in this application solves the same technical problem and has the same technical effect as the oil-cooled motor in the above-mentioned technical solution, and will not be repeated here.

[0058] A third aspect of this application provides an electric vehicle, the electric vehicle including wheels and the aforementioned powertrain, the powertrain being used to drive the wheels.

[0059] The powertrain is used to convert electrical energy into mechanical energy and drive the wheels to rotate, thus enabling electric vehicles to move.

[0060] Furthermore, the electric vehicle provided in this application includes the aforementioned powertrain. Therefore, the electric vehicle provided in this application solves the same technical problem and has the same technical effect as the powertrain of the aforementioned technical solution, which will not be elaborated here. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of the structure of an electric vehicle provided in an embodiment of this application;

[0062] Figure 2 This is a schematic diagram of the structure of a powertrain provided in an embodiment of this application;

[0063] Figure 3 This is a schematic diagram of the structure of an oil-cooled motor provided in an embodiment of this application;

[0064] Figure 4 A partial structural schematic diagram of an oil-cooled motor provided in an embodiment of this application;

[0065] Figure 5 for Figure 4 A partial exploded view of the Sinopec Refrigeration Motor;

[0066] Figure 6 for Figure 4 Cross-sectional view of the Sinopec refrigerated motor along the PP line;

[0067] Figure 7 A partial structural schematic diagram of a rotor core provided in an embodiment of this application;

[0068] Figure 8 One of the perspective structural diagrams of a rotor end plate provided in the embodiments of this application;

[0069] Figure 9 This is a second perspective structural diagram of a rotor end plate provided in an embodiment of this application;

[0070] Figure 10 This is a schematic diagram of the structure of a rotor end plate provided in an embodiment of this application;

[0071] Figure 11This is a schematic diagram of a rotor provided in an embodiment of this application.

[0072] Figure label:

[0073] 1000 - Electric vehicles;

[0074] 100 - Powertrain; 200 - Wheels; 300 - Transmission mechanism; 400 - Power battery;

[0075] 10 - Oil-cooled motor; 20 - Reducer;

[0076] 01-Rotor;

[0077] 1-Rotor core; 11-First center hole; 12-Internal flow channel; 12a-First internal flow channel; 12b-Second internal flow channel; 13-Magnet slot;

[0078] 2-End plate; 2a-First end plate; 2b-Second end plate; 21a-Second center hole; 21b-Third center hole; 22-Groove; 22a-First groove; 22b-Second groove; 221-Slot segment; 2211-First slot segment; 2212-Second slot segment; 2213-Third slot segment; 22c-Third groove; 23-Oil outlet; 24-Through hole;

[0079] 3-Magnet; 4-Pressure plate; 41-Fourth center hole;

[0080] 02-Stator; 021-Stator core; 022-Stator winding;

[0081] 03-Motor shaft; 031-Axial flow channel; 032-Radial oil hole; 033-Protrusion; 034-Strip groove. Detailed Implementation

[0082] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application.

[0083] In the accompanying drawings of the embodiments of this application, solid structures such as parts and components are represented by guide lines; hollow structures such as openings, holes, spaces, and cavities are represented by guide lines with arrows.

[0084] In high-speed or ultra-high-speed motors, eddy current losses and hysteresis losses in the rotor increase dramatically, leading to increased heat generation and high heat concentration within the rotor. Furthermore, the higher the rotational speed, the more difficult it is for the heat inside the rotor to dissipate, severely impacting the overall performance of the motor.

[0085] Based on this, embodiments of this application provide an oil-cooled motor, a powertrain, and an electric vehicle to improve the cooling effect of the rotor and ensure the operational reliability of the oil-cooled motor.

[0086] The electric vehicle provided in this application is a wheeled device driven or towed by a power unit. In some embodiments, the electric vehicle includes pure electric vehicles, hybrid electric vehicles, range-extended electric vehicles, or plug-in hybrid electric vehicles, etc.

[0087] Among them, pure electric vehicles are called battery electric vehicles, abbreviated as BEV. Hybrid electric vehicles are called hybrid electric vehicles, abbreviated as HEV. Range-extended electric vehicles are called range-extended electric vehicles, abbreviated as REEV. Plug-in hybrid electric vehicles are called plug-in hybrid electric vehicles, abbreviated as PHEV.

[0088] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0089] Figure 1 This is a structural schematic diagram of an electric vehicle provided as an embodiment of this application. (Refer to...) Figure 1 The electric vehicle 1000 includes a powertrain 100 and wheels 200. The powertrain 100 is used to drive the wheels 200 to rotate, thereby enabling the electric vehicle 1000 to move.

[0090] The electric vehicle 1000 also includes a transmission mechanism 300 and a power battery 400. The power battery 400 is used to supply power to the powertrain 100; the power battery 400 is also referred to as a battery pack. The transmission mechanism 300 is used to drive the powertrain 100 and the wheels 200. The powertrain 100 converts the electrical energy provided by the power battery 400 into mechanical energy, and drives the wheels 200 to rotate via the transmission mechanism 300, thereby enabling the electric vehicle 1000 to move.

[0091] Figure 2 This is a schematic diagram of a powertrain provided in an embodiment of this application. (Refer to...) Figure 2 The part shown in the dashed box is the powertrain 100. The powertrain 100 includes an oil-cooled motor 10 and a reducer 20. The oil-cooled motor 10 is used to convert electrical energy into mechanical energy, and then transmit the mechanical energy to the reducer 20. The reducer 20 converts the mechanical energy output by the oil-cooled motor 10 into a greater torque output to drive the wheels 200 to rotate.

[0092] Figure 3 This is a schematic diagram of the structure of an oil-cooled motor provided in an embodiment of this application. (Refer to...) Figure 3The letter A points in the axial direction of the oil-cooled motor 10, the letter B points in the radial direction of the oil-cooled motor 10, and the letter C points in the circumferential direction of the oil-cooled motor 10.

[0093] Reference Figure 3 The oil-cooled motor 10 includes a rotor 01, a stator 02, and a motor shaft 03. The stator 02 includes a stator core 021 and a stator winding 022, with the stator winding 022 mounted on the stator core 021. The stator core 021 surrounds the rotor 01, and there is an air gap between the stator core 021 and the rotor 01. The rotor 01 includes a rotor core 1 and magnets. The center hole of the rotor core 1 is used to accommodate and fix the motor shaft 03. The magnets are mounted on the rotor core 1. Figure 3 Not shown in the image.

[0094] The center hole of stator 02 Figure 3 As shown in a, the center hole of rotor core 1 is also called the rotor center hole. The center hole of rotor core 1 is located in... Figure 3 Not shown in the image.

[0095] The rotor 01 and stator 02 work together to convert electrical energy into mechanical energy. When the stator winding 022 is energized, it generates a rotating magnetic field. This rotating magnetic field interacts with the inherent magnetic field of the magnets in the rotor 01 to generate an electromagnetic force. This electromagnetic force acting on the rotor 01 is converted into driving torque, which drives the rotor 01 to rotate, thereby realizing the conversion of electrical energy into mechanical energy.

[0096] Since the motor shaft 03 is fixed to the center hole of the rotor 01, the motor shaft 03 rotates together with the rotor 01. The motor shaft 03 is used to transmit the rotational torque generated by the rotor 01, thereby outputting mechanical energy.

[0097] As the motor speed and power density continue to increase, the heat generated by the rotor 01 increases. Based on this, the embodiments of this application use oil cooling to cool the rotor 01 in order to improve the cooling efficiency of the rotor 01.

[0098] exist Figure 3 In the given embodiment, cooling oil is fed into the rotor 01 through the motor shaft 03 and exchanges heat with the rotor 01 to remove the heat from the rotor 01. The cooling oil after heat exchange with the rotor 01 is thrown out through the axial end of the rotor 01.

[0099] The two ends of stator winding 022 along direction A are exposed on the corresponding axial end faces of stator core 021. The portion of stator winding 022 exposed on stator core 021 is also called the end winding of stator winding 022. Due to the concentration of resistance and additional losses in the end winding of stator winding 022, the end winding of stator winding 022 generates a large amount of heat. Furthermore, the complex structure at the end winding of stator winding 022 hinders heat dissipation, resulting in a high temperature of the end winding of stator winding 022.

[0100] In some embodiments, to improve the heat dissipation effect of the end windings of the stator winding 022, the dimension of the stator winding 022 along direction A is made larger than the dimension of the rotor 01 along direction A, and the cooling oil introduced into the rotor 01 flows from the axial end of the rotor 01 along... Figure 3 The dashed arrow in the image sprays cooling oil into the end winding of stator winding 022. The cooling oil sprayed into the end winding of stator winding 022 undergoes forced convection heat exchange with the end winding of stator winding 022 to remove heat from the end winding of stator winding 022 and reduce the temperature of the end winding of stator winding 022.

[0101] In contrast to the cooling oil being thrown out from the outer periphery of the rotor 01, in this application the cooling oil is thrown out from the axial end of the rotor 01. This ensures the cooling of the end windings of the stator winding 022 while reducing the impact of the cooling oil thrown out at high speed on the end windings of the stator winding 022, and preventing damage to the stator winding 022 due to excessive oil impact force.

[0102] In the embodiments provided in this application, the cooling oil exchanges heat with the rotor 01 and stator 02 to reduce their temperatures, which helps ensure the stable operation of the oil-cooled motor 10. The insulating properties of the cooling oil also ensure the safe operation of the oil-cooled motor 10, preventing potential electrical short circuits, and the cooling oil inhibits electrochemical corrosion, which helps extend the service life of the oil-cooled motor 10.

[0103] In the embodiments of this application, the axial direction of the oil-cooled motor 10, the axial direction of the rotor 01, the axial direction of the stator 02, and the axial direction of the motor shaft 03 refer to the same direction. The radial direction of the oil-cooled motor 10, the radial direction of the rotor 01, the radial direction of the stator 02, and the radial direction of the motor shaft 03 refer to the same direction. The circumferential direction of the oil-cooled motor 10, the circumferential direction of the rotor 01, the circumferential direction of the stator 02, and the circumferential direction of the motor shaft 03 refer to the same direction.

[0104] For ease of understanding, in the following text and in the accompanying drawings of the embodiments of this application, the axial direction of the oil-cooled motor 10 is referred to by the letter A, the radial direction by the letter B, and the circumferential direction by the letter C.

[0105] Figure 4This is a partial structural diagram of an oil-cooled motor provided in an embodiment of this application. Figure 5 for Figure 4 A partial exploded view of the Sinopec refrigerated motor. (Refer to...) Figure 4 and Figure 5 The rotor 01 includes a rotor core 1 and two end plates 2, which are arranged along the A direction at both ends of the rotor core 1.

[0106] The two end plates 2 include a first end plate 2a and a second end plate 2b. The center hole of the rotor core 1 is as follows: Figure 5 The first central hole 11 is shown in the figure. The central hole of the first end plate 2a is shown in the figure. Figure 5 As shown in the second center hole 21a, the center hole of the second end plate 2b is as follows Figure 5 The third central hole 21b is shown in the figure.

[0107] Reference Figure 4 and Figure 5 The motor shaft 03 includes a protrusion 033 that extends radially outward along the rotor and is located on the side of the first end plate 2a facing away from the rotor core 1 along direction A. The rotor 01 also includes a pressure plate 4 located on the side of the second end plate 2b facing away from the rotor core 1 along direction A. The protrusion 033 and the pressure plate 4 axially lock the first end plate 2a, the rotor core 1, and the second end plate 2b onto the motor shaft 03.

[0108] During installation, the motor shaft 03 is first passed through the second center hole 21a, the first center hole 11, and the third center hole 21b in sequence, and the first end plate 2a abuts against the protrusion 033 to limit the displacement of the rotor 01 toward the protrusion 033 in the A direction. Next, the motor shaft 03 passes through and is fixed to the fourth center hole 41 of the pressure plate 4 to limit the displacement of the rotor 01 away from the protrusion 033 in the A direction.

[0109] For ease of assembly, refer to Figure 5 The motor shaft 03 includes a strip-shaped groove 034. The groove opening of the strip-shaped groove 034 faces the rotor 01 radially, and the strip-shaped groove 034 passes through one end of the motor shaft 03 in direction A. The inner circumferential surfaces of the first end plate 2a, the second end plate 2b, and the rotor core 1 all include protrusions. Each protrusion faces the motor shaft 03 radially from the rotor 01. The protrusions are as follows: Figure 5 The letter T indicates that each protrusion extends at least partially into the groove 034. During installation, the portion of each protrusion extending into the groove 034 slides along the groove 034 to provide positioning during installation and facilitate assembly.

[0110] In some embodiments, the motor shaft 03 has two strip grooves 034, which are distributed opposite each other radially along the motor shaft 03. Each end plate 2 has one protrusion, and the rotor core 1 has two protrusions. During installation, the protrusion of the end plate 2 engages with one strip groove 034, and the two protrusions of the rotor core 1 engage with different strip grooves 034 respectively.

[0111] In other embodiments of this application, the strip groove 034 of the motor shaft 03, the protrusion of the end plate 2, and the protrusion of the rotor core 1 are all one. During installation, the portion of each protrusion extending into the strip groove 034 slides along the strip groove 034 to facilitate installation. Those skilled in the art can selectively design the number and arrangement of the strip groove 034 and the protrusion according to actual needs.

[0112] In some embodiments, the rotor core 1 includes a plurality of rotor laminations arranged sequentially along direction A. The rotor laminations can take various forms. In some embodiments, the rotor laminations are high-strength silicon steel sheets. Multiple high-strength silicon steel sheets are stacked and pressed together to form the rotor core 1, thereby improving the strength and rigidity of the rotor core 1 and meeting the strength requirements of the high-speed oil-cooled motor 10 or the ultra-high-speed oil-cooled motor.

[0113] To meet the strength requirements of high-speed motors, end plate 2 is made of high-strength material. In some embodiments, end plate 2 is made of aerospace-grade aluminum alloy 7075-T6, which has good thermal conductivity and high strength, to ensure the heat dissipation performance of rotor 01 while meeting the strength requirements in high-speed scenarios. End plate 2 may also be made of other forms of high-strength material, and this application does not impose specific limitations on this; those skilled in the art can selectively design according to actual needs.

[0114] Figure 6 for Figure 4 A cross-sectional view of the Sinopec refrigerated motor along line PP. (Refer to...) Figure 6 The motor shaft 03 is a hollow structure. The motor shaft 03 includes an axial flow channel 031 and multiple radial oil holes 032. Cooling oil entering the axial flow channel 031 is transported to the interior of the rotor 01 through the multiple radial oil holes 032 to cool the rotor 01.

[0115] In some embodiments, refer to Figure 6 The inner diameter of each radial oil hole 032 is smaller than the inner diameter of the axial flow channel 031 to increase the flow rate of the cooling oil entering the radial oil hole 032, ensuring that the cooling oil quickly enters the interior of the rotor 01, increasing the contact time between the cooling oil and the rotor core 1, which is beneficial to improving the heat dissipation efficiency of the rotor 01.

[0116] In some embodiments, the plurality of radial oil holes 031 comprises two sets. One set of radial oil holes 031 is used to supply cooling oil to the first end plate 2a and, through the first end plate 2a, to the interior of the rotor core 1. The other set of radial oil holes 031 is used to supply cooling oil to the second end plate 2b and, through the second end plate 2b, to the interior of the rotor core 1. The two sets of radial oil holes 031 are arranged at intervals along direction A, and each set of radial oil holes 031 is arranged at intervals along the circumference of the motor shaft 03, with the two sets of radial oil holes 031 staggered along the circumference of the rotor.

[0117] The embodiments of this application supply oil to both end plates 2 simultaneously, and the cooling oil flows bidirectionally within the rotor 01. On the one hand, this makes the temperature distribution of the rotor 01 uniform, reducing the possibility of thermal bending deformation of the rotor 01. On the other hand, it makes the overall cooling efficiency higher, so as to improve the cooling efficiency of the oil-cooled motor 10 while meeting the high-speed strength requirements, and ensure the reliability of motor operation.

[0118] In some embodiments, the motor shaft 03 is a single piece, which helps reduce the processing cost and assembly difficulty of the motor shaft 03, and also helps improve the operational reliability of the motor shaft 03. In some embodiments, Figure 2 The reducer 20 in the motor includes a planetary gear reducer. The axial end of the motor shaft 03 and the sun gear of the planetary gear reducer are integrated into a single design to form an integrated sun gear motor shaft, which has the functions of transmitting torque and cooling, thus improving the motor's transmission efficiency and cooling efficiency.

[0119] Reference Figure 5 and Figure 6 Each end plate 2 includes multiple sets of grooves 22 located on the side of the end plate 2 facing the rotor core 1. Each set of grooves 22 includes multiple grooves, which are spaced apart along the C direction. The rotor core 1 includes multiple internal flow channels 12, which include multiple sets of internal flow channels 12. The multiple sets of internal flow channels 12 are spaced apart along the C direction.

[0120] A set of internal flow channels 12 Figure 5 As shown in the dashed box Z, each set of internal flow channels 12 includes a first internal flow channel 12a and a second internal flow channel 12b. The first internal flow channel 12a is used to receive cooling oil delivered by the motor shaft 03 through a groove 22 in one end plate 2. The second internal flow channel 12b is used to discharge cooling oil through another groove 22 in one end plate 2. A groove 22 in the other end plate 2 is used to connect the first internal flow channel 12a and the second internal flow channel 12b to form a double-layer oil flow channel. Compared with the single-layer oil flow channel or the double-layer non-connected oil flow channel scheme, the double-layer oil flow channel of this application increases the flow length and time of cooling oil in the rotor core 1, which is beneficial to further improve the heat dissipation and cooling effect of the rotor core 1.

[0121] In some embodiments, multiple sets of internal flow channels 12 are evenly arranged at intervals along the C direction so that the cooling oil is uniformly transported in the inner circumference of the rotor core 1, thereby achieving uniform heat dissipation of the rotor core 1 and improving the overall heat dissipation efficiency of the rotor 01.

[0122] Reference Figure 6 In each end plate 2a, one set of grooves 22 includes multiple third grooves 22c, which are spaced apart along the C direction. Another set of grooves 22 includes multiple second grooves 22b, which are spaced apart along the C direction. A third set of grooves 22 includes multiple first grooves 22a, which are spaced apart along the C direction.

[0123] In the following text, for ease of distinction and description, another set of grooves 22 including multiple first grooves 22a will be referred to as the first set of grooves, another set of grooves 22 including multiple second grooves 22b will be referred to as the second set of grooves, and a set of grooves 22 including multiple third grooves 22c will be referred to as the third set of grooves.

[0124] Reference Figure 6 A first groove 22a and a third groove 22c of one end plate 2, a set of internal flow channels 12 of the rotor core 1, and a second groove 22b of the other end plate 2 form a cooling oil flow channel.

[0125] In the double-layer oil flow channel on the side where the first end plate 2a is located: a first groove 22a of the first end plate 2a is used to receive cooling oil supplied by a radial oil hole 032 of the motor shaft 03 and transfer the cooling oil to a first internal flow channel 12a. The cooling oil flows along the first internal flow channel 12a and enters a second internal flow channel 12b through a second groove 22b of the second end plate 2b. A third groove 22c of the first end plate 2a is used to receive the cooling oil in the second internal flow channel 12a and discharge the received cooling oil into the interior of the rotor 01.

[0126] In the double-layer oil flow channel on the side where the second end plate 2b is located: a first groove 22a of the second end plate 2b is used to receive cooling oil supplied by a radial oil hole 032 of the motor shaft 03 and transfer the cooling oil to a first internal flow channel 12a. The cooling oil flows along the first internal flow channel 12a and enters the second internal flow channel 12b through a second groove 22b of the first end plate 2a. A third groove 22c of the second end plate 2b is used to receive the cooling oil in the second internal flow channel 12a and discharge the received cooling oil into the interior of the rotor 01.

[0127] Figure 7 This is a partial structural schematic diagram of a rotor core provided in an embodiment of this application. (Refer to...) Figure 7In each group of internal flow channels 12, the first internal flow channel 12a and the second internal flow channel 12b are arranged radially at intervals along the rotor 01. The distance between the first internal flow channel 12a and the inner circumferential surface of the rotor core 1 is d1, and the distance between the second internal flow channel 12b and the inner circumferential surface of the rotor core 1 is d2, where d1 is less than d2. Therefore, the first internal flow channel 12a is located radially inside the second internal flow channel 12b.

[0128] In some embodiments, the area of ​​the first internal flow channel 12a is larger than the area of ​​the second internal flow channel 12b. The area of ​​the first internal flow channel 12a is the cross-sectional area of ​​the first internal flow channel 12a, and the area of ​​the second internal flow channel 12b is the cross-sectional area of ​​the second internal flow channel 12b.

[0129] Because the cross-sectional area of ​​the first internal flow channel 12a is large, the flow rate of the cooling oil entering the first internal flow channel 12a from the groove 22 of the end plate 2 is reduced, which helps the cooling oil to enter the first internal flow channel 12a and the second internal flow channel 12b evenly. It also increases the contact time between the cooling oil, which has just entered the rotor core 1 and is at a low temperature, and the rotor core 1, which is beneficial to improving the heat exchange efficiency.

[0130] The cross-sectional area of ​​the first internal flow channel 12a is relatively large, which makes the flow resistance in the first internal flow channel 12a smaller. Under the same conditions, the flow rate of cooling oil increases, which in turn helps to increase the heat carried away by the cooling oil per unit time.

[0131] The first internal flow channel 12a has a smaller area. When the cooling oil enters the second internal flow channel 12b with a smaller cross-section from the large-section first internal flow channel 12a, the cooling oil velocity increases. This increased velocity serves two purposes: firstly, it disrupts the oil film formed on the inner wall of the flow channel. The oil film is a relatively static layer of oil tightly adhering to the rotor core 1. Higher velocity results in a thinner oil film, lower thermal resistance, and higher heat exchange efficiency. Secondly, it enhances turbulence, thus strengthening the heat exchange between the cooling oil and the rotor core 1.

[0132] When the cooling oil flows into the second internal flow channel 12b, the temperature of the cooling oil is higher than that of the oil in the first internal flow channel 12a. Since the area of ​​the second internal flow channel 12b is smaller than that of the first internal flow channel 12a, the flow rate of the cooling oil is increased, which is beneficial to increasing the overall cooling oil flow rate.

[0133] In some embodiments, refer to Figure 7 The circumferential dimension of the first internal flow channel 12a is the dimension of the first internal flow channel 12a along the C direction, such as... Figure 7 As shown in L1. The circumferential dimension of the second internal flow channel 12b is the dimension of the second internal flow channel 12b along the C direction, as shown in... Figure 7 As shown in L2, where L1 is greater than L2.

[0134] The large circumferential dimension L1 of the first internal flow channel 12a facilitates the uniform distribution of cooling oil along the circumference of the rotor 01, preventing insufficient cooling or excessive local cooling oil flow. During high-speed rotation, centrifugal force causes the cooling oil to be thrown onto the radial inner wall of the flow channel. The wider circumferential dimension increases the contact area between the cooling oil and the radial sidewall of the flow channel, which helps to improve the heat exchange efficiency between the cooling oil and the rotor core 1 in the first internal flow channel 12a.

[0135] The smaller circumferential dimension L2 of the second internal flow channel 12b reduces internal circulation or dead zones caused by excessively wide channels, which is beneficial to improving the heat exchange efficiency between the cooling oil and the rotor core 1. On the other hand, it allows the rotor core 1 to retain more solid material in areas with high centrifugal force, improving the strength and rigidity of the rotor 01, ensuring structural stability of the rotor 01 at high speeds, and preventing deformation of the rotor 01 due to excessive centrifugal force.

[0136] In some embodiments, refer to Figure 7 The radial dimension of the first internal flow channel 12a is the dimension of the first internal flow channel 12a along the B direction, such as... Figure 7 As shown in K1. The radial dimension of the second internal flow channel 12b is the dimension of the second internal flow channel 12b along the B direction, as shown in K1. Figure 7 As shown in K2, where K2 is less than K1.

[0137] The large radial dimension K1 of the first internal flow channel 12a helps to reduce the cooling oil flow rate, thus playing a role in oil buffering and flow stabilization. When the rotor 01 rotates at high speed, the centrifugal force on the cooling oil increases, and the larger radial dimension provides a radial flow path for the cooling oil, thereby playing a role in flow field guidance.

[0138] The small radial dimension K2 of the second internal flow channel 12b limits the thickness of the oil film between the cooling oil and the inner wall of the flow channel, thereby improving heat transfer efficiency. Furthermore, it restricts the internal circulation of the cooling oil, ensuring contact between the oil and the inner wall of the second internal flow channel 12b, further enhancing the heat dissipation of the rotor 01.

[0139] In some embodiments, refer to Figure 7 The spacing between the first internal flow channel 12a and the second internal flow channel 12b is the spacing between the first internal flow channel 12a and the second internal flow channel 12b along direction B, as shown in the figure. Figure 7 As shown in d3. Among them, K2 is greater than d3, and K1 is greater than d3.

[0140] Along direction B, d3 is minimized, so that the first internal flow channel 12a and the second internal flow channel 12b are arranged radially compactly. After the cooling oil leaves the first internal flow channel 12a, it quickly enters the second internal flow channel 12b under the action of stronger centrifugal force, so as to limit the eddies or dead zones that may be generated between the first internal flow channel 12a and the second internal flow channel 12b, thereby enhancing heat dissipation.

[0141] Figure 8 This is one of the three-dimensional structural diagrams of a rotor end plate provided in the embodiments of this application. Figure 9 This is a second perspective structural diagram of a rotor end plate provided in an embodiment of this application. (Refer to...) Figure 8 and Figure 9 The multiple sets of grooves 22 of each end plate 2 are spaced differently from the outer peripheral surface of the end plate 2, so as to cover the flow channels of the rotor core 1 at different radial positions through the multiple sets of grooves 22.

[0142] Reference Figure 6 and Figure 8 In the multiple sets of grooves, the three first grooves 22a of the first set of grooves are evenly spaced along the C direction, the three second grooves 22b of the second set of grooves are evenly spaced along the C direction, and the three third grooves 22c of the third set of grooves are evenly spaced along the C direction.

[0143] Each first groove 22a in the first group of grooves and a corresponding third groove 22c in the third group of grooves are arranged radially at intervals along the rotor 01. A second groove 22b is distributed between two adjacent first grooves 22a along the C direction. The projection of the second groove 22b along the C direction overlaps with the first groove 22a and the third groove 22c, respectively, so as to form a double-layer oil channel through the first groove 22a, the second groove 22b, the third groove 22c and the internal flow channel 12 of the rotor core 1.

[0144] Reference Figure 6 and Figure 8 The end plate 2 includes multiple oil outlet holes 23, each of which penetrates the end plate 2 along direction A, and the multiple oil outlet holes 23 are spaced apart along direction C. The oil outlet holes 23 are used to discharge the cooling oil inside the rotor 01.

[0145] In some embodiments, one end of the oil outlet 23 is located at the bottom of the third groove 22c, and the oil entering the third groove 22c is discharged from the rotor 01 through the oil outlet 23. As the cooling oil is thrown to the side of the third groove 22c near the outer peripheral surface of the end plate 2 under the action of centrifugal force, and the oil outlet 23 is located on the side of the third groove 22c near the outer peripheral surface of the end plate 2, it is convenient for the cooling oil to flow out quickly from the oil outlet 23, reducing the eddies or dead zones that may be generated between the third grooves 22c, and reducing the flow time of the cooling oil in the end plate 2, thereby helping to enhance heat dissipation.

[0146] The above embodiment describes the arrangement of multiple grooves 22 in the end plate 2 as an example when the internal flow channel 12 of the rotor core 1 is a double-layer flow channel. In other embodiments of this application, when the internal flow channel 12 of the rotor core 1 is a three-layer or more flow channel, the number and arrangement of multiple grooves 22 in the end plate 2 can be selectively adjusted according to actual needs.

[0147] Below, this application will take the internal flow channel 12 of the rotor core 1 as an example of a double-layer flow channel, and further describe in detail the specific form of the three sets of grooves 22 on the end plate 2.

[0148] Figure 10 This is a schematic diagram of a rotor end plate provided in an embodiment of this application. (Refer to...) Figure 10 The distances between the multiple sets of grooves 22 and the outer peripheral surface of the end plate 2 are not equal.

[0149] The distance between the first set of grooves and the outer peripheral surface of the end plate 2 is d4. The distance between the second set of grooves and the outer peripheral surface of the end plate 2 is d5. The distance between the third set of grooves and the outer peripheral surface of the end plate 2 is d6. The values ​​of d4, d5, and d6 are not equal, so that multiple sets of grooves 22 connect with the internal flow channels 12 in different radial regions of the rotor core 1, forming a double-layer oil channel. Under the action of centrifugal force, the cooling oil flows to different positions in the radial direction of the rotor core 1 to remove heat from different positions of the rotor core 1, thereby improving the cooling effect of the rotor 01.

[0150] In some embodiments, the distance between the first group of grooves and the outer peripheral surface of the end plate 2 is greater than the distance between the other groups of grooves and the outer peripheral surface of the end plate 2. (Refer to...) Figure 10 d4 is greater than d5, and d4 is greater than d6. The first set of grooves along the radial direction of rotor 01 is located at the innermost side of the second and third sets of grooves.

[0151] The first set of grooves includes a plurality of first grooves 22a, which are evenly distributed along the C-direction. A portion of each first groove 22a is used to receive cooling oil supplied by the motor shaft 03 of the oil-cooled motor 10. Another portion of each first groove 22a is used to supply cooling oil to a first internal flow channel 12 of the rotor core 1. In other embodiments of this application, another portion of the first groove 22a is used to supply cooling oil to a plurality of first internal flow channels 12 of the rotor core 1. Those skilled in the art can selectively design according to actual needs.

[0152] A portion of the first groove 22a, as shown Figure 10 The letter a1 indicates that the other part of the first groove 22a is as follows: Figure 10 The letter a2 in the middle refers to.

[0153] In some embodiments, the radial dimension of a portion a1 of the first groove 22a refers to the radial dimension of a portion a1 of the first groove 22a along the rotor O1, such as... Figure 10 As shown in K3. The radial dimension of the other part a2 of the first groove 22a refers to the radial dimension of the other part a2 of the first groove 22a along the rotor O1, as shown in K3. Figure 10 As shown in K4, where K3 is greater than K4.

[0154] The circumferential dimension of a portion a1 of the first groove 22a refers to the dimension of a portion a1 of the first groove 22a along the C direction, such as... Figure 10 As shown in L3. The circumferential dimension of the other part a2 of the first groove 22a refers to the dimension of the other part a2 of the first groove 22a along the C direction, as shown in... Figure 10 As shown in L4, where L4 is greater than L3.

[0155] The cooling oil delivered by the motor shaft 03 enters the corresponding first groove 22a through a portion a1 of each first groove 22a in the first set of grooves, and supplies oil to at least one internal flow channel 12 of the rotor core 1 through another portion a2 of the first groove 22a.

[0156] The radial dimension K3 of a portion a1 of the first groove 22a is large, and the circumferential dimension L3 is large, so as to increase the flow rate of the cooling oil in the portion a1 of the first groove 22a, ensuring that the cooling oil quickly enters the other portion a2 of the first groove 22a, shortening the flow length and flow time of the cooling oil in the radial direction of the first groove 22a. Under the same flow rate, the flow length and flow time of the cooling oil on the end plate 2 are reduced, which increases the flow time of the cooling oil in the rotor core 1, increases the heat exchange time between the cooling oil and the rotor 01, and is beneficial to improving the cooling efficiency of the rotor 01.

[0157] L4 is greater than L3, so as to reduce the flow rate of the cooling oil entering the other part a2 of the first groove 22a and play a role in stabilizing the pressure, thereby reducing the flow rate of the oil entering the first internal flow channel 12 of the rotor core 1. The oil flows slowly in the first internal flow channel 12, and the heat exchange time increases, which is conducive to improving the heat exchange efficiency between the cooling oil and the rotor core 1.

[0158] In some embodiments, the radial dimension K4 of another portion a2 of the first groove 22a is smaller than the circumferential dimension L3 of a portion a1 of the first groove 22a.

[0159] By limiting the radial dimension K4 of another portion a2 of the first groove 22a, the radial space occupied by the first groove 22a is reduced, which facilitates the compact radial arrangement of multiple sets of grooves 22. The small total radial length of the first groove 22a also shortens the length and time of the cooling oil flow in the first groove 22a. At the same flow rate, the reduced flow length and time of the cooling oil on the end plate 2 increases the flow time of the cooling oil in the rotor core 1, thereby increasing the heat exchange time between the cooling oil and the rotor 01 and improving the cooling efficiency of the rotor 01.

[0160] In some embodiments, each second groove 22b in the second set of grooves is used to connect at least two internal flow channels 12 of the rotor core 1. (Refer to...) Figure 6 The second groove 22b is used to connect a first internal flow channel 12a and a second internal flow channel 12b of the rotor core 1. Different second grooves 22b connect to different internal flow channels 12.

[0161] Reference Figure 10 The distance between the second set of grooves and the inner circumferential surface of end plate 2 is d7, and the distance between the first set of grooves and the inner circumferential surface of end plate 2 is d8. Wherein, d7 is less than d8. The second set of grooves and the first set of grooves are arranged in a staggered manner along the radial direction of rotor 01, with the second set of grooves closer to the inner circumferential surface of end plate 2.

[0162] In some embodiments, the circumferential dimension of the second groove 22b is greater than the radial dimension of the second groove 22b. (Refer to...) Figure 10 The circumferential dimension of the second groove 22b is L5, and the radial dimension of the second groove 22b is K5. Wherein, L5 is greater than K5.

[0163] By limiting the radial dimension of the second groove 22b, the space occupied by the second groove 22b in the radial direction is reduced, which facilitates the compact radial arrangement of multiple sets of grooves 22. The small radial dimension of the second groove 22b also shortens the flow length and time of the cooling oil in the radial direction of the second groove 22b. Under the same flow rate, the flow length and flow time of the cooling oil on the end plate 2 are reduced, which increases the flow time of the cooling oil in the rotor core 1, increases the heat exchange time between the cooling oil and the rotor 01, and helps to improve the cooling efficiency of the rotor 01.

[0164] In some embodiments, refer to Figure 10The second groove 22b includes multiple groove segments 221. These multiple groove segments 221 include a first groove segment 2211, a second groove segment 2212, and a third groove segment 2213. The first groove segment 2211, the second groove segment 2212, and the third groove segment 2213 are arranged sequentially along the radial direction of the rotor 01. The distance between the first groove segment 2211 and the inner circumferential surface of the end plate 2 is less than the distance between the third groove segment 2213 and the inner circumferential surface of the end plate 2; therefore, the first groove segment 2211 is located radially inside the third groove segment 2213. The first groove segment 2211 and the third groove segment 2213 are respectively used to connect different internal flow channels 12.

[0165] The area of ​​the third segment 2213 is greater than the area of ​​the second segment 2212 but less than the area of ​​the first segment 2211.

[0166] The area of ​​the first slot 2211 is larger than the areas of the second slot 2212 and the third slot 2213, which limits the overall flow rate of cooling oil from the first slot 2211 to the third slot 2213 per unit time. This reduces the flow rate of cooling oil from the internal flow channel 12 of the rotor core 1 to the first slot 2211, ensuring the flow time of the cooling oil in the internal flow channel 12, and thus improving the heat dissipation efficiency of the rotor 01.

[0167] The area of ​​the third groove 2213 is larger than that of the second groove 2212, which reduces the flow rate of the cooling oil entering the third groove 2213 from the second groove 2212. This reduces the flow rate of the oil entering the internal flow channel 12, which on the one hand helps the cooling oil to enter the internal flow channel 12 of the rotor core 1 more evenly, and on the other hand helps to increase the heat exchange time between the cooling oil and the rotor core 1.

[0168] In addition, the second groove section 2212 has the smallest area. When the cooling oil is transported from the first groove section 2211 to the second groove section 2212, the flow rate increases sharply and it quickly enters the second groove section 2212, thereby reducing the flow time of the cooling oil in the second groove section 2212. This helps to increase the heat exchange time between the cooling oil in the rotor core 1 and the rotor core 1.

[0169] In some embodiments, the circumferential dimension of the third slot segment 2213 is greater than the circumferential dimension of the second slot segment 2212 and less than the circumferential dimension of the first slot segment 2211. The circumferential dimension refers to the dimension along the circumference of the rotor 01.

[0170] Reference Figure 10The circumferential dimension of the first slot segment 2211 is L5. The circumferential dimension of the second slot segment 2212 is L6. The circumferential dimension of the third slot segment 2213 is L7. L6 < L7 < L5. The circumferential dimension L5 of the first slot segment 2211 is the largest, which ensures that the cooling oil entering the first slot segment 2211 from the first internal flow channel 12a of the rotor core 1 is evenly distributed within the circumferential range of the first slot segment 2211, and reduces the flow rate of the cooling oil, thus playing a role in stabilizing the pressure.

[0171] The second groove section 2212 has the smallest circumferential dimension L6. On the one hand, it is used to control the flow rate of cooling oil from the first groove section 2211 to the third groove section 2213. On the other hand, it is used to increase the flow rate of cooling oil so that the cooling oil can quickly enter the third groove section 2213 and reduce the flow time of cooling oil in the second groove section 2212.

[0172] The circumferential dimension L7 of the third slot 2213 is centered, and the flow rate of the cooling oil entering the third slot 2213 from the second slot 2212 is reduced, which helps the cooling oil to enter the second internal flow channel 12b of the rotor core 1 more evenly.

[0173] In some embodiments, the radial dimension of the second slot segment 2212 is greater than the radial dimension of the third slot segment 2213 and less than the radial dimension of the first slot segment 2211. The radial dimension refers to the dimension along the radial direction of the rotor 01.

[0174] Reference Figure 10 The radial dimension of the first groove segment 2211 is K6. The radial dimension of the third groove segment 2213 is K7. The radial dimension of the second groove segment 2212 is the difference between the sum of K6 and K7 and K5. K7 < radial dimension of the second groove segment 2212 < K6.

[0175] The first groove section 2211 has the largest radial dimension K6, which provides a larger radial path for the cooling oil entering the first groove section 2211, ensuring that the cooling oil obtains greater kinetic energy and provides greater driving force for the subsequent flow of cooling oil.

[0176] Since the circumferential dimension L6 of the second slot segment 2212 is the smallest, the radial dimension of the second slot segment 2212 is greater than the radial dimension K7 of the third slot segment 2213 and less than the radial dimension K6 of the second slot segment 2212. This enhances the structural strength of the second slot segment 2212 and ensures that the second slot segment 2212 still has sufficient rigidity and strength under high-speed rotation, thereby ensuring the safe operation of the rotor 01.

[0177] The radial dimension K7 of the third groove section 2213 is the smallest. On the one hand, this allows the cooling oil to flow radially along the end plate 2 within the third groove section 2213, limiting the generation of axial eddies and other vortices in the cooling oil, and ensuring that the cooling oil in the third groove 22c enters the internal flow channel 12 of the rotor core 1 quickly and accurately. On the other hand, it ensures the area of ​​the solid portion of the outer circumference of the end plate 2, improving the structural strength and rigidity of the end plate 2, and preventing deformation or tearing of the end plate 2 under high-speed rotation.

[0178] In some embodiments, the radial dimension of each slot segment 221 is smaller than its circumferential dimension. (Refer to...) Figure 10 The radial dimension K6 of the first groove segment 2211 is smaller than the circumferential dimension L5 of the first groove segment 2211, the radial dimension of the second groove segment 2212 is smaller than the circumferential dimension L6 of the second groove segment 2212, and the radial dimension K7 of the third groove segment 2213 is smaller than the circumferential dimension L7 of the third groove segment 2213.

[0179] By limiting the radial dimension of each groove segment 221, the radial space occupied by the second set of grooves is reduced, which facilitates a compact radial arrangement of multiple sets of grooves 22. The small radial dimension of the second groove 22b also shortens the flow length and time of the cooling oil in the radial direction. At the same flow rate, the reduced flow length and time of the cooling oil on the end plate 2 increases the flow time of the cooling oil within the rotor core 1, thereby increasing the heat exchange time between the cooling oil and the rotor 01 and improving the cooling efficiency of the rotor 01.

[0180] In the above embodiments, the first channel segment 2211 is connected to a first internal flow channel 12a, and the third channel segment 2213 is connected to a second internal flow channel 12b. In other embodiments of this application, the first channel segment 2211 is connected to multiple internal flow channels, and the third channel segment 2213 is connected to multiple internal flow channels to deliver cooling oil to multiple internal flow channels. Those skilled in the art can selectively design according to actual needs.

[0181] In some embodiments, the distance between the third set of grooves and the outer peripheral surface of the end plate 2 is smaller than the distance between the other sets of grooves and the outer peripheral surface of the end plate 2. The third set of grooves is the set of grooves 22 closest to the outer peripheral surface of the end plate 2. Each third groove 22c in the third set of grooves is used to receive oil from at least one internal flow channel 12 of the rotor core 1 and to discharge cooling oil from inside the rotor 01.

[0182] Reference Figure 6 and Figure 10 Each third groove 22c is used to connect a second internal flow channel 12b of the rotor core 1 and an oil outlet 23 to receive oil from the second internal flow channel 12b of the rotor core 1 and discharge cooling oil through the oil outlet 23. The internal flow channel 12 and oil outlet 23 connected to different third grooves 22c are all different.

[0183] In the embodiments of this application, the radial dimension of each third groove 22c in the third group of grooves is smaller than the radial dimension of each groove 22 in the other groups of grooves. The circumferential dimension of each third groove 22c in the third group of grooves is smaller than the circumferential dimension of each groove 22 in the other groups of grooves.

[0184] Reference Figure 10 The radial dimension of the third groove 22c is smaller than the radial dimension of the second groove 22b and the radial dimension of the first groove 22a. The circumferential dimension of the third groove 22c is smaller than the circumferential dimension of the second groove 22b and the circumferential dimension of the first groove 22a.

[0185] In the embodiments of this application, the radial dimension and circumferential dimension of the third groove 22c are minimized to limit the flow rate of cooling oil flowing out of the rotor 01 per unit time, thereby increasing the flow time of cooling oil in the rotor core 1 and increasing the heat exchange time between the cooling oil and the rotor core 1. This is beneficial to improving the cooling efficiency of the rotor 01 and ensuring the operational reliability of the oil-cooled motor 10.

[0186] In some embodiments, the distance between the third groove 22c and the outer peripheral surface of the end plate 2 is d6, and the distance between the third groove 22c and the inner peripheral surface of the end plate 2 is d8. d6 is greater than d8, so the third groove 22c is closer to the inner peripheral surface of the end plate 2, so that multiple sets of grooves 22 are generally close to the inner peripheral surface of the end plate 2 and are arranged compactly along the radial direction of the end plate 2.

[0187] Compared to the scheme where multiple sets of grooves 22 are radially dispersed on the end plate 2, this application uses multiple sets of grooves 22 close to the inner circumferential surface of the end plate 2 and arranges them compactly in the radial direction of the end plate 2, thereby reducing the resistance of the cooling oil in the flow channel. Under the same conditions, the reduced resistance of the cooling oil in the flow channel is beneficial to increasing the flow rate of the cooling oil, which in turn is beneficial to increasing the heat carried away by the cooling oil per unit time, and thus improving the heat dissipation of the rotor 01.

[0188] Furthermore, the multiple sets of grooves 22 are arranged compactly near the inner circumferential surface of the end plate 2, which reduces the flow length and flow time of the cooling oil on the end plate 2. Under the same flow rate, the flow length and flow time of the cooling oil on the end plate 2 are reduced, which increases the flow time of the cooling oil in the rotor core 1 and increases the heat exchange time between the cooling oil and the rotor 01, thereby improving the cooling efficiency of the rotor 01.

[0189] In some embodiments, a portion of the third groove 22c is used to connect to at least one internal flow channel 12. The bottom of another portion of the third groove 22c includes an oil outlet 23. The oil outlet 23 extends through the end plate 2 along the axial direction of the rotor 01.

[0190] Reference Figure 6 andFigure 10 A portion of the third groove 22c is used to connect to a second internal flow channel 12b. A portion of the third groove 22c is indicated by a3, and another portion of the third groove 22c is indicated by a4. The distance between the portion a3 of the third groove 22c and the inner circumferential surface of the end plate 2 is d8, which is smaller than the distance between the oil outlet 23 and the inner circumferential surface of the end plate 2.

[0191] During the operation of rotor 01, the cooling oil in the third groove 22c is thrown onto the side wall near the outer peripheral surface of end plate 2 under the action of centrifugal force. In order to facilitate the cooling oil to be thrown out of end plate 2, oil outlet holes 23 are arranged at the bottom of the groove of another part a4 of the third groove 22c, and the oil outlet holes 23 are distributed on the side of the other part a4 of the third groove 22c near the outer peripheral surface of end plate 2. This ensures that the cooling oil is quickly discharged from the oil outlet holes 23. On the one hand, it reduces the flow time of the cooling oil in end plate 2, and on the other hand, it reduces the possibility of eddies or dead zones generated by the cooling oil in the third groove 22c, thereby helping to enhance the heat dissipation effect of rotor 01.

[0192] In other embodiments of this application, a portion of the third groove 22c is used to connect multiple internal flow channels to deliver cooling oil to the multiple internal flow channels. Those skilled in the art can selectively design this according to actual needs.

[0193] In some embodiments, the circumferential dimension of a portion a3 of the third groove 22c is L8, and the circumferential dimension of another portion a4 of the third groove 22c is L9. L9 is less than L8, and L9 is greater than the diameter of the oil outlet hole 23.

[0194] Since a portion a3 of the third groove 22c is used to connect with at least one internal flow channel 12 of the rotor core 1, and another portion a4 is used to discharge cooling oil, by limiting L9 to be less than L8, the flow rate of cooling oil flowing through the other portion a4 of the third groove 22c per unit time is reduced during the process of cooling oil flowing from a portion a3 of the third groove 22c to a portion a4 of the third groove 22c, so as to prolong the flow time of cooling oil in the rotor core 1, the heat exchange time between cooling oil and rotor 01 is increased, which is beneficial to improving the cooling efficiency of rotor 01.

[0195] By limiting L9 to be larger than the diameter of the oil outlet hole 23, the flow rate of cooling oil flowing through the oil outlet hole per unit time is reduced during the process of cooling oil flowing from the other part a4 of the third groove 22c to the oil outlet hole 23. This helps to extend the flow time of cooling oil in the rotor core 1, thereby improving the cooling efficiency of the rotor 01.

[0196] In some embodiments, the radial dimension of a portion a3 of the third groove 22c is K8, and the distance between a portion a3 of the third groove 22c and the oil outlet hole 23 is K9. K8 is smaller than the diameter of the oil outlet hole 23, and K8 is greater than K9.

[0197] By limiting the radial dimension K8 of a portion a3 of the third groove 22c and the distance K9 between a portion a3 of the third groove 22c and the oil outlet 23, the radial space occupied by the third groove 22c is reduced, which facilitates the compact radial arrangement of multiple sets of grooves 22. The small radial dimension of the third groove 22c also shortens the flow length and time of the cooling oil in the radial direction. Under the same flow rate, the reduced flow length and time of the cooling oil on the end plate 2 increases the flow time of the cooling oil in the rotor core 1, thereby increasing the heat exchange time between the cooling oil and the rotor 01 and improving the cooling efficiency of the rotor 01.

[0198] Reference Figure 10 The end plate 2 includes multiple through holes 24, which are arranged at intervals along the circumference of the rotor 01. The through holes 24 penetrate the end plate 2 along the axial direction of the rotor 01. The multiple through holes 24 on the plate serve to reduce weight and achieve dynamic balance of the rotor 01.

[0199] In some embodiments, a through hole 24 is distributed between adjacent second grooves 22b and third grooves 22c. The angle between the through hole 24 and the second groove 22b is the same as the angle between the through hole 24 and the third groove 22c. Where P is the number of pole pairs of the oil-cooled motor 10.

[0200] Figure 11 This is a schematic diagram of the structure of a rotor 01 provided in an embodiment of this application. (Refer to...) Figure 11 The rotor core 1 includes a plurality of magnet slots 13. Each magnet slot 13 is used to accommodate at least one magnet 3. Along the axial direction of the rotor 01, each through hole 24 is opposite to a portion of at least one magnet slot 13, so that a portion of the heat of the magnet 3 in the magnet slot 13 is dissipated along the through hole 24 to the outside of the rotor 01, thereby improving the heat dissipation effect of the rotor 01.

[0201] In some embodiments, refer to Figure 10 and Figure 11 The distance between the through hole 24 and the outer peripheral surface of the end plate 2 is d10, and the distance between the through hole 24 and the inner peripheral surface of the end plate 2 is d11. d10 is greater than the distance d6 between the third groove 22c and the outer peripheral surface of the end plate 2. d11 is less than the distance between a set of grooves 22 and the inner peripheral surface of the end plate 2.

[0202] The through holes 24 are arranged radially offset from the third groove 22c and the second groove 22b of the rotor 01, respectively. While ensuring the strength and rigidity of the end plate 2, the magnet slot 13 is close to the internal flow channel 12 of the rotor core 1 connected by the third groove 22c, so as to improve the heat dissipation efficiency of the rotor 01.

[0203] In some embodiments, the axial dimension of the through hole 24 is greater than the radial dimension of the through hole 24 and the circumferential dimension of the groove 22, so that the circumferential coverage of the through hole 24 is larger, which is beneficial to increasing the relative area between the magnet groove 13 and the through hole 24, thereby improving heat dissipation.

[0204] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An oil-cooled electric machine characterized by, The rotor of the oil-cooled motor comprises a rotor core and an end plate, the end plate comprises a plurality of groups of grooves, the plurality of groups of grooves are located on the side of the end plate facing the rotor core, the plurality of groups of grooves are respectively not equal in distance from the outer circumferential surface of the end plate, wherein: Each groove in one group of grooves in the plurality of groups of grooves is used for receiving oil liquid of at least one internal flow channel of the rotor core and for discharging cooling oil in the interior of the rotor; The radial dimension of each groove in the one group of grooves is smaller than the radial dimension of each groove in other groups of grooves, and the circumferential dimension of each groove in the one group of grooves is smaller than the circumferential dimension of each groove in other groups of grooves.

2. The oil-cooled electric machine of claim 1, wherein, The distance from the one group of grooves to the outer circumferential surface of the end plate is smaller than the distance from other groups of grooves to the outer circumferential surface of the end plate, wherein: The distance from each groove in the one group of grooves to the outer circumferential surface of the end plate is greater than the distance from each groove in the one group of grooves to the inner circumferential surface of the end plate.

3. The oil-cooled electric machine of claim 1 or 2, wherein, A part of each groove in the one group of grooves is used for communicating at least one internal flow channel, the bottom of another part of each groove in the one group of grooves comprises an oil outlet hole, the oil outlet hole penetrates the end plate along the axial direction of the rotor, the distance from the part of each groove in the one group of grooves to the inner circumferential surface of the end plate is smaller than the distance from the oil outlet hole to the inner circumferential surface of the end plate, wherein: The circumferential dimension of the other part of each groove in the one group of grooves is smaller than the circumferential dimension of the part of each groove in the one group of grooves and greater than the hole diameter of the oil outlet hole.

4. The oil-cooled electric machine of claim 3, wherein, The radial dimension of the part of each groove in the one group of grooves is smaller than the hole diameter of the oil outlet hole and greater than the distance from the part of each groove in the one group of grooves to the oil outlet hole.

5. The oil-cooled electric machine of any of claims 1-4, wherein, The distance from another group of grooves in the plurality of groups of grooves to the inner circumferential surface of the end plate is smaller than the distance from the one group of grooves to the inner circumferential surface of the end plate, and each groove in the another group of grooves is used for communicating at least two internal flow channels of the rotor core, wherein: The circumferential dimension of each groove in the another group of grooves is greater than the radial dimension of each groove in the another group of grooves.

6. The oil-cooled electric machine of claim 5, wherein, Each groove in the another group of grooves comprises a plurality of groove segments, the plurality of groove segments comprise a first groove segment, a second groove segment and a third groove segment, the first groove segment, the second groove segment and the third groove segment are arranged in sequence along the radial direction of the rotor, the distance from the first groove segment to the inner circumferential surface of the end plate is smaller than the distance from the third groove segment to the inner circumferential surface of the end plate, and the first groove segment and the third groove segment are respectively used for connecting different internal flow channels, wherein: The area of the third groove segment is greater than the area of the second groove segment and smaller than the area of the first groove segment.

7. The oil-cooled electric machine of claim 6, wherein, The circumferential dimension of the third groove segment is greater than the circumferential dimension of the second groove segment and smaller than the circumferential dimension of the first groove segment. The radial dimension of the second groove segment is greater than the radial dimension of the third groove segment and smaller than the radial dimension of the first groove segment.

8. The oil-cooled electric machine of claim 6 or 7, wherein, The radial dimension of each groove segment is smaller than the circumferential dimension of itself.

9. The oil-cooled electric machine of any of claims 1-8, wherein, Another one of the plurality of groups of grooves has a larger distance from the outer circumferential surface of the end plate than the other groups of grooves, a portion of each groove in the other group of grooves is configured to receive the cooling oil delivered by the motor shaft of the oil-cooled motor, and another portion of each groove in the other group of grooves is configured to deliver the cooling oil to at least one internal flow channel of the rotor core. The radial dimension of the portion of each groove in the other group of grooves is larger than the radial dimension of the other portion of each groove in the other group of grooves. The circumferential dimension of the portion of each groove in the other group of grooves is smaller than the circumferential dimension of the other portion of each groove in the other group of grooves.

10. The oil-cooled electric machine of claim 9, wherein, The radial dimension of the other portion of each groove in the other group of grooves is smaller than the circumferential dimension of the portion of each groove in the other group of grooves.

11. The oil-cooled electric machine of any of claims 1-10, wherein, The plurality of internal flow channels includes a plurality of groups of internal flow channels, the plurality of groups of internal flow channels are arranged along the circumferential direction of the rotor, each group of internal flow channels includes a first internal flow channel and a second internal flow channel, the first internal flow channel and the second internal flow channel in each group of internal flow channels are arranged along the radial direction of the rotor, the first internal flow channel is configured to receive the cooling oil delivered by the motor shaft of the oil-cooled motor through one groove, and the second internal flow channel is configured to discharge the cooling oil through another groove, wherein: The first internal flow channel has a smaller distance from the inner circumferential surface of the rotor core than the second internal flow channel, and the first internal flow channel has a larger area than the second internal flow channel.

12. The oil-cooled electric machine of claim 11, wherein, The circumferential dimension of the first internal flow channel is larger than the circumferential dimension of the second internal flow channel. The radial dimension of the second internal flow channel is smaller than the radial dimension of the first internal flow channel and larger than the distance between the first internal flow channel and the second internal flow channel.

13. The oil-cooled electric machine of any one of claims 1-12, wherein, The rotor core includes a plurality of magnetic steel grooves, each of the magnetic steel grooves is configured to accommodate at least one magnetic steel, the end plate includes a plurality of through holes, the plurality of through holes are arranged along the circumferential direction of the rotor, the through holes penetrate the end plate along the axial direction of the rotor, and each of the through holes is opposite to a portion of at least one of the magnetic steel grooves along the axial direction of the rotor, wherein: The through holes have a larger distance from the outer circumferential surface of the end plate than the group of grooves, and the through holes have a smaller distance from the inner circumferential surface of the end plate than the group of grooves.

14. A powertrain, characterized by, The power assembly includes a reducer and the oil-cooled motor according to any one of claims 1-13, and the oil-cooled motor is configured to drive the wheels of the electric vehicle through the reducer.

15. An electric vehicle characterized by comprising: The electric vehicle includes wheels and the power assembly according to claim 14, and the power assembly is configured to drive the wheels.

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