Stator assembly and motor

Abstract

The invention relates to a stator assembly for an electric machine and the electric machine itself. The stator assembly (100) comprises a stator core (20) and a winding (10), the stator core (20) is cylindrical as a whole and is provided with a plurality of groove parts (21) on the radial inner side surface, the winding (10) comprises a first conductor (11) and a second conductor (12), the first conductor (11) and the second conductor (12) are arranged in the groove parts (21) at least partially in a two-layer arrangement mode, and the first conductor (11) and the second conductor (12) are arranged in a two-layer arrangement mode. The first conductor (11) is configured as a solid conductor, the second conductor (12) is internally configured with a channel (121) penetrating along the extending direction of the second conductor (12), the first conductor (11) is arranged at the groove bottom of the groove part (21), and the second conductor (12) is arranged at the groove opening (21b) of the groove part (21). The motor comprises the above stator assembly (100).

Description

Stator assembly and motor Technical Field

[0001] The present invention relates to the technical field of electric motors, and in particular to a stator assembly for an electric motor and the electric motor itself. Background Art

[0002] In current electric motors, especially those used to provide electric driving force for pure electric vehicles or hybrid vehicles, a cooling solution for forced temperature reduction needs to be configured for the windings to ensure normal operation of the motor.

[0003] Indirect cooling is currently the most common method used in the market for cooling the stator assembly in electric motors. This is primarily achieved by installing a cooling water jacket on the outer periphery of the stator assembly. In this case, heat dissipation in the stator assembly proceeds as follows: heat generated by the winding conductors is first transferred to the stator core via the insulating paper surrounding them, then from the stator core to the aluminum shell of the cooling water jacket, and finally carried away from the jacket by the coolant in the jacket.

[0004] Different from the indirect cooling method described above, a direct cooling method can also be used. In a direct cooling solution, the winding conductor is replaced with a hollow conductor, and an insulating coolant can flow inside the hollow conductor, thereby being able to directly remove the heat generated by the winding conductor from the stator winding. This type of solution is shown, for example, in German patent publication DE102019112389A1. In another direct cooling solution, grooves can be provided on the outer surface of the winding conductor, so that after the winding is stacked, different winding conductor sections can jointly form a cooling channel for the insulating coolant to flow, in which case the coolant can also directly remove the heat generated by the winding conductor from the stator winding. This type of solution is shown, for example, in Chinese patent publication CN111463942B.

[0005] However, direct cooling solutions rely on specially constructed winding conductors, significantly increasing costs compared to conventional winding conductors. While indirect cooling methods can maintain relatively low costs by using conventional solid conductors, their cooling efficiency often falls short of the requirements of pure electric and hybrid vehicles due to the long cooling paths.

[0006] Summary of the Invention

[0007] Therefore, an object of the present invention is to provide a cooling solution for a stator assembly of an electric motor, which can provide sufficient cooling efficiency so that the electric motor can provide driving force for a pure electric vehicle or a hybrid vehicle, while ensuring acceptable manufacturing costs.

[0008] According to one aspect of the present invention, the above-mentioned object can be achieved by a stator assembly for an electric motor. The stator assembly includes a stator core and a winding, wherein the stator core is generally cylindrical and has a plurality of slots configured on its radially inner surface. The winding includes a first conductor and a second conductor, the first and second conductors being at least partially arranged in at least two layers within the slots. The first conductor is a solid conductor, and the second conductor has a channel configured therein extending along its extension direction. The first conductor is arranged at the bottom of the slot, and the second conductor is arranged at the slot opening.

[0009] Here, the stator assembly is cylindrical as a whole and can be particularly used for an inner rotor type rotating motor. In this case, after the motor is assembled, the rotor assembly of the motor can be arranged radially inside the stator assembly. It should be noted that in the description herein, unless otherwise clearly specified and defined, the terms "axial", "radial" and "circumferential direction" are all based on the central axis of the stator assembly. Specifically, "axial" is the extension direction of the central axis of the stator assembly or the direction extending parallel to the central axis; "radial" is the direction perpendicular to the central axis of the stator assembly and intersecting with the central axis; "circumferential direction" is the direction around the central axis of the stator assembly.

[0010] The winding described herein comprises a solid first conductor and a hollow second conductor. Each of the first and second conductors has a straight section arranged within a slot in the stator core and an end section extending axially beyond the slot. The first and second conductors are electrically connected in a predetermined manner outside the axial ends of the stator core, either directly via the end sections or indirectly via additional components, such as connectors, to form a complete winding coil. The winding's stacking configuration is not specified herein; it can be configured, for example, as a wave winding or a stacked winding. The phrase "the first and second conductors are at least partially arranged in at least two layers within the slots" should be understood to mean that the straight sections of the first and second conductors are stacked within each slot so that the straight sections of the different conductors are arranged radially in at least two layers. Through-holes in the second conductor allow for the flow of an insulating coolant, such as cooling oil. To this end, the coolant channel inlet and outlet are formed at the winding ends. Those skilled in the art will appreciate that this requires the provision of necessary fluid transport devices, such as pumps and other associated equipment.

[0011] By arranging a hollow second conductor at the slot opening, radially inward of the stator assembly, and a solid first conductor at the slot bottom, radially outward of the stator assembly, the cooling medium flowing within the second conductor can directly remove heat from the slot opening, where power loss is greatest, during motor operation. This effectively achieves cooling at locations with high heat dissipation requirements, thereby meeting the requirements for providing electric propulsion in pure electric or hybrid vehicles. This eliminates the need for a cooling water jacket, which has lower cooling efficiency, and eliminates the need for all conductors to be relatively expensive hollow conductors. Consequently, the stator assembly maintains cooling efficiency while also achieving lower overall cost.

[0012] In a preferred embodiment, the first and second conductors are at least partially arranged in four, six, or eight layers within the slots. In this case, the straight sections of the first and second conductors are stacked in four, six, or eight radial layers within each slot.

[0013] Here, it is particularly preferred that the two layers of conductors arranged at the slot openings serve as the second conductor. In other words, in the stator assembly, the two layers of conductors closest to the radial inside serve as the second conductor, while the conductors in the remaining layers located radially outside serve as the first conductor. The two layers of hollow conductors effectively cool windings with multiple layers of conductors.

[0014] In an advantageous embodiment, the first conductor and the second conductor are made of copper or a copper alloy material. In this case, the resistivity of the winding can be kept low and the stator copper loss can be kept low.

[0015] In an advantageous embodiment, the first conductor and the second conductor are overall U-shaped. Here, the first conductor and the second conductor are configured as U-shaped pins, also called hairpin pins, for example.

[0016] In an advantageous embodiment, the first conductor and the second conductor are linear in shape as a whole. Here, the first conductor and the second conductor are configured as I-shaped needles, for example.

[0017] In an advantageous embodiment, the first conductor and the second conductor are designed as round wires, thereby making the first conductor and the second conductor easier to manufacture.

[0018] In an advantageous embodiment, the first conductor and the second conductor are configured as flat wires, which can improve the slot fill rate of the motor, thereby allowing more conductors to be packed into the motor while maintaining the same space, generating a stronger magnetic field strength and increasing power density.

[0019] In an advantageous embodiment, the channel of the second conductor has a circular or quadrilateral cross section, thereby facilitating the production of the hollow conductor.

[0020] According to another aspect of the present invention, the above object is achieved by an electric motor, which includes a stator assembly constructed as described in the above embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The features, advantages and technical effects of the exemplary embodiments of the present invention will be described below with reference to the accompanying drawings. The accompanying drawings show:

[0022] FIG1 is a perspective view of a stator assembly according to an embodiment of the present invention;

[0023] FIG2 is a radial cross-sectional view of the stator assembly shown in FIG1 ;

[0024] FIG3 is a partial enlarged view of FIG2;

[0025] FIG4 is a perspective view of a first conductor of a winding of the stator assembly according to FIG1 ;

[0026] FIG5 is a partial perspective view of an end portion of the first conductor according to FIG4 ;

[0027] FIG6 is a perspective view of a second conductor of a winding of the stator assembly according to FIG1 ; and

[0028] FIG. 7 is a partial perspective view of an end portion of the second conductor according to FIG. 6 . DETAILED DESCRIPTION

[0029] Figure 1 shows a perspective view of a stator assembly according to one embodiment of the present invention. The stator assembly shown here is used, for example, in a permanent magnet synchronous motor. This permanent magnet synchronous motor can be used in the electric axle drive system of a pure electric vehicle or a hybrid electric vehicle. It should be understood that the permanent magnet synchronous motor also includes essential components such as a rotor assembly (not shown). In other embodiments, the motor stator assembly can also be used in other types of motors.

[0030] As shown in Figure 1, the stator assembly 100 is generally cylindrical. It includes a stator core 20 and windings 10. Accordingly, the stator core 20 is generally cylindrical. The radially inner surface of the stator core 20 is configured with a plurality of circumferentially distributed slots 21. Each slot 21 extends generally axially and opens radially inward of the stator core 20. The middle section of the winding 10 is embedded in the slots 21, forming winding ends at the axial ends of the stator core 20.

[0031] Fig. 2 shows a radial cross-sectional view of the stator assembly 100 shown in Fig. 1. Fig. 3 shows a partial enlarged view of a single slot portion 21 of the stator core 20 in Fig. 2 .

[0032] The winding 10 includes a first conductor 11 and a second conductor 12. In this embodiment, the first conductor 11 and the second conductor 12 are made of copper. FIG4 shows a perspective view of the first conductor 11 of the winding of the stator assembly 100 according to FIG1 . FIG5 shows a partial perspective view of an end portion of the first conductor 11 according to FIG4 . FIG6 shows a perspective view of the second conductor 12 of the winding 10 of the stator assembly 100 according to FIG1 . FIG7 shows a partial perspective view of an end portion of the second conductor 12 according to FIG6 .

[0033] As shown in Figures 4 and 5 , the first conductor 11 is constructed as a solid, flat hairpin. The hairpin forming the first conductor 11 is bent into a U-shape, with the first conductor 11 having two legs and a curved portion connecting the two legs. Each of the two legs has a straight section for placement within the slot 21 of the stator core 20. As shown in Figure 5 , the first conductor 11 has a substantially rectangular cross-section.

[0034] Referring to Figures 6 and 7 , the second conductor 12 is constructed as a hollow, flat hairpin. The hairpin forming the second conductor 12 is bent into a U-shape, with the second conductor 12 having two legs and a curved portion connecting the two legs. The two legs each have a straight section for placement within the slot 21 of the stator core 20. The second conductor 12 is constructed with a channel 121 extending along the direction in which the second conductor 12 extends. In this embodiment, the extension trend of the channel 121 corresponds to the overall U-shaped extension direction of the second conductor 12. Accordingly, the channel 121 located in the straight section of the second conductor 12 will be positioned in the slot 21 of the stator core 20 after the stator assembly 100 is assembled. As shown in Figure 7 , the cross-section of the second conductor 12 has a substantially rectangular outer contour, and the cross-section of the channel 121 of the second conductor 12 is also substantially rectangular.

[0035] Referring to Figures 2 and 3 , the winding 10 is constructed such that first and second conductors 11, 12 are embedded in slots 21 of the stator core 20 in a four-layer arrangement. Within each slot 21, the straight sections of the first and second conductors 11, 12 are arranged in four radially distributed layers. The solid first conductors 11 are arranged in two layers near the slot bottom 21a, i.e., in the two layers located radially outward of the stator assembly 100, while the hollow second conductors 12 are arranged in two layers near the slot opening 21b, i.e., in the two layers located radially inward of the stator assembly 100. Insulating paper 13 is interposed between the conductors 11 and 12. The free ends of the legs of the first and second conductors 11, 12 are electrically connected in a predetermined manner outside the axial ends of the stator core 20, either directly or via other components, such as connectors, to form a complete winding coil. Furthermore, cooling medium inlets and outlets are formed at the ends of the stator core 20 for the channels 121 in each second conductor 12. To this end, the free ends of the legs of the second conductors 12 also need to be fluidically connected to other components of the cooling system. In this embodiment, cooling oil is used as the insulating cooling medium for the stator assembly 100. During motor operation, the cooling medium flowing within the second conductors 12, particularly within the linear sections of the second conductors 12, can directly remove heat from the winding conductors at locations with the greatest power loss, namely, at the slots 21b. This effectively achieves cooling at locations with high heat dissipation requirements, thereby meeting current requirements for providing electric drive power to pure electric vehicles or hybrid electric vehicles. In this case, not only is the less efficient cooling water jacket no longer required, but all conductors do not need to be configured as relatively expensive hollow conductors. This ensures cooling efficiency while reducing the overall cost of the stator assembly 100.

[0036] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the claims of the present invention. In the description of the present invention, it should be noted that the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0037] Reference Signs List

[0038] 100 stator assembly

[0039] 10 windings

[0040] 11 First Conductor

[0041] 12 Second conductor

[0042] Channel 121

[0043] 13 Insulation paper

[0044] 20 iron core

[0045] 21 slots

[0046] 21a trough bottom

[0047] 21b notch

Claims

1. A stator assembly (100) for an electric motor, the stator assembly (100) include: The stator core (20) is cylindrical in shape and has a plurality of grooves (21) on its radial inner surface; A winding (10) comprising a first conductor (11) and a second conductor (12), wherein the first conductor (11) and the second conductor (12) are arranged at least partially in at least two layers in the slot portion (21), The first conductor (11) is configured as a solid conductor, and the second conductor (12) is internally configured with a channel (121) penetrating along an extension direction of the second conductor (12). The first conductor (11) is arranged at the bottom of the groove portion (21), and the second conductor (12) is arranged at the groove opening (21b) of the groove portion (21).

2. The stator assembly according to claim 1, in, The first conductor (11) and the second conductor (12) are at least partially arranged in four, six or eight layers within the slot portion (21).

3. The stator assembly according to claim 2, in, The two-layer conductor arranged at the slot opening (21b) of the slot portion (21) is the second conductor (12).

4. The stator assembly according to claim 1, in, The first conductor (11) and the second conductor (12) are made of copper or copper alloy material.

5. The stator assembly according to claim 1, in, The first conductor (11) and the second conductor (12) are U-shaped as a whole.

6. The stator assembly according to claim 1, in, The first conductor (11) and the second conductor (12) are generally straight-line shaped.

7. The stator assembly according to claim 1, in, The first conductor (11) and the second conductor (12) are configured as round wires.

8. The stator assembly according to claim 1, in, The first conductor (11) and the second conductor (12) are configured as flat wires.

9. The stator assembly according to claim 1, in, The channel (121) of the second conductor (12) has a circular or quadrilateral cross section.

10. An electric machine comprising a stator assembly (100) according to any one of claims 1 to 9.

Images