Rotor of axial flux motor, manufacturing method, axial flux motor, and vehicle

Abstract

The invention relates to a rotor of an axial flux motor, a manufacturing method, the axial flux motor and a vehicle. The rotor of the axial magnetic flux motor comprises a rotor disc; and a hollow rotor shaft, the rotor shaft is embedded in the center of the rotor disc so as to be integrated with the rotor disc, the main body of the rotor shaft protrudes in the axial direction relative to one surface of the rotor disc, and a plurality of cooling oil channels are formed in the main body of the rotor shaft. Each of the cooling oil passages penetrates from a radially inner surface to a radially outer surface of the rotor shaft until leading to the rotor disc, and the cooling oil passages extend obliquely so as to have a predetermined inclination angle with respect to the radial direction. According to the axial magnetic flux motor, the heat dissipation of the axial magnetic flux motor can be realized at low cost and high efficiency by utilizing a relatively simple structure and process, and the power density and the torque density of the axial magnetic flux motor are improved while the function and the strength of the axial magnetic flux motor are ensured.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a rotor of an axial flux motor, a manufacturing method, an axial flux motor and a vehicle, and belongs to the technical field of electric machines and vehicles. BACKGROUND

[0002] Axial flux motor (AFM) is concerned in the field of new energy vehicles, industrial servo systems, aerospace and other fields due to its high power density, low torque ripple and compact structure. In the axial flux motor, the stator and the rotor are arranged in parallel along the axial direction, the magnetic flux path is short and there is no tooth and slot structure of the traditional radial motor, thereby significantly reducing mechanical loss and improving efficiency. However, for the axial flux motor, its axial structure characteristics result in that its heat dissipation efficiency is much lower than that of the radial motor, which becomes a problem restricting the performance improvement and reliability.

[0003] In the axial flux motor, the structure of the stator and the rotor stacked along the axial direction makes it difficult for the heat generated by the winding and the permanent magnet to be discharged through the conventional radial heat dissipation channel, and the heat is accumulated in the motor, especially in the stator yoke and the winding end region, resulting in that the local temperature rise exceeds the Curie temperature of the permanent magnet or the tolerance limit of the insulating material. In the prior art, although the improvement scheme of increasing the axial heat dissipation fins or using complex liquid cooling pipelines can partially alleviate the temperature rise problem, the additional structural weight and complexity conflict with the lightweight advantage of the axial flux motor, and a higher cost is required. SUMMARY

[0004] In order to solve the heat dissipation problem in the axial flux motor, the present disclosure provides an axial flux motor which can realize heat dissipation for the axial flux motor at low cost and high efficiency by using a relatively simple structure and process, while ensuring the function and strength of the axial flux motor, and improving the power density and torque density of the axial flux motor.

[0005] Specifically, the first aspect of the present disclosure provides a rotor of an axial flux motor, comprising:

[0006] a rotor disc; and

[0007] a hollow rotor shaft embedded in the center of the rotor disc so as to be integrated with the rotor disc, and the main body of the rotor shaft protrudes axially relative to one surface of the rotor disc,

[0008] the main body of the rotor shaft is formed with a plurality of cooling oil channels, each of the cooling oil channels penetrates from the radial inner surface of the main body of the rotor shaft to the radial outer surface, and reaches the rotor disc, and

[0009] wherein the cooling oil channels extend obliquely so as to have a predetermined oblique angle relative to the radial direction.

[0010] In the rotor of the axial flux motor with the above structure, first, the rotor shaft and the rotor disc can be made into separate parts, and then combined into one by subsequent fitting process. Therefore, the rotor shaft and the rotor disc can be made of different materials to meet their respective needs; the rotor disc can independently complete the processes of fixing the magnetic steel, grooving, etc., and the rotor shaft can also independently complete the forming process of the cooling oil channel, avoiding the processing interference when the rotor shaft and the rotor disc are directly integrated into one product; and when maintenance is needed, only the rotor shaft or the rotor disc can be replaced, reducing the maintenance cost. In addition, the rotor shaft and the rotor disc can be integrated into one by injection molding to make the rotor shaft fit into the rotor disc.

[0011] Secondly, in the rotor of the axial flux motor with the above structure, since the cooling oil channel leading to the rotor disc is provided on the rotor shaft, a cooling passage is formed through the rotor core area. When the motor rotates at high speed, the centrifugal force throws the cooling oil outwards from the center of the rotor shaft, forms a flowing oil film through the cooling oil channel and leads to the surface of the rotor disc, realizes self-circulating cooling driven by centrifugal force, and can achieve heat dissipation with simple structure and low cost. Moreover, since the cooling oil channel is inclinedly arranged, the cooling passage has components in the axial and radial directions, and the cooling oil can also flow in the axial direction, converting the centrifugal force into an axial thrust force, improving the energy utilization rate and enhancing the cooling effect; when the rotor rotates at high speed, the inclination angle can match the direction of the centrifugal movement of the cooling oil, reduce the flow resistance, improve the flow rate of the cooling oil, and avoid the stagnation of the cooling oil; the inclined arrangement also makes the channel length relatively longer, which helps to increase the contact area between the rotor shaft and the cooling oil, so that the cooling oil can take away more heat from the rotor shaft, strengthen the heat exchange efficiency, and further reduce the temperature of the rotor disc.

[0012] Accordingly, according to the rotor of the axial flux motor with the above structure, through efficient cooling, the motor can continuously operate at a higher current density, thereby directly improving the output power and torque. The rotor shaft integrated with the cooling channel reduces the non-functional space occupation, reduces the overall volume of the motor, and improves the power density and torque density. Due to the effective control of temperature rise, the demagnetization of the permanent magnet or the aging of the insulation material can be avoided, so that the motor can fully utilize the performance limits of the magnetic material and the winding.

[0013] Preferably, in the rotor of the first aspect, the rotor comprises: a rotor disc body; a plurality of magnetic steels arranged on the rotor disc body; and a resin covering part covering the rotor disc body and being integrated with the rotor disc body, the plurality of magnetic steels being clamped and fixed between the rotor disc body and the resin covering part.

[0014] According to the rotor of the axial flux motor with the above structure, the resin covering part can directly wrap the magnetic steel and solidify in the injection molding process, and the rotor disc body, magnetic steel fixing and resin covering part forming are completed at one time, thereby reducing the process complexity and simplifying the manufacturing process. In addition, since part of the rotor disc adopts the resin covering part, the iron loss and weight can be reduced, the power density and torque density of the motor are improved, and the rotor weight, cost and reliability can be reduced and enhanced. Moreover, the resin covering part can also fill the gap between the rotor disc and the rotor shaft in the injection molding process, so as to form the rotor disc and the rotor shaft into one body, and the process flow is further simplified.

[0015] Preferably, in the rotor of the first aspect, a plurality of grooves are formed on the resin covering part of the rotor disc, each of the grooves extends from a radially inner end to a radially outer end of the rotor disc, and each of the cooling oil channels communicates with a corresponding one of the grooves. The resin covering part has an inner surface facing the rotor disc body and an outer surface opposite to the inner surface, the grooves are recessed on the outer surface of the resin covering part at positions between adjacent magnetic steels, or / and the grooves are recessed on the inner surface of the resin covering part at positions between adjacent magnetic steels.

[0016] According to the rotor of the axial flux motor with the above structure, by arranging the grooves communicating with the cooling oil channels between the magnetic steels on the rotor disc, the cooling oil can directly flow around the magnetic steels, quickly take away the heat, accurately cool the magnetic steels, effectively avoid the performance degradation of the magnetic steels due to overheating, and ensure the stable operation and output power of the motor. The grooves extend from the radially inner end to the outer end, fully utilize the centrifugal force generated during the rotation of the motor, and the cooling oil flows from the inner end to the outer end under the action of the centrifugal force, forming a smooth heat dissipation path, so that the heat can be quickly dissipated from the inside of the motor, and each of the cooling oil channels communicates with a corresponding one of the grooves, ensuring that the cooling oil can be evenly distributed to each magnetic steel area, and improving the overall heat dissipation efficiency.

[0017] In addition, in the rotor of the axial flux motor with the above structure, since the grooves are formed in the resin covering part, compared with the traditional process of separately performing magnetic steel press fitting, resin injection molding and groove machining, the present disclosure only needs a simple one-step molding process to simultaneously complete the magnetic steel fixing, resin covering part and groove forming in a single injection molding process, thereby greatly simplifying the manufacturing process and shortening the production cycle; the grooves are integrally formed in the resin covering part for the cooling oil to flow, without the need for additional complex cooling devices or structures, thereby reducing the use of materials and the assembly workload, and reducing the manufacturing cost of the motor; and since the grooves are directly formed during injection molding, the size deviation and surface burr problems caused by traditional machining (such as milling and polishing) can also be avoided.

[0018] Preferably, in the rotor of the first aspect, each of the grooves extends along a radial straight line of the rotor disc, and the grooves have a uniform depth along the radial direction.

[0019] According to the rotor of the axial flux motor with the above structure, through the radial straight line extending grooves, the cooling oil flow guiding efficiency is ensured without the need for special-shaped design of the magnetic steel, and the standardization of the magnetic steel, the cooling efficiency and the low cost of manufacturing are taken into account. The grooves extend along a radial straight line, and after the cooling oil flows from the cooling oil channel of the rotor shaft, it spreads uniformly to the edge of the rotor disc along the grooves, the flow distribution is more uniform, the flow is more smooth, and the heat exchange efficiency is improved.

[0020] Preferably, in the rotor of the first aspect, each of the grooves extends along a radial straight line of the rotor disc, and the grooves have a uniform depth along the radial direction.

[0021] According to the rotor of the axial flux motor with the above structure, in addition to the technical effects of the radial straight line extending grooves mentioned earlier, by making the grooves have varying depths along the radial direction, i.e. adjusting the depth according to the heat generation characteristics of the magnetic steel, the cooling efficiency is further improved.

[0022] Preferably, in the rotor of the first aspect, the main body of the rotor shaft is in the shape of a truncated cone, so that the outer circumferential surface of the main body of the rotor shaft gradually tapers away from the rotor disc.

[0023] According to the rotor of the axial flux motor with the above structure, compared with the traditional simple cylindrical rotor shaft, the main body of the rotor shaft in the shape of a truncated cone helps the air to flow more smoothly over the surface of the rotor shaft, reduces wind resistance, reduces air noise, reduces energy loss due to wind resistance, and improves the efficiency of the motor. In addition, due to the truncated cone shape of the main body of the rotor shaft, the distribution of centrifugal force on the shaft is more uniform, as the outer diameter of the shaft gradually decreases, the stress changes caused by centrifugal force at different positions on the shaft are relatively gentle, avoiding the problem of local stress concentration, and improving the fatigue life of the rotor shaft. In addition, due to the truncated cone shape of the main body of the rotor shaft, the flow of cooling oil in the channel is more smooth. As the outer diameter of the shaft gradually decreases, the cooling oil can flow more quickly from the inner surface of the shaft to the radial outer surface under the action of centrifugal force, enhancing the cooling effect. The truncated cone shape also helps to save materials, thereby reducing material costs and reducing weight. In addition, due to the adoption of the truncated cone shape, the connecting structure such as the bolt through hole can be processed at the radially outer end with a relatively small axial thickness, so that the axial length of the connecting structure is relatively short, reducing the processing difficulty of the connecting structure. Accordingly, only a relatively short bolt or other cooperating connecting structure is needed to realize the connection and fixation with other rotor discs, reducing the assembly difficulty, and the short bolt can also improve the fatigue resistance, light weight and reliability.

[0024] Preferably, in the rotor of the first aspect, the main body of the rotor shaft is further provided with a plurality of bolt through holes for bolts to pass through, each of the bolt through holes penetrates the main body of the rotor shaft in an axial direction at a position not interfering with the cooling oil channel.

[0025] According to the rotor of the axial flux motor with the above structure, by providing the bolt through holes, a plurality of rotor discs can be conveniently connected as needed, for example, for an R-S-R structure, two rotors can be connected into one by only inserting bolts through the bolt through holes of the two rotor discs and fastening. Compared with the traditional integral casting or welding of two rotor discs with a mandrel, keyway connection and the like, the connection operation is simpler and the precision and reliability are better.

[0026] Preferably, in the rotor of the first aspect, the cooling oil channel comprises a main channel and a branch channel, a branch side inlet of the branch channel located on the inner side in the radial direction is arranged axially separately from a main inlet of the main channel located on the inner side in the radial direction, and the branch channel merges into the main channel as it progresses toward the outer side in the radial direction.

[0027] According to the rotor of the axial flux motor with the above structure, since the branch channel is provided in addition to the main channel, the volume of the cooling oil channel can be increased, and the cooling effect is further enhanced. In addition, the branch channel can also be a backup channel, when the main channel is blocked or flows poorly due to some reason, the cooling oil can flow through the branch channel, and vice versa.

[0028] Preferably, in the rotor of the first aspect, the main inlet of the main channel and / or the branch side inlet of the branch channel is in the shape of a bell mouth.

[0029] According to the rotor of the axial flux motor with the above structure, since the main inlet of the main channel and / or the branch side inlet of the branch channel is in the shape of a bell mouth, i.e. in the shape of an expanding mouth, the cooling oil can be better introduced into the cooling oil channel, and the bell mouth shape is also beneficial to reducing the pressure loss at the inlet and reducing the flow resistance, thereby further improving the heat dissipation effect.

[0030] The second aspect of the present disclosure provides a manufacturing method of the rotor of the axial flux motor of the first aspect, comprising: preparing a rotor disc body of a rotor disc; integrally molding a resin covering part on the rotor disc body by injection molding in a state where the magnetic steel is positioned on the rotor disc body, and clamping and fixing a plurality of the magnetic steel between the rotor disc body and the resin covering part; wherein a plurality of grooves are integrally molded on the resin covering part during the injection molding, the grooves are recessed on the resin covering part between adjacent magnetic steels.

[0031] According to the manufacturing method of the second aspect, the positioning of the magnetic steel, the forming of the covering part and the groove processing are combined into one process through an injection molding process, so that the fixing of the magnetic steel, the forming of the resin covering part and the formation of the groove are completed simultaneously in a single injection molding process, which greatly simplifies the manufacturing process and shortens the production cycle, improves the reliability of the magnetic steel fixing and the structural strength, and effectively meets the heat dissipation requirements. The groove is integrally formed in the resin covering part to flow the cooling oil, without the need for additional complex cooling devices or structures, reducing the use of materials and the assembly workload, and reducing the manufacturing cost of the motor. Moreover, since the groove is directly formed during injection molding, the size deviation and surface burr problems caused by traditional machining (such as milling and polishing) can be avoided. That is, according to the manufacturing method, through injection integrated forming, the fixing of the magnetic steel, the forming of the covering part and the heat dissipation structure are synergistically optimized, which is beneficial to efficient production, high reliability, lightweight and excellent heat dissipation performance.

[0032] The third aspect of the present disclosure provides an axial flux motor having the rotor of the first aspect. The fourth aspect of the present disclosure provides a vehicle having the axial flux motor of the third aspect.

[0033] According to the axial flux motor and the vehicle having the above structure, since the rotor of the first aspect is adopted, the technical effects of the first aspect can also be achieved.

[0034] Hereinafter, embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings, so as to facilitate easier understanding of the technical solutions of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0035] The accompanying drawings are used to better understand the present disclosure, and do not constitute an improper limitation on the present disclosure. Among them:

[0036] Figure 1 A schematic side view of an axial flux motor according to an embodiment of the present disclosure is shown;

[0037] Figure 2 A schematic perspective view of a rotor disc of an axial flux motor according to an embodiment of the present disclosure is shown;

[0038] Figure 3 A schematic plan view of a rotor disc of an axial flux motor according to an embodiment of the present disclosure is shown;

[0039] Figure 4 A schematic side view of a rotor disc of an axial flux motor according to an embodiment of the present disclosure is shown;

[0040] Figure 5 A schematic A-A sectional view of the rotor disc of Figure 3 is shown.

[0041] LIST OF REFERENCE NUMBERS

[0042] 10 axial flux electric machine

[0043] 11 first rotor

[0044] 12 stator

[0045] 13 second rotor

[0046] 14 rotation shaft

[0047] 100 rotor

[0048] 110 rotor disk

[0049] 120 rotor disk body

[0050] 121 overflow hole

[0051] 130 resin covering portion

[0052] 131 recess

[0053] 132 overflow portion

[0054] 140 rotor shaft

[0055] 140A main body

[0056] 140B fitting portion

[0057] 141 cooling oil passage

[0058] 142 inlet

[0059] 143 outlet

[0060] 144 screw through hole

[0061] 145 outer peripheral surface

[0062] α inclination angle DETAILED DESCRIPTION

[0063] Hereinafter, the technical solution of the present application will be explained more clearly by describing a specific embodiment of the present application with reference to the accompanying drawings.

[0064] It should be noted that the drawings of the present application are merely schematic diagrams simply showing parts related to the solution of the present application and do not show some unnecessary parts that can exist, and therefore the drawings should not be understood as limiting the present application, which can be different from the actual structure in use. In addition, it should also be understood that the terms "upper", "lower", "left", "right", "front", "back", etc. indicating the position or location that can appear in the following description are for the purpose of convenient explanation, but are not limiting. Also, for the sake of clarity and brevity, the description in the following description omits the description of the well-known functions and structures.

[0065] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form a new technical solution. Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0066] Figure 1 FIG. 1 shows a schematic side view of an axial flux motor 10 according to an embodiment of the present invention. Figure 1 As shown, the axial flux motor 10 exemplarily adopts an RSR structure, i.e., a configuration of dual rotors and a single stator, and specifically includes a first rotor 11, a second rotor 13, a stator 12 located between the first rotor 11 and the second rotor 13, and a rotating shaft 14 connecting the first rotor 11 and the second rotor 13. It is worth noting that Figure 1 This is merely a schematic diagram, intended solely to illustrate the reference configuration of an exemplary embodiment of an axial flux motor, and is not intended to limit the shapes of the rotor, stator, or shaft. In this embodiment, the first rotor 11 and the second rotor 13 may have the same structure. Therefore, the first rotor 11 will be used as an example of the rotor 100 of the axial flux motor.

[0067] In addition, it should be understood that Figure 1 The RSR structure is merely an example. Axial flux motors may also employ other structures, such as an SRS structure (i.e., a dual-stator and single-rotor configuration); an RS structure (i.e., a single-rotor and single-stator configuration); and multi-laminate structures such as RSRS and RSRSR. Axial flux motors of various configurations may be employed as long as they include the rotor 100 described in the embodiment.

[0068] <First embodiment>

[0069] Below, we will refer to Figures 2-5 The rotor 100 of the axial flux motor according to the first embodiment of the present disclosure will be described. Hereinafter, the radial direction refers to the diameter direction of the rotor disk, and the axial direction refers to the axis direction of the rotor shaft, which is also a direction perpendicular to the radial direction.

[0070] like Figures 2-5 As shown, in this embodiment, the rotor 100 includes: a rotor disk 110; and a hollow rotor shaft 140, which is embedded in the center of the rotor disk 110 and thus becomes one with the rotor disk 110. The rotor shaft 140 may include a main body 140A and an embedding portion 140B. The main body 140A of the rotor shaft 140 protrudes from the front side of the rotor disk 110 (the surface on the side where the magnetic steel is provided), and the embedding portion 140B of the rotor shaft 140 may also slightly protrude from the back side of the rotor disk 110.Figure 3 As shown, the outer diameter D1 of the rotor disc 110 can be, for example, 360 mm, and the inner diameter D2 of the rotor shaft 140 can be, for example, 54 mm; as shown, Figure 4 As shown, the total thickness t1 of the rotor 100 at the portion of the rotor shaft 140, that is, the thickness t1 of the rotor shaft 140, is, for example, 35.2 mm, the thickness t2 between the front face of the rotor disc 110 and the end face of the fitting portion 140B of the rotor shaft 140 is, for example, 9.2 mm, and the thickness t3 between the back face of the rotor disc 110 and the end face of the fitting portion 140B of the rotor shaft 140, that is, the thickness t3 by which the fitting portion 140B of the rotor shaft 140 protrudes from the back face of the rotor disc 110, is, for example, 2.7 mm.

[0071] The main body 140A of the rotor shaft 140 is formed with a plurality of cooling oil passages 141, each of which extends from the radially inner surface to the radially outer surface of the rotor shaft 140 until reaching the rotor disc 110. In the present embodiment, the number of the cooling oil passages 141 is 6 as shown, but this number is merely exemplary and is not limiting, and a suitable number can be selected according to actual conditions.

[0072] The main body of the rotor shaft 140 is configured in a frustum shape as shown, that is, the outer peripheral surface 145 of the rotor shaft 140 gradually tapers away from the rotor disc 110. Compared with a conventional cylindrical rotor shaft, the frustum-shaped main body of the rotor shaft 140 helps the air to flow more smoothly over the surface of the rotor shaft 140, reduces wind resistance, reduces air noise, reduces energy loss due to wind resistance, and improves the efficiency of the motor. In addition, due to the frustum shape of the main body of the rotor shaft 140, the distribution of centrifugal force on the shaft is more uniform, and as the outer diameter of the shaft gradually decreases, the stress change caused by the centrifugal force at different positions of the shaft is relatively gentle, avoiding the problem of local stress concentration, and improving the fatigue life of the rotor shaft 140. In addition, due to the frustum shape of the main body of the rotor shaft, the flow of cooling oil in the cooling oil passages 141 is more smooth. As the outer diameter of the shaft gradually decreases, the cooling oil can flow more quickly from the inner surface to the radially outer surface of the shaft under the action of centrifugal force, enhancing the cooling effect. The frustum shape also helps to save materials, thereby reducing material costs and reducing weight. In addition, due to the adoption of the frustum shape, the connecting structure such as the bolt through hole 144 (to be described later) can be machined at the radially outer end with a relatively small axial thickness, so that the axial length of the connecting structure is relatively short, reducing the machining difficulty of the connecting structure, and accordingly, only a relatively short bolt or the like is needed to cooperate with the connecting structure to achieve the connection and fixation with other rotor discs, reducing the assembly difficulty, and the short bolt can also improve the fatigue resistance, light weight and reliability.

[0073] In the present embodiment, the rotor 100 integrally has the rotor disk 110 and the rotor shaft 140 which are fitted together. Therefore, the rotor shaft 140 and the rotor disk 110 can be manufactured as separate parts, and are combined into one by a subsequent fitting process, so that the rotor shaft 140 and the rotor disk 110 can be made of different materials to meet their respective requirements; the rotor disk 110 can independently complete the processes of fixing the magnet steel, slotting, etc., and the rotor shaft 140 can independently complete the process of forming the cooling oil passage, avoiding the processing interference when the rotor shaft and the rotor disk are directly integrated into one product, and when there is a maintenance requirement, only the rotor shaft 140 or the rotor disk 110 can be replaced, reducing the maintenance cost. In addition, the rotor shaft and the rotor disk can be integrated by injection molding to make the rotor shaft 140 fit into the rotor disk 110 to become one. The specific way of fitting the rotor shaft into the rotor disk to become one is not limited here.

[0074] In the rotor 100 of the present embodiment, as shown in Figure 5 , the cooling oil passage 141 extends obliquely in the rotor shaft 140 to have a predetermined oblique angle a with respect to the radial direction. In the present embodiment, the oblique angle a of the cooling oil passage 141 is set to 10°, for example, but this is not limiting, and the angle can be adjusted between 10 to 40° (including 40°). The cooling oil passage 141 has an inlet 142 on the inner side in the radial direction and an outlet 143 on the outer side in the radial direction. The hole diameter h1 of the cooling oil passage 141 is 3 mm, for example, as shown in Figure 5 . The distance h3 between the center of the inlet 142 of the cooling oil passage 141 and the end surface of the fitting portion 140B of the rotor shaft 140 is 15 mm, for example.

[0075] The cooling oil channel 141 leading to the rotor disc 110 is arranged on the rotor shaft 140, forming a cooling passage through the rotor core area. When the motor rotates at high speed, the centrifugal force will throw the cooling oil outwards from the center of the rotor shaft 140, forming a flowing oil film through the cooling oil channel and leading to the surface of the rotor disc 110, realizing self-circulation cooling driven by centrifugal force, which can achieve heat dissipation with simple structure and low cost. Moreover, since the cooling oil channel 141 is arranged obliquely, the cooling passage has components in both the axial and radial directions, which can guide the cooling oil to flow in the axial direction as well, converting the centrifugal force into axial thrust, improving energy utilization and enhancing cooling effect; when the rotor 100 rotates at high speed, the inclination α can match the direction of the centrifugal motion of the cooling oil, reducing flow resistance, improving the flow rate of the cooling oil, and avoiding the stagnation of the cooling oil; the oblique arrangement also makes the channel length relatively longer, which helps to increase the contact area between the rotor shaft and the cooling oil, so that the cooling oil can take away more heat from the rotor shaft, strengthening the heat exchange efficiency and further reducing the temperature of the rotor disc. The rotor with oblique cooling oil channel 141 in the embodiment allows the motor to operate continuously at a higher current density through efficient cooling, thereby directly improving the output power and torque. The integrated cooling channel of the rotor shaft reduces the occupation of non-functional space, making the overall volume of the motor smaller and improving the power density and torque density. Due to effective control of temperature rise, the demagnetization of permanent magnets or the aging of insulation materials can be avoided, so that the motor can fully utilize the performance limits of magnetic materials and windings.

[0076] For the rotor disc 110 of the rotor 100, it can include: a rotor disc body 120; a plurality of magnetic steels (not shown) arranged on the rotor disc body 120; and a resin covering part 130 covering the rotor disc body 120 and integrated with the rotor disc body 120, the plurality of magnetic steels being clamped and fixed between the rotor disc body 120 and the resin covering part 130. The magnetic steels can adopt standard magnetic steels, which are uniformly arranged on the surface of the rotor disc body 120 in the circumferential direction. In the present embodiment, the magnetic steels are not visible because they are covered by the resin covering part, so they are not shown in the figure. It can be understood from Figure 2 and Figure 3 that the 12 magnetic steels are uniformly arranged at positions between adjacent grooves 131 (to be described later). The number of magnetic steels is only an example and is not limiting, and can be selected as needed.

[0077] The resin covering 130 may be formed by curing a highly fluid and high-strength resin material. It is integrally formed on the rotor disk body 120 through injection molding, filling the gaps between the magnetic steels and securely bonded to the rotor disk body 120. By providing overflow holes 121 on the rotor disk body 120, excess resin material during injection molding can be accommodated in and discharged through overflow holes 121. Furthermore, the bond between the overflow holes 121 and the overflow portion 132 formed by the resin material in the overflow holes 121 also acts as an anchor, further strengthening the bond between the resin covering 130 and the rotor disk body 120.

[0078] Since the rotor disk 110 is divided into a rotor disk body 120 and a resin covering 130, the resin covering 130 can directly wrap the magnetic steel and solidify during the injection molding process, completing the rotor disk body 120, the magnetic steel fixation and the resin covering 130 molding at one time, reducing the process complexity and simplifying the manufacturing process. In addition, since a portion of the rotor disk 110 adopts the resin covering 130, it can reduce iron loss and weight, improve the power density and torque density of the motor, and also help to reduce the weight of the rotor, reduce costs and enhance reliability. Moreover, the resin covering 130 can also fill the gap between the rotor disk 110 and the rotor shaft 140 during the injection molding process, thereby molding the rotor disk 110 and the rotor shaft 140 into one piece, taking into account the process of integrating the rotor shaft embedded in the rotor disk, and the process flow can be further simplified.

[0079] On the resin covering portion 130 of the rotor disk 110, as shown Figures 2-5 As shown, a plurality of grooves 131 are formed. In this embodiment, based on the number of magnetic steels being 12, the number of grooves 131 is correspondingly set to 12, that is, one groove 131 is set between each adjacent magnetic steel. The grooves 131 extend from the radial inner end to the radial outer end of the rotor disk 110, and each cooling oil channel 141 is connected to a corresponding groove 131. More specifically, the outlet 143 of the cooling oil channel 141 is connected to the groove 131. In this embodiment, although not every groove 131 is connected to a corresponding cooling oil channel 141, due to the frustum-shaped arrangement of the rotor shaft, as shown in FIG. Figure 2 and Figure 4 As shown, the upper end surface of the outlet 143 of the cooling oil channel 141 of the rotor shaft 140 can be higher than the surface of the rotor disk. In other words, the depth of the outlet 143 is greater than the depth of the groove 131. Therefore, when the cooling oil is thrown out from the outlet 143, not all of it may flow into a connected groove 131. Part of the cooling oil may also flow to the surface of the rotor disk and then enter other grooves 131, further improving the cooling effect.

[0080] By setting the grooves 131 on the rotor disc 110 between the magnetic steel, and part of the grooves 131 are communicated with the cooling oil channel 141, the cooling oil can directly flow around the magnetic steel, quickly take away the heat, accurately cool the magnetic steel, effectively avoid the performance decline of the magnetic steel due to overheating, and protect the stable operation and output power of the motor. The grooves 131 extend from the radial inner end to the outer end, fully utilize the centrifugal force generated when the motor rotates, and the cooling oil flows from the inner end to the outer end under the action of the centrifugal force, forming a smooth heat dissipation path, so that the heat can be quickly dissipated from the inside of the motor, ensuring that the cooling oil can be evenly distributed to each magnetic steel area, and improving the overall heat dissipation efficiency.

[0081] The resin covering part 130 has an inner surface facing the rotor disc body 120 and an outer surface opposite to the inner surface. As shown in the figure, in the present embodiment, each groove 131 is recessed on the outer surface of the resin covering part 130 at the position between adjacent magnetic steels. Since the grooves 131 are formed in the resin covering part 130, compared with the traditional process of separating magnetic steel pressing, resin injection, and cooling channel processing, the present disclosure only needs a simple one-step molding process to complete the molding of the magnetic steel fixing, the resin covering part 130 and the grooves 131 at the same time in a single injection process, greatly simplifying the manufacturing process and shortening the production cycle; the grooves 131 are integrally formed in the resin covering part for cooling oil to flow, without the need for additional complex cooling devices or structures, reducing the use of materials and the workload of assembly, and reducing the manufacturing cost of the motor; moreover, since the grooves 131 are directly formed during injection molding, the size deviation and surface burr problems caused by traditional machining (such as milling and polishing) can also be avoided.

[0082] As shown in Figure 2 and Figure 3 , each groove 131 extends linearly along the radial direction of the rotor disc, and the grooves 131 have a uniform depth h2 along the radial direction. In the present embodiment, the depth h2 of the grooves 131 is, for example, 1mm, and this depth h2 is only an example and is not limiting. By extending the grooves 131 linearly along the radial direction, the cooling oil guiding efficiency is ensured, and the magnetic steel does not need to be designed in a special shape, which takes into account the standardization of the magnetic steel, the high efficiency of cooling, and the low cost of manufacturing. The grooves 131 extend linearly along the radial direction, and after the cooling oil flows into the grooves 131 from the cooling oil channel of the rotor shaft 140, it spreads uniformly to the edge of the rotor disc 110, the flow distribution is more uniform, the flow is smoother, and the heat exchange efficiency is improved.

[0083] In order to realize the connection between the rotors in the case of multiple rotors, in the present embodiment, the rotor shaft 140 of the rotor 100 is also provided with a plurality of bolt through holes 144 for the bolts to pass through, and each bolt through hole 144 penetrates the rotor shaft 140 along the axial direction without interfering with the cooling oil channel 141. Figure 2 andFigure 3 As shown, in the present embodiment, the bolt through holes are uniformly arranged in the axial direction with 6 in number, which is merely an example and is not restrictive, the number of bolt through holes can be more than 6 or less than 6.

[0084] By arranging the bolt through holes 144, a plurality of rotor disks can be conveniently connected as needed, for example, for an R-S-R structure, two rotors can be connected into one body by simply inserting the bolt through the bolt through holes of the two rotor disks and fastening, thus forming the core part of the axial flux motor. Compared with the traditional integral casting or welding of the two rotor disks with the mandrel, keyway connection, etc., the connection operation is simpler and the precision and reliability are better.

[0085] <Second Embodiment>

[0086] Next, the second embodiment of the rotor of the axial flux motor of the present disclosure is described. The second embodiment is basically the same as the first embodiment, and the difference is only in the cooling oil passage formed in the rotor shaft 140. The cooling oil passage of the second embodiment is configured to include a branch passage in addition to the cooling oil passage 141 of the first embodiment as the main passage. The branch side inlet of the branch passage on the radially inner side is arranged separately from the main inlet of the main passage on the radially inner side in the axial direction, and the branch passage merges into the main passage as it progresses toward the radially outer side.

[0087] For example, the branch side inlet of the branch passage can be arranged closer to the rotor disk than the main inlet of the main passage.

[0088] Since the branch passage is arranged in addition to the main passage, the volume of the cooling oil passage can be increased, and the cooling effect can be further enhanced. In addition, the branch passage can also serve as a backup passage, when the main passage is blocked or flows poorly due to some reason, the cooling oil can flow through the branch passage, and vice versa.

[0089] <Third Embodiment>

[0090] Next, the third embodiment of the rotor of the axial flux motor of the present disclosure is described. The third embodiment is basically the same as the first embodiment, and the difference is only in the shape of the inlet 142 of the cooling oil passage 141 formed in the rotor shaft 140. In the present embodiment, the shape of the inlet of the cooling oil passage can be configured to be in the shape of a bell mouth, i.e., an expanded port shape.

[0091] Since the inlet of the cooling oil passage is in the shape of a bell mouth, i.e., an expanded port shape, the cooling oil can be better introduced into the cooling oil passage, and the bell mouth shape is also beneficial to reduce the pressure loss at the inlet and reduce the flow resistance, thus further improving the heat dissipation effect.

[0092] <Fourth Embodiment>

[0093] Next, a fourth embodiment of the rotor of the axial flux motor of the present disclosure will be described. The fourth embodiment is basically the same as the first embodiment, and the difference is only that the grooves 131 are recessed on the inner surface of the resin covering portion 130. In the first embodiment, considering that the grooves 131 are formed on the outer surface of the resin covering portion 130, the bonding area between the resin covering portion 130 and the rotor disc body 120 is larger, and the bonding strength is higher, so the grooves 131 are formed on the outer surface.

[0094] In the fourth embodiment, considering that the grooves 131 are formed on the inner surface of the resin covering portion 130, the grooves 131 are closer to the rotor disc body 120 and the magnetic steel on the rotor disc body 120, and the cooling oil flowing in the grooves 131 is also correspondingly closer to the rotor disc body 120 and the magnetic steel on the rotor disc body 120, so the cooling effect is relatively better, and therefore each groove 131 is configured to be recessed on the inner surface of the resin covering portion and formed at a position between adjacent magnetic steels.

[0095] In addition, considering the balance between bonding strength and cooling effect, it can also be that part of the grooves 131 are formed on the inner surface of the resin covering portion, and part of the grooves 131 are formed on the outer surface.

[0096] <5th Embodiment>

[0097] Next, a fifth embodiment of the rotor of the axial flux motor of the present disclosure will be described. The fifth embodiment is basically the same as the first embodiment, and the difference is only that the grooves extending linearly along the radial direction of the rotor disc are configured to have varying depths in the radial direction.

[0098] By making the grooves have varying depths in the radial direction, that is, adjusting the depths in sections according to the heat generation characteristics of the magnetic steels, the cooling efficiency is further improved.

[0099] <6th Embodiment>

[0100] The foregoing first to fifth embodiments describe the structure of the rotor of the axial flux motor of the present disclosure. In the sixth embodiment, a manufacturing method of the foregoing rotor of the axial flux motor will be described.

[0101] The manufacturing method of the rotor of the axial flux motor of the present embodiment includes: preparing a rotor disc body of a rotor disc; integrally molding a resin covering portion on the rotor disc body by injection molding in a state where magnetic steels are positioned on the rotor disc body, and a plurality of the magnetic steels are clamped and fixed between the rotor disc body and the resin covering portion; wherein a plurality of grooves are integrally molded on the resin covering portion during the injection molding, and the grooves are recessed on the resin covering portion and formed between adjacent magnetic steels.

[0102] According to the manufacturing method of the embodiment, the positioning of the magnetic steel, the forming of the covering part and the groove processing are combined into one process through the injection molding process, so that the fixing of the magnetic steel, the forming of the resin covering part and the formation of the groove are completed simultaneously in a single injection molding process, which greatly simplifies the manufacturing process and shortens the production cycle, improves the reliability of the magnetic steel fixing and the structural strength, and effectively meets the heat dissipation requirements. The groove is integrally formed in the resin covering part to flow the cooling oil, without the need for additional complex cooling devices or structures, reducing the use of materials and the assembly workload, and reducing the manufacturing cost of the motor. Moreover, since the groove is directly formed during injection molding, the size deviation and surface burr problems caused by traditional machining (such as milling and polishing) can be avoided. That is, according to the manufacturing method, through the integrally formed injection molding, the fixing of the magnetic steel, the forming of the covering part and the heat dissipation structure are synergistically optimized, which is beneficial to efficient production, high reliability, lightweight and excellent heat dissipation performance.

[0103] In addition, the above manufacturing method can further include integrally forming the rotor shaft with the rotor disc by injection molding, and directly forming the cooling oil passage during the injection molding process.

[0104] <application example>

[0105] Next, an application example of the axial flux motor according to the present disclosure will be described. The axial flux motor is described by way of example applied to a vehicle.

[0106] During the operation of the axial flux motor, the cooling oil enters from the axial end of the rotor shaft 140 through an external oil pump system (or an oil supply device integrated in the motor), is transported to the inlet 142 of the internal cooling oil passage 141 through the central oil channel of the rotor shaft 140. Through the centrifugal force generated by the high-speed rotation of the rotor shaft 140, the cooling oil is further pushed from the inlet 142 into the cooling oil passage 141 and flows to the radially outer outlet 143. At this time, under the combined action of the centrifugal force and the inclined design of the passage, the cooling oil quickly flows to the surface direction of the rotor disc 110, flows out of the outlet 143 of the cooling oil passage 141, and enters the groove 131 in the rotor disc 110 (part of the cooling oil also flows to the surface of the rotor disc), so that the cooling oil is evenly diffused along the groove 131 from the radially inner end (close to the shaft center) to the radially outer end (edge area) of the rotor disc 110.

[0107] When the cooling oil flows in the groove 131, it covers the surface of the rotor disc 110 and the magnetic steel area, and absorbs the heat generated by the high-speed rotation and electromagnetic loss of the rotor disc. The straight design of the groove 131 in combination with the centrifugal force generated by the rotation of the rotor forms a dynamic turbulent flow of the oil film, further improving the heat dissipation efficiency.

[0108] The cooling oil completing heat dissipation is spun out at the edge of the rotor disc 110 at high speed and enters a preset oil collecting cavity or oil guide groove in the motor housing. The cooling oil in the oil collecting cavity is returned to the oil pump system through an external pipeline, can remove impurities by passing through a filter, and can be cooled by a radiator to realize stable control of the oil temperature. The cooled cooling oil is again delivered to the inlet of the rotor shaft 140 by the oil pump to form a closed loop circulation system to continuously dissipate heat for the motor.

[0109] The axial flux motor of the present disclosure has been described in detail above, which effectively reduces the temperature of the rotor disc and the magnetic steel during high-speed driving of the vehicle. In the rotor integrated molding process, the cooling channel of the rotor disc is directly molded by a mold. While better and faster fixing of the rotor and the special-shaped magnetic steel of the axial flux motor is achieved, the cooling capacity is also optimized.

[0110] By using a high-flow and high-strength resin material, the resin material can fully fill the gap between the magnetic steel and the rotor disc at high temperature during the molding of the rotor, and after cooling, the rotor disc and the magnetic steel are integrated together, which improves the strength of the rotor assembly. At the same time, the groove formed as a cooling channel during the injection molding further cools the rotor and its magnetic steel, i.e., without additional increase in the process difficulty of the rotor molding, the rotor cooling system is increased, so that the rotor can operate at a higher speed compared to other axial flux motors, and can operate at high speed for a longer time, reducing the risk of demagnetization of the magnetic steel, improving the peak torque duration, and further improving the power density and torque density of the axial flux motor.

[0111] By machining a special oil cooling channel in the interior of the rotor shaft, the cooling oil is made to flow to the rotor disc through the cooling oil channel by centrifugal force, which cools the rotor disc and its magnetic steel assembly more fully.

[0112] The above specific embodiments do not constitute a limitation on the scope of protection of the present application. The numerical values in the above examples are only examples and are not limiting. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can occur depending on design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A rotor for an axial flux motor, characterized in that: include: rotor disc; as well as a hollow rotor shaft, the rotor shaft being fitted into the center of the rotor disk to form an integral body with the rotor disk, and the main body of the rotor shaft protruding axially relative to one surface of the rotor disk; The main body of the rotor shaft is formed with a plurality of cooling oil channels, each of which extends from the radial inner surface to the radial outer surface of the main body of the rotor shaft until it leads to the rotor disk, and The cooling oil channel extends obliquely to have a predetermined inclination angle relative to a radial direction.

2. The rotor according to claim 1, characterized in that The rotor disk comprises: rotor disc body; a plurality of magnets disposed on the rotor disk body; and A resin covering portion covers the rotor disk body and is integrated with the rotor disk body, and a plurality of magnetic steels are sandwiched and fixed between the rotor disk body and the resin covering portion.

3. The rotor according to claim 2, characterized in that A plurality of grooves are formed on the resin covering portion of the rotor disk, each of the grooves extending from the radial inner end to the radial outer end of the rotor disk, and each of the cooling oil channels is connected to a corresponding one of the grooves, and The resin covering portion has an inner surface facing the rotor disk body and an outer surface opposite to the inner surface, the groove is concavely formed on the outer surface of the resin covering portion at a position between adjacent magnetic steels, or / and the groove is concavely formed on the inner surface of the resin covering portion at a position between adjacent magnetic steels.

4. The rotor according to claim 3, characterized in that Each of the grooves extends along a radial straight line of the rotor disk, and has a uniform depth along the radial direction.

5. The rotor according to claim 3, characterized in that Each of the grooves extends along a straight radial direction of the rotor disk, and at least a portion of the grooves has a varying depth along the radial direction.

6. The rotor according to any one of claims 1 to 5, characterized in that: The main body of the rotor shaft is in a frustum shape, such that an outer peripheral surface of the main body of the rotor shaft gradually becomes thinner as it moves away from the rotor disk.

7. The rotor according to claim 6, characterized in that The main body of the rotor shaft is further provided with a plurality of bolt through holes for bolts to pass through, and each of the bolt through holes axially penetrates the main body of the rotor shaft at a position that does not interfere with the cooling oil channel.

8. The rotor according to any one of claims 1 to 7, characterized in that: The cooling oil channel includes a main channel and a branch channel. The branch side inlet of the branch channel located on the radial inner side and the main inlet of the main channel located on the radial inner side are arranged axially apart from each other, and the branch channel merges into the main channel as it moves toward the radial outer side.

9. The rotor according to claim 8, characterized in that The main inlet of the main channel and / or the branch side inlet of the branch channel are in a trumpet shape.

10. A method for manufacturing a rotor of an axial flux motor according to any one of claims 1 to 9, characterized in that: include: preparing a rotor disc body of the rotor disc; In a state where the magnetic steel is positioned on the rotor disk body, a resin covering portion is integrally formed on the rotor disk body by injection molding, and a plurality of the magnetic steels are sandwiched and fixed between the rotor disk body and the resin covering portion; During the injection molding, a plurality of grooves are formed on the resin covering portion, and the grooves are formed concavely on the resin covering portion between adjacent magnetic steels.

11. An axial flux motor, characterized in that: The axial flux motor includes the rotor according to any one of claims 1 to 9.

12. A vehicle, characterized in that: The vehicle includes the axial flux motor according to claim 11 .

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