Rotor assembly, electric motor, and new energy vehicle

Abstract

Provided in the present invention are a rotor assembly, an electric motor, and a new energy vehicle. The rotor assembly comprises: a rotor core, a first rotor end plate, a second rotor end plate, and an electric motor rotating shaft, wherein the rotor core is coaxially fixed to the electric motor rotating shaft, and the first rotor end plate and the second rotor end plate are respectively fixed to two ends of the rotor core and are coaxially fixed with the electric motor rotating shaft. The rotor core is provided first ventilation holes distributed in axial symmetry, the first ventilation holes being distributed on a first reference circle with a first diameter, and the first rotor end plate and the second rotor end plate are respectively provided with second ventilation holes and third ventilation holes distributed in axial symmetry, the second ventilation holes being distributed on a second reference circle with a second diameter, and the third ventilation holes being distributed on a third reference circle with a third diameter; stepped ventilation channels distributed in axial symmetry are formed by the first ventilation holes, the second ventilation holes, and the third ventilation holes. In the present invention, the operating temperature of the rotor assembly can be effectively reduced by means of the stepped ventilation channels, and the rotor end plates have a simple structure, enabling the manufacturing cost to be reduced.

Description

Rotor assembly, motor and new energy vehicle Technical Field

[0001] The present invention relates to the field of motor technology, and in particular to a rotor assembly, a motor and a new energy vehicle. Background Art

[0002] The drive motor is a core component of the electric drive assembly for new energy vehicles. It comprises a housing, stator core, rotor core, windings, permanent magnets, a rotating shaft, rotor end plates, and a pressure ring. During motor operation, the stator and rotor cores experience alternating magnetic fields, generating iron losses. The windings generate copper losses when energized. Furthermore, hysteresis and eddy current losses occur in the stator and rotor cores and permanent magnets. These losses can cause excessive motor temperature rise during operation, accelerating motor aging and impacting functional safety. Therefore, effectively reducing excessive motor operating temperatures remains an unresolved issue.

[0003] At present, the driving motor mainly adopts water cooling, oil cooling or air cooling to cool down. At the same time, the rotor is also assisted in cooling down by changing the structure of the rotor assembly. Chinese patent CN112636501B discloses a motor rotor and a motor, wherein the first balancing disk and the second balancing disk of the motor rotor are respectively fixed to the two ends of the rotor core and are coaxially arranged with the rotor core. The first balancing disk has a plurality of first weight-reducing holes, the second balancing disk has a plurality of second weight-reducing holes, and the rotor core has a plurality of third weight-reducing holes. The third weight-reducing holes are connected to the first weight-reducing holes and / or the second weight-reducing holes to form a stepped cooling channel. However, the balancing disk of the motor rotor cannot axially fix the magnets in the rotor core, and the balancing disk is relatively small. When the rotor assembly cannot reach dynamic balance due to work tolerance, it is not easy to set balancing holes on the balancing disk, which is not conducive to the dynamic balance of the motor rotor. Chinese patent CN113809855A discloses a rotor structure with multiple pressure differential generating components, including a rotating shaft, a rotor body, a first pressure differential generating component including multiple first pressure differential generating blocks, and a second pressure differential generating component including multiple second pressure differential generating blocks. The first average width of the first pressure differential generating block has a first trend change in an extension direction, and the second average width of the second pressure differential generating block has a second trend change in the extension direction. The first pressure differential generating block generates at least two first airflows, which flow from the first pressure differential generating component to the second pressure differential generating component. The second pressure differential generating block generates at least one second airflow, which flows from the second pressure differential generating component to the first pressure differential generating component, thereby achieving two-way airflow circulation and thus achieving the effect of heat dissipation and cooling. The pressure differential generating component in this method is equivalent to the rotor end plate, but the structure of the pressure differential component is relatively complex, resulting in an increase in the production cost of the rotor end plate.

[0004] Therefore, it is necessary to propose a rotor assembly that can effectively reduce the operating temperature of the rotor assembly and has a simple rotor end plate structure.

[0005] Summary of the Invention

[0006] One of the purposes of the present invention is to provide a rotor assembly to solve the technical problems in the prior art that the temperature of the rotor assembly is too high during rotation and cannot be effectively cooled, as well as the complex structure of the rotor end plate; the second purpose is to provide a motor; and the third purpose is to provide a new energy vehicle.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a rotor assembly, comprising: a rotor core, a first rotor end plate, a second rotor end plate, and a motor shaft; the rotor core being coaxially fixed to the motor shaft; the first and second rotor end plates being respectively fixed at opposite ends of the rotor core and coaxially fixed to the motor shaft; the rotor core being provided with first ventilation holes symmetrically distributed along a first pitch circle of a first diameter; the first and second rotor end plates being provided with second and third ventilation holes symmetrically distributed along a second pitch circle of a second diameter; the third ventilation holes being distributed along a third pitch circle of a third diameter, the second diameter being larger than the first diameter, and the first diameter being larger than the third diameter; the first, second, and third ventilation holes forming an axially symmetrical stepped ventilation duct. In one embodiment of the present invention, the second radial centerline of the second ventilation hole of the first rotor end plate coincides with the first radial centerline of the first ventilation hole, and the third radial centerline of the third ventilation hole of the second rotor end plate coincides with the first radial centerline.

[0009] In one embodiment of the present invention, the second ventilation hole on the first rotor end plate is offset toward the outside of the motor shaft and blocks the first ventilation hole, the third ventilation hole on the first rotor end plate is offset toward the inside of the motor shaft and blocks the first ventilation hole, the second ventilation hole on the second rotor end plate is offset toward the outside of the motor shaft and partially blocks the first ventilation hole, and the third ventilation hole on the second rotor end plate is offset toward the inside of the motor shaft and partially blocks the first ventilation hole.

[0010] In one embodiment of the present invention, the stepped ventilation duct includes a first ventilation duct and a second ventilation duct, and the wind directions of the first ventilation duct and the second ventilation duct are opposite.

[0011] In one embodiment of the present invention, the rotor assembly further includes a fixing member for fixing the rotor core and the rotor end plate to the motor shaft, and the fixing member and the third ventilation hole neither intersect nor overlap.

[0012] In one embodiment of the present invention, the fixing member includes a first fixing member for fixing the rotor core and the first rotor end plate to the motor shaft, and a second fixing member for fixing the rotor core and the second rotor end plate to the motor shaft, and the first fixing member and the second fixing member are interference fit with the motor shaft.

[0013] In one embodiment of the present invention, one end of the motor shaft is a spline end, and the other end is a resolver end. The spline end is provided with a limiter for fixing the rotor core and the second rotor end plate to the motor shaft. The fixing member fixes the rotor core and the first rotor end plate to the motor shaft at the spline end. The fixing member and the motor shaft are interference fit, and the limiter neither intersects nor overlaps with the third ventilation hole.

[0014] In one embodiment of the present invention, a first axial hole is further provided on the rotor core, and a second axial hole is further provided on the first rotor end plate and the second rotor end plate. The rotor core is fixed to the motor shaft through the first axial hole, and the first rotor end plate and the second rotor end plate are respectively fixed to the two ends of the rotor core coaxially with the motor shaft through the second axial holes.

[0015] In one embodiment of the present invention, the first shaft hole and the motor shaft are interference fit, and the second shaft hole and the motor shaft are overfit.

[0016] In one embodiment of the present invention, the fourth diameter of the outer contour of the rotor core is equal to the fifth diameter of the outer contour of the rotor end plate.

[0017] In one embodiment of the present invention, the second ventilation holes and the third ventilation holes are alternately and evenly distributed on the first rotor end plate and the second rotor end plate.

[0018] In a second aspect, the present invention further provides an electric motor, comprising the rotor assembly as described in the first aspect.

[0019] In one embodiment of the present invention, the motor is cooled by water cooling, oil cooling or air cooling.

[0020] In a third aspect, the present invention further provides a new energy vehicle, comprising the rotor assembly as described in the first aspect, or the motor as described in the second aspect.

[0021] Beneficial effects of the present invention:

[0022] The rotor core is coaxially fixed to the motor shaft, and the first rotor end plate and the second rotor end plate are respectively fixed at both ends of the rotor core and coaxially fixed to the motor shaft. A stepped ventilation duct is formed through the second ventilation hole and the third ventilation hole on the first rotor end plate, the first ventilation hole on the rotor core, and the second ventilation hole and the third ventilation hole on the second rotor end plate. When the rotor assembly rotates, a pressure difference is generated, so that an air path can be formed in the channel, realizing self-circulation cooling of the rotor assembly to achieve a cooling effect. In addition, the two ventilation holes arranged on the first rotor end plate and the second rotor end plate form a multi-step stepped ventilation duct with different directions, so that when the rotor assembly rotates, the inside of the rotor assembly is ventilated left and right to enhance the cooling effect. Moreover, the first rotor end plate and the second rotor end plate are simultaneously fixed on the motor shaft and both ends of the rotor core, which not only can fix the magnetic steel in the rotor core, but also the structure of the first rotor end plate and the second rotor end plate is simple, which can save the production cost of the rotor end plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a cross-sectional view of a rotor assembly according to an exemplary embodiment of the present invention;

[0024] FIG2 is a schematic axial view of a rotor assembly according to an exemplary embodiment of the present invention;

[0025] FIG3 is another axial schematic diagram of a rotor assembly according to an exemplary embodiment of the present invention;

[0026] FIG4 is a schematic diagram of an axial side of a rotor core according to an exemplary embodiment of the present invention;

[0027] FIG5 is a schematic diagram of a first pitch circle shown in an exemplary embodiment of the present invention;

[0028] FIG6 is a schematic axial view of a first rotor end plate according to an exemplary embodiment of the present invention;

[0029] FIG7 is a schematic diagram of a second pitch circle and a third pitch circle shown in an exemplary embodiment of the present application;

[0030] FIG8 is a schematic diagram of a first radial centerline shown in an exemplary embodiment of the present invention;

[0031] FIG9 is a schematic diagram of a second radial centerline and a third radial centerline shown in an exemplary embodiment of the present application;

[0032] FIG10 is a left side view of a rotor assembly according to an exemplary embodiment of the present invention;

[0033] FIG11 is a right side view of a rotor assembly according to an exemplary embodiment of the present application;

[0034] FIG12 is a cross-sectional view of another rotor assembly according to an exemplary embodiment of the present invention;

[0035] FIG13 is a simulation diagram of air inlet and outlet of a first ventilation hole at one end of a rotor core shown in an exemplary embodiment of the present application;

[0036] FIG14 is a simulation diagram of ventilation through a stepped ventilation duct according to an exemplary embodiment of the present invention;

[0037] Among them, 1-rotor core; 11-first ventilation hole; 12-first axial hole; 2-first rotor end plate; 21-first ventilation hole; 22-second ventilation hole; 23-second axial hole; 3-second rotor end plate; 4-motor shaft; 41-limiting part; 5-stepped ventilation duct; 6-fixing part. DETAILED DESCRIPTION

[0038] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following examples and the features in the examples can be combined with each other unless they conflict. It should also be understood that the terms used in the examples of the present invention are for the purpose of describing specific embodiments, not for the purpose of limiting the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0039] Please refer to Figures 1 to 14. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in this specification for people familiar with this technology to understand and read. They are not used to limit the conditions for the implementation of the present invention and therefore have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose of the present invention. At the same time, terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be considered as the scope of the implementation of the present invention without substantially changing the technical content.

[0040] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those in the examples of the present invention may also be used to implement the present invention.

[0041] The drive motor is one of the core components of the electric drive assembly of new energy vehicles. It includes a housing, stator core, rotor core, windings, permanent magnets, a rotating shaft, rotor end plates, and a pressure ring. During motor operation, the stator and rotor cores are exposed to an alternating magnetic field, generating iron losses. The windings generate copper losses when energized. Furthermore, the stator and rotor cores and permanent magnets generate hysteresis losses and eddy current losses. These losses can cause the motor to overheat during operation, accelerating motor aging and affecting motor functional safety. Therefore, effectively reducing the excessive operating temperature of the motor remains an unresolved issue. Currently, drive motors are primarily cooled by water, oil, or air. Additionally, modifications to the rotor assembly structure are used to assist in cooling the rotor. Research by the inventors and applicants has revealed that some motor rotors utilize a first balancing disc and a second balancing disc, each secured to each end of the rotor core and coaxially arranged with the rotor core. The first balancing disc has multiple first lightening holes, the second balancing disc has multiple second lightening holes, and the rotor core has multiple third lightening holes, which communicate with the first and / or second lightening holes to form a stepped cooling channel. However, the balancing discs of such motor rotors are unable to axially secure the magnets in the rotor core, and the balancing discs are relatively small. This makes it difficult to provide balancing holes on the discs when the rotor assembly cannot achieve dynamic balance due to work tolerances, hindering dynamic balancing of the motor rotor. Some rotor assemblies are composed of a first pressure differential generating assembly comprising a plurality of first pressure differential generating blocks and a second pressure differential generating assembly comprising a plurality of second pressure differential generating blocks. The first average width of the first pressure differential generating block has a first trend change in an extension direction, and the second average width of the second pressure differential generating block has a second trend change in the extension direction. The first pressure differential generating block generates at least two first airflows, which flow from the first pressure differential generating assembly to the second pressure differential generating assembly. The second pressure differential generating block generates at least one second airflow, which flows from the second pressure differential generating assembly to the first pressure differential generating assembly, thereby achieving two-way airflow circulation and heat dissipation and cooling. The pressure differential generating assembly in this method is equivalent to a rotor end plate, but its structure is relatively complex, resulting in increased manufacturing costs. Therefore, it is necessary to propose a rotor assembly that can effectively reduce the operating temperature of the rotor assembly and has a simple rotor end plate structure.

[0042] It should be noted that in the rotor assembly provided by the present invention, the number of first ventilation holes, second ventilation holes, and third ventilation holes is multiple and even. Furthermore, the number of second ventilation holes and third ventilation holes is the same, and the sum of the number of the second ventilation holes and third ventilation holes is the same as the number of first ventilation holes. The following figures all use an example in which the number of first ventilation holes is 8 and the number of second and third ventilation holes is 4. However, the number of first ventilation holes is not limited to 8, and the number of second and third ventilation holes is not limited to 4.

[0043] Referring to Figure 1 , the present invention provides a rotor assembly. Figure 1 is a cross-sectional view of a rotor assembly according to an exemplary embodiment of the present invention. As shown in Figure 1 , the rotor assembly comprises at least a rotor core 1, a first rotor end plate 2, a second rotor end plate 3, and a motor shaft 4. The rotor core 1 is coaxially fixed to the motor shaft 4. The first and second rotor end plates 2 and 3 are respectively fixed at opposite ends of the rotor core 1 and coaxially fixed to the motor shaft 4. Axisymmetrically distributed stepped ventilation ducts 5 are formed by the first, second, and third ventilation holes 11, 21, and 31.

[0044] Please refer to Figures 2-3. Figure 2 is a schematic axial view of a rotor assembly according to an exemplary embodiment of the present invention, and Figure 3 is another schematic axial view of the rotor assembly according to an exemplary embodiment of the present invention. As shown in Figures 2 and 3, the rotor assembly comprises at least a rotor core 1, a first rotor end plate 2, a second rotor end plate 3, and a motor shaft 4. The rotor core 1 is coaxially fixed to the motor shaft 4, and the first rotor end plate 2 and the second rotor end plate 3 are respectively fixed to the ends of the rotor core 1 and coaxially fixed to the motor shaft 4.

[0045] Please refer to Figures 4-7, wherein Figure 4 is an axially oriented schematic diagram of a rotor core according to an exemplary embodiment of the present invention, Figure 5 is a schematic diagram of a first pitch circle according to an exemplary embodiment of the present invention, Figure 6 is an axially oriented schematic diagram of a first rotor end plate according to an exemplary embodiment of the present invention, and Figure 7 is a schematic diagram of a second pitch circle and a third pitch circle according to an exemplary embodiment of the present application. As shown in Figure 4, the rotor core 1 is provided with first ventilation holes 11 distributed axially symmetrically, evenly distributed on a first pitch circle of a first diameter. The first pitch circle is a circle with the center point of the first axial hole 12 of the rotor core 1 as its center and the distance from the center point of the first ventilation hole 11 as its radius. Please refer to Figure 5 for details. As shown in Figure 6 , the first rotor end plate 2 is provided with second ventilation holes 21 and third ventilation holes 22, each axially symmetrically distributed. The second ventilation holes 21 are evenly distributed on a second pitch circle of a second diameter, while the third ventilation holes 22 are distributed on a third pitch circle of a third diameter. The second pitch circle is a circle with a center point of the second axial hole 23 of the first rotor end plate 2 and a radius equal to the distance from the center point of the second ventilation hole 21. The third pitch circle is a circle with a center point of the second axial hole 23 of the first rotor end plate 2 and a radius equal to the distance from the center point of the third ventilation hole 22. For details, please refer to Figure 7 . Since the first and second rotor end plates 2 and 3 have the same structure, the structure of the second rotor end plate will not be described in detail here.

[0046] It should be noted that the shapes of the first ventilation hole 11, the second ventilation hole 21 and the third ventilation hole 22 are not restricted in this application, but the second diameter corresponding to the second pitch circle is larger than the first diameter corresponding to the first pitch circle, and the first diameter corresponding to the first pitch circle is larger than the third diameter of the third pitch circle, so as to limit the positions of the first ventilation hole 11, the second ventilation hole 21 and the third ventilation hole 22, that is, the position of the second ventilation hole 21 is based on the motor shaft 4, and is located outside the first ventilation hole 11, and the position of the third ventilation hole 22 is based on the motor shaft 4, and is located inside the first ventilation hole 11. Therefore, the design principle of the size of the second ventilation hole 21 and the third ventilation hole 22 is that they can partially block the first ventilation hole 11 based on the size relationship between the first diameter, the second diameter and the third diameter.

[0047] In an embodiment of the present application, the rotor core is coaxially fixed to the motor shaft, and the first rotor end plate and the second rotor end plate are respectively fixed at both ends of the rotor core and coaxially fixed to the motor shaft. A stepped ventilation duct is formed by the second ventilation hole and the third ventilation hole on the first rotor end plate, the first ventilation hole on the rotor core, and the second ventilation hole and the third ventilation hole on the second rotor end plate. When the rotor assembly rotates, a pressure difference is generated, so that an air path can be formed in the channel, realizing self-circulation cooling of the rotor assembly and achieving a cooling effect. In addition, the two types of ventilation holes arranged on the first rotor end plate and the second rotor end plate form a multi-step stepped ventilation duct with different directions, so that when the rotor assembly rotates, the inside of the rotor assembly is ventilated left and right, enhancing the cooling effect. Moreover, the first rotor end plate and the second rotor end plate are simultaneously fixed to the motor shaft and both ends of the rotor core, which not only can fix the magnetic steel in the rotor core, but the structure of the first rotor end plate and the second rotor end plate is also simple and firm, which can save the manufacturing cost of the rotor end plate.

[0048] Furthermore, the entire rotor assembly is heavy and has a large moment of inertia, resulting in significant losses during motor operation and difficulty significantly improving efficiency. Furthermore, the heavy rotor assembly results in poor motor stability and high noise levels during assembly. As key motor components, the rotor core and rotor end plates are hollowed out. The first, second, and third ventilation holes not only form stepped ventilation ducts that ventilate and cool the rotor assembly, but also reduce weight, making the entire rotor assembly lightweight.

[0049] In one embodiment, when the first rotor end plate 2 and the second rotor end plate 3 are arranged at both ends of the rotor core 1, the second radial center line of the second ventilation hole 21 of the first rotor end plate 2 coincides with the first radial center line of the first ventilation hole 11, and the third radial center line of the third ventilation hole 22 of the second rotor end plate 3 coincides with the first radial center line.

[0050] Please refer to Figures 8 and 9. Figure 8 is a schematic diagram of a first radial centerline according to an exemplary embodiment of the present invention, and Figure 9 is a schematic diagram of a second radial centerline and a third radial centerline according to an exemplary embodiment of the present application. As shown in Figure 8, the first radial centerline L1 is a straight line connecting the center point of one of the first ventilation holes 11 and the center point of the first axial hole 12; as shown in Figure 9, the second radial centerline L2 is a straight line connecting the center point of one of the second ventilation holes 21 and the center point of the second axial hole 23; and the third radial centerline L3 is a straight line connecting the center point of one of the third ventilation holes 22 and the center point of the second axial hole 23.

[0051] In the embodiment of the present application, by aligning the second radial center line of the second ventilation hole 21 of the first rotor end plate 2 with the first radial center line of the first ventilation hole 11, and aligning the third radial center line of the third ventilation hole 22 of the second rotor end plate 3 with the first radial center line, the second rotor end plate 3 is rotated clockwise or counterclockwise by a certain angle relative to the first rotor end plate 2. The angle is the same as the angle formed by the center points of the adjacent first ventilation holes 21 and the second ventilation holes 22 relative to the center point of the second axial hole 23, thereby forming a stepped ventilation duct 5.

[0052] For example, taking the example of four first ventilation holes 21 and four second ventilation holes 22, the first ventilation holes 21 and the second ventilation holes 22 are evenly and alternately distributed on the second pitch circle and the third pitch circle. At this time, the angle formed by the center point of the adjacent first ventilation hole 21 and the center point of the second ventilation hole 22 relative to the center point of the second axial hole 23 is 45°. Then, the second rotor end plate 3 is rotated 45° clockwise or counterclockwise relative to the first rotor end plate 2.

[0053] Please refer to Figures 10 and 11. In one embodiment, Figure 10 is a left view of a rotor assembly according to an exemplary embodiment of the present invention, and Figure 11 is a right view of a rotor assembly according to an exemplary embodiment of the present application. As shown in Figure 10, the second ventilation hole 21 on the first rotor end plate 2 is offset outward from the motor shaft 4, blocking the first ventilation hole 11, and the third ventilation hole 22 on the first rotor end plate 2 is offset inward from the motor shaft 4, blocking the first ventilation hole 11. As shown in Figure 11, the second ventilation hole 21 on the second rotor end plate 3 is offset outward from the motor shaft 4, partially blocking the first ventilation hole, and the third ventilation hole 22 on the second rotor end plate 3 is offset inward from the motor shaft 4, partially blocking the first ventilation hole 11.

[0054] In the embodiment of the present application, a stepped ventilation duct 5 is formed by staggering the first ventilation hole 11 and the second ventilation holes 21 and the third ventilation holes 22 in different directions. Preferably, the second ventilation holes 21 and the third ventilation holes 22 each block half of the first ventilation hole 11, thereby ensuring equal inlet and outlet air volumes and avoiding the situation where, when the inlet and outlet air volumes are unbalanced, part of the wind will form vortices at the air outlets at both ends or in the ventilation duct of the rotor core 1, thereby affecting the flow of wind speed.

[0055] In one embodiment, the stepped ventilation duct 5 includes a first ventilation duct and a second ventilation duct, and the wind directions of the first ventilation duct and the second ventilation duct are opposite.

[0056] Please continue to refer to Figure 1. As shown in Figure 1, when viewed from left to right, the stepped direction of the stepped channel 5 is such that an airflow from the motor shaft 4 to the outside is formed in the stepped ventilation duct 5 through the third ventilation hole 22 on the second rotor end plate 3, the first ventilation hole 11 on the rotor core 1, and the second ventilation hole 21 on the first rotor end plate 2.

[0057] Please refer to Figure 12, which is a cross-sectional view of another rotor assembly according to an exemplary embodiment of the present invention. As shown in Figure 12, still viewed from left to right, the steps of the stepped passage 5 extend inward from the motor shaft 4 through the second ventilation holes 21 on the second rotor end plate 3, the first ventilation holes 11 on the rotor core 1, and the third ventilation holes 22 on the first rotor end plate 2, forming a right-to-left airflow path within the stepped ventilation passage 5.

[0058] In the embodiment of the present application, the stepped ventilation ducts 5 in two directions are alternately and evenly distributed, so that when the rotor assembly rotates, the inside of the rotor assembly is ventilated left and right, which can enhance the cooling effect.

[0059] Continuing to refer to FIG. 12 , in one embodiment, the rotor assembly further includes a fixing member 6 for fixing the rotor core 1 and the rotor end plate to the motor shaft 4 . The fixing member 6 and the third ventilation hole 22 neither intersect nor overlap.

[0060] In an embodiment of the present application, the fixing member 6 can be a structural member with a fixing function, such as a pressure ring and a locking nut, which can further fix the rotor core 1 and the rotor end plate on the motor shaft 4, so that the overall structure of the rotor assembly is more fixed and compact. In addition, the size of the fixing member 6 will not block the third ventilation hole 22 and will not affect the ventilation effect of the stepped ventilation duct 5.

[0061] Taking into account the different structures of the motor shaft itself, as a possible embodiment, the fixing member 6 may include a first fixing member for fixing the rotor core 1 and the first rotor end plate 2 on the motor shaft 4, and a second fixing member for fixing the rotor core 1 and the second rotor end plate 3 on the motor shaft 4, and the first fixing member and the second fixing member are interference fit with the motor shaft 4.

[0062] Please continue to refer to Figure 12, as another possible embodiment, the left end of the motor shaft 4 is a spline end, and the right end is a resolver end. A limiter 41 is provided at the spline end to fix the rotor core 1 and the second rotor end plate 3 on the motor shaft 4. The fixing member 6 fixes the rotor core 1 and the first rotor end plate 2 on the motor shaft 4 at the spline end. The fixing member 6 and the motor shaft 4 are interference fit, and the limiter 41 and the third ventilation hole 22 neither intersect nor overlap.

[0063] It should be noted that the interference fit utilizes the elasticity of the material to expand and deform the hole so that it fits over the shaft. When the hole is restored, a clamping force is generated on the shaft, connecting the two parts. The connection structure is simple and can withstand torque, axial force, or a combination of the two. It also has a high load-bearing capacity and can operate reliably under impact and vibration loads. The first and second fixing members and the motor shaft, as well as the fixing member 6 and the motor shaft 4, are interference fits, which can ensure that their fixation is more reliable. In addition, the size of the limiter 41 does not block the third ventilation hole 22 and does not affect the ventilation effect of the stepped ventilation duct 5.

[0064] In one embodiment, the first shaft hole 12 and the motor shaft 4 are interference fit, and the second shaft hole 23 and the motor shaft 4 are overfit.

[0065] It should be noted that, depending on the fixing characteristics between the first axial hole 12 and the motor shaft 4, and the fixing characteristics between the second axial hole 23 and the motor shaft 4, different connection and fixation principles are used. Among them, an interference fit refers to a fit in which the tolerance zone of the hole is located below the tolerance zone of the shaft, with an interference fit (including a minimum interference of zero). That is, relying on the interference value of the shaft and the hole, elastic pressure is generated between the surfaces of the parts after assembly, thereby obtaining a tight connection. A transition fit refers to a fit in which the tolerance zone of the hole overlaps the tolerance zone of the shaft, and may have a gap or interference fit. It is used for relatively static connections that require precise positioning and disassembly, and is easy to disassemble and assemble.

[0066] Continuing to refer to FIG. 12 , in one embodiment, the fourth diameter of the outer contour of the rotor core 1 is equal to the fifth diameter of the outer contour of the rotor end plate.

[0067] In the embodiment of the present application, in order to enable the first and second rotor end plates 2 and 3 to secure the magnets in the rotor core 1, the first and second rotor end plates 2 and 3 are sized to overlap and secure the ends of the rotor core 1. Since both the first and second rotor end plates 1 and 3 are provided with two types of ventilation holes, this reduces weight without affecting the weight of the entire rotor assembly. It should be noted that the fourth diameter of the outer contour of the rotor core 1 may be greater than the fifth diameter of the outer contour of the rotor end plates, but this does not affect the effectiveness of the first and second rotor end plates 2 and 3 in securing the magnets in the rotor core 1.

[0068] In another embodiment of the present application, when the motor rotor is rotating, imbalance may occur due to working tolerances. Since the first rotor end plate 2 and the second rotor end plate 3 are relatively large, in addition to the first ventilation holes 21 and the second ventilation holes 22 that can be set on the first rotor end plate 2 and the second rotor end plate 3, dynamic balancing holes can also be set on the first rotor end plate 2 and / or the second rotor end plate 3 according to the specific imbalance situation to ensure dynamic balance during the rotation of the rotor assembly.

[0069] 10 and 11 , in one embodiment, the second ventilation holes 21 and the third ventilation holes 23 are alternately and evenly distributed on the first rotor end plate 2 and the second rotor end plate 3 .

[0070] In the embodiment of the present application, the second ventilation holes 21 and the third ventilation holes 23 are alternately and evenly distributed, so that the first ventilation duct and the second ventilation duct in the stepped ventilation duct 5 are alternately and evenly distributed, so that the weight of the entire rotor assembly is evenly distributed, and when the rotor assembly rotates, the rotation of the entire rotor assembly can achieve balance.

[0071] In summary, as a possible implementation method, the rotor core can be designed with 8 first ventilation holes, which are evenly distributed on the first pitch circle of D1=Φ90. The first rotor end plate and the second rotor end plate can be designed with 4 second ventilation holes with a diameter of d1=Φ16 and 4 third ventilation holes with a diameter of d2=Φ14, which are alternately and evenly distributed. The second ventilation holes are evenly distributed on the second pitch circle of D2=Φ102, and the third ventilation holes are evenly distributed on the third pitch circle of D3=Φ79, finally forming 8 stepped ventilation ducts, wherein the third ventilation holes with a diameter of d2=Φ14 take in air, and the second ventilation holes with a diameter of d1=Φ16 discharge air.

[0072] After CFD (Computational Fluid Dynamics) analysis, the stepped ventilation duct 5 is capable of forming an air path. Please refer to Figure 13, which is a simulation diagram of the air inlet and outlet of the first ventilation holes at one end of the rotor core shown in an exemplary embodiment of the present application. As shown in Figure 13, 4 of the 8 first ventilation holes are used for air intake and 4 are used for air outlet, forming 8 first ventilation holes that alternately inlet and outlet air. Among them, the inlet and outlet air have a certain wind speed, and the mass flow rate and mass volume flow rate of the air volume can be shown in Table 1:

[0073] Table 1: Mass flow and volume flow of air

[0074] In Table 1, the constraint plane section can be understood as the end face of the stepped ventilation duct inlet and outlet, as shown in Figure 10. Starting from any third ventilation hole 22, they are numbered clockwise, that is, they correspond to the constraint plane sections 1 to 8 in the table. It should be noted that the third ventilation hole 22 is the air inlet and the second ventilation hole 21 is the air outlet. It can be seen from Table 1 that the four third ventilation holes 22 correspond to the constraint plane sections 1, 3, 5, and 7 respectively, and the four second ventilation holes 21 correspond to the constraint plane sections 2, 4, 6, and 8 respectively. At this time, the air intake of the air inlet is greater than the air outlet of the air outlet.

[0075] It should be understood that when the second ventilation hole 21 and the third ventilation hole 22 both block half of the first ventilation hole 11, it is an optimal way. At this time, the overall mass flow rate and volume flow rate of the outgoing air and the incoming air can reach a close situation respectively, ensuring the same inlet and outlet air volume, avoiding the formation of vortexes in the ventilation duct and affecting the flow of wind speed, thereby ensuring the cooling effect.

[0076] In addition, please refer to Figure 14, which is a simulation diagram of ventilation in a stepped ventilation duct according to an exemplary embodiment of the present invention. As shown in Figure 14, the wind direction is from the third ventilation hole to the first ventilation hole and then to the second ventilation hole, achieving wind flow.

[0077] In summary, the present invention provides a rotor assembly, which coaxially fixes the rotor core on the motor shaft, and the first rotor end plate and the second rotor end plate are respectively fixed at both ends of the rotor core and coaxially fixed with the motor shaft. A stepped ventilation duct is formed through the second ventilation hole and the third ventilation hole on the first rotor end plate, the first ventilation hole of the rotor core, and the second ventilation hole and the third ventilation hole on the second rotor end plate. When the rotor assembly rotates, a pressure difference is generated, so that an air path can be formed in the channel, realizing self-circulation cooling of the rotor assembly and achieving a cooling effect. In addition, the two ventilation holes arranged on the first rotor end plate and the second rotor end plate form a multi-step stepped ventilation duct with different directions, so that when the rotor assembly rotates, the inside of the rotor assembly is ventilated left and right, enhancing the cooling effect. Moreover, the first rotor end plate and the second rotor end plate are simultaneously fixed on the motor shaft and the two ends of the rotor core, which can fix the magnetic steel in the rotor core. The structure of the first rotor end plate and the second rotor end plate is simple and firm, which can save the production cost of the rotor assembly.

[0078] The present invention also provides a motor, comprising and using the rotor assembly as described above.

[0079] In one embodiment, the motor is cooled by water cooling, oil cooling or air cooling.

[0080] It should be noted that in addition to cooling the motor by water cooling, oil cooling or air cooling, the motor can also be assisted by cooling the rotor assembly. When the motor includes the rotor assembly provided in the above-mentioned real-time example, the cooling method of the motor is not limited, that is, the motor can still be cooled by water cooling, oil cooling or air cooling.

[0081] It should also be noted that the motor provided in the above embodiment and the rotor assembly provided in the above embodiment belong to the same concept, wherein each structure has been described in detail in the rotor assembly embodiment and will not be repeated here.

[0082] The present invention also provides a new energy vehicle, comprising the use of the rotor assembly as described above, or the use of the motor as described above.

[0083] It should be noted that the new energy vehicle provided in the above embodiment and the rotor assembly provided in the above embodiment belong to the same concept, wherein each structure has been described in detail in the rotor assembly embodiment and will not be repeated here.

[0084] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A rotor assembly, characterized in that: The rotor assembly comprises a rotor core, a first rotor end plate, a second rotor end plate and a motor shaft, wherein the rotor core is coaxially fixed to the motor shaft, and the first rotor end plate and the second rotor end plate are respectively fixed at two ends of the rotor core and coaxially fixed to the motor shaft; The rotor core is provided with first ventilation holes which are axially symmetrically distributed, and the first ventilation holes are distributed on a first pitch circle of a first diameter; The first rotor end plate and the second rotor end plate are provided with second ventilation holes and third ventilation holes respectively distributed in an axisymmetric manner, the second ventilation holes are distributed on a second pitch circle of a second diameter, and the third ventilation holes are distributed on a third pitch circle of a third diameter; The second diameter is greater than the first diameter, the first diameter is greater than the third diameter, and the first ventilation holes, the second ventilation holes, and the third ventilation holes form a stepped ventilation passage that is axially symmetrically distributed.

2. The rotor assembly according to claim 1, characterized in that: The second radial centerline of the second ventilation hole of the first rotor end plate coincides with the first radial centerline of the first ventilation hole, and the third radial centerline of the third ventilation hole of the second rotor end plate coincides with the first radial centerline.

3. The rotor assembly according to claim 2, characterized in that: The second ventilation hole on the first rotor end plate is offset toward the outside of the motor shaft and blocks the first ventilation hole, the third ventilation hole on the first rotor end plate is offset toward the inside of the motor shaft and blocks the first ventilation hole, the second ventilation hole on the second rotor end plate is offset toward the outside of the motor shaft and partially blocks the first ventilation hole, and the third ventilation hole on the second rotor end plate is offset toward the inside of the motor shaft and partially blocks the first ventilation hole.

4. The rotor assembly according to claim 1, characterized in that: The stepped ventilation passage comprises a first ventilation passage and a second ventilation passage, and the wind directions of the first ventilation passage and the second ventilation passage are opposite.

5. The rotor assembly according to claim 1, characterized in that: The rotor assembly also includes a fixing member for fixing the rotor core and the rotor end plate on the motor shaft, and the fixing member and the third ventilation hole neither intersect nor overlap.

6. The rotor assembly according to claim 5, characterized in that: The fixing member includes a first fixing member for fixing the rotor core and the first rotor end plate on the motor shaft, and a second fixing member for fixing the rotor core and the second rotor end plate on the motor shaft, and the first fixing member and the second fixing member are interference fit with the motor shaft.

7. The rotor assembly according to claim 5, characterized in that: One end of the motor shaft is a spline end, and the other end is a resolver end. The spline end is provided with a limiter for fixing the rotor core and the second rotor end plate on the motor shaft. The fixing member fixes the rotor core and the first rotor end plate on the motor shaft at the spline end. The fixing member and the motor shaft are interference fit, and the limiter neither crosses nor overlaps with the third ventilation hole.

8. The rotor assembly according to claim 1, characterized in that: The rotor core is also provided with a first axial hole, and the first rotor end plate and the second rotor end plate are also provided with a second axial hole. The rotor core is fixed to the motor shaft through the first axial hole, and the first rotor end plate and the second rotor end plate are respectively fixed to the two ends of the rotor core coaxially with the motor shaft through the second axial hole.

9. The rotor assembly according to claim 8, characterized in that: The first shaft hole and the motor shaft are interference fit, and the second shaft hole and the motor shaft are overfit.

10. The rotor assembly according to claim 1, characterized in that: The fourth diameter of the outer contour of the rotor core is equal to the fifth diameter of the outer contour of the rotor end plate.

11. The rotor assembly according to claim 1, characterized in that: The second ventilation holes and the third ventilation holes are alternately and evenly distributed on the first rotor end plate and the second rotor end plate.

12. A motor, characterized in that: Comprising the use of a rotor assembly as claimed in any one of claims 1 to 11.

13. The motor according to claim 12, characterized in that The motor is cooled by water cooling, oil cooling or air cooling.

14. A new energy vehicle, characterized in that: The method comprises using the rotor assembly according to any one of claims 1 to 11, or using the motor according to any one of claims 12 to 13.

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