Rotor assembly and motor

Abstract

The invention provides a rotor assembly and a motor, the rotor assembly comprises a rotating shaft, magnetic steel and a sheath, the magnetic steel is arranged at the periphery of a part of a shaft section of the rotating shaft, at least part of the sheath sleeves the periphery of the magnetic steel, the sheath comprises a first sheath and a second sheath, the first sheath is located at the periphery of the second sheath, and the second sheath is located at the periphery of the first sheath. The first sheath and the second sheath are arranged in a spaced mode, so that a cooling channel allowing fluid to flow is formed between the first sheath and the second sheath, and airflow flowing in the cooling channel can flow through the shaft end of the magnetic steel so as to cool and dissipate heat of the magnetic steel. According to the invention, the cooling and heat dissipation effects of the magnetic steel of the surface-mounted magnetic steel rotor can be improved, the heat dissipation efficiency of the rotor structure of the surface-mounted permanent magnet synchronous motor is improved, and the demagnetization risk of the magnetic steel of the rotor is reduced; the rotor structure effectively solves the problem that a rotor structure of a surface-mounted permanent magnet synchronous high-speed motor in the prior art is low in heat dissipation efficiency.

Description

TECHNICAL FIELD

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

[0002] High-speed electric machines have broad application prospects in aerospace, rail transit, electric vehicles, industrial servo systems, and new energy power generation due to their high rotational speed, high power density, and high efficiency characteristics. However, during high-speed operation, the superimposed effects of electromagnetic losses, eddy current losses, and mechanical losses within the electric machine result in concentrated heat generation, and the temperature control of the rotor magnet steel area becomes a core bottleneck restricting the performance improvement and long-term reliability of the electric machine. As the rotational speed continues to rise and the power density continues to increase, the rotor magnet steel faces severe thermal management challenges: the centrifugal force generated by high-speed rotation exacerbates the heat flow density, and the compactness and dynamic rotation characteristics of the rotor structure further restrict the efficient dissipation of heat, leading to local overheating of the magnet steel, increased demagnetization risk, and ultimately causing the electric machine to decrease in efficiency, shorten in lifespan, and even fail.

[0003] In existing cooling technologies, air cooling systems have been used for overall heat dissipation of electric machines for a long time due to their simple structure, low cost, and convenient maintenance. However, traditional air cooling systems have significant defects in rotor-specific cooling. The core problem is that: Although researchers have attempted to improve air cooling systems through airflow channel reconstruction or intelligent control strategies, these solutions are all focused on optimizing rotor cooling for built-in rotors. Existing technologies cannot achieve efficient and uniform cooling of surface-mounted rotor magnet steel, and cannot simultaneously consider heat exchange stability under high-speed operating conditions, making rotor temperature rise a primary constraint on the evolution of high-performance electric machines.

[0004] In traditional electric machine air cooling technology, cooling air enters the electric machine cavity through the air inlet and flows out through the air outlet. In the process, it flows through the stator winding and the air gap between the stator and the rotor, and exchanges heat with the electric machine to control the temperature rise. However, this cooling air cannot exchange heat with the rotor sheath and magnet steel. For surface-mounted permanent magnet synchronous high-speed electric machines, high rotational speed results in extremely high electrical frequency for the rotor, which causes significant eddy current loss in the rotor sheath and magnet steel, leading to temperature rise in the rotor sheath and magnet steel. However, the thermal conductivity of the alloy sheath cannot satisfy the requirement of transferring all the heat generated inside the magnet steel and sheath to the stator-rotor air gap for heat exchange and cooling with the air cooling system. Therefore, the rotor temperature of a surface-mounted high-speed electric machine rises more significantly than other types of electric machines, increasing the risk of demagnetization of the rotor magnet steel.

[0005] Due to the low heat dissipation efficiency of the rotor structure of the surface-mounted permanent magnet synchronous high-speed electric machine in the prior art, a rotor assembly and an electric machine are designed. SUMMARY

[0006] Therefore, the technical problem to be solved by the present application is to overcome the low heat dissipation efficiency of the rotor structure of the surface-mounted permanent magnet synchronous high-speed motor in the prior art, so as to provide a rotor assembly and a motor.

[0007] In order to solve the above problems, the present application provides a rotor assembly, which comprises: a rotating shaft, a magnetic steel and a sheath, the magnetic steel is arranged on the outer periphery of a part of the shaft section of the rotating shaft, at least part of the sheath is sleeved on the outer periphery of the magnetic steel, and the sheath comprises a first sheath and a second sheath, the first sheath is located on the outer periphery of the second sheath, and the first sheath is arranged in a spaced manner with the second sheath, so that a cooling channel allowing fluid flow is formed between the first sheath and the second sheath, and the airflow flowing through the cooling channel can flow to the shaft end of the magnetic steel to cool and dissipate heat of the magnetic steel.

[0008] In some embodiments, the rotating shaft comprises a magnetic steel assembly section and a first sheath assembly section, the first sheath assembly section is connected to the magnetic steel assembly section along the axial direction of the rotating shaft, the outer diameter of the magnetic steel assembly section is smaller than the outer diameter of the first sheath assembly section, so that a first step surface is formed at the connection position of the two, the first sheath assembly section is located upstream of the magnetic steel assembly section along the flow direction of the cooling airflow, the magnetic steel is arranged on the outer periphery of the magnetic steel assembly section, and the outer periphery of the magnetic steel is arranged protruding from the outer periphery of the first sheath assembly section, so that the airflow can flow to the shaft end surface of the magnetic steel to exchange heat with the magnetic steel.

[0009] In some embodiments, the rotating shaft further comprises a second sheath assembly section, the outer diameter of the magnetic steel assembly section is also smaller than the outer diameter of the second sheath assembly section, so that a second step surface is formed at the connection position of the two, the first sheath assembly section, the magnetic steel assembly section and the second sheath assembly section are connected in sequence along the axial direction of the rotating shaft, the second sheath assembly section is located downstream of the magnetic steel assembly section along the flow direction of the cooling airflow, part of the shaft section of the second sheath is located on the outer periphery of the magnetic steel, part of the shaft section is located on the outer periphery of the first sheath assembly section, and part of the shaft section is located on the outer periphery of the second sheath assembly section.

[0010] In some embodiments, the magnetic steel is a plurality of magnetic steels, and the plurality of magnetic steels are arranged in sequence along the circumferential direction of the magnetic steel assembly section; and / or the magnetic steel is a plurality of magnetic steels, and the plurality of magnetic steels are arranged in sequence along the axial direction of the magnetic steel assembly section.

[0011] In some embodiments, The magnetic steel is an arc-shaped ring structure, comprising a magnetic steel outer surface at the outer periphery thereof, a magnetic steel assembly surface at the inner periphery thereof, magnetic steel shaft end surfaces at the axial ends thereof, and magnetic steel circumferential end surfaces at the circumferential sides thereof; two or more magnetic steels are spliced along the circumferential direction of the magnetic steel assembly section to form a circular ring structure.

[0012] In some embodiments, The second sheath comprises a magnetic steel sheath section and a first shaft sheath section, at least part of the structure of the magnetic steel sheath section is located at the outer periphery of the magnetic steel, the first shaft sheath section is located at the outer periphery of the first sheath assembly section, and the magnetic steel sheath section and the first shaft sheath section are both ring structures, the inner diameter of the magnetic steel sheath section is greater than the outer diameter of the first shaft sheath section, the outer diameter of the magnetic steel is greater than the outer diameter of the first shaft sheath section, the first shaft sheath section and the first sheath are spaced apart to form a first cooling channel, the cooling channel comprises the first cooling channel, and the first cooling channel is opposite to the shaft end surface of the magnetic steel, so that the fluid flowing in the first cooling channel can reach the shaft end surface of the magnetic steel to cool the magnetic steel.

[0013] In some embodiments, The magnetic steel sheath section and the first shaft sheath section are spaced apart in the axial direction of the shaft to form a first spacing channel allowing gas flow, the magnetic steel sheath section and the first sheath are spaced apart to form a second cooling channel, the cooling channel comprises the second cooling channel, the first cooling channel, the first spacing channel, and the second cooling channel are sequentially communicated, the first cooling channel is upstream of the second cooling channel in the gas flow direction, and part of the structure of the magnetic steel can extend into the first spacing channel, so that the shaft end surface and the circumferential end surface of the magnetic steel in the first spacing channel can be cooled by the gas.

[0014] In some embodiments, The second sheath further comprises a second shaft sheath section, when the shaft further comprises a second sheath assembly section, the second shaft sheath section is located at the outer periphery of the second sheath assembly section, and the second shaft sheath section is a ring structure, the inner diameter of the magnetic steel sheath section is greater than the outer diameter of the second shaft sheath section, the outer diameter of the magnetic steel is greater than the outer diameter of the second shaft sheath section, the second shaft sheath section and the first sheath are spaced apart to form a third cooling channel, the cooling channel comprises the third cooling channel, the third cooling channel is opposite to the shaft end surface of the magnetic steel, so that the fluid flowing in the second cooling channel can reach the shaft end surface of the magnetic steel to cool the magnetic steel.

[0015] In some embodiments, The magnetic steel sleeve segment and the second shaft sleeve segment are arranged in the axial direction of the shaft to form a second interval channel allowing airflow to pass through, the second cooling channel, the second interval channel and the third cooling channel are sequentially communicated, and part of the structure of the magnetic steel can extend into the second interval channel, so that the axial end face and the circumferential end face of the magnetic steel located in the second interval channel can be cooled by the gas.

[0016] In some embodiments, The inner periphery of the magnetic steel sleeve segment is in abutment and interference with the outer peripheral surface of the magnetic steel, the first shaft sleeve segment is in abutment and interference with the outer peripheral surface of the first sleeve assembly segment, and the second shaft sleeve segment is in abutment and interference with the outer peripheral surface of the second sleeve assembly segment.

[0017] In some embodiments, The first shaft sleeve segment and the first sleeve further have a first support part, and the first support part has at least two, and the at least two first support parts are arranged in the circumferential direction of the shaft to form the first cooling channel between adjacent first support parts. The second shaft sleeve segment and the first sleeve further have a third support part, and the third support part has at least two, and the at least two third support parts are arranged in the circumferential direction of the shaft to form the third cooling channel between adjacent third support parts.

[0018] In some embodiments, The magnetic steel sleeve segment and the first sleeve further have a second support part, and the second support part has at least two, and the at least two second support parts are arranged in the circumferential direction of the shaft to form the second cooling channel between adjacent second support parts. The at least two second support parts are further arranged in the axial direction of the shaft.

[0019] In some embodiments, When the shaft further includes a second sleeve assembly segment, the axial dimensions of the first sleeve assembly segment, the second sleeve assembly segment and the magnetic steel assembly segment in the axial direction of the shaft are L, the axial dimension of the first shaft sleeve segment is Lb, the axial dimension of the second shaft sleeve segment is Lb, the axial dimension of the magnetic steel sleeve segment is La, and L≥La+2Lb.

[0020] The application further provides an electric machine comprising the aforementioned rotor assembly.

[0021] The rotor assembly and the electric machine provided by the application have the following beneficial effects: 1. The present application sets the sheath of the surface-mounted magnetic steel rotor to include a first sheath and a second sheath, and forms a cooling channel allowing fluid flow between the first sheath and the second sheath, and the cooling channel can flow through the shaft end of the magnetic steel to cool and dissipate heat from the magnetic steel. Compared with the prior art that can only cool the outer peripheral surface of the magnetic steel, the cooling fluid of the present application can also contact the shaft end surface of the magnetic steel, that is, it can also effectively cool and dissipate heat from the shaft end surface of the magnetic steel. Therefore, the cooling and heat dissipation effect of the magnetic steel of the surface-mounted magnetic steel rotor is effectively improved, the heat dissipation efficiency of the rotor structure of the surface-mounted permanent magnet synchronous motor is improved, and the demagnetization risk of the rotor magnetic steel is reduced. The problem of low heat dissipation efficiency of the rotor structure of the surface-mounted permanent magnet synchronous motor in the prior art is effectively solved.

[0022] 2. The present application further sets the first shaft sheath segment and the magnetic steel sheath segment apart to form a first interval channel, and the magnetic steel part structure extends into the first interval channel, thereby further cooling and dissipating heat from the shaft end surface and the circumferential end surface of the magnetic steel, further improving the cooling and heat dissipation performance of the magnetic steel, thereby further improving the heat dissipation efficiency of the rotor structure of the surface-mounted permanent magnet synchronous motor and reducing the demagnetization risk of the rotor magnetic steel. The present application further sets the second shaft sheath segment and the magnetic steel sheath segment apart to form a second interval channel, and the magnetic steel part structure extends into the second interval channel, thereby further cooling and dissipating heat from the shaft end surface and the circumferential end surface of the magnetic steel, further improving the cooling and heat dissipation performance of the magnetic steel, thereby further improving the heat dissipation efficiency of the rotor structure of the surface-mounted permanent magnet synchronous motor and reducing the demagnetization risk of the rotor magnetic steel. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is an exploded view of the rotor assembly of the present application; Figure 2 is a structural schematic view of the shaft part of Figure 1 Figure 3 is a perspective view of the sheath part in Figure 1 Figure 4 is a cross-sectional front view of Figure 3 Figure 5 is a side view of the assembled rotor assembly of Figure 1

[0024] The reference signs are as follows: ​​​​1, rotating shaft; 2, magnetic steel; 3, sheath; 4, first sheath; 5, second sheath; 6, cooling channel; 7, magnetic steel assembly section; 8, first sheath assembly section; 9, first step surface; 10, second sheath assembly section; 11, second step surface; 12, magnetic steel outer surface; 13, magnetic steel assembly surface; 14, magnetic steel shaft end surface; 15, magnetic steel peripheral end surface; 16, magnetic steel sheath section; 17, first rotating shaft sheath section; 18, first cooling channel; 19, first interval channel; 20, second cooling channel; 21, second rotating shaft sheath section; 22, third cooling channel; 23, second interval channel; 24, first support part; 25, second support part; 26, third support part. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not intended to limit the present application and its application or use in any way. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0026] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a reference to the presence of a feature, step, operation, device, component, and / or combinations thereof.

[0027] Unless specifically stated otherwise, the relative arrangements of the components and steps illustrated in these embodiments and the numerical expressions and values set forth herein are not limiting. It should be understood that the various parts shown in the drawings are not necessarily drawn to scale in proportion. Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered as part of the authorized description. In all examples shown and discussed herein, any specific value should be interpreted as merely exemplary, and not as a limitation. Therefore, other examples of exemplary embodiments can have different values. It should be noted that similar reference numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0028] In the description of the application, it needs to be understood that the orientation words such as "front, back, up, down, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or positional relationship are generally based on the orientation or positional relationship shown in the drawings, only for the convenience of describing the application and simplifying the description, without the opposite statement, these orientation words do not indicate and imply that the device or element indicated must have a specific orientation or be constructed and operated in a specific orientation, therefore, it cannot be understood as a limitation on the protection scope of the application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0029] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper" and the like can be used herein to describe the spatial positional relationship of one device or feature with other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawings is inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0030] In addition, it needs to be pointed out that the use of "first", "second" and the like to define parts is only for the convenience of distinguishing the corresponding parts, and the above words have no special meaning unless otherwise stated, therefore, it cannot be understood as a limitation on the protection scope of the application.

[0031] As Figures 1-5 The application provides a rotor assembly (preferably a surface-mounted magnetic steel rotor assembly), which comprises: a rotating shaft 1, a magnetic steel 2 arranged on the outer periphery of a part of the shaft section of the rotating shaft 1, and a sheath 3, at least part of which is sleeved on the outer periphery of the magnetic steel 2, and the sheath 3 comprises a first sheath 4 and a second sheath 5, the first sheath 4 is located on the outer periphery of the second sheath 5, and the first sheath 4 and the second sheath 5 are arranged in a spaced manner, so that a cooling channel 6 allowing fluid flow is formed between the first sheath 4 and the second sheath 5, and the airflow flowing through the cooling channel 6 can flow through the shaft end of the magnetic steel 2 to cool and dissipate heat of the magnetic steel 2.

[0032] The present application sets the sheath of the surface-mounted magnetic steel rotor to include a first sheath and a second sheath, and a cooling channel allowing fluid flow is formed between the first sheath and the second sheath, and the cooling channel can flow through the shaft end of the magnetic steel to cool and dissipate heat of the magnetic steel.

[0033] The rotor air cooling system structure includes a one-way linear cooling air heat exchange path formed between the magnetic steel and the sheath by the force transmission principle, can perform bidirectional heat exchange on the sheath and the magnetic steel, reduces the thermal resistance of the traditional surface-mounted permanent magnet synchronous motor rotor, and improves the air cooling heat exchange efficiency.

[0034] The rotor air cooling system structure does not need to increase additional equipment or redundant rotor structures, and the heat conduction path of the rotor magnetic steel and the sheath is specially optimized, the thermal resistance is reduced, the heat generated by the magnetic steel and the sheath during motor operation is directly sent to the circulating cooling air, and the heat accumulation and uneven heat exchange phenomenon is avoided.

[0035] The sheath of the rotor air cooling system structure is preferably integrally cast, reduces the manufacturing and processing cost, is simple to assemble, and improves the assembly efficiency of the surface-mounted permanent magnet synchronous motor.

[0036] In some embodiments, The rotating shaft 1 includes a magnetic steel assembly section 7 and a first sheath assembly section 8, the first sheath assembly section 8 is connected with the magnetic steel assembly section 7 along the axial direction of the rotating shaft 1, the outer diameter of the magnetic steel assembly section 7 is smaller than that of the first sheath assembly section 8, so as to form a first step surface 9 at the connecting position, along the flow direction of the cooling air flow, the first sheath assembly section 8 is located upstream of the magnetic steel assembly section 7, the magnetic steel 2 is assembled on the outer periphery of the magnetic steel assembly section 7, and the outer periphery of the magnetic steel 2 is arranged to protrude from the outer periphery of the first sheath assembly section 8, so that the air flow can flow to the shaft end surface of the magnetic steel 2 to exchange heat with the magnetic steel 2.

[0037] This is the preferred structure of the shaft of the present application, through the magnetic steel assembly section can be used for setting magnetic steel on its outer periphery, thereby forming a surface-mounted magnetic steel rotor, while the outer diameter of the first sheath assembly section is larger than that of the magnetic steel assembly section, thereby forming an axial first step surface, thereby effectively playing a role in limiting the axial direction of the magnetic steel, and at the same time, the outer periphery of the magnetic steel protrudes the outer periphery of the first sheath assembly section, so that the outer diameter of the magnetic steel is larger than that of the first sheath assembly section, thereby enabling the airflow from the side of the first sheath assembly section to act on the axial end surface of the magnetic steel, thereby improving the cooling effect of the magnetic steel.

[0038] In some embodiments, The shaft 1 further comprises a second sheath assembly section 10, and the outer diameter of the magnetic steel assembly section 7 is also smaller than that of the second sheath assembly section 10, so as to form a second step surface 11 at the joint position therebetween, and the first sheath assembly section 8, the magnetic steel assembly section 7 and the second sheath assembly section 10 are sequentially connected along the axial direction of the shaft 1, and the second sheath assembly section 10 is located downstream of the magnetic steel assembly section 7 along the flow direction of the cooling airflow, and the partial shaft section of the second sheath 5 is located on the outer periphery of the magnetic steel 2, the partial shaft section is located on the outer periphery of the first sheath assembly section 8, and the partial shaft section is located on the outer periphery of the second sheath assembly section 10.

[0039] This is a further preferred structure of the shaft of the present application, through the second sheath assembly section can assemble a sheath on its outer periphery, and the second sheath is located on the other side of the axial direction of the magnetic steel assembly section, so that the magnetic steel assembly section is clamped between the first and second sheath assembly sections, and at the same time, since the outer diameter of the second sheath assembly section is larger than that of the magnetic steel assembly section, thereby forming an axial second step surface, thereby effectively playing a role in limiting the other end of the axial direction of the magnetic steel, and at the same time, the outer periphery of the magnetic steel protrudes the outer periphery of the second sheath assembly section, so that the outer diameter of the magnetic steel is larger than that of the second sheath assembly section, thereby enabling the airflow from the side of the magnetic steel assembly section to act on the axial end surface of the other end of the magnetic steel, thereby further improving the cooling effect of the magnetic steel.

[0040] In some embodiments, The magnetic steel 2 is a plurality of pieces, and the plurality of magnetic steels 2 are sequentially arranged along the circumferential direction of the magnetic steel assembly section 7; and / or, the magnetic steel 2 is a plurality of pieces, and the plurality of magnetic steels 2 are sequentially arranged along the axial direction of the magnetic steel assembly section 7.

[0041] The preferred magnetic steel of the present application is a structure of a plurality of pieces, and the plurality of magnetic steels can be sequentially arranged along the circumferential direction of the magnetic steel assembly section, thereby being able to be spliced into a whole circumferential magnetic steel structure, and also being able to form a plurality of magnetic steel structures sequentially arranged along the axial direction, thereby being able to enhance the axial length of the magnetic steel, and being able to be set into a magnetic steel overall structure of different axial lengths according to needs, thereby improving the general performance of the surface-mounted rotor.

[0042] In some embodiments, The magnetic steel 2 is an arc-shaped ring structure, comprising a magnetic steel outer surface 12 at the outer periphery thereof, a magnetic steel assembly surface 13 at the inner periphery thereof, magnetic steel axial end surfaces 14 at the axial ends thereof, and magnetic steel circumferential end surfaces 15 at the circumferential sides thereof; two or more magnetic steels 2 are spliced in the circumferential direction of the magnetic steel assembly section 7 to form a circular ring structure.

[0043] The present application further provides that the magnetic steel is arranged in an arc-shaped ring structure, the magnetic steel outer surface at the outer periphery thereof is capable of being assembled with the sheath, the magnetic steel assembly surface at the inner periphery thereof is capable of assembling the magnetic steel to the magnetic steel assembly section, the magnetic steel axial end surfaces are capable of receiving the cooling of the airflow, and the magnetic steels spliced in the axial direction form different axial sections, and the magnetic steel circumferential end surfaces are capable of being spliced in the circumferential direction to form a circular ring structure, so as to achieve the effect of generating magnetic action in the circumferential direction.

[0044] In some embodiments, The second sheath 5 comprises a magnetic steel sheath section 16 and a first rotating shaft sheath section 17, at least part of the structure of the magnetic steel sheath section 16 is located at the outer periphery of the magnetic steel 2, the first rotating shaft sheath section 17 is located at the outer periphery of the first sheath assembly section 8, and the magnetic steel sheath section 16 and the first rotating shaft sheath section 17 are both ring structures, the inner diameter of the magnetic steel sheath section 16 is greater than the outer diameter of the first rotating shaft sheath section 17, the outer diameter of the magnetic steel 2 is greater than the outer diameter of the first rotating shaft sheath section 17, the first rotating shaft sheath section 17 and the first sheath 4 are arranged in a spaced manner to form a first cooling channel 18, the cooling channel 6 comprises the first cooling channel 18, and the first cooling channel 18 is opposite to the axial end surface of the magnetic steel 2, so that the fluid flowing in the first cooling channel 18 can reach the axial end surface of the magnetic steel 2 to cool the magnetic steel 2.

[0045] This is the preferred structure of the second sheath of the present application, the magnetic steel sheath section can wrap and fix the magnetic steel at the outer periphery, the first rotating shaft sheath section can wrap and fix the first sheath assembly section, and the inner diameter of the magnetic steel sheath section is greater than the outer diameter of the first rotating shaft sheath section, so that the airflow in the first cooling channel between the first rotating shaft sheath section and the first sheath can flow to the axial end surface of the magnetic steel, achieving the cooling of the axial end surface of the magnetic steel.

[0046] In some embodiments, The magnetic steel sheath segment 16 and the first rotating shaft sheath segment 17 are arranged in the axial direction of the rotating shaft 1 to form a first interval channel 19 allowing gas flow, the magnetic steel sheath segment 16 and the first sheath 4 are arranged in interval to form a second cooling channel 20, the cooling channel 6 comprises the second cooling channel 20, the first cooling channel 18, the first interval channel 19 and the second cooling channel 20 are communicated in sequence, the first cooling channel 18 is located upstream of the second cooling channel 20 in the gas flow direction, and part of the structure of the magnetic steel 2 can extend into the first interval channel 19 so that the axial end face and the circumferential end face of the magnetic steel 2 located in the first interval channel 19 can be cooled by gas.

[0047] The application further arranges the first rotating shaft sheath segment and the magnetic steel sheath segment in interval to form a first interval channel, and part of the structure of the magnetic steel extends into the first interval channel, so that the axial end face and the circumferential end face of the magnetic steel can be further cooled and radiated, the cooling and radiating performance of the magnetic steel is further improved, the radiating efficiency of the rotor structure of the surface-mounted permanent magnet synchronous motor is further improved, and the demagnetization risk of the rotor magnetic steel is reduced.

[0048] In some embodiments, The second sheath 5 further comprises a second rotating shaft sheath segment 21, when the rotating shaft 1 further comprises a second sheath assembly segment 10, the second rotating shaft sheath segment 21 is located at the outer periphery of the second sheath assembly segment 10, and the second rotating shaft sheath segment 21 is in ring structure, the inner diameter of the magnetic steel sheath segment 16 is greater than the outer diameter of the second rotating shaft sheath segment 21, the outer diameter of the magnetic steel 2 is greater than the outer diameter of the second rotating shaft sheath segment 21, the second rotating shaft sheath segment 21 and the first sheath 4 are arranged in interval to form a third cooling channel 22, the cooling channel 6 comprises the third cooling channel 22, the third cooling channel 22 is opposite to the axial end face of the magnetic steel 2, so that the fluid flowing in the second cooling channel 20 can reach the axial end face of the magnetic steel 2 to cool the magnetic steel 2.

[0049] This is a further preferred structure of the second sheath of the application, the second rotating shaft sheath segment can wrap and fix the second sheath assembly segment, the inner diameter of the magnetic steel sheath segment is greater than the outer diameter of the second rotating shaft sheath segment, and the outer diameter of the magnetic steel is greater than the outer diameter of the second rotating shaft sheath segment, so that the incoming gas of the second cooling channel can flow to the axial end face of the magnetic steel to cool and radiate the axial end face of the magnetic steel, and then flow to the third cooling channel between the second rotating shaft sheath segment and the second sheath.

[0050] In some embodiments, The magnetic steel sheath section 16 and the second shaft sheath section 21 are arranged in the axial direction of the shaft 1 to form a second interval channel 23 allowing airflow to pass through, the second cooling channel 20, the second interval channel 23 and the third cooling channel 22 are sequentially communicated, and part of the structure of the magnetic steel 2 can extend into the second interval channel 23, so that the axial end face and the circumferential end face of the magnetic steel 2 located in the second interval channel 23 can be cooled by the gas.

[0051] The present application further arranges the second shaft sheath section and the magnetic steel sheath section to form a second interval channel, and the part of the structure of the magnetic steel extends into the second interval channel, so as to further cool and dissipate heat from the other axial end face and the circumferential end face of the magnetic steel, further improve the cooling and heat dissipation performance of the magnetic steel, and further improve the heat dissipation efficiency of the rotor structure of the surface-mounted permanent magnet synchronous motor and reduce the demagnetization risk of the rotor magnetic steel.

[0052] In some embodiments, The inner periphery of the magnetic steel sheath section 16 is in abutment and interference with the outer periphery of the magnetic steel 2, the first shaft sheath section 17 is in abutment and interference with the outer periphery of the first sheath assembly section 8, and the second shaft sheath section 21 is in abutment and interference with the outer periphery of the second sheath assembly section 10.

[0053] This is the preferred cooperation form of the magnetic steel sheath section and the magnetic steel of the present application, and the magnetic steel is preferably in interference with the magnetic steel sheath section, which can fix the magnetic steel in the radial and circumferential directions to prevent the magnetic steel from falling off during operation. The first shaft sheath section is in interference with the first sheath assembly section, and the second shaft sheath section is in interference with the second sheath assembly section, so that the sheath and the rotor are fixedly assembled as a whole to form an integrated rotation and achieve the fixing effect of the magnetic steel.

[0054] In some embodiments, The first shaft sheath section 17 and the first sheath 4 are further provided with a first support part 24, the first support part 24 has at least two, and the at least two first support parts 24 are arranged in the circumferential direction of the shaft 1 to form the first cooling channel 18 between adjacent first support parts 24. The second shaft sheath section 21 and the first sheath 4 are further provided with a third support part 26, the third support part 26 has at least two, and the at least two third support parts 26 are arranged in the circumferential direction of the shaft 1 to form the third cooling channel 22 between adjacent third support parts 26.

[0055] The application further supports the first shaft sleeve segment and the first sleeve through the first support part arranged between the first shaft sleeve segment and the first sleeve, forms a first cooling channel, and the adjacent first support parts are arranged at intervals to make the first cooling channel unobstructed so that the cooling gas can flow smoothly.

[0056] In some embodiments, The second support part 25 is arranged between the magnetic steel sleeve segment 16 and the first sleeve 4, and the second support part 25 has at least two second support parts 25 arranged at intervals in the circumferential direction of the shaft 1, so that the second cooling channel 20 is formed between the adjacent second support parts 25. The at least two second support parts 25 are also arranged at intervals in the axial direction of the shaft 1.

[0057] The application further supports the first shaft sleeve segment and the first sleeve through the first support part arranged between the first shaft sleeve segment and the first sleeve, forms a first cooling channel, and the adjacent first support parts are arranged at intervals to make the first cooling channel unobstructed so that the cooling gas can flow smoothly.

[0058] The application improves and redesigns the rotor structure of a permanent magnet synchronous high-speed motor with a metal sleeve. On the inner side of the metal sleeve, interference torque transmission bridges (first, second, and third support parts) are designed and added to the corresponding regions of the sleeve and the magnetic steel and the shaft shoulder contact. Interference contact surfaces are added to the ends of the torque transmission bridges. Due to the presence of the interference torque transmission bridges, a new heat exchange path (cooling channel 6) for cooling air is added between the metal sleeve and the magnetic steel. With the support of this path, the cooling air can exchange heat with the magnetic steel and the inner surface of the metal sleeve in both directions, directly transferring the heat generated by the two parts into the externally applied cooling air with a flow rate. This avoids heat accumulation during the process. This rotor structure does not affect the interference assembly between the magnetic steel and the sleeve, thereby ensuring the strength of the rotor in the high-speed rotating state. At the same time, the interference torque transmission bridges can lift the entire sleeve, and the cooling air flow path formed by them is annular and axially connected. The cooling air is more easily matched with the dynamic thermal characteristics of the rotor during high-speed rotation, thereby improving the cooling efficiency.

[0059] In some embodiments, When the rotating shaft 1 further comprises a second sheath assembly section 10, the axial dimension sum of the first sheath assembly section 8, the second sheath assembly section 10 and the magnetic steel assembly section 7 is L along the axial direction of the rotating shaft 1, the axial dimension of the first rotating shaft sheath section 17 is Lb, the axial dimension of the second rotating shaft sheath section 21 is Lb, the axial dimension of the magnetic steel sheath section 16 is La, and L≥La+2Lb.

[0060] The present application can ensure that the lengths of the three sections of the rotating shaft are as long as possible than the lengths of the three sheath sections, thereby increasing the lengths of the first and second interval channels as much as possible, improving the cooling effect on the axial end surface and the circumferential end surface of the magnetic steel, but ensuring the support strength of the magnetic steel and the rotating shaft.

[0061] The present application also provides an electric machine comprising the aforementioned rotor assembly.

[0062] The present application solves the following technical problems: 1. Structural compatibility contradiction: the internal space height of the high-speed motor rotor is limited, and the traditional air cooling system (such as radial air duct or axial fan) is difficult to be embedded in the rotor structure, and the static heat dissipation design cannot match the dynamic thermal characteristics of the high-speed rotating rotor, resulting in low cooling efficiency.

[0063] 2. Lack of magnetic steel heat exchange stability: most of the existing technologies improve the overall heat dissipation capacity by optimizing the fan air volume or the fin design, but do not optimize the heat conduction path of the rotor magnetic steel, resulting in unstable heat exchange interface between the magnetic steel and the cooling medium, and cannot realize continuous and uniform heat exchange, which aggravates the risk of rotor thermal runaway.

[0064] 3. Unable to simultaneously cool the inside and outside of the sheath: the sheath used in the high-speed motor rotor is only air-cooled and heat-exchanged through the air gap between the stator and the rotor, and cannot be heat-exchanged from the inside of the sheath, resulting in very low cooling efficiency of the air cooling system for the rotor.

[0065] The processing process of the high-speed motor cooling system and the components thereof of the present application is as follows: Firstly, the processing of the metal sheath, because the prior art uses the method of line cutting + inner and outer circle grinding to process ordinary metal sheath, but because the sheath contained in the present application is composed of sheath body bearing part (first sheath 4), interference contact surface (sheath-magnetic steel) (magnetic steel sheath section 16), interference contact surface (sheath-shoulder) (first shaft sheath section 17), interference torque transmission bridge (sheath-shoulder) (first support part 24 and third support part 26), interference torque transmission bridge (sheath-magnetic steel) (second support part 25), so the method of integral casting is used to process the sheath, after the processing is completed, the outer surface of the sheath body bearing part (first sheath 4) and the inner surface of the interference contact surface (sheath-magnetic steel) (magnetic steel sheath section 16), interference contact surface (sheath-shoulder) (first shaft sheath section 17) are ground, so as to ensure the stability when contacting with the shaft 1 and the outer surface of the magnetic steel 12.

[0066] After the processing of the metal sheath contained in the rotor cooling system is completed, the magnetic steel and the shaft are assembled. First, a higher stability glue material such as AB epoxy resin glue is used, and is uniformly applied to the magnetic steel and shaft assembly surface (inside) (magnetic steel assembly surface 13), magnetic steel and shaft assembly surface (axial) (magnetic steel shaft end surface 14), and then the two surfaces of the above-mentioned magnetic steel are placed on the shaft and magnetic steel assembly surface (inside) (magnetic steel assembly section 7), shaft and magnetic steel assembly surface (axial) (first step surface 9 and second step surface 11), after all the magnetic steel and shaft 1 are installed, it is necessary to wait for a day for the glue to solidify, and then because the roughness of the outer surface of the magnetic steel needs to be controlled at about 1.6, the magnetic steel outer surface of the shaft with the magnetic steel is ground.

[0067] After completing all the above processes, the metal sheath is heated. The heating temperature and time need to be determined according to the alloy material characteristics of the sheath itself. Utilizing the principle of thermal expansion and contraction, the metal sheath is first enlarged as a whole. Then, the interference contact surface (sheath-magnet) (magnet sheath section 16) is aligned with the outer surface 12 of the magnet, and the interference contact surface (sheath-shoulder) (first shaft sheath section 17) is aligned with the shoulder and the mating surface of the sheath (first sheath mating section 8 and second sheath mating section 10). After the sheath cools down, the metal sheath included in this invention will shrink as a whole and be assembled onto the shaft with the magnet in an interference manner. At this time, the rotor structure included in this invention has been assembled. At this point, the interference torque of the entire rotor structure is mainly generated by the load-bearing part of the sheath (first sheath 4). First, under the action of the interference torque transmission bridge (sheath-magnet) (second support 25), the torque is transmitted to the interference contact surface (sheath-magnet) (magnet sheath section 16). Then, the rotor magnet part is fixed. The interference torque transmission bridge (sheath-magnet) (second support 25) is distributed in 4 axial directions and 4 circumferential directions, for a total of 16 bridges. This number distribution needs to be determined according to the number of segments of the surface-mounted magnet. That is, in order to ensure that the interference torque is not lost during the transmission process, the interference torque transmission bridge (sheath-magnet) is generally... The number of sleeve-magnet (second support 25) must be equal to the number of magnets; for the assembly of the sleeve and the shaft shoulder, the interference torque is transmitted by the interference torque transmission bridge (sleeve-shaft shoulder) (first support 24 and third support 26) to the interference contact surface (sleeve-shaft shoulder) (first shaft sleeve section 17), and then the sleeve and the shaft 1 are fixed to ensure the consistency of the interference torque between the sleeve and the magnet and the shaft contact surface. There are two interference torque transmission bridges (sleeve-shaft shoulder) (first support 24 and third support 26) in the circumferential direction, and they are 180° apart. Since the shaft has two shaft shoulders, the total number is 4. For the axial length La of the interference contact surface (sleeve-magnet) (magnet sleeve section 16) and the axial length Lb of the interference contact surface (sleeve-shoulder) (first shaft sleeve section 17), L ≥ La + 2Lb should be satisfied, where L is the maximum distance between the two shoulders of the shaft. It should be noted that the thickness of the magnet should be greater than the height of the shoulder, thus exposing the magnet to the cooling air while simultaneously allowing it to be fixed to the shaft by the interference contact surface (sleeve-magnet) (magnet sleeve section 16). With this structure, external cooling air can pass through the axial cooling duct supported by the torque transmission bridge, and because the axial surface of the magnet is exposed to the air (as shown in the attached diagram), the external cooling air can reach the shaft. Figure 5 As shown in section 14 of the magnet shaft end face, cooling air can be drawn from inside the sheath to provide uniform and stable heat exchange between the magnet and the sheath, thereby cooling the rotor.

[0068] At this point, all the parts included in this invention have been assembled.

[0069] The above merely describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application. The above merely describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A rotor assembly characterized by: The rotor assembly comprises a rotating shaft (1), a magnetic steel (2) and a sheath (3), the magnetic steel (2) is arranged on the outer periphery of a part of the rotating shaft (1), at least part of the sheath (3) is arranged on the outer periphery of the magnetic steel (2), the sheath (3) comprises a first sheath (4) and a second sheath (5), the first sheath (4) is arranged on the outer periphery of the second sheath (5), and the first sheath (4) and the second sheath (5) are arranged in a spaced manner, so that a cooling channel (6) allowing fluid flow is formed between the first sheath (4) and the second sheath (5), and the airflow flowing through the cooling channel (6) can flow to the shaft end of the magnetic steel (2) to cool the magnetic steel (2).

2. The rotor assembly according to claim 1, wherein: the rotating shaft (1) comprises a magnetic steel assembly section (7) and a first sheath assembly section (8), the first sheath assembly section (8) is connected to the magnetic steel assembly section (7) along the axial direction of the rotating shaft (1), the outer diameter of the magnetic steel assembly section (7) is smaller than the outer diameter of the first sheath assembly section (8), so that a first step surface (9) is formed at the connecting position of the two sections, along the flow direction of the cooling airflow, the first sheath assembly section (8) is located upstream of the magnetic steel assembly section (7), the magnetic steel (2) is arranged on the outer periphery of the magnetic steel assembly section (7), and the outer periphery of the magnetic steel (2) is arranged protruding from the outer periphery of the first sheath assembly section (8), so that the airflow can flow to the shaft end surface of the magnetic steel (2) to exchange heat with the magnetic steel (2).

3. The rotor assembly according to claim 2, wherein: the rotating shaft (1) further comprises a second sheath assembly section (10), the outer diameter of the magnetic steel assembly section (7) is also smaller than the outer diameter of the second sheath assembly section (10), so that a second step surface (11) is formed at the connecting position of the two sections, the first sheath assembly section (8), the magnetic steel assembly section (7) and the second sheath assembly section (10) are connected in sequence along the axial direction of the rotating shaft (1), along the flow direction of the cooling airflow, the second sheath assembly section (10) is located downstream of the magnetic steel assembly section (7), part of the shaft section of the second sheath (5) is located on the outer periphery of the magnetic steel (2), part of the shaft section is located on the outer periphery of the first sheath assembly section (8), and part of the shaft section is located on the outer periphery of the second sheath assembly section (10).

4. The rotor assembly according to claim 2, wherein: the magnetic steel (2) is a plurality of magnetic steels, and the plurality of magnetic steels (2) are arranged in sequence along the circumferential direction of the magnetic steel assembly section (7); and / or the magnetic steel (2) is a plurality of magnetic steels, and the plurality of magnetic steels (2) are arranged in sequence along the axial direction of the magnetic steel assembly section (7).

5. The rotor assembly according to claim 4, wherein: ​ The magnetic steel (2) is an arc-shaped ring structure, comprising a magnetic steel outer surface (12) at the outer periphery thereof, a magnetic steel assembly surface (13) at the inner periphery thereof, magnetic steel shaft end surfaces (14) at the axial ends thereof, and magnetic steel circumferential end surfaces (15) at the circumferential sides thereof; two or more of the magnetic steel (2) are spliced along the circumferential direction of the magnetic steel assembly section (7) to form a circular ring structure.

6. The rotor assembly of claim 2, wherein: The second sheath (5) comprises a magnetic steel sheath section (16) and a first shaft sheath section (17), at least part of the structure of the magnetic steel sheath section (16) is located at the outer periphery of the magnetic steel (2), the first shaft sheath section (17) is located at the outer periphery of the first sheath assembly section (8), and the magnetic steel sheath section (16) and the first shaft sheath section (17) are both ring structures, the inner diameter of the magnetic steel sheath section (16) is greater than the outer diameter of the first shaft sheath section (17), the outer diameter of the magnetic steel (2) is greater than the outer diameter of the first shaft sheath section (17), the first shaft sheath section (17) and the first sheath (4) are spaced apart to form a first cooling channel (18), the cooling channel (6) comprises the first cooling channel (18), the first cooling channel (18) is opposite to the shaft end surface of the magnetic steel (2), so that the fluid flowing in the first cooling channel (18) can reach the shaft end surface of the magnetic steel (2) to cool the magnetic steel (2).

7. The rotor assembly of claim 6, wherein: The magnetic steel sheath section (16) and the first shaft sheath section (17) are spaced apart in the axial direction of the shaft (1) to form a first spacing channel (19) allowing gas flow, the magnetic steel sheath section (16) and the first sheath (4) are spaced apart to form a second cooling channel (20), the cooling channel (6) comprises the second cooling channel (20), the first cooling channel (18), the first spacing channel (19), and the second cooling channel (20) are sequentially connected, the first cooling channel (18) is located upstream of the second cooling channel (20) in the direction of gas flow, and part of the structure of the magnetic steel (2) can extend into the first spacing channel (19), so that the shaft end surface and the circumferential end surface of the magnetic steel (2) located in the first spacing channel (19) can be cooled by gas.

8. The rotor assembly of claim 7, wherein: The second sheath (5) further comprises a second shaft sheath segment (21), when the shaft (1) further comprises a second sheath assembly segment (10), the second shaft sheath segment (21) is located at the outer periphery of the second sheath assembly segment (10), and the second shaft sheath segment (21) is annular structure, the inner diameter of the magnet steel sheath segment (16) is greater than the outer diameter of the second shaft sheath segment (21), the outer diameter of the magnet steel (2) is greater than the outer diameter of the second shaft sheath segment (21), the second shaft sheath segment (21) and the first sheath (4) are spaced apart to form a third cooling channel (22), the cooling channel (6) comprises the third cooling channel (22), the third cooling channel (22) is opposite to the shaft end face of the magnet steel (2), so that the fluid flowing in the second cooling channel (20) can reach the shaft end face of the magnet steel (2) to cool the magnet steel (2).

9. The rotor assembly of claim 8, wherein: The magnet steel sheath segment (16) and the second shaft sheath segment (21) are spaced apart in the axial direction of the shaft (1) to form a second spaced channel (23) allowing airflow to flow through, the second cooling channel (20), the second spaced channel (23) and the third cooling channel (22) are sequentially communicated, and part of the structure of the magnet steel (2) can extend into the second spaced channel (23), so that the shaft end face and the circumferential end face of the magnet steel (2) located in the second spaced channel (23) can be cooled by gas.

10. The rotor assembly of claim 8, wherein: The inner periphery of the magnet steel sheath segment (16) is in contact with and interference fitted to the outer periphery of the magnet steel (2), the first shaft sheath segment (17) is in contact with and interference fitted to the outer periphery of the first sheath assembly segment (8), and the second shaft sheath segment (21) is in contact with and interference fitted to the outer periphery of the second sheath assembly segment (10).

11. The rotor assembly of claim 8, wherein: The first shaft sheath segment (17) and the first sheath (4) are further provided with a first support part (24), the first support part (24) has at least two, and at least two first support parts (24) are spaced apart along the circumferential direction of the shaft (1), so that the first cooling channel (18) is formed between adjacent first support parts (24); The second shaft sheath segment (21) and the first sheath (4) are further provided with a third support part (26), the third support part (26) has at least two, and at least two third support parts (26) are spaced apart along the circumferential direction of the shaft (1), so that the third cooling channel (22) is formed between adjacent third support parts (26).

12. The rotor assembly of claim 7, wherein: The magnetic steel sheath section (16) and the first sheath (4) are further provided with a second support part (25), the second support part (25) has at least two, and the at least two second support parts (25) are arranged in the circumferential direction of the rotating shaft (1) and are spaced apart, so that the second cooling channel (20) is formed between adjacent second support parts (25); The at least two second support parts (25) are also arranged in the axial direction of the rotating shaft (1) and are spaced apart.

13. The rotor assembly according to claim 8, characterized in that: When the rotating shaft (1) further comprises a second sheath assembly section (10), the axial dimensions of the first sheath assembly section (8), the second sheath assembly section (10) and the magnetic steel assembly section (7) are L in the axial direction of the rotating shaft (1), the axial dimension of the first rotating shaft sheath section (17) is Lb, the axial dimension of the second rotating shaft sheath section (21) is Lb, the axial dimension of the magnetic steel sheath section (16) is La, and L≥La+2Lb.

14. An electric machine characterized by: The rotor assembly according to any one of claims 1-13.

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