High-speed motor rotor self-cooling structure

Abstract

A high-speed motor rotor self-cooling structure, which comprises a hollow rotating shaft, a permanent magnet and a sheath; the permanent magnet is arranged on the outer surface of the hollow rotating shaft, and the sheath is sleeved outside the permanent magnet; the two ends of the sheath are detachably connected with the hollow rotating shaft through end plates; an axle hole is formed in one end of the hollow rotating shaft to communicate with the outside air; a first axial air duct and a second axial air duct and a radial air duct are formed in the hollow rotating shaft; the first axial air duct and the second axial air duct are communicated through the radial air duct; and the first axial air duct is communicated with the outside air through the axle hole. The self-cooling structure realizes self-suction air cooling by centrifugal force generated when the rotor rotates at high speed, and does not need external cooling equipment. The setting of the axial air duct further improves the convective heat transfer coefficient of the rotor and air, and enhances the heat dissipation effect. The hollow rotating shaft is adopted by transition fit, which reduces the manufacturing and assembly difficulty.

Description

Technical Field

[0001] The present invention relates to the technical field of motor equipment cooling, and more particularly to a high-speed motor rotor self-cooling structure. Background Art

[0002] High-speed permanent magnet motors, with their high efficiency and power density, have attracted widespread attention in modern industrial applications. Considering rotor strength, surface-mount high-speed permanent magnet motors, featuring an integrated core and alloy shaft protected by a carbon fiber sheath, are becoming a popular choice. On the other hand, as motor speeds increase, the frequency of the motor's magnetic field also increases, leading to higher harmonic frequencies and increased rotor eddy current losses (including those in the permanent magnets and the shaft). This phenomenon is exacerbated by the introduction of harmonic currents in the controller.

[0003] The rotor temperature rise caused by rotor eddy current losses increases the risk of permanent magnet demagnetization. An efficient rotor heat dissipation structure is key to ensuring the reliable operation of high-speed permanent magnet motors. Currently, common rotor cooling structures for high-speed motors include oil cooling and forced air cooling. Oil cooling places extremely high demands on the sealing process under high-speed and high-temperature conditions. Conventional forced air cooling, in which air flows through the air gap to cool the rotor surface, is far from ideal when using a carbon fiber sheath with extremely poor thermal conductivity. Furthermore, both oil and air cooling require supporting external equipment, increasing system complexity.

[0004] Therefore, there is an urgent need for an efficient rotor heat dissipation structure that can ensure effective heat dissipation of the rotor while reducing the need for sealing and the complexity of the equipment. Summary of the Invention

[0005] The present invention provides a high-speed motor rotor self-cooling structure, which, through the arrangement of a hollow rotating shaft, can achieve self-priming air cooling by relying on the centrifugal force generated when the rotor rotates at high speed. It does not require external cooling equipment and has two axial air ducts that are interconnected, thereby improving the convective heat transfer effect and ensuring effective heat dissipation of the rotor.

[0006] The technical solution adopted by the present invention to solve the technical problem is a high-speed motor rotor self-cooling structure, wherein the high-speed motor rotor self-cooling structure comprises: a hollow shaft, a permanent magnet and a sheath;

[0007] The permanent magnet is arranged on the outer surface of the hollow rotating shaft, the sleeve is arranged outside the permanent magnet, both ends of the sleeve are detachably connected to the hollow rotating shaft through end plates, an axial hole is provided at one end of the hollow rotating shaft to connect with the outside air, a first axial air duct, a second axial air duct and a radial ventilation duct are provided in the hollow rotating shaft, the first axial air duct and the second axial air duct are connected through the radial ventilation duct, and the first axial air duct is connected to the outside through the axial hole.

[0008] Preferably, the hollow rotating shaft includes an outer rotating shaft layer and an inner rotating shaft layer; the outer rotating shaft layer and the inner rotating shaft layer are connected, the outer rotating shaft layer is provided with the second axial air duct, the inner rotating shaft layer is provided with an inclined radial ventilation duct along the radial direction, the inner rotating shaft layer is provided with the first axial air duct along the axial direction, and the first axial air duct and the second axial air duct are connected through the radial ventilation duct.

[0009] Preferably, a plurality of inner-layer teeth are provided on the outer wall of the inner layer of the shaft, and a plurality of outer-layer grooves are provided on the inner wall of the outer layer of the shaft corresponding to the inner-layer teeth of the shaft, and the inner-layer teeth of the shaft and the outer-layer grooves of the shaft are transitionally matched one by one, and the second axial air duct is located between adjacent outer-layer grooves of the shaft.

[0010] Preferably, the radial ventilation passage is arranged close to the shaft hole and a plurality of the radial ventilation passages are evenly arranged around the circumferential direction of the inner layer of the rotating shaft.

[0011] Preferably, the radial ventilation channel is arranged obliquely to the inner layer of the rotating shaft, and the angle between the radial ventilation channel and the axial cross-section of the inner layer of the rotating shaft is not less than 100 degrees.

[0012] Preferably, the end plate includes a left end plate and a right end plate, and the left end plate and the right end plate are both detachably connected to the hollow rotating shaft. The left end plate and the right end plate are both provided with end plate ventilation holes corresponding to the second axial air duct.

[0013] Preferably, the shaft hole is opened at one end of the hollow shaft, the other end of the hollow shaft is sealed, and a boss is provided at one sealed end of the hollow shaft to facilitate the connection of the hollow shaft.

[0014] The beneficial effects of the present invention are:

[0015] A high-speed motor rotor self-cooling structure of the present invention is provided with a radial ventilation duct. When the rotor rotates at high speed, the rotor does work on the air in the radial ventilation duct, so that the total air pressure increases, and the outside air is sucked into the first axial air duct from the shaft hole and pushed into the second axial air duct, forming an air circulation path of the shaft hole-first axial air duct-radial ventilation duct-second axial air duct. The high-speed motor rotor self-cooling structure does not require external cooling equipment and cold source to cool and dissipate heat for the high-speed motor rotor, avoids the introduction of external auxiliary fan equipment, and reduces the complexity of the system.

[0016] Furthermore, the arrangement of the first and second axial air ducts enables rapid air convection within the hollow shaft and around the permanent magnets during operation, enhancing the rotor's heat dissipation efficiency. Furthermore, the hollow shaft utilizes a double-layer structure with inner and outer layers, transmitting torque through tooth-slot engagement, reducing machining and assembly complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the overall structure of the high-speed motor rotor self-cooling structure of the present invention;

[0018] Figure 2 This is a schematic cross-sectional view of the self-cooling structure of the high-speed motor rotor of the present invention;

[0019] Figure 3 This is a schematic structural diagram of the outer layer of the rotating shaft of the self-cooling structure of the high-speed motor rotor of the present invention;

[0020] Figure 4 This is a schematic structural diagram of the inner layer of the rotating shaft of the self-cooling structure of the high-speed motor rotor of the present invention;

[0021] Figure 5 This is a schematic diagram of the end face structure of the double-layer rotating shaft of the high-speed motor rotor self-cooling structure of the present invention after assembly;

[0022] Figure 6 It is a structural schematic diagram of the end plate of the high-speed motor rotor self-cooling structure of the present invention.

[0023] Explanation of reference numerals: 1, hollow shaft; 101, outer shaft layer; 102, outer shaft groove; 103, second axial air duct; 104, inner shaft layer; 105, radial ventilation duct; 106, shaft hole; 107, inner shaft tooth; 108, air flow direction; 109, first axial air duct;

[0024] 201. Left end plate; 202. Right end plate; 203. End plate ventilation hole; 3. Sheath; 4. Permanent magnet. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] The following description sets forth numerous specific details to facilitate a thorough understanding of the present invention by those skilled in the art. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] In describing the embodiments of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0029] like Figure 1 and Figure 2 As shown, a high-speed motor rotor self-cooling structure can utilize the centrifugal force generated by the high-speed rotation of the rotor to achieve self-priming ventilation cooling. The high-speed motor rotor self-cooling structure includes: a hollow shaft 1, a permanent magnet 4 and a sleeve 3; the permanent magnet 4 is arranged on the outer surface of the hollow shaft 1, and the sleeve 3 is sleeved on the outside of the permanent magnet 4. Both ends of the sleeve 3 are detachably connected to the hollow shaft 1 through end plates. An axial hole 106 is provided at one end of the hollow shaft 1 to connect with the outside air. A first axial air duct 109, a second axial air duct 103 and a radial ventilation duct 105 are provided in the hollow shaft 1. The first axial air duct 109 and the second axial air duct 103 are connected through the radial ventilation duct 105, and the first axial air duct 109 is connected to the outside through the axial hole 106.

[0030] In this embodiment, an axial hole 106 is provided at one end of the high-speed motor rotor self-cooling structure. When the rotor rotates at high speed, the rotor performs work on the air in the radial ventilation duct 105, increasing the total air pressure. External air is drawn from the axial hole 106 into the first axial air duct 109 and pushed into the second axial air duct 103, forming an air circulation path of the axial hole 106 - the first axial air duct 109 - the radial ventilation duct 105 - the second axial air duct 103. This allows the high-speed motor rotor self-cooling structure to cool and dissipate heat for the high-speed motor rotor without the need for external cooling equipment and a cold source, avoiding the introduction of external auxiliary fan equipment and reducing the complexity of the system. Furthermore, the high-speed motor rotor self-cooling structure, through the provision of the first axial air duct 109 and the second axial air duct 103, enables the rotor to simultaneously form air convection inside the hollow shaft 1 and the permanent magnet 4 through the first axial air duct 109 and the second axial air duct 103 during operation, thereby enhancing the heat dissipation efficiency of the rotor. The sheath 3 is preferably a carbon fiber sheath 3.

[0031] Referring to Figure 2 , the hollow shaft 1 comprises a shaft outer layer 101 and a shaft inner layer 104; the shaft outer layer 101 and the shaft inner layer 104 are connected, the shaft outer layer 101 is provided with a second axial air duct 103, the shaft inner layer 104 is provided with an inclined radial air duct 105 along the radial direction, the shaft inner layer 104 is provided with a first axial air duct 109 along the axial direction, and the first axial air duct 109 is communicated with the second axial air duct 103 through the radial air duct 105. The radial air duct 105 is inclined to the shaft inner layer 104, and the included angle between the radial air duct 105 and the axial section of the shaft inner layer 104 is not less than 100 degrees.

[0032] In this embodiment, the radial air duct 105 adopts an inclined structure, and the air in the radial air duct 105 generates radial velocity and axial velocity under the action of centrifugal force. The inclination angle determines the axial flow velocity of the air flowing into the second axial air duct 103 and the air ratio flowing out of the left end and the right end of the second axial air duct 103. In a preferred embodiment, the inclination angle of the radial air duct 105 determines the axial flow velocity of the air entering the second axial air duct 103 and the air ratio flowing out of the end plate. In this embodiment, the inclination angle of the radial air duct 105 with the horizontal direction is 120°, which can make the high-speed motor rotor self-cooling structure achieve better cooling effect. Moreover, the second axial air duct 103 is located inside the rotor and closer to the heat source. The heat generated by the permanent magnet 4 is taken away by the air in the second axial air duct 103 through the shaft. In addition, the arrangement of the second axial air duct 103 further increases the contact area of the air and the rotor, improves the convective heat transfer capacity between the air and the rotor, and enhances the cooling effect.

[0033] As shown in Figure 3-Figure 5 , the outer wall of the shaft inner layer 104 is provided with a plurality of shaft inner layer teeth 107, and the inner wall of the shaft outer layer 101 is provided with a plurality of shaft outer layer grooves 102 corresponding to the shaft inner layer teeth 107. The shaft inner layer teeth 107 and the shaft outer layer grooves 102 are one-to-one transitionally matched, and the second axial air duct 103 is located between adjacent shaft outer layer grooves 102. The radial air duct 105 is provided close to the shaft hole 106 and is uniformly circumferentially arranged along the circumferential direction of the shaft inner layer 104.

[0034] In this embodiment, the radial air duct 105 is arranged close to the air inlet position of the shaft hole 106, so that the air flows through a long enough path in the axial air duct, and the rotor is cooled more fully. In a preferred embodiment, as shown in Figure 3As shown, it has inclined radial ventilation ducts 105, 8 of which are evenly distributed along the circumference and 4 of which are evenly distributed along the axial direction. The radial ventilation ducts 105 are closer to the air inlet side shaft hole 106. The purpose is to make the air flow path in the axial duct longer and improve the cooling effect. When the rotor rotates at high speed, it does work on the air in the radial ventilation duct 105. Under the action of centrifugal force, the outside air flows through the shaft hole 106, passes through the first axial duct 109, is sucked into the radial ventilation duct 105, and is pushed into the second axial duct 103. Figure 2 As shown, the air flow direction 108 shows the air flow path under this self-cooling structure.

[0035] And, as Figure 5 As shown, the outer shaft layer 101 and the inner shaft layer 104 are seamlessly connected. The outer shaft layer 101 is provided with outer shaft grooves 102, which correspond to inner shaft teeth 107 on the inner shaft layer 104 to transmit torque. The outer shaft layer 101 and the inner shaft layer 104 can be machined separately and assembled axially, reducing machining and assembly complexity. To prevent stress concentration during high-speed rotation, the contact areas between the inner shaft teeth 107 and the outer shaft grooves 102 are rounded.

[0036] See also Figure 6 The end plates include a left end plate 201 and a right end plate 202, both of which are detachably connected to the hollow shaft 1. Each of the left end plate 201 and the right end plate 202 has end plate ventilation holes 203 corresponding to the second axial air duct 103. An axial hole 106 is defined at one end of the hollow shaft 1. The other end of the hollow shaft 1 is sealed, and a boss is provided on the sealed end of the hollow shaft 1 to facilitate connection of the hollow shaft 1.

[0037] In this embodiment, the outer shaft layer 101 and the inner shaft layer 104 are axially limited by the left and right end plates 201 and 202 to prevent movement of the hollow shaft 1 during use. The left and right end plates 201 and 202 have identical structures. To prevent blockage of the second axial air duct 103, each end plate is provided with end plate vents 203, whose axial cross-section is identical to that of the second axial air duct 103. In this embodiment, air flowing out of the end plate vents is exhausted from the motor; in other applications, it can also be used to cool the stator winding ends.

[0038] In a preferred embodiment, the hollow shaft 1 is forged by alloy steel, under the action of harmonic magnetic field, great eddy current loss is generated in the hollow shaft 1 and the permanent magnet 4, through the self-cooling structure of the high-speed motor rotor, the self-suction cooling of the rotor is realized by the centrifugal force generated by the high-speed rotation of the rotor, the additional cooling equipment is avoided, the complexity of the system is reduced. In addition, due to the high speed of the high-speed motor, the suction amount generated is great, and the cooling efficiency is high. Moreover, the rotor ventilation channel is close to the heat source, the heat dissipation resistance of the rotor is reduced, and the cooling effect is improved. Further, in order to reduce the processing difficulty of the shaft, a layered structure is used, and a gear slot structure is used to transmit torque, and the processing and assembly are easier to perform.

[0039] The technical features of the above embodiments can be combined in any manner. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope of the present disclosure.

[0040] The above embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A high-speed motor rotor self-cooling structure, which can use the centrifugal force generated by the high-speed rotation of the rotor to achieve self-priming ventilation cooling, characterized in that: The high-speed motor rotor self-cooling structure comprises: a hollow shaft, a permanent magnet and a sheath; The permanent magnet is arranged on the outer surface of the hollow rotating shaft, the sleeve is arranged outside the permanent magnet, and both ends of the sleeve are detachably connected to the hollow rotating shaft through end plates. An axial hole is opened at one end of the hollow rotating shaft to connect with the outside air. A first axial air duct, a second axial air duct and a radial ventilation duct are opened in the hollow rotating shaft. The first axial air duct and the second axial air duct are connected through the radial ventilation duct, and the first axial air duct is connected to the outside through the axial hole; The hollow shaft includes an outer shaft layer and an inner shaft layer; the outer shaft layer and the inner shaft layer are connected, the outer shaft layer is provided with the second axial air duct, the inner shaft layer is provided with the inclined radial ventilation duct along the radial direction, the inner shaft layer is provided with the first axial air duct along the axial direction, and the first axial air duct and the second axial air duct are connected through the radial ventilation duct; The radial ventilation passage is arranged close to the shaft hole and a plurality of the radial ventilation passages are evenly arranged along the circumferential direction of the inner layer of the rotating shaft.

2. The high-speed motor rotor self-cooling structure according to claim 1, characterized in that: A plurality of inner-layer teeth are provided on the outer wall of the inner layer of the shaft, and a plurality of outer-layer grooves are provided on the inner wall of the outer layer of the shaft corresponding to the inner-layer teeth of the shaft. The inner-layer teeth of the shaft and the outer-layer grooves of the shaft are transitionally matched one by one, and the second axial air duct is located between adjacent outer-layer grooves of the shaft.

3. The high-speed motor rotor self-cooling structure according to claim 2, characterized in that: The radial ventilation channel is arranged obliquely to the inner layer of the rotating shaft, and the angle between the radial ventilation channel and the axial cross section of the inner layer of the rotating shaft is not less than 100 degrees.

4. The high-speed motor rotor self-cooling structure according to claim 1, characterized in that: The end plate includes a left end plate and a right end plate, and the left end plate and the right end plate are both detachably connected to the hollow rotating shaft. The left end plate and the right end plate are both provided with end plate ventilation holes corresponding to the second axial air duct.

5. The high-speed motor rotor self-cooling structure according to claim 1, characterized in that: One end of the hollow rotating shaft is provided with the shaft hole, the other end of the hollow rotating shaft is sealed, and one end of the hollow rotating shaft seal is provided with a boss to facilitate the connection of the hollow rotating shaft.

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