High-speed motor rotor self-cooling structure

Abstract

The invention discloses a high-speed motor rotor self-cooling structure. The high-speed motor rotor self-cooling structure 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 sleeved with the sheath, the two ends of the sheath are detachably connected with the hollow rotating shaft through end plates, a shaft hole is formed in one end of the hollow rotating shaft to be communicated with outside air, and a first axial air channel, a second axial air channel and a radial ventilation channel are formed in the hollow rotating shaft. The first axial air duct and the second axial air duct are communicated through the radial ventilation duct, and the first axial air duct is communicated with the outside through the shaft hole. According to the self-cooling structure, self-suction air cooling is achieved by means of centrifugal force generated when the rotor rotates at a high speed, and external cooling equipment is not needed. And the axial air duct is arranged, so that the convective heat transfer coefficient of the rotor and air is further improved, and the heat dissipation effect is enhanced. And the hollow rotating shaft is in transition fit, so that the manufacturing and assembling difficulty is reduced.

Description

Technical Field

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

[0002] High-speed permanent magnet motors have characteristics such as high efficiency and high power density, and have received extensive attention in modern industrial applications. Considering the rotor strength, the surface-mounted high-speed permanent magnet motor with an integral iron core and alloy rotating shaft protected by a carbon fiber sleeve has become an application trend. On the other hand, while the motor speed increases, the motor magnetic field frequency increases accordingly, resulting in an increase in harmonic frequency, which increases the rotor eddy current loss (including the permanent magnet eddy current loss and the rotating shaft eddy current loss). After introducing the harmonic current of the controller, this phenomenon is further aggravated.

[0003] The increase in rotor temperature rise caused by rotor eddy current loss increases the risk of demagnetization of permanent magnets. An efficient rotor heat dissipation structure is the key to ensuring the reliable operation of high-speed permanent magnet motors. At present, the commonly used rotor cooling structures for high-speed motors include oil cooling and forced air cooling. The oil cooling structure poses extremely high requirements for the sealing process under high-speed and high-temperature conditions. In the conventional forced air cooling structure, air flows through the air gap to cool the rotor surface, and the cooling effect is very unsatisfactory when using a carbon fiber sleeve with extremely poor thermal conductivity. In addition, both oil cooling and air cooling require supporting external equipment, which increases the complexity of the system.

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

[0005] The present invention provides a self-cooling structure for a high-speed motor rotor, which enables self-suction air cooling by means of the centrifugal force generated during the high-speed rotation of the rotor through the setting of a hollow rotating shaft, without the need for external cooling equipment and having two axially connected air ducts, 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 its technical problems is a self-cooling structure for a high-speed motor rotor, which includes: a hollow rotating shaft, a permanent magnet, and a sheath;

[0007] The permanent magnet is disposed on the outer surface of the hollow rotating shaft, the sheath is sleeved outside the permanent magnet, both ends of the sheath are detachably connected to the hollow rotating shaft through end plates, one end of the hollow rotating shaft is provided with a shaft hole to communicate with the outside air, and a first axial air duct, a second axial air duct, and a radial ventilation duct are provided inside 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 shaft hole.

[0008] Preferably, the hollow rotating shaft comprises 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 inclined radial air ducts in the radial direction, the inner rotating shaft layer is provided with the first axial air duct in the axial direction, and the first axial air duct is communicated with the second axial air duct through the radial air ducts.

[0009] Preferably, a plurality of inner rotating shaft teeth are arranged on the outer wall of the inner rotating shaft layer, a plurality of outer rotating shaft grooves are arranged on the inner wall of the outer rotating shaft layer corresponding to the inner rotating shaft teeth, the inner rotating shaft teeth and the outer rotating shaft grooves are in one-to-one transition fit, and the second axial air duct is located between adjacent outer rotating shaft grooves.

[0010] Preferably, the radial air ducts are arranged close to the shaft hole and a plurality of the radial air ducts are uniformly arranged in a circumferential direction of the inner rotating shaft layer.

[0011] Preferably, the radial air ducts are inclined to the inner rotating shaft layer and the included angle between the radial air ducts and the axial cross-section of the inner rotating shaft layer is not less than 100 degrees.

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

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

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

[0015] For a self-cooling structure of a high-speed motor rotor of the present invention, through the arrangement of the radial air ducts, when the rotor rotates at a high speed, the rotor does work on the air in the radial air ducts, so that the total pressure of the air increases, 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 flow path of shaft hole - first axial air duct - radial air duct - second axial air duct, so that the self-cooling structure of the high-speed motor rotor can cool and dissipate heat from the high-speed motor rotor without external cooling equipment and cold sources, avoiding the introduction of external auxiliary fan equipment and reducing the complexity of the system.

[0016] Moreover, the first axial air duct and the second axial air duct are arranged such that when the rotor is operating, air convection can be rapidly formed inside the hollow rotating shaft and the permanent magnets through the first axial air duct and the second axial air duct, enhancing the heat dissipation efficiency of the rotor. In addition, the hollow rotating shaft adopts a double-layer rotating shaft structure, and torque is transmitted through tooth-groove cooperation, reducing the processing and assembly difficulty. Description of the Drawings

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

[0018] Figure 2 is the sectional structural schematic diagram of the self-cooling structure of the high-speed motor rotor of the present invention;

[0019] Figure 3 is the structural schematic 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 is the structural schematic 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 is the end-face structural schematic diagram of the assembled double-layer rotating shaft of the self-cooling structure of the high-speed motor rotor of the present invention;

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

[0023] Description of the Reference Numerals: 1, hollow rotating shaft; 101, outer layer of the rotating shaft; 102, groove on the outer layer of the rotating shaft; 103, second axial air duct; 104, inner layer of the rotating shaft; 105, radial ventilation duct; 106, shaft hole; 107, teeth on the inner layer of the rotating shaft; 108, air flow direction; 109, first axial air duct;

[0024] 201, left end plate; 202, right end plate; 203, ventilation holes on the end plate; 3, sheath; 4, permanent magnet. Detailed Embodiments

[0025] The present invention will be further described below in conjunction with the drawings and embodiments.

[0026] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0027] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes 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 commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

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

[0030] In this embodiment, a shaft hole 106 is provided at one end of the self-cooling structure of the high-speed motor rotor. When the rotor rotates at a high speed, the rotor does work on the air in the radial ventilation duct 105, increasing the total pressure of the air, sucking the outside air from the shaft hole 106 into the first axial air duct 109, and pushing it into the second axial air duct 103, forming an air flow path of shaft hole 106 - first axial air duct 109 - radial ventilation duct 105 - second axial air duct 103, so that the self-cooling structure of the high-speed motor rotor can cool and dissipate heat from the high-speed motor rotor without external cooling equipment and cold sources, avoiding the introduction of external auxiliary fan equipment and reducing the complexity of the system. Moreover, through the arrangement of the first axial air duct 109 and the second axial air duct 103, the self-cooling structure of the high-speed motor rotor can quickly form air convection inside the hollow rotating shaft 1 and the permanent magnet 4 through the first axial air duct 109 and the second axial air duct 103 during operation, enhancing the heat dissipation efficiency of the rotor. The sheath 3 is preferably a carbon fiber sheath 3.

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

[0032] In this embodiment, the radial air ducts 105 adopt an inclined structure. The air in the radial air ducts 105 generates a radial velocity and an axial velocity under the action of centrifugal force. Its 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 and right ends of the second axial air duct 103. In a preferred embodiment, the inclination angle of the radial air ducts 105 determines the axial flow velocity of the air when it enters 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 ducts 105 with respect to the horizontal direction is 120°, which can enable the self-cooling structure of the high-speed motor rotor to achieve a better cooling effect. Moreover, the second axial air duct 103 is 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 rotating shaft; in addition, the setting of the second axial air duct 103 further increases the contact area between the air and the rotor, improves the convective heat transfer ability between the air and the rotor, and enhances the cooling effect.

[0033] As Figures 3 - 5 shown, a plurality of inner rotating shaft teeth 107 are provided on the outer wall of the inner rotating shaft layer 104, and a plurality of outer rotating shaft grooves 102 corresponding to the inner rotating shaft teeth 107 are provided on the inner wall of the outer rotating shaft layer 101. The inner rotating shaft teeth 107 and the outer rotating shaft grooves 102 are in one-to-one transition fit, and the second axial air duct 103 is located between adjacent outer rotating shaft grooves 102. The radial air ducts 105 are arranged close to the shaft hole 106 and a plurality of radial air ducts 105 are uniformly arranged around the inner rotating shaft layer 104 in the circumferential direction.

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

[0035] And, as Figure 5 shown, the outer layer 101 of the rotating shaft and the inner layer 104 of the rotating shaft are in transitional fit. The outer layer 101 of the rotating shaft is provided with an outer layer groove 102 of the rotating shaft, corresponding to the inner layer teeth 107 on the inner layer 104 of the rotating shaft, for torque transmission. The outer layer 101 of the rotating shaft and the inner layer 104 of the rotating shaft can be processed separately and assembled axially, reducing the processing and assembly difficulty. In order to avoid stress concentration during high-speed rotation, rounded corners are provided at the contact parts between the inner layer teeth 107 of the rotating shaft and the outer layer groove 102 of the rotating shaft.

[0036] See Figure 6 , the end cover includes a left end cover and a right end cover. Both the left end cover and the right end cover are detachably connected to the hollow rotating shaft 1. Both the left end cover and the right end cover are provided with end plate ventilation holes 203 corresponding to the second axial duct 103. One end of the hollow rotating shaft 1 is provided with a shaft hole 106, and the other end of the hollow rotating shaft 1 is sealed and a boss is provided at the sealed end of the hollow rotating shaft 1 for the convenience of connection of the hollow rotating shaft 1.

[0037] In this embodiment, the axials of the outer layer 101 of the rotating shaft and the inner layer 104 of the rotating shaft are limited by the left end plate 201 and the right end plate 202 to prevent the hollow rotating shaft 1 from moving axially during use. Among them, the left end plate 201 and the right end plate 202 have the same structure. In order to ensure that the second axial duct 103 is not blocked, end plate ventilation holes 203 are provided on both end plates, and their axial cross-sections are the same as the axial cross-section of the second axial duct 103. In this embodiment, the air flowing out of the end plate ventilation opening is discharged from the motor. In other applications, it can also be used to cool the end of the stator winding.

[0038] In a preferred embodiment, the hollow rotating shaft 1 is forged from alloy steel. When rotating at high speed, under the action of the harmonic magnetic field, great eddy current losses will occur in both the hollow rotating shaft 1 and the permanent magnet 4. Through this high-speed motor rotor self-cooling structure, relying on the centrifugal force generated during the high-speed rotation of the rotor, self-ventilation cooling of the rotor is achieved, avoiding the introduction of additional cooling equipment and reducing the complexity of the system. In addition, due to the extremely high rotational speed of the high-speed motor, the air intake volume generated is extremely large, with extremely high cooling efficiency. Moreover, the rotor ventilation duct is close to the heat source, reducing the heat dissipation thermal resistance of the rotor and improving the cooling effect. Further, in order to reduce the machining difficulty of the rotating shaft, a layered structure is adopted, and a tooth-slot structure is used to transmit torque, making machining and assembly easier to carry out.

[0039] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0040] The above embodiments only represent several implementation manners of the present invention, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A self-cooling structure for a high-speed motor rotor, the self-cooling structure for the high-speed motor rotor can utilize the centrifugal force generated by the high-speed rotation of the rotor to achieve self-aspirated ventilation cooling, and is characterized in that, The self-cooling structure of the high-speed motor rotor includes: a hollow rotating shaft, a permanent magnet, and a sheath; The permanent magnet is arranged on the outer surface of the hollow rotating shaft, the sheath is sleeved outside the permanent magnet, both ends of the sheath are detachably connected to the hollow rotating shaft through end plates, one end of the hollow rotating shaft is provided with a shaft hole to communicate with the outside air, a first axial air duct, a second axial air duct and a radial ventilation duct are arranged in the hollow rotating shaft, the first axial air duct and the second axial air duct are communicated through the radial ventilation duct, and the first axial air duct is communicated with the outside through the shaft hole.

2. The self-cooling structure of the high-speed motor rotor according to claim 1, characterized in that, 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 second axial air duct is arranged in the outer rotating shaft layer, the inclined radial ventilation duct is arranged in the inner rotating shaft layer in the radial direction, the first axial air duct is arranged in the inner rotating shaft layer in the axial direction, and the first axial air duct and the second axial air duct are communicated through the radial ventilation duct.

3. The self-cooling structure of the high-speed motor rotor according to claim 2, characterized in that, A plurality of inner rotating shaft teeth are arranged on the outer wall of the inner rotating shaft layer, a plurality of outer rotating shaft grooves are correspondingly arranged on the inner wall of the outer rotating shaft layer for the inner rotating shaft teeth, the inner rotating shaft teeth and the outer rotating shaft grooves are in one-to-one corresponding transition fit, and the second axial air duct is located between adjacent outer rotating shaft grooves.

4. The self-cooling structure of the high-speed motor rotor according to claim 2, wherein, The radial ventilation duct is arranged close to the shaft hole and a plurality of the radial ventilation ducts are evenly arranged in a circumferential direction of the inner rotating shaft layer.

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

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

7. The self-cooling structure of the high-speed motor rotor 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 a boss is arranged at the sealed end of the hollow rotating shaft to facilitate the connection of the hollow rotating shaft.

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