Special-shaped heat pipe for improving heat dissipation of permanent magnet rotor and permanent magnet motor

Abstract

The utility model relates to the technical field of motor cooling, and provides a special-shaped heat pipe for improving heat dissipation of a permanent magnet rotor and a permanent magnet motor. The section of the peripheral wall of the special-shaped heat pipe comprises a first arc line segment, a second arc line segment, a third arc line segment and a fourth arc line segment which are sequentially connected end to end, the circle center of the first arc line segment and the circle center of the third arc line segment are located on the same straight line, and the radius of the first arc line segment is smaller than that of the third arc line segment. The two ends of the second arc line segment are tangent to the first end of the first arc line segment and the first end of the third arc line segment respectively, the two ends of the fourth arc line segment are tangent to the second end of the first arc line segment and the second end of the third arc line segment respectively, and the circle centers of the first arc line segment and the third arc line segment are located on the inner side of the special-shaped heat pipe. The circle centers of the second arc line segment and the fourth arc line segment are located on the outer side of the special-shaped heat pipe, the contact area between the special-shaped heat pipe and a heat source is increased, the cooling effect is improved, and the heat exchange efficiency is effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of motor cooling, in particular to a special-shaped heat pipe and a permanent magnet motor for improving the heat dissipation of a permanent magnet rotor. Background Technique

[0002] With the development, popularization and maturity of new energy vehicles, people pursue higher power density and stronger overload capacity of permanent magnet motors, which pose new challenges to the heat dissipation capacity and overload heat dissipation capacity of permanent magnet motors. At present, high-power density permanent magnet motors mainly adopt end oil cooling by circulating liquid channels in the stator housing and passing oil through the axis of the rotor core. Since the rotor core is welded into one body after the production of the permanent magnet motor, the heat dissipation capacity of the middle section of the rotor core is weaker than that of the end during the operation of the motor, which leads to uneven heat distribution and poor heat dissipation in the rotor core. In severe cases, local thermal expansion of the rotor core may occur, resulting in the loss of dynamic balance and high-temperature demagnetization of the permanent magnet.

[0003] A heat pipe is a rapid heat transfer structure based on phase change and convection. The refrigerant in the pipe evaporates and undergoes a phase change when heated in the evaporation section, and takes away heat, which is the latent heat of vaporization of the working liquid. The vapor flows from the central channel to the condensation section of the heat pipe, condenses into a liquid, and releases the latent heat at the same time. Under the action of capillary force or other forces, the liquid flows back to the evaporation section to complete a heat transfer cycle. The heat conduction capacity of the heat pipe exceeds that of any known metal at present. The adaptability design of the existing shape and structure of the heat pipe to the rotor core, as well as the heat dissipation technology combined with the rotor core of the permanent magnet motor, still needs to be improved.

[0004] Specifically, the cross-sectional shape of the existing heat pipe is usually circular, and its contact area with the heat source is small, resulting in poor cooling effect. Content of the Utility Model

[0005] The purpose of the utility model is to provide a special-shaped heat pipe and a permanent magnet motor for improving the heat dissipation of a permanent magnet rotor, so as to solve the problem that the contact area between the heat pipe in the prior art and the heat source is small, resulting in poor cooling effect.

[0006] To achieve the above object, according to the first aspect of the present utility model, a special-shaped heat pipe for improving the heat dissipation of a permanent magnet rotor is provided. The cross-section of the outer peripheral wall of the special-shaped heat pipe includes a first arc segment, a second arc segment, a third arc segment, and a fourth arc segment that are sequentially connected end to end. The centers of the first arc segment and the third arc segment are on a straight line. The radius of the first arc segment is smaller than the radius of the third arc segment. The two ends of the second arc segment are respectively tangent to the first end of the first arc segment and the first end of the third arc segment. The two ends of the fourth arc segment are respectively tangent to the second end of the first arc segment and the second end of the third arc segment. The centers of the first arc segment and the third arc segment are located inside the special-shaped heat pipe, and the centers of the second arc segment and the fourth arc segment are located outside the special-shaped heat pipe. A plurality of spaced-apart protruding tooth rib structures are provided on the inner peripheral wall of the special-shaped heat pipe, and a tooth groove is formed between adjacent two tooth rib structures. Along the length direction of the special-shaped heat pipe, the special-shaped heat pipe includes a connected first pipe section and a second pipe section, and the first pipe section and the second pipe section are arranged at an angle to each other.

[0007] Further, the straight line where the centers of the first arc segment and the third arc segment are located forms a reference line, and the second arc segment and the fourth arc segment are symmetrically arranged with respect to the reference line; the plane where the junction of the first pipe section and the second pipe section is located forms an interface plane, and the first pipe section and the second pipe section are symmetrically arranged with respect to the interface plane.

[0008] Further, the quadrant point of the third arc segment located on the reference line forms a reference point; the outer peripheral wall of the first pipe section includes a first straight line segment passing through the reference point; the outer peripheral wall of the second pipe section includes a second straight line segment passing through the reference point; the first straight line segment intersects with the second straight line segment, and the included angle between the first straight line segment and the second straight line segment is θ, and the value range of θ is greater than or equal to 175 degrees and less than 180 degrees.

[0009] Further, along the length direction of the special-shaped heat pipe, a plurality of spaced-apart tooth rib structures on the inner peripheral wall of the first pipe section and a plurality of spaced-apart tooth rib structures on the inner peripheral wall of the second pipe section both extend to the interface plane; the plurality of tooth rib structures on the inner peripheral wall of the first pipe section and the plurality of tooth rib structures on the inner peripheral wall of the second pipe section are symmetrically arranged with respect to the interface plane.

[0010] Further, the special-shaped heat pipe includes a first ring-shaped enclosure, a second ring-shaped enclosure, a first end plate, a second end plate, and a partition; the second end of the first ring-shaped enclosure is connected to the first end of the second ring-shaped enclosure, the first end plate is connected to the first end of the first ring-shaped enclosure, the second end plate is connected to the second end of the second ring-shaped enclosure, and the partition is arranged at the junction of the first ring-shaped enclosure and the second ring-shaped enclosure; the first pipe section formed by the first ring-shaped enclosure, the first end plate, and the partition, and the second pipe section formed by the second ring-shaped enclosure, the second end plate, and the partition. A first closed space for filling a refrigerant is provided in the first pipe section, and a second closed space for filling a refrigerant is provided in the second pipe section.

[0011] Further, the radius of the first arc segment is R; the radius of the third arc segment is 2R; the radii of the second arc segment and the fourth arc segment are both 2R; the distance between the centers of the first arc segment and the third arc segment is 2.2R; where R > 0.

[0012] Further, the cross-sectional shape of the tooth rib structure includes a connected first isosceles trapezoid and a second isosceles trapezoid; the first isosceles trapezoid is located on the side close to the tooth root of the second isosceles trapezoid; the lower base of the first isosceles trapezoid is close to the tooth root side, the upper base of the first isosceles trapezoid is connected to the lower base of the second isosceles trapezoid, and the upper base of the second isosceles trapezoid is located on the side close to the tooth tip; the length of the lower base of the first isosceles trapezoid is greater than the length of the upper base of the first isosceles trapezoid, the length of the lower base of the second isosceles trapezoid is greater than the length of the upper base of the second isosceles trapezoid, and the length of the upper base of the first isosceles trapezoid is equal to the length of the lower base of the second isosceles trapezoid.

[0013] Further, the cross-sectional shape of the tooth groove includes a connected first cross-sectional shape and a second cross-sectional shape. The first cross-sectional shape is arranged close to the bottom of the tooth groove. The first cross-sectional shape is a structure with a wider upper part and a narrower lower part or a rectangular structure with equal width up and down. Wherein, the side close to the bottom of the tooth groove is the lower side; the length of the lower base of the first isosceles trapezoid is L1, the length of the lower base of the second isosceles trapezoid is L2, and L1 > L2;

[0014] Where H is the height of the first isosceles trapezoid, and m is the number of tooth ribs that should be had if the arc segment is a complete circumference, reflecting the tooth rib density of the arc segment.

[0015] Further, the cross-sections of multiple tooth rib structures form multiple tooth-shaped surfaces. At least some of the multiple tooth-shaped surfaces meet the following requirements: from the midpoint of the tooth bottom of the tooth-shaped surface to the midpoint of the tooth tip, a first vector is formed, and from the center of the first arc segment to the center of the third arc segment, a second vector is formed. The angle between the first vector and the second vector is less than 90°.

[0016] According to the second aspect of the present utility model, a permanent magnet motor is further provided. The permanent magnet motor includes: a rotor core, on which a plurality of mounting holes are provided. Each mounting hole penetrates through the axial two ends of the rotor core, and the plurality of mounting holes are arranged at intervals in the circumferential direction of the rotor core; a plurality of special-shaped heat pipes for improving the heat dissipation of the permanent magnet rotor, and the plurality of special-shaped heat pipes are respectively mounted in the plurality of mounting holes one by one. The special-shaped heat pipe for improving the heat dissipation of the permanent magnet rotor is the above-mentioned special-shaped heat pipe for improving the heat dissipation of the permanent magnet rotor; a refrigerant is filled in each special-shaped heat pipe; wherein, the shape of the mounting hole is adapted to the shape of the special-shaped heat pipe, and the length of the special-shaped heat pipe is greater than the length of the rotor core; after installation, the third arc segment of the special-shaped heat pipe is closer to the axis of the rotor core than the first arc segment, and the cross-section of each special-shaped heat pipe is symmetric along the radial line of the rotor core; both ends of each special-shaped heat pipe extend outside the rotor core, and the lengths extending outside the rotor core are equal.

[0017] Applying the technical solution of the present utility model, the cross-sectional shape of the outer peripheral wall of the heat pipe is optimized, including a first arc segment, a second arc segment, a third arc segment and a fourth arc segment connected in sequence from head to tail, and is arranged in a gourd shape, which is beneficial to increasing the contact area between the heat pipe and the heat source, thereby being beneficial to improving the cooling effect and effectively improving the heat exchange efficiency.

[0018] In addition, the gourd-shaped cross-section is also beneficial to reducing the use of refrigerant and improving the centripetal force burden caused by the high-speed rotation of the rotor core. Compared with the circular heat pipe, the gourd-shaped special-shaped heat pipe of the special-shaped heat pipe increases the effective contact area of the inner peripheral wall, especially increases the curvature of the first arc. When using the same amount of refrigerant, the refrigerant deposited in the inner peripheral wall of the first arc region of the special-shaped heat pipe will obtain a larger inner peripheral wall contact area compared with the circular heat pipe with the equivalent radius of the special-shaped heat pipe. Therefore, less refrigerant use can obtain the same heat exchange effect, thereby reducing the use of refrigerant. At the same time, the special-shaped heat pipes are arranged in the position section of the rotor core at the same distance from the axis, and the centroid of the cross-section of the special-shaped heat pipe is closer to the axis of the rotor. After considering adding less refrigerant, the centroid of the special-shaped heat pipe is closer to the axis than the circular heat pipe with the equivalent radius when the motor rotates.

[0019] At the same time, the present application also optimizes the structure of the inner peripheral wall of the special-shaped heat pipe. After optimization, a plurality of spaced protruding tooth rib structures are provided on the inner peripheral wall of the special-shaped heat pipe, and a tooth groove is formed between adjacent two tooth rib structures. This structure can improve the capillary force compared with the traditional sintered or mesh liquid absorption structure, so as to enhance the adsorption and reflux effect of the refrigerant. The plurality of protruding tooth ribs provide a large number of tooth rib surfaces, which can greatly increase the heat exchange contact area of the refrigerant medium in the pipe, perform excellently under high heat flux conditions, and have better heat dissipation effect. The tooth rib structure and the special-shaped heat pipe are manufactured as a whole, having better structural stability and being able to withstand greater thermal stress and mechanical stress.

[0020] In addition, the overall shape of the special-shaped heat pipe in this application is optimized. After optimization, the first pipe section and the second pipe section are arranged in a V shape. This design can accelerate the rate at which the liquefied refrigerant in the condensation areas at both ends flows back into the rotor core. When the motor rotates at an angular velocity ω, the V-shaped structure will generate centripetal acceleration components along the first pipe section and the second pipe section, which is ω 2 rsinθ, where r is the distance from the rotor axis to the centroid of the special-shaped heat pipe. The liquefied refrigerant will be affected by the capillary force to flow back and also by the component acceleration, thus accelerating the backflow.

[0021] Based on the implementation manners provided in the above aspects of this application, further combinations can be made to provide more implementation manners. Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 Schematic three-dimensional structure diagram of the special-shaped heat pipe provided by an optional embodiment of this application;

[0024] Figure 2 For Figure 1 partial cross-sectional schematic diagram;

[0025] Figure 3 For Figure 1 front cross-sectional schematic diagram;

[0026] Figure 4 For Figure 3 partial enlarged view;

[0027] Figure 5 For Figure 1 enlarged structural schematic diagram of a partial tooth ridge structure and tooth groove of the special-shaped heat pipe in;

[0028] Figure 6 Schematic assembly structure diagram of the rotor core of the permanent magnet motor and the special-shaped heat pipe;

[0029] Figure 7 For Figure 1 circulation principle diagram of the special-shaped heat pipe in;

[0030] Figure 8 Magnetic induction line distribution diagram after introducing the special-shaped heat pipe into the rotor of this motor;

[0031] Explanation of the reference numerals in the drawings:

[0032] 1. Rotor core; 11. Mounting hole; 2. Special-shaped heat pipe; 101. First arc segment; 102. Second arc segment; 103. Third arc segment; 104. Fourth arc segment; 501. Tooth edge structure; 7. First isosceles trapezoid; 8. Second isosceles trapezoid; 502. Tooth groove; 111. First cross-sectional shape; 112. Second cross-sectional shape; 6. Tooth-shaped surface; 100. First pipe segment; 110. First straight segment; 200. Second pipe segment; 120. Second straight segment; 300. Interface; 10. First enclosing plate; 20. Second enclosing plate; 30. First end plate; 40. Second end plate; 50. Partition; 9. Capillary structure tooth-shaped ridge; 13. Condensing area. Detailed implementation manners

[0033] In order to enable those skilled in the art of this technology to better understand the solution of this utility model, the technical solutions in the embodiments of this utility model will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this utility model. Obviously, the described embodiments are only a part of the embodiments of this utility model, rather than all of the embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the scope of protection of this utility model. Unless otherwise specified, the technical means used in the embodiments are conventional means well-known to those skilled in the art.

[0034] As Figures 1 to 8 shown, an optional embodiment of this utility model provides a special-shaped heat pipe for improving the heat dissipation of a permanent magnet rotor. The cross-section of the outer peripheral wall of the special-shaped heat pipe 2 includes a first arc segment 101, a second arc segment 102, a third arc segment 103, and a fourth arc segment 104 that are connected in sequence from head to tail. The centers of the first arc segment 101 and the third arc segment 103 are on a straight line. The radius of the first arc segment 101 is smaller than the radius of the third arc segment 103. The two ends of the second arc segment 102 are respectively tangent to the first end of the first arc segment 101 and the first end of the third arc segment 103. The two ends of the fourth arc segment 104 are respectively tangent to the second end of the first arc segment 101 and the second end of the third arc segment 103. The centers of the first arc segment 101 and the third arc segment 103 are located inside the special-shaped heat pipe 2, and the centers of the second arc segment 102 and the fourth arc segment 104 are located outside the special-shaped heat pipe 2; a plurality of spaced-apart protruding tooth edge structures 501 are provided on the inner peripheral wall of the special-shaped heat pipe 2, and tooth grooves 502 are formed between adjacent two tooth edge structures 501; along the length direction of the special-shaped heat pipe 2, the special-shaped heat pipe 2 includes a connected first pipe segment 100 and a second pipe segment 200, and the first pipe segment 100 and the second pipe segment 200 are arranged at an angle.

[0035] The present application optimizes the cross-sectional shape of the outer peripheral wall of the special-shaped heat pipe 2, which includes a first arc segment 101, a second arc segment 102, a third arc segment 103, and a fourth arc segment 104 connected in sequence from beginning to end, and is arranged in a gourd shape, which is beneficial to increasing the contact area between the special-shaped heat pipe 2 and the heat source, thereby being beneficial to improving the cooling effect and effectively improving the heat exchange efficiency.

[0036] In addition, the gourd-shaped cross-section is also beneficial to reducing the use of refrigerant and improving the centripetal force burden caused by the high-speed rotation of the rotor core 1. Compared with the circular heat pipe, the gourd-shaped special-shaped heat pipe increases the effective contact area of the inner peripheral wall, especially increases the curvature of the first arc. When the same amount of refrigerant is used, the refrigerant deposited on the inner peripheral wall of the first arc region of the special-shaped heat pipe will obtain a larger inner peripheral wall contact area compared with the circular heat pipe with an equivalent radius of the special-shaped heat pipe. Therefore, the same heat exchange effect can be obtained with less refrigerant use, thereby reducing the use of refrigerant. At the same time, the special-shaped heat pipes are arranged at the position section where the rotor core is at the same distance from the axis, and the centroid of the cross-section of the special-shaped heat pipe is closer to the rotor axis. After considering adding less refrigerant, the centroid of the special-shaped heat pipe is closer to the axis than that of the circular heat pipe with an equivalent radius during the rotation of the motor.

[0037] At the same time, the present application also optimizes the structure of the inner peripheral wall of the special-shaped heat pipe 2. After optimization, a plurality of spaced-apart protruding tooth-ridge structures 501 are provided on the inner peripheral wall of the special-shaped heat pipe 2, and a tooth groove 502 is formed between adjacent tooth-ridge structures. Compared with the traditional sintered or mesh liquid-absorbing structure, this tooth-ridge structure can improve the capillary force to enhance the adsorption and reflux effects of the refrigerant. The plurality of protruding tooth-ridges provide more tooth-ridge surfaces, which can greatly increase the heat exchange contact area of the refrigerant medium in the pipe, perform well under high heat flux conditions, and have a better heat dissipation effect. The tooth-ridge structure and the special-shaped heat pipe are manufactured as a whole, having better structural stability and being able to withstand greater thermal stress and mechanical stress.

[0038] In addition, the present application also optimizes the overall shape of the special-shaped heat pipe 2. After optimization, the first pipe section 100 and the second pipe section 200 are arranged in a V shape, and this design can accelerate the rate of the liquefied refrigerant in the two end condensation zones to flow back into the rotor core. When the motor rotates at an angular velocity ω, the V-shaped structure will generate a centripetal acceleration component along the first pipe section and the second pipe section, which is ω 2 rsinθ, where r is the distance between the rotor axis and the centroid of the special-shaped heat pipe. The liquefied refrigerant will be affected by the centripetal acceleration while being refluxed by the capillary force, thereby accelerating the reflux.

[0039] Optionally, as Figure 2 and Figure 3As shown, the straight line where the center of the first arc segment 101 and the center of the third arc segment 103 are located forms a reference line, and the second arc segment 102 and the fourth arc segment 104 are symmetrically arranged with respect to the reference line.

[0040] Optionally, as Figure 1 shown, the plane where the junction of the first pipe segment 100 and the second pipe segment 200 is located forms an interface 300, and the first pipe segment 100 and the second pipe segment 200 are symmetrically arranged with respect to the interface 300.

[0041] Since the special-shaped heat pipe 2 is a rotating structure, ensuring the symmetry of the structural layout is beneficial to ensuring its stability during rotation.

[0042] Optionally, as Figure 1 shown, the quadrant point of the third arc segment 103 located on the reference line forms a reference point; the outer peripheral wall of the first pipe segment 100 includes a first straight line segment 110 passing through the reference point; the outer peripheral wall of the second pipe segment 200 includes a second straight line segment 120 passing through the reference point; the first straight line segment 110 intersects with the second straight line segment 120, and the included angle between the first straight line segment 110 and the second straight line segment 120 is θ, and the value range of θ is greater than or equal to 175 degrees and less than 180 degrees. There are restrictions on the radial region where the special-shaped heat pipe can be set from the permanent magnet around the rotor core to the rotor axis. Radially, it does not exceed the permanent magnet and the rotor shaft. When the first straight line segment and the second straight line segment of the special-shaped heat pipe are axially symmetrically arranged on the rotor core and the cross-section of the special-shaped heat pipe is radially symmetrically arranged, the included angle θ should not be too small. And too small an included angle will cause too large a change in the axial structural distribution of the rotor, making the interface too far from the axis and the two ends too close to the axis. This change will make the rotational mechanical stability worse. At the same time, the uniformity of the electromagnetic field characteristics distribution of the rotor core in the axial direction becomes worse. Based on engineering experience, the included angle θ is set within the above value range.

[0043] Optionally, as Figures 2 to 4 shown, along the length direction of the special-shaped heat pipe 2, multiple spaced tooth-ridge structures 501 on the inner peripheral wall of the first pipe segment 100 and multiple spaced tooth-ridge structures 501 on the inner peripheral wall of the second pipe segment 200 both extend to the interface 300; the multiple tooth-ridge structures 501 on the inner peripheral wall of the first pipe segment 100 and the multiple tooth-ridge structures 501 on the inner peripheral wall of the second pipe segment 200 are symmetrically arranged with respect to the interface 300. The rotating structure should ensure the symmetry of the structural layout. Therefore, the tooth-ridge structure of the special-shaped heat pipe should extend to the interface, which not only maximizes the tooth-ridge surface area of the tooth-ridge structure, thus making the heat exchange area of the refrigerant the largest, but also the distribution extending to the interface has the characteristic of symmetrical arrangement.

[0044] Optionally, as Figure 1 and Figure 7As shown in the figure, the special-shaped heat pipe 2 includes a first enclosing plate 10 arranged in a ring shape, a second enclosing plate 20 arranged in a ring shape, a first end plate 30, a second end plate 40 and a partition plate 50; the second end of the first enclosing plate 10 is connected to the first end of the second enclosing plate 20, the first end plate 30 is connected to the first end of the first enclosing plate 10, the second end plate 40 is connected to the second end of the second enclosing plate 20, and the partition plate 50 is arranged at the junction of the first enclosing plate 10 and the second enclosing plate 20; a first pipe section 100 formed by the first enclosing plate 10, the first end plate 30 and the partition plate 50, and a second pipe section 200 formed by the second enclosing plate 20, the second end plate 40 and the partition plate 50. A first closed space for filling refrigerant is provided in the first pipe section 100, and a second closed space for filling refrigerant is provided in the second pipe section 200. The two closed spaces work independently, and the amount of refrigerant added can be adjusted according to the different heating conditions of the rotor core in the regions of the first pipe section and the second pipe section of the structure under actual working conditions, so as to improve the heat dissipation capacity.

[0045] Optionally, as Figure 3 shown, the radius of the first arc segment 101 is R; the radius of the third arc segment 103 is 2R; the radii of the second arc segment 102 and the fourth arc segment 104 are both 2R; the distance between the centers of the first arc segment 101 and the third arc segment 103 is 2.2R; where R > 0. In this way, on the premise of ensuring the advantages of less refrigerant usage, smaller centripetal force, and larger refrigerant heat exchange area compared with the same round pipe, the curvature change of the cross-sectional profile of the special-shaped heat pipe can be made more uniform and not too large locally, which is beneficial to the improvement of the following magnetic field distribution. Theoretically, the larger the center distance, the longer the second arc segment and the fourth arc segment, and the more and more beneficial the tooth edge structure in their regions is for heat dissipation, but it will cause the shortest straight-line distance between the second arc segment and the fourth arc segment to become smaller, that is, narrower. At this time, the channel connecting the inner cavities of the first arc region and the third arc region of the special-shaped heat pipe becomes narrower, which will not be conducive to the phase change heat transfer of the refrigerant in the special-shaped heat pipe. At the same time, if the special-shaped heat pipe is too long in the radial direction, it will also exceed the limit of the radial region where the special-shaped heat pipe can be set from the permanent magnet around the rotor core to the rotor axis. Considering comprehensively, it is a more reasonable specification to set the center distance to 2.2R. The value of R is related to the size of the motor rotor core. On the premise of not affecting the mechanical and electromagnetic characteristics of the rotor after introducing the special-shaped heat pipe, the value of R tends to increase.

[0046] Optionally, as Figure 5As shown in the figure, the cross-sectional shape of the tooth edge structure 501 includes a connected first isosceles trapezoid 7 and a second isosceles trapezoid 8; the first isosceles trapezoid 7 is located on the side close to the tooth root of the second isosceles trapezoid 8; the lower base of the first isosceles trapezoid 7 is close to the tooth root side, the upper base of the first isosceles trapezoid 7 is connected to the lower base of the second isosceles trapezoid 8, and the upper base of the second isosceles trapezoid 8 is located on the side close to the tooth tip; the length of the lower base of the first isosceles trapezoid 7 is greater than the length of the upper base of the first isosceles trapezoid 7, the length of the lower base of the second isosceles trapezoid 8 is greater than the length of the upper base of the second isosceles trapezoid 8, and the length of the upper base of the first isosceles trapezoid 7 is equal to the length of the lower base of the second isosceles trapezoid 8. In this way, without increasing the manufacturing difficulty, there is no sudden reduction in the local thickness in each area of the tooth edge structure, and its structural strength can be guaranteed. When the motor runs non-uniformly or high-order magnetic harmonics are generated on the rotor, the tooth edge structure can resist the stress deformation caused by the acceleration torque and harmonic electromagnetic torque.

[0047] Optionally, as Figure 5 shown, the cross-sectional shape of the tooth groove 502 includes a connected first cross-sectional shape 111 and a second cross-sectional shape 112. The first cross-sectional shape 111 is arranged close to the bottom of the tooth groove 502. The first cross-sectional shape 111 is a structure with a wider upper part and a narrower lower part or a rectangular structure with equal width up and down. Among them, the side close to the bottom of the tooth groove 502 is the lower part; the shape of the second cross-sectional shape 112 is controlled by the first isosceles trapezoid and the second isosceles trapezoid, and no special limitation is made here.

[0048] The generation of the first cross-sectional shape 111 is affected by the size relationship between L1 and L2 and is passive. When selecting the values of L1 and L2, it should be ensured that the first cross-sectional shape 111 does not appear in the situation of a narrower upper part and a wider lower part. The lower base of the first cross-sectional shape 111 refers to the bottom close to the tooth root, and the upper base refers to the bottom connected to the first cross-sectional shape 111. The first cross-sectional shape 111 is the main part of the tooth groove of the tooth edge structure, and it should be ensured that it is a structure with a wider upper part and a narrower lower part or a rectangular structure with equal width up and down. This is an open shape, which is conducive to attaching the liquefied refrigerant. If it shows a narrower upper part and a wider lower part, this is a sealed shape, which will not be conducive to the attachment of the liquefied refrigerant. Since the shape of the second cross-sectional shape is controlled by the first isosceles trapezoid and the second isosceles trapezoid, it is passive.

[0049] Optionally, as Figure 5 shown, the length of the lower base of the first isosceles trapezoid 7 is L1, the length of the lower base of the second isosceles trapezoid 8 is L2, and L1 > L2; where H is the height of the first isosceles trapezoid 7, and m is the number of tooth edges that should be available if the arc segment is a complete circumference, reflecting the tooth edge density of the arc segment. In this way, the requirement that the first cross-sectional shape 111 does not appear in the situation of a narrower upper part and a wider lower part can be met.

[0050] Optionally, as Figure 4As shown, the cross-sections of multiple tooth edge structures 501 form multiple tooth-shaped surfaces 6, and at least some of the multiple tooth-shaped surfaces 6 meet the following requirements: A first vector is formed by pointing from the midpoint of the tooth bottom of the tooth-shaped surface 6 to the midpoint of the tooth top, and a second vector is formed by pointing from the center of the first arc segment 101 to the center of the third arc segment 103. The included angle γ between the first vector and the second vector is less than 90°.

[0051] Optionally, the tooth-shaped surfaces 6 of the tooth edge structures 501 in the region where the second arc segment 102, the fourth arc segment 104, and part of the third arc segment 103 connected to the second arc segment 102 and the fourth arc segment 104 are located meet the above requirements. That is, in the direction from the tooth bottom to the tooth top of the tooth edge surface of part of the tooth-shaped structure, the included angle γ with the direction from the center of the first arc segment 101 to the center of the second arc segment 102 is less than 90°.

[0052] When the included angle γ of part of the tooth-shaped surfaces is less than 90°, it can be ensured that when the liquefied refrigerant is adsorbed in the corresponding tooth grooves, a component force along the tooth groove direction will be generated by the centripetal force in the radial direction during the rotation of the motor. This component force helps the liquefied refrigerant to be adsorbed in the tooth grooves, thereby increasing the contact area between the refrigerant and the inner wall of the special-shaped heat pipe and the capillary structure, and thus improving the heat transfer efficiency.

[0053] As Figure 6 shown, the present utility model also provides a permanent magnet motor, which includes: a rotor core 1, and a plurality of mounting holes 11 are further provided on the rotor core 1. Each mounting hole 11 penetrates through the axial two ends of the rotor core 1, and the plurality of mounting holes 11 are arranged at intervals in the circumferential direction of the rotor core 1; a plurality of special-shaped heat pipes 2 for improving the heat dissipation of the permanent magnet rotor are provided, and the plurality of special-shaped heat pipes 2 are respectively mounted in the plurality of mounting holes 11 one by one. The special-shaped heat pipes 2 for improving the heat dissipation of the permanent magnet rotor are the above-mentioned or the following special-shaped heat pipes 2 for improving the heat dissipation of the permanent magnet rotor; a refrigerant is filled in each special-shaped heat pipe 2; wherein, the shape of the mounting hole 11 is adapted to the shape of the special-shaped heat pipe 2, and the length of the special-shaped heat pipe 2 is greater than the length of the rotor core 1; after installation, the third arc segment 103 of the special-shaped heat pipe 2 is closer to the axis of the rotor core 1 than the first arc segment 101, and the cross-sections of the special-shaped heat pipes 2 are all symmetric along the radial line of the rotor core 1; both ends of each special-shaped heat pipe 2 extend out of the rotor core 1, and the lengths extending out of the rotor core 1 are equal. In this way, by applying the optimized special-shaped heat pipe 2 in the permanent magnet motor and cooperating with the rotor core 1, the special-shaped heat pipe 2 can take away the heat generated by the rotor core 1 and has a better cooling effect.

[0054] Currently, the mainstream structure of the permanent magnet motor is that a V-shaped permanent magnet is installed on the rotor core 1. Therefore, the present application provides a typical embodiment. As Figure 6 shown, the special-shaped heat pipe provided by the present application is cooperated with the rotor core 1 installed with the V-shaped permanent magnet.

[0055] In an alternative embodiment not shown in the present application, a linear or multi-layer V-shaped permanent magnet may also be installed on the rotor core 1. As long as it is within the radial limit of the rotor core, that is, not exceeding the area of the permanent magnet and the rotor shaft, and without affecting the structural strength of the rotor core and the requirements of the magnetic field distribution, this type of special-shaped heat pipe can be arranged in existing types of permanent magnet motors.

[0056] The rotor core is axially assembled from numerous relatively thin silicon steel sheets and welded into one body after assembly. During manufacturing or maintenance, assembly holes for installing permanent magnets and installation holes 11 for installing special-shaped heat pipes can be pre-opened. It should be noted that due to the V shape of the special-shaped heat pipe, along the axial direction, the radial distance of the installation holes 11 from the axis on each silicon steel sheet is different. The interface is the farthest, and the silicon steel sheets on the front and rear end faces are the closest. Along the axis from the interface to the end face of the rotor core, the radial distance of the installation holes 11 from the axis decreases in a gradient. Each silicon steel sheet should determine the radial distance of the installation holes 11 from the axis according to its assembled position.

[0057] The following gives the first assembly method: It should be noted that neither the silicon steel sheet nor the special-shaped heat pipe is absolutely rigid, and both have certain elasticity and deformation ability. At the same time, the fit between the installation holes 11 and the special-shaped heat pipe is not airtight, so there is a certain margin of movement when the special-shaped heat pipe penetrates into the silicon steel sheet. First, insert the second pipe segments of all special-shaped heat pipes into all the silicon steel sheets arranged in the established position and order in their respective areas. The special-shaped heat pipe is longer than the axial length of the rotor core, so all the silicon steel sheets on the second pipe segment can move between the interface of the special-shaped heat pipe and the end of the special-shaped heat pipe. The installation holes 11 of the silicon steel sheets arranged closer to the interface in the first pipe segment area are farther away. Since the ends of all the special-shaped heat pipes at the end of the first pipe segment are circumferentially evenly arranged and closer to the axis. In order to insert the silicon steel sheets of the first pipe segment into the first pipe segment in sequence, first move all the silicon steel sheets of the second pipe segment towards the end of the second pipe segment. At this time, the radial distance of the ends of all the special-shaped heat pipes circumferentially evenly arranged at the end of the first pipe segment from the axis will increase, so as to facilitate the insertion of the silicon steel sheets in the first pipe segment area closer to the interface. And so on, by flexibly moving all the silicon steel sheets of the second pipe segment, changing the radial distance of all the special-shaped heat pipes in the first pipe segment, and inserting the silicon steel sheets from the one closer to the interface to the end in sequence to complete the assembly.

[0058] The second assembly method: Arrange all the silicon steel sheets in the areas where the first pipe section and the second pipe section are located in sequence and fix them softly to form two groups. Arrange all the special-shaped heat pipes circumferentially and evenly according to the established arrangement method, and increase the radial distance of each special-shaped heat pipe from the axis so that the radial distances of the ends of the first pipe section and the second pipe section from the axis are the same as the radial distances of the mounting holes 11 of the silicon steel sheets at the interface from the axis. At this time, insert the two groups of silicon steel sheets from both ends simultaneously. Under the guidance of the channels formed by the mounting holes 11 where the special-shaped heat pipes are angled with the silicon steel sheet groups in the axial direction, the special-shaped heat pipes return to the established positions passively to complete the assembly. After the assembly is completed, weld the silicon steel sheets, and fill silicon grease, liquid metal or other heat-conducting materials into the gaps of the rotor mounting holes 11.

[0059] In an alternative embodiment of the present utility model, as Figures 1 to 8 shown, a special-shaped heat pipe 2 for dissipating heat from the rotor core 1 of a permanent magnet motor is provided, and this structure includes a special-shaped surface, a tooth-shaped capillary structure and a "V" - shaped structure.

[0060] The special-shaped heat pipe 2 is a symmetric "V" - shaped structure with an included angle of θ, where θ ∈ [175°, 180°), and the outer cross - section of the special-shaped heat pipe 2 presents a "gourd" - shaped structure. The inner wall of the special-shaped heat pipe 2 adopts a tooth - shaped ribbed capillary structure, which extends along the direction of the special-shaped heat pipe 2 to the symmetric center plane. The ribbed tooth - shaped capillary structure is evenly distributed on the inner wall of the special-shaped heat pipe 2 and is symmetric about the central symmetry plane of the "V" - shaped structure.

[0061] The special-shaped heat pipe 2 is a closed structure.

[0062] Furthermore, regarding the "gourd" - shaped special-shaped cross - section, the radius of the "big circle" is 2R, that is, the radius of the third arc segment 103 is 2R; the radius of the "small circle" is R, that is, the radius of the first arc segment 101 is R; the radii of the two symmetric arc tangents tangent to the big and small circles are also 2R, that is, the radii of the second arc segment 102 and the fourth arc segment 104 are both 2R; the center distance between the "big circle" and the "small circle" is 2.2R.

[0063] Theoretically, the larger the center distance, the longer the second arc segment and the fourth arc segment, and the more and better the tooth - rib structures in their areas are for heat dissipation. However, it will cause the shortest straight - line distance between the second arc segment and the fourth arc segment to become smaller, that is, narrower. At this time, the channel connecting the inner cavities of the first arc region and the third arc region of the special-shaped heat pipe becomes narrower, which is not conducive to the phase - change heat transfer of the refrigerant in the special-shaped heat pipe. At the same time, if the special-shaped heat pipe is too long in the radial direction, it will also exceed the limit of the radial region where the special-shaped heat pipe can be set from the permanent magnet around the rotor core to the rotor axis. Considering comprehensively, setting the center distance to 2.2R is a more reasonable specification.

[0064] The value of R is related to the size of the motor rotor core. On the premise of not affecting the mechanical and electromagnetic characteristics of the rotor after introducing the special-shaped heat pipe, the value of R tends to increase.

[0065] Preferably, the tooth-shaped ribbed capillary structure, that is, the cross-section of the tooth rib structure 501 is a tooth-shaped surface 6, the part close to the tooth root is the first isosceles trapezoid 7, and the part close to the tooth top is the second isosceles trapezoid 8; the shape of the cross-section of the tooth groove 502 includes a rectangle in the part close to the tooth root and a third isosceles trapezoid in the part close to the tooth top.

[0066] Furthermore, the included angle between the numerous tooth-shaped surfaces 6 and the direction from the center of the "small circle" to the center of the "big circle" is less than 90°.

[0067] The following further elaborates on a specific embodiment of the present invention in conjunction with the accompanying drawings.

[0068] As Figure 1 shown, the special-shaped heat pipe 2 is in a "V" shape in the length direction, the included angle θ is 175°, the bending direction is on the "big circle" side, and it is symmetric about the central plane, that is, symmetric with respect to the interface 300, and the special-shaped heat pipe 2 is an overall sealed structure.

[0069] As Figure 2 and Figure 3 shown, the cross-section of the special-shaped heat pipe 2 is in a "gourd" shape, the radius of the "big circle" is 2R, that is, the radius of the third arc segment 103 is 2R; the radius of the "small circle" is R, that is, the radius of the first arc segment 101 is R; the radius of the arc tangent connecting the large and small circles of the cross-section is 2R, which is tangent to the large and small circles of the "gourd" shape, and the left and right arc tangents are symmetric, that is, the radii of the second arc segment 102 and the fourth arc segment 104 are both 2R, the two ends of the second arc segment 102 are respectively tangent to the first arc segment 101 and the third arc segment 103, the two ends of the fourth arc segment 104 are respectively tangent to the first arc segment 101 and the third arc segment 103, and the second arc segment 102 and the fourth arc segment 104 are symmetric; the distance between the centers of the large and small circles of the cross-section of the special-shaped heat pipe 2 is 2.2R, that is, the distance between the center of the first arc segment 101 and the center of the third arc segment 103 is 2.2R.

[0070] As Figure 3 and Figure 5As shown, the special-shaped heat pipe 2 has a certain thickness, and on the inner side of the special-shaped heat pipe 2, tooth-shaped ribbed capillary structures, namely tooth rib structures 501, are evenly distributed. The tooth-shaped surface 6 is a combination of a first isosceles trapezoid 7 and a second isosceles trapezoid 8. The part close to the tooth root is the first isosceles trapezoid 7, and the part close to the tooth top is the second isosceles trapezoid 8. The tooth-shaped surface 6 extends along the axis direction of the special-shaped heat pipe 2 into a capillary structure tooth rib ridge 9, and extends to the "V"-shaped symmetry center plane, that is, extends to the interface 300. On the other side of the interface 300, the shape of the capillary structure is the same as that on this side, and the distribution is symmetric about the interface 300. The tooth rib structure 501 replaces the liquid absorption core part of the conventional special-shaped heat pipe. Compared with the traditional sintered or mesh liquid absorption structure, this tooth rib structure can improve the capillary force to enhance the adsorption and reflux effects of the refrigerant. Multiple protruding tooth ribs provide more tooth rib surfaces, which can greatly increase the heat exchange contact area of the refrigerant medium in the pipe, perform excellently under high heat flux conditions, and have a better heat dissipation effect. The tooth rib structure and the special-shaped heat pipe are manufactured as a whole, with better structural stability and can withstand greater thermal stress and mechanical stress.

[0071] As Figure 5 shown, a large number of tooth-shaped ribbed capillary structures on both sides are evenly arranged along the circumferences of the "small circle", "large circle" and the tangent line of the arc, and each tooth-shaped ribbed capillary structure is axisymmetric about the radial line of the "small circle", "large circle" and the tangent line of the arc in the region where it is located. The spacing of each tooth-shaped ribbed capillary structure is the same as the tooth root width of the capillary structure tooth rib ridge 9, which is L1. In the transition region where the "small circle" and the tangent line of the arc, and the "large circle" and the tangent line of the arc are connected, the spacing does not have to be L1, but is determined according to the coherence of the arrangement of the tooth rib ridges.

[0072] The lower base and the upper base of the first isosceles trapezoid 7, which is the main part of the tooth-shaped surface 6, are L1 and L3 respectively. L3 must be less than L1, and their ratio is not fixed, but it is necessary to make the tooth groove 502 between the capillary structures wider at the top and narrower at the bottom or equal in width from top to bottom, and should not be narrower at the top and wider at the bottom. Here, "top" refers to the region close to the upper base of the first isosceles trapezoid 7, and "bottom" refers to the region close to the lower base of the first isosceles trapezoid 7.

[0073] As Figure 7 shown, the special-shaped heat pipe 2 is filled with an evaporable and phase-changing liquid refrigerant.

[0074] The distribution of the special-shaped heat pipe 2 in the permanent magnet rotor core 1 is as Figure 6As shown, the number n of the special-shaped heat pipes 2 is greater than 1, and they are evenly arranged circumferentially on the inner side close to the axis. In the longitudinal direction, they are in a "V" shape. Both sides of the "V" shape are symmetric about the interface 300, and the symmetric ends form an angle of 2.5° with the axis. Each special-shaped heat pipe 2 is symmetric about the radial line in the radial direction. Therefore, the centers of the large and small circles coincide with the radial line. The "small circle" of the cross-section is far from the axis of the rotor core 1, and the "large circle" is close to the axis of the rotor core 1. The special-shaped heat pipes 2 are longer than the rotor core 1, and the extended part is provided with the condensation area 13 of the special-shaped heat pipes 2.

[0075] The special-shaped heat pipes 2 embedded in the rotor core 1 are radially symmetric. The "small circle" of the "gourd"-shaped special-shaped heat pipes 2 is far from the axis, and the "large circle" is close to the axis. The large and small circles are connected by an arc. This layout can reduce the amount of refrigerant used. And when the motor runs at high speed, the less refrigerant in the "small circle" can improve the centripetal force pressure of the motor. When the refrigerant cools and liquefies, it can be adsorbed by the tooth-shaped capillary structure and flow towards the inside of the rotor core 1. The included angle between the numerous tooth-shaped surfaces 6 and the direction from the center of the "small circle" to the center of the "large circle" is less than 90°. This structural layout ensures that when the motor rotates at high speed or operates complexly, in addition to relying on capillary force, the cooled liquid refrigerant can be attached to the inner wall of the special-shaped heat pipes 2 and in the tooth grooves 502 as much as possible under the action of centripetal force, thereby increasing the effective area of phase change evaporation and heat absorption of the special-shaped heat pipes 2, and thus improving the heat transfer efficiency.

[0076] When the permanent magnet around the rotor core 1 of the motor or the local part of the iron core is overheated, the refrigerant in the special-shaped heat pipes 2 absorbs heat and turns into gas. There is a temperature difference between the gas and the condensation area 13 extending out of the rotor core 1, and it flows towards the condensation area for condensation under the action of convective heat transfer caused by the temperature difference. After condensation, the refrigerant medium liquefies, and a part of it is adsorbed in the grooves of the tooth-shaped capillary structure, and another part accumulates in the "small circle" of the special-shaped heat pipes 2. Under the action of capillary force and the axial component of the centripetal force of the motor rotation, both parts of the refrigerant return to the inside of the rotor core 1 and near the permanent magnet for the next heat transfer cycle. This is the working process of the special-shaped heat pipes 2 in one cycle, and the circulation process is as Figure 7 shown, the solid line is the flow of the gas phase, and the dotted line is the reflux of the condensed liquid phase.

[0077] The special-shaped heat pipes 2 of the present invention are special-shaped heat pipes 2 dedicated to the heat dissipation of the rotor core 1 of the permanent magnet motor, and are applicable to the rotor core 1 with a "V"-shaped permanent magnet distribution. This structure takes into account the magnetic circuit distribution of the rotor core 1 and restricts the shape of the special-shaped heat pipes 2 so as to better fit the direction of the magnetic induction lines, so that the heat dissipation layout generates less magnetic resistance and magnetic leakage to the rotor core 1. The "gourd"-shaped cross-sectional structure is beneficial to reducing the use of refrigerant, improving the centripetal force burden caused by the high-speed rotation of the rotor core 1, and at the same time increasing the contact area with the heat source, effectively improving the heat exchange efficiency.

[0078] The beneficial technical effects of the present invention at least include;

[0079] This special-shaped heat pipe 2 is a dedicated special-shaped heat pipe for dissipating heat from the rotor core 1 of a permanent magnet motor and is applicable to the rotor core 1 with a "V"-shaped permanent magnet distribution.

[0080] The structure of this special-shaped heat pipe 2 takes into account the magnetic circuit distribution of the rotor core 1, and restricts the layout and shape of the special-shaped heat pipe 2 so as to better fit the direction of the magnetic induction lines, minimizing the magnetic resistance and magnetic leakage generated by the heat dissipation layout on the rotor core 1.

[0081] The silicon steel sheet of the rotor has an upper limit of magnetic flux density, that is, magnetic saturation. When magnetic saturation is reached, the magnetic resistance and hysteresis loss increase, resulting in an increase in heat generation. This causes non-linear distortion, generates high-order harmonics, causes motor jitter, and local electromagnetic forces are generated on the rotor. Mechanical stress will be generated in this part of the area, affecting mechanical stability. At the same time, when the magnetic flux density reaches the upper limit, more magnetic leakage will be generated. Magnetic leakage will also generate hysteresis loss and eddy current loss, increasing heat generation, and reducing the torque output and power factor of the motor. The narrowing of the magnetic channel and the increase in the curvature of the local magnetic circuit are the main reasons for magnetic saturation. As Figure 8 shown, it is the magnetic induction line distribution diagram of this motor rotor after introducing this special-shaped heat pipe. Due to the layout position of the special-shaped heat pipe and the large curvature of the first arc segment, the narrowing of the magnetic flux and the increase in local curvature after introducing the special-shaped heat pipe are greatly inhibited. Therefore, the magnetic induction line distribution is relatively uniform and the direction of the magnetic induction lines is relatively gentle.

[0082] The structure of this special-shaped heat pipe 2 is beneficial to reducing the use of refrigerant and improving the centripetal force burden caused by the high-speed rotation of the rotor core 1. Compared with a circular heat pipe, the gourd-shaped special-shaped heat pipe increases the effective contact area of the inner peripheral wall, especially increasing the curvature of the first arc. When using the same amount of refrigerant, the refrigerant deposited on the inner peripheral wall of the first arc region of the special-shaped heat pipe will have a larger inner peripheral wall contact area compared with a circular heat pipe with an equivalent radius of the special-shaped heat pipe. Therefore, less refrigerant use can achieve the same heat exchange effect, thereby reducing the use of refrigerant.

[0083] The structure of this special-shaped heat pipe 2 increases the contact area with the heat source and effectively improves the heat exchange efficiency. Compared with a circular pipe with an equivalent radius, this special-shaped heat pipe increases the arc length by combining the first, second, third, and fourth arc segments on the outer peripheral wall, and stretches a larger contact area axially. Since the second arc segment and the fourth arc segment are concave, this special-shaped heat pipe shape creates a larger contact area with a smaller cross-sectional area.

[0084] As described above, it is only the specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model can easily think of changes or substitutions, which should all be covered within the protection scope of the present utility model. Therefore, the protection scope of the present utility model shall be subject to the protection scope of the claimed rights.

[0085] Unless otherwise defined, the technical terms or scientific terms used in this disclosure shall have the ordinary meaning as understood by those of ordinary skill in the art to which this disclosure pertains. The "first", "second" and similar terms used in this disclosure do not denote any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "a", "an" or "the" do not denote a quantity limitation, but mean that there is at least one. The words such as "including" or "comprising" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "upper", "lower", "left", "right", etc. are only used to indicate the relative position relationship. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

Claims

1. A special-shaped heat pipe for improving heat dissipation of a permanent magnet rotor, characterized in that: The cross section of the outer peripheral wall of the special-shaped heat pipe (2) comprises a first arc segment (101), a second arc segment (102), a third arc segment (103) and a fourth arc segment (104) which are connected in sequence end to end, the center of the first arc segment (101) and the center of the third arc segment (103) are on a straight line, the radius of the first arc segment (101) is smaller than the radius of the third arc segment (103), and both ends of the second arc segment (102) are respectively adjacent to the first arc segment (104). The first end of the first circular arc segment (101) is tangent to the first end of the third circular arc segment (103), the two ends of the fourth circular arc segment (104) are tangent to the second end of the first circular arc segment (101) and the second end of the third circular arc segment (103), respectively, the centers of the first circular arc segment (101) and the third circular arc segment (103) are located on the inner side of the special-shaped heat pipe (2), and the centers of the second circular arc segment (102) and the fourth circular arc segment (104) are located on the outer side of the special-shaped heat pipe (2); The inner peripheral wall of the special-shaped heat pipe (2) is provided with a plurality of spaced-apart protruding tooth ridge structures (501), and tooth grooves (502) are formed between two adjacent tooth ridge structures (501); Along the length direction of the special-shaped heat pipe (2), the special-shaped heat pipe (2) comprises a first pipe section (100) and a second pipe section (200) which are connected to each other, and the first pipe section (100) and the second pipe section (200) are arranged at an angle.

2. The special-shaped heat pipe according to claim 1, characterized in that: A reference line is formed by a straight line where the center of the first circular arc segment (101) and the center of the third circular arc segment (103) are located, and the second circular arc segment (102) and the fourth circular arc segment (104) are symmetrically arranged relative to the reference line; The plane where the first pipe section (100) and the second pipe section (200) meet forms an interface (300), and the first pipe section (100) and the second pipe section (200) are symmetrically arranged relative to the interface (300).

3. The special-shaped heat pipe according to claim 2, characterized in that: The quadrant points of the third circular arc line segment (103) located on the reference line form reference points; The outer peripheral wall of the first pipe section (100) comprises a first straight line section (110) passing through a reference point; The outer peripheral wall of the second pipe section (200) includes a second straight line section (120) passing through a reference point; The first straight line segment (110) intersects with the second straight line segment (120), and an angle θ between the first straight line segment (110) and the second straight line segment (120) is greater than or equal to 175 degrees and less than 180 degrees.

4. The special-shaped heat pipe according to claim 2, characterized in that: Along the length direction of the special-shaped heat pipe (2), the multiple spaced-apart tooth ridge structures (501) on the inner peripheral wall of the first pipe section (100) and the multiple spaced-apart tooth ridge structures (501) on the inner peripheral wall of the second pipe section (200) both extend to the interface (300); The multiple tooth edge structures (501) on the inner circumferential wall of the first pipe section (100) and the multiple tooth edge structures (501) on the inner circumferential wall of the second pipe section (200) are symmetrically arranged relative to the interface (300).

5. The special-shaped heat pipe according to any one of claims 1 to 4, characterized in that: The special-shaped heat pipe (2) comprises a first enclosing plate (10) arranged in an annular shape, a second enclosing plate (20) arranged in an annular shape, a first end plate (30), a second end plate (40) and a partition plate (50); The second end of the first enclosure (10) is connected to the first end of the second enclosure (20), the first end plate (30) is connected to the first end of the first enclosure (10), the second end plate (40) is connected to the second end of the second enclosure (20), and the partition (50) is arranged at the junction of the first enclosure (10) and the second enclosure (20); The first pipe section (100) is formed by the first enclosure (10), the first end plate (30) and the partition (50); the second pipe section (200) is formed by the second enclosure (20), the second end plate (40) and the partition (50); the first pipe section (100) has a first enclosed space for filling a refrigerant; and the second pipe section (200) has a second enclosed space for filling a refrigerant.

6. The special-shaped heat pipe according to any one of claims 1 to 4, characterized in that: The radius of the first circular arc segment (101) is R; The radius of the third circular arc segment (103) is 2R; The radius of the second circular arc segment (102) and the radius of the fourth circular arc segment (104) are both 2R; The distance between the center of the first arc segment (101) and the center of the third arc segment (103) is 2.2R; Among them, R>0.

7. The special-shaped heat pipe according to any one of claims 1 to 4, characterized in that: The cross-sectional shape of the tooth edge structure (501) includes a first isosceles trapezoid (7) and a second isosceles trapezoid (8) connected to each other; the first isosceles trapezoid (7) is located on the side of the second isosceles trapezoid (8) close to the tooth root; the lower base of the first isosceles trapezoid (7) is close to the tooth root, the upper base of the first isosceles trapezoid (7) is connected to the lower base of the second isosceles trapezoid (8), and the upper base of the second isosceles trapezoid (8) is located on the side close to the tooth top; the length of the lower base of the first isosceles trapezoid (7) is greater than the length of the upper base of the first isosceles trapezoid (7), the length of the lower base of the second isosceles trapezoid (8) is greater than the length of the upper base of the second isosceles trapezoid (8), and the length of the upper base of the first isosceles trapezoid (7) is equal to the length of the lower base of the second isosceles trapezoid (8).

8. The special-shaped heat pipe according to claim 7, characterized in that: The cross-sectional shape of the tooth groove (502) comprises a first cross-sectional shape (111) and a second cross-sectional shape (112) connected to each other, the first cross-sectional shape (111) being arranged close to the groove bottom of the tooth groove (502), the first cross-sectional shape (111) being a structure that is wide at the top and narrow at the bottom, or a rectangular structure that is equal in width at the top and bottom, wherein the side close to the groove bottom of the tooth groove (502) is the bottom; The length of the lower base of the first isosceles trapezoid (7) is L1, and the length of the lower base of the second isosceles trapezoid (8) is L2, L1>L2; Wherein H is the height of the first isosceles trapezoid (7), and m is the number of tooth edges that the arc segment should have when it is a complete circle, reflecting the tooth edge density of the arc segment.

9. The special-shaped heat pipe according to any one of claims 1 to 4, characterized in that: The cross sections of the plurality of tooth ridge structures (501) form a plurality of tooth-shaped surfaces (6), and at least some of the plurality of tooth-shaped surfaces (6) meet the following requirements: A first vector is formed by pointing from the midpoint of the tooth bottom of the tooth profile surface (6) to the midpoint of the tooth top, and a second vector is formed by pointing from the center of the first circular arc segment (101) to the center of the third circular arc segment (103), and the angle between the first vector and the second vector is less than 90°.

10. A permanent magnet motor, characterized in that: The permanent magnet motor comprises: A rotor core (1), wherein the rotor core (1) is further provided with a plurality of mounting holes (11), each of the mounting holes (11) passes through two axial ends of the rotor core (1), and the plurality of mounting holes (11) are arranged at intervals around the circumference of the rotor core (1); A plurality of special-shaped heat pipes (2) for improving heat dissipation of a permanent magnet rotor, wherein the plurality of special-shaped heat pipes (2) are mounted in a one-to-one correspondence in the plurality of mounting holes (11), and the special-shaped heat pipes (2) for improving heat dissipation of a permanent magnet rotor are the special-shaped heat pipes (2) for improving heat dissipation of a permanent magnet rotor as claimed in any one of claims 1 to 9; each of the special-shaped heat pipes (2) is filled with a refrigerant; The shape of the mounting hole (11) is compatible with the shape of the special-shaped heat pipe (2), and the length of the special-shaped heat pipe (2) is greater than the length of the rotor core (1); after mounting, the third circular arc segment (103) of the special-shaped heat pipe (2) is closer to the axis of the rotor core (1) relative to the first circular arc segment (101), and the cross-section of each special-shaped heat pipe (2) is symmetrical along the radial line of the rotor core (1); both ends of each special-shaped heat pipe (2) extend to the outside of the rotor core (1), and the lengths extending to the outside of the rotor core (1) are equal.

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