Main shaft heat dissipation system and axial flux motor

Abstract

The utility model relates to the technical field of axial magnetic flux motors, in particular to a main shaft heat dissipation system and an axial magnetic flux motor, and aims to solve the problem of unstable operation caused by heat accumulation of a motor main shaft. The main shaft heat dissipation system provided by the utility model comprises a motor main shaft, a motor shell and a rotor unit, one side of the rotor unit is provided with a radial air channel, the other side of the rotor unit and the motor shell define a backflow air channel, and the outer circle of the rotor unit and the motor shell define a communication air channel. The motor main shaft is provided with a main shaft inner cavity, and an air return hole and an air outlet hole which are communicated with the main shaft inner cavity; the radial air channel, the communicating air channel, the backflow air channel, the air return hole, the inner cavity of the main shaft and the air outlet hole are sequentially communicated to form a circulating air channel. The rotor unit rotates to enable air in the radial air channel to generate centrifugal force and flow towards the communicating air channel, so that negative pressure is generated at the radial air channel to enable air in the inner cavity of the main shaft to flow along the circulating air channel, heat is prevented from being gathered on the main shaft of the motor, and stable operation of the motor is guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of axial flux motors, in particular to a spindle heat dissipation system and an axial flux motor. Background Art

[0002] In order to reduce the pulling force of the rotor magnet on the motor shaft, which causes the rotor back iron to be bent and deformed, a hollow shaft motor shaft design is used to increase the diameter of the motor shaft, thereby reducing the distance between the motor shaft and the magnet, reducing the force arm of the pulling force, and preventing the back iron from bending and deforming, affecting the motor air gap and making the rotor difficult to disassemble. However, due to the existence of hysteresis, eddy loss, and friction, heat is generated. The heat accumulates inside the hollow shaft, causing the temperature to rise abnormally, which will cause the motor shaft to expand and the matching between the shaft and the bearing to change, such as changes in bearing clearance and spindle roundness, resulting in abnormal noise, increased friction resistance, and unstable operation of the motor shaft, affecting the stable operation of the motor. Utility Model Content

[0003] The utility model aims to provide a spindle heat dissipation system and an axial flux motor to solve the problem of unstable operation caused by heat accumulation in the motor spindle.

[0004] In order to solve the above technical problems, the technical solution provided by the utility model is:

[0005] A spindle heat dissipation system comprises a motor spindle, a motor housing and a rotor unit;

[0006] The motor main shaft is rotatably mounted on the motor housing, and the rotor unit is sleeved on the motor main shaft and arranged in the motor housing;

[0007] The rotor unit is provided with a radial air passage on one side, and a return air passage is formed with the motor housing on the other side, and the outer circle of the rotor unit and the motor housing form a connecting air passage; the motor main shaft is provided with a main shaft inner cavity and a return air hole and an air outlet hole connected with the main shaft inner cavity;

[0008] The radial air passage, the connecting air passage, the return air passage, the return air hole, the main shaft inner cavity and the air outlet hole are sequentially connected to form a circulating air passage;

[0009] The rotor unit rotates around its own axis so that the airflow flows through the radial air passage, the connecting air passage, the return air passage, the return air hole, the main shaft cavity and the air outlet hole in sequence.

[0010] Furthermore, the rotor unit includes a plurality of permanent magnets evenly distributed around its axis, and the gaps between adjacent permanent magnets form the radial air passage.

[0011] Furthermore, the motor main shaft comprises an output shaft and a shaft sleeve, wherein the shaft sleeve is sleeved on the output shaft and forms a ring-shaped main shaft inner cavity with the output shaft;

[0012] The shaft sleeve is provided with the air outlet hole.

[0013] Furthermore, the motor main shaft also includes a shaft end cover, and two of the shaft end covers are sleeved on the output shaft and connected to the output shaft;

[0014] The two shaft end covers are inserted into the shaft sleeve and surround the shaft sleeve and the output shaft to form the main shaft inner cavity;

[0015] The shaft end cover is provided with the return air hole.

[0016] Furthermore, the rotor unit is connected to the shaft end cover and the shaft sleeve.

[0017] Furthermore, the rotor unit also includes a main back iron and a limit cover plate;

[0018] The permanent magnet is installed on the main back iron, and the limiting cover plate is provided with a limiting hole;

[0019] The permanent magnet is inserted into the limiting hole, and one end of the permanent magnet protruding from the limiting cover plate forms the radial air passage with the limiting cover plate.

[0020] Furthermore, the rotor unit further comprises a secondary back iron, wherein the secondary back iron is configured as an annular structure wound by a magnetic conductive plate, wherein the annular structure is radially divided into multiple layers, and insulating glue is filled between the layers;

[0021] The auxiliary back iron is arranged between the main back iron and the permanent magnet, one side of the auxiliary back iron is connected to the main back iron, and the other side of the auxiliary back iron is connected to the permanent magnet.

[0022] Furthermore, an annular mounting groove is provided on the main back iron, the auxiliary back iron and the permanent magnet are installed in the annular mounting groove, and the limiting cover plate is arranged on a side where the auxiliary back iron is connected to the permanent magnet.

[0023] Furthermore, the material of the magnetic conductive plate is nanocrystalline material or silicon steel material.

[0024] Another aspect of the present invention provides an axial flux motor, comprising the above-mentioned spindle heat dissipation system.

[0025] Based on the above technical solutions, the technical effects that can be achieved by the utility model are:

[0026] The spindle heat dissipation system provided by the utility model comprises a motor spindle, a motor housing and a rotor unit; the motor spindle is rotatably installed in the motor housing, and the rotor unit is sleeved on the motor spindle and arranged in the motor housing; a radial air duct is arranged on one side of the rotor unit, and a return air duct is formed with the motor housing on the other side, and a connecting air duct is formed with the outer circle of the rotor unit and the motor housing; a spindle inner cavity and a return air hole and an air outlet hole connected with the spindle inner cavity are arranged on the motor spindle; the radial air duct, the connecting air duct, the return air duct, the return air hole, the spindle inner cavity and the air outlet hole are connected in sequence to form a circulating air duct; the rotor unit rotates around its own axis so that the airflow flows through the radial air duct, the connecting air duct, the return air duct, the return air hole, the spindle inner cavity and the air outlet hole in sequence.

[0027] The spindle heat dissipation system provided by the utility model drives the radial airway to rotate by rotating the rotor unit around its own axis, so that the air in the radial airway generates centrifugal force and flows toward the connecting airway, that is, the air in the radial airway flows toward the outer cylindrical surface of the rotor unit, thereby generating negative pressure at the radial airway to make the gas in the inner cavity of the spindle flow to the radial airway through the air outlet, thereby forming a circulating air path driven by centrifugal force and negative pressure, so that the heat generated by the motor spindle is dispersed to the inside of the motor housing with the flowing air, thereby avoiding heat accumulation in the motor spindle, preventing excessive deformation of the motor spindle, etc., thereby avoiding abnormal noise, increased friction and the like during rotation, and ensuring the smooth operation of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A schematic diagram of the structure of the spindle heat dissipation system provided by an embodiment of the utility model;

[0030] Figure 2 for Figure 1 The enlarged view of point A in the middle;

[0031] Figure 3 A schematic diagram of the structure of an axial flux motor provided by an embodiment of the utility model;

[0032] Figure 4 It is a structural diagram of the motor spindle;

[0033] Figure 5 This is the main view of the motor shaft;

[0034] Figure 6 for Figure 5Middle BB section view;

[0035] Figure 7 is a schematic diagram of the structure of the rotor unit;

[0036] Figure 8 for Figure 7 Sectional view at point C in the middle;

[0037] Fig. 9 This is a schematic diagram of the structure of the main back iron;

[0038] Fig.10 is a front view of the electrode housing;

[0039] Fig.11 for Fig.10 Middle DD section view.

[0040] Icons: 100-motor main shaft; 200-motor housing; 300-rotor unit; 400-stator unit; 110-output shaft; 120-sleeve; 130-shaft end cover; 310-permanent magnet; 320-main back iron; 330-limiting cover plate; 340-auxiliary back iron; 311-annular mounting groove; 101-radial air duct; 102-connecting air duct; 103-return air duct; 104-return air hole; 105-spindle inner cavity; 106-air outlet hole. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0042] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In conjunction with the accompanying drawings, some embodiments of the present invention are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0044] The existing motor spindle will generate heat due to factors such as hysteresis, eddy loss and friction. The heat accumulates inside the motor spindle, causing the temperature to rise abnormally, which in turn causes the spindle to expand and changes in the fit between the spindle and the bearing, such as changes in bearing clearance and spindle roundness. This leads to abnormal noise when the motor spindle rotates, increased friction resistance, and unstable operation, affecting the stable operation of the motor.

[0045] In view of this, the utility model provides a spindle heat dissipation system, comprising a motor spindle 100, a motor housing 200 and a rotor unit 300; the motor spindle 100 is rotatably mounted on the motor housing 200, the rotor unit 300 is sleeved on the motor spindle 100 and arranged in the motor housing 200; a radial air passage 101 is arranged on one side of the rotor unit 300, and a return air passage 103 is formed with the motor housing 200 on the other side, and the outer circle of the rotor unit 300 and the motor housing 200 form a connecting air passage 102; The machine main shaft 100 is provided with a main shaft inner cavity 105 and a return air hole 104 and an air outlet hole 106 connected to the main shaft inner cavity 105; the radial air duct 101, the connecting air duct 102, the return air duct 103, the return air hole 104, the main shaft inner cavity 105 and the air outlet hole 106 are connected in sequence to form a circulating air duct; the rotor unit 300 rotates around its own axis so that the airflow flows through the radial air duct 101, the connecting air duct 102, the return air duct 103, the return air hole 104, the main shaft inner cavity 105 and the air outlet hole 106 in sequence.

[0046] The spindle heat dissipation system provided by the utility model drives the radial airway 101 to rotate by rotating the rotor unit 300 around its own axis, so that the air in the radial airway 101 generates centrifugal force and flows toward the connecting airway 102, that is, the air in the radial airway 101 flows toward the outer cylindrical surface of the rotor unit 300, thereby generating negative pressure at the radial airway 101 to make the gas in the spindle inner cavity 105 flow to the radial airway 101 through the air outlet 106, thereby forming a circulating air path driven by centrifugal force and negative pressure, so that the heat generated by the motor spindle 100 is dispersed into the inside of the motor housing 200 with the flowing air, thereby avoiding heat accumulation in the motor spindle 100, preventing the motor spindle 100 from excessive deformation, etc., thereby avoiding abnormal noise, increased friction and the like during rotation, and ensuring the smooth operation of the motor.

[0047] The following combination Figure 1-Figure 11 The structure and shape of the spindle cooling system provided in this embodiment are described in detail:

[0048] In this embodiment, the spindle heat dissipation system includes a motor spindle 100, a motor housing 200 and a rotor unit 300. Figure 1 As shown, the motor main shaft 100 is installed in the motor housing 200 through a bearing. A radial air passage 101 is provided on one side of the rotor unit 300. Figure 8As shown, the other side and the motor housing 200 form a return air duct 103, as shown in FIG. Figure 2 The outer circle of the rotor unit 300 and the motor housing 200 form a communicating air passage 102, as shown Figure 2 The motor spindle 100 is provided with a spindle inner cavity 105 and a return air hole 104 and an air outlet hole 106 communicating with the spindle inner cavity 105, as shown Figure 2 , Figure 4 shown.

[0049] The radial air passage 101, the connecting air passage 102, the return air passage 103, the return air hole 104, the spindle inner cavity 105 and the air outlet hole 106 are connected in sequence to form a circulating air passage; as the rotor unit 300 rotates around its own axis, the gas in the radial air passage 101 is driven to rotate with the rotor unit 300, thereby generating centrifugal force to make the gas in the radial air passage 101 flow toward the outer circle of the rotor unit 300, that is, flow toward the connecting air passage 102. At the same time, negative pressure is generated due to the outflow of gas in the radial air passage 101. Driven by the pressure difference generated by the negative pressure and the centrifugal force, the gas flows through the radial air passage 101, the connecting air passage 102, the return air passage 103, the return air hole 104, the spindle inner cavity 105 and the air outlet hole 106 in sequence to form an internal circulating flow, so that the heat is evenly distributed and heat accumulation is prevented.

[0050] In an optional solution of this embodiment, the motor main shaft 100 includes an output shaft 110, a sleeve 120 and a shaft end cover 130. Figure 4 , Figure 6 As shown. The shaft sleeve 120 is sleeved on the output shaft 110, and the two shaft end covers 130 are sleeved on the output shaft 110 and connected to the output shaft 110. The two shaft end covers 130 are inserted into the shaft sleeve 120 and form a ring-shaped main shaft inner cavity 105 with the shaft sleeve 120 and the output shaft 110. Among them, the shaft sleeve 120 is provided with air outlet holes 106 evenly distributed around its own axis, and the shaft end cover 130 is provided with return air holes 104 evenly distributed around its own axis. It should be noted that the main shaft inner cavity 105 can be set as a hole extending along the axis direction of the motor main shaft 100, and the two ends of the hole are respectively connected to the air outlet hole 106 and the return air hole 104.

[0051] In this embodiment, the rotor unit 300 includes a permanent magnet 310, a main back iron 320, a limit cover plate 330 and a secondary back iron 340. Figure 2 , Figure 8 The main back iron 320 is provided with an annular mounting groove 311, as shown in FIG. Fig. 9As shown, the secondary back iron 340 and the permanent magnet 310 are both installed in the annular installation groove 311, and the secondary back iron 340 is arranged between the main back iron 320 and the permanent magnet 310, one side is connected to the main back iron 320, and the other side is connected to the permanent magnet 310. A plurality of permanent magnets 310 are evenly distributed around the axis of the main back iron 320, and the limiting cover plate 330 is arranged on the side where the secondary back iron 340 is connected to the permanent magnet 310. A limiting hole is provided on the limiting cover plate 330, and the permanent magnet 310 is inserted into the limiting hole to ensure that the position is fixed. One end of the permanent magnet 310 protruding from the limiting cover plate 330 and the limiting cover plate 330 form a radial airway 101, that is, a radial airway 101 is formed between adjacent permanent magnets 310 and the limiting cover plate 330.

[0052] In this embodiment, the secondary back iron 340 is configured as an annular structure wound by a magnetic conductive plate, and the annular structure is divided into multiple layers along the radial direction, and insulating glue is filled between the layers. The magnetic conductive plate is made of a material with ultra-high magnetic permeability, and silicon steel material or nanocrystalline material can be selected, so as to ensure that the secondary back iron 340 has good magnetic conductivity and suppresses the generation of eddy currents; the insulating glue is a two-component epoxy resin glue.

[0053] The rotor unit 300 provided in this embodiment ensures the supporting strength through the main back iron 320, adopts the auxiliary back iron 340 formed by multi-layer winding to conduct magnetism to the permanent magnet 310, and reduces eddy current loss and harmonic loss through its multi-layer structure, thereby significantly reducing the heat generation of the permanent magnet 310 and avoiding high motor loss and demagnetization of the permanent magnet 310.

[0054] Specifically, the secondary back iron 340 is in the shape of a spiral line, and the same shape includes a coil spring, a disc mosquito coil, etc. The insulation between the layers and the fixation of the annular structure of the secondary back iron 340 are achieved by insulating glue, so as to achieve a compact sheet structure to reduce eddy current loss and harmonic loss by reducing thickness, and at the same time, the resistance value can be increased to reduce the induced current.

[0055] In this embodiment, the main back iron 320 can be made of steel, such as 45# steel, so as to obtain good processing accuracy and support strength, and prevent bending deformation caused by the pull of the rotor on the permanent magnet 310. The combination of the main back iron 320 and the auxiliary back iron 340 not only ensures the support strength of the rotor unit 300, but also effectively suppresses the generation of eddy currents.

[0056] In this embodiment, the limiting cover plate 330 is made of non-metallic materials such as glass fiber board, carbon fiber reinforced plastic, glass fiber reinforced plastic, glass fiber reinforced PEEK, etc., to ensure the limiting strength of the permanent magnet 310 and avoid the generation of induced current. Figure 8 As shown, arcs are arranged at the four corners of the limiting hole, and the sharp corners are removed by milling the circular hole, so as to facilitate the installation of the permanent magnet 310 .

[0057] In the optional scheme of this embodiment, the permanent magnet 310 is divided into multiple layers along the radial direction of the auxiliary back iron 340, and insulating glue is filled between the layers. The permanent magnet 310 made of a multi-layer structure can reduce eddy current loss and harmonic loss. The insulating glue can also use a two-component epoxy resin glue to achieve bonding and insulation between layers. Preferably, the number of layers of the permanent magnet 310 is the same as the number of layers of the auxiliary back iron 340 and corresponds one to one, so as to avoid the situation where the two are mutually conductive and the insulating layer loses its function. That is, it is avoided that two adjacent layers of the auxiliary back iron 340 are connected to one layer of the permanent magnet 310 at the same time, thereby causing the two adjacent layers of the auxiliary back iron 340 to be conductive.

[0058] In the optional solution of this embodiment, the permanent magnet 310 is made of rare earth permanent magnet material. Since the rare earth permanent magnet material has low internal resistance, significant eddy current loss will be generated when the motor is running. The multi-layer permanent magnet 310 composed of dozens of permanent magnet sheets bonded by insulating adhesive can block the formation of eddy current to reduce loss and reduce the temperature of the permanent magnet 310 to avoid high temperature demagnetization.

[0059] In the optional scheme of this embodiment, the permanent magnet 310 can be set to a fan shape or a trapezoidal shape, and the shape can be adjusted to increase the speed of the motor when it resonates, prevent the motor from shaking and resonant whistling noise in the working state, and keep the motor running stably. In this embodiment, by designing the shape of the permanent magnet 310, the speed of the motor resonating is above 2000 rpm, while the motor usually rotates below 1500 rpm. The various losses of the rotor unit 300 of this embodiment are reduced to a negligible level, making the motor more energy-efficient and efficient, with a power saving rate of up to 30%-80%.

[0060] In this embodiment, the main back iron 320 is connected to the shaft end cover 130 and the shaft sleeve 120 by screws to achieve the connection between the rotor unit 300 and the motor main shaft 100, and the distance between the two rotor units 300 is controlled.

[0061] Based on the spindle heat dissipation system provided in this embodiment, an axial flux motor is proposed, including the above-mentioned spindle heat dissipation system, and also including a stator unit 400, the stator unit 400 is installed in the motor housing 200 and is coaxially arranged with the rotor unit 300, and the two rotor units 300 are arranged on both sides of the stator unit 400. The air gap formed by the stator unit 400 and the rotor unit 300 ensures that the negative pressure generated by the radial airway 101 can effectively drive the air out of the spindle inner cavity 105, so that the gas circulation is smooth and fully flows through each part, ensuring the speed of gas circulation, thereby achieving effective heat dispersion, and preventing the heat of the motor spindle 100 from being taken away in time. At the same time, the stator unit 400 enables the axial flux motor to form two relatively independent circulation airways.

[0062] The existing axial flux motors are designed for extremely low power, because the motor diameter will increase with the increase of power, and the rotor diameter will also increase accordingly, which will cause the outer circle of the motor shaft to be at a greater distance from the inner circle formed by the permanent magnet 310, and the distance from the axis of the rotor to the permanent magnet 310 will increase. This situation will cause the permanent magnet 310 to be easily attracted to the stator core when assembling the motor, causing the back iron of the rotor to be partially bent and deformed and difficult to disassemble. Even if it is barely assembled, the air gap of the motor needs to be set larger. In this embodiment, the motor main shaft 100 is formed into a hollow shaft by setting the shaft sleeve 120 and the diameter of the motor main shaft 100 where the rotor unit 300 is installed is increased, shortening the distance from the permanent magnet 310 to the surface of the motor main shaft 100, thereby reducing the force arm when the permanent magnet 310 is subjected to the pulling force of the stator unit 400, and avoiding the main back iron 320 from bending and deforming due to excessive bending moment. This structure ensures that both ends of the motor main shaft 100 are supported by small diameter bearings, shortens the force arm of the stator core's pulling force to attract the permanent magnet 310, avoids bending and deformation of the main back iron 320 causing damage to the motor, and avoids the problem of simply increasing the back iron thickness, which increases the moment of inertia of the rotor unit 300 and reduces the motor efficiency.

[0063] In short, the hollow stepped shaft of this embodiment not only shortens the distance between the permanent magnet 310 and the outer circle of the motor main shaft 100 through the support of the rotor unit 300 by the large-diameter sleeve 120, shortens the tensile force arm of the permanent magnet 310, avoids resisting the bending moment by increasing the thickness of the main back iron 320, ensures the strength of the rotor unit 300 and avoids the increase of the moment of inertia; and reduces the moment of inertia of the motor through the hollow shaft design, so that the axial flux motor achieves high power. That is, the design of the hollow shaft not only ensures the strength of the motor main shaft 100, but also helps to reduce the moment of inertia and the heat dissipation of the axis.

[0064] In the optional solution of this embodiment, the motor main shaft 100 can be made of a hollow shaft made of an alloy with good fatigue resistance, and two thin hollow shafts are riveted and welded at both ends of the hollow shaft. That is, three sections of hollow shafts are welded, and the middle section is a large diameter section. The alloy can be made of titanium alloy, aluminum alloy and other materials.

[0065] Since the permanent magnet 310 is close to the outer circle of the motor main shaft 100, the lever arm is reduced, and the axial flux motor provided in this embodiment will not have the main back iron 320 bending, causing the permanent magnet 310 to be attracted to the stator iron core and difficult to separate. Therefore, the air gap can be designed to be smaller to improve the efficiency of the motor, and the main back iron 320 bending will not cause the stator unit 400 and the rotor unit 300 to be attracted together, ensuring the normal operation of the high-power axial flux motor.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. A spindle cooling system, characterized in that: It comprises a motor main shaft (100), a motor housing (200) and a rotor unit (300); The motor main shaft (100) is rotatably mounted on the motor housing (200), and the rotor unit (300) is sleeved on the motor main shaft (100) and arranged in the motor housing (200); The rotor unit (300) is provided with a radial air passage (101) on one side, and forms a return air passage (103) with the motor housing (200) on the other side; the outer circle of the rotor unit (300) and the motor housing (200) form a communicating air passage (102); the motor main shaft (100) is provided with a main shaft inner cavity (105) and a return air hole (104) and an air outlet hole (106) communicating with the main shaft inner cavity (105); The radial air passage (101), the connecting air passage (102), the return air passage (103), the return air hole (104), the main shaft inner cavity (105) and the air outlet hole (106) are sequentially connected to form a circulating air passage; The rotor unit (300) rotates around its own axis so that the airflow flows sequentially through the radial air channel (101), the connecting air channel (102), the return air channel (103), the return air hole (104), the main shaft inner cavity (105) and the air outlet hole (106).

2. The spindle cooling system according to claim 1, characterized in that: The rotor unit (300) comprises a plurality of permanent magnets (310) evenly distributed around its axis, and the gaps between adjacent permanent magnets (310) form the radial air channel (101).

3. The spindle cooling system according to claim 1, characterized in that: The motor main shaft (100) comprises an output shaft (110) and a shaft sleeve (120), wherein the shaft sleeve (120) is sleeved on the output shaft (110) and forms a ring-shaped main shaft inner cavity (105) with the output shaft (110); The shaft sleeve (120) is provided with the air outlet hole (106).

4. The spindle cooling system according to claim 3, characterized in that: The motor main shaft (100) further comprises a shaft end cover (130), wherein two shaft end covers (130) are sleeved on the output shaft (110) and connected to the output shaft (110); The two shaft end covers (130) are inserted into the shaft sleeve (120) and together with the shaft sleeve (120) and the output shaft (110) form the main shaft inner cavity (105); The shaft end cover (130) is provided with the return air hole (104).

5. The spindle cooling system according to claim 4, characterized in that: The rotor unit (300) is connected to the shaft end cover (130) and the shaft sleeve (120).

6. The spindle cooling system according to claim 2, characterized in that: The rotor unit (300) further comprises a main back iron (320) and a limiting cover plate (330); The permanent magnet (310) is mounted on the main back iron (320), and a limiting hole is provided on the limiting cover plate (330); The permanent magnet (310) is inserted into the limiting hole, and one end of the permanent magnet (310) protruding from the limiting cover plate (330) and the limiting cover plate (330) form the radial airway (101).

7. The spindle cooling system according to claim 6, characterized in that: The rotor unit (300) further comprises a secondary back iron (340), wherein the secondary back iron (340) is configured as an annular structure wound by a magnetic conductive plate, wherein the annular structure is divided into multiple layers along the radial direction, and insulating glue is filled between the layers; The auxiliary back iron (340) is arranged between the main back iron (320) and the permanent magnet (310), with one side connected to the main back iron (320) and the other side connected to the permanent magnet (310).

8. The spindle cooling system according to claim 7, characterized in that: The main back iron (320) is provided with an annular mounting groove (311), the auxiliary back iron (340) and the permanent magnet (310) are mounted in the annular mounting groove (311), and the limiting cover plate (330) is arranged on a side where the auxiliary back iron (340) and the permanent magnet (310) are connected.

9. The spindle cooling system according to claim 8, characterized in that: The material of the magnetic conductive plate is nanocrystalline material or silicon steel material.

10. An axial flux motor, characterized in that: It comprises a spindle cooling system as described in any one of claims 1 to 9.

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