A permanent magnet motor

Abstract

The application discloses a permanent magnet motor, which comprises a base, a stator, a rotor, a rotating shaft and an airflow driving assembly. The base is internally formed with a first end space and a second end space on the two sides of the rotor in the axial direction. The rotor is provided with a first rotor air duct which is communicated with the two end spaces. The base is provided with heat exchange cavities which are communicated with the two end spaces respectively. The first end space, the first rotor air duct, the second end space and the heat exchange cavities are communicated in sequence to form an internal circulation air path. The base is further provided with a cooling flow channel which is in heat conduction connection with the heat exchange cavities. The airflow driving assembly drives the air to circulate along the internal circulation air path, so that the heat carried by the air is transmitted to the cooling medium in the cooling flow channel and is taken away. The external air is reduced to enter the motor, and the risk of ferromagnetic particles and dust entering the air gap of the stator and the rotor is reduced.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a permanent magnet motor. Background Technology

[0002] As rail transit equipment develops towards higher efficiency and lighter weight, permanent magnet motors, with their high operating efficiency and power density, are increasingly being used in the traction systems of locomotives, EMUs, and urban rail vehicles. Traction motors need to operate continuously over a wide torque and speed range. When the stator windings are energized, copper losses are generated; the alternating magnetic field in the stator and rotor generates iron losses; and frictional heat is generated in bearings, seals, and gear transmission components. If this heat cannot be dissipated in time, the temperature of the stator windings, rotor, permanent magnets, and bearings will rise, thus affecting the continuous and reliable operation of the motor.

[0003] Most high-power locomotive traction motors currently use forced-air cooling asynchronous motors. These motors use a fan to draw in outside air, which then flows through the stator winding ends, the rotor, and the air gap between the stator and rotor before being exhausted, thus carrying away the heat generated inside the motor. While this cooling method has a relatively direct air path, it also allows outside air to enter the motor.

[0004] The operating environment of rail vehicles contains foreign objects such as iron filings, metal powder, brake shavings, and dust. When the aforementioned forced air cooling method is applied to permanent magnet motors, ferromagnetic particles that enter the motor with the external air are easily gathered on the rotor surface and in the air gap between the stator and rotor under the influence of the permanent magnet rotor's magnetic field. This may cause friction between the stator and rotor or damage the insulation of the stator windings, affecting the operational safety of the permanent magnet motor. Summary of the Invention

[0005] In view of the above, it is necessary to provide a permanent magnet motor to improve the problem that existing forced air-cooled traction motors require external air to be sent into the motor, which may cause ferromagnetic particles and dust to enter the air gap between the stator and rotor, thereby causing friction between the stator and rotor or damage to the winding insulation.

[0006] To achieve the above objectives, the present invention provides a permanent magnet motor, comprising a frame, a stator, a rotor, a shaft, and an airflow drive assembly. The stator is fixed within the frame, and the rotor is located radially inside the stator and fixedly sleeved on the shaft. A first end space and a second end space are formed on both axial sides of the rotor within the frame. The rotor has a first rotor air duct extending axially, with its two ends communicating with the first end space and the second end space, respectively. The frame has a heat exchange chamber, with its two ends communicating with the first end space and the second end space, respectively, so that the first end space, the first rotor air duct, the second end space, and the heat exchange chamber are connected end-to-end to form an internal circulation air path. The frame also has a cooling channel for the flow of cooling medium, which is thermally connected to the heat exchange chamber, allowing the cooling medium to absorb the heat carried by the air flowing through the heat exchange chamber. The airflow drive assembly is connected to the shaft and is used to drive the air within the frame to circulate along the internal circulation air path.

[0007] In some embodiments, the base includes an inner cylinder and an outer cylinder sleeved around the outer periphery of the inner cylinder, and a stator is fixed to the inner periphery of the inner cylinder. Cooling channels are formed between the outer periphery of the inner cylinder and the inner periphery of the outer cylinder, and the base is provided with a cooling medium inlet and a cooling medium outlet respectively communicating with the cooling channels. The heat exchange chamber is located radially outside the outer cylinder, such that the cooling channels are located between the stator and the heat exchange chamber.

[0008] In some embodiments, the cooling channel has a first sidewall and a second sidewall disposed opposite to each other along the axial direction of the rotor. A plurality of guide vanes are provided within the cooling channel, spaced apart circumferentially along the inner cylinder. The radial inner edge and radial outer edge of each guide vane are connected to the inner cylinder and the outer cylinder, respectively. In two adjacent guide vanes, one extends from the first sidewall toward the second sidewall, and the other extends from the second sidewall toward the first sidewall. A flow gap is formed between the free end of each guide vane and the sidewall it faces, thereby creating a cooling medium flow path within the cooling channel that extends circumferentially and reciprocates axially.

[0009] In some embodiments, the outer periphery of the outer cylinder is provided with a plurality of ventilation ribs spaced apart along the circumference of the outer cylinder, each ventilation rib extending along the axial direction of the rotor. Each ventilation rib is spaced apart from the outer circumferential surface of the outer cylinder and together with the outer circumferential surface of the outer cylinder to form a heat exchange cavity. The plurality of heat exchange cavities are distributed at intervals along the circumference of the outer cylinder, and the two ends of each heat exchange cavity are respectively connected to a first end space and a second end space.

[0010] In some embodiments, each heat exchange chamber is provided with a radiator. The radiator includes a heat-conducting substrate and a plurality of heat-dissipating fins disposed on the heat-conducting substrate. The heat-conducting substrate is fixed to the outer peripheral surface of the outer cylinder, and the plurality of heat-dissipating fins are located on the side of the heat-conducting substrate away from the outer cylinder and extend from the heat-conducting substrate toward the corresponding ventilation ribs. A heat-conducting material layer is provided between the heat-conducting substrate and the outer peripheral surface of the outer cylinder, and the cylinder wall in the outer cylinder located between the heat-conducting substrate and the cooling channel is in thermal contact with the heat-conducting substrate and the cooling medium, respectively.

[0011] In some embodiments, the outer periphery of the outer cylinder is further provided with a plurality of pull plates, each pull plate extending along the axial direction of the rotor, and its two axial ends being fixedly connected to the two axial ends of the base, respectively. The plurality of pull plates and the plurality of ventilation ribs are alternately arranged along the circumference of the outer cylinder.

[0012] In some embodiments, the airflow drive assembly includes at least one rotating member connected to a rotating shaft, and an inner circulation blade portion disposed on the at least one rotating member. The inner circulation blade portion includes a plurality of inner circulation blades spaced circumferentially along the corresponding rotating member, and the plurality of inner circulation blades are at least partially located within one of a first end space and a second end space.

[0013] In some embodiments, a first pressure ring and a second pressure ring are fixed to both ends of the rotor along its axial direction. The first pressure ring has a plurality of first guide holes connecting the first end space and the first rotor air duct, and the second pressure ring has a plurality of second guide holes connecting the second end space and the first rotor air duct. Both the first and second guide holes are inclined relative to the rotor's axial direction, and the axes of the first and second guide holes extend toward the ends of adjacent stator windings, respectively.

[0014] In some embodiments, the rotor further includes a second rotor duct extending axially and isolated from the first rotor duct. A first external ventilation space and a second external ventilation space are formed at both axial ends of the rotor within the frame. The first external ventilation space and the first end space are located at the same axial end of the rotor and are isolated from each other. The second external ventilation space and the second end space are located at the other axial end of the rotor and are isolated from each other. The two ends of the second rotor duct communicate with the first and second external ventilation spaces, respectively. The first and second external ventilation spaces are connected to the outside via the first and second external ventilation ducts on both sides of the frame's axial direction, forming an external ventilation path isolated from the internal circulation airflow path. The airflow drive assembly also includes an external ventilation blade portion disposed on at least one rotating member. The external ventilation blade portion includes a plurality of external ventilation blades spaced circumferentially along the corresponding rotating member, and the plurality of external ventilation blades are at least partially located within one of the first and second external ventilation spaces.

[0015] In some embodiments, the permanent magnet motor further includes a gearbox, a coupling, gears, and an oil return ring. The gearbox is connected to the drive end of the base, the coupling is fixedly sleeved on the drive end of the rotating shaft, and the gear is disposed within the gearbox and connected to the coupling. The oil return ring is disposed within the gearbox and surrounds the coupling, with an oil return gap formed between the inner circumferential surface of the oil return ring and the outer circumferential surface of the coupling. The inner circumferential surface of the oil return ring has multiple circumferentially extending and axially spaced oil collecting grooves and a confluence groove communicating with the multiple oil collecting grooves. The gearbox wall has an oil return hole, one end of which communicates with the confluence groove, and the other end of which communicates with the oil chamber of the gearbox. A pressure balance channel is also provided between the oil return ring and the gearbox wall, one end of which communicates with the end of the oil return gap near the rotor, and the other end of which communicates with the outside and is isolated from the internal circulation air path.

[0016] Compared with the aforementioned background technology, the permanent magnet motor provided by the present invention has at least the following advantages: Existing forced-air-cooled traction motors remove heat generated during operation by introducing external air into the motor, allowing it to flow through the stator, rotor, and the air gap between them before being discharged. Ferromagnetic particles and dust from the rail vehicle's operating environment may enter the motor along with the external air. These ferromagnetic particles may also accumulate on the rotor surface and in the air gap between the stator and rotor under the influence of the permanent magnet rotor's magnetic field, potentially causing friction between the stator and rotor or damaging the insulation of the stator windings.

[0017] In this invention, the two ends of the first rotor duct are respectively connected to the first end space and the second end space, and the two ends of the heat exchange cavity are also respectively connected to the first end space and the second end space, thereby connecting the first end space, the first rotor duct, the second end space, and the heat exchange cavity end to end to form an internal circulation air path. The airflow drive assembly is connected to the rotating shaft. When the airflow drive assembly moves with the rotating shaft, it drives the air in the frame to circulate along the internal circulation air path. When the air passes through the first end space and the second end space, it can exchange heat with the stator winding ends and the axial ends of the rotor. When the air passes through the first rotor duct, it can exchange heat with the rotor, thereby absorbing some of the heat generated by the stator winding ends and the rotor.

[0018] After the air carrying heat enters the heat exchange chamber, the heat in the air can be transferred from the heat exchange chamber to the cooling channel connected to it. The cooling medium flows in the cooling channel and absorbs the heat transferred from the heat exchange chamber, and then carries this heat away from the base. The air, now cooled, continues to enter the first end space or the second end space, and passes through the first rotor air duct and the heat exchange chamber again, thus repeating the heat absorption and release process.

[0019] With the above configuration, the air inside the motor frame can circulate repeatedly between the first end space, the first rotor duct, the second end space, and the heat exchange chamber. The absorbed heat is carried out of the motor by the cooling medium in the cooling channels, thus reducing the need to continuously supply external air into the first rotor duct and both end spaces. This reduces the likelihood of ferromagnetic particles and dust entering the motor with the cooling air, lowering the risk of these particles and dust entering the air gap between the stator and rotor. Attached Figure Description

[0020] To more clearly illustrate the technical content of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention, and those skilled in the art can obtain other drawings based on the provided drawings without creative effort.

[0021] Figure 1 This is an axial cross-sectional view of the permanent magnet motor provided in an embodiment of the present invention; Figure 2 This is an axial cross-sectional schematic diagram of a permanent magnet motor provided in another embodiment of the present invention; Figure 3 This is a schematic diagram of the radial cross-section of the base provided in an embodiment of the present invention; Figure 4 for Figure 2 An enlarged schematic diagram of the cooling channel section; Figure 5 This is a schematic diagram of the cooling channel provided in an embodiment of the present invention after it is expanded along the circumference of the inner cylinder. Figure 6 This is a schematic diagram of the airflow drive assembly provided in an embodiment of the present invention; Figure 7 for Figure 2 An enlarged schematic diagram of the gearbox and oil return ring section; Figure 8 This is an axial cross-sectional view of a forced air-cooled traction motor in the prior art.

[0022] Explanation of reference numerals in the attached figures: 10. Base; 11. Inner cylinder; 12. Outer cylinder; 13. Cooling channel; 131. First side wall; 132. Second side wall; 133. Guide vane; 14. Heat exchange chamber; 15. Ventilation rib; 16. Pull plate; 17. Radiator; 18. Thermal conductive material layer; 20. Stator; 21. Stator winding; 30. Rotor; 31. First rotor air duct; 32. Second rotor air duct; 40. Shaft; 50. First end space; 60. Second end space; 71. First rotating component; 72. Internal circulation blade section; 73. External ventilation blade section; 74. Second rotating component; 81. First external ventilation space; 82. Second external ventilation space; 90. Gearbox; 91. Coupling; 92. Gear; 93. Oil return ring; 931. Oil collection groove; 932. Combustion groove; 94. Oil return hole; 95. Air pressure balance channel. Detailed Implementation

[0023] Please refer to the following: Figures 1 to 8 This specific embodiment provides a permanent magnet motor, which can be applied to the traction system of rail vehicles such as locomotives, EMUs, or urban rail vehicles. For ease of description, the end of the permanent magnet motor connected to the gearbox 90 is referred to as the transmission end, and the end of the shaft 40 away from the gearbox 90 is referred to as the non-transmission end. In this embodiment, the first end space 50 and the first external ventilation space 81 are located on the transmission end side, and the second end space 60 and the second external ventilation space 82 are located on the non-transmission end side. It should be noted that the above division between the transmission end and the non-transmission end, as well as the flow direction indicated by the airflow arrows in the accompanying drawings, are merely exemplary descriptions made for the convenience of understanding this embodiment. The first end space 50 and the second end space 60 can also correspond to the non-transmission end and the transmission end, respectively, and this embodiment is not limited thereto.

[0024] like Figure 1 As shown, the permanent magnet motor mainly includes a frame 10, a stator 20, a rotor 30, a shaft 40, and an airflow drive assembly. The stator 20 is fixed inside the frame 10, and the rotor 30 is located radially inside the stator 20 with an air gap between them. The rotor 30 is fixedly sleeved on the shaft 40, which is rotatably supported on the frame 10. Permanent magnets are arranged circumferentially on the rotor 30, and a stator winding 21 is wound on the stator 20. The energized stator winding 21 interacts with the permanent magnets of the rotor 30 to drive the rotor 30 and the shaft 40 to rotate. In this embodiment, the permanent magnet motor and the gearbox 90 are integrated. The transmission end of the shaft 40 shares a support portion located at the transmission end with the gearbox 90, thus eliminating the separate motor end cover and support bearing at the transmission end, and only providing a support bearing at the non-transmission end. This design shortens the axial dimension and reduces the weight of the entire drive unit, making it suitable for both standard gauge and narrow gauge applications. Furthermore, the advantages of permanent magnet motors over asynchronous motors in terms of efficiency and torque output further enhance the power density of the entire drive unit.

[0025] like Figure 3 and Figure 4As shown, the base 10 includes an inner cylinder 11 and an outer cylinder 12 sleeved around the outer periphery of the inner cylinder 11. The stator 20 is fixed to the inner periphery of the inner cylinder 11, and the heat generated by the stator 20 during operation can be conducted radially outward through the inner cylinder 11. A circumferentially extending cooling channel 13 is formed between the outer periphery of the inner cylinder 11 and the inner periphery of the outer cylinder 12. The base 10 also has a cooling medium inlet and a cooling medium outlet (not shown in the figure) respectively communicating with the cooling medium outlet 13. The cooling medium enters the cooling medium outlet 13 through the cooling medium outlet, flows radially outward along the stator 20, and is discharged through the cooling medium outlet, thereby carrying away the heat transferred from the stator 20 through the inner cylinder 11. In this embodiment, the cooling medium is preferably water. In other embodiments, the cooling medium may also be an aqueous solution of ethylene glycol, cooling oil, or other fluids that can meet the cooling requirements of the motor.

[0026] In particular, such as Figure 1 and Figure 3 As shown, the heat exchange chamber 14 is located radially outside the outer cylinder 12, thus placing the cooling channel 13 radially between the stator 20 and the heat exchange chamber 14. Consequently, the radially inner side of the cooling channel 13 receives heat from the stator 20 via the inner cylinder 11, while the radially outer side of the cooling channel 13 receives heat from the air inside the heat exchange chamber 14 via the outer cylinder 12. The cooling medium can simultaneously absorb heat from both the radially inner and outer sides. Compared to a scheme where the water channel is arranged on the outermost side and the internal circulating air is arranged on the inner side, the arrangement in this embodiment shortens the heat transfer path between the internal circulating air and the cooling medium, improves the heat exchange efficiency of the cooling medium, and avoids the problems of reducing the motor's ferromagnetic material and weakening torque output caused by opening internal circulating air channels on the stator core.

[0027] To further improve the heat exchange effect of the cooling medium in the cooling channel 13, such as Figure 4 and Figure 5As shown, the cooling channel 13 has a first sidewall 131 and a second sidewall 132 arranged opposite to each other along the axial direction of the rotor 30. Multiple guide vanes 133 are provided within the cooling channel 13, spaced apart circumferentially along the inner cylinder 11. The radial inner edge and radial outer edge of each guide vane 133 are connected to the inner cylinder 11 and the outer cylinder 12, respectively, to restrict the bypass of the cooling medium from the radial inner and outer sides of the guide vane 133. In two adjacent guide vanes 133, one extends from the first sidewall 131 toward the second sidewall 132, and the other extends from the second sidewall 132 toward the first sidewall 131, with a flow gap formed between the free end of each guide vane 133 and the sidewall it faces. Thus, the cooling medium advances circumferentially between adjacent guide vanes 133 and axially reciprocates as it passes through each flow gap, forming a tortuous cooling medium flow path within the cooling channel 13 that extends circumferentially and axially reciprocates. This tortuous flow path reduces the short-circuit direct flow of the cooling medium from the cooling medium inlet to the cooling medium outlet, and extends the contact path and contact time between the cooling medium and the cylinder wall of the base 10, allowing the cooling medium to flow sequentially through the radially opposite areas of each heat exchange chamber 14, thereby improving the uniformity and sufficiency of heat exchange.

[0028] In some embodiments, the guide vanes 133 are not limited to straight strips; they can also be arc-shaped strips or strips with locally widened portions to adjust local flow rates and heat transfer intensity. Adjacent flow gaps can be located on different axial sides of the cooling channel 13, or they can partially overlap in the axial position. Furthermore, the aforementioned staggered guide vanes 133 can also be replaced by an integrally formed continuous tortuous baffle, as long as the continuous tortuous baffle can define a cooling medium flow path that extends circumferentially and reciprocates axially within the cooling channel 13. The guide vanes 133 can be integrally formed with the inner cylinder 11, integrally formed with the outer cylinder 12, or can be connected as independent components between the inner cylinder 11 and the outer cylinder 12.

[0029] Please continue reading. Figure 3 and Figure 4 The outer cylinder 12 is provided with a plurality of ventilation ribs 15 spaced apart along the circumference of the outer cylinder 12. Each ventilation rib 15 extends axially along the rotor 30 and is spaced apart from the outer circumferential surface of the outer cylinder 12, thereby enclosing a heat exchange cavity 14 with the outer circumferential surface of the outer cylinder 12. The plurality of ventilation ribs 15 are distributed circumferentially, and correspondingly a plurality of heat exchange cavities 14 are formed on the outer circumference of the base 10. The two axial ends of each heat exchange cavity 14 are respectively connected to the first end space 50 and the second end space 60, so that the internal circulating air can transfer heat to the cooling medium at multiple positions around the base 10. In this embodiment, the number of ventilation ribs 15 and heat exchange cavities 14 is preferably three, but not limited thereto. The number can be adjusted to two, four or more according to the diameter of the base 10, the required flow area and the load-bearing requirements.

[0030] Furthermore, a first guide cavity and a second guide cavity are also formed within the base 10. The first guide cavity is located between the second end space 60 and the heat exchange cavity 14, with one end connected to the second end space 60 and the other end connected to the heat exchange cavity 14. The second guide cavity is located between the heat exchange cavity 14 and the first end space 50, with one end connected to the heat exchange cavity 14 and the other end connected to the first end space 50. Thus, the first end space 50, the first rotor air duct 31, the second end space 60, the first guide cavity, the heat exchange cavity 14, and the second guide cavity are sequentially connected to form an internal circulation air path for air circulation within the base 10. For the multiple heat exchange cavities 14 spaced apart along the circumference of the base 10, each heat exchange cavity 14 can be connected to the second end space 60 and the first end space 50 respectively via the corresponding first guide cavity and second guide cavity.

[0031] like Figure 1 As shown, the second guide cavity extends obliquely relative to the axial direction of the rotating shaft 40, and the extension line of the central axis of the second guide cavity passes through the region where the stator winding 21 is located. In the airflow state shown, air transfers heat to the radiator 17 within the heat exchange cavity 14, and then to the cooling medium in the cooling channel 13 via the radiator 17 and outer cylinder 12. The cooled air enters the first end space 50 through the second guide cavity and flows towards the end of the stator winding 21 under the guidance of the second guide cavity, allowing the air to flow directly through the end of the stator winding 21 after exiting the second guide cavity. The oblique extension direction of the second guide cavity also causes the air to gradually change its flow direction when entering the first end space 50 from the heat exchange cavity 14, reducing flow separation, local eddies, and pressure loss caused by sudden air changes, which helps to reduce flow resistance at this location. The first guide cavity can also extend obliquely relative to the axial direction of the rotating shaft 40, allowing the air in the second end space 60 to enter the heat exchange cavity 14 more smoothly.

[0032] The outer cylinder 12 is also provided with multiple pull plates 16 on its outer periphery. Each pull plate 16 extends axially along the rotor 30, and its two axial ends are fixedly connected to the two axial ends of the base 10, for example, by welding to the end structures at both ends of the base 10. The multiple pull plates 16 and multiple ventilation ribs 15 are alternately arranged along the circumference of the outer cylinder 12. The pull plates 16 are used to bear the impact loads transmitted to the base 10 through the suspension parts under the suspension methods such as frame suspension and axle-mounted suspension, so that the base 10 has sufficient strength and rigidity to adapt to the harsh vibration and impact environment of rail transit; the ventilation ribs 15 are used to form the heat exchange cavity 14 to arrange the ventilation and heat dissipation structure. Since the pull plates 16 and ventilation ribs 15 are alternately arranged along the circumference, while ensuring the load-bearing capacity of the base 10, sufficient circumferential ventilation area is reserved for the heat exchange cavity 14, which better balances the mutually restrictive requirements of the structural strength of the base 10 and the ventilation duct arrangement. In this embodiment, the three pull plates 16 and the three heat exchange chambers 14 can be arranged alternately and roughly evenly along the circumference. The circumferential range occupied by the pull plates 16 and the circumferential range occupied by the heat exchange chambers 14 can be determined based on the stress calculation of the base 10 and the temperature rise test results.

[0033] like Figure 3 As shown, each heat exchange chamber 14 is equipped with a radiator 17. The radiator 17 includes a heat-conducting substrate and multiple heat dissipation fins disposed on the heat-conducting substrate. The heat-conducting substrate is fixed to the outer circumferential surface of the outer cylinder 12, and the multiple heat dissipation fins are located on the side of the heat-conducting substrate away from the outer cylinder 12 and extend from the heat-conducting substrate toward the corresponding ventilation rib 15. The internal circulating air flowing through the heat exchange chamber 14 passes between adjacent heat dissipation fins, transferring heat to the heat dissipation fins and the heat-conducting substrate. The heat is then transferred through the cylinder wall of the outer cylinder 12 located between the heat-conducting substrate and the cooling channel 13 to the cooling medium in the cooling channel 13. To increase the heat dissipation area, in this embodiment, the heat dissipation fins are preferably configured as two sets that are crisscrossed, that is, one set of heat dissipation fins extends along the axial direction of the rotor 30 and the other set of heat dissipation fins extends along the circumferential direction of the base 10; as an optional implementation, the heat dissipation fins may also extend only along the axial direction or only along the circumferential direction, or be configured as needle-shaped, corrugated, or other forms.

[0034] To reduce the contact thermal resistance between the radiator 17 and the outer cylinder 12, a thermally conductive material layer 18 is provided between the thermally conductive substrate and the outer peripheral surface of the outer cylinder 12. The thermally conductive material layer 18 fills the tiny gaps at the contact surfaces between the thermally conductive substrate and the outer cylinder 12, allowing the heat absorbed by the radiator 17 to be more fully transferred to the cylinder wall of the outer cylinder 12. The thermally conductive material layer 18 is preferably thermally conductive silicone grease. As an optional implementation, it can also be a thermally conductive pad, thermally conductive adhesive, or other thermally conductive material capable of filling the contact gaps. The radiator 17 can be fixed to the outer peripheral surface of the outer cylinder 12 by bolt tightening, snap-fitting, or other methods. When the radiator 17 is connected to the outer cylinder 12 by continuous welding, the thermally conductive material layer 18 can be omitted depending on the welding contact state. As another implementation, the radiator 17 can also be integrally formed with the outer wall of the outer cylinder 12, that is, the heat dissipation fins are directly formed on the outer peripheral surface of the outer cylinder 12. In this case, there is no need to provide a separate thermally conductive material layer 18 between the heat dissipation fins and the outer cylinder 12. Since the radiator 17, the outer cylinder 12 wall and the cooling channel 13 are arranged in the radial direction, the heat absorbed by the radiator 17 can enter the cooling medium through a shorter metal heat transfer path, thereby improving the efficiency of heat transfer from the internal circulating air to the cooling medium.

[0035] Please see Figure 1 The rotor 30 is provided with a first rotor air duct 31 extending axially. The two ends of the first rotor air duct 31 are connected to the first end space 50 and the second end space 60, respectively, so that air can pass through the rotor 30 axially and exchange heat with the rotor 30. The first rotor air duct 31 can be formed by a through hole that runs through the rotor 30 axially, or it can be formed by multiple axial through holes spaced apart circumferentially along the rotor 30. When it is formed by multiple through holes, the shape, number and circumferential position of each through hole can be determined according to the magnetic circuit direction of the rotor 30, the position of the permanent magnet and the required flow area. Each through hole can be a circular hole, an oblong hole or a channel with other cross-sectional shapes.

[0036] A first pressure ring and a second pressure ring are fixed to both ends of the rotor 30 along the axial direction, respectively. The first and second pressure rings are used to press the components at the ends of the rotor 30 axially. The first pressure ring has a plurality of first guide holes connecting the first end space 50 and the first rotor air duct 31, and the second pressure ring has a plurality of second guide holes connecting the second end space 60 and the first rotor air duct 31. Both the first and second guide holes are inclined relative to the axial direction of the rotor 30, and the axes of the first and second guide holes extend toward the ends of the adjacent stator windings 21, that is, the extended lines of the inclined guide holes are roughly aligned with the ends of the stator windings 21. As a result, the air discharged from the first and second guide holes can be guided to the vicinity of the ends of the stator windings 21, thereby enhancing the cooling of this heat-concentrated part of the stator windings 21. As some alternative implementations, the first and second guide holes can be straight holes, arc-shaped holes, or channels with cross-sections that gradually change along the axial direction. Their tilt angle relative to the axial direction can be adaptively adjusted according to the actual forming dimensions of the stator winding 21 end to expand the coverage of cooling air to the winding end.

[0037] As an optional implementation, the air gap between the stator 20 and the rotor 30 can also be connected to the first end space 50 and the second end space 60, respectively, thereby forming an air gap branch connected in parallel with the first rotor air duct 31. In this case, a portion of the internal circulating air flows through the first rotor air duct 31, and another portion of the internal circulating air flows through the air gap between the stator 20 and the rotor 30, with the two portions of air merging at the end space. This air gap branch can cool the air gap area, but it is not a necessary structure for forming an internal circulating air path; if it is necessary to further improve the heat dissipation efficiency of the air gap area, the axial length of the air gap or the size of the stator slot can be appropriately increased to increase the airflow through the air gap.

[0038] like Figure 1As shown, the spaces at both ends of the rotor 30 within the base 10 form a first end space 50 and a second end space 60, respectively. Each end space accommodates the corresponding end of the stator winding 21 and is adjacent to the end of the rotor 30. The first end space 50, the first rotor air duct 31, the second end space 60, and the heat exchange chamber 14 are connected end-to-end, forming an internal circulation air path isolated from the outside. When the airflow drive assembly operates, the air within the base 10 circulates within this internal circulation air path: when flowing through the first rotor air duct 31, it exchanges heat with the rotor 30; when flowing through the first end space 50 and the second end space 60, it exchanges heat with the ends of the stator winding 21 and the rotor 30; when flowing through the heat exchange chamber 14, it transfers heat to the cooling medium in the cooling channel 13 via the radiator 17 and the outer cylinder 12, then returns and continues the next cycle. Since the internal circulation airway is isolated from the outside, there is no need to continuously send external air carrying ferromagnetic particles and dust into the first rotor airway 31, the first end space 50 and the second end space 60, thus reducing the chance of ferromagnetic particles and dust entering the air gap between the stator 20 and the rotor 30 with the cooling air.

[0039] The airflow drive assembly is connected to and rotates with the shaft 40. Please refer to the following: Figure 1 and Figure 6 In this embodiment (i.e.) Figure 1 In the embodiment shown, the airflow drive assembly includes a first rotating member 71 located at the non-transmission end and a second rotating member 74 located at the transmission end. The first rotating member 71 is equipped with an inner circulation blade section 72 and an outer ventilation blade section 73. The second rotating member 74 is only used to separate the first outer ventilation space 81 from the first end space 50 and does not have blades on itself.

[0040] Specifically, such as Figure 6 As shown, the first rotating member 71 includes a hub fixedly sleeved on the rotating shaft 40 and a partition plate connected to the outer periphery of the hub. The inner circulation blade section 72 and the outer ventilation blade section 73 are located on opposite sides of the partition plate. The inner circulation blade section 72 includes a plurality of inner circulation blades spaced apart circumferentially along the first rotating member 71, at least partially located within the second end space 60; the outer ventilation blade section 73 includes a plurality of outer ventilation blades spaced apart circumferentially along the first rotating member 71, at least partially located within the second outer ventilation space 82; the partition plate separates the second end space 60 from the second outer ventilation space 82. When the rotating shaft 40 rotates, the inner circulation blade section 72 performs work on the air within the second end space 60, creating a pressure difference between the two ends of the inner circulation air path, thereby driving the air within the base 10 to circulate along the inner circulation air path; the outer ventilation blade section 73 performs work on the air within the second outer ventilation space 82, driving the external air to flow along the external ventilation path described later.

[0041] Regarding the separation between the first end space 50, the second end space 60, and the corresponding external ventilation space, this embodiment adopts the following structure: the first external ventilation space 81 and the first end space 50 are not separated by a separate stationary partition, but are separated by a second rotating member 74 that rotates with the rotating shaft 40 in conjunction with the inner wall of the base 10. Specifically, the second rotating member 74 (e.g., Figure 1 As shown, the internal space on the drive end side of the base 10 is divided into a first end space 50 and a first external ventilation space 81, which are isolated from each other. A first annular sealing portion is provided on the inner wall of the drive end side of the base 10. The first annular sealing portion rotatably engages with and seals the outer periphery of the second rotating member 74, thereby preventing air leakage between the first end space 50 and the first external ventilation space 81 while the second rotating member 74 rotates with the rotating shaft 40. Correspondingly, the partition of the first rotating member 71 divides the internal space on the non-drive end side of the base 10 into a second end space 60 and a second external ventilation space 82, which are isolated from each other. A second annular sealing portion is provided on the inner wall of the non-drive end side of the base 10. The second annular sealing portion rotatably engages with and seals the outer periphery of the first rotating member 71 (e.g., the outer edge of the partition), thereby preventing air leakage between the second end space 60 and the second external ventilation space 82. The first and second annular sealing portions can be labyrinth seal structures or contact seal structures with sealing rings. Therefore, without the need for additional static partitions between the end space and the external ventilation space, the internal circulation air path and the external ventilation path can be isolated from each other by utilizing the dynamic sealing fit between the first rotating member 71 and the second rotating member 74 that rotate with the rotating shaft 40 and the inner wall of the base 10, making the structure more compact.

[0042] As an optional implementation, separate first and second separators can also be provided between the first end space 50 and the first external ventilation space 81, and between the second end space 60 and the second external ventilation space 82. The first and second separators can be, for example, annular separator plates fixed to the inner wall of the base 10 or the end cover, with a sealing structure between their inner edges and the rotating shaft 40 or the corresponding rotating component, thus isolating the end space from the corresponding external ventilation space. Furthermore, the inner circulation blade portion 72 and the outer ventilation blade portion 73 are not limited to being integrated onto the same first rotating component 71. In another embodiment, please refer to... Figure 2 The internal circulation blade section 72 is disposed on the first rotating member 71 located at the non-drive end, while the external ventilation blade section 73 is disposed on the second rotating member 74 located at the drive end. That is, the two rotating members located at opposite ends of the rotor 30 axially respectively handle the internal circulation air supply and the external air supply. In this case, the second rotating member 74 is equipped with the external ventilation blade section 73 and handles the external air supply. In this other embodiment, the flow direction of the external air can also be... Figure 1The illustrated embodiment is the opposite. Regardless of the arrangement described above, the internal circulating air and the external air are separated by a partition structure, and the two air paths will not connect to each other due to changes in the position of the rotating component.

[0043] Please continue reading. Figure 1 The rotor 30 is also provided with a second rotor air duct 32 extending axially. The second rotor air duct 32 is isolated from the first rotor air duct 31 and is not connected to the first end space 50, the second end space 60, or the air gap between the stator 20 and the rotor 30. A first external ventilation space 81 and a second external ventilation space 82 are respectively formed at both axial ends of the rotor 30 within the base 10. The first external ventilation space 81 and the first end space 50 are located at the same axial end of the rotor 30 and are isolated from each other. The second external ventilation space 82 and the second end space 60 are located at the same axial end of the rotor 30 and are isolated from each other. The two ends of the second rotor air duct 32 are connected to the first external ventilation space 81 and the second external ventilation space 82, respectively. The first external ventilation duct and the second external ventilation duct are respectively provided on the drive end side and the non-drive end side of the base 10. The first external ventilation space 81 and the second external ventilation space 82 are connected to the outside through the first external ventilation duct and the second external ventilation duct, respectively, thus forming an external ventilation path isolated from the internal circulation air path.

[0044] When the external ventilation blades 73 rotate with the shaft 40, they push external air to flow along the aforementioned external ventilation path. Figure 1 In the embodiment shown, external air enters through the first external ventilation duct at the transmission end, flows sequentially through the first external ventilation space 81, the second rotor air duct 32, and the second external ventilation space 82, and is then discharged through the second external ventilation duct at the non-transmission end. When the external air flows through the above path, it can flow through the area near the transmission end support and the oil return ring 93, as well as the area near the non-transmission end support, thereby carrying away some of the heat from these parts.

[0045] It should be noted that the hole wall of the second rotor air duct 32 and the partition structure at the end of the rotor 30 prevent external air from entering the first rotor air duct 31 and the air gap between the stator 20 and the rotor 30. When the direction of rotation of the shaft 40, the bending direction of the external ventilation blades, or the setting position of the external ventilation blades 73 are changed, the flow direction of the external air can be changed accordingly. This embodiment does not limit the flow direction of the external air.

[0046] Furthermore, the second external ventilation duct at the non-transmission end (or the first external ventilation duct at the transmission end) can be configured as a tortuous channel structure, having multiple channel segments extending in different directions, with turning parts between adjacent channel segments, and the inlet and outlet of the channel being staggered axially or radially. On the one hand, the tortuous external ventilation duct can lengthen the path of sound propagation, causing the aerodynamic and electromagnetic noise generated inside the motor to be attenuated through multiple reflections and deflections within the tortuous channel; on the other hand, the tortuous external ventilation duct can reduce the periodic pressure fluctuations caused by the direct impact of external air on the end cover stiffener, thereby reducing the ventilation noise of the motor during high-speed operation and improving the overall acoustic comfort of the vehicle.

[0047] Please refer to the following: Figure 1 and Figure 7 The permanent magnet motor in this embodiment also includes a gearbox 90, a coupling 91, a gear 92, and an oil return ring 93. The gearbox 90 is connected to the transmission end of the base 10, and the motor and the gearbox 90 share a support portion located at the transmission end. The coupling 91 is fixedly sleeved on the transmission end of the rotating shaft 40, and the gear 92 is disposed inside the gearbox 90 and connected to the coupling 91. For example, the coupling 91 and the gear 92, which is a pinion, are fixedly connected by a large bolt. The coupling 91 and the rotating shaft 40 can be connected by an interference fit, thereby transmitting the power of the rotating shaft 40 to the transmission mechanism of the gearbox 90 via the coupling 91 and the gear 92.

[0048] like Figure 7 As shown, an oil return ring 93 is disposed inside the gearbox 90 and surrounds the coupling 91. An oil return gap is formed between the inner circumferential surface of the oil return ring 93 and the outer circumferential surface of the coupling 91. The inner circumferential surface of the oil return ring 93 is provided with multiple oil collecting grooves 931 extending circumferentially and spaced axially, and a confluence groove 932 communicating with the multiple oil collecting grooves 931. The gearbox 90 has an oil return hole 94 on its wall. One end of the oil return hole 94 communicates with the confluence groove 932, and the other end communicates with the oil cavity of the gearbox 90. When the lubricating oil in the gearbox 90 enters the oil return gap during the operation of the coupling 91 and the gear 92, it first enters the multiple oil collecting grooves 931 extending circumferentially, then is collected by the confluence groove 932, and then returns to the oil cavity of the gearbox 90 through the oil return hole 94, thereby preventing the lubricating oil from accumulating in the oil return gap. In this embodiment, multiple oil collecting grooves 931 are arranged axially at intervals on the inner circumferential surface of the oil return ring 93, and the confluence groove 932 extends axially and connects the multiple oil collecting grooves 931. As an optional implementation, the confluence groove 932 may also extend obliquely relative to the axial direction of the rotating shaft 40.

[0049] Because the airflow drive assembly creates a relatively low air pressure on the side near the motor when driving airflow inside the motor, a pressure balance channel 95 is provided between the oil return ring 93 and the gearbox wall 90 to prevent lubricating oil in the gearbox 90 from being drawn into the motor under this negative pressure. One end of the pressure balance channel 95 is connected to the end of the oil return gap near the rotor 30, and the other end is connected to the outside and isolated from the internal circulation air path. The pressure balance channel 95 makes the air pressure at the end of the oil return gap near the motor similar to the external atmospheric pressure, reducing the pressure difference between the end of the oil return gap and the outside, thus making it less likely for lubricating oil to move into the motor under the suction effect of the rotating parts. In addition, when the external air in the aforementioned external ventilation path flows through the outer periphery of the oil return ring 93, it can also carry away some of the heat in the oil return area.

[0050] The working process of the permanent magnet motor in this embodiment is briefly described below. Under normal traction conditions, the shaft 40 drives the rotor 30, the first rotating component 71, and the second rotating component 74 to rotate. The inner circulation blades 72 on the first rotating component 71 push the air in the base 10 to circulate along the inner circulation air path. When the air flows through the end of the stator winding 21 and the first rotor air duct 31, it absorbs heat and then enters the heat exchange chamber 14 and flows through the radiator 17. The radiator 17 transfers the heat in the air through the cylinder wall of the outer cylinder 12 to the cooling medium in the cooling channel 13. At the same time, the heat of the stator 20 is transferred through the inner cylinder 11 to the cooling medium in the cooling channel 13. After entering through the cooling medium inlet, the cooling medium moves forward circumferentially and repeatedly turns axially under the guidance of the staggered guide vanes 133, flowing through the radially opposite areas of each heat exchange chamber 14 in sequence, receiving the heat transferred from the radiator 17 and the cylinder wall of the base 10, and then exiting the motor through the cooling medium outlet. After heat exchange, the internal circulating air returns and re-enters the first rotor duct 31, thus continuously circulating. The internal circulating air and the cooling medium are separated by the cylinder wall of the base 10, and the two do not mix directly. At the same time, the external ventilation blades 73 on the first rotating component 71 push the external air along the external ventilation path through the second rotor duct 32, cooling the support parts of the transmission end and non-transmission end, the oil return ring 93, and the area near the gearbox 90.

[0051] In special operating conditions such as breakdown rescue towing or towing without cooling, the locomotive is not raised and the motor is not powered, but the shaft 40 still rotates at high speed while being towed by the wheelset. At this time, even if the circulation of the cooling medium of the whole vehicle stops, the airflow drive assembly still rotates with the shaft 40: the internal circulation air path driven by the internal circulation blade section 72 can still make the temperature distribution of various parts inside the motor tend to be uniform, and the external ventilation path driven by the external ventilation blade section 73 can still continuously remove the heat from the transmission end and non-transmission end support parts, thereby preventing the support parts from overheating and being damaged due to high-speed dry friction, and ensuring the reliability of the motor operation under special operating conditions.

[0052] It should be noted that one or more heat exchange chambers 14 can be arranged along the circumference of the base 10. Multiple heat exchange chambers 14 can have the same flow cross section, or different flow cross sections can be used depending on the position of the pull plate 16. The flow cross section of the heat exchange chamber 14, the total flow area of ​​the guide holes on the first and second pressure rings, and the total flow area of ​​the first rotor air duct 31 can be set in combination with the length of each section and the local resistance. When the flow capacity of the above sections is relatively close, it is beneficial to reduce the flow loss caused by excessive throttling in a certain part. However, it is not required that the flow area at each place be completely equal in all embodiments. The specific area relationship can be determined according to the ventilation calculation and temperature rise test of the prototype.

[0053] In summary, the permanent magnet motor of this embodiment forms an internal circulation airway isolated from the outside world by connecting the first end space 50, the first rotor air duct 31, the second end space 60 and the heat exchange cavity 14 end to end. The airflow drive component drives the existing air circulation in the frame 10 to transport the heat from the rotor 30 and the stator winding 21 to the heat exchange cavity 14 on the outer periphery of the frame 10. The heat is then continuously carried away by the cooling medium flowing in the cooling channel 13. This reduces the entry of ferromagnetic particles and dust carried by the external air into the motor while achieving efficient heat dissipation inside the motor. Furthermore, the heat exchange efficiency between the internal circulating air and the cooling medium is improved through the cooling channel 13 between the inner cylinder 11 and the outer cylinder 12, the heat exchange cavity 14 formed by the staggered guide vanes 133 and ventilation ribs 15, the radiator 17 and the heat-conducting material layer 18 in the heat exchange cavity 14; the external ventilation path formed by the second rotor air duct 32 and the external ventilation blades 73, which is isolated from the internal circulating air path, achieves directional cooling of the bearing and drive side parts without allowing external air to enter the internal circulating air path, especially meeting the cooling requirements of special working conditions such as no-cooling drive; the alternating arrangement of the pull plate 16 and the ventilation ribs 15 along the circumference takes into account both the structural strength of the base 10 and the arrangement of the ventilation duct; the oil collection groove 931, the confluence groove 932 and the oil return hole 94 of the oil return ring 93 and the air pressure balance channel 95 solve the problem of the backflow of lubricating oil in the gearbox 90 and prevent lubricating oil from being sucked into the motor.

[0054] The above description is merely a specific embodiment of the present invention, used to illustrate the technical solution of the present invention and not to limit it. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A permanent magnet motor, characterized in that, Includes the frame, stator, rotor, shaft, and airflow drive components; The stator is fixed inside the machine base, and the rotor is located radially inside the stator and is fixedly sleeved on the rotating shaft; The base has a first end space and a second end space formed on both sides of the rotor's axial direction. The rotor is provided with a first rotor air duct extending along its own axial direction. The two ends of the first rotor air duct are respectively connected to the first end space and the second end space. The base is provided with a heat exchange cavity, and the two ends of the heat exchange cavity are respectively connected to the first end space and the second end space, so that the first end space, the first rotor air duct, the second end space and the heat exchange cavity are connected end to end to form an internal circulation air path; The base is also provided with a cooling channel for the flow of cooling medium. The cooling channel is thermally connected to the heat exchange cavity so that the cooling medium absorbs the heat carried by the air flowing through the heat exchange cavity. The airflow drive component is connected to the rotating shaft and is used to drive the air in the base to circulate along the internal circulation air path.

2. The permanent magnet motor according to claim 1, characterized in that, The base includes an inner cylinder and an outer cylinder sleeved around the outer periphery of the inner cylinder, and the stator is fixed to the inner periphery of the inner cylinder; The cooling channel is formed between the outer circumferential surface of the inner cylinder and the inner circumferential surface of the outer cylinder, and the base is provided with a cooling medium inlet and a cooling medium outlet respectively communicating with the cooling channel; The heat exchange cavity is located radially outside the outer cylinder, so that the cooling channel is located between the stator and the heat exchange cavity.

3. The permanent magnet motor according to claim 2, characterized in that, The cooling channel has a first sidewall and a second sidewall disposed opposite to each other along the axial direction of the rotor; The cooling channel is provided with a plurality of guide vanes spaced apart along the circumference of the inner cylinder, and the radial inner edge and radial outer edge of each guide vane are respectively connected to the inner cylinder and the outer cylinder; Of the two adjacent guide vanes, one extends from the first sidewall toward the second sidewall, and the other extends from the second sidewall toward the first sidewall. A flow gap is formed between the free end of each guide vane and the sidewall it faces, so that a cooling medium flow path is formed in the cooling channel that extends circumferentially and folds back and forth axially.

4. The permanent magnet motor according to claim 2, characterized in that, The outer circumference of the outer cylinder is provided with a plurality of ventilation ribs spaced apart along the circumference of the outer cylinder, and each ventilation rib extends along the axial direction of the rotor. Each of the ventilation ribs is spaced apart from the outer circumferential surface of the outer cylinder and forms a heat exchange cavity with the outer circumferential surface of the outer cylinder. Multiple heat exchange cavities are distributed at intervals along the circumference of the outer cylinder. The two ends of each heat exchange cavity are respectively connected to the first end space and the second end space.

5. The permanent magnet motor according to claim 4, characterized in that, Each of the aforementioned heat exchange chambers is equipped with a radiator; The radiator includes a heat-conducting substrate and a plurality of heat-dissipating fins disposed on the heat-conducting substrate. The heat-conducting substrate is fixed to the outer peripheral surface of the outer cylinder. The plurality of heat-dissipating fins are located on the side of the heat-conducting substrate away from the outer cylinder and extend from the heat-conducting substrate toward the corresponding ventilation rib. A thermally conductive material layer is provided between the thermally conductive substrate and the outer peripheral surface of the outer cylinder. The cylinder wall located between the thermally conductive substrate and the cooling channel in the outer cylinder is in thermal contact with the thermally conductive substrate and the cooling medium, respectively.

6. The permanent magnet motor according to claim 4, characterized in that, The outer periphery of the outer cylinder is also provided with a plurality of pull plates, each of which extends along the axial direction of the rotor and its two axial ends are respectively fixedly connected to the two axial ends of the base. Multiple pull plates and multiple ventilation ribs are alternately arranged along the circumference of the outer cylinder.

7. The permanent magnet motor according to claim 1, characterized in that, The airflow drive assembly includes at least one rotating member connected to the rotating shaft, and an inner circulation blade portion disposed on at least one of the rotating members; The inner circulation blade section includes a plurality of inner circulation blades spaced circumferentially along the corresponding rotating member, and the plurality of inner circulation blades are at least partially located in one of the first end space and the second end space.

8. The permanent magnet motor according to claim 1, characterized in that, The rotor is fixed with a first pressure ring and a second pressure ring at both ends of its axial direction, respectively. The first pressure ring is provided with a plurality of first guide holes connecting the first end space and the first rotor air duct, and the second pressure ring is provided with a plurality of second guide holes connecting the second end space and the first rotor air duct; Both the first guide hole and the second guide hole are inclined relative to the axial direction of the rotor, and the axes of the first guide hole and the second guide hole extend toward the ends of adjacent stator windings, respectively.

9. The permanent magnet motor according to claim 7, characterized in that, The rotor is also provided with a second rotor duct that extends axially and is isolated from the first rotor duct. The base also forms a first external ventilation space and a second external ventilation space at both axial ends of the rotor. The first external ventilation space and the first end space are located at the same axial end of the rotor and are isolated from each other. The second external ventilation space and the second end space are located at the other axial end of the rotor and are isolated from each other. The two ends of the second rotor air duct are respectively connected to the first external ventilation space and the second external ventilation space. The first external ventilation space and the second external ventilation space are respectively connected to the outside through the first external ventilation duct and the second external ventilation duct on both sides of the machine base axis, so as to form an external ventilation path that is isolated from the internal circulation air path. The airflow drive assembly further includes an external ventilation blade portion disposed on at least one of the rotating members. The external ventilation blade portion includes a plurality of external ventilation blades spaced apart circumferentially along the corresponding rotating members. The plurality of external ventilation blades are at least partially located within one of the first external ventilation space and the second external ventilation space.

10. The permanent magnet motor according to claim 1, characterized in that, It also includes gearboxes, couplings, gears, and oil return rings; The gearbox is connected to the transmission end of the machine base, the coupling is fixedly sleeved on the transmission end of the rotating shaft, and the gear is disposed in the gearbox and connected to the coupling. The oil return ring is disposed inside the gearbox and surrounds the coupling. An oil return gap is formed between the inner circumferential surface of the oil return ring and the outer circumferential surface of the coupling. The inner circumferential surface of the oil return ring is provided with a plurality of oil collecting grooves extending circumferentially and spaced axially, and a confluence groove communicating with the plurality of oil collecting grooves. The gearbox wall is provided with an oil return hole. One end of the oil return hole is connected to the confluence groove, and the other end is connected to the oil cavity of the gearbox. A pressure balance channel is also provided between the oil return ring and the gearbox wall. One end of the pressure balance channel is connected to the end of the oil return gap near the rotor, and the other end is connected to the outside and isolated from the internal circulation air path.

Images