Permanent magnet direct-drive traction electric motor for built-in bogie axle box

Abstract

The present invention relates to the field of traction electric motors. Specifically provided is a permanent magnet direct-drive traction electric motor for a built-in bogie axle box, the electric motor comprising a central rotating shaft, a rotor assembly, a stator assembly and a cooling system, wherein the rotor assembly is fixedly connected to the central rotating shaft, the stator assembly is located on the outer side of the rotor assembly, and end cover assemblies are connected to the central rotating shaft and located on the outer sides of two axial ends of the stator assembly and the rotor assembly; and the cooling system comprises an air cooling system and a water cooling system, the air cooling system being arranged between the axial ends of the rotor assembly and the end cover assemblies, the water cooling system comprising a water cooling assembly I connected to the end of the stator assembly that is away from the central rotating shaft, the water cooling assembly I being located between the two end cover assemblies and located on the outer side of the stator assembly, and the water cooling system further comprising water cooling assemblies II located on the inner sides of the end cover assemblies. In the present solution, the electric motor has a simple structure, and the electric motor and bearings can be cooled by means of the water cooling assembly I, the water cooling assemblies II and the air cooling system, such that the hot spot temperature of the electric motor and the bearing temperature can be reduced, and the size of the electric motor can be reduced.

Description

A permanent magnet direct drive traction motor for use in a bogie axle box Technical Field

[0001] The present invention relates to the technical field of traction motors, and in particular to a permanent magnet direct-drive traction motor for use in a bogie axle box. Background Art

[0002] With the rapid development of rail transit, performance requirements for traction drives, such as power and economy, have continued to increase, driving the continuous development of vehicle drive technology. Compared to traditional traction drive systems, permanent magnet direct-drive traction systems eliminate the gearbox. Instead, motor torque is transmitted directly to the wheelset via a coupling, making the traction drive system more compact while improving transmission efficiency. Furthermore, the noise, lubrication, sealing, and maintenance issues associated with gearbox transmission are eliminated, improving drive system reliability and reducing operational costs.

[0003] In the existing technical solutions, the permanent magnet direct drive bogies of rail vehicles mostly have external axle boxes, in which the axial installation size limit of the permanent magnet direct drive motor is large. If the bogie axle box adopts a built-in structure, it will be beneficial for the vehicle to pass through small-radius urban lines, but there are the following problems: 1. After the bogie axle box is built-in, the axial size limit of the traction motor installation is reduced, and the axial size of the permanent magnet direct drive motor will not be able to meet the installation requirements of the bogie; 2. After the bogie axle box is built-in, the heat dissipation and cooling capacity of the permanent magnet direct drive motor is poor. In the existing technology, the following patents involve permanent magnet direct drive motors:

[0004] 1. Patent application number "201611053634.9" and titled "Locomotive Direct-Drive Permanent Magnet Traction Motor" include laminations and pull plates. A housing is welded between adjacent pull plates. The outer circle of the laminations, pull plates, and housing form an air duct. Wedges are provided between the lamination teeth, and the wedges and lamination teeth form an air duct. The hollow shaft is made of high-strength forged steel with tooth slots on the end face. The end cover assembly is made of cast aluminum. A windshield extends from the end cover assembly, and the end of the windshield is closely attached to the end face of the wedge. The windshield and the wedge end face are provided with sealing strips. The motor structure in this scheme is relatively simple, with low transmission loss, but the structure is still not streamlined. Furthermore, the motor is cooled by forced ventilation, which has a complex cooling structure. The bearings lack a dedicated cooling structure, which will lead to high bearing temperatures.

[0005] 2. Patent application number 201510826523.6, entitled "A Permanent Magnet Synchronous Direct-Drive Motor for Rail Transit," describes a front and rear cover assembly that snaps onto the ends of the direct-drive motor's stator assembly. The wheel axle passes through these two assemblies, with bearings positioned between the axle and the front and rear cover assemblies. The direct-drive motor's rotor assembly is located within the stator assembly and secured to the axle, with the axis of the rotor assembly coinciding with the axis of the axle. This solution features a small and lightweight motor. The motor rotor assembly is shared with the axle of the rail transit traction system, directly driving the axle and improving transmission efficiency. However, the structure is not streamlined enough, and the motor is cooled by water using spiral channels, resulting in uneven temperatures at both ends of the motor. The lack of internal air circulation within the motor results in uneven internal temperatures, leading to high hot spots in the motor and high bearing temperatures.

[0006] In summary, how to design a permanent magnet direct-drive traction motor for use in a bogie axle box that has a simple structure, miniaturized design, and can improve the cooling and heat dissipation efficiency of the permanent magnet direct-drive traction motor is an urgent problem that needs to be solved.

[0007] Summary of the Invention

[0008] In order to solve the above problems, the present invention provides a permanent magnet direct drive traction motor for use in a bogie axle box, which can reduce the hot spot temperature of the motor winding and the bearing temperature, and within the same temperature limit, can also reduce the axial size of the motor.

[0009] To achieve the above-mentioned objectives, the present invention proposes the following technical solutions: a permanent magnet direct-drive traction motor for use in a bogie axle box, comprising a central rotating shaft, a rotor assembly, a stator assembly and a cooling system, wherein the rotor assembly is fixedly connected to the central rotating shaft, and the stator assembly is located outside the rotor assembly; the central rotating shaft is connected to an end cover assembly located outside the axial ends of the stator assembly and the rotor assembly, the cooling system comprises an air cooling system and a water cooling system, the air cooling system is arranged between the axial end of the rotor assembly and the end cover assembly, and the water cooling system comprises a water cooling assembly connected to an end of the stator assembly away from the central rotating shaft, and the water cooling assembly is located between the end cover assemblies.

[0010] Furthermore, the water cooling component 1 includes an inner water jacket, an outer water jacket and a stator water channel, and the inner water jacket is connected to the stator assembly. Flanges are connected between the ends of the inner water jacket and the outer water jacket and the end cover assembly, and the stator water channel is located between the inner water jacket, the outer water jacket and the flange.

[0011] Furthermore, water channel ribs are evenly distributed in the stator water channel and the length of the water channel ribs is shorter than the length of the outer water jacket and the inner water jacket; the water channel ribs include water channel rib 1 and water channel rib 2 respectively connected to the flanges on both sides, and water channel rib 1 and water channel rib 2 are arranged at intervals to form a round-trip water channel in the stator water channel.

[0012] Furthermore, the water cooling system also includes a water cooling component 2 located at the end cover assembly; a cooling cavity is formed between the end cover assembly, the flange, the stator assembly, the rotor assembly and the central rotating shaft, and the water cooling component 2 includes an isolation plate and an end cover water channel, the isolation plate is provided on the end cover assembly and is located in the cooling cavity, and the end cover water channel is formed between the isolation plate and the end cover assembly.

[0013] Furthermore, a water retaining ring is provided at the end where the water channel rib is connected to the flange.

[0014] Furthermore, pressure rings are provided at both axial ends of the rotor assembly, and the air cooling system includes a fan located on the pressure ring. The fan is located in the cooling cavity and on the inner side of the isolation plate.

[0015] Furthermore, the end cover assembly includes a non-driving end cover assembly and a driving end cover assembly; the pressure ring located on one side of the non-driving end cover assembly and the pressure ring located on one side of the driving end cover assembly are respectively the first pressure ring and the second pressure ring, and the fan on the first pressure ring and the fan on the second pressure ring are respectively the first fan and the second fan; the first pressure ring and the second pressure ring are respectively arranged according to the shape of the central rotating shaft and the shape specifications of the first pressure ring and the second pressure ring are different, and the first fan and the second fan are the same or different.

[0016] Furthermore, the non-drive end cover assembly includes an end cover 1, a ball bearing and an oil seal 1, the ball bearing is located between the end cover 1 and the central rotating shaft, and the oil seal 1 is located between the end cover 1 and the central rotating shaft and on the outside of the ball bearing.

[0017] Furthermore, the drive end cover assembly includes end cover 2, a cylindrical bearing and oil seal 2, the cylindrical bearing is located between end cover 2 and the central rotating shaft, and the oil seal 2 is located between end cover 2 and the central rotating shaft and on the outside of the cylindrical bearing.

[0018] Furthermore, the stator assembly includes a stator core and a stator winding, and the stator core is formed by stacking silicon steel sheets and is heat-shrink-fitted into a water-cooling assembly; the rotor assembly includes a rotor core and magnets, and the rotor core is formed by stacking silicon steel sheets and is heat-shrink-fitted onto the central rotating shaft; the rotor core is provided with a topological structure of "U-shaped slot" and "type I slot", and the magnets are embedded in the "U-shaped slot" and "type I slot", and the magnets are located inside the rotor core.

[0019] The beneficial effects of the present invention are:

[0020] 1. The water channel of the water-cooling assembly 1 in the present invention can cool the motor stator assembly, and the water-cooling assembly 2 can cool the bearings and the inside of the motor, while also reducing the bearing temperature. The air cooling system can make the temperature inside the motor more uniform and also reduce the hot spot temperature of the motor.

[0021] 2. The motor structure of the present invention is simple, and within the same temperature limit, the axial dimension of the motor can be reduced, and the volume of the motor can be reduced.

[0022] 3. The rotor core of the present invention adopts a topological structure including U-shaped slots and I-shaped slots, which can improve the power density and further reduce the size of the motor, thereby meeting the requirements of the built-in structure of the bogie axle box on the motor size limit. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a schematic diagram of the overall structure of a motor provided by an embodiment of the present invention.

[0024] FIG2 is a schematic structural diagram of a water cooling assembly 1 provided in an embodiment of the present invention.

[0025] Figure numerals: central shaft 1, stator water channel 2, flange 3, water channel rib 1 4, water channel rib 2 5, cooling chamber 6, isolation plate 7, end cover water channel 8, water retaining ring 9, non-drive end cover assembly 10, drive end cover assembly 11, first pressure ring 12, second pressure ring 13, first fan 14, second fan 15, end cover 1 16, ball bearing 17, oil seal 1 18, end cover 2 19, cylindrical bearing 20, oil seal 2 21, stator core 22, stator winding 23, rotor core 24, magnet 25, inner water jacket 26, outer water jacket 27. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with Figures 1 and 2 and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0027] A permanent magnet direct-drive traction motor for use in a bogie axlebox, as shown in FIG1 , comprises a central rotating shaft 1, a rotor assembly, a stator assembly, and a cooling system. The central rotating shaft 1 is a hollow shaft structure, and the rotor assembly is fixedly connected to the central rotating shaft 1. The rotor assembly comprises a rotor core 24 and magnets 25. The rotor core 24 is formed by laminating high-permeability, low-loss silicon steel sheets and is shrink-fitted onto the central rotating shaft 1 through an interference fit. Pressure rings are provided at both axial ends of the rotor assembly. The pressure rings are arranged at both axial ends of the rotor core 24, and the rotor core 24 is fixed to the central rotating shaft 1 through interference fit by the pressure rings. The rotor core 24 is provided with a "U-shaped slot" and "slot" topology structure, and the magnets 25 are embedded in the "U-shaped slot" and "slot" slots. The rotor core 24 as a whole has a "U+slot" topology structure, which can increase the reluctance torque, thereby improving the power density and torque density of the motor.

[0028] Connected to the central rotating shaft 1 are end cap assemblies located outside the axial ends of the stator and rotor assemblies. The cooling system includes an air cooling system and a water cooling system. The air cooling system is located between the axial end of the rotor assembly and the end cap assemblies. The water cooling system includes a water cooling assembly 1 connected to the end of the stator assembly away from the central rotating shaft 1, and located between the end cap assemblies. The stator assembly is located outside the rotor assembly and includes a stator core 22 and stator windings 23. The stator core 22 is formed by laminating high-permeability, low-loss silicon steel sheets and is secured by welding with clips. It is then shrink-fitted into the water cooling assembly 1. The magnets 25 are located between the rotor core 24 and the stator core 22.

[0029] As shown in Figures 1 and 2, water-cooling assembly 1 includes an inner water jacket 26, an outer water jacket 27, and a stator water channel 2. The inner water jacket 26 is connected to the stator core 22 in the stator assembly. Flanges 3 are connected between the axial ends of the inner and outer water jackets 26, 27 and the end cover assembly. The stator water channel 2 is located between the inner and outer water jackets 26, 27, and flanges 3. Water channel ribs are uniformly distributed within the stator water channel 2. The length of the water channel ribs is shorter than that of the outer and inner water jackets 27, 26. The water channel ribs include water channel rib 1 4 and water channel rib 2 5, which are respectively connected to the flanges 3 on both sides. Water channel rib 1 4 and water channel rib 2 5 are spaced apart and form a round-trip water channel for the stator water channel 2. A water retaining ring 9 is provided at the end where the water channel ribs connect to the flange 3. The round-trip water channel can make the temperature at both ends of the motor stator more uniform and reduce the hot spot temperature of the motor.

[0030] The water-cooling system also includes a second water-cooling assembly located within the end cap assembly. A cooling chamber 6 is formed between the end cap assembly, flange 3, stator assembly, rotor assembly, and central shaft 1. The second water-cooling assembly includes an isolation plate 7 and an end cap water channel 8. The isolation plate 7 is mounted on the end cap assembly and located within the cooling chamber 6. The end cap water channel 8 is formed between the isolation plate 7 and the end cap assembly. The end cap assembly houses a bearing, and the end cap water channel 8 specifically cools the bearing, helping to reduce bearing temperature. This also increases the water-cooling heat dissipation area of ​​the motor, helping to lower the motor's internal temperature.

[0031] As shown in Figure 1, the end cap assembly includes a non-drive end cap assembly 10 and a drive end cap assembly 11. The non-drive end cap assembly 10 includes an end cap 16, a ball bearing 17, and an oil seal 18. The ball bearing 17 is located between the end cap 16 and the central shaft 1. The oil seal 18 is located between the end cap 16 and the central shaft 1 and is located outside the ball bearing 17. The drive end cap assembly 11 includes an end cap 2 19, a cylindrical bearing 20, and an oil seal 21. The cylindrical bearing 20 is located between the end cap 2 19 and the central shaft 1. The oil seal 21 is located between the end cap 2 19 and the central shaft 1 and is located outside the cylindrical bearing 20. The cooling cavity 6 on one side of the non-driving end cover assembly 10 is formed between the end cover 1 16, the flange 3 on one side of the non-driving end cover assembly 10, the stator core 22, the rotor core 24 and the central rotating shaft 1, and the cooling cavity 6 on one side of the driving end cover assembly 11 is formed between the end cover 2 19, the flange 3 on one side of the driving end cover assembly 11, the stator core 22, the rotor core 24 and the central rotating shaft 1.

[0032] The air cooling system includes a fan located on the pressure ring, which is located in the cooling chamber 6 and on the inner side of the isolation plate 7. As shown in Figure 1, the pressure ring located on the side of the non-driving end cover assembly 10 and the pressure ring located on the side of the driving end cover assembly 11 are respectively the first pressure ring 12 and the second pressure ring 13. The fan on the first pressure ring 12 and the fan on the second pressure ring 13 are respectively the first fan 14 and the second fan 15. The first pressure ring 12 and the second pressure ring 13 are respectively set according to the shape of the central shaft 1. The shape specifications of the first pressure ring 12 and the second pressure ring 13 are different. The first fan 14 and the second fan 15 are the same or different, and are specifically set according to actual needs. The first fan 14 and the second fan 15 are the blade structures set at the end of the motor rotor core 24. The hot air inside the motor is stirred by the rotation of the rotor core 24, so that the internal temperature of the motor is more uniform, which is conducive to reducing the hot spot temperature of the motor. At the same time, the motor has a simple structure and a small size, and is suitable for the built-in structure of the bogie axle box.

[0033] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0034] The above specific embodiments of the present invention do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A permanent magnet direct drive traction motor for being built inside a bogie axle box, characterized in that It includes a central rotating shaft (1), a rotor assembly, a stator assembly, and a cooling system. The rotor assembly is fixedly connected to the central rotating shaft (1), and the stator assembly is located outside the rotor assembly. An end cover assembly is connected to the central rotating shaft (1) and located outside the axial ends of the stator assembly and the rotor assembly. The cooling system includes an air-cooling system and a water-cooling system. The air-cooling system is arranged between the axial end of the rotor assembly and the end cover assembly. The water-cooling system includes a first water-cooling component connected to one end of the stator assembly away from the central rotating shaft (1), and the first water-cooling component is located between the end cover assemblies.

2. The permanent magnet direct drive traction motor built inside the bogie axle box according to claim 1, characterized in that, The first water-cooling component includes an inner water jacket (26), an outer water jacket (27), and a stator water channel (2). The inner water jacket (26) is connected to the stator assembly. Flanges (3) are connected between both ends of the inner water jacket (26) and the outer water jacket (27) and the end cover assembly. The stator water channel (2) is located between the inner water jacket (26), the outer water jacket (27), and the flange (3).

3. The permanent magnet direct drive traction motor built inside the bogie axle box according to claim 2, characterized in that, Water channel ribs are evenly distributed in the stator water channel (2), and the length of the water channel ribs is less than the lengths of the outer water jacket (27) and the inner water jacket (26). The water channel ribs include a first water channel rib (4) and a second water channel rib (5) respectively connected to the flanges (3) on both sides. The first water channel rib (4) and the second water channel rib (5) are arranged at intervals to form a reciprocating water channel in the stator water channel (2).

4. The permanent magnet direct drive traction motor for in-built bogie axle box according to claim 3, characterized in that, The water-cooling system further includes a second water-cooling component located at the end cover assembly. A cooling cavity (6) is formed between the end cover assembly, the flange (3), the stator assembly, the rotor assembly, and the central rotating shaft (1). The second water-cooling component includes a partition plate (7) and an end cover water channel (8). The partition plate (7) is arranged on the end cover assembly and located in the cooling cavity (6). The end cover water channel (8) is formed between the partition plate (7) and the end cover assembly.

5. The permanent magnet direct drive traction motor for in-built bogie axle box according to claim 4, characterized in that, A water retaining ring (9) is provided at the end of the water channel rib connected to the flange (3).

6. The permanent magnet direct drive traction motor for in-built bogie axle box according to claim 5, characterized in that, Pressing rings are provided at both axial ends of the rotor assembly. The air-cooling system includes a fan located on the pressing ring. The fan is located in the cooling cavity (6) and on the inner side of the partition plate (7).

7. The permanent magnet direct drive traction motor for in-built bogie axle box according to claim 6, characterized in that, The end cover assembly includes a non-drive end cover assembly (10) and a drive end cover assembly (11). The pressing rings located on one side of the non-drive end cover assembly (10) and on one side of the drive end cover assembly (11) are a first pressing ring (12) and a second pressing ring (13) respectively. The fans on the first pressing ring (12) and the second pressing ring (13) are a first fan (14) and a second fan (15) respectively. The first pressing ring (12) and the second pressing ring (13) are respectively arranged according to the shape of the central rotating shaft (1), and the shape specifications of the first pressing ring (12) and the second pressing ring (13) are different. The first fan (14) and the second fan (15) are the same or different.

8. The permanent magnet direct drive traction motor built inside the bogie axle box according to claim 7, characterized in that, The non-drive end cover assembly (10) includes an end cover one (16), a ball bearing (17), and a first oil seal (18). The ball bearing (17) is located between the end cover one (16) and the central rotating shaft (1). The first oil seal (18) is located between the end cover one (16) and the central rotating shaft (1) and on the outer side of the ball bearing (17).

9. The permanent magnet direct drive traction motor for in-built bogie axle box according to claim 8, characterized in that, The driving end cover assembly (11) includes a second end cover (19), a cylindrical bearing (20), and a second oil seal (21). The cylindrical bearing (20) is located between the second end cover (19) and the central rotating shaft (1), and the second oil seal (21) is located between the second end cover (19) and the central rotating shaft (1) and on the outer side of the cylindrical bearing (20).

10. The permanent magnet direct drive traction motor built inside the bogie axle box according to any one of claims 1-9, characterized in that, The stator assembly includes a stator core (22) and a stator winding (23). The stator core (22) is laminated from silicon steel sheets and is heat-shrunk into the first water-cooling assembly; the rotor assembly includes a rotor core (24) and a permanent magnet (25). The rotor core (24) is laminated from silicon steel sheets and is interference-fitted and heat-shrunk onto the central rotating shaft (1); the rotor core (24) is provided with a topological structure of a "U-shaped groove" and a "one-shaped groove", and the permanent magnet (25) is embedded in the "U-shaped groove" and the "one-shaped groove", and the permanent magnet (25) is located inside the rotor core (24).

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