Fully enclosed self-ventilated electric motor

Abstract

A fully enclosed self-ventilated electric motor comprises a stator, a rotor, a front end cover and a rear end cover. The rotor is arranged inside the stator, and the rotor comprises a rotor core, a rotor press ring, a rotating shaft, a front-end rotor interlayer and a rear-end rotor interlayer. The stator comprises a stator core, a stator winding and a stator press ring. The front end cover and the rear end cover are respectively arranged at the front end and the rear end of a power structure composed of the stator and the rotor. A through axial stator air duct is provided in the stator core, and a through inner rotor air duct is provided in the rotor. An air outlet and a front end cover ventilation duct are provided in the front end cover, and an air inlet and a rear end cover ventilation duct are provided in the rear end cover. The air inlet of the rear end cover, the rear end cover ventilation duct, the axial stator air duct and the front end cover ventilation duct form a first cooling air circuit, and the air inlet of the rear end cover, the inner rotor air duct and the air outlet of the front end cover form a second cooling air circuit. Neither the first cooling air circuit nor the second cooling air circuit is in communication with the stator winding. The fully enclosed self-ventilated electric motor of the present application has an excellent cooling effect.

Description

A fully enclosed self-ventilated motor Technical Field

[0001] The present application relates to the technical field of cooling of rail traction motors, and in particular to a fully enclosed self-ventilated motor. Background Art

[0002] In order to prevent metal powder generated by the friction between the wheels and rails during the operation of railway locomotives and brake shoe dust generated by the wear of brake shoes during braking from entering the motor and being adsorbed on the surface of the permanent magnet motor rotor, permanent magnet motors are usually required to adopt a fully enclosed structure.

[0003] Conventional fully enclosed, self-ventilated permanent magnet motors (PMMs) are cooled through stator ducts. During operation, cooling air generated by an external fan mounted on the rotor enters the stator duct through the non-drive-end cover and flows axially along the stator duct to the outlet on the drive-end cover or the intermediate cover. The air then exits the duct, removing heat from the motor. This conventional, fully enclosed, externally fanned, self-ventilated PMM motor dissipates heat solely through the stator duct (a single heat dissipation channel). This prevents effective heat dissipation within the motor, making the motor prone to becoming an isothermal body. Heat within the motor is conducted and radiated between various parts, leading to high temperatures at the stator coil ends, permanent magnets, and bearings. However, the temperature limits of the coils, bearings, and permanent magnets vary, limiting motor power gains, particularly those requiring high torque density, high power density, and compact design. Furthermore, permanent magnet motors currently used in rail vehicles often utilize high-temperature-resistant rare earth permanent magnet materials to prevent irreversible demagnetization of the rotor-mounted permanent magnets.

[0004] CN202309380U discloses a self-fan fully enclosed dual-circulation air-cooled motor structure, which, in addition to the conventional stator ventilation and cooling structure, is provided with a second cooling air path inside the motor. The principle of the second cooling air path is to install a ventilation fan on one side of the rotor core, bring the rotor heat to the stator through the internal circulating air, and then take the heat away through the first cooling air path. However, the second cooling air path only circulates inside the motor, and the heat inside the motor is not directly exchanged with the outside air for heat dissipation, which has limited cooling effect on the rotor and bearings.

[0005] CN102356534B discloses a fully enclosed main motor for vehicles. In addition to the conventional stator ventilation and cooling structure, a second cooling air duct is provided on the non-drive end bearing side. The principle of the second cooling air duct is to install a ventilation fan on the rotor core, suck in external air from the air inlet of the non-drive end bracket, and then discharge it from the air outlet of the non-drive end bracket to directly cool the non-drive end bearing and indirectly cool the rotor. However, the motor rotor temperature of this cooling scheme is still relatively high, and it is mainly used in asynchronous motors. When used in permanent magnet motors, the permanent magnets installed on the rotor are at risk of high-temperature demagnetization.

[0006] CN1848620B discloses a fully enclosed external fan type electric motor. In addition to the conventional stator ventilation and cooling structure, a second cooling air duct is set on the inner side of the rotor. The principle of the second cooling air duct is to install a ventilation fan (or a rotor-specific ventilation fan) on one side of the rotor, and let the cooling air enter from the air inlet of the non-drive end cover, flow through the ventilation duct that runs axially through the rotor iron core, and then merge into the first cooling air duct of the stator, and finally be discharged from the air outlet of the non-drive end. However, the rotor ventilation volume of the second cooling air duct of this cooling structure is limited, and the heat of the rotor cannot be effectively dissipated. In addition, the heat of the rotor is blown out through the stator ventilation duct, which reduces the heat dissipation efficiency of the stator.

[0007] In summary, the design of the existing patent adds a second cooling air path in addition to the aforementioned stator ventilation cooling air path. Specifically, a dedicated ventilation fan is installed on one side of the rotor core to transfer rotor heat to the stator core through internal circulating air, and then remove the heat through the stator core's first cooling air path. This added second cooling air path only transfers internal heat from the motor to the stator core, and does not directly exchange heat with the outside atmosphere. The cooling effect is limited, so the temperature inside the motor remains high. When used in permanent magnet motors, permanent magnets with higher temperature resistance still need to be used.

[0008] It can be seen that how to provide a cooling structure that is applicable to a fully enclosed motor and can achieve a better cooling effect on the internal structure of the motor is still a technical problem that needs to be solved urgently by those skilled in the art.

[0009] Summary of the Invention

[0010] In order to solve the above technical problems, the present invention provides a fully enclosed self-ventilated motor, which can not only efficiently ventilate and cool the stator, rotor, bearings and other parts, but also better adapt to the low-speed operation conditions of the vehicle by adjusting the amount of cooling air introduced from the outside. The cooling structure is simple and can be applied to asynchronous and permanent magnet traction motors.

[0011] The technical solutions provided by the present invention are as follows:

[0012] A fully enclosed self-ventilated motor, comprising a stator, a rotor, a front end cover and a rear end cover, wherein the rotor is arranged on the inner side of the stator, the rotor comprises a rotor core, a front end rotor pressure ring, a rear end rotor pressure ring, a rotating shaft, a front end rotor sandwich and a rear end rotor sandwich, wherein the front end rotor sandwich and the rear end rotor sandwich are respectively arranged at both ends of the rotor core, the stator comprises a stator core, a stator winding, a front end stator pressure ring and a rear end stator pressure ring, and the front end cover and the rear end cover are respectively arranged at the front end and the rear end of the power structure composed of the stator and the rotor. The stator core is provided with a through stator axial air duct, the rotor is provided with a through rotor inner air duct, the front end cover is provided with an air outlet and a front end cover ventilation duct, and the rear end cover is provided with an air inlet and a rear end cover ventilation duct; the air inlet of the rear end cover, the rear end cover ventilation duct, the stator axial air duct and the front end cover ventilation duct constitute a first cooling air path, the air inlet of the rear end cover, the rotor inner air duct and the air outlet of the front end cover constitute a second cooling air path, and both the first cooling air path and the second cooling air path are not connected to the stator winding.

[0013] Preferably, the fully enclosed self-ventilated motor further includes an external fan, which is located at the air inlet of the rear end cover and is mounted on the rear end shaft of the rotor core to rotate synchronously with the rotor, and an air inlet is provided on the structure of the external fan itself.

[0014] Preferably, a filter is provided at the air inlet end of the external fan.

[0015] Preferably, the fully enclosed self-ventilated motor also includes a heat exchanger, which is arranged on the outside of the stator and forms an external air duct together with the structure of the stator, and the front end stator pressure ring is provided with a first built-in ventilation duct, and the rear end stator pressure ring is provided with a second built-in ventilation duct for connecting the inside of the motor and the external air duct; the rotor is also provided with a through rotor external air duct, and the first built-in ventilation duct of the front end stator pressure ring, the rotor external air duct, the second built-in ventilation duct of the rear end stator pressure ring and the external air duct together constitute a third cooling air duct structure.

[0016] Preferably, a front ventilation cavity is left between the front end cover and the rotor core, and a rear ventilation cavity is left between the rear end cover and the rotor core. Both the front ventilation cavity and the rear ventilation cavity are located in the second cooling air path.

[0017] Preferably, a front end bearing is provided below the front end cover, and the front end bearing is arranged on one side of the front end ventilation cavity; a rear end bearing is provided below the rear end cover, and the rear end bearing is arranged on one side of the rear end ventilation cavity.

[0018] Preferably, the front end cover is provided with a front end cover annular boss A and a front end cover annular boss B, the front end cover annular boss B is located on the inner side of the front end cover annular boss A, a contact seal is provided between the front end cover annular boss A and the front end stator pressure ring, and a non-contact seal is provided between the front end cover annular boss B and the front end rotor interlayer, and the front end of the stator winding is in a sealed cavity formed by the front end cover annular boss A, the front end cover annular boss B, the stator core and the rotor core; the rear end cover is provided with a rear end cover annular boss A and a rear end cover annular boss B, the rear end cover annular boss B is located on the inner side of the rear end cover annular boss A, a contact seal is provided between the rear end cover annular boss A and the rear end stator pressure ring, and a non-contact seal is provided between the rear end cover annular boss B and the rear end rotor interlayer, and the rear end of the stator winding is in a sealed cavity formed by the rear end cover annular boss A, the rear end cover annular boss B, the stator core and the rotor core.

[0019] Preferably, the stator winding is located in a sealed cavity so that the stator winding is isolated from the outside.

[0020] Preferably, the front rotor interlayer and the rear rotor interlayer are both annular structures, and blades are provided on the front rotor interlayer and / or the rear rotor interlayer.

[0021] Preferably, the fully enclosed self-ventilated motor is suitable for use as an asynchronous or permanent magnet traction motor for rail vehicles.

[0022] This application has the following advantages over the prior art:

[0023] 1. The fully enclosed self-ventilated motor of the present application is designed with a first cooling air path consisting of an air inlet of the rear end cover, a rear end cover ventilation duct, a stator axial air duct, and a front end cover ventilation duct; and a second cooling air path consisting of an air inlet of the rear end cover, an inner rotor air duct, and an air outlet of the front end cover. The stator, rotor, and bearings are cooled simultaneously through the first cooling air path and the second cooling air path, and the ventilation and cooling structure is simple. In addition, by adjusting the amount of cooling air introduced from the outside, the motor can better adapt to the low-speed operating conditions of the vehicle, which is conducive to improving the power density and torque density indicators of the motor. Moreover, since neither the first cooling air path nor the second cooling air path is connected to the stator winding, the motor can be applied to traction motors for rail vehicles in harsh windy and sandy environments, and has high safety and versatility.

[0024] 2. In order to further dissipate the heat inside the motor more effectively into the outside air, the fully enclosed self-ventilated motor of the present application is provided with a third cooling air path structure in addition to the first cooling air path and the second cooling air path. The third cooling air path brings the heat inside the motor to the external air duct, and directly exchanges heat with the outside air through the heat exchanger, thereby greatly reducing the internal temperature of the motor.

[0025] 3. The fully enclosed self-ventilated motor of the present application is provided with a heat exchanger in the third cooling air path, which improves the heat exchange efficiency of the heat inside and outside the motor and effectively reduces the internal temperature of the motor. When applied to a permanent magnet motor, it can effectively reduce the temperature of the permanent magnet and improve reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] FIG1 is a schematic structural diagram of a fully enclosed self-ventilated motor in Example 1 of the present invention;

[0028] FIG2 is a schematic structural diagram of a fully enclosed self-ventilated motor in Example 2 of the present invention;

[0029] FIG3 is a schematic structural diagram of a fully enclosed self-ventilated motor in Example 3 of the present invention;

[0030] FIG4 is a schematic structural diagram of the external air duct in Example 2 of the present invention;

[0031] FIG5 is a schematic structural diagram of the external air duct in Example 3 of the present invention;

[0032] FIG6 is a schematic structural diagram of the external air duct in Example 2 of the present invention;

[0033] FIG7 is a schematic structural diagram of the external air duct in Example 2 of the present invention;

[0034] FIG8 is a schematic structural diagram of the rotor axial air duct in Example 2 of the present invention;

[0035] FIG9 is a schematic structural diagram of the rotor axial air duct in Example 2 of the present invention.

[0036] Reference numerals:

[0037] 1. Stator; 11. Stator core; 111. Stator axial air duct; 12. Stator winding; 13. Front stator pressure ring; 131. First built-in air duct; 14. Rear stator pressure ring; 141. Second built-in air duct; 2. Rotor; 21. Rotor core; 22. Front rotor pressure ring; 23. Rear rotor pressure ring; 211. Rotor inner air duct; 212. Rotor outer air duct; 24. Front rotor interlayer; 25. Rear rotor interlayer; 26. Rotating shaft; 3. Front cover; 31. Air outlet; 32. Front cover ventilation duct; 33. Front cover annular boss A; 34. Front cover annular boss B; 4. Rear cover; 41. Air inlet; 42. Rear cover ventilation duct; 43. Rear cover annular boss A; 44. Rear cover annular boss B; 5. External fan; 51. Filter; 52. External fan air inlet; 6. Front ventilation chamber; 7. Rear ventilation chamber; 8. Front bearing; 9. Rear bearing; 10. Heat exchanger; 101. External air duct. DETAILED DESCRIPTION

[0038] In order to help those skilled in the art better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of this application.

[0039] Example 1:

[0040] As shown in Figure 1, an embodiment of the present invention provides a fully enclosed self-ventilated motor, which is suitable for asynchronous or permanent magnet traction motors for rail vehicles, including a stator 1, a rotor 2, a front end cover 3, a rear end cover 4 and an external fan 5. The rotor 2 is arranged on the inner side of the stator 1, and the rotor 2 includes a rotor core 21, a front end rotor pressure ring 22, a rear end rotor pressure ring 23, a rotating shaft 26, a front end rotor interlayer 24 and a rear end rotor interlayer 25. The front end rotor interlayer 24 and the rear end rotor interlayer 25 are respectively arranged at the two ends of the rotor core 21. The stator 1 includes a stator core 11, a stator winding 12, a front end stator pressure ring 13, and a rear end stator pressure ring 14. The front end cover 3 and the rear end cover 4 are respectively arranged at the front end and the rear end of the power structure composed of the stator 1 and the rotor 2. The stator core 11 is provided with a through stator axial air duct 111, and the rotor core 21, the front end rotor pressure ring 22, and the rear end rotor pressure ring 23 are provided with a through rotor inner side air duct 211 and The rotor outer air duct 212 (rotor axial air duct), the rotor inner air duct 211 and the rotor outer air duct 212 can be of any shape, and the number of the rotor inner air duct 211 can be more than two. The front end cover 3 is provided with an air outlet 31 and a front end cover ventilation duct 32, and the rear end cover 4 is provided with an air inlet 41 and a rear end cover ventilation duct 42; the air inlet 41 of the rear end cover 4, the rear end cover ventilation duct 42, the stator axial air duct 111 and the front end cover ventilation duct 32 constitute a first cooling air path, and the air inlet 41 of the rear end cover 4, the rotor inner air duct 211 and the air outlet 31 of the front end cover 3 constitute a second cooling air path. Neither the first cooling air path nor the second cooling air path is connected to the stator winding 12; the external fan 5 is located at the air inlet 41 of the rear end cover 4 and is installed on the rear end shaft extension of the rotor core 21 and rotates synchronously with the rotor 2. The external fan 5 can use centrifugal blades or axial flow blades. The air inlet end of the external fan 5 is provided with a filter 51.

[0041] The fully enclosed, self-ventilated motor of this embodiment is structurally designed to include a first cooling air path consisting of the air inlet 41 of the rear end cover 4, the rear end cover ventilation duct 42, the stator axial air duct 111, and the front end cover ventilation duct 32; and a second cooling air path consisting of the air inlet 41 of the rear end cover 4, the rotor inner air duct 211, and the air outlet 31 of the front end cover 3. The stator 1, rotor 2, front end bearing 8, and rear end bearing 9 are cooled simultaneously through the first and second cooling air paths, resulting in a simple ventilation and cooling structure. Furthermore, by adjusting the amount of cooling air introduced from the outside, especially when increasing the amount of air flowing through the rotor 2, the motor's heat dissipation during low-speed vehicle operation is further enhanced. Furthermore, since neither the first nor the second cooling air path is connected to the stator winding 12, the motor can be used as a traction motor for rail vehicles in harsh windy and sandy environments, providing high safety and versatility.

[0042] In this embodiment, the cooling air introduced by the external fan 5 forms two parallel cooling air path structures to simultaneously cool the stator, rotor and bearings, thereby solving the problem of insufficient heat dissipation inside the motor, effectively improving the power density and torque density of the permanent magnet motor, and when applied to the permanent magnet motor to reduce the temperature of the rotor 2, permanent magnet materials with low temperature resistance can be used.

[0043] In this embodiment, a front ventilation cavity 6 is left between the front cover 3 and the rotor core 21, and a rear ventilation cavity 7 is left between the rear cover 4 and the rotor core 21. Both the front ventilation cavity 6 and the rear ventilation cavity 7 are located in the second cooling air path.

[0044] The specific cooling process of the fully enclosed self-ventilated motor of this embodiment is as follows:

[0045] (1) The external fan 5 mounted on the rear end shaft extension of the rotor core 21 draws in external cooling air from the external fan air inlet 52 through centrifugal blades. A portion of the air flows through the ventilation duct 42 of the rear end cover 4 and the stator axial ventilation duct 111 in sequence, and is then discharged through the ventilation duct 32 of the front end cover. During the cooling air flow, the cooling air removes the heat generated by the stator core 11 and the stator winding 12.

[0046] (2) The external fan 5 installed on the rear end shaft extension of the rotor core 21 draws in external cooling air from the air inlet through centrifugal blades, and another part of the air flows through the air inlet 41 of the rear end cover 4, the rear end ventilation cavity 7, the rotor inner side air duct 211, the front end ventilation cavity 6, and then is discharged through the air outlet 31 of the front end cover 3. During the flow of the cooling air, the external cooling air can take away the heat radiated from the stator winding 12 to the end cover, and the heat generated by the rotor 2 and the front end bearing 8 and the rear end bearing 9.

[0047] In this embodiment, a front end bearing 8 is provided below the front end cover 3, and the front end bearing 8 is arranged on one side of the front end ventilation cavity 6; a rear end bearing 9 is provided below the rear end cover 4, and the rear end bearing 9 is arranged on one side of the rear end ventilation cavity 7.

[0048] In this embodiment, the front end cover 3 is provided with a front end cover annular boss A33 and a front end cover annular boss B34. The front end cover annular boss B34 is located on the inner side of the front end cover annular boss A33. A contact seal is provided between the front end cover annular boss A33 and the front end stator pressure ring 13. A non-contact seal is provided between the front end cover annular boss B34 and the front end rotor interlayer 24. The front end of the stator winding 12 is in the seal formed by the front end cover annular boss A33, the front end cover annular boss B34, the stator core 11 and the rotor core 21. The rear end cover 4 is provided with a rear end cover annular boss A43 and a rear end cover annular boss B44. The rear end cover annular boss B44 is located on the inner side of the rear end cover annular boss A43. A contact seal is provided between the rear end cover annular boss A43 and the rear end stator pressure ring 14. A non-contact seal is provided between the rear end cover annular boss B44 and the rear end rotor interlayer 25. The rear end of the stator winding 12 is located in the sealed cavity formed by the rear end cover annular boss A43, the rear end cover annular boss B44, the stator core 11 and the rotor core 21. The annular bosses of the front end cover annular boss A33, the front end cover annular boss B34, the rear end cover annular boss A43 and the rear end cover annular boss B44 can be formed by casting the end cover itself or by other connections such as welding, interference fit, and bolting.

[0049] In this embodiment, the front end rotor interlayer 24 and the rear end rotor interlayer 25 are both annular structures. Blades are provided on the front end rotor interlayer 24 and / or the rear end rotor interlayer 25. The blades can be blades of an air circulation fan. The front end rotor interlayer 24 and the rear end rotor interlayer 25 can be fixed to the front end rotor pressure ring 22 and the rear end rotor pressure ring 23 by welding, interference fit, bolt connection or other means.

[0050] Example 2:

[0051] As shown in FIG2 , the difference between this embodiment 2 and embodiment 1 is that the fully enclosed self-ventilated motor further includes a heat exchanger 10. The heat exchanger 10 can be a simple arc-shaped pull plate (as shown in FIG4 and FIG5 ), or a finned structure to improve heat exchange efficiency (as shown in FIG6 and FIG7 ). The material can be steel or copper or aluminum with better thermal conductivity. The heat exchanger is fixed to the outside of the stator 1 by welding or bolting. The number can be single or multiple, and together with the structure of the stator, an external air duct 101 is formed, and the front end stator pressure ring 13 is provided with a first built-in ventilation duct 131, and the rear end stator pressure ring 14 is provided with a second built-in ventilation duct 141 for connecting the inside of the motor and the external air duct 101; the rotor core 21. The front rotor pressing ring 22 and the rear rotor pressing ring 23 are also provided with a through rotor inner duct 211 and a rotor outer duct 212 (rotor axial duct). The first built-in ventilation duct 131, the rotor outer duct 212, the second built-in ventilation duct 141 and the outer duct 101 together constitute a third cooling air duct structure. The rotor axial duct includes the rotor inner duct 211 and the rotor outer duct 212. The rotor inner duct 211 and the rotor outer duct 212 can be separate ducts formed by different pitch circles (as shown in Figure 8), or multiple ducts on the same pitch circle can be used as inner ducts and outer ducts respectively (as shown in Figure 9). The ducts can be of any shape, and the circumferential number can be odd or even. The remaining structure is the same as that of Example 1.

[0052] Example 3:

[0053] As shown in FIG3 , the difference between this embodiment 3 and embodiment 2 is that the first and third cooling air passages are retained, the second cooling air passage is cancelled, and the rest of the structure is the same as that of embodiment 2.

[0054] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fully enclosed self-ventilated motor, comprising a stator (1), a rotor (2), a front end cover (3) and a rear end cover (4). The rotor (2) is arranged inside the stator (1). The rotor (2) includes a rotor core (21), a front rotor clamping ring (22), a rear rotor clamping ring (23), a rotating shaft (26), a front rotor sandwich layer (24) and a rear rotor sandwich layer (25). The front rotor sandwich layer (24) and the rear rotor sandwich layer (25) are respectively arranged at both ends of the rotor core (21). The stator (1) includes a stator core (11), a stator winding (12), a front stator clamping ring (13) and a rear stator clamping ring (14). The front end cover (3) and the rear end cover (4) are respectively arranged at the front end and the rear end of the power structure composed of the stator (1) and the rotor (2). It is characterized in that, The stator core (11) is provided with a through stator axial air duct (111), the rotor (2) is provided with a through inner rotor air duct (211), the front end cover (3) is provided with an air outlet (31) and a front end cover air duct (32), and the rear end cover (4) is provided with an air inlet (41) and a rear end cover air duct (42); the air inlet (41) of the rear end cover (4), the rear end cover air duct (42), the stator axial air duct (111) and the front end cover air duct (32) form a first cooling air path, and the air inlet (41) of the rear end cover (4), the inner rotor air duct (211) and the air outlet (31) of the front end cover (3) form a second cooling air path. Neither the first cooling air path nor the second cooling air path is communicated with the stator winding (12).

2. The fully enclosed self-ventilated motor according to claim 1, characterized in that, An external fan (5) is further included. The external fan (5) is located at the air inlet (41) of the rear end cover (4) and is installed on the rear end shaft extension of the rotor core (21) to rotate synchronously with the rotor (2).

3. The fully enclosed self-ventilated motor according to claim 2, characterized in that, A filter screen (51) is provided at the air inlet end of the external fan (5).

4. The fully enclosed self-ventilated motor according to claim 1, characterized in that, A heat exchanger (10) is further included. The heat exchanger is arranged outside the stator and jointly forms an external air duct (101) with the structure of the stator. The front stator retaining ring (13) is provided with a first internal air duct (131), and the rear stator retaining ring (14) is provided with a second internal air duct (141) for communicating the inside of the motor and the external air duct (101); a through outer rotor air duct (212) is further provided on the rotor (2). The first internal air duct (131) of the front stator retaining ring (13), the outer rotor air duct (212), the second internal air duct (141) of the rear stator retaining ring (14) and the external air duct (101) jointly form a third cooling air path structure.

5. The fully enclosed self-ventilated motor according to any one of claims 1-4, characterized in that, A front ventilation cavity (6) is left between the front end cover (3) and the rotor core (21), and a rear ventilation cavity (7) is left between the rear end cover (4) and the rotor core (21). Both the front ventilation cavity (6) and the rear ventilation cavity (7) are in the second cooling air path.

6. The fully enclosed self-ventilated motor according to claim 5, characterized in that, A front bearing (8) is provided below the front end cover (3), and the front bearing (8) is arranged on one side of the front ventilation cavity (6); a rear bearing (9) is provided below the rear end cover (4), and the rear bearing (9) is arranged on one side of the rear ventilation cavity (7).

7. The fully enclosed self-ventilated motor according to any one of claims 1-4, characterized in that, The front end cover (3) is provided with a front end cover annular boss A (33) and a front end cover annular boss B (34). The front end cover annular boss B (34) is located inside the front end cover annular boss A (33). A contact seal is provided between the front end cover annular boss A (33) and the front stator retaining ring (13). A non-contact seal is provided between the front end cover annular boss B (34) and the front rotor sandwich layer (24). The front end of the stator winding (12) is located in a sealed cavity formed by the front end cover annular boss A (33), the front end cover annular boss B (34), the stator core (11) and the rotor core (21). The rear end cover (4) is provided with a rear end cover annular boss A (43) and a rear end cover annular boss B (44). The rear end cover annular boss B (44) is located inside the rear end cover annular boss A (43). A contact seal is provided between the rear end cover annular boss A (43) and the rear stator retaining ring (14). A non-contact seal is provided between the rear end cover annular boss B (44) and the rear rotor sandwich layer (25). The rear end of the stator winding (12) is located in a sealed cavity formed by the rear end cover annular boss A (43), the rear end cover annular boss B (44), the stator core (11) and the rotor core (21).

8. The fully enclosed self-ventilated motor according to claim 7, characterized in that, The stator winding (12) is located in the sealed cavity, separating the stator winding (12) from the outside.

9. The fully enclosed self-ventilated motor according to any one of claims 1-4, characterized in that, Both the front rotor sandwich layer (24) and the rear rotor sandwich layer (25) are annular structures, and blades are provided on the front rotor sandwich layer (24) and / or the rear rotor sandwich layer (25).

10. The fully enclosed self-ventilated motor according to any one of claims 1-4, characterized in that, The fully enclosed self-ventilated motor is applicable to asynchronous or permanent magnet traction motors for rail vehicles.

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