CN117879257A - Motor air cooling system - Google Patents

Abstract

The present invention relates to the field of motor cooling technology, and in particular to a motor air cooling system, which aims to solve the problems of low cooling efficiency, insufficient reliability, and high manufacturing and use costs for low-speed motors in the existing motor cooling system. The present invention includes a motor shaft, a fan and a transmission wheel group; the transmission wheel group includes an inner transmission wheel and an outer transmission wheel, the inner transmission wheel and the outer transmission wheel are coaxially arranged, the inner transmission wheel is sleeved on the motor shaft and connected to the motor shaft, and the outer transmission wheel is connected to the fan; the inner transmission wheel rotates under the drive of the motor shaft to drive the outer transmission wheel to rotate, and then the outer transmission wheel drives the fan to rotate so that the speed of the fan is higher than the motor shaft. The speed at which the motor shaft of the low-speed motor drives the fan to rotate is increased by the transmission wheel group, so that the fan generates sufficient air volume and air pressure to dissipate heat from the heat-generating components, thereby improving the cooling efficiency, and at the same time, no new mechanism is introduced, thereby improving the reliability of operation and reducing the manufacturing and use costs of the motor.

Description

Motor air cooling system

Technical Field

The present invention relates to the technical field of motor cooling, and in particular to a motor air cooling system.

Background technique

Air-cooled motors are widely used in renewable energy power generation, ship propulsion, ore mining and other fields due to their simple structure, low maintenance cost and reliable operation. The commonly used air-cooling structure of motors is to set the fan impeller at the protruding end of the shaft. The airflow is formed by the rotation of the fan impeller and the air pressure is increased to promote the air flow inside or around the motor to achieve the effect of cooling the motor. As the power of the motor continues to increase, the heat dissipation requirements are further improved. The coaxial fan of the low-speed motor has a low speed, and the wind pressure and air volume generated by the fan impeller are relatively low, resulting in a small circulating air volume and low wind speed in the cooling system. The cooling efficiency is also reduced, making it difficult to meet the heat dissipation requirements of the motor, which poses a safety risk to the long-term safe and reliable operation of the motor.

Liquid cooling methods such as water cooling and oil cooling can effectively improve the cooling efficiency of low-speed motors, but the structure of the liquid cooling system is relatively complex compared to the air cooling system, its operating reliability is low, and there is a risk of leakage. The air cooling method that uses a variable speed transmission mechanism or an external motor to drive the fan can obtain a higher impeller speed and improve the cooling efficiency of the motor. However, the introduction of new devices and structural components will increase the size of the motor, reduce the operating reliability, and also increase the cost of the motor. In summary, the existing motor cooling system has problems such as low cooling efficiency, insufficient reliability, and high manufacturing and use costs for low-speed motors.

Summary of the invention

The object of the present invention is to provide a motor air cooling system to solve the problems of low cooling efficiency, insufficient reliability, and high manufacturing and use costs for low-speed motors in existing motor cooling systems.

In order to solve the above technical problems, the technical solution provided by the present invention is:

A motor air cooling system comprises a motor shaft, a fan and a transmission wheel assembly;

The transmission wheel group includes an inner transmission wheel and an outer transmission wheel, the inner transmission wheel and the outer transmission wheel are coaxially arranged, the inner transmission wheel is sleeved on the motor shaft and connected to the motor shaft, and the outer transmission wheel is connected to the fan;

The inner transmission wheel rotates under the drive of the motor shaft to drive the outer transmission wheel to rotate, and then the outer transmission wheel drives the fan to rotate so that the rotation speed of the fan is higher than that of the motor shaft.

Furthermore, the inner transmission wheel includes a first magnet and a first ring body, the first magnet is mounted on the first ring body; a plurality of the first magnets are evenly distributed around the axis of the first ring body;

The outer transmission wheel includes a second magnet and a second ring body, wherein the second magnet is mounted on the second ring body; a plurality of the second magnets are evenly distributed around the axis of the second ring body.

Furthermore, the number of the first magnets is greater than the number of the second magnets, and the speed ratio of the inner transmission wheel to the outer transmission wheel is equal to the ratio of the number of the second magnets to the number of the first magnets.

Furthermore, the magnetic poles of the first magnet are distributed along the radial direction of the first ring body, and the magnetic poles of the second magnet are distributed along the radial direction of the second ring body; the magnetic poles of adjacent first magnets are in opposite directions, and the magnetic poles of adjacent second magnets are in opposite directions.

Furthermore, the transmission wheel assembly also includes a magnetic adjustment ring, which is sleeved on the inner transmission wheel and arranged between the inner transmission wheel and the outer transmission wheel; the magnetic adjustment ring includes ferromagnetic material and non-ferromagnetic material arranged at intervals.

Furthermore, the motor air cooling system also includes a casing and a rotor core and a stator core disposed in the casing, wherein the rotor core is inserted into the stator core;

The rotor core, the stator core, the fan and the housing form a first circulation passage; the first circulation passage comprises an air inlet passage, the fan, an axial ventilation passage, a radial ventilation passage, a converging passage and a return air passage which are connected in sequence;

The air inlet channel is arranged at one end of the fan air inlet and is connected with the air inlet of the casing; the rotor core is provided with the axial ventilation channel extending along its own axial direction; the radial ventilation channel extends along the radial direction of the rotor core and the stator core and passes through the rotor core and the stator core; the gap between the casing and the stator core extending along the axial direction of the stator core forms the confluence channel; the return air channel is connected with the air outlet on the casing to discharge air out of the casing.

Further, the radial ventilation channel includes a rotor radial channel and a stator radial channel;

The rotor core is divided into multiple sections along its own axis direction, and the gaps between the sections form the rotor radial channel;

The stator core is divided into multiple sections along its own axis direction, and the gaps between the sections form the stator radial channels.

Furthermore, the rotor core, the stator core, the fan and the housing form a second circulation passage; the second circulation passage includes the air inlet passage, the fan, the axial ventilation passage, the end ventilation passage, the converging passage and the return air passage which are connected in sequence;

The stator core and the rotor core form the end surface ventilation channel with the casing at one end away from the air inlet channel.

Furthermore, the motor air cooling system also includes a wind shield, which is connected to the casing and is used to separate the return air channel and the rotor radial channel.

Furthermore, the motor air cooling system also includes a heat exchanger; the heat exchanger is connected to the air outlet and the air inlet of the casing;

Driven by the fan, air flows along the first circulation path and the second circulation path; the air in the heat exchanger enters the air inlet channel from the air inlet of the casing and returns to the heat exchanger from the air outlet of the casing through the return air channel.

Based on the above technical solutions, the technical effects that can be achieved by the present invention are:

The motor air cooling system provided by the present invention comprises a motor shaft, a fan and a transmission wheel group; the transmission wheel group comprises an inner transmission wheel and an outer transmission wheel, the inner transmission wheel and the outer transmission wheel are coaxially arranged, the inner transmission wheel is sleeved on the motor shaft and connected to the motor shaft, and the outer transmission wheel is connected to the fan; the inner transmission wheel rotates under the drive of the motor shaft to drive the outer transmission wheel to rotate, and then the outer transmission wheel drives the fan to rotate so that the rotation speed of the fan is higher than that of the motor shaft.

The motor air cooling system provided by the present invention increases the speed of the fan driven by the motor shaft of the low-speed motor through the transmission wheel group, so that the fan generates sufficient air volume and air pressure to dissipate heat from the heat-generating components, improves the cooling efficiency, and ensures the long-term safe and reliable operation of the motor. At the same time, no new mechanism is introduced, which will not increase the size of the motor and make the structure complicated, further ensuring the reliability of operation, and no additional power is required to drive the fan, reducing the manufacturing and use costs of the motor.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG1 is a schematic structural diagram of a motor air cooling system provided by an embodiment of the present invention;

Figure 2 is a schematic diagram of the structure of the rotor and stator;

FIG3 is a schematic diagram of the structure of a transmission wheel set;

FIG4 is a schematic diagram of the structure of an electrically excited rotor;

FIG5 is a schematic diagram of the structure of a permanent magnet excitation rotor.

Icons: 100-motor shaft; 200-fan; 300-drive wheel assembly; 400-casing; 500-rotor core; 600-stator core; 700-wind shield; 800-heat exchanger; 900-stator winding; 1000-rotor winding; 1100-magnet; 310-inner drive wheel; 320-outer drive wheel; 330-magnetic adjustment ring; 311-first magnet; 312-first ring body; 321-second magnet; 322-second ring body; 910-stator left end winding; 920-stator slot inner winding; 930-stator right end winding; 101-air inlet channel; 102-axial ventilation channel; 103-radial ventilation channel; 104-convergence channel; 105-return air channel; 201-end face ventilation channel.

Detailed ways

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

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

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

Existing motor cooling systems have problems such as low cooling efficiency, insufficient reliability, and high manufacturing and use costs for low-speed motors.

In view of this, the present invention provides a motor air cooling system provided by the present invention, including a motor shaft 100, a fan 200 and a transmission wheel group 300; the transmission wheel group 300 includes an inner transmission wheel 310 and an outer transmission wheel 320, the inner transmission wheel 310 and the outer transmission wheel 320 are coaxially arranged, the inner transmission wheel 310 is sleeved on the motor shaft 100 and connected to the motor shaft 100, and the outer transmission wheel 320 is connected to the fan 200; the inner transmission wheel 310 rotates under the drive of the motor shaft 100 to drive the outer transmission wheel 320 to rotate, and then the outer transmission wheel 320 drives the fan 200 to rotate so that the rotation speed of the fan 200 is higher than that of the motor shaft 100.

The motor air cooling system provided by the present invention increases the speed at which the motor shaft 100 of the low-speed motor drives the fan 200 to rotate through the transmission wheel group 300, so that the fan 200 generates sufficient air volume and air pressure to dissipate heat from the heat-generating components, thereby improving the cooling efficiency and ensuring the long-term safe and reliable operation of the motor. At the same time, no new mechanism is introduced, which will not increase the size of the motor or complicate the structure, further ensuring the reliability of operation, and no additional power is required to drive the fan 200, thereby reducing the manufacturing and use costs of the motor.

The structure and shape of the motor air cooling system provided in this embodiment are described in detail below in conjunction with FIG. 1 to FIG. 5 :

The motor air cooling system provided in this embodiment includes a motor shaft 100, a fan 200, a transmission wheel group 300, a casing 400, a rotor core 500, a stator core 600, a wind shield 700, a heat exchanger 800, a stator winding 900 and a rotor winding 1000, as shown in Figure 1, and forms a first circulation path and a second circulation path.

Specifically, the motor shaft 100 drives the fan 200 to work through the transmission wheel group 300, the rotor core 500 and the rotor winding 1000 constitute the rotor, and the stator core 600 and the stator winding 900 constitute the stator, as shown in Figure 2; the rotor core 500 is mounted on the motor shaft 100 and connected to the motor shaft 100, and the rotor is inserted into the stator; the wind shield 700 is installed on the casing 400.

The first circulation passage includes an air inlet passage 101, a fan 200, an axial ventilation passage 102, a radial ventilation passage 103, a converging passage 104, a return air passage 105 and a heat exchanger 800 which are connected in sequence. As shown in FIG1 , the air inlet passage 101 is arranged at one end of the air inlet of the fan 200 and is connected to the air inlet of the housing 400, that is, one end of the air inlet passage 101 is connected to the air inlet of the housing 400, and the other end is connected to the air inlet end of the fan 200; the rotor core 500 is provided with an axial ventilation passage 102 extending along its own axial direction. 02; radial ventilation channel 103 extends along the radial direction of rotor core 500 and stator core 600 and passes through rotor core 500 and stator core 600; the gap between housing 400 and stator core 600 extending along the axial direction of stator core 600 forms confluence channel 104; return air channel 105 is connected with the air outlet on housing 400 to discharge air out of housing 400 and enter heat exchanger 800, the outlet of heat exchanger 800 is connected with the air inlet of housing 400, and the inlet of heat exchanger 800 is connected with the air outlet of housing 400. Heat exchanger 800 is installed in housing 400, and the air is cooled by heat exchanger 800 to ensure cooling effect, while ensuring the formation of a closed passage to prevent impurities from entering the motor, so as to ensure safe and stable operation of the motor.

In this embodiment, the wind shield 700 is used to separate the return air channel 105 and the rotor radial channel to ensure smooth air circulation, so that the air in the return air channel 105 flows into the heat exchanger 800 through the air outlet of the housing 400, thereby preventing the air in the return air channel 105 from entering the rotor radial channel without being cooled, thereby preventing the air from being turbulent and causing a decrease in cooling efficiency. That is, the wind shield 700 ensures a one-way flow in the circulation channel to ensure a cooling effect.

In this embodiment, the second circulation passage includes an air inlet passage 101, a fan 200, an axial ventilation passage 102, an end ventilation passage 201, a converging passage 104 and a return air passage 105 which are connected in sequence; the stator core 600 and the rotor core 500 form an end ventilation passage 201 with the housing 400 at one end away from the air inlet passage 101. That is, except for the radial ventilation passage 103 and the end ventilation passage 201, the first circulation passage and the other passages of the second circulation passage are shared, and the air in the end ventilation passage 201 flows along the radial direction of the rotor core 500.

In this embodiment, the radial ventilation channel 103 includes a rotor radial channel and a stator radial channel. Specifically, the rotor core 500 is divided into multiple sections along its own axis direction, and the gaps between the sections form the rotor radial channel, as shown in Figures 4 and 5; the stator core 600 is divided into multiple sections along its own axis direction, and the gaps between the sections form the stator radial channel, so that the air can fully contact the heat-generating components, thereby improving the cooling effect.

The motor air cooling system provided in this embodiment uses the transmission wheel assembly 300 to enable the motor shaft 100 to drive the fan 200 to operate and enable the fan 200 to obtain a higher rotation speed, so that the fan 200 generates sufficient wind pressure and air volume to cool the heat-generating components. At the same time, the first circulation path and the second circulation path are combined to allow the air to fully contact the heat-generating components and fully cooperate with the fan 200, thereby performing reliable and efficient cooling. In addition, since the radial ventilation channel 103 flows along the radial direction of the rotor core 500, when the air enters the converging channel 104 through the radial ventilation channel 103, it will be blocked by the inner wall of the housing 400 and will flow to both ends of the converging channel 104, and will not flow only to the return air channel 105, thereby causing airflow chaos, resulting in non-unidirectional flow of air, affecting the efficient and stable circulation of air, resulting in the failure to take away the heat in time, and reducing the cooling effect; while the end face ventilation channel 201 in the second circulation path solves this problem, the air flows along the end face ventilation channel 201, and enters the converging channel 104 under the guidance of the inner wall of the housing 400, and then carries the air flowing out of the radial ventilation channel 103 into the return air channel 105, ensuring the unidirectional flow of air, making the air circulate stably and smoothly, and improving the cooling effect. That is, through the cooperation of the first circulation path and the second circulation path, it is ensured that the air circulates stably and smoothly under the drive of the fan 200, and the stable and reliable cooling effect is ensured.

In this embodiment, the stator winding 900 can be divided into a stator left end winding 910, a stator slot inner winding 920 and a stator right end winding 930 along the axial direction, as shown in FIG. 2 .

In this embodiment, the rotor can be set to an electrically excited or permanently excited structure, as shown in FIG. 4 . The electrically excited rotor includes a rotor core 500 and a rotor winding 1000 , and the permanently excited rotor includes a rotor core 500 and a magnet 1100 , as shown in FIG. 5 .

In this embodiment, the fan 200 includes an air inlet pipe, an impeller, and an exhaust pipe. When the impeller rotates at a high speed, cold air enters the fan 200 through the air inlet pipe, rotates with the fan 200, and is thrown into the diffuser under the centrifugal action of the impeller. After continuous compression, it flows out of the exhaust pipe at a faster flow rate and then flows into the rotor core 500 through the exhaust pipe.

In an optional solution of this embodiment, the transmission wheel assembly 300 includes an inner transmission wheel 310, an outer transmission wheel 320 and a magnetic adjustment ring 330, as shown in Figure 3. The inner transmission wheel 310, the magnetic adjustment ring 330 and the outer transmission wheel 320 are coaxially arranged, the inner transmission wheel 310 is sleeved on the motor shaft 100 and connected to the motor shaft 100, the magnetic adjustment ring 330 is sleeved on the inner transmission wheel 310, and the outer transmission wheel 320 is sleeved on the magnetic adjustment ring 330 and connected to the impeller of the fan 200.

Specifically, the inner transmission wheel 310 includes a first magnet 311 and a first ring body 312, the first magnet 311 is installed on the first ring body 312, and a plurality of first magnets 311 are evenly distributed around the axis of the first ring body 312 to form a magnetic ring; the outer transmission wheel 320 includes a second magnet 321 and a second ring body 322, the second magnet 321 is installed on the second ring body 322; a plurality of second magnets 321 are evenly distributed around the axis of the second ring body 322 to form a magnetic ring. The magnetic poles of the first magnet 311 are distributed along the radial direction of the first ring body 312, and the magnetic poles of the second magnet 321 are distributed along the radial direction of the second ring body 322; the magnetic poles of adjacent first magnets 311 are in opposite directions, and the magnetic poles of adjacent second magnets 321 are in opposite directions, so that the inner transmission wheel 310 drives the outer transmission wheel 320 to rotate through the continuously changing magnetic field.

In this embodiment, the speed ratio of the inner transmission wheel 310 to the outer transmission wheel 320 is equal to the ratio of the number of the second magnets 321 to the number of the first magnets 311, and the number of the first magnets 311 is greater than the number of the second magnets 321 to ensure the effect of increasing the speed of the fan 200. The inner transmission wheel 310 rotates under the drive of the motor shaft 100 to drive the outer transmission wheel 320 to rotate, and then the outer transmission wheel 320 drives the fan 200 to rotate so that the speed of the fan 200 is higher than the speed of the motor shaft 100.

In this embodiment, the magnetic adjustment ring 330 does not rotate, and is made of ferromagnetic material and non-ferromagnetic material arranged at intervals for magnetic conduction, thereby ensuring that a stable torque is generated between the inner transmission wheel 310 and the outer transmission wheel 320, and ensuring that the inner transmission wheel 310 drives the outer transmission wheel 320 to rotate. When the inner transmission wheel 310 rotates, the magnetic field generated rotates, and then drives the outer transmission wheel 320 to rotate at a higher speed under the action of the magnetic force.

Driven by the fan 200, the air flows along the first circulation path and the second circulation path; the air in the heat exchanger 800 enters the air inlet channel 101 from the air inlet of the housing 400 and returns to the heat exchanger 800 from the air outlet of the housing 400 through the return air channel 105.

In the optional scheme of this embodiment, the transmission wheel group 300 can be set as a gear, the driving wheel is mounted on the motor shaft 100 and connected to the motor shaft 100, and the driven wheel is connected to the fan 200. Since the fan 200 is coaxially arranged with the motor shaft 100, at least one set of gears is required for torque transmission and speed change. This set of gears includes a first gear and a second gear, which are coaxially arranged and have the same rotation speed, that is, the two are fixedly connected by an axis. The driven wheel drives the first gear, and the second gear drives the fan 200 to rotate. In contrast, this structure has many parts, complex transmission, large space occupation and poor integration, and requires lubrication, and has high manufacturing, use and maintenance costs. The magnetic connection method can achieve contactless transmission, does not require lubrication, and has a simple structure and small space occupation.

The working process of the motor air cooling system provided in this embodiment is as follows:

First circulation path: driven by the fan 200, the cold air enters the air inlet channel 101 from the heat exchanger 800 through the air inlet of the casing 400. After passing through the fan 200, the cold air enters the axial ventilation channel 102 and flows along the radial ventilation channel 103, first passing through the rotor radial channel and then passing through the stator radial channel. The cold air undergoes convective heat exchange with the stator core 600, the winding 920 in the stator slot, the rotor core 500, and the rotor winding 1000, thereby taking away the heat, and then flows into the converging ventilation duct; finally, it flows toward the winding 910 at the left end of the stator, flows through the air outlet of the casing 400 to the heat exchanger 800 for cooling, and is transformed back into cold air to participate in the next round of circulation.

Second circulation path: On the basis of the first circulation path, after the cold air enters the axial ventilation path 102, it flows to the end ventilation path 201 along the direction from the stator left end winding 910 to the stator right end winding 930, and enters the converging path 104 under the guidance of the wind pressure and the inner wall of the housing 400 to merge with the air flowing out of the radial ventilation path 103, and then enters the return air path 105. It should be noted that the second circulation path can cool the rotor core 500, and cool the rotor winding 1000, the stator left end winding 910 and the stator right end winding 930.

That is, after the cold air enters the axial ventilation channel 102, it flows in both radial and axial directions to enter the radial ventilation channel 103 and the end ventilation channel 201, thereby realizing two cycles. The airflow in the end ventilation channel 201 ensures the unidirectional flow of the airflow in the confluence channel 104, and prevents the air flowing from the radial ventilation channel 103 into the confluence channel 104 from flowing in both directions of the stator left end winding 910 and the stator right end winding 930, thereby ensuring the smooth and efficient operation of the two cycles, especially improving the cooling effect of the first circulation path. The high-speed operation of the fan 200 provides sufficient wind pressure and air volume to support the operation of the two cycles, providing a guarantee for the cooling of the low-speed motor.

The motor air cooling system provided in this embodiment realizes that the motor shaft 100 of the low-speed motor drives the fan 200 to run at high speed through the transmission wheel group 300, thereby ensuring sufficient air volume and air pressure for cooling circulation. The first circulation path and the second circulation path allow the cold air to fully contact the heat-generating components for convection heat exchange to take away the heat. At the same time, the second circulation path ensures that the air in the first circulation path flows unidirectionally, stably and smoothly, ensuring the air circulation efficiency and cooling effect. The motor air cooling system provided in this embodiment has the advantages of high cooling efficiency, small size, high integration, simple structure, low manufacturing and use costs, and reliable operation, which provides a guarantee for the cooling of high-power low-speed motors and ensures the long-term safe and reliable operation of the motors.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. The motor air cooling system is characterized by comprising a motor rotating shaft (100), a fan (200) and a transmission wheel set (300);

the transmission wheel set (300) comprises an inner transmission wheel (310) and an outer transmission wheel (320), the inner transmission wheel (310) and the outer transmission wheel (320) are coaxially arranged, the inner transmission wheel (310) is sleeved on the motor rotating shaft (100) and connected with the motor rotating shaft (100), and the outer transmission wheel (320) is connected with the fan (200);

the inner driving wheel (310) is driven by the motor rotating shaft (100) to rotate so as to drive the outer driving wheel (320) to rotate, and then the outer driving wheel (320) drives the fan (200) to rotate so that the rotating speed of the fan (200) is higher than that of the motor rotating shaft (100).

2. The motor air cooling system according to claim 1, wherein the inner driving wheel (310) comprises a first magnet (311) and a first ring body (312), and the first magnet (311) is mounted on the first ring body (312); a plurality of first magnets (311) are uniformly distributed around the axis of the first ring body (312);

the outer transmission wheel (320) comprises a second magnet (321) and a second ring body (322), wherein the second magnet (321) is installed on the second ring body (322); the second magnets (321) are uniformly distributed around the axis of the second ring body (322).

3. The motor air cooling system according to claim 2, wherein the number of the first magnets (311) is larger than the number of the second magnets (321), and a rotation speed ratio of the inner transmission wheel (310) to the outer transmission wheel (320) is equal to a ratio of the number of the second magnets (321) to the number of the first magnets (311).

4. The motor air cooling system according to claim 2, wherein the magnetic poles of the first magnet (311) are distributed along the radial direction of the first ring body (312), and the magnetic poles of the second magnet (321) are distributed along the radial direction of the second ring body (322); the magnetic pole directions of the adjacent first magnets (311) are opposite, and the magnetic pole directions of the adjacent second magnets (321) are opposite.

5. The motor air cooling system according to claim 2, wherein the transmission wheel set (300) further comprises a magnetic modulation ring (330), and the magnetic modulation ring (330) is sleeved on the inner transmission wheel (310) and is arranged between the inner transmission wheel (310) and the outer transmission wheel (320); the magnetic tuning ring (330) comprises a ferromagnetic material and a non-ferromagnetic material which are arranged at intervals.

6. The motor air cooling system according to claim 1, further comprising a casing (400), and a rotor core (500) and a stator core (600) disposed in the casing (400), wherein the rotor core (500) is inserted into the stator core (600);

the rotor core (500), the stator core (600), the fan (200), and the casing (400) form a first circulation path; the first circulation passage comprises an air inlet passage (101), the fan (200), an axial ventilation passage (102), a radial ventilation passage (103), a converging passage (104) and a return air passage (105) which are communicated in sequence;

the air inlet channel (101) is arranged at one air inlet end of the fan (200) and is communicated with an air inlet of the shell (400); the rotor core (500) is provided with the axial ventilation channel (102) extending along the axial direction of the rotor core; the radial ventilation passage (103) extends in a radial direction of the rotor core (500) and the stator core (600) and passes through the rotor core (500) and the stator core (600); a gap extending in an axial direction of the stator core (600) between the housing (400) and the stator core (600) forms the bus duct (104); the return air channel (105) communicates with an air outlet on the housing (400) to expel air out of the housing (400).

7. The electric motor air cooling system according to claim 6, characterized in that the radial ventilation channels (103) comprise a rotor radial channel and a stator radial channel;

the rotor core (500) is divided into a plurality of sections along the axis direction of the rotor core, and gaps among the sections form the radial channels of the rotor;

the stator core (600) is divided into a plurality of sections along the axial direction thereof, and gaps between the sections form the stator radial passages.

8. The motor air cooling system according to claim 7, wherein the rotor core (500), the stator core (600), the blower (200), and the casing (400) form a second circulation path; the second circulation passage comprises an air inlet passage (101), a fan (200), an axial ventilation passage (102), an end face ventilation passage (201), a confluence passage (104) and a return air passage (105) which are sequentially communicated;

the end face ventilation channel (201) is formed by the stator core (600) and one end, far away from the air inlet channel (101), of the rotor core (500) and the machine shell (400).

9. The motor air cooling system of claim 8, further comprising a wind deflector (700), the wind deflector (700) being coupled to the housing (400) for separating the return air duct (105) and the rotor radial duct.

10. The electric motor air cooling system of claim 9, further comprising a heat exchanger (800); the heat exchanger (800) is communicated with an air outlet and an air inlet of the shell (400);

air flows along the first circulation path and the second circulation path under the drive of the fan (200); air in the heat exchanger (800) enters the air inlet channel (101) from an air inlet of the shell (400) and returns to the heat exchanger (800) from an air outlet of the shell (400) through the return air channel (105).