Phase change cooling structure of axial disc type permanent magnet motor

Abstract

A phase change cooling structure of an axial disc type permanent magnet motor is characterized in that exhaust holes are arranged on a shell of the axial disc type permanent magnet motor, an air flow duct and a phase change body are arranged in a rotating shaft, one end of the air flow duct in the rotating shaft is communicated with an air gap, and the phase change body in the rotating shaft is located at a position outside a position where the air flow duct is communicated with the air gap. The rotating kinetic energy of a rotating shaft in the axial disc type permanent magnet motor is utilized, airflow is generated when the rotating shaft rotates, the airflow is introduced into the rotating shaft and cooled in the rotating shaft through a phase change body, and then the low-temperature airflow enters an air gap between a stator and a rotor, flows through the surface of the stator and the surface of the rotor along the air gap and then returns to the back face of the rotor to be discharged. According to the structure, on the basis of the internal structure of the motor, the temperature of air entering the motor is reduced through the characteristics of the phase change material in the phase change body, the cooling efficiency is improved, and the production cost and the maintenance cost are reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to a structure for cooling axial disc type permanent magnet motor belongs to axial permanent magnet motor cooling technical field. BACKGROUND

[0002] The basic structure of the axial disc type permanent magnet motor is shown in Figure 3 , which comprises a housing 13, a stator 5, a rotor 4 and a rotating shaft 10. The rotating shaft 10 is installed in the housing through bearings, and the rotating shaft 10 is connected with the rotor 4 through the flange 16 thereon. One end of the rotating shaft 10 extends out of the housing 13. The rotor is composed of two rotor yokes 9 (two metal plates) and the patch magnetic poles 14 (in the form of a ring structure) arranged on the inner side of the rotor yokes 9. When the two rotor yokes 9 move relative to each other in an alternating magnetic field, electromagnetic force is generated between them to attract each other. The stator 5 and the rotor 4 are arranged in the housing 13, and the stator 5 is located inside the rotor 4 (between the two rotor yokes 9). There is an air gap between the stator 5 and the rotor yokes 9 on both sides thereof. The magnetic field generated between the stator 5 and the rotor 4 converts electrical energy into mechanical energy. When the rotor 4 rotates, copper loss, iron loss and eddy current loss are generated, and the losses are ultimately converted into heat. Cooling the heat generated by the motor is mainly to reduce the temperature influence on the stator and the rotor permanent magnet. The higher the power of the motor, the greater the temperature rise, and cooling methods need to be used to prevent the motor from being damaged. The existing cooling methods include natural cooling, air cooling, water cooling and oil-gas mixed cooling. Different cooling methods have different complexities, maintenance costs and fault points.

[0003] Due to the use of a closed process by the axial permanent magnet motor, the generated heat is not easy to discharge, and poor heat dissipation is a problem that needs to be solved urgently for the motor.

[0004] In the prior art, the axial permanent magnet motor adopts an external auxiliary cooling air cooling method or an external circulation cooling water channel method. The external auxiliary air cooling method is shown in Figure 1 , which uses an external fan 1 to forcibly blow cold air into the motor interior for heat dissipation. This method installs the fan on the rotating shaft of the motor, which not only increases the axial length of the motor, but also increases the additional fan loss and reduces the motor efficiency. The external circulation cooling water channel method is shown in Figure 2 , which needs to cast a cooling water channel 2 in the housing. The molding sand core method is used to fix the sand core in the casting mold, and after solidification and cooling, the sand core is taken out to form the cooling water channel in the housing. New molding sand cores need to be made for each casting, which is a complex process with low efficiency and high cost. An additional cooling circulation system 3 is also needed to provide circulating liquid for the cooling water channel 2, which not only increases the cost of the motor, but also increases the cost of regular maintenance and replacement of the cooling liquid. The existing disc type permanent magnet motor cooling technology does not have industry-wide specifications, and all refer to the temperature rise index of the radial permanent magnet motor. SUMMARY

[0005] The axial disc type permanent magnet motor phase change cooling structure has high cooling efficiency, and can reduce production cost and maintenance cost.

[0006] The axial disc type permanent magnet motor phase change cooling structure has the following technical scheme:

[0007] The cooling structure is provided with an exhaust hole on the shell of the axial disc type permanent magnet motor, and an airflow duct and a phase change body are arranged in the rotating shaft; one end of the airflow duct in the rotating shaft is communicated with the air gap; and the phase change body is arranged at a position outside the airflow duct and the air gap in the rotating shaft.

[0008] The airflow duct is in the shape of a round hole, a square hole, a triangular hole or other special-shaped hole.

[0009] The airflow duct is communicated with the air gap by being provided with a ventilation hole in the flange connected between the rotating shaft and the rotor.

[0010] The inner wall of the airflow duct is provided with air grooves, and the air grooves are axial grooves.

[0011] The phase change body is a sealed cavity filled with a phase change material; the phase change body can be arranged at the bottom end of the airflow duct in the rotating shaft, or can be arranged on the inner wall of the airflow duct, but cannot block the airflow duct and the ventilation hole communicated with the airflow duct and the air gap.

[0012] The rotating kinetic energy of the rotating shaft in the axial disc type permanent magnet motor is utilized to generate airflow when the rotating shaft rotates; the airflow is introduced into the rotating shaft, and the airflow is cooled by the phase change body in the rotating shaft; then the low-temperature airflow enters the air gap between the stator and the rotor, flows along the surface of the stator and the surface of the rotor, and is discharged from the back surface (the surface opposite to the inner wall of the shell) of the rotor, so that the heat in the motor is released, and the heat in the motor is cooled.

[0013] The air temperature entering the motor is reduced by the characteristics of the phase change material in the phase change body on the basis of the internal structure of the disc type permanent magnet motor; the comprehensive heat exchange coefficient is increased by utilizing the airflow channel; the internal heat which does not flow originally is changed into circulating positive pressure airflow; the comprehensive heat exchange coefficient is increased from 10 to about 150; the heat dissipation Q is greatly improved; the working temperature of the motor is reduced; the cooling efficiency is improved; the internal heat of the motor is rapidly released; the production cost and the maintenance cost are reduced; the normal operation of the motor is ensured; and the problem that the structure of the axial disc type permanent magnet motor is not easy to dissipate heat is solved. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1It is the principle diagram of external air cooling structure of prior axial disc type permanent magnet motor.

[0015] Figure 2 It is the principle diagram of external circulation cooling structure of prior axial disc type permanent magnet motor.

[0016] Figure 3 It is the schematic diagram of phase change cooling structure of axial disc type permanent magnet motor in the utility model.

[0017] Figure 4 It is the sectional schematic diagram of rotor in cooling structure.

[0018] Figure 5 It is the schematic diagram of airflow channel in rotating shaft.

[0019] Figure 6 It is the schematic diagram of air groove distributed on inner wall of airflow channel.

[0020] In the drawing: 1. external fan, 2. external cooling water channel, 3. cooling circulation system, H. external dimension of motor;

[0021] 4. rotor, 5. stator, 6. exhaust hole, 7. air gap, 8. phase change body, 9. rotor yoke, 10. rotating shaft, 11. airflow channel, 12. air hole, 13. shell, 14. magnetic pole, 15. air groove, 16. flange, 17. end cover. DETAILED DESCRIPTION

[0022] The phase change cooling structure of axial disc type permanent magnet motor in the utility model, as shown in Figure 3 , Figure 4 and Figure 5 , specifically sets up exhaust hole 6 on shell, sets up airflow channel 11 in rotating shaft 10, airflow channel 11 is blind hole, outer end is communicated with atmosphere, the shape of airflow channel 11 can be round hole, square hole, triangular hole or other special-shaped hole.Set up axial air groove 15 (see Figure 5 and Figure 6 ) on the inner wall of airflow channel 11.Set up air hole 12 (see Figure 3 and Figure 5 ) communicated with airflow channel 11 on the flange 16 of rotating shaft 10, make airflow channel 11 communicated with air gap 7 through air hole 12.Form airflow structure through airflow channel 11 in rotating shaft 10, air channel 12 in flange 16 and exhaust hole 6 on shell 13, Figure 3 in which arrow represents airflow direction.Set up phase change body 8 in rotating shaft 10, see Figure 5, the phase change body 8 is a closed cavity filled with phase change material, and the phase change body 8 is located at the bottom end of the airflow duct 11 in the rotating shaft 10 and is fixed by the end cover 17. The phase change body 8 can also be arranged on the inner wall of the airflow duct 11, but cannot block the airflow duct 11 and the air vent 12 communicating with the airflow duct 11 and the air gap 7. The phase change material is a kind of intelligent material that can absorb or release heat when the substance changes phase without changing the temperature of the substance itself. Phase change materials are diverse, and there are various classification methods. According to the phase change mode, they can be divided into gas-liquid, solid-gas, solid-liquid and solid-solid. Among them, solid-liquid can be divided into organic PCMs, inorganic PCMs and eutectic compounds according to the structure.

[0023] The above cooling structure constructs the airflow duct 11 by partially hollowing the inside of the rotating shaft 10. According to aerodynamics, the rotational kinetic energy of the rotating shaft 10 in the motor is used to make the external airflow enter the inside of the motor. When the rotating shaft 10 rotates, air enters through the airflow passage 11 built in the rotating shaft 10, negative pressure is generated at the shaft end, air outside the motor is sucked into the airflow passage 11 in the rotating shaft 10, and the air flows in the direction guided by the airflow duct 11, exchanges heat with the built-in phase change body 8 when reaching the inner end of the airflow duct 11 (the phase change body 8 absorbs the heat in the air), forms a low-temperature cold airflow, and the cold airflow enters the air gap 7 between the stator 5 and the rotor yoke 9 on both sides of the stator 5 through the radial air vents 12 distributed in the flange 16 on the rotating shaft 10 (the flange 16 rotates with the rotating shaft 10), and forms two airflows flowing along the surface of the stator 5 and the surface of the rotor 4 respectively. The airflows reach the maximum outer diameter of the rotor 4 (the outermost side of the air gap 7), turn back to the back of the rotor 4 (the rotor yoke 9), pass through the gap between the rotor 4 and the inner wall of the outer shell 13, continue to flow to the air exhaust hole 6 on the outer shell, and finally are exhausted through the air exhaust hole 6, releasing the heat in the motor to the outside of the motor, achieving the function of heat exchange between the inside of the motor and the outside cold air, and ensuring the normal operation of the motor.

[0024] The heat dissipation Q of the rotating shaft 10 is calculated according to the following formula:

[0025] Q = a (tw - to) F, where Q is the heat dissipation, w.

[0026] tw is the surface temperature of the heat dissipation surface (the surface of the stator and the surface of the rotor yoke), ℃.

[0027] to is the external environment temperature (air temperature), ℃.

[0028] F is the area of the heat dissipation surface (the surface of the stator and the surface of the rotor yoke), m 2 .

[0029] a is the comprehensive heat exchange coefficient, w / (℃×m 2 ).

[0030] The ambient temperature to (external air temperature) entering the inside of the motor (air flow passage 11 in the rotating shaft 10) is reduced by the characteristics of the phase change body 8, the comprehensive heat exchange coefficient a is increased by the rotating shaft 10, the air flow passage 11 and the air slot, the internal heat which originally does not flow is changed into circulating positive pressure air flow, the comprehensive heat exchange coefficient a is increased from the original 10 to about 150, the heat dissipation Q is greatly increased, and the working temperature of the motor is reduced.

[0031] Through testing, the surface temperature of the motor with this structure is about 15 degrees Celsius lower than that of the motor without this structure.

Claims

1. A phase change cooling structure for an axial disc permanent magnet electric machine, characterized by, The exhaust hole is arranged on the shell of the axial disc type permanent magnet motor, the airflow channel and the phase change body are arranged in the rotating shaft, one end of the airflow channel in the rotating shaft is communicated with the air gap, and the phase change body is arranged in the rotating shaft at a position outside the airflow channel communicated with the air gap.

2. The axial disc-type permanent magnet motor phase change cooling structure according to claim 1, characterized by, The shape of the airflow channel includes a round hole, a square hole and a triangular hole.

3. The axial disc-type permanent magnet motor phase change cooling structure according to claim 1, characterized in that, The airflow channel is communicated with the air gap inside the motor by arranging the air hole in the flange connected with the rotor of the motor.

4. The axial disc-type permanent magnet motor phase change cooling structure according to claim 1, characterized by, The inner wall of the airflow channel is distributed with air grooves.

5. The axial disc-type permanent magnet motor phase change cooling structure according to claim 1, characterized by, The phase change body is a sealed cavity filled with phase change material.

6. The phase change cooling structure of an axial disc-type permanent magnet motor according to claim 1 or 5, characterized in that, The phase change body is arranged at the bottom end of the airflow channel in the rotating shaft.

7. The phase change cooling structure of an axial disc-type permanent magnet motor according to claim 1 or 5, characterized in that, The phase change body is arranged on the inner wall of the airflow channel.

Images