A structure and method for motor cooling

Abstract

This invention discloses a structure and method for cooling an electric motor, comprising a motor, a centrifugal rotating part, and an air duct. The motor includes a motor housing, a stator, coil windings, a shaft, an air inlet, and an air outlet, with the air inlet and outlet located on the motor housing. The shaft is located inside the stator and coil windings, with a gap between them. The centrifugal rotating part is located on one side of the motor. The air duct is located between the motor housing and the centrifugal rotating part. Multiple cooling air paths are provided inside the motor, with at least one path passing through the gap between the shaft, stator, and coil windings. This invention also includes a cooling method for the motor cooling structure. This invention solves the motor's heat dissipation requirements without requiring external heat dissipation components, resulting in a more compact overall size, reduced operating power, and lower overall energy consumption.

Description

Technical Field

[0001] This invention relates to the field of motor cooling technology, and in particular, to a structure and method for cooling motors. Background Technology

[0002] As the core component driving rotating machinery such as centrifugal compressors, blowers, and air pumps, electric motors have high power density and high loss density. In addition, they are small in size and compact in structure. During operation, the temperature of the motor increases rapidly, generating a large amount of heat. Furthermore, the higher the motor temperature, the lower its efficiency. The longer the motor operates at a high temperature, the shorter its service life will be.

[0003] Traditional electric motors are cooled by fans, typically either externally connected to the motor or internally connected to the shaft, to provide cooling air and control the internal temperature. Using an external fan increases the overall size and energy consumption of the motor. Conversely, using a coaxial internal fan results in a higher power consumption, wasting some shaft power for motor cooling, and further increases the overall size and manufacturing complexity.

[0004] Existing patent publication number CN115189506A discloses a self-circulating cooling magnetic levitation high-speed motor with an intercooler. The motor includes a motor body, an intercooler, and a tail impeller. The motor body includes a rotor assembly with a stator on its outer side. Magnetic bearing rotors are mounted at both ends of the rotor assembly, and a magnetic bearing stator and a magnetic bearing housing are located on its outer side. The magnetic bearing housing contains a protective bearing and a displacement sensor assembly. An air passage is provided at the top of the motor housing. One side of the intercooler at the bottom of the motor is connected to the air outlet of the motor housing, and the other side is connected to the inlet of the tail impeller. When the magnetic levitation high-speed motor is working, the driving tail impeller draws heat from the motor's interior through the air outlet of the housing, cools it through the intercooler, and then introduces it into the motor body through the impeller cover, without relying on ambient cooling air or an external fan for heat dissipation. The disadvantage of this patent is that the use of a coaxial impeller for driving cooling increases the overall power consumption and the size of the motor.

[0005] The existing patent publication number CN217010554U discloses a heat dissipation system for a permanent magnet motor in a blower, which uses a main impeller for intake cooling of the blower, but does not consider the impact of the inlet air flow and temperature after recirculation on the aerodynamic performance of the blower. Summary of the Invention

[0006] This invention primarily addresses the existing technology of using an external fan connected to the outside of the motor, or an internal fan connected to the shaft, to provide cooling air and control the internal temperature of the motor. With an external fan, adding an external air-cooling power source increases the overall size and energy consumption; while with a coaxial internal fan, the power consumption of the motor is even higher, wasting some shaft power used for motor cooling. Furthermore, adding an internal fan at the coaxial end increases the overall size and manufacturing difficulty. This invention provides a structure and method for motor cooling.

[0007] To address the aforementioned technical problems, the technical solution of the present invention is as follows:

[0008] A structure for cooling an electric motor includes a motor, a centrifugal rotating part, and an air duct. The motor includes a motor housing, a stator, coil windings, a shaft, an air inlet, and an air outlet, with the air inlet and outlet located on the motor housing. The shaft is located inside the stator and coil windings, with a gap between the stator and the shaft. The centrifugal rotating part includes an impeller air inlet, a volute air outlet, an impeller, a wheel cover, and a volute, with the wheel cover covering the outside of the impeller. The air duct is located between the motor housing and the centrifugal rotating part, with one end connected to the wheel cover and the other end connected to the motor housing. The wheel cover has an air duct port, which communicates with the motor air inlet through the air duct. The motor has multiple cooling air paths inside, with at least one cooling air path passing through the gap between the shaft, stator, and coil windings.

[0009] The location, size, and direction of the air intake are determined by CFD calculation based on the aerodynamic performance requirements and heat dissipation requirements of the motor, so that the pressure of the exhaust gas is greater than the internal air pressure loss of the motor, and the flow rate of the exhaust gas is greater than the heat dissipation of the motor under different operating conditions.

[0010] Furthermore, the impeller is disposed between the wheel cover and the volute, and the impeller is fixedly connected to the motor shaft and rotates coaxially with the shaft.

[0011] Furthermore, the air outlet of the volute is connected to the outlet of the impeller, which is used to discharge most of the gas after the impeller has done work to the external operating system.

[0012] Furthermore, the air intake channels are symmetrically arranged on the outside of the motor.

[0013] Furthermore, when the air intake port is located near the outlet side of the impeller, the pressure of the extracted gas is greater than the pressure near the air inlet of the impeller; when the opening direction of the air intake port is consistent with the flow direction (axial or radial) of the gas in the impeller, the pressure loss is less than that of a reverse opening.

[0014] Furthermore, one end of the air intake channel is connected to the motor air inlet.

[0015] Furthermore, the motor is a rotary motor, including an asynchronous motor, a synchronous motor, or a permanent magnet motor.

[0016] Furthermore, the opening direction of the air inlet is axially downward, which is the same as the main flow direction of the gas inside the impeller, thereby reducing the pressure loss when the gas is drawn out.

[0017] Furthermore, the gas pressure at the motor outlet is at least one atmosphere.

[0018] A cooling method for the above-mentioned motor cooling structure includes the following steps:

[0019] S1. Start the motor, drive the impeller to rotate through the shaft, and the gas enters from the impeller inlet. After the impeller does work and pressurizes, most of the gas is discharged to the external working system through the volute outlet.

[0020] S2. Based on the aerodynamic performance requirements and heat dissipation requirements of the motor, the position, size and direction of the air vent on the wheel cover are determined by CFD calculation, so that some high-pressure gas is drawn out from the air vent and transported to the motor air inlet through the air vent channel.

[0021] S3. The high-pressure gas enters the motor to cool the stator, coil windings, bearings and other heat-generating components.

[0022] S4. The cooled gas flows out from the motor outlet and enters the environment or a recycling system.

[0023] In step S2, the pressure of the extracted gas is greater than the internal air pressure loss of the motor, and the flow rate is adaptively adjusted according to the change of the air flow rate at the impeller inlet to match the heat dissipation requirements of the motor under different operating conditions.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. In a rotating machine employing an impeller for power, this invention involves drawing out a portion of pressurized high-pressure gas from the impeller's inlet duct for cooling the motor. An opening is made in the impeller cover to draw out the high-pressure gas. The high-pressure gas pressure satisfies the internal air pressure loss of the motor, and the gas flow rate meets the heat dissipation requirements of the motor under different loads during various operating conditions of the rotating machine. The location, size, and direction of the opening determine the flow rate and pressure of the drawn-out gas. The gas pressure gradually increases from the inlet along the arrow towards the outlet; therefore, the location and direction of the opening in the impeller cover determine the pressure of the drawn-out gas, and the size of the opening determines the flow rate. The impeller rotates coaxially with the shaft, reducing the equipment's operating power consumption and achieving energy savings. This application can simultaneously meet the aerodynamic performance requirements of the rotating machine and the motor's heat dissipation requirements under different operating conditions, reducing overall machine losses and the waste of gas flow and pressure.

[0026] 2. The flow rate, pressure, and temperature of the gas flowing out of the air outlet can all be calculated using CFD to meet the pneumatic requirements of blowers, compressors, or air pump motors of different models, power levels, and operating conditions, while also meeting the heat dissipation requirements of the motors.

[0027] 3. By using a method of opening holes in the centrifugal impeller cover at the air inlet of the rotating machinery, some of the gas that has entered the impeller is drawn out to cool the motor and control the internal temperature of the machine. This eliminates the need to add external heat dissipation components, making the whole machine more compact, reducing the operating power of the product unit, and reducing the overall energy consumption of the product. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 This is a schematic diagram illustrating the use of CFD to calculate the corresponding position in this invention;

[0030] Figure 3 This is a pressure cloud diagram representing the CFD calculation results of this invention;

[0031] Figure 4 This is a temperature contour plot of the CFD calculation results of the present invention.

[0032] In the above diagram, 1. Impeller inlet; 2. Impeller cover; 3. Air intake channel; 4. Impeller; 5. Air intake port; 6. Volute; 7. Volute outlet; 8. Motor inlet; 9. Shaft; 10. Stator; 11. Motor housing; 12. Motor outlet; 13. Coil winding. Detailed Implementation

[0033] To clearly illustrate the technical features of the present invention, the present invention will be described in detail below through specific embodiments and in conjunction with the accompanying drawings.

[0034] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0035] Furthermore, in the description of this invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0036] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0037] In this invention, unless otherwise expressly specified and limited, the first feature "on" or "below" the second feature may be in direct contact with the first and second features, or indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0038] Example 1

[0039] like Figure 1As shown, a structure for cooling an electric motor includes a motor, a centrifugal rotating part, and an air duct 3. The motor includes a motor housing 11, a stator 10, a coil winding 13, a rotating shaft 9, a motor air inlet 8, and a motor air outlet 12. The motor air inlet 8 and the motor air outlet 12 are located on the motor housing 11. The rotating shaft 9 is located inside the stator 10 and the coil winding 13, and there is a gap between the stator 10 and the rotating shaft 9. The centrifugal rotating part includes an impeller air inlet 1, a volute air outlet 7, an impeller 4, and a wheel. The impeller 4 is covered by a cover 2 and a volute 6. The cover 2 covers the outside of the impeller 4. The air intake channel 3 is located between the motor housing 11 and the centrifugal rotating part. One end of the air intake channel 3 is connected to the cover 2 and the other end is connected to the motor housing 11. The cover 2 is provided with an air intake port 5, which is connected to the motor air inlet 8 through the air intake channel 3. The motor is provided with multiple cooling air passages, at least one of which passes through the gap between the rotating shaft 9, the stator 10 and the coil winding 13.

[0040] The position, size, and direction of the air inlet 5 are determined by CFD calculation based on the aerodynamic performance requirements and heat dissipation requirements of the motor, so that the pressure of the outgoing gas is greater than the internal air pressure loss of the motor, and the flow rate of the outgoing gas is greater than the heat dissipation of the motor under different operating conditions.

[0041] In this embodiment, the impeller 4 is disposed between the wheel cover 2 and the volute 6. The impeller 4 is fixedly connected by the motor shaft 9, and the impeller 4 rotates coaxially with the motor shaft 9 to perform work and pressurize the gas, thereby improving working efficiency.

[0042] The air intake channel 3 and the air intake port 5 are connected. The air intake port 5 is located on the wheel cover, and the air intake channel 3 is connected to the wheel cover 2 and the motor housing 11 respectively. The gas drawn from the air intake port 5 is low-temperature gas, which meets the heat dissipation and cooling requirements of the motor. The gas drawn from the air intake port 5 is high-pressure gas, and the gas pressure meets the requirements of motor airflow loss, so that the gas pressure at the motor outlet 12 only needs to be one atmosphere.

[0043] In this embodiment, when the motor is running, the rotation of the shaft 9 drives the impeller 4 to rotate. Gas enters from the impeller inlet 1, and the impeller 4 performs work and pressurizes this gas by rotating it. Most of the gas is pressurized by the rotation of the impeller 4 and finally enters the volute outlet 7. The high-temperature and high-pressure gas flows out from the volute outlet 7 and is used for manufacturing. Some gas flows out from the air duct 5 on the wheel cover 2, passes through the air duct 3, and enters the motor inlet 8 to cool the internal structure of the motor, such as the rotor and coils. After cooling, the gas flows out from the motor outlet 12.

[0044] In this embodiment, the drive motor is included, but is not limited to, other types of rotating motors. During operation, the impeller 4 performs work. When the air flow rate at the impeller inlet 1 is large, the impeller 4 performs a large amount of work, the motor power increases, losses increase, and more heat needs to be dissipated. Due to the increased flow rate at the impeller inlet 1, the air flow rate drawn from the exhaust port 5 also increases. When the air flow rate at the impeller inlet 1 is small, the impeller 4 performs a small amount of work, the motor power decreases accordingly, and losses decrease. Due to the decreased flow rate at the impeller inlet 1, the air flow rate drawn from the exhaust port 5 also decreases. Therefore, under different operating conditions, this structure can simultaneously meet the aerodynamic performance requirements of rotating machinery and the motor heat dissipation requirements, while reducing overall machine losses and the waste of gas flow and pressure.

[0045] In this embodiment, the cooling method of the motor cooling structure of the present invention includes the following steps:

[0046] S1. Start the motor and drive the impeller 4 to rotate through the shaft 9. The gas enters from the impeller inlet 1 and is pressurized by the impeller 4. Most of the gas is discharged to the external working system through the volute outlet 7.

[0047] S2. Based on the aerodynamic performance requirements and heat dissipation requirements of the motor, the position, size and direction of the air inlet 5 on the wheel cover 2 are determined by CFD calculation, so that some high-pressure gas is drawn out from the air inlet 5 and transported to the motor air inlet 8 through the air inlet channel 3.

[0048] S3. The high-pressure gas enters the motor to cool the stator 10, coil winding 13 and bearings and other heat-generating components.

[0049] S4. The cooled gas flows out from the motor outlet 12 and enters the environment or the recycling system.

[0050] In step S2, the pressure of the extracted gas is greater than the internal air pressure loss of the motor, and the flow rate is adaptively adjusted according to the air flow rate at the impeller inlet 1 to match the heat dissipation requirements of the motor under different operating conditions.

[0051] Example 2

[0052] In this embodiment, the size, installation position, and installation direction of the air vent 5 are determined according to the flow rate and pressure required for motor cooling. The outflow rate and pressure are calculated by CFD to simultaneously meet the outlet pressure and flow rate requirements of rotating machinery and the motor heat dissipation requirements.

[0053] Since the air intake 5 is located on the wheel cover 2 above the impeller 4, the pressure varies depending on the air intake position. Specifically, the closer the air intake 5 is to the outlet of the impeller 4, the greater the pressure of the gas drawn out; the closer it is to the air intake 1, the lower the pressure. Because the impeller 4 rotates and performs work during operation, the pressure loss of the gas entering through different air intake 5 directions varies. To ensure both excellent aerodynamic performance and the motor's heat dissipation requirements, the pressure loss of the gas drawn out through the air intake 5 direction is minimized. Specifically, during motor operation, gas enters through the impeller inlet 1, is pressurized by the rotation of the impeller 4, and finally flows from the impeller inlet 1 to the volute outlet 7. The gas flow direction is primarily axial downwards initially, then radially due to the centrifugal force of the impeller 4, finally flowing to the volute outlet 7. The direction of the opening on the wheel cover 2 determines the outflow rate and pressure. When the opening is axially downward, the flow is basically in the same direction, the pressure loss is small, and the outflow rate and pressure are greater. When the opening is radially or axially upward, the pressure loss will be greater when the gas flows out from the air inlet 5, which will affect the flow rate and pressure of the gas entering the motor from the motor air inlet 8.

[0054] The amount of heat generated by the motor itself can be determined from its losses. This can be expressed as Q = c * M * ΔT, where Q is the heat generated by the motor, c is the specific heat capacity of air, M is the air mass flow rate, and ΔT is the temperature difference between the air entering and leaving the motor. From this formula, we can see that the heat generated by the motor determines the required flow rate and temperature at the motor inlet 8. The gas pressure gradually increases from the impeller inlet 1 along the arrow to the outlet 7. Therefore, the closer the opening on the impeller cover 2 is to the rear of the arrow, the greater the pressure; the larger the opening, the greater the flow rate. Figure 2 and Figure 3 As shown, the arrows indicate the direction of gas flow.

[0055] In this embodiment, CFD calculations can be performed by establishing an aerodynamic model to calculate the flow rate, pressure, and temperature exiting from the air inlet 5. Taking a certain type of blower as an example: the impeller 4 has long and short blades, the pressure at the impeller inlet 1 is set to 100 kPa, and the total inlet flow rate is 60.5 m³ / s. 3 / min, a 6.5mm diameter annular opening is made on wheel cover 2 at a 65° angle (perpendicular to the axial direction). Figure 3 The air intake pores are located at the tip of the short blade. Calculations show that... Figure 3 The pressure at the location of air inlet 5 in the cloud diagram is approximately in the range of 103-120 kPa; Figure 4Temperature cloud map: The temperature at bleed inlet 5 is approximately 35-60℃. Taking the data from the outlet section of bleed inlet 5, the final outlet pressure is 115 kPa, the outlet temperature is 40℃, and the outlet flow rate is 82 m³ / s. 3 / h, meeting the general air-cooling requirements of motors.

[0056] Example 3

[0057] In this embodiment, the bearing connected to the motor shaft 9 is not limited to rolling bearings, magnetic bearings, air bearings, or sliding bearings, but may also be other bearings.

[0058] The motor can be an asynchronous motor, a synchronous motor or a permanent magnet motor. The cooling structure of this invention can be applied to air compressors, blowers, pumps or other mechanisms driven by the rotation of impeller 4.

[0059] Obviously, the embodiments described above are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A structure for cooling an electric motor, characterized in that, The system includes a motor, a centrifugal rotating part, and an air duct. The motor includes a motor housing, a stator, coil windings, a shaft, an air inlet, and an air outlet, both located on the motor housing. The shaft is located inside the stator and coil windings, with a gap between them. The centrifugal rotating part includes an impeller air inlet, a volute air outlet, an impeller, a wheel cover, and a volute, with the wheel cover covering the outside of the impeller. The air duct is located between the motor housing and the centrifugal rotating part, with one end connected to the wheel cover and the other end connected to the motor housing. The wheel cover has an air duct opening. The air vent is connected to the motor air inlet through the air vent channel; the motor has multiple cooling air paths inside, at least one of which passes through the gap between the shaft, stator, and coil windings; the impeller is located between the wheel cover and the volute, and is fixedly connected to the motor shaft and rotates coaxially with the shaft; the position, size, and direction of the air vent are determined by CFD calculation based on the motor's aerodynamic performance and heat dissipation requirements, ensuring that the pressure of the vented gas is greater than the internal air pressure loss of the motor, and the flow rate of the vented gas is configured to carry away all the heat generated by the motor under different operating conditions.

2. The structure for cooling an electric motor according to claim 1, characterized in that, The air outlet of the volute is connected to the outlet of the impeller, and is used to discharge most of the gas after the impeller has done work to the external operating system.

3. The structure for motor cooling according to claim 1, characterized in that, The air intake channels are symmetrically arranged on the outside of the motor.

4. The structure for cooling an electric motor according to claim 1, characterized in that, When the air intake port is located near the outlet side of the impeller, the pressure of the extracted gas is greater than the pressure near the air inlet of the impeller; when the opening direction of the air intake port is consistent with the flow direction of the gas in the impeller, the pressure loss is less than that of the reverse opening.

5. A structure for cooling an electric motor according to claim 1, characterized in that, One end of the air intake channel is connected to the motor air inlet.

6. The structure for cooling an electric motor according to claim 1, characterized in that, The motor is a rotary motor, including asynchronous motors and synchronous motors.

7. A structure for cooling an electric motor according to claim 1, characterized in that, The air intake is oriented axially downwards, in the same direction as the main flow direction of the gas inside the impeller, which reduces the pressure loss when the gas is drawn out.

8. A structure for cooling an electric motor according to claim 1, characterized in that, The gas pressure at the motor outlet is at least one atmosphere.

9. A cooling method based on the motor cooling structure according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Start the motor, drive the impeller to rotate through the shaft, and the gas enters from the impeller inlet. After the impeller does work and pressurizes, most of the gas is discharged to the external working system through the volute outlet. S2. Based on the aerodynamic performance requirements and heat dissipation requirements of the motor, the position, size and direction of the air vent on the wheel cover are determined by CFD calculation, so that some high-pressure gas is drawn out from the air vent and transported to the motor air inlet through the air vent channel. S3. The high-pressure gas enters the motor to cool the stator, coil windings, and bearings; S4. The cooled gas flows out from the motor outlet and enters the environment or a recycling system. In step S2, the pressure of the extracted gas is greater than the internal air pressure loss of the motor, and the flow rate is adaptively adjusted according to the change of the air flow rate at the impeller inlet to match the heat dissipation requirements of the motor under different operating conditions.

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