Water-air combined cooling system for efficient heat exchange of permanent magnet motor
By combining water cooling and pneumatic heat exchange systems in a permanent magnet motor, and utilizing the pneumatic heat exchange tubes driven by the permanent magnet rotor and the annular hollow liquid cooling cavity, the problem of heat dissipation difficulties in the sealed stator and rotor cavity is solved, achieving a highly efficient heat exchange effect and improving motor performance and reliability.
Patent Information
- Application Number
- CN202511443102.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-10
- Publication Date
- 2026-02-27
AI Technical Summary
In high-torque permanent magnet motors, heat is difficult to dissipate in the sealed stator and rotor cavities, resulting in excessive temperature rise. Existing cooling methods are inefficient and increase additional power consumption and cost.
Combining water cooling and pneumatic heat exchange systems, using pneumatic heat exchange tubes driven by permanent magnet rotors and annular hollow liquid cooling chambers, convective heat exchange is achieved by periodically deforming the blower diaphragm through magnetic attraction, thus avoiding the need for additional power devices.
It improves the heat exchange efficiency in the sealed stator and rotor cavity, reduces the motor temperature rise, improves motor performance and lifespan, simplifies the structure, and reduces costs.
Smart Images
Figure CN121584932A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electric motors. Background Technology
[0002] In the application of high-torque permanent magnet motors, effective cooling design is crucial to ensuring motor performance, efficiency, and service life. Common cooling methods mainly suffer from the following problems:
[0003] In a closed stator and rotor cavity, the internal air cannot convect effectively with the outside, making it difficult to dissipate heat and easily leading to heat accumulation, resulting in excessive motor temperature rise; in addition, the fan has limited air pressure and air volume at low speeds, resulting in unsatisfactory cooling effect.
[0004] Limitations of water cooling alone: Although water cooling can effectively remove heat from the outside of the stator, it is difficult to effectively manage the heat generated inside the stator coils and rotor and transferred to the air inside the stator and rotor cavities; the hot air inside the sealed cavity becomes a heat insulation layer, which hinders further heat transfer from the inside of the stator to the housing.
[0005] To address internal heat dissipation issues, some solutions employ independent forced air cooling or oil cooling systems. However, this increases power consumption, introduces complex sealing structures, and raises manufacturing costs, thereby reducing the overall reliability and cost-effectiveness of the system. Summary of the Invention
[0006] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides a water-air combined cooling system for high-efficiency heat exchange of permanent magnet motors, which can improve the heat exchange efficiency in the sealed stator and rotor cavities.
[0007] Technical Solution: To achieve the above objectives, the present invention provides a water-air combined cooling system for high-efficiency heat exchange of a permanent magnet motor, comprising a water-air combined cooling housing, with a front end cover and a rear end cover encapsulated and connected at both ends of the housing; a stator and rotor cavity is enclosed within the water-air combined cooling housing; a stator coil and a permanent magnet rotor are coaxially arranged within the stator and rotor cavity; the stator coil is coaxially heat-transferring and in contact with the inner surface of the water-air combined cooling housing; the permanent magnet rotor rotates coaxially within the area enclosed by the stator coil, and is coaxially mounted on a rotor shaft, which is rotated and fitted with the front end cover and the rear end cover via bearings;
[0008] The section of the water-air combined cooling housing that is heat-contacted by the stator coil has an annular hollow liquid-cooled cavity inside; several pneumatic heat exchange tubes are arranged in a circumferential array inside the annular hollow liquid-cooled cavity.
[0009] Furthermore, the upper end of the annular hollow liquid cooling cavity is divided by a partition wall, which cuts off the upper end of the annular hollow liquid cooling cavity. It also includes a coolant inlet pipe and a coolant outlet pipe, which are respectively connected to the left and right sides of the annular hollow liquid cooling cavity of the partition wall. The coolant inlet pipe flows into the clockwise end of the annular hollow liquid cooling cavity, flows in the counterclockwise direction through the entire annular hollow liquid cooling cavity, and then flows out from the counterclockwise end of the annular hollow liquid cooling cavity through the coolant outlet pipe.
[0010] Furthermore, the outer wall of each pneumatic heat exchange tube maintains a gap with the inner and outer walls of the annular hollow liquid-cooled cavity, and the outer wall of each pneumatic heat exchange tube is immersed in the coolant inside the annular hollow liquid-cooled cavity.
[0011] Furthermore, the extension direction of each pneumatic heat exchange tube is parallel to the axis of the water-air combined cooling housing.
[0012] Furthermore, a ring groove is coaxially arranged on the inner side of the rear of the water-air combined cooling housing, and a ring-shaped elastic diaphragm is also coaxially covering the ring groove. The outline edge of the ring-shaped elastic diaphragm is sealed to the edge outline of the ring groove.
[0013] Several isolation seats are integrally arranged in a circular array inside the annular groove. The annular elastic diaphragm is fixed to the end of each isolation seat by sealant, so that the several isolation seats divide the annular groove into several air chambers distributed in a circular array. The annular elastic diaphragm covering each air chamber is referred to as the air diaphragm. An iron plate is fixed on the side of each air diaphragm near the air chamber.
[0014] The front end of each pneumatic heat exchange tube is the gas suction and spray end connected to the stator and rotor chamber, and the rear end of each pneumatic heat exchange tube is the pressure transmission end connected to the blower chamber.
[0015] The iron sheet is elastically supported and connected to the inner wall of the cooling housing by a support spring; a permanent magnet is fixedly connected to the circumferential surface of the rotor tail end in the radial direction; an annular elastic diaphragm is coaxially surrounded on the outer ring of the rotor tail end. As the permanent magnet rotates with the permanent magnet rotor, the permanent magnet corresponds to several iron sheets distributed in a circular array. When the permanent magnet and the iron sheet correspond, the permanent magnet forms a magnetic attraction force on the iron sheet.
[0016] Furthermore, during motor operation, coolant continuously flows into the clockwise end of the annular hollow liquid cooling cavity through the coolant inlet pipe, and then flows counterclockwise through the entire annular hollow liquid cooling cavity before continuously flowing out from the counterclockwise end of the annular hollow liquid cooling cavity through the coolant outlet pipe, thereby continuously carrying away the heat from the combined water and air cooling of the housing and the outer ring of the stator coil.
[0017] Furthermore, during the rotation of the permanent magnet rotor, as the permanent magnet rotates along with it, the permanent magnet will successively correspond to several iron plates arranged in a circular array. When the permanent magnet corresponds to any iron plate, it will generate a magnetic attraction force on the iron plate. Under the action of the magnetic attraction force, the iron plate will push the blower diaphragm to become convex and move closer to the permanent magnet, thereby increasing the volume of the corresponding blower cavity. As the permanent magnet rotor rotates, when the iron plate is misaligned with the permanent magnet, the iron plate and the blower diaphragm will reset under the elastic tension of the support spring, thus restoring the volume of the blower cavity.
[0018] Beneficial effects: This solution integrates a pneumatic heat exchange system driven by a permanent magnet rotor and based on air pressure inside the liquid cooler housing; the system combines the annular hollow liquid cooling cavity surrounding the stator with the circumferential array of pneumatic heat exchange tubes, so that liquid cooling and internal air cooling are no longer two independent systems, but are integrated into a highly efficient integral heat exchanger through the heat exchange tube wall.
[0019] By utilizing the rotation of the motor rotor itself as a power source, and through the magnetic attraction between permanent magnets and iron plates, as well as supporting springs, the rotational motion is converted into periodic pulsations of the blower diaphragm. This design eliminates the need for an additional motor or fan, achieving passive and forced agitation and circulation of air within the sealed stator and rotor chambers.
[0020] The periodic change in the volume of the blower chamber generates directional air pressure within the pneumatic heat exchange tubes. This causes the heat exchange tubes to not simply conduct, but to actively and periodically "draw in" hot air from the stator and rotor chambers and "eject" cooled air into them. This flow effectively breaks down the static insulation layer of the internal hot air, greatly enhancing the convective heat transfer efficiency between the gas and liquid.
[0021] The annular elastic diaphragm, isolation seat, iron sheet, and support spring are integrated into a compact blower module and cleverly arranged at the end of the rotor. This structure utilizes magnetic force for non-contact drive, avoiding complex mechanical transmission and dynamic sealing problems, ensuring reliable operation, long service life, and making it particularly suitable for operation in the enclosed environment of the motor. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the overall structure of the motor in this solution. The front and rear covers of the motor are omitted in this diagram.
[0023] Figure 2 A cross-sectional view of the motor with the front and rear end covers removed;
[0024] Figure 3 This is a sectional view along the BB direction of this scheme;
[0025] Figure 4 This is the AA-direction sectional view of this scheme. Detailed Implementation
[0026] The invention will now be further described with reference to the accompanying drawings.
[0027] As shown in the attached diagram. Figures 1 to 4 This invention illustrates a high-efficiency water-air combined cooling system for permanent magnet motors. This system is designed for low-speed, high-torque permanent magnet motors. Traditional cooling methods for these motors, such as simple air cooling or water cooling, are often inefficient, especially in the enclosed stator and rotor cavities where heat accumulation easily occurs, affecting motor performance and lifespan. This solution innovatively combines water cooling with pneumatic heat exchange, effectively solving this problem. Specifically, it includes a cylindrical water-air combined cooling housing 1, with a front cover and a rear cover respectively enclosed by flanges at both ends. The stator and rotor cavities 90 are enclosed within the water-air combined cooling housing 1. A stator coil 12 and a permanent magnet rotor 4 are coaxially arranged within the stator and rotor cavities 90. The stator coil 12 is coaxially heat-transferring and in contact with the inner surface of the water-air combined cooling housing 1. The permanent magnet rotor 4 rotates coaxially within the area enclosed by the stator coil 12 and is coaxially mounted on a rotor shaft 81. The rotor shaft 81 rotates in conjunction with the front and rear covers via bearings. Figure 1 and 3 The front and rear covers are concealed. The water-air combined cooling housing 1 is made of high-strength aluminum alloy; the stator coil 12 is made of copper wire and coated with insulating varnish, directly attached to the inner ring of the housing to maximize heat conduction; the permanent magnet rotor 4 uses neodymium iron boron permanent magnet material, suitable for low-speed, high-torque applications.
[0028] An annular hollow liquid-cooled cavity 2 is provided inside the section of the water-air combined cooling housing 1 that is heat-conducting and bonded to the stator coil 12. A partition wall 22 is provided at the upper end of the annular hollow liquid-cooled cavity 2, cutting off its upper end. The partition wall 22 also includes a coolant inlet pipe 20 and a coolant outlet pipe 21, which connect to the left and right sides of the annular hollow liquid-cooled cavity 2, respectively. The coolant flows into the clockwise end of the annular hollow liquid-cooled cavity 2 through the partition wall 20, flows counterclockwise through the entire annular hollow liquid-cooled cavity 2, and then flows out through the coolant outlet pipe 21 from the counterclockwise end of the annular hollow liquid-cooled cavity 2. The coolant circulating inside is an ethylene glycol aqueous solution with a volume concentration of 40-60%, and the flow rate is controlled at 2-5 L / min to ensure efficient heat removal. The partition wall 22 is made of stainless steel and welded inside the liquid-cooled cavity to ensure sealing and durability.
[0029] A number of pneumatic heat exchange tubes 5 are arranged in a circumferential array within the annular hollow liquid-cooled cavity 2. The outer wall of each pneumatic heat exchange tube 5 maintains a gap with both the inner and outer walls of the annular hollow liquid-cooled cavity 2, and the outer wall of each pneumatic heat exchange tube 5 is immersed in the coolant within the annular hollow liquid-cooled cavity 2. The extension direction of each pneumatic heat exchange tube 5 is parallel to the axis of the water-air combined cooling housing 1. The pneumatic heat exchange tubes 5 are made of thin-walled copper tubes with an inner diameter of 5-8 mm and a wall thickness of 0.5-1 mm. There are 12-24 tubes arranged in a circumferential array, evenly distributed to maximize the heat exchange area. The gap between the outer wall of the pneumatic heat exchange tube 5 and the wall of the liquid-cooled cavity is 2-4 mm, allowing the coolant to flow freely and enhancing the convective heat transfer effect.
[0030] The water-air combined cooling housing 1 has a ring groove 6 coaxially arranged on the inner side of the rear end, and also includes a ring-shaped elastic diaphragm 7 coaxially covering the ring groove 6. The outline edge of the ring-shaped elastic diaphragm 7 is sealed to the edge outline of the ring groove 6 by means of sealant or compression. The ring-shaped elastic diaphragm 7 is made of silicone rubber with a thickness of 1-2mm, has high elasticity and heat resistance, and has an operating temperature range of -40℃ to 150℃. It achieves airtight sealing by epoxy sealant.
[0031] A plurality of isolation seats 8 are integrally arranged in a circular array within the annular groove 6. Annular elastic diaphragms 7 are fixedly attached to the ends of each isolation seat 8 using epoxy sealant, thus dividing the annular groove 6 into a plurality of circumferentially distributed air chambers 6a. The annular elastic diaphragms 7 covering each air chamber 6a are designated as air diaphragms 7a. An iron sheet 13 is fixedly glued to the side of each air diaphragm 7a closest to the air chamber 6a using epoxy resin. The front end of each pneumatic heat exchanger tube 5 is a gas suction / spray end 5a connecting to the stator / rotor chamber 90. The rear end of the heat pipe 5 is the pressure transmission end 5b, which connects to the blower cavity 6a. The iron sheet 13 is elastically supported and connected to the inner wall of the cooling housing 1 by the support spring 10. A permanent magnet 3 is fixedly connected to the radial direction on the circumferential surface of the rotor tail end 4a of the permanent magnet rotor 4. The annular elastic diaphragm 7 is coaxially surrounded on the outer ring of the rotor tail end 4a. As the permanent magnet 3 rotates with the permanent magnet rotor 4, it corresponds to several iron sheets 13 arranged in a circular array. When the permanent magnet 3 corresponds to the iron sheet 13, the permanent magnet 3 forms a magnetic attraction force on the iron sheet 13. There are 6-12 isolation seats. The iron sheet 13 is made of soft iron material. The support spring 10 is made of stainless steel with an elastic coefficient of 5-10 N / mm to ensure that the blower diaphragm 7a can be quickly reset. The permanent magnet 3 is a rectangular neodymium iron boron magnet with a magnetic attraction force of 50-100 N, which is sufficient to drive the movement of the iron sheet.
[0032] Working principle:
[0033] In existing technologies, permanent magnet motor cooling often relies on external fans or independent water-cooling systems. However, the closed nature of the stator and rotor cavities at low speeds leads to poor internal air convection, causing hot air to accumulate and raising the temperature of the stator coils and rotor, reducing efficiency and shortening lifespan. During motor operation, coolant continuously flows into the clockwise end of the annular hollow liquid-cooled cavity 2 through the coolant inlet pipe 20. Then, the coolant flows counterclockwise through the entire annular hollow liquid-cooled cavity 2 and continuously flows out from the counterclockwise end of the annular hollow liquid-cooled cavity 2 through the coolant outlet pipe 21, thus continuously carrying away heat from the combined water and air cooling housing 1 and the outer ring of the stator coil 12. In typical motors, some heat from the stator coil 12 is continuously transferred to the stator-rotor cavity 90. Since the stator-rotor cavity 90 is a completely sealed chamber, heat is not easily dissipated, leading to heat accumulation.
[0034] This solution overcomes the above limitations through a unique pneumatic heat exchange mechanism. During the rotation of the permanent magnet rotor 4, the permanent magnet 3 rotates along with the permanent magnet rotor 4. The permanent magnet 3 will successively correspond to several iron pieces 13 arranged in a circular array. When the permanent magnet 3 corresponds to any iron piece 13, the permanent magnet 3 forms a magnetic attraction force on the iron piece 13. Under the action of the magnetic attraction force, the iron piece 13 pushes the blower diaphragm 7a to become convex 7aa and moves closer to the permanent magnet 3, thereby increasing the volume of the corresponding blower cavity 6a. As the permanent magnet rotor 4 rotates, when the iron piece 13 is misaligned with the permanent magnet 3, the iron piece 13 and the blower diaphragm 7a will reset under the elastic tension of the support spring 10, thereby restoring the volume of the blower cavity 6a.
[0035] The above process generates periodic air pressure, driving the airflow within the stator and rotor chambers. Each rotation of the permanent magnet rotor 4 causes a change in the volume of each blower chamber 6a, resulting in a periodic increase and decrease in air pressure within each blower chamber 6a. This periodically changing air pressure within each blower chamber 6a is transmitted through each pressure transmission end 5b to each pneumatic heat exchange tube 5, causing each pneumatic heat exchange tube 5 to periodically eject gas into and draw gas from the stator and rotor chamber 90 through the gas suction and spray ends 5a. This process results in a periodic increase in the heat exchange within the stator and rotor chamber 90. The air is periodically drawn in and expelled through the pneumatic heat exchange tube 5. The hot air undergoes efficient heat exchange with the coolant within the pneumatic heat exchange tube 5. The coolant absorbs heat through the tube wall, reducing the air temperature. The cooled air then re-enters the stator and rotor chamber, forming a cycle. This continuous and repeated flow significantly enhances the heat exchange efficiency of the pneumatic heat exchange tube 5, ultimately achieving efficient heat absorption of the gas within the stator and rotor chamber 90 and enhancing the heat exchange efficiency within the annular hollow liquid-cooled cavity 2. This design is particularly suitable for low-speed, high-load operating conditions and demonstrates significant innovation.
[0036] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A water-air combined cooling system for high-efficiency heat exchange of a permanent magnet motor, characterized in that: The system includes a water-air combined cooling housing (1), with a front end cover and a rear end cover encapsulated at both ends. The water-air combined cooling housing (1) encloses a stator-rotor cavity (90). A stator coil (12) and a permanent magnet rotor (4) are coaxially arranged inside the stator-rotor cavity (90). The stator coil (12) is coaxially heat-transferring and attached to the inner ring surface of the water-air combined cooling housing (1). The permanent magnet rotor (4) rotates coaxially within the area enclosed by the stator coil (12) and is coaxially mounted on a rotor shaft (81). The rotor shaft (81) rotates with the front end cover and the rear end cover via bearings. The water-air combined cooling housing (1) has an annular hollow liquid cooling cavity (2) inside the section where the stator coil (12) heats the cooling housing (1); several pneumatic heat exchange tubes (5) are arranged in a circumferential array inside the annular hollow liquid cooling cavity (2).
2. The water-air combined cooling system for high-efficiency heat exchange of a permanent magnet motor according to claim 1, characterized in that: The upper end of the annular hollow liquid cooling cavity (2) is separated by a partition wall (22). The partition wall (22) cuts off the upper end of the annular hollow liquid cooling cavity (2) and also includes a coolant inlet pipe (20) and a coolant outlet pipe (21). The coolant inlet pipe (20) and the coolant outlet pipe (21) are respectively connected to the annular hollow liquid cooling cavity (2) on the left and right sides of the partition wall (22). The coolant inlet pipe (20) flows into the clockwise end of the annular hollow liquid cooling cavity (2), flows through the entire annular hollow liquid cooling cavity (2) in a counterclockwise direction, and then flows out from the counterclockwise end of the annular hollow liquid cooling cavity (2) through the coolant outlet pipe (21).
3. The water-air combined cooling system for high-efficiency heat exchange of a permanent magnet motor according to claim 2, characterized in that: The outer wall of each of the pneumatic heat exchange tubes (5) maintains a gap with the inner and outer walls of the annular hollow liquid cooling cavity (2), and the outer wall of each pneumatic heat exchange tube (5) is immersed in the coolant in the annular hollow liquid cooling cavity (2).
4. The water-air combined cooling system for high-efficiency heat exchange of a permanent magnet motor according to claim 3, characterized in that: The extension direction of each of the pneumatic heat exchange tubes (5) is parallel to the axis of the water-air combined cooling housing (1).
5. The water-air combined cooling system for high-efficiency heat exchange of a permanent magnet motor according to claim 3, characterized in that: The water-air combined cooling housing (1) has a ring groove (6) coaxially arranged on the inner side of the tail, and also includes a ring elastic diaphragm (7) coaxially covering the ring groove (6), with the outline edge of the ring elastic diaphragm (7) sealingly matched with the edge outline of the ring groove (6). The annular groove (6) is provided with a plurality of isolation seats (8) arranged in a circular array. The annular elastic diaphragm (7) is fixed to the end of each isolation seat (8) by sealant, so that the plurality of isolation seats (8) divide the annular groove (6) into a plurality of blower chambers (6a) arranged in a circular array. The annular elastic diaphragm (7) covering each blower chamber (6a) is referred to as blower diaphragm (7a). A piece of iron sheet (13) is fixed on the side of each blower diaphragm (7a) near the blower chamber (6a). The front end of each pneumatic heat exchange tube (5) is a gas suction and spray end (5a) connected to the stator and rotor cavity (90), and the rear end of each pneumatic heat exchange tube (5) is a pressure transmission end (5b) connected to the blower cavity (6a). The iron sheet (13) is elastically supported and connected to the inner wall of the cooling housing (1) by a support spring (10); a permanent magnet (3) is fixedly connected to the circumferential surface of the rotor tail end (4a) of the permanent magnet rotor (4) in the radial direction; the annular elastic diaphragm (7) is coaxially surrounded on the outer ring of the rotor tail end (4a). During the rotation of the permanent magnet (3) with the permanent magnet rotor (4), the permanent magnet (3) corresponds to several iron sheets (13) arranged in a circular array. When the permanent magnet (3) corresponds to the iron sheet (13), the permanent magnet (3) forms a magnetic attraction force on the iron sheet (13).
6. The water-air combined cooling system for high-efficiency heat exchange of a permanent magnet motor according to claim 5, characterized in that: When the motor is running, the coolant flows into the clockwise end of the annular hollow liquid cooling cavity (2) through the coolant inlet pipe (20), and then flows through the entire annular hollow liquid cooling cavity (2) in a counterclockwise direction and flows out through the coolant outlet pipe (21) from the counterclockwise end of the annular hollow liquid cooling cavity (2), thereby continuously carrying away the heat of the water-air combined cooling housing (1) and the outer ring of the stator coil (12).
7. The water-air combined cooling system for high-efficiency heat exchange of a permanent magnet motor according to claim 6, characterized in that: During the rotation of the permanent magnet rotor (4), the permanent magnet (3) rotates with the permanent magnet rotor (4). The permanent magnet (3) will correspond to several iron pieces (13) arranged in a circular array. When the permanent magnet (3) corresponds to any iron piece (13), the permanent magnet (3) forms a magnetic attraction force on the iron piece (13), so that the iron piece (13) pushes the blower diaphragm (7a) to become convex (7aa) under the action of the magnetic attraction force and moves closer to the permanent magnet (3), thereby increasing the volume of the corresponding blower cavity (6a).
8. The water-air combined cooling system for high-efficiency heat exchange of a permanent magnet motor according to claim 7, characterized in that: During the rotation of the permanent magnet rotor (4), when the iron plate (13) is misaligned with the permanent magnet (3), the iron plate (13) and the blower diaphragm (7a) will reset under the elastic tension of the support spring (10), thereby restoring the volume of the blower cavity (6a).