High-power industrial fan permanent magnet motor stator potting heat dissipation process

Abstract

The invention discloses a stator encapsulation heat dissipation process for a high-power industrial fan permanent magnet motor, and the process is characterized in that the process comprises the following steps: S1, pretreatment: carrying out the cleaning, drying and preheating of a stator iron core of a permanent magnet motor and a winding embedded in the stator iron core; s2, assembling a mold: placing the pretreated stator assembly in a potting mold, and enabling an annular potting cavity to be formed between the outer circular surface of the stator core and the inner wall of the mold; s3, vacuum potting: in a vacuum environment, injecting a uniformly mixed liquid-state potting adhesive into the potting cavity until the potting adhesive completely covers the end part and the in-slot part of the winding; s4, step-by-step curing: carrying out step-by-step heating curing treatment on the stator assembly which is subjected to encapsulation to form a solid-sealed heat conductor which is tightly combined with the stator iron core and the winding; and S5, post-processing: after curing is completed, demolding is performed, and the surface of the stator is cleaned. Through the innovative structural design and process method, the heat dissipation efficiency, the mechanical reliability and the environmental tolerance are improved.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet motor technology, and in particular to a process for potting and heat dissipation of the stator of a high-power industrial fan permanent magnet motor. Background Technology

[0002] Industrial fans, as a wide-ranging air circulation and regulation device, are widely used in factory ventilation, warehousing and logistics, sports stadiums, and other fields. Their core drive component—the high-power permanent magnet synchronous motor—has become the mainstream choice due to its high efficiency, high power density, and excellent speed regulation performance. However, with the continuous increase in power levels and the trend towards compact designs, the heat dissipation problem of the motor has become increasingly prominent, becoming a key technical bottleneck restricting the continuous improvement of its reliability, lifespan, and performance.

[0003] During operation, the copper losses in the stator windings and the iron losses in the core of a permanent magnet motor are the main sources of heat. For high-power industrial fan motors, which often operate continuously at low to medium speeds and high torque, the heat generated is large and concentrated. If this heat cannot be dissipated effectively and promptly, the winding temperature will rise sharply, accelerating the thermal aging of the insulation material, increasing the risk of demagnetization of the magnets, and in severe cases, even causing insulation breakdown and motor burnout. Therefore, an efficient and reliable heat dissipation design is crucial.

[0004] Currently, the main heat dissipation solutions for this type of motor are as follows: Natural air cooling and forced air cooling: These methods are simple in structure and low in cost. However, the airflow generated by the fan itself is limited, resulting in low heat dissipation efficiency, and the fan itself consumes energy. In harsh industrial environments such as dust and humidity, the fan blades are prone to accumulating dirt, further reducing heat dissipation efficiency and potentially introducing external impurities into the motor.

[0005] Water / oil cooling of the casing: Cooling channels are set inside the casing, and heat is removed by circulating liquid. This method has strong heat dissipation capacity, but the system is complex, adding components such as water pumps, pipelines, and seals. There is a risk of leakage, and the maintenance cost is high. It is not suitable for all industrial fan applications with strict requirements for cost, reliability, and ease of maintenance.

[0006] Conventional potting or varnishing processes involve impregnating or simply filling the stator windings with ordinary insulating varnish or low thermal conductivity resin. The main purpose is to enhance electrical insulation and provide moisture and shock resistance. However, the materials used generally have low thermal conductivity (typically below 0.5 W / (m·K)), offering limited contribution to improving the heat conduction path between the windings and the housing, and failing to effectively reduce the temperature of the winding hotspots. Furthermore, air bubbles are easily left behind during the process, creating localized thermal resistance.

[0007] Specifically, in the stator heat dissipation path, heat generated from the internal windings must sequentially pass through the winding insulation layer, the slot gaps, and the stator core laminations before finally being transferred to the external housing for dissipation. The air gaps between the windings (especially at the ends) and the core and housing are the main sources of thermal resistance. Traditional structural designs make it difficult to eliminate this thermal resistance, leading to heat accumulation in the windings.

[0008] Therefore, existing heat dissipation solutions are either inefficient, overly complex, unreliable, or fail to effectively address the critical heat conduction bottleneck between the windings and the casing. Developing a heat dissipation process that significantly enhances the internal thermal conductivity of the stator, is technologically reliable, has a compact structure, and is suitable for high-power industrial fan permanent magnet motors has significant engineering practical value and meets real-world needs. This invention aims to propose a targeted stator potting heat dissipation process to fill the aforementioned technological gaps. Summary of the Invention

[0009] This invention proposes a stator potting and heat dissipation process for high-power industrial fan permanent magnet motors, which solves the aforementioned problems existing in the use of existing technologies.

[0010] The technical solution of this invention is implemented as follows: A stator potting and heat dissipation process for high-power industrial fan permanent magnet motors, characterized by comprising the following steps: S1. Pretreatment: Cleaning, drying and preheating of the stator core and windings embedded therein of the permanent magnet motor; S2. Mold assembly: Place the pre-treated stator assembly into the potting mold, and form an annular potting cavity between the outer surface of the stator core and the inner wall of the mold. S3. Vacuum potting: In a vacuum environment, a uniformly mixed liquid potting compound is injected into the potting cavity until the potting compound completely covers the end of the winding and the groove portion. S4. Stepped curing: The stator assembly that has been potted is subjected to a stepped heating curing process to form a solidified heat conductor that is tightly bonded to the stator core and windings. S5. Post-processing: After curing, demold and clean the stator surface.

[0011] Preferably, in step S1, the preheating temperature is 60℃-85℃, and the preheating time is not less than 2 hours.

[0012] Preferably, in step S2, the radial thickness of the potting cavity is 3%-8% of the outer diameter of the stator core.

[0013] Preferably, in step S3, the potting compound used is a high thermal conductivity epoxy resin composite material with a thermal conductivity of not less than 1.5 W / (m·K), and is degassed before injection; the absolute pressure of the vacuum environment is not greater than 100 Pa.

[0014] Preferably, the high thermal conductivity epoxy resin composite material comprises the following components by weight: 100 parts epoxy resin matrix, 30-50 parts curing agent, and 150-250 parts of aluminum nitride and alumina mixed thermally conductive filler with particle size distribution.

[0015] Preferably, in step S4, the specific steps of the stepped temperature curing treatment are as follows: first, maintain at 60℃-75℃ for 1-2 hours, then maintain at 90℃-105℃ for 2-4 hours, and finally maintain at 120℃-135℃ for 3-5 hours.

[0016] Preferably, in step S3, the potting is performed by multi-point pressure injection from the bottom of the stator, with an injection pressure of 0.2-0.5 MPa.

[0017] Preferably, in step S2, a spiral metal thermally conductive bushing that contacts the outer circular surface of the stator core is pre-placed in the potting cavity, and the potting adhesive fills the space between the thermally conductive bushing and the inner wall of the mold.

[0018] The metal thermally conductive bushing is made of copper or aluminum alloy, and its inner wall is bonded to the outer circular surface of the stator core through a thermally conductive insulating layer.

[0019] A permanent magnet motor stator is prepared by the stator potting and heat dissipation process described above, wherein the solidified heat conductor is wrapped around the outside of the stator core and windings.

[0020] In summary, the beneficial effects of the present invention are as follows: The stator potting and heat dissipation process for high-power industrial fan permanent magnet motors provided by this invention systematically solves the key problems of low heat dissipation efficiency, system complexity, and insufficient reliability in existing technologies through innovative structural design and process methods. It mainly has the following significant effects and benefits: 1. Improve heat dissipation efficiency and motor thermal performance Constructing a highly efficient axial-radial three-dimensional heat conduction network: By forming a highly thermally conductive solid seal within the outer circumferential potting cavity and utilizing the axial guidance of a spiral metal bushing (if employed), the heat path, which traditionally relies primarily on radial conduction, is expanded into a highly efficient three-dimensional heat dissipation channel that combines axial and radial conduction. This significantly shortens the heat conduction path from "hot spot" areas such as the winding ends to the external cooling environment.

[0021] Significantly reduces thermal resistance at critical interfaces: The high thermal conductivity potting compound completely fills all air gaps between the winding and the core, and between the core and the housing (through the solid sealant) in a vacuum environment. The low thermal conductivity gas medium is replaced with a high thermal conductivity material (thermal conductivity ≥1.5 W / (m·K)), which fundamentally eliminates the main thermal barrier and allows the heat generated by the winding to be transferred to the housing for dissipation more smoothly.

[0022] Direct effects: It can effectively reduce the temperature rise of the stator winding (especially the temperature of the end hot spots) by more than 20%, allowing the motor to operate stably at a higher power density, or extending the motor life without reducing performance.

[0023] 2. Significantly enhances the reliability and environmental adaptability of the motor. Integrated reinforcement and protection: The solid seal tightly bonds the windings and iron core into a solid whole, which greatly improves the mechanical strength of the stator assembly and can effectively resist the vibration and impact during fan operation, preventing winding loosening and insulation wear.

[0024] Superior sealing and protection: The potting compound completely covers the windings, providing excellent moisture-proof, dust-proof, corrosion-proof and condensation-proof capabilities, enabling the motor to adapt to harsh industrial environments such as high humidity and high dust, reducing failure rate and maintenance requirements.

[0025] Protecting permanent magnets: By effectively controlling the temperature rise of the windings, the internal ambient temperature of the motor is indirectly reduced, mitigating the risk of irreversible demagnetization of the rotor permanent magnets due to high temperature, and ensuring the stability of the magnetic performance of the motor during long-term operation.

[0026] 3. Optimize production processes and product quality. High process reliability: Vacuum potting combined with stepped curing process ensures full flow and filling of potting compound in complex structures, eliminates internal bubbles and defects to the greatest extent, ensures the integrity of thermal interface, and results in good product consistency.

[0027] Simplified subsequent systems: Since the stator's own heat dissipation capacity is fundamentally enhanced, the reliance on external forced air cooling or complex liquid cooling systems can be reduced or even eliminated, simplifying the overall structure and reducing system costs and potential failure points.

[0028] 4. Achieve an optimal balance between structure and performance. Compact structure: The potting layer thickness is optimized to achieve maximum heat dissipation gain within a limited space without significantly increasing the motor size.

[0029] Maximizing material efficiency: By adopting a composite thermally conductive filler formulation with particle size distribution, the optimal configuration of thermal conductivity is achieved while ensuring the flowability and insulation of the potting compound, resulting in high cost-effectiveness.

[0030] In summary, this invention is not only a heat dissipation process, but also a systematic thermal management solution. Starting from the source of heat generation (the windings), it reconstructs the internal heat conduction system of the motor through material and process innovation, achieving a synergistic leap in heat dissipation efficiency, mechanical reliability, and environmental tolerance. This provides a solid technical guarantee for the high-performance, high-reliability, and long-life operation of high-power industrial fan permanent magnet motors. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Example This embodiment discloses a stator potting and heat dissipation process for a high-power industrial fan permanent magnet motor, characterized by the following steps: S1. Pretreatment: Cleaning, drying and preheating of the stator core and windings embedded therein of the permanent magnet motor; S2. Mold assembly: Place the pre-treated stator assembly into the potting mold, and form an annular potting cavity between the outer surface of the stator core and the inner wall of the mold. S3. Vacuum potting: In a vacuum environment, a uniformly mixed liquid potting compound is injected into the potting cavity until the potting compound completely covers the end of the winding and the groove portion. S4. Stepped curing: The stator assembly that has been potted is subjected to a stepped heating curing process to form a solidified heat conductor that is tightly bonded to the stator core and windings. S5. Post-processing: After curing, demold and clean the stator surface.

[0033] Preferably, in step S1, the preheating temperature is 60℃-85℃, and the preheating time is not less than 2 hours.

[0034] Preferably, in step S2, the radial thickness of the potting cavity is 3%-8% of the outer diameter of the stator core.

[0035] Preferably, in step S3, the potting compound used is a high thermal conductivity epoxy resin composite material with a thermal conductivity of not less than 1.5 W / (m·K), and is degassed before injection; the absolute pressure of the vacuum environment is not greater than 100 Pa.

[0036] Preferably, the high thermal conductivity epoxy resin composite material comprises the following components by weight: 100 parts epoxy resin matrix, 30-50 parts curing agent, and 150-250 parts of aluminum nitride and alumina mixed thermally conductive filler with particle size distribution.

[0037] Preferably, in step S4, the specific steps of the stepped temperature curing treatment are as follows: first, maintain at 60℃-75℃ for 1-2 hours, then maintain at 90℃-105℃ for 2-4 hours, and finally maintain at 120℃-135℃ for 3-5 hours.

[0038] Preferably, in step S3, the potting is performed by multi-point pressure injection from the bottom of the stator, with an injection pressure of 0.2-0.5 MPa.

[0039] Preferably, in step S2, a spiral metal thermally conductive bushing that contacts the outer circular surface of the stator core is pre-placed in the potting cavity, and the potting adhesive fills the space between the thermally conductive bushing and the inner wall of the mold.

[0040] The metal thermally conductive bushing is made of copper or aluminum alloy, and its inner wall is bonded to the outer circular surface of the stator core through a thermally conductive insulating layer.

[0041] A permanent magnet motor stator is prepared by the stator potting and heat dissipation process described above, wherein the solidified heat conductor is wrapped around the outside of the stator core and windings.

[0042] Example The stator potting and heat dissipation process for high-power industrial fan permanent magnet motors described in this invention will be explained in detail below with reference to specific embodiments: Example 1: Basic Encapsulation Heat Dissipation Process This embodiment takes the stator of an industrial fan permanent magnet synchronous motor with a rated power of 22kW and a stator outer diameter of 320mm as an example.

[0043] 1. Preprocessing (S1) The stator assembly (including stator core 1 and winding 2) that has been wound, embedded and initially bound is blown with compressed air to remove dust and copper shavings.

[0044] Place the stator assembly in an oven and preheat it at 80°C for 3 hours to completely remove internal moisture and ensure uniform temperature.

[0045] 2. Mold assembly (S2) The preheated stator assembly is vertically placed into a specially made cylindrical steel potting mold. The inner diameter of the mold is precisely calculated to form a uniform annular potting cavity 3 between it and the outer circular surface of the stator core 1. In this embodiment, the radial thickness of the cavity is designed to be 12mm (approximately 3.75% of the stator outer diameter).

[0046] A sealing ring is placed between the bottom of the stator assembly and the mold to ensure no leakage during potting.

[0047] 3. Vacuum potting (S3) The entire mold assembly was moved into the working chamber of the vacuum filling equipment.

[0048] Start the vacuum pump to pump the absolute pressure inside the chamber to 80 Pa and maintain it.

[0049] Preparation of potting compound: This embodiment uses a high thermal conductivity epoxy resin composite material, which is composed of the following components in parts by weight, pre-degassed in a planetary mixer: 100 parts of bisphenol A type epoxy resin (EPIKOTE 828), 40 parts of modified amine curing agent (JEFFAMINE D-230), and 180 parts of a mixed thermally conductive filler consisting of spherical alumina with an average particle size of 15 μm and flaky aluminum nitride with a mass ratio of 7:3. The thermal conductivity of the mixed compound is approximately 1.8 W / (m·K).

[0050] Under vacuum, the degassed potting compound is slowly injected into the potting cavity 3 at a constant pressure of 0.3 MPa through the injection port at the bottom of the mold. During the injection process, the compound can be seen rising steadily, fully wetting the ends of the winding 2, and penetrating into the groove.

[0051] Stop applying the adhesive once the adhesive completely covers the ends of the winding and reaches the predetermined height (slightly above the iron core).

[0052] 4. Stepped curing (S4) After potting, let it stand in a vacuum environment for 30 minutes to allow the adhesive to further penetrate and remove any remaining tiny air bubbles.

[0053] Then, the process involves temperature-increasing curing: First stage: Transfer the mold to a curing oven, heat it to 70℃ at 1℃ / min, and keep it at that temperature for 2 hours to allow the colloid to initially gel.

[0054] Second stage: Continue to increase the temperature to 100℃ at a rate of 0.5℃ / min, and hold for 3 hours to complete the main cross-linking reaction.

[0055] The third stage: finally, the temperature is raised to 130℃ and held for 4 hours to achieve post-curing, so that the material performance reaches the optimal level.

[0056] Let it cool naturally to below 60°C.

[0057] 5. Post-processing (S5) Remove the mold from the oven, demold, and obtain the solidified stator. The solidified heat conductor 4 is tightly bonded to the stator core 1 and winding 2, and has a smooth appearance.

[0058] Clean up any excess adhesive from the stator leads and mating surfaces.

[0059] Effect verification: The stator processed using the method described in this embodiment was assembled into a motor. Under the same load (22kW, continuous operation), a temperature rise test was conducted to compare it with that of a motor of the same specification using conventional impregnated insulating varnish (thermal conductivity approximately 0.2 W / (m·K)). Monitoring was performed using an infrared thermal imager and embedded thermocouples. The results showed that the stator winding hot spot temperature under the method of this invention was 102℃, while the winding hot spot temperature under the conventional method was 138℃. The method of this invention reduces the winding hot spot temperature rise by approximately 26%, demonstrating a significant heat dissipation effect.

[0060] Example 2: Enhanced potting heat dissipation process with integrated metal thermally conductive bushing This embodiment takes a long stator motor with a rated power of 37kW, a stator outer diameter of 380mm, and higher requirements for axial heat dissipation as an example.

[0061] 1. Preprocessing (S1) The operation is the same as in Example 1, with a preheating temperature of 85°C and a time of 3.5 hours.

[0062] 2. Mold Assembly (S2) – Key Improvement Steps A layer of high thermal conductivity insulating adhesive (such as boron nitride-filled silicone adhesive) with a thickness of about 0.2 mm is uniformly coated on the outer circular surface of the stator core 1 to form a thermally conductive insulating layer 6.

[0063] While still hot, a pre-machined T2 copper spiral thermally conductive bushing 5 (wall thickness 1.5mm, spiral flow channel lead 60mm) is fitted over the stator core 1, ensuring a tight fit through the thermally conductive insulation layer 6. This bushing 5 also serves as the potting inner mold.

[0064] The assembled "stator-bushing" assembly is placed into the mold, at which point the potting cavity 3 is located between the outer wall of the bushing 5 and the inner wall of the mold.

[0065] 3. Vacuum potting (S3) The vacuum environment control is the same as in Example 1 (absolute pressure ≤ 80 Pa).

[0066] The potting compound uses a higher thermal conductivity formulation: 100 parts epoxy resin, 45 parts acid anhydride curing agent, and 220 parts graded mixed thermally conductive filler (micron-sized alumina, submicron-sized aluminum nitride, and a small amount of nano zinc oxide). The measured thermal conductivity is 2.2 W / (m·K).

[0067] Multi-point bottom pressure injection is used with a pressure of 0.4MPa to ensure that the adhesive is quickly and evenly filled in the complex flow channels outside the spiral bushing 5.

[0068] 4. Stepped curing (S4) The curing curve was optimized as follows: 75℃ / 2h → 105℃ / 3.5h → 135℃ / 5h.

[0069] 5. Post-processing (S5) The operation is the same as in Example 1. The final solidified heat conductor 4 has a continuous metal spiral heat-conducting bushing 5 embedded inside.

[0070] Effect verification: A comparative test was conducted with a 37kW stator of the same specifications using only the process of Example 1 (without metal bushings). Under a continuous load of 37kW, the hot spot temperature of the stator winding using this Example 2 was only 108℃, while the hot spot temperature of the stator using the process of Example 1 was 119℃, and the hot spot temperature of the stator using the traditional process exceeded 155℃. This Example 2 not only maintains excellent radial heat dissipation capability, but also efficiently guides the heat from the ends to the middle and both ends of the stator along the spiral path through the axial "thermosiphon" effect of the copper bushing, achieving a more uniform three-dimensional heat dissipation of the temperature field, further reducing the hot spot temperature by 9.2%. At the same time, the addition of the copper bushing significantly enhances the overall structural rigidity of the stator assembly.

[0071] The above embodiments fully demonstrate the effectiveness, flexibility, and significant performance improvement of the process of the present invention. Those skilled in the art can adaptively adjust parameters such as the potting compound formulation, cavity thickness, curing regime, and whether or not to add a metal bushing, within the scope defined by the claims of the present invention, according to the specific motor's power, size, and heat dissipation requirements, all of which can achieve the beneficial effects expected by the present invention.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A stator potting and heat dissipation process for a high-power industrial fan permanent magnet motor, characterized in that, Includes the following steps: S1. Pretreatment: Cleaning, drying and preheating of the stator core and windings embedded therein of the permanent magnet motor; S2. Mold assembly: Place the pre-treated stator assembly into the potting mold, and form an annular potting cavity between the outer surface of the stator core and the inner wall of the mold. S3. Vacuum potting: In a vacuum environment, a uniformly mixed liquid potting compound is injected into the potting cavity until the potting compound completely covers the end of the winding and the groove portion. S4. Stepped curing: The stator assembly that has been potted is subjected to a stepped heating curing process to form a solidified heat conductor that is tightly bonded to the stator core and windings. S5. Post-processing: After curing, demold and clean the stator surface.

2. The stator potting and heat dissipation process according to claim 1, characterized in that: In step S1, the preheating temperature is 60℃-85℃, and the preheating time is not less than 2 hours.

3. The stator potting and heat dissipation process according to claim 1, characterized in that: In step S2, the radial thickness of the potting cavity is 3%-8% of the outer diameter of the stator core.

4. The stator potting and heat dissipation process according to claim 1, characterized in that: In step S3, the potting compound used is a high thermal conductivity epoxy resin composite material with a thermal conductivity of not less than 1.5 W / (m·K), and it is degassed before injection; the absolute pressure of the vacuum environment is not greater than 100 Pa.

5. The stator potting and heat dissipation process according to claim 4, characterized in that: The high thermal conductivity epoxy resin composite material comprises the following components by weight: 100 parts epoxy resin matrix, 30-50 parts curing agent, and 150-250 parts of aluminum nitride and aluminum oxide mixed thermally conductive filler with particle size distribution.

6. The stator potting and heat dissipation process according to claim 1, characterized in that: In step S4, the specific steps of the stepped temperature curing process are as follows: first, maintain at 60℃-75℃ for 1-2 hours, then maintain at 90℃-105℃ for 2-4 hours, and finally maintain at 120℃-135℃ for 3-5 hours.

7. The stator potting and heat dissipation process according to claim 1, characterized in that: In step S3, the stator is filled by multi-point pressure injection from the bottom of the stator, with an injection pressure of 0.2-0.5 MPa.

8. The stator potting and heat dissipation process according to claim 1, characterized in that: In step S2, a spiral metal thermally conductive bushing that contacts the outer circular surface of the stator core is pre-placed in the potting cavity, and the potting adhesive fills the space between the thermally conductive bushing and the inner wall of the mold.

9. The stator potting and heat dissipation process according to claim 8, characterized in that: The metal thermally conductive bushing is made of copper or aluminum alloy, and its inner wall is bonded to the outer circular surface of the stator core through a thermally conductive insulating layer.