Variable frequency outer rotor centrifugal fan

Abstract

The utility model discloses a variable frequency outer rotor centrifugal fan, including wind wheel, rotor, pivot, stator and end cover, and the middle part of end cover is equipped with hollow cylinder, and the inner wall of hollow cylinder is equipped with a ring of convex edge, and the upper end and the lower end of hollow cylinder form upper bearing chamber and lower bearing chamber respectively, and the first bearing is arranged in the upper bearing chamber, and the second bearing is arranged in the lower bearing chamber, and the pivot is rotatably connected with the hollow cylinder through the first bearing and the second bearing, and the contact place of pivot and the first bearing and the second bearing is provided with the integrally formed plastic coating layer. The utility model has the advantages of: improving the operation efficiency of fan in high frequency working condition, eliminating the bearing failure problem caused by electric corrosion, prolonging the service life of fan, solving the problem of shaft grinding, eliminating the bearing running, improving the assembly precision and concentricity, prolonging the service life of bearing and pivot, being provided with the labyrinth sealing structure, significantly improving the reliability and life in the harsh environment, the heat dissipation rib and the flow guide channel, optimizing the internal heat dissipation structure, and significantly reducing the temperature rise of fan.

Description

Technical Field

[0001] This utility model relates to the field of fan technology, and in particular to a variable frequency external rotor centrifugal fan. Background Technology

[0002] New energy storage systems such as flow batteries and flywheel energy storage are seeing large-scale applications. These systems generate significant heat accumulation during operation, and improper heat dissipation management can directly lead to malfunctions such as electrolyte decomposition and magnetic bearing instability, seriously threatening system safety. Therefore, centrifugal fans, as a core component of thermal management, must meet extremely stringent operating conditions: in flow battery energy storage scenarios, the electrolyte circulation pump and cooling fan are constantly exposed to highly corrosive gas environments (such as volatiles from acidic vanadium electrolytes), and their metal components face the risk of electrochemical corrosion; in flywheel energy storage vacuum chamber cooling systems, the fan needs to achieve ultra-high efficiency heat dissipation within a limited space and withstand the pulsating heat load caused by frequent charging and discharging. These special operating conditions place demands on the fan's material corrosion resistance, structural compactness, and speed regulation response speed that exceed conventional industrial standards.

[0003] External rotor structures, due to their direct impeller drive, offer advantages over internal rotor fans in terms of structural simplicity and high torque transmission efficiency. However, several key technological bottlenecks remain when applied to energy storage applications. Current designs commonly use traditional enameled wire windings for the stator. When the inverter outputs a high-frequency PWM waveform (typical carrier frequency 8-16kHz), the AC resistance of the wires increases dramatically due to the skin effect and proximity effect. Experimental data shows that at 10kHz operating conditions, the losses of conventional polyesterimide enameled wire windings increase by 45% compared to power frequency operation. This not only causes excessive stator temperature rise but also leads to a 5-7 percentage point decrease in overall efficiency. More seriously, high-frequency oscillating voltage can couple to the shaft through parasitic capacitance, inducing bearing current corrosion and ultimately causing raceway scaling failure. Summary of the Invention

[0004] This invention mainly solves the problem of bearing current corrosion caused by high-frequency oscillation voltage in existing variable frequency external rotor centrifugal fans, and provides a variable frequency external rotor centrifugal fan with a shaft plastic coating design that can avoid bearing failure caused by electro-corrosion.

[0005] The technical solution adopted by this utility model to solve its technical problem is a variable frequency external rotor centrifugal fan, including a fan wheel, a rotor, a rotating shaft, a stator, and an end cover. The fan wheel is fixedly mounted on the rotor. A hollow column is provided in the middle of the end cover. The upper end of the rotating shaft is fixedly connected to the fan wheel, and the lower end of the rotating shaft is rotatably mounted in the hollow column. The stator is sleeved on the outside of the hollow column. A raised edge is provided on the inner wall of the hollow column. The raised edge forms an upper bearing chamber and a lower bearing chamber at the upper and lower ends of the hollow column, respectively. A first bearing is provided in the upper bearing chamber, and a second bearing is provided in the lower bearing chamber. The rotating shaft is rotatably connected to the hollow column through the first bearing and the second bearing. An integrally formed plastic coating layer is provided at the contact point between the rotating shaft and the first bearing and the second bearing.

[0006] As a preferred embodiment of the above solution, the length of the plastic coating layer is greater than the thickness of the first bearing and the second bearing.

[0007] As a preferred embodiment of the above solution, the plastic coating layer is made of modified polyphenylene sulfide, and the thickness of the plastic coating layer is 0.70mm-0.80mm.

[0008] As a preferred embodiment of the above solution, the outer ring of the first bearing is bonded to the inner wall of the upper bearing chamber with anaerobic adhesive, the inner ring of the first bearing is interference-fitted with the shaft, a plastic gasket is provided between the upper end of the first bearing and the rotor, and a corrugated gasket is provided between the lower end of the first bearing and the upper end of the flange.

[0009] As a preferred embodiment of the above solution, the outer ring of the second bearing is fixed to the inner wall of the lower bearing chamber by a precision positioning ring, the inner ring of the second bearing is interference-fitted with the shaft, the lower end of the shaft is provided with a shaft retaining ring, the upper end of the second bearing abuts against the lower end of the flange, and a plastic gasket is provided between the lower end of the second bearing and the shaft retaining ring.

[0010] As a preferred embodiment of the above solution, the edge of the end cover is provided with several first end rings from the outside to the inside, and the edge of the rotor is provided with several second end rings from the outside to the inside. The first end rings and the second end rings are alternately arranged at the junction of the rotor and the end cover to form a labyrinth sealing structure.

[0011] As a preferred embodiment of the above scheme, the innermost end ring of the rotor is provided with a flow guiding channel, and the inner wall of the top surface of the rotor is provided with several heat dissipation fins.

[0012] As a preferred embodiment of the above solution, the heat dissipation fins are distributed around the center of the top surface of the rotor.

[0013] As a preferred embodiment of the above scheme, the windings in the stator are made of enameled wire coated with polyamide-imide composite polyesterimide varnish.

[0014] As a preferred embodiment of the above solution, the lower end of the hollow column is provided with a through end cap, and a sealing ring and a dust cover are provided sequentially from top to bottom at the lower end of the hollow column.

[0015] The advantages of this invention are: Optimization of the variable frequency enameled wire improves the operating efficiency of the fan under high-frequency conditions; the shaft plastic coating design completely eliminates bearing failure caused by electro-corrosion, effectively extending the fan's lifespan and ensuring stable operation under harsh environments; the dual-bearing design uses anaerobic adhesive and precision positioning rings to fix the outer bearing rings, and an interference fit to fix the shaft and inner bearing rings, solving the shaft wear problem, eliminating bearing race slippage, improving assembly accuracy and concentricity, and extending the lifespan of the bearings and shaft; a labyrinth seal structure is provided on the rotor and end cover edges, effectively preventing dust, moisture, and salt spray from entering the motor and damaging the bearings and enameled wires, significantly improving reliability and lifespan in harsh environments; the rotor is equipped with heat dissipation fins and flow channels, optimizing the internal heat dissipation structure, significantly reducing fan temperature rise, and improving reliability and lifespan under high load / high temperature environments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a variable frequency external rotor centrifugal fan.

[0017] Figure 2 This is a schematic diagram of the exploded structure of a variable frequency external rotor centrifugal fan.

[0018] Figure 3 This is a cross-sectional structural diagram of a variable frequency external rotor centrifugal fan.

[0019] Figure 4 for Figure 3 A magnified view of a portion of region A in the middle.

[0020] Figure 5 for Figure 3 A magnified view of a portion of region B in the middle.

[0021] Figure 6 for Figure 3 A magnified view of a portion of region C.

[0022] Figure 7 This is a schematic diagram of the rotor.

[0023] 1-Wind wheel 2-Rotor 3-Shaft 4-Stator 5-End cover 6-Hollow cylinder 7-First bearing 8-Wave gasket 9-Plastic gasket 10-Raised edge 11-Plastic coating 12-Second bearing 13-Precision positioning ring 14-Shaft retaining ring 15-Sealing ring 16-Dust cover 17-First end ring 18-Second end ring 19-Guide channel 20-Heat dissipation fin Detailed Implementation

[0024] The technical solution of this utility model will be further described below through embodiments and in conjunction with the accompanying drawings.

[0025] Example: This embodiment describes a variable frequency external rotor centrifugal fan, such as... Figure 1 and Figure 2 As shown, the device includes a wind turbine 1, a rotor 2, a shaft 3, a stator 4, and an end cover 5. The wind turbine 1 is fixedly mounted on the rotor 2. A hollow column 6 is located in the middle of the end cover 5. The upper end of the shaft 3 is fixedly connected to the wind turbine 1, and the lower end of the shaft 3 is rotatably mounted in the hollow column 6. The stator 4 is sleeved on the hollow column 6. The windings in the stator are made of enameled wire coated with polyamide-imide composite polyesterimide varnish. Polyamide-imide composite polyesterimide varnish can withstand variable frequency pulse voltage, increasing the withstand voltage by 80% compared to conventional enameled wire, enabling the fan to maintain an efficiency of ≥92% under 10kHz PWM conditions, an improvement of 7 percentage points compared to traditional enameled wire.

[0026] like Figures 3 to 5As shown, the inner wall of the hollow cylinder 6 is provided with a raised edge 10. The raised edge 10 forms an upper bearing chamber and a lower bearing chamber at the upper and lower ends of the hollow cylinder 6, respectively. A first bearing 7 is installed in the upper bearing chamber, and a second bearing 12 is installed in the lower bearing chamber. The rotating shaft 3 is rotatably connected to the hollow cylinder 6 through the first bearing 7 and the second bearing 12. An integrally formed plastic coating layer 11 is provided at the contact point between the rotating shaft 3 and the first bearing 7 and the second bearing 12. Specifically, the length of the plastic coating layer is greater than the thickness of the first bearing and the second bearing. The plastic coating layer is made of modified polyphenylene sulfide, and the thickness of the plastic coating layer is 0.70mm-0.80mm. The outer ring of the first bearing 7 is bonded to the inner wall of the upper bearing chamber with anaerobic adhesive. The inner ring of the first bearing 7 is interference-fitted with the rotating shaft 3. A plastic gasket 9 is provided between the upper end of the first bearing 7 and the rotor 2, and a corrugated gasket 8 is provided between the lower end of the first bearing 7 and the upper end of the raised edge 10. The outer ring of the second bearing 12 is fixed to the inner wall of the lower bearing chamber via a precision positioning ring 13. The inner ring of the second bearing 12 is interference-fitted with the shaft 3. A shaft retaining ring 14 is provided at the lower end of the shaft 3. The upper end of the second bearing 12 abuts against the lower end of the flange 10. Two plastic gaskets 9 are provided between the lower end of the second bearing 13 and the shaft retaining ring. In this embodiment, the modified polyphenylene sulfide has a dielectric strength >25kV / mm and a coefficient of friction <0.15. The high dielectric strength can effectively block the shaft current path, and the low coefficient of friction can avoid wear of the plastic coating layer. At the same time, plastic gaskets 8 are added between the bearing 3 and the shaft retaining ring 14 to enhance its insulation performance. The plastic coating layer 11 extends to the inner side of the bearing chamber to form a fully enclosed barrier, completely isolating the electro-corrosion circuit. Accelerated life tests show that, under the same PWM operating conditions, the bearing life of the plastic-coated shaft fan is extended to 4.2 times that of the conventional design. In addition, the first and second bearings are fixed to the bearing housing by anaerobic adhesive and precision positioning rings, respectively. An interference fit is used to fix the shaft and the inner ring of the bearing, which solves the shaft grinding problem, eliminates bearing race slippage, improves assembly accuracy and concentricity, and extends the life of the bearing and shaft.

[0027] Furthermore, the lower end of the hollow column 6 is provided with a through end cap 5, and a sealing ring 15 and a dust cover 16 are provided sequentially from top to bottom at the lower end of the hollow column 6.

[0028] like Figure 6 As shown, the edge of the end cover 5 is provided with several first end rings 17 arranged sequentially from the outside to the inside, and the edge of the rotor 2 is provided with several second end rings 18 arranged sequentially from the outside to the inside. The first end rings 17 and the second end rings 18 are staggered at the junction of the rotor and the end cover to form a labyrinth sealing structure. In this embodiment, there are two first end rings and two second end rings. The two first end rings and the two second end rings are staggered to form a double labyrinth structure, which effectively prevents dust, water vapor, and salt spray from entering the motor and damaging the bearings and enameled wires, significantly improving reliability and lifespan in harsh environments.

[0029] like Figure 7As shown, the innermost second end ring 18 of rotor 3 has a ring of flow guiding channels 19 on its inner wall, and the top surface of rotor 3 has several heat dissipation fins 20, which are distributed around the center of the top surface of rotor 3. When the fan is running, the air inside the rotor absorbs heat from the rotor through the heat dissipation fins and diffuses to the space at the end cover through the flow guiding channels, thereby achieving internal heat dissipation, reducing the temperature rise of the fan, and improving the reliability and lifespan under high load and high temperature environments.

[0030] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A variable frequency external rotor centrifugal fan, comprising a fan wheel, a rotor, a shaft, a stator, and an end cover, wherein the fan wheel is fixedly mounted on the rotor, a hollow column is provided in the middle of the end cover, the upper end of the shaft is fixedly connected to the fan wheel, and the lower end of the shaft is rotatably mounted in the hollow column, and the stator is sleeved outside the hollow column, characterized in that: The hollow cylinder has a raised edge on its inner wall. The raised edge forms an upper bearing chamber and a lower bearing chamber at the upper and lower ends of the hollow cylinder, respectively. A first bearing is installed in the upper bearing chamber and a second bearing is installed in the lower bearing chamber. The rotating shaft is rotatably connected to the hollow cylinder through the first and second bearings. An integrally formed plastic coating layer is provided at the contact point between the rotating shaft and the first and second bearings.

2. The variable frequency external rotor centrifugal fan according to claim 1, characterized in that: The length of the plastic coating layer is greater than the thickness of the first bearing and the second bearing.

3. The variable frequency external rotor centrifugal fan according to claim 1, characterized in that: The plastic coating layer is made of modified polyphenylene sulfide, and the thickness of the plastic coating layer is 0.70mm-0.80mm.

4. The variable frequency external rotor centrifugal fan according to claim 1, characterized in that: The outer ring of the first bearing is bonded to the inner wall of the upper bearing chamber with anaerobic adhesive. The inner ring of the first bearing is interference-fitted with the shaft. A plastic gasket is provided between the upper end of the first bearing and the rotor. A corrugated gasket is provided between the lower end of the first bearing and the upper end of the flange.

5. The variable frequency external rotor centrifugal fan according to claim 1, characterized in that: The outer ring of the second bearing is fixed to the inner wall of the lower bearing chamber by a precision positioning ring. The inner ring of the second bearing is interference-fitted with the shaft. The lower end of the shaft is provided with a shaft retaining ring. The upper end of the second bearing abuts against the lower end of the flange. A plastic gasket is provided between the lower end of the second bearing and the shaft retaining ring.

6. The variable frequency external rotor centrifugal fan according to claim 1, characterized in that: The edge of the end cover is provided with several first end rings from the outside to the inside, and the edge of the rotor is provided with several second end rings from the outside to the inside. The first end rings and the second end rings are alternately arranged at the junction of the rotor and the end cover to form a labyrinth sealing structure.

7. The variable frequency external rotor centrifugal fan according to claim 1, characterized in that: The innermost end ring of the rotor has a flow channel on its inner wall, and the top surface of the rotor has several heat dissipation fins on its inner wall.

8. The variable frequency external rotor centrifugal fan according to claim 7, characterized in that: The heat dissipation fins are distributed around the center of the top surface of the rotor.

9. The variable frequency external rotor centrifugal fan according to claim 1, characterized in that: The windings in the stator are made of enameled wire coated with polyamide-imide composite polyesterimide varnish.

10. The variable frequency external rotor centrifugal fan according to claim 1, characterized in that: The lower end of the hollow column is provided with a through end cap, and a sealing ring and a dust cover are provided sequentially from top to bottom at the lower end of the hollow column.

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