High-protection outer rotor DC motor

Abstract

The high-protection outer rotor DC motor comprises a stator assembly and a rotor assembly, a shell of the rotor assembly is rotationally arranged outside the stator assembly, a first annular groove is formed in the bottom end of the stator assembly, a second annular groove is formed in the inner wall of the bottom end of the shell, and the first annular groove and the second annular groove are arranged in a crossed mode; the stator assembly comprises a packaging part, the electric control board is embedded in the packaging part, and a dustproof cover is arranged on the upper surface of the stator assembly and located above the shaft of the rotor assembly. The dustproof and waterproof effects are improved, a good working environment is provided for internal components, and the service life is prolonged.

Description

Technical Field

[0001] This utility model relates to the field of motor technology, and in particular to a high-protection external rotor DC motor. Background Technology

[0002] The widespread application of traditional DC motors in industrial fields has driven higher requirements for motor performance and reliability. However, current traditional DC motors on the market have significant shortcomings in protection design, with generally low protection levels, making them unable to effectively resist the intrusion of external environmental factors. In actual operation, motors are susceptible to environmental factors such as dust, moisture, and oil, and after long-term operation, critical components such as internal control boards and bearings are prone to damage.

[0003] Chinese Patent Publication No. CN202323072990.3, Publication Date: May 14, 2024, discloses a Chinese patent entitled "Motor and Washing Equipment," which includes a cover and an electrical control board. The cover is connected to a surrounding edge, allowing it to cover the opening structure. This combination of the cover and the surrounding edge defines an installation space, accommodating the electrical control board and preventing it from being exposed, thus improving protection. While this device protects the electrical control board, it does not effectively protect other components inside the motor and requires a separately designed cover, consuming space. Utility Model Content

[0004] This invention provides a high-protection external rotor DC motor. By setting mutually intersecting first and second annular grooves, the dustproof and waterproof effect is improved, providing a good working environment for internal components and extending service life.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a high-protection external rotor DC motor, comprising a stator assembly and a rotor assembly, wherein the housing of the rotor assembly is rotatably disposed outside the stator assembly, the bottom end of the stator assembly is provided with a first annular groove, and the inner wall of the bottom end of the housing is provided with a second annular groove, the first annular groove and the second annular groove being arranged intersecting each other; the stator assembly includes an encapsulation part, the electronic control board is embedded in the encapsulation part, and a dust cover is provided on the upper surface of the stator assembly above the shaft of the rotor assembly.

[0006] Preferably, the inner wall of the first annular groove is disposed within the second annular groove, and the outer wall of the second annular groove is disposed within the first annular groove. This nested design forms a multi-layered protective barrier, i.e., a labyrinthine waterproof structure, effectively preventing the intrusion of dust and moisture. The intersecting annular groove structure enhances the sealing between the stator and rotor assemblies, significantly improving the motor's protection level and extending its service life.

[0007] Preferably, the diameter of the first annular groove is larger than that of the second annular groove, and the first and second annular grooves do not contact each other. The larger diameter of the first annular groove provides a wider sealing space, ensuring good sealing performance even after long-term operation and a certain degree of wear. The non-contact design reduces friction between components, lowers the wear rate, and further enhances the reliability and durability of the motor.

[0008] Preferably, both the first and second annular grooves are located on the outer periphery of the shaft. Positioning the annular grooves on the outer periphery of the shaft makes the protective structure more concentrated and efficient. This layout helps optimize the internal space of the motor, improves the overall structural compactness, and ensures that the shaft can effectively prevent the intrusion of external impurities during rotation, thus enhancing the shaft's stability and reliability.

[0009] Preferably, the shaft is located at the center of the housing and extends outside the housing, with its top end extending into the stator assembly. This shaft design ensures precise alignment and stable rotation of the rotor assembly, reducing vibration and noise. The portion extending outside the housing facilitates connection to external transmission devices, improving the motor's versatility and adaptability, while the top end extending into the stator assembly enhances the interaction between the rotor and stator, improving the motor's operating efficiency.

[0010] Preferably, retaining rings are provided on the outer periphery of the shaft at both the top and bottom ends of the stator assembly, and bearings are provided on the outer periphery of the retaining rings. The shaft is housed in a bearing seat on the inner sidewall of the bottom end of the housing, with a shim between the retaining ring and the bearing seat. The retaining rings effectively limit the axial displacement of the shaft, ensuring its stability during rotation. The bearing installation further reduces friction between the shaft and the stator assembly, improving the smoothness and efficiency of motor operation and extending the service life of the shaft and bearings. Preferably, a steel ring is embedded in the inner sidewall of the housing, and a magnetic ring is provided between the steel ring and the stator assembly. The embedded steel ring enhances the structural strength of the housing, preventing deformation under high-speed rotation and complex operating conditions. The magnetic ring optimizes the magnetic field distribution of the motor, improving its electromagnetic performance and efficiency, while the fit between the steel ring and the magnetic ring also enhances the stability of the rotor assembly.

[0011] Preferably, the stator assembly includes a wound stator, which comprises enameled wire and a plastic-coated iron core. A lead-out sheath is provided at the top of the stator assembly. The combination of enameled wire and plastic-coated iron core improves the electrical insulation performance and mechanical strength of the wound stator. The plastic-coated iron core effectively prevents coil loosening and damage, ensuring the stability and reliability of the winding during long-term operation, while also improving the motor's heat dissipation performance.

[0012] Preferably, the plastic-coated iron core is fixed to the control board using self-tapping screws. The use of self-tapping screws simplifies the installation process and improves production efficiency. This fixing method ensures a tight connection between the plastic-coated iron core and the control board, enhances the overall structural stability of the stator assembly, and facilitates maintenance and replacement.

[0013] Preferably, the plastic-coated iron core and the base are interference-fitted, and a plastic-coated section is provided below the enameled wire. The interference fit ensures a firm connection between the plastic-coated iron core and the base, improving the mechanical strength of the stator assembly. The plastic-coated section further enhances the insulation and protection performance of the winding stator, preventing the enameled wire from getting damp or damaged, and extending the service life of the motor.

[0014] The beneficial effects of this utility model are as follows: This utility model provides a high-protection external rotor DC motor. By setting mutually intersecting first and second annular grooves, the dustproof and waterproof effect is improved, providing a good working environment for internal components and extending service life. Attached Figure Description

[0015] Figure 1 This is an overall structural diagram of the present invention.

[0016] Figure 2 This is a cross-sectional view of the present invention.

[0017] Reference numerals in the attached figures: 1: Stator assembly; 1.1: Electrical control board; 1.2: Enamelled wire; 1.3: Plastic-coated part; 1.4: Plastic-coated iron core; 1.5: Encapsulation part; 1.6: Base; 1.7: First annular groove; 2: Rotor assembly; 2.1: Shaft; 2.2: Housing; 2.3: Steel ring; 2.4: Magnetic ring; 2.5: Bearing; 2.6: Snap ring; 2.7: Dust cover; 2.8: Gasket; 3: Lead wire sheath. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0019] In fields such as industrial automation, smart homes, and new energy equipment, the protective performance of motors directly affects their reliability and service life. Traditional external rotor DC motors often suffer from insufficient dust and water protection design, leading to dust and moisture intrusion, causing winding short circuits, bearing wear, and other malfunctions. This utility model's high-protection external rotor DC motor, through its innovative labyrinthine sealing structure and compact design, provides superior protection for the motor's internal components, significantly improving the motor's operational stability in complex environments.

[0020] like Figure 1 and Figure 2As shown, this high-protection external rotor DC motor mainly consists of a stator assembly 1 and a rotor assembly 2, which achieve a high level of protection through a unique sealing structure. The housing 2.2 of the rotor assembly 2 is rotatably mounted on the outside of the stator assembly 1, forming a typical external rotor structure, which has the advantages of low rotational inertia and large heat dissipation area. The core protection design focuses on the interface between the stator assembly 1 and the rotor assembly 2—the bottom end of the stator assembly 1 has a first annular groove 1.7, and the inner wall of the bottom end of the housing 2.2 of the rotor assembly 2 has a corresponding second annular groove. The two are interlocked to form a multi-layered labyrinth-like sealing barrier. In addition, the stator assembly 1 uses an encapsulation process to fix the electronic control board 1.1, and a dust cover 2.7 is set above the shaft 2.1 to further enhance the dustproof and waterproof effect.

[0021] like Figure 2 As shown, the inner wall of the first annular groove 1.7 is embedded inside the second annular groove, and the outer wall of the second annular groove is embedded inside the first annular groove 1.7, forming a labyrinthine structure resembling interlocking teeth. Taking a certain model of motor as an example, the diameter of the first annular groove 1.7 is designed to be 32mm and the depth to be 2.5mm; the diameter of the second annular groove is 28mm and the depth to be 2.2mm. This nested structure requires airflow or droplets to undergo multiple turns before penetrating the interior, significantly increasing the complexity of the intrusion path. In IP protection level testing, this structure enabled the motor to pass the IP65 test (completely dustproof and water-jet resistant), while motors with traditional single annular groove structures can only achieve an IP54 rating.

[0022] like Figure 2 As shown, the first annular groove 1.7 and the second annular groove do not contact each other, maintaining a radial gap of 0.3-0.5mm. This design has dual advantages: it avoids the wear caused by long-term rotation of traditional contact seals (such as rubber sealing rings). Life tests show that the wear rate of the non-contact structure is reduced by more than 80% compared to the contact type, and the sealing performance shows no significant decline after 1000 hours of continuous motor operation. The larger first annular groove 1.7 (diameter difference of 4mm) provides redundant sealing space, maintaining sealing effectiveness even when the motor's long-term operation causes slight deformation of components, through gap changes.

[0023] like Figure 2 As shown, the optimized axial layout features two annular grooves surrounding the outer periphery of shaft 2.1, forming a concentric protective zone centered on shaft 2.1. This layout ensures the protective structure is symmetrical to the motor's rotation axis, guaranteeing that centrifugal force will not disrupt the uniformity of the sealing gap during high-speed rotor rotation (up to 5000 rpm). Finite element analysis shows that this structure maintains sealing reliability even with rotor vibration displacement ≤0.1 mm, while traditional axial sealing structures may experience leakage due to uneven gaps under the same vibration conditions. Figure 1As shown, shaft 2.1 is located at the center of housing 2.2 and extends outside housing 2.2, with its top end penetrating into stator assembly 1. This design of shaft 2.1 ensures precise alignment and stable rotation of rotor assembly 2, reducing vibration and noise. The portion extending outside housing 2.2 facilitates connection to external transmission devices, improving the motor's versatility and adaptability, while the top end penetrating into stator assembly 1 enhances the interaction between the rotor and stator, improving the motor's operating efficiency.

[0024] like Figure 2 As shown, the encapsulation part 1.5 of the stator assembly 1 completely embeds the control board 1.1 with insulating material, forming an integrated protective housing 2.2. This design is like creating a "safety cabin" for the control board 1.1, preventing moisture in humid environments or accidental oil spills from contacting the precision components on the circuit board. In bathroom fixtures, the control board 1.1 of traditional motors is prone to short circuits due to moisture intrusion. However, the encapsulation process of this motor keeps the control board 1.1 in a dry and sealed state at all times, ensuring circuit stability even during long-term operation in high humidity environments and significantly reducing the probability of equipment failure.

[0025] like Figure 1 As shown, the dust cover 2.7 covers the upper surface of the stator assembly 1 in a dome shape, with a small gap between its inner boss and the top of the shaft 2.1, forming a top dust buffer zone. This design effectively prevents dust accumulation at the shaft shoulder, avoiding the risk of dust entering the motor as the shaft 2.1 rotates. In outdoor fan applications, windy and sandy weather often causes traditional motor shaft systems to make abnormal noises due to dust jamming. However, the dust cover 2.7 design of this motor keeps the shaft system clean at all times, resulting in lower noise and stronger stability during operation.

[0026] like Figure 2 As shown, shaft 2.1 is located at the center of housing 2.2 and is positioned inside stator assembly 1, precisely aligned with stator assembly 1 to ensure the stability of rotor assembly 2 during rotation. This design acts like an "invisible balancer" for the motor, effectively reducing vibration and noise. In smart home fan applications, the noticeable vibration of traditional motors often affects the user experience, while this motor maintains smooth operation even at high speeds, with noise levels controlled within a comfortable range, improving the quietness of use.

[0027] The portion of shaft 2.1 extending out of housing 2.2 facilitates quick connection with transmission devices such as gears and pulleys, adapting to various equipment needs. Whether it's conveyor belt drive in industrial production or joint rotation in home robots, this motor can quickly adapt through its flexible shaft design, demonstrating strong versatility and adaptability.

[0028] The top of shaft 2.1 extends deep into stator assembly 1, shortening the air gap between the rotor and stator, making their electromagnetic interaction more direct and efficient. This design effectively shortens the "distance of power transmission," allowing the motor to respond to control commands more quickly during operation and improving energy conversion efficiency, especially in automated equipment that requires frequent start-stop cycles.

[0029] like Figure 2 As shown, retaining rings 2.6 are provided on both the top and bottom ends of the stator assembly 1 around the outer periphery of shaft 2.1. Bearings 2.5 are mounted on the outer side of retaining rings 2.6, forming a bidirectional axial limiting structure for shaft 2.1. Retaining rings 2.6 are made of spring steel and, through precise heat treatment, can effectively withstand the axial load of rotor assembly 2, preventing shaft 2.1 from shifting during high-speed rotation. For example, at the moment of motor start-up or commutation, retaining rings 2.6 can quickly counteract the axial displacement caused by inertial forces, ensuring a uniform and stable air gap between the rotor and stator, and preventing electromagnetic performance degradation or mechanical wear caused by shaft 2.1 misalignment.

[0030] Bearing 2.5 is preferably a low-noise deep groove ball bearing 2.5, internally filled with long-life lithium-based grease, which maintains stable lubrication performance within a temperature range of -30℃ to 120℃. The installation of bearing 2.5 not only reduces friction between shaft 2.1 and stator assembly 1, but also, through precise tolerance fitting (interference between the inner ring of shaft 2.1 and bearing 2.5 0.005-0.01mm), keeps the radial runout of the motor within a very small range during operation. In practical applications, this design significantly reduces the vibration amplitude of the motor during continuous operation, making it particularly suitable for scenarios with high requirements for noise and stability, such as medical equipment or high-end home appliances.

[0031] Shaft 2.1 is mounted in bearing housing 2.5 on the inner side wall of the bottom end of housing 2.2. Bearing housing 2.5 is made of one-piece aluminum alloy and its inner surface is precision ground to ensure a tight fit with the outer ring of bearing 2.5. A shim 2.8 is placed between the snap ring 2.6 and bearing housing 2.5. Shim 2.8 is preferably made of wear-resistant engineering plastic with a thickness controlled between 0.3-0.5 mm. Its function is to fill the assembly gap and buffer vibration impact. This structural design is like adding a "double stabilizer" to the shaft system: on the one hand, it provides rigid support through bearing housing 2.5, and on the other hand, it absorbs high-frequency vibration through shim 2.8, thereby extending the service life of shaft 2.1 and bearing 2.5 and reducing failures caused by mechanical fatigue.

[0032] like Figure 2As shown, a steel ring 2.3 is embedded in the inner wall of the housing 2.2. The steel ring 2.3 significantly improves the structural strength of the housing 2.2, effectively suppressing radial deformation and preventing rotor-stator friction caused by deformation. For example, in high-load scenarios such as industrial fans, the steel ring 2.3 increases the deformation resistance of the housing 2.2 several times, ensuring that the motor maintains stable mechanical performance under long-term high-load operation.

[0033] A magnetic ring 2.4 is placed between the steel ring 2.3 and the stator assembly 1. The magnetic ring 2.4 forms a uniform magnetic field through a precision magnetization process. The cooperation between the magnetic ring 2.4 and the steel ring 2.3 forms a closed magnetic circuit, effectively reducing leakage magnetic loss and improving the electromagnetic efficiency of the motor. At the same time, the symmetrical arrangement of the magnetic ring 2.4 further enhances the rotational stability of the rotor assembly 2, reduces vibration and noise caused by uneven magnetic field, and significantly improves the smoothness of the motor, especially at low speeds, making it suitable for automated equipment requiring precise control.

[0034] The winding stator consists of enameled wire 1.2 and a plastic-coated iron core 1.4. The enameled wire 1.2 is preferably made of polyurethane enameled wire 1.2 resistant to high-frequency pulses, with the wire diameter precisely matched to the motor power to ensure the winding's current-carrying capacity and heat dissipation performance. The plastic-coated iron core 1.4 is injection molded from laminated silicon steel sheets, with an epoxy resin coating on the outer layer. This design offers multiple advantages: the epoxy resin layer completely isolates the silicon steel sheets from the enameled wire 1.2, avoiding the problem of iron core burrs damaging the enameled wire 1.2 that may occur in traditional winding processes, thus improving the winding's insulation withstand voltage rating; the plastic coating process forms an integral structure between the silicon steel sheets and the enameled wire 1.2, effectively preventing the coil from loosening due to electromagnetic forces during motor start-up or shutdown, making it particularly suitable for industrial scenarios with frequent start-stop operations.

[0035] The stator assembly 1 is equipped with a lead wire sheath 3 at its top. The lead wire sheath 3 is preferably made of high-temperature resistant silicone rubber and has a spiral groove inside to guide the lead wires to be neatly arranged and provide mechanical protection. This design avoids insulation damage to the lead wires caused by vibration and friction, and can significantly reduce the probability of line faults, especially in engineering machinery with large vibrations.

[0036] The plastic-coated iron core 1.4 is fixed to the electrical control board 1.1 with self-tapping screws, ensuring a tight connection without damaging the plastic coating. This fixing method eliminates the need for pre-drilling, simplifying the assembly process and improving the production efficiency of the stator assembly 1. Simultaneously, the detachable design facilitates quick replacement of the iron core or electrical control board 1.1 during later maintenance, reducing maintenance costs.

[0037] The plastic-coated iron core 1.4 and the base 1.6 are fitted with an interference fit, with the interference controlled between 0.02-0.04mm. The iron core is pressed into the positioning hole of the base 1.6 using a press. This connection method requires no additional fasteners to form a robust mechanical connection, making it particularly suitable for the mass production of high-precision motors. The interference fit not only improves the overall rigidity of the stator assembly 1 but also avoids the loosening risk that may occur with traditional threaded connections, exhibiting stronger stability under high-speed rotation or impact loads.

[0038] A plastic-coated section 1.3 is located below the enameled wire 1.2. The plastic-coated section 1.3 further enhances the insulation and protection performance of the winding stator, preventing the enameled wire 1.2 from getting damp or damaged, thus extending the motor's service life. It prevents short circuits caused by wear on the metal edge of the base 1.6, especially after long-term motor operation, as the plastic-coated section 1.3 effectively slows down insulation aging; it absorbs vibration energy between the winding and the base 1.6, reducing the risk of enameled wire 1.2 breakage due to mechanical stress; and, in conjunction with the labyrinth seal structure, further prevents external moisture and dust from entering the winding area from the bottom, extending the motor's service life in humid or highly polluted environments.

[0039] Assembly process.

[0040] This utility model consists of a stator assembly 1 and a rotor assembly 2. The stator assembly 1 mainly consists of a base 1.6, a winding stator, an electrical control board 1.1, and an encapsulation part 1.5. The winding stator consists of enameled wire 1.2 and a plastic-coated iron core 1.4. During production, after the plastic-coated iron core 1.4 is wound, it is fixed to the electrical control board 1.1 with self-tapping screws. Then, the plastic-coated iron core 1.4 is fixed to the base 1.6 with an interference fit. Finally, the entire assembly is encapsulated using a mold, with the electrical control board 1.1 inside the encapsulation part 1.5. The rotor assembly 2 consists of a shaft 2.1, a steel ring 2.3, a magnetic ring 2.4, and a housing 2.2. During production, the shaft 2.1 and the steel ring 2.3 are placed in a mold, and the housing 2.2 is formed by injection molding. Then, the magnetic ring 2.4 is inserted. After the stator and rotor are assembled, the dust cover 2.7 is pressed in. The first annular groove 1.7 and the second annular groove between the stator and rotor form a labyrinthine waterproof structure, which can effectively improve dust and water resistance, provide a good working environment for the bearing 2.5, and effectively extend the service life of the bearing 2.5.

[0041] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this utility model.

Claims

1. A high-protection external rotor DC motor, characterized in that, It includes a stator assembly and a rotor assembly. The housing of the rotor assembly is rotatably disposed outside the stator assembly. The bottom end of the stator assembly is provided with a first annular groove, and the inner wall of the bottom end of the housing is provided with a second annular groove. The first annular groove and the second annular groove are arranged to intersect each other. The stator assembly includes an encapsulation section, an electronic control board is embedded in the encapsulation section, and a dust cover is provided on the upper surface of the stator assembly above the shaft of the rotor assembly.

2. The high-protection external rotor DC motor according to claim 1, characterized in that, The inner wall of the first annular groove is disposed within the second annular groove, and the outer wall of the second annular groove is disposed within the first annular groove.

3. A high-protection external rotor DC motor according to claim 2, characterized in that, The diameter of the first annular groove is larger than that of the second annular groove, and the first and second annular grooves do not contact each other.

4. A high-protection external rotor DC motor according to claim 1, 2, or 3, characterized in that, Both the first and second annular grooves are located on the outer periphery of the shaft.

5. A high-protection external rotor DC motor according to claim 4, characterized in that, The shaft is located at the center of the housing and extends outside the housing, with its top end penetrating into the stator assembly.

6. A high-protection external rotor DC motor according to claim 1 or 5, characterized in that, The outer periphery of the shaft is provided with retaining rings at the top and bottom of the stator assembly, and bearings are provided on the outer periphery of the retaining rings.

7. A high-protection external rotor DC motor according to claim 1 or 5, characterized in that, A steel ring is embedded in the inner wall of the housing, and a magnetic ring is provided between the steel ring and the stator assembly.

8. A high-protection external rotor DC motor according to claim 1, characterized in that, The stator assembly includes a winding stator, which includes enameled wire and a plastic-coated iron core.

9. A high-protection external rotor DC motor according to claim 8, characterized in that, The plastic-coated iron core is fixed to the control board with self-tapping screws.

10. A high-protection external rotor DC motor according to claim 9, characterized in that, The plastic-coated iron core and the base are interference-fitted, and the plastic-coated part is located below the enameled wire.

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