Long-service-life high-voltage direct current motor capable of improving EMI

Abstract

The utility model discloses an EMI-improved long-life high-voltage direct current motor, which is characterized by comprising a motor body, an end cover is arranged at the tail end of the motor body, carbon brushes extending out of the end cover are respectively arranged in two opposite sides of the end cover, brush holder assemblies are arranged on the outer sides of the carbon brushes, and the brush holder assemblies are arranged on the outer sides of the carbon brushes. An insulating cover is further arranged on the outer side of one end, exposed out of the end cover, of the brush holder assembly, and an electromagnetic shielding cover is arranged on the outer side of the insulating cover, by means of the method, electromagnetic waves generated in the working process of the motor are effectively prevented from interfering with other electronic devices through the arrangement of the electromagnetic shielding cover, the EMI suppression effect of the motor is remarkably improved, and the service life of the motor is prolonged. And through the electrical connection of the insulating cover, the electromagnetic shielding cover and the brush holder assembly, the use safety is ensured, meanwhile, the heat dissipation performance is improved through the heat dissipation fins, and the service life of the motor is prolonged.

Description

Technical Field

[0001] This utility model relates to the field of DC motor technology, and in particular to a long-life high-voltage DC motor with improved EMI. Background Technology

[0002] Floor brush motors generally operate on 110V to 240V AC power. They typically use a rectifier to convert AC power into DC power as the motor's power source. These motors generally have poor heat dissipation, high power, and high temperature rise. As the motors operate at high temperatures for extended periods, their lifespan is significantly shortened. However, customers not only demand increasingly longer product lifespans but also require compliance with electromagnetic compatibility (EMC) requirements. How to improve motor lifespan while meeting EMI requirements is a significant challenge in motor design.

[0003] The existing solutions are to use brush-braided carbon brushes to meet high power requirements, design longer carbon brushes to improve motor life, and add multi-stage filtering circuits inside and outside the motor to improve EMI. However, the extended carbon brushes extend out of the housing along with the brush holders, and the interference signals generated by the motor are more likely to radiate electromagnetic waves outward through the exposed metal brush holders, which makes it very difficult to improve the EMI of the motor.

[0004] Therefore, there is an urgent need to design a long-life high-voltage DC motor with improved EMI to solve one or more technical problems that are lacking in the existing technology. Summary of the Invention

[0005] The technical solution adopted by this utility model to solve the above-mentioned technical problems is: a long-life high-voltage DC motor with improved EMI, characterized in that it includes: a motor body, an end cover at the tail end of the motor body, carbon brushes extending out of the end cover on opposite sides of the end cover, a brush holder assembly on the outer side of the carbon brush, an insulating cover on the outer side of the end of the brush holder assembly that protrudes outside the end cover, and an electromagnetic shielding cover on the outer side of the insulating cover.

[0006] In a preferred embodiment, an electromagnetic absorption and heat-conducting layer is deposited on the inner side of the electromagnetic shield.

[0007] In a preferred embodiment, the electromagnetic absorption thermal conductive layer has a gradient layer structure with a thickness of 50-200 μm.

[0008] In a preferred embodiment, the outer side of the electromagnetic shield is provided with heat dissipation fins.

[0009] In a preferred embodiment, the height of the heat dissipation fins is gradually distributed.

[0010] In a preferred embodiment, the surface array of the heat dissipation fins is provided with microgrooves.

[0011] The beneficial effects of this utility model are: by setting up an electromagnetic shield, the electromagnetic waves generated during the operation of the motor are effectively blocked from interfering with other electronic devices, and the EMI suppression effect of the motor is significantly improved. In addition, by using an insulating cover, the electrical connection between the electromagnetic shield and the brush holder assembly is blocked, ensuring safety in use. At the same time, the heat dissipation performance is improved by using heat sink fins, extending the service life of the motor. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of this utility model;

[0013] Figure 2 This is a schematic diagram of the end cap structure of this utility model;

[0014] Figure 3 This is a schematic diagram of the electromagnetic shielding cover of this utility model.

[0015] In the picture:

[0016] 10. Motor body; 11. End cap; 12. Brush holder assembly; 13. Insulating cover; 14. Electromagnetic shielding cover; 15. Electromagnetic absorption and heat conduction layer; 16. Heat dissipation fins; 17. Microgrooves. Detailed Implementation

[0017] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0018] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection" and "installation" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Furthermore, "connection" can be a direct connection or an indirect connection through an intermediate medium. "Fixed" means that the relative positional relationship remains unchanged after the connection. The directional terms mentioned in the embodiments of this utility model, such as "inner," "outer," "top," and "bottom," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this utility model, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this utility model.

[0019] In this embodiment of the invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0020] In this embodiment of the utility model, "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0021] References to "one embodiment" or "some embodiments" as used in this specification mean that one or more embodiments of the present invention include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] like Figures 1-2 As shown, this utility model provides a long-life high-voltage DC motor with improved EMI, characterized in that it includes: a motor body 10, an end cover 11 at the tail end of the motor body 10, carbon brushes extending out of the end cover 11 on opposite sides of the end cover 11, a brush holder assembly 12 on the outer side of the carbon brushes, an insulating cover 13 on the outer side of the end of the brush holder assembly 12 that protrudes outside the end cover 11, and an electromagnetic shielding cover 14 on the outer side of the insulating cover 13.

[0023] In a preferred embodiment, an electromagnetic absorption and heat-conducting layer 15 is deposited on the inner side of the electromagnetic shield 14.

[0024] In a preferred embodiment, the electromagnetic absorption and thermal conductive layer 15 has a gradient layer structure with a thickness of 50-200 μm.

[0025] In a preferred embodiment, heat dissipation fins 16 are provided on the outer side of the electromagnetic shielding cover 14.

[0026] In a preferred embodiment, the height of the heat dissipation fins 16 is gradually distributed.

[0027] In a preferred embodiment, the surface array of the heat dissipation fins 16 is provided with microgrooves 17.

[0028] Specifically, the motor body 10 is a traditional carbon brush motor. An end cover 11 is provided at one end of the motor body 10 away from the output end. Carbon brushes are respectively provided on the two sides opposite to the end cover 11. The carbon brushes extend out of the end cover 11, and a metal brush holder assembly 12 is fitted on the outside of the carbon brushes. The brush holder assembly 12 adopts existing conventional technology, so it will not be described in detail here. In order to prevent the electromagnetic waves of the motor from radiating outward through the carbon brushes, an electromagnetic shielding cover 14 is fitted on the outside of the brush holder assembly 12. The electromagnetic shielding cover 14 blocks the radiation of electromagnetic waves to avoid interference with other nearby electronic devices. At the same time, since the electromagnetic shielding cover 14 is usually made of metal and the gap between it and the brush holder assembly 12 is small, in order to prevent current flow between the two and thus safety risks, an insulating cover 13 is also fitted on the end of the brush holder assembly 12 that is exposed outside the end cover 11. The insulating cover 13 blocks the current flow between the electromagnetic shielding cover 14 and the brush holder assembly 12, ensuring the safety of use.

[0029] In another embodiment, such as Figure 3 As shown, to further enhance the effect of the electromagnetic shielding cover 14, an electromagnetic absorption and thermal conductivity layer 15 is deposited on the inner side of the electromagnetic shielding cover 14 using a magnetron sputtering process. This electromagnetic absorption and thermal conductivity layer 15 is made of nano-zinc oxide (ZnO) and has a gradient layer structure, i.e., the surface layer is enriched with nanowire arrays, and the bottom layer is a dense layer. The thickness of the electromagnetic absorption and thermal conductivity layer 15 is preferably 50-200μm, which can be determined according to actual application requirements. The nanowire array forms a three-dimensional conductive network, which attenuates high-frequency electromagnetic waves (>100MHz) through multiple reflection-absorption mechanisms. The dense layer suppresses low-frequency magnetic field interference (<10MHz) through eddy current effects. At the same time, the phonon conduction path of the ZnO nanowire array is optimized, which increases the thermal conductivity to 15W / (m·K) (3 times higher than that of ordinary metal plating). In actual testing, this structure can reduce the surface field strength of the shielding cover by 8dBμA / m at a frequency of 1GHz compared with the traditional nickel plating process, while reducing the hot spot temperature by 12℃.

[0030] To further enhance heat dissipation, heat dissipation fins 16 are also provided on the outside of the electromagnetic shielding cover 14. These fins are designed to match the main electromagnetic interference frequency band generated during motor operation. Adjacent heat dissipation fins 16 are spaced at specific intervals. Taking 500MHz as an example, the calculation formula is based on the λ / 4 wavelength resonance principle:

[0031]

[0032] λ : free space wavelength; Speed ​​of light (3×10) 8m / s); Target suppression frequency (e.g., 500MHz); The relative permittivity of the plastic shell material (e.g., ε_r = 3.2 for ABS plastic).

[0033] Example calculation:

[0034] For the 500MHz interference frequency:

[0035]

[0036] In actual design, the value needs to be rounded to fit the manufacturing process (e.g., 80mm).

[0037] At the same time, in order to expand the effective suppression bandwidth and avoid the limitations of single-frequency resonance;

[0038] The height of the heat dissipation fins 16 is distributed according to an exponentially varying law (5mm→15mm), corresponding to a resonant frequency range of 200MHz-1GHz.

[0039] The height difference Δh between adjacent fins satisfies:

[0040]

[0041] in, .

[0042] like Figure 3 As shown (for ease of understanding) Figure 3 Taking one of the heat dissipation fins 16 as an example (with micro-grooves 17), in order to reduce the resistance of the heat dissipation fins 16 to airflow, several micro-grooves 17 are arranged in an array on the surface of each heat dissipation fin 16. The depth of the micro-grooves 17 is 0.1 mm and the spacing is 0.5 mm. The biomimetic shark skin texture is used to reduce airflow resistance, and the drag coefficient is reduced by 18%.

[0043] The trench depth (0.1 mm) is approximately equal to the skin depth of the target frequency band (the skin depth of copper at 500 MHz is approximately 0.003 mm), forming a surface wave trap. The trench forms a longitudinal eddy current generator, which disrupts the boundary layer and increases the convective heat transfer coefficient by 40%. The spacing (0.5 mm) is approximately equal to λ / 60 (corresponding to a 1 GHz wavelength), generating localized surface plasmon resonance.

[0044] The wavelength matching design enables the heat dissipation fins 16 to form an electromagnetic wave resonant cavity, converting radiation energy in a specific frequency band into heat energy (measured to provide an additional 6dB improvement in radiation suppression in the 200-500MHz frequency band); the micro-groove structure 17 improves the air convection heat transfer coefficient by 40% through the turbulence enhancement effect (heat dissipation power reaches 25W / m²·K at a wind speed of 2m / s).

[0045] In summary, the electromagnetic shielding cover 14 effectively blocks the electromagnetic waves generated during motor operation from interfering with other electronic devices, significantly improving the EMI suppression effect of the motor. Furthermore, the insulating cover 13 isolates the electrical connection between the electromagnetic shielding cover 14 and the brush holder assembly 12, ensuring safety during use. At the same time, the heat dissipation fins 16 improve heat dissipation performance and extend the service life of the motor.

[0046] This invention is not limited to the description in the specification and embodiments. Therefore, other advantages and modifications can be readily realized by those skilled in the art. Thus, without departing from the spirit and scope of the general concept as defined by the claims and their equivalents, this invention is not limited to the specific details, representative devices and illustrated examples shown and described herein.

Claims

1. A long-life high-voltage DC motor with improved EMI, characterized in that, include: The motor body has an end cap at its tail end. Carbon brushes extending out of the end cap are respectively provided on the two opposite sides of the end cap. A brush holder assembly is provided on the outside of the carbon brush. An insulating cover is provided on the outside of the end of the brush holder assembly that is exposed outside the end cap. An electromagnetic shielding cover is provided on the outside of the insulating cover.

2. The long-life high-voltage DC motor with improved EMI according to claim 1, characterized in that, An electromagnetic absorption and heat-conducting layer is deposited on the inner side of the electromagnetic shield.

3. The long-life high-voltage DC motor with improved EMI according to claim 2, characterized in that, The electromagnetic absorption and heat-conducting layer has a gradient layer structure with a thickness of 50-200 μm.

4. The long-life high-voltage DC motor with improved EMI according to claim 1 or 2, characterized in that, The electromagnetic shielding cover is equipped with heat dissipation fins on its outer side.

5. The long-life high-voltage DC motor with improved EMI according to claim 4, characterized in that, The height of the heat dissipation fins is gradually distributed.

6. The long-life high-voltage DC motor with improved EMI according to claim 4, characterized in that, The surface array of the heat dissipation fins is provided with microgrooves.

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