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Guangdong Chaoli Motor Co.,Ltd.

Research and development project case of ultra-high speed and long life split brush DC motor for electric tools

Development basis and background

With the development of social economy, in recent years, battery-type electric tools and small household robots and other products can be described as rapid development, its proportion in practical applications is also increasing year by year, such products generally require high precision micro-motor control, complex working environment, compact structure, so the micro-motor put forward higher technical requirements. Includes:

1) The torque-to-inertia ratio is large, and the electromechanical time constant is small to meet the requirements of rapid response of the system;

2) The speed range is wide, the speed runs smoothly, and the torque fluctuation should be small to meet the requirements of various motion speeds and precise positioning;

3) The power-to-volume ratio and the power-to-weight ratio are large to meet the limited installation space, that is, the micro-motor is required to be miniaturized and lightweight as much as possible;

4) requires large overload capacity, good heat resistance, in harsh environmental conditions, can work for a long time, that is, has good environmental resistance and high reliability.

On the other hand, the efficiency of the traditional permanent magnet DC brush micro motor is generally about 35 ~ 55%. In the case of high torque and high speed, it is more and more difficult to meet the demand in terms of power volume ratio and operation stability. In recent years, the company has gradually tilted to such products in the process of industrial transformation and upgrading. Therefore, the development of high-efficiency high-torque iron core micromotors has its practical and economic significance, which can enrich the company's product types, further increase the company's market share, and enable our motor products to be innovated and upgraded.

Main R & D contents and results

R & D content:

1. Unique split casing and front and rear end cover structure and assembly process design and research-the casing is designed into a left and right discrete assembly structure, and the front and rear end covers are mechanically held by set screws, so as to effectively improve the heat dissipation performance and structural manufacturability of the motor;

2. Performance and structure optimization design of iron core micro motor based on high efficiency and high torque requirements:

1) From the point of view of the system, the slenderness ratio of the motor rotor is reasonably designed, thereby reducing the total cross-section of the wire, so that the working magnetic flux of the motor is correspondingly increased, which meets the requirements of compact motor size and small working current;

2) The introduction of the third-generation rare earth NdFeB permanent magnet material as the stator, which has the characteristics of small size, light weight and strong magnetism, which significantly reduces the weight of the motor, reduces the size of the motor, and obtains high-efficiency effects and Improve the performance of the motor;

3) Research and design the self-adjusting brush installation structure of the rear cover, and select the most suitable spring pressure through experimental comparison to reduce the spark of the motor and the wear of the brush.

3. Tolerance design and modeling analysis of key mating parts

Starting from the balance of cost and quality, design the most reasonable tolerance fit and requirements of shaft and bearing, commutator and brush, iron core and stator, and the parts themselves, take the minimum tolerance cost as the goal of tolerance optimization of the key components of the micro motor, and take the performance requirements and machining economic accuracy of the micro motor as the constraints of tolerance optimization to optimize the tolerance design of the key components of the micro motor, the optimized results were compared and analyzed. Finally, the interchangeability and standardization of parts are realized, and the economic benefits are maximized.

R & D Results:

1. At least 2 new models have been developed. Through the control of motor mechanical characteristics, at least 20 kinds of high-efficiency and high-torque iron core micro-motor derivatives have been extended to fully meet the driving performance and use requirements of battery-type electric tools and small household machines. Make the technical capability of the company's iron core micro-motors to a new level.

2. The efficiency of the motor can reach 68 ~ 75%, and the performance meets the characteristics, design intent and application requirements of the high-efficiency, high-speed, high-torque DC core micro-motor.