Key issues to be considered when designing a series of motors

Key issues to be considered when designing a series of motors

The design of the series of motors, especially the design of the basic series of motors, is a work that has a major impact on the market. Therefore, before design, it is necessary to fully investigate and analyze the existing series or similar motors at home and abroad, and work according to the above requirements, and provide practical basis for the comprehensive design by trial production of a few typical specifications. Ms. Join me today to talk about the issues that must be paid attention to during the design of the series motor. A good design allows for multiple sizes of products with the fewest parts.

1 power level

The ratio of two adjacent power levels in the same series (high power ratio and low power) is called the power increment coefficient or the capacity increment coefficient K, and its value directly affects the determination of the number of power levels of the entire series, and has economics for the series. Significant influence.

K is small and has many power levels. It is easy to meet the needs of different users. It is easy to select and can reduce installation capacity, installation cost and operation cost. However, the increase in the power level will result in more specifications for the motors in the same series, increased process equipment required for manufacturing, and complicated production management, thereby increasing manufacturing costs. In response to this problem, there are specific provisions on priority factors in national standards.

The priority number system can be used to achieve reasonable segmentation, and meet the driving needs of various devices with the minimum specifications. At this time, the ratio between the installed capacity of each stage and the power of the motor itself is approximately equal, which is more reasonable. Considering that the actual requirements of motors of different specifications in the same series are not the same, motors with low power generally require more, and motors with larger powers require relatively less, and individual powers may need to be particularly large or extremely small. . Therefore, if the entire series adopts the same power increment coefficient, that is, it is not necessarily suitable to use only one basic priority number of the same common ratio. To this end, the standard stipulates that the composite priority number system is allowed when necessary, that is, different priority numbers are used in different power ranges, so that the interval in the small power range is sparse, the interval in the high power range is dense, and the individual power segments can also be used. According to the specific situation, it is thinner or denser than the adjacent segments.

2 Determination of installation dimensions and correspondence between power levels and installation dimensions

The mounting dimensions of the motor refer to the dimensions of the motor and the associated machine when it is installed. How to reasonably determine the installation dimensions of the series motor and the correspondence between the power level and the installation size is very important. The installation dimensions of series motors are generally graded according to the height of the shaft center. It must be determined comprehensively considering the specific conditions of the supporting machinery and the motor itself. In principle, it should also be incremented according to the priority number.

The installation dimension is mainly the shaft center height, and the motor corresponding to the end cap type bearing is mainly to determine the corresponding relationship between the power level and the shaft center height when determining the correspondence between the power level and the installation size. After the power level is determined, if the number of high-level axes of the selected shaft is too small, the process equipment of the motor can be reduced, and the user is more convenient to install and use, but the electromagnetic design will not be reasonable enough, and the materials are not fully utilized. Therefore, this correspondence must be fully considered and the calculation and comparison of various schemes should be carried out. Usually one axis center height corresponds to two power levels; in the individual power range, three power levels are also available.

3 Determination of the outer diameter of stator windings of AC series motors

When determining the outer diameter of the AC series stator blades, the following main factors should be noted: 1) Consistency with the specified shaft center height values. Practice has proved that when the height of the shaft center is high, if possible, it is appropriate to properly enlarge the outer diameter of the stator punch, which is advantageous for the performance and processability of the motor. 2) Economic rationality of the utilization of silicon steel sheets. 3) The symmetry of the entire series of shapes; and, if conditions permit, can make full use of existing process equipment.

4 standardization, serialization and generalization of parts

Series motor parts should adopt standard parts and standard size and standard structure as much as possible, and arrange the size of the same type of parts according to the requirements of the whole series to improve versatility and interchangeability. For example, for an AC motor, the number of poles is the same, and the power level is adjacent to 2~3 specifications. The same stator punching chip should be used (the core length is different at this time). For motors with different pole numbers and power levels, the same stator should be used. The outer diameter of the punch, but the inner diameter is different, and the core length is the same or slightly different. For DC motors with different speeds and adjacent power, the same armature outer diameter and pole punch should be used. In this way, the number of dies and special dies can be greatly reduced, and the number of process equipment such as jigs and gauges can be further reduced by using the same shaft diameter, bearing, commutator and winding bracket.

In order to make the main size ratio of the motor more suitable, for large-volume motors, the outer diameter of one core is generally limited to two kinds of core lengths, and the other is three kinds; for motors with smaller batches, generally more than two kinds of lengths, especially power. Large motors, when using a welded base, do not cause large inconveniences in the process, so the core sometimes uses 3 to 4 lengths or more.

5 possibility of derivation

That is, it should be considered that it is possible to derive certain products with only minor modifications to meet the requirements of special performance, special environment and special use conditions.