Key considerations in the design of series motors
The design of series motors, especially the design of basic series motors, is a work that has a significant impact on the market. Therefore, before designing, it is necessary to conduct sufficient investigation, research, analysis and comparison of the existing series or similar motors at home and abroad, work according to the above requirements, and provide practical basis for comprehensive design through trial production of a few typical specifications. Ms., today I will talk to you about the issues that must be paid attention to in the design process of series motors. A good design can achieve multiple specifications of products with minimal components.
1 Power level
The ratio of adjacent power levels in the same series (high power to low power) is called the power increase coefficient or capacity increase coefficient K, which directly affects the determination of the number of power levels in the entire series and has a significant impact on the economics of the series.
If K is small, there will be more power levels, which is easy to meet the matching needs of different users, convenient to choose, and can reduce over installation capacity, over installation costs, and operating costs. However, the increase in power levels will result in a wider range of motor specifications within the same series, requiring more manufacturing equipment and complex production management, thereby increasing manufacturing costs. There are specific provisions in national standards regarding priority coefficients for this issue.
Using a priority number system can achieve reasonable segmentation and meet the driving needs of various devices with the minimum number of specifications and varieties. At this point, the ratio between the installed capacity of each level and the power of the motor itself is roughly equal, making it more reasonable. Considering that the actual demand for motors of different specifications in the same series is not the same, motors with lower power generally require more, while motors with higher power require relatively less, and some individual types of power may require particularly more or less. Therefore, if the entire series adopts the same power increasing coefficient, that is, only using a basic priority number system with the same common ratio, it may not be suitable. Therefore, the standard stipulates that when necessary, it is allowed to use a composite priority number system, which means using different priority number systems within different power ranges, so that the spacing is sparse in the low power range and dense in the high power range. Individual power segments can also be sparse or dense compared to adjacent segments according to specific circumstances.
Determination of installation dimensions and correspondence between power level and installation dimensions
The installation dimensions of the motor refer to the relevant dimensions when the motor is installed with the supporting machinery. It is very important to determine the installation size and power level of a series of motors in a reasonable manner, and the corresponding relationship with the installation size. The installation dimensions of series motors are generally classified according to the height of the shaft center, and their determination must take into account the specific conditions of the supporting machinery and the motor itself. In principle, they should also be increased according to the priority number system.
In terms of installation dimensions, the main focus is on the height of the shaft center. For motors with end cap bearings, the correspondence between power level and installation dimensions is mainly determined by the correspondence between power level and shaft center height. After determining the power level, if the number of high-level shaft centers selected is too small, although the process equipment for motor manufacturing can be reduced and user installation and use can be more convenient, the electromagnetic design will not be reasonable enough and materials will not be fully utilized. Therefore, when determining this correspondence, comprehensive consideration must be given, and multiple schemes must be calculated and compared. Usually, one axis center height corresponds to two power levels; Within certain power ranges, it can also correspond to three power levels.
Determination of outer diameter of stator laminations for AC series motors
When determining the outer diameter of stator laminations for AC series motors, attention should be paid to the following main factors: 1) consistency with the specified shaft center height value. Practice has proven that when the axis center is raised, if possible, it is advisable to appropriately enlarge the outer diameter of the stator laminations, which is beneficial for both the performance and processability of the motor. 2) The economic rationality of utilizing silicon steel sheets. 3) The symmetry of the entire series' appearance; And, if conditions permit, make full use of existing process equipment.
Standardization, serialization, and universalization of 4 components
Series motor components should adopt standard parts, sizes, and structures as much as possible, and arrange the sizes of similar components reasonably according to the requirements of the entire series to improve universality and interchangeability. For example; For AC motors, 2-3 specifications with the same number of poles and adjacent power levels should use the same stator laminations (with different iron core lengths). For motors with different numbers of poles and adjacent power levels, it is recommended to use the same stator laminations with the same outer diameter but different inner diameters, and the same or slightly different iron core lengths. For DC motors with different speeds but adjacent powers, the same armature outer diameter and magnetic pole punch should be selected. In this way, the number of stamping dies and special molds will be greatly reduced, and the number of process equipment such as fixtures and measuring tools will be further reduced because the same shaft diameter, bearings, commutators, and winding brackets can be used.
In order to make the main dimensions of the motor more suitable, for large batches of motors, the outer diameter of one iron core is generally limited to two types of iron core lengths, and some are limited to three types; For motors with smaller batches, generally two or more lengths can be used, especially for high-power motors. When welding the machine base, the change in length will not cause significant inconvenience in the process, so the iron core sometimes uses 3-4 or more lengths.
5 possibilities of derivation
That is to say, it is possible to derive certain products with only minor modifications to meet the requirements of special performance, special environment, and special usage conditions.
