Modelling of assembly error and tolerance optimization for motor based on polyhedral model and thermal deformation analysis

The air gap between the stator and rotor of an electric motor is a crucial parameter that influences its performance. A well-designed tolerance can effectively control the size of the air gap, which results from the accumulation of machining deviations. Using the air gap as an assembly functional requirement, a polyhedral model was developed to represent the assembly deviation transfer path. The effects of thermal loads under actual operating conditions were considered, and thermal deformation was incorporated into the deviation transfer path analysis. By applying Minkowski summation and intersection operations, the cumulative errors of the assembly polyhedron were determined, and the impact of thermal deformation on the assembly errors in the motor was analyzed. A multi-objective tolerance optimization model was developed, with processing and quality loss costs as the objective functions. Considering thermal deformation, a multi-objective particle swarm optimization algorithm was employed to optimize the tolerances of the motor’s critical components, providing a novel theoretical method and technical reference for assembly error analysis and tolerance optimization in electric motors.