Fig 1.
The total number of papers on tolerance design and optimization in the previous fifteen years (Web of Science, accessed on 20th October 2025).
Fig 2.
Error surface and tolerance area.
Fig 3.
Gear mechanism.
Fig 4.
Assembly relationship diagram.
Table 1.
Temperature of stator winding, casing and cap.
Fig 5.
Temperature rise test platform of motor system.
Fig 6.
Grid division results of motor.
Table 2.
Volume and heat generation rate of each motor component.
Table 3.
Calculation results of each convective heat transfer coefficient.
Fig 7.
Boundary condition setting and loading result diagram of the test motor.
Fig 8.
Total thermal deformation cloud diagram of the motor under steady-state operating conditions.
Table 4.
The deformation of each part of the motor.
Fig 9.
Motor assembly drawing.
Fig 10.
1.1 Inner surface of stator 1.2 Outer surface of stator 2.1 Inner surface of casing 2.2 Left end surface of casing 2.3 Left stop cylindrical surface of casing 2.4 Right end surface of casing 2.5 Right stop cylindrical surface of casing 3.1 End surface of front end cover 3.2 Stop cylindrical surface of front end cover 3.3 Surface of front end cover bearing compartment 4.1 End surface of rear end cover 4.2 Rear stop cylindrical surface of rear end cover 4.3 Surface of rear end cover bearing compartment 5.1 Outer surface of left bearing 5.2 Inner surface of left bearing 6.1 Outer surface of right bearing 6.2 Inner surface of right bearing 7.1 Mating surface of rotor shaft and right bearing 7.2 Mating surface of rotor shaft and left bearing 7.3 Mating surface of rotor shaft and rotor 8.1 Inner surface of rotor 8.2 Outer surface of rotor.
Fig 11.
Error transfer path of air gap between features 8.2 and 1.1 in the motor assembly.
(a) path Ⅰ (b) path Ⅱ.
Table 5.
Tolerance information after considering thermal deformation.
Fig 12.
Functional requirement polyhedron of motor assembly considering thermal deformation.
Fig 13.
Ideal functional requirement polyhedron of the motor assembly without considering thermal deformation.
Table 6.
MOPSO algorithm control parameter setting.
Fig 14.
Machining cost and quality loss cost optimization Pareto frontier of machining cost and quality loss cost in motor tolerance optimization.
Table 7.
Tolerance optimization result.
Fig 15.
Optimized polyhedron of motor assembly error.
Table 8.
Assembly error value.
Fig 16.
Optimization before and after cost comparison.
Table 9.
Motor core tolerance-cost sensitivity analysis results.