Motor bearing selection effect on the reliability of brushless dc motor using the low temperature environment condition, bearing radial clearance design flow will lead to motor is sound. Low temperature state of bearing outer ring contraction, resulting in smaller radial clearance, and bearing radial clearance down when manufacturing tolerances, brushless dc motor will cause friction ball and raceway running hard, and in sound condition. Bearing assembly bearing inner ring when squeezed, can also lead to smaller radial clearance.
to investigate analysis:
1, examine whether the motor bearing assembly process anomalies, including the motor shaft bearing size and shaft end R Angle;
2, bearing radial clearance adjustment. Bearing radial clearance (Such as tolerance by 5 -U is adjusted for 8 to 1215u）, replace the bearing on early abnormal feedback motor, electric operation on low temperature check again whether the same sound, the scheme. If a radial clearance adjustment is too large, bearing running easily beat big problems (Especially in high temperature environment), bearing radial clearance of synchronization need to increase the bearing assembly preloading, the rectification of the motor design plan to do some adjustment; Bearing radial clearance is small, the simulation makes the ball and raceway rigid friction condition, on the initial feedback abnormal motor, electric operation on normal temperature checking whether there will be a similar sound during the low temperature operation scheme for demonstration.
3, bearing oil physical properties of variance analysis. Sound of motor bearing grease increase general base oil viscosity at low temperature, high oil viscosity influence centrifugal separation and migration flows. This grease is easy to appear in long-distance transportation packaging antivibration ja abrasion, further lead to the emergence of the sound at low temperature.
countermeasures:
1, strengthen the dimensional tolerance control manufacturing process;
2, adjust the bearing radial clearance, avoid assembly preloading;
3, adjust the bearing oil viscosity, to adapt to the physical properties of the low temperature state changes.
