In the motor design, the design of the bearing chamber is too important
For the bearing system problem of the motor product, it is obviously unscientific to talk about the bearing separately, especially for the design, processing, installation and later use of the bearing chamber.
Selection and requirements for bearing chamber design
●The bearing casing and the bearing indoor diameter should not have interference, but the clearance can not be large. For the basic series of motors, the standards adopted by many motor manufacturers and the tolerances of the indoor diameters recommended in this paper are shown in the table below.
After the bearing is heated, the working clearance is reduced before use. The degree of reduction is different under different temperature conditions, and different materials will also correspond to different reductions.
In order to prevent the bearing outer ring from rotating in the bearing chamber (ie running circle), the accumulated axial clearance of the bearing chamber parts should be moved from the outer ring of the bearing to the end cover or bearing sleeve, that is, the outer ring of the bearing should be inside the bearing, The cover is stuck. For an explosion-proof motor, the clearance should be less than 0.2 mm.
● The bearing chamber should be as far as possible from the stator and rotor windings, and the ventilation and heat dissipation should be good. For motors with internal circulation ventilation, if one end of the bearing is at a high temperature, the cooled air should be blown as much as possible. In order to dissipate heat, when using grease-lubricated bearings, two bearings should not be used at the same end.
● Lubrication-bearing parts related to lubrication should be designed to contain a sufficient amount of grease and to drain excess grease. For example, the "oil pan" with a bevel can pull the waste grease from the bearing out of the bearing chamber into the oil storage chamber of the outer cover. For high-speed, high-power motors, thin oil lubrication can be used to solve the bearing heating.
● Easy to disassemble. When designing the motor-related components, it is necessary to try to introduce the bearing into the bearing chamber at the time of assembly, and then insert the rear end cover into the seat of the human seat to avoid damage to the bearing during assembly; when disassembling, the bearing inner cover should be placed. The space for the removal tool.
● Add temperature monitoring device, but the alarm temperature should be selected according to the buried position of the temperature measuring component. Do not approach the maximum allowable temperature of the bearing regardless of the position buried in the bearing, such as 95 °C for ordinary bearings.
Other countermeasures to reduce bearing system problems
●The bearing distance should not be too large. Over the assembly, the bearing damage will be accelerated due to the increased deflection of the shaft.
● The motor center height should be as low as possible. First, the center of gravity is low and stable; second, after installation and operation, the center height change due to thermal expansion is small. The motor with a center height greater than 400 is installed and debugged at normal temperature. After the load is running, the center height should be raised by 0.1-0.3mm. If the dragged device cannot be raised, or the lift is less than this value, the bearing It is necessary to withstand additional forces, which will inevitably lead to accelerated damage.
● The rigidity of the motor itself should be good, and no resonance should be generated or approached during operation.
● Sealing the bearing parts is better. The degree of protection at the inner and outer covers of the motor bearing should meet the requirements of the actual use environment.
● For larger motors, measures should be taken to prevent shaft currents from accelerating bearing damage due to electrical corrosion.
