About motor bearing selection and bearing system
The air gap of the motor is very small and the uniformity is high. Rolling bearings should be used. The radial clearance of the rolling bearing is small, the friction loss is low, the axial dimension is short, and the lubrication maintenance is simple; the disadvantage is that the noise is large during operation and the performance against the impact load is poor. For motors of H315 and above, ball bearings are used for non-shaft extensions. In addition to bearing radial loads, they can also withstand certain axial loads, which can keep the rotor in the expected axial position and can play an axial position. The shaft end is generally cylindrical bearing to withstand large radial load; for small size motors, and all 2P medium and small motors, ball bearings are used at both ends, but only one of the bearings can be used for axial positioning.
Rolling bearings must have a protective device that stores grease and prevents dust from penetrating.
The small size motor adopts sealed bearing. There are many cases. It is characterized in that there is no inner bearing cover and the oil retaining ring is hot on the shaft, which is easy to assemble. The bearing outer cover and the end cover are integrated, and the outer cover and the outer cover can be omitted. Screws, but the end caps are expensive to process. The outer side of the transmission end bearing of the small motor is sometimes equipped with a wave spring piece to press the outer ring of the bearing to reduce the axial working clearance of the bearing and reduce the vibration and noise of the motor during operation. In order to reduce noise, low-noise bearings for motors can also be used.
For larger motors, the inner and outer covers of the bearing have oil retaining grooves to prevent dust from penetrating or grease leakage. If one end of the motor is assembled with a column bearing, the bearing caps at both ends can abut the outer ring of the bearing. If ball bearings are used at both ends of the motor, a proper clearance should be left between the outer bearing cap and the outer ring of the bearing. Compensates for the error of the axial dimension chain of the motor and the thermal tight shrinkage of the shaft.
Large motors add a bearing sleeve to the bearing system. When the motor is disassembled, the bearing can be protected from contamination or damage; however, such a structure is expensive to manufacture.
Due to the increasing level of production automation, the required motor can be safely operated without maintenance. The bearing is the weak link in the motor. Nowadays, the small motor mostly uses closed rolling bearing. After the bearing is filled with oil, it will not be replenished. Bearings produced by the manufacturer can generally run continuously for more than two years. The medium-sized motor uses a bearing assembly structure that does not stop for refueling.
In general, new grease is added to the bearing inner cover oil chamber, and the old grease residue is pressed into the outer bearing chamber and then collected in an easily removable container. This refueling device is much better than the oiling device from the bearing cover.