In the operation of high-speed and high-power motors, when the rotor speed reaches a certain value between 2-2.5 times of the first-order critical speed, the sliding bearing of the motor suddenly experiences severe self-vibration caused by the oil film. Oil film oscillation is the unstable rotation of the center of the spindle journal in the sliding bearing bush caused by the motor running under certain conditions. It is a self-excited oscillation of the oil film, which is often accompanied by low-frequency sound and clear and audible. Sliding bearing self-scoring sound.

Lubrication of lubricating oil film and preventive measures

There are many factors in the oil film oscillation caused by high-speed and high-power motor sliding bearings. After eliminating the oscillation factors caused by the motor itself and the driving equipment and the excitation system, the designer should consider the following measures:

● Designed to appropriately reduce the length of the sliding bearing bush and the shaft-to-diameter ratio to increase the bearing pressure of the sliding bearing unit and enhance the stability of the sliding bearing operation;

●Change the sliding bearing clearance;

● Change the oil grade to change the oil quality and viscosity:

●Increase the sliding bearing bush oil mold, that is, reduce the curvature of the bearing bush side;

● Improve the dynamic balance performance of the rotor of the motor and reduce the unbalanced quality of the rotor residual;

● Revisit the overall installation base design and installation quality.

Sliding bearing lubricant cooling

The operation proves that the high-power motor design adopts the self-lubricating sliding bearing. Although it has many advantages such as simple structure, easy maintenance, and no external factors, due to the size limitation of the standardized structure, some specifications have appeared that the sliding bearing temperature rise exceeds the standard. The problem, especially in the hot seasons in some parts of China, is even more problematic. Therefore, some users have requested to increase the fuel tank and increase the loose ribs.

Under the situation of transformation, a motor supporting company researched and designed a self-lubricating non-standard end cap sliding bearing with an inner U-tube type tube-fin circulating water cooler, placed in front of the end cap sliding bearing. It is a U-tube type gauge water cooler. Its structural design and cooling effect are ideal.

Reprinted from the network