Motor bearing is an important part in the motor, its performance and stability directly affect the operation of the motor. During the operation of the motor, the bearing will be affected by thermal expansion, resulting in changes in the bearing clearance, which in turn affects the performance and life of the motor. Therefore, thermal expansion compensation for motor bearings is very important. This paper will discuss the thermal expansion compensation method and practice of motor bearing from the principle, method and practice cases.
Thermal expansion refers to the phenomenon that an object increases in size as the temperature increases. In motor bearings, due to the temperature difference between the inner and outer rings and matching tolerances and other factors, the bearing clearance will change. In order to eliminate this effect, the bearing needs to be compensated for thermal expansion. The principle of thermal expansion compensation is to set compensation elements between the inner and outer rings of the bearing to offset the clearance changes caused by thermal expansion.
Method of thermal expansion compensation
Mechanical compensation method
The mechanical compensation method is to compensate the clearance change caused by thermal expansion by adjusting the relative position of the bearing inner and outer rings. The specific methods include adding or reducing gaskets on the inner or outer ring of the bearing, adjusting the preload force of the bearing, etc. The advantage of mechanical compensation method is simple and easy, but the adjustment accuracy is low, and it may need to be adjusted repeatedly.
Hydraulic compensation method
The hydraulic compensation method is to compensate the clearance change caused by thermal expansion by injecting liquid between the inner and outer rings of the bearing. The liquid expands as the temperature rises, thus offsetting the change in bearing clearance. The hydraulic compensation method has the advantages of high compensation precision and strong adaptability, but it needs to consider the sealing and leakage of liquid.
Gas compensation method
The gas compensation method is to compensate the clearance change caused by thermal expansion by filling gas between the inner and outer rings of the bearing. The gas also expands when the temperature rises, thus offsetting the change in bearing clearance. The gas compensation method has the advantages of high compensation precision, strong adaptability, and no need to consider the sealing and leakage of liquid. However, the pressure control and monitoring of gases need to be considered.
Taking a large motor as an example, this paper introduces how to use the method of hydraulic compensation to compensate the thermal expansion of the motor bearing. The speed of the motor is 3000r/min, the rated power is 1000kW, and the working ambient temperature is -20℃~+50℃.
First, the hydraulic compensator is installed on the bearing seat of the motor, and the gap between the inlet and outlet of the compensator and the inner and outer rings of the bearing is connected. Then, inject an appropriate amount of liquid into the compensator, and adjust the pressure of the liquid, so that the bearing at room temperature to maintain the appropriate preload. During the operation of the motor, when the temperature rises, the liquid expands and flows into the bearing clearance, thus counteracting the clearance change caused by thermal expansion. At the same time, by monitoring the pressure and temperature of the liquid, the working state of the bearing can be mastered in real time and adjusted.
It should be noted that when using the hydraulic compensation method, the appropriate liquid and sealing method should be selected, and the cleanliness and lubricity of the liquid should be ensured. In addition, the compensator should be checked and maintained regularly to ensure that it is working properly.
The thermal expansion compensation of motor bearing is one of the important measures to ensure the performance and life of motor. By compensating the bearing for thermal expansion, the influence of temperature difference and fitting tolerance on bearing clearance can be effectively eliminated. In practical applications, appropriate compensation methods and skills can be selected according to the specific situation to ensure that the working condition of the bearing is good. At the same time, attention should be paid to keeping the bearings clean and lubricated to extend their service life.
