What are the operating characteristics of vertical motors?

Vertical motor thrust bearings (hereinafter referred to as thrust bearings) are mainly used for vertical installation of rotating motors and other equipment. In addition to bearing the axial and radial loads of rotating parts (such as motor rotor), they also need to bear the loads of pump rotating parts and axial water thrust, which is the key support part of the whole pump set. The bearings can be self-lubricating or pressure oil circulation lubrication according to the different working conditions and load selection.

　　Our commonly used thrust bearings are usually self-lubricating, and their cooling is usually natural or by water through a cooler mounted in the upper frame, with the lubricating oil circulating internally. Specifically, the lubricating oil flows into the space between the thrust head and the inner cylinder through the recesses designed in the support plate, enters the working surfaces of the thrust and guide tiles respectively, and then flows out from the oil outlet of the guide bearing housing and the upper frame, where it is cooled by the oil cooler and recirculated.

　　The vertical motor thrust bearing bears the larger weight and axial water thrust of the rotating part of the pump unit. The bearings should be able to start the motor directly without jacking up the rotor and ensure that the pump unit can run safely at low speed without braking device during shutdown; the guide bearings bear the radial mechanical unbalance force and electromagnetic unbalance force of the rotating part of the unit. Thrust and guide bearings require easy installation, maintenance and replacement, and long service life. The structure should also meet the overall requirements of the core pump, and meet the requirements of the number of cold starts and hot starts of the pumping unit per day. Therefore, whether the structural form of the thrust bearing is reasonable plays a vital role in the long-term safe and stable operation of the unit.

　　The structural form of vertical motor thrust bearing can be generally divided into rigid support thrust bearing and elastic support thrust bearing according to the different ways of bearing support. Domestic pump stations, hydropower stations and other related industries have small-capacity motor units supported by rigid supports and elastic pads, while large-capacity and medium-capacity units are supported by elastic oil tanks and balancing blocks. The support structure is an important part of the thrust bearing and has a great influence on the load distribution between the shaft tiles. In addition to meeting the requirements of strength and stiffness, it should ensure that the load is evenly distributed on each tile, easy to manufacture, and easy to install and maintain.

　　In recent years, with the emergence of different types of vertical motor units and the development of technology, elastically supported thrust bearings have been widely used, such as Jiangsu Province Lin Hongdong pumping station and some power plant cooling water circulation pumping stations. Traditional thrust bearings generally use fan-shaped thrust shingles. This type of shaft tile has a wide range of applications. Most of the vertical water pump thrust bearings operating in China use this type of thrust bearing. In addition, large, medium or very large generating units in the hydropower industry have enormous size and weight. Under the premise of meeting the unit pressure requirements on the surface of the shaft shingles, the thrust shingles are fan-shaped, with large areas, narrow shapes and a large number of shingles. However, the larger the area of traditional fan-shaped thrust shingles, the more difficult it is to control the deformation and the higher the operating temperature may be. In practice, it is difficult to control the deformation within a good range.