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Core technology solutions for wind power bearings

wallpapers News 2020-05-15
With the development of new energy applications, wind energy, which was developed earlier as a new energy source, occupies an increasing proportion in the power grid. At the same time, more and more manufacturers have developed a variety of different wind turbine mainframes. In order to enhance the competitiveness of their products in the market, from the improvement of the transmission chain design to the consideration of the different functions of various parts, they have become Different considerations for the design improvement of wind turbine generators.
The selection of bearings as the main components of wind turbines has always been the biggest concern of main engine manufacturers. Whether it is the design of the bearing itself or the choice of bearing Configuration, it determines the running performance and service life of the main engine of the wind turbine.
The traditional wind turbine bearing configuration is double bearing support. According to the working principle of the wind turbine, the transmission chain usually adopts the following design: main shaft, gearbox (speed increase box), and generator. On the main shaft, the dual-bearing Configuration is a more traditional and commonly used form. The type of bearing used varies according to the design requirements, but usually, the more traditional bearing configuration is a spherical roller bearing configuration or tapered roller bearing Configuration.
The advantage of the dual-bearing Configuration is that the main shaft bearing bears most of the complex wind loads. Except for torque, basically, no other load will be transmitted to the gearbox of the transmission chain, which brings great convenience to the design of the gearbox. But this Configuration also has its own shortcomings, such as a long transmission chain, in addition to the length of the main shaft, the length of the coupling connecting the main shaft, and the gearbox must also be considered. Therefore, in low-power wind turbines, this Configuration is more common. In high-power wind turbines, an excessively long drive chain means greater volume and higher manufacturing costs.
 
The latest spindle bearing configuration solution is single bearing support. With the development of wind turbines, high-power wind turbines have become a market development trend, and higher energy density has also become the goal of various mainframe manufacturers to catch up, which brings great challenges to bearing design.
In addition to the larger contact angle, another significant feature of this bearing is the use of a segmented engineering plastic cage. For the internal components of the bearing, the rolling elements are important load-bearing components, and in addition to maintaining the rolling running state, the cage also has the function of separating the rolling elements to avoid friction between them. The cage is not a stressed component and cannot withstand any form of external force. Therefore, it is often produced with lighter materials, and at the same time, the cage material must meet another requirement, namely, sufficient strength.
1. Larger contact angle
 
Traditional paired (or double-row) tapered roller bearings, and the contact angle is generally only about 20, in addition to ensuring its greater radial load capacity, the bearing's axial load capacity, and the ability to withstand overturning torque have certain limits. Therefore, to ensure that the design can meet the requirements of the application on the main shaft, another bearing must be used as the second fulcrum to bear additional radial forces, and the Configuration of the two bearings can meet the tipping moment of the entire shaft. No deformation will occur.
 
And Nautilus bearings break through the traditional contact angle design and enlarge the contact angle of every single row bearing to 45. Compared with the traditional double-bearing Configuration, the distance between the contact points of the two single-row bearings of the Nautilus bearing is much higher than that of the general tapered roller bearing. The intersection of these two contact points can be used as two. This focal point becomes the point of action to support the operation of the shafting.
 
2. Segmented engineering plastic cage
 
In addition to the larger contact angle, another significant feature of this bearing is the use of a segmented engineering plastic cage. For the internal components of the bearing, the rolling elements are important load-bearing components, and in addition to maintaining the rolling running state, the cage also has the function of separating the rolling elements to avoid friction between them. The cage is not a stressed component and cannot withstand any form of external force. Therefore, it is often produced with lighter materials, and at the same time, the cage material must meet another requirement, namely, sufficient strength. Since the power required for the rotation of the cage during the operation of the bearing is provided by the rolling elements, therefore, the material of the cage needs a certain strength to ensure its normal operation.
 
For wind bearings, in order to ensure that the contact angle connection is sufficient to withstand the forces in the system, the size of the bearing is often very large. At present, the most widely used on the market are bearing products with a diameter of 2 to 2.5 m. Therefore, reducing the weight of the bearing itself has become an urgent technical problem in its design. As the inner and outer rings and rolling elements of the load-bearing parts, in order to ensure the bearing capacity of the bearing, there must be no sloppy in the selection of materials. The engineering plastics used in SKF Nautilus bearings can not only ensure sufficient strength but also have a lightweight, which ensures the rotation performance of the bearing and reduces the internal friction of the bearing. Another typical design is a full-roller bearing design without a cage. Of course, from the perspective of the lower rotational speed of the main shaft bearing, the reduction in the rotation capacity caused by the full roller bearing is not enough to hinder the application of the bearing. However, the friction between the rolling elements is a key that cannot be ignored.
 
The reason for designing the cage in the bearing is to separate the two adjacent rolling elements, to avoid the internal friction of the rolling bearing elements during bearing operation, and to reduce friction and noise. Therefore, although the full-roller bearing has a high load-carrying capacity, on the spindle bearing, it is still not an ideal choice due to the friction inside the rolling body.
 
In addition, another cage design mentioned above is an integrated cage similar to traditional bearings. In SKF Nautilus bearings, there is no choice of the one-piece cage, mainly because its size is too large, its own weight will cause deformation of the cage, and bring more friction between the rolling element and the cage. In addition, as an energy-generating device, an important issue in the design of wind turbines is to increase energy density and minimize the energy loss of their components. From this perspective, the integrated cage also has limitations.
 
Wind turbines, because of their special application conditions, are crucial to the selection of components. According to research reports, by 2012, the installed capacity of wind power will increase from 90,000 MW in 2007 to 290,000MW. Wind turbine manufacturers and operators are increasingly inclined to high-reliability wind turbine generators to achieve a balance between economic and ecological benefits.
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