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Products (Machinery - Industrial parts)

Japan-made Bearings & Condition Monitoring Systems for Wind Turbines


Increasing investment is being made into wind power generation, particularly in Europe, and this has driven rapid improvements in the manufacturing technology utilized in wind turbines and generators.

There is great interest in wind power generation in Japan, and research focused on the practical application of wind power generation technologies is gaining momentum. Japan has first been forced to overcome unfavorable climatic and geographical conditions, such as the regular occurrence of typhoons and precipitous landscapes. In recent years, technology that can overcome these issues has been developed in Japan, and the technology featured in Japanese-made wind power generators and parts is enjoying increasing international attention.
One such technological innovation is the development of bearings especially designed for wind turbines.

In this article, this outstanding specialized bearing technology from Japanese manufactures is introduced, together with a condition monitoring system for wind turbines that, like the bearings, can contribute to extending the life span of wind power generators.

High Load Capacity for the large bearings required by wind turbines

There are still only a few bearings manufacturers in the world today able to provide a stable supply of the large bearings required by wind turbines, and, among these, it is Japanese bearings manufacturers that top the field.
The internationally top-class technology currently available from these manufacturers is outlined below.

High Load Capacity Cylindrical Roller Bearings
These bearings have a rating life that is around 1.5 times longer than that of conventional high load type bearings, and also boast a permissible rolling speed that is twice that of conventional high load bearings. These bearings can be used on high speed shafts and having a proven extended rating life. This makes them an ideal choice as bearings for speed-up gears in induction-type wind turbines.
The bearings for large-scale wind turbines must be able to withstand both high loads and high speed rotation. Conventionally, however, bearings have only been able to withstand one or the other, with bearings selected according to the performance was required.
High load capacity cylindrical roller bearings use a ‘rolling element separator’ in between rolling elements. This has increased the load capacity of the bearings, as well as allowing them to withstand the fast rotation of the wind turbines in which they are used.

Large-type insulated ceramic bearings
The use of ceramic balls in the rolling element of bearing prevents electrical corrosion, and increases the life of the lubrication grease by limiting the heat generated inside the bearing. This high-reliability bearing helps to contributes to the reduction of maintenance costs.
Ceramic material has been used in the manufacturing of bearings previously, for example on the surface of bearings as a spray coating. However, the insulatory function of this coating was lost through friction caused by abrasion. These ceramic bearings use ceramic balls, made with silicon nitride, which has been demonstrated in tests to have outstanding properties. Both the inner and outer rings are ceramic, making this bearing entirely ceramic. The special ceramic material used ensures that will remain highly resistant to water and to corrosion, and highly insulating, for an extended period of time.

Spherical roller bearings
Spherical roller bearings are designed especially to optimize the track geometry, resulting in steady and smooth rotation. The allowable aligning angle is 1° or more, and the bearings are also able to accommodate dynamic error and static fitting error to a high level.
The bearing also boasts a large capacity for radial loads.
The central part of the inner ring features an inner rib. Other types are designed to guide the roller smoothly and securely in the face of changes in front wind loads, or to ensure that the internal clearance during operation is always maintained to an appropriate level—this is achieved by a specially determined clearance range.

The Japanese-made bearings introduced above are already being used—and lauded—all over the world. They are certain to impress with their high functionality and performance, realized to levels you are likely yet to experience.

In recent years, wind power generators are increasing in size, and in output level. Increasingly, bearings must be able to withstand ever higher loads—market demand is focusing on large-scale, high performance bearings. Bearings manufacturers in Japan are hard at work developing the technology and products required to meet market requirements now and into the future.

For the stable operation of wind power generators

This condition monitoring system comprises a data collection device and a measurement sensor, as well as software for the control, monitoring and analysis of data. The data collection device is among the smallest in the world (at just 250x290x108mm), helping to keep system space down. This small size also means that the device can be installed in existing nacelles with ease. It has outstanding levels of dust and water-proofing, making it adaptable to a wide range of environmental conditions, including offshore locations (able to withstand temperatures of -20°C—60°C).

The measurement sensor is capable of the automatic diagnosis of measurement data to a high degree of accuracy. The software contained within the system allows remote monitoring of the condition of the generator in real time. 

The features and technologies contained within the system make it possible to identify defects or errors within the various components of a generator as quickly as possible, and also enable the scheduling of maintenance programs. Using the conditioning monitoring system will help to prevent declines in the operational efficiency of wind power generators, as well as significantly reduce the time and cost of maintenance.

26 November, 2012

About the author
Hiromi Jitsukata is a reporter for Japanest NIPPON