MiCRoLuBGeaR

For the last 30 years, wind energy industry has kept increasing the energy generated per wind turbine. This power installed per wind turbine leads to an optimization of the maintenance and to the need of an increased reliability; a new technical challenge for wind turbine designers.

A lack of lubrication can bring WTGs to a standstill. The Increased cost of lubricants and maintenance duties, coupled with a higher equipment value, drives the need for automatic and centralized lubrication systems.

Harsh conditions such as vibration, mechanical loads, contamination and moisture cumulatively result in a high wear rate for gears and friction points. Proper Lubrication is absolutely necessary in order to provide the right protection.

A poor preventive maintenance in a wind turbine might lead to continued non-desired breakdowns and the need to apply corrective maintenance. Predictive & preventive maintenance are being optimized in order to maximize energy generation. For this reason new multimegawatt WTGs house autonomous systems that contribute to decrease the maintenance tasks.

By using Automatic Lubrication Systems, the lubricant is automatically delivered in time-controlled and metered quantities to all connected points in the system, while the WTG is in operation. Lubrication “in motion” ensures that the lubricant is optimally and evenly distributed within the bearings.

Pitch Gears systems lack an even distribution of lubricant, since only a 90-degree cog segment is actually used. Automatic Lubrication becomes more difficult by the fact that for around 90% of the production time of a wind turbine the rotor blades remain in what is known as the 0-degree setting and is adjusted by only minimal values. Therefore, two to three teeth of the open gear drive are exposed to extremely high loads while the turbine is in production. Conventional lubrication of this cog segment can only be achieved if the rotor blades turn the complete 90º segment during a maintenance session. However, as maintenance normally cannot be carried out without taking the turbine offline there are only two options for lubricating the rotor blade adjustment gear:

•  Lubrication during the natural idle phases (no wind)
• Compulsory maintenance intervals, associated with additional loss of production

The idea of adapting the lubrication task to natural idle phases is attractive to wind farm operators but not at all to designers or maintenance staff. The fact is that production phases may be extremely long during windy conditions. These periods tend to be longer for offshore plants than in onshore installations. In such cases, the lubrication film could degenerate and fail before the end of the natural wind production phase, thus causing damage to the gear drive.

For gear drive lubrication there are essentially two acceptable methods that can be applied to wind turbines:

• Mechanical pinion gear lubrication
• Spray lubrication using compressed air​

Microlubgear is a novel technology that avoids energy generation loses and lubricates the pitch at 0º position. Microlubgear – combined with a right Automatic Lubrication System – lubricates the tooth in contact while the wind turbine operates and the pitch system is working. 

MICROLUBGEAR is an automatic lubrication device redeemable before two years of operation, just by the increase of energy generated.

MicroLubGear device can be adapted on every platform of WTGs – with electrical pitch system, and also for yaw gears – from serial production or even be retrofitted on operative wind farms. It can be also integrated in automatic lubrication systems based on lube pinion.

The lubricant is pumped from a centralized pump station and distributed to the lube pinion/s and/or MicroLubGear/s installed on the gear. Just a minimum and metered volume of grease reaches MicroLubGear’s inlet – as long as pitch system operates – and throughout integrated microchannels, the lubricant is evenly applied to the tooth flank that is going to be engaged. In this way, MicroLubgear improves the efficiency of the automatic system, restores the grease film on the gear teeth and optimizes the grease consumption.

Suitability:

• Onshore & Offshore WTGs, even under Cold Climate Conditions
• Pitch and Yaw gears

Models:

• Available from 12 module and larger. Manual of operation
• Customizable to each gear width

Patented:  J., Casals-Terré, Farré-Lladós, J."Procedimiento y dispositivo para prevenir el desgaste excesivo en engranajes". PCT/ES2013/070494

Publications:

Farré-Lladós, J., Westerberg, L-G. & Casals, J.New solution to prevent excessive wear in wind turbine gears. 2017In Journal of Mechanical Science and Technology. 31 (2) 797-806

Farré-Lladós, J., Casals-Terré, J., Voltas, J. & Westerberg, L-G.The use of Rapid Prototyping techniques (RPT) to manufacture micro channels suitable for high operation pressures and µPIV. 2016 In : Rapid Prototyping Journal 22 (1), pp. 67-76

Westerberg, L-G., Farré-Lladós, J. & Casals-Terré, J.Grease flow and wall slip effects in elbow channels: analytical modeling and flow measurements using micro PIV. 2015 In : Tribology Letters  57 (3), 30