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Shanghai Shang Shaft Bearing Quality Inspection Institute Co., Ltd.

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Address: 301 Shangxue Road, Jiading District, Shanghai

Grease Leakage Analysis and Improvement Measures of Wind Turbine Pitch Bearing (2)

2021-07-30 15:09

1. solutions


1 Sealing ring

1.1 selection of reliable sealing ring material

The key performance of domestic sealing ring, such as anti-aging, anti-wear and so on.There is still a certain gap abroad, most of the current wind turbine manufacturers adopt.With a higher cost of imported sealing ring material.


1.2 Improve the structure of the sealing ring

At present, most of the domestic pitch bearing seals use similar doublethe structure of the lip,Simple structure to prevent internal grease leakageThe ability to optimize on the basis of the original structure will be limited.Double Lip Structure Changed to Multi-Lip Structure, at the same timeAdd 2 channels of straight packingSeal Lip Reinforced Leakageeffect.

Outer circle table of the front end of the first oil sealing lip and the inner ring of the pitch bearingThe surface is in close contact, and the end is in close contact with the inner circular surface of the outer ring.The cambered surface on the outside helps to offset the lubrication inside the pitch bearingGrease pressure can prevent grease from sealing lip and inner and outer rings from the firstGap leakage.


The second and third oil sealing lips have a fishtail shape, which is similar to the innerThe sealing groove on the outer surface of the ring is in contact with each other, and there is a small amount of contact between the two.The gap, Ding Qing rubber sealing ring has a certain degree of elasticity, both to protectProve that the pitch bearing rotates normally and can prevent the oil sealing lip from the first channel.The leaking grease continues to leak outward.


The fourth oil sealing lip contacts the groove of the outer ring to prevent changes.The grease leaking from the paddle bearing continues to leak outward.


The shape of the dust lip is fin-shaped, and the outer circular surface of the end and the inner ringThe convex cambered surface of its outer side not only ensures the prevention ofThe dust lip closely abuts against the inner ring and is conducive to processing. Dust-proof liphas the characteristics of two-way protection, which can prevent the leakage of grease to continueLeakage to the outside, but also to prevent dust in the air, impurities or otherHazardous substances enter the pitch bearing, resulting in channel wear orHeat stuck, causing the wind turbine to fail to work normally, even a major accident.


The first and second straight sealing lips are in contact with the outer ring surface, which canPrevent leaking grease from continuing to leak outward.


The boss is located on the main seal body, the upper surface is flat, and at the same timeThere is a space for the installation tool to operate between the dust lips, and the belt can be usedThe operating tool of the roller structure is rolled forward and backward along the upper surface of the boss, andThe sealing ring is compacted to ensure the sealing effect of the sealing ring.


The overall shape of the new leak-proof sealing ring is fishbone, using 14 dust lips, 4 oil sealing lips and 2 straight sealing lips can effectively preventThe grease inside the bearing leaks to the outside.


1.3 reasonable maintenance and timely replacement of damaged or aging sealing ring

Seal rings must be installed or maintained in strict accordance with the specified process,Avoid unqualified installation of sealing ring or damage of sealing ring. Right.Check the sealing ring of grease leakage pitch bearing. If it is found that the sealing ring existsIn the case of aging, serious wear, breakage, warping and deformation, etc., it is necessary to timelyClean the grease leakage and replace the new sealing ring according to the process requirements.


1.4 reducing the size of the stretching head of the hydraulic stretcher

Technical communication with hydraulic stretcher suppliers to reduce tensionExternal dimensions of the extension head to avoid extrusion during field operation of the hydraulic tensionerDamage to the sealing ring; further standardize the field installation process by adding a"Check the distance between the stretching head and the sealing ring during the field operation of the hydraulic stretcher.From the "process.


2 Improve the internal structure of the pitch bearing

2.1 Channel Bottom Trench

Pitch bearing channel structure design not only affects the grease in the shaftThe fluidity of the internal channel also affects the one connected to the channel.The diameter of the section grease hole. The fluidity of the grease and its flow through the cut-off.Face shape and area, the smaller the cross-section, the worse the mobility.


The trench bottom is all circular arc transition, which is actually verified by the wind field.The cross-sectional shape of the groove is not conducive to the flow of grease at the bottom of the groove. ChangeAfter enteringTrench bottom increases the momentgroove, thus increasing the fluidity of the grease. Test resultsshows that,After the channel cross-sectional shape is improved, the grease can flow smoothly from the grease drain hole.Smooth discharge, and the sealing ring is free of bulge and grease leakage..

2.2 Improvement of Bearing Grease Hole Size and Distribution Structure


GB/T 29717-2013 Rolling Bearing Wind Turbine GeneratorSpecifications for Threaded Grease Hole of Pitch Bearing as specified in Group Yaw and Pitch BearingsGenerally M10mm×1 mm,Threaded hole size for M14mm×1.5mm, when there are special requirements, the number and location of grease drainage holesand specifications are determined by the bearing manufacturer in consultation with the wind turbine manufacturer.set.

The entire fat drainage channel is a ladder structure, dividedThe threaded hole part connected with the grease collecting bottle outside the bearing and the light hole part connected with the channel near the inner side of the bearing. The smaller the cross-sectional area through which the grease flows, the greater the resistance during discharge,If the bearing structure allows, increase the diameter and depth of the connecting threaded hole outside the bearing grease discharge hole, and try to make the grease discharge threaded hole close to the channel to reduce the resistance of grease discharge.The diameter of the light hole part of the grease discharge hole close to the channel is generally 9~12mm due to the limitation of the groove width designed at the bottom of the groove. If the structure of the bearing groove bottom is improved and the groove width is increased, the diameter of the light hole part of the grease discharge hole close to the channel can be increased to facilitate grease discharge.


The grease discharge hole and grease injection hole of the pitch bearing are generally spaced apart.Cloth, the axial position of the grease discharge hole is in the center of the channel.


Reasonable selection of grease and centralized lubrication system settings

3.1 Choosing the Right Grease

According to the actual conditions of the pitch bearing, the consistency of the grease andSelect the appropriate grease for its compatibility with the sealing ring. LubricationThe use temperature of grease is -40~150 ℃, and it should have anti-fretting wearIt has good properties such as extreme pressure, water resistance, corrosion resistance and pumping.


3.2 Selection of Appropriate Grease Injection Quantity and Control Strategy of Lubrication System

Mandatory requirementsThe pitch bearing can only be filled with a maximum of 70% of the filling.volume, and use a centralized lubrication systemIt is not recommended to use artificial grease injectionway.


Considering that the pitch bearing is not running or the machine is shut down for a long time.The centralized lubrication system continues according to its preset fixed program.Grease injection, so the control strategy of the centralized lubrication system needs to be optimized.change the grease injection control mode to grease injection during pitch bearing operation (thisThe required grease injection pressure is much less than the sealing pressure of the sealing ring), not shipped.Do not grease when traveling. At the same time, refer to the pitch angle and speed of the pitch bearing.The control strategy is designed for factors such as degree, time and cumulative pitch time.The frequency and time of grease injection are set. In addition, centralized lubricationThe system shall be adjusted according to the external temperature of the site, and shall be lubricated at low temperature.The consistency of the grease is large, and the pumpability is poor. At this time, the grease injection frequency needs to be increased.The consistency of the grease at high temperatures is small and the pumpability is good.Reduce the frequency of grease injection.


For the pressure pump of the centralized lubrication system or the empty in the grease pipeThe problem of grease leakage caused by incomplete evacuation of gas can be used in centralized lubrication.After the system is installed, it will be jointly debugged with the pitch system.Actual operation of the centralized lubrication system to check whether the pitch bearing channelThere is residual air and fully discharged.


3.3 increase waste grease removal system

The working principle of the waste grease removal system is:Hydraulic pump, pressure oil through the power pipe A drive waste oil suction greaseThe waste oil in the bearing is sucked into the cavity of the suction and discharge device, and then divided into control.The box starts the two-position four-way valve, the system reverses, and the pressure oil passes through the power pipe.B drives the waste oil liposuction device to collect the waste grease in the liposuction cavityCollect the waste oil into the oil collecting tank through the waste oil collecting pipe.


In addition, vacuum bags can be used instead of fat collection bottles to collect waste fat,Or shorten the waste grease discharge pipeline, increase the diameter of the nozzle of the grease collection bottle, etc.Methods to improve the waste grease is not easy to discharge the situation.