CN221503449U - Bearing unit - Google Patents

Abstract

The present disclosure relates to a bearing unit, which includes a unit outer cylinder, a unit inner cylinder surrounded by the unit outer cylinder, and a first bearing and a second bearing, wherein the first bearing and the second bearing are located between the unit outer cylinder and the unit inner cylinder and are spaced apart along the axial direction of the bearing unit. The distance between the first bearing and the second bearing is 10% to 40% of the outer diameter of the first bearing and/or the second bearing. By increasing the distance between the two bearings, the bearing load of the blade during operation is reduced, thereby reducing the force on the variable pitch bearing and extending the service life of the variable pitch bearing.

Description

Bearing units

Technical Field

The present disclosure relates to a bearing unit.

Background Art

The function of the variable pitch bearing in the wind power generation system is to connect the blades and the hub and transfer the load on the blades to the hub. When the wind speed is too high or too low, the angle of attack of the airflow on the blades is changed by adjusting the blade pitch, thereby changing the aerodynamic torque obtained by the wind turbine generator set and keeping the power output stable. Therefore, the variable pitch bearing is extremely important for the safe production and reliable operation of wind turbines.

At present, the variable pitch bearings of wind turbines are usually lubricated with grease, and the lubrication method is a centralized lubrication system. At present, wind turbines are getting bigger and bigger, the blades are getting longer and longer, and the blade mass is also getting larger and larger. At present, the length of wind turbine blades can reach more than 120 meters, and the weight of a single blade is nearly 60 tons, and the length and mass of blades are also tending to increase further. However, the current bearing arrangement has a poor force structure, a large bearing diameter, and a relatively high cost.

The forces acting on the pitch bearing are very complex. During operation, the pitch bearing is subjected to the loads caused by aerodynamic force, gravity, centrifugal force and yaw transmitted by the blades. These forces are transmitted to the pitch bearing through the blades and manifest as axial force, radial force and overturning moment. During operation, the bearing is also subjected to the vibration force generated by the coupling of various loads. This vibration force easily causes the bearing to have micro-motion friction and wear, that is, the three micro-motion tribological phenomena of micro-motion wear, micro-motion fatigue and micro-motion corrosion. When the pitch action is not performed, the rolling element inside the pitch bearing usually only reciprocates for a very small distance relative to the raceway surface. In this micro-distance reciprocating motion, micro-motion wear is very likely to occur, forming micro-motion wear particles. If these wear particles enter the contact area between the rolling element and the raceway, abrasive wear will be formed, resulting in further aggravation of the pitch bearing wear and premature failure of the bearing. Therefore, timely removal of the wear particles generated in the contact area between the rolling element and the raceway has a positive effect on reducing the abrasive wear inside the pitch bearing. Further development of micro-motion wear will lead to micro-motion fatigue of the pitch bearing. The three-row roller slewing bearings currently used in large wind turbine blade pitch control cannot be preloaded, so there is a certain amount of clearance when the bearings are running. The existence of the clearance makes the rolling elements in the bearings prone to micro-motion wear.

Under ideal conditions of good lubrication, the occurrence and development of these micro-motion friction wear will be suppressed as much as possible. However, in the absence of lubricant or poor lubrication, it is easy to cause failure of the variable pitch bearing, and then cause failure of the variable pitch system. In severe cases, the outer ring of the bearing will crack, and even a major accident of blade falling may occur.

When the pitch bearing is in normal operation, the pitch adjustment angle is usually 0°-30°. Although the adjustment frequency may be relatively high at times, the speed of the rolling element of the pitch bearing relative to the raceway surface is very low. However, under most operating conditions, the pitch action is relatively rare. At this time, during the operation of the wind turbine, the relative speed between the friction pairs such as the rolling element and the raceway surface of the pitch bearing is very low, or even almost zero, which makes it impossible to form a sufficiently thick fluid lubricant film, that is, it is impossible to have a thick enough fluid lubricant film to separate the friction pairs inside the bearing. Therefore, the lubrication inside the bearing is in a state of boundary lubrication. It is very important to ensure that there is a sufficient amount of lubricant in the contact area between the rolling element and the raceway to form a boundary lubrication film for the lubrication of the pitch bearing.

At present, most of the variable pitch bearings of wind turbines are lubricated by centralized lubrication systems, and the lubricant is grease. After the variable pitch bearing has been running for a period of time, due to the continuous action of gravity and centrifugal force, the shearing action of rolling elements and cages, the vibration caused by the blades' response to wind, and the cumulative effect of time factors, the grease will lose excessive base oil, resulting in insufficient oil content in the grease, reduced lubrication ability, hardening of the grease, and even grease discharge failure of the bearing. If the waste grease cannot be discharged from the bearing cavity in time, the grease will fill and block the inner cavity of the bearing. As the grease continues to be filled, the pressure in the inner cavity will become higher and higher. Excessive pressure will burst and squeeze out the bearing seal ring, causing grease leakage and contaminating the inside of the wind turbine hub. The waste grease accumulates in the bearing cavity, and the metal debris and other contaminants generated during the operation of the bearing will block the oil filling hole and the grease discharge hole, resulting in the inability to pump in new grease, while the waste grease cannot be discharged, which further increases the wear rate of the internal raceway and rolling element of the bearing, shortens the life of the variable pitch bearing, and has a significant impact on the reliable operation of the variable pitch system and wind turbine.

Studies have shown that the iron content of the grease discharged from the in-service variable pitch bearings is very high, and the iron content of some variable pitch bearing grease samples is even more than 1%. Excessive metal particle content in the grease will accelerate the oxidation of the grease, harden and compact, and destroy the fiber structure of the grease, making it unable to "lock" the base oil in the grease, resulting in a significant drop in the oil content in the grease, causing poor lubrication of the variable pitch bearing and making the variable pitch system unable to work properly.

If the pitch bearing fails and needs to be replaced, it will bring huge economic losses to the wind turbine maintenance unit, especially for offshore wind turbines, where the replacement of the pitch bearing will bring even greater economic losses.

Therefore, replacing the grease lubrication of the variable pitch bearing with lubricating oil lubrication has great benefits for the friction pair in the wind turbine variable pitch bearing, but after replacing it with lubricating oil lubrication, it will face the problem of lubricating oil leakage. Therefore, in order to solve the risk and problem of lubricating oil leakage in the variable pitch bearing unit lubricated with lubricating oil, the sealing structure of the variable pitch bearing unit needs to be redesigned.

Utility Model Content

In response to the problems and needs mentioned above, the present disclosure proposes a bearing unit that is particularly suitable for a wind turbine pitch system, which can not only effectively alleviate the technical problems mentioned above, but also bring other technical effects due to the following specific features.

The bearing unit proposed in the present disclosure includes a unit outer cylinder, a unit inner cylinder surrounded by the unit outer cylinder, and a first bearing and a second bearing, wherein the first bearing and the second bearing are located between the unit outer cylinder and the unit inner cylinder and are spaced apart in the axial direction of the bearing unit. The distance between the first bearing and the second bearing is 10% to 40% of the outer diameter of the first bearing and/or the second bearing.

Preferably, the bearing unit is provided with one or more lubricating oil delivery paths for delivering lubricating oil to the first bearing and/or the second bearing.

Preferably, each lubricating oil delivery path comprises a lubricating oil delivery passage passing through the unit outer cylinder.

Preferably, each lubricating oil delivery path further comprises an oil injection piece communicated with the lubricating oil delivery channel, wherein the oil injection piece at least partially extends around the unit inner cylinder and is provided with a plurality of oil injection ports.

Preferably, the oil injection piece is a hollow annular structure surrounding the unit inner cylinder.

Preferably, the lubricating oil delivery path includes a first lubricating oil delivery path and a second lubricating oil delivery path for delivering lubricating oil to the first side and the second side of the first bearing, respectively, and a third lubricating oil delivery path and a fourth lubricating oil delivery path for delivering lubricating oil to the first side and the second side of the second bearing, respectively.

Preferably, the second lubricating oil delivery path and the third lubricating oil delivery path share a common lubricating oil delivery passage passing through the unit outer cylinder.

Preferably, the bearing unit further comprises a compressed air conduit passing through the unit outer cylinder to deliver compressed air to the space between the first bearing and the second bearing.

Preferably, the inner wall of the unit outer cylinder is provided with a first shoulder and a second shoulder for mounting the first bearing and the second bearing, and the outer wall of the unit inner cylinder is provided with a third shoulder for mounting the second bearing. The bearing unit also includes a positioning ring surrounding the unit inner cylinder at the end of the unit inner cylinder close to the first bearing. The second bearing abuts between the second shoulder and the third shoulder, and the first bearing abuts between the first shoulder and the positioning ring.

Preferably, the bearing unit further comprises an inner spacer ring surrounding the unit inner cylinder, and two ends of the inner spacer ring abut against the first bearing and the second bearing respectively.

The best embodiments for implementing the present disclosure will be described in more detail below with reference to the accompanying drawings so that the features and advantages of the present disclosure can be easily understood.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments of the present disclosure are briefly introduced below. The drawings are only used to show some embodiments of the present disclosure, but not to limit all embodiments of the present disclosure thereto.

FIG1 shows a schematic diagram of a bearing unit according to a first embodiment of the present disclosure;

FIG2 shows a partial enlarged view of a bearing unit according to a first embodiment of the present disclosure;

FIG3 shows another partial enlarged view of the bearing unit according to the first embodiment of the present disclosure;

4 and 5 are schematic diagrams of oil injection members that can be used in the bearing unit of the present disclosure;

FIG6 is a schematic diagram of a gland that can be used for a bearing unit of the present disclosure;

FIG7 shows a schematic diagram of a bearing unit according to a second embodiment of the present disclosure;

8 and 9 are schematic diagrams showing a sleeve of a bearing unit according to a second embodiment of the present disclosure;

FIG10 shows a partial enlarged view of a bearing unit according to a second embodiment of the present disclosure;

FIG11 is a schematic diagram of a gland that can be used for a bearing unit of the present disclosure;

12 and 13 show two skeleton sealing solutions proposed in the present disclosure;

FIG14 is a schematic diagram showing the sealing structure on the hub side in the solution of FIG12 ;

FIG15 is a schematic diagram showing the sealing structure of the blade side in the solution of FIG12 ;

FIG16 is a schematic diagram showing the sealing structure on the hub side in the solution of FIG13 ;

FIG17 is a schematic diagram showing the sealing structure of the blade side in the solution of FIG13 ;

FIG18 shows an overall view of a bearing unit using a DF type metal face seal;

FIG19 shows a sealing structure on the hub side of the bearing unit of FIG18 ;

FIG20 shows a sealing structure on the blade side of the bearing unit of FIG18;

FIG. 21 shows a solution using a DO type metal face seal.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the technical solution of the present disclosure clearer, the technical solution of the embodiment of the present disclosure will be clearly and completely described in conjunction with the drawings of the specific embodiments of the present disclosure. The same figure marks in the drawings represent the same parts. It should be noted that the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

Compared to the embodiments shown in the drawings, feasible embodiments within the scope of the present disclosure may have fewer components, other components not shown in the drawings, different components, differently arranged components, or differently connected components, etc. In addition, two or more components in the drawings may be implemented in a single component, or a single component shown in the drawings may be implemented as multiple separate components.

Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons of ordinary skill in the field to which the present disclosure belongs. The words "first", "second" and similar words used in the patent application specification and claims of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not necessarily indicate a quantity restriction. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

The bearing disclosed in the present invention is particularly suitable for a variable pitch bearing of a wind turbine, and the application characteristics of the variable pitch bearing in a wind turbine will be particularly introduced below. However, it is worth noting that the application of the bearing unit disclosed in the present invention is not limited to wind turbines.

The variable pitch bearing in the wind turbine connects the blades and the hub, undertakes the blade pitch function, controls the wind force on the blade, and is an important component of the variable pitch system of the wind turbine. The alternating and vibrating loads on the variable pitch bearing will cause a small relative reciprocating motion between the cage, rolling element, and raceway of the variable pitch bearing in a static or slowly swinging state. This relative reciprocating motion is very likely to cause three micro-motion tribological phenomena inside the variable pitch bearing: micro-motion wear, micro-motion fatigue, and micro-motion corrosion. In addition, the structural arrangement of the commonly used variable pitch bearing will cause it to be subjected to a changing overturning moment during operation, resulting in the variable pitch bearing force in a constant periodic change process, and due to the short force arm, the bearing rolling element will be subjected to a large load. In addition, due to the response of the blade to the wind, the blade will also vibrate, and this vibration will be transmitted to the rolling element of the variable pitch bearing, resulting in frequent, reciprocating and random micro-motions between the rolling element and the raceway, which will lead to the occurrence of micro-motion wear, micro-motion fatigue and micro-motion corrosion, and the appearance of micro-motion wear particles. The wear particles generated by the micro-motion wear in the pitch bearing will be wrapped by the grease and stay near the contact area between the rolling element and the raceway, so that these contact areas cannot get enough lubricating oil in time, resulting in poor lubrication. After a period of use, the grease is very likely to harden and lose the base oil, resulting in poor lubrication of the pitch bearing.

To this end, the present disclosure proposes a bearing unit that uses two bearings to increase the distance between the two bearings to reduce the bearing load of the blade during operation, thereby reducing the force on the variable pitch bearing and extending the service life of the variable pitch bearing. In addition, the bearing unit is lubricated with circulating lubricating oil. According to some embodiments, the bearing unit is equipped with a circulating lubricating oil lubricated pipeline, a compressed air pipeline, a special sealing structure, etc., to achieve micro-circulating oil lubrication, which can prevent the variable pitch bearing from having problems caused by oil deficiency or insufficient lubricating oil between operations. The wear particles generated in the bearing are discharged in time through the flow of lubricating oil to improve the lubrication reliability of the variable pitch bearing and extend the service life of the variable pitch bearing.

Specifically, during the operation of the variable pitch bearing, due to the change in the position of the blade in the vertical direction along the transmission chain of the wind turbine, for example, due to the clockwise movement of the blade with the transmission chain as the center, the variable pitch bearing bears loads caused by aerodynamics, loads caused by gravity (radial loads and axial loads), loads caused by centrifugal force, loads caused by yaw, etc. The torque acting on the bearing includes the bending moment of the variable pitch bearing caused by the blade gravity (periodic changing torque), the overturning moment caused by the centrifugal force, the overturning moment caused by the yaw, etc. When the blade is at the 12 o'clock and 6 o'clock positions, the force on the variable pitch bearing is the combined force of the blade's windward force and the blade's gravity. When the variable pitch bearing is at the 3 o'clock and 9 o'clock positions, the force on the variable pitch bearing is the blade's windward force and the bending moment force generated by the blade's gravity. In the existing bearing arrangement, the distance between the force-bearing rolling element rows is relatively close, resulting in a relatively large load on the variable pitch bearing. The bearing unit structure proposed in the present disclosure includes a unit outer cylinder 1 and a unit inner cylinder 2 surrounded by the unit outer cylinder 1, and the first bearing 3 and the second bearing 4 are located between the unit outer cylinder 1 and the unit inner cylinder 2, and are spaced apart along the axial direction of the bearing unit. By designing the length of the unit inner cylinder 2 and the unit outer cylinder 1 and the relevant positioning structure for installing the bearing, the distance between the bearings can be greatly increased, that is, the distance between the force-bearing rolling body rows is increased, and the bearing load of the blade during operation is reduced. For example, the distance between the first bearing 3 and the second bearing 4 can be 10% to 45% of the outer diameter of the first bearing 3 and/or the second bearing 4. Preferably, the distance between the two bearings can be 15% to 40%, 20% to 35%, or 25% to 30% of the outer diameter of the first bearing 3 and/or the second bearing 4. In other embodiments, the distance between the two bearings can be 0.5 meters to 2 meters, or 1 meter to 1.5 meters, etc. It can be seen that the scheme of the present disclosure makes the spacing between the bearings farther, the bearing force is small, more reasonable, and the life is longer. At the same time, the bearing size is reduced, the bearing procurement cost is reduced, the blade root size is reduced, the blade weight is reduced, the wind turbine weight is reduced, and the wind turbine manufacturing cost is reduced. In the present disclosure, the distance between the first bearing and the second bearing refers to the distance between the two sides of the two bearings that are close to each other.

FIG. 1 is a schematic diagram of a bearing unit according to a first exemplary embodiment of the present disclosure, which shows the basic structure of the bearing unit, including a unit outer cylinder 1, a unit inner cylinder 2 surrounded by the unit outer cylinder 1, and a first bearing 3 and a second bearing 4 located between the unit outer cylinder 1 and the unit inner cylinder 2 and spaced apart along the axial direction of the bearing unit. The first bearing 3 and the second bearing 4 shown in the figure are tapered roller bearings, and the first bearing 3 and the second bearing 4 can be of the same size or of different sizes. If they are of different sizes, it is preferred that the bearing on the hub side (bearing 3 in FIG. 1) is larger. The first bearing and the second bearing are preferably arranged back to back and face to face, because the rigidity of the back-to-back bearing arrangement is better. The bearing unit may also include related components for bearing positioning and internal clearance, seals and related components, lubrication pipelines (oil inlet pipelines, oil return pipelines) mentioned below, positive pressure protection air pipelines, etc. For monitoring needs, multiple miniature cameras (not shown in the figure) can also be installed in the bearing unit to perform online video monitoring on the raceway surfaces of the first bearing 3 and the second bearing 4, respectively.

In Figure 1, the left side of the bearing unit is the hub side, and the right side is the blade side. The left end of the unit outer cylinder 1 may include a bolt hole to connect the bearing unit to the wind turbine hub by bolts. The right end of the unit inner cylinder 2 may also be provided with a bolt hole for connecting the pitch bearing unit inner cylinder 2 to the wind turbine blade by bolts. The specific size and number of the bolt holes of the unit outer cylinder 1 and the unit inner cylinder 2 are related to their forces and applications, and are not limited in this disclosure. The two bearing inner rings on the blade side can also be made integral with the blade.

Preferably, the inner wall of the unit outer cylinder 1 is provided with a first shoulder 103 and a second shoulder 104 for mounting the first bearing 3 and the second bearing 4, and the outer wall of the unit inner cylinder 2 is provided with a third shoulder 203 for mounting the second bearing 4. The bearing unit also includes a positioning ring 503 surrounding the unit inner cylinder 2, and the positioning ring 503 abuts against the first bearing 3 and can be regarded as a fourth shoulder. The second bearing 4 abuts between the second shoulder 104 and the third shoulder 203, and the first bearing 3 abuts between the first shoulder 103 and the positioning ring 503. By providing the first shoulder 103, the second shoulder 104, the third shoulder 203 and the positioning ring 503, the positioning of the two bearings can be achieved with a simple structure, and the installation is convenient.

As shown in Fig. 2, the positioning ring 503 is preferably installed to the unit inner cylinder 2 through the gland 502 and with the aid of fasteners such as screws. Fig. 6 shows the structure of the gland 502, wherein the gland is generally a circular sheet structure and may be provided with a plurality of mounting holes 502A, and the number of mounting holes 502A may be multiple and they are evenly arranged in a concentric circle structure.

Preferably, the bearing unit further comprises an inner spacer 504 surrounding the unit inner cylinder 2, and the first bearing 3 and the second bearing 4 respectively abut against two ends of the inner spacer 504. The provision of the inner spacer 504 makes the axial positioning of the first bearing 3 and the second bearing 4 more stable.

When the blade is at the 12 o'clock position, the weight of the blade is transferred from the blade to the third shoulder 203, and then to the second bearing 4 through the third shoulder 203, and then to the first shoulder 103 of the unit outer cylinder 1, and then to the hub by the unit outer cylinder 1. When the blade is at the 6 o'clock position, the weight of the blade is transferred from the pressure cover 502, the positioning ring 503, and the first bearing 3 to the variable pitch unit outer cylinder 1, and finally to the hub. In the process of the blade running from the 12 o'clock position to the 6 o'clock position, the weight of the blade changes from being fully borne by the second bearing 4 to being borne jointly by the second bearing 4 and the first bearing 3, and then to being fully borne by the first bearing 3. In the process of the blade running from the 6 o'clock position to the 12 o'clock position, the weight of the blade changes from being fully borne by the first bearing 3 to being borne jointly by the first and second bearings 4, and then to being fully borne by the second bearing 4. Using the bearing unit structure of the present invention, the weight of the blade can be well borne.

In the preferred embodiment of the present disclosure, the two bearings are preferably tapered roller bearings installed back to back. Alternatively, a combined bearing arrangement of tapered roller bearings, deep groove ball bearings + deep groove ball bearings, angular contact bearings + angular contact bearings, four-point angular contact bearings + four-point angular contact bearings, spherical roller bearings + spherical roller bearings, etc., which can withstand both axial forces and radial forces, can also be used. Among them, the bearing inner ring of the second bearing 4 on the blade side can be made integral with the blade.

Another important advancement of the present disclosure is to change the lubrication method of the variable pitch bearing to lubricating oil lubrication, and to provide the bearing unit with a lubricating oil delivery path for delivering lubricating oil or oil-gas to the first bearing 3 and/or the second bearing 4, thereby solving the problem of oil deficiency and/or insufficient base oil supply in the grease lubricating the variable pitch bearing. By continuously supplying lubricating oil internally, micro-motion tribological behaviors such as severe micro-motion wear, micro-motion fatigue and micro-motion corrosion due to lack of lubricating oil or insufficient lubricating oil in each contact area between the rolling element and the raceway in the bearing are prevented. Through the flow of lubricating oil, the wear particles generated in the bearing are brought out, the accumulation of wear particles in the bearing is prevented, and the secondary abrasive wear hazards caused by the accumulated wear particles in the bearing are reduced, so as to improve the reliability of the variable pitch bearing and the variable pitch system. Due to the use of lubricating oil lubrication, the detection and monitoring of the variable pitch bearing becomes easier and more accurate.

In the present disclosure, the number of lubricating oil delivery paths may be multiple. The form of the lubricating oil delivery path is not limited, and may be a through hole or channel formed in the unit inner cylinder 2 and the unit outer cylinder 1 of the bearing unit to allow the lubricating oil to flow through, or may be a special pipe at least partially disposed in the unit inner cylinder 2 and the unit outer cylinder 1, or a combination of the two.

Preferably, the lubricating oil delivery path also includes an oil injection piece connected to the lubricating oil delivery channel, and the oil injection piece extends at least partially around the unit inner cylinder 2 and is provided with a plurality of oil spray ports. The oil injection piece is preferably a hollow annular structure surrounding the unit inner cylinder 2. Alternatively, the oil injection piece may be a hollow arc-shaped structure of multiple segments surrounding the unit inner cylinder 2. The lubricating oil flows to the oil injection piece via the lubricating oil delivery channel, and flows to the first bearing 3 and/or the second bearing 4 via a plurality of oil spray ports. Figures 4 and 5 are schematic structural diagrams of a preferred oil injection piece, which is a whole circular structure, also referred to as an oil injection ring 901 in the following questions. The oil injection ring 901 may have one or more inlets 901A and a plurality of oil spray ports 901B. Preferably, the number of oil spray ports on the oil injection ring is greater than the number of bearing rolling elements lubricated by it.

1 , the lubricating oil delivery path includes a first lubricating oil delivery path 401 and a second lubricating oil delivery path 402 for delivering lubricating oil to the first side (i.e., the left side in the figure) and the second side (i.e., the right side in the figure) of the first bearing 3, respectively, and a third lubricating oil delivery path 403 and a fourth lubricating oil delivery path 404 for delivering lubricating oil to the first side (i.e., the left side in the figure) and the second side (i.e., the right side in the figure) of the second bearing 4, respectively. Such an arrangement enables each bearing to be well lubricated.

Preferably, the second lubricating oil delivery path 402 and the third lubricating oil delivery path 403 share a common lubricating oil delivery channel 440 that passes through the unit outer cylinder 1. At the same time, a flow tube 450 extending parallel to the axial direction of the bearing unit may be provided at the end of the common lubricating oil delivery channel 440, and both ends of the flow tube 450 terminate at oil injection rings 901 for two bearings, so that the lubricating oil from the common lubricating oil delivery channel 440 is delivered to the first bearing 3 and the second bearing 4 in two directions, respectively.

Preferably, the bearing unit further comprises a compressed air conduit 105 passing through the unit outer cylinder 1 to deliver compressed air to the space between the first bearing 3 and the second bearing 4. The number of compressed air conduits 105 in the bearing unit may be one or more. The compressed air pipe can supply clean compressed air into the bearing unit, achieve a micro-positive pressure in the pitch bearing unit, prevent external water vapor and pollutants from invading the pitch bearing unit, and also help to press the lubricating oil in the pitch bearing unit back to the lubrication system. According to one embodiment, the main body of the compressed air conduit 105 may be a channel located in the unit outer cylinder 1. According to another embodiment, the compressed air conduit 105 may include an independent conduit at least partially located in the unit outer cylinder 1. Among them, the opening of the compressed air conduit 105 may be located at a position between the first bearing 3 and the second bearing 4.

Figures 2 and 3 show the enlarged structure of the oil return pipe area on the hub side and the blade side, respectively. A sealing structure may be provided in this area, but the specific structure of the sealing structure is not shown in the figure, and only the location of the sealing structure is marked with areas 605 and 705.

As shown in FIG2 , the end cover 602 can be fixed to the unit outer cylinder 1 by screws 601 or similar fasteners. The lubricating oil return pipe 604 extends through the end cover 602 to allow the lubricating oil in the bearing unit to return to the oil tank of the lubricating system with the assistance of compressed air. An O-ring can be provided between the end cover 602 and the unit outer cylinder 1 to prevent the lubricating oil in the pitch bearing unit from leaking between the end cover 602 and the unit outer cylinder 1. As shown in FIG3 , the end cover 702 can be fixed to the unit outer cylinder 1 by screws 701 or similar fasteners. The lubricating oil return pipe 704 extends through the end cover 702 to allow the lubricating oil in the bearing unit to return to the oil tank of the lubricating system with the assistance of compressed air. Among them, for the return of the lubricating oil, negative pressure oil return, gravity oil return, positive pressure oil return or a combination of these methods can also be used simultaneously.

2 and 3, another O-ring may be provided between the clearance-fitted positioning ring 503 and the unit inner barrel 2 to prevent the lubricating oil in the bearing unit from leaking from between the positioning ring 503 and the unit inner barrel 2. An O-ring may be provided between the end cover 702 and the unit outer barrel 1 to prevent the lubricating oil in the pitch bearing unit from leaking from between the end cover 702 and the unit outer barrel 1.

The lubricating oil circulation structure disclosed in the present invention has the following technical effects: 1. The variable pitch bearing is in a state of trace circulating oil, and the lubrication effect becomes very good. There will be no poor lubrication due to lack of oil or insufficient oil content of the grease, which greatly improves the reliability of the variable pitch bearing. 2. The variable pitch bearing is lubricated with trace circulating oil. Measures such as lubricating oil cleaning, water removal, moisture intrusion control, and oil quality status monitoring are set in the circulating oil system, which greatly improves the reliability of the system, the predictability of system failures, and the identifiability of failures. It is beneficial to take relevant remedial measures when the variable pitch bearing fails in the early stage. Reduce the losses caused by the failure of the variable pitch system. 3. The micro-motion wear particles in the variable pitch bearing can be discharged more timely, reducing the secondary damage to the bearing. 4. After adopting the form of circulating oil lubrication, an appropriate filter is configured in the circulating oil system to ensure that the circulating oil is at a higher level of cleanliness, thereby improving the service life and reliability of its variable pitch bearing.

FIG7 shows a schematic diagram of a bearing unit according to a second embodiment of the present disclosure. Compared with the first embodiment, the main difference lies in the different positioning method of the first bearing 3 on the left side (hub side), including the different structures of the pressure cover 502 and the positioning ring 503. FIG8 and FIG9 show the positioning ring 503 in this embodiment, which is different from the structure of the positioning ring in the first embodiment. In this embodiment, the positioning ring 503 is an annular structure with oil injection and drawing functions. 503A is a disassembly process hole with internal threads. 503B1, 503B2, and 503B3 are three oil injection holes with threads, and 503C1, 503C2, and 503C3 are three oil channels set in the sleeve, which are placed at different axial positions on the inner surface of the positioning ring 503 and are full-circle channels. The purpose is to establish a high-pressure oil film between the unit inner tube 2 and the positioning ring 503 through different oil injection holes and their corresponding oil channels when the positioning ring 503 is disassembled to different positions.

FIG10 shows a partial enlarged view of the oil return pipe area on the hub side, and the same structure as in the first embodiment is not repeated. FIG11 is a schematic diagram of the structure of the gland 502. Referring to FIG11, the gland 502 includes a mounting hole 502A processed on the gland 502, and the screw 501 is locked on the unit inner cylinder 2 through the mounting hole 502A. The number of mounting holes 502A can be multiple, and they are evenly arranged in a concentric circle structure. Different from the overall gland in the first embodiment, the gland also includes a screw process hole 502B processed on the gland, which serves as a tool when disassembling the positioning ring 503 and the first bearing 3.

When disassembling the positioning ring 503 and the first bearing 3, remove the screws in the mounting hole 502A of the gland, pass the screw process hole 502B with a long bolt, screw it into the hole 503A of the positioning ring 503 and tighten it, and install a nut on the other end of the bolt. After all the long screws are installed, the gland 502 and the positioning ring 503 are connected together. At this time, a certain number of hydraulic cylinders are installed between the gland 502 and the positioning ring 503. At the same time, the high-pressure oil pipe of the manual or electric high-pressure oil pump is connected to the oil filling holes 503B1, 503B2, and 503B3, and oil is injected into these three oil filling holes under pressure, so that high-pressure oil is generated in the oil passages 503C1, 503C2, and 503C3. The high-pressure oil separates the inner surface of the positioning ring 503 and the unit inner tube 2, reducing the disassembly resistance. At this time, pressurize the hydraulic cylinder, so that the positioning ring 503 and the first bearing 3 can be easily disassembled.

In the present disclosure, the pitch bearing unit can be driven by different means such as a gear reduction mechanism, a hydraulic structure, an electric push rod, a pulley, etc. If a gear drive mechanism is used, the gear can be connected to the unit inner tube 2 of the pitch bearing unit.

The skeleton seal solution for solving the lubricating oil sealing problem is introduced below with reference to Figures 12-17. The special seal design can prevent particles in the bearing unit from invading the sealing structure, and solve the possible adverse effects of micro-wear particles on the metal surface contact seal that may cause lubricating oil leakage. A pipeline for lubricating the skeleton seal is set in the sealing structure, and the seal is ensured to be in a good lubricated state through the lubricating oil supply. At the same time, the seal lubrication system can be designed as an oil-gas lubrication system or an oil mist lubrication system to ensure that the seal structure is in a positive pressure state, and the wear particles generated in the bearing cannot invade the seal structure.

The difference between Figure 12 and Figure 13 is that there is no oil injection ring for lubricating the seal in Figure 12, while an oil injection ring for lubricating the seal is provided in Figure 13 to lubricate the sealing lip. Providing an oil injection ring can reduce the number of lubricating oil pipelines in the sealing system, making the structure simpler and the processing more convenient.

FIG14 is a schematic diagram of the sealing structure on the hub side in the scheme of FIG12, which corresponds to the area in the circle on the left side of FIG12. In the figure, 1501A is a fixing screw, which is used to fix the retaining ring 1502A on the unit inner cylinder to achieve axial positioning of the first bearing and the second bearing on the unit inner cylinder to prevent their axial movement. The sealing member 1607 plays a sealing role. The sealing ring can be a molded seal or a turned seal. The sealing member 1607 can be integral or split. The material of the sealing ring can be a rubber material suitable for shaft sealing, such as nitrile rubber, hydrogenated nitrile rubber, fluororubber, silicone rubber, polyurethane, etc. To ensure good sealing, it is best to use a seal with spring preload. The sealing member 1607 can be with a steel frame or without a steel frame.

In FIG. 14 , 1606 is a sealing fixture, including a baffle 1606A and a bolt 1606B. The sealing member 1607 is installed in the space between the sealing fixture 1606 and the sealing seat 1605, and is fixed by the baffle 1606A and the bolt 1606B. FIG. 14 shows that one sealing ring is installed, but in actual operation, two or more sealing rings can also be installed. In FIG. 14 , the flange 1602 and the sealing seat 1605 are made into one piece, and in actual design, they can also be made into separate structures, but in the case of a separate structure, it is necessary to ensure that the sealing seat 1605 can achieve axial positioning and cannot move axially.

In FIG14 , the sealing seat 1605 is fixed to the outer cylinder of the pitch bearing unit by screws 1601. 1608 is a pipeline for lubrication and air sealing, which includes: a lubricating oil gas inlet 1608A, a pipeline 1608B processed in the seal 1605, and a lubricating oil gas outlet 1608C. After the lubricating oil gas comes out of the outlet 1608C, it lubricates the lip of the seal 1607, and the compressed air is exhausted into the bearing unit through the passage 1610 between the sealing seat 1605 and the baffle 1609. There can be multiple lubrication and air sealing pipelines, which are evenly distributed on the sealing seat with flange edges to lubricate the lips of the seal 1607 located at different positions.

In FIG. 14 , the purpose of the spacer 1611 , the spacer 1504 and the baffle 1609 is to prevent contaminants in the pitch bearing unit from invading the lip of the seal, causing wear of the lip of the seal 1607 and resulting in seal failure.

In Figure 14, the function of O-ring 1603A is to prevent the lubricating oil from leaking from the mating surface between the sealing seat 1605 and the outer cylinder of the pitch bearing unit. The function of O-ring 1603B is to prevent the lubricating oil from leaking from the spacer 1611 and the inner cylinder of the pitch bearing unit.

FIG15 shows a schematic diagram of the sealing structure on the blade side in the scheme of FIG12, which corresponds to the area in the circle on the right side of FIG12. In the figure, 1501B is a fixing screw, which is used to fix the retaining ring 1502B on the inner cylinder of the unit to achieve axial positioning of the first bearing and the second bearing on the inner cylinder of the unit to prevent their axial movement. The sealing member 1707 plays a sealing role. The sealing ring can be a molded seal or a turned seal. The sealing ring can be integral or split. The material of the sealing ring can be nitrile rubber, hydrogenated nitrile rubber, fluororubber, silicone rubber, polyurethane and other rubber materials suitable for shaft sealing. To ensure good sealing, it is best to use a seal with spring preload. The sealing ring can be with or without a steel frame.

In FIG. 15 , 1706 is a sealing fixture, including a baffle 1706A and a screw 1706B. The sealing member 1707 is installed in the space between the sealing fixture 1706 and the sealing seat 1705, and is fixed by the baffle 1707A and the screw 1706B. FIG. 15 shows that one sealing ring is installed, but in actual operation, two or more sealing rings can also be installed. In FIG. 15 , the flange 1702 and the sealing seat 1705 are made into one piece, and in actual design, they can also be made into separate structures, but in the case of a separate structure, it is necessary to ensure that the sealing seat 1705 can achieve axial positioning and cannot move axially.

In FIG15 , the sealing seat 1705 is fixed to the unit outer cylinder of the pitch bearing unit by screws 1701. 1708 is a lubrication and gas sealing pipeline, including a lubrication oil gas inlet 1708A, a pipeline 1708B processed in the seal, and a lubrication oil gas outlet 1708C. After the lubrication oil gas comes out of the outlet 1708C, it lubricates the lip of the seal 1707, and the compressed air is exhausted into the bearing unit through the passage 1710. There can be multiple lubrication and gas sealing pipelines 1708, which are evenly distributed on the sealing seat with the flange edge 1702 to lubricate the lips of the seal 1707 located at different positions.

In FIG. 15 , a spacer 1711 and a baffle 1709 are used to prevent contaminants in the pitch bearing unit from invading the lip of the seal 1707 , causing wear of the lip of the seal 1707 and resulting in seal failure.

In Figure 15, O-ring 1703A is used to prevent lubricating oil from leaking from between sealing seat 1705 and the mating surface of the unit outer cylinder. O-ring 1703B is used to prevent lubricating oil from leaking from between spacer 1711 and the inner cylinder of the pitch bearing unit.

Refer to Figures 16 and 17 below, which respectively show the sealing structure on the hub side and the blade side in the scheme of Figure 13. Compared with the schemes of Figures 12, 14, and 15, some optimizations have been made to the lubricating oil distribution of the sealed bearing, and a lubricating oil and gas distribution pipe has been added. The other parts are the same.

FIG16 corresponds to the area in the circle on the left side of FIG13 , and compared with FIG14 , a lubricating oil and gas distribution pipe 1608D is added. Multiple holes for oil and gas outlet can be machined on this distribution pipe 1608D to achieve lubrication of multiple points on the lip of the seal 1607, making the lubrication of the seal 1607 better. At the same time, due to the existence of this lubricating oil and gas distribution pipe, fewer lubricating oil pipes can be machined on the seal seat to meet its lubrication needs.

FIG17 is a schematic diagram of the sealing structure on the blade side, which corresponds to the area in the circle on the right side of FIG13. Compared with FIG14, a lubricating oil gas/oil mist distribution pipe 1708D is added. Multiple holes for oil gas/oil mist can be machined on this distribution pipe 1708D to achieve lubrication of multiple points on the lip of the seal 1707, so that the lubrication of the seal 1707 is better. At the same time, due to the existence of this lubricating oil gas distribution pipe, fewer oil-gas/oil mist pipelines can be machined on the seal seat to meet its lubrication needs.

The above-mentioned skeleton sealing scheme disclosed in the present invention can have the following technical effects: 1. The variable pitch bearing is in a state of trace circulating oil, and the lubrication effect becomes very good. There will be no poor lubrication due to lack of grease or insufficient oil content, which greatly improves the reliability of the variable pitch bearing. 2. The variable pitch bearing is lubricated with trace circulating oil. Measures such as lubricating oil cleaning, water removal, moisture intrusion control, and oil quality status monitoring are set in the circulating oil system to greatly improve the reliability of the system, the predictability of system failures, and the identifiability of failures. It is better to take precautionary measures in the early stage of variable pitch bearing failure. Reduce losses caused by failures of the variable pitch system. 3. The rubber seal can ensure that the lubricating oil does not leak during the operation of the variable pitch bearing unit. The use of turned seals makes maintenance and replacement easier.

The following text introduces metal surface sealing solutions for solving the lubricating oil sealing problem with reference to Figures 18 to 21. These solutions solve the sealing problem of bearing units lubricated with lubricating oil through metal surface contact sealing, and through special design, prevent particles in the bearing unit from invading the sealing structure, and solve the possible adverse effects of micro-wear particles on the metal surface contact seal that may cause lubricating oil leakage. A lubrication pipeline for the metal surface seal is set in the sealing structure, and the metal surface is ensured to be in a good lubricated state by regularly adding lubricating oil. At the same time, the sealing lubrication system can be designed as an oil-gas lubrication system or an oil mist lubrication system to ensure that the sealing structure is in a positive pressure state, and the wear particles generated in the bearing cannot invade the sealing structure.

The metal surface seal disclosed in the present invention involves two solutions, one is a DF type metal surface contact floating seal using a Belleville washer/diamond cross-section rubber seal ring, and the other is a DO type metal surface floating seal using an O-shaped rubber seal ring. Since the size of the seal used in the wind power device is very large, the DF type metal surface contact seal using a Belleville washer is more preferred.

FIG18 shows an overall view of a bearing unit using a DF type metal face seal, and FIG19 shows a schematic diagram of its hub side seal structure, which corresponds to the area of the left circle in FIG18. Among them, the retaining ring 2502A is fixed to the unit inner cylinder by fixing screws 2501A to achieve axial positioning of the first bearing and the second bearing on the unit inner cylinder to prevent their axial movement. The DF type metal face seal assembly 2607 plays a sealing role, including a sealing seat 2605, a sealing seat 2606, Belle rubber seal rings 2607A and 2607A, metal face seals 2607C and 2607D, etc. Among them, the metal face seals 2607C and 2607D play a sealing role, one rotates, and the other is relatively stationary. Belle rubber seal rings 2607A and 2607B are respectively installed between the metal face seals 2607C, 2607D and the inner cavities of the sealing seats 2605 and 2606. The elastic force of the Belle rubber seal rings 2607A and 2607B makes the two end faces of the metal face seals 2607C and 2607D tightly bonded, and a very thin lubricating oil film is maintained between the end faces to achieve the purpose of sealing. The spacers 2611, 2504 and the baffle 2609 are used to prevent the contaminants in the bearing unit from invading between the metal face seals 2607C and 2607D, causing the sealing surface of the metal face seal to wear and cause the seal to fail.

In Fig. 19, O-ring 2603A is used to prevent lubricating oil from leaking between floating seal seat 2605 and the inner wall of the unit outer cylinder. O-ring 2603B is used to prevent lubricating oil from leaking between floating seal seat 2606 and the unit inner cylinder. Screw 2601 fixes cover plate 2602 to the unit outer cylinder.

In FIG. 19 , the lubricating gas sealing pipeline 2608 is used to lubricate and gas-seal the metal surface sealing structure, and includes a lubricating oil gas inlet 2608A, a pipeline 2608B processed inside the sealing seat 2605 and passing through the cover plate 2602, and a lubricating outlet 2608C for oil and gas lubrication management. The oil and gas entering through the lubricating oil gas inlet 2608A, after passing through the pipeline 2608B and reaching the lubricating outlet 2608C, realize the lubrication of the metal surface seals 2607C and 2607D, and the gas is discharged through the space 2610 between the baffle 2609 and the floating seal seat 2605, and then returns to the oil tank of the lubrication system through the return oil pipe 2604. In order to ensure good lubrication of the metal sealing surface friction pair, it is preferred to evenly distribute multiple lubricating gas sealing pipelines along the circumferential direction of the bearing. Among them, the cover plate 2602 and the sealing seat 2605 can be processed into one piece.

FIG20 shows the sealing structure of the blade side in the bearing unit of FIG18, which corresponds to the area of the right circle in FIG18. Among them, the retaining ring 2502B is fixed on the inner cylinder of the unit by fixing screws 2501B to realize the axial positioning of the first bearing and the second bearing on the inner cylinder of the unit to prevent their axial movement. The DF type metal face seal assembly 2707 plays a sealing role, which includes sealing seats 2705 and 2706, Belle rubber seal rings 2707A and 2707B, metal face seals 2707C and 2707D, etc. Among them, the metal face seals 2707C and 2707D play a sealing role, one rotates and the other is relatively stationary. The Belle rubber seal rings 2707A and 2707B are installed between the metal face seals 2707C and 2707D and the inner cavities of the sealing seats 2705 and 2706. The elastic force of the Belle rubber seal rings 2707A and 2707B makes the two end faces of the metal face seals 2707C and 2707D tightly bonded, and a very thin lubricating oil film is maintained between the end faces to achieve the purpose of sealing. The baffle 2609 prevents pollutants in the bearing unit from invading between the metal face seals 2707C and 2707D, causing the sealing surfaces of the metal face seals 2707C and 2707D to wear and cause sealing failure.

In Fig. 20, O-ring 2703A prevents lubricating oil from leaking between seal seat 2705 and the unit outer cylinder. O-ring 2703B prevents lubricating oil from leaking between seal seat 2706 and the unit inner cylinder of the bearing unit. Screws 2701 fix cover plate 2702 to the unit outer cylinder.

In Figure 20, the lubricating gas sealing pipeline 2708 is used to lubricate and gas-seal the metal face sealing structure, which includes a lubricating oil and gas inlet port 2708A, a pipeline 2708B processed inside the sealing seat 2705 and passing through the cover plate 2702, and a lubricating outlet 2708C for oil and gas lubrication management.

The oil and gas entering through the lubricating oil and gas inlet 2708A, after passing through the pipeline 2708B and reaching the lubrication outlet 2708C, realizes the lubrication of the metal surface seals 2707C and 2707D, and the gas is discharged through the space 2710 between the baffle 2709 and the floating seal seat 2705, and then returns to the oil tank of the lubrication system through the return oil pipe 2704. In order to ensure that the metal sealing surface friction pair is well lubricated, it is preferred to evenly distribute multiple lubricating gas sealing pipelines along the circumferential direction of the bearing. Among them, the cover plate 2702 and the sealing seat 2705 can be processed into one piece.

The cover plate 2602 and the sealing seat 2605 in Figure 19 can be processed into one piece. In addition, the cover plate 2702 and the sealing seat 2705 in Figure 20 can be processed into one piece.

FIG21 shows a solution using a DO type metal face seal. Compared with the sealing solutions of FIG18 to FIG20 , the main difference lies in the form of the sealing ring and the metal face seal, but the structure and principle are the same and will not be repeated in this article.

The metal face sealing scheme proposed in the present disclosure has at least the following advantages: 1. The variable pitch bearing is in a state of trace circulating oil, and the lubrication effect becomes very good. There will be no poor lubrication due to lack of grease or insufficient oil content, which greatly improves the reliability of the variable pitch bearing. 2. The variable pitch bearing is lubricated with trace circulating oil, and measures such as lubricating oil cleaning, water removal, moisture intrusion control, and oil quality status monitoring are set in the circulating oil system, which greatly improves the reliability of the system, the predictability of system failures, and the identifiability of failures. It is better to take precautionary measures in the early stage of variable pitch bearing failure. Reduce the losses caused by failures of the variable pitch system. 3. The metal face seal can ensure that the lubricating oil does not leak during the operation of the variable pitch bearing, and achieve the same performance as the wind turbine.

The exemplary implementation scheme of the present disclosure is described in detail above with reference to the preferred embodiments. However, it can be understood by those skilled in the art that, without departing from the concept of the present disclosure, various modifications and variations can be made to the above-mentioned specific embodiments, and various technical features and structures proposed in the present disclosure can be combined in various ways without exceeding the protection scope of the present disclosure, which is determined by the attached claims.

Claims (10)

1. A bearing unit, characterized by comprising: Unit outer cylinder; A unit inner cylinder, surrounded by the unit outer cylinder; A first bearing and a second bearing, located between the unit outer cylinder and the unit inner cylinder, and spaced apart in the axial direction of the bearing unit; The distance between the first bearing and the second bearing is 10% to 40% of the outer diameter of the first bearing and/or the second bearing. 2. The bearing unit according to claim 1, characterized in that The bearing unit is provided with one or more lubricating oil delivery paths for delivering lubricating oil to the first bearing and/or the second bearing. 3. The bearing unit according to claim 2, characterized in that: Each lubricating oil delivery path includes a lubricating oil delivery passage passing through the unit outer cylinder. 4. The bearing unit according to claim 3, characterized in that: Each lubricating oil delivery path further includes an oil injection piece communicated with the lubricating oil delivery channel, wherein the oil injection piece at least partially extends around the unit inner cylinder and is provided with a plurality of oil injection ports. 5. The bearing unit according to claim 4, characterized in that The oil injection piece is a hollow annular structure surrounding the unit inner cylinder. 6. The bearing unit according to claim 2, characterized in that: The lubricating oil delivery path includes first and second lubricating oil delivery paths for delivering lubricating oil to first and second sides of the first bearing, respectively, and third and fourth lubricating oil delivery paths for delivering lubricating oil to first and second sides of the second bearing, respectively. 7. The bearing unit according to claim 6, characterized in that The second lubricating oil delivery path and the third lubricating oil delivery path share a common lubricating oil delivery passage that passes through the unit outer cylinder. 8. The bearing unit according to claim 1, characterized in that: The bearing unit further includes a compressed air conduit passing through the unit outer cylinder to deliver compressed air to a space between the first bearing and the second bearing. 9. The bearing unit according to claim 1, characterized in that: The inner wall of the unit outer cylinder is provided with a first shoulder and a second shoulder for mounting the first bearing and the second bearing, and the outer wall of the unit inner cylinder is provided with a third shoulder for mounting the second bearing; The bearing unit further includes a positioning ring surrounding the unit inner cylinder at an end of the unit inner cylinder adjacent to the first bearing; The second bearing abuts between the second shoulder and the third shoulder, and the first bearing abuts between the first shoulder and the positioning ring. 10. The bearing unit according to claim 1, characterized in that The bearing unit further includes an inner spacer surrounding the unit inner cylinder, and two ends of the inner spacer respectively abut against the first bearing and the second bearing.