US20160069328A1

US20160069328A1 - Bearing construction for a turbine blade

Info

Publication number: US20160069328A1
Application number: US14/781,660
Authority: US
Inventors: Jascha Van Pommeren; Laurens Verhulst; Koos Welling
Original assignee: SKF AB
Current assignee: SKF AB
Priority date: 2013-04-03
Filing date: 2014-03-28
Publication date: 2016-03-10
Also published as: CN105074204A; WO2014161607A1; WO2014161790A1; CN105264223A; US9938959B2; CN105074204B; US20160053746A1

Abstract

A bearing construction for rotationally supporting a wind turbine blade relative to a wind turbine hub, comprising a dynamic frame connecting the turbine blade and a static frame connecting the turbine hub. The dynamic frame is rotationally supported relative to the static frame by first and second axially spaced bearings. The dynamic and static frames comprise first and second bearing seats for the first and second bearings, respectively, and a first conical section having a cone base and a cone apex, and two or more frame legs circumferential openings in between. The dynamic and static frames are mutually overlapping, wherein the frame legs of one frame pass through openings between the frame legs of the other frame. The first conical sections of the static frame and the dynamic frame are oriented in the same direction, whereby a bearing seat is provided at the cone apex of each first conical section.

Description

CROSS REFERENCE TO RELATED APPLICATION

This is a United States National Stage application claiming the benefit of International Application Number PCT/EP2014/056327 filed on 28 Mar. 2014, which claims the benefit of International Application Number PCT/EP2013/057048 filed on 3 Apr. 2013, both of which are incorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to the field of pitch bearings for enabling a turbine blade to be rotated relative to a turbine hub.

BACKGROUND TO THE INVENTION

Typically, wind turbine blades are connected to the hub using a slewing bearing with a diameter that is approximately equal to the diameter of the blade root. Wind turbines are becoming larger and larger, and the blade root can have a diameter of more than 3 metres. A slewing bearing with an equivalent diameter generates a substantial amount of friction. Also, the slewing bearings experience a high level of wear, due to the relatively small back and forth rotations that the bearing undergoes during operation, especially when individual pitch control is applied, and due to the associated difficulty of maintaining a good lubrication film. Consequently, the use of slewing bearings and other types of rolling element bearings as pitch bearings in wind turbines has disadvantages.
An alternative design for a pitch bearing assembly is disclosed in DE2855992. The assembly comprises two axially spaced bearings which are connected to the blade and hub respectively via two mutually overlapping and oppositely oriented conical structures. The bearings are arranged at the cone apices, the apex of each cone lying in a base plane of the other, and have a diameter that is considerably less than the blade root diameter. This is advantageous in terms of reducing friction.
The mutually overlapping conical structures of this pitch bearing assembly enable a limited amount of relative rotation between the hub and the blade. The conical structures have three spokes, meaning that if the spokes were infinitely thin, a relative rotation of 120 degrees would be possible. However, the spokes need to be sufficiently robust to transmit the high loads that act on the turbine blade. As the spokes become thicker, the angular range of the relative rotation decreases.
Consequently, there is room for improvement in terms of providing a bearing construction comprising mutually overlapping conical structures which possess sufficient strength and enables an optimal range of relative angular rotation.

SUMMARY OF THE INVENTION

The present invention resides in a bearing construction for rotationally supporting a wind turbine blade relative to a wind turbine hub, comprising a dynamic frame configured for connection to the turbine blade and a static frame configured for connection to the turbine hub. The dynamic frame is rotationally supported relative to the static frame by means of first and second axially spaced bearings, whereby each of the dynamic and static frame comprises a first bearing seat for the first bearing and a second bearing seat for the second bearing. Further, each of the dynamic and static frame comprises a first conical section having a cone base and a cone apex, and two or more frame legs with openings in between. The dynamic and static frames are mutually overlapping, such that the frame legs of one frame pass through the openings between the frame legs of the other frame. According to the invention, the first conical section of the static frame and of the dynamic frame are oriented in the same direction, whereby the cone apex of each first conical section is provided with a bearing seat.
As a result of orienting the conical sections in the same direction, a penetration region—where the frame legs of the static and dynamic frames pass through each other—can be arranged at a large-diameter region of the static frame and of the dynamic frame. Consequently, the frame legs may be executed with a thickness that provides the necessary strength, without overly restricting the degree of relative rotation between the static and dynamic frames. In a preferred example, each of the dynamic and static frames has three frame legs arranged at even intervals, whereby approximately 100 degrees of relative rotation is possible.
In a first embodiment of the invention, the static and dynamic frames comprise only a first conical section. The second bearing seat of the dynamic frame and of the static frame is then arranged in a central portion of the cone base of the respective frame. In one example, the second bearing seat of the dynamic frame is arranged in the plane of the cone base of the dynamic frame. The dynamic frame legs then extend in a purely radial direction between the second bearing seat and the cone base of the dynamic frame. The static frame legs connect the cone base of the static frame with the second bearing seat of the static frame and preferably comprise an axial extension and a radial extension. The axial extension of the static frame legs extends from the cone base and passes through the openings between the dynamic frame legs, before extending a radial direction to the second bearing seat. The penetration region can thus be arranged at a large-diameter region of both frames.
In a further example, the second bearing seat of the static frame is arranged in the plane of the cone base of the static frame and has purely radially extending static frame legs. The dynamic frame legs then suitably comprise an axial extension and a radial extension as described above.
In a second embodiment of the invention, one or both of the static and dynamic frames comprises oppositely oriented first and second conical sections, and have an essentially diamond shape. The advantage of a diamond-shaped frame is that the force lines through the frame legs are relatively shorter, enabling less material to be used. This is beneficial in terms of weight reduction.
In one example, both frames comprise first and second conical sections which are connected by a common cone base. The first bearing seat of the static frame and of the dynamic frame is arranged at the cone apex of the corresponding first conical section, and the second bearing seat of the static frame and of the dynamic frame is arranged at the cone apex of the corresponding second conical section. Suitably, the frame legs of at least one of the dynamic and static frames form part of a conical section of that frame.
The first bearing seat of the static frame and of the dynamic frame will be designated as the bearing seat for a hub-side bearing of the bearing construction. Likewise, the second bearing seat of the static frame and of the dynamic frame will be designated as the bearing seat for a blade-side bearing of the bearing construction.
It should be noted that the hub-side bearing seat of the static frame can be a shaft element for receiving an inner ring of the hub-side bearing or can be a housing element for receiving an outer ring of the hub-side bearing. Likewise, the blade-side bearing seat of the static frame can be a shaft element for receiving an inner ring of the hub-side bearing or can be a housing element for receiving an outer ring of the blade-side bearing. Similarly, the hub-side bearing seat of the dynamic frame can be a shaft element for receiving the inner ring of the hub-side bearing or can be a housing element for receiving the outer ring of the hub-side bearing, and the blade-side bearing seat of the dynamic frame can be a shaft element for receiving the inner ring of the blade-side bearing or can be a housing element for receiving the outer ring of the blade-side bearing.
When the hub-side and blade-side bearing seats of one the frames is formed by a shaft element, the seats may be provided on axially spaced portions of the same shaft section. Alternatively, the frame in question may comprise two short shaft sections. It is also possible for the hub-side bearing seat of a frame to be configured for connection to e.g. the outer ring of the hub-side bearing while the blade-side seat of the same frame is configured for connection to the inner ring of the blade-side bearing.
Preferably, the blade-side bearing and the hub-side bearing comprises a radial spherical plain bearing. This type of bearing has advantageous properties in terms of wear resistance, which is important in pitch bearing applications where the majority of rotational movements are small back-and-forth oscillations.
The static frame of the bearing construction is mounted to the hub. In some examples, the static frame comprises a cylindrical hub interface for connection to the hub. The hub interface suitably comprises a cylindrical connection portion that is joined to the cone base of the static frame by the static frame legs. The dynamic frame legs may form part of a conical section that connects the cone base of the dynamic frame to the bearing seat of the hub-side bearing.
In other examples, the cone base of the static frame is mounted to the hub. The dynamic frame may then further comprise a cylindrical blade interface to which the turbine blade is connected. The blade interface suitably comprises a cylindrical connection portion that is joined to the cone base of the dynamic frame by the dynamic frame legs. The static frame legs may form part of a conical section that connects the cone base of the static frame to the bearing seat for the blade-side bearing.
When the cone base of the static frame is connected to the turbine hub, the bearing seat for the hub-side bearing may be arranged in a central region of the hub, close to an axis of the turbine main shaft. Such an arrangement is advantageous in terms of compactness. In a further development of the invention, two or more bearing constructions are arranged radially around the main shaft axis of the turbine and the arrangement further comprises a central shaft section. The central shaft section is connectable to the turbine main shaft and interconnects the hub-side bearing seat of the static frame of each bearing construction. Preferably, the cone bases of each static frame are connected to each other and are connected to the central shaft portion at a front side and at a rear side of the central shaft portion. The interconnection of the static frames at the heart of the hub improves the strength and load-transfer capabilities of the construction as a whole.
These and other advantages will become apparent from the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described further, with reference to the following Figures, in which:

FIG. 1 a, FIG. 1 b respectively show a perspective view and a cross-sectional view of a first example of a bearing construction according to the invention;

FIG. 2 shows a perspective view of a second example of a bearing construction according to the invention, mounted to a turbine hub;

FIG. 3 shows a cross-sectional view of an arrangement of three bearing constructions according to the invention;

FIG. 4 shows a cross-section view of a further arrangement of three bearing constructions according to the invention; and

FIG. 5 shows an example of a wind turbine.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

FIG. 5 is a front view of a wind turbine 5 comprising three blades 10 connected to a hub 20. The hub is connected via a main shaft (not shown) to a generator, arranged in a nacelle 30 mounted on a tower 40. To maximize the amount of energy captured by the blades while minimizing the load on the blades, the wind turbine is equipped with an individual pitch control system. Each blade 10 is rotatable relative to the hub 20 about a blade pitch axis, and is rotationally supported by a bearing construction.
In order to minimize friction, a bearing construction according to the invention comprises axially spaced first and second bearings, which have a diameter that is significantly smaller than a blade root diameter of the turbine blade. The bearing construction further comprises mutually overlapping frames which connect the first and second bearings to each other. The frames must therefore be sufficiently robust to transmit the high application loads on the blade to the hub.
A first embodiment of a bearing construction according to the invention is shown in a perspective view and in a cross-sectional view in FIG. 1 a and FIG. 1 b. The bearing construction 100 comprises a dynamic frame 110 and a static frame 130, which are rotationally supported relative to each other by means of first and second bearings 150, 160.
In use of the bearing construction, a wind turbine blade is mounted to the dynamic frame 110 and the static frame 130 is mounted to the wind turbine hub, which is in connection with the turbine main shaft. The dynamic frame 110 comprises a cylindrical section to which the turbine blade is mounted and further comprises a conical section. The conical section has a large-diameter cone base 113 and a small-diameter cone apex 115 which are connected via frame bars 117. The conical section of the dynamic frame 110 extends along the blade pitch axis, inside of the cylindrical section.
The static frame also comprises a conical section with a large-diameter cone base 133 and a small-diameter cone apex 135 joined by frame bars 137. The conical sections of both frames are oriented in the same direction, such that the cone apex 115 of the dynamic frame lies at the cone apex 135 of the static frame.
To enable a pitch angle of the turbine blade to be adjusted about the blade pitch axis, the dynamic frame 110 is rotationally supported relative to the static frame by means of a hub-side bearing 150 and a blade-side bearing 160, axially spaced from the hub-side bearing.
Thus, the dynamic frame 110 has a hub-side bearing seat 120 and a blade-side bearing seat 125 for the hub- and blade- side bearings 150, 160 respectively, and the static frame 130 has a hub-side bearing seat 140 and a blade-side bearing seat 145 for the hub- and blade- side bearings 150, 160 respectively.
The blade-side bearing seat 125 of the dynamic frame is provided at the cone apex 115 and forms a housing part to which an outer ring of the blade-side bearing 160 is mounted. The blade-side bearing seat 145 of the static frame is provided at the static frame cone apex 135 and is formed by a shaft part that serves as an inner ring of the blade-side bearing 160.
In the depicted example, the hub-side bearing seat 120 of the dynamic frame is located at a centre region of the of the cone base 113, and forms a housing part to which an outer ring of the hub-side bearing 150 is mounted. The outer ring can be mounted directly to the bearing seat 120 or, as shown in the example of FIG. 1 b, can be indirectly mounted to the bearing seat via a conical sleeve. The hub-side bearing seat 120 lies in the plane of the cone base 113 of the dynamic frame and is joined to the cone base 113 by three evenly spaced dynamic frame legs 122, which extend in a radial direction. The hub-side bearing seat 140 of the static frame is likewise located at a central region of the static frame cone base 133, and forms a shaft part to which an inner ring of the hub-side bearing 150 is mounted. The shaft part 140 is joined to the cone base 133 of the static frame by three evenly spaced static frame legs 142 which penetrate through openings between the legs 122 of the dynamic frame. The cone base 133 of the static frame lies axially closer to a hub-side 180 of the bearing construction than the cone base 113 of the dynamic frame, and the static frame legs 142 extend in an axial direction through the openings between the dynamic frame legs, then extend radially inwards to the hub-side bearing seat 140 (shaft part) of the static frame.
The maximum relative angular displacement between the static and dynamic frames is dependent on the thickness of the frame legs 122, 142 and on the circumference of a penetration region where the legs pass through each other. In the depicted example, the region of penetration is arranged at the cone base 113 of the dynamic frame and close to the cone base 133 of the static frame. In other words, the penetration region is arranged at a large-diameter part of both frames, meaning that the frame legs can be made sufficiently thick to withstand high loads, while retaining an acceptable range of relative angular rotation of around 100 degrees.
An example of a second embodiment of a bearing construction according to the invention is depicted in FIG. 2. The bearing construction 200 is mounted to the hub 205 of a wind turbine. and comprises a dynamic frame with a first conical section 211 and a second conical section 212 that is oppositely oriented from the first conical section. A common cone base 213 connects the first and second conical sections 211, 222. The dynamic frame is thus essentially diamond shaped.
The first conical section has a cone apex, where a bearing seat for a hub-side bearing (not visible) is provided. The dynamic frame further comprises three evenly spaced frame legs 222 with openings in between. The dynamic frame legs 222 form part of the first conical section 211 and connect the cone apex of the first conical section to the cone base 213. The second conical section 212 has a cone apex 215 with a bearing seat for a blade-side bearing (not visible). In the depicted example, the second conical section is formed by a solid cone. A frame or truss configuration is also possible.
The static frame is also essentially diamond shaped and comprises oppositely oriented first and second conical sections which are connected via a cone base 233. At a cone apex (not visible) of the first conical section 231, a bearing seat for the hub-side bearing (not visible) is provided. The static frame further comprises a cylindrical hub interface 234 that is mounted to the hub 205. The hub interface 234 comprises three static frame legs 242, which are evenly spaced around the circumference and which are connected to the cone base 233 of the static frame. The static frame legs 242 have openings in between, though which the dynamic frame legs 222 penetrate. In accordance with the invention, the penetration region is provided close to the cone bases 213, 233 of the static and dynamic frames, which again optimizes the range of relative angular displacement for the leg thickness that is required in order to transmit the high loads.
The second conical section of the static frame (not visible) extends inside the second conical section 212 of the dynamic frame, and has a cone apex where a bearing seat is provided for the blade-side bearing. The second conical section may be a solid cone or may be formed from a frame or truss configuration.
An advantage of a diamond configuration of the static and dynamic frames is that the force lines through the frames are relatively short, meaning that less material is needed. A robust construction of lower weight can thus be achieved.
In the second embodiment of the invention (diamond configuration) the hub-side bearing is arranged at the cone apex of two conical sections. The first embodiment of the invention, where the static and dynamic frames each comprise only one conical section, can also be executed such that the hub-side bearing is located at the cone apices. An advantage of doing this is that the hub-side bearing can be arranged closer to a rotation axis of the turbine main shaft. This can be seen in FIG. 3, which shows an arrangement of three bearing constructions according to a further example of the second embodiment of the invention. NB: For clarity reasons, not all of the features common to each have been provided with reference numerals
The dynamic frame of each bearing construction has a first conical section 311 and an oppositely oriented second conical section 312, which are connected by a cone base 313. The dynamic frame further comprises a central shaft section 318 with axially spaced bearing seats 320, 325 for a hub-side bearing 350 and a blade-side bearing 360. The first and second conical sections 311, 312 are connected to the bearing seats on the shaft section 318 at an apex region of each conical section.
The static frame of each bearing construction has a first conical section 331 and an oppositely oriented second conical section 332, which are connected by a cone base 333. The cone base 333 is mounted to the hub 305 and lies radially outside of the cone base 313 of the dynamic frame. Thus, the first conical section 311, 331 of each frame extends towards a centre region of the hub 305, where the turbine main shaft (not shown) is located. An assembly of bearing constructions according to the depicted embodiment is thus compact.
Further, the static frame of each bearing construction has a first bearing seat 340 for the hub-side bearing 350 and a second bearing seat 345 for the blade-side bearing 360. As before, the first and second bearing seats of each frame are arranged at a cone apex of the respective conical section.
In this example, the first and second conical sections 311, 312 of the dynamic frame are arranged inside the first and second conical sections 331, 332 of the static frame respectively. The dynamic frame further comprises a blade-mounting interface 314 and has three dynamic frame legs 322 that connect blade-mounting interface 314 to the cone base 313 of the dynamic frame. The static frame has three static frame legs 342 that connect the cone base 333 of the static frame to the second bearing seat 345. The static frame legs 342 form part of the second conical section of the static frame. As before, the static frame legs penetrate through the openings between the dynamic frame legs 322 in a large-diameter region of each frame, at the respective cone base 313, 333.
As mentioned, the hub and bearing construction becomes more compact when the hub-side bearing 350 is arranged in a central region of the hub. To provide the construction as whole with additional robustness, it is advantageous if the first bearing seats 340 of each static frame are interconnected. The first bearing seats may be formed by shaft sections that extend in a radial direction from a central shaft, whereby the central shaft is connected to the turbine main shaft. In the example of FIG. 3, the first bearing seats 340 are formed by a bore for receiving the outer ring of the hub-side bearing 340. The shaft sections would then be hollow shaft sections.
In an alternative example, as depicted in the assembly FIG. 4, the first bearing seat of the static frames is a shaft section to which the inner ring of the hub-side bearing is mounted.
The assembly comprises three bearing constructions according to the invention, whereby the static frames of the constructions are interconnected to form an integrated hub and bearing assembly.
Each bearing construction has a dynamic frame comprising a first conical section 411 and an oppositely oriented second conical section 412 that extends from a cylindrical cone base 413. A bearing seat 420, 425 for the hub-side bearing and the blade-side bearing are provided at the apex 415 of each conical section. Further, each dynamic frame has three dynamic frame legs 422 with openings in between, arranged at even intervals around a cylindrical cone base 413. In this example, the dynamic frame legs extend in an essentially axial direction and form part of the cone base 413 that interconnects the first and second conical sections.
The static frame of each bearing construction comprises a conical section 431, whereby a bearing seat 445 for the blade-side bearing is provided at an apex 435 of the conical section. A cone base 433 of each static conical section 431 is connected to the cone base of an adjacent section. Further, each static frame has three evenly spaced static frame legs 442 which extend from the cone base 433 to the cone apex 435 and pass through the openings between the dynamic frame legs 422. Again, the legs penetrate through each other in a large-diameter region of each frame, meaning that the legs can be sufficiently thick and strong for supporting the high loads from the turbine blade, while enabling a sufficient degree of relative rotation.
The assembly further comprises a central shaft 470, which extends along an axis of the turbine main shaft. Extending in a radial direction, the central shaft 470 has three shaft sections which form the hub-side bearing seat 440 of the static frame of each bearing construction. Suitably, the cone base 433 of each static frame is also structurally connected to the central shaft 470 at a front side of the hub 405 and at a rear side of the hub. This interconnection of the static frames at the heart of the hub and bearing assembly couples the static frames firmly together, which significantly increases the strength and stiffness of the overall assembly. Furthermore, the loads on the hub-side bearing are transmitted to the hub at the central shaft 470, enabling a more direct transfer of those loads to the turbine main shaft in comparison with conventional wind turbine hubs.
A number of aspects/embodiments of the invention have been described. It is to be understood that each aspect/embodiment may be combined with any other aspect/embodiment. Moreover the invention is not restricted to the described embodiments, but may be varied within the scope of the accompanying patent claims.

REFERENCE NUMERALS

5 Wind turbine
10 Turbine blade
20 Turbine hub
30 Nacelle
40 Tower
100 Bearing construction
110 Dynamic frame
113 Cone base of conical section of dynamic frame
115 Cone apex of conical section of dynamic frame
117 Frame bars of conical section of dynamic frame
120 First bearing seat of dynamic frame
122 Dynamic frame leg
125 Second bearing seat of dynamic frame
130 Static frame
133 Cone base of conical section of static frame
135 Cone apex of conical section of static frame
137 Frame bars of conical section of static frame
140 First bearing seat of static frame
142 Static frame leg
145 Second bearing seat of static frame
150 First bearing
160 Second bearing
180 Hub-side of bearing construction
200 Bearing construction
205 Hub of wind turbine
211 First conical section of dynamic frame
212 Second conical section of dynamic frame
213 Cone base of conical sections of dynamic frame
215 Cone apex of conical sections of dynamic frame
222 Dynamic frame leg
231 First conical section of static frame
233 Cone base of conical section of dynamic frame
234 cylindrical hub interface of static frame
242 Static frame leg
305 Hub of wind turbine
311 First conical section of dynamic frame
312 Second conical section of dynamic frame
313 Cone base of conical sections of dynamic frame
314 Cylindrical blade interface of dynamic frame
315 Cone apex of conical sections of dynamic frame
318 Shaft section of dynamic frame
320 Hub-side bearing seat of dynamic frame
322 Dynamic frame leg
325 Blade-side bearing seat of dynamic frame
331 First conical section of static frame
332 Second conical section of static frame
333 Cone base of conical section of dynamic frame
340 Hub-side bearing seat of static frame
342 Static frame leg
345 Blade-side bearing seat of static frame
350 Hub-side bearing
360 Blade-side bearing
411 First conical section of dynamic frame
412 Second conical section of dynamic frame
413 Cone base of conical sections of dynamic frame
415 Cone apex of conical sections of dynamic frame
420 Hub-side bearing seat of dynamic frame
422 Dynamic frame leg
425 Blade-side bearing seat of dynamic frame
431 First conical section of static frame
433 Cone base of conical section of dynamic frame
440 Hub-side bearing seat of static frame
442 Static frame leg
445 Blade-side bearing seat of static frame
470 Central shaft portion on which first bearing seat of each static frame is provided

Claims

1. A bearing construction for rotationally supporting a turbine blade relative to a turbine hub, comprising:

a dynamic frame configured for connection to the turbine blade;

a static frame configured for connection to the turbine hub; and

a first axially spaced bearing and a second axially spaced bearing adapted to rotationally support the dynamic frame relative to the static frame,

wherein each of the dynamic and static frame comprises:

a first bearing seat for the first axially spaced bearing and a second bearing seat for the second axially spaced bearing;

a first conical section having a cone base and a cone apex; and

at least two frame legs with openings in between;

wherein the dynamic and static frames are mutually overlapping, such that the frame legs of one frame pass through the openings between the frame legs of the other frame,

wherein the first conical section of the static frame and the first conical section of the dynamic frame are oriented in the same direction,

wherein the cone apex of each first conical section is provided with a bearing seat.

2. The bearing construction according to claim 1, wherein the frame legs pass through each other at a large-diameter region of the static frame and of the dynamic frame, close to or at the cone base of each conical section.

3. The bearing construction according to claim 1, wherein the cone apex of each first conical section is arranged at a hub side of the construction and comprises a hub-side bearing seat.

4. The bearing construction according to claim 3, wherein the hub-side bearing seat of the static frame is arranged in a central region of the hub, close to a rotation axis of the turbine main shaft.

5. The bearing construction according to claim 4, wherein the hub-side bearing seat is connected to the hub-side bearing seat of a further static frame, the connection comprising a central shaft portion that is configured for mounting to the turbine main shaft.

6. The bearing construction according to claim 1, wherein each of the static frame and the dynamic frame comprises only a first conical section, and

a bearing seat arrangement being one of:

wherein a bearing seat of the dynamic frame is arranged in a plane of the cone base of the dynamic frame, or

wherein a bearing seat of the static frame is arranged in a plane of the cone base of the static frame.

7. The bearing construction according to claim 6, wherein the frame legs of the frame which has its bearing seat in the plane of the cone base, extend in a purely radial direction.

8. The bearing construction according to claim 1, wherein at least one of the static and dynamic frames further comprises:

a second conical section oppositely oriented from the first conical section,

whereby a cone apex of the second conical section is provided with a bearing seat.

9. The bearing construction according to claim 8, wherein the frame legs of the at least one frame form part of a conical section of that frame.

10. The bearing construction according to claim 8, wherein the dynamic frame further comprises a cylindrical blade interface that extends from the cone base of the first conical section, and

wherein the dynamic frame legs form part of the cylindrical blade interface.

11. The bearing construction according to claim 1, wherein the cone base of the first conical section of the static frame is configured for mounting to the hub.

12. The bearing construction according to claim 8, wherein the static frame further comprises a cylindrical hub interface, configured for mounting to the hub, and

wherein the static frame legs form part of the cylindrical hub interface and extend from the cone base of the static frame.

13. The bearing construction according to claim 1, wherein one or both of the first bearing and the second bearing comprises a radial spherical plain bearing.

14. The bearing construction according to claim 1, wherein the first bearing seat and the second bearing seat of the static frame are configured for receiving one of a bearing inner ring or a bearing outer ring.

15. The bearing construction according to claim 1, wherein the first bearing seat and the second bearing seat of the dynamic frame are configured for receiving one of a bearing inner ring or a bearing outer ring.

16. The bearing construction according to claim 1, wherein the first bearing seat of one of the dynamic frame or the static frame is configured to receive a bearing inner ring and the second bearing seat of the one of the dynamic frame or the static frame is configured to receive a bearing outer ring.