Bearing element

A bearing element has at least one inner ring element and at least one outer ring element, wherein, between the inner ring element and the outer ring element, a sliding bearing system is disposed that is formed by at least two sliding bearings. The sliding bearings have a sliding face, which cooperates with a running face of the opposite ring element. In the new condition of the sliding bearing, the sliding face of the sliding bearing, viewed in cross section, has at least one first sub-portion and one second sub-portion, wherein a tangent constructed on the first sub-portion is disposed at a first angle relative to the central longitudinal axis and a tangent constructed on the second sub-portion is disposed at a second angle relative to the central longitudinal axis, wherein the first angle has a magnitude different from that of the second angle.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Stage of PCT/AT2017/060273 filed on Oct. 19, 2017, which claims priority under 35 U.S.C. § 119 of Austrian Application No. A 50969/2016 filed on Oct. 21, 2016, the disclosure of which is incorporated by reference. The international application under PCT article 21(2) was not published in English.

The invention relates to a bearing element for the bearing system of a structural part.

From AT 509 625 B1, a bearing element is known for the bearing system of the rotor hub of a wind turbine. The bearing element comprises an outer ring, an inner ring and several sliding-bearing pads, which are disposed between the outer ring and the inner ring. The bearing element is designed for a radial or an axial force load and is able to absorb a superposed tilting torque to only limited extent.

The task of the present invention was to overcome the disadvantages of the prior art and to provide a bearing element by means of which a structural part loaded with a radial force, an axial force and a tilting torque can be mounted.

This task is accomplished by a device according to the claims.

According to the invention, a bearing element, especially a rotor-hub bearing system, is designed for the bearing system of a structural part to be loaded with a radial force, an axial force and a tilting torque. The bearing element comprises at least one inner ring element and at least one outer ring element, which in the unloaded condition are disposed coaxially with one another with respect to a central longitudinal axis, wherein, between the inner ring element and the outer ring element, a sliding-bearing system is disposed that is formed by at least two sliding bearings disposed at an axial spacing relative to one another. The sliding bearings are coupled on a receiving side with one of the ring elements and a sliding face, which cooperates with a running face of the opposite ring element, is formed opposite the receiving side. In the new condition of the sliding bearing, the sliding face of the sliding bearing, viewed in cross section, has at least one first sub-portion and one second sub-portion, wherein a tangent constructed on the first sub-portion is disposed at a first angle relative to the central longitudinal axis and a tangent constructed on the second sub-portion is disposed at a second angle relative to the central longitudinal axis, wherein the first angle has a magnitude different from that of the second angle.

For the construction of the bearing element according to the invention, it is of advantage that the first sub-portion may be designed in such a way that an axial force or a radial force acting on the bearing element can be effectively absorbed and that the second sub-portion may be designed in such a way that a tilting torque acting on the bearing element may be effectively absorbed. Due to the bearing element according to the invention—in contrast to conventional sliding bearings—a point load does not occur during a tilting of the inner ring element relative to the outer ring element, but instead at least a linear contact of the sliding face on the running face can be achieved even during a tilting of the inner ring element relative to the outer ring element. Thereby the surface pressure can be minimized compared with conventional bearing elements, whereby the wear on the bearing elements can also be minimized.

Furthermore, it may be expedient when a tangent, which is constructed on the running face of the ring element cooperating with the sliding bearing, is disposed at a third angle relative to the central longitudinal axis, wherein, in the unloaded condition, the third angle of the running face has the same magnitude as the first angle of the first sub-portion of the sliding face. It is then of advantage that a linear contact can be formed by this feature in a bearing element that is loaded with a radial force or axial force but that does not have any tilting between inner ring element and outer ring element and is not loaded with tilting torques.

Furthermore, it may be provided that the sliding bearing is coupled with the outer ring element and the sliding face is formed on the inner side of the sliding bearing and the running face is formed on the outer side of the inner ring element. Such a construction of the bearing element is advantageous when the outer ring element is designed as a rotating structural part and the inner ring element is constructed as a stationary structural part, since this leads to a reduced wear on the bearing element.

In an alternative embodiment variant, it may be provided that the sliding bearing is coupled with the inner ring element and the sliding face is formed on the outer side of the sliding bearing and the running face is formed on the inner side of the outer ring element. Such a construction of the bearing element is advantageous when the inner ring element is designed as a rotating structural part and the outer ring element is constructed as a stationary structural part, since this leads to a reduced wear on the bearing element.

Beyond this, it may be provided that at least one of the sliding bearings is formed by sliding-bearing pads disposed in distributed manner in circumferential direction. It is then of advantage that such sliding-bearing pads can be easily replaced or taken out in the maintenance situation, without the need to strip the complete bearing element in the process.

A manifestation is also advantageous according to which it may be provided that, in a sliding bearing having a sliding face disposed on the inner side, the first angle of the tangent constructed on the first sub-portion is smaller relative to the central longitudinal axis than the second angle of the tangent constructed on the second sub-portion relative to the central longitudinal axis, and that, in a sliding bearing having a sliding face disposed on the outer side, the first angle of the tangent constructed on the first sub-portion is larger relative to the central longitudinal axis than the second angle of the tangent constructed on the second sub-portion relative to the central longitudinal axis.

According to a further development, it is possible that, in a bearing element loaded by a radial force or an axial force, the running face of the ring element bears on the first sub-portion of the sliding face of the sliding bearing, especially along a first contact line, and the ring element and the sliding bearing can be twisted relative to one another around the central longitudinal axis, and that, in a bearing element loaded by a tilting torque, the running face of the ring element bears on the second sub-portion of the sliding face of the sliding bearing, especially along a second contact line, and the ring element and the sliding bearing can be twisted relative to one another around the central longitudinal axis. It is then of advantage that each of the two sub-portions are designed for load absorption in a special loading condition and thereby the possible useful life of the bearing element can be prolonged.

Furthermore, it may be expedient when the tangent of the second sub-portion is constructed in such a way or has such an angle that, in the unloaded condition of the bearing element, the tangent of the running face is turned around the center of the bearing element in a manner coinciding with the tangent of the second sub-portion. It is then of advantage that, during a loading of the bearing element with a tilting torque, and therefore in the tilted condition of the outer ring element relative to the inner ring element, the running face and the sliding face lie on one another along a second contact line.

Beyond this, it may be provided that the first sub-portion and the second sub-portion, viewed in cross section, are formed by straight lines, which are joined to one another by a transition radius. It is then of advantage that, viewed in cross section, the sub-portions formed by straight lines may cooperate with corresponding mating faces, likewise formed as straight lines when viewed in cross section, and in the process a linear contact is established. The transition radius is preferably chosen to be as small as possible. Preferably, the transition radius may be approximately zero and therefore the straight lines directly intersect one another and form an apex.

Furthermore, it may be provided that an opening angle between the tangent constructed on the first sub-portion and the tangent constructed on the second sub-portion amounts to between 175° and 179.99°, especially between 178° and 179.99°, preferably between 179° and 179.99°. It is then of advantage that, by realization of such an opening angle, correspondingly small bearing clearances can be achieved.

Furthermore, it may be provided that a wind turbine having a rotor hub and a gondola is formed, wherein the rotor hub is mounted on the gondola by means of the described bearing element.

A tangent may be constructed both on a convex curve, such as a circle, for example, as well as on a straight line. In the special case of a straight line, the tangent on the straight line lies on the straight line over the entire length.

The bearing element has the geometric construction in the new condition. This is of advantage in particular, since thereby an excessive wear of the sliding bearing is avoided as much as possible.

By way of introduction, it is pointed out that like parts in the differently described embodiments are denoted with like reference symbols or like structural-part designations, wherein the disclosures contained in the entire description can be carried over logically to like parts with like reference symbols or like structural-part designations. The position indications chosen in the description, such as top, bottom, side, etc., for example, are also relative to the figure being directly described as well as illustrated, and these position indications are to be logically carried over to the new position upon a position change.

FIG. 1shows a schematic diagram of a wind turbine1for generation of electrical energy from wind energy. The wind turbine1comprises a gondola2, which is received rotatably on a tower3. The electrotechnical components such as, for example, generator of the wind turbine1are disposed in the gondola2.

Furthermore, a rotor4is formed, which has a rotor hub5having rotor blades6disposed thereon. In particular, it is provided that the rotor hub5is received by means of a bearing element7in pivotably movable manner on the gondola2.

It is of particular advantage when the bearing element7is designed in conformity with the descriptions provided in this document, since, especially during use of only one bearing element7for the bearing system of the rotor hub5on the gondola2, both a radial force8and an axial force9as well as a tilting torque10must be absorbed by the bearing element7. The axial force9is created by the force of the wind. The radial force8corresponds to the weight force of the rotor4and it acts at the center of gravity of the rotor4. Since the center of gravity of the rotor4is located outside the bearing element7, the tilting torque10in the bearing element7is caused by the radial force8. The tilting torque10may likewise be caused by an uneven load of the rotor blades6.

Alternatively to the use of the bearing element7in a wind turbine1, it is also conceivable that a bearing element7designed in such a way is used, for example, on a slewing ring of an excavator or on another application where both a radial force8and/or an axial force9as well as a tilting torque10act on the bearing element7.

The bearing elements7according to the invention may have, for example, a diameter between 0.5 m and 5 m. Naturally, it is also conceivable that the bearing elements7are smaller or larger.

InFIG. 2, a first exemplary embodiment of the bearing element7is illustrated in an unloaded condition. InFIG. 3, the first exemplary embodiment of the bearing element7fromFIG. 2is illustrated in a condition loaded with a tilting torque10, wherein, once again, like reference symbols or structural-part designations are used for like parts, as in the foregoingFIG. 2. In order to avoid unnecessary repetitions, the bearing element7will be described on the basis of an integrated view ofFIGS. 2 and 3.

The bearing element7comprises at least one inner ring element11, which has an inner side12and an outer side13. Furthermore, an outer ring element14is provided, which has an inner side15and an outer side16. Moreover, a sliding bearing system17, which comprises at least first and second sliding bearings19,19aspaced apart from one another at an axial spacing18, is formed between the inner ring element11and the outer ring element14. The two sliding bearings19,19arespectively have an inner side20and an outer side21.

In the diagram ofFIG. 2, the bearing element7is illustrated in an unloaded condition. An unloaded condition is defined here as that condition in which no forces, and therefore not even any forces of gravity act on the bearing element7. This condition is fictional and will therefore be presented merely for illustration of the structural parts and the function of the bearing element7. As is evident fromFIG. 2, in the unloaded condition of the bearing element7, the inner ring element11and the outer ring element14and the sliding bearing19are disposed concentrically with respect to a common central longitudinal axis22.

In the first exemplary embodiment of the bearing element7, as is illustrated inFIGS. 2 to 6, the sliding bearings19,19aare coupled with the outer ring element14. In the present exemplary embodiment, the side of the sliding bearing19that is coupled with the outer ring element14is referred to as the outer side23of the sliding bearing. On the receiving side23of the sliding bearing19, no relative movement takes place between the sliding bearing19and the outer ring element14. Such a coupling of the sliding bearing19with the outer ring element14may be achieved, for example, by features such as have already been described in AT 509 625 BI.

Furthermore, it is also conceivable that the sliding bearing19is received in the outer ring element14by means of, for example, an adhesive joint. In yet another exemplary embodiment, it is also possible that the sliding bearing19is received interlockingly, for example, in the outer ring element14.

In this case, the sliding bearing19may be subdivided into several ring segments distributed over the circumference. Furthermore, it is also conceivable that the sliding bearing19is designed as an individual circumferential ring. Such a circumferential ring may be inserted, for example, into the outer ring element14, wherein, due to a frictional joint, an induced rotation of the sliding bearing19relative to the outer ring element14is suppressed.

Opposite each receiving side23of the first and second sliding bearing19,19a, a sliding face24,24ais formed, which cooperates with a running face25,25aof the inner ring element11,11a. In the first exemplary embodiment, the outer side13of the inner ring element11,11a, respectively, is designed as the running face25,25a.

In the first exemplary embodiment in particular, it is provided that the sliding bearing19is twisted relative to the inner ring element11, and a sliding movement between the sliding face24of the sliding bearing19and the running face25of the inner ring element11is permitted. Thereby the function of the bearing element7can be realized. The exact function or the exact relationships of the bearing element7are shown in detail inFIGS. 4 to 6, or these diagrams serve as a supplement to the understanding of the first exemplary embodiment of the bearing element7.

Between the inner ring element11and the sliding bearing19, a bearing clearance26is formed, as illustrated inFIG. 2.

At this place, it must be mentioned that the bearing clearance26is illustrated in exaggerated size for clarity, not only inFIGS. 2 and 3but also inFIGS. 4 to 6as well as7to9. Especially inFIGS. 4 to 6as well as7to9, the geometry of the sliding-bearing system is illustrated in greatly exaggerated manner, in order to be able to illustrate the function and the technical effects clearly.

As is evident fromFIG. 2, it may be provided that two inner ring elements11,11aare formed, which are disposed at a spacing27relative to one another. The outer sides13of the first and second inner ring elements11,11aare respectively conically designed and turned toward one another. Due to the spacing27of the two inner ring elements11,11arelative to one another, the bearing clearance26may be adjusted.

The running face25is a face that is designed to be rotationally symmetric with respect to the central longitudinal axis22and that may have the special shape of a truncated cone. Viewed in the cross section of the bearing element7, as illustrated inFIG. 2, the running face25forms a straight line. If a tangent28is constructed on the running face25, this tangent28is formed at an angle29with respect to the central longitudinal axis22.

As is evident fromFIG. 2, and particularly clearly in the exaggerated illustration according toFIG. 4, it is provided that the first sliding bearing19has a first sub-portion30and a second sub-portion31on its first sliding face24. As is also evident fromFIG. 2, it is provided that the second sliding bearing19ahas a third sub-portion30aand a fourth sub-portion31aon its second sliding face24a.

A first tangent32constructed on the first sub-portion30is disposed at a first angle33relative to the central longitudinal axis22. A second tangent34constructed on the second sub-portion31is disposed at a second angle35relative to the central longitudinal axis22. A third tangent32aconstructed on the third sub-portion30,30ais disposed at a third angle33arelative to the central longitudinal axis22. A fourth tangent34aconstructed on the fourth sub-portion31ais disposed at a fourth angle35arelative to the central longitudinal axis22.

In particular, it is provided that the second angle35of the second sub-portion31of the first sliding bearing19and the first angle33of the first sub-portion30have different magnitudes, and the fourth angle35aof the fourth sub-portion31aand the third angle33aof the third sub-portion30ahave different magnitudes. Furthermore, it is provided that the angle29,29aof the running face25,25aand the angle33,33aof the first sub-portion30and third sub-portion30a, respectively, have the same magnitudes and thus, in the unloaded condition of the bearing element7, the tangent28,28aof the running face25,25a, respectively, and the tangent32,32aof the first sub-portion30and third sub-portion30a, respectively, are situated parallel to one another. Considered in the three-dimensional representation, the running face25,25aand the first sub-portion30and third sub-portion30a, respectively, therefore have a shell surface of a truncated cone with the same opening angle.

When the bearing element7, as illustrated inFIG. 5, is loaded with an axial force9and/or a radial force8, the first sub-portion30of the sliding face24of the sliding bearing19and the running face25of the inner ring element11come to bear on one another along a first contact line36. The sliding face24of the sliding bearing19and the running face25of the inner ring element11therefore contact one another along the first contact line36, since the radial force8or the axial force9cause a parallel shift of the two structural parts relative to one another. The parallel shift naturally varies in the range of hundredths to tenths of one millimeter, and is illustrated in greatly exaggerated manner.

However, if a tilting torque10is transmitted into the bearing element7according to the diagram inFIGS. 3 and 6, a tilting of the outer ring element14relative to the inner ring element11takes place, whereby the second sub-portion31of the sliding face24of the sliding bearing19bears on the running face25of the inner ring element11along a second contact line37.

As is evident fromFIG. 3, the two sliding bearings19,19athen lie on the first and second inner ring elements11,11ain diagonally opposite manner. During this described tilting, a twisting of the outer ring element14relative to the inner ring11occurs in particular with respect to a fulcrum38, which is located at the point of intersection between the central longitudinal axis22and a longitudinal middle axis39.

Naturally it is ideal when, after the said tilting of the outer ring element14, the tangent28of the running face25and the tangent34of the second sub-portion31of the sliding face24of the sliding bearing19are situated coincidingly on one another. Thereby, even during a loading of the bearing element7by a tilting torque10, a linear contact therefore takes place between the sliding face24and the running face25, whereby the surface pressure and thus the wear on the sliding face24may be reduced.

The coincidence of the tangent34of the second sub-portion31and of the tangent28of the running face25after the tilting can be achieved in that, during the construction of the sliding bearing19in the unloaded condition corresponding toFIG. 2, the tangent28on the running face25is taken and twisted by a certain angle with respect to the fulcrum38, so that this forms the tangent34of the second sub-portion31and is intersected by the tangent32of the first sub-portion30at approximately the middle of the sliding bearing19. The magnitude of this angle, by which the tangent28on the running face25is twisted during the construction of the sliding bearing19, then determines the maximum deflection angle40.

Between the tangent34of the second sub-portion31and the tangent32of the first sub-portion30, an opening angle41is formed that corresponds to an angle of 180° minus the maximum deflection angle40. For correspondingly small bearing clearance26, which varies in the range of hundredths of one millimeter to tenths of one millimeter, the maximum deflection angle40accordingly also lies in the range of hundredths to tenths of one degree.

Furthermore, it may be provided that a fabrication-related transition radius42is formed between the first sub-portion30and the second sub-portion31. Preferably, the transition radius42will turn out to be as small as possible, so that the first contact line36and the second contact line37are as long as possible and thus the least possible surface pressure occurs between the sliding face24of the sliding bearing19and the running face25of the inner ring element11. Stated in other words, in the ideal case the first sub-portion30and the second sub-portion31will adjoin one another directly or if at all possible without transition radius42.

A further and as the case may be independent embodiment of the bearing element7is shown in a second exemplary embodiment inFIGS. 7 to 9, wherein once again like reference symbols or structural-part designations are used for like parts, as in the foregoingFIGS. 2 to 6. To avoid unnecessary repetitions, the detailed description in the foregoingFIGS. 2 to 6is invoked or reference is made thereto.

In the second exemplary embodiment of the bearing element7, it may be provided that the sliding bearing19is coupled with the inner ring element11and a sliding movement takes place between the sliding bearing19and the outer ring element14.

As is evident from the second exemplary embodiment, the sliding bearing19may be coupled with the inner ring element11and thus the receiving side23of the sliding bearing19may be formed on its inner side20. Corresponding to this, the sliding face24of the sliding bearing19in this exemplary embodiment is formed on its outer side21and cooperates with the inner side15of the outer ring element14, which in this exemplary embodiment is formed as the running face25.

The relationships between the first sub-portion30and the second sub-portion31of the sliding face24of the sliding bearing19and the running face24, cooperating therewith, of the outer ring element14behave in a manner analogous to the first exemplary embodiment already described inFIGS. 2 to 6. For the sake of brevity, the second exemplary embodiment will therefore not be described separately in detail, but instead the function is clearly evident to the person skilled in the art on the basis of the description for the first exemplary embodiment described inFIGS. 2 to 6or on the basis ofFIGS. 7 to 9.

Such a second exemplary embodiment of the bearing element7having an internally disposed sliding bearing19, as illustrated inFIGS. 7 to 9, will be used preferably when the outer ring element14is designed to be immovable and the inner ring element11together with the sliding-bearing element19can be twisted relative to the outer ring element14.

The exemplary embodiments show possible embodiment variants, wherein it must be noted at this place that the invention is not restricted to the specially illustrated embodiment variants of the same, but to the contrary diverse combinations of the individual embodiment variants with one another are also possible and, on the basis of the teaching of the technical handling by the subject invention, this variation possibility lies within the know-how of the person skilled in the art and active in this technical field.

The scope of protection is defined by the claims. However, the description and the drawings are to be used for interpretation of the claims. Individual features or combinations of features from the shown and described different exemplary embodiments may represent inventive solutions that are independent in themselves. The task underlying the independent inventive solutions may be inferred from the description.

All statements about value ranges in the description of the subject matter are to be understood to the effect that they jointly comprise any desired and all sub-ranges therefrom, e.g. the statement 1 to 10 is to be understood to the effect that all sub-ranges, starting from the lower limit 1 and the upper limit 10 are jointly comprised, i.e. all sub-ranges begin with a lower range of 1 or greater and end at an upper limit of 10 or smaller, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

Finally, it must be pointed out, as a matter of form, that some elements have been illustrated not to scale and/or enlarged and/or reduced for better understanding of the structure.

LIST OF REFERENCE NUMERALS

1Wind turbine2Gondola3Tower4Rotor5Rotor hub6Rotor blade7Bearing element8Radial force9Axial force10Tilting torque11First Inner ring element11aSecond Inner ring element12Inner side of inner ring element13Outer side of inner ring element14Outer ring element15Inner side of outer ring element16Outer side of outer ring element17Sliding bearing system18Axial spacing19First Sliding bearing19aSecond Sliding bearing20Inner side of sliding bearing21Outer side of sliding bearing22Central longitudinal axis23Outer side of sliding bearing24First Sliding face of first sliding bearing24aSecond Sliding face of second sliding bearing25First Running face25aSecond Running face26Bearing clearance27Spacing of inner ring elements28Tangent of first running face28aTangent of second running face29Angle of first running face29aAngle of second running face30First sub-portion30aThird sub-portion31Second sub-portion31aFourth sub-portion32First Tangent of first sub-portion32aThird Tangent of third sub-portion33First Angle of first sub-portion33aThird Angle of third sub-portion34Second Tangent of second sub-portion34aFourth Tangent of fourth sub-portion35Second Angle of second sub-portion35aFourth Angle of fourth sub-portion36First contact line37Second contact line38Fulcrum39Longitudinal middle axis40Maximum deflection angle41Opening angle42Transition radius