DE20203372U1 - Rotary bearing for systems exposed to moisture - Google Patents

Description

Pivoting bearings for systems exposed to moisture

The invention relates to a rotary bearing for systems exposed to moisture, e.g. for the blade bearing of a wind turbine, for ship winches, etc.

the like, with two connecting elements that can be rotated against each other, with at least one single or multi-row rolling bearing arranged between them, in particular for absorbing axial and/or radial loads and/or tilting moments, and with at least one seal for protecting the rolling bearing(s)

&iacgr;&ogr; from moisture and corrosion. The same applies to pure axial or radial rolling bearings or combination bearings

Man has always sailed the sea in ships; ever since iron was used for ship hulls and superstructures, the aggressive sea air, due to its corrosive properties, was a constant cause of rust on all iron parts, e.g. anchor winches, etc. However, all defects caused by this can usually be repaired at the nearest port with relatively little effort. The same applies to oil rigs, for example, where repairs can be carried out on site using the tools available.

On the other hand, it has recently become clear that the use of alternative energy sources is becoming more and more economical. In addition to hydroelectric power plants, wind turbines in particular have already proven their economic viability. Due to problems in acquiring land, with hostile residents and, in particular, with irregular wind blowing inland, the region beyond the coast has now been increasingly used by building so-called offshore wind turbines. Cheap land, no residents, constant, strong wind are the advantages - the aggressive sea air and the difficult maintenance are the disadvantages that have to be accepted. While this disadvantage was initially not given too much importance, it has now become apparent after several years of operation of many wind turbines in coastal areas that rust development is more severe than feared and, above all, that the long-term effects on a wind turbine can be catastrophic. The following are affected:

• · · ¹ year

especially the blade bearings, which serve to adjust the blades of the wind turbine more or less depending on the wind strength. These pivot bearings usually have a diameter of 1 to 3 meters or more and, due to their size, cannot be manufactured economically from stainless material. Instead, a galvanized layer on the one hand and one or more seals on the other serve as corrosion protection. However, this galvanized layer is rubbed through by the sealing ring in question, rust scars form, which wear out the seal, allowing moisture to get into the interior of the bearing, where

" Corrosion causes and thus leads to blocking of the bearing. This then

If the blade bearing in question needs to be replaced, a floating crane must be driven to the wind turbine in question, the blade must be lifted off and reinstalled after the blade bearing has been replaced. The costs for this are enormous and place a considerable burden on the economic viability of the wind turbine in question.

The described disadvantages of the prior art give rise to the problem initiating the invention of finding a way to prevent the formation of rust in the long term, at least in the area of the running surfaces or rolling elements of a rotary bearing exposed to aggressive environmental conditions, for example at sea, but also at coastal and inland locations.

This problem is solved by fixing a ring made of a non-corrosive material (corrosion-free ring) concentrically surrounding the axis of symmetry of a connecting element as part of a seal, against which rests an elastic sealing element (elastic ring), also ring-shaped, attached to the other connecting element.

The invention dispenses with direct contact between a sealing ring fixed to a connecting element on the one hand and the galvanized layer of the other, oppositely rotating connecting element on the other hand within the main seal. This also avoids the abrasion of the galvanized layer that inevitably occurs as a result of the contact pressure of the seal and consequently the exposure of the bare metal in the area of the main

Seal, which would result in the formation of rust under the main seal and thus the ingress of moisture. Instead, a ring made of a corrosion-free material is used that does not require galvanization or other rust protection and yet is never subject to corrosion. The main seal therefore remains intact over the long term and can thus protect the sensitive parts of the relevant rotary bearing against the ingress of moisture.

_r protect.

" It has proven to be advantageous that the corrosion-free ring is arranged in an area of the relevant connection element which is set back in the axial direction relative to the corresponding end face of the other connection element. This makes it possible to fix the sealing ring which comes into contact with it to a casing area of the axially projecting connection element and to design it in such a way that it surrounds the corrosion-free ring in the shortest possible way.

The corrosion-free ring should have a constant cross-section over its circumference so that the elastic sealing ring is not subjected to deformation when the pivot bearing is rotated. This cross-section itself can be chosen almost arbitrarily; however, at least the contact surface should be designed as a flat or only slightly curved surface so that the elastic sealing ring has no problems in creating a complete seal. A polygonal, particularly rectangular, cross-section has therefore proven to be useful.

Given the large dimensions of some rotary bearings mentioned above, the elastic sealing ring must have a relatively hard consistency in order to be reliably held in place and to remain dimensionally stable. The abrasion effect caused by this on the corrosion-free ring cannot therefore be neglected; to prevent premature wear of the corrosion-free ring, the invention therefore provides for selecting a material with a high abrasion resistance, which should be higher than the abrasion resistance of the sealing ring used. The use of a metal ring, particularly made of brass, has proven particularly effective in this context.

For its fastening, the corrosion-free ring can be inserted into a groove or recess running around the axis of symmetry of the respective connecting element. This allows a mechanically very stable form fit to be formed; in addition, any gap between the corrosion-free ring and the respective connecting element can be avoided, so that a bypass effect for penetrating

- moisture is completely excluded. Alternatively or in addition to the ring being placed in a groove, it can also be attached using rivet pins or screws. Even caulking (making a joint fit,

&iacgr;&ogr; Inserting the ring into the relevant groove and deforming the groove edges), gluing or soldering is conceivable.

In a first embodiment, the corrosion-free ring is pressed or caulked into the groove or recess. For this purpose, the cross-sections of the interlocking parts of the ring and groove can be dimensioned in the manner of a press fit. A joint fit is sufficient for caulking, since the fixing is then brought about by deformation of the groove or recess edges. On the other hand, this connection technique is the simplest option and leads to complete centering of the ring on the connecting element. Since the corrosion-free ring is almost free from external forces during operation, particularly in the axial direction of the pivot bearing, a stable and permanent connection is achieved in this way.

Another method for fixing the corrosion-free ring in the groove or recess involves gluing these parts together. Such a connection can be made without the use of a press; in addition, for example, a synthetic resin-based adhesive with electrically insulating properties can be used to electrically insulate a corrosion-free metal ring from the groove and thus also from the body of the connection element in question, so that no electrochemical elements can form.

On the other hand, it is also possible to cast the corrosion-free ring into the groove, resulting in a particularly tight connection between the ring and the connecting element.

If the corrosion-free ring is completely recessed into a groove or recess and is approximately flush with its edges, the elastic sealing ring can rest on - a non-enclosed side of the corrosion-free element,

In another embodiment, the part of the

&iacgr;&ogr; corrosion-free ring exclusively fixes it, while another part of the corrosion-free ring projects beyond the front side of the respective connection element in order to provide the actual sealing contact surface there.

Although the corrosion-free ring could also be arranged on a jacket surface of a connecting element, inserting a closed ring into a front-side groove of the connecting element is considerably simpler and therefore generally preferable.

If the height of the raised area of the corrosion-free ring corresponds approximately to the depth of the groove that accommodates it, a balanced relationship is created between the size or volume of the ring on the one hand and the form or force closure that serves to stabilize it on the other.

A particularly good sealing effect is achieved when the elastic sealing ring rests on two opposite sides of the raised area of the corrosion-free ring. This allows the corrosion-free ring with its two opposite sides to take on a centering effect on the elastic sealing ring and thus contributes to a stable fit of the elastic sealing ring and thus to a consistent, optimal sealing effect.

When inserting the corrosion-free ring into a groove of the relevant connecting element, two adjacent jacket areas of the corrosion-free ring can each be aligned with one of two outer surfaces of this connecting element,

which are located in the area of the groove. The resulting smooth surface transition avoids unnecessary edges which could cause damage to the elastic sealing ring and therefore allows a further development of the invention, whereby the elastic sealing ring is in sealing contact with one or both of these casing sides of the corrosion-free ring.

, By designing the contact area(s) of the elastic ring with the corrosion-free ring (each) as a sealing lip, an elastic contact force that supports the sealing contact &iacgr;&ogr; can be realized by utilizing the material properties of the elastic sealing ring, such that the sealing lips are pressed with their end areas against the corrosion-free ring due to a pre-tension of the elastic sealing ring.

The invention can be further developed in such a way that, viewed from the corrosion-free ring, a secondary sealing lip is provided beyond one of the two main sealing lips (each). Such secondary sealing lips keep external influences such as dust or abrasion particles from the bearing away from the main sealing lips and thus ensure that the main seal remains functional in the long term even without regular inspection.

The secondary sealing lip facing away from the rolling bearing area to be sealed can be pressed elastically onto the galvanized or other anti-rust coated area of the relevant connecting element. Even if the sealing effect of the secondary sealing lip decreases over time due to abrasion, this has no negative effect on the main seal.

Preferably, the secondary sealing lip facing the rolling bearing area to be sealed extends into the air gap between the two connecting elements. There it performs a similar function to the outer secondary sealing lip against abrasion particles from the pivot bearing itself, but at the same time is itself protected from external influences.

The secondary sealing lip protruding into the air gap can have a barb-shaped cross-section and can be elastically expanded to form a seal on the opposing surfaces of the two connecting elements. This secondary sealing lip thus automatically generates the required contact pressure. On the other hand, due to the barb cross-section, it also acts as a valve for the lubricating grease, in that lubricating grease pressed into the pivot bearing under pressure can pass through this secondary sealing lip, but is then held back and can therefore lubricate the main sealing lips.

It is within the scope of the invention that on the part of the elastic sealing ring that spans the air gap, in particular beyond the secondary sealing lip that projects into the air gap, an extension running along this sealing ring in the circumferential direction with a bead-like or spring-like cross-section is formed, which can be inserted into a groove-shaped recess of the relevant connecting element to fasten the elastic sealing ring. While the corrosion-free ring guides the elastic sealing ring in the area of the relevant connecting element and preferably in the axial direction of the rotary bearing, it is the responsibility of the (front-side) extension of the elastic sealing ring to stabilize it in the area of the other connecting element as well.

In order to produce a high anchoring force through elastic spreading forces of the extension with a bead-like or spring-like cross-section within the groove receiving it, the extension can be provided with profiles, e.g. have a sawtooth-shaped cross-section, whereby the elevations of these profiles are pressed together by the narrower groove cross-section.

According to a further feature of the invention, the depth of the groove-shaped recess for receiving the extension of the elastic sealing ring runs approximately perpendicular to the air gap between the two connecting elements, so that the elastic sealing ring is stabilized and anchored in the radial direction due to its extension engaging in this groove and can therefore, for example,

cannot expand or become detached from its anchorage due to internal overpressure caused by the injection of lubricating grease.

Relocating the groove-shaped recess for the lateral extension of the elastic sealing ring to an area outside the air gap makes it easier to insert the ring extension into the groove provided for it.

To protect against corrosion, one or both connection elements outside the sealed area can be galvanized or provided with another anti-rust coating. Because the ring is made of corrosion-free material, the main seal remains intact, even if part of the anti-rust coating is removed by external influences, friction, etc., and corrosion sets in as a result. The main seal forms an insurmountable barrier to corrosion.

If the groove-shaped recess(es) for receiving the corrosion-free ring and/or an extension of the elastic sealing ring is incorporated, in particular screwed in, after the rust protection treatment of the connection element in question, in particular after a galvanizing step, the roughness of the groove boundary walls can be reduced to a minimum, which facilitates the fastening of the corrosion-free ring.

Finally, it is in accordance with the teaching of the invention that the entire area between the main and/or secondary sealing lips is filled with lubricating grease. On the one hand, this lubricating grease is responsible for ensuring that the main sealing lips slide on the corrosion-free ring with as little friction as possible. In addition, it serves to provide additional protection for the main sealing lips against dust, abrasion or rust particles by embedding them in the lubricating grease and thus preventing them from reaching the main sealing lips.

Further features, details, advantages and effects based on the invention emerge from the following description of preferred embodiments of the invention and from the drawing. Here:

Fig. 1 the hub area of the three-bladed rotor of a wind turbine;

Fig. 2 a blade bearing used in the wind turbine of Fig. 1

usable rotary bearing;

Fig. 3 is a section through the pivot bearing of Fig. 2 along the line Il - II;

Fig. 4 shows detail IV from Fig. 3 in an enlarged view;

&iacgr;&ogr; Fig. 5 another embodiment of the invention in a representation

according to a section of Fig. 4; and

Fig. 6 shows a further modified embodiment of the invention in a

the representation corresponding to Fig. 4.

Fig. 1 shows the upper part of the tower 1 of a wind turbine 2. The machine house 3, which can be pivoted about a vertical axis, carries a hub 4 which can be rotated about a horizontal axis and to which three rotor blades 5 extending in a radial direction are attached to capture the wind energy. In order to be able to adapt the wind pressure to be absorbed by the rotor blades 5 to the respective wind speed, they can be rotated relative to the hub 4 about axes parallel to their longitudinal axis. This movement is achieved by a rotary bearing 6, as shown separately in Fig. 2.

Two ring-shaped connecting elements 7, 8 can be seen which can be rotated relative to one another and which are attached to the hub 4 on the one hand and to the rear end face of the relevant rotor blade 5 on the other. For this purpose, the two connecting elements 7, 8 which are arranged concentrically to one another are each provided with a plurality of fastening holes 13, 14 arranged in a ring shape and running through between the two end faces 9, 10; 11, 12.

From Fig. 3 it can also be seen that the connecting elements 7, 8 each have an approximately rectangular cross-section with approximately the same height. The connecting elements 7, 8 are mostly arranged one inside the other, but the inner diameter of the outer connecting element 7 is larger than the outer diameter of the inner connecting element 8, so that an air gap 15 of approximately constant width is formed between them. In the two mutually facing

- A circumferential groove 18,19 with the cross-section of a circular segment is machined into the lateral surfaces 16, 17 of the two connecting elements 7, 8, so that a toroidal raceway for spherical rolling elements 20 is formed.

Î&ogr; results. However, in other embodiments, rolling elements with a different shape can also be used, for example cylindrical or needle-shaped rolling elements. Several rows of rolling elements can also be provided.

The connecting elements 7, 8 preferably consist of a tempering steel suitable for such applications, but which is not corrosion-free. Therefore, outside the air gap 15 they are covered with a zinc layer 21 that protects against corrosion.

Since the two connecting elements 7, 8 are offset from one another in the axial direction of the rotary bearing 6, in the area of the front ends of the air gap 15, one end face 10, 11 of a connecting element 7, 8 protrudes from the relevant end face 12, 9 of the other connecting element 8, 7. A seal 22, 23 is provided in each of these areas. In the illustrated embodiment of a rotary bearing 6, the structure of both seals 22, 23 is identical, but this is not mandatory.

A seal 22, 23 comprises two components, namely a ring 24 made of a corrosion-free material on the one hand and a ring 25 made of a (limited) elastic material on the other hand.

The corrosion-free ring 24 can be made of brass or another non-rusting metal or metal alloy, for example. It can also be made of plastic, provided it has a sufficiently abrasion-resistant

surface finish. If necessary, the surface of the ring 24 can also be hardened or provided with a wear-resistant coating.

In the embodiment shown, the corrosion-free ring 24 has a rectangular cross-section, wherein its width in the axial direction of the pivot bearing 6 is approximately 1.5 to 5 times, in particular approximately 3 times as large as its thickness in the radial direction of the pivot bearing 6. Other cross-sectional shapes are possible.

This ring 24 is received in a groove 26 at approximately half of its cross section,

&iacgr;&ogr; which is arranged in the front side 9 of a connecting element 7, which is set back relative to the other connecting element 8, concentrically to the axis of rotation of the pivot bearing 6. The cross-section of this groove 26 corresponds in terms of its width to the radial thickness of the ring 24, while the groove depth corresponds approximately to half the ring width. In the embodiment according to Fig. 4, the corrosion-free ring 24 is fixed in the groove 26 by caulking.

On the other hand, as Fig. 5 shows, it is also possible to glue the corrosion-free ring 24 into the groove 26, for example. If an electrically non-conductive adhesive 27, for example made of epoxy resin or the like, is used for this purpose, an electrical insulation can be created at the same time between the corrosion-free ring 24 and the relevant connection element 7, which prevents the formation of an electrochemical element due to the collision of two different metals.

From Fig. 4 it can also be seen that the groove recesses 26 or the rings 24 of the two seals 22, 23 inserted therein divide the surface of the respective connection element 7 into an external, galvanized region 21 on the one hand and the air gap 15 on the other hand, which is sealed to the outside and therefore does not have to be galvanized.

The elastic sealing ring 26 forms the counterpart to the corrosion-free ring 24 and is therefore fixed to the other connecting element 8 in a largely torsion-proof manner. For this purpose, the front side 9 of the connecting element 7 is connected to the

_a « .« ·· ·· ·■· ■»■*■·■■

A circumferential groove 29 is machined into the section 28 of the outer surface 17 of the other connecting element 8 that projects beyond the corrosion-free ring 24, into which a front-side extension 30 of the elastic sealing ring 25 engages. This extension 30 has a cross-section with sawtooth-shaped elevations that press together when pressed into the groove 29 and thereby ensure a firm frictional connection in the groove 29.

Since no undercuts are provided within the air gap 15, the seal 22, 23 can be replaced without dismantling the connecting elements 7, 8. This is particularly important in the event of damage or long-term degeneration, for example as a result of the effects of ozone or solar radiation or due to material fatigue, which cannot be ruled out.

This extension 30 is located on a front side 31 of the elastic ring 25, which rests on the outer surface 17 of the relevant connecting element 8. From here, the outer cross-sectional edge of the elastic ring 25 runs over the air gap 15 and the corrosion-free ring 24 in a wide arc 32 to the galvanized front surface 9 of the other connecting element 7. There, a secondary sealing lip 33 is provided, which rests along a narrow area on the connecting element 7.

The inner or lower region 34 of the sealing ring 25 roughly follows its outer, curved course 32, so that the corrosion-free ring 24 is also overlapped by it. On both sides of this ring 24, a sealing lip 35, 36 (main sealing lips) extends downwards from the lower region 34 of the elastic sealing ring 25. These two sealing lips 35, 36 are spaced apart in their upper region by a distance that is greater than the (radial) thickness of the corrosion-free ring 24, but approach each other in their lower region and are therefore pressed against the radially outer or inner side 37, 38 of the ring 24 with elastic deformation. In addition to the actual sealing, this has the further effect of guiding the elastic ring 25 in the radial direction.

As the outer secondary sealing lip 33 is supported on the connecting element 7, it supports the elastic sealing ring 25 together with the extension 30 and thus keeps the main sealing lips at a distance above the end face 9 of the relevant connecting element 7. The main sealing lips 35, 36 therefore slide exclusively on the corrosion-free ring 24, and an optimal low level of wear can be ensured by a suitable material pairing.

Finally, on the underside 34 of the elastic sealing ring 25, approximately in the extension of its front surface 31, there is another secondary sealing lip 39

γ is formed on the sealing lip 39, which projects into the air gap 15. This secondary sealing lip 39 is given a barb-like cross-section by an extension 41 attached to its inner end 40 and extending obliquely outwards. As a result, the secondary sealing lip 39 is elastically deformed when introduced into the air gap 15 and generates an expansion force which ensures a high contact pressure against both outer surfaces 16, 17 of the connecting elements 7, 8. The main seal 35, 36 is thus protected from abrasion particles from the roller bearing area 15-20.

On the other hand, the extension 41 can be pushed aside in the event of excess pressure from the grease pressed into the pivot bearing 6, so that the grease can reach the area of the main seal 35, 36, where it is then held in place after the extension 41 springs back. This ensures that all cavities within the seal 22, 23 up to its outermost secondary sealing lip 33 are and remain completely filled with grease. In addition, the fact that the edge 42 (see Fig. 4) is gripped by the outer secondary sealing lip 33 on the one hand and the extension 41 of the inner secondary sealing lip 39 on the other hand leads to a particularly high degree of dimensional stability (good standing) and thus to a long-term guarantee of the sealing effect.

The same applies to the seal 43 from Fig. 6. This differs from the seal 22 from Fig. 4 primarily in that the corrosion-free ring 44 is not inserted in a groove 26 of a connecting element 7, but in a groove 45 with an approximately rectangular or even square cross-section, which is located in the area of the edge between the front side 9 of the relevant connecting element 7 and

whose air gap-side jacket surface 16 is located. The cross section of the corrosion-free ring 44 is approximately adapted to the groove cross section, so that its jacket sides 46, 47 are flush with the relevant surfaces 9, 16 of the connecting element 7. The corrosion-free ring 44 can be fixed, for example, with adhesive, as in the embodiment according to Fig. 5.

. In accordance with the changed geometry of the corrosion-free ring 44 and its casing sides 46, 47 not encompassed by the connecting element 7, the elastic ring 48 is also modified compared to the elastic ring 25: The main sealing lips 49, 50 are pressed elastically against one of the two casing sides 46, 47 of the corrosion-free ring 44. The protruding, free edge 51 of the corrosion-free ring 44 has a similar stabilizing and anchoring effect as the raised area of the corrosion-free ring 24 from Fig. 4.

Claims (28)

1. Pivot bearing ( 6 ) for systems exposed to moisture, e.g. for the blade bearing of a wind turbine ( 2 ), for ship winches or the like, with two connecting elements ( 7 , 8 ) that can be rotated relative to one another, with at least one single- or multi-row roller bearing ( 18-20 ) arranged between them, in particular for absorbing axial and/or radial loads and/or tilting moments, and with at least one seal ( 22 , 23 ; 43 ) for protecting the roller bearing(s) ( 18-20 ) against moisture and corrosion, characterized in that, as part of a seal ( 22 , 23 ; 43 ), an annular element ( 24 ; 44 ) made of a non-corrosive material is fixed to a connecting element ( 7 ) concentrically surrounding its axis of symmetry (corrosion-free ring), to which a An elastic sealing element ( 25 ; 48 ) which is also ring-shaped and is attached to the connecting element ( 8 ) (elastic ring). 2. Pivot bearing according to claim 1, characterized in that the corrosion-free ring ( 24 ; 44 ) is arranged in a region ( 9 ) of the respective connecting element ( 7 ) which is set back in the axial direction relative to the corresponding end face ( 11 ) of the other connecting element ( 8 ). 3. Pivot bearing according to claim 1 or 2, characterized in that the corrosion-free ring ( 24 ; 44 ) has an approximately polygonal, in particular rectangular, cross-section. 4. Pivot bearing according to one of claims 1 to 3, characterized in that the corrosion-free ring ( 24 ; 44 ) has a higher abrasion resistance than the elastic sealing ring ( 25 ; 48 ). 5. Pivot bearing according to one of the preceding claims, characterized in that the corrosion-free ring ( 24 ; 44 ) consists of a metallic material, in particular a metal alloy, for example brass. 6. Pivot bearing according to one of the preceding claims, characterized in that the corrosion-free ring ( 24 ; 44 ) is inserted in a groove ( 26 ) or recess ( 45 ) surrounding the axis of symmetry of the respective connecting element ( 7 ). 7. Pivot bearing according to claim 6, characterized in that the corrosion-free ring ( 24 ; 44 ) is pressed or mortised into the groove ( 26 ) or recess ( 45 ). 8. Pivot bearing according to claim 6 or 7, characterized in that the corrosion-free ring ( 24 ; 44 ) is glued ( 27 ) into the groove ( 26 ) or recess ( 45 ). 9. Pivot bearing according to claim 6, characterized in that the corrosion-free ring ( 24 ; 44 ) is cast into the groove ( 26 ) or recess ( 45 ). 10. Pivot bearing according to one of claims 6 to 9, characterized in that the elastic sealing ring ( 25 ; 48 ) rests on a side of the corrosion-free ring ( 24 ; 44 ) not encompassed by the connecting element ( 7 ). 11. Pivot bearing according to one of claims 6 to 10, characterized in that the corrosion-free ring ( 24 ; 44 ) projects at least partially beyond the relevant end face or casing side ( 9 , 16 ) of the relevant connecting element ( 7 ). 12. Pivot bearing according to claim 11, characterized in that the height of the raised region of the corrosion-free ring ( 24 ) corresponds approximately to the depth of the groove ( 26 ) receiving it. 13. Pivot bearing according to claim 11 or 12, characterized in that the elastic sealing ring ( 25 ) rests on one or both of the opposing side flanks ( 37 , 38 ) of the raised region of the corrosion-free ring ( 24 ). 14. Pivot bearing according to one of claims 6 to 10, characterized in that two adjacent casing regions ( 46 , 47 ) of the corrosion-free ring ( 44 ) each terminate approximately flush with one of two surfaces ( 9 , 16 ) which lie in the region of the groove ( 45 ) receiving the ring ( 44 ). 15. Pivot bearing according to claim 14, characterized in that the elastic sealing ring ( 48 ) rests against one or two adjacent casing regions ( 46 , 47 ) of the corrosion-free ring ( 44 ). 16. Pivot bearing according to one of the preceding claims, characterized in that the contact area(s) of the elastic ring ( 25 ; 48 ) with the corrosion-free ring ( 24 ; 44 ) (each) is designed as a sealing lip ( 35 , 36 ; 49 , 50 ). 17. Pivot bearing according to claim 16, characterized in that the sealing lip(s) ( 35 , 36 ; 49 , 50 ) is/are pressed with its end region(s) against the corrosion-free ring ( 24 ; 44 ) due to a prestressing of the elastic sealing ring ( 25 ; 48 ). 18. Pivot bearing according to claim 16 or 17, characterized in that, viewed from the corrosion-free ring ( 24 ; 44 ), a secondary sealing lip ( 33 , 39 ) is provided beyond one (of the two) main sealing lips ( 35 , 36 ; 49 , 50 ) (in each case). 19. Pivot bearing according to claim 18, characterized in that the secondary sealing lip ( 33 ) facing away from the rolling bearing region ( 15-20 ) to be sealed is elastically pressed against the galvanized region or region provided with another rust-protection coating ( 21 ) of the relevant connecting element ( 7 ). 20. Pivot bearing according to claim 18 or 19, characterized in that the secondary sealing lip ( 39 ) facing the rolling bearing area ( 15-20 ) to be sealed projects into the air gap ( 15 ) between the two connecting elements ( 7 , 8 ). 21. Pivot bearing according to claim 20, characterized in that the secondary sealing lip ( 39 ) projecting into the air gap ( 15 ) has a barb-shaped cross-section ( 40 , 41 ) and, by elastic spreading, seals against the opposing surfaces ( 16 , 17 ) of the two connecting elements ( 7 , 8 ). 22. Pivot bearing according to one of the preceding claims, characterized in that on the part ( 31 ) of the elastic sealing ring ( 25 ; 48 ) which spans the air gap ( 15 ), in particular beyond the secondary sealing lip ( 39 ) protruding into the air gap (15), an extension ( 30 ) running along this sealing ring ( 25 ; 48 ) in the circumferential direction and having a bead-like or spring-like cross-section is formed in order to fasten the elastic sealing ring ( 25 ; 48 ) in a groove-shaped recess ( 29 ) of this connecting element ( 8 ). 23. Pivot bearing according to claim 22, characterized in that the extension ( 30 ) with a bead-like or spring-like cross-section has profiles, for example with a sawtooth-shaped cross-section, in order to produce a high anchoring force in the groove-shaped recess ( 29 ) by elastic spreading forces. 24. Pivot bearing according to claim 22 or 23, characterized in that the depth extension of the groove-shaped recess ( 29 ) for receiving the extension ( 30 ) of the elastic sealing ring ( 25 ; 48 ) runs approximately perpendicular to the air gap ( 15 ) between the two connecting elements ( 7 , 8 ). 25. Pivot bearing according to one of claims 22 to 24, characterized in that the groove-shaped recess ( 29 ) for receiving the extension ( 30 ) of the elastic sealing ring ( 25 ; 48 ) is located outside the air gap ( 15 ). 26. Pivot bearing according to one of the preceding claims, characterized in that one or both connecting elements ( 7 , 8 ) outside the sealed area ( 15-20 ) are provided with a galvanizing or other rust protection layer ( 21 ). 27. Pivot bearing according to claim 26, characterized in that the groove-shaped depression(s) ( 26 , 29 ) for receiving the corrosion-free ring ( 24 ) and/or an extension ( 30 ) of the elastic sealing ring ( 25 ; 48 ) is (are) incorporated, in particular screwed, after the rust protection treatment of the respective connecting element, in particular after a galvanizing step. 28. Pivot bearing according to one of the preceding claims, characterized in that all cavities in the entire sealing area ( 22 , 23 ; 43 ), in particular also the area between the main and/or secondary sealing lips ( 33 , 35 , 36 , 39 ), are filled with lubricating grease.