GROSSWÄLZLAGER

Description

[0001] The invention relates to a large rolling bearing with the features of the preamble of claim 1.

[0002] In large slewing bearings, particularly in blade bearings for wind turbines, static seals are used to prevent grease leakage. "Static" means that the seal provides a seal during both steady-state and discontinuous rotational movements of the bearing's inner or outer rings. During operation, the blade bearing performs a pivoting motion to adjust the blade angle for optimal wind power utilization.

[0003] The primary function of blade bearing seals is twofold: first, to prevent grease from escaping the bearing interior, thus preventing environmental contamination and lubricant depletion; and second, to prevent the ingress of solid contaminants and liquids from the outside, which could impair the bearing's function, for example, through corrosion or mechanical damage. Therefore, blade bearing seals must guarantee complete tightness during operation. Simultaneously, the seal must bridge any changes in the sealing gap caused by deformation and displacement due to load-induced radial movement of the rings relative to each other without leakage. These changes in the sealing gap are particularly significant in large bearings and can easily amount to several millimeters.

[0004] Furthermore, it is necessary to relubricate the bearing at regular intervals to ensure normal operation and a sufficient service life. However, there is a risk that high local pressures may occur during relubrication, which can lead to grease leakage and even damage and leakage of the seal.

[0005] Another essential characteristic that a gap seal for large slewing bearings must possess is its reliable installation capability. It must be ensured that the seal reliably assumes a defined position within the installation space, a position that remains unchanged during operation and under (local) overpressure. This aspect is particularly crucial for large bearings, as even slight misalignment can lead to leaks and seal failure.

[0006] From EP 2 672 133 B1, a large rolling bearing with a gap seal that seals the gap between the bearing rings is known. A gap seal for large rolling bearings must meet various requirements, which are listed above and below.

[0007] In large slewing bearings, the widening of the gap between the bearing rings, caused by the loads acting on the rings during operation, increases with the bearing ring diameter for a given load. This applies, for example, to blade bearings of wind turbines, which are subjected to both high static loads (e.g., bending moments due to the weight of the rotor blade) and high dynamic loads (e.g., due to the wind-induced forces and moments transmitted by the rotor blade). As a rule of thumb, the gap between the bearing rings widens by approximately 1 mm for every meter of bearing ring diameter.

[0008] A reliably functioning gap seal must be able to compensate for such gap widening without losing its sealing effect.

[0009] Furthermore, a gap seal must reliably seal the gap between the bearing rings both in the static case (i.e., in the case of blade bearings, e.g., when the rotor blade is stationary) and in the dynamic case (i.e., in the case of blade bearings, e.g., when the rotor blade rotates (at different speeds) around the rotor hub).

[0010] A gap seal must also be able to withstand an overpressure inside the bearing, such as 3 bar or more, which may occur during operation or be deliberately introduced into the bearing, without negatively affecting the sealing effect.

[0011] Finally, the gap seal must be as easy and safe to install as possible; in particular, incorrect installation of the gap seal that negatively impairs the sealing effect must be avoided.

[0012] The gap seal known from EP 2 672 133 B1 cannot satisfactorily meet the various requirements described above, especially for bearings with large diameters.

[0013] European patent application EP 3 236 096 A1 relates to the field of large bearings used in the wind power industry, and in particular to the field of oil seals for preventing the loss of lubricants in such large bearings designed as ball or roller bearings in wind turbines. Specifically, EP 3 236 096 A1 discloses an oil seal for a wind turbine bearing, which is arranged between an outer ring and an inner ring. In the embodiment according to Fig. 2 An axial sealing lip 13 is provided, which is arranged such that it is pushed away from the sealing surface of the groove 7 with which it interacts by overpressure inside the bearing. As a result, this sealing lip 13 cannot contribute to improving the sealing of the bearing in the case of increased internal bearing pressure. In the embodiment according to Fig. 3 EP 3 236 096 A1 discloses an oil seal in which axially pre-tensioned lips are arranged, these lips being designed as double lips (sealing lips 18, 19) in the inner region. Using the groove 7 in the inner ring 2 as a reference, there is an upper lip 17 and two lower lips 18, 19 in the inner region of the groove 7. This achieves a labyrinth oil seal, which increases the resistance to the flowing fluid. In the case of increased internal bearing pressure, the upper sealing lip 17 is again, analogous to the sealing lip 13 in the embodiment according to Fig. 2 , is pushed away from the sealing surface with which it interacts and therefore does not contribute to sealing the bearing against increased internal bearing pressure. A disadvantage of the oil seals known from EP 3 236 096 A1 is that they are specifically designed for liquid oil as a lubricant. In particular, they are not suitable for sealing large rolling bearings lubricated with grease, which exhibit an overpressure inside the bearing during operation.

[0014] Document WO 2017 / 065238 A1 describes a gap seal for large rolling bearings, which has two sealing lips. A projection 11 is provided on the outer ring 2, which is intended to prevent the main sealing lip 14 from being forced out of the sealing gap in the event of excessive overpressure inside the bearing.

[0015] From DE 10 2010 053 203 A1 a sealing element for sealing between two moving components is known, in particular for the application in sealing systems or elements for rotary joints in wind turbines, especially in the area of ​​a rotor or main bearing or a blade bearing or also a nacelle bearing.

[0016] The object of the invention is to provide a large rolling bearing with improved sealing. In particular, the sealing against the escape of lubricating grease when the bearing is operated with overpressure inside the bearing is to be improved.

[0017] This problem is solved by a large slewing bearing with the features of claim 1. Advantageous further developments result from the dependent claims, the following description and the drawings.

[0018] The large rolling bearing according to the invention comprises a first bearing ring, a second bearing ring and a gap between the first and the second bearing ring, wherein an annular gap seal is arranged in the gap, with which the escape of lubricant from the interior of the large rolling bearing to the outside is prevented, wherein the gap seal has a sealing base which is received in an anchoring groove provided in the first bearing ring, wherein the gap seal has a first sealing lip, a second sealing lip and a third sealing lip, wherein the first sealing lip bears against a first sealing surface formed on the second bearing ring, wherein the second and the third sealing lips are received in a sliding groove arranged in the second bearing ring such that the second sealing lip bears against a second sealing surface bounding the sliding groove and the third sealing lip bears against a third sealing surface bounding the sliding groove.where, viewed from the outside of the large rolling bearing, the first sealing surface is arranged in front of the second sealing surface and the second sealing surface is arranged in front of the third sealing surface.

[0019] The gap seal has a fourth sealing lip arranged in the gap, which extends into the gap and is supported on a fourth sealing surface, wherein the fourth

[0020] a sealing surface is formed on a section of the second bearing ring which limits the gap in the radial direction, and wherein the fourth sealing surface is arranged behind the third sealing surface when viewed from the outside of the large rolling bearing.

[0021] According to the invention, it is provided that the first, second and third sealing lips assume a defined, stable position in the installation space when there is overpressure inside the bearing, and that the axial second sealing lip is pressed onto the second sealing surface and the axial third sealing lip is pressed onto the third sealing surface by the overpressure.

[0022] The gap seal according to the invention achieves an overpressure resistance of greater than 5 bar overpressure, since, with small to medium sealing gap expansions, only the sealing base and the fourth sealing lip are subjected to overpressure, while the first, second, and third sealing lips assume and maintain a defined, stable position in the installation space. This has the positive effect that the rotational resistance also remains low, since, in particular, the axial second and axial third sealing lips are not additionally pressed against the running surface by the overpressure as long as the fourth sealing lip is pressed against the fourth sealing surface by the overpressure.

[0023] If the sealing gap widens to such an extent that the fourth sealing lip no longer makes proper contact with the fourth sealing surface, then, in the gap seal according to the invention, the third and second sealing lips are pressed against their respective corresponding sealing surfaces in the sliding groove by the overpressure inside the bearing. This continues to prevent the escape of lubricant, in particular grease, even if the fourth sealing lip no longer provides a seal.

[0024] The complete sealing of the rolling bearing according to the invention is achieved by a combination of the first, second, third, and fourth sealing lips. The additional fourth sealing lip prevents grease from escaping into the gaps between the seal and the mounting chamber during operation and from being subsequently transported further by "pumping mechanisms." Only in cases of very large enlargements of the sealing gap, such as those that can occur under extreme loads during bearing operation, can grease enter the gaps between the seal and the mounting chamber. However, these operating conditions occur only rarely, so that no excessive amount of grease penetrates the gap between the seal and the mounting chamber uncontrollably. The entry of a small amount of grease under these operating conditions with extreme loads is even desirable in order to lubricate all sealing areas and thus achieve low rotational resistance and a longer service life of the seal.

[0025] The fourth sealing lip provided according to the invention significantly increases the sealing performance of the gap seal compared to the generic gap seal. By positioning the fourth sealing surface behind the third sealing surface when viewed from the outside of the large-diameter bearing, an additional radial sealing plane is achieved in conjunction with the fourth sealing lip, compared to the prior art.

[0026] The sealing effect of the gap seal according to the invention is significantly improved compared to the prior art, particularly when there is increased internal pressure inside the rolling bearing, because the fourth sealing lip, arranged in the gap and interacting with the fourth sealing surface, is pressed against the fourth sealing surface formed on the second bearing ring by the internal bearing pressure. This increases the sealing effect of the gap seal, even when the bearing rings move radially relative to each other under load. An overpressure present inside the bearing during operation ensures that the fourth sealing lip is pressed against the fourth sealing surface due to its elasticity, so that the sealing effect of the fourth sealing lip is maintained even when the bearing rings move radially relative to each other.Furthermore, this reduces the risk of the gap seal being forced out of its installation position by overpressure inside the bearing.

[0027] An overpressure inside the bearing also causes pressure relief of the sealing base body and mechanical relief (tension, bending and shear) of the sealing foot and the sealing base body.

[0028] In this way, the gap seal according to the invention achieves an overpressure resistance of greater than 5 bar, since with small to medium sealing gap expansions only the sealing base and the fourth sealing lip are subjected to overpressure, while the first, second, and third sealing lips assume and maintain a defined, stable position in the installation space. This has the positive effect that the rotational resistance also remains low, since in particular the axial second and axial third sealing lips are not additionally pressed against the running surface by the overpressure, which would increase friction and thus rotational resistance and wear.

[0029] Overall, the gap seal according to the invention, the manner of its arrangement in the gap between the bearing rings and the interaction of the fourth sealing lip with a fourth sealing surface formed on the second bearing ring provide a large rolling bearing which, compared to the prior art, has a significantly improved sealing and less wear and thus a longer service life.

[0030] The gap seal can be designed as an extruded sealing profile and can consist in particular of the materials NBR (Nitrile Butadiene Rubber), HNBR (Hydrogenated Nitrile Butadiene Rubber) or FKM (Fluoro-rubber).

[0031] According to one embodiment of the large rolling bearing according to the invention, the fourth sealing lip encloses an angle of attack with a first reference plane containing the fourth sealing surface, wherein the fourth sealing lip has a width in a transition area adjacent to a base body of the gap seal, wherein the ability of the bearing to compensate for an enlargement of the sealing gap is adjustable by selecting the angle of attack and the width as well as a length of the fourth sealing lip perpendicular to the width.

[0032] The first reference plane can be cylindrical.

[0033] The angle of attack influences the contact force with which the fourth sealing lip is pressed against the fourth sealing surface. The larger the angle of attack, the greater the contact force. The angle of attack and the contact force are also crucial for maintaining the sealing effect of the fourth sealing lip when the gap between the bearing rings widens due to relative movement. A gap seal with a high contact force of the fourth sealing lip against the fourth sealing surface when installed can maintain the sealing effect of the fourth sealing lip even with larger gap widenings than is possible with gap seals with lower contact force or a smaller angle of attack. The angle of attack of the fourth sealing lip is therefore a design parameter for the gap seal, allowing for targeted control of its sealing effect.The gap seal can be adapted to the expected widening of the gap between the bearing rings during operation of the large slewing bearing using this parameter. This makes it possible to ensure a tight seal for different bearing ring loads and the resulting varying degrees of gap widening in identical large slewing bearings by using different gap seals that differ only in their angle of attack.

[0034] In addition to the preload of the fourth sealing lip against the fourth sealing surface in the installed position of the gap seal, achieved by selecting the angle of attack, the choice of the width of the fourth sealing lip in a transition area adjacent to the base body of the gap seal also influences the ability of the bearing according to the invention to compensate for increases in the sealing gap. A greater width of the fourth sealing lip in this transition area leads to greater stiffness of the fourth sealing lip. Conversely, a smaller width of the fourth sealing lip in this transition area leads to lower stiffness and greater flexibility of the fourth sealing lip. Thus, the width of the fourth sealing lip in the transition area adjacent to the base body of the gap seal is also a design parameter of the gap seal, which influences the sealing effect and the ability of the bearing to compensate for increases in the sealing gap.The seal can be specifically influenced to compensate for sealing gap enlargements that occur during operation.

[0035] Both parameters, i.e., the angle of attack of the fourth sealing lip and the width of the fourth sealing lip in the transition area adjacent to the base body of the gap seal, can be coordinated according to the invention in order to design and optimize the ability of the bearing or the gap seal to compensate for any occurring enlargements of the sealing gap.

[0036] Additionally, the length of the fourth sealing lip is also a parameter that can influence the ability of the bearing or the gap seal to compensate for any increase in the sealing gap.

[0037] All three parameters – angle of attack, width and length of the fourth sealing lip – can be coordinated to achieve an optimized ability of the bearing or gap seal to compensate for any increasing sealing gaps that may occur.

[0038] According to one embodiment of the large-diameter bearing according to the invention, the first bearing ring has a mounting area in a surface region opposite the fourth sealing surface that defines the gap. This mounting area widens the gap. The purpose of this mounting area is to facilitate the correct installation of the gap seal. In particular, the mounting area prevents the fourth sealing lip from being unintentionally and inadvertently pressed into the sliding groove during installation of the gap seal, thus preventing it from bearing against the fourth sealing surface and consequently failing to provide a seal. The mounting area can, for example, be designed as a mounting chamfer formed on the first bearing ring. Alternatively, the mounting area can also be designed as a stepped increase in the inner diameter of the first bearing ring.The assembly area enables reliable, process-safe, positionally correct, simple and effective installation of the gap seal into the large rolling bearing in a defined, stable position in the installation space.

[0039] The mounting area thus prevents impermissible deformation of the fourth sealing lip by pressing the fourth sealing lip against the sealing base body and consequently the impermissible folding of the fourth sealing lip into the sliding groove.

[0040] According to one embodiment of the large rolling bearing according to the invention, the mounting area is designed as a mounting chamfer, through which the width of the gap widens conically, wherein an imaginary extension of the mounting chamfer with a second reference plane parallel to the first reference plane encloses a chamfer angle, and wherein the chamfer angle is greater than or equal to the spreading angle. This ensures reliable assembly of the gap seal.

[0041] The second reference plane can be cylindrical.

[0042] The width of the mounting area should be maximized as much as possible, taking into account strength and installation space limitations. This minimizes the likelihood of the fourth sealing lip unintentionally bearing on the shoulder of the anchoring groove of the sealing foot during installation.

[0043] In one embodiment of the large rolling bearing according to the invention, the fourth sealing lip forms an angle of spread with a third reference plane parallel to the first reference plane, wherein the chamfer angle is greater than or equal to the angle of spread. By selecting the angle of spread, the width of the fourth sealing lip in the transition area adjacent to the base body of the gap seal can be specifically influenced. If the chamfer angle is selected to be greater than or equal to the angle of spread, unwanted bearing of the fourth sealing lip on the mounting area during the installation of the gap seal, and thus undesirable folding of the fourth sealing lip into the sliding groove, is avoided. This ensures reliable installation of the gap seal. This also applies to the so-called "worst case" scenario, i.e.,Even if the gap seal is installed at the most unfavorable angle imaginable, the fourth sealing lip will not be pressed into the sliding groove.

[0044] The third reference plane can be cylindrical.

[0045] According to one embodiment of the large rolling bearing according to the invention, the second bearing ring has a diameter increase in a region between the fourth sealing surface and the sliding groove, thereby reducing the width of the gap. This diameter increase can be formed, for example, by a stepped radius formed on an edge of the second bearing ring, with the edge forming the transition region between the fourth sealing surface and the sliding groove. In addition to this radius, the diameter increase can also have a transition surface extending from the fourth sealing surface towards the radius. The transition surface can be designed as a conical annular surface, but it can also have a different, e.g., non-linear, surface profile.

[0046] This increase in diameter also contributes to the reliable positioning of the fourth sealing lip and supports it under overpressure inside the bearing. During installation of the gap seal, the increased diameter guides the fourth sealing lip into its correct position on the fourth sealing surface and prevents it from folding into the sliding groove during assembly.

[0047] In one embodiment of the large rolling bearing according to the invention, the diameter increase includes a transition surface, wherein the transition surface adjoins the first reference plane and forms a transition angle with the first reference plane. Preferably, the transition angle corresponds to the angle of attack of the fourth sealing lip in the installed position, i.e., the transition angle is the same as the angle of attack of the fourth sealing lip in the installed position. This achieves a positive-locking support of the fourth sealing lip on the second bearing ring. This contributes to a stable installation position of the gap seal even under overpressure inside the bearing.

[0048] According to one embodiment of the large rolling bearing according to the invention, the transition angle is smaller than or equal to the angle of attack. This results in a particularly effective positive-locking support of the fourth sealing lip and a particularly stable installation position of the gap seal under overpressure inside the bearing.

[0049] According to one embodiment of the large rolling bearing according to the invention, the fourth sealing lip has a central axis, wherein the longitudinal extent of the fourth sealing lip extending from a base body of the gap seal and along its central axis has a length, the length being a function of the bearing diameter and being between 1 mm and 12 mm.

[0050] The length L of the fourth sealing lip is a function of the sealing gap change, which in turn is a function of the bearing size / bearing diameter corresponding to the fourth sealing surface, and is between 1 mm (small bearing diameters) and 12 mm (large bearing diameters) depending on the bearing diameter.

[0051] According to one embodiment of the large rolling bearing according to the invention, the width of the fourth sealing lip in the transition area adjacent to the base body of the gap seal is between 0.1 mm and 3 mm.

[0052] According to one embodiment of the large rolling bearing according to the invention, the angle of attack (γ) in the installed state is in a range of 6° ≤ γ ≤ 30°.

[0053] The angle of attack γ is a geometric parameter that describes the angle of the fourth sealing lip relative to the base body. It can differ between the installed and uninstalled state (the so-called sealing profile). Typically, the difference between the angle of attack of the sealing profile and the angle of attack in the installed state is positive, meaning the angle of attack of the fourth sealing lip of the sealing profile is greater than the angle of attack in the installed state.

[0054] Increasing the differential angle by reducing the angle of attack (γ) in the installed state of the gap seal leads to a greater preload of the fourth sealing lip against the fourth sealing surface in the installed state of the gap seal, thus increasing the ability of the fourth sealing lip to compensate for sealing gap enlargements, i.e., with smaller angles of attack (γ) in the installed state, larger sealing gap enlargements can be compensated for without losing the sealing effect of the fourth sealing lip, than is possible with larger angles of attack (γ) in the installed state.

[0055] According to one embodiment of the large rolling bearing according to the invention, the fourth sealing surface is wear-hardened, for example by means of inductive surface hardening. A remaining circumferential area with lower hardness is permissible. The wear-resistant hardening ensures that the sealing effect of the fourth sealing lip is not reduced or even lost due to wear of the fourth sealing surface.

[0056] According to one embodiment of the large rolling bearing according to the invention, the gap seal has a tear-off seal on its outer surface. The tear-off seal has a protective lip designed to prevent the ingress of blasting media from a particle blasting process used for the surface treatment of the first bearing ring into a gap between the first bearing ring and the gap seal. In practice, a surface area of ​​the first bearing ring located near the installed gap seal is often coated using a coating process, for example, zinc flame spraying. To prepare the surface area to be coated, a particle blasting process is used to achieve the desired surface roughness.According to the invention, the protective lip arranged on the tear-off seal prevents the ingress of blasting media used in the particle blasting process into a gap between the first bearing ring and the gap seal. This prevents mechanical damage to the gap seal that could otherwise be caused by particles of the blasting media entering the gap between the first bearing ring and the gap seal.

[0057] According to one embodiment of the invention, the second sealing surface is formed on a boundary surface of the sliding groove located on the outside of the large rolling bearing, and the third sealing surface is formed on a boundary surface of the sliding groove located on the inside of the large rolling bearing. This ensures that, in the event of overpressure inside the bearing, the second sealing lip is pressed axially against a different, radially extending boundary surface of the sliding groove than the third sealing lip. If the overpressure inside the bearing becomes too high, the fourth sealing lip may fail, and the lubricant penetrates the space between the fourth and third sealing lips. If the pressure inside the bearing increases even further, the lubricant penetrates the space between the third and second sealing lips, and the second sealing lip prevents the lubricant from escaping to the outside.At the same time, the pressure in the space between the third and second sealing lips increases when the second sealing lip is pressed against the second sealing surface, and the third sealing lip opens slightly as a result, allowing the lubricant to flow back into the bearing interior.

[0058] According to one embodiment of the invention, the tip of the fourth sealing lip has a rounded reinforcement area that interacts with the fourth sealing surface. This prevents the fourth sealing lip from entering the sliding groove during the installation of the gap seal.

[0059] The invention is explained in more detail below with reference to the figures. Each figure is shown schematically. Fig. 1 a large rolling bearing according to a first embodiment of the invention; Fig. 2 a large rolling bearing according to a second embodiment of the invention; Fig. 3 a large rolling bearing not designed according to the invention with an incorrectly installed gap seal; Fig. 4 an enlarged detail view of the sealing gap area of ​​the large rolling bearing according to the invention according to the first or the second embodiment; Fig. 5 an enlarged detail view of the protective lip of the tear-off seal according to the first or the second embodiment.

[0060] Fig. 1 Figure 1 shows a large rolling bearing designed according to the invention with a gap seal 4 in an installed position according to a first embodiment of the invention. The first bearing ring 1 is designed as the outer ring of the large rolling bearing, while the second bearing ring 2 forms the inner ring of the large rolling bearing. A gap 3 is formed between the first bearing ring 1 and the second bearing ring 2. To prevent lubricant, such as grease, from escaping from the inside of the bearing to the outside A of the large rolling bearing, the gap 3 must be sealed. The gap seal 4 is provided for this purpose.

[0061] The gap seal has a sealing base 5, with which the gap seal 4 is anchored in a circumferential anchoring groove 6 provided in the first bearing ring 1. The sealing base 5 and the anchoring groove 6 can, for example, have positive locking elements with which the sealing base 5 is positively engaged in the anchoring groove 6.

[0062] Furthermore, the gap seal 4 has a first sealing lip 7, a second sealing lip 8, and a third sealing lip 9. The first sealing lip 7 interacts with a first sealing surface 10 formed on the second bearing ring 2. The second sealing lip 8 and the third sealing lip 9 are arranged in a sliding groove 11 formed in the second bearing ring 2. The second sealing lip 8 interacts with a second sealing surface 12, and the third sealing lip 9 interacts with a third sealing surface 13. In the Fig. 1 In the illustrated embodiment, the second sealing surface 12 is formed on a boundary surface of the sliding groove 11 that is associated with the outer surface A of the large rolling bearing. The third sealing surface 13 is formed on a boundary surface of the sliding groove 11 that is associated with the interior of the large rolling bearing.

[0063] Viewed from the outside A of the large slewing bearing, the first sealing surface 10 is arranged axially in front of the second sealing surface 12. The second sealing surface 12 is arranged axially in front of the third sealing surface 13, also viewed from the outside A.

[0064] The sliding groove 11 is located in the Fig. 1 In the illustrated embodiment, the groove is designed as a radial groove extending in the direction R, i.e., the boundary surface of the sliding groove 11 containing the second sealing surface 12 extends in the radial direction R, and the boundary surface of the sliding groove 11 containing the third sealing surface 13 also extends in the radial direction R. However, it would also be conceivable for the boundary surfaces of the sliding groove 11 containing the second sealing surface 12 and the third sealing surface 13 to extend obliquely to the radial direction R. In this case, the boundary surfaces of the sliding groove 11 containing the second sealing surface 12 and the third sealing surface 13 form an angle with the gap 3.

[0065] If, for example, loads from forces and moments acting on the first 1 and second bearing rings 2 during operation of the large rolling bearing cause radial widening of the gap 3, then the second sealing lip 8 can slide along the second sealing surface 12 and the third sealing lip 9 along the third sealing surface 13 without losing the sealing effect of the respective sealing lip. For this reason, the groove in which the second sealing lip 12 and the third sealing lip 13 are arranged when the gap seal 4 is installed is called a "sliding groove".

[0066] The gap seal 4 according to the invention has, in addition to the first, second, and third sealing lips, a fourth sealing lip 14. The fourth sealing lip 14 is arranged in the gap 3 and extends into the gap 3. The fourth sealing lip 14 bears against a fourth sealing surface 15. The fourth sealing surface 15 is formed on the second bearing ring 2 in a section that bounds the gap 3 in the radial direction R. Viewed from the outside A of the large-diameter bearing, the fourth sealing surface 15, which interacts with the fourth sealing lip 14, is arranged axially behind the third sealing surface 13. The fourth sealing surface 15 thus forms the sealing surface that extends axially into the gap 3. Compared to the prior art, the fourth sealing lip 14 and the fourth sealing surface 15 form an additional sealing point, resulting in improved sealing of the large-diameter bearing.

[0067] If there is an overpressure inside the large slewing bearing, the fourth sealing lip 14 is pressed against the fourth sealing surface 15 by the overpressure. In this way, the sealing effect of the fourth sealing lip 14 is further increased by the overpressure. An overpressure inside the bearing can be created, for example, by deliberately generating it through the active introduction of a pressurized gas into the bearing. However, an overpressure inside the bearing can also develop "by itself" during operation of the large slewing bearing. In any case, the large slewing bearing according to the invention is particularly well adapted to such operating conditions with overpressure inside the bearing.

[0068] The invention improves, firstly, the sealing effect, especially in such overpressure operating conditions, and secondly, the invention significantly reduces the risk that the gap seal will be forced out of its installation seat by the internal pressure and that the sealing effect will therefore be lost.

[0069] If the sealing gap widens to such an extent that the fourth sealing lip 14 no longer seals against the fourth sealing surface 15, then, in the gap seal 4 according to the invention, the third and second sealing lips 9 and 8, respectively, are pressed against their respective associated sealing surfaces 13 and 12 in the sliding groove 7 by the overpressure inside the bearing. This continues to prevent the escape of lubricant, in particular grease, even if the fourth sealing lip 14 no longer provides a seal.

[0070] The large rolling bearing according to Fig. 1 The assembly area 16 has a mounting area 16. In the illustrated embodiment, the mounting area 16 is designed as a mounting chamfer 17. According to the invention, instead of a linear mounting chamfer 17 with a constant chamfer angle, other designs of the mounting area 16 are also conceivable, e.g., a stepped profile or a rounded profile formed by a curved section.

[0071] The mounting area is located in a surface area of ​​the gap 3 opposite the fourth sealing surface 14 and defining the gap 3. The mounting area widens the gap 3 in such a way that the surface of the first bearing ring 1, which defines the gap 3, cannot act on the fourth sealing lip 14 during the installation of the gap seal 4 and press it upwards towards the sliding groove 11. This prevents, in particular, the undesired pressing of the fourth sealing lip 14 into the sliding groove 11 (see Figure 1). Fig. 3 ).

[0072] At the in Fig. 1 In the illustrated embodiment of the invention, the second bearing ring 2 has a diameter increase 19 in a region 18 between the fourth sealing surface 14 and the sliding groove 11, which reduces the width of the gap 3. The diameter increase 19 of the second bearing ring 2 projects into the gap 3 and therefore reduces the gap width. The diameter increase 19 prevents the fourth sealing lip 14 from being pressed into the sliding groove 11.

[0073] The in Fig. 1 The depicted diameter increase of 19 is in Fig. 4 shown in an enlarged detail view. The geometry of the diameter enlargement 19 is therefore explained below using the Fig. 4 more precisely described.

[0074] The in Fig. 1 The fourth sealing surface 15 shown is wear-resistant hardened to prevent wear of the sealing surface and thus a decrease in the sealing effect of the fourth sealing lip 14. Wear-resistant hardening can be carried out, for example, by inductive surface hardening.

[0075] Furthermore, in Fig.1 It has been shown that the gap seal 4 has a tear-off seal 22 on its outer surface. The tear-off seal 22 has at least one protective lip 23 that prevents the ingress of blasting media from a particle blasting process used for the surface treatment of the first bearing ring 1 into a gap between the first bearing ring 1 and the gap seal 4. The tear-off seal 22 is arranged on the outer surface of the gap seal 4 and is detachably connected to the gap seal 4.

[0076] In practice, the surface O of the first bearing ring 1, located near the gap, is surface-treated using a particle blasting process to increase the roughness of surface O and thus prepare it for subsequent surface coating (e.g., by zinc flame spraying). To prevent solid particles from penetrating the gap between the first bearing ring 1 and the gap seal 4 during the particle blasting process, a protective lip 23 extends to and rests on a radial surface 24 adjacent to the anchoring groove 6. This prevents the ingress of solid particles into the gap between the first bearing ring 1 and the gap seal 4.The prevention of the penetration of blasting material into this gap is even more effective if the protective lip 23 has a protective lip shoulder 25 at its end which rests on the radial surface 24 and is directed away from the gap 3 in the radial direction R (see detailed illustration according to . Fig. 5 ).

[0077] At the in Fig. 1 In the illustrated embodiment of the invention, the tear-off seal 22 has a second protective lip 23' which extends radially R over the first sealing lip 7. This second protective lip 23' serves to prevent the ingress of blasting media into the space between the second bearing ring 2 and the gap seal 4.

[0078] After completion of the surface treatment using the particle blasting process, the blasting media remaining on the surface of the large slewing bearing is usually removed using compressed air. The tear-off seal 22 can then be torn off and removed from the supporting base body 21 of the gap seal 4. Alternatively, the tear-off seal 22 can also be torn off and removed only after the surface coating following particle blasting (which is carried out, for example, by zinc flame spraying).

[0079] According to one embodiment of the invention, the tip of the fourth sealing lip 14 has – analogous to that in the Fig. 1 bis 3 The tip of the first sealing lip 7, as shown, has a rounded reinforcement area that interacts with the fourth sealing surface 15. This prevents the fourth sealing lip 14 from entering the sliding groove 11 during the installation of the gap seal 4.

[0080] In Fig. 2 A second embodiment of the large-diameter bearing according to the invention is shown. The only difference to the first embodiment according to Fig. 1 The difference is that the first bearing ring 1 is the inner bearing ring and the second bearing ring 2 is the outer bearing ring of the large rolling bearing. Otherwise, the description applies to Fig. 1 also for the embodiment according Fig. 2 .

[0081] The gap seal 4 according to the invention can be used regardless of whether the first bearing ring 1 forms a stationary bearing ring and the second bearing ring 2 a rotating bearing ring, or vice versa.

[0082] The meaning of the term "undesirable pressing of the fourth sealing lip 14 into the sliding groove 11" used in the present description is explained in Fig. 3 This is illustrated using a large rolling bearing not designed according to the invention. The in Fig. 3 The first bearing ring 1 shown has no mounting area 16. The surface of the first bearing ring 1, which defines the gap 3, extends axially to such an extent that it slightly overlaps the sliding groove 11 radially. As a result, during the installation of the gap seal 4, the fourth sealing lip 14 may be pressed into the sliding groove 11 by the material of the first bearing ring 1 located between the anchoring groove 6 and the gap 3. This condition is shown in Fig. 3 The fourth sealing lip 14 then comes into contact with the third sealing surface 13 within the sliding groove 11 in this state. When this occurs, the sealing effect of the fourth sealing lip 14 is no longer present. An increased internal bearing pressure then no longer leads to the fourth sealing lip 14 being pressed against the fourth sealing surface 15 on the second bearing ring 2 and thus to an increase in the sealing effect (as shown in Fig. 1 and 2), but to a reduction in the sealing effect, because the fourth sealing lip 14 is pushed away from the third sealing surface 13 by the increased internal bearing pressure.

[0083] In Fig. 4 The gap seal 4 is shown in an enlarged view in its installed position. The fourth sealing lip 14 projects into the gap 3 between the first bearing ring 1 and the second bearing ring 2. The fourth sealing lip 14 bears against the fourth sealing surface 15, which is formed on a surface area of ​​the second bearing ring 2 that defines the gap 3. The fourth sealing surface 15 is wear-hardened. The fourth sealing lip 14 has an angle of attack γ. The angle of attack γ is defined by the surface of the fourth sealing lip 14 facing the second bearing ring 2 and the first reference plane E1. In the illustrated embodiment, the angle of attack γ is between 6° and 30°. Furthermore, the fourth sealing lip 14 has a spreading angle β, which is between 6° and 30°.The spreading angle β is enclosed by the surface of the fourth sealing lip 14 facing the first bearing ring 1 and a third reference plane E3, wherein the third reference plane E3 runs parallel to the first reference plane E1.

[0084] Furthermore, a mounting area 16 is provided on the first bearing ring 1, which is designed as a mounting chamfer 17. The mounting chamfer 17 has a chamfer angle α. In the illustrated embodiment, the chamfer angle α is equal to the offset angle β. The chamfer angle α is enclosed by the surface of the mounting area 16 or the mounting chamfer 17 and a second reference plane E2. In the illustrated embodiment, the second reference plane E2 is arranged parallel to the third reference plane E3 and the first reference plane E1.

[0085] The second bearing ring 2 has a diameter increase 19 in the transition area between the fourth sealing surface 15 and the sliding groove 11. The diameter increase comprises a transition surface 20 and a molded radius, which is formed on an edge of the second bearing ring 2 in the transition area from the surface defining the gap 3 to the third sealing surface 13 of the sliding groove 11. In the illustrated embodiment, the transition surface 20 is designed as a conical annular surface. It adjoins the first reference plane E1 and forms a transition angle δ with it. In the illustrated embodiment, the transition angle δ is equal to the angle of attack γ of the fourth sealing lip 14.

[0086] The increased diameter provides positive support for the fourth sealing lip 14 when it is pressed against the second bearing ring 2 due to increased internal bearing pressure. This contributes to a stable position of the gap seal 4 in the gap 3. Furthermore, the increased diameter helps to prevent the fourth sealing lip 14 from being forced into the sliding groove 11, which can occur particularly during the installation of the gap seal 4.

[0087] In the illustrated embodiment, the transition surface 20, designed as a conical annular surface, serves as an insertion chamfer for the fourth sealing lip 14 during the assembly of the gap seal. The transition surface 20 thus ensures the secure assembly of the gap seal 4 and prevents the fourth sealing lip 14 from "folding in" into the sliding groove 11.

[0088] Furthermore, the transition surface 20 increases the sealing effect when the sealing gap widens, because when the sealing gap widens, the contact point of the fourth sealing lip 14 with the second bearing ring 2 shifts into the area of ​​the transition surface 20. This leads to an increased contact pressure of the fourth sealing lip 14 and thus to an increase in the sealing effect.

[0089] Furthermore, the transition surface 20 has the effect that an increased internal pressure in the bearing leads to additional support of the fourth sealing surface 14 on the transition surface 20 through deformation of the fourth sealing lip 14. This additional support on the transition surface 20 results in increased sealing and reduced mechanical stress on the fourth sealing lip 14.

[0090] The fourth sealing lip 14 has a center line. The longitudinal extent of the fourth sealing lip 14, extending from the base body 21 of the gap seal 4, has a length L along the center line. The length L of the fourth sealing lip 14 is a function of the bearing diameter and is between 1 mm and 12 mm.

[0091] Fig. 5 Figure 1 shows an enlarged detail view of the protective lip 23 arranged on the tear-off seal 22. The protective lip 23 prevents solid particles from penetrating into a gap between the first bearing ring 1 and the gap seal 4 during a particle blasting process. The protective lip 23 extends from the tear-off seal 22 down to a point where it meets the (in Fig. 5The anchoring groove 6 (not shown) is adjacent to the radial surface 24 and rests on it. This prevents the ingress of solid particles into the space between the first bearing ring 1 and the gap seal 4. The protective lip 23 has a protective lip shoulder 25 at its end, which rests on the radial surface 24 and is directed radially R away from the gap 3. This further prevents the ingress of blasting media into the space between the first bearing ring 1 and the gap seal 4. Reference symbol list

[0092] 1 Bearing ring 2 Bearing ring 3 Gap 4 Gap seal 5 Sealing base 6 Anchoring groove 7 First sealing lip 8 Second sealing lip 9 Third sealing lip 10 First sealing surface 11 Sliding groove 12 Second sealing surface 13 Third sealing surface 14 Fourth sealing lip 15 Fourth sealing surface 16 Mounting area 17 Mounting chamfer 18 Area 19 Diameter increase 20 Transition surface 21 Base body 22 Tear-off seal 23 Protective lip 24 Radial surface A Outer side E1 First reference plane E2 Second reference plane E3 Third reference plane α Chamfer angle β Spread angle γ Angle of attack δ Transition angle L Length D Bearing race diameter R Radial direction

Claims

1. Large-diameter roller bearing with a first bearing ring (1), a second bearing ring (2), and a gap (3) between the first (1) and second bearing rings (2), wherein an annular gap seal (4) is arranged in the gap (3) to prevent lubricant from escaping from the interior of the large-diameter roller bearing to the outside, wherein the gap seal (4) has a sealing foot (5) which is received in an anchoring groove (6) provided in the first bearing ring (1), wherein the gap seal (4) has a first sealing lip (7), a second sealing lip (8), and a third sealing lip (9), wherein the first sealing lip (7) is supported against a first sealing surface (10) formed on the second bearing ring (2), wherein the second (8) and third sealing lips (9) are received in a sliding groove (11) arranged in the second bearing ring (2) in such a way that the second sealing lip (8) bears against a second sealing surface (12) delimiting the sliding groove (11) and the third sealing lip (9) bears against a third sealing surface (13) delimiting the sliding groove (11), wherein, viewed from an outer side (A) of the large-diameter roller bearing, the first sealing surface (10) is arranged in front of the second sealing surface (12) and the second sealing surface (12) is arranged in front of the third sealing surface (13), wherein the gap seal (4) has a fourth sealing lip (14) arranged in the gap (3), which extends into the gap (3) and is supported against a fourth sealing surface (15), wherein the fourth sealing surface (15) is formed on a section of the second bearing ring (2) which delimits the gap (3) in the radial direction, and wherein the fourth sealing surface (15) is arranged behind the third sealing surface (13) as viewed from the outside (A) of the large-diameter roller bearing, characterized in that the first (7), second (8) and third sealing lips (9) assume a defined, stable position in the installation space when there is excess pressure inside the bearing, and that the axial second sealing lip (8) is pressed onto the second sealing surface (12) and the axial third sealing lip (9) is pressed onto the third sealing surface (13) by the excess pressure.

2. Large-diameter roller bearing according to claim 1, wherein the fourth sealing lip (14) encloses an angle of attack (γ) with a first reference plane (E1) containing the fourth sealing surface (15), wherein the fourth sealing lip (14) has a width (B) in a transition area adjacent to a base body (21) of the gap seal (4), wherein the ability of the bearing to compensate for an increase in the sealing gap can be adjusted by selecting the angle of attack (γ) and the width (B) as well as a length (L) of the fourth sealing lip (14) perpendicular to the width.

3. Large-diameter roller bearing according to claim 1 or 2, wherein the first bearing ring (1) has a mounting area (16) in a surface area opposite the fourth sealing surface (15) and bordering the gap (3), through which the width of the gap (3) is widened.

4. Large-diameter roller bearing according to claim 3, wherein the mounting area (16) is designed as a mounting chamfer (17) through which the width of the gap (3) widens conically, wherein an imaginary extension of the mounting chamfer (17) encloses a chamfer angle (α) with a second reference plane (E2) parallel to the first reference plane (E1).

5. Large-diameter roller bearing according to claim 4, wherein the fourth sealing lip (14) encloses a spread angle (β) with a third reference plane (E3) parallel to the first reference plane (E1), and wherein the chamfer angle (α) is greater than or equal to the spread angle (β).

6. Large-diameter roller bearing according to one of the preceding claims, wherein the second bearing ring (2) has a diameter enlargement (19) in a region (18) between the fourth sealing surface (15) and the sliding groove (11), which reduces the width of the gap (3).

7. Large-diameter roller bearing according to claim 6, wherein the diameter enlargement (19) comprises a transition surface (20), wherein the transition surface (20) adjoins the first reference plane (E1), wherein the transition surface (20) encloses a transition angle (δ) with the first reference plane (E1).

8. Large-diameter roller bearing according to claim 7, wherein the transition angle (δ) is smaller than or equal to the angle of attack (γ).

9. Large-diameter roller bearing according to one of the preceding claims, wherein the fourth sealing lip (14) has a center axis, wherein a longitudinal extension of the fourth sealing lip (14) starting from a base body (21) of the gap seal (4) and extending along its center axis has a length / L), wherein the length (L) is a function of the bearing diameter and is between 1 mm and 12 mm.

10. Large-diameter roller bearing according to one of claims 2 to 9, wherein the width (B) of the fourth sealing lip (14) in the transition area adjacent to the base body (21) of the gap seal (4) is between 0.1 mm and 3 mm.

11. Large-diameter roller bearing according to one of claims 2 to 10, wherein the angle of attack (γ) is in a range of 6° ≤ γ ≤ 30°.

12. Large-diameter roller bearing according to one of the preceding claims, wherein the fourth sealing surface (15) is wear-hardened.

13. Large-diameter roller bearing according to one of the preceding claims, wherein the gap seal (4) has a tear-off seal (22) on its outer side, wherein the tear-off seal (22) has at least one protective lip (23) which is designed to prevent the penetration of blasting material from a particle blasting process used for surface treatment of the first bearing ring (1) into a space between the first bearing ring (1) and the gap seal (4).

14. Large-diameter roller bearing according to one of the preceding claims, wherein the second sealing surface (12) is formed on a boundary surface of the sliding groove (11) associated with the outer side (A) of the large-diameter roller bearing (11) and the third sealing surface (13) is formed on a boundary surface of the sliding groove (11) associated with the interior of the large-diameter roller bearing.

15. Large-diameter roller bearing according to one of the preceding claims, wherein the tip of the fourth sealing lip (14) has a rounded reinforcement area that interacts with the fourth sealing surface (15).