WO2019137572A1

WO2019137572A1 - Wheel bearing for a motor vehicle wheel

Info

Publication number: WO2019137572A1
Application number: PCT/DE2018/100918
Authority: WO
Inventors: Marc-André SCHÄFER
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2018-01-15
Filing date: 2018-11-13
Publication date: 2019-07-18
Also published as: DE102018100750A1; DE102018100750B4

Abstract

A wheel bearing (12) for mounting a motor vehicle tyre of a motor vehicle is provided with a first ring (14), a second ring (20) which is mounted such that it can be rotated relative to the first ring (14), a sealing partner (50) which is fastened fixedly to the second ring (20) so as to rotate with it, a further sealing partner (50) which is fastened fixedly to the second ring (20) so as to rotate with it, a pressure chamber (36) which is configured in the radial direction between the first ring (14) and the second ring (20) and in the axial direction between the sealing partner (50) and the further sealing partner (50), a seal unit (38) which delimits the pressure chamber (36) on a first axial side in order to produce a sealing contact with the sealing partner (50), a further seal unit (60) which delimits the pressure chamber (36) on a second axial side in order to produce a sealing contact with the further sealing partner (50), and a seal holder (26) which delimits the pressure chamber (36) on a radial circumferential surface which points away from the first ring (14), wherein the seal holder (26) presses the seal unit (38) and the further seal unit (60) sealingly toward a circumferential surface of the first ring (14), wherein the first ring (14) has an inlet (16) which can communicate with the pressure chamber (36), wherein the seal holder (26) has an outlet channel (54) which can communicate with the pressure chamber (36) and with an outlet (22) which is configured in the second ring (20), wherein the flow cross section of the outlet channel (54) is dimensioned, in the case of a delivery of a pressure fluid from a pressure source which bears against the inlet (16) to a pressure use chamber which bears against the outlet (22), in particular a tyre tube of a motor vehicle tyre, so as to bring about a back pressure in the pressure chamber (36) in order to press the seal unit (38) sealingly against the sealing partner (50) and so as to press the further seal unit (60) sealingly against the further sealing partner (50). As a result, an inexpensive rotary leadthrough for a wheel bearing (12) is made possible.

Description

WHEEL BEARINGS FOR A MOTORCYCLE WHEEL

The invention relates to wheel bearings for mounting a motor vehicle tire of a motor vehicle, with the aid of which a rotary feedthrough can be formed in the wheel bearing in order to pass a pressurized fluid through the wheel bearing in the radial direction, in particular to set a tire pressure of a tire of the motor vehicle.

The tires of motor vehicles have different, optimal tire pressure depending on the surface and load. For example, on loose ground,

Sand, mud or similar requires the best possible traction, which can be achieved with a tire with a very low tire pressure. On a level surface such as a country lane, sufficient traction is achieved even with higher tire pressure, with a tire with high tire pressure resulting in less friction and lower fuel consumption. For a fully loaded truck, the optimum tire pressure is higher than for a full-load truck. Trucks that drive in the field or on construction sites, such as a tipper, are usually either completely empty or completely loaded on the way, so that especially for such trucks, the difference between the optimal tire pressures is particularly large.

From DE 10 2015 212 641 A1 a sealing arrangement for a wheel bearing of a motor vehicle is known in which the sealing arrangement has a limited by axially displaceable re sealing elements pressure chamber for passage of compressed air in the radial direction, wherein the sealing elements by the pressure of the compressed air against each a relatively rotatable ring member of the wheel bearing are pressed to make a sealing contact. With the aid of such a wheel bearing, a pneumatic system provided in the motor vehicle can adapt the tire pressure of the motor vehicle to the optimum tire pressure in the current situation.

There is a constant need to reduce the manufacturing cost of a rotary feedthrough of a wheel bearing. It is the object of the invention to show measures that allow a cost rotary feedthrough for a wheel bearing.

The object is achieved according to the invention by a wheel bearing having the features of claim 1. Preferred embodiments of the invention are specified in the subclaims and the following description, which individually or in combination may represent an aspect of the invention.

According to the invention, a wheel bearing for mounting a motor vehicle tire of a motor vehicle, in particular truck, provided with a, designed in particular as an inner bearing ring, a first ring, in particular designed as Außenlager- ring or hub, rotatably mounted relative to the first ring second ring, a rotationally fixed with the second ring directly or indirectly fastened sealing partner, a rotationally fixed to the second ring directly or indirectly attached further sealing partner, a radially formed between the first ring and the second ring and in the axial direction between the sealing partner and the other sealing partner formed pressure chamber a sealing unit delimiting the pressure chamber at a first axial side and axially displaceable as a result of a pressure in the pressure chamber and / or axially elastically deformable for producing a sealing contact with the sealing partner, one the pressure chamber at one of the first A xialseite different second axial side limiting and axially displaceable as a result of pressure applied in the pressure chamber and / or axially elastically deformable further seal unit for producing a sealing contact with the other sealing partner and the pressure chamber at a side facing away from the first ring radial lateral surface sealing seal holder, wherein the The seal holder sealingly presses the seal unit and the further seal unit onto a lateral surface of the first ring, the first ring having an inlet communicable with the pressure chamber, the seal holder communicating with the pressure chamber and with an outlet formed in the second ring having a scalable outlet channel, wherein the flow cross-section of the outlet channel is dimensioned when a pressure fluid is conveyed from a pressure source which adjoins the inlet to a pressure space which adjoins the outlet, in particular special tire hose of a motor vehicle tire, to bring about a back pressure in the pressure chamber for sealingly pressing the sealing unit against the sealing partner and for sealingly pressing the further sealing unit against the further sealing partner.

The seal holder can rotate with the rotational speed of the first ring, for which purpose the seal holder can be non-rotatably coupled to the first ring, for example via a sealing frictional connection of the sealing units with the first ring, while the sealing partners are non-rotatably connected to the second ring. The seal holder and the sealing units can be coupled to an inner bearing ring of the wheel bearing, while the sealing partners are coupled to an outer bearing ring or a hub of the wheel bearing, or vice versa. The sealing contact of the respective sealing unit on the associated sealing partner can seal the inner ring against the outer ring. A relative rotation can take place during operation between the sealing unit and the sealing partner, which can lead to abrasive wear and / or wear caused by thermal stress, in particular in the case of the sealing unit at the contact point with the sealing partner. Due to the relative movability of the seal unit to the seal holder in the axial direction, the seal unit can adjust the wear by further shifting the seal unit axially by the extent of the wear on the sealing partner and / or deformed. Since the sealing unit delimits a part of the pressure chamber, the pressure of the pressure fluid, in particular compressed air, can abut on a rear side of the sealing unit pointing toward the pressure chamber and away from the sealing partner, so that the pressure of the pressure fluid itself is the sealing unit for adjusting the wear-related axial Spacing can shift axially. A leakage of the pressure fluid caused by wear effects of the sealing unit at the sealing contact point between the sealing unit and the sealing partner can thereby be avoided. Since the essentially annular sealing unit presses against the sealing partner on its axial side, in the case of abrasive wear, only an axial offset of the sealing unit is sufficient to readjust the wear. In particular, it avoids thereby widening an annular component for wear adjustment. This allows it To provide the sealing contact point particularly wear-resistant materials, which usually have a poor elasticity and can hardly be widened. Instead of a lateral surface facing in the radial direction, an end face of the annular sealing unit pointing in the axial direction can be pressed on. In comparison to a sealing unit acting in the radial direction, a lower wear can be achieved thereby. The at least one material used for the sealing unit is in particular heat-resistant up to a temperature of for example 260 ° C. In particular, the material has a ductility which is sufficient to be insensitive to shocks expected during operation. For example, the respective material has an elongation of 5% to 10%. The thermal expansion coefficient of the respective material corresponds in particular essentially to the thermal expansion coefficient of the material used for the bearing rings of the wheel bearing, in particular steel.

If a pressure in the pressure space is to be increased, additional, in particular compressible, pressurized fluid can be supplied via the inlet. However, this pressure fluid is initially jammed in the pressure chamber by the outlet channel. For this purpose, for example, the flow cross section of the outlet channel is correspondingly smaller than the flow cross section of the inlet. If several outlet channels are provided for the same pressure chamber, the sum of the flow cross sections of all outlet channels applies to this comparison. If several inlets are provided for the same pressure chamber, the sum of the flow cross sections of all inlets is valid for this comparison. The outlet channel or the sum of several outlet channels can act as a throttle, which only allows a time-delayed compensation of the pressure in front of and behind the outlet channel. Before the pressure fluid can reach the sealing contact point between the sealing unit and the sealing partner, the pressure fluid is retained in the pressure chamber, whereby the pressure in the pressure chamber increases. The outlet channel, in the manner of a throttle when filling the pressure working space, can accumulate the pressure fluid in the pressure chamber and generate a back pressure. The kinetic energy of the pressure fluid is converted by the throttling action of the outlet channel into an increase of the static pressure in the pressure chamber, whereby possibly the density of the pressure fluid in the pressure fluid Can increase pressure chamber. The increased pressure in the pressure chamber leads to a greater contact pressure of the sealing unit on the sealing partner, which increases the sealing effect. When the pressure fluid finally leaves the pressure chamber via the outlet channel and also reaches the sealing contact point between the sealing unit and the sealing partner, a sealing effect sufficient for the increased pressure already exists at the sealing contact point, so that the early attainment of the sealing effect for the increased pressure required sealing effect, before the increased pressure at the sealing contact point is constructed, leakage can be avoided. Since the sealing unit limits a part of the pressure chamber, the premature increase of the sealing effect can be effected automatically by the pressure applied to the inlet. If a pressure in the pressure space is to be reduced, the pressure applied by the pressure source at the inlet can be reduced. This also reduces the pressure in the pressure chamber accordingly. Due to the throttling effect of the outlet channel, the pressure fluid present in the pressure space is initially retained somewhat, so that initially a lower pressure is established in the pressure chamber than in the pressure space over a certain period of time. As a result, the contact pressure of the sealing unit on the sealing partner can be reduced rapidly, thereby avoiding unnecessary wear.

Since the pressure fluid preferably flows through the outlet channel, the portions of the pressure fluid present at the sealing contact point can be sucked off or entrained in the manner of an ejector pump, so that premature reduction of the contact force of the sealing unit does not lead to leakage or at least only to a low, especially negligible, leakage leads. Due to the throttling effect of the outlet channel, the sealing effect of the sealing unit can be adjusted in advance to a changing setpoint pressure via the pressure setting in the pressure chamber, so that a rotary feedthrough for a wheel bearing with a small amount of wear occurs due to the sealing arrangement with little wear Leakage is possible.

The seal holder may be designed substantially annular. The sealing units are arranged in the radial direction between the seal holder and the first ring. The sealing units can with the first ring on the one hand and with the seal holder on the other hand a fit, especially light

Press fit, training. In particular, the sealing units lie at least partially in the radial direction directly on the first ring and / or directly on the seal holder. The pressure chamber is thereby adequately sealed between the sealing units and the first ring on the one hand and between the sealing units and the seal holder on the other hand. At the same time, the fits can permit an axial displacement and / or an elastic deformation in the axial direction of the sealing units, so that a sufficient sealing effect between the sealing units and the associated sealing partners is not impaired. Particularly preferably, the sealing units have a flexible, in particular elastomeric, material, at least at the jacket sides facing the first ring and the seal holder, so that the sealing contact of the sealing units with the first ring and with the seal holder is achieved by an elastic deformation of the seal. processing units may even increase at a pressure rising in the pressure chamber. If the pressure in the pressure chamber increases, first the sealing units can be displaced in the axial direction and / or elastically deformed until a sufficient sealing contact with the associated sealing partner is established. In this position, a further axial displacement and / or deformation is blocked by the sealing partner, so that the material of the sealing unit can deflect elastically only in the radial direction due to the applied pressure in the pressure chamber, resulting in a sufficient sealing of the pressure chamber between the Seal units and the first ring and between the seal units and the seal holder results. A retaining ring connected to the seal holder and arranged between the sealing units and the first ring for holding the sealing units can be omitted here. As a result, a separate seal between the seal holder and the first ring, or between the holder ring and the first ring, can be saved. The structure of the retaining ring can be simplified, so that the retaining ring can be made easier and cheaper. In addition, the number of components and thus the manufacturing costs can be reduced and the assembly can be simplified by the seal saved between the holder ring and the first ring. Due to the additional sealing of the seal achieved with the aid of the seal holder Processing units on the first ring, the number of components and the structural complexity of the retaining ring can be reduced, so that a cost-rotary connection is made possible for a wheel bearing.

The seal holder, the sealing unit and the further sealing unit can together form a sealing arrangement, which can be installed in particular as a common preassembled unit in the wheel bearing. The first ring and the second ring can form at least one roller bearing with the aid of rolling elements arranged between the first ring and the second ring. The wheel bearing can also be used outside of an application as a wheel bearing for a tire of a motor vehicle for various applications. For many applications, it is sufficient if the inner diameter of one of the rolling bearings of the at least two-row wheel bearing or single-row wheel bearing between 50 mm inclusive and 160 mm including, in particular, the outer diameter of the bearing between 90 mm and including 230 mm. Preferably, the axial width of the rolling bearing is between 81 mm and 116 mm inclusive. As a result, the radial extent of the wheel bearing is large enough to accommodate the sealing arrangement and to be able to manufacture and assemble the sealing arrangement cost-effectively. If a common bearing ring is used for the two rolling bearings, which accommodates in particular the seal holder of the sealing arrangement, a correspondingly twice as large axial width can be provided for the bearing ring provided for both rolling bearings. For ease of assembly, the bearing ring may have a slightly larger axial dimension, for example, between 165 mm and 250 mm inclusive.

If the wheel bearing is configured as a double-row wheel bearing, it is possible for the sealing unit to seal off a rolling bearing and the further sealing unit seals against the other rolling bearing of the double-row wheel bearing. The sealing unit and the further sealing unit can be accommodated axially between the two separate roller bearings of the double-row wheel bearing with the least possible clearance of, for example, 200 μm by axial stops of the roller bearings. In particular, the rolling bearings are designed as angular contact ball bearings and / or tapered roller bearings. As a result, the bearing rings, which essentially clamp and / or axially fix the sealing arrangement, can be pressed towards one another during operation and automatically clamp and / or axially fix the sealing arrangement substantially free from play.

In particular, the seal holder has a first axial stop for retaining the sealing unit in the pressure chamber and / or a further first axial stop for retaining the further sealing unit in the pressure chamber. An axial falling out of the sealing units from the seal holder can be avoided. When the seal units are inserted in the seal retainer, the seal units can be elastically compressed to move past the respective axial stopper of the seal retainer. Within the seal holder, the sealing unit can elastically expand to the essentially original radial extension, so that the first axial stop can engage behind the sealing unit axially on the outside. The seal units which are thereby captively inserted in the seal holder can form a common preassembled structural unit with the seal holder, which can be installed easily and inexpensively during installation in the wheel bearing. In addition, the seal holder can be automatically centered on the sealing units in the axial direction, so that the same contact pressure automatically bears against the respective sealing partner of both seal units.

The seal holder preferably has a second axial stop for abutment of a rear side of the seal unit facing away from the seal partner and / or a further second axial stop for abutment of a rear side of the further seal unit pointing away from the further seal partner. The sealing units can thereby be kept at a defined minimum distance. As a result, a corresponding minimum width in the axial direction is predetermined for the pressure chamber. The second axial stops can block an excessive axial displacement of the respective sealing unit to the center of the seal holder, so that it can be avoided that the sealing unit covers the inlet of the first ring and accidentally closes. The functionality of the Seal assembly trained rotary feedthrough is ensured. In addition, the seal holder can be automatically centered on the seal units in the axial direction, so that automatically applied by both seal units, the same contact pressure on the respective sealing partner.

Particularly preferably, a spacer ring arranged between the seal unit and the further seal unit is provided on a jacket surface of the first seal facing the pressure chamber, the spacer ring sealingly abutting the seal unit and the further seal unit in the radial direction and an inlet channel communicable with the inlet In particular, the flow cross-section of the inlet channel is at least as large as the flow cross-section of the inlet. The spacer ring can have a second axial stop for stopping a rear side of the sealing unit facing away from the sealing partner and / or a further second axial stop for striking a rear side of the further sealing unit pointing away from the further sealing partner. The sealing units can be kept at a defined minimum distance. As a result, a corresponding minimum width in the axial direction is predetermined for the pressure chamber. The second axial stops can block an excessive axial displacement of the respective sealing unit to the center of the seal holder, so that it can be avoided that the sealing unit covers the inlet of the first ring and accidentally closes. The functionality of the rotary feedthrough formed by the sealing arrangement is thereby ensured. In this case, the inlet channel of the spacer ring is in particular dimensioned such that, taking into account tolerances, the spacer ring does not cover a part of the flow cross-section of the inlet. Particularly preferably, the sealing units are additionally or alternatively pressed against the first ring by the seal holder pressing against the first ring against the spacer ring, in particular in order to seal the pressure chamber. The spacer ring preferably has a peripheral surface facing the sealing units, which allows a better sealing effect in comparison with the lateral surface facing the sealing units from the first ring. Due to the radial extension of the spacer ring, the radial extent of the pressure chamber can be reduced and the axial surface of the rear side of the respective sealing unit facing the pressure chamber can be correspondingly reduced, so that the contact pressure of the sealing units on the respective sealing partner can be reduced to a required extent.

In particular, a further rotatably mounted relative to the second ring and separate from the first ring further first ring is provided, wherein the first ring and the other first ring viewed in the radial direction each cover a portion of the pressure chamber, wherein the inlet either only in the first ring or only is provided in the further first ring. The first ring and the second ring may in particular each be a bearing ring of two different roller bearings, so that the wheel bearing is designed as a minimum of two-row wheel bearing. Since the inlet is provided only in one of the first rings, a machining operation to produce the inlet is required only on this first ring. The other first ring, in which the inlet is not provided, need not be processed, so that the manufacturing cost can be reduced.

Preferably, the inlet is positioned spaced from a contact point between the first ring and the further first ring in the axial direction. The inlet does not need to be provided at the axial end face of the first ring. Instead, the inlet can be provided offset axially to this end face. The inlet can be made easily and inexpensively by drilling. Sharp edges in the axial end face can be avoided.

Particularly preferably, the inlet is positioned in the axial direction off-center to the pressure chamber and / or to the seal holder. In principle, it is possible to provide different axial extensions for the first ring and the further first ring, so that the inlet provided in only one of the first rings is positioned substantially centrally of the seal holder. With a sufficient axial extent of the pressure chamber, however, the axial extent may be sufficient for a connection of the inlet to the pressure chamber, in particular over an off-center positioning of the inlet relative to the seal holder the full flow cross-section of the inlet can be formed. This makes it possible to produce the first ring and the other first ring as equal parts, of which only one is provided with the inlet. The manufacturing costs can be reduced.

In particular, a spacer ring arranged between the sealing unit and the further sealing unit is provided on a lateral surface of the first ring and the further first sealing ring facing the pressure chamber, the spacer ring having an inlet channel communicable with the inlet, the spacer ring being connected to both the first ring and the first annular ring is also connected to the other first ring, in particular in order to press the first ring and the other first ring in the axial direction to each other. The spacer ring can in particular be designed and developed as described above. The spacer ring can thereby not only keep the sealing units at a defined minimum distance and / or keep the sealing units away from the inlet, but also connect the first ring to the further first ring. The rotational feedthrough provided between two rolling bearings of the wheel bearing can also form a connecting means with the aid of the sealing arrangement via the spacer ring, as a result of which a further functionality is integrated in the sealing arrangement.

Preferably, the spacer ring engages with a retaining hook and / or a retaining collar in the inlet. The inlet may provide a recess in the first ring into which the spacer ring may be inserted, in particular hooked, to impart a force in the axial direction by means of which the first ring may be drawn towards the further first ring ,

Particularly preferably, the spacer ring is fastened to the first ring and / or to the further first ring by means of a latching nose guided resiliently past at least one latching catch. The spacer ring can, similar to a cable tie, upon an axial approach of the first ring to the further first ring, move a latching lug past a particular ramped latching intersection, so that the pawls which are retracted after passing the latching intersection derte latching nose can engage behind the latching intersection captive. Preferably, the spacer ring is made of a plastic material, so that in particular the spacer ring can form the resilient latching lug. In particular, the first ring and / or the further first ring can have a plurality of grooves, grooves, notches and / or grooves, which can fill out the function of the snap-in intersection.

In particular, the sealing unit and / or the further sealing unit has a support ring arranged substantially coaxially with the axis of rotation of the wheel bearing for abrading axial forces and / or a collar arranged substantially coaxially with the axis of rotation of the wheel bearing, directly on the respective one Sealing partner rests on sealing ring for providing a sealing contact with the sealing partner by an elastic deformation. The support ring and / or the sealing ring can be used in particular in a, preferably made of an elastomeric material, retaining ring of the sealing unit. The retaining ring can be elastically deformed, for example, by the pressure applied in the pressure chamber and press the support ring and / or the sealing ring against the sealing partner, while the support ring and / or the sealing ring can be made of a different material. In particular, the support ring is made of a particularly pressure-resistant and / or wear-resistant material. For example, the support ring is made of a polyamide-imide (PAI), which may have an increased graphite content for improved wear resistance. The sealing ring can be particularly soft and thereby achieve a particularly good seal. The sealing ring is made of polytetrafluoroethylene (PTFE), for example. The support ring can remove a large part of the contact forces, so that lower forces act on the sealing ring and the material of the sealing ring, which is softer compared to the support ring, does not wear out so easily. When the retaining ring is made of an elastomeric material, the sealing unit during assembly can be easily pressed through a sealing partner facing the tapered opening of the seal holder to hold the seal unit captive in the seal holder until the assembly of the sealing partner. Alternatively, the sealing partner facing the opening of the seal holder in the radial direction be as large as the radial extent of the sealing unit, in particular between the seal holder and the Gasket unit is formed a clearance, which allows easy axial displaceability of the sealing unit in the seal holder.

Preferably, the support ring and the sealing ring are in a substantially coaxial to the axis of rotation of the wheel bearing arranged retaining ring spaced from each other in the radial direction or added to each other in the radial direction. If the support ring and the sealing ring are arranged spaced from one another, these rings can each be accommodated separately in a separate receiving pocket of the retaining ring of the sealing unit. The individual rings are thereby decoupled from each other and separated, so that a gene-side blocking is avoided. This can allow a particularly low wear and a long service life even with an unlubricated sealing contact point. In particular, when the sealing contact point is lubricated, the rings can be accommodated against one another in a common receiving pocket of the retaining ring. As a result, space is created in the radial direction in the area of the sealing contact point, in which at least one further supporting ring and / or sealing ring can be provided. In particular, the at least one support ring and the at least one sealing ring are arranged in an alternating manner. The surface for the sealing contact between the sealing unit and the sealing partner can thereby be increased, whereby a higher sealing effect can be achieved with lower required contact forces. This allows for a low wear a high sealing effect.

Particularly preferably, a relief groove is formed between the retaining ring, in particular made of an elastomeric material, on the one hand, and the support ring and / or the sealing ring, on the other hand. By means of the relief groove, for example, the support ring and / or the sealing ring can tilt slightly within the holding pocket of the holding ring, as a result of which the supporting ring and / or the sealing ring can automatically align automatically with the sealing partner, even in the event of uneven wear. In addition, the retaining ring can escape in an elastic deformation by the pressure applied in the pressure chamber in the relief groove, so that a blocking of the sealing unit can be avoided within the seal holder. In particular, the support ring and / or the sealing ring is received in an elastic receiving pocket of the sealing unit. Even if the retaining ring of the sealing unit should not be made of an elastomeric material, at least the receiving pocket can yield elastically, for example by elastically deforming an elastomeric inner coating of the receiving pocket. By means of the elastic receiving pocket, for example, the support ring and / or the sealing ring can tilt slightly within the receiving pocket of the retaining ring, as a result of which the supporting ring and / or the sealing ring can align automatically with the sealing partner even if the wear is uneven. Unnecessary wear is thereby avoided.

The sealing unit and / or the further sealing unit preferably forms a counterpressure gap between a part of the sealing unit and the sealing partner in the state pressed against the associated sealing partner, the counterpressure gap, in particular downstream of the outlet channel, communicating with the outlet channel and / or with the outlet channel Print room communicates. At least in the region of the counter-pressure gap, a concern of the sealing unit on the sealing partner is not provided. This makes it possible for the pressurized fluid to reach the counter-pressure gap and to impart a force of the sealing unit opposite to the pressing-on direction of the sealing unit to the sealing partner. The contact pressure can thereby be reduced, in particular to the required minimum, so that wear due to an unnecessarily high contact pressure can be avoided. If the pressure in the pressure working space is to be increased, the sealing unit can be pressed against the sealing partner at an optionally slightly too high pressure, so that a pressure equalization between the pressure provided by the pressure source and the pressure in the pressure space is sufficient during the period until Essentially leak-free sealing is provided. Due to the gradual build-up of pressure in the

Pressure space is built downstream of the outlet channel and the pressure in the counter-pressure gap, whereby the contact pressure can be reduced to a lower but sufficient pressure. To set a desired pressing force in the stationary state, the area of the pressure in the counter-pressure gap to the sealing partner facing the front of the sealing unit depending on the surface of the pressure chamber delimiting the rear side of the seal unit are selected so that the desired contact force results as a resultant force acting on the seal unit and opposing directions of pressure in the pressure chamber and in the counter-pressure gap. The time delay during the buildup of pressure in the counter-pressure gap achieved with the aid of the throttling action of the outlet channel prevents leaks in the unsteady phase of the pressure increase due to pressure fluctuations in the pressure applied by the pressure source, which lead to a leakage of pressurized fluid can. In addition, it is possible to provide a further counter-pressure gap which is closed in particular in both radial directions and which communicates directly with the pressure chamber, as described in DE 2015 212 641 A1, the contents of which are incorporated by reference as part of the invention.

Particularly preferably, the sealing unit is below a limiting pressure p in the pressure chamber of p <2.0 bar, in particular p <1, 8 bar, preferably p <1, 5 bar and more preferably p <1, 2 bar positioned lifted from the sealing partner.

At a particularly low pressure in the pressure chamber, which is in particular below the minimum tire pressure for the tire, a sealing contact between the sealing unit and the sealing partner can be eliminated. This leads to a correspondingly lower contact pressure of the sealing unit on the sealing partner when a desired setpoint pressure for the pressure space is applied in the pressure chamber. The wear of the sealing unit can be reduced.

Particularly preferred is between the first bearing ring and the second bearing ring a, in particular designed as a cassette seal or radial shaft seal, sealing body provided to protect the rolling elements against external contamination, wherein the seal assembly is arranged in the axial direction between the rolling elements and the sealing body, in particular the seal assembly the sealing body is axially supported and / or the sealing body forms the sealing partner. The sealing body can already seal off the wheel bearing to form an axial side, so that, in particular, dust and other dirt particles are essentially not introduced into the wheel housing. warehouse can penetrate. In this case, the sealing arrangement can form an additional barrier, which can prevent the penetration of contaminants into the area of the rolling bodies. In this case, the sealing body can be used to support one of the sealing partners or itself form the sealing partner on this axial side of the sealing arrangement. Alternatively, the sealing arrangement can replace the sealing body provided at one axial end of the wheel bearing, wherein in particular the sealing partner provided at the axial end of the wheel bearing can be supported on a securing ring inserted in a groove of one of the bearing rings of the wheel bearing.

In particular, a dust cover for covering the rolling elements is provided in the axial direction between the respective sealing partner and the rolling elements facing this sealing partner, wherein in particular the dust cover with the sealing partner forms a labyrinth seal. The dust cover can prevent dirt from entering the area of the roller bearings. As a result, impurities in the pressurized fluid, which could pass through the sealing contact parts as leakage, can not reach the roller bearings. In particular, with the help of the dust cover a flow paths for the leakage flow of the pressurized fluid can be specified, which provides a type of labyrinth seal a 180 ° -Kehre, for example, from radially inward to radially outward or vice versa. This allows the leakage or at least the heavier contaminants of the leakage stream to be retained and collected in the 180 ° turn.

Preferably, downstream of the sealing contact between the sealing unit and the sealing partner, a collecting space is provided for collecting and returning pressurized fluid which has flowed past the sealing contact as a leak. The collecting space can be formed in a bearing ring of the wheel bearing or can be achieved via a channel formed in the bearing ring of the wheel bearing. This can ensure that a leakage current or impurities in the leakage current does not reach the rolling elements. Preferably, the pressure fluid collected in the plenum can be recycled, whereby the plenum can be emptied to a large extent and still after a long period of operation still leakage Ström can absorb at least temporarily. Suitable leakage recirculations are described in DE 10 2006 006 143 A1, the content of which is incorporated herein by reference.

The invention further relates to a wheel bearing arrangement for mounting a motor vehicle tire of a motor vehicle, in particular a truck, with a bearing pin, in particular a hollow shaft at least in a partial area, a bearing pin mounted on the bearing pin for receiving a tire of the motor vehicle, a wheel bearing for Supporting the wheel hub on the bearing journal and a sealing arrangement, which can be trained and educated as described above, radial passage of a pressurized fluid from the bearing pin to the pressure space, wherein the seal assembly is arranged in the axial direction between the wheel bearing and an axial surface of the journal. The sealing arrangement can communicate with an inlet formed by the bearing pin and an outlet formed by the wheel hub, so that the rotary leadthrough can be formed in the axial direction outside the wheel bearing. The sealing arrangement is arranged in particular in the axial direction next to an inner ring and / or next to an outer ring of the wheel bearing. The seal arrangement can be arranged in the axial direction next to a rolling body from contamination protective sealing body and thereby form a further protection against contamination. As a result, the wheel bearing need not be structurally adapted to the design of the rotary feedthrough with the aid of the sealing arrangement. The bearing journal may have, for example, a blind hole to which the pressure source is connected and / or from which the inlet can exit in the radial direction. The sealing arrangement can be fixed axially between the wheel bearing and the axial surface of the bearing journal. In particular, a shaft nut, which presses the wheel bearing against the seal arrangement and thus the seal arrangement against the axial surface acting as an axial stop for the seal arrangement, is screwed onto the end of the bearing journal projecting from the axial surface. An axial play can thereby be eliminated. The invention will now be described by way of example with reference to the accompanying drawings with reference to preferred exemplary embodiments, wherein the features shown below may represent an aspect of the invention both individually and in combination. Show it:

1 is a schematic sectional schematic representation of a rotary feedthrough for a wheel bearing,

2 shows a schematic sectional view of a first embodiment of a Radla- gers with the rotary feedthrough of FIG. 1,

3 shows a schematic sectional view of a second embodiment of a wheel bearing and

4 shows a schematic sectional view of a third embodiment of a wheel bearing.

The rotary feedthrough 10 shown in FIGS. 1 and 2 can, for example, guide a pressurized fluid, in particular as compressed air, through a wheel bearing 12 of a motor vehicle into a radially outer pressure useful space, which is a pressure source The tire tube of a motor vehicle tire can act in order to be able to set the optimum tire pressure that is different for different boundary conditions. The wheel bearing 12 is designed, for example, in two rows and in particular can have two separate rolling bearings 18, which have a common inner ring or separate inner rings. The rotary feedthrough 10 therefore has a first ring 14 and a further first ring 15, which has a radially extending inlet 16, via which the pressure provided by the pressure source can be applied. The first ring 14 and the further first ring 15 can each be formed by the inner ring of the respective associated rolling bearing 18. The inlet 16 is in this case formed only by one of the first rings 14, 15. The rotary feedthrough 10 also has a relative to the first ring 14 relatively rotatable second ring 20 having a radially extending outlet 22 to direct the pressurized fluid into the pressure space. The second ring 20 may in this case be formed, for example, by the outer ring of the roller bearings 18. In the illustrated embodiment The second ring 14 is configured separately from the outer rings of the roller bearings 18 and is designed, for example, by a hub for the tire.

In order to seal the first ring 14 and the second ring 20 as tightly and wear-resistant as possible, the rotary leadthrough 10 has a sealing arrangement 24 arranged in the radial direction between the first ring 14 and the second ring 20. The sealing arrangement 24 has a seal holder 26, in which a sealing unit 38 sealing toward a first axial side and a further sealing unit 60 sealing in an opposite axial direction are used. In the exemplary embodiment shown, the seal holder 26 has the sealing units 38, 60, each axially outwardly engaging first axial stops 30, with the aid of which the sealing units 38, 60 are captively received in the seal holder 26. At the same time presses the seal holder 26, the sealing units 38, 60 against the first ring 14 and the other first ring 15, whereby a seal is achieved. The frictional engagement between the sealing units 38, 60 and the first rings 14, 15 is sufficient for the sealing units 38,

60 and the seal holder 26 with the rotational speed of the first ring 14, 15 rotate. In the axial direction, the sealing units 38, 60 can be clamped between axial stops 28 formed by the first rings 14, 15 and / or axially received. The inlet 16 opens into a pressure chamber 36 which is axially limited by the sealing units 38, 60 and radially delimited by the first rings 14, 15 and the seal holder 26. The pressure chamber 36 is closed on an axially outwardly facing side by the sealing unit 38 which is located inside the Seal holder 26 can be displaced in the axial direction and / or elastically deformed. The sealing unit 38 has a, in particular made of an elastomeric material, retaining ring 40 which on its side facing away from the pressure chamber 36 axial side, in particular elastic, receiving pockets 42, in each of which a rather wear-resistant inelastic support ring 44 and a more elastic Seal 46 are used. Between the receiving pocket 42 and the received ring 44, 46 may be provided a compensating groove. The support ring 44 and the sealing ring 46 are arranged substantially concentric to a rotational axis of the wheel bearing 12, wherein the rotary leadthrough 10 and the seal assembly 24 also to this rotation axis can rotate. By the pressure in the pressure chamber 36, the retaining ring 40 of the sealing unit 38 can be pressed axially outward, so that the support ring 44 and the sealing ring 46 are pressed in the axial direction against a sealing partner 50, whereby a dependent of the pressure in the pressure chamber 36 sufficient and automatic adaptation to changing pressure conditions is achieved. Analogous to the sealing unit 38, the further sealing unit 60 limits the other axial side of the pressure chamber and can be pressed by the pressure in the pressure chamber 36 against another sealing partner 50. The further sealing unit 60 may in particular be designed essentially mirror-inverted to the sealing unit 38 and function analogously. The sealing partner 50 is fixed in rotation with the second ring 20. In addition, the sealing partner 50 has a sealing groove 52 which is open to the second ring 20 and in which, for example, an O-ring (not shown) may be used to adequately seal the sealing partner 50 with respect to the second ring 20. Additionally or alternatively, between the sealing partner 50 and the second ring 20, a rubberized seat can be provided, which enables a sufficient sealing and a rotationally fixed attachment of the sealing partner 50 to the second ring 20. The seal unit 38 rotates at the rotational speed of the first ring 14 while the sealing partner 50 rotates at the rotational speed of the second ring 20. With abrasive wear of the support ring 44 and the sealing ring 46 reduces the axial extent of the support ring 44 and the sealing ring 46. However, the sealing unit 38 can automatically compensate for this wear by the retaining ring 40 by the pressure in the pressure chamber 36 more towards the sealing partner 50 out displaced and / or elastically deformed.

From the pressure chamber 36 is an outlet channel 54, which has a significantly smaller flow cross-section than the inlet 16. The outlet channel 54 can thereby accumulate the pressure fluid in the pressure chamber 36 in the manner of a throttle when filling the pressure working space and generate a back pressure. The kinetic energy of the pressure fluid is converted by the throttling action of the outlet passage 54 into an increase in the static pressure in the pressure chamber 36, which may increase the density of the pressure fluid in the pressure chamber 36, if necessary. When the pressure fluid has passed the exhaust passage 54, the pressurized fluid may flow from the exhaust passage 54 to the outlet 22 and the pressure room to flow. A portion of the pressurized fluid can also flow into a counterpressure gap 56 formed between the sealing partner 50 and the sealing unit 38 and accumulate there. As a result, the contact pressure of the sealing unit 38 on the sealing partner 50 can be reduced.

The rolling bearing 18 of the wheel bearing 12 may have rolling elements 62 between the inner ring and the outer ring. The ingress of contaminants can be prevented by a sealing body 64 designed, for example, as a cartridge seal, which is arranged on the axial outer edge of the roller bearing 18 between the inner ring and the outer ring.

When the pressure space is to be filled with a pressure fluid to increase the pressure, the pressure fluid can first be supplied via the inlet 16 from a pressure source. Subsequently, the pressurized fluid may enter the connected pressure chamber 36 from the inlet 16. Due to the pressure in the pressure chamber 36, the sealing units 38, 60 are pressed against their respective sealing partner 50. Due to the throttling effect of the outlet channel 54, a correspondingly high pressure in the pressure chamber 36 arises due to the dynamic pressure achieved thereby, which leads to a good sealing effect between the sealing units 38, 60 and the respective sealing partner 50. Finally, the pressurized fluid can leave the pressure chamber 36 via the outlet channel 54 and reach the pressure space via the outlet 22 in the second ring 20, which may be formed by a hub of the motor vehicle tire. However, a portion of the pressurized fluid may also enter the counter-pressure gap 56 via a gap formed between the seal holder 26 and the second ring 20. Due to the increased pressure in the pressure chamber 36 with the aid of the outlet channel 54, a sufficient sealing effect is provided at the sealing contact point between the respective sealing unit 38, 60 and the associated sealing partner 50 in order to prevent or at least minimize leakage. As a result of the gradual equalization of pressure between the pressure source and the pressure space, the pressure in the counter-pressure gap 56 can also increase gradually and reduce the contact pressure of the sealing units 38, 60 on the associated sealing partner 50 to a still sufficient but low-wear extent. In the embodiment of the wheel bearing 12 shown in FIG. 3, in comparison to the embodiment of the wheel bearing 12 shown in FIGS. 1 and 2, the first axial stops 30 of the retaining ring 26 can be abutted by the back sides of the sealing units 38, 60 facing the pressure chamber 36 second axial stops 32 replaced. By the second axial stops 32 is between the sealing units 38,

60 predetermined a minimum distance and a minimum axial extent of the pressure chamber 36, so that the inlet 16 can not be covered by the sealing units 38, 60. In particular, it is also possible that the seal holder 26 has both the first axial stops 30 and the second axial stops 32, between each of which the associated sealing unit 38, 60 is received.

In the embodiment of the wheel bearing 12 shown in FIG. 4, in comparison to the embodiment of the wheel bearing 12 shown in FIG. 3, a spacer ring 48 is provided in the axial direction between the sealing units 38, 60. The spacer ring 48 has an inlet channel 34 communicating with the inlet 16 and with the pressure chamber 36, the flow cross section of which is essentially as large as the flow cross section of the inlet 16. Preferably, the seal holder 26 presses the sealing units 38, 60 against both the first rings 14, 15 and against the spacer ring 48. The spacer ring 48 is designed, in particular, to lock the first ring 14 to the second ring 15. Due to the radial extent of the spacer ring 48, the radial extent of the pressure chamber 36 can be reduced and the axial area of the rear side of the respective sealing unit 38, 60 facing the pressure chamber 36 can be correspondingly reduced, so that the contact pressure of the sealing units 38, 60 at the respective sealing partner 50 can be reduced to a required extent. Reference number list Rotary feedthrough

Wheel bearings

first ring

another first ring

inlet

Rolling

second ring

outlet

sealing arrangement

seal holder

axial stop

first axial stop

second axial stop

inlet channel

pressure chamber

sealing unit

retaining ring

receiving pocket

support ring

seal

spacer ring

sealing partner

sealing groove

exhaust port

Backpressure gap

further sealing unit

rolling elements

sealing body

Claims

claims

1. Wheel bearing for storing a motor vehicle tire of a motor vehicle, in particular truck, with

a, designed in particular as an inner bearing ring, first ring (14),

a, designed in particular as an outer bearing ring or hub, relative to the first ring (14) rotatably mounted second ring (20),

a rotationally fixed with the second ring (20) directly or indirectly fastened sealing partner (50),

a rotationally fixed with the second ring (20) directly or indirectly fixed further sealing partner (50),

a pressure chamber (36) formed in the radial direction between the first ring (14) and the second ring (20) and in the axial direction between the sealing partner (50) and the further sealing partner (50),

a sealing unit (38) delimiting the pressure chamber (36) on a first axial side and axially displaceable as a result of a pressure in the pressure chamber (36) and / or axially elastically deformable for producing a sealing contact with the sealing partner (50),

a further sealing unit (60) delimiting the pressure chamber (36) at a second axial side different from the first axial side and axially displaceable as a result of a pressure in the pressure chamber (36), for producing a sealing contact with the further sealing partner (50) and

a seal holder (26) delimiting the pressure chamber (36) on a radial outer surface facing away from the first ring (14), the seal holder (26) sealingly sealing the sealing unit (38) and the further sealing unit (60) to a lateral surface of the seal press first ring (14),

wherein the first ring (14) has an inlet (16) communicable with the pressure chamber (36), the seal holder (26) having an outlet channel (54) communicable with the pressure chamber (36) and with an outlet (22) formed in the second ring (20),

wherein the flow cross-section of the outlet channel (54) is dimensioned for conveying a pressurized fluid from a pressure source adjacent to the inlet (16) to a pressure space adjacent the outlet (22), in particular a tire of a motor vehicle tire, in the pressure chamber (36) Back pressure for sealingly pressing the sealing unit (38) on the sealing partner (50) and for sealingly pressing the further sealing unit (60) to the other sealing partner (50).

2. Wheel bearing according to claim 1, characterized in that the seal holder (26) has a first axial stop (30) for retaining the sealing unit (38) in the pressure chamber (36) and / or a further first axial stop (30) for retaining the other Sealing unit (60) in the pressure chamber (36).

3. Wheel bearing according to claim 1 or 2, characterized in that the seal holder (26) has a second axial stop (32) for abutment of a sealing partner (50) facing away from the rear side of the seal unit (38) and / or a further second axial stop ( 32) for abutment has a back of the further sealing unit (60) facing away from the further sealing partner (50).

4. wheel bearing according to one of claims 1 to 3, characterized in that at one of the pressure chamber (36) facing lateral surface of the first ring (14) between the sealing unit (38) and the further sealing unit (60) arranged spacer ring (48) is provided, wherein the spacer ring (48) sealingly in the radial direction of the sealing unit (38) and the further sealing unit (60) and having an inlet (16) communicable with the inlet channel (34), wherein in particular, the flow cross section of the inlet channel (34) is at least as large as the flow cross section of the inlet (16).

5. Wheel bearing according to one of claims 1 to 4, characterized in that a relative to the second ring (20) rotatably mounted and the first ring (14) separate further first ring (15) is provided, wherein the first ring (14) and the further first ring (15) viewed in the radial direction each cover a part of the pressure chamber (36), wherein the inlet (16) is provided either only in the first ring (14) or only in the further first ring (15).

6. wheel bearing according to claim 5, characterized in that the inlet (16) to a contact point between the first ring (14) and the further first ring (15) is positioned in the axial direction spaced apart.

7. wheel bearing according to claim 5 or 6, characterized in that the inlet

(16) is positioned off-center in the axial direction to the pressure chamber (36) and / or to the seal holder (26).

8. Wheel bearing according to one of claims 5 to 7, characterized in that at one to the pressure chamber (36) facing lateral surface of the first ring (14) and the further first ring (15) between the sealing unit (38) and the further sealing unit (60 ), said spacer ring (48) having an inlet port (34) communicable with said inlet (16), said spacer ring (48) having both said first ring (14) and said further first ring (15) is connected, in particular in order to press the first ring (14) and the further first ring (15) in the axial direction to each other.

9. Wheel bearing according to claim 8, characterized in that the spacer ring (48) engages with a retaining hook and / or a retaining collar in the inlet (16).

10. Wheel bearing according to claim 8 or 9, characterized in that a fastening tion of the spacer ring (48) with the first ring (14) and / or with the other first th ring (15) via a resiliently past at least one latching intersection latching lug he follows.