DE102017115978A1 - Nanotechnology in wheel bearings - Google Patents

Abstract

The invention relates to a wheel bearing (1), wherein at least a part of the wheel bearing (1) for improving the properties of the wheel bearing (1) is provided with a hydrophobic coating (10). Another object of the invention is a method for producing a wheel bearing (1), wherein the wheel bearing (1) is coated with a hydrophobic coating (10).

Description

This invention relates to a wheel bearing with a coating. Furthermore, the invention relates to a method for producing a wheel bearing. Such a wheel bearing can be used, for example, as a wheel bearing of a vehicle, in particular of cars and trucks.

Often, according to the prior art, a multi-stage sealing system is provided, which has a gap seal with respect to the outside world and this has a lip seal. In the operation of wheel bearings, especially in the open, as is the case for example with wheel bearings of vehicles, it happens that water penetrates through the gap seal in the camp. From there, there is the danger that the water penetrates through the lip seal in the bearing interior, which is critical in particular for wheel bearings, as this can lead to corrosion of the rolling elements and the raceways. With the water also dirt can penetrate into the camp. Since dirt often contains very hard constituents, this is an additional danger to the bearing. Wheel bearings with coatings for improved corrosion resistance are known in the art. However, these do not have the optimal properties.

The object of the invention is to improve the corrosion and contamination properties of wheel bearings.

This object is achieved by the features of the independent claims. Further advantageous developments are the subject of the dependent claims.

The invention relates to a wheel bearing, of which at least a part is provided with a hydrophobic coating to improve its properties.

Such a water-repellent coating results in faster drainage of water as well as less remaining water in the store. This reduces the risk of corrosion. In addition, a hydrophobic coating has dirt-repellent and wear-reducing properties. A hydrophobic coating can also affect the flow of fat in a fat cycle.

Preferably, the coating has properties caused by microstructures or nanostructures of the coating. The use of fine structures has an influence especially on the capillary behavior of a surface. As a result, hydrophobic properties can be generated independently of the choice of a coating material. However, a suitable coating material can support the hydrophobic behavior.

The coating preferably exhibits a lotus effect with respect to water. This is possible because the hydrophobic coating has micro- or nano-sized tips that are on the order of a few hundred nanometers to about ten micrometers apart such that a peak effect with increased capillary repulsion is realized over virtually the entire coated area. Water can bead off in large drops and does not remain on the surface. In this way, also penetrating dirt is washed away and does not settle on the surface.

The expression of the effect of the beading depends on a contact angle of the coating to water. Since water would like to cling more or less strongly to the surface, depending on the degree of hydrophobicity, it forms broad puddles on a little hydrophobic surface, while it is rejected on a strongly hydrophobic surface and becomes more or less strong due to its internal capillary action Contracting drops. The contact angle is defined between the edge of the drop or puddle and the surface of the coating. The bigger it is, the sooner water contracts into a single drop. Drops on a highly hydrophobic surface may bead off. Depending on the hydrophobicity of the surface this takes place at different angles of inclination of the surface. The more hydrophobic a surface is, the lower the tendency can be from which even a beading takes place. The lotus effect causes a much greater hydrophobicity than nano- or microstructured surfaces would do even from highly water-repellent material.

Preferably, the contact angle between the coating and water is so great that water will bead even if it would not bead off a smooth layer of polytetrafluoroethylene. Such a strong hydrophobicity allows the entrainment of dirt in water, which is a significant advantage when used in dirt-sensitive wheel bearings.

The draining of drops over the surface of the coating preferably entails the entrainment of dirt deposited there. The contact angle between the coating and water is preferably so pronounced that the coating is sufficiently wettable for the purpose of cleaning dirt particles.

In particular, the coating is a plasma polymer coating. This has the advantage of being plasma-coated, among others a polysiloxane-based coating can be produced.

Preferably, the coating is a polysiloxane-based coating. Such a coating is advantageously very durable. Since wheel bearings generally need to have a long life, the effect of such a coating can also be maintained for a long time. However, it is also conceivable to use fluorine-based coatings. Although these are less durable in the current state of the art, so that the desired purpose over a period of time can be met.

The coating is preferably arranged on a surface or a surface section of the bearing interior, a catching chamber, an encoder surface, a seat surface of an outer ring and / or on a running surface of a seal.

Preferably, a bearing interior, in which rolling elements are provided with a hydrophobic coating. This has the advantage that it can influence the grease management. In particular, with the nanocoating grease is guided specifically to the raceways. As a result, a supply of grease generated on the rolling elements of its structure are supported, resulting in a durable good lubrication of the wheel bearing.

In particular, a catching chamber of a wheel bearing, which is preferably separated from the outer world by a gap seal and by a lip seal from the rolling elements of a wheel bearing, is coated with a hydrophobic coating. The catching chamber is preferably designed as an annular groove, in particular in a sealing ring. In particular, the theoretical longitudinal axis of such a bearing is aligned at least approximately horizontally during operation. Penetrating polluted water is transported by the running water in the catching chamber down, carrying the dirt with it. From the gap seal, the water that collects in the lower part of the catching chamber, improved by the increased pressure of the accumulating water through the gap improved emerge again.

Preferably, a surface of an encoder, which is connected to the wheel bearing and preferably integrated in this, provided with a hydrophobic coating. In this way, accumulations of dirt and thus signal failures can be avoided.

Preferably, a hydrophobic coating is applied to the outer ring of a bearing, in particular on the seat surface of the outer ring, which is in many cases its outer peripheral surface. The outer ring is particularly susceptible to corrosion, especially since its outside is often not surrounded by grease. By means of a hydrophobic coating, it is possible to ensure that little or no water accumulates there, thus preventing corrosion.

Preferably, a hydrophobic coating is applied to the mating surface of the sealing lips. Preferably, this is an abrasion resistant coating. Due to the repellent effect of the coating, a reduction in wear can be achieved. In addition, since dirt on the coating can be poor, the life is reduced by entrained particles and corresponding wear less.

Preferably, a hydrophobic coating is applied to a bearing surface which is susceptible to stress corrosion cracking. The rejection of water reduces or prevents stress corrosion cracking.

Preferably, the wheel bearing is suitable for a motor vehicle, preferably for a passenger car or a truck. The advantages of the invention are particularly strong here.

In a further aspect of the invention, the wheel bearing is coated with a hydrophobic coating. The advantages described above are achieved.

1. 1) Ein nanoversiegelter Lagerinnenraum soll eine verbesserte Fettführung zur Laufbahn hin bewirken.
2. 2) Eine nanoversiegelte Fangkammer soll zu einem verbesserten Abfluss von Schmutzwasser/Schmutzpartikeln führen.
3. 3) Eine nanoversiegelte Encoderoberfläche soll Schmutzanhäufungen und somit Signalausfälle vermeiden.
4. 4) Ein nanoversiegelter Außenring-Sitz soll zu verbessertem Korrosionsschutz führen.
5. 5) Eine nanoversiegelte Gegenlauffläche der Dichtungen soll verbesserten Verschleißschutz bewirken.
6. 6) Nanoversiegelte Oberflächen sollen die Spannungsrisskorrosion reduzieren.

In other words, a targeted application of nanotechnology in the wheel bearing should result in the following improvements:

1. 1) A nano-sealed bearing interior is intended to bring about an improved grease guide to the raceway.
2. 2) A nano-sealed catching chamber should lead to an improved drainage of dirty water / dirt particles.
3. 3) A nano-sealed encoder surface is to avoid accumulation of dirt and thus signal failures.
4. 4) A nano-sealed outer ring seat should lead to improved corrosion protection.
5. 5) A nano-sealed mating surface of the seals should provide improved wear protection.
6. 6) Nano-sealed surfaces should reduce stress corrosion cracking.

1. 1) Es soll ein nanobeschichteter Lagerinnenraum vorgesehen werden, um eine gezielte Fettführung hin zu den Laufbahnen zu realisieren.
2. 2) Eine nanoversiegelte Fangkammer kann im Bereich der Fangkammer aufgebracht werden. Es bestehen hier keine mechanischen Belastungen, wodurch hier die Haltbarkeit der Schicht dauerhaft gewährleistet wird. Bei der durch die Nanotechnologie erzeugten Schicht im Bereich der Fangkammer muss die Oberfläche der Beschichtung einen idealen Kontaktwinkel aufweisen, damit die gewünschte Wirkung erzielt werden kann. Dies bedeutet, dass der Kontaktwinkel so ausgeprägt sein sollte, dass eindringendes Wasser zwar abläuft, jedoch die Oberfläche zum Reinigen der Fangkammer ausreichend benetzt werden kann.
3. 3) Eine nanoversiegelte Encoderoberfläche soll im Bereich des Encoders bewirken, dass durch verbesserte Gleiteigenschaften geringere mechanischen Belastungen auftreten.Durch diese und weitere Eigenschaften der Beschichtung soll die Haltbarkeit der Schicht ebenfalls dauerhaft gewährleistet werden. Die Nanobeschichtung verhindert in diesem Bereich die Schmutzanhäufungen und verhindert somit die bekannten Signalausfälle.
4. 4) Die Aufbringung einer Schutzschicht, insbesondere einer Nanobeschichtung, soll einen Korrosionsangriff verhindern.
5. 5) Die Aufbringung einer Beschichtung auf die Gegenlauffläche der Dichtlippen soll eine Verschleißreduzierung bewirken.

A layer produced by nanotechnology has a low surface energy. This means hydrophobicity and thus water-repellent properties. As a result, there is a low chemical attraction to overlying substances such as water or dirt particles.

1. 1) A nano-coated bearing interior is to be provided in order to realize a targeted grease management towards the raceways.
2. 2) A nano-sealed catching chamber can be applied in the area of the catching chamber. There are no mechanical stresses here, whereby here the durability of the layer is permanently guaranteed. In the case of the nanotechnology-generated layer in the area of the catching chamber, the surface of the coating must have an ideal contact angle so that the desired effect can be achieved. This means that the contact angle should be so pronounced that while penetrating water drains, but the surface can be sufficiently wetted to clean the trap chamber.
3. 3) A nano-sealed encoder surface in the area of the encoder should cause lower mechanical stresses to occur as a result of improved sliding properties. These and other properties of the coating should also ensure the long-term durability of the coating. The nano-coating prevents dirt accumulation in this area and thus prevents the known signal failures.
4. 4) The application of a protective layer, in particular a nano-coating, should prevent a corrosion attack.
5. 5) The application of a coating on the mating surface of the sealing lips should cause a reduction in wear.

One can distinguish between short-lived and long-lasting coating solutions. Short-lived solutions often work through the "lotus effect". It describes predominantly fluorine-based layers (for example PTFE coatings - Teflon pan, Ultra ever dry coating). A long-lasting coating solution is e.g. a plasma polymer coating (e.g., a polysiloxane-based coating). For the application in wheel bearings, the long-lasting coating solutions have the highest priority. However, short-lived solutions are also possible.

• 1 Eine Schnittansicht eines Radlagers mit einer Fangkammer, einem Lagerinnenraum, einer Gegenlauffläche, einer Encoderfläche und einer Sitzfläche des Außenrings;
• 2 eine Schnittansicht eines Radlagers mit einer hydrophoben Beschichtung des Lagerinnenraums;
• 3 eine Schnittansicht einer Fangkammer eines Radlagers;
• 4 einen vergrößerten Ausschnitt aus der 3;
• 5 eine Schnittansicht einer Lippendichtung des Radlagers und ihrer Gegenlauffläche vor einer Beschichtung;
• 6 einen vergrößerten Ausschnitt aus der 5 nach einer Beschichtung;
• 7 eine Schnittansicht einer Encoderfläche vor einer Beschichtung;
• 8 einen vergrößerten Ausschnitt aus der 7 nach einer Beschichtung;
• 9 eine Schnittansicht einer Fangkammer und eines Außenrings eines Radlagers;
• 10 eine Schnittansicht einer Gegenlauffläche einer Dichtlippe eines Radlagers auf der Radseite; und
• 11 eine Schnittansicht einer Gegenlauffläche einer Dichtlippe eines Radlagers auf der Getriebeseite.

The invention will be explained in more detail by means of embodiments in conjunction with accompanying drawings. Here are shown schematically:

• 1 A sectional view of a wheel bearing with a catching chamber, a bearing interior, a mating surface, an encoder surface and a seating surface of the outer ring;
• 2 a sectional view of a wheel bearing with a hydrophobic coating of the bearing interior;
• 3 a sectional view of a catching chamber of a wheel bearing;
• 4 an enlarged section of the 3 ;
• 5 a sectional view of a lip seal of the wheel bearing and its mating surface before a coating;
• 6 an enlarged section of the 5 after a coating;
• 7 a sectional view of an encoder surface in front of a coating;
• 8th an enlarged section of the 7 after a coating;
• 9 a sectional view of a catching chamber and an outer ring of a wheel bearing;
• 10 a sectional view of a mating surface of a sealing lip of a wheel bearing on the wheel side; and
• 11 a sectional view of a mating surface of a sealing lip of a wheel bearing on the transmission side.

In the following description, like reference characters will be used for like items.

1 schematically shows a cross section through a wheel bearing 1 as a wheel bearing 40 is trained. The wheel bearing 40 has an outer ring 3 and an inner ring 2 on. The inner ring 2 is in the embodiment shown partially by an inner ring member 41 a split inner ring and partly from the wheel hub 42 formed, with the wheel hub 42 with a career 44 for rolling elements 43 is provided. Next, the wheel bearing has a bearing interior 21 , a catching chamber 22 , an encoder surface 23, a seat 24 of the outer ring 3 and at each axial end of the wheel bearing 40 at a catch chamber 27 each a mating surface for the sealing rings 26 on.

The inner ring 2 sits down in a wheel hub 42 continued. While the outer ring 3 stands, rotates the inner ring 2 operational. The wheel bearing 40 is designed as a double row wheel bearing.

2 shows a cross section through the wheel bearing 40 in which the warehouse interior 21 with a hydrophobic coating 10 is provided.

The coating 10 preferably has a nano- or microstructuring, which contributes to the hydrophobicity.

The coating 10 extends over the raceways 29 of the inner ring 2 , over the careers 30 of the outer ring 3 and via a raceway interface 31 of the outer ring 3 and a raceway interface 32 of the inner ring 2 , In the warehouse interior 21 is fat 33 introduced, which is the operation of the wheel bearing 40 moved in a grease circuit.

This fat cycle is made by hydrophobic coatings 10 promoted. At the rolling elements 43 Formed by the stripping of grease and the promotion to the rolling elements 43 or to the raceways 29 . 30 on a grease wiper ring 34 fat stores 28 from what a part TFK of the grease circuit forms.

With the fat stores 28 become the rolling elements 43 re-lubricated. The fat 33 is also in operation by the rolling elements 43 thrown off and along the raceway surfaces 31 . 32 in the grease conveying direction FF back to the fat stores 28 conveyed back. Due to the hydrophobic properties, in particular the raceway surfaces 31 . 32 , the fat circulation is accelerated, which is advantageous for lubrication.

3 shows a cross section through a catching chamber 22 a sealing ring 6 ,

The sealing ring 6 includes next to the catching chamber 22 two sealing lips 5 , The sealing lips 5 run to a mating surface 7 At the wheel hub 42 circulates. The sealing ring 6 is on the outer ring 3 attached and is in operation.

The catching chamber 22 is in the 3 not yet coated with a hydrophobic layer, which corresponds to the prior art.

4 shows the section A from 3 in an enlarged view.

The catching chamber 22 is with a hydrophobic coating 10 coated. As it is at the catching chamber 22 Water is circulating in the catching chamber around a circumferential annular groove 22 has penetrated, run down the groove and there from the in 3 only at the bottom of the sealing ring 6 shown annular gap 4 exit again.

The coating 10 with low surface energy has a low attraction to overlying substances such as water or dirt particles. Water would bead drop-shaped on entry and flush as a side effect adhering dirt particles from the surface.

5 shows a cross section through a sealing ring 6 , which two sealing lips 5 having.

The sealing lips 5 run to a mating surface 7 on, with the sealing lips 5 in reality not in the mating surface 7 penetration.

Above the upper sealing lip 5 Is a catching chamber 22 trained in the 5 is shown uncoated. The catching chamber 22 has as well as in the 3 shown a connection to an annular gap 4 which represents a gap seal.

6 shows an enlarged view of the catching chamber 22 from the 5 but with a hydrophobic coating 10 ,

The hydrophobic coating 10 extends into the annular gap 4 , The low surface energy coating has a low attraction to overlying substances such as water or dirt particles.

Penetrated water would bead drop-shaped and flush as a side effect adhering dirt particles from the surface.

7 equals to 5 , where in both an uncoated encoder surface 8th is shown.

8th shows an enlarged section of the 7 with an encoder surface 8th that with a hydrophobic coating 10 is coated.

Through the coating 10 the encoder surface remains 8th clean, so that errors in capturing encoder values are avoided.

9 shows a cross section through a sealing ring 6 standing on an outer ring 3 is plugged.

The outer ring 3 is on a seat 24 for the sealing ring 6 , which is particularly susceptible to corrosion by contact with water, with a hydrophobic coating 10 coated.

This hydrophobic coating protects the outer ring 3 from corrosion by repelling water that forms the outer ring 3 could corrode.

The coating 10 Also protects against the water between the sealing ring 6 and the outer ring 3 penetrates and causes corrosion there.

10 shows a mating surface 7 for a sealing ring on the wheel side of a wheel bearing, which rotates with the wheel hub, not shown.

The mating surface 7 carries on its surfaces, against which the sealing lips, not shown, a hydrophobic coating 10 , Through the coating 10 the wear of the sealing lips is reduced.

11 shows a mating surface 7 for a sealing ring on the transmission side of a wheel bearing, which rotates with the wheel hub, not shown.

The mating surface 7 carries on its surfaces, against which the sealing lips, not shown, a hydrophobic coating 10 , Through the coating 10 the wear of the sealing lips is reduced.

LIST OF REFERENCE NUMBERS

1

Wheel bearings

2

inner ring

3

outer ring

4

annular gap

5

sealing lip

6

sealing ring

7

Mating surface

8th

encoder area

10

coating

22

trap chamber

21

Warehouse interior

24

Seat of an outer ring for the sealing ring

25

Mating surface of a seal

26

sealing ring

27

trap chamber

28

fat stock

29

Raceway of the inner ring

30

Raceway of the outer ring

31

Raceway surface of the outer ring

32

Raceway surface of the inner ring

33

fat

40

Wheel bearings

41

Inner ring element of a split inner ring

42

wheel hub

43

rolling elements

44

Raceway of the wheel hub

FF

Fat conveying direction

TFK

Part of the fat cycle

Claims (10)

Wheel bearing (1), characterized in that at least a part of the wheel bearing (1) to improve the properties of the wheel bearing (1) is provided with a hydrophobic coating (10). Wheel bearing (1) to Claim 1 , characterized in that the coating (10) has microstructures or nanostructures of the coating (10) caused properties. Wheel bearing (1) according to one of the preceding claims, characterized in that the coating (10) shows a lotus effect with respect to water. Wheel bearing (1) according to any one of the preceding claims, characterized in that the contact angle between the coating (10) and water is so pronounced that water even when it would not bead off a smooth layer of polytetrafluoroethylene. Wheel bearing (1) according to one of the preceding claims, characterized in that the contact angle between the coating (10) and water is so pronounced that the coating (10) for the purpose of cleaning dirt particles (11) is sufficiently wettable. Wheel bearing (1) according to one of the preceding claims, characterized in that the coating (10) is a plasma polymer coating. Wheel bearing (1) according to one of the preceding claims, characterized in that the coating (10) is a polysiloxane-based coating (10). Wheel bearing (1) according to one of the preceding claims, characterized in that the coating (10) on a surface or a surface portion of the bearing interior (21), a catching chamber (22), an encoder surface (23), a seating surface of an outer ring (24) and / or on a running surface (25) of a seal (26) or a surface of the wheel bearing (1) susceptible to stress corrosion cracking. Wheel bearing (1) according to one of the preceding claims, characterized in that the wheel bearing (1) is a wheel bearing (40) for a vehicle, preferably for a motor vehicle, and particularly preferably for a passenger car or a truck. Method for producing a wheel bearing (1), characterized in that the wheel bearing (1) is coated with a hydrophobic coating (10).

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