DE102019104702A1 - camp - Google Patents

Abstract

The invention relates to a bearing (1) comprising a first bearing ring (2) and a second bearing ring (3), which are arranged rotatably relative to one another, the first bearing ring (2) having a contact surface (4) for contact with a first component and the second bearing ring (3) has a contact surface (5) for contact with a second component. In order to ensure reliable electrical insulation of the bearing ring without impairing the geometric dimensions, the invention provides that at least one of the bearing rings (2, 3) at least one having an electrically insulating insulation layer (6) which is arranged at a distance from the contact surface (4, 5).

Description

Field of invention

The invention relates to a bearing comprising a first bearing ring and a second bearing ring which are arranged rotatably relative to one another, the first bearing ring having a contact surface for contact with a first component and the second bearing ring having a contact surface for contact with a second component.

Background of the invention

A bearing of the generic type is for example in the DE 10 2013 104 186 A1 and in the DE 10 2014 224 153 A1 described. It is provided that an outer surface of the bearing ring, this can be the surface adjacent to another component, but also the raceway of the bearing ring, is provided with an electrically insulating coating.

In electrical machines, the currents generated during operation can cause damage to running surfaces, rolling elements and lubricants in the bearing when they pass through or discharge. Depending on the motor power and the use of frequency converters, discharge currents or high-frequency circular currents arise. Damage can only be effectively prevented by a combination of current discharge and insulation.

Various solutions are conceivable to counter this problem. In addition to the options described above, bearings with ceramic rolling elements can also be used, which have an insulating effect due to the material used. The costs and the resulting mechanical and dynamic properties are sometimes problematic.

Insulating coatings are also known. In the course of time, the disadvantage of coated running surfaces is wear of the coating, which at the same time leads to a failure of the insulating effect. Another problem is that when the bearing outer ring surface is coated, the coating may slide off during assembly, which in turn impairs the function.

Bearing protection rings are also used to reduce induced stresses. Such rings can be screwed in front of a bearing and dissipate the stresses by means of carbon fiber brushes distributed around the circumference. The disadvantage of this solution is the risk of contamination of the carbon fiber brushes or of lubricant and thus a restriction in the functionality of the conductivity. Furthermore, the brushes lying radially do not have an active readjusting function, which means that it is not possible to react to fibers breaking off when the direction of rotation is changed. Broken particles are disadvantageously deposited in the lubricant or in the bearing.

Furthermore, electrically conductive nonwovens are known which can be attached or glued to radial shaft sealing rings and which enable current to pass through a bearing. The disadvantage of this concept is the axial installation space requirement and the very limited adjustment of the conductive components.

Object of the invention

The present invention is based on the object of providing a bearing of the type mentioned at the outset, in which there is reliable electrical insulation of the bearing ring without the risk of impairment of the geometric dimensions. Furthermore, the assembly of the bearing should be problem-free and not endanger the desired insulation.

Summary of the invention

According to the invention, this object is achieved in a bearing according to the preamble of claim 1 in such a way that at least one of the bearing rings has at least one electrically insulating insulation layer which is arranged away from the contact surface.

Likewise, the electrically insulating insulation layer is preferably also arranged at a distance from that surface of the bearing ring which faces the other bearing ring. The insulation layer is accordingly located inside the bearing ring, as far as its extent between the adjacent component and the other bearing ring is concerned.

The first bearing ring is preferably an outer bearing ring, and the second bearing ring is an inner bearing ring. Furthermore, the bearing is preferably a roller bearing in which roller bodies are arranged between the bearing rings.

As mentioned, the insulation layer should be placed in the interior of the bearing ring. Accordingly, a preferred embodiment provides that it is arranged in a radial area between 10% and 90% of the radial extent of the bearing ring.

The insulation layer preferably has a hollow cylindrical shape.

The insulation layer preferably has a radial thickness which is between 0.1% and 5% of the radial extent of the bearing ring.

The insulation layer is preferably made of aluminum oxide (Al ₂ O ₃ ). If there are concerns about brittleness, zirconium oxide or titanium carbide can also be used to advantage.

Certain elastic or resilient properties can be achieved if, according to another embodiment of the invention, the insulation layer consists of a plastic.

A further development of the invention provides that a part of the bearing ring adjoining the insulation layer is designed as a hollow cylindrical metal sleeve.

It can be provided that only the first bearing ring, only the second bearing ring or both the first bearing ring and the second bearing ring have an insulation layer.

Thus, according to the invention, a hybrid bearing ring (bearing outer ring and / or inner ring) is provided as well as a corresponding bearing using the same, which has a very high electrical resistance due to a coating or filling with the insulating material (preferably aluminum oxide). Furthermore, there is a high compressive strength. It is particularly advantageous that a high surface quality and dimensional accuracy can be ensured, since the functional surfaces are retained in their original state, taking into account the tolerances of the bearing ring or bearing.

The proposed bearing ring is thus formed in at least two parts, with a filling made of the insulation material between the two parts, which connects the partial rings to form a component.

• Es hat eine sehr gute elektrische Isolation (10¹⁴ bis 10¹⁵ Ωcm). Weiterhin hat es eine sehr hohe Druckfestigkeit (2.000 bis 4.000 MPa). Es hat eine hohe Härte (15 bis 19 GPa) sowie eine hohe Korrosions- und Verschleißbeständigkeit. Vorteilhaft ist auch eine geringe Dichte (3,75 bis 3,95 g/cm³).

The low electrical conductivity and high dielectric strength of the aluminum oxide which is preferred for use in the present invention is also used in the manufacture of insulators and spark plugs. The aluminum oxide introduced, for example by plasma spraying, has particular advantages for the application:

• It has very good electrical insulation (10 ¹⁴ to 10 ¹⁵ Ωcm). It also has a very high compressive strength (2,000 to 4,000 MPa). It has a high hardness (15 to 19 GPa) as well as high corrosion and wear resistance. A low density (3.75 to 3.95 g / cm ³ ) is also advantageous.

The highest operating temperature without mechanical load is between 1,000 ° C and 1,500 ° C.

The material is bioinert and food safe.

• Eine stromisolierende Verbindungsschicht ist zuverlässig bereitgestellt. Der Werkstoff der elektrischen Isolation ist kostengünstig. Es liegen keine Beeinträchtigungen der geometrischen Maße vor, insbesondere spielt die Art und Weise der Montage diesbezüglich keine Rolle; es gibt also keine Funktionsbeeinträchtigung der strom leitenden Funktion durch die Montage. Es ergibt sich weiterhin keine negative Beeinflussung der Druckfestigkeit. Somit ist die gewünschte Funktion zuverlässig gewährleistet.

When used for a roller bearing, the following advantages result:

• A current insulating connection layer is reliably provided. The material of the electrical insulation is inexpensive. There are no impairments to the geometric dimensions, in particular the type of assembly is irrelevant in this regard; So there is no functional impairment of the conductive function by the assembly. Furthermore, there is no negative impact on the compressive strength. The desired function is thus reliably guaranteed.

Figure list

• 1 den Radialschnitt durch ein Wälzlager und
• 2 in vergrößerter Darstellung den Radialschnitt durch den Außenring des Wälzlagers.

A preferred embodiment of the bearing designed according to the invention is explained in more detail below with reference to the accompanying drawings. Show:

• 1 the radial section through a roller bearing and
• 2 enlarged view of the radial section through the outer ring of the roller bearing.

Detailed description of the drawings

In the figures is a roller bearing 1 shown, which has a first bearing ring 2 in the form of an outer bearing ring and a second bearing ring 3 having in the form of a bearing inner ring. Between the bearing rings 2 , 3 are rolling elements 7th arranged.

Will the rolling bearing 1 installed, the outer ring makes contact 2 an adjacent component (e.g. a housing), not shown, on a contact surface 4th ; the inner ring contacts accordingly 3 an adjacent component (not shown) (e.g. a shaft) on the contact surface 5 .

It is essential that at least one of the bearing rings, in the exemplary embodiment it is the bearing outer ring 2 , an insulation layer 6th has, which has an electrically insulating effect. As can be seen from the illustration in the figures, the electrically insulating insulation layer 6th from the contact surface 4th remotely located. So it is practically inside the bearing, as it is in particular 2 results.

Accordingly, it has here as a hollow cylindrical layer 6th formed insulation layer has a radial thickness D, which is only a small part of the entire radial extension E of the bearing ring 2 has, preferably between 0.1% and 5% of the radial extent E. The radial position of the insulation layer 6th is preferably at least 10% of the radial extension E away from the contact surface 4th . The same applies to the distance from the radially inner surface of the bearing outer ring 2 which is the raceway for the rolling elements 7th having. This distance is with a (distance from the contact surface 4th ) or with b (distance from the radially inner surface of the bearing ring) in 2 registered.

The radially outer section of the bearing outer ring 2 is through a metal sleeve 8th formed on the inner part 9 of the bearing outer ring 2 is pushed axially after on the inner part 9 the insulation layer 6th was applied, e.g. B. by a spraying process.

In the exemplary embodiment, it is therefore provided that the outer part of the bearing outer ring 2 is designed thin-walled as a sheet metal sleeve, the space between the inner part 9 and metal sleeve 8th is filled with aluminum oxide. The insulation layer 6th , which therefore preferably consists of aluminum oxide, can be introduced in different thicknesses. The good insulation and the high pressure resistance of the material are very advantageous.

Aluminum oxide occurs naturally as corundum or emery, it is mainly obtained from bauxite, which contains 40% to 60% Al ₂ O _3, different proportions of other oxides (mainly SiO ₂ , besides Fe ₂ O ₃ , TiO ₂ etc.) . Depending on the SiO ₂ content, the raw material is digested up to the desired purity either dry (with a high SiO ₂ content), ie by burning with soda and lime in an oven, or wet (low SiO ₂ content) with NaOH in an autoclave (Bayer process). For wettable powders, DIN 32 529 specifies a purity of at least 99.5%.

Because of its high hardness, the excellent electrical insulation properties and its chemical resistance, but also not least because of its low price, Al ₂ O _{3 is} a widely used and versatile spray material, which is also shown by the fact that Al ₂ O _{3 is included} in the specialist literature practical investigations but also in a wide variety of models and numerical simulations is represented above average.

If there are concerns about the brittleness of the material, zirconium oxide or titanium carbide can also be used; these materials have a higher toughness.

In the exemplary embodiment, only the bearing outer ring is 2 with the insulation layer 6th Mistake. However, this layer can also be analogous in the bearing inner ring 3 to be placed. Finally, it is also possible to have both bearing rings each with at least one insulation layer 6th to provide. Both bearing rings are each provided with an insulation layer 6th provided, the insulation effect is further increased or improved.

The proposed concept can in principle also be used for other components in order to electrically isolate sections of the components from one another.

If the compressive strength and thus the load capacity of the bearing are not decisive, a polymer can also be injected instead of the aluminum oxide that is preferably used. In particular, to achieve a damping effect, an elastomer can also be used in this respect.

List of reference symbols

1

Bearings

2

first bearing ring (bearing outer ring)

3

second bearing ring (bearing inner ring)

4th

Contact surface for contact with a first component

5

Contact surface for contact with a second component

6th

Insulation layer

7th

Rolling elements

8th

Metal sleeve

9

inner part

D.

radial thickness of the insulation layer

E.

radial extension of the bearing ring

a

distance

b

distance

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102013104186 A1 [0002]
• DE 102014224153 A1 [0002]

Claims (10)

Bearing (1) comprising a first bearing ring (2) and a second bearing ring (3), which are arranged rotatably relative to one another, the first bearing ring (2) having a contact surface (4) for contact with a first component and the second bearing ring (3 ) has a contact surface (5) for contact with a second component, characterized in that at least one of the bearing rings (2, 3) has at least one electrically insulating insulation layer (6) which is arranged away from the contact surface (4, 5). Camp after Claim 1 , characterized in that the first bearing ring (2) is an outer bearing ring and the second bearing ring (3) is an inner bearing ring. Camp after Claim 1 or 2 , characterized in that it is a roller bearing in which roller bodies (7) are arranged between the bearing rings (2, 3). Camp after Claim 2 or 3 , characterized in that the insulation layer (6) is arranged in a radial area between 10% and 90% of the radial extent of the bearing ring (2, 3). Camp according to one of the Claims 2 to 4th , characterized in that the insulation layer (6) has a hollow cylindrical shape. Camp according to one of the Claims 2 to 5 , characterized in that the insulation layer (6) has a radial thickness (D) which is between 0.1% and 5% of the radial extension (E) of the bearing ring (2, 3). Camp according to one of the Claims 1 to 6th , characterized in that the insulation layer (6) consists of aluminum oxide, zirconium oxide or titanium carbide. Camp according to one of the Claims 1 to 6th , characterized in that the insulation layer (6) consists of a plastic. Camp according to one of the Claims 2 to 8th , characterized in that a part of the bearing ring (2, 3) adjoining the insulation layer (6) is designed as a hollow cylindrical metal sleeve (8). Camp according to one of the Claims 1 to 9 , characterized in that only the first bearing ring (2), only the second bearing ring (3) or both the first bearing ring (2) and the second bearing ring (3) have at least one insulation layer (6).

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