EP2721696A1

EP2721696A1 - Wire for sliding contacts and sliding contacts

Info

Publication number: EP2721696A1
Application number: EP12732967.0A
Authority: EP
Inventors: Reinhold Weiland; Thomas Hild; Patrick Baake; Harald Manhardt; Bernd Gehlert
Original assignee: Heraeus Materials Technology GmbH and Co KG
Current assignee: Heraeus Deutschland GmbH and Co KG
Priority date: 2011-06-15
Filing date: 2012-06-12
Publication date: 2014-04-23
Anticipated expiration: 2032-06-12
Also published as: DE102011106518B4; EP2721696B1; WO2012171632A1; US20140120743A1; DE102011106518A1; CN103608976A; CN103608976B

Abstract

The invention relates to a wire for producing a sliding contact, wherein at least an inner core of the wire comprises a copper/silver alloy. The invention also relates to a sliding contact with at least one such wire, wherein a mating contact is provided, with at least one of the wires resting on the conductive surface of said mating contact, wherein the spring force of the wire on the conductive surface of the mating contact brings about electrical contact between the wire and the mating contact, and the mating contact is moveable towards the wire, with the result that the surface of the wire slides over the mating contact during a movement of the mating contact. Finally, the invention also relates to a potentiometric sensor, a potentiometer, a sliding controller, a position sensor, a rotary switch, an electric motor, a generator, a wind turbine, a slip ring system, a servo drive or a current collector with such a sliding contact.

Description

Wire for sliding contacts and sliding contacts

The invention relates to a wire for producing a sliding contact. The invention also relates to a sliding contact with such a wire.

Finally, the invention relates to a potentiometric sensor, potentiometer, slider, position sensor, rotary switch, electric motor, generator, wind turbine, slip ring system, actuator or pantograph with such a sliding contact. Wires for sliding contacts and sliding contacts themselves find a variety of applications when power is to be transferred to moving parts. Sheathed wires with an inner core of a first metal, or of a first metallic alloy, and a sheath or a coating of a second metal or a second metallic alloy are also used. Such jacket wires are used for example as sliding contacts in Schleifringübertragersystemen. These are used to transmit signal and power currents in rotating systems, such as wind turbines or robot arms.

Sliding contacts are known for example from DE 40 20 700 A1. DE 199 13 246 A1 discloses a grinder for transmitting electrical signals, which is designed as a multi-wire grinder. The multiplicity of contacts should ensure a continuous electrical contact. From EP 0 054 380 A2 a tuft contact with a slip ring is known as a sliding contact, which consists of a plurality of individual wires. The trend in slip ring systems is towards higher currents. At the same time, efforts are increasingly being made to reduce expensive precious metals.

From DE 10 2004 028 838 A1 discloses a sliding contact with a base body made of a wire is known in which a sliding contact body is arranged at one end of the wire. In this way, it is possible for the main body of the contact an inexpensive, resilient material,

CONFIRMATION COPY such as to choose stainless steel, while the energy transferring part as a sliding contact body from another, optimized for energy transfer material may consist. It is advantageous that expensive precious metal can be saved because not the entire spring contact must be made of a precious metal or a noble metal alloy. The disadvantage of this is the higher cost of producing such a sliding contact compared to the use of a simple wire.

A preferred material used for the construction of wires for sliding contacts are copper beryllium alloys, in particular CuBe ₂ , which are gladly used because of their good elastic properties. It is also known to use cladding wires having a core of a copper-beryllium alloy and a shell of a noble metal or a noble metal alloy. These sheath wires have due to the cured Cu Be ₂ -Kem good spring properties. Also, the contact resistance and corrosion resistance of these sheath wires are very good due to a typically high gold-containing sheath.

The disadvantage of this is that the copper-beryllium alloy has a poor electrical conductivity compared to pure copper. As a result, the current carrying capacity of such a wire or a coated wire with a core of a copper-beryllium alloy is comparatively low. To transmit higher currents, either the diameters of the wires or the number of wires must be increased. Both measures are associated with significant additional costs due to the higher use of precious metals in the jacket or the coating. Beryllium and beryllium alloys such as CuBe ₂ are also increasingly avoided due to their environmental impact.

The object of the invention is therefore to overcome the disadvantages of the prior art. In particular, a wire and a sliding contact with such a wire is to be provided, which has a higher conductivity, but at the same time still has sufficiently good elastic properties, which are necessary for a sliding contact. Particularly preferred would be a wire that manages without polluting beryllium. Further, it would be advantageous if the manufacturing cost of such a wire and thus a sliding contact constructed with such a wire could be reduced.

The object of the invention is achieved in that at least one inner core of the wire consists of a copper-silver alloy.

Due to its electrical and mechanical properties, the copper-silver alloy makes it possible to build up a thin, well-conductive spring contact. It can be provided that the inner core extends along the entire length of the wire.

It can also be provided according to the invention that the wire is an elastic wire with a round or an angular cross-section. Wires are easy to get. With a round cross section of the wire, this has a symmetrical elasticity, so that a mating contact of a sliding contact, which is constructed with such a wire, may also be uneven.

Particularly advantageous wires according to the invention are characterized in that the copper-silver alloy has up to 30 wt .-% silver, preferably 1 to 25 wt .-% silver, more preferably 5 to 15 wt .-% silver, most preferably 10% by weight of silver.

In these mixtures, the mechanical and electrical properties are particularly well suited to construct wires according to the invention. This applies in particular to the electrical conductivity of the copper-silver alloy (Cu-Ag alloy) and the elastic properties, that is, above all, the elastic modulus of the Cu-Ag alloy. The wires are then particularly well suited for sliding contacts according to the invention. The proportion of silver is given here in percent by weight (wt .-%).

It can also be provided that the copper-silver alloy contains small admixtures of other elements with a proportion of less than 4 wt .-%, in particular Zr and / or Cr, preferably with a proportion of less than 1 wt .-%, particularly preferably with a proportion of less than 0.1 wt .-%.

For example, a slight addition of chromium (Cr) but also zirconium (Zr) can simplify the application of a gold alloy as a coating, or ensure that a gold alloy holds better on the surface of the wire.

According to a further embodiment of the invention can be provided that the wire is extended and has a cross section between 0.1 mm and 4 mm.

Furthermore, it can be provided that the wire has a thickness of 0.1 mm to 3 mm, preferably a thickness of 0.15 mm to 2 mm.

According to a further embodiment of the invention can be provided that the wire is a wound endless wire or has a length of 10 mm to 300 mm, preferably one Length of 20 mm to 180 mm, more preferably has a length of 30 mm to 100 mm.

Wires with a length between 10 mm and 300 mm are particularly easy to install in sliding contacts according to the invention. By providing wires of suitable length, manual trimming of an endless wire is avoided. Therefore, cut wires for sliding contacts are particularly preferred.

A very particularly preferred embodiment of the invention provides that the wire comprises a coating of a noble metal alloy, preferably a coating of a gold alloy, more preferably of a gold alloy comprising silver, copper and / or palladium, most preferably of an alloy containing 70% by weight of gold, 20% by weight of silver and 10% by weight of copper and / or palladium.

The coating has the effect that the surface of the wire is not oxidized and thus a low contact resistance of such a wire to a mating contact is ensured in the long term. With the core of the wire made of a copper-silver alloy, the surprising combinatorial effect that results from the smaller wire cross-section due to the better electrical conductivity of the copper-silver core, a smaller amount of precious metal for coating the wire use. This saves costs when building the wire. In addition, the Cu-Ag core is particularly good and easy to coat with the specified gold alloys. The durability of such a coating on the Cu-Ag alloy is particularly good, especially in silver-containing gold alloys.

It can also be provided that the coated wire comprises a chromium-containing intermediate layer between the core and the coating.

This achieves a further improvement in the durability of the coating on the core.

In the invention wires of coating can be provided that the coating is a galvanic coating, preferably with a layer thickness of 0.1 to 20 ^{η μι} μπι, particularly preferably with a layer thickness of 0.5 to μιτι μητι. 2

Alternatively, it can be provided that the coating is a mechanically applied cladding coating, so that the wire is a cladding wire, preferably with a layer thickness of 5 μιη to 50 μηι, more preferably with a layer thickness of 10 μιτι to 25 μ ^η η. Coated wires may also be characterized in that the coating is a cylinder jacket that extends around the cylindrical core of the wire.

Furthermore, it can be provided that the coating of the wire is applied by roller cladding, sputtering or galvanically applied to the base body. Uncoated wires can be distinguished according to the invention in that the wire consists of the copper-silver alloy. The wire is then a massive copper-silver wire, which also works without an outer coating.

The object of the invention is also achieved by a sliding contact with at least one such wire, wherein a mating contact is provided, rests on the conductive surface of at least one of the wires, wherein the spring force of the wire on the conductive surface of the mating contact an electrical contact between the Wire and the mating contact causes and the mating contact is movable against the wire, so that the surface of the wire grinds during a movement of the mating contact on the mating contact.

It can be provided that the mating contact is rotatably mounted and the conductive surface of the mating contact is at least partially rotationally symmetrical.

It can further be provided that the sliding contact is a multi-wire grinder with a plurality of electrically contacted wires.

Multiwire grinders are particularly suitable because they can handle the failure of individual contacts and can adapt well to the profile of a mating contact. It can also be provided that the sliding contact is formed such that at least one of the wires rests with its coating on the mating contact.

The object of the invention is also achieved by a potentiometric sensor, potentiometer, slider, position sensor, rotary switch, electric motor, generator, wind turbine, slip ring system, actuator or pantograph with such a sliding contact. The object of the invention is finally solved by a potentiometric sensor, a potentiometer, a slider, a position sensor, a rotary switch, an electric motor, a generator, a wind turbine, a slip ring system, an actuator or a current collector with such a wire as a sliding contact. In such components, the wires and sliding contacts according to the invention can be used particularly effectively.

The invention is based on the surprising finding that the material used, namely the copper-silver alloy, is a highly conductive material, which allows the transmission of higher currents with constant cross section, or allows the transmission of constant currents at a smaller cross section, and the Alloy at the same time has suitable mechanical properties, such as the elasticity has to form a spring contact.

If the wire is formed as a sheathed wire or as a coated wire, which comprises a core of such a copper-silver alloy, results from the constant cross section at higher currents, or from the smaller cross section at constant currents, the surprising combinatorial advantage that the coat constructed mostly of expensive precious metals or the coating has a smaller cross-section and therefore less of the expensive jacket material or the coating must be consumed for the production of such a jacket wire or coated wire. This leads to a significant cost reduction in the production of such a cladding wire or coated wire, especially for thicker coatings such as cladding wires. Thus, a corresponding precious metal savings is so connected especially in a mantle wire. Due to the significantly higher electrical conductivity of Cu-Ag materials compared to CuBe ₂ , the use of a Cu-Ag alloy wire or a coated wire or a cladding wire with a Cu-Ag core enables the transmission of considerably higher electric currents constant wire cross section. Conversely, a wire with a smaller cross section can be used to transmit comparable currents.

The replacement of CuBe ₂ by Cu-Ag for wires for sliding contacts can meet the demand of the market for beryllium-free products. Beryllium is suspected to have harmful environmental effects, so there is a need for beryllium-free products.

Cu-Ag-based wires according to the invention can be used in sliding contacts according to the invention, such as slip ring transmission systems. Such slip ring transmitters are essentially used for transmitting electrical signals and electrical power in wind turbines. energy systems are used. Generally, slipring assemblies are used wherever electrical currents are to be transferred between rotating and static parts, such as robot arms.

Exemplary embodiments of the invention will be explained below with reference to three schematically illustrated figures, without, however, limiting the invention. Showing:

Figure 1: a schematic side view of a sliding contact according to the invention;

Figure 2 is a schematic perspective view of a wire according to the invention and

Figure 3: a schematic view of an alternative sliding contact according to the invention.

Figure 1 shows a schematic side view of a sliding contact 1, which is constructed with a wire 2 according to the invention. The wire 2 is either made of solid copper-silver alloy or it comprises a core of such an alloy and is coated on its outer surface with a gold alloy. The copper-silver alloy conducts the current and provides sufficient elasticity of the wire 2.

The wire 2 is fixed with a fixation 3 on a device 4. The device 4 may be any equipment, such as the mast of a wind turbine or a part that is fixedly connected to the mast of a wind turbine. On the device 4, a suspension 5 is arranged, which is fixedly connected to the device 4. In the suspension 5, a roller 6 is mounted as a counter contact to the wire 2 rotatable about an axis 7. The roller 6 has a conductive surface and is cylindrically shaped. The axis 7 is at the same time the axis of symmetry of the cylindrical roller 6. The roller 6 is connected via the suspension 5 is not electrically connected to the device 4.

The wire 2 is fixed relative to the roller 6 so that it is pressed onto the roller 6. As a result, the wire 2 is elastically deformed. As the roller 6 rotates in the suspension 5, the surface of the wire 2 grinds over the conductive cylinder shell of the roller 6. By the continuous contact which the wire 2 generates with the rotating roller 6, current can flow from the wire 2 be transferred to the roller 6 or vice versa. By the spring force of the wire 2, the contact with the surface of the roller 6 is maintained.

On the wire 2, an electrical line 8 is connected, with the current to further components (not shown) or can be passed from other components to the wire 2. The wire 2 having a core made of a copper-silver alloy or made entirely of a copper-silver alloy can be made smaller in diameter than conventional wires for conventional sliding contacts to transmit the same current. Therefore, such a wire 2 is less expensive to manufacture and consumes less resources. The wire 2 can be easily manufactured and does not cause any problems in disposal or reprocessing. Finally, the wire 2 comes out completely without beryllium, which meets newer environmental requirements.

As the wire 2, a wire may be used as shown in Fig. 2 and described below. Figure 2 shows a schematic perspective view of a wire 12 according to the invention for sliding contacts, as shown for example in Figures 1 and 3. The wire 12 shown is a cladding wire 12 having a core 19 made of a copper-silver alloy. The jacket wire 12 is round in cross section. The round surface of the core 19 is surrounded by a jacket 20, which forms a cylindrical coating of the core 19. The sheath 20 is made of a gold alloy, which consists of over 50 wt .-% of gold. The jacket 20 is mechanically applied to the core 19. Alternatively, the wire 12 may also be coated with a thin layer of such a gold alloy.

The coating 20 may be applied to the copper-silver core 19 of the wire 12 by roll plating, by sputtering, or by electroplating. In order to achieve better durability of the coating 20 on the core 19 of the wire 12, an intermediate layer (not shown) may be provided between the core 19 and the coating 20. The intermediate layer can be, for example, a chromium alloy which is applied to the core 19 by electroplating or by vapor deposition.

FIG. 3 shows a schematic view of an alternative sliding contact 21 according to the invention. The sliding contact 21 is constructed with a multiplicity of wires 22 according to the invention and thus forms a multi-wire grinder or a brush contact. The wires 22 are held by a fixing 23. The fixation 23 positions the wires 22 so as to be spaced apart from a metallic rail 26 that is smaller than the portion of the length of the wires 22 that protrude from the fixation 23. As a result, the wires 22 are pressed onto the metallic rail 26 and thereby deform elastically. By the spring force of the wires 22 these are always ge ^¬ presses on the rail 26, which forms the counter-contact to the wires 22nd Via a line 28 are the Wires 22 of the sliding contact 21 electrically contacted. A current may be transmitted from the rail 26 via the wires 22. As the wires 22 move across the rail 26, power can always be transferred from the rail 26 to the wires 22.

The wires 22 comprise a copper-silver alloy and therefore can be made smaller than wires for conventional sliding contacts. As a result, on the one hand less material is consumed and on the other hand smaller structures can be realized. This is advantageous with increasing miniaturization of many components. The sliding contact 21 shown can be realized, for example, in a model railway, as shown in Figure 3.

Wires 22, in particular wires, as illustrated in FIG. 2 and explained in the description of this, can be used as wires 22.

It has been found that copper-silver alloys containing up to 25% by weight of silver and the balance of copper are particularly well suited for constructing a wire 2, 12, 22 according to the invention for a sliding contact 1, 21 according to the invention. In addition, small amounts (less than 4% by weight) of other metals may be included in the alloy. Suitable small admixtures may be, for example, chromium or zirconium.

The features of the invention disclosed in the foregoing description, as well as the claims, figures and embodiments may be essential both individually and in any combination for the realization of the invention in its various embodiments.

LIST OF REFERENCE NUMBERS

1, 21 sliding contact

2, 12, 22 wire

3, 23 fixation

4 device

5 suspension

6 roller / counter contact

7 hub / axle

8, 28 line

19 core

20 coat

26 rail / counter contact

Claims

claims

1. wire (2, 12, 22) for producing a sliding contact (1, 21), characterized in that

at least one inner core (19) of the wire (2, 12, 22) consists of a copper-silver alloy.

2. wire (2, 12, 22) according to claim 1, characterized in that

the inner core (19) extends along the entire length of the wire (2, 12, 22). 3. wire (2, 12, 22) according to claim 1 or 2, characterized in that

the copper-silver alloy has up to 30% by weight of silver, preferably from 1 to 25% by weight of silver, more preferably from 5 to 15% by weight of silver, most preferably 10% by weight of silver. 4. Wire (2, 12, 22) according to any one of claims 1, 2 or 3, characterized in that the copper-silver alloy small admixtures of other elements with a share below 4 wt .-%, in particular Zr and / or Cr contains, preferably in a proportion of less than 1 wt .-%, more preferably in a proportion of less than 0.1 wt .-%. 5. Wire (2, 12, 22) according to one of the preceding claims, characterized in that

the wire (2, 12, 22) has a thickness of 0.1 mm to 3 mm, preferably a thickness of 0.15 mm to 2 mm. 6. Wire (2, 12, 22) according to one of the preceding claims, characterized in that

the wire (2, 12, 22) is a wound endless wire or has a length of 10 mm to 300 mm, preferably has a length of 20 mm to 180 mm, more preferably has a length of 30 mm to 100 mm.

7. wire (2, 12, 22) according to one of the preceding claims, characterized in that

the wire (2, 12, 22) comprises a coating (20) of a noble metal alloy, preferably a coating (20) made of a gold alloy, particularly preferably made of a gold alloy comprising silver, copper and / or palladium, most preferably an alloy containing 70% by weight of gold, 20% by weight of silver and 10% by weight of copper and / or palladium.

Wire (2, 12, 22) according to claim 7, characterized in that

the coating (20) is a galvanic coating (20), preferably with a layer thickness of 0.1 μm to 20 μm, particularly preferably with a layer thickness of 0.5 μm to 2 μm.

Wire (2, 12, 22) according to claim 7, characterized in that

the coating (20) is a mechanically applied cladding coating (20), so that the wire (2, 12, 22) is a cladding wire (12), preferably with a layer thickness of 5 μm to 50 μm, particularly preferably with a layer thickness of 10 pm to 25 pm.

Wire (2, 12, 22) according to any one of claims 7 to 9, characterized in that the coating (20) is a cylinder jacket which extends around the cylindrical core (19) of the wire (2, 12, 22).

Wire (2, 12, 22) according to one of claims 1 to 6, characterized in that the wire (2, 22) consists of the copper-silver alloy.

Sliding contact (1, 21) with at least one wire (2, 12, 22) according to one of the preceding claims, characterized in that

a mating contact (6, 26) is provided, on the conductive surface of at least one of the wires (2, 12, 22) abuts, wherein the spring force of the wire (2, 12, 22) on the conductive surface of the mating contact (6, 26) causes electrical contact between the wire (2, 12, 22) and the mating contact (6, 26) and the mating contact (6, 26) against the wire (2, 12, 22) is movable, so that the surface of the wire ( 2, 12, 22) during a movement of the mating contact (6, 26) via the mating contact (6, 26) grinds.

13. sliding contact (1, 21) according to claim 12, characterized in that

the mating contact (6) is rotatably mounted against the wire (2, 12, 22) and the conductive surface of the mating contact (6) is at least partially rotationally symmetrical. Sliding contact (1, 21) according to claim 12 or 13, characterized in that the sliding contact (21) is a multi-wire grinder (21) having a plurality of electrically contacted wires (2, 12, 22).

Sliding contact (1, 21) according to any one of claims 12, 13 or 14 with at least one wire (2, 12, 22) according to one of claims 7 to 10, characterized in that the sliding contact (1, 21) is formed such that at least one of the wires (2, 12, 22) rests with its coating (20) on the mating contact (6, 26).

Potentiometric sensor, potentiometer, slider, position sensor, rotary switch, electric motor, generator, wind turbine, slip ring system, actuator or pantograph with a sliding contact (1, 21) according to any one of claims 12 to 15.