DE10304794B4 - Use of an electrically conductive, magnetic fluid - Google Patents

Abstract

use an electrically conductive, magnetic fluid (1), consisting of a non-magnetic and electrically non-conductive carrier liquid (3) containing electrically conductive and magnetic particles (2) in one electrical component (6), the at least two electrical contacts (12, 13), for forming a transmission volume (11), with between the at least two electrical contacts (12, 13) an electrical signal and / or an electrical voltage and / or an electric current transferable is and by means of magnetic forces (14) relative to the at least two contacts (12, 13) is adjustable.

Description

The The present invention relates to a use of an electric conductive, magnetic fluid.

In a variety of electrical applications need to be between multiple electrical Contacts electrically conductive connections are made, for example to an electrical control signal or an electrical voltage or an electrical current between the interconnected To transfer contacts. Above all, dynamic connections, ie connections, are considered. the dependent closed predetermined conditions and opened or changed.

For example be arranged in a switch therein contacts in dependence an operation of the switch connected or disconnected. such Switches can be configured for example as a limit switch, the different Relative positions between the contacts and a connecting element to connect the contacts recognize. For mechanical solutions the connecting element physically contacted with the contacts to make the respective connection. Alternatively, electronic solutions are possible in which the switch For example, inductive, capacitive, optical, ultrasonic or is operated using the reverb effect to the respective desired switching signal to generate.

Other Applications are e.g. Potentiometer, where a collector track is arranged along a resistance path and in which a connecting element connects the collector to the resistor. The connecting element is adjustable along the tracks, wherein the output signal of Potentiometer of the relative position of the connecting element along the tracks depends. For a mechanical solution is the connecting element usually designed as a grinder. Since such solutions are susceptible to wear, Here, too, electrical or electronic solutions are used, the non-contact and thus wear-free work. Potentiometers are needed, for example, for displacement and angle sensors.

dynamic Connections with physical or sliding contacting of the connecting element with the each contact can work Although relatively inexpensive to manufacture, but are susceptible to wear and in terms of long life and reliability of the respective component disadvantageous. In contrast, electronic Systems contactless work, so that virtually no wear occurs. Electronic systems But all are comparatively expensive. Furthermore, can also at Electronic systems ensure high reliability only limited.

From the US 5,769,996 A It is known to produce a liquid, which consists of a non-magnetic carrier liquid and contains electrically conductive particles and ferromagnetic particles, for producing a permanent or static electrical connection between two electrical conductors in a component. The carrier liquid is designed curable. During the manufacturing process, the electrically conductive magnetic liquid is positioned in an uncured state between the contacts to be joined together. By applying a corresponding magnetic field, the particles are aligned so as to set a desired anisotropic conductivity for the curing process. This anisotropic conductivity is quasi "frozen" by the curing of the carrier liquid.

The US 4,732,706 AA shows an electrically conductive ferrofluid mixture used in ferromagnetic seals, damper fluids in shock absorbers, heat transfer fluids in an excitation coil of loudspeakers, storage fluids, ferrous lubricants, and so on.

The JP 07 226316 A shows a mixture in which magnetic particles hen with an electrically conductive coating verse and are arranged in an electrically insulating liquid. The known magnetic, electrically conductive liquid is used in a measuring device to measure a relationship between shear stress and shear rate with applied electric field.

The DE 1 159 071 A shows a magnetically actuated mercury switch, which works with electrically conductive mercury and with an electrically non-conductive, but magnetic powder that is not wetted by mercury. With magnetic fields, the magnetic powder can be aligned between electrical contacts, which indirectly results in a possibility of moving the mercury between the contacts, namely by displacement.

The US 3,289,126 A shows a mercury switch in which the mercury is mixed with carbonized iron particles, whereby the mercury becomes magnetic. By means of electric coils magnetic fields can be built up, which can adjust this magnetic mercury-iron mixture to connect electrical contacts or separate from each other.

The The present invention has the object for dynamic connection to show a way of at least two electrical contacts which is inexpensive and with a high reliability a long lifetime of a system working with it.

These The object is achieved by the objects the independent one claims solved. Advantageous embodiments are the subject of the dependent Claims.

The Invention is based on the general idea, an electrically conductive and magnetic or ferromagnetic fluid in the form of a transfer volume in an electrical component for switching electrical contacts to use, what the transfer volume by means of magnetic forces is adjustable relative to the contacts. Such a CMF (Conductive Magnetic fluid) combines in itself two properties, namely the Influencing by magnetic forces on the one hand and the electrical conductivity on the other hand, in an electrically non-conductive carrier liquid. This makes it possible the CMF by means of magnetic forces, so in particular contactless to manipulate, namely to move the CMF relative to the electrical contacts. hereby can connected to the CMF two or more electrical contacts since the CMF is sufficient according to the invention electrically conductive is. It is also possible the CMF along contacts, for example in a potentiometer, to position. Although it comes here to a physical Contact between the CMF and the respective contacts, but friction coefficients between a liquid and a solid be extremely small. Accordingly, the electrical contacts with the CMF virtually wear-free be contacted.

With The CMF may be provided with a connecting element in the electrical component be provided by means of magnetic forces without contact relative to the respective Contacts can be adjusted. This allows wear-free working Systems are realized that work reliably and have a long service life have.

there is it possible in particular the CMF and the respective contacts in a hermetically sealed casing to accommodate and the housing in such a way that the magnetic forces for adjusting the CMF from the outside through a wall of the housing through the CMF. Open up for the respective components novel fields of application.

Further important features and advantages of the invention will become apparent from the Dependent claims, from the drawings and from the associated description of the figures the drawings.

It it is understood that the above and the following yet to be explained features not only in the specified combination, but also in other combinations or alone, without to leave the scope of the present invention.

preferred embodiments The invention are illustrated in the drawings and in the following description explains where like reference numerals refer to the same or functionally same or similar Refer to components.

It show, in each case schematically,

1 a view of a volume of an electrically conductive, magnetic fluid according to the invention,

2 a view of an electrically conductive particle,

3 a circuit diagram of a potentiometer,

4 a simplified schematic diagram of a potentiometric transducer in a plan view,

5 a longitudinal section through the transducer according to the section lines V in 4 .

6 a cross section through the transducer according to section lines VI in 4 .

7 a cross section as in 6 but in another embodiment of the transducer.

Corresponding 1 contains a volume of an electrically conductive, magnetic fluid according to the invention 1 , in the following also CMF volume 1 called, electrically conductive, magnetic particles 2 in a carrier fluid 3 are distributed. In particular, the particles form 2 and the carrier liquid 3 a dispersion. Basically, the particles can 2 consist of any magnetically attractable, so ferro-magnetic material. It is important that the particles 2 are attractable by magnetic forces. The particles 2 can be soft magnetic or hard magnetic.

In a particular embodiment, the particles 2 consist of a magnetic and electrically conductive material. For example, the particles 2 made of iron or steel or stainless steel.

In another embodiment, the particles 2 a magnetic core 4 having, with an electrically conductive coating 5 is provided. The magnetic core 4 can then consist of an electrically non-conductive material. For example, the cores exist 4 made of ferrite, which serves as base material for the production of magnetic bodies, eg in generators or electric motors. The surface of the cores 4 it does not have to be fully coated, nor do all cores have to 4 with the coating 5 be provided. However, preferred is an embodiment in which the cores 4 be completely coated on its surface and / or in which all cores 4 with the coating 5 are provided. The concentration of the particles 2 in the liquid 3 will depend on the selected electrical conductivity of the CMF volume 1 selected.

The electrical coating 5 the cores 4 can be realized for example with carbon or with a metal, in particular with a more or less noble metal.

It is also possible to provide the magnetic and electrically conductive liquid by using magnetic particles 2 in an electrically conductive carrier liquid 3 are mixed. For example, the carrier liquid contains 3 a corresponding amount of dissolved ions. Likewise, electrically conductive particles 2 in a magnetic carrier liquid 3 be mixed.

The carrier liquid 3 is preferably, however, not electrically conductive, so that the particles 2 are magnetically and electrically conductive. As carrier liquid 3 For example, an oil is suitable. A carrier liquid is advantageous 3 which has a relatively large surface tension. A large surface tension causes a relatively strong cohesion of the CMF volume 1 and acts creep and adhesion of the carrier liquid 3 on a body in contact with it. Particularly advantageous is an embodiment in which as the carrier liquid 3 a non-emigrating oil is used.

For clarification is in 2 a single particle 2 shown that a magnetic core 4 having, on its outside with an electrically conductive coating 5 is provided.

Alternatively, an embodiment is possible in which the preferably magnetically and electrically neutral carrier liquid 3 on the one hand magnetic particles 2 and on the other hand electrically conductive particles 2 contains.

The electrically conductive, magnetic fluid according to the invention 1 can be particularly easily produced by electrically conductive and / or magnetic particles 2 in a carrier liquid 3 be introduced. The electrically conductive and magnetic particles 2 can be made, for example, by using magnetic cores 4 with an electrically conductive coating 5 be provided.

The CMF volume 1 or the electrically conductive, magnetic fluid according to the invention 1 is particularly suitable for use in an electrical component for transmitting an electrical signal and / or an electrical voltage and / or an electrical current between at least two electrical contacts.

In the 3 to 7 is an example of a potentiometer without limiting the generality describes an electrical component in which the inventive electrically conductive magnetic fluid 1 can be used. It is clear that in principle also with other electrical components two or more electrical contacts with the aid of the electrically conductive, magnetic fluid according to the invention 1 can be dynamically connected with each other.

Corresponding 3 has a potentiometer 6 three connections 7 . 8th . 9 as well as a resistor 10 on the one with 8th designated connection with a symbolized by an arrow connecting element 11 can access at different positions, so at different resistance values. Depending on the positioning of the connecting element 11 generates the potentiometer 6 at its connections 7 . 8th . 9 Output signals that can be evaluated in a corresponding circuit.

4 shows an embodiment in which the potentiometer 6 is designed as a linear transducer. The potentiometer 6 contains a resistor track 12 , which forms a first electrical contact, and a collector track 13 which forms a second electrical contact. The connecting element 11 is here by a volume, in particular by a drop, the electrically conductive, magnetic fluid 1 is formed and therefore in the following also as actuating volume 11 or CMF volume 1 designated. The operating volume 11 or the CMF volume 1 is positioned so that the CMF volume 1 both the collector track 13 as well as the resistance track 12 contacted.

This positioning of the CMF volume 1 becomes appropriate 5 with the help of magnetic forces 14 realized that in 5 symbolized by broken lines. The magnetic forces 14 be from an actuator 15 generated. In the embodiment shown here, this actuator 15 an actuator 16 on, which according to arrows 17 relative to the contacts or tracks 12 . 13 of the potentiometer 6 is adjustable. To generate the magnetic forces 14 can the actuator 16 at least one magnet 18 included, which can be configured as a permanent magnet or as an electromagnet.

In a relative adjustment of the actuator 16 relative to the contacts or tracks 12 . 13 becomes a magnetic field affecting the magnetic forces 14 generated, adjusted accordingly with. Because the magnetic forces 14 on the CMF volume 1 act, the drop follows 11 the adjustment movements of the actuator 18 , what in 5 by appropriate arrows 19 is indicated. By adjusting the actuator 18 thus can the positioning of the drop 11 along the tracks or contacts 12 . 13 be changed, resulting in a corresponding manner, the output signal of the potentiometer 6 changes.

Unless the potentiometer 6 can be used as a displacement transducer, the actuator 16 be connected to an object whose relative movements are to be detected with the transducer.

How out 5 clearly shows the contacts 12 . 13 or the resistance path 12 and the collector track 13 as well as the CMF volume 1 in a housing 20 be accommodated that is suitably hermetically sealed to the outside. This case 20 Here is at least one of the tracks or contacts 12 . 13 opposite wall 21 for the magnetic forces 14 permeable. The outside of the case 20 or on the outside of the housing 20 arranged actuator 15 can thus through the wall 21 through to the CMF volume 1 act. Accordingly, causes a relative displacement of the actuator 16 along the outside of the case 20 a corresponding relative adjustment of the CMF volume 1 in the case 20 , Corresponding 5 can the actuator 16 advantageously relative to the housing 20 be positioned so that it is spaced from the housing 20 , so without contact along the housing 20 is adjustable.

The application according to the invention of the electrically conductive, magnetic fluid 1 in the potentiometer 6 to realize the dynamic contacting of the tracks or contacts 12 . 13 leads to minimal friction between the CMF volume 1 and the surface of the contacts or tracks 12 . 13 , The forces for adjusting the CMF volume 1 are therefore very small. Furthermore, wear of the contacts or tracks occurs 12 . 13 and the CMF volume 1 virtually not on, which increases the life and reliability of the potentiometer 6 elevated. Finally, the non-contact arrangement of the actuator also leads 16 relative to the housing 20 to a minimal or missing friction, so that here a wear can be avoided. Another advantage of the overall extremely reduced friction can be seen in the fact that the adjustment of the potentiometer 6 Required adjusting forces are extremely small, so the potentiometer 6 can be designed as a precision instrument.

The resistance track 12 and the collector track 13 can, for example, in the form of a conductive plastic, called Leitplastik, on a substrate 22 be upset. Corresponding 6 are in the substrate 22 two tracks 23 . 24 embedded, one of which to the with 7 designated connection leads and to the resistance path 12 connected. The other trace 24 leads to that 8th designated connection and is with the collector track 13 covered. The resistance track 12 is at the ends to the one with the track 23 and the other with the 9 connected terminal connected.

In the embodiment according to 6 are in the case 20 also longitudinal bars 25 arranged here on the tracks or contacts 12 . 13 support. The longitudinal webs 25 are electrically non-conductive and close a channel between them 26 one in which the CMF volume 1 housed and along the tracks 12 . 13 is adjustable. This is the CMF volume 1 enclosed in a defined space, so that the drop 11 It can also be formed again and again, if it should be shared, for example, by vibrations.

While in the embodiment according to 6 the collector track 13 and the resistance track 12 in a plane next to each other on the substrate body 22 are arranged, shows 7 another embodiment in which the resistance path 12 and the collector track 13 Although together, but in different levels are opposite each other. In this embodiment, the potentiometer 6 comparatively compact to be built, for example, is only a longitudinal ridge 25 to disconnect the channel 26 required. Likewise, the required CMF volume is reduced 1 ,

In the embodiments shown here, the actuator has 15 the actuator 16 which is relative to the contacts or tracks 12 . 13 can be adjusted while the appropriate positioning of the CMF volume 1 causes. In another embodiment, the actuator 15 have a magnetic force generator, which is designed in the manner of a linear motor. This magnetic force generator then extends along one of the CMF volumes 1 predetermined Adjustment path. In the present case, the magnetic force generator would then along the tracks or contacts 12 . 13 extend. The magnetic force generator can then generate magnetic forces that increase the CMF volume 1 along this displacement, ie along the contacts or tracks 12 . 13 drives. Thus, it is possible without relative movement between the actuator 15 and the contacts or tracks 12 . 13 a relative adjustment of the CMF volume 1 to generate in which only a corresponding magnetic field along the tracks or contacts 12 . 13 is positioned.

Other components containing electrical contacts, with the aid of the inventive electrically conductive, magnetic fluid 1 can be contacted dynamically, for example, a potentiometer as in the 4 to 7 which is additionally equipped with one or more switches, a switch, a sealed switch, a limit switch, a proximity switch, a tap changer, an incremental encoder, an absolute encoder, a relay, a sealed relay and so on.

Claims (26)

Use of an electrically conductive, magnetic fluid ( 1 ), consisting of a non-magnetic and electrically non-conductive carrier liquid ( 3 ), the electrically conductive and magnetic particles ( 2 ), in an electrical component ( 6 ), which has at least two electrical contacts ( 12 . 13 ), to form a transmission volume ( 11 ), between which the at least two electrical contacts ( 12 . 13 ) an electrical signal and / or an electrical voltage and / or an electric current is transferable and by means of magnetic forces ( 14 ) relative to the at least two contacts ( 12 . 13 ) is adjustable. Use according to claim 1, characterized in that the carrier liquid ( 3 ) electrically conductive particles ( 2 ) and magnetic particles ( 2 ) contains. Use according to claim 1, characterized in that the carrier liquid ( 3 ) electrically conductive magnetic particles ( 2 ) contains. Use according to claim 3, characterized in that the electrically conductive, magnetic particles ( 2 ) an electrically conductive coated magnetic core ( 4 ) exhibit. Use according to claim 4, characterized in that the magnetic cores ( 4 ) consist of an electrically non-conductive material. Use according to claim 4 or 5, characterized in that the magnetic cores ( 4 ) consist of ferrite. Use according to one of claims 4 to 6, characterized in that the magnetic cores ( 4 ) are coated with carbon or with a metal. Use according to one of claims 1 to 7, characterized in that the carrier liquid ( 3 ) is an oil. Use according to one of claims 1 to 8, characterized in that the carrier liquid ( 3 ) has a relatively large surface tension. Use according to claims 8 and 9, characterized in that the carrier liquid ( 3 ) is a non-migrating oil. Electrical component, in particular switch or potentiometer ( 6 ), - the component ( 6 ) at least two electrical contacts ( 12 . 13 ), wherein the component ( 6 ) for transmitting an electrical signal and / or an electrical voltage and / or an electric current between two of the contacts ( 12 . 13 ) a transmission volume ( 11 ) of an electrically conductive, magnetic fluid ( 1 ), wherein the electrically conductive, magnetic fluid ( 1 ) of a non-magnetic and electrically non-conductive carrier liquid ( 3 ), the electrically conductive and magnetic particles ( 2 ), the component ( 6 ) an actuating device ( 15 ), which when actuated, the transmission volume ( 11 ) by means of magnetic forces ( 14 ) relative to the contacts ( 12 . 13 ) adjusted. Component according to claim 11, characterized in that - the contacts ( 12 . 13 ) and the transmission volume ( 11 ) in a hermetically sealed housing ( 20 ) are arranged, - that the actuating device ( 15 ) on the outside of the housing ( 20 ) or outside the case ( 20 ) is arranged, - that at least one wall ( 21 ) of the housing ( 20 ) for the magnetic forces ( 14 ) of the actuating device ( 15 ) is permeable. Component according to claim 11 or 12, characterized in that the actuating device ( 15 ) an actuator ( 16 ), the at least one magnet ( 18 ) for generating the magnetic forces ( 14 ) and along one for the actuating volume ( 11 ) predetermined displacement relative to the contacts ( 12 . 13 ) is adjustable. Component according to claims 12 and 13, characterized in that the actuator ( 16 ) contactlessly along the housing ( 20 ) is adjustable. Component according to claim 11 or 12, characterized in that the actuating device ( 15 ) has a magnetic force generator, which is designed in the manner of a linear motor, along one for the actuating volume ( 11 ) predetermined Verstellwegs and for generating the actuating volume ( 11 ) along the displacement driving magnetic forces ( 14 ) serves. Component according to one of claims 11 to 15, characterized in that - the component is a potentiometer ( 6 ) whose collector track ( 13 ) and resistance track ( 12 ) each form a contact, - that collector track ( 13 ) and resistance track ( 12 ) are arranged contactlessly together, - that the actuating volume ( 11 ) Collector track ( 13 ) and resistance track ( 12 ), that - with the actuating device ( 15 ) the relative position of the transfer volume ( 11 ) along the collector track ( 13 ) and along the resistance path ( 12 ) is adjustable. Component according to one of claims 11 to 16, characterized in that the component ( 6 ) is a member of the following group of components: potentiometer, sealed potentiometer, potentiometer with integrated switch, switch, sealed switch, limit switch, proximity switch, tap changer, incremental encoder, absolute encoder, relay, sealed relay. Component according to one of claims 11 to 17, characterized in that the carrier liquid ( 3 ) electrically conductive particles ( 2 ) and magnetic particles ( 2 ) contains. Component according to one of claims 11 to 17, characterized in that the carrier liquid ( 3 ) electrically conductive magnetic particles ( 2 ) contains. Component according to Claim 19, characterized in that the electrically conductive, magnetic particles ( 2 ) an electrically conductive coated magnetic core ( 4 ) exhibit. Component according to claim 20, characterized in that the magnetic cores ( 4 ) consist of an electrically non-conductive material. Component according to claim 20 or 21, characterized in that the magnetic cores ( 4 ) consist of ferrite. Component according to one of claims 20 to 22, characterized in that the magnetic cores ( 4 ) are coated with carbon or with a metal. Component according to one of claims 11 to 23, characterized in that the carrier liquid ( 3 ) is an oil. Component according to one of claims 11 to 24, characterized in that the carrier liquid ( 3 ) has a relatively large surface tension. Component according to Claims 24 and 25, characterized in that the carrier liquid ( 3 ) is a non-migrating oil.