EP2272138A1 - Multiple brush for slip rings - Google Patents

Abstract

A sliding-contact arrangement or slipring includes a slide-track having a V-shaped groove and also a brush having at least two slide-wires which simultaneously make sliding contact with the V-shaped groove of the slide-track. Furthermore, the two slide-wires have different diameters and contact the slide-track at different angular positions. Thereby an increased tolerance to mechanical vibrations and shocks as well as a reduced contact resistance results.

Description

 Multiple brush for slip rings

Technical area

The invention relates to a device for transmitting electrical signals by means of sliding contacts between mutually movable parts. Such transmission systems are preferably used in linear design or for rotating systems in cylindrical or plate-shaped designs. On a sliding path made of electrically conductive material, a sliding contact or a plurality of sliding contacts grind from a likewise electrically conductive material. Due to the galvanic contact between the sliding tracks and contact electrical current can be transmitted.

State of the art

Sliding contact arrangements are used, for example, in a linear design in cranes or other conveyor systems for transmission between a mobile crane and a stationary control unit. Another application of sliding contacts in a circular design, usually called slip rings, is the transmission between mutually rotatable parts. A typical field of use is, for example, in computer tomographs between the rotor, which carries the X-ray tube and the detector, and a stationary evaluation unit, which processes and displays the image data. In the prior art sliding contacts a sliding contact on a metallic basis, for example, as a wire or thin sheet metal is used especially for small designs.

In US 2,269,614 a sliding contact brush with a plurality of individual wires is disclosed. It is assumed here that at least one wire at a time is always engaged with the grinding path.

US 4,483,574 discloses a sliding contact brush having a plurality of contact wires, which is particularly suitable for use in collectors. The devices are here relatively short, so that they preferably rest vertically on the surface of the collector.

EP 0 662 736 A1 discloses a multiwire brush with two to five wires, which lie side by side in the groove of a grinding path and the wires are in contact with the groove of the grinding path simultaneously.

Presentation of the invention

The object of the invention is to brush the known contact or sliding contact arrangements to further improve that increased transmission reliability and in particular a high insensitivity to mechanical vibration and shocks.

Inventive solutions to this problem are specified in the independent claims. Further developments of the invention are the subject of the dependent claims.

A sliding contact arrangement according to the invention comprises at least one sliding track with a V-groove 5 and at least one multi-wire brush running thereon with at least two sliding wires 3, 4 of different diameter. knife. Essential for the invention is that both sliding wires are electrically connected in parallel with each other and run in the same V-groove of the grinding path. Thus, they are simultaneously in contact with the slideway. For the current to be transmitted, there are thus two current paths simultaneously. By this measure, on the one hand, the contact resistance is reduced and, on the other hand, the tolerance to mechanical shocks or vibrations is substantially increased, since the two sliding wires have different resonance frequencies of their natural resonance. The different resonance frequencies result from the different spring constants and different masses due to the different diameters. Thus, at a certain excitation frequency with high probability only one of the two sliding wires is excited to vibrate, which can lead to short-term contact interruptions. At the same time, however, the other abrasive wire with a different resonant frequency can still maintain contact. According to the invention, the two grinding wires touch the grinding path at different angular positions 8, 9. This results in a further tolerance to mechanical vibrations, since these preferably occur only in one axis. For example, in vehicles, impacts will preferably occur perpendicular to the ground. If a second grinding wire is now arranged in another direction or another axis, it can still maintain the flow of current.

Another sliding contact arrangement according to the invention is constructed similarly to the contact arrangement described above. In this case, however, the two sliding wires 3, 4 can be arranged at the same angular position 8 relative to the grinding path. It is essential, however, that they run on different radii 10, 11 in the V-groove. This results in a reduced abrasion, since the tracks of the contact are at different positions. Of course, this also results due to the different wire diameter increased tolerance to mechanical vibrations. By the arrangement At an angular position results in relation to the first embodiment of the invention shown a much simpler mechanical design.

A further embodiment of the invention consists in that at least two sliding tracks with V-grooves are electrically connected in parallel, and in these run at least two sliding wires with different diameters. Preferably, a sanding wire runs in each sanding path.

A multi-wire brush according to the invention has at least two sliding wires, which have different diameters.

Preferably, the ratios of the diameters of the at least two sliding wires are in a range of 1: 1.2 to 1: 5. Particularly favorable is a ratio of the diameters in a range of 1: 1.5 to 1: 2.

In a further advantageous embodiment of the invention, the at least two sliding wires on different materials.

In a further advantageous embodiment of the invention, at least two sliding wires 3, 4 with different diameters are held in a holding device, for example a sleeve, at one end of the grinding wires. Likewise, they can simply be soldered or squeezed together. They are electrically and mechanically connected to one another by the holding device. But remain the other ends of the sliding wires against each other are movable.

In a further embodiment of the invention, exactly one grinding wire 3 with a larger diameter and one grinding wire 4 with a smaller diameter is provided. In a further embodiment of the invention, a grinding wire 3 with a larger diameter and three sliding wires 4 are provided with a smaller diameter. The larger diameter abrasive wire 3 travels on a path of the smaller radius loop while the smaller diameter loop wires 4 run on a larger radius track of the abrasive path.

Description of the drawings

The invention will be described by way of example below without limiting the general inventive concept by means of embodiments with reference to the drawings.

Fig. 1 shows in a general form schematically a sliding contact arrangement according to the invention.

FIG. 2 shows a further embodiment of a sliding contact arrangement according to the invention.

Fig. 3 shows the sliding wires and the V-groove of a sliding contact arrangement according to the invention in section.

Fig. 4 shows an alternative brush configuration.

Fig. 5 shows a further inventive multi-wire brush in section.

Fig. 6 shows another multi-wire brush in the side view.

Fig. 7 shows an alternative configuration of the invention. Fig. 1 shows a sliding contact arrangement according to the invention. The slideway 1 is here shown cut in the left part perpendicular to its axis of rotation. In the right part of the figure is the top view of the grinding path from a viewing angle perpendicular to the axis of rotation. The axis of rotation runs vertically in the drawing plane. A brush holder 2 holds here two double brushes 3, 4, wherein each double brush consists of a grinding wire, which is held here on the underside of the brush holder. Alternatively, the abrasive wire may also be passed through the brush holder or otherwise have a positive engagement with the brush holder to increase mechanical stability. Each abrasive wire of the dual brushes shown here has two ends 3a, 3b and 4a, 4b, respectively, with each end in contact with the slip path. This results in two contact points with the grinding path for each grinding wire. In principle, however, one-sided brushes can be realized, which have only one grinding wire 3b, 4b, which is in contact with the grinding path at one point. According to the invention, two such brushes are now electrically connected in parallel and are preferably attached to a common brush block 2. Furthermore, the grinding wires of the brushes have different wire diameters.

In principle, according to the invention, the different diameters of the wires result in different mass ratios of the wires and also different spring constants. As a result, the sliding wires also receive different resonance frequencies. A known from the prior art slip ring with brushes of the same diameter has contact interruptions at certain frequencies of mechanical vibrations. Typically, these frequencies are the resonance frequencies or natural frequencies of the individual contact wires. In an embodiment according to the invention, a contact is now always ensured. If, for example, the first grinding wire is excited by mechanical oscillations at a first resonance frequency, then no excitation of the second grinding wire finds it with a other resonant frequency instead. In this case, all the current flows through the assembly through the second loop wire. Accordingly, the reverse case applies to the application of a vibration frequency corresponding to the resonance frequency of the second abrasive wire. In this case, the first loop wire takes over the entire current.

It is particularly advantageous if both the first grinding wire and the second grinding wire run in the same V-groove 5 of a grinding path. For this purpose, the two sliding wires must rest at different contact points 8, 9 on the grinding path. In a flat brush holder, for example in the form of a plate, particularly preferably in the form of a printed circuit board, this also means that the sliding wires with different angles exit from this or are attached thereto.

Fig. 2 shows an arrangement similar to the preceding, wherein, however, abut the contact wires at the same angular position 8 on the grinding path. Due to the different diameters of the contact wires, the contact wires run at different radii of the grinding path. Thus, the larger diameter abrasive wire 3 rides on a wider radius 10 track, and the smaller diameter loop 4 runs on a smaller radius track 11 further inside. While in the previous embodiment, with contact points at different angular positions It must be ensured that a relatively large diameter ratio is selected, so that the two contact wires 3, 4 can simultaneously concern in the V-groove 5. Preferably, there is still a small gap, which is preferably larger than the diameter of the thinner contact wire, between the two contact wires, if they rest against the V-groove. The diameter ratio is preferably in a range of 1: 2 to 1: 5. Another advantage of this arrangement with two contact wires of different diameters in the same V-groove is the lower wear of the V-groove. Due to the different diameters, the grinding wires penetrate at different depths into the V-groove and thus run in different tracks. Overall, this gives a much better utilization with respect to the service life of the V-groove. If grinding wires with the same diameters were used here, they would run in the same path and wear them much faster.

3 shows the two sliding wires from FIG. 2 together with the V-groove in a section along the axis 8. In the V-groove 5, the second wire 4 with the smaller diameter lies closer to the tip of the V above it at a distance the first wire 3 with the larger diameter. Through the two support point of the first wire 4 in the V-groove 5, a line 11 is shown, which runs on a smaller radius of the grinding path than the line 10 through the support points of the first wire 3 with the larger diameter.

Fig. 4 shows an alternative brush configuration. Instead of the brush holder 2 shown in the preceding figures with individual wires 3, 4, a multi-wire brush can be used. This can be arranged with a simple holder so that the two wires 3, 4 are in accordance with the invention in contact with the slideway. Here, for example, the two wires 3, 4 are combined electrically and mechanically by means of a sleeve to form a unit. The connection of the wires takes place only in the sleeve, but not over the length of the wires, so that these wires are still movable at the ends opposite the tube.

In Fig. 5 yet another brush is shown together with the grinding path in section. It has here a first wire 3 with a large diameter and a plurality of second wires 4 with a smaller diameter. Such a brush can also be constructed based on the previously shown brush holders 2.

FIG. 6 shows a simple configuration of the multi-wire brush from FIG. 5. In this case, the wires 3, 4 are combined in a sleeve or another fastening element and electrically and mechanically connected to one another. The connection of the wires takes place only in the sleeve, but not over the length of the wires, so that these wires are still movable at the ends opposite the tube. Such a brush can now be used in a slideway similar to the previously described double brushes. Here are the different wires at the same time in the V-groove of the slideway. Due to the different resonance frequencies, it is always ensured that at least one of the sliding wires is in contact with the grinding path under mechanical vibration stress. Here, too, there is the additional advantageous effect that the life of the arrangement is increased, since the different wires run in different paths.

Fig. 7 shows a further embodiment of the invention in which the two different sliding wires 3, 4 extend in different V-grooves 5, 6 of the slideway, of course, the two V-grooves and the two sliding wires are electrically connected in parallel.

LIST OF REFERENCE NUMBERS

1 sanding track

2 brush holders

3 first wire

4 second wire

5 first V-groove

6 second V-groove

7 sleeve

8 first point of support

9 second point of support

10 line through first points of support

11 line through second points of support

Claims

claims A sliding contact arrangement comprising a sliding track with a V-groove (5) and a brush comprising at least two sliding wires (3, 4) which simultaneously make sliding contact with the V-groove of the sliding track, characterized in that the at least two sliding wires ( 3, 4) have different diameters and at different angular positions (8, 9) with respect to the grinding path touching the grinding path. 2. sliding contact arrangement comprising a sliding track with a V-groove (5) and a brush comprising at least two sliding wires (3, 4), which are simultaneously in sliding contact with the V-groove of the sliding track, characterized in that the at least two sliding wires ( 3, 4) have different diameters and at the same angular position (8) with respect to the grinding path, but at different radii (10, 11) touch the grinding path, so that the grinding wire (3) with the larger diameter on a path of larger radius ( 10) and the smaller diameter abrasive wire (4) runs on a smaller radius track (11). 3. sliding contact arrangement comprising at least two sliding tracks with V-grooves (5, 6) and a brush comprising at least two sliding wires (3, 4), wherein in each case at least one grinding wire is in sliding contact, each with a V-groove of a grinding path, characterized in that the at least two sliding wires (3, 4) different diameters and the at least two sliding wires with the at least two sliding tracks electrically are connected in parallel. 4. Multi-wire brush with at least two grinding wires (3, 4) for one Sliding contact arrangement comprising a sliding track with a V-groove (5), characterized in that the sliding wires (3, 4) have different diameters. 5. sliding contact arrangement according to claim 1 to 3, characterized in that, the ratio of the diameter of the sliding wires (3, 4) in a ratio of 1: 1.2 to 1: 5, preferably at a value of 1: 2. 6. multi-wire brush according to claim 4, characterized in that, the ratio of the diameter of the sliding wires (3, 4) in a ratio of 1: 1.2 to 1: 5, preferably at a value of 1: 2. 7. sliding contact arrangement according to claim 1 to 3, characterized in that the sliding wires (3, 4) comprise different materials. 8. multi-wire brush according to claim 4, characterized in that the grinding wires (3, 4) comprise different materials. 9. multi-wire brush according to claim 4, characterized in that at least two sliding wires (3, 4) are held with different diameters in a holding device at one end of the grinding wires, wherein the grinding wires are electrically and mechanically connected to each other by the holding device and the other ends of the Grinding wires are movable against each other. 10. multi-wire brush according to claim 4, characterized in that, a grinding wire (3) with a larger diameter and a grinding wire (4) is provided with a smaller diameter. 11. A multiwire brush according to claim 4, characterized in that a larger diameter sanding wire (3) and three smaller diameter sanding wires (4) are provided, the larger diameter sanding wire (3) on a path of the sanding web with a smaller radius and the sliding wires (4) with the smaller Run diameter on a track of the grinding path with a larger radius.