DE102012204829B4 - Slip ring brushes in press-fit technology, brush holder, brush block and slip ring arrangement as well as method for assembling the slip ring brush - Google Patents

Abstract

Slip ring brush (41, 42) comprising at least one brush wire (39), characterized in that the slip ring brush (41, 42) comprises a press-in mandrel (30) which comprises a mandrel head (32) and/or a structure for pressing into a bore (21) of a brush holder (20) and a bore (31) for receiving the at least one brush wire (39).

Description

Technical area

The invention relates to a slip ring brush and a corresponding holder for a slip ring brush. Slip ring brushes are used in slip ring arrangements for transmitting electrical signals between counter-rotating parts. At least one slip ring brush, made of an electrically conductive material, slides on a sliding track made of electrically conductive material. Electrical current can be transmitted through the galvanic contact between the sliding track and the slip ring brush.

State of the art

In the EP 0 662 736 A1 A multifiber brush with a plurality of brush wires is disclosed, in which the individual brush wires are soldered into a sleeve. Several of these sleeves are soldered into a carrier. This creates several electrical contact points connected in series in the form of soldered connections. This results in a complex structure and a high susceptibility to interference.

The US 3 316 519 A also discloses a multifiber brush in which the individual wires are soldered into a brass body. Here, only one soldering point is in the current path. Furthermore, the deep penetration of the individual brush wires into the brass body and the relatively solid soldering point provide good mechanical relief. The disadvantages here are the complex structure and relatively high cost of the brass body. Furthermore, parallel connection of multiple brushes is only possible with external wiring.

In the EP 1 453 155 A2 A slip ring brush is disclosed in which individual wires are soldered to the surface of a circuit board. This allows for a simple parallel connection. A disadvantage is the high susceptibility to interference due to the mechanically stressed solder joints. Furthermore, this arrangement is not suitable for the use of multifiber brushes, which have significantly better transmission properties than individual brushes.

In the JP 2009 - 205 984 A A slip ring and a method for manufacturing the same are disclosed. Wire brushes are directly contacted by a connecting wire and held in a brush holder by means of an insulating sleeve.

The DE 74 09 677 U discloses an electrical DC machine in which the brush holders are fastened centrally to the brush holder ring by means of screws by means of a brush bolt inserted in an insulated manner into a flange.

In the US 3,488,842 A A method for manufacturing electrical precision brushes is disclosed. Here, individual brush wires are inserted into a HOIse, which is secured in an insulated carrier.

WO 2009/023412 A1 discloses high-current microfiber brushes. The brush fibers are connected to an electrical connector and kept insulated from each other.

In the DE 696 20 532 T2 discloses a brush holder for an electric motor in which brushes made of an elongated flexible substrate with a conductive layer are attached by barbed tongues.

The DE 10 2007 032 991 A1 discloses a sliding contact device for potential dissipation on a machine tool spindle.

The DE 201 15 215 U1 discloses a power transmission element for electrical power and/or data current transmission between a rotor and a stator.

Description of the invention

The invention is based on the object of designing a slip-ring brush and a holder for slip-ring brushes, wherein one or more brush wires should be usable in a single brush, a simple parallel connection of several brushes should be possible, and increased reliability should be achieved with reduced manufacturing costs. Furthermore, particularly simple assembly should be achieved.

This object is achieved by a device according to claim 1. Advantageous embodiments of the invention are specified in the subclaims.

A slip ring brush according to the invention comprises a press-in mandrel with a means, preferably a bore for receiving at least one brush wire, preferably several brush wires, as well as a mandrel head for pressing into a brush holder. The mandrel head is preferably made of a harder material than the brush block. The brush wires are preferably connected to the press-in mandrel within the bore by crimping in a mechanically strong and electrically conductive manner. To mount the slip ring brush in a brush holder, the brush is inserted into a bore in the brush holder. Then, using blind rivet pliers or another suitable tool, the insertion The mandrel can be pulled into the brush holder or pressed in from the opposite side using a pressing tool. This pressing process creates a positive fit between the brush and the bore of the brush block. In order to improve the adhesion of the mandrel in the brush block, the mandrel can optionally have a surface structure and/or the brush block or a bore in the brush block can additionally have a surface structure. The brush particularly preferably has knurling and/or grooves. Alternatively and/or additionally, the mandrel head can also have a corresponding structure, for example rings or grooves, which improve the positive fit with the brush block. In principle, the brush holder can also be a printed circuit board into which at least one brush can be pressed. Alternatively and/or additionally, the at least one brush can also be soldered into a printed circuit board. A 180° brush arrangement can also be realized by parallel pressing into a printed circuit board.

It is particularly advantageous if a predetermined breaking point is provided in order to cut off a part of the mandrel that protrudes beyond the bore of the brush block.

The essential subject matter of this invention is a brush that can be or is fastened in a brush holder by means of a press-in mandrel, wherein the press-in mandrel simultaneously serves to hold the at least one brush wire. In principle, various types of brush wires can be connected to the press-in mandrel. In a particularly simple embodiment, this is a single brush wire. Alternatively, multifiber brushes or tufted brushes can also be connected to the press-in mandrel. Some examples of fastening the at least one brush wire are given below, but these are not exhaustive. Preferably, the at least one brush wire is fastened in the bore of the mandrel by crimping. In special cases, a soldered connection of the at least one brush wire to the bore would also be possible. However, this has the previously described disadvantages of a mechanically stressed solder joint. In a further embodiment, the press-in mandrel could have a longitudinal slot in the region of the bore to enable a spring effect. Thus, the at least one brush wire could be clamped in a force-fitting manner.

The advantage of the slip ring brushes according to the invention over the prior art is their particularly simple design and easy and error-tolerant assembly. The position of the slip ring brushes within the brush holder is precisely defined by the bore in the brush holder. Assembly errors are virtually eliminated. Adjustment of the mounted brush is neither possible nor necessary. This eliminates adjustment errors, which frequently occur with prior art slip ring brushes. The manufacture of the slip ring brushes themselves is also particularly simple, as they consist of only a few simply shaped individual parts. The electrical and mechanical connection between the slip ring wires and the press-in mandrel is preferably achieved by a clamp connection, which is mechanically robust and, in particular, vibration-resistant, as well as providing excellent, long-term stability of high electrical conductivity. The connection between the press-in mandrel and the brush holder is created with a high contact force caused by the pressing-in process. This connection is therefore also long-term stability, vibration-resistant, robust, and provides high conductivity. The problems associated with mechanically stressed solder joints known from the prior art do not occur here.

A further subject matter of the invention is a slip ring brush that can be pressed into a brush holder. Such a slip ring brush has a press-in mandrel that can be pressed into the brush holder. For this purpose, the press-in mandrel preferably comprises a harder material than the material of the brush holder. Furthermore, the brush holder preferably has a structure and/or a thickened portion such that it can be pressed into a bore in the brush holder and forms a positive connection therewith. The brush can be pressed into the brush holder both by pressure from the brush side and by tension from the opposite side.

Another subject of the invention is a brush holder for holding at least one of the slip-ring brushes described herein. Since the slip-ring brushes are connected to the brush holder by press-fitting, the brush holder only requires a suitable bore. This results in a multitude of new degrees of freedom in the design of brush holders compared to the prior art. In a particularly simple embodiment, the brush holder is a metal plate, a metal angle, or another simply shaped component. A brush holder can, for example, preferably be manufactured as a milled part, as a bent sheet metal part, or even as a cast part. Due to the simple assembly of the slip-ring brushes, they can now also be arranged at different angles to one another on the brush holder. This allows, for example, an arrangement of at least two slip-ring brushes at an angle to one another, preferably at an angle of 90°, which is particularly space-saving and thus enables a high packing density.

Another aspect of the invention relates to a brush block with at least one brush holder and at least one slip ring brush. For this purpose, several brush holders with slip ring brushes are arranged on a carrier plate. The carrier plate is preferably made of an insulating material. Alternatively, a carrier plate made of electrically conductive material could be used, which causes the brush holders to be connected in parallel with the slip ring brushes. This allows for increased current carrying capacity.

Finally, the invention relates to a method for inserting one of the slip ring brushes described herein by pulling or pressing the mandrel into the brush holder.

Description of the drawings

• 1 zeigt eine Schleifringbürste in einem Bürstenhalter montiert
• 2 zeigt eine Schleifringbürste im Schnitt
• 3 zeigt eine Schleifringbürste mit Riffelung
• 4 zeigt eine Schleifringbürste mit glattem Schaft
• 5 zeigt eine weitere Schleifringbürste
• 6 zeigt eine Schleifringanordnung
• 7 zeigt eine perspektivische Ansicht der Schleifringanordnung
• 8 zeigt eine Schleifringanordnung mit zwei im Winkel zueinander angeordneten Schleifringbürsten
• 9 zeigt eine perspektivische Ansicht der vorigen Darstellung
• 10 zeigt eine Anordnung mit einem Bürstenhalter als Blechbiegeteil
• 11 zeigt eine perspektivische Ansicht der vorhergehenden Figur

The invention is described below by way of example, without limiting the general inventive concept, using exemplary embodiments with reference to the drawings.

• 1 shows a slip ring brush mounted in a brush holder
• 2 shows a slip ring brush in section
• 3 shows a slip ring brush with ribbing
• 4 shows a slip ring brush with smooth shaft
• 5 shows another slip ring brush
• 6 shows a slip ring arrangement
• 7 shows a perspective view of the slip ring arrangement
• 8 shows a slip ring arrangement with two slip ring brushes arranged at an angle to each other
• 9 shows a perspective view of the previous illustration
• 10 shows an arrangement with a brush holder as a bent sheet metal part
• 11 shows a perspective view of the previous figure

In 1 A slip ring brush according to the invention is shown mounted in a brush holder. The brush holder 20 has a bore 21 for receiving the brush. Within the bore is the press-in mandrel 30 with a mandrel head 32 and a bore 31 for receiving at least one brush wire, preferably a plurality of brush wires 39. For assembly, the press-in mandrel 30 is pulled in direction 38 against or into the brush holder, so that the bore 21 of the brush holder 20 is widened by the mandrel head 32 and a positive connection with the brush holder is established. The brush wires 39 are secured in the bore 31, preferably by crimping. In special cases, a soldered connection of the brush wires to the bore would also be possible. However, this has the previously described disadvantages of a mechanically stressed solder joint. Alternatively, the press-in mandrel could have a longitudinal slot in the area of the bore 31 to enable a spring effect. The brush wires 39 could thus be clamped in a force-fitting manner.

The 2 shows a slip ring brush before assembly. The press-in mandrel is shown as an example with a predetermined breaking point 36 and a detachable part 37. Due to the tensile load on the press-in mandrel during assembly, the press-in mandrel tears at the predetermined breaking point, so that only a shortened end of the mandrel protrudes from the bore, as shown in the 1 is shown.

In 3 A slip ring brush is shown in perspective view. To improve the positive engagement with the bore, the slip ring brush preferably has grooves or a knurl 33 adjacent to the mandrel head 32.

The 4 shows another slip ring brush with a smooth shaft.

In 5 is another embodiment of a slip ring brush with a specially shaped mandrel head 32, which has a structure that can be pressed into the bore of the brush holder. Here, the knurl 33 does not produce the 3 , but rather the mandrel head 33 provides the positive locking. For this purpose, the mandrel head preferably has first rotationally symmetrical structures that provide fixation in the longitudinal direction of the mandrel and second non-rotationally symmetrical structures that prevent rotation of the mandrel.

In 6 A slip ring arrangement is shown. A brush holder 20 is mounted on a preferably insulating carrier plate 50 to form a brush block. The brush holder 20 carries a first slip ring brush 41, which slides on a sliding track 60 that is rotatable relative to the slip ring brush. A cable lug 53 is provided for contacting the brush holder 20. Of course, contacting can also be achieved in other ways, such as by soldering to a circuit board or other cable connection types, for example via plugs. The brush holder 20 is advantageously designed as a milled part or as a cast part. The slip ring brushes are attached to the brush holder by means of a press-in connection, as described above.

In 7 A perspective view of a slip ring arrangement corresponding to the previous figure is shown. Here, four slip ring brushes 41 are connected to a brush holder 20. The four brushes of each brush holder run on a common sliding track and are thus electrically connected in parallel. This reduces the contact resistance and contact noise. The current carrying capacity is increased. Of course, any number of slip ring brushes can also be attached to the brush holder, provided the brush holder is sized accordingly.

8 shows a slip ring arrangement with a first slip ring brush 41 and a second slip ring brush 42, which is arranged at an angle thereto, preferably at an angle of 90°. Both slip ring brushes are held by the same brush holder 20 and are thus also electrically connected in parallel.

9 shows a perspective view of the arrangement from the previous figure.

10 shows an arrangement in which the brush holder 20 is designed as a bent sheet metal part. This allows for particularly simple and cost-effective production. The brush holder is also attached to the carrier plate by means of press-in connections 51, 52. Of course, other connections, such as screws or similar, can also be used.

11 shows the arrangement of the previous figure in perspective view. Here, two first slip-ring brushes 41 and two second slip-ring brushes 42 are attached to a brush holder 20. Of course, any other number of slip-ring brushes can also be attached to the brush holder, provided the brush holder is sized accordingly.

List of reference symbols

20

brush holder

21

Hole (of 20)

22

Connection tab

30

Press-in mandrel

31

Hole for brush wires (of 30)

32

Thornhead

33

knurl

36

Predetermined breaking point

37

detachable part of the mandrel

38

Direction of movement

39

Brush wires

41

first slip ring brush

42

second slip ring brush

50

carrier plate

51, 52

Press-in connections

53

cable lug

60

Slideway

Claims (11)

Slip ring brush (41, 42) comprising at least one brush wire (39), characterized in that the slip ring brush (41, 42) comprises a press-in mandrel (30) which comprises a mandrel head (32) and/or a structure for pressing into a bore (21) of a brush holder (20) and a bore (31) for receiving the at least one brush wire (39). Slip ring brush (41, 42) according to one of the preceding claims, characterized in that the press-in mandrel (30) has a part (37) which can be separated via a predetermined breaking point (36). Slip ring brush (41, 42) according to one of the preceding claims, characterized in that the at least one brush wire (39) is held in a bore (31) of the press-in mandrel (30). Slip ring brush (41, 42) according to Claim 3 , characterized in that the at least one brush wire (39) is held in a bore (31) of the press-in mandrel (30) by a crimp connection. Brush holder (20) with at least one bore (21) for receiving at least one slip ring brush (41, 42) according to one of the preceding claims. Brush holder (20) after Claim 5 , characterized in that at least two slip ring brushes (41, 42) are arranged at an angle to one another. Brush holder (20) after Claim 6 , characterized in that at least two slip ring brushes (41, 42) are arranged at an angle of 90° to one another. Brush block comprising at least one brush holder (20) according to Claim 5 . Slip ring arrangement comprising at least one brush holder (20) according to Claim 5 . Slip ring arrangement comprising at least one brush block according to Claim 8 . Method for assembling a slip ring brush (41, 42) according to one of the Claims 1 until 4 , characterized in that the press-in mandrel (30) is pulled through the bore (21) of a brush holder (20) so that a press fit is created between the press-in mandrel (30) and the bore (21).

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