DE20022707U1 - Power supply means - Google Patents

Description

Wilkhahn * w£ft"P01/OO/EP February 21, 2000

POWER SUPPLY EQUIPMENT

The invention relates to a power supply device with a metal profile which forms a channel in the interior and an undercut groove in the outer wall for tightening fastening elements.

Such metal profiles are used as structural elements in shelving systems, for example as vertical columns to which the floor supports for the individual shelves are attached. To save weight and material, the metal profiles are usually designed as hollow profiles, so that they have at least one channel inside that runs lengthways. The fastening elements, such as the floor supports, are clamped into the undercut groove of the metal profile using slot nuts. Holes are usually formed at certain longitudinal intervals at the base of the groove, making it easier to attach the fastening elements to the metal profile in defined positions.

It is already known to design metal profiles used in shelving as busbars to which electrical consumers, such as lights, can be connected in any longitudinal position using suitable adapters. The electrical conductors of the busbars are then insulated from the metal profile by insulation profiles and arranged in such a way that they can be brought into contact with the corresponding contacts of the adapter. The technical requirements for such a busbar, in particular the requirement to maintain sufficient insulation distances between the individual electrical conductors, lead to certain restrictions with regard to the design of the metal profile. Typically, in conventional busbars, the metal profile must have a relatively wide open groove in which the functional parts of the adapter required for making the electrical contacts and for mechanical fastening can be accommodated. Such a relatively wide open groove impairs the appearance of the metal profile. In the case of high-quality shelving furniture, the technical requirements resulting from the function as a busbar cannot therefore be easily reconciled with the requirements for an aesthetically pleasing design of the metal profile.

The object of the invention is to provide a power supply device for low-

Wilkhahn WKN POI/OO/EP February 21, 2000

to integrate electrical consumers operated at low voltage into the metal profile in such a way that a high degree of constructive freedom is retained with regard to the design of the metal profile and yet a reliable electrical contact can be guaranteed.

This object is achieved in a power supply device of the type mentioned at the outset in that the channel accommodates a self-supporting electrical conductor which is only held at certain points along its length by insulating spacers, and in that an adapter can be clamped into the groove which is in electrical contact with the conductor on the one hand by means of a contact pin which is insulated from the metal profile and projects through an opening into the channel, and on the other hand is in direct electrical contact with the metal profile.

According to the invention, the conductor accommodated in the channel and the metal profile itself create a two-phase busbar that is suitable for connecting electrical consumers that operate at low voltages that are not dangerous for humans, such as low-voltage halogen lamps and the like. The undercut groove, which is also used here to attach the adapter, does not need to be larger than in conventional metal profiles for shelf elements that have a purely mechanical function. By accommodating the electrical conductor in the channel of the metal profile that is already there, a compact design of the profile is possible. The self-supporting arrangement of the conductor in the channel has the advantage that an insulation profile or insulating sheath is not necessary and that the conductor can be contacted at practically any point without the contact reliability being impaired by the insulation. In this way, a reliable electrical contact can be made even if the conductor is only accessible through a very small opening, for example through one of the holes that are already there for the floor supports.

The self-supporting electrical conductor must naturally have a certain degree of bending stiffness and accordingly a relatively large cross-section to prevent contact with the metal profile. This large cross-section of the conductor also benefits the electrical conductivity, so that line losses are minimized and no noticeable voltage drop occurs even with longer cable lengths and/or a large number of consumers.

Wilkhahn WKN PO] / OO/ EP 21.2.2000

Finally, by dispensing with continuous insulation, the dissipation of heat loss from the electrical conductor is also improved.

Advantageous embodiments of the invention emerge from the subclaims.

The electrical conductor is preferably formed by a solid copper wire. The channel of the metal profile which accommodates the copper wire is preferably closed all around and is only accessible through separate openings arranged at certain longitudinal distances. In this way, mechanical weakening of the metal profile by a continuous slot in the wall of the channel is avoided. The grid of the openings can, however, be chosen so finely that the limitation of the possible connection points does not have a disadvantageous effect in practice.

The contact pin of the adapter is preferably elastically pre-tensioned against the electrical conductor so that a reliable electrical contact is guaranteed. The elastic reaction forces acting on the adapter can be introduced directly into the metal profile by a sliding block engaging in the undercut groove.

If the metal profile is, for example, an anodized extrusion profile made of aluminum, special measures must be taken to establish direct electrical contact between the adapter and the metal profile due to the insulating effect of the anodized layer. In a particularly preferred embodiment, the openings that allow access to the conductor inside the channel are formed by countersunk holes. In the area of the conical depression, the anodized layer is removed so that a secure electrical contact can be established between the adapter and the metal profile at this point. The adapter then preferably has a metal sleeve that surrounds the contact pin and is electrically insulated from it, which is conically tapered at one end and is elastically prestressed against the cone of the countersunk hole. The reaction forces resulting from this prestress can be introduced into the metal profile again via the sliding block. This sleeve is preferably held in the sliding block with a certain axial play and accommodates an insulating sleeve inside, in which the contact pin is held with a certain axial play. In this way

Wilkhahn WknPOI ZOO/EP February 21, 2000

The contact pin, the insulation sleeve, the metal sleeve and the sliding block are captively connected to form a unit.

The slot nut preferably has a tubular shaft surrounding the metal sleeve, to which the electrical consumer connected with the aid of the adapter is held. A round nut screwed onto an external thread of this shaft rests on the outer surface of the metal profile and thus enables the slot nut to be firmly clamped in the undercut groove of the metal profile.
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An adapter of the type described above can also be used as a feeder for feeding the current into the electrical conductor. In a particularly preferred embodiment, however, the feeder is integrated into a special node element which is specially designed for stable fastening to one end of the metal profile and serves to connect further construction clamps which, together with the metal profile, form a stable spatial grid.

In the following, an embodiment of the invention is explained in more detail with reference to the drawing.

Show it:

Fig. 1 shows a cross-section of a metal profile with an adapter attached to it for supplying power to a lamp;

Fig. 2 enlarged partial sections of the metal profile and the adapter according to Figure 1;

Fig. 3 is a front view of the adapter;

Fig. 4 a section through the metal profile in connection with a node element with integrated feeder;

Fig. 5 a longitudinal section through the metal profile with node element and

feeder; and

Wilkhahn * · WKWPOl/OO/EP February 21, 2000

Fig. 6 is a schematic diagram of a furniture part with power supply device.

Figure 1 shows a cross-section of a metal profile 10 known per se, for example made of anodized aluminum, which can form a vertical column of a shelf, for example. This metal profile 10 has a square outer cross-section with slightly convexly curved sides and is stiffened on the inside by a crossbar 12 in which a central channel 14 with a circular cross-section is formed. In the example shown, the outer wall of the metal profile 10 is interrupted at one corner by a slot 16 (Figure 2), which together with one of the four hollow chambers delimited by the crossbar 12 forms an undercut groove 18. Floor supports and other fastening elements (not shown) can be fixed in the groove 18 in a known manner using sliding blocks. In the example shown, however, an adapter 20 is inserted into the groove 18, which serves for mechanical fastening and at the same time for supplying power to a lamp 22. The lamp 22, for example a low-voltage halogen lamp, is connected to the adapter 20 by a two-axis joint 24.

To supply power to the lamp 22, an electrical conductor 26 is arranged in the channel 14 of the metal profile 10, from which the current is tapped by a contact pin 28 of the adapter 20. The current is returned directly via the metal profile 10, which is in electrical contact with a metal sleeve 30 of the adapter 20. The conductor 26 is a solid, stiff copper wire that is arranged in a self-supporting manner in the channel 14 and forms an insulating annular gap with the walls of this channel.

The structure of the adapter 20 is explained in more detail below with reference to Figures 2 and 3. In Figure 2, the adapter 20 is shown separately from the metal profile 10 for reasons of clarity.

The supporting element of the adapter 20 is a sliding block 32 made of metal, which engages with an elongated plate 34 designed as a toggle in the undercut groove 18 and has a tubular shaft 36 extending from the plate 34, which protrudes through the slot 16 of the metal profile 10 and is screwed at the free end to an internally threaded socket 38 of the joint 24. When the sliding block 32 is rotated by 90° around its

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21.2.2000

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Longitudinal axis is rotated, the plate 34 is oriented in the longitudinal direction of the slot 16 so that it can be inserted through the slot 16 into the undercut groove 18. The plate 34 can then be locked in the undercut groove 18 by rotating it by approximately 45°. A round nut 40 is screwed onto the external thread of the shaft 36, with which a fitting piece 42 surrounding the shaft 36 can be clamped against the outer surface of the metal profile 10 so that the plate 34 is pulled firmly against the undercuts of the groove 18. In this way, a stable mechanical connection is produced between the metal profile 10 and the joint 24 of the lamp 22.

15 20

30 35

The metal sleeve 30 is guided axially displaceably in the shaft 36 of the sliding block 32 and has a thickened head 44 on the inside of the plate 34 that tapers conically towards the free end. The opposite end of the metal sleeve 30 is supported by an electrically conductive coil spring 46 on an electrically conductive part of the joint 24. The head 44 is held on the plate 34 by two screws 48 that limit the axial play of the metal sleeve 30 in relation to the sliding block 32 and connect the metal sleeve and the sliding block to form a unit.

The contact pin 28 is guided with limited axial play in an insulating sleeve 50, which in turn is held captive in the metal sleeve 30. A coil spring 51 rests on an inner shoulder of the insulating sleeve 50 and has a tendency to press the contact pin 28 out of the head 44 of the metal sleeve 30. In the state shown in Figure 2, the contact pin is held by a collar on a shoulder of the insulating tube 50. The contact pin is connected to the lamp 22 via a flexible cable 52, while the metal sleeve 30 is electrically connected to the lamp via the conductive coil spring 46.

The conductor 26 running in the closed channel 14 of the metal profile 10 is accessible through a bore 54 formed in the base of the undercut groove 18, which has a countersunk cone 56 at the outer end. In the area of this countersunk cone, the insulating anodized layer of the metal profile 10 is removed.

If the adapter 20 is mounted in the manner shown in Figure 1 with the aid of the sliding block 32 and the round nut 40 at the appropriate height in the undercut groove 18

Wilkhahn WKN POl / 00/ EP 21.2.2000

of the metal profile 10, the free ends of the contact pin 28 and the insulating sleeve 50 protrude through the bore 54 and the tip of the contact pin 28 abuts the conductor 26 so that the contact pin is pressed back slightly into the insulating tube against the force of the coil spring 51. In this way, the contact pin is held under tension in contact with the conductor 26 so that a reliable electrical contact is ensured. The engagement of the insulating tube 50 in the bore 54 prevents a short circuit caused by the contact pin touching the metal profile 10. The conically tapered head 44 of the metal sleeve 30 engages in the countersunk cone 56 and is also pressed back slightly against the force of the coil spring 46 so that sufficient contact pressure between the metal sleeve 30 and the metal profile 10 is ensured in the area of the countersunk cone 56. In this way, a simple and reliable electrical connection of the lamp 22 to the power supply is achieved with the very small adapter 20.

Figures 4 and 5 show the metal profile 10 in connection with a node element 58, in which a feeder 60 for the current supply to the conductor 26 is integrated.

The node element 58 is a metal casting that is securely attached to one end of the metal profile 10 and forms two legs 62 arranged at right angles to one another, which allow the stable connection of longitudinal and transverse supports (not shown) of a shelf. After the final assembly of the shelf, the node element 58 lies invisibly under the lowest shelf.

A connection block 64 oriented in the direction of the bisector between the legs 62 is adapted to the outer contour of the metal profile 10 and is clamped in the undercut groove 18 of the metal profile by means of a sliding block 66.

The feeder 60 is, as far as the contacting of the conductor 26 is concerned, constructed analogously to the adapter 20 according to Figure 2 and has an insulation tube 68 in which a contact pin 70 is guided. The slightly tapered end of the insulation tube 68 again engages in a hole at the bottom of the undercut groove 18, and the contact pin 70 is tensioned against the conductor 26 by a helical spring 72. The other end of the helical spring 72 rests on a

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in the insulation tube 68, which is connected via a cable 76 to one of the two secondary outputs of a transformer (not shown). The terminal 74 is held in the insulation tube 68, for example, with the aid of a fixing screw. The conductive and mechanically flexible connection to the contact pin 70 is made in this case via the coil spring 72.

The insulation tube 68 and the cable 76 are placed in a suitably contoured groove 78 formed in the top of the node element 58. Two transverse bores 80 allow the insulation tube 68 to be fixed in the node element 58 by means of clamping screws.

As can be seen from Figure 5, the sliding block 66 is arranged below the feeder 60 on the connection block 64 and can be tightened with the aid of a tension bolt 82. The free end of the tension bolt 82 engages in one of the holes 54 in the metal profile 10, so that it is ensured that the node element 58 is fixed to the metal profile 10 at a defined height. Since the node element 58 is located at the (lower) end of the metal profile 10, the sliding block 66 does not need to be designed like a toggle, but can be pushed into the undercut groove 18 from the free end before the tension bolt 82 is screwed in further.

If several electrical consumers are connected using the adapters 20 shown in Figures 1 to 3, the current intensity at the feeder 60 is a multiple of the current intensity that is tapped at the individual adapters 20. It is therefore important that the feeder has particularly good electrical contact with the conductor 26 and, above all, with the metal profile 10. For this reason, the metal profile 10 is contacted using a special clamping screw 84, the tip of which can be pressed firmly into the material of the metal profile 10 at the base of the groove 18. The clamping screw 84 is threadedly engaged with a terminal 86 held on the connection block 64, to which a second cable 88 leading to the transformer is connected.

Since in this embodiment the tension bolt 82 engages in one of the bores 54, the contact pin 70 does not fit into the grid of the bores 54. For this reason, a special bore is formed in the bottom of the groove 18 for the contact pin and the insulation tube.

Wilkhahn WKnVoi/OO/EP February 21, 2000

A lower end section of the central channel 14 of the metal profile 10 is provided with an internal thread. An insulating plug 90 is screwed into this end section, which holds one end of the conductor 26. The insulating plug 90 is located at least at the level of the tension bolt 82, so that this tension bolt cannot come into contact with the conductor 26.

The upper end of the conductor 26 is held in an analogous manner by a plug 92.

If the metal profile 10 and the conductor 26 have a relatively large length, it is expedient to slide insulating spacers 94 onto the conductor 26 at certain points, which prevent the conductor 26 from bending and from coming into contact with the inner wall of the channel 14.

Figure 6 shows a schematic horizontal section through a furniture part with four vertical columns, which are formed by metal profiles identical to the metal profile 10, which are designated here with the reference numerals 10, 10a, 10b and 10c to distinguish them. Between these columns there is a schematically indicated shelf 96, under which a light 98 is arranged in the middle.

The power supply device is formed here by the diagonally opposite metal profiles 10 and 10a, both of which accommodate an inner conductor 26. The current from the inner conductor 26 of the metal profile 10 is tapped in the manner described above with the aid of the contact pin 28 of the adapter 20. The second contact of the lamp 98 is not connected to the adapter 20, however, but to a slightly modified adapter 20a, which is attached to the metal profile 10a. This adapter 20a differs from the adapter 20 in that the contact pin 28 and the coil spring 51 are omitted. The cable 100 coming from the lamp 98 is connected here to a threaded bushing 102, which is screwed into the round nut 40 and forms the abutment for the coil spring 46 and at the same time creates a conductive connection between the cable 100 and the metal sleeve 30. In this way, the lamp 98 is electrically connected to the metal profile 10a, so that the current from the inner conductor 26 of the metal profile 10 flows through the lamp 98 into the diagonally opposite metal profile 10a. The metal sleeve 30 of the adapter 20 is not used here to establish an electrical contact with

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Wilkhahn **** *" WßtpOl/00/EP February 21, 2000

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Contact with the metal profile 10 is not required, but serves only in conjunction with the sliding block 32 for the mechanical fastening of the adapter.

In the metal profile 10a, the electrical conductor 26 is not required to supply power to the light 98. This conductor is used here only to supply power to lights that are attached directly to the metal profile 10a in the manner shown in Figure 1. This means that on one and the same piece of furniture, consumers whose power is supplied via two columns, as in the case of the light 98, can be combined with consumers whose power is supplied via only a single column. In this case, the variant shown in Figure 6 has the advantage over a power supply from only a single column that a more even current load is achieved in the various circuits.

Since the metal profiles 10 and 10a are part of a common frame of the furniture part, it cannot generally be assumed that there is a potential separation between these two metal profiles. If the inner conductors 26 of both profiles are used for the power supply, it must therefore be ensured that the voltages supplied to the two conductors 26 on the one hand and the metal profiles 10 and 10a on the other hand are in phase. If the power supply is via two separate electronic transformers, the phase equality can be ensured by electronic synchronization of these transformers.

Claims (12)

1. Power supply device with a metal profile ( 10 ) which forms a channel ( 14 ) in the interior and an undercut groove ( 18 ) in the outer wall for tightening fastening elements, characterized in that the channel ( 14 ) receives a self-supporting electrical conductor ( 26 ) which is only held at certain points along its length by insulating spacers ( 90 , 92 , 94 ), and that an adapter ( 20 ) can be tightened in the groove ( 18 ), which adapter is in electrical contact with the conductor ( 26 ) on the one hand by means of a contact pin ( 28 ) which is insulated from the metal profile ( 10 ) and projects through an opening ( 54 ) into the channel ( 14 ), and on the other hand is in direct electrical contact with the metal profile ( 10 ). 2. Power supply device according to claim 1, characterized in that the channel ( 14 ) is surrounded by a closed wall which has only individual openings ( 54 ) arranged at certain longitudinal intervals. 3. Power supply device according to claim 2, characterized in that the opening ( 54 ) has a bevel or a countersunk cone ( 56 ) on the outer edge and that the adapter ( 20 ) has a metal sleeve ( 30 ) surrounding the contact pin ( 28 ) and electrically insulated therefrom, which contacts the bevel or the countersunk cone ( 56 ) with a head ( 44 ) tapered towards the free end. 4. Power supply device according to claim 3, characterized in that the metal sleeve ( 30 ) is elastically prestressed against the chamfer or the countersunk cone ( 56 ). 5. Power supply device according to one of the preceding claims, characterized in that the contact pin ( 28 ) is surrounded by an insulating sleeve ( 50 ) which projects into the opening ( 54 ). 6. Power supply device according to claim 5, characterized in that the insulating sleeve ( 50 ) forms an abutment for a spring ( 51 ) which biases the contact pin ( 28 ) against the conductor ( 26 ). 7. Power supply device according to one of the preceding claims, characterized in that the adapter ( 20 ) has a sliding block ( 32 ) engaging in the undercut groove ( 18 ), from which a shaft ( 36 ) emerges from the groove, and that the contact pin ( 28 ) is arranged coaxially to the shaft ( 36 ). 8. Power supply device according to claims 4 and 7, characterized in that the sliding block ( 32 ) and the metal sleeve ( 30 ) are connected to form a unit with a certain axial play. 9. Power supply device according to claim 7 or 8, characterized in that an electrical consumer ( 22 ) is attached to the shaft ( 36 ) of the sliding block ( 32 ). 10. Power supply device according to one of the preceding claims, characterized in that a feeder ( 60 ) with a contact pin ( 70 ) for supplying power to the conductor ( 26 ) is integrated into a node element ( 58 ) to be fastened to the metal profile ( 10 ). 11. Furniture frame with two metal profiles ( 10a , 10a ), characterized in that each of the two metal profiles ( 10 , 10a ) is part of a power supply device according to one of claims 1 to 10 and that in-phase voltages are supplied to these power supply devices. 12. Furniture frame with two metal profiles ( 10 , 10a ), each of which forms a channel ( 14 ) in the interior and an undercut groove ( 18 ) in the outer wall for tightening fastening elements, characterized in that the channel ( 14 ) of at least one metal profile ( 10 ) accommodates a self-supporting electrical conductor ( 26 ) which is only held at certain points along its length by insulating spacers ( 90 , 92 , 94 ), and that an adapter ( 20 ) can be tightened in the groove ( 18 ) of this metal profile, which is in electrical contact with the conductor ( 26 ) by means of a contact pin (28) which is insulated from this metal profile ( 10 ) and projects through an opening ( 54 ) into the channel ( 14 ), and that an adapter ( 20 ) is clamped in the groove ( 18 ) of the other metal profile ( 10a ). 20 a) which is in direct electrical contact with this metal profile ( 10 a).