WO2008048086A1

WO2008048086A1 - Electric connector rail and power plug connectable to such a rail

Info

Publication number: WO2008048086A1
Application number: PCT/NL2006/000521
Authority: WO
Inventors: Jan Cornelis Enkelaar; Hendrikus Gerardus Nicolaas Marie Kik; Mathis Heller; Willem Verburg; Mathijs Van Dijk
Original assignee: Eos Systems B.V.
Priority date: 2006-10-16
Filing date: 2006-10-16
Publication date: 2008-04-24
Also published as: WO2008046836A1

Abstract

An electrical connector rail has an insulator body (9; 409) and a carrier (6; 406) fixed to each other and both extending in the same longitudinal direction. One or more conductors (13-15; 413-415) are embedded in the insulator body (9; 409) and extending in the longitudinal direction of the carrier (6; 406) in a position accessible by perforating the insulator body (9; 409). Also described is a power plug (5; 405) connectable to such a rail which has one or more contact pins (16-18; 416-418) projecting from a housing (19; 419) of the plug and having a sharp distal end (26-28; 426, 428) for perforating the insulator body (9; 409) for providing access of the contact pins (16-18; 416-418) to the conductor or conductors (13-15; 413-415) embedded in the insulator body (9; 409).

Description

TITLE: Electric connector rail and power plug connectable to such a rail

FIELD AND BACKGROUND OF THE INVENTION

The invention relates to an electric connector rail and to a power plug for use in combination with such a rail. Conductors of electric distribution systems in buildings are usually arranged in channels that extend in or along floors, walls and ceilings. Compared with tubing that is installed in the walls, floors and ceilings, surface mounted raceways offer the advantage of more flexibility with respect to installation and rearrangement after a building has been completed. Examples of such systems are disclosed in U.S. patent 6,717,049 and in U.S. patent application 2004/08384. In such systems, the installation of sockets to which power plugs can be connected is cumbersome. In German patent application 198 35 098, it has been proposed to facilitate the installation of sockets by prearranging conductor tracks in two sets of three in the channel so as to be engageable by clamping. However, the conductor tracks are not protected.

SUMMARY OF THE INVENTION

It is an object of the present invention to allow the distribution of electricity in a building with a great flexibility regarding the positions where appliances can be connected to the distribution system and in which the users are effectively safeguarded from contacting the conductors.

According to one aspect of the invention, this object is achieved by providing a rail according to claim 1. The invention may also be embodied in a power plug according to claim 13, which is specifically suitable for use in combination with a rails according to claim 1.

Because the conductors are shielded by the insulator body, the users are safely guarded from directly or indirectly coming in electrically conductive contact with the conductor and inadvertent short-circuiting is reliably prevented. Nevertheless, because the contact pin can be brought in contact with the conductor by perforating the insulator body in any position where the insulator body is accessible thereby, a large degree of freedom is obtained with respect to the locations along the rail where power plugs can be connected to the rail.

Particular elaborations and embodiments of the invention are set forth in the dependent claims.

Further features, effects and details of the invention appear from the detailed description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a cross-sectional view of an example of a rail according to the invention with an example of a power plug according to the invention connected thereto;

Fig. 2 is a perspective view of a second example of a rail according to the invention with a second example and a third example of a power plug according to the invention connected thereto; Fig. 3 is a perspective view of a rail as shown in Fig. 2 with a fourth example of a power plug according to the invention connected thereto;

Fig. 4 is a perspective view of a fifth example of a power plug according to the invention;

Fig. 5 is a perspective view of a third example of a rail according to the invention and of the power plug according to Fig.4 shown in a position and condition suitable for connection to the rail;

Fig. 6 is a perspective view of the rail and the connecting portion shown in Fig. 5, but with the power plug connected to the rail;

Fig. 7 is a perspective view of the power plug shown in Figs. 4-6, but in a condition for being connected to the rail; Fig. 8 is a perspective view of a connector for connection to a power plug according to Figs. 4 and 5; and

Fig. 9 is a perspective view of the power plug and the rail in the configuration as shown in Fig. 6 and of the connector shown in Fig. 8 in a position ready for connection to the power plug.

DETAILED DESCRIPTION

The invention is first described with reference to the example shown in Fig. 1 in which an electrical connector rail 1 is shown in mounted condition against a bottom end of a wall 2, where the wall 2 meets a floor 3 covered by a carpet 4, a power plug 5 being connected to the rail 1.

The rail 1 has an elongate carrier in the form of a housing 6 having a front face 7 and an opening 8 in the front face 7. A flexible lip 64 projects from a lower end of the housing 6 for accommodating to unevenness of the floor 3 and/or the floor cover 4 and allows to bring cords and the like, such as an antenna cable, into a space under the housing 6 by slipping the cable transversally through a nip or slit between the lip 64 and the floor cover 4. According to the present example, the housing 6 is a profile that has a cross-section that is constant over its entire length. An insulator body 9 extends in the housing 6 in longitudinal direction of the housing 6 in a fixed position accessible via the opening 8 in the front face 7. According to the present example, the insulator body 9 is transversally fixed, because it is in contact with opposite walls of a chamber 10 in the housing 6. More specifically, the insulator body 9 is immobilized particularly effectively in transversal direction, because it fully fills up a portion of the chamber 10 remote from the opening 8. Anchoring ribs 11 projecting into grooves 12 (not all indicated by reference numerals) in the chamber 10 keep the insulator body from moving towards the opening 8. Because the carrier is in the form of a housing, the fixation of the insulator body is achieved relatively easily and the insulator body 9 is shielded in as far as it does not need to be accessible.

Three conductors 13-15 are circumferentially surrounded by and in contact with material of the insulator body 9 and each extend in the housing 6 in an orientation parallel to the longitudinal direction of the housing 6 and to each other in a position accessible by perforating the insulator body 9 via the opening 8. In the present example, the upper conductor 13 provides a single phase, the lower conductor 15 provides connection to the neutral and the central conductor 14 is connected to earth ground. For electric connection to the conductors 13-15 embedded in the insulator body 9, contact pins 16, 17, 18 of the power plug 5 have accessed the conductors 13-15 via the opening 8 by piercing the contact pins 16-18 into the insulator bodj^ 9 so that the insulator body 9 has been perforated. A proximal end portion of each of the contact pins 16-18 is fixedly located in an insulating power plug housing 19. The contact pins 16-18 each have a distal end portion projecting from the housing 19 up to the conductor 16-18 with which the contact pin 16-18 is in electric contact. Via a connection 20-22, a proximal end portion of the respective contact pin 16-18 is connected to a conductor wire 23- 25. From the connections 20-22, the connector wires 23-25 continue in a power cord 40. For perforating the insulator body 9 to provide access of the contact pin to a conductor embedded in the insulator body, the contact pins 16-18 each have a sharp distal end 26-28 for perforating the instilator body 9. In the present example, the sharp distal ends 26-28 are in the form of sharp points, which require relatively little force to pierce the insulator body 9. Because the conductors 13-15 are shielded by the insulator body 9, living beings in the vicinity of the rail 1 are safely guarded from directly or indirectly coming in electrically conductive contact with the conductors 13-15. Nevertheless, because the contact pins 16-18 can be brought in contact with the conductors 16-18 by perforating the insulator body 9 in any position corresponding to a position where the power plug 5 can be inserted into the opening 8, a large degree of freedom is obtained with respect to the locations along the rail 1 where power plugs 5 can be connected to the rail 1. Also, because the rail 1 will generally have a substantial length, a large number of power plugs 5 can generally be connected to the rail 1. To give the rail 1 a bending stiffness that allows the rail 1 to be mounted with relatively few mounting positions, the housing 6 is of a harder and more rigid material than the insulator body 9. In the present example, the housing 6 is an extruded metal (preferably aluminum alloy) profile and mounted to the wall 2 by means of mounting clamps 29 that are fixed to the wall 2 by means of screws 30, 31 and that have snap fingers engaging snap-in edges 32, 33 on a back face of the housing 6.

The housing 6 includes retaining members 34, 35 for retaining the power plug 5 in contact with the conductors 16-18. The retaining membei's 34, 35 are engaged by anchoring members 36, 37 of the power plug 5 for engaging a retaining member of an electrical conductor rail. In the present example, the anchoring members 36, 37 are provided in the form of snap fixation members, which allows the anchoring condition to be established in a simple manner by pressing the power plug 5 towards the insulating member 9 with sufficient force to allow the snap fixation members 36, 37 to engage the retaining members 34, 35. By retaining the contact pins 16-18 pressed against the conductors 13-15, reliable electric contact between the contact pins 16-18 and the conductors 13-15 is ensured.

In the present example, the retaining members 34, 35 extend continuously in longitudinal direction of the housing 6. This allows the anchoring members 36, 37 to engage the retaining members 34, 35 in any position in a continuous range along the rail 1.

The anchoring members 36, 37 each have a projection 38, 39 and the projections 38, 39 face in opposite directions, so that the continuous retaining flanges 34, 35 can be engaged thereby. To release the power plug 5 from the retaining flanges 34, 35, it is sufficient to press the flexible fingers 36, 37 that form the snap fixation members together, so that the projections 38, 39 thereof disengage from the retaining flanges 34, 35. The power plug 5 can then be disconnected from the rail 1.

For ensuring electric contact between the conductors 13-15 and the contact pins 16-18 over a relatively large surface area, it is moreover advantageous if the conductors 13-15 each comprise a plurality of braided filaments. The conductors 13-15 can then easily deform locally when engaged by the contact pins 16-18 into a shape accommodated to the shape of the contact pin surface in contact with that conductor 13-15. Moreover, the contact pins 16-18 can then also be pierced into the conductors 13-15 without substantially damaging the conductors 13-15.

The insulator body 9 is preferably made of elastomeric material, which may be constituted by natural and/or synthetic rubber, e.g. EPPM. Such materials provides electric insulation and tightly encloses contact pins pierced therein so that the contact pins 16-18 and the conductors 13-15 are effectively shielded from moisture. Preferably, the material is elastic enough to close-up when the contact pins 16-18 are drawn out of the insulator body 9, so that the full enclosure of the conductors is re-established when the contact pins 16-18 are drawn out of the insulator body 9. To provide reliable insulation of the conductors 13-15, and in particular to provide reliable insulation in the area of a perforation in the insulator body 9 made by a contact pin after the contact has been pulled out of the perforation the minimum distance over which the conductors 13-15 are spaced from a surface of the insulator body 9 facing the opening 8 is preferably at least 1 mm and more preferably at least 3 mm, in particular if the conductors are to be used for the distribution of higher voltages.

For easy perforation and reliable self-closing of perforations made, it is moreover advantageous if the insulator bodjr 9 is of a material having a hardness lower than 60 Shore A and more preferably lower than 50 Shore A. To reduce the risk of accidental damage to the insulator body, the material of the insulator body preferably has a hardness of more than 40 Shore A. A particularly advantageous combination of resistance against damage, easy perforation and self-healing properties is achieved if the hardness of the material of the insulator body is higher on the outside of the insulator body than on the inside, which may be achieved by providing that the insulator body is composed of layers of different hardness and/or the hardness has a gradient in a direction from the inside to the outside of the insulator body.

In Figs. 2 and 3 alternative power plugs 105, 205, 305 plugged in a rail 101 according to an alternative embodiment of the invention are shown. The power plug 105 has a back face 141 facing away from the rail 101, forming a socket in which openings 142 for receiving contact pins of a standardized power plug, such as for instance a CEE 7/7 plug, are provided. Behind the openings 142, contacts are arranged for contacting the contact pins of the standard power plug, which contacts are electrically connected to the contact pins of the power plug 105. Different configurations of openings for receiving plugs according to different standards may be provided. The power plugs 205 and 305 are each connected to a power cord 240, 340 on a side of the housing and are not equipped with anchoring members such as for instance the power plug 5 shown in Fig. 1. In the example shown in Fig. 3, the power cord is connected to a standard power plug 343 that is plugged-in in a standard socket 344. Thus, the conductors of the rail 101 can be connected to a pre-existing mains network in a simple manner.

In Figs. 4-9, further examples of a rail 401 and a modular power plug 405 are provided.

As is best seen in Figs 4 and 5, the plug 405 has an anchoring member 436 with projections 438, 439 for anchoring behind retaining flanges 434, 435 of the housing 406 of the rail 401. A portion of the plug 405 between the projections 438, 439 is narrower than the distance between extreme distal ends of the projections 438, 439. This allows the portion of the plug 405 between the projections 438, 439 to be inserted through the opening 408 between retaining flanges 434, 435 when the plug is twisted about an axis 445 in the inserting direction defined by the contact pins 416-418 over preferably 90° relative to the final position of the inserted plug. In Fig. 5, the plug 405 is shown in the twisted orientation allowing the plug to be connected and disconnected and in Fig. 6, the plug 405 is shown in the final connected position and orientation.

More specifically, the plug 405 according to the present example includes an anchoring member 436 of which the width is narrow enough to allow it to be inserted through the opening 408 and has opposite ends 438, 439 in a direction perpendicular to the direction in which the width is measured that project apart further so as to be able to hook behind the retaining flanges 434, 435 when the anchoring member 436 is twisted about the axis 445 perpendicular to the rail 401 from an orientation in which the width of the anchoring member 436 is oriented perpendicular to the rail 401 and the axis 445.

In the present example, the largest transversal size of the anchoring member measured between transitions interconnecting the narrowest section and the projections 438, 439 is moreover such, that the anchoring member 436 can rotate, while in a position closely adjacent to the insulator member 409 in a channel bounded by the housing 406, from the orientation in which it has been inserted into the opening 408 to the final orientation in which the contact pins 416-418 can access the conductors 413-415.

To avoid injury due to inadvertent contact with the contact pins 416-418 when the connector is disconnected from the rail 401, the contact pins 416-418 are retractable to a position in which the contact pins 416-418 do not project from a front surface 446 of the plug 405. In Fig. 4, the contact pins are in the retracted position and in Fig. 7, the contact pins are shown in an extended position for contacting. In connection with the anchoring member 436 rotatable while in a position inserted in the opening 408, another advantage of the retractability of the contact pins 416-418 is, that the flanges 438, 439 can be rotated without cutting through the insulator body 409 or needing to be rotatable relative to the contact pins.

The retractability of the contact pins 416-418 has been realized by providing that an insulating housing 419 in which the contact pins 416-418 are fixed is movable relative to the anchoring member 436 between a first position away from the front surface 446 of the anchoring member 436 and a second position closely adjacent to the front surface 446 of the anchoring member 436. When the housing 419 is in the first position, the contact pins 416-418 are retracted behind the front surface 446 and when the housing 419 is in the second position, the contact pins 416-418 project through openings in the front surface 446 of the anchoring member 436.

As is best seen in Fig. 6, when in the connected condition with the housing 419 in the second position relative to the anchoring member 436, the housing 419 has a portion inserted in the opening 408 between the retainer flanges 434, 435. This portion of the housing 419 has a length larger than the distance between the flanges 434, 435 and a width such that it fits between the flanges 434, 435 with little play. Thus, it is ensured that the housing 419 can only be brought in the second position, in which the contact pins 416-418 are extended to contact the conductors 413-415, if the housing 419 is properly aligned with the rail 410 and effective electric contact between the contact pins 416-418 and the conductors 413-415 is ensured.

The housing 419 is connected to the anchoring member 436 via a lever 447, which is pivotable between a position projecting from the housing 419 (see Figs. 4 and 5) and a position extending along the housing (see Figs. 6, 7 and 9). In use, when a plug 405 is to be connected to a rail 401, the plug 405 is first moved towards the desired position along the rail in a direction 448 perpendicular to the rail 401 and to the front face 407 of the rail 401 with the lever 447 in the position projecting from the housing 419 as is shown in Fig. 5. When the anchoring member 436 is in abutment with the insulator body 409, the plug 405 is twisted in a plane parallel to the front face 407 of the rail and in a sense indicated by an arrow 449 about the imaginary axis 445 until an orientation is reached in which the width of the housing 419 is perpendicixlar to the rail 401. When this orientation is reached, the projections 437, 438 of the anchoring member 436 engage behind the retaining flanges 434, 435 and a portion of the housing closest to the rail 401 is oriented to fit between the retaining flanges 434, 435 on opposite sides of the opening 408. This allows the lever 447 to be moved from the position projecting from the housing 419 to the position extending along the housing 419 (shown in Fig. 6). While the lever is pivoted to the position extending along the housing 419, the contact pins 416- 418 are extended out of the openings in the front surface of the anchoring member 436 and access the conductors via the opening 408 by perforating the insulator body. Since the projections 437, 438 of the anchoring member 436 are hooked behind the retaining flanges 434, 435 and the lever has a length from its pivoting axis 450 that is larger than the distance to its pivoting axis where the lever 447 engages the housing, a power transmission is obtained in which the force exerted on the housing 419 which causes the contact pins 416-418 to be pierced into the insulator body, is larger than the force exerted by the user onto the lever 447. This facilitates perforation of the insulator member 409 to access the conductors 413-415.

As is best seen in Fig. 7, the sharp distal ends of the blade-shaped contact pins 416-418 are in the form of cutting edges facing away from the housing 419. This provides the advantage that the contact pins can be made to contact the conductors 413-416 over a relatively large surface. Moreover, the blade-shaped contact pins 413-416 can be pierced into the insulator member body 409 in a direction with a directional component parallel to the direction in which the blade-shape is oriented.

After the power plug 405 has been brought in the position shown in Fig. 6, a suitable connector can be connected to the power plug, depending on the desired connection to be made. To this end, the power plug 405 has contacts recessed in slits 451-453 (see Fig. 9) in a face facing away from the contact pins 416-418.

A connector 454 is designed for connection to the contact plug 405 such that contacts 455-457 of the connector 454 are in electric contact with respective ones of the contacts 451-453 of the power plug 405. The power plug 405 has an opening 458 and guide ribs 459, 460 that are arranged for slidable engagement with a tongue 461 and, respectively, hook members 462, 463 in a direction transverse to the direction in which the contacts 455-457 of the connector 454 are to be maintained pressed against the contacts in the slits 451-453 of the power plug 405 and transverse to the direction in which the lever 447 is to be moved for disconnecting the power plug 405. Because the connector 454 is connectable to the power plug 405 in a direction transverse to a direction m which its contacts are held in contact with contacts of the power plug, reliable contact between the contacts of the connector 454 and the contacts of the power plug 405 is ensured in a simple manner. Furthermore, because the connector 454 is connectable to the power plug 405 in a direction transverse to the direction in which an operating member 447 of the power plug 405 is to be moved for disconnecting the power plug 405 from the rail 401, the connector 454 also serves as a lock for keeping the operating member 447 of the power plug from inadvertently moving to a position for disconnecting the power plug.

Within the framework of the invention as defined by the claims, many other variants are conceivable. For instance, if the carrier is of an electrically conductive material, it is also possible to use the housing instead of a conductor embedded in the insulator body as the connection to earth ground. Alternatively, the carrier may also be of another material than metal, such as a plastic material such as PVC. The plastic material may be reinforced, for instance with fibres which may be distributed anisotropically or isotropically, for instance for instance obtained by pultrusion. Instead of extending partially around the insulator body as a housing, the carrier may also be in another form, for instance extending behind the insulator body and connected thereto by one or more anchoring flanges extending in the insulator bod}'. Furthermore, the rail may also be adapted for installation in other locations than as a plinth, for instance bjr being adapted to be installed against a wall or a ceiling, by being integrated as a profile of a separation wall

or by forming a door post.

Also other conductor configurations are conceivable, such as a configuration including conductors distributing two phases and the neutral or, for larger installations e.g. in workshops, distributing three phases and the neutral. In low voltage applications, only a single conductor embedded in the insulator body may be sufficient, the housing of electrically conductive material is then connected to the other pole.

Claims

1. An electrical connector rail comprising, an elongate carrier (6; 406); an elongate insulator body (9; 409) fixed to the carrier (6; 406) and extending in longitudinal direction of the carrier (6; 406); and at least one conductor (13-15; 413-415) embedded in the insulator body

(9; 409) in longitudinal direction of the insulator body (9; 409) in a position accessible by perforating the insulator body (9; 409).

2. A rail according to claim 1, wherein the carrier (6; 406) is housing having a front face (7; 407) and an opening (8; 408) in the front face (7; 407), the insulator body (9; 409) is accessible via the opening (8; 408) in the front face (7; 407) of the housing; and the at least one conductor (13-15; 413-415) embedded in the insulator body (9; 409) is accessible by perforating the insulator body (9; 409) via the opening (8; 408) in the front face (7; 407).

3. A rail according to claim 1, wherein the carrier (6; 406) is of a harder and more rigid material than the insulator body (9; 409).

4. A rail according to claim 3, wherein the insulator body (9; 409) is of elastomeric material.

5. A rail according to any one of the preceding claims, wherein the insulator body (9; 409) is of a material having a hardness lower than 60 Shore A.

6. A rail according to any one of the preceding claims, wherein the carrier (6; 406) is of metal.

7. A rail according to any one of the preceding claims, wherein the carrier (6; 406) includes at least one retaining member (35, 35; 434, 435) for retaining a power plug (5; 405) in electric contact with the at least one conductor (13-15; 413-415).

8. A rail according to claim 7, wherein the at least one retaining member (35, 35; 434, 435) extends continuously in longitudinal direction of the carrier (6; 406).

9. A rail according to any one of the preceding claims, wherein the at least one conductor (13-15; 413-415) comprises a plurality of braided filaments.

10. A rail according to claim 2, wherein the insulator body (9; 409) fully occupies at least a portion of a chamber (10) in the housing (6; 406) remote from the opening (8; 408).

11. A rail according to any one of the preceding claims, wherein at least two of the conductors (13-15; 413-415) are embedded in the insulator body (9; 409).

12. A rail according to any one of the preceding claims, wherein the at least one conductor (13-15; 413-415) is spaced at least 1 mm from a surface of the insulator body (9; 409) facing the opening (8; 408).

13. A power plug comprising a housing (19; 419), at least one contact pin (16-18; 416-418) projecting from the housing (19; 419) and at least one connection via which a proximal end portion of the at least one contact pin (16- 18; 416-418) is connected or connectable to a conductor wire (23-25), wherein the contact pin (16-18; 416-418) has a sharp distal end (26-28; 426, 428) for perforating an insulator body (9; 409) for providing access of the contact pin (16-18; 416-418) to a conductor (13-15; 413-415) embedded in the insulator body (9; 409).

14. A plug according to claim 13, wherein the sharp distal end (26-28;

426, 428) includes a sharp point.

15. A plug according to claim 13 or 14, wherein the sharp distal end (426, 428) includes a cutting edge facing away from the housing (419).

16. A plug according to any one of the claims 13-15, further comprising at least one anchoring member (36, 37; 436) for engaging a retaining member (35, 35; 434, 435) of an electrical conductor rail (1; 101; 401).

17. A plug according to claim 16, wherein the at least one anchoring member has at least two anchoring projections (38, 39; 438, 439), said projections (38, 39; 438, 439) facing in opposite directions

18. A plug according to claim 17, of which a portion between the projections (38, 39; 438, 439) is narrower than the distance between extreme distal ends of the projections (38, 39; 438, 439).

19. A plug according to any one of the claims 13-18, wherein the housing (419) has a face facing away from the at least one contact pin (416-418), at least one opening (142; 451-453) for receiving a contact pin (416-418) being provided in said face and a contact surface electrically connected to, or formed on, the at least one contact pin (16-18; 416-418) being located behind at least one of said openings (142; 451-453) for contact with a contact pin of a connector (454), which is inserted in that at least one opening (408).

20. A plug according to any one of the claims 13-19, wherein the contact pin (416-418) is retractable to a position in which the contact pin (416-418) does not project from the plug (405).

21. A plug according to claim 20, further comprising an insulating housing (419) in which the contact pin (416-418) is fixed, said housing (419) being movable relative to an anchoring member (436) between a first position away from a front surface (446) of the plug (405) and a second position closely adjacent to the front surface (446) of the plug (405), wherein, when the housing (419) is in the first position, the contact pin (416-418) is retracted behind the front surface (446) and when the housing (419) is in the second position, the contact pin (416-418) projects through openings in the front surface (446).

22. A kit comprising a power plug (405) according to claim 21 and a connector (454) electrically connectable to the power plug (405) on a side of the power plug (405) facing away from the contact pin (416-418), the power plug (405) comprising an operating member (447) movable between a first position and a second position for moving the housing (419) between said first and, respectively, second positions, the operating member (447) being movable out of said second position in a release direction, the connector (454) being connectable to the power plug (405) and disconnectable from the power plug (5; 405) in directions transverse to said release direction and keeping the operating member (447) locked in the second position when connected to the power plug (405).

23. A system for distributing electricity inside a building comprising a rail (101; 401) according to any one of the claims 1-12 and at least a power plug (5; 1-5; 205; 305; 405) according to any one of the claims 13-21 connectable to the rail (101; 401) or a combination according to claim 22 connectable to the rail (101; 401).