WO2009027469A1

WO2009027469A1 - A claw

Info

Publication number: WO2009027469A1
Application number: PCT/EP2008/061308
Authority: WO
Inventors: Nikolaj H Jensen; Per Jensen
Original assignee: Schneider Electric Danmark A/S
Priority date: 2007-08-29
Filing date: 2008-08-28
Publication date: 2009-03-05
Also published as: EP2193583A1; DK200701227A; DK177073B1

Abstract

A claw (1) for electrical wiring accessories (5) and comprising a clamp plate (2) with a clearance hole (3) for receiving a screw (4) to the effect that the clamp plate (2) is turnable about a rear edge (6) facing towards the electrical wiring accessory (5) and supported in a seating (7). A nut (9) is provided for receiving said screw (4) and for meshing with a protrusion (13) on the claw (1) at a distance from said rear edge (6) to the effect that the claw (1) is pulled off the sidewall when the screw is screwed backwards.

Description

A claw

The invention relates to an expanding claw for electrical wiring accessories for fastening the electrical wiring accessory in a wall box having a sidewall for cooperating with the claw, and wherein the claw is embedded in the electrical wiring accessory and comprises a clamp plate with a clearance hole for receiving a screw, said clamp plate being integral with claw legs that extend outwards from the clamp plate in a direction towards the bottom of the electrical wiring accessory; and comprises a nut below the clamp plate for receiving said screw to the effect that the claw is dug forcefully into the sidewall of the wall box when the screw is screwed in one direction.

Such claw is known from EP 1187285. The drawback of that prior art is that no means are provided for withdrawing the claw in case of dismounting of the electrical wiring accessory.

From DE 20013233 U1 a claw is known that has a return function which is provided by means of a loose spring that has, however, several drawbacks. An increase in the number of separate parts to be assembled will increase the cost of the product accordingly. Besides it is a known problem that if one spreads the claws too much - eg if mounting the product in a box of too large diameter - then the spring is strained and ceases to work.

All of the above drawbacks are avoided merely by configuring the claw which is known from EP 1187285 with a return function which is accomplished by hinging the claw relative to the electrical wiring accessory so that the clamp plate can move neither inwards nor outwards along the axial direction of the fastening screw. The spring known from DE 20013233 U1 is avoided, and it is at all time ensured that one is able to release the claw from its engagement with the wall box. Other structures are also known, such as eg taught in German patents DE 40 28 766 and DE 197 54 644. By this prior art, the fastening screw is configured to cooperate with a thread in the electrical wiring accessory and the fastening screw cooperates with a narrowed portion underneath the screw head, whereby the tips of the claw can be influenced in a direction inwards towards and away from a sidewall in which the electrical wiring accessory is to be mounted. This prior art is associated with the drawback that the underside of the screw head is caused to cooperate with an inclining face of the claw to the effect that the screw is influenced sideways. Moreover, the screw head moves inwards, when the screw is screwed. Both of these circumstances make the mounting process difficult due to it being difficult to hold the screw driver in the recess.

It is the object of the invention to provide a claw, wherein all of the above- referenced drawbacks are avoided.

This object is accomplished in that clamp plate is hinged to the electrical wiring accessory such that, at the hinge, it is not movable in the axial direction of the screw, said nut being configured for meshing with a protrusion on the claw at a distance from said hinge to the effect that the claw legs are pulled off the sidewall when the screw is screwed in the opposite direction.

The use of a nut which is able to directly influence the clamp plate when the electrical wiring accessory is to be fastened also enables the nut to push the claw off the wall of the box when the screw is unscrewed, due to the nut meshing with the claw at a distance from said rear edge of the clamp plate which faces towards the electrical wiring accessory, whereby a torque is provided that causes the claw to disengage from the box wall. These advantages can be obtained simultaneously with the underside of the screw head being able to cooperate with a plane face of the electrical wiring accessory and without the screw having to move in the longitudinal direction, whereby controlling of the screw driver during the mounting procedure of the electrical wiring accessory according to the invention is considerably facilitated compared to the accomplishments of the prior art.

According to one embodiment the claw is in the shape of a pair of legs extending past the nut to each side thereof. There are several ways in which the nut is able to mesh and cooperate with the clamp plate to the effect that the claw is released from the wall when the screw is unscrewed. For instance, the nut may have at least one protrusion for meshing with a cooperating protrusion on a leg, but preferably two pairs of mutually meshing protrusions are provided on the legs and the clamp plate, respectively.

The nut may also be bent around for cooperating with the side of the clamp plate that faces away from said rear edge, or the legs may have a pair of protrusions that face towards each other at a mutual distance to the effect that the clearance of the nut is restricted between the protrusions and the side of the clamp plate that faces towards the bottom of the electrical wiring accessory.

Instead of the claw comprising a pair of legs, it may be configured as a plate extending from the clamp plate at a distance there from towards said edge on the clamp plate and extending in a direction towards the bottom of the electrical wiring accessory. The claw may also have other configurations, and it is thus within the scope of the invention to configure the nut, the clamp plate and the claw such that the nut is able to cooperate with the clamp plate and/or the claw and cause the claw to move away from the box wall when the screw is unscrewed. The invention will now be explained in further detail with reference to the following description of exemplary embodiments, reference being made to the drawing, wherein:

Figure 1A is a perspective view of a electrical wiring accessory featuring an embodiment of a claw according to the invention;

Figure 1 B shows a view of the electrical wiring accessory from Figure 1A disassembled from a wall box;

Figures 2A and 2B are perspective views of details of the embodiment of the claw shown in Figure 1 ;

Figures 3A and 3B show in detail how an embodiment of the invention of the claw cooperates with the electrical wiring accessory, while

Figures 4-7 show other embodiments of the claw according to the invention.

The invention is intended for electrical installation equipment or electrical wiring accessory, in particular of the kind where a electrical wiring accessory is to be clamped securely in a box 25, see Figure 1 B, eg in a wall or a ceiling. The electrical wiring accessory may comprise electrical outlets, switches, or other electrical wiring accessory which is not limiting to the invention.

The electrical wiring accessory 5 shown in Figure 1A has a claw (1 ) in two opposite sides, wherein only the claw in the one side is shown in the figure. The claw comprises a clamp plate 2 which is integral with a pair of claw legs 11 having, at their ends, protruding tips 8. The clamp plate 2 has a clearance hole 3 for receiving a screw 4, the thread of which cooperates with a thread in a nut 9. The nut 9 has protrusions 12 for meshing with protrusions 13 on the legs 11. Moreover the clamp plate 2 has a rear edge 6 which is configured for being received in a seating 7 in the electrical wiring accessory as will be explained in further detail below. Figures 2A and 2B show the claw in two different positions. It is noted that, in the preferred embodiment, the fastening screw 4 is fixated against axial movement within the electrical wiring accessory 5. When the screw 4 is tightened, it will pull the nut 8 upwards (the arrow P1 ), whereby the claw legs 11 are forced outwards due to the rear edge 6 being journalled in a seating 7 in the electrical wiring accessory.

When the screw 4 is unscrewed (Figure 2B), the nut 9 will be pressed downwards (Figure 2B) and the protrusion 12 of the nut 9 will mesh with the protrusions 13 to the effect that the claw legs 11 are forced away from the wall of the box in which the electrical wiring accessory 5 is arranged.

This will appear in further detail from figures 3A and 3B, where the nut 9 is shown in engagement with the clamp plate 2. Moreover, a seating 7 in the electrical wiring accessory receives the rear edge 6 mentioned above, to the effect that the legs of the clamp plate turn about said edge when the nut influences the clamp plate 2 via the protrusions 12.

Figure 4 shows a modified embodiment of the claw, wherein the clamp plate 2 has a protrusion 14 for meshing with a hole 21 in a nut 17. It will readily be understood that, in this way, the nut 17 is able to control the clamp plate 2 and its accompanying claws.

Figure 5 shows a further embodiment, where the claws are provided with a pair of protrusions 15 that face towards each other, and wherein the associated nut 18 is configured with matching, oblong protrusions 20 to the effect that said control is also accomplished. In Figure 6, the protrusions 15 shown in Figure 5 are replaced by a number of oblong, bent-in portions 25, and it will readily be understood how the nut 22 is able to control the claws.

The invention is not limited to the claw comprising a pair of legs. Figure 7 shows an embodiment wherein the clamp plate 2 is integral with a leg 16 having a pair of protruding tips 19. The associated nut 23 has protrusions 24 which, when the parts are mounted, extend across the clamp plate 2 and thus pull it downwards and hence pull the tips 19 of the claw off the box wall when the screw is screwed home.

Claims

P a t e n t c l a i m s

1. A claw for electrical wiring accessories for fastening the electrical wiring accessory in a wall box having a sidewall for cooperating with the claw, and wherein the claw is embedded in the electrical wiring accessory and comprises a clamp plate (2) with a clearance hole (3) for receiving a screw (4), said clamp plate being integral with claw legs (11 ) that extend outwards from the clamp plate in direction towards the bottom of the electrical wiring accessory; and comprises a nut (9) below the clamp plate for receiving said screw to the effect that the claw is dug forcefully into the sidewall of the wall box when the screw is screwed in one direction, characterised in that the clamp plate (2) is hinged to the electrical wiring accessory such that, at the hinge, it is not movable in the axial direction of the screw, said nut being configured for meshing with a protrusion (13) on the claw at a distance from said hinge to the effect that the claw legs (11) are pulled off the sidewall when the screw is screwed in the opposite direction.

2. A claw according to claim 1 , characterised in that the clamp plate (2) is turnable about a rear edge (6) hinged in a seating (7) in the electrical wiring accessory (5).

3. A claw according to claim 1 or 2, characterised in that the claw legs extend past the nut (9) to each side thereof.

4. A claw according to claim 3, characterised in that the nut has at least one protrusion (12) for meshing with a corresponding protrusion (13) on a claw leg.

5. A claw according to claim 4, characterised in that the nut has two protrusions (12) for meshing with respective protrusions (13) on the legs at a distance from said edge (6) of the clamp plate.

6. A claw according to claim 3, characterised in that the nut has at least one protrusion (21 ,24) for cooperating with the clamp plate (2) at a distance from said rear edge (6).

7. A claw according to claim 3, characterised in that the legs have a pair of protrusions (15) facing towards each other at a mutual distance to the effect that the clearance of the nut (18) is restricted between the protrusions (15) and the side of the clamp plate that faces towards the bottom of the electrical wiring accessory.

8. A claw according to claims 3-7, characterised in that the legs have tips (8) for cooperating with the sidewall of the box.

9. A claw according to claim 1 or 2, characterised in that the claw is in the shape of a leg (16) that extends outwards from the clamp plate at a distance from the edge of the clamp plate that faces towards the electrical wiring accessory and extends in a direction towards the bottom of the electrical wiring accessory.

10. A claw according to claim 9, characterised in that the plate has protruding tips (19) for cooperating with the sidewall of the box.