GB2307361A

GB2307361A - Lamp holder for a tubular lamp

Info

Publication number: GB2307361A
Application number: GB9624049A
Authority: GB
Inventors: Eric Dumont
Original assignee: Legrand SNC
Current assignee: Legrand SNC
Priority date: 1995-11-20
Filing date: 1996-11-19
Publication date: 1997-05-21
Anticipated expiration: 2016-11-19
Also published as: FR2741481A1; DE19648079A1; GB9624049D0; ITTO960930A1; IT1289663B1; FR2741481B1; ITTO960930A0; GB2307361B

Description

2307361 1 LAMP HOLDER FOR A TUBULAR LAMP The invention relates generally

to lamp holders for tubular lamps of the type comprising a cover made from insulating material, and a contact block which is mounted in a moveable manner in the cover in opposition to elastic means, projects from the cover through an aperture in the cover and has at least one female plug socket.

The tubular lamp to be mounted may be a discharge lamp, for example a fluorescent lamp, the lamp caps of which are double-pole lamp caps, in view of a possible pre-heating of its electrodes on the one hand, and which on the other hand is intended for a light fitting in an explosible atmosphere.

In a case such as this, the contact block of the lamp holder has two female plug sockets, that is to say one for each of the pins of the lamp cap of such a lamp.

However, having regard for the standard precautions governing any operation in an explosible atmosphere, various requirements have to be satisfied.

Firstly, leakage paths have to be taken into account.

For this reason, up until now the lamp holder has been equipped with two screw terminals for its wiring.

Because of this, up until now in order to have all the necessary insulation, not ordy was a plate of insulating material placed on said terminals after wiring, but this plate was also in turn covered with a layer of heat-fusible insulating material and the gap inevitably existing around its periphery was completely covered with this.

In the same way, as the cover was up until now constituted by two pieces, one of which formed a tube cap and the other formed a cover at the back of said tube cap, it was necessary to arrange a seam line of this heat-fusible insulating material at the join between the tube cap and the cover in order to provide all the required insulation.

The necessary operations for using the lamp holder are correspondingly complicated.

Furthermore, when no pre-heating of the electrodes of the lamp is 2 provided, the wiring of the lamp holder has to include the provision of a shunt from one of its terminals to the other, prior to them being covered by a plate of insulating material and by a layer of heat-fusible insulating material, and in practice the setting-up of this shunt is done outside the cover.

According to the invention there is provided a lamp holder for a tubular lamp comprising a cover made from insulating material, and at least one contact block which is mounted in a moveable manner in the cover in opposition to elastic means, projects from the cover through an aperture in the cover and has at least one female plug socket wherein the cover is formed of two pieces, one of these pieces being a shell in the general shape of a pocket which comprises the aperture by virtue of which the contact block is introduced, while the other forms a plug-in unit which is engaged in the shell through the opening thereof, and the base of which is on the side opposite the aperture.

Thus the leakage paths are advantageously respected by the cover itself, without it being necessary to join any plate of insulating material to it and/or to apply any layer of insulating material to it to cover any possible gaps.

Furthermore, and according to a second feature, the lamp holder according to the invention is also generally characterised in that the contact block has two female plug sockets and a shunt is provided to produce an electrical connection between the two contacts subjacent to these female plug sockets, said shunt being inside the cover itself.

According to a preferred embodiment, in practice this involves a metal plate which is arranged facing the aperture in the cover, on the base of the plug-in unit contained therein, and is fitted, preferably integrally, with at least one lug suitable for the lamp holder wiring.

The operations for using the lamp holder according to the invention are advantageously simplified.

It is indeed sufficient to provide its wiring by joining, preferably by crimp connection of a section of electric cable to the lug of the metal plate forming the shunt, then, after having placed it in the plug-in unit, to engage said plug-in unit and the attached contact block in the shell until the end position therein is reached.

3 These operations can be carried out in situ.

However, as a variation, they can also be carried out in the workshop, the lamp holder being previously fitted with a section of electric cable suitable for its connection.

The invention is diagrammatically illustrated by way of example in the accompanying drawings attached, in which:

Figure 1 is a perspective view of a lamp holder according to the invention shown in place and seen from above; Figure 2 is another perspective view, in place and seen from the bottom; Figure 3 is an exploded perspective view of the lamp holder according to the invention, according to the orientation of Figure 2; Figure 4 is a part view, shown in a larger scale, of a transverse section according to the line WAV in Figure 3; Figure 5 is a perspective view of the metal plate used to form a shunt, shown crimp connected onto a section of electric cable; Figure 6 is a part view shown in a larger scale, of a section through said plate, according to the line VI-V1 in Figure 5; Figure 7 is a view of an elevation, shown in a larger scale, from the front, of the plug-in unit comprised by the cover of the lamp holder according to the invention, shown on its own; Figure 8, shown in an even larger scale, is a part sectional view of said plug-in unit, according to the line VIII-VIII in Figure 7.

As shown in these drawings, a lamp holder 10 generally comprises, in a manner known per se, a cover 11 made from insulating material, and at least one contact block 12 which is mounted in a moveable manner in the cover 11 in opposition to elastic means 13 which will be explained later, and projects from said cover 11 through an aperture 14 in said cover, and has at least one female plug socket 15.

In the embodiment shown by way of example, only one contact block 12 is provided. In practice, the tubular lamp 16 to be received, as shown by dashed lines in Figure 1, is a lamp with double-pole lamp caps 17, that is to say with lamp 4 caps 17 each provided with two pins 18, as can be seen from the one shown in Figure 1, the contact block 12 having two female plug sockets 15 parallel to one another at a distance apart from one another, each respectively providing access to two subjacent contacts 19.

In a manner known per se, the elastic means 13 associated with this contact block 12 are formed by two metal springs 20 of the helical spring type, which are configured at their extremity such as to themselves constitute the contacts 19.

Said contacts 19 thus extend axially with respect to the female plug sockets 15 and thus with respect to the contact block 12.

They are each constituted by a single piece, this being a metal spring 20.

In practice, the contact block 20 which itself is made from insulating material is generally bell-shaped with respect to the contour of the aperture 14 of the cover 11, and here and there along the free edge of its lateral skirt 21 has outwardly projecting lugs 22 for retaining it in the cover 11.

In a manner generally known per se, the cover 11 on the one hand generally forms an infrastructure 24 at its foot, the plan-view contour of which is generally quadrilateral and in which the electrical connection of the lamp holder 10 is done according to the arrangements which will be described hereinafter, and on the other hand projecting from said infrastructure 24, but set back with respect thereto on at least three of its edges, a superstructure 25 into which the contact block 12 is introduced, having a shoulder 26 transversally at the juncture between the infrastructure 24 and the superstructure 25.

In practice, and as shown in Figures 1 and 2, the lamp holder 10 is engaged by means of the superstructure 25 of its cover 11 in a support 27, for example a simple plate, by virtue of a cut-out 28 in said support 27, until the shoulder 26 of said cover 11 abuts against the support 27 and, according to the measures described in more detail hereinafter, is appropriately fixed to said support.

The cover 11 is formed by two pieces, one of these pieces being a shell 30 in the general shape of a pocket which comprises the aperture 14 through which the contact block 12 projects, while the other forms a plug-in unit 31 which is engaged in the shell 30 through the opening 32 thereof, and the base 33 of which is on the side opposite the aperture 14.

In the embodiment shown, the opening 32 in the shell 30 is at the foot 5 of the lamp holder 10, provided in the bottom surface of the infrastructure 24.

In practice it extends over the whole perimeter of said infrastructure 24.

The shell 30 itself thus generally forms both the infrastructure 24 and the superstructure 25.

Taken integrally with the shoulder 26, on the one hand in order to define the infrastructure 24 said shell has a lateral wall 34 with a quadrilateral contour and on the other hand to define the superstructure 25, a front wall 35 which comprises the aperture 14, a lateral wall 36 which is generally arch-shaped, and a rear wall 37 which is a continuation of the corresponding portion of the lateral wall 34 of the infrastructure 24.

In the embodiment shown, the lateral wall 34 of the infrastructure 24 has, set back along each of its edges, on a part of the height thereof, steps 38 projecting into its internal contour, providing the abutment for the plug-in unit 31.

This lateral wall 34 further locally comprises ribs 39, projecting into its internal contour, to provide guidance for the plug-in unit 31 taking into account the difference in the section thereof with respect to the infrastructure 24.

To simplify the engagement of the plug-in unit 31, these ribs 39, only one of which is shown in the drawings, more precisely in Figure 3, are tipped with a chamfer 40 along their leading edge.

The lateral wall 34 of the infrastructure 24 is moreover locally provided at the front with two notches 41 along its bottom edge, in the form of arches which both form part of the opening 32, and which are both suitable intended for the passage through of a section of electric cable 42.

In the embodiment shown, the shell 30 locally provides a housing 43 for a fixing means 45 for fixing the assembly to the support 27.

In practice, said housing 43 is in the infrastructure 24, and more precisely in the median area of the portiorb of the front of its lateral wall 34, 6 projecting into the internal volume of the infrastructure 24 and opening out by means of a bore 46 onto the shoulder 26, Figure 4. In practice also, the fixing means 45 is a simple self-threading screw which bites directly into the internal surface of the housing 43.

The plug-in unit 31 externally has an overall volume generally complementary to that of the interior of the shell at the level of the superstructure 25.

Its base 33 duplicates the rear wall 37 of the shell 30 in every respect.

Apart from its base 33, the plug-in unit 31 comprises a rim 47, the internal extremity of which is in the shape of an arch in the manner of the lateral wall 36 of the shell 30 defining the superstructure 25, and the height of which is substantially equal to that of said lateral wall 36, being, however, slightly less than that of said wall.

The plug-in unit 31 further comprises, at its exterior extremity, a end plate 48 which extends perpendicularly with respect to its base 33 and to the straight parts of its rim 47, and by means of which it covers the opening 32 of the shell 30.

The height of this end plate 48 with respect to the base 33 is therefore above that of the rim 47.

For guiding the contact block 12, the plug-in unit internally comprises at least one wall 49 set back with respect to its rim 47.

In practice, in the embodiment shown, three walls 49 are provided, that is to say two lateral walls 49A and one median wall 49B.

The lateral walls 49A, which are curved, are centred on the axis of the aperture 14, and form part of bosses 50 projecting into the interior, which the wall 47 forms locally.

The median wall 4913, which is planar and has three ribs 51, that is to say one alone, each of its lateral edges and one in its median area to prevent the contact block 12 being locked in the inserted position, is insulated and to keep it in place is provided with a stiffening rib 52 at its rear.

In order to lay at least one section of electric cable 42 and in practice in order to possibly lay two sections of electric cable 42, the plug-in unit 31 comprises 7 a plurality of internal partitions in arrangements which are in practice synunetrical to one another with respect to the median longitudinal plane of the assembly, Figure 7.

There is firstly a partition 54 which extends substantially according to this median longitudinal plane, and which is divided up by partitions 55.

This partition 54 is extended by a trapeze-shaped partition 56.

There are then partitions 57 which extend from the straight parts of the edge 47, dividing them up.

There are lastly partitions 58 which extend from the end plate 48, dividing it.

In the embodiment shown there are latching means 60, 61 between the shell 30 and the plug-in unit 31.

In practice, these latching means 60, 61 comprise on the one hand an elastically deformable tab 60 on the shell 30 which is integral with the rear wall 37 of said shell 30, and is formed by virtue of a local cut-out 62 therein and which is prolonged according to the median longitudinal plane of the assembly and extends from its base to its free end in the direction of engagement of the plug- in unit 31, and on the other hand a notch 61 on the plug-in unit 31 which projects transversally at the bottom of the base 33 of said plug-in unit 31, being preceded by a chamfer 63, and beneath which the elastically deformable tab 60 of the shell 30 engages.

The relative fixing of the plug-in unit 31 with respect to the shell 30 is thus done advantageously without any auxiliary fixing means.

For possible dismantling, the rear wall 37 of the shell 30 forms a groove 64 facing its local cutout 62 which, starting from the opening 32, provides access to the elastically deformable tab 60.

In a manner known per se, a shunt 65 is provided for establishing an electrical connection between the two contacts 19 subjacent to the contact block 12.

The shunt 65 is provided in the interior of the cover 11.

In the embodiment shown, said shunt 65 is formed by a metal plate which is arranged opposite the aperture 14 of the cover 11 and rests on the base 33 of the plug-in unit 31 belonging thereto.

8 The springs 20 forming the contacts 19 therefore bear directly upon said metal plate and they themselves directly establish an electrical connection between said contacts 19 and said plate.

In the embodiment shown, the metal plate forming the shunt 65 comprises a boss 67 for each of the metal springs 20, as can be seen better from one shown in Figure 6, on which said metal spring 20 is engaged by means of its end opposite the end forming a contact 19, in order to centre it.

In practice, said boss 67 is hollow and tubular and is formed by virtue of piercing.

In the embodiment shown, the cover 11 is provided with at least one projecting pin 68 for retaining the metal plate forming the shunt 65, with which said metal plate is in contact by means of one of its bosses 67.

In practice there are two pins 68, that is to say one for each boss 67, and said pins 68 project from the base 33 of the plug-in unit 31.

In the embodiment shown, the pins 68 are pointed at their ends to facilitate the positioning of the metal plate forming the shunt 65.

Lastly, in the embodiment shown said metal plate is fitted with at least one lug 70.

In practice, for reasons of symmetry, said plate is fitted with two lugs 70 and these are both integral with it.

During assembly, one of said lugs 70 is crimped onto the end of the metal core of the section of electric cable 42 which is preferably stripped, and the sub-assembly 71 formed in this way is fitted into the plug-in unit 3 1, the metal plate forming the shunt 65 is inserted between the walls 49A, 49B thereof, engaging on the pins 68, and the section of electric cable 42 is lead between the partitions 55, 56, 57, 58 of said plug-in unit 31 until it backs onto its end plate 48 and projects beyond it.

After positioning of the metal springs 20 constituting the elastic means 13, and of the contact block 12, and after restraining said elastic means 13, the plug-in unit is engaged in the shell 30 in the direction of the arrow F in Figure 3 until it locks into said shell 30 by means of the latching means 60, 61 provided for 9 this purpose.

The section of electric cable 42 then projects from the assembly by virtue of the corresponding notch 41 in the infrastructure 24 of the shell 30.

The lamp holder 10 constituted in this manner is then ready to be put in place on the support 27.

In the aforementioned it has been supposed that the lamp holder 10 comprises only one contact block 12.

However, for a double, triple or other mounting it can comprise two or more contact blocks 12 at a distance from one another.

In such a case there can be one plug-in unit 31 per contact block 12 for a common shell 30.

As a variation, a common plug-in unit 31 can be provided for at least two contact blocks 12, indeed there can be just one plug-in unit 31 for all of the contact blocks 12.

Together with this, the metal plates forming the shunts 65 are preferably arranged successively connected one after the other, for example by means of smaller sized tongues.

According to a development of this arrangement, said plates can, in practice, be connected to one another in a divisible manner, the corresponding tongues comprising, transversally for example, a line of least resistance for this purpose.

By having a strip comprising a row of metal plates, it is possible in this case to only retain the metal plates necessary for the contact blocks 12 present.

As a variation, however, it can also be worthwhile to use one of the lugs 70 provided on such a metal plate in the embodiment shown for connecting one metal plate to another.

Claims

1. A lamp holder for a tubular lamp comprising a cover made from insulating material, and at least one contact block which is mounted in a moveable manner in the cover in opposition to elastic means, projects from the cover through an aperture in the cover and has at least one female plug socket wherein the cover is formed of two pieces, one of these pieces being a shell in the general shape of a pocket which comprises the aperture by virtue of which the contact block is introduced, while the other forms a plug-in unit which is engaged in the shell through the opening thereof, and the base of which is on the side opposite the aperture.

2. A lamp holder according to claim 1, wherein the cover forms an infrastructure through which the electrical connection of the assembly is carried out, and a superstructure through which the contact block is introduced, and the opening in the shell is in the bottom surface of the infrastructure.

3. A lamp holder according to claim 2, wherein the plug-in unit has externally an overall volume generally complementary to the interior of the shell at the level of the superstructure.

4. A lamp holder according to any one of claims 1 to 3, wherein the base of the plug-in unit duplicates the rear wall of the shell in every respect.

5. A lamp holder according to any one of claims 1 to 4, wherein apart from its base, the plug-in unit comprises a rim, the height of which is substantially equal to that of the lateral wall of the shell.

6. A lamp holder according to claim 5, wherein at the internal extremity of the plug-in unit, the rim is in the form of an arch, in the manner of the lateral wall of the shell.

11

7. A lamp holder according to claim 5 or claim 6, wherein the plug-in unit comprises at least one wall set back with respect to its rim for guiding the contact block.

8. A lamp holder according to any one of claims 1 to 7, wherein the plugin unit comprises on its external extremity an end plate whereby it covers the opening in the shell.

9. A lamp holder according to any one of claims 1 to 8, wherein the plugin unit comprises a plurality of internal partitions for laying at least one section of electric cable.

10. A lamp holder according to any one of claims 1 to 9, wherein for fixing the assembly to a support, the shell locally comprises a housing suitable for the introduction of a fixing means.

11. A lamp holder according to any one of claims 2 to 10, wherein the housing is provided in the infrastructure.

12. A lamp holder according to claim 10 or claim 11, wherein latching means are provided between the shell and the plug-in unit.

13. A lamp holder according to any of claims 1 to 12, wherein at least two contact blocks are provided at a distance apart from one another, and there is one 25 plug-in unit per contact block.

14. A lamp holder according to any of claims 1 to 12, wherein at least two contact blocks are provided at a distance apart from one another, and a common plug-in unit applies to at least two contact blocks.

15.

A lamp holder according to claim 14, wherein there is only one plug-in 12 unit for all of the contact blocks.

16. A lamp holder according to any one of claims 1 to 15, wherein the contact block has two female plug-in sockets and a shunt is provided to produce an electrical connection between the two contacts subjacent to said female- plug-in sockets, said shunt being in the inside of the cover itself.

17. A lamp holder according to claim 16, wherein the shunt is formed by a metal plate arranged opposite the aperture in the cover.

18. A lamp holder according any one of claims 16, 17, wherein the contacts are disposed axially and are each constituted by a single piece.

19. A lamp holder according to claim 18, wherein the elastic means connected to the contact block are formed by two metal springs of the helical spring type which are configured at their extremity such as to themselves constitute the contacts, said metal springs bearing directly upon the metal plate forming the shunt.

20. A lamp holder according to claim 19, wherein for each of the metal springs the metal plate forming the shunt comprises a boss on which such a metal spring is engaged.

21. A lamp holder according to claim 20, wherein to retain the metal plate forming the shunt, the cover comprises at least one projecting pin with which said metal plate is engages by means of one of the projections with which it is provided.

22. A lamp holder according to any one of claims 17 to 22, wherein the metal plate forming the shunt rests on the base of the plug-in unit.

23. A lamp holder according to any one of claims 17 to 22, wherein the 13 metal plate forming the shunt is fitted with at least one lug.

24. A lamp holder according to claim 23, wherein the lug is integral with the metal plate forming the shunt.

25. A lamp holder according to any one of claims 23, 24, wherein the metal plate forming the shunt is provided with two lugs.

26. A lamp holder according to any one of claims 17 to 25, wherein at least two contact blocks are provided at a distance apart from one another, and the metal plates forTning the corresponding shunts are joined one after another.

27. A lamp holder according to claim 26, wherein the metal plates forming the shunts are joined in a divisible manner.

28. A lamp holder substantially as hereinbefore described and illustrated with reference to the accompanying drawing.