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(11) | EP 0 693 654 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Device for fixing bulb-sockets to the base of lamps |
| (57) Device for fixing bulb-sockets to the base of lamps, which comprises a body (2) made
of electrically insulating material that has an elongated shape and is longitudinally
crossed by a passage (3) for an electric power cord (4). The body (2) is connected,
with one of its longitudinal ends, to the cap (5) of the bulb-socket (6) to be assembled,
and is provided, on its lateral surface, with push-fitting engagement means (9,12a,12b)
engageable inside a hole (7) formed in the lamp base (8). |
[0002] It is known that a tubular body, known as stem, is currently used to fix bulb-sockets to the base of lamps, said tubular body being usually made of metal, inserted in a hole appropriately provided in the base of the lamp, and locked inside said hole by glueing or by means of two self-tapping screws.
[0003] The cap of the bulb-socket, that is to say, the end of the bulb-socket to be associated with the base of the lamp, is then assembled and is locked on the stem by glueing or with a special rotation-preventing device optionally provided on the cap of the bulb-socket.
[0004] The power cord of the lamp passes through the stem; if said stem is metallic, it requires the use of insulators in order to achieve the correct electrical insulation of the lamp body.
[0005] Furthermore, with currently commercially available bulb-socket fixing devices it is necessary to provide for a cord clamp that prevents the sliding of the cord with respect to the base of the lamp, discharging thereonto the traction prescribed by statutory provisions regarding luminaires.
[0006] Assembly of the bulb-socket to the base of lamps with currently commercially available fixing devices is therefore relatively complicated and considerably affects the overall assembly time of the lamp and consequently the production costs.
[0007] The aim of the present invention is to provide a device for fixing bulb-sockets to the base of lamps very simply and quickly and for effectively clamping the lamp power cord, offering the greatest assurances in terms of electrical insulation of the lamp body.
[0008] Within the scope of this aim, an object of the invention is to provide a device which, by reducing the time required to assemble the bulb-socket to the base of lamps, allows considerable savings in their overall production costs.
[0009] This aim, these objects, and others which will become apparent hereinafter are achieved by a device for fixing bulb-sockets to the base of lamps, characterized in that it comprises a body made of electrically insulating material that has an elongated shape and is longitudinally crossed by a passage for an electric power cord, said body being connected, with one of its longitudinal ends, to the cap of the bulb-socket to be assembled, and being provided, on its lateral surface, with push-fit engagement means engageable inside a hole formed in the lamp base, means for clamping said electric power cord, when said body is inserted into said hole formed in the lamp base, being provided in said passage.
[0010] Further characteristics and advantages will become apparent from the following detailed description of a device according to the invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein:
Fig. 1 is a partially sectional view, taken along a longitudinal plane, of the device according to the present invention, applied to the base of a lamp;
Fig. 2 is a perspective view of the device according to the invention;
Fig. 3 is a top plan view of the cap of the bulb-socket with the device according to the invention;
Fig. 4 is a bottom plan view of the cap of the bulb-socket with the device according to the invention;
Fig. 5 is a sectional view of Fig. 4, taken along the plane V-V;
Fig. 6 is a sectional view of Fig. 5, taken along the plane VI-VI;
Fig. 7 is an enlarged-scale sectional view of Fig. 3, taken along the plane VII-VII; and
Fig. 8 is a sectional view of Fig. 6, taken along the plane VIII-VIII.
[0011] With reference to the above figures, the device according to the invention, generally designated by the reference numeral 1, comprises a body 2, made of electrically insulating material, that has an elongated shape, preferably cylindrical, and is crossed axially by a passage 3 for an electric power supply cord 4. The body 2 is connected to the cap 5 of a bulb-socket 6 and is preferably produced by directly molding synthetic material monolithically with the cap 5 of the bulb-socket 6.
[0012] The body 2 has, on its lateral surface, push-fitting engagement means engageable inside a hole 7 formed in the base 8 of the lamp.
[0013] Conveniently, the push-fitting engagement means comprise teeth 9 formed on the lateral surface of the body 2 and shaped so as to facilitate the insertion of the body 2 inside the hole 7 and contrast its extraction from said hole 7 after insertion.
[0014] The teeth 9 run substantially along the entire lateral surface of the body 2, with the exception of two diametrically opposite flat regions 10a and 10b. Ribs 11 are provided at said regions 10a and 10b, run parallel to the axis 2a of the body 2, and contrast the rotation of the body 2 inside the hole 7.
[0015] The push-fitting engagement means comprise two flaps 12a and 12b protruding from the lateral surface of the body 2 in two mutually diametrically opposite regions, preferably offset by 90o with respect to the regions 10a and 10b, about the axis 2a of the body 2. The flaps 12a and 12b are flexible and are arranged at openings 13a and 13b formed in the lateral surface of the body 2, so that the flaps 12a and 12b, rigidly coupled to the remaining part of the body 2 at their lower end, can flex, by virtue of their elasticity, towards the axis 2a of the body 2 when the body 2 is inserted into the hole 7.
[0017] Advantageously, it is possible to provide, on the outer surface of the flaps 12a and 12b, a stiffening rib 23 extending from the side of the lower end of the corresponding flap to the remaining part of the body 2.
[0018] The ribs 11 and the ribs 23, except for the interruption constituted by the openings 13a and 13b, extend to the upper end of the body 2, that is to say, the end of the body 2 connected to the cap 5 of the bulb-socket 6.
[0019] Furthermore, the device according to the invention comprises means for clamping the electric power cord 4 which are provided so that the electric power cord is locked inside the body 2 when said body 2 is inserted into the hole 7.
[0020] Advantageously, said means for clamping the power cord 4 are constituted by teeth 15 formed on the surface of the flaps 12a and 12b that is directed towards the axis 2a of the body 2. Said teeth 15 are shaped so as to contrast the extraction of the electric power cord 4 in the opposite direction with respect to the bulb-socket 6. The teeth 15 formed on the flaps 12a and 12b can be arranged mutually opposite or can be offset, so as to constitute a sort of labyrinth when the flaps 12a and 12b are mutually close.
[0021] Conveniently, in order to facilitate the insertion of the body 2 into the hole 7, the end of the body 2 that lies opposite to the cap, that is to say, the end to be inserted into the hole 7, has a tapering portion 16.
[0022] Mutually diametrically opposite flat portions can be provided on the side walls of the hole 7, said portions being adapted to couple to the regions 10a and 10b of the body 2 so as to effectively contrast the rotation of the body 2 with respect to the base 8 of the lamp after its insertion into the hole 7.
[0023] The cap 5, as regards its part lying outside the base 8, can be configured in a per se known manner and is not described in more detail for the sake of simplicity.
[0024] Assembly of the bulb-socket provided with the device according to the invention is as follows.
[0025] The power cord 4 is inserted beforehand through the passage 3 formed in the body 2. The body 2 is then inserted by pushing inside the hole 7. The insertion of the body 2 into the hole 7 produces the push-fitting engagement of the teeth 9 and of the teeth 14 against the side walls of the hole 7, ensuring the push-fitting locking of the body 2 inside the hole 7 and thus firmly coupling the cap 5 to the base 8 of the lamp.
[0026] The insertion of the body 2 inside the hole 7 also produces the flexing of the flaps 12a and 12b towards the axis of the body 2 and thus also clamps the electric power cord 4 inside the body 2.
[0027] In practice it has been observed that the device according to the invention fully achieves the intended aim, since it allows to assemble the bulb-cocker on the base of lamps in very short times, simply requiring push-fitting insertion, and simultaneously clamping the electric power cord, at the same time ensuring optimum electrical insulation.
[0028] In practice, the materials employed, so long as they are compatible with the specific use, as well as the dimensions, may be any according to the requirements and the state of the art.
[0029] Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.
1. A device for fixing bulb-sockets to the base of lamps, characterized in that it comprises
a body (2) made of electrically insulating material that has an elongated shape and
is longitudinally crossed by a passage (3) for an electric power cord (4), said body
(2) being connected, with one of its longitudinal ends, to the cap (5) of the bulb-socket
(6) to be assembled, and being provided, on its lateral surface, with push-fit engagement
means (9,12a,12b) engageable inside a hole (7) formed in the lamp base (8), means
(15) for clamping said electric power cord, when said body is inserted into said hole
(7) formed in the lamp base (8), being provided in said passage (3).
2. A device according to claim 1, characterized in that said body (2) is monolithic with
said cap (5)) of the bulb-socket (6).
3. A device according to the preceding claims, characterized in that said body (2) has
a substantially cylindrical shape and in that said push-fitting engagement means comprise
teeth (9) formed on the lateral surface of said body (2).
4. A device according to claim 1, characterized in that said push-fitting engagement
means (9,12a,12b) comprise at least one flap (12a,12b) protruding from the lateral
surface of said body (2) and flexing towards the axis (2a) thereof during the insertion
of said body (2) into said hole (7) formed in the lamp base (8).
5. A device according to claim 4, characterized in that the outer surface of said flap
(12a,12b) that is adapted to engage the side walls of said hole (7) is provided with
teeth (14).
6. A device according to claim 4, characterized in that said flap (12a,12b) is arranged
at an opening (13a) formed in the lateral surface of said body.
7. A device according to claims 1 and 4, characterized in that said means for clamping
the power cord comprise teeth (15) formed on the surface of said flap (12a,12b) that
is directed towards the axis (2a) of said body (2).
8. A device according to claim 1, characterized in that said body (2) has, on its lateral
surface, axial ribs (11) contrasting the rotation of said body (2) inside said hole
(7) formed in the lamp base (8).
9. A device according to claim 4, characterized in that said flap (12a,12b) has a stiffening
rib (23) on its outer lateral surface.
10. A device according to claims 4 and 9, characterized in that said flap (12a,12b) is
connected to said body (2) by its lower end and in that the stiffening rib (23) of
said flap extends from said lower end of the flap on the lateral surface of said body
(2).
11. A device according to claim 4, characterized in that said at least one flap comprises
two diametrically opposite flaps (12a,12b) protruding from the lateral surface of
said body (2).
12. A device according to claim 4, characterized in that said body (2) has, on its lateral
surface, two flat regions (10a,10b) that are mutually diametrically opposite and are
angularly offset with respect to said flaps (12a,12b) about the axis (2a) of said
body (2), said flat regions being arrangeable, when said body is inserted into said
hole (7) formed in the lamp base (8), at two flat regions formed correspondingly on
the side walls of said hole (7).
13. A device according to one or more of the preceding claims, characterized in that said
teeth formed on the internal surface of said flaps (12a,12b) are oppositely orientated.
14. A device according to claim 7, characterized in that said teeth (15) formed on the
internal surface of said flaps (12a,12b) are offset so as to form a labyrinth when
said flaps (12a,12b) are moved towards the axis (2a) of said body (2).