Lamp holder with quick locking of electric power supply cord

Abstract: A lamp holder with quick locking of the electric power supply cord (10), which comprises a lamp holder body (2) in which there is, starting from one of its ends, a seat (4) that can be engaged by a lamp and a cap (3) that is associable with the opposite end of the lamp holder body (2). A passage (11) for an electrical power supply cord (10) is formed in the cap (3). The lamp holder body (2) has, proximate to its end that can engage the cap (3), a cavity (7) that is open toward the cap (3) and supports, in a central region, a block that carries the electrical terminals for fixing the cord (10). The cap (3) is provided with cord clamping means that can be activated by the assembly of the cap (3) with the lamp holder body (2). The cord clamping means comprises at least one wing (20) that is connected, at one of its ends, to the portion (12) of the cap (3) in which the cord passage (11) is provided, and has, in an intermediate region of its extension, a tooth (22) that protrudes toward the axis of the passage (11). The opposite end of the wing (20), upon assembly of the cap (3) with the lamp holder body (2), engages the side wall of the cavity (7) so as to achieve an elastic flexing of the wing (20) that makes the tooth (22) move toward the axis of the passage (11) in order to axially lock the cord (10).

Description: The present invention relates to a lamp holder with quick locking of its electric power supply cord. Lamp holders are known substantially constituted by a lamp holder body which is generally substantially cylindrical and in which there is, starting from one of its axial ends, a seat that is provided with threaded or bayonet-type engagement means and can be engaged by the lamp to be supported by means of the lamp holder. A cap is generally detachably associated on the opposite end of the lamp holder body and is crossed centrally by a passage for the electric power supply cord of the lamp holder. In many kinds of lamp holder, the cap is fitted to the lamp holder body by snap-acting mutual engagement means. These snap-acting mutual engagement means is generally constituted by two tabs that can flex elastically toward or away from the axis of the cap, which when the lamp holder is assembled coincides with the axis of the lamp holder body. Each one of said tabs has, at its free end, a tooth defining an axial shoulder for the cap that can engage a corresponding axial shoulder formed on a portion of the side wall of the lamp holder body. Substantially, by an axial movement of the cap with respect to the lamp holder body and by utilizing the elasticity of these tabs, the axial shoulders provided on the teeth of the tabs are made to move past the axial shoulders provided on the side wall of the lamp holder body and are then made to engage, by elastic reaction of the tabs, which move toward the axis of the lamp holder body, the axial shoulders provided on the side wall of the lamp holder body. In many kinds of lamp holders there are means for clamping the electric power supply cord. This clamping means is designed to prevent any pulling forces applied to the cord from being transmitted to the electrical terminals, altering the electrical connections and therefore generating imperfect operation of the lamp holder which might also cause dangerous situations for the user. The means for clamping the electrical power supply cord is usually provided in lamp holders for hanging lamps, in order to prevent the weight of the lamp holder, of the lamp proper, and of any accessories such as lampshades supported by the lamp holder, from bearing fully on the terminals for fixing the conductors of the power supply cord inside the lamp holder. Such clamping means is used in any case also in other kinds of lamps simply to achieve greater safety, for example to prevent any accidental impacts affecting the electrical cord from altering its connection to the terminals located in the lamp holder. This clamping means is usually constituted by wings that can flex elastically toward or away from the axis of the passage through which the power supply cord passes, are formed monolithically with the cap and protrude toward the lamp holder body. Such wings are designed to engage, when the cap and the lamp holder body are coupled, inside appropriately provided seats or guides provided in the lamp holder body, so that as a consequence of the axial movement of the cap with respect to the lamp holder body the wings flex toward the axis of the passage for the electrical power supply cord. The wings have, in an intermediate region of their extension, at least one tooth that protrudes inside the passage for the electrical power supply cord, and the mutual coupling of the cap and the lamp holder body produces a flexing of the wings that causes the tooth to move toward the axis of the passage, automatically clamping the cord. Although these lamp holder types ensure excellent clamping of the power supply cord, which is performed automatically when the cap is assembled to the lamp holder body, they have the drawback of requiring a particular execution of the lamp holder body in order to obtain the guides or seats designed to be engaged by the wings of the clamping means in order to achieve the intended clamping of the wings on the electrical power supply cord. The provision of these seats or guides increases the complexity of the production of the lamp holder body and inevitably increases its production costs. An example of such lamp holder type is disclosed in EP-A-0929132 and is also defined in the preamble of claim 1. The aim of the present invention is to obviate the above noted drawback by providing a lamp holder with quick locking of the electric power supply cord without requiring, in the lamp holder body, the provision of particular seats or guides for activating the cord clamping means. Within this aim, an object of the invention is to provide a lamp holder in which the means used to clamp the electrical power supply cord is limited substantially to the cap alone. Another object of the invention is to provide a lamp holder in which clamping of the electrical power supply cord is in any case achieved automatically when the cap is assembled with the lamp holder body. Another object of the invention is to provide a lamp holder that can be manufactured at competitive costs. This aim and these and other objects that will become better apparent hereinafter are achieved by a lamp holder with quick locking of the electric power supply cord, as defined in claim 1. Further characteristics and advantages of the invention will become better apparent from the detailed description of a lamp holder according to the invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein: Figure 1 is a perspective view of the cap of the lamp holder according to the invention; Figure 2 is a perspective view of the cap of the lamp holder according to the invention, taken from a different angle with respect to Figure 1; Figure 3 is an axial sectional perspective view of the cap of the lamp holder according to the invention; Figure 4 is an axial sectional view of the cap of the lamp holder according to the invention; Figure 5 is an exploded axial sectional view of the lamp holder according to the invention; Figure 6 is an axial sectional view of the lamp holder according to the invention in the assembled condition; Figure 7 is an enlarged-scale sectional view of Figure 6, taken along the line VII-VII. With reference to the figures, the lamp holder according to the invention, generally designated by the reference numeral 1, is composed in a per se known manner of a lamp holder body 2 and of a cap 3 that is detachably associated with the lamp holder body 2. The lamp holder body 2 is preferably substantially cylindrical and has, starting from one of its axial ends, a seat 4 that is designed to receive the lamp. The seat 4 can have, in a per se known manner, a thread 5, as shown, or bayonet-type coupling means, depending on the type of lamp that it is to be received. The lamp holder body 2 has, proximate to its end that can engage the cap 3, a cavity 7 that is open toward the cap 3 and accommodates internally, in a central region, a block 8 which contains, in a per se known manner, the electric terminals 9 for fixing the conductors that compose the electrical power supply cord 10. The block 8 is connected to the side walls that delimit the cavities 7 by bridges 8a. In the illustrated lamp holder there are two bridges 8a located in two diametrically opposite regions of the lamp holder body 2. The electrical terminals 9 can be constituted by screw-down terminals or elastic terminals, according to the requirements. The cap 3 also is preferably substantially cylindrical or shaped like a dome with a circular base and is crossed centrally by a passage 11 for the electrical power supply cord 10. More particularly, the passage 11 is formed by a portion 12 that is shaped like a hollow cylinder and lies coaxially around the axis of the cap 3. The cap 3 has means for clamping the cord 10 that can be activated when the cap 3 is assembled with the lamp holder body 2. Preferably, the cap 3 is assembled with the lamp holder body 2 through snap-acting mutual coupling means. More particularly, the cap 3 has, in two diametrically mutually opposite regions, two tabs 13 that protrude toward the lamp holder body 2. The tabs 13 are each provided with a tooth 14 that forms an axial shoulder 14a. The tabs 13 can flex elastically away from the axis of the cap 3 in order to allow the axial shoulders 14a, formed by the teeth 14, to move past corresponding axial shoulders provided, in a per se known manner, on the side wall of the lamp holder body 2 and then, by elastic reaction of said tabs 13, to engage by way of the shoulders 14a the corresponding axial shoulders provided on the side wall of the lamp holder body 2. The cord clamping means comprises at least one wing 20 that is connected, at one of its ends, to the portion 12 of the cap 3 in which the passage 11 is formed. Said wing 20 protrudes with its opposite end 21 toward the lamp holder body 2. The wing 20 has, in an intermediate region of its extension, a tooth 22 that protrudes toward the axis of the passage 11. The wing 20, when the cap 3 is assembled with the lamp holder body 2, engages by means of its end 21 against the side wall of the cavity 7, so as to achieve an elastic flexing of the wing 20 that moves the tooth 22 toward the axis of the passage 11 in order to perform the axial locking of the cord 10 inside the passage 11. Preferably, the end 21 of the wing 20, when the cap 3 is assembled with the lamp holder body 2, enters the region of the cavity 7 that is comprised between the side wall of the cavity 7 and the block 8 that supports the electrical terminals 9. The end 21 of the wing 20 is shaped like a plane 21a that is inclined with respect to the axis of the cap 3 and of the lamp holder body 2 so that the coupling between the cap 3 and the lamp holder body 2, provided through a relative axial movement between the cap 3 and the lamp holder body 2, produces a gradual elastic flexing of the wing 20 toward the axis of the passage 11. Preferably, the end 21 of the wing is bifurcated so as to enter, with its two arms 23a and 23b, two regions 7a and 7b of the cavity 7 that are located between the side wall of the cavity 7 and the block 8 and are separated by the bridge 8a that connects the side wall of the cavity 7 to the block 8. The portion of the wing 20 that is connected to the cap 3 is provided as a part of the hollow cylindrical portion 12 and is separated from the remaining part of the portion 12 by axial slots, so that the wing 20 can flex elastically toward and away from the axis of the passage 11. The tooth 22 is preferably inclined, with respect to the axis of the passage 11, in the same direction in which the cord 10 is inserted in the passage 11. In this manner, the engagement of the tooth 22 with the cord 10 produces a highly secure clamping of the cord 10, since the tooth 22 jams against the cord 10, and any traction on the cord 10 aimed at extracting the cord 10 from the lamp holder increases the extent of this jamming. Preferably, the end of the tooth 22 that is directed toward the axis of the passage 11 is toothed so as to further increase the grip of the tooth 22 on the body 10. Preferably, there are two wings 20 that are arranged in two regions that are diametrically mutually opposite with respect to the passage 11, so that the cord clamping action is applied to two diametrically mutually opposite regions of the cord 10. Conveniently, the portion 12 with the wings 20 is formed monolithically with the remaining part of the cap 3. The outer side wall of the portion 12 can be threaded in order to be used as an element for fixing the lamp holder to a supporting element. The outer side wall of the lamp holder body 2 also can be threaded or smooth according to the requirements. The operation of the lamp holder in performing the clamping of the cord 10 is as follows. While the cap 3 is disengaged from the supporting body 2, the electrical power supply cord 10 is inserted through the passage 11 and the conductors that constitute the cord 10 are fixed to the terminals 9. Before assembling the cap 3 to the lamp holder body 2, by pulling the cord 10 any excess cord is reduced, and the cord exits toward the lamp holder body 2 so that it is possible to easily assemble the cap 3 with the lamp holder body 2. Then the cap 3 is assembled to the lamp holder body 2, preferably with a snap-acting coupling system, as already described, by moving axially the cap 3 with respect to the lamp holder body 2. When the cap 3 couples to the lamp holder body 2, the wings 20 engage, with their end 21 shaped like an inclined plane 21a, against the side wall of the cavity 7. This engagement produces an elastic flexing of the wings 20 toward each other and toward the axis of the passage 11 and makes the teeth 22 engage against the cord 10, locking it axially. It should be noted that since the wings 20 directly engage the side wall that delimits the cavity 7, i.e., a wall that is also present in the bodies of lamp holders of the conventional type, no particular shape of the lamp holder body is required in order to produce the elastic flexing of the wings 20 that locks the cord 10. In practice it has been found that the lamp holder according to the invention fully achieves the intended aim, since the means for automatically clamping the cord during the coupling between the cap and the lamp holder body requires no particular modifications of the lamp holder body, which therefore can be constituted by a lamp holder body of the standardized type or in any case of a type that is already available. In practice, the materials used, as well as the dimensions, may be any according to requirements and to the state of the art. 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.

Claims: A lamp holder (1) with quick locking of the electric power supply cord (10), comprising a lamp holder body (2) in which there is, starting from one of its ends, a seat (4) that can be engaged by a lamp and a cap (3) that is associable with the opposite end of said lamp holder body (2); a passage (11) for the electrical power supply cord (10) being formed in said cap (3); said lamp holder body (2) having, proximate to its end that can engage said cap (3); a cavity (7) that is open toward said cap (3) and supports, in a central region, a block (8) that carries the electrical terminals (9) for fixing said cord (10); said cap (3) being provided with cord clamping means that can be activated by the assembly of said cap (3) with said lamp holder body (2); said cord clamping means comprises at least one wing (20) that is connected, at one of its ends, to the portion (12) of said cap (3) in which said passage (11) is provided, its opposite end (21) protruding toward said lamp holder body (2); said wing (20) having, in an intermediate region of its extension, a tooth (22) that protrudes toward the axis of said passage; characterized in that said wing (20) is arranged in a position so that, upon assembly of said cap (3) with said lamp holder body (2) engages by means of said opposite end thereof against the side wall of said cavity (7) that is comprised between the side wall of the cavity (7) and the block (8) for an elastic flexing of said wing (20) that makes said tooth (22) move toward the axis of said passage in order to axially lock said cord (10) in said passage (11). The lamp holder according to claim 1, characterized in that said opposite end (21) of the wing, upon assembly of said cap (3) with said lamp holder body (2), enters the region of said cavity (7) that lies between the side wall of said cavity and said block (8) that carries the electrical terminals (9). The lamp holder according to claims 1 and 2, characterized in that said opposite end (21) of the wing (20) is shaped so as to form a plane (21a) that is inclined with respect to the axis along which said cap (3) is coupled to said lamp holder body (2). The lamp holder according to one or more of the preceding claims, characterized in that said opposite end (21) of the wing (20) is bifurcated so that its two arms (23a, 23b) enter two regions (7a, 7b) located between the side wall of said cavity (7) and said block (8) that supports the electrical terminals (9), said regions being separated by a bridge (8a) for connecting said block (8) to said side wall. The lamp holder according to one or more of the preceding claims, characterized in that said portion (12) of the cap (3) in which said passage (11) is formed is shaped like a hollow cylinder, and in that a portion of said wing (20), starting from said end, constitutes a part of said hollow cylinder. The lamp holder according to one or more of the preceding claims, characterized in that said tooth (22) protrudes in a direction that is inclined, with respect to the axis of said passage (11), in the same direction in which said cord (10) is inserted in said passage (11). The lamp holder according to one or more of the preceding claims, characterized in that the end of said tooth (22) that is directed toward the axis of said passage (11) is toothed. The lamp holder according to one or more of the preceding claims, characterized in that said wing (20) is formed monolithically with said cap (3). The lamp holder according to one or more of the preceding claims, characterized in that said at least one wing (20) comprises two wings (20) which are arranged in two regions that are diametrically opposed with respect to said passage (11). The lamp holder according to one or more of the preceding claims, characterized in that the outer side wall of said hollow cylindrical portion (12) provided with said passage (11) is threaded. The lamp holder according to one or more of the preceding claims, characterized in that said cap (3) is associable with said lamp holder body (2) by way of means for snap-acting mutual coupling through a relative movement substantially parallel to the axis of said passage (11).

Inventors: GERVASONI DOMENICO, GERVASONI, DOMENICO
Applicants: ARDITI SPA, ARDITI S.P.A.
Application year: 2001
Main classification: F21V27
IPC codes: H01R33, F21V27, H01R13