WO2019091985A1

WO2019091985A1 - Push-on socket

Info

Publication number: WO2019091985A1
Application number: PCT/EP2018/080368
Authority: WO
Inventors: Jose Manuel MARTINEZ GONZALEZ; Julien LAMO; Ren RENBIN
Original assignee: H.B.F.
Priority date: 2017-11-07
Filing date: 2018-11-06
Publication date: 2019-05-16
Also published as: CN207559185U; RU2020112864A3; PL3707783T3; EP3707783B1; ES2923112T3; RU2020112864A; EP3707783A1

Abstract

An electrical socket (1) comprising: - a base (8) comprising terminals (10) configured to be connecting to mains, - a casing (6) mounted on said base (8) and comprising an inner tubular wall (63) extending along an axis of engagement (A) oriented towards said base (8), - a movable plate (4) coupled to said inner tubular wall (63) of the casing (6) and configured to translate along said axis of engagement (A) between a waiting position and a locking position, and vice versa, - at least one locking system (9) coupled to said base (8) and extending/oriented perpendicular to said axis of engagement (A), and, when the movable plate (4) is pressed towards the base (8) said at least one locking system (9) fixes the movable plate (4) in the locking position, and when the movable plate (4) is pressed again towards the base (8), said movable plate (4) releases itself and the movable plate (4) moves upwards to return to the waiting position.

Description

Push-on socket

1. Technical field

The present invention relates to an electrical socket for connecting a power source to an electrical / electronic apparatus.

2. Background art

The existing European sockets are used with plugs to transmit current to their appliances. In order to do so, the plug part must be placed inside the socket and plug pins in reliable contact with socket connecting terminals.

The plug is retained within the socket through the clipping effort done by terminals on pin parts. In order to decouple it from socket a pulling force of certain degree must be applied (depending on the tolerance of the plug pins and socket terminals as well as plug and socket housing eventual friction).

An excessive pulling effort may damage the socket or its enclosure fixing parts. A non- sufficient pulling effort by elder or handicapped user may be ineffective for this purpose.

There are various known solutions to optimize the effort to be applied to the plug to remove it from the socket.

For example, it is known from document EP 2 385 588 an electrical safety plug which comprises a housing having an upper part and an inner lower part in which connection terminals are fixed, a lifting plate coupled to an inner part of the housing and moving vertically.

The lifting plate comprises at least one insertion hole in which a connector pin of a connector is inserted to connect to the connection terminals. A pressure on the plug pins on shutter system will move the movable plate inside the socket and reaching an engagement position, the shutter flaps will turn allowing the plug pins to couple the socket terminals. At same time, the lift operation unit performs a vertical press operation to lock the movable plate at that engagement position.

When the lifting plate is pressed inwards by plug, the lifting plate is released by lift operation unit and moved upward to space the terminal pin of the connector terminal connector and "release" the connector.

In fact, once the plug is coupled to the electrical socket, it is necessary to make an inward pressure to decouple it. Extraction of the plug by force is always possible and this causes the sliding wall to return to the standby position.

The disadvantage of this solution is that the movement of lift plate inside the socket only happens when the plug pins exerts a continuous effort on shutter part (instead of spreading the effort on whole plate surface) until plug surface touches lift plate.

Therefore, the push effort for forcing the plug pins must be straight and perpendicular to the shutter to be effective which is not always possible when socket is located in inconvenient places. An inadequate effort might also damage the shutter or not be effective for plug coupling.

Furthermore, the removal of the plug (by force or pressure inwards) will return the lift plate to the waiting position, replicating the potential inconveniences depicted in previous paragraph.

The lift operation unit, responsible of locking and unlocking the plate, will only work when the plug pins are inserted and contact an element (pressing protrusion) of the lift operation unit.

That lift operation unit relies on vertical movement of that unit for its operation as well as continuous contact with central bar of lifts plate. The disadvantage of this solution is that is not possible to stand the European standards which request at least 10,000 cycles for safety shutter opening and closing. A premature ageing of those parts will eventually happen with a single (vertical) locking/unlocking system.

Also known from document EP 2 555 336 is a socket comprising a casing housing at least two connection terminals, a trim mounted at the front of the casing and having two access openings at said connection terminals, and a rear shutter having two wings. This rear shutter, secured to the housing, is movable between a closed position in which its wings prohibit access to said connection terminals and an open position in which they allow this access.

Although this construction promotes safety, it does not retain additional functions of ease of insertion because the double shutter system increases the difficulty for the elderly or handicapped users and no longer extraction because it lacks an ejector system.

Document EP 2 456 024 also discloses an electrical socket comprising:

- a cylindrical wall delimiting a well,

- a flap closing the cross-section of this well, movable in translation with respect to said cylindrical wall, comprising at least two orifices, - a central pillar adapted to slide axially in a groove to translate together with the flap,

- a shutter mounted at one end of the central post adapted to pivot between a position for closing off said orifices of the shutter and a position for opening said orifices,

Remarkably, the shutter is free to pivot with respect to said central post between its open and closed positions.

This system improves the previous EP 2 555 336 by returning the cylindrical wall to its waiting position without taking into account the position of the flap (depressed or not). As soon as the pins are no longer in contact with the active parts, the cylindrical wall slides upwards (waiting position).

On the other hand, the extraction and insertion are not facilitated with this solution, having the same problems as those identified in the document EP 2 555 336.

Thus, conventional electrical sockets, which aim to optimize the effort to be applied to the plug to remove it from the socket, present a complex, and thus expensive, structure.

Moreover, no conventional electrical socket, for connecting a power source to an electrical / electronic apparatus, allows to uncouple, easily, the plug with simple pressure on the surface plate while keeping all the necessary features from a secure plug.

3. Technical solution

An object of the present disclosure is to alleviate the drawbacks and insufficiencies resulting from the above-mentioned prior art.

To this purpose, the present disclosure relates to an electrical socket comprising:

- a base comprising terminals configured to be connecting to mains,

- a casing mounted on said base and comprising an inner tubular wall extending along an axis of engagement oriented towards the base,

- a movable plate coupled to the inner tubular wall of the casing and configured to translate along the axis of engagement between a waiting position and a locking position, and vice versa,

- at least one locking system coupled to the base and extending perpendicular to the axis of engagement,

and, when the movable plate is pressed towards the base said at least one locking system fixes the movable plate in the locking position, and

when the movable plate is pressed again towards the base, the movable plate releases itself and the movable plate moves upwards to return to the waiting position. Hence, the extraction of a plug plugged into a socket according to the present disclosure is facilitated. In fact, the extraction force required to unplug the plug is reduced.

According to an aspect, said at least one locking system comprises:

- a housing disposed in an inner part of the base and extending perpendicular to the axis of engagement,

- a bar disposed inside the housing and extending perpendicular to the axis of engagement,

- a stopper moving along the bar,

- two asymmetrical springs configured to place the stopper in a not centered position on the bar.

Such a configuration of locking system provides a locking/unlocking solution that is simple, effective, robust/durable and space saving. Moreover, the manufacturing costs of such a locking system are low.

According to another aspect, when the movable plate moves up to the position where the stopper is located, the stopper is configured to exert a pressure on an inner portion of the movable plate to fixe the movable plate in the locking position.

According to another aspect, the stopper and the two asymmetrical springs are coaxially mounted on the bar, and wherein the stopper is disposed between the two asymmetrical springs.

Such asymmetrical springs are a simple and effective solution to offset the stopper at a lower cost.

According to another aspect, the movable plate comprises:

- an outer surface with at least two orifices,

- a pair of legs configured to slide into the socket along the axis of engagement and configured to interact with said at least one locking system,

- two main springs oriented along the axis of engagement so that the springs help the movable plate to return to the waiting position,

and, when the movable plate is blocked at locking position, a pressure on the outer surface towards the base allows the movable plate to release itself and the movable plate returns to the waiting position.

Such a configuration makes it easy and cost-effective to return the movable plate to the waiting position.

According to another aspect, each leg is configured to slide into a first groove formed in the inner tubular wall of the casing and into a second groove formed in the base.

Such a configuration makes it easy and cost-effective to guide the movable plate.

According to another aspect, each leg comprises an inner groove and an upper groove, the inner and upper grooves are configured to interact with said at least one locking system.

Such a configuration makes it possible to simplify, at a lower cost, the structure of the locking system by placing certain elements of the locking system directly on the guide elements.

According to another aspect, each leg is configured to interact with one locking system.

The implementation of two (or more) locking systems improves the effectiveness of the locking system. Such configuration also improves life of the locking system, and therefore the life of the socket.

According to another aspect, the inner and upper grooves are configured to interact with the stopper.

According to another aspect, for each leg, the inner groove is configured to:

- displace the stopper along the bar when the movable plate is pressed towards the base , and

- retain the stopper when the movable plate reaches the locking position.

According to another aspect, the movable plate comprises a safety shutter.

Such a shutter improves user(s) safety.

According to another aspect, the electrical socket further comprises means for fixing the base to a desktop.

Such a configuration makes it easier to fix a socket according to the present disclosure onto a desk.

The present disclosure also relates to a multiple extension lead comprising a plurality of electrical sockets as previously described.

Such a configuration makes it possible to connect a plurality of plugs into sockets according to the present disclosure.

In other words, the present disclosure relates to a socket in which the extraction means comprise, on the one hand, elastic thrust elements and doubled coupling and decoupling elements that are mobile by parallel and perpendicular translation to the socket.

The movable plate can move in translation without the need for an electrical plug, just by means of a pressure on its surface. When said movable plate arrives at the locking position, its contacting surface slides into the base grooves where stoppers of double locking system will contact and block the inner grooves of sliding surfaces.

The inwards pressure of the movable plate releases itself from stoppers displacing them along their bars. The return of the said movable plate to the waiting position can be carried out with a slight pressure on the plated towards the inside of the socket.

The locking system perpendicular to the axis of engagement blocks the movable plate when matching the upper area of inner groove. It does not touch the connecting terminals neither interacts the safety shutter.

A vertical movement (inwards) of the movable plate allows itself to be released, pushed up by the springs and move along the axis of engagement till arriving the upper ending of the casing groove.

The two independent elements (movable plate and locking system) make a reliable solution for enduring a high number of function cycles.

Once the movable plate can be locked with a pressure on its whole surface, it is easy to plug no matter the emplacement or the user ability. As explained, the movable plate will only unlocks itself from stoppers if a pressure inwards is exerted.

In case of forcible unplug, the movable plate will remain at locking position as it does not depend on the physical contact with plug pins to remain in that position. Therefore, it will be ready for a new plug to couple directly with connecting terminals and safety is ensured by shutter system on movable plate.

Due to such configuration, it is especially suitable for plugging sockets combining performance and comfort: for instance those sockets for technical environment (such as kitchen, office) as depicted in further paragraphs where accessibility to power source is limited.

Furthermore, since there are two independent elements working in perpendicular directions and not in contact with safety shutter or plug pins the solution becomes sustainable in time and able to endure a long number of cycles as European Standard standards. Furthermore, the two systems are not in contact except when the movable plate reaches the surface of the locking system preventing its damaging for continuous use.

Departed extension leads are also especially suitable for elder and handicapped user providing an ergonomic and reachable solution for their needs. 4. Brief description of the drawings

The invention can be better understood with reference to the following description and drawings, given by way of example and not limiting the scope of protection, and in which:

- figure 1 is a perspective view illustrating an electrical socket with its front plate in the waiting position;

- figure 2 is an exploded view of an electrical socket conforming to this solution;

- figure 3 is a rear perspective view illustrating the connection elements of the electrical socket to mains;

- figure 4 is a front perspective view of the movable plate: outer surface, shutter and housing to move inwardly of the electrical socket;

- figure 5 is an exploded view of movable plate according to this solution;

- figure 6 is a rear exploded view of this movable plate according to this solution;

- figure 7 is a frontal rear view of the middle part and connecting terminals;

- figure 8 is a front view of the base and locking system;

- figure 9 is a exploded view of locking system according to this solution;

- figure 10 is a rear exploded view of an electrical outlet conforming to this solution;

- figure 11 is a view of the electrical socket in the waiting position;

- figures 12A and 12B are views of the electrical socket descending inside the socket before reaching the locking position;

- figures 13A and 13B are respectively a view of the electrical socket descending inside the socket arriving the locking position and a view of the electrical socket reaching the bottom position;

- figures 14A and 14B are respectively a view of the electrical socket ascending inside the socket and a view of the electrical socket arriving the locking position and being blocked;

- figures 15A and 15B are respectively a view of the electrical socket descending inside the socket and, once released itself, a view of the electrical socket ascending inside the socket;

- figures 16A and 16B are respectively a view of the electrical socket ascending inside the socket and a view of the electrical socket towards the waiting position;

- figure 17 is a perspective view illustrating a second embodiment of the present invention (a socket for the German standard) with its front plate in the waiting position;

- figure 18 is a front exploded view of the electrical socket according to the second embodiment of the present invention; - figure 19 is a rear exploded view of the electrical socket according to the second embodiment of the present invention;

- figure 20 is a perspective view of the electrical socket according to a third embodiment of the present invention once installed on a desktop;

- figure 21 is a schematic structural view of a socket according to the third embodiment of the present invention integrated on a desktop; and

- figure 22 is a schematic illustration of an alternative configuration that is particularly suitable for elderly and disabled users. 5. Detailed description

The present invention relates to a system to help uncouple the plug with simple pressure on the surface plate while keeping all the necessary features from a secure plug.

Figure 1 shows an electrical wall socket (1) designed to receive a complementary electrical plug for the connection of this plug to mains. This product is fixed to recessed box typically through screws to be tightened through the orifices (65) on frame support (61).

As shown in figure 2, the various internal elements of the electrical socket (1) are housed in a casing (6). This casing (6) is made of insulating material, for example by molding a plastic material.

Figure 3 shows the system for connecting this electrical socket (1) to the mains. This is done on backside of the base (8) through terminal holes (83) secured by screws. As soon as the wire plugs into, the tightening of the screws (81) will secure the wires inside the base (8) ensuring the contact of wires with connecting terminals (10).

This solution is compatible with the Franco-Belgian standard. As illustrated on figure 2, the location of the main springs (7) as well as the tubular legs (48) as well as the movable plate (4) and the two locking systems (9) respect the dimensional constraints of this normative. A solution compatible with the German standard is also cited as a reference.

Figure 4 shows the movable plate (4) of the electrical socket (1), which can be displaced, in translation from a waiting position along the axis of engagement (A) (figure 2), to a locking position, and vice versa.

As soon as an inwards pressure on the movable plate (4) is made, the movable plate

(4) will translate along the axis A as shown in figure 10. The movement in translation along the axis of engagement (A) of the movable plate (4) of figure 10 is guided by the tubular legs (48) and two first grooves (64) formed in the casing (6) and two second grooves (84) formed in the base (8).

As illustrated on figure 9, each locking system (9) comprises a stopper (93) located in a side of a metallic bar (92) due to the length of a larger spring (91), named first spring (91). The smallest spring mounted on the metallic bar (92) is named second spring (95).

During the movement of translation of the movable plate (4), the inner grooves (47) of the rectangular legs (45) will displace the stopper (93) from its resting position but they will not be captured by the stopper (93) except at locking position.

Figures 2 and 4 show the movable plate (4) for sliding in translation along the axis of engagement (A) by the inner tubular wall (63) of the casing (6) from the waiting position (I) towards the inside of the base with a multiple guiding system:

- the two rectangular legs (45) of the movable plate (4) sliding into first grooves (64) made for this purpose in the cylindrical wall (63) of the casing (6),

- the two tubular legs (48) of the first housing (44) supported by the main springs (7) interdependent and integral with the support base (8).

Throughout this translation, the rectangular legs (45) traverse a downward first grooves (64) inside the casing (6) arriving at the second grooves (84) of the base (8) parallel to the axis A.

Figure 5 and figure 6 show an exploded view of this movable plate (4). The movable plate (4) comprises:

- an outer surface (41) coupled to the first housing (44) by three clips (46),

- a small spring (42) that makes returns,

- a safety shutter (43) located between the outer surface (41) and the first housing (44) bearing in the two elements for its pivoting,

- the two rectangular legs (45) with the inner grooves (47),

- the two tubular legs (48) where the main springs (7) are housed.

In this embodiment, the inner tubular wall (63) is substantially cylindrical.

As shown in figure 6, the safety shutter (43) is housed between the outer surface (41) and the first housing (44) and uses the two elements for its operation. A detail of rectangular legs (45) and their inner grooves (47) is also displayed in that view.

In figure 7, it is shown the middle part (5) that is fixed to base (8) by four bottom screws. That middle part (5) holds the connecting terminals (10) avoiding any unintended access out of surface cleared by safety shutter (43). The plastic wall (51) separates the connecting terminals (10) from the area (52) where the locking system (9) is placed avoiding any interaction between them.

In figure 8, it is shown the base (8) where the two locking systems (9) are located as well as the round tubes (82) for placing the main springs (7).

Figure 9 shows all the elements of each locking system (9). Each locking system (9) comprises:

- a second housing (94) placed on the base (8)

- a metallic bar (92) where the stopper (93) slides

- a first spring (91) and a second spring (95) connected to

- a stopper (93) typically made in metal.

The stopper (93) is able to move in the surface perpendicular to the axis A when touched by inner grooves (47) of movable plate (4) and it will try to return to the resting position determined by the elasticity of the first springs (91) and the second springs (95).

In figure 10, it is shown the various elements of the electrical socket (1) from a rear view for better interpretation.

In figure 11, it is shown the different elements combined in waiting position (I) and main springs (7) are in released position. As displayed, the movable plate (4) is in the most external position of the socket. The stoppers (93) of locking systems (9) are in their resting position and not interacted by inner grooves (47) of rectangular legs (45).

In figures 12A and 12B, it is shown the translation of the movable plate (4) along the inner cylindrical wall (63) of casing (6). At some point, the lower ending (47') of the inner grooves (47) will touch (figure 12A) and displace (figure 12B) the stoppers (93) from its resting position compressing the first spring (91) and extending the second spring (95).

In figures 13A and 13B, it is shown the arrival to bottom of the movable plate (4) along the cylindrical wall (63) of casing (6). The movable plate (4) keeps descending (figure 13A) and displacing the stoppers (93) from resting position to its furthest position on the right.

The rectangular legs (45) arrive to bottom (figure 13B) of second grooves (84) of the base (8). At that position, the stopper (93) makes partially its way back to resting position and faces the right salient of upper groove (49).

At same time, the two main springs (7) are at their maximum compressing position and will start to push the movable plate (4) up. In figures 14A and 14B, it is shown how the movable plate (4) starts its return trip towards outside pushed by the two main springs (7). Each stopper (93) pushed by the first spring (91) will move to left direction while the plate moves up (figure 14A).

As shown on figure 14B, each stopper (93) will face the left salient of the inner groove (47) as well as its lower part blocking its leg to keep moving it up. The stoppers (93) pushed and pulled by the first and second springs (91, 95) respectively of its locking system (9) are exerting pressure on the left salient of inner groove (47). The stopper (93) can only move along the longitudinal axis defined by the metallic bar (92) and tends to come back to its resting position on left area. Each locking system (9) blocks one of the rectangular legs (45) of movable plate (4). A locking system (9) is associated with a rectangular leg (45).

That locking position matches the optimal emplacement of the movable plate (4) for ensuring a reliable connection with terminals (10) if a plug is coupled to.

In figures 15A and 15B, it is explained how the movable plate (4) releases itself from the locking systems (9). Each rectangular leg (45) is being blocked by stoppers (93) retaining the inner grooves (47) to slide up (figure 15A).

A pressure on outer surface (41) of the movable plate (4) towards inside the socket base (8) will push the rectangular legs (45) slightly down. The left salient of inner groove (47), of each rectangular leg (45), will not be in contact with the stopper (93) anymore, as shown on figure 15B. The stopper (93) is pushed to the left by the combined effort of its two first and second springs (91, 95). That movement is independent from the movable plate (4) and linked to the internal construction of the locking systems (9).

In figures 16A and 16B, it is shown how the movable plate (4) and the stopper (93) follow their independent path vertically and horizontally respectively. The stopper (93) will returns (figure 16A) to resting position while the movable plate (4) is being pushed up by the main springs (7) until returns to waiting position (I) as shown on figure 16B.

As previously stressed, the movable plate (4) and locking systems (9) are independent elements that interact for ensuring an optimal position of movable plate (4) and guaranteeing a reliable contact of terminals (10) with plug pins.

The locking systems (9) will be in charge of blocking the movable plate (4) at the position above mentioned when movable plate (4) is returning from bottom position.

The movable plate (4) will release itself from the locking systems (9) when a pressure inwards on the movable plate (4) is exerted. Those two locking systems (9) remain independent except for the minimum interact for ensuring a locking position at the desired emplacement.

Figure 17 shows an equivalent solution for the German standard, the elements used for its realization are those of the Franco-Belgian version with the dimensional and shape differences of the electrical plug for Germany.

As shown on figure 18, the shape of the movable plate (4) and the first housing (44) is indeed different as well as the location of the small spring (42) of the safety shutter (43). Also the distance between the plate (4) and the connecting terminals (10) follows the German standard although these differences do not bring substantial changes to the technical solution chosen.

Figure 19 shows the rear view of the elements to show that the changes made are only those indicated previously.

Figure 20 shows a solution specially conceived for desktop or kitchen table. Since most of this furniture is provided with pre-cut holes of 60mm for cable management, an extension lead that takes advantage of these features as well as remains flat are embedded into desktop.

As displayed, the base (8) of the extension lead will pass through the hole pre-cut on desktop (11) and fixed by a threaded part (12). The casing (6) will be retained outside the desktop (11) and the outer surface (41) of movable plate will remain flat with table when not displaced inwards.

Figure 21 shows the product ready to use in an optimal display blending in the desktop at its waiting position.

Figure 22 shows an alternative construction especially suitable for elder and handicapped. Since most of wall sockets are located at minimum height from floor, it is not convenient for them plugging and unplugging appliances.

A multiple extension lead fixed to wall and providing several socket outlets with this technical solution will solve the double problem of reaching and extracting the plug when used.

It shares the same movable plate (4) and base (8) and locking systems (9) but the construction of the casing (6) is larger to support several outlets as well as the decorative plate (2).

In addition a duct tube (21) houses the extension cord which plug (22) will be connected to the existing wall socket. The present invention is in no way limited to the shape of the socket or its connection to the mains; it is indeed possible to envisage changes in the size or shape or a connection system using screw terminals. The electrical socket is here adapted to be housed in a box embedded or protruding on any wall. In a variant, it may be an electrical socket of the extension type, a multiple socket.

The present invention can also be adapted to any type of electrical plug adapter, for example an extension cord, a reel or a wall adapter as well as to add other functions to this solution via an independent electronic board.

Claims

An electrical socket (1) comprising:

- a base (8) comprising terminals (10) configured to be connecting to mains,

- a casing (6) mounted on said base (8) and comprising an inner tubular wall (63) extending along an axis of engagement (A) oriented towards said base (8),

- a movable plate (4) coupled to said inner tubular wall (63) of the casing (6) and configured to translate along said axis of engagement (A) between a waiting position and a locking position, and vice versa,

- at least one locking system (9) coupled to said base (8) and extending perpendicular to said axis of engagement (A),

and, when the movable plate (4) is pressed towards the base (8) said at least one locking system (9) fixes the movable plate (4) in the locking position, and

when the movable plate (4) is pressed again towards the base (8), said movable plate

(4) releases itself and the movable plate (4) moves upwards to return to the waiting position.

The electrical socket (1) of claim 1, wherein said at least one locking system (9) comprises:

- a housing (94) disposed in an inner part of said base (8) and extending perpendicular to said axis of engagement (A),

- a bar (92) disposed inside said housing (94) and extending perpendicular to said axis of engagement (A),

- a stopper (93) moving along said bar (92),

- two asymmetrical springs (91, 95) configured to place the stopper (93) in a not centered position on said bar (92).

The electrical socket (1) of claim 2, wherein, when the movable plate (4) moves up to the position where the stopper (93) is located, the stopper (93) is configured to exert a pressure on an inner portion of the movable plate (4) to fixe the movable plate (4) in the locking position.

The electrical socket (1) of claim 2, wherein said stopper (93) and said two asymmetrical springs (91, 95) are coaxially mounted on the bar (92), and wherein said stopper (93) is disposed between said two asymmetrical springs (91, 95).

The electrical socket (1) of claim 1, wherein the movable plate (4) comprises: - an outer surface (41) with at least two orifices,

- a pair of legs (45) configured to slide into the socket along the axis of engagement (A) and configured to interact with said at least one locking system (9),

- two main springs (7) oriented along the axis of engagement (A) so that said springs (7) help the movable plate (4) to return to the waiting position,

and, when the movable plate (4) is blocked at locking position, a pressure on the outer surface (41) towards the base (8) allows the movable plate (4) to release itself and the movable plate (4) returns to the waiting position.

The electrical socket (1) of claim 5, wherein each leg (45) is configured to slide into a first groove (64) formed in said inner tubular wall (63) of the casing (6) and into a second groove (84) formed in said base (8).

The electrical socket (1) of claim 5, wherein each leg (45) comprises an inner groove (47) and an upper groove (49), said grooves (47, 49) are configured to interact with said at least one locking system (9).

The electrical socket (1) of claims 5, wherein each leg (45) is configured to interact with one locking system (9).

The electrical socket (1) of claims 2 and 7, wherein said grooves (47, 49) are configured to interact with said stopper (93).

The electrical socket (1) of claim 9, wherein, for each leg (45), said inner groove (47) is configured to:

- displace said stopper (93) along said bar (92) when the movable plate (4) is pressed towards the base (8), and

- retain said stopper (93) when the movable plate (4) reaches the locking position. The electrical socket (1) of claim 1, wherein said movable plate (4) comprises a safety shutter (43).

The electrical socket (1) of claim 1, further comprising means for fixing said base (8) to a desktop (11).

A multiple extension lead comprising a plurality of electrical sockets of claim 1 to 11.