DE69200988T2 - Two-part adapter for connecting an electrical device with a plug to a wall socket. - Google Patents

Description

The present invention relates generally to the connection of any electrical device to a wall socket.

As you know, this is done by inserting the plug, which is usually provided on the power cable of the electrical device, into the socket.

This obviously presupposes an appropriate correspondence between this plug and the socket.

However, this correspondence may fail due to different standards when used in certain countries.

It is therefore necessary to use an intermediate adapter, i.e. an additional connection part which, on the one hand, comprises a socket part suitable for receiving the plug of the electrical device and, on the other hand, a plug part suitable for plugging into the wall socket.

Currently, this socket part and this plug part are formed as one piece and the whole is made from a single mold.

Furthermore, the electrical contact means that such a unit has correspond to unchangeable standard configurations.

Taking into account the number of different standards to be taken into account and the different combinations of these to be provided, a relatively large number of different adapters must be provided in order to cover all the possibilities to be considered, in the order of about 17 or 18.

Alternatively, an adapter has already been proposed that can adapt itself to various standards, if not all of them.

However, this requires influencing the electrical connection devices in order to arrange them accordingly.

At least some of these electrical contact means are therefore adjustable in terms of position.

This results in a certain degree of complexity in use and a certain degree of uncertainty regarding the quality of the associated electrical contacts inside, to the detriment of safety.

The subject of the present invention is, in general, a device which makes it possible to avoid these disadvantages.

More specifically, the invention relates to an adapter for connecting an electrical device with a plug to a wall socket, with a socket part suitable for receiving the plug of the electrical device and a plug part suitable for plugging into the wall socket, this adapter being generally characterized in that that the socket part and the plug part each form independent, separate components.

Preferably, but not exclusively, detachable clamping means are provided between this socket part and this plug part, which enable these two parts to be temporarily fastened to one another.

In any case, the invention advantageously allows, by ensuring a systematic division between the socket part and the plug part, a reduction in the number of different parts to be provided in order to cover all possible combinations of the different standards to be taken into account, which also advantageously minimizes the necessary investment costs.

The owner of an electrical appliance simply has to provide a socket part of this adapter that corresponds to the standard of this electrical appliance and then connect this socket part to a plug part that corresponds to the standard of the wall socket available to him.

In any case, the socket parts are interchangeable, and the same goes for the plug parts.

In other words, there is complete compatibility between any conceivable socket part and any corresponding plug part.

Consequently, it is sufficient for a national of any country in which a particular standard is in force to have a socket section in accordance with this standard and on the other hand, depending on its location, to provide one or the other plug part according to the other standard.

But, generally speaking, for a given country, the number of different versions that must be made available to a citizen of that country, i.e. the number of different parts with which they must be able to supply themselves, is advantageously reduced, since a single, always identical part is sufficient for the socket part.

In the event that there is a risk that the plug part of the adapter according to the invention will remain permanently plugged into a wall socket, this plug part has at least one associated retractable flap on its plug sockets, which is arranged to be movable between a rest position in which it covers the plug sleeves when in standby and a working position in which it releases them during operation.

This ensures safety under all circumstances.

In certain cases, when the contact means provided for a ground connection in the wall sockets is a socket, the socket part of the adapter according to the invention can itself be free of all electrical contact means in a simple and economical manner.

The socket part is therefore just a simple inactive part made of insulating material, which only has holes suitable for the passage of pins, namely for the pins of the plug of an electrical device adapted to the corresponding standard.

In fact, these pins only penetrate the socket part of the adapter according to the invention in order to cooperate directly with the sockets of the plug part which must be used simultaneously.

But according to a variant, in other cases the socket part of the adapter according to the invention has, on the one hand, at least one electrical contact means for interacting with a ground connection contact means on the plug of the electrical device in question and, on the other hand, a plug-in connection means for interacting with a complementary, corresponding plug-in connection means provided on the associated plug part, wherein the said contact means is electrically connected to the said connection means.

This ensures the ground connection in all cases. Further details and advantages of the invention emerge from the following description of an embodiment with reference to the attached schematic drawings. They show

Figure 1 is a partially sectioned perspective view of an adapter according to the invention,

Figure 2 perspective exploded view thereof,

Figure 3 is a partially sectioned perspective exploded view of the plug part of this adapter alone, with one of its components seen from above and the other components seen from below,

Figure 4 shows a reduced scale plan view of the Plug part of this adapter in the direction of arrow IV in Figure 2 in the rest position of its retractable flap,

Figure 4a is a plan view corresponding to Figure 4 for the working position of this retractable flap,

Figure 5, on the scale of Figure 4, a plan view in the direction of arrow V in Figure 2 of the underside of the socket part of the adapter according to the invention,

Figure 6 on the same scale a plan view in the direction of arrow VI in Figure 2 of the top of this socket part,

Figure 7 shows, on an enlarged scale, an axial section along the line VII-VII in Figure 2 of the adapter according to the invention after simple axial connection of its socket part with its plug part,

Figure 8 is a cross-section along line VIII-VIII in Fig. 7,

Figure 9 is a partial view according to section IX in Fig. 7 in axial section,

Figure 10 on the scale of Fig. 9 another partial view of the adapter according to the invention in axial section along line X-X in Fig. 7,

Figure 11 is a partial view in axial section analogous to Figure 9 after a firmer axial engagement of the socket part in the plug part, which is necessary for unlocking the retractable flap of the latter, Figure 12 is a cross-section analogous to Figure 8 after rotation of the socket part in relation to the plug part,

Figures 13, 14, 15, 16 are perspective views on a reduced scale of also usable plug parts, whereby the part corresponding to Fig. 2 is shown in each case and

Figures 17, 18, 19 show similar perspective views of socket parts that can also be used, whereby here too the part corresponding to Fig. 2 is shown.

As shown in these figures, the adapter 10 according to the invention, which is intended for connecting an electrical device (not shown) by means of a plug to a wall socket (also not shown), generally comprises, in a manner known per se, a socket part 10A suitable for receiving the plug of this electrical device and a plug part 10B suitable for insertion into a corresponding wall socket.

According to the invention, the socket part 10A and the plug part 10B each form independent, separate parts to be assembled.

In the design shown in more detail in Fig. 1 - 12, the 10A socket part corresponds to the standards applicable in France and Belgium.

It therefore comprises a base 12 of circular circumference surrounded by a collar 11, from which in an eccentric position a Pin 14 serves as a ground connection contact.

At the same time, the base 12 has two holes 15 of circular circumference spaced apart in the diameter direction for the passage of the phase pins of a plug conforming to the same standard.

For reasons that will become apparent later, the socket part 10A according to the invention in the embodiment shown further comprises, on the one hand, two mounting feet 16 which, in a diametrically opposed arrangement, extend the collar 11 downwards beyond the base 12 and which each have a bent edge 17 at their end that extends outwards, and on the other hand, alternating with the mounting feet 16 and arranged crosswise with them, two projections 18 which extend from the underside of the base 12 and, on its outer edge, also extend the collar 11 locally downwards, but at a much lower height.

In the embodiment shown in Fig. 1 - 12, the plug part 10B corresponds to the standard applicable in Germany, while the standards applicable in France and Belgium are also fully satisfied.

It therefore has two contact tongues 22 of the so-called "SCHUKO" type, which are arranged in two diametrically opposed lateral grooves 20 in a projection 21, as ground connection contact means, as well as two ribs 25 extending from flats 24, alternating with the contact tongues 22 and arranged crosswise with them.

At the same time, two phase pins 26, spaced apart in the direction of diameter, extend from the bottom of the projection 21, which has a substantially circular circumference, each of which is connected to one of two internal phase sockets 27. are electrically connected, whereby they are placed directly on them, for example as shown in the illustration.

In the embodiment shown, the phase sockets 27 are simply formed by pincer-shaped contact tongues.

Between the phase sockets 27 there is a ground connection socket 28 in the extension 21.

For reasons apparent below, this ground connection socket 28, which is also formed from two pincer-shaped contact tongues, is radially extended on at least one side of the axis of the plug part 10B.

In the embodiment shown, it is extended along a diameter of this plug part 10B, which runs perpendicular to the diameter along which the phase sockets 27 otherwise extend.

In fact, one contact tongue 22 is formed by a bent edge of one of the contact tongues forming the ground connection sockets 28 and the other contact tongue 22 is formed by a bent edge of the other, each with a corresponding passage in the side wall 29 of the extension 21.

For access to the ground connection socket 28, the base 30 of this extension 21 has two holes 32 spaced apart along the corresponding diameter and therefore arranged crosswise with the phase pins 26 (Fig. 7).

At its upper end, the attachment 21 is secured by a fixed Plate 34 is closed, the attachment being surmounted by a shaft 35 of larger diameter.

For example, the plate 34 is inserted as shown with a collar 36 into a collar 37 which extends the lateral wall 29 of the extension 21 over the bottom 38 of the shaft 35, the plate 34 being anchored in this collar 37 by projections 40 which are arranged diametrically opposite one another and engage in recesses 41 of the collar 37 (Fig. 3).

For reasons that will become apparent below, the collar 36 of the plate 34 extends set back in relation to its outer edge, so that this plate 34 extends slightly cantilevered in the protection of the shaft 35 above the collar 37 of the extension 21 at a distance from the bottom 38 of the shaft 35.

For access to the phase sockets 27, the plate 34 has two holes 42 spaced apart along a diameter.

According to the embodiment shown, these phase holes are each designed as an elongated hole along the same diameter.

For access to the ground connection socket 28, the plate 34 also has a ground connection hole 44 between the phase holes 42.

According to the embodiment shown in solid lines in the figures, this ground connection hole 44 has a circular circumference and is arranged in the center of the plate 34.

According to a variant shown in dashed lines in Figure 3, the bore can also be extended along a diameter that runs perpendicular to the diameter along which the phase sockets 27 extend, i.e. parallel to the underlying ground connection socket 28.

Outside its base 38, the shaft 35 of the plug part 10B thus formed has a collar 45 with a circular circumference.

Preferably, this plug part 10B also has, as shown, at least one retractable flap 47 associated with its phase sockets 27, which is arranged to be movable between a rest position (Fig. 4), in which it covers the phase sockets 27 when in standby mode, and a working position (Fig. 4A), in which it exposes them when in operation.

In the embodiment shown, this retractable flap 47 is arranged so as to rotate on the surface of the plug part 10B itself, above the plate 34 which closes off its neck 21, extending substantially at the same height as the free edge of the collar 45 of its shaft 35.

It comprises, on the one hand, holes 48 for covering the phase sockets 27 through the holes 42 of the underlying plate 34, this being the case when it is in the working position (Fig. 4A), and, on the other hand, a central hole 49 which is arranged in overlap with the hole 44 of the plate 34 and provides permanent access to the ground connection socket 28.

Like the holes 42 of the plate 34, the holes 48 of the retractable flap 47 is designed as an elongated hole, while its central hole 49 has a circular circumference.

However, as before, and as shown schematically in broken lines in Fig. 2, this central hole 49 may be extended along a diameter which is perpendicular to that along which the holes 48 extend.

In fact, the retractable flap 47, when rotated, is in engagement with the underlying plate 34.

For this purpose, it has two mounting claws 50 extending from its lower surface, which are arranged opposite one another in an opposite position and by means of which it is hooked into the peripheral edge of the plate 34 during rotation, whereby these mounting claws 50 each have hooking lugs 51 extending radially inwards for this purpose.

In the embodiment shown, the outer surface of these hooking lugs 51 is provided with a ramp so that the mounting claws form locking claws.

In other words, during assembly, the retractable flap 47 is inserted into the underlying plate 34, which in turn is fixed, for example by welding, to the collar 37 of the extension 21, by simply snapping it into place.

Once inserted, the retractable flap can no longer be removed.

For reasons that will become apparent below, the mounting claws 50 that it has extend slightly back from its outer edge in favor of the latter associated arched recesses 52.

At their outer ends, panels 53 extend to reinforce their strength.

At least along its outer edge, the retractable flap 47 extends at a distance from the plate 34 located underneath, for reasons that will also become apparent later.

In the embodiment shown, the plate 34 has a projection 55 in its central area (Fig. 7), on which the retractable flap 47 rests.

In any case, the outer edge of the retractable flap 47 also extends in the protection of the shaft 35 above the edge of the plate 34.

Finally, the retractable flap 47 comprises along its outer edge at least one locking claw 56 with which it engages in the rest position with a recess 57 in the underlying plate 34, and it is at least locally elastically deformable so that a pressure exerted in the axial direction on its outer edge in a straight line to this locking claw 56, as shown schematically by arrow F1 in Fig. 11, is sufficient to release it by elastic deformation from the recess 57 in the plate 34.

In the illustrated embodiment, the recess 57 of the plate 34 is an arcuate cutout in its outer edge, and the locking claw 56 of the retractable flap 47 has an opposing projection 58 for engagement therewith.

In fact, the plate 34 comprises two circumferentially spaced recesses 57, 60 for the locking claw 56 of the retractable flap 47, one, for example the recess 57, for the rest position of this retractable flap 47 (Fig. 8), the other, recess 60, for its working position (Fig. 12).

Likewise, in the actual embodiment, the retractable flap 47 has two oppositely arranged locking claws 56 arranged alternately with these mounting claws 50, and the plate 34 has two sets of recesses 57, 60 accordingly.

In the embodiment shown, the recesses 57, 60 thus present on the plate 34 are associated with portions of the outer edge of this plate 34 which extend from the regular part of this outer edge, while it is opposite to the regular part with which the retractable flap 47, via its mounting claws 50, engages the plate 34 during rotation.

Since the socket part 10A of the adapter 10 according to the invention has a ground connection pin 14 for cooperating with a complementary ground connection contact means on the plug of the electrical device concerned, the socket part 10A forms an active part in the embodiment shown in Figs. 1 to 12 and therefore also comprises, for cooperating with the pluggable connection means which is formed by the ground connection socket 28 correspondingly provided on the plug part, a complementary pluggable connection means, in the present case a pin 62 which extends along its axis from the inner surface of its base 12 with a suitable electrical connection between the contact means which is provided on the upper surface of this base 12, and the connecting means which this pin 62 forms.

In the embodiment shown, this electrical connection is ensured by a metallic connecting bar 63 which extends on the lower surface of the base 12 along a diameter thereof and into which the pins 14 and 62 are inserted, the pin 14 being guided through a hole 64 in the base 12.

Finally, between the socket part 10A and the plug part 10B designed in this way, there are preferably detachable fastening means which enable them to be temporarily fastened to one another.

In the embodiment shown in Figs. 1 to 12, these detachable fastening means are assembly means in the form of a bayonet lock.

For this purpose, the plug part 10B has two grooves 65, with which the two mounting feet 16 of the socket part 10A can each engage.

In the actual design, these grooves 65 are arranged on the inner surface of the collar 45 of the shaft 35 of the plug part 10B.

Each groove comprises an axial section 66 which extends from the free edge of the collar 45 and whose circumferential extension is at least equal to that of the mounting feet 16 of the socket section 10A, although in the actual design it is slightly larger than this, and a circumferential section 67 which in turn extends in extension of the aforementioned axial section 66 at a distance from the free edge of the collar 45.

At the same time, the arcuate cutouts 52 of the retractable flap 47 also have an extension in the circumferential direction that is at least equal to that of the mounting feet 16 of the socket part 10A, although they slightly exceed this in the actual design.

In the rest position of the retractable flap 47 (Figs. 4, 7 and 8), each of the arcuate cutouts 52 is located in a straight line with the axial portion 66 of the grooves 65 of the plug part 10B, so that the mounting feet 16 and the socket section 10A, by penetrating the axial portion 66 of these grooves 65 with their bent edge 17, come into engagement with these arcuate cutouts 52 together when this socket section 10A is brought into axial engagement with the plug part 10B.

For such an axial engagement, the socket part 10A rests with its projections 18 on the retractable flap 47 of the plug part 10B in a straight line to its locking claws 56.

It is therefore sufficient to continue this engagement with a small amount of force in order to achieve, as shown schematically by arrow F1 in Fig. 11, the local application of axial pressure on the retractable flap 47 and to obtain sufficient elastic deformation of this retractable flap 47 so that the projections 58 of its locking claws 56 come out of the corresponding recesses in the underlying plate 34 and so that this retractable flap 47 is freed from the latter.

Since the bent edges 17 of the mounting feet 16 of the socket part 10A are simultaneously in a straight line in front of the peripheral portion 67 of the grooves 65 of the plug part 10B, it is therefore sufficient to ensure the fastening of this socket part 10A to the plug part 10B to rotate the latter on itself in the direction corresponding to the peripheral portion 67.

The retractable flap 47, which is set in rotational movement by the socket section 10A due to the engagement of the mounting feet 16 of the same with their arcuate cutouts 52, itself rotates simultaneously in the same direction, as shown schematically by arrow F2 in Fig. 12.

Due to this rotational movement, which takes place around the axis of the pin 62 of the socket part 10A engaged with the earth connection socket 28 of the plug part 10B in the protection of the corresponding hole 44 of the plate 34 of the same, the holes 48 of the retractable flap 47 are respectively in overlap with the holes 42 of this plate 34, which allows access to the phase sockets 27 of the plug part 10B.

Since the socket part 10A is simultaneously attached to the plug part 10B by the corresponding bayonet lock, the adapter 10 according to the invention thus designed is therefore ready for use.

Any possible detachment of the socket part 10A from the plug part 10B is obviously done by reversing the previously described process

In addition, this socket part 10A can be assembled analogously to the above-mentioned steps with any of the plug parts 10B shown in Figs. 13 to 16, even if the components of the corresponding bayonet lock are not shown there.

In Fig. 13 there is a plug part 10B according to the standard in force in Italy, which for this reason has a pin 22' as a contact means for the earth connection between the phase pins 26 in line with them.

Fig. 14 is a plug part 10B according to the standard applicable in Great Britain.

Instead of a circular cross-section, the phase pins 26 have a flat shape.

In addition, the ground connection pin 22', which is also designed as a flat pin, is offset in relation to the phase pins 26.

Fig. 15 is a plug part 10B according to the standard applicable in Greece.

It comprises an extension 21' of the same type as the previously described extension 21 with the difference that this is equipped with a pin 22' arranged offset to the phase pins 26 as a ground connection means.

Like this ground connection pin 22', the phase pins 26 are also designed with a circular cross-section.

Fig. 16 is a plug part 10B according to the standards applicable in Switzerland and Spain.

As before, it includes a 21" approach.

But instead of an essentially circular Cross-section it has a boat-shaped cross-section.

It also comprises two strut phase pins 26 and one strut wet connection pin 22', each with a circular cross-section.

Any of these protruding plug parts 10B can also be assembled with any of the socket parts 10A shown in Figs. 17 to 19 instead of the socket part 10A described above.

Fig. 17 is a 10A socket part according to the standard applicable in Germany.

It comprises on the inner surface of its collar 11 on the one hand two contact tongues 14' as ground connection contact means and on the other hand two grooves 25' for interaction with complementary ribs.

As before, this socket part 10A further comprises on the lower surface of its base extending therefrom a ground connection pin 62 which extends along its axis.

In Fig. 18, on the other hand, the 10A socket section, which therefore corresponds to the standard in force in Italy, is completely free of electrical contact means.

It therefore forms an inactive part, which is, for example, realized by a single block of insulating material.

In the practical redesign, it therefore only has holes suitable for the pins, namely on the one hand, two holes 15, as before, for the passage of the phase pins, and on the other hand, a hole 62', which is arranged between the aforementioned holes 15 and in a row with them, for the passage of a ground connection pin.

In Fig. 19, which corresponds to the standards in force in Switzerland and Spain, the socket section 10A, as shown by the solid line, can also form an inactive part.

But its hole 62' is offset in relation to the holes 15.

In both cases, the plug pins of the electrical device to be connected simply pass through such an inactive part before reaching the corresponding sockets of the associated socket part.

To recall again, in the case of the plug part 10B, the corresponding ground connection socket 28 extends along a diameter for a possible displacement of the hole 62' provided for the passage of the ground connection pin as shown in Figure 19.

However, as shown in dashed line, according to a variant, the plug part 10B shown in Fig. 19 can also be provided with a ground connection pin 62 according to the previously described types of embodiment.

In Figs. 13 to 19, the socket part 10A and the plug part 10B have, in plan view, a curved rectangular perimeter, with convex sides and rounded corners, simply for aesthetic reasons.

This contour, which represents only one of other possible contours, is of course without influence on the features of the invention itself as set out in the claims.

The present invention is not limited to the embodiments described and illustrated, but encompasses all embodiments and/or combinations of its various elements.

In particular, it is not absolutely necessary to provide fastening means between the socket and plug used and, if such fastening means are provided, they do not necessarily have to be a bayonet-type fastening means.

For example, it could just as well be a clip fastener.

Likewise, the detachable earth connection means provided on the socket part and the plug part can be interchangeable, i.e. with a socket on the socket part and a pin on the plug part.

Claims (21)

1. Adapter for connecting an electrical device to a wall socket with a socket part (10A) suitable for receiving the plug of the electrical device in question and a plug part (10B) suitable for plugging into the corresponding wall socket, characterized in that the socket part (10A) and the plug part (10B) each form independent, different parts. 2, Adapter according to claim 1, characterized in that the plug part (10B) has at least one retractable flap (47) associated with its phase sockets (27) which is arranged to be movable between a rest position in which it covers the phase sockets (27) in standby mode and a working position in which it exposes them in operation. 3. Adapter according to claim 2, characterized in that the retractable flap (47) is arranged rotatably on the surface of the plug part (10B) itself, and in that it has holes (48) which can overlap with the phase sockets (27). 4. Adapter according to claim 3, characterized in that the retractable flap (47) is rotationally connected to a connected to the underlying fixed plate (34). 5. Adapter according to claim 4, characterized in that the retractable flap (47) has mounting claws (50) with which it is hooked into the outer edge of the underlying plate (34) during rotation. 6. Adapter according to claim 5, characterized in that the mounting claws (50) form locking claws. 7. Adapter according to one of claims 4 to 6, characterized in that the retractable flap (47) extends at least along its outer edge at a distance from the underlying plate (34), that it has at least one locking claw (56) with which it engages in a recess (57) of this underlying plate (34) in the rest position and that it is at least locally elastically deformable so that a pressure exerted axially on its outer edge in the direction of this locking claw (56) is sufficient to release it from the said recess (57) of the underlying plate (34) by elastic deformation. 8. Adapter according to claim 7, characterized in that the recess (57) of the underlying plate (34) is an arcuate cutout in its outer edge and that the locking claw (56) of the retractable flap (47) has an opposing projection (58) engageable therein. 9. Adapter according to claim 7 or 8, characterized in that the plate (34) located under the retractable flap (47) has two recesses (57, 60) for the locking claw (56) of the latter, one for its rest position, the other for its working position. 10. Adapter according to one of claims 7 to 9, characterized in that, in order to exert a local pressure on the retractable flap (47) of the plug part (10B) in the direction of its locking claw (56), the socket part (10A) has at least one projection (18) extending from the lower surface of its base (12). 11. Adapter according to one of claims 7 to 10, characterized in that the retractable flap (47) has two locking claws (56) arranged diametrically opposite one another. 12. Adapter according to claim 5 in conjunction with claim 11, characterized in that the retractable flap (47) has two mounting claws (50) alternating with its locking claws (56). 13. Adapter according to one of claims 1 to 12, characterized in that the socket part (10A) is free of any electrical contact means and represents an inactive part which only has holes (15, 62') suitable for the passage of pins. 14. Adapter according to one of claims 1 to 12, characterized in that the socket part (10A) on the one hand has at least one electrical contact means (14) for interacting with a ground connection contact means on the plug of the electrical device in question, and on the other hand a pluggable connection means (62) for interacting with a corresponding pluggable connection means (28) provided on the plug part (10B), wherein said contact means (14) has an electrical connection (63) with said connection means (62). 15. Adapter according to claim 14, characterized in that the connecting means (62) of the socket part (10A) extends along its axis. 16. Adapter according to claim 14 or 15, characterized in that the connecting means (62) of the socket part (10A) is a pin. 17. Adapter according to claim 16, characterized in that the connecting means (28) of the plug part (10B) is a socket which is radially extended on at least one side of its axis. 18. Adapter according to one of claims 1 to 17, characterized in that suitable detachable fastening means are inserted between the socket part (10A) and the plug part (10B) for a temporary connection of the same to one another. 19. Adapter according to claim 18, characterized in that the releasable fastening means are assembly means of the bayonet lock type, the socket part (10A) having two assembly feet (16) each suitable for engaging in two grooves (65) of the plug part (10B), each having an axial section (66) and a peripheral section (67). 20. Adapter according to claim 3 in conjunction with claim 19, characterized in that the retractable flap (47) of the plug part (10B), in order to set it in rotation, has two arcuate cutouts (52) which, in their rest position, are each located in extension of the axial portion (66) of the grooves (65) of the plug part (10B) and with which the mounting feet (16) of the socket part (10A) engage together when the latter is brought into engagement with the plug part (10B). 21. Adapter according to claim 10 in conjunction with claim 19, characterized in that the socket part (10A) has two projections (18) which are arranged alternately with the mounting feet (16).