NO337061B1 - socket - Google Patents

Description

BACKGROUND

Technical field

[0001] The present invention relates to connectors for connection to a power supply network, more specifically a socket with simplified insertion of a plug.

Known and related art

[0002] Movable electrotechnical equipment typically has an appliance cord with a plug, and is connected to a power supply network by inserting the plug into a socket that is permanently connected to the power supply network. Today, around 20 such connections are used in various countries. Common to all is that the terminals with applied voltage are accessible through contact holes in the socket and that the plug has protruding contact pins that fit into the contact holes. The shape of contact pins and corresponding contact holes varies. For example, blade-shaped contact pins are used in the US, while cylindrical contact pins and contact holes are common in Europe. Some contacts are polarized, i.e. certain contact pins must be connected to specific current-carrying phases called line (L) and neutral (N)-Other contacts are unpolarized, where it is irrelevant which contact pin is connected to current phase L or N. Both polarized and unpolarized contacts can be grounded or ungrounded. An earthed socket is described here, which has terminals connected to electrical ground in addition to the current-carrying terminals for the plug's contact pins. Because the earth terminals are fixed at ground potential, and consequently do not transmit electrical power during normal operation, one earth terminal can be left open in the socket. One ground terminal can also have a different design in different countries. For example, a spring-loaded grounding clip fitted to a slot in the plug is common in Germany and several other European countries, while a grounding pin fitted to a hole in the plug is common in France.

[0003] In order to facilitate the sale of electrical appliances and to make it easier for travelers to take electrical appliances with them from one country to another, electrotechnical equipment, including plugs and sockets, is becoming increasingly standardized. The US International Trade Administration (ITA) has assigned the letters A-N to the most common connectors, and a European norm, Certification of Electrotechnical Equipment (CEE) applies to electrotechnical equipment in most of Europe. For example, most electrical appliances in Europe outside of Great Britain and Ireland today are supplied with an earthed plug of type CEE 7/7, which is part of IT As type F. This plug is used as an example in what follows. A specialist can adapt the example to other contact types without any inventive effort. Other types of contacts are also described where relevant.

[0004] More specifically, figures la and lb show a plug 200 of type CEE 7/7, which is a hybrid between a German and a French standard. The original German plug is standardized as CEE 7/4 ("Schuko"), and defines two cylindrical contact pins 210 with length L = 19 mm, diameter d = 4.0 mm and distance S = 19 mm between the center axes as shown in fig. let. CEE 7/7 defines a plug with slightly different dimensions than those shown in figure la, but the socket according to CEE 7/7 accepts both new plugs of type CEE 7/7 and older plugs of type CEE 7/4.

[0005] Figure 1b shows the plug in Figure 1a seen from below. Here it appears that the plug has a hole 250 adapted to an earthing pin from the French standard. A metal sleeve in the hole 250 is connected to a metal plate in the grounding slot 212 from the German CEE 7/4. and on to an earth wire in the appliance cable. The maximum diameter a for the plug, sizes b, c for a guide nose 232 and other measurements can be found in CEE 7/7.

[0006] It is impractical to have to change the plug on lamps, ovens and other electrotechnical equipment in order to adapt it to the socket according to the invention. Because European electrotechnical equipment is supplied with a plug of the type shown in figures la and lb, one object of the invention is that a European implementation must be able to accept plugs of type CEE 7/7 and equivalent, but not necessarily all plugs that can be received in a socket of type CEE 7/7. In general, it is a purpose that the socket according to the invention should be able to receive a plug of a type supplied with equipment sold for household use, typically for 110 V or 220-240 V mains voltage.

[0007] Fig. 2a shows a schematic section through a commercially available, grounded socket 10 for the plug shown in figures la and lb. The variant shown has a cover that lies on the outside of a wall surface 15 and crescent-shaped grooves 14 (see fig. 2b) to guide the plug's contact pins towards contact holes 121. The socket 10 has a well with a depth less than the length of the contact pins in CEE 7/7, i.e. h < 19 mm. The contact pins 211 (fig. 1) can thus slide on the bottom surface of the well and/or in the guides 14 until they hit the holes 121, and the plug can then be pressed down until the contact pins hit the terminals 111, which are different terminals L and N in a polarized contact These terminals 111 is connected to the power supply network, which in this example has 220-240 V alternating voltage and delivers current up to 16 A. A radially biased earthing clamp 112 is connected to an earth wire in the power supply network. The electrical terminals L, N and ground are connected to wires and placed in a wall box 11 in a known manner.

[0008] Figure 2b shows the socket in Figure 2a seen from above. The circle drawn with a dot-dashed line corresponds to the section through the pressure plate shown with a dot-dashed line in figure 2a. This shows the edge of the wall box 11. The crescent-shaped grooves 14 serve to guide the plug's contact pins towards the holes 121, and are therefore deepest at the holes 121 and less deep towards the ends. Corresponding grooves are found in some commercially available sockets, e.g. in Elko model 1091. The grounding clamps 112 are schematically shown, and are biased radially inwards so that they will clamp against the grounding groove in a plug that is inserted into the socket.

[0009] The guides 14 shown in figures 2a and 2b guide the contact pins towards the contact holes 121, but it can still be difficult to align the contact pins, especially if the socket is placed in a place where the contact holes are not visible, or for people with impaired vision or dexterity. Sockets have therefore been developed with larger and deeper contact pin guides that guide the plug's contact pins towards the contact holes in the socket.

[0010] US 1 812 343 A describes a socket with a short and a long guide groove which guides contact pins on a plug towards respective openings in the socket when the plug is pressed against them. This also causes the plug to rotate in relation to the socket.

[0011] DE 653 597 C describes a corresponding socket with two opposite, half-moon-shaped concave surfaces which slope in opposite directions towards each contact hole so that the contact pins slide against the contact holes, and the plug rotates accordingly, when the plug is pressed against the socket.

[0012] DE 3 731 588 A1 shows a socket with a spring-loaded dust cover.

[0013] DE 2 457 072 Al describes an earthed socket with concave contact pin guides as described above. This contact is further developed with a base plate that can be displaced axially in the direction of the contact pins in DE 2701 188 Al against a spring force. The latter is considered the closest known technique.

[0014] . Some countries, for example Denmark, Finland, Norway and Sweden, require that sockets have child protection, i.e. equipment to prevent children from coming into contact with the power supply network. The child lock is typically a cover over the contact holes and/or a device that requires that the contact pins can only be pushed in if they are pressed against both contact holes at the same time. Other safety mechanisms are described in EP 2 385 588 Al,

AU 743 828 B2 and CN 203 135 105 U.

[0015] Existing outlets can be mounted on the outside of a wall in their entirety, or they can have permanent connections to the power supply network in a box embedded in the wall and only a cover on the outside of the wall. In both cases, it is desirable to be able to retrofit a socket in an existing installation.

[0016] The purpose of the present invention is therefore to produce a socket which satisfies at least one of the needs above and which preserves advantages from known technology.

SUMMARY OF THE INVENTION

[0017] This purpose is achieved with a socket according to claim 1.

[0018] More specifically, the invention produces a socket comprising a cover with a cylindrical well wall that has a larger diameter than a casing cylinder around an existing, predetermined plug, at least two contact holes adapted to receive contact pins for the transmission of electrical power, where each contact hole is located at the bottom of a concave contact pin guide. The contact holes and contact pin guides are placed on a pressure plate which is axially movable along the well wall between an outer position, where the pressure plate is biased outwards by a spring, and an inner position, where contact pins and earthing contacts on the plug inserted in the socket are electrically connected to their respective terminals adapted permanent connection to a power supply network. A first contact pin guide has a wide and deep part at a shallower and narrower tail end of a second contact pin guide and the second contact pin guide has a wide and deep part at a shallower and narrower tail end of the first contact pin guide. The pressure plate is rotatably movable about the rotational symmetry axis of the cylindrical well wall between a first orientation in which the contact holes are angularly offset from the terminals for transmission of electrical power, and a second orientation in which the pressure plate is oriented as in the inner position

[0019] The existing, predetermined plug is preferably a type that is supplied together with electrotechnical equipment in an area, for example type CEE 7/7 in Europe or a corresponding earthed plug in other parts of the world. The contacts on the plug include both contact pins and earthing contacts.

[0020] When the pressure plate is in the outer position, the contact pins can slide freely in the contact pin guides without being hindered by grounding terminals in the socket. When the contact pins have entered the contact holes, the plug is oriented and can be guided axially down the grounding terminals. The outward axial bias prevents the pressure plate from moving towards its inner position while the contact pins are pressed against the bottom of the concave contact pin guides. This makes it easier for people with disabilities to insert a grounded plug into a grounded outlet

[0021] When the terminals are connected to a power supply network, current-carrying terminals transmit electrical power to the contact pins and one or more ground terminal(s) connected to a ground wire in the power supply network connect the plug's grounding contact(s) to electrical ground potential. The terminals can be mounted in a junction box from a previously mounted socket, so that only the former cover is replaced with the cover of the invention which has an axially movable pressure plate. Alternatively, the terminals can be mounted in a junction box as part of the socket, so that new terminals must be connected to the power supply network in a known manner. In both options, the terminals are adapted for fixed connection to the power supply network. This simplifies the retrofitting of the invention in an existing facility. In addition, costs are reduced if the cover can be retrofitted over an already installed junction box.

[0022] The angular displacement makes it possible to prevent an object that is inserted into the contact holes from hitting the terminals that transmit current and voltage, and thus acts as a child lock.

[0023] In a preferred embodiment, the pressure plate is held in its inner position by a radially directed holding element. This prevents the pressure plate from moving outwards and pulling the plug with it, and is more important the stronger the pressure plate is biased. The radially directed element can be a fixed rib, particularly if the prestress is large.

[0024] In some embodiments, the radially directed element is radially biased inward from the cylindrical well wall. When the pressure plate has pushed such an element radially out against the well wall and passed a certain axial position, the prestressed element is moved onto the upper side of the pressure plate and holds it in its inner position. This can provide tactile feedback to the user that the plug is properly inserted. When the plug is pulled out, the biasing force of the radial retaining elements must be overcome without the plug being pulled out of the pressure plate.

[0025] Each contact hole preferably leads to a tunnel which extends axially in an elongated body. If a child sticks an electrically conductive stick into the contact hole and tilts the stick from side to side, the angular range of the tunnel openings is limited to arctan( D/ LJ, where D is the largest transverse dimension of the contact hole and Lt is the length of the tunnel. For example, the maximum angular range is reduced from approx. 70 ° for a contact hole through a plate of thickness Lt = 0.5D to less than 30° if the tunnel length is extended to Lt = ID This reduces the risk of a child getting hurt, thus increasing safety.

[0026] In an alternative embodiment, such a tunnel in an elongated body comprises an electrically conductive sleeve connected to a power-transmitting sliding contact offset from the contact hole. When the pressure plate with the contact holes is in the outer position, the sleeve is isolated from the sliding contact, so that the child with the stick does not come into contact with the live wires even if the child touches the electrically conductive sleeve. When the pressure plate is in its inner position, the sliding contact is closed so that electrical voltage is transferred to the contact pins through the electrically conductive sleeves. An electrically conductive sleeve attached to the pressure plate can clamp around the contact pins in the same way as the sliding contacts in a traditional socket, and possibly adapted so that the pressure plate follows the plug out in embodiments with radially biased holding elements.

[0027] Childproofing can be further improved by aligning the contact holes in the outer position against an electrically insulating element placed within the pressure plate. In embodiments where the pressure plate is only moved axially, a child lock from known technology can be used. The insulating elements are then plates that can only be moved away from the contact holes when two contact pins are pressed against them at the same time. In embodiments where the pressure plate is rotated about the central axis between the outer and inner position, an insulating sleeve can be fitted, for example in the extension of an elongated tunnel. The rotational movement when inserting the plug will then displace the contact hole from the insulating sleeve to a current-carrying terminal.

[0028] A frustoconical transition is preferably placed between a top surface of the cover and the cylindrical well wall of the socket. This transition acts as a funnel, and guides the plug towards the well and pressure plate. Inserting the plug is thus further simplified.

[0029] Other features and details of the present invention emerge from the independent claims and the subsequent detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The invention is described in more detail in the following by means of examples of embodiments with reference to the attached drawings, where: Fig. la illustrates a known plug which should be able to be used with the present invention; Fig. 1b shows the plug in fig. let seen from below; Fig. 2a is a schematic section through a known, grounded socket; Fig. 2b shows the socket in fig. 2a top view; Fig. 3a shows a plug inserted in a socket according to the invention; Fig. 3b shows an embodiment of a pressure plate for use in the invention; Fig. 4 is a perspective view of a preferred embodiment; Fig. 5 shows a detail from Fig. 4; Fig. 6 is a plan view of the preferred embodiment with the pressure plate in the outer position; Fig. 7 is a first schematic section through the embodiment in Fig. 6;

Fig. 8 shows the embodiment in Fig. 6 with the pressure plate in an inner position; and

Fig. 9 is a second schematic section through the embodiment in Figures 3-8.

DETAILED DESCRIPTION

[0031] Figures 1 and 2 show known technology, and are described above.

[0032] Figure 3a illustrates a plug 200 inserted into a stem connector 100 according to the invention. In this example, the plug 200 is of type CEE 7/7 and the socket 100 is adapted to this plug and compatible types.

[0033] The shown embodiment of the socket 100 is suitable for wall mounting, and for this purpose has a connection box 110 that fits into a standard wall box 11 (Fig. 2a), and a cover 120 that covers the wall box. The opening 113 is for a cable from the power supply network, in this example a cable with an earth wire and phases L and N as in Fig. 2a. These must be connected electrically to electrotechnical equipment through an appliance cable (not shown) through the opening 202 in the plug 200.

[0034] To facilitate the description, an imaginary central axis z through the socket 100 is drawn. This z-axis coincides with the rotational symmetry axis of a cylindrical well wall 130 with a diameter larger than a cylinder wall or casing cylinder 230 around the plug. The terms "axial" and "radial" refer in this description to the central axis z. When the plug is inserted, as in Fig. 3a, the cylinders 130 and 230 therefore run coaxially about the central axis z, and both contact pins and all earthing contacts on the plug are axially aligned.

[0035] A frustoconical transition 123 guides the plug towards the well enclosed by the well wall 130 when the plug is inserted.

[0036] Electric ground potential is transferred through two diametrically opposed grounding clamps 112 (not shown in Fig. 3a) to complementary grounding tracks 212 on the plug. For this, the grounding clamps are radially biased inwards towards the central axis z, and slide along the axially directed grounding groove 212 when the plug 200 is inserted or withdrawn. The contact pins of the plug (not shown) slide correspondingly axially along complementary sliding terminals. What is here called axial displacement is therefore generally used to create electrical contact between complementary contacts on the plug and terminals in the socket, for example grounding clamp/grounding groove and contact pin/sliding terminal. As mentioned, contact pins for electrical phases sit on the plug, but the conventional contact can also have a contact pin for earth which is inserted into a sliding contact (250 in fig. lb) by axial displacement.

[0037] The plug's cylindrical covering surface 230 is interrupted by a guide surface 231 which runs axially and parallel to the axis through the diametrically opposite grounding grooves 212. A corresponding surface can, if desired, be provided in the well of the socket, for example to satisfy given standards. In principle, however, any cylindrical surface 230 fits where a part 2el is cut away into a cylindrical surface with a larger diameter. The well in the socket 100 is therefore shown as a straight cylinder without guide surfaces adapted to local standards.

[0038] The guide rib 232 on the plug 200 can have a corresponding groove in the well of the socket, but this is again an adaptation that is covered by the invention. As long as the outer surface of the guide rib 232 lies on or within the (imaginary) casing cylinder in continuation of the surface 230 of the plug, the plug 200 will be able to be inserted into a cylindrical well with a larger diameter.

[0039] Fig. 3b illustrates a pressure plate 140 for use in the invention. The pressure plate 140 can generally be moved axially along the well wall 130 on the socket 100, and for this can have radially directed pins 143 that fit into corresponding grooves in the cylinder wall 130 and/or radially directed grooves 144 adapted to elements that project radially inward from the cylindrical well wall 130 in various embodiments. For example, grounding clamps 112 can pass through slots 144 in the pressure plate when the pressure plate 140 is displaced axially in the socket 100. In general, therefore, radially directed guide elements such as pins 143 and/or slots 144 can be distributed along the circumference of the pressure plate 140.

[0040] In this example, the pressure plate 140 has axially directed contact holes 121 for two cylindrical contact pins on a plug of type CEE 7/7. The contact holes 121 are located at the bottom of concave contact pin guides 141 and 142, which have the same function as the crescent-shaped guides 14 shown in Fig. 2b. The concave contact pin guides 141 and 142 thus guide the contact pins 21 towards the contact holes 121 when the plug 200 is pressed axially against the pressure plate 140 in the direction into the plane of the paper in Figure 3b. This applies regardless of where or how the contact pins are placed against the contact plate 140. The plug 200 will rotate about the central axis z when the contact pins slide along the bottom of the contact pin guides 141 and 142.

[0041] Figure 4 shows the pressure plate 140 with the contact pin guides 141 and 142 in an inner position. The pressure plate has an outer position where grounding terminals such as grounding clamps 212 and a grounding pin (not shown) adapted to the grounding hole 250 in fig. lb is completely or partially hidden. In the outer position, the contact pins can therefore slide unimpeded by grounding terminals along the bottom of the concave contact pin guides 141 and 142 towards the contact holes 121.1 a polarized contact, it is an advantage that the grounding element protrudes slightly from the pressure plate in the outer position, so that the contact pins are guided towards their respective terminals L and N. For example, the ground pin in a polarized French plug may protrude slightly above the top surface of the pressure plate when it is in its outer position. When the contact pins are guided into the contact holes 121 by the contact pin guides 141 and 142, there are then two possibilities. Either the contact pins are correctly oriented, so that the grounding pin slides into the grounding hole 250, or the orientation is not correct, so that the grounding pin prevents further axial movement of the plug 200.1 in the latter case, it is sufficient to pull the plug out a little, correct the orientation (rotate the plug 180 ° about the central axis in this example) and insert the contact pins into the contact holes with the correct orientation. In an unpolarized contact, such as the "Schuko" contact in this example, the orientation of the contact pins does not matter, and both possible orientations are therefore correct orientations.

[0042] When the contact pins are placed in the contact holes 121 with the correct orientation,

the pressure plate is moved together with the plug to the inner position shown in Figure 4. This inner position can preferably only be reached when the plug 200 is inserted, and Figure 4 shows the pressure plate is in its inner position for illustration purposes only. As shown in fig. 4, the pressure plate is guided axially over an earthing clamp 112, which is thus electrically connected to the earthing groove 212 on an inserted plug. Similarly, an axial displacement will drive an axially oriented ground pin into a complementary hole, the hole 250 in Fig. 1b in this example, on a correctly oriented polarized plug.

[0043] The pressure plate 140 with the contact pin guide 142 can be moved axially along the grounding clamp 112. The grounding clamp 112 can thus also serve as an axial guide for the pressure plate. To prevent the pressure plate from tilting about its axis between diametrically opposed earthing clamps 112, the pressure plate 140 can advantageously be equipped with guide walls (not shown) which run parallel to the sides of the earthing clamp 112.

[0044] The pressure plate 140 must be able to withstand a certain axial force in its outer position so that the contact pins can slide along the concave contact pin guides 141 and 142 without the pressure plate being displaced towards the inner position shown in figure 4. The pressure plate is therefore biased outwards by a spring when it is in its outer position. To keep the pressure plate in its inner position, radially directed holding elements can be mounted, in fig. 4 represented by the ground clamp 212 and a ball 146, both of which are biased radially inward by a spring force. When the plug is inserted, the radial biasing forces must be overcome before the retaining element snaps into place over the pressure plate. The user holding the plug 200 can feel more or less clearly that such an element, for example the ball 146, is slipping into place. With sufficient radial bias, the user is given clear tactile feedback that the pressure plate is in its inner position, and thus that the plug is fully inserted.

[0045] Figure 5 shows the detail circled in Figure 4. The cover 120, the conical guide 123, the well wall 130 and the concave contact pin guide 142 can be recognized from Figure 4. The grounding clamp 112 is resilient and biased radially inwards. When the pressure plate is moved axially along the well wall 130, the earthing clamp 112 is pushed radially out into a recess 114 in the cylindrical well wall. When the pressure plate has passed and is in its inner position, the ground clamp 112 rests against the pressure plate, and thus exerts an axial force on the pressure plate which helps to keep the pressure plate in the inner position shown in figure 4. It is understood that the ball 146 in figure 4 can is moved radially outwards in a corresponding manner, and that a suitable number of radially biased elements 112, 146 together can overcome the spring force needed to hold the pressure plate in its outer position while the contact pins slide in the contact pin guides 141, 142 when the plug is inserted. In such an embodiment, the pressure plate must be equipped with clamps or similar, so that it can be pulled out together with the plug. An electrically conductive sleeve fitted in the contact hole can act as a clamp around the contact pins of the plug and is described in more detail below.

[0046] Figure 6 shows a preferred embodiment, where the pressure plate with the contact pin guides 141 and 142 is angularly offset in relation to the cover 120.1 this example is

the axis 122 through the center of the contact holes 121 rotated 30° clockwise about the central axis z in relation to the lower edge of the cover 120. The angular displacement is preferably sufficient so that the contact holes 121 are not aligned with the alternating current phases behind the cover 120, but the angle of 30° shown is otherwise random selected. In this embodiment, the pressure plate 140 functions as a child safety device in that an object inserted axially through a contact hole 121 does not come into contact with a current phase, i.e. one of the power-transmitting terminals L or N.

[0047] Figure 7 is a section along plane VII-VII in Figure 6., ie through the center of a contact hole 121 seen along the axis through the center of the contact holes. The cover 120 is cut as in Figure 2a. The socket 100 is mounted on a wall surface 15, and the connection box 110 is adapted to a standard wall box 11 recessed behind the wall surface 15 in a known manner. The junction box 110 contains sliding contacts or sleeves for contact pins connected to alternating voltage phases L and N as in Figure 2a. Typically, the junction box 110 and cover 110 are supplied as a unit. However, it is possible to make a cover 120 with an axially displaceable pressure plate adapted to an existing junction box.

[0048] In Figure 7, the pressure plate 140 is in its upper position at the bottom of the blunt-conical guide surface 123. The guide surface 123 and the concave contact pin guide 141 in the pressure plate 140 are adapted to guide a contact pin towards the contact hole 121. The section shows the tail end of the second contact pin guide 142 , which guides the second contact pin towards a corresponding contact hole hidden behind the shown contact hole 121.

[0049] It appears from Figure 7 that the contact hole 121 is not aligned with the current-carrying slide contacts or sleeves L and N. Furthermore, the contact hole at the bottom of the concave contact pin guide 141 is the opening to an elongated tunnel. The tunnel is in reality just an extension of a short cylindrical contact hole 121 through the pressure plate. An elongated object which is inserted through the elongated tunnel 121 shown can be moved less laterally than a corresponding object which can be tilted freely about a center in a hole in a thin plate. More specifically, the angular range of the tunnel openings is limited to arctan( D/ LJ, where D is the largest transverse dimension of the contact hole and Lt is the length of the tunnel. For example, the maximum angular range is reduced from approx. 70° with a plate having thickness Lt = 0.5D to less than 30° with a tunnel length Lt = 2D. This reduces the risk that a child can stick an object through the hole 121 from the upper side and thus inadvertently come into contact with one or both of the current-carrying phases L and N. If desired, the junction box 110 can be equipped with an electrically insulating blocking element (not shown) in the extension of the hole or tunnel 121 in Figure 7, so that it is not possible to insert an object into the hole before the pressure plate 140 has been rotated about the central axis z and the hole 121 has thus been displaced away from the locking element.

[0050] In Figure 7, an earthing rail is shown connected to the earthing clamps 112 mounted on a cylindrical pin 115 at the central axis z.

[0051] The grounding rail can be fixed in relation to the well wall 130 as in a traditional socket. A corresponding pin is used in traditional sockets, and it is therefore possible to make a cover according to the invention with an earthing pin that fits in an earthing hole in an existing installation.

[0052] Alternatively, the ground rail can be attached to the pressure plate 140, and the cylindrical pin 115 can still be inserted into an existing junction box. In this variant, the cylindrical pin 115 functions as a shaft for rotation about the central axis z, so that a grounding pin for a polarized plug (the hole 250 in Figure 1b) is fixed in relation to the pressure plate 140 and can thus protrude above the pressure plate as described above.

[0053] The pressure plate 140 is biased axially outwards, ie in the z direction, by a spring 145.1 the embodiment of Figure 7 and in an embodiment where the pressure plate is only moved axially, the spring 145 must have sufficient stiffness to return the pressure plate 140 to the upper position, but not so great stiffness that it pushes the plug 200 out of the socket. The spring 145 can be one or more spiral springs. In embodiments where the pressure plate 120 can rotate about the z-axis, however, spiral springs require a separate sliding coupling, while leaf springs and disc springs have a surface along which the pressure plate can be rotated. The spring 145 is therefore shown schematically as an arc which preferably represents a leaf spring or a plate spring. It is particularly noted that such a leaf spring or plate spring can be clamped in a center plane for the axial movement. When the pressure plate 140 passes the center plane, such a leaf spring or plate spring will curve in the opposite direction, thus pushing the pressure plate in towards the electrically conductive contacts L and N. This may be useful if the plug is attached to the pressure plate.

[0054] Figure 8 corresponds to Figure 6, but the pressure plate is rotated so that the axis 122 through the center of the contact holes 121 runs parallel to the edge of the cover and is aligned with underlying conductive contacts. The top plate is further shifted to the inner position so that the earthing clamps 112 are visible.

[0055] Figure 9 is a section through plane IX-IX in Figure 8, i.e. centrally through

the socket along the axis 122 . The top plate 140 is in the inner position, and the contact holes 121 are aligned with their respective sliding terminals in the junction box 110. It is understood that a cable from the power supply network is fed in through the wall box 11 and hole 113 in the junction box for electrical connection as illustrated in figure 7, but which does not is shown in figure 9.

[0056] The rotation of the pressure plate 140 about the central axis z from the orientation shown in Figures 6 and 7 to the orientation shown in Figures 8 and 9 has, as mentioned, aligned the contact holes 121 with their respective sliding contacts in the junction box. Such a rotation can be made practically possible by equipping the cylinder wall in the well with axial ribs 131 directed radially inwards, so that the top plate 140 can slide on top of them. The rotation can be stopped with a radially directed element, for example a wall or track 13 as shown in the traditional socket shown in Figure 2b. In the example here, the slot 13 can be adapted to the nose 232 of the plug 200 shown in Figure 3a. The earthing clamp 112 and the top of the slot for the rib 232 are 90° apart, and can, if desired, serve as a support for the top plate 140 during this rotation instead of or in addition to own ribs 131 in the cylinder wall.

[0057] The rotation is preferably smaller than the angular distance between ribs and other radially directed elements. In this example, the rotation is 30° about the z-axis. Figure 9 suggests 8 radially aligned elements at 45° intervals, of which two ribs 131, one ground clamp 112 and two walls 13 are shown in the figure. As long as the rotation is less than the angular distance between the radially directed elements on the cylinder wall 130, grooves in the pressure plate 140 do not slide over any radially directed element until it is aligned over ribs and grounding terminals and thus can be moved axially.

[0058] In Figure 9, the pressure plate 140 is rotated and moved axially inwards along the ribs 131 from the position in Figure 7. The distance from the top of the pressure plate 140 to the sliding contacts in the junction box is shorter in Figure 9 than the contact pins on the plug, i.e. less than 19mm in the example here . This limits the length of the conical elements around the contact holes 121.

[0059] The spring 145 is compressed by the axial displacement of the pressure plate 140. The spring force is proportional to the compression and the stiffness of the spring, and must be overcome by the plug's friction against fixed parts in the socket. If not, the spring force will push the plug out of the socket.

[0060] In an alternative embodiment, the order of rotation and axial displacement can be reversed. When the plug is inserted, the pressure plate 140 is first displaced axially along the ribs 131, and then rotated under the ribs 131. Then the spring force from the spring 145 can be increased because it presses the top plate against the bottom of the axially directed ribs 131. When the plug is to be pulled out, it is first rotated the pressure plate until grooves in the pressure plate are aligned with the ribs 131, and the spring 145 contributes a force which pushes the plug towards the outer position.

[0061] In a variant, the rotational and axial movements can be combined into a screw movement. The plug 200 then rotates about the z-axis while the contact pins slide along the surfaces in the troughs 141 and 142 towards the contact holes 121 as described above, and then slide axially down into the holes 121. The rotational and axial movement of the pressure plate 140 then follows essentially the same direction.

[0062] In yet another variant, the sliding contacts 111, which are shown as cylinders in Figure 9, are edge contacts, and the contact holes 121 have electrically conductive sleeves on the inside. These sleeves preferably clamp around the contact pins when the plug is inserted, so that the pressure plate follows when the plug is pulled out. When the pressure surface is in the outer position shown in Figures 6 and 7, there is no contact between electrically conductive surfaces in the contact holes 121 and the current phases.

[0063] It is understood that any contact which connects the contact holes to their respective current phases in the inner position and breaks the connection in the outer position can be used in a socket with axial movement. Similarly, a contact that is made or broken by a rotation can be used in variants with a pressure plate that rotates about the z-axis. An axial movement combined with a rotation in a freely chosen order can therefore produce electrical contact between electrically conductive surfaces in the contact holes 121 in the top plate 140 and sliding contacts 111 firmly connected to the power supply network, also if the sliding contacts 111 are not axially aligned cylinders in the extension of the holes 121 as shown on the drawings.

[0064] The invention is described with reference to an example with a socket for a plug of a certain type, but the patent protection is defined by the subsequent patent claims.

Claims (8)

1. Socket (100) comprising a cover (120) with a cylindrical well wall (130) having a larger diameter than a casing cylinder (230) surrounding an existing, predetermined plug (200), at least two contact holes (121) adapted to receive contact pins (211) for the transmission of electrical power, where each contact hole (121) is located at the bottom of a concave contact pin guide (141, 142), where the contact holes (121) and the contact pin guides (141, 142) are placed on a pressure plate (140) which is axially movable along the well wall (130) between an outer position, where the pressure plate is biased outwards by a spring (145), and an inner position, where contact pins (211) and earthing contacts (212, 250) on the plug (200) inserted in the socket (100) are electrically connected to their respective terminals (111, 112) suitable for fixed connection to a power supply network, characterized in that a first contact pin guide (141) has a wide and deep part at a shallower and narrower tail end of a second contact pin guide (142) and the second contact pin guide (142) has a wide and deep part at a shallower and narrower tail end of the first contact pin guide (141), and the pressure plate (140) is rotatably movable about the rotational symmetry axis (z) of the cylindrical well wall (130) between a first orientation where the contact holes (121) are angularly offset from the terminals (111) for the transmission of electrical power, and a second orientation where the pressure plate (140) is oriented as in the inner position. 2. Socket (100) according to claim 1, where the pressure plate (140) is held in its inner position by a radially directed holding element (112, 146; 131). 3. Socket (100) according to claim 2, where the radially directed holding element (146) is radially biased inwards from the cylindrical well wall (130). 4. Socket (100) according to one of the preceding claims, where each contact hole (121) leads to a tunnel which extends axially in an elongated body (124). 5. Socket (100) according to claim 4, where the tunnel in the elongated body (124) comprises an electrically conductive sleeve connected to a power-transmitting slide contact on the outside of the elongated body (124), and the power-transmitting terminal (111) in the socket is a edge contact angularly offset from the elongate body in the outer position so that electrical contact is made when the pressure plate (140) is rotated from the outer position and the electrical contact is broken when the pressure plate is rotated back to the outer position. 6. Socket (100) according to claim 5, where the electrically conductive sleeve is adapted to clamp around a contact pin so that the pressure plate is pulled out together with the plug. 7. Socket (100) according to one of the preceding claims, where the contact holes (121) in the outer position are aligned with an electrically insulating element placed within the pressure plate (140). 8. Socket (100) according to one of the preceding claims, further comprising a blunt-conical guide surface (123) between a top surface of the cover (120) and the cylindrical well wall (130).