Patent Publication Number: US-10784637-B2

Title: Comfortably operated travel plug adapter

Description:
FIELD OF THE INVENTION 
     The present invention relates to a travel plug adapter, which will also be referred to herein as a travel adapter, for short. Using such an adapter it is possible to insert power plugs of a certain (domestic) standard into the outlets present at the travel destination. To this end, the travel plug adapter needs a plug receptacle of a first standard and a power plug of another standard. In this case, the issue more precisely is a travel plug adapter that can be inserted into outlets of at least a first standard and a second standard. To this end, power plugs of a first standard and a second standard may be used alternatively in the travel plug adapter. 
     BACKGROUND OF THE INVENTION 
     Travel plug adapters or travel adapters of this type are being used more and more in times of increasing global travel and commerce. There is therefore a need for compact, easily transportable travel plug adapters that are suitable for outlets of a number of different standards. 
     Chinese patent application CN 101872911 A discloses a travel plug adapter having an essentially round housing. Power plugs are housed in the interior of the housing and may be moved out of the housing. In this manner at least three different types of power plugs may be used. The desired power plug is selected in that the upper housing part is rotated relative to the lower housing part. The upper housing part has an individual actuation slider that projects outward. This actuation slider may be caused to engage with various power plug elements. To this end the slider is rotated into a position above the power plug that is to be moved out of the housing from below. 
     This travel plug may be useful for many purposes. However, it would be desirable to provide a travel adapter which can be operated more easily still. In particular, it would appear to be advantageous if different plugs are assigned different control elements and if the plug can be transferred into the usage position by operation of the assigned control element. 
     German patent DE 10 2011 014 920 B4 discloses another travel adapter, which is called a universal plug adapter. In this travel adapter, a plurality of sets of pins are provided in an exterior housing. Each set of pins is connected to a control element with which it may be moved from outside. The control elements are guided for this purpose in the housing by slide slots. The control elements are also guided using a blocking plate provided inside the exterior housing. This blocking plate has a guide track, and the control elements can move through the recesses thereof. The guide track provides an upper end position and a lower end position. The blocking plate is resiliently pre-stressed so that a control element may be securely retained in the upper end position or in the lower end position. The control element, and thus the corresponding set of pins, may be released from the end positions and moved upward or downward in that a selector lever also provided outside in addition to the control elements is actuated. Pressing this selector lever moves the blocking plate against the spring force. In this way the pins may be moved out of their upper or lower end position using the control elements. 
     In this solution, the outer control elements are used both for moving the sets of pins out of a first end position, a standby position, into a second end position, a usage position, and for locking the sets of pins in these positions. It is a drawback that the selection lever must also be operated during the movement of the sets of pins using the control elements. This prevents comfortable one-hand operation. The control elements also take up a lot of space on the plug surface. This prevents a free design-oriented configuration and attaining a compact structural form. 
     The object of the present invention is to make available an improved travel plug adapter that avoids the drawbacks of the prior art. The travel adapter should be able to be produced cost-effectively and reliably, should be easy to transport and operate, and should be very safe electrically. 
     The inventive travel plug adapter has a housing that may have various shapes. For instance, as a rule a block shape is practical for transport. However, the mechanics of the travel plug adapter are designed such that the housing shape may largely be freely selected. It is advantageous when the housing has at least one flat side, but the mechanics may also be adapted to curved housing surfaces. The housing may be embodied in one piece or in a plurality of pieces. It has proved useful to embody the housing in two parts, specifically with a lower housing part and an upper housing part. These may be detachably connected to one another, for instance using mechanical means, usefully using a screw connection. 
     The housing should have at least one plug receptacle. The latter is usefully provided on the housing upper side. The plug receptacle may have different shapes, depending on the type of power plug (hereinafter “plug” for short) to be received. For instance, if a Schuko plug is to be received, the plug receptacle will have an essentially cylindrical depression and in addition female connectors for receiving the contact pins of the Schuko plug. For other types of plugs, no depression or groove is necessary. It may be useful to provide a flat upper housing side in which a plurality of female contacts are provided. As a rule, at least two female connectors should be provided that form a female connector pair for receiving a plug of a standard. It may be useful to provide a plurality of female connector pairs in order to be able to receive a plurality of plugs of different standards. If the plugs also have grounding conductors and the plug receptacle is intended to provide the opportunity of grounding, as a rule it is also necessary to provide a third female connector or a third contact per plug to be received. 
     The travel plug adapter should furthermore have at least a plug of a first standard and a second plug of a second standard. (Such plugs are sometimes also called plug-in pin sets). The plug of the first standard may be, for instance, an EU plug, and the plug of the second standard may be a US plug. The plugs may have two pins, that is, they may not be grounded, or they may have three pins, so that a grounding pin may be provided. The present travel plug adapter is thus suitable for use in more than one country. Usefully, and as a rule, it is also necessary for the first plug and the second plug to be used alternatively. 
     The travel plug adapter may also comprise three or more plugs. Travel plug adapters with three or four plugs have proved to be very useful. At least one of the plugs, but as a rule all of the plugs, may be moved from a standby position, in which the plug is essentially disposed in the housing, to a usage position. In the usage position, the plug is usably disposed entirely or at least in part outside of the housing. Often it is possible for the plug to be moved completely back into the housing when it is returned to the standby position. It is useful that the plug may be moved far enough back into the housing that it is not in the way of other plugs. 
     The first plug is connected to an actuation slider for moving it from the standby position into the usage position. The second plug is also connected to an actuation slider for moving it from the standby position to the usage position. Thus the travel plug adapter has at least a first actuation slider and a second actuation slider. The actuation sliders may usefully be embodied in a button-like manner so that they are easy to move with one finger. For the actuation sliders, slide slots are provided in the housing. Slide slots may also be connected to one another so that a guide track for the actuation sliders results. As a rule it is useful to provide one slide slot per actuation slider and to arrange these slide slots parallel to one another. 
     A sliding selector that may be moved into at least a first position and a second position may be provided on the travel plug adapter. This sliding selector releases, alternatively, in its first position the first plug and in its second position the second plug, so that the plug can be moved into the usage position. For this purpose the sliding selector has a blocking element, and for example cams can be used as blocking element, which cams engage with the displacement track. However, within the scope of the present invention it is not necessary to provide such a sliding selector. Said sliding selector is optional and can be used in addition to the means described later. 
     Since the travel plug adapter should always be constructed compactly, the actuation sliders are generally situated very close to one another. It may therefore easily happen, for instance, that a finger is not placed precisely on the actuation slider and an adjacent actuation slider could be inadvertently displaced at the same time. However, since the present invention only permits the actuation of one plug, and thus (as a rule) only one actuation slider, as well, the actuation slider that is inadvertently also touched does not move (or it does not move the associated plug, at least). This renders operation of the travel plug adapter more error-tolerant. 
     It is useful, as mentioned, when the housing of the travel plug adapter has slide slots or similar recesses. The actuation sliders may run in these slide slots. A slide slot may also be provided additionally for a sliding selector. Slide slots permit the movement of a slider while it is also being guided. Thus they represent an advantageous and cost-effective mechanical solution. 
     Since, as a rule, a plurality of actuation sliders are provided on the travel plug adapter, it is particularly advantageous when they may be guided in the slide slots in a simple manner. In the context of the present invention, the actuation sliders must only cause the movement of the plugs, as a rule an up and down movement. The actuation sliders (in contrast to other common adapters) do not have to lock the plugs in the usage position, nor ensure that only one plug may be selected at any time. Because the actuation sliders in the context of the present invention are permitted to carry out only one function, they may be easily and reliably guided in slide slots. If the actuation slider was spring-loaded, for instance, guidance in a slide slot would be less user-friendly, as a rule, because the slider would tend to cant, would run “hook-like,” and would certainly have greater resistance. 
     A travel plug adapter can usefully have at least a first plug of a first standard and a second plug of a second standard. Here, each plug is assigned an actuation slider. Furthermore, each plug is to be assigned a blocking element, i.e. the first plug is assigned a first blocking element and the second plug is assigned a second blocking element. This blocking element blocks the displacement of the plug between the standby position and the usage position when the movement of the blocking element is blocked. 
     Furthermore, at least one blocking slide is provided, which in a first position releases the path of the first blocking element and in a second position blocks the path of the first blocking element. Here, the second blocking element can act on the position of the blocking slide. The at least one blocking slide can thus interact with the first and the second blocking element such that the movement of at least one blocking element is blocked. 
     As explained, it is desirable for safety reasons alone that only the first plug or the second plug can be transferred, alternately, into the usage position. In order to achieve this, a certain cooperation between the plugs is thus necessary. This cooperation is conveyed within the scope of the present invention by the blocking slides. Because the second blocking element acts on the position of the blocking slide, it can ensure that the blocking slide blocks the displacement of the first blocking element and therefore of the first plug. 
     The blocking slide can be guided in different ways, for example it could run on a pole which engages around the slide or it could also be supported by other housing parts, such as a housing wall. It is useful when the blocking slide is guided on a displacement track. This track supports the slide on one side, and can also surround it in a U-shaped manner, i.e. for example the underside can provide a track and at the same time can provide an additional guide to the opposing sides of the blocking slide. 
     It is also expedient when the at least one blocking slide is resiliently pre-stressed towards an end of the displacement track. The blocking slide is then pressed permanently against the end of the displacement track. This can be achieved expediently with a spring at the opposite end of the displacement track, for example with a coil spring. The pre-stressing of the blocking slides means that they are always held in predetermined positions at an end of the displacement track. 
     Particularly if a number of blocking slides are used on the displacement track, the position of the gaps between two blocking slides is thus also predetermined. A blocking element can engage in such a gap between the blocking slides. This makes it possible for the plug assigned to the blocking element to be transferred into the usage position. 
     It is expedient that, when a blocking element engages in a gap between two blocking slides or between a blocking slide and an end piece of the displacement track, the engagement of a further blocking element in such a gap is not possible. Accordingly, it is expedient that the length of the displacement track is dimensioned such that only the engagement of one blocking element at any time in a gap between blocking slides is possible. 
     It is expedient to arrange the at least one blocking slide (or possibly all blocking slides) above the slide slots. This means that the slide slots remain free from blocking elements. On the one hand, this results in a cleaner appearance of the slide slots and therefore of the travel plug adapter as a whole. On the other hand, the partial dipping of plugs and assigned actuation elements into the slide slots can thus be avoided. This partial dipping leads to an unclear plug position, which is often confusing for the user. 
     In addition, this arrangement makes it possible to form the travel plug adapter in a compact manner. In this sense it is also expedient to arrange the at least one blocking slide (or possibly all blocking slides) behind the slide slots. 
     It is also expedient when at least one first blocking slide of a first length and one second blocking slide of a second length are used, wherein the second blocking slide is longer than the first slide. In this way, it is possible to compensate for different distances between the slide slots, and it is also possible to accommodate blocking elements of different thickness or, in respect of individual blocking elements, to particularly effectively prevent the blocking element from dipping into a gap between the blocking slides. 
     The blocking elements can be formed in various expedient ways. The plugs typically have guide elements, for example a supporting bar. The blocking element can be fixedly connected to a guide element of this type or, as appropriate, an element attached to the guide element. By way of example, the blocking element can have the form of a cam or a lug. Here, the blocking element can also be formed in one piece with the corresponding guide element. The blocking element, however, in this case is an element different from the actuation element. 
     It is also expedient to form the blocking elements as separate components, i.e. generally elements which are movable independently of the movement of the guide elements. The blocking elements are preferably also movable separately. By way of example, the blocking elements can be formed as levers, in particular as tiltable levers. The axis of rotation of such tiltable levers can be oriented parallel to the axis of the displacement of the blocking slides on the displacement track. By way of example, it is expedient when the tiltable levers have a cam which can engage in a groove of a guide element of the plugs. 
     It is advantageous when the at least one blocking element (or possibly all blocking elements) are connected to a control lever which allows or blocks the transfer of the at least one blocking element (or possibly all blocking elements) into the open position. The control lever or finger can be embodied as a separate element and can be connected to the blocking element or also can be formed in one piece with the blocking element. By way of example, a U-shaped lever has proven to be of use, of which one lever end has an element or in particular a projection, which can cooperate with the plug or in particular a supporting element of the plug. The other end of the U-shaped lever can then serve as a control lever or finger. 
     The control levers or fingers can engage in a locking mechanism, in particular a blocking slide of a locking mechanism. 
     The plugs may be brought into the usage position with the aid of the actuation sliders. It is advantageous for safe use of the travel plug adapter that the plugs also remain in the usage position even when they are inserted into an outlet against a pressure. In the framework of the present invention, an arresting or locking element may be provided to ensure that the plugs remain in the usage position and to arrest them there. This locking element may arrest at least one plug of the travel plug adapter; the locking element may also usefully arrest a plurality of or all of the plugs in the usage position. 
     It is useful when the locking element is connected to a release button that is provided on the exterior of the housing and is to be actuated in a release direction. Such a release button permits intuitive and safe release of the locking element when a plug is to be moved out of the usage position back into the standby position. This design appears safer and more reliable than those in which certain movements of the actuation slider or even the sliding selector or even the plug itself lead to releasing the plug. So that the release button cannot be actuated inadvertently, it may also be provided with warning indicators or be designed in a warning colour, for instance in red. The release button may be part of the housing, for instance if due to suitable design a part of the housing can be depressed. As a rule it is useful to provide a recess in the housing and to provide the release button in this recess as a part that is independent of the housing. The release button may usefully be arranged opposing the sliding selector and/or the actuation sliders. 
     It is useful when the locking element, if any, is resiliently pre-stressed against the release direction. Resiliently pre-stressing the locking element permits plugs to be reliably snapped into a lock as soon as the plugs are in the usage position. It is also advantageous mechanically when the springs act precisely against the release direction. 
     A useful embodiment of an (optional) locking element is an embodiment in which the locking element has at least one locking leg and this locking leg has a slide surface and a locking projection. An element that is connected to a moved plug may slide on the slide surface. This element may then snap in at the locking projection so that the plug connected to the element is locked. 
     A travel plug adapter is useful in which at least one plug has a sliding projection or is mechanically securely connected to such and the sliding projection runs on the slide surface and can assume a locking position on the locking projection, if any. 
     Also useful is a travel plug adapter in which the locking means has a plurality of locking legs, for instance two, three, or four locking legs. The number of locking legs may be exactly the same as the number of plugs. It may also be useful and sufficient when the number of locking legs is less than the number of plugs. 
     Especially in the latter case it is useful when at least two plugs are each connected to a sliding projection and both sliding projections run on the same locking leg of the locking element. Since the two sliding projections run on the same locking leg, this means that the two sliding projections run on the same slide surface and on the same locking projection on which the two sliding projections can assume a locking position. Because two plugs in the travel plug adapter are not supposed to be moved into the usage position at the same time, the sliding projections alternatively assume this locking position on the locking projection. However, if two sliding projections, for instance two sliding projections of adjacent plugs, share a suitably dimensioned locking leg, the number of locking legs may be reduced and the travel plug adapter may thus be constructed even more compactly. 
    
    
     
       Additional features, but also advantages, of the invention, result from the drawings in the following and the associated description. Features of the invention are described in the figures and associated descriptions in combination. These features may, however, also be included by an inventive subject matter in other combinations. Each disclosed feature should thus also be considered to be disclosed in technically reasonable combinations with other features. Some of the figures are have been slightly simplified and are diagrammatic. 
         FIG. 1  is a perspective representation of an exemplary embodiment of an inventive travel plug adapter; 
         FIG. 2  provides a representation, from a similar perspective, of the exemplary embodiment of the travel plug adapter in which the US plug has been moved to the usage position; 
         FIG. 3  is a perspective representation of the travel plug adapter according to  FIG. 2  in which the underside is visible, 
         FIG. 4  is a corresponding perspective representation of the travel plug from  FIG. 3  in which the Schuko plug has been transferred into the use position, 
         FIG. 5  is a perspective elevation of selected cooperating components of the travel plug, 
         FIG. 6  is a similar perspective elevation of selected cooperating components; 
         FIG. 7  shows, in selected cooperating components, an embodiment of a locking mechanism, 
         FIG. 8  is a perspective elevation of selected cooperating components of another embodiment of the locking mechanism, 
         FIG. 9  illustrates the components from  FIG. 8  in a different perspective 
     
    
    
       FIG. 1  is a perspective representation of an inventive travel plug adapter  10  that is ready for use, but is not yet in the usage position. Instead, all of the plugs are in the standby position, i.e., in the housing. 
     In the following, first the most essential elements of the travel plug adapter  10  shall be described. The travel plug adapter has a housing that consists of an upper housing part  12  and a lower housing part  14 . The upper housing part  12  and the lower housing part  14  together form the main plug housing. Disposed on the top side of the travel adapter plug, and thus in the area of the upper housing part  12 , is the plug receptacle  16 . The latter has a plurality of female connectors  18 . More specifically, these are the female connector pair  18 A for receiving current-conducting UK contact pins, the female connector pair  18 B for receiving current-conducting AU contact pins, the female connector pair  18 C for receiving current-conducting US contact pins, the connector  18 D for receiving a UK grounding pin, and the connector  18 E for receiving a US grounding pin or AU grounding pin. 
     The release button  20  is also provided on the housing side. Said release button serves to lock and release actuation elements. On the housing front side there are provided the first actuation slider  22 , by means of which the US contacts can be slid out, the second actuation slider  24 , by means of which the AU contacts can be slid out, and the third actuation slider  26 , by means of which a Schuko plug can be slid out. 
       FIG. 2  is a perspective representation of the exemplary embodiment of the travel plug adapter according to the invention in which the actuation slider  22  has been transferred into its lower position. The contact pins for the US plug  28  protrude from the housing accordingly. The US plug  28  comprises two current-conducting contact pins (the pins  30 A and  30 B) and also a grounding pin  32 . In the illustrated position the travel plug can be inserted into an outlet according to the US standard. This standard does not require a plug body to be used. The housing underside of the travel plug adapter  10  then lies flush on the flat surface of the plug according to the US standard. 
     In  FIG. 3  the same travel plug is illustrated from a different perspective. Here, it can be clearly seen that the underside  34  is planar. However, a multiplicity of openings  36  and elements are provided on this underside. The openings  36 A and  36 B are provided for current-conducting Schuko contact pins. The openings  36 C and  36 D are provided for current-conducting AU contact pins. The opening  38  is provided for an additional grounding pin. The opening  38  is provided together with the openings  36 A and  36 B in the plug body  40  of the Schuko plug. In addition to this plug body, a securing insert  46  is also provided. 
       FIG. 4  provides a representation, from the same perspective, of the travel plug adapter according to the invention in which the Schuko plug has been moved to the usage position. The third actuation slider  26  has been brought into its lower position, accordingly. The plug body  40  of the Schuko plug protrudes beyond the underside  34  of the housing. The current-conducting contact pins  42 A and  42 B of the Schuko plug in turn protrude from the Schuko plug. In accordance with the standard, grounding contacts  44  are disposed on the sides of the plug body. 
       FIG. 5  is a perspective elevation of selected cooperating components of the travel plug  10 . With the upper housing part removed, it is possible to see into the inside of the plug, i.e. substantially those components that are received by the lower housing part  14  can be seen. It should also be noted that not all components necessary for the function of the plug are illustrated. For the sake of clarity, a selection has been made. 
     The plug body  40  of the Schuko plug can be seen. In this, there are provided the openings  36 A and  36 B for the current-conducting contact pins of the Schuko plug. The opening  36 E, which is provided for a grounding contact pin, can also be seen. In this representation a further opening can also be seen—the opening  56  for the grounding pin of the AU plug. 
     The current-conducting contact pins  30 A and  30 B for the US plug are also illustrated. These are in their standby position, i.e. are retracted into the housing. The first actuation slider  22  is in the upper position, accordingly. The actuation slider  22  can be held in this position by the locking mechanism  48 . 
     The actuation slider  22  moves the supporting bar  50 . The contact pins  30 A and  30 B are fixed to this supporting bar  50 . The supporting bar  50  travels downward accordingly as the first actuation slider  22  is displaced in the direction of the base of the housing. In so doing, the contact pins  30 A and  30 B are guided in the plug body  40  of the Schuko plug. The Schuko plug thus provides a guide for contact pins of another standard. 
       FIG. 6  is a similar perspective representation of a similar selection of cooperating components. Here, as key difference from  FIG. 5 , the supporting bar  52  for the AU plug can also be seen. The supporting bar  52  is connected to the actuation slider  24 . The supporting bar  52  has three bar ends, the bar ends  54 A,  54 B and  54 C, which merge in the region  54 . The bar ends  54 A and  54 B support the current-conducting contacts of the AU plug. They guide these contacts mechanically from the (shown) standby position into the usage position. The bar end  54 C guides the AU grounding pin. The grounding pin is thus transferred from the (shown) standby position into the usage position through the opening  56  visible in  FIG. 5 . 
     An arrangement in which the current-conducting pins are guided outside the plug housing  40  of the Schuko plug is thus selected for the AU plug, in contrast to the grounding pin within the plug housing  40  of the Schuko plug. By contrast, the current-conducting contact pins for the US plug are guided within the plug body  40  of the Schuko plug. Both solutions allow an advantageous and space-saving arrangement. Different solutions can be selected for different plugs. 
       FIG. 7  is a perspective elevation of selected cooperating components of the travel plug  10 . A first supporting frame  60 , which as guide element supports and guides various contact pins (not denoted in greater detail), is illustrated. A second supporting frame, which similarly guides a plurality of contact pins, is also illustrated. A third supporting frame  64  is also illustrated. The supporting frames  60  and  62  are illustrated in an upper position, i.e. in a position which corresponds to their standby position. The third supporting frame  64  is illustrated in a position displaced downwardly, which corresponds to the usage position. The supporting frame  60  is connected to the actuation element  66 . The rest of the supporting frames are connected similarly to actuation elements, however these are not visible from this perspective. In addition, the supporting frames are connected to head pieces, specifically the supporting frame  60  is connected to the head piece  68 A, the supporting frame  62  is connected to the head piece  68 B, and the supporting frame  64  is connected to the head piece  68 C. 
     Three blocking slides are also provided, i.e. the blocking slides  70 A,  70 B, and  70 C. These blocking slides run on the displacement track  72 . This displacement track  72  extends between a first end  74  and a second end  76 . At the two ends, delimitation elements are provided, which delimit the running of the blocking slides at both ends of the displacement track  72 . In the first end piece  74 , a coil spring can also be provided (not shown), which exerts pressure on the blocking slide  70 C so that this is pre-stressed towards the second end piece  76  of the displacement track  72 . The pressure is transferred from the blocking slide  70 C to the blocking slides  70 B and  70 A, such that all blocking slides are resiliently pre-stressed towards the second end piece  76  of the displacement track  72 . 
     The usable length of the displacement track  72 , i.e. the length between the first end piece  74  and the second end piece  76 , is slightly longer than the sum of the lengths of the blocking slides  70 A,  70 B and  70 C. A gap  78  can thus be formed between the blocking slides  70 . A head part of a supporting frame can engage in this gap. In the plug position of  FIG. 7 , the head part  68 C engages in the gap  78  between the blocking slide  70 B and the blocking slide  70 C. The head part  68 C can be moved through the gap, such that it reaches the shown lower position, which corresponds to the usage position of the plug assigned to the supporting frame  64 . In this position, however, the head piece  68 C fully fills out the available length on the displacement track  72  together with the blocking slides  70 A,  70 B and  70 C. Consequently, there is no longer a gap or any play allowing the head parts  68 A and  68 B to enter into engagement with the blocking slides—in other words there is no longer any space for a second gap, which would allow the passage of another head part. 
     In this way, a locking mechanism  58  can thus be created, which ensures that just one plug at any time is transferred into its usage position. The blocking slides can be provided at the edges with a bevel  80 . This allows the easy passage of a head piece  68 . Correspondingly, the head pieces  68  can have a tapered point in the form of a cutting end  82  at their lower edge. This also facilitates the insertion of the head piece  68  into a gap between the blocking slides  80 . However, the usable length of the displacement track  72  should in any case be dimensioned such that, in spite of such insertion and passage aids, not more than one head piece  68  can be transferred into the usage position. On the whole, a simple and precisely functioning mechanism can thus be created, which makes the additional provision of a sliding selector superfluous. The mechanism also ensures that the actuation elements each assume a clear standby position or usage position. The user is never in doubt as to which state a plug is currently in. Travel plug adapters from the prior art, by contrast, sometimes allow a partial transfer of plugs in the direction of the standby position, for example when blockers only engage late in the slide slots. 
       FIG. 8  shows a perspective elevation of selected components, on the basis of which an embodiment of a locking mechanism that is expedient within the scope of the present invention can be identified. Three actuation elements are illustrated in the form of a first actuation slider  84  for a US plug, in the form of a second actuation slider  86  for a UK plug, and in the form of a third actuation slider  88  for an AU plug. Of course, the illustrated locking mechanism  90  can also cooperate with other plugs, for example the arrangement shown in  FIG. 1 . The locking mechanism  90  in turn comprises a displacement track  92  as an element. This displacement track  92  extends between the first end piece  94  and the second end piece  96 . A coil spring  98  is provided bearing against the first end piece  94  and is suitable for pre-stressing the various blocking slides towards the second end piece  96  of the displacement track  92  in a resilient manner. 
     The coil spring  98  is arranged in the first blocking slide  100 A. It also acts (conveyed via this slide) on the second blocking slide  100 B and on the adjacent third blocking slide  100 C. The blocking slides are each provided with guide cheeks, i.e. the guide cheeks  102 A,  102 B and  102 C. Bevels are also provided at the ends of the blocking slides, i.e. the bevels  104 A,  104 B, and  104 C. 
     Rocker levers are arranged above the displacement track  92 . Each actuation element and thus plug is assigned its own rocker lever. The rocker lever  106 A is assigned to the actuation element  84 , the rocker lever  106 B is assigned to the actuation element  86 , and the rocker lever  106 C is assigned to the actuation element  88 . The rocker levers rotate about an axis of rotation (not illustrated) below the displacement track  92 . The axes of rotation run substantially parallel to the displacement track  92 . Each rocker lever has a control finger  108  formed in one part therewith. For the sake of clarity, this has only been indicated in greater detail for the rocker lever  106 C. A blocking cam  110  is provided opposite the control finger  108 . The blocking cam can enter into engagement with the associated actuation element and can fix this in the standby position. The mechanics effective here will be explained in greater detail in conjunction with the next drawing. 
     What can be seen from this representation is that the rocker lever  106 C is in a lower position. In this position, the control finger  108  is directly above the displacement track  92 . In this position, the control finger can pass only when there is a suitable gap between the blocking slide  100 C and the second end piece  96 . The control finger  108  engages in this gap. The guide cheek  102 C and the bevel  104 C ensure that, as the rocker lever  106 C moves, the control finger  108  can dip reliably into this gap. The gap is dimensioned such that, once the control finger has dipped into said gap, a displacement of the blocking slides  100 A,  100 B or  100 C is no longer possible. The same is also true similarly for the control fingers of the other rocker levers. 
     When the rocker lever  106 C is transferred into its upper position, which corresponds to the standby position of the actuation slider  88 , in which the control finger  108  is disposed above the blocking slide  100 C, there is space to displace all three blocking slides. Accordingly, the rocker lever  106 B, which is assigned to the actuation slider  86 , could then be transferred into a lower position. Here, its control lever, guided by the guide cheek  102 B and the bevel  104 B, would slide the blocking slide  110 C away to the right towards the second end piece  96 . However, this would be possible due to the fact that a gap is available there on account of the corresponding position of the rocker lever  106 C. 
       FIG. 9  shows, from a different perspective, the selected components illustrated in  FIG. 8  of an embodiment and again the actuation sliders  84 ,  86  and  88 . The actuation sliders  84  and  86  and the corresponding plugs are in the standby position. The actuation slider  88  and the corresponding plugs are in the usage position. Only the parts essential for describing the operating principle of the rocker lever have been indicated. For the rocker lever  106 C, it can be seen that the blocking cam  110 C can engage with a corresponding engagement part  112 C on the actuation slider  88 . Such an engagement part can be embodied generally expediently as a groove. A counter cam  114 C is additionally provided on the actuation slider. When the actuation slider is transferred into its upper position corresponding to the standby position, the counter cam  114 C presses against the pressure surface  116 C on the rocker lever  106 C. This causes the rocker lever  106 C to be moved back into its upper position. Here, the blocking cam  110 C engages with the engagement part  112 C. A form-fitting connection is thus established, which holds the actuation slider  88  in the upper position. The rocker lever could also be spring-loaded in order to securely hold the position independently of the position of a blocking slide. However, as soon as the blocking slide  100 C is displaced and the position of the rocker lever  106 C is fixed via the control finger  108 , the actuation slider  88  is held securely and fixedly in its upper position. 
     The securing of the upper position can be clearly seen for the actuation slider  86 . Here, the blocking cam  1108  is fixedly connected to the engagement part  112 B of the actuation slider  86 . In addition, the counter cam  114 B is engaged with the rocker lever. The blocking slide  100 C prevents the control lever  108 B and therefore the rocker lever  106 B as a whole from being able to be moved downwardly. 
     In this perspective illustration it can also be clearly seen that the fixing in the region of the blocking cam  110 C can securely fix all elements of the plug. Only when the rocker lever releases the engagement part  112  can the supporting bar  118  for the AU plug be moved downwardly. This supporting bar guides both the current-conducting contacts  120 A and  120 B and also the grounding contact  122  reliably downwardly and upwardly again. 
     In the manner described generally, and described more specifically in the drawings, a travel adapter may be produced that is very comfortable to operate, but in which almost no operating errors are to be expected. Interestingly, the travel adapter is nevertheless inexpensive to produce and may also be produced inexpensively and reliably even if greater fault tolerances must be permitted during mass production. 
     REFERENCE LIST 
     
         
           10  Travel adapter/travel plug adapter 
           12  Upper housing part 
           14  Lower housing part 
           16  Plug receptacle 
           18  Female connector 
           18 A UK female connector pair 
           18 B AUS female connector pair 
           18 C US female connector pair 
           18 D Female connector for UK grounding pin 
           18 E US grounding pin 
           20  Release button 
           22  First actuation slider 
           24  Second actuation slider 
           26  Third actuation slider 
           28  US plug 
           30  Current-conducting contact pins (US plug) 
           32  Grounding pin (US plug) 
           34  Plug body (Schuko plug) 
           36  Openings 
           36 A Opening of current-conducting contacts (Schuko) 
           36 B Opening of current-conducting contacts (Schuko) 
           36 C Opening of current-conducting contacts (US) 
           36 D Opening of current-conducting contacts (US) 
           36 E Opening of further grounding contact 
           38  Schuko plug 
           40  Schuko plug body 
           42  Current-conducting contacts of Schuko plug 
           44  Grounding contact of Schuko plug 
           46  Fuse compartment 
           48  Locking mechanism 
           50  Supporting bar US 
           52  Opening of grounding pin 
           54  Supporting bar AU 
           56  Supporting bar ends AU 
           58  Locking mechanism 
           60  First supporting frame—guide element 
           62  Second supporting frame—guide element 
           64  Third supporting frame—guide element 
           66  Actuation element 
           68  Head piece 
           70  Blocking slide 
           72  Displacement track 
           74  First end piece of displacement track 
           76  Second end piece of displacement track 
           78  Gap 
           80  Bevel on blocking slide 
           82  Cutting end 
           84  Actuation element US 
           86  Actuation element UK 
           88  Actuation element AU 
           90  Locking mechanism 
           92  Displacement track 
           94  First end piece 
           96  Second end piece 
           98  Coil spring 
           100  Blocking slide 
           102  Guide cheek 
           104  Bevel 
           106  Rocker lever 
           108  Control finger 
           110  Blocking cam 
           112  Blocking cam engagement part 
           114  Counter cam 
           116  Pressure surface 
           118  Supporting bar AU 
           120  Current-conducting contacts AU 
           122  Grounding contact AU