Patent Publication Number: US-7896685-B2

Title: Installation switching device

Description:
This is a U.S. National Phase application under 35 U.S.C. §371 of International Application No. PCT/EP2007/008585, filed on Oct. 4, 2007, which claims priority to German Applications No. DE 10 2006 047 254.3, filed on Oct. 6, 2006; DE 10 2007 043 801.1, filed on Sep. 13, 2007; DE 10 2007 044 069.5, filed on Sep. 14, 2007; and DE 10 2007 044 262.0, filed on Sep. 17, 2007. The International Application was published in German on Apr. 17, 2008 as WO 2008/043466. 
     The invention relates to an installation switching device comprising a housing and with a screwless terminal connection with a clamping spring for the connection of connecting conductors. 
     BACKGROUND 
     A generic installation switching device can be, for example, a circuit breaker, a fault-current circuit breaker, a motor protection switch or the like. It comprises within its housing at least one contact point comprising at least one fixed and one moving contact member via which a current path leading from an input terminal to an output terminal can be opened and closed. The contact point is generally actuated by a switching mechanism with latching point. A generic installation switching device can also comprise tripping devices, for example a thermal trip or an instantaneous tripping magnet which, when a short circuit or fault current occurs in the current path, act on the contact point or the switching mechanism, respectively, so that the contact point is opened. 
     Apart from screw terminals, screwless clamping connections are also used for the connection to external connecting conductors in generic installation switching devices. In this context, plug-in terminals or spring-pull terminals can be used as clamping elements. In principle, these can considerably simplify the connection of connecting conductors but known installation switching devices with screwless terminal connections are still subject to considerable restrictions in use today. 
     From EP 1 432 077, a generic installation switching device with a screwless terminal connection is known in which the terminal connection space is open towards the narrow side of the housing and is covered with a cover part corresponding to the housing width in its width. The cover part is clipped to the housing on its narrow side. At the terminal connection according to EP 1 432 077, rigid conductors can be inserted without tools but the insertion of flexible conductors and the removal of the conductors from the terminal connection require the use of a tool. 
     From EP 1 089 379, a generic installation switching device comprising a clamping spring housing moulded separately onto the housing is known in which the conductors can be inserted and extracted without use of a tool. Due to the clamping spring housing being moulded on separately, the construction is very elaborate however and is additionally restricted to the use of spring-pull terminals. 
     EP 1 124 286 shows a generic installation switching device with plug-in terminals which, however, are accommodated on a separate terminal block, wherein the terminal block must be subsequently plugged onto the switching device. In this respect, the solution demonstrated here is very elaborate and requires additional parts for plugging on to the installation switching device so that no standardized uniform housings can be used. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention is to provide a generic installation switching device in which the terminal connection is arranged in a simple and cost-effective manner in such a manner that the toolless insertion and removal of connecting lines becomes possible. 
     According to the invention, the terminal connection space is laterally limited by the wide housing sides and is open at least to the front face, wherein the opening of the terminal connection space can be covered by a terminal cover part which is swivelably connected with the housing. The terminal cover part has a terminal face with a number of terminal openings corresponding to the number of connecting conductors to be connected and guide means, moulded onto each terminal opening, for the connecting conductors. 
     According to an advantageous embodiment, spring actuating means are moulded onto the cover part and are arranged in such a manner that, when the cover part is swivelled against the clamping spring, they load the latter so as to open it. 
     The terminal connection of an installation switching device according to the invention comprises very few components, namely the clamping spring, a conductor bar with a clamping edge against which the clamping spring clamps the connecting conductor to be connected, and the cover part. It can, therefore, be produced in a very simple and cost effective manner. 
     The cover part is arranged in such a manner that it realizes a number of functions in one component:
         The guide means moulded onto the cover part at each terminal opening provide for the guidance of the connecting conductor towards the connecting terminal at the required insertion angle. Neither the conductor bar nor the clamping spring itself need to exhibit further guide means for guiding the connecting conductor.   A number of connecting conductors are inserted through a number of terminal openings and are held apart at the same time. Thus, an individual insertion of each individual conductor end is possible even with a number of conductor ends to be clamped on, without further measures for keeping the individual conductors apart being required at the clamping spring or the conductor bar.   Due to the spring actuating means moulded onto the cover part according to another advantageous embodiment, the cover part can become the opening tool for the clamping spring at the same time. A separate actuating tool, for example a screwdriver, for opening the clamping spring is no longer required. This greatly simplifies the insertion and removal of connecting conductors.       

     According to an advantageous embodiment of the invention, the terminal cover part is resiliently loaded by the clamping spring in opposition to the direction of insertion of the external connecting conductor, and can be pressed against the clamping spring. In this arrangement, the cover part can be particularly advantageously resiliently loaded by the clamping spring against a projection, used as stop, of the housing wall. The terminal cover part is thus held in a defined initial position due to the resilient loading of the clamping spring. The initial position is in this case the closing position of the clamping spring. 
     According to a particularly advantageous embodiment of the invention, the spring actuating means are formed by the guide means, moulded onto each terminal opening, for the connecting conductors. This can be implemented, for example, by the guide means for the connecting conductors being tube-like hollow bodies pointing from the inside of the cover part to the clamping spring and forming a lead-in conduit for the connecting conductors. The terminal cover part can then be constructed in a particularly simple manner and can be produced, for example, as cost-effective injection moulding part. 
     For the pressure actuation of the terminal cover part, it can be provided that the terminal cover part has a pressure area which is accessible from the outside and can be manually operated. 
     To ensure access for a voltage tester to the terminal connection in a simple manner in the operating state, that is to say after completed assembly of the installation switching device, the terminal cover part can have a test opening for electrically contacting the terminal connection. 
     With respect to the spatial arrangement of the terminal face with respect to the front face of the housing and of the guide means with respect to the terminal face, a possible embodiment of the invention provides that the terminal face of the terminal cover part extends approximately in parallel with the rear face and the guide means are inclined with respect to the terminal face of the terminal cover part. The angle of inclination for the guide means must be selected in accordance with the principle that the connecting conductors remain easily accessible during the series installation of an installation switching device according to the invention, for example in a distribution box, and connecting conductors are not bent away towards the top too much. 
     In this respect, a further advantageous embodiment provides that the terminal face of the terminal cover part is inclined with respect to the rear face and the guidance conduits extend approximately perpendicularly to the terminal face. In this embodiment, the angle of inclination at which the connecting conductors are inserted relative to the spring terminal is determined by the angle of inclination of the guidance conduits. 
     Naturally, a combination of the two possibilities demonstrated above would also be conceivable in which both the terminal face of the terminal cover part is inclined with respect to the rear face and the guidance conduits are inclined with respect to the terminal face. 
     To additionally provide for the actuation of the spring terminal by an external tool on demand, for example for reasons of redundancy, according to a further embodiment of the installation switching device according to the invention the terminal cover part can have an access opening for an actuating tool. It is then possible to bring the clamping spring into its opening position through this access opening by means of the actuating tool, for example a screwdriver. 
     According to an advantageous embodiment, a closing part is coupled swivelably with the free end, pointing towards the front face, of a first part-body of the terminal cover part, which covers the terminal connection space at the front face in collaboration with a housing-fixed front face end, the closing part at least partially overlapping the housing-fixed front face end on actuation of the terminal cover part. 
     The closing part and the housing-fixed part of the front face together form the front face. Supplementing the housing-fixed part, the closing part thus acts as part of the front face at the terminal cover part side. 
     According to a particularly advantageous embodiment, the closing part is constructed to be plate-shaped. It can be advantageously produced in the same injection moulding process as the terminal cover part. 
     An embodiment in which the closing part is coupled to the terminal cover part by means of a hinge, for example a film hinge, is particularly very advantageous. Such a film hinge can be produced very advantageously by injection moulding. 
     A further, very advantageous embodiment of the invention is characterized by the fact that the closing part is guided displaceably in a housing-fixed rocker-like guide in parallel with the front face via laterally protruding guide pins. The closing part is then carried overlapping the part at the housing side of the front face in a displaceable manner As a result, it can be swivelled behind the part at the housing side of the rear part, and displaced, on actuation of the terminal cover part. This ensures tight covering of the terminal receiving space towards the front face with simultaneous mobility of the terminal cover part and mechanical stability of the rear face. 
     By attaching the hinge to the closing part, the latter can move in a space-saving manner in parallel with the front face in a rocker-like guide. 
     A development of the invention which is also very advantageous is characterized by the fact that the terminal cover part carries, following the terminal face, a spacing area which forms the closure at the terminal cover part side of the terminal receiving space in the area of the narrow side, wherein the closing part is coupled swivelably at the end of the spacing area pointing towards the front face. As a result, it is possible to place the terminal face into a part of the narrow side wall of the switching device which is closer to the mounting side if this is required due to a predetermined arrangement of the connecting terminals in the interior of the switching device close to the mounting side. 
     According to a particularly advantageous development of this embodiment, the spacing area is constructed to be rigid. This provides for a transmission of force to the spring of the connecting terminal also by actuation of the terminal cover part over the spacing area. This is advantageous if the pressure area of the terminal cover part, due to the position of the connecting terminal, is now only accessible with difficulty by an operating person due to the position of the connecting terminal very close to the mounting side of the switching device in the installed position of the switching device, for example in an installation distributor. In an area which is not covered by a connecting conductor, the spacing area can thus be used as second pressure area for actuating the spring. 
     In a particularly advantageous further embodiment of the invention, the spacing area carries an access opening for an actuating tool. The connecting terminal can thus be operated either manually in or also by means of a tool via the terminal cover part. 
     According to a further, very advantageous embodiment of the invention, the closing part consists, at least in the area of the coupling with the first part-body, of a material which has different mechanical properties than the first part-body of the terminal cover part. 
     Here, too, the closing part covers the terminal connection space at the front face in collaboration with a housing-fixed front face end, the closing part at least partially overlapping the housing-fixed front face end on actuation of the terminal cover part. 
     The closing part and the housing-fixed part of the front face thus together form the front face. As a supplement to the housing-fixed part, the closing part thus acts as part at the terminal cover part side of the front face. 
     In this arrangement, an embodiment is particularly advantageous in which the hinge and the closing part consist in the area of the hinge of a material which has different mechanical properties than the first part-body of the terminal cover part. 
     Due to the fact that the closing part consists, at least in the area of the coupling with the first part-body of the terminal cover part, of a material having other mechanical properties than the latter, the spring-elastic characteristics of the closing part and its coupling with the first part-body can be specified independently of those of the first part-body of the terminal cover part and optimized for the application. This is of advantage especially if different, in some cases even opposite mechanical demands are made on the first part-body of the terminal cover part than on the closing part. 
     This can be the case if the terminal cover part, with an actuation, that is to say a swivelling into the interior of the switching device, simultaneously actuates the clamping spring in a manner so as to open it in opposition to its restoring spring force. 
     This can be effected, for example, by spring actuating means moulded onto the terminal cover part in a suitable position, which act on the clamping spring during a swivelling of the terminal cover part. 
     In this case, the first part-body of the terminal cover part must have a high stiffness so that the force for opening the clamping spring can be transferred without deformation of the terminal cover part. 
     However, the closing part should be flexible, but at least coupled flexibly to the first part-body of the terminal cover part so that it can slide in a space-saving manner behind the housing-fixed front face end in the rocker-like guides during the swivelling of the terminal cover part. 
     When the terminal cover part is swivelled into the device interior, the angle between the closing part and the first part-body of the terminal cover part is forced to change. 
     This is because the closing part should extend as parallel as possible to the housing-fixed front face end. Yet the angle between the first part-body of the terminal cover part and the housing-fixed front face end changes when the terminal cover part is swivelled. A mobility of the closing part with respect to the first part-body of the terminal cover part, which can only be achieved by a flexibility of the material at this point, is therefore required at the coupling point. 
     According to a particularly advantageous development of the invention, the spacing area is constructed to be rigid and the closing part is constructed from a soft material, which is softer than the spacing area, at least in the area of the coupling with the spacing area. 
     This meets the two contradictory requirements for different part-bodies of the terminal cover part. A single component, the terminal cover part, has different material properties in different areas. Due to the stiff part-area, a force can be transmitted to the spring of the connecting terminal also by actuating the terminal cover part over the spacing area. The closing part, the second part-area, however, can be bent away easily and shifted in parallel with the front faces and behind these. 
     In a particularly advantageous embodiment of the invention, the terminal cover part, with the closing part coupled thereto, is produced in a two-component injection moulding process. In this process, materials having different mechanical properties, that is to say, for example, hard and soft plastics, can be joined during the injection moulding. 
     With respect to an advantageous embodiment of the terminal connection, an installation switching device according to the invention has a clamping spring acting as compression spring on the conductor end, for clamping the conductor end at an abutment, wherein the terminal connection comprises a conductor bar with a connecting end and an adjoining discharge area. The conductor bar has at the connecting end a window-like opening with a support edge, and a clamping edge opposite the support edge, at the transition of the connecting end into the discharge area. The clamping spring also has a support leg by means of which it is supported at the support edge of the conductor bar. An arc piece adjoins the support leg and is adjoined by a clamping leg so that the conductor end can be clamped tight between the clamping leg and the clamping edge as abutment. The conductor end can be inserted into the window-like opening from the side of the arc piece. 
     According to an advantageous embodiment of the invention, the arc piece is adjoined by a first part-clamping leg which changes into a second part-clamping leg, bent away from the first part-clamping leg, at a bending edge so that the first and the second part-clamping leg assume an obtuse angle with one another, the opening of which points in the direction of insertion of the connecting conductor. 
     The obtuse angle between the first and the second part-clamping leg provides the advantage that the point of attack can be placed in the vicinity of the spring actuating means in the vicinity of the bending edges. As a result, the resting point of the spring actuating means can have a greater distance from the point of rotation of the clamping leg at the arc piece without the maximum terminal opening, which can be achieved as a result, becoming smaller and without the spring actuating means being in the way of a connecting conductor having a large cross section. However, a greater distance between the resting point and the point of rotation means a more advantageous lever ratio and thus a lower actuating force for the user. 
     A preferred embodiment is characterized by the fact that the conductor bar approximately has a U-shape, the connecting end forming the one U-leg and the discharge area being formed by the crossbar and the other U-leg. In this arrangement, an upward bend for attaching further current conductors which lead into the interior of the installation switching device can be provided at the free end of the other U-leg. 
     According to a further embodiment, a discharge bar can also be mounted onto the free end of the other U-leg. The discharge bar can extend approximately perpendicularly to the other U-leg and the side of the connecting end opposite the clamping edge can be supported at the discharge bar. 
     A further advantage of an installation switching device according to the invention lies in the fact that the discharge area of the conductor bar can be used for electrical contacting during the calibration of the thermobimetal. In previously known installation switching devices, the contact point for the calibration of the thermobimetal is arranged at another point outside the access area of the terminal connection and is not accessible via the terminal connection. Since the thermobimetal can only be calibrated in the completely assembled state, the separate access openings to the calibration contacts must be covered by additional cover parts after the calibration in known installation switching devices. 
     This is not necessary in an installation switching device according to the invention. Compared with the installation switching devices known in the prior art, this saves both assembly parts—namely the additional cover parts—and production steps in the assembly so that the resultant simplification of assembly results in a further advantage of the installation switching device according to the invention. 
     An installation switching device according to the invention can be completely assembled apart from the terminal cover part. The calibration of the thermobimetal is then performed—by means of electrical contacting through the opening of the terminal connection—by using the discharge area of the conductor bar as calibration contact. After completed calibration, the terminal cover part is put in place and the installation switching device is thus completed. A separate cover part for the calibration opening is no longer required. 
     A further advantage is given by the fact that, due to the arrangement according to the invention, the terminal connection of an installation switching device according to the invention is constructed in such a manner that it only has a low electrical resistance even with very narrow external dimensions. This is achieved by the fact that the conductor bar has a uniform width in the discharge area between the clamping edge and the point at which a further current conductor is attached which leads into the interior of the installation switching device. This makes it possible to build up installation switching devices according to the invention also in half standard module width. 
     According to DIN 43 880, a module a is defined for the module width of installation switching devices. According to this standard, the module width is an integral or half-integral multiple of 17.5 mm, more precisely: a=n×(17.5 mm+0.5 mm), n=0.5; 1.5; 1.5; 2.0, . . . . 
     An installation switching device having half a standard module width thus has a module width of 9 mm. 
     In a further embodiment, the clamping leg of the clamping spring can be longitudinally slotted for facilitating the clamping-on of two connecting conductors, so that two part-springs are produced which are closely next to one another and can be clamped independently of one another. Due to the fact that the two part-springs are close together, that is to say without having a separating, relatively large intermediate space or an intermediate web between them which is approximately in the centre, a further contribution is made towards a narrow construction of the terminal connection so that the terminal connection according to the invention can be installed in an installation switching device having only half a standard module width. 
     Further advantageous embodiments and improvements of the invention and further advantages can be found in the subclaims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention and further advantageous embodiments and improvements of the invention will be explained in greater detail and described with reference to the drawings, in which 5 illustrative embodiments of the invention are shown. 
       In the drawings: 
         FIG. 1 : shows a diagrammatic partial sectional view of an installation switching device according to the invention in a first embodiment, 
         FIG. 2 : shows a diagrammatic part-view of the installation switching device according to  FIG. 1 , 
         FIG. 3   a : shows a diagrammatic view of the spring force terminal of the installation switching device according to  FIG. 1  according to the invention, in the closed state, 
         FIG. 3   b : shows a diagrammatic view of the spring force terminal of the installation switching device according to the invention according to  FIG. 1 , in the opened state, 
         FIG. 4   a : shows a diagrammatic part-view of an installation switching device according to the invention in a second embodiment, 
         FIG. 4   b : shows the terminal cover part for use with the installation switching device according to the invention according to  FIG. 4   a,    
         FIG. 5 : shows a diagrammatic part-view of an installation switching device according to the invention in a third embodiment, 
         FIG. 6 : shows a diagrammatic view of a variation of the spring force terminal according to  FIG. 3   a,    
         FIG. 7 : shows a diagrammatic partial sectional view of an installation switching device according to the invention with a terminal cover part at which a closing part is coupled via a hinge, with the closed terminal, and 
         FIG. 8 : shows a diagrammatic part-view of the installation switching device according to  FIG. 7 , with the terminal opened in the operated position. 
     
    
    
     DETAILED DESCRIPTION 
     In the figures, identical or identically acting components or elements are in each case provided with identical reference numbers even if they are arranged in slightly modified form in different variants of the embodiment. 
     Thus,  FIG. 1  shows a partial sectional view of the terminal connection space  18  of an installation switching device  1  according to the invention with the housing opened.  FIG. 2  shows a corresponding part-view with the housing  3  closed. 
     The installation switching device  1  has an insulating housing  3  formed from two housing parts  2  joined together along a partition line  2   a , with a front face  4 , a rear face  5 , a mounting or connecting side  6 , a front narrow side  7 , a rear narrow side  8  and two wide sides  9 , only one of which is shown in the view according to  FIG. 2 . 
     The terminal connection space  18  is limited laterally, that is to say towards the wide side, by the housing wide sides  9  of the insulating housing  3 . Towards the front face  4 , an opening  20  of the terminal connection space  18  is formed by an opening in the rear face of the housing part  2 , through which the terminal connection  10 , fixed in position in the terminal connection space  18 , is accessible for the connection of connecting conductors  14 . Due to a further opening at the rear narrow side  8  of the housing part  2 , the opening  20  of the terminal connection space  18  extends past the contact edges between the rear narrow side  8  and the rear face  5  into the rear narrow side  8 . This has the advantage that increased flexibility is given for the direction of connection of the connecting conductor  14 . 
     The terminal connection  10  described in the text which follows is a so-called plug-in terminal connection. It comprises a conductor bar  102  and a clamping spring  12 . The terminal connection  10  rests on a projection  110  formed on the inside of the wide side  9  and is there fixed in position in the terminal connection space  18  in a manner known per se by means of webs  104  and pins  106 ,  108 . The terminal connection  10  fixed in position in the terminal connection space  18  is thus located between the rear narrow side  8  and the rear face  5  in the area of the contact edge. 
     The construction of the terminal connection  10  is shown in detail in  FIGS. 3   a  and  3   b . The conductor bar  102  comprises a connecting end  112  and an adjoining discharge area  114 . At the connecting end  112 , it has a window-like opening  116  with a support edge  118  and a clamping edge  120  opposite the support edge  118 . The clamping edge  120  is located at the transition of the connecting end  112  into the discharge area  114 . 
     The clamping spring  12  has a support leg  212  with which it is supported on the support edge  118  of the conductor bar  102 . The support can be effected in such a manner that the support leg  212  has at its free end an upward bend with which it partially encloses the support edge  118  for the purpose of supporting. 
     The support leg  212  is adjoined by an arc piece  214  which is adjoined by a clamping leg  216 . The conductor end  16  of a connecting conductor  14  is inserted into the window-like opening  116  from the side of the arc piece  214  and can be clamped tight between the clamping leg  216  and the clamping edge  120  acting as abutment. In this arrangement, the free end of the clamping leg  216  passes through the window-like opening  116 . 
     The clamping leg  216  of the clamping spring  12  is longitudinally slotted along a slot  2181  so that two part-springs  13   a ,  13   b  are produced which can be clamped independently of one another and by means of which two connecting conductors can be clamped on independently of one another. The slot  2181  is very narrow and does not produce a spatial separation of the two part-springs  13   a ,  13   b . The only result is that they can be bent independently of one another due to the slot. Otherwise, the two part-springs  13   a ,  13   b  are close together at their narrow longitudinal sides, however, so that no additional space is needed between them. 
     The conductor bar  102  has an approximately U-shaped basic form, the connecting end  112  forming the first U-leg and the discharge area  114  being formed by a crossbar  220  and the second U-leg  222 . At the free end of the second U-leg  222 , an upward bend  224  is attached. At this upward bend  224 , further connecting conductors can be attached by means of which the terminal connection  10  is connected to other assemblies within the switching device housing such as, for example, the tripping assemblies. In particular, the connecting conductors can be welded or hard-soldered to this upward bend, and screwing-on is also possible. 
     In an alternative embodiment of a terminal connection which is shown in  FIG. 6 , the upward bend is elongated at the free end of the second U-leg  222  to form a discharge bar  226 . The discharge bar  226  is thus positively joined to the second U-leg  222 ; it points approximately perpendicularly from the latter in the direction of the window-like opening  116  and protrudes above it. At the free end of the discharge bar  226 , a further upward bend  228  is located to which further connecting conductors can be welded or riveted again. The upward bend can also, however, be used directly as terminal connection within the switching device. Overall, the conductor bar  102  according to the present embodiment is provided with an external contour which resembles the small letter “b”. The connecting end  112  of the conductor bar  102  is supported against the discharge bar  226 . From the conductor bar  102  and the discharge bar  226 , a closed terminal frame is thus produced which is stable in itself. This increases the mechanical stability of the terminal connection  10 . 
     This is because, as a result, the advantage is produced that the forces acting on the terminal connection  10  during the insertion and detachment of the connecting conductor are absorbed by it as a closed system and thus forces acting on other elements of the installation switching device such as, for example, the housing, are reduced. 
     The conductor bar  102  can be produced in very large numbers inexpensively and simply and in a wide variety of shapes, for example as punched bent part. 
     Now back to  FIGS. 1 and 2 . The opening  20  of the terminal connection space  18  is covered by a terminal cover part  22  swivelably connected with the housing  3 . The terminal cover part  22  is constructed to be approximately L-shaped, the two legs being formed by cover plates located at an angle to one another. 
     The first cover plate covers the terminal connection space  18  towards the rear face  5  and has a terminal face  24 , with two terminal openings  26 , wherein one connecting conductor  14  can be connected through each of the terminal openings  26 . 
     The second cover plate covers the terminal connection space  18  towards the rear narrow side  8  and has a pressure area  230  which is accessible from the outside and which can be manually operated. At its free edge, the second cover plate has a half-open, tube-like cavity with which it is supported rotatably in a hinge pin  232  connected with the wide side  9  of the housing  3 . The terminal cover part  22  can thus be swivelled around the free edge of the second cover plate in the direction of the clamping spring by means of pressure on the pressure area  230 . Falling-out of the cover part  22  is prevented by a projection  234  at the housing wall, which is used as a stop. In the example of  FIG. 1 , one half of the projection  234  is in each case attached to each of the two housing parts  2  at their contact edge. 
     At the first cover plate of the cover part  22 , tube-like hollow bodies  28  forming a lead-in conduit are attached at each of the terminal openings  26 , aligned towards the clamping spring  12 . These are used at the same time as guide means for the connecting conductor  14  to be inserted and as spring actuating means  30 . When the cover part  22  is swivelled in the direction of the clamping spring  12  around the hinge pin  232  by pressure on the pressure area  230 , the hollow bodies  28  press the clamping leg  216  in the clamping spring  12  away from the clamping edge  120  of the conductor bar  102  so that space for inserting the stripped connecting conductor end  16  of the connecting conductor  14  is produced between the clamping edge  120  and the clamping leg  216 .  FIG. 1  shows this condition. 
     If, after the insertion of the connecting conductor end, the pressure area  230  of the cover part  22  is released again, the clamping leg  216  of the clamping spring  12 , due to its spring force, again presses the cover part  22  outwards over the hollow bodies  28  and, at the same time, clamps the end  16  of the connecting conductor  14  against the clamping edge  120  of the window-like opening  116 . 
     In the embodiment according to  FIG. 1 , two terminal openings  26  exist in the terminal face  24  of the cover part  22 , and behind each terminal opening  26  a tubular hollow body  28  is located, moulded onto the terminal face, as guide means for the connecting conductor and as spring actuating means. In this arrangement, each terminal opening  26  and each guide means  28  is allocated to one of the two partial clamping springs  13   a ,  13   b  as have been produced by the slot  2181  in the clamping spring  12 . Thus, if two conductors are to be clamped down, a conductor  14  is inserted through each of the two terminal openings  26  and clamped on by in each case one of the partial clamping springs  13   a ,  13   b . The connecting conductors  14  are separated and guided in the hollow bodies  28  used as guide means for the connecting conductors  14  and thus no separate guiding or separating devices are required at the terminal connection  10 . In particular, it is not required to subdivide the opening  116  into two receiving spaces by means of a web. Neither is it required to separate the two partial clamping springs  13   a ,  13   b  by means of a great distance between the two. They can be located close to one another with their narrow longitudinal side. 
     The terminal connection  10  can thus be constructed in a very simple and narrow manner so that it can be installed in an installation switching device of half a module width. 
     It can be seen that, overall, only three components are required: the conductor bar  102 , the clamping spring  12  and the cover part  22 . This greatly simplifies the assembly. 
     Due to the spring force of the clamping spring  12 , the cover part  22  is pressed outwards against the projection  234  in the state of rest so that the cover part always assumes a defined position in the state of rest. 
     The cover part thus fulfils two functions: on the one hand, the functions of guidance of the connecting conductors and, on the other hand, the function of the spring actuating tool. Both rigid and flexible conductor ends can be clamped in and also removed again from the terminal by means of the device according to the invention, without an external actuating tool for the clamping spring. 
     Naturally, there could also be an additional slot in the terminal face  24  of the cover part  22  through which an external tool could then be pushed for operating the clamping spring  12 . 
     Furthermore, a test opening  236  is arranged in the terminal face  24 . The clamping spring  12  can be electrically contacted by means of a test probe through this test opening. 
     In the embodiment shown in  FIG. 1 , the terminal face  24  of the cover part  22  extends inclined towards the rear face  5 . The guide means  28  are approximately perpendicular to the terminal face  24 . The angle of inclination with which the connecting conductor  14  is introduced into the terminal is thus determined by the angle of inclination of the terminal face  24 . An embodiment is also conceivable in which the terminal face  24  extends approximately in parallel with the rear face  5  and the guide means  28  are inclined with respect to the terminal face  24 . The angle of inclination with which the connecting conductors  14  are inserted into the terminal is then determined by the angle of inclination of the guide means  28  with respect to the terminal face  24 . 
     The cover part  22  can be produced very advantageously as injection moulded part of plastic in one injection process. 
       FIGS. 4   a ,  4   b ,  5  show further variants of an installation switching device according to the invention. Only the essential differences with respect to the embodiments explained previously will now be discussed. 
     In the embodiment according to  FIGS. 4   a  and  4   b , the terminal connection space is placed lower, that is to say arranged further away from the rear face  5  in the direction of the mounting side  6  in the housing  3  of the installation switching device  1 . The resultant greater distance of the terminal face  24  from the rear face  5  is compensated for by a spacing area  238  which is moulded onto the cover part  22  following the terminal face  24  as additional part-area. The spacing area  238  carries at its free end a second operating area  240  which is approximately flush with the rear face  5  when the cover part  22  is inserted. In this case, the test opening  236  is arranged in the second operating area  240 . Placing the terminal connection space  18  lower brings further operating advantages when inserting the connecting conductors  14 . The terminal connection  10  can now also be operated from the front face via the second operating area  240 . 
     Furthermore, the projection  234  used as stop is attached laterally at the wide sides of the housing in the embodiment according to  FIGS. 4   a  and  4   b.    
     In the embodiment according to  FIG. 5 , the terminal connection space is placed even lower, that is to say arranged further apart from the rear face  5  in the direction of the mounting side  6  in the housing  3  of the installation switching device  1 . The terminal cover part  22  here has a web  242  pointing away perpendicularly from the terminal face, between the two terminal openings  26 . The web  242  is also supported on the elongated spacing area  238  of the cover part  22 . The web  242  is used for stiffening and thus for increasing the mechanical strength. The cover part  22  can be produced very advantageously as an injection moulded part in one injection process also with the web  242 . 
       FIG. 7  shows a partial sectional view of the terminal connection space  18  of a further installation switching device  1  according to the invention. 
     The installation switching device  1  has an insulating housing, formed of two housing parts  2 , with a front face  304 , a rear face  305 , a mounting side  6 , a front narrow side  7 , a rear narrow side  8  and two wide sides  9 , only one of which, located in the plane of the drawing, is shown in the view according to  FIG. 1 . 
     The terminal connection space  18  is limited laterally, that is to say towards the wide side, by the housing wide sides  9  of the insulating housing  3 . 
     Towards the front face  304 , an opening  20  of the terminal connection space  18  is formed by an opening in the rear face  305  of the housing part  2 , through which the terminal connection  10 , fixed in position in the terminal connection space  18 , is accessible for the connection of connecting conductors  14 . The front narrow side  7  is initially adjoined by a part piece  356 , at the housing side, of the rear face  305 . This produces an opening  20  at the rear face  305  in the area between the end of the part piece  356  at the housing side, facing away from the front narrow side  7 , and the rear narrow side  8 . 
     Due to a further opening at the rear narrow side  8  of the housing part  2 , the opening  20  of the terminal connection space  18  extends beyond the contact edges between the rear narrow side  8  and the rear face  305  into the rear narrow side  8 . This has the advantage that increased flexibility is given for the direction of connection of the connecting conductor  14 . 
     The terminal connection  10  described in the text which follows essentially corresponds to the terminal connection already described above in  FIGS. 1-6 . It comprises a conductor bar  102  and a clamping spring  312 . The terminal connection  10  is fixed in position in the terminal connection space  18 , in a manner known per se, on the inside of the wide side  9  by means of webs  104  and pins  106 ,  108 . The terminal connection  10 , fixed in position in the terminal connection space  18 , is located between the rear narrow side  8  and the rear mounting side  6  in the area of the contact edge. 
     The conductor bar  102  of the terminal connection  10  comprises a connecting end  112  and an adjoining discharge area  114 . At the connecting end  112 , it has a window-like opening  116  with a support edge  118  and a clamping edge  120  opposite the support edge  118 . The clamping edge  120  is located at the transition of the connecting end  112  into the discharge area  114 . 
     The clamping spring  12  has a support leg  212  with which it is supported on the support edge  118  of the conductor bar  102 . It can be supported in such a manner that the support leg  212  has at its free end an upward bend with which it partially encloses the support edge  118  for the purpose of supporting it. 
     The support leg  212  is adjoined by an arc piece  214  which is adjoined by a clamping leg  216 . The conductor end of a connecting conductor (not shown here) is inserted into the window-like opening  116  from the side of the arc piece  214  and can be clamped tight between the clamping leg  216  and the clamping edge  120 , acting as abutment. The free end of the clamping leg  216  passes through the window-like opening  116 . 
     The conductor bar  102  approximately has a U-shaped basic form, the connecting end  112  forming the first U-leg and the discharge area  114  being formed by a crossbar  220  and the second U-leg  222 . At the free end of the second U-leg  222 , an upward bend  224  is attached. At this upward bend  224 , further connecting conductors can be attached by means of which the terminal connection  10  is connected to other assemblies within the switching device housing such as, for example, the tripping assemblies. In particular, the connecting conductors can be welded on or hard-soldered onto this upward bend and screwing-on is also possible. 
     In the embodiment of a terminal connection which is shown in  FIG. 1 , the upward bend is elongated to form a discharge bar  226  at the free end of the second U-leg  222 . The discharge bar  226  is thus positively connected with the second U-leg  222 ; it points approximately perpendicularly from the latter in the direction of the window-like opening  116  and projects over the latter. 
     In this embodiment, the arc piece  214  is first adjoined by a first part-clamping leg  27  which changes into a second part-clamping leg  218 , bent away from the first part-clamping leg  217 , at a bending edge  219  so that the first and the second part-clamping leg  217 ,  218  assume an obtuse angle with respect to one another. The opening of the obtuse angle points into the direction of insertion of the connecting conductor, the bending edge  219  is located approximately in the centre of the clamping leg  216 . 
     The opening  20  of the terminal connection space  18  is covered by a terminal cover part  22  swivelably connected with the housing part  2 . 
     The terminal cover part  22  comprises a first part-body  322 , longitudinally extended in the direction of the rear narrow side  8  and coupled swivelably to the housing part  2  via a hinge pin  232 , and a closing part  354  swivelably coupled to its free end via a hinge  352  which extends approximately in parallel with the rear face  305 . To improve the mobility in the hinge  352 , it is constructed as film hinge. 
     The first part-body  322  comprises a first cover plate  323  which covers the terminal connection space  18  in the lower part, adjoining the mounting side  6 , of the narrow side  8  and which carries an approximately tube-like counterpiece to the hinge pin  232  with which it is coupled swivelably at the hinge pin. The first cover plate  323  has a pressure area  330  which is accessible from the outside and can be operated manually. 
     In the vicinity of the free end of the pressure area  330 , the first cover plate  323  is connected via an intermediate piece  325 , pointing into the interior of the housing, with a spacing area  338  which also extends in parallel with the rear narrow side  8  in the direction of the face  305  and covers the terminal connection space  18  in the upper part of the narrow side  8 , adjoining the rear face  305 . 
     At the free end of the spacing area  338 , the aforementioned film hinge  352  with the closing part  354 , coupled swivelably thereto, is located. 
     This is a plate which, at its free end, overlaps at least partially the part  356  at the housing side of the rear face  305 . The closing part  354  and the part  356  at the housing side of the rear face thus together form the rear face  305 . 
     At its free end, the closing part  354  carries pins  358  protruding laterally, pointing in the direction of the wide sides  9 . In the housing, a rocker-like guide  360  is attached close to the part  356  at the housing side, of the rear face  305 , in such a manner that the pins  358  are accommodated in the guide  360 . 
     If then the terminal cover part  22  is swivelled in the direction of the interior of the device by pressure on the pressure area  330 , the closing part  354  will slide behind the part  356  at the housing side, of the rear face  305 , and is guided by the rocker-like guide  360  displaceably in parallel with the latter. During this process, the angle changes between the closing part  354  and the spacing area  338 . 
     Thus, the closing part  354  and the spacing area  338 , in the closed position according to  FIG. 7 , form an acute angle with one another which is open towards the interior of the housing. In the position according to  FIG. 2 , the closing part  354  and the spacing area  338  form an obtuse angle with an opening into the interior of the housing when the terminal cover part  22  is swivelled into the interior of the housing. 
     On actuation of the terminal cover part and the associated swivelling about the hinge pin  232 , the closing part  354  and the spacing area  338  also perform a swivelling movement with respect to one another around the film hinge  352 . 
     By attaching the film hinge between the closing part  354  and the spacing area  338 , the closing part  354  can thus shift approximately parallel behind the part  356  at the housing side, of the rear face  305 , in a space-saving manner 
     The intermediate piece  325  has a terminal face  324  pointing towards the outside. There is at least one terminal opening  26  in the terminal face  324 . Starting from the terminal opening  26 , a tube-like opening  28  passes through the intermediate piece  325 , which penetrates the intermediate piece  325  approximately perpendicularly starting from the terminal face  324  and is thus used as guide means for a connecting conductor to be connected to the terminal connection  10 . 
     The connecting conductor is guided through the terminal opening  26  in the terminal cover part  22  and, after leaving the tube-like opening  28 , encounters the clamping leg  216  of the clamping spring  312 . 
     If the connecting conductor is a rigid conductor, the clamping leg  216  of the clamping spring  312  can be pressed away from the clamping edge  120 , by means of the connecting conductor alone, to such an extent that the connecting conductor can be inserted and clamped tight in the window-like opening  116  between the free end of the clamping leg  216  and the clamping edge  120 . 
     In the case of a flexible connecting conductor, the window-like opening  116  must first be opened in another way. 
     This is done by swivelling the terminal cover part  22 . 
     In the vicinity of the tube-like opening  28 , the terminal cover part  22  carries at the intermediate piece  325  a nose  30 , pointing towards the clamping leg  216 , which is used as spring actuating means. 
     Naturally, the nose  30  can also be other protruding components, in particular, the function of the nose  30  could also be formed by a web surrounding the exit opening of a tube-like opening  28  in the manner of a collar. 
     Due to the restoring spring force of the clamping leg  216 , the latter presses the nose  30 , and thus the terminal cover part  22 , towards the outside. 
     The terminal cover part  22  is swivelled inwards by pressure on the pressure area  330  or on the spacing area  338 , and the clamping leg  216  is pressed away from the clamping edge  120  via the nose  30  to such an extent that the window-like opening  116  becomes free for inserting the connecting conductor, see  FIG. 8 . 
     The nose  30  is moulded onto the terminal cover part  22  and constructed in such a manner that, when the cover part is swivelled against the clamping spring, it loads it to open close to the bending edge  219 . 
     Due to its alignment in such a manner that it loads the clamping spring to open close to the bending edges when the cover part is swivelled, less force expenditure is required during the opening actuation of the terminal cover part, the opening area in the clamping window remaining of the same size. 
     In an actual example, the first and second part-clamping leg  217 ,  218  form an angle of approximately 160°. With respect to a clamping spring with straight unbent clamping leg  216 , otherwise unchanged, the introduction of the angle halves the actuating force with maximum terminal aperture. 
     A corresponding procedure is adopted for detaching a connecting conductor clamped on. Pressure on the terminal cover part  22  detaches the clamping between the clamping leg  216  and the connecting conductor in the manner described above so that the latter can be pulled out of the window-like opening  116 . Due to the kinked construction of the clamping leg  216 , described above, the actuating force for detaching the connecting conductor is also much lower. 
     A corresponding procedure is adopted for detaching a connecting conductor clamped on. Pressure on the terminal cover part  22  loosens the clamping between the clamping leg  216  and the connecting conductor in the manner described above, so that the latter can be pulled out of the window-like opening  116 . 
     As an alternative, the opening movement of the terminal cover part  22  can also be effected by a commercially available longitudinal-slot or crossed-slot screwdriver  364 . For this purpose, the latter is placed into a receiving opening  350 , suitable for reception (slot-, cross-shaped or spherical recess) at the spacing area  338  at an acute angle and the terminal is opened by a pressure movement with the screwdriver  364 . 
     Even if only one terminal opening  26  and only one tube-like opening  28  are shown in the representation according to  FIGS. 7 and 8 , two or more such terminal openings and recesses can naturally also be provided for receiving and connecting a number of connecting conductors in the intermediate piece  325 . All connected connecting conductors can be clamped on with a common clamping spring via its clamping legs  216 . When the terminal cover part  22  is actuated, all connected conductors are then released simultaneously and can be detached simultaneously. 
     In a further embodiment, to which, however, the same  FIGS. 7 and 8  apply as diagrammatic drawings, the terminal cover part  22  with the first part-body  322 , the hinge  352  and the closing part  354  consists of two material components having different mechanical properties. 
     These are joined to one another in a two-component injection moulding process. 
     The result is a hard/soft compound. The hard component forms the major component. The first part-body  322  is produced from this. It is used for transferring the actuating forces to the clamping spring  312  and during this process preventing or at least minimizing a bending-through of the component. 
     The soft component is used in the area of the hinge  352  and of the closing part  354 . 
     This provides for easy mobility of the hinge which is required so that the angular change of the angle between the closing part  354  and the first part-body  322  on actuation of the terminal cover part  22  as described above can be easily adjusted. 
     In this embodiment, the hinge  352  does not necessarily have to be a film hinge. This is because the mobility of the hinge is ensured by the choice of a flexible material in the hinge area and not by the thickness of the hinge alone. 
     Flexibility of the closing part  354  also contributes to the latter being able to bend to some extent when it is displaced in parallel with the rear face  305  towards the front narrow side  7  in the rocker-like guide  360 , and can thus rest against the front narrow side  305  even more easily and narrowly. 
     Overall, this leads to a very close guidance of the closing part  354  at the rear face  305 , and thus to great space saving during the swivelling of the terminal cover part  322 . 
     LIST OF REFERENCE DESIGNATIONS 
     
         
           1  Installation switching device 
           2  Housing part, housing 
           3  Housing 
           2   a  Partition line 
           4  Front face 
           5  Rear face 
           6  Mounting side 
           7  Front narrow side 
           8  Rear narrow side 
           9  Wide side 
           10  Screwless terminal connection 
           12  Clamping spring 
           13   a, b  Part-spring 
           14  Connecting conductor 
           16  Stripped connecting conductor end 
           18  Terminal connection space 
           20  Terminal connection space opening 
           22  Cover part, terminal cover part 
           24  Terminal face 
           26  Terminal opening 
           28  Guide means, tube-like opening 
           30  Spring actuating means, nose 
           102  Conductor bar 
           104  Web 
           106  Pin 
           108  Pin 
           110  Projection 
           112  Connecting end 
           114  Discharge area 
           116  Window-like opening 
           118  Support edge 
           120  Clamping edge 
           212  Support leg 
           214  Arc piece 
           216  Clamping leg 
           217  First part-clamping leg 
           218  Second part-clamping leg 
           219  Bending edge 
           220  Crossbar 
           222  Second U-leg 
           224  Upward bend 
           226  Discharge bar 
           228  Upward bend 
           230  Pressure area 
           232  Hinge pin 
           234  Projection 
           236  Test opening 
           238  Spacing area 
           240  Second operating area 
           242  Insulating web 
           304  Front face 
           305  Rear face 
           312  Clamping spring 
           322  First part-body 
           323  First cover plate 
           324  Terminal face 
           325  Intermediate piece 
           330  Pressure area 
           338  Spacing area 
           350  Access opening 
           352  Hinge 
           354  Closing part 
           356  Part at the housing side, of the rear face 
           358  Pin 
           360  Rocker-like guide in the inner wide side 
           364  Screwdriver 
           2181  Slot