Patent Publication Number: US-2012033339-A1

Title: Surge protection magazine for a device in telecommunications and data technology

Description:
The invention relates to an overvoltage protection magazine for a telecommunications and data technology device. 
     DE 103 17 621 A1 has disclosed a generic overvoltage protection magazine for a telecommunications and data technology device, comprising a housing, a printed circuit board, a plurality of surge arresters and at least one grounding contact, the surge arresters being arranged on the printed circuit board and being connected to contact pads arranged on the printed circuit board via conductor tracks, which contact pads, in the plugged state, come into electrical contact with contacts of the telecommunications and data technology device, the housing having slit-shaped openings on the lower side for the parts of the printed circuit board which bear the contact pads and having at least one opening for the at least one grounding contact, that part of the grounding contact which is plugged through the opening being in the form of a single fork contact. The other part of the grounding contact, which is used for making contact with a grounding cable on the printed circuit board, is in this case in the form of a double fork contact. 
     Furthermore, the slit-shaped opening for the grounding contact is arranged in such a way that it is offset with respect to the slit-shaped openings of the printed circuit board. 
     DE 197 08 802 C2 has disclosed an electrical circuit arrangement of a staggered protective circuit, comprising a three-pole surge arrester, two PTC thermistors and two diodes for safeguarding an a,b twin core. 
     The invention is based on the technical problem of providing a generic overvoltage protection magazine which has a simpler design and manufacture. 
     The solution to the technical problem results from the subject matter having the features of claim  1 . The further advantageous configurations of the invention result from the dependent claims. 
     In this regard, the overvoltage protection magazine for a telecommunications and data technology device comprises a housing, a printed circuit board, a plurality of surge arresters and at least one grounding contact, the surge arresters being arranged on the printed circuit board and being connected to contact pads arranged on the printed circuit board via conductor tracks, which contact pads, in the plugged state, come into electrical contact with contacts of the telecommunications and data technology device, the housing having slit-shaped openings on the lower side for the parts of the printed circuit board which bear the contact pads and having at least one opening for the at least one grounding contact, that part of the grounding contact which is plugged through the opening being in the form of a single fork contact, the opening for the grounding contact being a slit-shaped opening for the printed circuit board or a separate slit-shaped opening, which is positioned on a line with the slit-shaped openings of the printed circuit board, the grounding contact having a second single fork contact, for making contact with the printed circuit board, the planes of the two single fork contacts being rotated through 90° with respect to one another, the grounding contact being formed in one piece. As a result, the printed circuit board is in one plane with the single fork contact, which is plugged through the housing lower side and is intended to produce the external connection to ground, for example by means of making contact with a limb of a mounting trough. Preferably, the overvoltage protection magazine in this case has two grounding contacts. 
     In a further preferred embodiment, at least one guide and one stop element for the grounding contact are arranged on the inner side of the lower side, with the slit-shaped opening running between said guide and stop element. This ensures that the grounding contact cannot slide through the slit-shaped opening. As a result of the guide, in this case the single fork contact is aligned with respect to the slit-shaped opening and at the same time is also guided in a defined manner with respect to the stop element. In embodiments with two grounding contacts, correspondingly two guides and two stop elements are provided, which are preferably arranged transposed with respect to the slit-shaped opening, with the result that only one design of the grounding contact is required. 
     In a further preferred embodiment, the guide is in the form of an elevation with a U-shaped cross section, the limbs of the elevation pointing towards the slit-shaped opening. 
     In a further preferred embodiment, the stop element is in the form of a square, which is flatter than the guide. In this case it is true that preferably the stop element is flatter than the guide, irrespective of its configuration. 
     In a further preferred embodiment, the overvoltage protection magazine has a cover, which is connected, preferably screwed, to the housing and fixes the printed circuit board in the housing. 
    
    
     
       The invention will be explained in more detail below with reference to a preferred exemplary embodiment, in which: 
         FIG. 1  shows an exploded illustration of an overvoltage protection magazine in a front view, 
         FIG. 2  shows an exploded illustration of the overvoltage protection magazine in a view from the rear, 
         FIG. 3  shows a first perspective illustration of a grounding contact, 
         FIG. 4  shows a second perspective illustration of the grounding contact, 
         FIG. 5  shows a perspective illustration of the housing without the printed circuit board, 
         FIG. 6  shows a detail illustration of the housing, 
         FIG. 7  shows a detail illustration of the housing with the grounding contact plugged in, 
         FIG. 8  shows a perspective illustration of the printed circuit board with grounding contacts, and 
         FIG. 9  shows a perspective illustration of the overvoltage protection magazine in the assembled state. 
     
    
    
       FIGS. 1 and 2  each illustrate an overvoltage protection magazine  1 . The overvoltage protection magazine  1  comprises a housing  2 , a populated printed circuit board  3 , two grounding contacts  4  and a cover  5 . Ten three-pole surge arresters  6  and twenty PTC thermistors  7  are arranged on the front side of the printed circuit board  3 , and twenty diodes  8  are arranged on the rear side in order to realize a 10 twin-core overvoltage protection means. Reference is made to DE 197 08 802 C2 as regards the series connection of surge arresters  6 , PTC thermistors  7  and diodes  8 . Ten plug-in tongues  9  are cut out of the printed circuit board  3 , with two contact pads  10  being arranged on each plug-in tongue  9  on the front side and two contact pads  11  on the rear side, in this case only the contact pads  10 ,  11  for a plug-in tongue  9  being illustrated. The contact pads  10 ,  11  of the front and rear side are in this case not through-plated. In embodiments without PTC thermistors  7  and diodes  8 , the contact pads  10 ,  11  can be through-plated, on the other hand. Furthermore, the printed circuit board  3  has at least two contact pads  12  for the grounding contacts  4 , which are connected to the grounding cables of the surge arresters  6 . In this case, a respective contact pad  12  can also be arranged on the front and rear side of the printed circuit board  3  for each grounding contact  4 , as is illustrated in  FIGS. 1 and 2  as well, which contact pads  12  can also be through-plated. 
     First of all, the grounding contact  4  will be explained in more detail with reference to  FIGS. 3 and 4 . The grounding contact  4  comprises a first single fork contact  41  and a second single fork contact  42 , which are connected to one another via a bent connecting web  43 . In this case, the grounding contact  4  is preferably in the form of a stamped and bent part in one piece, the two single fork contacts  41 ,  42  being rotated through 90° with respect to one another, i.e. the plane E 1  is perpendicular to the plane E 2 . 
     The electrical contact between the second single fork contact  42  and the contact pads of the printed circuit board  3  is made in this case in the contact region  44 . The electrical contact between the first single fork contact  41  and electrically conductive parts of a mounting system, such as the limbs of a U-shaped trough, for example, is made in the contact region  45 . The lower sides  46 ,  47  form stop edges, which will be explained in more detail further below. Furthermore, the protruding lower side  48  or the edge  49  of the connecting web  43  forms an insertion edge, which will likewise be explained in more detail further below. 
       FIG. 5  illustrates the housing  2  without the printed circuit board  3  and the cover  5 . The lower side  20  of the housing  2  has six slit-shaped openings  21 , with one slit-shaped opening  21  being hidden visually by an end side  22 . Reinforcing ribs  25 , which are at the same time used as a rest for the cover  5 , are arranged on inner sides of the front and rear side  23 ,  24 . 
     Furthermore, the housing  2  has two elevations  27 , which are U-shaped in cross section, two stop elements  28  and two printed circuit board guides  29 , the elevation  27 , the stop element  28  and the printed circuit board guide  29  as well as the slit-shaped opening  21  being hidden by the front end side  22  on one side. The hidden elevation  27  and the stop element  28  are in this case transposed in terms of their arrangement in relation to the slit-shaped opening  21 , i.e. the hidden elevation  27  is on that side of the slit-shaped opening  21  which faces the front side  23 . Correspondingly, the grounding contact  4  is rotated through 180°. The slit-shaped opening  21 , through which the grounding contact  4  and the respectively outermost plug-in tongue  9  of the printed circuit board  3  is intended to be plugged, runs between the elevation  27  and the stop element  28 . In this case, the elevation  27  for guiding the grounding contact  4  is higher than the stop element  28 . 
       FIG. 6  shows an enlarged illustration in particular of the elevation  27  and the stop element  28 , and  FIG. 7  illustrates the grounding contact  4  in the plugged-in position. In this case, the grounding contact  4  is first rotated in such a way that the single fork contact  41  is aligned with respect to the slit-shaped opening  21 . The single fork contact  42  is aligned with respect to the elevation  27  and the lower edge  48  or edge  49  is plugged into the U-shaped guide of the elevation  27 . If the grounding contact  4  then slides down, the single fork contact  41  slides through the slit-shaped opening  21  until the lower edge  46  hits the stop element  28  and thus prevents any further sliding. 
       FIG. 8  illustrates the populated printed circuit board  3  with the plugged-on grounding contacts  4 , with the contact pads not being illustrated. The two single fork contacts  41  are in this case in the plane of the printed circuit board  3 . In this case, the printed circuit board  3  presses on the lower side  47 , which acts as a stop edge for the printed circuit board  3 . During mounting, first the two grounding contacts  4  are plugged in and then the printed circuit board  3  is plugged in. In this case, the two single fork contacts  41  are each arranged offset with respect to the adjacent end side  22  in relation to an imaginary center line of their associated single fork contacts  42 , in order thus to provide space for the two outer plug-in tongues  9  of the printed circuit board  3 . 
     Finally,  FIG. 9  illustrates the overvoltage protection magazine  1  in the assembled state, with the cover  5  being screwed on, and with the screws (not illustrated) being screwed through the openings  50  into the hollow cylinder  26 . 
     LIST OF REFERENCE SYMBOLS 
     
         
           1  Overvoltage protection magazine 
           2  Housing 
           3  Printed circuit board 
           4  Grounding contacts 
           5  Cover 
           6  Surge arrester 
           7  PTC thermistor 
           8  Diode 
           9  Plug-in tongue 
           10 - 12  Contact pads 
           20  Lower side 
           21  Slit-shaped opening 
           22  End side 
           23  Front side 
           24  Rear side 
           25  Reinforcing ribs 
           26  Hollow cylinder 
           27  U-shaped elevation 
           28  Stop elements 
           29  Printed circuit board guides 
           41 ,  42  Single fork contacts 
           43  Connecting web 
           44 ,  45  Contact regions 
           46 - 48  Lower sides 
           49  Edge 
           50  Openings