Patent Publication Number: US-7901255-B2

Title: Overvoltage protection magazine

Description:
This application is a National Stage Application of PCT/EP2007/010937, filed 13 Dec. 2007, which claims benefit of Serial No. 10 2007 006 693.9, filed 12 Feb. 2007 in Germany and which applications are incorporated herein by reference. To the extent appropriate, a claim of priority is made to each of the above disclosed applications. 
     BACKGROUND 
     The invention relates to an overvoltage protection magazine for insertion into a terminal block for telecommunications and data technology. 
     An overvoltage protection magazine such as this is known, for example, from DE 103 17 621 A1. 
     DE 10 2004 017 605 B3 discloses a plug connector for printed circuitboards, having a number of contact elements, with the contact elements each having two connection sides, with one connection side being in the form of an insulation-displacement contact for connection of cores, and with the other connection side being in the form of a fork contact for making contact with connecting pads on a printed circuitboard. The contact element is in this case formed in two parts, with a first part of the contact element comprising the insulation-displacement contact and the second part comprising the fork contact, with one contact limb being arranged on each of the two parts of the contact element, and with the two contact limbs forming an isolating contact. An overvoltage protection magazine can then be inserted into a row of isolating contacts such as these. 
     SUMMARY 
     The invention is based on the technical problem of providing an overvoltage protection magazine of compact design. 
     For this purpose, the overvoltage protection magazine has a plastic housing, electrical contacts, overvoltage protection elements and at least one contact comb, with the electrical contacts being arranged in the plastic housing and each having an insertion area and a contact area, with the electrical contacts being arranged in a row in the insertion area, with the plastic housing having holders for the overvoltage protection elements which are arranged on both sides (left, right) along the longitudinal direction, with the contact areas of the electrical contacts projecting into the respective holder and producing a first electrical contact with the respective overvoltage protection element, and with the contact comb having sprung contact elements in the area of the holders, which produce the second contact with the overvoltage protection element. Since no overvoltage protection elements are arranged one above the other, the height of the overvoltage protection magazine is very small, with the two rows which are located alongside one another at the same time resulting in a high packing density. The actual fixing is provided mainly by the sprung elements of the contact comb from the outside, so that the plastic body need not absorb much force. Furthermore, this simplifies the configuration of the electrical contacts, since these need be only in the form of a rigid mating contact in the holder, for example in the form of a metal strip which is supported against the inner rear wall of the holder. The overvoltage protection elements are preferably in the form of two-pole gas surge arresters. The overvoltage protection element is preferably cylindrical, with the bottom surfaces having the contacts, that is to say with the bottom surface of the overvoltage protection element being pressed against the contact area of the electrical contact in the holder. The electrical contacts are preferably composed of metal, with the adjacent electrical contacts preferably being bent differently since they are arranged in a row in the insertion area, but with their contact area being passed alternately into the left-hand and right-hand holder. This embodiment has the advantage that it avoids contact crossings. 
     In one preferred embodiment, the contact comb is U-shaped and has sprung contact elements on each of its limbs. This has the advantage of balanced force distribution. 
     In a further preferred embodiment, the holders for the overvoltage protection elements are arranged offset with respect to one another on the two sides. On the one hand, this has the advantage that the electrical contacts can be guided more easily. A further advantage is more robustness. 
     In a further preferred embodiment, the sprung contact elements of the contact comb are in the form of cuts. For embodiments where the holders are arranged offset with respect to one another, the cuts are also offset from the two limbs, thus making the contact comb more robust. 
     In a further preferred embodiment, a ground contact is arranged at least one end of the contact comb, via which the overvoltage protection elements can be connected to ground or frame. 
     In a further preferred embodiment, the ground contact is in the form of a double fork contact or has two fork contacts. On the one hand, this provides a certain amount of redundancy for the ground connection, while on the other hand it increases the current carrying capacity. 
     In a further preferred embodiment, the electrical contacts are in the form of contact grids, which are stamped free through openings in the plastic housing. This has the advantage that the electrical contacts can also be extrusion coated easily during the production of the plastic housing, so that they are seated firmly in the housing. This is possible because the electrical contacts need not themselves be sprung, and, instead, all of the spring force is applied by the contact comb from the outside. The stamping process then results in the electrical contacts of the contact grid being subsequently electrically isolated from one another. 
     In a further preferred embodiment, the holders have a circular cross section, so that the preferably cylindrical overvoltage protection elements can be held easily. Furthermore, the holder is preferably open upwards to the upper face, with the opening angle being less than 180°, furthermore preferably being less than 90°. This prevents the overvoltage protection elements from being able to slide out upwards. 
     In a further preferred embodiment, sliding elements which are formed with an incline are arranged above the holders. This allows the overvoltage protection elements to be fitted from above despite a relatively small opening angle of less than 180°. In this case, these overvoltage protection elements run along the incline, and then drop obliquely into the holder. 
     In a further preferred embodiment, the edge of the incline projects beyond the overvoltage protection element. This results in the sprung contact elements of the contact comb sliding over the incline while the contact comb is being pushed on, and in the overvoltage protection element touching only the bottom surface. This reduces the risk of damage to the contact metallization on the overvoltage protection element. Furthermore, this improves the assembly reliability, since jamming or tilting of the overvoltage protection element is prevented. 
     In a further preferred embodiment, the contact comb is formed with at least one locking lug, which is preferably formed by cuts in the same way as the sprung contact elements. Furthermore, the contact comb preferably has two locking lugs, one on each side, but at opposite ends. In this case, by way of example, the locking between the contact comb and the plastic housing can be achieved in the form of a clip which clasps behind it, or a hole-and-pin connection. 
     In a further preferred embodiment, a hook is arranged above the ground contact and/or the fork contact and latches with the plastic housing, thus preventing the contact comb from being lifted off when the ground contact is pushed onto a ground rail. 
     One preferred application of the invention is overvoltage protection for a plug connector according to DE 10 2004 017 605 B3. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be explained in the following text with reference to one preferred exemplary embodiment. In the figures: 
         FIG. 1  shows a perspective illustration of a plastic housing with two-pole gas surge arresters inserted in it, 
         FIG. 2  shows a perspective illustration of a contact comb, 
         FIG. 3  shows a perspective side view of an overvoltage protection magazine, 
         FIG. 4  shows a perspective plan view of the overvoltage protection magazine, 
         FIG. 5  shows a side view of the overvoltage protection magazine, 
         FIG. 6  shows a plan view of the overvoltage protection magazine, with the contact comb partially removed, 
         FIG. 7  shows a cross section through the overvoltage protection magazine, and 
         FIG. 8  shows a perspective illustration of the electrical contacts in the form of a contact grid. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a plastic housing  10  with two-pole gas surge arresters  11  inserted in it. The plastic housing  10  has an upper face O, a lower face U and two ends S. Furthermore, the plastic housing  10  has a left-hand face left and a right-hand face right which respectively extend on the left and right from a web  13  which extends in the longitudinal direction L, with the upper face of the web  13  being the same as the upper face O of the plastic body  10 . The two-pole gas surge arresters  11  essentially have a cylindrical basic shape, with the contact metallizations being located on the bottom surfaces  36  of the cylinder while, in contrast, the envelope surface is isolated, with the exception of the rim areas  37 . The two-pole gas surge arresters  11  are arranged in the holders  12 , which are arranged in two rows on the left and right of the web  13  which extends in the longitudinal direction L. The web  13  forms a wall and separates the left-hand and right-hand sides (left, right). The holders  12  have a circular cross section. The individual holders  12  are subdivided by separating walls  14 , which are preferably planar. Sliding elements  15  are arranged above the holders  12 , and have an incline  16 . There is a hole  17  in each of the inclines  16 . The actual holder  12  is open at the top to the sliding elements  15 , with the opening angle being less than 90°, so that two-pole gas surge arresters  11  cannot slide upwards. For fitting from above, these slide off the incline  16  and drop obliquely, past the separating walls  14 , into the holders  12 . The holes  17  are dependent on the injection molding, since, when a contact grid  30  is being extrusion-coated, it must be held in position by pins. The holders  12  on the left-hand and right-hand sides (left, right) are each arranged offset with respect to one another, as can be seen particularly well in  FIG. 6 . One electrical contact  34  is in each case arranged on one wall of the holders  12  and has a contact area  33  which makes contact with the two-pole gas surge arrester  11 , as will be explained in more detail in the following text (see  FIG. 8 ). Furthermore, the plastic housing  10  has a latching hook  18  under the last sliding element  15 . 
     The electrical contacts are also injection molded as a contact grid  30  (see  FIG. 8 ) during the production of the plastic housing  10 . The contact grid  30  has a number of electrical contacts  34  corresponding to the number of holders  12 , and these are initially connected to one another by means of a lateral web  31 . Each electrical contact  34  has a straight insertion area  32 , which extends as far as the lateral web  31 . The insertion areas  31  of all of the electrical contacts  34  are in this case arranged in one row. The electrical contacts are first of all bent somewhat from the lateral web  31  and then merge again into a contact area  33 , which is arranged parallel to the insertion area  31 . In this case, there is a difference in the bending between adjacent electrical contacts. If the electrical contacts  34  are numbered successively, then all of the even numbers are in each case bent in the same way, and all of the odd numbers are bent in the same way. A plastic wall is then formed between adjacent contacts during extrusion coating with plastic, and separates the holders  12  on the left-hand and right-hand sides, with the contact areas  33  remaining free on one side in the direction of the respective holder  12 , where they make contact with the two-pole gas surge arresters  11 . After extrusion coating, the lateral web  31  between two electrical contacts is then stamped away. The openings  19  in the plastic housing  10  are used for this purpose. 
       FIG. 2  shows the contact comb  20 , which is plugged from above onto the plastic body  10 , which is fitted with two-pole gas surge arresters  11 . The contact comb  20  is essentially U-shaped, with sprung contact elements  21  being arranged on the two limbs and being formed by cuts from the limbs. In this case, on the lower face, each of the sprung contact elements  21  have a bend  22  which is directed inwards and makes the actual electrical contact with the two-pole gas surge arrester  11  (see also  FIG. 7 ). Furthermore, the contact comb  20  has two locking lugs  23 , which also each have a bend  24 . The two locking lugs  23  are narrower than the sprung contact elements  21 , and interact with the latching hooks  18 . A ground contact  25  is arranged at one end of the contact comb  20 , and is preferably formed integrally from the contact comb  20 . The ground contact  25  is likewise U-shaped, with a fork contact  28  being arranged on each of its two limbs  27 . A hook  29  is arranged above each of the fork contacts  28  and locks the contact comb  20  and the plastic housing  10  to one another, so that the contact comb  20  cannot be lifted off when being pushed onto a grounding rail. When the contact comb  20  is being pushed on, the hooks  29  first of all run in grooves  35  at the end S, in order then subsequently to hook on the lower face U. 
     The complete overvoltage protection magazine  1  is illustrated in  FIGS. 3 to 5 , as created after the contact comb  20  has been pushed onto the populated plastic body  10 . In this case,  FIG. 5  also shows two pins  2 , which are used for latching of the overvoltage protection magazine  1  to the terminal block or plug connector for telecommunications and data technology. 
       FIG. 6  shows how the contact area  33  of the electrical contacts  34  is on the one hand embedded in plastic and on the other hand has one side which projects into the holder  12 , in order to make contact there with the two-pole gas surge arrester  11 , from one side. The other contact with the two-pole gas surge arrester  11  is made by means of the bend  22  of the sprung contact element  21 , as illustrated in  FIG. 7 . This figure also shows that the incline  16 , or the attachment or edge  3  adjacent to it projects beyond the two-pole gas surge arrester  11 , so that the bend  22  does not strike the rim area  37  of the two-pole gas surge arrester  11 , but rests directly on its bottom surface  36 . 
     LIST OF REFERENCE SYMBOLS 
     
         
           1  Overvoltage protection magazine 
           2  Pin 
           3  Edge 
           10  Plastic housing 
           11  Two-pole gas surge arrester 
           12  Holders 
           13  Web 
           14  Separating walls 
           15  Sliding elements 
           16  Incline 
           17  Hole 
           18  Latching hook 
           19  Openings 
           20  Contact comb 
           21  Sprung contact elements 
           22  Bend 
           23  Locking lugs 
           24  Bend 
           25  Ground contact 
           27  Limb 
           28  Fork contacts 
           29  Hook 
           30  Contact grid 
           31  Lateral web 
           32  Insertion area 
           33  Contact area 
           34  Electrical contact 
           35  Groove 
           36  Bottom surface 
           37  Rim area 
         L Longitudinal direction 
         O Upper face 
         U Lower face 
         S End 
         Li Left-side 
         Re Right-side