Patent Publication Number: US-6657148-B2

Title: Multipole contact block

Description:
FIELD OF THE INVENTION 
     The present invention relates to a three-pole contact block, in particular with sudden disconnection and positive opening, utilisable in a switch sensitive to a pushing movement, in particular a position switch, a push button or analogous element. 
     BACKGROUND OF THE INVENTION 
     Generally, such blocks comprise a casing for housing fixed contact parts terminated at one end by connection lands and carrying at another end a fixed contact together with a movable element provided with several contact bridges in such a way as to have at least one opening pole and one closure pole with the fixed contacts. The movable element is subjected to a push-button on the one hand and a spring system on the other, the whole being fitted to produce a positive opening and sudden opening and closure. 
     It is known from prior art how to implement a contact block in a multipole switch with a push button which acts upon a contact carrier with several superposed bridges, the bridges being mounted in a reversible way in order to ensure a “normally open” (NO) or “normally closed” (NC) function with the corresponding pole. 
     In certain cases it is preferable to confer to one of the poles of a three-pole switch an NO or NC function without having to modify the contact carrier. 
     SUMMARY OF THE INVENTION 
     The aim of the invention is to enable a multipole contact block to operate with at least one pole switchable from normally open state to normally closed state or the reverse, without modification of the layout of the contact carrier. 
     According to the invention, the connection lands are laid out according to at least three distinct connection planes, and the movable element has at least three contact bridges separated in such a way as to cooperate with fixed contacts located in two transversal contact planes and to move in two frontal planes; two contact bridges which are situated in the first frontal plane co-operating with fixed contact parts protruding on two connection planes, and the third contact bridge which is situated in the second frontal plane cooperating with the fixed contact parts protruding on the third connection plane. The third connection plane is in particular located in a median position between the two first connection planes. 
     Preferably the contact block is three-pole and the movable element that has four contact bridges with a balanced symmetrical arrangement, the fourth contact bridge being located in the second frontal plane and not co-operating with the fixed contact parts. 
     The movable element can be substituted at the fourth contact bridge by an elastic or mobile support part located in the second frontal plane relative to the third contact bridge located in this plane, so as to be displaced at the same time as the contact bridge located in the same transversal plane. 
     Advantageously the contact bridges located at different levels in a same frontal plane are acted upon by a single compression spring tending to separate them from each other. 
     In a simplified assembly embodiment, the movable element is mounted in the casing by introduction via an open rear face of the casing and a base is assembled, preferably clipped together with the casing to cover the rear face. The base can then have lugs or analogous maintenance elements which bear against the fixed contact parts ending at the rear plane to help to maintain them in a very simple way. A cover for insulating the terminals can be set, in particular clipped, on the front face of the casing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following description relates to a non-limiting embodiment of the invention, relative to the attached drawings. 
     FIG. 1 shows a contact block according to the invention, in perspective. 
     FIG. 2 is a diagram of a front view of a part of the block. 
     FIGS. 3 and 4 are diagrams from the side of the block, with movable elements removed, in two different configurations. 
     FIG. 5 shows a side view of the movable element of the block. 
     FIG. 6 is a view of the fixed conducting parts only, in perspective. 
    
    
     DISCLOSURE OF THE INVENTION 
     The three-pole contact block shown in the figures comprises a casing  10  in insulating material which houses six conducting parts  11 ,  12 ,  13 ,  14 ,  15 ,  16  carrying fixed contacts and a movable element  17  with positive opening and sudden opening and closure, the element being guided inside this casing and provided with mobile contacts which co-operate with the fixed contacts. 
     The casing  10  is quadrangular in shape and towards the front has three groups of two terminals  21 ,  22 ,  23 ,  24 ,  25 ,  26  divided over three respective connection planes P 1 , P 2 , P 3 . Each terminal  21 - 26  comprises a screw  27  for tightening the cable (or an elastic tightening part) co-operating with a connection land  28  of the corresponding conducting part  11 - 16 . The conducting parts  11 ,  12  and  15 ,  16  associated with the terminals  21 ,  22  and  25 ,  26  located in the end connection planes P 1 , P 3  are preferably identical; the conducting parts  13 ,  14  associated with the median terminals  23 ,  24  of the median plane P 2  differ from the other conducting parts and are preferably identical to each other (see FIG.  6 ). 
     At their end opposite to the connection land  28 , the parts  11 - 16  terminate by a fixed contact  29  under the form of a pad; the contact pads  29  of parts  11 ,  12 ,  15 ,  16  are located in a rear frontal plane PR (parallel to the base and to the front face of the block and perpendicular to the planes P 1 -P 3 ) and those of parts  13 ,  14  are located in a fore frontal plane PF parallel to PR. Heightwise, the pads  29  of the parts  11 ,  12  are located in an intermediate plane P 4  between P 1  and P 2  and those of parts  15 ,  16  are located in an intermediate plane P 5  between P 2  and P 3 ; the pads of parts  13 ,  14  are located in the plane P 4  or P 5  according to the configuration chosen for the block, as will be described below. 
     The casing  10  of the block provides a fixation lug  18 , for example to be housed in a position switch body. The casing  10  is covered in front by a clippable cover  30  which ensures a function of protection and impermeability of the terminal screws. The cover  30  has a wall  31  forming the front face of the block while allowing access to the screws, as well as the inter-terminal insulation partitions  32  and lateral notches for clipping onto the front edges of the block. The casing  10  has an open face  33  at the rear which allows introduction of the contact block and which is closed by a clippable base  34 . The base  34  has a flat wall provided with lugs  35 , towards the interior of the block, which ensure maintenance of the rear fixed contact parts  11 ,  12 ,  13 ,  14 . Instead of lugs, one can provide shoulders or other analogous forms of maintenance. The base  34  also comprises clipping lugs  36  on the casing. 
     The movable element  17  is able to generate a positive opening of the contacts. It comprises a push button  40  which can be displaced along a direction Z parallel to the planes PF, PR and, subjected to a return spring  41  as well as a contact carrier  42  with sudden movement, also movable along Z. The contact carrier  42  is mounted to be mobile in to-and-fro motion on the push button and is subjected to a return part  43 . This return part, by means of movement reversing levers, transforms a lowering movement of the push button into a rising movement of the contact carrier. The rising movement of the contact carrier  42  is caused to be sudden with the aid of two lateral springs  44  when passing the dead point position. The mechanism described in already known from prior art is not the subject of the invention. 
     Four contact bridges  45 ,  46 ,  47 ,  48  are set out in a symmetric and balanced manner on or in the contact bridge  42  in such a way as to be able to be displaced relative to the latter along Z. The planes of symmetry of the bridges are the same as the front planes PF and PR. The bridges  45 ,  46  are located in the plane PR and the bridges  47 ,  48  in the plane PF; the bridges  45 ,  47  on the one hand, and the bridges  46 ,  48  on the other hand, are located in two distinct planes parallel to P 1 -P 3 , in such a way as to be able to co-operate respectively with the parts  11 ,  12  (bridge  45 ),  15 ,  16  (bridge  46 ),  13 ,  14  (bridge  47  or bridge  48  according to the assembly adopted for parts  13 ,  14 ). Each bridge has, in the middle, a cast moulded insulated part  49  which facilitates guiding it in the contact carrier. Between the bridges  45 ,  46  on the one hand and the bridges  47 ,  48  on the other, a compression spring  50  is provided which bears directly on the bridges and tends to separate them from each other to ensure clearance compensation and good contact pressure, particularly at the moment of switchover. As a variant, in the place of one of the front bridges  47 ,  48  one can provide an elastic or mobile support part  51  (see FIG.  4 ), for example an elastic blade able to simulate, when the movable element  17  is activated, the retraction movement of the bridge for which it is substituted and to follow the movement of the rear bridge located at the same level. 
     The bridges  45 ,  47  form, together with the corresponding fixed contacts, normally open poles (NO) and the bridges  46 ,  48  form, together with the corresponding fixed contacts, normally closed poles (NC). 
     The block described is assembled in the following way. The fixed contact parts are set in the casing  10 , and then the movable element is inserted from the back into the casing and the base  34  is clipped onto the casing. The two configuration possibilities of the block are illustrated in FIGS. 3 and 4. In the version of FIG. 3, the fixed contact parts  13 ,  14  are set with their contact pads in the plane P 4  to form an NO pole. In the version of FIG. 4 the parts  13 ,  14  are set with their contact pads in the plane P 5  to form an NC pole. Furthermore, in the version of FIG. 4 the bridge  47  has been replaced by an elastic support part for the spring  50 . The parts  13 ,  14  of the NO version can be identical to the parts  13 ,  14  of the NC version, such that one passes from one version to the other by simple turnover, or they can be different. In the same way, the casing  10  of the version NO-NO-NC of the contact block can be identical to the casing of the version NO-NC-NC of the block or can be different.