Abstract:
A field bus module assembly includes a generally rectangular base module adapted for mounting on a fixed support, an input/output module, and a connecting module for connecting the input/output module with the base module, the base module including a lateral projecting portion adapted for insertion in sealed relation within a corresponding recess contained in the base module of an adjacent assembly. The base module includes a housing formed of a synthetic plastic insulating material, a plurality of bus bar conductors mounted on the housing, a protective cover member covering the bus bar conductors, and a mass of encapsulating material hermetically sealing the space around the cover.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a field bus module assembly including a base module adapted for connection to a fixed support, and input/output module, and a connecting module for connecting the input/output module to the base module, characterized that sealing masses and sealing beads are provided for hermetically sealing the base and connecting modules against moisture. 
   2. Brief Description of the Prior Art 
   Electrical power distribution and communications systems including electrical and/or electronic modules are well know in the patented prior art, as shown by the instant Applicant&#39;s prior U.S. patents to Eggert, et al., U.S. Pat. Nos. 5,588,881, 5,615,079, and 5,629,831, and Glathe, et al., U.S. Pat. No. 5,722,862, among others. 
   As shown by the German patent No. DE 37 40 290, it is also known to provide base modules with bus bar contacts that may be arranged in a row on a mounting rail in step-by-step relation. Housings with electronic equipment with external connections to actuators, sensors and the like may then be connected with the base modules. 
   In the International Application No. WO 00/62376, there is disclosed a connection unit having an input/output electronics module mounted thereon by plug connector means, which assembly is arranged for mounting on a support rail. 
   In designing such electrical devices and systems, it has proven desirable for the field bus modules, together with the so-called “gateway” or entrance modules, and the power supply modules, to be protected against the penetration of moisture. In particular, the devices are to be protected against the penetration of water according to Industry Standard EP 67. 
   SUMMARY OF THE INVENTION 
   Accordingly, a primary object of the present invention is to provide a field bus base module assembly that is hermetically sealed and is substantially impervious to water. In accordance with the present invention, the assembly includes a base module adapted to be secured to a fixed support, an input/output unit, and a connecting unit connecting the input/output unit to the base unit, characterized in that the chamber containing the bus bar contacts is closed by a cover member and is hermetically sealed by a first mass of conventional encapsulating material. 
   According to another object of the invention, the base modules are sealed by themselves standing alone, and then the modules are connected together by further sealing means, thereby to avoid the penetration of moisture to achieve protection of Industry Standard IP67. To this end, at least one row of the contact boreholes is surrounded by a groove that contains a compressible sealing bead that is engaged by a corresponding rib on the housing of another unit, thereby further enhancing the sealing effect. 
   Still another object of the invention is to provide a sealing frame that is mounted in the connecting module for receiving the connector connecting pins, together with a second sealing mass of encapsulating material that further seals the assembly against moisture. By way of a simple design feature, the sealing frame also facilitates a watertight design and makes it easier to cast the sealing material therein. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the invention will become apparent from a study of the following specification when viewed in the light of the accompanying drawings, in which: 
       FIGS. 1   a - 1   f  are front perspective views illustrating the assembly steps for assembling an electrical system using the field bus module assembly of the present invention; 
       FIG. 2  is an exploded view of a field bus module assembly of the present invention; 
       FIGS. 3   a  and  3   b  are front perspective views illustrating the steps of assembling a connecting module to a base module in accordance with the present invention; 
       FIGS. 4   a - 4   c  are bottom perspective views illustrating the steps for installing the cover member and for subsequently applying the sealing mass on the bottom of the base module; 
       FIGS. 4   d - 4   f  are top perspective views illustrating the steps for laterally connecting together a plurality of the base modules of the present invention; 
       FIGS. 4   g  and  4   h  are perspective bottom views illustrating the manner of installation of the sealing frame within the bottom chamber defined within a connecting module in accordance with the present invention; and 
       FIGS. 4   i  and  4   j  are front perspective views illustrating the assembly of the connecting module to the base module. 
   

   DETAILED DESCRIPTION 
   Referring now to  FIG. 1   a , the electrical system includes a plurality of base module units  100  that are connected together in side-by-side relation. The base module units are connected with a pair of larger base module units  100 ′ that support the so-called “gateway” or input module  5  and the power supply module  7 , respectively, as shown in  FIG. 1   b . As shown in  FIG. 1   c , the connecting module  200  is mounted upon an associated one of the base modules  100 . The base module  200  is provided with a plug connector  203 , and a plurality of connectors  204  adapted for connection with auxiliary sensor or control means  220 . As shown in  FIG. 1   d , a plurality of the connecting modules  200  may be mounted on the base module  100  respectively, the connecting modules being provided with different types of auxiliary connectors  204 ′ and  204 ″, as desired. As shown in  FIG. 1   e , an input/output module  300  is then mounted on the first connecting module  200 , and additional input/output modules may be mounted on the remaining connecting units  200  of the assembly as best shown in  FIG. 1   f . Thus, a plurality of the field bus module assemblies  3  of the present invention may be laterally connected with the gateway  5  and power supply means  7 , as shown in  FIG. 1   f.    
   Referring now to the exploded view of  FIG. 2 , the base module  100  includes a housing  101  containing a recess  115  defused in an edge portion between the bottom wall and the associated vertical side wall. Mounted in the recess  115  are a plurality of bus bar connectors  102 , which are covered by a cover plate  103 . The connecting unit  200  includes a housing  201  having a bottom chamber in which is mounted the connecting printed circuit board  202  on which are mounted the plug connector  203  and a plurality of connecting plugs  204 . It will be seen that the plug connector  203  includes a plurality of downwardly projecting contact pins  205  that extend through the central opening of a rectangular sealing frame  206  into contact with the bus contacts  102 , as will be described in greater detail below. The plug connector  203  is connected with the printed circuit board  302  of the input/output module  300 . The input/output module  300  includes a cover member  301  having a mounting flange  304 , and the printed circuit board  302  is provided with a base plate  303  that is seated within a corresponding recess  209  contained in the upper surface of the connecting module housing  201 . 
   As shown in  FIGS. 3   a  and  3   b , the connecting unit  200  is seated downwardly upon the base module  100 , with locating pins  208  extending within corresponding locating recesses  123  contained in the base module  100 . 
   Referring now to  FIGS. 4   a - 4   c , the bottom wall of the base module housing  101  contains aforementioned the first recess  115 , and a second recess  106  that receives the bus contacts  102  and the cover  103 . Each of the bus contacts  102  includes a horizontal flat central bus bar portion  104  connected at each end to a tulip-shaped female resilient terminal  105 . The terminal  105  extend through corresponding throughbore pockets  107  for engagement by the contact ends  205  of the connecting module  200 , as will be described in greater detail below. As shown in  FIG. 4   c , the cover member  103  is spaced from the bottom edge of the base module housing  101 , thereby to define a filling chamber  110  that is completely filled with a first mass M of an encapsulating material that hermetically seals the space below the bus bar contacts  102 . 
   Referring to  FIGS. 4   d - 4   f , the upper surface of the base module  101  is provided with two rows of apertures  112  and  113  that are opposite and communicate with the resilient tulip-shaped contacts  105  of the bus bar segments, respectively. The apertures  113  are arranged in an elevated portion  121  that is provided on the laterally-projecting portion  114  of the base module housing  101 . A further row of apertures  111  is provided above the recess  115 , whereupon when a pair of modules  100  are laterally assembled as shown in  FIGS. 4   e  and  4   f , the apertures  111  extend above corresponding apertures  113  of the associated module  100 . The base module  100  is provided with a first groove  116  that extends concentrically about the raised portion  121  containing the through boreholes  113 . As shown in  FIG. 4   f , a resilient continuous seal member S is inserted within the groove  116 , whereupon when the projecting portion  114  is received within the recess  115  of an adjacent module, a sealing rib  120  ( FIGS. 4   b  and  4   c ) thereon engages and compresses the sealing member S of the first module, thereby to further protect the assembly against the invasion of moisture. 
   Referring now to  FIGS. 4   g  and  4   h , the bottom wall of the connecting module housing  201  is adapted to receive the connecting module printed circuit board  202 , with the contact pins  205  extending downwardly from the plug connector  203  on the printed circuit board. Mounted concentrically about the portion of the printed circuit board containing the pins  205  is a sealing frame  206  that is inserted within the chamber  210 , with the pins  205  extending through apertures  216  contained in the side plates of the rigid sealing frame  206 . The sealing frame is provided with a locating pin  213  that engages in corresponding positioning recess contained in the connecting housing module  201 . 
   In accordance with a characterizing feature of the invention, the sealing frame  206  is provided with a plurality of downwardly extending spacer pins  217  that engage the printed circuit board  203 , thereby to space the sealing frame  206  downwardly from the printed circuit board  202 . A second mass M′ of the encapsulating material is then inserted in the chamber defined within the hollow sealing frame  206 , with the sealing material extending outwardly between the sealing frame spacer projections  217 . The upper surface of the sealing frame  206  is provided with a groove  212  for receiving a continuous second sealing member S′. The resilient seal S′ is compressed by a corresponding rib  124  provided on the upper portion of the module  100 , as shown in  FIG. 4   e.    
   Referring now to  FIGS. 4   i  and  4   j , when the connecting module  200  is displaced downwardly relative to the base module  100 , the first row of projecting pins  205  extend downwardly into the through bores  112  for engagement with the tulip-shaped terminals  105  at one end of the bus bars  102 , respectively. The second row of contact pins  205  extend downwardly through the corresponding through bores  111  for engagement with the tulip-shaped resilient terminals at the other ends of the bus bars  102 , respectively. During this downward displacement of the connecting module  200 , the locator pins  208  extend downwardly within the corresponding guide slots  123  contained in the wall of the base module housing  101 . 
   Initially, the base module  100  is secured to a fixed support F by the fastening screw R as shown in  FIG. 4   i , whereupon the connecting module  200  and the input/output module are successively connected to define the assembly. 
   The electrically insulating sealing masses M and M′ of  FIGS. 4   c  and  4   h , respectively, are formed of a suitable castable synthetic plastic material, such as a polyurethane. 
   While in accordance with the provisions of the Patent Statutes the preferred forms and embodiments of the invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made without deviating from the inventive concepts set forth above.