Abstract:
An electric appliance ( 1 ) comprising modules ( 2, 3 ) that can be juxtaposed to one another and interconnected using bridge elements ( 4 ) for transmitting electric signals and operating voltages. The modules ( 2, 3 ) and bridge elements ( 4 ) are provided with a pair of plug-in connectors ( 31 ) and also a pair of mating plug-in connectors ( 25, 26 ). The plug-in connectors ( 31 ) are each mounted in a cylindrical outer sleeve ( 36 ), and the mating plug-in connectors ( 25, 26 ) are mounted in cylindrical ducts or penetrations ( 19 ). An O-shaped sealing ring or gasket ( 38 ) is arranged about the circumference of each outer sleeve ( 36 ), so that the O-shaped gaskets ( 38 ) are under pressure when the outer sleeves ( 36 ) are inserted in the penetration ( 19 ) to interconnect the plug-in connectors ( 31 ) and the mating plug-in connectors ( 25, 26 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electrical apparatus with juxtaposable modules which can be electrically connected to one another by bridge elements. More particularly, the present invention relates to providing reliable connections between juxtaposable modules and bridge elements using at least recesses with insertable sleeves and interposing sealing gaskets. 
     2. Description of the Related Technology 
     Prior Art apparatuses, as are known for example from DE 297 03 367 U1 are often used as subscriber devices in bus systems for control and monitoring of technical processes using sensors and actuators that can be connected to the modules via apparatus connectors. 
     To seal the connecting site between the bridge elements and the modules, in the prior art the interfitting parts are made interlocking. One such version however, due to the required production precision, dictates high production costs. Nevertheless the attainable sealing effect is poor. To improve it, therefore in the known apparatus there is an additional seal, for example, a flat seal, as is used in the apparatus known from DE 296 07 525 U1, which when the bridge elements are inserted into the modules in the insertion direction, are pressed against the bottom part of blind recesses which is used as a contact carrier in the module housing. To produce the pressure required for this purpose, in the known apparatus, there are threaded screws which are pushed through the holes of the bridge elements and can be screwed into threaded holes in the modular housing. Without this screw attachment the bridge elements, especially when these apparatuses are used on machines, would not be positionally stable and the contact-making of the connectors would not be resistant to vibrations. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to devise an electrical device of the initially mentioned type in which the connections for the bridge elements and the modules have a permenance which meets high requirements (degree of protection IP 67) in a simple and economical manner, and the disconnection force is as high as possible and vibration-resistant, and the interconnection of the connectors is ensured without additional fasteners. 
     This object is achieved by using at least recesses with insertable sleeves and interposing sealing gaskets. 
     By use of a cylindrical shape for penetrations, both economical and effective O-shaped gaskets, e.g. rings, can be used as the sealing devices; the O-shaped gaskets achieve their sealing force which acts essentially in the radial direction at a constant distance from the contact surfaces solely by their dimensions and material properties and do not require any additional features, such as more compression, or contact surfaces such as abutments. Moreover, the O-shaped gaskets can be very easily installed by being slipped onto the outside sleeves surrounding connectors or the mating connectors and do not need to be inserted into a blind recess or into grooves at the bottom part of blind recesses, as in the apparatus known from DE 297 03 367 U1. 
     In addition, the penetrations can be produced much more economically than blind recesses. Bur mainly the penetrations and the pertinent contact carriers can be located on separate parts of the electrical apparatus; this greatly simplifies both production and installation and enables versatile use. The penetrations are made either in the module housings or in the bridge elements, the pertinent contact carriers thereby independently can be included for example on circuit boards within the modules or bridge elements. 
     Furthermore, the outside sleeves which bear the O-shaped gasket are not form-fitted to the walls of the penetrations either, by which production is greatly simplified and more economical. 
     The compressing force of the gasket for appropriate selection and dimensioning of the distances of the contact surfaces is so great that forces for insertion and extraction of up to 10 kg are reached and thus in general no special additional features are necessary for sealing the attachment of the bridge elements. This has the advantage not only of a significant reduction in production and installation costs, but also easier handling, since the bridge elements, for example for replacement of modules in case of servicing, can be slipped on and withdrawn by hand. 
     By having an insertable outside sleeve integral with the bridge unit or the module housing, without additional sealing features, ensures tightness also at the insertion sites of the outside sleeve into the respective penetration. 
     By incorporation of an oblique arrangement of the contact surfaces for the O-shaped gasket, without any additional costs an increase of the insertion and withdrawal forces up to roughly 15 kg which is independent of the O-shaped gasket composition and the relevant dimensions can be achieved, because the compression force of the gasket that is directed perpendicular to the contact surfaces includes a force component arising from insertion due to the tilt of the contact surfaces. As a result of this increased withdrawal force on the one hand and the vibration-damping action of the elastic gasket on the other the resulting electrical apparatus is suited for mounting on the mounting surfaces of highly vibrating machines without additional fastening devices. 
     One version of the module housing that provides structural dimensions comparable to those of the bridge element and also includes plug-and-socket connections on the module housing for actuators, sensors and a field bus enables a very compact apparatus with a low structural height which can also be used in many applications where there is little space available for installation. 
     By way of a partition extending from the module housing with a crosspiece, provides, if necessary, support for the bridge elements slight tilting which is possible in extreme cases or in case of unintentional bumping so that for these cases reliable sealing and a high withdrawal force are achieved. The dimensions are chosen such that the cited compactness of the module housing is preserved. This embodiment can be accomplished essentially without additional costs by one-piece production. 
     Another very simple and feasible embodiment of the apparatus of the present invention, has T-shaped projections and corresponding guide slots extend from the module housing so that the modules can be attached to one another by hand (and if necessary can be detached from one another). Exact guidance of the projections into the slots moreover ensures that the center distances of the modules adjacent to the mating connectors facing one another always corresponds exactly to that of the connectors of the bridge elements, by which exactly centered axial insertion of the connectors into the penetrations and thus optimum sealing and retaining action are ensured. 
     A console-shaped execution of the module housing has the advantage that the labeling fields and display elements positioned on the oblique console surfaces are easily visible in the arrangement on or under roughly horizontal surfaces but also in a wall mounting. This is the more so when all labeling fields and display elements are located on the tilted console surface. 
     In another version of the module housing there are mounting feet extending from the module for resting on an installation surface. Between the housing bottom and the mounting surface there is a gap through which air flows (convection flow) which advantageously dissipates the lost heat released from the encapsulated modules. Compared to the prior art according to German utility models 296 07 525 and 297 03 367 in which the modules are located without spacing on the mounting sheets, the operating temperature for the present invention is lower and thus the service life of the modules is increased. 
     It is especially economical to produce the feet in one piece with the module housing, for example in an injection molding process, and to provide them at the same time with holes for screw attachment of the modules to mounting surfaces. 
     The convection flow between the housing bottom and the mounting surface and thus also the heat dissipation are especially strong when the housing bottom is made trough-shaped and to taper toward housing end faces. 
     A further intensification of cooling of the modules can be achieved incorporating elevations (domes) as part of the housing bottom in that housing bottom has a surface as large as possible for heat dissipation, for which especially tubular domes are suited for the elevations (domes). The cross sections of the domes can be made in any shape, for example, square or round. 
     A grid-like arrangement of these domes, by which corridors which run in the flow direction between the domes are formed, moreover facilitating the dissipation of unwanted lost heat. 
     A one-piece execution of the domes and housing bottom not only reduces production costs, but also ensures optimum heat transfer from the housing bottom to the dome surfaces. 
     Overall, a noticeable prolongation of the apparatus service life is achieved by incorporation at lease these features of mounting feet, housing bottom spaced from mounting surfaces, and elevations (domes) integrated as part of housing bottoms. 
     It is a good idea to use a circuit board for internal line connections and to accommodate electrical switching elements, which the board can be attached in the module housing very easily and economically by a press fit. 
     Depending on the separation of the assigned mating connectors from their penetrations, the connectors can be mounted on the circuit board and in doing so their contact elements can be connected directly to the pertinent printed conductors of the circuit board without additional connecting lines. 
     In one advantageous embodiment of the bridge elements a connector to feed an operating voltage independent of the bus lines into the modules is enabled. Conductor cross sections can thus be adapted to [the] feed currents which are desired in the individual case. For example, they can be designed for currents so high that a plurality of sensors and especially actuators can be supplied. This is not possible in the transmission of operating voltages via bus lines, for which reason for example in the apparatus known from DE 296 07 525 U1 requires an additional feed module ASI. When using bridge elements according to this embodiment of the present the invention, no such device is necessary. 
     In many applications, for individual actuators and groups of actuators separate operating voltage circuits are desired, for example when the operating voltage for certain actuators in case of a hazard is to be disconnectible on an emergency basis without influencing the remaining subscribers over the bus line. This is enabled by formation of the bridge elements by having only one conductor for the operating voltage, which bridge elements are inserted on the pertinent modules simply and economically. With these bridge elements, flexible adaptation to the different requirements of the individual case is thus achieved with respect to the operating voltage supply. Conversely, in the known apparatuses only a supply of all actuators and sensors is possible. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is explained below using one embodiment in the form of a field bus subscriber unit according to an alternative shown in the figures. 
     FIG. 1 shows a perspective view of a field bus subscriber unit according to the present invention; 
     FIG. 2 shows a perspective view of an individual module without visible mating connectors; 
     FIG. 3 shows a side view 
     (FIG. 3 a ), a plan view of the feed side 
     (FIG. 3 b ) and a plan view of the plug side 
     (FIG. 3 c ) of a bridge element; and, 
     FIG. 4 shows a section view through two modules connected to the bridge element. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A field bus subscriber unit  1 , as shown in FIG. 1, consists of the field bus terminal module  2  and four I/O (input/output) modules  3  for control and monitoring of actuators and sensors which are not shown, which are electrically connected to one another and to the field bus terminal modules  2  by internal signal and operating voltage lines via bridge elements  4 , and have plug-and-socket connections  5  for connection to the actuators and sensors. 
     The field bus terminal module  2  is connected to the field bus via two connectors  6  and on the one hand relays the sensor signals obtained from the I/O modules  3  via the internal signal lines to the field bus and on the other hand supplies control signals decoupled from the field bus via the I/O modules  3  to the actuators. 
     The I/O modules  3  have a console-shaped module housing  7  with a bottom  8  and feet  9  and a circuit board  10  which bears the plug-and-socket connections  5  which for their part pass through recesses  11  of the roof surface  12  of the module housing  7  and are somewhat flush with them. All the labeling fields  42  and LED display elements  43  of the modules  2 ,  3  are located on the console surface  13 . 
     The module housing  7  and the field bus terminal module  2  on one side wall  14  have two projections  15  which are T-shaped in cross section and in the opposite side wall  14 ′ of the I/O modules  3 , guide slots  16  which are open to the top and which are matched thereto. By inserting the projections  15  of the module housing  7  into the guide slots  16  of the adjacent module housing  7  the I/O modules  3  and the field bus terminal module  2  can be juxtaposed to one another by hand. 
     On the end face opposite the console surface  13  the module housing  7  has a shoulder  17  (see FIG.  4 ); in its base surface  18  there are two collar-shaped penetrations  19  with a cylindrical wall  20 . In the middle between the penetrations  19  of each module  3 , between the end face  21  of the shoulder  17  and a crosspiece  23  which is flush with the terminal-side end face  22  of the module housing  7  there is a partition  24 , the height of the crosspiece  23  and the partition  24  corresponds to that of the end face  21 . 
     On the circuit board  10  there are two contact carriers  25  which are not shown in FIG. 2, with twenty eight receptacles  26  each (see FIG.  4 ), which are connected to the pertinent terminal points or printed conductors of the circuit board  10  and are positioned in the area of the penetrations  19 . 
     The feet  9  which have elongated holes  27  for optionally required screw attachment of the module housings  7  project from the bottom of the housing  7  so that between the housing bottom  8  and the installation surface there is an intermediate space in which an air flow forms, by which the lost heat forming in the encapsulated  1 /O modules  3  and the field bus terminal module  2  is largely dissipated. This advantageous action is intensified by the housing bottom  8  being made trough-shaped, its tapering toward the end faces of the modules  2 ,  3  and having domes  28  which are arranged in a grid; as a result of their large surface a large amount of heat can be dissipated. 
     The bridge elements  4  each have a cuboidal housing body  29  and two 28-pin connectors provided on the base surface  30 , their center distance and that between the penetrations  19  of the two adjacent I/O modules  3 , which penetrations face one another, are the same. In two of the four bridge elements  4  there are moreover 6-pin connector sockets  33 . 
     The dimensions of the housing bodies  29  correspond to those of the space between the partitions  24  of two adjacent modules  2 ,  3  and between the crosspieces  23  and the end faces  21  of the shoulder  17 , the cover surfaces  32  being flush with the roof surfaces  12  of the module housing  7  when the bridge elements  4  are inserted. 
     The connectors  31  each consist of a carrier  35  which is integrated with a card  34  for holding the twenty eight plug pins  36  which correspond to the receptacles  26  and an essentially cylindrical outside sleeve  37  which encompasses them and which bears an O-shaped gasket  39  in the annular depression  38  of the jacket surface. 
     The inside wall  40  of the depression  38  and the penetration wall  20  parallel to it in the module housing  7  are tilted at an angle of roughly 10° to the plug axis. The tilt causes a force component in the insertion direction so that together with the corresponding dimensioning of the mutual distance of the contact surfaces  20 ,  40  and of the gasket  39  and its material properties, a high withdrawal force of roughly 15 kg is reached overall, by which installation of the field bus subscriber unit  1  is enabled even on highly vibrating surfaces, for example of machines, without additional fastening devices. 
     The connector sockets  33  each have six contact pins  42  which are held in an insulating part  41 , which are soldered on the card with continuing printed conductors, and which are encompassed by a collar  46  which projects to the outside and which is integral with the housing body  29  and the insulating part  41 . 
     In assembling the field bus subscriber unit  1 , first the field bus terminal module  2  and the I/O modules  3  are juxtaposed to one another by inserting the T-shaped projections  15  which are attached to the side walls  14  until they pass into the guide slots  16  located on the side walls  14 ′ and if necessary are screwed with the feet  9  to the installation surface. 
     In this way, the module housings  7  are detachably fastened to one another in the set position, by exact, almost play-free guidance especially the exact theoretical distance of the penetrations  19  of adjacent module housings  7 , that is, the penetrations facing one another, being aligned so that the connectors  31  cannot tilt when the bridge elements  4  are subsequently inserted into the mating connectors  25 ,  26  or cannot be inserted obliquely to the plug axes. In this way, the gaskets  38  are pressed on the entire periphery uniformly against the walls  20  of the penetrations  19 , by which the maximum sealing action is always achieved. 
     When the I/O module  3  is located on the end of the field bus subscriber unit  1  the last mating connector which is not further connected by a bridge element is covered by a blind cap  45 . 
     The internal signal lines (printed conductors on the circuit boards  10 ) which are connected to the plug-and socket connections  5  of the actuators and sensors are guided through the I/O modules  3  via the receptacles  26  of the mating connectors, the plug pins  36  of the connectors  31  and the printed conductors on the circuit board  10  and the card  34 , and are supplied to the field bus terminal module  2 . 
     Two of the four I/O modules  3  have a connector socket  33  by which the operating voltage especially for the actuators is supplied via one of the connectors  31  of the bridge elements  4  to two separate actuator circuits which each encompass two I/O modules  3  and which can thus be disconnected separately in case of emergencies. 
     The contact pins  42  of the connector sockets  33  are designed for currents of  8  Amperes (A) in this case. For their undisrupted routing to the actuators several printed conductors on the card  34  and the circuit board  10  as well as several of the thinner plug pins  36  and receptacles  26  are connected in parallel. 
     Finally, the sensors and actuators are connected to the plug-and-socket connections  5  of the field bus terminal module  2  and the I/O modules  3 , and the field bus terminal module  2  is connected to the field bus using the connectors  6 . With this simple and prompt installation the field bus subscriber unit  1  is serviceable. Replacement of modules in the field bus subscriber unit  1  of the present invention is also especially easily possible, for example in a case of service or to adapt the entire unit to altered requirements, in contrast to the apparatus unit known from DE 296 97 525 U1, regardless of the location of the individual module in the entire combination. Simply by withdrawing two bridge elements  4  (in the last I/O module  3  of the unit only one bridge element  4 ) by hand and optionally loosening the screw connections on the module feet  9  any individual module can be removed from the combination and equally promptly replaced.