Plug connection for aquarium pressure medium conduits
This is a continuation application of Ser. No 252,445--Panthofer, filed Apr. 9, 1981, now abandoned. 
    
    
     The present invention relates to a plug connection for aquarium pressure medium conduits, particularly in connection with aquarium filter devices, such as external filter connections, and comprises a plug, and a sleeve for receiving this plug. 
     Aquarium conduits generally are very critical because, if handled in an inexperienced or unprofessional manner, they can cause damage to the aquarium and/or its contents, and because the servicing of aquariums is primarily handled by inexperienced individuals or by children. Additionally, these conduits are particularly critical if they are used in connection with so-called external filters, in which case they are mostly under an overpressure. 
     It is an object of the present invention to embody the aforementioned connections in such a manner that they can be operated under pressure without having to fear that water will leak or flow out. 
    
    
     This object, and other objects and advantages of the present invention, will appear more clearly from the following specification in connection with the accompanying drawing, which is a vertical section through one embodiment of an inventive elbow-type plug and an associated sleeve, with the plug and sleeve being aligned one above the other. 
    
    
     The plug connection of the present invention is characterized primarily in that both the plug and the sleeve are provided with a valve disc or plate which blocks a conduit while being subjected to a spring pressure; the axially displaceable shafts of the valve discs, during coupling or plugging together, come into abutment with each other. Furthermore, the housing of the plug and of the sleeve can be plugged together in such a manner that, in assembled condition, they form a pressure-tight conduit between the two valve discs. 
     Accordingly, each of the two structural elements necessary for the formation of the plug connection, namely the plug and the sleeve, includes its own valve by means of which the pressure medium conduit can be blocked. 
     However, when the two structural elements are plugged together, both valves open, thus letting the fluid flow through, while the housing of the sleeve and of the plug again form a pressure-tight or liquid-tight connection. 
     Consequently, the conduits of an aquarium which are under pressure can be separated from each other and reunited while being under pressure. 
     To assure a good guidance of the valve discs, they have preferably shafts associated therewith which are arranged coaxially with respect to the discs. These shafts can be guided so that with a longitudinal movement of the shafts, there can occur a corresponding movement of the valve discs. 
     According to specific preferred embodiments of the present invention, the shafts are so dimensioned that when plugging together the sleeve and the plug, they abut upon each other prior to lifting off of the valve discs from their sealing seats. The two shafts in such case positively fit into each other with their free ends. One shaft may have an essentially conical recess or depression, and the other shaft may have a correspondingly shaped conical free end. 
     Each of the valve discs and their shafts may be provided with a central bore into which a pin mounted on the pertaining housing encages or projects in such a way that the valve discs and the shafts are longitudinally guided. The valve springs may surround the pins. 
     The valve discs may each have an inclined seating surface which engage sealing rings located in grooves of the housings. 
     The plug, in the assembled or plugged-together condition, may with its end face engage an abutment surface of the housing of the sleeve. 
     The front part of the housing surrounding the shaft of the plug may be provided with a seal in the region of its free edge, with this seal sealingly engaging the inner surface of a bore in the sleeve corresponding in shape to the free end of the plug housing. 
     The sleeve may be located in a hole or bore of a filter housing wall in partially countersunk arrangement, and the plug is preferably embodied as an elbow or angle plug. 
     Referring now to the drawing in detail, the upper portion shows an elbow type plug 1, the upper rear part of which is provided with a horizontally projecting spout 2 for receiving a hose or tube 3 which leads to a pressure pump located inside the aquarium. 
     The sleeve 4, illustrated in the lower portion of the drawing, is, on the other hand, inserted in a wall 5 of a pressure-tight filter housing. 
     The sleeve 4 and the plug 1 have respective upwardly and downwardly directed pins or studs 6, 6&#39;, which are arranged coaxially of the two housings 7,7&#39;, the fronts of which are essentially tubular in shape. The pin 6 of plug 1 is fastened to the upper transverse wall 8 of the housing 7, and the pin 6&#39; of sleeve 4 is mounted in a cage 9 which is formed by arms 10 for passage of water therethrough. 
     Longitudinally guided on the pins 6,6&#39; are the valve discs 11, 11&#39;, respectively associated with the plug 1 and the sleeve 4, with bores 12, 12&#39;, and the pertaining hollow shafts 13, 13&#39;. 
     Compression springs 14, 14&#39; located on the pins 6,6&#39; act on the valve discs 11, 11&#39; in such a manner that their inclined seating surfaces 15, 15&#39; are pressed against respective sealing rings 16, 16&#39; located in annular grooves 17, 17&#39; of the housings 7,7&#39;. The compression springs 14, 14&#39; thus assure valve closure. The passage of water is therefore not possible when the sleeve 4 and the plug 1 are separated. 
     Shaft 13 of plug 1 has at its free end a conical tip 19; the free end of shaft 13&#39; of sleeve 4 has a corresponding conical recess or depression 18 which matches the conical tip 19 of shaft 13. Additionally, the free end of shaft 13 of plug 1 projects out of the housing 7 by a distance a. The length of shaft 13&#39; of sleeve 4 is so dimensioned that, upon plugging together of plug 1 and sleeve 4, the conical tip 19 of shaft 13 engages over its entire surface in the recess 18 of shaft 13&#39; after the sealing ring or seal 20 of plug 1, which seal is located externally of the free end of the housing 7, has already come into engagement along the inner surface 21 of sleeve 4. Only after this sealing connection has been established, does there occur, during further plugging together of sleeve 4 and plug 1, a displacement of the shafts 13, 13&#39; against the spring force. The thus resulting lifting of the valve discs 11, 11&#39;, and the opening of the valves, thus occurs only after the formation of a pressure-tight passage through the tubular shaped parts of the housing 7,7&#39; facing each other. In plugged-in condition, the end face 22 of plug 1 then rests on the abutment surface 23 of sleeve 4. 
     The plug 1 is pulled out for releasing the connection, for instance for the purpose of cleaning the filter. The valves then close due to the spring force; this closing of the valves takes place before separation of plug 1 and sleeve 4 is completed. 
     The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawing, but also encompasses any modifications within the scope of the appended claims.