Abstract:
A securing element ( 26 ) for securing against the loosening by rotation of at least two screwable housing parts ( 3,2 ), the securing element ( 26 ) being arranged so as to be clamped in one of the housing parts ( 3 ) and interact with the other housing part ( 2 ).

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an element for securing at least two housing parts, which can be screwed together, against unscrewing. 
     In pipeline construction, various housing parts are screwed together. For example, in the case of a diaphragm valve, the diaphragm is fixed between two housing parts which can be screwed together. It is necessary to be able to open the housing parts in the course of the operating time in order to change the diaphragm. As the clamping of the diaphragm weakens, it is necessary to be able to tighten up the housing parts with respect to each other. During operation of the diaphragm valve, the housing parts should be secured against unscrewing. 
     On the basis of this prior art, it is an object of the invention to specify an element for securing against unauthorized unscrewing, this element being arranged as integrally as possible in the housing parts and such that it is not visible from outside. 
     SUMMARY OF THE INVENTION 
     The object is achieved by an element for securing at least two housing parts, which can be screwed together, against unscrewing, wherein the securing element is arranged in a clamping manner in one of the housing parts such that it engages with the other housing part. 
     It is advantageous for the diaphragm valve to be secured against unauthorized removal. This is achieved by a securing element being arranged in a clamping manner in the lower housing part. The securing element is arranged between the lower housing part and the external housing of the upper housing part, wherein the securing element has a resilient region having an outwardly facing toothing. The external housing has an inwardly facing further toothing, which engages with the toothing of the securing element, wherein the toothings have two different flank angles, such that the resistance of the housing parts to unscrewing is greater than to tightening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An exemplary embodiment of the invention is described with reference to the figures, in which: 
         FIG. 1  shows a side view of a valve housing of a diaphragm valve, 
         FIG. 2  shows a perspective view of an element for securing the diaphragm valve, 
         FIG. 3  shows a section through the valve housing with the securing element, 
         FIG. 4  shows an enlargement of a region of  FIG. 3  with the securing element, and 
         FIG. 5  shows an enlargement similar to  FIG. 4  with the arrangement in the screwed-together state. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a side view of an external housing  13  of an upper housing part  2 , and a lower housing part  3  of a diaphragm valve  1 . A securing element  26  is clamped in the lower housing part  3  with an exact fit and secured against unscrewing. The securing element  26  is arranged in the region of a ledge  30 , which acts during screwing-together as an abutment on the lower housing part  3  for the lower edge of the external housing  13 . The exact fit and unrotatable arrangement of the securing element  26  are achieved by the formation of two shoulders  31 ,  32 , which fit into a corresponding recess in the lower housing part  3 . The securing element  26  can be changed if necessary. In  FIG. 1 , the diaphragm valve  1  is illustrated in the completely screwed-together state. 
       FIG. 2  illustrates the securing element  26  separately in perspective. The securing element  26  has a resilient region  27 , which is arranged in parallel with the spindle axis of the diaphragm valve  1  and can spring perpendicularly to the spindle axis. The securing element  26  has outwardly facing tooth flanks  28 ,  29 , which engage with further, inwardly facing tooth flanks (not illustrated here) on the inside of the periphery of an external housing  13  of the upper housing part  2 , which are designed to be complementary to one another. The tooth flanks  28 ,  29  have substantially different flank angles. The result of this is that the force applied for loosening the screwed connection is much greater than the force required for screwing together. The resilient region  27  is arranged inside the external housing  13  and is barely visible, or not visible, from outside the diaphragm valve  1  in the screwed-together state. 
       FIG. 3  illustrates a section through the securing element  26  together with the lower housing part  3  and the external housing  13  of the upper housing part  2 .  FIG. 3  shows the state when the upper housing part  2  and the lower housing part  3  of the diaphragm valve  1  start to be screwed together. The screwing of the upper housing part  2  to the lower housing part  3  can be tightened up with increasing deformation of the diaphragm. The securing element  26  prevents unauthorized opening or unscrewing of the diaphragm valve  1 . 
       FIGS. 4 and 5  illustrate enlargements of the screwing arrangement.  FIG. 4  is an enlargement from  FIG. 3  and illustrates the state when screwing together starts and  FIG. 5  illustrates the state when screwing together ends. 
     In order to increase the closing force, a plurality of securing elements  26  can also be arranged distributed around the periphery of the valve housing. The securing element  26  can also be used for valve types other than the diaphragm valve  1  or else for other elements of a pipeline system, for example union nuts, wherein two housing parts are screwed together and must be secured against unauthorized unscrewing.