Abstract:
A membrane valve for fluid media, comprising a valve body, a membrane, a pressure piece, and a drive) for the pressure piece. The membrane is coupled to the pressure piece by a connecting element, having a wall which projects from the membrane in the direction of the pressure piece. A latching hook laterally protrudes from one side and a free space is provided on the other side such that the wall. The latch hook can be deflected in order to connect the latching hook to a corresponding receiving portion on the pressure piece. A stationary pin engages into the free space when the membrane is raised from the valve seat of the valve body and protrudes out of the free space when the membrane is resting on the valve seat.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a National Stage of International Patent Application No. PCT/EP2013/072665, filed on Oct. 30, 2013, which claims priority to and all the benefits of German Patent Application No. 10 2012 222 062.3, filed on Dec. 3, 2012, both of which are hereby expressly incorporated herein by reference in their entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a membrane valve, particularly for fluid media, having a valve body, a membrane, a pressure piece and a drive for the pressure piece, wherein the membrane is coupled to the pressure piece by of a connecting element, wherein the connecting element comprises a wall projecting from the membrane in the direction of the pressure piece, wherein a laterally projecting latch hook is provided on one side of the wall and on the other side is provided a free space, so that the wall can get out of the way for connecting the latch hook with a corresponding receptacle. 
     2. Description of the Related Art 
     There are known membrane valves that have a valve body having an inflow and an outflow (DE 20 2005 002 152 U1). Furthermore, the valve bodies comprise a valve seat sealable by a membrane, wherein the membrane is connected by a connecting element with a pressure piece of a drive. The known membranes can be made in one or two layers. From WO 2010/025 905 A1 is known a single-layer membrane, which may also be formed integrally with the connecting element or on which can be formed the connecting element. The membrane is made of the same plastic material as the valve body, namely of polyethylene (PE). In addition, the valve body and the membrane are connected fixedly to each other by ultrasonic welding in a fluid-tight valve body unit which can be coupled with the drive. 
     Due to the fixed connection of the valve body, the membrane and the connecting element to a sealed valve body unit, it is possible to form the valve body unit as a disposable unit, and to integrate the membrane valve into a disposable hose system or pre-sterilizable pharmaceutical system. The valve body unit can therefore be formed in a cost-effective way as a disposable or single-use valve body unit and be coupled to a reusable drive or connected to it. The firm connection of the membrane and the valve body seals the valve body unit during the transport phase. This avoids contamination of the valve chamber or the environment. 
     Due to the firm connection of the connecting elements with the membrane, the membrane can not only be pushed into its closed position but also pulled into its open position, so that the valve chamber in the valve body can be designed to be relatively large in volume and thereby, for example, a sufficiently large volume flow can be achieved for the tube systems of filtration equipment. However, it has turned out that the achievable lift between the closed and open positions is limited, because otherwise the coupling of the pressure piece and the connecting element is unintentionally released as the connecting element disengages due to too high pressure. 
     SUMMARY OF THE INVENTION 
     The invention is therefore based on the technical task to provide a membrane valve in which the membrane can perform a greater lift without the risk that the connecting element and thus the membrane decouples from the pressure piece. 
     This technical task is solved in a membrane valve of present invention, in that a fixed pin is provided which, with the valve seat of the valve body lifted off the membrane, engages into the free space behind the wall and, particularly in the case of the membrane resting on the valve seat, protrudes from the free space. 
     In the membrane valve according to the invention, the membrane is connected by a latch hook to the pressure piece, so that the coupling easily occurs in that the connecting element is snapped together with the membrane on the pressure piece. When closing the membrane valve, this type of connection does not pose any danger. If the membrane valve is opened, the membrane of the pressure piece is lifted by the connecting element from the valve seat by applying a pull to the connecting element. However, a simple snap-in connection can be released unintentionally. In the inventive solution, this is prevented in that the wall which carries the latch hook cannot get out of the way because of the pin that is present in the free space, and thus the latch hook cannot come out of its seat in the receptacle. This allows much higher tensile forces to be exerted on the connecting element and the membrane to be removed from the valve seat. 
     One embodiment of the invention provides that the connection element is formed cup-shaped and the opening is in the direction of the pressure piece. Thereby, the forces acting on the connecting element can be easily distributed over the circumference. The connecting element is designed in the manner of a hollow locking pin. 
     In a further development of the membrane valve according to the invention, the cup-shaped connecting element comprises a circular cylindrical pin, wherein on its outer circumference is or are arranged the latch hook(s). Advantageously, the pressure piece is surrounded by a fixed sleeve in which the pressure piece can be moved. The sleeve thus forms a sliding sleeve for the pressure piece. 
     In one embodiment, a transverse pin is mounted in the sleeve. This transverse pin is stationary as the sleeve itself. For receiving the transverse pin, the pressure piece comprises a breakthrough transverse to its direction of movement, which is penetrated by the transverse pin. In addition, the stationary pin is mounted on the transverse bolt. The stationary pin in turn passes through the pressure piece in its direction of movement and in the direction of the membrane. In this way, inside the displaceable pressure piece is a stationary element, which cooperates with the cup-shaped connecting element and in particular engages in it. 
     The free end of the fixed pin is formed in such a manner that, with the membrane lifted from the valve, it engages in the cup-shaped connecting element and bears against the inner surface of the wall. In this way, a shift of the wall is prevented so that the latch hook does not disengage from the receiving recess even under high tensile forces. With the membrane resting on the valve seat, only when the free end of the fixed pin emerges from the cup-shaped connecting element, the connecting element and thus the membrane can be decoupled from the pressure piece and, for example, exchanged. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages, features and details of the invention become clear from the dependent claims and the following description in which one embodiment is described in detail with reference to the drawing, wherein: 
         FIG. 1  is a side view of a membrane valve with a drive, partially cut open; 
         FIG. 2  illustrates the membrane with an integrated connecting element in side view; 
         FIG. 3  illustrates the membrane of  FIG. 2  in cross-section; 
         FIG. 4  is an enlarged illustration of the pressure piece with attached membrane with the membrane valve closed; and 
         FIG. 5  is an enlarged illustration of the pressure piece with attached membrane with the membrane valve open. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a membrane valve generally indicated at  10  in which a valve body  20  is attached to a drive  14  by a clamp  12 . The drive  14  may include an electrically, hydraulically or pneumatically operated drive unit  16  and an adapter  18 . The valve body  20  is equipped with a membrane  22  with a connecting element  24 , which is shown in  FIGS. 2-5  in detail. The valve body  20  has an inflow  26  and an outflow  28 , which opens into the valve chamber  30  limited between the valve body  20  and the membrane  22 , wherein the connection between the inflow  26  and the outflow  28  is interrupted by pressing the membrane  22  against a valve seat  32 . 
     The membrane  22  is supported on a projecting shoulder  34  of the valve body  20  which protrudes over the valve seat  32  and seals the valve body  20  relative to the drive  14  and the environment. In the embodiment illustrated herein, the valve body  20  is formed of polypropylene (PP), and the membrane  22  of a thermoplastic elastomer (TPE). Other materials and material combinations are possible and the invention is not limited to the aforementioned materials. 
     On its back side  35  facing away from the valve body  20 , the connecting element  24  is coaxially connected with the membrane  22  and project from the membrane  22 , in particular integrated by a 2-K injection molding process, having a greater width than the valve seat  32 . With the membrane valve  10  closed, the membrane  22  is formed convexly toward the valve seat  32 , wherein the corresponding valve seat  32  is also formed convexly toward the membrane  22 . The membrane  22  and the valve body  20  are connected to each other liquid-tight and gas-tight, in particular by ultrasonic welding, in the region of the shoulder  34 . 
     The drive unit  16  has a substantially cup-shaped housing  36  with an adjusting spindle  38  movable in its longitudinal direction. The housing  36  can be put in a known manner from the inside, for example, on a control cabinet plate  40  and fastened from the outside by the adapter  18 . On the free end  42  of the adjusting spindle  38  is screwed a pressure piece  44 , whose free end in turn can be latched and unlatched with the connecting element  24 . 
       FIGS. 2 and 3  show the membrane  22  with integrated connecting element  24 . It can be clearly seen that the connecting element  24  is formed with a first section  46  in a mushroom-shape and a concave free end  48 . The concave end  48  is mounted in the cone-like manner in the convex section of the membrane  22  so that in the membrane  22  is formed a lenticular material accumulation in the area of the concave end  48  of the connecting element  24 . This achieves an optimal power transmission by the connecting element  24  to the membrane  22 , especially when opening the membrane valve  10 , i.e. when lifting the membrane  22  from the valve seat  32 . The concave end  48  of the connecting element  24  has an encircling peripheral edge, semi-circular in cross-section, so that notch effects in the material of the membrane  22  are avoided. 
     The second region  50  of the connecting element  24  facing away from the membrane  22  is formed cup-shaped and as a locking pin  52  which serves for fastening the connecting element  24  on the pressure piece  44 . For this purpose, the locking pin  52  comprises axial slots  54 , whereby a total of three walls or fingers  56  are formed, which are provided at their free ends with locking lugs  58  which project radially outward. In addition, the locking pin  52  is formed hollow as a hollow pin  59 . The locking lugs  58  have a distal insertion bevel  60  and a proximal shoulder  62  for locking in the pressure piece  44 . The pressure piece has a receiving bore  63  ( FIG. 5 ), into which the locking lugs  58  enter when the membrane valve  10  is closed for the first time and snap into the provided undercuts. The force required for engagement is low due to the relatively elastic finger  56  and the inlet slopes  60 . However, the pull-off force is high because the shoulders  62  optimally anchor the locking pins  52  in the pressure piece  44 . 
       FIG. 4  shows the locking pin  52  locked in the pressure piece  44 , whereby the membrane valve  10  is in its closed position, i.e. the pressure piece  44  is extended so that the membrane  22  rests on the valve seat  32 . 
     Furthermore, it is apparent that a sliding sleeve  64  is arranged in the adapter  18 , which sleeve is located coaxially to the axis of the pressure piece  44  in which the pressure member  44  is displaceable. This sliding sleeve  64  is provided with a transverse bore  66  in which a cross-bolt  68  is mounted. This cross-bolt  68  also passes through the pressure piece  44  in its breakthrough  70  extending transverse to its direction. Finally, in the pressure piece  44  is provided a coaxial bore  72 , in which is mounted a sliding pin  74 , whereby the pin  74  is also penetrated by the cross-bolt  68 . The sliding sleeve  64 , the cross-bolt  68  mounted therein and the pin  74  mounted on the cross-bolt  68  are stationary relative to the pressure piece  44 , i.e. they do not perform the displacement movements of the pressure piece  44 . This has the result that during the opening operation of the membrane valve  10 , in which the membrane  22  is lifted from the pressure piece  44 , the pin  74  remains above the locking pin  52  and the locking pin  52  comes closer to the pin  74  and finally the pin  74  engages in the cup-shaped locking pin  52 . 
     This position of the locking pin  52 , which it occupies in the open position of the membrane valve  10  is shown in  FIG. 5 . The sliding movement of the pressure piece  44  and the coupled locking pin  52  is not impeded. Since to open the membrane valve  10 , tensile forces are exerted by the pressure piece  44  on the locking pin  52 , normally, there is the danger that the locking pin  52  disengages from the pressure piece  44  in that the walls or fingers  56  bend radially inward and the shoulders  62  of the locking lugs  58  come free from the undercuts in the pressure piece  44 . This is prevented in the invention by the pin  74  engaging with the locking pin  52 , because now the finger  56  can no longer move away. The locking pin  52  is secured to the pressure piece  44 . 
     The engagement of the pin  74  starts from a lift height of 1.8 mm. Since the pin  74  at the extended pressure piece  44  does not engage the locking pins  52 , a change of the membrane  22  is no problem, because the walls or fingers  56 , the fingers  56  can be freely disengaged from undercuts in the pressure piece  44  bent radially inward and. It can be transmitted to the membrane  22  so much higher tensile forces. 
     The engagement of the pin  74  starts from a lift height of approximately 1.8 mm. Since with the extended pressure piece  44  the pin  74  does not engage in the locking pin  52 , an exchange of the membrane  22  is no problem, because the walls or fingers  56  are bent radially inward and the fingers  56  can be freely disengaged from the undercuts in the pressure piece  44 . There can thus be transmitted so much higher tensile forces to the membrane  22 . Another advantage is seen in the fact that, since in the adapter  18  (or the spacer) the sliding sleeve  64  is used as a separate component, the membrane valve  10  can be easily mounted. Furthermore, the sliding sleeve  64  serves for exact and frictionless guiding of the pressure piece  44 . A locking of the locking pin  52  is thus guaranteed even with a slanting membrane valve  10  with deviations at which the locking pin  52  may also lie eccentrically or the locking pin  52  is slightly out of round. 
     The valve body  20  can be used as a single-use valve body unit, for example in sterile pharmaceutical clean rooms or in the food industry. As a reusable valve body  20 , it may be used in any conceivable area in which plastic valves can also be used. 
     The invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.