Abstract:
A diaphragm valve comprises at least one valve body which has at least one inlet, at least one outlet, at least one flow channel and at least one shutoff web dividing the flow channel into channel portions. The diaphragm valve furthermore comprises a diaphragm which rests on a circumferential sealing seat of the valve body, and a drive having a drive housing, the drive being coupled to the diaphragm to press the diaphragm against the shutoff web for closing the valve. The diaphragm valve furthermore comprises a fastening unit for detachably locking the drive to the valve body, the fasting unit having a bayonet cap and an additional central retightening unit by means of which an axial tightening force is generated.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority from pending German Patent Application No. 20 2014 102 658.4, filed Jun. 6, 2014, which is incorporated herein by reference. 
       FIELD 
       [0002]    The invention relates to a diaphragm valve. The invention relates to any types of diaphragm valves having manually, pneumatically, hydraulically or electrically driven drives which usually move the diaphragm via spindles and cause an opening or closing of the valve. The drive is configured as a separate unit which is usually detachably mounted to the valve body. The diaphragm is then arranged between the valve body and the drive. 
       BACKGROUND 
       [0003]    Up to now, the diaphragm has been clamped to the valve seat such that the drive housing, for example, is fastened to the valve body by means of several screws distributed on the periphery and the diaphragm is clamped therebetween. The difficulty of this fastening consists in that the screws do not uniformly clamp the diaphragm as it is not possible to tighten all screws to exactly the same compression distance. An uneven compression of the diaphragm may however lead to a leakage between the valve body and the diaphragm and to a reduction of the service life of the diaphragm itself. Furthermore, the several screws can easily be lost during mounting or demounting of the drive or could fall into the flow channel. 
         [0004]    DE 101 53 362 A1 provides a fastening unit having a central union nut for connecting the drive to the valve body which permits a constant compression of the diaphragm. However, just in case of an overhead mounting, it is not always easy to assemble the partly heavy diaphragm valves after the valve body has usually been mounted into a drive train and possibly merely the diaphragm is to be replaced. 
         [0005]    The invention provides a diaphragm valve in which the mounting of the drive and the replacement of the diaphragm are simplified and accelerated and a uniform and process reliable diaphragm clamping is ensured. 
       SUMMARY 
       [0006]    The diaphragm valve according to the invention comprises at least one valve body which has at least one inlet, at least one outlet, at least one flow channel and at least one shutoff web dividing the flow channel into channel portions, a diaphragm resting on a circumferential sealing seat of the valve body, a drive having a drive housing, the drive being coupled to the diaphragm to press the diaphragm against the shutoff web for closing the valve, and a fastening unit for detachably locking the drive to the valve body, wherein the fastening unit has a bayonet cap and an additional central retightening unit, an axial tightening force being generated by the retightening unit and may preferably be increased in a stepless manner. 
         [0007]    In the diaphragm valve according to the invention, the drive can be very quickly mounted overhead and more specifically via the bayonet cap. A bayonet cap can however result in the parts clamped therebetween being not sufficiently compressed and in the present case the diaphragm being not sufficiently impermeable. Furthermore, a higher axial shifting force which could be obtained by a long torsional path of the bayonet cap includes the risk that the inserted diaphragm is subject to shear by the rotational movement and will suffer damage. In the invention, the bayonet cap serves to a quick fastening, and the retightening unit then ensures that the required tightening and clamping force is exerted onto the diaphragm. A central retightening unit and not numerous screws to be tightened provide for a uniform additional tightening force which is applied by the retightening unit. 
         [0008]    One embodiment of the invention provides that the retightening unit is a union nut and is thus a part that is very simple to manufacture. 
         [0009]    The bayonet cap may furthermore comprise a clamping ring having projecting claws which engage behind projections on the side of the valve body. 
         [0010]    The retightening unit can engage the clamping ring and shift the latter in the axial direction. The retightening unit and the bayonet cap are thus coupled by common parts, which reduces the required space. 
         [0011]    The retightening unit has for example a supporting face via which it is axially supported by the drive housing to press the drive housing axially towards the diaphragm. The retightening unit thus acts like a clamp in which one end is the drive housing and the other end is the valve body which is coupled to the retightening unit via the bayonet cap. 
         [0012]    The drive housing can be configured in several pieces and have an attachment housing part by which the retightening unit is supported. This means that the attachment housing part has the mating face to the supporting face. 
         [0013]    The attachment housing part not only has the function that the retightening unit can engage thereon, but also has a circumferential edge by means of which it pushes against the diaphragm and presses the diaphragm against the sealing seat. 
         [0014]    The supporting face of the retightening unit rests for example against a shoulder of the attachment housing part. 
         [0015]    If the attachment housing part is configured in a top-shaped or bell-shaped manner, the fastening of a drive spindle to the diaphragm can be accommodated in the hollow interior thereof. Usually, which is however not to be understood in a limiting manner, a coupling part which receives the spindle in a form-fitting manner is provided between the diaphragm and the spindle. 
         [0016]    It is possibly more costly to manufacture the attachment housing part with shoulders or particular surfaces. It is therefore configured as a separate part which is coupled to a main housing of the drive. This main housing is axially adjacent to the attachment housing and is connected therewith, and is however in particular configured so as to be rotatable with respect thereto. 
         [0017]    The attachment housing part and the clamping ring may be coupled to each other for joint rotation but in an axially displaceable manner by means of an axial guiding so that the bayonet cap may be detached and closed by the rotation of the attachment housing part, which permits a simple access for mounting. 
         [0018]    Furthermore, the diaphragm may be coupled to the attachment housing part for joint rotation therewith by a form-fitting, for example via one or more projecting tongues, the attachment housing part then having appropriate recesses. 
         [0019]    Furthermore, the attachment housing part has a centering for the diaphragm received therein. This can for example be obtained by an axially symmetrical centering collar. 
         [0020]    The fastening unit and the drive housing are for example configured such that the diaphragm is laterally visible at the circumference. This relevant property results in little leakages being immediately detected which is impossible in the prior art, in particular if a union nut is used. Here, the diaphragm is entirely mounted, i.e., is not visible from the outside. In contrast thereto, in the invention, it is also possible to determine the design of the diaphragm or the material of the diaphragm from the outside, for example by inscriptions at the edge of the diaphragm, which facilitates the replacing of the diaphragm in case the diaphragm last used can be identified from the outside. 
         [0021]    The bayonet cap may be a clamping ring having wing tightening claws which axially engage around a radial flange portion at the valve body so that the wing tightening claws, as seen in the radial view, have the shape of a lying “U” in which one leg is integrally formed with the clamping ring. 
         [0022]    An alternative embodiment provides that the bayonet cap is a clamping ring having radially projecting hooks which grasp mushroom-shaped holders below the mushroom head on the side of the valve seat. 
         [0023]    It must be emphasized that the diaphragm valve according to the invention is not limited to two-way valve bodies, but may of course also be used in multifunctional valve bodies including diaphragm valves having several drives and several shutoff webs. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  a first embodiment of the diaphragm valve according to the invention, 
           [0025]      FIG. 2  a second embodiment of the diaphragm valve according to the invention, 
           [0026]      FIG. 3  an explosive view of the diaphragm valve of  FIG. 1  in the region of the valve body and of the fastening of the drive housing, 
           [0027]      FIG. 4  an explosive view of the diaphragm valve of  FIG. 2  in the region of the valve body and of the fastening of the drive housing, 
           [0028]      FIG. 5  a sectional view through the diaphragm valve of  FIG. 1  in the region of the valve body and of the fastening of the drive housing, and 
           [0029]      FIG. 6  a sectional view through the diaphragm valve of  FIG. 2  in the region of the valve body and of the fastening of the drive housing. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1  shows a diaphragm valve which has several components, substantially a valve body  10  which is here configured as a two-way valve body and has an inlet  12  and an outlet  14  and a flow channel  16  connecting the inlet  12  and the outlet  14 , see  FIG. 3 , and a drive  24 . 
         [0031]    The flow channel  16  has two channel portions which begin on both sides of a shutoff web  18 . 
         [0032]    The shutoff web  18  is usually an edge of an overflow opening between the channel portions which can however optionally be closed by a diaphragm  20 . 
         [0033]    The diaphragm  20  covers an opening above the shutoff web  18  in the valve body  10  which can be seen in  FIG. 3  at reference numbers  16 ,  18 . This opening is surrounded by a flange-type annular sealing seat  22  at the valve body  10  against which the diaphragm  20  rests in a circumferentially closed manner. 
         [0034]    A drive  24  for switching the diaphragm  20  and thus the valve is represented for an upward and downward movement of the diaphragm  20 . The drive  24  is in particular a linear drive which can be operated manually, pneumatically, hydraulically or electrically. 
         [0035]    The drive  24  has an outer housing which has several parts, more specifically a main housing  26 , among other things, which is preferably cylindrical, and an attachment housing part  28  which is mounted between the main housing  26  and the valve body  10  and which is in the present case substantially configured in a bell-shaped manner. 
         [0036]    The connection between the drive housing  24  and the valve body  10  is configured as a demountable connection, namely via a bayonet cap  30  on the one hand and a retightening unit  32  on the other hand, which form together a fastening unit. 
         [0037]    The bayonet cap  30  comprises a clamping ring  34  having projecting claws, according to  FIGS. 1 and 2  so-called wing tightening claws  36  which have the shape of a lying “U” and engage behind projections on the side of the valve body, here radial flange portions  38  when they are first axially inserted into gaps  40  and are then rotated behind the flange portions  38 . Appropriate wedge surfaces ensure an axial pretensioning which is generated when the bayonet cap  30  is arrested. 
         [0038]    The clamping ring  34  rests on the inside in a centered manner on a cylindrical surface  42  of the attachment housing part  28  (see  FIGS. 3 and 5 ) and is furthermore connected with the attachment housing part  28  for joint rotation therewith but in an axially displaceable manner via axial guides, here axial projections  44  on the attachment housing part  28  and corresponding grooves  46  on the inner side of the clamping ring  34 . The attachment housing part is shifted axially downwards. 
         [0039]    A closed circumferential edge  48  on an end face of the attachment housing part  28 , here on an outwardly projecting ring flange  80  tightly presses the diaphragm  20  at the circumferential edge thereof against the sealing seat  22  (see  FIG. 5 ). 
         [0040]    The diaphragm  20  is coupled to the attachment housing part  28  for joint rotation therewith by a form-fit, more specifically by projections visible in  FIG. 3  which are configured as laterally projecting tongues  50  and are mounted in appropriate recesses  52  in the attachment housing part  28 . 
         [0041]    As is clearly visible in  FIGS. 3 and 5 , the ring flange  80  of the attachment housing part  28  has radially outside of the circumferential edge  48  a centering collar  54  which projects axially towards the diaphragm  20 , against which the diaphragm  20  rests and by means of which it is centered. The recesses  52  are provided only in the collar  54  so that the circumferential edge  48  forming a clamping face is configured without any depression. 
         [0042]    The retightening unit  32  with a union nut  62  serves to provide a fastening unit along with the bayonet cap  30  for a detachable arresting of the drive  24  to the valve body  10 . 
         [0043]    The retightening unit  32  is configured as a union nut  62  having an inwardly projecting closed circumferential ring flange  64  which rests against a shoulder  66  of the attachment housing part  28  via a supporting face  67 . 
         [0044]    The union nut  62  has an internal thread which receives an external thread of the clamping ring  34  (see  FIG. 5 ). 
         [0045]    In  FIGS. 3 and 4 , it can also be seen that the attachment housing part  28  has a sleeve projection  70  by means of which it enters the interior of the main housing  26  and serves as a guiding for a lifting spindle  72 . 
         [0046]    The lifting spindle  72  is axially displaced by the drive mechanism or manually. 
         [0047]    At the lower end, the lifting spindle  72  is coupled to the diaphragm  20  via a coupling part  74  and more specifically in a generally form-fitting manner as shown in  FIGS. 3 and 5 . 
         [0048]    The main housing  26  comprises a substantially cylindrical outer wall and a screwed-in end wall  76  which forms a guiding face for the housing attachment part  28 , more specifically a pivot bearing surface. The main housing  26  can be rotated arbitrarily with respect to the attachment housing part  28  to position the energy and/or signaling terminals in an optimum manner, for example. 
         [0049]    As can be seen in particular from  FIG. 5 , the attachment housing part  28 , the drive  24  and the fastening unit form along with the retightening unit  32  and the bayonet cap  30  a pre-mounted unit, which means that no loose parts are present when the drive  24  is to be fastened to the valve body  10 . 
         [0050]    To fasten the drive  24 , the union nut  62  is first rotated in a loose manner such that with reference to  FIG. 5 , the clamping ring  34  is rotated downwards as far as possible with respect to the attachment housing part  28 . To this end, the union nut  62  can be supported on the end face by the end wall  76 . 
         [0051]    The clamping ring  34  creeps downwards until it abuts on the end face against the ring flange  80  of the attachment housing part  28  which projects outwards like a shoulder. In this position, the drive  24  is placed onto the valve body  10 . By the engagement on the wing tightening claws  36  for example, the bayonet cap  30  is then closed, the claws  36  being easily inserted into the radial flange portions  38  by oblique surfaces which slide onto each other. The retightening unit  32  is then actuated by rotating the union nut  62 . By the support by the shoulder  66 , the union nut  62  pulls the axially guided clamping ring  34  upwards, i.e., towards the drive  24  so that the clamping force is increased uniformly and centrally by one single actuation or, in other terms, the attachment housing part  28  is pressed axially downwards. 
         [0052]    As is in particular visible in  FIG. 1 , the diaphragm  20 , more specifically the circumferential edge thereof is visible laterally from the outside in the region of the clamping in the fastened state so that leakages are immediately detectable. 
         [0053]    The embodiment according to  FIGS. 2 ,  4  and  6  substantially corresponds to the just described Figures,  FIG. 2  being the view corresponding to  FIG. 1 ,  FIG. 4  being the view corresponding to  FIG. 3 , and  FIG. 6  being the view corresponding to  FIG. 5 . The already introduced reference numbers are again used for identical or functionally identical parts so that only the differences are explained below. 
         [0054]    In the embodiment of  FIGS. 2 ,  4  and  6 , the valve body  10  is a multifunctional valve body having several inlets and/or outlets. This valve body  10  is also coupled to the drive  24  via a fastening unit having a bayonet cap  30  and a retightening unit  32 , and in this respect, there is in principle no difference. 
         [0055]    In this embodiment, the bayonet cap  30  is however configured in a different manner. Here, the clamping ring  34  has claws in the form of hooks  90  which project radially at one end and form forks  92  open on one side in the circumferential direction. Mushroom shaped holders  94  are present at the valve body  10  in one piece or by their own parts which can be molded screws, for example. 
         [0056]    In this case, the drive  24  is also placed onto the valve body  10  along with the fastening unit mounted thereon, and the clamping ring  34  is then rotated such that the holders  94  enter the forks  92  with their mushroom heads. The fastening unit is then further axially pretensioned by the retightening unit  32  to clamp the diaphragm  20  at the circumference. 
         [0057]    The diaphragm  20  is also visible on the circumferential side in this embodiment. 
         [0058]    It must be emphasized that the different valve bodies  10  and bayonet caps  30  may of course arbitrarily be combined with each other.