Abstract:
The invention relates to a valve particularly for transferring small portions of glue onto folding tabs of (cigarette) packs. A closing element ( 15 ) of the valve is actuated by different elements, that is to say, is moved between the open and closed positions, on the one hand by two permanent magnets ( 24, 25 ) arranged a short distance from each other and having aligned poles such that the closing element is permanently kept in the closed position by the permanent magnets ( 24, 25 ). On the other hand, an actuating element, which is configured as an electromagnet ( 23 ), acts to move the closing element ( 15 ) into the open position in a controlled way by overcoming the closing forces. The closing element ( 15 ) is designed in a particular way, that is to say, with channels extending along the outside in the longitudinal direction for the medium or the glue.

Description:
STATEMENT OF RELATED APPLICATIONS 
     This patent application claims the benefit of Patent Cooperation Treaty International Application No. PCT/EP2008/004933 having an International Filing Date of 19 Jun. 2008, which claims priority on German Patent Application No. 10 2007 029 064.2 having a filing date of 21 Jun. 2007, both of which are incorporated herein in their entireties by this reference. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The invention relates to a valve for fluid media, particularly a glue nozzle or glue valve, having a valve housing, a discharge or valve opening, and a closure element which is movable within the valve housing and which, with an end-sided closing piece, when the valve or nozzle is closed, is held in sealing contact against a valve seat or nozzle seat, wherein the closure element can be moved within the valve housing by an actuating means, in particular by an electromagnet, into an opening position and by permanent magnets into a closing position, and the magnetic force or magnetic field strength which acts in the closing position of the closure element is weaker than the opening force of the actuating means which acts upon the closure element. 
     2. Prior Art 
     Glue nozzles or glue valves are geared to dispensing small portions of glue at a very high cycle rate. In a known glue nozzle, an elongated closure element with cone-shaped closing piece can be moved within the valve housing by an electromagnet into an opening position and by a helical spring into the closing position respectively (EP 0 719 592 A2). In the event of a long operating period and a high number of cycles of opening and closing motions, the closing element configured as a preloaded spring is unsatisfactory. 
     BRIEF SUMMARY OF THE INVENTION 
     The object of the invention is to propose a valve or a nozzle, in particular for the transfer of glue portions, that is designed for a long working life combined with high cycle rates and, moreover, is capable of delivering very exact, small (glue) portions. 
     For the achievement of this object, the valve according to the invention is characterized by the following features:
     a) a first permanent magnet is arranged within the valve housing on a fixed support and a second permanent magnet is arranged opposite thereto, and with aligned magnetic pole, on the closure element,   b) the permanent magnets configured with somewhat smaller transverse dimensions are embedded in the support on the one hand and in the closure element on the one hand, such that the aligned magnetic poles of the two permanent magnets are facing each other.   

     The valve according to the invention is hence configured such that a motional cycle of the closure element is realized by the interaction of two permanent magnets, to be precise particularly a closing motion. For opening, a suitable actuating element, particularly an electromagnet, acts counter thereto. 
     A further particularity consists in the fact that the closure element in the opening position is held in contact against a fixed stop part of the valve or valve housing, spacers ensuring that the elements or permanent magnets are spaced at a short distance apart for the protection of the mutually facing permanent magnets. 
     The closure element is specially configured. An elongated closure body, in particular in a substantially cylindrical construction, has on the periphery longitudinally running depressions, channels or the like, which allow the passage of the medium, in particular the glue, along the shell surface of the closure body. Projections or ribs of the closure body serve to bear against an, in particular, cylindrical inner face of the valve housing. The spacers are also preferably arranged on the closure body. 
     A further particularity is the configuration of the valve seat. This consists of a mount, in particular of metal or stainless steel, detachably inserted, in the housing, and a nozzle body, of particularly hard-wearing material, in particular, ceramic, inserted in this mount. This nozzle insert is preferably connected to the mount by gluing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and particularities of the valve according to the invention are explained in greater detail below with reference to the description of illustrative embodiments, wherein 
         FIG. 1  shows a (glue) valve in vertical section, 
         FIG. 2  shows a detailed feature II of the valve according to  FIG. 1  on an enlarged scale, 
         FIG. 3  shows the valve according to  FIG. 1  in a view according to the arrow III, on an enlarged scale, 
         FIG. 4  shows a detail of the valve in horizontal section, likewise enlarged, 
         FIG. 5  shows a representation, analogous to  FIG. 4 , of the illustrative embodiment according to  FIG. 2  in the sectional plane V-V, 
         FIG. 6  shows a representation of the valve, analogous to  FIG. 1 , with additional elements, 
         FIG. 7  shows the illustrative embodiment according to  FIG. 6  in a sectional plane or top view VII-VII according to  FIG. 6 , 
         FIG. 8  shows a detail of the valve in perspective representation, namely a nozzle insert, 
         FIG. 9  shows the detail according to  FIG. 8  in a another view, likewise in perspective, 
         FIG. 10  shows a closure element as a detail of the valve, in perspective. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The shown illustrative embodiments relate to a valve or a nozzle for flowing media. This is primarily used as a glue valve in packaging technology for transferring small portions or spots of glue onto support material, in particular onto folding tabs of cigarette packs. 
     The glue valve consists of a valve housing  11 , to which the medium, i.e. glue, can be fed via a glue line  12 . The glue portions are discharged from a (lower) valve opening  13  or nozzle opening, which is delimited by a conical or cone-shaped valve seat  14 . Interacting with the latter is a movable closure element  15 , which is provided with a closing body facing the valve seat  14  or the valve opening  13 , or with a spherical closing piece  16 . This is held in sealing contact against the conical valve seat  14  when the valve opening  13  is closed. The closing piece  16  is connected by an intermediate piece  17  to a plunger piece  18  as part of the closure element  15 . The plunger piece  18 , and thus the closure element  15  as a whole, can be moved back within the valve housing  11  in the direction of the valve seat  14 . Above the valve seat  14  a valve chamber  19  is formed, into which the glue line  12  emerges and from which, when the valve is open, glue is discharged via the valve opening  13 . 
     The valve housing  11  is provided with a continuous inner space  20 , which on the side opposite to the valve opening  13  is open and is round in cross section. Said inner space is closed off by a closure piece  21 , which is arranged adjustably in a fixed position within the valve housing  11 . The closure piece  21  serves, at the same time, as a stop for the closure element  15 , which latter can be moved to and fro (out and down). 
     The closure element  15  can be moved by a closing element into a closing position and by an actuating element into an opening position. The closing element is preferably constantly active, so that the closing position of the valve or of the closing piece  16  is the normal setting. The return element for moving the closure element  15  into the opening position is an electromagnet  23 , which surrounds the closure element  15  at least in a part-region. The metallic plunger piece  18  of magnetizable metal acts within a coil of the electromagnet  23  as its core. When current is supplied, a magnetic force is hence transmitted to the plunger piece  18  and thereby moves the closure element  15  as a whole into the opening position. 
     The closure element  15  is preferably permanently urged in the direction of closing by a closing means. This is configured as a permanent magnet, which applies a permanent magnetic force to the closure element  15  for the purpose of a closing motion. The permanent magnet consists of two single magnets  24 ,  25 , of which one is fixedly attached to the valve housing  11  and the other to the closure element  15 . In the present case, a single magnet  24  is attached to the end region of the closure piece  21 , to be precise in the region of an end face which faces the plunger piece  18 . The single magnet  24  is seated in a recess or depression in the end region of the closure piece  21 , to be precise slightly set back from the end face or front face of the closure piece  21 . The single magnet  24  is thereby protected ( FIG. 2 ). 
     Analogously, the other single magnet  25  is attached to the (upper) end of the closure element  15  or of the plunger piece  18 , or is embedded in a corresponding recess. The single magnets  24 ,  25  are hence spaced at a (short) distance apart, even when the glue valve is open. The stroke motions of the closure element  15  lie within a limited range from 0.2 mm to 0.8 mm, in particular in a range from 0.2 to 0.5 mm. An optimal stroke length is 0.3 mm. 
     The mutually adjacent permanent single magnets  24 ,  25  are positioned such that the same poles are facing each other, for example the North poles ( FIG. 2 ). A repulsive force is thereby transmitted by the permanent single magnets  24 ,  25  to the closure element  15 , so that this is urged in the closing position. The opening motion by the electromagnet  23  overcomes this permanent closing force. 
     The electromagnet  23  or its winding is arranged in an insert  28 , which in vertical or axial section forms a U-shaped, circumferential recess for the winding of the electromagnet  23 . The insert forms a cylindrical part of the valve chamber  19 . The electromagnet  23  extends in a region such that the two single magnets  24 ,  25  and a part-region of the closure element  15  are also embraced. 
     The closure element  15  is specially configured. The plunger piece  18  is tailored to the shape and dimension of the inner space or of the valve chamber  19  in the region of a cylindrical guide part  34 . The closure element  15  is configured such that, between it and a (cylindrical) inner face  35  of the valve housing  11 , defined spaces for the passage of medium, in particular glue, are formed. The glue can hence enter into the region between the closure element  15  and the valve housing  11  or guide part  34 , as far as the closure piece  21 . For this purpose, channels, grooves or similar flow paths for the medium are formed on the periphery of the closure element  15  in the region of the plunger piece  18 . In the preferred illustrative embodiment, flow channels  36  are formed all the way round and with even distribution. These extend over the full length of the plunger piece  18 , i.e. as far as an end face which faces the closure piece  21 . Between the several flow channels, supporting or guide elements, in particular rib-like projections  37 , are formed, which effect a guidance or contact of the closure element  18  against the inner wall of the valve housing  11 , so that the closure element  15  is exactly centered within the cylindrical part of the valve housing  11 . 
     In the illustrative embodiment according to  FIG. 4 , the laterally directed rib-like projections  37  are polygonally configured, having a central supporting surface. The flow channels  36  which are thereby formed or delimited are correspondingly polygonally configured on the inner side. In the illustrative embodiment according to  FIG. 5 , the flow channels  36 , in cross-section, are of trough-like configuration, so that, all in all, a lenticular cross section between closure element  15  and guide part  34  is formed. 
     Spacers serve to ensure that the single magnets  24 ,  25  are always spaced apart, to be precise even in the opening position of the closure element  15 . The single magnets  24 ,  25  with lesser diameter than the respective support, namely than the closure piece  21  on the one hand and the closure element  15  on the other hand. The spacers are arranged in a region outside the free faces of the single magnets  24 ,  25 . In the present illustrative embodiment, one of the parts, in this case the movable closure element  15 , has a distancing ring  26  fitted thereto, which has transversely or radially directed apertures  27  or recesses for the passage of the medium. The apertures  27  are delimited by projections, which are formed by the spacers arranged distributed all the way round. The apertures  27  are located in the region of the flow channels  36  of the closure element  15 . 
     One particularity is the configuration of the valve seat  14 . The valve seat  14  consists of an insert  28  of high-strength material, in particular of ceramic. In the insert at least one nozzle opening, in the present case a central nozzle opening  13 , is provided. On the side facing the closing piece  16 , a funnel-shaped depression in the insert  28  leads to the nozzle opening  29 . 
     The insert  28  is connected to a holder, namely a holding ring  30 , in particular of metal, namely of special steel. The insert  28  is fixed in the holding ring  30 , in particular connected to the latter by gluing. The holding ring  30  is, for its part, detachably fitted to the valve housing  11 , in the present example by means of a thread  31 . On the free side of the holding ring  30 , recesses, namely blind holes  32 , are made, which to enable a tool to be applied for the introduction or release of the holding ring  30  in the counterthreaded valve housing  11 . 
     A further particularity of the valve of any chosen embodiment is the cooling of the valve housing  11 . According to  FIG. 6 ,  FIG. 7 , an automatically working cooling is installed, to be precise by the fitting of cooling pipes, so-called heat pipes  38 , on the valve housing  11  or in the valve housing  11 . The heat pipes  38  are embedded in the valve housing  11  outside the region of the electromagnet  23  or outside the winding of the same. In a valve housing  11  of square cross section ( FIG. 7 ), four heat pipes  38  are arranged at the corners of the valve housing  11 . The heat pipes  38  extend at least over the full height of the windings of the electromagnet  23 . An upper pipe section  39  projects from the valve housing  11 . In this part, each heat pipe  38  is provided with transversely directed fins  40  for dispersing the heat to the environment. The heat pipes  38  automatically cause the heat to be dispersed by flow to the free, open, upper end. 
     The closure piece  21  is specially positioned (adjustably) in the valve housing  11 . The closure piece  21  is disposed as a cylindrical piece in fitting arrangement in the cylindrical part of the valve chamber  19 . Attached to the closure piece  21  is an adjusting element for adjusting the position of the closure piece  21 , here in the form of an adjusting screw  41 . This is connected to a free end part of the closure piece  21 , and enters namely with a free end into an axial recess  42 . In said axial recess, the end of the adjusting screw  41  is anchored, in particular by a (metal) adhesive. The fixed support is held adjustably in the valve housing  11  by the adjusting screw  41  that protrudes from the valve housing  11 , and wherein the adjusting screw  41  is connected to the fixed support by entry and press fitting and/or gluing of a free end of the adjusting screw  41  into an axial recess  42  of the fixed support. On the threaded adjusting screw  41 , an adjusting nut  43  is arranged, which sits with an internal thread on the adjusting screw  41  and is anchored with an external thread in a head  44  of the valve housing  11 . The head  44  is fixedly connected to the valve housing  11 , likewise by means of a thread. Through turning of the adjusting screw  41 , this is altered in height, with corresponding displacement of the closure piece  21 . 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 Reference symbol list 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 11 
                 valve housing 
               
               
                 12 
                 glue line 
               
               
                 13 
                 valve opening 
               
               
                 14 
                 valve seat 
               
               
                 15 
                 closure element 
               
               
                 16 
                 closing piece 
               
               
                 17 
                 intermediate piece 
               
               
                 18 
                 plunger piece 
               
               
                 19 
                 valve chamber 
               
               
                 20 
                 inner space 
               
               
                 21 
                 closure piece 
               
               
                 22 
                 seal 
               
               
                 23 
                 electromagnet 
               
               
                 24 
                 single magnet 
               
               
                 25 
                 single magnet 
               
               
                 26 
                 distancing piece 
               
               
                 27 
                 aperture 
               
               
                 28 
                 insert 
               
               
                 30 
                 holding ring 
               
               
                 31 
                 thread 
               
               
                 32 
                 blind hole 
               
               
                 34 
                 guide part 
               
               
                 35 
                 inner face 
               
               
                 36 
                 flow channel 
               
               
                 37 
                 projection 
               
               
                 38 
                 heat pipe 
               
               
                 39 
                 pipe section 
               
               
                 40 
                 fins 
               
               
                 41 
                 adjusting screw 
               
               
                 42 
                 recess 
               
               
                 43 
                 adjusting nut 
               
               
                 44 
                 head