Abstract:
Disclosed is an applicator ( 1 ) for applying fluid to a substrate, comprising valve mechanisms ( 21 ) which are arranged in a row and are each equipped with an application valve nozzle ( 31 ), and a distributing fluid chamber ( 11 ) that has a fluid intake duct ( 110 ). A cleaning valve mechanism ( 21 ) which is incorporated into the row of application valve mechanisms ( 21 ) and is fitted with a cleaning valve nozzle ( 30 ) is associated with the fluid intake duct ( 110 ). A flow path ( 100 ) for cleaning the fluid chamber ( 11 ) is formed between the fluid intake duct ( 110 ) and the cleaning valve mechanism ( 20 ) in the distributing fluid chamber ( 11 ), said flow path ( 100 ) being effective when the cleaning valve nozzle ( 30 ) is open. Also disclosed is a method for cleaning said applicator ( 1 ). In said method, pressurized cleaning fluid is applied to the distributing fluid chamber ( 11 ), the application valve mechanisms ( 21 ) are kept closed while the cleaning valve nozzle ( 30 ) is opened, and the cleaning valve nozzle ( 30 ) is then closed while the application valve mechanisms are opened when the pressurized cleaning fluid is applied to the distributing fluid chamber ( 11 ). A valve mechanism ( 2 ) of the applicator ( 1 ) encompasses a detachably mounted nozzle diaphragm ( 3, 4 ) which unblocks a valve piston ( 51 ) in the removed state. The valve mechanism ( 2 ) further encompasses a straight fluid duct that remains free of flow corners. A setting piston ( 61 ) is movably mounted for adjusting and setting the stroke of the valve piston ( 51 ).

Description:
[0001]    This application is a 35 U.S.C. §371 filing of International Patent Application No. PCT/EP2008/004122 filed May 20, 2008, which designates the United States and claims the benefit of European Application No. 07090124.4 filed Jun. 14, 2007. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The invention concerns an application device for applying fluid to a substrate, comprising valve devices which are arranged in a row and are each equipped with an application valve nozzle for emitting the fluid under pressure and with associated valve actuating device for controlling the emission of fluid by closing and opening the application valve nozzles, and comprising a common distributing fluid chamber which can be subjected to pressure from the fluid and which connects the application valve devices to each other for admission of the fluid, the distributing fluid chamber being provided with a fluid intake duct which is arranged in such a way that the fluid which is under pressure in the distributing fluid chamber is distributed along the row of application valve devices to the latter. The invention also relates to a method for cleaning the application device as well as a valve device for the application device. 
         [0003]    An application device which is in particular equipped with electromagnetically operated valves is concerned. The valves are opened and closed by individual activation in order to produce an application in dots or dashes, which can result in a two-dimensional application, on a substrate, e.g. a flat strip of material or a surface portion. Any liquid substance is suitable as the application fluid, in particular dye or ink for a colour application. Also, coating or impregnation with adhesives, coating agents or the like can be carried out. Activation determines applied quantities, areas of application, patterns and/or applied symbols. 
         [0004]    Cleaning and maintenance of the application device are particularly important. The valve nozzles have a diameter of e.g. only 60 to 150 micrometres. The valve nozzles and fluid paths in the valve devices can easily be blocked by very fine particles or minute deposits. Ordinary application devices frequently have to be completely dismantled in order in particular to clean the distributing fluid chamber which supplies the valve devices jointly. Contamination occurs in particular after an initial assembly. But breakdowns due to deposits also occur while operation is ongoing. Also, there are special cleaning requirements if the application substance is to be exchanged, that is, for example, a change of colour is to be made. Conventional application devices then usually have to be completely or largely dismantled into their constituent parts and, after subsequent assembly, adjusted with considerable effort using separate micrometric measuring devices. Here, the invention is to provide a remedy. 
       SUMMARY OF THE INVENTION 
       [0005]    The invention is based on the aims of improving and simplifying the cleaning of the application device and its valve devices. The application device and the valve device are to be capable of being effectively and easily cleaned in a large number of cases even without dismantling, in particular also while retaining adjustment settings of the valve nozzles. 
         [0006]    The aims of the invention are achieved in conjunction with the features of the application device of the kind mentioned hereinbefore, by the fact that at least one cleaning valve device which is incorporated into the row of application valve devices for connection to the distributing fluid chamber and is fitted with a cleaning valve nozzle and with associated valve actuating device for closing and opening the cleaning valve nozzle, is associated with at least the one fluid intake duct of the distributing fluid chamber, a flow path which is effective when the cleaning valve nozzle is open, for cleaning the common distributing fluid chamber, being formed in the distributing fluid chamber between the fluid intake duct and the at least one associated cleaning valve device. 
         [0007]    The aims are achieved in a method according to the invention for cleaning the application device according to the invention, by the fact that (i) the distributing fluid chamber which connects the valve devices in a row along the associated cleaning flow path to each other, admits pressurised cleaning fluid, (ii) the application valve devices are kept closed while on the other hand the cleaning valve nozzle of the cleaning valve device associated with the cleaning flow path is opened, and (iii) then the cleaning valve nozzle of the cleaning valve device is closed and the application valve devices are opened when the distributing fluid chamber admits pressurised cleaning fluid. 
         [0008]    Advantageously, a valve device of an application device according to the invention for applying fluid to a substrate, in particular in a plurality for arrangement in a row in the application device, comprises a valve housing having a valve seat with valve nozzle for emitting the fluid under pressure, a supply fluid chamber which can be subjected to fluid pressure, a valve actuating device which is formed by an electromagnetic device with valve piston movable back and forth against a return force and engaging in the valve seat for closing and opening the valve nozzle, and a piston stop against which the valve piston operates, the valve actuating device being arranged between the supply fluid chamber and the valve housing, and the valve housing together with the valve nozzle being detachably mounted on the nozzle side of the valve device which has the valve nozzle, as a result of which the valve piston is freed when the valve housing is removed, the valve device being provided with at least one rectilinear fluid duct that remains free from flow corners and that, passing the valve actuating device, connects the supply fluid chamber to the valve seat, the valve piston and part of the piston stop together forming a wall of the straight fluid duct which is freed when the valve housing is removed, and the piston stop being formed by an adjusting piston which is mounted so as to be displaceable in the direction of the stroke for setting and adjusting the piston stroke. 
         [0009]    The application device according to the invention is in particular distinguished by the fact that the distributing fluid chamber which supplies all the valve devices of the application device with fluid can be cleaned easily and effectively without the application device being opened or dismantled. The cleaning valve device is designed according to the invention in such a way that, when the cleaning nozzle is open and the application nozzles are closed, the common fluid chamber is flushed by the fact that cleaning fluid under pressure is forced at high speed and hence entraining contaminants through the distributing fluid chamber. In order to form the cleaning flow path through the distributing fluid chamber, the valve nozzle of the cleaning valve device has a relatively large nozzle cross-section. This is a nozzle cross-section which is not suitable for fluid application. As a result, the cleaning valve device differs crucially from the application valve devices. In other respects, the cleaning valve device and the application valve devices of the application device are appropriately designed the same and matching in order to manufacture the application device cheaply and simplify valve control. 
         [0010]    With the application device according to the invention, a particularly effective cleaning method can be carried out. Thus it is particularly advantageous if the application valve devices are cleaned by the fact that method steps i) to iii) are carried out under the control of a program using electronic control means, the valve nozzles being closed and opened under the control of the valve actuating devices, and in method step iii) the application valve devices being opened by opening the application valve nozzles. Preferably, the application valve devices are in each case only opened individually one after the other, while the other application valve nozzles are kept closed. Appropriately water is used as the fluid for cleaning, if need be with a cleaning agent which dissolves application substance or some other suitable cleaning fluid. 
         [0011]    Control of the cleaning method with controlled closing and opening of the nozzle openings can take place in a simple manner with an electronic processor control device designed for this purpose, by the fact that the latter is provided with a control program which presents the above sequence of method steps and prepares them for execution. Such a control device can be designed in the usual manner e.g. with a computer in conjunction with a program representing the steps of the method. 
         [0012]    Although it may be provided according to the invention that several groups of valve devices which are each arranged between a cleaning valve device and a fluid intake duct, in association therewith, are formed in one application device, a preferred embodiment of the invention consists in that the fluid intake duct and the associated cleaning valve device are provided singly, all the application valve devices of the application device being arranged between the one fluid intake duct and the one cleaning valve device. It was found that, in particular with such an arrangement, a particularly effective cleaning flow path through the distributing fluid chamber is produced if the cleaning valve nozzle of the cleaning valve device has an effective flow cross-section which is many times larger, preferably approximately 10 times larger, than the corresponding or largest flow cross-section of the application valve nozzles of the application valve devices. 
         [0013]    An application device according to the invention which is particularly preferred in practice, in particular for colour application, comprises the one cleaning valve device and eight application valve devices. But also devices with fewer application nozzles, for example with five nozzles, or with more application nozzles, e.g. with fifteen nozzles, prove to be particularly practical. Application units with preferably five to fifteen application valve devices and the one cleaning valve device are appropriately also designed as a module element which is assembled with identical module elements into an application device with nozzles arranged in rows and columns. Such application module elements can be assembled with socket connections and/or screw connections. 
         [0014]    An application device according to the invention is in a preferred embodiment designed with electromagnetically operated valve devices. In conjunction with the arrangement of the cleaning valve device according to the invention, particular advantages can be obtained. 
         [0015]    The electromagnetic embodiment of the application device according to the invention consists in that the valve actuating devices of the valve devices are arranged in a row spatially between the distributing fluid chamber and the nozzle side of the application device that comprises the valve nozzles of the valve devices, in that each valve actuating device comprises an electromagnet device with a valve piston movable back and forth against a return force, in that each valve device has a valve housing with valve nozzle and valve seat with which the associated valve piston for closing and opening the valve nozzle cooperates, in that each valve device is designed with a piston stop against which the valve piston operates, the piston stop being formed by an adjusting piston which is mounted so as to be displaceable in the direction of the stroke for setting and adjusting the piston stroke, and in that each valve device is provided with at least one rectilinear fluid duct which remains free from flow corners and which connects the common fluid chamber to the valve seat, the valve piston and part of the adjusting piston together forming a wall of the straight fluid duct, and each valve device on the nozzle side of the application device having a mounting opening in which the valve housing as the closure element is inserted in a releasable connection and which, when the valve housing is removed, frees the valve piston for removal from the valve device and the straight fluid duct comprising the piston wall. 
         [0016]    The above application device according to the invention equipped with electromagnetic valves, in conjunction with the cleaning valve device provided according to the invention and the cleaning flow path obtained as a result, also offers advantages for cleaning the valve fluid ducts between the distributing fluid chamber and the application valve nozzles. Thus according to the invention it is important that first of all cleaning of the distributing fluid chamber is carried out by fluid flow at high speed, and therefore from the supply fluid duct to the cleaning valve nozzle a considerable stream of cleaning fluid which entrains contaminants is produced. As it is ensured that the common distributing fluid chamber is first cleaned, the individual application valve devices can now also be flushed at high pressure, appropriately individually in succession, as described above. No dirt can pass from the distributing fluid chamber that has already been flushed into the valve fluid duct which is being flushed between the distributing fluid chamber and the associated application valve nozzle. The rectilinear valve fluid duct which remains free from flow corners in this case ensures excellent flushing. Flow shadows which arise in known application devices due to undercuts, dead corners, areas with slow flow speeds or the like, are avoided. Harmful air bubbles are avoided, because particularly effective deaeration is achieved by the straight flow path running on the wall of the adjusting piston and the valve piston. With the application valve device in each case opened individually, the cleaning fluid cleans the path between the distributing fluid chamber and the valve seat or the valve nozzle arranged thereon, without the application device having to be dismantled. An important advantage here also lies in that the adjusting position of the valve piston set with the adjusting piston is maintained. 
         [0017]    Appropriately, the valve nozzle forms part of the valve housing. A nozzle orifice is formed. Only by exchanging the valve housing for a valve nozzle with different dimensions, can different degrees of fineness and fluid quantities (ink quantities) be obtained for application. 
         [0018]    A further advantage of the above embodiment lies in that, after the distributing fluid chamber has been cleaned according to the invention, the fluid duct between the distributing fluid chamber and the associated application nozzle can also be cleaned by the fact that the detachably mounted valve housing is removed in case of major contamination. The valve housing and the valve piston are easily removed and remounted on the nozzle side of the application device, that is, on the lower side of the device which forms the application side. Such partial dismounting may be necessary if a change of fluid is to be made, e.g. a change of colour. Unlike conventional application devices, the adjusting pistons, i.e. adjusting devices arranged for this purpose on the upper or rear side of the application device, are not dismounted. This is a considerable advantage, as it is the adjusting devices that are very sensitive to damage. The slightest damage can already falsify adjustments within a range of a few micrometres. Flushing of the distributing fluid chamber with the cleaning valve device according to the invention also covers the adjusting pistons for cleaning, without dismounting taking place on the upper/rear side of the application device. 
         [0019]    The valve device of an application device according to the invention even in the single form achieves the result that, along the straight valve duct path between the supply fluid chamber and the valve nozzle, a straight longitudinal flow takes place. The longitudinal construction avoids flow shadows which would otherwise arise due to undercuts, dead corners, areas with slow flow speeds or the like. Hence not only can the valve device, as already described, be cleaned particularly well by flushing through. Due to the longitudinal flow, the inner region of the electromagnet device, namely a magnet coil which partly surrounds the adjusting piston and the valve piston, is effectively cooled as well. This has a favourable effect on the life of the valve device. Design and assembly of the valve device are particularly simple. 
         [0020]    Furthermore, the single valve device also has the advantages which were mentioned in connection with the valve devices of the application device. In case of particularly major blockage, the valve housing can easily be removed. The mounting opening is so large that the valve piston likewise can easily be taken out. Hence the valve fluid duct or the piston chamber opens towards the nozzle side, that is, downwards. By flushing with cleaning fluid under pressure, the valve fluid duct and the piston chamber are flushed through, and any particles of dirt present are flushed out downwards. The adjusting piston and the adjusting device are not dismounted. Adjustment settings can be made precisely even during operation of the device, that is, during application. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    Subsidiary claims are aimed at the above and other appropriate and advantageous embodiments of the invention. Particularly appropriate and advantageous embodiments or possible designs of the invention are described in more detail with the aid of the following description of the practical examples shown in the schematic drawings. They show: 
           [0022]      FIGS. 1A to 1D  in side views or axonometric view, an application device according to the invention with eight application valve nozzles and one cleaning valve nozzle, 
           [0023]      FIG. 2  a longitudinal section through an application device according to  FIGS. 1A  to D, 
           [0024]      FIG. 3  detail D of  FIG. 2 , and 
           [0025]      FIG. 4  a single valve device according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0026]    The application device according to the invention shown in  FIGS. 1A  to D comprises a box-like valve body  15  which is composed of a lower socket portion  151  and an upper cover portion  152 . The lower portion  151  is closed by a narrow elongate nozzle plate  121  which receives valve nozzles  3 . The valve nozzles  3  are arranged in a straight row on the nozzle/application side  12 . On the opposite side, the application device  1  has an electrical plug-in connection  17  and a connecting opening  16  for application fluid. In the practical example the row of valve nozzles  3  is defined by eight application valve nozzles  31  and one cleaning valve nozzle  30  which closes the row of nozzles. The cleaning valve nozzle  30  is according to the invention arranged at the end of the row of nozzles opposite the connecting opening  16 . 
         [0027]    As can be seen from the sectional view in  FIG. 2 , the valve body  15  is connected to an electronic power switching device  9 . This switching device  9  is connected by means of a frame  19  in a plug-in connection  18  to a cap  153  of the upper portion  152 . In this connection the switching device  9  is electrically connected to the valve body  15  directly via the plug-in connection  17 , without using a flat-strip cable connection. The electrical plug-in connection  17  makes electrical connections, not shown, to electromagnetic valve actuating devices  5  of the application device  1 . 
         [0028]      FIG. 2  and the detail according to  FIG. 3  show the design and structure of the application device  1  according to the invention in an embodiment. 
         [0029]    In the lower portion  151  are formed recesses which receive nine valve devices  2  in a straight row next to each other. The valve device  20  at one end of the row is a cleaning valve device provided according to the invention, which is equipped with the cleaning valve nozzle  30 . The other eight valve devices  21  are application valve devices of which the valve nozzles  31  emit application fluid which is under pressure during regular operation. 
         [0030]    In the upper portion  152  of the valve body  15  is formed a distributing fluid chamber  11  which can be supplied with pressurised fluid from one side by the connecting opening  16  via a fluid intake duct  110 . The chamber is in the shape of an elongate duct having a substantially circular cross-section, which extends along the row of valve devices  2 . The distributing fluid chamber  11  is provided with openings  73  at equal intervals on its side facing towards the valve actuating devices  5 . This involves in each case the opening  73  of a through-bore  70  or through-hole in the lower portion  151 . The through-bore  70  opens out in a projection  154  which engages in a mounting opening  13  of the nozzle plate  121 . 
         [0031]    The lower portion  151 , the nozzle plate  121  which closes the latter at the bottom, the upper portion  152  and the cap  153  which closes the latter at the top are appropriately joined together with screw connections not shown in more detail. The advantage obtained with the invention is that these parts remain in the mounted state when the application device  1  is cleaned. 
         [0032]    In  FIGS. 1A  to D can be seen a closure element  155  with which the fluid distributing duct  111  is closed sealingly at its end opposite the fluid intake duct  110 . This closure element may if required be used to deaerate the distributing fluid chamber  11 . Due to the measures according to the invention, however, it is not necessary to remove this closure element  155  for cleaning the application device  1 . Even deaeration takes place only by way of exception. 
         [0033]    The valve devices  2 , namely the cleaning valve device  20  and the application valve devices  21 , are basically designed the same and matching. According to the invention, however, an essential difference lies in that the cleaning valve device  20  at the end of the row is equipped with the cleaning valve nozzle  30  which has a substantially larger flow cross-section than the flow cross-section of the application valve nozzle  31  of each application valve device  21 . In the embodiment, the application valve nozzles  31  have the same flow cross-section. In the embodiment, the flow cross-section of the cleaning valve nozzle  30  is to be ten times larger than the flow cross-section of the application valve nozzle  31 . 
         [0034]    The valve device  2  which is therefore provided nine times is described below. 
         [0035]    The electromagnetic valve device  2  comprises the valve actuating device  5  arranged in the valve body  15 , a valve housing  4  with the valve nozzle  3  and a valve seat  41 , a valve piston  51 , and an adjusting device  6  with an adjusting piston  61  against which the valve piston  51  operates. The valve housing  4  with the valve nozzle  3  forms a screw-in nozzle orifice. 
         [0036]    The valve actuating device  5  is designed as an electromagnet device with a magnet coil  50  which surrounds the through-bore  70 . From the through-bore  70 , on the projection  154  the valve piston  51  protrudes downwards into a piston chamber  8 . The valve piston  51  forms the electromagnet armature of the magnet coil  50  and enters the magnet coil  50  in the through-bore  70 . The valve piston  51  is mounted centrally in the through-bore  70 . Appropriately multipoint mounting, not shown, is provided. This can be formed by three knobs offset by 120° each on the longitudinal circumference of the valve piston  51 . Thus between the longitudinal circumferential surface of the valve piston  51  and the bore wall of the through-bore  70  is formed an annular gap. The through-bore  70  and the valve piston  51  appropriately have a circular cross-section. 
         [0037]    The rear side of the valve piston  51  which lies in the magnet coil  50  abuts against a congruent piston stop  60  of the adjusting piston  61 . The adjusting piston  61  enters the magnet coil  50  in the through-bore  70  from the side of the distributing fluid chamber  11 . In the process, the adjusting piston  61  extends approximately two-thirds in the magnet coil, while the valve piston  51  enters the remaining one-third. The through-bore  70  and through-hole form a common piston chamber in which the two pistons are held. The adjusting device  6  comprises a screw connection  63  which is formed on the wall of the distributing fluid chamber  11  that lies opposite the wall with the fluid intake openings  73 . 
         [0038]    The adjusting piston  61  has the same cross-section as the valve piston  51 , the two pistons being aligned. The adjusting piston  61  is centred in the through-bore  70  by the screw mounting of the screw connection  63 . Thus likewise an annular gap is formed between the longitudinal circumference of the adjusting piston  61  and the wall of the through-bore  70 . The two annular gaps in the through-bore  70  along the adjusting piston  61  and along the valve piston  51  form a valve fluid duct  7  in the form of a ring-chamber duct  72 . The latter extends from the fluid intake opening  73  to the outlet opening  74  at the projection  154 . The ring-chamber duct  72  forms, along the two pistons  51 ,  61  and the through-bore  70 , a rectilinear flow path which remains free from corners and edges forming flow shadows. In this respect, it is also important according to the invention that the adjusting piston  61  and the valve piston  51  come into contact with closed surfaces. Between the contact faces in the practical example there is only a stroke distance of approximately 0.5 μm. In every case the stroke distance with the closed end faces of the two pistons  51 ,  61  is kept so small that the flow through the ring-chamber duct  72  remains smooth and undisturbed in a straight path. 
         [0039]    The adjusting piston  61  extends far into the distributing fluid chamber  11  at the fluid intake opening  73  of the ring-chamber duct  72 . The cross-section of the adjusting piston  61  is kept relatively small in the flow cross-section of the distributing fluid chamber  11 , in order to obtain a large effective flow cross-section towards the fluid intake openings  73  in the distributing fluid chamber  11 . 
         [0040]    The valve housing  4  is designed in the form of a nozzle orifice which is a closure member  14  easy to attach and remove. The valve housing  4  is formed as a swivel part with an external thread and screwed in a releasable screw connection into the associated internally threaded mounting opening  13  in the nozzle plate  121 . The valve housing  4  ends on the outside with an edge orifice abutting against the nozzle/application side  12 . The valve nozzle  3  is embedded centrally in the valve housing  4 . It is advantageously made of ceramic and can be inserted firmly in the valve housing  4  by pressing it in. 
         [0041]    The valve housing  4  has a frustoconical inner chamber  8  which corresponds to the projection  154 , in order to receive the latter precisely and centrally. Furthermore, the inner chamber  8  of the valve housing  4  is designed to receive a pretensioned conical spring  52  which forms part of the valve actuating device  5 , pressing a head closure element  54  of the valve piston  51  for closing the valve nozzle  3  against the latter. The valve nozzle  3  on the side of the valve piston  51  is recessed with the valve seat  41  which is engaged by the valve piston  51  with the head closure element  54 . In the process, the conical spring  52  which is seated on the valve piston  51  is held or clamped in its pretensioned state between an annular edge of the projection  154  and an annular edge at the head end of the valve piston  51 . 
         [0042]    As will not be described in more detail here and can be seen from the drawings, the components of the application device  1  are sealed off from each other at contacting form-locking surfaces in the region of fluid-conducting chambers and ducts in the usual manner with seals, e.g. O-rings. 
         [0043]    In particular with reference to  FIGS. 2 and 3 , operation of the cleaning valve device  20  and the performance of steps of the method according to the invention are illustrated. 
         [0044]    Via the fluid intake duct  110 , the distributing fluid chamber  11  admits pressurised cleaning fluid. This takes place in a state in which all the valve devices  2  are closed. In  FIGS. 2 and 3 , to clarify the drawings only the cleaning valve nozzle  30  is inserted in the nozzle plate  121 . Naturally, to close all the valve devices  2  the other valve housings  4  are likewise mounted on the nozzle plate  121 . Appropriately water, if necessary mixed with a cleaning agent which particularly dissolves application substance, is used as the cleaning fluid. 
         [0045]    While the application valve devices  21  are now kept closed, the cleaning valve nozzle  30  is opened with the associated valve actuating device  5 . The valve piston  51  is moved against the force of the conical spring  52  over the stroke distance towards the adjusting piston  61 , so that cleaning fluid flows out of the cleaning valve nozzle  30  under pressure. The cleaning valve nozzle  30  has, as described above, a relatively large flow cross-section. As a result, the fluid passes from the fluid intake duct  110  at a high flow rate along the path  100  in the distributing fluid chamber  11  through the ring-chamber duct  72  of the cleaning valve device  20  to the cleaning valve nozzle  30 . Along the flow path  100 , which passes all the valve devices  2 , contaminants such as particles or deposits are removed particularly effectively from the distributing fluid chamber  11 . This involves tiny particles for which the rectilinear ring-chamber duct  72  is not an obstacle. It is important in this respect that, on account of the large nozzle opening, a high flow that entrains very fine contaminants is produced. Here it is emphasised that the flow cross-section of the cleaning valve nozzle  30  is so large that this nozzle is not suitable for application and is not used for this. The stroke of the adjusting device  6  of the cleaning valve device is set so long that the flow cross-section of the valve nozzle  30  comes into its own. 
         [0046]    After the distributing valve chamber  11  has been flushed in the manner described, the cleaning valve device  20  is closed by switching off the valve actuating device  5 . The application valve devices  21  are now successively opened by activation of the associated valve actuating devices  5 . That is to say, in succession there is always only one of the application valve nozzles  31  open, while the other application valve nozzles  31  are kept closed. The distributing fluid chamber  11  is supplied with pressurised cleaning fluid. In this way, in each case effective cleaning and flushing of the ring-chamber duct  72  as well as of the inner chamber  8  of the valve housing  4  which receives the conical spring  52  and includes the application valve nozzle  30  is achieved. 
         [0047]    The sequence of applications of cleaning fluid under pressure as well as opening and closing the valve devices  2  that is carried out for the cleaning method described is advantageously performed by an electronic control device. The latter is designed with a control program such that the sequence of steps is predetermined and can be carried out in the manner according to the invention. The usual electronic control means of a computer and/or a logic circuit for application control can be used as the electronic control device, the program steps according to the invention being integrated in addition. An electronic control device of this kind is not shown in the drawings. It is wired to the electrical contacts  91  of the electronic power device  9  for a example using a logic circuit board. 
         [0048]    According to the cleaning method described above in the practical example, the application device  1  is particularly effectively flushed in particular after the initial assembly. It is a great advantage that cleaning and flushing take place in a state of the application device in which the adjusting devices  6  of the application device  1  remain mounted. On the side of the application device  1  opposite the nozzle plate  121 , there is therefore no handling by dismounting. 
         [0049]    Only in special cases, namely if major contamination in the valve devices is to be remedied, is the above flushing of the distributing fluid chamber  11  by opening the cleaning valve nozzle  30  of the cleaning valve device  20  carried out according to the invention first of all while the application valve devices  21  are closed, and then the valve housings  4  of the application valve devices  21  are unscrewed and reattached successively, so that at all times only one application valve device  21  is being cleaned. 
         [0050]    Removal of the valve housing  4  is particularly simple. After the valve housing  4  has been removed, the mounting opening  13  exposes the valve piston  51  and the conical spring  52 , parts which, as such, can easily be removed downwards through the mounting opening  13 . Then flushing takes place under high pressure, for example with water or a special cleaning agent. The valve piston  51 , the conical spring  52  and the valve housing  4  with its valve nozzle  3  are cleaned individually. Furthermore, to complete cleaning, the valve housing  4  of the cleaning valve device  20  can also be removed and, while the application valve devices are then closed, flushed with water. Such measures take place only in case of exceptions where there is major contamination. In most cases the application valve devices  21  can be cleaned particularly effectively according to the invention without removing the valve housings  4  (nozzle orifices). 
         [0051]    With the cleaning methods last described too, it is of particular importance that the adjusting devices  6  remain mounted. Handling is necessary only on the lower side of the application device  1 . 
         [0052]    After each of the application valve devices  21  have been mounted again with valve piston  51 , conical spring  52  and valve housing  4 , in each case the desired fine stroke between closed position and open position of the valve piston  51  is adjusted in a simple manner with the adjusting device  6 . For this purpose the adjusting device  6  has a micrometric fine thread  622  with adjusting screw  621 . 
         [0053]    An application device  1  as described in the embodiment of  FIGS. 1 to 3  can also appropriately be provided as a module unit which can be assembled with identical module units into an application device with nozzles arranged in rows and columns. 
         [0054]    In the embodiment described, the valve devices  2  are accommodated and formed in parts  151  to  153  of the common valve body  15 . Naturally, the valve devices can also each be formed by a single valve device. Such a valve device is shown in the embodiment in  FIG. 4 . 
         [0055]    The single valve device has the same parts or corresponding parts as the valve device  2  of the application device  1  described. In  FIG. 4  this is indicated by the fact that the reference numbers used in  FIGS. 1 to 3  are used with the number 1 after the dot. A single valve device  2 . 1  according to  FIG. 4  can be assembled in a plurality into an application device according to the invention. It is then necessary, as not shown in  FIG. 4 , to connect supply fluid chambers  11 . 1  in series by suitable sealing means, not shown. Joining single valve devices together in this way is known in the art. A valve device  2 . 1  as in  FIG. 4  has the features, functions and advantages described for the valve device  2  of the application device  1  described above in the embodiment. 
         [0056]    In particular the straight flow path of the ring-chamber duct  72 . 1  can be cleaned easily and effectively with the nozzle orifice which is easy to remove and fit. The nozzle orifice can be exchanged and mounted quickly with the desired valve nozzle  3 . 1 . Only handling on the lower side of the valve device  2 . 1  takes place. On the upper/rear side of the valve device  2 . 1 , all parts remain mounted. The adjustment setting can be carried out easily and precisely in spite of the exchangeable nozzle orifice. The straight flow path of the ring-chamber duct  72 . 1  has the advantage of avoiding flow shadows in which particles are otherwise caught, in the region of which deposits arise and/or which impair the through-flow for example as a result of trapped air. Due to the longitudinal flow, the inner region of the magnet coil  50 . 1  is cooled very effectively.