Abstract:
A modular spray gun manifold having a plurality of spray gun modules arranged in a lateral array each separated by an adjacent support assembly. Each spray gun module has a central liquid passage communicating with a spray nozzle and a transversely oriented liquid inlet port communicating through an outer side of the spray gun module for connection with an independently controllable liquid supply. The spray gun modules further include a recirculation port communicating between the central passageway and a recirculation conduit in an adjacent support assembly. A control valve of each module is operable when in open spraying position for blocking communication of liquid from the central passageway to the circulation port and when in a valve closing position blocking the liquid flow to the spray nozzle while redirecting liquid from the liquid inlet to the recirculation port for recirculation through the manifold array.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application claims the benefit of U.S. Patent Application No. 61/815,125, filed Apr. 23, 2013, which is incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to spray gun type liquid spray devices, and more particularly, to a spray gun manifold having a modular construction. 
     BACKGROUND OF THE INVENTION 
     Modular spray gun manifold assemblies that include a plurality of laterally spaced spray guns supported in a row for discharging an elongated spray pattern are known. Such manifolds are used, for example, in pill coating machines in the pharmaceutical industry. Spray gun manifolds, such as shown in U.S. Pat. No. 7,083,121 B2 assigned to the same assignee as the present application, the disclosure of which is incorporated herein by reference, comprise spray gun modules disposed between respective support assemblies through which pressurized air and liquid are directed for supplying the plurality of spray gun modules. Liquid directed through the manifold also is recirculated back to the liquid supply. 
     In some spray applications, it is desirable to monitor the liquid supply to each individual spray gun module in order to detect possible blockage in the spray discharge. For this purpose, it has been necessary to individually supply pressurized liquid to the spray gun modules, rather than through the manifold system, in order to more reliably detect the interruption of discharge of the individual spray gun. While it is also desirable that the liquid be continuously recirculated through the system, when pressurized liquid is individually supplied to the spray gun modules, rather than through the manifold system, this has presented problems. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a modular spray gun manifold in which the plurality of spray gun modules have individual pressurized liquid feeds and which facilitates efficient recirculation of the liquid. 
     Another object is to provide a novel spray gun module for use in such a manifold system. 
     A further object is to provide a spray gun module of the foregoing type which is relatively simple in construction and lends itself to economical manufacture and reliable usage. 
     Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective of an illustrative modular spray gun manifold in accordance with the invention mounted on a support structure; 
         FIG. 2  is a partially diagrammatic depiction of the spray gun manifold shown in  FIG. 1 ; 
         FIG. 3  is an enlarged, partially exploded, perspective of the modular spray gun manifold shown in  FIG. 2 , showing one of the spray gun modules and the adjacent support assemblies in separated relation to each other; 
         FIG. 4  is a vertical section of one of the spray gun modules of the illustrated manifold showing a flow control valve thereof in an open position and in this case depicting a liquid inlet in an upper exposed side; 
         FIG. 4A  is an enlarged fragmentary section of the discharge end of the spray gun module shown in  FIG. 4 ; 
         FIG. 5  is an end view of the discharge end of the spray gun module shown in  FIG. 4 ; 
         FIG. 6  is a vertical section of the spray gun module, similar to  FIG. 4 , showing the flow control valve end of the module in an closed position; and 
         FIG. 6A  is an enlarged fragmentary section of the discharge end of the spray gun module shown in  FIG. 6   
     
    
    
     While the invention is susceptible of various modifications and alternative constructions, a certain illustrative embodiment thereof has been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now more particularly to the drawings, there is shown an illustrative modular spray gun manifold  10  which includes a plurality of spray gun modules  11  in accordance with the invention. The spray gun modules  11  each are interposed between support assemblies  12 , and the manifold  10  in this case is mounted on a support pipe  14  by laterally spaced brackets  15 . The spray gun modules  11  have lateral sides  23  disposed in abutting relation to lateral sides  27  of adjacent support assemblies  12  and outer exposed forward, rear, upper and bottom sides  24 . 
     Each illustrated spray gun module  11  includes a generally blocked shaped body  15 , a spray nozzle assembly  16  supported on a front exposed side  24  of the module body  15 , and a valve actuator  17 , and end cap  18  supported at the opposite rear exposed side  24  of the modular body  15 , as depicted in  FIG. 2 . The illustrated spray nozzle assembly  16  includes a spray tip or nozzle insert  20  and an air cap  21  mounted in overlying surrounding relation to the spray tip  20  ( FIG. 4A ) and retained on the nozzle body  15  by a retaining nut  22 . The nozzle body  15  has a liquid inlet  25 , a cylinder air inlet  26 , an atomizing air inlet  28 , and a fan air inlet  29  ( FIG. 4 ). Liquid is supplied to the inlet  25  communicates with a central longitudinal passageway  30  in the nozzle body  15  and spray tip  20  and through a liquid discharge orifice  31  defined by a forwardly extending nose portion  32  of the spray tip  20  ( FIG. 4A ). In the illustrated embodiments, it will be understood that the liquid inlet  25  may communicate through the bottom expose side  24  ( FIGS. 1-3 ) or the upper exposed ( FIGS. 4-6 ). 
     For controlling the discharge of liquid from the spray gun module  11 , a valve needle  35  coaxially extends through the housing body  15  for reciprocating movement between a valve closing position in seated engagement with a downstream tapered entry section of the spray tip passageway  30  and an unseated valve open position. The valve needle  35  in this case has a tapered seating section and an axially extending clean out nose portion that is positionable into and through the discharge orifice  31  when in a closed position ( FIG. 6A ) for maintaining the passage free of buildup during usage. 
     For operating the valve needle  35 , a piston  36  is mounted at an upstream end of the needle  35  which is biased in a valve closing direction by a compression spring  38  interposed between the piston  36  and the upstream actuator cap  18  ( FIG. 4 ). The piston  36  carries an annular sealing ring  39  in sealing engagement with a cylindrical bore in the housing body  15 . The compression spring  38  biases the piston  36 , and hence the valve needle  35 , forwardly to a fully seated, i.e., valve closed position, depicted in  FIG. 6 . The valve needle  35  is moveable axially in the opposite direction (to the left in  FIG. 6 ) against the force of the spring  38  by pressurized air (i.e. “cylinder air”) selectively directed into the cylinder air inlet  26 , which communicates through the housing body  15  with an air chamber on the downstream side of the piston  36  in a known manner. 
     For atomizing the liquid discharging from the spray tip  20 , the spray tip nose portion  32  and a central orifice of the air cap  21  define an annular atomizing air discharge orifice  40  which communicates with angled atomizing air passages  41  and an annular air passage  42  defined between the spray tip  20  and air cap  21 , which in turn communicates through nozzle body  15  with the atomizing air inlet  28 . Pressurized air directed through the annular discharge orifice  40  communicates outwardly in surrounding relation to the liquid discharge orifice  31  for interaction with the discharging liquid flow stream. 
     For forming and directing the discharging liquid spray into a flat fan spray pattern for wider lateral application, each spray gun module  11  is operable for impinging pressurized air (i.e., “fan air”) on opposite sides of the liquid spray. Pressurized air from the fan air inlet  29  of the spray gun module  11  communicates through the nozzle body  15  with an annular chamber  44  adjacent an upstream end of the air cap  21 . The annular chamber  44  communicates pressurized air to a pair of longitudinal passages  45 , which terminate in opposed angled discharge passages  46  that direct pressurized air streams at an acute angle on opposite sides of the discharging liquid spray for spreading the liquid spray into a relatively flat narrow spray pattern. 
     For communicating atomizing air, fan air, and control air to the spray gun modules  11 , the cylinder air inlet  26 , atomizing air inlet  28 , and fan air inlet  29  each is defined by a respective fluid passage  26   a ,  28   a  and  29   a  that extend transversely through opposite sides of the module body and which communicate with fluid conduits  50  in the adjacent support assemblies  12  which supply atomizing air, cylinder and control air though the manifold  10 , as best shown in  FIG. 3 . The support assemblies  12  in this case are blocks  51  within which the fluid conduits  50  are supported. The fluid conduits  50  each preferably extend outwardly a small distance beyond the respective ends of the blocks  51  for insertion into the passages of the spray gun manifold, with a threadless union therebetween (see. e.g.,  FIG. 3 ). Threaded retaining rods  52  in this instance extend through aligned holes  53  in the spray gun modules  11  and support assemblies  12  for retaining the modules and support assemblies in assembled relation to each other. 
     In accordance with one aspect of the invention, each spray gun module has a respective individual pressurized liquid feed or supply, which lends itself to reliable monitoring of the spray discharge while permitting circulation of the supply liquid through the manifold for return to the liquid supply. To this end, the liquid inlet  25  of each spray gun module body  15  is connected to a respective liquid supply  54 . In the illustrated embodiment, each module body  15  has a liquid inlet fitting  55  protruding outwardly of an outer exposed side  24  of the spray gun module for easy connection to a supply line  57  coupled to the liquid supply. In the illustrated embodiments, the liquid inlet fitting  55  is disposed in a bottom exposed side of the spray gun module ( FIGS. 1-3 ) or in an upper exposed side  24  ( FIGS. 4-6 ). It will be understood by a person skilled in the art that the inlet fittings  55  and respective supply lines may be coupled to individual liquid supply pumps, or alternatively to a multiple feed pump operable for selectively directing pressurized liquid individually to the inlet fittings  55  and the respective spray gun modules  11 . 
     In keeping with the illustrated embodiment, when the valve needle  35  is moved to the off or closed position, as depicted in  FIG. 6 , the liquid inlet  25  is enabled to communicate with a recirculation port  60  extending transversely to the block housing  15  of the spray gun module  11  for permitting continued recirculation of the liquid through the manifold  10  via passages in the spray gun modules  11  and support assemblies  15 . To this end, the valve needle  35  carries a plunger  62  intermediate its end which is movable within an enlarged passage section  6  upstream of the central fluid passageway  30  ( FIG. 4A ). The plunger  62  includes an outer annular seal  64  for sealing slide-able contact with the enlarged passageway section  6 . 
     When the valve needle  35  is in the open position during spraying ( FIG. 4A ), the plunger  62  is disposed at a location between the liquid inlet  25  and the recirculation port  60  preventing the communication of liquid from the liquid inlet  25  to the recirculation port  60 . As an incident to movement of the valve needle  35  to the shutoff position, as shown in  FIG. 6A  under the force of the spring  38  upon discontinuation of the actuating air, the plunger  62  is moved with the valve needle  35  to a position downstream of the liquid inlet  25  for permitting the continuous communication of liquid from the liquid inlet  25  to the recirculation port  60  for recirculation through the manifold  10 . For this purpose, the recirculation port  60  extends transversely through the block housing  15  for communicating with recirculation tubes  64  in the adjacent support assemblies  12 , which thereby enable the liquid to be recirculated through the manifold and return to the liquid supply regardless of whether the valve needles in the other spray gun modules  11  are in open or closed positions. 
     Hence, it can be seen that a spray gun manifold is provided in which the spray guns modules have individual liquid feeds or supplies that enables more reliable monitoring of interruptions or changes in liquid pressure and spray discharge. Yet, the spray gun modules enable automatic recirculation of the supply liquid through the manifold system when any of the valve needles of any of the spray gun modules are in their shutoff positions.