Abstract:
A constant flow regulating valve of the type described in U.S. Pat. Nos. 6,026,850 and 6,209,578 includes a closure mechanism configured and arranged to override the modulating mode of the valve and to close the valve at fluid inlet pressures both below and above the valve&#39;s threshold level. The closure mechanism may be selectively deactivated to thereby allow the valve to assume its normal pressure responsive regulating functions. Embodiments of the regulating valve incorporate pressure relief devices and vent seals, with configurations suitable for incorporation into the trigger assemblies of portable sprayers.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. Ser. No. 11/769,315 filed Jun. 27, 2007 now abandoned, which claims priority from provisional Patent Application Ser. Nos. 60/830,265 and 60,839,618 filed respectively on Jul. 12, 2006 and Aug. 23, 2006, and from Ser. No. 11/841,194 filed Aug. 20, 2007 now abandoned. This application claims priority from provisional application Ser. No. 60/888,621 filed Feb. 7, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to fluid valves, and is concerned in particular with a regulating valve that operates in response to a variable fluid inlet pressure above a selected threshold level to deliver the fluid at a constant outlet pressure and flow rate. A closure mechanism is selectively operable either to accommodate the valve&#39;s normal pressure responsive regulating functions, or to override such functions by maintaining the valve in a closed state at inlet pressures both above and below the threshold level. 
     2. Description of the Prior Art 
     Examples of known regulating valves are described in U.S. Pat. Nos. 6,026,850 and 6,209,578. Such valves are normally closed in response to fluid inlet pressures below a threshold level, and operate in a modulating mode in response to variable fluid inlet pressures above the threshold level to deliver fluids at constant outlet pressures and flow rates. However, at fluid inlet pressures above the threshold level, such valves remain open and cannot serve as shut off valves, thus making it necessary to employ additional and separately operable valves to achieve this added function. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, the known regulating valves are modified to include closure mechanisms configured and arranged to override the modulating mode of the valves and to maintain closure of the valves at fluid inlet pressures both below and above the threshold level. The closure mechanisms may be selectively deactivated to thereby allow the valves to assume their normal pressure responsive regulating functions. 
     In accordance with still another aspect of the present invention, the vent opening communicating with the valve&#39;s spring chamber is provided with a seal which allows air to escape and enter the spring chamber, but which prevents the escape of liquid from the spring chamber in the event that the valve diaphragm is breached. 
     In accordance with another aspect of the present invention, a pressure relief mechanism is provided for relieving residual fluid inlet pressure below the threshold level when the valve is closed. 
     In accordance with another aspect of the present invention, multiple valve components are preassembled into integral subassemblies that are configured and arranged for final assembly into an outer housing structure. 
     In accordance with a further aspect of the present invention, the valve is integrated into the trigger assembly of a portable sprayer. 
     These and other features, aspects and attendant advantages of the present invention will now be described in further detail with reference to the accompanying drawings, wherein: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view through a regulating valve in accordance with one embodiment of the present invention, the valve being shown in its open condition; 
         FIG. 2  is a sectional view through a second embodiment of a regulating valve in accordance with the present invention, the valve again being shown in its open condition; 
         FIG. 3  is a sectional view on an enlarged scale taken through the vent seal shown in  FIGS. 1 and 2 ; 
         FIG. 4  is a plan view taken on line  4 - 4  of  FIG. 3 ; 
         FIGS. 5 and 6  are sectional views through alternative embodiments of vent seals; 
         FIG. 7  is a schematic view of a portable sprayer with a trigger assembly incorporating a regulating valve in accordance with the present invention; 
         FIG. 8  is an enlarged sectional view of the trigger assembly shown in  FIG. 7 ; 
         FIG. 9  is an enlarged sectional view of the pressure relief mechanism shown in  FIG. 8 ; 
         FIG. 10  is a sectional view of an alternative embodiment of a valve in accordance with the present invention; 
         FIG. 11  is an exploded view of the components of the valve shown in  FIG. 10 ; 
         FIG. 12  is a partial elevational view taken on line  12 - 12  of  FIG. 11 ; and 
         FIGS. 13A-13C  are sequential views similar to  FIG. 12  illustrating snap engagement of the cup-shaped base within the cap of the regulating valve shown in  FIGS. 10 and 11 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference initially to  FIG. 1 , a regulating valve in accordance with the present invention is generally depicted at  10 . The valve includes an outer housing having a cap  12  joined to a cup-shaped base  14  at mating exterior flanges  16 ,  18 . 
     The housing is internally subdivided by a barrier wall  22  into a head section  24  and a base section  26 . An inlet  28  in the cap  12  is adapted to be connected to a fluid supply (not shown) having a pressure that can vary from below to above a threshold level. The inlet  28  and a central port  30  in the barrier wall  22  are preferably aligned coaxially with a central axis A 1  of the valve. An outlet port  31  is provided in the cap  12 , and may be aligned on a second axis A 2  transverse to the first axis A 1 . Although the axis A 2  is shown at 90° with respect to axis A 1 , it will be understood that axis A 2  may be oriented at other angles with respect to axis A 1  in order to suit various applications of the valve. 
     A modulating assembly  32  internally subdivides the base section into a fluid chamber  23 ′ segregated from a spring chamber  23 ″. The modulating assembly serves to prevent fluid flow through the valve when the fluid pressure at the inlet  28  is below the threshold pressure. When the fluid pressure at the inlet exceeds the threshold pressure, the modulating assembly serves to accommodate fluid flow from the head section  24  through port  30  into fluid chamber  23 ′ and from there through outlet port  31  at a substantially constant outlet pressure and flow rate. Either the outlet port  31  or a downstream orifice or flow restrictor (not shown) serves to develop a back pressure in fluid chamber  23 ′. 
     The modulating assembly  32  includes a piston comprised of a hollow shell  34  and a central plug  36 . The piston is supported for movement in opposite directions along axis A 1  by a flexible annular diaphragm  38 . The inner periphery of the diaphragm is captured between the shell  34  and plug  36 . The cup shaped base  14  has a cylindrical wall segment  14 ′ received within the cap  12 . The outer periphery of the diaphragm is captured between an upper rim  15  of the wall segment  14 ′ and an inwardly projecting interior ledge  17  on the cap. The outer periphery of the diaphragm thus serves as an effective seal between the cap  12  and base  14 . 
     A stem  40  on the piston plug  36  projects through the port  30  into the head section  24 . An enlarged head  42  on the stem has a tapered underside  44  that coacts with a tapered surface  46  of the barrier wall to modulate the size of the flow path through the port  30  as an inverse function of the varying fluid pressure in the input section, with the result being to deliver fluid to the outlet  31  at a substantially constant pressure and flow rate. 
     A compression spring  48  in the spring chamber  23 ″ is captured between an underside surface of shell  34  and the bottom wall  52  of the housing base  14 . The spring urges the modulating assembly  32  towards the barrier wall  22 . When the fluid inlet pressure is below the threshold pressure, spring  48  serves to urge the diaphragm  38  against a sealing ring  49  on the underside of the barrier wall  22 , thus preventing fluid through flow from the head section  24  via port  30  and fluid chamber  23 ′ to the outlet  31 . As the fluid inlet pressure exceeds the threshold pressure, the resilient closure force of spring  48  is overcome, allowing the modulating assembly to move away from the sealing ring  49 , and allowing the modulating function of the coacting tapered surfaces  44 ,  46  to commence. An opening  50  in the bottom wall  52  serves to vent the volume beneath diaphragm  38  to the surrounding atmosphere. 
     An operating means includes a solenoid  54  fitted to the underside of the cup-shaped base  14 . The solenoid includes a magnet  56  surrounding a magnet core  58 . A rod  60  projects from the magnet core along axis A 1  into the spring chamber  23 ″ where it terminates in a flat head  62 . A closure means includes a second compression spring  64  surrounding the rod  60  and captured between the head  62  and an annular interior boss  66  on the bottom wall  52  of the base  14 . The closure force of spring  64  exceeds that of spring  48 . 
     In the condition shown in the drawing, the magnet  56  has been energized to axially withdraw the core  58 , thus pulling the head  62  downwardly against the compressive force of spring  64  and away from the underside of plug  34 . This allows the modulating assembly  32  to perform its normal pressure regulating functions as described above. 
     If the magnet  56  is deenergized, the spring  64  will serve to push the head  62  up against the bottom of plug  34  with a closure force sufficient to override the valve&#39;s normal regulating functions, resulting in the diaphragm assembly  32  being elevated to press the diaphragm  38  against the circular downwardly projecting sealing ring  49  on the barrier wall  22 . This in turn prevents fluid through flow from head section  24  via port  30  and fluid chamber  23 ′ to the outlet port  31 . A circular ledge  70  serves as a stop to limit upward movement of the core  58 , thus safeguarding the diaphragm  38  from being pressed too tightly against the sealing ring  49 . The closure force of spring  64  is sufficient to hold the diaphragm  38  against the sealing ring  49  at inlet pressures above the threshold pressure. 
     In the alternative embodiment shown in  FIG. 2 , the rod  60 ′ projects through the bottom wall  52  to terminate in a foot  63  acted upon by a lever  68  mounted for pivotal movement about a pin  69  or the like. Moving the lever up causes the rod  60 ′ to be pulled downwardly. 
     In light of the foregoing, it will be seen that the valve  10  can serve as a shut off valve by simply allowing the spring  64  to override spring  48  and maintain the diaphragm  38  of the modulating assembly  32  in sealing contact with the ring  49  on barrier wall  22 . By deactivating the closure force of spring  64 , either by energizing the solenoid  54  of  FIG. 1  or manually operating lever  68  of  FIG. 2 , the valve is conditioned to assume its normal pressure responsive regulating function at inlet pressures above the threshold level. 
     As can be best seen by additional reference to  FIGS. 3 and 4 , a gas permeable hydrophobic seal  72  overlies the vent opening  50 . The seal may comprise an expanded polytetraflouroethelene (ePTFE) film, or any other gas permeable hydrophobic membrane that allows air to escape from and reenter the spring chamber  23 ″, but that in event of failure of the diaphragm  38  and entry of liquid into the spring chamber, will prevent liquid from leaking to the exterior of the valve via the vent opening  50 . The seal  72  may be adhered or heat sealed to the bottom wall  52  as at  74 . Although not shown, the seal may be reinforced, if necessary, by an additional porous membrane, e.g., a woven fabric or the like. 
       FIG. 5  depicts an alternative embodiment of the vent seal in which a bushing  76  has been snapfitted into the vent opening  50 . The bushing is molded of a hydrophilic polymer that absorbs water and swells, resulting in closure of the restricted central vent passageway  78 . This again serves to prevent leakage in the event of failure of the diaphragm  38 . 
       FIG. 6  depicts still another alternative embodiment of the vent seal in which the vent opening  50  is located at the center of bottom wall  52 . A flexible sealing diaphragm  80  of some material that is impervious to both liquids and air is adhered or heat sealed as at  82  over the vent opening. As air pressure in the spring chamber  23 ″ varies in response to flexure of the main diaphragm  38 , the sealing diaphragm  80  will respond flexibly, while at all times maintaining a sealing relationship which will prevent liquid from escaping through the vent opening. 
     It thus will be seen that the seals  72 ,  76  and  80  serve as safeguards against leakage of liquid from the regulating valve through vent opening so in the event that the diaphragm  38  is breached. 
     The regulating valves of the present invention are adaptable to widespread usage, a non-limiting example being to stabilize the pressure and flow of the liquid sprays emitted by portable sprayers. 
     Portable sprayers include both knapsack sprayers and compression sprayers. In the conventional knapsack sprayer, a lever actuated pump is manually operated to withdraw liquid from a non-pressurized portable tank and to deliver the liquid through a wand to a nozzle from which the liquid is expelled in a spray pattern. In a compression sprayer, the tank is pressurized to achieve the same result. In both cases, the delivery pressure varies over a wide range, which affects the liquid spray pattern. Too little pressure produces excessively large wasteful spray droplets, whereas excessive pressure operates in the reverse manner to produce an overly atomized spray which can easily drift from the intended target. 
     Some attempt at control is provided by manually operating trigger assemblies interposed in the flow path between the tank and nozzle. However, experience has proven that operators are unable to operate such trigger assemblies in a manner which reliably produces substantially uniform delivery pressures and liquid flow rates to the spray nozzles. Thus, spray patterns remain erratic, resulting in wasteful excessive liquid application and/or inadequate overly atomized sprays which often drift dangerously from their intended targets. 
     In order to address these problems, and with reference to  FIGS. 7-9 , a knapsack sprayer  84  includes a tank  86  adapted to contain a liquid, typically a pesticide, herbicide or the like. A pump  88  is mounted within the tank, with an inlet submerged in the liquid, and an outlet connected to a flexible hose  90  leading to trigger assembly  94  incorporating a selectively actuated regulating valve in accordance with the present invention. The trigger assembly  94  is in turn connected to a wand  92  having a nozzle  95  at its distal end. The pump  88  is operated by a pivotal lever  96  which is manually manipulated by an operator to withdraw liquid from the tank  86  and to deliver the liquid at a variable pressure via the hose  90  to the trigger assembly  94 . Although not shown, it will be understood that the pressurized tank of a compression sprayer would operate in a similar manner to deliver fluid at a variable pressure. 
     The trigger assembly  94  incorporates a regulating valve similar to that illustrated in  FIG. 2 , with minor modifications to accommodate its positioning in the liquid flow path between the hose  90  and wand  92 . For example, the head section  24  has been reconfigured with a 90° turn to position the inlet  28  for connection to the hose  90 , the shape and pivotal connection of the operating lever  68  has been appropriately modified to serve as the trigger, and the outlet port has been connected to the wand  92 . 
     The regulating valve of the trigger assembly  94  is held closed by the force of spring  64 . The closure force of spring  64  is relieved by depressing the trigger  68 , and in response to pump pressures above the preset threshold level, the valve operates as described previously to maintain a substantially constant delivery pressure and flow rate via the wand  92  to the nozzle  95 . By maintaining a substantially constant pressure and flow rate to the nozzle  95 , the selected spray pattern remains stable irrespective of variations in the pressure and flow rate of the liquid exiting tank  86 . 
     The regulating valve of the trigger assembly  94  may be additionally modified to include pressure relief means for relieving residual internal pressures in the head section  24  when the valve is closed and either disassembly is required for cleaning and maintenance, or when the trigger assembly is disconnected from the hose  90 . To this end, a sleeve  98  is inserted in the cap  12 . The sleeve provides a vent path  100  extending from an entry opening communicating with the head section  24  to a side exit opening  102  communicating with the fluid chamber  23 ′. A pin  104  extends through the sleeve and terminates at opposite ends in enlarged shaped closure and operating heads  106 ,  108  located respectively in head section  24  and at the valve exterior. A spring  110  serves to bias the pin to the right as viewed in the drawings, thus pulling the closure head  106  in the same direction to close off the vent path  100 , as shown in  FIG. 8 . The vent path is opened by depressing operating head  108  to shift pin in the opposite direction, as shown in  FIG. 9 , thus opening the vent path and allowing pressurized liquid in the head section  24  to be bled through opening  102  to the fluid chamber  23 ′ from which it can exit through outlet port  31  to the wand  92 . 
     With reference additionally to  FIGS. 10 and 11 , another embodiment of a regulating valve is accordance with the present invention is depicted at  94   a . The components of valve  94   a  that are the same or equivalent to those of value  94  depicted in  FIG. 8  have been identified with the same reference numerals with “a” as an added identify. 
     In this embodiment, the cap  12   a  serves as an outer housing structure. The cap  12   a  has a bottom opening  112  and an internal circular land  114  grooved to accept an O-ring seal  118 . The bottom opening  112  and circular land  114  are aligned on a central axis A 1 . The barrier wall  22   a  is separate from the cap  12   a  and has a circular rim  120  adapted to be seated in sealing engagement against the O-ring seal  118 . 
     The modulating assembly  32   a  again includes a piston comprised of a hollow shell  34   a  and a central plug  36   a . The piston is supported for movement along axis A 1 , by a flexible diaphragm  38   a . The inner periphery of the diaphragm is captured between the shell  34   a  and plug  36   a , and the outer periphery of the diaphragm has a beaded edge captured in an internal groove in a cylindrical skirt  122  having a circular bottom edge  124 . 
     A preassembled first subassembly  126  includes the shell  34   a , central plug  36   a , diaphragm  38   a , skirt  122 , barrier wall  22   a  and the stem  40   a.    
     A preassembled second subassembly  128  includes the cup-shaped base  14   a , compression springs  48   a  and  64   a , and the operating rod  60   a.    
     The valve  94   a  is assembled by first seating the O-ring seal  118  in the groove  116  of the interior land  114 . The first subassembly  126  is then inserted through bottom opening  112  of the cap to seat its rim  120  against the O-ring seal  118 . 
     A compressible annular seal  130  is then inserted via opening  112  and located against the bottom of the diaphragm  38   a.    
     The second subassembly  128  is then inserted through bottom opening  112 . As shown in  FIG. 12 , the interior wall of the cap  12   a  is provided with oppositely disposed vertical grooves  132  leading to horizontal grooves  134 . The grooves  134  have ramped bottoms  136  leading to notches  138 . The cup-shaped base  14   a  has oppositely disposed radially projecting ears  140 . 
     As the second subassembly  128  is inserted, the ears  140  of the cup-shaped base  14   a  enter the vertical slots  132  ( FIG. 13A ). When an internal ledge  141  adjacent to the upper rim of the cup-shaped base  14   a  initially contacts the seal  130 , the ears  140  are positioned as shown in  FIG. 13B . The cup-shaped base is then rotated to shift the ears up the ramped bottoms  136  and into snapped engagement in the notches  136 , as shown in  FIG. 13C . The second subassembly is then securely locked in place, with the seal  130  compressed between the underside of the diaphragm  38   a  and the ledge  141 . 
     The trigger  68   a  may then be operatively connected to the cap  12   a  and rod  60   a′  to complete the assembly. 
     It will be understood that the second subassembly  128  may be secured in place by other means, including for example solvent welding or a threaded connection. Preassembly of the first and second subassemblies advantageously simplifies final assembly of the regulating valves.