Abstract:
A control stop for a flush valve for a urinal or toilet fixture includes a housing defining a flow chamber divided by a valve seat into inlet and outlet sections. A valve structure is biased toward the valve seat by a spring applying a valve closing spring force. The housing is sealed by a diaphragm, and the diaphragm covers the movable valve structure, isolating it from water flowing through the housing. The diaphragm does not impede valve structure movement, and the closing spring force establishes a threshold water supply pressure for opening the control stop during increasing pressure following a no or low supply pressure condition. A plurality of control stops may supply a bank of flush valves and fixtures, and open in a cascading sequence during increasing pressure as a result of having springs with different closing spring forces.

Description:
FIELD OF THE INVENTION 
     The present invention relates to improvements in control stops and to improvements in flushing systems including multiple control stops. 
     DESCRIPTION OF THE PRIOR ART 
     Flushing systems for urinal and toilet fixtures in applications such as commercial structures normally include a flush valve supplying water to flush each fixture. The flush valve is conventionally a flushometer type, capable of supplying a measured volume of water for the flushing operation. A device known as a control stop, or supply stop, is typically used to supply water to each flush valve. The control stop provides a flow resistance preventing excess water flow at elevated inlet pressures, thereby avoiding noise and improper flushing action. The control stop also prevents reverse flow in the event of supply pressure loss. The control stop can also function as a manually operated shut off for repair or replacement of the downstream flush valve or fixture. 
     An example of a typical control stop or supply stop is disclosed in U.S. Pat. No. 3,556,137. This device functions as a check valve with a valve plug biased by a relatively light spring toward a valve seat located at the inlet of the control stop. The relatively low forward cracking pressure resulting from the weak spring permits the flush valve to be supplied with water at low supply pressures. Because a typical flushometer valve requires substantial inlet pressure to operate to the fully closed condition, the supply of low pressure water to the valve permits the flush valve to run on or dribble. This wastes water, and can lead to flooding if the fixture drain is blocked. The typical supply or control stop has additional disadvantages because it requires a large quantity of material and has a large number of parts that must be manufactured and assembled. 
     Another known control stop is disclosed in U.S. Pat. No. 4,462,444. Both of these known control stop structures rely on sliding seals such as O-rings to permit movement of a valve structure while sealing and retaining water in the housing of the control stop. With this type of seal, movable components of the valve structure are exposed to water flowing through the control stop. This can lead to corrosion and leakage problems, and also limits the choice of materials available in manufacturing to materials that are unharmed by exposure to water. In addition, the use of sliding contact seals causes friction that impedes movement of the valve structure, leading to the need for larger valve biasing springs. Friction decreases sensitivity, preventing a consistent, accurate relationship between water pressure and control stop actuation. 
     In multiple fixture installations, a bank of fixtures, each having a control stop and a flush valve, are supplied in common from a single water supply header. A difficulty with this arrangement is that each flush valve requires a substantial supply pressure in order to operate from the open to the closed condition. Often the common water supply cannot simultaneously provide a sufficient supply of water for an entire bank of flush valves. For example, in the event of a water supply interruption when several flush valves are open, when the supply of water is resumed the valves cannot close. To overcome this problem, maintenance personnel must close the control stops supplying the bank of flush valves, and manually open them in sequence so that the water supply is sufficient for each flush valve in sequence to operate through a flush metering cycle and recluse. 
     SUMMARY OF THE INVENTION 
     A primary object of the present invention is to provide an improved control stop for supplying water to a flush valve in fixture flushing systems. Other objects are to provide a control stop that acts as a flow interrupter at low pressures and has a quick opening operation as water supply pressure increases; to provide a control stop wherein the moving valve structure is not exposed to water flowing through the device; to provide a control stop having little friction impeding movement of the valve structure; to provide a control stop using a minimum amount of material and a small number of parts; and to provide a control stop overcoming disadvantages of control stops used in the past. 
     Another object of the invention is to provide an improved flushing system having a bank of fixtures supplied from a common supply header through control stops and flush valves. Other objects are to provide a flushing system in which manual sequential control stop operation is not required for starting up a system with several open flush valves; to provide a flushing system in which different control stops are operated to the open condition at different water supply pressures; and to provide a flushing system overcoming disadvantages or flushing systems used in the past. 
     In brief, in accordance with the present invention, there is provided a control stop for connection between a pressurized water source and a flush valve. The control stop includes a housing defining an elongated flow chamber having a longitudinal axis. A valve seat is located in the flow chamber. A valve structure in the flow chamber moves in the direction of the axis relative to the valve seat for controlling flow through the flow chamber. A generally hat shaped flexible diaphragm includes a brim portion connected in sealing relation to the housing and includes a crown portion enclosing the valve structure. 
     In brief, in accordance with another aspect of the invention, there is provided a flushing system for a plurality of urinal and/or toilet fixtures. The flushing system includes a plurality of flush valves, each connected to supply water to one of the fixtures and a plurality of control stops, each connected to supply water to one of the flush valves. Each of the flush valves has a threshold inlet supply pressure during increasing supply pressures at which the flush valve operates from closed to open position. In order that the flush valves open in sequence and not simultaneously during increasing pressure following a supply interruption, the threshold pressure of at least a first of the plurality of control stops is different from the threshold pressure of at least a second of the plurality of control stops. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The present invention together with the above and other objects and advantages may best be understood from the following detailed description of the preferred embodiment of the invention illustrated in the drawings, wherein: 
         FIG. 1  is an isometric view of a plumbing installation including a flush valve and a control stop constructed in accordance with the present invention; 
         FIG. 2  is an enlarged cross sectional view taken along the longitudinal axis of the control stop of  FIG. 1 , showing the control stop in the closed position; 
         FIG. 3  is a view like  FIG. 2  showing the control stop in the open position; 
         FIG. 4  is an exploded isometric view of the control stop; and 
         FIG. 5  is a block diagram of a plumbing system in accordance with the present invention including a plurality of flush valves and control stops. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Having reference now to the drawing, and initially to  FIG. 1 , there is illustrated a plumbing installation generally designated as  10  for flushing a urinal or toilet fixture (not shown). The plumbing installation  10  has a water supply conduit  12  through which water is supplied from a pressurized source such as a municipal or local water supply system. Conduit  12  supplies water to the inlet  14  of a control stop  16 , and water from the control stop  16  is supplied from an outlet  18  to a transfer conduit  20  and to a flush valve  22 . For a flushing operation, an operating handle  24  is displaced, and as the flush valve operates through a flush cycle, a measured quantity of water travels to the fixture through an outlet conduit  26 . The principles of the present invention may be applied to systems using flush valves other than manually operated valves, including timer operated automatic valves and user detection responsive valves. 
     The control stop  16  is constructed in accordance with the principles of the present invention, and is illustrated in detail in  FIGS. 2-4 . A housing  28  of the control stop  16  includes a body  30  and a cap  32 . The cap  32  includes an outer cap portion  34  and an inner member or insert  36 . The body and the outer cap  34  are preferably made of brass and may be chrome plated. Because the outer cap  34  is not exposed to water flowing through the housing  28 , it may be made of 360 brass if desired. The insert  36  is also not exposed to flowing water and may be made of glass filled nylon if desired. 
     The housing  28  defines an elongated interior flow chamber  38  extending in an axial direction toward an outlet port  40  provided at the outlet  18 . An annular valve seat  42  divides the chamber  38  into an inlet portion  44  and an outlet portion  46  communicating with the outlet port  40 . The valve seat  42  is defined by the edge of a cylindrical wall  48  extending in the upstream axial direction from a transverse wall  50 . An inlet port  52  extending transversely to the axis of the elongated flow chamber  38  introduces water from the supply conduit  12  and inlet  14  ( FIG. 1 ) into the inlet portion  44  of the flow chamber  38 . 
     A valve structure  54  moves toward and away from the valve seat  42  to control flow from the inlet port  52  through the flow chamber  38  to the outlet port  40 . In the closed position seen in  FIG. 2  the valve structure  54  contacts the valve seat  42  to prevent the flow of water. In the open position seen in  FIG. 3 , the valve structure  54  is spaced from the valve seat  42  and water can flow through the control stop  16 . 
     The valve structure  54  includes a valve member  56  that may be made of a wide choice of materials such as plastic because it is not exposed to water flowing through the control stop  16 . The valve member  56  has a head portion  58  generally corresponding in shape and size to the valve seat  42 , and a stem portion  60  slideably received in a guide collar  62  in an axially extending hub portion  64  of the insert  36 . The full open position of the valve member  56  is defined by contact of the stem portion  60  with an adjustable abutment set screw  66  threaded into the hub portion  64  of the insert  36 . The set screw  66  is adjusted to set the flow restriction provided by the control stop  16 . In addition, the set screw  66  is threaded fully inward to manually close the valve structure against the valve seat and shut off all flow through the control stop  16 . 
     In addition to the valve member  56 , the valve structure  54  includes a cup  68  and a diaphragm  70 . The diaphragm  70  is made of a flexible, resilient, water impervious material such as propylene rubber or nitrile rubber, and is generally hat shaped with a brim portion  72  and a crown portion  74 . The cup  68  and the diaphragm crown portion  74  are similar in shape, and, in the illustrated embodiment, generally have the shape of a closed ended right circular cylinder. The cup  68  may be made of stainless steel, and is interposed between the head portion  58  of the valve member  56  and the crown portion  74  of the diaphragm  70 . The cup  68  supports the diaphragm  70 , and the crown portion  74  has a flat circular end wall  76  that seats against the valve seat  42  in the closed position of the control stop  16 . 
     A coil spring  78  is in compression between the insert  36  and the head portion  58  of the valve member  56 . The spring  78  biases the valve structure  54  toward the closed position in which the wall  76  of the diaphragm  70  contacts the valve seat  42 . 
     The elements of the movable valve structure  54 , other than the diaphragm  70 , are isolated by the diaphragm  70  from water flowing through the flow chamber  38 . The brim portion  72  of the diaphragm  70  includes an axially extending peripheral rim portion  80 . The outer cap  34  is threaded into the end of the body  30  and captures an outer flange  82  of the insert against a positioning shoulder  84  of the body  30 . The peripheral rim portion  80  of the resilient diaphragm  70  is captured in sealing relation between the flange  82  of the insert  36  and a seal shoulder  86  of the body  30 . Because the moving parts of the control stop  16  are separated by the diaphragm  70  from the flow of water, reliability is improved and problems of corrosion and leakage are avoided. 
     In the absence of water pressure, for example upon initial installation or following a repair or replacement of a flush valve or fixture, the control stop is initially in the closed position of  FIG. 2  because the spring  78  holds the valve structure  54  against the valve seat  42 . Water supply pressure acts in the opening direction against the portion of the diaphragm radially outside of the valve seat  42 —essentially the brim portion  72 . A substantial predetermined threshold opening pressure is determined by the spring force of the spring  78 . For example, in the illustrated preferred embodiment of the invention, the spring  78  may be selected to apply a closing force of 3.5 pounds when the valve structure  54  is closed ( FIG. 2 ) and a closing force of 5 pounds when the valve structure  54  is open and the spring  78  is further compressed ( FIG. 3 ). In this configuration, the threshold supply pressure for opening the valve structure  54  is about 7.6 pounds per square inch (psi). 
     When the predetermined threshold supply pressure is reached, the closing force of the spring  78  is overcome and the valve structure  54  strokes toward moves to the open position of  FIG. 3 . As the valve structure  54  opens, the spring force increases, but the area of the diaphragm  70  exposed to supply pressure is larger, and the supply pressure required to maintain the control stop  16  in the open position decreases from the initial threshold of about 7.6 psi to about 4.7 psi. This provides a snap acting, bistable operation as the valve structure  54  reliably and quickly strokes to the full open position when the threshold pressure is reached. In this example, if supply pressure drops to a level below about 4.7 psi, the control stop returns to the closed position of  FIG. 2 . 
     The threshold pressure is large enough to assure reliable flush valve operation when the control stop  16  opens. In addition, at low pressures, the control stop acts to positively block all flow so that the flush valve is not exposed to low pressure conditions in which it may not operate reliably. 
     The diaphragm seals against leakage from the housing  28  while permitting movement of the valve structure  54  with very little resistance to valve movement. The friction resulting from an O-ring seal or other sliding seal is eliminated. As a result, the opening operation of the valve in response to inlet pressure is highly sensitive, and the control stop  16  opens reliably at the threshold pressure established by the spring force imposed by spring  78 . This spring force can be selected to accurately determine a threshold opening pressure, and this feature can be used to provide improvements in multiple flush valve systems 
       FIG. 5  illustrates a flushing system including a number or bank of eight flush valves  22 A- 22 H. Each flush valve is supplied with water from a corresponding control stop  16 A- 16 H, all preferably having generally the structure of the control stop  16  illustrated in  FIGS. 2-4 . The bank of flush valves  22 A- 22 H is supplied with water from a source  88  of pressurized water through a common header  90  connected to all of the supply conduits  12 . 
     The flush valves  22 A- 22 H require a residual pressure to keep them closed. Therefore in the event of an interruption in the water supply, some or all of the flush valves  22 A- 22 H may be in an open condition. The flush valves cannot operate through a metered flush cycle and reclose unless they are supplied with a predetermined minimum water pressure, for example, 5 psi. The header  90  and water supply  88  do not have the capacity to supply sufficient water for simultaneously operating the entire bank flush valves  22 A- 22 H through a flushing cycle. 
     In order to overcome this problem, different ones of the control stops  16 A- 16 H have different, graduated threshold supply pressures. This is accomplished by providing the control stops with springs  78  having different spring forces. The following table provides one illustration of approximate threshold pressures resulting from graduated spring forces. 
     
       
         
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Control stop 
                 Spring Force 
                 Threshold Pressure 
               
               
                   
               
             
             
               
                 16A, 16B 
                 3.5 pounds 
                 7.6 psi 
               
               
                 16C, 16D 
                   4 pounds 
                 8.7 psi 
               
               
                 16E, 16F 
                 4.5 pounds 
                 9.8 psi 
               
               
                 16G, 16H 
                   5 pounds 
                 10.9 psi  
               
               
                   
               
             
          
         
       
     
     Following a water supply interruption, as water supply pressure increases, the flush valves are operated and cycled to closed positions in a cascading sequence rather than simultaneously. In this example, the springs  78  of the control stops  16 A and  16 B apply a valve closing force in the closed position of the valve structure  54  of 3.5 pounds. When the supply pressure reaches about 7.6 psi, these two control stops  16 A and  16 B rapidly move to the open position. The source  88  and header  90  have sufficient capacity for simultaneous operation of two flush valves, and flush valves  22 A and  22 B are reliably cycled to the closed position without the need for manual control of the control stops. 
     When the supply pressure subsequently increases to the next threshold value of about 8.7 psi, the control stops  16 C and  16 D, with a closing spring force of 4 pounds, open and the corresponding flush valves  22 C and  22 D are operated through a flush cycle and close. Similarly, at the subsequent threshold supply pressure of about 9.8 psi, the control stops  16 E and  16 F, with a closing spring force of 4.5 pounds, open to operate flush valves  22 E and  22 F, and finally at a threshold supply pressure of about 10.9 psi, the control stops  16 G and  16 H, with a closing spring force of 5 pounds, open to operate flush valves  22 G and  22 H. 
     This operating principle could be employed to simultaneously operate more than two flush valves at a time, or to control a bank of flush valves to open one at a time. The sequencing of flush valve operation at increasing supply pressures could be achieved with control stops different from the control stop  16  described in detail above. However, in the control stop  16  the use of the diaphragm  70  rather than an O-ring or other sliding contact seal results in a reduction of friction. The low friction operation makes it possible for control stops with different spring forces to open reliably at different threshold pressures. It could be more difficult, to accomplish this with other known control or supply stops lacking sensitivity in the relationship between spring force and opening supply pressure. 
     While the present invention has been described with reference to the details of the embodiments of the invention shown in the drawing, these details are not intended to limit the scope of the invention as claimed in the appended claims.