Abstract:
A pressure assisted toilet flush cartridge that reduces noise output by controlling water flow. One aspect of the noise reduction is to reduce the initial discharge increase in flow rate. Another aspect is to create a vortex in discharge water to reduce cavitation and quiet the discharged water flow through the bowl.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to a pressure assisted toilets, and more specifically to a flush cartridge for a pressure assisted toilet.  
       BACKGROUND OF THE INVENTION  
       [0002]     A pressure assisted toilet system typically includes a vessel, a supply system and a flush cartridge. The supply system typically includes a backflow prevention and a pressure regulator to ensure that the vessel is maintained below a desired pressure. Since the vessel is fully sealed, it retains the supply pressure after each flush cycle refill. This supply pressure, typically 45-55 psi, pressurizes the pressure tank to its prescribed level and provides a motive force for a subsequent flush of a toilet bowl. Prior art pressure assisted toilet systems are found in U.S. Pat. Nos. 4,223,698, 5,361,426, and RE37,921 the disclosures of which are hereby incorporated by reference in their entireties.  
         [0003]      FIG. 1  illustrates a prior art pressure assisted toilet system  20 . System  20  is typically encased in an outer vitreous china housing  22 , a vessel  24  having a discharge outlet  28  and an inlet  30 , and a flush valve cartridge  36 . Flush valve cartridge  36  includes a flush valve  38  having a seal  40 , a top flange  42 , and an escape hole  44  formed therein, a flush valve enlargement  46  interposed through and sealing with the escape hole  44 , and a flush valve spring  48 . Seal  40  of flush valve  38  seats against discharge outlet  28  in order to allow pressure tank  24  to fill with water. When ready to be flush, upper chamber  47  contains both water and air compressed by the pressure To flush system  20 , an actuation lever urges valve enlargement  46  downward, which permits water (and air) to flow through escape hole  44 , thereby reducing the pressure above flush valve  38  within cartridge  36 . With this pressure reduced, flush valve  38  is forced upward by the pressure differential created between the tank  24 , and the area above the flush valve. As the flush valve lifts, water is discharged through discharge outlet  28 .  
         [0004]     A disadvantage of the prior art pressure assisted toilet system is that the noise generated during flushing has restricted its use in residential applications where excessive noise is undesirable. This noise is partially due to the rapid change in water flow rate, cavitation, and flow direction. Additionally, multiple parts are required to flush prior art toilets, thus adding to the expense of these systems. What is needed, therefore, is a pressure assisted toilet system that controls the flow of water such that noise is reduced to more acceptable levels.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention relates to reducing the noise output of a pressure assisted toilet. The inventor has found that reducing the rate of initial water flow during a flush and swirling the water discharge from the pressure tank to the bowl individually reduce undesirable noise, and that a combination of these two reduce noise even further when compared to units such as, for example, the U.S. Pat. No. 4,223,698 Patent.  
         [0006]     An embodiment of the pressure assisted toilet flush cartridge includes a generally cylindrical housing having a top end, a bottom end, an internal surface and a discharge aperture having a first predetermined area. The cartridge further includes a flush valve interposed within the housing and having a top flange, a generally conical hollow body with a top flange opening, and a lower extension, where the flange and the internal surface define a generally annular gap having a second predetermined area, and where the first predetermined area is larger than the second predetermined area.  
         [0007]     Another embodiment of the present invention provides a flush valve for a pressure assisted toilet that includes a top outer edge circumscribing a predetermined area, a flush valve seal selectively in sealing contact with a vessel outlet and a generally hollow body connecting the top outer edge and the valve seal. The body has an opening and contains a predetermined volume of water, where the volume of water provides a motive force to assist reseating the flush valve seal to seat with a vessel outlet.  
         [0008]     A further embodiment includes method of reducing noise in a pressure assisted toilet that includes imparting a swirling effect in a fluid discharged from the pressure tank to create a vortex. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:  
         [0010]      FIG. 1  is a sectional elevation view of a prior art pressure assisted flush system including the flush cartridge.  
         [0011]      FIG. 2  is a similar sectional elevation view as in  FIG. 1  except that a flush cartridge in accordance with an embodiment of the present invention has replaced the prior art version  
         [0012]      FIG. 3  is an enlarged partial sectional elevation view of the flush cartridge of  FIG. 2 .  
         [0013]      FIG. 3A  is an enlarged sectional elevation of the flush cartridge of  FIG. 2 .  
         [0014]      FIG. 3B  is an enlarged sectional elevation view similar to  FIG. 3A , illustrating an alternate embodiment of a portion of the flush cartridge.  
         [0015]      FIG. 4  is a sectional view of a conceptual actuator cartridge for the flush cartridge of  FIG. 2 .  
         [0016]      FIG. 5  is a graphical depiction of flow/volume results of a prior art flush cartridge.  
         [0017]      FIG. 6  is a graphical depiction of flow/volume results of an embodiment of a flush cartridge of the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]      FIG. 2  illustrates a pressure assisted toilet flush system  70  in accordance with an embodiment of the present invention. The system  70  includes a vessel, or pressure tank,  74  having a discharge outlet  78  and an inlet  80 , and a flush cartridge  82 . Discharge outlet  78  is preferably defined in part by a frusto-conical interior surface  84  and a generally cylindrical surface  86 , as discussed below.  
         [0019]     With reference to  FIGS. 2 and 3 , flush cartridge  82  includes a jacket, or outer housing,  88 , a flush valve  90 , and a top cap  92 . Outer housing  88  includes a cylindrical body (or jacket)  94  that extends from a top end  96  to a bottom end  98 , and an internal surface  100 . Top end  96  defines a larger inside diameter than bottom end  98 , and internal surface  100  is accordingly tapered from top end  96  to bottom end  98 . Internal surface  100  includes a retaining element  104  disposed thereon and extending inwardly from the internal surface  100 . Preferably, retaining element  104  is three equally spaced retaining lugs formed on the internal surface during forming of outer housing  88 .  
         [0020]     The flush valve  90  includes a seal retaining portion  108 , a seal  110 , a top flange  112 , a generally hollow frusto-conical body  114  extending therebetween, a lower portion  116  extending below the seal  110 , and a top flange opening  120  that extends from body  114  past top flange  112 , thus providing a hole for filling body  114  of flush valve  90 , as discussed below. Preferably, seal  110  is a conventional o-ring that is restrained within seal retaining portion  108  and extending radially therefrom in sealing contact with discharge outlet  78  when flush valve  90  is closed, as discussed in greater detail below. Top flange  112  includes a top outer edge  118  that defines a predetermined area.  
         [0021]     A generally annular gap  122  is located between top outer edge  118  and internal surface  100 . Gap  122  increases slightly as flush valve  90  rises within outer housing  88  due to the taper of internal surface  100 . Gap  122  allows fluid to pass from pressure tank  74  to flush cartridge  82 , as discussed below.  
         [0022]     Lower portion  116  is illustrated with a helical groove  126  formed therein. Helical groove  126  is illustrated with a semi-circular section, although any suitable section may be formed on lower portion  116 . The effective width, W of helical groove  126  increases as helical groove  126  extends away from seal retaining portion  108 . As best seen in  FIG. 3 , helical groove  126  has an effective width W 1  at the end closest to seal retaining portion  108 . Helical groove  126  has an effective width W 2  at about the midpoint of helical groove  126  and an effective width W 3  adjacent the end that is opposite seal retaining portion  108 . W 3  is greater than W 2 , which is greater than W 1 . Preferably, W 3  is about 50% greater than W 1 . Varying the size of the semi-circular passages of helical groove  126  varies both the effective area of gap  124  and the initial discharge flow rate and thus varies the rate of lift and the circularity of water into the bowl adjacent generally cylindrical surface  86 , as discussed below. With reasonable extremes, the more circularity, the greater the flow noise reduction.  
         [0023]     While body  114  is described as being frusto-conical shaped, body  114  may be any suitable shape that retains fluid and connects top flange  12  to seal retaining portion  108 . Flange opening  120  allows water to enter body  114  while body  114  retains the water to provide a downward force (illustrated as D in  FIGS. 2 and 3 ). Top cap  92  includes a top passageway  130  extending there through and connecting outer housing  88  with an actuation port  132 . The actuation of flush valve  90  via actuation port  132  is discussed with reference to  FIG. 4 , below.  
         [0024]     With specific reference to  FIG. 3A , a generally annular gap  124  is located between generally cylindrical surface  86  and lower portion  116  adjacent width W 1  of helical groove  126 . Gap  124  allows water to travel from pressure tank  74  to the bowl (not shown). Gap  124  controls the discharge flow rate from pressure tank  74  as discussed in greater detail below.  
         [0025]     The area of passageway  130  ( FIG. 3 ) is greater than the combination of the area defined by gap  122  ( FIG. 3 ) and the area defined by gap  124  (adjacent width W 1 ,  FIG. 3A ). Preferably, the area of passageway  130  is at least 20% greater than the combination of the area defined by gap  122  and the effective area defined by gap  124 .  
         [0026]      FIG. 3A  illustrates the lower portion  116  of  FIG. 2  with helical groove  126 .  FIG. 3B  illustrates an alternate embodiment where a lower portion  116 ′ includes a helical protrusion  126 ′. Helical protrusion  126 ′ creates an outwardly extending fin that imparts a swirling effect within the water discharged from pressure tank  74   
         [0027]      FIG. 4  illustrates a simple actuator assembly  140 . Actuator assembly  140  includes an actuator body  142  having an inlet  144 , an outlet  146 , a cylindrical interior surface  148 , and an endcap  150 . Endcap  150  has a plunger  152  extending there through and connects an actuator handle  160  with a grommet seal  162 . Plunger  152  has an elastomeric cup seal  164  attached thereto with a return spring  166  extending between. Actuator handle  160  is rotatable with respect to plunger  152  via pin  170 . Actuator handle  160  includes an actuation surface  172  that defines a generally equiangular spiral. That is, actuation surface  172  is curved such that distance H is greater than distance G. Inlet  144  is in fluid communication with the actuation port  132 . Outlet  146  is open to the atmosphere within china housing  72  or can be connected to the vessel&#39;s outlet below seal  110 . While actuator assembly  140  can be made of any suitable material, acetal plastic would be preferred.  
         [0028]     When installed, system  70  is filled with water through inlet  80 . The American National Standard mandates that the typical residential water pressure range between 20 psi to no more than 80 psi. Preferably, a pressure relief valve (not shown) is located in the water line between a water source and inlet  80  to restrict inlet water pressure to the desired pressure (usually around 25 psi). After filling, vessel  74  is pressurized to the inlet water pressure setting. This tank pressure urges seal  110  into a binding contact with discharge outlet  78  and grommet seal  162  into a binding contact with outlet  146 . Since air is compressible and water is not, as vessel  74  refills after being flushed, the air within the vessel  74  and flush cartridge  82  is compressed into flush cartridge  82 . During the first fill, some water will pass through gap  122  and enter body  114 . When the pressure within vessel  74 , flush cartridge  82 , and actuation assembly  140  equalize, flow into the assembly ceases.  
         [0029]     In operation, an operator rotates actuation handle  160  such that grommet seal  162  is unseated from outlet  146 . This releases compressed fluid from actuator assembly  140  and outer housing  88  such that the pressure above flush valve  90  is reduced and falls below the pressure within vessel  74 . The pressure above flush valve  90  falls below the pressure within vessel  74  because the area of passageway  130  is greater than the area defined by gap  122  plus the area defined by gap. The relationship between outlets  130  and  146  to gaps  122  &amp;  124  is critical because if their combined area is too close to equal, the flush valve&#39;s lift will be restricted causing an insufficient discharge flow rate to cause proper extraction of the water closet bowl. fluid released through outlet  146  flows into the china housing (not shown) and eventually through a drain passageway into the water closet bowl.  
         [0030]     The greater pressure below flush valve  90  causes flush valve  90  to rise. When flush valve  90  rises, seal  110  unseats from discharge outlet  78 , thereby permitting water from vessel  74  to escape through discharge outlet  78 . After the majority of water within pressure tank  74  has discharged through discharge outlet  78 , thereby reducing the pressure within pressure tank  74 , flush valve  90  falls due to the force of gravity and seal  110  reseats on discharge outlet  78 . Because the water within body  114  of flush valve  90  is retained, this creates an extra force that ensures that the flush valve falls, or returns to a seated position. Flush valve lower portion  116  ensures that the flush valve  90  remains centered for proper seating and sealing. As pressure tank  74  refills, pressure within pressure tank  74  increases, thereby ensuring a proper seat between seal  110  and discharge outlet  78 , and grommet seal  162  and outlet  146 .  
         [0031]     Helical grooves  126  divert the water flowing through gap  124  into a swirling pattern, or vortex, as a portion of the flowing water flows within each helical groove  126 . As flush valve  90  begins to lift from its seat on surface  84 , a limited amount of water is allowed to flow through discharge outlet  78  as the effective area defined by gap  124  is limited by dimension W 1  of helical grooves  126  and the clearance between surface  86  and lower portion  116 . As flush valve  90  continues to rise, the effective area defined by gap  124  increases as the width of helical grooves increase, thereby permitting greater flow. This characteristic of flush valve  90  results in a gradual increase in flow of water through discharge outlet  78  as flush valve  90  rises.  
         [0032]     As best seen in  FIG. 5 , a prior art flush valve, such as the flush valve disclosed in U.S. Pat. No. 4,223,698, without a helical groove formed on a lower portion, and installed on a major manufacturer&#39;s pressure-assisted bowl permits an initial spike in discharge flow that results in a maximum discharge flow of 57 gpm within 0.1 second after flushing. Of special interest is that the initial increase in flow rate of water discharged spikes as the flush valve is opened. At a tank test pressure of 50 psi and background noise level of 40 db, the operation illustrated in  FIG. 5  was measured at 84.2 db.  
         [0033]      FIG. 6  illustrates a similar flush valve with helical groove  126  formed on a lower surface extending through the discharge outlet  78  when the flush valve  90  is in the unseated position to restrain the maximum discharge flow to 46 gpm at approximately 0.2 seconds after flushing. When compared to  FIG. 5 , the initial increase in flow rate is more gradual, thereby reducing the flow noise. This gradual increase in flow rate is due, at least in part, to the width W 1  of helical groove  126  being less than the width W 3 . Since the width W 1  makes the effective area of gap  124  less as the flush valve  90  begins to rise, the volume of water permitted through discharge outlet  78  in about the initial second of flow is less than the volume of water permitted. Also, because of the changed relationship between inflow and outflow areas, the duration of discharge above 20 psi is extended, thus allowing improved extraction capability. At a water supply test pressure of 50 psi and background noise level of 40 db, the operation illustrated in  FIG. 6  was measured at 78.0 db. The graphical representations of  FIGS. 5 and 6  illustrate that the initial increase in flow rate of water discharged and existence of backpressure affect noise levels.  
         [0034]     Additionally, the vortex imparted into the flow illustrated in  FIG. 6  reduces cavitation immediately past the lower portion  116  as the pressure is reduced due to the increase in area for water flow, thereby reducing noise. Also, the vortex flow through the inner areas of the bowl (not shown) reduces noise associated with normal pressurized water flow through a pressure assisted toilet bowl.  
         [0035]     While the invention has been described with respect to specific examples including preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques that fall within the spirit and scope of the invention as set forth in the appended claims. Specifically, bowl tolerances and hydraulic designs may effect the overall noise levels during a flush.