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CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    Not applicable. 
       STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates to toilets, and more particularly to valves controlling the outflow of waste from a toilet bowl to a toilet trap. 
         [0004]    Although flushing type toilets aid in the sanitary disposal of human excrement, their level of water usage is of concern. A typical toilet includes a valve upstream of the toilet bowl, such as at the bottom of a water storage tank. When the toilet is flushed, the valve in such a water tank opens, and the tank water is able to flush into the toilet bowl. 
         [0005]    However, with these conventional toilets, there is typically a delay between the beginning of the flushing cycle and the time that most of the crude waste has been removed from the bowl. Thus, there can be an undesirably large amount of flushing water required to just move the main waste out of the bowl, and a further amount is needed to provide the final rinse. 
         [0006]    One approach for reducing this level of water usage is to provide an outlet valve immediately downstream of the toilet bowl outlet that is configured such that when it is opened most of the waste in the bowl can drop out of the bowl regardless of any new flush water entering the bowl. An example of this approach is depicted in U.S. Pat. No. 279,048. 
         [0007]    However, such valves sometimes result in clogging, maintenance or wear problems. Also, they may be expensive to produce or install, or be unreliable over prolonged use, particularly when closure is directly into the face of the bowl discharge outlet flow. 
         [0008]    U.S. Pat. No. 5,345,618 teaches a trap valve connected to a toilet bowl discharge outlet where a sphere segment gate is caused to rotate on an axis that is also the center of radius for the sphere. This provides a sliding closure of the discharge outlet. A problem with this design is that as the spherical gate rotates across the sealing element or gasket, the gate is continuously abrading the gasket, which wears the gasket and can lead to a loss of fluidic seal at the valve gate. Further, the bowl outlet which is closed by the gate, is positioned in a horizontal plane which causes the leading edge of the gate to start closing the orifice from an approximate 9 o&#39;clock position to beyond a 3 o&#39;clock position. This involves some movement during the closure against the gravity force of the bowl waste. 
         [0009]    Other examples of trap valves and valves with sphere segment gates are disclosed in U.S. Pat. Nos. 289,495, 3,214,772, 3,599,248, 3,885,771, 3,926,407, 4,164,343, 6,212,700, 5,345,618, 6,332,229; as well as U.S. patent application 2005/0211942. However, notwithstanding these developments, a need still exists for improved toilet trap valve assemblies, particularly those which facilitate flushing with reduced amounts of water. 
       SUMMARY OF THE INVENTION 
       [0010]    In one aspect the present invention provides a toilet having a bowl with a lower discharge outlet, a trap in fluid communication with the discharge outlet, and a trap valve positioned to control outflow from the discharge outlet to the trap. The trap valve has a valve housing having an entry, an exit, and a cavity connecting the entry and exit. 
         [0011]    There is a gate valve positioned in the cavity and pivotable using linkage that extends from outside the housing to the gate valve. There is also a sealing gasket (preferably positioned adjacent the entry), so that the gate valve is pivotable from a first position blocking the entry and essentially closing off outflow from the discharge outlet, to a second position permitting flow from the discharge outlet to the trap, and so that the gate valve can begin closing off the entry when a lead edge of the gate valve is within 25° of vertical. 
         [0012]    In preferred forms the valve housing is in the form of a cartridge having two clamshell parts defining the cavity. The gate valve can be in the form of a spherical segment having a radius of curvature extending from a center of curvature, such that the gate valve is pivotable about a center of rotation offset from said center of curvature. 
         [0013]    Pivoting of the gate valve can be initiated as part of a flush cycle of the toilet, and the trap can have a normal trap water level to restrict back flow of sewer gases to the bowl, where the gate valve is positioned so as to be above that water level. 
         [0014]    In another aspect the invention provides such a trap valve, albeit particularly where it is in the form of a cartridge suitable to be connected at one end to a toilet bowl discharge outlet and at another end to a toilet trap. 
         [0015]    In another aspect the invention provides a toilet including a bowl having a lower discharge outlet, a trap in fluid communication with the discharge outlet, and a trap valve positioned to control outflow from the discharge outlet to the trap. The trap valve has a valve housing having an entry, an exit, and a cavity connecting the entry and exit. A gate valve is positioned in the cavity and pivotable using a linkage that extends from outside the valve housing to the cavity. 
         [0016]    A sealing gasket is positioned adjacent the valve housing entry, wherein the gate valve is pivotable from a first position essentially closing off outflow from the discharge outlet to a second position permitting flow from the discharge outlet to the trap. The gate valve is linked to the linkage via a ball and socket arrangement. 
         [0017]    In some embodiments, the present invention advantageously minimizes the tendency of the gate valve to abrade the sealing gasket, and helps to avoid leakage by placing the gate valve above the normal trap water level. Further, in those embodiments the closure requires little power as the gate is closing initially largely transversely to the flow out from the bowl, rather than directly upward. 
         [0018]    In other embodiments a ball and socket joint is provided between the gate valve and its linkage so that as the gate valve closes it can correct for manufacturing tolerances or minor waste along the seal. 
         [0019]    Additionally, should any maintenance issue arise with respect to the trap valve which requires replacement of the valve cartridge, or a component of it, the valve cartridge, or its component, can be replaced without having to dispose of the bowl or trap. 
         [0020]    These and still other advantages of the present invention will be apparent from the detailed description which follows and the accompanying drawings. Hence, the following claims should be looked to in judging the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a vertical cross-sectional view through a portion of a lower toilet bowl and trap assembly constructed in accordance with the present invention; 
           [0022]      FIG. 2  is an exploded perspective view of a trap valve cartridge depicted in  FIG. 1 ; 
           [0023]      FIG. 3  is a perspective view of a gate valve of the  FIG. 2  trap valve, the gate valve being viewed from a different perspective than as shown in  FIG. 2 ; 
           [0024]      FIG. 4  is an enlarged, fragmentary, cross-sectional view of a portion of  FIG. 1 ; 
           [0025]      FIG. 5  is a further enlarged fragmentary cross-sectional view of a portion of  FIG. 1 , albeit now showing the gate valve in the process of closing; 
           [0026]      FIG. 6  is a view similar to  FIG. 5 , but with the gate valve now fully closed; 
           [0027]      FIG. 7  is a view similar to  FIG. 1 , but of a second embodiment where the cartridge is attached to the bowl at a slightly different angle; and 
           [0028]      FIG. 8  is a perspective, cross-sectional view of another embodiment of a valve according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    Referring first to  FIG. 1 , there is shown the lower portion of a toilet generally  10 , where there is the usual toilet bowl  12  with discharge outlet  14 . Toilet  10  can otherwise be of a conventional construction. 
         [0030]    For example, the toilet above the discharge outlet could have a structure analogous to that of U.S. Pat. No. 5,345,618, the disclosure of which is incorporated by reference as if fully set forth herein. Thus, there can be electrical or mechanical flush controls, including linkages from those controls to the trap valve  18 . Alternatively, one could move the trap valve manually. 
         [0031]    In any event, in the present embodiment, there is also a trap  16  in fluid communication with discharge outlet  14 , and a trap valve  18  located downstream of bowl  12  and upstream of trap  16 . Toilet  10  preferably includes a flange  20  near the bottom of bowl discharge outlet  14 , and other connecting elements such as fasteners for connecting to the cartridge form trap valve  18  at flange  22 . 
         [0032]    Trap  16  has a normal trap water level  24  for preventing return of sewer gas, and can be connected to trap valve  18  at collar  26  with a flexible piece of rubber and/or other connector elements such as clamps (not shown). Trap valve  18  permits the passage of waste and fluid from bowl  12  to trap  16  when in the  FIG. 1  open position. 
         [0033]    Referring to  FIGS. 1-3 , trap valve  18  includes a first clamshell housing part  28 , and a second generally mirror image clamshell housing part  30  connectible to first clamshell housing part  28 . There is also a pivotable gate valve  32  mounted inside a cavity defined by the first and second clamshell housing parts  28 / 30 . 
         [0034]    This cavity has an inlet orifice/entry  34  (see  FIG. 1 ) which includes at least one gasket  36 ,  38 ,  40  surrounding inlet orifice  34 . Pivotable gate valve  32  is positioned in the cavity so as to be able to move between a first closed position blocking inlet orifice  34  between flushes ( FIG. 6 ), and an essentially open position ( FIG. 1 ), and then a return position beginning to close off flow (as shown in  FIG. 5 ). 
         [0035]    Pivotable gate valve  32  preferably includes an essentially spherical contact segment  42  which has a radius of curvature  44  ( FIG. 5 ) extending from a center of curvature  46 . Pivotable gate valve  32  rotates about a center of rotation  48  offset from center of curvature  46 , which results in a slightly eccentric rotation of gate valve  32  relative to its closure position. This allows spherical contact segment  42  to contact the sealing surface of gasket  36  fully only when gate valve  32  is in approximately the  FIG. 6  position. 
         [0036]    This means that the gate valve will not continuously scrape across the gasket  36  throughout the full swing of the gate valve closure. Rather, it closes in on the gasket sealing surface in an eccentric manner, thereby reducing wear and maintenance issues. 
         [0037]    Moreover, the leading edge of the gate  50  cuts across the water exiting from the bowl transversely, rather than pushing up perpendicularly to the flow. This facilitates closure by helping to minimize the needed force to fight the effects of gravity. 
         [0038]    Most preferably, pivotable gate  32  has a leading edge  50  approximately between +40° and −40° (most preferably between +25° and −25°) from vertical when gate valve  32  is in the  FIG. 4  position. Thus, leading edge  50  is approximately vertical when gate  32  begins to reduce the opening during closure. 
         [0039]    As shown in  FIGS. 1-6 , gate valve  32  can comprise an approximately quarter spherical segment  42 . Further, pivoting of the gate valve  32  can be caused by movement of a stem  52  that extends outside of housing parts  28 ,  30  and into the cavity. 
         [0040]    Pivotable gate valve  32  can be positioned so as to always be above normal trap water level  24 . This helps avoid having the trap valve components soak in sullied water between flushes, thereby reducing maintenance and leakage concerns. Also, waste does not tend to collect between the gate valve  32  and its cartridge cavity pocket. This reduces the resistance to opening which would occur if that would happen. 
         [0041]    Stem  52  is connected to sockets  54  so that during a flushing cycle one trips a flush initiator connected to stem  52 , which ultimately pivots the gate valve  32  out of the closed position. This permits waste to rapidly evacuate through inlet  34  of the valve cartridge. It is preferred that the start of the flush water be delayed slightly to permit most of the evacuation to occur before clean flush water starts to rinse the bowl. 
         [0042]    After a defined period, trap valve  18  can have its gate valve  32  be caused to return to the  FIG. 6  closed position, and preferably be latched in that position so that some water will remain in the bowl above gate valve  32  between flushes. The inlet water will then be shut off, ending the flush cycle. 
         [0043]    In the embodiment shown in  FIG. 7 , toilet  60  depicts trap valve cartridge  18 A being at a slightly different angle of installation when compared to  FIG. 1 . Other elements are substantially the same as in  FIG. 1 , and hence are numbered in similar fashion. 
         [0044]    In the embodiment shown in  FIG. 8 , a trap valve  80  is positioned to control outflow from the discharge outlet of a toilet to the trap of the toilet. Trap valve  80  includes a housing  81  having an entry, an exit, and a cavity connecting the entry and exit. A sealing gasket  82  is positioned adjacent the valve housing entry. A gate valve  83  is positioned in the cavity and is pivotable using a linkage  85  that extends from outside the housing  81  to the cavity. Gate valve  83  is pivotable from a first position essentially closing off outflow from the discharge outlet to a second position permitting flow from the discharge outlet to the trap. There is an arm  84  connected to linkage  85 , the arm being pivotably connected to gate valve  83 . 
         [0045]    In the embodiment shown in  FIG. 8 , the connection between arm  84  and gate valve  83  is a ball  86  and socket  88  arrangement. This allows the position of gate valve  83  to adjust as it is pressed against sealing gasket  82  in the closed position, and therefore increases the chances that the gate valve  83  seals (by making it less susceptible to assembly tolerances and minor debris on the seal). 
         [0046]    Regardless of the embodiment, the present invention facilitates use of a trap valve to control toilet bowl evacuation. Maintenance concerns relating to wear on a sealing gasket are reduced by the eccentric closure. The positioning of the gate valve near vertical as the closure gate starts in some embodiments facilitates closure in the face of the weight of the bowl material. Positioning of the gate valve above the trap water level further reduces maintenance issues and helps with reliability. 
         [0047]    The cartridge valve can be made of metal or plastic components. 
         [0048]    While preferred embodiments of the present invention have been disclosed, it should be appreciated that still other modifications and variations to the preferred embodiments will be apparent to those skilled in the art, and are intended to be within the spirit and scope of the invention. For example, while the cartridge valve is preferably used with a ceramic bowl and trap, it can also be used with toilet components made of other materials (e.g. metallics; plastics). Further, the angle of installation of the trap valves  18 / 18 A and gate  32  can vary somewhat. 
         [0049]    Therefore, the present invention is not to be limited to just the described most preferred embodiments. To ascertain the full scope of the invention, the claims which follow are referenced. 
       INDUSTRIAL APPLICABILITY 
       [0050]    The invention provides toilets which have improved trap discharge valves.

Summary:
A valve for a toilet includes an inlet and a gate configured to prevent fluid flow through the inlet. The gate includes an at least partially spherical surface and is configured to pivot eccentrically relative to the spherical surface.