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FIELD OF THE INVENTION 
     The present invention relates generally to plumbing fixtures and to the component parts that are used in them. More particularly, it relates to a flush valve for use in a toilet tank that has a valve body where the flush valve outlet is offset whereby improved flushing capacity and improved overflow capacity is realized and manufacture of the valve body is simplified. It also relates to such a valve body that can be configured for use in original toilet plumbing as provided by a manufacturer or as a replacement item for use in a wide variety of toilet tanks and fixtures as an after-market installed flush valve. 
     BACKGROUND OF THE INVENTION 
     A conventional gravity operated flush toilet has several basic components. The china components include a bowl and a tank mounted atop a rear portion of the bowl. The bowl and tank may either be separate pieces or may be molded as a single unitary piece. The plumbing components of the conventional gravity operated flush toilet include a fill valve in the tank that is connected to a water supply line, a flush valve mounted in a hole in the bottom wall of the tank that communicates with the bowl, a flapper valve that normally closes the flush valve, and a lever or push button on the outer wall of the tank that is connected with a chain or other mechanical linkage for momentary lifting of the flapper valve. This allows water stored in the tank to flow rapidly through the flush valve into the bowl to carry waste along with the water through a trap connected to the underside of the bowl and into a waste pipe connected to a sewer line, septic tank or other waste reservoir. 
     Conventional flush valves for gravity operated toilets are well known in the art. Such flush valves are generally cylindrical and provide a round valve seat for the liftable flapper valve. They are secured within a drain hole located in the bottom wall of the toilet tank from underneath the bottom wall. Typically a large nut is screwed over a male threaded lower portion of the cylindrical flush valve body, on the underside of the bottom wall of the tank. Extending upwardly from and to one side of the flush valve itself is a cylindrical overflow tube. The purpose of the overflow tube is two-fold. First, the overflow tube prevents flooding in the case of water overflow to the tank. The overflow tube thus ensures that a proper water level is maintained within the toilet tank in the condition of overflow. Ideally, the inlet of the overflow tube is set at a point where it is slightly above normal water level, but below the bottom of the flush lever nut that is located on a vertical wall of the tank for actuation of the flushing cycle. The second purpose is that the overflow tube serves as a conduit to the toilet bowl during refilling of the tank, a small amount of water flowing to the tank being diverted through the overflow tube for this purpose. This occurs when the fill valve is re-filling the tank and, via the overflow tube, the toilet bowl, the toilet bowl having been emptied during the siphoning of the water in it during the flushing action. 
     In the design of the conventional flush valve, this overflow tube is a vertically-extending circularly-tubular structure having a generally vertical axis. The flush valve itself is similarly a vertically-disposed circular structure having a generally vertical axis and also having a central aperture that is greater inner diameter as compared to the diameter of the overflow tube, the flush valve aperture having a cylindrical valve seat defining an inlet at its uppermost portion and an outlet at its lowermost portion. In this configuration, a flow passageway is defined at the bottommost portion of the overflow tube whereby a water flow continuum is created between the overflow tube, the central passageway and the outlet of the central aperture of the flush valve. Water flowing into the overflow tube from the tank flows down the overflow tube, then flows out of the tube at the passageway that is typically disposed at a right angle from the overflow tube, into the central aperture of the flush valve, and then flows through the flush valve outlet. In this configuration, the bulb of the flapper valve can severely restrict the overflow capacity of the flush valve by impinging on the flow area around the bulb, including the passageway between the overflow tube and the flush valve outlet. This becomes especially critical when an original equipment manufacturer (OEM) flapper is later replaced with a new flapper, typically manufactured by another company, to some rather arbitrary specifications. The problem is that adequate overflow capacity is completely overlooked, because the only issue in the consumer&#39;s mind is typically how to stop the flapper from leaking. If the passageway between the overflow tube and the flush valve outlet is blocked, even in part, by the flapper valve bulb, then the ability of the overflow tube to do its job is compromised. The flush valve of prior art is also rather difficult to mold as a one-piece item using conventional plastic molding processes. 
     In the view of these inventors, what is needed is a flush valve having an outlet from the central aperture that is offset from its conventional position. This configuration would place the outlet portion of the central aperture of the flush valve partly underneath the overflow tube, thereby improving overflow capacity of the flush valve. This configuration could also make the flush valve a more compact device, while also making it a high overflow capacity device. The flapper valve seat, or the cylindrical valve seat of the flush valve at the flush valve inlet, would retain its cylindrical shape so as to allow flapper valves of current manufacture to be used with the device. But the axis of the flush valve would be modified. At the inlet of the flush valve, the axis would be directed at somewhat of an angle relative to the vertical at the uppermost portion of the flush valve. At the outlet and at the lowermost portion of the flush valve, the axis would return to vertical. In this way, the lowermost portion of the flush valve would be disposed both below a portion of the overflow valve and below the inlet of the flush valve. 
     In the view of these inventors, this configuration would also make the device easier to mold. For example, the flush valve described above would eliminate the requirement of molding the lateral section of the passageway through the valve body separately, thus simplifying the mold process, reducing costs, and increasing the durability of the mold. In the conventional molding process, complicated retracting mold cores are required to be used to form the passageway. These disadvantages are avoided by offsetting the outlet of the flush valve such that the core for the bottom of the valve body and the core mold for the overflow tube meet such that an extra horizontal, or lateral, connection, or self-retracting core is not required. 
     It should also be mentioned that, in the United States, there are two basic markets for toilet flush valves, namely, the OEM market and the after-installation market. The former consists of large toilet manufacturers that assemble and sell complete gravity operated flush toilets including flush valves. The latter consists of hardware and plumbing supply stores that sell to plumbers and home owners for repair and replacement in toilets already installed in residences. Accordingly, it would be desirable to provide the offset outlet flush valve of the present invention in configurations that would allow it to be used in both the OEM and the after-installation markets. 
     Finally, it is recognized that every gravity operated flush toilet has an optimum fill level that ensures that enough water is in the tank for proper flushing without wasting water or risking incomplete waste carry out. For many years, gravity operated flush toilets in the United States had tanks with capacities of three and one-half, five gallons, or more. More recently, the Environmental Protection Agency (EPA) has mandated that low water consumption toilets be installed in all new construction and during all re-models, with a maximum water usage of 1.6 gallons per flush. Both the older high volume gravity operated flush toilets and the newer low volume gravity operated flush toilets come in a wide range of tank configurations with different optimum fill levels. Because of this, installation of after-market flush valves, which are manufactured in a pre-determined height to accommodate the deepest tank depth likely to be found, typically requires the installer to hand cut the overflow tube of the flush valve to fit. In the experience of these inventors, it would be unduly expensive to manufacture a variety of different overflow valves, each having an overflow tube of different height, to satisfy the configurations of the various gravity operated flush toilets manufactured in the United States and abroad. It is, therefore, advantageous to provide the after-installation offset outlet flush valve that is constructed in accordance with the present invention with an adjustable overflow tube that would permit plumbers and do-it-yourself homeowners to install the offset outlet flush valve and to adjust the height of its overflow tube as necessary. 
     SUMMARY OF THE INVENTION 
     Accordingly, a primary objective of the device of the present invention is to provide an offset outlet flush valve that provides improved flow capacity. It is another object to provide an offset outlet flush valve that can be used in original manufacture toilet fixtures as well as for the after market and that can be readily adapted to the tank profile of a wide variety of gravity operated flush toilets. It is still another object to provide an offset outlet flush valve that can be used with flapper valves of other manufacture such that impingement by the flapper valve bulb within the water flow continuum is minimized. It is yet another object of the device of the present invention to provide such an offset outlet flush valve that is easier to fabricate. 
     In accordance with the aforementioned objectives of the present invention, there is provided a flush valve having an offset outlet that provides better flow capacity, that is simpler to manufacture and that can be used as equipment in toilets of original manufacture and as replacement after-market devices. The foregoing and other features of the device and method of the present invention will be apparent from the detailed description that follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top, front and left side perspective view of a flush valve that is known in the art. 
         FIG. 2  is a slightly enlarged top plan view of the flush valve shown in  FIG. 1 . 
         FIG. 3  is a side elevational view of the flush valve shown in  FIG. 1 . 
         FIG. 4  is a front elevational view of the flush valve shown in  FIG. 1 . 
         FIG. 5  is a slightly enlarged and cross-sectioned side elevational view of the flush valve shown in  FIG. 1  and taken along line  5 - 5  of  FIG. 2 . 
         FIG. 6  is a top, front and left side perspective view of a first embodiment of an offset outlet flush valve that is constructed in accordance with the present invention. 
         FIG. 7  is a top plan view of the offset outlet flush valve shown in  FIG. 6 . 
         FIG. 8  is a left side elevational view of the offset outlet flush valve shown in  FIG. 6 . 
         FIG. 9  is a bottom plan view of the offset outlet flush valve shown in  FIG. 6 . 
         FIG. 10  is a front elevational view of the offset outlet flush valve shown in  FIG. 6 . 
         FIG. 11  is a left side and cross-sectioned elevational view of the offset outlet flush valve shown in  FIG. 6  and taken along line  11 - 11  of  FIG. 7 . 
         FIG. 12  is a top, front and left side perspective view of a second embodiment of an offset outlet flush valve that is constructed in accordance with the present invention. 
         FIG. 13  is a left side elevational view of the offset flush valve shown in  FIG. 12 . 
         FIG. 14  is a top, front and left side perspective view of a third embodiment of an offset outlet flush valve that is constructed in accordance with the present invention. 
         FIG. 15  is a left side elevational view of the offset flush valve shown in  FIG. 14 . 
         FIG. 16  is a top, front and left side perspective view of a fourth embodiment of an offset outlet flush valve that is constructed in accordance with the present invention. 
         FIG. 17  is a left side elevational view of the offset flush valve shown in  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings in detail, wherein like-numbered elements refer to like elements throughout,  FIGS. 1 through 5  illustrate a conventional flush valve, generally identified  10 , of a type that is known in the art. The flush valve  10  includes a valve body  12  that has a generally cylindrical central aperture  20  with a round valve seat  22  upon which a liftable flapper valve  50  can be supported, the flapper valve  50  being rotatable about opposing hooks  38 . The valve body  12  is secured within a drain hole  4  located in the bottom wall  6  of the toilet tank. The valve body  12  is supported by a flange  14 . A seal member  18  is interposed between the flange  14  and the toilet tank wall  6 . Typically, a large nut  16  (shown in phantom view in  FIGS. 3 and 4 ) is screwed over a male threaded lower outlet portion  40  of the cylindrical flush valve body  12 , on the underside of the bottom wall  6  of the tank. Extending upwardly from and to one side of the flush valve  12  itself is a cylindrical overflow tube socket  30  having an overflow tube  32  secured within the socket  30 . The purpose of the overflow tube  32  is to ensure that a proper water level is maintained within the toilet tank. Ideally, the inlet of the overflow tube  32  is set at a point where it is slightly above normal water level, but below the bottom of the flush lever nut that is located on a vertical wall of the tank for actuation of the flushing cycle. The overflow tube  32  is a vertically-extending circularly-tubular structure having a generally vertical axis  31  and a central aperture  34 , the axis  31  and the aperture  34  also forming part of the socket  30 . The central aperture  20  of the flush valve  12  itself is similarly a vertically-disposed circular structure having a generally vertical axis  41  and also having a greater inner diameter as compared to the diameter of the overflow tube  32 . In the typical configuration, a flow passageway  33  is defined at the bottommost portion of the overflow tube socket  30  whereby a water flow continuum is created between the overflow tube  32 , the socket  30 , the central passageway  33  and the outlet  40  of the flush valve  10 . That is, water flowing into the overflow tube  32  from the tank flows down the overflow tube  32 , then flows out of the tube socket  30  at the passageway  33  that is typically disposed at a right angle from the overflow tube  32 , into the central aperture  20  of the flush valve body  12 , and then flows through the flush valve outlet  40 . In this configuration, the bulb  54  of the flapper valve  50  can severely restrict the overflow capacity of the flush valve  10  by impinging on the flow area around the bulb  54 , including the much smaller passageway  19  that is located directed between the bulb  54  and the wall of the flush valve outlet  40  at the downstream end of the passageway  33 . See especially  FIG. 5 . This becomes particularly critical when an original equipment manufacturer (OEM) flapper is later replaced with a new flapper, typically manufactured by another company, which is made to some rather arbitrary specifications. Adequate overflow capacity is then overlooked and, if the passageway  19  between the overflow tube socket  30  and the flush valve outlet  40  is blocked, even in part, by the flapper valve bulb  54 , then the ability of the overflow tube  32  to do its job is compromised. The flush valve  10  of prior art is also rather difficult to mold as a one-piece item using conventional plastic molding processes as described earlier. 
     Referring now to  FIGS. 6 through 11 , they illustrate a first preferred embodiment of the flush valve, generally identified  110 , of the present invention as it would be installed within a hole  104  in the bottom wall  106  of a toilet tank. The valve  110  includes a valve body  112  having an inlet  120 , an outlet  140  and an overflow tube socket  130 . See  FIG. 8 . The valve body  112  includes a circumferential flange  114 , the flange  114  being reinforced by a plurality of upwardly extending ribs  119  disposed along the top side of the flange  114 . A seal member  118  is positioned below the flange  114  which provides a watertight seal between the valve body  112  and the bottom wall  106  of the tank. A generally cylindrical nut  116  is internally threaded and rotatable about the outlet  140  of the valve body  112 , the outer surface  142  of the outlet  140  also being threaded with cooperating threads. The outlet  140  further includes a generally cylindrical outlet aperture  144 , the outlet aperture  144  being defined generally by an outlet sidewall  146 . The outlet aperture  144  also has a generally vertical axis  141 . See  FIG. 11 . 
     The flush valve body  112  also includes an inlet  120 . The inlet  120  includes an inlet, or flapper valve, seat  122 . Note that the inlet seat  122  is slightly inclined from horizontal and the edge portion of the valve body  112  defining the inlet seat  122  is rounded. See  FIGS. 8 ,  10  and  11 . In this way, the inlet seat  122  is configured to allow the peripheral lip  152  of a flapper valve  150  to sealingly rest upon the inlet seat  122 . The bulb  154  of the flapper valve  150  sits within an inlet aperture  124 , the inlet aperture  124  being defined generally by an inlet sidewall  126 . The inlet aperture  124  also includes an axis  121  which is tipped away from vertical. The inlet aperture  124  intersects the outlet aperture  144  of the valve body  112  to form a water flow continuum therebetween. That is, when the flapper valve  150  is pulled upwardly and away from the inlet seat  122 , water contained within the tank will flow through the inlet aperture  124  and then through the outlet aperture  144  to the toilet bowl during normal flushing of the toilet. 
     The flush valve body  112  of the present invention further includes an overflow tube socket  130 . The overflow tube socket  130  includes a socket aperture  134  that is defined by a socket sidewall  136 . The socket aperture  134  has a generally vertical axis  131 . The overflow tube socket  130  is functionally adapted to receive a first overflow tube section  132  and an extensible second overflow tube section  133 . A compression ring  135  is provided which allows the position of the second overflow tube section  133  to be changed relative to the first overflow tube section  132 , the first overflow tube section  132  being fixed in its position relative to the overflow tube socket  130  of the flush valve body  112 . In this preferred embodiment, the tube sections  132 ,  133  are generally cylindrical tubes having slightly different diameters such that the second tube section  133  is slidably received within the first tube section  132  with a small clearance between those sections. The second tube section  133  also includes a flared inlet  136  to increase flow capacity of the overflow tube sections  132 ,  133  during overflow conditions within the tank. The socket aperture  134  also intersects a portion of the outlet aperture  144  of the valve body  112  to form a water flow continuum therebetween. That is, when water contained within the tank rises to a level that exceeds the fixed height of the tube sections  132 ,  133 , water flows into the overflow tube sections  132 ,  133 , through the socket aperture  134  and then through the outlet aperture  144 . This placement of the outlet  144  relative to the socket aperture  134  greatly increases flow during overflow condition since the bulb  154  of the flapper valve  150  does not create a barrier to effective water flow through the valve  112  as it does in the valve of the prior art. See the phantom view of the flapper valve  150  and the flapper valve bulb  154  as shown in  FIG. 11 . 
     Although this first embodiment of the offset outlet flush valve  110  could be used with a toilet tank of original manufacture, the height-adjustability feature of the overflow tube sections  132 ,  133  make this a more attractive choice for after-market applications. A pair of hooks  138  are disposed to either side of the overflow tube socket  130 . The purpose of the hooks  138  is to provide the anchoring means for the flapper valve  150 , including a replacement flapper valve  150 , and about which the flapper valve  150  rotates. 
     Preferably, the various parts of the offset outlet flush valve  110  are injection molded using a suitable plastic such as ABS plastic or glass filled polypropylene. However, none of the above materials are considered a limitation of the invention. A wide variety of other suitable, durable and low cost materials for injection molding are also available. 
     Referring now to  FIGS. 12 and 13 , they illustrate a second preferred embodiment of the offset outlet flush valve, generally identified  210 , of the present invention. In this alternative embodiment, the flush valve  210  has a valve body  212  that is intended for OEM applications. As shown, the valve body  212  includes an offset outlet  240  which functions in much the same way as that of the first preferred embodiment described above. That is, the outlet  240  is “offset” from the inlet  220  and repositioned to be placed under a portion of the socket  230 . This placement of the outlet  240  relative to the socket  230  greatly increases flow during overflow condition since the bulb (not shown) of a flapper valve (shown in phantom view) does not create a barrier to effective water flow through the valve body  212  as it does in the valve of the prior art. The major difference with this embodiment is that the overflow tube  232  is formed as part of the socket  230  and its height is manufactured in accordance with a pre-determined dimension. Also significantly different is the fact that the uppermost portion  237  of the overflow tube  232  is flared to impart even greater flow capacity in an overflow condition. The inlet  220  of the valve body  212  also includes a rim  222  upon which the flapper valve (shown in phantom view) may rest. 
     Referring now to  FIGS. 14 and 15 , they illustrate a third preferred embodiment of the offset outlet flush valve, generally identified  310 , of the present invention. In this alternative embodiment, the flush valve  310  has a valve body  312  that is also intended for OEM applications. As shown, the valve body  312  includes an offset outlet  340  which functions in much the same way as that of the embodiments described above. The outlet  340  is “offset” from the inlet  320 . In this embodiment, the overflow tube  332  is also formed as part of the socket  330  and its height is manufactured in accordance with a pre-determined dimension. Also significantly different is the shape of the tube  332 , which is generally rectangular in transverse cross-section, and the fact that the bottommost portion  339  of the overflow tube  332  is ramped to impart even greater flow capacity to the flush valve  310  in an overflow condition. This placement of the outlet  340  relative to the socket  330  greatly increases flow during overflow condition since the bulb (not shown) of a flapper valve (shown in phantom view) does not create a barrier to effective water flow through the valve body  312  as it does in the valve of the prior art. The uppermost portion  337  of the overflow tube  332  is flared to further improve flow capacity during overflow conditions. The inlet  320  of the valve body  312  also includes a rim  322  upon which the flapper valve (shown in phantom view) may rest. 
     Referring now to  FIGS. 16 and 17 , they illustrate a fourth preferred embodiment of the offset outlet flush valve, generally identified  410 , of the present invention. In this alternative embodiment, the flush valve  410  has a valve body  412  that is similarly intended for OEM applications. As shown, the valve body  412  includes an offset outlet  440  which also functions in much the same way as that of each of the other preferred embodiments described above. The overflow tube  432  of this embodiment is again formed as part of the socket  430  and its height is manufactured in accordance with a pre-determined dimension. Also different is the fact that the uppermost portion  437  of the overflow tube  432  is flared to impart even greater flow capacity in an overflow condition. The placement of the outlet  440  more closely to the socket  430  greatly increases flow during overflow condition since the bulb (not shown) of a flapper valve (shown in phantom view) does not create a barrier to effective water flow through the valve body  412  as it does in the valve of the prior art. The inlet  420  of the valve body  412  also includes a rim  422  upon which the flapper valve (shown in phantom view) may rest. Another difference with this embodiment is the fact that the rim  422  has a “flattened” portion  424  at its point closest to the socket  430  and overflow tube  432 . While this embodiment would require the use of a particularly formed flapper valve as compared to the other embodiments described above, the flush valve  410  of this embodiment is more compact in is front-to-back dimension, thus taking up less space in the toilet tank (also not shown). 
     The present invention also provides a method for making the offset outlet flush valve bodies  112 ,  212 ,  312 ,  412  of the present invention. Each of the flush valves  110 ,  210 ,  310 ,  410  described above eliminates the requirement of molding the lateral section of the passageway through the valve body separately, as was required to be done with valve bodies of the prior art, thus simplifying the mold process, reducing costs, and increasing the durability of the goods. In some processes, complicated retracting mold cores would also be used. All of these disadvantages are avoided by offsetting the outlets  140 ,  240 ,  340 ,  440  of the flush valves  110 ,  210 ,  310 ,  410 , respectively, and in particular, the axis  141 , in the flush valve  110  of the first preferred embodiment, such that the retracting mold for the bottom of the valve body and the retracting mold for the overflow tube meet, or nearly meet, thus eliminating the need for an extra horizontal, or lateral, connection, or retracting mold. In the first preferred embodiment, the axis  141  of the outlet aperture  144  is located closer to the axis  131  of the overflow aperture  134  and the axis  121  of the inlet aperture  124  is tipped away from the vertical, as shown in  FIG. 11 . 
     Although the foregoing has been described with a certain degree of particularity, it is to be understood that the present disclosure has been made by way of example only and that numerous changes in the construction and the arrangement of components, some of which have been alluded to, may be resorted to without departing from the spirit and scope of the invention as it is described. 
     From the foregoing detailed description of the illustrative embodiment of the invention set forth herein, it will be apparent that there has been provided a new, useful and uncomplicated toilet flush valve having an offset outlet and a method for making the offset outlet flush valve.

Summary:
An offset outlet flush valve has a valve body, the valve body having an inlet comprising an inlet aperture, an overflow tube socket comprising an overflow tube aperture, and an outlet comprising an outlet aperture. The outlet aperture of the valve body, and the wall that defines it, intersects a portion of the inlet aperture and a portion of the overflow tube aperture and the walls that define them. In this way, a water flow continuum is created between the inlet aperture and the outlet aperture and between the overflow tube aperture and the outlet aperture. A number of alternative embodiments of an overflow tube socket and overflow tube are also provided depending upon OEM or after-market application of the offset outlet flush valve.