Flush valve structure for a toilet tank

Abstract

A toilet tank flush valve structure, for use with a toilet tank having a floor formed with an opening, includes a base for installation in the opening formed in the floor of the toilet tank. The base defines a water outflow passage having an upper end at which the passage has an area A 1 and a lower end at which the passage has an area A 2 and includes a valve seat at the upper end of the water outflow passage. A flush valve is movable relative to the base between a sealing position in which the valve engages the valve seat in sealing relationship and a flushing position in which the valve is spaced upwardly from the valve seat. The area A 1 is substantially greater than the area A 2.

1 . A toilet tank flush valve structure, for use with a toilet tank having a floor formed with an opening, the flush valve structure comprising:
 a base for installation in the opening formed in the floor of the toilet tank, the base defining a water outflow passage having an upper end at which the passage has an area A 1  and a lower end at which the passage has an area A 2  and including a valve seat at the upper end of the water outflow passage, and   a flush valve that is movable relative to the base between a sealing position in which the valve engages the valve seat in sealing relationship and a flushing position in which the valve is spaced upwardly from the valve seat,   and wherein the area A 1  is substantially greater than the area A 2 .   
   
   
       2 . A flush valve structure according to  claim 1 , wherein the opening bounded by the valve seat is circular and the opening bounded by the lower end of the base is circular and the opening having the area A 1  has a diameter that is at least 1.3 times the opening having the area A 2 . 
   
   
       3 . A flush valve structure according to  claim 2 , wherein the opening having the area A 1  has a diameter at least 1.5 times the diameter of the opening having the area A 2 . 
   
   
       4 . A flush valve structure according to  claim 1 , wherein the area of the water outflow passages decreases smoothly from the upper end to the lower end. 
   
   
       5 . A flush valve structure according to  claim 1 , wherein the flush valve is a column valve that moves relative to the base by vertical displacement of the flush valve. 
   
   
       6 . A flush valve structure according to  claim 1 , wherein the flush valve is a flapper valve that moves pivotally relative to the base about a horizontal axis. 
   
   
       7 . A flush valve structure according to  claim 5 , wherein the flush valve is a dual volume flush valve assembly. 
   
   
       8 . A flush valve structure according to  claim 7 , wherein the base includes a frusto-conical extension that flares upwardly and the flush valve includes an upper outflow tube that extends downward into the frusto-conical extension. 
   
   
       9 . A flush valve structure according to  claim 8 , wherein the upper outflow tube defines an interior passage that decreases in cross-sectional area in a downward direction. 
   
   
       10 . A flush valve structure according to  claim 1 , wherein the flush valve is a single volume flush valve. 
   
   
       11 . A flush valve structure according to  claim 1 , wherein the base includes an offset structure for positioning the upper end of the water outflow passage horizontally offset from the opening formed in the floor of the toilet tank. 
   
   
       12 . A flush valve structure according to  claim 11 , wherein the offset structure is an S-shaped tube. 
   
   
       13 . A flush valve structure according to  claim 11 , wherein the offset structure is a skewed frusto-conical extension that flares upwardly. 
   
   
       14 . A toilet tank structure comprising:
 a toilet tank having a floor formed with an opening,   a flush valve base for installation in the opening in the floor of the toilet tank, the floor of the toilet tank being also formed with a valve seat that surrounds the flush valve base and defines an inlet end of a water outflow passage, the inlet end of the water outflow passage having an area A 1  and the base having an outlet opening of area A 2 , and   a flush valve that is movable relative to the base between a sealing position in which the valve engages the valve seat in sealing relationship and a flushing position in which the valve is spaced upwardly from the valve seat,   and wherein the area A 1  is substantially greater than the area A 2 .