Baths – closets – sinks – and spittoons – Flush closet – Tank only
Reexamination Certificate
1999-07-26
2001-05-29
Huson, Gregory L. (Department: 3751)
Baths, closets, sinks, and spittoons
Flush closet
Tank only
C004S378000, C004S395000, C004S398000
Reexamination Certificate
active
06237164
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to toilets, and more specifically, to the design of tanks which are used to store a quantity of water used to flush effluent from the toilet bowl.
2. History of the Prior Art
In the Western world, the earliest plumbing systems were developed to dispose of human wastes. Nearly simultaneous development of sewage disposal systems occurred in several locations in the ancient world. The earthenware pipes, masonry sewers, and toilets installed in about 2,500 B.C. in Mesopotamian cities (now included in present day Iraq), are still in working order. In the Indus Valley in what is now Pakistan and western India, most dwellings had drains for waste disposal by about 2500 B.C. A palace built on the island of Crete about 2000 B.C. had primitive toilets and a drainage system with air shafts that served as vents. The Romans contributed to the development of modem plumbing systems by constructing distribution systems for potable water, using lead pipes and fixtures.
After the fall of the Roman Empire in 476 A.D., the quality of plumbing declined throughout the Western world. During the Middle Ages, people disposed of waste materials by throwing them into the street. Although a type of flush toilet was developed in the 1500's, it did not come into wide use because of the general lack of plumbing and sewer systems. During the 17
th
century, many cities throughout the world began to construct water and sewer systems. In 1778, Joseph Bramah, an English cabinet maker, patented an improved flush toilet. By 1800, toilets had become common in England. But most of them drained into cesspools, which often overflowed. Septic tanks were invented in the mid-1800's, and a modem sewer system began operating in London in the 1860's.
For nearly two hundred years following the patenting of Joseph Bramah's improved flush toilet, though thousands of U.S. patents were granted for improvements to the device, the functional design of the fixture changed very little. Aesthetic improvements to the device were a major focus of inventors. Some of the efforts aimed at improving the aesthetics of the humble fixture actually degraded its performance rather dramatically. For instance, in the mid-1970's, a low profile toilet was manufactured that had rather abysmal flush performance as a result of the low potential energy of the water stored within the supply tank.
Several decades ago, water conservation suddenly became the rage. The standard tank-type toilet, which used about five gallons of water per flush cycle came under attack. In order to reduce water consumption, it became common to place bricks at the bottom of the supply tank Flush performance was somewhat decreased as a result. Then, in 1992, the U.S. Congress passed a national standard for new toilets, limiting them to 1.6 gallons (approximately 6.76 liters) per flush cycle. In some foreign countries, such as Singapore, where potable water is scarce, new toilets will be limited to only 4.5 liters per flush cycle.
The key to improving flush performance and decreasing water consumption is tank pressure. Europeans have long known that flush performance can be dramatically improved by elevating the toilet's supply tank to ceiling level. However, in the U.S. at least, that design is ignored because installation is more time consuming and the aesthetics of the device are apparently unacceptable. Many new water-efficient toilets available in the U.S. incorporate a supply tank that is pressurized by the water main. Such toilets provide acceptable flush performance using only about 1 and ½ gallons, or slightly less than 6 liters, of water. These toilets suffer from three major disadvantages. Firstly, they are considerably more expensive than a conventional toilet with an unpressurized supply tank. Secondly, in areas where water pressure is low or is variable over a wide range, flush performance will be unacceptable at least some of the time. Thirdly, the tank flush valve is more complex and not easily repaired by untrained service personnel.
Unpressurized toilets using 6.76 liters of water per flush are also available in the U.S. The problem with these devices is that flush performance is generally marginal. Consequently, many consumers tamper with the fill and flush mechanisms so that the water released per flush cycle is increased. Often the amount exceeds 13.0 liters per flush cycle. Another remedy for poor flush performance is double or triple flushing of the system. Many replacement components are available for these water-efficient toilets. However, there is no guarantee that a repaired toilet will conform to the original specifications. Another problem with water-efficient unpressurized toilets is the flapper component of the tank flush valve. Chlorine tends to deteriorate the rubber from which they are made, resulting in a device which may leak more water than it uses for operation.
What is needed is a toilet having low cost in combination with high performance flush characteristics, low water consumption, ease of maintenance, and a high degree of tamper resistance.
SUMMARY OF THE INVENTION
A toilet supply tank assembly having high performance flush characteristics is designed to maximize water pressure over the flush valve and to minimize fluid turbulence within the tank during a flush cycle. The greater the water pressure and the less dissipation of potential energy through turbulence, the less the water required for each flush cycle. The tank includes a bottom interior surface which tapers downwardly from the outer edges thereof to a fluid escape opening. This means that the shortest distance from any point on the bottom interior surface to the fluid escape opening is downwardly inclined. The downwardly-tapered bottom panel reduces water turbulence as water flows from the tank to the fluid escape opening during a flush cycle.
In order to minimize turbulence attributable to the shape of the tank caused by water flow as the tank empties, the new tank may have a cylindrical wall continuous with the downwardly tapering bottom portion. The fluid escape opening is centrally positioned in the bottom portion of the tank. In order to further reduce turbulence created by water flow within the tank during a flush cycle, a flush valve plunger has a frusto-conical stopper portion and a cylindrical upper portion with no abrupt transitions. The frusto-conical shape of the stopper portion coupled with a lack of abrupt transitions facilitates water flow through the fluid escape opening, thereby increasing the velocity and, hence, the energy of the water as it escapes the tank and enters the toilet bowl. The flush valve plunger incorporates an overflow/bowl refill tube, which passes through the center of the plunger.
The new toilet tank may also include at least three vertical partitions intersecting a common axis which not only provide a cage in which the flush valve plunger can slide up and down, but also prevent the water from swirling and forming an energy robbing vortex Alternatively, the fluid escape opening incorporates a support structure which is attached to a central guide over which the valve plunger slides. The tank may incorporate vortex spoiling panels to increase fluid velocity through the fluid escape opening.
As an optional feature to further increase the energy of water released into the toilet bowl, the tank assembly may also incorporate a free-fall tube below the fluid escape opening.
REFERENCES:
patent: 3860972 (1975-01-01), Costello
patent: 4196482 (1980-04-01), Martinez Mendez
patent: 4272768 (1981-06-01), Rookard, Jr.
patent: 4696414 (1987-09-01), Huat
patent: 5363513 (1994-11-01), Blankenburg
patent: 5651471 (1997-07-01), Green
patent: 532375 A1 (1993-03-01), None
Barnett Brent D.
LaFontaine Daniel T.
LaFontaine Joseph A.
Huson Gregory L.
Nguyen Tuan
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