Baths – closets – sinks – and spittoons – Flush closet – Bowl
Reexamination Certificate
2000-03-21
2001-07-10
Huson, Gregory L. (Department: 3754)
Baths, closets, sinks, and spittoons
Flush closet
Bowl
C222S133000, C417S440000, C004S224000, C137S565010
Reexamination Certificate
active
06256802
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to vacuum toilets, and more particularly to rinse fluid systems used in vacuum toilets.
BACKGROUND OF THE INVENTION
Vacuum toilets having rinse fluid systems are generally known in the art. Such vacuum toilets generally include a bowl having an outlet connected by a discharge pipe to a vacuum source, which generates a vacuum level in the discharge pipe. A discharge valve disposed between the toilet outlet and the discharge pipe controls when vacuum is present in the toilet bowl. When the valve is open, a pressure differential created by the vacuum at the bowl outlet and atmospheric pressure inside the toilet bowl pushes material present in the bowl into the discharge pipe.
It is common for such vacuum toilets to provide a rinse fluid system which rinses the surface of the bowl while the discharge valve is open. The rinse fluid systems typically include a spray ring which extends around the rim of the toilet bowl and is formed with nozzles. The nozzles are positioned so that the entire inside surface of the bowl is rinsed when the spray ring is connected to a source of rinse fluid. A problem associated with such rinse fluid systems is the build-up of deposits in the nozzles. Certain materials, such as calcium carbonate, are dissolved in the rinse water. When rinse water remains in the nozzle, it eventually evaporates, leaving a calcium carbonate residue in the toilet bowl and the nozzles. Consequently, the surface of the toilet bowl may become roughened thereby reducing the efficiency with which waste is removed during the flushing operation. In addition, the residue may clog the nozzles, thereby causing incomplete rinsing of the toilet bowl.
In many vacuum toilet system applications, very little rinse fluid is used with each flush, and a very large volume of air passes through the system during each flush. As a result, a hard plaque may build up on the internal surfaces of the discharge pipe and holding tank. While the plaque may be removed using acid, it may not be safe to do so in certain applications, such as vacuum toilets used on aircraft.
It is further known to introduce a chemical reagent into the rinse fluid of a conventional flush toilet for sanitizing the toilet bowl at each flush. This may be done by hanging a cake of water-soluble material in the toilet tank. However, to the best of applicants' knowledge, a similar technique has never been applied to vacuum toilet systems, due to the need for an electric pump to introduce the chemical reagent into the rinse fluid. The need for an additional electrical outlet is a particular disadvantage with respect to retrofit applications such as on aircraft. Further, the electric pump would require controls, which would also require modification of the flush control unit of the vacuum toilet.
Commonly owned U.S. Pat. No. 5,692,250 to Oldfelt et al. discloses a vacuum toilet system in which a chemical reagent is introduced into a rinse water supply during each flush. The system uses a pressure-actuated pump which operates in response to the presence of pressurized rinse fluid, thereby to inject chemical reagent into the stream of rinse of fluid. As a result, the puLnp does not require additional electrical outlets or control lines.
While this system generally addresses many of the problems outlined above, applicants have found this system difficult to implement. More specifically, applicants have found that the check valves used to introduce the chemical reagent into the rinse fluid stream are susceptible to collapse under the pressure of the rinse fluid, thereby rendering reagent injection difficult. In addition, the chemical injection pump is susceptible to losing its prime due to the collection to air bubbles both in a pump chamber and upstream of the check valves. As described in the '250 patent, the pump includes a dual-headed piston disposed inside a housing. When the piston moves in a first direction, it draws reagent into a small diameter portion of the housing. When the piston moves in a second direction, the reagent in the small diameter portion is ejected into the rinse fluid stream. Air bubbles entrapped in the reagent may be drawn toward the chemical pump during operation. The air bubbles may aggregate at irregular surfaces in the reagent supply pipe, such as at shoulders, ledges, and corners, to form an air pocket which causes hydraulic lock of the reagent. In addition, air bubbles passing through the first check valve may collect in the pump chamber to form another air pocket. The air pocket inside the pump chamber may be so large that it is not purged through the second check valve with a single stroke of the pump, thereby causing the pump to lose its prime.
SUMMARY OF THE INVENTION
In accordance with certain aspects of the present invention, an apparatus is provided for injecting a reagent from a reagent supply into a stream of pressurized rinse fluid from a rinse fluid supply. The apparatus comprises a main conduit having an inlet adapted for fluid communication with the rinse fluid supply and an outlet. A reagent conduit has an inlet adapted for fluid communication with the reagent supply and an outlet in fluid communication with a downstream point of the main conduit. A first valve is positioned in an upstream portion of the reagent conduit and a second valve is positioned in a downstream portion of the reagent conduit, the first and second valves defining a pump chamber portion of the reagent conduit therebetween. A pressure actuated pump is provided having an actuating end in fluid communication with the rinse fluid supply and a pumping end in fluid communication with the pump chamber portion. The pressure actuated pump is biased toward a first position in which the reagent is drawn through the first valve and into the pump chamber portion from the reagent supply, and is movable to a second position in response to an actuating force generated by the pressurized rinse fluid contacting the actuating end, in which the reagent in the pump chamber portion is discharged through the second valve and reagent conduit outlet. A pressure reducer is disposed in the main conduit upstream of the downstream point.
In accordance with additional aspects of the present invention, an integrated apparatus is provided for injecting reagent from a reagent supply into a pressurized stream of rinse fluid from a rinse fluid supply. The apparatus comprises a solid housing body with a main bore formed in the housing body, the main bore having an inlet adapted for fluid communication with the rinse fluid supply, and an outlet. A reagent bore is formed in the housing body and has an inlet adapted for fluid communication with the reagent supply and an outlet in fluid communication with a downstream point of the main bore. A first valve is positioned in an upstream portion of the reagent bore and a second valve positioned in a downstream portion of the reagent bore, the first and second valves defining a pump chamber portion of the reagent bore therebetween. A pump bore is formed in the housing body, the pump bore having a large bore section in fluid communication with an upstream point of the main bore and a small bore section in fluid communication with the pump chamber portion of the reagent bore. A unitary piston is disposed in the pump bore, the unitary piston having a large diameter piston head disposed in the large bore section and a small diameter piston head disposed in the small bore section. The unitary piston is biased toward the large bore section to draw reagent through the first valve and into the pump chamber portion of the reagent bore, the pressurized rinse fluid contacting the large diameter piston head to drive the unitary piston toward the small bore section, thereby pushing reagent through the second valve and reagent bore outlet. A pressure reducer is disposed in the main bore between the upstream and downstream points.
In accordance with still further aspects of the present invention, an apparatus is provided for injecting a reagent from a re
Deal David
Evac International Oy
Huson Gregory L.
Marshall O'Toole Gerstein Murray & Borun
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