Patent Application
20150128337
Embodiments of the present disclosure relate generally to a seal configuration for use in connection with vacuum systems. The seal configuration finds particular use in vacuum waste flush systems, but may be used in any other types of vacuum systems. The seal configuration also finds particular use in passenger transport vehicles that have on-board lavatories with vacuum toilet systems. The seal configuration generally provides an offset configuration, which can result in a larger seal on the vacuum side. This can slightly delay the opening of the waste side seal with respect to the vacuum side seal of the system, proving an improved vacuum environment. This can also give the flow of waste a more direct transition across a vacuum plate as it flows through a flush valve.
Aircraft and other passenger transport vehicles typically have on-board lavatories with vacuum toilet systems. These systems typically include a waste-receiving toilet bowl connected to a main waste tank via a sewer pipe or main waste line. A discharge or flush valve is typically mounted on the sewer pipe to selectively allow fluid communication between the toilet bowl and the main waste tank. To power the toilet system, the waste reservoir is maintained under a pressure that is substantially lower than the pressure in the waste-receiving toilet bowl, which is typically under the near-atmospheric pressure of the aircraft's passenger cabin. Thus, when the discharge/flush valve is opened, the pressure differential between the bowl and the reservoir causes the waste in the bowl to be drawn through the pipe into the waste reservoir. (A pressure differential may also be generated via a vacuum generator, for example, if an aircraft is on-ground or if the system is used on a land or water-based vehicle.)
Discharge valves typically have a cylindrical housing with an inner chamber sized to contain a disk-shaped plate with an opening therein. One side of the housing has an inlet that is generally aligned with an outlet that is located on the opposite side of the housing. The waste-receiving toilet bowl is connected to the inlet by one portion of a sewer pipe, and the main waste tank is connected to the outlet of the valve housing via another portion of the sewer pipe.
A drive mechanism selectively rotates the disk-shaped plate between an open position and a closed position. In the open position, the opening in the disk-shaped plate is aligned between the inlet and the outlet, which allows fluid communication for the flushing of the vacuum toilet. In the closed position, the opening in the plate is moved away from the inlet and outlet area, such that it blocks fluid communication between the inlet and the outlet, preventing fluid from flowing between the bowl and the reservoir.
In vacuum waste systems, differential pressure is what drives the collected waste from the toilet bowl into the accumulation point (which is typically the main waste tank). The discharge valve should provide an interface for such a vacuum system without venting the pressure differential completely. It should also allow for the controlled addition of material into the ambient-pressure environment, while providing a leak-free obstruction that can be moved or rotated in a controlled manner so as to allow for the passage of a mixed media bolus from the ambient-pressure environment (e.g., the toilet bowl) to the low pressure environment (e.g., the waste tank). The discharge valve is then returned to its closed position in order to prevent further movement of waste into the waste tank until the next flush is activated. One example of a valve for use with a vacuum toilet is shown and described by co-owned U.S. Pat. No. 6,325,356.
While many discharge or flush valves are available that achieve these tasks, a number of problems have arisen associated with their reliability due to the deleterious nature of human waste on mechanical devices. For example, due to the high degree of differential pressure being controlled by the flush valve, waste may be ingested into the interior of the valve housing during the flush process, which contributes to corrosion of internal components. Additionally, ingested waste may dry and harden, preventing the actuation of the flush valve and significantly reducing the reliability of the valve. It is thus desirable to provide improved flush valves and seal configurations.
Embodiments described herein thus provide a seal configuration with a generally offset configuration. This can result in a larger seal on the vacuum side. The configuration can slightly delay the opening of the waste side seal with respect to the vacuum side seal of the system, proving an improved vacuum environment. The configuration can also give the flow of waste a more direct transition across a vacuum plate as it flows through a flush valve.
In one example, there is provided a seal configuration for use in a vacuum flush system, comprising: a housing having a fluid inlet, a fluid outlet, and a conduit therebetween; a flush plate dividing the conduit into a vacuum-side and a waste-receptacle side, the flush plate having an opening for selectively allowing fluid passage through the opening; a vacuum-side seal on the vacuum-side of the flush plate, a waste-receptacle side seal on the waste-receptacle side of the flush plate, wherein the vacuum-side seal is offset from the waste-receptacle side seal.
Embodiments of the present invention provide an improved seal configuration 10 for use with a flush valve system 12. The flush valve system 12 may be used in connection with a vacuum toilet, but other flush valves may also implement the improves seal configuration described herein. Although the seal configuration 10 is described for use with a toilet system, and specifically for use with a vacuum toilet for use on-board a passenger vehicle such as an aircraft, it should be understood that this seal system may be used with any other system that seeks to use a valve across a pressure differential situation and/or a valve that can transport waste or any other form of media. Examples of alternate uses include but are not limited to facility-based vacuum waste systems, facility-based vacuum transport systems, mixed media processes in oil and gas industries, conditional overboard venting in aerospace applications, or any other appropriate instance when a flush valve is needed.
As shown in
The perspective views of the housing 16 shown in
The cross-sectional views of
As shown in
In a specific embodiment, the vacuum side seal 34 may be a larger seal than the waste side seal 32, such that when the seals 32, 34 are positioned against the flush plate 14, the vacuum side seal 34 is offset from the waste side seal 32 along at least one location.
One advantage is that by providing a larger vacuum side seal 34, the waste flow “W” can be prevented from getting caught along any vacuum side 30 seal edges. As shown in
Another advantage of the described seal configuration 10 is that it causes the vacuum side 30 to be exposed to vacuum before the waste receptacle side 28 is exposed to vacuum. As shown in
The movement of the flush plate 14 is controlled by driving action of an actuator/motor, which is transferred by a gear assembly. The actuator/motor is controlled by a position sensing mechanism, which allows the flush plate 14 to move. The flush plate 14 can be moved to block the interface 26 between the inlet 18 and the outlet 20 (i.e., when it is moved to a nonalignment positioned with the inlet and the outlet), preventing any transfer of vacuum or transfer of waste from an ambient-pressure environment on the inlet side to a low pressure environment on the outlet side.
Continued movement of the flush plate 14 as shown in
Continued movement of the flush plate 14 causes the opening 24 to align with the conduit 50 as shown in
As described, because the vacuum side seal 34 breaks first and venting is allowed, by the time the flush plate opening 24 moves to allow the waste receptacle side seal 32 to break, there is a smaller change in pressure. This results in less pressure that may otherwise attempt to pull waste flow into the housing, rather than causing its movement through the housing. The lowered pressure change between the waste receptacle side 28 and the vacuum side 30 can minimize the occurrence of a high pressure that can pull waste into the housing. This is in contrast to systems that provide concentric seals that open at the same time.
With the prior art concentric seals, the seals are opened at the same time. As soon as the seals are opened, the vacuum pressure inside the housing experiences an abrupt drop, which can pull waste into the housing. Providing offset seals that expose the vacuum side to vacuum first (and consequently, by slightly delaying when the waste side is exposed to vacuum) allows a 2-stage pressure difference. The pressure differential between the two sides can be staged, rather than applying pressure equally and simultaneously. This lowered pressure difference allows time for the housing to vent. The pressure in the housing cavity can be lowered. By the time that the waste is introduced, there is less pressure influence on the waste to be pulled into the housing cavity. The internal pressure of the housing can be more equalized, and instead of some particles of waste being pulled into crevices of the housing , the waste flow is encouraged to move more smoothly and directly across the flush plate 14.
Although the figures show the seals 32, 34 against the flush plate 14 as having a generally circular circumference, it should be understood that other shapes and configurations are possible. For example, the seals may be oval shaped, kidney shaped, oblong, triangular, or any other appropriate shape or configuration.
Additionally, although the seals are shown as I-beam seals in cross-sectional view, it should be understood that any other type of seal may be used instead. For example, the seals may be o-ring seals, trapezoidal seals, square seals, or any other seals that are appropriate for use with a vacuum system. The seals may be inserted into grooves of the flush plate or they may lie flush against a flush plate surface.
The seals may be made of any appropriate material as well. For example, they may be elastomeric, plastic, nylon, a flouropolymer, or any other materials. The seals may also be coated with various greases, oils or talcums, or other lubricants.
Changes and modifications, additions and deletions may be made to the structures and methods recited above and shown in the drawings without departing from the scope or spirit of the invention and the following claims.
This application claims the benefit of U.S. Provisional Application Ser. No. 61/902,906, filed Nov. 12, 2013, titled “Offset Seal Concept,” the entire contents of which are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61902906 | Nov 2013 | US |
