Fire extinguishers – Mount – cabinet or guard – Movable relative to fire
Reexamination Certificate
1999-11-23
2001-02-27
Morris, Lesley D. (Department: 3752)
Fire extinguishers
Mount, cabinet or guard
Movable relative to fire
C239S171000, C244S136000, C254S050100, C251S324000
Reexamination Certificate
active
06192990
ABSTRACT:
FIELD OF THE INVENTION
The invention pertains to a mechanical valve, which may be used to regulate fluid flow, for example in aerial fire fighting equipment.
BACKGROUND
Helicopter carried dump-buckets are well known for use in fighting forest fires. These buckets, at their simplest, may comprise a rigid or flexible reservoir or body for holding a volume of water, a sling to suspend the reservoir from a helicopter, a valve, and an actuator which is controlled from inside the helicopter to operate the valve to release the water from the reservoir over the fire.
In many existing buckets, the valve may consist of a simple flapper valve located on a bottom interior surface of the reservoir and operated by a remotely controlled actuator, for example. A flapper valve typically includes a base plate having an outlet therein, a flat flapper member disposed over-top of the base plate so as to block the outlet, and a hinge connected between an edge of the flapper member and the base plate to hingeably connect the flapper member to the base plate permitting the flapper member to alternately block and expose the outlet. While such a valve is mechanically simple and robust, it may have significant shortcomings.
In fire-fighting buckets, it may be desirable to place the valve at the bottom of the reservoir so as to permit the reservoir to be completely drained therethrough. In this location, the force of the full head of water in the reservoir resists the hinging of the flapper member and thereby resists the opening of the flapper valve. The resistive force increases directly as the area of the flapper member. Therefore, if a flapper valve having a reasonably large flapper member is provided, such that the reservoir may be dumped reasonably quickly, a fairly powerful motor may be required to actuate the flapper, resulting in increased weight and power consumption. Furthermore, the operation of the valve may create turbulent flow, causing the water to disperse laterally as it is dumped. As previously stated, one edge of the flapper member may be hingeably connected to the base portion. Therefore, when the flapper valve is opened, water may be blocked by the hinged edge while being permitted to flow to the outlet past the remaining edges. This may create unbalanced flows and turbulence. This effect may be exacerbated if the valve is opened only part way so as to operate as a metering valve. In fire-fighting, lateral dispersal may be undesirable as the water may be more susceptible to evaporation before reaching the ground and also because some of the water may overshoot the desired target.
Lastly, a flapper valve may not be adequately controllable to rapidly shut off the flow of water to permit multiple dumps, for example. When the valve is open, hydrostatic forces acting on the flapper member may tend to keep the valve open, canceling some of the hydrodynamic forces caused by the outflow of water which may tend to close the valve. Furthermore, the turbulence caused by the valve, as previously described, may further cancel the hydrodynamic forces. Such cancellations may slow the closure of the valve, causing the operator to dump a larger volume water than necessary, possibly the entire bucket load, in a location regardless of whether or not the full volume of water is required at that location.
Some existing buckets may use a butterfly valve in place of the flapper valve. A butterfly valve typically includes a longitudinally extending axle having first and second coplanar plates extending laterally therefrom. The butterfly valve may be connected to a bottom portion of the bucket and located in an opening therein. When closed, the first plate may seal against an interior surface of the bucket while the second plate may seal against an exterior surface of the bucket. The valve may be opened by rotating the first and second plates about the axle and may be fully opened by rotating the plates to a position perpendicular to their closed position. While the butterfly valve is hydrodynamically balanced, it may tend to cause lateral dispersal when operated as a metering valve and may be difficult to seal as one plate may be located inside the bucket and the other plate may be located outside the bucket.
Furthermore, both butterfly valves and flapper valves may tend to provide relatively poor seals as they may use flat gaskets which may only resist fluid flow directed normally to a plane of the gasket and which may permit fluid leakage directed parallel the plane of the gasket.
SUMMARY OF THE INVENTION
In one aspect, the invention provides a valve having an outer assembly and an inner assembly in which the outer assembly is moveable between open and closed positions, and the outer assembly has a reduced surface area on those surfaces which are disposed normally to a direction of movement. The outer assembly is thereby adapted to be less affected by hydrostatic and hydrodynamic forces directed so as to oppose its movement.
In accordance with one aspect of the invention there is provided a valve which may be housed in a fluid reservoir. The valve may include an inner assembly having a spaced apart top plate and base plate, and a substantially open side portion. The valve may also include an outer assembly with solid side walls that are complementary to the inner assembly. The outer assembly may be movable with respect to the inner assembly between an open position and a closed position so that an upper portion of the solid side walls sealably cooperate with the top plate only when the outer assembly is in the closed position, and a lower portion of the solid side walls sealably cooperate with the base plate only when the outer assembly is in the closed position. In the open position, flow through the valve is permitted through the open side portion and the outlet of the inner assembly. In the closed position, flow through the valve is prevented by sealing engagement between the solid side walls of the outer assembly and the top plate and by sealing engagement between the solid side walls and the base plate of the inner assembly.
In one embodiment of the invention, the valve may be used in a fire fighting device which may be carried to the site of a forest fire by a helicopter. In this embodiment, an operator, located inside the helicopter may send a command to a control head, instructing the control head to open, or partially open, the valve, thereby releasing water from the reservoir onto the fire. In the open and partially opened positions, the valve may be hydrodynamically balanced such that the flow of water may be a coherent stream. Before the reservoir is emptied, the operator may also instruct the control head to close the valve, retaining water in the reservoir for use elsewhere, thus permitting partial dumps.
The following detailed disclosure and drawings disclose several embodiments of the invention, which is capable of expression in structures other than those particularly described and illustrated.
REFERENCES:
patent: 3485302 (1969-12-01), Thorpe
patent: 3598342 (1971-08-01), Hawkshaw
patent: 3661211 (1972-05-01), Powers
patent: 3710868 (1973-01-01), Chadwick
patent: 3828857 (1974-08-01), Mason
patent: 4022377 (1977-05-01), Wagner et al.
patent: 4240507 (1980-12-01), Hokkanen
patent: 5560429 (1996-10-01), Needham
patent: 5829809 (1998-11-01), Arney et al.
Christie Parker & Hale LLP
Donald Brian Arney
Morris Lesley D.
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