US 3097768 A
Description (OCR text may contain errors)
July 16, 1963 A. e. TASCA 3,097,768
FLUID STORAGE VESSEL Filed Jan. 11. 1960 I INVENTOR.
ANGELO G. TASCA 36 BY United States This invention relates to improvements in a sealing device for a gas container, and refers more particularly to a pressure energized piston seal operating in a slidable closure associated with a gas holder.
In containers holding volatile fluids having high vapor pressures, it is desirable to have a sliding closure to allow for changes of pressure within the container caused by temperature variations. Usually, a conventional closure seal is not movable within the cylinder with volume changes or if the seal is slidable within the fluid container, the seal pressure is not increased with changes in fluid pressure and/ or temperature variation.
It is the object of this invention to provide a slidable closure having a seal which is self actuated by the fluid pressure acting within a container.
A further object is to allow an increase of applied force accompanying an increase in deformation in seal material and a corresponding increase in unit sealing pressure.
A further object is to provide a self sealing closure in a fluid container slidable with volume variation and having a self-contained sealing apparatus.
Briefly described, the sealing device comprises compressible sealing material arranged within a wedgeshaped groove of a piston skirt that is interconnected with a piston head and operating in a fluid container. A tension device urges the piston head and skirt together compressing the seal material While great-er sealing pressures may be attained by directing greater fluid pressure to the piston head. Pressure directed to the underside of the piston head releases sealing pressure and allows the sealing device to be slidable with the container.
The objects, advantages and features of the present invention will be more apparent from the accompanying drawing and following detailed description.
In the drawing:
FIG. 1 is a top plan view of the present invention; and
FIG. 2 is an elevation sectional view taken along line 2-2 in the direction of the arrows.
Referring to the detailed drawing, there is a gas cylinder tank of any suitable configuration receiving a piston assembly comprised of a piston head 11 and a piston skirt 12. The cup-shaped head 11 is slidable within the tank 10 and has walls 13 that abut the internal walls of the gas cylinder tank 10. Piston wall return flange 14 is bent inwardly toward the longitudinal axis of the head 11 and tank 10. The return flange is interconnected with the skirt groove 15 of the piston skirt 12 since the groove return flange 17 is bent outwardly away from the longitudinal axis of the skirt 12. The groove incline 17 forms a wedge shape to the groove into which the wedge-shaped seal 18 can conform and also ride up the incline when the head 11 and skirt 12 are forced together.
The return flanges 14 and 16 interconnect which prevents the piston assembly from separating and also support the seal 18.
Brackets 20 are fixedly attached to the interface of the piston head 11 and are generally longitudinally positioned parallel to the piston assembly longitudinal axis. In the present invention six brackets 20 are equally spaced about the piston head interface although any suitable number may be used. Torsion springs 22 are hooked between bracket apertures 23 and the skirt return flange apertures 24 to hold the piston head 11 and skirt 12 in engaged relationship.
atent Gas cylinder tank end 30 serves the dual function of enclosing the open end of the tank 10 and acting as a stop for the piston assembly at its outer limit. The tank end wall 3-1 fits within the tank and is welded at 32 around the periphery of the tank end '30 and the tank 10. Any configuration of the tank end 30 may be used and any suitable type of mechanical seal may be employed such as a bonding or welding process. Spout 33 and valve 34 are attached to the upper tank end and may be used for the introduction of fluid pressure to the interface of the piston assembly to lower the position of the piston and effect a resulting increase in pressure of the fluid within the tank. Conduit 35- and valve 36 are provided at the lower end of tank 10 for introducing and evacuating fluid to and from area A.
Under usual operating conditions as for example when the apparatus is used for the storage of fuel or oxidizer in a missile, area A is filled with the material to be stored, for example liquid oxygen, nitric acid, JP-4, alcohol, or the like through valve 36 and conduit 35 and valve 36 closed. Area B is then filled with a highly volatile liquid such as helium or nitrogen and valve 34 closed.
Through a drop in fluid pressure or a loss in volume of fluid in area A, under storage conditions the change of the position of the piston assembly may be effected by fluid pressure within area B or introduced through spout 33 and into area B which counteracts the force of tension springs 22 and reducing the gap C to the point where the return flanges 1'4 and 16 contact. This pressure removes the outward force on the seal 18, and allows the piston assembly to be slidable within the tank 10. An increase of pressure in area A causes the piston head 11 to move in relation to the skirt 12 creating a gap C between the return flanges 14 and 16. Return flange 14 compresses the seal 18 causing it to ride up the groove incline 17 and assume a sealing relationship with the tank interface. Changes in pressure in area A causes corresponding changes in the amount of sealing pressure applied to the seal of the tank. An increase in the volume or pressure in area A causes the piston assembly to move automatically to the extreme limit and contact the tank end 30;
Changes in ambient temperatures or changes in the at mospheric conditions in which the tank is operating under allows movement in the tank closure without outside maintenance.
When it is desired to evacuate area A, valve 36 is simply opened. The pressure of the liquified gas in area B will then pump the fluid out of area A. Those skilled in the art will readily appreciate the fact that a source of either hydraulic fluid or gas, such as a pump or compressor attached at valve 34, can be used to pressurize area A so as to move the piston and evacuate area B.
It will be apparent to anyone skilled in the art that the present invention may be modified without departing from the spirit thereof, and hence, it is not intended that the invention be limited to the precise details shown and described except as necessitated by the appended claims.
1. In a liquid storing and dispensing device the combination of a tank and a piston assembly, said piston assembly including an upper portion and a lower portion, a. seal interposed between said piston upper portion and said piston lower portion, said piston lower portion having a closed end capable of retaining fluid pressure, a first pressure area isolated below said piston assembly, a second pressure area isolated above said piston assembly, a resilient element tending to place said piston lower portion and said piston upper portion in a collapsed position and tending to put said seal in compression, and in sealing relation with said tank, whereby if the pressure in said first pressure area is reduced in pressure below the pressure of said second pressure area, the pressure in said sec- 0nd pressure area will tend to force said piston lower portion and said piston upper portion into an uncollapsed position and said seal withdrawn from sealing relation from said tank, whereby said piston assembly is slidable within said tank.
2. A sealing device comprising a collapsible piston slidably received within a cylinder, said piston having a cup-shaped head and an interconnected annulus-shaped upper portion, a resilient tension device secured to said piston cup-shaped head and annulus-shaped upper portion urging said piston head and said piston upper portion into engagement, a wedge-shaped compressible seal positioned between said interconnected piston upper portion and said piston head, said piston upper portion having a wedge-shaped groove formed at one end, a wedgeshaped seal received by said wedge-shaped groove formed in said piston upper portion, one end of the said piston head being positioned within said wedge-shaped groove and abutting against said wedge-shaped seal.
Reterences Cited in the file of this patent UNITED STATES PATENTS