Receptacles – High-pressure-gas tank – With removable closure
Reexamination Certificate
2000-02-15
2001-02-13
Moy, Joseph M. (Department: 3727)
Receptacles
High-pressure-gas tank
With removable closure
C220S586000, C220S304000, C220S502000, C220S901000
Reexamination Certificate
active
06186356
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to storage tanks having liners, especially storage tanks with plastic liners used for storing compressed gaseous fuels.
2. Description of the Related Art
Pressure vessels are widely used to store liquids and gases under pressure. One growing application of pressure vessels is their use in the storage of alternative fuels, such natural gas or propane, for use in vehicles such as automobiles. Natural gas and propane are increasingly viewed as preferable to gasoline for fueling vehicles. Accordingly, approaches have been devised for converting gasoline-fueled vehicles to natural gas-fueled or propane-fueled vehicles by retrofitting them to use natural gas or propane instead of gasoline. Additionally, new vehicles are currently being built which are designed to operate using natural gas or propane as the fuel source.
Vessels used for storing natural gases and propane preferably are equipped with a plastic liner, which serves to keep the stored gas from leaking. The plastic liner preferably covers the entire interior surface of the pressure vessel, including the neck portion, which defines an access opening for loading fuel. To prevent leakage of fuel at the access opening, an O-ring or other sealing means may be used.
An example of a sealing arrangement initially considered by the inventors is shown in FIG.
3
. As shown in
FIG. 3
, the sealing arrangement includes a plastic liner
300
covering the inner surface
302
of a pressure vessel
304
. A nipple portion
306
of the plastic liner
300
covers the inner periphery of the neck region
308
of a polar boss
310
. An O-ring
312
abuts against the edge (unnumbered) of the neck region
308
and is urged towards the neck region
308
as fitting body
314
is moved towards the neck region
308
to compress the O-ring
312
therebetween. The fitting body
314
and the polar boss
310
have respective complementary screw-threaded surface regions facing and engaging each other at
316
. Rotational movement of the fitting body
314
relative to the polar boss
310
mechanically engages the fitting body
314
to the pressure vessel
304
and seals the fitting body
314
against the nipple portion
306
of the plastic liner
300
, with the O-ring
312
interposed therebetween to establish a hermetic seal.
While the design illustrated in
FIG. 3
is acceptable under ideal operating conditions, under extreme temperature and pressure conditions, such as those sometimes encountered in harsh climates, the plastic liner
300
tends to contract, causing the liner
300
to move away from the fitting body
314
. Separation of the edge of the plastic liner
300
from the polar boss
308
interrupts the hermetic seal created by the O-ring
312
, causing fuel, especially in gaseous state, to leak from the pressure vessel
304
to the outside environment.
It would, therefore, be a significant advancement in the art to provide a simple sealing arrangement which, upon engagement of the fitting body to the storage vessel, forms a hermetic seal between the plastic liner and the end fitting that is resistant to high loading pressures and extreme operating temperatures, such as from about −40° C. 40° F.) to about 82.2° C. (180° F.).
SUMMARY OF THE INVENTION
It is, therefore, an object of this invention to address the problems outlined above and attain the above-mentioned advancement in the art by the provision of a pressurized-gas storage assembly with an improved closure assembly that prevents separation of the plastic liner from the polar boss of the pressure vessel.
In accordance with the principles of this invention, the above and other objects are accomplished by a pressurized-gas storage assembly including a pressure vessel, which comprises both an inner surface defining a gas storage chamber and a neck region defining an access opening in fluid communication with the gas storage chamber. A liner covers at least a portion, and preferably the entirety of the inner surface of the pressure vessel. A nipple portion of the liner extends into the neck region of the pressure vessel before terminating at an annular rim positioned within the neck region and facing away from the gas storage chamber. An annular O-ring is placed into the neck region of the pressure vessel to abut against the annular rim of the liner.
The assembly further includes an attachable fitting body for sealing and unsealing the access opening. The fitting body comprises a head portion terminating at one end at an annular shoulder, and an extension protruding from the head portion of the fitting body to define an inner circumference of the annular shoulder. When the fitting body is inserted into the neck region of the pressure vessel, the extension is received within and mechanically engaged with the nipple portion of the liner to prevent unintentional separation of the fitting body from the liner during use. As the fitting body is moved into mechanical engagement with the nipple portion of the liner, the annular shoulder of the fitting body simultaneously moves into close proximity to the annular rim of the liner, so that the O-ring resting on the annular rim is interposed between the annular shoulder and the annular rim and, depending upon the proximity of the annular rim to the annular shoulder, is compressed therebetween. The O-ring thereby establishes a hermetic seal between the liner and the fitting body, thus preventing escape of gas from the pressure vessel.
The inventive sealing assembly may be equipped in conventional tanks, including those having cylindrical configurations, as well as conformable tanks of the type described below. The assemblies may be installed in various types of vehicles, including, without limitation, automobiles, trucks, sports utility vehicles, military vehicles, and the like. In addition, the assemblies may be used for tanks, especially portable tanks, such as scuba tanks and oxygen tanks used by firefighters and the like.
Other objects, aspects and advantages of the invention will be apparent to those skilled in the art upon reading the specification and appended claims which, when read in conjunction with the accompanying drawings, explain the principles of this invention.
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Superior Valve Company advertisement, Electronic Cylinder Shut-off Valve, Natural Gas Fuels Magazine, May, 1995.
Parker O-ring Handbook.
Berkley George A.
Warner Mark J.
Cordant Technologies Inc.
Moy Joseph M.
Pillsbury Madison & Sutro LLP
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