Fluid handling – Liquid level responsive or maintaining systems – By float controlled valve
Reexamination Certificate
2000-02-24
2001-01-30
Walton, George L. (Department: 3753)
Fluid handling
Liquid level responsive or maintaining systems
By float controlled valve
C137S442000, C137S446000, C137S614200, C141S018000, C141S095000, C141S198000, C141S213000
Reexamination Certificate
active
06178994
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tap for compressed or liquefied gases, and more particularly to a tap for compressed or liquefied gases which has an overcharging prevention function, in which a two-way valve permits high speed charging a gas through an opening opened at initial state until a gas storage tank is fully filled with the liquefied gas, regardless of pressure/level of the liquefied gas inside/outside a gas storage tank, and the tap, for higher charging efficiency in the gas storage tank, has a buffering disk permitting that a level-controlling valve does not interfere with operations of a cam and a float during the charging of the gas and that an abrupt drop of the level-controlling valve is prevented at the full-filling level, so that slow blocking of the gas supply is conducted.
2. Description of the Conventional Art
Apparatuses which use gas, such as liquefied petroleum gas (LPG), liquefied natural gas (LNG), compressed natural gas (CNG), etc., need to be recharged at a gas dispensing station when a gas storage tank of the apparatus is empty.
To prevent explosion possibly occurring due to the overcharging of gas when gas is recharged in the gas storage tank, it is required to provide a safety valve which, in the case of charging the gas with a certain level of a gas pressure, automatically operates by the gas pressure in the gas storage tank and is then operated to externally discharge the overcharged gas.
For a proper operation of the safety valve, the filling level of the liquefied gas to be filled in the gas storage tank has to be retained at a certain level so that a gaseous zone can be formed at the upper side.
A prior art relating to the tap for compressed or liquefied gases has been disclosed in U.S. Pat. No. 5,282,496 issued on Feb. 1, 1994, entitled “Tap for Compressed or Liquefied”. Referring to
FIG. 1
, the tap for compressed or liquefied gases disclosed in the above-mentioned U.S. Pat. No. 5,282,496 will be described below.
As shown in
FIG. 1
, the tap for compressed or liquefied gases disclosed in the above-mentioned U.S. Pat. No. 5,282,496 comprises: an upper body
10
having an inlet channel
18
communicating with the inside of the body
10
, the inlet channel providing a passage for flowing a gas introduced from the external, and having an outer lower part thereof provided with a screw thread
12
enabling the tap to be screwed onto a gas storage tank; an open/closure valve
14
and a packing
16
enabling manual open/closure of the inlet channel
18
; and a safety valve
26
which enables the gases to externally escape through a passage
24
in the event of abnormal overpressure of the gas inside the gas storage tank.
Further, the tap for compressed or liquefied gases comprises: a lower body
32
coupled to the inside of the gas storage tank, having a lower side thereof provided with a two-way valve
30
having a chamber
38
inside, and a central portion whose both sides form the openings
34
,
36
; a piston
40
which slides in the chamber
38
by the pressure of the gas infused from the inlet channel
18
, while maintaining the sealing by the seal
46
and the gasket
42
, and having inside a passage
48
for introducing some portions of the infused gas; a spring
44
installed at a lower portion of the piston
40
, for offering a restoration force allowing the piston
40
to return to its original position; an orifice
50
formed on a side surface of the lower body
32
, operated to permit the remaining gas in the chamber
38
to flow to the gas storage tank; a level-controlling valve
52
movable up and down between the opened position defined by a washer
55
and the closure positions defined by the seal
54
; a cam
56
rotatably supported by the arms
58
, and for driving the level-controlling valve
52
; a float
62
for driving the cam
56
by a descent/ascent motion depending upon the varying pressure (level) in the gas storage tank; and a two-way valve
30
installed between the passage
48
and the chamber
38
, having a pendulum
64
serving to stop the gas supply through the channel
66
formed inside, when the tank is tilted.
A description will now be given of the operation of the conventional tap for compressed or liquefied gases as described above.
With the connector
22
being connected to a gas source outside the gas storage tank, a user opens the open/closure valve
14
, so that the pressurized gas penetrates through the inlet channel
18
. The pressurized gas pushes downward the piston
40
against the action of the spring
44
, and the gas is infused into the gas storage tank through the openings
34
,
36
. Also, some portion of the gas penetrates through the passage
48
of the piston
40
to the lower part of the chamber
38
and flows around the level-controlling valve
52
, in the compulsorily open position by the cam
56
, into the gas storage tank.
As the tank fills up, the float
62
rises, thus resulting in a counter-clockwise pivoting of the cam
56
. When the cam
56
pivots in a counter-clockwise direction, the top of the cam
56
brings into contact with a lower end of the valve
52
, followed by the cam
56
starting to present a hollow part
56
a
to the level-controlling valve
52
and then a descent of the valve
52
through the effect of the pressure of the filling gas.
As a result, the level-controlling valve
52
comes into contact with the seal
54
, which permits the stop of the gas supply into the gas storage tank through the level-controlling valve
52
. The stop of the gas supply into the tank induces the increase in pressure inside the chamber
38
formed between the piston
40
and the level-controlling valve
52
, and thus the piston
40
moves upward by the restoration force of the spring
44
.
Consequently, the closure of the openings
34
,
36
by the piston
40
stops the gas supply into the tank, which thus prevents the overcharging of the gas in order to maintain the preset level of the charged gas.
Meanwhile, the pendulum
64
serves to stop the gas supply through the channel
66
formed inside, when the tank is tilted.
However, since the above known tap for compressed or liquefied gases utilizes the scheme that the openings
34
,
36
are opened when the pressure of the infused gas pushes downward the piston
40
supported against the spring
44
in order to infuse the gas, it needs to maintain the pressure above a certain level of the pressure. This causes a problem in that the size of the opening closely relating to the pressure of the gas is confined below a certain size.
In the case of the opening
34
,
36
larger than a certain size, the reduction in the pressure of the gas by an amount corresponding to the increase in size of the opening presents, which induces partial closure of the opening caused by the rise of the piston
40
due to the restoration force of the spring
44
. This results in the reduction in size of the opening. Therefore, there is a problem in that the charging speed is limited depending upon the size of the opening which is defined by the pressure of the gas and the restoration force of the spring.
Further, under non-loaded condition of the conventional tap for compressed or liquefied gases, the piston closes the inlet channel
18
by the action of the spring. At this time, when the handle is rotated to open the packing
16
in order to use the stored gas, only a single gas flow path for externally discharging the gas exists which path leads to the inner passage in the piston
48
through the passage between the nut
51
and the level-controlling valve
52
.
In this case, since the diameter of the inner passage
48
is about 1.18 mm, maximum heat quantity permitted to be externally discharged is about 125,000 BTU/Hour, which quantity is considerably small. This means that a gas discharging quantity per time unit is small.
With such a retarded discharging/charging structure, a problem is caused in that a long time of about 12 minutes is taken to purge the empty gas storage tank, wherein the purging is
Rosenberg , Klein & Lee
Walton George L.
Young Do Industrial Co., Ltd.
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