AN IMPROVED CNG (COMPRESSED NATURAL GAS) FILLER VALVE
FIELD OF INVENTION
This invention relates to a Filling device made of a aluminium alloy, used to fill
CNG to tanks / CNG cylinders, used for transportation, storage or operation of
CNG for automotive and non automotive application.
BACKGROUND ART
Because of environmental concerns and emissions laws and regulations,
manufacturers of motor vehicles are searching for a clean burning and cost
efficient fuel to use as an alternative to gasoline. Natural gas is one candidate
for such a purpose, and many vehicles have been converted to natural gas as a
fuel source.
CNG is considered as a relatively clean source of energy that helps to avoid the
global warming, and is expected to be more widely used as automotive fuel in
place of more conventional gasoline. However, gas has a lower density than
liquid or solid, and is required to be highly compressed to be stored in a limited
space available in a motor vehicle or the like. Steel is a typical material for
manufacturing a pressure vessel for CNG.
To overcome this problem, there have been proposals to manufacture a filler
valve using composite material and thereby reduce the weight of the pressure
vessel which works. A valve is fitted just below the mating surface to prevent
the tank from leaking.
The filler valves helps to supply of compressed natural gas (CNG) to the
cylinders fitted in a vehicle and is exposed to large variations in environmental
conditions. For example, wide variations in temperatures and pressures may be
encountered. During filling operations, instantaneous temperature drops of at
least 50 exceed ambient by 20 variations in temperature, as well as the rapid
increases in pressure during filling, may result in the nominal working pressure
in a gas cylinder varying from several hundred up to several thousand pounds
per square inch (psi). Thus, the refuelling valve must be able to handle high gas
pressures up to 4,500 psi without leakage or failure.
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Currently, filler valves are designed with a receptacle adapted to mate with a
fuelling nozzle and have a check valve positioned within the receptacle. The
design prevents any leaking liquid or vapour fuel which increases considerably
the risk of a vehicle fire or explosion. Such designs, however, may be difficult to
service or replace. Accordingly, the need exists in this art for a refuelling valve
which provides for easy and safe refuelling and yet is convenient to service or
replace.
SUMMARY OF INVENTION
In view of such problems of the prior art, a primary object of the present
invention is to provide a filling valve provided with a Aluminium alloy grade
material which can withstand 1000 bar pressure and an improved sealing
arrangement that can maintain the required sealing performance under all
pressure conditions.
A second object of the present invention is to provide a filling valve provided
with improved sealing arrangement that can be assembled easily and in a
reliable manner.
A third object of the present invention is to provide a Soft Poly Urethane washer
provided on back side of O-ring for smooth movement of O-ring during knob
rotation & helps as a secondary seal for double safety.
A fourth object of the present invention is to provide a 1.0 Pitch of M14 thread
for wider opening for gas path with less Rotation of knob, hence better gas flow
& faster filing of tank.
A fifth object of the present invention is to provide two O-rings for better safety.
In case first O-ring gets damage, second will stop the leakage. O-ring sealing is
provided for double safety.
A sixth object of the present invention is to provide an unique design of metal
to metal seal with help of a crush ring on body face & probe guide face along
with metal to metal seal.
In an embodiment the resilient seal member i.e. the PU ring is interposed
between the tubular member and valve which free from deformation when the
interior of the filling valve is placed under various pressure conditions so that
the sealing performance of the resilient seal member can be ensured under all
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pressure conditions. Typically, both the valve and tubular member are made of
metallic material.
BREIF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 illustrates the filler valve in accordance with the present invention;
Fig. 2 illustrates a side view, partially in section, of fitment of soft PU washer in
accordance with the present invention;
Fig. 3 illustrates a side view, partially in section, of the assembly of 1.0 Pitch of
M14 thread in accordance with the present invention;
Fig. 4 illustrates a side view, partially in section, of the fitment of Two O- ring in
accordance with the present invention;
Fig. 5 (a) and (b) illustrates a side view, partially in section, of the assembly of
unique design of metal to metal seal with help of a crush ring in accordance
with the present invention.
DETAILED DESCRIPTION
Referring now to Fig. 1, which illustrates a filler valve adapted for working with
one or more pressurized vessels or cylinders mounted internally within the
vessel. Each cylinder is designed to be able to withstand nominal working
pressures of up to 220 bar, and the valve also is designed to be able to handle
those pressures without leakage. The valve is designed, as explained in greater
detail below, so that the pressure of the fuel from the filling supply automatically
opens the valve.
The filler valve is shown in Fig. 1 and includes a valve body which has a gas
flow passage which extends through the valve body from a first end which
communicates with the interior of valve to a second end which communicates
with outlet ports. The valve body includes external threads which permits the
valve to be screwed onto a suitable mounting.
The valve body substantially has a rectangular shape with a stepped outer
circumferential surface. Herein, the valve body is shown in Fig. 1. The
discharging flow path is formed inside the valve body to discharge CNG by
communication between the filling chamber and the outside. Further, for
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opening/closing the passage on the discharging flow path, a Guide Pin for
reciprocal movement of the valve body along the axial direction is used. This
Guide Pin is inserted first in the Knob ring with help of M14 X 1.0 threads and
Knob ring is further assembled in valve body with help of M22 X 1.0 threads.
Knob ring remains stationary inside valve body and only Guide pin rotates to
open or close the gas passage going towards CNG tank.
The insertion portion is inserted in the first hollow portion of the first cylindrical
portion and the hollow portion of the second cylindrical portion. In an
embodiment and as shown in Fig. 3, a 1.0 pitch of M14 thread provided wider
opening for gas path with less rotation of knob, hence better gas flow & faster
filing of tank.
The base portion has a cylindrical shape with a diameter larger than that of the
insertion portion. On the filling chamber side of the outer circumferential surface
of the base portion, an external thread portion is formed. The external thread
portion is screw-engaged with the internal thread portion of the above
described first cylindrical portion.
A resilient O-ring as shown in Fig. 2 provides for sealing between valve body
and pressurized vessel. The O-ring has an annular shape and is formed from
an elastic material such as rubber. The O-ring is arranged between the
mouthpiece portion (the first cylindrical portion) and the insertion portion and is
housed in the housing groove. The O-ring is compressed in the radial direction
by the first bottom surface of the housing groove and the outer circumferential
surface of the insertion portion, and thereby deformed. Thus, the sealing
function of the O-ring satisfactorily works, and CNG is prevented from leaking
outside.
In gas flow passage is non-return valve. Also positioned in gas flow passage is
a return spring, which has vulcanized one O-ring, into a sealing relationship
with probe guide.
Two O-rings are provided for better safety. In case first O-ring gets damaged,
second will stop the leakage. The first ring and the second ring are rings that
restrict the movement of the O-ring along the axial direction in order to prevent
the O-ring from digging into the extremely small gap between the mouthpiece
portion and the insertion portion. The first ring and the second ring are formed
from rubber material such as a NBR or HNBR or the like, and the backup rings
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accordingly do not deform even when the pressure in the filling chamber varies
and an alternate pressure acts. Neither the first ring nor the second ring is cut
in the circumferential direction, and the both backup rings are endless.
The first ring and the second ring are housed in the housing groove. In detail,
the first ring is disposed in the inner side (on the one side, namely the left side
in Fig. 1), with respect to the axial direction, of the O-ring, while the second ring
is disposed on the outer side (the other side, namely the right side in Fig. 1),
with respect to the axial direction, of the O-ring. That is, along the axial
direction, the O-ring is sandwiched by the first ring and the second backup ring.
Thus, even when the pressure in the filling chamber rises by filling CNG the
pressure of CNG drops by discharging CNG, and thereby the O-ring moves to
the left or right in Fig. 2, in other words, an alternate pressure acts on the Oring,
the movement of the O-ring is restricted by the first ring or the second
ring. Accordingly, the O-ring is prevented from digging into the above-described
gap, and the outer circumferential surface of the O-ring is prevented from being
damaged.
Further, as described above, the first ring and the second ring are endless, and
neither has a cut portion in the circumferential direction. Thus, even when the
pressure in the filling chamber varies and an alternate pressure acts on the Oring,
it does not occur that the O-ring digs into a cut portion, and the outer
circumferential surface of the O-ring is prevented from being damaged.
The filler valve body according to the present invention includes: a filling
chamber structure having a filling chamber body, made by a special aluminium
grade with a filling chamber for filling CNG in the filling chamber and a valve
body, made by a special aluminium grade formed in a rectangular shape
integrally with the filling chamber body; a probe guide and a cap filler valve
having an insertion portion with a cylindrical outer shape inserted in the valve
body; an O-ring provided between the cylindrical body and the insertion portion
to seal any kind of leakage; and a first backup ring that is endless and disposed
on one side, with respect to an axial direction, of the O-ring to restrict
movement of the O-ring along the axial direction, wherein an annular housing
groove is formed on an inner circumferential surface of the cylindrical body
such as to be recessed outward with respect to a radial direction in order to
house the O-ring and the first backup ring, wherein the internal cylindrical body
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is provided with a first cylindrical portion integral with the filling chamber body
and a second cylindrical portion that is attachable/detachable along the axial
direction to/from the first cylindrical portion, and wherein the housing groove is
divided along the axial direction to face outward when the second cylindrical
portion detaches from the first cylindrical portion. The disclosed CNG filler valve
is designed to use for automotive application for filling the CNG from CNG
dispenser to CNG tank of vehicle. This product is designed to handle high
pressure and high stresses during filling and operation. Filling section of valve
i.e. the probe guide has two parts coupled together with help of threads and
sealed by O-ring. Since O-ring is always under high pressure and stress, may
fail over a period of time in the field. Since this valve is a safety item and any
leakage from valve may affect human life. To overcome this situation, an
unique design of metal to metal acts as a primary seal and O-ring acts as a
secondary seal. To get the metal to metal seal, one ring is machined on Body
which is crushed after tightening with the mating part at specified torque. This
ring also creates a permanent deformation on mating part and gives a perfect
seal between two parts.
The valve body is made of metal, such as a special grade Aluminum alloy used
against the conventional brass material used in other design. This reduces the
weight of valve but meets all safety parameters to meet ISO/ECE-R 110
standards. The valve main body has substantially rectangular outer shape and
includes a filling chamber body that is in a shell shape having a filling chamber
therein and a cap filler valve portion (a cylindrical body) in a cylindrical shape
formed integrally with the filling valve body at one end portion of the valve body.
The present invention meets that need by providing a filler valve assembly
which provides for rapid, efficient, and secured filling of compressed natural gas
powered vehicles. The filler valve assembly also permits depressurization of
the vehicle fuel system prior to servicing and maintenance thereof. The filler
valve assembly includes a receptacle adapted to mate with a fuel supply nozzle
and a valve body having first and second gas flow passages there through. The
respective first ends of the first and second gas flow passages communicate
with the receptacle, while the respective second ends of the first and second
gas flow passages are adapted to communicate with a fuel storage vessel,
typically through a fuel supply line.
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In use the valve is positioned in the first gas flow passage of the valve body
and is normally biased into a closed position to prevent the flow of gas through
the first gas flow passage. The valve opens in response to a flow of fuel under
pressure, permitting the flow of gas to the fuel storage vessel or vessels.
As shown in Fig. 5 (a) and (b), filling CNG valve of the present invention
includes a receptacle and a valve body. Both receptacle and valve body are
preferably manufactured of suitable corrosion-resistant metal as discussed
above. The receptacle preferably has an exterior profile which will mate with
standard CNG fuel nozzles. Receptacle is connected to valve body via a
threaded adapter fitting which includes external threads on both ends thereof
which mate with corresponding internal threads on the receptacle and valve
body. A jam nut secures the assembly to an exterior surface of a vehicle wall so
that valve body is interior of the vehicle wall while receptacle extends outwardly
from the wall for easy access for filling.
The, receptacle includes therein an annular gas flow passage. Gas flow
passage includes a first end which terminates at the exterior surface of the
receptacle. The opposite (second) end of gas flow passage communicates
through a passage in outlet fitting with one or more fuel storage tanks (not
shown). The passage has a diameter which is smaller than the diameter of the
remainder of gas flow passage which forces the pressure drop in the flow of
gaseous fuel into the fuel storage tank(s) to occur downstream of the valve
assembly. This feature also aids in preventing icing of the check valve
assembly.
The filler valve includes a probe guide and a shaft extending there from. The
shaft is slidably mounted within probe guide. The probe guide itself is adapted
to slide within the gas flow passage. It is normally biased by a spring which
urges probe head into a sealing relationship with O-ring. A probe stop which is
threaded into one end of valve body acts to secure the spring, probe guide, and
plug in position within gas flow passage. Probe stop includes at least one orifice
therein through which gas flows.
As shown in the fig. 5 (a) and (b), also positioned within valve body is a cap
filler valve or by-pass valve, which blocks a second gas flow passage. Second
gas flow passage extends through valve body and communicates with gas flow
passage and provides an alternate gas flow path for the gaseous fuel around
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the filler valve. By-pass valve includes an internally threaded stem, a washer, a
sealing ring, and a knob ring. An O-ring and backup ring together act to seal
valve stem and nut. As is conventional, backup ring is manufactured of a higher
hardness rubber to prevent the softer O-ring from extruding through the gap
between the valve stem and nut. By-pass valve is normally sealed against
valve seat in second gas flow passage.
Although the foregoing description of the present invention has been shown and
described with reference to particular embodiments and applications thereof, it
has been presented for purposes of illustration and description and is not
intended to be exhaustive or to limit the invention to the particular embodiments
and applications disclosed. It will be apparent to those having ordinary skill in the
art that a number of changes, modifications, variations, or alterations to the
invention as described herein may be made, none of which depart from the spirit
or scope of the present invention. The particular embodiments and applications
were chosen and described to provide the best illustration of the principles of the
invention and its practical application to thereby enable one of ordinary skill in the
art to utilize the invention in various embodiments and with various modifications
as are suited to the particular use contemplated. All such changes, modifications,
variations, and alterations should therefore be seen as being within the scope of
the present invention as determined by the appended claims when interpreted in
accordance with the breadth to which they are fairly, legally, and equitably
entitled.

CLAIMS:-
1. A CNG filler valve assembly comprising:
a receptacle adapted to mate with a fuel supply nozzle;
a filling chamber structure having a filling chamber body with a filling chamber
for filling CNG in the filling chamber and a valve body formed in a rectangular
shape integrally with the filling chamber body;
a probe guide and a cap filler valve having an insertion portion with a cylindrical
outer shape inserted in the valve body;
an O-ring provided between the cylindrical body and the insertion portion to
seal any kind of leakage and a first backup ring that is endless and disposed on
one side, with respect to an axial direction, of the O-ring to restrict movement of
the O-ring along the axial direction;
wherein an annular housing groove is formed on an inner circumferential
surface of the cylindrical body such as to be recessed outward with respect to a
radial direction in order to house the O-ring and the first backup ring;
wherein the internal cylindrical body is provided with a first cylindrical portion
integral with the filling chamber body and a second cylindrical portion that is
attachable/detachable along the axial direction to/from the first cylindrical
portion, and
wherein the housing groove is divided along the axial direction to face outward
when the second cylindrical portion detaches from the first cylindrical portion.
2. A CNG filler valve assembly as claimed in claim 1, wherein the valve body
has substantially rectangular outer shape and includes a filling chamber body
that is in a shell shape having a filling chamber therein and a cap filler valve
portion having a cylindrical shape formed integrally with the filling valve body at
one end portion of the valve body.
3. A CNG filler valve assembly as claimed in claim 1, wherein a soft Poly
Urethane washer provided on back side of O-ring for smooth movement of Oring
during knob rotation and acts as a secondary seal for double safety.
4. A CNG filler valve assembly as claimed in claim 1, wherein the cap filler
valve further comprises of a Guide Pin for reciprocal movement of the valve
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body along the axial direction for opening/closing the passage on the
discharging flow path.
5. A CNG filler valve assembly as claimed in claim 4, wherein, the Guide Pin
is inserted first in the Knob ring with help of M14 X 1.0 threads and Knob ring is
further assembled in Valve body with help of M22 X 1.0 threads.
6. A CNG filler valve assembly as claimed in claim 5, wherein the Knob ring
remains stationary inside valve body and only Guide pin rotates to open or
close the gas passage going towards CNG tank.
7. A CNG filler valve assembly as claimed in claim 1, further comprises of a
metal to metal seal with help of a crush ring on body face & probe guide face
along with metal to metal seal.
8. A CNG filler valve assembly as claimed in claim 1, further comprises a
resilient seal member made of poly urethane material is interposed between the
tubular member and valve which free from deformation when the interior of the
filling valve is placed under various pressure conditions so that the sealing
performance of the resilient seal member can be ensured under all pressure
conditions.
9. A CNG filler valve assembly as claimed in claim 7, wherein the valve
and tubular member are made of metallic material.
10. A CNG filler valve assembly as claimed in claim 1, wherein the valve
body is made of a special grade Aluminum alloy which reduces the weight of
valve and meets all safety parameters to meet ISO/ECE-R 110 standards.
Dated: this 09th day of July, 2014