US3837377A

US3837377A - Temperature compensated charging system and process for natural gas and the like

Info

Publication number: US3837377A
Authority: US
Inventors: Jones R Mc
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-05-06
Filing date: 1972-10-10
Publication date: 1974-09-24
Anticipated expiration: 1991-09-24
Also published as: GB1335254A; US3719196A; FR2091237A5; US3807422A; DE2121328A1

Abstract

A valve controls communication between a source of pressurized gas and containers which are to be charged with the gas. The valve in turn, is controlled by the pressure of a gas in a reference vessel which is in thermal communication with the containers to be charged. This reference vessel contains a quantity of gas charged into it at a predetermined temperature and pressure. The valve is controlled by the pressure of the reference vessel and the container to be charged such that when a predetermined pressure differential between the two exists, the valve closes communication between the source of gas the the containers.

Description

United States Patent Me] ones TEMPERATURE COMPENSATED CHARGING SYSTEM AND PROCESS FOR NATURAL GAS AND THE LIKE Robert W. McJones, 529 Via Del Monte, Palos Verdes Estates, Calif. 90274 Filed: Oct. 10, 1972 Appl. No.: 295,976

Related US. Application Data Continuation-impart of Ser. No. 34,966, May 6, 1970, abandoned.

Inventor:

US. Cl 141/4, 137/12, 141/18, 236/92 R Int. Cl B65b 3/00 Field of Search 141/1-7, 18, 141/20, 21, 25, 37, 39, 46, 192, 198, 211,

214, 226, 197; 137/12, 111, 112, 493.6, 493.7, 493.8, 493.9, 505.2, 505.42, 505.26, 505.11, 505; 25 l/6l.1; 236/92 R, 93, 99

References Cited UNITED STATES PATENTS 10/1965 Replogle 141/18 3,232,485 2/1966 Wilson 141/18 Primary ExaminerH0ust0n S. Bell, Jr. Attorney, Agent, or Firm-Christie, Parker & Hale 57 ABSTRACT A valve controls communication between a source of pressurized gas and containers which are to be charged with the gas. The valve in turn, is controlled by the pressure of a gas in a reference vessel which is in thermal communication with the containers to be charged. This reference vessel contains a quantity of gas charged into it at a' predetermined temperature and pressure. The valve is controlled by the pressure of the reference vessel and the container to be charged such that when a predetermined pressure differential between the two exists, the valve closes communication between the source of gas the the containers.

13 Claims, 5 Drawing Figures r" 1 1 fia. a C r I f I Z0 J 500.?6'5

a g l fi e 1 M 40 L 1 i Z2 M y :D

TEMPERATURE COMPENSATED CHARGING SYSTEM AND PROCESS FOR NATURAL GAS AND THE LIKE CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a continuation-in-part application of US. application Ser. No. 34,966 filed May 6, 1970 now abandoned.

BACKGROUND OF THE INVENTION The present invention relates in general to the charging of gases into pressure vessels and, more in particular, to a charging system which effects a predetermined quantity of gas in the pressure vessels regardless of environmental temperature.

A great deal of attention is being directed to the lowering of pernicious emissions'from internal combustion engines. These emissions include unburned hydrocarbons, carbon monoxide and oxides of nitrogen, all of which contribute to air pollution or smog. It has been found that natural gas, which is primariy methane, is a highly satisfactory fuel for internal combustion engines in that it significantly lowers the amount of pernicious emissions from these engines.

One of the methods of storing natural gas for use as a fuel with internal combustion engines is in high pressure vessels, tanks or containers. These containers are filled with natural gas at relatively high pressure, the pressure diminishing as gas is burned in the operation of internal combustion engines.

The containers used for natural gas are pressure limited. As a consequence, the containers are typically equipped with safety devices in the form of burst discs which will relieve excess pressure by discharging natural gas until atmospheric pressure exits in the containers. Obviously, once a disc bursts, the charge of gas is lost.

Charging of containers with natural gas occurs at various temperatures ranging from below freezing to about 100 F. Natural gas is not a perfect gas and its pressure varies dramatically with temperature. Because of this, a container rated at, say, 2,265 p.s.i. at 70 F., and which is charged at a low temperature of, say, to 2,265 F. p.s.i., will be at an extremely high pressure of about 3,150 p.s.i. when the temperature of the container reaches 90 F. Depending on the rating of the container and the rating of its burst disc, the burst disc could rupture at this pressure to discharge the container. Conversely, a container charged to 2,265 p.s.i. at an ambient temperature of, say, 100 F. will not contain very much gas when compared with the quantity of gas it would safely contain if charged at 70 F. Clearly, in this latter instance, the capacity of the container is not being used to its fullest extent.

The problem of utilizing the maximum capacity of a container commensurate with safety is not unique to natural gas. Even with perfect gases and other real gases such as oxygen, nitrogen and air, similar but less dramatic pressure and capacity problems are encountered. Examples are skindiving tanks and oxygen tanks for heart patients.

There is a need, therefore, for a means for effecting a predetermined charge in a pressure container regardless of the temperature of the container during chargmg.

SUMMARY OF THE INVENTION The present invention envisions the use of a reference vessel containing a predetermined quantity of a gas of the type to be charged into one or more other vessels or containers from a high pressure source. The reference vessel is in thermal communication with a container to be charged and controls a valve between the container and the source of gas. This control is by the pressure of the gas in the reference vessel. The valve is also sensitive to the pressure in the container, such that when the pressure in the container reaches a predetermined value relative to the pressure of the gas within the reference vessel, the valve terminates communication between the source of gas and the contamer.

Inasmuch as the reference vessel is in thermal communication with a container to be charged and controls the valve between the source of gas and the container, the quantity of gas charged will be independent of am bient temperature. This is so because the pressure in the reference vessel mirrors container temperature. Thus, on a cold day the gas pressure in the reference vessel is relatively low and termination of communication between the charging source and the containers occurs with reference to this low pressure. But on a hot day communication between the charging source and the containers terminates at a point dependent on the relatively higher pressure existing in the reference vessel. In either event, the quantity of gas in the charged vessels will be the same.

A specific and preferred form of a valve of the present invention contemplates the use of a valve body or housing adapted to be mounted on a container to be filled with a gas. The valve body has a chamber which contains a valving element. The position of the valving element determines whether there will be communication between a source of gas and the interior of the container. The reference vessel is adapted to be disposed within the container. A predetermined quantity of gas having essentially the same pressure-temperature characteristics as the gas to be charged into the container is in the reference vessel. The reference vessel is disposed in the container in position to sense the temperature of the bulk of the quiescent gas in the container to avoid the temperature effects of gas expanding into the container. Stated in different words, the reference vessel is disposed in a position where gas entering the container does not affect the temperature of the gas in the reference vessel except as it affects the temperature of the bulk of the gas in the container. The reference vessel, which may be a sealed bellows or a cylinder and a piston, has an element which is positionally responsive to a pressure differential acting on it, the differential being between the pressure within the vessel and the pressure within the container. Means, such as a push rod, couples the positionally responsive element of the vessel and the valving element together, such that when a predetermined pressure differential determined by the pressure in the container and reference vessel pressure exists, the push rod allows the valving element to close the containers interior to the source of gas. The valving element will open independently of the push rods position when the pressure in the chamber lowers, as when a demand for the gas in the container exists.

An alternate form of the valve suitable for use in the present invention has a valve housing with a chamber. A valving element is disposed for movement in this chamber in response to pressure differentials across the element. The chamber is in pressure communication with the reference vessel, and is adapted for communication with a container to be filled and a filling source, with the valving element between that portion of the chamber in communication with the reference vessel and that portion of the chamber adapted for communication with a container. The valving element is positionally responsive to the pressure in the container and the pressure within the reference vessel, such that when the pressure in the reference vessel is higher than the pressure in the container being filled, the valving element establishes communication between the filling source and the container. But when the pressure within the container bears a predetermined relationship to the pressure in the reference vessel, the valving element terminates communication between the container and the filling source.

The present invention is ideally suited for use in a vehicle employing natural gas as a fuel. In this application, a bypass check valve may be used to permit the use of the vehicles fuel line as the refueling line from the filling source to the containers.

In terms of process, the present invention contemplates the sensing of the pressure of a given amount of reference gas which is in thermal communication with a container to be charged with a gas. The reference gas may be contained in a reference pressure vessel as in the apparatus of the present invention. The reference gas has at least substantially the same temperature and pressure characteristics as the gas to be charged into the container. Gas is charged into the container and the pressure in the container and that of the reference gas are sensed. When there is a predetermined pressure differential between the two gases, charging is terminated.

These and other features, aspects and advantages of the present invention will become more apparent from the following description, appended claims and drawings.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a schematic depiction of the temperature compensated charging system of the present invention as employed in a fuel system of an internal combustion system which utilizes a gaseous fuel such as natural gas;

FIG. 2 is an elevational view, mostly in hal section of a preferred form of the valve half the reference vessel of the present invention;

FIG. 3 is an elevational view, mostly in half section, of an alternate preferred form of the reference vessel of the present invention;

FIG. 4 is an elevational, half-sectional view of an alternate valve of the present invention; and

FIG. 5 is a plot of pressure versus temperature for natural gas and a perfect gas to illustrate the problems solved by the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1, the charging system of the present invention is illustrated in general by reference numeral 10. The system includes a reference pressure vessel 12. The reference pressure vessel is disposed in thermal communication with containers or

cylinders

13, 14 and 15 to be charged with gas. This may be done by disposing the reference vessel within one of the cylinders as illustrated in FIGS. 1 and 2, or adjacent to the cylinder, as shown in FIG. 4.

However, it is important that the reference pressure vessel being in thermal communication with the bulk of the gas in the cylinders for proper temperature compensation. This is necessary because the bulk of the gas will be at a higher temperature than ambient until it cools, because of its compression. In this connection, it is also necessary to avoid the effects of gas expanding into the cylinders because this expanding gas is not at the temperature of the bulk of the gas in the cylinders.

The reference pressure vessel contains a predetermined quantity of gas having the same pressuretemperature characteristics as the gas used in the cylinders; obviously the same gas for both satisfies this requirement. This quantity is determined by the pressure to which it is desired to charge the cylinders. Thus with natural gas many cylinders are rated at 2,265 p.s.i. at F. The quantity of gas in the reference pressure vessel, then, would correspond to that required to effect a pressure of 2,265 p.s.i. at 70 F.

The reference pressure vessel is in communication with a valve 16 of a valving system 18. This valve has a valving element indicated by the flow arrow in FIG. 1 and by reference numeral 20. A chamber of this valve is in communication with the reference pressure vessel through a line 22. A second chamber of the valve is in pressure communication with the valves outlet through a pilot line 24. The valves outlet is shown in FIG. 1 by line 26. This line leads to the cylinders to be charged.

A filling source 28 of natural gas is disposed in fluid circuit with valve 16 through

lines

30, 32 and 34. Line 34 corresponds to the inlet of valve 16. Line 32 is the fuel line for an internal combustion engine 36. A valve 38 is disposed in line 30 between source 28 and line 32. This valve is any of a well-known number of disconnect valves for selectively communicating the source with fuel line 32. The source may be a compressor or tanks containing natural gas under pressure.

A valve 40 is shown in FIG. 1 for charging reference pressure vessel 12. As such, valve 40 is in fluid circuit with line 22.

With brief reference to FIG. 5, it is seen that the pressure of a given quantity of contained natural gas varies dramatically with the temperature. Thus at a temperature of 20 F. (440 R) the pressure of natural gas is l,370 p.s.i., and at a higher temperature of 160 F. (620 R) the pressure is 3,130 p.s.i. As previously mentioned, many cylinders are design rated at 2,265 p.s.i. at 70 F. This means that the cylinders in normal usage are capable of withstanding higher pressures corresponding to higher temperatures. However, this tolerance is somewhat limited and, as a consequence, safety devices such as relief valves or burst discs are used to relieve the pressure in the cylinders when pressures reach, say, 3,450 p.s.i. As can be determined from FIG. 5, if

cylinders

13, 14 and 15 were charged to 2,265 p.s.i. on a day when ambient temperature were 20 F. (440 R), then on a day when ambient temperature reached F. 560 R) the pressure within the cylinders would have exceeded the relief or burst pressure of the safety devices for the cylinders. On the other hand, for a perfect gas under the same conditions, the resultant pressure would have been 2,735 p.s.i. Conversely, and again with reference to FIG. 5, if cylinders 13, 14 and were filled to a pressure of 2,265 p.s.i. on a day when the ambient temperature was 100 F. (560 R), the pressure within the cylinders would drop to 1,240 p.s.i. when the temperature dropped to 0 F. (460 R). What this latter instance means in real terms is not a safety hazard but the filling of the cylinders to less than their rated capacity and as a consequence the gas within the cylinders would be used up much faster than need be.

While the above examples are somewhat extreme, the conditions can be met in practice and they do illustrate the previous requirement of close attention to the pressure-temperature characteristics of a gas to be charged into a container at high pressures.

But with the use of the reference pressure vessel of the present invention, the quantity of gas within the cylinders is the same regardless of the ambient temperature during filling of the cylinders. This is so because valving element is responsive to the pressure within the reference pressure vessel and the pressure downstream of valve 16. When the downstream pressure of valve 16 slightly exceeds the pressure in the reference pressure vessel, the valving element will close communication between the filling source and the cylinders. This closing, then, is a function of the pressure in the reference pressure vessel. Inasmuch as the gas within the reference pressure vessel and the gas being charged into the cylinders is the same, the quantity of gas charged into the cylinders will always be the same regardless of the temperature at which they are filled.

In greater detail, FIG. 1 illustrates the system of the present invention as it would be used in the fuel system of an engine which uses natural gas as a fuel.

Cylinders

13, 14 and 15 are in thermal communication with each other by virtue of the fact that they are normally disposed together as, for example, in the trunk of a motor vehicle. The use of a single reference pressure vessel 12 in cylinder 13 is acceptable if the quantity of gas in each cylinder is the same as in each other cylinder. As previously discussed, each cylinder has a safety device. These safety valves are shown as relief valves and are indicated by

reference numerals

42, 44 and 46 for

cylinders

13, 14 and 15, respectively. While relief valves are suitable for many applications, burst discs are normally used in vehicular operations. The use of burst discs will be specifically described with reference to FIG. 2. Each valve is operative to open upon the occurrence of a predetermined pressure within its associated cylinder. Lines 48, 50 and 52 are disposed between

valves

42, 44 and 46 and

cylinders

13, 14 and 15, re-

spectively. These lines are in gas communication with a line 54 which emanates from and is in gas communication with line 26 from valve 16. Control valves 56,58 and 60 are disposed in lines 48, 50 and 52, respectively, to enable the removal or installation of selective cylinders without affecting the pressure in other of the cylinders.

It is convenient to use a part of the fuel line of the vehicle as the fill line for

cylinders

13, 14 and 15. This is so because the fill fitting of valve 38 is conveniently disposed in the engine compartment of the vehicle, while, as previously mentioned,

cylinders

13, 14 and 15 are usually in the trunk of a vehicle. To effect this convenience, it is preferred to employ a check valve 62 shown in parallel with valve 16 in FIG. 1. The check valve admits to gas flow from the cylinders through a branch line 64 in which the check valve is disposed, but prevents the bypassing of valve 16 when the cylinders are being charged.

To complete the description of FIG. 1, line 32 leads into a first stage regulator 66 which drops gas pressure to a predetermined value of, say, 55 p.s.i. A solenoid operated on-off valve 68 is disposed in series gas com munication with regulator 66. It is controlled by the ignition switch of the vehicle, or in the case of a dual fuel equipped vehicle, by an on-off switch. In any event, during operation of engine 36, solenoid valve 68 is energized to allow gas to flow through it. A final stage of regulation is effected by regulator 70. This regulator is in series gas circuit with solenoid valve 68 and has an outlet pressure of, say zero inches of water. Fuel line 32 leads to a fuel-air mixer 72 from regulator 70. In fuelair mixer 72, air is mixed with gas at a predetermined fuel-air ratio for consumption in engine 36.

FIG. 2 illustrates the preferred form of the valve and the pressure vessel of the present invention. The valve is indicated generally by reference numeral 74 and the reference pressure vessel is indicated generally by reference numeral 76. A cylinder or tank 78 receives valve 74 and the pressure vessel extends into the cylinder.

Valve 74 includes a housing 80 having a hollow interior or chamber 82. A passage 84 extends along the longitudinal axis of the valve for the passage of gas through the valve into the interior of cylinder 78. A nipple 86 is secured in the interior end of the valve as by a threaded connection 88. Nipple 86 in turn carries reference pressure vessel 76 as by a threaded connection 90. Valve housing 80 is secured to a neck 92 of cylinder 78 as by a threaded connection 94. A valving element 96 is disposed for longitudinal movement within chamber 82 of valve 74. A biasing spring 98 urges valving element 96 towards passage 84. A valve seat 100, annularly disposed about the mouth of passage 84, cooperates with an elastomeric disc 103 disposed with a recess 102 of valving element 96 to effect closure of passage 84 from chamber 82 when the valving element is in its closed position against the seat.

A line 104 extends through the wall of housing 80 for communication with chamber 82. For use in a vehicle fuel system, line 104 would act as both the charging or fill line and fuel line of the vehicle, as described previously. A T-fitting 106 is carried through nipple 108 by valve 74. Nipple 108 provides communication between the interior of the T-fitting and passage 84. The nipple is secured to the valve as by a threaded connection 110. A burst disc 112 caps one end of the T-fitting and acts as a safety device. The leg of the T-fitting indicated by reference numeral 114, is used to couple the valve and reference pressure vessel to other tanks or cylinders in a bank of tanks or cylinders.

A cap 116 threaded to housing 80 of valve 74 at 118 closes chamber 82 and provides purchase for biasing spring 98.

A follower element in the form of a push rod 120 extends coaxially with passage 84 in the passage for coupling valving element 96 to reference pressure vessel 76. To provide gas communication throughout passage 84 and nipple 86, push rod 120 has a pair of fluted guides 122, the flutes being indicated by reference nueludes a body 128 having a hollow interior 130. A pressure responsive bellows 132 is disposed within this hollow interior. The bellows is filled with a predetermined quantity of gas which, as previously described, is readily effected by filling the bellows under controlled temperature and pressure conditions. The bellows. of course, is sealed and is secured to a fitting 134 as by a spring clip 136. A charging valve 138 is disposed for charging the bellows and is also secured to fitting 134. A bearing element 140 is disposed on the top of bellows 132 for bearing against an end 142 of push rod 120.

Thus bearing element 140, being positionally responsive to a pressure differential between the gas in the container and the gas in bellows 132, may be viewed as a sensing means which is included, together with push rod 120, in a responsive means for maintaining valving element 96 open until there is a predetermined pressure differential between container gas and bellows gas.

It is important that the reference pressure vessel sense the temperature of the bulk of the gas in tank 78 in order that the temperature of the gas in the reference pressure vessel be the same as the temperature of the bulk of the gas. The bulk of the gas will be at a higher temperature than ambient because of compression. Gas entering the tank from valve 74 will typically not be at the temperature of the bulk of the gas. Usually the entering gas is colder than the bulk of the gas. Consequently, reference pressure vessel 76 should be well within tank 78, further than illustrated may be required. Furthermore, there should be no thermal impediment between the gas in bellows 132 and the bulk of the gas as would occur if ports 126 were not far enough into tank 78 or if body 128 were too thick or not of a good heat conductor.

FIG. 3 shows an alternate form of the preferred embodiment of the reference pressure vessel of the present invention. For purposes of clarity, the attendant valve is not shown, it being identical to the one described above with reference to FIG. 2. This embodiment of the vessel, indicated in general by reference numeral 143, has a body 144 which has a hollow interior 146. The reference pressure vessel again is carried as in the FIG. 2 embodiment at a threaded coupling 148 between it and a nipple 150. Nipple 150 is carried by a valve (not shown) which is identical to valve 74 in the same manner as nipple 86. A push rod 152, identical to push rod 120, extends into the interior of the reference pressure vessel to contact a piston 154 for the coupling of the vessel with the valving element of the valve which is identical to valve 74. The piston is longitudinally displaceable within hollow interior 146 in response to a pressure differential across the piston. Again a reference pressure vessel charging valve 156 is provided for filling a lower chamber 158 within hollow interior 146 with a gas under controlled conditions of temperature and pressure. Piston 154 has a pair of O rings 160 to provide a seal between lower chamber 158 and an upper chamber 161. As will subsequently become apparent, these O-rings act, because of friction between the wall of body 144 which defines hollow interior 146 and the O-rings, to make the pressure responsive piston bistable. Chamber 161 is in communication with the hollow interior of the tank or container which carries reference pressure vessel 143. Thus. piston 154 acts as a sensing element quite similarly to bearing element 140 of the bellows 132 and cooperates with its push rod in a similar fashion.

Again with reference to FIG. 2, the operation of the embodiment shown will be described. As previously mentioned, bellows 132 has a charge of a predetermined quantity of gas. The exterior of the bellows feels the pressure within cylinder 78 by virtue of communication between interior of pressure responsive vessel 76 and the interior of the cylinder through port 126, nipple 86 and flutes 124. When it is desired to charge the cylinder with a gas to a predetermined pressure, line 104 is coupled to a source of gas as described in the schematic depiction in FIG. 1. At the outset of charging, the pressure in bellows 132 will exceed the pressure in cylinder 78 and the bellows will be in the expanded position shown in FIG. 2. In this expanded position, bearing element acts on push rod 120 which in turn acts on valving element 96 to maintain communication between the interior of cylinder 78 and fill line 104 through passage 84. As the pressure increases within the cylinder, its effect will be to tend to collapse bellows 132 and thereby withdraw push rod 120 from valving element 96 to enable the valving element, under the influence of biasing spring 98, to close on seat 100 and terminate communication between the source of gas and the interior of cylinder 78. At a predetermined point, then, the combined effects of the pressure of gas in cylinder 78 and the force of biasing spring 98 will overcome the pressure within bellows 132 of pressure responsive vessel 76, and valving element 96 will close. At this point no further charging is possible inasmuch as the valving element is closed and is stable in its position because of the effects of spring 98 and charging pressure within chamber 82. When valving element 96 closes, gas charging of other cylinders in the bank of cylinders is also terminated because T-fitting 106 is out of gas circuit with fill line 104.

When a demand is made of the contents of cylinder 78, a lower pressure will exist in chamber 82 than that which existed at the time valving element 96 closed. As a consequence, valving element 96 will open notwithstanding the withdrawn push rod 120. In short, valving element 96 behaves as a simple check valve.

The embodiment illustrated in FIG. 3 operates similarly to the one described with reference to FIG. 2. The pressure within the cylinder is felt in chamber 161 by piston 154. The pressure of the controlled quantity of gas in chamber 158 opposes this pressure. When the pressure in chamber 161 together with the force of the biasing spring of the associated valve is sufficient to overcome the static friction force between O-rings and the wall bounding interior 146 and the pressure in chamber 158, piston 154 will move fairly far to enable the closing of the valving element of the associated valve, the movement of the piston a discrete distance occurring because of the lowering of the coefficient of friction of the O-rings on the wall occasioned by the O- rrngs movement.

With reference to FIG. 4, an alternate form valve and reference pressure vessel is illustrated. A reference pressure vessel 162 is shown in thermal communication with a cylinder 164 to be charged. The communication effected in FIG. 4 differs from that illustrated in FIGS. 1, 2 and 3 in that the reference vessel is either in contact with the cylinder to be charged or is at least in the same area as that cylinder. However, it is preferred to have the vessel inside the cylinder to mirror rapidly the effects of compression on temperature. The reference pressure vessel is in pressure communication with a chamber 166 of a valve 168 through a line 170. A fitting or valve 172 is disposed in line 170 for the charging of the reference pressure vesselwith the desired gas under controlled conditions of temperature and pressure to effect a given quantity of gas in the vessel.

Valve 168 has a housing 174 which defines a hollow interior 175 of which chamber 166 forms a part. Within this hollow interior is a valving element in the form of a longitudinally displaceable spool 176. Spool 176 is disposed for movement within hollow interior 175 in response to a pressure differential across it by virtue of gas pressures existing in chamber 166 and in a second chamber 178. A passage 180 receives a line 182 from a source of gas for the charging of cylinder 164. The line shown is severed only for the purposes of illustration. In any event, spool 176 has an annulus 184 and a diametrically disposed passage 186. The latter passage communicates with a longitudinal passage 188 within the spool. Passage 180 is disposed relative to annulus 184 to communicate the annulus, passage 186 and passage 188 with the filling source through fill line 182. Longitudinal passage 188 terminates at chamber 178 and is aligned with an outlet passage 190 which receives a line 192. Line 192 leads to cylinder 164 for the latters filling.

Spool 176 has annular grooves 194 which receive rings 196. These O-rings prevent gas from passing along the wall defining interior 175 and spool 176 between annulus 184 and chamber 178. Similarly, an annular groove 198 in spool 176 receives an O-ring 200 for preventing leakage between chamber 166 and annulus 184.

A check valve 202 operates in the same manner as valve 62 of valving system 18 shown in FIG. 1. Here it is shown to be a ball 204 biased by a spring 206 against a seat 208 to normally prevent communication between a line 210 and passage 190. When the pressure in passage 190 exceeds that in line 210 and the force of spring 206, ball 204 moves off seat 208 and gas can flow from passage 190 through the check valve and into line 210. Line 210 leads to line 182 which also serves as the fuel line for a vehicle.

The operation of the FIG. 4 embodiment is as follows. As previously mentioned, reference vessel 162 is charged with a predetermined quantity of gas. When cylinder 164 is to be charged, the pressure existing in the reference vessel will exist in chamber 166 to bias spool 176 to the position shown in FIG. 4. Gas from the filling source will pass through line 182, into annulus 184, through diametric passage 186, through longitudinal passage 188 and into passage 190 where it discharges through line 192 into cylinder 164. When the pressure in the cylinder exceeds the pressure in the reference vessel by a small amount, the force on spool 176, because of the pressure in chamber 178, will exceed that existing on the spool because of the pressure in chamber 166. As a consequence, the spool will move to the left in FIG. 4 to terminate communication from the filling source with annulus 184. At this point the cylinder has been charged with a predetermined quantity of gas and the filling source may be disconnected from line 182. As the gas in cylinder 164 is used, the

pressure of the reference vessel will soon bias the spool to the position shown in FIG. 4, that is, with annulus 184 in communication with passage 180. But before this happens gas can flow through check valve 202 and into line 182 for its consumption. After the pressure in the cylinder lowers sufficiently for spool 176 to find itself in the FIG. 4 position, gas can pass through check valve 202 as well as through longitudinal passage 188, diametric passage 186, annulus 184 and into line 182.

The present invention has been described with reference to certain preferred embodiments. The spirit and scope of the appended claims should not necessarily, however, be limited to the foregoing description.

What is claimed is:

1. A temperature compensated charging system comprising:

a. a constant volume container adapted to be charged with a gas from a high pressure source thereof;

b. a closed reference vessel within the container containing a predetermined quantity of a gas under pressure and being in thermal communication with the container such that the gas in the reference vessel is at least substantially at the temperature of the bulk of the gas in the container even when the container is being charged with a gas and the pressure of the gas in the reference vessel is a direct function of the temperature therein and, hence, the temperature of the gas in the container, the gas in the reference vessel having at least substantially the same temperature-pressure characteristics as the gas to be charged into the container;

c. means for sensing the pressure of the gas in the reference vessel;

d. means for sensing the pressure of the gas in the container;

e. valve means for selectively communicating the high pressure source of the gas to be charged into the container with the container; means responsive to both pressure sensing means to open the valve means and communicate the high pressure source with the interior of the container when there is less than a predetermined pressure differential between the gas in the interior of the container and exterior of the reference vessel on the one hand and interior of the reference vessel on the other and until there is the predetermined pressure differential at which time the responsive means closes the valve means to prevent communication between the container and the high pressure source of the gas; and

g. whereby, the amount of gas charged into the container is essentially independent of the temperature thereof and essentially dependent on the predetermined pressure differential.

2. The temperature compensated charging system claimed in claim 1 wherein:

a. the valve means includes a housing having a chamber, a first passage into the chamber for supplying gas from the high pressure source thereinto, a second passage into the chamber for discharging gas from the chamber into the container, and a valving element disposed in the chamber for movement therein between an open and a closed position to open and close the second passage to the chamber,

- respectively; and

b. the responsive means is coupled to the valving element and the reference vessel such that the valving element is maintained open until the predetermined value is reached.

3. The temperature compensated charging system claimed in claim 2 wherein:

the responsive means includes a push rod disposed between the valving element and the reference vessel; and

the reference pressure vessel has a pressure responsive element which is positionally responsive to the pressure within the container and the pressure within the reference vessel, the responsive element being coupled to the push rod and the push rod being coupled to the valving element to maintain the valving element in its open position until the predetermined value is reached.

4. The temperature compensated charging system claimed in claim 3 wherein:

a member is included which is carried by the valve means; and

the reference pressure vessel is carried by the memher.

5. The temperature compensated charging system claimed in claim 3 wherein the valve means includes biasing means for biasing the valving element into its closed position, the predetermined value being a function of the force of the biasing means, the pressure within the container and the pressure within the reference vessel.

6. The temperature compensated charging system claimed in claim 3 wherein the pressure responsive element includes a sealed bellows, the sealed bellows containing the predetermined quantity of gas.

7. The temperature compensated charging system claimed in claim 3 wherein the reference pressure vessel includes a housing having a hollow interior and the pressure responsive element includes a piston disposed for movement within the hollow interior of the housing and dividing such hollow interior into a first and a second chamber, the first chamber being adapted for pressure communication with the container and the second chamber containing the predetermined quantity of gas.

8. The temperature compensated charging system claimed in claim 3 wherein means are provided for effecting a discrete amount of movement of the pressure responsive element at the predetermined value.

9. For use in charging a predetermined quantity of a gas into a constant volume, pressurized container from a high pressure source of the gas regardless of temperature, a temperature compensated charging system comprising:

a. the container;

b. a valve mounted on the container and having means for communication with the source of high pressure gas, the valve having an open position for gas passage into and out of the container and a closed position for preventing gas passage into and out of the container;

c. a closed reference pressure vessel within the container, the reference pressure vessel containing a predetermined quantity of gas under pressure and d. means for sensing the pressure of the gas in the container relative to the pressure of the gas in the reference pressure vessel; and

e. means responsive to the sensing means to maintain the valve in its open position until a predetermined pressure differential between the gas in the container and the gas in the reference pressure vessel exists and to close the valve when the predetermined pressure differential exists. 10. The temperature compensated charging system claimed in claim 9 wherein:

a. a hollow member is provided, the member depending from the valve into the interior of the container;

b. the reference pressure vessel is carried by the hollow member; and

c. the interior of the hollow member is in gas communication with the valve in the latters open position and the interior of the container.

11. The temperature compensated charging system claimed in claim 10 wherein the reference pressure vessel is disposed in a housing which in turn is carried by the hollow member, the responsive means including a push rod within the hollow member and coupling the reference pressure vessel with the valve to maintain the valve in its open position until the predetermined pressure exists.

12. The temperature compensated charging system claimed in claim 11 wherein the responsive means includes means to bias the valve into its closed position.

13. A process for charging a predetermined quantity of a charge gas into a container regardless of container temperature comprising the steps of:

a. sensing the pressure of a given amount of reference gas in a reference vessel which reference gas has at least substantially the same temperature and characteristics as the charge gas;

b. charging the charge gas into the container from a high pressure source thereof under a condition where the reference gas is in thermal communication with the charge gas in the container and the temperature of the charge gas in the container and the temperature of the reference gas are essentially equal;

c. sensing the pressure of the charge gas in the container; and

d. terminating the charging of the charge gas into the container when there is a predetermined pressure differential between the charge gas in the container and the reference gas.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 77

DATED September 24, 1-974 INVENTOR(S) ROBERT w. McJONES It is certified that error appears in the ab0ve-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 23, "primariy" should read primarily line 37, "exits" should read exists line 41, "about" should read above line 45, "0" should read 0F. line 46 "2265F" should read 2265 Column 3, line 51, "hal" should read half line 52,

"half" should read and Column 4, line 65, "were" should read was Column 7, line 10, after "bellows" the period should be a comma Column 12,

line 48, claim 13, before "characteristics" insert pressure Signed and Scaled this twenty-ninth Day Of July 1975 [SEAL] A ties t:

RUTH C. MASON C. MARSHALL DANN A P X ffi (mnmissinncr uflarems and Trademarks

Claims

1. A temperature compensated charging system comprising: a. a constant volume container adapted to be charged with a gas from a high pressure source thereof; b. a closed reference vessel within the container containing a predetermined quantity of a gas under pressure and being in thermal communication with the container such that the gas in the reference vessel is at least substantially at the temperature of the bulk of the gas in the container even when the container is being charged with a gas and the pressure of the gas in the reference vessel is a direct function of the temperature therein and, hence, the temperature of the gas in the container, the gas in the reference vessel having at least substantially the same temperature-pressure characteristics as the gas to be charged into the container; c. means for sensing the pressure of the gas in the reference vessel; d. means for sensing the pressure of the gas in the container; e. valve means for selectively communicating the high pressure source of the gas to be charged into the container with the container; f. means responsive to both pressure sensing means to open the valve means and communicate the high pressure source with the interior of the container when there is less than a predetermined pressure differential between the gas in the interior of the container and exterior of the reference vessel on the one hand and interior of the reference vessel on the other and until there is the predetermined pressure differential at which time the responsive means closes the valve means to prevent communication between the container and the high pressure source of the gas; and g. whereby, the amount of gas charged into the container is essentially independent of the temperature thereof and essentially dependent on the predetermined pressure differential.

2. The temperature compensated charging system claimed in claim 1 wherein: a. the valve means includes a housing having a chamber, a first passage into the chamber for supplying gas from the high pressure source thereinto, a second passage into the chamber for discharging gas from the chamber into the container, and a valving element disposed in the chamber for movement therein between an open and a closed position to open and close the second passage to the chamber, respectively; and b. the responsive means is coupled to the valving element and the reference vessel such that the valving element is maintained open until the predetermined value is reached.

3. The temperature compensated charging system claimed in claim 2 wherein: the responsive means includes a push rod disposed between the valving element and the reference vessel; and the reference pRessure vessel has a pressure responsive element which is positionally responsive to the pressure within the container and the pressure within the reference vessel, the responsive element being coupled to the push rod and the push rod being coupled to the valving element to maintain the valving element in its open position until the predetermined value is reached.

4. The temperature compensated charging system claimed in claim 3 wherein: a member is included which is carried by the valve means; and the reference pressure vessel is carried by the member.

9. For use in charging a predetermined quantity of a gas into a constant volume, pressurized container from a high pressure source of the gas regardless of temperature, a temperature compensated charging system comprising: a. the container; b. a valve mounted on the container and having means for communication with the source of high pressure gas, the valve having an open position for gas passage into and out of the container and a closed position for preventing gas passage into and out of the container; c. a closed reference pressure vessel within the container, the reference pressure vessel containing a predetermined quantity of gas under pressure and being in thermal communication with the container such that the temperature within the reference pressure vessel is essentially the same as the temperature of the bulk of the gas in the container even during charging of the container with the gas from the high pressure source thereof, the gas in the reference pressure vessel having at least substantially the same pressure-temperature characteristics as the gas to be charged into the container; d. means for sensing the pressure of the gas in the container relative to the pressure of the gas in the reference pressure vessel; and e. means responsive to the sensing means to maintain the valve in its open position until a predetermined pressure differential between the gas in the container and the gas in the reference pressure vessel exists and to close the valve when the predetermined pressure differential exists.

10. The temperature compensated charging system claimed in claim 9 wherein: a. a hollow member is provided, the member depending from the valve into the interior of the container; b. the reference pressure vessel is carried by the hollow member; and c. the interior of the hollow member is in gas communication with the valve in the latter''s open position and the interior of the container.

13. A process for charging a predetermined quantity of a charge gas into a container regardless of container temperature comprising the steps of: a. sensing the pressure of a given amount of reference gas in a reference vessel which reference gas has at least substantially the same temperature and characteristics as the charge gas; b. charging the charge gas into the container from a high pressure source thereof under a condition where the reference gas is in thermal communication with the charge gas in the container and the temperature of the charge gas in the container and the temperature of the reference gas are essentially equal; c. sensing the pressure of the charge gas in the container; and d. terminating the charging of the charge gas into the container when there is a predetermined pressure differential between the charge gas in the container and the reference gas.