US20140319140A1 - Gas supply device - Google Patents

Abstract

A gas supply device comprises a gas capsule 2 having a diaphragm closure4. A cap10 having a passage12 therethrough is fixedly secured to the capsule2. There is a valve member14 in the passage12, The valve member14 has a forward face carrying a diaphragm-piercing device20 able to be urged by application of a force against the bias of a spring22 to pierce the diaphragm closure 4 to release gas from the capsule2. Removal of the diaphragm-piercing force, causes a rearward face30 of the valve member14 to be biased by the spring22 into a valve-closing position in which gas is retained in the capsule2.

Description

• This invention relates to a gas supply device, particularly one including a capsule for storing a gas under pressure, the capsule typically being of a size and weight that it can be readily held in the palm of a user's hand.
• Such capsules are commonplace. Such a capsule conventionally has a closure at its mouth in the form of a diaphragm that can be pierced in order to release gas. Capsules containing carbon dioxide or nitrous oxide at a pressure typically in the order of 60 bar are well known. Such capsules are typically used in conjunction with a separate unit for piercing the diaphragm, the separate unit being incorporated into the device to which the gas is to be delivered or into a separate device which can mate with a unit in which the gas is to be used.
• In a typical arrangement, disengagement of the capsule from the piercing unit results in the loss to the atmosphere of residual gas in the cylinder through the pierced diaphragm. An example of such an arrangement is, for example, disclosed in GB-A-971 161. A further disadvantage of such arrangements is that because the seal and piercing action are made essentially simultaneously, there is a risk that the diaphragm is pierced before a good face seal is effected, allowing high pressure gas to escape. Such escape is potentially hazardous. In addition, the escaped gas can penetrate screw threads between the capsule and the piercing unit and creates difficulty in tightening the capsule further due to the gas pressure acting on the threads.
• According to the present invention there is provided a gas supply device comprising:
• a capsule for storing a gas under pressure, the capsule having a mouth;
• a closure at the mouth of the capsule in the form of a pierceable diaphragm;
• a cap fixedly and permanently secured to the capsule over the said mouth;
• a passage through the cap permitting external access to the diaphragm;
• a valve member in the passage, the valve member having a forward face carrying a diaphragm-piercing device, and being able to be urged by application of a diaphragm piercing force against the bias of a spring to cause the diaphragm-piercing device to pierce the diaphragm and thereby release gas from the capsule into the passage, and a rearward face which on removal of the diaphragm-piercing force is biased by the spring into a volume-closing position in which gas is retained under pressure in the capsule.
• A gas supply device according to the invention is therefore able to retain for at least a period of time gas in the capsule if the diaphragm-piercing force is withdrawn.
• The cap typically has an external surface having a configuration enabling the gas supply device to be coupled to another device in which the gas is to be used. To this end, the said external surface of the cap conveniently has a screw thread.
• A gas supply device according to the invention typically has a valve member which is connected to or integral with a valve spindle, to which spindle the diaphragm-piercing force can be applied. Typically, the arrangement is such that the act of coupling the gas supply device according to the invention to the gas using device causes the diaphragm-piercing force to be applied.
• In one embodiment the spindle carries a seat for the spring. In this and other embodiments the spring may be a compression spring.
• The rearward face of the valve member typically seats against an O-ring seal. The O-ring seal may when the valve is closed is held under compression against an internal surface of the cap. In other embodiments, the rearward face of the valve member can carry an O-ring seal which is held under compression when the valve member seats against an internal surface of the cap.
• In some embodiments of the gas supply device according to the invention, the forward face of the valve member is integral with the diaphragm-piercing device. In other embodiments, the forward face of the valve member carries a piercing needle. The piercing needle may be hollow or formed with at least one longitudinal groove to facilitate the passage of gas out of the capsule on the piercing of the diaphragm. If the said external surface of the cap which is to be coupled to another device in which the gas is to be used is formed with a screw-thread, the axial extent of that screw thread is conveniently greater than the distance travelled by the valve member from its diaphragm-piercing position to its valve-closing position. This enables the capsule to be securely coupled to the other device in which the gas is to be used before the diaphragm can be pierced.
• The gas supply device according to the invention makes it possible to present a small effective area to the gas pressure thus facilitating coupling and uncoupling of the device to and from another device at higher working pressures. In addition, in embodiments in which the external surface of the cap has screw threads to engage with complementary screw threads in another device, the engaging threads are readily sealed from the capsule before the diaphragm is pierced.
• In embodiments of the gas supply device according to the invention in which the valve member is connected to or integral with a spindle, the spindle does not protrude out of the passage even when the valve is in its closed position. The valve therefore has protection from damage in the event of the capsule being accidentally dropped.
• A gas supply device according to the invention will now be described by way of example with reference to the accompanying drawings, in which:
• FIG. 1 is a general, schematic, sectional, side elevation of a gas supply device according to the invention;
• FIG. 2 is a sectional side elevation of the head of the gas capsule shown inFIG. 1 prior to the piercing of its diaphragm seal;
• FIG. 3 is a sectional side elevation illustrating the coupling of the cap of the gas supply device to a user device;
• FIG. 4 is a side elevation, not in section, of the coupling member shown inFIG. 3;
• FIG. 5 is a schematic drawing of an alternative form of valve head to that in the gas supply device shown inFIGS. 1-3; and
• FIG. 6 is a schematic drawing of an atmospheric pressure non-thermal gaseous plasma generating device which may be coupled to gas supply device according to the invention.
• For purposes for ease of illustration, the head of the gas capsule is not shown inFIG. 3.
• Referring toFIGS. 1-4, a gas supply device according to the invention comprises a gas capsule2 for storing a gas under pressure. The gas capsule2 has a closure4 at its mouth in the form of a pierceable diaphragm4 (seeFIG. 2).
• The capsule2 is typically of a size and weight such that it can be held comfortably in the palm of the human hand. It typically has a water capacity in the range of 5-50 ml. The capsule2 stores chosen gas under pressure. The storage pressure may be in the range of from under 25 bar to over 300 bar. The thickness and material of construction of the walls of the capsule2 are selected so as to withstand the chosen storage pressure.
• The capsule2 is therefore typically formed of a suitable steel such as stainless steel or of aluminium. The capsule2 shown in the drawings is of a conventional kind and may be made by known manufacturing processes.
• The diaphragm4 is typically formed of the same material as the capsule2. It is typically welded in position once the capsule2 has been charged with the chosen gas and the chosen pressure.
• The capsule may be filled with any chosen gas. Some non-permanent gases may liquefy when subjected to the chosen storage pressure. Accordingly, the capsule may store the gas in liquefied state. If, however, the gas or gas mixture to be stored is a permanent gas, the gas will remain in gaseous state when subjected to the storage pressure.
• The mouth of the capsule2 is provided by a cylindrical protuberance6 at the end of the capsule2. The exterior surface of the cylindrical protuberance6 is provided with a screw thread. It engages a complementary screw thread on acap10 having apassage12 formed therethrough, the longitudinal axis of thepassage12 being coaxial with the longitudinal axis the capsule2. The complementary screw threads are treated with a suitable adhesive such as sold under the trademark LOCTITE®. The adhesive cures at ambient temperature and has the effect of fixedly securing thecap10 to the protuberance6 of the capsule2. A user of the gas supply device shown inFIGS. 1-4 is therefore not able solely by manual means to unscrew or separate thecap10 from the capsule2.
• Thecap10 houses a diaphragm-piercing device14 within thepassage12. The diaphragm-piercingdevice14 is operable, as will be described below, to pierce or puncture the diaphragm4 of the capsule2 when it is desired to release gas from the capsule for the first time.Piercing device14 comprises ahead16 integral with aspindle18. In an alternative embodiment (not shown), thehead16 may be a separate part attached to thespindle18. The forward face of thehead16 is formed with a pointed piercingtip20.
• The piercingdevice14 is able to be urged forwards such that the piercingtip20 breaks through the diaphragm4 causing gas to be released from the capsule2. Displacement of the piercingdevice14 can be effected against the bias of acompression spring22. Thecompression spring22 is housed in thepassage12 and extends around thespindle18. Thespindle18 is fitted with a spring retainer24 of a “starlock” kind.
• Thehead16 of the piercingdevice14 has a dual function. As well as providing the piercingtip20, it acts as a valve member. Removal of a diaphragm-piercing force under the spindle causes the bias of thecompression spring22 to act against the spring retainer24 and causes the piercing device to be withdrawn from the diaphragm4 of the capsule2 to travel backwards towards a resilent O-ring seal26 retained on an inner surface28 (seeFIG. 3) of thecap10, Arearward face30 of thehead16 makes a sealing engagement with the o-ring26 and thereby prevents gas from passing beyond the seal. Gas pressure acting on a forward face of thehead16 holds thehead16 against the O-ring seal26. The piercingdevice14 thus functions as part of a valve which is able to be closed when the diaphragm4 has been pierced so as to prevent further passage of gas from the capsule2 to a user device.
• Referring particularly toFIG. 3, the external surface of thecap10 remote from the capsule2 is provided with an external screw thread40 to enable thecap10 and hence the capsule2 to be connected to agas delivery device42. Thegas delivery device42 has a hollow body44 with an internal screw thread complementary to that of the screw thread40. Thedevice42 can therefore be simply screwed on to thecap10 of the capsule2. Thedevice42 carries in its hollow body one end of aprobe50. The act of screwing thedevice42 onto thecap10 causes theprobe50 to bear against thespindle18 of the piercingdevice14 and urge the piercingdevice14 forward such that itstip20 pierces the diaphragm4. The length of the screw thread40 on the external surface of thecap10 and the length of the complementary screw thread in the body44 of thedevice42 is greater than the distance travelled by the piercingdevice14 from its valve-closing position to its diaphragm-piercing position. This enables the capsule2 to be securely coupled to thedevice42 before the capsule can be pierced. Theprobe50 is provided with an internal gas passage48 which communicates with a user device (not shown inFIGS. 1 to 4). Accordingly, when the piercingtip20 fully penetrates the diaphragm4 gas is able to flow from the capsule2 past the O-ring seal26 into the passage48 to the user device, In order to minimise loss of gas over the external surface of theprobe50, resilient O-ring seals51 and52 are provided between theprobe50 and an internal surface of thecap10 bounding thepassage12 and the body44 of theconnector device42, respectively, In the event that any gas does leak past the seal26, it may vent to the surrounding atmosphere through a slot54 (seeFIG. 4) formed in theconnector device42.
• Once a chosen volume of gas has been delivered to the user, thecap10 of the capsule2 may be unscrewed from thegas delivery device42, thus withdrawing theprobe50. As a result, the piercingdevice14 travels away from the diaphragm4 and itsrearward face30 makes sealing engagement with the o-ring seal26, thereby preventing passage of gas from the capsule2 past thehead16 of the piercing device2, The gas is thus retained in the capsule2 even though the diaphragm4 has been pierced or punctured.
• The screw thread40 on thecap10 and the complementary screw thread in the body44 of theconnector42 may have specific complementary dimensions for a particular gas. Thus the capsule2 may be dedicated to that gas. A capsule2 storing a different gas would have a screw-thread40 of different dimensions so that it could not be connected to aconnector device42 not designated for that particular gas.
• If desired, a small filter or screen can be retained around thespindle18 by thecompression spring22 so as to intercept any particles of the diaphragm4 that may be formed during its rupture by the piercingtip20.
• Various modifications may be made to the gas supply device according to the invention. One such modification is shown inFIG. 5. In this modification, the spring retaining device24 is omitted and thespindle18 of the piercingdevice14 is formed at its tail with anintegral stop500 which retains thecompression spring22. In another modification, theconnector device42 houses a pressure regulating valve (not shown) to reduce the pressure of the gas to a chosen value.
• The gas supply device according to the invention may be used to store and deliver either a permanent or a non-permanent gas. In one example, it may be used to store and deliver a noble gas, for example, helium or argon, or a mixture of helium and argon, to a device for administering a non-thermal gaseous plasma to the oral cavity of a human being.FIG. 6 is a schematic diagram of a helddevice601 for generating non-thermal gaseous plasma comprising a housing602 which defines a docking station603 receiving a gas supply device604 according to the invention. In this embodiment, the gas supply device604 comprises a 21 ml capacity gas capsule. The docking station603 is provided with a connecting device (not shown) of the same kind as the connectingdevice42 shown inFIG. 3. Full insertion of the gas supply device604 in the docking station603 causes the diaphragm of the gas capsule to be pierced and gas to be released from the gas capsule in the direction of the arrow. The docking station603 communicates with a gas passage606 in which the manually operable valve605 is located. This valve605 is normally closed so that on piercing the diaphragm of the gas capsule, none of the resulting release of gas can pass beyond the valve605. The valve605 is provided with a manually operable actuator608, which can be operated to open the valve605 to allow gas to pass therethrough. The passage606 communicates with acell610 for generating a non-thermal gaseous plasma, typically at atmospheric pressure. Theplasma generator cell610 is provided with an applicator612 which is able to be inserted into the oral cavity. Further information about the configuration and use of such devices in oral treatment is given in Patent Applications WO 2010/072997A, WO 2010/103262A and WO 2010/103263A, which are all incorporated herein by reference.
• The gas supply device604 may be removed from the docking station603. As a result of such removal, the valve mechanism described with reference toFIGS. 1 to 5 closes, thereby retaining gas under pressure in the capsule.

Claims (12)

1. A gas supply device comprising:

a capsule for storing a gas under pressure, the capsule having a mouth;

a closure at the mouth of the capsule in the form of a piercable diaphragm;

a cap fixedly and permanently secured to the capsule over the said mouth;

a passage through the cap permitting external access to the diaphragm;

a valve member in the passage, the valve member having a forward face carrying a diaphragm-piercing device, and being movable by application of a diaphragm-piercing force against the bias of a spring to cause the diaphragm-piercing device to pierce the diaphragm and thereby release gas from the capsule into the passage, and a rearward face which on removal of the diaphragm-piercing force is biased by the spring into a valve-closing position in which gas is retained under pressure in the capsule.

2. The gas supply device according toclaim 1, wherein the cap comprises an external surface having a configuration enabling the gas supply device to be coupled to another device in which the gas is to be used.

3. The gas supply device according toclaim 2, wherein said external surface of the cap comprises a screw thread.

4. The gas supply device according toclaim 1, further comprising a valve spindle to which the valve member is at least one of connected to or integral with the valve spindle, and against which the diaphragm-piercing force can be applied,

5. The gas supply device according toclaim 4, wherein the spindle further comprises a seat carried on said spindle for the spring.

6. The gas supply device according toclaim 1, wherein the spring is a compression spring.

7. The gas supply device according toclaim 1, wherein further comprising an o-ring against which the rearward face of the valve member can be seated, the o-ring being held under compression against an internal surface of the cap when the valve is in a closed position.

8. The gas supply device according toclaim 1, wherein the forward face of the valve member is integral with the diaphragm-piercing device.

9. The gas supply device according toclaim 1, wherein the valve member further comprises a piercing needle carried on the forward face of said valve member.

10. The gas supply device according toclaim 9, wherein the piercing needle comprises at least one longitudinal groove to facilitate flow of gas from the capsule upon piercing of the diaphragm.

11. The gas supply device according toclaim 1, wherein the cap further comprises an external screw-threaded surface adapted to be coupled to a gas-using device, the external screw-threaded surface having an axial extent being greater than a distance travelled by the valve member from its diaphragm piercing position to its valve closing position.

12. The gas supply device according toclaim 1, further comprising a filter or a screen disposed at the passage and adapted to prevent transmission of solid particles formed by the piercing of the diaphragm.

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