GB2237366A - A valve assembly - Google Patents

Abstract

A valve assembly for delivering gas from a cylinder or bottle comprises a valve body (1) which is located in the outlet from a pressurised container. The valve body (1) defines a flow path in which a first valve arrangement (4, 5) and a second valve arrangement (21) are located, the first valve arrangement (4, 5) closing when the delivery pressure from the pressurised container exceeds a preselected value in the flow path. The second valve arrangement (21) is a shut-off valve, which opens upon attachment to a device to be supplied with gas. Means (12, 13, 14, 16, 17) are provided for maintaining the first valve arrangement (4, 5) in an open position to permit re-filling of the container through the flow path. <IMAGE>

Description

A VALVE ASSEMBLY The present invention relates to a valve assembly. More particularly, the present invention relates to a valve assembly which is primarily, but not exclusively, intended for use in delivering gas from a pressurised container but which can also be used in replenishing the container with gas at an elevated pressure.

It is extremely well known to store gas in cylinders and, almost invariably, such gas is stored at an elevated pressure. The use of an elevated pressure is desirable both from the point of view of the gas manufacturer and also from the point of view of the end user. It will be readily apparent that the manufacturer is selling gas rather than the cylinder and the higher the pressure, the more gas he can use to fill a cylinder.

Insofar as the end user is concerned, the more gas there is present in a full cylinder, the less frequently the cylinder needs to be replenished or replaced.

However, in storing a gas as an elevated pressure in a cylinder, certain problems arise. It is obviously necessary to provide some form of valve means for allowing the gas to be used and for preventing gas escaping from the cylinder when such use has terminated.

In its simplest form, one such arrangement is a valve member which is closed when the provision of gas is not required but which can be opened, by any one of a number of suitable means,to allow the passage of gas there through. A simple valve arrangement of this type offers the advantage that, when the cylinder is empty, it can be replenished simply by opening the valve and connecting the empty cylinder to a source of fresh gas.

Such a valve arrangement does, however, present one major disadvantage. As previously mentioned, the cylinder, when full, contains gas at an elevated pressure. Accordingly, merely opening the valve means that the gas is supplied to the end-user at substantially the same pressure as that prevailing within the cylinder.

Accordingly, regulator valves are usually provided in conjunction with gas cylinders so as to ensure that the pressure of gas supplied to the end user is at a desired level, irrespective of the pressure of the gas within the cylinder. In one known type regulator valve, there is provided a valve body defining a chamber in which a valve member is slidably displaceable. The valve member acts on a closure member which opens and closes an inlet to the chamber from the gas container. The valve member also defines a flow path for the gas and is normally spring-biassed into a position in which the inlet is open.

Moreover, the pressure of the gas entering the chamber acts on the valve member which also tends to maintain the inlet open. However, before being discharged to an outlet, the gas passes into a further chamber communicating with the end of the chamber in which the valve member is located remote from the inlet. The pressure of the gas in this further chamber acts in a direction opposing the force of the spring and the force of the gas entering through the inlet of the valve member chamber. By appropriately selecting the characteristics of the spring, it may be ensured that the valve member is automatically caused to move and close the inlet when the pressure in the further chamber exceeds a predetermined value. This action increases the volume of the further chamber and the pressure of the gas therein falls.Moreover, since the supply of gas to the valve member has been temporarily terminated, the pressure of the gas present in the valve will further fall.

In addition, such a valve will function in the above-described manner if the pressure of the gas entering the inlet drops below a particular value. This will occur if the gas container is virtually empty.

Whilst such a regulator valve arrangement is extremely useful for enabling the end-user to utilise the gas in the container such as a cylinder, the very nature of the valve causes problems if an attempt is made to refill an empty cylinder. It will readily be appreciated that, if the flow of gas described hereinbefore is reversed, the outlet from the further chamber becomes the inlet for the gas being used to recharge the cylinder. It is therefore inevitable that a pressure will build up in this chamber before any gas has had the opportunity to pass along the flow path, around the closure member and into the conduit leading into the gas cylinder. Since the refilling is done at a very high pressure, the regulator valve member will act to close the conduit, thereby preventing filling of the cylinder.

Attempts have hitherto been made to overcome this problem, most noticeably by providing the assembly with a separate filling port which, effectively, bypasses the regulator valve. However, the provision of an extra port to enable such filling to take place incurs increased manufacturing costs and inevitably leads to the bulkiness of the valve assembly being substantially increased. The present invention therefore seeks to provide a valve assembly suitable for use in conjunction with a cylinder or bottle which provides regulation of the gas flow from the cylinder or bottle to a workpiece when the device is in use but which permits the gas bottle or cylinder to be replenished when empty by permitting gas to flow through the regulator valve.

According to the present invention, there is provided a valve assembly for delivering gas from a cylinder or bottle comprising a valve body locatable in an outlet from a pressurised container, the valve body defining a flow path therethrough in which first and second valve means are disposed, the first valve means being disposed to close when a preselected delivery pressure from the pressurised container is exceeded in the flow path and the second valve means being a shut-off valve disposed to be openable upon attachment to a device to be supplied with gas, wherein means are provided for maintaining the first valve means in an open position to permit the refilling of the container through said flow path.

In a preferred embodiment of the present invention, the first valve member includes a stepped chamber disposed in the valve body, a hollow piston member slidably disposed within said chamber, the hollow interior of the piston forming part of said flow path, the piston including a head portion, spring biassing means disposed within said chamber around said piston, said spring being disposed between said shoulder portion of said chamber and the underside of said head portion whereby said spring is disposed in an annular compartment of said chamber and is isolated from the flow path, said annular compartment including means for supplying a filling gas thereto simultaneously with the introduction of said filling gas into said flow path, whereby said piston member is maintained in its open position.

In some regulator valves, the compartment in which the spring is located communicates with a breather port. In a desirable embodiment of the present invention, a port communicates with the compartment in which the spring is located, said port constituting an inlet port for the filling gas utilised to maintain said piston in its open position. Alternatively, an additional conduit arrangement may be provided for supplying filling gas to the compartment containing said spring.

In an advantageous embodiment of the present invention, a hood member having conduit means defined therein is provided simultaneously for supplying filling gas to said flow path and to said compartment in which said spring is located.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic side view of a valve assembly in accordance with the present invention; and Figure 2 is a schematic side view of a hood assembly suitable for use in conjunction with the valve assembly shown in Fig. 1.

In Fig. 1 there is shown a valve assembly in accordance with the present invention. The valve assembly comprises a valve body 1 which is locatable in the outlet lrom a pressurised container (not shown) such as a cylinder or bottle. Defined within the valve body 1 is a conduit 2 leading from the cylinder or bottle to a stepped chamber 3. Within the chamber 3, a first valve member is provided. Such valve member comprises a closure member 5 located adjacent the inlet 4, which member is slidably displaceable within the reduced diameter portion 6 of the stepped chamber 3 by means of a piston 7. The piston has a head portion 8 and has a centrally disposed bore 9 extending therethrough.The piston is provided with grooves 10 and 11 around its periphery , in both the reduced diameter portion and in the main portion of the chamber 3, in which O-ring seals 12 and 13 are located, which latter provide a gas-tight seal between the piston and the internal wall of the chamber 3.

Around the periphery of the piston 7, in the main body of the chamber 3, an annular compartment 14 is defined. Within this compartment 14, a spring 15 is provided. One end of the spring 15 abuts against the underside of the head 8 of the piston 7 and the other end of the spring abuts against the shoulder portion 36 of the stepped chamber 3. Extending radially outwardly through the wall of the valve body 1 from the compartment 14 is a breather conduit 16 which is open to the atmosphere through a port 17.

The outlet 18 of the bore 9 in the piston 7 opens into a further chamber 19 located on the opposed side of the piston head 8 from the compartment 14. The outlet from the chamber 19 leads into an inlet conduit 20 of a second valve member in the form of a shut-off valve 21. Tht shut-off valve 21 is a simple valve arrangement comprising a closure member 22 which is provided with an appropriate seat 23. The closure member 22 is attached to a rod 24 or the like which is actuated by a workpiece or article being attached to the free end 25 thereof. The conventional use of such a valve assembly will now be described. Gas in the cylinder is caused to be discharged therefrom by means of a suitable control member (not shown) and such gas then enters the conduit 2. The gas then passes into the reduced diameter portion 6 by raising the closure member 5 from the inlet 4.Such displacement of the closure member 5 is possible because the spring 15 normally acts to bias the piston away from the inlet 4. The gas flows around the periphery of the closure member 5 and into suitable channels formed between the base of the piston 7 and the closure member 5 and into the bore 9 of the piston 7.

The gas then enters the chamber 19. The gas can only leave the chamber 19 through the inlet conduit 20 of the shut-off valve 21 and enters the chamber of the valve 21. The plunger 24 of the valve 21 is depressed against the force of a spring 21a by the affixing of a workpiece, tool or article, to the free end 25 thereof.

If no workpiece, tool or article is attached, the closure member 22 of the valve 21 will remain seated on its seat 23 and will not permit the passage of gas therethrough.

However, in this instance, it will be assumed that a workpiece is so fitted and that gas can flow through the valve 21.

It -ill be readily apparent from the foregoing that the first valve member is a regulator valve. Thus, for example, it will readily be seen that if the pressure downstream of the piston head 8 exceeds the pressure acting on the closure member 5 and the force of the spring 15, the piston will be forced to moved in a direction such as to compress the spring 15, thereby maintaining the closure member 5 away from the inlet 4 to the chamber 3.

Such a situation may, of course, occur if the gas cylinder or bottle from which the gas is being withdrawn is nearly empty.

It will now be assumed that it is desired to replenish the cylinder with pressurised gas. A fresh supply of gas is therefore connected to the original outlet 25 of the shut off valve 21. In so doing, the closure member 22 of the valve 21 will be moved from its seat 23. Gas can now flow through the original inlet conduit 20 of the shut off valve 21 into the chamber 19.

However, as soon as this occurs, the pressure of the incoming gas behind the piston head 8 will exceed the force of the spring and the residual pressure acting on the closure member 5 which, in turn, acts on the free end of the piston 7. Accordingly, the piston will again move from right to left as shown in Figure 1, thereby closing off the original inlet 4, thereby preventing any replenishment gas entering the conduit 2.

Accordingly, if a gas cylinder or bottle is to be replenished in this manner, some means must be found of ensuring that the piston is not displaced by the pressure prevailing in the chamber 19. To achieve this, gas at the same pressure as that entering the conduit 27 is simultaneously caused to pass through the port 17 and the conduit 16 into the compartment 14 in which the spring is located. It will bU recalled that the chamber 14 is isolated from the flow channel through the valve assembly and is also sealed by means of the O-rings 12, 13. The pressure thus prevailing in the compartment 14 acts on the underside of the piston head and counterbalances the pressure prevailing in the chamber 19. Accordingly, the piston will remain in its position shown in Figure 1 thereby providing a flow path for the gas in the chamber 19 which passes through the bore 9, around the periphery of the closure member 5 and into the conduit 2.

Shown in dotted lines in Figure 1 is an alternative version of an inlet conduit to the chamber 14.

This conduit 28 leads into the breather conduit 16. It will be readily apparent that, when the valve assembly is being used for replenishing a gas cylinder or bottle, the breather port 17 will be closed by means of a plug. To achieve the supply of replenishment gas to the conduit 28 and to the conduit 27 simultaneously, a hood 29 is employed. The hood includes a common inlet 30 for gas emanating from a source thereof (not shown). The inlet 30 is bifurcated to provide conduits 31, 32, communicating respectively with the conduits 27, 28.

It will be readily apparent to those skilled in the art that various minor modifications can be made to the valve assembly of the present invention without departing from the scope thereof. Thus, for example, the chamber 19 may be connected to a conventional pressure relief valve 33. Since the pressure relief valve itself forms no part of the present invention, it will not be described further. Furthermore, it will be readily apparent that the chamber 19 is sealed around its periphery by a further O-ring 34.

In the preferred embodiment of the present invention, the first valve member is maintained in its open position during refilling of the container by the gas used for replenishment. However, it will be apparent that there are other ways in which this can be achieved. For example a diaphragm could be utilised or the piston in the preferred embodiment may be held in its desired location by mechanical means.

Claims (6)

1. A valve assembly for delivering gas from a cylinder or bottle comprising a valve body locatable in an outlet from a pressurised container, the valve body defining a flow path there through in which first and second valve means are disposed, the first valve means being disposed to close when a preselected delivery pressure from the pressurised container is exceeded in the flow path and the second valve means being a shut off valve disposed to be openable upon attachment to a device to be supplied with gas, wherein means are provided for maintaining the first valve means in an open position to permit the refilling of the container through said flow path.

2. A valve assembly as claimed in claim 1 wherein the first valve member includes a stepped chamber disposed in the valve body, a hollow piston member slidably disposed within said chamber, the hollow interior of the piston forming part of said flow path, the piston including a head portion, a spring biassing means disposed within said chamber around said piston, said spring being disposed between said shoulder portion of said chamber and the underside of said head portion whereby said spring is disposed in an annular compartment of said chamber and is isolated from the flow path, said annular compartment including means for supplying a filling gas thereto simultaneously with the introduction of said filling gas into said flow path, whereby said piston member is maintained in its open position.

3. A valve assembly as claimed in claim 2 wherein a port communicates with the compartment in which the spring is located, said port constituting an inlet port for the filling gas utilised to maintain said piston in its open position.

4. A valve assembly as claimed in claim 2 wherein an additional conduit arrangement is provided for supplying filling gas to the compartment containing said spring.

5. A valve assembly as claimed in any preceding claim wherein a hood member having conduit means defined therein is provided simultaneously for supplying filling gas to said flow path and to said compartment in which said spring is located.

6. A valve assembly as claimed in claim 1 substantially as hereinbefore described with reference to the accompanying drawings.