GB2252147A - Control of a gas flow - Google Patents

Abstract

A valve for the control of a gas flow has two cylindrical members 2, 4 adjacent to one another and defining a flow passage. Secured between the cylindrical members is a sleeve of gas-impermeable material, for example coated nylon, folded back on itself. In the valve condition shown gas may flow through the sleeve without hindrance. When one member 2, 4 is turned relative to the other, the sleeve is twisted, to form a narrowed aperture, so restricting the gas flow. Ultimately, the restricted aperture may disappear, the sleeve then forming a tautened barrier substantially preventing gas flow altogether. The valve is particularly used for controlling flow of air in air-conditioning apparatus. <IMAGE>

Description

CONTROL OF A GAS FLOW This invention relates to the control of a gas flow, by means of a valve having a flexible sleeve secured between members which are capable of relative turning movement. Relative turning movement of the members causes the sleeve to change from a condition in which it causes substantially no hindrance to a gas passing through the valve, to a twisted position in which it substantially prevents a gas passing through the valve, via intermediate positions in which a gas is permitted to pass only through a central aperture within the sleeve.

The invention is of particular interest in the field of the air flow control.

GB 535489 describes a valve having annular members adjoining one another and having a sleeve of flexible material secured therebetween, folded back on itself, such that relative turning of the annular members affects the condition of the sleeve, which acts as a control member.

The valve is said to be useful for the control of solids or liquids, and is particularly intended for use in interrupting the downward flow of divided material, such as flaky gelatine.

Valves are also known, in which annular or cylindrical members are spaced well apart, with a sleeve comprising an elastomeric material secured therebetween in a generally tubular (unfolded) configuration. One example is described in EP-A-334519, and this is said to be useful in controlling an air flow. The sleeve thereof is formed from a close-mesh textile material at the inlet end, and an elastomeric material, secured thereto, at the outlet end. This arrangement is said to reduce vibration noises, often referred to as "drumming", associated with earlier valves having one-piece sleeves made of elastomeric materials, used to control air flow.

However, valves of the type described in EP-A-334519 are still found to be undesirably noisy, and, moreover there is an inherent problem, in that an elastomeric material must be employed in the sleeve, preferably a natural rubber, and such materials are prone to degradation, for example during storage or in sunlight.

Furthermore, the valve of EP-A-334519 requires the securing together of the two end portions of the sleeve, and whether a sewing or gluing method is used, problems can arise. In use, the sleeve undergoes considerable twisting. Great care has to be taken during manufacture if the integrity of the seam is to be maintained in use.

In accordance with the present invention there is provided the use of a valve to control the flow of a gas, the valve comprising two members which are adjacent to one another, and which are substantially axially aligned, to define at least a portion of a flow pathway, between which members a flexible open-ended substantially gasimpermeable sleeve of a sheet material is secured, such that it is folded back on itself therebetween, the members being capable of relative turning movement to twist the sleeve and thereby restrict or prevent the flow of gas along the pathway, but being substantially incapable of relative axial movement.

Preferably, the members are cylindrical or annular, and the sleeve is a circular cylinder of material, folded back on itself when installed in the valve.

Preferably, each member is connected to a respective end of the sleeve.

When the valve is maximally open, the sleeve is in a loose configuration, for example, in folds, flaps or ruches, and on the passage of a gas through the valve the sleeve tends to be blown against the wall of the downstream member, in a surprisingly regular fashion and in such a way as to provide little or substantially no hindrance to the passage of the gas through the valve. As relative turning of the members takes place the sleeve twists and tautens, and as it does so the opening through the sleeve reduces.

Preferably, use of a valve in accordance with the present invention is in the control of air flow.

Preferably, the sleeve is non-elastomeric in its properties. Preferably, the sleeve comprises a close-mesh textile material. A particularly preferred material is a close-mesh nylon material. It may be coated on one or both sides, to improve its gas impermeability, for example with polyurethane, and/or for flame retardancy. A particularly preferred material is a high tensile nylon 66.

A particularly preferred material for the sleeve is a ripstop nylon material suitable for parachutes or hot air balloons. Such a material is of course extremely durable, has very good tear strength and tensile breaking strength, and is substantially air impermeable.

Preferably, the two members are secured together, preferably releasably, in such a way as to permit relative turning movement but to substantially prevent relative axial movement. For example, when the members are annular or cylindrical, one member may have an external annular detent-providing part, for example a groove or rib or band, and the other member may have one or more external members, for example spring clips, with portions which engage the said detent-providing part, for example within the groove or over the rib or band.

The valve described herein, used to control gas flow, gives particularly quiet operation and may have a longer life than prior art valves disclosed for this purpose, for example the valve of EP-A-334519, which employ elastomeric material.

In accordance with a second aspect of the present invention there is provided air conditioning apparatus comprising an air flow passage in which is mounted a valve, as described or defined herein.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows the junction zone of two cylindrical members of a valve, in external side view; Fig. 2 corresponds to the view of Fig. 1, but in longitudinal cross-section through the axis of the valve; Fig. 3 is a similar view to Fig. 2, showing part of Fig.

2 in larger scale; Fig. 4 is a similar view to Fig. 2 but with the valve in a restricted flow condition; and Fig. 5 is a similar view corresponding to Figs. 2 and 4, but with the valve fully closed.

The valve, which is for use in air conditioning equipment, comprises two cylindrical members 2, 4, which together define an air flow passage. They are located in end-to-end relationship, in axial alignment, in close proximity to each other, with just a very small clearance 6 between them. The member 4 is formed with an external circular groove 8, and the member 2 has mounted on its external surface three spring clips 10 at 1200 intervals, each of which is formed with a respective tang 12 at its end, slidably received in the groove 8. Thus, members 2, 4 are in fixed relationship, transversely and longitudinally, but member 4 may be turned relative to member 2, as indicated by the arrow in Fig. 1.

A sleeve 14, acting as a valve control member, being of close-mesh textile sheet material, non-elastomeric in its properties, and substantially air-impermeable, is provided in the region of the junction of the members 2, 4. The sleeve 14 is circularly cylindrical and one circular end thereof is secured to member 2 adjacent the junction 6 and its other circular end is secured to the member 4 adjacent the junction 6. More specifically, the end of each cylindrical member has a small stepped portion 16, 18 reamed out, and the respective circular end of the control member is secured, with the aid of adhesive, between the respective reamed out portion 16, 18 and a respective fixing ring 20, 22. The construction is most clearly shown in Fig. 3.

The operation of the valve will now be described.

In Fig. 2, the valve is shown in its fully open condition. The sleeve 14 is completely untwisted, and the air passing through the valve in the direction of the arrow, pushes the sleeve against the internal wall of the downstream member 2, so that the sleeve provides substantially no hindrance to the flow of air.

In Fig. 4, the valve is shown in a restricted condition. Member 4 has been turned until the sleeve is twisted to leave a limited central aperture A for the passage of air. It will be observed that the control member is acted upon by the flowing air so as to form a generally frusto-conical shape with the aperture A somewhat downstream of the junction 6. It has been found in experiments, that the aperture A is of surprisingly regular, indeed approximately circular, shape.

In Fig. 5, the valve is shown in its fully closed condition, the member 4 having been maximally turned, relative to member 2. The sleeve has been twisted to form a tight band right across the flow passage, with no aperture for the passage of air.

The member 4 may be turned by any convenient means, for example via a belt, via a direct drive from an electric motor or gearbox, by hydraulic or pneumatic means, or by manual actuation.

The characteristics of the sleeve material will now be described further. In this embodiment it is a ripstop nylon material available from Carrington Novare, of Dewsbury, West Yorkshire, U.K., as N1053 grade, as used for parachutes and hot air balloons. It is a fine mesh woven nylon material, the nylon being a high tensile nylon 66, coated on one side with polyurethane and fluorocarbon coating. The weight is about 50 g/m2. The tensile and tear strengths are high and the air permeability, as measured in accordance with British Standard 5636, is less than 0.10 cm3/cm2/s. In effect, the material is substantially air-impermeable. In this embodiment it is formed from a flat sheet, being sewn along a longitudinal seam, to parachute seam standards. In other embodiments it could be woven or knitted as a seamless tube.

A valve'of the type described above was tested at different air flow rates, in comparison with a valve of the type described in EP-A-334519, which has a two-part control member formed from an elastomeric material linked to a woven textile material. The valve of the present invention gave the lower noise output in each of the tests.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

Claims (7)

1. Use of a valve to control the flow of a gas, the valve comprising two members which are adjacent to one another, and which are substantially axially aligned, to define at least a portion of a flow pathway, between which members a flexible open-ended substantially gas-impermeable sleeve of a sheet material is secured, such that it is folded back on itself therebetween, the members being capable of relative turning movement to twist the sleeve and thereby restrict or prevent the flow of gas along the pathway, but being substantially incapable of relative axial movement.

2. Use of a valve as claimed in Claim 1, wherein the said members of the valve are cylindrical or annular.

3. Use of a valve as claimed in Claim 1 or 2, wherein the sleeve of the valve is of a nylon material.

4. Use of a valve as claimed in any preceding claim, wherein the members of the valve are secured together, in such a way as to permit relative turning movement but not relative axial movement.

5. Use of a valve as claimed in any preceding claim, wherein each member is secured to a respective end of the sleeve.

6. Air conditioning apparatus comprising air flow ducting in which is mounted a valve as defined in any of Claims 1 to 5.

7. Use of a valve in air conditioning apparatus, substantially as hereinbefore described with reference to the accompanying drawings.