GB1589464A

GB1589464A - Valve devices for controlling the flow of fluids

Info

Publication number: GB1589464A
Application number: GB1763476A
Authority: GB
Original assignee: Concentric Controls Ltd
Current assignee: Concentric Controls Ltd
Priority date: 1977-08-01
Filing date: 1977-08-01
Publication date: 1981-05-13

Description

(54) VALVE DEVICES FOR CONTROLLING THE FLOW OF FLUIDS (71) We, CONCENTRIC CONTROLS LIMI TED, a British Company of Priory Road, Aston, Birmingham 6, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to valve devices for controlling the flow of fluids.

Valve devices in accordance with the present invention incorporate expansion devices of the kind (hereinafter referred to as the kind specified) comprising an expansion element comprising two discs interconnected at their peripheries and defining between them an expansion chamber having a fluid inlet, the first of the two discs being supported at or near its centre, and the element being flexible and resilient so that when fluid is introduced through the inlet into the chamber the element expands, and when fluid is allowed to leave the chamber the element contracts again, at least partially due to the innate resilience of the element.

According to the present invention there is provided a valve device comprising a valve seat and a valve member with an abutment portion which is movable relative to the valve seat and co-operates with the valve seat to form a valve, and an expansion device of the kind specified, the first disc of the expansion element being flexible and resilient and comprising a circular piece of sheet metal formed with concentric corrugations, and the abutment portion of the valve member being constituted by an outer marginal part of the expansion element or by a part of the expansion element which in use moves substantially in unison with that outer marginal part, or by a part connected to the expansion element so that in use it moves substantially in unison with that outer marginal part.

In one type of valve device both the discs of the expansion element are flexible and resilient. When that type of valve device is in use and fluid is introduced into the expansion chamber both discs assume shapes that are slightly more part-spherical or slightly more part-spherical than they were initially. Therefore the part of the element that moves to the greatest extent relative to the support is the central part of the second disc, the marginal part of the element moving to a lesser extent.

Such an arrangement may be entirely acceptable. In another type of valve device only the first disc is flexible and resilient, the second disc being rigid. In that type of valve device the part of the element that moves to the greatest extent relative to the support is the while of the second disc. In either type of valve device the maximum effective travel of the marginal part of the element relative to the support is entirely determined, or almost entirely determined, by the flexing characteristics of the first disc.

Thus whether the second disc is flexible or rigid the maximum effective travel of the marginal part of the element is substantially the same, though the maximum volume of the chamber is greater when both discs are flexible than when only the first disc is flexible. Thus for each incremental increase in the volume of fluid introduced into the chamber in use, the movement of the marginal part of the element is less when both discs are flexible than is the case when only the first disc is flexible.

The outermost corrugation of the corrugated first disc may constitute the abutment portion of the valve member and co-operate with the valve seat; then, when fluid is introduced into the expansion chamber the abutment portion moves away from the valve seat thus causing the valve to open.

In the arrangements described above the arrangement is generally such that closure of the valve occurs on contraction of the expansion element. In an alternative arrangement, however, the arrangement is such that closure of the valve occurs on expansion of the expansion element. In such an arrangement the abutment portion of the valve member would usually comprise part of the second disc or be attached to the second disc. If the second disc is flexible and resilient, for example if it is corrugated, the marginal part of the disc may constitute or be attached to the abutment portion of the valve. If on the other hand the second disc is rigid any part of the second disc may constitute such an abutment portion or may be attached to the abutment portion, because the whole of the second disc moves in unison with the marginal part of the expansion chamber.

The arrangement may be such that on some occasions in use more fluid is introduced into the expansion chamber than is required to cause the valve to close. The first disc is normally capable of some resilient distortion in such a manner as to permit an increase in the volume of the expansion chamber after the valve has closed. The second disc may also be such that it too is capable of resilient deformation to permit such an increase in volume. In addition, however, to avoid the possibility of damage in those circumstances, the valve seat of the valve may be capable of yielding, or a yielding abutment member may be attached to the second disc for engagement with the valve seat. When yielding means of that kind is employed, the introduction of more fluid into the expansion chamber after the valve has closed will cause the second disc to be displaced as a whole.

In a further alternative there are two valves, the arrangement being such that closure of one valve occurs on contraction of the expansion element and closure ofthe other valve occurs on expansion of the expansion element.

Embodiments of the present invention will now be described in greater detail, by way of example, and with reference to the accompanying drawings, in which: Figure 1 is a section through a first type of valve device embodying the present invention, and Figure 2 is a section through a second type of valve device embodying the present invention.

The device shown in Figure 1 is intended for use in controlling the supply of combustible gas to a burner (not shown) and constitutes a so-called mercury flame-failure valve. The device comprises a housing 10 of which the interior constitutes a valve chamber. The valve chamber is in two parts, an inner part 11 of cylindrical shape and an outer part 12 which is also of cylindrical shape but is of larger diameter than the inner part. The two parts are co-axial, and where they meet there is an annular planar face directed towards the outer part of the chamber. A resilient ring 13, made for example from silicone or nitrile rubber, is mounted against that annular face and provides the valve seat.

The housing 10 is formed with an inlet opening 14 leading radially into the outer part 12 of the chamber and an outlet opening 15 leading radially from the inner part 11 of the chamber. An internally screw-threaded hole is also formed in the housing, the hole being co-axial with the valve chamber and leading into the inner part of the valve chamber. The hole extends through a boss 16 integral with the housing and projecting into the chamber.

An externally screw-threaded sleeve 17 extends through the hole. Its outer end has diametrically opposed slots 18 enabling it to be rotated, and the sleeve carries a lock-nut 19.

An expansion device of the kind specified is mounted in the valve chamber. The device includes a tubular metal support 20 of which one end portion is of reduced external diameter and fits into the bore of the sleeve 17.

The other, broader end of the support 20 is secured to the centre of the first disc 21 of an expansion element disposed in the outer part 12 of the valve chamber. The disc 21 has a central inlet hole communicating with the bore of the support 20. The disc is formed with a plurality of concentric corrugations so that any cross-section in a plane containing the axis of the disc is of generally wavy, sinusoidal shape. The peripheral part of the disc extends in direction normal to the main plane of the disc, and away from the inner part 11 of the valve housing, to form a shallow cylindrical ring 22. A second disc 23 is disposed in that ring and is welded or otherwise secured to it in a fluid-tight manner.The second disc 23 is planar and is of consideratly thicker metal than the first disc; in use it does not flex to any significant extent and can therefore be termed rigid.

During assembly of the valve the support 20 is pushed into the bore of the sleeve 17, and the sleeve is mounted in the hole in the boss 16 and is rotated to bring the expansion element to the desired position. The sleeve is secured in place by the lock-nut 19, and sealing material 24 is used to provide gas-tight seals between the components. In the desired position of adjustment the first disc 21 is resiliently distorted to a small extent so that when the fluid pressure in the expansion chamber, inside the expansion element, is equal to the fluid pressure outside the expansion element the resilience of the first disc urges the marginal part of the disc into sealing engagement with the resilient ring 13 affording the valve seat.

One end of a narrow metal tube 25 is sealed into the support 20. The tube extends from the outer end of the support and terminates in a tubular phial 26 of greater diameter than the tube. The phial 26, the tube 25 and the expansion chamber contain mercury.

It may be desirable to increase the sealing pressure exerted by the marginal part of the first disc 21 on the valve seat. This may be effected with the aid of spring means. In a typical arrangement, illustrated in Figure 1, a compression spring 27 is disposed in the outer part 12 of the chamber and acts between the second disc 23 and a part of the housing 10 facing the disc; the spring 27 is of frusto-conical shape, its narrower end bearing on the second disc, around the boss 28 secured to the centre of the disc.

The valve operates in the following manner: The inlet opening 14 of the valve is connected to a source of combustible gas, while the outlet opening 15 is connected to a main gas burner (not shown). A pilot burner from which the main gas burner can be lit is supplied with gas by another path. The phial 26 is so positioned as to be heated by the pilot burner. In normal use the mercury in the phial boils and some of it vapourizes, filling the phial and forcing the remaining liquid mercury from the phial into the tube 25. This in turn forces mercury from the other end of the tube into the expansion chamber. The first disc 21 is resiliently distorted in such a manner that the marginal part is lifted clear of the valve seat 13 and gas is thus permitted to pass from the inlet opening to the outlet opening and thence to the main burner.Should the gas supply be turned off or cease for some other reason the mercury cools and the valve closes, it then being impossible to restore the gas supply to the main burner without first relighting the pilot burner.

In a typical construction of valve device, intended for use with natural gas or l.p. gas, the discs 21 and 23 are about one inch in diameter and the gap between the first disc 21 and the seat 13 when the valve is open is between ten and fifteen thousandths of an inch.

A similar construction of valve device may be used in a thermostat, but in that case the mercury is replaced by an oil that expands when heated but does not vapourize. Also it is preferred not to use a resilient ring to provide the valve seat but to use instead the annular planar face of the valve housing. The reason for this is that the position of the valve seat is then absolutely constant; if a resilient ring were used the position of the sealing face might vary somewhat in use so that the thermostat settings would not remain constant.

Although there may be a slight gas leakage when the valve is nominally closed due to the fact that closure is effected by a metal-tometal engagement, this does not normally matter as a thermostat usually employs a gas by-pass through which there is a constant flow of gas sufficient to keep the burner alight even when the thermostat valve is closed. Any slight leakage through the nominally closed thermostat valve would not significantly affect the total gas flow to the burner, most of which is by way of the by-pass.

The valve device illustrated in Figure 2 is largely similar to that shown in Figure 1, and those parts of the second valve device that are similar to corresponding parts of the first valve device are given the same reference numerals. Parts of the second device that are not illustrated are similar to the corresponding parts of the first device.

The device illustrated in Figure 2 includes a second valve in addition to a first valve of the kind described above. The second valve controls the flow of gas from the outer part 12 of the valve chamber to an outlet duct 30. The mouth of the outlet duct 30 is surrounded by a tubular formation 31 which projects axially into the outer part of the valve chamber and terminates in a planar annular seating face 32.

In this type of device the spring 27 and boss 28 are omitted. The arrangement is such that in use when the expansion element expands the second disc 23 is brought into engagement with the seating face 32 and thus closes the second valve. In a modification either the seating face 32 or the second disc 23 may carry a resilient sealing ring ensuring complete closure of the valve when the expansion element expands.

It will be appreciated that as the second disc 23 is rigid, that part of the disc which engages the seating face 32 and thus constitutes the valve member moves in unison with the outer marginal part of the expansion element when the valve is in use.

In a modification, which is not illustrated, the first valve is omitted altogether, and a valve of the second type is alone provided.

WHAT WE CLAIM IS: 1. A valve device comprising a valve seat and a valve member with an abutment portion which is movable relative to the valve seat and co-operates with the valve seat to form a valve, and an expansion device of the kind specified, the first disc of the expansion element being flexible and resilient and comprising a circular piece of sheet metal formed with concentric corrugations, and the abutment portion of the valve member being constituted by an outer marginal part of the expansion element or by a part of the expansion element which in use moves substantially in unison with that outer marginal part, or by a part connected to the expansion element so that in use it moves substantially in unison with that outer marginal part.

2. A valve device according to Claim 1 in which both the discs of the expansion element are flexible and resilient.

3. A valve device according to Claim 1 in which only the first disc of the expansion element is flexible and resilient, the second disc thereof being rigid.

4. A valve device according to any one of the preceding Claims in which the outermost corrugation of the corrugated first disc constitutes the abutment portion.

5. A valve device according to any one of the preceding Claims in which the valve device is suitable for use with combustible gas and is incorporated in or is suitable for use in a flame-failure device, and in which the expansion element is connected to a hollow probe containing mercury, and at least one of the abutment portion and the valve seat incorporating resilient means such as to ensure complete closure of the valve when the abutment portion engages the valve seat.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. The inlet opening 14 of the valve is connected to a source of combustible gas, while the outlet opening 15 is connected to a main gas burner (not shown). A pilot burner from which the main gas burner can be lit is supplied with gas by another path. The phial 26 is so positioned as to be heated by the pilot burner. In normal use the mercury in the phial boils and some of it vapourizes, filling the phial and forcing the remaining liquid mercury from the phial into the tube 25. This in turn forces mercury from the other end of the tube into the expansion chamber. The first disc 21 is resiliently distorted in such a manner that the marginal part is lifted clear of the valve seat 13 and gas is thus permitted to pass from the inlet opening to the outlet opening and thence to the main burner.Should the gas supply be turned off or cease for some other reason the mercury cools and the valve closes, it then being impossible to restore the gas supply to the main burner without first relighting the pilot burner. In a typical construction of valve device, intended for use with natural gas or l.p. gas, the discs 21 and 23 are about one inch in diameter and the gap between the first disc 21 and the seat 13 when the valve is open is between ten and fifteen thousandths of an inch. A similar construction of valve device may be used in a thermostat, but in that case the mercury is replaced by an oil that expands when heated but does not vapourize. Also it is preferred not to use a resilient ring to provide the valve seat but to use instead the annular planar face of the valve housing. The reason for this is that the position of the valve seat is then absolutely constant; if a resilient ring were used the position of the sealing face might vary somewhat in use so that the thermostat settings would not remain constant. Although there may be a slight gas leakage when the valve is nominally closed due to the fact that closure is effected by a metal-tometal engagement, this does not normally matter as a thermostat usually employs a gas by-pass through which there is a constant flow of gas sufficient to keep the burner alight even when the thermostat valve is closed. Any slight leakage through the nominally closed thermostat valve would not significantly affect the total gas flow to the burner, most of which is by way of the by-pass. The valve device illustrated in Figure 2 is largely similar to that shown in Figure 1, and those parts of the second valve device that are similar to corresponding parts of the first valve device are given the same reference numerals. Parts of the second device that are not illustrated are similar to the corresponding parts of the first device. The device illustrated in Figure 2 includes a second valve in addition to a first valve of the kind described above. The second valve controls the flow of gas from the outer part 12 of the valve chamber to an outlet duct 30. The mouth of the outlet duct 30 is surrounded by a tubular formation 31 which projects axially into the outer part of the valve chamber and terminates in a planar annular seating face 32. In this type of device the spring 27 and boss 28 are omitted. The arrangement is such that in use when the expansion element expands the second disc 23 is brought into engagement with the seating face 32 and thus closes the second valve. In a modification either the seating face 32 or the second disc 23 may carry a resilient sealing ring ensuring complete closure of the valve when the expansion element expands. It will be appreciated that as the second disc 23 is rigid, that part of the disc which engages the seating face 32 and thus constitutes the valve member moves in unison with the outer marginal part of the expansion element when the valve is in use. In a modification, which is not illustrated, the first valve is omitted altogether, and a valve of the second type is alone provided. WHAT WE CLAIM IS:

1. A valve device comprising a valve seat and a valve member with an abutment portion which is movable relative to the valve seat and co-operates with the valve seat to form a valve, and an expansion device of the kind specified, the first disc of the expansion element being flexible and resilient and comprising a circular piece of sheet metal formed with concentric corrugations, and the abutment portion of the valve member being constituted by an outer marginal part of the expansion element or by a part of the expansion element which in use moves substantially in unison with that outer marginal part, or by a part connected to the expansion element so that in use it moves substantially in unison with that outer marginal part.

6. A valve device according to any one of

Claims 1 to 4 in which the valve device is suitable for use with combustible gas and is incorporated in or is suitable for use in a thermostat, and in which the expansion element is connected to a hollow probe containing a liquid which expands when heated, and both the abutment portion and the valve seat are rigid so that in use closure of the valve always occurs when the expansion element has contracted to the same predetermined extent.

7. A valve device according to any one of the preceding Claims in which the arrangement is such that closure of the valve occurs on contraction of the expansion element.

8. A valve device according to Claim 7 in which there is a spring which biases the expansion element towards its contracted state and thus urges the abutment portion of the valve member towards the valve seat.

9. A valve device according to any one of Claims 1 to 3 in which the arrangement is such that closure of the valve occurs on expansion of the expansion element.

10. A valve device according to Claim 9 and according to either of Claims 7 and 8 in which there are two valves, the arrangement being such that closure of one valve occurs on contraction of the expansion element and closure of the other valve occurs on expansion of the expansion element.

11. A valve device according to claim 1 and substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

12. A valve device according to Claim 1 and substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.