GB2308424A

GB2308424A - Pressure control valve

Info

Publication number: GB2308424A
Application number: GB9525961A
Authority: GB
Inventors: David Edmund Talbot Garman; Richard Edmond Fletcher
Original assignee: Mangar International Ltd
Current assignee: Mangar International Ltd
Priority date: 1995-12-19
Filing date: 1995-12-19
Publication date: 1997-06-25
Anticipated expiration: 2015-12-19
Also published as: GB2308424B; GB9525961D0

Abstract

A pressure control valve 10 comprises a hollow body 12, a valve seating 41 within the hollow body between an inlet passage 24 and a control space 23 in the hollow body. An outlet 25 leads from the control space 23. Pressure sensitive means 31, (32 figure 7) are located in the control space to move a valve member 38 to and from a valve closed position in which the valve member engages the seating 41. The valve member 38 and pressure sensitive means 31, (32) are provided by portions of a moulded device 13. The pressure at which the valve closes may be adjusted by applying a control pressure to port 26. Alternatively the pressure may be adjusted by adjusting the axial position of an insert 14 which carries seating 41. A spring (17, figure 4) may be provided to provide sudden rather than progressive closing of the valve.

Description

PRESSURE CONTROL VALVE Pressure control valves for air systems are known in which the pressure is limited by venting the excess to atmosphere by opening the valve against a bias provided by a spring. Such venting pressure control valves give rise to problems in that they are wasteful of energy and, if the valve becomes faulty, the pressure can be allowed to drop below the required pressure.

A possible alternative to using a venting pressure control valve is to use a pressure regulator. Such regulators generally comprise a diaphragm which moves a valve member to close a valve opening when the pressure at the gas output side of the diaphragm reaches a predetermined maximum. However such pressure regulators give rise to problems of expense, bulk (size and weight) and susceptibility to malfunction caused by wear or contamination.

An object of the invention is to enable the aforementioned problems to be reduced or avoided.

According to the present invention there is provided a pressure control valve comprising a hollow body, a valve seating within the hollow body between an inlet passage and a control space in the hollow body, an outlet leading from the control space, and pressure sensitive means in the control space to move a valve member to and from a valve closed position in which the valve member engages the seating; and characterised in that the valve member and pressure sensitive means are provided by portions of a moulded device.

In preferred embodiments, the moulded device is secured to the body so as to sub-device the control space and provide therein a control chamber which is pneumatically separate from the remainder of the control space.

The moulded device is preferably of a single elastomeric material, but may be moulded to incorporate one or more inserts of a different material or materials, or may be a co-moulding of a plurality of materials. The preferred elastomeric material is a synthetic rubber which is durable, resistant to oxidation and degradation by air pump lubricants, carbonic acid and salt water.

The present invention further provides a pressure control valve comprising a hollow body, a valve seating within the hollow body between an inlet passage and a control space in the hollow body, and pressure sensitive means in the control space to move a valve member to and from a valve closed position in which the valve member engages the seating; and characterised in that the pressure sensitive means comprises a major diaphragm and a minor diaphragm moulded to extend from opposite end portions of a hollow core having the valve member at one end. The valve member is preferably integral with the core.

The valve seating is preferably positionally adjustable or presettable within the hollow body to permit adjustment or presetting of the pressure at which the valve closes.

The valve seating may be provided on a non-return valve.

The body preferably comprises parts connected together to locate part of the moulded device, e.g. the periphery of the major diaphragm, in a predetermined position in the control space.

The invention further provides a pressure control valve comprising a hollow body, a valve seating within the hollow body between an inlet passage and a control space in the hollow body, and pressure sensitive means in the control space to move a valve member to and from a valve closed position in which the valve member engages the seating; and characterised in that the pressure sensitive means comprises a major diaphragm and a minor diaphragm which extend from and support a hollow core on which the valve member is formed, the minor diaphragm being doubled back upon itself to provide a rolling hinge to allow the hollow core to move axially within a variable length cylinder formed by an outer portion of the minor diaphragm.

A supplementary bias spring may act on the major diaphragm.

The portion of the control space between the two diaphragms, or the control chamber, is preferably vented to atmosphere, but may be precharged to a predetermined pressure or subjected to a controlled pressure.

The invention will be described further, by way of example, with reference to the accompanying diagrammatic drawings, wherein FIGURES 1 and 2 show a first embodiment of pressure control valve of the invention in longitudinal cross-section with the valve in an open condition, and in a closed condition, respectively; FIGURE 3 shows a modified form of the valve shown in FIGURE 1; FIGURES 4 and 5 show a second embodiment of the valve in open and closed conditions respectively; FIGURE 6 shows a modified form of the valve shown in FIGURE 5; FIGURE 7 shows a moulding employed in the above valves, in cross-section and in an "as moulded" condition; FIGURE 8 shows an end view of an insert providing a valve seating and a mounting and seat for a non-return valve employed in the valves shown in FIGURES 1 to 5; and FIGURES 9 and 10 show a supplementary spring, in plan and side elevation respectively, employed in the valve shown in FIGURES 4 to 6.

In the first embodiment, the pressure control valve 10 primarily comprises a body 12 containing a moulded device 13 and an insert 14. The body 12 comprises an inlet end moulding 20 and an outlet end moulding 21 secured together at a junction 22 around a control space 23 defined in the body 12 between an inlet 24 and an outlet 25. A control chamber 23A in the control space is vented to atmosphere via a port 26 in the body. The axially extending body surfaces at the junction 22 are preferably joined by bonding, e.g. by an adhesive, but may be screw threaded so that the mouldings 20 and 21 are releasably connected.

The inlet end moulding 20 has an inlet extension 27 attached thereto, which extension 27 is formed to be part of a quick release socket mechanism 15 to receive a pneumatic supply plug (not shown) of known form. The axially extending surfaces of the junction between the moulding 20 and the extension 27 are bonded together but may be screw threaded.

The outlet end moulding 21 provides a spigot 28 to receive a push-on delivery tube (not shown).

The moulded device 13 is moulded from a resilient elastomeric material such as rubber to the shape shown in FIGURE 7 so as to comprise a thick walled hollow core 30, a major diaphragm 31 at the outlet end of the core, and a thin walled conically tapered portion 32 at the other end of the core. This conically tapered portion 32 has an inwardly directed annular rim 33 at its free end.

The portion 32 is folded back upon itself before it is put into the body moulding 20 to constitute a minor diaphragm 35 which incorporates a rolling hinge 34 connecting an outer cylindrical portion with the remainder of the diaphragm lying within the outer portion; and the rim 33 is everted to serve as a stiff terminal collar 36 which is a tight push-fit in a stepped recess in the moulding 20. The collar 36 may be bonded into this recess.

The major diaphragm 31 has a peripheral flange which is trapped between the mouldings 20 and 21. As shown in the drawings, the core and diaphragms cooperate with the body to define the control chamber 23A and to pneumatically separate that chamber from the rest of the control space and the inlet.

At the junction of the core 30 and the diaphragm 35.

an end face 38 of the core 30 serves as a valve member as hereinafter described.

The insert 14 (shown also in FIGURE 8) is a hard plastics moulding having a cylindrical body 40 one end of which provides a valve seating 41. Radial arms 42 project outwardly from the body 40 to engage the inlet end moulding 20 to locate the insert in the moulding between the device 13 and the inlet 24. In this embodiment the insert forms part of a non-return valve 16 and includes radial arms 43 which project inwardly from the body 40 to locate a cylindrical socket 44 within the body. A stem 45 of a flexible plastics valve member 46 is located in the socket 44 to hold a head 47 in a position to engage the other end 48 of the body 40 and thus block that end of the passage 49 defined within the body 40.

In use, the moulded device 13 serves as an integrated pressure sensitive actuator, valve member and low resistance guide means for the valve member. In the normal condition the valve is held open by the major diaphragm 31 assuming its natural or as-moulded configuration. When gas under pressure is supplied to the inlet 24 it will flow around the insert 14, through the device 13 and out of the outlet 25 until the pressure at the outlet rises to a level at which the force exerted on the outlet side of the major diaphragm becomes sufficient to stretch and deflect that diaphragm to move the core 30 towards the inlet 24 until the valve member (end face 38) abuts the seating 41 to close the valve as shown in FIGURE 2. During this movement, the minor diaphragm 35 is not significantly stretched, but instead the rolling-hinge 34 becomes displaced as the axial length of the outer portion 39 increases and, in proportion thereto, the axial length of the remainder decreases.

When pressure is removed from the inlet 24, the nonreturn valve 16 opens to permit gas to flow through the outlet, the core and the cylindrical body to the inlet.

During opening of the valve 16 the head 47 is flexed resiliently to lift off the end 48. This enables the gas pressure in the outlet 25 to be vented, thus causing the valve 38 to become unseated, and thereby re-setting the valve to its unpressurised state.

Without changing the components, the pressure at which the valve moves to the closed position can be varied by applying a control pressure to the port 26.

Another way of varying said pressure is by adjusting the axial position of the insert 14 and such adjustability may be provided in many ways. For example, and referring to FIGURE 3, the outer ends of the arms 42 may be toothed to engage a female threaded portion 50 of the moulding 20.

The position of the insert may be changed by inserting a tool through the outlet 25, the core 30 and into the insert to engage between the arms 43 so that the insert can be rotated by rotating the tool.

Instead of a quick release mechanism 15 or a spigot 28 (at either or both of the inlet and outlet ends of the body 12), the body 12 may be provided at either or both ends with threaded connections to receive threaded pipefittings, e.g. as shown in FIGURE 3 in which the moulding 21 has an internally threaded socket 51 and a modified form of the inlet extension 27 provides an internally threaded socket 52.

The second embodiment (FIGURES 4 and 5) is similar to the first embodiment except primarily in that the functional characteristics of the valve are modified by a supplementary bias spring 17 (shown also in FIGURES 9 and 10).

The spring 17 is preferably of stainless steel and comprises a rim 53 from which fingers 54 project inwards towards a central aperture 55. The spring 17 is pressed to dished or shallow conical form so that the dishing will reverse suddenly when sufficient axially directed force is applied to overcome the inherent resilient resistance provided by the spring, and will return to its original condition when said force is removed.

The rim 53 of the spring is clamped between the periphery of the major diaphragm 31 and the inlet end moulding 21 so that the fingers 54 displace the major diaphragm, and thus core and valve member, towards the outlet when the valve is in an unpressurised state as shown in FIGURE 4.

In use, when the pressure at the outlet rises the core at first moves only slightly towards the inlet as the portion of the major diaphragm unsupported by the fingers flexes, upon further increase the fingers also flex allowing further movement of the core until such time as the resistance provided by the spring reaches a maximum and the dishing of the spring changes suddenly to reduce said resistance substantially allowing the diaphragm and core to move rapidly through a substantial distance to slam the valve member against the valve seating. Thus, instead of closing progressively (as in the first embodiment), the valve of the second embodiment remains substantially fully open until the predetermined outlet pressure is reached whereupon it closes suddenly to the condition shown in FIGURE 5.

In the foregoing embodiments, if the non-return valve 16 is not required for depressurisation of the outlet, the insert 14 may be replaced by a modified form in which the cylindrical body 41 is of solid cylindrical form, for example the body 41A shown in FIGURE 6. Depressurisation can be achieved by other means, e.g. applying a higher pressure to or inserting a push rod through the port to thrust the major diaphragm towards the outlet.

Recesses 57 may be formed in either or both ends of the body 41A for engagement by a tool inserted through the inlet or outlet for adjustment of the axial position of the insert 14, or alternatively the body 41A may have an axial extension which projects out of the inlet, as shown in broken lines, so as to be accessible for manual adjustment when the supply connector is removed.

The invention is not confined to details of the foregoing examples, and the invention includes and provides a valve having any novel part, functional feature, arrangement of parts or combination of parts and features disclosed herein or in the accompanying drawings. The terms and expressions used herein are by way of example and are to be taken to include generics, synonyms and functional equivalents. For example, the "rolling-hinge" could be called a "movable reflex-fold zone" or a "movable folded bearing portion" because this hinge, zone or portion provides very low friction support and guidance for the device in the narrow end of the control space, as well as being resistant to being impeded by contamination or particles entering the valve.

In the event of the minor diaphragm failing, the valve member and the residually attached portion or portions of that diaphragm will serve as a piston in said narrow end to permit the valve to maintain most of its effectiveness whilst minimising leakage of the gas supplied into the control chamber, i.e. the vented portion of the control space. To enhance this safety feature, the valve member preferably has a diameter which is enlarged to be substantially greater than that of the valve seating and be only slightly less than the diameter of said narrow end.

The positioning of attachment of the diaphragm to the core may be varied to suit the configuration of the control space and the positioning of the seating.

Claims

1. A pressure control valve comprising a hollow body, a valve seating within the hollow body between an inlet passage and a control space in the hollow body, an outlet leading from the control space, and pressure sensitive means in the control space to move a valve member to and from a valve closed position in which the valve member engages the seating; and characterised in that the valve member and pressure sensitive means are provided by portions of a moulded device.

2. A pressure control valve comprising a hollow body, a valve seating within the hollow body between an inlet passage and a control space in the hollow body, and pressure sensitive means in the control space to move a valve member to and from a valve closed position in which the valve member engages the seating; and characterised in that the pressure sensitive means comprises a major diaphragm and a minor diaphragm moulded to extend from opposite end portions of a hollow core having the valve member at one end.

3. A pressure control valve comprising a hollow body, a valve seating within the hollow body between an inlet passage and a control space in the hollow body, and pressure sensitive means in the control space to move a valve member to and from a valve closed position in which the valve member engages the seating; and characterised in that the pressure sensitive means comprises a major diaphragm and a minor diaphragm which extend from and support a hollow core on which the valve member is formed, the minor diaphragm being doubled back upon itself to provide a rolling hinge to allow the hollow core to move axially within a variable length cylinder formed by an outer portion of the minor diaphragm.

4. A valve as claimed in Claim 1, 2 or 3 wherein the moulded device or pressure sensitive means is secured to the body so as to sub-divide the control space and provide therein a control chamber which is pneumatically separate from the remainder of the control space.

5. A valve as claimed in Claim 1, 2, 3 or 4 wherein the valve seating is positionally adjustable or presettable within the hollow body to permit adjustment or presetting of the pressure at which the valve closes.

6. A valve as claimed in Claim 1, 2, 3, 4 or 5 the valve seating is provided on a non-return valve.

7. A valve as claimed in any one of the preceding claims wherein the body comprises parts connected together to locate part of the moulded device or pressure sensitive means in a predetermined position in the control space.

8. A valve as claimed in Claim 2 or 3 or any one of the preceding claims as applied thereto, wherein a supplementary bias spring acts on the major diaphragm.

9. A valve substantially as hereinbefore described with reference to Figs. 1 and 2, Fig. 3, Figs. 4 and 5, Fig. 6, or any thereof as modified by any of Figs. 7 to 10, of the accompanying drawings.

9. A valve as claimed in Claim 8 wherein the portion of the control space between the two diaphragms, or the control chamber, is vented to atmosphere.