GB2531266A

GB2531266A - Frangible diaphragm for use in a valve mechanism

Info

Publication number: GB2531266A
Application number: GB1418081.4A
Authority: GB
Inventors: Paul David Smith
Original assignee: Kidde Graviner Ltd
Current assignee: Kidde Graviner Ltd
Priority date: 2014-10-13
Filing date: 2014-10-13
Publication date: 2016-04-20
Also published as: US20160102773A1; EP3026309B1; GB201418081D0; EP3026309A1

Abstract

A frangible diaphragm comprising ceramic discs 12, 14 for use in a valve mechanism has an actuator substance 100 such as wax provided in or on the frangible diaphragm. The actuator substance 100 expands from a smaller volume to a larger volume on application of heat, such that a force generated by the expansion causes the diaphragm to fracture.

Description

FRANGIBLE DIAPHRAGM FOR USE IN A VALVE MECHANISM

BACKGROUND

[1] A frangible diaphragm for use in a valve mechanism, and, more particularly, a singleuse valve mechanism that may be used for discharging fluid is described herein The frangible diaphragm and valve mechanism may have particular use in the field of suppressant release, such as a fire suppressant fluidS [2] The examples described herein relate to devices and methods for the controlled release o a fluid flow substance They are particularly suited, hut riot hnited, to the controlled release of a suppressing or oxtingushing agent from a cyilnder. The devices and methods described may further be used for the rapid depoyment of an extinguishing agent from a cylinder, such as those that may typica ly although not exclusively, be used on moving platforms such as aircrafts rains, military or commercial vehicles.

131 Such valves fall into two main groups; nonMermetic and hermetcally sealed, The former category is typified by the high rate discharge (HRD) valves used Qn suoprossors in mthtary dnd commercia vehhJes These can be electromectamcal or protractor fired, consrstng of either a Flapper or poppet as the main openings mechanism. Both systems contain multiple moving components arid rely on Onng seals for integnty Such va yes can be relaUvely expensive and require refurbishment prior to use.

4] Further appl catons, such as aerobpace require that the suppressor be hermetically sealed lo minimise leakage over the required environmental range end to extend service life. Such hermetically sealed extinguishers use an explosive cartridge located on the outside of an outlet disc or diaphragm, which upon actuation ruptures and releases agent into a distribution network or directly into the pttected fire zone This mothcd although very fast and rehable, is prone to fragmentation of the diaphragm during actuation and requires the use of pyrotechnic cartridges. These valves require periodic maintenance and replacement and have dssoiatcd handling, transit and s'orage restrictions [5] The examples deserted herein aim to retain the rapid opening and free flow characteristics of the prior art, whilst reducing cost, removing pyrotechnic cartridges and providing the option for hermiUcity where required.

16] DE 19736247 cisclosos a component having a body made of bnttle materiS and the use of piezoeleetno elements both embedded and laminated into the body such that, when the body is energized h the piezoelectnc elements a portion of the component is destroyed.

7] European Patent Aoplication No 14160040 discloses a ceramic disc with a pre-defined stress plane which is ractured by irnpact by a pont fcrce Means for braze attachment of the dia: means or m nirnising fragmentation eriC a means or retaining the free section of the disc after fracture are also disclosed.

[8] EP 1582789 describes cevices and methods for controffirig the r&ease of a substance wh oh are pwticularly suited to the control of substances such as fit extinguishing media, The devices and methods described comprise a housing having ar inlet for connection to a source of a substance and an outlet, with a passage extending therebeveen. The passage may be closed by a frangible elemont wnich comprises a ceramtc dir that s connected to a source of electrical current. The disc may be a metal oxide ceramic dsc, and may be fractured by an electrical pulse which is applied to the diso

SUMMARY OF THE INVENTION

[9] I-one examøle, there is provided a trangiole diaphragm for use r a valve mechanism, said frangible diaphragm comprising an actuator substance provided in, or on, the frangible diaphragm, wherein the actuator substance expands from a smaller volume to a larger volume on application of heat such that a force generated by the expansion causes the diaphragm to fracture.

[10] In one example, the actuator substance may be wax. The wax may be petroleum based or the wax may be a synthetic wax.

[11] Further the frangible diaphragm may comprise a heating element or heating the actuator substance. The heating element may be formed from a coil of resistance wire provided on, or in, the actuator substance.

[12] Further, the frangible thaphragm may cononse one or more discs and the actuator substance may be provided in, or on, at east one of the one or more discs such that, when activaed, the actuatr suostance casos at east one of the one or more discs to fracture, The actuator substance may be located adjacent an outer edge of at least one ot the one or more dscs [13] The frangible diaphragm may further comprise means for rig thy attaching the one or more discs to each other. The means for rigidly attaching the one or more discs to each other may comprise a locking ring that is configured to be attached to a holder surrounding the one or more discs.

[14] In another example, there is provided a valve mechansm comprising a valve body having an inlet port and an outiet port and a passageway extending therebetween and a frangible diaphragm as described above, wherein the diaphragm is held within the v&ve body such that the diaphragm blocks the passageway when the diaphragm is intact, and wherein when the actuator suostance is activated, the diaphragm fractures such that fluid car flow from tho inlet poit to the outlet port.

BRIEF DESCRIPTION OF THE DRAWINGS

[151 Figure 1 shows a view of a frangible diaphragm [161 Figure 2 shows a view of section A-A of Figure 1, [17J Figure 3 shows a detail view of section B of Figure 2, (181 Figure 4 shows a view of the frang ble diaphragm of Figure I [19] Figure 5 shows a view of an alternative frangible diaphragm.

[20] Figure 6 shows a valve mechanism with the frangible diaphragm of Figure 1.

DETAILED DESCRIPTION

[21] Figures 1 and 2 show a frangible diaphragm 10 for use in a valve mechanism is shown. In general, the frangible diaphragm 10 is provided between an inlet port and an outlet port of a valve mechanism (described later). The frangible diaphragm prevents fluid from flowing through the conduit, until it is activated, by forming a seal across the valve between the inlet arid outlet pod Wnon the frangnle diaphragm L activated the seal s broken so that fluid can flow through tie conduit from the nle: P01 to the outlet port of the valve mechanism [22] Generally, there is provdec an actuator in the frang No diaphragm thai expands when hedted T no actuator may be embedded n or formec on, the 13 frangiole diaphragm When the actuator is heated, the expansion of the actuator S constrained hus ciaating a tote causing the diphragm to Dreak The seal provided by the diaphragm is therefore broken so that fluid can flow between the inlet port and outlet port of the valve mechanism.

[23] The actuator ir the frangible diaphragm 10 may be an actua'or substance,

for example, wax.

[241 An example of a frangible diaphragm is shown in Figures 1-4. The frangible diaphragm 10 may be in the form of a disc, and in this example comprises a first disc 12 and a second disc 14 In the example where two discs are shown, the two discs allow for a lower force or smaller element to fracture the discs. The fluid pressure within the vaive mechanism, against the discs, can cause one, or both, of the discs to fracture. First disc 12 and second disc 14 have an upper surface and a lower surfaco The first disc 12 ard second disc 1'l provide before activation, a seal that prevents fluid from moving from an upper conduit 17 to a lower conduit 16. As described later, the upper conduit 17 is in flow communication with an inlet port of the valve mechanism and the lower conduit 16 is in flow communication with an outlet port of the valve mechanism. The first disc 12 and second disc 14 may be formed from a brittle ceramic matedal, for example alumina, but may also be formed from any simfiarly frangible, for example, brittle vitreous or polymeric material, F25) As shown in Figure. 2, ri one example, the upper surface of the second disc 14 is adjacent the lower surface of the first disc 12. The two discs 12 and 14 act as a seal to prevent fluid from flowing through me conduits 16 and 17. In order to rnamtan tie posmon of the discs 12 and 14, a moans for ngidly attachng the second disc 14 to the first disc 12 is included in the frangible diaphragm, In the example shown in Fgure 2, the means for rigidly attachng the second disc 14 to the first disc 12 is a holder 11 that includes a screw thread to receive a locking ring 15. The dIscs 12 and 14 are placed in the holder 11 and the locking ring ISis then screw threaded into the holder 11. A flanged portion 20 acts as a stop within the bolder 11 such that the discs 12 and 14 are held in position r the heWer 11 When the locking ring 15 is screw tireaged nto the holder 11 the second disc 14 and the first disc 2 are rigidly attached so as to prevent relaive movurncnt of the discs 12 and 14. In one example, the holder is metal, but the holder may also be formed from other suitable materials. Other means for rigidly attaching the discs 12 and 14 together could be used. for example by inducton brazing to form a joint between the discs 12 and 14 around their outer thameter. Another example may be to use an adhesive/epoxy bonding on the lcwer surface of the first disc 12 ard on the' upper surface of the second disc 14.

26] A hermetic seal may be pray dad between the holder 11 and the firstdisc 12 one example, the holder 11 may be braze attached to the first disc 12 For example a heimefic seal may be pr wided throLgh braze attachment of, for eAample a low expansion alloy (is, Kovar Ttvl) flango to both the tirs disc 12 and the holder 11 [271 The frangible diaphragm has a disc-shaped surface when forming a seal ri a cylindrical valve conduit, hut can of course be appropriately shaped to seal any conduit. As an example, the frangible diaphragm 10 of Figures 1-4 is shown to be cyhndnca The discs 12 and 14, and locking nng 15 ae dlso shown to be cylindrical. However, these components of the frangible diaphragm 10 may be any other suitable shape.

[28] To break the seal, force is applied from within the diaphragm to fracture the diaphragm As mentioned abo'4e, the force comes from an actuator that may be embedded in or formed on the frangible diaphragm to cause the diaphragm to fracture. In the two disc embothment shown in Figures 2 and 3, for example, the actuator could be embedded in or formed on one of the discs causing that disc to rupture, with the other disc fracturing due to stresses applied to it from the fracture of the disc containing the actuator.

[29] As shown in Figures 2 and 3, the second disc 14 includes means 100 tor applying a force to the second disc 14. The means for applying a force, when activatec causes the second disc 14 o fracture lie first disc 12 then fractures due to iho increased stress appl ed as a result of the other cisc fracturing, for e>ample, from tne fluid in the upper fluid conduit 17 to allow flwd to flow through both the upper conduit 17 to the lower conduit 16 (Le,, from an inLet port to an outlet port of Inc valve rnecnanism) In the example shown ii FigLrc 2, the means 100 fr applyinq a force to the diaphragm includes ar actuator substance 102 capable of expansion. In this particular example, the actuator substance is embedded in or located in a void (not shown) in the second disc 14. In other examples, the actuator substance could be in the first disc 12 or both discs 12 and 14 or the diaphragm may comprise only a single disc or more than two discs.

[30] For activation, some means are provided to heat the actuator substance. In this exampic, a heating element 103 s attached to or embedded i' the actuator substance The heatuig element 103 is connected to, for example, an electrical Dower supply such that heat can be apphed o tie wax actuator 102 In some examples, the electrical power supply could be a constant current power supply or a current I mited DC power supply The ieat from the heating element 103 causes he ccii ato substante 10$ to expand Ln one example, the expansion of the actuator substance 102 occurs due to a change of rate of the actuator substance when applied with heat. For example, the actuator substance 102 couid move from a sohd state to a liquid state, when heated In an example, the hcating element 103 may be formed from a coF of resistance wire. As an example, where the actuator substance is 5mm in diameter and 1mm long, 12 J would be requifed to bring the actuator substance to a melting temperature, for example 100 Celsius.

i] As the actuator substance 102 expands. It devers stress to the disc in wmch t s rovded here the second dEac 14, for example Ths exet a force on to the second disc 14 such that the second disc 14 fractures, In some examples the actuator substance 102 expands by between I 0%-20%. As the actuator substance 102 is constrained by its location In the disc here, being provided in a void in the second disc 14, it is unable to expand and so a stress is applied to the second thsc 14 As an example, ths may be a force ci between 200MPa ard 400MPa. The stress applied to the second disc 14 causes the secQnd disc 14 to fracture, In the examples shown, the wax actuator 102 and heating element 103 are located adjacen L ie outer edge of the second disc 14 to ensure that the fracture prooagates around thc circumference of the dsc to form a clear open aperture.

1321 1 he surfaces of the first and second cisc 12 and 14 may be suthcently smooth sc as to orovide a quic hght sea t pmoent leaicage of the actuator substance 102 when, for example, it is in a liquid state. Alternatively, an additional seal may be positioned between the first disc 12 and the second disc 14 to prevent leakage of the actuator substance 102 For example, a tin motaffic (a g coppery fIm may be incorporated between the first disc 12 and the second disc 14.

[33] In the example shown in Figures 2 and 3, the actuator substance 102 and the heating element 103 are connected to an electrical power supply by leads 101.

The leads 101 extend through tho second to 14 and through the lower conduit 16 to an electric& power supply (not shown) A hqtnd tight seal may be Ic"med oetween the leads 101 and the second to 14 Ths hquc tight seat may be formed by a suitable metal to ceramic bond, for example, braze attachment or a suitable ceramic epoxy.

[34] As mentioned above, when the actuator substance 102 is heated, the disc in which Is embedded -here, the second disc 14. fractures. The fluid contained in the upper conduit 17 is in fluid communication with the first disc 12. This applies additional stress to the first disc 12. The first disc 12 is fractured from the pressure applied to the upper surface of the first disc 12 by the fluid contained in the upper conduit 17 Ab the first dcc 12 iratures this allows for fluid communication between the upper conduit 17 and lower conduit 16, thereby allowing the extinguishing fluid to flow from the inlet port to the outlet port of the v&ve mechanism.

[35] The first disc 12 may be made of a weaker material than the second disc 14 making it break under the pressure of the fluid once the second disc 14 has been broken. Aitematively, both discs could be made of the same material but break under the lorce of the fluid wien the overa thickness has been reduced by breakage of the second disc 14.

[36] The fact that the discs, 12 and 14, are constrained together, for example by holcor 11 also means that the force that fractures the second disc It wifi act to some extent on the first disc 12.

[37] The actuator substance 102 may be a wax, but other suitable materials may also be used. For example, the actuator substance 102 coud be a petroleum based wax (e.g. paraffin or microcrystalline), a synthetic polymer wax e.g. ethylenic polymers, chlorinated naphthalenes), natural animal or vegetable wax (e.g. beeswax, carnauba).

[38] Although a twc-disc arrangement has been ooscribed, it is envisaged thdt one disc or more than two discs could he provided to form a seal between an rlet oort and outlet port One or more discs may have a actuwor substance, as described above, to acture one or more d sos 2% [29] Figure 5 shows an alternative to the arrangement shown ir Figures 2 and 3 In this example the frangible diaphragm 10 compnses three discs 212 213 and 214. The three discs 212, 213 and 214 each have an upper and a lower surface.

The first disc 212, second disc 213 and third disc 214 provide, before activation, a seal that p-events fluid from movng from an upper conduit 217 to a lower conduit 216, The upper surFace of the fret disc 212 is n fluid communication with the fluid contained in the upper conduit 217 and tne third disc is in fluiø commurication with the lower conduit 21$.

[30] As with the example shown 4n Figuios 2 and 3, the first disc 212, second disc 213 and third disc 214 can be rigidly attached by a holder Ii, as described above. The holder Ii, arid locking ring 15 rigkily attach the discs 212, 213 and 214 to prevent r&ative movement of the discs 212, 213 and 214, Other means for rigidly attaching the discs 212, 23 anc 24 could be used as described accve [31] As above, the frangible diaphragm has a disc-shaped surface when forming a seal in a cylindrical valve conduit, but, of course, can be appropriately shaped to seal any conduit.

[32] In the example shown in Fgure 5 the second disc 213 and tnird disc 214 indude means 201 and 202 for applying a force to the second dcc 213 and third disc 21, -espectively the means 201 and 202 far applying a Force, when activatea can cause the secona cisc 213 and third disc 214 to Fracture The first disc 212 thai fractures cue to the force dpphe as a result of the other discs fracturing, for example, from the fluid in the upper conduit 21 7. As with the example shown in Figures 2 and 3, the means 201 and 202 for applying a force to the second disc 213 and third disc 214 includes an actuator substance, As can be seen in Figure 5, the actuator substance 202 is embedded in, or located in, a void in the second disc 213 and the actuator substance 201 is embedded in, or located in, a void in the third disc 214.

[33] For activation, some means are provided to heat the actuator substances 201 and 202 as debcibed above n relation to Fig.res 2 and 3 Who-heat is provided, the actuaor substances expand and deUver stress to the ciscs ii wnch they are provided -here, the second disc 213 and th rd disc 214 This exei'ts a force on the second disc 213 and "iud disc 214 such that the second cisc 213 and third disc 214 fracture in a simar way to the two4isc arranqement described above in relation to Figures 2 and 3. This allows for the first disc 212 to fracture train pressure appUed by the fluid contained in the upper conduit 217. Of course, an actuator substance could also be present in the first disc 212 of the frangible diaphragm, or could only be present in one of the discs 212, 213 or 214.

[34] As above, the first disc 212 may be made of a weaker material than the second and third discs 213 and 214 making ii. break inder tho pressre ci the fluid once the second and third discs 213 and 214 have been broken Al*ernatiVely, all three discs could be made of the same material but break under the force of the fluid when the overafi thickness has been reduced by breakage of the second and thfrd discs 213 and 214.

[35] A valve mechanism 500 including the frangible diaphragm 10 is shown n Figure 6 The valve mechanism 500 includes a valve body having an intel port 52 and an outet port 64, and a passageway 56 extendIng therebetween, The frangible diaphngm 13 is positionoc in the valve mechanism 600 to provide a seal between the inlet port 52 and the outlet port 54 The upper condut 17 of the frangible diaphragm 10 as shon in Figures 14) is in fluid communication with the inlet port 52 The tower conduit 16 of the ang bie dIaphragm 10 is in %id communication with the outlet port t54 When the kangrbte diapiragn is act va*ed as thscussed above, the seal is broken to provide a fluid flow from the inlet port 52, through the lower and upper coriduts of the frangible diaphragm, to the outlet port 54 for deployment of an extinguishing agent.

[36] The valve mechanism 500 described above is therefore a sngle-use, or repairable, valve mechanism that provides significant advantages over previous valve mechanisms, as, when operated, it is able to create a clear opening between the inlet port 52 and the outlet port 54 of the valve due to the fact that the frangible diaphragm IC prov des a clear open aperture using an actuator substance 102 [37] This valve mechanism also aflowb for the minimisation of tne number o components and the complexity of the valve design thereby reducirg cost of the valve mechan sm It further retains the rapid opening and Ire 1kw char?ctenstics ol known devices and methods, Nhilst removing the neca for pyrotechnic cartridges and providing the option for hermiUcity where required.

Claims

ULAIMS1 A frangible diaphragm. for use fri a valve mechanism, said frangible diaphragm comprising: an actuator substance provided in, or on, the frangible diaphragm, wherein the actuator substance expands from a smaller volume to a larger akime on application of heat such that a force generated by the expansion causes the diaphragm to fracture.
2 The frangib a diaphragm of claim I wherein the actuator substance is wax 3 The frangib a diaphragm of claim 2 wherein the waA is petroleum baseJ 4. The frangible diaphragm of claim 2 wherein the wax is a synthetic wax, 5. The frangible diaphragm of any preceding claim, wherein the frangible diaphragm further comprises: a heating element for heating the actuator substance.6 The fta'giblo d aphragm of claim 4, wherein the heating element is farmed from a cell of resistance wire provided on, or n. the actuator substance.7. The frangible diaphragm of any preceding claim, wherein the frangible diaphragm further comprises: one or more discs; and wherein the actuator substance is provided in, or on, at least one of the one or more discs such that, when activated, the actuator substance causes at least one of the one or more discs to fracture.8. The frangible diaphragm of claim 7 wherein the actuator substance is locatoc adiacent an outer edge o at least one of tie one or more discs 9 The frangible d aphragrn of c aims 7 and 8, thither comprising means for rigidly attaching the one or more discs to each other.10. The Frangible diaphragm of claim 9 wherein the means for rigidly attaching the one or more discs to each other comprises a locking ring that is configured to be attached to a holder surroundThg the one or more discs.11. A valve mechanism comprising: a valve body having an inlet port and an outlet port and a passageway extending therebetween; and a frargthle thapiragm as cla!med n any precedmg clan wheren the diaphragm s held within the valve body such that the diaphragm btocks the passageway when the daphragm a ntact, and wherein, when the actLator substanGe a actwated, the d aphragm fractures such that flud can flow from the iriet port to the outlet port.