RADIATION ACTUATED VALVE

Abstract: A valve (1) is provided having a body with a flow path (5) therethrough. A membrane prevents fluid flow through the flow path. Radiation means, in one embodiment, a heat providing element (6) abuts the membrane and is operable to weaken or destroy at least part thereof.

Description: Radiation actuated valve FIELD OF THE INVENTION This invention relates to a valve, more particularly, but not exclusively, to a valve for controlling the release of fluid under pressure. BACKGROUND TO THE INVENTION The flow of fluids is almost invariably controlled by valves. While many valves allow the rate of fluid flow to be controlled, it is often not necessary for valves to be capable of this. For example, where it is desired to quickly release fluid under pressure, it suffices to have a valve which merely prevents flow or permits flow. Apart from "bursting disc" type valves which permit flow once pressure exceeds a maximum, the applicant knows of no other valve which can be selectively opened without the need for moving parts which add to the expense of valves and effect the reliability thereof. The latter two considerations are frequently of great importance when selecting valves. OBJECT OF THE INVENTION It is the object of this invention to provide a valve which is easily manufactured and can be reliable operated. SUMMARY OF THE INVENTION In accordance with this invention there is provided a valve comprising a body with a flow path therethrough, a membrane associated with the flow path to prevent fluid flow therethrough, and radiation means located adjacent at least part of the membrane and selectively operable to irradiate the membrane to cause weakening or destruction of at least a part thereof. Further features of the invention provide for the radiation means to provide heat; for the radiation means to be a resistive element; for the body to be in the form of a board with at least one orifice therethrough defining the flow path; and for the resistive element to extend at least partially around the circumference of the at least one orifice. Still further features of the invention provide for the membrane to be made of a plastics material; for the membrane to be adhesively secured to the body over one end of the flow path; for the membrane to be formed from a number of layers of a material; and for the membrane to be operatively melted by the radiation means. Yet further features of the invention provide for the body to be securable to a reservoir with the flow path adjacent an outlet from the reservoir; for the radiation means to be connected through a switch to electricity supply means; for the electricity supply means to be a battery or mains supply; and for the body to be a circuit board with the resistive element printed thereon; alternatively for the resistive element to be printed on the membrane; further alternatively to be captured within the membrane. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described, by way of example only, with reference to the drawings in which: Figure 1 is an oblique view of a first embodiment of a valve; Figure 2 is a sectional side elevation of the valve in Figure 1 ; Figure 3 is a part sectional side elevation of the valve in Figure 1 in use on a reservoir; Figure 4 is an oblique view of a second embodiment of a valve; Figure 5 is an oblique exploded view of a third embodiment of a valve; Figure 6 is an oblique view of a fourth embodiment of a valve; and Figure 7 is an oblique view of a trunk with a pressurised container located therein. DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS A valve (1) is shown in Figures 1 and 2 and includes a board-like body (2) having a top surface (3) and a bottom surface (4) and a central orifice (5) extending between the surfaces (3,4). In this embodiment, the body (2) is made from material used to construct electronic circuit boards. A resistive element (6) is printed on the body (2) to extend part way about the circumference of the orifice (5) from contact points (7) near a side (8) of the body (2). A membrane (10) made from a plastics material is adhesively secured to the body (2) over the orifice (5) and resistive element (6). Electrical wiring (11) is soldered to the contact points (7) to connect the resistive elements (6) with a battery (12) and a normally open in-line switch (13). In use, the switch (13) is closed causing an electrical current to flow through the resistive element (6) to produce heat. The heat produced due to the short circuit melts that part of the membrane (10) abutting the resistive element (6). Where the membrane (10) is subjected to pressure in the direction of the orifice (5), the melting thereof allows the pressure to rupture the membrane. Referring to Figure 3, the body (2) can be secured between flanges (20) over the outlet (21) of a reservoir (22) filled with a fluid (23) under pressure. The body (2) will be secured with the top side (3) carrying the membrane (10) facing into the reservoir (22). The membrane (10) is selected to withstand the pressure of the fluid thereon and so prevent fluid flow through the outlet (21) and orifice (5). Clearly, the material used in the membrane (10) will also be selected ' to resist corrosion that could possibly be caused by the fluid (23). It has been found that the material sold under the brand name "Mylar" and which is supplied with an adhesive backing provides excellent resistance to a wide range of fluids and to deformation by pressure, but any suitable material can be used. When it is desired to release the fluid (23) in the reservoir (22), the switch (13) is closed causing the membrane (10) to melt as described above, allowing the fluid (23) to escape through the outlet (21 ) and orifice (5). A simple yet highly reliable and cost effective valve is thus provided which can be constructed to suit many different requirements. Although the valve of the invention can only be used once, it can easily be replaced without incurring significant costs. It will be appreciated, however, that many other embodiments of a valve exist which fall within the scope of the invention, especially as regards the configuration and materials of construction thereof. For example, a valve (40) could include a board-like body (41) with an elongate aperture (42) therethrough covered by a suitably shaped membrane (43) and having a resistive element (44) extending across the orifice (42) as shown in Figure 4. In this embodiment, the resistive element will be a length of resistive wire. Also, where large fluid flow rates are required, a number of apertures can be formed in a valve body rather than a single large aperture. This helps reduce distortion of the membrane caused by pressure. Alternatively, as shown in Figure 5, the membrane (50) can have two layers (51) with a resistive element (52) interposed between the layers (51). As further shown, the membrane (50) is secured to a cylindrical valve body (55) by a radially inwardly extending flange (56) at the end of a sleeve (57), the body (55) and sleeve (57) being complimentary threaded (58) for engagement of the sleeve (57) over the body (55). An aperture (59) in the flange (56) receives a connecting wire (60) from the resistive element (52). The use of layers has been found to be particularly useful where the material used for the membrane tends to exhibit non-uniform strength characteristics. Any suitable material can be used and the thickness of the material used will depend on the application. For example, the membrane can be in the form of a thick disc of plastics material with a resistive element moulded therein. It will further be appreciated that many other embodiments exist which fall within the scope of the invention as regards the radiation means. Thus, where it is not desirable to use heat to weaken or destruct the membrane, light could be used. In this instance it is envisaged that a light emitting diode or other suitable source of light could be located adjacent a membrane made from light sensitive material. It is further envisaged that radiation such as gamma radiation could even be used to weaken or destruct a membrane. In this instance the radiation source and valve body would be of suitably robust construction and not be intended for disposal, whereas the membrane would be easily replaceable after destruction. Referring to Figure 6, it is also envisaged that a resistive element (70) can be printed on a membrane (71) of a suitable material, for example the material used for dot matrix printer head cables. In this case, the resistive element can be made to extend over the orifice (72) in a valve body (73) and by exciting the element with electrical current using suitable control means (74) a strain gauge can be formed. This will allow the pressure in a reservoir (not shown) to be monitored. By supplying a sufficiently high current, the membrane (71) can be made to rupture as described above. This form of vaive will be particularly useful where it is important to measure reservoir pressure as a separate pressure monitoring system is obviated. Also, the control means (74) can be configured to cause rupture of the membrane where the pressure level in the reservoir exceeds a certain limit. One application of a valve according to the invention is shown in Figure 6. Here, a trunk (80) is shown for use in transporting cash and, in conventional fashion is supplied with a lid (81) hingedly secured thereto and a handle (82). The lid (81) is selectively lockable to prevent access to the trunk (80), and the locking mechanism is controlled through a key pad (83) and a processor (not shown). A pressurised cylinder (84) containing a banknote staining die is secured inside the trunk (80) by straps (85). The container (80) has a nozzle (86) with a valve described with reference to Figures 1 and 2 preventing flow through the nozzle (86). A battery (87) provides the processor with electrical power and is also used to open the valve. In use, the trunk (80) is loaded with cash and locked and can only be opened when a code is entered using the key pad (83). If the lid (81) is forced open, or the incorrect code entered, the processor acts as a switch to create a closed circuit between the battery (87) and the valve in the nozzle (86) to open the valve. In this way, the contents of the container (84) can be reliable and quickly dispensed into the trunk. Clearly, the processor could be programmable to only allow opening of the lid after a predetermined time or could even include a receiving unit for a remote signal to allow remote operation of the valve.

Claims: CLAIMS 1. A valve comprising a body with a flow path therethrough, a membrane associated with the flow path to prevent fluid flow therethrough, and radiation means located adjacent at least part of the membrane and selectively operable to irradiate the membrane to cause weakening or destruction of at least a part thereof. 2. A valve as claimed in claim 1 wherein the radiation means operatively emits heat. 3. A valve as claimed in claim 2 wherein radiation means is an electrically resistive element. 4. A valve as claimed in any one of the preceding claims wherein the body is in the form of a board with at least one orifice therethrough defining the flow path. 5. A valve as claimed in claim 3 and claim 4 wherein the board is a circuit board with a resistive element printed thereon. 6. A valve as claimed in claim 4 or claim 5 wherein the resistive element extends at least partially around the circumference of the at least one orifice. 7. A valve as claimed in any one of the preceding claims in which the membrane is made of a plastics material. 8. A valve as claimed in any one of the preceding claims in which the membrane is adhesively secured to the body over one end of the flow path. 9. A valve as claimed in any one of the preceding claims in which the membrane is formed from a number of layers. 10. A valve as claimed in any one of the preceding claims in which the radiation means abuts at least part of the membrane. - o - 11. A valve as claimed in any one of the preceding claims in which the body is securable to a reservoir with the flow path adjacent an outlet from the reservoir. 12. A valve as claimed in any one of the preceding claims in which the radiation means is connected through a switch to electricity supply means. 13. A valve as claimed in claim 12 in which the electricity means is battery or mains supply. 14. A valve as claimed in claim 3 in which the resistive element is printed on the membrane. 15. A valve as claimed in any one of claims 1 to 4 in which the radiation means is captured within the membrane.

Inventors: LUBBE LESLIE GERHARD, LUBBE, LESLIE, GERHARD
Applicants: CHENGETA CUTHBERT, LUBBE LESLIE GERHARD, CHENGETA, CUTHBERT, LUBBE, LESLIE, GERHARD
Application year: 1998
Main classification: F16K31
IPC codes: F16K17, F16K31