AU2003294878B2

AU2003294878B2 - Gas generator for buoyancy bags of watercraft

Info

Publication number: AU2003294878B2
Application number: AU2003294878A
Authority: AU
Inventors: Alfred Eckel; Ulrich Schleicher
Original assignee: Diehl Munitionssysteme GmbH and Co KG
Current assignee: Diehl BGT Defence GmbH and Co KG
Priority date: 2002-12-21
Filing date: 2003-12-17
Publication date: 2010-02-11
Anticipated expiration: 2023-12-17
Also published as: DE50305658D1; TWI265129B; ATE344757T1; WO2004056649A1; TW200420471A; BR0316213B1; BR0316213A; EP1599380B1; EP1599380A1; AU2003294878A1

Abstract

Disclosed is a gas generator (10) for buoyancy bags (42) of watercraft, which operates according to the high-low pressure system and comprises a gas-cooling arrangement that consists of spaced-apart wire baskets (30). Said wire baskets (30) are filled with granulate (32) that endothermically reacts with the propellant gas.

Description

- 1 GAS GENERATOR FOR BUOYANCY BAGS OF WATER CRAFT The invention relates to a gas generator for buoyancy bags of water craft. Submarines require a flotation bladder or tank for normal operation but also 5 to cover the situation of an accident. The previous system disclosed in EP 0 736 450 BI has the disadvantage that admittedly a very large amount of gas - "gas Vdive cell - is produced, but that gas can escape through leakage in the dive cell. The submarine is admittedly raised but begins to sink again very quickly and then goes irrevocably to the bottom of the sea. That process is intensified by virtue of the fact 10 that the gas flows in a very hot condition into the dive cell and therein - as a consequence of rapid cooling of the gas - again experiences a reduction in its volume. Further disadvantages are that the gas involved is explosive and its initial substances are a strong fish poison. The object of the invention is to propose a rescue system which does not 15 suffer from the above-indicated disadvantages. The invention provides a gas generator for buoyancy bags of water craft in accordance with the high-low-pressure system having a tubular casing, arranged therein a high-pressure chamber with igniter device and a gas-supplying composition, a low-pressure chamber with an expansion chamber, and therebetween 20 a wall with a throttle and a sieve which closes off the discharge flow opening of the tubular casing, wherein in the low-pressure chamber the gas which flows out of the throttle can be laterally deflected by an impingement plate, for subsequent gas cooling there are provided at least two wire baskets with granular material, which are disposed in succession at a spacing, and the wire baskets completely fill the free 25 cross-section of the tubular casing. The proposed system comprises a plurality of modules which in turn substantially comprise an inflatable bag and a gas generator. As the gas generator only has to produce so much gas - as the gas is held by the bag - that the bag is fully inflated at the greatest depth, the gas generator can be markedly smaller than that 30 known from EP 0 736 450 BI. It will be noted however that this system requires a relatively long blowing time on the part 12 1 01/10,va 14915 pi speci.doc.I 2 of the gas generator and relatively cold gas (damage to the bag, reduction in the surface area by cooling). Further advantages are: - the gas production rate is independent of the ambient pressure, 5 down to the design depth, - the gas is cold, and for that reason also no loss of buoyancy is incurred due to cooling. When used in relation to a submarine, the arrangement guarantees that the submarine can be kept at the surface of the water for at least half an hour. There is thus sufficient time to allow the 10 crew to climb out. - Neither the initial substances of the gas composition nor the reaction products thereof are explosive or toxic. - The gas volume required is smaller than/equal to that of the dive cells, that is to say only relatively small gas generators are required - and it 15 is thereby in a position to operate redundantly. - The smaller volume and the lower weight of the system make it possible for the buoyancy units, in accordance with German patent DE 197 52 498 C2 to the applicants - while fixed to catch lines - to be caused to float up in the dive cells and to make optimum use of the available space. 20 An embodiment of the invention is illustrated in the drawing. A gas generator 10 comprises a two-stage tubular casing 12 with a high and a low pressure chamber 14, 16 respectively. The two chambers 14, 16 are connected together through a throttle 18. Disposed in the high pressure chamber 14 are the gas-supplying composition 20 and the igniter 25 device 22. The gas produced in the high-pressure chamber 14, see the arrows 24, flows through the throttle 18 into the low-pressure chamber 16. Disposed therein at a spacing 26 is an impingement plate 28 of graphite for deflecting the gas. Five wire baskets 30 with sieves 33 and with granular material 32 of an ablative cooling system are disposed in succession in the 30 low-pressure chamber 16. The wire baskets 30 bear in gap-free relationship against the inside wall of the tubular casing 12. The granular material has the property that, by endothermic reaction, it cools the gas which flows out of the throttle 18 and is deflected by the impingement plate 28, as 3 indicated by the arrows 24. Furthermore the granular material 32 additionally produces gas. Advantageously the impingement plate 28 as well as subsequently disposed sieves 33 and granular material-free intermediate spaces 34 5 provide that passages are not formed in the wire baskets 30, due to destruction of the granular material 32. The granular material 32 is completely converted into gas by burning away over its entire surface area and in uniformly progressive fashion, corresponding to the cross-section of the wire baskets 30. The throttle 18 not only determines the volume flow of 10 the gas but also ensures that, up to an - adjustable - level of the external pressure corresponding to the depth of water, burning-away of the composition 20 takes place independently of the external pressure, that is to say from the surface of the water down to the design depth, the amount of gas and the gas rate produced by the gas generator 10 are constant. 15 Relief or expansion chambers 34 are provided between the wire baskets 30. The chambers 34 serve as gas collection and gas guide devices. They serve to guide the gas through the granular material 32 with the minimum possible level of losses, in such a way that the gas is cooled down to the desired temperature, by the reactions which occur in that 20 situation. The composition 20 is disposed together with the diagrammatically illustrated igniter device 36 in the cylindrical high-pressure chamber 14. The throttle 18 is fitted into a wall 38 which separates the high and low pressure chambers 14, 16 from each other. The hot gas flows through the 25 throttle 18 at the speed of sound, M = 1, in the narrowest cross-section, into a distributor chamber 40 of the low-pressure chamber 16. The gas issues from the throttle 18 at about 1000 0 C. After impinging against the impingement plate 28 the gas flows over a large surface area into the first wire basket 30 with the cooling and also gas-generating 30 granular material 32. After a first endothermic reaction in the first wire basket 30 the gas expands in accordance with the cross-section through the first sieve 33 in the first expansion chamber 34 in accordance with a spacing 35 and then passes into the second wire basket 30.1.

-4 The above-described processes are repeated until arriving at the last expansion chamber 34.5 which corresponds to the volume of a gas bag 42. The gas bag 42 with a gas volume of 1m 3 is fixed to the end 44 of the gas generator 10 by way of a flange fixing 46. 5 A distributor sieve 28 is fixed in opposite relationship, by way of a flange 50. The gas-supplying composition 20 is of a diameter of 240 mm with a height of 82 mm. The length 11 of the gas generator is 500 mm. Tests showed that the gas which flows out of the throttle 18 at a temperature of about 1100 degrees Celsius is at a temperature of about 75*C at the distributor sieve 48, in 10 a depth of water of 24 metres. In that case the volume of gas produced was 3.4 m 3. The so called blowing time was 135.5. The temperature was therefore substantially below the limit temperature of 1 00 0 C which is predetermined for the fabric of the gas bag. Temperature setting of the gas at the distributor sieve 48 is effected in a simple 15 fashion over the total of the lengths 52 of the granular material 32 in the respective wire baskets 30 - 30.4. The tubular casing 12 is of a circular cross-section. That cross-sectional shape is not obligatory. It is possible to select any desired cross-sectional shape. Where the terms "comprise", "comprises", "comprised" or "comprising" are used 20 in this specification, they are to be interpreted as specifying the presence of the stated features, integers, steps or components referred to, but not to preclude the presence or addition of one or more other feature, integer, step, component or group thereof.

Claims

1. A gas generator for buoyancy bags of water craft in accordance with the high low-pressure system having a tubular casing, arranged therein a high-pressure 5 chamber with igniter device and a gas-supplying composition, a low-pressure chamber with an expansion chamber, and therebetween a wall with a throttle and a sieve which closes off the discharge flow opening of the tubular casing, wherein 10 in the low-pressure chamber the gas which flows out of the throttle can be laterally deflected by an impingement plate, for subsequent gas cooling there are provided at least two wire baskets with granular material, which are disposed in succession at a spacing, and the wire baskets completely fill the free cross-section of the tubular casing. 15

2. A gas generator according to claim 1 further including an ablative cooling system.

3. A gas generator according to claim 1 wherein said the impingement plate is 20 provided at the first wire basket.

4. A gas generator according to claim 1 wherein the volume defined by the spacing between two wire baskets serves as a gas collection and gas guide device. 25

5. A gas generator substantially as hereinbefore described with reference to the accompanying drawing. 12/01/10,va 14915 claims.doc,5