Patent GB-489279-A (GB)
Title: Gas pressure generating charges or cartridges for the actuation of mechanical devices
IPC: F42B3/04
Filed: 1937-01-20
Abstract: 489,279. Self-combustible charges for generating gases under pressure. HOLM, J. M., McEWEN, W., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. Jan. 20, 1937, No. 1749. [Classes 9 (i) and 9 (ii)] Relates to slow-burning gas-generating cartridges containing substantially ashless charges and suitable for use in conjunction with mechanical devices of the kind requiring for their operation the development of high pressures, such as, high pressure liquid-ejectors, engine starters, lorry-tipping devices, jacks, presses, electrical switch-gear operating devices, compressed-gas motors and brakes. According to the invention, the cartridge or charge comprises a self-combustible substantially ashless propellent explosive composition in the form of a solid rod which is exposed to ignition at one end only and is protected on its longitudinal surface by a tape or sheet of material tightly wrapped around the rod in the form of an overlapping spiral starting from the ignition end of the rod and forming, in combination with an adhesion-promoting substance, a closely adherent shield which prevents the contact of flame gases with the protected surface of the rod during the combustion thereof. The wrapping material may consist of a fibrous or textile backing material, e.g. woven tape or paper coated and /or impregnated with a cementitious adhesion-promoting material such as a cellulose derivative thermoplastic composition, a resinous composition, a rubber or rubber and oxidized oil composition or a bituminous composition or, alternatively, it may consist of a homogeneous material, such as cellulose acetate, regenerated cellulose or' sheet rubber, in which case the adhesion-promoting material may be a volatile solvent for the wrapping material and /or the propellent itself. Fig. 1 shows a charged cartridge comprising an unlined paper cartridge case 1 having two venting holes a short distance from the metal base 2. The ignition means are situated at the base of the cartridge and comprise the percussion cap 3, a priming charge 4 of Schultze gunpowder and quick match 5 and a disc 6 of non-solvent Ardeer cordite having the composition : nitroglycerine 29 per cent, nitrocellulose 65 per cent, and diethyl diphenyl urea 6 per cent. The main charge 7 consists of a non-solvent Ardeer cordite rod of the same composition tightly wrapped from the ignition end with a length 8 of adhesive electrical insulating tape. A disc 9 of the substance known under the Registered Trade Mark " Plasticine " is pressed on to one end of the rod and held in position by the projecting end of the tape. The wrapped rod is inserted in the case 1 with the exposed end in contact with the disc 6 and the cartridge is closed with a cardboard disc 10 and turnover 11. Fig. 2 shows a modification in which a centrallyperforated white rubber disc 12 is placed between the igniting means and the main charge 7. This charge and the pellet 6 consist of non- solvent Ardeer cordite having the composition nitroglycerine 38À5 per cent, nitrocellulose 47À5 per cent and moderants 14 per cent. The remote end of the charge from the igniting means is protected by a prolongation of the spiral wrapping folded over and pressed against the end surface. Modifications of this construction are described in which the percentage composition of the Ardeer cordite is varied and in one of which two spiral layers of surgical adhesive tape are employed as the wrapping. Fig. 3 shows a further modification in which the cartridge is arranged for forward ignition by means of an electrical fuzehead. The charge in this case consists of a solid homogeneous cylinder 7 of solventless cordite consisting of nitroglycerine 33À5 per cent, nitrocellulose 51 per cent, diethyl diphenylurea 5 per cent, diamyl phthalate 7 per cent and potassium nitrate 1À5 per cent. A length of tape 8 impregnated with an adhesive castor-oil rubber composition is wound round the cylinder in an overlapping spiral so that 10 mm. at one end of the rod is left uncovered. The wrapped cylinder is inserted, sealed end foremost into the case 1, the base 2 of which is fitted with a central electrode 14 within an insulating sleeve 15. One of the leads 13 from the low tension electric fuzehead 17 is connected to the electrode 14 whilst the other is connected to the base 2 at 16. A quick-match fuze 5 and Schultze gunpowder 4 are also loaded in contact with the exposed end of the rod. A still further modification is described consisting of an unenclosed wrapped charge comprising a rod of solventless cordite consisting of nitroglycerine 41 per cent, nitrocellulose 52 per cent and diethyl diphenylurea 7 per cent wrapped in a double overlapping spiral of adhesive tape. 25 mm. of the rod are left exposed at one end and a length of quick-match tape and a lowtension electric fuzehead are bound to this end with cotton thread. If desired, the gas generating charge may be employed as the first charge section or the last portion thereof of the composite gas-generating cartridges claimed in Specification 483,994. Specifications 26430/07, [Class 8], 454,091, and 477,956 also are referred to.