Patent GB-506675-A (GB)
Title: Improvements relating to explosive cartridges for the starting of internal combustion engines or other analogous purposes
IPC: F02N13/00
Filed: 1937-12-08
Abstract: 506,675. Gas -producing cartridges. HERZMARK, N. Dec. 8, 1937. No. 33903. [Classes 9 (i) and 9 (ii)] , , Relates to explosive cartridges for the start. ing of internal-combustion engines, for generating gases to be used for operating piston mechanism of other blinds, such as reciprocating pumps, and piston devices actuating oil-break electrical switches, or the gas may be stored under pressure until required. A suitable gasoperated starter for an internal-combustion engine is described in Specification 366,181, [Group XXVII]. According to the invention, a primerless and caseless gas-generating cartridge comprises a substantially homogeneous body composed mainly of -explosive material, in combination with a plug which is adapted to engage a hole in the cartridge, and means for heating the plug independently of the cartridge, by an electric current or otherwise, in order to fire the cartridge. As shown-in Figs. I and 2, the cartridge 22 is of cylindrical shape with a central bore 32 to accommodate the extremity of a heating plug and a plurality of parallel holes 60 equally spaced apart and around the central bore. The cartridge may be composed of 70 parts nitrocellulose, 28 parts nitroglycerine and small quantities of aromatic nitrates and plastifying materials. Suitable plastifying agents are those mentioned in Specification 457,423, i.e., phthalic esters of primary, secondary or aromatic alcohols, solutions of camphor, glycerine esters, and phenolic or cresylic phosphates, associated or not with volatile solvents. Alternatively, the cartridge may consist of 48 parts corditÚ, 51 parts nitrocellulose (12 per cent nitrogen), 0.7 part diphenylamine and 3 part red or other aniline dye (soluble in alcohol). The rate of combustion of the cartridge can be varied by arranging the holes 60 at suitable distances apart and from the central. bore. As shown in Fig. 2, the heating plug 31 is carried by a breech-bolt 24 rotatable by a handle 25, Fig. 3, so as to feed the cartridge into the combustion chamber, the bolt being provided with helical lugs 26 which engage with corresponding lugs at the sides of the breech chamber for locking the breech in closed position. The plug 31 comprises a metal tube 61 formed towards its front end with a bevelled collar 62. seating in a correspondingly bevelled hole in the front wall 63 of the bolt 24 and having at its rear end screw threads 64 engaging in a correspondingly screwed hole in the rear wall 63a of the bolt. The forward end of the tube terminates in a thin tapered conical wall 65 having a central small hole 66. An electrode 67 surrounded by insulating material 68 passes axially through the tube 61, the head 69 of the electrode fitting tightly within the hole 66, to the edge of which it may be welded. The rear end of the electrode passes out through an insulator 70 and is secured by a nut 71 beyond which is secured an electrical contact disc 72 having its periphery notched at 73. The disc 72 is adapted -to be engaged by a contact plunger 74, Fig. 3, working in an insulating bush in the wall of the breech chamber 23 and operated by a push-button 76, the movement of which is limited by a shoulder, so that plunger 74 can engage the periphery of disc 72 at its extreme outer edge but is unable to make contact with the bottom of the notch 73. The position of this notch in relation to the rotary locking movement of the breech-bolt is such that the notch lies on the side towards the plunger 74 until the bolt 24 has been locked by turning down the handle 25. The plug 31 and switch device 72, 74 are connected up in circuit with a battery 78, the arrangement being such that on operation of the push button 76, the passage of current heats up the head 69 and thin conical wall 65, the heat so produced being transmitted by the plug directly to the central part of the cartridge. The gases pass from the cartridge-firing device 10 through a union 20 into a pipe 21 which conveys them to the inlet port of the starter.