Patent GB-522990-A (GB)
Title: Improvements in or relating to time fuzes for projectiles and in particular aerial bombs
IPC: F42C11/00
Filed: 1938-12-22
Abstract: 522,990. Projectile fuzes. MEISEL, P. Dec. 22, 1938, No. 37366. [Class 9 (i)]  A time fuze for projectiles, bombs or the like comprises a pressure reservoir containing compressed gas and having a controllable outlet through which the pressure in the reservoir is reduced independently of the position and movement of the projectile, the arrangement being such that the igniter of the projectile or bomb is set in. operation after predetermined reduction of pressure has been attained. Fig. 1 shows a fuze having an electric igniter whilst Fig. 2 shows a modification employing a mechanical igniter. The fuze comprises a cylindrical sleeve 10 closed at one end by a cover 11 and containing a fixed and rigid partition 16 on one side of which is mounted a flexible body 14 having a flexible end 12 and on the other side a flexible body 15 which forms the pressure reservoir and is filled with a gas, such as carbonic acid, under pressure. The lower end of the body 15 is loaded by a spring 30 and, as shown in Fig. 1, is connected with a rod 31 having at its end a roller 32. A needle 18 carried by the end 12 extends, into a nozzle 17 carried by the partition 16 and serving to connect the interiors of the bodies 14, 15. The end 12 is loaded on one side by a pressure spring 19 and on the other side by a pressure screw 23 inserted in the cover 11 and regulated by a knob 24, the time scale of which can be read off by means of a pointer 25. The interior of the body 14 is connected by a tube 20 with a bore 48 in which is mounted a spring-pressed striker 49 having the cross-sectional form of a star, Fig. 3 (not shown). The striker is normally held back by an abutment 80'attached to a cord 82 with a ring 81 at its outer end. The igniter consists of a dry battery 40 to which is connected a heating device consisting of a nickel-chromium resistance wire 46 wound on a clay cylinder 45 filled with an easily ignitable mass, such as a mixture of potassium chlorate and tar. A fuze cord 47 inserted in the cylinder extends with its free ends into the charge 2. Between the projectile body 1 and the charge- 2 is arranged a shield of woven wire 52, which, for the purpose of insulation is dipped in asphalt and coated on both sides with waxed paper. A projection 52<SP>1</SP> of this shield extends between the bore 48 and the outer casing of the projectile. Similar wire shields 53, 54, are fitted in the hollow of the nose 3 of the projectile and in the space between the tube 5 and sleeve 10, the shields 52, 54 being conductively connected together by an elastic button contact 55. The battery 40 together with the delay-action and heating device are embedded in wax 7 in the-tube 5. In operation, before discharge of the projectile or bomb, the cord 82 with the abutment 80 is withdrawn so that the striker 49 is forced by its spring through a lead plug 21, Fig. 2, in the tube 20 and thus frees an outlet to the atmosphere for the  compressed gas in the body 15, the outflow of the gas being regulated to give the desired delay action by adjustment of the needle 18 by the screw 23. The. body 15 thereupon contracts until, at the end of the predetermined time interval, the conductive roller 32 on the metallic rod 31 touches the contact 33. A circuit is then completed from contact 33 through rod 31, body 15, sleeve 10, tube 20, striker 49, tube 5, battery 40 and resistance 46 back to the contact 33 and the cylinder 45 commences to heat up until the fuel therein ignites, thus igniting the fuze cord 47 and the charge 2. The wire shields 52, 53, 54 make it impossible to render the bomb innocuous, e.g., by boring through the body 1 or nose 3. In the case of the mechanical igniter, Fig. 2, the sleeve 10 is provided at its lower end with a cylindrical attachment 59 in which is arranged a cap 65 containing a priming charge 72. A striker 32<SP>1</SP>, loaded by a spring 61, terminates at its upper end in a quadrangular profile one side 59' of which seats within a guide member 57 on the base of the sleeve 10 against a similar surface of the quadrangular profile of a rod 31' hingedly connected with the bottom of the body 15. As the body 15 contracts due to the outflow of gas therefrom, the rod 31<SP>1</SP> and striker 32<SP>1</SP> are drawn upwardly against the action of the spring 61 until the quadrangular parts come out of the guide 57 whereupon the rod 31<SP>1</SP> swings outwards and frees the striker 32<SP>1</SP> which, under the action of its spring, is driven against the charge 72 thereby igniting the charge 2 and exploding the bomb.