ES246956A1 - Percussion fuze for projectiles without rifling - Google Patents

Abstract

An impact operated fuze for unrotated projectiles, which may be set for delayed or undelayed action, comprises a body 10 housing a spring-driven barrel 18 with three longitudinal bores 18a, 18b, 18c, each of which can be brought into alignment with a firing-pin 12 slidable in a fuze cap 11. Bore 18a is empty, while bore 18b houses an instantaneous detonator and bore 18c houses a delayed-action detonator. The barrel arbor 19, which is surrounded by the driving-spring 23, carries an escapement wheel 27 locked by an inertia mass 35 and the barrel has a peripheral gear-ring 18f meshing with a pinion 24 carried by a pin 25, which also carries a regulator 26. To set the fuze, a transverse key 29 is rotated to one of three positions indicated by a projecting pin 30. A ball 31 pressed by a spring 32 engages notches 29b in the key to hold the key in the set position. A projecting finger 29c of the key 29, when set in the intermediate (inoperative) position, engages a cam surface 18g of the barrel to prevent rotation thereof, as in Fig. 4, the empty bore 18a then being aligned with the pin 12. When the pointer 30 is set to the appropriate detonator reading, the finger 29c is moved into the path of a pin 34 on the barrel, so that when the barrel rotates it is brought to rest with the bore 18b or 18c aligned with the pin 12. A spring 36 holding the mass 35 in the locking position absorbs shock due to jolts during transport and a further spring 37 prevents the bolt 35 dropping out if the cap 11 is removed. With the key 29 turned to the neutral position, the bolt 35 is also locked by the finger 29c engaging a shoulder 35e. After setting the fuze to operate, say, without delay, and firing the projectile, the striker 13 moves back due to inertia and stresses the spring 14 which later returns the striker to the forward position. At the same time the mass 35 sets back, forcing the spring 37 out of its groove, the spring 37 then moving against shoulder 35a to hold the bolt 35 retracted. The escapement 27 is then free and the barrel 18 rotates, its speed being determined by the regulator 26, until the pin 34 hits the finger 29c. The bore 18b is then aligned with the pin 12 and the fuze armed for operation on impact. By omitting gear-teeth over a portion of the ring 18f and so disengaging the pinion 24, the motion of the barrel between settings 18b and 18c is rendered almost instantaneous. To provide additional safety during transport, a second inertia mass is provided in a bore parallel to the mass 35 and a spring holds the second mass in a forward position to prevent escape of a ball locking the mass 35 in its forward position. The second mass thus delays rearward movement of the mass 35 and subsequent arming of the fuze. In a modification, the positions of the two inertia masses are interchanged, Fig. 6, and from the outer bolt 135 a finger 136 projects into engagement with the teeth 18f of the barrel. Instead of inserting the ball 52 through an opening in the body 10 normally closed by a screw plug, the ball may be placed between the bolts 135, 150 and secured by a plate 108 before securing the nose cap 11. Instead of ball 31, a bolt may be used to hold the key 29 in the selected position, a resilient arm of the plate 108 being used to hold the bolt in place of the spring 32. The finger 29c may be omitted, and a milled surface on the key 29 be used to arrest the stop-pin 34. A plate 118 holds the fuze parts in position should the nose cap 11 be removed at any time for inspection purposes. A safety-pin 132, removed by hand before loading the gun, extends partly round the fuze, Fig. 6, and through a transverse bore into engagement with a groove 150a in the inertia bolt 150. The fuze may be arranged for operation on oblique impact, a weight then moving forward to swing toggle levers and so drive the firing-pin against the primer.