Patent GB-688882-A (GB)
Title: Improvements in or relating to fuzes for projectiles
IPC: F42C9/16
Filed: 1951-05-09
Abstract: 688,882. Projectile fuzes. MEFINA SOC. ANON. May 9, 1951 [May 20, 1950], No. 10875/51. Class 9(i) A projectile fuze, in which the firing pin is locked by at least two locking members, has two coaxial elements rotatable one within the other under the action of the locking members, the outer element having at least one opening adjacent to a ramp co-operating successively with the locking members which are guided in a bore of the inner element. Furthermore means are provided to prevent relative rotation of the two elements for a predetermined time after firing of the projectile. The fuze has a body 1 in which is mounted a firing pin 2 with a flange 3 on which bears a slidable member 4 forming part of a self-destruction device. The member 4 is influenced by a spring 5 bearing against a shoulder 6 of the fuze body. Bores 7 in the slidable member accommodate plungers 8 bearing against a conical surface of a guide 10 below which are coaxial elements 11, 12, the inner element 11 having an axial bore 13 in which the firing pin can slide to strike a primer 14. The firing pin is locked by four slidable members 16 projecting from bores in the element 11, Figs. 2 and 5. The outer element 12 has three bores 17a, 17b, 17c, each ending in a ramp 18a, &c., along which the locking members 16 slide to escape into the boxes 17 as the element 11 rotates in the member 12 under centrifugal force. The elements 11, 12 are locked together during storage by a device 19 having a portion of reduced diameter seated in a bore of the element 11. The wider end of the device 19 is held in the element 12 by a spring. 22 surrounding the element. On firing the projectile the spring 22 moves outwards under centrifugal force to lie against the wall of the annular seating 23 and so frees the locking member 19, which leaves its seating when the angular acceleration ceases and so frees the member 11. Meanwhile, under centri- . fugal force, the plungers 8 bearing on the surface 9 produce an axial movement of the part 4 to stress the spring 5 and free the firing pin 2. As the projectile leaves the muzzle, angular acceleration ceases, the element 11 is unlocked and the locking members 16 slide along their respective ramps, which slope away from the axis of the fuze in the direction of rotation of the projectile. As the member 16a enters the bore 17a, the rotation of the element 11 is stopped until the member escapes from the element 11. The locking members 16b, 16c similarly bring the element 11 to a standstill, while the member 16d enters the opening 17a behind the member 16a, Fig. 5, locking the elements 11, 12 together and cleaning the path of the firing pin. The firing pin is then armed so that on impact or by operation of the self-destruction device the pin strikes the primer 14. In a modification the element 11 is fixed relative to the projectile, while the element 12 is free to rotate around the element 11. In this .second instruction the ramps are of opposite hand to the direction of rotation of the projectile. The number of locking members may be varied and instead of cylinders, prisms, balls &c. other shapes slidable in a seating may be used. When the speed of rotation of the fuze is low or the mass of the rotatable element is small compared with that of the locking member 19 the axis of the member 19 is arranged so that it does not intersect the axis of the fuze, as at 19a, Fig. 2. A stop may be provided to prevent any undesired rotation of the elements 11, 12 relative to each other. Specification 653,547 is referred to.