Safety device for a projectile

Dec. 11, 1956

2,773,449

L. A. B. KARSBERG

SAFETY DEVICE FOR A PROJECTILE

Filed Feb. 10, 1953

Sheets-Sheet 1

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Dec. 11, 1956

L. A. B. KARSBERG

2,773,449

SAFETY DEVICE

FOR A PROJECTILE

Filed Feb.

10·, 1953

Sheets-Sheet 2

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United States Patent Office

2,773,449

Patented Dec. 11, 1956

2,773,449

SAFETY DEVICE FOR A PROJECTILE

Lars Anders Birger Karsberg, Karlskoga, Sweden, assignor to Aktiebolaget Bofors, Bofors, Sweden, a corporation of Sweden

Application February 10,1953, Serial No. 336,156

Claims priority, application Sweden February 26,1952

Claims. (Cl. 102—76)

The present invention relates to a safety device for a ⁷⁵projectile.

Such a safety device must on one hand with reasonable certainty prevent an accidental or premature detonation of the projectile. On the other hand, it must with equal certainty assure that the projectile is armed at the ap- ²⁰propriate time.

The principal object of the present invention is to provide a novel and improved safety device which affords a high degree of safety and also assures arming of the projectile at the desired time. ²³

Another object of the present invention is a novel and improved safety device of the general kind above referred to, which includes two arming members both held in a safety position until it is desired to arm the projectile and simultaneously released for movement into the arm- ³⁰ing position. The provision of two arming members doubles the likelihood that the projectile is safely retained in its unarmed position, but actually armed when required.

The present invention will be described more in detail in connection with the drawing where Fig. 1 shows an ³⁵isometric view of a safety device according to the present invention, some of the components being shown as if they were transparent for sake of clarity of the illustration and Fig. 2 shows an isometric section of the safety device.

In the figures, 1 is a cylindrical member. The refer- ⁴θ ence number 2 shows the wall of a projectile, in which the member 1 can be arranged. The cylindrical member 1 includes three parallel holes 3, 4 and 5. The holes 3 and 5 are identical. One end of these two holes is pro- ._ vided with threads 6 and 7, respectively. In each of these ends is screwed a plug 8 and 9, respectively, provided with threads. The said plugs are each provided with an axial hole. The hole of plug 8 is visible in the Fig. 1, and has been given the reference number 10. In each of these holes one end of a spring 11 and 12, respectively, rests. The other ends of the springs 11 and 12, respectively, rest in a reces in one end of cylindrical arming members 14 and 15, respectively. The recess in the member 15 has been given the reference 55 number 13. The members 14 and 15 are provided with peripherical grooves 16 and 17, respectively, which preferably have slanting walls. In these grooves, part of the balls 18 and 19, respectively, rest. The rest of the balls are in a hole 20 extending through the member 1, trans- θθ versely of the holes 3-5. In the said hole, two bars 21 and 22 are arranged. These bars rest with one end each against the balls 18 and 19 and with the other ends against a member 23, and then against two bevelled surfaces of this member. The member 23 is fastened at one 65 end to a spring 24. One end of the said spring is fastened to a screw 25 arranged at the hole 4. At the other end of the member 23, a loop 26 is fastened. Through this loop 26, an incandescent filament 27 runs, the ends of which are fastened to the contacts 28 and 29 mounted on 70 a plate 30, which is arranged in a hole 31 of the member 1. The end contacts 28 and 29 are preferably connected to a voltage source. The non-spring-actuated ends of the two members 14 and 15 are provided with slots 32 and 33, respectively. These slots engage the bar 34 and 35, respectively, arranged in holes 36 and 37, respectively. These holes are perpendicular to holes 3 and 5. Furthermore, the two members 14 and 15 have transverse holes 38 and 39, respectively, which contain a charge each, one of which is visible in the figures, and is marked 40. In the member 1 there are also provided two transverse holes movable into registry with the holes 38 and 39. Only one of these holes is shown in the figures, and has been marked 41. These two last-mentioned holes are intended to function as guides for striking pins. In the figures, one such striking pin 42 is shown in the hole 41. In case the device described above is to function as a safety device for projectiles with hollow charges, the charges in the holes 38 and 39 will be omitted as well as the said striking pins.

The device described above functions as follows. Let it be assumed that the two members 14 and 15 are in the position shown in Fig. 1, i. e. in the hooked-up position. The balls 18 and 19 rest in the grooves 16 and 17. They are kept pressed into the grooves by means of the bars 21 and 22. This retention is caused by the other ends of the bars being separated from each other by the aid of the member 23. In this position, the holes 38 and 39 will be out of line with the hole 41 and the corresponding hole of the member 14. If in this condition a voltage is supplied to the contacts 28 and 29, the incandescent filament 27 will be heated so that it will break. Thereby, the spring 24 will withdraw the member 23 from engagement with the bars 21 and 22. On account of the members 14 and 15 being springactuated and because of the design of the grooves 16 and 17, the balls 18 and 19 will be pressed out of the grooves, and the members 14 and 15 be enabled to move freely. The members will now move into a position such that the ends of their slots will engage the bars 34 and 35. In this position, the members 14 and 15 will be kept at a standstill. The holes 38 and 39 will form a continuation of the hole 41 and the corresponding hole in the member 14. The safety device is now unlocked. One or both of the striking pins can now function, whereby an actuated charge will create a flash. If the safety device has instead been intended for a projectile with a hollow charge, each of the holes 38 and 39 would have formed a passage for flames when the device was unlocked.