GB2119485A

GB2119485A - Fuze safety mechanism

Info

Publication number: GB2119485A
Application number: GB08311844A
Authority: GB
Inventors: Olof Nygards
Original assignee: Bofors AB
Current assignee: Saab Bofors AB
Priority date: 1982-04-30
Filing date: 1983-04-29
Publication date: 1983-11-16
Also published as: NO158438C; SE8202721L; GB8311844D0; CH661793A5; NO831529L; NO158438B; FR2526156B1; FR2526156A1; DE3315560C2; SE430722B; GB2119485B; DE3315560A1

Abstract

The present invention relates to a safety device comprising a housing (1) and a movable rotor member (2) which in a safe position is locked in said housing but when released is arranged to be moved during which movement a primer charge (6) is brought by the rotor member (2) from a safe position at the side of an "eye" (7) to an armed position in line with the "eye". An initiating electric igniter (11) for the primer charge (6) is cooperating with or comprises a penetrating small body (12) which could be shot or pushed away. The primer charge (6) is arranged in the rotor member (2) behind a barrier (16) preventing the initiation of the charge for (6). When the penetrating small body (12) is shot in the armed position it penetrates the barrier (16) and the primer charge (6) is initiated. The rotor member (2) comprises a protecting tongue (18) which in the safe position is aligned with the "eye" (7) so that if the initiating igniter (11) is activated in the safe position (accidental ignition) then the penetrating small body (2) is prevented from reaching the "eye" (7) at the same time as the protecting tongue (18) is deformed or bent by the body (12). By this deformation or dislocation the protecting tongue (18) comes into engagement with a stop member (20) which prevents the rotor member movement to commence or continue. In this way, the rotor member (2) is prevented from bringing the primer charge (6) into the armed position in line with the "eye" (7). <IMAGE>

Description

SPECIFICATION Safety device useful in conjunction with ammunition units or the like The present invention relates to safety devices for use with ammunition units or the like, and comprising a first part, and a relatively movable second part which in the safe position is locked to the first part but when released therefrom is arranged to move a primer charge from a safe position to an armed position in register with the "eye" of a main charge.

It is previously known to arrange two different safety elements in a fuse safety device for ammunition units comprising a first part, for instance a housing of the safety device, and a second part, for instance a rotor member which is locked in the housing in the safe position but released from the housing when said safety elements are released in a predetermined order.

When the rotor member has been released it is free to move and brings the primer charge from a safe position to an armed position in line with the "eye" of the fuse.

It would be desirable to be able to use electric igniters for the different safety elements. For example, it can be mentioned that there is a desire to use an electronic arming igniter8s well as an electronic initiating igniter in connection with a safety device having the aforementioned housing and rotor element. However, the use of such electric igniters makes the releasing chain as such very sensitive to external disturbances so that there is a danger that the safety system may be released accidentally.

In order to obtain a safer electric arming igniter, an electric igniter can be used which is located in the housing of the safety device and which, when initiated, is arranged to generate a gas which shoots or pushes away a locking pin, which in the safe position locks the rotor member in the housing, into a recess in the rotor member so as to release the rotor member from the housing.

However, there is a risk that some of the gas generated by the electric arming igniter could go through the small gap between the housing and the rotor member and reach the primer charge which then could be initiated if specific measures were not taken.

The present invention has been made from a consideration of the above discussed problems.

Broadly, the present invention provides an ignition system for an ammunition unit or the like, which comprises an initiating igniter, a main charge spaced from said igniter, and a primer charge for initiating said main charge and relatively movable with respect to said igniter and said main charge from a safe position in which it is out of register with said main charge into an armed position in register with said main charge and between said main charge and said igniter, said primer charge being adapted to be initiated in the armed position for initiating said main charge by impact of a moving body released by said igniter upon actuation thereof, wherein, in order to prevent said body from directly initiating said main charge upon premature actuation of said igniter before said primer charge is in its armed position, there is provided a protecting member which, when said primer charge is in the safe position, is disposed in the path of travel of said body towards said main charge to intercept said travel and which is removed out of said path upon movement of said primer charge into its armed position, said protecting member being displaceable or deformable upon impact of said body therewith into engagement with a stop member whereby movement of said primer charge to the armed position is then prevented.

Preferred embodiments of the present invention have an initiating igniter, preferably an electronic igniter, for the primer charge (which may be for instance a detonator cap) which cooperates with or comprises a penetrating part in the form of a small body. The primer charge is arranged in a movable part of the device behind a barrier for preventing initiation and which barrier preferably is made of the material forming the movable part. In the armed position, the penetrating part is pushed away on actuation of the igniter and penetrates the barrier to initiate the primer charge which in turn then initiates the main charge.However, should the penetrating part accidentally be released before the primer charge is in the armed position, then it is prevented from accidentally initiating the main charge by the protecting member which not only stops the movement of the penetrating part towards the main charge but is displaced or deformed on impact with the penetrating member into engagement with a stop with which it then cooperates to prevent movement of the primer charge into the armed position.

In specific embodiments of the invention, the primer charge is arranged in the movable part of the device in a recess extending from a first surface of the movable part towards but not as far as a second surface of this part. The material remaining between the bottom of the recess and the second surface then forms the barrier. The protecting member is made in the form of a protecting tongue which is deformed or bent by the penetrating part should this be released whilst the primer charge is in the safe position. The stop member is preferably made as a boss or the like which is fixed with respect to the movable part, and with which the deformed or bent protecting tongue is arranged to come into engagement.

Such a safety device is particularly adapted to be used in conjunction with a second safety arrangement of the kind referred to above in which the movable part is locked in the safe position until the second safety arrangement is released by initiation of an arming igniter which generates a gas which removes a locking pin from its locking position.

The preferred embodiments of the invention thus provide a barrier through which the penetrating body has to be forced in order to reach and initiate the primer charge, for instance a detonator cap. The primer charge is thus protected when the arming, preferably electric, igniter is initiated and the locking pin is pushed away. The gas which is used for removing the pin is effectively prevented from reaching and initiatinq the detonator cap. Thanks to the use of the penetrating body, a more precise ignition of the primer charge can be achieved. Without such a penetrating body the entire barrier would have to be pressed down, which could result in an uncontrolled ignition.In the event of premature ignition of the arming igniter the pretecting member or tongue serves to prevent the penetrating body from initiating the main charge, but instead the deformation or bending of the protecting member which results from the impact of the penetrating member therewith is used for locking the movable part so that it is prevented from completing its movement to the armed position. In this event, therefore, the primer charge is prevented from reaching its position in which it is in line with, for example, the "eye" of the main charge.

A preferred embodiment of the safety device according to the invention will now be described in more detail with reference to the accompanying drawings, in which: Figure 1 is a vertical section through a part of a fuse safety device for an ammunition unit comprising a housing and a corresponding rotor member and which is provided with an arming electric igniter as well as an initiating electric igniter; Figure 2 is a further vertical section through the housing and the rotor member shown in Figure 1; Figure 3 is a horizontal section through the rotor member on the line 3-3 of Figure 2 and illustrating a protecting tongue; and Figure 4 is a vertical section through the parts shown in Figure 2, but in which the protecting tongue has been deformed by a penetrating small body pushed away upon actuation of the initiating electric igniter.

Figure 1 illustrates the main parts of a conventional fuse safety device for an ammunition unit which comprises a housing 1 and a rotor mernber 2. The rotor member is locked in the housing by means of a safety element 3 in the safe, i.e. not released, position. The safety element 3, for example, may comprise an arming electric igniter which is initiated when the ammunition unit is inserted into or fired from a gun barrel. In the illustrated embodiment the arming electric igniter comprises a locking pin 4 which in the safe position of the igniter locks the rotor member in the housing 1.When the arming electric igniter is initiated, the locking pin 4 is completely pushed into a recess 5 in the rotor member 2 so that the rotor member is released and free to move with respect to the housing 1 to bring a detonator cap 6 from a safe position at the side of an "eye" 7 of a main charge to an armed position in line with the eye.

Figure 1 illustrates the case in which said locking pin 4 has been completely pushed into the rotor recess 5 so that the rotor member has been free to fully rotate to the armed position in which the detonator cap 6 is brought just in front of the eye 7. The shooting of the locking pin 4 into the corresponding recess 5 can, for example, be brought about by means of a powder charge ignited by an electric resistance bridge in the arming igniter.

Such a resistance bridge is initiated by means of electrical circuits in the ammunition unit. In the safe position of the arming igniter (not shown in Figure 1 ) the upper portion of the locking pin 4 was located in a recess 8 of the housing 1 which was in line with the rotor recess 5. In this safe position the lower portion of the locking pin 4 was engaged in the rotor recess 5 so that the rotor member was locked in the housing 1 and prevented from being moved. The housing 1 is also comprising a recess 9 for said arming igniter which recess 9 coincides with the recess 8. The axis of rotation of the rotor element has been indicated by the line 10 on Figure 1.

The safety elements also comprise an initiating electric igniter 11 which can be initiated at the impact of the ammunition unit or the like. The initiating igniter comprises electric circuits 1 a which are sensitive to an impact or the like and initiate a powder charge 2 b or the like in the igniter. The initiating igniter comprises or cooperates with a penetrating small body 12, which is arranged in a recess 13 in the housing which coincides with a wider recess 14 housing the initiating igniter 11 a, 11 b. When the powder charge 1 b is activated the small body 12 is shot or pushed away.

The rotor member 2 has an under surface 2a and an upper surface 2b. The rotor member is furthermore provided with a recess 1 5 in which the detonator cap 6 is arranged. The recess 1 5 extends from the under surface 2a towards the upper surface but ends at a specific distance from said upper surface so that the remaining material 1 6 forms a barrier or "roof" to the recess.As will be seen, even when rotor member 2 has brought the detonator cap 6 to the armed position indicated in Figure 1, i.e. in line with the "eye" 7, there is still no free passage to the detonator cap 6 for the small body 12 because of the presence of the barrier 1 6. Rather, the initiating igniter has to shoot or push away the body 12 in such a way that the barrier 1 6 is penetrated in order to ignite a primer charge 6a of the detonator cap. The ignition of the primer charge 6a and the consequential ignition of the detonator charge 6b and the main charge (not shown) of an ammunition unit through the eye 7 is known per se. Although the detonator cap 6 is shown as being provided with a specific primer charge 6a and a detonator charge 6b this is not essential and for example it can alternatively comprise a single charge. Under the detonator cap there is a further safety plate 1 7 which is fixed with respect to the rotor member 2. When the detonator charge 6b is initiated the plate 1 7 is penetrated by the detonator wave so that the main charge is initiated through the eye 7.

The safety device shown in Figure 1 is intended to function in the following way. The arming electric igniter is activated before the initiating electric igniter. As already mentioned the arming igniter is activated at a specific distance from the muzzle of the gun barrel. The rotor member 2 is then released and rotated by means of driving means which are known per se. After a certain time, determined by the angular velocity, the detonator cap 6 has been brought into alignment with the eye 7. When the initiating igniter is activated, the penetrating body 12 is shot through the barrier 1 6 and initiates the detonator cap 6, which then also initiates the main charge of the ammunition unit.

However, if the initiating igniter for some reason should be initiated before the arming igniter, it is desired that the ignition of the detonator cap and the main charge should be prevented. To this end, the rotor member is provided with a protecting member in the form of a tongue 18 as illustrated in Figure 2, in which the rotor member is shown in its safe or initial position. In this initial position the detonator cap (not illustrated in Figure 2) is in a position at the side of the eye 7, in the member 19. This member 1 9 is a separate body with respect to the safety plate 17. As shown in Figure 2, the arming igniter has not been initiated which means that the rotor member is locked in the housing 1.If now the initiating igniter is activated unintentionally, the protecting tongue 1 8 serves to prevent the body 12 from reaching the plate 17, the eye 7 and hence the main charge.

The plate 17 is also provided with a stop member 20. The protecting tongue 18 is arranged so that it is bent by the body 12 if this body is pushed away unintentionally on actuation of the initiating igniter whilst in the safe position. When the protecting tongue 18 is not deformed by unintentional release of the penetrating body 1 2, i.e. the intended situation then it remains disengaged from the stop member 20. If the tongue has been deformed or bent, however, (see Figure 4), then the tongue comes into engagement with the stop member 20 so that the rotor member is prevented from commencing or continuing its rotational movement, indicated by the arrow P1 in Figure 3.

The safety arrangement which has been described above thus functions so that if the two safety elements (igniters 3 and 11) are initiated in a correct order then the protecting tongue can pass the stop member 20. If however the initiating igniter is activated before the arming igniter then the protecting tongue is deformed or bent so that it comes into engagement with the stop member 20 and prevents the rotor member from rotation and thereby prevents the detonator cap 6 from coming into position in line with the eye 7. The protecting tongue 1 8 therefore has two functions, i.e. to stop the rotor member 2 and to prevent the body 12 from reaching the eye 7.

The stop member 20 has been illustrated as a boss, but of course also other arrangements are possible. Also the protecting member can take other forms.

The invention can be used for other types of safety elements utilizing electric igniters. In the illustrated embodiment the gas which is used for driving the locking pin 4 in the arming igniter is prevented from reaching the detonator cap 6 via the small passage 21 between the rotor member 2 and the housing 1 because of the barrier 16.

Furthermore the gas is prevented from reaching the igniter 11 and initiating the charge 11 b due to the penetrating body 1 2.

Claims

1. An ignition system for an ammunition unit or the like, which comprises an initiating igniter, a main charge spaced from said igniter, and a primer charge for initiating said main charge and relatively movable with respect to said igniter and said main charge from a safe position in which it is out of register with said main charge into an armed position in register with said main charge and between said main charge and said igniter, said primer charge being adapted to be initiated in the armed position for initiating said main charge by impact of a moving body released by said igniter upon actuation thereof, wherein, in order to prevent said body from directly initiating said main charge upon premature actuation of said igniter before said primer charge is in its armed position, there is provided a protecting member which, when said primer charge is in the safe position, is disposed in the path of travel of said body towards said main charge to intercept said travel and which is removed out of said path upon movement of said primer charge into its armed position, said protecting member being displaceable or deformable upon impact of said body therewith into engagement with a stop member whereby movement of said primer charge to the armed position is then prevented.

2. A safety device comprising a first part (1) and a movable second' part (2), which in a safe position is locked to the first part but when released from said first part is arranged to be moved and during which movement a primer charge (6) is brought by this movable second part from a safe position at the side of an "eye" 7 to an armed position in line with the "eye" characterized in that an initiating igniter (1 1), preferably an electronic igniter, for said primer charge (6) is cooperating with or comprises a penetrating part in the form of a small body (12) which can be pushed away; that the primer charge (6) is arranged in said movable second part (2) behind a barrier (1 6) for preventing initiation and which barrier preferably is made of the material forming said second part; that in the armed position said penetrating part (12) when pushed away is penetrating said barrier (16) and initiates the primer charge (6); that said movable second part (2) is provided with a protecting member (18) which in the safe position is in line with the "eye" (7) and prevents the penetrating part (12) to reach the "eye" in case of release of the initiating igniter at the same time as it is deformed or displaced by the penetrating part; and that the protecting member (18) by its deformation or dislocation comes into engagement with a stop member (20) which prevents the movement (P1) of the second part to commence or continue so that the second part is prevented from bringing the primer charge (6) into its armed position in line with the "eye" 7.

3. A safety device according to Claim 2, characterized in that the first and second parts (1, 2) are locked to each other also by means of a second safety element (3) which is arranged to generate a gas when initiated which gas is prevented by said barrier (16) from reaching and initiating said primer charge (6).

4. A safety device according to Claims 2 or 3, characterized in that the primer charge (6) is located in a recess (15) in the movable second part, which recess is extending from a first surface (2a) towards a second surface (2b) but ending a specific distance therefrom; the remaining material (16) between said recess (1 5) and the second surface (2b) forming said barrier (1 6).

5. A safety device according to any one of Claims 2 4, characterized in that the protecting member (18) is formed as a protecting tongue which is deformed or bent by the penetrating part (12) when it is shot in the safe position.

6. A safety device according to any one of Claims 2-5, characterized in that the stop member (20) comprises a boss, shoulder or the like which is fixed with respect to the second part.

7. A safety device according to Claims 5 or 6, characterized in that said protecting tongue (18) when deformed or bent comes into engagement with said boss, shoulder or the like.

8. An ammunition unit having a safety device substantially as hereinbefore described with reference to the accompanying drawings.