GB2119484A

GB2119484A - Fuze safety mechanism

Info

Publication number: GB2119484A
Application number: GB08311843A
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: FR2526155A1; NO158439B; GB2119484B; CH661349A5; NO831528L; FR2526155B1; SE444727B; DE3315561A1; NO158439C; DE3315561C2; GB8311843D0; SE8202720L

Abstract

The invention provides safety means for a safety device (3) in an ammunition unit which safety device (3) is arranged to lock against relative movement a first part (2) with respect to a second part (1) in the safe position. The safety device (3) comprises a sliding member (5) which is arranged to be pushed into a corresponding recess (7) so that when it is completely pushed into the recess it is out of engagement with one of the parts (1, 2) so that the parts are free to move with respect to each other. When the sliding member (5) is pushed into the recess (7) it prevents a further safety device (8) from being released in an improper order with respect to the safety device (3). <IMAGE>

Description

SPECIFICATION Safety arrangement, particularly for electric arming devices of ammunition units The present invention relates to a safety arrangement which for example is useful in conjunction with ammunition units. It has particular, although not exclusive, application to electric arming devices for ammunition units which in the safe position lock a movable part, for instance a timing mechanism member such as a rotor, a sector body or the like, to a fixed part, for instance the housing of the arming device.

It is previously known to provide an ammunition unit with different types of safety devices in order to try to ensure safe handling and release of the ammunition unit. In addition to conventional interruptorswhich are released in the gun barrel on firing, specific arming devices which are released at a predetermined distance from the muzzle of the gun barrel can also be used so that the initiation of the ammunition unit is prevented in the vicinity of the gun barrel. Such arming devices are required in order to protect both the gun crew and one's own troops in the neighbourhood. It is also previously known to release such arming devices electrically, which, however, makes the safety arrangement as a whole sensitive to disturbance sources, specifically electrical disturbance sources.

It would be desirable, therefore, to be able to release the arming devices electrically and still maintain the high degree of reliability required when handling live ammunition units such as shells, projectiles or the like.

Broadly, the present invention provides an ammunition unit incorporating a safety arrangement for preventing unintentional movement of a first part of the ammunition unit relative to a second part thereof and comprising first and second safety devices adapted to be released in that order to permit said relative movement of said parts of said ammunition unit, wherein said second safety device comprises a locking member which in its safe position engages one part of the ammunition unit and which, on release of said second safety device is slidingly moved out of engagement with said one part to be received within a recess in the other part of the ammunition unit, and wherein said safety devices are adapted to cooperate whereby movement of said locking member into said recess locks the first safety device against release if said first safety device has not been released prior to said second safety device.

The safety arrangement of the present invention is particularly adapted for use with an electric arming device which in an ammunition unit is arranged, in the safe position, to lock a movable part, for instance a timing mechanism member such as a rotor, a sector body or the like, to a fixed part, for instance the housing of the arming device.In such embodiments the new safety means preferably comprises a sliding member which, on release of the safety device, is arranged to be pushed out of engagement with the fixed part into a corresponding recess, so that when completely pushed into said recess the movable part is free to be moved with respect to the fixed part, the sliding member when pushed into said recess being arranged to deform the recess wall or deform or lock one or more further safety devices of the ammunition unit in such a way that the latter or these latter safety devices are prevented from being released if they are subjected to their respective releasing factors in the wrong order with respect to the releasing factor for the first-mentioned safety device.

In specific embodiments of this preferred arrangement, the sliding member is formed as a pin, which, when pushed into its recess, deforms the material between the recess and an adjacent recess for a further safety device. These recesses can be disposed with their axes parallel to each other or so as to form an angle therebetween.

Alternatively, when pushed into its recess the sliding pin can come into engagement with a separate body of a further safety device so as to lock or deform the body and prevent it from being moved from or in its own recess. Such body could be used, for instance, in an interruptor, in an acceleration safety device, a rotational safety device or the like.

In spite of a comparatively simple construction, using in preferred embodiments'a sliding pin, a very reliable safety arrangement can be obtained - even if, for example, the arming device is released electrically. The new safety means can easily be incorporated in the ammunition unit together with the other safety devices which are included in the whole safety arrangement.

Preferred embodiments of the safety arrangement 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 safety arrangement of this invention which comprises an electric arming igniter arranged in conjunction with an acceleration safety device, the arming igniter as well as the acceleration safety device being shown in their initial or safe positions; Figure 2 is a vertical section corresponding to Figure 1 but in a position in which the electric arming igniter has been released; Figure 3 is a horizontal section through the safety arrangement illustrated in Figures 1 and 2; Figure 4 is a cross-section through an ammunition unit comprising a safety arrangement of this invention which includes a rotational safety device;; Figure 5 is a vertical section through some parts of safety arrangement comprising an electric arming safety device and an interruptor; Figure 6 is a horizontal section through the safety devices of Figure 5; Figure 7 is a vertical section through the interruptor in its normal functional position; Figure 8 is a vertical section through the interruptor of Figure 7 but during the gun barrel phase; and Figure 9 is a vertical section through the safety device according to Figures 7 and 8 in a locked position in which the movable sector body comprising the interruptor is locked to a fixed part.

The safety arrangement shown in Figure 1 comprises a fixed part 1 and a movable part 2. The fixed part may, for instance, consist of the housing of the safety arrangement, and the movable part may be the rotor or sector body or any other rotatable part of the safety arrangement. An electric arming igniter 3 is arranged in a corresponding recess 4 in the fixed part. The arming igniter comprises a powder or actuating charge 3a, an ignition charge 3b and electrical circuits 3c. As such electric arming igniters are well-known per se, the constructional details of the igniter 3 will not be described in any detail here, it being sufficient to mention that for a specific activation of the electrical circuits 3c the ignition charge 3b is initiated, whereupon also the actuating charge 3a is initiated. The arming igniter also comprises a lodging member 5 in the form of a pin.This locking pin is arranged in the fixed part 1 in a recess 6 which is connected to the igniter recess 4. The recess 6 is, in this case, made as a through hole between the under surface 1 a of the fixed part 1 and the igniter recess 4. In crosssection the recess or hole 6 is concentric to but smaller than the igniter recess 4.

The movable part 2 is also provided with a recess 7 which is opposite to and aligned with the through hole 6 in the fixed part 1. In the safe position shown in Figure 1, the outer end 5a of the locking pin 5 projects into the recess 7. As shown the locking pin 5 is somewhat tapered at its outer end 5a. In the position illustrated in Figure 1, the locking pin is arranged to lock the movable part 2 to the fixed part 1. The corresponding recess 7 does not extend through the movable part completely, and at its closed end is somewhat inclined.

A so-called acceleration safety device 8 is also arranged between the fixed and movable parts 1 and 2. This acceleration safety device comprises a sliding body 9 in a recess 10 in the movable part 2. The acceleration safety device is suspended in suspension means 11 in the form of a foil or the like which is arranged to yield at a predetermined acceleration so that the sliding body can be moved in the recess 10. The body is connected to a locking member 12 extending into a corresponding recess 1 3 in the fixed part. The locking member 12 and the sliding body 9 are connected by means of a bolt or screw 14 provided with a head 1 4a, which engages the under surface 9a of the sliding body, and a male thread 1 4b screwed into a corresponding female thread in the locking member 12.In the initial or safe position which is indicated in Figure 1, the locking member 12 is located in its recess 13 and the parts 1 and 2 are locked to each other via this safety device.

When the sliding body 9 is subjected to a predetermined level of acceleration the foil or the like yields and the body is moved, which means that the locking member 12 is retracted out of its recess 1 3 so that the parts 1 and 2 are released.

Figure 2 illustrates the case in which the arming igniter has been released, as a result of which the locking pin 5 has been pushed down into the corresponding recess 7. It is important that the entire locking pin 5 should be pushed down into the recess 7 so that the parts 1 and 2 are fully released. As illustrated in Figure 2, the depth of the recess 7 is H 1 and the length of the pin is H2. The depth H1 suitably exceeds H2 by from 1020%. The pin 5 is pushed down into the recess by a comparatively large force under the action of the actuating charge 3a. After the pin 5 has been pushed down into the recess 7 it should be maintained in a distinct position in the recess.

Therefore the inner diameter of the recess 7 is somewhat smaller than the outer diameter of the locking pin 5.

In the illustrated embodiment it has been assumed that the release of the two safety devices 3 and 8 should be carried out in a specific order.

Specifically, the acceleration device 8 should be released before the arming igniter 3. If this does not happen, the locking pin 5 causes the wall between the recesses 7 and 10 to be deformed when it is pushed down into its recess 7. This deformation, indicated at 1 5 in Figure 2, reduces the inner diameter of the recess 10 under the body 9 so that sliding movement of body 9 is prevented when the body is subjected to the predetermined acceleration force. This means that the locking member 12 is not released even if its releasing factor is subsequently applied. If the order of applying the releasing factors to the safety device is correct, however, ie if the acceleration safety device is released before the arming safety device, then the unlocking between the two parts 1 and 2 can be completed.

As illustrated in Figures 1 and 2, the recesses 7 and 10 are arranged at the side of each other so that their longitudinal axes 4a and 7b, respectively, are substantially parallel to each other. It will be apparent, however, that these recesses could have other relative dispositions so that their axes are not parallel to each other in the paper plane as in Figure 2, or in a plane perpendicular to the paper plane.

In Figure 3 the distance between the recesses has been indicated by dimensions "a". As mentioned above, the deformation 1 5 of the material between the recesses is caused by the locking pin 5 entering its recess 7 before the acceleration safety device 8 has been released, as a result of its outer diameter to some extent exceeding the inner diameter owt the recess 7.

Preferably, this difference in diameters is of the order of about 0.1 mm. The rotor and the locking pin can be made, for example, of steel, brass or any other similar alloy.

The safety device of the present invention can also be arranged to cooperate with a rotation safety device. A rotational safety device 1 7 is illustrated in Figure 4 in connection with an ammunition unit, and comprises a leaf spring 1 7a which divides the circular casing 1 6 of the ammunition unit into two segments. The outer ends 1 7a' and 1 7a" of the leaf spring 1 7a are supported in corresponding recesses 1 6a and 16b of the casing 1 6. The central portion of the leaf spring is provided with a body or mass 18 having a part 18a extending into a recess 1 9 formed on the side of a movable part 2', in this case a rotor member.Under the action of a centrifugal force of a predetermined value, due to the rotation Rp of the ammunition unit, the body 1 8 is subjected to a force F so that the leaf spring 1 7a is bent and the part 18a is moved out of its recess 1 9. Then the rotor member is free to be moved by driving means (not shown) in a certain direction, for instance as indicated by the arrow P. The rotational safety device 1 7 should normally be released before an arming safety device comprising a locking pin 5'.If, however, the arming safety device is released before the rotational safety device then the locking pin 5' comes into engagement with said part 1 8a of the body 18 which means that the rotor member 2' ig locked to the casing 1 6 via the rotational safety device even when its specific releasing factor is present. The electric arming igniter in Figure 4 is substantially of the same type as the arming igniter illustrated in Figures 1 and 2. In Figure 4 the locking pin 5' has been pushed into its corresponding recess and has come into engagement with the part 18a, thereby preventing release of the rotational safety device 1 7.

Figures 5 and 6 illustrate a safety arrangement comprising an electric arming igniter of the kind shown in Figures 1 and 2 and an interruptor 19 in the form of an axial safety device. The axial safety device comprises a body 20 and a retaining spring 21 and is arranged in a corresponding recess 22 in a movable section member 2". The body 20 comprises a head 20a and the spring 21 is arranged between a ring 23, which is fixed with respect to the sector member, and the under surface of the head. Under the action of an acceleration force caused by the firing of the ammunition unit from the gun barrel, the body 20 moves in the longitudinal direction of the recess 22 against the action of the spring 21, and as soon as the acceleration ceases the body is moved back to its initial position by means of the spring 21.In its displaced position caused by the acceleration a part 20á extends out from said recess 22 and the ring 23. This extending part 20b is then positioned in a corresponding hole 24 in a member 25 which is fixed with respect to the sector member. The part 20b as well as the hole 24 are formed as truncated cones. As a result, the axial safety device temporarily prevents the sector member 2" from moving with respect to the fixed member 25. Normally the arming safety device 5" should be released after the axial safety device 1 9.

If not, ie if the arming safety device is released before the axial safety device, then the material between the recesses 7" and 22 is deformed in the same way as in the embodiments shown in Figures 1 and 2. Such deformation has been indicated by 15'. In principle the deformation occurs when the body 20 takes its initial position or when the body takes the position under the action of acceleration. In the first-mentioned case, the body is forced by the resulting deformation 15' to move in the longitudinal direction so that the part 20b goes into the recess 24. As the deformation remains the body 20 cannot be pressed back by its spring but remains in the position illustrated in Figure 5, which means that the sector member 2" has been definitely locked to the member 25.When the arming electric igniter is initiated in the gun barrel, ie when the body has been subjected by the acceleration force and moved into the position illustrated in Figure 5, then the body 20 is also prevented from moving back to its initial position by the deformation 1 5'.

In Figures 7, 8 and 9, the function of the axial safety device is illustrated in more detail. In Figure 7 the body 20 assumes its initial position under the action of the spring 21 and in which the part 20b is out of the fixed member 25. During the gun barrel phase as illustrated in Figure 8 the body has been pressed down under the action of the acceleration and against the spring 21 to its other position in which the part 20b extends down into the recess 24 of the fixed part 25. Figure 9 illustrates a position in which the sector member 2" has been locked to the fixed member 25. This locking is then improved by means of inclined side surfaces of the part 20b and the recess 24. It is apparent that the inclined surfaces of different configurations can be used, for instance the surfaces can be made in the form of truncated pyramids instead of truncated cones.

Claims

1. An ammunition unit incorporating a safety arrangement for preventing unintentional movement of a first part of the ammunition unit relative to a second part thereof and comprising first and second safety devices adapted to be released in that order to permit said relative movement of said parts of said ammunition unit, wherein said second safety device comprises a locking member which in its safe position engages one part of the ammunition unit and which, on release of said second safety device is slidingly moved out of engagement with said one part to be received within a recess in the other part of the ammunition unit, and wherein said safety devices are adapted to cooperate whereby movement of said locking member into said recess locks the first safety device against release if said first safety device has not been released prior to said second safety device.

2. Safety means, particularly for an electric arming device (3) which in an ammunition unit (16) in the safe position is arranged to lock a movable part (2), for instance a timing mechanism member such as a rotor, a sector body or the like, to a fixed part (1), for instance the housing of the arming device characterized by a sliding member (5) which is arranged to be pushed into a corresponding recess (7), preferably in the movable part (2), which sliding member (5) comes out of engagement of the fixed part (1) when it is completely pushed into said recess (7) of the movable part (2) so that this part is free to be moved with respect to the fixed part (1); said sliding member (5) when pushed into said recess (7) is arranged to make a deformation (1 5) of the recess wall or deform or lock one or more further safety devices (8 17, 19) of the ammunition unit in such a way that they are prevented from being released if they are subjected by their respective releasing factors in a reversed order with respect to the releasing factor of the first mentioned safety device.

3. Safety means according to Claim 2, characterized in that said recess (7) for the sliding member (5) is located at the side of an adjacent recess (10) for a further safety device and that said deformation (15) caused by the sliding member (5) when pushed into the recess (7) is made in the material between said recesses (7, 10).

4. Safety means according to Claim 3, characterized in that the longitudinal axes (4a, 7b) of said recesses (7, 10) are parallel to each other.

5. Safety means according to Claims 3 or 4, characterized in that said deformation (15) is engaging a further safety device (8) comprising a body (9) which is sensitive to an acceleration force so that said body (9) is prevented from being moved or returned back to its initial position when the releasing order is reversed.

6. Safety means according to Claim 1, characterized in that the recess (7) for the sliding member (5') is extending in an angle, preferably a right angle, with respect to recess (19) for a rotational safety device (17).

7. Safety means according to Claim 6, characterized in that said rotational safety device (17) comprises a body (18) which is attached to a leaf spring (17a) and which is provided with a part (18a) which is extending into said recess (19) and that the sliding member (5') is cooperating with said part (18a).

8. Safety means according to Claim 5, characterized in that said sliding member (5") is locking the acceleration sensitive body (9) in such a position that it is locking the movable part (2") to another fixed part (25) provided with a portion (24) formed with inclined surfaces such as truncated cone surfaces or the like.

9. An ammunition unit incorporating a safety arrangement substantially as hereinbefore described with reference to Figures 1-3, Figure 4 or Figures 5-9 of the accompanying drawings.