A safety device for arming a mine

Abstract

 The device (1) comprises an initiator element (6) movable between a safety position and a position in which it can be activated by an actuator element (2); the movement of the initiator element (6) is controlled by timing means (35, 39), and can take place only after voluntary disactivation, in a predetermined order, of two stop elements (51, 61) for the timing means (35, 39) and for the movement of the initiator element (6) respectively.

Description

[0001] The present invention relates to a safety device for arming a mine.

[0002] Mine arming devices of known type generally comprise an initiator element containing an auxiliary charge operable to trigger the explosion of a main charge when the initiator element is activated by a suitable actuator, and safety means operable to prevent accidental activation of the initiator element by the actuator, which must be voluntarily disactivated by an operator.

[0003] Such devices, however, do not guarantee total safety when the mine has already been primed (that is to say, provided with the initiator element), even if the arming of the mine itself has not taken place (that is to say the voluntary disactivation of the safety means). In fact, the initiator element can be activated even by an accidental shock, and thus cause explosion of the main charge.

[0004] Consequently, mines provided with arming devices of the type described above cannot be transported already primed, but must be primed at the moment of placement. This requires relatively long placement times and the presence of an operator at the location of placement; moreover, it does not guarantee a safety time for the withdrawl of the operator after arming the mine.

[0005] The object of the present invention is the provision of a safety device for arming a mine, which will be free from the disadvantages associated with known devices and described above.

[0006] The said object is achieved with the present invention in that it relates to a device for arming a mine, of the type comprising:
an actuator element disposed on an outer body of the said mine;
an initiator element provided with an auxiliary charge, which can be activated by the said actuator element to trigger explosion of a main charge contained in the said outer body;
timing means for determining a delay time between arming and explosion of the said mine; and
safety means operable to prevent accidental explosion of the said mine;
characterised by the fact that the said initiator element is movable between a first position in which it faces a portion of the said outer body of sufficient thickness as not to be pierced by the effect of the explosion of the said auxiliary charge, and a second position in which the said initiator element is aligned with corresponding holes of the said outer body and facing the said actuator element; displacement between the said first position and the said second position being controlled by the said timing means.

[0007] For a better understanding of the present invention a preferred embodiment is described hereinbelow purely by way of non-limitative example and with reference to the attached drawings, in which:

Figure 1 is a plan view of a device for arming a mine, formed according to the principles of the present invention;

Figures 2, 3 and 4 are plan views of the device of Figure 1 in different operating configurations;

Figures 5, 6 and 7 are respectively, a plan view from above, a partially sectioned side view and a plan view from below of a detail of Figure 1;

Figure 8, 9 and 10 are, respectively, a front view, a plan view, and a rear view of a second detail of Figure 1;

Figures 11 and 12 are, respectively, a side view and a plan view of a third detail of Figure 1; and

Figures 13, 14 and 15 are sections of the detail of Figures 11 and 12, respectively taken on the planes XIII-XIII, XIV-XIV and XV-XV of Figure 12.

[0008] With particular reference to Figure 1, a safety device for arming a mine is generally indicated with the reference numeral 1.

[0009] This device 1 comprises an actuator element 2 disposed on an outer body 3 of the mine and provided with a casing 4 and a piston 5 normally housed in the casing 4 and able to projec t out from it following a convenient command of conventional type.

[0010] The device 1 further includes an initiator element 6 containing an auxiliary charge the explosion of which causes activation of a main charge contained in the body 3 of the mine. The initiator element 6 is of substantially parallelepiped form and is housed in a corresponding seat 7 of a support element or casing 8.

[0011] This casing 8, illustrated in detail in Figures 8, 9 and 10, comprises a containment body 9 formed by three walls 10, 11, 12 disposed substantially in a C-shape and defining within their interior the seat 7 for the initiator element 6. The walls 10 and 12 are of greater length than the wall 11, face one another and are joined by two reinforcing lower cross pieces 13. The wall 12 has a substantially rectangular slot 14 formed along its upper edge 15.

[0012] The casing 8 further includes a hollow cylindrical body 20 engaged by a fixed pin 21 of the outer body 3 of the mine; this cylindrical body 20 is integrally connected by means of a rib 22, obliquely disposed with respect to the containment body 9, to an outer corner 23 common to the walls 11, 12 of the containment body 9. From a lower edge 24 of the wall 12 extends, outwardly of the containment body 9, a flat surface 25 of polygonal outline integrally connected to the rib 22; this flat surface 25 has a projecting portion 26 on a rounded end 27 of which is disposed an upwardly facing tooth 28 provided, on the side opposite the rib 22 with a concave seat 29 in the form of an acute dihedral with a vertical corner.

[0013] A second flat horizontal surface 30, which extends from an upper portion of the cylindrical body 20 towards the containment body 9, has a trapezoidal tooth 31 extending in a direction substantially orthogonal with respect to the rib 22 on the same side as the said flat surface 25.

[0014] This tooth 31 is able to cooperate with a cam element 35 rotatable about a central pin 36 and rotationally coupled by gears 37, 38 to a timer clock 39 of conventional type.

[0015] As is clearly visible in Figures from 11 to 15, the cam element 35 includes, in a single piece, the said gear 38 and a cylindrical element 40 on which are formed, along an annular intermediate face and in positions diametrically opposite from one another, a slot 41 of concave profile and a tangential depression 42 of semicircular section delimited by a flat radially extending wall 43. The cylindrical element 40 further has, on its annular face opposite the said gear 38, a cam profile 44 constituted by an intermediate cylindrical portion 45 having a smaller diameter than that of the cylindrical element 40 itself and lying between a flat wall 46 tangential to it and a radial flat wall 47.

[0016] As is illustrated in Figure 1, the tangential depression 42 is engaged by one end 50 of a rod 51. This rod 51 is constrained to slide axially by a guide 52 disposed in a tangential direction with respect to the cam element 35, and is controlled at its opposite end 53 by a first safety knob 54; in particular, the end 53 of the rod 51 is provided with an oblong slot 55 engaged slidably by a pin 56 disposed in an eccentric position on the knob 54.

[0017] The casing 8 is urged in an anti-clockwise sense about the fixed pin 21 by a spring cap 57 urged by a coil spring 58 and acting on the casing 8 close to the corner 23 in such a way that the tooth 31 is found in contact with the end 50 of the rod 51.

[0018] The device 1 further includes a safety element 61 rotatable about a pin 62 fixed on the outer body 3, and illustrated in detail in Figures 5, 6 and 7. This safety element 61 includes a hollow cylinder 63 provided with a through hole 64 engaged by the said pin 62, and two substantially parallel arms 65, 66 of elongate form, which extend in an orthogonal direction with respect to the axis of the cylinder 63 starting from opposite ends of the cylinder 63 itself.

[0019] The upper arm 65 has a through hole 67 and a terminal pro jection 68 extending from a lateral edge 69 of the arm 65 itself; this projection 68 has a width decreasing towards its end 70 provided with a downwardly facing tooth 71. The lower arm 66 has a similar structure, with a terminal projection 72 extending from an opposite lateral edge 73 of the arm 66; this projection 72 is of constant width and is provided with a terminal tooth 74 facing outwardly of the safety element 61.

[0020] The safety element 61 is controlled by a second safety knob 75, via a rod 76 connected at one end to an eccentric pin 77 of the knob 75, and at an opposite end to the safety element 61 by means of a pin 78 which engages the said hole 67.

[0021] The operation of the device 1 is as follows.

[0022] Figure 1 illustrates a rest condition of the device 1 in which the position of the casing 8, constrained as mentioned by the spring cap 57 against the rod 51, is such as to maintain the initiator element 6 on a portion of the outer body 3 the thickness of which is sufficient not to be perforated by the said striker elements in the case of accidental activation of the initiator element 6.

[0023] Arming of the mine is effected by turning the first knob 54 in an anti-clockwise sense and the second knob 75 in a clockwise sense in that order; if by mistake, as illustrated in broken outline in Figure 1, the second knob 75 is turned first, the safety element 61 can only perform a smaller rotation in a clockwise sense about the pin 62, because the tooth 71 engages the corresponding seat 29 of the tooth 28 of the casing 8.

[0024] Figures 2 and 3 illustrate subsequent stages in the correct arming of the mine. By rotating the first knob 54 the shaft 51 is displaced towards the right of the pin 55 and disengages from the depression 42 of the cam element 35 which is therefore driven to rotate by the clock 39 via the pair of gears 37, 38. The casing 8, which is thus left free, instantly performs a reduced rotation in the anti-clockwise sense under the action of the spring 58 until the tooth 31 of the casing 8 arrives in contact with the profile of the cam element 35.

[0025] The rotation (in anti-clockwise sense) of the cam element 35 has no effect on the position of the casing 8 until a time has passed sufficient for the slot 41 of the cam element 35 to be engaged by the tooth 31; however, so that this can take place, it is necessary to act on the second knob 75 to cause a clockwise rotation of the safety element 61 as illustrated by the broken outline arrows in Figure 2. It is observed that the snap rotation of the casing 8 described above moves the tooth 28 downwardly and permits the passage of the tooth 71, during actuation of the second knob 75: the said broken lines in Figure 2 indicate for greater clarity the limits of the space occupied by the tooth 71 in its path corresponding to this movement.

[0026] When the tooth 31 of the casing 8 engages the slot 41 it starts a gradual rotation of the casing 8 under the thrust of the spring 58; the casing 8 itself, by acting with its wall 12 on the upper arm 65 of the safety element 61, maintains the tooth 74 at the end of the lower arm 66 in contact with the profile 44 of the cam element 35. When the radial wall 47 of the cam profile 44 comes into contact with the terminal tooth 74 the timer stops and, as illustrated in Figure 3, the initiator element 6 is found in alignment with the actuator 2 and can be activated. In this position the striker elements are located facing respective holes (not illustrated) of the outer body 3, and therefore the mine can explode.

[0027] In Figure 4 there is illustrated the condition of intervention of the safety element 61, which takes place when the second handle 75 is turned in the case of breakdown of the timer 39 and consequent too rapid alignment of the casing 8, or else when, by an erroneous actuation, only the first knob 54 is turned; in both situations the casing starts to rotate under the thrust of the spring 58, but the tooth 71 of the safety element 61 engages the slot 14 on the wall 12 of the casing 8 preventing further rotation of the casing 8 itself. It is further observed that this also prevents a subsequent rotation of the second handle 75, thereby avoiding rapid and therefore dangerous arming of the mine, in that a part of the travel of the timer 39 has already been effected.

[0028] Disactivation of the mine takes place by rotating the second knob 75 in an anti-clockwise sense in such a way as to displace the casing from the operative position illustrated in Figure 3 to the disactivated position illustrated in Figure 4.

[0029] From a study of the characteristics of the device 1 formed according to the present invention the advantages which it allows to be obtained are evident. First of all, it is observed that the mine cannot explode by accidental activation of the initiator element 6 if this latter is not located in the condition of alignment between the striker elements and corresponding holes on the outer body 3; this allows the mine to be transported primed, the placement times to be shortened and possibly the placement to be automated. Moreover, the said condition of alignment can occur only by the dis activation in a predetermined order of two different safety systems. Finally when correct arming has been effected, there is in any case a minimum time (until achievement of the alignment condition) for withdrawal in safety.

[0030] Finally, it is clear that the device 1 described can have modifications and variations introduced thereto without by this departing from the protective ambit of the present invention.

Claims

1. A device for arming a mine, of the type comprising:
an actuator element disposed on an outer body of the said mine;
an initiator element provided with an auxiliary charge, which can be activated by the said actuator element to trigger the explosion of a main charge contained in the said outer body;
timing means for determining a delay time between arming and explosion of the said mine; and
safety means operable to prevent an accidental explosion of the said mine;
characterised by the fact that the said initiator element (6) is movable between a first position in which it faces a portion of the said outer body of sufficient thickness not to be pierced by the effect of the explosion of the said auxiliary charge, and a second position in which the said initiator element (6) is aligned with corresponding holes of the said outer body (3) and faces the said actuator element (2); displacement between the said first position and the said second position being controlled by the said timing means (35, 39).

2. A device according to Claim 1, characterised by the fact that the said safety means include a first stop element (51) of the said timing means (35, 39).

3. A device according to Claim 1 or Claim 2, characterised by the fact that the said safety means include a second stop element (61) operable to interrupt displacement of the said initiator element (6) between the said first position and the said second position.

4. A device according to any preceding Claim, characterised by the fact that the said timing means include a timer clock (39) and a rotating cam element (35) coupled for rotation with the said timer clock (39) and cooperating with a body (31) fixed to the said initiator element (6).

5. A device according to Claim 4, characterised by the fact that the said initiator element (6) is housed in the corresponding seat (7) of a casing (8) which is rotatable with respect to a fixed pin (21); the said body fixed to the said initiator element being constituted by a projecting portion (31) of the said casing (8).

6. A device according to Claim 5, characterised by the fact that the said first stop element is a rod (51) able to engage with its end (50) a corresponding seat of the said cam element (35).

7. A device according to Claim 6, c haracterised by the fact that the said end (50) of the said rod (51) cooperates with the said projecting portion (31) of the said casing (8) to space the said projecting portion (31) from the said cam element.

8. A device according to Claim 6 or 7, characterised by the fact that the said rod (51) is constrained to slide axially along a guide (52) disposed in a tangential direction with respect to the said cam element (35).

9. A device according to any of Claims from 6 to 8, characterised by the fact that the said rod (51) is controlled by a first knob (54).

10. A device according to any of Claims from 6 to 9, characterised by the fact that it includes resilient means (58) which maintain the said casing (8) in contact with the said end (50) of the said rod (51) or with the said cam element (35).

11. A device according to any of Claims from 3 to 10, characterised by the fact that the said second stop element (61) can turn about a fixed pin (62) between a first position in which it can intercept the said casing (8) and a second position in which it cooperates with the said cam element (35).

12. A device according to Claim 11, characterised by the fact that it includes a second knob (75) coupled to the said second stop element (61) for rotation therewith.

13. A device according to Claim 12, characterised by the fact that it includes a rod (76) connected at one end to an eccentric pin (77) of the said second knob (75) and at its opposite end to the said second stop element (71) by means of a cylindrical coupling (67, 78).

14. A device according to any of Claims from 11 to 13, characterised by the fact that the said second stop element (61) includes a tooth (71) which can engage a corresponding seat (14) of the said casing (8) when the said second stop element (61) is located in its first position and the said casing (8) is displaced from its first to its second position; the same tooth (71) being able to engage a further seat (29) of the said casing (8) when the said casing (8) is located in its first position and the said second stop element (61) is displaced between its said first position and its said second position.

15. A device according to any of Claims 11 to 14, characterised by the fact that the said second stop element (61) includes a second tooth (74) able to cooperate with a corresponding profile (44) of the said cam element (35) to stop the said cam element (35) when the said second stop element (61) is located in its said second position.

Drawing