LAND MINE HAVING TIMED IGNITION MEANS

Abstract: There is provided a landmine which comprises a casing, an ignition means (25), a de-masking charge (23), a detonator charge (24) and an explosive charge (26). The ignition means (25) comprises an electronic timing unit (28), an electric motor (20) and an operating shaft (30) which can be locked mechanically by two safety means (11, 12) in a first angular safe position and is driven by the motor (20) via a transmission gear and which allows activation of the de-masking charge (23) and the detonator charge (24) in a second angular live position. The speed of the motor (20) exceeds 5000 r.p.m. and is preferably 15000 r.p.m., while the speed at which the operating shaft rotates is of the order of 1/40 r.p.m. When the mine has not exploded within a given time period, the electronic timing unit (28) restarts the motor (20) for rotation of the operating shaft (30) into a third angular re-safe position, which can be identical to its first angular position. During its rotation, the operating shaft (30) can also activate one of the safety means (11, 12) for locking shaft rotation, and means for marking on the mine the condition of the mine, i.e. whether the mine is safe or live, and for marking above the ground the position of the mine in its re-safe state.

Description: A Mine TECHNICAL FIELD The present invention relates to a mine of the kind which includes a casing, and ignition means, a de-masking charge, a detonator charge and an explosive charge contained in said casing. The ignition means includes divers means required for the intended function of the mine under predetermined conditions. The de-masking charge is intended to blow away part of the mine (the upper part) subsequent to the detection of, for example, an enemy vehicle, but prior to causing the mine to explode. The detonator charge is intended for the preparation of the actual explosion. The explosive charge creates the explosion for destroying the enemy vehicle. BACKGROUND ART Many different embodiments of mines of the kind described in the aforegoing are known to the art. Known to the art are mines having ignition means which include a clock movement for operating a mechanism in accordance with a given program. The mines are provided with safety means to ensure against premature explosion or to prevent the mines from exploding subsequent to a given lapse of time, etc. It has been found, however, that the drive means (the clock movement) are able to function in a manner not intended (e.g. as a result of racing), and that, for some reason or another, the safety means have not functioned correctly or have not been handled in the manner intended, and hence the risk of such mines exploding in a non-planned manner is too great to be accepted. DISCLOSURE OF THE INVENTION The object of the present invention is to eliminate the aforementioned disadvantages and to increase therewith the safety of mines of the described kind. A mine constructed in accordance with the invention includes an electric motor which is driven by an energy source and which is arranged to rotate at a speed exceeding 5000 r.p.m. and to activate the de-masking charge and the detonator charge at given pre-determined external conditions, via a transmission means and an operating shaft. These and other characteristic features of a mine constructed in accordance with the invention are disclosed in the accompanying claims. SHORT DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 illustrates in plan view a mine according to the invention; Figure 2 is a sectional view of the mine illustrated in Figure 1; Figure 3 illustrates two safety means and an operating shaft which is capable of being activated by said safety means and which is arranged to enable activation of the de-masking charge and the detonator charge incorporated in the mine; and Figure 4 illustrates the operating shaft and a marking means whichisactuatableby the operating shaft. PREFERRED EMBODIMENT Figure 1 illustrates in plan view a mine constructed in accordance with the invention, said mine having a casing 10 which contains an ignition means, a de-masking charge, a detonator charge and an explosive charge. For the purpose of rendering the mine safe and live respectively, there are provided two safety means 11, 12 which, during storage of the mine and the transportation thereof, etc., are locked in a safe position by means of a transport safety means 13, which, in turn, is held in place by a metal wire 14. The safety means 11 is prevented from rotating clockwise by an edge 131 on the transport safety means 13, while an edge 132 prevents clockwise rotation of the safety means 12 in a corresponding manner. The knob or handle of respective safety means points towards markings illustrated by horizontal sectioning in the drawing ("green"), showing that the mine has been made safe. This marking is also shown in a window 15 arranged in the lid of the mine. When the mine is safe, the safety means 11, 12 prevent an operating shaft 30 from rotating (see Figure 3). Before placing the mine in the ground, the mine must be made live. This is effected by removing the metal wire 14 and the transport safety means 13, whereafter the safety means 11, 12 are depressed and turned clockwise through 900. The knob or handle of the safety means will then point towards markings having vertical sectioning in the drawing ("red"), showing that the mine is live. The marking visible in the window 15, however, is still sectioned horisontally ("green"). When the safety means 11, 12 occupy their non-safe position, a current path is connected to an electric motor 20 incorporated in the mine (see Figure 2). At the same time a current path is connected to an electronic unit which includes a timing device and after a lapse of about 10 minutes connects a current path to the ignition means. Also, the operating shaft 30 is mechanically freed, see Figure 3, said shaft 30 being driven by the electric motor and thus begins to rotate as soon as the safety means 11, 12 take their non-safe position. The motor 20 is arranged to rotate at a relatively high speed, e.g. a speed of about 15000 r.p.m., and drives the operating shaft 30 via a transmission means at a transmission ratio of 600000:1. After a lapse of about 10 minutes, the shaft 30 will have rotated through about 900. In this position, two bores extending through the shaft 30 at right angles to the long axis of said shaft will adopt positions such that one bore enables detonation of the de-masking charge while the other bore enables detonation of the detonator charge. These charges, however, can only be detonated when a magnetic sensor incorporated in the mine detects, in a known manner, the presence of an enemy vehicle, such as a tank. As the shaft 30 rotates, it turns a marking shaft which exhibits at one end thereof a marking which can be seen through the window 15. As previously mentioned, this marking has the form of horisontal sectional lines ("green"), when the mine is safe, and vertical section lines ("red"), when the shaft 30 has been rotated through said 900 after a lapse of 10 minutes. The sectional view shown in Figure 2 illustrates the casing 10, a casing lid 21, a battery 22 for operating the electrical motor 20, the de-masking charge 23, the detonator charge 24, the magnetic sensor 27, the ignition means 25 and the explosive charge 26. The transport safety means 13-and the safety means 11 are shown arranged on the lid 21. As previously mentioned, Figure 3 illustrates the manner in which the safety means 11, 12 prevent rotation of the operating shaft 30. As will be seen, these safety means in the safe position both engage recesses in the shaft 30. Thus, even though the motor shbuld be energized and therewith activated for rotation of the shaft 30, the shaft is unable to rotate before both safety means have been mechanically moved from the safe position. After a time lapse of about 10 minutes subsequent to rendering the mine live, the mine will thus be ready to be exploded. Meanwhile the timing means in the electronic unit is operative, and if the mine has not been caused to explode within a period of 30 days, a further current circuit is connected to the motor 20, which then begins to rotate the operating shaft through 2700, back to the starting position. The two bores arranged in the shaft 30 will then be rotated out of the positions necessary for effecting a detonation, i.e. the detonator charge and the de-masking charge can not now be detonated. In addition hereto, one of the safety means 11, 12 will be lifted by the shaft 30 in a manner such that said safety means, subsequent to the shaft 30 being rotated through a complete turn, will prevent the shaft 30 from being rotated through a further revolution before the safety means has been reset. The safe, green marking will now be shown in the window 15. Rotation of the operating shaft 30 after said lapse of 30 days also causes an activating means 40, see Figure 4, to be displaced in a manner such as to activate a marking means (not shown in Figure 4) arranged to mark above the surface of the ground the position of the mine beneath said surface. Figure 4 illustrates the position of the shaft 30 10 minutes after the mine has been made live and buried in the ground. A stop screw 41 extends vertically downwardly and projects slightly outside the shaft. When the shaft 30 is rotated through 2700 to its starting position after the aforementioned lapse of 30 days, the stop screw 41 during its rotation will engage the edge of the activating means 40, which in the illustrated embodiment comprises a springactuated ignition plug. The spring is tensioned during movement of the ignition plug to the right, and, at the same time, a protective cover plate 42 is rotated out of the illustrated position, in which it covers an opening 43 intended for the passage of the ignition plug. Upon continued rotation of the shaft 30, the mechanical contact of the stop screw 41 with the ignition plug 40 ceases, therewith releasing and igniting the marking means on the other side of the opening 43. This means, which comprises a charge and a "flag" fixed to a line at the mine casing is therewith shot through the layer of earth above the mine, to disclose the position of the mine. The mine, which is now safe, can be lifted from the ground without risk, thereafter the safety means 11, 12 are rotated to the starting position ("green"). Subsequent to changing the battery 22 and the marking means, the mine is again ready for renewal burial in the earth. The speed of the motor 20 should not be less than 5000 r.p.m. or greater than 200000 r.p.m. Figure 2 also illustrates the two bores 301 and 302 of the operating shaft 30, and the electronic unit 28. Adjacent the bore 302 is a detonating cap which is arranged to detonate the de-masking charge which, in turn, initiates detonation of the detonator charge through a delay capsule in the ignition means 25.

Claims: Claims: 1. A mine comprising a casing, containing an explosive charge (26), a detonator charge (24), a de-masking charge (23), and an ignition means (25) with an electric motor (20) and timing means, characterized in that the electric motor (20) is arranged to rotate at a speed exceeding 5000 r.p.m. and to enable detonation of the de-masking charge and the detonator charge at given, pre-determined external conditions, and in that the timing means is arranged to control the electric motor (20) in a manner such a) that the motor is caused to start and to operate during a given first time period until the shaft (30) has been rotated to an angular position necessary for said detonation of the de-masking charge (23) and the detonator charge (14), whereafter the motor is stopped, b) that in the event of the mine not being exploded, the motor, after a given second time period, is caused to restart and to operate until the shaft (30) has been rotated to an angular position which lies completely out of the detonating position of the shaft, and c) as to actuate then marking means arranged to mark above the surface of the ground the position of the mine beneath said surface. 2. A mine according to claim 1, characterized in that the motor (20) is arranged to rotate at a speed beneath 20000 r.p.m. and preferably at a speed of approximately 15000 r.p.m. 3. A mine according to claim 1 or claim 2, characterized in that there are provided two externally, mechanically actuatable safety means (11, 12) which when occupying their safe position prevent the operating shaft (30) from being rotated. 4. A mine according to claim 1, characterized in that arranged in the operating shaft (30) are two bores which extend at right angles to the long axis of the shaft, of which bores one in said given position of the operating shaft (30) enables detonation of the de-masking charge (23), while the other bore enables detonation of the detonator charge (24). 5. A mine according to claim 1 characterized in that the timing means is arranged to control the motor (20) after the two safety means (11, 12) have been moved from their safe position. 6. A mine according to claim 1, characterized in that the activating means comprises a body which is connected to the mine by means of a line and which can be propelled upwardly by means of an explosive charge. 7. A mine according to claim 1, characterized in that the operating shaft (30) is arranged, subsequent to continued rotation of said shaft after being displaced from said first given position, to also activate one of the two safety means (11, 12) to a safe position, thereby ensuring that the operating shaft (30) can not be caused to commence a further turn before the safety means (11, 12) have again been mechanically activated. 8. A mine according to claim 1, characterized in that the operating shaft (30) is arranged to rotate a marking shaft which has markings at one end thereof, said mine being provided with a window (15) through which one of said markings can be seen, said marking showing whether the mine is safe or live.

Inventors: ARNELL, CLAES GORAN, Arnell, Claes Göran
Applicants: FORENADE FABRIKSVERKEN
Application year: 1980
Main classification: F42C15
IPC codes: F42C15