AN ARRANGEMENT IN A MINE FUZE

Abstract: An arrangement in a mine fuze (1) intended for a land mine (3) provided with a high explosive charge and intended to be set flush with or below the surface of the ground. The mine fuze includes a firing sequence which comprises a firing pin (25) provided with a firing-pin spring (36), a detonator (23) carried by a detonator case (20) and a booster (26). The mine fuze (1) includes a hydraulic system comprising a movable primary unit, for example a plunger (14), and a movable secondary unit, in the form of the detonator case (20). A pressure sensor (9) is arranged to displace the detonator case (20) from an unarmed state to an armed state, via the hydraulic system. The pressure sensor (9) is in force-transmitting connection, via a fluid-filled bladder, with both the primary unit (14) of the hydraulic system and with the firing-pin spring.

Description: An arrangement in a mine fuze TECHNICAL FIELD The present invention relates to an arrangement in a mine fuze for detonating a high explosive land mine of the kind which may be set flush with or below the surface of the ground, said mine fuze comprising a firing or deton¬ ating sequence (also called "explosive train") which in- eludes a firing pin, a detonator and a booster charge, the firing pin being intended to initiate firing of the booster via the detonator in a manner to ignite the high explosive charge of the mine, and in which device the detonator can be displaced by means of a movable deton- ator case from an unarmed or "safe" state, in which the detonator is removed from the firing sequence, to an armed state in which the detonator is present in said firing sequence. BACKGROUND PRIOR ART In conventional mine fuzes of this kind, the mine is armed solely by mechanical means, by either moving the detonator into the firing sequence and/or by rotating the firing pin into said sequence, for example with the aid of a mechanical timing device, such as a clock mechanism. SUMMARY OF THE INVENTION The object of the present invention is to provide an arrangement of the kind mentioned in the introduction in which arming of the mine fuze device in a conventional, mechanical manner is fully or partially avoided. This reduces the result of a malfunction caused, inter alia, by a faulty mechanical timing mechanism or a faulty spring arrangement, etc. This object is achieved by means of an arrangement ac¬ cording to the invention as characterized in the follow¬ ing Claim 1. Further embodiments of the invention are set forth in the depending Claims. In accordance with the invention the conventional mechan¬ ical components and devices of a conventional mine fuze are replaced with a hydraulic system in which the deton¬ ator case, upon arming, will move into the firing se¬ quence due to the action of a hydraulic fluid, which in response to a pressure sensor will exert force against the detonator case in a manner to cause the same to move to its armed state. Arming of the mine is thus effected in a much more reliable manner than that achieved when using conventional mechanical arming systems. According to a further development of the invention, a pressure sensor is arranged to act on a primary part of the hydraulic system, via a resilient container filled with fluid. The resilient container is arranged to act upon a biasing sleeve or some like device in a manner to bias the firing-pin operating spring at the same time as the detonator is moved into the firing sequence. Conse¬ quently, because the firing-pin spring will be biased at the same time as the detonator is moved into the firing sequence, arming of the mine and initiation of the mine fuze will take place simultaneously. As a result hereof, the mechanical time device, clock mechanism or like device for arming the firing pin can be om itted. BRIEF DESCRIPTION OF THE DRAWING The invention will now be described in more detail with reference to a preferred embodiment thereof illustrated in the accompanying drawing. Figure 1 illustrates a mine fuze for use in antitank mines and provided with an arrangement according to the invention. Figure 2 is a perspective, longitudinal view of a detonator case incorporated in the mine fuze. Figures 3 and 4 illustrate schematically two different positions of the firing pin of the mine fuze in relation to the detonator case. PREFERRED EMBODIMENT OF THE INVENTION Figure 1 illustrates a mine fuze 1 which is firmly con¬ nected to a partially illustrated antitank mine 3 by means of a screw joint 2, the mine 3 incorporating a high explosive charge 4 in a conventional manner. The mine fuze 1 comprises a metallic housing 5 which is provided at the top thereof with a vertically extending, cylindri¬ cal cavity 6, the circular defining edge 7 of which is 'directed radially inwards to t_bme slight extent. Loosely placed in the cavity is a substantially disc-shaped, resilient container which is fully closed and sealed and which in the illustrated embodiment has the form of a plastics bladder 8 filled with fluid, such as water, oil or gas for example. The bladder 8 reaches substantially to the top of the cavity-edge 7, such as to enable a metallic, round cap or cover 9 to be secured between the upper side of the bladder 8 and the cavity-edge 7, in contact with the bladder. The cap 9 functions as a press¬ ure sensor in a manner hereinafter described, and is rigidly connected to a metallic post 10. The post 10 is intended to project some few decimeters above the surface of the ground in which the mine is placed, and is capable of being felled to one side by a moving enemy target, such as a tank or the like, as illustrated by the arrow 11, so as to tilt the cap 9 in the manner illustrated by the arrow 12. Arranged in the bottom of the cavity 6 is a vertically extending, cylindrical recess or chamber 13 which accom¬ modates a movable primary unit, which in the illustrated embodiment has the form of a metallic plunger 14 and which can be acted upon by the bladder 8, the bladder 8 thereby forming a force-transmitting connection (below referred to as a first force-transmitting connection) with the pressure sensor 9. The recess 13 contains hydraulic fluid, for example', oil. The recess 13 communi¬ cates with a horizontally extending channel 16 in the housing 5 of the mine fuze, via a vertical throttling channel 15. The plunger 14 can therewith be moved down¬ wards in the direction of the arrow 18 against the action of a spring 17, while forcing hydraulic fluid through the channel 15 and into the channel 16. Arranged for axial movement in the channel 16, in the direction of arrow 19, in response to the pressure exerted by said hydraulic fluid is a secondary unit, which in the ill-ustrated embodiment has the form of a metallic, substantially cylindrical detonator case 20, cf also Figure 2. The detonator case 20 thereby forms a force-transmitting connection (below referred to as a second force-transmitting connection) with a detonator 23, to be described further below. Both the plunger 14 and the detonator case 20 are sealed from contact with hydraulic fluid by means of a respective 0-ring 21 and 22. The plunger 14 thus forms the movable primary unit and the detonator case 20 forms the movable secondary unit of a hydraulic system, in which the hydraulic fluid transmits force and motion from the cap 9 (the pressure sensor) to the detonator case 20, via the plunger 14. The detonator case 20 has accommodated therein the deton¬ ator 23 which is intended to be brought into a mine det- onating sequence, by means of the case 20, in a manner hereinafter described. To this end the holder 20 is pro¬ vided with a vertical, cylindrical channel 24 intended to guide a firing pin 25 towards the detonator 23. The mine-firing sequence consists of the firing pin 25, the detonator 23 and a booster charge 26 which is posi- tioned beneath the firing pin 25 and intended to detonate the high explosive charge 4 of the mine. A spring 27 is arranged to hold the detonator case 20 in the retarded, unarmed position illustrated in Figure 1, in which posi¬ tion the detonator 23 is out-of line with the firing pin 25 and the booster 26. The detonator case 20 is provided on each side of the detonator 23 with a respective segment-shaped recess 28 and 29, the bottom surfaces of which form a respective vertical guide surface for a firing-pin holder 30. Each of the recesses 28 and 29 merge with a respective semi- segmental recess 31 and 32 in a direction towards that end of the case 20 that is distant from the hydraulic fluid, the recesses 31 and 32 forming horizontal guide surfaces for the firing-pin holder 30. The portion of the detonator case 20 located between the recesses 28 and 29 and between the recesses 31 and 32 respectively thus forms a guide strip 33 which can be straddled by the firing-pin holder 30. To this end, the firing-pin holder 30 has the form of a metallic, vertical cylindrical tube having two mutually opposing recesses 34 provided at its lower end, one of which being shown in Figures 3 - 4, thereby to form a bifurcate holder structure. The reces¬ ses 34 are substantially of the same width as the guide strip 33 and are so formed as to permit the bifurcate holder 30 to straddle the guide strip 33, in a manner clearly shown in Figure 3. The firing-pin holder 30 has a horizontal web plate 35, in which the firing pin is firmly mounted. A firing-pin operating spring 36 is mounted against the upper surface of the web 35 and can be biased by means of a tubular, metallic, vertically arranged, upwardly closed biasing sleeve 37 which is movable downwardly in the direction of the arrow 38. Movement of the biasing sleeve 37 is ar¬ ranged to take place in a vertical, cylindrical passage 39 provided in the housing 5, under the action of the bladder 8 when subjected to pressure from the cap 9. Thus, the bladder 8 forms a force-transmitting connection (below referred to as a third force-transmitting connec¬ tion) between the pressure sensor 9 and the firing-pin spring 36. During transportion of the mine fuze, the biasing sleeve 37 is held in the unarmed state illustrated in Figure 1 by a locking piston 40, which is held in a retarded, unarmed state by a fusing lever 42 against the action of a spring 41. The mine fuze f nctions in the following manner. Subsequent to placing the mine 3 together with the mine fuze 1 in the ground, with the post 10 extending to a suitable level thereabove, the fusing lever is moved out, so that the locking piston 40 is withdrawn by the spring 41, therewith permitting downward movement of the biasing sleeve 37. As soon as the post 10 is deflected to one side, as illustrated by the arrow 11, the cap 9 is tilted downwards, as indicated by the arrow 12. The cap 9 then presses against the bladder 8 which consequently depres¬ ses both the plunger 14 and the biasing sleeve 37. The plunger 14 therewith forces hydraulic fluid from the cavity 13 down towards the detonator case 20, causing the case to move the detonator 23 in the direction of arrow 19, until the detonator registers with the firing pin 25 and the booster 26, i.e. until the detonator is brought into the firing sequence of the mine fuze. The biasing sleeve 37 will bias the firing-pin spring 36 at the same time. During movement of the detonator case 20 to the right in Figure 1, i.e. in the direction of arrow 19, the firing- pin holder 30 slides against the horizontal guide sur¬ faces 31 and 32 on the detonator holder 20. When the de- tonator case 20 has been moved by the hydraulic fluid to an extent such that the detonator 23 will be located in the firing sequence, the recesses 23 and 29 will be located opposite the firing-pin holder 30, thereby enabling the holder 30, which in this position has been biased by the firing-pin spring 36, to move downwardly with an impact force such as to enable the firing pin 25 to penetrate the detonator 23, in the manner illustrated in Figure 4, such that the detonator will be ignited which in sequence will initiate the booster, thereby actuating the high explosive 4. Although the secondary unit of the illustrated hydraulic system comprises the detonator case 20 itself, i.t will be understood that the hydraulic fluid may, alternatively, be caused to act indirectly on the detonator case 20 via a hydraulic secondary unit in the form of a piston (not shown) .

Claims: Claims 1. An arrangement in a mine fuze (1) intended for a land mine (3) having a high explosive charge (4), the mine fuze comprising a firing sequence which includes a firing pin (25), a detonator (23) and a booster (26), and in which the firing pin is able to initiate firing of the booster via the detonator in a manner to ignite the high explosive charge of the mine, and in which the detonator can be displaced by means of a movable detonator case (20) from an unarmed state, in which the detonator is moved out of the firing sequence, to an armed state in which the detonator is present in said sequence, c h a r a c t e r i z e d in that the mine fuze (1) incorporates a hydraulic system comprising a movable primary unit and a movable secondary unit between which hydraulic fluid is arranged to transmit force and motion from the primary unit to the secondary unit, the primary unit being in a first force-transmitting connection with a pressure sensor (9) arranged in the mine fuze and ope¬ rative to detect pressure exerted on the mine,, and the secondary unit being in a second force-transmitting con¬ nection with the detonator (23). 2. An arrangement according to Claim 1, c h a r a c t e r i z e d in that the pressure sensor (9) is in a third force-transmitting connection with a firing-pin spring (36), and capable of biasing the firing-pin spring in response to said pressure against the mine. 3. An arrangement according to Claim 2, c h a r a c t e r i z e d in that the pressure sensor (9) is in said third force-transmitting connection with the firing-pin spring (36) via a resilient container (8) filled with a fluid. 4. An arrangement according to Claim 1, c h a r a c t e r i z e d in that said first force- transmitting connection between the pressure sensor (9) and the primary unit (14) is arranged to be effected by a resilient container (8) filled with a fluid.

Inventors: ARNELL CLAES, RISBERG STIG, ARNELL, CLAES, RISBERG, STIG
Applicants: AFFARSVERKET FFV, AFFAERSVERKET FFV
Application year: 1986
Main classification: F42B23
IPC codes: F42C7