Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F42—AMMUNITION; BLASTING
  • F42C—AMMUNITION FUZES; ARMING OR SAFETY MEANS THEREFOR
  • F42C11/00—Electric fuzes
  • F42C11/001—Electric circuits for fuzes characterised by the ammunition class or type
  • F42C11/007—Electric circuits for fuzes characterised by the ammunition class or type for land mines

Definitions

• the field of the present invention is that of devices allowing the detection of an objective by means of a trap wire.
• Such devices can be associated with a mine of the anti-personnel or anti-vehicle type.
• Trap wires are known which are placed manually on the ground during the laying of the mine.
• wires must be attached to a point distant from the mine in order to be tensioned. A traction exerted on the wire or the rupture of this one causes the release of a striker which initiates the explosive of the mine.
• Patent FR2406180 describes such a device.
• a shell, a rocket or a disperser mounted on a vehicle for example, a shell, a rocket or a disperser mounted on a vehicle.
• the initiation device associated with the wire is complex and expensive mechanics and it does not make it possible to discriminate the types of objectives.
• Trap wires are also known which consist of flexible conductors intended to be broken by the objective.
• the rupture is detected by the mine electronics due to the resulting variation in the electrical resistance of the wires.
• wires have the main disadvantage of being fragile. Automatic dispersion of the wires by pyrotechnic means (for example with the means described by patent FR2677750) risks causing them to break, thus making the mine completely ineffective.
• Such wire traps are generally reserved for anti-tank mines.
• the invention proposes a rustic device, inexpensive and the installation of which can be carried out automatically by the mine itself.
• This device nevertheless has an excellent level of reliability and allows recognition of the objective.
• the subject of the invention is a device for detecting a target, in particular for triggering the firing of a mine, and comprising a trap wire intended to be moved by the target and means for processing a information provided by the movement of the trap wire, device characterized in that the processing means comprise on the one hand an element integral with the trap wire and capable of translating and / or deforming with respect to a fixed support when the trap wire is moved, and on the other hand means for detecting the displacement and / or the deformation of the element relative to the support.
• the element integral with the trap wire comprises a permanent magnet and the means for detecting the displacement of this element consist of a contactor having at least two magnetic strips, contactor integral with the support and disposed near the 'magnet.
• the support could then advantageously be secured to the mine.
• the element integral with the trap wire comprises a contactor having at least two magnetic strips, and the means for detecting the displacement of this element comprise at minus a permanent magnet secured to the support and disposed near the contactor.
• the support will then take the form of a cylindrical case, the contactor being integral with a ring mounted sliding inside the case and the magnet will have a bore inside which will be likely to penetrate the contactor during displacement of the trap wire.
• the contactor is made integral with the ring by means of a resin.
• the element integral with the trap wire is a plate, one end of which is fixed on the support, plate on which a strain gauge is fixed, the means for detecting the deformation of this element comprising electronics allowing the measurement of the forces received by the gauge during the displacement of the trap wire.
• the support may consist of a counterweight which is ejected or placed at a distance from the mine.
• the device may include a compression spring disposed between the element secured to the trap wire and the support.
• the device may also include damping means arranged between the element integral with the trap wire and the support.
• damping means will preferably be constituted by a spring made of shape memory material.
• the element integral with the trap wire comprises a deformable membrane carrying at least one conductive surface and the displacement detection means comprise an electrical circuit integral with the support, and comprising at least one part on which the membrane is applied at rest so as to close the circuit by means of its conductive surface and from which it is separated during its deformation, thus opening the electrical circuit.
• the deformable membrane comprises a central part on which the trap wire is fixed and a peripheral part secured to the support, the central and peripheral parts being separated by at least one thinned zone allowing the deformation.
• the membrane will preferably be made of an electrically conductive material.
• the electrical circuit can be produced on a plate using the printed circuit technique.
• the support may be constituted by a counterweight which is ejected or placed at a distance from the mine, and the trap wire may comprise a pair of conductors which pass through the membrane and the ends of which are soldered to the electrical circuit.
• the trap wire will advantageously be made integral with the membrane by overmolding or bonding.
• FIG. 1 diagrammatically represents an anti-personnel mine placed on the ground and comprising four trap wires according to the invention
• FIG. 2 represents in axial section a detection device according to a first embodiment of the invention
• FIG. 3 represents in axial section a detection device according to a second embodiment of the invention
• FIG. 4 represents in axial section a detection device according to a third embodiment of the invention
• FIG. 5 represents in axial section a detection device according to a fourth embodiment of the invention.
• FIG. 6 represents in axial section a detection device according to a fifth embodiment of the invention.
• FIG. 6a shows the face of the support plate of the electrical circuit on which the membrane is in contact
• FIG. 7 represents in axial section a detection device according to a sixth embodiment of the invention.
• a mine 1 of the anti-personnel type is placed on the ground by a dispersing means, not shown (shell, rocket or disperser mounted on the vehicle).
• the trap wire is connected to a processing electronics 4 placed in the mine.
• a displacement of the trap wire is taken into account by a detection device which causes the initiation of the mine.
• Figure 2 shows in axial section a first embodiment of a detection device ' according to the invention.
• the detection device comprises a trap wire 3 which here consists of a pair of conductors connected to the processing electronics 4.
• the trap wire 3 penetrates inside the counterweight 2 which constitutes a substantially cylindrical housing made of stainless steel for example.
• a ring 5 is mounted with a sliding adjustment in the internal bore 6 of the housing constituting the counterweight 2.
• This ring 5 carries a contactor 7 having at least two magnetic strips 7a, 7b arranged in a glass bulb.
• the output terminals 8a and 8b of the contactor 7 are fixed to a printed circuit 9 which ensures their connection to the conductors of the trap wire 3.
• the contactor 7 and the ring 5 are joined together by filling 10 with a polymerizable resin of the epoxy or polyurethane type (such as, for example, the RE7710 resin from the company Hexcel).
• a polymerizable resin of the epoxy or polyurethane type such as, for example, the RE7710 resin from the company Hexcel.
• Magnetic strip contactors are readily available commercially. They are used for example in household appliances. They have magnetic strips which open or close a contact when the contactor is approached to a permanent magnet.
• a permanent magnet 11 of annular shape and having a bore 19 is made integral with the body of the counterweight 2 by means of an annular crimp 12.
• a compression spring 13 is placed between the magnet 11 and the ring 5, it maintains the ring 5 at a distance from the magnet 11.
• the printed circuit 9 then comes to bear on the magnet 11 and acts as a stop for a mobile element constituted by the ring 5 carrying the contactor 7 and the printed circuit 9.
• a second spring 14 is also disposed between the magnet 11 and the ring 5, this spring is made of a shape memory material and acts as a vibration damper of the movable element relative to the support constituted by the body the flyweight 2 carrying the magnet 11.
• shape memory materials have interesting damping properties. It is therefore possible to make a spring made of such a material play a role of damper of mechanical vibrations.
• Titanium / Nickel type or of the Copper / Zinc / Aluminum type. These materials are available, for example, from Raychem or Imago companies.
• a spacer 15 is supported on the magnet 11, it provides a holding surface for a rubber cover 16 which seals at the level of the passage of the trap wire 3.
• a fold 17 of the body of the counterweight 2 maintains the sealing cap 16 on the spacer * by pinching.
• the spacer 15. also has a flange 18 which constitutes an axial stop for the printed circuit 9.
• the mounting of the device is carried out as follows:
• the contactor 7 is first of all made integral with the ring 5 by means of the filling 10.
• a tool will be used which makes it possible to maintain these two elements during the pouring of the filling material.
• the ring carrying the contactor is placed in the bore 6 of the counterweight 2.
• the springs 13 and 14 are positioned.
• the magnet is placed in its correct axial position and then fixed by crimping to the support constituted by the counterweight body.
• the printed circuit is soldered to the terminals of the contactor.
• the weight body is deformed so as to constitute the fold 17.
• the contactor 7 In the rest position shown in FIG. 2, the contactor 7 is in its axial position furthest from the magnet 11. The contactor is kept away from the magnet by the spring 13.
• the flyweight 2 having a certain inertia (or remaining integral with the ground following friction on this last), a traction of the trap wire 3 causes a translation of the mobile element (constituted by the ring 5 carrying the contactor 7 and the printed circuit 9) relative to the support constituted by the counterweight body 2 carrying the magnet 11.
• the axial displacement of the contactor with respect to the magnet here causes the contact to close (it is also possible to use normally closed contactors and for which the axial displacement will cause the contact to open).
• the magnet thus constitutes a means of detecting the displacement of the latter.
• the relative axial position of the magnet and the contactor will be chosen according to the sensitivity characteristics desired for the device. If the magnet is placed relatively close to the contactor, a short stroke of the latter will cause its change of state.
• the change of state of the contactor is used by the processing electronics 4 to cause the initiation of the mine.
• the invention allows a precise analysis of the stresses received by a trap wire, which makes it possible to no longer be dependent on the tension given to the wire during the setting up of the mine.
• the device according to the invention is therefore particularly well suited to dispersible mines.
• the damping means makes it possible to avoid vibrations of the mobile element, which adds to the precision of the signal formed by the succession of contact openings and closings.
• Those skilled in the art may adjust 'the device of the sensitivity according to the invention by acting on different parameters: the stiffness or springs, damping provided by the shape memory spring, stroke of the contactor, axial position of the magnet.
• FIG. 3 describes a second embodiment of a detection device according to the invention.
• the contactor 7 is made integral with a socket 20 by a filling 10 with resin.
• the sleeve 20 is arranged in a bore 21 arranged in a support 22 secured to the body of the mine itself.
• the sleeve 20 abuts against a counterbore 23 and it is immobilized axially by the printed circuit 9, itself fixed to the support 22 by flanges 24.
• the terminals 8a and 8b of the contactor 7 are connected to the processing electronics 4 via the connection printed circuit 9.
• the magnet 11 is made integral with a tube 25 (for example by gluing).
• This tube 25 is slidably mounted in a bore 26 arranged on the support 22. Such an arrangement makes it possible to adopt for the tube 25 a material promoting sliding.
• the trap wire 3 is fixed to the magnet by any suitable means (by screws, welding or crimping).
• the magnet integral with the tube 25 thus constitutes a movable element capable of translating relative to the support 22 during movement of the trap wire 3.
• the contactor 7 then constitutes the means making it possible to detect the movement of the magnet.
• the contactor shown here is kept in the closed state by the magnet. A movement of the latter will cause the contactor to open.
• a compression spring 13 is disposed between the magnet 11 and a cover 27, itself fixed by screws on the support 22.
• the spring 13 keeps the magnet 11 in abutment on the resin filling 10.
• Damping means for example a spring of shape memory material could be arranged between the magnet and the cover.
• a rubber seal 16 seals at the level of the passage of the trap wire 3. It is arranged in a groove 28 arranged on the cover 27.
• the advantage of this embodiment is that it allows the use of a non-conductive trap wire (therefore cheaper). We could for example use a nylon thread.
• the flyweight 2 which is ejected from the mine can then be full.
• the operation is similar to that of the device according to the embodiment of Figure 2.
• the movable element is here constituted by the magnet, the contactor remaining fixed.
• a displacement of the trap wire will cause a translation of the magnet and a change of state of the contactor.
• this embodiment makes it possible to design a very sensitive detection device.
• the processing electronics 4 can also process the information constituted by a succession of openings and closings of the contactor.
• FIG. 4 describes a third embodiment of a detection device according to the invention.
• This embodiment comprises a counterweight 2 having a bore 6 inside which is disposed a cylinder 29 made integral with the counterweight 2 by an annular crimping 30.
• a plate 31 of rectangular shape and of reduced thickness (of the order of a millimeter) is fixed by gluing to the cylinder 29.
• the plate can be made of a material having a relatively high coefficient of elongation under tension (for example Polyamide plastic).
• the plate 31 constitutes a fixed element on which the trap wire 3 is fixed.
• the plate carries, glued on a rectangular face, a strain gauge 32.
• the trap wire 3 consists of two conductors connected to the processing electronics 4.
• the conductors are connected to the terminals 32a and 32b of the strain gauge 32.
• the trap wire is also connected by a point of glue 33 to the plate 31.
• a spacer 15 is supported on the cylinder 29, it provides a holding surface for a rubber cover 16 which seals at the level of the passage of the trap wire 3.
• a fold 17 of the body of the counterweight 2 maintains the sealing cap 16 on the spacer 15 by pinching.
• the device operates as follows:
• a traction of the trap wire 3 will cause a deformation of the plate 31, this deformation causes a modification of the resistance of the strain gauge 32.
• This modification is analyzed by the processing electronics 4.
• the advantage of this embodiment is that it is possible to analyze precisely and continuously the deformation signal of the wafer, therefore not to initiate the mine only under well-defined conditions of movement of the trap wires, or even with a particular combination of the signals supplied by different trap wires.
• Those skilled in the art can adjust the sensitivity of the device by an appropriate choice of the characteristics of deformation of the wafer (material, shape) and of the sensitivity of the gauge.
• the strain gauge will then be fixed at the base of the U.
• a pull on the trap wire will have the effect of opening the U, the separation of the two branches of the U causing a deformation of the base of the U.
• Such a wafer shape makes it possible to obtain deformations that are easy to detect and measure by the gauge, even when it is stressed with minimal effort.
• FIG. 5 describes a fourth embodiment of a detection device according to the invention.
• the plate 31 is glued to a plug 34.
• the latter is fixed by thread in a bore 26 of the support 22 which is integral with the body of the mine itself.
• the terminals 32a and 32b of the strain gauge 32 are connected to the processing electronics 4 by conductors 35a and 35b which pass through the plug 34 ' at the level of a hole 36.
• the trap wire 3 is fixed to one end of the plate 32 by a point of glue 33.
• This embodiment makes it possible to use a non-conductive trap wire therefore inexpensive.
• This embodiment also makes it possible to obtain a high sensitivity due to the inertia of the mine to which the wafer is fixed.
• Other variants are possible without departing from the scope of the invention. It is possible, for example, to have electronic components on the printed circuit 9 (FIG. 2) ensuring a first processing of the information supplied by the contactor (electronic filtering, shaping of the signal slots).
• strain gauge plate integrated with the mine as in FIG. 5
• counterweight comprising a contactor
• FIG. 6 represents in axial section a detection device according to a fifth embodiment of the invention.
• the trap wire 3 is constituted here by a pair of conductors 3a, 3b connected to the processing electronics 4.
• the counterweight 2 also forms a substantially cylindrical housing inside which the trap wire 3 penetrates.
• the ends of the conductors 3a and 3b are soldered to an electrical circuit 37 applied to a plate 38 according to the conventional technique of printed circuits.
• the circular plate 38 is made of insulating material.
• the electrical circuit 37 comprises two conductive pads, carried by a first face 38a of the plate, and on which the ends of the conductors 3a, 3b are welded.
• conductive pads are connected by conductive bridges 40a, 40b to two conductive tracks 39a, 39b carried by a second face 38b of the plate 38 (see also Figure 6a).
• the plate 38 carries a circular axial opening 41 which is intended to allow the passage of the trap wire 3.
• a membrane 42 is applied to the face 38b of the plate 38.
• This membrane is made of a flexible synthetic material, for example silicone-fluorine.
• It comprises a central part 42a on which a hole 46 is arranged through which the trap wire 3 passes.
• the membrane 42 and the plate 38 are mounted in the counterweight by means of spacers 43 and 44.
• the spacer 43 allows the plate 38 to be positioned relative to the bottom of the counterweight 2.
• the membrane 42 is in contact with the plate 38, and its peripheral part 42b is immobilized relative to the support constituted by the counterweight 2 by means of the second spacer 44.
• a fold 17 of the body of the counterweight 2 ensures the axial immobilization with respect to the counterweight of the spacers 43 and 44, of the plate 38 and of the peripheral part 42b of the membrane.
• the fold 17 also maintains a pinch seal 16 on the spacer 44 by pinching.
• the spacers also make it possible to compress the peripheral part 42b of the membrane, which presses the latter against the internal surface of the counterweight and improves the seal. As a variant, it would be possible not to provide a cover 16, the seal then being ensured by the membrane 42 alone.
• the central 42a and peripheral 42b parts of the membrane are separated by a thinned area 42c which allows the deformation of the membrane.
• the thinned zone here results from an annular groove 45 produced on one face of the membrane 42.
• the width and depth of the groove are chosen by a person skilled in the art so as to give the membrane 42 the desired flexibility for the type of material considered.
• the hole 46 through which the trap wire passes is closed by filling with a material, such as glue, which ensures both sealing and mechanical joining of the trap wire 3 and of the central part 42b of the membrane
• the membrane 42 has a conductive surface which is in contact with the tracks 39a and 39b of the electrical circuit 37 and which electrically connects these two tracks.
• the membrane 42 thus closes the circuit 37 by ensuring an electrical connection between the conductors 3a and 3b.
• the material of the membrane will preferably be a conductive material, for example a synthetic material comprising a metallic or carbon filler.
• the assembly of the device is carried out as follows:
• the trap wire 3 is passed through the hole 46 of the membrane, then the trap wire is glued to the latter,
• the weight body is deformed so as to constitute the fold 17.
• the elasticity of the membrane material causes the central part of the latter to come back into contact with the tracks 39a, 39b when the trap wire is released.
• the change of state of the contactor is used by the processing electronics 4 to cause the initiation of the mine.
• the thinned zone 42c a shape (by molding) such that the central part of the membrane does not return after separation of the tracks 39a, 39b.
• FIG. 7 shows in axial section another embodiment of the invention in which the membrane 42 and the plate 38 are arranged in a bore 26 arranged in a support 22 secured to the body of the mine itself.
• the bore is closed on one side by the cover 27 and on the other by the threaded plug 34.
• Spacers 47, 48 ensure the axial positioning of the membrane and the plate in the bore 26. They also ensure the integral with the support 22 of the plate 38 and the peripheral part 42b of the membrane.
• a rubber seal 16 seals at the level of the passage of the trap wire 3. It is arranged in a groove 28 arranged on the cover 27.
• the trap wire 3 is fixed to the central part of the membrane 42 at the level of a hole 46 filled with glue.
• the advantage of this embodiment is that it makes it possible to use a non-conductive trap wire therefore inexpensive.
• the flyweight 2 which is ejected from the mine can then be full.
• the inertia of the mine being greater than that of the counterweight, this embodiment makes it possible to design a very sensitive detection device.
• the operation is similar to that of the device according to the embodiment of FIG. 6.

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• 1993
  • 1993-07-22 FR FR9309002A patent/FR2708099B1/fr not_active Expired - Fee Related
• 1994
  • 1994-07-13 US US08/367,156 patent/US5600086A/en not_active Expired - Fee Related
  • 1994-07-13 WO PCT/FR1994/000883 patent/WO1995003522A1/fr not_active Application Discontinuation
  • 1994-07-13 EP EP94922921A patent/EP0662210A1/de not_active Withdrawn
  • 1994-07-21 IL IL11039894A patent/IL110398A0/xx unknown

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