GB2227819A - Explosive mine - Google Patents

Abstract

A mine comprises a remotely operable detonator charge movable repeatedly between armed and safe positions, and includes an indicator 5 providing in the safe state a status indication visible from a safe distance and having a part 21 which can be driven into and out of a housing 23. A single power source is switched to either the indicator device or the detonation system, the switch being controlled so that only in the safe state can the indicator be operated. The indicator 5 incorporates either a reflector, a radio-frequency receiver or an active light 31. The reflector may be seen from a vehicle in the light of the vehicle headlamps or by means of an IR transmitter and sensor mounted on the vehicle. The vehicle may then illuminate a path through the minefield. <IMAGE>

Description

EXPLOSIVE MINE This invention relates to explosive mines particularly of the kind known as 'land service mines'. A feature of certain mines of this type is that a detonation charge is moved between a safe position and an active or 'armed' position on arming the mine, so that the mine can be stored and transported in the safe condition, and armed immediately before or after installation in the target area. Operation of the charge carrier from the safe to the armed position can be performed remotely, by an electric signal operating a solenoid for example. The firing arrangement for the detonator charge is arranged so that it can only be operated effectively when the charge carrier is in the armed position. The firing operation may itself require a composite enabling signal.

Once the mines are laid, it may be necessary or desirable for them to be disarmed to allow passage of friendly troops or vehicles for example. This requires movement of the charge carrier either back to its original safe position or on to a further safe position. While this disarming operation may be performed manually it may be effected automatically, for example at the end of a pre-set time delay and/or when the battery capacity falls below a pre-set level. Modern mines can also incorporate means for remote disarming - for example in response to a signal transmitted by land-line, fibre optic cable, radio, infra-red beam or otherwise.

Such disarming is commonly a 'single-shot' operation in that, for example, an explosive 'marking charge' is employed to attain the disarmed state and activate a flag or other indicator.

The present invention is concerned with explosive mines which can be repeatedly armed and disarmed remotely.

In all cases personnel in vehicles which have to pass through the minefield, or who have to approach the mines, on foot, to lift them, need to have assurance that the mine has been positively disarmed, and is in a safe condition, ie they require 'status assurance'.

Methods have been used where either some form of simple visual/tactile indicator 'pops out' of the mine, or a short range hand-held interrogator unit is used to elicit a response from the mine - for example, by inductive means. Such methods are limited in range, and hence are of no use in cases such as: Opening of a wide gap ( 200m) in a minefield, to allow counter-attack by our own armoured forces.

Disarming/lifting an anti-personnel mine, equipped with, either long trip-wires, or a proximity sensor, to prevent close examination.

Accordingly, an object of the invention is to provide a mine with a status indicator which is visible from a considerable distance.

According to the present invention a mine comprises remotely operable detonation means including a detonation charge movable repeatedly between armed and safe positions, and further comprises indicator means for providing a visual indication, over and above that arising from ambient illumination, of the armed/disarmed state of the mine, this visual indication being visible from a safe distance.

The indicator means may be apparent in the disarmed, safe, state and not apparent in the armed state.

The indicator means and the detonation means preferably employ a single power source and switching means adapted to supply each of the indicator means and the detonation means selectively, the switching means being operable in dependence upon the armed/safe position of the detonation charge.

The indicator means may be an active light source.

Alternatively, the indicator means may comprise reflector means adapted to return an indication signal when illuminated.

The indicator means may comprise a radio-frequency receiver and be operable in response to a predetermined signal received by the receiver.

The indicator means may comprise signal decoding means, the indicator being provided only on reception of a predetermined interrogation signal.

A minefield control system may comprise a plurality of mines as aforesaid, remote means for disarming the mines and activating the indicator means of selected mines.

In such a system, the remote means for disarming the mines may be arranged to activate the indicator means of disarmed mines, only when the mines have been safely disarmed.

One embodiment of explosive mine and minefield control system will now be described, by way of example, with reference to the accompanying drawings, of which: Figure 1 is a diagrammatic view of a mine buried just below ground; Figure 2 is a diagram of the mine status indicator; Figures 3 (a) (b) and (c) are diagrams of a disarmed mine being detected by a friendly vehicle (tank); Figure 4 is a diagrammatic plan view of a safe track through a mineield.

The mine comprises a main charge and a fuze comprising a chain of several stages of explosive. The first of this chain is a small charge mounted in a movable carrier. In this embodiment the charge carrier -starts in one safe position with the charge out of alignment with a charge train, is driven by solenoid into an active position in which the charge is aligned with the charge train and latched in this position. In the safe condition the firing signal has no complete path to the detonator and even if a fault completed the circuit the charge is out of the firing position and unable to detonate the main charge. The mine, in the armed condition, awaits a firing signal for the detonator, produced by a proximity fuze in known manner with the approach of a target.

Referring to Figure 1, a mine 1 is shown buried just below ground level. The mine comprises a main charge 2 and a fuze device 3 including a remotely operable arming mechanism and a proximity detector which supplies a firing signal to the fuze. When the mine is armed this firing signal is effective to fire a detonator and thus explode the main charge 2.

The arming mechanism is operated by a solenoid, powered by a battery and triggered by a signal received on a fibre-optic line 4.

A further signal from the remote control centre will then-disarm the mine and reset it to the safe, ie disarmed, condition. This may be done repeatedly.

Mounted on the fuze body 3 is a mine status indicator 5 which is shown in more detail in Figure 2. The indicator includes a moveable upper part 21 and a lower housing 23 formed in the fuze body. The upper part 21 has a rack 25 attached to it by which it is driven in and out of the housing 23. The rack in turn is driven by a pinion 27 and electric motor/gearbox combination 29 mounted in the housing.

The part 21 houses a light source 31, which may be a tritium-powered, beta light, mounted at the focus of a downwardly facing concave mirror 33. Light from the source 31 is thus reflected vertically downwards onto a conical mirror 35 surrounding the source 31. From here it is reflected horizontally outwards, through a lens 37. A typical light path 39 is illustrated.

The status indicator is circular in plan view and emits light at all azimuth angles. It may be desirable to limitemission of the signal to a particular sector in which it is known that 'friendly' personnel will be approaching. For this purpose a shutter 41 surrounds the light housing and can be rotated and raised/lowered to block light in other directions.

A retraction of the indicator a cover 43 is sealed to the fuze body 3 by way of O-ring seal 45.

In an alternative arrangement, the lens 37 is replaced by a reflecting surface, eg a multiple quadrant, reflex reflector to return an incident beam along its own path.

The indicator device is powered hy the same battery as the fuze/detonator system. The electrical supply is switched to one or the other exclusively. The switch is controlled by the physical operation of the detonator shutter so that power cannot be supplied to the indicator, wither to raise the indicator or energise the light, in the armed condition. Operation to the safe condition closes the indicator circuit and permits its operation.

A further precaution is a mechanical interlock between the detonator shutter and the indicator to prevent the latter being raised in the armed condition.

Remotely controlled mines operate on an external instruction signal to disarm following which a 'handshake' signal is transmitted by way of the fibre-optic lint.

An additional interlock can be provided to ensure that the 'handshake' signal returned by the mine to the control system, can not be transmitted until the disarming/neutralisation functions have been correctly carried out, and the assurance indicator has popped-up.

The means of disarming/neutralising, and of erecting the assurance indicator, are designed to be 'reversible', so that the mine can be returned to the 'armed' state, if so required - either manually, or in response to an internal timed command, or by remote command.

The indicator itself may, as described above, consist of a reflector or an active light source. In the case of a reflector it may operate on visible light with say, a green filter incorporated to distinguish the reflection from any other reflecting object. The green reflector will be visible when illuminated by, say, the headlamps of the detecting vehicle. This is shown in Figure 3(a).

In Figure 3(b) the vehicle (tank) carries an infra-red beam source and an I.R. sensor.

In Figure 3(c) the indicator is 'active' as described above with reference to Figure 2, and may be a beta-light source. An optical detector is then positioned on the vehicle.

The reflector/source may be arranged to be effective over 360" in azimuth, or to operate over a more limited arc, for example, by the use of the above described screening means: similarly, the beamwidth may be restricted in elevation. This facility will minimise the probability of the enemy making use of the assurance indicator to assist him to cross/clear the minefield.

Increased security can also be provided by making the indicator respond only to a specific, coded, illuminating means, e.g.

by incorporating a simple detector and signal processor to decode the flashes - inhibiting the indicator if the correct code is not received (by the mine).

Figure 4 shows a plan view of a tank negotiating a safe path through a minefield. Mines in a wide path through the minefield have been disarmed, these being referenced 11. Two of these mines, 13, are in an indeterminate state. Those referenced 111 within the illuminating beam 15 of an oncoming tank 17 reflect the beam, the reflection being detected by a sensor on the tank. A path 19 is then chosen through the minefield to pass over those disarmed mines 111 giving a proper 'disarmed' indication.

Claims (10)

1. A mine comprising remotely operable detonation means including a detonation charge movable repeatedly between armed and safe positions, the mine further comprising indicator means for providing a visual indication, over and above that arising from ambient illumination, of the armed/disarmed state of the mine, said indication being visible from a safe distance.

2. A mine according to Claim 1, wherein said indicator means is apparent in the disarmed, safe, state and not apparent in the armed state.

3. A mine according to Claim 1 or Claim 2, wherein said indicator means and said detonation means employ a single power source and switching means adapted to supply each of said indicator means and said detonation means selectively, said switching means being operable in dependence upon the armed/safe position of said detonation charge.

4. A mine according to any preceding claim, wherein said indicator means is an active light source.

5. A mine according to any of Claims 1, 2 and 3, wherein said indicator means comprises reflector means adapted to return an indication signal when illuminated.

6. A mine according to any of Claims 1, 2 and 3, wherein said indicator means comprises a radio-frequency receiver and is operable in response to a predetermined signal received by said receiver.

7. A mine according to Claim 5 or Claim 6, wherein said indicator means comprises signal decoding means, said indicator being provided only on reception of a predetermined interrogation signal.

8. A minefield control system comprising a plurality of mines according to any preceding claim, remote means for disarming the mines and remote means for activating the indicator means of selected mines.

9. A control system according to Claim 8, wherein said remote means for activating the indicator means is arranged to activate the indicator means of disarmed mines.

10. A mine substantially as hereinbefore described.