EP0125180B1 - Remote mine-sweeping apparatus for mines with magnetic firing means - Google Patents

Description

The present invention relates to a remote demining device for mines sensitive to magnetic fields.

It is known that in remote mine clearance of mines which are below the sea surface, electrode or solenoid devices are used.

The energy supply for these demining devices is done by electric generators which are on board minesweepers and by floating cables which are pulled by the dredgers.

These boats, which normally go into formation, are used to dredge mines with magnetic firing or mines with magnetic and acoustic firing or only acoustic mines as described in German patent DE-C-2014623.

The excitation coils of electric generators for minesweeping are powered by an electric function generator to produce a demining program.

In another form, iron bars are located in small motor-driven floats on which there are also generators that produce the current necessary for mine clearance. These systems are described in German patent DE-C-978056. In this patent the float is constructed of iron like a pressure shell which carries the electric coils. The float carries the generators for propulsion, the magnetic field and the acoustic field. One or more floats are guided by a tanker.

It is known for all these systems to produce the magnetic field for demining considered by electric generators. The energy supply is very large to have very strong magnetic fields, which reduces the mission time and prevents rapid clearance of large areas of the sea.

In addition, it is known for all these systems that the long-range magnetic field, and to some extent the proximity magnetic field, can be considered to be homogeneous. This is why these systems cannot be used for mine clearance with fires sensitive to the magnetic field gradient, and the mine clearance systems themselves can be destroyed when the mine measures a fairly strong magnetic field gradient. in the vicinity of the system, as it exists with solenoid systems.

It is also known from patent US-A-4,220,108 to use a mobile body towed by a helicopter and in which a bar-shaped magnet can be rotated as a function of the towing speed thereby creating a periodically variable magnetic field . Such a device according to the preamble of claim 1 cannot simulate the field of an important building and in particular the gradient at long distance similar to that of large buildings for which the firing of mines is generally regulated.

In order to be able to simulate such a field, the invention provides a remote mine clearance device comprising a firing system sensitive to the magnetic field, a device being located in a remote-controlled mobile body navigating in the sea and comprising at least one magnet. the position of which inside the movable body can be modified during the demining operation, mainly characterized in that it comprises a set of disc-shaped magnets, one face of which is a north pole and the other face a south pole, these disks being distributed along the longitudinal axis, of the movable body and fixed on a vertical axis of rotation passing through a diameter of the disk, and the orientation of the disk around this axis of rotation can be modified separately for each disc by remote control or using a programmer contained in the mobile body to modify the distribution of the field produced by all the discs.

This movable body can be additionally equipped with a guide section, a sonar, and a propulsion section.

As this system does not have large generators to produce the magnetic demining field, the main advantage of the invention is that the manufacture of such a system is not expensive and that knowledge on the manufacture and launching of torpedoes can be used.

• - le corps mobile contient une installation pour mesurer le champ magnétique,
• - le corps mobile exécute tout seul un programme de déminage qui lui a été fixé avant la mission et retourne à la fin du programme automatiquement au bateau de lancement,
• - le corps mobile contient en plus un système acoustique de déminage.

Complements of the invention are characterized as follows:

• - the moving body contains an installation for measuring the magnetic field,
• - the mobile body alone executes a demining program which was fixed to it before the mission and returns automatically at the end of the program to the launching boat,
• - the moving body also contains an acoustic demining system.

• - la figure 1 représente un dispositif de déminage en forme de torpille;
• - la figure 2 représente plusieurs vues d'un aimant permanent qui sert à produire le champ magnétique.

Other characteristics and advantages of the invention will be better understood on reading the following description of an exemplary embodiment and with reference to the drawings in which:

• - Figure 1 shows a demining device in the form of a torpedo;
• - Figure 2 shows several views of a permanent magnet which is used to produce the magnetic field.

According to Figure 1 the mobile torpedo-shaped body has in addition to a guide section and a sonar (4) a demining section (5) in which there is a set of permanent magnets (8) in disc shape.

According to Figure 2 the permanent magnets can be rotated around an axis of rotation (10) which is in a cylindrical shell (7) using an unmanned motor and a mechanism (9) according to the angle longed for.

Figure 2b shows the permanent magnet disk in the direction of magnetization.

avec

pour

M représentant la magnétisation de chaque disque, m représentant le moment magnétique du dipole, r la distance, a le diamètre et d l'épaisseur des disques.To adjust the magnetic mine clearance field produced by a magnetic dipole, the discs are adjusted so that the direction of the normal to the disc conforms to the axis of the moving body. The magnetic field resulting from H _PD clearance will be:

with

for

M representing the magnetization of each disc, m representing the magnetic moment of the dipole, r the distance, has the diameter and d the thickness of the discs.

To obtain a stronger magnetic field gradient at greater distances from the moving body, which may be necessary for clearance of mines sensitive to the gradient of this magnetic field, the magnetic field of a double dipole is produced by turning one half discs in reverse (see Fig. 1

The resulting magnetic field will be:

It is possible to adjust the discs according to each angle between the normal and the axis of the moving body and we can estimate the magnetic field at long distance at:

In order not to endanger the launching boat during the transport of the moving body, the discs (8) are adjusted so that the normal is perpendicular to the axis of the float. In addition, the directions of magnetization of each disc are alternated 180 ° relative to each other.

(n = nombre de disques) pour que la perturbation soit minimale à courte distance.In this case, a magnetic field is obtained which is canceled out quickly with the neighbor according to:

(n = number of discs) so that the disturbance is minimal at short distance.

If special clearance missions require a change in the magnetic field for a period of time, the direction of normal of the disks with the axis of the moving body can be changed by remote control or by program as required.

In addition, the moving body can contain a demining program, which is executed. At the end of the program, the moving body automatically returns to the launching boat.

As the material for the discs it is currently only possible to use materials having a high coercive force to prevent demagnetization of the discs when they are rotated. As known material, rare earths or combinations comprising rare earths can be used. If ferrite-based materials are used, the clearance distance will be shorter.

For the propulsion of the mobile body, the known propulsion systems for torpedoes can be used, such as electric motors, diesel engines or others.

In particular, the mobile body can be equipped with a three-phase motor which is supplied by the boat by a cable. This cable can at the same time have locations for the remote control by an electric wire or an optronic line.

For the clearance of acoustic mines the mobile body can be equipped with an acoustic generator which produces an acoustic field simulating the acoustic field of the target, or even it can tow such a generator.

The guidance and sonar section may also contain facilities for measuring the magnetic field.

Claims (5)

1. Device for the remote elimination of mines, comprising a magnetic field sensitive firing system, this device being located in a remote controlled movable body (3) navigating in the sea and comprising at least one magnet the position inside the movable body of which can be modified during the mine elimination procedure, characterized in that it comprises a set of disc-shaped magnets (8) one face of which is a north pole and the other of which is a south pole, these discs being distributed along the longitudinal axis of the movable body (3) and affixed on a vertical rotary axis (10) extending through a diameter of the disc, and the orientation of the disc about this rotary axis being susceptible to be modified separately for each disc by remote control or by means of a programmer (4) contained in the movable body to modify the distribution of the field produced by the set of discs.

2. Device according to claim 1, characterized in that the movable body (3) contains a magnetic field measuring system (3).

3. Device according to any of claims 1 and 2, characterized in that the programmer (4) controls the execution of a mine elimination program which has been given thereto prior to the mission and the automatic return of the movable body to the launching ship at the end of the program.

4. Device according to any of claims 1 to 3, characterized in that the movable body (3) further contains an acoustic mine elimination system.

5. Device according to any of claims 1 to 4, characterized in that the direction of the permanent magnets (8) other than during the mine elimination mission is such that the intensity of the outer magnetic field is reduced to minimum.

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