Arrangement for remote sweeping of mines sensitive to magnetic fields

An arrangement for sweeping mines having firing systems which are sensitive to magnetic fields is disclosed which utilizes a remote control mobile floating body with a built-in propulsion system. A magnetic field is generated within a group of permanent magnets located within the floating body in such a manner that these permanent magnets are either individually controlled or controlled as a group so that various types of magnetic field mines can be detected.

BACKGROUND OF THE INVENTION 
FIELD OF THE INVENTION 
The present invention relates to a device which provides mine sweeping 
operations for detecting mines having ignition system sensitive to the 
magnetic fields. 
Sweep devices, in the form of towed live electrodes or cable loops of the 
double-wire circuit are used for remote sweeping of mines located beneath 
the surface of the sea. 
The power supply for the sweep devices is by means of generators on board 
manned sweeper crafts connected to towed cables. 
These crafts, which normally operate in formation, are used for sweeping 
magnetic and/or acoustic mines as described in German Patent Application 
DE-PS No. 20 14 623. The field winding of the generator is controlled by 
an electric signal transmitter for presetting a sweep program in the form 
of different types of signals via a servo component. 
In one variation, rods are housed in mobile, directionable floats in which 
the sweep current generators are also located. 
In this connection reference is made to the German Patent Application DE-PS 
No. 978 056 according to which the sweeper is in the form of a cylindrical 
pressure hull capable of floating which is encircled by windings having 
current passing therethrough. The pressure hull accommodates the power 
propulsion generator, the magnetic field and the sound waves. 
One or more of these floats are remotely controlled by a manned 
mother-ship. 
Each of these prior art devices produce the magnetic sweep field 
electromagnetically and in the case of high sweep performances there is a 
considerable consumption of power which greatly reduces the utilization 
time and consequently prevents a fast sweep of large areas. Furthermore, 
it is common to these devices that the far zone and, to a certain extent, 
the near zone can be considered as homogeneous at short distances. Thus 
these devices cannot be used to sweep mines with magnetic differential 
field or gradient ignition systems or else they would be destroyed if the 
mine in the near zone receives sufficiently high gradients as in the 
arrangement utilizing magnetizable rods. 
SUMMARY OF THE INVENTION 
According, it is an objective of the invention to create a device for 
remote sweeping of mines sensitive to magnetic fields, which is also 
suitable for remote sweeping of differential fields or gradient mines and 
which allows long periods of operation with minimum consumption of power. 
In this type of sweeper, large sources of power are not needed, and thus 
the particular advantage of the solution according to the invention is 
that it entails low costs to produce the device and in particular all 
prior knowledge of manufacture and operation of torpedos can be utilized.

The float (3) according to FIG. 1, which is similar in shape to a torpedo, 
has, in addition to the usual sonar and control section (4) and drive 
section 6, a sweep section 5 in which a series of disc-shaped permanent 
magnets 8 are found. As can be seen from FIG. 2, these are positioned to 
rotate around an axis 10 in a cylindrical hull 7 and can be turned in any 
angle position by a remote controlled motor with gear 9. FIG. 2b shows the 
magnetic disc 8 in the direction of magnetization. 
For the setting up of a sweep field produced by a magnetic dipole, all 
magnetic discs 8 are tuned in such a way that the direction of the planar 
normal line conforms with the axis of the float and the direction of 
magnetization is equal. The sweep field produced in this way H.sub.PD is 
approximately 
##EQU1## 
M is the magnetization of the magnetic disc, m the magnetic moment, r the 
distance to the top point, a the diameter and d the thickness of the disc. 
In order to obtain a stronger field gradient at greater distances, as for 
instance is necessary for sweeping of gradient mines, a double dipole 
field is produced by reversing the direction of half of the magnetic discs 
(see FIG. 1). The resulting magnetic field H.sub.P r is as follows 
##EQU2## 
In the most general case, any arbitrary desired angle position of the 
magnetic disc can be set so that the magnetic field is not too close for 
estimation by the following formula: 
##EQU3## 
In order not to endanger the carrier in the transport of float 3, the 
magnetic discs 8 are turned with their planar normal lines perpendicular 
to the float axis whereby the magnetization direction alternately turns 
itself by 180.degree.. A resulting field is then obtained which dampens 
very quickly with 
##EQU4## 
so that the field current remains negligably small even at short 
distances. 
If particular sweep tasks require a time change in their course, then the 
magnetic disc angle can be altered in relation to the longitudinal axis of 
the float 3 by means of a suitable timed remote or programmed control. 
Furthermore a sweep program can be input to the float 3 which runs 
automatically. At the end of the program, the float returns independently 
to a carrier craft. 
Only materials with sufficiently high coercive field force can be used as 
magnetic material in order to prevent demagnetization when the magnetic 
discs are turned. Among the materials presently known, rare earth magnetic 
materials are particularly suitable. With regard to ferrites, the sweep 
distance is smaller due to the small magnetic saturation. 
All systems known from torpedo technology can be used to drive the float 3 
such as electric and diesel motors. 
In particular, the float can be quipped with a three phase motor which is 
supplied via a three-phase cable from the carrier craft and float. This 
cable can contain also a wire or optical waveguide to transfer remote 
control signals. 
In addition, for sweeping of acoustic sensitive mines, the float can 
contain or tow a sound producer, which gives off a frequency spectrum 
specific to the ship. 
Furthermore, in the sonar and control unit 4, measuring devices for 
magnetic fields can be provided. 
Obviously, numerous modifications and variations of the present invention 
are possible in light of the above teachings. It is therefore to be 
understood that within the scope of the appended claims, the invention may 
be practiced otherwise than as specifically described herein.