EP0623506B1 - Verfahren zur automatischen Kompensation des Remanenz-Magnetismus einer ferromagnetischen Minenräumanlage - Google Patents

Verfahren zur automatischen Kompensation des Remanenz-Magnetismus einer ferromagnetischen Minenräumanlage Download PDF

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Publication number
EP0623506B1
EP0623506B1 EP19940400955 EP94400955A EP0623506B1 EP 0623506 B1 EP0623506 B1 EP 0623506B1 EP 19940400955 EP19940400955 EP 19940400955 EP 94400955 A EP94400955 A EP 94400955A EP 0623506 B1 EP0623506 B1 EP 0623506B1
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European Patent Office
Prior art keywords
gradient
cores
value
magnetization
central core
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EP19940400955
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English (en)
French (fr)
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EP0623506A1 (de
Inventor
Jean-Jacques Periou
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Thales SA
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Thomson CSF SA
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63G—OFFENSIVE OR DEFENSIVE ARRANGEMENTS ON VESSELS; MINE-LAYING; MINE-SWEEPING; SUBMARINES; AIRCRAFT CARRIERS
    • B63G9/00—Other offensive or defensive arrangements on vessels against submarines, torpedoes, or mines
    • B63G9/06—Other offensive or defensive arrangements on vessels against submarines, torpedoes, or mines for degaussing vessels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63G—OFFENSIVE OR DEFENSIVE ARRANGEMENTS ON VESSELS; MINE-LAYING; MINE-SWEEPING; SUBMARINES; AIRCRAFT CARRIERS
    • B63G7/00—Mine-sweeping; Vessels characterised thereby
    • B63G7/02—Mine-sweeping means, Means for destroying mines
    • B63G7/06—Mine-sweeping means, Means for destroying mines of electromagnetic type

Definitions

  • the present invention relates to methods which make it possible to automatically compensate for the residual magnetization which persists in a ferromagnetic type dredge when it has been put out of service. This makes it possible to remove from it, when necessary, all efficiency and therefore any danger in order to be able to handle and / or store it without risk.
  • Dredges adapted to the operating principle of these devices are used to dredge mines.
  • mechanical devices intended to cut the ruts are towed behind the dredger, and in the case of acoustic mines of submerged vehicles comprising sound sources intended to actuate the firing device. sufficient distance from the dredger.
  • These firing devices have of course been improved so as not to be deceived by the relatively coarse simulation devices used at the start.
  • the device described in this patent application comprises a series of ferromagnetic elements towed in single file behind a minesweeper. Each of these elements is itself composed of 19 cores surrounded by coils. These windings are associated with current pulse generators adjustable in direction and in amplitude. These pulses make it possible to generate within each ferromagnetic core separately, a magnetic field which makes it possible to magnetize at saturation the core in one direction or the other and to demagnetize it, at least to a certain extent, enabled by the hysteresis cycle of the material used to build the nucleus.
  • each of the cores makes it possible to obtain for each element a magnetic field which is adjustable in steps in intensity and in direction.
  • the magnetization provided by each of the elements can be adjusted in this way, the magnetic signature of a boat can be simulated in a relatively fine manner.
  • 18 of its nuclei can be brought to magnetic saturation by grouping them in such a way that two consecutive nuclei have opposite magnetization directions and by demagnetizing the 19th nucleus located in the center.
  • 18 of its nuclei can be brought to magnetic saturation by grouping them in such a way that two consecutive nuclei have opposite magnetization directions and by demagnetizing the 19th nucleus located in the center.
  • a dredging element is capable of providing a maximum magnetization equal to 70,000 Am 2 , a residual magnetization of 5%, current value, or 3,500 A m 2 , generates a magnetic field of 300 nT at a distance 9 m, corresponding to the standard water height adopted for this type of device.
  • the dredge has 6 identical elements and the residual field generated by these 6 elements grouped together in one place on the dredger deck can then reach a value of 1,800 nT at this distance from 9 m.
  • French patent 2,559,303 discloses a method for compensating the magnetic fields of any object in which in particular differential magnetometers are used to measure the field to be compensated.
  • this compensation is essentially carried out by the action of a loop traversed by an electric current and whose field is opposed to that to be compensated.
  • the modification of the magnetization of the object which can possibly be caused by the loop is only partial and it is necessary to maintain a permanent current in this loop.
  • the invention provides a method according to the appended claims.
  • FIG. 1 a cross section of a ferromagnetic dredge element.
  • This element is formed by 19 cores 101 distributed over two concentric crowns, an outer crown comprising 12 cores plus an inner crown comprising 6 cores, plus a single central element forming the 19th nucleus.
  • Each core is itself formed by a set of bars 102, joined together in the form of an elongated packet enclosed by a coil 103 enabling them to be magnetized in the desired manner by causing this coil to pass through an adequate current.
  • the assembly is contained in an envelope 104 and the space between the cores inside this envelope is filled with a compound 105 making it possible to maintain the cores in the desired arrangement while participating in the hydrostatic balance of the element. .
  • the cores of the two crowns can be grouped in pairs, which allows one of them to saturate in one direction and the other to saturation in the other direction to cancel the total magnetization overall. of the two crowns of 18 cores.
  • the demagnetization of the central core is obtained by running the winding which surrounds it with a current which reduces this magnetization to 0.
  • Figure 2 a simplified longitudinal sectional view of the element of Figure 1 provided with additional members including in particular the means of the invention.
  • a magnetic field gradient meter 201 is used, located substantially on the axis of the central core at a distance d from the end of this core.
  • the distance d will be equal to 0.7 m.
  • This gradient meter 201 is a known device which measures the gradient of the field at a point in the space conventionally located at the center of the gradient meter and in a determined direction.
  • two probes 202 and 203 are used, of the so-called "flux-gate" type for example, aligned along the measurement axis.
  • the difference in the magnetic field measurements given by these probes makes it possible to obtain, as a function of their spacing, which is for example equal to 0.2 m, the value of the gradient at the central point between these two probes.
  • This device is in principle polarized along an axis which according to the invention will be the axis of the large magnet formed by all of the cores of the dredger element.
  • the gradient meter 201 is connected to an electronic unit 204 which supplies it with various service signals and analyzes the signals from the probes to determine the magnetic field gradient at the location where the gradient meter is positioned.
  • These electronic circuits also include means making it possible, from these measurement signals, to control a power supply device 205 for the windings 103 of the cores 101.
  • This device 204 operates in feedback so as to minimize, preferably to cancel, the magnetic field gradient measured by the magnetometer 201.
  • the demagnetization operation of the dredge element is launched by commanding a sequence d current pulses in the windings 103, by means not shown and known which come to control the power means 205 and which can themselves be contained in the members of the electronic unit 204, the magnetic field generated by the drag element outside of itself tends to cancel out, especially at the location where the gradient meter is located. The gradient of this field is then also canceled.
  • the residual magnetization is detected by the gradient meter which then controls via the box 204 the emission of complementary currents by the power box 205 in the windings, and in any case in at least one of them.
  • the gradient of the Earth's magnetic field if it is not always zero, is however often very low, except perhaps in the presence of certain anomalies due to ferromagnetic rocks.
  • the gradient coming from the dredger element is on the other hand much greater since one is at a distance d from this element relatively small compared to its dimensions. If therefore we manage to cancel this gradient, we are much safer to have canceled the residual magnetic field from the element.
  • a first method we start from the conventional method of global demagnetization of the element by saturation in opposite directions of the contiguous nuclei and demagnetization of the central nucleus without control at this level.
  • the servo system is then started up on the value 0 of the measurement of the gradientmeter and the latter comes to finely adjust the magnetization of the central core around the value in principle zero obtained previously.
  • this process is stopped when the value of the gradient is minimum, that is to say when there is no longer any variation in the gradient in at least two successive iterations of the process.
  • the value of the magnetization of the central core is then zero but in practice this will not be the case since there will be a small residual magnetization making it possible to compensate for the residual magnetization originating from the irregularities in the compensation two by two of the cores of the crowns.
  • the disadvantage of this first method is that obtaining a value 0 of the gradient at a point on the axis of the system does not guarantee a zero field in any space with sufficient precision. This could only be achieved if the drag element could be assimilated to a perfect magnetic dipole, which is not the case since the magnetizations of the cores arranged in a crown are not zero and are only compensated two by two. This compensation clearly does not give a homogeneous magnetic field and therefore zero at all points.
  • a second method then consists in first demagnetizing all the nuclei in the same way as the central nucleus was demagnetized in the first method.
  • the magnetization of each of the nuclei is varied slightly one after the other, cyclically from the first to the last, each time minimizing the field gradient determined by the gradient meter 201.
  • This second method gives superior results from the point of view of homogeneity in the space of the resulting zero field, but it has the disadvantage of being longer to implement since it is necessary to act on each of the nuclei one after the other.
  • each element of the dredge comprising three generally identical octagonal elements. It is then necessary to place a gradient meter per element and to implement the method for each of these elements separately.

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  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Measuring Magnetic Variables (AREA)

Claims (3)

  1. Verfahren zur automatischen Kompensation der Magnetisierung eines magnetisierten Elements mit Hilfe einer dieses Element umgebenden Wicklung, indem man durch diese Wicklung einen elektrischen Strom schickt, dessen Stärke aufgrund der Messung des Magnetfeldgradienten außerhalb und in der Nähe dieses Elements bestimmt wird, so daß der Wert des Gradienten möglichst klein wird, dadurch gekennzeichnet, daß das Element ein ferromagnetisches, geschlepptes Element ist, das von einem Schiff gezogen werden soll, daß das Element eine ungerade Anzahl von Kernen (101) mit einem zentralen Kern und mit mindestens einem eine gerade Anzahl von Kernen enthaltenden Ring um den zentralen Kern herum besitzt, daß die Messung (201) des Gradientenwerts in der Magnetachse des zentralen Kerns durchgeführt wird, daß die Kerne des Rings bis zur Sättigung magnetisiert werden, und zwar in benachbarten Kernen in entgegengesetzter Richtung, daß die Magnetisierung des zentralen Kerns im wesentlichen auf Null gebracht wird und daß die Magnetisierung des zentralen Kerns um den Wert Null herum geringfügig verändert wird, um den gemessenen Gradientenwert möglichst klein zu machen.
  2. Verfahren zur automatischen Kompensation der Magnetisierung eines magnetisierten Elements mit Hilfe einer dieses Element umgebenden Wicklung, indem man durch diese Wicklung einen elektrischen Strom schickt, dessen Stärke aufgrund der Messung des Magnetfeldgradienten außerhalb und in der Nähe dieses Elements bestimmt wird, so daß der Wert des Gradienten möglichst klein wird, dadurch gekennzeichnet, daß das Element ein ferromagnetisches, geschlepptes Element ist, das von einem Schiff gezogen werden soll, daß das Element eine ungerade Anzahl von Kernen (101) mit einem zentralen Kern und mit mindestens einem eine gerade Anzahl von Kernen enthaltenden Ring um den zentralen Kern herum besitzt, daß die Messung (201) des Gradientenwerts in der Magnetachse des zentralen Kerns durchgeführt wird, daß in einer ersten Phase alle Kerne entmagnetisiert werden und daß dann die Magnetisierung jedes Kerns nacheinander geringfügig um den Wert Null herum verändert wird, um den gemessenen Gradientenwert möglichst klein zu machen.
  3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, daß man den Prozeß solange wiederholt, bis der Wert des schließlich erhaltenen Gradienten von im wesentlichen Null sich von einer Wiederholung zur nächsten nicht mehr verändert.
EP19940400955 1993-05-07 1994-05-03 Verfahren zur automatischen Kompensation des Remanenz-Magnetismus einer ferromagnetischen Minenräumanlage Expired - Lifetime EP0623506B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9305516 1993-05-07
FR9305516A FR2704829B1 (fr) 1993-05-07 1993-05-07 Procede de compensation automatique de l'aimantation residuelle d'une drague ferromagnetique.

Publications (2)

Publication Number Publication Date
EP0623506A1 EP0623506A1 (de) 1994-11-09
EP0623506B1 true EP0623506B1 (de) 1997-08-06

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EP19940400955 Expired - Lifetime EP0623506B1 (de) 1993-05-07 1994-05-03 Verfahren zur automatischen Kompensation des Remanenz-Magnetismus einer ferromagnetischen Minenräumanlage

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FR (1) FR2704829B1 (de)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE977846C (de) * 1960-06-05 1971-09-02 Friedrich Dr Foerster Verfahren zur Kompensation der magnetischen Erdfeldstoerung durch Schiffe
GB8318111D0 (en) * 1983-07-04 1983-08-03 Secr Defence Magnetic assemblies
DE3403982A1 (de) * 1984-02-04 1985-08-08 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Verfahren fuer eine stoerfeldgeregelte magnetische eigenschutzanlage (smes-anlage)

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EP0623506A1 (de) 1994-11-09
FR2704829B1 (fr) 1995-06-09
FR2704829A1 (fr) 1994-11-10

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