DRONE FOR TRIGGERING NAVAL MINES, HAVING AN ELECTRIC DRIVE

Abstract

A drone for triggering naval mines, which drone includes a drive having an electric motor for locomotion in the water, wherein the electric motor can be used additionally to trigger the naval mines during operation of the drone, by an external magnetic field formed by the operation of the electric motor. The electric motor includes a stationary stator and a rotor, which is mounted for rotation relative to the stator. The stator includes at least one magnetic and/or electromagnetic element for forming an excitation field. The rotor includes at least one armature winding, which electromagnetically interacts with the excitation field during operation of the electric motor, whereby a superordinate magnetic field is formed. The external magnetic field formed outside of the electric motor during operation is in the form of a constant magnetic field.

Claims

1. A drone for triggering naval mines, comprising: a drive with an electric motor for locomotion in the water, wherein the electric motor is useable during operation of the drone for triggering the naval mines, by means of an external magnetic field formed by the operation of the electric motor, wherein the electric motor comprises a fixed stator and a rotor mounted rotatably in relation to the stator, wherein the stator has at least one magnetic and/or electromagnetic element for forming an excitation field, wherein the rotor has at least one armature winding, which during the operation of the electric motor interacts electromagnetically with the excitation field, whereby a superordinate magnetic field is formed, and wherein the external magnetic field formed during operation outside the electric motor is formed as a constant magnetic field.

2. The drone as claimed in claim 1, wherein the electric motor is formed in such a way that the rotor is arranged radially inside the stator.

3. The drone as claimed in claim 1, wherein the electric motor is formed in such a way that the stator is arranged radially inside the rotor.

4. The drone as claimed in claim 1, wherein the stator has a stator support and/or the rotor has a rotor support, wherein the magnetic properties of the stator support and/or the rotor support are designed in such a way that during the operation of the electric motor a magnetic flux of at least 0.5 mT can spread into a region outside the electric motor.

5. The drone as claimed in claim 4, wherein the stator support and/or the rotor support is formed at least in some portions from a material that has an effective permeability number μ.sub.r of at most 300.

6. The drone as claimed in claim 1, wherein the electric motor is designed as a DC motor.

7. The drone as claimed in claim 1, wherein the electric motor is designed as a synchronous motor.

8. The drone as claimed in claim 1, wherein the at least one element arranged in the stator for forming an excitation field is a permanent magnet.

9. The drone as claimed in claim 1, wherein the at least one element arranged in the stator for forming an excitation field is an electrical excitation coil.

10. The drone as claimed in claim 1, wherein the electric motor comprises at least one superconducting element.

11. The drone as claimed in claim 10, wherein the stator comprises at least one block of superconducting material impressed with a magnetic flux in such a way that the at least one block acts like a permanent magnet.

12. The drone as claimed in claim 10, wherein the stator comprises at least one block, wherein each block comprises in each case a plurality of stacked superconducting strip conductors, and wherein the respective block is impressed with a magnetic flux in such a way that the block acts like a permanent magnet.

13. The drone as claimed in claim 10, wherein the stator has at least one superconducting excitation coil.

14. The drone as claimed in claim 10, wherein the at least one armature winding has a superconducting electrical conductor.

15. The drone as claimed in claim 10, wherein the at least one superconducting element comprises a high-temperature superconducting material.

16. The drone as claimed in claim 5, wherein the stator support and/or the rotor support is formed at least in some portions from a material that has an effective permeability number μ.sub.r of at most 10.

17. The drone as claimed in claim 15, wherein the at least one superconducting element comprises a high-temperature superconducting material comprising magnesium diboride and/or a material of the type REBa.sub.2Cu.sub.3O.sub.x.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The invention is described below on the basis of several advantageous exemplary embodiments with reference to the appended drawings, in which:

[0054] FIG. 1 shows a drone 1 in a schematic longitudinal section and

[0055] FIGS. 2 to 5 show electric motors 3 by way of example in schematic cross section.

DETAILED DESCRIPTION OF INVENTION

[0056] In the figures, elements that are the same or functionally the same are provided with the same designations.

[0057] In FIG. 1, a drone 1 according to a first exemplary embodiment of the invention is shown in schematic longitudinal section. A drone of an elongated shape, designed for locomotion under water, is shown. It has in its rear part (shown on the left in the drawing) a propeller. The drone is therefore equipped with a drive system of its own, the propeller being driven here by way of a rotor shaft 7 of an electric motor 3. In the case of this exemplary embodiment, the electric motor 3 takes up a large part of the space available inside the drone. However, the space taken up by the electric motor 3 may in principle also end up being smaller, for example to provide space for a control unit for controlling the motor and other steering units for the drone that are not shown here. Furthermore, inside the drone there may also be an energy store, likewise not shown here, in the form of a battery or a fuel cell with a fuel supply. Alternatively, a fuel tank, for example a diesel tank, and a generator for supplying the motor with electrical energy may be provided. Or else the electric motor 3 may be supplied with electrical energy by way of an electric cable not shown here.

[0058] The electric motor 3 has a rotor 9, which is arranged on the rotor shaft 7 and is coupled to it in a torque-locking manner in such a way that the propeller 5 can be driven by way of the rotor shaft 7. The electric motor 3 also has a stator 11, which is arranged radially outside the rotor 9. Therefore, this is an internal-rotor motor. In the case of this motor, the external stator bears an exciter device, and the internal rotor bears an actuator winding. In principle, the motor may either be a DC motor or a synchronous motor, as will become even more clear in connection with FIGS. 2 to 4.

[0059] FIG. 2 shows a schematic cross section of such an electric motor 3 in a special exemplary embodiment of the drone. The external stator 11 surrounds the internal rotor 10 in the form of a ring, the rotor 10 being mounted rotatably about the central axis of rotation A. In this case, the internal rotor 10 comprises a rotor support 20. This rotor support 20 has in the region of its outer surface a plurality of armature slots 19, in which an armature winding 18 is embedded. In the radially further inner-lying region of the electric motor, brushes 27 for electrical contact with fixed power supply lines are also provided. Also arranged here is a commutator 25, which acts as a mechanical inverter, so that a direct voltage on the fixed power supply lines periodically changes its sign within the rotor. The brushes 27 and the commutator 25 do not necessarily have to be arranged at the same axial position as the other components that are shown in FIG. 2. They may possibly also be arranged axially offset in relation to the armature winding. The representation of FIG. 2 should be understood as only extremely schematic with respect to these elements.

[0060] The external stator 11 comprises a stator support 21, which has a circular-cylindrical outer contour. This stator support bears an exciter device, which in the example shown is designed for forming a two-pole magnetic field. The number of pairs of poles p here is therefore p=1. In this example, the exciter device comprises two excitation coils 14, which are arranged on pole supports 16 of the stator lying opposite one another. These pole supports 16 are in each case shaped radially inward to form pole shoes and additionally bear in each case a compensating coil 17 in the region of these pole shoes. Furthermore, the stator support 21 has between the two pole supports 16 in the circumferential direction two commutating pole supports 22, on which a commutating pole coil 23 is in each case arranged. The compensating coils 17 and commutating pole coils 23 in this case assist the spatial shaping of the magnetic excitation field generated overall by the exciter device (and in particular the excitation coils 14). The magnetic excitation field generated in this way in turn interacts electromagnetically with the internal rotor 10, and in particular with the armature winding 18 arranged on it. This electromagnetic interaction has the effect in particular of bringing about a conversion of electrical energy into the mechanical energy of the rotation within the electric motor 3. In addition, this electromagnetic interaction also has the effect of influencing the magnetic excitation field, so that overall a superordinate magnetic field B of the electric machine is obtained.

[0061] In the case of the electric motor 3 of the exemplary embodiment shown, the stator support 21 is formed completely from an amagnetic material, for example an amagnetic steel. As a result, as a difference from electric motors that are typically used, the magnetic flux is not enclosed within the motor in the form of a ring. This advantageously brings about the effect that the magnetic flux formed can spread out radially far into regions outside the stator and be used there for triggering magnetic mines. The radially further inner-lying rotor support 20 may optionally either also be formed from an amagnetic material or else it may also be formed from a soft-magnetic material for the magnetic flux guidance within the rotor. Soft-magnetic materials in the radially inner region of the rotor 10 do not prevent the magnetic field from spreading into the radially further outer-lying regions outside the electric motor.

[0062] In FIG. 3, a scaled-down representation of the electric motor 3 from the example of FIG. 2 is shown, an outer motor housing 13 also being shown in addition to the previously described components. Furthermore, a field line is shown by way of example for the superordinate magnetic field B that is formed by the interaction of the rotor and the stator. This magnetic field B also spreads into the regions outside the motor housing 13 and is correspondingly denoted there by B.sub.ext. Since the magnetic field B.sub.ext present outside the electric motor is provided essentially by the excitation field of the fixed stator and is only slightly influenced by the interaction with the rotating rotor, this is a constant magnetic field. However, the amplitude may vary periodically due to the influence of the rotor.

[0063] The motor housing 13 has here a rectangular cross section. As an alternative to this, it may however also have a round, in particular circular, cross section, or at least the cross section may have rounded corners or be formed as a polygon with more than four corners, in order that the electric motor 3 takes up less space inside the drone. The electric motor 3 is in any case designed overall in such a way that an external magnetic field B.sub.ext with a magnetic flux density suitable for triggering naval mines can also be generated outside the motor housing 13. It is therefore intended to be an electric motor 3 with overall particularly weak shielding.

[0064] FIG. 4 shows an electric motor 3 according to a further example of the invention in schematic cross section. This electric motor is also designed as a DC motor. Here, too, a commutator 25 is provided inside the electric motor—possibly at a different axial position—as well as brush contacts, which for the sake of overall clarity are not shown in FIG. 4. As a difference from the example of FIGS. 2 and 3, instead of excitation coils, the stator 11 of this electric motor is equipped with a plurality of permanent magnets 15 as an exciter device. In the example shown, these are four permanent magnets 15, which are arranged on the inside of the stator support 21. The permanent magnets 15 are distributed uniformly over the circumference of the stator and alternate in their radial orientation of the magnetic north pole N and magnetic south pole S. Here, too, the four-pole excitation field (p=2) formed in this way interacts electromagnetically with the armature winding 18 arranged on the rotor support 20 of the rotor 10. In a way similar to in the case of the example of FIGS. 2 and 3, here, too, the stator support 21 is formed from an amagnetic material. In this way it is achieved that the magnetic field B formed overall by the electric machine 3 can spread out far, and a strong external constant magnetic field B.sub.ext suitable for triggering naval mines is also generated outside the electric motor.

[0065] FIG. 5 shows an electric motor 3 according to a further exemplary embodiment of the invention. The overall construction of the electric motor is similar to in the case of the previous example. Thus, here, too, an external stator 11 is arranged radially around an internal rotor 10, the stator 11 bearing an exciter device comprising four permanent magnets 15 and the rotor 10 bearing an armature winding 18. Here, too, the stator support 21 is formed from an amagnetic material, so that the superordinate magnetic field B of the machine can spread out far. As a difference from the example of FIG. 4, however, here the electric motor 3 is designed as a synchronous motor and not as a DC motor. Correspondingly, the commutator is absent here, and the armature winding 18 of the rotor 10 is connected to an alternating current source that is not shown here. Such an alternating current source may for example also be formed by a combination of a direct current source and an inverter.

[0066] The permanent magnets 15 from the examples of FIGS. 4 and 5 may be formed either as classic permanent magnets (in particular with rare earth materials) or else as superconducting permanent magnets. In this way, particularly strong magnetic fields can be obtained. In the case of the example of FIGS. 2 and 3, the excitation winding with the excitation coils 14 can be realized as a superconducting excitation winding.

LIST OF DESIGNATIONS

[0067] 1 Drone [0068] 3 Electric motor [0069] 5 Propeller [0070] 7 Rotor shaft [0071] 10 Rotor [0072] 11 Stator [0073] 13 Motor housing [0074] 14 Excitation coil [0075] 15 Permanent magnet [0076] 16 Pole support [0077] 17 Compensating coil [0078] 18 Armature winding [0079] 19 Armature slot [0080] 20 Rotor support [0081] 21 Stator support [0082] 22 Commutating pole support [0083] 23 Commutating pole coil [0084] 25 Commutator [0085] 27 Brush [0086] A Axis of rotation [0087] B Magnetic field [0088] B.sub.ext External magnetic field [0089] N North pole [0090] S South pole