REDUNDANT ELECTRICAL MACHINE FOR DRIVING A MEANS OF PROPULSION

Abstract

The invention relates to an in particular redundant electrical machine for driving a propulsion means with improved protection against failure. The machine includes for example two submachines consisting in each case of a stator winding system and a rotor, wherein the two rotors are arranged on a common shaft in a rotationally fixed manner, by way of which shaft the propulsion means is ultimately set in motion. Also provided is a movement device which has the effect, in the case of a fault in one of the stator winding systems, that the air gap between the stator winding system in question and the associated rotor is increased for the corresponding faulty submachine such that the electromagnetic interaction between these components is suppressed.

Claims

1. A redundant electrical machine for driving a propulsion means, having a drive system, wherein the drive system has a stator arrangement having at least two stator winding systems, rotor arrangement having at least one rotor, wherein each rotor has at least one permanent magnet, and wherein each stator winding system is assigned one of the rotors, wherein a respective stator winding system and the rotor assigned thereto are arranged with respect to one another so as to form a respective air gap between one another, such that the respective stator winding system and the permanent magnet of the rotor assigned to the respective stator winding system are able to interact electromagnetically with one another across the respective air gap during normal operation of the electrical machine, and wherein the electrical machine has a movement device for mutually moving the faulty stator winding system and the rotor assigned thereto out of a normal position for a case of a fault that occurs in a faulty one of the two stator winding systems, wherein the movement device is designed such that, by virtue of the movement out of the normal position, the air gap between the faulty stator winding system and the rotor assigned thereto is increased.

2. The redundant electrical machine as claimed in claim 1, wherein the movement device is designed such that the movement is oriented in an axial direction.

3. The redundant electrical machine as claimed in claim 1, wherein the movement device has: a mechanical means, by way of which a force required for the movement is able to be provided to the faulty stator winding system and/or to the rotor assigned thereto in the case of a fault, a releasable latch that has the effect that the mechanical means exerts the force only when the case of a fault is present after the latch has been released, but not during normal operation of the electrical machine.

4. The redundant electrical machine as claimed in claim 3, wherein the mechanical means extends between two ends, wherein one of the ends is attached to a fixed point outside of the drive system and the other end is attached to the stator winding system to be moved or to the rotor to be moved.

5. The redundant electrical machine as claimed in claim 3, wherein the mechanical means extends between two ends, wherein one of the ends is attached to the respective stator winding system and the other end is attached to the rotor assigned to this stator winding system.

6. The redundant electrical machine as claimed in claim 3, wherein the mechanical means has at least one spring device, wherein a rotor and at least one of the spring devices are respectively assigned to one another, wherein each rotor is mechanically connected to the spring device assigned thereto, such that the mechanical means is able to apply the force to the respective rotor, the respective spring device is preloaded in the normal position and during normal operation and set by way of the latch such that it exerts the force on the rotor assigned thereto in the case of a fault when the latch is released, wherein the force has a component in the axial direction such that the respective rotor is moved in the axial direction when the latch is released.

7. The redundant electrical machine as claimed in claim 1, wherein a shaft is provided for transferring a drive power provided by the respective rotor to the propulsion means, wherein each of the rotors is able to be rotated with respect to the stator winding systems, is connected in a rotationally fixed manner to the shaft such that it is able to be moved in the axial direction with respect to the shaft.

8. The redundant electrical machine as claimed in claim 3, wherein the mechanical means has at least one spring device, wherein a stator winding system and at least one of the spring devices are respectively assigned to one another, wherein each stator winding system is mechanically connected to the spring device assigned thereto, such that the mechanical means is able to apply the force to the respective stator winding system, the respective spring device is preloaded in the normal position and during normal operation and set by way of the latch such that it exerts the force on the stator winding system assigned thereto in the case of a fault when the latch is released, wherein the force has a component in the axial direction such that the respective stator winding system is moved in the axial direction when the latch is released.

9. The redundant electrical machine as claimed in claim 1, wherein the machine is an axial flux machine in which the rotor is arranged between the stator winding systems as seen in the axial direction, wherein the movement device is designed and arranged such that it moves the faulty stator winding system in the axial direction away from the rotor in the case of a fault, such that the respective air gap between the moved faulty stator winding system and the rotor assigned thereto increases, whereas the air gap between the non-faulty stator winding system and the rotor assigned thereto remains unchanged.

10. The redundant electrical machine as claimed in claim 1, wherein the machine is an axial flux machine, wherein the rotor arrangement has at least one further rotor, wherein one of the stator winding systems and one of the rotors are in each case assigned to one another so as to form a respective electrical submachine, a respective stator winding system and the rotor assigned thereto are arranged behind one another as seen in the axial direction and so as to form an air gap between one another, the submachines are arranged far enough apart from one another as seen in the axial direction that the rotor of one submachine does not interact electrically with the stator winding system of the respective other submachine, wherein the movement device is designed and arranged such that it moves the faulty stator winding system and/or the rotor, assigned thereto, of the faulty submachine away from one another in the axial direction in the case of a fault, such that the air gap of the faulty submachine increases, whereas the air gap between the non-faulty stator winding system and the rotor assigned to this stator winding system remains unchanged.

11. The redundant electrical machine as claimed in claim 1, wherein the machine is a radial flux machine, wherein the rotor arrangement has at least one further rotor, wherein one of the stator winding systems and one of the rotors are in each case assigned to one another so as to form a respective electrical submachine, a respective stator winding system and the rotor assigned thereto are arranged at a substantially identical position as seen in the axial direction in the normal position, such that the respective air gap is between the respective stator winding system and the rotor assigned thereto in the radial direction, the submachines are arranged far enough apart from one another as seen in the axial direction that the rotor of one submachine does not interact electrically with the stator winding system of the respective other submachine, wherein the movement device is designed and arranged such that it moves the faulty stator winding system and/or the rotor, assigned thereto, of the faulty submachine away from one another in the axial direction in the case of a fault, such that the air gap of the faulty submachine increases, whereas the air gap between the non-faulty stator winding system and the rotor assigned to this stator winding system remains unchanged.

12. The redundant electrical machine as claimed in claim 11, wherein each of the stator winding systems has magnetically active regions, in particular stator electrical metal sheets, that each extend over a first region as seen in the axial direction, wherein the rotor assigned to the respective stator winding system, in particular the permanent magnet thereof, extends over a second region in the axial direction, wherein a respective stator winding system and the rotor assigned thereto are arranged in the normal position such that one of the two regions completely comprises the respective other region, the movement device is designed such that the mutual movement in the case of a fault is at least such that the first region of the axial extent of the faulty stator winding system and the second region of the axial extent of the rotor assigned thereto no longer overlap after the movement.

13. The redundant electrical machine as claimed in claim 11, wherein each of the stator winding systems has magnetically active regions, in particular stator electrical metal sheets, that each extend over a first region as seen in the axial direction, wherein the rotor assigned to the respective stator winding system, in particular the permanent magnet thereof, extends over a second region in the axial direction, wherein a respective stator winding system and the rotor assigned thereto are arranged in the normal position such that one of the two regions completely comprises the respective other region, the movement device is designed such that the mutual movement in the case of a fault is only such that the first region of the axial extent of the faulty stator winding system and the second region of the axial extent of the rotor assigned thereto still overlap after the movement, but one of the two regions no longer completely comprises the other region as seen in the axial direction.

14. The redundant electrical machine as claimed in claim 11, wherein each of the rotors is formed conically such that a radius of a respective rotor changes continuously or incrementally with a height of the rotor extending in the axial direction between the axial ends of the respective rotor, each of the stator winding systems is formed, in accordance with the conical form of the rotor assigned thereto, such that the radial extent of the respective air gap between the respective stator winding system and the rotor assigned thereto is substantially identical in the normal position at each point of the height of the respective rotor.

15. The redundant electrical machine as claimed in claim 14, wherein, for each rotor, the radius is at a maximum at that axial end of the respective rotor that faces the respective other rotor.

Description

[0041] In the figures:

[0042] FIG. 1 shows a permanently excited electrical machine,

[0043] FIG. 2 shows a first variant of a first embodiment of an electrical machine during normal operation,

[0044] FIG. 3 shows the first variant of the first embodiment of the electrical machine in the case of a fault,

[0045] FIG. 4 shows a second variant of the first embodiment of the electrical machine during normal operation,

[0046] FIG. 5 shows the second variant of the first embodiment of the electrical machine in the case of a fault,

[0047] FIG. 6 shows a third variant of the first embodiment of the electrical machine during normal operation,

[0048] FIG. 7 shows the third variant of the first embodiment of the electrical machine in the case of a fault,

[0049] FIG. 8 shows a first variant of a second embodiment of the electrical machine during normal operation,

[0050] FIG. 9 shows the first variant of the second embodiment of the electrical machine in the presence of a case of a fault,

[0051] FIG. 10 shows a second variant of the second embodiment of the electrical machine in the presence of a case of a fault,

[0052] FIG. 11 shows a third variant of the second embodiment of the electrical machine during normal operation,

[0053] FIG. 12 shows the third variant of the second embodiment of the electrical machine in the presence of a case of a fault,

[0054] FIG. 13 shows the first variant of the second embodiment during normal operation and with a movement device,

[0055] FIG. 14 shows the first variant of the second embodiment in the presence of a case of a fault and with the movement device.

[0056] It is pointed out that terms such as axial and radial relate to the shaft or axle used in the respective figure or in the respectively described example. In other words, the directions axial and radial always relate to an axis of rotation of the respective rotor.

[0057] A component in which a case of a fault occurs is consequently referred to hereinafter as faulty component.

[0058] FIG. 1 shows, merely to explain the basic operation or the fundamental concept, an overview of a simple, permanently excited electrical machine 100. The machine 100 has a rotor 110 with permanent magnets 130 and a stator 120 with a stator winding system or stator coils 140. The rotor 110 attached to a shaft 150 is able to be rotated with the shaft 150 about an axis of rotation A with respect to the stator 120. In the operating state of the electrical machine 100, the rotor 110 rotates with respect to the stator 120. The rotor 110 and the stator 120 are arranged with respect to one another such that a magnetic field of the permanent magnets 130 and the coils 140 interact electromagnetically with one another such that the electrical machine 100 operates in a first operating mode as a generator and/or in a second operating mode as an electric motor due to the interaction. If the electrical machine 100 operates as a generator, then the rotor 110 and, with it, the permanent magnets 130 are set in rotation by way of the shaft 150 of the electrical machine 100, such that electric voltages are induced in the coils 140 of the stator 120, these electric voltages being able to be tapped off via electrical terminals that are not illustrated. If the electrical machine 100 is intended to operate as an electric motor and for example drive a propeller, then an electric current is applied to the coils 140 such that, due to the interaction of the magnetic fields generated thereby with the fields of the permanent magnets 130, a torque acts on the rotor 110 and therefore on the shaft 150, which torque is able to be forwarded to the device to be driven, for example the propeller.

[0059] In developments of the electrical machine 100, said electrical machine may be designed as an axial flux machine or as a radial flux machine, this however not having any influence on the basic operation that has just been described. The machine 100 may likewise have a plurality of rotors and/or a plurality of stators in order, for example, to increase redundancy, that is to say a plurality of drive subsystems, and/or the rotor or the stator may be designed as a single or dual rotor or single or dual stator. In all of these cases, the basic concept of the electrical machine however remains applicable. It is in particular the case in all cases that the efficiency of said electromagnetic interaction and thus ultimately the power density of the electrical machine depends on the extent of what is known as the air gap between the mutually interacting permanent magnets and stator coils or between mutually assigned rotor and stator. In this case, the efficiency increases as the air gap becomes smaller, that is to say an air gap that is as narrow or small as possible is beneficial during normal operation. By contrast, the efficiency drops as the air gap becomes larger, until the distance between stator and rotor is so great that the electromagnetic interaction becomes so low that virtually no voltage is induced any more in the stator coils, in spite of the rotating rotor.

[0060] Since the basic operation of an electrical machine 100 is known, a more extensive explanation is not provided at this point.

[0061] For the sake of clarity, the illustration of the permanent magnets and of the stator coils is not given in the following figures. By contrast, only rotors or stators are illustrated without further detail, it being able to be assumed that the illustrated rotors have a multiplicity of permanent magnets and the stators have a multiplicity of stator winding systems or stator coils, such that mutually assigned rotors and stators or their permanent magnets and winding systems are able to interact electromagnetically with one another in order to operate the electrical machine 10 as an electric motor or as a generator. It should furthermore be assumed in this case that, in the case that the rotor is designed as a dual rotor having two sub-rotors, the permanent magnets are arranged on the sub-rotors. In the case that the rotor is designed as a single rotor, the permanent magnets are consequently located on the single rotor. The same applies to the stator: If said stator is designed as a dual stator with two sub-stators, the stator winding systems are located on the sub-stators. In the case of a single stator, the stator winding systems are arranged on this single stator. Independently of the design of the rotor and of the stator, it is the case in all embodiments and variants that each rotor is able to be rotated with respect to the respectively associated stator. In this case, the rotors are connected in a rotationally fixed manner to the shaft, for example by way of a corresponding tooth system. All of the rotors and stators are furthermore arranged concentrically with respect to one another and to the respective shaft.

[0062] In the first embodiment, the electrical machine 10 is designed as an axial flux machine, that is to say in particular that the rotor and the stator are arranged behind one another in the axial direction and the magnetic flux runs between the rotor and the stator in the substantially axial direction.

[0063] FIG. 2 shows a first variant of the first embodiment during normal operation, in which the machine 10 has a first drive subsystem 200 and, for redundancy purposes, also has a second drive subsystem 300. Each of the drive subsystems 200, 300 comprises a dual rotor 210, 310 having sub-rotors 211, 212, respectively 311, 312 able to be moved on the shaft 150 in the axial direction, and a stator 220, 320, wherein the stators 220, 320 are each arranged between the sub-rotors 211, 212, respectively 311, 312 of the respective drive subsystem 200, 300 in the axial direction.

[0064] The first dual rotor 210 and the first stator 220 are assigned to one another and designed during normal operation of the machine 10 and arranged with respect to one another so as to form air gaps 231, 232 between one another such that they are able to interact electromagnetically with one another.

[0065] The second dual rotor 310 and the second stator 320 are likewise assigned to one another and designed during normal operation of the machine 10 and arranged with respect to one another so as to form air gaps 331, 332 between one another such that they are able to interact electromagnetically with one another.

[0066] Both the first 210 and the second dual rotor 310 or the sub-rotors 211, 212, 311, 312 are connected in a rotationally fixed manner to a shaft 150. If the drive subsystems 200, 300 operate as electric motors, the shaft 150 is driven by the dual rotors 210, 220, such that a propulsion means (not illustrated) connected to the shaft 150, for example a propeller, is able to be set in rotation.

[0067] FIG. 3 shows the first variant of the first embodiment in the presence of a case of a fault in the stator winding system of the stator 220 of the first drive subsystem 200. As is able to be clearly seen, a device 400, not yet illustrated here, has been used to achieve the effect whereby the air gaps 231, 232 between the first stator 220 and the sub-rotors 211, 212 have been increased to the extent that the electromagnetic interaction between the first stator 220 and the sub-rotors 211, 212 is suppressed, that is to say the first dual rotor 210 is magnetically decoupled from the faulty stator 220. Although the shaft 150 and, with it, the sub-rotors 211, 212 thus rotate, in particular due to the second drive subsystem 300, which continues to operate as an electric motor, on account of the increased air gaps 231, 232, no voltages are induced in the stator winding system of the first stator 220, as a result of which the risk of fire is reduced to a minimum or virtually ruled out. Furthermore, in spite of the failure of the first drive subsystem 200, the propulsion means is still able to be operated, just with reduced efficiency. Redundancy is thus provided in this variant.

[0068] FIG. 4 shows a second variant of the first embodiment during normal operation, in which the machine 10 likewise has a first 200 and, for redundancy purposes, also has a second drive subsystem 300. Each of the drive subsystems 200, 300 comprises a rotor 210, 310 able to be moved on the shaft 150 in the axial direction, in particular designed as a single rotor 210, 310, and a stator 220, 320. The second variant of the first embodiment differs from the first variant only in that the rotors 210, 310 are not designed here as dual rotors.

[0069] The rotors 210, 310 and the stators 220, 320 of the respective drive subsystem 200, 300 are also assigned to one another in this variant and designed during normal operation of the machine 10 and arranged with respect to one another so as to form air gaps 231, 331 between one another such that they are able to interact electromagnetically with one another. During normal operation, the drive subsystems 200, 300 thus operate such that they both set the shaft 150 in rotation by way of their rotor 210, 310.

[0070] FIG. 5 shows the second variant of the first embodiment in the presence of a case of a fault in the stator winding system of the stator 220 of the first drive subsystem 200. Similarly to in the first variant, the device 400, likewise not illustrated here, has been used to achieve the effect whereby the air gap 231 between the first stator 220 and the first rotor 210 has been increased to the extent that the electromagnetic interaction between the first stator 220 and the rotor 210 is suppressed, that is to say the first rotor 210 is magnetically decoupled from the faulty stator 220. It is the case here too that, on account of the increased air gap 231, no voltages are able to be induced in the stator winding system of the first stator 220, as a result of which the risk of fire is reduced to a minimum or virtually ruled out, even though, in particular due to the second drive subsystem 300, which is still operating as an electric motor, the shaft 150 and, with it, the rotor 210 rotate. Furthermore, in spite of the failure of the first drive subsystem 200, the propulsion means is still able to be operated, just with reduced efficiency. Redundancy is thus also provided in this variant.

[0071] FIG. 6 shows a third variant of the first embodiment of the electrical machine 10 during normal operation. The machine 10 has a drive system 200 that is already redundant in and of itself, comprising a rotor 210, in particular a single rotor, and a dual stator 220 having sub-stators 221, 222 able to be moved on the shaft 150 in the axial direction. The rotor 210 is arranged between the sub-stators 221, 222 in the axial direction.

[0072] The rotor 210 and the stator 220 of the drive system 200 are also assigned to one another in this third variant of the first embodiment and designed during normal operation of the machine 10 and arranged with respect to one another so as to form air gaps 231, 331 between one another such that they are able to interact electromagnetically with one another. During normal operation, the drive system 200 thus operates such that it sets the shaft 150 in rotation by way of the rotor 210.

[0073] FIG. 7 shows the third variant of the first embodiment in the presence of a case of a fault in the stator winding system of the sub-stator 221. In this case too, the device 400, likewise not illustrated here, has been used to achieve the effect whereby the air gap 231 between the sub-stator 221 and the rotor 210 has been increased to the extent that the electromagnetic interaction between the sub-stator 221 and the rotor 210 is suppressed, that is to say the rotor 210 is magnetically decoupled from the faulty first sub-stator 221. Due to the larger air gap 231, no voltages are able to be induced in the stator winding system of the sub-stator 221, even though the rotor 210 continues to rotate due to its interaction with the intact sub-stator 222. Due to this rotation, the shaft 150 and, with it, the propulsion means is driven, even in spite of the case of a fault in the sub-stator 221, again just with reduced efficiency. Redundancy is thus also provided in this variant.

[0074] The following FIGS. 8 to 12 relate to a second embodiment of the electrical machine 10. In the variants of the second embodiment, the machine 10 is designed as a radial flux machine, that is to say in particular that a rotor and a stator that are assigned to one another and interact with one another during normal operation are arranged at substantially the same position in the axial direction, but that the stator is arranged radially outside the rotor (also vice versa in theory). The magnetic flux between the rotor and the stator runs in the substantially radial direction.

[0075] In the figures with regard to the variants of the second embodiment, the winding heads 225, 325 that are typically present are also illustrated for the respective stators 220, 320. The stators 220, 320 furthermore each have stator electrical metal sheets 226, 326. Due to the space required by the winding heads 225, 325, there is a space, in the axial direction between the stator electrical metal sheets 226, 326 of the two stators 220, 320, in which no electrical metal sheet is present. As shown below, this space is required in order to move a respective rotor 210, 310.

[0076] FIG. 8 shows a first variant of the second embodiment during normal operation. The machine 10 has a first drive subsystem 200 and, for redundancy purposes, also has a second drive subsystem 300. Each of the drive subsystems 200, 300 comprises a rotor 210, 310 able to be moved on the shaft 150 in the axial direction and a stator 220, 320.

[0077] The first rotor 210 and the first stator 220 are assigned to one another and designed during normal operation of the machine 10 and arranged with respect to one another so as to form an annular or cylindrical air gap 231 between one another such that they are able to interact electromagnetically with one another.

[0078] The second rotor 310 and the second stator 320 are likewise assigned to one another and designed during normal operation of the machine 10 and arranged with respect to one another so as to form an annular or cylindrical air gap 331 between one another such that they are able to interact electromagnetically with one another.

[0079] If the drive subsystems 200, 300 operate as electric motors, the shaft 150 is driven by the rotors 210, 220 such that a propulsion means (not illustrated) connected to the shaft 150, for example a propeller, is able to be set in rotation.

[0080] FIG. 9 shows the first variant of the second embodiment in the presence of a case of a fault in the stator winding system of the stator 220 of the first drive subsystem 200. As is able to be clearly seen, the device 400, not illustrated here, has been used to achieve the effect whereby the rotor 210 assigned to the faulty stator 220 has been moved in the axial direction. In this first variant of the second embodiment, the rotor 210 is in particular moved to the extent that it moves out of the region within the stator electrical metal sheet 226 into the region underneath the winding heads 225, 325. The movement has the effect that the air gap 231 or the distance between the faulty stator 220 and the rotor 210 has increased to the extent that the electromagnetic interaction between the first stator 220 and the rotor 210 is suppressed, that is to say the first rotor 210 is magnetically decoupled from the faulty stator 220. Although the shaft 150 and, with it, the rotor 210 thus rotate, in particular due to the second drive subsystem 300, which continues to operate as an electric motor, on account of the increased air gap 231 or distance, no voltages are induced in the stator winding system of the first stator 220, as a result of which the risk of fire is reduced to a minimum or virtually ruled out. Furthermore, in spite of the failure of the first drive subsystem 200, the propulsion means is still able to be operated, just with reduced efficiency. Redundancy is thus provided in this variant.

[0081] In this first variant of the second embodiment, and likewise in the second variant to be described below, the air gap is strictly speaking not only increased, but rather the original geometry of the air gap is lost. In spite of this, reference is also made to an increase in the air gap in this connection, this in particular however meaning, in connection with the radial flux machine, that the distance between the rotor and the assigned stator is increased. Independently of the terminology, it should be assumed that the loss of the geometry of the air gap, in addition to the pure increase in the distance, has an essential influence on reducing the electromagnetic interaction.

[0082] FIG. 10 shows a second variant of the second embodiment that corresponds to the first variant of the second embodiment apart from the detail that, in the second variant, the space into which the rotor 210, 310 is able to be moved in the case of a fault has a smaller extent in the axial direction. This may for example be due to restricted spatial conditions. Due to the similarity between the variants, no explanation is given of this second variant for normal operation. FIG. 10 therefore shows the second variant of the second embodiment in the presence of a case of a fault in the stator winding system of the stator 220 of the first drive subsystem 200. The assigned rotor 210 has been moved in the axial direction. In this second variant of the second embodiment, the rotor 210 is however only moved to the extent that it still protrudes partly into the region within the stator electrical metal sheet 226. In this case, although the electromagnetic interaction between the rotor 210 and the stator 220 is still greater than in the first variant, it is possible to assume cases in which it is actually not necessary to completely remove the rotor 210 from said region. In this case, the abovementioned topic also continues to play a role in that the geometry of the air gap 231 is also changed greatly in the first and second variant.

[0083] The movement thus has the effect that the air gap 231 or the distance between the faulty stator 220 and the rotor 210 has increased to the extent that the electromagnetic interaction between the first stator 220 and the sub-rotors 211, 212 has been reduced to a sufficient extent, that is to say the first rotor 210 is magnetically decoupled from the faulty stator 220. Although the shaft 150 and, with it, the rotor 210 thus rotate, in particular due to the second drive subsystem 300, which continues to operate as an electric motor, on account of the increased air gap 231 or distance, no voltages are induced in the stator winding system of the first stator 220, as a result of which the risk of fire is reduced to a minimum or virtually ruled out. Furthermore, in spite of the failure of the first drive subsystem 200, the propulsion means is still able to be operated, just with reduced efficiency. Redundancy is thus provided in this variant.

[0084] FIG. 11 shows a third variant of the second embodiment during normal operation. The machine 10 has a first drive subsystem 200 and, for redundancy purposes, also has a second drive subsystem 300. Each of the drive subsystems 200, 300 comprises a rotor 210, 310 able to be moved on the shaft 150 in the axial direction and a stator 220, 320.

[0085] The first rotor 210 and the first stator 220 are assigned to one another and designed during normal operation of the machine 10 and arranged with respect to one another so as to form an air gap 231 between one another such that they are able to interact electromagnetically with one another.

[0086] The second rotor 310 and the second stator 320 are likewise assigned to one another and designed during normal operation of the machine 10 and arranged with respect to one another so as to form an air gap 331 between one another such that they are able to interact electromagnetically with one another.

[0087] If the drive subsystems 200, 300 operate as electric motors, the shaft 150 is driven by the rotors 210, 220 such that a propulsion means (not illustrated) connected to the shaft 150, for example a propeller, is able to be set in rotation.

[0088] Unlike the other variants of the second and also the first embodiment, the rotors 210, 310 in the third variant are not substantially cylindrical, but rather they have a conical form. The rotors 210, 310 are thus distinguished in that their radii RL are not constant, but rather change with the height of the respective rotor 210, 310, the height extending in the axial direction. The form of the rotors 210, 310 is in particular such that the radius RLi is at a maximum on that side of the respective rotor 210, 310 that faces the respective other rotor 310, 210. The radius RLa is accordingly at a minimum on the respective other side of the respective rotor 210, 310. In the region between the two ends of the respective rotor 210, 310, the radius RL from one to the other side of the respective rotor 210, 310 changes continuously or else, as illustrated in FIG. 11, incrementally.

[0089] The stators 220, 320 are formed, in accordance with the conical form of the rotors 210, 310, such that the radial extent of the air gaps 231, 331 is identical everywhere, that is to say at each point of the height of the respective rotor 210, 310, in particular during normal operation. The stators 220, 320 designed as hollow bodies in the embodiments illustrated here are also accordingly distinguished in that their inner radii RS are not constant, but rather change with the height of the respective stator 220, 320. In this case, the heights of the stators 220, 320 also extend in the axial direction. The form of the stators 220, 320 is in particular such that the inner radius RSi is at a maximum on that side of the respective stator 220, 320 that faces the respective other stator 320, 220. The inner radius RSa is accordingly at a minimum on the respective other side of the respective stator 220, 320. In the region between the two ends of the respective stator 220, 320, the inner radius RS from one to the other side of the respective stator 220, 320 changes continuously or else, as illustrated in FIG. 11, incrementally. The stators 220, 320 are thus formed such that they have a form matching the conical form of the respectively assigned rotor 210, 310, in particular on their inner side, that is to say are likewise conical.

[0090] The above description applies in particular to the illustrated case in which the rotors 210, 310 are designed as internal rotors. In one alternative design that is however not illustrated and in which the rotors are designed as external rotors, the arrangement would be the same as the arrangement illustrated in FIG. 11, but in this case the rotors would be designed as hollow bodies and their inner radii would be accordingly matched to the conical form of the radially inner stator such that the respective air gap is constant.

[0091] During normal operation, it is accordingly the case for both drive subsystems 200, 300 that: RS(h)=RL(h)+L, wherein h indicates the position in the axial direction and L describes the extent of the air gap 231, 331 in the radial direction.

[0092] FIG. 12 shows the third variant of the second embodiment in the presence of a case of a fault in the stator winding system of the stator 220 of the first drive subsystem 200. As is able to be clearly seen, the device 400, not illustrated here, has been used to achieve the effect whereby the assigned rotor 210 has been moved in the axial direction such that, on account of the conical form of the rotor 210 and of the stator 220, the air gap 231 increases such that the electromagnetic interaction between the first stator 220 and the rotor 210 is suppressed, that is to say the first rotor 210 is magnetically decoupled from the faulty stator 220. Although the shaft 150 and, with it, the rotor 210 thus rotate, in particular due to the second drive subsystem 300, which continues to operate as an electric motor, on account of the increased air gap 231 or distance, no voltages are induced in the stator winding system of the first stator 220, as a result of which the risk of fire is reduced to a minimum or virtually ruled out. Furthermore, in spite of the failure of the first drive subsystem 200, the propulsion means is still able to be operated, just with reduced efficiency. Redundancy is thus provided in this variant.

[0093] The particular advantage of the third variant with conical rotors 210, 310 and accordingly formed stators 220, 320 is that the respective rotor 210, 310 has to be moved to a significantly lesser extent in order to significantly increase the respective air gap 231, 331 in the case of a fault. That is to say, the geometry proposed in the third variant is advantageous in particular in the case of constricted spatial conditions.

[0094] In the embodiments or variants in which a plurality of stators or sub-stators are provided, it should be assumed that the individual stators or sub-stators are electrically insulated such that a fault in one stator or sub-stator is not able to propagate to the respective other stator or sub-stator.

[0095] FIG. 13 shows, with reference to the example of the first variant of the second embodiment during normal operation, a device 400 by way of which the rotor 210, 310 are able to be moved in the axial direction. For each rotor 210, 310, the device 400 has a mechanical means 411, 421, for example mechanical springs, by way of which a respective force is able to be applied to the rotors 210, 310 to be moved. The springs 411, 421 are attached, at one end 412, 422, for example to a casing part 11 of the electrical machine 10. As an alternative, the ends 412, 422 could be attached to another fixed object, for example to the winding heads 225, 325. The respective other end 413, 423 of the springs 411, 421 is attached to the respective rotor 210, 310, preferably to a component 215, 315 of the respective rotor 210, 310 that does not jointly rotate, but rather remains stationary with respect to the casing 11. The springs 411, 421 are in this case arranged and oriented such that they are each able to exert a force that has at least one component in the axial direction, such that the respective rotor 210, 310 is possibly able to be moved on account of the force. For this purpose, the springs 411, 421 are in particular preloaded during normal operation, but the mechanical latches 414, 424 have the effect that the springs 411, 421 are prevented from relaxing and exerting the energy stored or force retained on account of the preloading. The latches may be installed at a wide variety of locations depending on the design and arrangement of the springs 411, 421. By way of example, as indicated in FIG. 13, they may create fixed connections between the casing 11 and the component 215, 315. As an alternative, the latches could also be designed for example as trigger pins.

[0096] In the case of a fault, the respective mechanical means 411 or 421, that is to say the corresponding springs 411, 421, are activated by releasing the respective latch 414, 424, such that the corresponding springs 411, 421 relax and are able to exert the force on the respective rotor 210, 310, such that said rotor is moved.

[0097] FIG. 14 shows, with reference to the example of the first variant of the second embodiment, the device 400 in the case of a fault. The latches 414 are released such that the springs 411 are able to relax, resulting in a force on the rotor 210. This has accordingly been moved, as illustrated in FIG. 14 and as already explained in connection with FIG. 10.

[0098] The latches may be released for example by a controller 500 that monitors the drive subsystems 200, 300 at least with regard to the occurrence of a case of a fault and initiates releasing of the corresponding latch 414 or 424 upon detecting such a situation.

[0099] The device 400 described in connection with FIGS. 13 and 14 and in particular the mechanical means 411, 421 may of course be implemented in a wide variety of designs, the described spring being one possible design from among said designs. This has been explained above in a configuration as a compression spring, but it may also of course be configured as a tension spring in a corresponding arrangement. Other implementations of the mechanical means 411, 421 are likewise conceivable;

[0100] pneumatic devices which, when activated, exert the required force for moving the respective rotor 210, 310 or possibly stator 220, 320, may for example be provided.

[0101] In order to ensure safety, an electrical machine has to be able to be switched off safely, including when the rotor continues to be rotated by external influences. In order to ensure reliability, however, a plurality of electrical machines have to be integrated into a mechanical chain, and all of the machines have to be able to be switched off safely, including when the rotor continues to be rotated by the remaining machines. This apparent conflict is solved by the approach proposed here.

[0102] The proposed solution accordingly makes it possible to efficiently use the redundancy of the electrical machine 10 even with a plurality of stator winding systems by preventing the undesired input of energy into a defective winding system by magnetically decoupling the associated rotor part, which leads to a reduction in the probability of occurrence of fire in the electrical machine.

[0103] For those embodiments and variants in which the machine is designed as a radial flux machine, it has been assumed merely by way of example that the rotor arrangement is equipped with internal rotors 210, 310. It should however be assumed that the same principle of movement in order to increase the respective air gap is also able to be implemented with electrical machines that operate with external rotors.