DE102024102179A1 - Electrical machine with a safety gear - Google Patents

Abstract

An electrical machine (1A-1E), in particular for an aircraft (2), comprises: a stator (10A-10E), a rotor (11A-11E) and a safety device (12A-12C), wherein the rotor (11A-11E) is rotatably mounted relative to the stator (10A-10E) such that a first contact area (K1) fixed to the rotor (11A-11E) is spaced from a second contact area (K2) fixed to the stator (10A-10E) during normal operation of the electrical machine (1A-1E), wherein the contact areas (K1, K2) can be contacted with one another as a result of a force acting on the rotor (11A-11E), and wherein the safety device (12A-12C) comprises at least one movable and/or abrasive element (120-124) which connects the first and/or the second contact area (K1, K2) trained.

Description

The present disclosure relates in particular to an electric machine, to an electric drive unit and to an aircraft.

Vehicles, especially aircraft, are powered in a wide variety of ways. Internal combustion engines, such as piston engines or gas turbine engines, enable long ranges and high speeds. Electric drive units with an electric motor, in contrast, enable the use of sustainably generated energy and are sometimes particularly low-maintenance and quiet. Advances in battery and fuel cell technology are opening up ever-expanding areas of application for electric drive units.

In various applications, such as electrically powered aircraft, large forces can act on the propeller of an electric propulsion unit in various situations, for example, in the event of a strong crosswind or in accident situations such as a bird strike. Such events can result in damage.

The object of the present invention is to increase the safety of an electrical machine.

According to one aspect, an electric machine, in particular for an aircraft, is specified. The electric machine comprises a stator, a rotor, and a safety catch. Provision is made for the rotor to be rotatably mounted relative to the stator such that a first contact region fixed to the rotor is spaced apart from a second contact region fixed to the stator during normal operation of the electric machine. The contact regions can be touched by means of a force acting on the rotor. The safety catch comprises at least one movable and/or abrasive element forming the first and/or second contact region.

In this way, many unforeseen movements of the rotor that could lead to contact between the rotor and the stator can be intercepted without damaging the electrical machine in a short period of time or even in a single event. Rather, it is possible to tolerate contact over a certain period of time, thereby maintaining the functionality of the electrical machine and preventing subsequent damage. This can increase the safety of an electrical machine. Furthermore, in many cases, repairs can be carried out without having to replace the entire electrical machine.

The at least one movable element is mounted on the stator for movement (e.g., rotation or displacement), in particular, is held movably on the stator and/or such that a movement of the rotor relative to the stator can cause the movable element to move (e.g., rotate). This allows the rotor to be securely supported, making it possible to prevent damage, e.g., due to grinding of rotor material on the stator.

For example, at least one movable element is mounted on the stator so that it can rotate about a predetermined axis of rotation. This allows a defined movement to be specified, so that even unforeseen forces can be absorbed in a controlled manner.

The rotor is mounted so it can rotate relative to the stator about a rotor axis. The rotational axis of (at least one) movable element is aligned perpendicular to the rotor axis. This allows axial shocks to the rotor to be safely absorbed.

The (at least one) movable element is designed, for example, in the form of a (cylindrical or conical) roller or a ball. This allows the rotor to be guided smoothly and smoothly.

The abrasive element (or one of several abrasive elements) of the safety gear is designed, for example, in the form of an abrasive layer and/or fixed to a stator support. If the rotor slides along the abrasive layer due to an unforeseen force or similar, kinetic energy can be dissipated through abrasion of the material.

In some embodiments, the abrasive element is a first abrasive element, and the safety device comprises a second abrasive element. The second abrasive element, for example, has a greater hardness and/or strength than the first abrasive element. This allows the rotor to be safely secured in various events or damage scenarios.

The first abrasive element is, for example, designed in the form of an abrasive layer that covers the second abrasive element. This allows the rotor to be caught by the first abrasive element without causing damage, e.g., in the case of a single event. However, if there is, for example, a persistent If damage occurs that leads to the complete abrasion of the first abrasive layer at one point, the second abrasive layer can prevent subsequent damage from occurring.

For example, the first abrasive element comprises or consists of a metal oxide and/or a silicate. Alternatively or additionally, the second abrasive element can comprise a ceramic. This can achieve particularly good braking and protective properties.

In some embodiments, the first abrasive element is arranged closer to the first contact area than the at least one movable element. Alternatively or additionally, for example, the at least one movable element is arranged closer to the first contact area than the second abrasive element. This allows for a sequential contacting and thus a step-by-step interception of the rotor in the event of a fault.

The first contact area may have a layer of paint. The paint layer, for example, presents a strong color contrast with the substrate. For example, the substrate may be silver or gray (e.g., steel) and the paint layer may be a color such as blue, red, green, or yellow (or a blend of two or more of these colors). A layer of paint makes it easy and particularly reliable to determine during an inspection whether contact has been made between the contact areas, as grinding marks in the paint layer are easily visible. This allows, for example, slow-developing damage to be detected early and easily.

A viewing window can be provided on the stator and/or rotor. The viewing window allows the paint layer (at least part of it) to be visible. This can significantly facilitate inspection, as it eliminates the need to remove the rotor.

Permanent magnets, for example, are fixed to the rotor, and electrical coils are fixed to the stator. The electrical machine is a permanent-magnet synchronous machine, for example. Such machines enable particularly high power outputs.

For example, the first and/or second contact areas each extend along the shape of a circular disk and/or are arranged according to the shape of a circular disk. This enables secure axial support.

The first and/or second contact areas can also each extend along the shape of a circular cylinder and/or be arranged according to the shape of a circular cylinder. This enables reliable radial interception.

According to one aspect, an electrical machine is specified, in particular according to any of the embodiments described herein, comprising: a stator with at least one coil, a rotor with at least one permanent magnet spaced from the stator by a gap, and a safety catch. The rotor is rotatably mounted relative to the stator such that a first contact region fixed to the rotor is spaced from a second contact region fixed to the stator by a distance during normal operation of the electrical machine, wherein the contact regions can be contacted with one another as a result of a force acting on the rotor, and wherein the distance between the first and second contact regions is smaller than the gap.

According to one aspect, an electric drive unit is provided, comprising the electric machine according to any of the embodiments described herein. The electric drive unit may further comprise a propeller driven by the electric machine. Regarding the advantages, reference is made to the above information.

According to one aspect, a vehicle, in particular an aircraft, is provided, comprising the electric machine and/or the electric drive unit according to any of the embodiments described herein. The advantages of the electric machine and the electric drive unit described herein are particularly evident in a vehicle, in particular in an aircraft.

• 1 ein Luftfahrzeug in Form eines Flächenflugzeugs mit zwei elektrischen Antriebseinheiten;
• 2 eine Schnittansicht einer der elektrischen Antriebseinheiten des Luftfahrzeugs gemäß 1;
• 3 eine Ansicht eines Teils der elektrischen Antriebseinheit gemäß 2;
• 4 eine Schnittansicht einer elektrischen Antriebseinheit für das Luftfahrzeug gemäß 1;
• 5 und 6 Schnittansichten einer elektrischen Maschine für eine der elektrischen Antriebseinheiten des Luftfahrzeugs gemäß 1;
• 7 eine Schnittansicht einer elektrischen Maschine für eine der elektrischen Antriebseinheiten des Luftfahrzeugs gemäß 1 in Form eines Außenläufers; und
• 8 eine Schnittansicht einer elektrischen Maschine für eine der elektrischen Antriebseinheiten des Luftfahrzeugs gemäß 1 in Form eines Scheibenläufers.

Embodiments will now be described by way of example with reference to the figures; in the figures, in a schematic representation:

• 1 an aircraft in the form of a fixed-wing aircraft with two electric propulsion units;
• 2 a sectional view of one of the electric drive units of the aircraft according to 1 ;
• 3 a view of a part of the electric drive unit according to 2 ;
• 4 a sectional view of an electric drive unit for the aircraft according to 1 ;
• 5 and 6 Sectional views of an electric machine for one of the electric drive units of the aircraft according to 1 ;
• 7 a sectional view of an electric machine for one of the electric drive units of the aircraft according to 1 in the form of an external rotor; and
• 8 a sectional view of an electric machine for one of the electric drive units of the aircraft according to 1 in the form of a disc rotor.

1 shows an aircraft 2 in the form of an electrically powered aircraft with a fuselage 20 and wings 21.

The aircraft 2 comprises at least one electric drive unit 3, here several, specifically two, electric drive units 3. Each of the electric drive units 3 comprises an electric motor, described in more detail below, and a propeller 30. The driven propellers 30 generate thrust for the aircraft 2. In the present case, one electric drive unit 3 is mounted on each of the wings 21 of the aircraft 2, although other arrangements would also be conceivable. The propellers 30 comprise several, here, for example, three propeller blades 300, which are mounted on a hub.

In alternative embodiments, the aircraft 2 comprises, for example, a fan instead of a propeller and/or one or more electric drive units, each with at least one propeller, fan, or other rotor unit. The aircraft 2 receives lift primarily from air flowing over the wings 21, although it would also be conceivable to provide pivoting or additional propellers for this purpose.

Furthermore, the aircraft 2 comprises, by way of example, a battery system 22 (or alternatively or additionally, another energy source, e.g., a fuel cell, a generator, a photovoltaic system, or the like). The battery system 22 stores electrical energy for operating the electric drive units 3. The battery system 22 comprises a plurality of rechargeable battery cells. The battery system 22 is connected to inverters, which convert a direct voltage of the battery system 22 into an alternating voltage. The alternating voltage is applied to the electric machine of the respective electric drive unit 3 in order to set the respective propeller 30 in rotation and thus drive the aircraft 2.

2 shows a simplified representation of the electric machine 1A of one of the electric drive units 3 of the aircraft 2.

The electrical machine 1A is designed here as an example in the form of a permanent magnet synchronous machine. 2 It can be seen that the electrical machine 1A is designed as an internal rotor, although it is of course also possible to design it as an external rotor or disc rotor.

The electric machine 1A comprises a stator 10A and a rotor 11A rotatable relative thereto. The stator 10A has a receptacle (not designated) in which the rotor 11A is rotatably mounted.

The stator 10A comprises a body, here in the form of a laminated core, to which teeth are fixed, which can also be referred to as stator teeth. The stator 10A has one or more winding systems, which can also be referred to as phases or “lanes”. The or each winding system has windings for three electrical phases U, V, W. Electrical conductors of the winding system or systems are wound in the form of coils around the teeth of the stator 10A. The or each winding system is designed for multi-phase, here three-phase, operation and is connected to the three-phase alternating voltage with the phases U, V, W. During normal operation of the electrical machine 1A, the winding system or systems are supplied with the alternating voltage.

The rotor 11A comprises permanent magnets to provide the magnetic flux. The rotor 11A is mounted for rotation about a rotor axis R relative to the stator 10A. For this purpose, the rotor 11A is mounted for rotation on bearings, e.g., on the stator 10A. During normal operation, the three-phase alternating voltage, whose phases U, V, and W are each phase-shifted by 120°, generates a rotating magnetic field. This rotating field interacts with the permanently excited magnetic field provided by the rotor 11A, so that, during motor operation, a corresponding rotational movement of the rotor 11A relative to the stator 10A can be induced. In the present case, it is provided that the electric machine 1A serves as the drive motor for the propeller 30. During operation, the electric motor 10 is supplied with, for example, 100 kW up to 10 MW. It can also be provided that the electric machine 1A can be operated in generator mode.

The electrical machine 1A further comprises a safety gear 12A.

It is provided that the rotor 11A is rotatably mounted relative to the stator 10A (e.g. on the stator 10A) in such a way that a first contact area K1 fixed on the rotor 11A is contacted by a second contact area K2 fixed on the stator 10A during normal operation of the electrical machine 1A is spaced apart, wherein the contact areas K1 can be contacted with one another as a result of a force acting on the rotor 11A.

Generally speaking, the safety device 12A comprises at least one movable element and/or at least one abrasive element or friction element or abrasion element, which forms/forms the first and/or the second contact area K1, K2.

In the example according to 2 the safety device 12A comprises a plurality of movable elements 120 and a plurality of abrasive elements 123, 124 or friction elements or abrasion elements.

A gap, here an air gap L, is formed between the first contact area K and the second contact area K2.

2 shows a view of the electric drive unit 3, which is cut along a plane in which the rotor axis R runs.

3 shows a view of the electric drive unit 3, which is cut along a plane that is perpendicular to the rotor axis R and that passes through the air gap L. 3 shows a part of the stator 10A.

As shown by 2 The contact areas K1, K2 are clearly spaced apart from one another at every point. The contact areas K1, K2 are spaced apart from one another in the axial direction parallel to the rotor axis R. The contact areas K1, K2 do not touch one another during normal operation. If the rotor 11A rotates about the rotor axis R relative to the stator 10A, the contact areas K1, K2 always remain spaced apart from one another over a complete rotation of the rotor 11A. Even over an entire flight of the aircraft 2 (including takeoff, flight phase, and landing), the contact areas K1, K2 do not touch one another, and are therefore always spaced apart from one another. By means of a bearing device, the rotor 11A is therefore rotatably mounted relative to the stator 10A in such a way that the first contact area K1 of the rotor 11A is spaced apart from the second contact area K2 of the stator 10A during normal operation of the electric machine 1A.

In the event of a fault, elastic or plastic deformation of one or more components of the electric machine 1A may occur. This may be caused, for example, by damage to the bearing of the rotor 11A, a shaft connecting the rotor 11A to the propeller 30, or another part. Furthermore, a strong gust outside the design limits or a hard impact during landing outside the design limits may lead to such a fault.

In such a case, the first contact area K1 can come into contact with the second contact area K2. Because the electric machine 1A includes the safety gear 12A, such contact can be intercepted without causing subsequent damage. The rotation of the rotor 11A can thus be slowed down without the need for electrical braking.

The safety device 12A comprises a first abrasive element 123 in the form of an abrasive layer, which forms the second contact area K2. As can be seen in the overview of the 2 and 3 As can be seen, the safety device 12A comprises a plurality of, here three, first abrasive elements 123, which form the second contact area K2. Surfaces of the first abrasive elements 123 run along sections of a common circular disk shape. The surfaces of the first abrasive elements 123 forming the second contact area K2 lie in one plane. The surface of each of the first abrasive elements 123 forming part of the second contact area K2 has the shape of an (isosceles) trapezoid (alternatively, for example, the shape of part of a circular disk). The plurality of, here three, first abrasive elements 123 are arranged equidistant from one another around the rotor axis R.

The second abrasive element 124 is arranged below each first abrasive element 123. The first abrasive elements 123 thus cover the respective second abrasive elements 124. The first abrasive elements 123 are each arranged between the respective second abrasive element 124 and the first contact area K1. The second abrasive elements 124 are each designed in the form of an abrasive layer. The second abrasive elements 124 are each fastened to a respective carrier 100 of the stator 10A. The first abrasive elements 123 are fastened to the respective second abrasive element 124. The first abrasive elements 123 are fastened to the respective carrier 100 by the respective second abrasive elements 124.

The second abrasive elements 124 here, for example, have a greater hardness than the first abrasive elements 123, e.g. according to Mohs and/or Rockwell (e.g. HRC).

The second abrasive elements 124 here also have, for example, a greater strength (e.g., compressive and/or shear strength) than the first abrasive elements 123.

The abrasive elements 123, 124 each form a brake pad and, together with the carrier 100, a brake block.

The first abrasive elements 123 each comprise, for example, a metal oxide and/or a silicate. The first abrasive elements 123 may comprise a friction agent and a binder. The first abrasive elements 123 may comprise a powder held by a binder.

The second abrasive elements 124 here comprise, for example, a ceramic.

The abrasive elements 123, 124 can be screwed on, glued on, or painted on and cured.

The safety gear 12A comprises, in the present example, three movable elements 120. The movable elements 120 of the safety gear 12A are each designed in the form of a roller (each with a circular cylindrical shape). Alternatively, the movable elements 120 can also be conical or spherical. Each of the movable elements 120 is mounted on the stator 10A, more precisely on the respective support 100 of the stator 10A, for rotation about a rotation axis D. The supports 100 are fastened to an end face of the stator 10A (or formed thereon or thereby). The rotation axes D are each aligned perpendicular to the rotor axis R. The rotation axes point toward each other in a star shape. Straight lines passing through the rotation axes D intersect each other at the rotor axis R.

The movable elements 120 are therefore mounted on the stator 10A in a movable, namely rotatable, manner.

Viewed along a circle around the rotor axis R, the movable elements 120 and the abrasive elements 123, 124 alternate. Between each two movable elements 120, at least one abrasive element 123, 124, here a first and a second abrasive element 123, 124, is arranged. Between each two spaced-apart abrasive elements 123, 124, a movable element 120 is arranged.

As can be seen in particular from 2 As can be seen, the first abrasive elements 123 are arranged closer to the first contact area K1 in a direction parallel to the rotor axis R than the movable elements 120. The movable elements 120 are in turn arranged closer to the first contact area K1 than the second abrasive elements 124 (viewed in the same direction). If contact occurs between the contact areas K1, K2, this contact is initially only established between the first contact area K1 and the first abrasive elements 123. If the rotor 11A grinds along the first abrasive elements 123 with the first contact area K1 for a time, these are thereby removed until the first contact area K1 at least partially rests against the movable elements 120 and rolls against it. The movable elements 120 then at least partially form the surface of the second contact area K2. If the movable elements 120 also become worn or otherwise damaged, the first contact area K1 comes into at least partial contact with the second abrasive elements 124, which then at least partially form the surface of the second contact area K2. The second abrasive elements 124 can withstand the impact of the rotor 11A for longer than the first abrasive elements 123.

The first contact area K1 further comprises a colored layer 125. The colored layer 125 is presently in the form of a varnish. The colored layer 125 is applied to a base 110 of the rotor 11A. The colored layer 125 has a (clearly visible) brightness and/or color difference compared to the surface of the base 110. For example, the colored layer 125 has a blue, green, red, or yellow color, or a mixture of, for example, two (or more) of these colors. The surface of the base 110 covered by the colored layer 125 has, for example, a gray or silver color. If the first contact area K1 has ground the second contact area, this is easily recognizable by grinding marks or completely removed areas of the colored layer 125.

As shown by the 2 and 3 As can be seen, a viewing window 13A is formed on the stator 10A, through which the color layer 125 is visible, as in 2 illustrated by an arrow.

The viewing window 13A is arranged between a movable element 120 and a pair of first and second abrasive elements 123, 124. The viewing window 13A is arranged in this case to allow a view of the paint layer 125 in a viewing direction parallel to the rotor axis R. The viewing window 13A has an opening in an end face of the stator 10A, to which the supports 100 are also attached. The opening can be closed with a transparent component, e.g., made of glass. This allows the condition to be quickly and easily visually inspected, for example, before takeoff.

According to 2 and 3 the first and second contact areas K1, K2 each run along the shape of a circular disk.

The air gap between the contact areas K1, K2 is in this case smaller than a gap between permanent magnets of the rotor 11A and coils of the stator 10A, so that they do not come into contact with each other even if the contact areas K1, K2 touch.

The safety device 12A thus serves as passive protection against structural damage and for the identification of faults. Sensors or similar devices are not necessary, but can be additionally provided to detect contact between the contact areas K1, K2 (particularly simple sensors may be sufficient here). For example, the abrasive elements and/or the movable elements are electrically conductive, and contact closes an electrical circuit, which is recorded by a measuring device.

4 illustrates an electric drive unit with an electric machine 1B for the aircraft 2. The electric machine 1B in turn comprises a stator 10B, a rotor 11B and a safety device 12B, wherein the rotor 11B is rotatably mounted relative to the stator 10B such that a first contact region K1 fixedly provided on the rotor 11B is spaced from a second contact region K2 fixedly provided on the stator 10B during normal operation of the electric machine 1B, wherein the contact regions K1, K2 can be brought into contact with one another as a result of a force acting on the rotor 11B, and wherein the safety device 12B comprises at least movable and abrasive elements 121-124 which form the first and second contact regions K1, K2.

Here, the rotor 11B has a base 110, which describes an annular surface which forms part of the first contact area K1.

In the present case, the contact regions K1, K2 each have a part on axially spaced-apart sections of the rotor 11B and the stator 10B. In the example shown, the parts of the first contact region K1 are arranged at the two axial ends of the rotor 11B, and the parts of the second contact region K2 are aligned with the parts of the first contact region K1 and, in this case, encompass them.

Part of the contact areas K1, K2, in 4 shown on the right, is constructed similarly to that described above, with several units (which serve as brake pads) each comprising a first abrasive element 123 and a second abrasive element 124. Three or more of these units can be arranged distributed around the rotor axis R.

The first contact area K1 runs along the outer side of the circular cylinder. The second contact area K2 runs along the inner side of the circular cylinder. A circular-cylindrical air gap L is formed between the contact areas K1 and K2.

The first contact area K1 is again formed by a color layer 125.

A viewing window 13B allows a view in the radial direction onto the paint layer 125. The viewing window 13B is arranged, for example, between two units of abrasive elements 123, 124.

The movable elements 121 are each designed, for example, in the form of ball bearings and each comprise an inner ring, which is fastened to a pin of the stator 10B, a ring of balls, and an outer ring, which each form a part of the second contact area K2. For example, three or more such ball bearings are provided. If the rotor 11B is moved in the radial direction from its position during normal operation, the rotor 11B can be moved with the front, in 4 The part of the first contact area K1 shown on the left can abut against one or more of the movable elements 121 and cause them to move. The ball bearings of the movable elements 121 are smaller and lighter than a large ball bearing extending around the rotor axis R would be.

It is therefore clear that the movable elements 121 can be arranged at a distance from the abrasive elements 123, 124, e.g. as in 4 along the rotor axis R.

As already mentioned, the stator 10B comprises at least one coil, and the rotor 11B comprises permanent magnets that are spaced apart from the stator 10B by a gap S. The rotor 11B is rotatably mounted relative to the stator 10B such that the first contact area K1 fixed to the rotor 11B is spaced apart from the second contact area K2 fixed to the stator 10B by a distance (the air gap L) during normal operation of the electric machine 1B. The contact areas K1, K2 can be contacted with one another as a result of a force acting on the rotor 11B, and the distance between the first and second contact areas K1, K2 is smaller than the gap S. The contact areas K1, K2 are arranged such that, when the rotor 11B moves relative to the stator 10B, they come into contact with one another before other parts of the rotor 11B and the stator 10B come into contact with one another, in particular before the gap is closed (see also, for example, 2 ).

5 and 6 show a further electric machine 1C for the aircraft 2, wherein the 6 shown excerpt in 5 The rotor 11C is shown at the moment of a fault occurring. As a result of an external force, the rotor 11C is distorted (highly exaggerated) and an edge of the rotor 11C is about to make contact with a part of the first area K1 to contact the second contact area K2 (in 5 highlighted).

In this case, the safety device 12C according to 5 and 6 a first abrasive element 123 and a second abrasive element 124 on the stator 10C (on an inner surface thereof), and another abrasive element 126 on the rotor 11C (on an outer surface thereof).

Movable elements 122 are provided in the first abrasive element 123 (and second abrasive element 124). The movable elements 122 are designed as rollers aligned parallel to the rotor axis R.

The first abrasive element 123 is arranged in the form of a sleeve within the second abrasive element 124. The second abrasive element 124 is also designed in the form of a sleeve and is arranged in the stator 10C. The abrasive element 126 of the rotor 11C is designed in the form of a sleeve that surrounds the rotor 11C.

In the axial direction, several movable elements 122, here two, are arranged one behind the other. Several movable elements 122 are arranged distributed around the rotor axis R.

7 shows a further possible embodiment of an electric machine 1D of one of the electric drive units 3 of the aircraft 2. The electric machine 1D is designed in the form of an electric motor (which can optionally also be used as a generator) and comprises a stator 10D, a rotor 11D, a bearing 14 and a shaft 15.

The rotor 11D is rotatably mounted relative to the stator 10D about a rotor axis R by means of the bearing 14. The electric machine 1D is designed as an external rotor. Thus, the rotor 11D surrounds the stator 10D. The stator 10D is at least partially accommodated in the rotor 11D. The stator 10D is rigidly mounted on a support of the aircraft 2. For example, the stator is fixed relative to the fuselage 20.

The bearing 14 is designed here, for example, in the form of a ball bearing.

The rotor 11D is operatively connected, e.g., firmly connected, to the propeller 30 via the shaft 15.

The stator 10D comprises a base 102 to which several electrical coils 101 are attached. The rotor 11D comprises a base 110 to which several magnets, here in the form of permanent magnets 111, are attached. Permanent-magnet electrical machines allow for particularly high power and torque densities.

An electric current through the coils 101 generates a magnetic field that causes the rotor 11D to rotate about the rotor axis R. An (air) gap L is formed between the stator 10D and the rotor 11D, across which the magnetic forces between the stator 10D and the rotor 11D act. The air gap L is generally filled with a gas or gas mixture, in this case, air. The air gap L has a circular cylindrical shape. Thus, the rotor 11D and the stator 11D are separated from each other by a hollow cylindrical gap.

The electrical machine 1D comprises a safety gear 12A-12C according to 2 and 3 , according to 4 and/or according to 5 and 6 .

8 shows an electric machine 1E for the aircraft 2, which the aircraft 2 uses instead of the electric machine 1A according to 2 , or in addition to it.

The electric machine 1E comprises a stator 10E and a rotor 11E rotatable relative to the stator 10E, wherein a circular disk-shaped gap, here an air gap L, is formed between the rotor 11E and the stator 10E, across which circular disk-shaped gap magnetic forces act between the stator 10E and the rotor 11E. Furthermore, the electric machine 1E comprises a bearing device with bearings 14, by means of which the rotor 11E is rotatably mounted relative to the stator 10E such that a first contact region K1 of the rotor 11E is spaced from a second contact region K2 of the stator 10E during normal operation of the electric machine 1E.

The electric machine 1E is an axial force machine (alternatively, a transverse force machine, for example), i.e., the magnetic fields bridge the air gap L in the axial (transverse) direction. The contact areas K1, K2 of the rotor 11E and the stator 10E are spaced apart from each other in the axial direction, parallel to the rotor axis R.

The electrical machine 1E comprises a safety gear 12A-12C according to 2 and 3 , according to 4 and/or according to 5 and 6 .

The electrical machines 1A-1E were primarily described with reference to the aircraft 2. However, it should be noted that such an electrical machine 1A-1E with a safety gear 12A-12C can also be used elsewhere, for example, in a motor vehicle, such as an electric car, instead of for an aircraft. Instead of a propeller, one or more several wheels are driven by the electric machine 1A-1E.

The abrasive elements 123, 124, 126 and the movable elements 120, 121, 122 can be interchangeable, e.g. after a light touch.

It should be understood that the invention is not limited to the embodiments described above, and various modifications and improvements may be made without departing from the concepts described herein. Any of the features may be used separately or in combination with any other features, provided they are not mutually exclusive, and the disclosure extends to and encompasses all combinations and subcombinations of one or more of the features described herein.

List of reference symbols

1A-1E

electric machine

10A-10E

stator

100

carrier

101

Sink

102

base

11A-11E

rotor

110

base

111

permanent magnet

12A-12C

Safety gear

120

movable element

121

movable element

122

movable element

123

first abrasive element

124

second abrasive element

125

Paint layer

126

abrasive element

13A, 13B

Viewing window

14

warehouse

15

Wave

2

aircraft

20

hull

21

wing

22

Battery system

3

electric drive unit

30

propeller

300

propeller blade

D

axis of rotation

K1, K2

Contact area

L

air gap

R

Rotor axis

S

gap

Claims (18)

An electric machine (1A-1E), in particular for an aircraft (2), comprising: - a stator (10A-10E), - a rotor (11A-11E), and - a safety device (12A-12C), wherein the rotor (11A-11E) is rotatably mounted relative to the stator (10A-10E) such that a first contact region (K1) fixed to the rotor (11A-11E) is spaced from a second contact region (K2) fixed to the stator (10A-10E) during normal operation of the electric machine (1A-1E), wherein the contact regions (K1, K2) can be contacted with one another as a result of a force acting on the rotor (11A-11E), and wherein the safety device (12A-12C) comprises at least one movable and/or abrasive element (120-124) which connects the first and/or the second contact region (K1, K2) is trained. Electrical machine (1A-1E) according to Claim 1 , wherein the at least one movable element (120-122) is movably mounted on the stator (10A-10E). Electrical machine (1A-1E) according to Claim 2 , wherein the at least one movable element (120-122) is mounted on the stator (10A-10E) so as to be rotatable about a fixed axis of rotation (D). Electrical machine (1A) according to Claim 3 , wherein the rotor (11A) is rotatably mounted about a rotor axis (R) relative to the stator (10A) and the axis of rotation (D) is aligned perpendicular to the rotor axis (R). Electrical machine (1A-1E) according to one of the Claims 2 until 4 , wherein the at least one movable element (120-122) comprises a roller or a ball. Electrical machine (1A-1E) according to one of the preceding claims, wherein an abrasive element (123, 124) of the safety device (12A-12C) is fixed in the form of an abrasive layer on a carrier (100) of the stator (10A-10E). Electrical machine (1A-1E) according to Claim 6 , wherein the abrasive element (123) is a first abrasive element and the catching device (12A-12C) is a second abrasive element (124) which has a greater hardness and/or strength than the first abrasive element (123). Electrical machine (1A-1E) according to Claim 7 , wherein the first abrasive element (123) is in the form of an abrasive layer which covers the second abrasive element (124). Electrical machine (1A-1E) according to Claim 7 or 8 , wherein the first abrasive element (123) comprises a metal oxide and/or a silicate and the second abrasive element (124) comprises a ceramic. Electrical machine (1A, 1B) according to one of the Claims 2 until 5 and after one of the Claims 7 until 9 , wherein the first abrasive element (123) is arranged closer to the first contact area (K1) than the at least one movable element (120, 121) and wherein the at least one movable element (120, 121) is arranged closer to the first contact area (K1) than the second abrasive element (124). Electrical machine (1A-1E) according to one of the preceding claims, wherein the first contact region (K1) has a color layer (125). Electrical machine (1A, 1B) according to Claim 11 , wherein a viewing window (13A, 13B) is formed on the stator (10A, 10B) and/or on the rotor (11A, 11B), through which the color layer (125) is visible. Electrical machine (1A-1E) according to one of the preceding claims, wherein permanent magnets (111) are fixed to the rotor (11A-11E) and electrical coils (101) are fixed to the stator (10A-10E). Electrical machine (1A, 1E) according to one of the preceding claims, wherein the first and/or the second contact region (K1, K2) each extend along the shape of a circular disk. Electrical machine (1B-1D) according to one of the Claims 1 until 13 , wherein the first and/or the second contact region (K1, K2) each extend along the shape of a circular cylinder. Electrical machine (1A-1E), in particular according to one of the preceding claims, comprising: - a stator (10A-10E) with at least one coil (101), - a rotor (11A-11E) with at least one permanent magnet (111) which is spaced from the stator (10A-10E) by a gap (S), and - a safety device (12A-12C), wherein the rotor (11A-11E) is rotatably mounted relative to the stator (10A-10E) such that a first contact area (K1) fixed to the rotor (11A-11E) is spaced from a second contact area (K2) fixed to the stator (10A-10E) by a distance during normal operation of the electrical machine (1A-1E), wherein the contact areas (K1, K2) can be contacted with one another as a result of a force acting on the rotor (11A-11E), and wherein the distance between the first and the second contact area (K1, K2) is smaller than the gap (S). Electric drive unit (3) for an aircraft (2), comprising the electric machine (1A-1E) according to one of the preceding claims and a propeller (30) driven by the electric machine (1A-1E). Aircraft (2), comprising the electric machine (1A-1E) according to one of the Claims 1 until 16 and/or the electric drive unit (3) according to Claim 17 .