Aircraft propulsion system with electric machine with printed material layers

Abstract

The invention relates to an electric machine for an electric aircraft propulsion system for an aircraft, in particular an unmanned aircraft, which can be in the form of a drone or multicopter, for example. In particular, the invention relates to the design of the active parts of the electric machine, which are formed as material layer stacks with a plurality of material layers. Some of the material layers are characterised in that they are in the form of printed, e.g. screen / stencil-printed, layers, wherein the material layer stack for the electric machine of the aircraft propulsion system is composed of alternately arranged printed layers and insulation layers.

Description

[0001]202208785 1 Description Aircraft propulsion system with electric machine with printed material layers Regardless of the grammatical gender of a particular term, persons with male, female, or other gender identities are included. The invention relates to an electric machine for an electric propulsion system of an aircraft, in particular an unmanned aircraft, which can be designed, for example, as a drone. In particular, the invention relates to the design of the active parts of the electric machine. For propulsion of aircraft, e.g., airplanes or helicopters, concepts based on electric propulsion systems are being investigated and used as an alternative to conventional internal combustion engines.Such an electric drive system, which can be designed as a purely electric or as a hybrid-electric drive system, generally has one or more electrical machines that can be configured as a generator and / or as an electric motor depending on the intended use in the drive system. Such electric drive systems are of particular interest for unmanned aerial vehicles. These can be designed, for example, as aircraft with corresponding wings or as rotary-wing aircraft, e.g. as multicopters. Such aircraft are often referred to as "drones". They are used in both the civil and military sectors, with the tasks in civil and commercial use lying, for example, in the area of ​​logistics or customer service, e.g. in the inspection of power lines or similar. In the military sector, drones are used in particular for reconnaissance.202208785 2 When using such electric propulsion systems for aircraft, weight and efficiency are crucial to ensure a sufficiently long range. Furthermore, especially in rotary-wing aircraft, which constantly readjust the speeds of the propellers used to control their flight stability, torques must be changed quickly and adapted to current flight situations. Common electric machines in this environment have disadvantages with regard to their efficiency and weight, which adversely affects the range of the aircraft equipped with them. It is therefore an object of the present invention to introduce an approach that allows the operation of an electric aircraft without the aforementioned disadvantages.This is achieved by the electric aircraft propulsion system described in claim 1, its use according to claim 9, the manufacturing method according to claim 10 and the operating method according to claim 11. The respective subclaims describe advantageous embodiments. An electric aircraft propulsion system for an aircraft comprises at least one machine group with at least one electrical machine designed as an electric motor or as a generator. Each electrical machine in this machine group has an active part with a material layer stack MS as a laminated core, wherein the respective material layer stack MS comprises a plurality of material layers printed using a printing process, in particular a material transfer printing process, preferably a screen, stencil and / or roller printing process.In the minimal embodiment, the aircraft propulsion system is defined as comprising only the aforementioned electrical machine with printed material layers. However, it may include other components such as, for example, other such electrical machines, energy storage devices, combustion engines, etc., wherein any existing electrical machines may be configured as electric motors or generators as needed. The term "electric aircraft propulsion system" is intended to encompass both a hybrid-electric and a purely electric propulsion system. The active part of a respective electrical machine of the machine group can be a stator and / or a rotor or at least a part of the stator or the rotor of the respective electrical machine, i.e., the stator and / or the rotor or at least parts thereof, e.g., stator teeth, can be constructed from the printed material layers.The fact that the stator and / or rotor, in particular, are constructed from the aforementioned stack of material layers ensures that the electrical properties of the machine are so pronounced that the aircraft can be driven efficiently and over long ranges. Furthermore, the use of an electric drive promises significantly reduced noise pollution compared to conventional combustion engine-based aircraft drives, thus meeting noise protection requirements, for example, even when the aircraft is used in a populated area.The plurality of material layers of the material layer stack MS can have flat, conductive layers made of electrically and / or magnetically conductive material as well as flat insulation layers made of electrically insulating material, wherein the plurality of these flat material layers of the material layer stack MS are stacked on top of one another in the axial direction such that at least one insulation layer lies between each two conductive layers. This type of structure brings about, among other things, a reduction in eddy current losses. Preferably, the conductive layers of the material layer stack represent the printed material layers. The insulation layers can be manufactured in a different way. 202208785 4 In particular, the conductive layers consist of a soft magnetic material, in particular iron, which in turn allows the properties of the electrical machine to be optimized with regard to performance and efficiency.With such a material layer stack, sheet thicknesses of the conductive layers on the order of approximately 100 µm are possible, which leads, for example, to strong eddy current suppression and a significant increase in efficiency. Furthermore, shorter and lighter electrical machines can be manufactured. The aircraft with the electric aircraft propulsion system can, for example, be an unmanned aerial vehicle, in particular a drone and, for example, a multicopter with a variety of propulsion devices, such as propellers.In this case, the machine group can comprise a first plurality of electrical machines corresponding to the number of drive means, each having an active part with a material layer stack MS as a laminated core, which is constructed from a plurality of screen-printed / stencil-printed material layers, wherein a respective electrical machine of the first plurality is designed as an electric motor for driving a respective drive means in one operating mode and is mechanically coupled to the respective drive means for this purpose. Depending on the design of the aircraft propulsion system, the machine group can further comprise a further number of electrical machines, which are configured and used, for example, as a generator in one operating mode. This is particularly advantageous if the electric aircraft propulsion system is to be designed as a hybrid-electric propulsion system for the aircraft.In this case, all electrical machines can be equipped with printed material layers as described, thus resulting in the advantages already mentioned. 202208785 5 In the case that the electric aircraft propulsion system is designed as a hybrid-electric propulsion system for driving a propulsion means, e.g., a propeller, of the aircraft, at least one of the electrical machines of the machine group is configured in an operating mode as an electric motor for driving the propulsion means and is or can be mechanically coupled to the propulsion means in order to drive it. Furthermore, in addition to the machine group with the specially designed, pressure-based electrical machines, the hybrid-electric aircraft propulsion system has an internal combustion engine.This combustion engine is integrated into the aircraft propulsion system in such a way that it is coupled or can be coupled to one of the electrical machines in the machine group, which in one operating mode is configured as a generator to provide electrical energy, in order to drive it so that it provides electrical energy. The combustion engine can also be coupled or can be coupled to the propulsion means of the aircraft in order to drive it. The term “propulsion means” can generally be understood as a collective term, i.e. the propulsion means can comprise several propellers or the like. In this case, for example, the electric motor can be coupled to a first propeller, while the combustion engine is possibly coupled to another propeller. Depending on the design of the hybrid-electric aircraft propulsion system, for example as a series hybrid or parallel hybrid system, various advantages arise, e.g.in terms of range and flexibility. With a purely electric system, the range is limited by the capacity of the required heavy energy storage device. The serial hybrid system promises an improvement here. The parallel hybrid system also has a positive effect in this regard. Both hybrid systems also allow the noisy combustion engine to be deactivated as needed, enabling quiet operation. Various designs of the hybrid-electric drive system are explained in more detail in the accompanying figures.The use of a material layer stack MS comprising a plurality of material layers printed using a printing process, in particular a screen, stencil or roll printing process, as a laminated core for at least one active part of at least one electrical machine of an electrical aircraft propulsion system of an aircraft as described above is therefore particularly advantageous. The production of such an electrical aircraft propulsion system, in which the machine group comprises at least one electrical machine, wherein this electrical machine has an active part with a material layer stack MS as a laminated core, wherein the material layer stack MS comprises a plurality of material layers orhas a plurality of flat conductive layers and flat insulating layers, provides for the conductive layers to be produced using a printing process, in particular a screen, stencil, or roller printing process, and for the conductive layers thus printed and the insulating layers to be applied to one another in the axial direction to produce the material layer stack MS in such a way that at least one insulating layer lies between two conductive layers of different material layers of the material layer stack MS. An operating method for an aircraft, e.g. an unmanned aircraft, in particular a drone, with such an electric aircraft propulsion system and with a propulsion group with at least one propulsion means, e.g. with one or more propellers, for generating propulsion for thefor driving the aircraft, wherein the machine group comprises a motor group with at least one electric motor, i.e. at least one of the electrical machines of the machine group operates in one operating mode as an electric motor, wherein each drive means 202208785 7 of the drive means group is driven by an electric motor of the motor group. The term “propulsion” should not be restricted to a single spatial direction, but should encompass the movement or acceleration of the aircraft in each of the three spatial directions. In addition to the engine group, the aircraft can have an internal combustion engine, wherein the operating method provides that at least one drive means of the drive means group is optionally driven by the internal combustion engine and / or by at least one of the electric motors of the motor group. This can be implemented in such a way that the internal combustion engine and electric motor are connected to different drive means orPropellers of the drive group act or that the combustion engine and electric motor are connectable to the same drive means or propeller, wherein, for example, one or the other motor is coupled to the drive means selectively using a coupling. In the event that the drive group comprises a plurality of drive means and the motor group a corresponding plurality of electric motors, wherein different electric motors are arranged and configured such that they drive different drive means, the operating method can provide for the different electric motors of the motor group to be controlled separately. This means that the respective output power, via which, for example, the speed of the propeller driven by the respective motor can be controlled, is set individually for each propeller.The special design of the electric motor with the material layer stack MS made of screen- / stencil-printed material layers allows for rapid corrections of flight attitudes, for example, in the case where the aircraft is a multicopter. The machine group can additionally have an electric machine designed as a generator. In this case, the 202208785 8 operating method provides that the combustion engine is used to drive the generator, and that the electrical energy thus provided by the generator is used to operate at least one electric motor of the motor group. Further advantages and embodiments emerge from the drawings and the corresponding description. The invention and exemplary embodiments are explained in more detail below with reference to drawings. There, the same components in different figures are identified by the same reference numerals.It is therefore possible that in the description of a second figure, no further explanation can be found for a specific reference symbol which has already been explained in connection with another, first figure. In such a case, it can be assumed in the embodiment of the second figure that the component identified there with this reference symbol has the same properties and functionalities as explained in connection with the first figure, even without further explanation in connection with the second figure. Furthermore, for the sake of clarity, not all reference symbols are shown in all figures, but only those to which reference is made in the description of the respective figure.8 shows a stack of material layers. It should be noted that terms such as “axial”, “radial”, “tangential” or “in the circumferential direction” etc. refer to the shaft or axis ROT used in the respective figure or in the respectively described example. In other words, the directions axial A, radial R, tangential U always refer to a rotational axis ROT of the rotor of the respectively described electrical machine.Here, “axial” describes a direction A parallel to the ROT axis of rotation, “radial” describes a direction R orthogonal to the ROT axis of rotation, towards it or away from it, and “tangential” is a movement or direction U orthogonal to the ROT axis and orthogonal to the radial direction R, which is therefore at a constant radial distance from the ROT axis of rotation and, at a constant axial position, in a circle around the ROT axis of rotation. The tangential direction U can also be referred to as the circumferential direction U. Furthermore, the terms “axial”, “radial” and “tangential” in connection with a surface, e.g. a surface, mean that the normal vector of the respective axial, radial or tangential surface is oriented in the axial, radial or tangential direction, whereby the orientation of the respective surface in space is uniquely described.The term "flat" means that the extension of a respective flat component in the axial direction, i.e., the layer thickness, is significantly smaller than the extension in the radial direction. For example, the radial extension of a flat component, i.e., the diameter, can be in the cm range, while its axial extension can be in the mm or even m range. The term "electromagnetic interaction" refers to the interaction known in an electrical machine between the magnetic fields of the magnetic means of the rotor, e.g., permanent magnets, and the magnetic means of the stator, e.g., current-carrying coils, due to which the electric motor develops its torque or due to which a generator supplies an electric current. FIGS. 1 and 2 show examples of a first and a second conceivable variant of an aircraft 1. This can be designed as an unmanned aircraft 1, e.g.as a drone with fragmentation surfaces in FIG. 1 and, for example, as a rotary-wing aircraft designed as a multicopter in FIG. 2. In both cases, the aircraft 1 is configured as an electric aircraft 1, i.e. the propulsion means 20 provided for generating the propulsion of the aircraft 1 are driven by an electric aircraft propulsion system 10, which comprises a suitable number of electric motors 100m and / or generators 100g. Depending on requirements, further components 100, 100g, 30, 40, 50 can be provided. The term “electric aircraft propulsion system” is intended to include both the design as a purely electric propulsion system and as a hybrid-electric propulsion system. The term “propulsion” is not intended to be limited to a single spatial direction, but rather to include the movement or acceleration of the aircraft 1 in each of the three spatial directions. In the following, it is assumed purely by way of example that thethe drive means 20 are designed as propellers. However, electrically driven turbines are also known, for example, which could also be used as drive means 20. Furthermore, it should be noted that only one propeller 20 is shown in FIGS. 3-6. Depending on the design of the aircraft 1, a larger number of propellers 20 can be provided. Accordingly, the one propeller 20 in FIGS. 3-6 is intended to represent such a possible plurality of propellers. FIGS. 3, 4, 5, 6 show various embodiments of the electric aircraft propulsion system 10. In all embodiments, the electric aircraft propulsion system 10 comprises at least one machine group with at least one 202208785 11 electric machine 100, which is operated as an electric motor 100m or as a generator 100g depending on the intended use.As will be explained in more detail in connection with FIG. 8, the electrical machines 100 of the machine group are characterized in that they have at least one active part, i.e. a rotor 110 and / or a stator 120 or at least parts thereof, with a material layer stack MS as a laminated core, which is constructed from a large number of printed, in particular screen-, stencil-, or roll-printed material layers. For example, the printed layers can be produced using a combination of a screen and a stencil printing process. In this exemplary case, they will be referred to below as “screen- / stencil-printed” if necessary. FIG. 3 shows an embodiment of the aircraft propulsion system 10 as a purely electrical system. The system 10 comprises the aforementioned electrical machine 100, which here is designed as an electric motor 100m.The electric motor 100m is connected to the propeller 20 in such a way that the latter can be driven by the motor 100m. The electrical energy eE required to operate the electric motor 100m is provided by an electrical energy storage device 40 of the aircraft propulsion system 10. FIGS. 4-6 show a first, second and third embodiment of the electric aircraft propulsion system 10 as a hybrid-electric system 10 for driving the propeller(s) 20 of the aircraft 1. These embodiments have in common that at least one of the electrical machines 100 of the machine group is set up in one operating mode as an electric motor 100m for driving the propeller 20 and is or can be mechanically coupled to the propeller 20 in order to drive it. Secondly, the aircraft propulsion system 10 has, in addition to the machine group with the specially designed, e.g.Screen / stencil printing-based electrical machines 100 have an internal combustion engine 30, 202208785 12 which, in the three embodiments to be explained below, is integrated into the aircraft propulsion system 10 in different ways. In the first embodiment of the aircraft propulsion system 10 as a hybrid-electric system 10 according to FIG. 4, at least one 100g of the electrical machines 100 of the machine group is operated in an operating mode as a generator 100g to provide electrical energy eE, which is to be used to supply the electric motor 100m, which in turn then drives the propeller 20. For this purpose, the generator 100g is coupled to the internal combustion engine 30, so that the internal combustion engine 30 can drive the generator 100g.The electrical energy eE provided by the generator 100g can be fed to an electrical energy storage device 40, which in turn provides the electrical energy eE required to operate the electric motor 100m. Additionally or alternatively, the electrical energy eE of the generator 100g can also be fed directly to the electric motor 100m. In any case, the electric motor 100m can drive the propeller 20 with the electrical energy eE supplied to it. The second embodiment of the aircraft propulsion system 10 as a hybrid-electric system according to FIG 5 is based on the first embodiment described above, ie the combustion engine 30 drives the generator 100g, which thus supplies the electrical energy eE to supply the electric motor 100m, either via the electrical energy storage 40 or directly, so that the electric motor 100m can drive the propeller 20.In addition, the combustion engine 30 is coupled or can be coupled to the propeller 20, for example, via a clutch 50. Depending on the desired operating mode of the aircraft 1, the propeller 20 can now be driven selectively by the combustion engine 30 and / or by the electric motor 100m, whereby the selective connection can be implemented, for example, by the appropriately configured clutch 50. In a variant of the second embodiment, 202208785 13 several propellers 20 can be provided, wherein one of the propellers 20 can then be driven by the electric motor 100m and the other by the combustion engine 30. Preferably, either the combustion engine 30 or the electric motor 100m is used to drive the aircraft 1, but not both simultaneously.In a third embodiment of the aircraft propulsion system as a hybrid-electric system according to FIG. 6, the internal combustion engine 30 and the electric motor 100m are coupled or can be coupled to the drive means, again for example via a coupling 50. Depending on the desired operating mode of the aircraft, the propeller 20 can thus be driven either by the internal combustion engine 30 and / or by the electric motor 100m. The generator 100g according to the first or second embodiment is not provided, i.e., the internal combustion engine 30 is possibly used only to drive the propeller 20. The electrical energy eE for the electric motor 100m is supplied by a precharged electrical energy storage device 40. In the case of a parallel hybrid propulsion system, as in the second and third embodiments, the combustion engine 30 is also detachably connected to the propeller 20 in order to drive it.In the case of the serial-hybrid drive system 10 of the first embodiment, the combustion engine 30 typically only drives the generator 100g, which in turn provides the electrical energy for the electric motor 100m and, if applicable, for an electrical energy storage device 40. In any case, the use of the material layer stack MS with printed material layers has an extremely positive impact on the fact that the optimization of the drive system 10 with regard to the interplay of reducible size, reducible weight, and maximized performance promises a significantly better result than for a drive system based on conventionally designed electric machines. This is particularly essential in the application of energy-intensive and simultaneously energy-sensitive aviation. The hybrid-electric system also allows switching from the combustion engine 30 to the purely electric drive 100m. For example,The combustion engine 30 can initially be used to propel the aircraft 1 over longer distances. Upon reaching a target region, for example in order to meet noise protection requirements, it is possible to switch to propulsion solely with the aid of the electric motor 100m, which promises minimal noise pollution. The machine groups of the electric aircraft propulsion systems 10 in the various embodiments shown in FIGS. 3-6 can each comprise a plurality of electric machines 100, and the drive means 20 can in turn also have a plurality of individual drive means, for example, several propellers 20 as shown in FIGS. 1, 2. If the aircraft 1 is designed, for example, as indicated in FIG. 2, as a multicopter with a plurality of propellers 20, the machine group can comprise a first number of electric motors 100m corresponding to the number of propellers 20.A respective electric motor 100m is designed to drive a respective propeller 20 and is mechanically coupled to the respective propeller 20 for this purpose. As already mentioned above and as explained below in connection with FIGS. 7-8, the electrical machines 100, 100m, 100g of the machine group are characterized in that they each have at least one active part 110, 120 with a material layer stack MS as a laminated core, which comprises a plurality of printed, for example screen / stencil printed, material layers 122 / i with i=1,...,N. FIG. 7 shows an electrical machine 100 designed as an electric motor 100m with a rotor 110 and a stator 120, as is known in the prior art. It should be mentioned that the electrical machine 100 in a comparable structure can in principle also be operated as a generator 100g.Furthermore, it should be noted that the structure of the machine 100 described below is greatly simplified and, moreover, does not show some of the details that may be explained in connection with the other figures, but merely serves to illustrate the basic mode of operation. Other peripheral devices that may be integrated during operation of the machine 100, such as a power source for providing a current to be fed into the stator windings 121 of the stator 120 (to be described later), as well as a component driven in this case via the rotor 110 or a consumer of a current induced in the stator windings 121, are not shown in FIG. 7 for the sake of clarity. It can be assumed that, depending on the design of the electrical machine 100, it can be designed as a generator or as an electric motor and / or, for example,as a radial or axial flux machine and / or with a rotor designed as an internal or external rotor, etc., the various components of the machine 100 can be arranged differently. In the merely exemplary illustration in FIG. 7, which is not representative in terms of scale or the number of components 111, 121, 122 in particular, the electric motor 100 has a substantially annular stator 120 and a substantially cylindrical rotor 110, designed as an internal rotor in the example shown here, wherein the rotor 110 is arranged within the stator 120 and rotates about a rotation axis ROT in the operating state of the electric motor 100. The rotor 110 or its essentially cylindrical rotor base body 112 is connected in a rotationally fixed manner to a shaft 130, so that a rotation of the rotor 110 via the shaft 130 is transmitted to a component to be driven, not shown in FIG. 7, for example.to one of the propellers 20 of the aircraft 1. The stator 120 has a plurality of first magnetic means 121, which can be implemented, for example, as stator windings 121 of a stator winding system of the electric machine 100. Each of the windings 121 is formed by a 202208785 16 electrical conductors. The conductors 121 are each wound on a stator tooth 122 of the stator 120 and, in the operating state of the electric motor 100, an electrical current flows through them, so that magnetic fields are generated. The teeth 122 and thus the stator windings 121 are arranged one behind the other along the circumferential direction U of the stator 120. The rotor 110 has a base body 112 and second magnetic means 111, which can be designed, for example, as permanent magnets. For the sake of clarity, only a few of the second magnetic means 111 are provided with reference numerals.The second magnetic means 111 can be arranged one behind the other on the surface of the base body 112 in the circumferential direction U, thus forming a ring. The first and second magnetic means 121, 111 are designed and spaced apart from one another by an air gap 150 such that they interact electromagnetically with one another in the operating state of the electric motor 100. More precisely, to operate the electric motor 100, the stator windings 121 are supplied with an electric current by means of a power source (not shown), which causes the windings 121 to generate corresponding magnetic fields, which interact electromagnetically with the magnetic fields of the permanent magnets 111 of the rotor 110.This is the reason why a torque acts on the permanent magnets 111, which results in the rotor 110 and, with it, the shaft 130 being set in rotation with a suitable design and arrangement of the aforementioned components. This concept, including the conditions for the design and precise arrangement of the magnetic means 111, 121 or of the rotor 110 and stator 120, are known per se and will therefore not be explained in more detail below. In electrical machines 100 such as the one shown here, losses arise, among other things, due to the limitation of the heat flow to the environment and the resulting heating of temperature-critical components, which, for example, limit the achievable power density on the one hand and, on the other hand, reduce the range when used in electric vehicle drives. For example, the losses occurring in the active material of the stator 120 can include hysteresis and eddy current losses.In order to reduce such losses, the active parts of electrical machines 100, i.e., the stator 120 or parts thereof and / or the rotor 110 or parts thereof, are laminated. The term "laminated" does not imply any restriction regarding the material to be used, but merely describes that the respective active part 110, 120 is constructed in multiple layers as described below. A "laminated" design of a component is to be understood such that - as indicated in FIG. 8 using the example of the stator 120 - the stator 120 and thus, for example, the stator teeth 122 consist of a plurality N of largely identical laminated layers 122 / i, which are stacked congruently on top of one another in the axial direction A. For the sake of completeness, it should be noted that the rotor 110 can also be constructed in a laminated manner in the same way, i.e.have a plurality of largely identical lamination layers that are stacked congruently on top of one another in the axial direction. However, this is not shown separately. Figure 8 represents a tangential view VIII of an exemplary stator tooth 122', randomly selected from the total number of stator teeth 122 of the stator 120, and of the corresponding lamination layers 122' / 1, 122' / 2, 122' / 3, etc., and insulation layers ISO corresponding to the section in the RA plane marked "VIII" in Figure 7. Purely by way of example, the stator 120 could, for example, and in practice, have an active length of 50 mm and be constructed from approximately N=300 lamination layers. However, the useful parameters depend heavily on the aircraft 1 for which the electric machine is to be used and on the configuration of the aircraft propulsion system 10. For the sake of clarity, not all N=300 positions 122' / i with i=1,…,N are shown in FIG. 8.provided with reference numerals. The stacked lamination layers 122' / i and insulation layers ISO form the material layer stack already mentioned several times, which forms the laminated core of the active part 110, 120 of the respective electrical machine 100 and which is thus composed of a plurality of individual material layers 122 / i. The material layer stack MS is constructed such that flat conductive layers 122' / i made of electrically and / or magnetically conductive material and flat insulation layers ISO alternate in the axial direction. In other words, the conductive layers 122' / i and the insulation layers ISO are applied to one another in the axial direction to form the material layer stack MS in such a way that at least one insulation layer ISO lies between two adjacent conductive layers 122' / i, 122' / i+1.The presence of the insulation layers ISO results in components of the current paths of the eddy currents W being interrupted in a direction perpendicular to the respective insulation layer ISO, and corresponding axial eddy currents being prevented. The insulation layers ISO can be produced, for example, by printing electrically insulating materials, e.g., plastic or ceramic-filled plastic, by anodizing, e.g., iron oxide, but also by printing Al layers, sintering, or anodizing to Al2O3. Alternatively, the insulation layers can be formed by insulating varnishes, e.g., baking varnish, or similar coatings. The conductive layers 122' / i are advantageously produced by a printing process, in particular by a screen, stencil, and / or roller printing process. For example, a screen printing process can be combined with a stencil printing process to produce screen-printed / stencil-printed layers 121' / i.A respective conductive layer 122' / i is preferably made of a soft magnetic material, in particular iron. 202208785 19 Consequently, the electric aircraft propulsion system 1, which comprises at least one electric machine 100, is manufactured by producing the conductive layers 122 / i using a printing process for at least one selected active part of the machine 100, which is to have a material layer stack MS as a laminated core, which in turn is composed of a plurality of flat conductive layers 122 / i and flat insulation layers ISO. The conductive layers 122 / i printed in this way and the insulation layers ISO are applied to one another in the axial direction to produce the material layer stack MS in such a way that at least one insulation layer ISO lies between two conductive layers 122 / i, 122 / i+1 of different material layers of the material layer stack MS.To operate an aircraft 1 with a propulsion group having at least one propulsion means 20, e.g., with one or more propellers, for generating propulsion for or driving the aircraft 1, the above-described electric aircraft propulsion system with the electric machines 100, 100g, 100m with specially manufactured material layer stacks with printed conductive layers 122 / i can be used. The machine group of the aircraft propulsion system 10 comprises a motor group with at least one such electric motor 100m, i.e., at least one 100m of the electric machines 100 of the machine group operates in one operating mode as an electric motor 100m. At least one of the propulsion means 20 of the propulsion group is then driven with one of the special electric motors 100m of the motor group to operate the aircraft 1.Preferably, the aircraft 1 has an internal combustion engine 30 in addition to the engine group, so that the aircraft propulsion system 10 can be operated as a hybrid-electric system. In this case, it can be provided that at least one drive means 20 of the drive means group is driven selectively by the internal combustion engine 30 and / or by at least one of the electric motors 100m of the engine group. This can be realized in such a way that the internal combustion engine 30 and the electric motor 100m act on different drive means 20 or propeller 20 of the drive means group or that the internal combustion engine 30 and the electric motor 100m can be connected to the same drive means 20 or propeller 20, wherein, for example, with the aid of a coupling, either one 30, 100m or the other motor 100m, 30 is coupled to the drive means 20.Furthermore, the operating method can include the drive means group comprising a plurality of drive means 20 and the motor group a corresponding plurality of electric motors 100m. Different electric motors 100m can be arranged and configured such that they drive different drive means 20 of the drive means group. In this case, different electric motors 100m of the motor group can be controlled separately. This means that the respective output power, via which, for example, the speed of the propeller 20 driven by the respective motor 100m can be controlled, is individually set for each propeller 20 by a control system of the aircraft 1. The special design of the electric motor 100m with the material layer stack MS made of printed material layers 122 / i allows rapid corrections of flight attitudes, for example in the case that the aircraft 1 is a multicopter.A further embodiment of the operating method relies on the fact that the machine group can additionally have an electric machine 100 designed as a generator 100g. In this case, the combustion engine 30 is used to drive the generator 100g, and the electrical energy thus provided by the generator 100g is used to operate the at least one electric motor 100m of the motor group. Since the above explanations referred to unmanned aircraft 1, it should be noted for the sake of completeness that the presented electric aircraft propulsion system 202208785 21 10 with the electric machines 100 with an active part with a material layer stack MS as a laminated core, which is constructed from a plurality of screen-printed / stencil-printed material layers, can in principle also be used for manned aircraft. The approach described here proposes the electric machine 100, e.g.The aim of the invention is to improve the electric motor 100m of an electric aircraft propulsion system 10 of an aircraft 1, e.g., for an unmanned aircraft 1, by using a printed, in particular screen-printed / stencil-printed material layer structure as the laminated core. Such material layers are described, for example, in EP3595148B1. The laminates are made of a soft magnetic material, in particular iron. Such print-based manufacturing processes allow sheet thicknesses on the order of 100µm, which results, for example, in strong eddy current suppression and a significant increase in efficiency.Furthermore, shorter and lighter electric machines 100 can be constructed, which has an extremely positive effect in the field of aviation in general and especially for use in unmanned aircraft, since drones typically have only a small installation space and any type of weight saving is essential for efficient operation and long range. Especially with multicopters, in which a large number of electric motors 100m are used, e.g. three, four, six, eight or even twelve motors 100m, it is not just weight and installation space that play a role. The rotors 120 used of the motors 100m are controlled with regard to their thrust or the torque applied via the electric motors 100m in such a way that a stable flight attitude is provided during takeoff and landing, in hovering and in transition. Electric motors which are equipped with a material layer stack MS with e.g.screen- / stencil-printed material layers 122 / i as a laminated core, have a higher torque than electric motors with conventional, punched laminated cores, which also results in advantages in terms of stability during flight.

Claims

202208785 23 patent claims 1. Electric aircraft propulsion system (10) for an aircraft (1), comprising at least one machine group with at least one electric machine (100, 100g, 100m), wherein each electric machine (100, 100g, 100m) of the machine group has an active part (110, 120) with a material layer stack MS as a laminated core, which comprises a plurality of material layers (122 / i, ISO) printed by a printing process, in particular a material transfer printing process, preferably a screen, stencil and / or roller printing process.

2. Electric aircraft propulsion system (10) according to claim 1, characterized in that the active part (110, 120) of a respective electric machine (100, 100g, 100m) of the machine group is a stator (120) or a rotor (110) or at least a part (122) of the stator (120) or the rotor (110) of the respective electric machine (100, 100g, 100m).Electric aircraft propulsion system (10) according to one of claims 1 to 2, characterized in that the plurality of material layers (122 / i, ISO) of the material layer stack MS has flat, conductive layers (122 / i) and flat insulation layers (ISO), wherein the plurality of flat material layers (122 / i, ISO) of the material layer stack MS are stacked on top of one another in the axial direction in such a way that at least one insulation layer (ISO) lies between each two conductive layers (122 / i, 122 / i+1).

4. Electric aircraft propulsion system (10) according to claim 3, characterized in that the conductive layers (122 / i) are material layers printed using the printing method.

5. Electric aircraft propulsion system (10) according to one of claims 3 to 4, characterized in that the conductive. 202208785 24 capable layers (122 / i) consist of a soft magnetic material, in particular of iron.

6. Electric aircraft propulsion system (10) according to one of claims 1 to 5, characterized in that the aircraft (1) is an unmanned aircraft, in particular a drone.

7. Electric aircraft propulsion system (10) according to claim 6, wherein the unmanned aircraft (1) is a multicopter with a plurality of propulsion means (20), wherein the machine group comprises a first plurality of electric machines (199, 100g, 100m), wherein a respective electric machine (100m) of the first plurality is designed to drive a respective propulsion means (20) and is mechanically coupled to the respective propulsion means (20) for this purpose.

8. Electric aircraft propulsion system (10) according to one of claims 1 to 7, characterized in thatthat the electric aircraft propulsion system (10) is a hybrid-electric propulsion system for driving a propulsion means (20) of the aircraft (1), wherein - at least one of the electric machines (100) of the machine group is configured in an operating mode as an electric motor (100m) to drive the propulsion means (20) and is coupled or can be coupled to the propulsion means (20) in order to drive it, - the aircraft propulsion system (10) has an internal combustion engine (30), wherein the internal combustion engine (30) is integrated into the aircraft propulsion system (10) in such a way that it is coupled or can be coupled to one of the electric machines (100) of the machine group, which in an operating mode is configured as a generator (100g) to provide electrical energy, in order to drive this (100g) so that it provides electrical energy, and / or, 202208785 25 - is coupled or can be coupled to the drive means (20) of the aircraft (1) in order to drive the aircraft (1).

9. Use of a material layer stack MS comprising a plurality of material layers (122 / i, ISO) printed using a printing process, in particular a screen, stencil, or roll printing process, as a laminated core for at least one active part (110, 120) of at least one electrical machine (100, 100g, 100m) of an electric aircraft propulsion system (10) according to one of claims 1 to 8 of an aircraft (1). 10.Manufacturing method for an electric aircraft propulsion system (10) according to one of claims 1 to 8, comprising at least one electric machine (100, 100m, 100g), wherein the electric machine (100, 100m, 100g) has an active part (110, 120) with a material layer stack MS as a laminated core, which has a plurality of material layers (122 / i, ISO), comprising planar conductive layers (122 / i) and planar insulation layers (ISO), wherein - the conductive layers (122 / i) are produced using a printing process, in particular a screen, stencil or roller printing process, - the thus printed conductive layers (122 / i) and the insulation layers (ISO) are applied to one another in the axial direction to produce the material layer stack MS in such a way that between two conductive layers (122 / i, 122 / i+1) of different material layers of the material layer stack MS, at least one insulation layer (ISO) is located. 11.Operating method for an aircraft (1) with an electric aircraft propulsion system (10) according to one of claims 1 to 8 and with a drive means group with at least one drive means (20) for driving the aircraft (1), wherein the machine group comprises a motor group with at least one electric motor (100m), wherein each. 202208785 26 The drive means (20) of the drive means group is driven by an electric motor (100m) of the motor group.

12. Operating method according to claim 11, characterized in that the aircraft (1) is an unmanned aerial vehicle, in particular a drone.

13. Operating method according to claim 12, characterized in that the aircraft (1) has an internal combustion engine (30) in addition to the motor group, wherein the drive means group is selectively driven by the internal combustion engine (30) and / or by at least one of the electric motors (100m) of the motor group. 14.Operating method according to one of claims 11 to 13, wherein the drive means group comprises a plurality of drive means (20) and the motor group comprises a plurality of electric motors (100m), wherein different electric motors (100m) are arranged and configured such that they drive different drive means (20), and wherein the different electric motors (100m) of the motor group are controlled separately.

15. Operating method according to one of claims 13 to 14, wherein the machine group additionally has an electric machine designed as a generator (100g), wherein - the internal combustion engine (30) is used to drive the generator (100g) and - the electrical energy thus provided by the generator (100g) is used to operate the at least one electric motor (100m) of the motor group.

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