WO2023208829A1

WO2023208829A1 - Propulsion system for an aircraft

Info

Publication number: WO2023208829A1
Application number: PCT/EP2023/060621
Authority: WO
Inventors: Guido WORTMANN
Original assignee: Rolls-Royce Deutschland Ltd & Co Kg
Priority date: 2022-04-29
Filing date: 2023-04-24
Publication date: 2023-11-02
Also published as: DE102022110556A1

Abstract

A propulsion system (1A; 1B), more particularly for an aircraft (2), comprises: a number of rotors (12), which are disposed in at least four sectors (Q1-Q4), each of the rotors (12) being assigned to a pair (P) of rotors (12) which are disposed in different sectors (Q1-Q4), and a number of energy sources (11), wherein the rotors (12) of each pair (P) can be driven by energy from different energy sources (11) and wherein each of the energy sources (11) provides energy for driving at least one rotor (12) in each of the sectors (Q1-Q4).

Description

Propulsion system for an aircraft

Description

The present disclosure relates in particular to a propulsion system, to an aircraft with such a propulsion system and to a method for electrically connecting a propulsion system.

Propulsion systems for aircraft are used in a variety of designs. Combustion engines, e.g. piston engines or gas turbine engines, enable long ranges and high speeds. Drive devices with an electric motor enable the use of sustainably generated energy and are sometimes particularly low-maintenance and quiet. Advances in battery and fuel cell technology are enabling ever wider areas of application for electric drive systems.

Vertical take-off and landing aircraft, e.g. airplanes, are regularly referred to as VTOL aircraft, with the abbreviation VTOL being derived from “Vertical Take-Off and Landing”. VTOL aircraft are trained for vertical takeoff and landing.

WO 2020/141513 A2 describes a VTOL aircraft in which pairs of drive motors opposite each other with respect to a center of gravity of the aircraft are powered by the same energy source. This is intended to ensure that the aircraft remains as stable as possible if the energy source fails during flight. In the aviation sector, defects in components can have particularly serious consequences. It is therefore always desirable to create drive systems that are as safe as possible. At the same time, however, it is also desirable for all components of the aircraft to have the lowest possible weight in order to achieve the greatest possible range. However, these two requirements are usually mutually exclusive, as additional safety devices often result in additional weight.

The object of the present invention is to provide an improved drive system.

According to one aspect, a propulsion system, in particular for an aircraft, is provided, comprising a plurality of rotors arranged in at least four sectors, each of the rotors being associated with a pair of rotors arranged in different ones of the sectors, and a plurality of energy sources. It is envisaged that the rotors of each pair can be driven by energy from different energy sources, with each of the energy sources providing energy to drive at least one rotor in each of the sectors.

This makes it possible that in the event of a loss of power on one of the rotors, for example as a result of a defect in a drive motor of one of the rotors, a drive motor of the other of the rotors of the pair can be reduced accordingly, so that as a result the consumption of energy from the two energy sources connected to the drive motors of this pair of rotors is similarly reduced, without the need for reconfiguration of the connections between energy sources and drive motors. Furthermore, this makes it possible for the failure of one of the energy sources to have particularly small effects with regard to rolling and tilting of the drive system, in particular of an aircraft with the drive system. Since the energy storage devices are thus emptied particularly evenly, smaller reserves are sufficient and, as a result, particularly small energy storage devices can be used with regard to the power required by the respective energy storage device. Furthermore, if an energy storage device fails, only minimal corrective movements are possible Reference to rolling and tilting is necessary, which also enables the use of relatively small drive motors. This makes it possible to create a drive system that is both powerful and low in weight.

Each of the energy sources may provide energy to drive the same number of rotors in each of the sectors. This enables a particularly good balance.

For example, the sectors are arranged around a point. This allows particularly stable take-offs and landings and this is where the advantages mentioned above come into their own.

The two rotors (and optionally their drive motors) of each pair can be arranged on opposite sides of the point, optionally symmetrically to one another. For example, the two rotors (especially their axes of rotation) and the point lie on a straight line. Optionally, this applies to all of the rotors in relation to the respective pairs. This allows particularly minimized corrective movements in terms of rolling and tilting in the event of a drive motor failure. In principle, the rotor pairs can be chosen so that the moments of the rotors (buoyant force x lever arm) around the point (e.g. center of gravity) essentially or completely cancel each other out. With identical rotors (assuming the same buoyancy force provided), this can be achieved by the aforementioned symmetrical arrangement, in particular the same length of the lever arms and the opposite position. However, the condition that the rotors of a (each) pair have equal moments can also be achieved by choosing different factors. For example, a rotor that is drivable with a higher (maximum) driving force and is arranged according to a shorter lever arm (closer to the point) can be combined with a rotor that is drivable with a comparatively lower (maximum) driving force and is arranged according to a longer lever arm (further away from the point) can be combined into a pair.

Each of the rotors may be driven by a respective drive motor connected to the corresponding power source. In one embodiment, each of the drive motors has several strands that are electrically separated from one another. The multiple strands are connected, for example, to different energy sources (eg electrical). The rotor of the drive motor can be driven by applying electrical current to any one of the (or both) strands. This makes it possible to achieve a particularly high level of reliability.

Optionally, the drive motor strands of each pair are connected to a different one of the energy sources. In this case, four or more energy sources are provided. This enables further increased reliability.

Optionally, each of the drive motors is an electric motor. This makes it possible to achieve a particularly sustainable drive system.

The drive system can include a control unit. The control unit can be set up to detect a drop in power on one of the drive motors. Optionally, in response, the control unit reduces a power consumption of the other drive motor of the corresponding pair of rotors in accordance with the detected drop in power. As a result, uniform consumption of energy stored in the energy sources and stable flight behavior can be achieved with just one measure.

Each of the rotors has an axis of rotation about which the respective rotor can be rotated. It can be provided that the axes of rotation of the rotors are aligned or can be aligned parallel to one another. In this way, particularly strong buoyancy can be generated.

Each of the rotors can have blades and, for example, be designed in the form of a propeller. This can generate thrust.

Optionally, the drive system includes (at least or exactly) eight rotors (in particular each with a corresponding drive motor) and (at least or exactly) two energy sources. This enables a particularly low weight with a high level of reliability at the same time. Each of the energy sources can be a battery. Batteries can be recharged very frequently and quickly without using fuel.

According to one aspect, an aircraft is provided comprising the propulsion system according to any embodiment described herein. The propulsion system generates lift (optionally also thrust) for the aircraft. The advantages mentioned above are particularly noticeable in an aircraft.

The aircraft is designed, for example, as a VTOL aircraft, in particular as a VTOL aircraft. A VTOL aircraft particularly benefits from the advantages of the propulsion system described above.

The sectors can be arranged around a point. The point represents, for example, the center of gravity of the aircraft. This makes particularly stable flight possible even if a drive motor and/or an energy source fails.

According to one aspect, a method for electrically connecting a drive system is provided, in particular the drive system according to any embodiment described herein. The drive system includes a plurality of rotors arranged in at least four sectors, each of the rotors being associated with a pair of rotors arranged in different ones of the sectors and driven by a respective drive motor, and a plurality of power sources. The method includes connecting the drive motors of each pair of rotors to a different one of the power sources and connecting each of the power sources to at least one drive motor of a corresponding rotor in each of the sectors.

Embodiments will now be described by way of example with reference to the figures; in the figures show in schematic representations:

Figure 1 shows an aircraft in the form of a VTOL aircraft with several electrically driven rotors; Figure 2 shows a pairwise assignment of the rotors of the aircraft according to Figure 1;

Figure 3 shows a connection of drive motors of the rotors

Aircraft according to Figure 1 to one of several energy sources;

Figure 4 shows a connection of alternatively designed drive motors for the aircraft according to Figure 1 to two of several energy sources; and

Figure 5 is a schematic sectional view of one of the

Drive motors according to Figure 4 in the form of a permanently excited, three-phase electrical machine as an internal rotor.

Figure 1 shows an aircraft 2 in the form of an electrically powered aircraft with a fuselage 20 and wings 21 in a top view from above.

The aircraft 2 comprises a drive system 1A with a plurality of rotors 12, in the present case each in the form of a propeller, which are each driven by a respective drive motor 10A. The rotors 12 each include several, here as an example two blades 120. In alternative embodiments, the aircraft 2 includes, for example, fans instead of propellers. The drive motors 10A and the rotors 12 are mounted on the two wings 21 of the aircraft 2. The aircraft 2 also has a point X, which represents the center of mass of the aircraft 2. The point X is located between the rotors 12 and the drive motors 10A.

Each of the propellers 12 can be rotated about a respective axis of rotation R. The rotors 12 are all identical in the example shown. The rotors 12 are arranged symmetrically. The axes of rotation R of all rotors 12 are aligned parallel to one another as shown in FIG. This allows the aircraft 2 to take off and load vertically. Optionally, several (or all) of the rotors 12 can be pivoted to create a thrust into a forward movement after an upward movement.

Specifically, the drive system 1A includes eight rotors 12 and eight drive motors 10A. Each rotor 12 is assigned its own drive motor 10A and the rotor 12 can be driven by its drive motor 10A. In the present case, the drive motors 10A are aligned coaxially with the respective rotor 12.

In the present case, the drive motors 10A are each designed in the form of an electric motor, with hybrid-electric versions also being conceivable, for example. Furthermore, the drive system 1A comprises several, namely in the present case two, independent energy sources 11. Each of the energy sources 11 comprises a rechargeable electric battery. Alternatively, for example, one energy source 11 is designed in the form of a battery and the other of the energy sources 11 is designed in the form of an internal combustion engine with a generator. The energy sources 11 supply electrical power to operate the drive motors 10A. The energy sources

11 can be designed in the same way. Alternatively, the energy sources 11 are designed differently.

A control unit 14 of the drive system 1A controls the drive motors 10A and the energy sources 11.

Figure 2 shows the rotors 12 of the aircraft 2 and illustrates that the rotors

12 are arranged in four sectors Q1 -Q4. The sectors Q1 -Q4 form four quadrants around the point X. A first sector Q1 is arranged in relation to the aircraft 2 at the front left (VL), a second sector Q2 at the front right (VR), a third sector Q3 at the rear left (HL) and a fourth sector Q4 at the rear right (HR).

Two rotors 12 are arranged in each of the sectors Q1 -Q4, which are numbered consecutively in Figure 2 for easier reference. The rotors 12 No. 1 and No. 2 are arranged in the first sector Q1. In the second sector Q2 the rotors 12 No. 3 and No. 4, in the third sector Q3 the rotors 12 No. 5 and No. 6 and in the fourth sector Q4 the rotors 12 No. 7 and No. 8. The rotors 12 are there arranged in two rows, with rotors No. 1 to No. 4 arranged in a front row and rotors 12 No. 5 to No. 8 in a back row. In Figure 2, a pair P of two rotors 12 is further illustrated by a dashed line. In the present case, the rotor 12 No. 1 and the rotor 12 No. 8 form the pair P. Further pairs form the rotor 12 No. 4 and the rotor 12 No. 5, as well as the rotor 12 No. 2 and the rotor 12 No. 7, as well as the rotor 12 No. 3 and the rotor 12 No. 6.

For each of the pairs P, a straight line, which connects the axes of rotation R of the two rotors 12 of the respective pair P, passes through the point X. However, it should be noted that this order corresponds to a special case and does not necessarily have to exist. It is also conceivable that some or all of the connecting lines do not pass through point X. The two rotors 12 of each pair P are therefore arranged symmetrically to one another on opposite sides of the point X. The drive system 1A includes exactly four pairs P of rotors 12.

Furthermore, it is illustrated in Figure 2 that rotors 12 are provided in each of the sectors Q1 -Q4, which are driven in opposite directions compared to one another. This allows particularly stable flight behavior.

For each of the pairs P it also applies that the drive motor 10A of one of the two rotors 12 is electrically connected (only) to one of the two energy sources 11, while the drive motor 10A of the other of the two rotors 12 (only) to the other of the two energy sources 11 is electrically connected. The rotors 12 of each pair P can be driven by energy from different energy sources 11.

This is illustrated with reference to FIG. 3, in which it is shown by a dashed line and a dash-dotted line which of the rotors 12 can be driven using energy from one energy source 11 and which of the rotors 12 can be driven using energy from the other of the energy sources 11.

The rotors 12 No. 1, 6, 7 and 4 can (only) be driven by energy from one of the energy sources 11 (dashed line) and the respective drive motors 10A are (only) electrically connected to one of the energy sources 11. The In contrast, rotors 12 Nos. 5, 2, 3 and 8 can be driven (only) by means of energy from the other of the energy sources 11 (dash-dotted line) and the respective drive motors 10A are (only) electrically connected to the other of the energy sources 11.

Each of the energy sources 11 provides energy for driving the same number of rotors, namely in the present case (exactly) one rotor 12, in each of the sectors Q1 -Q4.

The drive system 1A has an even number of rotors 12. Each of the rotors 12 is (only) assigned to exactly one pair P of rotors 12. Each pair P consists of two rotors 12 diagonally opposite each other with respect to point X.

The connection of the energy sources 11 to the drive motors 10A of the rotors 12 is therefore carried out according to two rules. According to the first rule, the rotors 12 of each pair P are not driven with energy from the same energy source 11, but with energy from two different energy sources 11. According to the second rule, an energy source is symmetrically assigned to the same number of rotors 12 in each of the sectors Q1 - Q4 (and these rotors 12 are drivable by energy from this energy source).

The following steps are provided in a method for electrically connecting the drive system 1A:

Connecting the drive motors 10A of each pair P of rotors 12 to a different one of the energy sources 11 and connecting each of the energy sources 11 to at least one drive motor 10A of a corresponding rotor 12 in each of the sectors Q1 - Q4 according to the dashed and dash-dotted lines of Figure 3.

The already mentioned control unit 14 is set up to detect a drop in power on one of the drive motors 10A and, in response, to reduce a power consumption of the other drive motor 10A of the corresponding pair P of rotors 12 in accordance with the detected drop in power. Figure 4 illustrates a drive system 1B for the aircraft 2, which is designed according to the drive system 1A according to Figures 1 - 3, in contrast to which each of the drive motors 10B has several, namely two strands S1 -S4, which are connected to different energy sources 11 are connected.

The strands S1 -S4 of the drive motors 10B of each pair P of rotors 12 are each connected to a different one of the energy sources 11. Consequently, the drive system 1B according to FIG. 4 comprises four energy sources 11. The strands S1 -S4 are each connected as stated above with reference to Figure 3.

5 shows a schematic sectional view of one of the drive motors 10B of the drive system 1B according to FIG. 4 in the form of an electric motor, specifically a permanently excited synchronous machine, the embodiment shown in FIG.

From Figure 5 it can be seen that the drive motor 10B is designed as an internal rotor; However, this is only to be understood as an example. The drive motors 10A shown in Figures 1 - 3 are external rotors and the drive motor 10B can also be designed as an external rotor. The drive motor 10B includes a stator 100, which has an undesignated opening, in particular a through opening, in which a rotor 101 is rotatably mounted.

The stator 100 comprises a body, for example in the form of a laminated core, on which stator teeth are formed. The stator teeth protrude radially from the body, in this case radially inwards. The stator 100 includes stator windings wound around several of the stator teeth. In the present case, the stator windings are designed for three-phase operation, that is, connected to a three-phase alternating voltage with phases U, V, W. When the drive motor 10B is operating as intended, the stator winding is correspondingly supplied with the alternating voltage.

In the present case, the rotor 101 is designed as a salient pole rotor, which includes permanent magnets to provide the magnetic flux. In the present one The embodiment provides that the rotor 101 has exactly one magnetic north pole N and one magnetic south pole S. In alternative embodiments, more magnetic poles can also be provided alternately in the circumferential direction around an axis of rotation of the rotor 101.

The rotor 101 is rotatably mounted. The three-phase alternating voltage, the phases U, V, W of which are each phase-shifted by 120°, generates a rotating magnetic field during normal operation, which interacts with the permanently excited magnetic field provided by the rotor 101, so that in motor operation a corresponding rotational movement of the rotor 101 compared to the stator 100 can be brought about. Optionally, the drive motor 10B can be operated as a generator (for recuperation). 5 shows schematically the sections of the stator windings that are assigned to the respective phases U, V, W.

The stator windings of the drive motor 10B are connected to two three-phase, independent inverters 13. The inverters 13 provide the electrical alternating voltage with the three phases U, V, W. The inverters 13 obtain the electrical energy required for intended operation from an energy source 11 connected to (only) one of the two inverters 13. The energy sources 11 are electrically separated from one another and can be operated independently of one another. In the present embodiment, each of the energy sources 11 is a DC voltage source that generates and/or stores electrical energy and in the present case comprises an electrical energy storage device, for example an accumulator. Alternatively or additionally, the energy sources can each include fuel cells, an internal combustion engine with a generator and/or the like.

5 further illustrates that one of the energy sources 11 is electrically connected to a stator winding via a first strand S1, and that another of the energy sources 11 is electrically connected to another stator winding via a second strand S2. Alternatively, each drive motor has more than two strands, eg three or four strands, each powered by different (not the same) energy sources. It is to 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 unless they are mutually exclusive, and the disclosure extends to and includes all combinations and subcombinations of one or more features described herein.

For example, the drive system 1A; 1 B can not only be used for aircraft 2 but also for watercraft, for example.

Reference symbol list

1A; 1 B drive system 10A; 10B Drive motor 100 Stator 101 Rotor 11 Power source 12 Rotor 120 Blade 13 Inverter 14 Control unit 2 Aircraft 20 Fuselage 21 Wing G1 , G2 Group P Pair Q1-Q4 Sector R Rotation axis S1-S4 Strand X Point

Claims

Expectations

1. Drive system (1A; 1B), in particular for an aircraft (2), comprising: a plurality of rotors (12) which are arranged in at least four sectors (Q1 -Q4), each of the rotors (12) being a pair (P ) is assigned to rotors (12) arranged in various of the sectors (Q1 -Q4), and a plurality of energy sources (11), the rotors (12) of each pair (P) being drivable by energy from various of the energy sources (11) and each of the energy sources (11) provides energy for driving at least one rotor (12) in each of the sectors (Q1 -Q4).

2. Drive system (1A; 1B) according to claim 1, wherein each of the energy sources (11) provides energy for driving the same number of rotors (12) in each of the sectors (Q1 -Q4).

3. Drive system (1A; 1B) according to claim 1 or 2, wherein the sectors (Q1 -Q4) are arranged around a point (X).

4. Drive system (1A; 1B) according to claim 3, wherein the two rotors (12) of each pair (P) are arranged on opposite sides of the point (X).

5. Drive system (1A; 1B) according to one of the preceding claims, wherein each of the rotors (12) is driven by a respective drive motor (10A, 10B) which is connected to the corresponding energy source (11).

6. Drive system (1 B) according to claim 5, wherein each of the drive motors (1 OB) has a plurality of electrically separate strands (S1 -S4) which are connected to different energy sources (11).

7. Drive system (1 B) according to claim 6, wherein the strands (S1 -S4) of the drive motors (1 OB) of each pair (P) of rotors (12) are connected to one other of the energy sources (11) are connected.

8. Drive system (1A; 1B) according to one of claims 5 to 7, wherein the drive motors (10A, 10B) are each electric motors.

9. Drive system (1A; 1B) according to one of claims 5 to 8, comprising a

Control unit (14), which is set up to detect a drop in power on one of the drive motors (10A; 10B) and in response to this, a power consumption of the other drive motor (10A; 10B) of the corresponding pair (P) of rotors (12) in accordance with the detected drop in performance.

10. Drive system (1A; 1B) according to one of the preceding claims, wherein each of the rotors (12) has an axis of rotation (R), the axes of rotation (R) of the rotors (12) being aligned or alignable parallel to one another.

11. Drive system (1A; 1B) according to one of the preceding claims, wherein each of the rotors (12) has blades (120) and is designed in the form of a propeller.

12. Drive system (1A; 1B) according to one of the preceding claims, comprising eight rotors (12) and two energy sources (11).

13. Drive system (1A; 1B) according to one of the preceding claims, wherein the energy sources (11) are each a battery.

14. Aircraft (2), comprising the drive system (1A; 1B) according to one of the preceding claims.

15. Aircraft (2) according to claim 13, wherein the aircraft (2) is designed as a VTOL aircraft.

16. Aircraft (2) according to claim 14 or 15, wherein the sectors (Q1 -Q4) around are arranged around a point (X) and the point (X) represents the center of gravity of the aircraft. Method for electrically connecting a drive system (1A; 1B), in particular the drive system (1A; 1B) according to one of claims 1 to 13, comprising a plurality of rotors (12) which are arranged in at least four sectors (Q1 -Q4). , wherein each of the rotors (12) is assigned to a pair (P) of rotors (12) arranged in different sectors (Q1 -Q4) and is driven by a respective drive motor (10A; 10B), and a plurality of energy sources (11), the procedure comprising:

Connecting the drive motors (10A, 10B) of each pair (P) of rotors (12) to a different one of the energy sources (11) and connecting each of the energy sources (11) to at least one drive motor (10A, 10B) of a corresponding rotor (12 ) in each of the sectors (Q1-

Q4).