DEVICE FOR GENERATING ELECTRIC ENERGY FOR AN AIRCRAFT AND AIRCRAFT

Description

[0001] The present disclosure relates to a device for generating electrical energy for an aircraft and to an aircraft with such a device.

[0002] In recent years, efforts have increasingly focused on replacing existing transportation systems, whose propulsion systems convert fossil fuels into mechanical energy, with more environmentally friendly systems. This applies to both land vehicles and aircraft, for which suitable, environmentally compatible propulsion technologies are also being developed.

[0003] Besides purely electric propulsion systems, hybrid propulsion systems also represent efficient aircraft propulsion systems that emit significantly fewer pollutants and conserve fuel resources compared to current propulsion systems. However, due to the currently unfavorable weight-to-energy ratio of traction batteries, purely electric flight is only viable for a very limited range of applications. Electric aircraft are therefore currently being equipped with additional energy converters and storage systems to achieve acceptable ranges and propulsion performance at moderate costs.

[0004] Hybrid electric drive systems with small energy generators for range extension are considered a viable propulsion concept for the future. Various concepts are available for use as range extenders, enabling the conversion of chemical energy into electrical energy. The specifications of a range extender depend heavily on the requirements of future propulsion concepts. This means that installation space, weight, cost, and multi-fuel capability will be given newly defined weightings in the selection process for the energy converter.

[0005] The development and application of alternative energy conversion concepts are currently considered promising for improving, for example, the range of electrically powered small aircraft. Currently known concepts include devices consisting of a combination of a generator and a gas turbine driving the generator.

[0006] However, the known devices require a large amount of installation space and have a low power density, which also negatively impacts the energy consumption of an aircraft equipped with them. Devices that partially exhibit the features of the present articles are known from US 2022 / 136402 A1, US 2008 / 184694 A1, and US 2013 / 219907 A1.

[0007] The present disclosure is based on the objective of providing a space-saving device with a high power density for generating electrical energy for an aircraft, as well as an aircraft that has the lowest possible energy consumption.

[0008] This problem is solved with a device and with an aircraft having the features of claim 1 and 6 respectively.

[0009] According to a first aspect, a device for generating electrical energy for an aircraft is proposed, comprising an electric machine and a gas turbine unit. The gas turbine unit is designed with a compressor unit, a combustion chamber unit, and a turbine unit comprising at least one high-pressure turbine and one low-pressure turbine.

[0010] The compressor unit is coupled to the high-pressure turbine via a high-pressure shaft, while the low-pressure turbine is directly connected to an output shaft of the electric machine via a low-pressure shaft. The high-pressure shaft, the low-pressure shaft, and the output shaft of the electric machine are arranged coaxially in a space-saving manner. During operation of the gas turbine system, the high-pressure and low-pressure shafts rotate in opposite directions. The electric machine can be operated as a generator to produce electrical energy and as a motor to start the gas turbine system, thus enabling the device according to the present disclosure to be implemented in a simple, space-saving, and cost-effective manner without an additional starter unit. Consequently, the device exhibits a higher power density compared to known devices.

[0011] Additionally, the output shaft is connected to the high-pressure shaft via a gear unit and a freewheel. The freewheel disconnects the connection between the output shaft of the electric machine and the high-pressure shaft when torque is flowing from the high-pressure shaft towards the output shaft.

[0012] This allows the necessary reversal of rotation in the gearbox, required for driving the high-pressure shaft with the electric machine, to be achieved with minimal design complexity. Additionally, the freewheel, without requiring any extra control or regulation, allows the functional connection between the electric machine and the high-pressure shaft to be interrupted in the freewheel area when the gas turbine is engaged and the high-pressure shaft rotates at a higher speed than the low-pressure shaft. In this state, the electric machine can then be driven by the low-pressure turbine connected via the low-pressure shaft and can generate the desired amount of electrical energy in generator mode without undesirably affecting the operation of the high-pressure turbine.

[0013] The transmission unit comprises a first spur gear stage with a first spur gear connected to the output shaft and meshing with a second spur gear. The second spur gear is non-rotatably connected to a shaft that is coupled to a first clutch half of the freewheel.

[0014] The transmission unit has a second spur gear stage and a third spur gear stage. A first spur gear of the second spur gear stage is arranged on a shaft that is non-rotatably connected to a second coupling half of the freewheel.

[0015] A second spur gear of the second spur gear stage can be connected in a structurally simple and cost-effective manner via a shaft to a first spur gear of the third spur gear stage, which meshes with a second spur gear of the third spur gear stage that is in rotationally fixed contact with the high-pressure shaft.

[0016] If the first spur gear of the second spur gear stage meshes with another spur gear of an auxiliary gear unit, then the auxiliary gear unit can be driven by the motor-driven electric machine during the start-up process of the gas turbine unit and, when the gas turbine unit is switched on, by the high-pressure turbine via the high-pressure shaft.

[0017] In a further embodiment of the device according to the present disclosure, which has a high power density, a spur gear of the auxiliary device transmission device engages with the gear of the auxiliary device transmission device, via which at least one auxiliary unit can be driven.

[0018] In an embodiment of the device according to the present disclosure, characterized by a small installation space requirement in the radial direction, the gear unit is arranged in the axial direction of the output shaft between the electric machine and the compressor unit.

[0019] Furthermore, an aircraft is described which is equipped with a device designed in the manner described above and can therefore be operated with low energy consumption while having a long range.

[0020] It is clear to a person skilled in the art that a feature or parameter described in relation to one of the aspects above can be applied to any other aspect, provided they are not mutually exclusive. Furthermore, any feature or parameter described herein can be applied to any aspect and / or combined with any other feature or parameter described herein, provided they are not mutually exclusive. However, it should be noted that the subject matter of the claimed invention is defined in the attached claims.

[0021] The present disclosure is not limited to the specified combinations of features of the dependent or suffixed claims. Furthermore, it is possible to combine individual features, even those that arise from the claims, the subsequent description of embodiments, and directly from the drawing. As in the previous paragraph, it must be taken into account that the subject matter of the claimed invention is defined in the appended claims.

[0022] The reference of the claims to the drawings by means of reference numerals shall not limit the scope of protection of the claims.

[0023] Preferred embodiments are described in the dependent claims and the following description. Exemplary embodiments of the subject matter according to the present disclosure are explained in more detail with reference to the drawing, without being limited thereto.

[0024] The single figure in the drawing shows a highly schematic longitudinal section view of a device for an aircraft for generating electrical energy, the device comprising a motor- and generator-operable electric machine and a gas turbine unit coupled thereto.

[0025] The figure shows a device 1 for generating electrical energy for an aircraft (not shown in detail) with an electric machine 2 and an associated gas turbine assembly 3 in a highly simplified longitudinal section view. The gas turbine assembly 3 comprises a combustion chamber unit 4, a compressor unit 5, and a turbine unit 6, which includes a high-pressure turbine 7 and a low-pressure turbine 8. In the compressor unit 5, air is compressed and introduced into the combustion chamber unit 4, where fuel is added to the compressed air. The fuel-air mixture is ignited in the combustion chamber unit 4. The air, heated by combustion, exits towards the high-pressure turbine 7, expands there, and drives the high-pressure turbine 7. Subsequently, the air flows through the low-pressure turbine 8 and drives it.

[0026] The compressor unit 5 is coupled to the high-pressure turbine 7 via a high-pressure shaft 9 and is thus driven by it during operation of the gas turbine unit 3. The low-pressure turbine 8 is directly connected to an output shaft 11 of the electric machine 2 via a low-pressure shaft 10 and thus drives the electric machine 2 when the gas turbine unit 3 is engaged. In generator mode, the electric machine 2 produces electrical energy and supplies an aircraft's electric propulsion system with electrical energy, preferably also supplying an onboard electrical system and an electrical storage unit of the aircraft with electrical energy.

[0027] The high-pressure shaft 9, the low-pressure shaft 10, and the output shaft 11 of the electric machine 2 are arranged coaxially. During operation of the gas turbine unit 3, the high-pressure shaft 9 and the low-pressure shaft 10 rotate in opposite directions, which is why the turbine unit can be operated with high efficiency.

[0028] The electric machine 3 can also be operated as a motor to start the gas turbine unit 3. To start the gas turbine unit 3, the output shaft 11 is connected to the high-pressure shaft 9 via a gear unit 12 and a freewheel 13. The gear unit 12 is arranged axially to the output shaft 11 between the electric machine 2 and the compressor unit 5. The freewheel 13 disconnects the connection between the output shaft 11 of the electric machine 2 and the high-pressure shaft 9 when torque is applied from the high-pressure shaft 9 towards the output shaft 11.

[0029] The gear unit 12 comprises a first spur gear stage 14, which has a first spur gear 15 connected to the output shaft 11 and meshing with a second spur gear 16 of the first spur gear stage 14. The second spur gear 16 of the first spur gear stage 14 is non-rotatably connected to a shaft 17, which is coupled to a first clutch half 18 of the freewheel 13. The gear unit 12 further comprises a second spur gear stage 19 and a third spur gear stage 20. A first spur gear 21 of the second spur gear stage 19 is arranged on a shaft 22, which is non-rotatably connected to a second clutch half 23 of the freewheel 13.

[0030] A second spur gear 24 of the second spur gear stage 19 is connected via a shaft 25 to a first spur gear 26 of the third spur gear stage 20 in a rotationally fixed manner, which meshes with a second spur gear 27 of the third spur gear stage 20 which is in rotationally fixed contact with the high-pressure shaft 7.

[0031] Additionally, the first spur gear 21 of the second spur gear stage 19 meshes with another spur gear 28 of an auxiliary gear unit 29. The gear 28 of the auxiliary gear unit 29 engages with a spur gear 30 of the auxiliary gear unit 29, which is rotationally fixed on a shaft 31 of an auxiliary assembly 32. The auxiliary assembly 32 can be driven by the high-pressure shaft 9 via this shaft. The auxiliary assembly 32 can be, for example, a fuel pump, hydraulic pump, or the like. Reference symbol list

[0032] 1 Device 2 Electric machine 3 Gas turbine device 4 Combustion chamber unit 5 Compressor unit 6 Turbine unit 7 High-pressure turbine 8 Low-pressure turbine 9 High-pressure shaft 10 Low-pressure shaft 11 Output shaft 12 Gearbox unit 13 Freewheel 14 First spur gear stage of the gearbox 15 First spur gear of the first spur gear stage 16 Second spur gear of the first spur gear stage 17 Shaft between the second spur gear of the first spur gear stage and the first clutch half of the freewheel 18 First clutch half of the freewheel 19 Second spur gear stage of the gearbox unit 20 Third spur gear stage of the gearbox 21 First spur gear of the second spur gear stage 22 Shaft between the first spur gear of the second spur gear stage and the second clutch half of the freewheel 23 Second clutch half of the freewheel 24 Second spur gear of the second spur gear stage 25 Shaft between the second spur gear of the second spur gear stage and the spur gear 26 of the third spur gear stage 26 first spur gear of the third spur gear stage 27 second spur gear28 third spur gear stage 29 auxiliary gear unit 30 spur gear of the auxiliary gear unit 31 shaft of the auxiliary unit 32 auxiliary unit

Claims

1. Device (1) for generating electrical energy for an aircraft with an electrical machine (2) and with a gas turbine device (3) with a compressor unit (5), with a turbine unit (6) with at least one high-pressure turbine (9) and with a low-pressure turbine (8) and with a combustion chamber unit (4), wherein the compressor unit (5) is coupled to the high-pressure turbine (7) via a high-pressure shaft (9), wherein the low-pressure turbine (8) is connected directly to an output shaft (11) of the electrical machine (2) via a low-pressure shaft (10), wherein the high-pressure shaft (9), the low-pressure shaft (10) and the output shaft (11) of the electrical machine (11) are arranged coaxially with respect to one another, wherein the high-pressure shaft (9) and the low-pressure shaft (10) rotate in different directions of rotation during operation of the gas turbine device (3), wherein the electrical machine (2) is operable by a generator to generate electrical energy, wherein the electrical machine (2) is operable by a motor to start the gas turbine device (3) and the output shaft (11) is connected to the high-pressure shaft (9) via a gear unit (12) and a freewheel (13), wherein the freewheel (13) separates the connection between the output shaft (11) of the electrical machine (2) and the high-pressure shaft (9) in the presence of a torque flow from the high-pressure shaft (9) in the direction of the output shaft (11), wherein the gear unit (12) comprises a first spur gear stage (14), which has a first spur gear (15), which is connected in a rotationally fixed manner to the output shaft (11) and meshes with a second spur gear (16) of the first spur gear stage (14), which is connected in a rotationally fixed manner to a shaft (17), which is coupled to a first coupling half (18) of the freewheel (13), and wherein the gear unit (12) has a second spur gear stage (19) and a third spur gear stage (20), wherein a first spur gear (21) of the second spur gear stage (19) is arranged in a rotationally fixed manner on a shaft (22) that is connected in a rotationally fixed manner to a second coupling half (23) of the freewheel (13).

2. Device according to claim 1, characterised in that a second spur gear (24) of the second spur gear stage (19) is connected in a rotationally fixed manner via a shaft (25) to a first spur gear (26) of the third spur gear stage (20), which meshes with a second spur gear (27) of the third spur gear stage (20), which is operatively connected to the high-pressure shaft (9) in a rotationally fixed manner.

3. Device according to claim 1 or 2, characterised in that a further gearwheel (28), designed as a spur gear, of an auxiliary device gear mechanism (29) meshes with the first spur gear (21) of the second spur gear stage (19).

4. Device according to claim 3, characterised in that a spur gear (30) of the auxiliary device gear mechanism (29) is in engagement with the gearwheel (28) of the auxiliary device gear mechanism (29) and is arranged in a rotationally fixed manner on a shaft (31) of an auxiliary unit (32), via which the auxiliary unit (32) can be driven by the high-pressure shaft (9).

5. Device according to at least one of the preceding claims, characterised in that the gear unit (12) is arranged in the axial direction of the output shaft (11) between the electrical machine (2) and the compressor unit (5).

6. Aircraft with a device according to any of claims 1 to 5.