Propulsion device for aircraft

Abstract

The present invention enables reductions in size and weight of a hybrid propulsion system for aircraft.　A propulsion device for an aircraft according to the present invention comprises: an engine 30 that outputs rotational force; a propeller 20 that generates propulsion force; a motor 50 that outputs rotational force; an input shaft 41 that has a first cog (first gear) 44 and receives the rotational force output from the engine 30; an output shaft 42 that has a second cog (second gear) 45 and outputs rotational force to the propeller 20; and an intermediate shaft 43 that has a third cog (third gear) 46 and a fourth cog (fourth gear) 47. The first cog 44 and the third cog 46 mesh with each other, and the second cog 45 and the fourth cog 47 mesh with each other. The motor 50 is connected to the intermediate shaft 43, and the rotational force from the motor 50 is input to the intermediate shaft 43.

Description

Aircraft propulsion systems

[0001] The present invention relates to a propulsion device for aircraft in which an engine rotates a propeller or fan, and a motor, which is an electric motor, are combined to assist the propulsion force and generate electricity.

[0002] An aircraft generally includes a fuselage, wings, and a propulsion system that provides thrust. The propulsion system is mounted on a nacelle suspended from the wing. There are several types of propulsion systems depending on the size of the aircraft, but turboprop engines are often used for small passenger aircraft that can accommodate several dozen passengers.

[0003] In aircraft with turboprop engines as their propulsion system, the turbine output shaft must maintain high rotational speeds to maintain engine efficiency, while the propeller shaft rotational speed must be limited so that the blade tips do not exceed the speed of sound. To optimize the rotational speeds of the turbine and propeller, many turboprop engines use a reduction gear between the turbine output shaft and the propeller shaft.

[0004] Furthermore, from the viewpoint of reducing fuel consumption of aircraft engines and reducing CO2 emissions, there is an increasing demand for hybridization in which engine output is assisted by an electric motor.

[0005] As an example of a system for realizing hybrid propulsion of an aircraft, Patent Document 1 describes a propulsion system for an aircraft that includes a propulsion device, a turbomachine that is mechanically coupled to the propulsion device in a combustion operation mode and mechanically decoupled from the propulsion device in an electric operation mode, and an electric machine, where the electric machine is electrically connected to an electric power source so that the propulsion device is driven by the electric machine in the electric operation mode. In the example, a configuration using a pair of turbofan engines mounted under the wings and a hybrid engine mounted at the rear of the fuselage is described.

[0006] Japanese Patent Application Laid-Open No. 2019-51922

[0007] An aircraft's propulsion system must be installed in the limited space inside the nacelle, and the weight of the aircraft has a significant impact on the required power output and range, so a small and lightweight hybrid propulsion system is required.

[0008] An object of the present invention is to propose a new aircraft propulsion device that solves the above problems.

[0009] One embodiment of the present invention is configured as follows.

[0010] The vehicle comprises: an engine that outputs rotational force; a propeller that generates thrust; a motor that outputs rotational force; an input shaft having a first gear and inputting the rotational force output from the engine; an output shaft having a second gear and outputting the rotational force to the propeller; and an intermediate shaft having a third gear and a fourth gear, wherein the first gear and the third gear mesh together, and the second gear and the fourth gear mesh together, and the motor is connected to the intermediate shaft and inputs the rotational force from the motor to the intermediate shaft.

[0011] According to the present invention, it is possible to hybridize an aircraft propulsion system without increasing its size, thereby reducing energy consumption and CO2 emissions. Problems, configurations, and effects other than those described above will become clear from the description of the following embodiments.

[0012] FIG. 1 is a schematic top view of an aircraft equipped with a propulsion device according to the present invention. FIG. 2 is a schematic view showing the appearance of a propulsion device according to the present invention stored in a nacelle. FIG. 3 is a schematic view showing the configuration of a propulsion device according to a comparative example to the present invention. FIG. 4 is a schematic view showing the configuration of a propulsion device according to a first embodiment of the present invention. FIG. 5 is a schematic view showing the configuration of a reducer and a motor of a propulsion device according to a first embodiment of the present invention. FIG. 6 is a schematic view showing the appearance of a reducer and a motor of a propulsion device according to a first embodiment of the present invention. FIG. 7 is a schematic view showing the configuration of a reducer and a motor of a propulsion device according to a second embodiment of the present invention. FIG. 8 is a schematic view showing the appearance of a reducer and a motor of a propulsion device according to a second embodiment of the present invention. FIG. 9 is a schematic view showing the appearance of a reducer and a motor of a propulsion device according to a third embodiment of the present invention.

[0013] An embodiment of an aircraft propulsion system (hybrid propulsion system) according to the present invention will be described below with reference to the drawings. In the drawings used in this specification, identical or corresponding components are designated by the same or similar reference numerals, and repeated description of these components may be omitted.

[0014] 1 is a schematic top view of an aircraft 1 equipped with a propulsion system according to the present invention. The aircraft 1 has a propulsion system 10 using propellers below the wings. The propulsion system 10 is a hybrid propulsion system that combines an engine 30 and a motor 50.

[0015] Fig. 2 is a schematic diagram showing the appearance of the propulsion device 10 according to the present invention in a state where it is stored in the nacelle 12. Fig. 3 is a schematic diagram showing the configuration of a propulsion device 10' according to a comparative example to the present invention.

[0016] The comparative example in Figure 3 shows a propulsion device 10' that is not a hybrid configuration and operates using only a turbine engine as an output source. The propulsion device 10' compresses air taken in through an air intake 13 using a turbine engine 30 and burns it together with fuel, and the force generated by the expansion rotates a turbine. This rotational force is transmitted to the shaft of the propeller 20 via a reduction gear 40, and the rotation of the propeller 20 propels the aircraft 1.

[0017] First Embodiment A first embodiment of the propulsion device 10 according to the present invention will be described with reference to FIGS. 4 to 6. FIG.

[0018] The overall configuration of the propulsion device 10 will be described with reference to Figures 4 and 5. Figure 4 is a schematic diagram showing the configuration of the propulsion device 10 according to a first embodiment of the present invention. Figure 5 is a schematic diagram showing the configuration of the reducer and motor of the propulsion device 10 according to the first embodiment of the present invention. In Figures 4 and 5, the case of the reducer 40 is omitted in order to show the connection configuration between the shaft and gears.

[0019] The propulsion device 10 shown in Fig. 4 includes a propeller 20, an engine 30, a reduction gear 40, and a motor 50. The engine 30 is configured as a gas turbine engine, and the rotational force generated by the engine 30 and the motor 50, which is an electric motor, is mechanically connected to a propeller shaft 42, which is the rotational axis of the propeller 20, via the reduction gear 40.

[0020] Of these, the reducer 40 includes an engine shaft (input shaft) 41 which is the output shaft of the engine 30, a propeller shaft (output shaft) 42 which is the rotational shaft of the propeller 20, a first gear (first toothed wheel) 44 which is integral with the engine shaft 41 and has the same rotational axis, a second gear (second toothed wheel) 45 which is integral with the propeller shaft 42 and has the same rotational axis, an intermediate shaft 43, a third gear (third toothed wheel) 46 which is integral with the intermediate shaft 43 and has the same rotational axis and meshes with the first gear 44, a fourth gear (fourth toothed wheel) 47 which is integral with the intermediate shaft 43 and has the same rotational axis and meshes with the second gear 45, etc. The intermediate shaft 43 is a shaft disposed between the engine shaft 41 and the propeller shaft 42 in a transmission path of rotational force from the engine shaft 41 to the propeller shaft 42.

[0021] Here, "having the same rotation axis" or "arranged coaxially" means that the central axis of rotation is the same, but does not necessarily mean that the rotation axis is made of the same member. For example, the engine shaft 41 and the rotation axis of the first gear 44 may be made of different members, and the central axis of the engine shaft 41 and the central axis of the rotation axis of the first gear 44 may be configured to coincide. Note that by making the engine shaft 41 and the rotation axis of the first gear 44 out of the same member, the number of parts can be reduced.

[0022] The number of teeth N1 of the first gear 44 and the number of teeth N3 of the third gear 46 have the relationship N1 < N3, and the number of teeth N2 of the second gear 45 and the number of teeth N4 of the fourth gear 47 have the relationship N2 < N4.

[0023] With the above configuration, the rotation of the output of the engine 30 is reduced in two stages and transmitted to the propeller 20. In an aircraft using a turboprop engine as its propulsion system, the turbine output shaft must be maintained at a high rotation speed to maintain engine efficiency. On the other hand, the rotation speed of the propeller shaft must be limited to a relatively low rotation speed so that the blade tips do not exceed the speed of sound. For these reasons, the structure of the speed reducer 40 described above can be said to be suitable for an aircraft in which the optimal rotation speed ratio between the engine shaft 41 and the propeller shaft 42 is large. The rotation speed ratio between the engine shaft 41 and the propeller shaft 42 is, for example, approximately 15:1.

[0024] Therefore, in this embodiment, the rotation speed Ri of the engine shaft 41, the rotation speed Ro of the propeller shaft 42, and the rotation speed Rm of the intermediate shaft 43 are set to have the relationship Ri>Rm>Ro.

[0025] 4 and 5, by connecting the rotating shaft of the motor 50 to the intermediate shaft 43, the output of the motor 50 is transmitted to the rotation of the propeller 20. With this configuration, it is not necessary to add an additional rotating shaft as a result of hybridizing the propulsion unit 10', and it is possible to minimize increases in size and weight of the propulsion unit 10. Furthermore, in designing the motor 50, it is relatively easy to design a motor that is suitable for a rotation speed intermediate between the high rotation speed of the engine shaft 41 (for example, approximately 20,000 rpm) and the low rotation speed of the propeller shaft 42 (for example, approximately 1,200 rpm) (for example, approximately 5,000 rpm).

[0026] The engine shaft 41, which is the rotation shaft of the engine (first power source) 30, and the intermediate shaft 43, which is the rotation shaft of the motor (second power source) 50, may be configured to be able to separate the power sources 30, 50 from the shaft on the reducer side by providing clutches 71, 72 between the power sources 30, 50 and the gears 44, 46. The clutch 71 is provided on the engine shaft 41 and connects and disconnects the engine (first power source) 30 from the engine shaft 41 on the reducer 40 side. The clutch 72 is provided on the intermediate shaft 43 and connects and disconnects the motor (second power source) 50 from the intermediate shaft 43 on the reducer 40 side.

[0027] That is, the rotating shaft of the motor 50 and the intermediate shaft 43 are connected via a clutch 72, and by operating the clutch 72 in accordance with the operating state, it is possible to control the connection and disconnection between the rotating shaft of the motor 50 and the intermediate shaft 43. Furthermore, the rotating shaft of the engine 30 and the engine shaft (input shaft) 41 are connected via a clutch 71, and by operating the clutch 71 in accordance with the operating state, it is possible to control the connection and disconnection between the rotating shaft of the engine 30 and the engine shaft 41.

[0028] In this case, only the output of the engine 30 may drive the propeller 20 during certain operating modes of the propulsion device 10, and only the output of the motor 50 may drive the propeller 20 during other operating modes. Alternatively, the outputs of both the engine 30 and the motor 50 may simultaneously drive the propeller 20. The motor 50 may also operate as a generator, converting rotational force into electrical power and extracting it. The extracted electrical power is supplied to the outside.

[0029] The motor 50 assists the engine 30 in situations where higher output than normal is required, such as during takeoff or climb, or when an abnormality occurs in one of the propulsion systems of a twin-engine aircraft. When propulsion with relatively low output is possible, such as during cruising, the propeller 20 can be operated using the output of the motor 50 alone to drive the aircraft. Alternatively, the motor 50 can be operated as a generator, allowing part of the output of the engine 30 to be used for generating electricity. Furthermore, when rotation of the propeller 20 is not required, such as during gliding, the motor 50 can be appropriately controlled to fix the rotation of the propeller 20.

[0030] 6 is a schematic diagram showing the appearance of the reducer 40 and motor 50 of the propulsion device 10 according to the first embodiment of the present invention. In this embodiment, the reducer 40 is housed in a reducer case 48, and a housing 51 of the motor 50 and a stator that corresponds to the outer periphery of the motor are mechanically connected to the outer wall of the reducer case 48. In other words, the reducer 40 is disposed inside the reducer case 48, and the stator of the motor 50 is fixed to the reducer case 48. Here, "fixing the stator of the motor 50 to the reducer case 48" includes not only cases where the stator is directly fixed to the reducer case 48, but also cases where the stator is indirectly fixed to the reducer case 48 via another member or component.

[0031] Meanwhile, the rotor, which contacts the inner periphery of the motor, is disposed coaxially with the intermediate shaft 43. That is, the rotor of the motor 50 is disposed so that its central axis of rotation overlaps with that of the intermediate shaft 43, and is connected to the intermediate shaft 43. In consideration of ease of maintenance, such as replacement or repair of the motor 50, the reducer case 48 and the housing 51 of the motor 50 are configured to be separate and separable.

[0032] The propulsion device 10 is provided with a battery (not shown) for driving the motor 50 and an inverter 60. For example, the battery may be mounted on the airframe outside the nacelle 12 and supply power to the motor 50 via wiring. The inverter 60 may be mounted on the outer wall of the reducer case 48, for example. In this case, the inverter 60 is preferably mounted on the outer wall of the reducer case 48 near the motor 50. This allows the hybridization of the propulsion device to be achieved without significantly changing the configuration of the propulsion device. Furthermore, for example, if the motor 50 is disposed in the lower part of the reducer case 48, the inverter 60 is preferably mounted on the outer wall of the lower part of the reducer case 48. This allows the motor 50 and the inverter 60 to be closer to each other, thereby shortening the length of the electrical wiring between them.

[0033] In this embodiment, a configuration is disclosed in which the motor 50 is attached to the surface of the reducer case 48 on the propeller 20 side (propeller shaft 42 side), but this configuration is not limited to this and the motor 50 may also be attached to the surface on the engine 30 side (engine shaft 41 side).

[0034] In this embodiment, the description is based on the premise that the reducer 40 performs two-stage reduction between the engine shaft 41 and the propeller shaft 42, but three or more stages of reduction may be performed. In this case, a plurality of rotating shafts, each having two gears, mesh between the first gear 44 and the second gear 45, and the motor 50 is connected to one of the plurality of rotating shafts, and the rotational force from the motor 50 is input to the connected rotating shaft.

[0035] Second Embodiment Next, a second embodiment of the propulsion device 10 according to the present invention will be described with reference to Figures 7 and 8. Figure 7 is a schematic diagram showing the configuration of the reducer 40 and motor 30 of the propulsion device 10 according to the second embodiment of the present invention. Figure 8 is a schematic diagram showing the appearance of the reducer 40 and motor 30 of the propulsion device 10 according to the second embodiment of the present invention. In Figure 7, the case of the reducer 40 is omitted in order to show the connection configuration between the shaft and gears.

[0036] The reducer 40 of the propulsion unit 10 of this embodiment differs from the propulsion unit 10 of the first embodiment in that two intermediate shafts 43a, 43b that transmit rotation from the engine shaft 41 to the propeller shaft 42 are arranged in parallel, and the rotation shafts of two motors 50a, 50b are connected to the two intermediate shafts 43a, 43b, respectively. Other configurations are the same as those of the propulsion unit 10 of the first embodiment.

[0037] On one intermediate shaft 43a, a third gear 46a and a fourth gear 47a are integrally formed with the same rotation axis, and the first gear 44 meshes with the third gear 46a, and the second gear 45 meshes with the fourth gear 47a. On the other intermediate shaft 43b, a third gear 46b and a fourth gear 47b are integrally formed with the same rotation axis, and the first gear 44 meshes with the third gear 46b, and the second gear 45 meshes with the fourth gear 47b.

[0038] Although not shown in FIG. 7, similarly to the first embodiment, it is preferable to provide a clutch 71 on the engine shaft 41 and a clutch 72 on each of the intermediate shafts 43a and 43b.

[0039] 8, the reducer 40 is disposed within a reducer case 48, the housings 51 a, 51 b and stators of the two motors 50 a, 50 b are mechanically connected to the outer wall of the reducer case 48, and the rotors that contact the inner periphery of the motors are disposed coaxially with the two intermediate shafts 43 a, 43 b. In consideration of ease of maintenance, such as replacement or repair of the motors 50 a, 50 b, the reducer case 48 and the housings of the motors 50 a, 50 b are configured to be separate and separable.

[0040] The electric hybrid propulsion device 10 of this embodiment can use the output of the two motors 50a, 50b to assist the engine output, which allows the motor output per motor to be reduced, making it possible to realize a more compact electric hybrid propulsion device. Furthermore, by providing two parallel intermediate shafts, the load on the gears and shafts is reduced, which is effective in terms of reliability and component life. Furthermore, if a problem occurs with one of the motors 50a, 50b, the other motor can continue to assist, providing a redundancy effect.

[0041] Third Embodiment Next, a third embodiment of the propulsion device 10 according to the present invention will be described with reference to Fig. 9. Fig. 9 is a schematic diagram showing the configuration of the reducer 40 and the motor 50 of the propulsion device 10 according to the third embodiment of the present invention.

[0042] The propulsion device 10 of this embodiment differs from the propulsion devices 10 of the first and second embodiments described above in that a motor 50 is built into a third gear 46 formed integrally with an intermediate shaft 43 that transmits rotation from an engine shaft 41 to a propeller shaft 42. Other configurations can be configured in the same way as the propulsion device 10 of the first or second embodiment.

[0043] The motor 50 of this embodiment has an outer rotor structure in which the inner periphery is a stator 52 and the outer periphery is a rotor 53, the rotor 52 being integral with the third gear 46, and the stator 52 being disposed on the inner periphery (inner periphery side) of the third gear 46 and fixed to, for example, the inner wall of the reducer case 48. In other words, the stator of the motor 50 is fixed to the reducer case 48. The rotation axis of the rotor 52 is coaxial with the intermediate shaft 43.

[0044] The reducer 40 is provided with a nozzle 81 that sprays oil and a pump 82 that supplies oil to the nozzle 81 in order to cool and lubricate the gears 44 to 47 inside the reducer case 48. In this case, the motor 50 is cooled by the oil sprayed inside the reducer case 48 to cool and lubricate the gears 44 to 47.

[0045] The propulsion device 10 of this embodiment can realize a smaller propulsion device by mounting the assist motor 50 inside the existing gear 46, compared to a configuration in which the motor 50 is mounted on the outside of the reducer case 48.

[0046] According to the propulsion system 10 of the present invention described above, it is possible to hybridize the aircraft propulsion system without increasing its size, thereby reducing energy consumption and CO2 emissions.

[0047] Propulsion devices (propulsion systems) that use turboprop engines often use an intermediate shaft to reduce speed using two-stage gears due to the difference in rotation speed between the engine and the propeller. However, according to embodiments of the present invention, a hybrid configuration is possible in which the output of a motor is connected without using any additional shafts or gears, making it easy to replace with a normal, non-hybrid propulsion device.

[0048] The aircraft propulsion device 10 according to the present invention described above has the following features: (1) An engine 30 that outputs a rotational force, a propeller 20 that generates a thrust force, a motor 50 that outputs a rotational force, an input shaft 41 having a first gear 44 and receiving the rotational force output from the engine 30, an output shaft 42 having a second gear 45 and outputting the rotational force to the propeller 20, and an intermediate shaft 43 having a third gear 46 and a fourth gear 47, wherein the first gear 44 and the third gear 46 mesh, and the second gear 45 and the fourth gear 47 mesh, and the motor 50 is connected to the intermediate shaft 43, and inputs the rotational force from the motor 50 to the intermediate shaft 43.

[0049] (2) The first gear 44, the second gear 45, the third gear 46, and the fourth gear 47 constitute the reducer 40, and there is a relationship of Ri>Rm>Ro among the rotation speed Ri of the input shaft 41, the rotation speed Rm of the intermediate shaft 43, and the rotation speed Ro of the output shaft 42.

[0050] (3) The reducer 40 is disposed inside the reducer case 48 , and the stator of the motor 50 is fixed to the reducer case 48 .

[0051] (4) The reducer 40 is arranged inside the reducer case 48, the motor 50 has an outer rotor type configuration, the rotor of the motor 50 is integral with the third gear 46, and the stator of the motor 50 is fixed to the reducer case 48.

[0052] (5) The motor 50 described in (4) is cooled by oil sprayed inside the reducer case 48 to cool and lubricate the gears.

[0053] (6) The rotating shaft of the motor 50 and the intermediate shaft 43 are connected via a clutch 72. By operating the clutch 72 according to the operating state, the connection and disconnection between the rotating shaft of the motor 50 and the intermediate shaft 43 can be controlled.

[0054] (7) Two or more intermediate shafts (43a, 43b) each having a third gear 46 and a fourth gear 47 are provided, and multiple power transmission paths from the input shaft 41 to the output shaft 42 are configured.

[0055] (8) The motor 50 operates as a generator, converting rotational force into electric power and supplying it to the outside.

[0056] (9) The inverter 60 that supplies power to drive the motor 50 is disposed on the outer wall of the reducer case 48 that houses the reducer 40 .

[0057] (10) A plurality of rotating shafts, each having two gears, are meshed between the first gear 44 and the second gear 45, and the motor 50 is connected to one of the rotating shafts, and the rotational force from the motor 50 is input to the connected rotating shaft.

[0058] The above has described in detail an embodiment of the hybrid propulsion device 10 according to the present invention using the drawings, but the specific configuration is not limited to this embodiment, and even if there are design changes, etc., within the scope that does not deviate from the gist of this disclosure, they are included in the present invention.

[0059] For example, the present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0060] 1...aircraft, 10...propulsion device (hybrid propulsion device), 12...nacelle, 13...air intake, 20...propeller, 30...engine, 40...reduction gear, 41...engine shaft (input shaft), 42...propeller shaft (output shaft), 43, 43a, 43b...intermediate shaft (intermediate shaft), 44...first gear (first gear), 45...second gear (second gear), 46, 46a, 46b...third gear (third gear), 47, 47a, 47b...fourth gear (fourth gear), 48...reduction gear case, 50, 50a, 50b...motor.

Claims

1. A propulsion device for an aircraft comprising: an engine that outputs rotational force; a propeller that generates thrust; a motor that outputs rotational force; an input shaft having a first gear and that inputs the rotational force output from the engine; an output shaft having a second gear and that outputs the rotational force to the propeller; and an intermediate shaft having a third gear and a fourth gear, wherein the first gear and the third gear mesh and the second gear and the fourth gear mesh, and the motor is connected to the intermediate shaft and inputs the rotational force from the motor to the intermediate shaft.

2. A propulsion device for an aircraft as described in claim 1, wherein the first gear, the second gear, the third gear, and the fourth gear form a reducer, and there is a relationship of Ri > Rm > Ro between the rotation speed Ri of the input shaft, the rotation speed Rm of the intermediate shaft, and the rotation speed Ro of the output shaft.

3. A propulsion device for an aircraft according to claim 2, wherein the reducer is disposed inside a reducer case, and the stator of the motor is fixed to the reducer case.

4. A propulsion device for aircraft as set forth in claim 2, wherein the reducer is disposed inside the reducer case, the motor is of an outer rotor type, the rotor of the motor is configured integrally with the third gear, and the stator of the motor is fixed to the reducer case.

5. A propulsion device for an aircraft according to claim 4, wherein the motor is cooled by oil sprayed inside the reducer case to cool and lubricate the gears.

6. A propulsion device for aircraft as described in claim 2, wherein the rotating shaft of the motor and the intermediate shaft are connected via a clutch, and the connection and disconnection of the rotating shaft of the motor and the intermediate shaft can be controlled by operating the clutch according to the operating state.

7. An aircraft propulsion device as claimed in claim 2, wherein two or more intermediate shafts each equipped with the third gear and the fourth gear are provided, and a plurality of power transmission paths are configured from the input shaft to the output shaft.

8. A propulsion device for an aircraft according to claim 2, wherein the motor operates as a generator, converting rotational force into electric power and supplying it to the outside.

9. A propulsion device for aircraft according to claim 2, wherein an inverter that supplies power to drive the motor is disposed on the outer wall of a reducer case that houses the reducer.

10. A propulsion device for aircraft as described in claim 1, wherein a plurality of rotating shafts, each having two gears, are meshed between the first gear and the second gear, and the motor is connected to one of the plurality of rotating shafts, and inputs rotational force from the motor to the connected rotating shaft.

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