Drive system for a rotary-wing aircraft

Abstract

The invention relates to a drive system for a rotary-wing aircraft (10), comprising: a main drive unit (7) which is configured to generate a power with which a main rotor (1) of the rotary-wing aircraft (10) can be driven, a main transmission (6) which is configured to translate power generated by the main drive unit (7) into a torque acting on the main rotor (1), an additional or emergency drive unit (2) which is also configured to generate a power for driving the main rotor (1), wherein the additional or emergency drive unit (2) is designed to be connectable to the main transmission (6) via a switchable coupling unit (3). The invention also relates to a rotary-wing aircraft (10) comprising a drive system of this kind.

Description

[0001] Propulsion system for a rotary-wing aircraft

[0002] Technical field:

[0003] The invention relates to a drive system for a rotary-wing aircraft, in particular a helicopter, and to such a rotary-wing aircraft.

[0004] Technical background:

[0005] Rotary-wing aircraft, especially helicopters, can be subject to increased safety requirements in the event of a loss of engine power or a complete failure of the main engine. With single-engine helicopters, safe emergency landings can be achieved using autorotation, provided the pilot possesses exceptional skill. However, their use, particularly in densely populated or otherwise critical areas, is severely restricted in practice by regulations (e.g., European aviation law governing helicopter operations) because access to suitable landing sites is often difficult in such cases.

[0006] Many helicopter types are therefore often equipped with two essentially identical and powerful main engines, which are operated outside their optimal operating point. In an emergency, the remaining engine then powers the helicopter on its own.

[0007] When weighing economic efficiency against compliance with legal regulations, helicopter types equipped with, for example, only one main engine and an additional auxiliary engine for emergency use are also of interest. Thanks to improved energy storage capabilities in recent years, auxiliary drive systems based on electric motors are increasingly becoming viable options. US Patent 2019 / 0352001 A1 describes a propulsion system for a helicopter with only one engine. For use in emergency situations, an auxiliary drive unit is provided, which is physically integrated into a turboshaft main engine and forms a single unit with it. The auxiliary engine is mechanically connected to a rear drivetrain that extends between a freewheel clutch (for power transmission from the main engine to the drivetrain) and the tail rotor gearbox.Emergency propulsion of the entire drivetrain occurs when the rotation generated by the auxiliary propulsion motor is greater than either that generated by the main propulsion motor (e.g., in the event of engine failure) or that generated in the case of autorotation. The auxiliary propulsion motor may be, among other things, an electric drive.

[0008] US patent 2022 / 0388673 A1 describes the coupling of an electric motor to the main rotor of a helicopter via a reduction gearbox consisting of gears from the main gearbox.

[0009] US patent 2021 / 0229826 A1 describes a rotary-wing aircraft equipped with a propulsion system and an assistance system with an electric motor, which is used in emergencies. The electric motor is coupled to a secondary input of the main gearbox via a connecting module.

[0010] US patent 2020 / 0277072 A1 discloses a method for assisting the pilot of a single-engine rotary-wing aircraft during an autorotation phase of flight, wherein the rotary-wing aircraft comprises a hybrid propulsion system with a main engine and an electric motor. The operation of the main engine is monitored during flight to detect a power drop at the main rotor, and the electric motor is then controlled to supply additional power to the main rotor.

[0011] US 2020 / 0283139 A1 proposes a hybrid propulsion system in which, for example, a main drive unit is provided to operate the main rotor by an internal combustion engine or an electric motor, while the tail rotor is driven by a separate motor that is hydraulically, electrically, or pneumatically operated.

[0012] Patent specification US 10,759,280 B2 proposes various coupling options for an electric motor in a hybrid drive system, for example on the drive train coupled to the main machine, directly on the main gearbox or on the main rotor shaft extending from the main gearbox.

[0013] In the printed documents EP 4 015 377 A1 as well as

[0014] Hybrid drive systems are also described in WO 2021 / 151873 A1. EP 3 921 231 B1 proposes integrating an electric motor into at least one planetary gear of a planetary gearbox.

[0015] In most of the aforementioned proposals, the electric auxiliary drives are connected directly to the main gearbox or to the respective drive trains coupled to it. Mechanical separation of the main drive unit from the respective auxiliary drive is generally achieved via a mechanical freewheel clutch. However, the mechanical freewheel clutch requires lubrication, which increases maintenance, and allows torque transmission in only one direction. Furthermore, the numerous clamping elements within the freewheel clutch result in a large number of moving parts.

[0016] Furthermore, an auxiliary drive such as an electric motor, due to its direct connection to the main gearbox or drive train, is subject to the same high maintenance requirements as the other components of the drive system in order to ensure reliability, which increases the effort and costs of operation, even if the auxiliary drive is hardly ever used.

[0017] It is therefore a task to further improve existing drive system concepts and to reduce the costs and effort of general operation. Description of the invention:

[0018] According to aspects of the invention that address one or more of the aforementioned needs, a drive system for a rotary-wing aircraft, in particular for a helicopter, comprises a main drive unit configured to generate power with which a main rotor of the helicopter having several rotor blades can be driven, a main gearbox configured to translate the power generated by the main drive unit into a torque acting on the main rotor, and an auxiliary or emergency drive unit also configured to generate power for driving the main rotor, wherein the auxiliary or emergency drive unit is configured to be connectable to the main gearbox via a switchable clutch unit.

[0019] In a rotary-wing aircraft, the mechanical main gearbox transmits the engine's drive torque to the main rotor and, if applicable, a coupled tail rotor at the correct speed. The main gearbox is designed to deliver maximum torque. This can lead to particular problems if, for example, the main drive unit fails and additional torque is required.

[0020] If, for example, the main drive unit is still transmitting residual power while an auxiliary drive has already engaged, this can lead to an overload and permanent damage to the gearbox. The same can also apply in the case of stabilized autorotation flight. In this case, power is transmitted from the main rotor to the main gearbox, into which the engaged auxiliary drive now also feeds power, which can thus lead to an overload.

[0021] This problem is solved by the switchable clutch unit provided according to the invention. Unlike a freewheel clutch, which only operates in one direction of rotation and is therefore neither controllable nor switchable, such a switchable clutch unit can be selectively controlled and switched externally, depending on the situation. The switchable clutch unit allows the auxiliary or emergency drive unit provided for in the aforementioned aspects to be connected to the main transmission in a controlled manner in such cases.

[0022] In particular, the onset of torque transmission from the auxiliary or emergency drive unit can be selectively controlled. For example, the (not necessarily instantaneous) switching process of the clutch unit can be performed depending on the current load of the main gearbox. According to exemplary embodiments, a sensor and / or computer network can be used for this purpose, with which current rotational speeds in the main rotor, the main gearbox, and the drive trains are recorded, and the respective torques are calculated and compared with critical values. A further exemplary embodiment, described below, provides an auxiliary or emergency drive control unit, which can then control the switching process of the switchable clutch unit and, in coordination with the control system, also manage the power generation in the auxiliary or emergency drive unit.

[0023] Thus, a switchable clutch enables a seamless transition from a main drive via the main drive unit to an auxiliary drive via the additional or emergency drive unit, without exceeding critical torque limits. According to the invention, this applies not only to emergencies in the event of failure or power loss of the main drive unit, but also to purely auxiliary drive via the additional or emergency drive unit, since in such a case the same problems of excessive torque at the time of engagement exist. The same applies in the case of a power reversal, for example, if the additional or emergency drive unit is an electric motor that is temporarily operated as an electric generator to charge a battery module.

[0024] Additionally, the proposed solution allows for a controllable, mechanical separation of the auxiliary or emergency propulsion unit from the main gearbox and the main propulsion unit during normal flight operations. This decouples the auxiliary or emergency propulsion unit from these components, preventing any malfunctions in this area from directly affecting the main gearbox. As a result, maintenance intervals are somewhat shorter, which can reduce operating costs and effort.

[0025] The main propulsion unit can be any type of engine, for example, a thermodynamic engine, in particular a shaft turbine, e.g., with a gas generator and power turbine, or a piston engine. Other types, including electric motors, are also possible. If the rotary-wing aircraft is an autogyro, any type of traction or pusher engine can be provided. An implementation of two main propulsion units in the rotary-wing aircraft is also fundamentally encompassed by aspects of the invention.

[0026] The main rotor of the rotary-wing aircraft can be one with any number of rotor blades. The implementation of twin rotors can also be included within the scope of the invention. Optionally, a tail rotor gearbox can also be coupled, but this is not essential for the implementation of the invention.

[0027] The switchable clutch unit comprises the actual clutch and control electronics. It replaces, with significant advantages, the freewheel clutch, which was previously the only coupling available for the auxiliary or emergency drive unit, thereby eliminating the aforementioned disadvantages of the freewheel clutch. The switchable clutch unit is designed to connect or disconnect the auxiliary or emergency drive unit from the main gearbox. The connection to the main gearbox can be direct (via an input of the main gearbox) or indirect, via a drive train that is rigidly coupled to the main gearbox. A connection to the main gearbox, for example via a coupling to the rotor mast, is also possible.

[0028] The invention is not limited to specific types of switchable clutches.

[0029] Examples include the multi-plate clutch, the pole friction clutch, the magnetic clutch, and the magnetic powder clutch. Of these, the pole friction clutch may be the most preferred because it is particularly suitable for the initially very high differential speeds. The pole friction clutch operates in both dry and wet running conditions. With this type, engagement is triggered by an electric current and a resulting magnetic field, and torque transmission occurs through friction.

[0030] Alternatively, the aforementioned multi-plate clutch is also possible. It also operates in dry or wet running conditions. Here, the release lever for generating the contact pressure is triggered electronically, while the power transmission occurs via an electromagnet. The torque is transmitted purely mechanically through friction.

[0031] Furthermore, the aforementioned magnetic coupling can also be used. The torque is transmitted solely via a magnetic field, making this type of coupling completely wear-free. In the case of the magnetic powder coupling, the torque is transmitted via stiffening magnetic powder particles. Activation occurs through current flow, making variable torque particularly easy to achieve. Other switchable or controllable coupling types that enable a controlled coupling process are also conceivable.

[0032] The terms "switchable" and "controllable," referring to the clutch, are used synonymously in this application. This implies that the clutch can be selectively actuated externally to establish or disconnect a connection between the auxiliary or emergency drive unit and the main transmission, and that the clutching process itself can be controlled, i.e., the degree of torque transmission depending on the (in practice, potentially very short) time, e.g., through friction, etc., depending on the clutch type.

[0033] In a preferred embodiment, the auxiliary or emergency drive unit comprises an electric motor. This motor can preferably be designed and dimensioned such that a main rotor and / or tail rotor of a rotary-wing aircraft, in particular a helicopter, can be driven autonomously and without an additional drive. For the purposes of the present invention, an autonomous electric drive is understood to be one that provides a mechanical power output of preferably at least 80 kW, more preferably 100 kW to 700 kW, even more preferably 300 kW to 400 kW, and most preferably around 600 kW. The electric motor can be a synchronous motor, but the invention is not fundamentally limited to specific types of motors.

[0034] Electric motors have high torque, low wear and a very low latency time to deliver power, so control in coordination with the clutch process is particularly advantageous.

[0035] In principle, multiple electric motors can also be provided.

[0036] According to a further development, a first battery module is provided, which is configured to supply the electric motor of the auxiliary or emergency propulsion unit with electrical energy. Battery types with high power density are preferred here. According to specific embodiments, the first battery module serves to supply the electric motor with energy in an emergency, e.g., in the event of engine failure or power loss. For this purpose, the storage capacity of the first battery module is sufficient at least to achieve a flight range appropriate to the circumstances in order to reach a suitable landing site and, if necessary in conjunction with autorotation, to enable a single safe landing.

[0037] One embodiment, which includes the aforementioned types of clutches, provides that the switchable clutch unit is electromechanically and / or electromagnetically switchable in order to selectively connect or disconnect the auxiliary or emergency drive unit or the electric motor from the main gearbox.

[0038] According to further training, the switchable clutch unit is designed to engage and disengage an electric motor's drive shaft with an auxiliary drive train. This auxiliary drive train is connected to an input of the main gearbox. The power generated by the main drive unit can be supplied to the main gearbox via a main drive train. A special feature here is that the main drive train is connected to the same input of the main gearbox as the auxiliary drive train. This aspect offers a particular advantage because the entire design becomes especially simple and space-saving. The auxiliary or emergency drive unit with its clutch can thus be easily positioned opposite the main drive unit. The input of the main gearbox can, for example, be a sun gear that engages with a planetary gear set of the main gearbox.It has been found that, in practice, the described position in helicopters, for example, offers unused installation space above the passenger cabin (upper part of the fuselage), which is now being put to good use. Existing frames in this area often already possess the necessary load-bearing capacity to mount the electric motor.

[0039] Another aspect concerns an auxiliary or emergency drive control unit mentioned above. This unit is designed, depending on an activation criterion, to operate the electric motor and to engage the switchable clutch unit in order to connect or disconnect the electric motor from the main gearbox.

[0040] According to a first embodiment of this aspect, the auxiliary or emergency drive control unit is connected to a drive sensor system to detect an actual or imminent failure of the main drive unit. It is configured to start the electric motor based on the detection result as an activation criterion and to engage the clutch unit to connect the electric motor to the main gearbox, so that the main rotor is driven by the electric motor in emergency operation.

[0041] For this purpose, the drive sensor system can include one or more sensors for detecting at least one of the following values:

[0042] (a) rotational speed of the rotor,

[0043] (b) rotational speed of a gas generator of the main propulsion unit,

[0044] (c) Rotational speed of a power turbine of the main drive unit, etc. From these components, the auxiliary or emergency drive control unit, as described above, can not only detect the emergency situation, such as the power loss of the main drive, but also calculate and monitor the ongoing torque ratios during the subsequent shifting or control of the switchable clutch unit. The clutch operation can thus be dynamically adjusted depending on a currently detected and calculated torque in comparison with a predefined critical torque.

[0045] This control system is not only possible in emergency operation but also in generator mode. For example, a second battery module can be provided, configured to supply the electric motor of the auxiliary or emergency drive unit with electrical energy. The auxiliary or emergency drive control unit is connected to battery sensors to detect a low battery charge level in the first and / or second battery module. Furthermore, depending on the detection result, it is configured to activate the clutch unit, connecting the electric motor to the main gearbox and operating it as a generator to charge the second battery module with a portion of the main drive unit's power converted into electrical energy.

[0046] Unlike the first battery module, which cannot be recharged during flight operations, the second battery module can be recharged during flight. Therefore, the first battery module, located in a secure environment, is solely for emergency operation and thus meets the increased safety requirements. The second battery module, on the other hand, can be used to support ongoing flight operations (hereinafter referred to as auxiliary operation). However, it does not have to meet the very high safety requirements and therefore requires less maintenance, as it is not critical to flight operations in the same way.

[0047] Accordingly, another embodiment provides for the additional or

[0048] To connect an emergency drive control unit to a pilot control unit, wherein the pilot control unit has an input device and is configured to generate an input signal, depending on an input from a pilot into the input device, and to transmit this signal to the auxiliary or emergency drive control unit. The auxiliary or emergency drive control unit is further configured to start the electric motor, depending on the transmitted input signal as an activation criterion, and to engage the clutch unit to connect the electric motor to the main gearbox, so that the main rotor is driven in auxiliary operation by power from the electric motor in addition to the power provided by the main drive unit.

[0049] The auxiliary or emergency drive control unit can be configured as described to operate the auxiliary motor using a power supply exclusively from the second battery module. The energy stored in the first battery module is reserved solely for emergencies; that is, the first battery module does not need to be connected to any electrical load other than the electric motor, the auxiliary or emergency drive control unit, and the corresponding battery sensors. Charging or replacing the battery only occurs during ground maintenance.

[0050] According to a further, non-restrictive, specific embodiment of the invention, already mentioned above, the main drive unit, the main gearbox, and the auxiliary or emergency drive unit can be arranged essentially along a longitudinal axis of the rotary-wing aircraft, with the auxiliary or emergency drive unit and the main drive unit being located on opposite sides of the main gearbox. In the intended flight direction of the rotary-wing aircraft, the auxiliary or emergency drive unit is preferably located in front of the main gearbox. This results in the advantages described above. However, mounting the engine and the clutch laterally on the main gearbox is also not fundamentally excluded.

[0051] The invention also relates to a rotary-wing aircraft, in particular a helicopter, comprising a propulsion system according to one of the preceding aspects, embodiments or examples, or further developments. The auxiliary or emergency propulsion unit can advantageously be arranged in a space above a payload or passenger compartment provided in a cabin, in particular above a passenger compartment.

[0052] Furthermore, the invention also relates to the use of the drive system in a rotary-wing aircraft, in particular a helicopter.

[0053] The features, advantages and benefits of the invention are described below, also with reference to exemplary embodiments and the drawings.

[0054] Short the

[0055] They show:

[0056] Fig. 1 shows a schematic representation of a rotary-wing aircraft or helicopter with a propulsion system according to an exemplary embodiment of the invention;

[0057] Fig. 2 is a system drawing of the drive system according to Fig. 1;

[0058] Fig. 3 shows a schematic representation of a control network that provides the auxiliary or emergency drive, with the auxiliary or emergency drive control unit shown in Fig. 2 as the central control unit;

[0059] Fig. 4 shows a schematic representation of a control system in emergency mode;

[0060] Fig. 5 as Fig. 4, but for auxiliary operation (Power Boost Mode);

[0061] Fig. 6 as Fig. 4 or 5, but for generator operation (Power Generator Mode): Fig. 7 a side view of the drive system (without main drive unit);

[0062] Fig. 8 shows a cross-section through the drive system (excluding the main drive unit).

[0063] Detailed description of preferred embodiments:

[0064] In the following description of preferred embodiments, it should be noted that the present disclosure of the various aspects is not limited to the details of the construction and arrangement of the components as illustrated in the following description and in the figures. All embodiments, including those not shown in the figures, can be implemented or carried out in practice in various ways. Furthermore, it should be noted that the language and terminology used here are employed solely for the purpose of concrete description and should not be interpreted restrictively by a person skilled in the art.Furthermore, in the following description, identical reference symbols in the figures denote identical or similar features or objects, so that in some cases a repeated detailed description of the same is omitted in order to preserve the compactness and clarity of the presentation.

[0065] Fig. 1 shows a rotary-wing aircraft 10, here a helicopter, with a propulsion system according to an embodiment of the present invention. The rotary-wing aircraft 10 has a main rotor 1, equipped, for example, with two rotor blades, and a tail rotor 99. The main rotor 1 and the tail rotor 99 are driven by a main drive unit 7. The main drive unit 7 is, for example, a shaft-driven power turbine with a gas generator and power turbine. To convert a high rotational speed of the power turbine, for example, 6800 rpm, into high torque, a reducing main gearbox 6 is provided. The main rotor 1 is then operated with high torque at a reduced rotational speed, for example, 350 rpm. Via a drive train 8, which connects the main gearbox 6 to a tail rotor gearbox 9, the tail rotor 99 is rotated in a coordinated manner.

[0066] The propulsion system of the helicopter shown in Figure 1 further comprises an auxiliary or emergency propulsion unit 2, which is in particular an electric motor 21, for example a synchronous motor. The auxiliary or emergency propulsion unit 2 is connected to a first battery module 4 and a second battery module 5, so that these can selectively provide electrical energy for the operation of the auxiliary or emergency propulsion unit 2. The auxiliary or emergency propulsion unit 2 can be connected to or disconnected from the main gearbox 6 via a switchable clutch unit 3 in order to implement various operating modes of the helicopter, which are described below with reference to Figures 4-6.

[0067] Figure 2 shows a schematic overview of the drive system from Figure 1 in greater detail. Power transmission from the main drive unit 7 occurs via a freewheel clutch 72, which disconnects the main drive unit 7 from the drive train 8 when the corresponding rotational speed, reduced by the intermediate gearbox 71, falls below that of the drive train 8. In normal operation, the drive torque is transmitted to the main gearbox 6, where the high torque for the main rotor 1 is generated.

[0068] On the other hand, Figure 2 shows that the provision of electrical energy from the battery modules 4 and 5, the operation of the auxiliary or emergency drive unit 2 (i.e., the electric motor) and the switchable clutch unit 3 is controlled or regulated by an auxiliary or emergency drive control unit 35.

[0069] A network associated with the auxiliary or emergency drive control unit 35 is shown in greater detail in Figure 3. In this embodiment, the auxiliary or emergency drive control unit 35 is connected to a comprehensive sensor array that allows for evaluation of the current state of the drive system. Dashed arrows indicate input from sensors 11, 74, and 75 of the drive system operating normally. Specifically, these are a speed sensor 11 for the main rotor, a speed sensor 74 for the power turbine, and a speed sensor 75 for the gas generator. The design of these sensors can be arbitrary. Such sensors are typically also present in conventional helicopters, so the intervention in the existing system required to implement the invention is minimal.Based on the rotational speeds supplied by sensors 11, 74 and 75, the auxiliary or emergency drive control unit 35 can assess the presence of a critical condition (activation criterion) by comparing them with predefined critical values.

[0070] In addition, the auxiliary or emergency drive control unit 35 can also perform a calculation of the torque acting in the individual components based on the transmitted rotational speeds and compare it with specified critical limit torques.

[0071] Furthermore, the auxiliary or emergency drive control unit 35 is connected to a sensor / actuator 22 for the electric motor 21, which, for example, detects its speed and / or phase and transmits this information to the auxiliary or emergency drive control unit 35, or controls the motor power, and to a sensor / actuator 31 for the clutch unit 3, which provides data on its switching state and position (bold arrows in Fig. 3) and engages the clutch unit 3. The transmitted data allows the auxiliary or emergency drive control unit 35 to determine the torque currently being transmitted from the electric motor 21 to the main gearbox 6. Control via the actuators enables precise control of the engine start and clutch engagement process.In this way, appropriate regulation of the transition from main operation (only the main drive unit supplies power) to emergency, auxiliary or generator operation can be carried out.

[0072] The implementation of emergency operation 200 is shown schematically in Figure 4.

[0073] Step 202 is performed as described above by the additional or

[0074] Emergency drive control unit 35 determines whether a power drop has occurred ("Y") and thus whether emergency operation must be initiated (evaluation of data from sensors 11, 74, or 75). In step 204, the auxiliary or emergency drive control unit 35 first starts the electric motor 21 and then, in step 206, activates the clutch unit 3 to establish a connection between the electric motor 21 and the main gearbox 6 (actuation of actuators 22 and 31). In step 208, the status with regard to the applied torques is checked (evaluation of data from sensors 11, 22, 31, 74, and / or 75). In step 210, the calculated torques are compared with limit torques, and in step 212, feedback is provided to adjust the operation of the electric motor 21 and the clutch unit 3 in a control loop.

[0075] After a safe landing, the connection between the electric motor 21 and the main gearbox 6 can be disconnected (clutch opened) to allow the main rotor 1 to spin freely.

[0076] The aforementioned auxiliary operation 300 is shown in Figure 5. The basic procedure is very similar to that of the emergency operation, i.e., the clutch operation is controlled in a control loop to monitor the torque. In step 302, the auxiliary operation 300 is activated via an input device of a pilot control unit 101 shown in Figure 3. More precisely, it is repeatedly checked whether the corresponding signal is present ("Y"). Before the auxiliary operation is actually carried out, a check is performed in step 303 to determine whether there is still sufficient stored energy in the second battery module 5 (see the battery sensor 51 connected to the auxiliary or emergency drive control unit 35 in Figure 3) to carry out the auxiliary operation.If this is the case (“Y”), then in steps 304-312 the electric motor 21 and the clutch unit 3 are controlled in a manner analogous to Figure 4 in order to prevent damage caused by excessive torque.

[0077] The generator operation 400, also mentioned above, is shown in Figure 6. The event initiating generator operation 400 is when the state of charge of the second battery module 5 falls below a predetermined value. The currently recorded values ​​are regularly read from the battery sensor 51 (see Figure 3) by the auxiliary or emergency drive control unit 35 and compared with the predetermined limit value (step 401). In step 402, it is checked whether there is a power loss or failure of the main drive unit. In this case, it must be ensured that the electric motor 21 of the auxiliary or emergency drive unit is quickly available for transmitting drive torque. If this is not the case, in step 406 the clutch unit 3 is first actuated, followed by the electric motor 21.The auxiliary or emergency drive unit 2 is switched to generator mode to charge the second battery module 5. The coupling process is checked for excessive torque in the control loop analogous to Figure 4 or 5.

[0078] It should be noted that the auxiliary or emergency drive control unit 35 can also check the battery charge level of the first battery module 4 by means of the corresponding battery sensor 41, as shown in Figure 3.

[0079] Figure 7 shows a side view of the main gearbox 6 with rotor mast 66 and the auxiliary or emergency drive unit 2 connected to the main gearbox 6. Figure 8 shows the corresponding cross-section. The electric motor 21 has a motor shaft 32 which can be used with an auxiliary drive train 33 of the main gearbox 6 via the switchable clutch unit 3. The cross-section in Figure 8 shows that the auxiliary drive train 33 and the main drive train 8 engage at the same input in the main gearbox 6, which is formed by the sun gear 63. For this purpose, the auxiliary drive train 33 has a toothed section 34 and the main drive train 8 has a toothed section 81. The sun gear 63, in turn, interacts with a first stage 64 of a planetary gear set provided in the main gearbox 6.A second stage 65 of the planetary gear unit leads to a further reduction in the gear ratio and an increase in the torque, which is then transmitted to the rotor mast 66 via elements not shown in detail but known to those skilled in the art. An exemplary design of an implementable main gear unit 6, which does not limit the present invention, is disclosed, for example, in EP 3 323 718 A1. Other main gear unit designs are also possible.

[0080] The embodiments described above relate to a helicopter. However, the principles of the invention can be applied equally and analogously to other rotary-wing aircraft such as autogyros or quadcopters, etc.

[0081] List of

[0082] 1 main rotor

[0083] 11 Speed ​​sensor for main rotor

[0084] 2 Additional or emergency drive unit

[0085] 21 electric motor

[0086] 22 Sensor / actuator for electric motor (speed and / or phase position)

[0087] 3 switchable clutch units

[0088] 31 Sensor / actuator for clutch unit (switching state and position)

[0089] 32 Motor shaft (electric motor)

[0090] 33 Auxiliary drive train

[0091] 34 teeth, bevel gear

[0092] 35 Auxiliary or emergency drive control unit

[0093] 4. First battery module, not rechargeable during flight

[0094] 41 Sensor for first battery module (state of charge, temperature, voltage, etc.)

[0095] 5. Second battery module, rechargeable during flight

[0096] 51 Sensor for second battery module (state of charge, temperature, voltage, etc.)

[0097] 6 main gearboxes

[0098] 63 Entrance, sun wheel

[0099] 64 planetary gears, 1st stage

[0100] 65 planetary gear, 2nd stage

[0101] 66 Rotor mast

[0102] 7 Main drive unit

[0103] 71 Intermediate gears

[0104] 72 Freewheel clutch

[0105] 74 Speed ​​sensor for power turbine

[0106] 75 Speed ​​sensor for gas generator

[0107] 8 Main drivetrain

[0108] 81 Toothing, bevel gear

[0109] 9 tail rotor gearbox

[0110] 99 Tail rotor

[0111] 10 rotary-wing aircraft, helicopters

[0112] 101 Pilot control, with input device Emergency operation (start) Auxiliary operation (start) Generator operation (start)

Claims

Claims:

1. Drive system for a rotary-wing aircraft (10), comprising: a main drive unit (7) configured to generate power capable of driving a multi-bladed main rotor (1) of the rotary-wing aircraft (10), a main gearbox (6) configured to convert the power generated by the main drive unit (7) into torque acting on the main rotor (1), an auxiliary or emergency drive unit (2) also configured to generate power for driving the main rotor (1), wherein the auxiliary or emergency drive unit (2) is configured to be connectable to the main gearbox (6) via a switchable clutch unit (3).

2. Drive system according to claim 1, wherein the auxiliary or emergency drive unit (2) comprises an electric motor (21), and wherein the main drive unit (7) preferably comprises a thermodynamic power engine.

3. Drive system according to claim 2, further comprising: a first battery module (4) which is configured to supply the electric motor (21) of the auxiliary or emergency drive unit (2) with electrical energy.

4. Drive system according to claim 3, wherein the switchable clutch unit (3) is electromechanically and / or electromagnetically switchable to selectively connect or disconnect the auxiliary or emergency drive unit (2) or the electric motor (21) to the main gearbox (6).

5. Drive system according to one of claims 3 to 4, wherein the switchable clutch unit (3) is configured to couple and uncouple a drive shaft (32) of the electric motor (21) with an auxiliary drive train (33), the auxiliary drive train (33) is connected to an input of the main gearbox (6), the power generated by the main drive unit (7) is supplied to the main gearbox (6) via a main drive train (8), and the main drive train (8) is connected to the same input (63) of the main gearbox (6) as the auxiliary drive train (33).

6. Drive system according to claim 5, wherein the input (63) of the main gear (6) is formed by a sun gear which is operatively related to a planetary gear (64, 65).

7. Drive system according to one of claims 3 to 6, further comprising: an auxiliary or emergency drive control unit (35) which is configured to actuate the electric motor (21) depending on an activation criterion and to switch the switchable clutch unit (3) in order to connect the electric motor (21) to the main gearbox (6) or to disconnect it from it.

8. Drive system (10) according to claim 7, wherein the auxiliary or emergency drive control unit (35) is connected to a drive sensor system (22, 31, 11, 74, 75) to detect an actual or imminent failure of the main drive unit (7) and is configured to start the electric motor (21) depending on the detection result as an activation criterion and to switch the coupling unit (3) to connect the electric motor (21) to the main gearbox (6) so that the main rotor (1) is driven in an emergency operation (200) with the power provided by the electric motor (21).

9. Drive system according to claim 8, wherein the drive sensor system (22, 31, 11, 74, 75) comprises one or more sensors for detecting at least one of the following: (a) rotational speed of the rotor, (b) speed of the gas generator, (c) Speed ​​of the power turbine, 10. Drive system according to one of claims 7 to 9, further comprising a second battery module (5) which is configured to supply the electric motor (21) of the auxiliary or emergency drive unit (2) with electrical energy, wherein the auxiliary or emergency drive control unit (35) is connected to a battery sensor (41, 51) to detect a low battery charge level in the first and / or the second battery module (4, 5), and is configured, depending on the detection result as an activation criterion, to switch the clutch unit (3) to connect the electric motor (21) to the main gearbox (6) and to operate it in generator mode (400) as a generator in order to charge the second battery module (5) with a portion of the power of the main drive unit (7) converted into electrical power.

11. Propulsion system according to claim 10, wherein the first battery module (4) is configured to be non-rechargeable during flight operation; and the second battery module (5) is configured to be rechargeable during flight operation.

12. Drive system according to one of claims 7 to 11, wherein the auxiliary or emergency drive control unit (35) is connected to a pilot control unit (101), wherein the pilot control unit (101) has an input device and is configured to generate an input signal depending on an input from a pilot into the input device and to transmit it to the auxiliary or emergency drive control unit, wherein the auxiliary or emergency drive control unit is configured to start the electric motor depending on the transmitted input signal as an activation criterion and to switch the clutch unit (3) to connect the electric motor (21) to the main gearbox (6), so that the The main rotor (1 ) in an auxiliary operation (300) is driven additionally by power from the electric motor (21 ) in addition to the power from the main drive unit (7).

13. Drive system (10) according to claim 12 with reference to one of claims 10 or 11, wherein the auxiliary or emergency drive control unit (2) is configured to carry out the auxiliary operation (300) by means of the electric motor (21) on the basis of an energy supply exclusively from the second battery module (5).

14. Drive system according to one of the preceding claims, wherein the first battery module (4) is not connected to any electrical consumer except for the electric motor (21) and the auxiliary or emergency drive control unit (35) and corresponding battery sensors.

15. Drive system according to one of the preceding claims, wherein the main drive unit (7), the main gearbox (6) and the auxiliary or emergency drive unit (2) are arranged substantially along a longitudinal axis of the rotary-wing aircraft (10), wherein the auxiliary or emergency drive unit (2) and the main drive unit (7) are arranged on opposite sides with respect to the main gearbox (6), wherein the auxiliary or emergency drive unit (2) is preferably arranged in front of the main gearbox (6) in the intended direction of flight of the rotary-wing aircraft (10).

16. Rotary-wing aircraft (10), in particular a helicopter, comprising a propulsion system according to one of the preceding claims, wherein the auxiliary or emergency propulsion unit (2) is arranged in a space above a payload compartment provided in a cabin, in particular above a passenger compartment.

17. Use of a propulsion system according to any one of claims 1 to 15 in a rotary-wing aircraft, in particular a helicopter.

Images