Drive systems for rotary-wing aircraft

Abstract

The present invention relates to a drive system for a rotary-wing aircraft (10), which includes a main drive engine (7) configured to generate power capable of driving the main rotor (1) of the rotary-wing aircraft (10), a main reduction gear (6) provided to convert the power generated by the main drive engine (7) into torque acting on the main rotor (1), and an auxiliary / emergency drive engine (2) also configured to generate power for driving the main rotor (1), the auxiliary / emergency drive engine (2) being connectable to the main reduction gear (6) via a switchable coupling unit (3). The present invention also relates to a rotary-wing aircraft (10) equipped with such a drive system.

Description

Technical Field

[0001] The present invention relates to a rotary-wing aircraft, particularly a drive system for a helicopter, and to such a rotary-wing aircraft.

Background Art

[0002] Rotary-wing aircraft, particularly helicopters, may be subject to more stringent requirements regarding safety in case of a reduction in drive output or a complete failure of the main drive engine. In a single-engine helicopter, the pilot can use special flying techniques to perform a safe emergency landing in a well-known manner using autorotation. However, operations in densely populated areas and other critical areas are actually very restricted by regulations (e.g., European aviation law regarding helicopter operations) due to the difficulty of accessing a suitable landing site.

[0003] Therefore, many helicopters basically have two of the same high-performance main engines, which operate outside the optimal operating point. In an emergency, the helicopter is operated by only the remaining engine. Considering the balance between economy and compliance with legal regulations and rules, for example, a type of helicopter equipped with one main engine and an auxiliary engine for use in an emergency is also interesting. In recent years, due to the improvement of battery capacity, electric motor-based auxiliary propulsion systems have also attracted increasing attention.

[0004] Patent Document 1 describes a drive system for a helicopter equipped with only one engine. For use in emergencies, an auxiliary drive engine is provided, which is physically integrated with and attached to the turboshaft main engine. The auxiliary drive engine is mechanically connected to the rear drive system, which is located between the freewheel clutch (for power transmission from the main engine to the drive system) and the tail rotor reduction gear. If the rotation generated by the auxiliary drive engine is greater than the rotation generated by the main drive engine (for example, in the event of engine failure) or greater than the rotation in the case of autorotation, emergency drive is performed by the entire drive system. The auxiliary drive engine may, in particular, be based on electric drive.

[0005] Patent Document 2 describes connecting an electric motor to the main rotor of a helicopter via a reduction gear composed of gears in a main reduction gear.

[0006] Patent Document 3 describes a rotary-wing aircraft equipped with an engine and an auxiliary system comprising an electric motor for use in emergencies. The electric motor is connected to the secondary input of the main reduction gear via a connecting module.

[0007] Patent Document 4 discloses a method for assisting a pilot of a single-engine rotary-wing aircraft during the autorotation flight phase, which is equipped with a hybrid propulsion system comprising a main engine and an electric motor. During flight, the operation of the main engine is monitored to detect a decrease in main rotor output, and the electric motor is controlled to supply auxiliary output to the main rotor.

[0008] Patent Document 5 proposes, for example, a hybrid drive system in which the main drive engine for driving the main rotor is provided by an internal combustion engine or an electric motor, and the tail rotor is driven by another motor that operates hydraulically, electrically, or pneumatically.

[0009] Patent Document 6 proposes various methods for connecting electric motors in hybrid drive systems, such as connecting them to a drive system connected to the main engine, direct connection to the main reduction gear, or connection to the main rotor shaft extending from the main reduction gear.

[0010] Patent documents 7 and 8 also describe hybrid drive systems. Patent document 9 proposes incorporating an electric motor into at least one planetary gear of a planetary gear system. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] U.S. Patent Application Publication No. 2019 / 0352001 [Patent Document 2] U.S. Patent Application Publication No. 2022 / 0388673 [Patent Document 3] U.S. Patent Application Publication No. 2021 / 0229826 [Patent Document 4] U.S. Patent Application Publication No. 2020 / 0277072 Specification [Patent Document 5] U.S. Patent Application Publication No. 2020 / 0283139 [Patent Document 6] U.S. Patent No. 10,759,280 [Patent Document 7] European Patent Application Publication No. 4015377 [Patent Document 8] International Publication No. 2021 / 151873 [Patent Document 9] European Patent No. 3921231 [Overview of the project] [Problems that the invention aims to solve]

[0012] In most of the aforementioned proposals, the electric auxiliary drive engines are directly connected to the main reduction gear or each drive system connected to it. Mechanical separation of the main drive engine and each auxiliary drive engine is generally achieved by a mechanical freewheel clutch. However, mechanical freewheel clutches require lubrication, resulting in a high maintenance burden, and they can only transmit torque in one direction. Furthermore, freewheel clutches incorporate numerous clamping bodies, resulting in a large number of moving parts.

[0013] Furthermore, because auxiliary drive systems such as electric motors are directly connected to the main reduction gear and drive system, they are subject to high maintenance requirements to prevent failure, just like other components of the drive system. Therefore, even if the auxiliary drive systems are rarely used, operating costs and effort increase.

[0014] Therefore, the challenge lies in further improving the concept of existing drive systems and reducing the costs and effort involved in general operation. [Means for solving the problem]

[0015] According to an embodiment of the invention that addresses any of the above needs, a drive system for a rotary-wing aircraft, particularly a helicopter, includes a main drive engine configured to generate power capable of driving a main rotor having multiple rotor blades of a helicopter; a main reduction gear configured to convert the power generated by the main drive engine into torque acting on the main rotor; and an auxiliary / emergency drive engine similarly configured to generate power for driving the main rotor, the auxiliary / emergency drive engine being configured to be connectable to the main reduction gear via a switchable coupling unit.

[0016] The mechanical main reduction gear serves to transmit the drive torque from the engine to the main rotor and, if necessary, to a connected tail rotor at an appropriate rotational speed in a rotary-wing aircraft. The main reduction gear is designed to achieve maximum torque. This can cause special problems, for example, when the main drive engine fails and additional torque needs to be supplied.

[0017] For example, if residual power is transmitted from the main drive engine even though the auxiliary drive engine is operating, the reduction gear may be overloaded and permanent damage may occur. This is also the case for stabilized autorotation flight. In this case, power is transmitted from the main rotor to the main reduction gear, but since the auxiliary drive engine also supplies power, an overload may occur.

[0018] This problem is solved by the switchable coupling unit according to the invention. Different from a freewheel clutch that acts in only one direction and cannot be controlled or switched, such a switchable coupling unit can be intentionally controlled and switched externally according to the situation. With the switchable coupling unit, the auxiliary / emergency drive engine can be connected to the main drive engine in a controlled manner in such cases according to the above-described aspects.

[0019] In particular, the start of torque transmission from the auxiliary / emergency drive engine can be intentionally controlled. For example, the switching operation of the coupling unit (which is not necessarily instantaneous) can be carried out according to the current load of the main reduction gear. For this purpose, according to an embodiment, sensors and / or a calculation network for measuring the current rotational speeds in the main rotor, the main reduction gear, and the drive train, calculating the respective torques therefrom, and comparing them with threshold values can be utilized. According to another embodiment, the auxiliary / emergency drive control unit described below can control the switching operation of the switchable coupling unit based on this and, in conjunction with this control, can also control the power generation of the auxiliary / emergency drive engine.

[0020] As a result, with the switchable connection, it is possible to seamlessly shift from the main drive by the main drive engine to the auxiliary drive by the auxiliary / emergency drive engine without exceeding the limit torque. This invention is applicable not only to emergency situations such as failure or output reduction of the main drive engine, but also to cases of simple auxiliary drive by the auxiliary drive engine or the emergency drive engine. This is because the same problem of excessive torque generation during connection occurs in such cases as well. This is also the case for output reversal when the auxiliary / emergency drive engine is, for example, an electric motor that temporarily operates as a generator to charge the battery module.

[0021] Furthermore, with the solution proposed here, it is also possible to controllably and mechanically separate the auxiliary / emergency drive engine from the main reduction gear and the main drive engine during normal flight operations. As a result, the auxiliary / emergency drive engine is disconnected from these components, and a failure occurring in this part does not directly affect the main reduction gear. As a result, the requirements for maintenance intervals are slightly relaxed, and the operating costs and effort can be reduced.

[0022] The main drive engine can be any type of power machine, for example, a thermodynamic engine, particularly a shaft turbine equipped with a gas generator and a power turbine, or a piston engine, etc. However, other types, such as an electric motor, are also possible. When the rotary-wing aircraft is an autogyro, any type of traction engine or thrust engine can be adopted. Basically, the aspects of the present invention also include implementing two main drive engines in the rotary-wing aircraft.

[0023] The main rotor of the rotary-wing aircraft can use one equipped with any number of rotor blades. Also, the introduction of a dual rotor may be included in the aspects of the present invention. As an option, it is possible to connect the tail rotor reduction gear, but this is not essential for the implementation of the present invention.

[0024] The switchable coupling unit consists of an actual coupler and control electronics. It replaces the freewheel clutch, which was previously used as the sole coupling for auxiliary and emergency drive engines, and overcomes the aforementioned drawbacks due to its significant advantages. The switchable coupling unit is configured to connect or disconnect the auxiliary and emergency drive engine to the main reduction gear. Connection to the main reduction gear can be made directly (at the input of the main reduction gear) or indirectly via a drive system securely coupled to the main reduction gear. Connection to the main reduction gear is also possible via a coupler to the rotor mast, for example.

[0025] This invention is not limited to a specific type of switchable coupling unit. Examples include multi-plate clutches, polar friction clutches, magnetic clutches, and magnetic powder clutches. Of these, polar friction clutches are considered the most preferred because they are particularly well-suited to the very high differential rotational speeds at the initial stage. Polar friction clutches operate in either dry or wet operation. In this type, they are operated by the flow of electric current and the formation of a magnetic field, and torque is transmitted by frictional contact.

[0026] Alternatively, the aforementioned multi-plate clutch can also be used. This also functions in both dry and wet operation. In this case, the operating lever for generating contact pressure is electronically operated, and force transmission is carried out by an electromagnet. Torque is transmitted purely mechanically by frictional contact.

[0027] Furthermore, the aforementioned magnetic clutch can also be used. Since torque is transmitted solely by the magnetic field, this type of clutch is completely wear-free. In the case of a magnetic powder clutch, torque is transmitted through hardening magnetic powder particles. Operation is performed by the flow of electric current, and variable torque can be achieved particularly easily. However, other switchable or controllable coupling types that allow for controlled coupling operation are equally conceivable.

[0028] The terms “switchable” and “controllable” in relation to couplers are used synonymously in this application. This means that the coupler can be intentionally activated from the outside to connect or disconnect the auxiliary / emergency drive engine and the main reduction gear, and that the coupling operation itself, i.e., depending on the type of coupler, the degree of torque transmission can be controlled over time (which may actually be very short), for example by friction.

[0029] In preferred embodiments, the auxiliary / emergency drive engine includes an electric motor. It is further preferable that the main rotor and / or tail rotor of a rotary-wing aircraft, particularly a helicopter, be designed and dimensionally configured to be autonomously driven without additional drive engines. In this invention, autonomous electric drive engine means that a mechanical output of preferably at least 80 kW, more preferably 100 kW to 700 kW, even more preferably 300 kW to 400 kW, and particularly preferably about 600 kW is achievable. The electric motor may be a synchronous motor, but in principle, this invention is not limited to a particular type of motor.

[0030] Electric motors offer high torque, low wear, and extremely short latency to power generation, making them particularly advantageous for control in conjunction with coupling operations.

[0031] In principle, multiple electric motors can also be installed.

[0032] Further improvements involve the installation of a first battery module to supply power to the electric motor of the auxiliary / emergency drive system. Here, a high-power-density battery type is preferred. According to a particular embodiment, the first battery module is used to supply power to the electric motor in emergencies such as drive system failure or power reduction. For this purpose, the storage capacity of the first battery module is sufficient to ensure an appropriate flight distance depending on the situation, reach a suitable landing site, and enable a safe landing in combination with autorotation as needed.

[0033] In embodiments including the type of coupler described above, the switchable coupling unit is electromechanically and / or electromagnetically switchable to selectively connect or disconnect an auxiliary / emergency drive engine or electric motor to the main reduction gear.

[0034] Further improvements have resulted in a switchable coupling unit configured to connect and disconnect the electric motor's drive shaft to and from the auxiliary drive system. This auxiliary drive system is connected to the input of the main reduction gear. Power generated by the main drive engine is supplied to the main reduction gear via the main drive system.

[0035] A key feature in this design is that the main drive system is connected to the same main reduction gear input as the auxiliary drive system. This offers a special advantage in that the overall structure is particularly simple and space-saving. This allows the auxiliary / emergency drive engine and its coupling to be easily positioned on the opposite side of the main drive engine. The input gear of the main reduction gear can consist, for example, a sun gear that works in conjunction with the planetary gears of the main reduction gear. In helicopters, it has been demonstrated that unused installation space exists in the aforementioned location, for example, above the passenger cabin (above the cabin fuselage), and this space can be effectively utilized. The frame in this area often already possesses the necessary support capacity for installing electric motors.

[0036] Another aspect relates to the aforementioned auxiliary / emergency drive control unit. This unit is configured to operate an electric motor according to operating criteria and to switch a switchable coupling unit to connect or disconnect the electric motor from the main reduction gear.

[0037] According to the first embodiment of this pattern, the auxiliary / emergency drive control unit is connected to a drive sensor and detects a failure or impending failure of the main drive engine. In this case, depending on the detection result which serves as the operating criterion, the unit activates the electric motor, switches the coupling unit to connect the electric motor to the main reduction gear, and is set so that the main rotor is driven by the power of the electric motor in emergency mode.

[0038] For this purpose, the drive sensor may include one or more sensors for detecting at least one of the following values. (a) Rotor speed (b) Rotational speed of the gas generator of the main drive engine (c) Rotational speed of the power turbine of the main drive engine etc.

[0039] From these components, as mentioned above, the auxiliary / emergency drive control unit can not only detect emergencies such as a drop in output of the main drive engine, but also calculate or track the current torque state when the switchable coupling unit is switched or controlled next. Therefore, the coupling operation can be dynamically adjusted by comparing the currently detected and calculated torque with a predetermined critical torque.

[0040] This control is possible not only in emergency mode but also in generator mode. For example, a second battery module is provided, configured to supply power to the electric motor of the auxiliary / emergency drive engine, and the auxiliary / emergency drive control unit is connected to a battery sensor to detect when the battery charge levels of the first and / or second battery modules are low. Furthermore, depending on the detection result as the operating criterion, the coupling unit is operated to connect the electric motor to the main reduction gear and operate as a generator in generator mode, converting a portion of the output of the main drive engine into electrical output to charge the second battery module.

[0041] Unlike the first battery module, which cannot be charged during flight, the second battery module can be charged during flight. Therefore, the first battery module, which is in a safe environment, is designed to be used only in emergencies and, accordingly, meets higher safety requirements. On the other hand, the second battery module can be used to support modes during flight (hereinafter referred to as "auxiliary modes"), but since it is not as critical to flight operations, it does not need to meet extremely high safety requirements and, accordingly, requires less maintenance.

[0042] Therefore, in another embodiment, an auxiliary / emergency drive control unit is connected to a pilot control unit, which is equipped with an input device and configured to generate an input signal in response to input from the pilot to the input device and transmit it to the auxiliary / emergency drive control unit. The auxiliary / emergency drive control unit further operates an electric motor using the transmitted input signal as an operating reference, operates a coupling unit to connect the electric motor to the main reduction gear, and is configured so that the main rotor is driven auxiliaryly in auxiliary mode by the power of the electric motor in addition to the power from the main drive engine.

[0043] As described above, the auxiliary / emergency drive control unit can be configured to operate in an auxiliary mode using the electric motor based solely on energy supplied from the second battery module. The energy stored in the first battery module is used only in emergencies. In other words, the first battery module does not need to be connected to any electrical consuming equipment other than the electric motor, the auxiliary / emergency drive control unit, and the corresponding battery sensor. Battery charging or replacement is performed only during ground maintenance.

[0044] According to another non-limiting specific embodiment of this invention already suggested above, the main drive engine, main reduction gear, and auxiliary / emergency drive engine are basically arranged along the longitudinal axis of the rotorcraft, with the auxiliary / emergency drive engine and the main drive engine positioned opposite each other to the main reduction gear. The auxiliary / emergency drive engine is preferably positioned in front of the main reduction gear in a predetermined flight direction of the rotorcraft. This results in the aforementioned advantages. However, the placement of the motor and coupling to the side of the main reduction gear is not ruled out in principle.

[0045] The present invention also relates to rotary-wing aircraft, particularly helicopters, equipped with a drive system including any of the above-described embodiments, examples, or modifications. In this case, it is useful to position the auxiliary or emergency drive engine in a space above the cargo space or crew space, particularly the passenger space, within the cabin.

[0046] Furthermore, the present invention also relates to the use of drive systems in rotary-wing aircraft, particularly helicopters.

[0047] The features, usefulness, and advantages of the present invention will be described below based on examples with reference to the drawings. [Brief explanation of the drawing]

[0048] [Figure 1] A schematic diagram of a rotary-wing aircraft, i.e., a helicopter, equipped with a drive system according to an embodiment of the present invention. [Figure 2] A system diagram of the drive system shown in Figure 1. [Figure 3] Figure 2 shows a schematic diagram of the control network that enables auxiliary or emergency drive, with the auxiliary / emergency drive control unit acting as the central control unit. [Figure 4] A schematic diagram of the control system in Emergency Mode. [Figure 5] This is similar to Figure 4, but for the auxiliary mode (Power Boost Mode). [Figure 6]Similar to Figure 4 or Figure 5, but for Power Generator Mode. [Figure 7] Side view of the drive system (excluding the main drive engine). [Figure 8] Cross-sectional view of the drive system (excluding the main drive engine). [Modes for carrying out the invention]

[0049] In the following description of preferred embodiments, it should be noted that various aspects of the present disclosure are not limited to the details of configurations and component arrangements shown in the following description and drawings. All embodiments, including those not shown in the drawings, can be put into practical use or carried out in various ways. Furthermore, it should be noted that the expressions and terms used herein are for illustrative purposes only and should not be interpreted in a restrictive manner by those skilled in the art. In addition, in the following description, the same reference numerals in the figures may indicate the same or similar characteristics or objects, and in order to maintain the brevity and clarity of the description, repeated detailed descriptions of them may be omitted.

[0050] Figure 1 shows a rotary-wing aircraft 10, in this case a helicopter, equipped with a drive system according to an embodiment of the present invention. The rotary-wing aircraft 10 comprises a main rotor 1 with, for example, two rotor blades and a tail rotor 99. The main rotor 1 and tail rotor 99 are driven by a main drive engine 7. The main drive engine 7 is, for example, a shaft-output turbine equipped with a gas generator and a power turbine. A main reduction gear 6 is installed to reduce the rotational speed of the power turbine, e.g., 6800 rpm, to convert it into high torque. The main rotor 1 ultimately operates at a reduced rotational speed, e.g., 350 rpm, with high torque. The tail rotor 99 rotates in coordination with the main reduction gear 6 via a drive system 8 that connects the main reduction gear 6 to a tail rotor reduction gear 9.

[0051] The helicopter's drive system shown in Figure 1 further includes an auxiliary / emergency drive engine 2, which is in particular an electric motor 21, such as a synchronous motor. The auxiliary / emergency drive engine 2 is connected to a first battery module 4 and a second battery module 5, respectively, which allow for the selective supply of the electrical energy required for the operation of the auxiliary / emergency drive engine 2. The auxiliary / emergency drive engine 2 can be connected to or disconnected from the main reduction gear 6 by a switchable coupling unit 3, enabling various operating modes of the helicopter. These operating modes will be described later with reference to Figures 4 to 6.

[0052] Figure 2 is a schematic diagram showing the drive system of Figure 1 in detail. Power is transmitted from the main drive engine 7 by a freewheel clutch 72, which disconnects the main drive engine 7 from the drive system 8 when the rotational speed reduced by the intermediate reduction gear 71 falls below the rotational speed of the drive system 8. In normal mode, the drive torque is transmitted to the main reduction gear 6, where high torque for the main rotor 1 is generated.

[0053] On the other hand, Figure 2 shows that the power supply from battery modules 4 and 5, the operation of the auxiliary / emergency drive engine 2 (i.e., the electric motor), and the operation of the switchable coupling unit 3 are controlled or regulated by the auxiliary / emergency drive control unit 35.

[0054] The network assigned to the auxiliary / emergency drive control unit 35 is shown in detail in Figure 3. In this embodiment, the auxiliary / emergency drive control unit 35 is connected to a comprehensive sensor system that can evaluate the current state of the drive system. The dotted arrows represent inputs from sensors 11, 74, and 75 of the drive system that are operating in normal mode. Specifically, these are the rotational speed sensor 11 for the main rotor, the rotational speed sensor 74 for the power turbine, and the rotational speed sensor 75 for the gas generator. The design of these sensors is arbitrary. Since such sensors are usually installed in conventional helicopters, given this, there is little need to intervene in existing systems to implement the present invention. Based on the detected rotational speeds provided by sensors 11, 74, and 75, the auxiliary / emergency drive control unit 35 can evaluate the presence or absence of a limit condition by comparing it to a predetermined limit value (operational criterion).

[0055] Furthermore, the auxiliary / emergency drive control unit 35 can also calculate the torque acting on individual components based on the transmitted rotational speed and compare it with a preset limit torque.

[0056] Furthermore, the auxiliary / emergency drive control unit 35 is connected to a sensor / actuator 22 for the electric motor 21, which, for example, detects and transmits the motor's rotational speed and / or phase to the auxiliary / emergency drive control unit 35, and controls the motor output. It is also connected to a sensor / actuator 31 for the coupling unit 3, which supplies data (bold arrows in Figure 3) regarding the switching state and position of the coupling unit 3 and switches the coupling unit 3. Based on the transmitted data, the auxiliary / emergency drive control unit 35 can determine the torque currently being transmitted from the electric motor 21 to the main reduction gear 6. Control by the actuators allows for precise control of motor starting and coupling operation. This enables appropriate control of transitions from main mode (only the main drive engine supplies power) to emergency mode, auxiliary mode, or generator mode.

[0057] The implementation of emergency mode 200 is schematically shown in Figure 4. In step 202, as described above, the auxiliary / emergency drive control unit 35 determines whether a power drop has occurred ("Y") and whether the emergency mode should be initiated as a result (evaluation of data from sensors 11, 74, or 75). In step 204, the auxiliary / emergency drive control unit 35 first starts the electric motor 21, and then in step 206, it activates the coupling unit 3 to couple the electric motor 21 with the main reduction gear 6 (activation of actuators 22 and 31). In step 208, the status regarding the acting torque is checked (evaluation of data from sensors 11, 22, 31, 74, and / or 75). In step 210, the calculated torque is compared with the limit torque, and in step 212, feedback is provided to adjust the operation of the electric motor 21 and coupling unit 3 within the control loop.

[0058] Once a safe landing is complete, the connection between the electric motor 21 and the main reduction gear 6 can be disconnected again (clutch released) to allow the main rotor 1 to rotate.

[0059] The auxiliary mode 300 described above is shown in Figure 5. The basic procedure is very similar to that of the emergency mode; that is, the coupling operation is controlled in a control loop to monitor the torque. In step 302, the auxiliary mode 300 is activated via the input device of the pilot control 101 shown in Figure 3. More specifically, it is repeatedly checked whether the corresponding signal is present ("Y"). Before the auxiliary mode is actually executed, in step 303 it is checked whether the second battery module 5 has enough stored energy remaining to execute the auxiliary mode (see the battery sensor 51 connected to the auxiliary / emergency drive control unit 35 in Figure 3). If so ("Y"), in steps 304-312, the electric motor 21 and coupling unit 3 are controlled, as in Figure 4, to prevent damage due to excessive torque.

[0060] The generator mode 400 described above is shown in Figure 6. The event that initiates generator mode 400 is when the charge level of the second battery module 5 falls below a predetermined value, at which point the auxiliary / emergency drive control unit 35 periodically reads the current measurement from the battery sensor 51 (see Figure 3) and compares it to a predetermined limit value (step 401). In step 402, the presence or absence of a decrease in output or failure of the main drive engine is checked. In this case, it must be ensured that the electric motor 21 of the auxiliary / emergency drive engine becomes readily available to transmit drive torque. If such a situation does not occur, in step 406, the coupling unit 3 is activated first, and then the electric motor 21 or the auxiliary / emergency drive engine 2 switches to generator mode, and the second battery module 5 is charged. Checks for excessive torque in the coupling process are performed in a control loop similar to that in Figure 4 or 5.

[0061] It should be noted that the auxiliary / emergency drive control unit 35 can also check the battery charge status of the first battery module 4 using the corresponding battery sensor 41, as shown in Figure 3.

[0062] Figure 7 shows a side view of the main reducer 6 with an auxiliary / emergency drive engine 2 connected to the rotor mast 66. Figure 8 shows a corresponding cross-sectional view. The electric motor 21 has a motor shaft 32 that can be used with the auxiliary drive system 33 of the main reducer 6 via a switchable coupling unit 3. From the cross-sectional view in Figure 8, it can be seen that the auxiliary drive system 33 and the main drive system 8 are connected to the same input section of the main reducer 6, which is formed by a sun gear 63. For this purpose, the auxiliary drive system 33 is provided with a gear 34 and the main drive system 8 is provided with a gear 81. The sun gear 63 is also linked to the first stage 64 of a planetary gear provided on the main reducer 6. The second stage 65 of the planetary gear ultimately further reduces the reduction ratio and increases the torque. This torque is transmitted to the rotor mast 66 via elements that are well known to those skilled in the art, although they are not shown in detail here. Exemplary structures of implementable main reducers 6, which are not limited to the present invention, are disclosed, for example, in European Patent Application Publication No. 3323718. Main reducers of other concepts are similarly possible.

[0063] The above embodiments relate to helicopters. However, the principles of the present invention can be similarly and appropriately applied to other rotary-wing aircraft such as autogyros and quadcopters. [Explanation of symbols]

[0064] 1 Main rotor 11. Rotation speed sensor for the main rotor 2. Auxiliary / Emergency Drive Engine 21 Electric motor 22 Sensors / actuators for electric motors (speed and / or phase) 3. Switchable connecting unit 31. Sensor / actuator for connecting unit (switching state and position) 32. Motor shaft (electric motor) 33 Auxiliary drive system 34 Gears, bevel gears 35. Auxiliary / Emergency Drive Control Unit 4. The first battery module cannot be charged during flight. 41. Sensors for the first battery module (charge status, temperature, voltage, etc.) 5. Second battery module, rechargeable during flight. 51. Sensors for the second battery module (charge status, temperature, voltage, etc.) 6 Main reducer 63 Input, Sun Gear 64 Planetary gear, first stage 65 Planetary gear, second stage 66 Rotor Mast 7 Main drive engine 71 Intermediate reduction gear 72 Freewheel Clutch 74. Rotational speed sensor for power turbines 75. Rotation speed sensor for gas generators 8 Main drive system 81 Gears, bevel gears 9. Tail rotor reducer 99 Tail Rotor 10 Rotary-wing aircraft, helicopters 101 Pilot-controlled, with input device 200 Emergency Mode (Start) 300 Auxiliary Mode (Start) 400 Generator Mode (Start)

Claims

1. A drive system for a rotary-wing aircraft (10), A main drive engine (7) is configured to generate power capable of driving the main rotor (1) of the rotary-wing aircraft (10), which is equipped with multiple rotor blades. A main reduction gear (6) is configured to convert the power generated by the main drive engine (7) into torque acting on the main rotor (1), Similarly, an auxiliary / emergency drive engine (2) is configured to generate power for driving the main rotor (1), Includes, The auxiliary / emergency drive engine (2) is a drive system that can be connected to the main reduction gear (6) via a switchable coupling unit (3).

2. The auxiliary / emergency drive engine (2) is equipped with an electric motor (21), The drive system according to claim 1, wherein the main drive engine (7) preferably comprises a thermodynamic engine.

3. The drive system according to claim 2, further comprising a first battery module (4) configured to supply power to the electric motor (21) of the auxiliary / emergency drive engine (2).

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

5. The switchable coupling unit (3) is arranged to connect and disconnect the drive shaft (32) of the electric motor (21) to the auxiliary drive system (33), The auxiliary drive system (33) is connected to the input section of the main reduction gear (6), The power generated by the main drive engine (7) is supplied to the main reduction gear (6) via the main drive system (8). The drive system according to claim 3 or claim 4, wherein the main drive system (8) is connected to the same input section (63) of the main reduction gear (6) as the auxiliary drive system (33).

6. The drive system according to claim 5, wherein the input section (63) of the main reduction gear (6) is composed of a sun gear that is interlocked with a planetary gear system (64, 65).

7. The drive system according to any one of claims 3 to 6, further comprising an auxiliary / emergency drive control unit (35) configured to operate the electric motor (21) according to an operating criterion and to operate the switchable coupling unit (3) to connect or disconnect the electric motor (21) from the main reduction gear (6).

8. The auxiliary / emergency drive control unit (35) is connected to drive sensors (22, 31, 11, 74, 75), detects a malfunction or impending malfunction of the main drive engine (7), operates the electric motor (21) according to the detection result as an operating criterion, switches the coupling unit (3) to connect the electric motor (21) to the main reduction gear (6), and causes the main rotor (1) to be driven by power from the electric motor (21) in emergency mode (200), as described in claim 7, drive system (10).

9. The drive system according to claim 8, wherein the drive sensors (22, 31, 11, 74, 75) include one or more sensors for detecting at least one of the following: (a) Rotor speed (b) Rotation speed of the gas generator (c) Rotational speed of the power turbine

10. The system further includes a second battery module (5) configured to supply power to the electric motor (21) of the auxiliary / emergency drive engine (2), The auxiliary / emergency drive control unit (35) is connected to battery sensors (41, 51) to detect when the battery charge state of the first battery module and / or the second battery modules (4, 5) is low, and according to the detection result as an operating criterion, the coupling unit (3) is switched to connect the electric motor (21) to the main reduction gear (6), to operate as a generator in generator mode (400), and to charge the second battery module (5) by converting a portion of the output of the main drive engine (7) into electrical output, as described in any one of claims 7 to 9.

11. The first battery module (4) is configured to be unable to be charged during flight; The drive system according to claim 10, wherein the second battery module (5) is configured to be rechargeable during flight operation.

12. The auxiliary / emergency drive control unit (35) is connected to the pilot control unit (101), which is equipped with an input device and generates an input signal according to the content input by the pilot to the input device and transmits it to the auxiliary / emergency drive control unit. The drive system according to any one of claims 7 to 11, wherein the auxiliary / emergency drive control unit operates the electric motor using the transmitted input signal as an operating reference, switches the coupling unit (3) to connect the electric motor (21) to the main reduction gear (6), so that the main rotor (1) is driven in auxiliary mode (300) by the power of the electric motor (21) in addition to the power of the main drive engine (7).

13. The drive system (10) according to claim 12, relating to claim 10 or claim 11, wherein the auxiliary / emergency drive control unit (2) is configured to perform the auxiliary mode (300) by the electric motor (21) based solely on power supplied from the second battery module (5).

14. The drive system according to any one of the above claims, wherein the first battery module (4) is not connected to any electrical consuming equipment except for the electric motor (21), the auxiliary / emergency drive control unit (35), and the corresponding battery sensor.

15. The main drive engine (7), the main reduction gear (6), and the auxiliary / emergency drive engine (2) are basically arranged along the longitudinal axis of the rotorcraft (10), and the auxiliary / emergency drive engine (2) and the main drive engine (7) are arranged facing each other with respect to the main reduction gear (6). The drive system according to any one of the above claims, wherein the auxiliary / emergency drive engine (2) is preferably positioned in front of the main reduction gear (6) in a predetermined flight direction of the rotor-wing aircraft (10).

16. A rotary-wing aircraft (10), particularly a helicopter, having a drive system as described in any one of the above claims, The auxiliary / emergency drive engine (2) is located in an installation space above the cargo storage space within the cabin, particularly above the passenger cabin, in a rotary-wing aircraft.

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

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