Hybrid propulsion systems for helicopters

Abstract

The invention relates to a hybrid transmission system (4) for a helicopter comprising a controller (5, 7, 11) and a transmission shaft (3), the helicopter having a main rotor (1) connected to a gearbox and capable of stabilizing a flight attitude predefined by the pilot. The hybrid transmission system comprises a pilot controller (5) and both a combustion engine (VM) (6) and an electric motor (EM) (10), both of which are directly coupled to the transmission shaft (3). The combustion engine (6) is connected to a combustion engine controller (7), and the electric motor (10) is connected to an electric motor controller (11). According to the invention, a torque sensor (17) and a tachometer (18) are each positioned on the transmission shaft (3), wherein both the combustion engine controller (7) and the electric motor controller (11) can each receive values ​​for a current rotational speed (DZ) and a current torque (DM) during operation. Predefined values ​​of the speed (DZ0) and torque (DM0) at which the burner (6) can improve its optimal efficiency by using said values ​​are stored and can be retrieved by the electric motor controller (11), and said speed (DZ0) can also be retrieved by the burner controller (7). First instructions are stored in the electric motor controller (11) to always apply a driving or braking force from the electric motor (10) to the transmission shaft (3), said force causing the burner (6) to automatically generate said torque (DM0) at the transmission shaft (3) when it has reached or maintains the optimal speed (DZ0) at the transmission shaft (3), at which torque the burner achieves said optimal motor power. The invention also relates to a corresponding method.

Description

Technical Field

[0001] The invention relates to a hybrid propulsion system with a controller and a transmission shaft for a helicopter having a main rotor connected to a gearbox for stabilizing a flight attitude set by the pilot, the hybrid propulsion system comprising a pilot controller, a combustion machine (VM) and an electric motor (EM), the combustion machine and the electric motor acting directly on the transmission shaft (3). The VM is connected to a VM controller capable of regulating the delivery of fuel from a fuel tank to the VM in order to provide the required propulsion power at the transmission shaft, and the EM is connected to an EM controller capable of driving the EM by discharging a battery or charging the battery by applying mechanical power to the EM, thereby accelerating or decelerating the transmission shaft, respectively. The invention further relates to a method for operating such a hybrid propulsion system. Background Art

[0002] As in the automotive industry, the use of additional electric motors for propulsion, in particular hybrid propulsion, is also known for helicopters.

[0003] A system similar to the above is known from US 2017 / 0225573 A1. It includes an internal combustion engine and an electric motor arranged between the internal combustion engine and the gearbox of the main rotor. The same is true of US 2018 / 0354635 A1. This document also describes a method for regulating the distribution between the combustion engine and the electric motor using various computer systems.

[0004] Another hybrid system is known from EP 3162713, which operates a helicopter using both an electric motor and a combustion engine. The purpose of the control system described in this document is to absorb power peaks from the electric motor, allowing the combustion engine to operate as much as possible in a "steady-state" mode (also known as "moving average power"). To achieve this, the control signal used is divided into a high-frequency component signal and a low-frequency component signal, with the faster high-frequency signal being transmitted to the electric motor and the slower low-frequency signal being sent to the combustion engine. Thus, sharp changes are managed by the electric motor, while the combustion engine only has to handle power fluctuations at a slower, "damped" rate, as it were. The sacrifice of this distribution is safety in the event of a failure of one of the engines. Since neither engine receives a complete signal, the remaining operating engine cannot handle the flight requirements on its own. Additional monitoring systems must detect the failure of an engine and immediately initiate measures to ensure that the remaining engine receives a complete signal. Any required additional control or monitoring systems themselves represent a risk to flight safety. Summary of the Invention

[0005] The object of the present invention is to describe a hybrid propulsion system by which the safest possible operation of a helicopter can be ensured. Another object of the invention is to propose a method according to which safe operation can be performed. This safe operation must also be performed with minimal fuel consumption.

[0006] These objects are solved by the features of the first claim of the corresponding category. Further advantageous variants are described in the dependent claims.

[0007] According to the invention, in a hybrid propulsion system as described in the introduction, at least one torque sensor and one tachometer are each arranged on the transmission shaft, wherein both the VM controller and the EM controller can each receive values ​​of the current speed DZ and the current torque DM during operation.

[0008] Also stored are specified values ​​of speed DZ0 and torque DM0 at which the VM achieves optimal efficiency. These values ​​can be retrieved by the EM controller, wherein the first of these values, DZ0, can also be retrieved by the VM controller.

[0009] The VM controller is able to reach a preset speed DZ0 at the propeller shaft by adjusting the power from the VM and to autonomously keep this speed constant at any time, which in turn also stabilizes any flight attitude set by the pilot controller. The EM controller is also able to further accelerate or decelerate the propeller shaft by engaging the EM, which causes the speed DZ to change, and the VM controller automatically adjusts the output at the VM to again reach the preset speed DZ0 at the propeller shaft and maintain it.

[0010] A first instruction is stored in the EM controller, according to which the EM must constantly apply this type of acceleration or deceleration force to the propeller shaft so that the VM automatically generates a torque DM0 on the propeller shaft when it has reached or maintained an optimal speed DZ0 at the propeller shaft, at which torque it achieves optimal engine output.

[0011] The EM is preferably placed between the VM and the main rotor's gearbox 1. The speed DZ can be measured at any point on the propeller shaft and is the same at all points. At least one torque sensor should be placed between the VM and the EM to determine the VM's load on the propeller shaft. An additional torque sensor can be placed between the EM and the gearbox to determine the total load on the propeller shaft. However, the most important element for adjusting the EM controller is the torque sensor between the VM and the EM, as it indicates the output at the VM that should be operated at maximum efficiency according to the first command.

[0012] A direct data signal line for use during takeoff and landing of the helicopter can be provided between the pilot controller and the VM controller. During these phases, the first command need not be applied. An indirect connection exists permanently via the helicopter's flight attitude: if the pilot trims the rotor blades to a steeper pitch to gain altitude, the higher load immediately causes the speed DZ at the drive shaft to drop, based on which the power demand in normal operation is adjusted according to the first command.

[0013] Additionally, a fuel level gauge may be located on the fuel tank and a state-of-charge indicator may be located on the battery. Each of the fuel level gauge and state-of-charge indicator can transmit its measured data while the EM controller is operating. The amount of energy still available under each condition can be calculated by the calculation unit. If necessary, the EM controller can operate according to a second instruction different from the first instruction. This can be done to protect the battery from overcharging or undercharging, conserve fuel, and / or temporarily operate the VM at a lower power level to reduce emissions.

[0014] The key objective is that the VM controller and the VM are able to autonomously achieve the desired speed DZ at the propeller shaft at any time in order to achieve or maintain the stable flight attitude set by the pilot controller. This means that a helicopter with VM can be equipped with an EM and EM controller without intervening in the existing VM control system. As a result, in the event of a system error, if the EM and / or EM controller fails, the helicopter can be flown normally using only the VM.

[0015] The method according to the invention for operating a hybrid propulsion system with controls according to the invention for a propeller shaft of a helicopter ensures the flight attitude set by the pilot using the hybrid propulsion system. The method performs the following steps:

[0016] The current values ​​of the speed DZ and torque DM at the drive shaft are continuously measured and transmitted to both the EM controller and the VM controller. Preset values ​​for speed DZ0 and torque DM0 are stored in a memory, where both values ​​DZ0, DM0 can be retrieved by the EM controller and at least speed DZ0 can be retrieved by the VM controller. Both controllers continuously calculate the deviations of the measured values ​​DZ, DM from their known preset values ​​DZ0, DM0.

[0017] Once the pilot, via the pilot controls, requests a change in the output of the transmission shaft to achieve a desired flight attitude, causing a change in the speed (DZ) of the transmission shaft, the VM controller changes the output of the VM in a manner that re-acquires the preset speed DZ0, not too rapidly, based on the deviation between the current speed DZ and the preset speed DZ0.

[0018] This is explained in more detail in the following example: The VM controller is adjusted so that the VM continuously applies a load to reach and maintain the optimal speed DZ0. If the pilot trims the rotor blades to gain altitude, speed DZ decreases as a result. The VM responds to this decrease in speed DZ with increased output, and the torque DM generated by the VM increases. This, in turn, has the effect of increasing speed DZ. Once the speed reaches the preset value DZ0 again and remains constant, the VM controller no longer has reason to change the engine output. The VM continues to operate unchanged, but now with a greater torque DM than before trimming the rotor blades. As the helicopter descends, a corresponding reaction occurs, and the torque DM applied by the VM decreases.

[0019] However, in the method for utilizing a hybrid propulsion system according to the present invention, the EM controller engages according to its first command. Based on the deviation of the current value of speed DZ and / or torque DM from the corresponding specified values ​​DZ0, DM0, the EM changes its output more quickly than the VM, achieving the following effect: the VM applies the preset torque DM0 after adjusting its output to the preset speed DZ0, at which the VM achieves optimal efficiency. The EM controller achieves this by using the mechanical power of the EM to charge the battery or using the charge in the battery to operate the EM.

[0020] In the example above, the EM controller is therefore subsequently engaged. The preset values ​​of speed DZ0 and torque DM0 are known to the EM controller, which is able to calculate the respective differences from the current values ​​DZ, DM based on the measurements it receives.

[0021] The EM controller initially operates according to its first instruction. Therefore, if the pilot trims the rotor blades to gain altitude, the speed initially decreases, as previously described. However, before the VM can increase its output by generating more torque, the EM responds more quickly by generating an additional load request, allowing the desired speed DZ0 to be immediately regained. The VM controller, which also continuously monitors the speed, detects only brief, minor deviations from the preset speed DZ0, which are immediately compensated by the EM because it immediately supplies the necessary load to compensate for the deviation. Due to the VM controller's slow response time, the VM does not increase its output, but instead maintains the torque DM it initially generated.

[0022] The same thing happens during descent when the pilot flattens the pitch of the rotor blades. The EM's batteries are charged because the EM slows the propeller shaft before the VM can compensate for the increase in speed and reduce the power it applies.

[0023] On the one hand, this first instruction of the EM controller thus adjusts the speed DZ0 at the drive shaft and keeps this speed constant by actuating the EM accordingly. This in turn prevents a change in the load on the VM, so the torque of the VM remains constant. This is desirable when the torque is equal to the preset torque DM0. Although this is the case, the efficiency remains optimal.

[0024] On the other hand, the EM controller also continuously checks whether the torque DM currently generated by the VM at the drive shaft corresponds to the preset torque DM0. Deviations may occur, for example, after takeoff, during climb or descent, or after the EM has been deactivated, for example because the state of charge of the battery is too low. When a deviation in the torque is detected, the first instruction of the EM controller will therefore also adjust this measured torque DM to the preset value DM0 as follows: If the measured torque is too high, the EM controller adjusts DZ to a constantly slightly higher value. The VM controller responds to this by reducing the output, which causes the torque generated by the VM to steadily decrease. The EM controller maintains the slightly increased speed until the measured torque DM matches the preset torque DM0. Once the preset torque has been reached, the output at the EM is rapidly reduced again until the preset speed DZ0 is regained. Thus, the preset torque DM0 is also maintained. The VM now operates with optimal efficiency, and the EM controller keeps DZ constant again so that the VM delivers its constant optimal output.

[0025] Therefore, the EM controller increases the output at the EM in operation in response to too low speed (in the case of DZ < DZ0) and / or in response to too much torque (in the case of DM > DM0), and vice versa.

[0026] According to the invention, if the EM controller is deactivated, the VM controller automatically ensures a smooth flight attitude by adjusting the speed to the preset value DZ0, since the necessary propulsion power is provided by the VM. This requires no adjustment and no further monitoring.

[0027] In a preferred method, using measurement data from a fuel level gauge of the fuel tank and / or a state of charge indicator of the battery, the EM controller can calculate the still available energy and, based on this, temporarily deviate from the first instruction and operate according to a second instruction. In this second instruction, the battery can be selectively charged or discharged in order to protect the battery, save fuel or temporarily operate the VM at a lower power to reduce emissions.

[0028] For example, this is used to prevent deep discharge or overcharging of the battery. On the other hand, the EM can be selectively used more often at higher altitudes, since the fuel consumption increases relatively sharply at higher altitudes. Additionally, during the takeoff and / or landing phases, only the EM can be operated in order to reduce noise and exhaust emissions on land, or only the VM can be used as required.

[0029] Whereas in EP 3162713, the pilot signal is split into a high-frequency control signal and a low-frequency control signal to achieve the desired distribution of output between the two engines, with the present invention, the output division during normal operation is adjusted based on a first command from the engine (EM) by adjusting the measured speed DZ and measured torque DM to stored set points DZ0 and DM0. During normal flight, except for takeoff and landing, the controllers of both engines receive no control signals from the pilot. The EM and VM adjust their outputs so that the preset speed DZ0 remains constant, with the EM responding more quickly to compensate for any deviations before the slower VM can respond. The EM also adjusts the torque DM delivered by the VM to the preset value DM0 based on the additional positive or negative power output of the first command. Thus, the hybrid propulsion system described herein is easy to control and ensures process reliability even in the event of an unexpected VM failure.

[0030] In this way, the hybrid propulsion system always flies with a load distribution that uses the available fuel most efficiently. However, this is not achieved by performing complex calculations, but directly and simply based on the determination of the current values ​​of speed DZ and torque DM in each case and knowledge of the preset values ​​DZ0, DM0.

[0031] If the EM fails, the hybrid propulsion system according to the invention becomes a conventional VM propulsion system, since the VM controller supplies through the VM with a defined time delay exactly the respective torque required at the propeller shaft necessary to reach and maintain the flight attitude set by the pilot in each case.

[0032] If the VM fails, the speed decreases, and the EM immediately compensates with additional output. This maintains constant speed DZ, ensuring flight safety. The EM controller also determines that the torque DM delivered by the VM is absent, meaning the VM simply ceases operation. Therefore, the EM takes over the task of generating total power until the VM resumes operation or the helicopter lands. Safe flight is always guaranteed.

[0033] Because both controllers receive the same information derived directly from the flight attitude, each engine can autonomously ensure the desired flight attitude. Load sharing between the two engines occurs completely automatically, as the EM very quickly detects and executes its share of the work, allowing the VM to continuously operate within the optimal range.

[0034] Additionally, when fuel is low, the EM controller can increase the load on the EM to conserve fuel. A deviation from the primary command can also occur to prevent deep discharge or overcharging of the battery. The EM can also engage the booster's power to deliver additional output, for example, when flying over high mountains. On the other hand, if battery charge permits, increased use of the EM can be achieved in high-temperature and / or extreme-altitude conditions, where VM power is significantly reduced due to thin air, to increase the limit on available power or conserve fuel. The EM can also be operated independently during takeoff and / or landing to reduce noise and exhaust emissions in the takeoff and / or landing area.

[0035] Once the abnormal situation no longer exists, the first instruction is reactivated. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. In the drawings:

[0037] 1 Figure 1 is a schematic representation of a hybrid propulsion system according to the present invention;

[0038] 2 Figure 2 A diagram depicting load distribution in various flight attitudes, such as climb, level flight, and descent. DETAILED DESCRIPTION

[0039] Figure 1 The hybrid propulsion system 4 according to the invention is shown in more detail than is necessary for a simple description of the invention. Figure 1 A partial area of ​​a helicopter, which is not important for the purposes of the present invention, is shown, with a transmission shaft 3, a gearbox 1 for the main rotor, and a tail rotor 2. A combustion engine (VM) 6 and an electric motor (EM) 10 are arranged in parallel on the transmission shaft 3, with the EM 10 preferably being arranged between the VM 6 and the gearbox 1 for the main rotor. Other configurations are also possible.

[0040] The pilot control unit 5 is responsible for receiving the pilot's control commands for trimming the main rotor blades, so that the engine output to be set is indirectly calculated as the required speed DZ0 at the transmission shaft 3. A data signal line 19 from the pilot control unit to the VM control unit 7, which is optional for the flight mode according to the invention, can be used for take-off and landing maneuvers.

[0041] VM 6 is connected to a fuel tank 8, which is connected to a VM controller 7, which regulates the fuel supply from tank 8 to VM 6 to provide the desired propulsion output at propeller shaft 3. EM 10 is also preferably connected to battery 14 via a power converter 12 and a charging unit 13, which may be equipped with current peak buffering. EM 10 can be operated by the charge in battery 14, or battery 14 can be charged by mechanical power from EM 10, resulting in acceleration or deceleration of propeller shaft 3 in either case. EM controller 11 is at least indirectly connected to EM 10, for example, via power converter 12, and regulates the EM to deliver the desired acceleration or deceleration force at propeller shaft 3.

[0042] Furthermore, a fuel level gauge 9 may be arranged on the fuel tank 8 and a charge state indicator 15 may be arranged on the battery 14 , both of which may transmit their measurement data to the calculation unit 16 during operation.

[0043] At least one torque sensor 17 and one tachometer 18 are each arranged on the transmission shaft 3. During operation, the VM controller 7 and the EM controller 11 receive data from the at least one torque sensor 17 and one tachometer 18, respectively.

[0044] A calculation unit 16 is connected to the EM controller 11 and the VM controller 7. The calculation unit is used to calculate the energy still available, the required torque at the drive shaft 3, and / or to manage the EM controller 11. The calculation unit comprises a data memory 20 in which values ​​of a preset speed DZ0 and a preset torque DM0 are stored, wherein based on these values ​​an optimal power coupling of the VM 6 is achieved and at which the efficiency of the VM is maximized.

[0045] In operation, the EM controller 11 initiates load distribution to the VMs 6 and EMs 10. Figure 2 Schematically represented in .

[0046] The dashed line plot in the top diagram shows the flight attitude, specifically the altitude H, as requested by the pilot-controller 5 over time. In this context, altitude "0" is understood to mean the ground. The solid line represents the effective altitude H, slightly delayed. In the first phase (I), the helicopter climbs steadily until it reaches the desired altitude H1. In the second phase (II), it continues to fly horizontally at this altitude, and in the third phase (III), it descends again. Between each flight phase, there is a period of time before the newly designated target is reached.

[0047] The plot in the middle diagram schematically indicates the total load P H (i.e., total torque at the main rotor (dashed line)), load P at VM 6VM (dotted line) and the load P at EM 10 EM (dotted line). The bottom graph indicates the velocity DZ.

[0048] After the takeoff procedure, VM 6 operates at a constant high level. In the first phase I, once VM 6 reaches the preset optimal load P VM , the EM 10 acts as an additional transmission by delivering torque DM0. The EM supports the VM (6) during phase I of the climb until the preset altitude H1 is reached, i.e. the pilot slightly flattens the angle of attack of the rotor blades. The takeoff procedure can be carried out according to instructions other than the first instruction until the helicopter is safely airborne.

[0049] Leveling the rotor blades at the beginning of Phase II causes a brief, slight increase in speed DZ, as shown in the bottom graph. EM 10 immediately responds by reducing its output until speed DZ again matches setpoint DZ0. Altitude now remains constant throughout Phase II. VM 6 is sluggish and therefore does not respond to this brief change. In the example shown, the load on EM 10 during Phase II is negative, so the EM acts as a generator, returning the excess energy available from VM 6's output to battery 14. VM 6 also does not change its load during Phase II.

[0050] When preparing for a descent, at the beginning of Phase III, the pilot again slightly flattens the rotor blades, causing another brief increase in speed DZ. EM 10 responds by reducing its output again. However, this time, the EM adjusts to a speed DZ slightly above the preset value DZ0 according to the second command. Energy recovery at EM 6 is now faster because EM 10 continues to decelerate drive shaft 3. Due to the slightly increased speed DZ, VM 6 now responds by steadily reducing its output. Simultaneously, EM 10 maintains the increased DZ, as represented by the bottom plot in Phase III: the solid line representing the current speed DZ is above the dashed line representing DZ0.

[0051] When the current speed DZ is greater than the setpoint speed DZ0, the output at VM 6 is reduced, and the noise and exhaust emissions at the landing site are also reduced. This is achieved by the EM 10 steadily reducing its generated power, so that the EM also reduces its deceleration effect.

[0052] According to the present invention, the speed DZ of the propeller shaft 3 is adjusted solely by the engine 10 according to a first command, so that the speed is maintained constant by VM6 at DM0 at a preset speed DZ0. According to a second command, as shown in phase III, the behavior deviates from the first command in order to selectively reduce the load on VM6. In addition to the aforementioned emission reduction, other reasons can also lead to deviations from the first command. In particular, these reasons include the deliberate charging and discharging of the battery 14, if the battery's state of charge so requires. The engine 10 can also be used as a booster, for example, to deliver a brief increase in power or to save fuel at higher altitudes.

[0053] For example, if the EM controller 11 has information about the charge state of the battery 14 and the fuel remaining in the tank, the second instruction can be adjusted based on the information about energy reserves by performing noise regulation according to the flyover altitude and / or by prioritizing the definition of the planned flight path.

[0054] Reference Symbol List

[0055] 1 Gearbox with main rotor

[0056] 2 tail rotors

[0057] 3 Drive shaft

[0058] 4 Hybrid Propulsion System

[0059] 5 Pilot Controls

[0060] 6 Burner (VM)

[0061] 7 VM Controller

[0062] 8 fuel tanks;

[0063] 9 Fuel level gauge

[0064] 10 Electric Motor (EM)

[0065] 11 EM controller

[0066] 12 Power Converters

[0067] 13 Charging unit

[0068] 14 Batteries

[0069] 15 Charging status indicator

[0070] 16 computing units

[0071] 17 Torque sensor

[0072] 18 Tachometer

[0073] 19 data signal line

[0074] 20 Data memory with the value of best VM speed

[0075] I. First stage, climbing

[0076] II Phase II, level flight

[0077] III Stage III, descent

[0078] T time

[0079] H Current altitude

[0080] H1 Target Height

[0081] P Power (torque redundancy)

[0082] P H Total power

[0083] P EM Output at EM

[0084] P VM Output at VM

[0085] DZ Speed ​​measured at the drive shaft

[0086] DZ0 Optimal Speed

[0087] DM measures the torque at the drive shaft

[0088] DM0 target torque

Claims

1. A hybrid propulsion system (4) for a helicopter having a controller (5, 7, 11) and a transmission shaft (3), the helicopter having a main rotor (1) connected to a gearbox and capable of stabilizing a flight attitude set by a pilot, the hybrid propulsion system (4) comprising: -pilot controls (5); a combustion machine VM (6) and an electric motor EM (10), both of which act directly on the transmission shaft (3), - wherein the VM (6) is connected to a VM controller (7) capable of regulating the fuel supply from a fuel tank (8) to the VM (6) so as to provide the required propulsion power at the propeller shaft (3); - and wherein the EM (10) is connected to an EM controller (11) capable of operating the EM (10) by discharging a battery (14) or charging the battery (14) by applying mechanical power to the EM (10), thereby accelerating or decelerating the drive shaft (3), respectively, It is characterized by: - one or more torque sensors (17) and tachometers (18) are each arranged on the transmission shaft (3), and both the VM controller (7) and the EM controller (11) are capable of maintaining values ​​of both the current speed (DZ) and the current torque (DM) during operation, - wherein the specified values ​​of the preset speed (DZ0) and the preset torque (DM0) at which the VM (6) can achieve its optimum efficiency are stored in a memory and can be retrieved by the EM controller (11), wherein the preset speed (DZ0) can also be retrieved by the VM controller (7), - and the VM controller (7) is capable of autonomously reaching the preset speed (DZ0) at the transmission shaft (3) at any time and maintaining the preset speed (DZ0) by adapting the output of the VM (6) so as to keep stable any flight attitude set by the pilot controller (5), - wherein the EM controller (11) is additionally capable of accelerating or braking the drive shaft (3) by engaging the EM (10), whereby the VM controller (7) is capable of automatically adapting the output at the VM (6) based on the current speed (DZ) in order to achieve or maintain the preset speed (DZ0) at the drive shaft (3), - and wherein a first instruction is stored in the EM controller (11) for continuously applying such acceleration or braking force from the EM (10) to the transmission shaft (3), thereby causing the VM (6) to automatically generate the preset torque (DM0) at the transmission shaft (3) when it has reached or maintained the preset speed (DZ0) at the transmission shaft (3), at which the VM (6) obtains optimal engine output.

2. The hybrid propulsion system (4) according to claim 1, characterized in that The EM (10) is arranged between the VM (6) and the gearbox of the main rotor (1).

3. The hybrid propulsion system (4) according to claim 1 or 2, characterized in that A direct data signal line (19) is provided between the pilot controller (5) and the VM controller (7) for take-off and landing of the helicopter.

4. A hybrid propulsion system (4) according to claim 1 or 2, characterized in that A fuel level gauge (9) is also arranged on the fuel tank (8) and a charge state indicator (15) is arranged on the battery (14), and both the fuel level gauge (9) and the charge state indicator (15) are capable of transmitting measurement data of the fuel level gauge (9) and the charge state indicator (15) when the EM controller (11) is in operation.

5. The hybrid propulsion system (4) according to claim 4, characterized in that A calculation unit (16) is provided for calculating the energy still available and, if necessary, for calculating a second instruction different from the first instruction in order to protect the battery from overcharging and undercharging, save fuel and / or temporarily operate the VM (6) at a lower power to reduce emissions.

6. A method for using a hybrid propulsion system (4) of a helicopter according to any one of the preceding claims, comprising a controller (5, 7, 11) and a transmission shaft (3) for operating the hybrid propulsion system (4) with respect to the transmission shaft (3) of the helicopter to ensure a flight attitude set by the pilot, characterized by the following steps: - continuously measuring the current speed (DZ) and the current torque (DM) at the transmission shaft (3) and transmitting said current speed (DZ) and said current torque (DM) to both the EM controller (11) and the VM controller (7), - storing a preset speed (DZ0) and a preset torque (DM0) in a memory, wherein the preset speed (DZ0) and the preset torque (DM0) can be retrieved by the EM controller (11) and at least the preset speed (DZ0) can be retrieved by the VM controller (7), wherein the controllers (7, 11) continuously calculate the deviations of the measured current speed (DZ) and the measured current torque (DM) from the preset speed (DZ0) and the preset torque (DM0), - once the pilot generates, through the pilot control (5), a variable request for power at the transmission shaft (3) in order to achieve a desired flight attitude, also causing a change in the current speed (DZ) at the transmission shaft (3), - the VM controller (7) slowly changes the output at the VM (6) based on the deviation between the current speed (DZ) and the preset speed (DZ0) in such a way that the preset speed (DZ0) is obtained, - the EM controller (11) changes the output at the EM (10) faster than the VM (6) according to a first instruction of the EM controller (11) based on the difference between the current speed (DZ) and / or the current torque (DM) and the preset speed (DZ0) and / or the preset torque (DM0), in such a way that the VM (6) applies the preset torque (DM0) when the VM (6) has adjusted the output of the VM (6) to the preset speed (DZ0) with a time lag, at which the VM (6) obtains optimal efficiency, - The battery (14) is charged by the mechanical power at the EM (10) or the EM (10) is charged by the charging operation in the battery (14). - When the EM controller (11) is disabled, the VM controller (7) automatically provides the required propulsion power through the VM controller (7) based on adjusting the speed to the preset speed (DZ0), and thus ensures a stable flight attitude.

7. The method according to claim 6, wherein The EM controller (11) determines the amount of energy still available based on the measurement data from the fuel level gauge (9) of the fuel tank (8) and / or the charge status indicator (15) of the battery (14), and thus operates according to a second instruction different from the indication of the first instruction in order to selectively charge or discharge the battery (14), thereby protecting the battery, saving fuel or temporarily operating the VM (6) at a lower power to reduce emissions.

8. The method according to any one of claims 6 or 7, wherein Only the EM (10) is operated during the takeoff and landing phases in order to reduce noise and exhaust emissions in the landing area.

9. The method according to claim 6 or 7, wherein: During operation, the EM controller (11) increases the output at the EM (10) when the speed is too low (DZ < DZ0) and / or the torque is too high (DM > DM0), and vice versa.

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