Drive device for an aircraft, having a fuel cell device

Abstract

The invention relates to a drive device (1) for an aircraft (2), having: a fuel cell device (3) which can be connected to a hydrogen tank (4, 4a, 4b, 4c, 4d); an electric drive motor (5) which is electrically connected to the fuel cell device and is designed to drive a propeller (6) about a drive axis (7); a first fire protection chamber (8) in which the fuel cell device and in particular a hydrogen tank are arranged; a first fire protection wall (8a) which extends completely or partially around the first fire protection chamber; a second fire protection chamber (9) in which at least the electric drive motor is arranged; and a second fire protection wall (9a) which extends completely or partially around the second fire protection chamber, wherein the first and second fire protection walls are at least partially different from one another, and wherein the first fire protection chamber is separated from the second fire protection chamber by at least one fire protection wall.

Description

[0001] APUS ZERO EMISSION GMBH

[0002] 247 PCT 2709

[0003] Propulsion system for an aircraft with a fuel cell system

[0004] The invention lies in the field of aeronautical engineering, mechanics and electrical engineering and is particularly advantageous for hydrogen-powered aircraft, but can also be used for other propeller-driven means of transport, such as boats or hovercraft vehicles.

[0005] Various principles are known for propelling aircraft, with internal combustion engines in the form of piston engines and turbines being particularly common in the past. The use of electric motors to drive propellers is also generally known. Consideration has been given to powering these electric motors with electrochemical batteries; however, these batteries are relatively heavy in relation to the amount of energy they store.

[0006] For this reason, aircraft powered by electric propulsion motors are currently being developed, with the electrical energy generated / converted in a fuel cell. However, fuel cells, along with their necessary peripheral components, also have a size and weight that necessitates a highly efficient design to save space and weight. Furthermore, care must be taken to ensure that the substances used in the fuel cell are supplied in a suitable form and handled in a fire-safe manner, especially when these substances include hydrogen, which has a very small molecular size.

[0007] Patent application US2021151783A1 discloses a propulsion system for an aircraft comprising a combination of an electric motor with a fuel cell and an air compressor.

[0008] Patent application US2021261260A1 discloses the assembly of various components of an electric drive for an aircraft with a fuel cell in a common frame.

[0009] Against the background of the prior art, the present invention is based on the objective of creating a drive device that achieves the most effective fire protection possible with the lowest possible weight and space requirement.

[0010] The problem is solved using the features of the independent patent claims, where the dependent patent claims present particular implementations of a drive device.

[0011] The invention relates accordingly to a propulsion device for a means of transport, in particular an aircraft, comprising a fuel cell device that can be connected to a hydrogen tank and a drive electric motor electrically connected to the fuel cell device, which is configured to drive a propeller around a drive shaft, as well as a first fire protection compartment in which the fuel cell device and in particular a hydrogen tank is arranged, and a first fire protection wall that completely or partially surrounds the first fire protection compartment, as well as a second fire protection compartment in which at least the drive electric motor is arranged, and a second fire protection wall that completely or partially surrounds the second fire protection compartment.wherein the first and the second fire-resistant walls are at least partially different from each other and wherein the first fire-resistant room is separated from the second fire-resistant room by at least one fire-resistant wall.

[0012] In such a propulsion system, the fuel cell assembly can comprise one or more fuel cells, in which electrical energy is generated in the form of current and voltage. In a fuel cell stack, several fuel cells are typically connected electrically in series. In most cases, fuel cells are supplied with hydrogen and oxygen. Handling hydrogen and oxygen in concentrated form can create fire hazards or exacerbate existing fire hazards, for example, in the electrical system of an aircraft, boat, or other propeller-driven vehicle. Furthermore, when handling hydrogen, the small molecular size of the substance means it penetrates many materials more readily than other substances.

[0013] For this reason, according to the invention, at least two fire compartments are formed, which are separated from each other by at least one fire wall. Furthermore, a fire wall can be provided for each of the fire compartments, which at least partially surrounds or encloses it. In many cases, the respective fire wall can enclose the first and / or second fire compartment almost completely, for example, with the exception of ventilation openings. Fire walls can be made of various materials, for example, at least partially of a metal, in particular at least partially of stainless steel. However, the fire walls can also be made of other, flame-resistant materials or incorporate such materials, such as plastics or ceramics.Fire-resistant walls can also have a fire-resistant coating or paint on their side facing the respective fire compartment. This coating or paint can be fire-retardant or can release fire-retardant or fire-extinguishing substances in the event of a fire. The first and second fire-resistant walls are intended to prevent or at least delay the spread of a fire from the equipment located within the fire compartment in one or more directions, for example, to equipment located outside the fire compartment, even if the fire-resistant wall does not completely surround the compartment.

[0014] Each fire compartment can have its own separate fire protection elements, such as one or more temperature sensors, one or more gas detectors, smoke detectors, or radiation detectors, and / or devices for controlling or shutting down equipment, and / or devices for releasing extinguishing agents or other fire-fighting agents. For example, in the event of a fire or after the detection of an increased fire risk, a fire compartment can be flooded with a fire-retardant gas, foam, or powder, or with a gas or other substance that displaces hydrogen. Furthermore, the fire protection elements can include means for ventilation or for controlling or blocking the ventilation of a fire compartment.

[0015] Temperature sensors can be based on various known measurement principles and can be designed, for example, as electronic components such as NTCs, semiconductor elements, or pyrometers. Such components can be installed, in particular, on the drive electric motor or in the secondary fire compartment, but also in the primary fire compartment and / or on the fuel cell. In this context, fire protection components are understood to include not only those that detect elevated temperature or a parameter conspicuous in the event of a fire, such as smoke development, but also detectors that indicate an increased fire risk associated with the drive system, such as detectors that signal an undesirable or hazardous hydrogen or oxygen concentration, or an unusual gas pressure or partial pressure development.This means that chemical processes that could lead to a fire can be detected early.

[0016] Each of the fire compartments, meaning in particular the first and second fire compartments, but also any further fire compartments mentioned in this text, can contain one or more of the aforementioned fire protection elements. This can be particularly useful if the gas compartments of the first and second fire compartments, and possibly any further fire compartments, are separated from each other. In this way, any detected signals indicating a fire or fire risk can be assigned to a specific fire compartment at an early stage.A common processing unit may be provided, which is connected to fire protection elements of different fire compartments and which assigns a specific fire situation or fire risk situation to a combination of signals or measured values ​​from different fire compartments, and on this basis determines an overall risk and signals it to a pilot of the aircraft and / or initiates certain countermeasures.

[0017] The drive unit can often include additional components, such as a cooling system that supplies the fuel cell with a cooling fluid, for example, a cooling gas or liquid. Such a cooling system can be located inside or outside the primary fire compartment. The cooling system can supply cooling air or hydrogen as the cooling medium. For example, it can draw hydrogen directly from the hydrogen tank or from a pressure regulator connected to the hydrogen tank, which in turn is connected to the fuel cell unit and reduces the pressure from the hydrogen tank. In such a pressure regulator, the pressure of the hydrogen gas is already reduced for use in the fuel cell unit, thus cooling the gas.

[0018] If the cooling unit is located in the first fire compartment, it can be monitored together with the fuel cell unit. If it is located outside the first fire compartment, fire risks from the cooling unit are not directly transferred to the fuel cell unit and vice versa.

[0019] An oxygen supply system for the fuel cell may be provided, either combined with or separate from the cooling system. This system provides a desired oxygen supply in the form of a gas flow with a specific volumetric flow rate at a specific pressure. Within the scope of this text, such an oxygen supply system may be designed as a supply system using ambient air or a gas consisting predominantly of oxygen. The air or gas supply may originate from a gas tank or directly from the environment, with or without a compression or pressure-reducing device. The oxygen flow is directed to the fuel cell and, for example, can be routed via an oxygen line through a fire-resistant wall of the first fire compartment to the fuel cell if the oxygen supply system is located outside the first fire compartment.The oxygen supply system can, for example, include a compressor and / or an oxygen tank from which oxygen can be supplied in the event of increased energy demand. The cooling system and the oxygen supply system can be jointly controlled by a control unit, since the required cooling and oxygen supply each depend, at least in part, on the operating state of the fuel cell system.

[0020] Individual or all components of the drive system, such as the motor, fuel cell unit, hydrogen tank, cooling system, oxygen supply unit, inverter, and battery, can be modular and individually replaceable. These elements can be mounted on a common support frame.

[0021] Fire-resistant walls can be designed as cuboids or polyhedra, or, to save space, as cylindrical enclosures. They can also have organic shapes, for example, if they are fire-retardant coated exterior cladding. Fire-resistant walls can have a multi-layered structure, combining highly insulating layers with layers of high heat capacity and / or layers that release fire-retardant substances. These layers can include metal, plastic, and / or ceramic. Combinations of metal and plastic, metal and ceramic, or plastic and ceramic layers can be advantageous.

[0022] Furthermore, a voltage regulator and an inverter for supplying electrical power to the drive motor can be provided, each of which can be located separately either inside or outside the second fire compartment. For example, the inverter can be located inside the second fire compartment to minimize the electrical cables to the drive motor, thereby reducing electrical losses and cable weight. The inverter can also be integrated directly with the motor. Alternatively, the inverter can be located inside the second fire compartment and the voltage regulator outside. In this case, the design flexibility allows for space-saving placement of the voltage regulator either between the first and second fire compartments or adjacent to them.In such a case, the voltage regulator can, for example, be located in the battery fire protection room.

[0023] The voltage regulator can be connected to an electrochemical, rechargeable battery that can be charged by the fuel cell and is available in the event of a fuel cell failure or can be activated in case of increased power demand. This battery can be located in the second fire compartment or in a separate battery fire compartment, which may be located inside or outside the second fire compartment. The battery fire compartment can be fully or partially enclosed by a battery fire wall, which may also be located entirely within a second fire wall. Power lines and fluid lines can pass through the fire walls using fire-resistant penetrations, such as those with ceramic bushings.

[0024] One design of a drive system may, for example, provide that all units, containers and lines of the drive system intended for carrying hydrogen are completely located within the first fire protection room and / or surrounded by the first fire protection wall.

[0025] In this case, a hydrogen tank for liquid or gaseous hydrogen can also be located in the first fire protection room and be completely or partially surrounded by the first fire protection wall.

[0026] The first fire compartment and / or the space enclosed by the first fire wall may have a ventilation opening into which a purge gas, such as ambient air, can be introduced to displace any hydrogen that may have escaped or to expel it from the first fire compartment. For this purpose, a gas exhaust opening may also be provided on the first fire compartment and / or the first fire wall. The ventilation / inlet opening and / or the exhaust opening may each be open and closeable by means of a closing device. The ventilation opening may be pressurized by dynamic pressure generated during aircraft movement or by airflow to introduce air into the first fire compartment.Similarly, a gas flow generated by the airflow can be used to create a negative pressure at an outlet opening using the Bernoulli effect, thereby generating a gas flow through the first fire protection space.

[0027] If a hydrogen tank is located in the first fire compartment, all hydrogen lines between it and the fuel cell unit can be kept very short to minimize leaks and escaping hydrogen, and to reduce weight by shortening the lines. A valve / filling device can be provided directly at the hydrogen tank for refueling, allowing a flexible tank line to be connected directly. In this case, a lockable tank opening can be provided in the first fire wall through which the refueling line can be routed. Alternatively, a fixed tank line can be installed in the first fire compartment, running from the hydrogen tank to the first fire wall and passing through it in a sealed manner.It is also conceivable that the hydrogen tank, in the area of ​​a tank valve directly attached to it, abuts the first fire wall, or that part of the hydrogen tank protrudes from or through the first fire compartment. In this case, a tank valve can be provided on the hydrogen tank in the area that protrudes from the first fire wall.

[0028] With the aforementioned concept, it is possible to allow hydrogen gas escaping from pipes or containers, from a tank, or from the fuel cell system to drain away or be actively flushed away. Particularly when the aircraft is stationary, a motor-driven fan can be provided in the area of ​​the ventilation opening and / or at the exhaust opening. Alternatively or additionally, it can also be provided that at least the ventilation opening and / or the exhaust opening is / are located in the upper half or at the top, or even at the highest point, of the first fire compartment or a space enclosed by the first fire wall, so that escaping hydrogen gas can at least be forced out through one of the two openings by its own buoyancy.For this purpose, it may be provided, for example, that both the ventilation opening and / or the exhaust opening are forcibly opened by a spring mechanism in the event of a failure of all electrical systems.

[0029] If the first fire compartment also contains one or the only hydrogen tank, the fuel cell, the hydrogen tank, and the drive electric motor of the propulsion system can be arranged in a row in the direction of flight and / or in the direction of the motor's drive axis. The motor's drive axis can also be arranged vertically and perpendicular to the direction of flight.

[0030] Another embodiment of a propulsion system may provide that at least one hydrogen tank, which can be connected to or is connected to the fuel cell system, is arranged in a third fire protection space, in particular in a wing.

[0031] In this case, for example, the third fire compartment can be at least partially surrounded by a third fire wall. This third fire wall can then be formed, for example, entirely or partially by the upper and / or lower skin of a wing or by additional walls within the wing. In any case, the third fire wall can have a fire-retardant coating, such as a special paint, or a coating that releases a fire-retardant or fire-inhibiting substance in the event of a fire.

[0032] The third fire compartment can also be located in a straight line with the first and second fire compartments. The third fire compartment can then be connected to the first fire compartment, or it can be separate from it. In the former case, the first and third fire compartments can be ventilated together. In the latter case, the first and third fire compartments can have different fire protection elements, such as different detectors and different fire protection concepts. For example, the third fire compartment can be ventilated solely through an exhaust vent due to the buoyancy of the hydrogen gas, while the first fire compartment has active ventilation, including a fan. The exhaust vent of the third fire compartment can advantageously be located at its top to allow the hydrogen to escape.

[0033] As mentioned above, the fuel cell unit can also be positioned between the propulsion electric motor and the hydrogen tank, viewed from the direction of travel of the propulsion electric motor and / or from the direction of flight of the aircraft. In this case, the propulsion unit can be manufactured particularly well as a clearly structured modular assembly and installed in an aircraft. With such a design, the individual modules can also be easily replaced and maintained separately.

[0034] Furthermore, it may be provided that power lines carrying the propulsion current, viewed in the direction of the propulsion axis and / or in the direction of flight of the aircraft, run exclusively in a length section of the propulsion system that extends from the fuel cell to and including the propulsion electric motor.

[0035] In this way, the electrical conductors that carry / transport the drive power and therefore must have a certain minimum cross-section can also be kept particularly short to save weight and reduce electrical resistance.

[0036] Between the fuel cell unit and the drive electric motor, the cables may also be connected to a voltage regulator and an inverter, which may also be located within the aforementioned length. The voltage regulator may also be connected to a battery. The voltage regulator and / or the inverter may be located either inside or outside the second fire compartment and / or inside or outside the second fire wall.

[0037] A particular embodiment may further provide that the first fire protection compartment and the second fire protection compartment are arranged one behind the other in the direction of view of the drive axis of the drive electric motor and / or in the direction of flight of the aircraft and / or that the first fire protection compartment is divided by a fire protection partition wall, wherein the fuel cell device is arranged on a first side of the fire protection partition wall and a hydrogen tank is arranged on a second side of the fire protection partition wall.

[0038] If the first fire compartment is divided by a fire-resistant partition, the ventilation system can, for example, ventilate both separated areas of the first fire compartment in parallel or sequentially. For this purpose, the two areas of the first fire compartment can be connected to each other by at least one ventilation opening or duct. In this case, sensors, such as hydrogen detectors or fire sensors, can also monitor both parts simultaneously.

[0039] It may also be provided that the first fire wall is identical to the second fire wall in at least one section, or that the two fire walls are directly adjacent to each other in one section.

[0040] This design allows for a space-saving and weight-saving construction of the first and second fire compartments. Furthermore, the firewalls of the first and second fire compartments can be mechanically connected in this way and, for example, also form a load-bearing unit for the drive unit. Additional components of the drive unit, such as a voltage regulator, an inverter, or a battery, can then be located next to the first and second fire compartments and, for example, attached to the outside of a first or second firewall.

[0041] Another embodiment of a drive unit may provide that it has a cooling unit for supplying the fuel cell unit with a cooling medium and an oxygen unit for supplying the fuel cell unit with oxygen, which are arranged in particular inside or outside the first and second fire protection rooms.

[0042] It may also be provided that the drive unit has a voltage control device for regulating the supply voltage of the drive electric motor, which is located within the first fire protection space or outside the first and second fire protection spaces, in particular in the direction of view of a drive axis of the drive electric motor or in the direction of flight, between them.

[0043] Furthermore, it is possible to stipulate that the first fire protection room has at least one fire sensor and / or one hydrogen sensor for the detection of hydrogen and / or that the second fire protection room has a temperature sensor and / or one fire sensor.

[0044] A fire sensor can be configured to detect specific gases or smoke, or radiation such as light. A temperature sensor can be located in the second fire compartment, either directly connected to the drive motor or separately and at a distance. If the temperature sensor is directly connected to the drive motor, it can detect temperature increases very quickly; however, this can lead to false alarms if the temperature increase is only localized. If the temperature sensor is at a distance from the drive motor, it detects an average temperature with a certain time delay and can thus better detect general overload conditions or other damage, such as damage to the electrical insulation of the motor winding or to supply lines.

[0045] Another embodiment of the drive system can provide for an electrochemical, rechargeable energy storage device, which is either located outside the first and second fire compartments and completely enclosed by a third fire wall / battery fire wall, or which is located inside the second fire compartment. The rechargeable energy storage device, also called a battery, can be charged by the fuel cell system via a voltage regulator during normal operation or during phases in which only low motor power is required, in order to power the drive motor together with the fuel cell when high power is required.

[0046] Furthermore, it may be provided that the first fire protection room has a ventilation device with an inlet opening and an outlet opening, wherein at least one device for generating a pressure gradient between the inlet opening and the outlet opening is provided.

[0047] The configuration of the device for generating a pressure differential to introduce a purge gas into the first fire compartment and purge hydrogen has already been described above. It may also be provided that a control device for regulating the pressure differential generation device is provided depending on a temperature and / or a hydrogen gas concentration in the first fire compartment, wherein the control device is connected to at least one temperature sensor and / or one hydrogen sensor located within the first fire compartment.

[0048] This control device can be connected to sensors for detecting the temperature and / or hydrogen gas concentration in the first fire protection room, or to a device for determining the movement or speed of the aircraft, and can control the ventilation of the first fire protection room depending on these parameters.

[0049] This ensures, for example, that the first fire compartment is ventilated by an active, motor-driven ventilation system when the aircraft is stationary. Furthermore, filling the hydrogen tank often results in a temperature increase, which is detected by a temperature sensor located on the hydrogen tank, whereupon the ventilation is activated or intensified. Alternatively, a detector can be provided that automatically generates a signal, either mechanically or electrically, when a fuel line is connected to the hydrogen tank's filling point, triggering the activation of the active ventilation.

[0050] It may also be provided that a first fire protection wall, at least partially surrounding the first fire protection room, is penetrated by a filling device for filling the hydrogen tank.

[0051] Ultimately, the invention relates not only to a propulsion system of the type described above, but also to an aircraft with at least two propulsion systems of the type described, wherein, in particular, both drive electric motors are electrically connected or connectable to both fuel cell systems and / or, in particular, both fuel cell systems are connected or connectable to two hydrogen tanks each by means of hydrogen lines. The invention is illustrated below with reference to exemplary embodiments in the figures of a drawing and subsequently explained.

[0052] This shows:

[0053] Figure 1: a schematic representation of an aircraft with a propulsion system,

[0054] Figure 2: a schematic representation of an aircraft with a vertical drive axis and a drive unit,

[0055] Figure 3: schematically a first embodiment of a drive device with two fire protection rooms and fire protection walls open on one side each,

[0056] Figure 4: schematically shows a second embodiment of a drive device with two fire protection rooms and closed fire protection walls,

[0057] Figure 5: another embodiment of a drive device, Figure 6: an embodiment of a drive device with three fire protection rooms and each with closed fire protection walls, as well as

[0058] Figure 7: an aircraft with multiple propulsion systems.

[0059] Figure 1 shows an aircraft 2 with a propulsion unit 1 that drives a propeller 6. The propulsion unit can be configured as shown in detail in the subsequent figures. Figure 1 also shows two wings 11a, 11b, each containing a hydrogen tank 4a, 4b. For this purpose, fire compartments can be formed within the wings, indicated by the dashed lines, which are equipped with fire protection elements such as hydrogen / gas sensors and / or fire sensors and / or firewalls. Firewalls can be formed, for example, by a fire-resistant coating or paint on the wing skins. The direction of flight of the aircraft is indicated in Figure 1, as in the other figures, by a directional arrow labeled 12.

[0060] Figure 2 shows an aircraft with a propulsion unit 1, where the drive axis 7 for driving the propeller 6 is oriented vertically, similar to a helicopter. The direction of flight and the drive axis are therefore not aligned. If, for example, the fuel cell unit and the drive motor are arranged one behind the other on a single axis, this axis can also run vertically, in contrast to the embodiment in Figure 1, where it runs horizontally. A hydrogen tank, labeled 4 in Figure 2, can lie with its longitudinal axis on this axis or, for example, perpendicular to it.

[0061] Figure 3 schematically depicts a first embodiment of a drive unit 1 with two fire compartments 8, 9 and firewalls 8a, 9a, each open on one side. Such a drive unit, like the variants shown in the other figures, can be used in aircraft, but also in propeller-driven means of transport such as boats, ships, and other vehicles. This example is intended to show that while the firewalls can completely surround the fire compartments, they do not necessarily have to. In the example shown, the second firewall 8a is open to the front in the direction of flight and closed to the first fire compartment 9. The first firewall 9a is open to the rear towards the aft end of the aircraft, while it closes off and seals off the first fire compartment from the front, separating it from the second fire compartment.This particularly prevents or hinders the spread of a fire between the first and second fire protection rooms.

[0062] A fuel cell unit 3 is located in the first fire compartment 9. The first fire compartment 9 has a ventilation unit 19a, 19b, 19c, 19d with an inlet opening 19a and an outlet opening 19b, and additionally a device for generating a pressure gradient between the inlet opening and the outlet opening is provided, which may, for example, include an electric fan in the inlet opening and / or in the outlet opening. An example is further explained below showing that the device for generating a pressure gradient can also be actively controlled based on measured values.

[0063] In the second fire compartment 8, a drive electric motor 5 is shown, which is powered by an electronic converter 5a, also located in the second fire compartment. However, the converter can also be located outside the fire compartments to be easily accessible, for example for maintenance or repairs.

[0064] Figure 3 further shows a battery 18, which in this case is located outside the first and second fire protection rooms, but in its own battery fire protection room, which is surrounded by a fourth fire protection wall 18a, also called a battery fire protection wall.

[0065] As shown in Figure 4, the battery can also be arranged with or without a fourth fire-resistant wall within the second fire compartment. Reference numeral 15 denotes a voltage regulator that is electrically inserted between and connected to the inverter 5a and the fuel cell unit 3. The battery 18 is connected to the voltage regulator, which controls the charging of the battery as well as the withdrawal of electrical energy from the battery and coordinates this with the supply of electrical energy from the fuel cell unit 3 to the inverter.

[0066] As shown in Figure 3, a hydrogen tank 4 is located outside the fire compartments, specifically outside the first fire compartment. Hydrogen escaping through the wall of the hydrogen tank can thus easily dissipate without accumulating in an enclosed space. The drive unit incorporates various sensors that can be connected to different fire protection devices, alarms, and fire suppression control systems.

[0067] For example, a fire sensor 20g, which can be configured as a temperature sensor, smoke sensor, or gas sensor, is arranged on the drive motor 5. A temperature sensor, smoke sensor, or gas sensor 20f can also be provided on the inverter. Alternatively, the second fire compartment 8 can be monitored by a temperature sensor, smoke sensor, or gas sensor. In the first fire compartment 9, for example, a gas sensor, in particular a hydrogen sensor 20c, can be provided. This can be designed as a simple detection sensor and respond when a detection threshold is exceeded, or it can detect a gas concentration and transmit it via electrical signals to a control unit, which can, for example, issue an alarm and / or initiate or control active ventilation of the first fire compartment by means of the ventilation device 19a, 19b, 19c, 19d with regard to the ventilation intensity.For example, a smoke sensor or temperature sensor can also be provided in the first fire protection room 9.

[0068] The hydrogen tank 4 has a tank / filling device which can be monitored for 20 hours by means of a gas sensor / hydrogen sensor attached to it.

[0069] Figure 4 schematically illustrates a second embodiment of a drive unit with two fire compartments and closed firewalls. In contrast to the drive unit shown in Figure 3, according to Figure 4, the first and second fire compartments 8 and 9 are each completely enclosed by a firewall 8a and 9a, respectively. However, the firewall enclosure may leave small openings for gas exchange and for the passage of electrical and fluid lines, so the firewalls do not need to be hermetically gas-tight. Reliable fire resistance is essential.In contrast to the drive unit shown in Figure 3, according to Figure 4 the battery 18 is arranged in its own battery fire compartment 18a within the second fire compartment and the second fire wall 8a, the battery fire compartment being enclosed by a fourth fire wall 18a, also called the battery fire wall. This prevents a fire or overheating of the battery from spreading to the second fire compartment outside the battery fire compartment. In addition to the battery, the voltage regulator 15 is also located in the second fire compartment. The fire sensor 20g, which can be configured as a temperature sensor, smoke sensor, or gas sensor, can monitor the entire second fire compartment. The battery fire compartment can also have its own temperature sensor, smoke sensor, or gas sensor.A temperature sensor, smoke sensor, or gas sensor may also be provided on the inverter and / or in the battery fire compartment. The cooling unit 13 for supplying the fuel cell unit 3 with a cooling medium and the oxygen unit 14 for supplying the fuel cell unit with oxygen may be located outside the first fire compartment 9 in such a drive unit, but also, as shown in the example of Figure 4, inside the first fire compartment 9. The first fire compartment may be equipped with a temperature sensor, smoke sensor, or gas sensor, or a combination of such sensors, which, in this case, can also monitor the cooling unit 13 and the oxygen unit 14 in addition to the fuel cell unit.

[0070] In each of the aforementioned cases, the cooling unit 13 is connected to the fuel cell unit via fluid lines and supplies it with a cooling fluid, for example, a coolant or a gas, such as hydrogen. The cooling unit and the fuel cell unit can also be connected to a common cooling circuit for this purpose. However, it is also possible to cool the fuel cell unit using the cooling unit with expanded and thus cooled hydrogen gas from a hydrogen tank. An oxygen unit 14 is provided to supply the fuel cell unit 3 with oxygen, which supplies the fuel cell unit with oxygen gas via a fluid line; this oxygen gas can also be compressed. The oxygen unit can also include a compressor for this purpose.

[0071] Oxygen supply is particularly necessary in an intensive form and possibly under increased pressure during phases in which the fuel cell system is required to provide high performance, such as during the takeoff of an aircraft.

[0072] As with the drive device shown in Figure 3, a ventilation device 19a, 19b with an inlet opening 19a and an outlet opening 19b is also provided in the first fire protection room 9 according to Figure 4, wherein an additional device for generating a pressure gradient between the inlet opening and the outlet opening is provided, which may for example include an electric blower in the inlet opening and / or the outlet opening.

[0073] The hydrogen tank 4, like the hydrogen tank shown in Figure 3, can be arranged on the drive axle 7 in a straight line with the drive motor 5 and the fuel cell device 3, and a longitudinal axis of the oxygen tank can also lie on this line or be aligned parallel to it.

[0074] However, Figure 4 clearly shows that a hydrogen tank 4c, 4d, depicted with dashed lines, can optionally be provided as an alternative or additional element to the hydrogen tank 4 and can be arranged offset and rotated relative to the drive axle 7. In particular, additional hydrogen tanks, which can be arranged, for example, in wings, are located away from the drive axle.

[0075] A gas sensor can be provided on the hydrogen tank 4, for example near the filling / refueling facility, which can signal the escape of hydrogen and emit alarm signals.

[0076] Figure 5 shows another embodiment of a drive unit in which two relatively large fire compartments 8 and 9 are provided, the first fire compartment 9 containing both a fuel cell unit 3 and a hydrogen tank 4. The first fire compartment is completely enclosed by the first fire wall 9a. The cooling unit 13 and the oxygen unit 14 are located outside the first fire compartment, but they can also be located inside this compartment. In the latter case, they could be monitored by the sensors provided in the first fire compartment and ventilated by the ventilation unit 19a, 19b, 19c, 19d.The ventilation device has one or more inlet openings 19, 19a and one or more outlet openings 19b, wherein a device 19c is provided for generating a pressure gradient between the inlet opening and the outlet opening in the form of an electric blower. Additionally, during the movement of the aircraft in the direction of flight, air is drawn into the inlet openings by the dynamic pressure, or gas is extracted from at least one outlet opening by means of air flowing past an outlet opening via the Bernoulli effect.

[0077] The activity of device 19c for generating a pressure gradient between the inlet and outlet openings is controlled by control device 19d. For this purpose, sensor 20c, which is wirelessly or via a cable connected to the control device, or one of sensors 20a or 20b, can send signals to the control device when certain temperature, hydrogen concentration, or gas concentration values ​​of another gas are exceeded, or when smoke is detected. Sensor 20c and / or one of sensors 20a or 20b can be configured as a hydrogen sensor that measures the concentration of hydrogen gas. Sensor 20b in the first fire compartment can, for example, also be configured as a temperature sensor that sends a signal to the control device to switch on or increase ventilation when a temperature threshold is exceeded. The control device then, for example, controls a fan in inlet opening 19c.

[0078] Sensor 20b can, for example, be sensitive to the heating of hydrogen tank 4 during filling. The temperature increase would initially be noticeable on the side of fire compartment 9 and on the side of fire-resistant partition 9b where hydrogen tank 4 is located. In such a case, ventilation 19, 19a, 19b, 19c, 19d can still ventilate the entire fire compartment 9, since fire-resistant partition 9b does not hermetically separate the two parts of this fire compartment.

[0079] Battery 18 is surrounded by its own battery fire protection wall 18a and is located outside the first and second fire protection walls.

[0080] The voltage regulator 15 is also located outside the first and second fire protection walls.

[0081] The voltage regulator 15, the battery 18, the oxygen supply unit 14, and the cooling unit 13 can be arranged together between the first and second fire compartments. The first and second firewalls 8, 9, as well as the voltage regulator 15, the battery 18, the oxygen supply unit 14, and the cooling unit 13, can be mounted together in a support frame 100, wherein at least the first and second firewalls can each be mounted separately to the support frame and can be detached from it independently. Furthermore, the battery and the voltage regulator can be mounted together or each element separately to the support frame 100. The support frame can be composed of several metal or plastic profiles that together form an elongated cage. This cage can, for example, have the shape of a cuboid.

[0082] The cooling unit and the oxygen unit can be combined with a drive control unit to form a single unit, which is attached to the support frame along with the aforementioned components. The drive control unit communicates wirelessly or via electrical signal lines with the described gas and temperature sensors in the fire compartments, as well as with the aircraft control system, which transmits the required power output. Based on the measured and / or transmitted parameters, the drive control unit determines the oxygen demand and the required cooling capacity and supplies the oxygen and coolant accordingly.

[0083] Figure 5 also shows a fire-resistant partition 9b, which divides the first fire compartment into two parts. This fire-resistant partition is optional and can therefore be omitted. For example, it can be partially gas-permeable to allow for common ventilation of the two parts of the first fire compartment.

[0084] Figure 6 shows an embodiment of a drive device with three fire protection rooms 8, 9, 10 and each with closed fire protection walls 8a, 9a, 10a.

[0085] In the first fire protection room 9, a fuel cell device 3, a cooling device 13 and an oxygen device 14 are arranged, as well as a sensor 20c and a sensor 20d, one of which can be designed as a gas sensor, in particular a hydrogen sensor, and one as a temperature sensor.

[0086] In the second fire compartment 8, a drive electric motor 5 and an inverter are arranged. This second fire compartment also has two sensors 20g, 20f, one of which can be configured as a gas sensor, smoke sensor, or radiation sensor, generally as a fire alarm sensor, and the other as a temperature sensor. However, both sensors 20g, 20f can also be configured as temperature sensors in order to monitor the temperature of the motor and the inverter separately.

[0087] The first fire wall 9a and the second fire wall 8a abut each other at their end faces around the drive axis 7. In this area, the two fire walls could also share a section of fire protection wall.

[0088] In addition to the first and second fire protection compartments 8, 9, a separate third fire protection compartment 10 is provided, which is surrounded by a third fire protection wall 10 and contains a hydrogen tank 4. The third fire protection compartment is ventilated by a ventilation device with one or more inlet openings 19, 19a and one or more outlet openings 19b, wherein a blower 19c is provided in the form of an electric blower to generate a pressure gradient between the inlet opening and the outlet opening.

[0089] The first fire protection room with the fuel cell equipment can also have a separate, similar ventilation system.

[0090] The three fire compartments 8, 9, 10 are arranged in a straight line one behind the other in such a way that they fit into a cage-like, elongated, cuboid support frame 100, as shown in Figure 5, and can each be mechanically connected to it separately. This allows the firewalls, which in each of the embodiments described above can be designed, for example, as cuboid boxes, to be individually assembled and replaced. The support frame with a drive unit can also be transported as a complete module and installed in an aircraft. The support frame then only needs to be connected to an aircraft chassis and, if necessary, to additional hydrogen tanks in the aircraft.

[0091] Figure 7 shows an aircraft 2 with wings 11a, 11b, each wing having an engine nacelle 25a, 25b. Each engine nacelle, of which there may be three or four in total, has a drive unit 1a, 1b. Each wing 11a, 11b also has a hydrogen tank 4a, 4b, located between the engine nacelle 25a, 25b and the fuselage 25c of the aircraft, within a fire compartment 26a, 26b. The fire compartments 26a, 26b may each be surrounded by a firewall. The firewalls may be formed by applying a fire-retardant coating, particularly on their inner surface, to the walls surrounding the hydrogen tanks, for example, the upper and lower wing skins. The fire-retardant coating may be, for example, a fire-retardant paint.

[0092] The respective fuel cell unit of each of the drive units aa, bb can be connected to both hydrogen tanks via fluid lines 27a, 27b, 27c, 27d to achieve redundancy in the hydrogen supply to the fuel cell units. Furthermore, the electrical line inputs of the drive electric motors or the converters of the two drive units, or the electrical power outputs of the two fuel cell units, can be interconnected by means of an electrical line 28 to ensure that, in the event of a failure of one fuel cell unit, both drive electric motors can be supplied with electrical energy by the other fuel cell unit.

[0093] Because the two or more drive units are identical in design, they are so compatible that sharing a hydrogen supply via a common tank or a common electrical power supply is easily possible. Spare parts management and repair are also facilitated by this modular and standardized design of the drive units.

Claims

APUS ZERO EMISSION GMBH 247 PCT 2709 Patent claims 1. Propulsion system (1) for a means of transport, in particular an aircraft (2), comprising a fuel cell system (3) which is connectable to a hydrogen tank (4, 4a, 4b, 4c, 4d) and to a drive electric motor (5) electrically connected to the fuel cell system, which is configured to drive a propeller (6) about a drive shaft (7), as well as comprising a first fire compartment (8) in which the fuel cell system and in particular a hydrogen tank is arranged, and comprising a first fire wall (8a) which completely or partially surrounds the first fire compartment, as well as comprising a second fire compartment (9) in which at least the drive electric motor is arranged, and comprising a second fire wall (9a) which completely or partially surrounds the second fire compartment.wherein the first and the second fire-resistant walls are at least partially different from each other and wherein the first fire-resistant room is separated from the second fire-resistant room by at least one fire-resistant wall.

2. Drive unit according to claim 1, characterized in that all units, containers and lines (3, 4) of the drive unit (1) intended for carrying hydrogen are arranged completely within the first fire protection room (8) and / or are surrounded by the first fire protection wall (8a).

3. Drive device according to claim 1, characterized in that at least one hydrogen tank (4, 4a, 4b, 4c, 4d) connected to the fuel cell device (3) is arranged in a third fire protection space (10), in particular in a wing (11a, 11b). TI 4. Drive unit according to one of claims 1 to 3, characterized in that the fuel cell unit (3) is arranged between the drive electric motor and the hydrogen tank when viewed in the direction of travel of a drive axis of the drive electric motor and / or when viewed in the direction of flight of the aircraft.

5. Drive unit according to one of claims 1 to 4, characterized in that power lines carrying the drive current run exclusively in a longitudinal section of the drive unit which extends from the fuel cell (3) to and including the drive electric motor (5) when viewed in the direction of the drive axis (7) and / or in the direction of flight (12) of the aircraft.

6. Drive unit according to one of claims 1 to 5, characterized in that the first fire protection compartment (8) and the second fire protection compartment (9) are arranged one behind the other in the direction of view of the drive axis (7) of the drive electric motor (5) and / or in the direction of flight (12) of the aircraft (2) and / or that the first fire protection compartment is divided by a fire protection partition (8b), wherein the fuel cell unit (3) is arranged on a first side of the fire protection partition (8b) and a hydrogen tank (4) is arranged on a second side of the fire protection partition (8b).

7. Drive device according to one of claims 1 to 6, characterized in that the first fire protection wall (8) is identical to the second fire protection wall (9) in at least one section or that the two fire protection walls are directly adjacent to each other in one section.

8. Drive device according to one of claims 1 to 7, characterized in that it has a cooling device (13) for supplying the fuel cell device with a cooling medium and an oxygen device (14) for supplying the fuel cell device with oxygen, which are arranged in particular inside or outside the first and the second fire protection room.

9. Drive device according to one of claims 1 to 8, characterized in that it has a voltage control device (15) for regulating the supply voltage of the drive electric motor (5), which is located within the first fire protection room (8) or outside the first and the second fire protection room (8, 9), in particular between them when viewed in the direction of a drive axis (7) of the drive electric motor.

10. Drive device according to one of claims 1 to 9, characterized in that the first fire protection room (8) has at least one fire sensor (20g) and / or one hydrogen sensor (20f) for detecting hydrogen and / or that the second fire protection room (9) has a temperature sensor (20c) and / or one fire sensor (20d).

11. Drive device according to one of claims 1 to 10, characterized in that an electrochemical rechargeable energy storage device (18) is provided, which is either located outside the first and second fire protection rooms (8, 9) and is completely surrounded by a fourth fire protection wall (18a), or which is arranged inside the second fire protection room.

12. Drive device according to one of claims 1 to 11, characterized in that the first fire protection room (8) has a ventilation device (19a, 19b, 19c, 19d) with an inlet opening (19a) and an outlet opening (19b), wherein at least one device (19c) is provided for generating a pressure gradient between the inlet opening and the outlet opening.

13. Drive device according to claim 12, characterized in that a control device (19d) is provided for controlling the device (19c) for generating a pressure gradient as a function of a temperature and / or a hydrogen gas concentration in the first fire protection room (8), wherein the control device is connected to a is connected to a temperature sensor (20a) and / or a hydrogen sensor (20b), which are located within the first fire protection room.

14. Drive device according to one of claims 1 to 13, characterized in that a first fire protection wall (8a) at least partially surrounding the first fire protection room (8) is penetrated by a filling device (21) for filling the hydrogen tank (4).

15. Aircraft with at least two propulsion devices according to one of claims 1 to 14, wherein in particular both propulsion electric motors (5, 5a) are each electrically connected or connectable to both fuel cell devices (3, 3a) and / or in particular both fuel cell devices are connected or connectable to two hydrogen tanks (4, 4a) by means of hydrogen lines (22).

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