AUXILIARY DRIVE SYSTEM OF A TREE OF A PROPULSION SYSTEM OF A HELICOPTER

1. Technical Field of the Invention

The invention relates to an auxiliary drive system of a shaft of a propulsion system of a helicopter. Such an auxiliary system is for example designed to provide timely mechanical power to reactivate a turbine engine idle or to assist a maneuver autorotation of a single-engine helicopter or to provide an additional point propulsive power or to attend a multi helicopter engines whose engine is not operational (situation known by the acronym for OEI one engine inoperative). The invention also relates to a helicopter equipped with such an auxiliary mechanical drive system.

2. BACKGROUND

There are many situations during a flight helicopter

(Single-engine or multi-engine) as a one-off mechanical power is necessary to secure the flight.

For example, it has already been proposed by the applicant in the application FR3019588 a mechanical assist device for a propulsion system of a single-engine helicopter to deliver punctually, from a gas generator solid propellant, power propellant directly to the helicopter's rotor during an autorotation. This solution allows to overcome a failure of the turbine engine by providing an extra mechanical power to the helicopter for the reliable operation of autorotation in case of failure of the turbine engine.

This solution seems promising, but requires a significant amount of propellant onboard engine area. In addition, the pyrotechnic system is not closed, it participates in the emission of gases ejected to outside the system. This significant amount of propellant can be difficult especially

concerning the regulation transport.

It has also been proposed by the applicant in application FR 3019221 a hydraulic device for emergency start of a turbine engine to provide, via hydraulic, mechanical power of starting a turbine engine.

This solution is promising, but the bulk of the system could cause some problems for integration in some helicopters.

The inventors have sought to provide a solution for providing timely mechanical power at least one shaft of a propulsion system of a helicopter, this tree can be a shaft of a power transmission gearbox, or a tree a turbine, and generally any shaft connected directly or indirectly to the helicopter rotor.

The inventors in particular sought to offer a new solution to promptly provide mechanical power to a propulsion system of a helicopter that meets the criteria of lightness and compactness.

3. Objectives of the invention

The invention aims to provide an auxiliary drive system for rotation of a shaft of a propulsion system of a helicopter.

The invention also aims to provide, in at least one embodiment, an auxiliary drive system to rotate with a shaft of a propulsion system for a helicopter which is compact.

The invention also aims to provide, in at least one embodiment, an auxiliary drive system to rotate with a shaft of a propulsion system for a helicopter which is lightweight.

The invention also aims to provide, in at least one embodiment, an auxiliary drive system to rotate with a shaft of a propulsion system for a helicopter that can be certified for different types of helicopters (single engine, twin-engine, three-engined particular) and to address various mechanical failures.

The invention also aims to provide, in at least one embodiment, an auxiliary drive system rotating a shaft of a propulsion system of a helicopter that can be manufactured at costs compatible with profitability targets and optimization of expenses. The invention also aims to provide a helicopter with an auxiliary system according to the invention.

4. Summary of the Invention

To do this, the invention concerns an auxiliary drive system in rotation with a shaft, said shaft relay, of a propulsion system of a helicopter comprising at least one turbine connected to a power transmission gearbox adapted to drive rotating a rotor of the helicopter, said system comprising:

- a hydraulic motor mechanically connected to said relay shaft and adapted to be able to rotate,

- a hydraulic circuit liquid supply pressure of said hydraulic motor,

- a hydraulic valve rapidly controlled opening arranged on the hydraulic circuit and adapted to be placed on order at least in an open position in which liquid can power said hydraulic motor to allow rotating said relay shaft, or in a closed position wherein said hydraulic motor is no longer supplied with pressurized liquid.

An auxiliary system according to the invention is characterized in that said system further comprises a pyro-hydraulic storage device controlled by a control unit and connected to said hydraulic valve of said hydraulic circuit through a liquid supply line, said storer pyro- hydraulic comprising:

- a chamber comprising a piston delimiting two watertight compartments, a main compartment comprising at least a solid propellant cartridge, and a liquid storage chamber opening into said liquid supply line,

- an ignition charge connected to said main compartment and adapted to initiate combustion of at least one cartridge

solid propellant on command of said control unit.

A system according to the invention therefore comprises a storer pyrohydraulique - including the hydraulic part is completely independent of the helicopter preferably hydraulic network - which allows to pressurize liquid to a hydraulic circuit connected to a hydraulic drive motor rotating a shaft relay of a propulsion system of a helicopter.

Pyro-storer hydraulic system according to the invention comprises a small gas generator which is formed by at least a solid propellant cartridge. Once lit, the gas produced by the cartridge applies a pressure on the piston of the chamber, thereby pressurizing the liquid from the liquid reservoir. This liquid is expelled towards the hydraulic motor through the supply of the hydraulic circuit and the hydraulic circuit line, thereby rotating the relay shaft mechanically connected to the hydraulic motor.

The hydraulic motor of the liquid supply is effected by the cooperation of the pyro-hydraulic storer and a quick opening valve controlled.

The pyro-hydraulic storage device of a system according to the invention combines the advantages of a pyrotechnic solution and the advantages of a hydraulic solution, without however having to bear the disadvantages.

In particular, the system according to the invention takes advantage of both the energy density of a pyrotechnic solution (through the main compartment accommodating the solid propellant cartridges) and the power of a hydraulic solution density (through the second compartment liquid reservoir).

A system according to the invention can be independent of both the power grid of the helicopter and the hydraulic system. In particular, no storage battery of electrical energy is required. In addition, one or more solid propellant cartridges are sufficient to ensure the rotation of the relay shaft. The proposed solution makes it possible to provide power

mechanical booster without generating problems of space, weight and cost.

Its small footprint allows integration of the system in an engine compartment.

Moreover, a system according to the invention is simple to use and can be tested on the bench before integration on a helicopter.

A system according to the invention also allows to deliver a constant torque, which facilitates its integration in a helicopter architecture.

A system according to the invention showed no pressure continuously elements. Moreover, once ignited charge and the system is activated, the released gas remains confined in a closed volume, which facilitates the rankings transportation, implementation and certification of the object.

Advantageously and according to the invention, said main compartment of said enclosure of said pyro -Hydraulic storer comprises at least two solid propellant cartridges.

In this variant, at least two solid propellant cartridges are used in the main compartment to generate more pressure upon activation of the ignition charge. This allows for example to cause relay trees require a couple to the large boot.

Advantageously and according to the invention, said enclosure comprises a sealing membrane arranged between the solid propellant cartridges and said piston.

This waterproof membrane is intended to ensure the seal between the two compartments of the enclosure.

Advantageously and according to the invention, said piston is a differential piston sections configured to compress the liquid from said liquid storage compartment at a different pressure of the gas pressure of the main compartment.

According to this variant, the printed liquid pressure of the liquid reservoir is different from the pressure of the gas released by the ignition of the solid propellant cartridge. This allows to adjust the torque delivered to the relay shaft.

Advantageously, a system according to the invention comprises a tarpaulin

recovering liquid connected to said hydraulic motor through a purge valve.

The assembly formed of the sheet recovery and the purge valve allows expulsion of the hydraulic liquid when the liquid pressure in the circuit exceeds a predetermined threshold, and recovery of the liquid expelled into the collecting tank. The purge valve sets the predetermined threshold at which the liquid is expelled from the hydraulic circuit.

Advantageously, a system according to the invention comprises at least one free wheel carried by said relay shaft.

The presence of the free wheel prevents a spontaneous driving the hydraulic motor by the relay shaft.

Alternatively, the relay shaft carrying a freewheel is a shaft of an accessory box of a turbine engine.

A box of a gas turbine engine accessory drive permits the easement needed to operate the turbine of the gas generator and the helicopter equipment, such as air conditioning devices. According to this variant, the hydraulic motor is directly integrated on the accessory box, which allows on one hand to facilitate its installation and interconnection with the gas generator of the turbine engine, and secondly, to provide, if necessary, a part of the power required for driving easement and / or feeding helicopter equipment.

Advantageously and according to the invention, said relay shaft is a shaft of said power transmission gearbox so that the system can support system office in an autorotation of a single-engine helicopter.

In this embodiment, the auxiliary system is used to provide mechanical power directly to the power transmission box when necessary. Such a system is therefore particularly suitable for mechanically assist the helicopter during an autorotation, especially in the last phases of flight.

The use of a system according to this embodiment allows more reliable flights in a helicopter autorotation and thus significantly improve the landing rate without damage requiring a long immobilization of the helicopter.

Advantageously and according to the invention, said relay shaft is a shaft of a turbine engine of the propulsion system so that the system can act as this turbine engine reactivation system.

In this embodiment, the auxiliary system is designed to equip a multi-engined helicopter comprising turbine connected to a power transmission gearbox, of which at least one turbine of said turbine engine, said hybrid turbine engine is operable in at least one standby system during a steady flight of the helicopter, the other turbine operating alone during this steady flight.

A hybrid gas turbine engine is a gas turbine engine configured to be put on command and intentionally, in at least one predetermined standby system, from which it can exit normal or fast (also known as urgent). A gas turbine engine can not be in standby than in a steady flight of the helicopter, that is to say, out failure of a turbine engine helicopter, during a cruising flight situation , when operating under normal conditions. The output of the standby system is to pass the gas turbine engine in acceleration mode of the gas generator by a compatible drive with the output mode imposed by the conditions (normal standby output or output rapid sleep (also called emergency).

The auxiliary system according to the invention then ensures rapid reactivation of the turbine engine on standby if needed.

The invention also relates to a helicopter comprising a propulsion system, characterized in that it further comprises an auxiliary mechanical drive system of a shaft of said propulsion system of the invention.

The invention also relates to an auxiliary system and a helicopter equipped with such a system, characterized in combination by all or some of the features mentioned above or below.

5. List of Figures

Other objects, features and advantages of the invention will appear on reading the following description given by way of non-limiting and which refers to the appended figures in which:

- Figure 1 is a schematic view of an auxiliary system according to an embodiment of the invention used as rapid reactivation device for a gas turbine engine,

- Figure 2 is a diagrammatic view of a pyro-hydraulic storer of a system according to another embodiment of the invention,

- Figure 3 is a schematic view of a piston of a pyrohydraulique storer of a system according to another embodiment of the invention.

6. Description of an embodiment of the invention

In the figures, scales and proportions are not respected and that, for purposes of illustration and clarity.

Figure 1 is a schematic view of an auxiliary drive system for rotation with a shaft 8 relay according to the invention formed by a shaft of a gas turbine engine 6.

An auxiliary system according to this embodiment is thus intended to be able to ensure rapid reactivation of the turbojet engine 6.

The system according to the embodiment of Figure 1 comprises a 7 Hydraulic motor mechanically connected to the engine 6 via a freewheel. This hydraulic motor 7 may be a motor axial or radial pistons. Its function is to transform the hydraulic power that receives mechanical power for driving the startup or the reactivation of the turbine engine 6.

The hydraulic motor 7 is preferably mounted on the turbojet engine 6 by the bais of an accessory box, not shown in Figure 1.

The auxiliary system according to the invention also comprises a storage device 9 pyro -Hydraulic connected to the hydraulic motor 7 by means of a 10-hydraulic fluid supply pressure of the hydraulic motor 7. This hydraulic circuit 10 is itself supplied with liquid by a supply line 13 which connects the hydraulic circuit 10 and the storer 9 pyro-

hydraulic.

The feeding of the hydraulic motor 7 is dependent on a valve 1 1 Hydraulic quick opening, controlled, which is arranged on the hydraulic circuit 10 between the storage device 9 and the hydraulic motor 7.

This hydraulic valve 11 is controlled by a device controller 12, which is preferably the control computer 6 of the turbine engine, which further allows to define the gas turbine engine operating conditions.

When the valve 11 is controlled in opening, the liquid expelled from the storage device 9 is discharged to the hydraulic motor 7 so that the latter transforms the hydraulic power of the liquid received into a mechanical output power.

The auxiliary system also includes a 14 liquid collecting tank connected to the hydraulic motor 7 via a valve 15 to purge. This valve is calibrated such that the liquid is ejected from the circuit 10 as soon as the pressure exceeds a predetermined threshold.

The storer 9 pyro-hydraulic includes, according to the embodiment of Figure 1, an enclosure 20, a one-piece piston 16 housed within the enclosure and delimiting two compartments 17, 18 sealed variable volume. The compartment 17 accommodates a cartridge 19 in solid propellant and compartment 18 is a supply of fluid to variable volume. In the following, it is considered that the liquid compartment 18 and hydraulic system is oil.

The storer 9 also comprises a filler 25 suitable ignition to initiate combustion of the solid propellant cartridge 19 in order of the unit controller 12. Once lit, the gas produced by the cartridge 19 spreads into the compartment 17 and applies pressure to the piston 16 of the chamber, thereby pressurizing the oil 18 of the oil tank compartment. The oil is then expelled to the hydraulic motor 7 through the supply line 13 of the hydraulic circuit 10 and the hydraulic circuit 10 as such.

A system according to the invention therefore allows a one-time power input and can be used either to reactivate a turbine engine idle, or to be present a maneuver autorotation or to provide additional power

Instant propellant or attend a helicopter that lost the operation of one of its engines in the case of a twin-engine helicopter or tri-motored for example.

According to another embodiment not shown in the figures, the pyro-hydraulic storage device 9 comprises a plurality of cartridges 19 solid propellant housed in the compartment 17 of the enclosure 20.

Alternatively or in combination, and as shown in Figure 2, the stocker may include a waterproof membrane 23 arranged between the cartridge 19 to solid propellant and the piston 16. The waterproof membrane 23 is intended to ensure sealing between the two compartments of the enclosure. This membrane can be made of any type of impervious material.

In additional embodiment, the role of the piston can be held by a bladder which would provide the desired two major functions: movement of the volume and sealing between the two chambers.

According to another embodiment and as shown in Figure 3, the piston 16 is a piston differential sections configured to compress the liquid in the liquid storage compartment at a different pressure of the gas pressure of the main compartment. This allows to adjust the torque delivered to the relay shaft.

The system described in connection with Figure 1 is intended to ensure rapid reactivation of a turbine engine. However, the system of the invention can be implemented for rotating all shaft of a propulsion system of a helicopter, such as a shaft of a power transmission gearbox of the helicopter, a shaft an accessory box, a shaft of a gas generator of a turbine engine or a shaft of a free turbine of a turbine engine. In general, the system of the invention can participate in rotating, at the request and when necessary, any type shaft of a propulsion system. The skilled person can easily make necessary changes to the above description in connection with a turbine engine to ensure the

CLAIMS

1. Auxiliary system mechanical drive of a shaft, said shaft (8) relays, of a propulsion system of a helicopter comprising at least one turbine connected to a power transmission gearbox adapted for rotating a rotor the helicopter, said system comprising:

a motor (7) mechanically connected to said hydraulic shaft (8) relays and adapted to be able to rotate it, a circuit (10) hydraulic fluid supply pressure of said motor (7) hydraulic,

a valve (11) hydraulically-controlled quick-opening arranged on the circuit (10) hydraulically and adapted to be placed on order at least in an open position in which liquid can energizing said motor (7) hydraulically to allow rotating said shaft (8) relays, or in a closed position wherein said motor (7) hydraulic is no longer supplied with pressurized liquid,

characterized in that said system further comprises a storage device (9) pyrohydraulique controlled by a unit (12) for controlling and connected to said valve (11) of said hydraulic circuit (10) by a hydraulic line (13) of liquid supply said storage device (9) pyro -Hydraulic comprising:

an enclosure (20) comprising a piston (16) delimiting two watertight compartments, a compartment (17) principal comprising at least one cartridge (19) of solid propellant, and a compartment (18) opening fluid supply in said line (13 ) liquid supply,

a load (25) connected to said ignition chamber (17) main and adapted to initiate the combustion at least one cartridge (19) of solid propellant on said control unit

(12) command.

2. Auxiliary system according to claim 1, characterized in that said compartment (17) main of the said chamber (20) of said storage device (9) pyrohydraulique comprises at least two cartridges (19) of solid propellant.

3. Auxiliary system according to one of claims 1 or 2, characterized in that said enclosure (20) comprises a membrane (23) sealingly arranged between the cartridge (19) solid propellant and said piston (16).

4. System according to one of claims 1 to 3, characterized in that said piston (16) is a differential piston sections configured to compress the liquid from said liquid storage compartment to a pressure different from the pressure of the gas main compartment.

5. System according to one of claims 1 to 4, characterized in that it comprises a cover (14) liquid recovery connected to said motor (7) hydraulically via a valve (15) of purge.

6. System according to one of claims 1 to 5, characterized in that it comprises at least one free wheel carried by said relay shaft.

7. System according to one of claims 1 to 6, characterized in that said relay shaft is a shaft of said power transmission gearbox so that the system can support system office to a helicopter autorotation single engine.

8. System according to one of claims 1 to 6, characterized in that said relay shaft is a shaft of a turbine engine of the propulsion system so that the system can act as this turbine engine reactivation system.

9. Helicopter comprising a propulsion system, characterized in that it further comprises an auxiliary system mechanically drive a shaft of said propulsive system according to one of claims 1 to 8.