AUXILIARY SYSTEM FOR DRIVING A SHAFT OF A HELICOPTER PROPULSION SYSTEM

Abstract

The invention relates to an auxiliary system for mechanically driving a relay shaft (8) of a helicopter propulsion system, comprising: a hydraulic motor (7), mechanically connected to said relay shaft (8); a hydraulic circuit (10) for supplying a pressurised liquid to said hydraulic motor(7) a controlled, fast-opening hydraulic valve (11) arranged on the hydraulic circuit (10); a pyro-hydraulic storage unit (9) driven by a control unit (12) and connected to said hydraulic valve (11), said pyro-hydraulic storage unit (9)comprising: an enclosure (20) including a piston (16) that defines a main compartment (17) having at least one solid propellant cartridge (19) and a compartment (18) for a liquid supply; an ignition charge (25) connected to said main compartment (17) and suitable for initiating the combustion of at least one solid propellant cartridge (19) upon receiving a command from said control unit (12).

Claims

1. Auxiliary system for mechanically driving a shaft, called relay shaft, of a helicopter propulsion system comprising at least one turboshaft engine connected to a power transmission box adapted to drive in rotation a rotor of the helicopter, said system comprising: a hydraulic motor mechanically connected to said relay shaft and adapted to be able to drive it in rotation, a hydraulic circuit for supplying a pressurised liquid to said hydraulic motor, a controlled, fast-opening hydraulic valve arranged on the hydraulic circuit and adapted to be placed on command at least in one open position wherein the liquid can supply said hydraulic motor to enable a driving in rotation of said relay shaft, or in a closed position wherein said hydraulic motor is no longer supplied with pressurised liquid, wherein said system further comprises a pyro-hydraulic storage unit driven by a control unit and connected to said hydraulic valve of said hydraulic circuit by a liquid supply line, said pyro-hydraulic storage unit comprising: an enclosure comprising a piston that defines two sealed compartments, a main compartment comprising at least one solid propellant cartridge, and a compartment for a liquid reserve opening into said liquid supply line, an ignition charge connected to said main compartment and adapted to initiate the combustion of at least one solid propellant cartridge upon receiving a command from said control unit.

2. The auxiliary system according to claim 1, wherein said main compartment of said enclosure of said pyro-hydraulic storage unit comprises at least two solid propellant cartridges.

3. The auxiliary system according to claim 1, wherein said enclosure comprises a sealed membrane arranged between the solid propellant cartridges and said piston.

4. The system according to claim 1, wherein said piston is a differential section piston configured to be able to compress the liquid from said compartment for a liquid reserve at a pressure different from the pressure of the gas of the main compartment.

5. The system according to claim 1, wherein it comprises a tarpaulin for liquid recovery connected to said hydraulic motor by means of a drainage valve.

6. The system according to claim 1, wherein it comprises at least one freewheel carried by said relay shaft.

7.-9. (canceled)

10. The system according to claim 1, wherein said relay shaft is a shaft of said power transmission box so that the system can act as an assistance system for an autorotation of a single-engine helicopter.

11. The system according to claim 1, wherein said relay shaft is a shaft of a turboshaft engine of the propulsion system so that the system can act as a reactivation system of this turboshaft engine.

12. Helicopter comprising a propulsion system, wherein it further comprises an auxiliary system according to claim 1 for mechanically driving the shaft of said propulsion system.

Description

5. LIST OF FIGURES

[0052] Other aims, characteristics and advantages of the invention will appear upon reading the following description given only in a non-limiting manner, and which refers to the appended figures, wherein:

[0053] FIG. 1 is a schematic view of an auxiliary system according to an embodiment of the invention used as a device for quickly reactivating a turboshaft engine,

[0054] FIG. 2 is a schematic view of a pyro-hydraulic storage unit of a system according to another embodiment of the invention,

[0055] FIG. 3 is a schematic view of a piston of a pyro-hydraulic storage unit of a system according to another embodiment of the invention.

6. DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

[0056] In the figures, the scales and proportions are not respected and this, for purposes of illustration and clarity.

[0057] FIG. 1 is a schematic view of an auxiliary system for driving in rotation a relay shaft 8 according to the invention formed by a shaft of a turboshaft engine 6.

[0058] The auxiliary system according to this embodiment is therefore destined to be able to ensure the quick reactivation of the turboshaft engine 6.

[0059] The system according to the embodiment of FIG. 1 comprises a hydraulic motor 7 mechanically connected to the turboshaft engine 6 by means of a freewheel. This hydraulic motor 7 can be a motor with axial or radial pistons. It has the function of transforming the hydraulic power it receives in a mechanical power allowing to drive the starting or the reactivation of the turboshaft engine 6.

[0060] This hydraulic motor 7 is preferably mounted on the turboshaft engine 6 by means of an accessory box, not represented in FIG. 1.

[0061] The auxiliary system according to the invention also comprises a pyro-hydraulic storage unit 9 connected to the hydraulic motor 7 by means of a hydraulic circuit 10 for supplying a pressurised liquid to this 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 pyro-hydraulic storage unit 9.

[0062] The supply of the hydraulic motor 7 is dependent on a controlled, fast-opening hydraulic valve 11, which is arranged on the hydraulic circuit 10 between the storage unit 9 and the hydraulic motor 7.

[0063] This hydraulic valve 11 is controlled by a control device 12, which is preferably the control computer of the turboshaft engine 6, which further allows to define the operating regime of the turboshaft engine.

[0064] When the valve 11 is controlled in opening, the liquid expelled from the storage unit 9 is ejected towards the hydraulic motor 7 such that the latter transforms the hydraulic power of the liquid received into an exiting mechanical power.

[0065] The auxiliary system also comprises a tarpaulin 14 for liquid recovery connected to the hydraulic motor 7 by means of a drainage valve 15. This valve is tared such that the liquid is ejected from the circuit 10 as soon as the pressure exceeds a predetermined threshold.

[0066] The pyro-hydraulic storage unit 9 comprises, according to the embodiment of FIG. 1, an enclosure 20, a one-piece piston 16 housed in the enclosure and that defines two variable volume sealed compartments 17, 18. The compartment 17 houses a solid propellant cartridge 19 and the compartment 18 is a variable volume reserve of fluid. Hereinafter, it is considered that the liquid from the compartment 18 and from the hydraulic circuit is oil.

[0067] The storage unit 9 also comprises an ignition charge 25 adapted to initiate the combustion of the solid propellant cartridge 19 upon receiving a command from the control unit 12. Once ignited, the gas produced by the cartridge 19 disperses into the compartment 17 and applies a pressure on the piston 16 of the enclosure, which allows to pressurise the oil of the compartment 18 of the oil reserve. Oil is thus expelled towards the hydraulic motor 7 by means of the supply line 13 of the hydraulic circuit 10 and of the hydraulic circuit 10 as such.

[0068] A system according to the invention therefore allows for an occasional power input and can be used, either to reactivate a standby turboshaft engine, or to assist with an autorotation manoeuvre, or to ensure an additional instantaneous propulsion power, or to assist a helicopter which has lost the functioning of one of the engines thereof in the case of a two-engines or a three-engines helicopter, for example.

[0069] According to another embodiment, not represented in the figures, the pyro-hydraulic storage unit 9 comprises a plurality of solid propellant cartridges 19 housed in the compartment 17 of the enclosure 20.

[0070] In a variant or in a combination, and such as represented in FIG. 2, the storage unit can comprise a sealed membrane 23 arranged between the solid propellant cartridge 19 and the piston 16. The sealed membrane 23 aims to guarantee sealing between the two compartments of the enclosure. This membrane can be made from any type of sealed material.

[0071] In a complementary variant, the role of the piston can be held by a bladder which will ensure two major sought functions: movement of the volume and sealing between the two chambers.

[0072] According to another embodiment and such as represented in FIG. 3, the piston 16 is a differential section piston configured to be able to compress the liquid of the compartment for a liquid reserve at a pressure different from the pressure of the gas of the main compartment. This allows to adapt the torque delivered to the relay shaft.

[0073] The system described in relation to FIG. 1, is intended to be able to ensure the quick reactivation of a turboshaft engine. That being as such, the system according to the invention can be implemented to drive in rotation any shaft of a helicopter propulsion system, such as a shaft of a power transmission box of the helicopter, a shaft of an accessory box, a shaft of a gas generator of a turboshaft engine, or a shaft of a free turbine of a turboshaft engine. Generally, the system according to the invention can contribute to driving in rotation, on demand and when necessary, any type of shaft of a propulsion system. The person skilled in the art can easily apply the modifications necessary to the description above, in relation to a turboshaft engine to ensure the use of the system in the other applications covered by the invention.