HYDRAULIC DEVICE FOR EMERGENCY STARTING A TURBINE ENGINE, PROPULSION SYSTEM OF A MULTI-ENGINE HELICOPTER PROVIDED WITH ONE SUCH DEVICE, AND CORRESPONDING HELICOPTER

Abstract

Emergency start-up device for a turboshaft engine of a helicopter, comprising: a hydraulic motor which is mechanically connected to said turboshaft engine; a hydropneumatic store which is connected to said hydraulic motor by a hydraulic circuit for supplying pressurised liquid to said hydraulic motor; and a hydraulic valve which has controlled quick opening, arranged on the hydraulic circuit between said store and said hydraulic motor, and is suitable for being placed on command at least in an open position in which the liquid can supply said hydraulic motor, or in a closed position in which said hydraulic motor is no longer supplied with pressurised liquid.

Claims

1. Emergency start-up device for a turboshaft engine of a helicopter, comprising: a hydraulic motor suitable for being mechanically connected to said turboshaft engine and is suitable for setting into rotation said engine to facilitate the start-up thereof; a hydropneumatic store connected to said hydraulic motor by a hydraulic circuit for supplying pressurised liquid to said hydraulic motor; a hydraulic valve having controlled opening, the hydraulic valve being arranged on the hydraulic circuit between said store and said hydraulic motor, and is suitable for being placed on command at least in an open position in which the liquid can supply said hydraulic motor for facilitating a start-up of said turboshaft engine when the device is used with said turboshaft engine, or in a closed position in which said hydraulic motor is no longer supplied with pressurised liquid; and a reservoir for recovering liquid, the reservoir being connected to said hydraulic motor by a purge valve.

2. Device according to claim 1, wherein said hydropneumatic store is selected from the group comprising a bladder-type store, a membrane-type store and a piston-type store.

3. Device according to claim 1, wherein said hydraulic motor comprises a propshaft suitable for being mechanically connected to a gearbox shaft of an accessory gearbox of said turboshaft engine by meshing means comprising at least one free wheel supported by said propshaft.

4. Device according to claim 3, wherein said meshing means further comprise: a first meshing stage comprising said propshaft supporting a main pinion mounted on said free wheel and a pumping pinion; a second meshing stage comprising said gearbox shaft supporting a main pinion meshed with said main pinion from said first meshing stage, and a pumping pinion; and an intermediate meshing stage comprising an intermediate shaft supporting a connection pinion movable between an engaged position in which it is engaged together with said pumping pinions from the first and second stages, and a disengaged position in which it does not interfere with said pumping pinions from the first and second stages.

5. Propulsion system for a multi-engine helicopter comprising turboshaft engines which are suitable for being connected to a power transmission gearbox, comprising: at least one hybrid turboshaft engine among said turboshaft engines, said at least one hybrid turboshaft engine being capable of operating in at least one standby regime during a stabilised flight of the helicopter, the other turboshaft engines operating only during this stabilised flight; and at least one device for the emergency restart of a hybrid turboshaft engine according to claim 1, said at least one device suitable for being able to transfer said hybrid turboshaft engine out of said standby regime and reach a rated regime in which it supplies mechanical power to said power transmission gearbox.

6. System according to claim 5, wherein said at least one hybrid turboshaft engine includes two turboshaft engines and wherein two emergency restart devices are provided, each turboshaft engine of said two hybrid turboshaft engines being associated with a restart device.

7. System according to claim 5, wherein said at least one hybrid turboshaft engine includes two turboshaft engines and wherein a single restart device including two hydraulic motors is provided, each hydraulic motor connected to one of the hybrid turboshaft engines of said two hybrid turboshaft engines, respectively, said hydraulic valve being a three-way valve controlled to orient the fluid towards said hydraulic motor of the hybrid turboshaft engine to be restarted.

8. Helicopter comprising a propulsion system according to claim 5.

9. (canceled)

Description

LIST OF THE DRAWINGS

[0057] Other aims, features and advantages of the invention will become apparent upon reading the following description which is provided purely on a non-limiting basis and relates to the accompanying drawings, in which:

[0058] FIG. 1 is a schematic view of a device for the start-up of a turboshaft engine according to one embodiment of the invention,

[0059] FIG. 2 is a schematic view of an architecture of a propulsion system of a helicopter according to one embodiment of the invention,

[0060] FIG. 3 is a schematic view of an architecture of a propulsion system of a helicopter according to another embodiment of the invention,

[0061] FIG. 4 is a schematic view of meshing means of a start-up device according to one embodiment of the invention in a position in which the device operates in the motor mode,

[0062] FIG. 5 is a schematic view of meshing means of a start-up device according to one embodiment of the invention in a position in which the device operates in the pump mode.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

[0063] In the drawings, the scales and the proportions are not respected for the sake of illustration and clarity.

[0064] FIG. 1 is a schematic view of a device for the start-up of a turboshaft engine 6 according to one embodiment of the invention.

[0065] Such a device comprises a hydraulic motor 7 which is mechanically connected to the turboshaft engine 6 by means of a free wheel 8. This hydraulic motor 7 can be a motor having axial or radial pistons. The function thereof is to transform the hydraulic power that it receives into mechanical power, thus making it possible to bring about the start-up of the turboshaft engine.

[0066] This hydraulic motor 7 is preferably mounted on the turboshaft engine 6 by means of an accessory gearbox, which is not shown in FIG. 1.

[0067] The device further comprises a hydropneumatic store 9 which is connected to the hydraulic motor 7 by means of a hydraulic circuit 10 for supplying pressurised liquid to this hydraulic motor 7. This hydropneumatic store 9 is, according to the embodiment in FIG. 1, a monobloc piston-type store 16. The piston 16 defines a compartment 17 for gas having a variable volume and a compartment 18 for oil having a variable volume. The gas compartment 17 is for example filled with nitrogen, helium or argon. This gas from the gas compartment 17 exerts a pressure on the piston 16 which can be moved towards an increase in the volume of the gas compartment 17 and a reduction in the volume of the oil compartment 18. The oil is thus pushed towards the hydraulic circuit 10.

[0068] The supply of the hydraulic motor 7 is dependent on a hydraulic valve 11 which has controlled quick opening and is arranged on the hydraulic circuit 10 between the store 9 and the hydraulic motor 7.

[0069] This hydraulic valve 11 is controlled by a control device 12, which is preferably the control computer of the turboshaft engine 6, which further makes it possible to define the operating regime of the turboshaft engine.

[0070] When the valve 11 is controlled in opening, the oil from the oil compartment 18 of the store 9 is ejected towards the hydraulic motor 7 so that said motor transforms the hydraulic power of the oil which is received into mechanical power at the output.

[0071] The start-up device also comprises a reservoir 14 for recovering liquid which is connected to the hydraulic motor 7 by means of a purge valve 15. This valve is set in such a way that the oil is ejected from the circuit 10 once the pressure exceeds a predetermined threshold.

[0072] The start-up device from FIG. 1 is advantageously provided in an architecture of a propulsion system of a twin-engine helicopter as shown in FIG. 2.

[0073] According to the embodiment in FIG. 2, the propulsion system comprises two turboshaft engines 6, 16 which are connected to a power transmission gearbox 22, which in turn drives a rotor of the helicopter (not shown in the drawings). Each turboshaft engine is a hybrid turboshaft engine, which can be placed in at least one standby regime during a stabilised flight of the helicopter, from which it can exit again in an emergency by means of a start-up device according to the invention. A turboshaft engine comprises, in a known manner, a gas generator, a combustion chamber and a free turbine.

[0074] The standby regime is for example one of the following operating regimes: [0075] a standby regime, referred to as a conventional idling regime, in which the combustion chamber is ignited, and the shaft of the gas generator rotates at a speed of between 60 and 80% of the rated speed, [0076] a standby regime, referred to as a conventional super-idling regime, in which the combustion chamber is ignited, and the shaft of the gas generator rotates at a speed of between 20 and 60% of the rated speed, [0077] a standby regime, referred to as an assisted super idling regime, in which the combustion chamber is ignited, and the shaft of the gas generator rotates, with mechanical assistance, at a speed of between 20 and 60% of the rated speed, [0078] a standby regime, referred to as a banking regime, in which the combustion chamber is extinguished, and the shaft of the gas generator rotates, with mechanical assistance, at a speed of between 5 and 20% of the rated speed, [0079] a standby regime, referred to as a shutdown regime, in which the combustion chamber is extinguished, and the shaft of the gas generator is at a complete stop.

[0080] The start-up device comprises, in addition to the elements described in connection with FIG. 1, a hydraulic motor 17 which is connected to the turboshaft engine 16 by means of a free wheel 18. Furthermore, the hydraulic circuit 10 extends from the hydropneumatic store 9 as far as the hydraulic motor 17 and the hydraulic motor 7.

[0081] The controlled valve 11 is, according to this embodiment, a three-way valve which is suitable for allowing, on command, either the supply of the hydraulic motor 17 which is connected to the turboshaft engine 16, or the supply of the hydraulic motor 7 of the turboshaft engine 6. The command is dependent on the turboshaft engine in standby which has to exit the standby regime thereof in an emergency.

[0082] The operating principle of the start-up device of this architecture is, for each turboshaft engine 6, 16, identical to that described in connection with FIG. 1.

[0083] FIG. 3 is a propulsion system according to another embodiment of the invention. According to this embodiment, a separate start-up device is provided for each turboshaft engine. In other words, a hydropneumatic store 29, 39 is associated with each hydraulic motor 7, 17, and a valve 21, 31 is associated with each store 29, 39 to ensure the supply of the motors and the restart of the corresponding turboshaft engine. The valves 21, 31 are controlled by the control unit 12. Only the reservoir 14 for recovering oil is common to the two start-up devices. According to another variant which is not shown in the drawings, all the elements are separate, including the recovery reservoir 14.

[0084] The propulsion system further comprises, for each engine 6, 16, a separate purge valve 15, 15 which is associated with this engine. Each purge valve 15, 15 has a dual function.

[0085] Firstly, when the associated engine is inactive, it makes it possible to keep the oil inside said engine. The purge valve thus makes it possible to avoid the engine starting empty.

[0086] Secondly, when one of the two engines starts, the oil from the return line of the engine in operation must be prevented from supplying the other engine (which would otherwise also start rotating). The purge valve thus makes it possible in this situation to act as a non-return device for isolating the other engine.

[0087] Furthermore, according to the embodiment from FIG. 3, the hydropneumatic stores 29, 39 are bladder-type stores. Each store 29, 39 comprises a bladder 28, 38 containing a gas, of the nitrogen, argon or helium type, which is arranged within the enclosure of the store which is filled with oil. Such a bladder plays the role of the gas compartment 17 of the store 9 from FIG. 1. In another embodiment, the hydropneumatic stores are membrane-type or piston-type stores.

[0088] FIGS. 4 and 5 are schematic views of one embodiment of the mechanical connection between the hydraulic motor 7 and an accessory gearbox 13 of the turboshaft engine 6.

[0089] This mechanical connection is formed by meshing means which comprise a first meshing stage formed by a propshaft 40, which is the output shaft of the hydraulic motor 7, a main pinion 41 which is supported by the propshaft 40 and mounted on the free wheel 8, and a pumping pinion 42.

[0090] The meshing means further comprise a second meshing stage formed by a gearbox shaft 60, a main pinion 61 which is supported by the gearbox shaft 60 and meshed with the main pinion 41 from the first meshing stage, and a pumping pinion 62 which is supported by the gearbox shaft 60.

[0091] The meshing means lastly comprise an intermediate meshing stage which is formed by an intermediate shaft 50 supporting a connection pinion 52.

[0092] The connection pinion 52 is configured to have two positions, an engaged position which is shown by FIG. 5, and a disengaged position which is shown by FIG. 4.

[0093] In the engaged position in FIG. 5, the pinion is set into rotation by the pumping pinion 62 which is supported by the shaft 60 of the accessory gearbox 13, and said pinion sets into rotation the pumping pinion 42 which is supported by the propshaft 40. Thus, in this position, the shaft 40 is set into rotation by the shaft 60 of the accessory gearbox. The hydraulic motor 7 thus operates in the hydraulic pump mode, and this makes it possible to re-inject the oil towards the hydropneumatic store. The free wheel 8 permits the free rotation of the pinion 41.

[0094] In the disengaged position in FIG. 4, the pinion 52 is not mechanically connected to the pumping pinions 42, 62. Also, in this position, the main pinion 41 which is supported by the propshaft 40 drives the pinion 61 which is supported by the shaft 60 of the accessory gearbox. This position is the position which allows the quick start-up of the turboshaft engine.

[0095] The displacement of the pinion 52 from the disengaged position into the engaged position can be ensured by a hydraulic, pneumatic or electric actuator, or by any equivalent means.

[0096] The principle of using a device for the start-up of a turboshaft engine within a twin-engine architecture as shown in FIG. 2 is as follows: [0097] when the flight conditions are favourable, an order is emitted to place a turboshaft engine in standby to save fuel (standby regime selected from the standby regimes mentioned above). [0098] the computers of the turboshaft engines then determine which turboshaft engine can be placed in standby and order the placement in standby thereof (in the following, the turboshaft engine 6 is considered to be placed in standby, and only the turboshaft engine 16 supplies power to the power transmission gearbox 22), [0099] the turboshaft engine 6 is in the standby regime (this standby regime can be one of the above-mentioned standby regimes, with an ignited or extinguished chamber, with or without mechanical assistance), [0100] during the flight, the turboshaft engine 16 suddenly fails, or the pilot decides to carry out an emergency restart of the turboshaft engine 6 for a specific emergency manoeuvre, [0101] the combustion chamber of the turboshaft engine 6 is then quickly reignited (in the case of a standby regime with an extinguished chamber), [0102] after a predetermined period of time, the control unit 12 orders the opening of the latching valve 11 towards the turboshaft engine 6, [0103] the hydraulic motor 7 then passes quickly (in a period of time of less than a second) from 0 rpm to the docking speed of the gas generator initially in the standby regime whilst transforming the hydraulic power into mechanical power, making it possible to drive the gas generator of the turboshaft engine 6 by means of the free wheel 8, [0104] the hydraulic motor 7 follows the drive of the turboshaft engine 6 for a short period of time, for example of less than 10 seconds, during which time the turboshaft engine has reached the emergency regime thereof, [0105] the emergency start-up of the turboshaft engine 6 is thus obtained.

[0106] The docking speed corresponds to the standby speed of the gas generator divided by the ratio of reduction in speeds between the shaft of the gas generator and the input of the accessory gearbox of the turboshaft engine on which the hydraulic starter is mounted.

[0107] A device according to the invention thus makes it possible to quickly restart a turboshaft engine in standby which has recourse only to members which are inexpensive, are simple to use and install, can be tested on rigs and make it possible to reload the hydropneumatic store.

[0108] The invention is not limited to only the described embodiments. In particular, the propulsion system can comprise three turboshaft engines for equipping a three-engine helicopter, and a person skilled in the art can easily determine, based on the teachings of the present text, how to adapt the described embodiments to a multi-engine, in particular three-engine, propulsion system.