ROTARY WING AIRCRAFT PROVIDED WITH A TRANSMISSION SYSTEM COMPRISING AN EMERGENCY ELECTRIC MOTOR

Abstract

The present invention relates to an aircraft provided with a rotary airfoil, a power plant and an assistance system having an electric motor. The power plant comprises a power transmission box and at least one heat engine. The aircraft includes at least one accessory which is set in motion by a secondary output shaft of the power transmission box. The assistance system is provided with a mechanical connection module having a connection shaft which is connected to the secondary output shaft. A first connection member is connected to said at least one accessory and is connected by a first mechanical link internal to the connection shaft, a second connection member being connected to the electric motor and connected by a second mechanical link internal to the connection shaft.

Claims

1. An aircraft provided with a rotary airfoil and a power plant, said power plant comprising a power transmission box provided with a main output shaft rotating said rotary airfoil, said power plant comprising at least one heat engine connected by a mechanical input link to an input shaft of said power transmission box, said aircraft comprising at least one accessory which is set in motion by a secondary output shaft of the power transmission box, said aircraft comprising an assistance system provided with a mechanical connection module having a connection shaft which is connected to the secondary output shaft, said assistance system having a first connection member connected to said at least one accessory and connected by a first mechanical link internal to the connection shaft, said mechanical connection module having a second connection member connected to an electric motor and connected by a second mechanical link internal to the connection shaft, wherein said electric motor is an irreversible motor operating only in motor mode, said electric motor being requested to set said main output shaft in motion in the event of failure of at least one heat engine via the mechanical connection module.

2. The aircraft according to claim 1, wherein said at least one accessory is chosen from the group comprising hydraulic pumps, mechanical fans, electric generators and pneumatic compressors.

3. The aircraft according to claim 2, wherein said at least one accessory includes a first hydraulic pump, the first hydraulic pump belonging to a hydraulic circuit of said aircraft, the hydraulic circuit being connected to a plurality of servo controls for controlling a pitch of the blades of the rotary airfoil.

4. The aircraft according to claim 3, wherein said hydraulic circuit includes a second hydraulic pump which is set in motion by the power transmission box, said first mechanical link has a disconnection system which is configured to disconnect the first hydraulic pump from the connection shaft in the event of a failure of a heat engine.

5. The aircraft according to claim 1, wherein said second mechanical link includes a freewheel configured to transmit mechanical power only from the electric motor to the connecting shaft shaft.

6. The aircraft according to claim 1, wherein said assistance system includes a monitoring computer connected to the electric motor and to a sensor allowing detection of a failure of a heat engine, the monitoring computer being configured to request the operation of the electric motor if a said failure of a thermal engine is detected.

7. The aircraft according to claim 6, wherein said sensor includes a rotational speed sensor emitting a signal which varies as a function of the rotational speed of the connection shaft.

8. The aircraft according to claim 7, wherein the rotation speed sensor includes a tone wheel which is rotatably secured to the connection shaft and an inductive sensor arranged opposite the tone wheel.

9. The aircraft according to claim 1, characterized in that said assistance system includes motor equipment housing said electric motor.

10. The aircraft according to claim 9, wherein the mechanical connection module comprises a casing in which the connection shaft is at least partially located as well as the first mechanical link and the second connection member, said casing being fixed to the power transmission box, said at least one accessory being fixed to said casing, said motor equipment being fixed to said casing.

11. The aircraft according to claim 1, wherein said second mechanical link includes at least one speed reduction gear stage.

12. The aircraft according to claim 1, wherein said first mechanical link includes a coupling member allowing a misalignment.

13. The aircraft according to claim 1, wherein said first connection member includes connecting splines engaged on receiving splines of said at least one accessory.

14. The aircraft according to claim 1, wherein said second connection member includes connection splines engaged with drive splines of the electric motor.

15. The aircraft according to claim 1, wherein the assistance system includes at least one high-voltage DC electric battery which is electrically connected to the electric motor.

16. The aircraft according to claim 15, wherein said aircraft includes a low-voltage electrical network comprising at least one source of low-voltage electrical energy, said low-voltage electrical network having an electrical converter connected to said at least one high-voltage DC electric battery.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0086] The invention and its advantages will emerge in more detail in the context of the description which follows with examples given by way of illustration with reference to the appended figures, which show:

[0087] FIG. 1, a diagram illustrating an aircraft according to the invention,

[0088] FIG. 2, a partial internal view of the power transmission box of the aircraft of FIG. 1,

[0089] FIG. 3, an external view of the power transmission box of the aircraft of FIG. 1 equipped with an assistance system according to the invention,

[0090] FIG. 4, a three-dimensional view of a connection module according to the invention,

[0091] FIG. 5, a diagram illustrating the connection module according to the invention, and

[0092] FIG. 6, a view of a sensor allowing fault detection having a tone wheel and an inductive sensor.

[0093] Elements which are present in several distinct figures are assigned a single reference.

DETAILED DESCRIPTION OF THE INVENTION

[0094] FIG. 1 shows a diagram illustrating an aircraft 1 according to the invention. The aircraft 1 is provided with a rotary airfoil 3. The rotary airfoil 3 has a plurality of blades 4.

[0095] In order to set the blades 4 in rotation around an axis of rotation of the rotary airfoil 3, the aircraft 1 is provided with a power plant 5.

[0096] This power plant 5 comprises at least one heat engine 6. Optionally, this power plant 5 is a single-engine installation comprising a single heat engine 6. The heat engine(s) 6 are internal combustion engines. According to the illustrated example, the heat engine(s) 6 are turboshaft engines having a gas generator 8 and a working turbine 7, and in particular a free working turbine 7 according to this example. Alternatively, the heat engine(s) 6 are, for example, piston engines.

[0097] This heat engine 6 can be controlled and monitored in the usual way by an engine computer 9 and multiple usual sensors, not shown.

[0098] A computer may for example comprise at least one processor and at least one memory, at least one integrated circuit, at least one programmable system, at least one logic circuit, these examples not limiting the scope given to the expression “computer.” The term “processor” can denote a central processing unit known by the acronym CPU, a graphics processing unit GPU, a digital unit known by the acronym DSP, a microcontroller, etc.

[0099] Furthermore, the power plant 5 comprises a power transmission box 10 which is set in motion by the heat engine(s) 6. The power transmission box 10 is further connected to the rotary airfoil 3 in order to set this rotary airfoil 3 in rotation under the impulse of a heat engine 6 in a normal operating mode.

[0100] The power transmission box 10 may be of a conventional type. FIG. 2 illustrates an example of a power transmission box 10.

[0101] This transmission box 10 comprises an input shaft 11 which is mechanically linked to the heat engine 6 by a mechanical input link 25. The mechanical input link 25 can include a freewheel or the like, at least one shaft, at least one coupling means allowing a misalignment, etc. This input shaft 11 can set in motion rotating members of the power transmission box 10 so as to drive a main output shaft 19 in rotation, rotating the rotary airfoil 3. Such a main output shaft 19 can be connected to a rotor mast of the rotary airfoil 3 or be a part of this rotor mast.

[0102] For example, the input shaft 11 meshes with a wheel 12 sometimes referred to as a large wheel for convenience and because of its dimensions. This large wheel 12 is secured in rotation with an internal shaft 13 setting in motion at least one epicyclic speed reduction stage 14. For example, this epicyclic speed reduction stage 14 includes a planetary gear 15 which is secured to the internal shaft 13. In addition, this epicyclic speed reduction stage 14 comprises a plurality of differential-pinion gears 16 which roll both on the planetary gear 15 and on a fixed outer ring gear 18. The differential-pinion gears 16 are carried by a planet carrier 17 which meshes with the main output shaft 19, through a set of splines for example.

[0103] Furthermore, the power transmission box 10 may include at least one secondary output shaft 20, 21 for setting at least one accessory 33, such as a first hydraulic pump 33′, in motion. For example, at least one secondary output shaft 20, 21 is meshed with by the large wheel 12. At least one secondary output shaft 20, 21 may include a fuse section 22 and/or splines 23

[0104] According to another aspect and with reference again to FIG. 1, the pitch of the blades 4 of the rotary airfoil 3 can be controlled by flight controls. For example, the aircraft 1 comprises a usual set of swashplates 31 provided with a non-rotating plate and a rotating plate, the rotating plate being connected to each blade 4 or to each blade sleeve via a pitch connecting rod.

[0105] In addition, the aircraft 1 may include hydraulic servo controls 30 having at least one movable body and a fixed rod or a movable rod and at least one fixed body. Each servo control 30 is thus articulated to the non-rotating plate and to a non-rotating member of the aircraft 1. For example, each servo control 30 is provided with a control lever which is connected to the flight controls, a movement of the control lever making it possible for example to move a slide valve of the servo control.

[0106] To supply each body of the servo controls 30 hydraulically, the aircraft 1 comprises a hydraulic circuit 32. This hydraulic circuit 32 comprises at least a first hydraulic pump 33′ which is set in motion by a secondary output shaft 20 of the power transmission box 10. The first hydraulic pump 33′ is in fluid communication with at least one body of the servo controls 30.

[0107] Optionally, the hydraulic circuit 32 comprises at least one second hydraulic pump 36 which is set in motion by another secondary output shaft 21 of the power transmission box 10

[0108] According to another aspect and with reference to FIG. 3, the aircraft 1 comprises an assistance system 40 for assisting a pilot in a degraded operating mode in the event of failure of a heat engine 6.

[0109] This assistance system 40 is provided with an electric motor 75. Such an electric motor 75 is formed by an irreversible motor operating only in motor mode, and therefore cannot be used to generate electrical energy.

[0110] In addition, the assistance system 40 is provided with a mechanical connection module 41 which makes it possible to mechanically connect the electric motor 75 and the first hydraulic pump 33′ to the same secondary output shaft 20 of the power transmission box 10.

[0111] FIGS. 4 and 5 illustrate such a mechanical connection module 41.

[0112] In particular, FIG. 5 shows a diagram illustrating an embodiment of the mechanical connection module 41.

[0113] This mechanical connection module 41 has a connection shaft 42 which is mechanically connected to the secondary output shaft 20. For example, the connection shaft 42 is fitted with splines 43 that are engaged with splines 23 of the secondary output shaft 20. This connection shaft 42 can also be guided by at least two rolling members 69, 70.

[0114] In addition, the mechanical connection module 41 is provided with a first connection member 48 which is connected to the first hydraulic pump 33′. According to the illustrated example, the first connection member 48 comprises connecting splines 481 engaged on receiving splines 35 of a drive shaft 34 of the first hydraulic pump 33′.

[0115] The first connection member 48, and in this case the connecting splines 481 according to the illustrated example, is connected by a first mechanical link 45 internal to the connection shaft 42.

[0116] Such a first mechanical link 45 can be reduced to its simplest expression by showing a means for securing the first connection member 48 to the connection shaft 42, such as a welding means for example. If necessary, the connection shaft 42 can be machined to present the connection splines 481.

[0117] According to another example, the first mechanical link 45 may comprise at least one linking shaft and/or a disconnection system 83 and/or a coupling member 47 and/or splines 46 engaged on splines 44 of the connection shaft 42.

[0118] In particular, the first mechanical link 45 may include a coupling member 47 allowing a misalignment between two mechanical members. According to one example, such a coupling member 47 may comprise a first flange secured to the connection shaft 42, directly or indirectly via splines 46 engaged on splines 44 of the connection shaft 42, and a second flange linked by a flexible member to the first flange. The flexible member can allow an axial and/or radial misalignment between the flanges.

[0119] The second flange can be connected directly or indirectly to the first connection member 48

[0120] In a complementary or alternative manner, a disconnection system 83 can be configured to disconnect the first hydraulic pump 33′ from the connection shaft 42 in the event of a breakdown of a heat engine 6. Such a disconnection system 83 may in particular be requested when the hydraulic circuit 32 comprises a second hydraulic pump 36 which is set in motion by the power transmission box 10. Such a disconnection system 83 may for example comprise a clutch.

[0121] According to the illustrated example, the first mechanical link 45 thus successively comprises splines 46 engaged on splines 44 of the connection shaft, a linking shaft connecting the splines 46 to a coupling member 47, a disconnection system 83, then the first connection member 48.

[0122] According to another aspect, the mechanical connection module 41 comprises a second connection member 49 which is connected to the electric motor 75. According to the illustrated example, the second connection member 49 comprises connection splines 491 engaged on drive splines 77 of an output motor shaft 76 of the electric motor 75.

[0123] The second connection member 49, and in this case the connection splines 491 according to the illustrated example, is connected by a second mechanical link 50 internal to the connection shaft 42. The second connection member 49 can be movable in rotation about a second axis AX2 parallel to a first axis AX1 about which the first connection member 48 is movable in rotation. Optionally, the connection shaft is also movable in rotation about the first axis of rotation AX1.

[0124] The second mechanical link 50 can be reduced to its simplest expression or can optionally comprise at least one speed reduction gear stage 51, 61. By way of illustration, the electric motor 75 can be sized to drive its output motor shaft 76 in rotation at approximately 20,000 revolutions per minute while the connection shaft 42 is configured to perform a rotation at approximately 6,000 revolutions per minute.

[0125] According to the illustrated example, the second mechanical link 50 comprises a first speed reduction gear stage 61 setting in motion a second speed reduction gear stage 51 which is connected to the connection shaft 42.

[0126] For example, the second mechanical link 50 comprises a first internal shaft 64 which is integral with the second connection member 49. For example, the second connection member 49 includes splines of the first internal shaft 64. This first internal shaft 64 can be guided in rotation by at least two rolling members 67, 68. In addition, the first internal shaft 64 carries a first pinion 62 of the first stage 61.

[0127] The second mechanical link 50 may include a second internal shaft 59. This second internal shaft 59 can be guided in rotation by at least two rolling members 65, 66. In addition, the second internal shaft 59 carries a first wheel 63 of the first stage 61. The first wheel 63 is meshed with by the first pinion 62 and may include a number of teeth greater than the number of teeth of the first pinion 62. For example, the first pinion 62 has 18 teeth and the first wheel 63 has 37 teeth.

[0128] In addition, the second internal shaft 59 carries a second pinion 52 of the second stage 51. The second pinion 52 meshes with a second wheel 53 of the second stage 51, this second wheel 53 being connected to the connection shaft 42 directly or indirectly. The second wheel 53 may include a number of teeth greater than the number of teeth of the second pinion 52. For example, the second pinion 52 has 19 teeth and the second wheel 53 has 42 teeth.

[0129] According to one aspect, the second mechanical link 50 may include a freewheel 55. This freewheel 55 has the function of transmitting mechanical power only from the electric motor 75 to the connection shaft 42.

[0130] Usually, the freewheel 55 comprises a driving part 56, a driven part 57 and at least one connection member 58 interposed between the driving part 56 and the driven part 57 so as to connect them in rotation when the driving part 56 tends to perform a rotation at a speed greater than or equal to the driven part 57. For example, a connection member 58 can take the form of a ball, a roller, a pawl, etc.

[0131] According to the illustrated example, the driving part 56 can be secured to the second wheel 53 by usual means, such as screwing means, welding, splines, etc. Therefore, the driven part 57 can be secured to the connection shaft 42 by usual means, such as screwing means, welding, splines, etc.

[0132] According to another aspect, the electric motor 75 can be housed at least partially within an enclosure of a sub-assembly called “motor equipment 101” for convenience. For example, the output motor shaft 76 of the electric motor 75 comes out of this enclosure to enter the second connection member 49. The enclosure can include one or more parts that are fixed to one another.

[0133] Likewise, a casing 102 can be included in the mechanical connection module 41. Such a casing 102 thus makes it possible to at least partially accommodate the connection shaft 42 as well as the first mechanical link 45 and the second connection member 49. This casing 102 may include one or more parts fixed to one another.

[0134] According to the illustrated example, the casing 102 has an opening through which the secondary output shaft 20 passes, an opening through which the output motor shaft 76 passes and an opening through which the drive shaft 34 of the first hydraulic pump 33′ passes.

[0135] In addition, the casing 102 can be fixed to the power transmission box 10, for example by screwing means. Likewise, an enclosure 103 of the first hydraulic pump 33′ and an enclosure of the motor equipment 101 are each optionally fixed to the casing 102, for example by screwing means.

[0136] Furthermore, the assistance system 40 can comprise a sensor 80 so as to detect an engine failure of the heat engine 6. Optionally, this sensor 80 includes a rotational speed sensor emitting a signal which varies as a function of the rotational speed of the connection shaft 42.

[0137] According to FIG. 6, the rotation speed sensor comprises a tone wheel 81 secured in the usual manner in rotation to the connection shaft 42. The tone wheel 82 comprises a wafer having a succession of holes and “teeth.”

[0138] In addition, the speed sensor includes an inductive sensor 82 directed towards the tone wheel 81. This inductive sensor 82 can be carried by the casing 102. An inductive sensor 82 may include a coil mounted on a metal rod and a permanent magnet. The inductive sensor 82 is mounted opposite the tone wheel 81. The magnetic flux which occurs between the teeth or the holes of the tone wheel 81 allows the inductive sensor 82 to generate a sinusoidal electrical voltage which varies according to the speed of rotation of the connection shaft 42 and the distance separating the inductive sensor 82 from the tone wheel 81. According to one example, the tone wheel 81 has 94 holes and the sensor 82 is a sensor from the company Honeywell® known under the trade name MA3055.

[0139] According to another aspect and with reference again to FIG. 1, the assistance system 40 has a monitoring computer 85 which is connected to the electric motor 75. The monitoring computer 85 may be part of the motor equipment 101.

[0140] The monitoring computer 85 can be connected by wired or non-wired links, where appropriate, to the sensor 80, to the motor computer 9 or even to the disconnection system 83 or to at least one man/machine interface.

[0141] In one aspect, the assistance system 40 may include at least one high-voltage DC electric battery 86 which is electrically connected to the electric motor 75.

[0142] The expression “high electrical voltage” refers to an electrical voltage greater than 50 volts, and for example 300 or 500 volts.

[0143] According to the example of FIG. 1, the high-voltage DC electric battery 86 is connected to the monitoring computer 85, this monitoring computer 85 electrically supplying the electric motor 75 if necessary.

[0144] According to one possibility, the aircraft 1 can also include a low-voltage electrical network 90. The expression “low electrical voltage” refers to an electrical voltage lower than 50 volts, and for example 28 volts. This low-voltage electrical network 90 can be provided with at least one source of low-voltage electrical energy 91. For example, said at least one source of low-voltage electrical energy 91 may comprise a ground connection 92 and/or an electric machine 93 possibly serving as an electric generator and starter for the heat engine 6 and/or a low-voltage electric battery 94. Each source of low-voltage electrical energy 91 can be electrically connected to an electrical distribution network 95. In addition, a low-voltage DC to high-voltage DV electrical converter 96 can be electrically connected to the electrical distribution network 95 and to each high-voltage DC electric battery 86.

[0145] Under these conditions, the electric motor 75 is inoperative during normal operating mode, except in the case of a test. When the monitoring computer 85 receives a signal from the sensor 80 or from the engine computer 9 signaling a failure of a heat engine, the monitoring computer 85 is configured to request the operation of the electric motor 75. For example, the sensor 80 continuously emits a signal carrying a current rotation speed of the connection shaft 42. Consequently, as soon as this current rotation speed is below a threshold or alternatively when a deceleration exceeds a threshold value, the monitoring computer 85 activates the electric motor 75.

[0146] The electric motor 75 is then activated to set the power transmission box 10 in motion and to participate in the rotation of the rotary airfoil 3.

[0147] Optionally, the monitoring computer 85 also disconnects the first hydraulic pump 33′ depending on the variant.

[0148] The monitoring computer 85 can also activate the electric motor 75 by applying other logics, for example based on the teaching of the document U.S. Pat. No. 9,045,223.

[0149] The electric motor 75 can also be in a so-called “armed” configuration in which it is rotated prior to detecting a failure of a heat engine, but at a lower rotational speed than that allowing it to drive the connection shaft 42 in rotation.

[0150] Consequently, as soon as the monitoring computer 85 receives a signal from the sensor 80 or from the engine computer 9 signaling a failure of a heat engine, the rotation speed of the output motor shaft 76 of the electric motor 75 can be increased instantly to rotate the connection shaft 42 and to prevent its rotation speed from decreasing.

[0151] Of course, the present invention is subject to many variations in its implementation. Although several embodiments have been described, it will be understood that it is not conceivable to exhaustively identify all of the possible modes. It is of course conceivable to replace a described means by an equivalent means without departing from the scope of the present invention.