Rotating blade aerodyne propulsion device with vertical take-off and landing, and aerodyne comprising at least one such propulsion device

Abstract

The invention relates to a propulsion device (1) for a rotating blade aerodyne with vertical take-off and landing, comprising a hollow chassis (4) and contra-rotating coaxial rotors (2, 3) with fixed-pitch blades (22, 32). The means for driving the rotation of each rotor (2, 3) comprise motor means and, for each rotor (2, 3), a rotating part capable of turning about a yaw axis (A1), located in the central opening of the respective rotor (2, 3) and connected to the latter via a ball joint with finger, the centre of which is the intersection of the prospective rotor disc and the yaw axis (A1) and for which the prohibited rotation is that about the axis of rotation of the rotor (2, 3). Means (6) for controlling the inclination of the rotors (2, 3) about the roll (A2) and pitch (A3) axes. Aerodyne equipped with the propulsion device (1).

Description

Propulsion device for rotary-wing aircraft with vertical takeoff and landing capabilities, and aircraft comprising at least one such propulsion device

[0001] The present invention relates to the technical field of rotary-wing aircraft with vertical takeoff and landing capabilities, and more specifically to the category of aircraft with contra-rotating coaxial rotor propulsion. In particular, the present invention relates to a contra-rotating coaxial rotor propulsion device and an aircraft comprising at least one such propulsion device.

[0002] The aerodyne according to the present invention can be manned (helicopter) or unmanned (drone).

[0003] In this application, the term "propulsion" includes the lifting of the aircraft, propulsion in flight in translation in the vertical, longitudinal and lateral directions, as well as attitude control in yaw, roll and pitch.

[0004] Patent FR2980117 B1 proposes a propulsion system for a contra-rotating coaxial rotor aircraft, comprising a single contra-rotating motor with two coaxial output shafts, each of which is fitted with a rotor consisting of a set of fixed-pitch blades. The opposite rotation of the rotors provides lift, and vertical translation and yaw attitude control are achieved by varying the rotational speed of the two rotors, both collectively and relative to each other. To steer the aircraft in longitudinal and lateral translation, simultaneously or not, the contra-rotating motor is proposed to be mounted on a slewing module carried by the frame, allowing it to pivot around the roll and pitch axes under the control of various means.Thus, the movement of the aerodyne in the horizontal plane is obtained by rotation around the roll axis and / or the pitch axis of the entire propulsion system, composed of the orientation module, the counter-rotating motor and the two rotors.

[0005] One of the advantages of this aircraft is its simpler structure, as it eliminates the collective and cyclic systems with swashplates and connecting rods that are conventionally used to vary the pitch of the blades, which are articulated at the hub of each rotor. The collective variation of the blade pitch controls vertical translational movement, while the asymmetric cyclic variation of the blade pitch controls the aircraft's attitude in roll and pitch, and therefore its movement in the horizontal plane. US patent 2256918 A describes an example of such a propulsion device with variable-incidence blades and complex collective and cyclic systems.

[0006] However, there is a risk of the aircraft being unresponsive to commands for movement in the horizontal plane. Indeed, since the entire propulsion system rotates around the horizontal roll and pitch axes located below the propulsion unit, the mass that must be set in motion is significant, resulting in increased inertia of the propulsion system and thus hindering its responsiveness.

[0007] Furthermore, in the case of an application to a drone, where the mass of the propulsion system will represent a significant portion of the aircraft's total mass, instability in flight is also a concern. Indeed, since the center of rotation of the propulsion system is located not at its center of gravity but in its lower part, at the level of the orientation module, the center of gravity will be constantly shifted due to the incessant roll and pitch movements during flight.

[0008] The maneuverability of the aerodyne according to patent FR2980117 B1 is therefore likely in practice to be insufficient, due to lack of responsiveness and in some cases also due to lack of stability.

[0009] The present invention aims to provide an aerodyne propulsion device with contra-rotating coaxial rotors offering improved maneuverability, while retaining the advantage of simplicity provided by the absence of collective and cyclic blade pitch variation systems.

[0010] The solution according to the present invention lies in mounting each rotor on a frame such that only the rotors are moved around the yaw, roll, and pitch axes, and not the entire propulsion system. This is made possible by using a hollow ball joint to connect each rotor to a rotating part located inside the frame, which is hollow for this purpose. This rotating part drives the rotor from within the frame, the ball joint allowing the rotor to rotate only around the roll and pitch axes, while the rest of the propulsion system remains fixed relative to these axes.

[0011] The present invention thus relates to a propulsion device for a rotary-wing aircraft with vertical takeoff and landing, using coaxial counter-rotating rotors movable in yaw, roll and pitch, the propulsion device comprising:

[0012] a hollow frame having a longitudinal axis which, in use, is coaxial with the yaw axis, an upper rotor and a lower rotor each having an annular central portion around the periphery of which fixed-pitch blades are fixed or intended to be fixed, the rotors being spaced one above the other along the yaw axis, each rotor defining a rotor disk and being capable of being driven in rotation about an axis of rotation which is perpendicular to the rotor disk and of being tilted about the roll axis and the pitch axis, drive means for driving each rotor in rotation about its axis of rotation, and tilt control means for tilting the rotors about the roll axis and the pitch axis,

[0013] the propulsion device being characterized by the fact that the drive means include motor means and, for each rotor, a rotating part which is capable of being driven in rotation around the yaw axis by the motor means, each rotating part being located in the central opening of the respective rotor and being connected to the latter by a finger ball joint, the center of which is the intersection of the respective rotor disk and the yaw axis and the axis of which is the axis of rotation of the rotor.

[0014] The expression "axis of the ball joint to finger" refers to the axis around which relative rotation between the rotor and the rotating part is prohibited.

[0015] According to a particular embodiment, the rotating parts are each formed by a drive ring mounted to rotate around a circular bearing of the chassis in which at least one window is provided through which extends a drive member suitable for being driven in rotation by the motor means and suitable for driving in rotation the drive ring.

[0016] According to a particular embodiment, each rotor is in spherical contact with the respective drive ring, the center of the contact sphere being the intersection of the yaw axis and the rotor disk of the rotor, and a groove opening into the inner surface of the central part of the rotor and whose length is parallel to the yaw axis is provided, in which a radial finger attached to the drive ring is engaged so as to transmit to the rotor the rotational movement of the drive ring around the yaw axis while allowing rotations of the rotor around the roll axis and the pitch axis.

[0017] According to a particular embodiment, each drive ring has on its inner surface a circumferential toothing and the respective drive member is a first toothed wheel in mesh with the toothing.

[0018] Non-contact training, for example using a magnetic training device, would also be possible.

[0019] According to a particular embodiment, the drive means comprise, for each rotor, a motor dedicated to said rotor and having an output shaft which is parallel to the yaw axis and whose rotational movement is transmitted to the drive element, optionally via a second toothed wheel mounted on the output shaft and meshed with the first toothed wheel.

[0020] According to a particular embodiment, the drive means for the two rotors are located inside the chassis, between the rotating parts, preferably the drive means comprising two dedicated motors aligned with each other, the output shaft of one motor being located on the upper rotor side while the output shaft of the other motor being located on the lower rotor side, the two motors extending along an inner wall of the lateral casing of the chassis.

[0021] With this configuration of the drive means between the two rotating parts, made possible by the use of a hollow frame, the propulsion system is significantly more compact than that of patent FR2980117 B1, since no additional height is added beyond that resulting from the distance between the rotors. The use of hollow drive rings, particularly those with the same diameter as the frame, further increases the compactness of the propulsion system, as some of the drive means, and potentially the tilt control means as discussed below, can be positioned at the same height as the rotors.

[0022] Furthermore, it is then possible to increase the size of the blades without necessarily increasing the size of the propulsion device, or at least by increasing it significantly less compared to patent FR2980117 B1.

[0023] This compact propulsion system is particularly advantageous in the case of a drone, and specifically for use requiring stealth, both visual and audible, and especially for military use.

[0024] Alternatively, the drive means may include at least one motor located outside the chassis and capable of producing an output movement, and means for transmitting the output movement from the motor(s) to the rotating parts to drive them into rotation, at least part of said transmission means being located inside the chassis.

[0025] Such a configuration, with the propulsion system partially located outside the chassis—made possible by the hollow chassis and the internal rotor drive—can generally be considered for a manned aircraft requiring greater engine power. Any known type of propulsion could be used, provided it produces counter-rotating motion for both rotors. This rotation can be transmitted to the rotating parts of the drive system via transmission mechanisms extending within the chassis, which are inherently within the capabilities of a skilled engineer, such as drive shafts, etc.

[0026] According to a particular embodiment, the tilt control means comprise at least two control rods of fixed length, located outside the frame, between the rotors, and movable in translation parallel to the yaw axis, in both directions, so that each is able to press by one end of it on one of the rotors and thus to rotate it around an axis, the control rods being spaced apart from each other angularly such that said axes are different, the tilt control means further comprising drive means for moving each of the rods in translation.

[0027] Such tilt control means contribute to the compactness of the propulsion system, since the control rods do not impose an increase in the distance between the rotors, which is the case for swashplate and connecting rod systems.

[0028] According to a particular embodiment, the drive means comprise, for each control rod, a dedicated bidirectional motor whose output shaft drives in rotation a screw parallel to the yaw axis and on which is mounted a nut locked in rotation, so that a rotation of the screw moves the nut along the screw, the nut carrying an arm which extends out of the chassis, passing through a slot parallel to the yaw axis, and to which the control rod is attached, the motors being, preferably, stepper motors.

[0029] According to a particular embodiment, for each control rod, a so-called mirror rod of fixed length is provided, located outside the chassis, between the rotors, which is parallel to and diametrically opposite to the respective control rod and movable in translation parallel to the yaw axis, in both directions, and each of whose two ends is in contact with a respective rotor.

[0030] According to a particular embodiment, the propulsion device comprises two control rods, at least the two ends of each of the control rods being in spherical contact with a sliding plate which is disposed on the central part of the face of each rotor oriented towards the other rotor, the sliding plate being mounted in such a way as to permit a relative rotation between the sliding plate and the rotor around the axis of rotation of the rotor, locking means being provided to prevent the rotation of the sliding plate relative to the rods.

[0031] The blocking means may include magnets, carried by the rods or by the sliding plate, magnets cooperating with a ferromagnetic material respectively carried or forming the sliding plate or the rods, such that a rotation of the sliding plate around the axis of rotation is prohibited by the force of attraction between the control rods and the sliding plate resulting from the cooperation of said magnets and said ferromagnetic parts.

[0032] According to another embodiment, the locking means comprise at least one connecting rod attached to the chassis by a first end at a pivot joint and attached to a sliding plate by a second end at a ball joint, the ends of the connecting rod being connected by a sliding rod, the connecting rod thus accompanying the movements of the sliding plate while preventing its rotation.

[0033] The sliding plate can be connected to the central part of the rotor by a bearing.

[0034] According to a particular embodiment, the propulsion device further comprises wear compensation rods, with return springs, located outside the frame, between the rotors, and movable in translation parallel to the yaw axis, in both directions, and each of whose two ends is in contact, by elastic stress, with the sliding plate, the control rods and the wear compensation rods, and where applicable the mirror rods, being regularly distributed around the frame and all at the same distance from the yaw axis.

[0035] According to a particular embodiment, all the motor means are located between the rotating parts, and preferably the motors dedicated to the tilt control are aligned with each other and arranged laterally to the motors dedicated to driving the rotating parts, the output shaft of one motor dedicated to the tilt control being located on the upper rotor side while the output shaft of the other motor is located on the lower rotor side, the screws extending next to the different motors and along the inner wall of the lateral casing of the chassis.

[0036] With such a configuration, particularly advantageous for an unmanned aircraft, the compactness of the propulsion system is maximized, with all the means for driving the rotation of the rotors and the means for controlling the tilt being contained within a space delimited in height by the two rotors.

[0037] Furthermore, only the individual rods are located outside the chassis, the other components being protected by it, making the propulsion system inherently watertight. This further increases the reliability of the propulsion system, which is already high due to the use of motor mechanisms, gears, and screw-nut systems, far more reliable than connecting rods.

[0038] The present invention also relates to a rotary-wing aircraft with vertical takeoff and landing, the propulsion of which is ensured by a propulsion device, characterized by the fact that the propulsion device is as defined above.

[0039] As mentioned above, the aerodyne can be manned (helicopter) or unmanned (drone).

[0040] To better illustrate the object of the present invention, a particular embodiment thereof will be described below, with reference to the accompanying drawings. These drawings show:

[0041] : overview of a propulsion device according to a particular embodiment of the present invention.

[0042] : perspective view of the propulsion device, the blades having been omitted.

[0043] : perspective view, in vertical section, of part of the upper rotor and the rotating ring.

[0044] : perspective view, in vertical section, of an upper part of the propulsion device, only the means of driving the rotation of the rotor being shown.

[0045] : perspective view, in vertical section, of the propulsion device, from a viewing angle showing the inside of the device, only the means of controlling the tilt of the rotors having been represented.

[0046] : view of the propulsion device in Figure 5, from another angle showing the outside of the device.

[0047] : schematic perspective view, from above, of the propulsion device, the chassis having been omitted.

[0048] : schematic perspective view, in vertical section, of the propulsion device, showing both the means of rotational drive and the means of tilt control.

[0049] : schematic top view of the propulsion system.

[0050] : view of a variant of the embodiment of the means for locking the sliding platforms.

[0051] : schematic side view of a drone according to the present invention.

[0052] : schematic side view of a helicopter according to the present invention, the drive means for rotating the rotors being located partly outside the chassis of the propulsion device.

[0053] Referring first to Figures 1 and 2, we can see that a propulsion device 1 according to the particular embodiment comprises two counter-rotating rotors 2, 3, namely an upper rotor 2 and a lower rotor 3, mounted on a hollow chassis 4 integrating all the components necessary for its autonomous operation, in particular means 5 for driving the rotation of the rotors 2, 3 and means 6 for controlling the tilt of the rotors 2, 3.

[0054] The chassis 4 is generally cylindrical in shape and has an upper end closed by a cap and a lower end by which the chassis 4 can be fixed to the cell of an aerodyne, an internal volume generally cylindrical being defined between said ends and the lateral envelope of the chassis 4.

[0055] As can be seen in Figures 4 and 8, supports 40 extend into the interior of the internal volume of the chassis 4, supports 40 to which are attached the components forming part of the drive means 5 and the tilt control means 6.

[0056] Each rotor 2, 3 comprises a central annular section 20, 30 which carries wings 21, 31 around its periphery for attaching blades 22, 32. Each blade 22, 32 is rigidly fixed to its respective wing 21, 31 with a fixed pitch. In other words, the blades 22, 32 are connected in a single unit to the central sections 20, 30.

[0057] In this embodiment, each rotor 2, 3 comprises two blades 22, 32 arranged at 180° to each other, and whose rotation describes a plane called the rotor disk. It is of course possible to provide each rotor with any number of blades, which together define a rotor disk.

[0058] The upper rotor 2 and the lower rotor 3 are mounted on the chassis 4 so that they can be driven in rotation around an axis of rotation perpendicular to their rotor disc, respectively at the upper end and the lower end of the chassis 4.

[0059] In particular, each rotor 2, 3 is connected to the chassis 4 via a drive ring 50 around which the rotor 2, 3 is mounted and to which it is connected by a finger ball joint 7, as can be better seen in Figures 3 and 4.

[0060] The chassis 4 has at each end a circular bearing 41 (figure 4) around which the drive ring 50 is mounted so as to be able to rotate around the longitudinal axis of the chassis 4, which in use is coaxial with the yaw axis A1, the rotational guidance being ensured by two bearings 51 spaced apart along the first axis.

[0061] The drive ring 50 has an outer face whose circumferential median region is formed by a convex surface 70 and an inner face provided, in its circumferential median region, with circumferential teeth 52. The drive ring 50 also has a radial finger 71 projecting from the convex surface 70.

[0062] The central annular part 20, 30 of the rotor 2, 3 has on its inner face a concave surface 23, 33 (Figure 8 for the lower rotor 3) into which opens a vertical groove 24 used to receive the finger 71.

[0063] The convex surface 70 and the concave surface 23, 33 are designed to be in spherical contact with each other, with the center of the contact sphere being the intersection of the first axis (or yaw axis A1, or longitudinal axis of the frame 4) and the rotor disc. Thus, the rotor 2, 3 can rotate about the second and third axes, which are perpendicular to each other and both perpendicular to the first axis. Furthermore, the groove 24 has the same width as the finger 71, so that once the finger 71 is engaged in the groove 24, relative rotation between the rotor 2, 3 and the drive ring 50 about the axis of rotation of the rotor 2, 3 is prevented. The height of the groove 24 is greater than the width of the finger 71, so that the latter does not impede the rotation of the rotor 2, 3 about the second and third axes.

[0064] The ball joint with finger 7 is therefore formed by the convex surface 70, the finger 71, the concave surface 23, 33 and the groove 24, and it is easily understood that it allows each rotor 2, 3 to be driven in rotation around its axis of rotation by means of the drive ring 50 and to be inclined relative to the drive ring 50.

[0065] Once fixed on the aerodyne, the first axis of the propulsion device 1 is coaxial with the yaw axis A1 of the aerodyne and each of the second and third axes is coaxial with one of the respective roll axis A2 and pitch axis A3.

[0066] We will now describe the means 5 for driving the rotation of rotors 2, 3 with reference to Figures 3 and 4.

[0067] In the embodiment shown, the drive means 5 comprise the two drive rings 50 and, for each of these, a drive motor 53 and a gear 54.

[0068] Each motor 53 includes an output shaft 55 whose rotational movement is transmitted to the drive ring 50 by the gear 54.

[0069] In the embodiment shown, the entire set of drive means 5 are located inside the chassis 4, more particularly between the two horizontal planes of the drive rings 50. Each motor 53 is a reduced electric motor and is carried by two supports 40, being oriented so that its output shaft 55 is parallel to the first axis and extends in the direction of the drive ring 50, which it must drive in rotation. The gear 54 includes a first gear 56 meshing with the teeth 52 of the drive ring 50 and meshing with a second gear 57 mounted on the output shaft 55. In order to allow meshing between the first gear 56 and the teeth 52, a through window 58 is provided in the circular bearing 41, through which the teeth of the first gear 56 and the teeth 52 pass.It will be easily understood that gear 54 is located at the same height as the teeth 51 which it drives in rotation.

[0070] Each motor 53 is dedicated to driving a respective rotor 2, 3 in order to ensure individual control of the rotation speed of the rotors 2, 3. They can therefore be made to rotate at the same speed, or at different speeds (but always in opposite directions) for the control of the attitude of the aerodyne in yaw.

[0071] We will now describe the means 6 for controlling the tilt of rotors 2, 3 with reference to Figures 5 and 6.

[0072] In the embodiment shown, the tilt control means 6 include, for each rotor 2, 3, a sliding plate 60, 61, a control rod 62 used to control the tilt of the rotor 2, 3 around the roll axis A2 and the pitch axis A3, a motor 63, a screw-nut system 64, a gear 65, a so-called mirror rod 66 and a plurality of wear compensation rods 67.

[0073] Each motor 63 is here a reduced, stepper motor, thus ensuring precise position control, located inside the chassis 4, between the two horizontal planes of the drive rings 50, and is carried by a support 40 fixed to the chassis 4 (Figure 8) being oriented so that its output shaft is parallel to the first axis and extends towards the respective end of the chassis 4.

[0074] Each screw-nut system 64 comprises a screw 64a parallel to the first axis and a nut 64b mounted on the screw 64a. The rotational movement of the output shaft of the motor 63 is transmitted to the screw 64a by a gear 65 comprising a third gear 65a mounted on the output shaft and meshing with a fourth gear 65b mounted at a corresponding end of the screw 64a.

[0075] Each nut 64b is attached to a control rod 62 which is located outside the frame 4, each control rod 62 being of fixed length and carried by an arm 64c extending from the respective nut 64b and passing through a slot provided for this purpose in the lateral casing of the frame 4, the slot being in longitudinal direction parallel to the first axis A1 and dimensioned to allow translation of the arm 64c over a sufficiently large stroke so that the rotors 2, 3 can be tilted up to desired maximum tilt angles.

[0076] Therefore, by controlling the motor 63 to rotate its output shaft in one direction or the other, the nut 64c and thus the control rod 62 can be raised or lowered, the distance traveled being a function of the angle of rotation of the output shaft.

[0077] Each control rod 62 has, at each of its two ends, a hemispherical surface 62a in contact with the free face of one of the sliding plates 60, 61. The control rods 62 are therefore located between the sliding plates 60, 61.

[0078] Each sliding plate 60, 61 is in the form of an annular piece having an upper face and a lower face. The upper sliding plate 60 is pivotally connected to the lower face of the central part 20 of the upper rotor 2, while the lower sliding plate 61 is pivotally connected to the upper face of the central part 30 of the lower rotor 3. More specifically, the face of the sliding plate 60, 61 that is in contact with the central part 20, 30 of the rotor 2, 3 has an annular tab 60a, 61a received in a groove of corresponding shape and dimensions provided in said central part 20, 30.Each sliding plate 60, 61 also carries a plurality of magnets, schematically represented in 61b and visible only for the sliding plate 61, each positioned to attract at least one of the rods 62, 66, 67, the latter being made, at least at their free ends, of ferromagnetic material for this purpose. Since the only degree of freedom of the rods 62, 66, 67 is translation in the direction parallel to the first axis, it is easily understood that the rotation of each of the sliding plates 60, 61 around the axis of rotation of the respective rotor 2, 3 is prevented, the tab 60a, 61a and the associated groove ensuring the rotational guidance of the rotor 2, 3 relative to the respective sliding plate 60, 61. The magnets 61b carried by each sliding plate 60 or 61 cooperating with the ferromagnetic material of the rods constitute blocking means to prevent the rotation of the sliding plate relative to the rotor 2 or 3.

[0079] Therefore, by moving a control rod 62 vertically up or down, the latter can press against the upper sliding plate 60 or against the lower sliding plate 61 respectively, thus rotating the latter, and therefore the rotor 2, 3 to which it is connected, around an axis of rotation which is horizontal, passes through the center of the finger ball joint 7 and is perpendicular to the straight line connecting said center and the point of contact between the control rod 62 and the sliding plate 60, 61. The sliding plate 60, 61 on which the control rod 62 does not press is also caused to tilt in the same way, but due to the attraction between the magnet 61b and the control rod 62.

[0080] The tilt angle will be a function of the distance traveled by the control rod 62 from a neutral position in which the two rotors 2 and 3 are horizontal, the distance being precisely controlled by the stepper motors 63.

[0081] The tilt of rotors 2 and 3 means a corresponding tilt of blades 22 and 32 around the roll axis A2 and / or the pitch axis A3, and therefore control of attitude in roll and pitch and of flight direction in the horizontal plane.

[0082] For each control rod 62, a mirror rod 66 of fixed length equal to that of the control rod 62 and diametrically opposite it is advantageously provided. Each mirror rod 66 is mounted for free translation in the direction parallel to the first axis A1, translational guidance being ensured by two lugs 42 (Figures 2 and 4) of the frame 4, external to the latter and spaced apart along the first axis A1. The mirror rods 66 serve to balance the forces applied to the rotors 2, 3 by the control rods 62.

[0083] The rods 67 are spring-loaded wear compensation rods and are angularly distributed around the frame 4, also supported by lugs 42 (Figure 2). These rods 67 ensure continuous contact at several points with the sliding plates 60, 61 in order to maintain the parallelism of the two rotors 2, 3 and the absence of backlash, even in the event of wear of the sliding plates 60, 61. Each rod 67 advantageously has a spherical contact surface at each of its ends.

[0084] In the embodiment shown, two control rods 62, two mirror rods 66 and four wear compensation rods 67 are provided, regularly distributed around the circumference of the chassis 4, and eight respective magnets 61b are provided for each sliding plate 60, 61, each in a position opposite a respective end of a respective rod 62, 66, 67.

[0085] As an alternative, it is possible to ensure the sliding of the plates 60 and 61 not by friction but by means of ball bearings arranged between the sliding plate 60, 61 and the central part 20, 30 of the rotor in question.

[0086] For a reduced mass aerodyne, magnetic locking means are sufficient to ensure the rotational locking of the sliding plates 60 and 61.

[0087] For a larger mass aerodyne, it will be desirable to provide means of mechanically locking the sliding platforms.

[0088] An example of such a blocking method is shown in Figure 10.

[0089] According to this embodiment, the locking means comprise at least one connecting rod B which is fixed to the chassis 4 at one end via a pivot joint B1 and fixed to a sliding plate 60 or 61 at the other end via a ball joint B2. The ends of the connecting rod are joined by a sliding rod B3. Thus, the connecting rod B can move with the sliding plate 60 or 61 to which it is attached while preventing the latter from rotating.

[0090] Control units (not shown), in particular to control the operation of the propulsion device 1, can be integrated inside the chassis 4, between the two rotors 2, 3. These control units can be motor control units, a GPS antenna, inertial measurement units, etc.

[0091] We can therefore see that the only mass put in motion for the control of attitude in roll and pitch is that of the two rotors 2, 3, which mass can be very small, so that the piloting of the aerodyne is very responsive.

[0092] Furthermore, the center of gravity remains stationary during roll and / or pitch movements, or is very little affected by them, thus preventing the creation of instability.

[0093] Propulsion device 1 therefore offers very high maneuverability of the aerodyne.

[0094] Furthermore, the propulsion system 1 is very compact, since all the means for driving the rotors' rotation and for controlling the rotors' tilt around the roll and pitch axes are located between the two rotors. Thus, as can be seen in Figure 11, which schematically represents a drone D whose body D1 is equipped with the propulsion system 1, the overall height of the drone D is not affected by the presence of the propulsion system 1. Therefore, the size of the blades can be increased without necessarily increasing the size of the rest of the aircraft, ensuring both visual and acoustic stealth.

[0095] It is understood that the particular embodiment just described has been given by way of example and not limitation, and that modifications may be made without departing from the present invention.

[0096] For example, as schematically illustrated in Figure 12, it may be envisaged that part of the propulsion means be located outside the chassis 4 and be carried by the airframe C of the aircraft, particularly as here in the case of a helicopter H which would require greater propulsion power. In such a case, for example, the second gears 57, mounted on the output shafts 55 of the motors 53 in the embodiment described above, could simply each be mounted on one end of a drive shaft Ab parallel to the yaw axis A1 and entering the chassis 4 through its open lower end, these drive shafts Ab, of which only one is shown, being connected by any suitable means to a dedicated motor M carried by the airframe C, such as for example via a gearbox Bt.

[0097] The propulsion device according to the present invention then makes it possible to benefit from the advantages of known contra-rotating coaxial rotor systems for helicopters, while overcoming their disadvantages due to the presence of cyclic control systems with swashplate and connecting rods, namely a high complexity and a penalizing vertical bulk, the helicopter not being able to be housed in a hangar not specifically designed to accommodate it.

Claims

1 - A propulsion device (1) for a vertical take-off and landing rotary-wing aerodyne, by means of coaxial contra-rotating rotors (2, 3) that can move in yaw, roll and pitch, the propulsion device (1) including:-    a hollow frame (4) having a longitudinal axis which, in use, is coaxial with the yaw axis (A1),-    an upper rotor (2) and a lower rotor (3) each having an annular central part (20, 30) to the periphery of which fixed pitch blades (22, 32) are secured or intended to be secured, the rotors (2, 3) being spaced apart one above the other along the yaw axis (A1), each rotor (2, 3) defining a rotor disc and being adapted to be driven in rotation about an axis of rotation that is perpendicular to the rotor disc and to be tilted about the roll axis (A2) and the pitch axis (A3),-    drive means (5) for driving each rotor (2, 3) in rotation about its axis of rotation, and-    tilt control means (6) for tilting the rotors (2, 3) about the roll axis (A2) and the pitch axis (A3),the propulsion device (1) being characterized in that the drive means (5) includes motor means (53) and, for each rotor (2, 3), a rotary part (50) which is adapted to be driven in rotation about the yaw axis (A1) by the motor means (53), each rotary part (50) being located in the central opening of the respective rotor (2, 3) and being connected to the latter by a pin spherical joint connection (7), the centre of which is the intersection of the respective rotor disc and the yaw axis (A1) and the axis of which is the axis of rotation of the rotor (2, 3). 2 - The propulsion device (1) according to claim 1, characterized in that the rotary parts (50) are each formed by a drive ring (50) rotatably mounted on a circular bearing surface (41) of the frame (4) in which is provided at least one window (58) through which extends a drive member (56) adapted to be driven in rotation by the motor means (53) and adapted to drive the drive ring (50) in rotation. 3 - The propulsion device (1) according to claim 2, characterized in that each rotor (2, 3) is in spherical contact with the respective drive ring (50), the centre of the contact sphere being the intersection of the yaw axis (A1) and the rotor disc of the rotor (2, 3), and there being provided a groove (24) which opens on the inner surface of the central part of the rotor (2, 3) and has a length parallel to the yaw axis (A1), in which groove (24) a radial pin (71) secured to the drive ring (50) is engaged so as to transmit to the rotor (2, 3) the rotational movement of the drive ring (50) about the yaw axis (A1) while allowing rotations of the rotor (2, 3) about the roll axis (A2) and the pitch axis (A3). 4 - The propulsion device (1) according to any one of claims 2 and 3, characterized in that each drive ring (50) is provided, on its inner surface, with a circumferential toothing (52) and the respective drive member (56) is a first gearwheel (56) in mesh with the toothing (52).5 - The propulsion device (1) according to claim 1, characterized in that the motor means (53) includes, for each rotor (2, 3), a motor (53) dedicated to said rotor (2, 3) and having an output shaft (55) parallel to the yaw axis (A1) and whose rotational movement is transmitted to the drive member (56).6 - The propulsion device (1) according to claim 1, characterized in that the motor means (53) for both rotors (2, 3) is located inside the frame (4), between the rotary parts (50), the motor means (53) including two dedicated motors (53) aligned with each other, the output shaft (55) of one motor (53) being located on the upper rotor (2) side while the output shaft (55) of the other motor (53) being located on the lower rotor (3) side, both motors (53) extending along an inner wall of the side envelope of the frame (4). 7 - The propulsion device (1) according to claim 1, characterized in that the motor means includes at least one motor located outside the frame (4) and adapted to produce an output motion, and means for transmitting the output motion of the motor(s) to the rotary parts (50) to drive them in rotation, at least part of said transmission means being located inside the frame (4).8 - The propulsion device (1) according to any one of claims 1 and 6, characterized in that the tilt control means (6) includes at least two control rods (62), of fixed length, located outside the frame (4), between the rotors (2, 3), and movable in translation parallel to the yaw axis (A1), in both directions, so that each is able to push with one end thereof against one of the rotors (2, 3) and thus to rotate it about an axis, the control rods (62) being angularly spaced from each other so that said axes are different, the tilt control means (6) further including motor means (63, 64, 65) for translating each of the rods (62). 9 - The propulsion device (1) according to claim 8, characterized in that the motor means (63, 64, 65) includes, for each control rod (62), a dedicated bidirectional motor (63) whose output shaft rotates a screw (64a) parallel to the yaw axis (A1) and on which is mounted a rotationally locked nut (64b), so that rotation of the screw (64a) moves the nut (64b) along the screw (64a), the nut (64b) carrying an arm (64c) which extends out of the frame (4), passing through a slot parallel to the yaw axis (A1), and to which the control rod (62) is secured. 10 - The propulsion device (1) according to claim 8, characterized in that for each control rod (62) there is provided a mirror rod (66) of fixed length, located outside the frame (4), between the rotors (2, 3), which is parallel to and diametrically opposite the respective control rod (62) and movable in translation parallel to the yaw axis (A1) in both directions, and each of the two ends of every mirror rod (66) is in contact with a respective rotor (2, 3). 11 - The propulsion device (1) according to claim 8, characterized in that it includes two control rods (62), at least the two ends of each of the control rods (62) being in spherical contact with a sliding plate (60, 61) which is provided on the central part (20, 30) of the side of each rotor (2,3) facing the other rotor (2, 3), the sliding plate being mounted in a manner allowing relative rotation between the sliding plate (60, 61) and the rotor (2, 3) about the axis of rotation of the rotor (2, 3), blocking means being provided to prevent rotation of the sliding plate relative to the rods. 12 - The propulsion device (1) according to claim 11, characterized in that the blocking means includes magnets, carried by the rods or by the sliding plate (60, 61), which magnets cooperate with a ferromagnetic material respectively carried by or forming the sliding plate or the rods, such that rotation of the sliding plate (60, 61) about the axis of rotation is prevented by the attractive force between the control rods (62) and the sliding plate (60, 61) resulting from the cooperation of said magnets and said ferromagnetic parts. 13 - The propulsion device (1) according to claim 11, characterized in that the blocking means includes at least one link (B) secured to the frame by a first end at a pivot connection (P1) and secured to a sliding plate (60, 61) by a second end at a spherical joint connection (B2), the ends of the link (B) being connected by a sliding rod (B3), the link (B) thus accompanying the movements of the sliding plate (60, 61) while preventing its rotation. 14 - The propulsion device (1) according to any one of claims 11 to 13, characterized in that the sliding plate is connected to the central part (20, 30) of the rotor (2, 3) by a rolling bearing. 15 - The propulsion device (1) according to claim 10, characterized in that it also includes spring-loaded wear take-up rods (67) located outside the frame (4), between the rotors (2, 3), and movable in translation parallel to the yaw axis (A1), in both directions, and each of two ends of every wear take-up rod (67) is in contact with the sliding plate (60, 61) by resilient bias, the control rods (62) and the wear take-up rods (67), and the mirror rods (66), being regularly distributed around the frame (4) and all at the same distance from the yaw axis (A1). 16 - The propulsion device (1) according to claim 9, characterized in that all the motor means (63, 64, 65) are located between the rotary parts (50), and the motors (63) dedicated to the tilt control are aligned with each other and arranged laterally to the motors (53) dedicated to driving the rotary parts (50), wherein the output shaft of one motor (63) dedicated to tilt control is located on the upper rotor side (2) and the output shaft of the other motor (63) is located on the lower rotor side (3), the screws (64a) extending next to the plurality of motors (53, 63) and along the inner wall of the side envelope of the frame (4). 17 - A vertical take-off and landing rotary-wing aerodyne (D, H), the propulsion of which is provided by a propulsion device (1), characterized in that the propulsion device (1) is as defined in claim 1. 

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