WO2025032421A1

WO2025032421A1 - Personal aerial vehicle or drone with improved propeller units

Info

Publication number: WO2025032421A1
Application number: PCT/IB2024/057368
Authority: WO
Inventors: Pietro Perlo; Davide PENSERINI
Original assignee: Interactive Fully Electrical Vehicles S.R.L.
Priority date: 2023-08-09
Filing date: 2024-07-30
Publication date: 2025-02-13

Abstract

A personal aerial vehicle, or drone, comprises front wings (W) and rear wings (R) in which there are integrated annular propeller units (P), having substantially vertical axes of rotation, for the sustainment of the aerial vehicle. A tail propeller unit (PX), having an axis of rotation substantially parallel to the longitudinal direction of the aerial vehicle, enables the aerial vehicle to be propelled forward in flight. The aerial vehicle also has an upper wing (WX) in the shape of a disc, being arranged above a central body (B). Each annular propeller unit has a rotor ring (RO) rotatably supported by a stator ring (S) by means of an air-supporting system, including two annular chambers (8) facing two opposite faces of the rotor ring (RO), which receive pressurized air from an electrically driven pump (12). The annular propeller units have blades (L) carried by the rotor ring (RO) and extending radially towards the inside of the rotor ring (RO). In an example, the blades (L) have a triangular shape, and have faces with concentric circumferential ribs (N) to guide the relative airflow over the blades. As an alternative to the annular propeller units, e.g. for the tail propeller unit, it is possible to use propeller units having blades (L) extending from a central hub (H), arranged in a plurality of overlapping and spaced apart layers. Connecting elements (18) join the ends of blades (L) which belong to different layers and which are arranged in corresponding, equal or mutually offset, angular positions, so as to improve the efficiency and the silent operation of the propeller unit. The aerial vehicle may have a modular structure, with a base module (M1) which integrates the wings and has a cargo hold, ad additional modules which define the cabin (M2) and the discoidal upper wing (WX).

Description

PERSONAL AERIAL VEHICLE OR DRONE WITH IMPROVED PROPELLER UNITS

TEXT OF THE DESCRIPTION

5 Field of the Invention

The present invention concerns a personal aerial vehicle or a drone and a propeller unit to be used with such aerial vehicle.

Specifically, the invention relates to personal aerial vehicles or to drones of the type comprising:

- a supporting structure, defining a central body with front wings and rear wings,

- a plurality of annular propeller units, having substantially vertical axes of rotation, with reference to the ground-supported condition of the aerial vehicle, and located in the front wings and in the rear wings of the5 aerial vehicle, for in-flight sustainment of the aerial vehicle, and

- at least one propeller unit carried by a tail of the central body, having an axis of rotation substantially parallel to the longitudinal direction of the aerial vehicle, to propel the aerial vehicle forward in flight, and

- an additional upper wing in the form of a disc, arranged above the0 central body, wherein each annular propeller unit comprises:

- a stator ring rigidly connected to an aerial vehicle supporting structure,

- a rotor ring rotatably mounted coaxially within the stator ring, having5 a radially internal surface that is substantially cylindrical,

- one or more blades extending radially from said inner surface of the rotor ring, towards the axis of the rotor ring,

- at least one power unit carried by an aerial vehicle supporting structure and having an output shaft spaced from the axis of the rotor ring and connected to the rotor ring by a belt drive,

- wherein the rotor ring is rotatably supported by the stator ring by means of an air-supporting system.

Known Art 5 An aerial vehicle as described in the foregoing has been the object i of the International Patent Application WO 2022/200883 A1 of the same Applicant. Further improvements have been the object of the Italian Patent Application IT 10 2023 000010134 of the same Applicant, which was filed on the 19^th May 2023 and is still unpublished on the priority date of the present invention. Further solutions developed by the Applicant have been the object of the International Patent Application WO 2020/261102 A1 .

In the years to come, important developments are expected both in the field of Advanced Air Mobility (AAM), with particular reference to the electrical VTOL (eVTOL) systems and to hybrid systems for cargo transport, as well as in the field of personal aerial vehicles. The Applicant has carried out extensive research and experiences in this field, both as regards the structural features of the aerial vehicle and as regards the improvement of the aerial vehicle propeller units from the point of view of efficiency and silent operation, as well as the improvement of the systems for the in-flight sustainment of the aerial vehicle and for the in-flight manoeuvrability thereof.

However, the need is still felt for further improvements regarding all the aspects mentioned in the foregoing.

Object of the Invention

As a consequence, the invention aims at providing an aerial vehicle, particularly a personal aerial vehicle or a drone, which is equipped with improved, high-efficiency propeller units.

A further object of the invention is achieving said goal with simple, low-cost means.

A particularly meaningful object is increasing the silent operation of the propeller units that the aerial vehicle is equipped with.

A further, more specific goal of the present invention is improving the means for the air support of the rotor ring of each annular propeller unit that the aerial vehicle is equipped with.

A further object of the invention is providing a rotor assembly which, thanks to the high torque applied to the periphery thereof, enables a reduction of the rotor diameter with the same vertical lift and with the same power.

A further object of the invention is providing a new configuration of a propeller unit, having a structure configured for enabling a simple and rapid assembly of the components thereof.

A still further object of the invention is providing new configurations for the blades of the propeller that the aerial vehicle is equipped with, adapted to further improve efficiency and silent operation.

Moreover, a further object of the invention is providing a new type of propeller unit with blades carried by a central hub, which can be used e.g. for the tail rotor of the aerial vehicle, in the drones and in the eVTOL aerial vehicles, characterized by high efficiency and silent operation.

A still further object of the invention is providing a modular aerial vehicle structure, which can be rapidly converted in such a way as to achieve various configurations.

Summary of the Invention

With a view to achieving one or more of the objects outlined in the foregoing, the invention regards a personal aerial vehicle, or a drone, having the features which have been provided at the beginning of the present description, and moreover characterized in that:

- the stator ring and the rotor ring are configured in such a way as to define between them, on two opposite faces of the rotor ring, two circumferential pressure chambers, supplied with pressurized air, for airsupporting the rotor ring,

- each propeller unit comprises an electrically driven pump, configured to feed pressurized air into the two pressure chambers, and

- for each of said pressure chambers, a plurality of ducts are provided for feeding pressurized air coming from said pump to the respective pressure chamber, at a plurality of inlets arranged along the stator ring and circumferentially distributed along the latter.

In a preferred embodiment, the rotor ring has two substantially conical opposite faces, having depressed circumferential portions for defining said pressure chambers. Preferably, the stator ring has a radially inwardly concave shell configuration with two substantially conical opposite inner faces facing said opposite conical faces of the rotor ring and having depressed circumferential portions for defining said pressure chambers. Between the stator ring and the rotor ring there are interposed slip seal rings, for sealing each pressure chamber along an inner circumferential edge and along an outer circumferential edge of the circumferential pressure chamber.

Still referring to the preferred embodiment, the rotor ring comprises:

- a first outer annular element, rotationally supported by the stator ring, and

- a second inner annular element, rigidly mounted within the first outer annular element and defining the inner surface of the rotor ring from which the blades of the propeller unit extend, said blades being rigidly connected to said second inner annular element.

Thanks to this feature, the blades may be pre-assembled with said second inner annular element; subsequently, said second inner annular element may be rapidly mounted into the first outer annular element, so as to obtain the rotor ring of the propeller unit.

According to a first solution, one or more propeller units have blades which, when viewed in the direction of the axis of rotation, have a substantially triangular conformation, tapering radially inward, such that the area occupied by the blades, when viewed in the direction of the axis of rotation, constitutes a predominant portion of the area within the rotor ring. Each blade, when viewed radially from the outside, has an airfoil profile with a leading edge and a trailing edge, the direction of rotation of the rotor ring being such that the relative airflow first meets a leading edge of the blade and then a trailing edge of the blade. Preferably, either or both opposite faces of the blades have concentric circumferential ribs, spaced radially apart, to guide a relative airflow over the blades.

In contrast to what is known and possible with conventional blades, the characteristic of the blades of the annular rotors according to the invention is having the maximum cross section where the maximum velocity of peripheral rotation occurs.

In a variant, which may be used e.g. for the propeller unit mounted on the tail of the aerial vehicle, there is provided at least one propeller unit having a propeller with a central hub and a plurality of blades extending from the central hub. This solution is moreover characterized in that:

- the blades carried by the central hub are distributed over two or more axially overlapping and spaced layers, rotating together with the hub in the same direction,

- the blades of different layers are in identical angular positions, or in angular positions circumferentially offset from each other,

- the outer ends of corresponding blades belonging to different layers are rigidly connected to each other by connecting elements, having a circular arc configuration concentric with the hub,

- said connecting elements preferably define walls constituting portions of a tube coaxially surrounding the hub.

Also in the case of these variants, an embodiment is envisaged wherein the blades carried by the hub, when viewed in the direction of the axis of rotation, have a substantially triangular conformation, tapering radially inward, such that the area occupied by the blades, when viewed in the direction of the axis of rotation, constitutes a predominant portion of the entire area of the propeller unit. Preferably, either or both opposite faces of the blades have concentric circumferential ribs, spaced radially apart, to guide a relative airflow over the blades.

Thanks to the connecting elements, the blades constitute together a structure which reduces vibrations, and such that the cross section of the blades may be increased toward the periphery where the maximum velocity occurs.

In a further embodiment, the aerial vehicle comprises two or more propeller units carried by said discoidal upper wing.

In an embodiment, the aerial vehicle is moreover characterized in that:

- said front wings and said rear wings are integrated into a single allwing module in which a plurality of propeller units are arranged,

- said all-wing module is configured with a cargo hold,

- said all-wing module is configured to be also used on its own, but it is arranged to receive above it a cabin module, and

- said cabin module is in turn configured to receive said discoidal upper wing above it.

In a particularly preferred solution, the aerial vehicle is moreover provided with a system for the generation of directional jets for the control of the in-flight attitude of the aerial vehicle, and/or of thrust jets to provide additional lift and/or thrust to the aerial vehicle, according to what has been proposed in the previous Patent Application IT 10 2023 000010134 of the same Applicant, as will be better detailed in the following.

Detailed Description of the Invention

Further features and advantages of the invention will be apparent from the following description with reference to the annexed drawings, provided by way on non-limiting example only, wherein:

- Figure 1 is a perspective view of a personal aerial vehicle, of the type constituting the object of the International Patent Application WO 2022/200883 A1 of the same Applicant,

- Figure 2 is a perspective view of a propeller unit of an aerial vehicle according to the present invention,

- Figure 3 is a partially cross-sectional view of the propeller unit of Figure 2,

- Figure 4 is a further cross-sectional perspective view of the propeller unit of Figure 2,

- Figures 5-7 are a top view, a perspective view and an exploded perspective view of a first embodiment of the rotor ring of a propeller unit of the aerial vehicle according to the invention,

- Figures 8-10 are a top view, a perspective view and an exploded perspective view of the rotor ring of a propeller unit according to the invention, according to a second embodiment,

- Figure 11 shows a variant of Figure 8,

- Figures 12-16 are perspective views showing various embodiments of a propeller unit of the type including blades carried by a central hub, according to various embodiments (Figure 16 clearly shows that the cross section of the blade is maximum towards the periphery; the same technical feature may be implemented also in the solutions described in Figures 12- 15),

- Figure 17 is perspective view of a first embodiment of the aerial vehicle according to the invention,

- Figure 18 shows a variant of Figure 17,

- Figure 19 shows a further variant of Figure 17, with further rotors arranged on the upper wing, useful for enabling the transport of particularly heavy loads, - Figures 20, 21 are perspective views showing various configurations of an aerial vehicle according to the invention, having a modular structure reconfigurable by associating a plurality of modules with one another,

- Figures 22A, 22B and 23A, 23B show a configuration with enlarged wings and with rotors the axis of rotation whereof is inclined outwards, in order to avoid an interference with the upper wing and to maximize the vertical thrust, and

- Figures 24 and 25 show the configuration of an autonomous aerial vehicle for environmental surveillance and monitoring, with a very small cabin to accommodate monitoring equipment.

Figure 1 shows, by way of example, a personal aerial vehicle on which it is possible to apply the principles underlying the present invention. The exemplary aerial vehicle shown in Figure 1 is generally of the type which constitutes the object of the Internation Patent Application WO 2022/200883 of the same Applicant.

The aerial vehicle, generally denoted by reference 1 , has a supporting structure consisting in a steel framework (not visible in the drawing), which defines a central body B containing a cockpit C, two front wings W and two rear wings R. The walls of the central body B and of the wings W, R consist of steel sheet elements rigidly connected to the framework. Preferably, the inner cavity of the aerodynamic surfaces is filled with a spongy material, preferably graphene. The panels of the aerial vehicle may be made of a thermoplastic material, which is a lightweight material, as an alternative to the panels of carbon fibre composite material, thereby reducing the problems connected to manufacturing costs and recyclability/sustainability.

In the preferred example described herein, the central body B supports above it, by means of arms 3, an additional wing WX having a substantially discoidal shape in top view, so as to obtain the best aerodynamic performances in all flight conditions. The upper surface of the upper wing WX is also used to carry a plurality of solar cells F, adapted to generate energy which may be used to recharge the electric batteries on board. Also the outer surfaces of the central body B and of the wings W, R may be used for the arrangement of solar cells thereon. According to a solution which constitutes the object of the International Patent Application WO 2022/200883 A1 , within the front wings W and within the rear wings R there are arranged annular propeller units P (i.e., propeller units without a central hub, the blades L being carried by a rotor ring and having their free ends near the axis of the rotor, but spaced apart therefrom), carried by the supporting structure of the aerial vehicle and having substantially vertical axes of rotation (with reference to the ground- supported condition of the aerial vehicle), in order to enable the in-flight sustainment of the aerial vehicle. In order to maximize the vertical thrust, the axis of rotation of the rotors may be inclined outwards. In this way, the air flowing downwards through the rotors does not interfere with the upper wing. As a second effect of the inclination of the rotors, the air flows converge towards the base of the aerial vehicle, thus favouring the thrust upwards. Moreover, the tail of the central body B supports a stator ring S, arranged with its axis substantially parallel to the longitudinal direction of the aerial vehicle. Within the stator ring S there is rotatably mounted the rotor ring of a further annular propeller PX.

Still referring to the known art of the International Patent Application WO 2022/200883 A1 , each annular propeller P, PX comprises a rotor ring carrying blades L which extend radially from the body of the rotor ring towards the axis of the rotor ring. Still according to the known art identified in the foregoing, the rotor ring of each annular propeller P, PX is rotationally controlled via a belt drive (which will be detailed in the following with reference to the embodiments of the present invention) by a respective electric motor, having an axis which is parallel to and spaced apart from the axis of the rotor ring associated therewith.

Still referring to Figure 1 , the central body B of the aerial vehicle is preferably provided with lower legs D, which are flexible and/or withdrawable for resting on the ground.

Figures 2-4 show an improvement of the annular propeller unit forming the object of the present invention. This solution is characterized by an improved system for the air supporting of the rotor ring RO.

With particular reference to Figure 3, in this example the stator ring S has a radially inwardly concave shell configuration defined by two annular bell-shaped elements 4, having outer circumferential flanges 5 which are rigidly connected with each other (e.g. welded or glued or riveted).

Within the cavity of the stator ring S there is arranged the rotor ring RO, which has a cylindrical inner surface 6 from which the blades L extend, being rigidly connected to the rotor ring RO.

In the present example, the rotor ring RO has two substantially conical opposite faces having depressed circumferential portions 7 for defining, together with the stator ring S, two pressure chambers 8 which are supplied with pressurized air (in a fashion which will be better detailed in the following). The conical opposite faces of the rotor ring RO, of course, have their axis coincident with the common axis of the stator ring S and of the rotor ring RO.

Also the stator ring S has two substantially conical opposite faces, although their axis coincides with the axis of the rotor assembly RO, having depressed portions 9 facing the depressed portions 7 of the rotor ring RO, in order to define the two pressurized circumferential chambers 8.

As can also be seen in Figure 3, the rotor ring RO has a substantially cylindrical outer surface, having a groove 10 with trapezoidal cross section for engaging a belt T with trapezoidal cross section for actuating the rotation of the rotor ring RO.

As can be seen in Figures 2, 4, the belt T is guided through two openings 11 of the stator ring S (only one of them being visible in Figure 2), so that a belt portion is outside the stator ring S and engages an actuation pulley 2, which is controlled (preferably by means of a gear transmission) by an electric motor M the axis whereof is parallel to and spaced apart from the axis X of the propeller unit P.

In an alternative configuration, the single belt may be replaced by two independent belts, operating with a pulley having two, either smooth or toothed, pulley grooves.

As can be seen particularly in Figure 2, each propeller unit P has, associated therewith, an electrically driven pump 12 for supplying pressurized air to the two pressurized circumferential chambers 8, in order to rotatably support the rotor ring RO by means of an air supporting system.

For each pressure chamber 8 there is provided a plurality of air supply ducts 80, which feed pressurized air from the pump 12 to a plurality of inlets 81 arranged circumferentially along the stator ring S and communicating with the circumferential chambers 8.

Still referring to Figure 3, between the rotor ring RO and the stator ring S there are interposed slip seal rings 13, respectively along the inner circumferential edge and along the outer circumferential edge of each circumferential chamber 8, to ensure maintaining a given level of air pressure within the chambers 8.

In this way, the rotor ring RO is rotatably supported by means of the air supports provided by the pressure chambers 8, with minimum friction losses deriving from the seal rings 13.

Figures 5-7 show a first embodiment of the propeller unit P with blades L having a substantially conventional configuration, except for the fact that they have an end portion with rapidly increasing twist. The exploded perspective view of Figure 7 clearly shows the simplicity of assembling the propeller unit. It must be noted that the three blades may be pre-assembled on an auxiliary ring (not shown in Figure 7) which may subsequently be mounted into the rotor ring RO. In other words, the invention envisages that the rotor ring RO is made by two concentric annular elements: a first outer annular element, rotationally supported by the stator ring S, and a second inner annular element, rigidly mounted within the first outer annular element and defining the inner surface of the rotor ring wherefrom the blades L extend, said blades being rigidly connected to said second inner annular element. The configuration of the rotor ring RO with two annular elements assembled together is clearly visible in Figure 10, with reference to a further embodiment. Figures 8, 9 are a top view of the propeller unit according to Figure 10, whereas Figure 9 shows a perspective view only of the blades belonging to the propeller unit according to such further embodiment.

In this embodiment each blade L, when viewed in the direction of the axis of rotation (i.e. as in Figure 8) has a substantially triangular conformation, tapering radially inward, such that the area occupied by the blades, when viewed in the direction of the axis of rotation (as in Figure 8), constitutes a predominant portion of the area within the rotor ring. Moreover, in this embodiment, either or both opposite faces of the blades L have concentric circumferential ribs N, spaced radially apart, configured to guide a relative airflow over the blades, i.e. the airflow which moves relatively with respect to the blades L due to the rotation of the rotor ring RO. In this way, the relative airflow meets each blade L in ideal conditions, in order to maximize the propeller efficiency.

Referring to figure 9, each blade L, when viewed radially from outside, has an airfoil profile 15 with a leading edge 15A and a trailing edge 15B. Therefore, with reference to Figure 9, the direction of rotation of the rotor ring is the direction denoted by the arrow V, so that the relative airflow first meets the leading edge 15A of each blade L and then the trailing edge 15B thereof.

The structure of the propeller unit visible in Figure 10 is similar to the structure in Figure 7, with the exception that, in this case, Figure 10 explicitly shows an inner annular element 16, which carries the blades L and which may be assembled into an outer annular element 17 which, together with the inner annular element 16, constitutes the rotor ring RO. The configuration of the elements 9 constituting the stator ring S is identical to the one previously described.

Figure 11 shows a variant of Figure 8, wherein the circumferential extension of the blades L is further enlarged, so that the surface occupied by the blades L, when viewed in the direction of the axis of rotation (as in Figure 11 ) occupies almost the entire inner area of the rotor ring.

Figures 12-16 show further embodiments of a propeller unit which may be used in the aerial vehicle according to the invention, e.g. particularly for the tail rotor. All the embodiments of Figures 12-16 are characterized in that they have conventional blades L, which extend radially from a central hub H.

All the embodiments of Figures 12-16 are characterized in that the blades L carried by the central hub H are distributed over two or more axially overlapping and spaced layers, rotating together with the hub H in the same direction. The blades L of different layers are in identical angular positions (see Figures 12 and 16), or in angular positions circumferentially offset from each other (13-15). The optimum axial distance between the layers and the relative angular positions are defined as a function of the rotational speed, of the profile and of the angle of attack of the blades.

A further feature which is common to all the embodiments of Figures 12-16 resides in the fact the outer ends of the blades L of different layers which are in corresponding (identical or offset) angular positions are rigidly connected to each other by connecting walls 18 having an arc configuration, along arcs of a circle concentric with the axis of the central hub H.

The connecting walls 18 may have a substantially small cross-section (see Figures 12-14), or they may have a dimension in the direction of the axis of rotation which is considerably higher than the corresponding dimension of the outer ends of the blades L (see Figures 15, 16), in such a way as to form guide walls for the airflow, substantially corresponding to portions of a tubular wall concentric with the central hub H.

The distinctive feature of this connection of the blades leads the latter to form a more rigid structure, which enables enlarging the section of the blade towards the outside, where the blade turns at the maximum peripheral velocity. This enables applying a higher torque to the motor and increasing the angle of attack of the propellers. Thanks to this feature, it is possible to increase the mass of the airflow through the rotor, therefore increasing the upward thrust without increasing the downward airflow velocity.

Figure 16 shows an embodiment wherein the blades L of each layer have a substantially triangular configuration, tapering radially towards the hub H, so that the area occupied by the blades L, when viewed in the direction of the axis of rotation, constitutes a predominant portion of the entire area occupied by the propeller unit. Also in this case, preferably, one or both opposite faces of the blades L have concentric circumferential ribs N, spaced radially apart, to guide the relative airflow over the blades L.

Figures 17, 18 show an aerial vehicle according to the present invention, having a general configuration substantially similar to the configuration in Figure 1 . In these Figures, at one of the propeller units having a vertical axis and at the tail propeller unit, there are shown different rotor configurations, among which it is possible to select the configuration to be used. Of course, only one of the propeller units shown will be used in every specific aerial vehicle configuration. The relative speed of rotation between the rotors defines the roll, pitch and yaw angles, according to known techniques. Always according to known techniques, the speed of the rotors, and therefore the stability, the elevation and the orientation in space of the aerial vehicle are controlled by one or more multiaxial MEMS inertial platforms.

Figure 19 shows a further embodiment, wherein the discoidal upper wing WX has further propeller units P, in the number of one or two, associated therewith.

Figures 22A, 22B and 23 show a configuration with enlarged wings and rotors the axis of rotation whereof is inclined outwards, in order to avoid an interference with the upper wing and to maximize the vertical thrust.

Figures 24 and 25 show the configuration of an autonomous aerial vehicle for environmental surveillance and monitoring, with a very small cabin to accommodate monitoring equipment.

Figures 20, 21 refer to a further embodiment of the aerial vehicle according to the invention, having a general modular configuration which is rapidly reconfigurable by associating one or more modules. In this case, a base module M1 is provided which has an all-wing configuration, which integrates the front wing and the rear wing of the aerial vehicle of Figures 1 , 17, 18. The base module M1 integrates the propeller units P implemented according to any of the solutions described in the foregoing.

Moreover, the base module M1 is provided with a hollow structure defining a cargo hold.

As shown in Figure 21 , the base module M1 may be provided with a second module M2 defining the cabin B of the aerial vehicle. Moreover, above the second module M2 it is possible to mount a discoidal upper wing WX of the type shown in Figures 1 , 17, 18 and 19. According to a further preferred feature of the invention, the aerial vehicle 1 may be provided with a system for the emission of directional jets to control the in-flight attitude of the aerial vehicle, and/or with thrust jets to provide additional lift and/or thrust and/or to control the roll, pitch and yaw movements, as in the object of the previous Italian Patent Application IT 102023000010134 of the same Applicant, which has already been mentioned in the foregoing. According to such a solution, the supporting structure of the aerial vehicle carries a plurality of nozzles distributed along the front wings and at the rear of the aerial vehicle, for the emission of said directional jets and/or thrust jets. Each nozzle includes a nozzle chamber and a jet outlet, communicating with the nozzle chamber. The jet generation system includes:

- a pressurized fuel supply system to the nozzle chambers, and

- a pressurized combustion fluid supply system to the nozzle chambers. The fuel supply system includes:

- a plurality of electromagnetically operated injector devices, each associated with a respective nozzle,

- a tank of fuel to be fed to the injector devices,

- a pump, electronically controlled, to bring fuel from the tank to a predetermined pressure, suitable for the operation of the injector devices,

- a distribution manifold, that receives pressurized fuel from the pump and feeds it to the injector devices through respective conduits,

- an electronic controller configured to receive pressure information in the distribution manifold and to control the high-pressure pump so as to maintain a pressure in the distribution manifold within a predetermined range of values.

The electronic controller is configured to operate the injector devices independently of each other, to inject high-pressure fuel into the chamber of each nozzle, in order to obtain a mixture with the combustion fluid that gives rise to a compression combustion, with a consequent deflagration which generates a jet of high-pressure fluid exiting the nozzle.

The implementation details of the fuel supply system are not illustrated herein, given that such a system may be implemented similarly to what is already known in the field of fuel injection systems for internal combustion engines. This applies both for the fuel injectors, which may be configured in any possible known fashion, according to the technology of the fuel injectors for internal combustion engines, and for the distribution manifold (also known as Tail”), as well as for the high-pressure pump associated therewith.

Unlike the automotive application mentioned in the foregoing, in the case of the aerial vehicle according to the present invention the regulation of the jet thrust, i.e. the frequency of opening/closing the injectors, is implemented by means of the signals received by one or more multiaxial MEMS inertial platforms. In this way the roll, pitch and yaw angles, and therefore the stability, the elevation and the orientation in space of the aerial vehicle, are regulated independently in a very short time, in the order of few milliseconds.

Some of the features which have been illustrated in the present description are also adapted to constitute independent and separate inventions.

For example, according to a further aspect, the invention regards an annular propeller unit, with a stator ring and a rotor ring rotatable inside the rotor ring and carrying a plurality of blades, wherein the blades have a substantially triangular conformation, tapering radially inward, such that the area occupied by the blades, when viewed in the direction of the axis of rotation, constitutes a predominant portion of the area within the rotor ring. Each blade, when viewed radially from the outside, has an airfoil profile with a leading edge and a trailing edge, the direction of rotation of the rotor ring being such that the relative airflow first meets a leading edge of the blade and then a trailing edge of the blade. Preferably, one or both opposite faces of the blades have concentric circumferential ribs, spaced radially apart, to guide a relative airflow over the blades.

Another separate and independent invention may consist in providing a propeller unit according to the principles underlying the solutions shown in Figures 12-16, wherein the propeller unit has a central hub H and a plurality of blades L extending from the central hub, wherein the blades carried by the central hub are distributed over two or more axially overlapping and spaced layers, rotating together with the central hub H in the same direction, wherein the blades of different layers are in identical angular positions or in angular positions circumferentially offset from each other, wherein the outer ends of blades belonging to different layers and being in equal or corresponding angular positions are rigidly connected to each other by connecting elements having a circular arc configuration concentric with the hub, and wherein the connecting elements preferably define walls constituting tube portions coaxially surrounding the hub.

Another embodiment adapted to constitute an independent and separate invention is illustrated with reference to Figures 20, 21 , wherein the structure of the aerial vehicle includes a base module constituting an allwing module M1 , which integrates the propeller units of the aerial vehicle and includes a cargo hold, said all-wing module being configured to be used on its own or to receive above it a cabin module M2, which can in turn receive a further module constituting a discoidal upper wing WX arranged above the cabin module M2.

As it is clear in the light of the description provided in the foregoing, the various solutions proposed according to the present invention share the common goal of increasing the efficiency and the silent operation of the propeller units with extremely simple and low-cost means. The solutions proposed with the present invention pave the way to new and advantageous applications in the field of personal aerial vehicles and in the field of drones, especially cargo drones. Finally, the invention also achieves the goal of enabling large scale production at considerably lower cost.

Of course, without prejudice to the principles of the invention, the implementation details and the embodiments may amply vary with respect to what has been described and illustrated by way of example only, without departing from the scope of the present invention as defined in the annexed claims.

Claims

1 . A personal aerial vehicle, or drone, comprising:

- a supporting structure, defining a central body (B) with front wings (W) and rear wings (R),

- a plurality of annular propeller units (P), having substantially vertical axes of rotation (X), with reference to the ground-supported condition of the aerial vehicle, and located in the front wings (W) and rear wings (R) of the aerial vehicle, for in-flight sustainment of the aerial vehicle, and

- at least one propeller unit (PX) carried by a tail of the central body (B), having an axis of rotation substantially parallel to the longitudinal direction of the aerial vehicle, to propel the aerial vehicle forward in flight, and

- an additional upper wing (WX) in the form of a disc, arranged above the central body (B), wherein each annular propeller unit comprises:

- a stator ring (S) rigidly connected to an aerial vehicle support structure,

- a rotor ring (RO) rotatably mounted coaxially within the stator ring (S), having a radially internal surface (6) that is substantially cylindrical,

- one or more blades (L) extending radially from said inner surface of the rotor ring (RO), toward the axis (X) of the rotor ring,

- at least one power unit (M) carried by an aerial vehicle supporting structure and having an output shaft spaced from the axis (X) of the rotor ring (RO) and connected to the rotor ring (RO) by a belt drive (T),

- wherein the rotor ring (RO) is rotatably supported by the stator ring (S) by means of an air-supporting system, said aerial vehicle being characterized in that:

- the stator ring (S) and the rotor ring (RO) are configured in such a way as to define between them, on two opposite faces of the rotor ring (RO), two circumferential pressure chambers (8), supplied with pressurized air, for air-supporting the rotor ring (RO),

- each propeller unit (P) comprising an electrically driven pump (12), configured to feed pressurized air into the two pressure chambers (8), and - for each of said pressure chambers (8), a plurality of ducts (80) being provided, for feeding pressurized air from said pump (12) to the pressure chamber (8), at a plurality of inlets (81 ) arranged along, and circumferentially distributed along, the stator ring (S).

2. An aerial vehicle according to claim 1 , characterized in that said rotor ring (RO) has two substantially conical opposite faces having an axis coincident with the axis of the rotor ring (RO), and having depressed circumferential portions (7) for defining said pressure chambers (8), and preferably in that said stator ring (S) has a radially inwardly concave shell configuration with two substantially conical opposite inner faces facing said opposite faces of the rotor ring (RO) and having depressed circumferential portions (9) for defining said pressure chambers (8), and in that between the stator ring (S) and the rotor ring (RO) there are interposed slip seal rings (13) for sealing each pressure chamber (8) along an inner circumferential edge and along an outer circumferential edge of the circumferential pressure chamber (8).

3. An aerial vehicle according to claim 1 , characterized in that the rotor ring (RO) comprises:

- a first outer annular element (17), rotationally supported by the stator ring (S), and

- a second inner annular element (16), rigidly mounted within the first outer annular element (17) and defining the inner surface (6) of the rotor ring (RO) from which the blades (L) of the propeller unit extend, said blades being rigidly connected to said second inner annular element (16).

4. An aerial vehicle according to claim 1 , characterized in that the axis of rotation of the propeller units (P) is inclined at an angle of the order of 10 degrees from the vertical upwardly and laterally outwardly and 5 degrees to the front.

5. An aerial vehicle according to claim 1 , characterized in that:

- one or more propeller units have blades (L) which, when viewed in the direction of the axis of rotation (X), have a substantially triangular conformation, tapering radially inward, such that the area occupied by the blades, when viewed in the direction of the axis of rotation, constitutes a predominant portion of the area within the rotor ring (RO),

- each blade (L), viewed radially from the outside, has an airfoil profile (15) with a leading edge (15A) and a trailing edge (15B), the direction of rotation of the rotor ring being such that the relative airflow first meets the leading edge (15A) of the blade and then the trailing edge (15B) of the blade, and preferably one or both opposite faces of the blades (L) have concentric circumferential ribs (N), spaced radially apart, to guide a relative airflow over the blades (L).

6. An aerial vehicle according to claim 1 , characterized in that: the propeller units (P) are controlled by one or more MEMS inertial platforms to control the attitude-orientation in space and the roll, pitch, yaw angles of the aerial vehicle.

7. An aerial vehicle according to claim 1 , characterized in that:

- one or more propeller units, preferably the tail propeller unit, have a propeller with a central hub (H) and a plurality of blades (L) extending from the central hub (H),

-wherein the blades (L) carried by said central hub (H) are distributed over two or more axially overlapping and spaced layers, rotating together with the hub (H) in the same direction,

- wherein the blades (L) of different layers are in identical angular positions or in angular positions circumferentially offset from each other,

- the outer ends of corresponding blades belonging to different layers are rigidly connected to each other by connecting elements (18), having a circular arc configuration concentric with the hub (H), so that the blades have a larger cross section toward the periphery where the maximum angular velocity occurs, and so that the blades, due to their greater stability, can have a greater angle of attack and therefore can generate a greater airflow without increasing the air velocity, i.e. can maximize the upward thrust without increasing the downward air flow velocity and without requiring increased motor power,

- said connecting elements (18) preferably defining a wall constituting a portion of tube coaxially surrounding the hub (H).

8. An aerial vehicle according to claim 7, characterized in that the axial distance between the layers and the angular offset of the blades (L) of the different layers are chosen according to the diameter, rotational speed and angle of attack of the blades.

9. An aerial vehicle according to claim 7, characterized in that the blades carried by said hub (H), viewed in the direction of the axis of rotation have a substantially triangular conformation, tapered radially inwardly, such that the area occupied by the blades (L), viewed in the direction of the axis of rotation (X), constitutes a prevailing portion of the entire area of the propeller unit, and by the fact that preferably one or both of the opposite faces of the blades (L) have concentric circumferential ribs (N), spaced radially apart, to guide a relative airflow over the blades (L).

10. An aerial vehicle according to claim 1 , characterized by comprising two or more propeller units (P) carried by said discoidal upper wing (WX).

11 . An aerial vehicle according to claim 1 , characterized in that:

- said front wings and said rear wings are integrated into a single allwing module (M1 ) in which a plurality of propeller units (P) are arranged,

- the all-wing module (M1 ) is configured with a cargo hold,

- the all-wing module (M1 ) is also configured to be used on its own, but is arranged to receive above it a cabin module (M2) that is relatively larger in size if it is intended to accommodate one or more persons seated in rows, and relatively smaller if it is intended to accommodate control devices,

- said cabin module (M2) is configured to receive a discoidal upper wing (WX) above it.

12. An aerial vehicle according to claim 1 , characterized in that: - the support structure carries a plurality of nozzles distributed along the front wings and at the rear of the aerial vehicle, for the emission of thrust jets to provide additional lift and/or thrust to the aerial vehicle and/or directional jets for quick control, in the order of milliseconds, of the orientation in space, and the elevation and stability in the roll, pitch and yaw movements of the aerial vehicle (1 ), with the aid of one or more MEMS inertial platforms,

- each nozzle includes a nozzle chamber and a jet outlet, communicating with the nozzle chamber,

- the aerial vehicle is equipped with a jet generation system, including:

- a pressurized fuel supply system to the nozzle chambers, and

- a pressurized combustion fluid supply system to the nozzle chambers,

- wherein the fuel supply system includes:

- a plurality of electromagnetically operated injector devices each associated with a respective nozzle,

- a tank of fuel to be fed to the injector devices,

- a pump, electronically controlled, to bring fuel from the tank to a predetermined pressure suitable for the operation of the injector devices,

- a distribution manifold that receives pressurized fuel from the pump and feeds it to the injector devices through respective conduits,

- an electronic controller configured to receive pressure information in the distribution manifold and to control said high-pressure pump so as to maintain a pressure in the distribution manifold within a predetermined range,

- said electronic controller being configured to operate said injector devices independently of each other, to inject high-pressure fuel into the chamber of each nozzle in order to obtain a mixture with the fuel fluid that gives rise to a compression combustion with a consequent deflagration that generates a jet of high-pressure fluid exiting the nozzle.