WO2024117891A1

WO2024117891A1 - An unmanned aerial vehicle with a variable gap duct unit

Info

Publication number: WO2024117891A1
Application number: PCT/LV2023/050017
Authority: WO
Inventors: Janis DOBELIS
Original assignee: Topspin Robotics, Sia
Priority date: 2022-12-02
Filing date: 2023-11-24
Publication date: 2024-06-06

Abstract

The present invention relates to aerial vehicles, especially to unmanned aerial vehicles (UAV) having ducted fan. The UAV (1) comprises a body that defines a duct (2) enclosed by a duct wall (3), at least one fan electric motor (4) and at least one fan (5) positioned within the duct (2) in result of which a thrust (T) is generated. The UAV (1) is characterized in that it comprises at least two variable gap duct units (10). Each variable gap duct unit (10) comprises an opening (11) in the duct wall (3), a lid (12) covering said opening (11) and configured to open and close the opening (11), and an actuator (13) configured to drive the lid (12) from a closed position to an open position and back. The opening (11) is arranged at the same level, where the fan (5) is positioned.

Description

AN UNMANNED AERIAL VEHICLE WITH A VARIABLE GAP DUCT UNIT

DESCRIPTION

Field of the invention

[001] The present invention relates to aerial vehicles, especially to unmanned aerial vehicles having a ducted fan.

Background of the invention

[002] Unmanned aerial vehicles (UAVs) perform various tasks including aerial surveillance for military, civilian and commercial purposes. UAVs may have at least one ducted fan and a fan engine or motor to drive the fan. Ducted fan air- vehicles are well-known for performance capability in multiple flight conditions. For instance, ducted fan air- vehicles have the ability of forward flight and are well known for stationary hovering aerodynamic performance.

[003] Typical UAV with a ducted fan is disclosed in US patent publication No. US 8,240,597. The UAV comprises an air duct and a fan located within the air duct. The UAV further comprises a centre body in the form of a housing that contains other components of the UAV. The centre body contains an engine for powering the UAV. The UAV also comprises fixed and/or movable vanes for providing thrust vectoring for said UAV. The vanes are located under the fan located within the air duct. For instance, the vanes may be placed slightly below an exit section of the air duct.

[004] The US patent publication No. US 5,152,478 discloses an UAV comprising two counterrotating rotors positioned within a toroidal shroud or fuselage in which rotor pitch change is utilised to generate all required lift, pitch, roll and yaw control. Rotor pitch change requires complex mechanical structure which increases overall weight and complexity of the UAV. The US patent publication No. US 4,795,111 discloses an UAV that uses a single propeller to direct air through a single duct for generating lift. The single duct has multiple vanes and spoilers that act together to control the flight path of the UAV. At least the spoilers are positioned within the single duct, which may reduce the air flow therethrough and the lift capabilities of this UAV.

[005] The US patent publication No. US 10,625,858 discloses an UAV comprising a body that defines a duct and at least one fan for creating an airflow, and at least two flaps installed on the body and configured to drive, to change a direction, a pressure and a rate of the airflow at the lower end of the duct. The flaps protrude out from the body and into an area of the duct and at the lower area of the duct. The US patent application publication No. US2019/185161 discloses an UAV that comprises a semi-toroidal or a substantially toroidal hollow body that defines a duct. The UAV further comprises a motor for rotating a fan that directs air into and out of the duct enabling the UAV to take flight. The UAV comprises a flight-control system that comprises at least two flight control surfaces that can alter the directed air as it flows through the duct for controlling the roll and pitch and optionally the yaw of the UAV during flight.

Summary of the invention

[006] The present invention takes advantage of a phenomena that a fan or propeller shrouded by a duct provides more thrust per fan area occupied compared to an open propeller. Ducted fan propulsion is often more energy efficient for predominantly hovering UAVs - more static thrust per energy spent compared to UAV with open rotor propulsion. Efficiency gain is related to reduction of tip losses occurring on the outer side of the propeller. The duct helps to greatly reduce tip vortex generation on a spinning fan or propeller. This phenomena is dependent on the gap size between propeller tip and duct wall. By varying the gap size between the propeller tip and duct wall, the one can alter the resultant thrust vector of the fan or propeller. By altering the thrust vector location, the one can achieve UAV attitude control.

[007] The present invention is an UAV comprising a body that defines a duct enclosed by a duct wall with an upper end and a lower end that is opposite to the upper end, a vertical axis extending through a centre of the duct and from the upper end to the lower end. The UAV comprises at least one fan electric motor and at least one fan positioned within the duct and operatively coupled to the at least one electric motor for rotating the at least one fan and generating an airflow into the upper end of the duct and out of the lower end of the duct, in result of which a thrust is generated. The UAV comprises a flight controller attached to the body of the UAV. The flight controller is electronically connected to the fan electric motor and to the actuator. The flight controller is configured to control the fan electric motor for generating the necessary thrust for the UAV and to control the actuator to open or close the lid for providing necessary roll and pitch of the UAV.

[008] The UAV is characterised in that it comprises at least two variable gap duct units. Each variable gap duct unit comprises an opening formed in the duct wall, a lid covering the opening and configured to be movable from a closed position, wherein the lid closes the opening, to an open position, wherein the lid is retracted or moved away from the opening. The movement of the lid away from the opening is in a direction away from the central or vertical axis of the UAV. Hence, the lid and the variable gap duct unit itself does not restrict or spoil the airflow within the duct. The variable gap duct unit comprises an actuator operatively connected to the lid and configured to drive the lid from the closed position to the open position and back. The actuator is configured to receive one or more instructions from the flight control system to control a pitch and a roll of the UAV during flight by opening and closing respective lid. Each opening of the variable gap duct unit in relation to the vertical axis is arranged at the same level, where a tip of a blade of the fan is positioned so that the thrust can be changed at the section of the duct where the lid is located. Opening of the lid, which is part of the duct wall when the lid is closed, varies the gap size between the fan blade tip and the lid, which can be considered as variation of the gap size between the fan blade tip and the duct wall. As a result of this variation of the gap size the resultant thrust vector of the fan or propeller is altered.

[009] The actuator may be any mechanism known to the skilled person that can open the lid from the opening as well as close the opening by the same lid and hold the same lid on the opening so that the opening is closed and sealed. One of the solutions may be the actuator comprising a lid electric motor with a drive or rotation axis. The lid electric motor is secured to the body of the UAV. The lid electric motor is connected to the lid by means of a lever arm connected to an rotation axis of the lid electric motor and a lid control arm hingedly connected to the lever arm and to the lid so that in a result of a rotation of the rotation axis of the lid electric motor in one direction the lid is brought into the open position and a rotation of the rotation axis of the lid electric motor in opposite direction the lid is brought into closed position. [010] The lid itself may be hingedly connected to the body of the UAV. The lid comprises a hinge that is hingedly connected to the body of the UAV via a hinge axis so that the lid is opened or closed by a movement of the hinge around said hinge axis. The lid connection to the body of the UAV may be accomplished also by other means of mechanical linkages

[Oi l] The lid may further comprise a flange extending around an edge of the lid so that the flange extends over an edge of the opening providing additional coverage of the opening by the lid. This feature provides additional safety that the opening in the duct wall will be fully closed by the lid being in a closed position.

[012] Various embodiments of the invention are possible having multiple fans, multiple ducts with fans, two, three, four or more variable gap duct units depending on a configuration of the UAV. One of such configurations may be an UAV in a bi-copter configuration. [013] The present invention also discloses a method for controlling a pitch and roll authority on the UAV as described above. The pitch and roll is controlled by opening the opening in the duct wall on a side of the duct wall, on which a pitch or roll movement is necessary, as the opening of the respective opening decreases a lift on that respective side of the opening and the unmanned aerial vehicle rolls or pitches on that respective side. The pitch and roll may be also controlled simultaneously by opening at least two adjacent openings in the duct wall on a side of the duct wall, on which a resultant pitch or roll movement is necessary, as the opening of the respective adjacent openings decreases a lift on that respective side of both openings and the unmanned aerial vehicle rolls or pitches on that respective side. The method utilises the phenomena of ducted fan thrust change near sections of the duct where the gap between fan tip and duct wall is changed.

Brief description of the drawings

[014] Fig. 1 is a top perspective view of an unmanned aerial vehicle (UAV) (1).

[015] Fig. 2 is a bottom perspective view of the UAV (1) as seen in Fig. 1, but from a different angle.

[016] Fig. 3 is a side perspective view of the UAV (1) as seen in Figs. 1 and 2.

[017] Fig. 4 is a bottom view of the UAV (1) as seen in Figs. 1 to 3.

[018] Fig. 5A is a cross-section view of the UAV (1) with fully closed openings (11) in the duct wall (3).

[019] Fig. 5B is a cross-section view of the UAV (1) with a substantially open opening (11) in the duct wall (3) forming an enlarged gap between a tip (52) of a blade (51) of a fan (5) and the duct wall (3).

[020] Fig. 6 is a perspective and cross -sectioned view of the UAV (1) showing one of the openings (11) in the duct wall (3) being in a substantially open position.

[021] Fig. 7A is a cross-section top view of the UAV (1) showing all four openings (11) closed by each respective lid (12).

[022] Fig. 7B is a cross-section top view of the UAV (1) showing one of four openings (11) substantially open forming enlarged gap between the tip (52) of the blade (51) of the fan (5) and a duct wall (3) or the lid (12) itself as the lid (12) is moved away from the opening (11) and the tip (52) of the blade (51) of the fan (5). [023] Fig. 8A is cross-section view of the UAV (1) illustrating equal or symmetric distribution of a lift when the openings (11) are closed and there is no gap increase between the tip (52) of the blade (51) of the fan (5) and a duct wall (3).

[024] Fig. 8B is cross-section view of the UAV (1) illustrating unequal or asymmetric distribution of a lift when the opening (11) on one side is open or not covered by a lid (12), and enlarged or increased gap is formed between the tip (52) of the blade (51) of the fan (5) and a duct wall (3).

[025] Fig. 9 is a top perspective view of another embodiment of an UAV (1) comprising three variable gap duct units (10).

[026] Fig. 10 is a top perspective view of the UAV (1) with a cross sectioned duct wall (3) as seen in Fig. 9.

[027] Fig. 11 is a top perspective view of another embodiment of an UAV (1) comprising two coaxially placed fans (5) and three variable gap duct units (10).

[028] Fig. 12 is a cross-section view of the UAV (1) as seen in Fig. 11.

[029] Fig. 13 is a top perspective view of another embodiment of an UAV (1) in a bi-copter configuration.

Detailed description of preferred embodiments

[030] Figs. 1 to 8B illustrate one embodiment of an unmanned aerial vehicle (UAV) (1).

[031] Figs. 1 to 6 illustrate the UAV (1) comprising a body (100) that defines a duct (2) enclosed by a duct wall (3) with an upper end (2A) and a lower end (2B) that is opposite to the upper end (2A), a vertical axis (X) extending through a centre of the duct (2) and from the upper end (2 A) to the lower end (2B). In the present embodiment the body (100) is a structure of the UAV (1) that carries elements or units of the UAV (1). The UAV (1) comprises one fan electric motor (4) arranged on the vertical axis (X) of the UAV (1). The UAV (1) comprises one fan (5) positioned within the duct (2) and operatively coupled to the one electric motor (4) for rotating the one fan (5) and generating an airflow into the upper end (2A) of the duct (2) and out of the lower end (2B) of the duct (2) in result of which a thrust (T) is generated. The fan (5) comprises four blades (51) with its respective four tips (52). The UAV (1) further comprises a stator (33). Stator (33) comprises four blades. Stator (33) serves the purpose of holding the electric motor (4) and may also serve to aerodynamically affect the airflow to gain more thrust (T). For example, stator (33) blades may recover some swirl from the stream after the fan (5). The UAV (1) comprises a flight controller (30) attached to the body (100) of the UAV (1). The flight controller (30) is electronically connected to the fan electric motor (4) and to the actuator (13). The flight controller (30) is configured to control the fan electric motor (4) for generating the necessary thrust (T) for the UAV (1) and to control the actuator (13) to open or close the lid (12) for providing necessary roll and pitch of the unmanned aerial vehicle (1). The UAV (1) comprises batteries (31) electrically connected to the flight controller (30), the fan electric motor (4) and the actuator (13). The UAV (1) also comprises an auxiliary compartment (32) for holding various auxiliary systems, like, camera, height sensors and other sensors well known to the skilled person in the field of the UAVs.

[032] The UAV (1) is characterised in that it comprises four variable gap duct units (10) allowing to change the gap between the tips (52) of the blades (51) of the fan (5) and the duct wall (3), in result of which a lift is disturbed in region or regions of increased gap and control of pitch and roll is accomplished. Each variable gap duct unit (10) comprises an opening (11) in the duct wall (3), a lid (12) covering the opening (11) and an actuator (13) operatively connected to the lid (12) and configured to drive the lid (12) from the closed position, wherein the lid (12) closes the opening (11), to the open position, wherein the lid (12) is retracted from the opening (11), and back. This retraction of the lid (12) is generally a movement of the lid in a direction away from the vertical axis (X) of the UAV (1). Each lid (12) comprises a flange (21) extending around an edge of the lid (12) so that the flange (21) extends over or fully covers an edge of the opening (11) providing additional coverage or sealing of the opening (11). Moreover, the openings (11) in relation to the vertical axis (X) are arranged at the same level, where a tip (52) of a blade (51) of the fan (5) is positioned. See Figs. 1 to 6.

[033] In the present embodiment of the UAV (1) the actuator (13) is implemented as an electric motor and linkage mechanism that drives the lid (12). The actuator (13) comprises a lid electric motor (14) with a drive or rotation axis (14A) attached to the body (100) of the unmanned aerial vehicle (1). The actuator (13) also comprises a lever arm (15) connected to an rotation axis (14A) of the lid electric motor (14) and a lid control arm (16) hingedly connected to the lever arm (15) and to the lid (12) so that in a result of a rotation of the rotation axis (14A) of the lid electric motor (14) in one or another direction the lid (12) is brought into respective open position and closed position. The lid (12) itself comprises a hinge (18) that is hingedly connected to the body of the unmanned aerial vehicle (1) via a hinge axis (19) so that the lid (12) is opened or closed by a movement of the hinge (18) around said hinge axis (19). The hinge axis (19) is associated with the body (100) of the UAV (1). See Figs. 1 to 6.

[034] Fig. 8A and 8B illustrate a principle of attitude control - pitch and roll depending on the direction of a flight. Summarising, in any embodiments of the present disclosure attitude control relies on the phenomena of ducted fan thrust change near sections of the duct where the gap between the tip of the blade (51) of the fan (5) and a duct wall (3) is changed.

[035] Fig. 8A is cross-section view of the UAV (1) illustrating equal or symmetric distribution of a lift when the openings (11) are closed and there is no gap increase between the tip (52) of the blade (51) of the fan (5) and a duct wall (3). There is equal thrust (T) in the lower end (2B) of the duct (2). Lift distribution (LD) along the fan (5) blade (51) passing by the closed lids (12) remains similar to other sectors of the duct (2), or the lift distribution (LD) remains similar at all closed lids (12). Consequently, the resultant lift vector (RL) remains unshifted and is aligned with the centre of mass or centre of gravity (CG) of the UAV.

[036] Fig. 8B is cross-section view of the UAV (1) illustrating unequal or asymmetric distribution of a lift when the opening (11) on one side is open or not covered by a lid (12), and enlarged or increased gap is formed between the tip (52) of the blade (51) of the fan (5) and a duct wall (3). Fig. 8B illustrates a condition when in response to signals from the flight control (30), one actuator (13) changes the position of its associated lid (12) relative to the duct (2) opening the opening (11) and increasing the gap between the tip (52) of the blade (51) of the fan (5) and the duct wall (3) which is in the form of the lid (12). As a result, lift distribution (LD) is changed at that opening (11) due to increased tip losses near the tip (52). Thus, the lift distribution (LD) from the blade (51) passing an opened opening (11) is distorted resulting in reduced resultant thrust (T), whereas lift distribution (LD) from the blade (51) passing a closed opening (11) is undistorted resulting in unchanged resultant thrust (T), which is greater than resultant thrust (T) of a blade (51) passing an opened opening (11). This imbalance shifts the resultant lift vector (RL) towards the fan blade passing the closed opening (11) and away from the centre of mass (CG) by such a distance (D) that momentum (M) occurs which tilts the UAV (1), thus ensuring the attitude authority. Depending on which UAV (1) axis an opened opening (11) or lid (12) is located, said tilting is in the form of pitching or rolling.

[037] Fig. 9 and 10 illustrate another embodiment of the UAV (1) comprising all the members of the embodiment of the UAV (1) as disclosed in Figs. 1 to 8B, except this embodiment of the UAV (1) comprises three fan blades (51) and three equally distributed variable gap duct units (10). In addition Fig. 10 illustrates a cross-sectioned duct wall (3) for more clearly visualisation of flanges (12A) of the lids (12) that further covers and seals the opening (11) in the duct wall (3).

[038] Fig. 11 and 12 illustrate yet another embodiment of the UAV (1) comprising all the members of the embodiment of the UAV (1) as disclosed in Figs. 1 to 8B, except it comprises two counter rotating fans (5) where each fan (5) is operatively coupled to its respective electric motor (4). Both fans (5) are arranged so that the tips (52) of the blades (51) of both fans (5) are at the same level as the openings (11) or lids (12) in the duct wall (3).

[039] Fig. 13 illustrates another embodiment of an UAV (1) in a bi-copter configuration. The UAV (1) comprises a body (100) that defines two ducts (2). Each duct (2) is enclosed by a duct wall (3). Each duct (2) comprises one fan (5) and two variable gap duct units (10). The control of the bi-copter is provided in the following manner: pitch of the bi-copter is controlled by opening two of the lids (12) on either front or rear duct (2); and roll is controlled by providing higher thrust to one of two fans (5).

[040] While the invention may be susceptible to various modifications and alternative forms, specific embodiments of which have been shown by way of example in the figures and have been described in detail herein, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention includes all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the following claims.

Claims

CLAIMS An unmanned aerial vehicle (1), comprising: a body that defines a duct (2) enclosed by a duct wall (3) with an upper end (2A) and a lower end (2B) that is opposite to the upper end (2A), a vertical axis (X) extending through a centre of the duct (2) and from the upper end (2A) to the lower end (2B); at least one fan electric motor (4); at least one fan (5) positioned within the duct (2) and operatively coupled to the at least one electric motor (4) for rotating the at least one fan (5) and generating an airflow into the upper end (2A) of the duct (2) and out of the lower end (2B) of the duct (2) in result of which a thrust (T) is generated; characterized in that the unmanned aerial vehicle (1) comprises at least two variable gap duct units (10), wherein each variable gap duct unit (10) comprises:

- an opening (11) in the duct wall (3),

- a lid (12) covering the opening (11) and configured to be movable from a closed position, wherein the lid (12) closes the opening (11), to an open position, wherein the lid (12) is retracted from the opening (11),

- an actuator (13) operatively connected to the lid (12) and configured to drive the lid (12) from the closed position to the open position and back; and wherein the opening (11) in relation to the vertical axis (X) is arranged at the same level, where a tip (52) of a blade (51) of the fan (5) is positioned. The unmanned aerial vehicle (1) according to claim 1, characterised in that the vehicle comprises two fans (5) and two electric motors (4), wherein each fan (5) is operatively coupled to each respective electric motor (4), wherein the fans (5) are contra rotating fans (5) and both fans (5) are arranged so that the tips (52) of the blades (51) of both fans (5) are at the same level as the openings (11) in the duct wall (3). The unmanned aerial vehicle (1) according to claim 1 or 2, characterised in that the actuator (13) comprises:

- a lid electric motor (14) attached to the body of the unmanned aerial vehicle (1);

- a lever arm (15) connected to an rotation axis (14A) of the lid electric motor (14); - a lid control arm (16) hingedly connected to the lever arm (15) and to the lid (12) so that in a result of a rotation of the rotation axis (14A) of the lid electric motor (14) in one or another direction the lid (12) is brought into the open position and closed position. The unmanned aerial vehicle (1) according to any of claims 1 to 3, characterised in that the lid (12) comprises a hinge (18) that is hingedly connected to the body of the unmanned aerial vehicle (1) via a hinge axis (19) so that the lid (12) is opened or closed by a movement of the hinge (18) around said hinge axis (19). The unmanned aerial vehicle (1) according to any of claims 1 to 4, characterised in that the lid (12) comprises a flange (21) extending around an edge of the lid (12) so that the flange (21) extends over an edge of the opening (11) providing additional coverage of the opening (11) by the lid (12). The unmanned aerial vehicle (1) according to any of claims 1 to 4, characterised in that it comprises a flight controller (30) attached to the body of the unmanned aerial vehicle

(I), wherein the flight controller (30) is electronically connected to the fan electric motor (4) and to the actuator (13) and wherein the flight controller (30) is configured to control the fan electric motor (4) for generating the necessary thrust (T) for a the unmanned aerial vehicle (1) and to control the actuator (13) to open or close the lid (12) for providing necessary roll and pitch of the unmanned aerial vehicle (1). The unmanned aerial vehicle (1) according to any of claims 1 to 5, characterised in that vehicle (1) comprises two ducts (2) arranged in a bi-copter configuration. The method for controlling a pitch and roll authority on an unmanned aerial vehicle (1) according to any of claims 1 to 7, wherein the pitch or roll is controlled by opening the lid (12) that covers the opening (11) in the duct wall (3) on that side of the duct wall (3), on which a pitch or roll movement is necessary, as the opening of the respective opening

(I I) decreases a lift on that respective side of the opening (11) and the unmanned aerial vehicle (1) rolls or pitches on that respective side. The method according to Claim 8, wherein a resultant pitch and roll is controlled by opening at least two adjacent lids (12) that cover the openings (11) in the duct wall (3) on that side of the duct wall (3), on which a resultant pitch and roll movement is necessary, as the opening of the respective adjacent openings (11) decreases a lift on that respective side of both openings (11) and the unmanned aerial vehicle (1) rolls and pitches on that respective side.