SE2350775A1

SE2350775A1 - Multi-rotor aerial vehicle

Info

Publication number: SE2350775A1
Application number: SE2350775A
Authority: SE
Inventors: Anders Ljung
Original assignee: Acc Innovation Ab
Priority date: 2023-06-22
Filing date: 2023-06-22
Publication date: 2024-12-23
Also published as: WO2024263092A1

Abstract

Unmanned hydraulic multirotor aerial vehicle (1), comprising a hydraulic pump (14) for powering the at least two rotors (2,3) of the vehicle (1), wherein at least one of the rotors (3) comprises control for collective (26) pitch, optionally also cyclic pitch (27).

Description

MULTI-ROTOR AERIAL VEHICLE The present application is related to a multirotor aerial vehicle according to the claims.

BACKGROUND Hydraulic driven aerial vehicles have been known for quite some time. One such document disclosing such a vehicle is document WO2016068784A1 (ACC). But also more resent documents have been published such as EP3450312A1, disclosing a quadrocopter configuration with all pumps on a common axle in line with document WO2016068784A1. None of the above documents have come into mass production. Only single prototypes exist until this day.

SHORT DESCRIPTION OF THE INVENTION lt has been found that handling an hydraulic aerial vehicle on the ground is difficult. Also controlling a multirotor hydraulic aerial vehicle with hydraulic power, is a challenge. ln order to remedy this challenge it has been suggested an hydraulic multirotor aerial vehicle according comprising, at least two rotors. The vehicle further comprises at least two hydraulic motors, and at least two coupling lines to the hydraulic motors. The vehicle also comprises at least one hydraulic pump. Preferably, the hydraulic pump is arranged with variable displacement volumes. The hydraulic pump is connected to the hydraulic motors with the hydraulic coupling lines, for powering the motors. The vehicle further optionally comprises at least two rotor beam devices on which the respective rotors and motors are optionally mounted. At least one of the rotors comprises collective pitch control, and preferably also cyclic pitch control, the optional cyclic pitch control comprising a swashplate, wherein the hydraulic pump comprises at least two section pumps coupled to the respective rotor. The vehicle further comprises a control unit which is arranged to control the hydraulic aerial vehicle by controlling at least controlling the collective pitch of the at least one rotor.

The advantage being that the control of the aerial vehicle is very improved. The control of the vehicle is very much improved, in particular with a hydraulic powered aerial vehicle of a bigger size, where the traditional way of control is only using control of rotation speed of individual rotors for control in flight. ln a further development there is disclosed a hydraulic aerial vehicle according to claim 2.

By arranging a fold section the vehicle may be put in a compact state for transport. lt is particularly advantageous that the main body may be folded as this may make the vehicle compact in a way that is in general not usual for aerial vehicles. Thy hydraulic power system provides for making folding easy. ln a further development there is disclosed a hydraulic aerial vehicle according to claim 3.

By having fold sections on also beam devices, it is possible to make the vehicle extra compact for transport. ln a further development there is disclosed a hydraulic aeria| vehicle according to claim 4. This is a simple way of controlling the lift force provided by a rotor. ln a further development there is disclosed a hydraulic aeria| vehicle according to claim 5. Control valves add a very good control possibility for a particular rotor. ln a further development there is disclosed a hydraulic aeria| vehicle according to claim 6.

With several rotors having collective pitch, we have a very good possibility to control the lift force of a particular rotor. Adding or switching to cyclic pitch gives even more control. By having more than one rotor having collective pitch, optionally also cyclic pitch, the hydraulic aeria| vehicle gets an extremely good manoeuvrability and less sensitivity to disturbing forces from wind etc. ln a further development there is disclosed a hydraulic aeria| vehicle according to claim 7.

By applying a more controllable pump than a simple hydraulic pump, there is possibility to add much more control to flow and pressure to the motors for the vehicle. This will add control in a way that may be used for redundancy, by way of example, if a collective pitch or a control valve is no longer operational, or together with these control configurations, for increasing or decreasing lift of an individual rotor. ln a further development there is disclosed a hydraulic aeria| vehicle according to claim 8.

A simple pump solution makes it possible to simplify the vehicle and also make it more robust. ln a further development there is disclosed a hydraulic aeria| vehicle according to claim 9.

The preferred configuration is a four rotor configuration. This gives very good control, also redundancy is improved. Three rotors or even two rotors may keep the vehicle flying if something happens to the further rotors etc. The vehicle may have more rotors also, for example eight rotors with rotor pairs on the same rotor axis. ln a further development there is disclosed a hydraulic aeria| vehicle according to claim 10. lf all rotors have collective pitch, optionally also cyclic pitch control, the hydraulic aeria| vehicle may be controlled very efficiently and easily. Also very advance flying configurations may be achieves, such as inverted flying etc. The combination of hydraulic power and collective pitch, optionally also cyclic pitch, may give hitherto unknown possibility to control the vehicle. ln a further development there is disclosed a hydraulic aerial vehicle according to claim 11.

The advantage of using one or several rudders is that the rotors don't need to have extensive overpower in order to provide for yaw movement. Also, the inertia of the rotors can be reduced, and the control of the vehicle is greatly improved. ln a further development there is disclosed a hydraulic aerial vehicle according to claim 12.

The advantage of extending on a line parallel with the radius of the respective rotor, is the simplicity of control and the effectiveness of control. And also by not extending the rudder along the full radius, a lighter but still efficient control is achieved by the rudder. ln a further development there is disclosed a hydraulic aerial vehicle according to claim 13.

The rotating shaft solution is very elegant, and provides excellent control of the rudder, and in turn the vehicle. ln a further development there is disclosed a hydraulic aerial vehicle according to claim 14. With a fixed wing the power consumption may be considerably reduced in transition flying. ln a further development there is disclosed a hydraulic aerial vehicle according to claim 15.

With a push and/or pull propeller the aerial vehicle may be made faster and a particular propeller different from the rotors may be optimised for powering the vehicle with less power than the rotors.

LIST OF DRAWINGS Fig. 1 Discloses a first hydraulic aerial vehicle according to the disclosure. Fig. 2 Discloses a second hydraulic aerial vehicle according to the disclosure. Fig. 3 Discloses the hydraulic aerial vehicle of Fig. 2 in a folded state.

Fig. 4 Discloses a hydraulic pump according to the disclosure.

Fig. 5 Discloses a hydraulic aerial vehicle according to the disclosure.

Fig. 6 Discloses a hydraulic aerial vehicle according to the disclosure.

DETAILED DESCRIPTION The present disclosure is related to an aerial vehicle 1. The disclosure is in particular related to a hydraulic aerial vehicle. This means that the powering of the vehicle 1 is made through a hydraulic system of the vehicle, that provides for power to lift off and move in the air. The vehicle is unmanned. This means that there is not a pilot on board. However, this should not be construed to meant that the vehicle 1 is small, in particular the vehicle is able to lift any load of any weight. The hydraulic powering of the vehicle 1 is very optimized for lifting large loads. The vehicle can have many uses, for example rescue, lifting for construction, such as wind mills, operating as a sky crane, firefighting, etc. The vehicle is intended for unmanned operation. Even if person could be lifted and be transported by the vehicle 1. Thus the vehicle is preferred to be an Unmanned hydraulic aerial vehicle.

Fig. 1 discloses a first variant of the hydraulic aerial vehicle 1. The vehicle has at least two rotors 2, 3. ln Fig. 1, the rotors are drawn in perspective, this is only for disclosing the details better. Fig. 1 should not be construed as the rotors 2, 3, 4, 5 are pointing up in the figure, that is in the plane of the "paper". Thus, in Fig. 1 it should be construed that the rotors 2, 3, 4, 5 are pointing up from the "paper". This definition is also true for Fig. 2, 3, and 5. The line 40 also found in Fig. 2, 3, 5, 6, is just a peripheral line disclosing the outer perimeter of the rotor disc, when the respective rotor is rotating.

The configuration of Fig. 1, is a four rotor configuration, i.e. a quadrocopter configuration. The rotors 2, 3, 4, 5, are all powered by hydraulic fluid that runs to a comprised respective hydraulic line 10, 11, 12, 13. A hydraulic pump 14, Fig. 4, provides the pressurized fluid. The hydraulic lines 10, 11, 12, 13 run all to a respective hydraulic motor 6, 7, 8, 9. A control unit 32 is provided in the vehicle 1, to control the hydraulic aerial vehicle 1. At least one of the rotors 3 is provided with a collective pitch 26. There may also be cyclic pitch 27. lf there is applied cyclic pitch, the control system comprises a swashplate 33. lt should be said that other numbers of rotors are possible, for example an eight rotor configuration with four rotor pairs, provides for a redundant configuration. With an eight rotor configuration it is preferred that each rotor pair is counter rotating. But also five, six, nine, ten and further rotors are possible. Each rotor should be controllable, either by collective pitch, collective and cyclic pitch, and/or variable rotational speed, according to what is described in this disclosure. Fig. 1 discloses a four rotor configuration. Fig. 2 discloses a three rotor configuration. Fig. 5 discloses a two rotor configuration.

There is a hydraulic pump 14, comprising section pumps 14a. Each section pump 14a, 14b, 14c, 14d, is dedicated to provide hydraulic fluid to a respective hydraulic motor 6, 7, 8, 9.

The hydraulic motors 6, 7, 8, 9, may be a gear motor. The hydraulic motors 6, 7, 8, 9, may also be of the type bent axis hydraulic motor, i.e. a fixed displacement motor. But, other type of hydraulic motors is thinkable, a Vane motor, Gerotor motor, Axial plunger motors, or a Radial piston motor, inward or outward pushing pistons.

The rotors 2, 3, 4, 5 of all disclosed hydraulic aerial vehicles 1 in this disclosure may be of two types. One type is a fixed rotor 2 and 5 in Fig. 1, which cannot alter any angle or the like of a rotor blade in flight. lt may still have a pitch that can be changed, but not in a manner that allows for control of the vehicle 1. The control of the rotor and the lift force from it is made by altering the rotation speed of the rotor. The second type of rotor is a rotor which has collective pitch 26. This is in general how the tail rotor of a helicopter is controlled. Also, the main rotor of an helicopter has collective pitch, but most often combined with cyclic pitch. The rotor blades may alter the angle, through the collective pitch 26, such that more or less lift is given from the rotor disc of the rotor 3 at a constant rotation speed. ln general the collective pitch 26 allows for very quick control of the lift force, which improves the manoeuvrability considerably over the fixed rotor type with varying speed of rotation for control. Using collective pitch 26 on all rotors 2, 4, 5, 6, gives a very good concept for a hydraulically powered quadrocopter, or multirotor aerial vehicle, with even more rotors.

The rotors 2, 3, 4, 5 are arranged to rotate in in a direction such that the torque on the vehicle is cancelled from the rotation of the rotors. For example in Fig. 1 the rotors 2 and 5 may rotate clockwise and the rotors 3 and 4 may rotate counterclockwise. lt is also thinkable to include cyclic pitch 27 which then will require a swashplate 33. Having cyclic pitch makes it even more possible to alter the direction of lift of a rotor 3 that has this configuration.

There is possible to vary the lift for directional adjustments.

The hydraulic coupling lines 10, 11, 12, 13 may have control valves 28, 29, 30, 31. The valves may or may not be used for controlling the flow of fluid to the respective rotors. lt is not fully shown in Fig.1, 2, 3, 5, that the hydraulic lines 10, 11, 12, 13 are loops. |.e. the lines run from the pump 14 to the respective hydraulic motor and back to the pump 14. lt should also be said that the valves 28, 29, 30, 31, may be positioned either on the inlet side to a respective hydraulic motor, or on the outlet side, or the valves are comprised within the pump 14 at or in each section pump. The valves may be used for controlling the fluid arriving at the respective motor, either for fully controlling the flow, or for adding control of a flow from the pump which may be controlled individually by the pump 14.

The hydraulic pump 14 has, as said, section pumps 14a, 14b, 14c, 14d. The section pumps being designated to provide fluid pressure to a respective hydraulic motor. One or several or all of the section pumps may have a plurality of working chambers of cyclically changing volume. The working chambers is controlled by control valves, such that the at least one section pump 14a is controlled to deliver a predetermined variation of hydraulic flow at each moment. Thus, the control of for example rotor 2, Fig. 1, may be achieved by changing the displacement volume in one of the section pumps 14a etc. lt should be understood that this control arrangement means the same as the discussion above on control valves 28, 29, 30, 31. The control of the displacement volume may be made by the central control unit 32. But, there may be a dedicated control unit 34, Fig. 4, for controlling the variable displacement volume. lt should be understood that the section pumps 14a, 14b, 14c, 14d may be controlled individually. Thus, there may be so that one pump 14b only delivers a constant pressure/flow to a respective motor 7, and at the same time another section pump 14a, delivers a variable flow to a respective motor 6. ln such a configuration the control of a first rotor 2 may be made through the variable displacement volume of the first section pump 14a, and the control of the second rotor 3 may be made by the collective pitch 26, and/or the collective pitch 26 in cooperation with a cyclic pitch 27, a third rotor 4 may also be controlled in this way. The fourth rotor 5 may be controlled by the respective section pump 14d, delivering a constant flow/pressure of hydraulic fluid but the control valve 31 is operated to alter the rotation of the rotor 5, by the motor 9. Also it is thinkable that for example for the first rotor 2, the section pump 14a is controlled and delivering a varying displacement volume, i.e. pressure/flow, and together with this a control valve 28 is also controlled. This cooperation giving even higher possibility of control for this rotor 2. This implementation may be possible for any rotor, also the at least one rotor having collective pitch control 26 or both collective pitch 26 and cyclic pitch control 27. Thus, the system built provide for a very flexible control of the vehicle 1.

The section pumps 14a, 14b, 14c, 14d may be arranged on a common axle 28 that powers all the section pumps with the same rotation speed.

The pump 14 is powered by a power unit 35. The power unit 35 may be an electric motor, powered by for example a battery source. The electric motor may also be powered by a ground line, to which the vehicle 1 is connected. The power unit 35 may also be a combustion engine for example using petrol the power unit 35 may also be a gas turbine, running on for example jet fuel or the like.

The hydraulic multirotor aerial vehicle 1 may have folding sections 15, 16, 17, 18, 19. ln particular the main body 24 may have a folding section 15. The folding sections may be arranged as a mechanical lockable arrangement which snaps in place. lt may have a soft stretchable material bellows. The material may be synthetic mesh or even a rubber arrangement. ln particular a rubber bellows on a mechanical hinge may be arranged for preventing water to enter the vehicle. There may be one or more folding sections, in particular if applied beams devices 20, 21, 22, 23 are comprised each beam may have a respective folding section 16, 17, 18, 19. Thus, the vehicle 1 may be made very compact for transport as the folding sections are used to fold the vehicle 1, see the folded version of the vehicle 1a from Fig. 2, in Fig. 3.

The beam devices 20, 21, 22, 23, may be applied for moving the rotors 2, 3, 4, 5 away from each other, such that the rotors do not disturb each other. Also a rotor being longer from a centre of the vehicle 1, may use the leverage for better control of the vehicle. lt should be understood that if a more compact vehicle 1 is desired, the rotors may be positioned at different heights with regard to each other such that the rotors may not intersect.

The vehicle may have two or more rotors 3, 4 with collective pitch 26 optionally in cooperation with collective pitch 27, Fig. 5. The position if a combination of fixed pitch rotors 2, 5 and collective and optionally cyclic pitch rotors 3, 4 us that the latter group should be equal to or longer away from one of these rotor to the closest fixed pitch rotor. Thus, one could say that the predetermined distance should be the longest possible between two rotors having collective pitch 26 or both collective pitch 26 and cyclic pitch 27.

The control unit 32 is thus arranged to control the collective pitch 26 of at least one rotor 3, or preferably all rotors that are equipped with collective pitch 26. The control unit 32 may also control the pump motor 35 of the pump 14. The control unit 32 may also control valves 28, 29, 30, 31, that controls the flow in hydraulic coupling lines. The control unit 32 may thus control, servos for controlling the collective pitch 26 control. The control unit 32 may also control servos for controlling an optional cyclic 27 pitch control.

The hydraulic multirotor aerial vehicle 1a of Fig. 2 has three rotors, in the figure there are two rotors 2 and 4 that have fixed pitch. The vehicle 1a is otherwise similar to the vehicle in Fig. 1. The preferred option may be to not have a fixed pitch rotor, but instead apply collective pitch 26 to all rotors, Fig. 6.

Optionally one might consider cyclic pitch 27 to one or all rotors with collective pitch.

The hydraulic multirotor aerial vehicle 1b of Fig. 5, has only two rotors 3a, 4a. These two rotors have preferably both collective 26 and cyclic pitch 27 for best control of the vehicle 1b. This, gives best control of the vehicle 1b. lt is also thinkable to have one rotor with fixed pitch and one rotor with collective 26 and cyclic pitch 27. The fixed pitch rotor is then controlled by changing rotation speed. lt should be said, that all rotors of any configuration may have collective pitch and optionally cyclic pitch, for control of the respective aerial vehicle 1, 1a, 1b, 1c etc., see Fig. 6. Thus, there may be so that there are no rotors with fixed pitch on the aerial vehicle 1. lt should also be understood that there are no difference intended between the described variants 1, 1a, 1b 1c of the multi rotor aerial vehicles.

The control of any disclosed aerial vehicle may also be made through a remote control device, thus any of the vehicles 1, 1a, 1b, 1c may be controlled from the ground by an operator. lt should also be understood that the hydraulic multirotor aerial vehicle l, la, lb, lc, may be controlled by the control unit 32, and thus flying a predetermined flight pattern.

The aerial vehicles l, la, lb, lc may also comprise navigation capacity, in the form of GPS, Glonass, Galileo or the like capability.

Fig. 3 discloses a folded aerial vehicle according to Fig. 2. The compactness is easily seen from the figure itself. The hydraulic powering system provides for a simple arrangement to fold the vehicles.

Fig. 6 discloses a variant of the hydraulic aerial vehicle lc, with a rudder configuration. lt should be understood that there may be one, two, three or four rudders, depending on the need for control. |.e. one rudder for each rotor, i.e. more than four rudders if there are more than four rotors. However, if there are coaxially positioned rotors, for example counter rotating rotors, one rudder for each pair of rotors may also be a good solution. The most preferred configuration of the vehicle of Fig. 6 is one rudder per rotor. The rudders 4l, 42, 43, 44 are basically a plate, made in a sturdy material, such as carbon fibre, aluminium, titanium or the like. The rudders 4l, 42, 43, 44, are attached to a respective shaft 37, 38, 39, 40, which may rotate individually. The turning or rotation of the rudder a certain angle will divert the air flow from a respective rotor. Thus, the control of the vehicle is improved. The rudders is optionally extending in radius direction of the rotor, but below the rotor. The extension may be the full length of half of the rotor, i.e. the length of a rotor blade. However, it is preferred to have an extension that is not reaching the rotation center of the rotor, and not either the full length of the rotor to the wing tip. This, provides for the best control with the minimum of weight. lt should be said that the size and angle of the rotors in Fig. 6 are just arbitrary. The rotors may have bigger size as will. lt should be said that by using a rudder the rotors 4l, 42, 43, and, 44, may be made smaller and with less mass, as compared to an aerial vehicle not, using rudders, in particular when controlling yaw of the vehicle lc.

The hydraulic aerial vehicle may also have a fixed wing setup, with two main wings and possibly a tailplane with an elevator, and fin with a rudder. There may also be ailerons on the wings. There may also be a pusher or a pull propeller for driving the hydraulic aerial vehicle in airplane mode. This is in particular advantageous as you may extend the range of the vehicle considerably.

Claims

1. Hydraulic multirotor aerial vehicle (1) comprising, at least two rotors (2, 3), at least two hydraulic motors (6, 7), at least two hydraulic coupling lines (10, 11), at least one hydraulic pump (14), preferably the hydraulic pump (14) is a pump arranged with variable displacement volumes, optionally the hydraulic pump (14) comprises a respective section pump (14a; 14b) providing flow to a respective hydraulic motor (6, 7). wherein the hydraulic pump (14) is connected to the hydraulic motors (6, 7), with the hydraulic coupling lines (10, 11), for powering the motors (2, 3) connected to the respective rotor (2,3), and optionally at least two rotor beam devices (20, 21) on which the respective rotors (2, 3) and motors (6, 7) are optionally mounted, characterized in that at least one of the rotors (3) comprises collective pitch (26) control, and preferably cyclic pitch (27) control, the optional cyclic pitch (27) control comprising a swashplate (33), wherein further comprised is a control unit (32; 34) which is arranged to control the hydraulic aerial vehicle (1), by at least controlling the collective pitch (26) of the at least one rotor (3).

2. Multirotor aerial vehicle according (1) to claim 1, wherein the vehicle (1) comprises at least one fold section (15) on the main body (24) of the hydraulic multirotor aerial vehicle (1).

3. Multirotor aerial vehicle according to any of the claims above, wherein the vehicle (1) comprises at least one fold section (16) on one of the at least two beam devices (20, 21).

4. Multirotor aerial vehicle according to any of the claims above, wherein the control of the vehicle (1) is achieved, at least partly, by controlling the speed of at least one the rotor (2), wherein the speed is achieved by control of the flow of hydraulic fluid to the at least one rotor (2), by a control unit (32; 34).

5. Multirotor aerial vehicle (1) according to claim 4, wherein the control of the vehicle (1) at least partly, is achieved by having a constant volume of hydraulic fluid being provided to at least one of the rotors (3) through the hydraulic line (10) that provides the motor (6) of the at least one rotor (2) with hydraulic fluid, and further a control valve (28) is controlling the final volume hydraulic fluid delivered to or exiting from the motor (6).

6. Multirotor aerial vehicle (1) according to any of the claims above wherein at least two of the rotors (3, 4) have collective and optionally cyclic pitch (26, 27), preferably the at least two rotors (3, 4) with collective and optionally cyclic pitch (26, 27), have a predetermined position relationship such that the distance between the two rotors (3, 4) is equal to or/longer than the distance between one of the rotors (3, 4) and a further comprised rotor (5) on the multirotor aerial vehicle (1).

7. Multirotor aerial vehicle (1) according to any of the claims above, wherein at least one section pump (14a) dedicated to the at least one motor (6) associated with a predetermined rotor (2), comprises a plurality of working chambers of cyclically changing volume, wherein the working chambers is controlled by control valves, such that the at least one section pump (14a) is controlled to deliver a predetermined variation of hydraulic flow at each moment, for wherein the control of at least one rotor (2) is achieved by changing the displacement volume in one of the section pumps (14a) in the hydraulic pump (14), and this section pump (14a) is coupled to the hydraulic line (10) that is coupled to the motor (6) of the at least one rotor (2), preferably more than one section pump is of the same type, even more preferred all section pumps (14a, 14b, 14c, 14d) are of the same type.

8. Multirotor aerial vehicle (1) according to any of the claims above, wherein at least one or all of the hydraulic section pumps (14a, 14b) are essentially an hydraulic pump or a variable displacement pump controlled to deliver a constant flow of hydraulic fluid in a respective hydraulic line (10, 11).

9. Multirotor aerial vehicle (1) according to any of the claims above, wherein the vehicle (1) comprises at least four rotors (2, 3, 4, 5), four motors (6, 7, 8, 9), and four hydraulic lines (10, 11, 12, 13), and four hydraulic section pumps (14a, 14b, 14c, 14d), each hydraulic motor, hydraulic line and section pump being arranged to dedicated a dedicated rotor.

10. Multirotor aerial vehicle (1) according to any of the claims above wherein all rotors of the vehicle (1) comprises collective (26) and optionally collective pitch (27) control.

11. Multirotor aerial vehicle (1) according to any of the claims above , wherein at least one, preferably all, rotors (2, 3, 4, 5) comprises a rudder (41, 42, 43, 44), which rudder (41, 42, 43, 44) is arranged using the air flow below a respective rotor (2,3,4, 5) to give the vehicle (1) control in at least VaW.

12. Multirotor aerial vehicle (1), according to claim 11, wherein the rudder (41, 42, 43, 44) is positioned along a radius of a respective rotor, preferably the rudder is extending with apredetermined distance in radius direction from the centre of the rotor (2, 3, 4, 5) and a predetermined distance in radius direction from the outer limit of the rotor.

13. Multirotor aeria| vehicle (1) according to claim 11 or 12, wherein the rudder (41, 42, 43, 44) is attached to a respective shaft (37, 38, 39, 40), wherein the shaft may rotate individually for controlling the rudders angle to the airflow from the respective rotor (2, 3, 4, 5).

14. Multirotor aeria| vehicle (1) according to any of the claims above, wherein the vehicle also comprises a fixed wing, for giving lift in forward flight.

15. Multirotor aeria| vehicle (1) of claim 14, wherein the vehicle (1) further comprises a push and/or pull propeller, that provides power for forward flight.