Field

The present invention relates to improvements to drones and to an improved drone deployment system.

Background

A drone is another name for an unmanned aerial vehicle (UAV). A drone or a UAV is an aircraft without a human pilot on board and is therefore a specific type of unmanned vehicle.

UAVs are also referred to as unmanned aircraft systems (UAS) which may include a UAV, a ground-based controller and a system of communications between the two.

Drones (UAVs) may operate with various degrees of autonomy: either under remote control by a human operator or autonomously by onboard computers and control systems.

Drones have a number of uses in defence, security, communication and surveillance applications.

There is a trade-off between payload and flight time, and this is especially the case where a drone is powered by batteries or rechargeable cells.

There is a particular type of drone, which is referred to as a tethered drone, which is a drone that is tethered and receives an electric current to power on board motors that operate propellers, to power electronic guidance and control systems and to power communication equipment. Such tethered drones are retained in a limited and relatively restricted airspace which is defined by the maximum length of the tether.

Recently, following the advent of tethered drones, the problem of maximum flight time is overcome. Tethered drones by their nature have a limited range however they have the advantage of being able to stay aloft for extended periods.

Despite their theoretically limitless flight time there is a need to transmit electric current at a high voltage, otherwise tethered drones become less efficient due to resistive losses, which are proportional to the square of the electric current (I ² ). Consequently tethered drones have required on-board transformers in order to ‘step down’ voltage and increase the level of supply voltage to on-board components and motors that drive the propellers, and this has added to their payload requirements.

Because tethered drones can be kept aloft for prolonged periods, which are significantly longer in duration than untethered or ‘free flying’ drones, there is a greater need to protect internal components from the elements, in particular rain and ice as prolonged exposure to water is likely to lead to problems with the on-board transformers and other electronic components which operate and control the drone.

There is therefore a greater need to protect these electronic components from exposure to rain due to the fact that they are more likely to encounter rain during a prolonged flight especially in marine or wet climates. This has been achieved by surrounding the components with a lightweight cover in order to protect them.

Even where transformers are efficient, they are prone to overheating. This in turn has led to losses, inefficiency and a greater risk of component failure and a catastrophic failure of the drone. The fact that the electronic components, and especially the transformers are now enclosed in a closed cover, has exacerbated the problem of overheating.

Prior Art

US 2017/0001721 (GoPro Inc) discloses an aerial vehicle. The aerial vehicle may include a removable battery. Various embodiments of removable battery assemblies are described. These include a pull-bar battery assembly, a latch battery assembly, and a lever battery assembly. The aerial vehicle may also include a propeller locking mechanism to which propellers may be removable coupled.

The propeller locking mechanism removes the need for tools for coupling or decoupling propellers to the aerial vehicle.

WO 2016/192021 (SZ DJI Technology Co Ltd) describes a system that is used for transformation of a UAV from an extended state to a compacted state. The UAV can be transported in the compacted state. The UAV comprises one or more segmented arms that are folded to reduce stowage space required to ship the UAV. The segmented arms can be sealed to prevent ambient air, dirt, and or water vapour from entering the segmented arm. There are repeated references to the fact that the arm can be configured to permit air to flow through a branch interior space to the propulsion unit to permit cooling of the propulsion unit.

Although the aforementioned drone mention vents in their supporting arms that may provide an air pathway for cooling, there is no explicit description of how this cooling is achieved.

An aim of the invention is to reduce the risk of overheating of drones, in particular tethered drones.

Another objective of the invention is to optimise the amount of power to payload.

A further object of the invention is to optimise cooling of drones, in particular tethered drones, especially in wet weather conditions.

Summary of the Invention

According to a first aspect of the invention there is provided a drone includes: a plurality of hollow struts extending from a drone body, each strut supports a motor for driving a propeller, characterised in that a centrifugal fan with fan elements is located between the propeller and an inlet to a strut, fan elements are driven by the motor so that air is entrained through the inlet, via the hollow strut, and thereby directed over components within the drone body in order to cool the components.

In one embodiment a fan element sweeps air into a hollow strut towards the drone body. In another embodiment a fan element draws air from within a hollow strut away from the drone body. In a yet further embodiment alternate fan elements sweeps air into a first hollow strut towards the drone body and draws air from within an adjacent hollow strut away from the drone body. In this way air is encouraged to circulate through the body by different fan elements.

Preferably therefore fan elements are operable to force air into the inlet towards the drone body.

In another embodiment the fan elements are operable to draw air from the inlet away from the drone body.

Optionally the fan elements which force air towards or draw air from the inlet are located on alternate struts. An advantage of the invention is that it optimises the amount of payload which is encountered in free flying drones by maintaining the drone body cool, even when the drone body is enclosed against rain and snow. Tethered drones tend to have more electric components that are relatively inefficient compared to free flying drones and therefore more heat is generated during their operation.

Where drones are tethered, extended flight times can be achieved, some more than 24 hours because components can be driven to higher operating regimes, without the need to refuel or recharge and because additional energy can be used to drive the fan elements in order to cool internal components.

Consequently where previously components risked over-heating, as a result of the present invention, components are now continually force cooled thereby improving their efficiency, ensuring continuous operation and reducing the risk of overheating.

Motors previously used to drive propellers are now also used to drive fan elements which when actuated cause air to be entrained through an associated hollow strut in order to cool electrical and electronic components within the drone body.

Ideally the electrical and electronic components are in thermal contact with a heat sink across which the forced air passes. Ideally the heat sink includes fins, slots or apertures which increase the surface area available for cooling.

Ideally centrifugal fan elements draw air via at least one inlet, which is ideally located at an end of the strut closest to the drone body, so that air exhausts from an end of a strut furthest from the drone body. However, the one or more inlets may be located at different locations in the strut and optionally include vanes for directing air at an inlet or an outlet.

Preferably the inlet includes a cowl that is shaped and dimensioned to reduce ingress of rainwater which might enter the strut and so inadvertently increase the weight of the drone or enter the drone body and risk coming into contact with the electrical and electronic components.

Optionally a dust filter is provided to prevent ingress of insects, airborne particulates or dust into the hollow strut.

Optionally the drone body encloses a board on which electrical and electronic components are mounted and at least one fan is provided within the drone body and is operative to force air across the electrical and electronic components and to direct air from the body via at least one port defined in a wall of the drone body. Preferably the at least one fan is mounted on the board which can be operated independently of the fan blades driven by the propeller motors.

In one embodiment at least one port which is defined in a wall of the drone body may be moveable between an open and a closed state and may be actuated to move between the open and closed states by a drive means. The drive means is optionally able to be actuated remotely.

Optionally the drive means is operative when a thermostat, which is ideally located within the body, switches on the drive means to open the port and thereby enables excess heat to be dissipated very quickly. A fan may be provided in the body to speed up heat dissipation.

Ideally at least one port is defined in the base of the drone body and is formed in the base so that when cooling air exhausts from inside the body, the exhaust air does not interfere with the airflow from the propellers, so as not to interfere or reduce downward thrust generated by the propellers that creates lift forces.

In some embodiments the drone has mounted on the board at least one power regulator for modifying the electric voltage from a low voltage to a higher voltage for supply to the motors. In some embodiments, associated with the at least one power regulator is a fan. Optionally the fan may be used to cool two or more regulators and baffles, or guides may be provided to direct air to flow over the or each power regulator or other electronic components.

Preferably the drone includes at least one power regulator which is a transformer. The at least one transformer has a heat sink and the at least one fan is dimensioned and oriented to force air over the heat sink.

In some embodiments the drone has at least one port that is located at an angle with respect to a horizontal, in a base of the drone body. By forcing exhaust air sideways, through the base of the drone body, there is an improvement in cooling as coolant air is forced to regions of air around the body of the drone which is then entrained into the wash of propellers. Ideally components are connected to, and are in thermal contact with, a heat sink over which air is forced. The heat sink preferably includes fins.

Some drones include a tether which tethers the drones to a ground based anchor; the tether also supplies an electric current to components and motors in the drone.

In some embodiments the drone includes an imager and a transmitter for transmitting image data to a remote receiver.

In some embodiments the drone includes audio devices which are configured to receive sounds and a transmitter is provided for transmitting audio data derived from the sounds to a remote receiver.

Optionally the drone includes or has one or more sensors mounted thereon. Sensors may be adapted to receive signals or measure temperature or monitor ambient conditions such as air quality or a particular gas or other airborne chemical or hazard.

Some embodiments of the drone may therefore include a transmitter for transmitting a signal indicative of air quality to a remote receiver. The transmitter may be connected to a remote receiver via a hardwire link in the tether or optionally via a radio frequency (RF) communication channel or even via an optical communication system.

Ideally the drone receives an electric current via a wire which forms the tether and the current powers the components and the at least one fan and the motors.

According to another aspect of the invention there is provided a tethered drone system that includes: the aforementioned drone, a winch which is a powered drum around which the tether is wound, and the drone is powered by a ground based transformer.

The system is ideally mounted on a vehicle. Optionally the drum has apertures formed therein so that air passes through the apertures in order to cool the tether and a cable that transmits electric current to the drone.

The system overcomes resistive heating which occurs as result of resistive losses that can occur in the cable or wire which supplies the electric current.

Brief Description of a Preferred Embodiment of the invention

Embodiments of the invention will now be described, by way of example only and with reference to the Figures, in which: Figure 1 shows an overall view of one example of a drone;

Figure 2 shows an underside view of the drone with electric centrifugal fans (shown in detail in Figure 6) that urge air through the struts and the drone body;

Figure 3A is a part sectional, side elevation view of one of the struts and shows a motor and a propeller and illustrates strut configuration when centrifugal fans are used on an underside of the drone body;

Figure 3B is a part sectional, plan view corresponding to 3A and shows the strut and the motor and a portion of a propeller and illustrates strut configuration when the centrifugal fans are used on an underside of the drone body;

Figure 4 is a part sectional view of an alternative arrangement to the embodiment shown in Figures 3A and 3B and illustrates the cowling around the centrifugal fan blades attached to the motor;

Figure 5 is an overall view of the arrangement shown in Figures 3A and 3B and indicates the position of a centrifugal fan and blades which are used to draw or direct air into the struts;

Figure 6 is a partial, sectional plan view of an interior of the drone shown in Figure 1 and depicts heat sinks across which air flows and exhausts outwards through the struts and through the drone body;

Figure 7 is a part sectional plan view of an interior of the drone shown in Figure 6 and depicts heat sinks and location of fans and illustrates openings on the underside of the drone body when arranged to allows air to be drawn from below the drone, through the inside of the drone body and out via the struts; and

Figure 8 shows a diagrammatic view of a deployment system including the drone shown in Figures 1 to 7 and a drum around which a tether is wound.

Detailed Description of Preferred Embodiments of the Invention

Referring to the Figures generally, there is shown a drone 10 comprising a drone body 12 which is covered by a drone housing or cover 14. Extending from the drone body 12 are six struts 16a to 16f respectively.

Referring now to Figures 2 and 3 there are shown views depicting propellers 17a to 17f mounted on motors 18a to 18f respectively. The struts 16a to 16f are hollow and support motors 18a to 18f respectively. Each motor 18 has associated therewith a centrifugal fan 28a to 28f, with fan blades 49 which are shown in greater detail in Figure 5.

Centrifugal fans 28 are mounted on and driven by each motor 18a to 18f at the end of each strut. However, in some embodiments centrifugal fans 28 may be provided on only some of the motors 18a to 18f but in a manner so as to ensure stability in flight and balanced air flow.

In Figure 5, the fan blades 49 direct air towards an inlet of the strut 16c when rotating in the direction of the arrow shown. When the propeller 17 on an adjacent strut 16 rotates in an opposite sense to the propeller shown in Figure 5, air is drawn from within the strut 16c. Air can be drawn from a strut or directed towards a strut, irrespective of the direction of the propeller rotation or position on the drone. What is important is that fan blades 49 are arranged to ensure a desired direction of air flow, either forced into a strut or drawn from it. As fan blades 49 are reversible a user is able to change or reverse them according to conditions or to alternate the direction air flow, for example in order to flush any particles or dust from within a strut or a filter connected thereto.

Referring again to Figure 3 and Figure 4 the centrifugal fan 28c is driven directly from motor 18c via a motor drive 29c. Propellers 17c are connected to the motor 18c and an interconnect 21 joins their ends one to another. Mounted towards distal ends of each strut 16 are motors 18a to 18f respectively.

Figure 4 shows a detailed view of a support strut 16c and shows an alternative arrangement of locating the motor 18c to the arrangement depicted in Figure 3. The centrifugal fan 28c is shown below the motor 18c and is driven directly from a motor drive (shown in detail in Figure 5). Figure 5 is an enlarged view, corresponding to the view, shown in Figure 3 and Figure 4 and shows the strut 16c supporting the centrifugal fan 28c below the motor 18c. The struts 16a to 16f are generally square in cross section and are hollow in order to reduce weight. In some embodiments the struts 16 may be circular or elliptical in cross section, or a portion of their internal cross section may be so shaped, in order to improve flow of air therethrough.

The struts 16 connect to the housing 14 and define a pathway for the air which cools the components. The struts 16 support the motors 18 and centrifugal fans 28. The position of the centrifugal fan 28 and the fan blades 49 is depicted in greater detail in Figure 5 which also shows the relationship between fan blades 49 and an air inlets that opens into the strut 16 via a blocking fairing 25 shown in Figure 3a. A dust filter 32 is provided at the end of each strut in order to prevent ingress of debris. Ideally these are replaced at regular intervals to avoid build up of debris and so reduce the risk of them clogging thereby ensuring always of optimum airflow through the struts for cooling.

Figure 6 is a part sectional plan view of an interior of the drone 10 shown in Figure 1 and depicts heat sinks 24 below plate or chassis 20 which may be considered is in thermal contact with a main heat sink 24 as shown in Figure 2. The heat sinks 24 extend from an inner region of the drone housing 14, on which components 19 are mounted. The heat sinks 24 extend through the drone housing or cover 14 and project to an exterior of the drone 10. Fleat sink 24 encircles the housing or cover 14, in the form of a hoop or flat disc, with apertures 36 or slots cut therefrom in order to optimise airflow and thereby enhance forced convective cooling as the drone 10 flies through the air.

At least one fan 44, and ideally three separate fans 44, are located inside the housing or cover 14, to force air over the electrical and electronic components 19, in particular the heatsink 24 which is in contact with the regulators 40, in order to force cool them. It is appreciated that the regulators 40 may also have integral fins formed thereon in order to further increase available surface area for forced convective and radiative cooling.

Figure 7 is a part sectional plan view of an interior of the drone shown in Figure 6 and depicts heat sinks and location of fans. Figure 7 shows how cooling is achieved with the configuration shown in Figure 5 when air is forced into the strut 16c. If the direction of rotation of the fan blades 49 is reversed air is drawn out of the strut 16c.

Components 19 are supported on a chassis 20 within the drone housing 14. Air is drawn through chassis openings 42 into the drone housing or cover 14 or expelled through the chassis openings 42, through the interior of the housing 14 and across regulators 40 which are thereby cooled. Heat is also dissipated by way of the heat sink 24 and cooling is enhanced by way of slots or apertures 36 formed in the heat sink 24. Additionally slots or apertures may be formed in the drone housing or cover 14.

Figure 8 shows a diagrammatic view of a deployment system including the drone 10 shown in Figures 1 to 7 and a drum 60 around which tether 50 is wound. The drum is transported on a vehicle 70 and an imaging system 80 is supported on the drone 10. Electric current is supplied to the drone 10 via the tether 50. In one embodiment the drum 60, around which the tether 50 is wound has apertures (not shown) formed therein, through which apertures air passes in order to cool the tether 50.

Variation may be made to the above mentioned embodiments when they are deployed in cold conditions in the form of a different cover which reduces cooling as this may not be required in freezing conditions. Likewise dust filters may be removed and replaced by caps which prevent ingress of moisture which may otherwise freeze and increase the mass of the drone.

The invention has been described by way of exemplary embodiments and variation may be made to them, without departing from the scope of protection, as defined in the appended claims.

Parts List

Drone 10

Drone body 12

Drone housing or cover 14

Struts 16a to 16f

Propellers 17a to 17f

Motors 18a to 18f

Components 19

Chassis 20

Interconnect 21

Heat sink 24

Blocking fairing 25

Centrifugal fans 28

Motor Drive 29

Inlet 30

Dust filter 32

Apertures 36

Regulators 40

Openings 42

Fans 44

Fan blade 49

Tether 50

Drum 60

Vehicle 70

Imager 80