Rotor head for aerial vehicle

A rotor system for aerial vehicles where two or more rotor systems are used in a coaxial or tandem arrangement on the aerial vehicle.

TECHNICAL FIELD

The present disclosure is related to the field of aerial vehicles, in particular, rotor heads for aerial vehicles such as helicopters and unmanned aerial vehicles.

BACKGROUND

Unmanned aerial vehicles (“UAVs”), better known as drones, are one of the technological marvels of our age. They can document the aftermath of disasters without putting additional people at risk, and the corporate sector plan to use them for small package delivery in the not-too-distant future.

Large delivery and service companies have plans for turning drone technology into new sources of revenue. Amazon has announced its “Prime Air,” a delivery system it says will eventually allow the company to “to safely get packages into customers' hands in 30 minutes or less” using small drones. In 2014, DHL Parcel announced the start of regular, autonomous drone flights to a sparsely inhabited German island in the North Sea for scheduled deliveries of medications and “other urgently needed goods” to the local community. Google also has a drone delivery service called Wing in the works. Providing a drone for logistics applications still requires overcoming the problems of being able to carry large payloads over large distances and/or being able to operate for extended periods of time. Drones that can carry small payloads can flown over longer distances than drones carrying larger payloads due to the drain on the batteries required for the additional power needed to lift the larger payloads.

Multi-copiers have largely become ubiquitous within the Unmanned Aerial Vehicle market, however, it is apparent that scaling multi-copter design up to carry higher payloads or increase endurance is prohibitively expensive and complex. As size and, therefore, inertia of the aerial vehicle increases, pitch, roll and yaw control of the aerial vehicle becomes much harder to accomplish by increasing and decreasing the motor speeds. Helicopter-design UAVs, therefore, offer superior performance for large unmanned systems. However, helicopter-design is necessarily more complex than design of multi-copiers.

It is, therefore, desirable to provide a simple, cost-effective rotor head design for incorporation into various helicopters including coaxial, traditional, tandem and synchropter helicopter designs.

SUMMARY

A novel rotor head design for aerial vehicles provided. In some embodiments, the rotor head design can comprise three main novel aspects:

First, in some embodiments, the rotor head can comprise a direct-drive motor, whereas traditional helicopters incorporate either a gear- or belt-drive system. The direct drive motor can comprise fewer moving parts and a more efficient drive-train having no transmission losses, reduced complexity, increased reliability and reduced cost.

Second, in some embodiments, the rotor head can comprise a swashplate synchronisation mechanism incorporated into the pitch driver links via a master-slave relationship. This arrangement can reduce part count and complexity, as well as increasing reliability.

Third, in some embodiments, the design can comprise a single direction cyclic and collective rotor head, which can reduce the cyclic direction to one direction only (pitch or roll). This can reduce the number of actuators required for cyclic and collective control of the swashplate from three to two. This feature can be especially useful when more than one rotor head is present on the aerial vehicle, such as in a coaxial or tandem helicopter. This can also reduce complexity and cost, as well as increasing reliability.

Broadly stated, in some embodiments, a rotor system can be provided for an aerial vehicle, comprising: a motor mount configured for attaching to the aerial vehicle; a motor stator operatively coupled to the motor mount; a motor rotor rotatably disposed within the motor stator; a spine shaft operatively coupled to the motor mount; a rotor hub operatively coupled to the motor rotor; at least two rotor blades rotatably coupled to the rotor hub, the at least two rotor blades disposed in a spaced-apart configuration about a circumference of the rotor hub, the at least two rotor blades operatively coupled to the rotor hub via a blade grip, the blade grip rotatably coupled to a feathering shaft extending from the rotor hub; at least one pitch servo motor disposed near one end of the spine shaft, the at least one pitch servo motor comprising a servo arm; and a swashplate mechanism operatively coupling the at least one pitch servo motor to the blade grip, wherein operation of the swashplate mechanism adjusts a pitch angle of the at least two rotor blades.

Broadly stated, in some embodiments, an aerial vehicle can be provided comprising at least two rotor systems, wherein each of the at least two rotor systems comprises: a motor mount configured for attaching to the aerial vehicle; a motor stator operatively coupled to the motor mount; a motor rotor rotatably disposed within the motor stator; a spine shaft operatively coupled to the motor mount; a rotor hub operatively coupled to the motor rotor; at least two rotor blades rotatably coupled to the rotor hub, the at least two rotor blades disposed in a spaced-apart configuration about a circumference of the rotor hub, the at least two rotor blades operatively coupled to the rotor hub via a blade grip, the blade grip rotatably coupled to a feathering shaft extending from the rotor hub; at least one pitch servo motor disposed near one end of the spine shaft, the at least one pitch servo motor comprising a servo arm; and a swashplate mechanism operatively coupling the at least one pitch servo motor to the blade grip, wherein operation of the swashplate mechanism adjusts a pitch angle of the at least two rotor blades.

Broadly stated, in some embodiments, wherein the swashplate mechanism can further comprise: a swashplate stator circumferentially disposed around the spine shaft; a swash link operatively coupling the servo arm to the swashplate stator; a swashplate rotor rotatably circumferentially disposed around the swashplate stator; and a master pitch link operatively coupling the swashplate rotor to the blade grip of a first rotor blade of the at least two rotor blades.

Broadly stated, in some embodiments, the swashplate mechanism can further comprise a slave pitch link operatively coupling the swashplate rotor to a second rotor blade of the at least two rotor blades.

Broadly stated, in some embodiments, the rotor system can further comprise a control unit configured for controlling the operation of the rotor system.

Broadly stated, in some embodiments, the aerial vehicle can further comprise a control unit configured for controlling the operation of each of the at least two rotor systems.

Broadly stated, in some embodiments, the at least two rotor systems can be configured in a coaxial or tandem arrangement on the aerial vehicle.

Broadly stated, in some embodiments, a method can be provided for manufacturing an aerial vehicle, the method comprising: mounting at least one rotor system on the aerial vehicle, wherein each of the at least one rotor system comprises: a motor mount configured for attaching to the aerial vehicle; a motor stator operatively coupled to the motor mount; a motor rotor rotatably disposed within the motor stator; a spine shaft operatively coupled to the motor mount; a rotor hub circumferentially disposed around the spine shaft; at least two rotor blades rotatably coupled to the rotor hub, the at least two rotor blades disposed in a spaced-apart configuration about a circumference of the rotor hub, the at least two rotor blades operatively coupled to the rotor hub via a blade grip, the blade grip rotatably coupled to a feathering shaft extending from the rotor hub; at least one pitch servo motor disposed near one end of the spine shaft, the at least one pitch servo motor comprising a servo arm; and a swashplate mechanism operatively coupling the at least one pitch servo motor to the blade grip, wherein operation of the swashplate mechanism adjusts a pitch angle of the at least two rotor blades.

Broadly stated, in some embodiments, the method can comprise mounting two of the at least one rotor system in a coaxial arrangement on the aerial vehicle.

Broadly stated, in some embodiments, the method can comprise mounting two of the at least one rotor system in a tandem arrangement on the aerial vehicle.

DETAILED DESCRIPTION OF EMBODIMENTS

It may be useful for understanding of the rotor head to split the components up into “rotors” and “stators”. Stators are fixed rotationally to the aerial vehicle, whereas rotors spin with the same speed as brushless direct current (“DC”) motor100, as shown inFIGS.1to4.

Referring to the Figures, in some embodiments, the elements or features pertaining to “stators” can comprise”:Motor mount (1)Motor stator (2)Spine shaft (5)Servo mount plate (6)Servo motors (15)Servo arms (14)Swash links (12)Swashplate stator (11)

Referring to the Figures, in some embodiments, the elements or features pertaining to “rotors” can comprise”:Motor rotor (3)Rotor hub (4)Feathering shaft (18)Flapping pin (17)Damper (19)Blade grip (20), bearings (21), feathering shaft bolt (22)Rotor blades (7)Swashplate rotor (10)Master pitch link (9)Slave pitch link (8)

Referring toFIGS.1to6, in some embodiments, stator2of brushless DC motor100can be fastened to motor mount1, which can be fixed to airframe of an aerial vehicle (not shown). Spine shaft5can also be fixed to motor mount1. A through-bore in DC motor100can allow spine shaft5to pass through the DC motor100. Servo mount plate6can be fixed to spine shaft5. In some embodiments, rotor3of the brushless DC motor100can connect to rotor hub4. As shown inFIG.3, rotor3can be rotatably disposed on bearings34disposed between stator2and rotor3wherein rotor3can thereby rotate freely within and around stator2as well as rotate around spline shaft5.

In some embodiments, feathering shaft18can be attached to rotor hub4via flapping pin17and can pivot about the axis of flapping pin17. In some embodiments, flapping damper19can dampen the flapping movement of feathering shaft18about flapping pin17.

In some embodiments, blade grip20can be mounted to feathering shaft17with bearing stack21and fastened in place with feathering shaft bolt22. This can allow rotational movement of blade grip20about the axis of feathering shaft18but not translational axial movement. In some embodiments, each blade7can be bolted to blade grip20.

In some embodiments, two servomotors15can be mounted to servo mount plate6and can provide electromechanical rotation to servo arms14about the output shafts of servomotors15. In some embodiments, swashplate stator11can be attached to each servo arm14via one swash link12each.

In some embodiments, swashplate stator11can be mounted to spine shaft5using ball joint16, the inner race of which can slide freely along spine shaft5. Swashplate stator11can, therefore, translate along the axis of spine shaft5and rotate about the point of rotation of ball joint16. In some embodiments, servo arms14and swash links12can further constrain the rotation of swashplate stator11to an axis parallel to the output axis of servomotor15. By axial movement of the swashplate11, collective pitch can be imparted to rotor blades7. By rotational movement of the swashplate11, cyclic pitch can be imparted in one direction (ie. pitch or roll).

In some embodiments, swashplate rotor10can be mounted to swashplate stator11using ball bearing26. In some embodiments, master pitch link9can connect swashplate rotor10to one blade grip20. This link can provide a driving torque from blade grip20to swashplate rotor10and can synchronize the position and speed of rotation between motor rotor3and swashplate rotor10.

In some embodiments, a slave pitch link8can connect swashplate rotor10to the remaining blade grip20. Slave pitch link8does not impart or receive any driving torque from either swashplate rotor10or blade grip20.

Referring toFIG.5, in some embodiments, master pitch link9can comprise ball joint23and two flange ball bearings24. Ball joint23can permit rotational movement about a point of rotation. Flange bearings24can restrict rotational movement to about the axis of the flange bearings. This allows a force to be imparted to master pitch link9in the direction of the axis of flange bearings24.

Referring toFIG.6, in some embodiments, slave pitch link8can comprise two ball joints25. This means that no lateral force can be applied to link8from either swashplate rotor10or blade grip20.

The advantages of the master-slave pitch link arrangement are not immediately obvious. Consider a scenario where both pitch links are “master pitch link” design. In that scenario, any flapping of blade grip20about flapping pin17axis causes a rotational movement of the master pitch link about the flapping pin as well. This movement is transferred via the pitch link to swashplate rotor10. If the magnitude of flapping of each blade grip is different (which occurs during cyclic pitch events) this introduces stress into all pitch link components. By replacing one of the master pitch links with a slave pitch link, the force cannot be transmitted from one blade grip to the other and, thus, no stress can be introduced into the system when blade flapping occurs.

Overview of a Coaxial System

Referring toFIG.7, one embodiment of a coaxial helicopter is shown. In this embodiment, coaxial helicopter30can be manufactured by mounting two rotor systems31aand31bthereon in a coaxial arrangement. While various configurations comprising two rotor systems can be employed, in all cases, one rotor system must rotate in a clockwise direction and the other rotor system must rotate in a counter clockwise direction. In some embodiments, one rotor system can control the roll direction cyclic pitch and the other rotor system can control the pitch direction cyclic pitch.

In some embodiments, altitude of helicopter30can be controlled by increasing or decreasing the collective pitch to both rotor systems31aand31b. In some embodiments, roll cyclic pitch on one of the rotor systems can control the roll of the aerial vehicle, In some embodiments, pitch cyclic pitch on the other rotor system can control the pitch of the aerial vehicle. In some embodiments, yawing the aerial vehicle can be accomplished by reducing the torque output of one motor while increasing torque of the other. In some embodiments, torque output of the motor can be modified by either changing speed of the rotor, changing collective pitch of the rotor or a combination of both.

Overview of a Tandem System

Referring toFIG.8, one embodiment of tandem helicopter system32is shown. In this embodiment, helicopter32can be manufactured by mounting two rotor systems31aand31bthereon in a tandem arrangement. The two rotor systems must rotate in opposite directions relative to each other. In this embodiment, cyclic pitch direction for the two rotor systems can be both in the roll axis of the aerial vehicle.

In some embodiments, altitude of helicopter32can be controlled by increasing or decreasing the collective pitch to both rotor systems31aand31b. In some embodiments, pitch of the aerial vehicle can be controlled by increasing the collective pitch on one rotor system and decreasing the collective pitch on the other. In some embodiments, roll control can be controlled by increasing or decreasing roll cyclic pitch on both rotor systems simultaneously and with equal magnitude. In some embodiments, yawing the aerial vehicle can be controlled by introducing roll cyclic pitch on one rotor system while introducing roll cyclic pitch of an equal magnitude but opposite direction on the other rotor system.

Embodiments implemented in computer software can be implemented in software, firmware, middleware, microcode, hardware description languages, or any combination thereof. A code segment or machine-executable instructions can represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A code segment can be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. can be passed, forwarded, or transmitted via any suitable means including memory sharing, message passing, token passing, network transmission, etc.