GB2503273A

GB2503273A - Aircraft with tilting rotor shaft

Info

Publication number: GB2503273A
Application number: GB201211025A
Authority: GB
Inventors: Andrew Macdonald
Original assignee: TRADE ELECTRICS UK Ltd
Current assignee: TRADE ELECTRICS UK Ltd
Priority date: 2012-06-21
Filing date: 2012-06-21
Publication date: 2013-12-25
Anticipated expiration: 2032-06-21
Also published as: GB2503273B; GB201211025D0; WO2013190330A1

Abstract

An unmanned aircraft 1 includes a lift apparatus comprising a rotor having rotor blades 4,5 mounted upon a rotor shaft 3A,3B rotatable to turn the rotor blades to generate a lift force for the aircraft. A drive apparatus 10 is connected to the rotor shaft and arranged to be selectively energised to rotate the rotor shaft thereby to turn the rotor blades. The rotor shaft is pivotaly connected to a body part 2. A tilt actuator 17 is arranged within the aircraft for selectively applying a force to the rotor shaft in a direction transverse to the axis of the rotor shaft to tilt the rotor shaft relative to the body part about said pivoting connection thereby to selectively tilt the direction of said lift force relative to the body part when the drive apparatus is energised to turn the rotor blades such that said lift force acquires a transverse component.

Description

Improvements in and Relating to Aircraft The invention relates to aircraft such as, although not exclusively, unmanned aircraft such as toy aircraft (e.g. a toy or model helicopter). By unmanned, it is meant that the aircraft is designed and intended to fly without a pilot in situ in the aircraft. Piloting of the aircraft may be performed remotely.

A concern in relation to unmanned aircraft, such as model and toy aircraft is the provision of sufficient motive power at minimal weight. Another concern is reducing the cost and complexity of manufacture. The present invention aims to address these matters.

An unmanned aircraft including a lift apparatus comprising a rotor including rotor blades mounted upon a rotor shaft rotatable to turn the rotor blades to generate a lift force for the aircraft, a drive apparatus connected to the rotor shaft and arranged to be selectively energised to rotate the rotor shaft thereby to turn the rotor blades, and a body part to which the rotor shaft is pivotingly connected. A tilt actuator is arranged within the aircraft for selectively applying a force to the rotor shaft in a direction transverse to the axis of the rotor shaft to tilt the rotor shaft relative to the body part about said pivoting connection thereby to selectively tilt the direction of said lift force relative to the body part when the drive apparatus is energised to turn the rotor blades such that said lift force acquires a transverse component. As a result, the lift apparatus may me employed to provide some or all of the transverse motive thrust of the aircraft (e.g. forward thrust). The force applied to the rotor shaft by operation of the tilt actuator may preferably be a force applied indirectly, such as a force generated by the actuator and transferred of imparted to the rotor shaft via intermediate components of the aircraft, such as a bearing surface connected to the rotor shaft, or connected to body part, against which the tilt actuator may act. For example, the bearing surface may be rigidly connected to the body part and the tilt actuator rigidly connected to the rotor shaft. The tilt actuator may be arranged to apply (via a controllably moveable part thereof) a force to the bearing surface directly with the result that a reactive force is applied to the tilt actuator which is thus also applied to the rotor shaft rigidly connected to the tilt actuator.

The tilt actuator may include an eccentric bearing part connected to the rotor shaft via a bearing pivot to which it is mounted for selectively rotating the eccentric bearing part about the bearing pivot to urge against a bearing surface connected to the body part to urge the rotor shaft to tilt relative to the body part in reciprocation of the rotation of the eccentric bearing part.

The eccentric part may be rotatingly mounted (directly or indirectly) in connection with a motor for rotating the eccentric. For example, the eccentric part may be directly mounted upon the axle of a motor to rotate about that axle when the motor is energised. Alternatively, the axle of the motor may be mechanically coupled to the eccentric indirectly via one of more gears, pulley loops, or other couplings which transfer rotational motion of the motor axle into rotation/pivoting motion of the eccentric part. As a result a simple motor may be used to implement the tilt actuator. Alternatively, the tilting actuator may include a linear actuator including a bearing part connected to the rotor shaft for selectively moving the bearing part linearly to urge against a bearing surface connected to the body part to urge the rotor shaft to tilt relative to the body part in reciprocation of the linear motion of the eccentric bearing part.

The tilt actuator may include a crank or cam connected to the rotor shaft via a motor for selectively rotating the crank/cam part to urge against a bearing surface connected to the body part to urge the rotor shaft to tilt relative to the body part in reciprocation of the rotation of the crank/cam part. That is, the crank or cam may provide the eccentric bearing part.

Alternatively, when the tilt actuator comprises a linear actuator, the linear actuator motor may be arranged for selectively pushing against a bearing surface connected to the body part to urge the rotor shaft to tilt.

The bearing surface part may comprise two opposed bearing surfaces against which the eccentric bearing part is selectively rotatable to urge in a respective one of two opposite directions to selectively to urge the rotor shaft to tilt in a respective one of two opposite directions relative to the body part in reciprocation of the rotation of the eccentric bearing part.

The eccentric bearing part may be arranged to rotate about an axis (e.g. the bearing pivot axis) substantially transverse to the rotor shaft. This provides that the tilt urged by the rotation of the eccentric may provide an urging force substantially transverse to the rotor shaft thereby able to generate a torque thereupon. The aircraft may include a return mechanism connected to the rotor shaft and arranged to urge the eccentric bearing part to a quiescent position from which it is tiltable by action of said rotation of the eccentric bearing part (or linear actuation of a linear actuator of the tilt actuator, alternatively). The return mechanism may comprise one or more springs connecting the rotor shaft and the bearing part of the tilt actuator to urge the bearing part to a quiescent position relative to the rotor shaft. The motor of the actuator is preferably arranged to act against (and overcome) the return mechanism when energised, thereby to move the bearing part from the quiescent position, and to be acted upon (and overcome) by the return mechanism when not energised such that the bearing part is returned to the quiescent position.

The rotor shaft is preferably pivotingly connected to the body part at a location along the rotor shaft. The pivot connection is preferably located between the drive apparatus and the rotor connected thereto. This results in the weight if the drive apparatus being suspended below the pivot connection in normal use of the aircraft which greatly assists in absorbing/reducing vibration in the drive and lift apparatus in use. The configuration is mechanically more stable than a configuration in which the weight of the drive apparatus is located above the pivot connection.

The unmanned aircraft may include a housing for retaining a power source for providing power to energise the drive apparatus wherein the housing is located in a base of the body part. This lower, or lowermost positioning provides a counter-weight to the tilting forces/torques imparted upon the rotor shaft by the tilt actuator to enable the orientation of the body part to remain relatively little (or at least minimally) changed in reaction to the tilting torques.

The rotor may include a coaxial rotor comprising a pair of separate rotors mounted coaxially one above the other on the rotor shaft and connected to the drive apparatus to be turned simultaneously thereby in opposite respective directions. The aircraft may comprise no tail rotor. The coaxial rotor may be the only rotor of the aircraft.

The unmanned aircraft may include a control unit for controlling the drive apparatus and the tilt actuator in response to remotely generated control signals received thereby, and a wireless receiver apparatus for receiving said remote control signals wirelessly and inputting the received signals to the control unit.

The invention may provide a remotely controllable toy aircraft kit comprising an unmanned aircraft described above and a remote control unit including a control signal generator arranged to generate said control signals for remotely controlling the drive apparatus and the tilt actuator in response to a user input, and transmitter apparatus arranged to receive the control signals generated by the remote control unit and to transmit the remote control signals wirelessly.

There now follow non-limiting embodiments of the invention provided as examples to aid and understanding with reference to the accompanying drawings, of which: Figure 1 illustrates a side view of a remote-controlled toy helicopter according to an embodiment of the present invention; Figure 2 illustrates the toy helicopter of Figure 1 in which the body part is schematically shown in cross-section to reveal the elements housed within the body part; Figure 3 illustrates, in isolation, the drive apparatus and tilt apparatus housed within the body part of the toy helicopter of Figure 2, in isolation; Figure 4 shows a side and perspective view of the tilt operators and drive apparatus illustrated in Figure 3; Figure 5 illustrates the drive apparatus and tilt apparatus of Figure 3 in one of two extreme tilt positions; Figure 6 illustrates a top view of the toy helicopter shown in Figure 1.

In the drawings like items are assigned like reference symbols for consistency.

Figure 1 illustrates a remotely controllable toy helicopter (1) comprising a hollow body part (2) consisting of a domed shell mounted atop a platform (9, Figure 2) at the base of the body part below which a set of four feet (7) extend. A lift apparatus extends from within the body part through an elongate slot formed in the top of the domed shell and comprises a coaxial rotor comprising a pair of separate rotors (4,5) mounted coaxially one above the other on a respective one of a pair of coaxial rotor shafts connected to a drive apparatus (10, Figure 2).

The drive apparatus is mounted within the body part of the helicopter within the hollow of the domed shell (2). The respective separate rotors of the coaxial rotor are arranged to be turned simultaneously by the drive apparatus in opposite respective directions. A lower rotor of the pair of coaxial rotors (4) is fixed to a first rotor shaft (3A) of the pair of coaxial rotor shafts while the upper, second, rotor of the pair of coaxial rotors is fixed to an end of the second rotor shaft (3B) of the pair of coaxial rotor shafts. The first coaxial rotor shaft (3A) is hollow and comprises a through-bore which extends fully along the central axis of the first coaxial rotor shaft and which is dimensioned to receive a length of the second coaxial rotor shaft (3B) to pass all the way through and along the first rotor shaft. Thus, the first coaxial rotor shaft extends from either end of the first rotor shaft outwardly from the axial bore of that first rotor shaft. A fly bar or stabiliser (6) is mounted atop the second and uppermost rotor (5). A series of four ventilation slots (8) is formed in the top of the domed shell of the body part(S) to permit convective cooling of the drive apparatus (10) mounted within the dome shell immediately below those ventilation slots.

It is to be noted that the toy helicopter possesses no tail rotor.

Figure 2 schematically illustrates the toy helicopter illustrated in Figure 1 but in which the domed shell of the body part (2) is shown transparent or in cross-section to reveal the contents within it.

In particular, the drive apparatus comprises a first electric motor (14A) connected to the first rotor shaft (3A) and arranged to be selectively energised to rotate the first rotor shaft and thereby rotate the first rotor blades (4) mounted upon that shaft. A second electrical motor (14B) is connected to the second rotor shaft (3B) and is also arranged to be selectively energised to rotate the second rotor shaft and rotor blades mounted upon that (5).

Each of the first and second electrical motors possesses a respective drive shaft (1 5A, 1 5B) extending downwardly from the base of the drive apparatus, and possessing a respective drive gear positioned to engage a corresponding secondary gear (16A, 16B) separately mounted coaxially upon the terminal end of a respective one of the first and second coaxial rotor shafts (3A, 3B) at the base of the drive apparatus. The first secondary gear (1 6A) is mounted at the terminal end of the first rotor shaft such that energisation of the first electrical motor (14A) imparts a rotation to the first secondary gear which is imparted to the first rotor blades (4) via the first rotor shaft (3A). Similarly energisation of the second electrical motor (14B) causes rotation of the second (16B) secondary gear and thereby rotation of the second rotor blades (5) via the second rotor shaft (3B).

The drive apparatus is mounted upon the tilt apparatus which comprises a hanging frame part (13) to which the first and second electrical motors are fixed, which is pivotingly suspended from an upper frame part (11) fixed internally to the top of the domed body part at its underside by a series of screws (not shown) passing through screw holes in the upper frame. The hanging frame part (13) is connected to the upper frame part by the first rotor shaft (3A) which is itself pivotingly connected to the upper frame part (11) via a pivot axle(1 2). The pivot axleextends in a direction transverse to the axis of the second rotor shaft (perpendicular to the plane of the page of Figure 2).

Accordingly, the hanging frame part (13) and the drive apparatus mounted upon it (14A, 14B, 15A, 15B, 16A and 16B) are able to swing, as in a pendulum, about the pivot axle (12) with the result that the first rotor shaft (3A) and the second rotor shaft (3B) sheathed within it, may tilt relative to the upper frame part (11) and the body of the toy helicopter to which the upper frame part is fixed. Consequently, the rotor blades (5,6) are thereby able to tilt relative to the body of the helicopter.

A tilt actuator (17) is similarly mounted upon the hanging frame part (13) and is arranged for selectively applying a tilting force to the upper frame part in a direction transverse to the axis of the rotor shaft thereby to induce the hanging frame part to tilt relative to the upper frame part.

This is described in more detail with reference to Figure 3 to 5 herein.

The helicopter further comprises a control unit (19) mounted on the platform (9) of the body part for controlling the drive apparatus and the tilt actuator in response to remotely generated control signals (24) received by a wireless receiver unit (22). The wireless receiver unit of the helicopter which is operably connected to the control unit to pass received control signals to the control unit. The control unit may comprise a circuit board including suitably configured computer chips arranged and adapted to implement the necessary control functions. such as would be readily apparent to a person skilled in the art. A housing (18) is provided at the plaftorm for retaining a battery which serves as a power source for providing power to energise the two electrical motors (14A, 1 4B) of the drive apparatus within the housing. Electrical wires (21) connect the electrical motors of the drive apparatus to the power source via an interface unit (20) for delivery of power to the motors.

The battery housing (18), the control unit (19) and any battery contained within the battery housing are each mounted upon the platform (9) of the body of the helicopter. The wireless receiver apparatus (22) passes through a through-opening formed in the platform surface (9) to permit the signal receiving elements of the receiver to be presented externally of the body of the helicopter.

A remote control unit (23) includes a control signal generator (27) to generate remote control signals (e.g. radio, Infra Red etc) for remotely controlling the helicopter, and particularly the drive apparatus of the helicopter and the tilt actuator within it, in response to a user input via a joystick (25) or the like. The remote control unit comprises a transmitter apparatus (26) arranged to receive the control signals from the control signal generator within the remote control unit, and to transmit those remote control signals wirelessly (24) to the helicopter. The configuration and operation of the remote control unit (23) may be such as would be readily apparent to the skilled person.

Figure 3 illustrates the drive apparatus, hanging and upper frames, and tilt apparatus of the helicopter illustrated in Figure 2. These elements are illustrated in Figures 3, 4 and 5 in isolation for clarity.

The tilt actuator (17) mounted upon the hanging frame part (13) comprises a bearing lug (33) cylindrical in shape and eccentrically mounted to a bearing pivot (34) fixed to the hanging support frame (13) and extending in a direction parallel to the pivot axle (12) of the rotor shaft.

A segment gear (32) provides the connection between bearing pivot (34) and the bearing lug (33). The segment gear comprises a sector of a circular gear wheel having a circularly curved peripheral edge in which gear teeth are formed in a uniform array. The bearing lug (33) projects perpendicular to the outward-facing surface of the circular segment of the segment gear in a direction parallel to, but eccentric from, the axis of the bearing pivot/axle (34). This configuration defines a crank mechanism.

A tilt motor (36, Figure 4) is arranged in mechanical communication with the segment gear (32) via a pair of intermediate gear wheels (40, Figure 4) which culminate with a tilt drive gear (44) which directly interfaces with the segment gear (32) to turn the segment gear about the bearing pivot (34). The tilt motor (36) comprises an electrical motor which is controllably and selectively energisable to turn the tilt drive gear (44) by the intermediate gearing (40) and, thereby, the segment gear (32). A return spring (39) is mounted to the hanging support frame (38) at the bearing pivot and comprises a pair of resiliently deformable spring arms (38,39) which extend from the region of the tilt pivot to opposite respective sides of, a second lug (37) which projects from the reverse face of the segment gear which faces the drive mechanism (14A,14B). That is to say, the second lug is on the opposite side of the segment gear to the bearing lug (33). The quiescent state of the spring (38,39) is such that the two spring arms of the spring are at a relative position of closest/minimal separation. When the segment gear is turned by action of the tilt motor (36), the second lug is caused to partially revolve about the bearing pivot (34) and displace one of the two spring arms. This, in turn, urges the segment gear to return to its initial position corresponding to the quiescent state of the spring. Each respective one of the two spring arms serves this function in respect of each one of the two opposite directions of rotation of the segment gear. The quiescent position is the position illustrated in Figures 2, 3 and 4 in which the bearing lug (33) is in linear alignment with the pivot axle (12) of the tilt assembly, and the bearing pivot (34) of the tilt actuator. This can be regarded as the "un-tilted" position.

The first coaxial rotor shaft (3A) is connected to the upper frame part (11) pivotingly via a pivot axle (12) which is connected to the hanging frame part (13) via an axle bearing connector (35) which receives the innermost terminal ends of two separate tilt axle parts of the pivot axle which are concurrently mounted coaxially upon the upper frame part (11) and are spaced by the axle bearing connector (35) by a space insufficient to admit the rotor shaft pass between.

A pair of separated and opposed bearing surfaces (30,31) project downwardly from the underside of the upper frame part (11) in parallel to each other towards the hanging frame part (13) in a direction and at a position which retains the bearing lug (33) in the separation between the bearing surfaces. Rotation of the segment gear causes the bearing lug (33) to bear against one of the two bearing surfaces (30,31), depending on the direction of rotation of the segment gear.

Figure 5 illustrates the consequences of such a rotation. In particular, the bearing lug (33) is urged against one bearing surface (31) by rotation of the segment gear in the clockwise sense illustrated in Figure 5 thereby to impart against that bearing surface a force which urges the hanging frame part (13), and the drive apparatus and rotor shaft mounted upon that, to rotate about the tilt pivot access (12) in a clockwise sense. This rotation is permitted to be continuous by virtue of the unobstructed channel or slot formed between (and defined by) the separation of the opposing bearing surfaces (30,31) which permit the bearing lug (33) to travel along the channel or slot as the segment gear is rotated. All the while, the bearing lug is able to bear against the aforementioned bearing surface and apply the force which results in the tilting of the rotor shaft. Conversely, rotating the segment gear (32) in the opposite (e.g. anticlockwise) direction results in a bearing force against the opposite bearing surface (30) and the result is a tilt of the rotor shaft in the opposite (anticlockwise) sense to that shown in Figure 5.

It is reiterated that the rotation of the segment gear is put into effect by rotation of the tilt drive gear (34) which, in turn, is rotated by energising the tilt motor (36) appropriately.

In this way, a tilt may be applied to the lift apparatus, and the rotor blades comprising that apparatus (5,6) relative to the body and housing (2) of the helicopter. This enables the otherwise vertical lift force generated by the lift apparatus to acquire a transverse component which provides a forward/transverse thrust.

Figure 6 illustrates a top view of the toy helicopter which shows a tilt slot (60) formed at the top of the domed shell part (2). The slot extends in a direction perpendicular to the axis of the tilt axle (12) of the drive assembly such that the tilting of the rotor shaft illustrated in Figure 5, for example, can be accommodated without obstruction by the domed shell (2) of the body part.

The embodiments and examples described herein with reference to the drawings are intended for illustrative purposes in order to aid understanding. It is to be appreciated that modifications, variants and equivalents to the examples described herein, such as would be readily apparent to the skilled person, are encompassed within the scope of the invention, such as is defined by the claims.

Claims

CLAIMS: 1. An unmanned aircraft comprising: a lift apparatus comprising a rotor including rotor blades mounted upon a rotor shaft rotatable to turn the rotor blades to generate a lift force for the aircraft; a drive apparatus connected to the rotor shaft and arranged to be selectively energised to rotate the rotor shaft thereby to turn the rotor blades; a body pad to which the rotor shaft is pivotingly connected; a tilt actuator arranged for selectively applying a force to the rotor shaft in a direction transverse to the axis of the rotor shaft to tilt the rotor shaft relative to the body part about said pivoting connection thereby to selectively tilt the direction of said lift force relative to the body pad when the drive apparatus is energised to turn the rotor blades such that said lift force acquires a transverse component.
2. An unmanned aircraft according to any preceding claim in which the tilt actuator includes an eccentric bearing pad connected to the rotor shaft via a bearing pivot to which it is mounted for selectively rotating the an eccentric bearing pad about the bearing pivot to urge against a bearing surface connected to the body pad to urge the rotor shaft to tilt relative to the body part in reciprocation of the rotation of the eccentric bearing part.
3. An unmanned aircraft according to claim 2 in which the bearing surface pad comprises two opposed bearing surfaces against which the an eccentric bearing part is selectively rotatable to urge in a respective one of two opposite directions to selectively to urge the rotor shaft to tilt in a respective one of two opposite directions relative to the body part in reciprocation of the rotation of the an eccentric bearing part.
4. An unmanned aircraft according to claim 2 of claim 3 in which an eccentric bearing pad is arranged to rotate about an axis transverse to the rotor shaft.
5. An unmanned aircraft according to any of claims 2 to 4 including a return mechanism connected to the rotor shaft and arranged to urge the an eccentric bearing pad to a quiescent position from which it is tiltable by action of said rotation of the an eccentric bearing part.
6. An unmanned aircraft according to any preceding claim in which said rotor shaft is pivotingly connected to the body part at a location along the rotor shaft between the drive apparatus and the rotor connected thereto.
7. An unmanned aircraft according to any preceding claim including a housing for retaining a power source for providing power to energise the drive apparatus wherein the housing is located in a base of the body part.
8. An unmanned aircraft according to any preceding claim in which the rotor includes a coaxial rotor comprising a pair of separate rotors mounted coaxially one above the other on the rotor shaft and connected to the drive apparatus to be turned simultaneously thereby in opposite respective directions.
9. An unmanned aircraft according to any preceding claim comprising a control unit for controlling the drive apparatus and the tilt actuator in response to remotely generated control signals received thereby, and a wireless receiver apparatus for receiving said remote control signals wirelessly and inputting the received signals to the control unit.
10. A remotely controllable toy aircraft kit comprising the unmanned aircraft according to claim 9 and a remote control unit including a control signal generator arranged to generate said control signals for remotely controlling the drive apparatus and the tilt actuator in response to a user input, and transmitter apparatus arranged to receive the control signals generated by the remote control unit and to transmit the remote control signals wirelessly.
11. An unmanned aircraft substantially as described in any one embodiment hereinbefore with reference to the accompanying drawings.