Electric coaxial rotor aircraft

Abstract

The invention relates to an electric coaxial rotor aircraft. The electric coaxial rotor aircraft is characterized by comprising two rigid structures which are connected through a hinge mechanism. Wherein the upper structure is provided with an outer rotor motor, two rotor wings, a set of reverse rotating device and an air guide plate; the lower structure bears a load cabin and / or a cockpit, a flight control system and an energy storage system.

Description

Background Art

[0002] Helicopters use a rotor structure and can achieve vertical takeoff and landing without a runway. Their hover capability gives them significant advantages in patrol and emergency missions.

[0003] To achieve horizontal flight, a helicopter needs to convert part of its thrust into a forward component. However, as the flight speed increases, due to the increasing lift asymmetry between the advancing and retreating blades, the system will show obvious imbalance. To reduce the resulting overturning moment, a hinged mechanism is usually set at the root of the rotor and controlled by periodically adjusting the blade angle of attack.

[0004] To reduce the impact of the lift difference between the advancing and retreating blades, a coaxial rotor structure can be used. Another advantage of this rotor structure is that the overall layout is more compact due to the elimination of the tail rotor. For example, both Kamov and Sikorsky have developed coaxial rotor aircraft.

[0005] Technological development has led to the emergence of high-speed helicopters with rigid coaxial rotors, such as the S59 / S69 models using the Advancing Blade Concept (ABC). Related patents have also emerged. For example, US Patent No. 5,058,824 proposes a control system, and EP 2803570A1 proposes the use of a Higher Harmonic Control (HHC) system to reduce vibration.

[0006] The said system is not applicable to ultra-light aircraft and cannot meet the requirements of high-speed flight.

[0007] In addition to controlling the flight attitude by adjusting the pitch of the rotor blades, another control method applicable to coaxial rotor aircraft is to tilt the axis of rotation relative to the airframe and generate pitch and roll moments by shifting the center of gravity. This control system has a simple structure and is especially suitable for low-speed aircraft. According to the regulations of the Federal Aviation Administration (FAA) and the Experimental Aircraft Association (EAA) in the United States, the speed limit for ultra-light aircraft is 55 knots (about 63 miles per hour), and this speed range provides conditions for the feasibility of this control method. US Patent No. 3,554,467 authorized to Yowell Company in 1968 discloses such a system, in which the movement of the helicopter is controlled by tilting the rotor system.

[0008] The movement in other directions is controlled by deflecting the airflow through a large rotatable external wing surface hinged at the bottom of the helicopter. US Patent No. 5,370,341 authorized to Leon Company in 1994 discloses a control system in which the pilot changes the relative position of his own center of gravity and the center of gravity of the aircraft through a joystick to achieve the pitch and roll of the helicopter. The tail assembly of the aircraft provides yaw control during forward flight.

[0009] The U.S. Patent No. US 4,787,573 licensed to Pauchard discloses another control system for helicopter pitch and roll. The pilot, seat, and fuel tank of the aircraft can only slide coplanarly along a set of parallel sliding rods within the nacelle. Pitch control is mainly achieved by moving the counterweight, and roll control is accomplished by differential braking of the rotor disc.

[0010] The U.S. Patent No. US 3,722,830 discloses a coaxial contra-rotating rotor helicopter, which is provided with a motor (two in total) near each rotor. The motor is installed on the support structure, and through this structure, its center of gravity is kept at a certain offset distance from the rotation axis of the rotor. The support mechanism can rotate around the axis, and by adjusting the relative position of the center of gravity of the aircraft and the rotor axis, the target translational thrust can be obtained.

[0011] In these simplified systems, there is no need for cyclic pitch control or collective pitch control. By deflecting the coaxial rotor configuration and adjusting the rotor speed, the three-axis combined control of the aircraft's pitch, roll, and lift is achieved.

[0012] The similar rudder-like deflectable wing surface has good control effect when the aircraft has a relatively high forward flight speed, but its control efficiency is significantly reduced during hovering or low-speed flight.

[0013] In the aircraft structures protected by other patents such as US201462058424 and EP 2265495B1, the lift is provided by the coaxial contra-rotating rotors of the vertical axis, and the translational thrust is provided by the rotors of the horizontal axis.

[0014] The U.S. Patent No. US2,462,182 (torpedo propulsion system for coaxial contra-rotating rotors) licensed to Westinghouse Electric Corporation in 1949 discloses a special motor structure: its motor housing can synchronously drive the excitation component and the armature to rotate, and electrical energy is transmitted through the slip ring-brush assembly. The motor housing coaxially extends two hollow output shafts rotating in opposite directions, which are respectively connected to the magnetic field part and the armature part. This motor architecture enables a certain relative rotational speed between the two rotating components; however, when the loads of the two rotors are different, their absolute rotational speeds will not be equal.

[0015] In terms of conventional drive systems and their reduction ratio technologies, although the first magnetic gear can be traced back to the early 20th century (such as Armstrong's electromagnetic spur gear), it was not until Martin's US 3,378,710 patent in the 1960s and the more recent US2011 / 0037333 A1 patent by Atallah et al. that a transmission performance with significant torque density (exceeding 100 kNm / m3) comparable to mechanical gears was achieved. In such gear structures, the iron pole pieces provided not only reduction ratio control but also the ability to reverse the direction of rotation.

[0016] As shown in the prior art, there is still a need to develop a helicopter solution that integrates the advantages of an electric motor and a simplified control system, which needs to be adapted to a multi-energy storage system, has economic advantages, and can meet the airworthiness weight limit requirements for ultra-light aircraft. According to the empty mass upper limit (254 pounds) set by the Federal Aviation Administration (FAA) and the Experimental Aircraft Association (EAA) for ultra-light aircraft, "manned" drones with a quadcopter or more configuration usually have difficulty meeting this airworthiness standard.

[0017] Subject Matter and Summary of the Invention

[0018] This section provides an overall overview of the disclosure of the present invention and should not be construed as a complete or exhaustive listing of all elements, content, features, or advantages of the present invention.

[0019] The present invention proposes a helicopter with coaxial counter-rotating rotors, which includes two rigid structures connected by a hinge device. Among them, the upper structure is fixed with components such as an outer rotor motor, a counter-rotating system, two rotors, and an air deflector; the lower structure includes a cabin for carrying payloads and / or pilots, a flight control system, an energy storage system, and devices for the takeoff, landing, support, and ground movement of the aircraft.

[0020] The total mass fixed to the lower structure is greater than the total mass fixed to the upper structure.

[0021] The operation of the aircraft is achieved by the airflow generated by the rotors and the tilt angle of the rotor shaft relative to the lower structure. The hinge device connecting the upper and lower structures can use a simple cylindrical hinge with its rotation axis parallel to the pitch axis (Y-axis); or two cylindrical hinges can be used to enable it to rotate around the pitch axis (Y-axis) and the roll axis (X-axis). In the case of using a single hinge, only the relative pitch angle between the upper and lower structures can be controlled; while using a double hinge, the pitch and roll angles can be controlled simultaneously, thus achieving more precise attitude control.

[0022] The air deflector is installed on the upper structure, below the rotor, and can tilt and rotate around an axis parallel to the roll axis (x-axis). To achieve yaw and roll control, most of the surface of at least one deflector should be in front of the rotor rotation axis, and most of the surface of the other deflector should be behind the rotation axis. During yaw control, the front and rear deflectors tilt in opposite directions; during roll control, the front and rear deflectors tilt in the same direction.

[0023] The motor includes a stator fixed to the upper structure and an outer rotor; the outer rotor contains elements for fixing at least one rotor. The other rotor is fixed to the counter-rotating system.

[0024] The rotation reverse system of the second rotor can be achieved by a mechanical or magnetic device connected to the first motor rotor, or by a second motor coaxial with the first motor and with its stator fixed to the upper structure. In the case of using a single motor, its rotor drives both rotors simultaneously and ensures the proportional relationship of their speeds. By designing the two rotating components to have inversely proportional moments of inertia, even when a sudden braking occurs due to a failure, equal and opposite angular momenta can still be achieved.

[0025] If the second rotor is driven by a second motor, the speeds of the two rotors must be jointly controlled to maintain balance around the Z-axis. Although the dual-motor system simplifies the counter-rotating mechanism, more rigorous design is required to cope with possible failures in either of the two motors or their speed control systems.

[0026] A mechanical or magnetic reduction mechanism can be provided between the motor and the rotor, and this reduction mechanism can also be integrated with the counter-rotating system.

[0027] The control system includes actuators for adjusting the inclination angle of the upper structure relative to the lower structure, actuators for adjusting the inclination angle of the deflector, and actuators for adjusting the motor speed.

[0028] For ultra-light aircraft, all flight control systems can adopt a pure mechanical and manual operation mode because the aerodynamic forces they bear are small. A hydraulic or electric control system can also be configured, and even a fly-by-wire (FBW) system can be integrated.

[0029] This structural design keeps the two rotors at an appropriate axial distance, thus improving the overall aerodynamic efficiency. Since the speed and direction of the airflow received by the lower rotor are different from those of the upper rotor, the pitches of the two rotors can be set differently. To reduce noise, the sizes, numbers of blades, and rotational speeds of the two rotors can also be different. Using outer-rotor motors (including radial-flux type and axial-flux type) can achieve a high torque / mass ratio and is suitable for various application scenarios directly coupled with the rotor.

[0030] Placing the motor in the upper structure can avoid the design of a long transmission shaft that conventionally extends from the motor to the rotor; such a transmission shaft may pose safety hazards during high-speed rotation and requires corresponding protective devices.

[0031] The motor controller can be connected to either the upper structure or the lower structure. In either case, the driving of the motor depends only on the power line, control line, and necessary data lines transmitted between the upper and lower structures.

[0032] The air deflector disposed near the rotor slipstream region has the following advantages: providing more effective yaw control in hover and level flight states and assisting in roll control; helping to direct the slipstream along the z-axis direction, thereby enhancing the efficiency of the rotor. In addition, the deflector can also provide a certain degree of safety protection for the rotating components of the rotor.

[0033] Brief Description of the Drawings This invention will be described with reference to the non-limiting embodiments shown in the drawings, which are for illustrative purposes only. The drawings show some aspects and embodiments of the invention, and where necessary, similar structures, components, materials, and / or elements in different drawings are indicated with the same reference numerals.

[0034] Figure 1 Is a left side view of a coaxial helicopter according to the present invention.

[0035] Figure 2 Is a schematic diagram of an outer rotor motor.

[0036] Figure 3 Is a schematic diagram of some components of the system of the present invention.

[0037] Figure 4 Is a schematic diagram of a magnetic reducer / reverser.

[0038] Detailed Description of the Invention

[0039] Although the present invention may be subject to various modifications or take other configurations, some of its preferred embodiments are shown in the drawings and will be described in detail below. However, it should be understood that the present invention is not limited to the illustrated embodiments, but is intended to cover all modifications, alternative configurations, and equivalent variations within the scope of the appended claims. In the drawings and element descriptions, an orthogonal coordinate system is used: the coordinate axes fixedly connected to the lower structure are represented by capital letters X, Y, and Z, and the coordinate axes fixedly connected to the upper structure are represented by lowercase letters x, y, and z. The origin of both is located at the hinge rotation center connecting the upper and lower structures, where X, Y, Z and x, y, z respectively correspond to the roll axis, pitch axis, and yaw axis.

[0040] The external rotor motors described in this specification include axial flux motors, radial flux motors, and motors with integrated mechanical or magnetic reduction systems.

[0041] The magnetic gear, magnetic reducer, or magnetic inverter refers to a device that includes at least two rotors with a certain number of magnetic poles; the device may include an intermediate iron magnetic pole, and the rotational speeds between its rotors are inversely proportional to their respective numbers of magnetic poles.

[0042] The aerodynamic deflector refers to a wing surface or blade with a specific aerodynamic shape, which can be used to deflect or guide the surrounding fluid to achieve the best guiding effect.

[0043] The propeller or rotor refers to a propulsion unit that includes two or more blades with an aerodynamic shape and a hub that fixes the blades to a rotating shaft. The energy storage system refers to a device that can store and release energy, such as a battery, fuel cell, or fuel. In the case of using fuel, the system also includes an internal combustion engine for converting fuel energy into mechanical energy and a power generation device for converting mechanical energy into electrical energy.

[0044] The connection cables for electricity, power supply, data, and actuator control are not shown in the drawings.

[0045] Refer to Figure 1 , the present invention is implemented in a helicopter (10) which is provided with a lower structure (11) for carrying several components, including a support (21) for landing and ground movement, a payload (22) and / or a pilot (23), a control system (24), and an energy storage system (25).

[0046] The upper structure (13) is connected to the lower structure (11) through a hinge (12). The hinge further fixes several components, including a motor (30), a rotation inversion system (33), two coaxial and counter-rotating rotors (34) and (35), and aerodynamic deflectors (37) and (38). In this embodiment, the motor (30) is located between the two rotors (34) and (35) and is connected to a controller (50) through components including a cable (power cable and possible data cables). The controller controls the power supply and driving of each phase of the motor according to instructions to achieve the target rotational speed. The motor (30) can also be arranged below the two rotors. The controller (50) can be fixed on the structure (11) or the structure (13) and is connected to the energy storage system (25) and the control system through cables. Figure 1Also shown are actuator brackets (15) and (17) for controlling pitch changes, which are respectively fixed to structure (13) and structure (11); and actuator brackets (14) and (16) for controlling roll changes, which are also respectively fixed to structure (13) and structure (11). The rotor (34) includes blades (45), which are fixed to the upper part of the outer rotor (31).

[0047] As Figure 2 more clearly shown, the electric motor (30) includes an outer rotor (31) and a stator (32). Figure 2 Two types of outer rotor motors are schematically shown, one is a radial flux type (Figure a), and the other is an axial flux type (Figure b). Both of these motors are provided with connectors (311) for fixing rotating components (such as rotors) on the rotors (31) on both sides of the engine (30). The stator of the motor (32) includes elements (321) for fixing it to the structure (13), and elements (322) for electrical connection. As Figure 3 shown, the upper structure (13) includes an external cylindrical component (39), which is coaxial with the rotor rotation axis z; a bearing (41) is provided on the cylindrical component for supporting the rotating structure (40). The bevel gear (42) and the hub (45) of the lower rotor (35) are fixed to the rotating structure (40). The rotation reversing system (33) is fixed to the lower part of the rotor (31). In Figure 3 the shown embodiment, the system includes a bevel gear (44) that rotates around the rotation axis z, and this gear transmits power through one or more bevel gear pinions (43) that mesh with the bevel gears (42) and (44). The pinion (43) can rotate around an axis perpendicular to the axis z and is fixed to the structure (13). Obviously, the rotation reversing system can also adopt other configuration methods, such as achieving the opposite rotation of the two rotors through a planetary gear mechanism.

[0048] In some applications, magnetic gears can be used instead of gear transmissions to transmit torque. Figure 4 An example of an axial flux type magnetic reversing and decelerating system is shown, in which a magnetic wheel (64) is fixedly connected to the rotor (31) of the electric motor, and this magnetic wheel includes a number of magnets (641), the magnetic pole directions of which are parallel to the rotation axis z; another magnetic wheel (62) is also fixedly connected to the rotating structure (40) of the electric motor, and this magnetic wheel also includes a number of magnets (621), and the magnetic pole directions are also parallel to the rotation axis z. A magnetic wheel (63) is provided between these two magnetic wheels, and this magnetic wheel is fixed to the structure (13) and is provided with a number of iron magnetic poles (631). The iron magnetic poles (631) arranged in this way can reverse the rotation direction of the magnetic wheel (62) relative to the wheel (64). By setting different pole number wheel sets, different reduction ratios can be achieved.

[0049] The rotation reverse system of the second rotor can also be achieved by setting a second motor coaxial with the first motor, and its stator is fixed to the upper structure.

[0050] Similar to the rotation reverse device, the reduction gear can also adopt various configuration methods to obtain the required reduction ratio. Figure 1 The air deflectors (37) and (38) shown in the figure are used for yaw control and can also be used for roll control. They are fixed to the upper structure (13), arranged in the air flow channel, and their rotation axes are parallel to the x-axis. Most of the surface area of at least one deflector (such as 38) is located in front of the rotor rotation axis z, while most of the surface area of the other deflector (such as 37) is located behind this axis. Figure 3 The support (36) for fixing the deflector to the structure (13) and the connecting arm (46) for connecting the deflector to the connectors (47) and (48) for controlling the rotation are also shown.

[0051] According to the application requirements of the aircraft, the upper structure (13) can be hinged to the lower structure (11) through a cylindrical hinge (12), and this hinge only allows the two to rotate relative to each other around the common axis Y–y, as Figure 3 shown; or, as Figure 1 shown, a universal joint hinge or a double-cylindrical cross hinge can be adopted to enable it to achieve bi-axial rotation around the Y–y axis and the X–x axis at the same time. During the entire flight process from takeoff to landing, the aircraft is controlled by the actuator. For a helicopter using a single cylindrical hinge (12), the control methods include: achieving thrust control by controlling the rotational speed of the engine (30); achieving pitch control by controlling the rotation around the hinge (12); achieving roll control by controlling the same-direction rotation of the air deflectors (37) and (38); achieving yaw control by controlling the reverse rotation of the deflectors (37) and (38). For a helicopter using a double hinge (12), the aircraft is controlled by the actuator, including: achieving thrust control by controlling the rotational speed of the engine (30); achieving pitch control by controlling the rotation of the upper structure (13) around the Y axis; achieving roll control by controlling the rotation of the upper structure (13) around the X axis; achieving yaw control by controlling the reverse rotation of the air deflectors (37) and (38). In both of the above cases, the speed control of the aircraft is jointly determined by the pitch angle and the thrust value. As Figure 1As shown, a mechanical manual flight control system can be realized, which includes a joystick (80) and a throttle device (not shown), facilitating the pilot (23) to control. When the joystick (80) rotates around an axis parallel to the Y-axis, it can control the pitching rotation of the superstructure (13) around the Y-axis; when the joystick (80) rotates around an axis parallel to the X-axis, it can control the rolling rotation of the superstructure (13) around the X-axis. In addition, the reverse control of the air deflectors (37) and (38) can be realized by the rotation of the joystick itself around its axis or by other structures fixedly connected thereto, thereby achieving yaw control.

Claims

1. An aircraft, comprising: - Two rigid structures, upper and lower, connected by hinges; - an electric motor; - a counter-rotation system; - Two coaxial counter-rotating rotors; - at least two air deflectors; -A control system and an energy storage system; Features: - The upper structure is fixedly provided with an outer rotor motor, two coaxial counter-rotating rotors and an air deflector; - The substructure is provided with a load compartment and / or a cockpit, a control system, an energy storage system and devices for taking off and landing, supporting and moving the aircraft on the ground; - the total mass fixed to the substructure is greater than the total mass fixed to the superstructure; - the electric motor comprises a stator connected to the superstructure and an outer rotor; - the air deflector is arranged near the airflow area of ​​the lower rotor and can rotate around an axis parallel to the roll axis of the superstructure; - the majority of the surface area of ​​at least one air deflector is located in front of the rotor axis of rotation and the majority of the surface area of ​​at least another air deflector is located behind the rotor axis of rotation. - the upper rigid structure is capable of rotating relative to the lower rigid structure about at least one axis parallel to the pitch axis; Wherein, the control system comprises: - an actuator for controlling the rotation of the upper structure relative to the lower structure; - an actuator for adjusting the speed of the motor rotor; - an actuator for rotating at least one front air deflector in opposite directions to at least one rear air deflector.

2. The coaxial rotor aircraft according to claim 1, wherein a hinge mechanism is added to enable the upper structure to rotate relative to the lower structure around an axis parallel to the roll axis, and the control system includes an actuator for rotating the upper structure relative to the lower structure around the pitch axis and the roll axis.

3. The coaxial rotorcraft of claim 1, wherein the counter-rotating system comprises a magnetic gear.

4. The coaxial rotorcraft according to claim 1, wherein the counter-rotating system includes another electric motor and its corresponding control system.

5. The coaxial rotor aircraft according to claim 1, wherein a reduction gear device is provided between the motor rotor and the rotor.

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