WO2024025491A1

WO2024025491A1 - In-line, in-propeller coaxial electric motor group and drive system for aircrafts

Info

Publication number: WO2024025491A1
Application number: PCT/TR2022/051422
Authority: WO
Inventors: Bulent ORAN
Original assignee: Oran Bulent
Priority date: 2022-07-28
Filing date: 2022-12-06
Publication date: 2024-02-01
Also published as: TR2022011942A2

Abstract

The invention relates to motor groups consisting of electric motors for use in electric aircraft and the propulsion system that drives and manages them. Every electric motor has a propeller on the outside, while the rotor and stator integrated with the propeller are located inside the propeller. Because of these features, these motors are referred to as "in-propeller motor". The propulsion system of these motor groups is referred to as "in-propeller motor drive system". All stators are mounted on a non-rotating, hollow axis shaft. The rotors are integrated with coaxial propeller blades.

Description

IN-LINE, IN-PROPELLER COAXIAL ELECTRIC MOTOR GROUP AND DRIVE SYSTEM FOR AIRCRAFTS

TECHNICAL FIELD

The invention relates to motor groups consisting of electric motors for use in electric aircraft and the propulsion system that propels and manages them. The propeller is located at the outermost part of each electric motor. The rotor and stator integrated with the propeller are located inside the propeller. Motor groups are formed by coaxially positioning a plurality of impeller motors on a non-rotating hollow axial shaft. Since the appearance of the motor group resembles a palm-leaf with its one-piece (compact) structure and propellers, the abbreviation "palm motor" is used in the patent text, and the abbreviation "palmkopter" is used for aircraft containing these palm motor.

PRIOR ART

Counter-rotating propeller pair has been used in some aircraft for a long time. These designs include two propellers arranged coaxially one behind the other and rotating in the opposite direction (one clockwise and the other counter-clockwise). It has been designed to obtain high engine power, especially in propeller aircraft. The patent for the counter-rotating twin propeller was taken in the early 1900s, and since then, many global companies have developed and used such engines in aircraft. Today, this technological design is still used in aircraft such as Tupolev-95 and Antonov-70 due to their high performance.

The counter-rotating propeller pair has also been used in electric aircraft for a long time. The electric motor rotates the two coaxial propellers in opposite directions. New ways are sought over time in order to be able to lift more weight. For this purpose, various configurations like tricopters, quadcopters, hexacopters, and octocopters have been developed. For example, when two motor are used in each arm in opposite directions (one pointing upwards and one pointing downwards), it is possible to obtain 8-motor aircraft that look like quadcopters (4-motor).

When examining the developments in this field, the Mars helicopter comes to mind; the most advanced and well-known application of the counter-rotating twin propeller is the Mars Helicopter “Ingenuity” developed by NASA. "Ingenuity", which has two counter-rotating blades and four landing legs, landed on the planet Mars in 2021 and flew there many times. The team that developed this design was awarded the "Space Research Award" in 2021 . For the next trip to Mars, studies have started in NASA for an aircraft that can lift more payloads than "Ingenuity". The successor of the Ingenuity (1.8 kg) proposed for this purpose was named “Mars Science Helicopter” (approximately 30 kg). It has been announced that this will be a “hexacopter”, a six-electric motor drone. Indeed, a counter-rotating twin-propeller aircraft must have larger diameter propellers and be supported by more electric motors in order to carry more payload. This is why the hexacopter (six-electric motor drone) considered at NASA must have come to the fore.

We propose our invention, the palm-leaf-shaped in-propeller motor system, as an important invention at this point. For example, instead of a "hexacopter" with six- electric motors for the Mars Science Helicopter, an inline coaxial in-propeller motor system with six-electric motors, i.e. , a palm motor may be offered. As a name, we use the term palm helicopter "palmcopter" for this type of helicopter design. Aside from the fact that such a system will not take up much space in the space module on its way to Mars, it will have obvious advantages at first glance; a) It has a single compact motor instead of 6 separate motors, b) It can be driven with a much simpler driver, c) It has the ability to fly with uncomplicated software and fewer stability sensors (perhaps without sensors), d) It is lighter than a “hexacopter” due to its frameless structure, e) Much more space is available in the helicopter cabin for electronic circuits and batteries since electric motors are located inside each propeller.

INDUSTRIAL APPLICATION OF THE INVENTION

It is not mechanically possible to counter-rotate more than two propeller blades together (for example, 4, 6, 8, ...). For this reason, the number of blades rotating in opposite directions on the co-axis has not been more than two for years. In the inpropeller motor configuration of our invention, the number of counter-rotating propeller pairs can be increased as desired without any problem in their mechanical design since each propeller has its own motor. The fact that the number of counterrotating propeller pairs can be modularly increased for individuals or aircraft as desired will bring in new and many advantages.

Advantages of our invention; a) Powerful motor groups can be created as desired by increasing the number of propeller pairs since it is possible to obtain greater power with counter-rotating propeller pairs of the same diameter. b) The rotational speed of each individual propeller can be easily adjusted until the optimum rotational speed is achieved. c) The rotational speeds of all propellers can be individually optimized so as to maximize propulsion efficiency since the helical flow of each propeller is corrected by the counter-rotating propeller following it. d) Wide heliports/runways are required for vertical take-off helicopter-like aircraft due to their single and large diameter propellers. In the case of using a palm motor with small-diameter propellers, much smaller areas may be sufficient for take-off and landing. e) The rotational speeds and directions of all propellers can be changed and updated simultaneously according to the weather, temperature, humidity, precipitation, and wind speed and direction, with the help of special software according to the data coming from the “avionics” sensors. f) The overturning torque that will occur at the first take-off, especially for very powerful single-propeller engines, is prevented by counter-rotating propellers. g) It will be easier to design and simpler to manufacture them, and their maintenance cost will be much lower. h) Energy consumption will be much lower since there is no energy loss due to friction due to the use of "Direct Drive" technology. i) High technologies will not be required in their production since it does not contain complex, heavy, and sensitive parts. j) It will be lighter than its counterparts since it does not contain complex, heavy, and fragile parts such as gearboxes, reducers, shafts, etc. As it is known, the light weight of the engines is an important advantage for aircraft. k) The desired number of counter-rotating propeller pairs can be designed in a modular manner.

I) The motor groups will work quite silently and will not cause noise pollution since the propellers are not allowed to have high (supersonic) rotational speeds and rotate in an aerodynamic bearing, also because the electric motors operate silently. m) There will be no need for a cooling unit since the heat that will arise during operation will be cooled by means of the created air currents. n) Using clean and renewable energy, i.e., “zero emission” will be one of its most important advantages.

In summary, our invention, which is the coaxial, in-propeller in-line motor group will have superior features such as having

• the desired power with its modular design using direct drive technology,

• high efficiency,

• lower production and maintenance costs,

• lighter weight,

• lower energy consumption,

• longer battery life,

• longer warranty periods, and

• capable of landing and taking off in small areas,

• using renewable energy,

• being quiet and sensitive to the environment.

If we give some examples that will not limit the scope of protection of our invention;

Advantages in electric aircraft: The in-propeller motor propulsion system can be applied to all types of small, medium and large segment electric aircraft. It can be positioned horizontally on both left and right sides of the wings and/or fuselage of the aircraft. In addition, they can be mounted horizontally on the nose or tail side. Due to the small diameter of the engines and the fact that they are arranged in a row, the aircraft is less exposed to the air resistance that occurs when traveling at high speed. Their low air resistance together with their high torque values ensure them to have a significant advantage over their counterparts.

Advantages in drone-type aircraft: Axial flux motor groups are preferably positioned vertically in drone-type aircraft. This is a very suitable design for manned or unmanned aerial vehicles. Because, currently only one motor is used in each arm of such vehicles. In order to increase the power of the motors, the diameter of the propeller must also be increased. This situation causes serious technical difficulties in the design of drone-type vehicles. In addition, very wide heliports/runways are required for drone-type manned aircraft to take off and land in the city. In our invention, in-line motor groups with the desired power can be used one on top of the other with the same diameter propellers. Therefore, large areas are not required for vehicles to get on and off. In addition, by increasing the number of motors, it can carry much heavier weights than its counterparts. It will be an indispensable part of cargo transportation by virtue of this feature.

Advantages in electric helicopters: The in-propeller motor propulsion system is vertically coupled to vertical take-off helicopter-like aircraft from a single point from the top. The coupling point is determined by considering the center of gravity of the vehicle. Some of the motors that make up the group rotate clockwise and the others counter clockwise. In this case, since a stable equilibrium situation occurs, it allows designs to be made without the need for a tail propeller or even the tail itself. In addition, there is no need for wide helipads as the wing widths will not go beyond the projection of the vehicle. Our invention constitutes an important milestone on the path of urban electric air transportation solutions.

Flying car: The in-propeller motor propulsion system, being able to be vertically connected to vertical take-off helicopter-like vehicles from a single point from the top, is a very important step for humanity to realize the dream of a flying car. It can be easily mounted on any car from the top since there is no need for a tail and tail propeller. Thus, the dream of the drivers to run their propellers and fly when the traffic jams while driving on the highways, and to return to the highway after a while, is realized. From this point of view, the invention makes it possible to transform all land vehicles into flying land vehicles (flying taxi, flying minibus, flying bus, flying caravan, flying tricycle, flying motorcycle, etc.). Such vehicles can easily use any open parking lot in the city for landing and take-off and can park among the cars parked there.

Flying cargo vehicles: Fast and safe cargo transportation has gained importance with the widespread use of online shopping. Vertical take-off and landing aircraft with an in-propeller motor propulsion system will enable flying cargo vehicles to undertake important functions in cargo transportation of different sizes in the future. Flying marine vehicles: Vertical take-off and landing feature, with an inpropeller motor propulsion system, can also be applied to marine vehicles; Inpropeller motor propulsion systems can be used for many different purposes in flying fire extinguishers, flying marine lifeboats, seaplanes, and similar marine vehicles.

Flying armchair: The invention allows the use of the vertical in-propeller motor drive system, which is designed as a flying chair, a flying chair, or a backpack for personal or sports purposes. For example, the invention makes safe flight apparatuses possible where people using it can take off from wherever they want without climbing to a high place and go and land wherever they want like a paraglider.

Flying robots: Humanoid robots, robot mules or robot dogs developed for civil or military purposes are rapidly entering our lives. Thanks to the invention, the ability to fly when necessary is added to the ability of these robots to walk on all kinds of rough surfaces, thereby expanding their usage area further. Flying humanoid robot, flying robot mule or flying robot dog designs become possible by using the vertical inpropeller motor propulsion system. Thus, when the robot encounters an obstacle that it cannot overcome, it will be able to go over the obstacle by taking off vertically from where it stands. This feature expands the usage areas of the tools in the prior art further and makes them unique.

Flying military vehicles: Also in military areas, armed or unarmed, manned or unmanned aerial vehicles, and vehicles carrying weapons or ammunition have superior mobility and freedom of design thanks to the in-propeller motor propulsion system .

Flying toys: The interest of children, especially adolescents, in flying toys has been known for a long time. Toy helicopters, model airplanes, different kinds of drones, flying fairies, princesses, flying geese and even flying toy dinosaurs are available even now. Today, simple motors of varying power and size are widely sold in hobby shops. Now, hobby motors have become a separate sector on their own. Model aircraft motors, propeller, driver, remote control apparatus, mounting parts and battery are sold together as a set. In this sector, mini motor groups in hobby sizes will take their place where in-propeller motor propulsion system is used.

It is extremely important to provide a stable and safe driving comfort in such aircraft. The smooth torque transmission and excellent manoeuvrability of the inpropeller motor propulsion system, which is our invention, can be easily integrated with avionics systems and flight control electronics through balance, speed, direction, pressure, and similar sensors.

As the engine power of a moving aircraft is increased, the diameter of the engines also increases, and accordingly, the air resistance that arises while moving in the air stream increases proportionally. The air resistance of the in-line motor groups of our invention in motion is much less. Because the diameters and propeller diameters of in-line motor groups are much smaller than their counterparts. The air resistance will accordingly be much less. In this respect, our invention can reduce air pollution and traffic congestion in large cities and enable inexpensive, zero-emission transportation in the future.

This system mainly consists of eleven separate components;

• Radial flux or axial flux in-line electric motors

• Rotor and stator arrays positioned inside the propeller

• Impeller with permanent magnet pole pairs integrated with the rotor

• Fixed and rotating elements of the aerodynamic bearing containing air channels

• Hollow axis shaft on which motor stators and rotors are mounted in series one after the other

• Compressor providing high air pressure

• Driver circuit

• Microprocessor

• Special software

• Avionics sensors

• Battery

BRIEF DESCRIPTION OF THE INVENTION

The invention relates to coaxial electric motor assemblies for use in electric aircraft and the propulsion system that manages them. This assembly, consisting of a large number of stators and rotors in series, is arranged on a common, hollow and non-rotating axis shaft. There is a space between the stators and rotors that allows rotation. All stators are fixed to this axis shaft at certain intervals, while rotors are not fixed. All rotors are integrated with the propeller blades and rotate in a ball bearing or aerodynamic bearing without contact. The rotors and stators of each motor are inside its propeller. The power cables and sensor cables of the electric motors pass through the hollow axis shaft and reach the driver and microprocessor. Since there is no casing outside of these motors, air easily enters between the motor parts, cools the heated parts, and therefore there is no need for a cooling apparatus. Electric motors show axial flux or radial flux, DC or AC, single or polyphase, brushless, synchronous or asynchronous winding characteristics.

LIST OF FIGURES

Figure 1a. Application in Drone Type Aircraft

Figure 1b. Application in Helicopter Type Aircraft

Figure 1c. In-Propeller motor Application in Aircraft

Figure 1d. Flying Car Application

Figure 2. Palm-Leaf-Like Appearance

Figure 3. Cross Section of Radial Flux Motor

Figure 4. Cross Section of Axial Flux Motor

Figure 5. Detail View of Rotor of Radial Flux Motor

Figure 6. Detail View of Stator of Radial Flux Motor

Figure 7. Detail View of Rotor of Axial Flux Motor

Figure 8. Detail View of Stator of Axial Flux Motor

Figure 9. Integrated View of Rotor/Propeller of Axial Flux Motor

Figure 10. Integrated View of Rotor/Propeller of Radial Flux Motor

Figure 11. View of Mars Helicopter “Ingenuity”

Figure 12. Palm-Leaf Resembling Helicopter: “Palmcopter”

Figure 13. View of Aerodynamic Bearing Air Channels

The corresponding part numbers in the figures are given below.

1. Electric Motor

1.1. Stator

1.2. Rotor

1.3. Propeller

1 .4. Axial Shaft

1.5. Aerodynam ic Bearing

1 .6. Permanent Magnet Bar

1 .7. Ball Bearing 2. Motor Connection Cables

3. Power Unit

3.1 . Microprocessor

3.2. Motor Driver Circuit

3.3. Software

3.4. Driver Algorithm

3.5. Battery

3.6. Compressor

DETAILED DESCRIPTION OF THE INVENTION

The invention consists of three main parts, i.e. , at least two electric motors (1), motor connection unit (2) and power unit (3). Electric motors (1 ), which is the first part, consist of stator (1.1 ), rotor (1.2), propeller (1.3), profile axis (1.4), aerodynamic bearing (1.5), permanent magnet bar (1.6), and ball bearing (1.7). The motor connection unit (2), which is the second part, contains the connection apparatus (2.1 ) and connection cables (2.2). The power unit (3), which is the third part, consists of the microprocessor (3.1 ), motor driver circuit (3.2), software (3.3), driver algorithm

(3.4), battery (3.5), and compressor (3.6).

The invention consists of in-line stators (1.1 ) and rotors (1.2) positioned on a hollow profile axis (1 .4). There are permanent magnet bars (1 .6) in the rotors (1 .2) of the in-propeller motors to form at least two magnetic poles. The shape and number of these permanent magnet bars (1.6) vary in accordance with the selected motor winding type. The number of blades in the propellers of each of the electric motors (1 ) is at least two or in the form of a single helical blade. Parameters such as the number of blades, blade lengths, and attack angles of the blades are similar to each other but may have different values for each electric motor (1 ). The stator (1.1 ) consists of lamination prepared from iron-silicium alloy or similar materials. In addition, non-iron (ironless) axial flux motors are also preferred because they are light in forming motor groups. The stators (1.1) contain copper wire windings.

In-propeller electric motors (1 ) form motor groups by assembling at least two of them in a row on a linear hollow support profile axis (1.4) with round pipe or polygonal cross-section (triangular, rectangular, square, pentagonal and similar). The stators (1.1 ) of the electric motors (1 ) are fixed from their centres to the profile axis

(1.4). Rotors (1.2), on the other hand, are mounted to rotate in at least one of the magnetic bearings formed by the ball bearing (1.7), aerodynamic bearing (1.5) and permanent magnet bar (1.6). Thus, when electricity is supplied, the stators (1.1) remain stationary and the rotors (1.2) rotate. The electrical power connection cables

(2.2) of each stator (1.1 ) enter the empty space inside the profile through the hole suitable for the support profile axis (1.4), and reach the motor driver circuit (3.2) by advancing separately inside the profile. Each electric motor (1) can be driven together or separately. When the aerodynamic bearing (1.5) and magnetic bearings formed by permanent magnet bar (1.6) are used in the bearing of the propellers integrated with the rotors (1.2), the rotors (1.2) and the stators (1.1 ) rotate without contacting each other. There is a rigid part of the aerodynamic bearing (1.5) between the two stators (1.1 ). This part is made of a composite material such as carbon, teflon, ceramic, or a metal or alloy suitable for bearing such as bronze, and there are many radial air channels on it. On the other hand, there are radial air channels also on the aerodynamic bearing (1.5) surfaces of the propellers. One end of the support profile axis (1.4) on which the electric motors (1) are fixed is closed. Compressed air is supplied from the other end of the support profile axis (1.4) by at least one compressor (3.6). Thus, the compressed air forms an air cushion between the rotors

(1.2) and the stators (1.1 ). While the propeller rotates in the aerodynamic bearing (1.5), the electromagnetic flux formed in the stator (1.1 ) pulls the rotor (1.2) into the stator (1.1 ). Thus, the propellers rotate stably and in balance on the airbags.

Motor groups can be mounted on the front, rear, top, bottom or both sides of the aircraft, in horizontal or vertical position, from one, two or more points, and contain connection apparatuses (2.1 ) in the motor connection unit (2) prepared for this purpose.

There is an alarm system that activates and gives a warning in case of jamming, failure, or breakdown of any electric motor (1 ) among the motor groups. The location of the fault is shown on the screen to the operator.

For safety, there are protection grilles or protection cages around the motor groups.

The driving of the motors is provided with the help of the driver algorithm (3.4) in the software (3.3) on the motor driver circuit (3.2). The windings in the stator (1.1 ) are controlled by the driver algorithm (3.4) in the software (3.3) on the motor driver circuit (3.2) and the magnetic flux generated rotates the rotor (1.2) and the impeller integrated with the rotor (1.2). The rotation directions and rotational speeds for each of the many in-propeller electric motors (1) in the system are determined by the driver algorithm (3.4) in the software (3.3) on the motor driver circuit (3.2) and the ideal torque values are applied simultaneously. The rotation direction (clockwise or counter clockwise) and rotational speed (revolutions/m inute) of the propeller of each of the inpropeller electric motors (1 ) can be determined independently of each other. Each of the electric motors (1) in the motor groups operate individually or together in different rotational modulations determined by special algorithms programmed in the driver algorithm (3.4) in the software (3.3) and by CFD analysis.

The choice of battery (3.5) varies depending on the type of electric motor (1 ) to be used and the winding technique. The type and power of the battery (3.5) also varies according to the total energy consumption of the electric motors (1 ) and the type and range of the aircraft.

Claims

1. It is a motor drive system for electric aircraft and is characterized by containing;

- At least two in-propeller electric motors (1 ),

- Impeller (1.3) integrated with the rotor (1 .2)

- Microprocessors (3.1 ) that allow the rotation direction and rotational speed of the propeller (1.3) of each of the electric motors (1) to be determined independently of each other,

- Motor driver circuit (3.2),

- Custom software (3.3),

- Driver algorithm (3.4),

- Compressor (3.6)

- Hollow axis shaft (1 .4)

- Aerodynamic bearing (1 .5) and

- Ball bearing (1 .7).

2. It is the in-propeller electric motor (1) mentioned in Claim 1 , and it is characterized by the rotor (1.2) and the stator (1.1 ) being located in the inner part, and the propeller (1.3) being located in the outermost part, so that the motor (1 ) being located inside the propeller (1 .3).

3. It is the rotor (1.2) mentioned in Claim 2, and it is characterized by being integrated with the propeller (1.3) and being one piece, containing permanent magnet bars (1 .6) that form magnetic pole pairs.

4. It is the hollow axis shaft (1.4) mentioned in Claim 1 , and it is characterized by being linear and by sequential mounting of stator (1.1 ), rotor (1.2), ball bearing (1 .7) and aerodynamic bearing (1 .5) of at least two in-propeller motors on it.

5. It is the impeller (1.3) integrated with the rotor (1.2) mentioned in Claim 1 , and it is characterized by the number of blades in each propeller (1.3) being at least two or containing a single helical blade.

6. It is the software (3.3) mentioned in Claim 1 , and it is characterized by containing driver algorithms (3.4) that enable each of the electric motors (1) to operate individually or together, with programmed special algorithms, and at different rotational modulations.