Electric aircraft power device adopting contra-rotating double-rotor motor

Abstract

The invention discloses an electric aircraft power device adopting a contra-rotating double-rotor motor. The electric aircraft power device comprises the contra-rotating double-rotor motor, a motor controller, a first propeller, a second propeller, an attack angle fine adjustment system and a slip ring mechanism, the first propeller and the second propeller are installed on the contra-rotating type double-rotor motor, and the contra-rotating type double-rotor motor is connected with the motor controller through the sliding ring mechanism. The attack angles and the rotation directions of the first propeller and the second propeller are opposite, and an attack angle fine adjustment system is arranged at the root of at least one group of propellers and is used for adjusting the attack angles of the propellers, so that the two groups of propellers have the same rotation speed to the ground. Compared with a single-shaft output motor, the power density of the power device is doubled, and the power device is particularly suitable for electric aircrafts with strict requirements for weight.

Description

Technical Field

[0001] The invention belongs to the technical field of electric aviation power, and particularly relates to an electric aircraft power device adopting a contra-rotating dual-rotor motor. Background Art

[0002] Lightweight, high-power density motors are the main driving power sources for future new energy aircraft. Whether it is small and micro four-axis drones or eVTOLs and medium and large electric aircraft, it is the motor that drives the propeller to provide driving force for the aircraft. In order to increase the flight range and payload, the drive motors used in electric aircraft must have a high power density. Limited by materials and cooling conditions, the rated torque that can be output per unit volume of the motor is limited. The main way to increase the power density is to increase the output speed. However, there are some serious problems in using too high an output speed. First, a high-speed motor means a high rotor speed, and too high a speed requires the parts on the rotor to withstand higher centrifugal forces, which poses high requirements on the rotor structure and materials. Second, limited by the fact that the tip speed of the propeller cannot exceed the speed of sound, too high a speed can only be used for propellers with a very small turning diameter, reducing the efficiency of the propeller. Third, too high a propeller speed will generate a lot of noise. To overcome the problems caused by too high a speed, one method is to reinforce the motor rotor with carbon fiber to prevent it from falling apart during high-speed rotation; the second method is to install a high-speed planetary gear reduction box in front of the motor output shaft to reduce the high output speed to an appropriate level; the third method is to reduce the speed through a gear set and distribute it to the output of two mutually reverse rotating shafts; in order to effectively utilize the powerful output power of its engine, the Soviet T-95 strategic bomber adopted a contra-rotating propeller, and through a gearbox, the powerful shaft power of the engine output shaft was distributed to two mutually reverse rotating propellers. Although the shaft speed of a high-speed motor can be reduced by mechanical reduction through a gear set to meet the usage requirements and achieve the purpose of increasing the power density, this method is used more in electric vehicles, but using it on an aircraft will pose a significant challenge, especially for a highly reliable planetary gear reducer. It has long been known that using a contra-rotating dual-rotor motor can eliminate a set of contra-rotating mechanisms composed of gears, and when both contra-rotating shafts are operating at the same rated rotational speed relative to the ground, the power of the motor can be doubled, which is very advantageous for a lightweight motor used to drive an electric aircraft. However, since there is no mechanical constraint between the two output shafts of the contra-rotating dual-rotor motor, the rotational speed of each shaft is not controlled, and there are significant problems when the contra-rotating dual-rotor motor is specifically applied to an aircraft. The rotational speed of each shaft of the contra-rotating dual-rotor motor depends on the output torque of each shaft and the resistance torque it receives. Ignoring the air resistance and bearing friction resistance received when the motor rotor rotates, the torque directions of the two rotors are opposite but the torque values are equal. However, since the resistance torque borne by each propeller is related to various factors such as wind speed, gas density, and its own rotational speed, especially the latter set of two sets of propellers arranged front and back is also affected by the operation of the former set. Assuming the rotational speeds of the two shafts are n1 and n2 respectively, that is, the resistance torque received by the first set of propellers at a rotational speed of n1 is T1, and the resistance torque received by the second set of propellers at a rotational speed of n2 is T2, │T1│ = │T2│.Even if the length, angle of attack, or number of blades of the propellers are adjusted on the ground through tests to make the rated ground rotation speed rates of the two sets of propellers the same, it is still very difficult for the two sets of propellers to maintain similar ground rotation speed rates all the time due to changes in specific working conditions during actual operation. Therefore, to be widely applied as the power source for coaxial contra-rotating propellers in electric aircraft, the current contra-rotating dual-rotor motors must solve the above problems. Documents such as CN 109823519 A provide some pitch-changing mechanisms for coaxial contra-rotating propellers, but these pitch-changing schemes are all based on coaxial contra-rotating propellers powered by a single output shaft, and are not suitable for the dual-axis output power of contra-rotating dual-rotor motors. The contra-rotating propellers of the T-95 strategic bomber are equipped with a pitch adjustment function. This setting is only to enable the engine, which basically operates at a constant speed, to make the propellers perform better efficiency under different working conditions of the aircraft, and cannot ensure that the load torques of the two shafts are the same. CN 222097920 U introduces a dual-rotor motor direct-drive coaxial contra-rotating electric ducted fan. Although it can be seen from its drawings that the diameters of the front and rear fans are different, indicating that the inventor has noticed the working condition characteristics of the reverse-rotating fans arranged front and back, no further solutions have been taken. Simply adjusting the fan diameter and the number of fan blades can only solve the basic balance of the front and rear fans under a certain small range of working conditions, and cannot guarantee various working conditions that may be encountered during flight from low altitude to high altitude and from low speed to high speed. Due to the randomness and diversity of actual working conditions, the existing technical solutions for the two sets of propellers driven by contra-rotating dual-rotor motors cannot solve the problem of the same output power of the two rotors under various working conditions. In addition, the rotor containing the armature winding of the contra-rotating dual-rotor motor also rotates during operation, and a slip ring composed of a collector ring and a brush must be used to conduct rotary power feeding to the electrode winding. Ordinary rotary electric slip ring brushes are not very suitable for the high efficiency and lightweight requirements of the power device of an electric aircraft because of their large contact voltage drop, small current density, large operating friction resistance, and large volume and weight. Mercury slip rings have a small contact voltage drop, large current density, small operating friction resistance, and small volume and weight, seemingly very suitable, but due to the toxicity of mercury and the upper working temperature limit of 60°C, it is determined that mercury slip rings cannot be widely used in the field of electric aircraft. Summary of the Invention

[0003] The purpose of the present invention is to provide a power device for an electric aircraft using a contra-rotating dual-rotor motor to solve the problems of rotational speed balance of the two rotors and wear resistance of the slip ring.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions: An electric aircraft power device using a counter-rotating twin-rotor motor comprises the counter-rotating twin-rotor motor, a motor controller, a first propeller, a second propeller, an angle of attack fine-tuning system and a slip ring mechanism; the first propeller and the second propeller are mounted on the counter-rotating twin-rotor motor, and the counter-rotating twin-rotor motor is connected to the motor controller via the slip ring mechanism; the first propeller and the second propeller have opposite angles of attack and opposite directions of rotation, and at least one set of propellers is provided with an angle of attack fine-tuning system at its root for adjusting the angle of attack of the propeller so that the two sets of propellers have the same ground speed rate.

[0005] Furthermore, the counter-rotating dual-rotor motor includes a first rotor, a second rotor, a first rotor output shaft and a second rotor output shaft, the first rotor output shaft is connected to the first rotor, the second rotor output shaft is connected to the second rotor, the second rotor is arranged on the first rotor output shaft through a bearing, the lead wire of the first rotor is connected to the corresponding electrode of the slip ring mechanism, and the first propeller and the second propeller are respectively installed on the first rotor output shaft and the output shaft of the second rotor.

[0006] Furthermore, the angle of attack fine-tuning system includes an angle of attack adjustment mechanism installed at the root of the propeller, a first speed sensor, a second speed sensor, an electric thrust cylinder and an angle of attack control circuit; the first speed sensor and the second speed sensor are both installed on the sides of the first rotor and the second rotor through a fixing seat; the electric thrust cylinder is connected to the angle of attack adjustment mechanism; the angle of attack control circuit subtracts the speeds of the two rotors detected by the speed sensor, amplifies the difference signal and then stimulates the electric thrust cylinder to adjust the angle of attack of the propeller.

[0007] Furthermore, the angle of attack adjustment mechanism includes a bearing and a crank installed at the root of the blade and a telescopic sleeve driven by an electric push cylinder. The telescopic sleeve is provided with a group of inclined grooves at a set angle to the axis. The end of the crank at the root of the blade is inserted into the inclined groove of the telescopic sleeve. When the sleeve is pushed back and forth by the push rod of the electric push cylinder, the inclined groove will drive the crank to change the angle of attack of the blade.

[0008] Furthermore, the slip ring mechanism includes a slip ring including an inner rotating body, an outer rotating body, a low melting point alloy and a constant temperature heater, a bearing is arranged between the inner rotating body and the outer rotating body, the inner rotating body is fixedly sleeved on the shaft and fixedly connected to the first rotor, the constant temperature heater is embedded on the outer rotating body, and a low melting point alloy is arranged between the inner rotating body and the outer rotating body. When the constant temperature heater is working, the low melting point alloy melts, and the inner rotating body and the outer rotating body can rotate relative to each other.

[0009] Further, the inner rotating body includes an inner shaft sleeve, an insulating member, and a conductive disk. The insulating member is sleeved on the inner shaft sleeve, and the inner shaft sleeve is sleeved on the shaft. Several circles of conductive disks are arranged on the outer side of the insulating member; the outer rotating body includes an insulating member, a slip ring, and an outer lead wire. A slip ring matching the conductive disk is arranged on the inner side of the insulating member of the outer rotating body. The conductive disk is arranged inside the slip ring, and the low-melting-point alloy is arranged between the conductive disk and the slip ring; the slip ring is a circular ring with a V-shaped groove in cross section, and the low-melting-point alloy is arranged in the V-shaped groove; an air passage is arranged on the insulating member of the outer rotating body for introducing inert gas between the conductive disk and the slip ring; the constant-temperature heater includes a temperature switch and a heating wire, and the heating wire is connected to the temperature switch.

[0010] Further, the conductive disk is a flat circular ring-shaped assembly welded by a plurality of sector-shaped petals that can extend into the V-shaped groove of the slip ring and a bus ring, and its outer side is thinner and the cross section is spiky; a liquid retaining ring is arranged on the conductive disk.

[0011] Further, the gap between the inner rotating body and the outer rotating body is of a labyrinth type. A sealing disk is arranged at the open end of the inner rotating body. A ring-shaped sealing groove with a V-shaped cross section is arranged at the corresponding position of the outer rotating body and is provided with sealing grease therein, or a magnet ring with axial magnetization is arranged at the open end of the inner rotating body. Two liquid storage grooves are opened at the corresponding parts of the outer rotating body for storing magnetic fluid made of low-volatility liquid and micro-nano soft magnetic powder.

[0012] An electric aircraft power device of a ducted contra-rotating dual-rotor motor includes the above-mentioned electric aircraft power device of a contra-rotating dual-rotor motor, including a front support rod, a rear support rod, a duct cylinder body, and a central shaft. A front support rod and a rear support rod are respectively arranged at the front and rear in the duct cylinder body to jointly support a non-rotating central shaft. The first rotor and the second rotor are respectively arranged on the outer side of the central shaft through bearings on their inner sides and can rotate around the central shaft. A first fan and a second fan are respectively arranged on the first rotor and the second rotor. The attack angle directions of the two groups of fans are opposite, and at least one group of fans is provided with an attack angle adjustment system; the attack angle fine adjustment system includes an attack angle adjustment mechanism installed at the root of the fan, a first speed sensor and a second speed sensor installed on a fixed seat near the first rotor and the second rotor, an electric push cylinder, and an attack angle control circuit. The attack angle control circuit subtracts the speeds of the two rotors detected by the speed sensors, and after amplifying the difference signal, adjusts the attack angle of one group of propellers.

[0013] Further, the attack angle adjustment mechanism includes a bevel gear, an adjustment ring, a servo motor, and a slip ring at the root of the fan. The right side of the adjustment ring is the main gear, the left side of the adjustment ring is the sub-gear, and the inner side of the adjustment ring is arranged on the second rotor shaft through a bearing. The bevel gear on the output shaft of the servo motor meshes with the sub-gear of the adjustment ring, and the main gear of the adjustment ring meshes with the bevel gear; the base of the servo motor is fixedly connected to the second motor shaft.

[0014] Furthermore, the counter-rotating dual-rotor motor has a central through-shaft fixed structure, which is axially connected and integrated by multiple axial magnetic ventilation gap motor units. The number of armature rotor units is ≥2, and the number of working air gaps is ≥4.

[0015] Compared with the prior art, the present invention has the following technical effects: The angle of attack adjustment mechanism of the electric aircraft power device using a counter-rotating dual-rotor motor in the present invention detects the ground speeds of the two rotors using a rotational speed sensor and adjusts the angle of attack of one set of propellers or fans according to the difference in rotational speeds to make the rotational speeds of the two rotors the same, so that the output powers of the two rotors are the same, avoiding the situation of one shaft stalling and freezing caused by too large a speed difference. The counter-rotating dual-rotor motor of the present invention doubles the power at the same rotational speed compared with a single-shaft output motor with the same volume electromagnetic main body having the same ground speed, and is particularly suitable as the power for an electric aircraft sensitive to weight.

[0016] The present invention uses a low-melting-point metal of a room-temperature-based solid as the liquid brush working medium, which is pollution-free. The molten metal liquid is difficult to be oxidized under the protection of an inert gas. The extremely low contact voltage drop and large contact area make the liquid metal brush slip ring of the present invention small in volume, light in weight, high-speed and long-life, so that the counter-rotating dual-rotor motor is lighter in weight and larger in power density, and is particularly suitable as the power for an electric aircraft sensitive to weight. Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the basic structural composition of the power device of the present invention.

[0018] Figure 2 It is a schematic diagram of the basic structural composition of the ducted power device of the present invention.

[0019] Figure 3 It is a partial schematic diagram of the gear-type fan blade angle of attack adjustment mechanism of the present invention.

[0020] Figure 4 It is a partial schematic diagram of the crank-type fan blade angle of attack adjustment mechanism of the present invention.

[0021] Figure 5 It is a schematic diagram of the armature external connection commutator type double air-gap brushless motor structure of the present invention.

[0022] Figure 6 It is a schematic diagram of the armature internal connection commutator type double air-gap brushless motor structure of the present invention.

[0023] Figure 7 It is a block diagram of the control system of the present invention.

[0024] Figure 8It is a partial schematic diagram of the non-rotating crank angle-of-attack adjustment mechanism of the electric push cylinder of the present invention.

[0025] Figure 9 It is a schematic diagram of the liquid metal slip ring of the present invention.

[0026] Figure 10 It is a schematic diagram of the coaxial contra-rotating propeller dual-rotor motor using the liquid metal slip ring of the present invention.

[0027] Figure 11 It is a schematic diagram of the coaxial contra-rotating propeller dual-rotor axial magnetic field motor using the liquid metal slip ring.

[0028] Figure 12 It is a partial enlarged schematic diagram of the liquid metal slip ring of the present invention.

[0029] Figure 13 It is a schematic diagram of the heater of the liquid metal slip ring of the present invention.

[0030] Figure 14 It is a schematic diagram of the conductive disk of the liquid metal slip ring with a liquid retaining ring of the present invention.

[0031] Figure 15 It is a schematic diagram of the liquid metal slip ring containing a magnetic liquid seal ring of the present invention.

[0032] Figure 16 It is a schematic diagram of the liquid storage net of the liquid metal slip ring of the present invention.

[0033] Figure 17 It is a schematic diagram of the multi-air-gap axial-flux contra-rotating dual-rotor motor of the present invention.

[0034] Wherein: 1 - first rotor, 2 - second rotor, 3 - first rotor shaft, 4 - second rotor shaft, 5 - mounting base, 6 - conductive slip ring, 7 - second rotor speed sensor, 8 - first rotor speed sensor, 9 - sensor support, 10 - bearing, 11 - bearing, 12 - first propeller, 13 - second propeller, 14 - motor lead wire, 15 - servo motor lead wire, 16 - servo motor, 17 - propeller hub, 18 - crank, 19 - inclined slot, 20 - slider, 21 - bevel gear, 22 - adjusting ring, 23 - bevel gear, 24 - slip ring, 25 - front support rod, 26 - rear support rod, 27 - first fan, 28 - second fan, 29 - duct cylinder, 30 - fixed shaft, 31 - front fairing cone, 32 - rear fairing cone, 35 - electric push cylinder, 36 - push rod, 37 - bearing, 38 - angle-changing disc, 39 - fan shaft, 40 - crank, 41 - arc-section inclined slot, 42 - ball head, 50 - first single-chip microcomputer, 51 - bridge-type PWM driver, 52 - motor, 53 - first rotor, 54 - second rotor, 55 - second sensor, 56 - first sensor, 57 - second single-chip microcomputer, 58 - bridge-type PWM driver, 59 - angle-of-attack servo motor, 60 - (blank), 61 - first air gap, 62 - second air gap, 63 - armature core, 64 - armature winding, 65 - permanent magnet, 66 - armature retaining ring, 67 - key, 68 - expansion ring, 69 - bearing, 71 - reinforcing ring, 72 - armature seat, 73 - yoke iron ring, 74 - shaft, 75 - fairing, 76 - telescopic rod, 77 - spline sleeve, 81 - inner rotating body, 82 - outer rotating body, 83 - ventilation duct, 84 - bushing, 85 - collector ring, 86 - conductive disc, 87 - liquid metal, 88 - pipe joint, 89 - bearing, 90 - liquid retaining ring, 91 - inner lead wire, 92 - outer lead wire, 93 - welding point, 94 - welding point, 95 - mounting screw hole, 96 - heating wire, 97 - end cover, 99 - yoke iron, 100 - key, 101 - heater lead wire, 102 - temperature switch, 103 - sealing groove, 104 - sealing disc, 105 - insulating member, 106 - magnetic ring, 107 - liquid storage tank, 108 - magnetic fluid, 109 - storage net, 110 - insulating member, 112 - hollow shaft, 121 - sealing grease, 122 - heating wire, 123 - pressing plate, 124 - end cover, 125 - molded support. Detailed implementation manners

[0035] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] In the description of the present invention, it should be noted that terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. In addition, terms such as "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, terms such as "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0038] Embodiment 1 Please refer to Figure 1 、 Figures 5 to 7 、 Figure 17, A power plant for a coaxial contra-rotating propeller electric aircraft driven by a contra-rotating dual-rotor motor, comprising a contra-rotating dual-rotor motor, a motor controller, a first propeller 12, a second propeller 13, and an angle of attack fine-tuning mechanism. The contra-rotating dual-rotor motor includes a first rotor 1, a second rotor 2, a first rotor output shaft 3, a second rotor output shaft 4, a conductive slip ring 6, a fixed seat 5, bearings, and fasteners. The power input terminal of the motor controller is connected to the aircraft power supply, the speed control terminal is connected to the aircraft flight control system, and the output terminal is connected to the input terminal on the motor conductive slip ring. The first propeller 12 and the second propeller 13 are respectively installed at the ends of the first rotor output shaft 3 and the second rotor output shaft 4. At least one group of propellers has an angle of attack adjustment mechanism. The angle of attack adjustment system includes an angle of attack adjustment mechanism and a second speed sensor 7, a first speed sensor 8, an angle of attack electric cylinder 79, and an angle of attack control circuit installed on non-rotating supports near the two rotors. The angle of attack adjustment mechanism includes a bearing and a crank 18 installed at the root of the blade and a telescopic sleeve 20 driven by an electric cylinder 35. A set of inclined slots 19 at a certain angle to the axis is provided on the telescopic sleeve 20. The spherical surface at the end of the crank 18 at the root of the blade is inserted into the inclined slot 19 outside the sleeve 20. The inclined slot 19 forms an acute angle with the axis direction. When the telescopic sleeve 20 is pushed back and forth by the push rod of the electric cylinder 35, the inclined slot 19 will drive the crank to change the angle of attack of the blade. The angle of attack adjustment mechanism can also use a crank pull rod or other common structural forms. The second speed sensor 7 and the first speed sensor 8 are respectively used to detect the rotational speed of the first rotor 1 and the second rotor 2 relative to the fixed seat 5. The angle of attack control circuit controls the servo motor to adjust the angle of attack of the propeller according to the difference in the rotational speeds measured by the two rotor speed sensors so that the rotational speeds of the two rotors are the same. The speed sensor can be an optoelectronic type, an electromagnetic induction type, or a Hall switch. The motor controller and the angle of attack control circuit are generally installed independently on the base of the aircraft, or the two can be integrated together. When the controller of the dual-rotor motor can provide the working frequency signal of the armature, the angle of attack adjustment system can only use the second speed sensor 7. For synchronous motors and self-synchronous motors, the relative rotational speed of the two rotors is equal to the quotient of the fundamental frequency output frequency of a certain phase inside the motor controller and the number of pole pairs of the motor. For asynchronous motors, the relative rotational speed of the two rotors is also approximately equal to the quotient of the fundamental frequency output frequency of a certain phase inside the motor controller and the number of pole pairs of the motor. The rotational speed of the rotor without a speed sensor installed is equal to the difference between the relative rotational speed of the two rotors and the detection speed of the rotor speed sensor. When the motor is working, if the ground speed of the first rotor 1 is greater than the ground speed of the second rotor 2, the angle of attack adjustment system will reduce the angle of attack of the second propeller 13, increase the ground speed of the second rotor 2, and reduce the ground speed of the first rotor 1 until the ground speeds of the two rotors are the same. The disadvantage of this example is that the angle of attack fine-tuning servo motor needs to rotate with the shaft, so the servo motor needs to be powered through a slip ring.To reduce wear and adapt to higher altitudes, the collector rings and brushes of the slip ring can be made of graphite materials with high conductivity and low wear. Since the rated power of the contra-rotating motor is twice that of a conventional motor when both rotors operate at the same rated speed, and due to the use of components such as slip rings, the actual power density can be increased by about 0.8 times. The rear propeller of the coaxial contra-rotating propellers can utilize the eddy currents generated at the tips of the front propeller to generate additional power, and the direct drive of the propeller by the contra-rotating dual-rotor motor saves the loss of mechanical transmission of the gearbox. Therefore, the present invention can improve the overall propulsion efficiency of the electric aircraft. For the power plant of an electric aircraft with coaxial contra-rotating propellers driven by a contra-rotating dual-rotor motor used for low-altitude aircraft limited to flights within several hundred meters, the angle of attack of the two sets of propellers can be made into fixed angles of different angles, eliminating the need for an angle-of-attack fine-tuning mechanism. The specific method is to first determine the angle of attack of one set of propellers through calculation, and then, under the condition that the relative speed of the two rotors is twice the rated speed of a single rotor, by changing the angle of attack of the other set, make the ground speeds of the two sets of fans the same and both reach the rated speed, thereby obtaining the optimal angle of attack of the other set of propellers. This can significantly reduce the complexity of the power plant and also significantly reduce the manufacturing cost. To further improve the power density of the motor, a dual air-gap image can be adopted. Figure 5 , Figure 6 Such a dual air-gap axial flux motor structure. It is also possible to axially stack and integrate multiple axial magnetic flux armature rotor units and multiple permanent magnet rotor units to form a multi-air-gap axial flux motor. The multi-air-gap axial flux motor can obtain a larger torque under a larger length-to-diameter ratio, which is beneficial to improving the power density and is particularly suitable for ensuring the necessary distance between the first propeller and the second propeller angle or the first fan and the second fan to avoid the collision of the front and rear blades. Figure 17 It is a schematic diagram of a 6-air-gap axial flux contra-rotating dual-rotor motor, which axially integrates three armature rotors with through teeth cores and 4 groups of magnet rotors, and can provide a torque 6 times that of a single air-gap axial flux motor with the same radial size. At the same speed, it can provide an output power 6 times that of a single air-gap axial flux motor with the same radial size.

[0039] Embodiment 2 Please refer to Figure 2 , Figure 3 , Figure 7 , Figures 9 to 17. A ducted electric aircraft power plant for a contra-rotating dual-rotor motor with an axial magnetic air gap. The ducted contra-rotating fan propulsion device includes two sets of contra-rotating propellers, their driving motors, and an angle of attack control device. Two sets of radial support columns are respectively arranged at the front and rear of the duct to jointly support a fixed non-rotating central shaft. The two rotors of the motor are respectively arranged on the outside of the central shaft through the bearings on their inner sides and can rotate around the shaft. A set of fans with opposite angles of attack are respectively arranged on the two rotors, and at least one set of fans is provided with an angle of attack adjustment system at the root; the angle of attack adjustment system includes an angle of attack adjustment mechanism arranged at the root of the second fan, a rotor speed sensor, an angle of attack servo motor, and an angle of attack control circuit. The angle of attack adjustment mechanism includes a bevel gear 21, an adjustment ring 22, a servo motor 16, and a slip ring 24 at the root of the fan. The right side of the adjustment ring 22 is the main gear, the left side of the adjustment ring 22 is the sub-gear, and the inner side of the adjustment ring 22 is arranged on the second rotor shaft 4 through a bearing. The bevel gear 23 on the output shaft of the servo motor 16 meshes with the sub-gear of the adjustment ring, and the main gear of the adjustment ring meshes with the bevel gear 21. The base of the servo motor 16 is fixedly connected to the second motor shaft 4. Two speed sensors are respectively used to detect the rotational speeds of the two rotors relative to the duct. The angle of attack control circuit adjusts the angle of attack according to the difference in the rotational speeds measured by the two rotor speed sensors so that the rotational speeds of the two rotors tend to be the same. The second rotor shaft 4 of the second rotor 2 is arranged behind the front support column 25 of the duct, and the first rotor shaft 3 of the first rotor 1 is arranged in front of the rear support column 26 inside the duct. A cable is installed inside the front support column 25 and supplies power to the servo motor 16 installed at the left end of the second rotor 2 through the hole of the central shaft 30 and the slip ring 24. A cable is also provided inside the rear support column 26 and supplies power to the armature winding on the first rotor 1 through the inner hole of the central shaft 30 and the slip ring 6. The dual-rotor motor can be any one of an asynchronous motor, a permanent magnet brushless motor, or an SR motor with a radial air gap magnetic field or an axial air gap magnetic field. For short-life applications, a brush motor structure with a commutator can also be selected. The motor controller can be installed in the front and rear fairing cones inside the duct cylinder 29, or on the outside of the duct cylinder 29, or in the wing or fuselage of the aircraft. The angle of attack control circuit is generally independently installed in the front and rear fairing cones inside the duct cylinder 29, or can be integrated with the motor controller. For medium and large aircraft, due to the large operating current of the motor, if a general solid brush is used for the slip ring, the power loss and heat generation will be large, and the service life and safety will also be reduced. In view of this situation, a liquid brush should be preferably used for the larger power contra-rotating dual-rotor motor. However, usually, mercury is used as the working medium for the liquid brush, which has problems such as a low upper limit of the working temperature and being harmful to the environment. The liquid brush of the liquid brush slip ring assembly described in the present invention uses a low-melting-point alloy material with less corrosion, and is rapidly heated before the motor starts to quickly melt the low-melting-point alloy material.The liquid brush slip ring made of low-melting-point alloy contains a constant-temperature heating device, an inert gas storage tank and a release valve. The working medium of the liquid brush is selected from low-melting-point alloy materials such as tin-bismuth (Sn-Bi) and indium-bismuth-tin (In-Bi-Sn) with good fluidity, low corrosiveness and oxidation resistance. Before and during the operation of the motor, the constant-temperature heating device is turned on to turn the low-melting-point alloy into a highly fluid conductive liquid with ultra-low viscosity. At the same time, the inert gas release valve is opened to fill and supplement the working space of the slip ring with inert gas to prevent the molten metal liquid from oxidizing. After the motor stops running, the constant-temperature heating device and the inert gas release valve are closed. The ducted electric aircraft power plant can eliminate the eddy current generated at the blade tip and improve the propulsion efficiency. For the coaxial contra-rotating ducted fan power plant driven by a contra-rotating dual-rotor motor used in low-altitude aircraft limited to flying within a few hundred meters, the angle of attack of the two groups of fans can be made into fixed angles of different angles, eliminating the need for an angle-of-attack fine-tuning mechanism. The specific method is to first determine the angle of attack of one group of fans through calculation, and then, under the condition that the relative speed of the two rotors is twice the rated speed of a single rotor relative to the ground, by changing the angle of attack of the other group, make the ground speeds of the two groups of fans the same, so as to obtain the optimal angle of attack of the other group. This can significantly reduce the complexity of the power plant and also significantly reduce the manufacturing cost. To further improve the power density of the motor, multiple axial magnetic flux armature rotor units and multiple permanent magnet rotor units can be axially stacked and integrated to form a multi-air-gap axial flux motor. The multi-air-gap axial flux motor can obtain a larger torque under a larger length-diameter ratio, which is beneficial to improving the power density and is particularly suitable for ensuring the necessary distance between the first propeller and the second propeller angle or the first fan and the second fan to avoid collision between the front and rear blades. Figure 17 It is a schematic diagram of a 6-air-gap axial flux contra-rotating dual-rotor motor, which axially serially integrates three armature rotors with through teeth cores and 4 groups of magnet rotors, and can provide a torque 6 times that of a single-air-gap axial flux motor with the same radial size. At the same rotational speed, it can provide an output power 6 times that of a single-air-gap axial flux motor with the same radial size.

[0040] Embodiment 3 Please refer to Figure 4。An angle of attack adjustment mechanism for an electric pusher cylinder of a ducted electric aircraft power plant of a contra-rotating dual-rotor motor with an axial magnetic ventilation gap. On the left side of the second rotor 2, there is a second fan 28 or a second blade 13 with adjustable angle of attack and a fine adjustment mechanism. The fine adjustment mechanism includes a sleeve 38, a crank 40 fixed to the root of the fan, an expansion ring 36, and a bearing 37. There is a set of arc-section inclined grooves 41 on the outside of the sleeve 38 that are inclined at a certain angle to the axis. The ball head 42 at the end of the crank 40 at the root of the fan extends into the arc-section inclined grooves 41. The inner side of the sleeve 38 has an internal spline that is in clearance fit with the external spline on the outside of the second rotor shaft 4 on the left side of the second rotor 2. The right side of the expansion ring 36 is connected to the sleeve 38 through a bearing 37, and the left side of the expansion ring 36 is connected to the end of the push rod of the angle of attack servo electric pusher cylinder 35. When the electric pusher rod expands or contracts, the arc-section inclined grooves 41 will drive the crank 40 at the root of the fan to rotate around the fan shaft, thereby changing the angle of attack of the fan. It is possible to use only one electric pusher rod to pass through the gap of the support rod to push the expansion ring 36, or multiple electric pusher rods arranged in the gap of the support rod can be used to synchronously push the expansion ring 36. In this example, the angle of attack servo electric pusher cylinder does not rotate with the rotor.

[0041] Embodiment 4 Please refer to Figure 5 、 Figure 6 、 Figure 17 For the dual-air-gap contra-rotating motor of the ducted electric aircraft power plant of the present invention, Figure 3 it is a dual-axial air-gap first rotor external connection structure. The first rotor 1 and the second rotor 2 form two magnetic field air gaps, namely the first air gap 61 and the second air gap 62, that generate mutual forces axially. The first rotor 1 is arranged on a fixed shaft through the armature hoop 66 and bearings on its outside. Slip rings are provided beside the two bearings to undertake the electrical connection between the armature winding on the first rotor 1 and the motor controller. The motor uses a sensorless permanent magnet brushless DC motor. At the left end of the second rotor, there is a second fan or a second blade with a fixed angle of attack. At the right side of the first rotor, there is a second fan 28 or a second blade 13 with adjustable angle of attack and a fine adjustment mechanism. The fine adjustment mechanism includes a set of parallel keys 67 arranged on the outer circle of the shaft, an expansion ring 68, a bearing 69, a sleeve 38, and a crank 40 fixed to the root of the fan. The end of the external angle of attack fine adjustment electric pusher rod is connected to the expansion ring 68 and drives the sleeve 38 to move axially back and forth through the bearing 69; there is a set of arc-section inclined grooves 41 on the outside of the sleeve 38 that are inclined at a certain angle to the axis. The ball head 42 at the end of the crank 40 at the root of the fan extends into the arc-section inclined grooves 41. When the angle of attack fine adjustment electric pusher rod expands or contracts, the arc-section inclined grooves 41 will drive the crank 40 at the root of the fan to rotate, thereby changing the angle of attack of the fan. The advantage of the dual-axial air-gap first rotor external connection structure is that it is easy to ensure the mechanical strength of the first rotor with the armature. The armature hoop 66 not only undertakes the fixation of the first rotor 1 but also can bear the strong centrifugal force generated by the first rotor 1 during high-speed rotation. Figure 4It is a double-axial air-gap first rotor external connection structure. The first rotor 1 and the second rotor 2 form two magnetic field air-gaps, namely the first air-gap 61 and the second air-gap 62, that generate interaction forces axially. The first rotor 1 is mounted on a fixed shaft through its inner armature seat 72 and bearings. A slip ring is provided inside the first rotor 1 to undertake the electrical connection between the armature winding on the first rotor 1 and the motor controller. The motor adopts a sensorless permanent magnet brushless DC motor. A second fan 28 or a second blade 13 with a fixed angle of attack is provided at the left end of the second rotor 2. A second fan 28 or a second blade 13 with an angle of attack and a fine-tuning mechanism are provided on the right side of the first rotor 1. The fine-tuning mechanism includes a set of parallel keys 67, an expansion ring 68, a bearing 69, a sleeve 38 arranged on the outer circumference, and a crank 40 fixed to the root of the fan. The end of the fine-tuning electric push rod for the external angle of attack is connected to the expansion ring 68 and drives the sleeve 38 to move axially back and forth through the bearing 69. There is a set of arc-section inclined slots 41 with a certain angle to the axis outside the sleeve 38. The ball head 42 at the end of the crank 40 at the root of the fan extends into the arc-section inclined slots 41. When the fine-tuning electric push rod for the angle of attack expands and contracts, the arc-section inclined slots 41 will drive the crank 40 at the root of the fan to rotate, thereby changing the angle of attack of the fan. The advantage of the first rotor internal connection structure is that a carbon fiber winding reinforcement ring 71 with a relatively mature process can be adopted on the outside of the armature, and high-strength and high-modulus carbon fiber is used for reinforcement to ensure that the first rotor 1 can withstand very high speeds without damage. According to the topology of the contra-rotating double-rotor motor, the double-air-gap motor can also be made into a double-radial air-gap structure, and all the outer circular surfaces of the first rotor 1 and the second rotor 2 are reinforced with carbon fiber. There are also various options for the motor type. For example, asynchronous induction motors, SR motors, and brushless coreless motors can all be used. For short-life aircraft for single use, a permanent magnet DC motor or a series-wound motor with a commutator can also be used. The aim is to make the motor have a large power density. The double-air-gap motor essentially integrates two independent motors into one motor. The area of the double air-gap is doubled compared with the single air-gap, and theoretically the output torque can be doubled. The power of the contra-rotating double-rotor double-air-gap motor is 4 times that of a common single-rotor single-air-gap motor, and the power density is increased by more than 1.5 times. However, the structural complexity and manufacturing process difficulty of the double-air-gap motor are also significantly increased. The double-air-gap motor can be made into a single-armature structure with an armature in the middle and magnetic steel on both sides as in this example, or a double-armature structure with magnetic steel in the middle and armatures on both sides. The advantage of the double-armature structure is that the amount of magnetic steel used is small, the disadvantage is that the amount of copper used is large, and the total weight of the motor increases. In addition to permanent magnet brushless motors, one side of the magnetic steel can also be made into a reluctance rotor or an induction rotor to become a contra-rotating double-rotor double-air-gap SR motor or a contra-rotating double-rotor double-air-gap asynchronous induction motor. In order to further increase the length-diameter ratio of the motor under the condition of a certain rated output torque, multiple axial magnetic flux-carrying armature rotor units and multiple permanent magnet rotor units can also be axially stacked and integrated to form a multi-air-gap axial flux motor.The multi-air-gap axial flux motor can obtain a large torque under the condition of a large length-diameter ratio, which is beneficial to improving the power density, and is especially suitable for ensuring the necessary distance between the first propeller and the second propeller or the first fan and the second fan to avoid the collision of the front and rear blades. Figure 17 It is a schematic diagram of a 6-air-gap axial flux contra-rotating dual-rotor motor, which integrates three armature rotors with through teeth cores and 4 groups of permanent magnet rotors in series axially, and can provide a torque 6 times that of a single-air-gap axial flux motor with the same radial size, and can provide an output power 6 times that of a single-air-gap axial flux motor with the same radial size at the same speed.

[0042] Embodiment 5 Please refer to Figure 7 、 Figure 8, A power plant for a coaxial contra-rotating propeller electric aircraft driven by a contra-rotating dual-rotor motor, comprising a contra-rotating dual-rotor motor, a motor controller, a first propeller 12, a second propeller 13, and an angle of attack fine-tuning system. The basic structure of the motor part is similar to that of Embodiment 1, with the main difference being that the electric push cylinder of the angle of attack fine-tuning system does not rotate. The angle of attack adjustment system includes an angle of attack adjustment mechanism and a rotational speed sensor 8, an electric push cylinder 35, and an angle of attack control circuit installed near the root of the first propeller. The angle of attack adjustment mechanism includes a bearing 69 and a crank 18 installed at the root of the blade, and an adjustment disk 38 driven by the electric push cylinder 35. The inner side of the adjustment disk 38 is connected to the end of the central shaft by a spline. The inner left end of the adjustment disk 38 is fixedly connected to a push rod 76. The outer left end of the adjustment disk 38 is connected to the inner ring of the bearing 69. A set of inclined slots 19 that form a certain angle with the axis in the bus are provided on the adjustment disk 38. The ball head 42 at the end of the crank 18 at the root of the blade is inserted into the inclined slot 19 outside the adjustment disk 38. The inclined slot 19 is horizontally parallel to the axis and longitudinally forms a 5° angle with the axis. When the adjustment disk 38 is pushed by the push rod of the electric telescopic cylinder 35 to move back and forth longitudinally, the inclined slot 19 will drive the crank to change the angle of attack of the blade. During operation, the first single-chip microcomputer sends a control signal to the bridge-type PWM driver 51 according to the control instruction. The bridge-type PWM driver 51 excites the armature winding of the first rotor to generate an interaction between the first rotor and the second rotor to make them rotate in opposite directions. Due to the load characteristics, in this example, a sensorless permanent magnet brushless DC motor that detects the zero crossing of the back electromotive force to sense the voltage is selected for the motor. There are only three connection lines between the motor winding and the motor controller, which are connected through a three-pole slip ring. The rotational speed sensor 8 uses a Hall switch IC to detect the rotational speed n1 of the first rotor 1. The second single-chip microcomputer 57 of the angle of attack control circuit divides the relative rotational speed signal of the rotor sent by the motor controller by 2 to obtain the rotational speed value n when the rotational speeds of the two rotors relative to the ground are the same. The difference between n1 and n is used as a control quantity to modulate the duty cycle of the bridge-type PWM driver 58 to drive the electric push cylinder 35 to move back and forth. The electric push cylinder motor generally selects a permanent magnet brushless DC motor, or a stepper motor can also be selected. The contra-rotating dual-rotor motor can also be made into a double air-gap structure to further improve the power density.

[0043] Embodiment 6 Please refer to Figure 9 , Figure 10 , Figure 15。A coaxial contra-rotating propeller dual-rotor axial magnetic field motor using a liquid metal slip ring, comprising a first rotor 39, a second rotor 19 and a slip ring. The slip ring includes an inner rotating body 81, an outer rotating body 82 and a constant temperature heater. The inner rotating body 81 includes an inner bushing 84, an insulating member 105, a conductive disk and a lead wire. The outer rotating body includes an insulating member 105, a collector ring 85, an outer lead wire 92 and a constant temperature heater embedded in the insulating member 105. The constant temperature heater includes a temperature switch 102 and a heating wire 96. Bearings are provided at both ends between the inner and outer rotating bodies and can rotate relative to each other; the collector ring 85 is a ring with a V-shaped groove in cross section, and a certain amount of low melting point alloy is provided in the groove; before operation, first energize the constant temperature heater to heat the collector ring 85 to melt the low melting point alloy in its V-shaped groove into liquid metal 87, and at the same time open the release valve to introduce inert gas into the inside of the slip ring from an external inert gas storage tank and form a positive pressure inside to prevent the melted liquid metal 87 from being oxidized; after the low melting point alloy is completely melted, the motor can be started and operated. At this time, the conductive disk 86 of the inner rotating body 81 is connected to the collector ring 85 in the outer rotating body 82 through the liquid metal 87 to achieve wear-free and low-resistance operation. The liquid brush of the liquid brush slip ring assembly described in the present invention uses a low melting point alloy material with less corrosion, and is quickly heated before the motor starts to quickly melt the low melting point alloy material. The liquid brush working medium can be a low melting point alloy material such as tin-bismuth (Sn-Bi), indium-bismuth-tin (In-Bi-Sn) or indium-bismuth-tin-silver (In-Bi-Sn-Ag) with good fluidity, low corrosion and oxidation resistance. Before and during the operation of the motor, energize the constant temperature heater to turn the low melting point alloy into a super-low viscosity flowing conductive liquid metal 87, and at the same time open the inert gas release valve to fill and supplement the working space of the slip ring with inert gas to prevent the melted liquid metal 87 from being oxidized. After the motor stops running, turn off the constant temperature heating device and the inert gas release valve. The surfaces of the collector ring 85 and the conductive disk 86 are made of metal materials that have good wettability with the melted low melting point alloy material but are not easily corroded, such as nickel or gold. The depth of the V-shaped groove of the collector ring 85 should ensure that when all the low melting point metal liquid sinks to one side, it will not overflow. The contra-rotating dual-rotor motor using a liquid metal brush must place the motor shaft horizontally in the non-rotating state and is not allowed to shut down when the motor shaft is in the vertical state. In order to improve the isolation between the internal space of the slip ring and the outside atmosphere, the gap between the inner rotating body 81 and the outer rotating body 82 should be very small, preferably made into a labyrinth type. In order to isolate the penetration of the atmosphere in the static state, an axially magnetized magnetic ring 106 can be provided at the open end of the inner rotating body 81, and two liquid storage tanks 107 are opened at the corresponding part of the outer rotating body 82 to store magnetic liquid 108, see Figure 7 。When the motor is not rotating or rotating at a low speed, the magnetic liquid 108 is attracted by the magnetic ring 106 to form a seal to isolate the air, see Figure 15。When the motor speed is relatively high, the magnetic fluid 108 is separated from the magnetic ring 106 under the action of centrifugal force and completely sinks to the bottom of the liquid storage tank 107. To prevent the liquid metal from flowing to the root of the conductive disk during the stopping process, liquid retaining rings can be provided on both sides of the conductive disk. See Figure 14 。The contra-rotating dual-rotor motor of the present invention using a liquid metal brush uses a low-melting-point metal that is solid at room temperature as the liquid brush working medium, which is pollution-free. Under the protection of an inert gas, the molten metal liquid is difficult to be oxidized. The extremely low contact voltage drop and the large contact area make the liquid metal brush slip ring of the present invention small in size, light in weight, high-speed and long-life, thus making the contra-rotating dual-rotor motor lighter in weight and greater in power density, and is particularly suitable for use as the power of a fixed-wing electric aircraft sensitive to weight. For the power device of a coaxial contra-rotating propeller electric aircraft driven by a contra-rotating dual-rotor motor used for low-altitude aircraft flying only within hundreds of meters, the angle of attack of the two sets of propellers can be made into fixed angles of different angles, eliminating the angle-of-attack fine-tuning mechanism. The specific method is to first determine the angle of attack of one set of propellers through calculation, and then, under the condition that the relative speed of the two rotors is twice the rated speed of a single set of rotors, by changing the angle of attack of the other set, make the ground speed rates of the two sets of fans the same and both reach the rated speed, so as to obtain the optimal angle of attack of the other set of propellers. This can significantly reduce the complexity of the power device and also significantly reduce the manufacturing cost.

[0044] Example 7 Please refer to Figures 11 to 14 and Figure 16, A coaxial contra-rotating propeller dual-rotor axial magnetic field motor using a liquid metal slip ring, comprising a first rotor 39, a second rotor 19 and a slip ring. The slip ring includes an inner rotating body 81, an outer rotating body 82 and a constant temperature heater. The inner rotating body 81 includes an insulating member 105, a conductive disk 86 and a lead wire 30. The outer rotating body includes an insulating member 110, a collector ring 85, a lead wire, and an electric heating wire 96 and a temperature switch 102 embedded in the insulating member. Sealing bearings are provided at both ends between the inner and outer rotating bodies, and the inner and outer rotating bodies can rotate relative to each other; the inner cross-section of the collector ring 85 in the outer rotating body is a V-shaped groove, and a certain amount of low-melting-point alloy In51 / Bi32.5 / Sn16.5 is provided therein; before operation, first open the external inert gas release valve to allow the inert gas in the external gas storage tank to enter the slip ring through the pipeline and the pipe joint 8 and form a positive pressure inside to prevent oxidation after the metal melts; then energize the constant temperature heater. Since the normal ambient temperature is lower than the melting point of the alloy by 60°C, the normally closed temperature switch 102 is in the on state at this time. The current passes through the electric heating wire 96 to heat the V-shaped groove of the collector ring and finally reaches 80°C to melt the low-melting-point alloy therein into liquid metal 87. After the low-melting-point alloy is completely melted, the slip ring can rotate. At this time, the conductive disk of the inner rotating body is connected to the collector ring in the outer rotating body through the liquid metal, realizing wear-free and low-resistance operation. Turn on the operation switch of the motor controller, and the output current of the controller will sequentially pass through the motor lead wire 14, that is, the outer lead wire of the slip ring, the collector ring 85, the brush, the liquid metal 87, the conductive disk 86 and the inner lead wire 91 to feed the motor winding, causing the motor to rotate. After the motor rotates, the metal liquid that was originally mostly sunk in the lower V-shaped groove of the collector ring will rotate with the rotation of the conductive disk 86 and be distributed near the bottom tip of the entire V-shaped groove of the collector ring under the action of centrifugal force. After the motor starts, the axis of the motor can be pointed in any direction without worrying about the metal liquid flowing out of the V-shaped groove of the collector ring. Before and during the operation of the motor, turn on the constant temperature heating device to turn the low-melting-point alloy into a super-low-viscosity flowing conductive liquid, and at the same time open the inert gas release valve to fill and supplement the inert gas in the working space of the slip ring to prevent the melted metal liquid from oxidizing. Before the motor ends its operation, first turn the axis of the motor to the horizontal, then turn off the power of the motor controller and the constant temperature heating device to make most of the liquid metal sink into the lower V-shaped groove of the collector ring and solidify. Finally, close the inert gas valve. The surfaces of the collector ring and the conductive disk are made of metal materials that have good wettability with the melted low-melting-point alloy material but are not easily corroded, such as nickel or gold. The liquid brush working medium is selected from low-melting-point alloy materials such as tin-bismuth (Sn-Bi) and indium-bismuth-tin (In-Bi-Sn) that have good fluidity, low corrosion and oxidation resistance after melting. This contra-rotating dual-rotor motor using liquid metal brushes must place the motor shaft horizontally in the non-rotating state and is not allowed to shut down when the motor shaft is in the vertical state.In order to improve the isolation effect between the internal space of the slip ring and the outside atmosphere, the gap between the inner rotating body 81 and the outer rotating body 82 should be as small as possible and preferably made into a labyrinth type, and the bearings used should also be low-loss sealed bearings. In order to better isolate the intrusion of the atmosphere in the stationary state, a sealing disk can be made at the open end of the inner rotating body 81, a ring-shaped sealing groove 103 with a V-shaped cross-section can be made at the corresponding position of the outer rotating body, and a certain amount of sealing grease is provided therein. In order to overcome the shortcoming that the slip ring axis must be in a horizontal state to preheat and start, please refer to... Figure 16 , on both sides of the liquid metal slip ring near the large end, there are multi-layer mesh rings woven with nickel wires, and the molten low-melting-point metal is adsorbed by the surface tension between the nickel wires of the mesh ring and the molten low-melting-point alloy. Since the distance between the conductive disk and the V-shaped groove is less than 0.5 mm, even when the axis is in the vertical direction and the motor is stationary, the molten low-melting-point alloy and the nickel conductive disk remain connected due to high wettability. The liquid metal slip ring made in this way will not require the axis to be preheated in the horizontal state. Since the present invention is a counter-rotating dual-rotor motor using a liquid metal brush, using a low-melting-point metal that is solid at room temperature as the working medium of the liquid brush is pollution-free. The molten metal liquid is difficult to be oxidized under the protection of inert gas. The extremely low contact voltage drop and large contact area make the liquid metal brush slip ring of the present invention small in volume, light in weight, high-speed and long-life, thus making the counter-rotating dual-rotor motor lighter in weight and larger in power density. Especially when a ducted power unit made of a dual-air-gap or multi-air-gap axial magnetic field motor is used, it is particularly suitable for medium and large electric aircraft.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electric aircraft power plant using a contra-rotating dual-rotor motor, characterized in that The invention comprises a counter-rotating dual-rotor motor, a motor controller, a first propeller (12), a second propeller (13), an angle of attack fine-tuning system and a slip ring mechanism; the first propeller (12) and the second propeller (13) are mounted on the counter-rotating dual-rotor motor, and the counter-rotating dual-rotor motor is connected to the motor controller via a slip ring mechanism; the first propeller (12) and the second propeller (13) have opposite angles of attack and opposite directions of rotation, and at least one set of propellers is provided with an angle of attack fine-tuning system at its root for adjusting the angle of attack of the propellers so that the two sets of propellers have the same ground speed rate.

2. The electric aircraft power plant using a contra-rotating dual-rotor motor according to claim 1, characterized in that, The counter-rotating dual-rotor motor comprises a first rotor (1), a second rotor (2), a first rotor output shaft (3) and a second rotor output shaft (4); the first rotor output shaft (3) is connected to the first rotor (1), the second rotor output shaft (4) is connected to the second rotor (2), the second rotor (2) is arranged on the first rotor output shaft (3) via a bearing, the lead wire of the first rotor (1) is connected to the corresponding electrode of the slip ring mechanism, and the first propeller (12) and the second propeller (13) are respectively mounted on the first rotor output shaft (3) and the second rotor output shaft ( 4); the angle of attack fine-tuning system comprises an angle of attack adjustment mechanism installed at the root of the propeller, a first speed sensor (8), a second speed sensor (7), an electric thrust cylinder (35) and an angle of attack control circuit; the first speed sensor (8) and the second speed sensor (7) are both installed on the side of the first rotor (1) and the second rotor (2) through a fixing seat (5); the electric thrust cylinder (35) is connected to the angle of attack adjustment mechanism; the angle of attack control circuit subtracts the speeds of the two rotors detected by the speed sensor, amplifies the difference signal and then stimulates the electric thrust cylinder to adjust the angle of attack of its propeller.

3. The electric aircraft power plant using a contra-rotating dual-rotor motor according to claim 2, characterized in that, The angle of attack adjustment mechanism comprises a bearing and a crank (18) mounted at the root of the blade and a telescopic sleeve (20) driven by an electric push cylinder (35). The telescopic sleeve (20) is provided with a group of inclined grooves (19) which are at a set angle to the axis. The end of the crank (18) at the root of the blade is inserted into the inclined groove (19) of the telescopic sleeve (20). When the sleeve (20) is pushed forward and backward by the push rod of the electric push cylinder (35), the inclined groove (19) drives the crank to change the angle of attack of the blade.

4. The electric aircraft power plant using a contra-rotating dual-rotor motor according to claim 1, characterized in that, The slip ring mechanism comprises an inner rotating body (81), an outer rotating body (82), a low melting point alloy (87) and a constant temperature heater, wherein a bearing is arranged between the inner rotating body (81) and the outer rotating body (82), the inner rotating body (81) is fixedly sleeved on the shaft and fixedly connected to the first rotor, the constant temperature heater is embedded on the outer rotating body (82), the low melting point alloy (87) is arranged between the inner rotating body (81) and the outer rotating body (82), and when the constant temperature heater is working, the low melting point alloy melts, and the inner rotating body and the outer rotating body can rotate relative to each other.

5. The electric aircraft power plant using a contra-rotating dual-rotor motor according to claim 4, characterized in that, The inner rotating body comprises an inner shaft sleeve (84), an insulating component (105) and a conductive disk (86), the insulating component is sleeved on the inner shaft sleeve (84), the inner shaft sleeve (84) is sleeved on the shaft, and a plurality of circles of conductive disks (86) are arranged on the outer side of the insulating component; The outer rotating body includes an insulating member (105), a slip ring (85), and an external lead wire (92). A slip ring (85) matching the conductive disk (86) is provided inside the insulating member (105) of the outer rotating body. The conductive disk (86) is arranged inside the slip ring (85), and a low-melting-point alloy (87) is arranged between the conductive disk (86) and the slip ring (85). The slip ring (85) is a circular ring with a V-shaped groove in cross-section, and the low-melting-point alloy (87) is arranged in the V-shaped groove. An air passage is provided on the insulating member of the outer rotating body for introducing an inert gas between the conductive disk (86) and the slip ring (85). The constant-temperature heater includes a temperature switch (102) and a heating wire (96), and the heating wire (96) is connected to the temperature switch (102).

6. The electric aircraft power plant using a contra-rotating dual-rotor motor according to claim 4, characterized in that, The conductive disk is a flat circular ring-shaped assembly formed by welding a plurality of fan-shaped segments that can extend into the V-shaped groove of the slip ring to a bus ring. Its outer side is thinner and has a spiky cross-section. A liquid retaining ring is provided on the conductive disk.

7. The electric aircraft power plant using a contra-rotating dual-rotor motor according to claim 4, characterized in that, The gap between the inner rotating body (81) and the outer rotating body (82) is of a labyrinth type. A sealing disk (104) is provided at the open end of the inner rotating body. A ring-shaped sealing groove (103) with a V-shaped cross-section is provided at the corresponding position of the outer rotating body and a sealing grease is provided therein, or a magnet ring (106) with axial magnetization is provided at the open end of the inner rotating body (81). Two liquid storage grooves (107) are opened at the corresponding part of the outer rotating body (82) for storing a magnetic fluid (108) made of a low-volatility liquid and micro-nano soft magnetic powder.

8. An electric aircraft power plant of a contra-rotating dual-rotor motor with a ducted structure, characterized in that, An electric aircraft power device using a contra-rotating dual-rotor motor as described in claim 5, including a front support rod (25), a rear support rod (26), a duct cylinder (29), and a central shaft (30). The front support rod (25) and the rear support rod (26) are respectively provided inside the duct cylinder (29) at the front and rear to jointly support a non-rotating central shaft (30). The first rotor (1) and the second rotor (2) are respectively arranged outside the central shaft (30) through bearings inside them and can rotate around the central shaft (30). A first fan (27) and a second fan (28) are respectively provided on the first rotor (1) and the second rotor (2). The attack angle directions of the two groups of fans are opposite, and at least one group of fans is provided with an attack angle adjustment system. The attack angle fine adjustment system includes an attack angle adjustment mechanism installed at the root of the fan, a first speed sensor (8) and a second speed sensor (7) installed on the fixed seat (5) close to the first rotor (1) and the second rotor (2), an electric push cylinder (35), and an attack angle control circuit. The attack angle control circuit subtracts the speeds of the two rotors detected by the speed sensors, and after amplifying the difference signal, adjusts the attack angle of one group of propellers.

9. The electric aircraft power unit of a contra-rotating dual-rotor motor with a ducted structure according to claim 8, characterized in that, The angle of attack adjusting mechanism includes a bevel gear (21) at the root of the fan, an adjusting ring (22), a servo motor (16), and a slip ring (24). The right side of the adjusting ring (22) is the main gear, the left side of the adjusting ring (22) is the secondary gear, and the inner side of the adjusting ring (22) is arranged on the second rotor shaft (4) through a bearing. The bevel gear (23) on the output shaft of the servo motor (16) meshes with the secondary gear of the adjusting ring, and the main gear of the adjusting ring meshes with the bevel gear (21). The base of the servo motor (16) is fixedly connected to the second motor shaft (4).

10. An electric aircraft power plant using a contra-rotating dual-rotor motor according to claim 4, characterized in that, The contra-rotating dual-rotor motor is a center-through shaft fixed structure, which is axially connected and integrated by multiple axial magnetic ventilation gap motor units. The number of armature rotor units ≥ 2, and the number of working air gaps ≥ 4.

Images