Planetary gear hybrid power system for unmanned aerial vehicle

Abstract

The invention belongs to the field of unmanned aerial vehicle hybrid power systems, and particularly relates to a planetary gear hybrid power system for an unmanned aerial vehicle, which comprises a set of planetary gears, a piston engine, a main propulsion propeller, a starting generator, a bidirectional controller, a power battery and four sets of vertical take-off and landing power assemblies, the planetary gear is provided with two power inputs, one is that a sun gear is connected with an output shaft of the piston engine, the other is that an inner gear ring is connected with a rotor of the generator, and a planet carrier serves as power output to be connected with a main propulsion propeller.

Description

Technical Field

[0001] This invention belongs to the field of unmanned aerial vehicle (UAV) hybrid power systems, specifically relating to a planetary gear hybrid power system for UAVs. The power system architecture uses a set of planetary gears to couple the power output of the piston engine and the starter generator to the main propeller. Through the coordinated control of the starter generator and the piston engine, seamless power switching, energy recovery, and high dynamic response are achieved. Background Technology

[0002] Currently, in the field of power systems for small and medium-sized unmanned aerial vehicles (UAVs), there are pure fuel-powered systems and pure electric-powered systems, while hybrid power systems are less commonly used. Pure fuel-powered UAVs cannot provide vertical takeoff and landing (VTOL) capabilities, and pure electric-powered systems have short flight times. Current VTOL hybrid UAVs separate the electric power system for VTOL and the fuel-powered system for cruising, with no interoperability between the two systems. While this simplifies control, the electric power system has a significant dead weight after takeoff, reducing the UAV's flight time. Current hybrid power systems for new energy vehicles have solved the coupling relationship between fuel and electric power systems; however, due to their complex system architecture, complex control algorithms, and low power density, these hybrid systems are rarely used in small and medium-sized UAVs. Summary of the Invention

[0003] The purpose of this invention is to address the problem of excessive dead weight in current vertical take-off and landing (VTOL) UAV hybrid power systems that separate oil and electric power sources. This invention provides a planetary gear hybrid power system for UAVs, which adopts a coaxial parallel topology and couples the power of the piston engine and the generator through planetary gears, thereby reducing the dead weight of the UAV power system and solving the problem of engine power reduction during high-altitude flight.

[0004] The technical solution of this invention is: This invention provides a planetary gear hybrid power system for unmanned aerial vehicles, comprising a planetary gear set, a piston engine, a main propeller, a starter generator, a bidirectional controller, a power battery, and four sets of vertical take-off and landing power components. The planetary gear has two power inputs: one is the sun gear connected to the output shaft of the piston engine, and the other is the internal gear ring connected to the rotor of the generator. The planet carrier serves as the power output, connecting to the main propeller.

[0005] Furthermore, the generator rotor and the planetary gear internal gear ring are designed as an integrated structure. The inner surface of the internal gear ring is a meshing tooth, and the outer surface is covered with the generator's permanent magnet. The generator stator is fixed to the piston engine housing by screws. The generator's rated power meets the power requirements of the UAV during level flight cruise.

[0006] Furthermore, the planetary gear adopts a small transmission ratio design, with a transmission ratio of 3.

[0007] Furthermore, the bidirectional controller is used to realize bidirectional energy flow, converting the three-phase AC power of the generator into DC power to charge the battery, and also realizing the electric state control of the generator.

[0008] Furthermore, the piston engine adopts a two-cylinder horizontally opposed structure and operates in a two-stroke mode.

[0009] Furthermore, during the aircraft's start-up phase, the power battery first supplies power to the starter generator, which drives the piston engine to start, operating at a high-efficiency speed. Then, the piston engine, through planetary gears, drives the starter generator to generate electricity, charging the power battery. Simultaneously, the power battery supplies power to the four vertical takeoff and landing (VTOL) propulsion units, lifting the aircraft to a specific altitude. By adjusting the rotational speed of the four rotors in the four VTOL propulsion units, the aircraft's attitude is switched, enabling it to enter level flight propulsion.

[0010] Furthermore, during cruise, the piston engine maintains its high-efficiency operating speed range, serving as the primary power source. The starter-generator operates in generator mode, recovering kinetic energy from the main propeller and charging the battery. When power demand increases, the starter-generator switches to electric mode, and the power from both is coupled to the main propeller via planetary gears.

[0011] Furthermore, the four rotors in the four vertical takeoff and landing (VTOL) power units can be turned on or off according to the speed requirements of the drone. When the drone is cruising at low speed, the four rotors can be turned off, and the piston engine drives the main propeller to provide power. When the drone needs to cruise at high speed, the four rotors are turned on, providing power simultaneously with the main propeller.

[0012] The advantages of this invention are: This invention enables the coupling of the electric and fuel power systems of a vertical takeoff and landing (VTOL) drone, reducing dead weight; at the same time, it uses planetary gears to couple the electric power and engine power, compensating for the engine's power loss at high altitudes. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a diagram of a planetary gear hybrid power system architecture for an unmanned aerial vehicle (UAV). Figure 2 This is a structural diagram of a planetary gear hybrid power engine for an unmanned aerial vehicle (UAV) according to the present invention. Figure 3 This is a structural diagram of a brushless motor with integrated planetary gears according to the present invention; Figure 4 This is a diagram of a planetary gear structure for an unmanned aerial vehicle (UAV) according to the present invention. Among them: 1-piston engine, 2-generator, 3-planetary gear, 4-main propeller, 21-generator housing, 22-housing mounting flange, 23-stator core, 24-permanent magnet, 31-internal gear ring, 32-planetary gear, 33-sun gear. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0016] Small and medium-sized drones are particularly sensitive to cost and weight. This invention addresses this by incorporating planetary gears into the power system of these drones, taking into account their specific power structure characteristics. The power from the electric motor and engine is coupled and output to the propeller. The electric motor can function as both a power output motor and a generator. Especially at high altitudes, where air density decreases and air intake is reduced, piston engines experience incomplete combustion and a significant power drop. In this situation, lithium batteries can power the electric motor to compensate for the engine's power loss. During cruising, the engine can drive the electric motor to generate electricity, charging the lithium batteries.

[0017] like Figure 1 The diagram shows the framework of a hybrid-powered unmanned aerial vehicle (UAV), consisting of two power systems: a quadcopter vertical takeoff and landing (VTOL) system powered by batteries, and a main propeller driven by a fuel-powered aviation piston engine. The two power systems are connected via planetary gears and a generator. The sun gear serves as the engine's power input, the internal gear ring as the generator's power input, and the planetary carrier as the power output, connecting to the propeller. When the engine drives the propeller, it simultaneously drives the generator to rotate. In this mode, the generator operates in power generation mode, and the generated electricity charges the batteries via a bidirectional controller.

[0018] like Figure 2 , 3Figure 4 shows a three-dimensional structural diagram of an aircraft piston engine, starter generator, planetary gears, and propeller. The starter generator is fixed to the engine casing via a mounting flange. The engine casing has a circular shoulder concentric with the output shaft, ensuring the concentricity of the motor output shaft and the engine output shaft. The engine output shaft is interference-fitted with the sun gear of the planetary gears to ensure reliable connection. The propeller is connected to the planet carrier of the planetary gears via screws. The number of teeth on the sun gear is set to Zs, the number of teeth on the internal gear ring is set to Zr, and the transmission ratio is set to i = 1 + Zr / Zs = 3 to ensure matching between the high-speed output of the engine and the low-speed, high-efficiency drive of the propeller.

[0019] The present invention provides a planetary gear hybrid power system for unmanned aerial vehicles, comprising a planetary gear set, a piston engine, a main propeller, a starter generator, a bidirectional controller, a power battery, and four sets of vertical take-off and landing power components. The planetary gear has two power inputs: one is the sun gear connected to the output shaft of the piston engine, and the other is the internal gear ring connected to the rotor of the generator. The planet carrier serves as the power output, connecting to the main propulsion propeller.

[0020] The generator rotor and the planetary gear internal gear ring are designed as an integrated structure. The inner surface of the internal gear ring is a meshing tooth, and the outer surface is covered with the generator's permanent magnet. The generator stator is fixed to the piston engine housing with screws. The generator's rated power meets the power requirements of the UAV during level flight cruise.

[0021] The planetary gear is designed with a small transmission ratio of 3.

[0022] The bidirectional controller is used to realize bidirectional energy flow, converting the three-phase AC power of the generator into DC power to charge the battery, and also realizing the motor state control of the generator.

[0023] The piston engine is a small-displacement piston engine specifically designed for aviation. It features a horizontally opposed twin-cylinder configuration, effectively eliminating engine vibration. Operating on a two-stroke cycle, it is suitable for high-speed, high-power operation and boasts a high power-to-weight ratio.

[0024] During the aircraft's start-up phase, the power battery first supplies power to the starter generator, which drives the piston engine to start, operating at a high-efficiency speed. Then, the piston engine, through planetary gears, drives the starter generator to generate electricity, charging the power battery. Simultaneously, the power battery supplies power to the four vertical takeoff and landing (VTOL) propulsion units, lifting the aircraft to a specific altitude. By adjusting the rotational speed of the four rotors in the four VTOL propulsion units, the aircraft's attitude is switched, enabling it to enter level flight propulsion.

[0025] During cruise, the piston engine operates at its high-efficiency RPM range, serving as the primary power source. The starter-generator operates in generator mode, recovering kinetic energy from the main propeller and charging the battery. When power demand increases, the starter-generator switches to electric mode, and the power from both is coupled to the main propeller via planetary gears.

[0026] During vertical takeoff and landing, the four rotors adjust the aircraft's attitude and provide lift. At this time, the aircraft's power comes from the battery, and the starter generator operates in generator mode. During low-speed cruise in level flight, the engine drives the starter generator to generate electricity, which charges the battery via a two-way controller; the four rotors are not operational. When high-speed cruise or high-maneuvering is required, high thrust is needed. In this mode, the starter generator operates in electric mode, and the controller controls the starter generator's torque output, which is coupled to the engine's torque via planetary gears and ultimately delivered to the main propeller. Simultaneously, the aircraft's cruise speed can be further increased by activating all four rotors.

[0027] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. This invention provides a planetary gear hybrid power system for unmanned aerial vehicles (UAVs), characterized in that, It includes a planetary gear set, piston engine, main propeller, starter generator, bidirectional controller, power battery and 4 sets of vertical take-off and landing power components; The planetary gear has two power inputs: one is the sun gear connected to the output shaft of the piston engine, and the other is the internal gear ring connected to the rotor of the generator. The planet carrier serves as the power output, connecting to the main propeller.

2. The planetary gear hybrid power system for an unmanned aerial vehicle according to claim 1, characterized in that, The generator rotor and the planetary gear internal gear ring are designed as an integrated structure. The inner surface of the internal gear ring is a meshing tooth, and the outer surface is covered with the generator's permanent magnet. The generator stator is fixed to the piston engine housing with screws. The generator's rated power meets the power requirements of the UAV during level flight cruise.

3. The planetary gear hybrid power system for an unmanned aerial vehicle according to claim 1, characterized in that, The planetary gear is designed with a small transmission ratio of 3.

4. A planetary gear hybrid power system for an unmanned aerial vehicle according to claim 1, characterized in that, The bidirectional controller is used to realize bidirectional energy flow, converting the three-phase AC power of the generator into DC power to charge the battery, and also realizing the motor state control of the generator.

5. A planetary gear hybrid power system for an unmanned aerial vehicle according to claim 1, characterized in that, The piston engine adopts a two-cylinder horizontally opposed structure and operates in a two-stroke mode.

6. A planetary gear hybrid power system for an unmanned aerial vehicle according to claim 1, characterized in that, During the aircraft's start-up phase, the power battery first supplies power to the starter generator, which drives the piston engine to start, operating at a high-efficiency speed. Then, the piston engine, through planetary gears, drives the starter generator to generate electricity, charging the power battery. Simultaneously, the power battery supplies power to the four vertical takeoff and landing (VTOL) propulsion units, lifting the aircraft to a specific altitude. By adjusting the rotational speed of the four rotors in the four VTOL propulsion units, the aircraft's attitude is switched, enabling it to enter level flight propulsion.

7. A planetary gear hybrid power system for an unmanned aerial vehicle according to claim 1, characterized in that, During cruise, the piston engine operates at its highest efficiency speed, serving as the primary power source. The starter-generator operates in generator mode, recovering kinetic energy from the main propeller and charging the battery. When power demand increases, the starter-generator switches to electric mode, and the power from both is coupled to the main propeller via planetary gears.

8. A planetary gear hybrid power system for an unmanned aerial vehicle according to claim 1, characterized in that, The four rotors in the four vertical takeoff and landing (VTOL) power units can be turned on or off according to the drone's speed requirements. When the drone is cruising at low speed, the four rotors can be turned off, and the piston engine drives the main propeller to provide power. When the drone needs to cruise at high speed, the four rotors are turned on, providing power in conjunction with the main propeller.

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