A propeller folding mechanism for a foldable propeller

Abstract

The utility model discloses a kind of propeller folding mechanism of foldable propeller, including multiple groups of actuating unit, each group of actuating unit includes propeller arm, at least two propeller blades, stopper and drive motor controlled by flight control system, drive motor is connected in the end of propeller arm, drive motor is used to drive propeller blade forward rotation or reverse rotation, propeller blade is hinged on drive motor power output shaft, the number of stopper is at least two, respectively installed in the both sides of propeller arm. At least two folding spaces of propeller blade are formed between stopper, stopper is located in the path range of propeller blade. When propeller folds, stopper is pushed out towards the plane where propeller blade is located. Compared with existing propeller folding mechanism, the utility model can greatly improve the safety and reliability of propeller folding structure and complete machine, without significantly increasing the moment of inertia of propeller and the weight of complete machine, simple structure, low cost, control is more accurate.

Description

Technical Field

[0001] This utility model relates to the field of propeller technology for low-altitude aircraft such as drones, eVTOLs, flying cars, and air-to-ground integrated aircraft, and specifically to a propeller folding mechanism and folding method for foldable propellers of low-altitude aircraft such as drones, eVTOLs, flying cars, and air-to-ground integrated aircraft. Background Technology

[0002] Unmanned aerial vehicles (UAVs), electric vertical takeoff and landing (eVTOL) aircraft, flying cars, and air-to-ground integrated aircraft commonly use fixed propellers as lift and propulsion devices. To improve the portability and deployment flexibility of these devices, and to reduce their space occupation during parking, transportation, and ground operation, foldable propellers have emerged and are widely used in the power systems of consumer and industrial low-altitude aircraft. However, the applicant has found that current foldable propellers suffer from significant problems such as complex structure, heavy weight, low reliability, and high maintenance costs.

[0003] Currently, propeller folding mechanisms mainly employ two mainstream technical solutions: integrating a mechanical folding mechanism inside the propeller hub, or using an independent servo motor or electric motor to directly drive the blades to rotate and achieve folding / unfolding. The first type of solution integrates a mechanical folding mechanism inside the propeller hub, typically including components such as springs, pawls, and locking pins. This type of mechanism utilizes centrifugal force or electromagnetic actuators to achieve automatic propeller deployment: when the propeller reaches a certain speed, the centrifugal force overcomes the spring preload, driving the locking mechanism to unlock and unfold the blades; at low speeds or when the machine is stopped, folding is achieved by spring reset or gravity, such as the invention patent CN120057327B, which describes a reed-based foldable UAV propeller.

[0004] The second type of solution uses independent servos or micro motors to directly drive the propellers to rotate in order to achieve folding and unfolding. For example, the invention patent with announcement number CN115924143B describes a deployable multi-rotor UAV platform. When the multi-rotor UAV platform completes its flight mission and needs to land and fold for storage, the arm components rotate in the same direction in the same horizontal plane under the drive of the servos, covering the sides of the fuselage components and being fixedly positioned by the arm clamps. At the same time, the propeller components connected to the first end of each arm component automatically fall down and fold up by their own weight after losing power.

[0005] However, the applicant found that no matter which of the above technical solutions is adopted, there are prominent problems such as complex structure, large weight, low reliability, and high maintenance cost, which will affect the flight safety, operation and maintenance efficiency and user experience of low-altitude aircraft. Utility Model Content

[0006] The present invention aims to provide a folding mechanism for a foldable propeller, so as to solve the problems of complex structure, heavy weight, low reliability and high maintenance cost of existing low-altitude aircraft propeller folding mechanisms.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A folding mechanism for a foldable propeller includes multiple sets of actuation units. Each set of actuation units includes a propeller arm, at least two propeller blades, limiters, and a drive motor controlled by a flight control system. The drive motor is connected to the end of the propeller arm and drives the propeller blades to rotate forward or backward. The propeller blades are hinged to the power output shaft of the drive motor. There are at least two limiters, which are respectively installed on both sides of the propeller arm. The limiters form a folding space for at least two propeller blades. The limiters are located within the path range of the propeller blades. When the propeller is folded, the limiters are pushed out toward the plane where the propeller blades are located.

[0008] The applicant found that existing folding mechanisms for low-altitude aircraft propellers suffer from structural complexity, heavy weight, low reliability, and high maintenance costs. This is due to the placement of the limiting device on a high-speed rotating component. Taking the first type of solution as an example, a complex mechanical structure is integrated inside the rotor hub, with numerous precision parts integrated within the high-speed rotating hub, requiring extremely high machining accuracy and assembly precision. The high-speed rotating component is prone to generating enormous centrifugal force and vibration, leading to internal spring failure, locking pin jamming, or wear, resulting in a high risk of malfunction. The heavy weight and complex internal mechanism significantly increase the inertia of the rotating components, negatively impacting the motor's power response and the overall flight range. Similarly, using independent servos or motors to directly drive the blades to achieve folding / unfolding, while this solution offers direct control, it still requires mounting the actuator and its transmission mechanism on the rotating rotor hub, resulting in a large rotating mass, increased system inertia, and the need for additional slip rings or wireless power transfer devices to power the motors on the rotating components, further increasing system complexity and cost. Therefore, the applicant identified the fundamental problem with the existing technical solution as follows: the limiting device (such as locking pin, pawl, etc.) is directly set on the high-speed rotating hub or blade assembly, which causes the limiting device to be subjected to high centrifugal force, strong vibration and complex load for a long time. This not only exacerbates the risk of structural failure, but also leads to increased system weight, decreased reliability and maintenance difficulties.

[0009] The advantages of this solution are: 1. Significantly improved reliability This solution completely abandons the traditional design approach of integrating precision components such as springs, locking pins, motors, and sensors into a high-speed rotating rotor hub. The propeller blades themselves no longer bear any additional structures or electronic components; they are driven directly by the drive motor, avoiding problems such as mechanical fatigue, contact failure, or signal interruption caused by centrifugal force, vibration, and temperature changes.

[0010] This invention ingeniously utilizes a drive motor as the folding actuation mechanism—by controlling its forward and reverse rotation and angle, the propeller blades unfold and fold, eliminating the need for a dedicated actuation motor or servo motor. This not only reduces potential failure points but also makes the entire rotating system extremely simple in structure and stable in operation. Even in harsh environments such as low temperature, high humidity, and strong electromagnetic interference, the system can still operate reliably, significantly improving the flight safety of UAVs in high-risk scenarios such as industrial inspection, emergency rescue, and border patrol.

[0011] Furthermore, since there is no built-in locking mechanism, there is no need to worry about fatal hazards such as "unlocked takeoff" or "accidental unlocking during flight," truly achieving an intrinsically safe folding control mechanism.

[0012] 2. The overall weight and inertia are significantly reduced. In traditional folding designs, the non-functional components integrated inside the propeller hub, such as actuators, locking mechanisms, and slip rings, significantly increase the rotating mass, leading to an increase in the system's moment of inertia. According to the principles of rigid body dynamics, the greater the moment of inertia, the higher the torque required for acceleration, the slower the motor response, and the higher the energy consumption.

[0013] In this invention, the newly added functional component (limiter) is located on the non-rotating fuselage side and only intervenes briefly during folding. The rotating part of the propeller consists only of the propeller blades and the drive motor's power output shaft, resulting in a simplified structure and minimizing the rotational inertia of the rotating part. Calculations show that compared to the traditional built-in locking propeller hub, this solution can reduce the equivalent rotational inertia of the propeller system by 15%-30%.

[0014] This improvement will also bring the following advantages: Faster power response: The motors can complete attitude adjustments in a shorter time, improving the aircraft's maneuverability; Lower energy consumption: Reduces energy loss during acceleration, especially effective in frequent takeoffs and landings or variable flight missions; Extended battery life: Reduced overall power consumption indirectly improves battery efficiency and extends effective operating time; Extended motor life: Reduced load lowers motor temperature rise and wear, extending its service life.

[0015] 3. Simple structure and low cost It eliminates the need for expensive rotary actuators, slip rings, and other devices. Only limit devices are required, significantly reducing manufacturing costs.

[0016] 4. Precise and reliable control By controlling the speed, direction, and angle of the drive motor, the folding angle and speed of the propeller blades can be precisely controlled, achieving various states such as half-folding and full-folding. The control logic is simple and robust.

[0017] Furthermore, the limiter is an electric push rod, and its extension and retraction are controlled by the flight control system. Both the limiter and the drive motor are controlled by the same flight control system, eliminating the need for an additional controller. This results in high system integration, low communication latency, and the flight control system can dynamically adjust the timing of the limiter's extension based on multi-dimensional data such as rotational speed, steering, and angle, ensuring a smooth and reliable folding process.

[0018] Furthermore, the two electric push rods are arranged in a mirror image along the propeller arm axis to ensure that the electric push rods can act stably and synchronously on the root of the blade or the predetermined contact area during the folding process, so as to achieve uniform limiting on both sides and avoid structural eccentricity, vibration or jamming caused by unilateral force.

[0019] Furthermore, the distance from the farthest electric actuator to the drive motor's power output shaft is equal to the propeller blade length. During folding, the electric actuator contacts the end of the propeller blade. Since the point of application of the electric actuator is located at the end of the propeller blade—the position farthest from the center of rotation—the limiting reaction force it provides has the largest lever arm. According to the principle of torque balance, under the same external force disturbance, the constraint force required for end limiting is the smallest, which can effectively prevent the propeller blade from accidentally unfolding due to transportation vibration, wind load, or collision, significantly enhancing the structural stability in the folded state.

[0020] Furthermore, the extendable portion of the electric actuator serves as a blocking component. When the propeller blades are folded, the height of the blocking component is at least 0.1 cm higher than the plane of the propeller blades. The blocking component, extending a certain distance above the blade plane, radially constrains the propeller blades, effectively preventing the folded blades from tilting upwards or completely disengaging from the folded position due to external impacts such as transport bumps, sudden braking, or rolling. This avoids the risk of "dislocation" and significantly improves structural safety in the folded state.

[0021] Furthermore, the blocking element is made of one or more flexible materials selected from silicone, polyurethane, thermoplastic elastomers, and foamed materials, with a hardness lower than 90HA. During the propeller blade folding process, contact and compression inevitably occur between the propeller blade tip and the blocking element. Using a flexible material can effectively absorb impact energy, thereby protecting the propeller blade. Attached Figure Description

[0022] Appendix Figure 1This is a front view of the folding mechanism of a foldable propeller according to the present invention in its folded state. Appendix Figure 2 This is a top view of the folding mechanism of a foldable propeller according to the present invention in its folded state. Appendix Figure 3 This is a front view of the propeller folding mechanism of the present invention in a semi-folded state. Appendix Figure 4 This is a top view of the propeller folding mechanism of the present invention in a semi-folded state. Appendix Figure 5 This is a front view of the fully folded state of the propeller folding mechanism of the present invention. Appendix Figure 6 This is a top view of the fully folded state of the propeller folding mechanism of the present invention. The reference numerals in the accompanying drawings include: 1 for the first propeller blade, 2 for the second propeller blade, 3 for the first electric push rod, 4 for the second electric push rod, 5 for the propeller arm, and 6 for the drive motor. Detailed Implementation

[0023] The following detailed description illustrates the specific implementation methods: A foldable propeller folding mechanism includes multiple sets of actuation units. Each set of actuation units includes a propeller arm 5, a first propeller blade 1, a second propeller blade 2, and a limiter that is an electric push rod or a hydraulic push rod. In this embodiment, an electric push rod is used. The first electric push rod 3, the second electric push rod 4, and a drive motor 6 controlled by the flight control system are also included.

[0024] The drive motor 6 is mounted on the end of the propeller arm 5 via a motor base. The drive motor 6 drives the first propeller blade 1 and the second propeller blade 2 to rotate forward or backward. The first propeller blade 1 and the second propeller blade 2 are hinged to the power output shaft of the drive motor 6, and the first propeller blade 1 and the second propeller blade 2 are directly driven by the drive motor 6. The first propeller blade 1 and the second propeller blade 2 are wider near the drive motor 6 (root) and gradually narrow towards the end, forming a tapered profile.

[0025] The first electric push rod 3 and the second electric push rod 4 are respectively mounted flush on both sides of the propeller arm 5, forming a folding space between the first electric push rod 3 and the second electric push rod 4 for the first propeller blade 1 and the second propeller blade 2. The extendable part of the first electric push rod 3 and the second electric push rod 4 is a blocking member, which is made of rubber with a hardness of 60HA. The distance from the first electric push rod 3 and the second electric push rod 4 to the power output shaft of the drive motor 6 is equal to the length of the propeller blade. When the propeller is folded, the blocking member flexibly contacts the ends of the first propeller blade 1 and the second propeller blade 2, and the blocking member can be pushed out toward the plane of the propeller blade, 1cm above the plane of the propeller blade. The first electric push rod 3 and the second electric push rod 4 are also controlled by the flight control system. The first electric push rod 3, the second electric push rod 4 and the drive motor 6 are all controlled by the same flight control system, without the need for an additional controller. The system has a high degree of integration and low communication latency. The flight control system can dynamically adjust the timing of the push-out of the first electric push rod 3 and the second electric push rod 4 according to multi-dimensional data such as speed, direction and angle, to ensure a smooth and reliable folding process.

[0026] The folding method of this folding mechanism includes the following steps: S1. Propeller folding preparation: The flight control system sends a command to drive motor 6 to put drive motor 6 at a low speed of 5RPM; S2. Complete half-folding: Drive motor 6 drives the first propeller blade 1 to rotate in the forward direction. After passing the first electric push rod 3 and entering the folding space of the two propeller blades, the flight control system controls the blocking part on the first electric push rod 3 to push out and limit the first propeller blade 1. S3. Complete full folding: The drive motor 6 drives the second propeller blade 2 to rotate in the opposite direction. After passing the second electric push rod 4 and entering the folding space of the two propeller blades, the flight control system controls the blocking part on the second electric push rod 4 to push out and limit the second propeller blade 2.

[0027] When the folding mechanism needs to be unfolded, the flight control system sends commands to the drive motor 6, the first electric push rod 3, and the second electric push rod 4. The blocking parts on the first electric push rod 3 and the second electric push rod 4 will retract, and the first propeller blade 1 and the second propeller blade 2 will unfold and rotate under the action of the drive motor 6, thereby enabling flight.

[0028] This structure has the following significant advantages and effects: 1. The structure is highly simplified, and the reliability is significantly improved. The rotating parts have no additional actuation mechanisms or electronic components, which avoids problems such as spring failure and locking pin jamming caused by centrifugal force and vibration in traditional solutions, and fundamentally improves the stability of the system in long-term operation.

[0029] 2. Lightweight and low inertia, which helps improve battery life and response speed. All new functional components are located on non-rotating parts, and the rotating mass only includes the blades themselves, which significantly reduces the moment of inertia, reduces the load on the drive motor, and indirectly extends the battery life.

[0030] 3. The folding process is smooth and safe, and supports intelligent control. Flexible contact and precise timing control enable "soft limit and stable locking", supporting multiple modes such as half-folding and full-folding, and are suitable for highly automated scenarios such as automated airports and swarm drones.

[0031] 4. Easy to maintain and low cost The electric actuator is a standard component, installed on the fixed end of the machine body, making it easy to replace and repair; it eliminates the need for complex devices such as slip rings and wireless power supply, significantly reducing manufacturing and maintenance costs.

[0032] The above descriptions are merely embodiments of this utility model. Commonly known technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solution of this utility model. These modifications and improvements should also be considered within the scope of protection of this utility model, and will not affect the effectiveness of the implementation of this utility model or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A propeller folding mechanism of a foldable propeller, comprising a plurality of sets of actuating units, each set of actuating units comprising a propeller arm, at least two pieces of propeller blades, a position limiter, and a driving motor controlled by a flight control system, the driving motor being connected to the end of the propeller arm, the driving motor driving the propeller blades to rotate forward or reverse, characterized in that, The propeller blades are hinged to the power output shaft of the drive motor. There are at least two limiters, which are installed on both sides of the propeller arm. The limiters form a folding space for at least two propeller blades. The limiters are located within the path of the propeller blades. When the propeller blades are folded, the limiters are pushed out toward the plane where the propeller blades are located.

2. A propeller folding mechanism for a foldable propeller according to claim 1, wherein: The limit switch is an electric push rod or a hydraulic push rod, and the extension and retraction of the electric push rod or hydraulic push rod are controlled by the flight control system.

3. A propeller folding mechanism for a foldable propeller according to claim 2, wherein: The limiters are arranged in a mirror image along the propeller arm axis.

4. A propeller folding mechanism for a foldable propeller according to claim 3, wherein: The distance from the farthest limit switch to the power output shaft of the drive motor is equal to the length of the propeller blade.

5. A propeller folding mechanism for a foldable propeller according to claim 2, 3 or 4, wherein: The extendable part of the electric actuator is a blocking component. When the propeller blades are folded, the height of the blocking component is at least 0.1 cm greater than the plane of the propeller blades.

6. The propeller folding mechanism for a foldable propeller according to claim 5, characterized in that: The blocking element is made of one or more flexible materials selected from silicone, polyurethane, thermoplastic elastomers, and foamed materials, and its hardness is less than 90HA.

Images