A longitudinally foldable water-air dual propeller

Abstract

The application discloses a longitudinally foldable water-air dual-purpose propeller, and belongs to the technical field of cross-medium aircraft propulsion, comprising a new-configuration hub, a longitudinal folding mechanism, a limiting structure and a down-bending propeller blade with a preset down-bending angle; the configuration of the propeller enables the down-bending propeller blade to be completely unfolded to form a first working configuration through centrifugal force in air, and the down-bending propeller blade to be passively folded and limited to form a second working configuration through hydrodynamic lift in water; the longitudinally foldable water-air dual-purpose propeller can automatically complete mode switching according to the difference between working media without any active control mechanism, and can maintain high efficient propulsion performance in both media.

Description

Technical Field

[0001] This invention belongs to the field of cross-medium aircraft propulsion technology, and in particular relates to a longitudinally foldable water-air dual-purpose propeller. Background Technology

[0002] In the face of future maritime competition demands, traditional single-medium platforms such as aircraft and submarines are showing limitations when performing multi-domain missions. Aircraft have inherent weaknesses in underwater detection and combat, making stealthy approach and sustained operation difficult; while submarines have limited mission radius and insufficient maneuverability, hindering rapid response to cross-domain mission requirements. Therefore, propulsion systems capable of efficient propulsion in both air and water environments are increasingly becoming a research focus for cross-medium aircraft capable of rapid air-to-water switching. The aerodynamic and hydrodynamic performance of the propeller is crucial to the overall energy efficiency, stability, and mission adaptability of the aircraft.

[0003] Air-based propellers have large diameters, and when rotating in water, the increased density of water increases rotational resistance, resulting in excessive torque on the drive unit and consequently, low propeller speed and significantly reduced thrust in the water. Conversely, water-based propellers have small diameters, requiring excessively high speeds to maintain thrust in the air, leading to excessive load on the propeller disk and low propeller efficiency. In summary, existing propellers are insufficient for dual-purpose (air and water) applications, making the development of a dual-purpose (air and water) propeller with both air and water propulsion efficiency of great significance.

[0004] Existing dual-purpose propulsion devices typically employ two types of solutions: one is to use different propulsion mechanisms in the air and water, such as separate propellers for air and water, which operate separately through folding or switching. However, this approach is complex, increases weight, and has high system redundancy. The other approach uses a fixed-shape composite propeller, attempting to balance aerodynamic and hydrodynamic requirements. However, due to the high density and load of the water environment, the propeller blades are prone to overload, insufficient thrust, or increased vibration when operating in water, making it difficult to accommodate the performance differences between the two media.

[0005] While some existing folding propeller blades can automatically unfold in air using centrifugal force, most can only achieve unidirectional folding within a plane, making them unable to adapt to the axial hydrodynamic lift exerted by high-density media underwater. When operating in water, these blades still experience significant energy loss due to accumulated axial drag, easily leading to stress concentration in the blade structure and affecting reliability. Therefore, there is considerable room for development in current amphibious propeller design to enable propeller blades to automatically adjust their attitude, reduce drag, and achieve stable propulsion in response to fluid loads underwater.

[0006] Therefore, there is an urgent need for a longitudinally foldable amphibious propeller to solve the problems existing in the current technology. Summary of the Invention

[0007] The purpose of this invention is to provide a longitudinally foldable propeller for both water and air use. It can automatically reduce the diameter of the propeller disk in water, reduce resistance, and avoid motor overload, while maintaining normal deployment and providing efficient thrust in air. The designed propeller can complete adaptive switching between air and water media without the need for an active actuator, thereby reducing system complexity and structural weight.

[0008] To achieve the above objectives, the present invention provides a longitudinally foldable amphibious propeller, comprising:

[0009] A new type of propeller hub is used for fixed connection with the motor output shaft;

[0010] A longitudinal folding mechanism is connected to the new configuration propeller hub;

[0011] A limiting structure is installed on the new configuration propeller hub;

[0012] The downward-curved propeller blades are connected to the new configuration hub at their roots via a longitudinal folding mechanism, providing the downward-curved propeller blades with folding freedom along the motor axis; the downward-curved propeller blades have a preset downward curvature angle.

[0013] The propeller is configured to form a first working configuration in an air medium and a second working configuration in a water medium.

[0014] Preferably, in the first working configuration, the propeller is configured such that the centrifugal force acting on the downward-curved propeller blades is greater than the aerodynamic force, driving the downward-curved propeller blades to fully unfold and remain in the same plane as the plane of rotation.

[0015] Preferably, in the second working configuration, the propeller is configured such that the hydrodynamic lift acting on the downward-curved propeller blades is greater than the centrifugal force, causing the downward-curved propeller blades to passively fold along the motor axis. When the passive folding produces an upward dihedral angle... When the angle reaches 50°–75°, it is blocked by the limiting structure, preventing the downward-curving propeller blades from folding further to the vertical position.

[0016] Preferably, in the second working configuration, the downward bend angle and the upward dihedral angle of the downward-bent propeller blades work together to ensure that the downward-bent propeller blades still have an effective water-facing area, thereby maintaining the ability to generate forward thrust.

[0017] Preferably, the preset downward bend angle of the downward-curved propeller blades The range is 20°–50°.

[0018] Preferably, the limiting structure is a limiting block, limiting boss, or limiting end face set on the new configuration propeller hub, and its position and shape are designed according to the required limiting upper dihedral angle.

[0019] Preferably, when the working medium is switched from water to air, as the aircraft leaves the water surface, the hydrodynamic lift disappears, and the downward-curved propeller blades automatically swing back from the second working configuration to the first working configuration under the action of centrifugal force; when the working medium is switched from air to water, as the aircraft enters the water, the hydrodynamic lift increases and becomes dominant, and the downward-curved propeller blades automatically fold from the first working configuration to the second working configuration; the entire switching process is passively driven by changes in hydrodynamics.

[0020] Preferably, in the second working configuration, the effective disk diameter of the propeller is reduced by 20% to 40% compared to the disk diameter in the first working configuration.

[0021] Therefore, the present invention employs the above-mentioned longitudinally foldable water-air dual-purpose propeller, which has the following beneficial effects:

[0022] (1) Through reasonable structural configuration, the propeller can automatically form two optimized working configurations in air and water, and achieve medium adaptation entirely by physical principles, avoiding the problems of high failure rate and high maintenance cost caused by the complex structure of traditional cross-medium platforms;

[0023] (2) In the first working configuration, the large diameter is maintained to achieve the best aerodynamic efficiency; in the second working configuration, the diameter is reduced by limited folding to reduce water resistance torque, while maintaining effective thrust. After the blades are automatically folded in the water, the water-facing area is significantly reduced, and the projected area and diameter are reduced, greatly reducing the hydrodynamic torque load. This can effectively avoid the problems of motor overload, thrust attenuation or inability to propel in water that occur with traditional fixed propellers, and significantly improve underwater propulsion efficiency.

[0024] (3) The adaptive function is realized entirely through mechanical structure, without the need for electrical control system, which significantly improves the reliability, environmental tolerance and service life of the system; the blade has self-protection capability, and in high impact water flow, the blade can automatically avoid high load, reduce structural damage caused by bending, fatigue or impact, and extend the life of blade and motor bearing.

[0025] (4) The unique limiting structure and downward-curved propeller blade combination design ensures that effective forward thrust can still be maintained in the folded state in the water, solving the problem of thrust loss in traditional folding propellers.

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the novel configuration of the propeller hub and the longitudinal folding mechanism according to an embodiment of the present invention;

[0028] Figure 2This is a schematic diagram of the longitudinally passively foldable water-air dual-purpose propeller under air conditions, showing the structure from the upper and lower isometric perspectives of an embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram of the longitudinally passively foldable water-air dual-purpose propeller under water conditions, showing the upper and lower isometric perspective view of the structure in an embodiment of the present invention.

[0030] Figure 4 This is a front view of the longitudinally passively foldable amphibious propeller of the present invention in underwater operation.

[0031] Figure 5 This is a schematic diagram of the longitudinally passively foldable water-air dual-purpose propeller in water operation according to an embodiment of the present invention.

[0032] Figure 6 This is a schematic diagram of the downward-curved propeller blade according to an embodiment of the present invention;

[0033] Reference numerals: 1. Longitudinal folding mechanism; 2. Limiting structure; 3. New configuration propeller hub; 4. Downward-curved propeller blade. Detailed Implementation

[0034] The following detailed description of embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0035] Please see Figures 1-6 A longitudinally foldable amphibious propeller, comprising:

[0036] The new configuration of the propeller hub 3 is used for fixed connection with the motor output shaft;

[0037] The longitudinal folding mechanism 1 is connected to the new configuration propeller hub 3;

[0038] The limiting structure 2 is set on the new configuration propeller hub 3; specifically, it is a limiting block, limiting boss or limiting end face set on the new configuration propeller hub 3, and its position and shape are designed according to the required limiting upper dihedral angle.

[0039] The downward-curved propeller blade 4 has its root connected to the newly configured hub 3 via a longitudinal folding mechanism 1, providing the downward-curved propeller blade 4 with a degree of folding freedom along the motor axis; the downward-curved propeller blade 4 has a preset downward curvature angle, and the preset downward curvature angle of the downward-curved propeller blade 4... For 20°–50° Figure 6 As shown, the preset downward bend angle is... It is 25°.

[0040] The propeller is configured to form a first working configuration in an air medium and a second working configuration in a water medium;

[0041] like Figure 2 As shown, in the first working configuration, the propeller is configured such that the centrifugal force acting on the downward-curved propeller blade 4 is greater than the aerodynamic force, driving the downward-curved propeller blade 4 to fully unfold. Due to the low air density and drag, the longitudinal fluid load acting on the downward-curved propeller blade 4 is far insufficient to drive the longitudinal folding mechanism 1, so it does not fold longitudinally, and the limiting structure 2 does not participate in the operation. The downward-curved propeller blade 4 automatically unfolds under the action of centrifugal force and is held in the same plane, forming a stable aerodynamic working shape. At this time, the downward-curved propeller blade 4 can output normal thrust without affecting flight performance.

[0042] like Figure 3 and Figure 4 As shown, in the second working configuration, the propeller is configured such that the hydrodynamic lift acting on the downward-curved propeller blade 4 is greater than the centrifugal force, pushing the downward-curved propeller blade 4 to passively fold along the motor axis. When the upward diagonal angle generated by the passive folding... When the angle reaches 50°–75°, it is blocked by the limiting structure 2, preventing the downward-curved propeller blade 4 from folding further to a vertical position, thus avoiding insufficient effective thrust. This folding configuration reduces the propeller disk diameter, decreases water drag torque and peak load, allowing the motor to operate stably with lower torque in water, improving underwater propulsion efficiency and reliability. The folded downward-curved propeller blade 4 also prevents motor overload in water, reduces damage to the blade due to fluid impact, and improves underwater propulsion efficiency and stability. The entire folding process requires no electronic control device or mechanical actuator, relying entirely on hydrodynamic adaptation. Figure 5 As shown, the upper reverse angle The angle is limited to 75°. In the second working configuration, the downward bend angle of the downward-curved propeller blade 4 works together with the upward dihedral angle to ensure that the downward-curved propeller blade 4 still has an effective water-facing area, thereby maintaining the ability to generate forward thrust.

[0043] When the working medium changes from water to air, as the aircraft leaves the water, the hydrodynamic force drops sharply, and centrifugal force regains dominance, causing the downward-curved propeller blades 4 to automatically return to their flat, air-deployed state. This automatic switching between water-folded and air-deployed media is achieved without any active mechanism. Under centrifugal force, the downward-curved propeller blades 4 automatically swing back from the second working configuration to the first working configuration. When the working medium changes from air to water, as the aircraft enters the water, the hydrodynamic lift increases and becomes dominant, causing the downward-curved propeller blades 4 to automatically fold from the first working configuration to the second working configuration. The entire switching process is passively driven by changes in hydrodynamics. In the second working configuration, the effective disk diameter of the propeller is reduced by 20% to 40% compared to the disk diameter in the first working configuration.

[0044] Example

[0045] Taking a cross-medium UAV as an example, this UAV uses a longitudinally foldable water-air amphibious propeller of this invention. The diameter of the propeller disk in water is 70% of that in air, and the motor speed in the air is tens of times higher than in water, taking 30 times as an example. The centrifugal force in the air is about 1000 times that in water, and the hydrodynamic lift experienced by the water-air amphibious propeller in water is about 5 times the centrifugal force. This water-air amphibious propeller can form a first working configuration in the air medium under the influence of centrifugal force, and a second working configuration in the water medium under the influence of hydrodynamic lift.

[0046] Therefore, this invention employs a longitudinally foldable amphibious propeller, comprising a novel hub configuration, a longitudinal folding mechanism, a limiting structure, and downward-curved propeller blades with a preset downward bend angle. The core design principle utilizes the significant difference in hydrodynamic characteristics between air and water to achieve passive switching of the downward-curved propeller blade's working configuration. When operating in air, the centrifugal force generated by the high-speed rotation of the motor dominates. This force is sufficient to overcome the restoring torque caused by the downward bend angle of the propeller blades themselves, completely unfolding and stabilizing all blades in a horizontal plane of rotation, forming the first unfolded working configuration. At this point, the propeller disk area is at its maximum, achieving efficient aerodynamic propulsion. When entering water, the high density of the water causes a sharp increase in hydrodynamic lift, which replaces centrifugal force as the dominant force. This lift drives the downward-curved propeller blades to passively fold upstream around the longitudinal folding mechanism. During this process, the preset downward bend angle of the propeller blades couples with the folding motion, jointly adjusting the blade attitude. The folding angle is strictly limited by the limiting structure fixed on the hub of the new configuration. When the dihedral angle of the downward-curving propeller blade reaches 50°–75°, it is blocked, forming a stable second working configuration. In this configuration, the diameter of the propeller disk is significantly reduced, effectively reducing the drag torque and motor load in the water. At the same time, the synergistic effect of the limited folding angle and the downward-curving angle of the blade ensures that the blade can still maintain the ability to generate forward thrust in the folded state. The entire process is triggered entirely by changes in the physical environment, realizing a fully automatic and purely mechanical switching between two optimized states: large-diameter deployment in the air and small-diameter limited folding in the water. This ingeniously solves the problem of balancing aerodynamic and hydrodynamic efficiency in a single propulsion system for cross-medium aircraft.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A longitudinally foldable water / air propeller, characterized in that, include: A new type of propeller hub is used for fixed connection with the motor output shaft; A longitudinal folding mechanism is connected to the new configuration propeller hub; A limiting structure is installed on the new configuration propeller hub; The downward-curved propeller blades are connected to the new configuration hub at their roots via a longitudinal folding mechanism, providing the downward-curved propeller blades with folding freedom along the motor axis; the downward-curved propeller blades have a preset downward curvature angle. The propeller is configured to form a first working configuration in an air medium and a second working configuration in a water medium; The propeller is configured such that the hydrodynamic lift acting on the downward-curved propeller blades is greater than the centrifugal force, causing the downward-curved propeller blades to passively fold along the motor shaft direction. The upward diagonal angle generated by this passive folding... When the angle reaches 50°–75°, it is blocked by the limiting structure, preventing the downward-curved propeller blades from folding further to the vertical position; In the second working configuration, the downward bend angle and the upward dihedral angle of the downward-bent propeller blades work together to ensure that the downward-bent propeller blades still have an effective water-facing area, thereby maintaining the ability to generate forward thrust. Preset downward bend angle of downward bend propeller blades The range is 20°–50°.

2. The longitudinally foldable dual-purpose (water and air) propeller according to claim 1, characterized in that: In the first working configuration, the propeller is configured such that the centrifugal force acting on the downward-curved propeller blades is greater than the aerodynamic lift, driving the downward-curved propeller blades to fully extend and remain in the same plane as the plane of rotation.

3. The longitudinally foldable dual-purpose water and air propeller according to claim 1, characterized in that: The limiting structure is a limiting block, limiting boss, or limiting end face set on the new configuration propeller hub. Its position and shape are designed according to the required upper dihedral angle.

4. The longitudinally foldable amphibious propeller according to claim 1, characterized in that: When the working medium is switched from water to air, as the aircraft leaves the water surface, the hydrodynamic lift disappears, and the downward-curved propeller blades automatically swing back from the second working configuration to the first working configuration under the action of centrifugal force; when the working medium is switched from air to water, as the aircraft enters the water, the hydrodynamic lift increases and becomes dominant, and the downward-curved propeller blades automatically fold from the first working configuration to the second working configuration; the entire switching process is passively driven by changes in hydrodynamics.

5. A longitudinally foldable amphibious propeller according to claim 1, characterized in that: In the second operating configuration, the effective disk diameter of the propeller is reduced by 20% to 40% compared to the disk diameter in the first operating configuration.

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