A propeller and mobile robot

Abstract

This invention relates to the technical field of propellers, and more specifically, to a propeller and a mobile robot. The propeller includes a shaft and blades. The blades include a first blade, a second blade, and a wingtip. One end of the first blade is fixedly connected to the shaft, and the other end is rotatably connected to one end of the second blade via a first rotating structure. The other end of the second blade is rotatably connected to the wingtip via a second rotating structure. The axis of rotation of the first rotating structure is a first axis, and the axis of rotation of the second rotating structure is a second axis, which intersect. The second blade rotates relative to the first blade around the first axis, and the wingtip rotates relative to the second blade around the second axis, allowing the propeller to switch between a folded state and an unfolded state. The solution of this invention, after completing the medium crossing from air to water, can reduce the resistance experienced by the blades in the water, improve the motor's working efficiency, avoid the motor operating in an unhealthy state with low efficiency, and extend the motor's service life.

Description

Technical Field

[0001] This invention relates to the technical field of propellers, and more specifically, to a propeller and a mobile robot. Background Technology

[0002] Propeller thrusters are a common type of drive device, widely used in the propulsion of aerial and underwater mobile robots. Due to the different working media, air propellers and water propellers have different structural features. Air propellers have straight and slender blades with fewer blades, designed to push a larger range of air when rotating at high speeds. Water propellers have wider blades with more blades, and the blades have a backward-curved shape to counteract the high resistance brought by water flow.

[0003] Currently, driven by demands such as shallow water exploration and near-shore aquaculture, mobile robots capable of operating in both water and air have become a hot research topic. Existing research primarily uses propellers as the main driving mechanism for these robots. However, due to the significant difference in propeller shape between the two media, the increased resistance experienced by an air-operated propeller during rotation after entering water leads to a substantial increase in the torque of the drive motor. In this case, the drive motor needs to operate at a much lower speed than the propeller would in the air to propel it in the water. According to the BET (Blade Element Theory), the motor efficiency η can be approximated as a function of the output torque τ and the rotational speed ω as follows:

[0004]

[0005] Where η is the motor efficiency; k v k τ The back electromotive force constant and torque constant of the motor satisfy the relationship k v ≥k τ ;R a τ is the winding resistance; τ0 is the motor's no-load torque; τ is the output torque; ω is the rotational speed; V s It is the power supply voltage.

[0006] As can be seen from the functional relationship between motor efficiency η and output torque τ and speed ω, motor efficiency first increases rapidly and then decreases slowly with the increase of output torque, and the motor has higher efficiency in the higher speed range.

[0007] When a propeller in the current technology enters the water, the increased resistance causes the motor speed to decrease. This decrease in motor speed puts the motor in an unhealthy operating state with low efficiency. If the motor is in an unhealthy operating state with low efficiency for a long time, it will not only increase energy consumption, but also affect the service life of the motor and increase the risk of motor damage. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing technologies where the increased resistance after the propeller enters the water leads to a decrease in motor speed, resulting in an unhealthy operating state of low motor efficiency. This invention provides a propeller and mobile robot in which the propeller can reduce its resistance during underwater movement, improve motor speed and efficiency, and avoid the motor being in an unhealthy operating state of low efficiency.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0010] A propeller is provided, comprising a propeller shaft and blades mounted on the propeller shaft. The blades are arranged equidistantly in a circle with the axis of the propeller shaft as the center. Each blade includes a first blade, a second blade, and a wingtip. One end of the first blade is fixedly connected to the propeller shaft, and the other end is rotatably connected to one end of the second blade via a first rotating structure. The other end of the second blade is rotatably connected to the wingtip via a second rotating structure. The axis of rotation of the first rotating structure is a first axis L1, and the axis of rotation of the second rotating structure is a second axis L2. The first axis L1 and the second axis L2 intersect. The second blade rotates relative to the first blade around the first axis L1, and the wingtip rotates relative to the second blade around the second axis L2, causing the propeller's operating state to switch between a folded state and an unfolded state.

[0011] When a propeller operates in a low-resistance medium such as the air, during the rotation of the propeller, the centrifugal force of the second blade is much greater than the drag on the second blade, and the centrifugal force of the wingtip is also much greater than the drag on the wingtip. Under the action of centrifugal force, the axes w of the first blade, the second blade and the wingtip coincide, making the blade as a whole straight, which is the deployed state of the propeller.

[0012] When a propeller operates in a high-resistance medium such as water, during rotation, the second blade folds onto the first blade after rotating around the first axis L1 via the first rotating structure. The wingtip rotates around the second axis L2 via the second rotating structure until it reaches a balanced state; this is the folded state of the propeller. In the folded state, the first axis L1 and the second axis L2 can intersect in the same plane or in opposite planes, with the included angle ranging from 0° to 90°.

[0013] Specifically, when the propeller operates in a high-resistance medium such as water, the centrifugal force of the second blade is less than the resistance it experiences. Under the influence of this resistance, the second blade rotates around the first axis L1 via the first rotating structure and folds onto the first blade. At this point, the axis m of the first blade intersects the axis n of the second blade, and the angle between them is the folding angle, which ranges from 0 to 90°. When the second blade folds onto the first blade, the second and first blades are on the same plane of rotation. That is, along the direction of the propeller shaft axis, the projection line segment formed by the width of the second blade on the propeller shaft axis is within the projection line segment formed by the width of the first blade on the propeller shaft axis, thus reducing the resistance experienced by the second blade during rotation.

[0014] When the propeller operates in a high-resistance medium such as water, the centrifugal force at the wingtip is less than the drag it experiences. Simultaneously, as the propeller moves through the high-resistance medium, the resulting vortices create a pressure difference between the upper and lower sides of the wingtip. Under the combined effect of centrifugal force, drag, and pressure difference, the wingtip rotates around the second axis L2 on the second blade via a second rotating structure. When the wingtip reaches equilibrium, its axis w intersects with the axis n of the second blade. At this point, the wingtip is tilted upwards on the second blade, effectively preventing the medium from flowing out of the blade tip and reducing the influence of the vortices.

[0015] The propeller of this invention remains deployed during airborne motion, providing the lift required for flight. When traversing from low-resistance media such as air to high-resistance media such as water, the blades can switch from deployed to folded. The folded blades have a backward-curved shape to counteract the high drag of high-resistance media such as water. Simultaneously, the second blade, even after folding, remains on the same plane of rotation as the first blade, further reducing drag. Furthermore, the raised wingtips of the folded blades effectively prevent media from flowing out of the blade tips, reducing the influence of wingtip vortices. With reduced drag during blade rotation, the motor driving the blades can increase its rotational speed, thereby improving motor efficiency. This ensures the motor operates at high efficiency, avoiding unhealthy low-efficiency operation and extending its lifespan. This technology is beneficial for the development of small, miniature water-to-air cross-medium mobile robots with limited load and energy.

[0016] Furthermore, the position of the first axis L1 is determined through the following steps:

[0017] A coordinate system is established with the center of the propeller shaft as the origin, the direction of the propeller blade as the positive x-axis, the direction of propeller rotation as the positive y-axis, and the vertically upward direction as the positive z-axis.

[0018] The center of the first axis L1 is [l1,0,0], where l1 is the length of the first blade;

[0019] The direction of the first axis L1 Calculated using the following formula:

[0020]

[0021] Where α is the folding angle between the first blade and the second blade when the propeller is in a folded state; θ is the propeller pitch angle.

[0022] After determining the position of the first axis L1 using the above method, the second blade folded onto the first blade remains on the same plane of rotation as the first blade when rotating. At this time, the angle between the blade surface of the second blade and the horizontal plane becomes smaller, the overall length of the blade decreases, and the pitch angle of the blade also decreases. The outermost edge of the second blade is almost folded with the horizontal plane, thereby reducing the resistance when the second blade rotates, thus reducing the resistance experienced by the propeller during rotation and reducing the risk of propeller damage.

[0023] Furthermore, the position of the second axis L2 is determined through the following steps:

[0024] When the second blade on the propeller is in a folded state and the wingtip is in a deployed state, obtain the position of the wingtip at this time;

[0025] When both the second blade and the wingtip on the propeller are in a folded state, the rotation direction of the wingtip is determined according to the first direction k, wherein the first direction k is: the direction of the line connecting the intersection of the wingtip axis w and the second blade axis n with the center point of the propeller shaft when the second blade on the propeller is in a folded state and the wingtip begins to rotate through the second rotating structure, and the rotation direction of the wingtip is perpendicular to the first direction k;

[0026] A tangent is drawn along the rotation direction of the wingtip, and this tangent is projected onto the second blade. The projected position is the position of the second axis L2.

[0027] After determining the position of the second axis L2 using the above method, when the propeller rotates in a high-drag medium such as water, the wingtip can rotate around the second axis L2, forming a structure similar to the winglet at the end of a fixed-wing aircraft wing. This effectively blocks the medium from flowing out of the blade tip, reducing the influence of wingtip vortices. Furthermore, the wingtip automatically adjusts its rotation angle based on the pressure difference to achieve equilibrium. After reaching equilibrium, the wingtip will not completely fold onto the second part; therefore, the range of the wingtip rotation angle β is 180° > β > 0. The wingtip can rotate clockwise or counterclockwise around the second axis L2, meaning it can rotate upwards or downwards on the second blade. Under normal conditions, upward rotation of the wingtip effectively blocks the medium from flowing out of the blade tip, reducing the influence of vortices. However, downward rotation of the wingtip also effectively blocks the medium from flowing out of the blade tip, reducing the influence of vortices. For example, the wingtip of the German He 162 aircraft is designed with a downward-curving shape to reduce the influence of vortices on the wing. The direction of wingtip rotation depends on the specific force conditions acting on the wingtip.

[0028] Furthermore, the first rotating structure includes a first boss on the first blade, a second boss on the second blade, and a first rotating shaft passing through the first boss and the second boss, both of which are rotatably connected to the first rotating shaft. Since the first axis L1 does not coincide with the plane containing the first and second blades, the presence of the first and second bosses increases the contact area between the first and second blades and the first rotating shaft, making the connection between the first and second blades and the first rotating shaft more robust.

[0029] Furthermore, the first protrusion is provided with a first limiting surface, and the second protrusion is provided with a second limiting surface. When the second blade is in the folded state, the first limiting surface abuts against the second limiting surface. The first protrusion is also provided with a third limiting surface, and the second protrusion is also provided with a fourth limiting surface. When the second blade is in the unfolded state, the third limiting surface abuts against the fourth limiting surface. By using four limiting surfaces to abut against each other in pairs, the second blade in the folded and unfolded states is limited, thus achieving a good limiting effect. In addition to using the limiting surface abutment method to limit the rotation angle of the second blade, a damping shaft or a limiting structure at the rotational speed can also be used to limit the rotation angle of the second blade. The rotation angle of the second blade is the folding angle α.

[0030] Furthermore, the second rotating structure includes a first connecting portion located on the end face of the second blade, a second connecting portion located on the wingtip face, and a second rotating shaft passing through the first connecting portion and the second connecting portion. Both the first connecting portion and the second connecting portion are rotatably connected to the second rotating shaft. The first connecting portion and the second connecting portion are located at the ends of the second blade and the wingtip, respectively, so that the blade does not generate additional drag in other directions when rotating.

[0031] Furthermore, the second blade includes multiple blades connected sequentially, with adjacent blades rotatably connected via a third pivot. Two blades at the beginning and end are respectively connected to the first blade and the wingtip. When the second blade is in its deployed state, the axes of the multiple blades coincide, making the blade's axis straight. When the second blade is in its folded state, adjacent blades fold at a small angle, achieving the effect of multiple blades folding backwards in segments. In this case, the blade's axis is a multi-segmented zigzag shape, similar to the axis of a traditional underwater propeller blade. The folded blade more closely resembles the curved shape of a traditional underwater propeller blade. The blades are provided with a first limiting part and a second limiting part. When the second blade is in its deployed state, the first limiting part limits the blade; when the second blade is in its folded state, the second limiting part limits the blade.

[0032] Furthermore, the propeller has three blades. In conventional designs, air-operated propellers typically have fewer blades, usually two or three. Too many blades would increase the propeller's weight and make it inconvenient to carry and operate. Water-operated propellers, on the other hand, generally have three to five blades. To simultaneously meet the requirements for both air and water use, this design uses a propeller with three blades.

[0033] The present invention also provides a mobile robot, including a main body and a propeller thruster. The propeller thruster includes a drive motor and a propeller. The drive motor is fixedly mounted on the main body, and the propeller is rotatably connected to the main body. The output end of the drive motor is fixedly connected to the propeller shaft. The propeller is the aforementioned propeller.

[0034] The mobile robot of this invention can reduce the resistance experienced by the propeller after transitioning from a low-resistance medium such as air to a high-resistance medium such as water, thereby increasing the rotational speed of the drive motor in a high-resistance medium such as water, improving the working efficiency of the motor, and enabling the motor to always be in a high-efficiency working state, avoiding the motor being in an unhealthy operating state with low working efficiency, and extending the service life of the robot.

[0035] Furthermore, the propeller thruster also includes a gearbox, which is fixedly mounted on the main body. The output end of the drive motor is connected to the input end of the gearbox, and the output end of the gearbox is connected to the propeller shaft. The gearbox allows for further adjustment of the propeller speed, thereby improving the driving efficiency of the mobile robot, increasing its load capacity, and enabling the mobile robot to achieve efficient driving even under certain load conditions.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] The propeller of this invention remains deployed during airborne motion, providing the lift required for flight. When traversing from a low-resistance medium (air) to a high-resistance medium (water), the blades can switch from deployed to folded, reducing drag. Furthermore, the raised wingtips of the folded blades effectively prevent media from flowing out of the blade tips, reducing the impact of wingtip vortices. With reduced drag during blade rotation, the motor driving the blades can increase its rotational speed, thereby improving motor efficiency. This ensures the motor operates at high efficiency, avoiding unhealthy low-efficiency operation and extending its lifespan. This technology is beneficial for the development of small, miniature water-to-air cross-medium mobile robots with limited load and energy.

[0038] The second blade of a propeller according to the present invention includes multiple blades. When the second blade is in a folded state, two adjacent blades are folded at a small angle. The multiple blades have a segmented backward folding shape, so that the folded blade is closer to the curved shape of a traditional underwater propeller blade, resulting in less resistance when moving in a high-resistance medium such as water.

[0039] The mobile robot of this invention can reduce the resistance experienced by the propeller after transitioning from a low-resistance medium such as air to a high-resistance medium such as water, thereby increasing the rotational speed of the drive motor in a high-resistance medium such as water, improving the working efficiency of the motor, and enabling the motor to always be in a high-efficiency working state, avoiding the motor being in an unhealthy operating state with low working efficiency, and extending the service life of the robot. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a propeller in its deployed state.

[0041] Figure 2 This is a schematic diagram of a propeller in a folded state.

[0042] Figure 3 This is a schematic diagram of a propeller in a folded state at another angle.

[0043] Figure 4 A comparison chart of the speed-torque curves of a propeller and a traditional empty propeller in air and water, and the corresponding motor efficiencies.

[0044] Figure 5 For a type of propeller Figure 1 Enlarged view of part A in the image;

[0045] Figure 6 For a type of propeller Figure 2 Enlarged view of section C in the image;

[0046] Figure 7 For a type of propeller Figure 1 Enlarged view of part B in the image.

[0047] In the attached diagram: 1. Propeller shaft; 2. First propeller blade; 3. Second propeller blade; 4. Wingtip; 5. First rotating structure; 6. Second rotating structure; 501. First boss; 502. Second boss; 503. First pivot; 511. First limiting surface; 521. Second limiting surface; 512. Third limiting surface; 522. Fourth limiting surface; 601. First connecting part; 602. Second connecting part; 603. Second pivot. Detailed Implementation

[0048] The present invention will be further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only, representing schematic diagrams rather than actual physical objects, and should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0049] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0050] Example 1

[0051] This embodiment is a first embodiment of a propeller, such as Figure 1 and Figure 2As shown, the propeller includes a propeller shaft 1 and three blades mounted on the shaft 1. The three blades are arranged equidistantly in a circle with the axis of the propeller shaft 1 as the center. Each blade includes a first blade 2, a second blade 3, and a wingtip 4. One end of the first blade 2 is fixedly connected to the propeller shaft 1, and the other end is rotatably connected to one end of the second blade 3 via a first rotating structure 5. The other end of the second blade 3 is rotatably connected to the wingtip 4 via a second rotating structure 6. The axis of rotation of the first rotating structure 5 is the first axis L1, and the axis of rotation of the second rotating structure 6 is the second axis L2. The first axis L1 and the second axis L2 intersect in opposite planes. The rotation of the second blade 3 relative to the first blade 2 around the first axis L1 and the rotation of the wingtip 4 relative to the second blade 3 around the second axis L2 allow the propeller to switch between a folded state and an unfolded state. Figure 3 As shown, when the propeller is in a folded state, the first blade 2 and the second blade 3 are in the same plane of rotation.

[0052] Specifically, the position of the first axis L1 is determined through the following steps:

[0053] like Figure 1 and Figure 2 As shown, a coordinate system is established with the center of propeller shaft 1 as the origin of the coordinate system, the direction of the propeller blade as the positive x-axis, the direction of propeller rotation as the positive y-axis, and the vertically upward direction as the positive z-axis.

[0054] The center of the first axis L1 is [l1,0,0], where l1 is the length of the first blade 2;

[0055] Direction of the first axis L1 Calculated using the following formula:

[0056]

[0057] Where α is the folding angle between the first blade 2 and the second blade 3 when the propeller is in the folded state; θ is the propeller pitch angle.

[0058] Specifically, such as Figure 2 As shown, the position of the second axis L2 is determined in the following way:

[0059] When the second blade 3 on the propeller is in a folded state and the wingtip 4 is in an unfolded state, obtain the position of the wingtip 4 at this time.

[0060] When both the second blade 3 and the wingtip 4 on the propeller are in a folded state, the rotation direction of the wingtip 4 is determined according to the first direction k. The first direction k is the direction of the line connecting the intersection of the wingtip axis w and the second blade axis n with the center point of the propeller shaft 1 when the second blade 3 on the propeller is in a folded state and the wingtip 4 starts to rotate through the second screw connection structure 6. The rotation direction of the wingtip 4 is perpendicular to the first direction k.

[0061] Draw a tangent along the rotation direction of the wingtip 4 and project this tangent onto the second blade 3. The projected position is the position of the second axis L2.

[0062] The working principle and process of this embodiment are as follows:

[0063] like Figure 1 As shown, when the propeller operates in a low-resistance medium such as the air, during the rotation of the propeller, the centrifugal force of the second blade 3 is much greater than the resistance experienced by the second blade 3, and the centrifugal force of the wingtip 4 is also much greater than the resistance experienced by the wingtip 4. Under the action of centrifugal force, the axes of the first blade 2, the second blade 3 and the wingtip 4 coincide, making the blade as a whole straight, which is the propeller in the deployed state.

[0064] like Figure 2 As shown, when the propeller operates in a high-resistance medium such as water, during the rotation of the propeller, the second blade 3 is folded onto the first blade 2 after rotating around the first axis L1 via the first rotating structure 5. The wingtip 4 is rotated around the second axis L2 via the second rotating structure 6 to a balanced state. This is the folded state of the propeller. The first axis L1 and the second axis L2 can intersect in the same plane or in opposite planes, and the angle between them is in the range of 0-90°.

[0065] Specifically, when the propeller operates in a high-resistance medium such as water, the centrifugal force of the second blade 3 is less than the resistance experienced by the second blade 3. Under the action of the resistance, the second blade 3 rotates around the first axis L1 via the first rotating structure 5 and folds onto the first blade 2. At this time, the axis m of the first blade and the axis n of the second blade intersect, and the angle between them is the folding angle α, which ranges from 0 to 90°. Figure 3 As shown, when the second blade 3 is folded onto the first blade 2, the second blade 3 and the first blade 2 are on the same plane of rotation. That is, in the direction along the axis of the propeller shaft 1, the projection line segment formed by the width of the second blade 3 on the axis of the propeller shaft 1 is within the projection line segment formed by the width of the first blade 2 on the axis of the propeller shaft 1. The fact that the second blade 3 and the first blade 2 are on the same plane of rotation can further reduce the resistance encountered by the second blade 3 when rotating.

[0066] When the propeller operates in a high-drag medium such as water, the centrifugal force on the wingtip 4 is less than the drag it experiences. Simultaneously, as the propeller moves through the high-drag medium, the resulting vortex creates a pressure difference between the upper and lower sides of the wingtip 4. Under the combined action of centrifugal force, drag, and pressure difference, the wingtip 4 rotates around the second axis L2 on the second blade 3 via the second rotating structure 6. When the wingtip 4 reaches equilibrium, the wingtip axis w intersects with the second blade axis n. At this point, the wingtip 4 is tilted upwards on the second blade 3. Figure 2 As shown, this serves to prevent the medium from flowing out from the blade tip, reducing the impact of eddies.

[0067] The beneficial effects of this embodiment are as follows:

[0068] In this embodiment, the propeller remains deployed during airborne motion, providing the lift required for flight. When traversing from low-resistance media like air to high-resistance media like water, the blades can switch from deployed to folded. The folded blades have a backward-curving shape to counteract the high drag of the water flow. Furthermore, the second blade 3, even after folding, remains on the same plane of rotation as the first blade 2, further reducing drag. Additionally, the upturned wingtips 4 in the folded state effectively prevent media from flowing out of the blade tips, reducing the influence of wingtip vortices. With reduced drag during blade rotation, the motor driving the blades can increase its speed, thereby improving motor efficiency. This ensures the motor operates at high efficiency, avoiding unhealthy low-efficiency operation and extending its lifespan. This contributes to the development of small, miniature water-to-air cross-medium mobile robots with limited load and energy.

[0069] like Figure 4 As shown in the figure, the intersection of the blade curve and the motor speed curve represents the blade speed under the current motor voltage and working medium conditions. The points on the corresponding motor efficiency curve represent the motor efficiency at that time. Under the ideal maximum power output conditions of a DC motor, compared with a traditional empty propeller that cannot be folded, the propeller in this real-time example, with a motor voltage of 24V, as shown by points C and D in the figure, shows that the theoretical maximum speed that a traditional empty propeller can reach in water is 6545 RPM, requiring a driving torque of 1.05 N / m, at which point the motor efficiency is only 13.35%. As shown by points A and B in the figure, the propeller in this embodiment can reach a theoretical maximum speed of 14100 RPM under the same conditions, with a driving torque of 0.85 N / m, corresponding to a motor efficiency increase to 30.11%. The motor efficiency of the propeller in this embodiment is more than twice that of a traditional empty propeller motor.

[0070] Example 2

[0071] This embodiment is a second embodiment of a propeller. Based on the first embodiment, this embodiment further defines the structure of the propeller.

[0072] Specifically, such as Figure 5 and Figure 6 As shown, the first rotating structure 5 includes a first boss 501 on the first blade 2, a second boss 502 on the second blade 3, and a first rotating shaft 503 passing through the first boss 501 and the second boss 502. The first boss 501 and the second boss 502 are both rotatably connected to the first rotating shaft 503.

[0073] Specifically, such as Figure 5 and Figure 6 As shown, the first boss 501 is provided with a first limiting surface 511, and the second boss 502 is provided with a second limiting surface 521. When the second blade 3 is in a folded state, the first limiting surface 511 abuts against the second limiting surface 521. Figure 3 As shown, the first boss 501 is also provided with a third limiting surface 512, and the second boss 502 is also provided with a fourth limiting surface 522. When the second blade 3 is in the unfolded state, the third limiting surface 512 and the fourth limiting surface 522 abut against each other.

[0074] Specifically, such as Figure 7 As shown, the second rotating structure 6 includes a first connecting part 601 located on the end face of the second blade 3, a second connecting part 602 located on the end face of the wingtip 4, and a second rotating shaft 603 passing through the first connecting part 601 and the second connecting part 602. The first connecting part 601 and the second connecting part 602 are both rotatably connected to the second rotating shaft 603.

[0075] Specifically, the second blade 3 includes multiple blades connected sequentially. Adjacent blades are rotatably connected via a third shaft. The two blades at the front and rear ends are connected to the first blade 2 and the wingtip 4, respectively. Each blade has a first limiting part and a second limiting part. When the second blade 3 is in the deployed state, the first limiting part limits the blade; when the second blade 3 is in the folded state, the second limiting part limits the blade. The first limiting part is a fifth contact surface, and the second limiting part is a sixth contact surface. Both sides of the blade have a fifth and a sixth contact surface. Specifically, the fifth and sixth contact surfaces on the blade connected to the first blade 2, near the first blade 2, are the first limiting surface 511 and the third limiting surface 512, respectively. The method for determining the position of the third rotating shaft is similar to the method for determining the position of the first rotating shaft 503. After the positions of all the third rotating shafts are determined, the shape of the blades after all the blades are folded can be close to the curved shape of the blades of a traditional underwater propeller, and at this time the second blade 3 is still located on the same plane of rotation as the first blade 2.

[0076] The beneficial effects of this embodiment are as follows:

[0077] The first protrusion 501 and the second protrusion 502 increase the contact area between the first blade 2 and the second blade 3 and the first shaft 503, making the connection between the first blade 2 and the second blade 3 and the first shaft 503 more secure. The four limiting surfaces abut against each other in pairs to limit the second blade 3 in both folded and unfolded states, providing effective limiting. The first connecting part 601 and the second connecting part 602 are located at the ends of the second blade 3 and the wingtip 4, respectively, ensuring that the blades do not generate additional drag in other directions during rotation. The second blade 3 includes multiple blades. When the second blade 3 is in the folded state, adjacent blades fold at a small angle, and the multiple blades have a segmented, backward-folding shape, more closely resembling the curved shape of traditional underwater propeller blades, resulting in less drag underwater.

[0078] Example 3

[0079] This embodiment is an example of a mobile robot, including a main body and a propeller thruster. The propeller thruster includes a drive motor and a propeller. The drive motor is fixedly mounted on the main body, and the propeller is rotatably connected to the main body. The drive end of the drive motor is fixedly connected to the propeller shaft 1. The propeller is as described in Embodiment 1 or 2. When the robot switches between air and underwater movement, the speed of the drive motor remains constant.

[0080] Specifically, it also includes a gearbox, the input end of which is connected to the output end of the drive end, and the output end of the gearbox is connected to the propeller shaft 1.

[0081] The beneficial effects of this embodiment are as follows:

[0082] In this embodiment, the mobile robot does not need to change the speed of the propeller drive motor during the water-air medium conversion process, so that the drive motor always maintains a high-efficiency working state. At the same time, the propeller blades can automatically adjust their shape according to the changes in force, and the propeller can work efficiently under different medium conditions.

[0083] The mobile robot in this embodiment is also equipped with a gearbox, which can further control the propeller speed, thereby improving the driving efficiency of the mobile robot and increasing its load capacity, enabling the mobile robot to complete efficient driving even under a certain load.

[0084] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0085] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A propeller, comprising a propeller shaft (1) and blades mounted on the propeller shaft (1), wherein the blades are a plurality of blades arranged equidistantly in a circle with the axis of the propeller shaft (1) as the center, characterized in that, The propeller blades include a first blade (2), a second blade (3), and a wingtip (4). One end of the first blade (2) is fixedly connected to the propeller shaft (1), and the other end is rotatably connected to one end of the second blade (3) through a first rotating structure (5). The other end of the second blade (3) is rotatably connected to the wingtip (4) through a second rotating structure (6). The axis of rotation of the first rotating structure (5) is the first axis L1, and the axis of rotation of the second rotating structure (6) is the second axis L2. The first axis L1 and the second axis L2 intersect. The second blade (3) rotates relative to the first blade (2) around the first axis L1, and the wingtip (4) rotates relative to the second blade (3) around the second axis L2, so that the propeller working state switches between a folded state and an unfolded state.

2. A propeller according to claim 1, characterized in that, The position of the first axis L1 is determined through the following steps: A coordinate system is established with the center of the propeller shaft (1) as the origin of the coordinate system, the direction of the propeller blade as the positive x-axis, the rotation direction of the propeller as the positive y-axis, and the vertically upward direction as the positive z-axis. The center of the first axis L1 is [l1,0,0], where l1 is the length of the first blade (2); The direction of the first axis L1 Calculated using the following formula: Where α is the folding angle between the first blade (2) and the second blade (3) when the propeller is in a folded state; θ is the pitch angle of the propeller.

3. A propeller according to claim 2, characterized in that, The position of the second axis L2 is determined through the following steps: When the second blade (3) on the propeller is in a folded state and the wingtip (4) is in an unfolded state, obtain the position of the wingtip (4) at this time; When both the second blade (3) and the wingtip (4) on the propeller are in a folded state, the rotation direction of the wingtip (4) is determined according to the first direction k, wherein the first direction k is: the direction of the line connecting the intersection of the wingtip axis w and the second blade axis n with the center point of the propeller shaft (1) when the second blade (3) on the propeller is in a folded state and the wingtip (4) starts to rotate through the second rotating structure (6), and the rotation direction of the wingtip (4) is perpendicular to the first direction k; Draw a tangent along the rotation direction of the wingtip (4) and project the tangent onto the second blade (3). The projected position is the position of the second axis L2.

4. A propeller according to claim 2, characterized in that, The first rotating structure (5) includes a first boss (501) on the first blade (2), a second boss (502) on the second blade (3), and a first rotating shaft (503) passing through the first boss (501) and the second boss (502). The first boss (501) and the second boss (502) are both rotatably connected to the first rotating shaft (503).

5. A propeller according to claim 4, characterized in that, The first boss (501) is provided with a first limiting surface (511), and the second boss (502) is provided with a second limiting surface (521). When the second blade (3) is in a folded state, the first limiting surface (511) abuts against the second limiting surface (521).

6. A propeller according to claim 4, characterized in that, The first boss (501) is also provided with a third limiting surface (512), and the second boss (502) is also provided with a fourth limiting surface (522). When the second blade (3) is in the unfolded state, the third limiting surface (512) abuts against the fourth limiting surface (522).

7. A propeller according to claim 3, characterized in that, The second rotating structure (6) includes a first connecting part (601) located on the end face of the second blade (3), a second connecting part (602) located on the end face of the wingtip (4), and a second rotating shaft (603) passing through the first connecting part (601) and the second connecting part (602). The first connecting part (601) and the second connecting part (602) are both rotatably connected to the second rotating shaft (603).

8. A propeller according to any one of claims 2-7, characterized in that, The second blade (3) includes multiple blades connected in sequence. Adjacent blades are rotatably connected by a third shaft. The two blades located at the beginning and end are respectively connected to the first blade (2) and the wingtip (4).

9. A mobile robot, characterized in that, The device includes a main body and a propeller thruster. The propeller thruster includes a drive motor and a propeller. The drive motor is fixedly mounted on the main body. The propeller is rotatably connected to the main body. The output end of the drive motor is connected to the propeller shaft (1). The propeller is a propeller as described in any one of claims 1-8.

10. A mobile robot according to claim 9, characterized in that, The propeller also includes a gearbox, which is fixedly mounted on the main body. The output end of the drive motor is connected to the input end of the gearbox, and the output end of the gearbox is connected to the propeller shaft (1).

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