Shaftless rim propeller and use control method thereof

Abstract

The invention discloses a shaftless rim propeller and a use control method thereof, and belongs to the technical field of propellers. The thruster comprises a thruster body, and an eddy current stator, an eddy current rotor and a PCB motor stator which are coaxially arranged with the thruster body, the propeller body comprises a PCB motor rotor, the PCB motor rotor is provided with a cylindrical shell, an outer edge ring is arranged on the outer surface of the circumference of the cylindrical shell, the cylindrical shell is provided with two ports, one port serves as an inlet, the other port serves as an outlet, the inner side of the cylindrical shell is provided with a containing space, and a plurality of shaftless propeller blades are arranged in the containing space. The shaftless propeller blades face the inlet; a plurality of grooves are formed in the radial edge of the side, facing the inlet direction, of the outer edge ring, and permanent magnets are arranged in the grooves. The PCB motor stator is arranged on the cylindrical shell in a sleeving manner, and the PCB motor stator and the permanent magnet are oppositely arranged; the eddy current stator and the eddy current rotor are sequentially arranged on the cylindrical shell in a sleeving mode, and the eddy current rotor is attached to the other side face of the outer edge ring.

Description

Technical Field

[0001] This invention belongs to the field of propulsion technology, and more specifically, relates to a shaftless rim propulsion device and its control method, which can be applied to underwater robots, micro drones and industrial automation equipment. Background Technology

[0002] The first model of the shaftless rim-driven thruster was proposed by Kort in Germany in 1940, thus replacing the shafted thruster. The shaftless rim-driven thruster (RDT) adopts a structural design different from that of electric thrusters, integrating the motor and propeller into one unit. This compact integrated solution significantly reduces the space occupied by the thruster system in the ship's cabin, which is beneficial to improving propulsion efficiency and comfort, while also reducing vibration and noise of the propulsion system.

[0003] Currently, shaftless rim thrusters are mainly designed as an integrated unit of bearings, stator, rotor drive ring, and blades. The integrated motor thruster drives the shaftless rim thruster, and the blades are connected to the rotor through the rim. There is a gap between the stator and the rotor. When the motor coil is energized, the magnetic force drives the inner rotor to rotate. The rotor drives the blades to rotate, which in turn drives the fluid to move and forms a reverse thrust.

[0004] A search revealed that patent application CN119253962A discloses a shaftless rim-mounted thruster with axial magnetic flux. This thruster includes a housing, a rotor, and two annular stators. The rotor is located inside the housing and connected to it via a water-lubricated radial bearing. The two annular stators are located on either side of the rotor, and a water-lubricated thrust bearing is provided between the annular stators and the rotor. This structure reduces the axial dimension, balances the axial magnetic pull, and can provide greater torque output within the same volume.

[0005] Patent application CN105109650A discloses a counter-rotating shaftless rim-driven propeller. The propeller is equipped with a conduit assembly, and its housing cavity contains a stator winding, a front rotor assembly, and a rear rotor assembly. The rotor rings in the two rotor assemblies form a tapered pair in the axial direction. The permanent magnets embedded in the outer wall of the rotor rings have opposite polarities. When the stator windings are energized, they form a magnetic field with opposite magnetic properties to the permanent magnets, driving the dual rotors to rotate and forming a dual-rotor ring motor.

[0006] Patent application CN102632982A discloses a shaftless integrated motor propulsion device, which consists of three sections arranged in series on a solid non-rotating shaft: a front stator, a rotor propeller, and a rear stator. The outer periphery of the propeller blades is connected to an annular circumferential rim of the propeller, and the rotor permanent magnet is nested inside the circumferential rim of the propeller. The stator winding is provided in the inner cavity of the guide tube. Both the rotor permanent magnet and the stator winding are water-sealed, and a gap is provided between them to form an annular motor.

[0007] Patent application CN112478118A discloses a podded shaftless rim-driven integrated motor propulsion device. A permanent magnet motor stator and a permanent magnet motor rotor are installed inside the conduit. The outer end of the propeller is connected to the rotor support, and the inner end of the propeller is fixed to the central column. A water gap is set between the permanent magnet motor stator and the permanent magnet motor rotor to form a ring motor. Two sets of radial slat-type water-lubricated rubber alloy bearings are also set inside the conduit to support the rotor, and one set of axial slat-type water-lubricated rubber alloy bearings is set to bear the axial thrust.

[0008] Patent application CN112829913A discloses a high-thrust rim propeller, which includes a shaft, a housing, a motor stator and a motor rotor. The shaft is hollow and horn-shaped, and is movably mounted in the end caps on both sides of the housing via bearings. A propeller is fixedly mounted on the inner ring of the large end of the shaft, and a motor rotor is fixedly mounted on the outer ring of the small end. The motor stator is fixedly mounted on the housing and corresponds to the rotor.

[0009] However, while existing shaftless rim thrusters have solved some of the pain points of shafted thrusters, they still have the following problems: First, permanent magnet motors are large in size and weight, which is not conducive to the miniaturization and lightweight design of the thruster; second, due to the influence of winding process, stator and rotor materials, permanent magnet motors have low manufacturing precision and are relatively expensive, which increases the overall cost of the thruster. Summary of the Invention

[0010] 1. The problem to be solved To address the technical problems existing in the prior art, the present invention provides a shaftless rim propeller and its usage control method, which makes the propeller lightweight and highly efficient.

[0011] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides a shaftless rim propeller, comprising a propeller body and an eddy current stator, an eddy current rotor and a PCB motor stator coaxially disposed with the propeller body; The propulsion body includes a PCB motor rotor, which has a cylindrical shell. An outer ring is provided on the outer circumference of the cylindrical shell. The cylindrical shell has two ports, one of which serves as an inlet and the other as an outlet. The inner side of the cylindrical shell has an accommodating space, and a plurality of shaftless propeller blades (the blades are made of high-strength, corrosion-resistant metal materials, such as stainless steel or aluminum alloy) are arranged inside the accommodating space, with the shaftless propeller blades facing the inlet. A plurality of grooves are provided along the radial edge of the outer ring on one side facing the inlet direction, and permanent magnets are embedded in the grooves; The PCB motor stator is sleeved on the cylindrical shell and close to the outer ring surface where the permanent magnet is located, so that the PCB motor stator is located on one side of the permanent magnet. The eddy current stator and eddy current rotor are sequentially sleeved on the cylindrical shell, with the eddy current rotor in contact with the other side of the outer ring (where "in contact" can be understood as partial or complete surface-to-surface contact and fixation). The permanent magnet and eddy current rotor are mounted on the outer ring, and the heat generated during use can be transferred to the cylindrical shell. The heat on the shell is then carried away by the fluid, thereby achieving heat dissipation.

[0012] The overall working mode of the shaftless rim propeller of the present invention is as follows: current is supplied to the stator of the PCB motor, and the rotor of the PCB motor (in this invention, a permanent magnet is combined with the rotor of the PCB motor, and the two together form the PCB rotor structure) will rotate. The eddy current rotor is also combined with the rotor of the PCB motor and rotates together with the shaftless propeller blades. At this time, the relatively fixed eddy current stator will receive the electrical signal generated by the rotation of the eddy current rotor. The corresponding angle and angular velocity of the eddy current rotor can be calculated by the chip (the eddy current sensor has its own chip). The calculated speed is fed back to the current input terminal of the PCB stator to control the input speed, thereby achieving the purpose of precise control of the PCB motor.

[0013] In underwater thruster applications, PCB motors and eddy current sensors must employ effective and reliable sealing measures to prevent water intrusion that could cause the thruster to malfunction. Common sealing methods include O-ring static sealing and epoxy resin potting. O-ring sealing is simple in structure and low in cost; epoxy resin potting is robust and reliable, completely isolating the thruster from external water, but at the expense of the thruster's maintainability. Without sealing, external water will enter the thruster, causing abnormal conductivity between electronic components, leading to component burnout or power outages. Furthermore, electrolytes in the water can corrode wiring and components, resulting in poor circuit contact or open circuits. A well-designed honeycomb structure ensures the thruster's reliability during long-term underwater operation, while epoxy resin potting further suppresses vibration and noise from the PCB motor, thus extending the thruster's lifespan.

[0014] Among them, the eddy current sensor achieves non-contact detection through the principle of electromagnetic induction, avoiding contact with the PCB motor rotor and eliminating contact mechanical wear. It is especially suitable for the ultra-thin, high-speed structure of PCB motors (such as the speed of micro drone thrusters, which can reach 100,000 revolutions per minute).

[0015] In this invention, the eddy current stator, eddy current rotor, and PCB motor stator of the shaftless rim propeller are all fitted onto the PCB motor rotor, resulting in a smaller overall size, especially in thickness. While ensuring detection accuracy, the eddy current sensor of this invention can detect the axial / radial displacement (accuracy up to ±1μm), vibration (amplitude resolution 0.1μm), and rotational speed (error <0.1%) of the PCB motor rotor in real time. For example, in an underwater robot propulsion system, it can accurately feed back the minute offset of the shaftless propeller blade caused by water flow impact, ensuring stable power output.

[0016] Furthermore, the outer ring of the shaftless rim propeller of the present invention, when combined with the cylindrical shell, helps to reduce the unit area in the direction of movement, thereby minimizing fluid resistance.

[0017] According to any embodiment of the first aspect of the present invention, the outer rim ring is integrally formed with the cylindrical shell and is made of a high-strength, corrosion-resistant metal material, such as stainless steel or aluminum alloy. The outer rim ring is disposed off-center on the outer circumferential surface of the cylindrical shell and offset towards the outlet direction; the vertical line of the shaftless propeller blade and the outer rim ring are located in the same vertical plane. The offset distance is h, and the ratio of the offset distance h to the length L of the cylindrical shell is 1:8-12. This off-center arrangement makes the dynamic balance of the entire propeller tend to be optimal, thereby ensuring the stable operation of the propeller.

[0018] According to any embodiment of the first aspect of the present invention, the coil of the PCB motor stator is arranged correspondingly to the permanent magnet, such that the coil can generate a magnetic field that repels the magnetic field of the permanent magnet, thereby providing magnetic power for the rotation of the PCB motor rotor.

[0019] According to any embodiment of the first aspect of the present invention, the permanent magnet is embedded in the cylindrical shell in the manner of a Heilbeck magnetic circuit array, and the permanent magnet enhances the magnetic field strength on one side.

[0020] According to any embodiment of the first aspect of the present invention, a shielding layer is further included, the shielding layer being disposed between the eddy current rotor and the outer ring, for isolating the magnetic field of the permanent magnet and the magnetic field generated by the high-speed rotation of the PCB motor stator, thereby shielding external signal interference and ensuring the accuracy of sensor detection data.

[0021] According to any embodiment of the first aspect of the present invention, the shielding layer includes a shielding ring, which is made of tin-plated copper, copper, or aluminum foil, specifically: 1) Tinned copper wire braided mesh: woven from tinned copper wire, it has good conductivity and flexibility, can effectively shield electromagnetic interference, and can adapt to the use requirements of thrusters in complex environments.

[0022] 2) Copper wire shielding: It usually consists of a single layer of overlapping soft copper wire, or double layers of soft copper wire with gaps; the average overlap between copper wires is 15% of the width of the copper wire (nominal value), and the minimum overlap should not be less than 5%.

[0023] 3) Aluminum foil: It has good conductivity and reflectivity. When electromagnetic interference signals reach the surface of aluminum foil, part of them are reflected back, thereby achieving the shielding function; for example, a layer of aluminum foil is laminated on the surface of a polyester film as the base layer.

[0024] According to any embodiment of the first aspect of the present invention, a shielding layer is formed on the opposite side of the outer ring relative to the groove by a shielding material. The shielding material is a metal layer obtained by methods such as spraying electromagnetic shielding coatings, molten metal spraying, magnetron sputtering, electroplating, or chemical plating, which can effectively reduce the thickness of the shielding layer, thereby reducing the volume of the thruster; furthermore, it allows the PCB motor to form an ultra-thin structure, ensuring the axial stability of the thruster during high-speed rotation.

[0025] In any embodiment of the first aspect of the present invention, the permanent magnet is protected by a hull alloy sealing sleeve. Permanent magnets are susceptible to oxidation from water molecules and air in certain environments (especially underwater). Therefore, the hull alloy sealing sleeve effectively prevents problems caused by oxidation and extends the service life of the permanent magnet.

[0026] According to any embodiment of the first aspect of the present invention, the eddy current stator includes a signal generating section and a signal decoding section. The signal generating section includes an excitation coil, a receiving coil Cos, and a receiving coil Sin. The excitation coil is distributed on the outer ring of the PCB board, and the receiving coils Sin and Cos are alternately distributed on the top and bottom layers of the PCB board.

[0027] According to any embodiment of the first aspect of the present invention, in order to achieve a lightweight design of the module, the eddy current rotor adopts a PCB structure design, and a plurality of fan-shaped copper plates, aluminum plates or aluminum alloy plates are arranged on the annular PCB board.

[0028] According to any embodiment of the first aspect of the present invention, the fan-shaped copper plate, aluminum plate or aluminum alloy plate is fixed by adhesive.

[0029] According to any embodiment of the first aspect of the present invention, the inner and outer arc edges of the fan-shaped copper plate, aluminum plate, or aluminum alloy plate are both located inside the edge of the annular PCB board. The eddy current rotor has three or four identical blades with uniformly distributed angles, and the output signal can be accurately obtained through the uniformly distributed blades.

[0030] According to any embodiment of the first aspect of the invention, the plurality of grooves are square and distributed substantially concentrically around the central axis of the cylindrical shell. The magnetic field formed by the permanent magnet is a relatively complete circle, thereby enabling the PCB motor rotor to rotate smoothly relative to the PCB motor stator.

[0031] Since all fits have unavoidable gaps and tolerances, when arranged in a concentric circle, they may not be perfectly aligned. Therefore, it can also be described as "basically concentrically distributed".

[0032] According to any embodiment of the first aspect of the present invention, the permanent magnet is a neodymium iron boron magnet, a samarium cobalt magnet, an alnico magnet, or a ferrite magnet.

[0033] The second aspect of the present invention provides a method for controlling the use of the shaftless rim propeller described in the first aspect. The method includes the steps of: closed-loop feedback control of the PCB motor by real-time monitoring of the rotor position or speed and dynamic adjustment of the drive signal by the controller to achieve high-precision motion control of the shaftless rim propeller.

[0034] The closed-loop system includes an eddy current sensor, a control algorithm module (PID, FOC (Field Oriented Control)), and a drive circuit. The eddy current sensor feeds back the detected signal to the controller (such as an MCU (Micro Control Unit)), compares it with the target value, and generates a PWM (Pulse Width Modulation) signal to adjust the phase, frequency, or amplitude of the PCB motor winding current, thereby correcting the deviation. The above control method effectively improves the dynamic response, load disturbance resistance, and energy efficiency of the PCB motor, and is suitable for scenarios requiring precise positioning or stable speed.

[0035] 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The shaftless rim propeller of the present invention adopts a planar eddy current sensor to achieve a lightweight design. The propeller is mainly composed of a PCB motor rotor, blades and stator. The eddy current sensor works in conjunction with the PCB motor stator through a spiral winding to measure the propeller's rotation angle and speed information in real time. (2) The thruster of the present invention integrates an eddy current sensor. While inheriting the advantages of common shaftless rim thrusters, it uses a PCB motor instead of a drive motor, making the thruster lightweight and efficient. Under the same cross-sectional area, the precision wiring of the PCB (Printed Circuit Board) can significantly reduce the winding resistance and enable low-cost mass production. (3) The shaftless rim thruster of the present invention avoids mechanical wear through non-contact measurement, and the ultra-thin structure adapted to the PCB motor ensures the axial stability of the thruster when rotating at high speed. Attached Figure Description

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless specifically indicated, these drawings are intended only to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0037] Figure 1 This is an exploded structural diagram of the shaftless rim propeller of the present invention; Figure 2 This is a three-dimensional structural diagram of the shaftless rim propeller of the present invention; Figure 3 This is a front view schematic diagram of the PCB motor rotor of the present invention; Figure 4 This is a three-dimensional structural diagram of the PCB motor rotor of the present invention; Figure 5 for Figure 3 Sectional view along line AA; Figure 6 This is a schematic diagram of the rotor structure of the eddy current sensor of the present invention; Figure 7 The raw data collected by the eddy current sensor of the shaftless rim propeller of this invention; Figure 8 This is a sine and cosine signal envelope diagram of the shaftless rim propeller of the present invention; Figure 9 This is a solution angle diagram of the shaftless rim propeller of the present invention; Figure 10 This is a block diagram of the PCB motor closed-loop control of the present invention.

[0038] Explanation of reference numerals in the attached figures: 1. Eddy current stator; 2. Eddy current rotor; 21. Sector-shaped copper plate; 22. PCB board; 3. Shielding ring; 4. PCB motor rotor; 41. Cylindrical housing; 42. Outer ring; 43. Accommodation space; 44. Shaftless propeller blade; 45. Groove; 46. Vertical plumb line; 47. Central axis; 5. Permanent magnet; 6. PCB motor stator. Detailed Implementation

[0039] The following detailed description of exemplary embodiments of the invention is taken with reference to the accompanying drawings, which form part of the description and illustrate exemplary embodiments in which the invention may be practiced. While these exemplary embodiments have been described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be implemented and various changes may be made to the invention without departing from the spirit and scope thereof. The more detailed description of embodiments of the invention below is not intended to limit the scope of the claimed invention, but is merely illustrative and not restrictive of the description of the features and characteristics of the invention, to suggest the best mode for carrying out the invention, and is sufficient to enable those skilled in the art to practice the invention. Therefore, the scope of the invention is defined only by the appended claims.

[0040] The following detailed description and exemplary embodiments of the invention can be better understood in conjunction with the accompanying drawings, wherein the elements and features of the invention are identified by reference numerals.

[0041] Example 1 like Figure 1 and Figure 2 As shown, the shaftless rim-mounted thruster of this embodiment includes a thruster body, an eddy current stator 1, an eddy current rotor 2, and a PCB motor stator 6, all coaxially arranged with the thruster body. The assembled thruster requires sealing to ensure safe and stable operation in fluid conditions. Within the scope of this invention, the aforementioned coaxial arrangement is defined as the central axes 47 being on the same straight line. Wherein, in Figure 1 In the process, the propulsion body includes a PCB motor rotor 4, which has a cylindrical shell 41. An outer edge ring 42 is provided on the outer circumferential surface of the cylindrical shell 41. The outer edge ring 42 is integrally formed with the cylindrical shell 41. The cylindrical shell 41 has two ports. In a fluid environment, one port serves as a fluid inlet and the other port serves as a fluid outlet.

[0042] Based on the above advantages, the present invention can also expand related application scenarios and achieve miniaturized design, such as manufacturing thrusters with an outer diameter of less than 20mm for use in microrobots, such as 3mm diameter PCB motor thrusters for intravascular navigation, and the fluids include but are not limited to water and blood.

[0043] Combination Figure 3 As shown, the inner side of the cylindrical shell 41 is hollow, having an accommodating space 43. The accommodating space 43 has a circular cross-section, and a plurality of shaftless propeller blades 44 are disposed inside it. The number of shaftless propeller blades 44 can be three or four. Figure 3In the middle, four shaftless propeller blades 44 are fixed to the inner wall of the cylindrical housing 41, for example by welding. The shaftless propeller blades 44 face the inlet and can provide thrust for the movement of the propeller.

[0044] like Figure 3 , Figure 4 and Figure 5 As shown, a plurality of grooves 45 are provided along the radial edge of the outer ring 42 facing the inlet direction. The plurality of grooves 45 are square (e.g., rectangular) and are distributed concentrically around the central axis 47 of the cylindrical shell 41. Permanent magnets 5 are built into the grooves 45. The magnetic field formed by the permanent magnets 5 is a relatively complete circle, thereby enabling the PCB motor rotor 4 to rotate smoothly relative to the PCB motor stator 6.

[0045] Furthermore, the permanent magnet 5 is a neodymium iron boron magnet, a samarium cobalt magnet, an alnico magnet, or a ferrite magnet. These permanent magnets may oxidize with water molecules and air in certain environments (especially in water). Therefore, the permanent magnet 5 is protected by a husky alloy sealing sleeve to effectively avoid problems caused by oxidation and extend its service life.

[0046] In this embodiment, the PCB motor stator 6 is sleeved on the cylindrical housing 41 and close to the outer ring 42 where the permanent magnet 5 is located, so that the PCB motor stator 6 is located on one side of the permanent magnet 5, and there is a gap between the PCB motor stator 6 and the cylindrical housing 41, so that the PCB motor stator 6 can rotate relative to the cylindrical housing 41; the eddy current stator 1 and the eddy current rotor 2 are sequentially sleeved on the cylindrical housing 41, and the eddy current rotor 2 is in contact with the other side of the outer ring 42.

[0047] In other words, the PCB motor stator 6, the eddy current stator 1, and the eddy current rotor 2 are located on both sides of the outer ring 42, and the eddy current rotor 2 is spaced apart from the eddy current stator 1 and fitted onto the PCB motor rotor 4. Figure 1 The diagram is only for illustrative purposes and does not represent the actual gap size. The eddy current rotor 2 is in contact with and fixed to the outer ring 42, and the eddy current rotor 2 can rotate together with the PCB motor rotor 4.

[0048] The overall module working mode of the shaftless rim propeller of the present invention is as follows: current is supplied to the PCB motor stator 6, and the PCB motor rotor 4 (in this invention, the permanent magnet 5 is combined with the shaftless propeller blade 44, and the two together serve as the PCB rotor structure) rotates. The eddy current rotor 2 is also combined with the shaftless propeller blade 44 and rotates together with the shaftless propeller blade 44. At this time, the eddy current stator 1 will receive the electrical signal generated by the rotation of the eddy current rotor 2. The chip can calculate the corresponding rotor (shaftless propeller blade 44) angle and angular velocity. The calculated speed is fed back to the current input terminal of the PCB motor stator 6 to control the input speed and achieve the purpose of precise control.

[0049] The eddy current sensor, consisting of an eddy current stator 1 and an eddy current rotor 2, achieves non-contact detection through the principle of electromagnetic induction, avoiding direct contact with moving parts such as the PCB motor rotor 4 and propeller blades, thus eliminating contact mechanical wear. It is especially suitable for the ultra-thin, high-speed structure of PCB motors (such as the propulsion speed of micro UAVs, which can reach 100,000 rpm).

[0050] In addition, the aforementioned eddy current sensor can monitor the axial / radial displacement (accuracy up to ±1μm), vibration (amplitude resolution 0.1μm), and PCB motor speed (error <0.1%) of the PCB motor rotor 4 in real time. For example, in an underwater robot propulsion system, it can accurately reflect the slight displacement of the propeller blade caused by the impact of fluid (e.g., water), ensuring stable power output.

[0051] In this embodiment, the outer ring 42 is integrally formed with the cylindrical shell 41, for example, using a high-strength, lightweight aluminum alloy, thereby ensuring high bonding strength between the outer ring 42 and the cylindrical shell 41. The integral forming of the outer ring and the cylindrical shell helps to reduce the unit area in the direction of movement, thus minimizing fluid resistance. Figure 5 As shown, the outer edge ring 42 is disposed off-center on the outer circumferential surface of the cylindrical shell 41 and offset toward the outlet direction; the shaftless propeller blade 44 and the plumb line 46 of the outer edge ring 42 are located in the same vertical plane.

[0052] The aforementioned offset distance is h. Preferably, in this embodiment, the ratio of the offset distance h to the length of the cylindrical housing 41 is 1:10. This design not only provides installation space for the PCB motor stator, but also, the aforementioned non-centralized setting ensures that the dynamic balance of the entire thruster is optimized, thereby guaranteeing stable operation of the thruster. Dynamic balancing tests show good stability.

[0053] exist Figure 1 In this configuration, the coil of the PCB motor stator 6 is arranged correspondingly to the permanent magnet 5, so that the coil can generate a magnetic field that repels the magnetic field of the permanent magnet 5, thereby providing magnetic power for the rotation of the PCB motor rotor 4.

[0054] Extensive research has revealed that the magnetic fields of the permanent magnet 5 and the high-speed rotation of the PCB motor stator 6 (up to 100,000 rpm) can affect the signal output of the eddy current stator 1 and the eddy current rotor 2. Therefore, to isolate the magnetic fields generated by the high-speed rotation of the permanent magnet 5 and the PCB motor stator 6, a shielding layer is provided between the eddy current rotor 2 and the outer ring 42. The size of the shielding layer is selected based on whether it is a solid layer structure or a coated structure; the thickness of the shielding layer is not specifically limited. Extensive experiments have shown that the shielding layer reduces electromagnetic coupling interference and ensures the accuracy of the eddy current detection signal.

[0055] In this embodiment, the shielding layer mentioned above includes a shielding ring 3, which is made of tin-plated copper, copper, or aluminum foil. The shielding ring 3 is fixed to the cylindrical shell 41. Specifically, it adopts the following method: 1) Tinned copper wire braided mesh: woven from tinned copper wire, it has good conductivity and flexibility, can effectively shield electromagnetic interference, and can adapt to the use requirements of thrusters in complex environments.

[0056] 2) Copper wire shielding: It usually consists of a single layer of overlapping soft copper wire, or double layers of soft copper wire with gaps; the average overlap between copper wires is 15% of the width of the copper wire (nominal value), and the minimum overlap should not be less than 5%.

[0057] 3) Aluminum foil: It has good conductivity and reflectivity. When electromagnetic interference signals reach the surface of aluminum foil, part of them are reflected back, thereby achieving the shielding function; for example, a layer of aluminum foil is laminated on the surface of a polyester film as the base layer.

[0058] The eddy current stator 1 in this embodiment includes a signal generating section and a signal decoding section. The signal generating section includes an excitation coil, a receiving coil Cos, and a receiving coil Sin. The excitation coil is distributed on the outer ring of the PCB board, and the receiving coils Sin and Cos are alternately distributed on the top and bottom layers of the PCB board.

[0059] In this circuit, a high-frequency alternating current is passed through the excitation coil. When the rotor of the eddy current sensor rotates, due to the eddy current effect, the receiving coils SIN and COS will receive and output electrical signals. The output waveform of the receiving coil is as follows: Figure 7 As shown. The eddy current sensor module integrates a signal processing chip (commercially available product) that can calculate the envelope of sine and cosine signals, such as... Figure 8 As shown.

[0060] Then, by performing arctangent calculations on the sine and cosine signals, the angle and angular velocity information of the eddy current rotor 2 can be obtained, such as... Figure 9 As shown.

[0061] From the above Figure 7 , Figure 8 and Figure 9 As shown, when the eddy current sensor of the present invention is used in conjunction with the PCB motor, the signal output is stable, and the calculated eddy current rotor 2 has small fluctuations in angle and angular velocity, indicating good stability.

[0062] Furthermore, to achieve a lightweight design and enhance the angle signal or realize absolute position measurement, the eddy current rotor 2 adopts a PCB structure design. Several fan-shaped copper plates 21, aluminum plates, or aluminum alloy plates are arranged on the annular PCB board 22, preferably copper plates. The number of copper plates is three or four. Further, the fan-shaped copper plates 21 are fixed with adhesive. Figure 6 In this configuration, the inner and outer arc edges of the fan-shaped copper plate 21 are both located inside the edge of the annular PCB board 22. The copper plate has a certain thickness (greater than the skin depth at this frequency) to ensure that eddy currents can be effectively generated.

[0063] The design of this invention abandons the traditional mechanical shaft structure and drives the blade rotation through the electromagnetic coupling of permanent magnet 5 and coil, which significantly reduces weight and friction loss. The integration of the eddy current sensor not only improves measurement accuracy but also simplifies the overall structure, making it suitable for fields that are sensitive to space and weight, such as underwater robots or aerospace propulsion systems. The eddy current sensor is not affected by oil, dust, or water vapor (such as the seawater environment of underwater robots).

[0064] When the thruster operates, the PCB motor stator is energized, generating a magnetic field that interacts with the permanent magnet, driving the PCB motor rotor to rotate. The PCB motor rotor then drives the shaftless propeller blades to rotate, drawing fluid in from the inlet, accelerating it through the propeller blades, and expelling it from the outlet, thus generating thrust. Simultaneously, a position detection system composed of the eddy current stator and rotor monitors the thruster's speed and position in real time, providing feedback signals to the control system. The shielding layer effectively isolates magnetic field interference between different components, ensuring stable system operation.

[0065] This shaftless rim-mounted thruster eliminates the fluid resistance and energy loss associated with the central shaft of traditional thrusters by employing a shaftless propeller blade design, thereby improving propulsion efficiency. The outer ring design not only enhances structural strength but also optimizes hydrodynamic performance. The application of a Helbeck magnetic circuit array improves magnetic field utilization and enhances the thruster's dynamic performance. The introduction of an eddy current position detection system enables high-precision monitoring of the thruster's position and velocity, providing a foundation for intelligent control.

[0066] Example 2 This embodiment is basically the same as the structure of Embodiment 1. The difference is that in this embodiment, a shielding layer is formed by a shielding material on the other side of the outer ring 42 opposite to the groove 45. The shielding material is an electromagnetic shielding coating or a metal layer formed by methods such as metal melt spraying, magnetron sputtering, electroplating, and chemical plating. The thickness of the metal layer is about a few micrometers to a dozen micrometers, which can effectively reduce the thickness of the shielding layer, thereby reducing the volume of the thruster. In addition, it makes the PCB motor form an ultra-thin structure, ensuring the axial stability of the thruster when rotating at high speed.

[0067] The aforementioned electromagnetic shielding coating is made of silver, copper, styrene, or carbon; the metal layer is made of silver, copper, styrene, or aluminum.

[0068] Example 3 This embodiment is basically the same as the structure of embodiment 1. The difference is that in this embodiment, the permanent magnet 5 is embedded on the cylindrical shell 41 in the form of a Heilbeck magnetic circuit array. The permanent magnet 5 enhances the magnetic field strength on one side. The enhancement of the magnetic field strength can increase the interaction force between the rotor and stator of the PCB motor, so that the PCB motor can output a larger torque under the same volume and current input.

[0069] Example 4 like Figure 10 As shown, the control method for the shaftless rim propeller of the present invention includes the following steps: the closed-loop feedback control of the PCB motor monitors the position or speed of the eddy current rotor in real time and dynamically adjusts the drive signal in combination with the controller to achieve high-precision motion control.

[0070] Specifically, this control method utilizes a position detection system consisting of an eddy current stator and an eddy current rotor as described in Example 1 to acquire the position or speed information of the PCB motor rotor in real time. The excitation coil in the eddy current stator generates an excitation signal. When the PCB motor rotor rotates, the sector-shaped copper plate on the eddy current rotor cuts magnetic lines of force in the magnetic field, generating an induced current. These current signals are received and decoded by the receiving coils Cos and Sin of the eddy current stator, thereby achieving accurate measurement of the PCB motor rotor's position and speed.

[0071] The controller dynamically calculates and adjusts the drive signal sent to the PCB motor stator based on the received position or speed signal, including adjusting parameters such as current magnitude, phase, and frequency. This closed-loop control method can adjust the drive parameters in real time according to the actual operating conditions, ensuring that the shaftless rim actuator operates according to the expected working conditions.

[0072] In practical applications, this control method can achieve precise control of the thruster according to different operating conditions, including start-up, acceleration, deceleration, constant speed operation, and emergency stop. Through real-time monitoring and dynamic adjustment, this method can effectively cope with external disturbances such as load changes and fluid resistance changes, maintaining stable operation of the thruster.

[0073] The implementation of this control method relies on the precise position detection capabilities of the eddy current stator and rotor described in Example 1, as well as the efficient electromagnetic drive mechanism between the PCB motor stator and the permanent magnet. The shielding layer ensures that the position detection signal is not interfered with by the motor's magnetic field, thus improving control accuracy.

[0074] Through this real-time monitoring and dynamic adjustment control method, the shaftless rim thruster can achieve more precise and efficient motion control, meeting the needs of various complex working conditions.

[0075] This closed-loop system includes an eddy current sensor, a control algorithm module (PID, FOC), and a drive circuit. The eddy current sensor feeds back the detected signal to the controller (such as an MCU), compares it with the target value, and generates a PWM signal to adjust the phase, frequency, or amplitude of the PCB motor winding current, thereby correcting the error. The above control method effectively improves the dynamic response, load disturbance resistance, and energy efficiency of the PCB motor, and is suitable for scenarios requiring precise positioning or stable speed.

[0076] Furthermore, the high-frequency response (sampling rate up to 100kHz) of the eddy current sensor can provide real-time feedback on the operating status of the PCB motor, and, in conjunction with control algorithms (which can utilize existing technologies), achieve dynamic adjustment of the thruster's speed and torque. For example, in the propulsion system of a micro-UAV, the motor power can be automatically optimized based on the water flow load, improving energy efficiency by 15% to 20% while avoiding overload damage.

[0077] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A shaftless rim-driven propeller, comprising a propeller body, characterized in that, And an eddy current stator (1), an eddy current rotor (2) and a PCB motor stator (6) arranged opposite to the propeller body; The propulsion body includes a PCB motor rotor (4), the PCB motor rotor (4) has a cylindrical shell (41), an outer edge ring (42) is provided on the outer circumferential surface of the cylindrical shell (41), the inner side of the cylindrical shell (41) has an accommodating space (43), and a plurality of shaftless propeller blades (44) are provided inside the accommodating space (43), the shaftless propeller blades (44) facing the inlet of the cylindrical shell (41); A plurality of grooves (45) are provided along the radial edge of the outer ring (42) on the side facing the inlet direction, and permanent magnets (5) are built into the grooves (45). The PCB motor stator (6) is sleeved on the cylindrical housing (41), and the PCB motor stator (6) is arranged opposite to the permanent magnet (5); The eddy current stator (1) and eddy current rotor (2) are sequentially sleeved on the cylindrical shell (41), and the eddy current rotor (2) is in contact with the other side of the outer ring (42).

2. The shaftless rim propeller according to claim 1, characterized in that, The outer ring (42) is integrally formed with the cylindrical shell (41). The outer ring (42) is disposed off-center on the outer circumferential surface of the cylindrical shell (41) and offset towards the outlet direction. The vertical line (46) of the shaftless propeller blade (44) and the outer ring (42) are located in the same vertical plane.

3. The shaftless rim propeller according to claim 2, characterized in that, The coil of the PCB motor stator (6) is arranged correspondingly to the permanent magnet (5), so that the coil can generate a magnetic field that repels the magnetic field of the permanent magnet (5).

4. The shaftless rim propeller according to claim 3, characterized in that, The permanent magnet (5) is embedded in the cylindrical shell (41) using a Heilbeck magnetic circuit array.

5. The shaftless rim propeller according to claim 4, characterized in that, It also includes a shielding layer, which is disposed between the eddy current rotor (2) and the outer ring (42) to isolate the magnetic field generated by the high-speed rotation of the permanent magnet (5) and the PCB motor stator (6).

6. The shaftless rim propeller according to claim 5, characterized in that, The shielding layer includes a shielding ring (3), which is made of tin-plated copper, copper, or aluminum foil.

7. The shaftless rim propeller according to claim 5, characterized in that, A shielding layer is formed on the other side of the outer ring (42) opposite the groove (45) by a shielding material.

8. The shaftless rim propeller according to claim 1, characterized in that, The permanent magnet (5) is protected by a hull alloy sealing sleeve.

9. The shaftless rim propeller according to claim 1, characterized in that, The eddy current stator (1) includes a signal generating section and a signal decoding section. The signal generating section includes an excitation coil, a receiving coil Cos, and a receiving coil Sin. The excitation coil is distributed on the outer ring of the PCB board, and the receiving coil Sin and Cos are alternately distributed on the top and bottom layers of the PCB board.

10. The shaftless rim propeller according to claim 9, characterized in that, The eddy current rotor (2) adopts a PCB structure, with several sector-shaped metal plates set on an annular PCB board (22).

11. The shaftless rim propeller according to claim 10, characterized in that, The fan-shaped metal plate is fixed with adhesive.

12. The shaftless rim propeller according to claim 1, characterized in that, The inner and outer arc edges of the fan-shaped metal plate are both located inside the edge of the annular PCB board (22).

13. The shaftless rim propeller according to claim 12, characterized in that, Several of the grooves (45) are square and are distributed around the central axis (47) of the cylindrical shell (41) in a basically concentric circle.

14. The shaftless rim propeller according to claim 1, characterized in that, The permanent magnet (5) is a neodymium iron boron magnet, a samarium cobalt magnet, an aluminum nickel cobalt magnet, or a ferrite magnet.

15. A method for controlling the use of a shaftless rim-driven propeller as described in any one of claims 1-14, characterized in that, The method includes the steps of: monitoring the position or speed of the PCB motor rotor (4) in real time and dynamically adjusting the drive signal in conjunction with the controller to achieve motion control of the shaftless wheel flange propeller.

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