Underwater propeller

Abstract

The underwater propeller comprises an outer cylinder, two or more propelling units are coaxially arranged in the outer cylinder in series in the water flow direction, each propelling unit comprises a cylindrical stator located on the outer ring, a cylindrical rotor is rotationally assembled in the stator through bearings arranged at the two ends, and impeller blades are arranged on the inner wall of the rotor; the outer side of each impeller blade is fixed to the inner wall of the rotor, a permanent magnet is attached to the outer wall of the rotor, coils are distributed on the inner wall of the stator and are coreless coils, and the number of turns of the coils of each propelling unit is sequentially reduced from the water inlet end to the water outlet end. The coil is a coreless coil, the coreless coil eliminates iron loss, and under the condition of the same thrust, the needed current is smaller, more electricity is saved, and the efficiency is higher.

Description

underwater propulsion Technical Field

[0001] This invention relates to an underwater propulsion device, belonging to the field of propulsion technology. Background Technology

[0002] An underwater propulsion device is a device that uses an electric motor to drive a propeller, propelling water in a specific direction. The reaction force generated by the water jet propels the propeller, providing propulsion for submersibles, diving equipment, underwater robots, etc., for forward movement, turning, or attitude adjustment. It typically consists of a waterproof motor, propeller, control circuitry, and a sealed housing. It overcomes water resistance by generating directional thrust, enabling the movement and manipulation of underwater targets. It is widely used in marine exploration, underwater operations, and underwater photography.

[0003] Existing underwater propulsion systems include both single-stage and multi-stage propulsion. However, existing single-stage underwater propulsion systems typically use iron-core motors as their driving force, resulting in an iron-core structure. Iron-core motors experience energy loss in alternating magnetic fields due to hysteresis and eddy current effects, causing the iron core to heat up. This heating caused by energy loss is called iron loss. Iron loss not only affects the propulsion system's efficiency but also indirectly limits its maximum thrust. Existing civilian handheld single-stage underwater propulsion systems, limited by cavitation, generally cannot exceed 10 kg in peak thrust. Furthermore, traditional single-stage propulsion relies on a single-stage propeller to propel water. To accelerate still water to high speeds, only a single-stage blade can pressurize and accelerate it at once. The local pressure on the back of the blade quickly falls below the saturated vapor pressure of water, triggering cavitation. Once cavitation is triggered, no matter how fast the blade spins, it will only idle, and the thrust will not increase further. This is the thrust ceiling of a single-stage propulsion system. Therefore, existing single-stage underwater propulsion systems typically suffer from high iron loss, low efficiency, and a low thrust ceiling. Existing multi-stage propulsion systems typically involve multiple independent electronic speed controllers (ESCs). Each drive motor corresponds to an ESC, and each ESC independently controls the speed and direction of its motor. This results in high costs, complex structures, poor waterproofing and reliability, and the presence of an iron core in the multi-stage structure can lead to cumulative iron losses and low propulsion efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide an underwater thruster to solve the problems of high iron loss, low efficiency, and low thrust ceiling in existing underwater thrusters.

[0005] To solve the above problems, the underwater propulsion device involved in this invention adopts the following technical solution: an underwater propulsion device includes an outer cylinder, and two or more propulsion units are coaxially connected in series inside the outer cylinder along the water flow direction. The propulsion unit includes a cylindrical stator on the outer ring, and a cylindrical rotor is rotatably assembled inside the stator through bearings at both ends. Impeller blades are provided on the inner wall of the rotor, and the outer side of each impeller blade is fixed to the inner wall of the rotor. A permanent magnet is attached to the outer wall of the rotor, and a coil is arranged on the inner wall of the stator. The coil is a coreless coil, and the number of turns of the coil in each propulsion unit decreases sequentially from the water inlet end to the water outlet end.

[0006] Each propulsion unit is connected in parallel and shares the same power supply and electronic speed controller.

[0007] The inner wall of the stator is provided with an epoxy resin potting layer that seals and encapsulates each coil, and the epoxy resin potting layer contains insulating soft magnetic powder.

[0008] The insulating soft magnetic powder accounts for 30%-50% of the weight of the epoxy resin potting layer.

[0009] The stator has a sandwich space, the coil is located in the sandwich space, and the epoxy resin potting layer is also located in the sandwich space.

[0010] The interlayer space is formed by the space between the inner stator portion and the outer stator portion arranged coaxially, and the thickness of the epoxy resin potting layer is the thickness of the interlayer space.

[0011] The outer wall of the rotor is a stepped shaft with a large diameter in the middle, the bearings are located on the small diameter portions at both ends of the rotor, and the permanent magnets are located in the middle part of the rotor.

[0012] The gap between the middle part of the rotor and the stator is uniform.

[0013] The gap between the middle part of the rotor and the stator is 0.3mm-3mm.

[0014] The axial spacing between two adjacent propulsion units is 5-15mm.

[0015] The propulsion unit of the present invention includes a cylindrical stator on the outer ring, and a cylindrical rotor rotatably mounted inside the stator via bearings at both ends. Impeller blades are provided on the inner wall of the rotor, and the outer side of each impeller blade is fixed to the inner wall of the rotor. A permanent magnet is attached to the outer wall of the rotor, and a coil is arranged on the inner wall of the stator. The coil is an ironless coil, which eliminates iron loss. Under the same thrust, it requires less current, is more energy-efficient, and has higher efficiency.

[0016] The outer cylinder of this invention has two or more propulsion units connected in series coaxially along the water flow direction. The two or more propulsion units work together to accelerate step by step, which can increase the total thrust and raise the thrust ceiling.

[0017] In this invention, the number of coil turns in each propulsion unit decreases sequentially from the inlet to the outlet, replacing multiple ESC controls with differences in the number of turns. This reduces the number of wiring points and sealing points in the entire machine, resulting in an extremely low failure rate. Furthermore, because there is no complex electronic control and heat dissipation system, the overall weight is lighter, the inertia is lower, and the ineffective power consumption during motor start-up and acceleration is significantly reduced, further achieving energy savings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below: Figure 1 is a structural schematic diagram of the embodiment of the present invention; Figure 2 is a front view of Figure 1; Figure 3 is a structural schematic diagram of section AA of Figure 2; Figure 4 is a partial enlarged view of point B in Figure 3; Figure 5 is a structural schematic diagram of the propulsion unit in Figure 1; Figure 6 is a structural schematic diagram of the stator and coil assembly in Figure 5.

[0019] The diagram is labeled as follows: 1. Outer cylinder, 2. Propulsion unit, 3. Stator, 4. Bearing, 5. Rotor, 6. Impeller blade, 7. Permanent magnet, 8. Coil, 9. Epoxy resin potting layer, 10. Inner stator section, 11. Outer stator section. Detailed Implementation

[0020] To make the technical objectives, technical solutions, and beneficial effects of the present invention clearer, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention; that is, the described embodiments are merely some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] In a specific embodiment of the underwater propulsion device involved in this invention, as shown in Figures 1-6, it has an outer cylinder 1. Two or more propulsion units 2 are coaxially connected in series within the outer cylinder 1 along the water flow direction. All propulsion units 2 work together to progressively accelerate the water flow. Each propulsion unit 2 includes a cylindrical stator 3 on the outer ring. Each propulsion unit 2 is fixed to the inner wall of the outer cylinder 1 via its stator 3. A cylindrical rotor 5 is rotatably mounted within the stator 3 via bearings 4 at both ends. The rotor 5 is hollow, and impeller blades 6 are integrally formed on the inner wall of the rotor 5. The outer side of each impeller blade 6 is fixed to the inner wall of the rotor 5. A hollow channel is formed in the rotor 5 at the gap between each impeller blade 6. A permanent magnet 7, which is neodymium iron boron, is attached to the outer wall of the rotor 5. A coil 8, which is a coreless coil, is arranged on the inner wall of the stator 3. The stator 3, bearings 4, rotor 5, impeller blades 6, permanent magnet 7, and coil 8 together constitute a shaftless motor, that is, a motor without an output shaft. When the power is turned on, the rotor 5, carrying the impeller 6, rotates in the stator 3, thus pushing the water flow from the inlet to the outlet and causing the water to spray out from the outlet. The reaction force generated by the water jet propels the propulsion unit 2 in the opposite direction of the water flow. The water flows directly through the hollow channel of the rotor 5 without any obstruction. Compared with the prior art, the water flow experiences less resistance and generates greater thrust. The number of coil turns of the coil 8 of each propulsion unit 2 decreases sequentially from the inlet to the outlet. By gradually decreasing the number of turns, the rotational speed of the rotor 5 of each propulsion unit 2 is controlled, thereby promoting the flow rate of each segment of water in stages. This allows the rotational speed of each rotor 5 to match the acceleration law of each segment of water flow step by step, preventing cavitation and increasing propulsion efficiency.

[0022] Specifically, there are three propulsion units 2, which together form a three-stage propulsion system. These three propulsion units 2 are connected in parallel and share the same power supply (not shown in the diagram) and electronic speed controller (not shown in the diagram). The connection method between the power supply and the electronic speed controller and each propulsion unit 2 is conventional. Using the same electronic speed controller ensures that the rotational speed of the rotor 5 in each stage of the propulsion system matches the water flow speed, resulting in a simple structure and low cost.

[0023] Specifically, in this embodiment, the preferred number of coil turns for the three-stage propulsion unit is a ratio of 24 turns, 18 turns, and 12 turns. In other embodiments, those skilled in the art can select the turn ratio according to actual needs, as long as the number of coil turns of the coil 8 in each propulsion unit 2 decreases sequentially from the water inlet end to the water outlet end.

[0024] Specifically, the inner wall of the stator 3 is provided with an epoxy resin potting layer 9 that seals and encapsulates each coil 8. The epoxy resin potting layer 9 contains insulating soft magnetic powder. This potting structure, formed by the epoxy resin potting layer 9, achieves high power and high efficiency within a very small volume, while also providing waterproofing to prevent water from corroding the coils 8 and the insulating soft magnetic powder. The insulating soft magnetic powder is non-conductive; it only increases the magnetic permeability of the stator 3, preventing the magnetic field from wandering and thus enhancing the motor's magnetic field and improving efficiency.

[0025] Specifically, the insulating soft magnetic powder accounts for 40% of the weight of the epoxy resin potting layer 9. This improves the permeability of stator 3, reduces leakage flux, and ensures complete non-conductivity, preventing short circuits in the three-phase windings. In other embodiments, this percentage can be selected between 30% and 50%. The insulating soft magnetic powder includes all magnetically conductive materials, such as iron sand resin, silicon steel sheets, ferrite, and soft magnetic composite materials. In this embodiment, the insulating soft magnetic powder is ferrite soft magnetic powder.

[0026] Specifically, the stator 3 has a sandwich space, the coil 8 is located in the sandwich space, and the epoxy resin potting layer 9 is also located in the sandwich space.

[0027] Specifically, the stator 3 is a one-piece molded double-layer cylinder, consisting of an inner stator section 10 and an outer stator section 11 arranged coaxially. There is an annular interlayer space between the inner stator section 10 and the outer stator section 11. The epoxy resin potting layer 9 is located within this interlayer space, and the thickness of the epoxy resin potting layer 9 is the same as the thickness of the interlayer space. The epoxy resin potting layer 9 fills the entire interlayer space, supporting both the inner stator section 10 and the outer stator section 11, and encapsulating the coil 8 within the interlayer space, completely isolating the coil 8 from water, thus achieving a waterproof function and solving the problem of potting in coreless motors.

[0028] Specifically, the outer wall of rotor 5 is a stepped shaft with a large diameter in the middle. Bearings 4 are located on the smaller diameter sections at both ends of rotor 5. The outer diameter of the thinner sections at both ends of rotor 5 is interference-fitted with the inner diameter of the inner ring of bearing 4. The inner ring of bearing 4 rotates synchronously with rotor 5. Permanent magnet 7 is located in the middle of rotor. In this way, both ends of rotor 5 are supported by bearings 4, which improves the rotational stability of rotor 5. Furthermore, the thickness of the large diameter section of rotor 5 can be adjusted according to the air gap. The outer ring of stator 3 extends upward and downward with two extension sections. Each extension section is the thickness of one bearing 4. The inner diameter of the extension section is interference-fitted with the outer diameter of the outer ring of bearing 4 to fix the outer ring of bearing 4, ensuring that the outer ring of bearing 4 is relatively stationary with respect to stator 3. The two bearings 4 ensure that rotor 5 and stator 3 are always coaxial and will not wobble during rotation. These extension sections are the two smaller diameter sections of the stepped shaft of rotor.

[0029] Specifically, the gap between the middle part of rotor 5 and stator 3 is uniform and does not fluctuate, maximizing the utilization of the motor's magnetic field. Rotor 5 is manufactured as a single piece, ensuring high coaxiality; both ends of rotor 5 are supported by double bearings, preventing wobbling during rotation; stator 3 is a single-piece double-layer cylinder with a naturally round inner wall, not pieced together, preventing warping. The coaxiality tolerance of stator 3 is ≤0.05mm, and the coaxiality tolerance of rotor 5 is ≤0.03mm. Bearing 4 is a P5-grade high-precision bearing.

[0030] Specifically, the gap between the middle part of the rotor 5 and the stator 3 is preferably 1 mm. In other embodiments, it can be selected between 0.3 mm and 3 mm.

[0031] Specifically, the axial spacing between two adjacent propulsion units 2 is preferably 10 mm. This effectively avoids water flow turbulence between different stages of the propulsion system. In other embodiments, a spacing between 5 and 15 mm can be selected.

[0032] In the above embodiments, an epoxy resin potting layer is provided on the inner wall of the stator to seal and encapsulate each coil. This is an optimized technical solution. In other embodiments, the epoxy resin potting layer can be replaced with a polyurethane layer.

[0033] In the above embodiments, the insulating soft magnetic powder is ferrite powder, which is an optimized technical solution. In other embodiments, the insulating soft magnetic powder can also be a soft magnetic composite material.

[0034] In the above embodiments, the permanent magnet includes neodymium iron boron. In other embodiments, the permanent magnet can also be an existing permanent magnet such as ferrite.

[0035] Finally, it should be noted that the above embodiments are only for illustration and not for limiting the technical solutions of the present invention. Any equivalent substitutions, modifications or partial substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An underwater propulsion device, characterized in that, The device includes an outer cylinder, inside which two or more propulsion units are coaxially connected in series along the water flow direction. Each propulsion unit includes a cylindrical stator on the outer ring, and a cylindrical rotor is rotatably mounted inside the stator via bearings at both ends. Impeller blades are provided on the inner wall of the rotor, and the outer side of each impeller blade is fixed to the inner wall of the rotor. A permanent magnet is attached to the outer wall of the rotor, and a coil is arranged on the inner wall of the stator. The coil is a coreless coil, and the number of turns of the coil in each propulsion unit decreases sequentially from the water inlet end to the water outlet end.

2. The underwater thruster according to claim 1, characterized in that, Each propulsion unit is connected in parallel and shares the same power supply and electronic speed controller.

3. The underwater thruster according to claim 2, characterized in that, The inner wall of the stator is provided with an epoxy resin potting layer that seals and encapsulates each coil, and the epoxy resin potting layer contains insulating soft magnetic powder.

4. The underwater thruster according to claim 3, characterized in that, The insulating soft magnetic powder accounts for 30%-50% of the weight of the epoxy resin potting layer.

5. The underwater propulsion device according to claim 1, 2, 3, or 4, characterized in that, The stator has a sandwich space, the coil is located in the sandwich space, and the epoxy resin potting layer is also located in the sandwich space.

6. The underwater thruster according to claim 5, characterized in that, The interlayer space is formed by the space between the inner stator portion and the outer stator portion arranged coaxially, and the thickness of the epoxy resin potting layer is the thickness of the interlayer space.

7. The underwater thruster according to claim 1, characterized in that, The outer wall of the rotor is a stepped shaft with a large diameter in the middle, the bearings are located on the small diameter portions at both ends of the rotor, and the permanent magnets are located in the middle part of the rotor.

8. The underwater thruster according to claim 7, characterized in that, The gap between the middle part of the rotor and the stator is uniform.

9. The underwater thruster according to claim 8, characterized in that, The gap between the middle part of the rotor and the stator is 0.3mm-3mm.

10. The underwater thruster according to claim 1, characterized in that, The axial spacing between two adjacent propulsion units is 5-15mm.

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