Permanent magnet propeller for underwater thruster capable of reducing cavitation noise

Abstract

The invention discloses an underwater thruster permanent magnet propeller capable of reducing cavitation noise, and relates to the technical field of propellers, the underwater thruster permanent magnet propeller comprises a mounting plate, a propeller body and a fairing; mounting holes are formed in the mounting plate, the mounting plate is fixedly mounted on the underwater propeller through matching of bolts and the mounting holes, a main shaft is rotationally connected to the middle of one end face of the mounting plate, the fairing is fixedly connected to one end face of the mounting plate, and the propeller body is fixedly mounted at the end, away from the mounting plate, of the main shaft. The vibration reeds are installed on the inner wall of the flow guide cover, the vibration reeds can vibrate at a high speed through vortexes generated by the cavitation bubbles, and therefore the cavitation bubbles large in size are scattered into a larger number of small cavitation bubbles, the noise decibel generated by the larger number of small cavitation bubbles is lower than the noise decibel generated by the large cavitation bubbles when the larger number of small cavitation bubbles are broken, and the frequency is higher than the noise decibel generated by the large cavitation bubbles when the larger number of small cavitation bubbles are broken. Due to the fact that the wavelength of the high-frequency noise is short, the high-frequency noise is easy to absorb and scatter, one part of the high-frequency noise is directly absorbed by the flow guide cover, and the underwater environment can restrain propagation of the high-frequency noise.

Description

Technical Field

[0001] The invention relates to the technical field of propellers, and in particular to a permanent magnet propeller for an underwater propeller that reduces cavitation noise. Background Art

[0002] Permanent magnet propeller is a propeller design that uses the principle of permanent magnets. It is mainly used in propulsion systems. Compared with traditional propellers, the motor output shaft of the permanent magnet propeller is connected to the inner rotor of the permanent magnet coupler, and the outer rotor of the permanent magnet coupler is connected to the propeller hub, driving the propeller to rotate and generate thrust; the permanent magnet propeller uses the coupling of internal and external magnets to form a zero-leakage magnetic coupling sealing structure, thereby preventing water leakage in the underwater propeller.

[0003] However, when the propeller of an underwater propeller is working, the pressure on the back of the blade decreases to form a suction surface. When the pressure at a certain point drops below the critical value, the water vaporizes explosively, and the water vapor enters the gas core through the interface to expand it, forming cavitation. Fig.13 As shown, the vortex cavitation is the blade tip vortex ( Fig.13 f) and the hub vortex ( Fig.13 The low pressure in the vortex core of g) shown in Figure 1 results in that, although the vortex cavitation has fewer opportunities to contact the propeller and has little effect on the performance, it may interact with the hull slightly in front of the blade to produce a unique small erosion area. In addition, the tip vortex cavitation will significantly increase the propeller noise.

[0004] In the prior art, a Chinese patent for a propeller (publication number CN107284633B) that can reduce cavitation noise is proposed to solve the above-mentioned technical problems. The technical solution disclosed in the patent document is as follows: "A double-layer propeller structure is adopted, and a charging propeller is arranged behind the power propeller. The water flow pushed by the power propeller is blocked at the charging propeller, thereby increasing the pressure between the charging propeller and the power propeller and reducing the generation of cavitation. In addition, the water flow pushed by the power propeller drives the charging propeller to rotate, so that the charging propeller rotates, charges the ship, replenishes the ship's energy, and reduces the ship's energy consumption."

[0005] However, the above design can only reduce the cavitation at the propeller hub, but has no means to suppress the cavitation at the blade tip. On the other hand, affected by the installation space and waterproof requirements, the power generation structure must be set inside the ship. The double-layer propeller structure used in this design has greater requirements on waterproof performance. That is, since the central axis of the charging propeller is inside the main shaft of the power propeller, its principle diagram is as follows: Fig.12As shown in the figure, a is the stern shaft, b is the charging shaft, c is the power blade, d is the charging blade, and e is the ship body. During the operation, the two shafts (referring to the stern shaft a and the charging shaft b) need to rotate independently, and in order to avoid the generator shaft from directly intervening in power generation to reduce energy loss, the two shafts should not contact, so there must be a gap between the two shafts, and the end of the stern shaft a away from the power blade c is connected to the drive motor, and the end of the charging shaft b away from the charging blade d is connected to the generator. Therefore, a more complex anti-leakage structure is also required in the scheme, and based on the independent rotation of the two shafts, the anti-leakage structure is difficult to implement, and there is still leakage after long-term use and wear; in addition, in this scheme, only the hub vortex cavitation can be suppressed, and the blade tip vortex cavitation itself will also generate relatively large noise, so the effect of reducing the cavitation noise is limited. Summary of the invention

[0006] The purpose of the present invention is to provide a permanent magnet propeller for an underwater thruster that reduces cavitation noise, which can simultaneously reduce tip cavitation noise and hub cavitation noise, and solve the problem that the above-mentioned solution is difficult to take into account vortex elimination, energy recovery and waterproofing at the same time.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: A permanent magnet propeller for an underwater thruster for reducing cavitation noise comprises a mounting plate, a propeller body and a fairing; a mounting hole is provided on the mounting plate, the mounting plate is fixedly mounted on the underwater thruster by bolts in cooperation with the mounting hole, a main shaft is rotatably connected to the middle of one end face of the mounting plate, the fairing is fixedly connected to one end face of the mounting plate, and the propeller body is fixedly mounted on one end of the main shaft away from the mounting plate; a plurality of vibration reeds are fixedly mounted on the inner wall of the fairing, and the vibration reeds are arranged in a ring-like shape and equidistantly on the inner wall of the fairing.

[0008] By adopting the above technical solution, by installing a vibrating reed on the inner wall of the fairing, the vortex generated by the cavitation can be used to make the vibrating reed vibrate at high speed, thereby breaking up the larger cavitation into a larger number of small cavitations. When the larger number of small cavitations burst, the noise generated by the larger number of small cavitations is lower in decibels but higher in frequency than that of the large cavitations. Since the wavelength of high-frequency noise is short, it is easily absorbed and scattered, and a part of it is directly absorbed by the fairing, and the underwater environment will also suppress the propagation of high-frequency noise.

[0009] A further improvement of the technical solution of the present invention is that: a sealing cylinder is fixedly connected to a side of the mounting plate away from the fairing, an external magnetic cylinder is rotatably connected to a side of the sealing cylinder away from the mounting plate, and the external magnetic cylinder is coupled to a motor shaft inside the underwater propeller; a plurality of external magnets are fixedly connected to the inner wall of the external magnetic cylinder in a circular array at equal intervals, one end of the main shaft away from the propeller body extends into the interior of the sealing cylinder and is rotatably connected to the inner wall of the sealing cylinder, a plurality of internal magnets are fixedly connected to a portion of the main shaft located in the sealing cylinder, and the number of the internal magnets is equal to and corresponds one to one to the external magnets; a vortex reduction fin is installed at the hub position of the propeller body, and the vortex reduction fin is used to reduce the vortex at the hub position; a pumping component is arranged inside the fairing, and the pumping component is used to spray a cold flow to the blade tip of the propeller body, and the vortex at the hub position drives the vortex reduction fin to rotate and provides power to the pumping component.

[0010] By adopting the above technical scheme, a through groove is opened on the underwater thruster for the mounting plate to extend into the structure on one side close to the sealing cylinder. The mounting plate is fixed on the underwater thruster by bolts and the mounting holes, and the connecting parts are sealed by sealing strips. Since the connecting parts of the two are in a fixed state, the wear during use is smaller than that of the rotating shaft connection, thereby reducing water leakage; the output end of the driving motor and the main shaft are driven by magnetic coupling between the inner magnet and the outer magnet. In the magnetic coupling structure, the inner magnet and the outer magnet are separated by the sealing cylinder, so that water leakage will not occur.

[0011] A further improvement of the technical solution of the present invention is that a diffusion ring is connected to the tail of the air deflector, a guide groove is provided on the diffusion ring, the end face of the guide groove is arc-shaped, one end of the guide groove is located inside the air deflector and the tangent direction is parallel to the axial direction of the air deflector, and the angle between the two ends of the guide groove is 135°.

[0012] By adopting the above technical scheme, the tip vortex cavitation is close to the inner wall of the guide cover, and after being broken up, it is discharged and diffused to the surroundings along the guide groove, thereby diffusing the small cavitations and avoiding the accumulation of cavitations of too large size in the middle position to generate turbulence. The generation of turbulence will increase the cavitation noise. Therefore, the above means can effectively suppress the aggregation of small cavitations to generate turbulence, thereby suppressing the generation of cavitation noise.

[0013] A further improvement of the technical solution of the present invention is that: a plurality of connecting seats are fixedly connected to the outer wall of the hub of the propeller body, a movable groove is provided on the side of the connecting seat away from the hub, a movable block is slidably connected between the two sides of the inner wall of the connecting seat, a connecting column is fixedly connected to one side of the movable block, an end of the connecting column away from the movable block extends to the outside of the movable groove and is fixedly connected to a slide, a slide is provided inside the slide, a pad is slidably connected between the inner walls of the slide, a spring is fixedly connected between the pad and one side of the inner wall of the slide, a push rod is slidably connected to the side of the slide away from the hub, one end of the push rod extends to the inside of the slide and is fixedly connected to the pad, and the end of the push rod away from the pad is detachably connected to a friction block, and a friction ring used in conjunction with the friction block is detachably connected to the inside of the fairing, the friction ring and the friction block are in contact with each other and the contacting side is set to a rough surface.

[0014] By adopting the above technical solution, through the structure of the hub linkage set on the propeller body, it is possible to actively generate vibration during the rotation of the propeller body. Specifically, during the rotation of the propeller body, the friction block moves toward the side close to the friction ring under the action of centrifugal force and contacts the friction ring. At the same time, the friction block rotates along with the propeller body hub. The contact surface between the friction block and the friction ring is rough, and high-frequency vibration is exhibited during the above-mentioned relative sliding, and the push rod is vibrated, thereby assisting in breaking up the vortex cavitation bubbles.

[0015] A further improvement of the technical solution of the present invention is that a water spray hole is opened inside the propeller body blade, one end of the water spray hole is located at the blade tip end, the interior of the propeller body hub is a hollow structure, and the water spray hole is communicated with the interior of the hub; a water outlet communicated with the interior is opened at the end of the hub, and the interior of the hub is connected to the pumping component.

[0016] By adopting the above technical solution, water is sprayed toward the hub and blade tip of the propeller body through the pumping component, so that the pressure near the above two parts is increased, and the cavitation is filled with the sprayed water, thereby reducing the size of the cavitation; on the other hand, the generation and collapse of cavitation will instantly generate heat, and temperature is also a factor that directly affects the generation of cavitation. Therefore, the temperature change caused by the generation and collapse of cavitation will also affect the generation of subsequent cavitation, and the sprayed water can act as a cold flow to cool the cavitation position, thereby inhibiting the subsequent cavitation generation.

[0017] A further improvement of the technical solution of the present invention is that the pumping component includes a piston chamber opened inside the sealing cylinder, a piston plate is slidably connected between the inner walls of the piston chamber, a key shaft is fixedly connected to one side of the piston plate, a key slot is opened on one side of the inner wall of the piston chamber, the key shaft is slidably connected to the key slot, the key shaft is a hollow structure and a transmission buckle is fixedly connected to the inside, the main shaft is a hollow structure, a cavity communicating with the inside of the main shaft is arranged at the middle position of the propeller body hub, the inner wall of the sealing cylinder is located inside the main shaft and is rotatably connected with a transmission shaft, the vortex reduction fin is rotatably connected to the hub of the propeller body, the transmission shaft passes through the cavities on the main shaft and the propeller body and is fixedly connected to the central axis of the vortex reduction fin, and the transmission shaft is away from One end of the vortex reduction fin extends to the interior of the key shaft, and a transmission groove is provided at a portion of the side wall of the transmission shaft located inside the key shaft. The transmission buckle is slidably connected to the transmission groove, and the transmission groove is in a double helix shape; a water inlet hole communicating with the interior of the transmission shaft is provided at the middle portion of the piston plate, and a water outlet hole penetrating through the two end surfaces is provided at a portion of the piston plate near the lower end; a water pumping hole is provided at the end of the transmission shaft away from the vortex reduction fin, one end of the water pumping hole is connected to the external environment, and the other end is connected to the piston cavity; a socket is provided at a position off-center from the main shaft, and a water outlet pipe is plugged into the socket, and the water outlet pipe is used to connect the piston cavity and the hub of the propeller body, and a one-way valve is provided inside the water outlet pipe, the water outlet hole and the water inlet hole.

[0018] By adopting the above technical solution, the rotation of the vortex reduction fin drives the transmission shaft to rotate, and the transmission groove is in a reciprocating spiral shape. The key shaft can only make reciprocating motion in the axial direction and cannot twist under the limitation of the key groove. When the transmission shaft rotates, the key shaft can make reciprocating motion through the relative sliding of the transmission buckle and the transmission groove, and drive the piston plate to make piston motion in the piston cavity.

[0019] By adopting the above technical solution, the main shaft is divided into two parts, namely the driving shaft and the driven shaft, and a partition is set between the two parts to provide a pumping area. At the same time, a filter cartridge is set in this area, so that impurities in the pumping area can be filtered out to avoid clogging of the channel due to the impurities being pumped in. Since the transmission shaft is constantly rotating, the direction facing the input end of the pumping hole will also be constantly changed, so that impurities will not be continuously adsorbed on the filter cartridge. In addition, the filter cartridge is connected to the main shaft by screws, and the main shaft is constantly rotating to provide centrifugal force to automatically throw out the impurities on the filter cartridge, so there is no need to clean the filter cartridge.

[0020] A further improvement of the technical solution of the present invention is that: a plurality of guide fins are fixedly connected to the outer wall of the air deflector, the guide fins are set to heat conductive material, one side of the vibrating reed extends to the outside of the air deflector and contacts the guide fins; the air deflector is set to sound insulation material.

[0021] By adopting the above technical solution, the guide fin is arranged to contact the vibration reed so as to conduct part of the heat on the vibration reed to the outside of the air guide cover, thereby reducing the heat accumulation inside the air guide cover, thereby suppressing cavitation noise.

[0022] A further improvement of the technical solution of the present invention is that: an annular inner groove is provided on the inner side of the air deflector, a plurality of limit grooves are provided in the inner groove of the annular inner groove, the friction ring is placed inside the annular inner groove, a locking ring is connected to the inside of the annular inner groove by screws, the outer walls of the friction ring and the locking ring are fixedly connected with a plurality of limit blocks used in conjunction with the limit grooves, the locking ring is used to fix the friction ring, and the diffusion ring is fixedly connected to the side of the friction ring away from the friction ring.

[0023] By adopting the above technical solution, the friction ring can be unlocked by unlocking the screw used to fix the locking ring, thereby facilitating the replacement of the friction ring; the non-circular push rod at the end face is inserted into the groove on the friction block that is adapted to the shape of the push rod, and then the push rod is axially screwed on with a screw to complete the fixation, which makes replacement convenient.

[0024] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art: 1. The present invention provides a permanent magnet propeller for an underwater thruster that reduces cavitation noise. By installing a vibrating reed on the inner wall of a fairing, the vibrating reed can be vibrated at high speed by utilizing the vortex generated by the cavitation, thereby breaking up the larger cavitation into a larger number of small cavitations. When the larger number of small cavitations burst, the noise generated by the larger number of small cavitations is lower in decibels but higher in frequency than that generated by the large cavitations. Since the wavelength of high-frequency noise is shorter, it is easily absorbed and scattered, and a part of it is directly absorbed by the fairing. In addition, the underwater environment also affects the propagation of the high-frequency noise, thereby suppressing the cavitation noise generated by the propeller.

[0025] 2. The present invention provides a permanent magnet propeller for an underwater thruster that reduces cavitation noise. The main shaft and the external magnetic cylinder are transmitted in the form of magnetic coupling, that is, the external magnetic cylinder is connected to the driving shaft, and the main shaft can rotate along with the external magnetic cylinder through magnetic coupling. At the same time, the main shaft and the external magnetic cylinder are not in direct contact. A sealing cylinder for sealing is provided in the middle. The sealing cylinder is connected and fixed to the underwater thruster through a mounting plate, and is sealed at the connecting part by a sealing strip. Since the connecting parts of the two are in a fixed state, the wear during use is smaller than that of the rotating shaft connection, thereby reducing water leakage. The output end of the driving motor and the main shaft are transmitted through the magnetic coupling of the inner magnet and the outer magnet. In the magnetic coupling structure, the inner magnet and the outer magnet are separated by the sealing cylinder, so that water leakage will not occur.

[0026] 3. The present invention provides a permanent magnet propeller for an underwater thruster that reduces cavitation noise. Since the tip vortex cavitation is close to the inner wall of the fairing, it is broken up and guided out and diffused to the surroundings along the guide groove, thereby diffusing small cavitations and avoiding the accumulation of cavitations of excessive size in the middle to generate turbulence. The generation of turbulence will increase cavitation noise. Therefore, the above-mentioned means can effectively suppress the accumulation of small cavitations to generate turbulence, thereby suppressing the generation of cavitation noise.

[0027] 4. The present invention provides a permanent magnet propeller for an underwater thruster that reduces cavitation noise. Water is sprayed toward the hub and blade tip of the propeller body through a pumping component, so that the pressure near the above two parts is increased, and the cavitation is filled with the sprayed water, thereby reducing the size of the cavitation. On the other hand, the generation and collapse of cavitation will instantly generate heat, and temperature is also a factor that directly affects the generation of cavitation. Therefore, the generation and collapse of cavitation will cause temperature changes and will also affect the generation of subsequent cavitation. The sprayed water can act as a cold flow to cool the cavitation position, thereby inhibiting the generation of subsequent cavitation.

[0028] 5. The present invention provides a permanent magnet propeller for an underwater thruster that reduces cavitation noise. In order to cooperate with the friction ring, continuous friction with the friction block is required to generate vibration, so the wear of the two is relatively large during operation. Therefore, in the scheme, the friction ring and the friction block used to generate vibration are both set to a detachable structure. Specifically, the friction ring can be unlocked by unlocking the screw used to fix the locking ring, thereby facilitating the replacement of the friction ring; the push rod with a non-circular end face is inserted into a groove on the friction block that is adapted to the shape of the push rod, and then the push rod is axially screwed on with a screw to complete the fixation, thereby facilitating replacement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described below in conjunction with the accompanying drawings.

[0030] Figure 1 It is a schematic diagram of the structure of the present invention from the first viewing angle as a whole; Figure 2 It is a schematic diagram of the structure of the second viewing angle of the whole invention; Figure 3 It is a schematic cross-sectional structure diagram of the present invention as a whole; Figure 4 It is a structural schematic diagram of the propeller body and the main shaft of the present invention; Figure 5 It is a schematic cross-sectional structural diagram of a propeller body of the present invention; Figure 6 It is a schematic diagram of the split structure of the main shaft of the present invention; Figure 7 It is a schematic diagram of the split structure of the outer magnetic cylinder and the sealing cylinder of the present invention; Figure 8 It is a schematic diagram of the split structure of the air guide cover and the friction ring of the present invention; Fig. 9 For the present invention Figure 2 Enlarged view of point A in the middle; Fig.10 For the present invention Figure 2 Enlarged view of point B in the middle; Fig.11 For the present invention Figure 3 Enlarged view of point C in the middle; Fig.12It is a schematic diagram of the principle of the comparative document (Chinese patent with publication number CN107284633B); Fig.13 This is a schematic diagram of the vortex cavitation generated during the operation of the underwater propeller; Fig.14 It is a schematic diagram of the split structure of the connecting seat and the slide.

[0031] In the figure: 1, mounting plate; 11, vibrating reed; 12, guide fin; 2, main shaft; 21, driving shaft; 22, driven shaft; 23, jack; 24, hexagonal groove; 25, spacer; 26, filter cartridge; 31, sealing cylinder; 32, external magnetic cylinder; 33, external magnet; 34, internal magnet; 4, propeller body; 51, transmission shaft; 52, transmission groove; 53, keyway; 54, key shaft; 55, transmission buckle; 56, connecting hole; 57, vortex reduction fin; 61, piston chamber; 62, piston plate; 63, water inlet hole; 64, piston plate; 65, water inlet hole; 66, piston chamber; 67, piston plate; 68, water inlet hole; 69, piston chamber; 70, piston plate; 71, piston chamber; 72, piston plate; 73, water inlet hole; 74, piston plate; 75, piston chamber; 76, piston chamber; 77, piston plate; 78, piston chamber; 79, piston chamber; 80, piston chamber; 81, piston chamber; 82, piston chamber; 83, piston chamber; 84, piston chamber; 85, piston chamber; 86, piston chamber; 87, piston chamber; 88, piston chamber; 89, piston chamber; 90, piston chamber; 91, piston chamber; 92, piston chamber; 93, piston chamber; 94, piston chamber; 95, piston chamber; 96, piston chamber; 97, piston chamber; 98, piston chamber; 99, piston chamber; 100, piston chamber; 101, piston chamber; 102, piston chamber; 103, piston chamber; 104, piston chamber; 105, piston chamber; 106, piston chamber; 107, 4. Water outlet hole; 65. Pumping hole; 66. Water outlet pipe; 67. Water outlet; 68. Water spray hole; 69. Distribution chamber; 610. Hexagonal block; 71. Guide cover; 72. Annular inner groove; 73. Limit groove; 75. Limit block; 76. Diffuser ring; 77. Locking ring; 78. Guide groove; 81. Slide; 82. Slide; 83. Pad; 84. Spring; 85. Push rod; 86. Friction block; 87. Friction ring; 88. Connecting seat; 89. Movable groove; 810. Movable block; 811. Connecting column. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with embodiments: Example 1 like Figure 1 , Figure 2 and Figure 3 As shown, the present invention provides a permanent magnet propeller for an underwater thruster for reducing cavitation noise, comprising a mounting plate 1, a propeller body 4 and a fairing 71; a mounting hole is opened on the mounting plate 1, and the mounting plate 1 is fixedly mounted on the underwater thruster by bolts in cooperation with the mounting hole, a main shaft 2 is rotatably connected to the middle position of one end face of the mounting plate 1, the fairing 71 is fixedly connected to one end face of the mounting plate 1, and the propeller body 4 is fixedly mounted on one end of the main shaft 2 away from the mounting plate 1; a plurality of vibration reeds 11 are fixedly mounted on the inner wall of the fairing 71, and the vibration reeds 11 are arranged in a ring-shaped and equidistant manner on the inner wall of the fairing 71.

[0033] In this embodiment, by installing a vibrating reed 11 on the inner wall of the fairing 71, the vortex generated by the cavitation can be used to make the vibrating reed 11 vibrate at high speed, thereby breaking up the larger cavitation into a larger number of small cavitations. When the larger number of small cavitations burst, the noise generated by the larger number of small cavitations is lower in decibels but higher in frequency than that of the large cavitations. Since the wavelength of high-frequency noise is short, it is easily absorbed and scattered, and a part of it is directly absorbed by the fairing 71, and the underwater environment also suppresses the propagation of high-frequency noise.

[0034] like Figure 3 , Figure 4 and Figure 7 As shown, preferably, a sealing cylinder 31 is fixedly connected to the side of the mounting plate 1 away from the fairing 71, and an external magnetic cylinder 32 is rotatably connected to the side of the sealing cylinder 31 away from the mounting plate 1, and the external magnetic cylinder 32 is coupled to the motor shaft inside the underwater propeller; the inner wall of the external magnetic cylinder 32 is fixedly connected to a plurality of external magnets 33 in a circular array at equal intervals, and one end of the main shaft 2 away from the propeller body 4 extends into the interior of the sealing cylinder 31 and is rotatably connected to the inner wall of the sealing cylinder 31, and a plurality of internal magnets 34 are fixedly connected to the portion of the main shaft 2 located in the sealing cylinder 31, and the number of the internal magnets 34 and the external magnets 33 are equal and correspond one to one; a vortex reduction fin 57 is installed at the hub position of the propeller body 4, and the vortex reduction fin 57 is used to reduce the vortex at the hub position, and a pumping component is arranged inside the fairing 71, and the pumping component is used to spray a cold flow to the blade tip of the propeller body 4, and the vortex at the hub position drives the vortex reduction fin 57 to rotate and provides power to the pumping component.

[0035] In this embodiment, a through groove is provided on the underwater thruster for the structure of the mounting plate 1 to extend into one side close to the sealing cylinder 31. The mounting plate 1 is fixedly mounted on the underwater thruster by bolts and the mounting holes, and the connecting parts are sealed by sealing strips. Since the connecting parts of the two are in a fixed state, the wear during use is smaller than that of the rotating shaft connection, thereby reducing water leakage. The output end of the driving motor and the main shaft 2 are driven by magnetic coupling between the inner magnet 34 and the outer magnet 33. In the magnetic coupling structure, the inner magnet 34 and the outer magnet 33 are separated by the sealing cylinder 31, so that water leakage will not occur.

[0036] like Figure 2 , Fig.10 and Fig.14As shown, preferably, the outer wall of the hub of the propeller body 4 is fixedly connected with a plurality of connecting seats 88, a movable groove 89 is provided on the side of the connecting seat 88 away from the hub, a movable block 810 is slidably connected between the two sides of the inner wall of the connecting seat 88, a connecting column 811 is fixedly connected to one side of the movable block 810, an end of the connecting column 811 away from the movable block 810 extends to the outside of the movable groove 89 and is fixedly connected with a slide 81, a slide groove 82 is provided inside the slide 81, and the inner walls of the slide groove 82 are slidably connected to each other. There is a pad 83, and a spring 84 is fixedly connected between the pad 83 and one side of the inner wall of the slide groove 82. A push rod 85 is slidably connected to the side of the slide 81 away from the hub. One end of the push rod 85 extends to the inside of the slide groove 82 and is fixedly connected to the pad 83. The end of the push rod 85 away from the pad 83 is detachably connected to a friction block 86. The inside of the air deflector 71 is detachably connected to a friction ring 87 used in conjunction with the friction block 86. The friction ring 87 and the friction block 86 are in contact with each other, and the contacting side is set to a rough surface.

[0037] Relying only on the disturbance generated by the cavitation itself to make the vibrating reed 11 vibrate to disperse the cavitation has limited effect and has a certain hysteresis. The cavitation can only be dispersed after the cavitation is formed and is sufficient to disturb the vibrating reed 11. In this embodiment, by means of the hub linkage structure provided on the propeller body 4, the propeller body 4 can actively generate vibration during its rotation. Specifically, when the spring 84 is slightly compressed at the beginning, the friction block 86 is slightly in contact with the friction ring 87 under the elastic force of the spring 84, but the squeezing force is small. During the rotation of the propeller body 4, the friction block 86 further squeezes the friction ring 87 under the action of the centrifugal force. At the same time, the friction block 86 rotates along with the hub of the propeller body 4. The contact surface between the friction block 86 and the friction ring 87 is rough, and high-frequency vibration is exhibited during the above-mentioned relative sliding, and the push rod 85 is shaken, thereby assisting in breaking up the vortex cavitation. However, since the above scheme utilizes vibration to break up cavitation bubbles, and there is a problem of transmitting the vibration source to the main shaft 2, the above scheme flexibly connects the structure for generating vibration by friction with the connecting seat 88 for connecting with the hub of the propeller body 4, and the connecting part between the two is a sliding connection between a movable block 810 and a movable groove 89. The volume of the movable groove 89 is larger than that of the movable block 810, and the two sides of the inner wall thereof are slidingly connected to the movable block 810. The difference in volume between the two is only reflected in the direction of two sides thereof and the movable space is limited. The movable space in the axial direction of the push rod 85 can meet the spatial jitter requirement and will not act on the connecting seat 88 (and the hub connected thereto).

[0038] Example 2 like Figure 3 , Figure 8 and Fig.11As shown, based on Example 1, the present invention provides a technical solution: preferably, a diffusion ring 76 is connected to the tail of the air guide cover 71, and a guide groove 78 is provided on the diffusion ring 76. The end face of the guide groove 78 is arc-shaped, and one end of the guide groove 78 is located inside the air guide cover 71 and the tangent direction is parallel to the axial direction of the air guide cover 71, and the angle between the two ends of the guide groove 78 is 135°.

[0039] In the above technical solution, the cavitation bubbles are first broken up into a larger number of small cavitation bubbles by vibration. The above operation itself will cause a large disturbance to the water. At the same time, the disturbance factors such as the operation of the propeller body 4 and the rotation of the vortex reduction fins 57 are superimposed, making it easy to generate turbulence in the central part of the deflector 71, thereby generating greater noise; In this embodiment, since the tip vortex cavitation is close to the inner wall of the guide cover 71, the cavitation is broken up and discharged to the surroundings and diffused along the guide groove 78, thereby diffusing the small cavitations and avoiding the accumulation of cavitations of excessive size in the middle position to generate turbulence. The generation of turbulence will increase the cavitation noise. Therefore, the above-mentioned means can effectively suppress the accumulation of small cavitations to generate turbulence, thereby suppressing the generation of cavitation noise.

[0040] Example 3 like Figure 2 , Figure 5 and Fig. 9 As shown, on the basis of Example 2, the present invention provides a technical solution: preferably, a water spray hole 68 is opened inside the blade of the propeller body 4, one end of the water spray hole 68 is located at the tip end of the blade, the interior of the hub of the propeller body 4 is a hollow structure, and the water spray hole 68 is communicated with the interior of the hub; a water outlet 67 communicated with the interior is opened at the end position of the hub, and the interior of the hub is connected to the pumping component.

[0041] In this embodiment, water is sprayed toward the hub and blade tip of the propeller body 4 through a pumping component, so that the pressure near the above two parts is increased, and the cavitation is filled with the sprayed water, thereby reducing the size of the cavitation; on the other hand, the generation and collapse of cavitation will instantly generate heat, and temperature is also a factor that directly affects the generation of cavitation. Therefore, the generation and collapse of cavitation will cause temperature changes and will also affect the generation of subsequent cavitation, and the sprayed water can act as a cold flow to cool the cavitation position, thereby inhibiting the subsequent cavitation generation.

[0042] Example 4 like Figure 5 , Figure 6 and Figure 7As shown, on the basis of Example 3, the present invention provides a technical solution: preferably, the pumping component includes a piston chamber 61 opened in the sealing cylinder 31, a piston plate 62 is slidably connected between the inner walls of the piston chamber 61, a key shaft 54 ​​is fixedly connected to one side of the piston plate 62, a key groove 53 is opened on one side of the inner wall of the piston chamber 61, the key shaft 54 ​​is slidably connected to the key groove 53, the key shaft 54 ​​is a hollow structure and a transmission buckle 55 is fixedly connected to the inside, the main shaft 2 is a hollow structure, a cavity communicating with the inside of the main shaft 2 is provided at the middle position of the hub of the propeller body 4, the inner wall of the sealing cylinder 31 is located inside the main shaft 2 and is rotatably connected to the transmission shaft 51, the vortex reduction fin 57 is rotatably connected to the hub of the propeller body 4, the transmission shaft 51 passes through the cavities on the main shaft 2 and the propeller body 4 and is fixedly connected to the central axis of the vortex reduction fin 57, and the transmission shaft 51 is far One end away from the vortex reduction fin 57 extends to the interior of the key shaft 54, and a transmission groove 52 is provided at the position of the side wall of the transmission shaft 51 located inside the key shaft 54, and a transmission buckle 55 is slidably connected with the transmission groove 52, and the transmission groove 52 is in a double helix shape; a water inlet hole 63 communicating with the interior of the transmission shaft 51 is provided at the middle position of the piston plate 62, and a water outlet hole 64 penetrating through the two end surfaces is provided at the position near the lower end of the piston plate 62, and a water pumping hole 65 is provided at the end of the transmission shaft 51 away from the vortex reduction fin 57, one end of the water pumping hole 65 is connected to the external environment, and the other end is connected to the piston cavity 61, and a socket 23 is provided at the main shaft 2 off-center, and a water outlet pipe 66 is inserted into the interior of the socket 23, and the water outlet pipe 66 is used to connect the piston cavity 61 and the hub of the propeller body 4, and a one-way valve is provided inside the water outlet pipe 66, the water outlet hole 64 and the water inlet hole 63.

[0043] In this embodiment, the rotation of the vortex reduction fin 57 drives the transmission shaft 51 to rotate, the transmission groove 52 is in a reciprocating spiral shape, and the key shaft 54 ​​can only make axial reciprocating motion under the limitation of the key groove 53 and cannot be twisted. When the transmission shaft 51 rotates, the relative sliding of the transmission buckle 55 and the transmission groove 52 can make the key shaft 54 ​​reciprocate and drive the piston plate 62 to make piston motion in the piston cavity 61; Furthermore, when the piston plate 62 moves toward the side close to the key shaft 54, negative pressure is generated on the left side of the piston plate 62 (the side away from the key shaft 54) and positive pressure is generated on the right side of the piston plate 62 (the side close to the key shaft 54). At this time, the one-way valves in the water inlet hole 63 and the water outlet pipe 66 are both connected, while the one-way valve in the water outlet hole 64 is blocked, so that the piston chamber 61 located on the left side of the piston plate 62 draws water through the water inlet hole 63 and the water pumping hole 65, and at the same time, the piston chamber 61 located on the right side of the piston plate 62 discharges water into the hub through the water outlet pipe 66.

[0044] like Figure 3 , Figure 5 and Figure 6As shown, preferably, the main shaft 2 includes a driving shaft 21 and a driven shaft 22, and the driving shaft 21 and the driven shaft 22 are coupled and connected by flanges, and a spacer 25 is fixedly connected to the side where the two flanges are close to each other; the water pumping hole 65 is T-shaped, and a hexagonal groove 24 is provided on the side where the driving shaft 21 and the driven shaft 22 are close to each other, and a hexagonal block 610 is fixedly connected to the middle position of the water outlet pipe 66, and the hexagonal block 610 is inserted between the two hexagonal grooves 24, and a distribution chamber 69 is provided at one end of the main shaft 2 close to the sealing cylinder 31, and one end of the water outlet pipe 66 is connected to the distribution chamber 69, and the two ends of the water outlet pipe 66 are respectively located in the distribution chamber 69 and the hub of the propeller body 4; a connecting hole 56 communicating with the inside of the distribution chamber 69 is provided on one side of the inner wall of the piston chamber 61, and a filter cartridge 26 is connected between the two flanges of the main shaft 2 by screws.

[0045] Since the pumping hole 65 is arranged inside the transmission shaft 51, and the transmission shaft 51 is arranged inside the main shaft 2, a hub is installed at the end position and there are vortex cavitations, so no pumping area can be provided. Therefore, a pumping area must be arranged at the middle position of the main shaft 2; In this embodiment, the main shaft 2 is divided into two parts, namely, a driving shaft 21 and a driven shaft 22, and a partition is set between the two parts to provide a water pumping area. At the same time, a filter cartridge 26 is set in this area, so that impurities in the water pumping area can be filtered out to avoid clogging of the channel due to the impurities being pumped in. Since the transmission shaft 51 is constantly rotating, the direction facing the input end of the water pumping hole 65 will also be constantly changed, so that impurities will not continue to be adsorbed on the filter cartridge 26. In addition, the filter cartridge 26 is connected to the main shaft 2 by screws, and the main shaft 2 is constantly rotating to provide centrifugal force to automatically throw out the impurities on the filter cartridge 26, so there is no need to clean the filter cartridge 26.

[0046] like Figure 3 and Fig.11 As shown, preferably, the outer wall of the air guide cover 71 is fixedly connected with a plurality of guide fins 12, the guide fins 12 are set to heat conductive material, one side of the vibration reed 11 extends to the outside of the air guide cover 71 and contacts with the guide fins 12; the air guide cover 71 is set to sound insulation material.

[0047] In order to cope with the high-frequency vibration of the vibrating reed 11 during the disturbance process and the heat generated during the cavitation collapse process, in this embodiment, a guide fin 12 is provided to contact the vibrating reed 11 so as to conduct part of the heat on the vibrating reed 11 to the outside of the guide cover 71, thereby reducing the heat accumulation inside the guide cover 71, thereby suppressing the cavitation noise. At the same time, the structural design is not easy to hang foreign objects.

[0048] Example 5 like Figure 3 and Figure 8As shown, on the basis of Example 4, the present invention provides a technical solution: preferably, an annular inner groove 72 is opened on the inner side of the air deflector 71, and a plurality of limit grooves 73 are opened in the inner groove of the annular inner groove 72, and the friction ring 87 is placed inside the annular inner groove 72, and a locking ring 77 is connected to the inside of the annular inner groove 72 by screws, and the outer walls of the friction ring 87 and the locking ring 77 are fixedly connected with a plurality of limit blocks 75 used in conjunction with the limit grooves 73, and the locking ring 77 is used to fix the friction ring 87, and the diffusion ring 76 is fixedly connected to the side of the friction ring 87 away from the friction ring 87.

[0049] Since the friction ring 87 needs to continuously rub against the friction block 86 to generate vibration, the wear of the two during operation is relatively large; In this embodiment, the friction ring 87 can be unlocked by unlocking the screws used to fix the locking ring 77, thereby facilitating the replacement of the friction ring 87; the non-circular end face of the push rod 85 is inserted into the groove on the friction block 86 that is adapted to the shape of the push rod 85, and then the push rod 85 is axially screwed on with a screw to complete the fixation, which is convenient for replacement.

[0050] The working principle of the permanent magnet propeller for underwater thruster to reduce cavitation noise is described in detail below.

[0051] like Figure 1-Figure 14 As shown, the underwater thruster is provided with a through groove for the mounting plate 1 to extend into the structure on one side close to the sealing cylinder 31. The mounting plate 1 is fixedly mounted on the underwater thruster by bolts and the mounting holes. The connecting parts are sealed by sealing strips. Since the connecting parts of the two are in a fixed state, the wear during use is smaller than that of the rotating shaft connection, thereby reducing water leakage. The output end of the driving motor and the main shaft 2 are driven by magnetic coupling between the inner magnet 34 and the outer magnet 33. In the magnetic coupling structure, the inner magnet 34 and the outer magnet 33 are separated by the sealing cylinder 31, so that water leakage will not occur.

[0052] A fairing 71 is arranged outside the propeller body 4, which can turbulently flow the water around the propeller body 4, thereby reducing the generation of cavitation. At the same time, the fairing 71 itself is made of sound-insulating material, which can suppress the noise generated when the cavitation in the covered space collapses. When the propeller body 4 is working, hub vortex cavitation and blade tip vortex cavitation are generated at the tail. The above two groups of cavitations are cavitations concentrated in the cavitation area, and the noise is relatively large when they collapse. Both types of cavitations generate eddy currents, so that the vibrating reed 11 vibrates at a high speed. Further, the above two types of cavitations are both broken up into a larger number of small cavitations. When a larger number of small cavitations collapse, the noise generated is lower in decibel but higher in frequency than that of large cavitations. Since the wavelength of high-frequency noise is short and it is easily absorbed and scattered, sound-insulating material is correspondingly arranged on the fairing 71 to effectively absorb part of the cavitation noise, and the underwater environment will also suppress the propagation of high-frequency noise. In addition, when the propeller body 4 does not rotate, the friction block 86 does not contact the friction ring 87. When the propeller body 4 rotates, the friction block 86 moves to the side close to the friction ring 87 under the action of centrifugal force and contacts the friction ring 87. At the same time, the friction block 86 rotates along with the hub of the propeller body 4. The contact surface between the friction block 86 and the friction ring 87 is rough, and high-frequency vibration is presented during the above relative sliding, and the push rod 85 is vibrated, thereby assisting in breaking up the vortex cavitation. As the tip vortex cavitation is close to the inner wall of the guide cover 71, it is broken up and discharged to the surroundings and diffused along the guide groove 78, thereby diffusing the small cavitations and avoiding the accumulation of cavitations of too large size in the middle to generate turbulence. The generation of turbulence will increase the cavitation noise. Therefore, the above-mentioned means can effectively suppress the accumulation of small cavitations to generate turbulence, thereby suppressing the generation of cavitation noise.

[0053] Based on the above design, the present invention further provides a vortex reduction fin 57 at the tail of the hub of the propeller body 4. When the propeller body 4 is working, a hub vortex cavitation is generated at the tail of the hub. The cavitation is spiral and generates a vortex around it. When the water flow passes through the vortex reduction fin 57, it is affected by the resistance of the vortex reduction fin 57, so that the pressure between the propeller body 4 and the vortex reduction fin 57 increases, thereby reducing the formation of cavitation on the surface of the propeller body 4; in addition, the water flow pushes the vortex reduction fin 57 to rotate, so that the transmission shaft 51 rotates, thereby causing the key shaft 54 ​​to reciprocate through the cooperation of the transmission groove 52 and the transmission buckle 55 (the transmission groove 52 is reciprocating spiral, and the key shaft 54 ​​can only reciprocate in the axial direction under the limitation of the key groove 53 and cannot twist. When the transmission shaft 51 rotates, the key shaft 54 ​​can reciprocate through the relative sliding of the transmission buckle 55 and the transmission groove 52), and drives the piston plate 62 to perform piston motion in the piston cavity 61.

[0054] Reference Figure 3 When the piston plate 62 moves toward the side close to the key shaft 54, negative pressure is generated on the left side of the piston plate 62 (the side away from the key shaft 54) and positive pressure is generated on the right side of the piston plate 62 (the side close to the key shaft 54). At this time, the one-way valves in the water inlet hole 63 and the water outlet pipe 66 are both connected, while the one-way valve in the water outlet hole 64 is blocked, so that the piston chamber 61 located on the left side of the piston plate 62 pumps water through the water inlet hole 63 and the water pumping hole 65, and at the same time, the piston chamber 61 located on the right side of the piston plate 62 discharges water into the propeller hub through the water outlet pipe 66, and is divided into The water is discharged from the water outlet 67 to the tail of the hub and from the water spray hole 68 to the tip end of the propeller body 4, thereby increasing the pressure near the above two parts and filling the cavitation with the sprayed water, thereby reducing the size of the cavitation; on the other hand, the generation and collapse of cavitation will instantly generate heat, and temperature is also a factor that directly affects the generation of cavitation. Therefore, the generation and collapse of cavitation will cause temperature changes and will also affect the generation of subsequent cavitation, and the sprayed water can act as a cold flow to cool the cavitation position, thereby inhibiting the generation of subsequent cavitation.

[0055] When the piston plate 62 moves toward the side away from the key shaft 54, positive pressure is generated on the left side of the piston plate 62 (the side away from the key shaft 54) and negative pressure is generated on the right side of the piston plate 62 (the side close to the key shaft 54). At this time, the one-way valves in the water inlet hole 63 and the water outlet pipe 66 are blocked, while the one-way valve in the water outlet hole 64 is turned on, so that the water on the left side of the piston plate 62 in the piston chamber 61 in the previous process is pressed into the right side through the water outlet hole 64.

[0056] The above generally describes the present invention in detail, but it is obvious to a person skilled in the art that some modifications or improvements can be made to the present invention. Therefore, modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A permanent magnet propeller for an underwater propulsion device for reducing cavitation noise, comprising a mounting plate (1), a propeller body (4) and a fairing (71); characterized in that: The mounting plate (1) is provided with a mounting hole, and the mounting plate (1) is fixedly mounted on the underwater propeller by means of bolts that cooperate with the mounting hole; a main shaft (2) is rotatably connected to the middle of one end surface of the mounting plate (1); the fairing (71) is fixedly connected to one end surface of the mounting plate (1); and the propeller body (4) is fixedly mounted on an end of the main shaft (2) away from the mounting plate (1); a plurality of vibration reeds (11) are fixedly mounted on the inner wall of the fairing (71); the vibration reeds (11) are arranged in an annular shape and equidistantly on the inner wall of the fairing (71); A sealing cylinder (31) is fixedly connected to a side of the mounting plate (1) away from the fairing (71); an external magnetic cylinder (32) is rotatably connected to a side of the sealing cylinder (31) away from the mounting plate (1); the external magnetic cylinder (32) is coupled to a motor shaft inside the underwater propeller; a plurality of external magnets (33) are fixedly connected to the inner wall of the external magnetic cylinder (32) in a circular array at equal intervals; an end of the main shaft (2) away from the propeller body (4) extends into the interior of the sealing cylinder (31) and is rotatably connected to the inner wall of the sealing cylinder (31); a portion of the main shaft (2) located inside the sealing cylinder (31) is fixedly connected to a plurality of internal magnets (34); the number of the internal magnets (34) is equal to that of the external magnets (33) and corresponds one to one; A vortex reduction fin (57) is installed at the hub position of the propeller body (4), and the vortex reduction fin (57) is used to reduce the vortex at the hub position. A pumping component is arranged inside the fairing (71), and the pumping component is used to spray a cold flow toward the blade tip of the propeller body (4), so that the vortex at the hub position drives the vortex reduction fin (57) to rotate and provides power to the pumping component.

2. A permanent magnet propeller for an underwater propulsion device for reducing cavitation noise according to claim 1, characterized in that: The rear end of the air guide cover (71) is connected to a diffusion ring (76), and a guide groove (78) is provided on the diffusion ring (76). The end surface of the guide groove (78) is in the shape of an arc. One end of the guide groove (78) is located inside the air guide cover (71) and the tangent direction is parallel to the axial direction of the air guide cover (71). The angle between the two ends of the guide groove (78) is 135 degrees.

3. A permanent magnet propeller for an underwater propulsion device for reducing cavitation noise according to claim 2, characterized in that: The propeller body (4) is fixedly connected to a plurality of connection seats (88) on the outer wall of the hub, a movable groove (89) is provided on the side of the connection seat (88) away from the hub, a movable block (810) is slidably connected between the two sides of the inner wall of the connection seat (88), a connection column (811) is fixedly connected to one side of the movable block (810), an end of the connection column (811) away from the movable block (810) extends to the outside of the movable groove (89) and is fixedly connected to a slide frame (81), a slide groove (82) is provided inside the slide frame (81), and a pad (81) is slidably connected between the inner walls of the slide groove (82). 3), a spring (84) is fixedly connected between the pad (83) and one side of the inner wall of the slide groove (82), a push rod (85) is slidably connected to the side of the slide (81) away from the hub, one end of the push rod (85) extends into the interior of the slide groove (82) and is fixedly connected to the pad (83), one end of the push rod (85) away from the pad (83) is detachably connected to a friction block (86), the interior of the deflector (71) is detachably connected to a friction ring (87) used in conjunction with the friction block (86), the friction ring (87) and the friction block (86) are in contact with each other, and the contacting side is set to a rough surface.

4. A permanent magnet propeller for an underwater propulsion device for reducing cavitation noise according to claim 3, characterized in that: A water spray hole (68) is provided inside the blade of the propeller body (4), one end of the water spray hole (68) is located at the tip end of the blade, the inside of the hub of the propeller body (4) is a hollow structure, and the water spray hole (68) is communicated with the inside of the hub; a water outlet (67) is provided at the end of the hub, and the inside of the hub is communicated with a pumping component.

5. A permanent magnet propeller for an underwater propulsion device for reducing cavitation noise according to claim 4, characterized in that: The pumping component comprises a piston chamber (61) opened inside the sealing cylinder (31); a piston plate (62) is slidably connected between the inner walls of the piston chamber (61); a key shaft (54) is fixedly connected to one side of the piston plate (62); a key groove (53) is opened on one side of the inner wall of the piston chamber (61); the key shaft (54) is slidably connected to the key groove (53); the key shaft (54) is a hollow structure and a transmission buckle (55) is fixedly connected to the inner side; the main shaft (2) is a hollow structure. A cavity communicating with the interior of the main shaft (2) is provided at the middle of the hub of the propeller body (4); the inner wall of the sealing cylinder (31) is located inside the main shaft (2) and is rotatably connected to a transmission shaft (51); the vortex reduction fin (57) is rotatably connected to the hub of the propeller body (4); the transmission shaft (51) passes through the cavities on the main shaft (2) and the propeller body (4) and is fixedly connected to the central axis of the vortex reduction fin (57); an end of the transmission shaft (51) away from the vortex reduction fin (57) extends to a key shaft (54), a transmission groove (52) is formed in a portion of the side wall of the transmission shaft (51) located in the key shaft (54), the transmission buckle (55) is slidably connected to the transmission groove (52), and the transmission groove (52) is in a double helical shape; a water inlet (63) is formed in the middle of the piston plate (62) and is communicated with the interior of the transmission shaft (51), and a water outlet (64) is formed near the lower end of the piston plate (62) and penetrates through both end surfaces, and the transmission shaft (51) is away from the vortex reduction fin (5 A water pumping hole (65) is provided at one end of the main shaft (2), one end of the water pumping hole (65) is connected to the external environment, and the other end is connected to the piston chamber (61). A plug hole (23) is provided at a position offset from the center of the main shaft (2), and a water outlet pipe (66) is inserted into the inside of the plug hole (23). The water outlet pipe (66) is used to connect the piston chamber (61) and the hub of the propeller body (4). The inside of the water outlet pipe (66), the water outlet hole (64) and the water inlet hole (63) are all provided with a one-way valve.

6. A permanent magnet propeller for an underwater propulsion device for reducing cavitation noise according to claim 5, characterized in that: The main shaft (2) comprises a driving shaft (21) and a driven shaft (22); the driving shaft (21) and the driven shaft (22) are coupled via a flange; the sides of the two flanges close to each other are fixedly connected with a spacer (25); the pumping hole (65) is T-shaped; the sides of the driving shaft (21) and the driven shaft (22) close to each other are provided with a hexagonal groove (24); the middle of the water outlet pipe (66) is fixedly connected with a hexagonal block (610); the hexagonal block (610) is plugged into the Between the two hexagonal grooves (24), a distribution chamber (69) is provided at one end of the main shaft (2) close to the sealing cylinder (31); one end of the water outlet pipe (66) is connected to the distribution chamber (69); two ends of the water outlet pipe (66) are respectively located in the distribution chamber (69) and inside the hub of the propeller body (4); a connecting hole (56) communicating with the inside of the distribution chamber (69) is provided on one side of the inner wall of the piston chamber (61); and a filter cartridge (26) is connected between the two flanges of the main shaft (2) by screws.

7. A permanent magnet propeller for an underwater propulsion device for reducing cavitation noise according to claim 6, characterized in that: A plurality of guide fins (12) are fixedly connected to the outer side wall of the guide cover (71); the guide fins (12) are made of heat-conducting material; one side of the vibration reed (11) extends to the outside of the guide cover (71) and contacts the guide fins (12); and the guide cover (71) is made of sound-insulating material.

8. The permanent magnet propeller for underwater propulsion for reducing cavitation noise according to claim 7, characterized in that: An annular inner groove (72) is provided on the inner side of the air deflector (71), and a plurality of limit grooves (73) are provided in the inner groove of the annular inner groove (72). The friction ring (87) is placed inside the annular inner groove (72), and a locking ring (77) is connected to the inside of the annular inner groove (72) by screws. The outer side walls of the friction ring (87) and the locking ring (77) are fixedly connected with a plurality of limit blocks (75) used in conjunction with the limit grooves (73). The locking ring (77) is used to fix the friction ring (87), and the diffusion ring (76) is fixedly connected to a side of the friction ring (87) away from the friction ring (87).

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