Podded multi-rotor underwater propeller

Abstract

Disclosed in the present invention is a podded multi-rotor underwater propeller, comprising a motor housing fixed to the bottom of a support, a motor provided therein, a main shaft driven by the motor to rotate and a propeller thereof, and characterized in that: the motor is a three-phase three-layer multi-rotor motor, and comprises three single-phase multi-rotor motor sets that are installed in the axial direction of the main shaft and are each a 360-degree closed ring structure consisting of a plurality of small motors and having rotors and stators alternately arranged therein; each stator is provided with semicircular magnetic poles on two sides of a winding slot; each permanent magnet rotor is coupled to the semicircular magnetic poles of the stators at two adjacent sides so as to form a small motor; the rotors of the three motor sets are all arranged on an one-to-one basis in the axial direction of the motor and are coaxially connected in series by means of rotor shafts, the magnetic field directions of the rotors being successively offset by 120 degrees; and the main shaft is provided with a main shaft fluted disc, which serves as a timing gear meshed with pinions on each rotor shaft so as to drive the three motor sets to continuously operate, and also serves as a thrust gear to output motor torque. The propeller has higher rotating speed and efficiency, a smaller size and lighter weight.

Description

A pod-type multi-rotor underwater propulsion device Technical Field

[0001] The invention relates to a pod-type multi-rotor underwater propeller. Background Art

[0002] Motors have been used as an existing technology for more than 100 years. However, the number of applications for motors is increasing, and higher requirements are being placed on them. Currently, the scientific research field is generally concerned with how to improve the performance of existing motors. The main research direction is to develop new motors that are small in size, light in weight, highly efficient, simple in structure, and adaptable to more different applications.

[0003] As underwater power output devices, podded underwater thrusters still rely on electric motors as their core mechanism. With the increasing adoption of new energy vessels and external propulsion systems, podded underwater thrusters are often the preferred power component for these types of vessels or propulsion systems.

[0004] At present, the main structural forms of the above-mentioned pod-type underwater propulsion system are divided into the following two types:

[0005] One is the motor-propeller coaxial structure scheme: its main structure includes a fixed bracket, a motor housing fixed to the bottom of the bracket, and a motor arranged in the motor housing. The motor and the propeller are coaxial, which has the advantages of simple structure, short axial length, and relatively easy manufacturing. However, due to the coaxial arrangement of the motor and the propeller, and the synchronization of the rotation speed and the propeller, and the propeller speed of large ships is very low. Taking a thousand-ton ship as an example, the propeller speed is below 200 revolutions per minute, and the propeller speed of a 10,000-ton ship is only a few dozen revolutions per minute. The motor power is the speed multiplied by the torque, so the propeller of this type of structural scheme can only increase the torque of the motor to meet its high power at low speed. This leads to the disadvantages of its motor being large in size, heavy in weight, large in frontal area, large in resistance, and low in efficiency. Therefore, it is difficult to design a full-rotation propeller with this structural scheme;

[0006] The second option is a coaxial planetary gear reduction structure with a motor and propeller. This structure primarily consists of a fixed bracket, a motor housing fixed to the bottom of the bracket, a motor housed within the motor housing, and a planetary reduction structure. The motor shaft is concentric with the output shaft of the planetary reducer, which in turn secures the propeller. This type of propeller offers advantages such as increased motor speed, reduced motor size and weight, and reduced headwater area, reducing drag. However, due to the concentric series arrangement of the motor shaft and the planetary gear reducer shaft, the propeller has a long axial dimension, a large turning radius, and difficult steering control. The structure is relatively complex, making it difficult to design an azimuth propeller. Summary of the Invention

[0007] The purpose of the present invention is: on the one hand, the present invention is to address the shortcomings of the existing underwater thrusters mentioned in the background technology and provide a pod-type multi-rotor underwater thruster that can achieve higher rotation speeds, higher working efficiency, and at the same time has a small size, light weight, and simple structure, especially a single rotor with a short magnetic pole magnetic circuit, small magnetic resistance, and low magnetic heat loss, which can enable the full-rotation structure solution of a higher-power underwater pod-type electric thruster to be realized and applied.

[0008] The technical solution of the present invention is: a pod-type multi-rotor underwater propulsion device, comprising a bracket, a motor housing fixed to the bottom of the bracket, a motor disposed in the motor housing, a main shaft driven to rotate by the motor, and a propeller fixed thereon; characterized in that:

[0009] The motor is a three-phase three-layer multi-rotor motor or a three-phase single-layer multi-rotor motor;

[0010] The three-phase multi-layer multi-rotor motor includes three single-phase multi-rotor motor groups installed along the axial direction of the main shaft. Each single-phase multi-rotor motor group is composed of corresponding rotors and stators installed in series in an alternating circumferential direction. Each stator is provided with a winding slot in the center for winding the stator coil. Corresponding semicircular magnetic poles are provided on both sides of the winding slot, respectively coupling two adjacent permanent magnet rotors. Each permanent magnet rotor is simultaneously coupled to the semicircular magnetic poles of the stators on both sides to form a small motor. The stator coils of the three single-phase multi-rotor motor groups are connected in a delta or star configuration.

[0011] The rotors of the three single-phase multi-rotor motor groups are arranged in a one-to-one correspondence along the axial direction of the motor, and the rotors of the three single-phase multi-rotor motor groups corresponding in the axial direction are coaxially connected in series through the same rotor shaft, and their magnetic field directions are staggered by 120 degrees in sequence;

[0012] A main shaft gear is also fixed to the main shaft, and the main shaft gear is meshed with the pinion fixed on each rotor shaft. When meshing, the magnetic field direction of the rotor in each single-phase multi-rotor motor group is consistent, so that the main shaft gear serves as a timing gear for the rotors of the three single-phase multi-rotor motor groups to limit the angular relationship corresponding to all rotor magnetic fields to drive the rotors of each single-phase multi-rotor motor group to operate continuously, and also serves as a thrust gear for the rotors of the three single-phase multi-rotor motor groups to output motor torque.

[0013] The three-phase single-layer multi-rotor motor includes three equally divided arc-shaped single-phase multi-rotor motor groups installed in a closed loop with the motor's main shaft as the center, and a main shaft gear plate fixed to the main shaft for outputting the motor torque; each arc-shaped single-phase multi-rotor motor group is composed of a rotor and a stator installed alternately in series, a winding slot is provided in the center of the stator for winding the stator coil, and corresponding semicircular magnetic poles are provided on both sides of the winding slot as the center, respectively coupling two adjacent permanent magnet rotors, and each permanent magnet rotor is simultaneously coupled to the semicircular magnetic poles of the stators on both sides to form a small motor; and the stator coils of the three arc-shaped single-phase multi-rotor motor groups are connected in a triangle or star shape;

[0014] The rotor magnetic field directions of the three arc-shaped single-phase multi-rotor motor groups are staggered by 120 degrees in sequence. The main shaft gear plate is engaged with the pinion fixed on the rotor shaft of each rotor. When engaged, the magnetic field direction of the rotor in each arc-shaped single-phase multi-rotor motor group is consistent, so that the main shaft gear plate serves as the timing gear of the rotors of the three arc-shaped single-phase multi-rotor motor groups to limit the angular relationship corresponding to all rotor magnetic fields to drive the rotors of each arc-shaped single-phase multi-rotor motor group to operate continuously, and serves as the thrust gear of the rotors of the three arc-shaped single-phase multi-rotor motor groups to output motor torque.

[0015] Furthermore, the stator coils in the winding slots of the stator in the present invention are wound using flat wire windings.

[0016] Furthermore, the number of teeth of the pinion in the present invention is divisible by 3, and the number of teeth of the main shaft gear plate is divisible by X, where X=360 degrees / y, and y is the angle between two adjacent rotors on the circumference.

[0017] Furthermore, the present invention also includes a main shaft end cover, a gear box cover and a motor end cover. The gear box cover is fixed to the front end of the motor housing, and the main shaft end cover is snap-fitted and fixed to the front end of the gear box cover. A gear disc oil chamber for sealing the main shaft gear disc is formed between the main shaft end cover and the gear box cover; the motor end cover is fixed to the rear end of the motor housing, and a water seal assembly is fixed to the rear part of the motor end cover, and a water seal sleeve is provided inside the water seal assembly, which is sleeved on the main shaft and fixed to the propeller; a front bearing sleeved on the main shaft is fixed on the inner side of the main shaft end cover, and a rear bearing sleeved on the main shaft is fixed inside the motor end cover, and a fastening nut is fixed at the end of the main shaft to lock the propeller to the water seal sleeve.

[0018] Furthermore, the motor housing in the present invention includes a supporting end wall fixed to the gear box cover, the supporting end wall is formed with an outer ring wall and an inner ring wall located on the inner side of the outer ring wall, and an annular groove for embedding the three-phase three-layer multi-rotor motor or the three-phase single-layer multi-rotor motor is formed between the inner ring wall and the outer ring wall; and a plurality of internal water channels axially penetrating the motor housing are provided in the inner ring wall for cooling the three-phase three-layer multi-rotor motor or the three-phase single-layer multi-rotor motor; the main shaft end cover is provided with a water inlet hole corresponding to each internal water channel connected thereto, and the motor end cover is provided with a water outlet hole corresponding to each internal water channel connected thereto.

[0019] Furthermore, the water outlet holes on the motor end cover in the present invention are L-shaped holes, the inlet holes are axially opposite to the corresponding inner water channel, and the outlet holes are distributed radially along the motor end cover.

[0020] In actual implementation, a number of corresponding positioning ears can be formed on the outer periphery of the main shaft end cover, the outer periphery of the gear box cover, the outer periphery of the motor housing and the outer periphery of the motor end cover, and the positioning ears are provided with positioning holes for passing screws to fix the four together.

[0021] The stator has positioning protrusions at the top and bottom, while the inner ring wall has a positioning groove on its outer surface that matches the positioning protrusions at the bottom of the stator, and the inner ring wall has a positioning groove on its inner surface that matches the positioning protrusions at the top of the stator. This simplifies the manufacturing process for the motor housing, and the stator is precisely positioned when embedded in the motor housing, providing excellent heat dissipation.

[0022] The advantages of the present invention are:

[0023] 1. The pod-type multi-rotor underwater propulsor of the present invention adopts a three-phase three-layer multi-rotor motor. One advantage of the overall design of this multi-rotor motor is that each single-phase multi-rotor motor group is a 360-degree closed loop structure composed of several small motors. The magnetic circuits of all individual small motors in the closed loop are completely closed without any magnetic field loss. The wiring between adjacent stator coils in each single-phase multi-rotor motor group is extremely short, which reduces line loss, helps save the manufacturing materials of the entire motor and simplifies the production process.

[0024] Specifically, because each stator in each single-phase multi-rotor motor serves as the magnetic pole for two adjacent rotors, the magnetic field generated by the motor acts simultaneously on both rotors when energized. This significantly shortens the magnetic field path compared to all existing motors, resulting in an extremely short magnetic circuit and minimal magnetic resistance, reducing magneto-thermal losses. Furthermore, the stator's open winding slot design allows the coils to be wound with thin copper flat wire, resulting in a higher slot fill factor than any other existing motor, reducing copper heat loss and thus improving motor efficiency. Compared to the most efficient motors of the same power rating, this motor saves over 50% in silicon steel and copper, and over 95% in silicon steel and copper compared to conventional motors. Furthermore, the stator coil winding process is simpler than any existing motor. The upper and lower sides of each stator pole contact the inner and outer walls of the motor housing, creating a large contact area that effectively improves heat dissipation and enhances the motor's heat dissipation. Other materials also save to varying degrees compared to conventional motors.

[0025] 2. The overall design of this invention significantly increases rotor speed, enabling the rated operating speed of the rotors comprising each single-phase multi-rotor motor to reach many times that of a high-power motor. All rotors are coupled to a single main shaft gear, ensuring the timing relationship between all rotor angles while simultaneously reducing speed and increasing torque, while also simplifying the overall motor structure.

[0026] 3. The overall design of the present invention is small in size and light in weight. Depending on the motor speed, power and torque requirements, the volume and weight of the present high-speed motor can be half, or even smaller and lighter, with a weight of only a few tenths of that of the conventional motor.

[0027] 4. The output speed and torque of the overall design of the present invention can be flexibly designed and configured with different small motors and spindle gear plates of different sizes according to needs, thereby achieving more flexible power and speed configuration. Compared with ordinary motors, it has a wide range of speeds and does not require a gearbox, which saves the cost of gearboxes and provides more customized options.

[0028] 5. The most complicated process in the traditional motor manufacturing process is winding, especially for high-power motors, in which winding, wire embedding, and wire tying basically require manual operations. Even if small and medium-power motors can be produced with automatic winding equipment, the equipment is extremely expensive. Taking a 10-kilowatt winding production line as an example, it costs at least 10 million yuan, which is a huge investment. Moreover, a complete set of equipment can only produce one product, has no versatility, and still requires a lot of manpower. The winding process of the three-phase three-layer multi-rotor motor solution of the present invention is extremely simple. A winding equipment can be suitable for use with motors with power of tens to hundreds of kilowatts by replacing simple tooling. It has strong versatility and is very easy to achieve fully automatic production. The investment in a fully automatic production line will not exceed one-tenth of the traditional motor equipment, and unmanned production can be achieved.

[0029] 6. This invention combines all the advantages of the motor-propeller coaxial structure and the motor-propeller coaxial planetary gear reduction structure, while addressing all their disadvantages. Compared with the two existing solutions, it has a smaller size, smaller waterfront area, lighter weight, higher efficiency, more reasonable structure, simpler production process, less raw materials, lower cost, easier installation, and better maneuverability. It is more suitable for applications with azimuth electric propellers.

[0030] 7. Compared to existing pod-type underwater propulsion systems, the most significant feature of the pod-type underwater propulsion system provided in this case is the use of multiple small motors arranged around the propeller main shaft. The small gears on the rotors of the small motors engage with the main shaft gear disc to produce a larger speed ratio, thereby significantly increasing the motor speed. Compared with the existing motor-propeller coaxial structure, the weight is reduced by 90%, and the volume and water resistance are reduced by 70%. Compared with the existing motor and propeller coaxial planetary gear reduction structure, the weight is reduced by 50%, and the volume and water resistance are reduced by 50%. At the same time, the motor efficiency is greatly improved and the manufacturing cost is reduced, which greatly solves the shortcomings of the existing solutions. It is particularly suitable for the design of pod-type underwater propulsion systems with 360° horizontal rotation and full-rotation vector propulsion devices. Therefore, the pod-type multi-rotor underwater propulsion system provided in this case has great application value in the field of new energy electric ships. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0032] FIG1 is a front view of a first embodiment of a pod-type multi-rotor underwater propulsor according to the present invention;

[0033] Figure 2 is a left side view of Figure 1;

[0034] FIG3 is a schematic diagram of the three-dimensional structure of FIG1 ;

[0035] FIG4 is a schematic diagram of the three-dimensional assembly structure of FIG1 ;

[0036] FIG5 is a main cross-sectional view of FIG1;

[0037] Figure 6 is a schematic diagram of the structure of a single-phase multi-rotor motor;

[0038] FIG7 is a schematic diagram of a separate three-dimensional structure of a stator in a small motor;

[0039] FIG8 is a schematic diagram showing the corresponding rotors of three single-phase multi-rotor motor groups connected in series via a single rotor shaft;

[0040] FIG9 is a schematic diagram of the magnetic field direction of the rotor magnet of the A-phase multi-rotor motor set on the leftmost side of FIG8 ;

[0041] FIG10 is a schematic diagram of the magnetic field direction of the rotor magnet of the B-phase multi-rotor motor group located in the middle of FIG8;

[0042] FIG11 is a schematic diagram of the magnetic field direction of the rotor magnet of the rightmost C-phase multi-rotor motor set in FIG8 ;

[0043] FIG12 is a schematic diagram of the assembly structure of three single-phase multi-rotor motor groups;

[0044] FIG13 is a cross-sectional view taken along line AA in FIG12;

[0045] FIG14 is a cross-sectional view taken along line BB in FIG12;

[0046] FIG15 is a cross-sectional view taken along the CC line in FIG12;

[0047] FIG16 is a schematic diagram of the positioning structure of a single-phase multi-rotor motor group within a motor housing;

[0048] FIG17 is a schematic diagram of the magnetic circuit of a conventional single-phase AC motor;

[0049] FIG18 is a schematic diagram of the magnetic circuit of a conventional three-phase AC motor;

[0050] FIG19 is a schematic diagram of the magnetic circuit of the small motor in this case;

[0051] FIG20 is a schematic diagram of a three-dimensional assembly structure of another embodiment of the present invention;

[0052] FIG21 is a front structural schematic diagram of the three-phase single-layer multi-rotor motor used in the embodiment of FIG20 (including three arc-shaped single-phase multi-rotor motor groups installed in a closed loop);

[0053] FIG22 is a schematic diagram of the magnetic field direction of the rotor magnet of the arc-shaped A-phase multi-rotor motor set in FIG21;

[0054] FIG23 is a schematic diagram of the magnetic field direction of the rotor magnet of the arc-shaped B-phase multi-rotor motor set in FIG21;

[0055] FIG24 is a schematic diagram of the magnetic field direction of the rotor magnet of the arc-shaped C-phase multi-rotor motor group in FIG21 .

[0056] In the figure: 1. bracket; 2. motor housing; 2a. support end wall; 2b. outer ring wall; 2c. inner ring wall; 2d. positioning groove; 3. main shaft; 4. propeller; 5. rotor; 6. stator; 6a. winding groove; 6b. semicircular magnetic pole; 6c. positioning protrusion; 7. stator coil; 8. rotor shaft; 9. main shaft gear disc; 10. pinion; 11. main shaft end cover; 11a. water inlet hole; 12. gear box cover; 13. motor end cover; 13a. water outlet hole; 14. gear disc oil chamber; 15. water seal assembly; 16. water seal sleeve; 17. front bearing; 18. rear bearing; 19. fastening nut; 20. inner water channel; A. A-phase multi-rotor motor group; B. B-phase multi-rotor motor group; C. C-phase multi-rotor motor group; H. magnetic circuit. DETAILED DESCRIPTION

[0057] Example 1: The first embodiment of a pod-type multi-rotor underwater propulsion device provided in this case is described below with reference to Figures 1 to 19:

[0058] First, as shown in Figures 1 to 3, this pod-type multi-rotor underwater propulsion device, like conventional technology, has a bracket 1, a motor housing 2 fixed to the bottom of the bracket 1, a motor arranged in the motor housing 2, a main shaft 3 driven to rotate by the motor, and a propeller 4 fixed thereon.

[0059] Further combined with Figures 4 and 5, the core improvement of this embodiment is that its motor uses a three-phase three-layer multi-rotor motor, which has three single-phase multi-rotor motor groups, namely, A-phase multi-rotor motor group A, B-phase multi-rotor motor group B and C-phase multi-rotor motor group C, which are installed axially along the main shaft 3, and a main shaft gear 9 fixed to the main shaft 1 for outputting motor torque. Three single-phase multi-rotor motor groups are accommodated in the motor housing 2, the front end of the motor housing 2 is fixed with a gear box cover 12, and the main shaft end cover 11 is fastened to the front end of the gear box cover 12, and a gear disc oil chamber 14 for sealing the main shaft gear disc 9 is formed between the main shaft end cover 11 and the gear box cover 12; the motor end cover 13 is fixed to the rear end of the motor housing 2, and a water seal assembly 15 is fixed to the rear part of the motor end cover 13, and a water seal sleeve 16 is provided inside the water seal assembly 15, which is sleeved on the main shaft 3 and fixed to the propeller 4; a front bearing 17 sleeved on the main shaft 3 is fixed on the inner side of the main shaft end cover 11, and a rear bearing 18 sleeved on the main shaft 3 is fixed inside the motor end cover 13, and a fastening nut 19 is fixed at the end of the main shaft 3 to lock the propeller 4 to the water seal sleeve 16.

[0060] Further in conjunction with Figures 6 and 7, each single-phase multi-rotor motor group is composed of corresponding rotors 5 and stators 6 installed in series alternately in the circumferential direction, wherein a winding slot 6a is provided in the center of each stator 6 for winding the stator coil 7, and corresponding semicircular magnetic poles 6b are provided on both sides of the winding slot 6a as the center, respectively coupling two adjacent permanent magnet rotors 5, and each permanent magnet rotor 5 is simultaneously coupled to the semicircular magnetic poles 6b of the stators 6 on both sides to form a small motor; the stator coils 7 of the three single-phase multi-rotor motor groups are connected in a triangle or star shape.

[0061] 8 to 11 , the rotors 5 of the A-phase multi-rotor motor group A, the B-phase multi-rotor motor group B and the C-phase multi-rotor motor group C are all arranged one-to-one along the axial direction of the motor, and the rotors 5 of the three corresponding single-phase multi-rotor motor groups in the axial direction are coaxially connected in series through the same rotor shaft 8, and their magnetic field directions are staggered by 120 degrees in sequence.

[0062] As shown in Figures 4 and 5 , the main shaft gear 9 is drivingly coupled to each rotor shaft 8. Specifically, a pinion 10 is fixed to the rotor shaft 8 and meshes with the main shaft gear 9. When meshed, the magnetic field directions of the rotors 5 in each single-phase multi-rotor motor group remain consistent. As shown in Figures 13-15 , the main shaft gear 9 serves as both a timing gear for the rotors 5 of the three single-phase multi-rotor motor groups, defining the angular relationship between the magnetic fields of all the rotors 5 to drive the rotors 5 of each single-phase multi-rotor motor group to operate continuously, and a thrust gear for the rotors 5 of the three single-phase multi-rotor motor groups to output motor torque.

[0063] In this embodiment, the number of teeth of the pinion 10 is divisible by 3, and the number of teeth of the main shaft gear plate 9 is divisible by X, where X=360 degrees / y, and y is the angle between two adjacent rotors 5 on the circumference.

[0064] In this embodiment, the stator coils 7 within the winding slots 6a of the stator 6 are wound using rectangular wire. If thin copper flat wire is used, the slot fill factor is higher than any existing motor, reducing copper heat loss and thus improving motor efficiency. Compared to the most efficient existing motors of the same power, this motor uses over 50% less silicon steel and copper, and over 95% less silicon steel and copper than conventional motors.

[0065] Further in combination with Figures 1-5, the motor housing 2 includes a supporting end wall 2a fixed to the gear box cover 12, and the supporting end wall 2a is formed with an outer ring wall 2b and an inner ring wall 2c located on the inner side of the outer ring wall 2b, and an annular groove for embedding the three-phase three-layer multi-rotor motor is formed between the inner ring wall 2c and the outer ring wall 2b; and a plurality of internal water channels 20 axially penetrating the motor housing 2 are provided in the inner ring wall 2c for cooling the three-phase three-layer multi-rotor motor; the main shaft end cover 11 is provided with a water inlet hole 11a corresponding to each internal water channel 20 connected thereto, and the motor end cover 13 is provided with a water outlet hole 13a corresponding to each internal water channel 20 connected thereto.

[0066] As shown in FIG. 5 , the water outlet hole 13 a on the motor end cover 13 in this embodiment is an L-shaped hole, the inlet of which is axially opposite to the corresponding inner water channel 20 , while the outlet is distributed radially along the motor end cover 13 .

[0067] As further shown in Figure 16, for each single-phase multi-rotor motor group, the top and bottom of each stator 6 are provided with an arc-shaped positioning protrusion 6c, and the outer wall surface of the inner ring wall 2c is provided with an arc-shaped positioning groove 2d that matches the arc-shaped positioning protrusion 6c at the bottom of the stator, and the inner wall surface of the outer ring wall 2b is provided with an arc-shaped positioning groove 2d that matches the arc-shaped positioning protrusion 6c at the top of the stator 6, thereby facilitating the accurate and stable installation and positioning of the stator 6 and the motor group in which it is located by the motor housing 2.

[0068] As shown in Figures 17 to 19, since the two sides of the stator 6 in the small motor of each single-phase multi-rotor motor group in this embodiment serve as the magnetic poles of the two adjacent rotors 5, after power is applied, the force generating the magnetic field acts on the rotors 5 on both sides simultaneously. Compared with all existing types of motors, the path of the magnetic field is greatly shortened, the magnetic circuit H is extremely short, the magnetic resistance is extremely small, and the magnetic heat loss is reduced. In comparison, the magnetic circuit H of the existing three-phase AC motor is longer, and the magnetic circuit H of the single-phase AC motor is the longest, both of which are longer than the magnetic circuit H of the small motor in this case.

[0069] Example 2:

[0070] 20 to 24 show a second specific embodiment of a pod-type multi-rotor underwater propulsion device provided by the present invention. Its overall structure is the same as that of Example 1, and it also has a bracket 1, a motor housing 2 fixed to the bottom of the bracket 1, a motor arranged in the motor housing 2, a main shaft 3 driven to rotate by the motor, and a propeller 4 fixed thereon. The difference between it and Example 1 is that the motor uses a three-phase single-layer multi-rotor motor.

[0071] This three-phase single-layer multi-rotor motor has three equally divided arc-shaped single-phase multi-rotor motor groups, namely, arc-shaped A-phase multi-rotor motor group A, arc-shaped B-phase multi-rotor motor group B and arc-shaped C-phase multi-rotor motor group C, which are installed in a closed loop with the motor's main shaft 3 as the center, and a main shaft gear 9 fixed to the main shaft 3 for outputting the motor torque. The included angle of each arc-shaped single-phase multi-rotor motor group on the circumference is 120 degrees, as shown in Figure 21.

[0072] Still referring to Figure 20, the three arc-shaped single-phase multi-rotor motor groups are all accommodated in the motor housing 2, the gear box cover 12 is fixed to the front end of the motor housing 2, and the main shaft end cover 11 is fastened to the front end of the gear box cover 12, and a gear disc oil chamber 14 for sealing the main shaft gear disc 9 is formed between the main shaft end cover 11 and the gear box cover 12; the motor end cover 13 is fixed to the rear end of the motor housing 2, and a water seal assembly 15 is fixed to the rear part of the motor end cover 13, and a water seal sleeve 16 is provided inside the water seal assembly 15, which is sleeved on the main shaft 3 and fixed to the propeller 4; a front bearing 17 sleeved on the main shaft 3 is fixed on the inner side of the main shaft end cover 11, and a rear bearing 18 sleeved on the main shaft 3 is fixed inside the motor end cover 13, and a fastening nut 19 is fixed at the end of the main shaft 3 to lock the propeller 4 to the water seal sleeve 16.

[0073] Further in conjunction with Figures 21 to 24, the arc-shaped A-phase multi-rotor motor group A, the arc-shaped B-phase multi-rotor motor group B and the arc-shaped C-phase multi-rotor motor group C are all composed of corresponding rotors 5 and stators 6 alternately installed in series in a circumferential direction, wherein each stator 6 is provided with a winding slot 6a at the center for winding the stator coil 7, and corresponding semicircular magnetic poles 6b are provided on both sides of the winding slot 6a as the center, which are respectively coupled to two adjacent permanent magnet rotors 5, and each permanent magnet rotor 5 is simultaneously coupled to the semicircular magnetic poles 6b of the stators 6 on both sides to form a small motor; the stator coils 7 of the three arc-shaped single-phase multi-rotor motor groups are connected in a triangle or star shape. For the structure of the above-mentioned small motor, please refer to Figures 6 and 7 of Example 1.

[0074] 22-23 , the magnetic field directions of the rotors 5 of the arc-shaped A-phase multi-rotor motor group A, the arc-shaped B-phase multi-rotor motor group B and the arc-shaped C-phase multi-rotor motor group C are staggered by 120 degrees respectively.

[0075] As shown in FIG20 , the main shaft gear 9 is drivingly coupled to the rotor shaft 8 of each rotor 5. Specifically, a pinion 10 is fixed to the rotor shaft 8 of each rotor 5 and meshes with the main shaft gear 9. When meshed, the magnetic field directions of the rotors 5 in each arc-shaped single-phase multi-rotor motor group remain consistent, so that the main shaft gear 9 serves as both a timing gear for the rotors 5 of the three arc-shaped single-phase multi-rotor motor groups, defining the angular relationship corresponding to the magnetic fields of all rotors 5 to drive the rotors 5 of each arc-shaped single-phase multi-rotor motor group to continuously operate, and a thrust gear for the rotors 5 of the three single-phase multi-rotor motor groups to output motor torque.

[0076] Furthermore, the number of teeth of the pinion 10 is divisible by 3, and the number of teeth of the main shaft gear plate 9 is divisible by X, where X=360 degrees / y, and y is the angle between two adjacent rotors 5 on the circumference.

[0077] Similarly, the stator coils 7 within the winding slots 6a of the stator 6 in this embodiment are wound using rectangular wire. If thin copper rectangular wire is used, the slot fill factor is higher than any existing motor, reducing copper heat loss and thus improving motor efficiency. Compared to the most efficient existing motors of the same power, this saves over 50% of silicon steel and copper, and over 95% of silicon steel and copper compared to conventional motors.

[0078] The water channel structure inside the motor housing 2 in this embodiment is the same as that in Example 1 (except that the three-phase three-layer multi-rotor motor in the motor housing 2 is replaced by a three-phase single-layer multi-rotor motor). For details, please refer to the description of Example 1 and Figure 5, and will not be described in detail in this embodiment.

[0079] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the present invention and implement it accordingly. They are not intended to limit the scope of protection of the present invention. Any modifications made within the spirit of the main technical solution of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A pod-type multi-rotor underwater propulsion device, comprising a bracket (1), a motor housing (2) fixed to the bottom of the bracket (1), a motor disposed in the motor housing (2), a main shaft (3) driven to rotate by the motor, and a propeller (4) fixed thereon; characterized in that: The motor is a three-phase three-layer multi-rotor motor or a three-phase single-layer multi-rotor motor; The three-phase multi-layer multi-rotor motor comprises three single-phase multi-rotor motor groups installed along the axial direction of a main shaft (3), each single-phase multi-rotor motor group is formed by corresponding rotors (5) and stators (6) being installed in series in an alternating circumferential direction, wherein a winding slot (6a) is provided at the center of each stator (6) for winding a stator coil (7), and corresponding semicircular magnetic poles (6b) are provided on both sides of the winding slot (6a) as the center, respectively coupling two adjacent permanent magnet rotors (5), and each permanent magnet rotor (5) is simultaneously coupled to the semicircular magnetic poles (6b) of the stators (6) on both sides to form a small motor; the stator coils (7) of the three single-phase multi-rotor motor groups are connected in a triangle or star shape; The rotors (5) of the three single-phase multi-rotor motor groups are all arranged in a one-to-one correspondence along the motor axial direction, and the rotors (3) of the three single-phase multi-rotor motor groups corresponding in the axial direction are coaxially connected in series via the same rotor shaft (8), and their magnetic field directions are staggered by 120 degrees in sequence; A main shaft gear disc (9) is also fixed on the main shaft (3), and the main shaft gear disc (9) is meshed with a pinion (10) fixed on each rotor shaft (8). When meshed, the magnetic field directions of the rotors (5) in each single-phase multi-rotor motor group are kept consistent, so that the main shaft gear disc (9) serves as a timing gear for the rotors (5) of the three single-phase multi-rotor motor groups to limit the angular relationship that the magnetic fields of all the rotors (5) need to correspond to, so as to drive the rotors (5) of each single-phase multi-rotor motor group to operate continuously, and also serves as a thrust gear for the rotors (5) of the three single-phase multi-rotor motor groups to output motor torque. The three-phase single-layer multi-rotor motor comprises three equally divided arc-shaped single-phase multi-rotor motor groups installed in a closed loop with the motor's main shaft (3) as the center, and a main shaft gear disc (9) fixed to the main shaft (3) for outputting the motor torque; each arc-shaped single-phase multi-rotor motor group is formed by alternately installing a rotor (5) and a stator (6) in series, a winding slot (6a) is provided at the center of the stator (6) for winding the stator coil (7), and corresponding semicircular magnetic poles (6b) are provided on both sides of the winding slot (6a) as the center, respectively coupling two adjacent permanent magnet rotors (5), and each permanent magnet rotor (5) is simultaneously coupled to the semicircular magnetic poles (6b) of the stators (6) on both sides to form a small motor; and the stator coils (7) of the three arc-shaped single-phase multi-rotor motor groups are connected in a triangle or star shape; The magnetic field directions of the rotors (5) of the three arc-shaped single-phase multi-rotor motor groups are staggered by 120 degrees in sequence, and the main shaft gear disc (9) is meshed with the pinion (10) fixed on the rotor shaft (8) of each rotor (5). When meshed, the magnetic field directions of the rotors (5) in each arc-shaped single-phase multi-rotor motor group are all consistent, so that the main shaft gear disc (9) serves as a timing gear of the rotors (5) of the three arc-shaped single-phase multi-rotor motor groups to limit the angular relationship that all the rotors (5) magnetic fields need to correspond to, so as to drive the rotors (5) of each arc-shaped single-phase multi-rotor motor group to operate continuously, and also serves as a thrust gear of the rotors (5) of the three arc-shaped single-phase multi-rotor motor groups to output motor torque.

2. A pod-type multi-rotor underwater propulsion system according to claim 1, characterized in that The stator coil (7) in the winding slot (6a) of the stator (6) is wound using a flat wire winding.

3. The pod-type multi-rotor underwater propulsion system according to claim 1, characterized in that The number of teeth of the pinion (10) is divisible by 3, and the number of teeth of the main shaft gear disc (9) is divisible by X, where X=360 degrees / y, and y is the angle between two adjacent rotors (5) on the circumference.

4. The pod-type multi-rotor underwater propulsion system according to claim 1, characterized in that The main shaft end cover (11), the gear box cover (12) and the motor end cover (13) are also included. The front end of the motor housing (2) is fixed with the gear box cover (12), and the main shaft end cover (11) is fastened to the front end of the gear box cover (12). A gear disc oil chamber (14) for sealing the main shaft gear disc (9) is formed between the main shaft end cover (11) and the gear box cover (12); the motor end cover (13) is fixed to the rear end of the motor housing (2), and a water seal assembly is fixed to the rear of the motor end cover (13). The water seal assembly (15) is provided with a water seal sleeve (16) which is sleeved on the main shaft (3) and fixed to the propeller (4); a front bearing (17) which is sleeved on the main shaft (3) is fixed on the inner side of the main shaft end cover (11), and a rear bearing (18) which is sleeved on the main shaft (3) is fixed in the motor end cover (13); a fastening nut (19) which locks the propeller (4) to the water seal sleeve (16) is fixed at the end of the main shaft (3).

5. The pod-type multi-rotor underwater propulsion system according to claim 4, characterized in that The motor housing (2) includes a supporting end wall (2a) fixed to the gear box cover (12), the supporting end wall (2a) is formed with an outer ring wall (2b) and an inner ring wall (2c) located on the inner side of the outer ring wall (2b), and an annular groove for embedding the three-phase three-layer multi-rotor motor or the three-phase single-layer multi-rotor motor is formed between the inner ring wall (2c) and the outer ring wall (2b); and a plurality of internal water channels (20) axially penetrating the motor housing (2) are provided in the inner ring wall (2c) for cooling the three-phase three-layer multi-rotor motor or the three-phase single-layer multi-rotor motor; the spindle end cover (11) is provided with a water inlet hole (11a) corresponding to each internal water channel (20) and connected thereto, and the motor end cover (13) is provided with a water outlet hole (13a) corresponding to each internal water channel (20) and connected thereto.

6. The pod-type multi-rotor underwater propulsion system according to claim 5, characterized in that The water outlet hole (13a) on the motor end cover (13) is an L-shaped hole, the inlet of which is axially opposite to the corresponding internal water channel (20), while the outlet is distributed radially along the motor end cover (13).

7. The pod-type multi-rotor underwater propulsion system according to claim 5, characterized in that The top and bottom of the stator (6) are provided with positioning protrusions (6c), the outer wall surface of the inner ring wall (2c) is provided with a positioning groove (2d) matching the positioning protrusion (6c) at the bottom of the stator (6), and the inner wall surface of the outer ring wall (2b) is provided with a positioning groove (2d) matching the positioning protrusion (6c) at the top of the stator (6).

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