Small underwater shaftless propeller

Abstract

The utility model relates to an underwater propeller, in particular to a small underwater shaftless propeller which comprises a shell and a motor assembly, an upper cover and a lower cover are arranged at the two ends of the shell respectively, a water inlet and a water outlet are formed in the middle of the lower cover and the middle of the upper cover respectively, the motor assembly comprises a stator and a rotor, and propeller blades are arranged in the rotor. The stator is annular and is arranged in a sealing sleeve, one end of the sealing sleeve is provided with an opening, and the opening is covered and sealed by the upper cover to form a sealed cavity; the sealing sleeve is in a hollow cylinder shape, the peripheral wall is provided with an inner ring wall and an outer ring wall, one end of the outer ring wall and one end of the inner ring wall are connected to form a stator groove of a ring structure, and the stator is tightly matched in the stator groove. The sealing cavity formed by the sealing sleeve and the upper cover effectively prevents water from entering the motor, the motor assembly is protected against water erosion, and the waterproof performance of the propeller is improved. The tight fit design of the circular ring structure of the stator groove and the stator further enhances the sealing performance, and reduces the possibility of water permeation.

Description

Technical Field

[0001] This utility model belongs to the field of marine engineering technology and relates to an underwater propulsion device, especially a small underwater shaftless propulsion device. Background Technology

[0002] Currently, shaftless propellers mainly consist of blades, a motor rotor, a multi-pole stator, water-lubricated bearings, and a guide casing. Compared with traditional propeller propellers, shaftless propellers have advantages such as high efficiency, smaller space occupation in the ship's cabin, lower noise, and less vibration, and are widely used in marine scientific research, underwater resource exploration, and other fields. Therefore, shaftless propellers are required to be both airtight and waterproof inside the propeller while ensuring smooth rotor rotation.

[0003] Patent CN110450932A discloses a small underwater thruster that uses a plastic encapsulation method for waterproofing. However, for thrusters operating underwater for extended periods, this method offers poor durability and weather resistance, making it prone to sealant failure and leakage. Since plastic encapsulation is a one-time waterproofing method, repairs are difficult once it fails. Furthermore, while the sealant method ensures complete water isolation from the interior of the small underwater thruster, it can lead to dry friction of the sliding bearings during operation. Dry friction reduces bearing life, increases resistance, and lowers the overall efficiency of the thruster. Moreover, the intense heat generated during dry friction accelerates the aging of the sealant due to prolonged exposure to high temperatures, leading to seal failure and rendering the thruster unusable.

[0004] Therefore, providing an effective way to ensure waterproofing inside the thruster while guaranteeing smooth rotor rotation is a pressing technical problem that needs to be solved. Utility Model Content

[0005] The technical problem to be solved by this utility model is: in order to solve the problems of poor sealing effect and non-smooth rotor rotation in existing underwater shaftless thrusters, a small underwater shaftless thruster is provided, which uses a sealing sleeve to seal the stator to ensure waterproof effect, sets up a sliding bearing assembly and uses water for lubrication to ensure smooth rotor rotation, simplifies the structure and is easy to install.

[0006] The technical solution adopted by this utility model to solve its technical problem is: a small underwater shaftless thruster, including a shell and a motor assembly located inside the shell. An upper cover and a lower cover are respectively provided at both ends of the shell. Through holes are opened in the middle of the lower cover and the upper cover to form a water inlet and a water outlet, respectively. The motor assembly includes a stator and a rotor. The stator is located radially outside the rotor, and propeller blades are provided inside the rotor.

[0007] The stator is annular and disposed within a sealing sleeve. One end of the sealing sleeve is open and the opening is covered and sealed by the top cover to form a sealed cavity.

[0008] The sealing sleeve is a hollow cylinder with an inner ring wall and an outer ring wall on its periphery. One end of the outer ring wall and the inner ring wall are connected to form a stator groove with a circular structure, and the stator is tightly fitted in the stator groove.

[0009] The motor assembly (including the stator and rotor) is integrated with the housing and propeller blades, reducing the number of parts and connection points, and improving overall structural stability and reliability. The sealed cavity formed by the sealing sleeve and top cover effectively prevents water from entering the motor, protecting the motor assembly from water corrosion and improving the propeller's waterproof performance. The annular structure of the stator slots and the tight-fitting design of the stator further enhance the sealing performance, reducing the possibility of water infiltration.

[0010] According to one embodiment of this utility model, a wire outlet is provided at the end of the outer ring wall away from the opening. Providing a wire outlet facilitates the extraction of the stator winding leads and prevents damage to the leads or water seepage.

[0011] According to one embodiment of this utility model, the edges of the corresponding openings of the inner and outer ring walls are folded inward and outward respectively to form folded edges. The folded edges enhance the structural strength of the sealing sleeve and provide a supporting surface for the subsequent installation of the sealing ring.

[0012] According to one embodiment of this utility model, the upper cover is provided with groove I and groove II, and a protrusion is formed between groove I and groove II to tightly fit the opening of the sealing sleeve. The design of groove I and groove II makes the fit between the upper cover and the sealing sleeve tighter, further improving the sealing performance.

[0013] According to one embodiment of this utility model, a first sealing ring is provided in groove I, and the folded edge of the outer ring wall abuts against the first sealing ring; a second sealing ring is provided in groove II, and the folded edge of the inner ring wall abuts against the second sealing ring. The double sealing ring design enhances the sealing effect and prevents water from seeping in from the connection between the sealing sleeve and the top cover.

[0014] According to one embodiment of this utility model, the inner wall of the outer shell abuts tightly against the outer ring wall of the sealing sleeve, and the edge of the inner wall of the outer shell presses against the folded edge of the outer ring wall. The tight fit between the outer shell and the sealing sleeve further enhances the stability and sealing performance of the overall structure.

[0015] Both the lower cover near the inlet and the upper cover near the outlet have water perforations. A structural component is installed at each inlet and outlet, and a sliding bearing assembly is connected to the rotor. The sliding bearing assembly has an internal gap I, which communicates with the water perforations to form a water lubrication passage. Lubrication between the rotor and the sliding bearing assembly is achieved through the water lubrication passage (gap I), utilizing the fluidity of water to reduce friction and wear.

[0016] According to one embodiment of the present invention, the sliding bearing assembly includes a first sliding bearing and a second sliding bearing. The first sliding bearing has an annular structure with one end folded towards the center to form a groove. The second sliding bearing has an annular structure and is placed in the groove, with the two bearings in contact and having a gap I. The dual sliding bearing design improves the rotor's support stability, and the gap I provides flow space for water lubrication.

[0017] According to one embodiment of this utility model, annular grooves for accommodating first sliding bearings are provided at both ends of the rotor, and the first sliding bearings are tightly fitted within the annular grooves. The annular groove design makes the connection between the first sliding bearing and the rotor more stable, reducing vibration and wear.

[0018] According to one embodiment of the present invention, a boss protrudes from the outer wall of the structural member, and the inner wall of the second sliding bearing is tightly fitted onto the outer wall of one side of the boss and is limited by the boss. The boss design limits the position of the second sliding bearing, prevents its axial movement, and improves the stability of the bearing.

[0019] According to one embodiment of this utility model, the outer wall of the other side of the boss mates with the inner wall of the upper or lower cover. The mating of the boss with the upper or lower cover further enhances the integrity and stability of the structure.

[0020] According to one embodiment of this utility model, the first sliding bearing is a ceramic bearing, and the second sliding bearing is a graphite bearing. The ceramic bearing has high hardness and wear resistance, while the graphite bearing has good self-lubricating properties. Water enters between the ceramic and graphite bearings through permeable holes, preventing dry friction and improving the bearing's service life.

[0021] According to one embodiment of this utility model, a gap II is provided between the outer peripheral wall of the rotor and the inner annular wall of the sealing sleeve. This gap II communicates with the water-permeable hole to form a water cooling passage. The gap II between the rotor and the sealing sleeve forms a water cooling passage, which uses water flow to remove the heat generated by the motor assembly during operation, effectively reducing the motor temperature, improving the efficiency and stability of the motor, and enabling it to maintain good working condition under high load and long-term operation.

[0022] According to one embodiment of this utility model, the stator is a plastic-encapsulated stator. The plastic-encapsulated stator has good waterproof and insulating properties, making it suitable for underwater use.

[0023] According to one embodiment of this utility model, a plurality of propeller blades are evenly distributed inside the rotor, and the propeller blades are bonded to the rotor by adhesive bonding, tight fitting, or integral molding. The uniform distribution of the propeller blades improves propulsion efficiency, and the multiple optional connection methods provide manufacturing flexibility.

[0024] According to one embodiment of the present invention, the outer casing is provided with a cable outlet hole, and the upper cover and the lower cover are connected to the outer casing by fastening screws.

[0025] The beneficial effects of this utility model are:

[0026] (1) High sealing performance: Through the design of sealing sleeve, sealing ring and folded edge, water is effectively prevented from seeping into the motor;

[0027] (2) High-efficiency lubrication and cooling: The water lubrication and cooling channels formed by the water-permeable holes and gaps reduce mechanical wear and overheating problems;

[0028] (3) Structural stability: The design of sliding bearing assembly, boss and annular groove enhances the support and stability of the rotor, ensuring smooth rotor rotation;

[0029] (4) Ease of manufacturing and maintenance: The cable outlet and fastening screw connection facilitate manufacturing, installation and maintenance;

[0030] (5) High performance: Ceramic bearings, graphite bearings and arc surface design improve the durability and hydrodynamic performance of the thruster.

[0031] This invention relates to a small underwater shaftless thruster that features high reliability, long lifespan, and low maintenance costs, making it suitable for underwater applications. Attached Figure Description

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Figure 1 This is a perspective view of Embodiment 1 of the small underwater shaftless propulsion device of this utility model.

[0034] Figure 2 This is a cross-sectional view of Embodiment 1 of the small underwater shaftless thruster of this utility model.

[0035] Figure 3 This is an exploded view of Embodiment 1 of the small underwater shaftless thruster of this utility model.

[0036] Figure 4 This is a cross-sectional view of the assembly drawing of Embodiment 1 of the small underwater shaftless thruster of this utility model.

[0037] Figure 5 This is a schematic diagram of the upper cover structure in Embodiment 1 of the small underwater shaftless propulsion device of this utility model.

[0038] Figure 6 This is a cross-sectional view of the sealing sleeve in Embodiment 1 of the small underwater shaftless thruster of this utility model.

[0039] Figure 7This is an assembly diagram of the rotor and sliding bearing assembly in Embodiment 1 of the small underwater shaftless propulsion device of this utility model.

[0040] Figure 8 This is an assembly drawing of the structural components and the second sliding bearing in Embodiment 1 of the small underwater shaftless propulsion device of this utility model.

[0041] Figure 9 This is an assembly drawing of the rotor, sliding bearing assembly, and structural components in Embodiment 1 of the small underwater shaftless propulsion device of this utility model.

[0042] Figure 10 This is an assembly drawing of the structural components and the lower cover in Embodiment 1 of the small underwater shaftless propulsion device of this utility model.

[0043] Figure 11 This is an assembly diagram of the upper cover, the first sealing ring, and the second sealing ring in Embodiment 1 of the small underwater shaftless propulsion device of this utility model.

[0044] Figure 12 This is an assembly drawing of the outer shell, sealing sleeve, upper cover and structural components in Embodiment 1 of the small underwater shaftless thruster of this utility model.

[0045] Figure 13 This is a cross-sectional view of the upper cover in Embodiment 2 of the small underwater shaftless thruster of this utility model.

[0046] Figure 14 This is a cross-sectional view of the lower cover in Embodiment 3 of the small underwater shaftless thruster of this utility model.

[0047] In the diagram: 1. Top cover; 11. Outlet; 12. Water permeable hole; 2. Outer shell; 21. Cable outlet; 3. Bottom cover; 31. Inlet; 4. Fastening screw; 5. Stator; 6. Rotor; 61. Ring groove; 7. Propeller blade; 8. Structural component; 81. Boss; 9. Sealing sleeve; 90. Stator groove; 91. Inner ring wall; 92. Outer ring wall; 93. Cable outlet; 13. First sliding bearing; 131. Groove; 14. Second sliding bearing; 15. Groove I1; 16. Groove II; 17. First sealing ring; 18. Second sealing ring. Detailed Implementation

[0048] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention, and therefore only show the components relevant to the present invention.

[0049] Example 1

[0050] like Figure 1As shown, the small underwater shaftless thruster of this embodiment is structurally divided into an upper cover 1, an outer shell 2, and a lower cover 3, with the upper cover 1 and lower cover 3 respectively located at both ends of the outer shell 2. The upper cover 1 and lower cover 3 each have a circular through-hole in the center, forming a water outlet 11 in the middle of the upper cover 1 and a water inlet 31 in the middle of the lower cover 3, respectively. The upper cover 1 and lower cover 3 are fixed to the outer shell 2 by fastening screws 4. Multiple water-permeable holes 12 are provided on the upper cover 1 near the water outlet 11, allowing water to enter the shaftless thruster through these holes during underwater operation to lubricate the internal sliding bearings. A wiring hole 21 is provided on the outer shell 2 to allow the external wiring of the stator 5 to be routed out.

[0051] like Figures 2-4 As shown, a motor assembly is housed within the outer casing 2. The motor assembly includes a stator 5 and a rotor 6. The stator 5 is located radially outward of the rotor 6, and a propeller blade 7 is installed inside the rotor 6. A structural component 8 is located at each end of the rotor 6, on the outlet 11 and inlet 31 respectively. The function of the structural component 8 is to axially limit the rotor 6, preventing axial movement of the rotor 6 during motor assembly operation. A sliding bearing assembly is provided between the structural component 8 and the rotor 6. The sliding bearing assembly has a gap I inside, which communicates with the water permeable hole 12 to form a water lubrication passage (e.g., ...). Figure 2 (As indicated by the solid arrow).

[0052] The stator 5 is annular and housed within a sealing sleeve 9. One end of the sealing sleeve 9 is open, and this opening is covered and sealed by the upper cover 1 to form a sealed cavity. A gap II exists between the outer peripheral wall of the rotor 6 and the inner annular wall 91 of the sealing sleeve 9. This gap II communicates with the water-permeable hole 12 to form a water cooling passage (e.g., ...). Figure 2 (As indicated by the dashed arrow).

[0053] The sliding bearing assembly includes a first sliding bearing 13 and a second sliding bearing 14. The first sliding bearing 13 has an annular structure with one end folded towards the center to form a slot 131. The second sliding bearing 14 has an annular structure and is placed in the slot 131, with the two in contact and having a gap I. Both ends of the rotor 6 are provided with annular grooves 61 to accommodate the first sliding bearing 13, which is tightly fitted within the annular grooves 61. A boss 81 protrudes from the outer wall of the structural member 8, and the inner wall of the second sliding bearing 14 is tightly fitted onto the outer wall of one side of the boss 81 and is limited by the boss 81.

[0054] The first sliding bearing 13 is installed in the annular grooves 61 at both ends of the rotor 6. The inner wall of the first sliding bearing 13 is tightly fitted with the outer wall of the rotor 6 and abuts axially with the rotor 6. When the motor assembly is working, the first sliding bearing 13 rotates with the rotor 6. The second sliding bearing 14 is installed on the structural member 8. The inner wall of the second sliding bearing 14 is tightly fitted with the outer wall of one end of the structural member 8 and abuts axially with the radial boss 81 in the middle of the structural member 8. When the motor assembly is working, the second sliding bearing 14 remains fixed. Thus, there will be relative movement between the first sliding bearing 13 and the second sliding bearing 14. Water enters between the first sliding bearing 13 and the second sliding bearing 14 through the water permeable hole, which can prevent the two sliding bearings from dry friction and improve the service life of the two sliding bearings.

[0055] like Figure 5 As shown, propeller blades 7 are evenly distributed inside the rotor 6. The propeller blades 7 and the rotor 6 are an integral structure, which can be connected by adhesive, tight fit, or integral molding. When the shaftless thruster is working, the rotor 6 drives the propeller blades 7 to rotate, generating thrust and propelling the underwater device forward.

[0056] like Figure 6 As shown, the sealing sleeve 9 is a hollow cylinder with an inner ring wall 91 and an outer ring wall 92 on its peripheral wall. One end of the outer ring wall 92 and the inner ring wall 91 are connected to form a stator slot 90 with a circular structure. The stator 5 is tightly fitted inside the stator slot 90. A wire outlet 93 is provided on the outer ring wall 92 of the stator slot 90 away from the opening, facilitating the lead-out of the stator winding. On the sealing sleeve 9 near the wire outlet 93, the inner ring wall 91 and the outer ring wall 92 are connected together to form a U-shaped structure, while the other end of the inner ring wall 91 and the outer ring wall 92 are separated to form an opening, facilitating the insertion of the stator 5 into the stator slot 90. In this embodiment, the stator 5 is a plastic-sealed stator, which has good waterproof and insulating properties. When the small underwater shaftless thruster is working, such as... Figure 2 As shown, water enters through the permeable hole 12, flows through the channel formed by the inner ring wall 91 from the end with the outlet 93, and passes through the sealing sleeve 9. The water and the stator 5 are separated by the inner ring wall 91, which protects the stator 5 winding. At the same time, the water carries away the heat generated by the winding, achieving a liquid cooling effect. Furthermore, the edges of the corresponding openings of the inner ring wall 91 and the outer ring wall 92 are folded inward and outward respectively to form folded edges.

[0057] like Figure 7 As shown, annular grooves 61 are provided at both ends of the rotor 6. The first sliding bearing 13 is respectively installed into the annular grooves 61 at both ends of the rotor 6, and the outer wall of the first sliding bearing 13 is tightly fitted with the inner wall of the annular groove 61. The first sliding bearing 13 and the propeller blade 7 rotate with the rotor 6. The first sliding bearing 13 has a flange facing towards the center at one end near the rotor 6, such as... Figure 2As shown, the cross-sectional view of the first sliding bearing 13 is L-shaped, forming a slot 131 to accommodate the second sliding bearing 14.

[0058] Specifically, axially, the first sliding bearing 13 is placed in the annular groove 61 of the rotor 6, with one end of the first sliding bearing 13 approaching the propeller blade 7 and abutting against the annular groove 61 of the rotor 6; radially, the radially outward end of the first sliding bearing 13 abuts against the annular groove 61, meaning the first sliding bearing 13 and the annular groove 61 are radially tightly fitted together. The second sliding bearing 14 is placed in the groove 131 of the first sliding bearing 13, with the outer circumference of the second sliding bearing 14 and the inner circumference of the first sliding bearing 13 in a loose fit, seemingly in contact but not in contact, allowing them to rotate relative to each other. During operation, the first sliding bearing 13 rotates with the rotor 6, while the second sliding bearing 14 remains stationary; therefore, the inner circumferential surface of the first sliding bearing 13 rubs against the outer circumferential surface of the second sliding bearing 14.

[0059] like Figure 8 and Figure 9 As shown, the second sliding bearing 14 has a ring structure. One end of the structural member 8 is inserted into the inner wall of the second sliding bearing 14, and the two are radially tightly fitted. A boss 81 is provided on the outer periphery of the structural member 8 to limit and fix it axially. Then, the fastener between the structural member 8 and the second sliding bearing 14 is inserted into the groove 131 of the first sliding bearing 13. In this embodiment, the first sliding bearing 13 is preferably a ceramic bearing, and the second sliding bearing 14 is preferably a graphite bearing. When the shaftless thruster is working, the structural member 8 and the second sliding bearing 14 are fixed, and relative movement occurs between the first sliding bearing 13 and the second sliding bearing 14. The graphite powder and water generated by their mutual friction together play a lubricating role. At the same time, the structural member 8 also plays a radial support role, supporting the first sliding bearing 13, the second sliding bearing 14 and the rotor 6 to keep their axial and radial positions fixed, and the four form a concentric structure.

[0060] Specifically, the outer circumferential surface of the structural component 8 abuts against and is tightly fitted with the inner circumferential surface of the second sliding bearing 14. The structural component 8 supports the second sliding bearing 14 in the radial direction, ensuring that the second sliding bearing 14 remains fixed during operation. At the same time, the boss 81 on the outer circumference of the middle part of the structural component 8 plays an axial limiting role. When the second sliding bearing 14 is pressed into the structural component 8, the boss 81 contacts the second sliding bearing 14, indicating that it has been pressed into place.

[0061] The structural component 8 is divided into two ends by the boss 81. One end is tightly fitted with the second sliding bearing 14, and the other end is fixed by the upper cover 1 or the lower cover 3, which ensures that the structural component 8 remains fixed during operation. Figure 10 As shown, during assembly, the boss 81 of the structural component 8 abuts and coincides with the inner wall structure of the lower cover 3 along the axial direction. At this time, the lower edge of the boss 81 is just flush with the edge of the lower cover 3, which plays an axial positioning role during installation.

[0062] like Figure 11 As shown, the upper cover 1 has grooves I15 and II16, with a protrusion between grooves I15 and II16 that tightly fits the opening of the sealing sleeve 9. A first sealing ring 17 is provided in groove I15, and the folded edge of the outer ring wall 92 of the sealing sleeve 9 abuts against the first sealing ring 17. A second sealing ring 18 is provided in groove II16, and the folded edge of the inner ring wall 91 abuts against the second sealing ring 18. Adding two sealing rings to the upper cover 1 improves the overall sealing and waterproofing effect of the shaftless thruster. Figure 10 During assembly, structural component 8 is inserted into the top cover 1, and then sealing sleeve 9 is installed. The upper edge of the outer wall of sealing sleeve 9 abuts against the first sealing ring 17, while the upper edge of the inner wall abuts against the second sealing ring 18, forming a static sealing structure with good sealing effect.

[0063] like Figure 2 As shown, the inner wall of the outer casing 2 is tightly pressed against the outer ring wall 92 of the sealing sleeve 9, and the edge of the inner wall of the outer casing 2 presses against the folded edge of the outer ring wall 92. The upper cover 1 and the lower cover 3 are connected to the outer casing 2 by fastening screws 4. When installing the outer casing 2, align the fastening screw holes of the outer casing 2 with the fastening screw holes of the upper cover 1 for installation. At this time, the edge of the inner wall of the outer casing 2 presses against the folded edge of the outer ring wall 92. After the upper cover 1 is fixed with the fastening screws 4, the upper edge of the inner wall of the outer casing 2 and the folded edge of the outer ring wall 92 can press against the first sealing ring 17, and the folded edge of the inner ring wall 91 tightly presses against the second sealing ring 18, achieving a good sealing and waterproof effect.

[0064] This embodiment of the small underwater shaftless thruster effectively prevents water from entering the motor assembly, protecting it from water corrosion and improving the thruster's reliability and service life. The sealed cavity design can withstand a certain water pressure, making it suitable for use in deep-water environments and ensuring the motor assembly can still operate normally under high pressure. Water enters gap I through the water permeation hole 12, providing lubrication for the sliding bearing, reducing friction loss and extending bearing life. The water lubrication path uses water as the lubricating medium, eliminating the need for additional lubricating oil or grease, reducing maintenance requirements, and is particularly suitable for underwater use. The water cooling path uses water as the cooling medium, eliminating the need for an additional cooling system, simplifying the thruster's structure, and improving cooling efficiency. Water enters gap II through the water permeation hole 12, flowing through the motor assembly and carrying away the heat generated during motor operation, effectively preventing motor overheating.

[0065] The design of the inlet 31 and outlet 11 allows for bidirectional water flow. Water can enter the propeller through the inlet 31 for lubrication and cooling, and exit through the outlet 11, ensuring smooth water circulation within the propeller. The sliding bearing assembly design enables the rotor 6 to operate under low friction, reducing energy loss and improving propeller efficiency. The water-lubricated sliding bearing assembly reduces mechanical wear, extends bearing life, and lowers maintenance frequency.

[0066] Example 2

[0067] like Figure 13 As shown, the difference from Embodiment 1 is that the outer end face of the top cover 1 is an arc surface. The arc surface of the top cover 1 can effectively slow down the water flow speed, so that the water will not spray out directly when it flows out, but will be guided by the arc shape, thereby reducing the impact force of the water flow and making the water flow more even, avoiding the water flow from being too concentrated or dispersed.

[0068] Example 3

[0069] like Figure 14 As shown, the difference from Embodiment 1 is that the outer end face of the lower cover 3 is an arc surface. The arc surface of the lower cover 3 can reduce water flow resistance. The arc surface of the lower cover 3 can effectively guide the water flow, making it enter the inlet 31 more evenly, avoiding excessive concentration or dispersion of water flow, thereby reducing water flow impact; it can reduce the direct impact of water flow on the inlet 31, reduce noise caused by excessive water flow speed, and make the water flow more stable; it can better disperse water flow pressure, avoid local stress concentration caused by water flow impact, thereby improving the structural strength and durability of the inlet 31.

[0070] Example 4

[0071] The difference from Embodiment 1 is that the outer end faces of both the upper cover 1 and the lower cover 3 are arc surfaces.

[0072] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A small underwater shaftless propulsion device, comprising a housing (2) and a motor assembly located within the housing (2), wherein an upper cover (1) and a lower cover (3) are respectively provided at both ends of the housing (2), and through holes are respectively provided in the middle of the lower cover (3) and the upper cover (1) to form a water inlet (31) and a water outlet (11), the motor assembly comprising a stator (5) and a rotor (6), the stator (5) being located radially outside the rotor (6), and a propeller blade (7) being provided inside the rotor (6), characterized in that: The stator (5) is annular and is disposed in a sealing sleeve (9). One end of the sealing sleeve (9) is open and the opening is covered and sealed by the upper cover (1) to form a sealed cavity. The sealing sleeve (9) is a hollow cylinder with an inner ring wall (91) and an outer ring wall (92) on its periphery. One end of the outer ring wall (92) and the inner ring wall (91) are connected to form a stator groove (90) with a circular structure. The stator (5) is tightly fitted in the stator groove (90).

2. A small underwater shaftless thruster according to claim 1, characterized in that: The outer ring wall (92) has an outlet (93) at the end away from the opening.

3. A small underwater shaftless thruster according to claim 1, characterized in that: The edges of the corresponding openings of the inner ring wall (91) and the outer ring wall (92) are folded inward and outward respectively to form folded edges.

4. A small underwater shaftless thruster according to claim 1, characterized in that: The upper cover (1) is provided with groove I (15) and groove II (16), and a protrusion is formed between groove I (15) and groove II (16) to fit tightly with the opening of the sealing sleeve (9).

5. A small underwater shaftless thruster according to claim 4, characterized in that: The groove I (15) is provided with a first sealing ring (17), and the folded edge of the outer ring wall (92) abuts against the first sealing ring (17); the groove II (16) is provided with a second sealing ring (18), and the folded edge of the inner ring wall (91) abuts against the second sealing ring (18).

6. A small underwater shaftless thruster according to claim 5, characterized in that: The inner wall of the outer shell (2) is tightly against the outer ring wall (92) of the sealing sleeve (9), and the edge of the inner wall of the outer shell (2) is pressed against the folded edge of the outer ring wall (92).

7. A small underwater shaftless thruster according to claim 1, characterized in that: Water-permeable holes (12) are provided on the lower cover (3) near the water inlet (31) and the upper cover (1) near the water outlet (11). A structural component (8) is provided on the water inlet (31) and the water outlet (11). A sliding bearing assembly is provided between the structural component (8) and the rotor (6). The sliding bearing assembly has a gap I inside, which is connected to the water-permeable hole (12) to form a water lubrication passage.

8. A small underwater shaftless thruster according to claim 7, characterized in that: The sliding bearing assembly includes a first sliding bearing (13) and a second sliding bearing (14). The first sliding bearing (13) has a ring structure and one end is folded towards the center to form a groove (131). The second sliding bearing (14) has a ring structure and is placed in the groove (131). The two are in contact and have a gap I.

9. A small underwater shaftless thruster according to claim 8, characterized in that: The rotor (6) has annular grooves (61) at both ends to accommodate the first sliding bearing (13), and the first sliding bearing (13) is tightly fitted in the annular grooves (61).

10. A small underwater shaftless thruster according to claim 8, characterized in that: A boss (81) is formed on the outer wall of the structural member (8), and the inner wall of the second sliding bearing (14) is tightly fitted on the outer wall of one side of the boss (81) and is limited by the boss (81).

11. A small underwater shaftless thruster according to claim 10, characterized in that: The outer wall of the other side of the boss (81) mates with the inner wall of the upper cover (1) or the lower cover (3).

12. A small underwater shaftless thruster according to claim 8, characterized in that: The first sliding bearing (13) is a ceramic bearing, and the second sliding bearing (14) is a graphite bearing.

13. A small underwater shaftless thruster according to claim 1, characterized in that: There is a gap II between the outer peripheral wall of the rotor (6) and the inner ring wall of the sealing sleeve (9), which is connected to the water-permeable hole (12) to form a water cooling passage.

14. A small underwater shaftless thruster according to claim 1, characterized in that: The stator (5) is a plastic-sealed stator.

15. A small underwater shaftless thruster according to claim 1, characterized in that: The rotor (6) has several propeller blades (7) evenly distributed inside. The propeller blades (7) and the rotor (6) are connected by adhesive bonding, tight fit, or integral molding.

16. A small underwater shaftless thruster according to claim 1, characterized in that: The outer casing (2) has a cable outlet hole (21), and the upper cover (1) and lower cover (3) are connected to the outer casing (2) by fastening screws (4).

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