Submersible sewage pump with internal circulation heat dissipation

Abstract

The application discloses a submersible sewage pump with internal circulation heat dissipation, which comprises a volute, a centrifugal impeller rotatably arranged in the volute, a motor with a motor shell and a motor output shaft coaxially connected with the centrifugal impeller, the motor shell being provided with a first cooling cavity, a connecting seat fixed between the volute and the motor shell, the connecting seat being hollow and internally provided with an impeller for driving the cooling liquid to flow from top to bottom, the connecting seat being provided with a circulating inlet channel communicating with the upper end of the inner cavity of the connecting seat and a circulating outlet channel communicating with the lower end of the inner cavity of the connecting seat, and the end surface of the volute facing the connecting seat being provided with a first heat exchange structure, wherein the first heat exchange structure comprises a first guide structure and a second guide structure, the first guide structure is opposite to the impeller, the first guide structure guides the cooling liquid to the second guide structure, and the second guide structure guides the cooling liquid to the inlet end of the circulating outlet channel directly below. The application has good heat dissipation effect.

Description

Technical Field

[0001] This invention relates to the field of sewage pumps, and in particular to a submersible sewage pump with internal circulation cooling. Background Technology

[0002] A submersible sewage pump is a type of pump that tightly couples the pump and motor, allowing them to operate entirely submerged in liquid. It is primarily used to transport sewage, wastewater, rainwater, and even sludge containing impurities such as solid particles, fibers, feces, and paper. Due to its unique operating environment, it boasts advantages such as compact structure, no need for priming, easy installation, and noiseless operation, making it an indispensable piece of equipment in municipal, construction, industrial, and agricultural fields.

[0003] Previous submersible sewage pumps had internal cooling channels. Water discharged from the volute was introduced into these channels via pipes for cooling, and the pump was also cooled by immersing it in water. However, the water used by these pumps contained many impurities, which easily accumulated in the cooling channels, clogging them and severely hindering heat dissipation. To address this issue, current submersible sewage pumps incorporate an internal coolant circulation mechanism. This mechanism drives the coolant to circulate along an internal cooling channel. Because a section of this internal cooling channel is close to the volute, the coolant transfers heat absorbed from the motor to the water passing through the volute via heat conduction through the side walls, thus achieving heat dissipation without external water cooling. However, the coolant flow rate is too high in this section of the internal cooling channel near the volute, resulting in low heat exchange efficiency. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a submersible sewage pump with internal circulation heat dissipation, which has the advantage of good heat dissipation effect.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A submersible sewage pump with internal circulation cooling includes:

[0007] Snail shell;

[0008] A centrifugal impeller is rotatably mounted inside the volute casing;

[0009] An electric motor has a motor housing and a motor output shaft, the motor output shaft being coaxially connected to the centrifugal impeller, and the motor housing having a first cooling chamber;

[0010] The connecting seat is fixed between the volute and the motor housing. It is hollow and has an impeller inside that drives the coolant to flow from top to bottom. It has a circulation inlet channel connecting the first cooling chamber and the upper end of the inner cavity of the connecting seat, and a circulation outlet channel connecting the first cooling chamber and the lower end of the inner cavity of the connecting seat.

[0011] A first heat exchange structure is provided on the end face of the volute facing the connecting seat; the first heat exchange structure includes a first guiding structure and a second guiding structure; the first guiding structure is directly opposite the impeller; the first guiding structure guides the coolant to the second guiding structure, and the second guiding structure guides the coolant directly below the inlet end of the circulation outflow channel.

[0012] By adopting the above technical solution, when the motor is working, the coolant in the first cooling chamber absorbs the heat generated by the motor. The impeller on the motor output shaft rotates, driving the coolant to flow as a whole. That is, the coolant, having absorbed the heat generated by the motor, flows from the first cooling chamber into the upper part of the inner cavity of the connecting seat along the circulation inlet channel. Then, under the action of the impeller, it flows from top to bottom. Afterward, guided by the first guide structure, it enters the second guide structure. The second guide structure directs the coolant directly below the inlet end of the circulation outlet channel. Since the pressure at the lower end of the inner cavity of the connecting seat is greater than the pressure in the first cooling chamber, the coolant will then flow back to the first cooling chamber along the circulation outlet channel. Due to the presence of the second guide structure, the heat exchange area between the coolant and the side wall of the volute near the connecting seat is greatly increased, thereby improving heat exchange efficiency and heat dissipation. At the same time, the rotation of the centrifugal impeller exerts a downward pull on the motor output shaft, while the impeller drives the coolant to spray downward, thus giving the motor output shaft an upward thrust. This balances the axial force of the motor output shaft to a certain extent, reducing the axial force on the bearings used for rotational support, and reducing bearing wear and heat generation.

[0013] Optionally, the first guide structure is a conical housing coaxial with the motor output shaft, and the end of this conical housing closer to the impeller is smaller than the end farther from the impeller.

[0014] By adopting the above technical solution, the conical surface of the conical shell, which is smaller at the top and larger at the bottom, guides the coolant to tilt downwards into the second guiding structure. During this process, the conical surface of the conical shell increases the contact area with the coolant, thereby improving heat dissipation efficiency. At the same time, a bearing for supporting the output shaft can be installed inside the conical shell. The heat generated by the bearing during operation can be directly transferred to the first heat exchange structure, thereby improving heat exchange efficiency.

[0015] Optionally, the second guide structure includes a plurality of concentric rings coaxial with the motor output shaft; all of the concentric rings are open at one end near the circulating outflow channel.

[0016] By adopting the above technical solution, the coolant flows along the gap between two adjacent concentric rings. This increases the contact between the coolant and the inner and outer cylindrical surfaces of the concentric rings during the flow process, relative to the plane, thereby increasing the contact area between the coolant and the side wall of the volute near the connecting seat. At the same time, the concentric rings are opened at one end near the circulation outlet channel, which creates a height difference that causes the coolant between the two adjacent concentric rings to flow towards the opening near the circulation outlet channel.

[0017] Optionally, both ends of the opening of the concentric ring are bent outwards in an arc.

[0018] By adopting the above technical solution, both ends of the opening of the concentric ring are bent outward in an arc, which improves the smoothness of coolant flow and reduces energy loss.

[0019] Optionally, the two ends of the openings of all the concentric rings are located on the same circle.

[0020] By adopting the above technical solution, the two ends of the openings of all concentric rings are located on the same circle, avoiding obstruction of the coolant flowing out between two adjacent concentric rings.

[0021] Optionally, the second guide structure further includes an outer retaining ring; the outer retaining ring is coaxial with the motor output shaft and all concentric rings are located inside the outer retaining ring.

[0022] By adopting the above technical solution, the outer baffle ring further increases the heat dissipation contact area of ​​the coolant, while blocking the horizontal flow of coolant between two adjacent concentric rings, so that the coolant that has undergone heat exchange can enter the circulation outflow channel more quickly.

[0023] Optionally, a second heat exchange structure is provided on the inner side wall of the volute near the connecting seat.

[0024] By adopting the above technical solution, a second heat exchange structure is provided on the inner side wall of the volute near the connecting seat, which increases the heat exchange area between the side wall of the volute near the connecting seat and the water flowing through the volute, thereby improving the heat dissipation efficiency.

[0025] Optionally, the volute includes an oil chamber cover and a volute body; the oil chamber cover is detachably connected between the connecting seat and the volute body; the oil chamber cover separates the internal space of the connecting seat and the internal space of the volute body; the first heat exchange structure is located on the end face of the oil chamber cover facing the connecting seat; the second heat exchange structure is located on the end face of the oil chamber cover facing the volute body.

[0026] By adopting the above technical solution, the oil chamber cover, as an independent component, facilitates processing. At the same time, it can be detachably connected to the connecting seat and the volute body, greatly improving the convenience of maintenance and replacement of the oil chamber cover.

[0027] Optionally, the connecting seat is provided with a first partition and a middle partition distributed vertically to divide its internal space into an upper cooling chamber, a lower cooling chamber, and a third cooling chamber distributed from top to bottom; the circulation inlet channel connects the first cooling chamber and the lower cooling chamber; the upper cooling chamber is filled with heat transfer oil; the middle partition is formed with a liquid inlet hole that mates with the impeller; a first mechanical seal is provided between the side wall of the connecting seat near the motor housing and the motor output shaft; a second mechanical seal is provided between the first partition and the motor output shaft; and a third mechanical seal is provided between the volute and the side wall of the connecting seat near the motor output shaft.

[0028] By adopting the above technical solution, compared with two mechanical seals, the three mechanical seals of the first, second and third mechanical seals greatly increase the sealing performance and effectively reduce the possibility of water entering the motor. At the same time, since the upper cooling cavity is filled with heat transfer oil, the heat generated by the motor operation will be absorbed by the heat transfer oil. Compared with heat transfer through the side wall, the heat exchange efficiency is higher, which further improves the heat dissipation efficiency.

[0029] Optionally, a pressure sensor is installed in the upper cooling chamber; the pressure sensor is used to control the motor to stop rotating.

[0030] By adopting the above technical solution, when the first or second mechanical seal fails, the pressure sensor in the upper cooling chamber will detect the pressure change, thereby controlling the motor to stop working, avoiding damage caused by liquid entering the motor, and greatly improving the working safety of the motor. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the present invention.

[0032] Figure 2 This is a cross-sectional structural schematic diagram of the present invention.

[0033] Figure 3 This is a cross-sectional structural schematic diagram of the present invention.

[0034] Figure 4 This is a schematic diagram of the upper side of the oil chamber cover of the present invention.

[0035] Figure 5 This is a top view of the oil chamber cover of the present invention.

[0036] Figure 6 This is a schematic diagram of the structure of the lower side of the oil chamber cover of the present invention.

[0037] Figure 7 This is a schematic diagram of the structure of the oil chamber cover according to another embodiment of the present invention.

[0038] Figure 8 This is the invention Figure 7 A magnified structural diagram of part A in the diagram.

[0039] Explanation of reference numerals in the attached figures:

[0040] 10. Motor; 100. First cooling chamber; 11. Motor housing; 111. Inner housing; 112. Outer housing; 113. Outer end cover; 114. Water inlet pipe; 12. Stator; 13. Motor output shaft; 131. Impeller connection part; 132. Screw part; 14. Rotor; 15. Impeller;

[0041] 20. Connecting seat; 200. Second cooling chamber; 201. Third cooling chamber; 202. Upper cooling chamber; 203. Lower cooling chamber; 21. Connecting seat body; 210. Circulation inlet channel; 211. Circulation outlet channel; 22. Intermediate partition; 220. Liquid inlet hole; 23. First partition;

[0042] 30. Oil chamber cover; 31. First heat exchange structure; 311. First guide structure; 312. Second guide structure; 313. Concentric ring; 314. Heat exchange channel; 3141. Guide surface; 315. Outer retaining ring; 316. End boss; 32. Second heat exchange structure; 321. Heat exchange ring;

[0043] 40. Volute body;

[0044] 50. Centrifugal impeller;

[0045] 60. First machine seal;

[0046] 70. Second machine seal;

[0047] 80. Third machine seal;

[0048] 90. Pressure sensor. Detailed Implementation

[0049] The following is in conjunction with the appendix Figures 1-8 The present invention will be described in further detail below.

[0050] Example 1: A submersible sewage pump with internal circulation cooling is disclosed, referencing... Figure 1The submersible sewage pump includes a motor 10, a connecting seat 20, an oil chamber cover 30, a volute body 40, and a centrifugal impeller 50. The oil chamber cover 30 and the volute body 40 form a complete volute. The motor 10 includes a motor housing 11, a stator 12 fixed to the inner wall of the motor housing 11, a motor output shaft 13 rotatably connected within the motor housing 11, and a rotor 14 fixed to the motor output shaft 13. The motor housing 11, connecting seat 20, oil chamber cover 30, and volute body 40 are sequentially distributed along the axial direction of the motor output shaft 13, and adjacent components are connected by flanges and sealed by sealing rings. The motor output shaft 13 passes sequentially through the connecting seat 20 and the oil chamber cover 30, and its end is fixedly connected to the centrifugal impeller 50 within the volute body 40. When the submersible sewage pump is working, it is generally installed vertically, meaning the motor 10 is located above the volute body 40.

[0051] refer to Figure 2 and Figure 3 The motor housing 11 includes an inner housing 111, an outer housing 112, and an outer end cover 113; the stator 12 is fixed to the inner wall of the inner housing 111; the inner housing 111 and the outer housing 112 are coaxially arranged, and one end of the inner housing 111 is fixed to the end of the connecting seat 20 by bolts, and the other end is fixed to the outer end cover 113 by bolts, so that the outer end cover 113, the inner housing 111, the outer housing 112, and the connecting seat 20 form a first cooling cavity 100 in the shape of an annular cylindrical groove surrounding the inner housing 111.

[0052] refer to Figure 2 and Figure 3 The connecting seat 20 includes a connecting seat body 21; the connecting seat body 21 is hollow inside and has an opening at the lower end; a middle partition plate 22 is fixed inside the connecting seat body 21 by bolts; the middle partition plate 22 divides the internal space of the connecting seat body 21 into a second cooling chamber 200 close to the motor housing 11 and a third cooling chamber 201 away from the motor housing 11; the second cooling chamber 200 and the third cooling chamber 201 are distributed along the axial direction of the motor output shaft 13; a circulation inlet channel 210 and a circulation outlet channel are formed inside the connecting seat body 21. Channel 211; the circulating inlet channel 210 and the circulating outlet channel 211 are evenly distributed around the circumference; the circulating inlet channel 210 connects the first cooling chamber 100 and the second cooling chamber 200; the circulating outlet channel 211 connects the third cooling chamber 201 and the first cooling chamber 100; to improve the heat exchange efficiency of the coolant, a water inlet pipe 114 is screwed onto the bottom surface of the first cooling chamber 100; the lower opening of the water inlet pipe 114 is connected to the upper opening of the circulating inlet channel 210, and the upper opening is located in the upper part of the first cooling chamber 100. To facilitate the entry of coolant into the water inlet pipe 114, the upper end surface of the water inlet pipe 114 is formed with an inclined surface, and this inclined surface is inclined downward along the direction away from the motor output shaft.

[0053] refer to Figure 2 and Figure 3 In order to achieve internal circulation of coolant, an impeller 15 is fixed on the motor output shaft 13 and is coaxially arranged. The center of the intermediate partition 22 is formed with a liquid inlet hole 220 that runs vertically through it. The liquid inlet hole 220 is coaxially arranged with the motor output shaft 13. The impeller 15 is located inside the liquid inlet hole 220. During operation, the motor drives the output shaft 13 to rotate, which in turn drives the centrifugal impeller 50 and impeller 15 to rotate synchronously. The centrifugal impeller 50 increases the kinetic energy of the water, and then the volute body 40 converts the kinetic energy into pressure energy, thus giving the water sufficient pressure. The impeller 15 causes the coolant to circulate. Specifically, the coolant in the first cooling chamber 100 absorbs the heat from the operation of the motor 10, and then enters the second cooling chamber 200 along the water inlet pipe 114 and the circulation inlet channel 210. Then, it passes from top to bottom through the liquid inlet hole 220 where the impeller 15 is located and enters the third cooling chamber 201. At this time, the coolant exchanges heat with the water flowing through the volute body 40 through the oil chamber cover 30 to achieve cooling. Since the pressure in the third cooling chamber 201 is greater than the pressure in the first cooling chamber 100, the cooled coolant will flow back to the first cooling chamber 100 through the circulation outlet channel 211 to reabsorb the heat from the operation of the motor 10.

[0054] When the centrifugal impeller 50 rotates, it will exert a downward pulling force on the motor output shaft 13, while the impeller 15 drives the coolant to spray downward, thereby giving the motor output shaft 13 an upward thrust. This balances the axial force of the motor output shaft 13 to a certain extent, reduces the axial force of the bearing used for rotational support, and reduces bearing wear and heat generation.

[0055] refer to Figures 2-5 In order to improve the heat exchange efficiency of the oil chamber cover 30, a first heat exchange structure 31 is provided on the wall of the oil chamber cover 30 near the third cooling chamber. The first heat exchange structure 31 includes a first guide structure 311 and a second guide structure 312. The first guide structure 311 is directly opposite the impeller 15 and is used to guide the coolant sprayed from the liquid inlet 220 to the second guide structure 312. The second guide structure 312 guides the coolant to the area directly below the inlet end of the circulation outlet channel 211.

[0056] refer to Figure 4 and Figure 5The first guiding structure 311 is a conical shell protruding from the middle of the oil chamber cover 30 toward the third cooling chamber 201. This conical shell is coaxial with the motor output shaft 13, and its end near the impeller 15 is smaller than its end away from the impeller 15. The second guiding structure 312 surrounds the large-diameter end of the conical shell. The conical surface on the outer side of the conical shell not only serves as a guide but also increases the contact area between the coolant and the oil chamber cover 30, thereby improving heat exchange efficiency. In other embodiments, multiple circumferentially evenly distributed and radially arranged fins can be provided on the conical surface on the outer side of the conical shell. In this way, when the coolant flows over the conical surface on the outer side of the conical shell, the fins can absorb more heat, thereby improving heat exchange efficiency.

[0057] refer to Figure 4 and Figure 5 The second guiding structure 312 includes several concentric rings 313 coaxial with the motor output shaft 13; all concentric rings 313 are open at one end near the circulation outlet channel 211. The gap between two adjacent concentric rings 313 forms a heat exchange channel 314. When the coolant flows along the heat exchange channel 314, compared to heat exchange with a flat surface, the contact area with the inner and outer cylindrical surfaces of the concentric rings 313 is increased, thereby increasing the contact area between the coolant and the oil chamber cover 30. Simultaneously, because the concentric rings 313 are open at one end near the circulation outlet channel 211, a high-low pressure difference is created, causing the coolant in the heat exchange channel 314 to flow towards the opening near the circulation outlet channel 211. To improve the smoothness of coolant flow out of the heat exchange channel 314 and reduce its power loss, both ends of the opening of the concentric rings 313 are bent outwards in an arc. To prevent the ends of the openings of the concentric rings 313 from blocking the openings of the adjacent heat exchange channels 314, both ends of the openings of all the concentric rings 313 are located on the same circle.

[0058] refer to Figure 4 and Figure 5 In order to allow the coolant flowing out of the heat exchange channel 314 to quickly enter the circulation outlet channel 211, the second guide structure 312 also includes an outer baffle ring 315. The outer baffle ring 315 is coaxial with the motor output shaft 13 and all the concentric rings 313 are located inside the outer baffle ring 315. The gap between the outer baffle ring 315 and the outermost concentric ring 313 also forms the heat exchange channel 314. In this way, the outer baffle ring 315 can block the horizontal flow of the coolant that has completed heat exchange, so that it can enter the circulation outlet channel 211 more quickly.

[0059] refer to Figure 7 and Figure 8In other embodiments, the circumference of the openings of all concentric rings 313 and the outer retaining ring 315 form an end boss 316; the upper surface of the end boss 316 is flush with the upper surfaces of all concentric rings 313; a guide surface 3141 is provided between the bottom surface of the heat exchange channel 314 and the top surface of the end boss 316; the guide surface 3141 can be an inclined surface or a curved surface; to improve flow smoothness, the guide surface 3141 smoothly transitions to the three sidewalls of the heat exchange channel 314. During operation, the coolant flowing out from the outlet of the heat exchange channel 314 will be guided by the guide surface 3141 to better converge and flow towards the opening of the circulation outlet channel 211.

[0060] refer to Figure 6 To further improve the heat exchange efficiency of the oil chamber cover 30, a second heat exchange structure 32 is provided on the wall surface of the oil chamber cover 30 inside the volute body 40; the second heat exchange structure 32 consists of several concentric heat exchange rings 321 that are coaxial with the motor output shaft 13. The cross-section of the heat exchange rings 321 is an isosceles trapezoid.

[0061] refer to Figure 2 and Figure 3 To improve the rotational stability of the motor output shaft 13, at least two axially distributed bearings are provided between the motor output shaft 13 and the side wall of the connecting seat body 21 near the motor 10, and at least two axially distributed bearings are provided between the motor output shaft 13 and the oil chamber cover 30. Simultaneously, mounting grooves for installing bearings are formed on the outer wall surface of the motor output shaft 13 and the side wall of the connecting seat body 21 near the motor 10. This allows the heat generated by these bearings during operation to be carried away by the coolant flowing through the second cooling chamber 200. Furthermore, the bearing between the motor output shaft 13 and the oil chamber cover 30 is located within the first guide structure 311, allowing the heat generated by these bearings during operation to be carried away by the coolant flowing through the first guide structure 311, thus facilitating heat dissipation. To improve axial load-bearing capacity, angular contact ball bearings or tapered roller bearings are used.

[0062] refer to Figure 2 and Figure 3 To improve sealing, a first mechanical seal 60 is installed between the motor output shaft 13 and the side wall of the connecting seat body 21 near the motor 10, and a third mechanical seal 80 is installed between the motor output shaft 13 and the oil chamber cover 30.

[0063] In Example 1, since the submersible sewage pump is cooled by internal circulation of coolant, the heat exchange effect is good. Therefore, when the submersible sewage pump is working, only the volute body 40 needs to be submerged in water, while the motor housing 11 of the motor 10 can be exposed above the water surface. That is, there is no need to cool the motor housing 11 by contacting water. This reduces the possibility of the motor housing 11 being corroded by sewage, improves its service life, and also reduces the possibility of water entering the motor 10.

[0064] Example 2: The difference between Example 2 and Example 1 is as follows: (Refer to...) Figure 2 and Figure 3 A first partition 23 is bolted inside the connecting seat body 21, dividing the second cooling chamber 200 into an upper cooling chamber 202 and a lower cooling chamber 203 distributed axially along the motor output shaft 13. The upper cooling chamber 202 is close to the motor housing 11, while the lower cooling chamber 203 is away from the motor housing 11. A circulation channel 210 connects the first cooling chamber 100 and the lower cooling chamber 203. The upper cooling chamber 202 is filled with heat-conducting oil. A second mechanical seal 70 is installed between the motor output shaft 13 and the first partition 23. Because the upper cooling chamber 202 is filled with heat-conducting oil, the heat generated by the motor 10 is absorbed by the oil, resulting in higher heat exchange efficiency compared to sidewall heat transfer, further improving heat dissipation efficiency. The mechanical seals in the first mechanical seal 60, the second mechanical seal 70, and the third mechanical seal 80 are all mechanical seals.

[0065] In Embodiment 1, when the first mechanical seal 60 used to isolate the coolant fails, the coolant directly enters the motor 10; in Embodiment 2, when the second mechanical seal 70 used to isolate the coolant fails, the coolant enters the upper cooling chamber 202 instead of directly entering the motor 10, thus achieving buffering. This further improves the sealing performance and effectively reduces the possibility of water entering the motor 10.

[0066] To prevent the failure of the second mechanical seal 70 from affecting the motor 10, a pressure sensor 90 is installed in the upper cooling chamber 202; the pressure sensor 90 is used to control the motor 10. When the first mechanical seal 60 or the second mechanical seal 70 fails, the pressure sensor 90 in the upper cooling chamber 202 will detect the pressure change, thereby controlling the motor 10 to stop working, preventing liquid from entering the motor 19 and causing damage, and greatly improving the working safety of the motor 10.

[0067] Example 3: The difference between Example 3 and Example 1 is as follows: (Refer to...) Figure 2 and Figure 3The motor output shaft 13 has an impeller connecting portion 131 for mounting the centrifugal impeller 50 and a screw portion 132 for connecting a fastening nut at its end. The screw portion 132 is located on the side of the impeller connecting portion 131 away from the motor housing 11. The circumferential surface of the impeller connecting portion 131 is a conical surface, and its diameter gradually increases in the direction away from the screw portion 132. The impeller connecting portion 131 and the centrifugal impeller 50 are circumferentially positioned by a key. When the centrifugal impeller 50 is installed, as the fastening nut is tightened, the centrifugal impeller 50 will move closer and closer along the axial direction of the conical surface. In addition, since the circumferential surface of the impeller connecting portion 131 is a conical surface, it is not necessary to machine a relief groove, because when the tool is fed axially, the tool simultaneously retracts radially, thus producing a conical surface. Since there is no relief groove, stress concentration will not occur, and the strength of the motor output shaft 13 is greater.

[0068] In other embodiments, considering the replacement of coolant, an inlet hole can be provided on the outer casing 112, and an inlet plug is screwed into the inlet hole. The number of inlet holes can be set to multiple and distributed circumferentially. An outlet hole is provided on the side wall of the connecting seat body 21 located in the third cooling chamber 201. An outlet plug is connected to the outlet hole. The number of outlet holes can be set to multiple and distributed circumferentially. When replacing coolant, the outlet plug is removed to open the outlet hole, allowing coolant to leak out. Then the outlet plug is reinstalled, and the inlet plug is removed again to open the inlet hole, through which new coolant is injected.

[0069] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A submersible sewage pump with internal circulation cooling, comprising: Snail shell; A centrifugal impeller (50) is rotatably mounted inside the volute casing; The motor (10) has a motor housing (11) and a motor output shaft (13), the motor output shaft (13) being coaxially connected to the centrifugal impeller (50), and the motor housing (11) having a first cooling chamber (100). The connecting seat (20) is fixed between the volute and the motor housing (11), and is hollow and has an impeller (15) inside that drives the coolant to flow from top to bottom. It has a circulation inlet channel (210) connecting the first cooling chamber (100) and the upper end of the inner cavity of the connecting seat (20), and a circulation outlet channel (211) connecting the first cooling chamber (100) and the lower end of the inner cavity of the connecting seat (20). The features are as follows: a first heat exchange structure (31) is provided on the end face of the volute facing the connecting seat (20); the first heat exchange structure (31) includes a first guide structure (311) and a second guide structure (312); the first guide structure (311) is directly opposite the impeller (15); the first guide structure (311) guides the coolant to the second guide structure (312), and the second guide structure (312) guides the coolant to the inlet end of the circulation outlet channel (211) directly below; the second guide structure (312) includes a plurality of concentric rings (313) coaxial with the motor output shaft (13); all the concentric rings (313) are open at one end near the circulation outlet channel (211); Both ends of the opening of the concentric ring (313) are bent outward in an arc; both ends of the opening of all the concentric rings (313) are located on the same circle.

2. The submersible sewage pump with internal circulation heat dissipation according to claim 1, characterized in that: The first guide structure (311) is a conical housing coaxial with the motor output shaft (13), and the end of this conical housing closer to the impeller (15) is smaller than the end farther away from the impeller (15).

3. A submersible sewage pump with internal circulation cooling according to claim 2, characterized in that: The second guide structure (312) further includes an outer retaining ring (315); the outer retaining ring (315) is coaxial with the motor output shaft (13) and all concentric rings (313) are located inside the outer retaining ring (315).

4. A submersible sewage pump with internal circulation cooling according to claim 1, characterized in that: A second heat exchange structure (32) is provided on the inner side wall of the volute near the connecting seat (20).

5. A submersible sewage pump with internal circulation cooling according to claim 4, characterized in that: The volute includes an oil chamber cover (30) and a volute body (40); the oil chamber cover (30) is detachably connected between the connecting seat (20) and the volute body (40); the oil chamber cover (30) separates the internal space of the connecting seat (20) and the internal space of the volute body (40); the first heat exchange structure (31) is located on the end face of the oil chamber cover (30) facing the connecting seat (20); the second heat exchange structure (32) is located on the end face of the oil chamber cover (30) facing the volute body (40).

6. A submersible sewage pump with internal circulation cooling according to claim 1, characterized in that: The connecting seat (20) is provided with a first partition (23) and a middle partition (22) distributed vertically, which divide its internal space into an upper cooling chamber (202), a lower cooling chamber (203) and a third cooling chamber (201) distributed from top to bottom; the circulation inlet channel (210) connects the first cooling chamber (100) and the lower cooling chamber (203); the upper cooling chamber (202) is filled with heat transfer oil; the middle partition (22) is formed with an inlet hole (220) that cooperates with the impeller (15); a first mechanical seal (60) is provided between the side wall of the connecting seat (20) near the motor housing (11) and the motor output shaft (13); a second mechanical seal (70) is provided between the first partition (23) and the motor output shaft (13); a third mechanical seal (80) is provided between the side wall of the volute near the connecting seat (20) and the motor output shaft (13).

7. A submersible sewage pump with internal circulation cooling according to claim 6, characterized in that: A pressure sensor (90) is installed in the upper cooling chamber (202); the pressure sensor (90) is used to control the motor (10) to stop rotating.

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