Permanent magnet mining explosion-proof submersible pump and mounting assembly process thereof

Abstract

The application relates to the technical field of coal mine underground drainage explosion-proof equipment, in particular to a permanent magnet mine explosion-proof submersible electric pump and an installation and assembly process thereof. The permanent magnet mine explosion-proof submersible electric pump comprises an explosion-proof shell assembly, a cable incoming line sealing assembly, a double-end bearing support assembly, a permanent magnet driving unit and a hydraulic pumping assembly. The double-end bearing support assembly is fixedly installed in the installation cavity of the explosion-proof shell assembly, the permanent magnet driving unit is coaxially installed in the double-end bearing support assembly, the outer portion of the permanent magnet driving unit is connected with the double-end bearing support assembly, the lower end of the permanent magnet driving unit extends into the installation cavity below the double-end bearing support assembly and is coaxially connected with the hydraulic pumping assembly. The permanent magnet synchronous explosion-proof rotor and stator structure with a synchronous frequency conversion driving device is adopted, the motor efficiency is increased by 40%-50% compared with the traditional asynchronous submersible pump, the power factor is high, there is no invalid excitation loss, the flow and the lift are dynamically adjusted according to the underground water gushing condition, and the working condition adaptation range is wider.

Description

Technical Field

[0001] This invention relates to the field of explosion-proof equipment for underground drainage in coal mines, and specifically designs a submersible electric pump that is mainly suitable for underground mining, roadway construction, water tank dredging and emergency drainage conditions where there is an explosive mixture of methane and coal dust. In particular, it is a permanent magnet explosion-proof submersible electric pump for mining and its installation and assembly process. Background Technology

[0002] During underground coal mining, water continuously flows from roadways, working faces, and abandoned mining pits. Accumulated water can submerge mining equipment, soften surrounding rock, and cause collapses. Therefore, continuous drainage equipment must be provided.

[0003] Most of the mainstream downhole drainage equipment in the industry currently uses asynchronous motors to drive explosion-proof submersible pumps with a speed of about 1500 r / min, and is mainly started by direct power frequency; its overall structure is an upper pump body, and the sealing system mostly uses a single mechanical seal.

[0004] When existing asynchronous submersible pumps are used in coal mine rescue operations involving high levels of sediment and confined spaces, with frequent start-stop cycles and emergency response conditions, the following problems typically arise:

[0005] First, asynchronous motors have high excitation losses and low overall operating efficiency. Underground drainage requires 24-hour continuous operation, resulting in high energy costs over the long term. Furthermore, the low speed design of 1500r / min leads to large hydraulic components in the pump body and a heavy overall machine, making it difficult to transport equipment in narrow underground tunnels and deploy it quickly for emergency rescue. Most motors lack frequency conversion adaptability and have fixed speeds. When faced with fluctuating water inflow, they can only adjust by throttling, further aggravating hydraulic losses and resulting in poor adaptability.

[0006] Secondly, the impeller has only a single centrifugal structure without auxiliary blades or pressure relief holes for force balance. During operation, the axial and radial hydraulic loads are concentrated, and the bearings are prone to wear and failure due to long-term alternating loads. The single mechanical seal structure has weak resistance to silt erosion and a high rate of leakage failure. Its structural design without shutdown flushing easily leads to silt accumulation and impeller jamming. After shutdown in water with high solids content, silt sedimentation can easily seize the pump body, resulting in a large workload for maintenance and disassembly. The explosion-proof supporting structure is conservative, and the explosion-proof reliability is insufficient under complex vibration and silt conditions.

[0007] Therefore, there is a clear practical necessity to design a permanent magnet explosion-proof submersible electric pump for mining that can improve the reliability and safety of complex downhole environments and reduce clogging and wear. Summary of the Invention

[0008] To solve one of the aforementioned technical problems, the present invention adopts the following technical solution: a permanent magnet explosion-proof submersible electric pump for mining, comprising an explosion-proof housing assembly, a cable inlet sealing assembly, a double-end bearing support assembly, a permanent magnet drive unit, and a hydraulic pumping assembly; the double-end bearing support assembly is fixedly installed in the mounting cavity of the explosion-proof housing assembly, and the permanent magnet drive unit is fitted inside the double-end bearing support assembly; the exterior of the permanent magnet drive unit is connected to the double-end bearing support assembly, and the lower end of the permanent magnet drive unit extends into the mounting cavity below the double-end bearing support assembly and is coaxially connected to the hydraulic pumping assembly; a base with liquid inlet channels on both sides is fixedly installed at the bottom of the explosion-proof housing assembly; the opening of the hydraulic pumping assembly faces downward and communicates with the external space; the outlet of the hydraulic pumping assembly is connected to the cooling channel of the cavity surrounding the permanent magnet drive unit, and the water in the cooling channel is discharged through the drainage channel on the top left side.

[0009] Preferably, the explosion-proof housing assembly includes a housing that is vertically and coaxially fixed to the periphery of the double-end bearing support assembly. The bottom of the housing is fixed relative to the base. A connecting plate is coaxially fixed to the bottom opening of the housing. The lower output end of the permanent magnet drive unit moves and seals through the central hole of the connecting plate and extends below it to be fixed to the hydraulic pump assembly. A cable outlet box with a sealing cover is fixed to the upper part of the mounting cavity inside the housing and is located above the double-end bearing support assembly. The upper neck end of the cable outlet box moves and seals through to the top cover of the housing. The cable inlet sealing assembly is installed in the cable outlet box. The outer end of the cable inlet sealing assembly is connected to an external power supply. The inner end of the cable inlet sealing assembly extends into the cable outlet box and is electrically connected to the permanent magnet drive unit.

[0010] Preferably, the cable inlet sealing assembly includes a mining cable, the outer end of which is used to connect to an external power supply, and the inner end of which extends into the wiring cavity of the outlet box and is electrically connected to the wiring terminal of the permanent magnet drive unit through a wiring plate.

[0011] Preferably, a pressure sleeve is fixedly sleeved on the outer wall of the mining cable near the neck end of the outlet box. The pressure sleeve is fastened to the mining cable by a cross-groove pan head screw. The pressure sleeve extends into the threaded cavity of the neck section of the outlet box through its lower outer wall with external threads, and the contact part is sealed by a metal flat washer and a cable rubber sealing ring.

[0012] Preferably, a receiving plate is sealed on the outer wall of the neck section of the outlet box above the outer casing, and a pressure plate is attached to the upper surface of the receiving plate. An O-ring is sandwiched between the receiving plate and the outlet box to form a static explosion-proof seal. The receiving plate provides an installation bearing surface for the cable sealing assembly, disperses the external tension of the cable, and prevents the intrusion of underground water and explosive gas along the inlet gap.

[0013] Preferably, the double-ended bearing support assembly includes an upper bearing housing and a lower bearing housing arranged at relative intervals. Both the upper and lower bearing housings are coaxially fixed relative to the housing. An upper deep groove ball bearing and a lower deep groove ball bearing are respectively installed inside the upper bearing housing and the lower bearing housing. The permanent magnet drive unit is installed between the upper and lower bearing housings. The top and bottom edges of the permanent magnet drive unit are respectively sealed to the upper and lower bearing housings. The lower part of the output end of the permanent magnet drive unit moves and seals through the central hole of the connecting plate and connects to the hydraulic pumping assembly below it.

[0014] Preferably, the permanent magnet drive unit includes a vertically arranged central shaft, with its upper and lower ends movably inserted into corresponding upper and lower deep groove ball bearings, respectively. A permanent magnet synchronous rotor is connected to the periphery of the central shaft via a transmission key. A winding stator core is arranged around the periphery of the permanent magnet synchronous rotor. A protective cooling housing is coaxially arranged around the winding stator core. The edges of the upper and lower ends of the protective cooling housing are fixedly and sealed to the upper bearing seat and the lower bearing seat, respectively.

[0015] The protective cooling housing and the outer shell form the cavity cooling channel.

[0016] Preferably, an oil channel for injecting oil into the inner cooling lubrication cavity of the protective cooling housing is provided on the connecting plate as needed, and an oil plug bolt is detachably sealed at the outer end of the oil channel.

[0017] Preferably, the hydraulic pumping assembly includes an impeller body keyed to the lower end of the central shaft, a pump body disposed below the impeller body, the pump body and the connecting plate cooperating to form a pump chamber, an inlet gap between the periphery of the impeller body and the inner wall of the pump chamber, a suction port on the lower inner side of the impeller body for sucking water, and each discharge port on the side wall for delivering water to the space below the connecting plate;

[0018] The connecting plate has an opening or channel pre-formed on its side wall to connect the water pump chamber with the cooling channel of the clamping cavity.

[0019] Preferably, the inner end of the impeller body is movably and sealed to the outer side wall of the central tube of the connecting disc through an inner and outer sand-throwing ring. The outer end of the impeller body is movably and sealed to the central inlet of the pump body, and the central inlet is connected to the corresponding inlet channel.

[0020] It should also be noted that a grounding sign is installed on the outer wall of the mining cable.

[0021] This invention also provides an assembly process for a permanent magnet explosion-proof submersible electric pump for mining, comprising the following steps: S1, fine pretreatment of parts to provide qualified workpieces for subsequent precision assembly; S2, preheating of the housing and pressing of the stator onto the qualified workpiece to obtain a housing body with a pre-assembled stator; S3, assembly and sealing of the upper support structure of the stator housing body to form an upper rotary support reference; S4, installation of the rotary component based on the upper support reference to complete the rotor pre-assembly; S5, assembly of the lower support structure after rotor positioning to complete the assembly of the entire machine body; S6, gradient airtightness testing after the assembly of the entire machine body to complete the final assembly of the entire machine.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. This invention adopts a 3000–4500r / min permanent magnet synchronous explosion-proof rotor stator structure with synchronous frequency conversion drive. The motor efficiency is 40%–50% higher than that of traditional asynchronous submersible pumps. It has a high power factor and no ineffective excitation loss. It can dynamically adjust the flow rate and head according to the downhole water inflow conditions, and has a wider range of working conditions.

[0024] Meanwhile, this invention is equipped with an original closed permanent magnet drive unit and a self-cooling system with a variable diameter flow channel in the cavity. Relying on the connection structure between the pump cavity and the cooling channel, it realizes heat exchange through the circulation of water from the same source, effectively eliminating the problems of high-temperature demagnetization and energy efficiency decay of the permanent magnet motor. It completely solves the industry pain points of high energy consumption, poor adaptability to working conditions, and high cost of long-term continuous operation of traditional asynchronous pumps, and is perfectly adapted to the 24-hour uninterrupted drainage working conditions of coal mines.

[0025] 2. This invention leverages the high-speed drive characteristics of permanent magnet pumps, significantly reducing the size of the motor core and the overall weight of the pump compared to traditional low-speed asynchronous pumps, while maintaining the same power output. Combined with a compact integrated layout featuring coaxial support at both ends and an externally mounted structure without complex external piping, it effectively solves the problems of traditional mining pumps being bulky, difficult to transport in narrow underground tunnels, and slow deployment in emergency situations. Furthermore, this invention employs a modular power expansion design with the same core diameter but different core lengths, covering a full range of power models from 11kW to 22kW. The high degree of component standardization and platformization simplifies the assembly process, reduces mass production costs, and decreases the need for spare parts and subsequent maintenance costs in underground equipment, significantly improving the convenience of underground emergency relocation and daily maintenance.

[0026] 3. Addressing the shortcomings of traditional water pumps, such as uneven hydraulic stress, impeller clogging, and easy wear and failure of bearings and seals, this invention relies on a double-end bearing support structure to distribute alternating impact stress, thoroughly improving the bearing and seal wear conditions and significantly extending the service life of core transmission and sealing components. Simultaneously, the equipment is equipped with a shutdown anti-clogging flushing function, which can be connected to an external water source to flush and clean coal dust and silt accumulated in the pump chamber and impeller, preventing hard impurities from intruding into the dynamic seal gap. Combined with the self-cleaning and anti-scaling properties of the cooling channel, it avoids multiple blockage and wear failures, making it suitable for harsh water inflow conditions with high impurities and high silt content in coal mines.

[0027] 4. The present invention adopts a triple progressive sealing structure of skeleton oil seal, mechanical seal and air chamber during sealing, which blocks the seepage path of mine water in multiple layers. Compared with the traditional single sealing structure, it greatly reduces the probability of water leakage and sand ingress failure.

[0028] In addition, the entire machine is designed in strict accordance with the GB / T3836-2021 and KA / T671-2005 mining standards, has an Ex db IMb explosion-proof rating, and has passed the 0.2MPa airtightness test, the 1.5 times pressure water pressure test, and high insulation performance control.

[0029] Simultaneously, it is equipped with precise assembly processes such as quantitative thin-layer grease explosion-proof protection, gradient airtightness testing, and step-by-step diagonal locking stress relief to stably maintain the accuracy of the explosion-proof gap and eliminate the hidden dangers of seal failure and explosion-proof deviation in the strong vibration and highly corrosive environment underground. Combined with a full-area water cooling system to ensure the continuous and stable operation of the equipment, it effectively makes up for the shortcomings of traditional explosion-proof water pumps in terms of conservative structure and insufficient reliability under harsh working conditions, and meets the long-term safe operation requirements of explosive gas environments in coal mines. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or components are generally identified by similar reference numerals. In the drawings, the elements or components are not necessarily drawn to scale.

[0031] Figure 1 This is a schematic diagram of the internal cross-sectional structure of the submersible electric pump of the present invention.

[0032] In the diagram: 1. Outer casing; 2. Terminal box; 3. Connector plate; 4. Pressure plate; 5. Mining cable; 6. Terminal plate; 7. Pressure sleeve; 8. Pressure cap; 9. Metal flat washer; 10. Cable rubber seal ring; 11. Upper bearing housing; 12. Lower bearing housing; 13. Base; 14. Pump body; 15. Impeller body; 16. Outer sand-throwing ring; 17. Inner sand-throwing ring; 18. Connecting plate; 19. Oil plug bolt; 20. Oil passage; 21. Upper deep groove ball bearing; 22. Protective cooling housing; 23. Transmission key; 24. Permanent magnet synchronous rotor; 25. Stator core with windings; 26. Lower deep groove ball bearing; 27. Terminal block; 28. Suction port; 29. ​​Drain port; 30. Drainage passage; 31. Inlet passage. Detailed Implementation

[0033] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore merely examples and should not be used to limit the scope of protection of the present invention. Specific solutions of the present invention are as follows: Figure 1 As shown in the image.

[0034] Example 1: A permanent magnet explosion-proof submersible electric pump for mining includes an explosion-proof housing assembly, a cable inlet sealing assembly, a double-end bearing support assembly, a permanent magnet drive unit, and a hydraulic pumping assembly. The double-end bearing support assembly is fixedly installed in the mounting cavity of the explosion-proof housing assembly. The permanent magnet drive unit is fitted inside the double-end bearing support assembly. The exterior of the permanent magnet drive unit is connected to the double-end bearing support assembly. The lower end of the permanent magnet drive unit extends into the mounting cavity below the double-end bearing support assembly and is coaxially connected to the hydraulic pumping assembly. A base 13 with liquid inlet channels 31 on both sides is fixedly installed at the bottom of the explosion-proof housing assembly. The opening of the hydraulic pumping assembly faces downwards and communicates with the external space. The outlet of the hydraulic pumping assembly is connected to a cooling channel in the cavity surrounding the permanent magnet drive unit. The water in the cooling channel is discharged through a drainage channel 30 on its top left side.

[0035] The equipment adopts an integrated explosion-proof cavity structure. The dual-end bearing support assembly realizes the coaxial positioning support of the permanent magnet drive unit, which completely solves the problems of shaft eccentricity and running vibration caused by the impact of high-pressure water and water flow disturbance in the well.

[0036] The equipment adopts a bottom water inlet, side flow guidance, outer ring cooling, and top drainage method. The hydraulic pumping assembly directly extracts the water accumulated in the well, coupling the pumping operation with the equipment's self-cooling function. During operation, the water accumulated in the well enters the hydraulic pumping assembly through the liquid inlet channels 31 on both sides of the base 13. After being pressurized and guided by the impeller, it is precisely transported to the cavity cooling channel outside the permanent magnet drive unit. The fluidity of the pumping medium itself carries away the heat generated by the continuous operation of the permanent magnet drive unit, such as eddy current loss, copper loss, and magnetic loss. Finally, the water after heat exchange is discharged from the top left drainage channel 30, forming a closed-loop self-cooling circulation system.

[0037] This structure uses the pumping medium as a cooling medium simultaneously, eliminating the need for additional auxiliary heat dissipation components such as cooling fans, cooling pipes, and cooling water tanks. It is better suited to the requirements of confined spaces in coal mines, prohibition of exposed non-explosion-proof electrical equipment, and maintenance-free long-term operation of equipment. At the same time, the fully enclosed cavity structure can completely isolate the internal electrical structure from contact with explosive gases and humid corrosive media underground. Structurally, it meets the explosion-proof safety standards for mining and is suitable for high-risk and special operating conditions such as deep well mining, drainage of water accumulation in roadways, and emergency drainage underground.

[0038] To make the technical solution of the present invention clearer, the present invention will now be further described. The explosion-proof housing assembly includes a housing 1 that is vertically arranged and coaxially fixed to the periphery of the double-end bearing support assembly. The bottom of the housing 1 is fixed relative to the base 13. A connecting plate 18 is coaxially fixed to the bottom opening of the housing 1. The lower output end of the permanent magnet drive unit moves and seals through the central hole of the connecting plate 18 and extends below it to be fixed to the hydraulic pump assembly. A cable outlet box 2 is sealed and fixed to the upper part of the mounting cavity inside the housing 1, and is provided above the double-end bearing support assembly. The upper neck end of the cable outlet box 2 moves and seals through to the top cover of the housing 1. The cable inlet sealing assembly is installed in the cable outlet box 2. The outer end of the cable inlet sealing assembly is connected to the external power supply end, and the inner end of the cable inlet sealing assembly extends into the cable outlet box 2 and is electrically connected to the permanent magnet drive unit.

[0039] Specifically, this solution disassembles the explosion-proof housing assembly into three coaxial, sealed, separate structures: the outer shell 1, the bottom connecting plate 18, and the upper outlet box 2, forming a layered assembly, layered sealing, and layered explosion-proof protective structure. During overall assembly, the outer shell 1 encloses the internal double-end bearing support assembly and permanent magnet drive unit to form the main explosion-proof housing cavity. The bottom is sealed and isolated from the hydraulic pump assembly below through the connecting plate 18. A dynamic seal is set at the position where the central shaft passes through the central hole of the connecting plate 18 to prevent corrosive water containing mud and sand from entering the electrical area inside the housing. The upper part of the outer shell 1 has a reserved installation cavity for installing the outlet box 2. The outlet box 2 is independently sealed and located above the support structure. The cable only passes through the top cover of the outer shell 1 from the neck of the outlet box 2, completely isolating the electrical wiring area from the underground water and mud. During the operation of the entire structure, the outer shell 1, the connecting plate 18, and the outlet box 2 each independently form an explosion-proof joint surface, and the explosion-proof gap is controlled in sections. Even if a slight loss occurs in the seal at a certain point, the explosion-proof performance of the other sections of the explosion-proof structure can still be maintained. At the same time, the split layout can realize the disassembly and maintenance of different areas. If the hydraulic components below need to be repaired, only the connecting plate 18 needs to be removed. If the internal drive components need to be repaired, the upper outlet box 2 can be removed separately, which greatly reduces the maintenance time in the confined space downhole.

[0040] To make the technical solution of the present invention clearer, the present invention will now be further described. The cable inlet sealing assembly includes a mining cable 5. The outer end of the mining cable 5 is used to connect to an external power supply terminal. The inner end of the mining cable 5 extends into the wiring cavity of the outlet box 2 and is electrically connected to the wiring terminal of the permanent magnet drive unit through the wiring plate 27.

[0041] Throughout the entire operation, the independently enclosed wiring cavity of the junction box 2 physically isolates the electrical connection area from the external water and gas environment. The mining cable 5 itself possesses the basic characteristics of being flame-retardant, tear-resistant, corrosion-resistant, and waterproof, and together with the terminal block 27, it achieves stable crimping and fixing of multiple cables, completely isolating the electrical connection points from external corrosive media and explosive gases. The entire wiring and power supply structure is completely isolated from the main cooling channel of the water pump and the hydraulic pumping area, and will not be directly washed by the circulating cooling water flow or underground mud and sand. The independent and sealed space of the wiring cavity can reduce the splashing of cooling media and the accumulation of impurities on the surface of the terminal blocks.

[0042] To make the technical solution of the present invention clearer, the present invention will now be further described. A pressure sleeve 7 is fixedly sleeved on the outer wall of the mining cable 5 near the neck end of the outlet box 2. The pressure sleeve 7 is fastened to the mining cable 5 by a cross-groove pan head screw. The pressure sleeve 7 extends into the threaded cavity of the neck section of the outlet box 2 by screwing its lower outer wall with external threads. The contact part is sealed by a metal flat washer 9 and a cable rubber sealing ring 10.

[0043] When this structure is in operation, the pressure sleeve 7 is pre-fitted onto the outer wall of the mining cable 5 and radially locked using a cross-groove pan head screw, so that the pressure sleeve 7 and the cable sheath fit tightly together, first achieving a fixed constraint without relative sliding between the pressure sleeve 7 and the cable; then the lower end of the external thread of the pressure sleeve 7 is screwed into the threaded cavity of the neck of the outlet box 2. During the tightening process, the pressure sleeve 7 axially compresses the metal flat washer 9 and the cable rubber sealing ring 10, and the multi-layer sealing components simultaneously fill the micro-fit gap between the pressure sleeve 7, the outlet box 2, and the cable.

[0044] To make the technical solution of the present invention clearer, the present invention will now be further described. A receiving plate 3 with a top sleeve and a pressure cap 8 is sealed on the outer wall of the neck section of the outlet box 2 above the outer shell 1. A pressure plate 4 is attached to the upper surface of the receiving plate 3. An O-ring is sandwiched between the receiving plate 3 and the outlet box 2 to form a static explosion-proof seal. The receiving plate 3 provides an installation bearing surface for the cable sealing assembly and disperses the external tension of the cable, while preventing the intrusion of underground water and explosive gas along the inlet gap.

[0045] It should be noted that the junction box 3 is fully sealed on the outer wall of the neck of the outlet box 2. An O-ring is sandwiched between the mating surfaces of the two to form an annular static sealing layer, which pre-isolates external water and gas media from penetrating into the shell. The top of the junction box 3 has a built-in sleeve structure that matches the pressure cover 8, and the upper surface is attached to the pressure plate 4. The pressure plate 4 and the junction box 3 together form a complete load-bearing platform. The entire cable sealing assembly is fully assembled above the junction box 3. All the downward and lateral tension generated by the cable is borne by the rigid junction box 3 and transferred to the main body of the outer shell 1. The concentrated load will not be applied to the thin-walled neck of the outlet box 2, reducing the deformation and cracking of the outlet box 2.

[0046] The O-ring seal fills the annular assembly gap between the outlet box 2 and the receiving plate 3. The annular complete flexible sealing strip blocks the medium penetration channel, forming a second explosion-proof protection independent of the cable locking structure. Even if there is slight leakage at the cable end seal, the static seal between the receiving plate 3 and the outlet box 2 can still prevent dangerous media from entering the main cavity of the equipment, achieving double-layer medium barrier protection.

[0047] To make the technical solution of the present invention clearer, the present invention will now be further described. The double-end bearing support assembly includes an upper bearing seat 11 and a lower bearing seat 12 arranged at relative intervals. The upper bearing seat 11 and the lower bearing seat 12 are both coaxially fixed relative to the outer shell 1. An upper deep groove ball bearing 21 and a lower deep groove ball bearing 26 are respectively installed inside the upper bearing seat 11 and the lower bearing seat 12. The permanent magnet drive unit is installed between the upper bearing seat 11 and the lower bearing seat 12. The top and bottom edges of the permanent magnet drive unit are respectively sealed to the upper bearing seat 11 and the lower bearing seat 12. The lower part of the output end of the permanent magnet drive unit moves and seals through the central hole of the connecting plate 18 and is connected to the hydraulic pumping assembly below it.

[0048] As can be seen, this scheme adopts an upper bearing seat 11 and a lower bearing seat 12 arranged separately to form a double-support coaxial support. The two are simultaneously fixed inside the outer shell 1 to ensure the overall coaxial reference. The upper deep groove ball bearing 21 and the lower deep groove ball bearing 26 form bidirectional constraints from the upper and lower ends of the rotating shaft, respectively. The permanent magnet drive unit is clamped and installed in the middle of the two sets of bearing seats. The upper and lower edges are respectively sealed and connected to the corresponding bearing seats, thus isolating the permanent magnet drive unit as a whole to form an independent sealed space. The bottom rotating shaft passes through the connecting plate 18 and connects to the hydraulic pump assembly.

[0049] During operation, the radial silt impact load generated by the lower hydraulic pump assembly is shared by the upper and lower sets of bearings. The axial upward thrust from the high-pressure water in the well is borne by the lower bearing. The axial reverse tension generated by the equipment start-up and shutdown and water flow impact is limited by the upper bearing. The bidirectional bearings work together to offset all alternating loads. The upper and lower end faces of the permanent magnet drive unit are sealed to the bearing housing, preventing impurity-containing mineral water in the outer cavity cooling channel from invading the internal rotor and stator areas, reducing silt accumulation and wear on the bearings and iron core. At the same time, the dual-support coaxial constraint can stably maintain a uniform air gap between the stator and rotor. Even under long-term alternating impact, there will be no eccentric rubbing. It is suitable for high-risk drainage conditions with high impurities, high pressure, and continuous operation in the well.

[0050] To make the technical solution of the present invention clearer, the present invention will now be further described. The permanent magnet drive unit includes a vertically arranged central shaft. The upper and lower ends of the central shaft are respectively movably inserted into the corresponding upper deep groove ball bearing 21 and lower deep groove ball bearing 26. A permanent magnet synchronous rotor 24 is connected to the periphery of the central shaft through a transmission key 23. A stator core 25 with windings is arranged around the periphery of the permanent magnet synchronous rotor 24. A protective cooling housing 22 is coaxially arranged around the periphery of the stator core 25 with windings. The edges of the upper and lower ends of the protective cooling housing 22 are fixedly and sealedly connected to the upper bearing seat 11 and the lower bearing seat 12, respectively. The protective cooling housing 22 and the outer shell 1 form the cavity cooling channel.

[0051] To further explain, this scheme uses the central shaft as the core of rotational bearing. The upper and lower ends of the central shaft are supported by the upper deep groove ball bearing 21 and the lower deep groove ball bearing 26 respectively. The torque is synchronously transmitted between the central shaft and the permanent magnet synchronous rotor 24 by the transmission key 23, ensuring stable output of rotational power. The permanent magnet synchronous rotor 24 is coaxially fitted with a stator core 25 with windings. The entire stator and rotor assembly is completely wrapped by the outer protective cooling housing 22. The upper and lower edges of the protective cooling housing 22 are sealed and fixed to the upper bearing seat 11 and the lower bearing seat 12 respectively, forming a completely closed independent oil-immersed inner cavity to isolate the external fluid medium.

[0052] An annular space is reserved between the outer wall of the protective cooling housing 22 and the inner wall of the outer shell 1 to form a jacketed cooling channel. The ore water delivered by the hydraulic pump assembly continuously circulates inside the jacketed cooling channel. The water flows completely along the outer wall of the protective cooling housing 22, continuously carrying away the heat generated by the internal stator and rotor through heat conduction in the metal shell. During the operation of the entire structure, the ore water containing impurities only flows in the external jacketed cooling channel and will not enter the contact windings and permanent magnets inside the protective cooling housing 22. The internal lubrication, temperature uniformity and insulation protection are achieved by insulating cooling oil, while the external cooling relies on continuous heat exchange and cooling by circulating ore water. At the same time, the sealed shell prevents the internal electric arc from spreading outward, simultaneously addressing the three essential downhole requirements of explosion protection, mud and sand abrasion prevention and efficient continuous heat dissipation.

[0053] In addition, it should be noted that a further preferred embodiment is provided here: the jacketed cooling channel is configured as an annular variable diameter flow channel that runs vertically through the shaft, with an overall annular gap width of 3mm-8mm. It adopts a gradually changing structural design that is narrower at the top and wider at the bottom. The maximum gap at the bottom connection to the hydraulic pump assembly is 8mm, and the minimum gap at the top drain end is 3mm. This variable diameter structure can create a progressive pressurized turbulent flow effect when the cooling water flows from bottom to top, which greatly improves the heat exchange efficiency of the water flow and the outer wall of the casing.

[0054] The substrate (inner wall of outer shell 1 and outer wall of machine casing) at the inner and outer walls of the cooling channel of the cavity is uniformly arrayed with hemispherical micro-bump structures. The spherical radius of the micro-bumps is set to 1.5mm, and the center distance between adjacent micro-bumps is 4mm. The micro-bumps do not change the overall assembly size and external drawing structure, but only form turbulence inside the flow channel. When the water flows through, it continuously cuts the water flow boundary and destroys the static boundary layer of the water flow, which is used to greatly improve the convective heat transfer effect.

[0055] The inner wall of the flow channel and the outer surface of the micro-protrusions are uniformly sprayed with a superhydrophobic coating with a thickness of 0.05mm-0.1mm. Relying on the micro-concave-convex structure, a biomimetic lotus leaf effect is formed, which can effectively enhance the coating adhesion performance and reduce the coating failure caused by long-term high-speed water flow. It can also effectively reduce the probability of coal powder, silt, calcium and magnesium ion impurities adhering and scaling in coal mine water, keep the flow channel unobstructed and the heat exchange surface clean for a long time, and reduce heat dissipation failure and poor drainage caused by flow channel scaling and diameter reduction.

[0056] In addition, the micro-bumps, combined with the superhydrophobic coating, form a micro-gap air film barrier, which effectively reduces the direct hard thermal shock between the low-temperature mine water and the high-temperature casing wall, improving structural stability. At the same time, the array of micro-bumps buffers the impact vibration of the water flow under the conditions of water flow fluctuation and pump start-stop, reducing the resonance noise of the whole machine operation, and also has the auxiliary effect of noise reduction and vibration reduction. Furthermore, the annular variable diameter flow channel can use the water flow pressure difference to form a micro-circulation from top to bottom, reducing the stagnation of dead water in the flow channel, the deposition of impurities, mold growth and microbial growth, and can better adapt to the long-term continuous operation requirements of coal mines with high impurities and high humidity.

[0057] Specifically, underground coal mine water is constantly mixed with a large amount of suspended coal dust, rock dust particles, calcium and magnesium hard scale ions, and sulfide corrosive media, resulting in a much higher impurity content than ordinary sewage. Furthermore, mine drainage systems are strictly prohibited from being shut down arbitrarily, requiring equipment to operate continuously for extended periods, leaving no opportunity for manual shutdown for scale removal and channel cleaning. Simultaneously, the underground water remains at a consistently low temperature, while the continuous operation of the drive unit generates a significant temperature rise, leading to drastic temperature fluctuations. This optimized solution employs a gradually narrowing, bottom-widening channel structure. As the water flows upwards, the flow cross-section gradually contracts, and the water velocity and fluid pressure progressively increase, naturally creating continuous and stable turbulent disturbances. This allows the water to scour the channel walls at high speed throughout the entire flow, suppressing the sedimentation and accumulation of large particles from a fluid dynamics perspective.

[0058] Simultaneously, the precisely sized hemispherical micro-protrusions arrayed on the channel wall actively cut the boundary layer of the water flow, continuously disturbing the fluid medium and weakening microscopic stagnant water areas. Combined with a fully covered superhydrophobic coating, the channel wall possesses extremely strong anti-adhesion and anti-scaling properties, preventing coal dust, silt, and mineral ions from adhering and accumulating. Furthermore, the micro-protrusions and the superhydrophobic coating work together to form a microscopic air film isolation layer, isolating the low-temperature mine water from the high-temperature shell's rigid thermal shock and avoiding the fatigue caused by alternating hot and cold stresses in the metal shell. At the same time, the micro-circulation formed by the pressure difference in the variable-diameter channel can continuously flush away dead corners, reducing the deposition and mold growth of microorganisms and sludge.

[0059] To make the technical solution of the present invention clearer, the present invention will now be further described. An oil channel 20 for injecting oil into the inner cooling lubrication cavity of the protective cooling housing 22 is provided on the connecting plate 18 as needed. An oil plug bolt 19 is detachably sealed at the outer end of the oil channel 20.

[0060] Furthermore, after an appropriate amount of insulating cooling oil is introduced into the internal cooling lubrication cavity, it is used to lubricate each bearing, wet the interior of the permanent magnet drive unit, and complete internal cooling. At the same time, the pressure equalization characteristics of the sealed oil medium ensure that the permanent magnet rotor and stator core are in an isobaric oil immersion environment throughout the process, offsetting the pressure difference between the underground diving water pressure and the internal temperature rise pressure, and weakening the infiltration of high-pressure water into the internal cavity. The oil can fill the air gap between the stator and rotor and the fine gaps in the windings, eliminating the risk of air ionization, significantly improving the explosion-proof insulation performance in mining applications, and reducing partial discharge breakdown faults in humid environments. At the same time, the oil has damping and buffering characteristics, which can absorb the radial and axial micro-runouts of the rotor at high speed, correct the rotor rotation coaxiality, reduce bearing wear loss, and suppress electromagnetic vibration and noise. Moreover, the oil can form a dense protective oil film on the surface of the stator windings and permanent magnets, isolating oxygen, water vapor, and sulfide mineral corrosive media, preventing oxidation and demagnetization of permanent magnets and corrosion and aging of winding copper wires, effectively extending the service life of the core components of the motor.

[0061] To make the technical solution of the present invention clearer, the present invention will now be further described. The hydraulic pumping assembly includes an impeller body 15 keyed to the lower end of the central shaft. A pump body 14 is disposed below the impeller body 15. The pump body 14 and the connecting plate 18 cooperate to form a pump chamber. There is a water inlet gap between the periphery of the impeller body 15 and the inner wall of the pump chamber. The liquid suction port 28 on the lower inner side of the impeller body 15 is used for water suction, and the liquid discharge ports 29 on the side wall are used for water delivery to the space below the connecting plate 18.

[0062] The connecting plate 18 has an opening or channel pre-formed on its side wall to connect the water pump chamber with the cooling channel of the clamping cavity.

[0063] The purpose of this step is to drive the impeller body 15 to rotate at high speed via a key drive at the lower end of the central shaft. The drive key 23 ensures stable torque transmission without slippage. The lower suction port 28 of the impeller body 15 draws in water at a low position, and the negative pressure is used to pump the water accumulated in the well. The water flows into the pump chamber through the water inlet gap on the circumference of the impeller. After being pressurized by the impeller, it is radially thrown out from the side wall discharge port 29 and collects in the cavity space below the connecting plate 18. Through the opening on the side wall of the connecting plate 18, the pressurized high-pressure water flow is directly introduced into the cooling channel of the clamping cavity, realizing the integration of the pumping water flow and the cooling water flow from the same source, without the need for additional independent water supply and heat dissipation equipment.

[0064] The system integrates downhole water extraction, pressure boosting, and cooling medium supply. It utilizes the pumping flow as the sole cooling medium flow for the equipment, enabling the pumping operation and the self-cooling system to start and stop synchronously. The water flow is pressurized throughout the cooling channel, and the pumping pressure overcomes the sedimentation resistance of impurities.

[0065] To make the technical solution of the present invention clearer, the present invention will now be further described. The inner end of the impeller body 15 is movably and sealed to the outer side wall of the central tube of the connecting disc 18 through the inner sand-throwing ring and the outer sand-throwing ring 16. The outer end of the impeller body 15 is movably and sealed to the central liquid inlet of the pump body 14, and the central liquid inlet is connected to the corresponding liquid inlet channel 31.

[0066] It should be noted that during the operation of this structure, the impeller body 15 rotates synchronously at high speed with the central shaft. The inner and outer sand-throwing rings 16, nested at the inner end, rotate at high speed along with the impeller as a whole, forming a double-layer rotating centrifugal protective barrier. Mixed water and hard particles near the gap are quickly thrown outward under the action of centrifugal force, preventing them from approaching the mating gap between the central tube and the impeller. The inner and outer sand-throwing rings 16 can be directly installed by matching their sizes and moving as needed. Both can use sand-throwing rings commonly used in the prior art. For example, the sand-throwing ring structure disclosed in the existing patent literature (patent title: A Sand-throwing Ring for a Mining Explosion-proof Submersible Sand-draining Pump Motor) can be selected, or other existing sand-throwing rings can be selected as needed, which will not be elaborated here.

[0067] It should also be noted that a grounding sign 6 is installed on the outer wall of the mining cable 5.

[0068] Example 2: Compared with Example 1, this example also includes the following technical features:

[0069] An assembly process for a permanent magnet explosion-proof submersible electric pump for mining includes the following steps: S1, Refined pretreatment of parts: All parts to be assembled are uniformly deburred, rusted, and degreased, and the explosion-proof surfaces are fully protected to reduce the probability of bumps and scratches; the permanent magnet drive unit is kept at a constant temperature and isolated to prevent demagnetization due to assembly disturbances, and all seals are individually inspected for elasticity and appearance integrity, and defective parts are screened out to provide a qualified base material for subsequent precision assembly;

[0070] S2. Preheating and pressing of the stator based on qualified substrate: After completing the pretreatment of the parts, the protective cooling housing 22 is uniformly preheated at low temperature. The winding stator core 25 is pressed and fixed by a vertical uniform speed and steady pressure pressing method. The heat fitting process is used to achieve non-damaging and high-precision interference fit, ensuring the coaxiality and insulation integrity of the stator, and obtaining the housing body with pre-assembled stator.

[0071] Specifically, this process first relies on pre-treatment of the substrate to ensure that all mating surfaces are free of burrs, rust, and stress defects, providing a benchmark for high-precision assembly. Next, the protective cooling housing 22 undergoes uniform low-temperature preheating, causing uniform, slight thermal expansion of the housing's inner bore to eliminate local dimensional deviations and avoid the hard extrusion scratches caused by forced pressing at room temperature. Subsequently, a vertical, uniform, and stable pressing method is used to center and press-fit the stator core 25 with windings from top to bottom. The entire process is free from impact, off-center load, and local stress concentration, relying on the subsequent natural cooling and contraction of the housing to form a uniform, fully fitted, high-precision interference fit. The entire assembly process replaces rigid forced assembly with flexible, heat-deformation assembly, protecting the winding insulation layer from scratches, preventing stator core lamination displacement, and ensuring the coaxial benchmark of the entire machine remains unchanged.

[0072] This solution employs uniform low-temperature preheating of the entire machine and vertical, stable, slow-speed pressing. The casing expands and contracts uniformly throughout its entirety, ensuring a perfectly round and tightly fitted stator core without any gaps or residual local stress. This ensures that the core remains stable and the casing exhibits no micro-deformation during long-term continuous operation. Furthermore, this solution utilizes pre-reserved gaps in the hot fitting process and flexible, uniform-speed, stable-pressure pressing, eliminating any hard extrusion or edge scraping. This preserves the integrity of the stator insulation varnish film, prevents microscopic insulation defects, and significantly improves the insulation lifespan of the windings under damp and corrosive conditions in mines. This solution provides non-destructive assembly and protection for insulation in damp and explosion-proof mine environments.

[0073] It should also be explained that this process ensures the ultra-high roundness and coaxiality of the stator inner circle through precise hot-fitting and pressure-stabilizing assembly, pre-locks the uniform air gap between the stator and rotor, eliminates the problem of uneven magnetic pull, avoids the risk of vibration fatigue and permanent magnet demagnetization under long-term start-stop and load fluctuations in the well, and at the same time significantly reduces bearing wear and noise resonance problems.

[0074] S3. Sealing assembly of the upper support structure based on the stator housing body: After the stator and housing are assembled, a thin layer of protective grease is evenly and quantitatively applied to the explosion-proof mating surface of the upper bearing seat 11 and the protective cooling housing 22 to reduce the alignment friction resistance. The upper bearing seat 11 is precisely aligned and sealed to form a rotation support reference in the upper part.

[0075] This process involves assembly work based on the pre-assembled stator housing. First, a thin layer of protective grease is evenly and quantitatively applied to the explosion-proof mating surfaces of the upper and lower joints. The grease can lubricate and reduce resistance during assembly, reducing the probability of scratching the precision explosion-proof metal surfaces during hard alignment. At the same time, after the grease cures, it will form a sealed protective oil film on the joint surface, preventing corrosive media from seeping into the gaps. Before assembly, the upper bearing seat 11 and the protective cooling housing 22 are placed in the same constant temperature environment to achieve isothermal treatment, eliminating dimensional deviations caused by temperature differences between the two workpieces. Then, a coaxial precise alignment method is used to slowly fit and assemble them, preventing damage to the explosion-proof surfaces caused by tilting or unilateral extrusion. After assembly, sealing and fixing are completed. The upper bearing seat 11 is used to construct the upper rotation support benchmark of the whole machine, providing upper limit support for the subsequent permanent magnet synchronous rotor 24.

[0076] Specifically, this process involves isothermal coaxial precision alignment and assembly. The coaxiality of the upper bearing housing 11 is corrected using the inner circle of the stator of the protective cooling housing 22 as a unified reference. The upper and lower bearing housings 12 form a completely symmetrical bidirectional support reference. The air gap between the stator and rotor is uniform throughout, which significantly reduces electromagnetic vibration caused by load fluctuations and water flow impacts in the mine, and reduces the probability of irreversible demagnetization of the permanent magnet at high temperatures. This provides a coaxial reference locking effect specifically for permanent magnet explosion-proof water pumps. In addition, a thin layer of protective grease fills the microscopic capillary gaps of the stop, forming a continuous isolation oil film that blocks the penetration channels of water vapor and corrosive ions, significantly slows down the corrosion rate of the explosion-proof surface, extends the effective service life of the explosion-proof machine, and reduces the number of frequent disassembly and maintenance in the confined space underground, thus taking into account both explosion-proof safety and the continuous drainage production needs of the mine.

[0077] S4. Install the rotating component based on the upper support reference: Relying on the central through hole reserved in the upper support structure, the permanent magnet synchronous rotor 24 is vertically installed into the stator inner hole from top to bottom to ensure uniform circumferential air gap. The upper end of the rotating component is temporarily supported inside the upper bearing seat 11 to reduce installation bumps and complete the pre-installation of the rotating component.

[0078] As can be seen, in this process, the upper bearing housing 11 assembled in the previous step is used as a fixed rotation support reference. The central through hole forms a vertical guide channel. The rotor is kept vertical and slowly fed into the stator inner hole from top to bottom. The rotor radial offset is constrained by the through hole limit throughout the process. After being lowered into place, the upper end of the rotor is directly and temporarily supported inside the upper bearing housing 11, forming a single-point support limit in advance. This counteracts the lateral magnetic attraction between the permanent magnet and the stator, reducing the probability of the rotor bumping and scratching against the inner wall of the stator on one side. The whole process is manually controllable and there is no hard contact damage. After the pre-assembly is completed, the rotor naturally maintains a uniform circumferential air gap state, providing a precise coaxial reference for the subsequent assembly of the lower bearing housing 12 and the sealing and shaping of the whole machine. By using the vertical guide through the upper through hole and the temporary support at the upper end to complete the centering and positioning in advance, qualified pre-assembly can be completed in one go, avoiding the production losses caused by assembly errors that cannot be repaired and the scrapping of the whole machine. At the same time, it reduces the probability of chain failures such as electromagnetic high temperature, permanent magnet demagnetization, and single-sided bearing wear caused by rotor eccentric operation, and can better adapt to the harsh working conditions of long-term continuous maintenance-free operation in the well.

[0079] S5. After the rotating component is positioned, assemble the lower support structure: After the permanent magnet synchronous rotor 24 is in place without interference, apply an equal amount of thin protective grease to the mating surface of the lower bearing seat 12 and the lower end stop of the housing, accurately fit and assemble the lower bearing seat 12 and seal it. The upper bearing seat 11 and the lower bearing seat 12 support together clamp and position the permanent magnet synchronous rotor 24. Then, assemble the terminal block 27, the outlet box 2 and the cable inlet sealing assembly in sequence to complete the main assembly of the machine.

[0080] It is important to understand that, under the premise that the permanent magnet synchronous rotor 24 is pre-assembled in the center without any scraping or interference, a thin layer of protective grease is first evenly applied to the mating surface of the lower bearing housing 12 and the explosion-proof stop at the lower end of the protective cooling housing 22. The grease only serves to lubricate the assembly and isolate corrosive media, and will not fill the explosion-proof gap or affect the explosion-proof accuracy. Subsequently, the lower bearing housing 12 is precisely fitted and sealed, forming a rigid clamping structure with the pre-assembled upper bearing housing 11, which locks the permanent magnet synchronous rotor 24 completely in the center coaxial position, completely eliminating the risk of rotor axial movement and radial eccentricity. After the rotor is clamped and positioned, the terminal block 27, the outlet box 2, and the complete set of cable inlet sealing components are assembled in sequence, and the electrical wiring structure is arranged in layers from top to bottom, so that the electrical connection area is independently isolated above the cooling circulating water, reducing the probability of mine water and silt directly scouring the wiring points. The upper and lower bearing seats 12 of this design form a symmetrical rigid clamping structure, and the upper and lower ends of the rotor are synchronously limited, which cancels the axial water pressure thrust and radial water flow impact load in both directions. After assembly, the rotation center is permanently fixed, and the circumferential air gap is uniform throughout, which greatly reduces the probability of eccentric vibration, magnet demagnetization, and explosion-proof surface wear chain failure.

[0081] S6. After the main assembly is completed, a gradient airtightness test is carried out. After the airtightness test is qualified, lubricating medium is added to the bearing position. Finally, a step-by-step diagonal uniform locking process is used to lock all fasteners to prevent loosening, gradually eliminate assembly stress, and complete the final assembly of the whole machine.

[0082] After the main structure of the machine is fully assembled, this process first implements a gradient airtightness test, gradually increasing and maintaining pressure from low to high pressure, and observing whether there are any micro-leakages in each sealed cavity and explosion-proof joint surface. This fully simulates the diving pressure environment at different mining depths. Only when the gradient airtightness is fully qualified can the sealing and isolation structure of the whole machine be judged to meet the standards. After the airtightness test is completed, pure lubricating medium is added to the inside of the bearing to avoid the problem of assembly impurities and grease contamination of the explosion-proof surface throughout the process. Finally, a step-by-step diagonal uniform locking method is adopted to tighten all fasteners diagonally alternately in multiple rounds, slowly releasing the local compressive stress generated by assembly, so that each sealing surface and explosion-proof stop is evenly fitted under force without local deformation and warping, and finally the whole machine is finalized.

[0083] To make the technical solution of the present invention clearer, the present invention will now be further described. Step S2 relies on the qualified and defect-free parts in step S1 to implement the hot fitting process. The inner hole is slightly expanded by preheating the protective cooling housing 22, which reduces the core extrusion offset and the winding insulation being scratched. After the housing cools and shrinks, a high-precision interference fit is formed to ensure the coaxiality accuracy of the stator.

[0084] Specifically, this process is strictly based on the refined pre-treatment of S1 components. All assembly substrates undergo deburring, rust removal, cutting oil removal, and surface micro-defect detection in advance, eliminating unqualified workpieces with bumps, scratches, and rust, thus avoiding the hidden dangers of impurities and defects scratching the winding insulation during assembly. Then, the protective cooling housing 22 is uniformly preheated at a low temperature, causing a uniform and controllable micro-expansion of the inner diameter of the housing. During the press-fitting of the stator core, a small assembly gap is reserved on the inner and outer mating surfaces, eliminating the problems of rigid extrusion and scratching, and single-sided offset and jamming of the core, thus completely protecting the insulation structure at the end of the winding from damage. After the press-fitting is completed, the housing naturally and uniformly cools and shrinks, synchronously clamping the stator core 25 with winding throughout, forming a high-precision interference fit with consistent clamping at all parts of the circumference, stably locking the coaxial reference of the inner circle of the stator, and providing a unified and reliable positioning reference for the subsequent assembly of the upper and lower bearing seats 12 and the pre-assembly of the rotor.

[0085] To make the technical solution of the present invention clearer, the present invention will now be further described. Steps S3 and S5 both adopt a quantitative thin-layer grease coating process, which can reduce the frictional resistance when the metal of the stop is attached, easily complete the alignment and assembly without impact deformation, fill the micro-processing gaps, provide long-term protection for the explosion-proof joint surface to prevent rust, and ensure the sealing performance of the joint position.

[0086] Furthermore, this solution uniformly implements a quantitative thin-layer grease coating standard in the S3 process of assembling the upper bearing housing 11 and the S5 process of assembling the lower bearing housing 12. By quantitatively controlling the grease coating thickness, a continuous and extremely thin oil film is formed only on the surface of the metal stop, without occupying the explosion-proof mating clearance. During the assembly alignment stage, the thin-layer grease reduces the frictional resistance of the metal stop fitting. During the coaxial fitting of the upper and lower bearing housings 12, there is no hard scraping or unilateral impact, avoiding scratches and deformation damage to the precision explosion-proof surface. After assembly, the oil film fills the micro-uneven gaps generated by machining, isolating downhole water vapor and corrosive ions from direct contact with the metal substrate. The upper and lower explosion-proof stops simultaneously form a long-lasting anti-corrosion protective layer, and the standard clearance of the explosion-proof mating surface is maintained stably throughout the process.

[0087] To make the technical solution of the present invention clearer, the present invention will now be further described. Step S4 utilizes the assembly sequence of first installing the upper support and then installing the rotor. The rotor is vertically hoisted from top to bottom, which can uniformly control the circumferential gap and prevent the permanent magnet and the stator core from attracting and colliding with each other.

[0088] Specifically, this process adopts an assembly method of supporting first and then lowering the rotor. First, the upper bearing seat 11 is assembled and fixed to form a stable upper center guide and support benchmark, and a vertical centering through hole is constructed to enable the rotor to have the conditions for centering and lowering. Then, the permanent magnet synchronous rotor 24 is vertically hoisted and lowered at a uniform speed. Throughout the process, the upper benchmark limits the radial offset and uses vertical gravity to balance the magnetic attraction eccentric torque. The rotor floats in the center and enters the stator inner hole throughout the process, naturally forming a uniform circumferential air gap, effectively avoiding magnetic attraction and wall contact damage.

[0089] This invention employs a complete precision assembly process, including low-temperature hot mounting of the casing, isothermal alignment, upper reference pre-assembly, vertically centered rotor pre-assembly, and step-by-step diagonal stress-relieving locking. This process ensures ultra-high coaxiality and uniform air gap between the stator and rotor in one go, eliminating the problems of eccentric assembly, high vibration, and heavy, difficult-to-disassemble and maintain traditional equipment. The equipment has a compact overall structure, no external cooling pipes, and no exposed or complex joints. Disassembly and assembly only require layer-by-layer disassembly, eliminating the need for overall hoisting, greatly improving the convenience of underground emergency relocation and routine maintenance.

[0090] This invention abandons the traditional open asynchronous motor structure and adopts an independent sealed drive structure that fully encloses the permanent magnet stator and rotor with a protective cooling housing 22. Combined with the sealed clamping of the upper and lower double-end bearing seats, the electrical core is completely isolated from the muddy and sandy mineral water, which greatly improves the heat exchange efficiency compared with the static laminar flow heat dissipation of traditional water pumps.

[0091] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. For those skilled in the art, any alternative improvements or transformations made to the implementation of the present invention fall within the protection scope of the present invention.

[0092] Any aspects of this invention not described in detail are well-known to those skilled in the art.

Claims

1. A permanent magnet explosion-proof submersible electric pump for mining, characterized in that: Including explosion-proof housing assembly, cable inlet sealing assembly, double-end bearing support assembly, permanent magnet drive unit, and hydraulic pumping assembly; A double-end bearing support assembly is fixedly installed in the mounting cavity of the explosion-proof housing assembly. A permanent magnet drive unit is installed inside the double-end bearing support assembly. The exterior of the permanent magnet drive unit is connected to the double-end bearing support assembly. The lower end of the permanent magnet drive unit extends into the mounting cavity below the double-end bearing support assembly and is coaxially connected to the hydraulic pumping assembly. A base with liquid inlet channels on both sides is fixedly installed at the bottom of the explosion-proof housing assembly. The opening of the hydraulic pumping assembly faces downward and communicates with the external space. The outlet of the hydraulic pumping assembly is connected to the cooling channel of the clamp cavity around the permanent magnet drive unit. The water in the cooling channel of the clamp cavity is discharged through the drainage channel on the top left side.

2. The submersible pump according to claim 1, characterized in that: The explosion-proof housing assembly includes a housing that is vertically and coaxially fixed to the periphery of the double-end bearing support assembly. The bottom of the housing is fixed relative to the base. A connecting plate is coaxially fixed to the bottom opening of the housing. The lower output end of the permanent magnet drive unit moves and seals through the central hole of the connecting plate and extends below it to be fixed to the hydraulic pump assembly. A cable outlet box with a sealing cover is fixed to the upper part of the mounting cavity inside the housing and is located above the double-end bearing support assembly. The upper neck end of the cable outlet box moves and seals through to the top cover of the housing. The cable inlet sealing assembly is installed in the cable outlet box. The outer end of the cable inlet sealing assembly is connected to the external power supply end, and the inner end of the cable inlet sealing assembly extends into the cable outlet box and is electrically connected to the permanent magnet drive unit.

3. The submersible electric pump according to claim 2, characterized in that: The cable inlet sealing assembly includes a mining cable. The outer end of the mining cable is used to connect to an external power supply. The inner end of the mining cable extends into the wiring cavity of the outlet box and is electrically connected to the wiring terminal of the permanent magnet drive unit through a wiring plate.

4. The submersible electric pump according to claim 3, characterized in that: The double-end bearing support assembly includes an upper bearing housing and a lower bearing housing arranged at relative intervals. Both the upper and lower bearing housings are coaxially fixed relative to the housing. An upper deep groove ball bearing and a lower deep groove ball bearing are respectively installed inside the upper bearing housing and the lower bearing housing. The permanent magnet drive unit is installed between the upper and lower bearing housings. The top and bottom edges of the permanent magnet drive unit are respectively sealed to the upper and lower bearing housings. The lower part of the output end of the permanent magnet drive unit moves and seals through the central hole of the connecting plate and connects to the hydraulic pumping assembly below it.

5. The submersible electric pump according to claim 4, characterized in that: The permanent magnet drive unit includes a vertically arranged central shaft. The upper and lower ends of the central shaft are respectively movably inserted into the corresponding upper deep groove ball bearing and the lower deep groove ball bearing. A permanent magnet synchronous rotor is connected to the periphery of the central shaft via a transmission key. A stator core with windings is arranged around the periphery of the permanent magnet synchronous rotor. A protective cooling housing is coaxially arranged around the stator core with windings. The edges of the upper and lower ends of the protective cooling housing are fixedly and sealed to the upper bearing seat and the lower bearing seat, respectively. The protective cooling housing and the outer shell form the cavity cooling channel.

6. The submersible pump according to claim 5, characterized in that: An oil channel for injecting oil into the inner cooling lubrication cavity of the protective cooling housing is provided on the connecting plate as needed, and an oil plug bolt is detachably sealed at the outer end of the oil channel.

7. The submersible pump according to claim 6, characterized in that: The hydraulic pumping assembly includes an impeller body keyed to the lower end of the central shaft, a pump body disposed below the impeller body, the pump body and the connecting plate forming a pump chamber, an inlet gap between the periphery of the impeller body and the inner wall of the pump chamber, a suction port on the lower inner side of the impeller body for sucking water, and discharge ports on the side wall for delivering water to the space below the connecting plate; The connecting plate has an opening or channel pre-formed on its side wall to connect the water pump chamber with the cooling channel of the clamping cavity.

8. The submersible pump according to claim 7, characterized in that: A grounding sign is installed on the outer wall of the mining cable.

9. An assembly process for a permanent magnet explosion-proof submersible pump for mining, wherein the submersible pump is the submersible pump as described in claim 1, characterized in that, The assembly process includes the following steps: S1. Refined pre-processing of parts to provide qualified workpieces for subsequent precision assembly; S2. The qualified workpiece completes the preheating of the housing and presses in the stator to obtain the housing body with pre-installed stator; S3. The upper support structure of the stator housing is assembled and sealed to form the upper rotation support reference. S4. Install the rotating components based on the upper support reference to complete the rotor pre-assembly; S5. After the rotor is positioned, assemble the lower support structure to complete the main assembly of the machine. S6. After the main body of the machine is assembled, a gradient airtightness test is carried out to complete the assembly and finalization of the machine.

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