A self-balancing magnetic pump with a shaft core

Abstract

This invention relates to the field of pumps, and more particularly to a magnetic pump with a self-balancing shaft structure. The pump includes a connecting frame, with a pump cover and pump body sequentially fixed to the left end of the connecting frame, and a motor fixed to the right end of the connecting frame. An outer rotating magnet is fixed to the output shaft of the motor, and the outer rotating magnet has a matching inner rotating magnet. A shielding sleeve is provided between the inner and outer rotating magnets. A shaft is fixed to the inner rotating magnet, and bushings are fixed to both ends of the shaft. Bearings and thrust bearings are connected to the bushings, and the thrust bearings are fixed to thrust bearing seats. A connecting shaft is fixed to the left end of the shaft, and an impeller is fixed to the connecting shaft. This invention uses a combination of bushings, bearings, thrust bearings, and thrust bearing seats at both ends of the shaft. The bushings and bearings cooperate as radial supports, thereby ensuring the radial concentricity of the shaft and preventing radial friction. The combination of bearings and thrust bearings ensures axial positioning of the shaft, thereby achieving self-balancing adjustment of the shaft.

Description

Technical Field

[0001] This invention relates to the field of pumps, and more particularly to a magnetic pump with a self-balancing shaft structure. Background Technology

[0002] A magnetic drive pump is a leak-free pump that achieves contactless power transmission through a magnetic drive. It transforms the dynamic seal of a traditional pump into a static seal, thus completely preventing media leakage. Its core principle is: an electric motor drives an outer magnetic rotor to rotate, and the magnetic field penetrates the non-magnetic isolation sleeve, driving the inner magnetic rotor connected to the impeller to rotate synchronously, achieving contactless power transmission. Because the pump shaft and inner magnetic rotor are completely enclosed within the pump chamber, the pumped liquid will not leak out, making it particularly suitable for conveying flammable, explosive, toxic, or highly corrosive media. Patent application number CN201821363991.X discloses a self-cooling magnetic drive pump. During operation, the driving shaft of a magnetic drive pump operates differently from that of a conventional non-magnetic centrifugal pump. Conventional non-magnetic centrifugal pumps have their shafts directly rigidly connected to the motor or connected using a flexible coupling, and are axially fixed to prevent axial movement. The torque at the drive end can be directly transmitted to the drive end shaft, and the speed and torque at the drive end and non-drive end are consistent, resulting in stable shaft operation. The magnetic pump shaft is not directly connected to the drive motor. Instead, it drives the inner magnet to rotate through the magnetic coupling of the outer magnet. The rotational torque and speed of the inner and outer magnets are inconsistent, which is more noticeable during startup and shutdown. The shaft does not perform a single directional rotational motion, but a more complex multi-directional rotational motion with significant axial and radial outward displacement. During operation, the drive shaft of the magnetic pump described in the patent is prone to axial and radial outward displacement. This can lead to problems such as friction between moving and stationary parts, failure of the sealing system, bearing overload, decreased efficiency, and increased vibration during operation. Summary of the Invention

[0003] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention aims to provide a magnetic pump with a self-balancing shaft structure, solving the problems existing in the prior art. This invention combines a shaft sleeve, bearing, thrust bearing, and thrust bearing seat at both ends of the shaft. The shaft sleeve and bearing work together as radial support, ensuring the radial concentricity of the shaft and preventing radial friction. The combination of the bearing and thrust bearing ensures axial positioning of the shaft. When the shaft rotates axially in multiple directions, if it shifts to the left end, the left-end thrust bearing and bearing abut against each other, preventing the shaft from shifting further to the left. Instead, it is deflected to the right by a reaction force. When the shaft shifts to the right end, the right-end thrust bearing and bearing abut against each other, preventing the shaft from shifting further to the right, thus achieving self-balancing adjustment of the shaft.

[0004] (II) Technical Solution

[0005] To achieve the above objectives, the present invention provides the following technical solution: a shaft-driven self-balancing magnetic pump, comprising a connecting frame, a pump cover and a pump body are sequentially fixed to the left end of the connecting frame, a motor is fixed to the right end of the connecting frame, an outer rotating magnet is fixed to the output shaft of the motor, the outer rotating magnet is provided with a matching inner rotating magnet, a shielding sleeve is provided between the inner rotating magnet and the outer rotating magnet, a shaft is fixed to the inner rotating magnet, bushings are fixed to both the left and right ends of the shaft, the bushings are connected to a bearing and a thrust bearing, the thrust bearing is fixed to a thrust bearing seat, a connecting shaft is fixed to the left end of the shaft, and an impeller is fixed to the connecting shaft.

[0006] Preferably, bushing caps are fixed at both ends of the bushing.

[0007] Preferably, the shielding sleeve includes a first annular portion at the left end, a second annular portion fixed to the upper right end of the first annular portion, a first connecting portion fixed to the lower right end of the first annular portion, a second annular portion fixed to the inner end of the first connecting portion, a second connecting portion fixed to the right end of the second annular portion, a third annular portion fixed to the inner end of the second connecting portion, and a cover plate fixed to the right end of the third annular portion.

[0008] Preferably, the outer surface of the first annular portion is in contact with the inner surface of the pump cover, and a first sealing gasket is fixed between the first annular portion and the pump cover. An embedded groove matching the second annular portion is provided at the connection between the pump cover and the connecting frame.

[0009] Preferably, the rightmost bushing cover is locked by a round nut, the right end of the shaft core has a threaded hole that matches the round nut, and a washer and a locking washer are provided between the bushing cover and the round nut.

[0010] Preferably, a first key is fixed on the connecting shaft, a second key is fixed on the shaft core, and a third key is fixed on the output shaft of the motor.

[0011] Preferably, a second sealing gasket is provided between the pump cover and the pump body.

[0012] Preferably, the pump cover has a first through hole and a second through hole, and a filter plate is fixed in the first through hole and the second through hole.

[0013] Preferably, an annular connecting block is fixed between the connecting frame and the motor, a support base is fixed at the bottom of the connecting frame, a cavity is provided inside the support base, and a cooling mechanism is provided inside the support base and the annular connecting block.

[0014] Preferably, the cooling mechanism includes an insulation layer disposed on the inner wall of the cavity, a water tank and a cooling tank disposed on the bottom wall of the insulation layer, the water tank being connected to a water outlet pipe, a water pump being fixed on the water outlet pipe, the outer end of the water outlet pipe being detachably connected to the water inlet of a first cooling pipe, the water outlet of the first cooling pipe extending out of the cooling tank, the cooling tank being filled with ice, the water outlet of the first cooling pipe being detachably connected to a second cooling pipe, the second cooling pipe being disposed within an annular connecting block, the water outlet of the second cooling pipe extending into the water tank.

[0015] (III) Beneficial Effects

[0016] 1. This invention uses a combination of bushings, bearings, thrust bearings, and thrust bearing seats at both ends of the shaft core. The bushings and bearings work together as radial supports to ensure the radial concentricity of the shaft core during operation and prevent radial friction. The combination of bearings and thrust bearings ensures the axial positioning of the shaft core. When the shaft core rotates and moves axially in multiple directions, when the shaft core moves to the left end, the thrust bearing at the left end abuts against the bearing, preventing the shaft core from moving further to the left. Instead, it is offset to the right by the reaction force. When the shaft core moves to the right end, the thrust bearing at the right end abuts against the bearing, preventing the shaft core from moving further to the right, thus achieving self-balancing adjustment of the shaft core.

[0017] 2. The present invention can protect the bushing from wear by setting the bushing cover.

[0018] 3. By configuring the shielding sleeve as consisting of a first annular portion, a second annular portion, a first connecting portion, a second annular portion, a second connecting portion, a third annular portion, and a cover plate, the present invention greatly improves the overall isolation and sealing effect of the shielding sleeve.

[0019] 4. By setting a round nut, washer and locking washer at the right end of the shaft core, the present invention ensures that the round nut will be locked even under high temperature conditions, further ensuring axial self-balancing adjustment.

[0020] 5. This invention enhances the fixing effect between the connecting shaft and the impeller by setting the first key, preventing relative rotation between the two during rotation and ensuring reliable torque transmission; enhances the fixing effect between the shaft core and the inner rotating magnet by setting the second key, preventing relative rotation between the two during rotation and ensuring reliable torque transmission; and enhances the fixing effect between the motor output shaft and the outer rotating magnet by setting the third key, preventing relative rotation between the two during rotation and ensuring reliable torque transmission. Furthermore, the first, second, and third keys also prevent radial displacement of the shaft core.

[0021] 6. By providing a first through hole and a second through hole on the pump cover, the present invention ensures that there is water inside the shielding sleeve. On the one hand, it lubricates the bushing, bearing and thrust bearing and prevents the bushing, bearing and thrust bearing from dry grinding without water. On the other hand, it cools the bushing, bearing and thrust bearing.

[0022] 7. The present invention effectively cools the motor, external rotating magnet, and connecting frame by setting up an annular connecting block, support base, cavity and cooling mechanism, thereby improving the safety of the magnetic pump and extending its service life. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall invention.

[0024] Figure 2 This is a schematic diagram of the shielding sleeve of the present invention.

[0025] Figure 3 For the present invention Figure 1 A schematic diagram with the ring-shaped connecting block and cooling mechanism added.

[0026] Figure 4 This is a schematic diagram of the support base, cavity, and cooling mechanism of the present invention.

[0027] In the diagram: 1-Connecting frame, 2-Pump cover, 3-Pump body, 4-Motor, 5-Outer rotating magnet, 6-Inner rotating magnet, 7-Shielding sleeve, 8-Shaft core, 9-Shaft sleeve, 10-Bearing, 11-Thrust bearing, 12-Thrust bearing seat, 13-Connecting shaft, 14-Impeller, 15-Shaft sleeve cover, 16-First annular part, 17-Second annular part, 18-First connecting part, 19-Second annular part, 20-Second connecting part, 21-Third annular part, 22-Cover plate, 23- 24-Round nut, 25-Washer, 26-Stop washer, 27-First key, 28-Second key, 29-Third key, 30-Second sealing gasket, 31-First through hole, 32-Second through hole, 33-Annular connecting block, 34-Support base, 35-Cavity, 36-Cooling mechanism, 37-Insulation layer, 38-Water tank, 39-Cooling box, 40-Water outlet pipe, 41-Water pump, 42-First cooling pipe, 43-Ice block, 44-Second cooling pipe. Detailed Implementation

[0028] The following will refer to the appendices in the embodiments of the present invention. Figure 1-4 The technical solutions in the embodiments of the present invention have been clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] This invention provides a technical solution: a self-balancing magnetic pump with a shaft core, comprising a connecting frame 1, a pump cover 2 and a pump body 3 fixed sequentially at the left end of the connecting frame 1, a motor 4 fixed at the right end of the connecting frame 1, an outer rotating magnet 5 fixed on the output shaft of the motor 4, an inner rotating magnet 6 matching the outer rotating magnet 5, a shielding sleeve 7 between the inner rotating magnet 6 and the outer rotating magnet 5, a shaft core 8 fixed to the inner rotating magnet 6, bushings 9 fixed at both ends of the shaft core 8, bearings 10 and thrust bearings 11 connected to the bushings 9, the thrust bearings 11 fixed on a thrust bearing seat 12, a connecting shaft 13 fixed at the left end of the shaft core 8, and an impeller 14 fixed on the connecting shaft 13. The connecting frame 1, pump cover 2, and pump body 3 are fixedly connected by bolts, facilitating both connection and disassembly. The connecting frame 1 and motor 4 are also fixed by bolts. The pump body 3 has an inlet and an outlet, and a pump chamber is provided inside the pump body 3. During operation, first connect the inlet of pump body 3 to the inlet pipe, which is connected to the medium to be transported. Connect the outlet to the outlet pipe, which is connected to the destination of the medium. Start motor 4, and its output shaft rotates, driving the outer rotating magnet 5 to rotate, which in turn drives the inner rotating magnet 6 to rotate, which in turn drives the shaft core 8 to rotate, which in turn drives the impeller 14 to rotate, thus realizing the transport of the medium. The shielding sleeve 7 completely isolates the outer rotating magnet 5 and the inner rotating magnet 6 from the transported medium, realizing an integrated sealed structure of motor and pump. This invention uses a combination of bushings 9, bearings 10, thrust bearings 11, and thrust bearing seats 12 at both ends of the shaft core 8. The bushings 9 and bearings 10 cooperate as radial supports, with a clearance of 0.05mm-0.1mm, thus ensuring the radial concentricity of the shaft core 8 during operation and preventing radial friction. The combination of bearings 10 and thrust bearings 11 ensures the axial limit of the shaft core 8, with an axial displacement of 0.5mm on one side and 1mm on both sides. When the shaft core 8 rotates and moves axially in multiple directions, when the shaft core 8 moves to the left end, the thrust bearings 12 and 10 at the left end abut against each other, preventing the shaft core 8 from moving further to the left. Instead, it is offset to the right by the reaction force. When the shaft core 8 moves to the right end, the thrust bearings 11 and 10 at the right end abut against each other, preventing the shaft core 8 from moving further to the right, thus achieving self-balancing adjustment of the shaft core 8.

[0030] Both ends of the bushing 9 are fixed with bushing covers 15. The bushing covers 15 protect the bushing 9 from wear.

[0031] The shielding sleeve 7 includes a first annular portion 16 at its left end, a second annular portion 17 fixed to the upper right end of the first annular portion 16, a first connecting portion 18 fixed to the lower right end of the first annular portion 16, a second annular portion 19 fixed to the inner end of the first connecting portion 18, a second connecting portion 20 fixed to the right end of the second annular portion 19, a third annular portion 21 fixed to the inner end of the second connecting portion 20, and a cover plate 22 fixed to the right end of the third annular portion 21. This is the specific structure of the shielding sleeve 7. Through this structure, the shielding sleeve 7 greatly improves the isolation and sealing effect.

[0032] The outer surface of the first annular portion 16 contacts the inner surface of the pump cover 2, and a first sealing gasket 23 is fixed between the first annular portion 16 and the pump cover 2. An embedding groove matching the second annular portion 17 is provided at the connection between the pump cover 3 and the connecting frame 1. The first annular portion 16 is inserted into the left end of the pump cover 2 for easy installation, and the first sealing gasket 23 greatly enhances the sealing effect between the two. The second annular portion 17 spans across the pump cover 3 and the connecting frame 1, thus blocking the gap between the pump cover 3 and the connecting frame 1 and preventing external liquid from entering the interior of the magnetic pump. To further improve the sealing effect, a sealing gasket can also be provided on the right side of the second annular portion 17.

[0033] The rightmost bushing cap 15 is locked by a round nut 24. The right end of the shaft core 8 has a threaded hole that matches the round nut 24. A washer 25 and a retaining washer 26 are provided between the bushing cap 15 and the round nut 24. By providing a round nut 24, washer 25 and retaining washer 26 at the right end of the shaft core 8, it is ensured that the round nut 24 will be locked even under high temperature conditions, further ensuring axial self-balancing adjustment.

[0034] A first key 27 is fixed on the connecting shaft 13, a second key 28 is fixed on the shaft core 8, and a third key 29 is fixed on the output shaft of the motor 4. The first key 27 enhances the fixation between the connecting shaft 13 and the impeller 14, preventing relative rotation during operation and ensuring reliable torque transmission. The second key 28 enhances the fixation between the shaft core 8 and the inner rotating magnet 6, preventing relative rotation and ensuring reliable torque transmission. The third key 29 enhances the fixation between the output shaft of the motor 4 and the outer rotating magnet 5, preventing relative rotation and ensuring reliable torque transmission. Furthermore, the first, second, and third keys 27, 28, and 29 prevent radial displacement of the shaft core 8.

[0035] A second sealing gasket 30 is provided between the pump cover 2 and the pump body 3. The second sealing gasket 30 seals the pump cover 2 and the pump body 3, further improving the overall sealing performance of the magnetic pump.

[0036] The pump cover 2 has a first through hole 31 and a second through hole 32, and a filter plate is fixed inside the first through hole 31 and the second through hole 32. The first through hole 31 and the second through hole 32 ensure that there is water inside the shielding sleeve 7. This serves two purposes: firstly, it lubricates the bushing 9, bearing 10, and thrust bearing 11, preventing them from dry-running; secondly, it cools the bushing 9, bearing 10, and thrust bearing 11. The filter plate filters the medium, preventing impurities from entering the interior and damaging the magnetic pump.

[0037] An annular connecting block 33 is fixed between the connecting frame 1 and the motor 4. A support base 34 is fixed to the bottom of the connecting frame 1. A cavity 35 is provided inside the support base 34. A cooling mechanism 36 is provided inside the support base 35 and the annular connecting block 33. This structure effectively cools the motor 4, thus providing good protection for the motor 4.

[0038] The cooling mechanism 36 includes an insulation layer 37 disposed on the inner wall of the cavity 35. A water tank 38 and a cooling box 39 are disposed on the bottom wall of the insulation layer 37. The water tank 38 is connected to a water outlet pipe 40, and a water pump 41 is fixed to the water outlet pipe 40. The outer end of the water outlet pipe 40 is detachably connected to the inlet end of a first cooling pipe 42. The outlet end of the first cooling pipe 42 extends out of the cooling box 39, which is filled with ice blocks 43. The outlet end of the first cooling pipe 42 is detachably connected to a second cooling pipe 44, which is disposed within an annular connecting block 33. The outlet end of the second cooling pipe 44 extends into the water tank 38. The support base 34 is equipped with an openable door. The insulation layer 37 insulates the ice blocks 43 in the cooling box 39, increasing their melting time and ensuring the cooling effect. Its working principle is as follows: When the motor 4 starts, the water pump 41 starts. The water pump 41 pumps the water in the water tank 38 to the outlet pipe 40 and the first cooling pipe 42 in sequence. When the water passes through the first cooling pipe 42, it is cooled. The cooled water then enters the second cooling pipe 44 to cool the annular connecting block 33, and then cools the motor 4, the outer rotating magnet 5 and the connecting frame 1 around the annular connecting block 33, which greatly improves the cooling effect. The water passing through the second cooling pipe 44 then enters the water tank 38 to achieve circulating cooling. After the magnetic pump has been used for a period of time, the door on the support base 34 can be opened. First, disconnect the left end of the first cooling pipe 42 from the water outlet pipe 40, then disconnect the right end of the first cooling pipe 42 from the second cooling pipe 44. Next, remove the entire cooling tank 39 and drain any remaining water from the first cooling pipe 42. Then, freeze the entire cooling tank 39 until the water inside is refrozen into ice blocks 43. Afterward, place the entire cooling tank 39 back into its original position in the support base 34, and connect the first cooling pipe to the water outlet pipe 40 and the second cooling pipe 44. Check the water level in the water tank 38 and replenish it if necessary. The first cooling pipe 44 is designed in a meandering shape to enhance the cooling effect. The second cooling pipe 42 is designed in a spiral shape within the annular connecting block 33 to enhance the cooling effect on the annular connecting block 33, thereby enhancing the cooling effect on components such as the motor 4, the external rotating magnet 5, and the connecting frame 1.

[0039] Working principle: During operation, first connect the inlet of pump body 3 to the inlet pipe, which is connected to the medium to be transported. Connect the outlet to the outlet pipe, which is connected to the destination of the medium. Start motor 4, and its output shaft rotates, driving the outer rotating magnet 5 to rotate, which in turn drives the inner rotating magnet 6 to rotate, which in turn drives the shaft core 8 to rotate, which in turn drives the impeller 14 to rotate, thus realizing the transport of the medium. The shielding sleeve 7 completely isolates the outer rotating magnet 5 and the inner rotating magnet 6 from the transported medium, realizing an integrated sealed structure of motor and pump. This invention uses a combination of bushings 9, bearings 10, thrust bearings 11, and thrust bearing seats 12 at both ends of the shaft core 8. The bushings 9 and bearings 10 cooperate as radial supports, with a clearance of 0.05mm-0.1mm, thus ensuring the radial concentricity of the shaft core 8 during operation and preventing radial friction. The combination of bearings 10 and thrust bearings 11 ensures the axial limit of the shaft core 8, with an axial displacement of 0.5mm on one side and 1mm on both sides. When the shaft core 8 rotates and moves axially in multiple directions, when the shaft core 8 moves to the left end, the thrust bearings 12 and 10 at the left end abut against each other, preventing the shaft core 8 from moving further to the left. Instead, it is offset to the right by the reaction force. When the shaft core 8 moves to the right end, the thrust bearings 11 and 10 at the right end abut against each other, preventing the shaft core 8 from moving further to the right, thus achieving self-balancing adjustment of the shaft core 8.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A magnetic pump with self-balanced structure of the shaft core, characterized in that, The device includes a connecting frame (1), with a pump cover (2) and a pump body (3) fixed to the left end of the connecting frame (1) in sequence. A motor (4) is fixed to the right end of the connecting frame (1). An outer rotating magnet (5) is fixed on the output shaft of the motor (4). The outer rotating magnet (5) is provided with an inner rotating magnet (6) that matches it. A shielding sleeve (7) is provided between the inner rotating magnet (6) and the outer rotating magnet (5). A shaft core (8) is fixed to the inner rotating magnet (6). A bushing (9) is fixed to both the left and right ends of the shaft core (8). A bearing (10) and a thrust bearing (11) are connected to the bushing (9). The thrust bearing (11) is fixed on the thrust bearing seat (12). A connecting shaft (13) is fixed to the left end of the shaft core (8). An impeller (14) is fixed on the connecting shaft (13).

2. The self-balanced structure magnetic force pump according to claim 1, wherein, Both ends of the bushing (9) are fixed with bushing caps (15).

3. The self-balanced structure magnetic force pump according to claim 1, wherein, The shielding sleeve (7) includes a first annular portion (16) at the left end, a second annular portion (17) fixed to the upper right end of the first annular portion (16), a first connecting portion (18) fixed to the lower right end of the first annular portion (16), a second annular portion (19) fixed to the inner end of the first connecting portion (18), a second connecting portion (20) fixed to the right end of the second annular portion (19), a third annular portion (21) fixed to the inner end of the second connecting portion (20), and a cover plate (22) fixed to the right end of the third annular portion (21).

4. The self-balanced structure magnetic force pump of claim 3, wherein, The outer surface of the first annular portion (16) is in contact with the inner surface of the pump cover (2), and a first sealing gasket (23) is fixed between the first annular portion (16) and the pump cover (2). An embedded groove matching the second annular portion (17) is provided at the connection between the pump cover (3) and the connecting frame (1).

5. A shaft-driven self-balancing magnetic pump according to claim 2, characterized in that, The rightmost bushing cover (15) is locked by a round nut (24). The right end of the shaft core (8) has a threaded hole that matches the round nut (24). A washer (25) and a stop washer (26) are provided between the bushing cover (15) and the round nut (24).

6. A shaft-driven self-balancing magnetic pump according to claim 1, characterized in that, A first key (27) is fixed on the connecting shaft (13), a second key (28) is fixed on the shaft core (8), and a third key (29) is fixed on the output shaft of the motor (4).

7. A shaft-driven self-balancing magnetic pump according to claim 1, characterized in that, A second sealing gasket (30) is provided between the pump cover (2) and the pump body (3).

8. A shaft-driven self-balancing magnetic pump according to claim 1, characterized in that, The pump cover (2) is provided with a first through hole (31) and a second through hole (32), and a filter plate is fixed in the first through hole (31) and the second through hole (32).

9. A shaft-driven self-balancing magnetic pump according to claim 1, characterized in that, An annular connecting block (33) is fixed between the connecting frame (1) and the motor (4). A support base (34) is fixed at the bottom of the connecting frame (1). A cavity (35) is provided inside the support base (34). A cooling mechanism (36) is provided inside the support base (35) and the annular connecting block (33).

10. A shaft-driven self-balancing magnetic pump according to claim 9, characterized in that, The cooling mechanism (36) includes an insulation layer (37) disposed on the inner wall of the cavity (35). A water tank (38) and a cooling tank (39) are disposed on the bottom wall of the insulation layer (37). The water tank (38) is connected to a water outlet pipe (40). A water pump (41) is fixed on the water outlet pipe (40). The outer end of the water outlet pipe (40) is detachably connected to the inlet end of a first cooling pipe (42). The outlet end of the first cooling pipe (42) extends out of the cooling tank (39). The cooling tank (39) is filled with ice blocks (43). The outlet end of the first cooling pipe (42) is detachably connected to a second cooling pipe (44). The second cooling pipe (44) is disposed in the annular connecting block (33). The outlet end of the second cooling pipe (44) extends into the water tank (38).

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