Nuclear magnetic resonance tube cleaning device

Abstract

The utility model discloses a nuclear magnetic resonance tube cleaning device which comprises a box body, a plurality of cleaning holes are formed in the upper end of the box body, and a plurality of first water outlets are formed in the inner walls of the cleaning holes; a mounting seat is rotationally connected to the bottom of the cleaning cavity, a cleaning column is arranged on the mounting seat, and a plurality of cleaning brushes are arranged on the side part of the cleaning column; an output channel is vertically arranged in the cleaning column; a driving mechanism is arranged in the box body; a plurality of rubber clamping pads are vertically distributed in the cleaning cavity, and round holes are formed in the rubber clamping pads; vertical grooves are symmetrically formed in the rear side of the upper end of the box body, a clear water tank and a sewage tank are separately connected into the vertical grooves, and the clear water tank is connected with a cleaning mechanism; the sewage tank is connected with a sewage discharging mechanism; and the box body is rotationally connected with a first protective cover. The nuclear magnetic resonance tube cleaning device can clean a plurality of nuclear magnetic resonance tubes at the same time, the tube loading step is simple, and the cleaning efficiency is improved.

Description

Technical Field

[0001] This utility model relates to a nuclear magnetic resonance tube cleaning device, belonging to the technical field of cleaning devices. Background Technology

[0002] In today's scientific research and production fields, nuclear magnetic resonance (NMR) spectrometers, by utilizing the differences in the properties of atomic nuclei of different elements to analyze substances, have become a key tool for determining the structure and quantitative analysis of compounds. They play an indispensable role in the research and development and product identification of numerous fields, including pharmaceutical intermediates and fine chemicals. The importance of the NMR tube, as an essential instrument for measuring NMR spectra, is self-evident. However, existing MRI tubes are difficult to clean due to their long and thin shape and deep diameter, and are prone to leaving impurities, which affects the detection accuracy and hinders customers from accurately identifying impurity content and product characterization. To address this, the industry has developed various cleaning devices. For example, Chinese utility model patent CN212792241U discloses an MRI tube cleaning device, which specifically includes a support, a tube sleeve fixedly installed on the support, a tube groove provided in the tube sleeve, a positioning groove provided on the tube sleeve, a column inserted into the positioning groove, a guide column fixedly installed on the column, a slot provided on the column, a stop fixedly installed on the tube sleeve, a spring pin slidably installed on the stop, a guide groove provided on the guide column, a guide ball movably installed in the guide groove, a limit plate fixedly installed on the guide column, a sliding tube slidably installed in the guide groove, and a baffle and a cleaning tube fixedly installed on the sliding tube. The device requires the MRI tube to be inserted into the tube sleeve before the guide column can be installed for cleaning. The process is quite complicated, and only one MRI tube can be cleaned at a time, resulting in slow cleaning efficiency. Utility Model Content

[0003] The purpose of this invention is to provide a nuclear magnetic resonance (NMR) tube cleaning device. This invention can clean multiple NMR tubes simultaneously, and the tube loading process is simple, thus improving cleaning efficiency.

[0004] The technical solution of this utility model is as follows: A nuclear magnetic resonance tube cleaning device includes a housing. Multiple cleaning chambers are linearly distributed on the front upper side of the housing, and multiple first water outlets are provided on the inner walls of the cleaning chambers. A mounting base is rotatably connected to the bottom of each cleaning chamber, and a cleaning column is mounted on the mounting base. Multiple cleaning brushes are provided on the side of the cleaning column. An output channel is vertically arranged inside the cleaning column and communicates with the outside. A driving mechanism is provided inside the housing, and the output end of the driving mechanism is connected to the mounting base. Multiple rubber pads are vertically distributed inside the cleaning chambers, and the rubber pads have round holes. Symmetrical vertical grooves are provided on the rear upper side of the housing, and a clean water tank and a wastewater tank are detachably connected to each groove. The clean water tank is connected to a cleaning mechanism, which is connected to both the first water outlet and the output channel. The wastewater tank is connected to a sewage discharge mechanism. A first protective cover is rotatably connected to the housing.

[0005] The aforementioned MRI tube cleaning device includes a drive mechanism comprising a first synchronous pulley located at the bottom of the mounting base and a motor located inside the housing. The output end of the motor is connected to a second synchronous pulley, which is connected to the first synchronous pulley via a synchronous belt.

[0006] The aforementioned nuclear magnetic resonance tube cleaning device includes a cleaning mechanism comprising a water inlet located at the bottom of a vertical trough, a second water outlet located at the bottom of a clean water tank, and an air inlet located on the side of the tank body; the second water outlet corresponds to the water inlet; the water inlet and the air inlet are connected to a three-way electrically controlled valve via a pipe, the other end of the three-way electrically controlled valve is connected to a first pump body via a pipe, and the output end of the first pump body is connected to the first water outlet and the output channel via a pipe.

[0007] In the aforementioned nuclear magnetic resonance tube cleaning device, vertical rods are symmetrically arranged inside the second water outlet, and rubber plugs are connected to the upper ends of the vertical rods; a support foot is provided at the lower end of the vertical rod; a convex ring is provided on the inner wall of the upper end of the water inlet, and the convex ring cooperates with the support foot.

[0008] The aforementioned MRI tube cleaning device includes a sewage discharge mechanism comprising multiple sewage discharge holes located at the bottom of the cleaning chamber and a second pump body located inside the chamber, wherein the sewage discharge holes are connected to the second pump body via pipes; the vertical groove is provided with protrusions, and the protrusions are provided with drain outlets, which are connected to the second pump body via pipes; the sewage tank is provided with a sewage inlet, which corresponds to the drain outlet.

[0009] In the aforementioned nuclear magnetic resonance tube cleaning device, the upper end of the sewage tank is provided with a connecting rope, the other end of the connecting rope is connected to a connecting rod, and both sides of the connecting rod are provided with suspended balls, and pressure sensors are provided inside the suspended balls.

[0010] In the aforementioned MRI tube cleaning device, both the wastewater tank and the clean water tank are rotatably connected to a second protective cover; a third protective cover is provided at the upper end of the tank body, which covers all cleaning holes and is located inside the first protective cover; the third protective cover is provided with multiple first vent holes; and the first protective cover is provided with multiple second vent holes.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] 1. In this invention, the MRI tube is placed upside down into the cleaning chamber, and the cleaning column is inserted into the tube. At this time, the cleaning brush on the side of the cleaning column contacts the wall of the MRI tube. The MRI tube is then fixed by passing it through the round hole of the rubber clamp, and the elasticity of the rubber clamp secures the MRI tube. The first protective cover is then placed on top. At the start of cleaning, clean water from the clean water tank is sent to the first outlet and the output pipe via the cleaning mechanism to spray and wash the inside and outside of the MRI tube. The cleaning column is rotated by the drive mechanism, thereby cleaning the inside of the MRI tube and further reducing the residue of impurities. After cleaning, the MRI tube is removed, and the wastewater in the cleaning chamber is discharged into the wastewater tank by the sewage discharge mechanism for centralized treatment. Therefore, this invention achieves the effect of cleaning multiple MRI tubes simultaneously, and has the advantages of simple operation and good cleaning effect.

[0013] 2. In this utility model, during the cleaning process of the nuclear magnetic resonance tube, the control board first controls the three-way solenoid valve to connect the water inlet with the first pump body, so that the first pump body can send the clean water in the clean water tank to the first water outlet and the output pipe to spray the nuclear magnetic resonance tube inside and out. Then, the control board controls the three-way solenoid valve to connect the air inlet with the first pump body, so that the first pump body can draw in external air and spray it out from the first water outlet and the output pipe to dry the nuclear magnetic resonance tube inside and out, reducing water stains.

[0014] 3. In this utility model, when the clean water tank is placed in the vertical groove and the support foot is placed on the convex ring, the vertical rod supports the rubber plug so that it does not block the second water outlet, and the water in the clean water tank can flow normally to the water inlet; after the clean water tank is taken out, without the support of the convex ring, the rubber plug moves downward under the action of gravity to block the second water outlet, preventing water leakage during the process of adding water when the clean water tank is taken out.

[0015] 4. In this invention, the suspended ball comes into contact with the sewage in the sewage tank and floats on the surface of the sewage under the action of buoyancy. As the sewage increases, when the water level reaches a certain height, the suspended ball will be squeezed between the sewage surface and the first protective cover. At this time, the pressure sensor is compressed and sends a signal to the control board, and the cleaning program will pause. The operator needs to remove the sewage tank, empty the sewage, and then reinstall the sewage tank into the vertical tank before the cleaning work can continue. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model;

[0017] Figure 2 yes Figure 1 A structural diagram with all protective covers removed;

[0018] Figure 3 This is a cross-sectional view of the cleaning cavity;

[0019] Figure 4 This is a sectional view of the cleaning mechanism;

[0020] Figure 5 yes Figure 4 Enlarged view at point A;

[0021] Figure 6 This is a schematic diagram of the vertical trough where the sewage tank is placed;

[0022] Figure 7 This is a structural diagram of the mounting base.

[0023] The labels in the attached diagram are as follows: 1-Box body, 2-Cleaning cavity, 3-First water outlet, 4-Mounting base, 5-Cleaning column, 6-Cleaning brush, 7-Output channel, 8-Drive mechanism, 9-Rubber pad, 10-Round hole, 11-Vertical groove, 12-Clean water tank, 13-Sewage tank, 14-Cleaning mechanism, 15-Sewage discharge mechanism, 16-First protective cover, 17-Connecting rope, 18-Connecting rod, 19-Suspension ball, 20-Second protective cover, 21-... - Third protective cover, 22- First air outlet, 23- Second air outlet, 30- First synchronous pulley, 31- Motor, 32- Second synchronous pulley, 40- Water inlet, 41- Second water outlet, 42- Air inlet, 43- Three-way electric control valve, 44- First pump body, 45- Vertical rod, 46- Rubber plug, 47- Support foot, 48- Protruding ring, 50- Drain hole, 51- Second pump body, 52- Protrusion, 53- Drain outlet, 54- Sewage inlet. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0025] Example: A nuclear magnetic resonance tube cleaning device, configured as follows Figure 1-7As shown, the device includes a housing 1. Multiple cleaning chambers 2 are linearly distributed on the front upper side of the housing 1. Multiple first water outlets 3 are provided on the inner wall of each cleaning chamber 2. A mounting base 4 is rotatably connected to the bottom of each cleaning chamber 2. A cleaning column 5 is mounted on the mounting base 4. The cleaning column 5 is made of aluminum alloy, making it lightweight and strong. Multiple cleaning brushes 6 are provided on the side of the cleaning column 5. The cleaning brushes 6 are made of nylon, which has good wear resistance and flexibility, effectively removing dirt from the inside of the MRI tube without damaging its inner wall. An output channel 7 is vertically arranged inside the cleaning column 5, connecting to the outside to deliver cleaning water and air into the MRI tube. A drive mechanism 8 is located inside the housing 1. The output end of the drive mechanism 8 is connected to the mounting base 4. The function of the drive mechanism 8 is to drive the cleaning column 5 to rotate, thus achieving the cleaning of the MRI tube. The internal structure of the MRI tube is thoroughly cleaned. Multiple vertically arranged rubber pads 9 are installed in the cleaning chamber 2, each with a round hole 10 for securing the MRI tube and preventing it from shaking during cleaning. Symmetrical vertical grooves 11 are provided on the rear upper side of the chamber 1. A clean water tank 12 and a wastewater tank 13 are detachably connected within each groove 11. Both tanks are made of transparent plastic for easy observation of the internal water level. The clean water tank 12 is connected to a cleaning mechanism 14, which is connected to the first outlet 3 and the output channel 7. The cleaning mechanism 14 provides clean water and air for cleaning and drying the MRI tube. The wastewater tank 13 is connected to a sewage discharge mechanism 15. A first protective cover 16 is rotatably connected to the chamber 1. The first protective cover 16 is made of plastic to effectively prevent water splashing during cleaning.

[0026] Preferably, such as Figure 3 As shown, the drive mechanism 8 includes a first synchronous pulley 30 disposed at the bottom of the mounting base 4 and a motor 31 disposed inside the housing 1. The output end of the motor 31 is connected to a second synchronous pulley 32, which is connected to the first synchronous pulley 30 via a synchronous belt. The motor 31 causes the second synchronous pulley 32 to rotate, which in turn causes the first synchronous pulley 30 to rotate via the synchronous belt, thereby rotating the cleaning column 5 and enabling the cleaning brush 6 to clean the inside of the MRI tube. Further, as... Figure 7 As shown, a protruding post is provided above the first synchronous pulley 30, and the upper end of the protruding post is fixedly connected to the mounting base 4; a rotating bearing is provided on the outer side of the protruding post, and the outer side of the rotating bearing is fixedly connected to the housing; a through hole is provided on the first synchronous pulley 30, and the pipeline connecting the cleaning mechanism 14 and the output channel 7 passes through the through hole.

[0027] Preferably, such as Figure 4As shown, the cleaning mechanism 14 includes a water inlet 40 at the bottom of the vertical trough 11, a second water outlet 41 at the bottom of the clean water tank 12, and an air inlet 42 on the side of the tank body 1; the second water outlet 41 corresponds to the water inlet 40; the water inlet 40 and the air inlet 42 are connected to a three-way solenoid valve 43 via pipes, and the other end of the three-way solenoid valve 43 is connected to a first pump body 44 via a pipe. The first pump body 44 is a miniature pump of model MD-10 manufactured by Wilo GmbH, Germany, which has the characteristics of small size, large flow rate, and low noise; the first pump body 4 The output end of 4 is connected to the first water outlet 3 and the output channel 7 via a pipe. In this embodiment, an integrated circuit board (PCB) can be installed inside the housing 1. This control board integrates a processor and electronic components such as capacitors, resistors, and wireless chips. The processor can be an MCU processor. Since the control board is a conventional component in this field and can be obtained commercially, the specific structure and circuit connection of the circuit board will not be described in detail here. The function of the control board is to coordinate the work of various components and realize the automated control of a series of operations such as cleaning, drying, and sewage discharge. The control board is connected to the three-way solenoid valve 43 and the first pump body 44 via wiring. During the cleaning process of the MRI tube, the control board first controls the three-way solenoid valve 43 to connect the water inlet 40 with the first pump body 44, allowing the first pump body 44 to send clean water from the clean water tank 12 to the first outlet 3 and the output pipe to spray the MRI tube internally and externally. Then, the control board controls the three-way solenoid valve 43 to connect the air inlet 42 with the first pump body 44, allowing the first pump body 44 to draw in external air and spray it out from the first outlet 3 and the output pipe, thus drying the MRI tube internally and externally and reducing water residue. The cleaning mechanism 14 functions to switch between the supply of cleaning water and air, completing both the cleaning and drying steps.

[0028] Preferably, such as Figure 5 As shown, vertical rods 45 are symmetrically arranged inside the second water outlet 41, and rubber plugs 46 are connected to the upper ends of the vertical rods 45. Support legs 47 are provided outwards at the lower ends of the vertical rods 45. A convex ring 48 is provided on the inner wall of the upper end of the water inlet 40, and the convex ring 48 cooperates with the support legs 47. When the clean water tank 12 is placed in the vertical groove 11, the support legs 47 are placed on the convex ring 48, causing the vertical rods 45 to support the rubber plugs 46, preventing them from blocking the second water outlet 41. Water in the clean water tank 12 can flow normally to the water inlet 40. After the clean water tank 12 is removed, without the support of the convex ring 48, the rubber plugs 46 move downwards under the action of gravity, blocking the second water outlet 41 and preventing water leakage during the process of adding water to the clean water tank 12. Furthermore, a filter mesh is surrounded around the second water outlet 41, located outside the rubber plugs 46, to filter particulate impurities in the water and prevent them from damaging the MRI tube during cleaning.

[0029] Preferably, such as Figure 2 and 6As shown, the sewage discharge mechanism 15 includes multiple sewage discharge holes 50 located at the bottom of the cleaning pit 2 and a second pump body 51 located inside the housing 1. The sewage discharge holes 50 are connected to the second pump body 51 via pipes. The second pump body 51 is also a micro pump of model MD-10 manufactured by Wilo GmbH, Germany. A protrusion 52 is provided in the vertical groove 11, and a drain outlet 53 is provided on the protrusion 52. The drain outlet 53 is connected to the second pump body 51 via pipes. A sewage inlet 54 is provided on the sewage tank 13, and the sewage inlet 54 corresponds to the drain outlet 53. The control board is connected to the second pump body 51 via wiring. During the cleaning of the MRI tube, the second pump 51 operates at low power, slowly sucking out the sewage in the cleaning cavity 2. After the MRI tube is cleaned and removed, the second pump 51 increases its output power to suck away as much sewage as possible remaining in the cleaning cavity 2. The sewage is sucked in from the drain hole 50, passes through the corresponding pipe to the second pump 51, and is then transported by the second pump 51 to the drain outlet 53. Since the drain outlet 53 corresponds to and is connected to the sewage inlet 54, the sewage enters the sewage tank 13 for centralized storage.

[0030] Preferably, such as Figure 2 As shown, the upper end of the sewage tank 13 is equipped with a connecting rope 17, and the other end of the connecting rope 17 is connected to a connecting rod 18. Suspended balls 19 are located on both sides of the connecting rod 18, and pressure sensors are installed inside the suspended balls 19. In this embodiment, the pressure sensor is a diffused silicon pressure sensor of model MPM281, whose working principle is based on the piezoresistive effect. When the water level reaches a set height, the suspended balls 19 are squeezed between the sewage surface and the second protective cover 20. The piezoresistive sensitive element inside the sensor changes its resistance value under pressure, and the internal circuit converts the resistance change into an electrical signal, which is then transmitted to the control board via a wireless signal. The suspended balls 19 are in contact with the sewage in the sewage tank 13 and float on the sewage surface under the action of buoyancy. As the sewage increases, when the water level reaches a certain height, the suspended balls 19 are squeezed between the sewage surface and the second protective cover 20. At this time, the pressure sensor is squeezed and sends a signal to the control board, pausing the cleaning process. The operator needs to remove the sewage tank 13, empty the sewage, and then reinstall the sewage tank 13 into the vertical trough 11 before the cleaning work can continue. The purpose of this structure is to prevent the sewage tank 13 from overflowing and to ensure the normal progress of the cleaning work.

[0031] Preferably, such as Figure 1 As shown, both the wastewater tank 13 and the clean water tank 12 are rotatably connected to a second protective cover 20; a third protective cover 21 is provided at the upper end of the tank body 1, covering all the cleaning holes 2 and located inside the first protective cover 16; the third protective cover 21 is provided with multiple first vent holes 22; the first protective cover 16 is provided with multiple second vent holes 23. The first vent holes 22 and the second vent holes 23 are used to discharge water vapor and air generated during the cleaning and drying process to prevent the pressure inside the cleaning holes 2 from becoming too high.

[0032] Working principle:

[0033] Installation: Place the MRI tube upside down into the cleaning cavity 2. The size of the cleaning cavity 2 is compatible with various sizes of MRI tubes. Ensure that the cleaning column 5 enters the tube smoothly, so that the cleaning brush 6 on the side of the cleaning column 5 contacts the MRI tube wall, and that the MRI tube passes through the round hole 10 of the rubber clamp 9. The rubber clamp 9 has good elasticity and will tightly wrap around the MRI tube, securing it firmly and preventing it from shaking or shifting during cleaning. Then, cover it with the first protective cover 16 and the third protective cover 21 to prevent water from splashing out during cleaning and to keep the operating environment clean.

[0034] Cleaning: The control panel controls the three-way solenoid valve 43 to connect the inlet 40 to the first pump body 44. The first pump body 44 draws clean water from the clean water tank 12 and delivers it through the pipeline to the first outlet 3 and the output channel 7. The clean water is sprayed out at high speed, simultaneously cleaning the inside and outside of the MRI tube. At the same time, the motor 31 in the drive mechanism 8 starts, driving the second synchronous pulley 32 to rotate. This, via the synchronous belt, causes the first synchronous pulley 30 to rotate, which in turn rotates the cleaning column 5. The rotating cleaning brush 6 works in conjunction with the sprayed clean water to further reduce the amount of impurities remaining inside the MRI tube, ensuring the cleaning effect. After cleaning, the control panel controls the three-way solenoid valve 43 to connect the air inlet 42 to the first pump body 44. The first pump body 44 draws in external air and sprays it out from the first outlet 3 and the output pipeline, drying the MRI tube inside and out.

[0035] Wastewater Discharge: During the cleaning of the MRI tube, the second pump 51 operates at low power, slowly sucking out the wastewater from the cleaning chamber 2 to prevent it from overflowing. After cleaning, the MRI tube is removed, and the second pump 51 increases its power to remove as much wastewater as possible. The wastewater is transported through a pipeline to the drain outlet 53 on the protrusion 52 in the vertical trough 11. Since the drain outlet 53 is connected to the wastewater inlet 54 of the wastewater tank 13, the wastewater smoothly enters the wastewater tank 13 for collection, facilitating subsequent centralized treatment.

Claims

1. A nuclear magnetic resonance tube cleaning device comprising a housing (1), characterized in that: The box (1) upper end front side linear distribution has a plurality of cleaning holes (2), the inner wall of cleaning hole (2) is provided with a plurality of first water outlet (3); The bottom of the cleaning hole (2) is rotatably connected with the mounting seat (4), the mounting seat (4) is provided with cleaning column (5), the side of cleaning column (5) is provided with a plurality of cleaning brush (6); The output channel (7) is vertically arranged in the cleaning column (5), the output channel (7) is connected with the outside; The box (1) is provided with driving mechanism (8), the output end of driving mechanism (8) is connected with mounting seat (4); The cleaning hole (2) is provided with a plurality of rubber card pad (9) which is vertically distributed, the rubber card pad (9) is provided with a round hole (10); The upper end of the box (1) rear side is provided with vertical groove (11) symmetrically, the vertical groove (11) is respectively separable connected with clean water tank (12) and sewage tank (13), the clean water tank (12) is connected with cleaning mechanism (14), the cleaning mechanism (14) is respectively connected with first water outlet (3) and output channel (7); The sewage tank (13) is connected with sewage discharge mechanism (15); The box (1) is rotatably connected with the first protective cover (16).

2. The NMR tube washing apparatus according to claim 1, wherein: The driving mechanism (8) includes a first synchronous wheel (30) arranged at the bottom of the mounting seat (4) and a motor (31) arranged in the box (1), the output end of the motor (31) is connected with a second synchronous wheel (32), the second synchronous wheel (32) is connected with the first synchronous wheel (30) through a synchronous belt.

3. The NMR tube washing apparatus of claim 1, wherein: The cleaning mechanism (14) includes a water inlet (40) arranged at the bottom of the vertical groove (11), a second water outlet (41) arranged at the bottom of the clean water tank (12) and an air inlet (42) arranged at the side of the box (1); The second water outlet (41) corresponds to the water inlet (40); The water inlet (40) and the air inlet (42) are commonly connected with a three-way electric control valve (43) through a pipeline, the other end of the three-way electric control valve (43) is connected with a first pump body (44) through a pipeline, the output end of the first pump body (44) is connected with the first water outlet (3) and the output channel (7) through a pipeline.

4. The NMR tube washing apparatus according to claim 3, wherein: The second water outlet (41) is symmetrically provided with a vertical rod (45), the upper end of the vertical rod (45) is commonly connected with a rubber plug (46); The lower end of the vertical rod (45) is provided with a supporting leg (47) outwardly; The upper end inner wall of the water inlet (40) is provided with a convex ring (48), the convex ring (48) is matched with the supporting leg (47).

5. The NMR tube washing apparatus of claim 1, wherein: The sewage discharge mechanism (15) includes a plurality of sewage discharge holes (50) arranged at the bottom of the cleaning hole (2) and a second pump body (51) arranged in the box (1), the sewage discharge holes (50) are connected with the second pump body (51) through a pipeline; The vertical groove (11) is provided with a protruding block (52), the protruding block (52) is provided with a drain port (53), the drain port (53) is connected with the second pump body (51) through a pipeline; The sewage tank (13) is provided with a sewage inlet (54), the sewage inlet (54) corresponds to the drain port (53).

6. The NMR tube washing apparatus of claim 1, wherein: The upper end of the sewage tank (13) is provided with a connecting rope (17), the other end of the connecting rope (17) is connected with a connecting rod (18), the two sides of the connecting rod (18) are provided with floating balls (19), and the floating balls (19) are provided with pressure sensors.

7. The NMR tube washing apparatus of claim 1, wherein: The sewage tank (13) and the clean water tank (12) are rotatably connected with second protective covers (20); the upper end of the box body (1) is provided with a third protective cover (21), the third protective cover (21) covers all the cleaning holes (2) and is located on the inner side of the first protective cover (16); a plurality of first air outlets (22) are arranged on the third protective cover (21); a plurality of second air outlets (23) are arranged on the first protective cover (16).

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