High-efficiency low-temperature refrigeration system based on direct-current frequency conversion

Abstract

The application discloses a kind of based on high-efficiency low-temperature refrigeration system of direct current frequency conversion, belong to refrigeration equipment technical field, including main circuit and jet augmenting circuit, main circuit includes compressor, condenser, liquid accumulator, filter, sight mirror, economizer, first electronic expansion valve, evaporator, gas-liquid separator connected by pipeline in sequence, jet augmenting circuit includes second electronic expansion valve, economizer, compressor connected by pipeline in sequence;Gas-liquid separator includes bin body and filter cartridge, the two side end surfaces of bin body are respectively provided with coaxial residue inlet and residue outlet, and the two ends of filter cartridge are communicated with residue inlet and residue outlet respectively, the lower side and upper side of bin body form liquid collection bin and gas collection bin respectively, the liquid outlet of liquid collection bin is connected to evaporator, and the gas outlet of gas collection bin is connected to compressor.The system can timely remove impurities in the device to ensure the running efficiency of the device.

Description

Technical Field

[0001] This invention belongs to the field of refrigeration equipment technology, specifically relating to a high-efficiency low-temperature refrigeration system based on DC frequency conversion. Background Technology

[0002] Semiconductor manufacturing processes are constantly improving. Traditional refrigeration systems can operate stably at room temperature, but their refrigeration efficiency drops significantly at low temperatures, sometimes even failing to maintain the required low-temperature environment. To improve low-temperature performance, modern refrigeration systems typically employ DC inverter technology combined with vapor injection enthalpy enhancement technology to improve the compressor's heating / cooling capacity and optimize the system's energy efficiency ratio. The core function of a cryogenic refrigeration system is to maintain stable refrigeration capacity even at extremely low ambient temperatures. Its working principle mainly relies on the four basic processes in the refrigeration cycle: evaporation, compression, condensation, and throttling. At low temperatures, due to the decrease in evaporation temperature, the compressor's suction pressure drops, leading to a reduction in refrigerant mass flow rate and a sharp decline in system refrigeration capacity. To address this issue, vapor injection enthalpy enhancement technology has been introduced. Its core idea is to inject additional gaseous refrigerant into the compressor's economizer during the compression process to increase refrigerant flow rate and improve system enthalpy, thereby improving low-temperature performance. The gas-liquid separation device in the vapor injection enthalpy enhancement system plays a crucial role, ensuring that the refrigerant entering the compressor is a pure gaseous state. However, existing jet enthalpy-enhancing refrigeration systems still face some technical bottlenecks in actual operation, particularly in the management of impurities in the gas-liquid separation unit. Due to long-term operation of the refrigeration system, lubricating oil may produce carbonized particles due to high-temperature oxidation, trace amounts of moisture in the refrigerant may cause corrosion of metal pipelines, and solid impurities such as welding slag and metal fragments remaining during welding or assembly may also enter the gas-liquid separation unit with the refrigerant circulation, thereby reducing the refrigeration efficiency of the unit. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a high-efficiency cryogenic refrigeration system based on DC frequency conversion, which can remove impurities in the device in a timely manner to ensure the operating efficiency of the device.

[0004] To achieve the above objectives, the present invention provides the following technical solution: This invention discloses a high-efficiency cryogenic refrigeration system based on DC frequency conversion, comprising a main circuit and a vapor injection enthalpy-increasing circuit. The main circuit includes a compressor, a condenser, a liquid receiver, a filter, a sight glass, an economizer, a first electronic expansion valve, an evaporator, and a gas-liquid separator connected in sequence via pipelines. The vapor injection enthalpy-increasing circuit includes a second electronic expansion valve, an economizer, and a compressor connected in sequence via pipelines. The gas-liquid separator includes a chamber and a filter cartridge. The two end faces of the chamber are respectively provided with coaxial slag inlet and slag outlet, which connect the two ends of the filter cartridge. The lower and upper sides of the chamber form a liquid collection chamber and a gas collection chamber, respectively. The liquid outlet of the liquid collection chamber is connected to the evaporator, and the gas outlet of the gas collection chamber is connected to the compressor. The filter cartridge is installed on the upper side of the liquid collection chamber. A rotating shaft is coaxially installed at the center of the filter cartridge. The rotating shaft is rotatably engaged with the chamber. The rotating shaft is connected to a rotation drive device, and a spiral blade is installed on the outer side of the rotating shaft.

[0005] Furthermore, the filter cylinder includes a left end face ring and a right end face ring arranged in parallel and spaced apart. The left end face ring and the right end face ring correspond to the slag inlet and slag outlet, respectively. Multiple support plates are connected between the left end face ring and the right end face ring. The support plates are evenly distributed along the circumference of the left end face ring. The support plates have a rectangular plate structure, and the width direction of the support plates is along the radial direction of the left end face ring. The length direction of the support plates is along the axial direction of the filter cylinder. A filter slit is formed between two adjacent support plates for filtering impurities. The support plates are made of spring steel.

[0006] Furthermore, the spiral blades are a continuous spiral ribbon structure, with the outer edge of the spiral blades contacting the inner edge of the support plate, the pitch of the spiral blades being constant, and the root of the spiral blades being tightly connected to the rotating shaft; a cylindrical frame is installed on the outside of the filter cartridge, and a first scraper assembly is installed on the cylindrical frame, which is used to scrape off impurities from the surface of the spiral blades.

[0007] Furthermore, the cylindrical frame includes longitudinal beams evenly distributed along the circumference and arc-shaped rods connecting the longitudinal beams, with longitudinal grooves formed on the longitudinal beams; the first scraper assembly includes a slider, a shaft, a scraper body, and an elastic tensioning device, the diameter of the shaft is larger than the width of the filter slot, the slider is connected to the scraper body through the shaft, the slider is slidably installed in the longitudinal groove, the shaft passes through the filter slot and is connected to the scraper body, and the slider is connected to the chamber through the elastic tensioning device, which provides elastic tension to the scraper body toward the spiral blades.

[0008] Furthermore, multiple flexible scraping sections are arranged and installed on the scraper body. The flexible scraping sections are detachably connected to the scraper body and are in contact with one side surface of the spiral blade.

[0009] Furthermore, a second scraper assembly is installed on the cylindrical frame. The structure and connection method of the second scraper assembly are the same as those of the first scraper assembly. The tension direction of the elastic tension device of the second scraper assembly is opposite to that of the elastic tension device of the first scraper assembly. The flexible scraping part of the second scraper assembly is in contact with the other side surface of the spiral blade.

[0010] Furthermore, the slider is connected to the orthopedic block via the support plate, and at least three orthopedic plates are installed at intervals on the orthopedic block. The shape of the orthopedic plates is adapted to the shape of the filter seam, and the orthopedic plates are inserted into the filter seam to orthodont the support plate.

[0011] Furthermore, a feeding hopper is provided at the front end of the silo body, and a feeding port is opened on the feeding hopper. The feeding hopper is connected to the silo body through the slag inlet. The spiral blades can bring the material in the feeding hopper into the silo body. A baffle is slidably installed on the outside of the rotating shaft. The baffle is connected to a limit plate through an elastic support device. The limit plate is fixed to the outer end of the rotating shaft. The baffle is used to close the slag outlet.

[0012] Furthermore, a partition is installed inside the liquid collection tank, which divides the liquid collection tank into a front oil storage tank and a rear liquid storage tank. A hopper is installed inside the oil storage tank, and a bucket cylinder is slidably sealed on the outside of the hopper. The bucket cylinder is connected to a displacement drive device that can drive its up and down movement. The port plane of the bucket cylinder is higher than the partition.

[0013] The beneficial effects of this invention are as follows: This invention discloses a high-efficiency cryogenic refrigeration system based on DC inverter technology. Utilizing a DC inverter compressor and vapor injection enthalpy enhancement technology, it improves energy efficiency in cryogenic applications. Both the vapor injection enthalpy enhancement section and the main refrigeration circuit employ electronic expansion valves as throttling devices, ensuring the system's safety and efficiency under all applicable operating conditions. The mixed liquid can be filtered through a filter cartridge into a collection tank. By employing spiral blades, impurities within the filter cartridge are discharged, achieving real-time impurity removal, reducing contamination and downtime risks, and improving overall system efficiency.

[0014] Other advantages, objectives, and features of the invention will be set forth in the following description and will be apparent to those skilled in the art in some respects, or may be learned by practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0015] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration: Figure 1 This is a schematic diagram of the refrigeration system of the present invention; Figure 2 This is a schematic diagram of a gas-liquid separator. Figure 3 This is a cross-sectional view of a gas-liquid separator; Figure 4 This is a schematic diagram of the cylindrical frame structure; Figure 5 This is a schematic diagram of the structure of the first scraper assembly; Figure 6 This is a schematic diagram showing the location of the second scraper assembly; Figure 7 This is a schematic diagram of the filter cartridge structure; Figure 8 for Figure 7 Enlarged view of point A in the middle; Figure 9 This is a schematic diagram showing the fit between the shaft and the filter slot.

[0016] The components in the attached diagram are labeled as follows: 1. Compressor; 2. Condenser; 3. Liquid receiver; 4. Filter; 5. Sight glass; 6. Economizer; 7. First electronic expansion valve; 8. Evaporator; 9. Gas-liquid separator; 10. Second electronic expansion valve; 11. Chamber; 12. Filter cylinder; 13. Slag inlet; 14. Slag outlet; 15. Liquid collection chamber; 16. Gas collection chamber; 17. Rotary shaft; 18. Rotation drive device; 19. Spiral blade; 20. Left end face ring; 21. Right end face ring; 22. Support plate; 23. Filter slot; 24. Cylindrical frame. 24. First scraper assembly; 25. Longitudinal beam; 26. Arc rod; 27. Longitudinal groove; 28. Slider; 29. ​​Shaft rod; 30. Scraper body; 31. Elastic tensioning device; 32. Flexible scraping part; 33. Second scraper assembly; 34. Support plate; 35. Correcting block; 36. Correcting piece; 37. Feed bin; 38. Feed inlet; 39. Baffle; 40. Elastic support device; 41. Limiting plate; 42. Partition plate; 43. Oil storage tank; 44. Liquid storage tank; 45. Hopper; 46. Bucket cylinder; 47. Displacement driving device; 48. Detailed Implementation

[0017] like Figures 1-9As shown, the high-efficiency low-temperature refrigeration system based on DC frequency conversion disclosed in this invention includes a main circuit and a vapor injection enthalpy-increasing circuit. The main circuit includes a compressor 1, a condenser 2, a liquid receiver 3, a filter 4, a sight glass 5, an economizer 6, a first electronic expansion valve 7, an evaporator 8, and a gas-liquid separator 9 connected in sequence through pipelines. The vapor injection enthalpy-increasing circuit includes a second electronic expansion valve 10, an economizer 6, and a compressor 1 connected in sequence through pipelines. In the above structure, the compressor 1 compresses the low-temperature, low-pressure gaseous refrigerant into a high-temperature, high-pressure gas to provide power for the refrigeration cycle. The high-temperature, high-pressure refrigerant gas exchanges heat with the outside air / water in the condenser 2, releasing latent heat and condensing into a high-pressure liquid. The liquid receiver 3 is used to balance system load fluctuations and ensure that the refrigerant before the expansion valve is a pure liquid. The filter 4 filters solid particles in the refrigerant in advance. The refrigerant status is displayed by color change through the transparent observation window of the sight glass 5 combined with a humidity indicator. During operation, the main circuit is throttled by the first electronic expansion valve 7, and the gas flashed by the economizer 6 is injected into the compressor 1 after being regulated by the second electronic expansion valve 10. The principles and functions of the above-mentioned components are all existing technologies that can be understood by those skilled in the art. By using jet enthalpy enhancement and frequency conversion control, the annual energy consumption is reduced.

[0018] The gas-liquid separator 9 includes a chamber 11 and a filter cylinder 12. The two end faces of the chamber 11 are respectively provided with a coaxial slag inlet 13 and a slag outlet 14, which connect the two ends of the filter cylinder 12. The lower and upper sides of the chamber 11 form a liquid collection chamber 15 and a gas collection chamber 16, respectively. The liquid outlet of the liquid collection chamber 15 is connected to the evaporator 8, and the gas outlet of the gas collection chamber 16 is connected to the compressor 1. The filter cylinder 12 is installed on the upper side of the liquid collection chamber 15. A rotating shaft 17 is coaxially installed at the center of the filter cylinder 12. The rotating shaft 17 is rotatably engaged with the chamber 11. The rotating shaft 17 is connected to a rotation drive device 18, and a spiral blade 19 is installed on the outer side of the rotating shaft 17.

[0019] The design of the filter cartridge 12 and the spiral blade 19 in this invention improves the impurity retention rate and effectively prevents impurities from entering the compressor 1 and causing wear. The separate design of the liquid collection chamber 15 and the gas collection chamber 16 ensures that only pure gaseous refrigerant enters the compressor 1, while the liquid refrigerant returns to the evaporator 8, significantly improving the system's operational stability. Simultaneously, this invention, through the rotating spiral blade 19 in conjunction with the filter cartridge 12, can separate impurities from the refrigerant in real time and transport them to the slag outlet 14, avoiding the clogging problem of traditional screen separators, reducing equipment contamination and downtime risks, and improving equipment efficiency.

[0020] In this embodiment, the filter cylinder 12 includes a left end face ring 20 and a right end face ring 21 arranged in parallel at intervals. The left end face ring 20 and the right end face ring 21 correspond to the slag inlet 13 and the slag outlet 14, respectively. Multiple support plates 22 are connected between the left end face ring 20 and the right end face ring 21, forming a stable cylindrical support structure. The support plates 22 are evenly distributed along the circumference of the left end face ring 20. The support plates 22 have a rectangular plate structure, and the width direction of the support plates 22 is along the radial direction of the left end face ring 20, so that the device can withstand greater radial and axial pressure and reduce deformation.

[0021] The length of the support plate 22 is along the axial direction of the filter cylinder 12. A filter slit 23 for filtering impurities is formed between two adjacent support plates 22. The width of the filter slit 23 is wide enough for liquid to pass through, but not wide enough for impurities to pass through, thus ensuring the filtration effect. The support plate 22 is made of spring steel. After being bent in the middle, it can be restored to its original position in time to prevent filtration failure caused by permanent deformation.

[0022] The arrangement of the support plate 22 in this invention has a self-cleaning effect. When encountering larger particles, the support plate 22 can elastically deform to temporarily widen the gap and avoid blockage. When the spiral blade 19 rotates, its outer edge continuously rubs against the inner edge of the support plate 22, and the resulting high-frequency vibration can prevent impurities from getting stuck in the filter slit 23. Of course, in order to further prevent impurities from entering the evaporator 8, a corresponding filter structure needs to be installed in the liquid outlet pipe for timely cleaning.

[0023] In this embodiment, the spiral blade 19 is a continuous spiral ribbon structure. The outer edge of the spiral blade 19 contacts the inner edge of the support plate 22. The pitch of the spiral blade 19 is constant, and the root of the spiral blade 19 is tightly connected to the rotating shaft 17. A cylindrical frame 24 is installed on the outside of the filter cartridge 12, and a first scraper assembly 25 is installed on the cylindrical frame 24. The first scraper assembly 25 is used to scrape off impurities from the surface of the spiral blade 19. The innovative design of the first scraper assembly 25 solves the problem of impurity adhesion on the surface of the spiral blade 19, further reducing impurity residue.

[0024] In this embodiment, the cylindrical frame 24 includes longitudinal beams 26 evenly distributed along the circumference and arc-shaped rods 27 connecting the longitudinal beams 26. Longitudinal grooves 28 are formed on the longitudinal beams 26. The first scraper assembly 25 includes a slider 29, a shaft 30, a scraper body 31, and an elastic tensioning device 32. The diameter of the shaft 30 is larger than the width of the filter slot 23. The slider 29 is connected to the scraper body 31 via the shaft 30 and is slidably installed within the longitudinal groove 28. The shaft 30 passes through the filter slot 23 and connects to the scraper body 31. The slider 29 is connected to the chamber 11 via the elastic tensioning device 32, which provides elastic tension to the scraper body 31 towards the spiral blades 19. Through the cooperation of the slider 29 and the longitudinal groove 28, linear displacement of the scraper body 31 can be achieved. The thrust is achieved by the spiral blades 19, and then elastic tension is provided by the elastic tensioning device 32. The rotation drive device 18 uses a motor. When the motor rotates in the reverse direction, it can drive the scraper body 31 back to its original position.

[0025] The working principle and process of this invention are as follows: First, the motor rotates forward, driving the rotating shaft 17 and the spiral blade 19 to rotate. The spiral blade 19 pushes impurities from the filter cylinder 12 to the slag outlet 14 at the right end. The spiral blade 19 also drives the scraper body 31 to move linearly, continuously scraping away impurities from the surface of the spiral blade 19 until the scraper body 31 reaches its right limit position. A certain amount of space is left inside the bin 11 on the right side for the scraper body 31. After a period of operation, the motor reverses. As the spiral blade 19 continuously rotates, the elastic tensioning device 32 controls the slider 29 and the scraper body 31 to return to their original positions, restarting the cleaning cycle of impurities on the surface of the spiral blade 19.

[0026] In this embodiment, multiple flexible scraping parts 33 are arranged and installed on the scraper body 31. The flexible scraping parts 33 are made of rubber, which can reduce damage to the blades. The flexible scraping parts 33 are detachably connected to the scraper body 31, which can be easily replaced. The arrangement of multiple scraping parts forms a stepped scraping effect, which can better facilitate contact and adhesion to the blade surface. The flexible scraping parts 33 contact one side surface of the spiral blade 19.

[0027] In this embodiment, a second scraper assembly 34 is installed on the cylindrical frame 24. The structure and connection method of the second scraper assembly 34 are the same as those of the first scraper assembly 25. The pulling direction of the elastic tension device 32 of the second scraper assembly 34 is opposite to that of the elastic tension device 32 of the first scraper assembly 25. The flexible scraping part 33 of the second scraper assembly 34 contacts the other side surface of the spiral blade 19, which can clean the other side surface of the spiral blade 19 and improve the cleaning effect.

[0028] In this embodiment, the slider 29 is connected to the orthotic block 36 via the support plate 35. At least three orthotic pieces 37 are installed at intervals on the orthotic block 36. The shape of the orthotic piece 37 is adapted to the shape of the filter slit 23. The orthotic piece 37 is installed on the front and rear sides of the shaft 30. When the shaft 30 compresses and deforms its corresponding two support pieces 22, the orthotic piece 37 can extend into the filter slit 23 to orthoticize the support piece 22, thereby preventing permanent deformation of the support piece 22.

[0029] In this embodiment, a feeding hopper 38 is provided at the front end of the hopper body 11. The feeding hopper 38 has an inlet 39. The feeding hopper 38 is connected to the hopper body 11 through the slag inlet 13. The spiral blades 19 can bring the material in the feeding hopper 38 into the hopper body 11, which can facilitate the transportation of the material. A baffle 40 is slidably installed on the outer side of the rotating shaft 17. The baffle 40 is connected to a limiting plate 42 through an elastic support device 41. The limiting plate 42 is fixed to the outer end of the rotating shaft 17. The baffle 40 is used to close the slag outlet 14. By setting the baffle 40, the internal impurity mixture is elastically closed. Under the elastic pre-compression of the baffle 40, the filtration time and space of the mixture are increased, and the overflow waste is reduced. When the impurities accumulate and reach a certain pressure, the baffle 40 can be released in time to facilitate the timely discharge of impurities.

[0030] In this embodiment, a partition 43 is installed inside the liquid collection tank 15, which divides the liquid collection tank 15 into a front oil storage tank 44 and a rear liquid storage tank 45. A hopper 46 is installed inside the oil storage tank 44, and a bucket cylinder 47 is slidably sealed on the outside of the hopper 46. The bucket cylinder 47 is connected to a displacement drive device 48 that can drive its up and down displacement. The displacement drive device 48 has a fast response time and can adjust the oil level in real time according to the system load. The port plane of the bucket cylinder 47 is higher than that of the partition 43, which realizes the effective separation of lubricating oil, refrigerant, impurities and gas.

[0031] Finally, it should be noted that the above preferred 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 through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A high-efficiency cryogenic refrigeration system based on DC frequency conversion, characterized in that: The system includes a main circuit and a vapor injection enthalpy-enhancing circuit. The main circuit includes a compressor, condenser, liquid receiver, filter, sight glass, economizer, first electronic expansion valve, evaporator, and gas-liquid separator connected in sequence via pipelines. The vapor injection enthalpy-enhancing circuit includes a second electronic expansion valve, economizer, and compressor connected in sequence via pipelines. The gas-liquid separator includes a chamber and a filter cartridge. The two end faces of the chamber have coaxial slag inlet and slag outlet, which connect to the two ends of the filter cartridge. The lower and upper sides of the chamber form a liquid collection chamber and a gas collection chamber, respectively. The liquid outlet of the liquid collection chamber is connected to the evaporator, and the gas outlet of the gas collection chamber is connected to the compressor. The filter cartridge is installed on the upper side of the liquid collection chamber. A rotating shaft is coaxially installed at the center of the filter cartridge. The rotating shaft is rotatably engaged with the chamber and is connected to a rotation drive device. Spiral blades are installed on the outer side of the rotating shaft. The filter cylinder includes a left end face ring and a right end face ring arranged in parallel and spaced apart. The left end face ring and the right end face ring correspond to the slag inlet and slag outlet, respectively. Multiple support plates are connected between the left end face ring and the right end face ring. The support plates are evenly distributed along the circumference of the left end face ring. The support plates have a rectangular plate structure, and the width direction of the support plates is along the radial direction of the left end face ring. The length direction of the support plates is along the axial direction of the filter cylinder. A filter slit is formed between two adjacent support plates for filtering impurities. The support plates are made of spring steel. The spiral blades are a continuous spiral ribbon structure. The outer edge of the spiral blades contacts the inner edge of the support plate. The pitch of the spiral blades is constant. The root of the spiral blades is tightly connected to the rotating shaft. A cylindrical frame is installed on the outside of the filter cartridge. A first scraper assembly is installed on the cylindrical frame. The first scraper assembly is used to scrape off impurities from the surface of the spiral blades. The cylindrical frame includes longitudinal beams evenly distributed along the circumference and arc-shaped rods connecting the longitudinal beams. The longitudinal beams are provided with longitudinal grooves. The first scraper assembly includes a slider, a shaft, a scraper body, and an elastic tensioning device. The diameter of the shaft is larger than the width of the filter gap. The slider is connected to the scraper body through the shaft. The slider is slidably installed in the longitudinal groove. The shaft passes through the filter gap and is connected to the scraper body. The slider is connected to the chamber through the elastic tensioning device, which provides elastic tension to the scraper body toward the spiral blades.

2. The high-efficiency cryogenic refrigeration system based on DC frequency conversion according to claim 1, characterized in that: Multiple flexible scraping sections are arranged and installed on the scraper body. The flexible scraping sections are detachably connected to the scraper body and are in contact with one side surface of the spiral blade.

3. The high-efficiency cryogenic refrigeration system based on DC frequency conversion according to claim 2, characterized in that: A second scraper assembly is installed on the cylindrical frame. The structure and connection method of the second scraper assembly are the same as those of the first scraper assembly. The tension direction of the elastic tension device of the second scraper assembly is opposite to that of the elastic tension device of the first scraper assembly. The flexible scraping part of the second scraper assembly is in contact with the other side surface of the spiral blade.

4. The high-efficiency cryogenic refrigeration system based on DC frequency conversion according to claim 3, characterized in that: The slider is connected to the orthopedic block via the support plate. At least three orthopedic plates are installed at intervals on the orthopedic block. The shape of the orthopedic plates is adapted to the shape of the filter seam. The orthopedic plates are inserted into the filter seam to orthodont the support plate.

5. The high-efficiency cryogenic refrigeration system based on DC frequency conversion according to claim 1, characterized in that: The front end of the silo is equipped with a feeding silo with a feeding port. The feeding silo is connected to the silo body through the slag inlet. The spiral blades can carry the material in the feeding silo into the silo body. A baffle is slidably installed on the outside of the rotating shaft. The baffle is connected to a limit plate through an elastic support device. The limit plate is fixed to the outer end of the rotating shaft. The baffle is used to close the slag outlet.

6. The high-efficiency cryogenic refrigeration system based on DC frequency conversion according to any one of claims 1-5, characterized in that: The liquid collection tank is equipped with a partition, which divides the liquid collection tank into a front oil storage tank and a rear liquid storage tank. The oil storage tank is equipped with a hopper, and a bucket cylinder is slidably sealed on the outside of the hopper. The bucket cylinder is connected to a displacement drive device that can drive its up and down movement. The port plane of the bucket cylinder is higher than the partition.

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