Extruder vacuum apparatus

Abstract

The application discloses an extruder vacuum device, which comprises a sediment tank, a cold and heat exchanger, a vacuum pump and an exhaust device. The air inlet of the sediment tank is connected with the air outlet of the extruder, and the sediment tank is provided with a first condensing assembly. The air inlet of the cold and heat exchanger is connected with the air outlet of the sediment tank through a first air inlet pipe, and the first air inlet pipe is provided with a first valve. The air outlet of the cold and heat exchanger is connected with a first air outlet pipe, and the first air outlet pipe is provided with a second valve. The cold and heat exchanger is provided with a second condensing assembly. The air outlet of the vacuum pump is connected with the first air outlet pipe of the two cold and heat exchangers. The air inlet of the exhaust device is connected with the air outlet of the vacuum pump, and the exhaust device is provided with a third condensing assembly. The air outlet of the exhaust device is provided with a filtering assembly, and the filtering assembly is used for filtering gas. The extruder vacuum device can start another cold and heat exchanger while cleaning the cold and heat exchanger, and the whole machine does not need to be stopped, so that the working efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of extruders, in particular to an extruder vacuum device. BACKGROUND

[0002] The extruder is one of the machines for processing plastics, and the general principle of processing plastics is as follows: first, the plastic material is loaded into the extruder, the extruder moves and transports the plastic raw material, in the process of transporting the material, the extruder heats the plastic material, and the heated plastic material is in a viscous flow state, and the plastic in the viscous flow state is processed into a plastic finished product through a die; in order to improve the quality of the processed plastic and make the particles of the plastic more compact, the extruder needs to be vacuumized. The current vacuum device is prone to blockage in the interior of the heat exchanger after a period of gas exchange, which needs to be stopped for cleaning, affecting the work efficiency, and the gas purification is not complete, which will cause pollution in the atmosphere. SUMMARY

[0003] The present application aims to at least solve one of the technical problems in the related art. To this end, the present application provides an extruder vacuum device.

[0004] The present application provides an extruder vacuum device, which comprises:

[0005] A sediment tank, the gas inlet of the sediment tank is connected with the gas outlet of the extruder, the first condensing assembly is arranged in the sediment tank, and the first condensing assembly is used for condensing gas and precipitating impurities carried by the gas;

[0006] Two cold heat exchangers, the gas inlets of the cold heat exchangers are connected with the gas outlet of the sediment tank through a first gas inlet pipe, the first gas inlet pipe is provided with a first valve, the gas outlets of the cold heat exchangers are connected with a first gas outlet pipe, the first gas outlet pipe is provided with a second valve, and the second condensing assembly is arranged in the cold heat exchanger, and the second condensing assembly is used for condensing gas;

[0007] A vacuum pump, the gas outlets of the vacuum pump are respectively connected with the first gas outlet pipes of the two cold heat exchangers;

[0008] An exhaust device, the gas inlet of the exhaust device is connected with the gas outlet of the vacuum pump, the third condensing assembly is arranged in the exhaust device, the third condensing assembly is used for condensing gas, and the filter assembly is arranged at the gas outlet of the exhaust device, and the filter assembly is used for filtering gas.

[0009] According to the extruder vacuum device, the following technical effects are achieved: the gas of the extruder is preliminarily condensed and precipitated in the precipitation tank; the first valve and the second valve of one of the cold heat exchangers are controlled to be opened, and the first valve and the second valve of the other cold heat exchanger are controlled to be closed, so that the gas in the precipitation tank is condensed in one of the cold heat exchangers, and the other cold heat exchanger can be cleaned and maintained; the gas in the cold heat exchanger is condensed and then enters the exhaust device for further condensation, and then is discharged through the filter assembly. The precipitation tank of the extruder vacuum device can preliminarily precipitate the gas, reduce the possibility of gas blocking the cold heat exchanger, and when the cold heat exchanger needs to be cleaned, the other cold heat exchanger can be used at the same time without stopping the whole machine, thereby improving the work efficiency, and the filter assembly can filter the gas to avoid pollution of the outside.

[0010] According to some embodiments of the present application, the bottom of the precipitation tank is connected with a first blowdown pipe, the first condensing assembly comprises a first water inlet pipe, a first water outlet pipe and a first condensing pipe, the first condensing pipe is in a U shape, two ends of the first condensing pipe are connected with the first water inlet pipe and the first water outlet pipe respectively, the first condensing pipe is located in the precipitation tank, the first condensing pipe divides the inner cavity of the precipitation tank into a first chamber and a second chamber, and the first condensing pipe has a gap with the bottom of the precipitation tank to make the first chamber and the second chamber communicate; the gas inlet of the precipitation tank communicates with the first chamber, and the gas outlet of the precipitation tank communicates with the second chamber.

[0011] According to some embodiments of the present application, the bottom of the cold heat exchanger is connected with a second blowdown pipe, and the second condensing assembly comprises a second water inlet pipe, a second water outlet pipe and a plurality of second condensing pipes, the second condensing pipes are located in the cold heat exchanger, and two ends of each second condensing pipe are connected with the second water inlet pipe and the second water outlet pipe respectively.

[0012] According to some embodiments of the present application, the cold heat exchanger is provided with a first partition plate and a second partition plate, the first partition plate divides the cold heat exchanger into a first area and a second area, the first area is located above the second area, the second partition plate divides the first area into a water inlet area and a water outlet area, the second condensing pipes are located in the second area, the second condensing pipes are in a U shape, two ends of each second condensing pipe are connected with the water inlet area and the water outlet area respectively, and the first gas inlet pipe and the first gas outlet pipe are connected with the second area respectively.

[0013] According to some embodiments of the present application, the gas inlet of the cold heat exchanger is lower than the gas outlet of the cold heat exchanger.

[0014] According to some embodiments of the present application, the cold heat exchanger is connected with a blowing pipe, the blowing pipe is connected with the second area, the connection end of the blowing pipe with the cold heat exchanger is higher than the connection end of the first air inlet pipe with the cold heat exchanger, and the blowing pipe is used for blowing and washing oil stains adhered to the inner wall of the second condensing pipe and the cold heat exchanger.

[0015] According to some embodiments of the present application, the exhaust device is provided with an annular partition plate, the annular partition plate divides the inner cavity of the exhaust device into an annular area and a middle area, the exhaust device is connected with a second air inlet pipe and a second air outlet pipe respectively, the second air inlet pipe and the second air outlet pipe are both communicated with the middle area, the air outlet of the vacuum pump is connected with the second air inlet pipe, the lower end of the second air outlet pipe is connected with the top of the exhaust device, and the filter assembly is arranged in the second air outlet pipe.

[0016] According to some embodiments of the present application, the third condensing assembly comprises a third water inlet pipe, a third water outlet pipe and a third condensing pipe, the third condensing pipe is located in the middle area, the third water inlet pipe is connected with the annular area and one end of the third condensing pipe respectively, and the third water outlet pipe is connected with the annular area and the other end of the third condensing pipe respectively.

[0017] According to some embodiments of the present application, the filter assembly comprises filter cotton and an air extractor, the filter cotton is located above the air extractor, and the air extractor is used for extracting gas out of the exhaust device.

[0018] According to some embodiments of the present application, the exhaust device is connected with an oil return pipe, the oil return pipe is connected with the middle area and the vacuum pump respectively.

[0019] Additional aspects and advantages of the present application will be made apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0020] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0021] Figure 1 is a structural schematic diagram of an extruder vacuum device according to some embodiments of the present application;

[0022] Figure 2 is a partial structural schematic diagram of an extruder vacuum device according to some embodiments of the present application;

[0023] Figure 3 is a partial structural schematic diagram of an extruder vacuum device according to some embodiments of the present application;

[0024] Figure 4is a partial structural schematic diagram of an extruder vacuum device according to some embodiments of the present application.

[0025] Reference Signs:

[0026] The sediment tank 100, the first blowdown pipe 110, the first condensing assembly 120, the first water inlet pipe 121, the first water outlet pipe 122, the first condensing pipe 123, the first chamber 131, the second chamber 132;

[0027] The heat exchanger 200, the first air inlet pipe 210, the first valve 211, the first air outlet pipe 220, the second valve 221, the second blowdown pipe 230, the second condensing assembly 240, the second water inlet pipe 241, the second water outlet pipe 242, the second condensing pipe 243, the first partition 251, the second partition 252, the first area 261, the second area 262, the water inlet area 271, the water outlet area 272, the air blowing pipe 280;

[0028] The exhaust device 300, the annular partition 310, the annular area 311, the middle area 312, the second air inlet pipe 330, the second air outlet pipe 340, the third condensing assembly 350, the third water inlet pipe 351, the third water outlet pipe 352, the third condensing pipe 353, the filter assembly 360, the filter cotton 361, the air extractor 362, the oil return pipe 370;

[0029] The extruder 400, the vacuum pump 410. DETAILED DESCRIPTION

[0030] Embodiments of the present application are described below in detail, examples of which are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary, only for explaining the present application, and cannot be understood as limiting the present application.

[0031] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as limiting the present application.

[0032] In the description of the present application, the meaning of multiple is more than two, greater than, less than, more than, etc. is not included in the number, above, below, etc. is included in the number. If it is described that the first, the second is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the order of indicated technical features.

[0033] In the description of the present application, the words such as arrangement, installation, connection and the like should be understood in a broad sense, and the specific meanings of the words in the present application can be determined by the skilled in the art in combination with the specific content of the technical solutions, unless otherwise explicitly limited.

[0034] The embodiments of the present application are further described below with reference to the accompanying drawings.

[0035] According to some embodiments of the present application, referring to Figures 1 to 4 The extruder vacuum device comprises a sediment tank 100, a cold heat exchanger 200, a vacuum pump 410 and an exhaust device 300. The gas in the extruder 400 enters the sediment tank 100 through the connection between the gas inlet of the sediment tank 100 and the gas outlet of the extruder 400. The sediment tank 100 is provided with a first condensing assembly 120, which can condense the gas and precipitate the impurities carried by the gas. The cold heat exchanger 200 has two, and the gas inlet of the cold heat exchanger 200 is connected to the gas outlet of the sediment tank 100 through a first gas inlet pipe 210, which is provided with a first valve 211. The gas outlet of the cold heat exchanger 200 is connected to a first gas outlet pipe 220, which is provided with a second valve 221, and the cold heat exchanger 200 is provided with a second condensing assembly 240 for condensing the gas. The gas suction port of the vacuum pump 410 is connected to the first gas outlet pipe 220 of the two cold heat exchangers 200. The gas inlet of the exhaust device 300 is connected to the gas outlet of the vacuum pump 410, and the exhaust device 300 is provided with a third condensing assembly 350 for condensing the gas. The gas outlet of the exhaust device 300 is provided with a filtering assembly 360 for filtering the gas. When the vacuum pump 410 works, the vacuum pump 410 extracts the gas in the extruder 400, and the gas successively passes through the sediment tank 100, the cold heat exchanger 200 and the exhaust device 300 and is finally discharged.

[0036] It can be understood that when the first valve 211 and the second valve 221 on one cold heat exchanger 200 are both opened and the first valve 211 and the second valve 221 on the other cold heat exchanger 200 are both closed, the gas in the sediment tank 100 all enters one of the cold heat exchangers 200 for condensation. At this time, the other cold heat exchanger 200 can be cleaned and maintained, and the gas in the cold heat exchanger 200 is condensed and then enters the exhaust device 300 for further condensation, and then is discharged through the filtering assembly 360.

[0037] The sediment tank 100 of the extruder vacuum device can preliminarily precipitate the gas, reducing the possibility of the gas blocking the cold-heat exchanger 200. Moreover, when one of the cold-heat exchangers 200 needs to be cleaned, the other one can be simultaneously enabled without stopping the whole machine, thereby improving the working efficiency. The filtering assembly 360 can filter the gas to avoid pollution of the outside.

[0038] According to some embodiments of the present application, referring to Figure 2 , the bottom of the sediment tank 100 is connected with a first blowdown pipe 110, the first condensing assembly 120 comprises a first water inlet pipe 121, a first water outlet pipe 122 and a first condensing pipe 123, the first condensing pipe 123 is in a U shape, the two ends of the first condensing pipe 123 are respectively connected with the first water inlet pipe 121 and the first water outlet pipe 122, the first condensing pipe 123 is located in the sediment tank 100, the first condensing pipe 123 divides the inner cavity of the sediment tank 100 into a first chamber 131 and a second chamber 132, the first condensing pipe 123 has a certain gap with the bottom of the sediment tank 100 to make the first chamber 131 and the second chamber 132 communicate. The gas inlet of the sediment tank 100 communicates with the first chamber 131, and the gas outlet of the sediment tank 100 communicates with the second chamber 132.

[0039] It can be understood that the gas in the extruder 400 enters the first chamber 131 and contacts the surface of the first condensing pipe 123 and is condensed, and the liquid and solid impurities accumulate at the bottom of the sediment tank 100 under the action of gravity, the U-shaped first condensing pipe 123 can guide the gas to flow along the U shape, Figure 2 the arrow direction, i.e. the flow direction of the gas, so that the liquid and the fixed accumulate at the bottom of the sediment tank 100. After the gas enters the second chamber 132, it leaves the sediment tank 100 and enters the cold-heat exchanger 200. The cooperation of the first water inlet pipe 121 and the first water outlet pipe 122 makes the first condensing pipe 123 have flowing cold water inside to facilitate heat exchange with the gas.

[0040] According to some embodiments of the present application, referring to Figure 3 , the bottom of the cold-heat exchanger 200 is connected with a second blowdown pipe 230, the second condensing assembly 240 comprises a second water inlet pipe 241, a second water outlet pipe 242 and a plurality of second condensing pipes 243, the second condensing pipes 243 are located in the cold-heat exchanger 200, and the two ends of the second condensing pipes 243 are respectively connected with the second water inlet pipe 241 and the second water outlet pipe 242. The cooperation of the second water inlet pipe 241 and the second water outlet pipe 242 makes the second condensing pipes 243 have flowing cold water inside to facilitate heat exchange with the gas. The plurality of second condensing pipes 243 cooperatively increase the contact area with the gas to improve the condensing efficiency.

[0041] Preferably, referring to Figure 3The cold-heat exchanger 200 is provided with a first partition plate 251 and a second partition plate 252. The first partition plate 251 is horizontally arranged and separates the cold-heat exchanger 200 into a first area 261 and a second area 262. The first area 261 is above the second area 262. The second partition plate 252 is vertically arranged and separates the first area 261 into a water inlet area 271 and a water outlet area 272. The second condensing pipe 243 is located in the second area 262 and has a U shape to increase the contact area with the gas. The two ends of the second condensing pipe 243 are connected with the water inlet area 271 and the water outlet area 272, respectively. The first air inlet pipe 210 and the first air outlet pipe 220 are connected with the second area 262. It can be understood that the water in the second water inlet pipe 241 first enters the water inlet area 271 and is uniformly distributed in the water inlet area 271 and then enters the plurality of second condensing pipes 243, so as to avoid uneven distribution of the cold water in the plurality of second condensing pipes 243 and avoid that some of the second condensing pipes 243 do not have enough cold water. Preferably, the air inlet of the cold-heat exchanger 200 is lower than the air outlet of the cold-heat exchanger 200, so that the gas entering the cold-heat exchanger 200 flows from bottom to top and fully exchanges heat with the second condensing pipe 243.

[0042] Preferably, referring to Figure 3 The cold-heat exchanger 200 is connected with a blowing pipe 280. The blowing pipe 280 is connected with the second area 262. The connection end of the blowing pipe 280 with the cold-heat exchanger 200 is higher than the connection end of the first air inlet pipe 210 with the cold-heat exchanger 200. The blowing pipe 280 can blow and wash the oil stains attached to the inner wall of the second condensing pipe 243 and the cold-heat exchanger 200, so that the oil stains and other impurities flow downward and accumulate at the bottom of the cold-heat exchanger 200, so as to be discharged through the second blowdown pipe 230.

[0043] According to some embodiments of the present application, referring to Figure 1 and Figure 4The exhaust device 300 is provided with an annular partition plate 310, which divides the inner cavity of the exhaust device 300 into an annular region 311 and a middle region 312, and the annular region 311 surrounds the middle region 312. The exhaust device 300 is connected with a second air inlet pipe 330 and a second air outlet pipe 340, respectively, and the second air inlet pipe 330 and the second air outlet pipe 340 are both in communication with the middle region 312. The air outlet of the vacuum pump 410 is connected with the second air inlet pipe 330, the lower end of the second air outlet pipe 340 is connected with the top of the exhaust device 300, and a filtering assembly 360 is arranged in the second air outlet pipe 340. The third condensing assembly 350 comprises a third water inlet pipe 351, a third water outlet pipe 352 and a third condensing pipe 353, and the third condensing pipe 353 is located in the middle region 312. The third water inlet pipe 351 is connected with the annular region 311 and one end of the third condensing pipe 353, respectively, and the third water outlet pipe 352 is connected with the annular region 311 and the other end of the third condensing pipe 353, respectively.

[0044] It can be understood that the cooperation of the third water inlet pipe 351 and the third water outlet pipe 352 enables the third condensing pipe 353 and the annular region 311 to continuously have flowing cold water for heat exchange with the gas. After the gas enters the middle region 312 through the second air inlet pipe 330, the gas exchanges heat with the annular partition plate 310 and the third condensing pipe 353.

[0045] According to some embodiments of the present application, with reference to Figure 4 The filtering assembly 360 comprises filter cotton 361 and an air extractor 362, and the filter cotton 361 is located above the air extractor 362. The filter cotton 361 can filter impurities in the gas to avoid pollution of the outside environment. The air extractor 362 is used to extract the gas out of the exhaust device 300.

[0046] According to some embodiments of the present application, with reference to Figure 4 The exhaust device 300 is connected with an oil return pipe 370, which is connected with the middle region 312 and the vacuum pump 410, respectively. It can be understood that the gas coming out of the extruder 400 usually does not carry oil after being condensed by the sediment tank 100 and the heat exchanger 200. When the gas passes through the vacuum pump 410, oil leakage may occur due to the pumping of the vacuum pump 410, which causes the pump oil to flow with the gas. Therefore, the third condensing assembly 350 is needed to condense the gas again, and the oil obtained after condensation can be reused and returned to the vacuum pump 410, thereby avoiding the need to frequently add new pump oil, saving cost and improving efficiency.

[0047] In the description of the specification, reference to the description of the term "some embodiments" means that the specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. Descriptive or illustrative expressions in the specification do not necessarily refer to the same embodiment or example. Also, the specific feature, structure, material, or characteristic described can be combined in any suitable manner in one or more embodiments or examples.

[0048] Although embodiments of the application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and alterations can be made hereto without departing from the principles and the spirit of the application, the scope of which is defined by the claims and their equivalents.

Claims

1. An extruder vacuum apparatus characterized by, The utility model relates to a kind of vacuum exhaust systems, including: Precipitation tank (100), the air inlet of the precipitation tank (100) is connected with the air outlet of the extruder (400), first condensing assembly (120) is equipped in the precipitation tank (100), and the first condensing assembly (120) is used to condense gas and carry out precipitation to impurity of gas; Heat exchanger (200), the heat exchanger (200) has two, the air inlet of the heat exchanger (200) is connected with the air outlet of the precipitation tank (100) by first air inlet pipe (210), and first air inlet pipe (210) is equipped with first valve (211), the air outlet of the heat exchanger (200) is connected with first air outlet pipe (220), and first air outlet pipe (220) is equipped with second valve (221), and second condensing assembly (240) is equipped in the heat exchanger (200), and the second condensing assembly (240) is used to condense gas; Vacuum pump (410), the air outlet of the vacuum pump (410) is connected with the first air outlet pipe (220) of two heat exchangers (200) respectively; Exhaust device (300), the air inlet of the exhaust device (300) is connected with the air outlet of the vacuum pump (410), and third condensing assembly (350) is equipped in the exhaust device (300), and the third condensing assembly (350) is used to condense gas, and filter assembly (360) is equipped at the air outlet of the exhaust device (300), and the filter assembly (360) is used to filter gas; The bottom of the precipitation tank (100) is connected with first blowdown pipe (110), and first condensing assembly (120) includes first water inlet pipe (121), first water outlet pipe (122) and first condensing pipe (123), the first condensing pipe (123) is U-shaped, and the two ends of the first condensing pipe (123) are connected with the first water inlet pipe (121) and the first water outlet pipe (122) respectively, the first condensing pipe (123) is located in the precipitation tank (100), the first condensing pipe (123) separates the inner cavity of the precipitation tank (100) to form first chamber (131) and second chamber (132), and the first condensing pipe (123) has a gap with the bottom of the precipitation tank (100) so that the first chamber (131) and the second chamber (132) are communicated;The air inlet of the precipitation tank (100) is communicated with the first chamber (131), and the air outlet of the precipitation tank (100) is communicated with the second chamber (132).

2. The extruder vacuum apparatus of claim 1, wherein, The bottom of the heat exchanger (200) is connected with second blowdown pipe (230), and the second condensing assembly (240) includes second water inlet pipe (241), second water outlet pipe (242) and multiple second condensing pipes (243), the second condensing pipe (243) is located in the heat exchanger (200), and the two ends of the second condensing pipe (243) are connected with the second water inlet pipe (241) and the second water outlet pipe (242) respectively.

3. The extruder vacuum apparatus of claim 2, wherein, The cold heat exchanger (200) is provided with a first partition (251) and a second partition (252), the first partition (251) separates the cold heat exchanger (200) to form a first area (261) and a second area (262), the first area (261) is located above the second area (262), the second partition (252) separates the first area (261) to form a water inlet area (271) and a water outlet area (272), the second condensing pipe (243) is located in the second area (262), the second condensing pipe (243) is U-shaped, and the two ends of the second condensing pipe (243) are connected with the water inlet area (271) and the water outlet area (272) respectively, and the first air inlet pipe (210) and the first air outlet pipe (220) are connected with the second area (262) respectively.

4. The extruder vacuum apparatus of claim 3, wherein, The air inlet of the cold heat exchanger (200) is lower than the air outlet of the cold heat exchanger (200).

5. The extruder vacuum apparatus of claim 4, wherein, The cold heat exchanger (200) is connected with a blowing pipe (280), the blowing pipe (280) is connected with the second area (262), the connection end of the blowing pipe (280) with the cold heat exchanger (200) is higher than the connection end of the first air inlet pipe (210) with the cold heat exchanger (200), and the blowing pipe (280) is used for blowing and washing oil stains attached to the second condensing pipe (243) and the inner wall of the cold heat exchanger (200).

6. The extruder vacuum apparatus of claim 1, wherein, The exhaust device (300) is provided with an annular partition (310), the annular partition (310) separates the inner cavity of the exhaust device (300) to form an annular area (311) and a middle area (312), the exhaust device (300) is connected with a second air inlet pipe (330) and a second air outlet pipe (340) respectively, the second air inlet pipe (330) and the second air outlet pipe (340) are communicated with the middle area (312), the air outlet of the vacuum pump (410) is connected with the second air inlet pipe (330), the lower end of the second air outlet pipe (340) is connected with the top of the exhaust device (300), and the filter assembly (360) is arranged in the second air outlet pipe (340).

7. The extruder vacuum apparatus of claim 6, wherein, The third condensing assembly (350) comprises a third water inlet pipe (351), a third water outlet pipe (352) and a third condensing pipe (353), the third condensing pipe (353) is located in the middle area (312), the third water inlet pipe (351) is connected with the annular area (311) and one end of the third condensing pipe (353) respectively, and the third water outlet pipe (352) is connected with the annular area (311) and the other end of the third condensing pipe (353) respectively.

8. The extruder vacuum apparatus of claim 6, wherein, The filter assembly (360) comprises filter cotton (361) and an air extractor (362), the filter cotton (361) is located above the air extractor (362), and the air extractor (362) is used for extracting gas out of the exhaust device (300).

9. The extruder vacuum apparatus of claim 6, wherein, The exhaust device (300) is connected with an oil return pipe (370), and the oil return pipe (370) is connected with the middle part area (312) and the vacuum pump (410) respectively.

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