Vacuum exhaust system, vacuum pump cleaning method, and cleaning unit

Abstract

To provide a vacuum exhaust system, a vacuum pump cleaning method, and a cleaning unit that enable a vacuum pump to be easily restarted even when the vacuum pump stops in a state in which deposit constituting a by-product is fixed to a rotor or the like.SOLUTION: A vacuum exhaust system comprises: a vacuum pump 15 for exhausting process gas containing condensable gas or oxide dust; a cleaning solution storage tank 36 for storing cleaning solution for removing process gas deposit accumulated in a gas flow passage of the vacuum pump 15; a cleaning solution introduction pump 37 for introducing cleaning solution in the cleaning solution storage tank 36 into the gas flow passage from the exhaust side of the gas flow passage; and a vacuum pump 39 for drawing in and discharging the cleaning solution in the gas flow passage from the exhaust side of the gas flow passage.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vacuum pumping system, a method for cleaning a vacuum pump, and a cleaning unit. [Background technology]

[0002] For example, in semiconductor manufacturing processes, CVD (Chemical Vapor Deposition) and dry etching processes are performed to deposit semiconductor, insulator, metal films, etc. on semiconductor wafers using chemical vapor reactions, and various gases, such as silane (SiH4) gas, are used in the process chamber. The used gases exhausted from the process chamber are sucked by a vacuum pump such as a dry pump and further introduced into an abatement system via a gas exhaust pipe, where they are abatement-treated.

[0003] In such semiconductor manufacturing processes, when the used gases are cooled, by-products generated from the used gases solidify as films or powders and deposit on the exhaust piping, vacuum pumps, and abatement devices other than the process chamber, thereby requiring frequent maintenance.

[0004] As a normal maintenance procedure, cleaning gases such as CIF3 (chlorine trifluoride), NF3 (nitrogen trifluoride), and HCl (hydrogen chloride) are periodically introduced into the process chamber after each process step where a film is formed on a semiconductor wafer, depending on the type of product that adheres to the process chamber, to decompose and discharge the adhered material, thereby cleaning the reaction chamber, exhaust piping, vacuum pump, and detoxification device of the semiconductor processing equipment (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-143517 Summary of the Invention [Problem to be solved by the invention]

[0006] However, if a vacuum pump or the like stops with by-product deposits adhering to the rotor or the like, the deposits may harden and make it impossible to restart. In such cases, the conventional method requires disassembling and cleaning the vacuum pump, and replacing parts. Similar inspection work is also required when the pump stops due to a power outage or disaster.

[0007] Disassembling and cleaning the vacuum pump and replacing parts is not a problem if the working environment is in place, but if the working environment is not in place, workers will have to be dispatched from a distant location to carry out the work, or repairs will have to be outsourced, both of which create problems that disrupt production.

[0008] Therefore, a technical problem arises that must be solved in order to provide a vacuum exhaust system, a vacuum pump cleaning method, and a cleaning unit that can easily return the vacuum pump to a state where it can be restarted even if the vacuum pump stops with deposits stuck to the rotor, etc., and an object of the present invention is to solve this problem. [Means for solving the problem]

[0009] The present invention has been proposed to achieve the above-mentioned object, and the invention described in claim 1 provides a vacuum exhaust system comprising: a vacuum pump that exhausts a process gas containing condensable gas or oxidized dust; a cleaning liquid introduction section that introduces a cleaning liquid into the gas flow path of the vacuum pump to remove deposits of the process gas that have accumulated in the gas flow path; and a cleaning liquid removal pump that sucks and exhausts the cleaning liquid in the gas flow path from the exhaust side of the gas flow path.

[0010] According to this configuration, cleaning liquid is introduced into the gas flow path through the cleaning liquid inlet, and the introduced cleaning liquid can be used to clean process gas deposits that have accumulated inside the vacuum pump. After cleaning, the cleaning liquid containing the deposits can be sucked and discharged from the exhaust side of the gas flow path using a cleaning liquid removal pump, thereby removing the deposits and cleaning liquid from inside the vacuum pump. Furthermore, when the inside of the vacuum pump is cleaned using cleaning liquid, the deposits inside the vacuum pump are moistened with the cleaning liquid. Since cleaning and deposit removal are performed while the inside of the vacuum pump is moistened, the adhesion of process gas deposits that have adhered to rotors and other components inside the vacuum pump during the cleaning process is also loosened, allowing the rotors and other components to rotate. This allows the vacuum pump, which has been stopped due to adhered deposits, to be restarted, allowing the cleaning process to be performed efficiently while the vacuum pump is operating.

[0011] The invention described in claim 2 provides a vacuum exhaust system having the configuration described in claim 1, further comprising a cleaning liquid storage section for storing the cleaning liquid, and introducing the cleaning liquid in the cleaning liquid storage section into the gas flow path from the exhaust side of the gas flow path.

[0012] According to this configuration, the cleaning liquid is stored in the cleaning liquid storage section, and the cleaning liquid in the cleaning liquid storage section is introduced into the gas flow path from the exhaust side, and the introduced cleaning liquid can be used to clean and discharge process gas deposits that have accumulated in the gas flow path of the vacuum pump.

[0013] A third aspect of the present invention provides the vacuum pumping system of the first aspect, wherein the cleaning liquid is introduced from the intake side of the gas flow path by the cleaning liquid introduction part.

[0014] According to this configuration, the cleaning liquid is introduced into the gas flow path from the intake side, and the introduced cleaning liquid can be used to clean and discharge deposits of the process gas that have accumulated in the gas flow path of the vacuum pump.

[0015] The invention described in claim 4 is the vacuum pumping system described in claim 3, characterized in that, in the configuration described in claim 3, it further comprises a cleaning liquid storage section that stores the cleaning liquid, and the cleaning liquid in the cleaning liquid storage section is introduced into the gas flow path from the intake side of the gas flow path.

[0016] According to this configuration, the cleaning liquid stored in the cleaning liquid storage section is introduced into the gas flow path from the intake side, and the introduced cleaning liquid can be used to clean and discharge process gas deposits that have accumulated in the gas flow path of the vacuum pump.

[0017] The invention as set forth in claim 5 provides a vacuum pumping system as set forth in claim 1, wherein the cleaning liquid is water containing either microbubbles or ultrafine bubbles, or pure water.

[0018] According to this configuration, deposits inside the vacuum pump can be removed easily and cleanly using a cleaning liquid that is water containing either microbubbles or ultrafine bubbles, or pure water.

[0019] A sixth aspect of the present invention provides the vacuum pumping system of the first aspect, wherein the cleaning liquid is an acidic or alkaline cleaning liquid.

[0020] According to this configuration, deposits inside the vacuum pump can be removed easily and cleanly using an acidic or alkaline cleaning liquid.

[0021] The invention described in claim 7 provides a vacuum exhaust system having the configuration described in claim 1, further comprising an inert gas introduction unit that introduces an inert gas into an oil box that houses a drive unit and a bearing unit of the vacuum pump, and creates a positive pressure inside the oil box through the gas flow path.

[0022] With this configuration, when cleaning liquid is introduced into the gas flow path to perform cleaning processing, the inert gas introduced into the oil box prevents the cleaning liquid introduced into the gas flow path from penetrating into the oil box, thereby preventing the drive unit, bearings, etc. inside the oil box from being contaminated with cleaning liquid or deposits during cleaning processing.

[0023] An eighth aspect of the present invention provides a vacuum evacuation system according to the first aspect, wherein the vacuum pump is a positive displacement vacuum pump.

[0024] This configuration can be applied to a vacuum pumping system that cleans the inside of a positive displacement vacuum pump.

[0025] The invention described in claim 9 provides a method for cleaning a vacuum pump that discharges a process gas containing a condensable gas or oxide dust, comprising the steps of: introducing a cleaning liquid into a gas flow path of the vacuum pump, the cleaning liquid being configured to remove deposits of the process gas that have accumulated in the gas flow path; sucking and discharging the cleaning liquid in the gas flow path from the exhaust side of the gas flow path using a cleaning liquid removal pump; and drying the gas flow path.

[0026] According to this method, by carrying out the step of introducing a cleaning liquid into the gas flow path of the vacuum pump, it is possible to clean the process gas deposits that have accumulated inside the vacuum pump. Furthermore, by carrying out the step of sucking and discharging the cleaning liquid containing the deposits from the exhaust side of the gas flow path after cleaning using a cleaning liquid removal pump, it is possible to smoothly discharge and remove the deposits and cleaning liquid outside the vacuum pump. Furthermore, by carrying out the step of drying the gas flow path after discharging and removing the cleaning liquid containing the deposits, it is possible to dry the inside of the gas flow path.

[0027] The invention described in claim 10 provides a method for cleaning a vacuum pump according to claim 9, further comprising the step of introducing an inert gas into an oil box that houses a drive unit and a bearing unit of the vacuum pump, and creating a positive pressure in the oil box from the gas flow path, before the step of introducing the cleaning liquid into the gas flow path.

[0028] According to this method, when a cleaning solution is introduced into the gas flow path to perform cleaning, the inert gas introduced into the oil box prevents the cleaning solution introduced into the gas flow path from penetrating into the oil box, thereby preventing the drive unit, bearings, etc. inside the oil box from being contaminated with the cleaning solution or deposits during cleaning.

[0029] The invention described in claim 11 provides a method for cleaning a vacuum pump, the method described in claim 9 further including a step of driving the vacuum pump between the step of introducing the cleaning liquid into the gas flow path and the step of discharging the cleaning liquid from the gas flow path.

[0030] According to this method, after the step of introducing the cleaning liquid into the gas flow path of the vacuum pump is performed, the step of driving the vacuum pump is subsequently performed, so that the vacuum pump is driven with the cleaning liquid in the gas flow path, and this driving can actively remove the deposits while stirring the cleaning liquid. Next, the step of sucking and discharging the cleaning liquid containing the deposits from the exhaust side of the gas flow path is performed, and the actively removed deposits and cleaning liquid can be discharged outside the vacuum pump.

[0031] The invention described in claim 12 provides a method for cleaning a vacuum pump, the method described in claim 9 further including a step of driving the vacuum pump between the step of discharging the cleaning liquid from the gas flow path and the step of drying the gas flow path.

[0032] According to this method, after performing the step of sucking and discharging the cleaning liquid containing deposits from the exhaust side of the gas flow path, and before performing the step of drying the gas flow path, the step of operating the vacuum pump is performed, so that the gas flow path can be dried after confirming that the deposits have been removed and that the vacuum pump can actually be operated. Therefore, it is possible to eliminate the wasted time of drying the gas flow path when the vacuum pump is not ready to be operated, and to shorten the processing time.

[0033] The invention described in claim 13 provides a cleaning unit for cleaning a gas flow path of a vacuum pump that discharges a process gas containing a condensable gas or oxidized dust, the cleaning unit comprising: a cleaning liquid inlet portion that introduces a cleaning liquid into the gas flow path to remove deposits of the process gas that have accumulated in the gas flow path; and a cleaning liquid removal pump that sucks and discharges the cleaning liquid in the gas flow path from the exhaust side of the gas flow path.

[0034] With this configuration, the cleaning liquid storage tank, cleaning liquid introduction pump, and cleaning liquid removal pump are integrated into a cleaning unit, which can be easily transported to a location where it is needed and the required cleaning process can be performed.

[0035] The invention described in claim 14 provides a cleaning unit having the configuration described in claim 13, further comprising a cleaning liquid storage section for storing the cleaning liquid, and the cleaning liquid storage section, the cleaning liquid introduction section and the cleaning liquid removal pump are mounted on a portable cart.

[0036] With this configuration, a cleaning unit equipped with a cleaning liquid storage section, a cleaning liquid introduction section, and a cleaning liquid removal pump mounted on a portable cart can be transported to the required location and the required cleaning process can be easily performed. [Effects of the Invention]

[0037] According to the present invention, a cleaning liquid is introduced into the gas flow path from the cleaning liquid inlet, and the introduced cleaning liquid can be used to clean process gas deposits that have accumulated inside the vacuum pump, so that deposits that have accumulated inside the gas passage can be easily removed and discharged to the outside.

[0038] Furthermore, since the deposits inside the vacuum pump are cleaned and removed while wet with the cleaning liquid, the adhesion of process gas deposits adhering to rotors and other components inside the vacuum pump is loosened, allowing the rotors and other components to rotate, and the deposits are also cleaned and removed. Furthermore, since the rotors and other components that had been stopped due to the adhering deposits are now able to rotate, the vacuum pump can be easily restarted and the cleaning process can be carried out efficiently while the vacuum pump is running. This makes the cleaning process easier and cleaner. [Brief explanation of the drawings]

[0039] [Figure 1] 1 is a diagram showing a schematic overall configuration of an exhaust gas treatment device in a semiconductor manufacturing process to which a vacuum exhaust system shown as an example according to an embodiment of the present invention is applied; [Figure 2] 3 is a schematic side cross-sectional view showing the internal structure of a vacuum pump in the exhaust gas treatment device together with an inert gas introduction unit. FIG. [Figure 3] FIG. 2 is a diagram showing the overall configuration of the vacuum evacuation system according to the first embodiment, together with a vacuum pump and other components. [Figure 4] FIG. 2 is a diagram showing a schematic overall configuration of the vacuum exhaust system according to a second embodiment of the present invention, together with a vacuum pump and other components. [Figure 5] 5 is a cross-sectional view schematically showing a mechanical booster pump used in the second embodiment shown in FIG. 4 and an example of a structure for supplying a cleaning liquid to the mechanical booster pump. FIG. [Figure 6] FIG. 10 is a diagram showing a schematic overall configuration of a third embodiment of the vacuum exhaust system, together with a vacuum pump and the like. [Figure 7]FIG. 10 is a diagram showing a schematic overall configuration of a fourth embodiment of the vacuum exhaust system, together with a vacuum pump and the like. [Figure 8] FIG. 10 is a diagram showing a schematic overall configuration of the vacuum exhaust system according to a fifth embodiment of the present invention, together with a vacuum pump and the like. DETAILED DESCRIPTION OF THE INVENTION

[0040] To achieve the object of the present invention to provide a vacuum exhaust system, a vacuum pump cleaning method, and a cleaning unit that can easily return a vacuum pump to a state where it can be restarted even if the vacuum pump stops with by-product deposits stuck to the rotor or the like, the present invention has been realized by providing a configuration that includes a vacuum pump that exhausts process gas containing condensable gases or oxidized dust, a cleaning liquid introduction section that introduces a cleaning liquid into the gas flow path of the vacuum pump to remove deposits of the process gas that have accumulated in the gas flow path, and a cleaning liquid removal pump that sucks in and discharges the cleaning liquid in the gas flow path from the exhaust side of the gas flow path. [Example]

[0041] An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. In the following embodiment, when the number, value, amount, range, etc. of components is mentioned, the number is not limited to the specific number, and may be more or less than the specific number, unless otherwise specified or when it is clearly limited to a specific number in principle.

[0042] Furthermore, when referring to the shape or positional relationship of components, etc., it includes things that are substantially similar or approximate to those shapes, etc., unless otherwise specified or when it is clearly considered otherwise in principle.

[0043] In addition, in cross-sectional views, hatching of some components may be omitted in order to make the cross-sectional structure of the components easier to understand.

[0044] In the following description, expressions indicating directions such as up, down, left, and right are not absolute and are appropriate when each part of the vacuum exhaust system of the present invention is in the position shown, but if the position changes, they should be interpreted accordingly. Furthermore, the same elements are given the same symbols throughout the description of the embodiments.

[0045] <First Example> 1 to 3 show a vacuum exhaust system as an example according to an embodiment of the present invention, in which FIG. 1 is a schematic diagram showing the overall configuration of an exhaust gas treatment device to which the vacuum exhaust system is applied, FIG. 2 is a schematic side cross-sectional view showing the internal structure of a vacuum pump 15 in the exhaust gas treatment device together with an inert gas introduction unit 50, and FIG. 3 is a schematic diagram showing the overall configuration of a first example of the vacuum exhaust system together with the vacuum pump 15, etc.

[0046] First, the overall schematic configuration of the exhaust gas treatment device will be described mainly with reference to FIG. 1. The internal structure of vacuum pump 15 will also be described with reference to FIG. 2. As shown in FIG. 1, the exhaust gas treatment device is controlled by a predetermined procedure executed by a program in control device 10. A semiconductor wafer 12 is housed inside process chamber 11, to which a process gas for processing and a cleaning gas for cleaning are supplied via gas supply piping 13. Furthermore, vacuum pump 15 is connected to process chamber 11 via gas piping 14. Gas piping 14 and gas inlet 15a of vacuum pump 15 are detachably connected. The vacuum pump 15 used here is a dry pump that does not use oil in parts that come into contact with gas. The process chamber 11 is depressurized to a high vacuum by driving vacuum pump 15.

[0047] That is, the process gases containing condensable gases or oxide dusts that have been treated inside the process chamber 11, such as process gases such as silane (SiH4) gas and cleaning gases such as ClF3 (chlorine trifluoride), NF3 (nitrogen trifluoride), and HCl (hydrogen chloride) (hereinafter, these process gases and cleaning gases are collectively referred to as "used gas G1"), are introduced into the downstream vacuum pump 15 through gas piping 14, which serves as a gas passage. If it is necessary to dramatically increase the pumping speed, a mechanical booster pump 16 may be provided between the process chamber 11 and the vacuum pump 15.

[0048] The internal structure of the vacuum pump 15 is shown in Figure 2. In the vacuum pump 15, used gas G1 from the process chamber 11 is sucked into the interior of the vacuum pump 15 through a gas inlet 15a, and the used gas G1 is gradually pressurized in six stages within the vacuum pump 15, that is, by passing the used gas G1 through a first-stage pump chamber 17a, a second-stage pump chamber 17b, a third-stage pump chamber 17c, a fourth-stage pump chamber 17d, a fifth-stage pump chamber 17e, and a sixth-stage pump chamber 17f in that order. If a mechanical booster pump 16 is provided between the process chamber 11 and the vacuum pump 15, the used gas G1 from the process chamber 11 passes through the mechanical booster pump 16 before being introduced into the vacuum pump 15.

[0049] 1, the used gas G1 pressurized to near atmospheric pressure in the vacuum pump 15 is discharged from the gas exhaust port 15b into the gas exhaust pipe 18, sent from the gas exhaust pipe 18 to the detoxification device 19, and discharged into the atmosphere after being rendered harmless by the detoxification device 19. Therefore, one end of the gas exhaust pipe 18 is connected to the gas exhaust port 15b of the vacuum pump 15, and the other end is connected to the gas inlet port 19a of the detoxification device 19.

[0050] Next, the internal structure of the vacuum pump 15 will be further explained using Figure 2. The vacuum pump 15 shown in Figure 2 is a positive displacement vacuum pump. The vacuum pump 15 comprises a pump casing 20 having a plurality of pump chambers (six in this embodiment), namely a first stage pump chamber 17a, a second stage pump chamber 17b, a third stage pump chamber 17c, a fourth stage pump chamber 17d, a fifth stage pump chamber 17e, and a sixth stage pump chamber 17f, rotors 21a, 21b, 21c, 21d, 21e, and 21f respectively disposed in the pump chambers 17a to 17f, and rotors 21a to 21f integrally formed. The pump casing 20 includes a pair of fixedly mounted rotating shafts 22a, 22b that rotate the rotors 21a to 21f integrally, a pair of gears 47a, 47b that rotate the pair of rotating shafts 22a, 22b synchronously, a motor 24 as a rotation drive mechanism for rotating the rotating shafts 22a, 22b via the pair of gears 47a, 47b, and bearings 25a, 25a, 26b, 26b that support the rotating shafts 22a, 22b, respectively, on the pump casing 20.

[0051] The pump casing 20 has a first exterior part 23a, a second exterior part 23b attached to the gas inlet 15a side of the first exterior part 23a, and a third exterior part 23c attached to the gas outlet 15b side of the first exterior part 23a, and the first exterior part 23a, second exterior part 23b, and third exterior part 23c are connected to each other to form a single casing.

[0052] Although not shown, first exterior part 23a is formed by stacking a plurality of stators in the axial direction in order to facilitate assembly, and pump chambers 17a-17f are provided inside first exterior part 23a. Rotors 21a-21f are disposed inside pump chambers 17a-17f, and gas inlet 15a and gas outlet 15b are provided on the outer surface of first exterior part 23a, communicating from the inside to the outer surface.

[0053] The second exterior part 23b has an oil box 27 formed therein. The oil box 27 has a bearing box 27a that houses bearings 25a and 25b as bearing parts and an oil box 27b that houses gears (not shown) as driven parts. The third exterior part 23c has an oil box 28 that houses a bearing box 28a that houses bearings 26a and 26b as bearing parts and an oil box 28b that houses gears 47a and 47b as driving parts, and a motor space 48 that houses the motor 24. The second exterior part 23b and the third exterior part 23c each have an inert gas inlet 30 for introducing inert gas. An inert gas introduction unit 50 (described later) is attached to the inert gas inlet 30. Then, inert gas is introduced into the oil boxes 27 and 28 from the inert gas introduction unit 50, and the pressure inside the oil boxes 27 and 28 is maintained to be more positive than the pressure inside the gas flow path that leads from the gas inlet 15a through the pump chambers 17a to 17f, etc. to the gas outlet 15b. Note that the inert gas introduction port 30 is closed when the inert gas introduction unit 50 is not installed.

[0054] Next, the operation of the exhaust gas treatment device configured as above will be described. First, when vacuum pump 15 is operated in response to a start command from control device 10, motor 24 is also driven, and rotating shaft 22a is rotated by the driving force of motor 24. At this time, rotating shaft 22b, which is arranged parallel to rotating shaft 22a, rotates synchronously due to the meshing of gears 47a and 47b, and rotating shaft 22b rotates in the opposite direction to rotating shaft 22a.

[0055] Furthermore, due to the rotation of the rotary shafts 22a and 22b, the rotors 21a to 21f fixed integrally to the rotary shaft 22a and the rotors 21a to 21f fixed integrally to the rotary shaft 22b rotate in opposite directions relative to each other within the pump chambers 17a to 17f. Although not shown, the rotors 21a to 21f attached to the rotary shafts 22a and 22b in this embodiment are cocoon-shaped Roots rotors, which rotate synchronously with a phase difference of 90° while maintaining a small gap between them without contacting each other.

[0056] As the rotors 21a to 21f rotate, the used gas G1 is sucked into the first-stage pump chamber 17a through the gas inlet 15a, which is connected to the vacuum target space. The used gas G1 is then sucked from the first-stage pump chamber 17a to the second-stage pump chamber 17b, the third-stage pump chamber 17c, the fourth-stage pump chamber 17d, the fifth-stage pump chamber 17e, and the sixth-stage pump chamber 17f in that order. Finally, the used gas G1 is exhausted from the vacuum pump 15 through the gas exhaust pipe 18, which is connected to the gas outlet 15b of the sixth-stage pump chamber 17f, and the vacuum target space is brought into a vacuum state.

[0057] At this time, the used gas G1 is compressed in each of the pump chambers 17a, 17b, 17c, 17d, 17e, and 17f while being discharged, and as a result, the temperature of the used gas G1 rises, and the temperature inside the first exterior part 23a of the pump casing 20 also rises. Among the pump chambers 17a, 17b, 17c, 17d, 17e, and 17f, the temperature of the used gas G1 on the discharge side of the sixth-stage pump chamber 17f, which has the largest difference in pressure of the used gas G1 between the suction side and the discharge side, is the highest. The temperature of the used gas G1 here is, for example, about 150 to 200°C.

[0058] Furthermore, the used gas G1 discharged from the sixth stage pump chamber 17f through the gas discharge port 15b further passes through the gas discharge pipe 18 and heads toward the detoxification device 19 located several meters away.

[0059] In the vacuum pump 15 shown in this embodiment, gas remaining inside the vacuum pump 15 solidifies as a film or powder, forming deposits (mainly silica SiO2). These deposits adhere to the interior of the dry pump within a short period (two to three months), causing operational problems. Furthermore, if the dry pump 17 is temporarily stopped for maintenance or other reasons, the rotors 21a-21f may lock, making it impossible to restart. This is because the gaps between the rotors 21a-21f and the inner walls of the pump chambers 17a-17f (the fixed side) are designed to widen on one side (the left side) and narrow on the other side (the right side) when the pump is stopped. When the pump is stopped, the narrowest gap is approximately several tens to several hundreds of micrometers.

[0060] Therefore, in this embodiment, when the vacuum pump 15 is stopped and an attempt is made to restart it, if the gap between the rotors 21a to 21f and the inner wall surface of the pump chambers 17a to 17f (particularly the gap on the side designed to be narrow) becomes clogged with deposits and the rotors 21a to 21f become locked, a vacuum exhaust system is provided that can easily remove the deposits and the like that have accumulated inside the exhaust gas treatment device and restart the device.

[0061] In the vacuum exhaust system shown in FIG. 3, a cleaning unit 31 and an inert gas introduction unit 50 are attached to the vacuum pump 15, a cleaning liquid is introduced into the gas flow path of the vacuum pump 15 from the gas outlet 15b side, the inside of the gas flow path is cleaned with the introduced cleaning liquid, and the deposits inside the vacuum pump 15 that have been removed by cleaning are discharged outside the vacuum pump 15 together with the cleaning liquid.

[0062] As shown in FIGS. 1 to 3 , the inert gas introduction unit 50 includes an inert gas supply tank 51, an inert gas supply pipe 52, and an on-off adjustment valve 53 provided midway along the inert gas supply pipe 52. The inert gas used here is, for example, N2 (nitrogen) purge gas. When introducing a cleaning liquid into the gas flow path of the vacuum pump 15 for cleaning, the inert gas introduction unit 50 is attached such that the ends of the inert gas supply pipes 52 are connected to the inert gas inlets 30 of the oil boxes 27 and 28. The inert gas in the inert gas supply tank 51 is sent through the inert gas supply pipes 52 into the oil boxes 27 and 28, respectively, to make the pressure in the oil boxes 27 and 28 higher than the pressure in the gas flow path, thereby preventing the cleaning liquid from penetrating into the oil boxes 27 and 28. The pressure of the inert gas introduced into the oil boxes 27 and 28 is adjusted by the on-off adjustment valve 53.

[0063] 1 and 3, the cleaning unit 31 includes a three-way valve 35, a cleaning liquid storage tank 36, a cleaning liquid introduction pump 37, a vacuum container 38, a vacuum pump 39, a control unit 32A, etc. The cleaning unit 31 and the inert gas introduction unit 50 are usually integrated and can be placed on a portable cart 45 shown in FIG. 1, for example, and moved together with the cart 45 to a position close to the vacuum pump 15 that needs to be cleaned. The control unit 32 also includes a microcomputer with an embedded program that can control the cleaning unit 31 and the inert gas introduction unit 50 in accordance with predetermined procedures.

[0064] The three-way valve 35 is a valve having three ports: a first port 35a, a second port 35b, and a third port 35c. One end of a water supply / drainage pipe 40 is connected to the first port 35a, one end of a water supply pipe 41 is connected to the second port 35b, and one end of a drainage pipe 42 is connected to the third port 35c.

[0065] The other end of the water supply and drainage pipe 40 is detachably attached to the gas exhaust port 15b of the vacuum pump 15. When connected to the gas exhaust port 15b, the connection is tightly secured so that no water leaks from between the gas exhaust port 15b and the pipe.

[0066] The other end of the water supply pipe 41 is connected to the cleaning liquid storage tank 36 via the cleaning liquid introduction pump 37 and the on-off valve 34. When the cleaning liquid introduction pump 37 is driven with the on-off valve 34 open, the cleaning liquid stored in the cleaning liquid storage tank 36 can be supplied to the water supply and drainage pipe 40 through the second port 35b and the first port 35a of the three-way valve 35.

[0067] The other end of the drainage pipe 42 is connected to the cleaning liquid storage tank 36, which serves as a cleaning liquid storage section, via the vacuum container 38, an adjustment on-off valve 49, and a vacuum pump 39. When the second port 35b of the three-way valve 35 is closed and the first port 35a and the third port 35c are opened, the drainage pipe 42 can draw the cleaning liquid introduced into the vacuum pump 15 through the water supply and drainage pipe 40 through the drainage pipe 42, the vacuum container 38, and the vacuum pump 39, and return the drawn cleaning liquid to the cleaning liquid storage tank 36.

[0068] One end of an air suction pipe 43 is connected to the vacuum container 38 via an on-off adjustment valve 44. The other end of the air suction pipe 43 is detachably attached to the gas inlet 15a of the vacuum pump 15. When connected to the gas inlet 15a, the air suction pipe 43 is tightly connected to the gas inlet 15a to prevent air leakage. The air suction pipe 43 is used to draw air from the vacuum pump 15 through the gas inlet 15a side and draw the cleaning liquid from the gas outlet 15b side into the vacuum pump 15 when the cleaning liquid in the cleaning liquid storage tank 36 is sent into the vacuum pump 15 through the water supply pipe 41, the second port 35b, and the water supply and drainage pipe 40.

[0069] The cleaning liquid storage tank 36 is a tank for storing the cleaning liquid. The cleaning liquid may be water or pure water containing either microbubbles (bubbles with diameters of less than 100 μm but not less than 1 μm) or ultrafine bubbles (bubbles with diameters less than 1 μm). The microbubbles or ultrafine bubbles may be formed on the way from the cleaning liquid storage tank 36 to the vacuum pump 15. The reason for using such a cleaning liquid is that it is easy to handle and that the cleaning liquid storage tank 36, water supply piping 41, and other equipment can be constructed without using special or expensive materials, taking into account corrosion resistance. Depending on the composition of the deposits, an acidic or alkaline cleaning liquid may also be used. Using such a cleaning liquid can promote the dissolution of deposits through a chemical reaction and neutralize the solution of the dissolved deposits.

[0070] Next, an example of a procedure for performing a cleaning process using the cleaning unit 31 and the inert gas introduction unit 50 to restart the vacuum pump 15 when the vacuum pump 15 has been locked and stopped due to deposits inside the vacuum pump 15 will be described in the order of steps (1) to (13).

[0071] (1) First, the portable cart 45 carrying the cleaning unit 31, the inert gas introduction unit 50, etc. is transported near the vacuum pump 15 that needs to be cleaned.

[0072] (2) Next, the gas exhaust pipe 18 and the gas pipe 14 are removed from the vacuum pump 15.

[0073] (3) Next, the air suction pipe 43 of the cleaning unit 31 is connected to the gas inlet 15a of the vacuum pump 15, and the water supply / drainage pipe 40 of the cleaning unit 31 is connected to the gas outlet 15b of the vacuum pump 15. In this state, the first port 35a and the second port 35b of the three-way valve 35 are open, and the third port 35c is closed, and the operation of the cleaning unit 31 is also stopped.

[0074] (4) Next, the inert gas supply pipe 52 is connected to the inert gas inlet 30 on the oil box 27 side of the vacuum pump 15 and the inert gas inlet 30 on the oil box 28 side. In this state, the on / off adjustment valve 53 of the inert gas introduction unit 50 is closed. This completes preparations for cleaning the vacuum pump 15 using the cleaning unit 31 and the inert gas introduction unit 50. Next, the cleaning operation of the vacuum pump 15 begins.

[0075] (5) The cleaning operation of the vacuum pump 15 is performed according to a predetermined procedure under the control of the control unit 32. First, the on-off adjustment valve 53 of the inert gas introduction unit 50 is opened, and inert gas is introduced from the inert gas supply tank 51 through the inert gas supply pipe 52 into the oil box 27 and the oil box 28. Then, by introducing the inert gas, the pressure inside the oil box 27 and the pressure inside the oil box 28 are made to be positive relative to the pressure inside the gas flow path. After this state is achieved, the on-off valve 34 is opened, and the cleaning liquid introduction pump 37 of the cleaning unit 31 is operated.

[0076] (6) When the cleaning liquid introduction pump 37 starts operating, the cleaning liquid in the cleaning liquid storage tank 36 is introduced into the gas flow path of the vacuum pump 15 from the gas exhaust port 15b through the water supply pipe 41, the second port 35b, the first port 35a, and the water supply and drainage pipe 40.

[0077] (7) In addition, as the cleaning liquid is introduced into the gas flow path, the on / off adjustment valve 44 of the air suction pipe 43 is opened, and air is suctioned from the gas inlet 15a side, facilitating the introduction of the cleaning liquid flowing into the gas flow path from the gas outlet 15b. Note that this air suction may be omitted if the cleaning liquid can be easily introduced into the gas flow path.

[0078] (8) Furthermore, as the cleaning liquid is introduced into the gas flow path, the opening amount of the on-off adjustment valve 53 in the inert gas introduction unit 50 is adjusted. Then, the pressure inside the oil box 27 and the pressure inside the oil box 28 are each maintained at a positive pressure higher than the pressure inside the gas flow path, thereby preventing the cleaning liquid introduced into the gas flow path from seeping into the oil box 27 and the oil box 28. Then, when a predetermined amount of cleaning liquid has been introduced into the gas flow path, the control unit 32 stops the cleaning liquid introduction pump 37 and closes the on-off valve 34, the second port 35b, the first port 35a, and the on-off adjustment valve 44. At this time, the rotors 21a to 21f and the inside of the pump casing 20 are immersed to some extent in the cleaning liquid.

[0079] (9) Next, the worker manually rotates the rotating shafts 22a and 22b together with the rotors 21a to 21f. When the deposits accumulated inside the pump casing 20 are softened and dissolved by the immersion in the cleaning liquid, the rotating shafts 22a and 22b can be easily rotated together with the rotors 21a to 21f. This rotation also removes deposits that have adhered to the inner surface of the pump casing 20 and the surfaces of the rotors 21a to 21f.

[0080] (10) When the deposits adhering to the inner surface of the pump casing 20 and the surfaces of the rotors 21a to 21f soften and dissolve in the cleaning liquid, the first port 35a and the third port 35c of the three-way valve 35 are opened, and the vacuum pump 39 is operated. At the same time, the intake valve 46 and the on-off adjustment valve 44, which are connected to the vacuum container 38, are opened. When the vacuum pump 39 is operated, the cleaning liquid introduced into the gas flow path, together with the deposits, is returned to the cleaning liquid storage tank 36 through the water supply and drainage piping 40, the first port 35a, the third port 35c, the drainage piping 42, and the vacuum pump 39. Whether the deposits in the vacuum pump have been properly removed in the steps up to this point may be determined by manually rotating the rotating shafts 22a and 22b together with the rotors 21a to 21f and determining whether the torque generated when manually rotating the shafts is equal to or less than a predetermined value. Furthermore, in step (9), if the operator determines that the rotors 21a to 21f as well as the rotary shafts 22a and 22b cannot be rotated normally manually, the operations from step (5) to step (10) are repeated.

[0081] (11) After the cleaning liquid is removed from the gas flow path, the vacuum pump 39 is left in an idle state for a while. During this idle operation, the intake valve 46 and the on-off adjustment valve 44 are opened, allowing outside air to be drawn in through the gas inlet 15a of the vacuum pump 15. The outside air drawn into the vacuum pump 15 then passes through the gas flow path and is discharged through the gas outlet 15b of the vacuum pump 15. The air then flows through the water supply and drainage piping 40, the first port 35a, the third port 35c, the drainage piping 42, and the vacuum pump 39, drying the inside of the gas flow path. This drying operation takes approximately two hours. During the drying operation, the control unit 32 controls the inert gas introduction unit 50 to flow into the oil boxes 27 and 28, thereby drying the insides of the oil boxes 27 and 28.

[0082] (12) Note that between the step of discharging the cleaning liquid from the gas flow path and the step of drying the gas flow path, a step may be interposed in which an operator manually rotates the rotating shafts 22a and 22b together with the rotors 21a to 21f to drive the vacuum pump 15.

[0083] (13) Furthermore, when the cleaning and drying operations of the vacuum pump 15 are completed, the control unit 32 closes the on / off adjustment valve 53 of the inert gas introduction unit 50 and stops the introduction of the inert gas into the oil box 27 and the oil box 28. Thereafter, the inert gas supply piping 52 is removed from the vacuum pump 15. Next, the water supply and drainage piping 40 is removed from the gas exhaust port 15b of the vacuum pump 15, and the air suction piping 43 is removed from the gas inlet 15a of the vacuum pump 15. This allows the cleaning unit 31 and the inert gas introduction unit 50 to be separated from the vacuum pump 15. Then, after the cleaning is completed, the gas piping 14 is connected to the gas inlet 15a of the vacuum pump 15 from which the cleaning unit 31 and the inert gas introduction unit 50 have been separated, and the gas exhaust piping 18 is connected to the gas exhaust port 15b, thereby returning the exhaust gas treatment device shown in FIG.

[0084] Therefore, with the vacuum pumping system according to this embodiment, the cleaning liquid stored in the cleaning liquid storage tank 36 is introduced into the gas flow path of the vacuum pump 15 from the gas outlet 15b side, and the introduced cleaning liquid is used to clean deposits that have accumulated in the vacuum pump 15 due to the passage of the process gas (used gas G1). After cleaning, the cleaning liquid containing the deposits is sucked and discharged from the gas outlet 15b side of the gas flow path using the vacuum pump 39, which serves as a cleaning liquid removal pump. The deposits and cleaning liquid are then discharged and removed from the vacuum pump 15. Furthermore, cleaning with the cleaning liquid wets the deposits in the vacuum pump 15, and cleaning is performed in this wet state. Therefore, the adhesion of process gas deposits adhering to the rotors 21a-21f, etc., within the vacuum pump 15 during the cleaning process is also dissolved and loosened by the cleaning liquid, allowing the rotors 21a-21f to rotate. This allows the vacuum pump 15, which has been stopped due to adhering deposits, to be easily restarted and the cleaning process can be performed.

[0085] In addition, in this embodiment, the application to cleaning of the vacuum pump 15 that cannot be restarted after being stopped has been described, but it is also possible to apply this to periodic maintenance to prevent the vacuum pump 15 from becoming unable to be restarted due to deposits.

[0086] Although the present embodiment has been described as being applied to cleaning the vacuum pump 15, it is also possible to apply the present invention to cleaning the mechanical booster pump 16.

[0087] In addition, in this embodiment, the cleaning liquid stored in the cleaning liquid storage tank 36 as a cleaning liquid storage section is described as being used by circulating it, but if it is desired to use a cleaning liquid that is different from the cleaning liquid stored in the cleaning liquid storage tank 36, for example a high-quality cleaning liquid, it is also possible to prepare a water tank 33 as a cleaning liquid storage section that stores high-quality cleaning liquid separately from the cleaning liquid storage tank 36 and use the cleaning liquid in the water tank 33. Reference numeral 34 denotes an on-off valve controlled by the control section 32, and by switching the on-off valve 34 on or off, it is possible to select whether to use the cleaning liquid in the cleaning liquid storage tank 36 or the cleaning liquid in the water tank 33.

[0088] <Second Example> FIG. 4 shows a second embodiment of the vacuum evacuation system, and is a configuration diagram showing the overall schematic configuration of the system in the second embodiment together with a vacuum pump 15 and other components. The second embodiment shown in FIG. 4 is a partial modification of the configuration of the first embodiment shown in FIG. 3. Therefore, the same components as those in FIG. 3 are given the same reference numerals, and redundant explanations will be omitted, and the following description will mainly focus on the differences from the embodiment shown in FIG. 3. In the following description, members that are given the same reference numerals as those in FIGS. 1 to 3 are the same as or equivalent to the members shown in FIGS. 1 to 3.

[0089] The difference between the second embodiment shown in FIG. 4 and the first embodiment shown in FIG. 3 is that in the first embodiment, the cleaning liquid stored in the cleaning liquid storage tank 36 or the cleaning liquid stored in the water tank 33 is flowed into the vacuum pump 15 from the gas outlet 15b side of the vacuum pump 15, and only the vacuum pump 15 is cleaned, whereas in the second embodiment, a regular water faucet is used as the cleaning liquid storage section, the water supply pipe 41A is connected to the regular water faucet, and regular tap water is used as the cleaning liquid, and also, during cleaning, both the mechanical booster pump 16 and the vacuum pump 15 can be cleaned.

[0090] 4, a mechanical booster pump 16 is provided in the middle of a gas pipe 14 connecting a process chamber 11 and a vacuum pump 15. That is, the gas pipe 14 is connected to a gas inlet 16a and a gas outlet 16b of the mechanical booster pump 16, respectively.

[0091] As shown in FIG. 5, a spray nozzle 54 is provided in the gas pipe 14 near the gas inlet 16a of the mechanical booster pump 16, which sprays and introduces ordinary tap water into the mechanical booster pump 16 as cleaning water.

[0092] On the other hand, as shown in Figure 5, the mechanical booster pump 16 has two cocoon-shaped rotors 16d and a drive gear (timing gear) (not shown) mounted in a casing 16c so that they can rotate integrally with a pivot 16e. The drive gears rotate synchronously in opposite directions. When the pivot 16e and the cocoon-shaped rotor 16d rotate together with the drive gear, the two cocoon-shaped rotors 16d also rotate synchronously in opposite directions. The used gas G1 that has entered through the gas inlet 16a is trapped in the space between the casing 16c and the two cocoon-shaped rotors 16d, and is then discharged to the gas outlet 16b by the rotation of the cocoon-shaped rotors 16d and sent to the gas inlet 15a of the vacuum pump 15 through the gas piping 14. Here, the cocoon-shaped rotors 16d rotate while maintaining a small gap (0.1 to 0.3 mm) without contacting each other or the casing 16c, and transport the used gas G1. As a result, similar to the vacuum pump 15, the gas remaining inside the mechanical booster pump 16 solidifies as a film or powder and becomes deposits (mainly SiO2: silica), and these deposits adhere to the inside of the dry pump in a short period of time, causing operational malfunctions.

[0093] Therefore, in this embodiment, if the vacuum pump 15 and the mechanical booster pump 16 are stopped and then clogged with internal deposits when an attempt is made to restart them, causing the rotors 21a to 21f and the cocoon-shaped rotor 16d to become locked, a cleaning liquid is passed through the mechanical booster pump 16 and then introduced into the vacuum pump 15, and the deposits inside the mechanical booster pump 16 and the vacuum pump 15 are washed and removed with the cleaning liquid, and then the deposits are discharged to the outside of the mechanical booster pump 16 and the vacuum pump 15.

[0094] The supply of cleaning liquid to the mechanical booster pump 16 is achieved by connecting the water supply pipe 41A shown in Fig. 4 to the spray nozzle 54 shown in Fig. 5. A flow meter 55A and an on-off valve 57A controlled by the control unit 32 are provided midway along the water supply pipe 41A. The flow meter 55A measures the flow rate of the cleaning liquid supplied to the mechanical booster pump 16 through the water supply pipe 41A, and the on-off valve 57A turns the supply of cleaning liquid to the mechanical booster pump 16 on and off.

[0095] The spray nozzle 54 is provided in the gas pipe 14 corresponding to the gas inlet 16a of the mechanical booster pump 16. The position at which the spray nozzle 54 is provided in the gas pipe 14 is determined in consideration of the inner diameter D of the gas inlet 16a so that when the cleaning liquid is sprayed in a mist toward the inside of the mechanical booster pump 16, the mist of cleaning liquid spreads in a cone shape and the spray range W within the mechanical booster pump 16 is as wide as possible, as shown in Fig. 5 .

[0096] 4, the cleaning unit 31 includes a three-way valve 35, a cleaning liquid storage tank 36, a vacuum container 38, a vacuum pump 39, and a control unit 32. The control unit 32 here is equipped with a microcomputer that has installed therein a program capable of controlling the cleaning unit 31, the flow meter 55, etc. in accordance with predetermined procedures.

[0097] The three-way valve 35 has three ports: a first port 35a, a second port 35b, and a third port 35c. One end of a drain pipe 42A is connected to the first port 35a, and one end of a drain pipe 42B is connected to the third port 35c. The second port 35b is open and always closed.

[0098] The other end of the drain pipe 42 is connected to the cleaning liquid storage tank 36 via the vacuum container 38, an adjustable on-off valve 49, and a vacuum pump 39. When the second port 35b of the three-way valve 35 is closed and the first port 35a and the third port 35c are opened, the drain pipe 42B draws the cleaning liquid introduced into the vacuum pump 15 out of the vacuum pump 15 through the drain pipe 42A, the drain pipe 42B, the vacuum container 38, and the vacuum pump 39, and the drawn cleaning liquid can be returned into the cleaning liquid storage tank 36.

[0099] In this embodiment, the inert gas introduction unit 50 used in the first embodiment is used to send the inert gas in the inert gas supply tank 51 into the oil box 27 and the oil box 28 during cleaning, making the pressure in the oil box 27 and the oil box 28 more positive than the pressure in the gas flow path, and preventing the cleaning liquid from penetrating into the oil box 27 and the oil box 28. Although not shown in the figure, this is applied in the same way as in the first embodiment.

[0100] Next, in the configuration of this embodiment, an example of a procedure for performing a cleaning process to restart the mechanical booster pump 16 and the vacuum pump 15 when the mechanical booster pump 16 and the vacuum pump 15 are locked and stopped due to deposits in the mechanical booster pump 16 or deposits in the vacuum pump 15 will be described in the order of steps (1) to (11).

[0101] (1) First, the portable cart 45 carrying the cleaning unit 31, the inert gas introduction unit 50, etc. is transported near the vacuum pump 15 and the mechanical booster pump 16 that need to be cleaned.

[0102] (2) Next, the gas exhaust pipe 18 is removed from the gas exhaust port 15b of the vacuum pump 15, and instead the drainage pipe 42A of the cleaning unit 31 is connected to the gas exhaust port 15b. In this state, the first port 35a, the second port 35b, and the third port 35c of the three-way valve 35 are all closed, and the operation of the cleaning unit 31 is also stopped. Then, the water supply pipe 41A is connected to the spray nozzle 54 provided corresponding to the gas inlet 16a of the mechanical booster pump 16.

[0103] (3) Next, the inert gas supply pipe 52 is connected to the inert gas inlet 30 on the oil box 27 side of the vacuum pump 15 and the inert gas inlet 30 on the oil box 28 side. In this state, the on / off adjustment valve 53 of the inert gas introduction unit 50 is closed. This completes preparations for cleaning the vacuum pump 15 using the cleaning unit 31 and the inert gas introduction unit 50. Next, the cleaning operation of the vacuum pump 15 begins.

[0104] (4) In the cleaning operation of the vacuum pump 15, processing is performed in a predetermined procedure under the control of the control unit 32. First, the on-off adjustment valve 53 of the inert gas introduction unit 50 is opened, and inert gas is introduced from the inert gas supply tank 51 through the inert gas supply piping 52 into the oil box 27 and the oil box 28. Then, the introduction of the inert gas makes the pressure inside the oil box 27 and the oil box 28 more positive than the pressure inside the gas flow path. Thereafter, the on-off valve 57 is opened under the control of the control unit 32B, and cleaning water is supplied to the spray nozzle 54 from the water supply piping 41A.

[0105] (5) When cleaning water is supplied from the water supply pipe 41A to the spray nozzle 54, the cleaning liquid is sprayed from the spray nozzle 54, and this atomized cleaning liquid is sprayed through the gas inlet 16a onto the two cocoon-shaped rotors 16d of the mechanical booster pump 16. Then, the inside of the mechanical booster pump 16, including the cocoon-shaped rotors 16d, is cleaned with this sprayed cleaning liquid.

[0106] (6) After cleaning the inside of the mechanical booster pump 16, the cleaning liquid is discharged from the gas outlet 16b of the mechanical booster pump 16 into the gas pipe 14. The cleaning liquid discharged into the gas pipe 14 is introduced into the vacuum pump 15 from the gas inlet 15a, and the inside of the vacuum pump 15 is cleaned. The amount of cleaning liquid supplied into the vacuum pump 15 through the mechanical booster pump 16 is, for example, about 5 liters, and this amount is measured by the flow meter 55A. When the amount reaches a predetermined amount, the control unit 32 controls the on-off valve 57A to stop the supply of new cleaning liquid to the spray nozzle 54.

[0107] (7) Furthermore, as the cleaning liquid discharged from the mechanical booster pump 16 is introduced into the vacuum pump 15, the control unit 32 operates the vacuum pump 39. When the vacuum pump 39 operates, the cleaning liquid that had been introduced into each gas flow path is discharged together with the deposits through the drain pipe 42A, the first port 35a, the third port 35c, the drain pipe 42B, and the vacuum pump 39 into the cleaning liquid storage tank 36. Once the cleaning liquid has been discharged from each gas flow path in the mechanical booster pump 16 and the vacuum pump 15 in this manner, the on-off adjustment valve 53 of the inert gas introduction unit 50 is closed while continuing to operate the vacuum pump 39, the inert gas that had been introduced into the oil box 27 and the oil box 28 is stopped, and the pressure inside the oil box 27 and the oil box 28 is returned to approximately the same as the pressure inside the gas flow path.

[0108] (8) Next, the operator manually attempts to rotate the pivot 16e of the mechanical booster pump 16 integrally with the cocoon-shaped rotor 16d, and also attempts to rotate the rotary shafts 22a and 22b of the vacuum pump 15 integrally with the rotors 21a to 21f. Here, while the operator is manually rotating the mechanical booster pump 16 and the vacuum pump 15, the control unit 32 opens the on-off valve 57A, and continuously introduces a total of 50 liters of cleaning liquid from the spray nozzle 54 at a flow rate of, for example, about 7 lpm through the mechanical booster pump 16 into the vacuum pump 15. The introduced cleaning liquid is continuously discharged from the gas outlet 15b of the vacuum pump 15 into the cleaning liquid storage tank 36. This manual rotation work softens and dissolves the deposits accumulated inside the mechanical booster pump 16 and the vacuum pump 15 by immersing them in the cleaning liquid, and the pivot 16e can easily rotate integrally with the cocoon-shaped rotor 16d, and the rotating shafts 22a and 22b can also easily rotate integrally with the rotors 21a to 21f. This manual rotation removes deposits that have adhered to the inner surface of the mechanical booster pump 16, the surface of the cocoon-shaped rotor 16d, etc., and the inner surface of the pump casing 20, the surfaces of the rotors 21a to 21f, etc. Once the deposits adhering to the mechanical booster pump 16 and the pump casing 20 have been removed, the pivot 16e of the mechanical booster pump 16 can be manually rotated integrally with the cocoon-shaped rotor 16d, and the rotating shafts 22a and 22b of the vacuum pump 15 can be manually rotated integrally with the rotors 21a to 21f. If it is confirmed that the torque generated by this manual rotation is equal to or less than a predetermined value, the process proceeds to the next step (9). On the other hand, if the torque is equal to or greater than the predetermined value, the process returns to step (4) and repeats the same processes of steps (4) to (8).

[0109] Once it is confirmed that the manual torque (9) and (8) is below a predetermined value, the drying process begins. During the drying process, the vacuum pump 39 is left in an idle state for a while. During this idle operation, outside air is drawn in through the gas inlet 16a of the mechanical booster pump 16. The outside air drawn into the mechanical booster pump 16 passes through the gas flow paths of the mechanical booster pump 16 and the vacuum pump 15, then is discharged through the gas outlet 15b of the vacuum pump 15, and then flows through the drain pipe 42A, the first port 35a, the third port 35c, the drain pipe 42B, and the vacuum pump 39. This air flow dries the gas flow path. The drying operation takes approximately two hours. During the drying operation, the control unit 32 controls the inert gas introduction unit 50 to flow into the oil boxes 27 and 28, thereby drying the interiors of the oil boxes 27 and 28.

[0110] (10) After the cleaning and drying operations of the mechanical booster pump 16 and the vacuum pump 15 are completed, the control unit 32 closes the on-off adjustment valve 53 of the inert gas introduction unit 50 to stop the introduction of the inert gas into the oil box 27 and the oil box 28. After the introduction of the inert gas is stopped, the inert gas supply pipe 52 is removed from the vacuum pump 15.

[0111] (11) Next, the water supply pipe 41A is removed from the spray nozzle 54 of the mechanical booster pump 16, and the drain pipe 42A is removed from the gas outlet 15b of the vacuum pump 15. Then, by connecting the gas exhaust pipe 18 to the gas outlet 15b of the vacuum pump 15 that has been cleaned, the exhaust gas treatment device can be restored to a state similar to that shown in FIG.

[0112] Therefore, according to the vacuum pumping system of this embodiment, the water supply pipe 41A connected to the spray nozzle 54 of the mechanical booster pump 16 is connected to a faucet of a public water supply, and public water is run through the gas passage and used as a cleaning liquid, which simplifies cleaning and also reduces costs. Also, both the mechanical booster pump 16 and the vacuum pump 15 can be cleaned simultaneously.

[0113] <Third Example> FIG. 6 shows a third embodiment of the vacuum pumping system, and is a configuration diagram showing the overall schematic configuration of the system in the third embodiment together with a vacuum pump 15 and the like. The third embodiment shown in FIG. 6 is a modified version of part of the configuration of the first embodiment shown in FIG. 3 and part of the configuration of the second embodiment shown in FIG. 4. Therefore, the same components as those in FIGS. 3 and 4 are given the same reference numerals, and redundant explanations will be omitted, and the following description will mainly focus on the differences from the embodiment shown in FIGS. 3 and 4. In the following description, members that are given the same reference numerals as those in FIGS. 1 to 5 correspond to the members shown in FIGS. 1 to 5.

[0114] The third embodiment shown in Fig. 6 differs from the first embodiment shown in Fig. 3 in that in the first embodiment, the cleaning liquid stored in the cleaning liquid storage tank 36 or the cleaning liquid stored in the water tank 33 is flowed into the vacuum pump 15 from the gas outlet 15b side of the vacuum pump 15 to clean only the vacuum pump 15, whereas in the third embodiment, the cleaning liquid stored in the cleaning liquid storage tank 36 can be used to simultaneously clean both the mechanical booster pump 16 and the vacuum pump 15. On the other hand, the third embodiment shown in Fig. 6 differs from the second embodiment shown in Fig. 4 in that in the second embodiment, the water supply pipe 41A is connected to a faucet of an ordinary water supply, and ordinary tap water is used as the cleaning liquid to simultaneously clean both the mechanical booster pump 16 and the vacuum pump 15, whereas in the third embodiment shown in Fig. 6, the cleaning liquid stored in the cleaning liquid storage tank 36 can be used to simultaneously clean both the mechanical booster pump 16 and the vacuum pump 15.

[0115] 5 is connected to one end of a water supply pipe 41, the other end of which is connected to the cleaning liquid storage tank 36 via the cleaning liquid introduction pump 37. When the on-off valve 34 is opened and the cleaning liquid introduction pump 37 is driven, the cleaning liquid in the cleaning liquid storage tank 36 is sent to the spray nozzle 54, and the cleaning liquid is sprayed from the spray nozzle 54 into the mechanical booster pump 16.

[0116] In FIG. 6 showing this embodiment, the inert gas introduction unit 50 used in the first embodiment is used to send the inert gas in the inert gas supply tank 51 into the oil box 27 and the oil box 28 during cleaning, making the pressure in the oil box 27 and the oil box 28 more positive than the pressure in the gas flow path, respectively, and measures to prevent the cleaning liquid from penetrating into the oil box 27 and the oil box 28 are omitted, but are applied in the same way as in the first embodiment.

[0117] Next, in the configuration of this embodiment, when the mechanical booster pump 16 and the vacuum pump 15 are locked and stopped due to deposits in the mechanical booster pump 16 or the vacuum pump 15, an example of a cleaning procedure for restarting the mechanical booster pump 16 and the vacuum pump 15 will be described in the order of steps (1) to (12).

[0118] (1) First, the portable cart 45 carrying the cleaning unit 31, the inert gas introduction unit 50, etc. is transported near the vacuum pump 15 and the mechanical booster pump 16 that need to be cleaned.

[0119] (2) Next, the gas exhaust pipe 18 is removed from the gas exhaust port 15b of the vacuum pump 15, and instead the drainage pipe 42A of the cleaning unit 31 is connected to the gas exhaust port 15b. In this state, the first port 35a, the second port 35b, and the third port 35c of the three-way valve 35 are all closed, and the operation of the cleaning unit 31 is also stopped. Next, the water supply pipe 41 is connected to the spray nozzle 54 provided corresponding to the gas inlet 16a of the mechanical booster pump 16.

[0120] (3) Next, the inert gas supply pipe 52 is connected to the inert gas inlet 30 on the oil box 27 side of the vacuum pump 15 and the inert gas inlet 30 on the oil box 28 side. In this state, the on / off adjustment valve 53 of the inert gas introduction unit 50 is closed. This completes preparations for cleaning the vacuum pump 15 using the cleaning unit 31 and the inert gas introduction unit 50. Next, the cleaning operation of the vacuum pump 15 begins.

[0121] (4) In the cleaning operation of the vacuum pump 15, processing is performed in a predetermined procedure under the control of the control unit 32. First, the on-off adjustment valve 53 of the inert gas introduction unit 50 is opened, and inert gas is introduced from the inert gas supply tank 51 through the inert gas supply piping 52 into the oil box 27 and the oil box 28. Then, by introducing the inert gas, the pressure inside the oil box 27 and the pressure inside the oil box 28 become more positive than the pressure inside the gas flow path. After this state is achieved, the on-off valve 34 is opened under the control of the control unit 32, and the cleaning liquid introduction pump 37 is driven, and the cleaning liquid in the cleaning liquid storage tank 36 is supplied to the spray nozzle 54 through the water supply piping 41.

[0122] (5) When cleaning water is supplied from the water supply pipe 41 to the spray nozzle 54, the cleaning liquid is sprayed from the spray nozzle 54, and this atomized cleaning liquid is sprayed through the gas inlet 16a onto the two cocoon-shaped rotors 16d of the mechanical booster pump 16. Then, the cocoon-shaped rotors 16d are cleaned with this sprayed cleaning liquid.

[0123] (6) After cleaning the inside of the mechanical booster pump 16, the cleaning liquid is discharged from the gas outlet 16b of the mechanical booster pump 16 into the gas pipe 14. The cleaning liquid discharged into the gas pipe 14 is introduced into the vacuum pump 15 from the gas inlet 15a, and the inside of the vacuum pump 15 is cleaned. The amount of cleaning liquid supplied to the vacuum pump 15 through the mechanical booster pump 16 is, for example, about 5 liters. The amount of supply is measured by the flow meter 55B, and when the amount of supply reaches a predetermined amount, the control unit 32 controls to close the on-off valve 34 and stop the operation of the cleaning liquid introduction pump 37. This stops the supply of new cleaning liquid to the spray nozzle 54.

[0124] (7) Furthermore, as the cleaning liquid discharged from the mechanical booster pump 16 is introduced into the vacuum pump 15, the control unit 32 operates the vacuum pump 39. When the vacuum pump 39 operates, the cleaning liquid introduced into each gas flow path is discharged together with the deposits through the drain pipe 42A, the first port 35a, the third port 35c, the drain pipe 42B, and the vacuum pump 39 into the cleaning liquid storage tank 36. Once the cleaning liquid has been discharged from each gas flow path in the mechanical booster pump 16 and the vacuum pump 15 in this manner, the on-off adjustment valve 53 of the inert gas introduction unit 50 is closed while continuing to operate the vacuum pump 39, the inert gas being introduced into the oil box 27 and the oil box 28 is stopped, and the pressure inside the oil box 27 and the oil box 28 is returned to approximately the same as the pressure inside the gas flow path.

[0125] (8) Next, the operator manually attempts to rotate the pivot 16e of the mechanical booster pump 16 integrally with the cocoon-shaped rotor 16d, and also attempts to rotate the rotary shafts 22a and 22b of the vacuum pump 15 together with the rotors 21a to 21f. Here, while the mechanical booster pump 16 and the vacuum pump 15 are being manually rotated, the control unit 32 controls the opening of the on-off valve 34 and the driving of the cleaning liquid introduction pump 37, and continuously introduces a total of 50 liters of cleaning liquid from the spray nozzle 54 through the mechanical booster pump 16 into the vacuum pump 15 at a flow rate of, for example, about 7 lpm. The introduced cleaning liquid is continuously discharged from the gas outlet 15b of the vacuum pump 15 into the cleaning liquid storage tank 36. This manual rotation work softens and dissolves the deposits accumulated inside the mechanical booster pump 16 and the vacuum pump 15 by immersing them in the cleaning liquid, allowing the pivot 16e to easily rotate integrally with the cocoon-shaped rotor 16d, and the rotating shafts 22a and 22b to easily rotate integrally with the rotors 21a to 21f. This manual rotation removes deposits that have adhered to the inner surface of the mechanical booster pump 16, the surface of the cocoon-shaped rotor 16d, etc., and the inner surface of the pump casing 20, the surfaces of the rotors 21a to 21f, etc. Here, once the deposits adhering to the mechanical booster pump 16 and the pump casing 20 have been removed, the pivot 16e of the mechanical booster pump 16 can be manually rotated integrally with the cocoon-shaped rotor 16d, and the rotating shafts 22a and 22b of the vacuum pump 15 can be manually rotated integrally with the rotors 21a to 21f. If it is confirmed that the torque generated by this manual rotation is equal to or less than a predetermined value, the process proceeds to the next step (9). On the other hand, if the torque is equal to or greater than the predetermined value, the process returns to step (4) and repeats the same steps (4) to (8).

[0126] Once it is confirmed that the manual torque (9) and (8) is below a predetermined value, the drying process begins. During this process, the vacuum pump 39 is left in an idle state for a while. During this idle operation, outside air is drawn in through the gas inlet 16a of the mechanical booster pump 16, passes through the gas flow paths of the mechanical booster pump 16 and the vacuum pump 15, and is then discharged through the gas outlet 15b of the vacuum pump 15. The air then flows through the drain pipe 42A, the first port 35a, the third port 35c, the drain pipe 42B, and the vacuum pump 39. This air flow dries the gas flow paths. The drying operation takes approximately two hours. During the drying operation, inert gas is flowed from the inert gas introduction unit 50 into the oil boxes 27 and 28 to dry the interiors of the oil boxes 27 and 28.

[0127] (10) After the cleaning and drying operations of the mechanical booster pump 16 and the vacuum pump 15 are completed, the control unit 32 closes the on-off adjustment valve 53 of the inert gas introduction unit 50, stops the introduction of inert gas into the oil box 27 and the oil box 28, and removes the inert gas supply pipe 52 from the vacuum pump 15.

[0128] (11) Next, the water supply pipe 41 is removed from the spray nozzle 54 of the mechanical booster pump 16, and the drain pipe 42A is removed from the gas outlet 15b of the vacuum pump 15. Then, by connecting the gas exhaust pipe 18 to the gas outlet 15b of the vacuum pump 15 that has been cleaned, the exhaust gas treatment device can be restored to a state similar to that shown in FIG.

[0129] Therefore, according to the vacuum pumping system of this embodiment, by connecting the water supply pipe 41 to the spray nozzle 54 of the mechanical booster pump 16, the cleaning liquid in the cleaning liquid storage tank 36 can be used to simultaneously clean the mechanical booster pump 16 and the vacuum pump 15.

[0130] <Fourth Example> FIG. 7 shows a fourth embodiment of the vacuum pumping system, and is a configuration diagram showing the schematic overall configuration of the system in the fourth embodiment together with a vacuum pump 15 and the like. The fourth embodiment shown in FIG. 7 is a modification of part of the configuration of the first embodiment shown in FIG. 3 and part of the configuration of the second embodiment shown in FIG. 4. Therefore, the same components as those in FIGS. 3 and 4 are given the same reference numerals, and redundant explanations will be omitted, and the following description will mainly focus on differences from the embodiments shown in FIGS. 3 and 4. In the following description, members that are given the same reference numerals as those in FIGS. 1 to 6 correspond to the members shown in FIGS. 1 to 6.

[0131] The fourth embodiment shown in FIG. 7 differs from the first embodiment shown in FIG. 3 in that, in the first embodiment, cleaning liquid stored in cleaning liquid storage tank 36 or cleaning liquid stored in water tank 33 is flowed into vacuum pump 15 from gas outlet 15b of vacuum pump 15 to clean vacuum pump 15. In contrast, in the fourth embodiment, a polyethylene tank 56 or the like containing approximately 10 liters of cleaning liquid is prepared, and the cleaning liquid stored in polyethylene tank 56 is flowed into vacuum pump 15 from gas inlet 15a to clean vacuum pump 15. A water supply pipe 41B connectable to gas inlet 15a of vacuum pump 15 extends from polyethylene tank 56, and an on-off valve 57 controlled by control unit 32 is provided midway along water supply pipe 41B. The polyethylene tank 56 is incorporated into cleaning unit 31 shown in FIG. 1 and can be transported together with cleaning unit 31 on dolly 45 to the location where cleaning is required.

[0132] On the other hand, the difference between the fourth embodiment shown in FIG. 7 and the second embodiment shown in FIG. 4 is that in the second embodiment, the water supply pipe 41A is connected to a faucet of a regular water supply, and regular tap water is used as a cleaning liquid to simultaneously clean both the mechanical booster pump 16 and the vacuum pump 15, whereas in the fourth embodiment shown in FIG. 7, a spray nozzle 54 is provided in the gas pipe 14 between the mechanical booster pump 16 and the vacuum pump 15, and the water supply pipe 41B extending from a plastic tank 56 is connected to the spray nozzle 54, and the cleaning liquid stored in the plastic tank 56 is passed through the spray nozzle 54 and flows into the vacuum pump 15 from the gas inlet 15a side, thereby cleaning the vacuum pump 15.

[0133] 7, a spray nozzle 54 identical to the spray nozzle 54 shown in Fig. 5 is provided in the gas pipe 14 connecting the mechanical booster pump 16 and the vacuum pump 15. The spray nozzle 54 here is provided at a position where it can spray and introduce cleaning water into the gas inlet 15a of the vacuum pump 15.

[0134] In FIG. 7 showing this embodiment, the inert gas introduction unit 50 used in the first embodiment is used to send the inert gas in the inert gas supply tank 51 into the oil box 27 and the oil box 28 during cleaning, making the pressure in the oil box 27 and the oil box 28 more positive than the pressure in the gas flow path, respectively, and measures to prevent the cleaning liquid from entering the oil box 27 and the oil box 28 are omitted, but are applied in the same way as in the first embodiment.

[0135] Next, in the configuration of this embodiment, an example of a cleaning procedure for restarting the vacuum pump 15 when the vacuum pump 15 is locked and stopped due to deposits inside the vacuum pump 15 will be described in the order of steps (1) to (9).

[0136] (1) First, the portable cart 45 carrying the cleaning unit 31 with the polyethylene tank 56, the inert gas introduction unit 50, etc. is transported near the vacuum pump 15 that needs to be cleaned.

[0137] (2) Next, the water supply pipe 41B extending from the polyethylene tank 56 is connected to the spray nozzle 54 provided on the gas pipe between the vacuum pump 15 and the mechanical booster pump 16, and the gas exhaust pipe 18 is removed from the gas exhaust port 15b of the vacuum pump 15, and instead the drain pipe 42A of the cleaning unit 31 is connected to the gas exhaust port 15b. In this state, the first port 35a, the second port 35b, and the third port 35c of the three-way valve 35 are all closed, and the operation of the cleaning unit 31 is also stopped.

[0138] (3) Next, the inert gas supply pipe 52 is connected to the inert gas inlet 30 on the oil box 27 side of the vacuum pump 15 and the inert gas inlet 30 on the oil box 28 side. In this state, the on / off adjustment valve 53 of the inert gas introduction unit 50 is closed. This completes preparations for cleaning the vacuum pump 15 using the cleaning unit 31 and the inert gas introduction unit 50. Next, the cleaning operation of the vacuum pump 15 begins.

[0139] (4) In the cleaning operation of the vacuum pump 15, processing is performed in a predetermined procedure under the control of the control unit 32. First, the on-off adjustment valve 53 of the inert gas introduction unit 50 is opened, and inert gas is introduced from the inert gas supply tank 51 through the inert gas supply pipe 52 into the oil box 27 and the oil box 28. Then, by introducing the inert gas, the pressure inside the oil box 27 and the pressure inside the oil box 28 become more positive than the pressure inside the gas flow path. After this state is achieved, the on-off valve 57 is opened under the control of the control unit 32, and cleaning water from the plastic tank 56 is supplied to the spray nozzle 54.

[0140] (5) When cleaning water is supplied from the polyethylene tank 56 to the spray nozzle 54, the cleaning liquid is sprayed from the spray nozzle 54. The atomized cleaning liquid is then introduced into the vacuum pump 15 through the gas inlet 15a, and the inside of the vacuum pump 15 is cleaned. The amount of cleaning liquid supplied to the vacuum pump 15 here is, for example, about 5 liters, and is measured by the flow meter 55B. When the amount reaches a predetermined amount, the control unit 32 closes the on-off valve 57 and stops the supply of new cleaning liquid to the spray nozzle 54.

[0141] (6) Furthermore, as the cleaning liquid sprayed from the spray nozzle 54 is introduced into the vacuum pump 15, the control unit 32 operates the vacuum pump 39. When the vacuum pump 39 operates, the cleaning liquid introduced into the gas flow path dissolves and cleans the deposits, and the cleaning liquid is discharged together with the deposits through the drain pipe 42A, the first port 35a, the third port 35c, the drain pipe 42B, and the vacuum pump 39 into the cleaning liquid storage tank 36. After the cleaning liquid has been discharged from the vacuum pump 15 in this manner, the on-off adjustment valve 53 of the inert gas introduction unit 50 is closed while the vacuum pump 39 continues to operate, the inert gas being introduced into the oil box 27 and the oil box 28 is stopped, and the pressure inside the oil box 27 and the oil box 28 is returned to approximately the same as the pressure inside the gas flow path.

[0142] (7) Next, the operator manually attempts to rotate the rotating shafts 22a and 22b of the vacuum pump 15 integrally with the rotors 21a to 21f. While the vacuum pump 15 is being rotated manually, the control unit 32 opens the on-off valve 57, and a predetermined amount of cleaning liquid is continuously introduced into the vacuum pump 15 from the spray nozzle 54. The introduced cleaning liquid is continuously discharged into the cleaning liquid storage tank 36 from the gas outlet 15b of the vacuum pump 15. This manual rotation softens and dissolves the deposits accumulated inside the vacuum pump 15, allowing the rotating shafts 22a and 22b to easily rotate integrally with the rotors 21a to 21f. This manual rotation removes deposits adhering to the inner surface of the pump casing 20 of the vacuum pump 15 and the surfaces of the rotors 21a to 21f. Once the deposits inside the vacuum pump 15 have been removed, the rotating shafts 22a and 22b can be easily rotated manually together with the rotors 21a to 21f. If it is confirmed that the torque generated by this manual rotation is equal to or less than a predetermined value, the process proceeds to the next step (8). However, if the torque is equal to or greater than the predetermined value, the process returns to step (3) and repeats the same steps (3) to (7).

[0143] Once it is confirmed that the manual torque (8) and (7) is below the preset value, the drying process begins. During the drying process, the vacuum pump 39 is left in an idle state for a while. During this idle operation, outside air is drawn in through the gas inlet 15a of the vacuum pump 15, passes through the gas flow path of the vacuum pump 15, and is then discharged through the gas outlet 15b of the vacuum pump 15. The air then flows through the drain pipe 42A, the first port 35a, the third port 35c, the drain pipe 42B, and the vacuum pump 39. This air flow dries the gas flow path. The drying operation takes approximately two hours. During the drying operation, inert gas is flowed from the inert gas introduction unit 50 into the oil boxes 27 and 28 to dry the interiors of the oil boxes 27 and 28.

[0144] (9) Furthermore, when the cleaning and drying operations of the vacuum pump 15 are completed, the control unit 32 closes the on / off adjustment valve 53 of the inert gas introduction unit 50 to stop the introduction of the inert gas into the oil box 27 and the oil box 28. Then, the inert gas supply piping 52 is removed from the vacuum pump 15. Next, the water supply piping 41B is removed from the spray nozzle 54, and the drain piping 42A is removed from the gas outlet 15b of the vacuum pump 15. Furthermore, by connecting the gas exhaust piping 18 to the gas outlet 15b of the vacuum pump 15 that has been cleaned, the exhaust gas treatment device can be restored to a state similar to that shown in FIG.

[0145] Therefore, according to the vacuum exhaust system of this embodiment, by connecting the water supply pipe 41B extending from the plastic tank 56 to the spray nozzle 54, the vacuum pump 15 can be cleaned using the cleaning liquid prepared in the plastic tank 56.

[0146] <Fifth Example> FIG. 8 shows a fifth embodiment of the vacuum pumping system, and is a configuration diagram showing the overall configuration of the system in the fifth embodiment together with the vacuum pump 15 and other components. The fifth embodiment shown in FIG. 8 is a modified version of part of the configuration of the first embodiment shown in FIG. 3 and part of the configuration of the fourth embodiment shown in FIG. 6. Therefore, the same components as those in FIGS. 3 and 6 are given the same reference numerals, and redundant explanations will be omitted. The following description will mainly focus on differences from the embodiments shown in FIGS. 3 and 4. In the following description, members that are given the same reference numerals as those in FIGS. 1 to 7 correspond to the members shown in FIGS. 1 to 7.

[0147] The difference between the fifth embodiment shown in FIG. 8 and the first embodiment shown in FIG. 3 is that in the first embodiment, the cleaning liquid stored in the cleaning liquid storage tank 36 or the cleaning liquid stored in the water tank 33 is made to flow into the vacuum pump 15 from the gas outlet 15b side of the vacuum pump 15 to clean the vacuum pump 15, whereas in the fifth embodiment, the cleaning liquid stored in the cleaning liquid storage tank 36 is made to flow into the vacuum pump 15 from the gas inlet 15a side to clean the vacuum pump 15.

[0148] On the other hand, the difference between the fifth embodiment shown in FIG. 8 and the fourth embodiment shown in FIG. 6 is that in the fourth embodiment, a spray nozzle 54 is provided in the gas pipe 14 between the mechanical booster pump 16 and the vacuum pump 15, and a water supply pipe 41B extending from a polyethylene tank 56 is connected to the spray nozzle 54, so that the cleaning liquid stored in the polyethylene tank 56 is passed through the spray nozzle 54 and flows into the vacuum pump 15 from the gas inlet 15a side, thereby cleaning the vacuum pump 15.

[0149] 8, a spray nozzle 54 identical to the spray nozzle 54 shown in Fig. 5 is provided in the middle of the gas pipe 14 connecting the mechanical booster pump 16 and the vacuum pump 15. The spray nozzle 54 here is provided at a position where it can spray and introduce cleaning water into the gas inlet 15a of the vacuum pump 15.

[0150] In FIG. 8 showing this embodiment, the inert gas introduction unit 50 used in the first embodiment is used to send the inert gas in the inert gas supply tank 51 into the oil box 27 and the oil box 28 during cleaning, making the pressure in the oil box 27 and the oil box 28 more positive than the pressure in the gas flow path, respectively, and measures to prevent the cleaning liquid from entering the oil box 27 and the oil box 28 are omitted, but are applied in the same way as in the first embodiment.

[0151] Next, in the configuration of this embodiment, an example of a cleaning procedure for restarting the vacuum pump 15 when the vacuum pump 15 is locked and stopped due to deposits inside the vacuum pump 15 will be described in the order of steps (1) to (9).

[0152] (1) First, the portable cart 45 carrying the cleaning unit 31, the inert gas introduction unit 50, etc. is transported near the vacuum pump 15 that needs to be cleaned.

[0153] (2) Next, the water supply pipe 41 leading to the cleaning liquid storage tank 36 is connected to the spray nozzle 54 provided in the gas pipe between the vacuum pump 15 and the mechanical booster pump 16, and the gas exhaust pipe 18 is removed from the gas exhaust port 15b of the vacuum pump 15. Instead, the drain pipe 42A of the cleaning unit 31 is connected to the gas exhaust port 15b. In this state, the first port 35a, the second port 35b, and the third port 35c of the three-way valve 35 are all closed, and the operation of the cleaning unit 31 is also stopped.

[0154] (3) Next, the inert gas supply pipe 52 is connected to the inert gas inlet 30 on the oil box 27 side of the vacuum pump 15 and the inert gas inlet 30 on the oil box 28 side. In this state, the on / off adjustment valve 53 of the inert gas introduction unit 50 is closed. This completes preparations for cleaning the vacuum pump 15 using the cleaning unit 31 and the inert gas introduction unit 50. Next, the cleaning operation of the vacuum pump 15 begins.

[0155] (4) In the cleaning operation of the vacuum pump 15, processing is performed in a predetermined procedure under the control of the control unit 32. First, the on-off adjustment valve 53 of the inert gas introduction unit 50 is opened, and inert gas is introduced from the inert gas supply tank 51 through the inert gas supply pipe 52 into the oil box 27 and the oil box 28. Then, by introducing the inert gas, the pressure inside the oil box 27 and the pressure inside the oil box 28 become more positive than the pressure inside the gas flow path. After this state is achieved, the on-off valve 34 is opened under the control of the control unit 32, and the cleaning liquid introduction pump 37 of the cleaning unit 31 is operated, and cleaning water from the cleaning liquid introduction pump 37 is supplied to the spray nozzle 54.

[0156] (5) When cleaning water is supplied from the cleaning liquid introduction pump 37 to the spray nozzle 54, the cleaning liquid is sprayed from the spray nozzle 54. The atomized cleaning liquid is then introduced into the vacuum pump 15 through the gas inlet 15a, and the inside of the vacuum pump 15 is cleaned. The amount of cleaning liquid supplied to the vacuum pump 15 here is, for example, about 5 liters, and is measured by a flow meter (not shown). When the amount reaches a predetermined amount, the control unit 32 closes the on-off valve 34 and stops the operation of the cleaning liquid introduction pump 37, thereby stopping the supply of new cleaning liquid to the spray nozzle 54.

[0157] (6) Furthermore, when the cleaning liquid is introduced into the vacuum pump 15, the control unit 32 operates the vacuum pump 39. When the vacuum pump 39 operates, the cleaning liquid introduced into the gas flow path cleans the deposits, and the cleaning liquid is discharged together with the deposits through the drain pipe 42A, the first port 35a, the third port 35c, the drain pipe 42B, and the vacuum pump 39 into the cleaning liquid storage tank 36. Once the cleaning liquid has been discharged from the vacuum pump 15 in this manner, the on-off adjustment valve 53 of the inert gas introduction unit 50 is closed while continuing to operate the vacuum pump 39, the inert gas being introduced into the oil box 27 and the oil box 28 is stopped, and the pressure inside the oil box 27 and the oil box 28 is returned to approximately the same as the pressure in the gas flow path.

[0158] (7) Next, the operator manually attempts to rotate the rotating shafts 22a and 22b of the vacuum pump 15 together with the rotors 21a to 21f. While the vacuum pump 15 is being rotated by hand, the control unit 32 opens the on-off valve 34 and operates the cleaning liquid introduction pump 37, continuously introducing a predetermined amount of cleaning liquid into the vacuum pump 15 through the spray nozzle 54. The introduced cleaning liquid is continuously discharged into the cleaning liquid storage tank 36 through the gas outlet 15b of the vacuum pump 15. This manual rotation softens and dissolves the deposits accumulated inside the vacuum pump 15 by immersion in the cleaning liquid, allowing the rotating shafts 22a and 22b to rotate together with the rotors 21a to 21f. This manual rotation removes deposits adhering to the inner surface of the pump casing 20 of the vacuum pump 15 and the surfaces of the rotors 21a to 21f. Once the deposits inside the vacuum pump 15 have been removed, the rotating shafts 22a and 22b can be easily rotated together with the rotors 21a to 21f. If it is confirmed that the torque generated by this manual rotation is equal to or less than a predetermined value, the process proceeds to the next step (8). However, if the torque is equal to or greater than the predetermined value, the process returns to step (3) and repeats the same steps (3) to (6).

[0159] Once it is confirmed that the manual torque (8) and (7) is below a predetermined value, the drying process begins. During the drying process, the vacuum pump 39 is left in an idle state for a while. During this idle operation, outside air is drawn in through the gas inlet 15a of the vacuum pump 15, passes through the gas flow path of the vacuum pump 15, and is then discharged through the gas outlet 15b of the vacuum pump 15. The outside air discharged from the gas outlet 15b then flows through the drain pipe 42A, the first port 35a, the third port 35c, the drain pipe 42B, and the vacuum pump 39, drying the inside of the gas flow path. The drying operation takes approximately two hours. During the drying operation, inert gas is flowed from the inert gas introduction unit 50 into the oil boxes 27 and 28 to dry the interiors of the oil boxes 27 and 28.

[0160] (9) Furthermore, when the cleaning and drying operations of the vacuum pump 15 are completed, the control unit 32 closes the on / off adjustment valve 53 of the inert gas introduction unit 50 to stop the introduction of the inert gas into the oil box 27 and the oil box 28. Then, the inert gas supply piping 52 is removed from the vacuum pump 15. Next, the water supply piping 41 is removed from the spray nozzle 54, and the drain piping 42A is removed from the gas outlet 15b of the vacuum pump 15. Furthermore, by connecting the gas exhaust piping 18 to the gas outlet 15b of the vacuum pump 15 that has been cleaned, the exhaust gas treatment device can be restored to a state similar to that shown in FIG.

[0161] Therefore, according to the vacuum exhaust system of this embodiment, by connecting the water supply pipe 41 leading to the cleaning liquid storage tank 36 to the spray nozzle 54, the cleaning liquid in the cleaning liquid storage tank 36 can be used to clean the vacuum pump 15.

[0162] Furthermore, the present invention can be modified or combined in various ways without departing from the spirit of the present invention, and it is natural that the present invention covers such modifications and combinations. [Explanation of symbols]

[0163] 15: Vacuum pump 27, 28: Oil box 31: Cleaning unit 36: Cleaning liquid storage tank (cleaning liquid storage section) 37: Cleaning liquid introduction pump (cleaning liquid introduction part) 39: Vacuum pump (cleaning liquid removal pump) 45: Cart 50: Inert gas introduction unit 54: Spray nozzle (cleaning liquid introduction part) 56: Poly tank (cleaning liquid storage section) G1: Gas

Claims

1. a vacuum pump for discharging the process gas containing the condensable gas or oxidized dust; a cleaning liquid introduction section that introduces a cleaning liquid into the gas flow path of the vacuum pump to remove deposits of the process gas accumulated in the gas flow path; a cleaning liquid removal pump that sucks and discharges the cleaning liquid in the gas flow path from an exhaust side of the gas flow path; A vacuum pumping system comprising:

2. Further provided is a cleaning liquid storage section that stores the cleaning liquid, 2. The vacuum pumping system according to claim 1, wherein the cleaning liquid in the cleaning liquid reservoir is introduced into the gas flow path from an exhaust side of the gas flow path.

3. 2. The vacuum pumping system according to claim 1, wherein the cleaning liquid is introduced from the intake side of the gas flow path by the cleaning liquid introduction part.

4. Further provided is a cleaning liquid storage section that stores the cleaning liquid, 4. The vacuum pumping system according to claim 3, wherein the cleaning liquid in the cleaning liquid reservoir is introduced into the gas flow path from an intake side of the gas flow path.

5. 2. The vacuum pumping system according to claim 1, wherein the cleaning liquid is water containing either microbubbles or ultrafine bubbles, or pure water.

6. 2. The vacuum pumping system according to claim 1, wherein the cleaning liquid is an acidic or alkaline cleaning liquid.

7. 2. The vacuum pumping system according to claim 1, further comprising an inert gas introduction unit that introduces an inert gas into an oil box that houses a drive unit and a bearing unit of the vacuum pump, and creates a positive pressure inside the oil box through the gas flow path.

8. 2. The vacuum pumping system of claim 1, wherein the vacuum pump is a positive displacement vacuum pump.

9. 1. A method for cleaning a vacuum pump that exhausts a process gas containing condensable gases or oxidized dust, comprising the steps of: introducing a cleaning liquid into a gas flow path of the vacuum pump to remove deposits of the process gas accumulated in the gas flow path; a step of sucking and discharging the cleaning liquid in the gas flow path from an exhaust side of the gas flow path by a cleaning liquid removal pump; drying the gas flow path; A method for cleaning a vacuum pump, comprising:

10. 10. The method for cleaning a vacuum pump according to claim 9, further comprising the step of introducing an inert gas into an oil box that houses a drive unit and a bearing unit of the vacuum pump, and creating a positive pressure in the oil box from the gas flow path, before the step of introducing the cleaning liquid into the gas flow path.

11. 10. The method for cleaning a vacuum pump according to claim 9, further comprising the step of driving the vacuum pump between the step of introducing the cleaning liquid into the gas flow path and the step of discharging the cleaning liquid from the gas flow path.

12. 10. The method for cleaning a vacuum pump according to claim 9, further comprising the step of driving the vacuum pump between the step of discharging the cleaning liquid from the gas flow path and the step of drying the gas flow path.

13. A cleaning unit for cleaning a gas flow path of a vacuum pump that discharges a process gas containing condensable gas or oxidized dust, comprising: a cleaning liquid introduction section that introduces a cleaning liquid into the gas flow path to remove deposits of the process gas that have accumulated in the gas flow path; a cleaning liquid removal pump that sucks and discharges the cleaning liquid in the gas flow path from an exhaust side of the gas flow path; A cleaning unit comprising:

14. Further provided is a cleaning liquid storage section that stores the cleaning liquid, 14. The cleaning unit according to claim 13, wherein the cleaning liquid reservoir, the cleaning liquid introduction section, and the cleaning liquid removal pump are mounted on a portable cart.

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