Steam cleaning reduced pressure drying apparatus

Abstract

The present application provides a steam cleaning and decompression drying device capable of increasing the number of workpieces processed per unit time while suppressing the cost of the device. It includes: multiple vacuum tanks (1st vacuum tank and 2nd vacuum tank); 1 vacuum pump; an exhaust pipe including a main exhaust pipe connected to the air inlet of the vacuum pump and multiple branch exhaust pipes (1st branch exhaust pipe and 2nd branch exhaust pipe) branched from the main exhaust pipe and each connected to one of the multiple vacuum tanks; multiple exhaust pipe on-off valves (1st exhaust pipe on-off valve and 2nd exhaust pipe on-off valve) each provided in one of the multiple branch exhaust pipes; an on-off valve control unit that controls the multiple exhaust pipe on-off valves to be individually closed or opened; a steam generation unit connected to each of the multiple vacuum tanks; an ejector connected to each of the multiple vacuum tanks; and a condensing mechanism (ejector-side condenser) provided between each of the multiple vacuum tanks and the ejector to condense and liquefy the steam.

Description

[0001] This application is a divisional application of the application filed on January 27, 2021, with application number 202110108546.9 and invention title "Steam Cleaning and Pressure Reduction Drying Device". Technical Field

[0002] This invention relates to a steam cleaning and depressurization drying apparatus for drying workpieces under reduced pressure after cleaning them with steam of a cleaning solution. Background Technology

[0003] In the past, steam cleaning and depressurization drying equipment was used whereby the workpiece was cleaned with steam obtained by vaporizing the cleaning fluid, and then depressurized drying was performed to remove the cleaning fluid adhering to the workpiece.

[0004] Regarding the steam cleaning and depressurization drying apparatus described in Patent Document 1, the workpiece is first placed in a vacuum tank. A vacuum pump is then used to reduce the pressure within the vacuum tank, and steam for the cleaning solution is introduced into the vacuum tank. The steam liquefies upon contact with the surface of the low-temperature workpiece, thus cleaning the surface with the cleaning solution (steam cleaning). However, if the pressure within the vacuum tank increases due to the introduction of steam (vacuum degree decreases), the boiling point of the cleaning solution rises, and the steam liquefies before contacting the workpiece surface, thus reducing the efficiency of steam cleaning. Therefore, when the pressure within the vacuum tank rises to a predetermined upper limit, the steam supply is temporarily stopped. Then, the vacuum pump is used to reduce the pressure within the vacuum tank to a predetermined lower limit, and the steam supply is resumed. By repeatedly performing this steam supply and depressurization operation, continuous steam cleaning of the workpiece becomes possible.

[0005] On the other hand, during continuous steam cleaning, the steam exchanges heat with the workpiece, heating it up. Since the steam ceases to liquefy when the workpiece is sufficiently heated, the steam cleaning process ends at that point.

[0006] After the steam cleaning process is completed, the pressure inside the vacuum tank is restored to atmospheric pressure, liquefying the steam as much as possible, and the liquefied cleaning solution is discharged from the vacuum tank. Then, a vacuum pump is used to rapidly reduce the pressure inside the vacuum tank. This causes the cleaning solution adhering to the surface of the workpiece to boil and vaporize, drying the surface (reduced pressure drying). Furthermore, as mentioned above, the reason for draining the cleaning solution accumulated at the bottom of the vacuum tank before the reduced pressure drying process is to prevent the cleaning solution from vaporizing and reducing the efficiency of the reduced pressure drying.

[0007] Patent Document 1 describes a steam cleaning and depressurization drying apparatus with only one vacuum chamber. In contrast, Patent Document 2 describes a steam cleaning and depressurization drying apparatus with multiple vacuum chambers and a number of vacuum pumps equal to the number of vacuum chambers, with one vacuum pump connected to each vacuum chamber. Using this steam cleaning and depressurization drying apparatus, steam cleaning and depressurization drying can be performed simultaneously in multiple vacuum chambers, increasing the number of workpieces processed per unit time compared to the steam cleaning and depressurization drying apparatus with only one vacuum chamber.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2011-251263

[0011] Patent Document 2: Japanese Patent Application Publication No. 2001-000930 Summary of the Invention

[0012] The problem the invention aims to solve

[0013] Since vacuum pumps are among the more expensive components of a steam cleaning and depressurization drying apparatus, the cost of the apparatus would increase if multiple vacuum pumps were used as described in Patent Document 2.

[0014] The problem to be solved by the present invention is to provide a steam cleaning and depressurization drying apparatus that can increase the number of workpieces processed per unit time while suppressing the cost of the apparatus.

[0015] Solution for solving the problem

[0016] The steam cleaning and depressurization drying apparatus of the present invention, which was completed to solve the above-mentioned problems, is characterized in that it comprises:

[0017] Multiple vacuum chambers;

[0018] 1 vacuum pump;

[0019] The exhaust pipe includes a main exhaust pipe connected to the air inlet of the vacuum pump and multiple branch exhaust pipes branching from the main exhaust pipe and connected to each of the plurality of vacuum chambers.

[0020] Multiple exhaust pipe opening and closing valves, one of each of the multiple branch exhaust pipes;

[0021] The valve control unit controls the individual closing or opening of the plurality of exhaust pipe valves;

[0022] A steam generation unit, which is connected to the plurality of vacuum tanks respectively;

[0023] Injectors, which are respectively connected to the plurality of vacuum chambers; and

[0024] A condensation mechanism is provided between each of the plurality of vacuum tanks and the ejector to condense and liquefy the vapor.

[0025] Furthermore, the steam cleaning and depressurization drying apparatus of the present invention can either have one steam generating unit shared by multiple vacuum chambers, or each vacuum chamber can have its own steam generating unit. Similarly, the steam cleaning and depressurization drying apparatus of the present invention can either have one ejector and / or condenser mechanism shared by multiple vacuum chambers, or each vacuum chamber can have its own ejector and / or condenser mechanism.

[0026] In the steam cleaning and depressurization drying apparatus of the present invention, steam cleaning and depressurization drying processes are performed in multiple vacuum chambers. During the steam cleaning process, steam is supplied to the vacuum chambers from the steam generation unit while exhaust gas is continuously discharged from the vacuum chambers using an ejector (not a vacuum pump). A condensation mechanism is used to liquefy the steam of the cleaning liquid contained in the exhaust gas, thereby promoting a pressure drop. This maintains the pressure within the vacuum chambers below a predetermined upper limit. This upper limit is appropriately set to a pressure that prevents the steam from liquefying before contacting the surface of the workpiece. Generally, the pressure to be maintained during steam cleaning is higher than the pressure to be achieved during depressurization drying, which can be achieved by combining the ejector and the condensation mechanism.

[0027] During the vacuum drying process, a vacuum pump rapidly exhausts air from the vacuum chamber at a lower pressure (higher vacuum) than when using an ejector and condenser mechanism. Here, the opening and closing valves of each exhaust pipe are individually controlled by the opening and closing valve control unit, staggering the timing of vacuum drying for each vacuum chamber, thus enabling vacuum drying to be performed in only one of the multiple vacuum chambers at each time. For example, the opening and closing valve control unit opens the exhaust pipe opening and closing valve of the branch exhaust pipe connected to the vacuum chamber where vacuum drying is performed, and closes the other exhaust pipe opening and closing valves. Furthermore, by sequentially switching the vacuum chambers with open exhaust pipe opening and closing valves, vacuum drying is performed sequentially in each vacuum chamber. Therefore, for the steam cleaning vacuum drying apparatus of the present invention, since the number of workpieces processed per unit time can be increased by using multiple vacuum chambers while only one vacuum pump is required, the cost of the apparatus can be reduced.

[0028] In this case, the steam cleaning and depressurization drying apparatus of the present invention does not use a vacuum pump during steam cleaning, so the steam discharged from the vacuum tank during steam cleaning does not flow into the vacuum pump. This also prevents some of the steam from liquefying in the vacuum pump and thus putting a load on the vacuum pump.

[0029] The steam cleaning and depressurization drying apparatus of the present invention can be structured such that the on / off valve control unit further controls the operation as follows: When steam cleaning is to begin in each of the plurality of vacuum chambers, while vacuum chambers other than the one to be steam cleaned are not undergoing depressurization drying, the exhaust pipe on / off valve of the branch exhaust pipe connected to the vacuum chamber to be steam cleaned is opened for a predetermined time. After this predetermined time, with the exhaust pipe on / off valve closed, steam is supplied to the vacuum chamber from the steam generation unit while exhaust is continuously vented from the vacuum chamber using an assembly combining an ejector and a condenser mechanism.

[0030] Therefore, compared to using only a combination of an ejector and a condenser for venting, the pressure inside the vacuum tank during steam cleaning can be reduced more quickly. This results in a shorter steam cleaning process time.

[0031] The steam cleaning and depressurization drying apparatus of the present invention can be structured as follows:

[0032] The steam cleaning and pressure-reducing drying device also has an atmospheric pressure release valve in each of the plurality of vacuum tanks, which opens the pressure inside the vacuum tank to atmospheric pressure.

[0033] The opening and closing valve control unit performs the following control on the multiple vacuum tanks respectively: after the steam cleaning treatment is completed, the atmospheric pressure opening valve located in the vacuum tank is opened, and then the atmospheric pressure opening valve is closed. On this basis, the exhaust pipe opening and closing valve located on the branch exhaust pipe connected to the vacuum tank is opened.

[0034] By bringing the pressure in the vacuum tank to atmospheric pressure after the steam cleaning process, the residual steam in the vacuum tank can be liquefied, preventing steam from flowing into the vacuum pump during the subsequent depressurization drying process. Therefore, it is possible to prevent some steam from liquefying in the vacuum pump and thus reducing its load. Furthermore, it reduces the amount of cleaning fluid that needs to be discharged from the vacuum tank, shortening the time required for the depressurization drying process.

[0035] On the other hand, the steam cleaning and depressurization drying apparatus of the present invention can be structured as follows:

[0036] The steam cleaning and depressurization drying device also has a vacuum pump-side condensation mechanism in either the exhaust pipe and the second exhaust pipe connected to the exhaust side of the vacuum pump, or both.

[0037] The on / off valve control unit performs the following control on the multiple vacuum tanks respectively: after the steam cleaning process is completed, instead of making the vacuum tank reach atmospheric pressure, the exhaust pipe on / off valve of the branch exhaust pipe connected to the vacuum tank is opened.

[0038] By performing depressurized drying without raising the pressure inside the vacuum chamber to atmospheric pressure after steam cleaning, the amount of gas that needs to be discharged from the vacuum chamber during depressurized drying is reduced compared to the case where atmospheric pressure is raised (i.e., atmospheric air is introduced into the vacuum chamber). This improves the recovery rate of cleaning fluid vapor contained in the discharged gas at the vacuum pump-side condenser. Therefore, cleaning fluid consumption can be suppressed. Furthermore, the amount of cleaning fluid vapor discharged from the second exhaust pipe can be reduced, minimizing adverse environmental impacts.

[0039] The steam cleaning and depressurization drying apparatus of the present invention can be structured such that the injector uses a liquid of the same kind as the liquid formed by liquefying the steam generated in the steam generating section as the driving fluid.

[0040] Therefore, liquid derived from steam recovered from the vacuum tank during steam cleaning can be introduced into the ejector and used as its driving fluid. Furthermore, if the driving fluid of the ejector is increased, a portion of that driving fluid can be reused for cleaning the workpiece.

[0041] The effects of the invention

[0042] The steam cleaning and depressurization drying apparatus of the present invention can increase the number of workpieces processed per unit time by using multiple vacuum chambers, while suppressing the cost of the apparatus by setting the number of vacuum pumps to only one. Attached Figure Description

[0043] Figure 1 This is a schematic structural diagram illustrating one embodiment of the steam cleaning and depressurization drying apparatus of the present invention.

[0044] Figure 2 This is a diagram showing the pressure changes in the first and second vacuum chambers during the operation of the steam cleaning and depressurization drying apparatus of this embodiment.

[0045] Figure 3 This is a diagram showing the timing of the vacuum pump and ejector depressurizing and venting in the first and second vacuum chambers, respectively, for the steam cleaning, depressurizing, and drying apparatus of this embodiment.

[0046] Figure 4 This is a graph showing the pressure changes in the first and second vacuum tanks during the steam cleaning process of the comparative example steam cleaning and depressurization drying apparatus.

[0047] Figure 5 This is a diagram showing the pressure changes in the first and second vacuum chambers during another operation of the steam cleaning and depressurization drying apparatus of this embodiment.

[0048] Explanation of reference numerals in the attached figures

[0049] 10. Steam cleaning, pressure reducing, and drying device; 111. First vacuum tank; 112. Second vacuum tank; 1131, 1132. Cover of the vacuum tank; 12. Vacuum pump; 121. Second exhaust pipe; 13. Exhaust pipe; 130. Main exhaust pipe; 131. First branch exhaust pipe; 132. Second branch exhaust pipe; 140. On / off valve control unit; 141. First exhaust pipe on / off valve; 142. Second exhaust pipe on / off valve; 15. Steam generating unit; 151. Steam generating tank; 152. Heater; 153. Steam discharge pipe; 154. Three-way valve; 155. Steam flow path pipe; 1550. Main steam flow path pipe; 1551. First branch steam flow path pipe; 1552. Second branch steam flow path pipe; 1561. First steam on / off valve; 1562. Second steam on / off valve. 1571, First Atmospheric Opening Pipe; 1572, Second Atmospheric Opening Pipe; 1581, First Atmospheric Opening Valve; 1582, Second Atmospheric Opening Valve; 16, Ejector; 161, Circulation Flow Path; 162, Liquid Delivery Pump; 163, Drive Fluid Tank; 165, Ejector-Side Exhaust Pipe; 1650, Ejector-Side Main Exhaust Pipe; 1651, Ejector-Side First Branch Exhaust Pipe; 1652, Ejector-Side Second Branch Exhaust Pipe; 166, Ejector-Side Condenser (Condensation Mechanism); 1661, Steam Supply Pipe for Condensate Discharge; 1671, Ejector-Side First Exhaust Pipe Opening / Closing Valve; 1672, Ejector-Side Second Exhaust Pipe Opening / Closing Valve; 171, 172, Vacuum Pump-Side Condenser (Vacuum Pump-Side Condensation Mechanism); 18, Immersion Cleaning Tank; 181, Ultrasonic Vibrator. Detailed Implementation

[0050] use Figures 1-5 This invention describes the implementation of the steam cleaning and depressurization drying apparatus.

[0051] (1) Structure of the steam cleaning and depressurization drying apparatus as one embodiment of the present invention

[0052] Figure 1 This is a diagram showing a schematic structure of a steam cleaning and vacuum drying apparatus 10 as one embodiment of the present invention. The steam cleaning and vacuum drying apparatus 10 includes a first vacuum chamber 111 and a second vacuum chamber 112 (corresponding to the plurality of vacuum chambers described above), and a vacuum pump 12. Each of the first vacuum chamber 111 and the second vacuum chamber 112 has an opening at its upper part and is equipped with a cover 1131, 1132 that can be airtightly closed and is removable.

[0053] A first branch exhaust pipe 131 is connected to the first vacuum chamber 111, and a second branch exhaust pipe 132 is connected to the second vacuum chamber 112. Furthermore, a main exhaust pipe 130 is connected to the inlet side of the vacuum pump 12. The first branch exhaust pipe 131 and the second branch exhaust pipe 132 branch off from the main exhaust pipe 130. These first branch exhaust pipes 131, second branch exhaust pipes 132, and the main exhaust pipe 130 constitute the exhaust pipe 13.

[0054] A first exhaust pipe opening and closing valve 141 is provided in the first branch exhaust pipe 131, and a second exhaust pipe opening and closing valve 142 is provided in the second branch exhaust pipe 132. These first exhaust pipe opening and closing valves 141 and second branch exhaust pipes 132 are equivalent to the aforementioned multiple exhaust pipe opening and closing valves.

[0055] The steam cleaning, pressure reducing, and drying apparatus 10 also includes a steam generating unit 15. The steam generating unit 15 includes a steam generating tank 151 for storing cleaning fluid, a heater 152 for heating the steam generating tank 151, a steam discharge pipe 153 communicating with the steam generating tank 151, and a three-way valve 154. The steam discharge pipe 153 is connected to one of the three outflow inlets of the three-way valve 154. A main steam flow path 1550 of a steam flow path 155 is connected to one of the other two outflow inlets of the three-way valve 154. The steam flow path 155 includes the main steam flow path 1550 and a first branch steam flow path 1551 and a second branch steam flow path 1552 branching from the main steam flow path 1550. The first branch steam flow path 1551 is connected to a first vacuum chamber 111, and the second branch steam flow path 1552 is connected to a second vacuum chamber 112. A first steam on / off valve 1561 is provided in the first branch steam flow pipe 1551, and a second steam on / off valve 1562 is provided in the second branch steam flow pipe 1552.

[0056] A first atmospheric opening pipe 1571 is provided in the first branch steam flow pipe 1551, located between the first vacuum tank 111 and the first steam on / off valve 1561. One end of the first atmospheric opening pipe 1571 is connected to the first branch steam flow pipe 1551, and the other end is open to the atmosphere. A first atmospheric opening valve 1581 is provided in the first atmospheric opening pipe 1571. Similarly, a second atmospheric opening pipe 1572 is provided in the second branch steam flow pipe 1552, located between the second vacuum tank 112 and the second steam on / off valve 1562. One end of the second atmospheric opening pipe 1572 is connected to the second branch steam flow pipe 1552, and the other end is open to the atmosphere. A second atmospheric opening valve 1582 is provided in the second atmospheric opening pipe 1572.

[0057] The steam cleaning and pressure-reducing drying apparatus 10 also includes an ejector 16. The ejector 16 is located within a circulation path 161, which circulates a cleaning fluid of the same type as the cleaning fluid stored in the steam generation tank 151 of the steam generation section 15. The ejector 16 uses this cleaning fluid as its driving fluid. A delivery pump 162 and a driving fluid tank 163 are provided within the circulation path 161. The driving fluid (cleaning fluid) is stored in the driving fluid tank 163 and is continuously introduced into the ejector 16 by the delivery pump 162, and then returned from the ejector 16 to the driving fluid tank 163.

[0058] The air inlet of the injector 16 is connected to the first vacuum chamber 111 and the second vacuum chamber 112 via the injector-side exhaust pipe 165. The injector-side exhaust pipe 165 has an injector-side main exhaust pipe 1650 connected to the air inlet of the injector 16, an injector-side first branch exhaust pipe 1651 branching from the injector-side main exhaust pipe 1650, and an injector-side second branch exhaust pipe 1652. The injector-side first branch exhaust pipe 1651 is connected to the first vacuum chamber 111, and the injector-side second branch exhaust pipe 1652 is connected to the second vacuum chamber 112. An injector-side condenser (the aforementioned condensation mechanism) 166 is provided in the injector-side main exhaust pipe 1650 to liquefy the vapor of the cleaning fluid. The first branch exhaust pipe 1651 on the injector side is provided with an injector side first exhaust pipe opening and closing valve 1671, and the second branch exhaust pipe 1652 on the injector side is provided with an injector side second exhaust pipe opening and closing valve 1672.

[0059] The remaining outflow inlet of the three-way valve 154 of the steam generating unit 15 is connected to the ejector-side condenser 166 via a condensate discharge steam supply pipe 1661.

[0060] A vacuum pump-side condenser (the aforementioned vacuum pump-side condensing mechanism) 171 is provided on the main exhaust pipe 130 to liquefy the vapor of the cleaning fluid. Similarly, a vacuum pump-side condenser (as above) 172 is also provided on the second exhaust pipe 121 connected to the exhaust side of the vacuum pump 12.

[0061] The steam cleaning, pressure reducing, and drying apparatus 10 also includes an on / off valve control unit 140. The on / off valve control unit 140 controls the individual closing or opening of the first exhaust pipe on / off valve 141, the second exhaust pipe on / off valve 142, the first steam on / off valve 1561, the second steam on / off valve 1562, the first atmospheric vent valve 1581, the second atmospheric vent valve 1582, the ejector-side first exhaust pipe on / off valve 1671, and the ejector-side second exhaust pipe on / off valve 1672. Furthermore, the on / off valve control unit 140 controls the three-way valve 154 to switch between the flow path connecting the steam exhaust pipe 153 and the main steam flow path pipe 1550, and the flow path connecting the steam exhaust pipe 153 and the condensate discharge steam supply pipe 1661.

[0062] In addition, the steam cleaning and depressurization drying apparatus 10 also includes an immersion cleaning tank 18. The immersion cleaning tank 18 is connected to the drive fluid tank 163 and is used to immerse and clean the workpiece by immersing it in a cleaning liquid of the same type as the cleaning liquid stored in the steam generation tank 151 of the steam generation unit 15. An ultrasonic transducer 181 contacts the bottom of the outer side of the immersion cleaning tank 18.

[0063] (2) Operation of the steam cleaning and depressurization drying device in this embodiment

[0064] Reference Figure 2 and Figure 3 The operation of the steam cleaning and vacuum drying apparatus 10 of this embodiment will be explained. After the workpiece (hereinafter referred to as "workpiece 1") is subjected to immersion cleaning in the immersion cleaning tank 18, the steam cleaning and vacuum drying processes, which are performed as finishing cleaning, are carried out in the first vacuum tank 111 and the second vacuum tank 112. Since the immersion cleaning process is the same as usual, its description is omitted. The steam cleaning and vacuum drying processes will be described below.

[0065] First, with the first exhaust pipe on / off valve 141 and the second exhaust pipe on / off valve 142 closed, the vacuum pump 12 is operated. Then, with the first steam on / off valve 1561 and the second steam on / off valve 1562 closed, steam is generated in the steam generation tank 151 by heating the cleaning fluid in the steam generation tank 151 using the heater 152. The three-way valve 154 is switched to the flow path on the steam flow path pipe 155 side. Furthermore, the first atmospheric vent valve 1581 and the second atmospheric vent valve 1582, as well as the ejector-side first exhaust pipe on / off valve 1671 and the ejector-side second exhaust pipe on / off valve 1672, are also pre-closed.

[0066] Next, the cover 1131 of the first vacuum tank 111 is opened to house the workpiece 1 that has undergone immersion cleaning, and then the first vacuum tank 111 is sealed using the cover 1131. Based on this, the on / off valve control unit 140 sends a signal to open the first exhaust pipe on / off valve 141. As a result, the gas (atmosphere) inside the first vacuum tank 111 is discharged using the vacuum pump 12. Figure 2 This reduces the pressure in the first vacuum chamber 111. The pressure in the first vacuum chamber 111 is reduced for a predetermined time ( Figure 2 At times t0 to t1, the pressure in the first vacuum chamber 111 drops to the predetermined pressure P1 (initial decompression).

[0067] At this point, the ejector 16 is activated by starting the liquid delivery pump 162. Then, the on / off valve control unit 140 sends signals to the valves described later to close the first exhaust pipe on / off valve 141 and open the first steam on / off valve 1561 and the ejector-side first exhaust pipe on / off valve 1671, forming a flow path connecting the steam discharge pipe 153 and the main steam flow path pipe 1550 using the three-way valve 154. As a result, steam from the cleaning fluid is supplied from the steam generation unit 15 to the first vacuum tank 111 and discharged from the first vacuum tank 111 by the ejector 16. During the period from when steam is supplied to the first vacuum tank 111 to when it is discharged from the first vacuum tank 111, the steam liquefies upon contact with the surface of the low-temperature workpiece 1, cleans the surface with the cleaning fluid, and heats the workpiece 1 through heat exchange between the steam and the workpiece 1. The steam discharged from the first vacuum tank 111 liquefies in the ejector-side condenser 166. As a result, stress reduction is promoted.

[0068] Generally speaking, the pressure reduction capacity of the assembly consisting of ejector 16 and ejector-side condenser 166 is lower than that of vacuum pump 12. Therefore, after the steam supply and discharge using ejector 16 are started, the pressure in the first vacuum tank 111 gradually increases (vacuum level decreases) in the initial stage, but after a period of time, it becomes approximately constant under the condition of pressure P2, which is higher than pressure P1. Figure 2 This prevents the pressure inside the first vacuum tank 111 from rising excessively due to the introduction of steam, and suppresses the liquefaction of steam before it comes into contact with the surface of the workpiece 1 due to the rise in boiling point caused by the increase in pressure. At this time, it is not necessary to use the vacuum pump 12 to reduce the pressure inside the first vacuum tank 111 in order to suppress the liquefaction of the steam.

[0069] The steam discharged from the first vacuum tank 111 is liquefied in the ejector-side condenser 166 and recovered as a cleaning fluid. A portion of the steam remains undiluted in the ejector-side condenser 166 and reaches the ejector 16, where it is recovered into the drive fluid tank 163. Additionally, the cleaning fluid recovered in the ejector-side condenser 166 may overflow during the steam cleaning process and be recovered into the drive fluid tank 163.

[0070] After steam cleaning has been performed for a predetermined time (up to time t3), the valve control unit 140 sends a signal to close the first steam valve 1561 and open the first atmospheric pressure valve 1581. As a result, the pressure inside the first vacuum chamber 111 becomes atmospheric pressure (Pa). Figure 2 The boiling point of the cleaning fluid rises, causing the vapor remaining in the first vacuum tank 111 to liquefy. The liquefied cleaning fluid is recovered to the ejector-side condenser 166 via the ejector-side first branch exhaust pipe 1651 (drainage). After drainage is completed, the on / off valve control unit 140 sends a signal to close the first atmospheric open valve 1581.

[0071] During the steam cleaning process of workpiece 1 in the first vacuum tank 111, the immersion cleaning process of another workpiece (hereinafter referred to as "workpiece 2") is completed in the immersion cleaning tank 18. Then, workpiece 2 is placed in the second vacuum tank 112, and the second vacuum tank 112 is sealed with a cover 1132. The on / off valve control unit 140 sends a signal to open the second exhaust pipe on / off valve 142 at the time from the start of suction by the ejector 16 in the first vacuum tank 111 (time t1) to the start of the depressurization drying process described later (time t5) (time t2). As a result, the gas (atmosphere) in the second vacuum tank 112 is discharged by the vacuum pump 12, and the pressure in the second vacuum tank 112 is reduced to pressure P1 (initial depressurization). At this time, since the first vacuum tank 111 is depressurized by the ejector 16 and the ejector-side condenser 166 as described above, the vacuum pump 12 is only applied to the initial depressurization of the second vacuum tank 112. Next, the valve control unit 140 sends a signal to close the second exhaust pipe valve 142 and open the second steam valve 1562 and the ejector-side second exhaust pipe valve 1672 (time t4). Operations on the second vacuum tank 112 continue until the depressurization drying process at the first vacuum tank 111 begins (time t5). By opening the second steam valve 1562 and the ejector-side second exhaust pipe valve 1672, steam cleaning of the workpiece 2 begins within the second vacuum tank 112.

[0072] At time t5, after the steam cleaning process begins in the second vacuum tank 112, the valve control unit 140 sends a signal to close the first exhaust pipe valve 1671 on the ejector side and open the first exhaust pipe valve 141. This causes a rapid depressurization within the first vacuum tank 111 using a vacuum pump. Figure 2 The cleaning fluid adhering to the surface of workpiece 1 boils and vaporizes, drying the surface of workpiece 1 (reduced pressure drying treatment). At this time, since the second vacuum tank 112 is being depressurized using ejector 16 and ejector-side condenser 166, vacuum pump 12 is only used for reduced pressure drying treatment at the first vacuum tank 111. The vaporized cleaning fluid tends towards the vacuum pump 12 side and is liquefied and recovered in vacuum pump-side condensers 171 and 172.

[0073] After a predetermined time elapsed since the start of the vacuum drying process (up to time t6), the pressure in the first vacuum chamber 111 is sufficiently (in... Figure 2After the pressure (P0) drops (at time t6), the on / off valve control unit 140 sends a signal to close the first exhaust pipe on / off valve 141 and open the first atmospheric pressure valve 1581. As a result, the pressure inside the first vacuum chamber 111 becomes atmospheric pressure Pa, allowing the cover 1131 to be opened and the workpiece 1 to be removed. Using this operation, the steam cleaning and depressurized drying processes on the workpiece 1 are completed.

[0074] In the second vacuum tank 112, after the steam cleaning process has been completed for a predetermined time (up to time t8), the on / off valve control unit 140 sends a signal to close the second steam on / off valve 1562 and open the second atmospheric pressure valve 1582. This brings the pressure inside the second vacuum tank 112 to atmospheric pressure (Pa), causing the steam remaining in the second vacuum tank 112 to liquefy. The liquefied cleaning liquid in the second vacuum tank 112 is recovered to the ejector-side condenser 166 via the ejector-side second branch exhaust pipe 1652 (drainage). After drainage is completed, the on / off valve control unit 140 sends a signal to close the second atmospheric pressure valve 1582. Furthermore, at time t10, the on / off valve control unit 140 sends a signal to close the ejector-side second exhaust pipe on / off valve 1672 and open the second exhaust pipe on / off valve 142. This rapidly depressurizes the pressure inside the second vacuum tank 112, performing depressurization drying on the workpiece 2. After a predetermined time has elapsed, the on / off valve control unit 140 sends a signal to close the second exhaust pipe on / off valve 142 and open the second atmospheric pressure valve 1582. As a result, the pressure inside the second vacuum chamber 112 becomes atmospheric pressure (Pa), allowing the cover 1132 to be opened and the workpiece 2 to be removed. This operation completes the steam cleaning and depressurized drying process on the workpiece 2.

[0075] On the other hand, in the first vacuum tank 111, after the workpiece 1 is removed, during the steam cleaning process in the second vacuum tank 112, a new workpiece 1' is taken in (workpiece replacement), and initial depressurization is performed with the cover 1131 closed (time t7). During this initial depressurization, since the ejector 16 is used to exhaust air in the second vacuum tank 112 for steam cleaning, the vacuum pump 12 is only applied to this initial depressurization in the first vacuum tank 111. Then, at time t9, until the start of the depressurization drying process in the second vacuum tank 112, the initial depressurization performed by the vacuum pump 12 ends in the first vacuum tank 111, and the process transitions to steam cleaning accompanied by exhaust air using the ejector 16. Therefore, during the depressurization drying process in the second vacuum tank 112, the vacuum pump 12 is only applied to this process. The operation of processing workpiece 1' after the depressurization drying process in the first vacuum tank 111 is the same as the operation of processing workpiece 1.

[0076] In the second vacuum tank 112, after the steam cleaning and depressurized drying of workpiece 2 are completed, the new workpiece 2' is subjected to the same steam cleaning and depressurized drying process as workpiece 1'.

[0077] As described above, in the steam cleaning and depressurization drying apparatus 10 of this embodiment, since steam cleaning and depressurization drying are performed simultaneously between the first vacuum tank 111 and the second vacuum tank 112 at staggered start times, the number of workpieces processed per unit time can be increased compared to the case of using only one vacuum tank.

[0078] Furthermore, during the steam cleaning process, the vacuum pump 12 is used only before the process begins; afterwards, the vacuum pump 12 is not used, but instead the ejector 16 and the ejector-side condenser 166 are used to depressurize the vacuum tank. Then, while one of the first vacuum tanks 111 and the second vacuum tank 112 is depressurized using the ejector 16 and the ejector-side condenser 166 during the steam cleaning process, the other is subjected to depressurization drying using the vacuum pump 12. As a result, as... Figure 3 As shown, the timing of using vacuum pump 12 to depressurize the first vacuum chamber 111 is staggered from the timing of using vacuum pump 12 to depressurize the second vacuum chamber 112. Therefore, in this embodiment, the steam cleaning depressurization drying apparatus 10 only needs to be equipped with one vacuum pump.

[0079] In contrast, for conventional steam cleaning and depressurization drying devices that do not use ejectors, such as Figure 4 As shown, after the steam cleaning process begins and the pressure inside the vacuum tank reaches a predetermined value P2, it is necessary to use a vacuum pump to remove the steam from the vacuum tank until the pressure drops to P1 (< P2). Therefore, even if the timing of the steam cleaning process and the reduced pressure drying process are staggered between the two vacuum tanks, when steam cleaning is performed in one vacuum tank and reduced pressure drying is performed in another vacuum tank, the period during which steam is removed from the vacuum tank during the steam cleaning process ( Figure 4 (As indicated by reference numeral A in the attached diagram) Vacuum pumps must also be used in both vacuum chambers. Therefore, for conventional steam cleaning and depressurization drying apparatuses with multiple vacuum chambers, a vacuum pump needs to be installed in each vacuum chamber.

[0080] Therefore, the steam cleaning and depressurization drying apparatus 10 of this embodiment can reduce the number of vacuum pumps compared to conventional steam cleaning and depressurization drying apparatuses (such as the apparatus described in Patent Document 2) which have multiple vacuum chambers, thereby reducing the cost of the apparatus.

[0081] After the series of actions described above are completed, the three-way valve 154 is switched from the flow path on the steam flow path pipe 155 side to the flow path on the condensate discharge steam supply pipe 1661 side. As a result, steam is supplied from the steam generation tank 151 to the ejector-side condenser 166, and the cleaning fluid recovered in the ejector-side condenser 166 is squeezed out by the steam. The cleaning fluid squeezed out from the ejector-side condenser 166 is recovered to the drive fluid tank 163 via the ejector-side main exhaust pipe 1650, the ejector 16, and the circulation flow path 161. In the drive fluid tank 163, when the amount of cleaning fluid serving as the drive fluid exceeds a predetermined storage capacity, the excess cleaning fluid is supplied to the immersion cleaning tank 18.

[0082] (3) Another example of the operation of the steam cleaning and depressurization drying apparatus of this embodiment

[0083] In the operation of the steam cleaning and vacuum drying apparatus 10 described above, the following drainage process is performed: after the steam cleaning process is completed and before the vacuum drying process, the atmospheric opening valve (first atmospheric opening valve 1581 or second atmospheric opening valve 1582) is opened, so that the vacuum tanks (first vacuum tank 111 and second vacuum tank 112) reach atmospheric pressure, thereby liquefying and discharging the vapor remaining in the vacuum tanks. Alternatively, it can be done as follows... Figure 5 As shown, in each of the first vacuum tank 111 and the second vacuum tank 112, after the steam cleaning process is completed (time t8), the vacuum tank is not made to reach atmospheric pressure, but is depressurized and dried by depressurizing the vacuum tank.

[0084] Therefore, by reducing pressure without allowing it to flow into the atmosphere, the amount of gas that should be discharged from the vacuum chamber during the vacuum drying process can be reduced, thus improving the vapor recovery rate of the cleaning fluid at the vacuum pump-side condensers 171 and 172. This reduces the consumption of the cleaning fluid. Simultaneously, it reduces the amount of cleaning fluid vapor discharged from the second exhaust pipe 121 to the outside, minimizing adverse environmental impacts.

[0085] (4) Variations

[0086] This invention is not limited to the above-described embodiments and can be modified in various ways. For example, in the above-described embodiments, two vacuum chambers are provided, but it is also possible to provide three or more vacuum chambers, with only one vacuum pump connected to each of these three or more vacuum chambers. Alternatively, for example, four vacuum chambers and two vacuum pumps can be provided, with one vacuum pump connected to every two vacuum chambers, etc., with multiple vacuum chambers and vacuum pumps provided respectively (wherein, the number of vacuum chambers is greater than the number of vacuum pumps).

[0087] In the above embodiment, only one steam generating unit 15 is provided overall. However, it is also possible to provide one steam generating unit 15 for each vacuum chamber, resulting in multiple steam generating units 15. Furthermore, in the above embodiment, only one ejector 16 and one ejector-side condenser 166 are provided overall. However, it is also possible to provide one or both of the above-mentioned ejector 16 and ejector-side condenser 166 for each vacuum chamber, resulting in multiple ejectors 16 and ejector-side condensers 166. Since these steam generating units 15, ejectors 16, and ejector-side condensers 166 are less expensive than the vacuum pump 12, their impact on the cost of the device is smaller than that of the vacuum pump 12.

[0088] In the above embodiment, a cleaning fluid is used as the working fluid of the injector 16, but liquids or gases other than cleaning fluids can also be used as the working fluid.

[0089] Furthermore, a cooling mechanism for cooling the ejector-side exhaust pipe 165 may be provided in addition to the ejector-side condenser 166, or this cooling mechanism may be provided instead of the ejector-side condenser 166. Such a cooling mechanism also functions as a condensation mechanism for condensing and liquefying the vapor discharged from the vacuum tank by the ejector 16. As a cooling mechanism, for example, a cooling coil formed by winding a pipe for refrigerant flow around the ejector-side exhaust pipe 165, or a cooling fan that blows air onto the surface of the ejector-side exhaust pipe 165 can be used. Furthermore, a cooling mechanism for cooling the exhaust pipe 13 and the second exhaust pipe 121 may be provided in addition to the vacuum pump-side condensers 171 and 172, or this cooling mechanism may be provided instead of the vacuum pump-side condensers 171 and 172. In addition, only one of the vacuum pump-side condensers 171 and 172 may be provided, and embodiments omitting the vacuum pump-side condensers 171 and 172 are also included in the present invention.

[0090] In the above embodiment, one immersion cleaning tank 18 is provided, but two or more immersion cleaning tanks may also be provided. Alternatively, the apparatus of the present invention may not include an immersion cleaning tank, and a separate immersion cleaning device may be used instead.

Claims

1. A steam cleaning and depressurization drying device, characterized in that, The steam cleaning and pressure-reducing drying device includes: Multiple vacuum chambers; A steam generation unit, which is connected to the plurality of vacuum tanks respectively; Steam on / off valves are respectively disposed between each of the plurality of vacuum tanks and the steam generating unit; 1 vacuum pump; The exhaust pipe includes a main exhaust pipe connected to the air inlet of the vacuum pump and branch exhaust pipes branching from the main exhaust pipe and connected to each of the plurality of vacuum chambers respectively. Exhaust pipe opening and closing valves are respectively installed on each branch exhaust pipe of the multiple branch exhaust pipes; Injectors, which are respectively connected to the plurality of vacuum tanks; The exhaust pipe opening and closing valves on the injector side are respectively located between each of the plurality of vacuum tanks and the injector; A condensation mechanism, located between the on / off valve of the exhaust pipe on each of the injectors and the injector, condenses and liquefies the vapor; and The valve control unit sequentially switches between open and closed exhaust pipe valves while performing the following control: opening one of the exhaust pipe valves and closing the others; closing the steam valve between the vacuum chamber corresponding to the open exhaust pipe valve and the steam generation unit, and closing the ejector-side exhaust pipe valve between the vacuum chamber and the ejector, thereby performing depressurization drying in the vacuum chamber; and opening at least one steam valve between the vacuum chamber corresponding to the closed exhaust pipe valve and the steam generation unit, and opening the ejector-side exhaust pipe valve between the vacuum chamber and the ejector, thereby performing steam cleaning in the vacuum chamber.

2. The steam cleaning and pressure-reducing drying apparatus according to claim 1, characterized in that, The valve control unit also performs the following control: in each of the plurality of vacuum tanks, when steam cleaning is to be started, at a time when vacuum tanks other than the one to be steam cleaned have not undergone depressurization drying, the valve on the exhaust pipe of the branch exhaust pipe connected to the vacuum tank to be steam cleaned is opened for a predetermined time.

3. The steam cleaning and depressurization drying apparatus according to claim 1 or 2, characterized in that, The steam cleaning and pressure-reducing drying device also has an atmospheric pressure release valve in each of the plurality of vacuum tanks, which opens the pressure inside the vacuum tank to atmospheric pressure. The opening and closing valve control unit performs the following control on the multiple vacuum tanks respectively: after the steam cleaning treatment is completed, the atmospheric pressure opening valve located in the vacuum tank is opened, and then the atmospheric pressure opening valve is closed. On this basis, the exhaust pipe opening and closing valve located on the branch exhaust pipe connected to the vacuum tank is opened.

4. The steam cleaning and depressurization drying apparatus according to claim 1 or 2, characterized in that, The steam cleaning and depressurization drying device also has a vacuum pump-side condensation mechanism in either the exhaust pipe and the second exhaust pipe connected to the exhaust side of the vacuum pump, or both. The on / off valve control unit performs the following control on the multiple vacuum tanks respectively: after the steam cleaning process is completed, instead of making the vacuum tank reach atmospheric pressure, the exhaust pipe on / off valve of the branch exhaust pipe connected to the vacuum tank is opened.

5. The steam cleaning and depressurization drying apparatus according to claim 1 or 2, characterized in that, The injector uses a liquid of the same type as the liquid formed by liquefying the steam generated in the steam generation section as the driving fluid.

6. The steam cleaning and depressurization drying apparatus according to claim 1 or 2, characterized in that, The steam generating unit includes a steam generating tank for storing cleaning fluid, a heater for heating the steam generating tank, and a steam discharge pipe connected to the steam generating tank. The steam generating unit also includes: A three-way valve has a first outflow inlet, a second outflow inlet, and a third outflow inlet. The steam discharge pipe is connected to the third outflow inlet. The three-way valve switches between the flow path connecting the first outflow inlet and the third outflow inlet and the flow path connecting the second outflow inlet and the third outflow inlet. A vapor flow path pipe on the vacuum tank side, which connects the first outflow inlet to each of the plurality of vacuum tanks; and A steam supply pipe on the condenser side is connected to the second outflow inlet and the condenser.

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