Suction filtration device

Abstract

To provide a sucking and filtering device capable of rapidly detecting the completion of sucking and filtering when the filtering of liquid w1 stored in a vessel 1 is all completed.SOLUTION: Provided are a vessel 1 that stores liquid w1, a filter 6 that is installed at a drain outlet of the vessel 1 and filters out solid matter contained in the liquid w1, a suction-pump P1 that suctions the liquid w1, a pipeline P1 that directly or indirectly connects the drain outlet and a suction inlet of the suction-pump L1, a detection unit (a pressure sensor 4 and an airflow sensor 7) that detects an inflow of air into the pipeline L1, and a control unit 5 that determines that filtration of the liquid L1 in the vessel 1 has ended when an inflow of air into the pipeline is detected. w1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a suction filtering device that suction-filters a liquid stored in a container to collect solid matter in the liquid. [Background technology]

[0002] For example, suction filtration devices are used to extract nucleic acids, which are genetic material, from microorganisms and viruses associated with infectious diseases contained in sewage (see, for example, Patent Document 1). Suction filtration devices are equipped with a container for storing liquids such as sewage, and by filtering the sewage stored in the container using a filter, solid matter including proteins, microorganisms, nucleic acids, etc. is collected.

[0003] Specifically, a filter is installed at the drain outlet of a container storing sewage, and the drain outlet is connected to the suction port of a suction pump via a pipe. The suction pump is driven to create negative pressure in the pipe, and the sewage in the container is sucked and filtered, allowing solid matter adhering to the filter to be collected, and ultimately proteins, microorganisms, nucleic acids, etc. contained in the solid matter to be collected.

[0004] In such a suction filtration device, if the suction pump continues to operate after the suction filtration of the liquid in the container has been completed, the solid matter adhering to the filter may dry out and become unusable as a sample. Therefore, once the suction filtration of the liquid has been completed, it is desirable to quickly close the conduit and stop the suction pump. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-155697 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventional suction filtration devices do not have a function to detect when all of the liquid in the container has been filtered. Therefore, the operator visually monitors the amount of liquid remaining in the container and stops the suction pump when all of the liquid has been filtered. However, the time required for suction filtration varies depending on the amount of liquid stored in the container and the amount of solids contained in the liquid. This makes it difficult to determine when suction filtration will finish, making it difficult for the operator to stop the suction pump in a timely manner to coincide with the completion of suction filtration.

[0007] The present invention has been made to solve these conventional problems, and its purpose is to provide a suction filtration device that can quickly detect the end of suction filtration when all of the liquid stored in the container has been filtered. [Means for solving the problem]

[0008] In order to achieve the above object, the suction filtration device of the present disclosure comprises a container for storing liquid, a filter installed at the drain outlet of the container and filtering out solid matter contained in the liquid, a pump for sucking up the liquid, a pipeline directly or indirectly connecting the drain outlet and the suction port of the pump, a detection unit for detecting air flowing into the pipeline, and a determination unit for determining that filtration of the liquid in the container has been completed when air flowing into the pipeline is detected.

[0009] Another disclosed suction filtration device includes a container having a sealed structure for storing liquid, a filter installed at the drain outlet of the container and filtering out solid matter contained in the liquid, a pump for sucking the liquid, a pipeline directly or indirectly connecting the drain outlet to the suction port of the pump, a cylinder consisting of a tube connected to the lid of the container and a piston that slides in accordance with the air pressure inside the tube, a measuring unit that measures the sliding position of the piston, and a determining unit that determines that filtration of the liquid inside the container has been completed when the air pressure inside the tube decreases and the sliding position of the piston reaches a predetermined position. [Effects of the Invention]

[0010] According to the present invention, it is possible to quickly detect the end of suction filtration when the filtration of all the liquid stored in the container has been completed. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram that schematically shows the configuration of a suction filtration device according to a first embodiment. [Figure 2] FIG. 2 is a flowchart showing the processing procedure of the suction filtering device according to the first embodiment. [Figure 3A] FIG. 3A is a first sub-part of a flowchart showing the detailed processing procedure of the filtering end determination processing shown in FIG. [Figure 3B] FIG. 3B is a second sub-part of the flowchart showing the detailed processing procedure of the filtering end determination processing shown in FIG. [Figure 3C] FIG. 3C is a third sub-part of the flowchart showing the detailed processing procedure of the filtering termination determination processing shown in FIG. [Figure 4] FIG. 4 is an explanatory diagram that schematically shows the configuration of a suction filtering device according to a modified example of the first embodiment. [Figure 5] FIG. 5 is an explanatory diagram that schematically shows the configuration of a suction filtering device according to the second embodiment. [Figure 6] FIG. 6 is a flowchart showing the processing procedure of the suction filtering device according to the second embodiment. [Figure 7] FIG. 7 is a flowchart showing the detailed processing procedure of the filtering end determination processing shown in FIG. [Figure 8] FIG. 8 is an explanatory diagram that schematically shows the configuration of a suction filtering device according to the third embodiment. [Figure 9] FIG. 9 is a flowchart showing the processing procedure of the suction filtering device according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Explanation of the first embodiment] Fig. 1 is an explanatory diagram showing a schematic configuration of a suction filtration device according to the first embodiment. As shown in Fig. 1, the suction filtration device 101 according to the first embodiment includes a container 1, a trap bottle 2, a suction pump P1 (pump), a pressure sensor 4, a control unit 5, two solenoid valves SV1 and SV2, and pipelines L1 and L2.

[0013] The container 1 stores a liquid w1, such as sewage. A drain outlet is provided at the bottom of the container 1, and the drain outlet is provided with a filter 6 for filtering solid matter (e.g., suspended matter) contained in the liquid w1. The solid matter includes, for example, microorganisms and viruses related to infectious diseases. The filter 6 is made of, for example, glass fiber, and collects the solid matter contained in the liquid w1.

[0014] The drain outlet of the container 1 is connected to the trap bottle 2 via a conduit L1. The trap bottle 2 is connected to the suction port of the suction pump P1 via a conduit L2. The conduits L1 and L2 directly or indirectly connect the drain outlet of the container 1 to the suction port of the suction pump P1. "Directly connected" refers to connecting the container 1 to the trap bottle 2 via the conduit L1, as shown in FIG. 1. "Indirectly connected" refers to connecting the container 1 to the sealed container 22 and the trap bottle 2 via the conduit L1, as shown in FIG. 4 (modification) described later. Two solenoid valves SV1 and SV2 are installed on the path of the conduit L1. The trap bottle 2 is located between the conduit L1 and the suction port of the suction pump P1 and stores the liquid w1 that has passed through the filter 6.

[0015] A pressure sensor 4 is installed in the pipe L1 between the solenoid valves SV1 and SV2. The pressure sensor 4 measures the pressure in the pipe L1. The pressure sensor 4 outputs the measured pressure data to the control unit 5. Based on the pressure data, the control unit 5 detects that air has flowed into the pipe L1 based on the following two conditions (A) and (B), i.e., a predetermined pressure change.

[0016] (A) When the suction pump P1 finishes suctioning the liquid w1, the pressure in the pipeline L1 immediately rises, changing from negative to positive, and then drops back to negative. This pressure change is then detected to determine the completion of suction filtration. (B) When the suction pump P1 has finished suctioning the liquid w1, there is no sudden change in pressure at the time of completion, but the pressure in the pipeline L1 gradually increases and shifts to a positive pressure. Therefore, this pressure change is detected to detect the completion of suction filtration.

[0017] The control unit 5 determines that the suction is complete when one of the above conditions (A) and (B) is met.

[0018] The suction port of the suction pump P1 is connected to the discharge port of the container 1 via a conduit L2, a trap bottle 2, and a conduit L1. By driving the suction pump P1, the liquid w1 stored in the container 1 can be sucked. By sucking the liquid w1 with the suction pump P1, solids contained in the liquid w1 can be filtered by the filter 6. In addition, the liquid w1 after filtration can be stored in the trap bottle 2.

[0019] The control unit 5 controls the operation of the suction pump P1 and the opening and closing of the solenoid valves SV1 and SV2. The control unit 5 determines whether air has flowed into the conduit L1 based on the pressure in the conduit L1 detected by the pressure sensor 4. That is, once the liquid w1 in the container 1 is completely filtered by the suction pump P1, air then flows into the conduit L1. The inflow of air changes the pressure in the conduit L1 as shown in (A) or (B) above. The control unit 5 detects the inflow of air by observing a series of pressure changes based on the measurement results of the pressure sensor 4. That is, the control unit 5 functions as a determination unit that determines that the filtration of the liquid w1 in the container 1 has ended when the inflow of air into the conduit L1 is detected. The pressure sensor 4 also functions as a detection unit that detects the inflow of air into the conduit L1.

[0020] The control unit 5 determines that the filtration of the liquid w1 has ended when it detects that air has flowed into the pipeline L1. When the filtration of the liquid w1 stored in the container 1 has ended, the control unit 5 stops the suction pump P1. That is, after the filtration of the liquid w1 has ended, the control unit 5 closes the solenoid valve SV2 to prevent solid matter (e.g., suspended matter) adhering to the filter 6 from being exposed to the airflow. The control unit 5 also notifies the user by displaying the end of filtration on a display (not shown) or the like.

[0021] Next, the operation of the suction filtering device 101 according to the first embodiment will be described with reference to the flowcharts shown in Figures 2 and 3. As an initial setting, a liquid w1 (e.g., sewage) to be inspected is stored in a container 1. A filter 6 for filtering out solid matter is also installed at the drain outlet of the container 1.

[0022] First, in step S1 of FIG. 2, the control unit 5 starts the suction pump P1.

[0023] In step S2, the control unit 5 opens the solenoid valves SV1 and SV2, causing the suction pump P1 to start suctioning the liquid w1.

[0024] In step S3, the control unit 5 starts the suction pump P1 and then waits for a predetermined time (for example, 200 [msec]).

[0025] In step S4, the control unit 5 starts acquiring the pressure value detected by the pressure sensor 4. In this process, the control unit 5 acquires the pressure value from the pressure sensor 4 every 200 msec.

[0026] In step S5, the control unit 5 performs a filtering end determination process. Hereinafter, the detailed processing procedure of the filtering end determination process will be described with reference to the flowcharts shown in Figures 3A to 3C.

[0027] In step S51 of FIG. 3A, the control unit 5 waits for an arbitrary interval time (for example, 200 [msec]) to elapse.

[0028] In step S52, the control unit 5 acquires the AD conversion value of the pressure detected by the pressure sensor 4.

[0029] In step S53, the control unit 5 acquires the average value AV, the maximum value Pmax, and the minimum value Pmin of each AD conversion value from the AD conversion values of the pressure for the most recent 20 times. At this time, the average value AD at the first measurement is used as the peak hold average value. In the measurements after the second time, the average value AV(t - 1) at the previous measurement and the average value AV(t) of the current measurement are compared. If "AV(t)> AV(t - 1)", the peak hold average value is updated. That is, the maximum average value AV after the detection by the pressure sensor 4 is stored in the peak hold average value.

[0030] In step S54, the control unit 5 compares the average value AV(t - 1) at the previous measurement with the average value AV(t) of the current measurement. That is, it determines whether "AV(t)<AV(t - 1)". If "AV(t)<AV(t - 1))" (ST54; YES), the process proceeds to step S55. Otherwise (S54; NO), the process proceeds to step S56. That is, when the average value AV of the AD conversion value is decreasing, it indicates that the pressure in the pipeline L1 changes from negative pressure to positive pressure, and when it is increasing, it indicates that the pressure in the pipeline L1 changes from positive pressure to negative pressure.

[0031] In step S55, the control unit 5 increments the down count value CTd, making it "CTd = CTd + 1". Then, the process proceeds to step S57 shown in FIG. 3B.

[0032] In step S56, the control unit 5 resets the down count value CTd. Then, the process proceeds to step S57. That is, when the pressure detected by the pressure sensor 4 rises from negative pressure to positive pressure and the AD conversion value shows a downward trend, the down count value CTd is incremented, and when the downward trend ends, the down count value CTd is reset.

[0033] In step S57, the control unit 5 determines whether the decrease count value CTd is 5 or not. "CTd=5" is a preset threshold value, and may be another numerical value. If "CTd=5" is true (S57; YES), the process proceeds to step S58; if not (S57; NO), the process proceeds to step S59. That is, as indicated in the above-mentioned condition (A), when the suction of the liquid w1 is completed, the pressure in the conduit L1 may suddenly increase (i.e., the AD conversion value suddenly decreases), and the process of step S57 determines this pressure increase.

[0034] In step S58, the control unit 5 determines whether the value obtained by subtracting the minimum value from the peak hold (PH) average value exceeds a predetermined threshold value. That is, it determines whether "(PH average value) - (minimum value) > threshold value." If "(PH average value) - (minimum value) > threshold value" holds (S58; YES), the process proceeds to step S61; if not (S58; NO), the process proceeds to step S66.

[0035] In step S59, the control unit 5 determines whether the value obtained by subtracting the minimum value from the peak hold (PH) average value exceeds a predetermined threshold value. That is, it determines whether "(PH average value) - (minimum value) > threshold value." If "(PH average value) - (minimum value) > threshold value" holds (S59; YES), the process proceeds to step S60; if not (S59; NO), the process proceeds to step S66. That is, it is confirmed that "(PH average value) - (minimum value) > threshold value."

[0036] In step S60, the control unit 5 determines whether the time when the minimum value occurred is later than the time when the maximum value occurred. If the time when the minimum value occurred is later than the time when the maximum value occurred (S60; YES), the process proceeds to step S61; if not (S60; NO), the process proceeds to step S66. In this process, based on the AD conversion values ​​from the most recent 20 measurements, it is confirmed that the AD conversion value is on a downward trend, i.e., the pressure in the conduit L1 is on an upward trend. In other words, the fact that the minimum value is later than the maximum value means that the AD conversion value is decreasing and the pressure in the conduit L1 is increasing.

[0037] In step S61, the control unit 5 determines whether the number of times that the value obtained by subtracting the minimum value from the peak hold (PH) average value has exceeded the predetermined threshold is the first time. If it is the first time (S61; YES), the process proceeds to step S63; if not (S61; NO), the process proceeds to step S62.

[0038] In step S62, the control unit 5 determines whether or not the minimum value of the AD conversion value of the pressure sensor 4 has been updated. If it has been updated (S62; YES), the process proceeds to step S64; if not (S62; NO), the process proceeds to step S65.

[0039] In step S63, the control unit 5 determines that the suction filtration of the liquid w1 has ended. Then, the process proceeds to step S66 shown in FIG. 3C. That is, if the down count value CTd has reached five and the difference between the peak hold average value and the minimum value has exceeded the threshold, it is determined that the suction filtration has ended if this is the first time. Furthermore, even if the down count has not reached five, if the difference between the peak hold average value and the minimum value has exceeded the threshold and the maximum value of the AD conversion value has occurred before (at an earlier time than) the minimum value, it is determined that the suction filtration has ended if this is the first time.

[0040] In step S64, the control unit 5 updates the minimum value of the AD converted value of the pressure sensor 4. Thereafter, the process proceeds to step S66.

[0041] In step S65, the control unit 5 increments the upper limit count value Ctu to "CTu=CTu+1." After that, the process proceeds to step S66.

[0042] In step S66, the control unit 5 determines whether or not it has been determined in the processing of step S63 that suction filtration has been completed. If suction filtration has been completed (S66; YES), the processing proceeds to step S67; if not (S66; NO), the processing proceeds to step S68. That is, if the "pH average value - minimum value" exceeds the threshold value and the AD conversion value is on a downward trend (i.e., the pressure is on an upward trend), it is determined that filtration has been completed.

[0043] In step S67, the control unit 5 counts the number of times the filtration is completed and passes through, and then the process proceeds to step S68.

[0044] In step S68, the control unit 5 determines whether the number of passes has reached a specified number (for example, 20 times). If it has reached 20 times (S68; YES), the process proceeds to step S70; if not (S68; NO), the process proceeds to step S69.

[0045] In step S69, the control unit 5 determines whether the upper limit count value Ctu = 5. If "CTu = 5" (S69; YES), the process proceeds to step S70; if not (S69; NO), the process proceeds to step S71.

[0046] In step S70, the control unit 5 determines whether or not the minimum filtration time has been exceeded. The minimum filtration time is a time that is preset by the user. If the minimum filtration time has been exceeded (S70; YES), the process proceeds to step S72; if not (S70; NO), the process proceeds to step S71.

[0047] In step S71, the control unit 5 determines whether or not a timeout has occurred. If a timeout has occurred (S71; YES), the suction filtration process is terminated due to the timeout, and if not (S71; NO), the process returns to step S51 in Fig. 3A.

[0048] In step S72, the control unit 5 determines whether or not a timeout has occurred. If a timeout has occurred (S72; YES), the suction filtration process is terminated. If a timeout has not occurred (S72; NO), the suction filtration process is terminated normally. Thereafter, the process proceeds to step S6 in FIG. 2.

[0049] That is, if it is determined in the process of step S63 that filtration is complete, and this determination is made 20 times consecutively in the process of step S68, it is determined that suction filtration has been completed normally for all of the liquid w1 in the container 1. Also, even if the filtration completion determination is made less than 20 times, if the count value Ctu, which indicates a tendency for pressure to rise, reaches 5 times in step S69, it is determined that suction filtration has been completed normally.

[0050] In step S6 of FIG. 2, the control unit 5 closes the solenoid valves SV1 and SV2.

[0051] In step S7, the control unit 5 stops the suction pump P1. When the filtration of the liquid w1 stored in the container 1 is thus completed and the liquid w1 in the container 1 is depleted, the control unit 5 closes the solenoid valve SV2 and stops the suction pump P1, thereby completing the filtration.

[0052] In this way, in the suction filtration device 101 according to the first embodiment, solid matter in the liquid w1 is filtered by driving the suction pump P1, and nucleic acids, which are genetic material, can be extracted from, for example, infectious disease-related microorganisms and viruses contained in the solid matter. Furthermore, when filtration of the liquid w1 stored in the container 1 is completed and the liquid w1 in the container 1 is depleted, air flows into the conduit L1, causing a drop in pressure. The control unit 5 detects the change in pressure and determines the end of filtration. Therefore, when filtration of the liquid w1 is completed, the control unit 5 can immediately detect this, close the solenoid valves SV1 and SV2, and stop the suction pump P1. This prevents the solid matter filtered by the filter 6 from being exposed to airflow after filtration is completed, preventing the solid matter from drying out.

[0053] [Description of Modification of First Embodiment] Next, a modified example of the suction filtration device 101 according to the first embodiment will be described. Fig. 4 is an explanatory diagram showing a schematic configuration of a modified suction filtration device 101A. As shown in Fig. 4, the modified suction filtration device 101A differs from the suction filtration device 101 shown in Fig. 1 in that a sealed container 22 is installed between the container 1 and the pipeline L1.

[0054] A filtrate collection container 21 is provided inside the sealed container 22. The liquid w1 flowing out from the container 1 via the filter 6 is introduced into the sealed container 22 and poured into the filtrate collection container 21. When the liquid w1 poured into the filtrate collection container 21 overflows, the liquid w1 flows from the sealed container 22 into the pipeline L1 and is introduced into the trap bottle 2 via the solenoid valves SV1 and SV2, as in the first embodiment described above.

[0055] In the suction filtration device 101A according to the modified example, as in the first embodiment described above, the completion of filtration of the liquid w1 can be detected immediately, the solenoid valves SV1 and SV2 can be closed, and the suction pump P1 can be stopped. This prevents the solid matter filtered by the filter 6 from being exposed to airflow after filtration is complete, and prevents the solid matter from drying out. Furthermore, the filtrate obtained by filtering the liquid w1 through the filter 6 can be collected in the filtrate collection container 21.

[0056] [Description of the Second Embodiment] Next, a second embodiment of the present invention will be described. Fig. 5 is an explanatory diagram schematically showing the configuration of a suction filtration device 102 according to the second embodiment. As shown in Fig. 5, the suction filtration device 102 according to the second embodiment includes a container 1, a trap bottle 2, a suction pump P1, an airflow sensor 7, a control unit 5A, two solenoid valves SV1 and SV2, and pipelines L1 and L2.

[0057] The container 1, trap bottle 2, suction pump P1, two solenoid valves SV1 and SV2, and pipelines L1 and L2 have the same configuration as those in the first embodiment described above, so they are denoted by the same reference numerals and description thereof will be omitted.

[0058] The airflow sensor 7 is installed in the conduit L1 between the two solenoid valves SV1 and SV2. The airflow sensor 7 detects the flow speed of air flowing through the conduit L1. The airflow sensor 7 is equipped with, for example, a propeller and measures the rotation speed of the propeller. The airflow sensor 7 detects that air has flowed into the conduit L1 when the airflow speed exceeds a predetermined upper limit speed. The airflow sensor 7 outputs data on the measured rotation speed to the control unit 5A.

[0059] The control unit 5A controls the operation of the suction pump P1 and the opening and closing of the solenoid valves SV1 and SV2. The control unit 5A determines whether air has flowed into the conduit L1 based on the air flow velocity in the conduit L1 detected by the airflow sensor 7. That is, after the suction pump P1 has completely filtered the liquid w1 in the container 1, air then flows into the conduit L1. The inflow of air increases the air flow velocity in the conduit L1. The control unit 5A determines whether air has flowed into the conduit L1 based on the air flow velocity detected by the airflow sensor 7. That is, the control unit 5A functions as a determination unit that determines that the filtration of the liquid w1 in the container 1 has ended when the inflow of air into the conduit L1 is detected. The airflow sensor 7 also functions as a detection unit that detects the inflow of air into the conduit L1.

[0060] The control unit 5A determines that the filtration of the liquid w1 has finished when it detects that air has flowed into the pipeline L1. When the filtration of the liquid w1 stored in the container 1 has finished, the control unit 5A closes the solenoid valve SV2 and stops the suction pump P1. That is, after the filtration of the liquid w1 has finished, the control unit 5A closes the solenoid valve SV2 and stops the suction pump P1, thereby preventing solid matter (e.g., suspended matter) adhering to the filter 6 from being exposed to the airflow. The control unit 5A also notifies the user by displaying the completion of filtration on a display (not shown) or the like.

[0061] Next, the operation of the suction filtering device 102 according to the second embodiment will be described with reference to the flowcharts shown in Figures 6 and 7. As an initial setting, a liquid w1 (e.g., sewage) to be inspected is stored in a container 1. A filter 6 for filtering out solid matter is also installed at the drain outlet of the container 1.

[0062] In step S101 of FIG. 6, the control unit 5A starts the suction pump P1.

[0063] In step S102, the control unit 5A opens the solenoid valves SV1 and SV2, causing the suction pump P1 to start suctioning the liquid w1.

[0064] In step S103, the control unit 5A starts the suction pump P1 and then waits for a predetermined time (for example, a time until the airflow inside the pipe becomes stable).

[0065] In step S104, the control unit 5A starts acquiring the air flow velocity detected by the airflow sensor 7. In this process, the control unit 5A acquires the air flow velocity in the conduit L1 every time an arbitrary interval time (for example, 200 [msec]) elapses.

[0066] In step S105, the control unit 5A performs a filtering end determination process. Hereinafter, the detailed processing procedure of the filtering end determination process will be described with reference to the flowchart shown in FIG.

[0067] 7, the control unit 5A acquires the air flow velocity (AD converted value) detected by the airflow sensor 7 at each time the interval time elapses, and acquires the moving average value AV, the maximum moving average value Vmax, and the minimum moving average value Vmin from the flow velocity for a specified number of times (for example, 20 times). At this time, the maximum moving average value Vmax is saved as a peak hold value. That is, the maximum moving average value of the flow velocity detected after detection by the airflow sensor 7 begins is saved as Vmax.

[0068] In step S152, the control unit 5A resets the count value CT of the counter.

[0069] In step S153, the control unit 5A compares the moving average value AV(t) of the flow velocity calculated in the current calculation for a specified number of times (for example, 20 times) with the moving average value AV(t-1) calculated in the previous calculation, and determines whether or not "AV(t)>AV(t-1)". If "AV(t)>AV(t-1)" holds (S153; YES), the process proceeds to step S154; if not (S153; NO), the process returns to step S152.

[0070] In step S154, the control unit 5 increments the count value CT of the counter, that is, "CT=CT+1."

[0071] In step S155, the control unit 5 determines whether the count value CT has reached the threshold value CTth. If it has reached the threshold value CTth (S155; YES), the process proceeds to step S156; if not (S155; NO), the process returns to step S53.

[0072] In step S156, the control unit 5A calculates the difference DT between the maximum moving average value Vmax and the minimum moving average value Vmin of the flow velocity, that is, "DT=Vmax-Vmin."

[0073] In step S157, the control unit 5A determines whether the difference DT is equal to or greater than a predetermined threshold value DTth. If "DT≧DTth" (S157; YES), the process proceeds to step S158; if not (S157; NO), the process returns to step S156.

[0074] In step S158, the control unit 5A determines that the suction filtration of the liquid w1 has ended.

[0075] In step S106 of FIG. 6, the control unit 5A closes the solenoid valves SV1 and SV2.

[0076] In step S107, the control unit 5A stops the suction pump P1. In this way, when the filtration of the liquid w1 stored in the container 1 is completed and the liquid w1 in the container 1 is depleted, the control unit 5A closes the electromagnetic valve SV2 and stops the suction pump P1, thereby completing the filtration.

[0077] In this way, in the suction filtration device 102 according to the second embodiment, by driving the suction pump P1, solid matter in the liquid w1 can be filtered, and nucleic acids, which are genetic material, can be extracted from, for example, microorganisms and viruses associated with infectious diseases contained in the solid matter.

[0078] Furthermore, when the filtration of the liquid w1 stored in the container 1 is completed and the liquid w1 in the container 1 is depleted, air flows into the conduit L1, causing an increase in the air flow rate in the conduit L1. The control unit 5A detects the increase in flow rate and determines the end of filtration. Therefore, when the filtration of the liquid w1 is completed, this can be detected immediately, the solenoid valves SV1 and SV2 can be closed, and the suction pump P1 can be stopped. This prevents the solid matter filtered by the filter 6 from being exposed to the airflow after filtration is completed, and prevents the solid matter from drying out. Furthermore, the second embodiment may also be configured to include the sealed container 22 and filtrate collection container 21 shown in FIG. 4, as in the first embodiment described above. This makes it possible to collect the filtrate.

[0079] [Description of the Third Embodiment] Fig. 8 is an explanatory diagram schematically showing the configuration of a suction filtration device 103 according to the third embodiment. As shown in Fig. 8, the suction filtration device 103 according to the third embodiment includes a container 1, a trap bottle 2, a suction pump P1, a cylinder 11, a position sensor 12, a control unit 5B, a solenoid valve SV11, and pipelines L11, L12, and L13.

[0080] The container 1 stores a liquid w1, such as sewage, in the same manner as in the first embodiment described above. A filter 6 is provided at a drain outlet on the bottom of the container 1 to filter out solid matter contained in the liquid w1. The solid matter includes, for example, microorganisms and viruses related to infectious diseases. The filter 6 is made of, for example, glass fiber, and collects the solid matter contained in the liquid w1.

[0081] A lid 1A is provided on the upper opening of the container 1. By attaching the lid 1A to the container 1, the inside of the container 1 can be sealed, preventing the intrusion of outside air. The drain outlet of the container 1 is connected to a trap bottle 2 via a pipe L11. The trap bottle 2 is also connected to a suction port of a suction pump P1 via a pipe L12. An electromagnetic valve SV11 is installed on the path of the pipe L11. The pipes L11 and L12 directly or indirectly connect the drain outlet of the container 1 to the suction port of the suction pump P1.

[0082] One end of a conduit L13 is connected to the lid 1A of the container 1. The other end of the conduit L13 is connected to a tube 11A of the cylinder 11. A piston 11B of the cylinder 11 slides in response to the pressure inside the tube 11A. That is, the cylinder 11 has a tube 11A and a piston 11B, and the tube 11A is connected to the lid 1A of the container 1. The piston 11B slides in response to the air pressure inside the tube 11A. Specifically, when the pressure inside the tube 11A is high, the piston 11B slides in the expanding direction (downward in the figure), and when the pressure inside the tube 11A is low, the piston 11B slides in the contracting direction (upward in the figure).

[0083] Position sensor 12 detects the position of piston 11B. When the air pressure inside container 1 decreases and piston 11B slides in the contracting direction and reaches a predetermined position, position sensor 12 outputs a detection signal of the decrease in air pressure to control unit 5B. In other words, position sensor 12 functions as a measurement unit that measures the sliding position of piston 11B.

[0084] The suction port of the suction pump P1 is connected to the discharge port of the container 1 via a pipe L12, a trap bottle 2, and a pipe L11. By driving the suction pump P1, the liquid w1 stored in the container 1 can be sucked. By sucking the liquid w1 with the suction pump P1, solid matter can be filtered out by the filter 6 contained in the liquid w1. The filtered liquid w1 can be stored in the trap bottle 2.

[0085] The control unit 5B controls the operation of the suction pump P1 and the opening and closing of the solenoid valve SV11. The control unit 5B determines whether or not the filtration of the liquid w1 stored in the container 1 has been completed based on the detection signal of the drop in air pressure output from the position sensor 12. That is, when the liquid w1 is stored in the container 1, the pressure in the container 1 is high. When the filtration of the liquid w1 in the container 1 has been completed, the suction pump P1 sucks the air in the container 1, causing the pressure in the container 1 to drop, which in turn causes the pressure in the tube 11A to drop. As a result, the piston 11B slides in the contracting direction, and the position sensor 12 detects that it has reached a predetermined position. That is, the control unit 5B functions as a determination unit that determines that the filtration of the liquid w1 in the container 1 has been completed when the air pressure in the tube 11A drops and the sliding position of the piston 11B reaches a predetermined position.

[0086] Based on the detection signal of the drop in air pressure, the control unit 5B determines that filtration of the liquid w1 has been completed. When filtration of the liquid w1 stored in the container 1 has been completed, the control unit 5B stops the suction pump P1. That is, after filtration of the liquid w1 has been completed, the control unit 5B closes the solenoid valve SV2 and stops the suction pump P1, thereby preventing solid matter (e.g., suspended matter) adhering to the filter 6 from being exposed to the airflow. The control unit 5B also notifies the user by displaying the completion of filtration on a display (not shown) or the like.

[0087] Next, the operation of the suction filtering device 103 according to the third embodiment will be described with reference to the flowchart shown in Fig. 9. As an initial setting, a liquid w1 (e.g., sewage) to be inspected is stored in a container 1. A filter 6 for filtering out solid matter is also installed at the drain outlet of the container 1.

[0088] First, in step S201 of FIG. 9, the control unit 5B starts the suction pump P1.

[0089] In step S202, the control unit 5B opens the electromagnetic valve SV11, causing the suction pump P1 to start suctioning the liquid w1.

[0090] In step S203, the control unit 5B waits for 200 msec after starting the suction pump P1.

[0091] In step S204, the control unit 5B starts detecting the position of the piston 11B in the cylinder 11. Specifically, the control unit 5B starts detecting the position of the piston 11B using the position sensor 12 installed near the piston 11B. In this process, the control unit 5B acquires the position of the piston 11B from the position sensor 12 every 200 msec.

[0092] In step S205, the control unit 5B determines whether the position of the piston 11B has reached a predetermined position. If the position has reached the predetermined position (S205; YES), it is determined that the filtration of the liquid w1 stored in the container 1 has been completed.

[0093] In step S207, the control unit 5B closes the solenoid valve SV11.

[0094] In step S208, the control unit 5B stops the suction pump P1. In this way, when the filtration of the liquid w1 stored in the container 1 is completed and the liquid w1 in the container 1 is depleted, the control unit 5B closes the electromagnetic valve SV2 and stops the suction pump P1, thereby completing the filtration.

[0095] In this way, in the suction filtering device 103 according to the third embodiment, by driving the suction pump P1, solid matter in the liquid w1 can be filtered, and proteins such as RNA contained in the solid matter can be collected.

[0096] Furthermore, when filtration of the liquid w1 stored in the container 1 is completed and the liquid w1 in the container 1 is depleted, the pressure in the tube 11A of the cylinder 11 decreases, causing the piston 11B to slide to a predetermined position. Therefore, the end of filtration can be immediately detected, the solenoid valve SV11 can be closed, and the suction pump P1 can be stopped. This prevents the solid matter filtered by the filter 6 from being exposed to airflow after filtration is completed, thereby preventing the solid matter from drying out. Furthermore, the third embodiment may also be configured to include the sealed container 22 and filtrate collection container 21 shown in FIG. 4, as in the first embodiment described above. This allows the filtrate to be collected.

[0097] Although the embodiments of the present invention have been described above, the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. From this disclosure, various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art. [Explanation of symbols]

[0098] 1 container 1A Lid body 2 Trap Bottle 4 Pressure sensor (detection part) 5, 5A, 5B control section 6 Filters 7 Airflow sensor (detection part) 11 cylinders 11A tube 11B Piston 12 Position Sensor 101, 102, 103 Suction filtration device L1, L2, L11, L12, L13 pipes P1 Suction pump (pump) w1 liquid

Claims

1. a container for storing a liquid; a filter disposed at a drain outlet of the container for filtering out solid matter contained in the liquid; a pump for sucking the liquid; a conduit directly or indirectly connecting the drain port and the suction port of the pump; a detection unit that detects an inflow of air into the pipeline; a determination unit that determines that filtration of the liquid in the container has been completed when air inflow into the pipeline is detected; A suction filtration device comprising:

2. The detection unit a pressure sensor for measuring the pressure in the pipeline; The pressure sensor monitors pressure changes in the conduit, and when a predetermined pressure change is detected, detects that air has flowed into the conduit. The suction filtration device according to claim 1 .

3. The detection unit an airflow sensor for detecting an airflow velocity in the duct; The airflow sensor detects the inflow of air into the duct when the airflow velocity exceeds a predetermined upper limit velocity. The suction filtration device according to claim 1 .

4. A trap bottle for collecting the liquid that has passed through the filter is installed between the pipeline and the suction port of the pump. The suction filtration device according to any one of claims 1 to 3.

5. A valve for switching between passing and sealing the liquid is provided in each of the pipes on the upstream side and downstream side of the detection unit. The suction filtration device according to claim 1 .

6. a container having a sealed structure and configured to store a liquid; a filter disposed at a drain outlet of the container for filtering out solid matter contained in the liquid; a pump for sucking the liquid; a conduit directly or indirectly connecting the drain port and the suction port of the pump; a cylinder including a tube connected to a lid of the container and a piston that slides in response to air pressure in the tube; a measuring unit for measuring a slide position of the piston; a determination unit that determines that filtration of the liquid in the container has been completed when the air pressure in the tube decreases and the sliding position of the piston reaches a predetermined position; A suction filtration device comprising:

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