Clean air system

Abstract

We provide a clean air system that offers a method for determining filter clogging while maintaining both accuracy and cost-effectiveness. [Solution] A clean air device having a filter, comprising an airflow sensor for measuring the airflow after passing through the filter, and a differential pressure sensor for measuring the pressure difference before and after the filter, wherein a second life prediction line is created so as to match the rate of change of a second life prediction line, which is measured by a sensor different from the sensor used to create the first life prediction line, with the rate of change of a second life prediction line, which is measured by a sensor different from the one used to create the first life prediction line, to the rate of change of a first life prediction line relating to air velocity obtained from the initial value and the value during correction measurement of either the airflow sensor or the differential pressure sensor, and the clean air device manages the filter based on the first life prediction line or the second life prediction line.

Description

Technical Field

[0001] The present invention relates to a clean air device.

Background Art

[0002] Clean air devices have various forms such as safety cabinets, FFUs (Fan Filter Units), air shower devices, etc., and are all devices having an air purification function.

[0003] As an example of a safety cabinet, there is Patent Document 1. Patent Document 1 discloses a configuration in which clean air is exhausted from a duct 20 to the outside through an exhaust filter 18.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As time passes during use, the filter gradually becomes clogged. Therefore, it is necessary to detect a decrease in the purification performance of the filter and determine at which stage to replace it.

[0006] Patent Document 1 does not disclose any content regarding the determination of filter replacement.

[0007] One method for determining filter replacement is to provide a differential pressure sensor that measures the differential pressure between the input side and the output side of the filter. This is a method of determining that the clogging of the filter has progressed when the differential pressure increases. There is also a method of providing a wind speed sensor on the output side of the filter. This is a method of determining that the clogging has progressed when the wind speed decreases.

[0008] However, methods using differential pressure sensors or wind speed sensors alone are prone to large errors due to sensor variations, etc. In terms of accuracy, differential pressure sensors offer superior performance. However, they do not directly indicate airflow, so they cannot be directly applied as the final control indicator. On the other hand, wind speed sensors can be applied as the final control indicator, but they suffer from lower accuracy. Therefore, to ensure filter performance, early filter replacement is necessary, which leads to increased filter replacement frequency and filter costs.

[0009] Therefore, achieving both accuracy and cost-effectiveness has traditionally been difficult.

[0010] Therefore, the present invention aims to provide a clean air device that has a method for determining filter clogging while achieving both accuracy and cost-effectiveness. [Means for solving the problem]

[0011] One example of how to solve the above problem is as follows:

[0012] A clean air device having a filter, comprising an airflow sensor for measuring the airflow after passing through the filter, and a differential pressure sensor for measuring the pressure difference before and after the filter, wherein a second life prediction line is created so as to match the rate of change of a second life prediction line, which is measured by a sensor different from the sensor used to create the first life prediction line, with the rate of change of a second life prediction line, which is measured by a sensor different from the one used to create the first life prediction line, to the rate of change of a first life prediction line relating to air velocity obtained from the initial value and the value during correction measurement of either the airflow sensor or the differential pressure sensor, and the clean air device manages the filter based on the first life prediction line or the second life prediction line. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a clean air device that has a method for determining filter clogging while achieving both accuracy and cost-effectiveness.

[0014] The further configuration and effects of the present invention will become clear throughout the following full text of the specification.

Brief Description of the Drawings

[0015] [Figure 1] This is an example of the configuration diagram of the present invention. [Figure 2] This is a front view of the safety cabinet. [Figure 3] This is a side view of the safety cabinet. [Figure 4] This is a schematic explanatory diagram of the B-B cross-section of FIG. 3. [Figure 5] This is a schematic explanatory diagram of the A-A cross-section of FIG. 2. [Figure 6] This is an example of the characteristic diagram of the wind speed sensor. [Figure 7] This is an example of the characteristic diagram of the differential pressure sensor. [Figure 8A] This is the transition of the differential pressure sensor over time and its output. [Figure 8B] This is the transition of the wind speed sensor over time and its output. [Figure 8C] This is the transition of the differential pressure sensor and the wind speed sensor over time and their outputs. [Figure 8D] This is the transition of the differential pressure sensor and the wind speed sensor over the corrected time and their outputs. [Figure 8E] This is an explanatory diagram of the warning value W. [Figure 8F] This is an explanatory diagram of the warning value E. [Figure 8G] This is an explanatory diagram of the warning values W and E. [Figure 8H] This is an explanatory diagram of the abnormal value. [Figure 9A] This is an explanatory diagram of an example of the processing flow. [Figure 9B] This is an explanatory diagram of an example of the processing flow. [Figure 10A] This is an explanatory diagram of an example of the processing flow. [Figure 10B] This is an explanatory diagram of two examples of the processing flow. [Figure 11A] This is an explanatory diagram of an example of the sensor data processing. [Figure 11B]This is an explanatory diagram illustrating an example of sensor data processing. [Figure 12A] This is an example of a screen display. [Figure 12B] This is an example of a screen display. [Figure 12C] This is an example of a screen display. [Figure 12D] This is an example of a screen display. [Figure 12E] This is an example of a screen display. [Figure 12F] This is an example of a screen display. [Figure 12G] This is an example of a screen display. [Figure 12H] This is an example of a screen display. [Figure 13] This is an explanatory diagram illustrating an example of sensor data processing. [Modes for carrying out the invention]

[0016] The embodiments of the present invention will be described below, with reference to drawings as necessary. [Examples]

[0017] Figure 1 is an example of a configuration diagram of the present invention. 1 is a filter. The explanation will be given in the case where air flows from bottom to top in the figure, as shown in airflow 114, passing through the filter.

[0018] The differential pressure sensor 21 measures the differential pressure, which is the difference in pressure between the primary pressure port 22 and the secondary pressure port 23. As the filter 1 becomes clogged, the differential pressure measured by the differential pressure sensor 21, or the output value from the differential pressure sensor 21, increases.

[0019] An air velocity sensor 24 is used in addition to the differential pressure sensor 21. In this invention, both the data from the differential pressure sensor 21 and the data from the air velocity sensor 24 are utilized to determine filter clogging while maintaining both accuracy and cost-effectiveness.

[0020] Therefore, the main targets of application are various clean air devices having the configuration shown in Figure 1, such as safety cabinets, air shower devices, FFUs for devices, and ceiling-mounted FFUs.

[0021] A specific method for utilizing both the data from the differential pressure sensor 21 and the data from the wind speed sensor 24 will be described later using Figures 6 to 8.

[0022] Next, as an example of a clean air system, we will describe an example of the structure of a safety cabinet.

[0023] Figure 2 is a front view of the safety cabinet of the present invention. 100 is the safety cabinet. 10 is the top housing, 11 is the side housing, 12 is the front housing, 13 is the bottom housing, and 20 is the legs.

[0024] 123 is a decorative cover. It houses the lighting and control electrical components, and is equipped with the differential pressure sensor 21, programmable display 26, and PLC (programmable logic controller) 27, which are features of the present invention.

[0025] A transparent glass front shutter 103 moves up and down on the back side of the decorative cover.

[0026] 104 is a working opening defined as the space between the front housing 12 and the lower surface of the front shutter 103.

[0027] Figure 3 is a side view of the safety cabinet of the present invention. 100 is the safety cabinet. 11 is the side housing, 13 is the lower housing, 20 is the legs, and 123 is the decorative cover.

[0028] Figure 4 is a schematic diagram illustrating the BB section of Figure 3, and Figure 5 is a schematic diagram illustrating the AA section of Figure 2. For explanatory purposes, some details have been omitted, and members that are not precisely located in the same position as the actual section are also shown in these diagrams.

[0029] The safety cabinet 100 has a workspace 102 inside, with a front shutter 103 at the front. The bottom of the workspace 102 is a workbench 101, and a front slit 104a is located on the front shutter 103 side of the workbench 101. A work opening 104 is formed below the front shutter 103. When the safety cabinet's air supply fan 106 is operated, it pressurizes the upper chamber 109. A discharge HEPA filter 111 is connected to the upper chamber 109, filtering dust inside the upper chamber 109, and the purified air is discharged, rectified by a discharge rectifier plate 107, and then supplied to the workspace 102 as a discharge airflow 113.

[0030] An exhaust HEPA filter 110 is also connected to the upper chamber 109. Air from the supply fan 106 is filtered by the exhaust HEPA filter 110. It then passes through the exhaust port 108 of the safety cabinet and is exhausted from the safety cabinet 100 as airflow 114. An equal amount of air enters the safety cabinet 100 to replace the air being exhausted. This air is the incoming airflow 112 drawn in from the work opening 104 below the front shutter 103. The incoming airflow 112, along with a portion of the outflow airflow 113 from the work space 102, is drawn into the front slit 104a. This air passes through the exhaust circulation path 117 below the workbench 101 and is drawn in along with a portion of the outflow airflow 113 from the rear slit 105a formed on the opposite side of the front shutter 103 of the work space 102, passes through the rear path 105, and is drawn into the supply fan 106 of the safety cabinet. As a result, the incoming airflow 112 from the work opening 104 is completely drawn into the front slit 104a and discharged, so it does not flow into the work space 102, and acts as an air barrier for the incoming airflow 112 from the work opening 104. 105a is the rear slit, and 115 is a lighting fixture.

[0031] Within the workspace 102, one example of the use and purpose of the safety cabinet is handling infectious materials such as pathogens and aerosols. In such cases, infectious materials including pathogens and aerosols will also be present in the rear passage 105 and the upper chamber 109. When supplying air to the workspace 102 and when exhausting air from the safety cabinet 100, these infectious materials and aerosols are removed by the outlet HEPA filter 111 and the exhaust HEPA filter 110.

[0032] The worker sits in front of the safety cabinet 100, inserts their arm into the workspace 102 through the work opening 104, and performs their work while looking into the workspace 102 through the front shutter 103. At this time, brightness is ensured by illuminating the workspace 102 with the lighting fixture 115. In such a safety cabinet, the worker uses the front shutter at an opening specified by the manufacturer, for example, a 200 mm opening.

[0033] When work is completed, the workbench 101 is wiped down with disinfectant ethanol or the like, the front shutter 103 is closed, and the germicidal lamp 116 is turned on for a certain period of time to disinfect the surface of the workbench 101.

[0034] As described above, in the safety cabinet 100, the air barrier, which is the inflow airflow 112, is important for ensuring the safety of workers. This prevents infectious materials such as pathogens and aerosols handled in the workspace 102 from leaking out of the safety cabinet 100 and infecting people. In order to maintain the air barrier, it is important that the inflow airflow 112 and outflow airflow 113 of the safety cabinet 100 continue to maintain within the specified air velocity range.

[0035] Therefore, the present invention improves the accuracy of predicting the lifespan of the HEPA filter by monitoring the decrease in airflow velocity due to clogging of the HEPA filter, which varies depending on the usage environment and conditions, through multiple state monitoring.

[0036] Here, we will explain the roles of the wind speed sensor 24 and pressure ports 22 and 23 shown in Figure 4.

[0037] As mentioned above, an amount of air equal to the airflow 114 flows into the safety cabinet 100 as the incoming airflow 112, acting as an air barrier. Therefore, to ensure an air barrier, it is sufficient to maintain the airflow 114 within a specified range. Accordingly, the wind speed sensor 24 is placed at a position where it detects the clean air after the air pushed out by the supply fan 106 has passed through the exhaust HEPA filter 110, thereby detecting the exhaust wind speed. This is because it is better to place the wind speed sensor in a position where clean air passes, in order to prevent false detections due to dirt on the wind speed detection part of the wind speed sensor. The wind speed sensor used has an electrical output signal function, and there are types that change the output voltage according to changes in wind speed, for example.

[0038] To verify the wind speed performance of the safety cabinet 100, an anemometer specified in JIS_K_3800 Class 2 cabinets for biohazard countermeasures is used. This is a low-speed anemometer specified in JIS_T_8202, with an indication accuracy of ±0.015 m / s for readings of 0.5 m / s or less, and ±3% for readings exceeding 0.5 m / s. This is used for factory inspections and periodic maintenance of safety cabinets. However, anemometers with this level of accuracy are expensive, making them unsuitable for continuous monitoring of the safety cabinet's wind speed. Therefore, for the purpose of continuously monitoring the wind speed in a safety cabinet, it is possible to reduce costs while ensuring the necessary accuracy by using a sensor that does not meet the above absolute accuracy but has a repeatability (repeatability characteristic) accuracy that is higher than the above accuracy.

[0039] Furthermore, conditions that cause a decrease in airflow velocity include not only clogging of the HEPA filter, but also malfunctions of fan control components such as the supply fan 106 and inverter, foreign matter contamination of the exhaust HEPA filter and supply fan 106, obstruction of airflow in the workspace 102 by installing large experimental equipment on the workbench 101, and blockage of the exhaust port 108. Therefore, a differential pressure sensor 21 is installed to measure the differential pressure between the upstream and downstream of the exhaust HEPA filter 110. Primary pressure ports 22 and secondary pressure ports 23 are installed and connected to the high-pressure or low-pressure side of the piping connection port of the differential pressure sensor 21 with vinyl tubing or the like to monitor the differential pressure between the upstream and downstream of the exhaust HEPA filter 110. This allows the exhaust HEPA filter 110 to be determined to be clogged only when the airflow velocity passing through the exhaust HEPA filter 110 decreases and the differential pressure between the upstream and downstream of the exhaust HEPA filter 110 increases.

[0040] Figure 6 shows an example of a characteristic diagram of the wind speed sensor 24. The wind speed sensor 24 has the characteristic that its output voltage changes with the wind speed. The horizontal axis represents the relative value of the wind speed. From the initial X' to the final Y', as the wind speed decreases due to filter clogging during use, the output voltage from the wind speed sensor 24 decreases.

[0041] Figure 7 shows an example of a characteristic diagram of the differential pressure sensor 21. The differential pressure sensor 21 has the characteristic that the output current changes with the change in differential pressure. The horizontal axis represents the relative value of the differential pressure. The differential pressure sensor 21 detects the differential pressure between the primary side, which is the upstream side of the exhaust HEPA filter 110, and the secondary side, which is the downstream side. Therefore, as the differential pressure increases due to filter clogging during use, from the initial X to the final Y, the output current from the differential pressure sensor 21 increases.

[0042] Furthermore, wind speed sensors and differential pressure sensors with these characteristics are widely available on the market.

[0043] As the clean air system operates for an extended period, dust is collected by the exhaust HEPA filter 110. As a result, the air resistance of the exhaust HEPA filter 110 increases, causing the differential pressure to rise. This simultaneously means that the airflow velocity decreases.

[0044] The following describes a filter clogging detection method that balances accuracy and cost by correcting the correlation between the output current of the differential pressure sensor and the output voltage of the wind speed sensor, using Figures 8A to 8D. The following explanation uses the example of creating a wind speed sensor life prediction line using a life prediction line where the differential pressure sensor value is considered positive. Figure 8A shows the time course of the differential pressure sensor output. The horizontal axis represents time. As usage time progresses, the filter becomes clogged and the differential pressure increases. As shown in the figure, this is detected as an increase in the output current of the differential pressure sensor on the vertical axis.

[0045] The initial state is at time A, and the output current of the differential pressure sensor is X. The end of the filter's lifespan is at time D, and the output current of the differential pressure sensor is Y. Y is a predicted calculated value. Then, at the time of the first inspection or correction inspection, it is time B, and the output current of the differential pressure sensor is Z. Figure 8A can also be called the differential pressure sensor life prediction line, or the first life prediction line.

[0046] Figure 8B shows the time course of the wind speed sensor output. The horizontal axis represents time. As usage time progresses, the filter becomes clogged and the wind speed decreases. As shown in the figure, this is detected as a decrease in the output voltage of the wind speed sensor, which is on the vertical axis.

[0047] The initial state is at time D', and the output voltage of the wind speed sensor is X'. The end of the filter's lifespan is at time A', and the output voltage of the wind speed sensor is Y'. Y' is a predicted calculated value.

[0048] Figure 8B can also be referred to as the life prediction line for the wind speed sensor, or the second life prediction line.

[0049] Figure 8C is a diagram that combines Figures 8A and 8B into a single figure. The graphs for the output current of the differential pressure sensor and the output voltage of the wind speed sensor have different slopes and magnitudes, and at this stage, they remain separate pieces of information.

[0050] Therefore, the inventors considered providing a clean air device with a filter clogging detection method that balances accuracy and cost by correcting the correlation between the output current of the differential pressure sensor and the output voltage of the wind speed sensor.

[0051] Figure 8D is a graph obtained by correcting Figure 8C so that there is a correlation between the output current of the differential pressure sensor and the output voltage of the wind speed sensor.

[0052] One example of how to perform the correction is to match the slope of the output voltage of the wind speed sensor to the slope of the output current of the differential pressure sensor, as shown in Figure 8C. Then, A and A' are made to match, and D and D' are made to match.

[0053] Figure 8D can also be referred to as the corrected lifetime prediction line.

[0054] As a result, as shown in Figure 8D, A and A' coincide, and D and D' coincide. Also, the length between X and Z and the length between X' and Z' coincide. This makes it possible to represent the time course of the output current of the differential pressure sensor and the time course of the output voltage of the wind speed sensor on the same linear axis. Note that Z' is the wind speed sensor output voltage when the same predetermined time has elapsed from D as the time elapsed from A (time between A and B) (time between D and D).

[0055] As a result, for example, since using a wind speed sensor with high accuracy would be expensive, even if an inexpensive one is used, it is possible to create a life prediction line for the wind speed sensor using a life prediction line that takes the average value of the differential pressure sensor as positive, as explained in the above embodiment, thereby providing a clean air device with a filter clogging detection method that balances accuracy and cost.

[0056] Additionally, as a supplementary measure to further improve the accuracy of the wind speed sensor, when measuring X', the wind speed may be measured using an expensive, high-precision anemometer installed externally only at that time. Based on the results, a correction factor may be applied to the output voltage of the wind speed sensor, such as by multiplying it by a correction factor or by adding it. This is because further improvements in accuracy can be expected.

[0057] In Figure 8D, the thick line relating to the differential pressure sensor output current connects the initial value of the differential pressure to the time of the first inspection or correction inspection. The thick line relating to the wind speed sensor output voltage connects the initial value of the wind speed to the time of the correction inspection. The triangle in the figure represents the wind speed sensor output voltage V' when time has elapsed from the initial value D to an arbitrary measurement time N'. By performing the correction, it becomes possible to accurately determine changes in wind speed by applying this value of V' to the wind speed sensor output voltage and wind speed graph in Figure 6.

[0058] Fundamentally, if an ultra-expensive and ultra-high-precision wind speed sensor were used from the outset, such correction processing would be unnecessary. However, in typical industrial applications and other mass-produced goods, there are limits to the component costs that can be allocated, making it difficult to adopt high-performance components regardless of cost. Therefore, the issue of the precision of the components themselves, and even variations between components, is unavoidable. This technology addresses this problem by using a correction method to achieve substantial improvements in precision and suppress the effects of variations, resulting in a significant performance improvement effect on mass-produced products.

[0059] Figure 8E shows an example where the first warning value W has been introduced. If the output voltage V' of the wind speed sensor (indicated by the triangle in the figure) exceeds the first warning value W, it can be determined that the degree of filter clogging is still minor. For example, this makes it possible to omit precise on-site wind speed measurements by workers during the next periodic inspection. This allows for labor savings in periodic inspection work and enables remote inspections.

[0060] Furthermore, if the output voltage V' of the wind speed sensor, represented by the triangle in the diagram, falls below the first warning value W, it is determined that the filter is becoming clogged to some extent. By outputting advance warning information, the equipment user can make prior arrangements for budgeting for ordering replacement filter parts.

[0061] Figure 8F shows an example where a component replacement warning value E has been introduced. This could also be called a second warning value. If the output voltage V' of the wind speed sensor, represented by the triangle in the figure, falls below the component replacement warning value E, it is determined that the filter is becoming clogged and a filter replacement is desirable, or will soon be desirable. An alarm is then issued, prompting the user to arrange for or order a replacement filter.

[0062] Figure 8G combines Figures 8E and 8F to show the relationship between W and E. It indicates that E is set lower than W, and that on the time axis, it is set to the left, representing a stage where the filter has been used for a longer period of time.

[0063] Furthermore, it is desirable that W and E also be corrected at the same time as the corrections made from Figure 8C to Figure 8D. In Figures 8E to 8F, an example is shown in which a first warning value W and a component replacement warning value E are set on the life prediction line of the wind speed sensor, and advance warnings and alarms are output. However, the first warning value W and a component replacement warning value E may also be set on the life prediction line of the wind pressure sensor, and advance warnings and alarms may be output. If the judgment is made using a sensor that only has the accuracy of reproducibility (repeatability characteristics), the absolute value is unreliable but the relative value is reliable. On the other hand, if the judgment is made using a sensor that has the necessary absolute accuracy, there will be variations in the components, but the absolute value is reliable. Therefore, regardless of which life prediction line is used, both the reproducibility and the absolute value are reliable, and can be used for advance warnings and alarms.

[0064] Figure 8H shows an example of a situation during an irregular event. 25 represents abnormal data, which is temporarily detected over time and then disappears.

[0065] Such temporary anomaly data is judged to reflect temporary equipment usage or installation conditions and is not indicative of a malfunction in the filter itself. This makes it possible to avoid unnecessary filter replacements.

[0066] Alternatively, if such abnormal data is detected in either the output voltage of the wind speed sensor or the output current of the differential pressure sensor, or if there is a significant difference in the degree of abnormality between the two, abnormal data will be detected, and before it disappears, it can be determined that the equipment is in an inappropriate state of use or installation, and the user can be asked to check and correct the usage and installation conditions. Specifically, in the case of a safety cabinet, this would be the case if too many items are placed in the work room or if an obstruction is placed in the exhaust path. In such cases, by asking the user to check and correct the usage and installation conditions, the user can understand the situation and take corrective action. This makes it possible to operate the clean air system in an appropriate state.

[0067] Furthermore, each figure in Figure 8 can also be referred to as an example of a filter life prediction characteristic diagram. In addition, although the above explanation described the case where a life prediction line for the wind speed sensor is created using a life prediction line where the value of the differential pressure sensor is positive, a life prediction line for the wind pressure sensor may also be created using a life prediction line where the value of the wind speed sensor is positive.

[0068] As shown in Figure 8D, by representing the wind speed sensor output voltage and differential pressure sensor output current with a single approximate straight line, or by applying a similar correction, it becomes possible to display a comparison of wind speed and pressure, and to monitor each other's output data. Therefore, it is also possible to implement a function to detect failures or abnormalities in either sensor.

[0069] As an example, for displays such as Figure 8D, it is desirable to configure a program using a device with display and operation functions, such as a programmable display unit 26, and a PLC (programmable logic controller) 27. The program is then configured by connecting the electrical output signal cables of the differential pressure sensor 21 and the wind speed sensor 24 to the input terminals of the PLC 27, extracting the output data, performing calculations, and displaying the calculation results, such as Figure 8D, on the programmable display unit 26.

[0070] The programmable display unit 26 should, for example, be placed on the decorative cover 123 on the front of the safety cabinet 100, in a position where it is always visible to the worker.

[0071] Figure 9A shows an example of the operation flow. Step S1 is the installation inspection. X in Figure 8A and X' in Figure 8B are measured. Step S2 is the correction measurement after time has elapsed. Z in Figure 8A is measured. Note that the timing of the correction measurement is to be performed at the time of the initial inspection.

[0072] The lifespan of filters, including the exhaust HEPA filter 110, depends on the amount of dust in the installation environment, temperature and humidity, and usage time. However, by performing correction measurements during the initial inspection, or at appropriate intervals such as one year, and creating the profile after a certain period of actual use, a profile for the actual usage environment can be created. This improves the accuracy of the time when the wind speed reaches the lower limit of the specification value (end Y'), enabling more accurate lifespan prediction and management.

[0073] Furthermore, X' may be the value obtained from the wind speed sensor built into the device. However, a high-precision wind speed measuring device may be brought in from an external source, and correction measurements may be performed on the built-in wind speed sensor to derive and apply correction formulas, correction coefficients, or additive values ​​that result in higher accuracy.

[0074] When bringing in a high-precision anemometer, it is also acceptable to measure the wind speed using an anemometer specified in JIS_K_3800 Class 2 cabinets for biohazard countermeasures, plot the pressure value, and then measure the wind speed and plot the pressure value in the same manner during the periodic inspection one year later.

[0075] In step S3, the filter life is predicted based on the results of the correction measurement. Here, X', D', Y', and A' in Figure 8B are derived. It is not ruled out to predict only one of them and use a predetermined value for the other.

[0076] In step S4, the slopes of the wind speed sensor output voltage and the differential pressure sensor output current are adjusted to match, and the endpoint of one becomes the starting point of the other. This completes the filter lifetime prediction characteristic diagram shown in Figure 8D.

[0077] Then, using the filter's life prediction characteristic diagram, or equivalent data, the filter's status is managed in step S5. Note that even if the graphs are not combined as shown in Figure 8D, if they can be superimposed to look like Figure 8D, the wind speed sensor output voltage and the differential pressure sensor output current may be treated, processed, and judged separately.

[0078] Figure 9B is a flowchart showing an example of a decision criterion, replacing step S5 in Figure 9A.

[0079] In step S6, if the wind speed data has not decreased to the first warning value W, the filter clogging progression is considered minor, and wind speed measurement can be excluded from the next scheduled inspection, for example. In this case, the time required for scheduled inspections is reduced and efficiency is improved. Remote inspections also become possible.

[0080] In step S7, if the wind speed data drops to the second warning value E, it is assumed that the filter is becoming clogged, and an alarm is triggered, for example, prompting the arrangement of a replacement filter or ordering of long-lead-time parts. In this way, parts can be procured in advance. Then, in step S8, by replacing the parts during the next scheduled inspection, the downtime of the clean air system can be minimized.

[0081] If, for example, parts are not ordered in advance as in step S7, and the filter's lifespan is only confirmed during periodic inspections such as wind speed measurements, then parts must be ordered from that point onward, and replacement must be carried out after the parts are obtained. Depending on the type and condition of the filter, this may take several months. In the worst case, the clean air system may be forced to shut down for an extended period. By managing the flow to allow for advance parts ordering, as shown in Figure 9B, particularly in step S7, it is possible to reliably avoid prolonged shutdowns of the clean air system and minimize downtime.

[0082] Furthermore, by performing corrective measurements during the initial inspection, or at appropriate intervals such as one year, after a certain period of actual use has elapsed, a profile for the actual operating environment is created. This allows for the exclusion of wind speed measurements during periodic inspections if the time until the end date Y' exceeds one year. In addition, when the wind speed drops to a component replacement warning value E, which is set considering the component delivery time, an alarm buzzer or a display on the programmable indicator can be activated to prompt the ordering of components. As a result, component replacements can be carried out as planned during periodic inspections, wind speed measurements can be taken with the minimum necessary number of times, the downtime of the safety cabinet 100 can be reduced, and productivity can be improved.

[0083] Furthermore, by using the aforementioned data to compare data obtained under different environments and usage conditions, it can be useful for improving work processes and analyzing the causes of component degradation.

[0084] Figure 10A is an example of an operation flow corresponding to Figure 9B. It can also be described as a flow explained using different terminology.

[0085] Step S11 is the installation inspection. X' in Figure 8B is measured. Step S12 is the first periodic inspection. Z' in Figure 8B is measured.

[0086] In step S13, the filter life is predicted based on the operating conditions up to the first periodic inspection. This creates a profile for the actual operating environment.

[0087] In step S14, the slopes are matched and corrected so that the endpoint of one becomes the starting point of the other.

[0088] Steps S16 to S18 are the same as steps S6 to S8, respectively.

[0089] Figure 10B differs from Figure 10A in that step S15 is distinctive. It is more desirable that step S15 be performed continuously between steps S14 and S17 in the flow chart of Figure 10B.

[0090] Step S15 is a step in which a warning alarm is issued if one of the predicted values ​​deviates by a certain amount or more. This corresponds to the detection of abnormal data 25 in Figure 8H. Specifically, such cases are expected when too many items are placed in the work room or when an obstruction is placed in the exhaust path. In such cases, by suggesting that the user check the usage and installation conditions and take corrective action, the user can understand the situation and take corrective action. This makes it possible to operate the clean air system in an appropriate state. [Examples]

[0091] This embodiment is applied in combination with Example 1.

[0092] Figure 11A shows an example of sensor data processing. Data from the differential pressure sensor 21 and the wind speed sensor 24 are input to the PLC 27. The processing results and judgment results from the PLC 27 are displayed on the programmable display 26.

[0093] Figure 11A shows an example in which the clean air system itself is equipped with a PLC 27 and a programmable display 26.

[0094] However, if the room in which the safety cabinet 100 or clean air system is installed is to be treated as a cleanroom for cleanliness management, a control panel may be installed in a separate location, with a computing device inside to record the temperature, humidity, cleanliness, and operating status of the equipment used in the cleanroom. In this case, the electrical output signals of the wind speed sensor and differential pressure sensor may be connected to the computing device, and the recorder or calculations may be performed and the calculation results displayed. In this case, the safety cabinet 100 or clean air system does not require a programmable display or PLC, and can be centrally managed by the computing device. Alternatively, the safety cabinet 100 or clean air system may retain one or both of the programmable display and / or PLC, while the computing device performs the decision-making and processing.

[0095] Figure 11B shows an example where the computing unit 301 is located via a communication line 300 or electrical wiring. Data from the differential pressure sensor 21 and the wind speed sensor 24 are transmitted to the computing unit 301 as collected data 310, either via the PLC 27 or directly. The computing unit 301 can be located in a control panel, in a centralized control room, or as part of a remote management server or management cloud system, among other examples.

[0096] The arithmetic unit 301 performs some or all of the processing shown in Figures 8, 9, and 10. The results of the calculations are transmitted to the programmable display 26 as processed data 311 and displayed. Of course, the results may also be displayed on display means such as a control panel, a central control room, or a monitor provided in connection with a remote management server or management cloud system. [Examples]

[0097] This embodiment is applied in combination with at least one of Example 1 and Example 2.

[0098] This embodiment describes an example of display on the programmable display unit 26. This also includes display on display means such as a control panel, a central control room, or a monitor provided in connection with a remote management server or management cloud system.

[0099] Figure 12A shows an example of a screen display. It indicates that the filter's lifespan is nearing its end. For example, it might be displayed when the wind speed falls below W in Figure 8.

[0100] Figure 12B shows an example of a screen display. It indicates that the filter's lifespan is nearing its end and requests that replacement parts be ordered. For example, this display may appear when the wind speed reaches point E in Figure 8.

[0101] Figure 12C shows an example of a screen display. It indicates that the filter has reached the end of its lifespan. It indicates that the required performance cannot be achieved with continued use and more directly requests replacement of parts or the filter. For example, this is an example of a display when the wind speed falls below Y' in Figure 8.

[0102] Figure 12D shows an example of a screen display. This is an example of a screen configuration that includes a filter life management screen. Area 200 indicates normal, area 201 indicates caution, and area 202 indicates alarm, with one of these areas lighting up to allow the user to intuitively understand the filter status. Area 203 is a replacement parts order button. When the programmable display unit 26 is configured as a touch panel, the screen allows the user to order a replacement filter with a single click by touching area 203 or clicking with a mouse on the monitor. Since the model number and information of the filters used in the clean air system are pre-registered in the clean air system and the computing unit, the appropriate parts will be delivered even if the system is configured to allow ordering with a single click. For example, when the display in Figure 12B is shown, the user can operate the screen to display the life management screen in Figure 12D and click area 203 to order replacement parts without delay.

[0103] Figure 12E is an example of a screen display. It is a screen displaying wind speed data. In Figure 12E, the screen corresponding to Figure 6 is displayed as an example, but other screens such as those corresponding to Figures 8C to 8G may also be displayed.

[0104] Figure 12F is an example of a screen display. It is a screen displaying differential pressure data. In Figure 12F, the screen corresponding to Figure 7 is displayed as an example, but other screens such as those corresponding to Figures 8C to 8G may also be displayed.

[0105] Figure 12G is an example of a screen display. It is characterized by having a button for changing the use of area 210.

[0106] When multiple clean air devices, such as safety cabinets, are located in the same work area, each safety cabinet may not be performing the same task. Some safety cabinets may be used for tasks that are less frequently used or do not require a high level of cleanliness, such as pre-preparation or reagent mixing. In such cases, assigning equipment with clogged filters to these less frequently used or less cleanliness-requiring tasks can extend the time until the filters need replacing. This helps to reduce downtime when multiple clean air devices are present.

[0107] Furthermore, it is desirable to also arrange for replacement parts at that time. For this reason, the replacement parts order button in area 203 is also displayed in Figure 12G.

[0108] Furthermore, when the button in area 210 is pressed, it is desirable to display a message indicating that the use of the device is limited.

[0109] Figure 12H shows an example of a screen display. If the operating status of the device is higher than expected, or if the clogging of the filter is progressing higher than expected, a message recommending the addition of more units will be displayed in area 220, or a message recommending replacement with a high-performance product will be displayed in area 221. Note that the message display area may be in a different location. If excessive operation exceeding the expected conditions continues for a long period, it may result in increased waiting times for work and cleaning, which could lead to inefficiencies in the production process related to the use of the clean air device and a decrease in the actual operating rate. In such cases, by displaying a message recommending the addition of more units in area 220, or a message recommending replacement with a high-performance product in area 221, the user can use this as an opportunity to build a more efficient production system. [Examples]

[0110] This embodiment is an example of how it can be applied in combination with at least one of Examples 1 to 3.

[0111] Figure 13 shows that the data 310 collected from multiple safety cabinets 100 are aggregated in the computing unit 301. Note that the safety cabinets 100 include various clean air devices such as safety cabinets, air shower devices, FFUs for devices, and ceiling-mounted FFUs.

[0112] Based on the data collected by the computing unit 301, suppliers can place bulk orders, arrange bulk orders, or produce bulk quantities of filters. Large-scale users can also place bulk orders or arrange bulk orders. This makes it possible to avoid filter stockouts. Furthermore, in some cases, increasing the order quantity can reduce the unit price of filters.

[0113] Furthermore, by managing the next inspection date and the corresponding filter replacement date based on the collected data, it is possible to eliminate the need to replenish replacement filters excessively and optimize inventory levels. [Examples]

[0114] This embodiment is an example of applying any of Examples 1 to 4 to a ceiling-mounted FFU. Of course, the aforementioned effects can be achieved by applying the technical concepts of Examples 1 to 4.

[0115] Furthermore, ceiling-mounted FFUs have a unique characteristic that sets them apart from other clean air systems: the presence of multiple FFUs of the same specifications within the same space. For example, in a large cleanroom such as those found in semiconductor factories, dozens or more ceiling-mounted FFUs may be installed across the entire ceiling of a single room.

[0116] In such cases, the clogging of the filters in each ceiling-mounted FFU will progress almost simultaneously.

[0117] Therefore, when a large number of ceiling-mounted FFUs are installed, by equipping only some of them with at least one of the functions from Examples 1 to 3, and omitting the functions from the majority of the others, it is possible to reduce the overall cost while still providing filter life management functionality throughout the entire system.

[0118] One example is to equip only one unit in the center of the room with the function, while leaving the others without it. Alternatively, based on the concept of fail-safe, one could equip only a few units with the function, leaving the majority of the others without it.

[0119] In this embodiment, in addition to the effects of any of Examples 1 to 4, a reduction in equipment cost is achieved in the ceiling-mounted FFU without affecting performance.

[0120] As long as the ideas and concepts disclosed in the above descriptions are used, any modifications or similar examples thereof are also included within the scope of the present invention.

[0121] Furthermore, in the example of the safety cabinet, this includes not only the case where the differential pressure sensor 21 and the wind speed sensor 24 are used for managing the exhaust HEPA filter 110, but also the case where additional differential pressure sensors 21 and wind speed sensors 24 are provided for managing the discharge HEPA filter 111. In that case, the lifespans of the exhaust HEPA filter 110 and the discharge HEPA filter 111 can be managed separately.

[0122] Furthermore, an example of the present invention described using the above embodiments can also be expressed as follows.

[0123] <Part 1> In a clean air system having a filter, An airflow sensor that measures the airflow after passing through the filter, The filter has a differential pressure sensor that measures the pressure difference before and after the filter, The second life prediction line is created such that the rate of change of the second life prediction line, which is measured by a sensor different from the sensor used to create the first life prediction line, is matched to the rate of change of the second life prediction line, which is measured by a sensor different from the one used to create the first life prediction line, which is obtained from the initial value and the value during correction measurement of either the airflow sensor or the differential pressure sensor. A clean air device that manages the filter based on the first or second life prediction line. <Part 2> The clean air device according to <Part 1>, which corrects the starting point of the first life prediction line and the ending point of the second life prediction line to coincide with each other, and the starting point of the second life prediction line and the ending point of the first life prediction line to coincide with each other. <Part 3> The clean air device described in <Part 2>, which corrects the first life prediction line and the second life prediction line so that they overlap with each other. <Part 4> The management of the aforementioned filter is performed using the corrected life prediction line and the value of the airflow sensor as described in <Part 3> of the clean air device. <Part 5> The aforementioned correction measurement is performed during the initial periodic inspection of the clean air device described in <Part 1>. <Part 6> The clean air device described in <Part 1> is a ceiling-mounted FFU, and the airflow sensor and differential pressure sensor are provided only in a portion of the ceiling-mounted FFU installed on the same ceiling. <Part 7> The clean air device described in <Part 4> has a first warning value associated with the first life prediction line or the second life prediction line, and issues a warning when the value of the airflow sensor falls below the first warning value. <Part 8> The clean air device described in <7> has a second warning value associated with the first or second life prediction line, and issues an alarm when the value of the airflow sensor falls below the second warning value. <Part 9> The clean air device described in <Item 8> requests the arrangement of replacement parts when the aforementioned alarm is triggered. <Part 10> The clean air device according to <Part 1>, having a display function for the first life prediction line, the second life prediction line, or the corrected life prediction line. <Part 11> The clean air device described in <Part 1> determines abnormal data when the deviation of one of the data from the differential pressure sensor or the wind speed sensor from the corrected life prediction line differs significantly from the deviation of the data from the other sensor from the corrected life prediction line. <Part 12> The clean air device described in <Part 1> proposes checking and correcting the usage and installation conditions when it determines that the aforementioned data is abnormal. <Part 13> A clean air system having a clean air device as described in any one of items <1> to <12>, and transmitting data from the airflow sensor and data from the differential pressure sensor to a separate computing device via a communication line or electrical wiring. <Part 14> The calculation unit collects information from airflow sensors and differential pressure sensors from a number of clean air devices and performs bulk ordering, bulk procurement, or bulk production of the filters as described in <Part 13> of the clean air system. <Part 15> The calculation device collects information from airflow sensors and differential pressure sensors from a number of clean air devices, and reduces the amount of filter inventory, as described in <Part 14> of the clean air system. [Explanation of Symbols]

[0124] 1: Filter 10: Top casing 11: Side enclosure 12: Front enclosure 13: Lower enclosure 20: Legs 21: Differential pressure sensor 22: Primary pressure port 23: Secondary pressure port 24: Wind speed sensor 25: Abnormal data 26: Programmable Display 27:PLC 100: Safety Cabinet 101: Workbench 102: Workspace 103: Front shutter 104: Work opening 104a: Front slit 105: Rear route 105a: Rear slit 106: Intake fan 107: Airflow rectifier 108: Exhaust vent 109: Upper Chamber 110: Exhaust HEPA filter 111: HEPA filter for air vents 112: Inflow airflow 113: Outflow airflow 114: Airflow 115: Lighting 116: Germicidal lamp 300: Communication line 301: Arithmetic device 310: Collected data 311: Processed data 500: Rectifier plate

Claims

1. In a clean air system having a filter, An airflow sensor that measures the airflow after passing through the filter, The filter has a differential pressure sensor that measures the pressure difference before and after the filter, The second life prediction line is created such that the rate of change of the second life prediction line, which is measured by a sensor different from the sensor used to create the first life prediction line, is matched to the rate of change of the second life prediction line, which is measured by a sensor different from the one used to create the first life prediction line, which is obtained from the initial value and the value during correction measurement of either the airflow sensor or the differential pressure sensor. A clean air device that manages the filter based on the first or second life prediction line.

2. The clean air device according to claim 1, wherein the starting point of the first life prediction line and the ending point of the second life prediction line coincide with each other, and the starting point of the second life prediction line and the ending point of the first life prediction line coincide with each other.

3. The clean air device according to claim 2, wherein the first life prediction line and the second life prediction line are corrected so that they overlap each other.

4. The clean air device according to claim 3, wherein the management of the filter is performed by the corrected life prediction line and the value of the airflow sensor.

5. The clean air device according to claim 1, wherein the correction measurement is performed during the initial periodic inspection.

6. The clean air device according to claim 1, wherein the clean air device is a ceiling FFU, and the airflow sensor and the differential pressure sensor are provided only on a portion of the ceiling FFU installed on the same ceiling.

7. The clean air device according to claim 4, which has a first warning value associated with the first life prediction line or the second life prediction line, and which issues a warning when the value of the airflow sensor falls below the first warning value.

8. The clean air device according to claim 7, which has a second warning value associated with the first or second life prediction line, and which issues an alarm when the value of the airflow sensor falls below the second warning value.

9. The clean air device according to claim 8, which requests the arrangement of replacement parts when the aforementioned alarm is issued.

10. The clean air device according to claim 1, having a display function for any of the first life prediction line, the second life prediction line, or the corrected life prediction line.

11. The clean air device according to claim 1, wherein abnormal data is determined when the deviation of one of the data from the differential pressure sensor or the wind speed sensor from the corrected life prediction line differs significantly from the deviation of the data from the other sensor from the corrected life prediction line.

12. The clean air device according to claim 1, which, when it determines that the data is abnormal, proposes checking and correcting the usage and installation conditions.

13. A clean air system comprising a clean air device according to any one of claims 1 to 12, wherein data from the airflow sensor and data from the differential pressure sensor are transmitted to a separate computing device via a communication line or electrical wiring.

14. The clean air system according to claim 13, wherein the calculation device collects information from airflow sensors and differential pressure sensors from a number of clean air devices and performs bulk ordering, bulk procurement, or bulk production of the filters.

15. The clean air system according to claim 14, wherein the calculation device collects information from airflow sensors and differential pressure sensors from a number of clean air devices and reduces the amount of filter inventory.

Images