Clean bench

Abstract

To provide a clean bench which enables reduction of a time for adjusting a wind speed.SOLUTION: A clean bench 1 sends outside air suctioned by a fan 20 to a working space 7 through filters 19, 21 and includes: wind speed detection means 12 which detects a wind speed of airflow sent into the working space 7; storage means 26 which stores a fan output value of the fan 20; and control means 24 which stores the fan output value recorded when the wind speed detected by the wind speed detection means 12 is stabilized in the storage means 26 and activates the fan 20 at the fan output value recorded when the wind speed is stabilized and stored in the storage means 26 during a next operation.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a clean bench, particularly to the adjustment of the wind speed of the air fed into its working space.

Background Art

[0002] In a clean bench capable of performing operations such as mixing two or more kinds of drugs while maintaining a sterile state, the working space is filled with clean air passing through a filter, and the working space is maintained at a positive pressure to prevent contamination by dust, dirt, floating microorganisms, etc.

[0003] In a clean bench, outside air is fed into the working space through a pre-filter, a fan, and a main filter. The pre-filter and the main filter have different mesh sizes. Without a pre-filter, relatively large dust etc. from the outside air adheres to the main filter and quickly clogs, making it unusable. Therefore, the pre-filter is used to remove dust etc. in the air in advance and pass the cleanest possible air through the main filter. The pre-filter is made of non-woven fabric, can be washed with water, is inexpensive, and is easy to remove. The main filter has finer mesh than the pre-filter, and a high-performance air filter (HEPA filter, ULPA filter, etc.) at a level where the clean bench can meet JIS standards is used. The main filter is more expensive than the pre-filter, difficult to remove, and has weak durability.

[0004] If the output of the fan is suddenly increased to the maximum, the main filter will be overloaded and may malfunction or its failure may be accelerated. Also, since the wind speed depends on the clogging condition of the pre-filter and the main filter, the output of the fan cannot be preset. For this reason, a wind speed sensor is provided on the downstream side of the main filter, and the output of the fan is gradually increased. When the detected wind speed of the wind speed sensor reaches the preset wind speed, the output of the fan is fixed.

[0005] Patent Document 1 describes an air velocity control device for a clean bench that controls the rotational speed of a blower so that the air velocity on the downstream side of a filter detected by an air velocity sensor becomes a preset air velocity value.

[0006] When the air velocity decreases due to clogging of the pre-filter or main filter, it takes a long time to reach the target air velocity. For example, when there was no clogging, it took 4 minutes and 30 seconds to reach the target air velocity, but when it became clogged, it took 7 minutes and 39 seconds. If no measures were taken against clogging, there was a problem that each time, the adjustment time until the air velocity reached the target air velocity was long, resulting in a great waste of time.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a clean bench capable of shortening the air velocity adjustment time.

Means for Solving the Problems

[0009] In order to solve the above problems, the present invention in a clean bench that sends outside air sucked in by a fan into a working space through a filter, an air velocity detection means for detecting the air velocity of the air flow sent into the working space; a storage means for storing the fan output value of the fan; control means for storing the fan output value when the air velocity detected by the air velocity detection means is stable in the storage means, and starting the fan with the fan output value when the air velocity is stable stored in the storage means at the next operation; is provided.

[0010] It is preferable that the fan output value when the state in which the current wind speed detected by the wind speed detection means is within a predetermined range of the target wind speed is maintained for a predetermined time is defined as the fan output value when the wind speed is stable.

[0011] A pre-filter is provided on the upstream side of the fan, a main filter is provided on the downstream side of the fan, and the wind speed detection means is provided on the downstream side of the main filter, and it is preferable to detect the wind speed of the air sent into the working space through the pre-filter, the fan, and the main filter.

Advantages of the Invention

[0012] According to the present invention, at the time of the next operation, since the fan is started with the fan output value when the wind speed was stable in the previous time, it is not affected by clogging of the filter, and has the effect of shortening the adjustment time of the wind speed until the wind speed reaches the target wind speed.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0015] Figure 1 shows a clean bench 1 according to an embodiment of the present invention. The clean bench 1 includes a main body 3, a fan unit 4, and a shutter 5 on a work table 2 having four legs 2a.

[0016] The work table 2 is configured such that an operator sits on a chair (not shown), slightly opens the shutter 5, puts a hand inside the main body 3, and performs necessary work. A differential pressure gauge 2b for indicating which of a pre-filter 19 and a main filter 21 described later is clogged is provided at the front edge of the work table 2. The differential pressure gauge 2b measures the pressure in the space between the pre-filter 19 and the fan 20, stores in advance the pressure P1 when the pre-filter 19 is clogged and the pressure P2 when the main filter 21 is clogged, and indicates that the pre-filter 19 is clogged if the measured pressure is equal to or lower than P1, and indicates that the main filter 21 is clogged if the measured pressure is equal to or higher than P2. With this differential pressure gauge 2b, clogging of the pre-filter 19 and the main filter 20 can be quickly detected.

[0017] The main body 3 has a rectangular box shape surrounded by left and right side walls 3a, 3b and a rear wall 3c, and is open at the front. As shown in FIG. 2, inside the main body 3, a ceiling plate 6 is provided, and a work space 7 is formed above the ceiling plate 6 and the work table 2. Above the ceiling plate 6 of the main body 3, a front cover 8 and a top cover 9 are provided. An air intake 9a is formed in the top cover 9.

[0018] An air outlet 6a from which the air flow from the fan unit 4 blows out is formed in the ceiling plate 6 of the main body 3, and an illumination LED 10, a germicidal lamp 11, and an air velocity sensor 12 are provided at the edge of the air outlet 6a. The air velocity sensor 12 is a known sensor that receives the air flow flowing out from the air outlet 6a and detects its flow velocity.

[0019] On the front end face of the right side wall 3b of the main body 3, an operation display unit 13 and a shutter position detection sensor 14 are provided. As shown in FIG. 1, on the operation display unit 13, in order from the top, a fan button 15 for turning the fan 20 on and off, a lamp button 16 for turning the illumination LED 10 on and off, and a UV button 17 for turning the sterilization lamp 11 on and off are provided. As shown in FIG. 3, the shutter position detection sensor 14 is provided with two detection parts 14a and 14b, the first and the second, in order from the bottom in the direction in which a detection piece 18 provided on the lower shutter 5b of the shutter 5 extends. As shown in FIG. 4(a), when only the first detection part 14a detects the upper end part of the detection piece 18, the shutter 5 is in the closed position. As shown in FIG. 4(b), when the first detection part 14a and the second detection part 14b detect the detection piece 18, the shutter 5 is in the working position. As shown in FIG. 4(c), when neither the first detection part 14a nor the second detection part 14b detects the detection piece 18, it is determined that the shutter 5 is in the open position.

[0020] The fan unit 4 is arranged on the ceiling plate 6 of the main body 3, and is provided with a pre-filter 19, a fan 20, and a main filter 21 in order from the top. The pre-filter 19 is provided at the air intake 9a of the top cover 9, and filters the air taken in from the air intake 9a. As the pre-filter 19, one using a synthetic fiber non-woven fabric or the like can be adopted. The fan 20 sucks in the air taken in from the pre-filter 19 and blows it out, and a centrifugal fan or the like can be adopted. The main filter 21 filters the air blown out from the fan 20. As the main filter 21, a mini-pleat type HEPA filter, a ULPA filter or the like can be adopted.

[0021] The shutter 5 is made of transparent glass or plastic and opens and closes the opening of the main body 3, and is composed of an upper shutter 5a and a lower shutter 5b. As shown in FIG. 3, the upper shutter 5a and the lower shutter 5b are each provided with roller units 22 at both side ends. The roller unit 22 has a first roller 22a that is rotatable around a horizontal first axis and a second roller 22b that is rotatable around a second axis perpendicular to the first axis and perpendicular to the surface of the shutter 5. By rolling along the left and right walls 3a, 3b of the main body 3, the shutter 5 can move up and down.

[0022] As shown in FIG. 2, the upper shutter 5a covers the upper half of the opening of the main body 3, and its upper end is located inside the front cover 8 in a state where the upper half of the opening is closed. The upper shutter 6b can be stopped by a stopper (not shown) in a state where the upper half of the opening is closed. The lower shutter 5b covers the lower half of the opening, and its upper end overlaps the upper shutter 5a in a state where the lower half is closed. The lower shutter 5b can be stopped by a stopper (not shown) in a state where the lower half of the opening is closed. A handle 23 is provided below the surface of the lower shutter 5b. When the handle 23 is held and pulled up, it moves upward together with the upper shutter 5a and is housed inside the front cover 8. The gap between the upper shutter 5a and the lower shutter 5b can prevent the entry of outside air by providing a sealing material (not shown) at the lower end of the upper shutter 5a or the upper end of the lower shutter 5b.

[0023] In the case of a conventional single shutter, as shown by the dashed-dotted line in FIG. 2, since it protrudes from the top cover 9, if the ceiling of the room where the clean bench is installed is low, the shutter will hit the ceiling. For this reason, the height of the ceiling of the room where the conventional clean bench is installed is limited. Also, although it is possible to prevent it from hitting the ceiling, in this case, the opening height of the shutter becomes low, and the work space cannot be sufficiently opened. On the other hand, in the present embodiment, the shutter 5 is composed of an upper shutter 5a and a lower shutter 5b. When the lower shutter 5b is pulled upward from the closed position shown in FIG. 2(a), it passes through the working position in FIG. 2(b) and is stored inside the front cover 8 as shown in FIG. 2(c). Therefore, it does not protrude from the top cover 9, the height of the ceiling of the room where the clean bench 1 is installed is not limited, and the opening of the main body 3 can be fully opened to clean the work space 7 and the like.

[0024] FIG. 5 shows the control block of the clean bench 1. The control unit 24 is composed of a computer including a central processing unit (CPU) 25 and a storage unit 26. The detection signals of the shutter position detection sensor 14 and the wind speed sensor 12, and the on-off signal of the operation display unit 13 are input to the central processing unit 25. The illumination LED 10 and the germicidal lamp 11 are connected to the central processing unit 25 and are controlled to be turned on and off by a command from the central processing unit 25 based on the on-off signal of the operation display unit 13. The fan 20 is connected to the fan drive unit 27, and the fan drive unit 27 is connected to the central processing unit 25. The fan drive unit 27 controls the on-off of the fan 20 by a command from the central processing unit 25. A buzzer 28 is connected to the central processing unit 25.

[0025] Next, with reference to the flowchart of FIG. 6, the operation of the control unit 24 when adjusting the wind speed of the clean bench 1 will be described.

[0026] The wind speed adjustment controls the fan output to automatically adjust the blowing speed directly below the main filter 21 within a predetermined range, and maintains the work space 7 at a certain air cleanliness level. The target wind speed is set to 0.5 m / s.

[0027] When the fan button 15 is turned on, the central processing unit 25 outputs the initial fan output to the fan driving unit 27 at step 101 to start the fan 20. The initial fan output is the fan output when the wind speed was stable in the storage unit 26 if there was a previous operation and the fan output at that time was stored. Also, if there was no previous operation and the fan output when the wind speed was stable was not stored in the storage unit 25, the fan output is set to 35% as the default value.

[0028] At step 102, after waiting for 20 seconds to elapse after the fan is started, at step 103, reading of the current wind speed detected by the wind speed sensor 12 is started and wind speed adjustment is performed. Here, the fan output increases or decreases stepwise with an increase or decrease amplitude according to the difference between the current wind speed and the target wind speed as follows to prevent damage to the main filter 21. Specifically, when the current wind speed is greater than the target wind speed (+), the fan output is decreased, and when the current wind speed is less than the target wind speed (-), the process of increasing the fan output is performed. The maximum value during adjustment of the fan output is 80%, but the maximum value at startup is 60% for safety even if the previous fan output was 80%. [Table 1]

[0029] In step 104, during the wind speed adjustment, it is determined whether the fan output is 30% or less. This is to check for the omission of attaching the pre-filter 19. That is, if the pre-filter 19 is omitted, even with a low fan output, the target wind speed can be exceeded. So, during the wind speed adjustment, for example, when the current wind speed is +20% or more higher than the target wind speed, the fan output will decrease. However, when the fan output drops to 30% or less, it can be determined that the pre-filter has been omitted. When the fan output becomes 30% or less, in step 105, the buzzer 28 is notified of the fan output lower limit error. When the fan output exceeds 30%, in step 106, it is determined whether the current wind speed is within ±10% of the target wind speed. If the current wind speed is not within ±10% of the target wind speed, the wind speed adjustment in step 103 continues. If the current wind speed is within ±10% of the target wind speed, from step 107 to step 110, the fluctuations above and below the current wind speed are stabilized.

[0030] In step 107, if the current wind speed exceeds the target wind speed, in step 108, the current wind speed is obtained as the upward fluctuation value, and the fan output is decreased. In step 109, when the current wind speed is lower than the target wind speed, in step 110, the value of the current wind speed is obtained as the downward fluctuation value, the upward and downward fluctuation values are compared, and the fan output closer to the target wind speed is selected. Then, in step 111, the fan output is fixed and the fan 20 is operated. Also, in step 107, if the current wind speed does not exceed the target wind speed and is below the target wind speed, in step 112, the current wind speed is obtained as the downward fluctuation value, and the fan output is increased. In step 113, if the current wind speed becomes higher than the target wind speed, in step 114, the value of the current wind speed is obtained as the upward fluctuation value, the upward and downward fluctuation values are compared, and the fan output closer to the target wind speed is selected. In step 111, the fan output is fixed and the fan 20 is operated.

[0031] During the fan output fixed operation in step 111, if in step 115 the fan output becomes 30% or less, then in step 116 a buzzer 28 is notified of a fan output lower limit error. If the fan output exceeds 30%, then in step 117 it is determined whether the current wind speed is within ±10% of the target wind speed. If the current wind speed is not within ±10% of the target wind speed, the wind speed adjustment in step 103 is continued. If the current wind speed is within ±10% of the target wind speed, then in step 118, after waiting for 3 minutes to elapse since the fan output was fixed, the fan output at that time is stored in the storage unit 26 in step 119 as the stable fan output, and the fan output fixed operation in step 111 is performed.

[0032] According to the wind speed adjustment of the above embodiment, during the next operation, the fan is started with the fan output value when the previous wind speed was stable, so it is not affected by clogging of the filter, and the wind speed adjustment time until the wind speed reaches the target wind speed can be shortened.

[0033] During fan operation, if the shutter position detection sensor 14 detects that the shutter 5 is fully closed, it is determined that the operation has been aborted, the fan operation is forcibly stopped, and if it is determined that the front cover 8 has been opened by a microswitch (not shown), the fan operation is forcibly stopped. If the current wind speed of the wind speed sensor 12 does not fall within the specified range of the target wind speed even after 10 minutes have elapsed since the start of the fan operation, it is considered a fan operation timeout error.

[0034] The lighting LED 10 is turned on or off by operating the lamp button 16 of the operation display unit 13. When the shutter 5 is in the closed position by the shutter position detection sensor 14, the operation of the lamp button 16 is not accepted and the lighting LED 10 is not turned on. When the shutter 5 is in the open position during fan operation, the lighting LED 10 is turned off, and when the shutter 5 returns to the working position, the lighting LED 10 is turned on. Also, when the shutter 5 is in the closed position, the lighting LED 10 is turned off. In the standby state, even if the shutter 5 is in the open position while the lighting LED 10 is on, it remains in the on state.

[0035] The germicidal lamp 11 is turned on or off by operating the UV button 17 of the operation display unit 13. When the UV button 17 is pressed once, it lights up constantly. When it is pressed twice, it lights up with a timer and automatically turns off after the set time has elapsed. When it is pressed three times, it turns off. The germicidal lamp 11 is designed not to light up simultaneously with the illumination LED 10. Also, the germicidal lamp 11 has a safety function so that the operator does not receive UV irradiation. That is, when the shutter 5 is in a position other than the closed position, the operation of the UV button 17 is not accepted and it does not light up. Also, when the shutter 5 is in the open position during the lighting of the germicidal lamp 11, it turns off. Also, when it is determined by a microswitch (not shown) that the shutter 5 has been opened, the power supply to the germicidal lamp 11 is cut off.

[0036] The present invention is not limited to the above-described embodiment, and various changes and modifications are possible.

Explanation of Signs

[0037] 1... Clean bench 2... Work table 3... Main body 4... Fan unit 5... Shutter 12... Wind speed sensor 19... Prefilter 20... Fan 21... Main filter 24... Control unit 25... Central processing unit 26... Memory unit 27... Fan drive unit

Claims

1. In a clean bench that sends outside air sucked in by a fan into a work space through a filter, wind speed detection means for detecting the wind speed of the air flow sent into the work space; storage means for storing the fan output value of the fan; control means for storing the fan output value when the wind speed detected by the wind speed detection means is stable in the storage means, and starting the fan with the fan output value when the wind speed is stable stored in the storage means during the next operation; A clean bench comprising the above.

2. The clean bench according to claim 1, wherein the fan output value when the state in which the current wind speed detected by the wind speed detection means is within a predetermined range of the target wind speed is maintained for a predetermined time is defined as the fan output value when the wind speed is stable.

3. A pre-filter is provided on the upstream side of the fan, a main filter is provided on the downstream side of the fan, the wind speed detection means is provided on the downstream side of the main filter, and the clean bench according to claim 1 or 2, which detects the wind speed of the air sent into the work space through the pre-filter, the fan, and the main filter.

Images