JPH02150645A - Control system of clean room - Google Patents

Abstract

PURPOSE:To make the flow of air change proportionately to variations of the condition of control by using as a standard a schedule line specifying duct pressures which are obtainable by multiplying the values for modifying the opening given to a damper by correction factors appropriate to the positions of the actual opening of the damper and by taking the pressures between both sides of the damper as being constant against changes in the pressure between both sides of a filter and by specifying suitable values as the correction factors. CONSTITUTION:When a supply air duct pressure P3 is low, the state point decided by the measurable pressure P1 between both sides of a filter and by a supply air duct pressure P3 is located in the zone (3) under a schedule line Is, and in a nonlinear compensator 16 the table IG of basic correction factors shifts upward in parallel and the correction factors G by which the values U1 for modifying the opening are to be multiplied become large. A supplying air velocity which decreases due to decrease of the pressure between both sides of a supply damper 2A can be increased up to an appropriate value by modifying the opening to a larger value. When a supply air duct pressure P3 is high, the state point decided by the measurable pressure P1 between both sides of the filter and by a supply air duct pressure P3 is located in the zone (b) above the schedule line Is, and in a nonlinear compensator 16 the table IG of basic correction factors shifts downward in parallel and the correction factors G by which the values U1 for modifying the opening are to be multiplied become small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a clean room control system that controls air conditioning conditions in a clean room by adjusting the opening degree of an attached damper.

[Conventional technology]

In recent years, the demand for clean rooms has been increasing in cutting-edge industries such as microelectronics and biotechnology. Clean rooms can be broadly divided into biological clean rooms, which require sterile conditions such as operating rooms, laboratory animal breeding rooms, and bioengineering laboratories, and biological clean rooms, which require sterile conditions such as operating rooms, laboratory animal breeding rooms, and biotechnology laboratories, and biological clean rooms, which require sterile conditions such as those used in electronics and precision machinery factories, where there are few suspended particles indoors. It is divided into industrial clean rooms, which require cleanliness.

In such a lean room, it is desired that the room pressure and ventilation rate are always maintained at set values, and a quick response to changes in the set values is required.

FIG. 5 is a schematic configuration diagram of a conventional clean room control system, and is shown as an example of application to a biological clean room.

For example, when culturing bacteria in a biological clean room, the inside of the clean room is set to negative pressure in order to prevent the bacteria from escaping to the outside. In addition, to prevent the invasion of bacteria from outside,
Set the clean room to positive pressure. On the other hand, when raising animals in a clean room, it is desirable to increase the amount of ventilation. In the control system shown in the figure, the set room pressure is set to a desired constant value, and only the set ventilation amount is changed depending on whether the clean room is used or not. That is, when the clean room is used, the set ventilation rate is increased, and when it is not used, it is decreased.

In the figure, 1 is a clean room, 2 is a supply air damper installed in the air supply passage to the clean room 1, 3 is a return air damper installed in the air supply passage from the clean room 1, and 4 is a unit that detects the supply air wind speed. 5 is the air supply side anemometer, 5 is the air side anemometer that detects the air flow speed, 6 is the blower, 7 is the exhaust fan, 8
9 is an air supply duct, 9 is an exhaust duct, 10 is a differential pressure transmitter that detects the room pressure in the clean room, and 11 is a set room pressure Y that is predetermined by inputting the detected room pressure Y1 detected by this differential pressure transmitter 10. 1set, a controller that varies the set return air wind speed This is a setting device that allows you to change the setting of YZsat value.

Set air supply air speed Y2 to the air supply damper 2 via the setting device 12
．． ．． . is set large when the clean room 1 is used, and set small when the clean room 1 is not used. Then, based on this set air supply wind speed Y zsat, this set air speed Y 2
set and the detected supply air speed Y2 given via the anemometer 4
Adjust the opening degree of the supply air damper 2 (V
AV control) is performed. On the other hand, the return air damper 3 adjusts its opening based on the set return air speed X1 (VAV control ) is to be carried out.

Next, the operation of the family tree control system configured as described above will be explained. That is, it is assumed that the clean room 1 is currently in an unused state. At this time, a small value of the supply air speed Y ziat is set for the supply air damper 2, and the ventilation amount in the clean room 1 is controlled by VAV control of the supply air damper 2 based on this set supply air speed Yzsl. maintains a small value corresponding to the set supply air speed Y 2 set. On the other hand, the room pressure in the clean room 1 is also determined by the return air damper 3 based on the set air speed X.
The set room pressure Y+sat is maintained by VAV control.

From this state, if the value of the supply air speed Y2□, which is supplied to the supply air damper 2, is set to a large value in order to put the clean room 1 into use, this set supply air velocity Y! In response to the increase in set, the opening degree of the supply air damper 2 is VAV controlled in the direction of opening,
The amount of air supplied to the clean room 1 begins to increase. Due to this increase in the supply air volume, the room pressure in the clean room 1, that is, the detected room pressure Y to the controller 11, changes to the set room pressure Y.
1sat, and the value of the set air velocity X1 to the return air damper 3 increases in accordance with this room pressure difference. Then, in response to the increase in the set air velocity
In combination with the VAV control, the ventilation amount in the clean room 1 will eventually be maintained at a large value corresponding to the set wind speed Y2, (2) with the set room pressure Yli constant.

FIG. 6 is a block diagram showing the room pressure control system in this control system, and if a difference occurs in the detected room pressure Yl with respect to the set room pressure Y If@t, the set room pressure Y +set
The set air speed X1 to the return air damper 3 is varied according to the difference between the set air speed X and the detected room pressure Y1, and the set air speed The return air damper 3 is subjected to VAV control, and the room pressure of the clean room 1 is controlled to match the set room pressure Y15et. Here, in the block shown by the dashed dotted line, VA
A V cascade loop will be constructed.

[Problem to be solved by the invention]

However, according to such a conventional control system, when the set air supply air speed Y25, t for the air supply damper 2 is changed, the ventilation amount is actually adjusted according to the set air speed Y2.1, assuming that the room pressure Y Is + qt is constant. The problem is that it takes a considerable amount of time to secure it. According to the inventor's research, this time varies depending on the conditions, but it requires 5 to 10 minutes. This problem arises largely due to the construction of a VAV cascade loop within the family main loop in the room pressure control system.

In other words, when VAV controlling the damper according to the set wind speed, the time constant of the VAV cascade loop depends on the motor speed that changes the damper opening and the detection (response) speed of the anemometer that detects the actual wind speed. !゛Determined,
The delay in the anemometer's response speed becomes a bottleneck, increasing its time constant.

When the return air damper 3 is subjected to VAV control, the VA
The time constant of the V cascade loop is thicker than the time constant of the family main loop (VAV cascade loop time constant > family main loop time constant), and as a result, the VAV control time in the VAV cascade loop becomes longer. , in the room pressure control system, for example, the set air supply air speed Y 2 s e
When the detected chamber pressure Y begins to increase due to a change in the setting of t, the set value of the air velocity X1 for the return air damper 3 increases in accordance with the chamber pressure difference. The return air damper 3 is subjected to VAV control in response to this set air speed X1.
Since the time constant of the cascade loop is larger than the time constant of the family main loop, the detection chamber pressure Y1 continues to increase.
The value of the return air wind speed X, which corresponds to the value of This means that it takes a long time to secure a constant value. Also, V of this return air damper 3
As the AV control time becomes longer, the VAV control time of the air supply damper 2 also becomes longer in order to adjust the fluctuating ventilation amount.

In order to solve this problem, we need to calculate <VAV
! Without using IJ'a, the opening degree change value according to the difference in supply air speed and the opening degree change value according to the room pressure difference are directly supplied to the supply air damper 2 and the return air damper 3, and the degree adjustment is performed between them. There are ways to do this.

However, the damper has strong nonlinearity between its opening degree and the amount of air passing through it (wind speed), resulting in a characteristic as shown in FIG. 7, for example. On the other hand, if the opening change value is given as a constant depending on the amount of change in the control conditions, it is not possible to obtain a uniform change in the passing air volume according to the amount of change regardless of the actual opening position of the damper. . For example, taking the supply air damper 2 as an example, the actual opening position of the supply air damper 2 is 5.
When it is 0% (see Figure 8), if the opening change is θa based on the opening change value corresponding to the difference in supply air speed, then
A change in supply air velocity of Ql is obtained.

However, when the supply air damper 2 is at an actual opening position of θ1 exceeding 50%, for example, the change value Q2 of the supply air speed obtained for a change in the opening of θa becomes smaller than Ql.

Further, for example, a filter 14 attached to the supply air damper 2
As the clogging in the filter 14 progresses, the front and rear pressures in the filter 14 increase. This increase in the longitudinal pressure at the filter 14 causes the longitudinal pressure at the air supply damper 2 to decrease, and the air supply air velocity obtained depending on the opening position of the air supply damper 2 decreases.

Although the above explanation has been given by taking the supply air damper 2 as an example, the same problem occurs in the return air damper 3 as well.

[Means to solve the problem]

The present invention has been made to solve these problems, and is configured to multiply the opening change value provided to a damper attached to a clean room by a correction coefficient corresponding to the actual opening position of the damper, and Based on the schedule line that determines the duct pressure that can maintain the damper's longitudinal pressure constant against changes in the longitudinal pressure of the filter attached to the damper, it is determined by the actual filter's longitudinal pressure and the actual duct pressure. If the state point is in a region below the schedule line, the correction coefficient is made large, and if the state point is in a region above the schedule line, the correction coefficient is made small.

[Effect]

Therefore, according to the present invention, by appropriately determining the correction coefficient to be multiplied according to the actual damper opening position, the change in the passing air volume according to the amount of change in the control condition is made equal regardless of the actual damper opening position. be able to obtain it. In addition, if the duct pressure is determined according to the schedule line in response to changes in the filter front and rear pressure, the front and rear pressure of the damper can be kept constant, but the state point determined by the actual filter front and rear pressure and the actual duct pressure is If the schedule line is located below the schedule line, it is assumed that the duct pressure is insufficient, and the above correction coefficient is increased; if it is located above the schedule line, the duct pressure is excessive. Assuming that , the above correction coefficient is set to be small.

〔Example〕

Hereinafter, the clean room control system according to the present invention will be explained in detail. FIG. 1 is a schematic configuration diagram showing one embodiment of this control system, and FIG. 2 is a block diagram showing the room pressure/air supply air speed control system. In these figures, the same reference numerals as in FIGS. 5 and 6 indicate the same components, and their explanations will be omitted.

In this control system, the detected supply air wind speed Y2. detected by the supply air anemometer 4. The detection chamber pressure Y detected by the differential pressure transmitter 10 is given to the controller IIA, and
A set air supply air speed Y 2 set is given to the IA depending on whether the clean room 1 is used or not. Then, in the controller IIA, the detected chamber pressure Y1 and the set chamber pressure Y1set are compared, and the opening change values UI and U2 corresponding to the chamber pressure difference are obtained in the matrix section 15. The nonlinear compensation unit 16
and 17, and are applied as corrected opening degree change values U and U2'' to the supply air damper 2A and the return air damper 3A.In addition, in the controller IIA, the detected supply air speed Y2 and the set supply air speed Y. , t are compared, and the opening change values U2 and U2 corresponding to the difference in supply air speed are obtained in the matrix section 15, and nonlinear compensation is performed for the obtained opening change values U1 and U2. Corrections are made in sections 16 and 17, and the corrected opening change values U1'' and U2'' are applied to the supply air damper 2A and the return air damper 3A. That is,
The controller IIA determines the opening change values Ul' and UZ' based on both the room pressure difference and the supply air speed difference and corrects them in the nonlinear compensators 16 and 17, and applies them to the supply air damper 2A and the return air damper. It is given to 3A.

The following formula is a determinant for determining the opening change values U1 and U2 in the matrix section 15, where F is a control parameter as a P (proportional) component, and F2 is I (integral).
It is a control parameter as a component, and in this example, it is given as follows.

In the above equation, the values of the control parameters F+ and Ft vary depending on the scale of the system, etc., but are basically determined by calculation on the premise that the following operations are performed. That is, the supply air damper 2A and the return air damper 3A are adjusted so that the supply air speed YZset, which is set to be changed, is adjusted to the damper opening degree that can maintain the room pressure Yls@ constant, and changes due to disturbances, etc. The control parameters F+, The value of Fz is determined by calculation. In addition, the opening change value U,
and U2 are based on the 50% opening position of the supply air damper 2A and return air damper 3A, and regardless of the actual opening position of the supply air damper 2A and return air damper 3A, the difference between the room pressure and the supply air speed difference is It is output as a constant depending on both values.

The nonlinear compensators 16 and 17 include potentiometers (
Actual opening positions θi and θj of the supply air damper 2A and return air damper 3A (not shown) are detected, and the front and rear pressures P1 of the filters 14 and 13 are detected by the differential pressure transmitters 18 and 19.
and P2, and the air supply duct pressure P3 and exhaust duct pressure P4 detected by the differential pressure transmitters 20 and 21 are given. The nonlinear compensators 16 and 17 are provided with a basic correction (gain) coefficient table 6 as shown by the solid line in FIG. is set,
A correction coefficient G determined by this basic correction coefficient table I is multiplied by the opening change values U1 and U2 according to the actual opening positions of the supply air damper 2A and the return air damper 3A.

Then, this basic correction coefficient table I is determined according to the state point determined by the filter front and rear pressure P1 and the air supply duct pressure P3 and the state point determined by the filter front and rear pressure P2 and the exhaust duct pressure P4, as indicated by the dashed line shown in the figure. As shown by the two-dot chain line, it moves in parallel in the vertical direction.

FIG. 4 is a schedule line that defines the set value of the air supply duct pressure that can maintain the front and rear pressure of the supply air damper 2A constant against changes in the front and rear pressure of the filter 14 attached to the supply air damper 2A. That is, when the front and rear pressure of the filter 14 increases due to its clogging, the front and rear pressure of the air supply damper 2A can be maintained constant by increasing the air supply duct pressure according to this schedule line Is. can. This schedule line Is is set in the nonlinear compensator 16. Then, if the state point determined by the actually measured filter front and rear pressure P1 and air supply duct pressure P3 is in the region (■) below this schedule line Is, the basic correction coefficient table I6 is moved upward in parallel. If the correction coefficient G is large and lies in the upper region ■, then
The correction coefficient G is made small by parallel movement downward. A schedule line similar to this is also determined in the nonlinear compensator 17, and its basic correction coefficient table is determined according to the region where the state point determined by the actually measured filter front and rear pressure P2 and exhaust duct pressure P3 is located. I
, are moved in parallel in the vertical direction.

On the other hand, the air supply duct pressure P3 detected by the differential pressure transmitter 20 is
It is also given to the controller 22, and in this controller 22, the set air supply duct pressure P
In comparison with 3set, the blower 6 is controlled by an inverter in order to reduce the duct pressure to zero. Further, the exhaust duct pressure P4 detected by the differential pressure transmitter 21 is also given to the controller 23, and the set exhaust duct pressure P4s is set in the controller 23.
In comparison with AT, the exhaust fan 7 is controlled by an inverter in order to reduce the duct pressure to zero. and,
The pressure P1 across the filter 14 and the pressure P2 across the filter 13 detected by the differential pressure transmitters 18 and 19 are applied to the controllers 22 and 23, which are arranged in parallel between the air supply duct 8 and the exhaust duct 9. In each clean room, the pressures before and after the filter attached to the supply air damper and the pressures before and after the filter attached to the return air damper are also given to the controllers 22 and 23 in the same way, and the set air supply duct pressure is determined by the average value of these pressures. P. , and the set exhaust duct pressure P4° are determined.

Next, the operation of the control system configured as described above will be explained.

That is, it is assumed that the clean room 1 is currently in an unused state. At this time, the ventilation amount in the clean room 1 is maintained at a small value according to the set air supply air velocity Y 2 set and the room pressure in the clean room 1 is maintained at the set room pressure Y + set. In order to put clean room 1 into use from this state, controller I
When the value of the set air supply wind speed Y2s■ to the IA is increased, this set air supply wind speed Y2□.

and the detected supply air speed Y2 are compared, and the matrix section 15 obtains opening degree change values Ul and U2 according to the difference in the supply air speed.

Then, the obtained opening degree change values U1 and U2 are corrected in the nonlinear compensators 16 and 17,
The corrected opening degree change values Ul' and U2+ are given to the supply air damper 2A and the return air damper 3A.

Here, to describe the correction operation using the nonlinear compensator 16 as an example, the air duct pressure in the air duct 8 is P 3s
The air supply duct pressure P 3tat is maintained at
If the state point determined by the front and rear pressures P1 and P1 at the filter 14 is on the schedule line s, the basic correction coefficient table 2 shown by the solid line in FIG. 3 is adopted. That is, depending on the actual opening position θi of the air supply damper 2A at that time, the correction coefficient G according to this correction coefficient table I becomes the opening change value U1.
You will be able to take advantage of it. For example, if the actual opening position θi of the supply air damper 2A is 50%, there is no need to perform correction, so the correction coefficient G is multiplied by 1.0, and the actual opening position θi is 50%.
If i exceeds 50%, the change value of the actual supply air speed according to the opening change value U will be small, so in order to equalize the change value, the change value should be greater than 1°0. The value is multiplied by a correction factor. Furthermore, if the actual opening position θi is less than 50%, the change value of the actual supply air speed according to the opening change value U1 will be large, so in order to equalize the change value, A correction coefficient having a value smaller than 1.0 is multiplied.

On the other hand, the state point determined by the air supply duct pressure Pff$Gt and the longitudinal pressure P1 at the filter 14 is not necessarily on the schedule line s. That is, in the case where no other clean room is installed in parallel to the clean room 1, if the value of the set air supply duct pressure P3set in the controller 22 is increased based on the schedule line Is in accordance with the increase in the front and rear pressure PI of the filter I4, the supply can be improved. Qi damper 2A
It is possible to prevent a decrease in the supply air speed by keeping the front and rear pressures constant.

However, in reality, many clean rooms are installed in parallel to the clean room 1, and the average value of the pressures before and after the air supply side filters attached to these clean rooms is, for example,
The set air supply tallit pressure P3□ is determined. For this reason, even though the longitudinal pressure P1 at the filter I4 is high, the actual air supply duct pressure P3 may be lower than the air supply duct pressure determined by the schedule line Is. Furthermore, with respect to the front and back pressure P1 of the filter 14, the actual air duct pressure P3 may be higher than the air duct pressure determined by the schedule line Is. If the air supply duct pressure P3 is low, the longitudinal pressure at the air supply damper 2A will be low, and the air supply wind speed will decrease. Moreover, if the air supply duct pressure P3 is high, the air supply damper 2A
The front and rear pressure at the pump increases and the supply air speed increases.

On the other hand, when the air supply duct pressure P3 is low, the state point determined by the actually measured filter front and rear pressure P1 and the air supply duct pressure P3 is in the area below the schedule line IS.
Located in As a result, in the nonlinear compensator 16,
The basic correction coefficient table (6) moves upward in parallel, and the correction coefficient G by which the opening degree change value U1 is multiplied becomes large. Therefore, in response to a decrease in the front and rear pressure in the supply air damper 2A, that is, a shortage of air supply duct pressure, the decreasing supply air speed can be increased to an appropriate value by increasing the opening change.

Further, when the air supply duct pressure P3 is high, the state point determined by the actually measured filter front and rear pressure P1 and the air supply duct pressure P3 is located in the region ■ above the schedule line Is,
In the nonlinear compensator 16, basic correction coefficient table 1.
is translated downward, and the correction coefficient G by which the opening change value U1 is multiplied becomes small.

Therefore, in response to an increase in the front-rear pressure in the air supply damper 2A, that is, an excessive air supply duct pressure, the increasing air supply air velocity can be reduced to an appropriate value by minimizing the change in opening degree.

In addition, although the operation|movement regarding the nonlinear compensation part 16 was demonstrated above, the same correction|amendment is performed also in the nonlinear compensation part 17 with respect to the opening change value U2.

Then, the corrected opening change value Ul' and [J%, which have been appropriately corrected in this way, are given to the supply air damper 2A and the return air damper 3A, and the opening change value Ul' and In response to U2°, supply air damper 2A and return air damper 3
The opening degree adjustment of A is performed at the same time. That is,
The opening degree of the supply air damper 2A is controlled in the open direction so as to increase the supply air speed, and the opening degree of the return air damper 3A is controlled in the open direction so as to suppress an increase in room pressure due to this increase in the supply air speed. become something that Then, the supply air damper 2A and the return air damper 3A adjust the corrected opening degree change values Ul' and UZ.
If the opening degree is changed in accordance with ', the air supply air speed can be maintained at the set air supply air speed Y 2 s e t to maintain a constant room pressure Y1□1 by achieving a balance here. In other words, the changed supply air speed Y
The damper opening can be reliably secured as 1st constant.
The supply air damper 2A and the return air damper 3A are combined at the same time, and the setting of the supply air speed can be changed extremely quickly.

In this embodiment, the basic correction coefficient table is moved vertically in parallel depending on the state point determined by the filter front and rear pressures and the duct pressure, but the movement does not necessarily have to be parallel.

〔Effect of the invention〕

As explained above, according to the clean room control system according to the present invention, the opening change value provided to the damper attached to the clean room is multiplied by a correction coefficient corresponding to the actual opening position of the damper, and Based on the schedule line that defines the duct pressure that can keep the damper's longitudinal pressure constant against changes in the longitudinal pressure of the attached filter, the state point determined by the actual filter longitudinal pressure and the actual duct pressure is determined. If the schedule line is below the schedule line, the above correction coefficient is made large, and if it is above the schedule line, the above correction coefficient is made small, so the correction coefficient is multiplied according to the actual opening position of the damper. By appropriately setting , it becomes possible to obtain uniform changes in the amount of passing air according to the amount of change in control conditions regardless of the actual opening position of the damper, and to prevent the front and rear pressure of the filter due to clogging etc. Even if the duct pressure is insufficient or excessive with respect to the change in the control conditions, it becomes possible to obtain an even change in the amount of passing air according to the amount of change in the control conditions.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing one embodiment of the clean room control system according to the present invention, Fig. 2 is a flow diagram showing the room pressure/air supply air speed control system in this control system, and Fig. 3
The figure shows the basic correction coefficient table set in the nonlinear compensation section of this control system, and Figure 4 shows that the front and rear pressure of the supply air damper can be kept constant with respect to the front and rear pressure of the filter attached to the supply air damper. FIG. 5 is a schematic configuration diagram showing a conventional clean room control system; FIG. 6 is a block diagram showing a room pressure control system in this control system; FIG. The figure shows the relationship between damper opening degree and passing air volume (wind speed).
The figure shows the change in the amount of passing air when the opening degree of the damper is changed at a constant rate regardless of the opening position of the damper. 1...Clean room, 2A...Air supply damper, 3A
... Return air damper, 4... Supply air side anemometer, 10.18
．． 19.20.21... Differential pressure transmitter, IIA... Controller, 12... Setting device, 15... Matrix section, 16.1'? ...Nonlinear compensation section.

Claims (1)

[Claims] A clean room whose air conditioning conditions are controlled by adjusting the opening of an attached damper, and an opening change that provides an opening change value for adjusting the opening to the damper according to the amount of change in the air conditioning condition of the clean room. a first correction means for multiplying the opening change value provided by the opening change value providing means by a correction coefficient corresponding to the actual opening position of the damper; Based on the schedule line that defines the duct pressure that can maintain the damper's front and rear pressure constant against pressure changes, the state point determined by the actual filter front and rear pressure and the actual duct pressure is below this schedule line. A clean room control system comprising: second correction means that increases the correction coefficient when the area is in the upper area, and reduces the correction coefficient when the area is in the upper area.