JP2002089919A - Ceiling structure for clean room - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceiling structure for clean room which can fix the quantity of the air discharged into an attic space of a clean room. SOLUTION: In this ceiling structure for clean room, a holding frame 40 having a U-shaped cross section is arranged so as to surround the opening of a ceiling frame 36 and a closing plate 42 is put on the opening so as to close the opening. The closing plate 42 is held in a vertically movable state and, at the same time, is urged in the direction in which the plate 42 closes the opening by means of coil springs 50. The plate 42 ascends when the differential pressure between the clean room 12 and the attic space 24 of the clean room becomes a fixed value or higher. When the plate 42 ascends, a flow passage having a U-shaped cross section is formed between the edge section 42A of the plate 42 and the holding frame 40 and the air in the clean room 12 is discharged into the attic space 24 through the flow passage. When the differential pressure becomes higher, the gap 44A between the edge section 42A and frame 40 becomes narrower and a fixed quantity of air is always discharged into the attic space 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceiling structure of a clean room, and more particularly to a ceiling structure of a clean room requiring high cleanliness, such as a semiconductor manufacturing factory.

[0002]

2. Description of the Related Art A plurality of fan filter units (hereinafter referred to as "F") are provided on a ceiling of a clean room such as a semiconductor manufacturing plant.
FU ". ) Is installed, and the air in the space above the ceiling is purified by the FFU and supplied to the room. But,
The FFUs are not necessarily placed densely on the ceiling surface, and may be thinned out to reduce equipment costs and running costs. In this case, in order to prevent air before cleaning of the space above the ceiling from flowing into the room, the FF
In the thinning space in which U is thinned, a closing plate for completely shutting off the space above the ceiling and the room is installed.

However, when a closing plate is installed in a thinning space where the FFU is thinned out, a vortex is generated below the closing plate, and dust stays in a region where the vortex is generated.
This causes a problem that the cleanliness in the clean room is reduced.

Therefore, a method of suppressing the generation of eddy currents by installing a ventilation resistor such as a punching panel or various filters in the thinning space and discharging the air in the stagnation area to the space above the ceiling through the ventilation resistor. Was proposed. In this case, the air volume of the air discharged into the space above the ceiling is adjusted by changing the aperture ratio by sliding two punched panels that are placed one on top of the other. Alternatively, the adjustment is made by changing the combination of filters.

[0005]

However, in the ventilation resistor having the conventional structure, when the pressure balance between the space above the ceiling and the clean room is lost, the amount of air discharged to the space above the ceiling changes, and as a result, In addition, there is a disadvantage that the air flow blown out from the FFU as a laminar flow is disturbed, and the cleanliness in the clean room is reduced.

[0006] The present invention has been made in view of such circumstances, and a clean room in which the amount of air discharged to the ceiling space can be kept constant irrespective of fluctuations in the pressure difference between the clean room and the space above the ceiling. It is intended to provide a ceiling structure.

[0007]

In order to achieve the above object, the present invention provides an opening formed in a ceiling of a clean room, and a holding member having a U-shaped cross section which is arranged so as to surround the opening. A frame, a closing plate disposed so as to cover the opening, and a side portion disposed with a predetermined gap inside the holding frame, the closing plate being held vertically movably in the holding frame; Urging means for urging the closing plate in a direction to close the plate, the closing plate resists the urging force of the urging means when a differential pressure between the upper and lower sides of the ceiling surface exceeds a certain value. A clean room ceiling structure that discharges air in the clean room to a space above the ceiling through a channel having a U-shaped cross section formed between the holding frame and the holding frame.

According to the present invention, the closing plate rises from the opening against the urging force of the urging means when the pressure difference above and below the ceiling surface exceeds a certain value. Then, when the closing plate is raised, a channel having a U-shaped cross section is formed between the closing plate and the holding frame, and the air in the clean room is discharged to the space above the ceiling through the channel. At this time, as the differential pressure increases, the amount of rise of the closing plate also increases.However, when the amount of rise of the closing plate increases, the width of the gap above the flow path formed in a U-shaped cross section decreases. Become. As a result, even if the differential pressure fluctuates, the air volume of the air discharged from the clean room to the space above the ceiling becomes constant, and the inside of the clean room can always be kept at a high cleaning degree.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a clean room ceiling structure according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of a clean room facility 10. As shown in the figure, on the ceiling surface 16 of the clean room 12, a lattice-shaped ceiling frame 36 is suspended by a plurality of suspension bolts 13, 13,..., And a plurality of FFUs 14, 14,. Are arranged. Then, clean air is supplied into the clean room 12 by the FFU 14 and is sucked into the underfloor space 20 from the grating floor 18 together with dust in the clean room 12.

A part of the air sucked into the underfloor space 20 is cooled by the dry coil 21 and then returned to the return space 2.
2 and returned to the space 24 above the ceiling. Another part is exhausted to the outside by the exhaust duct 34, and another part is sent to the air conditioner 28 via the return air duct 26. The air sent to the air conditioner 28 is mixed with fresh air taken in from the outside air take-in duct 30, adjusted to a predetermined temperature and humidity, and then supplied to the under-ceiling space 24 via the air supply duct 32. . Then, it is purified again by the FFU 14 and supplied into the clean room 12.

FIG. 2 shows a space 2 above the ceiling of the clean room 12.
4 is a perspective view showing a configuration of FIG. As shown in the figure, FFUs 14 are thinned out in a lattice space 37A of a ceiling frame 36 formed in a lattice shape. FFU14
Is mainly composed of a casing, a fan, and a filter.
4 is sucked into the casing and the HEPA
It blows out into the clean room 12 through the filter.

On the other hand, the ventilation resistor 3 is provided in the thinning space 37B of the ceiling frame 36 in which the FFU 14 is thinned.
8 are installed. The ventilation resistor 38 suppresses generation of a vortex by discharging air in a stagnant area generated near the ceiling surface of the clean room 12 to the space 24 above the ceiling, and has the following configuration.

FIGS. 3 and 4 are a perspective view and a front sectional view showing the structure of the ventilation resistor 38, respectively.

The thinning space 37B formed by the ceiling frame 36 has a rectangular opening as the clean room 1
2 is formed on the ceiling surface. The ceiling frame 36 is formed in a convex cross section, and a rectangular holding frame 40 formed so as to surround the thinning space 37B is attached to the flange portion 36A.

The holding frame 40 is formed in a U-shaped cross section, and a closing plate 42 is disposed inside the holding frame 40 so as to cover the opening of the thinning space 37B. This closing plate 42
It is formed in a rectangular plate shape slightly larger than the opening of the thinning space 37B, and the side portion 42A is formed by being bent in a U-shaped cross section. A side portion 42A of the closing plate 42 having a U-shaped cross section is provided with a predetermined gap 44B inside the holding frame 40 also having a U-shaped cross section.
It is fitted with.

The side 42A of the closing plate 42 has
Are formed in a plurality of places at predetermined intervals. Each guide hole 46 has a holding frame 4
A bolt 48 vertically attached to the bracket 0 is inserted, and the closing plate 42 is guided by the bolt 48 so as to be vertically movable inside the holding frame 40. And
When the closing plate 42 moves up and down, the thinning space 3
The opening of 7B opens and closes.

That is, when the closing plate 42 is lowered and the side portion 42A comes into close contact with the bottom portion 40A of the holding frame 40, the opening of the thinning space 37B is closed. On the other hand, when the closing plate 42 rises, predetermined gaps 44A and 44C are formed above and below the side portion 42A. This upper and lower gap 44
A and 44C communicate with each other via a gap 44B. As a result, a channel having a U-shaped cross section is formed between the clean room 12 and the space 24 above the ceiling, and the thinning space 37B is opened. Thus, the opening of the thinning space 37B is opened and closed by the closing plate 42 moving up and down.

Here, a coil spring 50 is interposed between the bolt head 48A and the closing plate 42 for the bolt 48 that guides the closing plate 42 up and down.
The closing plate 42 is urged by the coil spring 50 in a direction (downward) to close the opening of the thinning space 37B. For this reason, normally, the closing plate 42 is provided with the thinning space 37B.
Only when the pressure difference between the clean room 12 and the space 24 above the ceiling rises above a certain value, the opening rises against the urging force of the coil spring 50 to open the thinning space 37B. .

Note that the bolt 48 is attached to the holding frame 40.
Is screwed into a bolt hole 52 formed in the bottom surface portion 40A of the base member, and the amount of protrusion can be changed by screwing into the bolt hole 52. By adjusting the amount of protrusion of the bolt 48, the amount of expansion and contraction of the coil spring 50 can be adjusted, and the urging force urged by the coil spring 50 can be adjusted. That is, the condition of the differential pressure required to raise the closing plate 42 can be adjusted.

The operation of the ceiling structure of the clean room according to the present embodiment configured as described above is as follows.

When the pressure difference between the clean room 12 and the space 24 above the ceiling is equal to or less than a predetermined value, the opening of the thinning space 37B is closed by the closing plate 42. That is, the side portion 42 </ b> A of the closing plate 42 is
A is in close contact with A.

In this state, when the pressure difference between the clean room 12 and the space 24 above the ceiling exceeds a predetermined value, the closing plate 42 rises against the urging force of the coil spring 50. When the closing plate 42 rises, the side 4 of the closing plate 42
Predetermined gaps 44A and 44C are formed above and below 2A.
The upper and lower gaps 44A and 44C communicate with each other through a gap 44B formed in advance with the holding frame 40. As a result, a flow having a U-shaped cross section is formed between the clean room 12 and the space 24 above the ceiling. A path is formed. Then, the clean room 12 passes through the U-shaped channel.
The air inside is discharged to the space 24 above the ceiling.

Here, the closing plate 42 is a coil spring 5
When the pressure difference between the clean room 12 and the under-the-ceiling space 24 fluctuates, it is moved upward and downward in accordance with the fluctuation amount of the pressure difference. And this closing plate 42
Moves up and down, the width of the gap 44C formed on the upper side of the side portion 42A also changes accordingly. That is, the side 42
The gap 44C formed on the upper side of A becomes narrower as the amount of rise of the closing plate 42 increases (as the differential pressure increases). As described above, when the differential pressure increases, the gap 44C formed on the upper side of the side portion 42A is automatically narrowed (because the flow path is narrowed). The air volume is always kept constant. Thereby, the air in the stagnation area can be discharged to the space 24 above the ceiling without disturbing the flow of the air blown out from the FFU 14 as a laminar flow.

The closing plate 42 automatically closes the opening of the thinning space 37B when the differential pressure becomes equal to or less than a predetermined value.
Even if the FFU 14 is stopped, the air before the cleaning of the under-ceiling space 24 does not enter the room 12.

As described above, according to the ceiling structure of the clean room of the present embodiment, the flow path of the air discharged to the space 24 above the ceiling can be automatically restricted by the differential pressure.
Irrespective of fluctuations in the pressure difference between the clean room 12 and the ceiling space 24, air with a constant air volume can always be discharged to the ceiling space. Thus, the air in the stagnation area can be discharged to the space 24 above the ceiling without disturbing the flow of the air blown out from the FFU 14 as a laminar flow, and the cleanliness in the clean room can always be kept high.

[0027]

As described above, according to the present invention,
Since the flow path of the air to be discharged to the space above the ceiling can be automatically narrowed by the differential pressure, air with a constant air volume can always be discharged to the space above the ceiling regardless of the differential pressure fluctuation.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a clean room facility.

FIG. 2 is a perspective view showing a configuration of a space above a ceiling of a clean room.

FIG. 3 is a perspective view showing a configuration of a ventilation resistor.

FIG. 4 is a front sectional view showing a configuration of a ventilation resistor.

[Explanation of symbols]

10: clean room equipment, 12: clean room, 1
3 ... hanging bolts, 14 ... fan filter unit (FF
U), 16: ceiling surface, 24: space above the ceiling, 36: ceiling frame, 36A: flange portion, 37A: lattice space, 37
B: thinning space, 38: ventilation resistor, 40: holding frame, 40A: bottom part, 42: closing plate, 42A: side part, 4
4A to 44C: gap, 46: guide hole, 48: bolt,
50 ... Coil spring

Claims (2)

[Claims] An opening formed in a ceiling surface of a clean room, a holding frame having a U-shaped cross section arranged to surround the periphery of the opening, and an opening arranged to cover the opening. The sides are arranged with a predetermined gap inside the holding frame,
A closing plate movably held up and down in the holding frame; and a biasing means for biasing the closing plate in a direction to close the opening, wherein the closing plate has a vertical difference of the ceiling surface. When the pressure exceeds a certain value, the pressure rises against the urging force of the urging means, and the air in the clean room is formed through a U-shaped channel formed between the holding frame and the holding frame. A clean room ceiling structure that discharges to the space above the ceiling. 2. The clean room ceiling structure according to claim 1, wherein said urging means is capable of adjusting an urging force for urging said closing plate.