JPH07248132A - Natural convection type clean room - Google Patents

Abstract

PURPOSE:To effect air conditioning of a clean room where precision instruments which conflict with even sonic vibration exist, while promoting the effective utilization of energy. CONSTITUTION:A clean room 1 is provided with a ceiling plenum space 3 above it, a space 6 under the floor under it, and a return space 8 at a side, which jointly form a circulation route for air. In the lower part of the return space 8 a first condenser 12 which is a part of the condenser of a direct expansion refrigerator is installed and in the passageway of flow from the return space 8 to the ceiling plenum space 3 an evaporator 14 of the refrigerator is installed. The first condenser 12 serves as a heating source and the evaporator 14, as a cooling source and make the density of the air low and high so that the air positively circulates without any air-flowing machinery. Since the cooling source and the heating source exist in one and the same refrigeration system, this constitution promotes the effective utilization of energy and simplifies the air-conditioning equipment. Moreover, with no air-flowing machinery in use, the system is free of sonic vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clean room, and more particularly to a natural convection type clean room in which air is circulated only by a difference in air density without using an air circulation blower.

[0002]

2. Description of the Related Art In a general clean room, an air blower is installed in an air circulation system to circulate the air in the clean room to remove dust with a high-performance filter and control temperature with a cooling / heating coil.

In a state-of-the-art clean room, countermeasures against floor vibration are taken quite a lot, but they are not enough against sound wave vibration, so even sound wave vibration is disliked.
The environment for manufacturing equipment and analytical equipment is delayed. For example, in the photolithography process of exposing a circuit pattern of an integrated circuit onto a wafer, as the miniaturization of the circuit progresses year by year,
Even slight vibrations and air fluctuations are considered to be factors that lead to errors in positioning and the like, leading to a decrease in yield. In addition, a transmission electron microscope (TEM) that enables atomic level observation of crystals on a silicon wafer has a resolution of 1
Although it is extremely high, at or above Angstrom, it is said that image damage is caused by sound wave vibrations caused by noise generated from air blowers, compressors, and motors of air conditioning equipment.

[0004]

Therefore, in an environment where even the above-mentioned sound wave vibration is disliked, it is necessary to construct a natural convection type clean room which does not have a blower for circulating the fine air. When an air circulation system using natural convection is to be constructed, the air in the circulation path is cooled and heated by the air cooling source and the heating source (or only the cooling source). In this case, both an independent cold heat source and an independent heat source are required, the air conditioning equipment becomes large-scale, and the increase in energy consumption due to repeated heating and cooling becomes a problem.

The present invention has been made in view of the above points, and an evaporator and a condenser of the same refrigeration system are simultaneously installed in an air circulation path to achieve effective use of energy and simplification of air conditioning equipment. That is the purpose.

[0006]

To achieve the above object, according to claim 1, an upper space above the ceiling and a lower space below the floor,
A clean room having a return space on the side, wherein air supplied from the space above the ceiling to the inside of the clean room through a filter is configured to be able to circulate again from the space under the floor to the space above the ceiling to the space above the ceiling. In a clean room, a part of the condenser of the direct expansion type refrigerator is installed in the lower part of the return space in the circulation path, and the evaporator of the refrigeration machine is installed in the flow path from the return space to the above-ceiling space in the circulation path. A natural convection type clean room is provided, which is characterized by installing a vessel. Note that the direct expansion refrigerator as referred to in the present invention,
It refers to a vapor compression refrigerator using a dry evaporator.

In this case, the evaporator may be installed in the lower part of the space above the ceiling as described in claim 2, and also in claim 3
As described in (1), it may be installed in both the flow path from the return space to the space above the ceiling and the lower part of the space above the ceiling in the circulation path.

Further, as described in claim 4, the direct expansion type refrigerator may be configured to control the temperature of each of the evaporators by controlling the capacity thereof. In this respect, as described in claim 5, a plurality of evaporators are installed in the lower space of the ceiling, and the temperature of each evaporator is individually controlled by controlling the electronic expansion valve of each of these evaporators. You may.

When performing the above-mentioned temperature control, as described in claims 6 and 7, a temperature sensor is installed in the space above the ceiling, and the temperature sensor is controlled based on the detection signal of this temperature sensor. Or, in addition, this temperature sensor
As described in claim 8, it may be installed in a clean room.

[0010]

The condenser of the direct expansion refrigerator constitutes a heating source such as a heating coil, and the evaporator constitutes a cooling source such as a cooling coil. Since the condenser is installed in the lower part of the return space in the circulation path, it heats the air circulated from the underfloor space to the return space to reduce the density of the air and enhance the buoyancy.

The air that has risen in the return space is cooled by the evaporator installed in the flow path from the return space to the space above the ceiling, the density increases, and the buoyancy up to that point decreases, resulting in a clean room. It is supplied to the inside. Therefore, according to the present invention, a circulating flow is formed by increasing the density difference of air. In this way, by using the cooling source and the heating source in the same refrigeration system, it is possible to effectively use energy and simplify the air conditioning equipment.

As shown in the Mollier diagram shown in FIG. 1, since the heat absorption amount and the heat radiation amount are not the same in the evaporator and the condenser, the temperature of the circulating air rises when the air is circulated in the closed system. Occurs. Therefore, since it is necessary to release the residual heat (X in FIG. 1) to the outside, a part of the condenser of the direct expansion refrigerator is installed in the circulation path as described above.

According to a second aspect of the present invention, the evaporator is installed in the lower part of the space above the ceiling, and the air cooled by the evaporator directly drops through the filter into the clean room.

Further, in the present invention, since the flow path from the return space to the space above the ceiling in the circulation path and the evaporator of the refrigerator are respectively installed in the lower space of the space above the circulation path, the evaporation installed in the flow path. The evaporator can be used for rough cooling, and the evaporator installed under the space above the ceiling can be used for precision cooling.

In the fourth aspect, since the temperature of the evaporator is controlled by controlling the capacity of the direct expansion refrigerator, it is possible to easily control the temperature of the air supplied into the clean room. In this case, in claim 5, a plurality of evaporators are installed in the lower part of the ceiling space, and the temperature of the evaporator in the lower part of the ceiling space is controlled by controlling the electronic expansion valves of these individual evaporators. It is easy to make the temperature distribution in the clean room uniform.

Then, based on the detection signal of the temperature sensor installed in the space above the ceiling, the capacity of the direct expansion refrigerator is controlled as in claim 6, or the control of the electronic expansion valve as in claim 7. The temperature control in the clean room is automatically and appropriately performed by the configuration described above. Further, as described in claim 8, if the temperature sensor is installed in the clean room, the temperature can be controlled more practically, that is, according to the actual situation.

[0017]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 2 shows the outline of the construction of the first embodiment. In this embodiment, a closure formed by a wall W or the like is used. A filter 2 such as a ULPA filter is provided above the clean room 1 formed in the space (upper part in the closed space).
The space 3 above the ceiling is formed through the. The filter 2 partitions the ceiling of the clean room 1 into appropriate areas, is installed in each partition, and is composed of a plurality of filters as a whole. The above-ceiling space 3 constitutes an air supply chamber. An underfloor space 6 is formed on the lower side of the clean room 1 (a lower part in the closed space) via a floor plate 5 having a large number of vent holes 4. This underfloor space 6
Constitutes the underfloor chamber. A return space 8 connecting the above-ceiling space 3 and the underfloor space 6 is formed on a side portion of the clean room 1 through an appropriate partition wall 7.

Next, the direct expansion refrigerator used in this embodiment will be described. The high-temperature and high-pressure refrigerant compressed by the compressor 11 installed outside the closed space, for example, outdoors, is stored in the return space 8. It is sent to the 1st condenser 12 installed and intervened in the lower part, the circulating air is heated in the lower part of the return space 8, and then it is sent to the 2nd condenser 13 installed outdoors, and the residual heat is generated by forced ventilation. Is being released.

On the other hand, an evaporator 14 is installed and interposed in the flow path between the return space 8 and the space above the ceiling 3 substantially above the return space 8 and the second condenser. The refrigerant whose temperature has been lowered through 13 is the electronic expansion valve 1
It is configured to be transferred to the evaporator 14 via 5 and then circulated to the compressor 11. Therefore,
In the lower part of the return space 8, the air warmed by the first condenser 12 is cooled when passing through the evaporator 14 and dust is removed when passing through the filter 2, and is supplied into the clean room 1. It has become so.

A temperature sensor 21 is provided in the space 3 above the ceiling.
Is installed, and the detection signal of this temperature sensor 21 is
It is input to the controller 22. This controller 2
2 is an inverter 23 based on the input detection signal.
The capacity of the refrigeration system is controlled by controlling the rotation speed of the compressor 11 via the.

The first embodiment is configured as described above, and the air under the return space 8 is heated by the first condenser 12 to have a low density and buoyancy, so that the air inside the return space 8 rises. Then, it is cooled by the evaporator 14 interposed in the flow path between the return space 8 and the space 3 above the ceiling, and as a result, the density of the air increases, and the air is supplied into the clean room 1 through the filter 2. To be done. Then, the underfloor space 6 is passed through the ventilation hole 4 of the floor plate 5.
It is discharged into the inside, is heated again in the lower part of the return space 8 and circulates in the above-mentioned path. That is, clean room 1
Regarding the air inside, the first condenser 12 and the evaporator 14 positively change the density difference of the air without having a blowing system,
It circulates from the underfloor space 6 to the return space 8 to the space above the ceiling 3 to the clean room 1.

Therefore, even if the clean room 1 has a precision device E such as a manufacturing device or an analytical device which is averse to sound wave vibration, it is not affected and the desired function can be exerted. Further, since the heating source and the cooling source that give the air density are the first condenser 12 and the evaporator 14 in the same refrigeration system, respectively, the energy can be effectively used and the air-conditioning equipment can be extremely effective. It has been simplified.

Since the temperature of the air supplied to the above-ceiling space 3 is adjusted by the capacity control based on the rotation control of the compressor 11 by the inverter 23, the temperature inside the clean room 1 can be set and maintained at a predetermined temperature. Further, such control is automatically performed by the controller 22 based on the signal detected by the temperature sensor 21 installed in the space 3 above the ceiling.

In the first embodiment, as shown in FIG. 2, the evaporator 14 is installed obliquely to cool the warm air circulating from the upper part of the return space 8 and directly to the filter 2. Since it is configured to be lowered, it is possible to effectively use the space in the absence of a blower system device and to supply the cooled circulating air to the upper surface of the filter 2.

By the way, the driving force of the air flow in the natural circulation loop as in the above embodiment is buoyancy as described above, and this buoyancy is created by repeating heating and cooling. On the other hand, when air passes through a coil or a high-performance filter in such a natural circulation loop, a frictional resistance (passing resistance) occurs, which acts as a force that blocks the flow of air. The steady state is where the buoyancy and the frictional force are balanced. The circulating air volume in the natural circulation loop is thus determined.

In the above embodiment, the buoyancy is the difference between the air density in the return space 8 and the air density in the clean room 1, and the effective height of the natural circulation system, that is, the clean room 1,
It is determined by the total height of the effective portions of the space above the ceiling (supply plenum chamber) 3 and the space under the floor (return plenum chamber) 6. Further, the frictional force is governed by the air flow velocity (the area ratio between the return space 8 and the clean room 1). Therefore, the blowing conditions in the clean room 1 are determined by the circulation conditions based on these parameters.

For example, when the area ratio of the clean room 1 to the return space 8 is 1, the return space 8
The wind velocities inside and inside the clean room 1 become equal. When the area ratio is smaller than 1, the wind speed in the clean room 1 is faster than in the return space 8. On the contrary, when the area ratio is larger than 1, the wind speed in the clean room 1 is higher than that in the return space 8. Become slow. In the case of a general clean room, since the area ratio is around 10, the wind speed in the clean room is 1/10 of the return space.

Qualitatively, under the above reasons, when it is desired to increase the blowing air velocity in the clean room, the temperature difference between the heating and cooling parts of the air is increased, and the clean room is increased to increase the area ratio. It should be small.
More specifically, referring to the above embodiment, the height of the clean room 1 is increased, or the first condenser 12 and the evaporator 1 are used.
The air velocity in the clean room 1 can be increased by increasing the temperature difference from the clean room 1 or by decreasing the area ratio between the return space 8 and the clean room 1.

Next, the second embodiment will be described. In the second embodiment, the evaporator in the first embodiment is divided into a plurality of parts, and the divided evaporators are also divided into individual parts. The filter is installed horizontally on the upper surface of the filter, and is, so to speak, a unitized structure.

That is, as shown in FIG. 3, the refrigerant flow path from the compressor 11 is appropriately branched, and the first evaporator 14a,
The second evaporator 14b is connected to the first evaporator 14a and the second evaporator 14b, and the first evaporator 14a and the second evaporator 14b are horizontally installed in parallel with the filters 2a and 2b. The remaining structure is similar to that of the first embodiment,
In FIG. 3, members and device configurations that are referred to by the same reference numerals as those in the first embodiment are the same as those in the first embodiment.

According to the second embodiment having such a structure, the warm air circulated from the upper part of the return space 8 is transferred as it is into the space 3 above the ceiling, and then the first evaporator 14a and the second evaporator 14a. After being cooled by the vessel 14b, the density is increased and the particles are directly supplied to the clean room 1 through the filters 2a and 2b.

In this case, each of the first evaporator 14a and the second evaporator 14b is independently provided with an electronic expansion valve 15a, 15b.
Is provided, the first evaporator 14a and the second evaporator 14a
By controlling the capacity of the evaporator 14b, the temperature of the supply air to the clean room 1 can be adjusted for each unit, and the temperature distribution in the clean room 1 can be made uniform or individually controlled. Is possible.

Also in the second embodiment, the space 3 above the ceiling is also used.
Although the temperature sensor 21 is installed in the above, the temperature of the air before passing through the evaporator is detected in this case. Of course, the present invention is not limited to this, and a temperature sensor may be provided in the clean room 1, and a plurality of temperature sensors may be provided, and the first evaporator 14a and the second evaporator 14 may be provided based on the respective detection signals.
The electronic expansion valves 15a and 15b of b may be individually controlled. By installing a plurality of temperature sensors in this way, it is easy and automatic to make the temperature distribution uniform.

[0034]

According to the first and second aspects of the present invention, it is possible to achieve effective use of energy and simplification of air conditioning equipment by performing the cooling source and the heating source in the same refrigeration system. It is possible to effectively use the heat energy that has been discarded to the outside as waste heat. Further, since the air circulation system is a natural convection type that utilizes the difference in air density, it can be applied to a clean room where there are devices that dislike sound wave vibration. According to the third aspect, since the evaporator installed in the flow path can be used for rough cooling and the evaporator installed in the lower part of the space above the ceiling can be used for precise cooling, the temperature can be appropriately adjusted according to the environment. It is even possible. According to the fourth aspect, it is further possible to easily control the temperature of the supply air into the clean room by controlling the capacity of the direct expansion refrigerator.

According to claim 5, it is possible to easily realize uniform temperature distribution in the clean room. According to claims 6 and 7,
According to the eighth aspect, the temperature control described in claims 4 and 5 is automatically and appropriately performed, and according to the eighth aspect, more practical temperature control is performed on the natural convection type clean room.

[Brief description of drawings]

FIG. 1 is a Mollier diagram for explaining the present invention.

FIG. 2 is an explanatory diagram showing an outline of the configuration of the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an outline of a configuration of a second embodiment of the present invention.

[Explanation of symbols]

 1 Clean Room 2 Filter 3 Ceiling Space 6 Underfloor Space 8 Return Space 11 Compressor 12 1st Condenser 13 2nd Condenser 14 Evaporator 21 Temperature Sensor 22 Controller 23 Inverter

Claims (8)

[Claims] 1. A clean room having an above-ceiling space at an upper part, an under-floor space at a lower part, and a return space at a side, wherein air supplied from the under-ceiling space to the clean room through a filter is discharged from the under-floor space. In a clean room configured to be able to circulate again to the above-ceiling space through the return space, a part of the condenser of the direct expansion refrigerator is installed in the lower part of the return space in the circulation path, and the return in the circulation path is arranged. A natural convection type clean room, characterized in that the evaporator of the refrigerator is installed in the flow path from the space to the space above the ceiling. 2. A clean room having an above-ceiling space at the top, an underfloor space at the bottom, and a return space at a side, wherein air supplied from the above-the-ceiling space into the clean room through the filter is from the underfloor space. In a clean room configured to be able to circulate again to the above-ceiling space via the return space, a part of the condenser of the direct expansion refrigerator is installed in the lower part of the return space in the circulation path, and at the bottom of the above-ceiling space. Characterized in that the evaporator of the refrigerator is installed,
Natural convection type clean room. 3. A clean room having an above-ceiling space at the top, an underfloor space at the bottom, and a return space at a side, wherein air supplied into the clean room from the above-the-ceiling space through the filter is from the underfloor space. In a clean room configured to be able to circulate again to the above-ceiling space through the return space, a part of the condenser of the direct expansion refrigerator is installed in the lower part of the return space in the circulation path, and the return in the circulation path is arranged. A natural convection type clean room, characterized in that the evaporator of the refrigerator is installed in each of a flow path from the space to the space above the ceiling and a space below the space above the ceiling. 4. The natural convection type clean room according to claim 1, 2 or 3, wherein the temperature of the evaporator is controlled by controlling the capacity of the direct expansion refrigerator. 5. A plurality of evaporators are installed in the lower space above the ceiling, and the temperature of the evaporator in the lower space above the ceiling is controlled by controlling an electronic expansion valve of each of these evaporators. The natural convection type clean room according to claim 2, 3 or 4. 6. The natural convection type clean room according to claim 4, characterized in that the capacity of the direct expansion refrigerator is controlled based on a detection signal of a temperature sensor installed in the space above the ceiling. . 7. The natural convection type clean room according to claim 5, wherein the electronic expansion valve is controlled based on a detection signal of a temperature sensor installed in the space above the ceiling. 8. The natural convection type clean room according to claim 6, wherein the temperature sensor is installed in the clean room.