JP4712910B1 - Precision air conditioner - Google Patents

Abstract

A precision air conditioner capable of controlling the amount of exhaust heat corresponding to the air conditioning load to be controlled while keeping the load of the refrigeration cycle constant.
In a precision air conditioner that introduces air in a chamber 12 installed in a clean room 10 and circulates the air in the chamber 12 at a set temperature, a condenser 31, from the discharge side to the suction side of a compressor 29, The expansion valve 35 and the evaporator 26 are sequentially connected, and the refrigeration cycle 25 having a hot gas bypass circuit 40 for flowing hot gas on the discharge side of the compressor 29 to the evaporator 26 and the evaporator 26 of the refrigeration cycle 25 are accommodated. A heat recovery unit 28 that introduces air from the chamber 12, air-conditions to a set temperature by the evaporator 26 and circulates to the chamber 12, and a condenser 31 of the refrigeration cycle 25 that is provided in the clean room 10 is accommodated, And the heat dissipation part 33 provided with the capability variable fan 32 which air-cools the condenser 31 with the air in the clean room 10 is provided.
[Selection] Figure 1

Description

  The present invention relates to a precision air conditioner that supplies and circulates precisely temperature-controlled air to a chamber that is an air conditioning target that houses an exposure apparatus or the like installed in a clean room.

  In the surrounding environment of the exposure apparatus for the liquid crystal glass substrate, since the glass substrate thermally expands due to temperature change, it is necessary to accurately control the air conditioning temperature (accuracy ± 0.01 to ± 0.1 ° C.).

  Such exposure equipment is installed in a chamber formed of partition walls in a clean room, and a precision air conditioner that is different from the clean room air conditioner is installed under the floor of the clean room. Is supplied and circulated to the chamber.

  This precision air conditioner is composed of a refrigeration cycle, and the air from the chamber is cooled to a temperature lower than a set temperature (for example, 17 ° C.) by an evaporator and heated to a set temperature (for example, 23 ° C.) by a reheat electric heater. The air is supplied and circulated to the chamber as conditioned air.

  Here, the heat absorption part, which is the evaporator of the refrigeration cycle, is installed in the clean room in order to air-condition the inside of the chamber, but the condenser as the heat radiation part is installed outside the clean room as an outdoor unit together with the compressor, and dissipates heat. The unit and the outdoor unit are connected by a refrigerant pipe to form an air-cooled air conditioner. Or, when installing a condenser that becomes a heat radiating unit under the floor of a clean room as a water-cooled type, a cooling water supply device is installed outside the clean room, and the heat radiating unit and the cooling water supply device are connected by water-cooled piping Various types have been proposed (Patent Document 1).

  However, the precise temperature control in which the conditioned air cooled to a temperature lower than the set temperature by the evaporator is heated to the set temperature by the reheat electric heater has a problem that the running cost of the electric heater increases.

  Therefore, as proposed in Patent Document 2, the hot gas of the refrigeration cycle is used, and this is supplied to the evaporator and added to the hot gas bypass for controlling the evaporation temperature. Proposed to install a condenser and to flow hot gas through the reheating condenser, to heat the air cooled by the evaporator with the reheating condenser and then to control the temperature precisely with the reheating electric heater. Has been.

  In Patent Document 2, the running temperature of the reheat electric heater can be reduced to some extent because the hot gas is flowed through the evaporator to control the evaporation temperature and the temperature of the conditioned air is controlled by the reheat condenser. It is impossible to precisely control the condensation temperature and evaporation temperature of the refrigeration cycle with hot gas bypass, and installation of a reheat electric heater is indispensable.

  On the other hand, in Patent Document 3, a reheat condenser is installed on the outlet side of the evaporator, and the hot gas is reheated by controlling the bypass amount of the hot gas with a three-way proportional control valve that operates pneumatically. It has been proposed that temperature control with good responsiveness can be realized with a condenser for use, thereby eliminating the need for a reheat electric heater.

  In Patent Document 3, the air from the chamber is cooled to a temperature lower by 5 ° C. than the set temperature by the evaporator and then heated to the set temperature by the condenser for reheating, and a reheat electric heater is unnecessary. The running cost can be reduced.

JP 2000-283500 A JP 2009-216332 A Japanese Patent No. 3283245

  However, in Patent Documents 1 to 3, cooling water is used for the condenser for exhaust heat recovery, and the cooling water supply device is separately installed outside the clean room and the cooling water pipe is used to radiate heat between the cooling water supply device and the condenser side. Work to connect the parts.

In particular, recent clean rooms are becoming larger in size, the height of the clean zone where process equipment such as exposure equipment is installed is close to 10 m, and the height of the return chamber under the floor is as high as 5 to 6 m. Moreover, the total floor area is tens of thousands m ^2, and chambers covering a large number of process devices are individually installed in the clean zone. The heat dissipating parts that dissipate the heat of each chamber are individually installed in the return chamber, while the cooling water supply device is installed outside the clean room. Inevitably, the connection requires work at a high place for connection, and also requires a great deal of labor such as keeping the cold water piping and measures against water leakage.

  Moreover, in patent documents 1-3, since the load of a refrigerating cycle is set to the capacity | capacitance corresponding to the largest air-conditioning load, and the refrigerant | coolant discharge pressure of a compressor is drive | operated as fixed, the exhaust heat of the refrigerant | coolant heat absorbed by the evaporator Controls the circulating amount of cooling water that flows to the condenser to match the amount of heat absorbed and the amount of exhaust heat. However, the water-cooled type, which cools the condenser with cooling water, can properly control the heat dissipation in the condenser when the air-conditioning load is large, but the cooling supplied to the condenser side when the air-conditioning load is small. There is a possibility that the water flow rate becomes extremely small and becomes less than the control range of the cooling water flow rate, which makes stable operation difficult.

  That is, in the temperature control of the chamber to be controlled, there are many cases where the temperature difference between the intake air and the blowing temperature is ± 2 ° C. or less and the air conditioning load is small. On the other hand, the cooling water temperature supplied to the condenser is about 18 ° C., and the cooling water temperature is lower than the refrigerant condensing temperature (around 70 ° C.). It becomes difficult to operate the refrigeration cycle stably and to adjust the amount of exhaust heat on the condenser side according to the air conditioning load.

  Accordingly, an object of the present invention is to provide a precision air conditioner that can solve the above-mentioned problems and can control the amount of exhaust heat corresponding to the air conditioning load of the chamber to be controlled while keeping the load of the refrigeration cycle constant.

In order to achieve the above object, the present invention provides a precision air conditioner for introducing air in a chamber to be air-conditioned installed in a clean room and circulating the air into the chamber at a set temperature.
A condenser, an expansion valve, and an evaporator are sequentially connected from the discharge side of the compressor to the suction side, and a refrigeration cycle having a hot gas bypass circuit for flowing hot gas on the discharge side of the compressor to the evaporator;
A heat recovery unit that houses the evaporator of the refrigeration cycle, introduces air from the chamber, air-conditions to a set temperature with the evaporator and circulates to the chamber;
A heat dissipating unit provided with a variable capacity fan that is provided in the clean room and accommodates the condenser of the refrigeration cycle, and air-cools the condenser with air in the clean room to keep the condensation pressure of the condenser constant. ,
It is a precision air conditioner equipped with.

  In the present invention, the refrigeration cycle, the heat recovery unit, and the heat dissipation unit are accommodated in the same casing.

  In the present invention, the hot gas bypass circuit includes a proportional control valve, and the heat recovery unit is provided with a temperature sensor for detecting the temperature of the conditioned air cooled by the evaporator, and the detected value of the temperature sensor is used. The proportional control valve is controlled, whereby the conditioned air cooled by the evaporator is precisely temperature controlled.

  In this invention, the refrigerant | coolant piping which connects the refrigerant | coolant exit of the said evaporator and the suction side of a compressor is connected to the suction pressure adjustment valve which hold | maintains the refrigerant | coolant suction pressure of a compressor uniformly, and the said expansion valve is a temperature type expansion valve. And a temperature sensing cylinder of the temperature type expansion valve is provided in a pipe upstream of the suction pressure adjusting valve, whereby the refrigerant evaporation pressure in the evaporator is kept constant.

  In the present invention, a high pressure sensor is provided in a high pressure side refrigerant pipe from the condenser to the temperature type expansion valve, and on the other hand, a variable capacity fan of the heat radiating unit is driven by an inverter device, and the refrigerant detected by the high pressure sensor The rotation of the variable capacity fan is controlled by an inverter device so that the condensing pressure of the refrigerant becomes constant, whereby the refrigerant condensing pressure in the condenser is kept constant.

  A liquid receiving tank may be connected to the high-pressure side refrigerant pipe between the condenser and the high-pressure sensor.

  The casing that houses the heat recovery unit and the heat dissipation unit may be provided in a return chamber of the clean room.

  According to the present invention, when the temperature in the air to be air-conditioned is precisely controlled, the conditioned air is precisely temperature-controlled by flowing hot gas to the evaporator that air-conditions the chamber air, and heat is recovered by the evaporator. A large amount of heat is exhausted by air cooling with a condenser in the heat dissipation section installed in the clean room, enabling stable precise temperature control and eliminating the need for an outdoor unit or cold water source outside the clean room. It exhibits an excellent effect of being able to be made.

1 is an overall view showing an embodiment of the present invention. It is detail drawing of the refrigerating cycle of the precision air conditioning machine shown in FIG. It is explanatory drawing which showed the refrigerating cycle in FIG. 2 on the Mollier diagram.

  A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

  First, a clean room 10 and a precision air conditioner 13 that air-conditions a chamber 12 as an air-conditioning target that covers a process device 11 such as an exposure apparatus installed in the clean room 10 will be described with reference to FIG.

  The clean room 10 is formed above a clean zone 16 in which a process device 11 such as an exposure apparatus is installed and a chamber 12 covering the process device 11 is provided, and a ceiling 17 of the clean zone 16, and supplies clean air to the clean zone 16. An air supply chamber 18 to be aired and a return chamber 20 which is formed under the floor 19 of the clean zone 16 and sucks air from the clean zone 16 are configured. The return chamber 20 and the air supply chamber 18 are connected by a circulation path 21, a clean room air conditioner 22 is provided in the circulation path 21, and clean air is blown out to the clean zone 16 on the ceiling 17 in the air supply chamber 18. A plurality of fan filter units 23 having HEPA and fans are provided. The air from the return chamber 20 is introduced into the air conditioner 22 through the circulation path 21 and air-conditioned to the set temperature by the air conditioner 22, and the air-conditioned air passes from the air supply chamber 18 through the high performance filter in the fan filter unit 23. It is cleaned and blown out to the clean zone 16 in a down flow.

  In the clean zone 16, a chamber 12 that covers the process equipment 11 is installed on the floor 19, and the inside of the chamber 12 is air-conditioned by the precision air conditioner 13, thereby precisely controlling the temperature of the process equipment 11 and the environment surrounding the process equipment 11. It is like that.

  In the present invention, the precision air conditioner 13 is installed in the clean room 10, particularly in the return chamber 20. In other words, the precision air conditioner 13 introduces the air in the chamber 12 as return air (RA), performs precision air conditioning on the air, and supplies and circulates the air to the chamber 12 as a supply air SA. The unit 28 includes a device unit 30 including a compressor 29 and the like, and a heat radiating unit 33 including a condenser 31 and a variable capacity fan 32 for air cooling. Here, the heat radiating section 33 is provided at least in the clean room 10, particularly in the return chamber 20. Further, as shown in the figure, the equipment unit 30 including the heat recovery unit 28, the compressor 29, and the like, and the heat radiating unit 33 are housed in one casing 14 to form the precision air conditioner 13. The precision air conditioner 13 is provided in the clean zone 16 and the return chamber 20 in the clean room 10, and particularly preferably provided in the return chamber 20.

  Next, the refrigeration cycle 25 constituting the precision air conditioner 13 will be described with reference to FIG.

  The refrigeration cycle 25 includes, from the discharge side to the suction side of the compressor 29, the condenser 31 of the heat radiating unit 33, the liquid receiving tank 34, the temperature type expansion valve 35 as an expansion valve, the evaporator 26 of the heat recovery unit 28, and the accumulator 36. Are sequentially connected by a refrigerant pipe 37, and further, a hot gas bypass circuit 40 that branches from a high-pressure side refrigerant pipe 37a from the discharge side of the compressor 29 to the condenser 31 and flows hot gas to the evaporator 26 is provided. Configured.

  This refrigeration cycle 25 will be described in more detail.

  The high pressure side refrigerant pipe 37 a on the discharge side of the compressor 29 is provided with a pressure switch 41 that detects an overload of the compressor 29, and the high pressure side refrigerant pipe 37 a is connected to the inlet side of the condenser 31. A condensing pressure adjusting valve 50 is connected to the high-pressure side refrigerant pipe 37 a on the inlet side of the condenser 31. The condenser 31 is formed of fins and tubes, and the variable capacity fan 32 is provided in the condenser 31 to form a heat radiation portion 33. The high-pressure side refrigerant pipe 37 a on the outlet side of the condenser 31 is connected to the upper part of the liquid receiving tank 34, and the high-pressure side refrigerant pipe 37 b is connected to the bottom of the liquid receiving tank 34. A high-pressure sensor 42 is connected to the high-pressure side refrigerant pipe 37b extending from the liquid receiving tank 34 to the temperature type expansion valve 35. Further, a sight glass 43 for detecting the amount of water is connected to the high-pressure side refrigerant pipe 37b downstream thereof. A filter dryer 44 for removing moisture in the refrigerant and a backless valve 45 as a stop valve are connected.

  A low-pressure side refrigerant pipe 37 c from the temperature type expansion valve 35 is connected to the inlet side of the evaporator 26. The evaporator 26 is formed of fins and tubes, and a circulation fan 27 is provided on the outlet side of the evaporator 26 to form a heat recovery unit 28.

  A pressure gauge 46, an external pressure equalizing introduction valve 47, a strainer 48, and a suction pressure adjusting valve 49 are sequentially connected to a low-pressure side refrigerant pipe 37c extending from the outlet side of the evaporator 26 to the accumulator 36.

  The temperature type expansion valve 35 is formed of a diaphragm valve. Although not shown in detail, the temperature chamber 52 is connected to the temperature sensing cylinder 52 via the capillary tube 51 and the other diaphragm chamber is connected to the outer equalizing tube 53. Is done. The temperature sensing cylinder 52 is provided along the low-pressure side refrigerant pipe 37 c on the outlet side of the evaporator 26, and the outer equalization pipe 53 is connected to the outer equalization introduction valve 47. The temperature type expansion valve 35 has a pressure (pressure based on the evaporation temperature of the evaporator 26) acting on one of the diaphragms from the temperature sensing cylinder 52 through the capillary tube 51, and a pressure acting on the other of the diaphragms from the outer equalizing tube 53. The valve opening degree (decompression degree) is controlled by a differential pressure with respect to (evaporation pressure of the evaporator 26).

  In the illustrated example, the example of the outer-equalization type temperature expansion valve 35 has been described. However, an inner-equalization type temperature expansion valve may be used, or an electric expansion valve may be used.

  The suction pressure adjusting valve 49 receives the downstream refrigerant pressure and adjusts the suction pressure of the compressor 29 so that the refrigerant pressure becomes constant.

  The hot gas bypass circuit 40 includes a bypass pipe 54 connecting the high-pressure side refrigerant pipe 37a extending from the discharge side of the compressor 29 to the condenser 31 and the inlet of the evaporator 26, and a proportional control valve 55 connected to the bypass pipe. Consists of. A strainer 56 is connected to the bypass pipe 54 upstream of the proportional control valve 55.

  The heat recovery unit 28 is provided with a temperature sensor 58 that detects the temperature of the supply air SA that is air-conditioned by the evaporator 26 and is supplied to the chamber 12 by the circulation fan 27. The proportional control valve 55 of the bypass circuit 40 is controlled.

  Further, the variable capacity fan 32 of the heat radiating unit 33 is driven by the inverter device 60 so that the number of rotations can be varied. The inverter device 60 controls the air volume of the variable capacity fan 32.

  In the refrigeration cycle 25 of FIG. 2, the refrigerant gas (hot gas) compressed by the compressor 29 is pressure-controlled by the condensing pressure adjusting valve 50 and mainly passes through the condenser 31, where the capacity variable fan 32 rotates. The heat is exchanged with the air in the return chamber 20 (about 23 to 25 ° C.) that is blown by the air to condense, and the pressure is reduced by the temperature expansion valve 35 and flows to the evaporator 26. On the other hand, a part of the hot gas from the compressor 29 flows from the hot gas bypass circuit 40 to the evaporator 26 together with the gas-liquid mixed phase refrigerant whose flow rate is controlled by the proportional control valve 55 and decompressed by the temperature type expansion valve 35. In the heat recovery unit 28, the return air RA from the chamber 12 is introduced, and this is cooled by the evaporator 26 to a set temperature ± 0.01 to ± 0.1 ° C., and the supply air SA with precise temperature control is used as the chamber 12. To supply.

  The refrigerant heat recovered by the evaporator 26 is adjusted to the suction pressure of the compressor 29 by the suction pressure adjusting valve 49 as the evaporated refrigerant, sucked into the compressor 29 via the accumulator 36 and compressed again to become hot gas. Circulated.

  First, in the present invention, the compressor 29 compresses the evaporative refrigerant, which is adjusted to the suction pressure by the suction pressure adjusting valve 49 and is superheated (temperature higher by 5 ° C. than the saturated gas line), to a predetermined pressure to generate hot gas. And This hot gas is supplied to both the evaporator 26 via the condenser 31 of the heat radiating unit 33 and the hot gas bypass circuit 40. At this time, the pressure on the outlet side of the condenser 31 is detected by the high-pressure sensor 42, and based on this, the inverter device 60 controls the blowing amount of the capacity variable fan 32, and the condensing pressure adjusting valve 50 flows into the condenser 31. Adjust the pressure. Thereby, the heat exchange amount (exhaust heat amount) in the condenser 31 is adjusted, and the condensing pressure in the condenser 31 is kept constant regardless of fluctuations in the hot gas bypass amount. Since the condensation in the condenser 31 exchanges heat with the air in the return chamber 20 (about 23 ° C. to 25 ° C.), the variable temperature fan 32 has a small temperature difference between the condensed refrigerant temperature and the air, and the amount of heat radiation is small. The amount of heat release can be controlled appropriately by the amount of air flow.

  Next, in the precise temperature control of the supply air SA in the heat recovery unit 28, the opening degree of the proportional control valve 55 is controlled by the temperature sensor 58, and the amount of hot gas flowing into the evaporator 26 from the hot gas bypass circuit 40 is controlled. It is done by doing.

  Although the temperature sensor 58 shows an example of detecting the temperature of the supply air SA on the outlet side of the evaporator 26 of the heat recovery unit 28 in the figure, the temperature sensor 58 detects the temperature of the return air RA on the inlet side of the evaporator 26. A temperature sensor may be provided separately, and the proportional control valve 55 may be controlled by the temperature sensor at the entrance / exit.

  On the other hand, the temperature type expansion valve 35 adjusts the degree of pressure reduction to keep the evaporation pressure of the evaporator 26 constant regardless of the hot gas bypass amount. That is, the outlet side temperature of the evaporator 26 is converted into the pressure of the refrigerant sealed in the temperature sensing cylinder 52, and this is introduced into one of the diaphragm chambers of the temperature type expansion valve 35 via the capillary tube 51, and simultaneously evaporated. The evaporation pressure of the refrigerant evaporated in the vessel 26 is introduced to the other of the diaphragm chambers of the temperature type expansion valve 35 through the outer equalizing pipe 53, and the pressure reduction degree of the temperature type expansion valve 35 is adjusted by the differential pressure between the two diaphragm chambers. The

  Thereby, in the evaporator 26, the evaporation pressure is kept constant, and the refrigerant evaporation amount in the evaporator 26, that is, the heat exchange amount between the return air RA and the refrigerant is controlled by the hot gas inflow amount. Precise temperature control according to is performed.

  In the refrigeration cycle 25, the heat recovered by the evaporator 26 of the heat recovery unit 28 is exhausted to the air of the return chamber 20 by the condenser 31 of the heat radiating unit 33. Since the amount of heat processed by the machine 13 is sufficiently small, it can be sufficiently processed by the air conditioning of the air conditioner 13. Therefore, it is not necessary to install an outdoor unit for exhaust heat or a cold water supply device outside the clean room 10 and connect with a refrigerant pipe as in the conventional case.

  Further, when the precise temperature control is performed, in the hot gas bypass circuit 40, the flow rate of the hot gas is controlled by the proportional control valve 55 according to the air conditioning load of the return chamber 20, and flows to the evaporator 26. At this time, the condenser 31 controls the condensing pressure to be constant based on the detection value of the high pressure sensor 42, and at the same time, the temperature type expansion valve 35 controls the evaporating pressure to be constant. The refrigeration cycle 25 is stably operated by adjusting the suction pressure.

  The proportional control valve 55 controls the amount of hot gas according to the air conditioning load fluctuation of the return chamber 20, and the refrigerant recovers heat by the evaporator 26 according to the air conditioning load. Thereafter, the hot gas compressed by the compressor 29 is introduced into the condenser 31 of the heat radiating section 33 and radiated. Since heat is radiated after heat recovery in this manner, when the air conditioning load fluctuates rapidly, the matching between the heat recovery amount and the heat dissipation amount in the refrigeration cycle 25 tends to deteriorate, but the refrigeration cycle 25 includes a liquid receiving tank 34. Therefore, the refrigeration cycle 25 can be stably operated.

  Next, the refrigeration cycle 25 will be described on the Mollier diagram of FIG.

  FIG. 3 shows the refrigeration cycle on the Mollier diagram when R407C is used as the refrigerant, the horizontal axis is the specific enthalpy (kJ / kg), the vertical axis is the absolute pressure (MPa), Lg is the saturated gas line of R407C, Ll indicates a saturated liquid line.

  First, the suction refrigerant of the compressor 29 is introduced into the compressor 29 at a point A (12 ° C., 0.5 MPa) by the suction pressure adjusting valve 49. This point A is in the superheat state on the gas phase side sufficiently higher than the saturated gas line Lg (+ 5 ° C.), and the refrigerant gas is compressed by the compressor 29 to point B (75 ° C., 2.0 MPa). . The hot gas at point B is supplied to the condenser 31 side and the hot gas bypass circuit 40 side, and at that branch point, the pressure is reduced to point C (1.7 MPa). The hot gas introduced into the condenser 31 passes through the saturated liquid line Ll while maintaining the condensation pressure at the point C, and is cooled to the point D (31 ° C.) that becomes the supercooled liquid from the gas-liquid mixed phase state by heat radiation. .

  The degree of supercooling at this point D can be controlled by the temperature type expansion valve 35, and the pressure is reduced to the point E (11 ° C., 0.8 MPa) by the temperature type expansion valve 35. In the evaporator 26, the evaporation pressure is maintained at the pressure at this point E. On the other hand, the hot gas from the point C is introduced into the evaporator 26, whereby the pressure is reduced to the point F (0.8 MPa) and becomes the evaporation pressure of the evaporator 26. The hot gas at point F and the refrigerant depressurized to point E by the temperature type expansion valve 35 flow into the evaporator 26, and the refrigerant exchanges heat with air from the chamber 12 (return air RA). As a result, the refrigerant enters the state of point G and flows from the outlet of the evaporator 26 to the inlet side of the suction pressure adjustment valve 49, and the suction pressure adjustment valve 49 reduces the pressure from point G to point A. It is introduced into the compressor 29.

  In this refrigeration cycle on the Mollier diagram, the amount of heat from point C to point D is the amount of heat released from the condenser 31, and the amount of heat from point E to point G is the change in the amount of heat at the evaporator 26, The amount of heat release is the total amount of heat corresponding to the amount of heat of the compressor 29 (the amount of heat from point G to point F) and the amount of heat of evaporation.

  Here, when the hot gas bypass amount is 0%, the evaporation heat amount of the evaporator 26 is the heat amount from the point E to the point G, and when there is no air conditioning load and the hot gas bypass amount is 100%, the heat amount of the compressor 29. The heat is dissipated by the condenser 26, and the specific enthalpy of the refrigerant at the inlet of the evaporator 26 is a point H obtained by subtracting the amount of heat of the compressor 29 from the point G. Therefore, with respect to the hot gas bypass amount of 0% to 100%, the specific enthalpy of the refrigerant at the inlet of the evaporator 26 is any point H ′ from point E to point H, and the amount of heat from point H ′ to point G is The amount of heat of evaporation according to the air conditioning load, that is, the amount of heat exchanged with the air (return air RA) by the evaporator 26.

  Therefore, by controlling the hot gas bypass amount in the range of 0% to 100% in accordance with the air conditioning load state of the chamber 12, the heat exchange amount according to the air conditioning load between the points E and H shown in the figure can be obtained. Can be adjusted.

  The amount of hot gas bypass that flows to the hot gas bypass circuit 40 can be as much as the amount of heat generated in the compressor can be dissipated when the circulation amount of the refrigerant in the refrigeration cycle 25 is 100%. Even if it flows, the refrigeration cycle 25 can be operated stably. Accordingly, by appropriately performing the flow rate control with the proportional control valve 55, it is possible to precisely control the temperature to ± 0.01 ° C. to ± 0.1 ° C. with respect to the set temperature (for example, 23 ° C.).

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made. That is, although the temperature type expansion valve has been described as an example of the expansion valve, the refrigerant condensation pressure, the evaporation pressure, and the compressor suction pressure when R407 is used as the refrigerant in FIG. Although an example has been shown, it is a matter of course that the compression capacity, the condensation pressure, and the evaporation pressure of the compressor may be changed according to the air conditioning load and the processing air volume.

DESCRIPTION OF SYMBOLS 10 Clean room 12 Chamber 14 Casing 25 Refrigerating cycle 26 Evaporator 28 Heat recovery part 29 Compressor 31 Condenser 32 Capability variable fan 33 Heat radiation part 40 Hot gas bypass circuit

Claims (7)

In a precision air conditioner for introducing air in a chamber to be air-conditioned installed in a clean room and circulating it to the chamber with this set temperature,
A condenser, an expansion valve, and an evaporator are sequentially connected from the discharge side of the compressor to the suction side, and a refrigeration cycle having a hot gas bypass circuit for flowing hot gas on the discharge side of the compressor to the evaporator;
A heat recovery unit that houses the evaporator of the refrigeration cycle, introduces air from the chamber, air-conditions to a set temperature with the evaporator and circulates to the chamber;
A heat dissipating unit provided with a variable capacity fan that is provided in the clean room and accommodates the condenser of the refrigeration cycle, and air-cools the condenser with air in the clean room to keep the condensation pressure of the condenser constant. ,
A precision air conditioner characterized by comprising   The precision air conditioner according to claim 1, wherein the refrigeration cycle, the heat recovery unit, and the heat dissipation unit are accommodated in the same casing.   The hot gas bypass circuit includes a proportional control valve, and the heat recovery unit is provided with a temperature sensor that detects the temperature of the conditioned air cooled by the evaporator, and the proportional value is determined by the detected value of the temperature sensor. The precision air conditioner according to claim 1 or 2, wherein the control valve is controlled, and thereby the conditioned air cooled by the evaporator is precisely temperature controlled.   The refrigerant pipe connecting the refrigerant outlet of the evaporator and the suction side of the compressor is connected to a suction pressure adjusting valve that keeps the refrigerant suction pressure of the compressor constant, and the expansion valve is a temperature type expansion valve, The precision air conditioner according to claim 3, wherein a temperature sensing cylinder of the temperature type expansion valve is provided in a pipe upstream of the suction pressure adjusting valve, whereby the refrigerant evaporation pressure in the evaporator is kept constant.   A high-pressure sensor is provided on the high-pressure side refrigerant pipe from the condenser to the temperature type expansion valve, while the variable capacity fan of the heat radiating unit is driven by an inverter device, and the condensing pressure of the refrigerant detected by the high-pressure sensor is The precision air conditioner according to claim 4, wherein the rotation of the capacity variable fan is controlled by an inverter device so as to be constant, whereby the refrigerant condensing pressure in the condenser is kept constant.   The precision air conditioner according to claim 5, wherein a liquid receiving tank is connected to a high-pressure side refrigerant pipe between the condenser and the high-pressure sensor.   The precision air conditioner according to claim 2, wherein a casing that houses the heat recovery unit and the heat dissipation unit is provided in a return chamber of the clean room.