Cooling device, exposure device, and industrial equipment

Abstract

The present invention comprises: a first refrigeration cycle that includes a compressor (102), a condenser (103), a first decompressor (104a), and a first evaporator (105a), that causes a refrigerant (FL1) to flow into the first evaporator, and that cools an object 1 to be cooled; and a second refrigeration cycle that includes the compressor, the condenser, a second decompressor (104b), a second evaporator (105b), and an evaporation pressure adjustment valve (108a), that causes a refrigerant (FL2) having a flow rate greater than that in the first decompressor to flow into the second evaporator, and that cools an object 2 to be cooled. The driving of the compressor is controlled on the basis of the temperature (116) of the object 2 to be cooled, which has been cooled, the open-close degree of the first decompressor is controlled on the basis of the superheating degree 1 of the refrigerant downstream (118) of the first evaporator, the open-close degree of the second decompressor is controlled on the basis of the superheating degree 2 of the refrigerant downstream (119) of the second evaporator, and the open-close degree of the evaporation pressure adjustment valve is controlled on the basis of the target pressure for the refrigerant on the downstream side (120) of the evaporation pressure adjustment valve or the temperature (117) of the object 1 to be cooled, which has been cooled by the first evaporator.

Description

Cooling equipment, exposure equipment, industrial equipment

[0001] The present invention relates to a cooling device that includes multiple evaporators and is capable of simultaneously cooling multiple objects, and in particular to a cooling device that is suitable for use in industrial equipment that has multiple heat-generating elements with different heat values.

[0002] In recent years, there has been an increase in industrial equipment that has multiple heat-generating elements with different heat output, including semiconductor manufacturing equipment such as exposure machines, laser processing machines, and flat panel display manufacturing equipment. For example, an exposure machine for semiconductor manufacturing contains components such as an optical system including a light source, a motor, a control circuit, and a power supply, which can be considered multiple heat sources with different heat output. To ensure that such industrial equipment operates normally and stably, a cooling device is required that can appropriately cool the multiple heat sources and their surrounding areas according to the amount of heat generated.

[0003] Patent Document 1 describes a refrigerator having three refrigeration cycles. As shown in FIG. 8, the refrigerant flow path downstream of a compressor (1) branches into three flow paths. The first flow path has an expansion valve (4c), an evaporator (5c), and a pressure-reducing valve (8c) connected in series in this order. The second flow path has an expansion valve (4b), an evaporator (5b), and a pressure-reducing valve (8b) connected in series in this order. The third flow path has an expansion valve (4a) and an evaporator (5a) connected in series in this order. The three flow paths merge upstream of the compressor (1), forming three refrigeration cycles. (2) denotes a condenser, (3) denotes a condensed refrigerant tank, (6a) to (6c) denote blower fans, (9) denotes a pressure sensor, and (10) denotes a control device.

[0004] In order to maintain each storage compartment of the refrigerator at a preset temperature, each evaporator adjusts the evaporation temperature of the refrigerant that exchanges heat with the air in the storage compartment. Specifically, based on the measurement value of the temperature sensor installed in each storage compartment, the opening degree of the expansion valve and pressure reducing valve installed in each refrigeration cycle is adjusted so that each evaporator operates at the respective preset evaporation temperature.

[0005] Here, the evaporator (5a) arranged in the third flow path in which no pressure reducing valve is provided has a lower evaporation pressure than the other two evaporators (5b) and (5c). However, even if the evaporation temperatures of the evaporators are different, the evaporation pressures of the evaporators (5b) and (5c) are reduced to match the evaporation pressure of the evaporator (5a) by using the pressure reducing valves (8b) and (8c).

[0006] Japanese Patent Application Laid-Open No. 2004-28354

[0007] However, the refrigeration cycle described in Patent Document 1 does not perform control taking into account the degree of superheat. Therefore, if the expansion valve is opened wider to increase the refrigerant flow rate when the temperature inside the refrigerator rises, refrigerant that did not evaporate in the evaporator may flow into the compressor as a liquid. Furthermore, since the expansion valve opening is changed to adjust the refrigerant flow rate to maintain a constant evaporation temperature, the degree of superheat may vary within a certain range. As a result, the refrigerant's phase state may become unstable, and the refrigerant may flow into the compressor as a liquid, which may cause compressor failure.

[0008] For example, if the temperature inside the refrigerator rises, the compressor speed is increased to increase the refrigerant flow rate in order to improve the cooling capacity of one of the multiple evaporators. In response to this change, the expansion valve aperture is reduced to maintain a constant evaporation temperature. However, reducing the aperture of one refrigeration cycle's expansion valve increases the refrigerant flow rate into the other refrigeration cycles. In the refrigeration cycle with the lowest evaporation pressure, the aperture of the expansion valve located upstream of the evaporator is reduced to maintain a constant evaporation temperature. This reduces the refrigerant flow rate into the evaporator with the lowest evaporation pressure, thereby lowering the evaporation pressure. In response to the drop in evaporation pressure, the aperture of the pressure reducing valves located in the other refrigeration cycles is reduced to maintain the same pressure as the lowest evaporator. As a result, more refrigerant flows into the evaporator with the lowest evaporation pressure, resulting in a shortage of refrigerant flowing to the other refrigeration cycles, further increasing the temperature inside the refrigerator. This further increases the temperature inside the refrigerator, causing the compressor, expansion valve, and pressure reducing valve to repeatedly undergo the aforementioned control, potentially resulting in runaway control.

[0009] Furthermore, in a configuration with multiple refrigeration cycles connected in parallel, as in Patent Document 1, the control equipment for each refrigeration cycle operates based on the temperature detected by a temperature sensor disposed in each storage chamber. Therefore, since the control equipment for each refrigeration cycle operates independently, resonance may occur between the expansion valves or between the expansion valve and the pressure reducing valve, causing an unintended sudden flow of refrigerant into the evaporator, resulting in hunting and an unstable refrigerant flow.

[0010] For example, cooling devices that require precise temperature control of the object being cooled, such as those used in semiconductor exposure equipment, are required to achieve high levels of performance, including fewer malfunctions, high responsiveness to temperature changes, and the ability to suppress hunting and stabilize the flow of refrigerant.

[0011] According to a first aspect of the present invention, there is provided a first refrigeration cycle including a compressor that compresses a refrigerant, a condenser that cools and condenses the refrigerant compressed by the compressor, a first pressure reducer, and a first evaporator, wherein the refrigerant decompressed by the first pressure reducer is made to flow into the first evaporator to cool an object to be cooled; and a second refrigeration cycle including the compressor, the condenser, a second pressure reducer, a second evaporator, and an evaporation pressure regulating valve, wherein the refrigerant is decompressed by the second pressure reducer at a flow rate greater than that of the first pressure reducer and made to flow into the second evaporator to cool an object to be cooled. a second refrigeration cycle for cooling a refrigerant-containing gas, the first refrigeration cycle comprising, as viewed along a refrigerant flow direction, a common flow path in which the compressor and the condenser are connected in this order, and a first flow path in which the first pressure reducer and the first evaporator are connected in this order; and a control unit. The second refrigeration cycle comprises, as viewed along a refrigerant flow direction, the common flow path, and a second flow path in which the second pressure reducer, the second evaporator, and the evaporation pressure regulating valve are connected in this order. the first flow path downstream of the first evaporator and the second flow path downstream of the evaporation pressure control valve join at a joining point and connect to the common flow path upstream of the compressor; the control unit controls the operation of the compressor based on the temperature of the object to be cooled (2) cooled by the second evaporator; obtains a degree of superheat 1 that is the degree of superheat of the refrigerant from the temperature and / or pressure of the refrigerant downstream of the first evaporator in the first flow path and controls the opening / closing degree of the first pressure reducer based on the superheat 1; obtains a degree of superheat 2 that is the degree of superheat of the refrigerant from the temperature and / or pressure of the refrigerant downstream of the second evaporator in the second flow path and controls the opening / closing degree of the second pressure reducer based on the superheat 2; and controls the opening / closing degree of the evaporation pressure control valve based on a target pressure of the refrigerant downstream of the evaporation pressure control valve or the temperature of the object to be cooled (1) cooled by the first evaporator.

[0012] According to a second aspect of the present invention, there is provided a first refrigeration cycle including a compressor that compresses a refrigerant, a condenser that cools and condenses the refrigerant compressed by the compressor, a first pressure reducer, a first evaporator, and an evaporation pressure regulating valve, wherein the refrigerant decompressed by the first pressure reducer is caused to flow into the first evaporator to cool an object to be cooled (1); a second refrigeration cycle including the compressor, the condenser, a second pressure reducer, and a second evaporator, wherein a refrigerant at a flow rate greater than that of the first evaporator is caused to flow into the second evaporator to cool an object to be cooled (2); and a control unit. the first refrigeration cycle comprises, as viewed along the direction of refrigerant flow, a common flow path in which the compressor and the condenser are connected in this order, and a first flow path in which the first pressure reducer, the first evaporator, and the evaporation pressure regulating valve are connected in this order; and the second refrigeration cycle comprises, as viewed along the direction of refrigerant flow, a second flow path in which the common flow path, the second pressure reducer, and the second evaporator are connected in this order, and a flow path branching from the common flow path between the compressor and the condenser and passing through a control valve between the second pressure reducer and the second evaporator. and a hot gas bypass connected to the second flow path at a branch point downstream of the condenser, wherein the common flow path branches into the first flow path and the second flow path at a branch point located downstream of the condenser, the first flow path downstream of the evaporation pressure control valve and the second flow path downstream of the second evaporator join at a joining point and connect to the common flow path upstream of the compressor, and the control unit controls the opening / closing degree of the control valve of the hot gas bypass based on the temperature of the object to be cooled (2) cooled by the second evaporator, obtains a degree of superheat 1 that is the degree of superheat of the refrigerant from a temperature and / or pressure of the refrigerant in the first flow path downstream of the first evaporator and controls the opening / closing degree of the first pressure reducer based on the superheat 1, obtains a degree of superheat 2 that is the degree of superheat of the refrigerant from a temperature and / or pressure of the refrigerant in the second flow path downstream of the second evaporator and controls the opening / closing degree of the second pressure reducer based on the superheat 2, and controls the opening / closing degree of the evaporation pressure control valve based on a target pressure of the refrigerant downstream of the evaporation pressure control valve.

[0013] In cooling devices that precisely control the temperature of a cooling object, such as cooling devices used in semiconductor exposure devices, the present invention can achieve a high level of fewer malfunctions, high responsiveness to temperature changes, and stabilization of the flow of coolant by suppressing hunting. Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings. In the accompanying drawings, the same reference numerals are used to designate the same or similar components.

[0014] 1 is a diagram showing the configuration of a cooling device according to embodiment 1. 2 is a block diagram showing the configuration of a control unit according to embodiment 1. 3 is a diagram showing the configuration of a cooling device according to embodiment 2. 4 is a diagram showing the configuration of a cooling device according to embodiment 3. 5 is a diagram showing the configuration of industrial equipment according to embodiment 4. 6 is a diagram showing the configuration of a cooling device according to embodiment 5. 7 is a table illustrating moving average processing in embodiment 6. 8 is a graph illustrating moving average processing in embodiment 6. 9 is a diagram showing a conventionally known refrigerator.

[0015] First Embodiment (Configuration of Cooling Device) Hereinafter, a cooling device 101 according to a first embodiment of the present invention will be described with reference to the drawings.

[0016] In Fig. 1, the thick lines indicate a refrigerant flow path configured via refrigerant piping 106. The cooling device 101 has two refrigeration cycles (refrigerant circulation paths) arranged in parallel, and the two refrigeration cycles share a compressor 102 and a condenser 103. Note that the refrigeration cycle (refrigerant circulation path) here refers to a cycle in which the refrigerant circulates through "compressor → condenser → pressure reducer (expansion valve) → evaporator" while changing state in order to fulfill the function of the cooling device. Despite the name "refrigeration cycle," it does not necessarily mean that the refrigerant freezes.

[0017] 1 , the flow of refrigerant in each part of the refrigerant flow path is schematically shown by arrows as refrigerant flow FL, refrigerant flow FL1, and refrigerant flow FL2, and the direction of the arrows indicates the direction of refrigerant flow. Refrigerant flow FL flowing through compressor 102 and condenser 103 branches into refrigerant flow FL1 and refrigerant flow FL2 at branch point 115 located downstream of condenser 103. Refrigerant flow FL1 and refrigerant flow FL2 join at junction 112 located upstream of compressor 102 to become refrigerant flow FL, which flows into compressor 102.

[0018] The refrigerant flow FL1 passes through the pressure reducer 104a, the evaporator 105a, and the detector 118 in this order. The compressor 102, the condenser 103, the pressure reducer 104a, and the evaporator 105a constitute a first refrigeration cycle.

[0019] The refrigerant flow FL2 passes through the pressure reducer 104b, the evaporator 105b, the detector 119, the evaporation pressure control valve 108a, and the pressure detector 120 in this order. The compressor 102, the condenser 103, the pressure reducer 104b, the evaporator 105b, and the evaporation pressure control valve 108a constitute a second refrigeration cycle.

[0020] The flow path from the junction 112 through the compressor 102 and the condenser 103 to the branch point is shared by both the first and second refrigeration cycles and can be referred to as a common flow path. In the first refrigeration cycle, the flow path including the pressure reducer 104a (first pressure reducer) and the evaporator 105a (first evaporator) (the flow path from the branch point to the junction point as viewed along the refrigerant flow direction) can be referred to as a first flow path. In the second refrigeration cycle, the flow path including the pressure reducer 104b (second pressure reducer), the evaporator 105b (second evaporator), and the evaporation pressure control valve 108a (the flow path from the branch point to the junction point as viewed along the refrigerant flow direction) can be referred to as a second flow path. Furthermore, the detection unit 118 can be referred to as a first detection means, the detection unit 119 as a second detection means, the pressure detection unit 120 as a third detection means, the temperature detection unit 117 as a first temperature detection unit, and the temperature detection unit 116 as a second temperature detection unit. Furthermore, the object to be cooled 113 can be called the object to be cooled 1, and the object to be cooled 114 can be called the object to be cooled 2.

[0021] In the cooling device 101 according to this embodiment, the evaporator 105a disposed in the first refrigeration cycle and the evaporator 105b disposed in the second refrigeration cycle are used to cool different objects. The evaporator 105b is used to cool an object that requires high-precision temperature control with a high response speed. The evaporator 105a is used to cool an object that can tolerate relatively low-precision temperature control and a relatively low response speed.

[0022] The second refrigeration cycle is configured as a circuit for cooling an object that requires a constant temperature to be maintained with high precision, and is configured to have a greater cooling capacity than the first refrigeration cycle, so that the flow rate of the refrigerant flow FL2 flowing through the second refrigeration cycle is greater than the flow rate of the refrigerant flow FL1 flowing through the first refrigeration cycle.

[0023] For example, when the cooling apparatus 101 according to the embodiment is installed in a semiconductor manufacturing apparatus, the evaporator 105b arranged in the second refrigeration cycle is preferably used as a cooler for maintaining a constant temperature of the atmosphere (e.g., the air circulating through the optical unit and chamber) within the semiconductor manufacturing apparatus. To ensure the accuracy of the optical system of the pattern exposure machine, the atmosphere (air) within the semiconductor manufacturing apparatus must be controlled to, for example, stay within a range of plus or minus 0.01 degrees Celsius around the set temperature. In this embodiment, as described below, the evaporator 105b arranged in the second refrigeration cycle is configured to quickly respond to temperature changes in the air to be cooled. Furthermore, to prevent condensation or freezing due to heat exchange with the air, which could result in the adhesion of moisture or frost and lead to malfunction of the semiconductor manufacturing apparatus, the evaporator 105b is controlled to perform heat exchange at a high evaporation pressure (evaporation temperature).

[0024] Furthermore, the evaporator 105a disposed in the first refrigeration cycle is suitably used as a cooler for cooling a liquid refrigerant (e.g., a fluorine-based inert liquid) for cooling the drive units and light source units that serve as heat sources within the semiconductor manufacturing equipment. The drive units and light source units that serve as heat sources within the semiconductor manufacturing equipment do not need to have their temperatures controlled with as high precision as the air within the equipment; it is sufficient that the liquid refrigerant for cooling the heat sources does not exceed a certain temperature. For this reason, the evaporator 105a is controlled so as to cool the liquid refrigerant so that the temperature does not exceed a certain temperature. Next, the components of the cooling device 101 will be described in order.

[0025] The control unit 200 is a computer for controlling the operation of the cooling device 101. Although the control unit 200 is shown in a distributed arrangement in FIG. 1 , this is merely a schematic illustration of the connection by dotted lines to facilitate understanding of the relationship between the detection means (e.g., sensors) for acquiring information necessary for control and the controlled object, and the control unit 200 does not necessarily have to be physically distributed. The specific form of distribution or integration of the control unit 200 is not limited to the illustrated example, and all or part of it can be functionally or physically distributed or integrated in any unit depending on the usage situation, etc. The control unit 200 can be configured using hardware or software.

[0026] 2 is a simplified block diagram for explaining the connection relationship between the control unit 200 and each element. For convenience of illustration, only the elements necessary for explaining the present invention are shown in FIG. 2, including the control target controlled by the control unit 200 and the detection means for acquiring information necessary for control. The control unit 200 is a computer for controlling the operation of the cooling device 101, and is internally equipped with a CPU, ROM, RAM, I / O ports, etc.

[0027] The ROM stores a basic operation program for the cooling device 101. The ROM also stores a control program for controlling the operation of controlled objects (e.g., the compressor 102, the pressure reducer 104a, the pressure reducer 104b, and the evaporation pressure control valve 108a) based on information input from detection means (e.g., the detection unit 118, the detection unit 119, the pressure detection unit 120, the temperature detection unit 116, and the temperature detection unit 117) provided in various locations. However, these programs may be loaded into the RAM from an external source via a network, or may be loaded into the RAM via a computer-readable recording medium. Specific examples of recording media that can be used include a flexible disk, an optical disk, a magneto-optical disk, a magnetic tape, a USB memory, and an SSD.

[0028] The I / O port of the control unit 200 is connected to an external device 19 such as an external computer and a network. The control unit 200 can input and output data necessary for controlling cooling, such as the heat generation amount and allowable temperature range of each part of the industrial equipment to be cooled by the cooling device 101, between the external computer and the control unit 200 via the I / O port.

[0029] An operation unit 300 and a display unit 301 are connected to the control unit 200 as UI devices (user interface devices). The operation unit 300 can be configured by a terminal such as a handy terminal, or devices such as a keyboard, a jog dial, a mouse, a pointing device, or a voice input device (or a control terminal equipped with these). The display unit 301 can be any device that can display information related to the various processes executed by the control unit 200 on a display screen, and can be, for example, a liquid crystal display device or an organic EL device.

[0030] When creating, editing, or checking programs or parameters (e.g., proportional constants of PID control) for performing the PID control described below, the user can input programs or data from the operation unit 300 or display the programs or data on the display unit 301.

[0031] The compressor 102 draws in and compresses the refrigerant used in the cooling device 101, converting it into a high-temperature, high-pressure gaseous state, and discharges it downstream. Although not shown, a gas-liquid separator may be provided upstream of the suction port of the compressor 102. In this embodiment, an inverter-controlled compressor is preferably used as the compressor 102. This is because an inverter-controlled compressor can change the refrigerant discharge rate with high response by controlling the rotation speed with an inverter. In this case, when performing PID control (described later), the control unit 200 sends a command to the compressor 102 to control the inverter frequency, thereby controlling the refrigerant discharge rate from the compressor 102. This effectively ensures high control response for the compressor 102.

[0032] The condenser 103 flows a cooling liquid between F-F' and cools and condenses the superheated vapor discharged from the compressor 102. The liquefied refrigerant condensed in the condenser 103 flows into the branch point 115 through the refrigerant pipe 106. Although not shown, a receiver may be disposed between the condenser 103 and the branch point 115.

[0033] The pressure reducer 104a, located downstream of the branch point 115 in the first refrigeration cycle, and the pressure reducer 104b, located in the second refrigeration cycle, reduce the pressure of the high-pressure liquefied refrigerant condensed in the condenser 103 to a low-temperature, low-pressure gas-liquid mixed state (a two-phase gas-liquid state). In this embodiment, electronically controlled expansion valves are used for the pressure reducers 4a and 4b. Electronically controlled expansion valves have a wider controllable opening range and a faster response time than mechanically controlled expansion valves. For this reason, electronically controlled expansion valves are particularly suitable for systems in which the refrigerant flow rate throughout the entire refrigeration cycle varies significantly with changes in the rotation speed of the compressor 102, as in this embodiment. When performing PID control (described later), the control unit 200 sends commands to the pressure reducers 4a and 4b to independently control their opening and closing.

[0034] In the first refrigeration cycle, the evaporator 105a, located downstream of the pressure reducer 104a, cools the liquid (object to be cooled) that flows in from the pipe E and flows out to E' using the refrigerant that flows in from the pressure reducer 104a. As mentioned above, a specific example of the liquid (object to be cooled) is a liquid (e.g., a fluorine-based inert liquid) used to cool the drive unit and light source, which are heat sources within the semiconductor manufacturing equipment. In this way, the evaporator 105a uses a decompressed gas-liquid mixed refrigerant to remove heat from the high-temperature object to be cooled that flows in from the pipe E, and then the cooled object to be cooled flows out to E'. When removing heat from the object to be cooled, the refrigerant evaporates and turns into a high-temperature, low-pressure gas, which then returns to the compressor 102 via the junction 112.

[0035] The detection unit 118, which is located downstream of the evaporator 105a in the first refrigeration cycle, is equipped with a temperature sensor that detects the temperature of the refrigerant flowing out of the evaporator 105a, a pressure sensor that detects the pressure, and a transmission unit that transmits the temperature and pressure detection results to the control unit 200.

[0036] In the second refrigeration cycle, evaporator 105b, located downstream of pressure reducer 104b, cools air flowing in as object 114 to be cooled using the refrigerant flowing in from pressure reducer 104b. A specific example of object 114 to be cooled is the atmosphere inside a semiconductor manufacturing device (e.g., the air circulating through an optical unit and a chamber). In this way, evaporator 105b uses a reduced-pressure gas-liquid mixture of refrigerant to remove heat from and cool high-temperature object 114. When removing heat from the object to be cooled, the refrigerant evaporates and turns into saturated vapor, which then returns to compressor 102 via junction 112.

[0037] In the second refrigeration cycle, to prevent condensation on surrounding equipment when the refrigerant passes through the evaporator 105b and exchanges heat with the object to be cooled 114, the evaporator 105b must exchange heat under conditions similar to the ambient temperature of the cooling device 101. For this reason, the evaporator 105b is configured to exchange heat with the object to be cooled 114 at a higher evaporation pressure than the evaporator 105a of the first refrigeration cycle. This configuration increases the difference in pressure between the outlets of the evaporators 105a and 105b, potentially causing the refrigerant flows to merge unstably at the junction 112. Unstable refrigerant flow can reduce heat exchange controllability, resulting in fluctuations in the temperature of the object to be cooled and, in some cases, making it impossible to achieve the required cooling capacity. Unstable refrigerant flow is particularly undesirable in cooling devices that cool devices requiring high-precision temperature control, such as semiconductor manufacturing equipment.

[0038] Therefore, in this embodiment, the evaporation pressure control valve 108a is disposed in the second refrigeration cycle downstream of the evaporator 105b and upstream of the junction 112, as viewed along the refrigerant flow FL2. It is preferable to use an electronically controlled expansion valve as the evaporation pressure control valve 108a, and the control unit 200 controls the opening of the evaporation pressure control valve 108a to reduce the pressure of the refrigerant flowing out of the evaporator 105b to the same pressure as the refrigerant flowing out of the evaporator 105a. This reduces the pressure difference between the refrigerant flows FL2 and FL1 at the junction 112, improving the controllability and stability of the cooling operation.

[0039] In this embodiment, temperature detection unit 116, which detects the temperature of cooled object 114 cooled by evaporator 105b, is disposed downstream of evaporator 105b in the direction of flow of cooled object 114. Temperature detection unit 116 includes a temperature sensor that detects the temperature of cooled object 114 and a transmission unit that transmits the detection result to control unit 200.

[0040] In the second refrigeration cycle, a detection unit 119 is disposed downstream of the evaporator 105b to detect the temperature and pressure of the refrigerant flowing out from the evaporator 105b. The detection unit 119 includes a temperature sensor, a pressure sensor, and a transmission unit that transmits the detected temperature and pressure results to the control unit 200.

[0041] (Operation of Cooling Device) Next, the operation of cooling device 101 will be described. Control unit 200 controls the operation of compressor 102 based on the temperature of cooled object 114 detected by temperature detection unit 116, i.e., the temperature of cooled object 114 cooled by evaporator 105b in the second refrigeration cycle. Specifically, control unit 200 controls the amount of refrigerant discharged from compressor 102 by changing the rotation speed (number of rotations per unit time) of compressor 102 based on the detection result of temperature detection unit 116.

[0042] When the temperature of the object to be cooled 114 rises above a preset temperature, the rotation speed of the compressor 102 is increased, and control is performed to increase the flow rate of the refrigerant flowing through the entire circuit. Increasing the flow rate of the refrigerant increases the heat exchange per unit time, promoting the removal of more heat from the object to be cooled 114. Furthermore, when the temperature of the object to be cooled falls below a preset temperature, control is performed to decrease the rotation speed of the compressor 102, and reduce the flow rate of the refrigerant flowing through the entire circuit. Reducing the flow rate of the refrigerant suppresses the heat exchange per unit time, preventing the object to be cooled 114 from being cooled more than necessary.

[0043] The control unit 200 controls the aperture of the pressure reducer 104a based on the degree of superheat (superheat degree 1) of the refrigerant flowing out of the evaporator 105a. The degree of superheat of the refrigerant flowing out of the evaporator 105a is calculated based on the temperature or pressure of the refrigerant detected by the detection unit 118 located downstream of the evaporator 105a. If the calculated degree of superheat is greater than a preset degree of superheat, the control unit 200 increases the aperture of the pressure reducer 104a to increase the flow rate of refrigerant flowing into the evaporator 105a in order to suppress the degree of superheat. On the other hand, if the degree of superheat is less than the preset degree of superheat, the control unit 200 reduces the aperture of the pressure reducer 104a to decrease the flow rate of refrigerant flowing into the evaporator 105a in order to ensure that the refrigerant flowing out of the evaporator is vaporized and prevent liquid return to the compressor.

[0044] The control unit 200 controls the aperture of the pressure reducer 104b based on the superheat degree (superheat degree 2) of the refrigerant flowing out of the evaporator 105b. The superheat degree of the refrigerant flowing out of the evaporator 105b is calculated based on the refrigerant temperature or pressure detected by a detection unit 119 located downstream of the evaporator 105b. If the calculated superheat degree is greater than a preset superheat degree, the control unit 200 increases the aperture of the pressure reducer 104b to increase the flow rate of refrigerant flowing into the evaporator 105b in order to suppress the superheat degree. On the other hand, if the superheat degree is less than the preset superheat degree, the control unit 200 decreases the aperture of the pressure reducer 104b to reduce the flow rate of refrigerant flowing into the evaporator 105b, because it is necessary to reliably vaporize the refrigerant flowing out of the evaporator and prevent liquid return to the compressor.

[0045] When the control unit 200 obtains the degree of superheat of the refrigerant, it may obtain the degree of superheat by calculation using the detected temperature or pressure of the refrigerant, or it may obtain the degree of superheat by storing the correspondence between the detected value and the degree of superheat in advance as a lookup table and referring to the lookup table.

[0046] As described above, the control unit 200 controls the first refrigeration cycle so that the degree of superheat of the refrigerant flowing out of the evaporator 105a becomes a preset value. At this time, the control unit 200 controls the evaporation pressure regulating valve 108a of the second refrigeration cycle so that the pressure of the refrigerant on the outlet side of the evaporator 105a, which has been controlled to the preset degree of superheat, becomes equal to the pressure detected by the pressure detecting unit 120 of the second refrigeration cycle.

[0047] In other words, the pressure of the refrigerant flowing out of the evaporator 105a is set as the outlet pressure (target pressure) of the evaporation pressure regulating valve 108a so that the degree of superheat becomes a predetermined value, and the opening degree of the evaporation pressure regulating valve 108a is controlled. Specifically, the set target pressure is compared with the pressure detected by the pressure detection unit 120, and the opening and closing of the evaporation pressure regulating valve 108a is controlled so that these values ​​become equal. This control adjusts the pressure of the refrigerant flowing out of the evaporation pressure regulating valve 108a to a value similar to the pressure of the refrigerant flowing out of the evaporator 105a, thereby stabilizing the merging of the refrigerants at the junction 112. Note that the evaporation pressure regulating valve 108a may be feedback-controlled so that the pressure detected by the detection unit 118 and the pressure detected by the pressure detection unit 120 become equal.

[0048] Furthermore, instead of using the pressure detection unit 120 disposed downstream of the evaporation pressure control valve 108a for control, the opening degree of the evaporation pressure control valve 108a may be controlled using a temperature detection unit 117 that detects the temperature of the object to be cooled 113 after heat exchange by the evaporator 105a. This is because, as will be described below, there is a correlation between the temperature detected by the temperature detection unit 117 and the pressure of the refrigerant adjusted by the evaporation pressure control valve 108a.

[0049] For example, increasing the aperture of the evaporation pressure control valve 108a reduces the pressure loss caused by the evaporation pressure control valve 108a and simultaneously reduces the amount of refrigerant flowing into the evaporator 105a, resulting in an increase in the temperature of the cooled object 113 detected by the temperature detection unit 117. On the other hand, decreasing the aperture of the evaporation pressure control valve 108a increases the pressure loss caused by the evaporation pressure control valve 108a and simultaneously increases the amount of refrigerant flowing into the evaporator 105a, resulting in a decrease in the temperature of the cooled object 113 detected by the temperature detection unit 117. In this way, the aperture of the evaporation pressure control valve 108a changes the pressure loss caused by the evaporation pressure control valve 108a and the amount of refrigerant flowing into the evaporator 105a. Therefore, the aperture of the evaporation pressure control valve 108a can adjust the pressure downstream of the evaporation pressure control valve 108a and the temperature of the cooled object 113 detected by the temperature detection unit 117. In other words, if the evaporation pressure regulating valve 108a is controlled so that the temperature detected by the temperature detection unit 117 becomes a preset temperature, the pressure downstream of the evaporation pressure regulating valve 108a will become a pressure corresponding to the temperature detected by the temperature detection unit 117.

[0050] In order to stabilize the flow of refrigerant flowing into the junction 112 by bringing the pressure of the refrigerant flowing out of the evaporator 105a and the pressure of the refrigerant reduced by the evaporation pressure control valve 108a close to each other, the above-mentioned correlation can be utilized to control the evaporation pressure control valve 108a based on the temperature detected by the temperature detection unit 117.

[0051] In other words, since the pressure of the refrigerant flowing out from the evaporator 105a is determined by presetting the degree of superheat of the refrigerant flowing out from the evaporator 105a, the target value (target temperature) of the temperature detected by the temperature detection unit 117 is set so that this pressure is equal to the pressure downstream of the evaporation pressure control valve 108a.

[0052] The control unit 200 then controls the aperture of the evaporation pressure control valve 108a so that the temperature detected by the temperature detection unit 117 becomes the target temperature. This control makes the pressure downstream of the evaporator 105a and the pressure downstream of the evaporation pressure control valve 108a approximately equal, stabilizing the merging at the junction 112. Note that installing the temperature detection unit 117 and adjusting the aperture of the evaporation pressure control valve 108a not only contributes to stabilizing the merging at the junction 112, but also changes the cooling capacity of the evaporator 105a to maintain a constant temperature of the object 113 to be cooled. As a result, it is no longer necessary to install a temperature control device such as a heater on the inlet or outlet side of the object to be cooled in the evaporator 105a to adjust the temperature of the object, which can contribute to cost reduction, device miniaturization, and energy conservation.

[0053] In this embodiment, the operations of the compressor 102, the pressure reducer 104a, the pressure reducer 104b, and the evaporation pressure regulating valve 108a are controlled using PID control.

[0054] When the control unit 200 performs PID control on the operation (rotation speed S1) of the compressor 102, the following equation 1 is used. where S1 is the rotation speed of the compressor 102, and ΔP1 is the deviation between the target temperature of the object 114 (for example, air) cooled by the evaporator 105b and the temperature detected by the temperature detection unit 116.

[0055] When the control unit 200 performs PID control on the operation (opening degree S2) of the pressure reducer 104b, the following equation 2 is used. where S2 is the opening degree of the pressure reducer 104b, and ΔP2 is the deviation between the superheat degree of the refrigerant calculated based on the detection result of the detection unit 119 and the set superheat degree.

[0056] When the control unit 200 performs PID control on the operation (opening degree S3) of the pressure reducer 104a, the following equation 3 is used. where S3 is the opening degree of the pressure reducer 104a, and ΔP3 is the deviation between the superheat degree of the refrigerant calculated based on the detection result of the detection unit 118 and the set superheat degree.

[0057] When the control unit 200 performs PID control on the operation (opening degree S4) of the evaporation pressure regulating valve 108a, the following equation 4 is used. where S4 is the opening degree of the evaporation pressure regulating valve 108a, and ΔP4 is the deviation between the detection result of the pressure detection unit 120 and the target pressure. Note that ΔP4 may also be the deviation between the target temperature of the object to be cooled 113 and the detection result of the temperature detection unit 117.

[0058] The proportional control constants K of the compressor 102, the pressure reducer 104b, the pressure reducer 104a, and the evaporation pressure regulating valve 108a in the above formulas 1 to 4 are ｐ１ , K. ｐ２ , K. ｐ３ , K. ｐ４ are set to satisfy the relationship of the following formula 5.

[0059] (Equation 5) K ｐ１ >K ｐ２ >K ｐ３ >K ｐ４

[0060] By setting the control response speeds RS1 of the compressor 102 in this manner, it is possible to make the control response speed RS1 of the compressor 102 faster than the control response speeds RS2 of the pressure reducer 104b, RS3 of the pressure reducer 104a, and RS4 of the evaporation pressure control valve 108a. Furthermore, it is possible to make the control response speed RS2 of the pressure reducer 104b slower than the control response speed RS1 of the compressor 102 and faster than the control response speeds RS3 of the pressure reducer 104a and RS4 of the evaporation pressure control valve 8a. Furthermore, it is possible to make the control response speed RS3 of the pressure reducer 104a slower than the control response speeds RS1 of the compressor 102 and RS2 of the pressure reducer 4b, and faster than the control response speed RS4 of the evaporation pressure control valve 8a. Furthermore, it is possible to make the control response speed RS4 of the evaporation pressure control valve 108a slower than the control response speeds RS1 of the compressor 102, RS2 of the pressure reducer 104b, and RS3 of the pressure reducer 104a.

[0061] In this embodiment, by making it possible to control the compressor 102 at the fastest speed, the cooling capacity of the evaporator 105b can be precisely controlled in accordance with changes in the temperature of the object to be cooled 114 (e.g., air), and therefore it is possible to precisely control the temperature of the object to be cooled 114 to fall within a range of plus or minus 0.1 degrees around the target temperature, for example.

[0062] Since the pressure reducer 104b is disposed upstream of the evaporator 105b, which requires a larger cooling capacity than the evaporator 105a, the pressure reducer 104b needs to allow a larger amount of refrigerant to flow into the evaporator 105b than the amount of refrigerant that the pressure reducer 104a allows to flow into the evaporator 105a. Therefore, the second refrigeration cycle is more likely than the first refrigeration cycle to return the refrigerant to the compressor 102 in a gas-liquid two-phase state.

[0063] Therefore, in order to stabilize the degree of superheat of the refrigerant downstream of the evaporator 105b at a preset value, it is necessary to control the opening of the pressure reducer 104b so that it quickly follows the state of the refrigerant flowing out of the evaporator 105b. If the control response speed of the pressure reducer 104a is made faster than that of the pressure reducer 104b, the opening of the pressure reducer 104b, which has a slower control response speed, will change even while the opening of the pressure reducer 104a is attempting to converge to a certain opening. When the opening of the pressure reducer 104b changes in this way, the amount of refrigerant flowing into the evaporator 105a also changes, causing further fluctuations in the degree of superheat, which may prevent the control of the pressure reducer 104a from converging and cause hunting.

[0064] On the other hand, if the control response speed of the pressure reducer 104b is made faster than that of the pressure reducer 104a, even if the opening of the pressure reducer 104a changes while the opening of the pressure reducer 104b is converging to a certain opening, the change in the amount of refrigerant flowing into the pressure reducer 104b caused by the change in the pressure reducer 104a will not be large enough to cause a large change in the degree of superheat. Therefore, divergence of the control of the pressure reducer 104b is unlikely to occur.

[0065] Proportional constant K of pressure reducer 104b ｐ２ can be set small enough to maintain a constant degree of superheat in the evaporator 105b. The pressure reducer 104a is disposed upstream of the evaporator 105a, which does not require precise temperature adjustment compared to the evaporator 105b, and therefore does not need to have a control response speed faster than that of the pressure reducer 104b.

[0066] The opening of the evaporation pressure control valve 108a is controlled based on the pressure downstream of the evaporation pressure control valve 108a detected by the pressure detection unit 120 or the temperature of the cooled object 113 after cooling detected by the temperature detection unit 117. Therefore, if the evaporation pressure control valve 108a is controlled with a faster control response speed than the pressure reducer 104a located upstream of the evaporator 105a, the upstream pressure reducer 104a may not be able to follow changes in the refrigerant flow rate associated with changes in the opening of the evaporation pressure control valve 108a and may not be able to maintain a preset degree of superheat. Similarly, if the evaporation pressure control valve 108a is controlled with a faster control response speed than the pressure reducer 104b located upstream of the evaporator 105b, it may not be able to follow changes in the refrigerant flow rate associated with changes in the opening of the evaporation pressure control valve 108a and may not be able to maintain a preset degree of superheat. Furthermore, since the evaporation pressure control valve 108a has the slowest control response speed among all the control devices, it is possible to adjust the opening degree in response to low-frequency pressure disturbances remaining in the refrigerant that has passed through the evaporator 105b, thereby further stabilizing the state of the refrigerant.

[0067] As described above, by setting the control response speed when PID controlling each control device so that it becomes faster from the upstream side and in order of increasing refrigerant flow rate, hunting can be prevented, the refrigerant flow can be stabilized, and precise temperature control is possible. Note that, although the control response speed of each control device is adjusted by the proportional constant of PID control in this embodiment, other means may be used as long as it can set the control response speed of each control device in the above-mentioned order.

[0068] In addition, in (Equation 1) to (Equation 4), K ｉ１ ~K ｉ４ , K. ｄ１ ~K ｄ４ The control response speed of the controlled object may be changed by changing any of the values ​​of K ｉ１ ~K ｉ４ , K. ｄ１ ~K ｄ４ can be determined by a technique called the transient response method in order to stabilize the control.

[0069] [Embodiment 2] A cooling device 121 according to Embodiment 2 of the present invention will be described with reference to Figure 3. Descriptions of matters common to Embodiment 1 will be simplified or omitted. The cooling device 121 of Embodiment 2 shown in Figure 3 includes a third refrigeration cycle branching off from a branch point 115 in addition to the first and second refrigeration cycles of Embodiment 1. That is, a pressure reducer 104c (third pressure reducer), an evaporator 105c (third evaporator), and an evaporation pressure control valve 108b (second evaporation pressure control valve) are connected in series via a refrigerant pipe 106 from the branch point 115 toward a junction 112. A refrigerant flow FL3 flowing through this flow path and a refrigerant flow FL flowing through a compressor 102 and a condenser 103 constitute the third refrigeration cycle.

[0070] In this embodiment, the control unit 200 fixes the opening degree of the pressure reducer 104c so that the evaporation pressure of the evaporator 105c is greater than that of the evaporator 105a but less than that of the evaporator 105b. If the evaporation pressure of the evaporator 105c is controlled to vary, a significant change in the temperature of the cooled object 125 (cooled object 3) could result in the evaporation pressure of the evaporator 105c being greater than that of the evaporator 105b or less than that of the evaporator 105a. That is, the amount of refrigerant flowing into the evaporator 105c could be the greatest or the least. In this case, the order of the control response speeds of the devices would need to be changed, potentially complicating the control process. To avoid this, the evaporation pressure of the evaporator 105c is fixed in this embodiment. At this time, by setting the opening degree of the pressure reducer 104c so that the refrigerant flowing out from the evaporator 105c has a certain degree of superheat, it is possible to prevent the liquid from returning to the compressor 102. In this example, an electronically controlled valve is used as the pressure reducer 104c, and the pressure reducer 104c is fixed to a predetermined opening degree under the control of the control unit 200, but a mechanical valve whose opening degree is adjusted and fixed in advance may also be used.

[0071] The control unit 200 also adjusts the aperture of the evaporation pressure control valve 108b based on the temperature of the cooled object 125 detected by the temperature detection unit 126 and the refrigerant pressure downstream of the evaporation pressure control valve 108b detected by the pressure detection unit 127, so as to maintain the evaporation pressure at a preset constant value. The control response speed for adjusting the aperture of the evaporation pressure control valve 108b is set to increase from the upstream side and in order of increasing refrigerant flow rate, as described in the first embodiment. This suppresses hunting and stabilizes the refrigerant flow, enabling precise temperature adjustment of the cooled object 114 cooled by the evaporator 105b. The evaporation pressure control valve 108b only needs to maintain the evaporation pressure of the evaporator 105c constant, so the aperture of the evaporation pressure control valve 108b may be controlled based solely on the measurement results of the temperature detection unit 126 or solely on the measurement results of the pressure detection unit 127.

[0072] [Embodiment 3] A cooling device 128 according to Embodiment 3 of the present invention will be described with reference to Figure 4. Descriptions of matters common to Embodiments 1 and 2 will be simplified or omitted. The cooling device 128 of Embodiment 3 shown in Figure 4 includes a fourth refrigeration cycle branching from branch point 115 in addition to the first, second, and third refrigeration cycles of Embodiment 2. That is, a pressure reducer 104d, an evaporator 105d, and an evaporation pressure control valve 108d are connected in series via refrigerant piping 106 from branch point 115 toward junction 112. A refrigerant flow FL4 flowing through this flow path and a refrigerant flow FL flowing through the compressor 102 and the condenser 103 constitute the fourth refrigeration cycle.

[0073] Regarding the fourth refrigeration cycle, if the evaporation pressure of evaporator 105d is set to be greater than the evaporation pressure of evaporator 105a and less than the evaporation pressure of evaporator 105b, it can be controlled in the same manner as the third refrigeration cycle.

[0074] By increasing the control response speed of the device from the upstream side and in order of increasing refrigerant flow rate, hunting is suppressed and the flow of refrigerant is stabilized, making it possible to precisely adjust the temperature of the object to be cooled in the second refrigeration cycle, for example, within a range of plus or minus 0.1 degrees of the set temperature.

[0075] [Fourth Embodiment] A fourth embodiment in which the cooling device 121 according to the second embodiment is incorporated into industrial equipment to cool various parts of the industrial equipment will be described with reference to Fig. 5. Fig. 5 is a schematic block diagram showing an example in which the cooling device 121 according to the second embodiment is incorporated into an exposure apparatus 20 that exposes a fine pattern for semiconductor manufacturing onto a semiconductor substrate.

[0076] A control circuit system 21, a drive power system 22, an optical unit 23, etc. are arranged inside a chamber 28 of the exposure apparatus 20. The control circuit system 21 includes, for example, a power supply and a computer, the drive power system 22 includes, for example, a stage drive motor, and the optical unit 23 includes, for example, a light source and a lens drive motor. In other words, each of these components is a heat source, and in an exposure apparatus 20 that requires precise mechanical accuracy, it is important to control the temperature of not only these components but also the atmosphere 24 inside the chamber.

[0077] Of these, the control circuit system 21 and the drive power system 22 generate relatively little heat and the time fluctuation of the heat generation amount is also small, so they are cooled with a substantially constant cooling capacity using the evaporators 105a and 105c of the cooling device 121. Specifically, the control circuit system 21 and the drive power system 22 are provided with a liquid-cooling mechanism, and the coolant is circulated using pumps 25 and 26.

[0078] In contrast, the area around the optical unit 23 generates a relatively large amount of heat, and this heat is diffused into the atmosphere inside the chamber. Temperature fluctuations in the optical unit 23 have a significant impact on the exposure accuracy of fine patterns, so the optical unit 23 and the atmosphere inside the chamber must have a sufficiently large cooling capacity and must be precisely controlled to suppress temperature fluctuations. For this reason, in this embodiment, a mechanism is provided to air-cool the optical unit 23 and the chamber, and a blower 27 is used to send the air around the optical unit 23 and the atmosphere inside the chamber to an evaporator 105b, which has a large cooling capacity, where it is cooled and circulated.

[0079] The operation of the cooling device 121 in the example of Fig. 5 will be described again with reference to Fig. 3. First, to ensure stable operation of the compressor 102, it is necessary to draw in a refrigerant at a temperature of 35°C or less and a pressure of 0.2 MPa or more and 1.2 MPa or less. However, as will be described later, the refrigerant flow FL2 returning from the evaporator 105b to the junction 112 has a pressure of 1.0 MPa and a temperature of about 24°C, so this is not a problem. The refrigerant drawn into the compressor 102 is compressed to a pressure of 2.25 MPa and sent to the condenser 103 as a gas at a temperature of about 65°C.

[0080] The refrigerant that has entered the condenser 103 is cooled by heat exchange with the cooling liquid flowing between F and F', and is sent to the branch point 115 as a liquid with a pressure of 2.25 MPa and a temperature of 25°C.

[0081] In the pressure reducer 104b, the opening and closing degree of the expansion valve is controlled by the control unit 200 as described above. The state of the refrigerant flowing out from the pressure reducer 104b toward the evaporator 105b changes depending on the opening and closing degree of the expansion valve, but is generally in a gas-liquid two-phase (mixed) state in which liquid and gas coexist, with a pressure of 1.0 MPa and a temperature of approximately 14°C.

[0082] The evaporator 105a exerts a cooling capacity of 2000 W and cools the coolant in the control circuit system 21 of the exposure apparatus 20 from 25° C. to 21° C. In the pressure reducer 104a, the opening and closing degree of the expansion valve is controlled by the control unit 200 as described above. At the outlet of the evaporator 105a, the refrigerant becomes a gas with a pressure of approximately 0.9 MPa and a temperature of approximately 21° C., and flows into the junction 112.

[0083] The evaporator 105c exerts a cooling capacity of 4000 W and cools the coolant in the drive power system 22 of the exposure apparatus 20 from 25° C. to 20° C. In the pressure reducer 104c, the opening and closing degree of the expansion valve is controlled by the control unit 200 as described above.

[0084] Although this varies depending on the opening and closing degree of the pressure reducer 4, the refrigerant becomes a gas state with a pressure of approximately 0.95 MPa and a temperature of approximately 22° C. at the outlet of the evaporator 105c and flows into the junction 112.

[0085] The evaporator 105b exerts a maximum cooling capacity of 6000 W and cools the cooling air of the optical unit 23 of the exposure tool 20 and the atmosphere (air) within the chamber from approximately 25°C to 23°C. The temperature of the air before cooling fluctuates around 25°C depending on the operating state of the exposure tool 20. However, in order to control the temperature after cooling to 23°C, the cooling capacity of the evaporator 105b is not always fixed at a constant 6000 W but is adjusted appropriately. That is, the control unit 200 detects the temperature of the air, which is the object to be cooled 114, that has passed through the evaporator 105b using the temperature detection unit 116, controls the rotation speed of the compressor 102, and adjusts the amount of refrigerant flowing through the evaporator 105b so that the air temperature reaches 23°C. The refrigerant that has passed through the evaporator 105b is vaporized at a superheat degree of 10°C at the evaporator outlet, so the refrigerant temperature reaches 24°C and is returned to the junction 112.

[0086] The cooling device of this embodiment, which arranges in parallel a refrigeration cycle including an evaporator that requires the greatest cooling capacity and also requires highly accurate temperature control, and a refrigeration cycle including an evaporator that requires a relatively small cooling capacity and also allows relatively low accuracy temperature control, and performs the control described above, is highly useful and can be suitably used in various industrial equipment including exposure machines. Note that the values ​​of pressure, temperature, cooling capacity, etc. given above are merely examples, and it goes without saying that this embodiment is not limited to these examples.

[0087] [Embodiment 5] A cooling device 130 according to embodiment 5 of the present invention will be described with reference to Figure 6. Descriptions of matters common to embodiment 1 will be simplified or omitted. Embodiment 5 differs from embodiment 1 in the following configuration. A branch point 501 is provided between the compressor 102 and the condenser 103, and a junction point 502 is provided between the pressure reducer 104b and the evaporator 105b, and a hot gas bypass connects the branch point 501 and the junction point 502. A control valve 503 controllable by the control unit 200 is provided in the refrigerant pipe 106 of the hot gas bypass to control the flow of hot gas.

[0088] The rotation speed of the compressor 102 is not controlled but is set to a constant value, while the aperture of a control valve 503 provided in the hot gas bypass path is controlled to change depending on the temperature detected by the temperature detection unit 116. In the first embodiment, the refrigerant flow rate flowing into the evaporator 105b is controlled by changing the discharge rate of the compressor 102. In this embodiment, however, the refrigerant flow rate flowing into the evaporator 105b is controlled by changing the mixture ratio of the high-temperature, high-pressure refrigerant flowing in via the hot gas bypass. In this case, in order to precisely control the temperature of the air to be cooled 114, by using S1 in Equation 1 as the aperture of the control valve 503 and applying PID control using Equation 1 to the control valve 503, the same effect as in the first embodiment can be obtained.

[0089] Furthermore, if the configuration allows the cooling capacity of the evaporator 105b to be changed, PID control may be applied to a control method other than control using a hot gas bypass as in this embodiment or control that changes the compressor rotation speed as in embodiment 1.

[0090] Furthermore, while in the first embodiment, the evaporation pressure control valve 108a is located downstream of the evaporator 105b, in this embodiment, the evaporation pressure control valve 108e is located downstream of the evaporator 105a. This is because a pressure loss occurs at the confluence point 502 where the refrigerant that has passed through the hot gas bypass and the low-temperature, low-pressure, gas-liquid two-phase refrigerant that has flowed out of the pressure reducer 104b converge, causing the refrigerant flowing through FL1 to have a higher pressure than the refrigerant flowing through FL2. Therefore, the evaporation pressure control valve 108e is located downstream of the evaporator 105a to reduce the pressure of the refrigerant flowing through FL1 to the same pressure as the refrigerant flowing through FL2. Because the evaporator 105b is controlled within a predetermined range, the pressure of the refrigerant that has passed through the evaporator 105b can be calculated approximately. This value is set as a target value for the evaporation pressure control valve 108e, and the opening of the evaporation pressure control valve 108e is adjusted based on the deviation from the value detected by the pressure detection unit.

[0091] In this embodiment, the control unit 200 performs PID control of the opening / closing degree of the control valve 503, and can also PID control one or more of the opening / closing degree of the evaporation pressure adjustment valve 108e, the opening / closing degree of the pressure reducer 104a, and the opening / closing degree of the pressure reducer 104b. In other words, the control unit 200 controls at least the opening / closing degree of the control valve 503 by PID control among the opening / closing degrees of the control valve 503, the opening / closing degree of the evaporation pressure adjustment valve 108e, the opening / closing degree of the pressure reducer 104a, and the opening / closing degree of the pressure reducer 104b.

[0092] [Embodiment 6] In the first to fifth embodiments, the temperature and pressure detected by the detection means are substituted into (Equation 1) to (Equation 4) for control without processing, but in this embodiment, a moving average process is performed on the acquired values ​​before substituting the temperature and pressure detected by the detection means into (Equation 1) to (Equation 4). This process can create differences in the control response speed of each control device.

[0093] For example, in the configuration of embodiment 1 illustrated in Fig. 1, the degree of superheat calculated to control pressure reducers 104a and 104b is obtained as follows: First, control unit 200 acquires the refrigerant pressure or temperature detected by detection unit 118 and detection unit 119 multiple times and calculates a moving average, and then control unit 200 calculates the degree of superheat based on the calculated moving average of the pressure or temperature.

[0094] In this embodiment, instead of calculating the degree of superheat based on only a single detected value, the pressure or temperature is acquired multiple times, and a moving average of the pressure or temperature is calculated before calculating the degree of superheat. This suppresses the amount of change in the pressure or temperature, thereby creating a difference in the control response speed between the pressure reducer 104a and the pressure reducer 104b. As a result, hunting is more effectively suppressed.

[0095] Similarly, in controlling the evaporation pressure control valve 108a, the temperature of the cooled object 113 cooled by the evaporator 105a is detected multiple times by the temperature detection unit 117, input to the control unit 200 to calculate a moving average, and then the refrigerant pressure is calculated based on the calculated moving average of the temperature. In this way, instead of calculating the pressure based on only a single detected value, the temperature is obtained multiple times and the moving average of the temperature is calculated in advance before calculating the pressure. This suppresses the amount of temperature change, allowing for a margin in setting the control response speed of the evaporation pressure control valve 108a. As a result, the hunting suppression effect is enhanced.

[0096] If the time intervals at which the detected values ​​are obtained from each detection means are equal, it is preferable to set the numbers of detected values ​​used to calculate the moving average between different detection means so that they are relatively prime values. This makes it possible to reduce overlap in the control periods of the control objects (compressor 102, pressure reducer 104a, pressure reducer 104b, and evaporation pressure control valve 108a), thereby further increasing the effect of suppressing hunting.

[0097] When performing the moving average process, if the number of detected values ​​used to calculate the moving average is less than the set number, the average value of all the acquired detected values ​​is used instead, and when the number of detected values ​​becomes equal to or greater than the set value, the moving average process is performed. The table shown in Figure 7A and the graph shown in Figure 7B illustrate an example of a calculation method when the number of detected values ​​to be used for the moving average process is "5".

[0098] In addition, the number of detection values ​​used to calculate the moving average is set to satisfy (Equation 6), where i1 is the number of times the pressure or temperature of the refrigerant detected by the detection unit 119 is obtained, i2 is the number of times the pressure or temperature of the refrigerant detected by the detection unit 118 is obtained, and i3 is the number of times the temperature of the cooled object 113 is obtained by the temperature detection unit 117 or the number of times the pressure is obtained by the pressure detection unit 120.

[0099] (Formula 6) i3>i2>i1>1

[0100] Here, moving average processing is not performed on the temperature used to control the rotation speed of the compressor 102, i.e., the temperature of the cooled object 114 acquired by the temperature detection unit 116, because rapid and precise control is required. By setting the temperature in this manner, as in the first to fifth embodiments, the control response speed of the compressor 102 can be made faster than the control response speed of the pressure reducer 104b, the control response speed of the pressure reducer 104a, and the control response speed of the evaporation pressure control valve 108a. Furthermore, the control response speed of the pressure reducer 104b can be made slower than the control response speed of the compressor 102 and faster than the control response speeds of the pressure reducer 104a and the evaporation pressure control valve 108a. Furthermore, the control response speed of the pressure reducer 104a can be made slower than the control response speed of the compressor 102 and the control response speed of the pressure reducer 104b, and faster than the control response speed of the evaporation pressure control valve 108a. Furthermore, the control response speed of the evaporation pressure regulating valve 108a can be made slower than the control response speed of the compressor 102, the control response speed of the pressure reducer 104b, and the control response speed of the pressure reducer 104a. ｐ１ , K. ｐ２ , K. ｐ３ , K. ｐ４It is sufficient to set it so that the order of the control response speeds generated by Equation 6 does not change, and it is not necessary to set it as in Equation 5.

[0101] In this embodiment, a case where the configuration of embodiment 1 is applied is shown, but this is not limited to this. Even if the number of refrigeration cycles increases, the number of measurements acquired for moving average processing can be reduced as the value input to the control device increases in response speed.

[0102] [Other Embodiments] The present invention is not limited to the above-described embodiments, and many modifications are possible within the technical spirit of the present invention. For example, the above-described different embodiments may be combined in whole or in part.

[0103] In the first embodiment, a first refrigeration cycle for cooling, for example, a liquid, and a second refrigeration cycle for cooling, for example, air, are installed side by side, sharing a compressor and a condenser. The second refrigeration cycle for cooling, for example, air, is configured to have the highest cooling capacity and the highest temperature control accuracy. In the second embodiment, a third refrigeration cycle is also installed side by side, and in the third embodiment, a fourth refrigeration cycle is also installed side by side. In both cases, the second refrigeration cycle for cooling, for example, air, is configured to have the highest cooling capacity and the highest temperature control accuracy.

[0104] In implementing the present invention, the number of refrigeration cycles installed side by side is not limited to the above example, and more refrigeration cycles may be installed side by side. Each refrigeration cycle (evaporator) may cool different types of objects or objects with different heat capacities, or objects of the same type or with the same heat capacity. When arranging multiple control devices, increasing the control response speed from the upstream side and in order of increasing refrigerant flow rate can prevent hunting and stabilize the refrigerant flow. This allows the temperature of the object to be precisely adjusted within, for example, a 0.1°C range from the set point in the refrigeration cycle with the largest cooling capacity. While the example shown here illustrates a refrigeration cycle configured to maximize cooling capacity and maximize temperature control accuracy, the object to be cooled is not limited to air and may be other gases or liquids.

[0105] The present invention can also be realized by supplying a program that realizes one or more functions of the embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0106] The present invention can be suitably implemented as a cooling device for cooling heat-generating parts in various industrial equipment having multiple heat-generating parts that require cooling, such as an exposure machine for semiconductor manufacturing. In particular, the present invention can be suitably implemented in various industrial equipment having multiple heat-generating parts with different heat values. The present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, in order to disclose the scope of the present invention, the following claims are appended.

[0107] 19...External equipment / 20...Exposure device / 21...Control circuit system / 22...Drive power system / 23...Optical unit / 24...Atmosphere / 25, 26...Pump / 27...Blower / 28...Chamber / 101...Cooling device / 102...Compressor / 103...Condenser / 104a-104d...Decompressor / 105a-105d...Evaporator / 112...Confluence / 115...Branch / 116...Temperature detection unit / 117...Temperature detection unit / 118...Detection unit / 119...Detection unit / 121...Cooling device / 128...Cooling device / 200...Control unit / 501...Branch / 502...Confluence / 503...Control valve

Claims

a first refrigeration cycle including a compressor for compressing a refrigerant, a condenser for cooling and condensing the refrigerant compressed by the compressor, a first pressure reducer, and a first evaporator, and causing the refrigerant reduced in pressure by the first pressure reducer to flow into the first evaporator to cool an object to be cooled; a second refrigeration cycle including the compressor, the condenser, a second pressure reducer, a second evaporator, and an evaporation pressure regulating valve, and causing a flow rate of refrigerant greater than that of the first pressure reducer to be reduced in pressure by the second pressure reducer and flow into the second evaporator to cool an object to be cooled; and a control unit; the first refrigeration cycle includes, as viewed along the direction of refrigerant flow, a common flow path in which the compressor and the condenser are connected in this order, and a first flow path in which the first pressure reducer and the first evaporator are connected in this order; and the second refrigeration cycle includes, as viewed along the direction of refrigerant flow, the common flow path, and a second flow path in which the second pressure reducer, the second evaporator, and the evaporation pressure regulating valve are connected in this order; the common flow path branches into the first flow path and the second flow path at a branch point located downstream of the condenser, the first flow path downstream of the first evaporator and the second flow path downstream of the evaporation pressure regulating valve join at a junction point and connect to the common flow path upstream of the compressor, the control unit controls the operation of the compressor based on a temperature of the object to be cooled (2) cooled by the second evaporator, obtains a degree of superheat 1 that is a degree of superheat of the refrigerant from a temperature and / or pressure of the refrigerant downstream of the first evaporator in the first flow path and controls the opening / closing degree of the first pressure reducer based on the degree of superheat 1, obtains a degree of superheat 2 that is a degree of superheat of the refrigerant from the temperature and / or pressure of the refrigerant downstream of the second evaporator in the second flow path and controls the opening / closing degree of the second pressure reducer based on the degree of superheat 2, and controls the opening / closing degree of the evaporation pressure regulating valve based on a target pressure of the refrigerant downstream of the evaporation pressure regulating valve or the temperature of the object to be cooled (1) cooled by the first evaporator.

2. The cooling device described in claim 1, wherein the control unit controls each of the drive of the compressor, the opening / closing degree of the first pressure reducer, the opening / closing degree of the second pressure reducer, and the opening / closing degree of the evaporation pressure regulating valve by PID control.

3. A cooling device as described in claim 2, wherein a proportional control constant when PID controlling the compressor is Kp1, a proportional control constant when PID controlling the opening / closing degree of the second pressure reducer is Kp2, a proportional control constant when PID controlling the opening / closing degree of the first pressure reducer is Kp3, and a proportional control constant when PID controlling the opening / closing degree of the evaporation pressure regulating valve is Kp4, and the relationship Kp1>Kp2>Kp3>Kp4 holds.

4. A cooling device as claimed in any one of claims 1 to 3, wherein a control response speed of the compressor is RS1, a control response speed of the second pressure reducer is RS2, a control response speed of the first pressure reducer is RS3, and a control response speed of the evaporation pressure regulating valve is RS4, and the relationship RS1 > RS2 > RS3 > RS4 holds.

5. A cooling device as described in any one of claims 1 to 4, wherein the first refrigeration cycle comprises: a first detection means for detecting the temperature and / or pressure of the refrigerant, provided between the first evaporator and the junction; and a first temperature detection unit for detecting the temperature of the object 1 cooled by the first evaporator; and the second refrigeration cycle comprises: a second detection means for detecting the temperature and / or pressure of the refrigerant, provided between the second evaporator and the evaporation pressure regulating valve; a third detection means for detecting the pressure of the refrigerant, provided between the evaporation pressure regulating valve and the junction; and a second temperature detection unit for detecting the temperature of the object 2 cooled by the second evaporator.

6. The cooling device described in claim 5, wherein the control unit controls the operation of the compressor using the detection result of the second temperature detection unit, controls the opening / closing degree of the first pressure reducer using the detection result of the first detection means, controls the opening / closing degree of the second pressure reducer using the detection result of the second detection means, and controls the opening / closing degree of the evaporative pressure control valve using the detection result of the third detection means or the first temperature detection unit.

7. The cooling device described in claim 5, wherein the control unit controls the operation of the compressor using the detection result of the second temperature detection unit, controls the opening / closing degree of the first pressure reducer using a moving average of the detection result of the first detection means, controls the opening / closing degree of the second pressure reducer using a moving average of the detection result of the second detection means, and controls the opening / closing degree of the evaporative pressure control valve using a moving average of the detection result of the third detection means or the first temperature detection unit.

8. The cooling device as described in claim 7, wherein the number of detection values ​​used when calculating a moving average of the detection results of the second detection means is i1, the number of detection values ​​used when calculating a moving average of the detection results of the first detection means is i2, and the number of detection values ​​used when calculating a moving average of the detection results of the third detection means or the first temperature detection unit is i3, and the relationship i3>i2>i1>1 holds.

9. The cooling device of claim 8, wherein i1, i2, and i3 are mutually prime.

10. A cooling device as described in any one of claims 1 to 9, further comprising a third refrigeration cycle including the compressor, the condenser, a third pressure reducer, a third evaporator, and a second evaporation pressure regulating valve, in which a refrigerant with a flow rate smaller than that of the second pressure reducer is reduced in pressure by the third pressure reducer and flows into the third evaporator to cool an object to be cooled 3, wherein the opening and closing degree of the third pressure reducer is set so that the evaporation pressure of the third evaporator is greater than the evaporation pressure of the first evaporator and less than the evaporation pressure of the second evaporator.

11. A first refrigeration cycle including a compressor that compresses a refrigerant, a condenser that cools and condenses the refrigerant compressed by the compressor, a first pressure reducer, a first evaporator, and an evaporation pressure regulating valve, in which the refrigerant reduced in pressure by the first pressure reducer flows into the first evaporator to cool an object to be cooled 1; a second refrigeration cycle including the compressor, the condenser, a second pressure reducer, and a second evaporator, in which a flow rate of refrigerant greater than that of the first evaporator flows into the second evaporator to cool an object to be cooled 2; and a control unit, wherein the first refrigeration cycle includes, as viewed along the direction of refrigerant flow, a common flow path in which the compressor and the condenser are connected in this order, and a first flow path in which the first pressure reducer, the first evaporator, and the evaporation pressure regulating valve are connected in this order; the second refrigeration cycle comprises, as viewed along a flow direction of the refrigerant, the common flow path, a second flow path in which the second pressure reducer and the second evaporator are connected in this order, and a hot gas bypass branching from the common flow path between the compressor and the condenser and connecting to the second flow path between the second pressure reducer and the second evaporator via a control valve, the common flow path branching into the first flow path and the second flow path at a branching point located downstream of the condenser, the first flow path downstream of the evaporation pressure regulating valve and the second flow path downstream of the second evaporator joining at a joining point and connecting to the common flow path upstream of the compressor, the control unit controlling the opening / closing degree of the control valve of the hot gas bypass based on the temperature of the object to be cooled 2 cooled by the second evaporator, obtaining a degree of superheat 1 which is a degree of superheat of the refrigerant from a temperature and / or pressure of the refrigerant downstream of the first evaporator of the first flow path and controlling the opening / closing degree of the first pressure reducer based on the degree of superheat 1, a degree of superheat 2 of the refrigerant is obtained from a temperature and / or pressure of the refrigerant downstream of the second evaporator in the second flow path, and an opening / closing degree of the second pressure reducer is controlled based on the degree of superheat 2; and an opening / closing degree of the evaporation pressure control valve is controlled based on a target pressure of the refrigerant downstream of the evaporation pressure control valve.

12. The cooling device described in claim 11, wherein the control unit controls at least the opening / closing degree of the control valve by PID control, out of the control of the opening / closing degree of the control valve, the control of the opening / closing degree of the first pressure reducer, the control of the opening / closing degree of the second pressure reducer, and the control of the opening / closing degree of the evaporation pressure regulating valve.

13. An exposure apparatus comprising a cooling device according to any one of claims 1 to 12.

14. Industrial equipment comprising a cooling device according to any one of claims 1 to 12.

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