JP4328892B2 - Temperature and humidity control device and environmental test device - Google Patents

Description

  The present invention relates to a temperature control device and an environmental test device.

  The environmental test apparatus is used when testing temperature characteristics and humidity characteristics of various test objects such as electronic parts, automobile parts, and chemical substances. In general, an environmental test apparatus includes a test room in which a sample to be tested is installed, and a temperature control apparatus that adjusts the temperature and humidity in the test room. This temperature control apparatus is provided with, for example, a heater for heating the test chamber and a humidifier for humidifying. The cooling and dehumidification of the test chamber is performed by the evaporator of the refrigeration cycle, so that the test chamber is maintained at, for example, constant temperature and humidity.

  By the way, if the test chamber is set to a low temperature or a low humidity, the evaporator of the refrigeration cycle may be frosted. When the evaporator is frosted, the effect of cooling and dehumidification is reduced, and the test chamber cannot be maintained at constant temperature and humidity. Therefore, it is necessary to interrupt the test and perform the defrosting operation. However, since the environmental test apparatus is generally used continuously for, for example, 2 to 24 hours, it cannot often be defrosted. Therefore, in order to increase the interval between defrosting operations, the fin pitch interval is increased in the cross fin tube type evaporator so that the cooling and dehumidifying effects can be maintained even if some frost formation occurs. It has been broken.

  On the other hand, in order to prevent the frost formation of the evaporator, a pressure reducing valve for adjusting the evaporation temperature of the evaporator is provided in the gas refrigerant flow path between the evaporator and the compressor so that the evaporation temperature of the evaporator is higher than the frost temperature. Have been proposed that perform so-called no-frost operation (see, for example, Patent Document 1).

JP-A-8-278071 (page 2-4, FIG. 1)

  However, since the pressure reducing amount of the pressure reducing valve of Patent Document 1 is fixed, the evaporation temperature varies due to a disturbance such as a change in ambient temperature (for example, 2 to 3 ° C.), and the evaporator may be frosted. Thereby, there exists a possibility that the temperature and humidity in the test chamber which is a target room for temperature and humidity control may fluctuate.

  This invention makes it a subject to avoid the frost formation to the evaporator of the refrigerating cycle which performs temperature-control humidity control of a target chamber, and to suppress the fluctuation | variation of the temperature and humidity of a target chamber.

The present invention solves the above problems by the following means. That is, in a temperature control humidity control apparatus having a refrigerator that circulates air in a target room through an evaporator constituting a refrigeration cycle and controls the temperature and humidity in the target room, the liquid refrigerant circulated through the evaporator a constant pressure reducing valve for reducing the pressure, and the solenoid valve connected in series with the constant pressure reducing valve, a variable pressure reducing valve connected to said parallel to the series connection passage between the constant pressure reducing valve the solenoid valve, the variable vacuum A controller for controlling the opening of the valve, and the controller closes the electromagnetic valve and controls the opening of the variable pressure reducing valve when the target temperature of the target chamber is equal to or lower than the first temperature. To control a target value of the temperature in the target chamber, and when the target value exceeds the first temperature, the solenoid valve is opened and the opening of the variable pressure reducing valve is adjusted to the evaporation temperature of the evaporator. The detection value is controlled to a set temperature that is set to a temperature exceeding the frosting temperature. .

Thereby, when the target value of the temperature in the target chamber exceeds the first temperature (for example, 10 ° C.), the solenoid valve is opened to depressurize the refrigerant through the constant pressure reducing valve, and the opening of the variable pressure reducing valve Since the detected value of the evaporation temperature of the evaporator is controlled to a set temperature that is set to a temperature that exceeds the frosting temperature, even if there is a disturbance such as a change in the ambient temperature, the set temperature at which the evaporation temperature does not frost Therefore, the temperature and humidity in the target room can be stably controlled. Further, since the evaporation temperature is variably controlled so as to maintain the evaporation temperature at the set temperature, frost formation can be prevented even if the set temperature is set close to the frost temperature. That is, the area of no frost operation can be expanded to the low temperature side or the low humidity side.

In addition , since the variable pressure reducing valve is connected in parallel to the series connection flow path of the constant pressure reducing valve and the solenoid valve, the refrigerant is decompressed by the constant pressure reducing valve when the solenoid valve is opened. Subtle adjustment of the heat generation temperature is possible, and fluctuations in temperature and humidity in the target room can be further suppressed. Here, if the constant pressure reducing valve and the variable pressure reducing valve are provided in the liquid side flow path of the evaporator, the solenoid valve is opened when the no frost operation is performed, and the solenoid valve is closed when the no frost operation is not performed. The expansion valve of the refrigeration cycle can be used as a constant pressure reducing valve and a variable pressure reducing valve.

  The temperature and humidity control apparatus described above can include a blower that allows the air in the target chamber to flow through the evaporator, and a variable unit that varies the air volume of the blower. According to this, since the amount of heat transfer from the evaporator per unit flow rate of air can be adjusted by changing the air volume, the cooling capacity and the dehumidifying capacity of the evaporator can be controlled. In particular, the dehumidifying ability can be improved by reducing the air volume.

  ADVANTAGE OF THE INVENTION According to this invention, the frost formation to the evaporator of the refrigerating cycle which performs temperature control and humidity control of an object chamber can be avoided, and the fluctuation | variation of the temperature and humidity of an object chamber can be suppressed.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a temperature and humidity control apparatus and an environmental test apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a diagram illustrating a configuration of a refrigeration cycle of a temperature and humidity control apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing a configuration of an environmental test apparatus according to an embodiment of the present invention. FIG. 3 is a partial cross-sectional view showing the configuration of the temperature and humidity control apparatus of one embodiment of the present invention.

  As shown in FIG. 2, the environmental test apparatus according to the present embodiment includes a test chamber 1 and a temperature adjustment chamber device 3 assembled in the test chamber 1. The test chamber 1 is formed of, for example, a heat insulating panel, and is provided with a door 5 for loading and unloading a test sample.

  The temperature control device 3 includes a unit 7 that actually adjusts the temperature and humidity in the test chamber 1, and a control panel 9 that controls the unit 7. The unit 7 includes a box-shaped housing 10 as shown in FIG. The housing 10 has a suction port 11 and a blower port 12 communicating with the test chamber 1. A blower 15 that sends the air in the housing 10 to the air outlet 12 is provided in the housing 10. Further, the housing 10 is provided with an evaporator 13, a heater 17 and a humidifier 19 for the refrigeration cycle. The refrigerator, the heater 17 and the humidifier 19 having the refrigeration cycle are output by the control panel 9. Adjusted temperature and humidity can be adjusted. The heater 17 is composed of, for example, an electric heater, and the humidifier 19 is composed of, for example, an electric heater attached to a dish filled with water.

  As shown in FIG. 1, the refrigeration cycle includes a compressor 23, a condenser 25, an electronic expansion valve 27, and an evaporator 13. The compressor 23 is capable of capacity control. A condenser 25 is connected to the discharge side of the compressor 23. The liquid side flow path of the condenser 25 is connected to the evaporator 13 via the electronic expansion valve 27. The gas side flow path of the evaporator 13 is connected to the suction side of the compressor 23. In the present embodiment, a liquid receiver 29 is provided in the refrigerant flow path between the condenser 25 and the electronic expansion valve 27. A suction pressure adjusting valve 33 that adjusts the suction pressure of the compressor 23 is provided in the refrigerant flow path on the suction side of the compressor 23.

  The feature of this embodiment is that the evaporation temperature (evaporation pressure) of the refrigerant in the evaporator is adjusted, and the detected value of the evaporation temperature of the evaporator is controlled to a set temperature that is set to a temperature exceeding the frosting temperature. In order to realize this control, a thermometer 35 for detecting the evaporation temperature and a controller 37 for controlling the opening degree of the electronic expansion valve 27 based on the detected temperature are provided. The thermometer 35 is attached to the liquid side flow path of the evaporator 13, for example.

  A refrigerant flow path 39 that bypasses the electronic expansion valve 27 is provided, and a constant pressure expansion valve 41 that is a constant pressure reducing valve is provided in the refrigerant flow path 39. That is, the electronic expansion valve 27 and the constant pressure expansion valve 41 are connected in parallel. The opening degree of the constant pressure expansion valve 41 is higher than the temperature at which the frost adheres to the evaporator 13 when the compressor 23 is operated at the maximum capacity, that is, higher than the frosting temperature. The opening is fixed at the set temperature. This set temperature is not simply set to 0 ° C., but can be set to 0 to −5 ° C., for example, considering that frost is melted by the heat of air. The refrigerant flow path 39 is provided with an electromagnetic valve 43. Thereby, it is possible to switch to the operation of only the electronic expansion valve 27 or the operation of using the electronic expansion valve 27 and the constant pressure expansion valve 41 together.

  The operation of the environmental test apparatus configured as described above will be described. First, the air in the test chamber 1 is sucked from the suction port 12 by the blower 15 and passes through the humidifier 19, the evaporator 13, and the heater 17, so that air conditioning of humidification or dehumidification and heating or cooling is achieved. Then, the air is blown out from the air outlet 11 to the test chamber 1. The air temperature and humidity are controlled to target values set in the control panel 9. For example, on the air side of the test chamber 1, the outputs of the heater and the humidifier are controlled (for example, PID control based on time proportionality) in accordance with the deviation amount between the temperature and humidity detected at the air outlet 11 and the target value. Thereby, the inside of the test chamber 1 can be made into arbitrary conditions, for example, temperature and humidity can be changed at constant temperature and humidity or a constant change rate.

  In the refrigeration cycle, the refrigerant gas compressed by the compressor 23 is condensed by the condenser 25, and the liquid refrigerant discharged from the condenser 25 is decompressed by the electronic expansion valve 27 and guided to the evaporator 13. The liquid refrigerant guided to the evaporator 13 evaporates by exchanging heat with the air flowing around the evaporator 13. Thereby, the air around the evaporator 13 is cooled or dehumidified. The gas refrigerant discharged from the evaporator 13 is sucked into the compressor 23 and circulated.

  Here, if the target value of the temperature set in the control panel 9 is low (for example, 10 ° C. or lower), the evaporation temperature of the evaporator 13 must be lower than the frosting temperature in order to cool to the target temperature. There is a case. In this case, by closing the solenoid valve 43, the evaporation pressure of the evaporator 13 is reduced, and a so-called frost operation is performed in which the evaporation temperature is operated below the frosting temperature.

  On the other hand, if the target value of the temperature set in the control panel 9 is set relatively high (for example, the temperature is 10 to 60 ° C.), the desired temperature can be obtained without reducing the evaporation temperature of the evaporator 13 below the frosting temperature. Cooling capacity and dehumidifying capacity can be obtained. In this case, the solenoid valve 43 is opened, and the constant pressure expansion valve 41 and the electronic expansion valve 27 are used together. Thereby, the evaporation temperature of the evaporator 13 is adjusted to a set temperature (for example, 0 to −5 ° C.) set in the constant pressure expansion valve 41. Further, the controller 37 adjusts the opening degree of the electronic expansion valve 27 to control the evaporation temperature detected by the thermometer 35 to a set temperature that is set to be the same as the set temperature of the constant pressure expansion valve. As a result, the evaporation temperature is maintained at the set temperature.

  As described above, according to the present embodiment, for example, even if there is a disturbance such as a change in the ambient temperature of the test chamber 1 or the condenser 25, the evaporation temperature is set to a set temperature at which the evaporating temperature does not frost by feedback control of the electronic expansion valve 27. Since it is maintained, frost formation can be completely avoided, and fluctuations in temperature and humidity in the test chamber 1 can be suppressed. Thereby, an environmental test can be performed for a long time at a stable temperature and humidity.

  Furthermore, in this embodiment, since the evaporation pressure is controlled so as to maintain the evaporation temperature at the set temperature, frost formation does not occur even if the set temperature is set close to the frost temperature. Therefore, as shown in FIG. 4, the area of the no frost operation can be expanded to the low temperature side and the low humidity side.

  Further, in this embodiment, since the evaporation temperature is controlled by one of two valves provided in parallel, that is, an electronic expansion valve, the evaporation temperature can be delicately set and adjusted. Control can be performed without frost formation. In this case, if the capacity of the electronic expansion valve 27, that is, the valve opening, has a sufficient margin, the no-frost operation can be performed by independent control of the electronic expansion valve 27 without using the constant pressure expansion valve 41 together.

  In the present embodiment, the air volume of the blower 15 is not adjusted, but instead, a variable means such as an inverter for changing the air volume of the blower 15 can be provided. According to this, for example, since the bypass factor of the evaporator 13 can be adjusted by changing the air volume, the dehumidifying ability of the evaporator 13 can be controlled. In particular, the region that can be operated with no frost can be expanded to the low humidity side, which is preferable.

  Specifically, in a region where the dehumidifying capacity is not so necessary, that is, a region where the relative humidity at the target temperature exceeds 50%, the blower 15 is normally operated (for example, 50 to 90 Hz) and the relative humidity is 50% or less. Therefore, consideration is given to maintaining the dehumidifying capacity by switching the low speed operation (for example, 30 to 40 Hz) according to the set temperature, thereby changing the bypass factor of the evaporator small by controlling the air volume. Further, instead of simply switching only relative humidity to the reference, as shown in FIG. 5, considering the temperature in the test chamber 1, a limit line for starting low-speed operation as the target temperature increases is set to low humidity. It may be shifted to the side area. In addition, if the air volume control by the low speed operation described above is performed after the test chamber 1 reaches the target temperature (for example, within ± 1 ° C. of the target temperature), the temperature drop time is reduced due to the decrease in the cooling capacity accompanying the decrease in the air volume. It is preferable because it can eliminate the adverse effect on the surface.

  In the present embodiment, an electric heater is used as the heater 17, but the present invention is not limited to this, and it is only necessary to be able to control the output. Similarly, the humidifier 19 need only be capable of output control, and is not limited to the evaporation type of the present embodiment, and an ultrasonic humidifier or the like can be used. Further, in the present embodiment, for example, heat exchange is performed between the low-pressure side refrigerant and the high-pressure side refrigerant using a double pipe heat exchanger to promote gasification of the low-pressure side refrigerant, A known technique such as supercooling can also be applied. Furthermore, it is possible to remove moisture and foreign substances contained in the refrigerant by providing a dryer, strainer, or the like in the liquid refrigerant flow path. Also, so-called liquid injection can be performed in order to control the superheat with respect to the condensation temperature of the discharged gas temperature of the compressor 23 to be constant.

  As described above, according to the present embodiment, the area of no frost operation can be expanded to the low temperature side and the low humidity side, and the temperature and humidity area conventionally performed in frost operation can be covered with no frost operation. . For this reason, conventionally, as a countermeasure against frost formation, in the cross fin tube type evaporator, the interval of the fin pitch, which has been set wider (for example, 8 mm pitch), can be narrowed. Thereby, downsizing can be realized. In addition, the fin of the cross fin tube is formed by deep drawing a hole for inserting the heat transfer tube into the fin to form a cylindrical color height equal to the fin pitch. It is preferable to specify. However, if the fin pitch interval is 8 mm, the color height cannot be formed with the copper plate or aluminum plate of 0.1 to 0.2 mm thickness usually used for fins due to the limit of deep drawing. It took time and effort to make a separate height. In this respect, according to the present embodiment, the fin pitch can be deep drawn with a normal fin, for example, 4 mm, so that the manufacturing process can be facilitated.

It is a figure which shows the structure of the refrigerating cycle of the temperature control apparatus of one Embodiment of this invention. It is a figure which shows the structure of the environmental test apparatus of one Embodiment of this invention. It is a partial cross section figure which shows the structure of the temperature control apparatus of one Embodiment of this invention. The vertical axis represents relative humidity, the horizontal axis represents temperature, and is a graph for explaining a no-frost region. It is the graph which showed the target humidity on the vertical axis | shaft, the target temperature on the horizontal axis | shaft, and showed the limit line which switches the air volume of a fan.

Explanation of symbols

13 Evaporator 23 Compressor 25 Condenser 27 Electronic Expansion Valve 35 Thermometer 37 Controller 41 Constant Pressure Expansion Valve 43 Solenoid Valve

Claims (4)

In a temperature control apparatus equipped with a refrigerator that circulates air in a target room through an evaporator constituting a refrigeration cycle and controls the temperature and humidity in the target room,
Connected to a constant pressure reducing valve for reducing the pressure of the liquid refrigerant is circulated to the evaporator, and an electromagnetic valve connected in series with the constant pressure reducing valve, in parallel with the series connection channel of the the constant pressure reducing valve the solenoid valve A variable pressure reducing valve, and a controller for controlling the opening of the variable pressure reducing valve,
When the target value of the temperature in the target chamber is equal to or lower than the first temperature, the controller closes the electromagnetic valve and controls the opening of the variable pressure reducing valve to control the target value of the temperature in the target chamber. When the target value exceeds the first temperature, the solenoid valve is opened, and the opening of the variable pressure reducing valve is set to a temperature exceeding the frosting temperature as the detected value of the evaporation temperature of the evaporator. A temperature and humidity control device that is controlled to a set temperature.   The temperature and humidity control apparatus according to claim 1, further comprising: a blower that allows the air in the target chamber to flow through the evaporator; and a variable unit that varies an air volume of the blower.   The temperature control apparatus according to claim 1 or 2, comprising a heater for heating the air in the target chamber and a humidifier for humidifying the air in the target chamber.   The environmental test apparatus provided with the temperature-control humidity control apparatus of any one of Claims 1 thru | or 3.

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