JPH05126414A - Refrigerator and apparatus for constant-temperature and constant-humidity - Google Patents

Abstract

PURPOSE:To obtain the required temperature for evaporating refrigerant even when the ambient temperature of a refrigerator is high and apply this possibility to an apparatus for constant temperature and constant humidity in maintaining the minimum temperature in a laboratory. CONSTITUTION:A device-control microcomputer calculates the comparison of a temperature detected by a refrigerant-evaporation temperature sensor 15 with a set temperature and a pulse signal corresponding to the difference therebetween is transmitted by a pulse-based adjuster to an electronic proportional control valve 12 as a command for changing the valve opening. Therefore, without being affected by changes in the ambient temperature, the refrigerant- evaporation temperature at an evaporator 13 can be maintained at a specified point in a stabilized state. When the ambient temperature rises high, the evaporation temperature is lowered to a specified point so that the inside of a laboratory consisting of an apparatus for constant temperature and constant humidity can be kept at the specified minimum temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus and a constant temperature / humidity apparatus using the refrigerating apparatus, and more particularly to a technique for controlling the temperature of a refrigerant at the outlet of a pressure reducing means of the refrigerating apparatus.

[0002]

2. Description of the Related Art Conventionally, as a decompression mechanism for a refrigeration system using a refrigeration cycle, there is a system using a capillary tube or a thermal expansion valve, including a system used in a constant temperature / constant humidity tank as an environmental test device. It was common.

[0003]

When ambient air or cooling water is used as a medium for cooling the condenser, the higher the ambient temperature of the apparatus, the higher the cooling air temperature and the cooling water temperature, and the higher the cooling medium temperature. Condensation temperature rises. In such a case, if a decompression mechanism such as the capillary tube or the thermal expansion valve as described above is used, the temperature after decompression, that is, the evaporation temperature also rises as the condensation temperature rises. To prevent this,
Supposing that the decompression amount of the capillary tube or the thermal expansion valve is determined so that the required low evaporation temperature can be obtained even when the condensation temperature of the refrigerant is high, when the ambient temperature is low and the refrigerant condensation temperature is low, The evaporating temperature drops abnormally, causing damage to the compressor.

On the other hand, in the constant temperature / constant humidity apparatus, the minimum temperature to be reached in the test chamber is defined as a basic performance. Then, in order to achieve the minimum temperature by cooling the inside of the constant temperature / humidity device by using the refrigerating device as the cooling means of the constant temperature / humidity device, the refrigerant evaporation temperature of the refrigeration cycle is set to the minimum temperature. On the other hand, it is necessary to make the temperature lower than the appropriate temperature difference. Therefore, when a capillary tube or a thermal expansion valve, which is a conventional decompression mechanism, is used in the refrigerating apparatus of such a constant temperature / constant humidity apparatus, there is a problem that a low refrigerant evaporation temperature required when the ambient temperature is high cannot be obtained. is there.

Therefore, the present invention solves the above problems in the prior art, and an object thereof is to provide a refrigerating apparatus which can obtain a necessary refrigerant evaporation temperature even when the ambient temperature is high, and when the ambient temperature is high. Also, it is an object of the present invention to provide a constant temperature / constant humidity device which can obtain a necessary refrigerant evaporation temperature and can bring a space region covered with a heat insulating layer to a predetermined minimum temperature.

[0006]

In order to solve the above-mentioned problems, the present invention provides a first aspect of the present invention in which a refrigerant is compressed by a compressor and guided to a condenser and cooled by a cooling medium to be condensed. In a refrigerating apparatus in which the pressure is reduced by a pressure reducing means and is introduced to an evaporator, and which is heated by a heating medium to be evaporated and is again introduced into a compressor, the pressure reducing means is a variable opening control valve, and the pressure is reduced by the pressure reducing means. A temperature detecting means for detecting the temperature of the subsequent refrigerant; and a control means for controlling the opening of the control valve so that the temperature detected by the temperature detecting means becomes a predetermined temperature, The invention of claim 2 is characterized in that, in addition to the above, the control system of the control valve by the control means is either proportional control, proportional / integral control or proportional / integral / derivative control. That is, in order to obtain a constant cold evaporation temperature with respect to changes in the temperature of the refrigerant condenser, an electronic proportional control valve whose opening can be continuously changed is used as a pressure reducing mechanism, and Until or until the evaporator is equipped with a refrigerant evaporation temperature sensor to detect the refrigerant evaporation temperature, the calculated evaporation temperature is constantly compared with the detected temperature of the refrigerant evaporation temperature sensor, and the refrigerant evaporation temperature stabilizes at the set evaporation temperature. The problem is solved by transmitting the opening degree change command to the electronic proportional control valve so as to be maintained as it is.

According to a third aspect of the present invention, there is provided a constant temperature / humidity device for cooling the interior of a space covered with a heat insulating layer with a refrigerating device to maintain a constant temperature and humidity.
Or the refrigerating device according to claim 2, wherein the invention of claim 4 is characterized in that, in addition to the features of the invention of claims 1 to 3, the temperature detecting means is replaced by a decompressing means after decompressing. The pressure detecting means for detecting the pressure of the refrigerant is provided, and the control means controls the opening degree of the control valve so that the pressure detected by the pressure detecting means becomes a predetermined pressure. In a sixth aspect of the invention, instead of the temperature detecting means, a condensing pressure detecting means, a condensing temperature detecting means or an ambient temperature detecting means for detecting the pressure or temperature of the refrigerant condensed in the condenser or the ambient temperature is provided, and the control means is provided. Is the pressure or temperature detected by the condensing pressure detecting means, the condensing temperature detecting means, or the ambient temperature detecting means, and the predetermined condensing pressure or the condensing temperature or the ambient temperature. When there is, the opening of the control valve is controlled to a predetermined opening corresponding to the difference so that the temperature of the refrigerant after being depressurized by the depressurizing means becomes a predetermined temperature. ..

[0008]

According to the invention of claim 1 or 2, the pressure reducing means is a variable opening type control valve, and the temperature detecting means for detecting the temperature of the refrigerant after pressure reduction by the control valve is provided, and the detected temperature is predetermined. Since the control means controls the opening degree of the control valve so that the temperature becomes the temperature, for example, when the ambient environmental temperature is high and therefore the temperature of the cooling air or the cooling water to the condenser is high, the condensation pressure of the refrigerant becomes high. In accordance with this, the refrigerant evaporation temperature after decompression also increases, but the control means reduces the opening of the control valve by the detection signal of this temperature so that the pressure of the refrigerant to the evaporator corresponds to a predetermined saturation temperature. To lower the pressure,
As a result, the refrigerant evaporation temperature can be maintained at a predetermined temperature. On the other hand, when the ambient temperature becomes low, the refrigerant evaporation temperature can be similarly maintained at a predetermined temperature by increasing the opening degree of the control valve. Regarding the control of the amount of movement of the variable opening type control valve in the opening / closing direction, proportional (P) control or proportional / integral (depending on the difference between the temperature detected by the temperature detecting means and a predetermined set evaporation temperature is used. Since PI) control or proportional / integral / derivative (PID) control is performed, it is possible to control the refrigerant evaporation temperature faster and more stably.

According to the third aspect of the present invention, the refrigeration apparatus used for the constant temperature / humidity apparatus has a control valve opening increased to increase the pressure of the refrigerant to the evaporator even when the ambient environmental temperature rises. By providing a refrigerating device capable of lowering the evaporation temperature to a predetermined saturation temperature, it is possible to set a predetermined minimum temperature in the space area covered by the heat insulating layer of the constant temperature / humidity device.

According to the fourth aspect of the present invention, the pressure of the refrigerant after being decompressed by the decompression means is controlled to be a predetermined pressure. Therefore, the temperature of the refrigerant after being decompressed is also a predetermined saturation temperature corresponding to the predetermined pressure. That is, the target temperature is maintained.

According to the invention of claim 5 or 6, when there is a difference between the pressure or temperature detected by the condensing pressure detecting means, the condensing temperature detecting means or the ambient temperature detecting means and the predetermined pressure or the predetermined temperature by the control means. In order to control the opening of the control valve to a predetermined opening corresponding to the difference so that the temperature of the refrigerant after being decompressed by the decompression means becomes a predetermined temperature, it is indirect but of the refrigerant. The evaporation temperature can be set to a predetermined temperature.

[0012]

FIG. 1 shows a schematic structure of a refrigerating apparatus of the embodiment and a thermostat / humidity apparatus of the embodiment using the refrigerating apparatus.
The constant temperature / constant humidity device sends a test chamber 2 as a space area covered with the heat insulating layer 1, a compressor 9 of a refrigeration device forming a refrigeration cycle, an air condenser 10 as a condenser, and air as a cooling medium. Blower 11 for condenser, electronic proportional control valve 12 as an example of variable opening type control valve as pressure reducing means, evaporator 13 installed in test chamber 2, heating heater 7 for heating control, humidifying heater for humidification control. 8, a circulation blower 5 and the like. In the test chamber 2, air serving as a heating medium circulates in the evaporator 13 as shown by a flow 6 of air.

A dry-bulb temperature sensor 3 and a wet-bulb temperature sensor 4 are arranged at the blow-out port of the circulation blower 5, and the piping path to the evaporator 13 at the refrigerant outlet side of the electronic proportional control valve 12 is further provided. A refrigerant evaporation temperature sensor 15 as a temperature detecting means is attached. The arrow 14 indicates the flow direction of the refrigerant in the refrigeration system.

FIG. 2 is a block diagram showing the entire control system of the constant temperature / humidity device. The detected temperature and humidity detected by the dry-bulb temperature sensor 3 and the wet-bulb temperature sensor 4 are compared and calculated with the set temperature and humidity by the device control microcomputer 16, and the temperature controller 17 and the humidity controller 18 use the PID.
By control, signals for controlling the output of the heating heater 7 and the humidifying heater 8 are given through the thyristors 19 and 20, respectively. As a result, highly accurate temperature / humidity control in the test room 2 is possible.

On the other hand, on the refrigeration cycle side used for dehumidifying and cooling in the test chamber 2, the device control microcomputer 16
Thus, a comparison calculation is performed between the temperature detected by the refrigerant evaporation temperature sensor 15 and a preset evaporation temperature specified in the specifications of the apparatus, and the pulse controller 21 operates as an opening change command of the electronic proportional control valve 12. The amount of pulse signal is determined and transmitted.
That is, the device control microcomputer 16 and the pulse controller 21
Is an example of control means for controlling the opening of the control valve.

FIG. 3 is a flow chart showing an example of opening control of the electronic proportional control valve 12. The opening of the electronic proportional control valve 12 changes depending on the amount of pulse signals, and the larger the amount of pulses, the more the opening control is performed. Thereafter, the detected temperature of the refrigerant evaporation temperature sensor 15 and the set evaporation temperature determined in advance in the device specifications are constantly compared and calculated. When the detected temperature is high, the number of pulses is decreased, and conversely when the detected temperature is low. The number of pulses is increased to determine the optimum number of pulses to be transmitted to the electronic proportional control valve 12 by PID control of this increase / decrease amount, and by periodically transmitting to this, the refrigerant evaporation temperature is set to the set evaporation temperature. If possible, it is possible to drive the vehicle closer to and to match. That is, when the operation of the refrigerator is started (S-1), at the same time, the electronic proportional control valve 12 is set to the initial setting opening (S-2), and the device control microcomputer 16 receives the information from the refrigerant evaporation temperature sensor 15 from the refrigerant evaporation temperature sensor 15. When the detected temperature signal is input, this temperature is compared with the preset evaporation temperature determined in advance in the device specifications in the device control microcomputer 16 (S-3), and the pulse signal is PID-controlled by the pulse controller 21. Is transmitted (S-4), and the opening degree change is given to the electronic proportional control valve 12 (S-5). The control method may be simpler PI control or P control instead of PID control.

FIG. 4 shows how the condensation temperature, the evaporation temperature and the test chamber temperature change when the ambient temperature changes. When the ambient temperature changes and the condensation temperature changes, in the conventional capillary tube or the thermal expansion valve, the evaporation temperature changes accordingly, and as a result, when the ambient temperature becomes 20 ° C. or higher,
It becomes impossible to maintain the test room temperature at a constant temperature of -40 ° C. On the other hand, when the electronic proportional control valve and its control device according to the present invention are used, the evaporation temperature and the test chamber temperature can be maintained at constant values as shown in the figure.

In the above, the refrigerant evaporation temperature sensor 15 is provided, and the device control microcomputer 16 and the pulse controller 21 are provided.
Thus, the electronic proportional control valve 12 was controlled so that the refrigerant evaporation temperature reaches the set value. However, since the saturation temperature and the saturation pressure of the refrigerant have a constant relationship, the refrigerant evaporation temperature sensor 15
Instead of, the pressure detector for detecting the pressure of the refrigerant reduced by the electronic proportional control valve 12 is provided, and the opening of the control valve 12 is controlled so that the detected pressure becomes the set pressure. Good. Also, the ambient temperature changes and the condenser 10
When the temperature of the cooling air or the cooling water to the refrigerant changes, the condensation pressure and temperature of the refrigerant in the condenser 10 change, and the outlet pressure and temperature of the electronic proportional control valve 12 change correspondingly. Changes in pressure or temperature or ambient temperature, and when they change, electronic proportional control valve 12
By controlling the opening of the valve, the relationship with the valve opening that can set the outlet temperature to a set value is known in advance, and a condensing refrigerant pressure detector, a condensing refrigerant temperature detector, or an ambient temperature detector is installed to control the device. Microcomputer 16 and pulse controller 2 for
According to 1, when there is a difference between the pressure or temperature detected by the pressure or temperature detector and the predetermined pressure or temperature,
It is also possible to employ a method of controlling the opening of the control valve 12 to a predetermined opening corresponding to the difference so that the refrigerant temperature after the pressure reduction by the electronic proportional control valve 12 becomes the set temperature.

[0019]

As described above, according to the present invention, in the first or second aspect of the invention, the condensing pressure of the refrigerant changes due to the change of the ambient environment temperature and accordingly the temperature of the cooling air or the cooling water to the condenser. Even in this case, the refrigerant evaporation temperature in the evaporator can be maintained and stabilized at a predetermined temperature without being affected by the influence.

According to the third aspect of the present invention, as the refrigerating apparatus used for the constant temperature / constant humidity apparatus, a refrigerating apparatus capable of lowering the evaporation temperature to a predetermined temperature is provided even when the ambient environmental temperature rises. It is possible to bring a predetermined minimum temperature in the space area covered with the heat insulating layer of the humidity controller.

According to the invention of claim 4, the pressure of the refrigerant after being decompressed by the decompression means is controlled so as to become a predetermined pressure. Therefore, the temperature of the refrigerant after decompression is brought to a predetermined temperature corresponding to this pressure. Can be maintained.

In the invention of claim 5 or 6, when there is a difference between the pressure or temperature detected by the condensing pressure detecting means, the condensing temperature detecting means or the ambient temperature detecting means and the predetermined pressure or the predetermined temperature by the control means. Since the opening of the control valve is controlled to a predetermined opening corresponding to the difference so that the temperature of the refrigerant after being decompressed by the decompression means becomes a predetermined temperature, it becomes an indirect control but the refrigerant The evaporation temperature can be set to a predetermined temperature.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a thermostatic / humidity device according to an embodiment.

FIG. 2 is a block diagram showing a control system of the constant temperature / constant humidity apparatus.

FIG. 3 is a flow chart of opening control of an electronic proportional control valve of the refrigeration system of the constant temperature / humidity control system.

FIG. 4 is a curve diagram showing the states of changes in condensation temperature, evaporation temperature and test chamber temperature with respect to ambient temperature.

[Explanation of symbols]

 1 heat insulation layer 2 test chamber (in the space area surrounded by heat insulation layer) 9 compressor 10 condenser 12 electronic proportional control valve (variable opening type control valve) 13 evaporator 15 evaporation temperature sensor (temperature detection means) 16 Device Control Microcomputer (Control Means) 21 Pulse Controller (Control Means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication location G01N 25/00 Q 8310-2J P 8310-2J L 8310-2J (72) Inventor Hiroshi Hatta Shizuoka Prefecture 390 Muramatsu, Shimizu City Hitachi, Ltd. Shimizu Plant (72) Inventor Masashi Shimizu 390 Muramatsu, Shimizu City Shizuoka Prefecture Hitachi Ltd. Shimizu Plant

Claims (6)

[Claims] 1. A refrigerant is compressed by a compressor and led to a condenser, cooled and condensed by a cooling medium, condensed, decompressed by a pressure reducing means and led to an evaporator, heated by a heating medium and evaporated again. In the refrigerating apparatus leading to the compressor, the pressure reducing means is a variable opening type control valve, and the temperature detecting means for detecting the temperature of the refrigerant after being pressure-reduced by the pressure reducing means, and the temperature detecting means are used for detection. And a control means for controlling the opening of the control valve so that the temperature becomes a predetermined temperature. 2. The refrigerating apparatus according to claim 1, wherein a control system of the control valve by the control means is any one of proportional control, proportional / integral control, and proportional / integral / differential control. 3. A constant temperature / humidity device for cooling a space area covered with a heat insulating layer with a refrigerating device to maintain a constant temperature and humidity, wherein the refrigerating device is the refrigerating device according to claim 1 or 2. A constant temperature / humidity device characterized by being a device. 4. A pressure detecting means for detecting the pressure of the refrigerant after depressurizing by the depressurizing means is provided in place of the temperature detecting means, and the control means sets the pressure detected by the pressure detecting means to a predetermined pressure. The refrigerating apparatus or the constant temperature / humidity apparatus according to claim 1, wherein the opening degree of the control valve is controlled so as to achieve the above. 5. Condensing pressure detecting means or condensing temperature detecting means for detecting the pressure or temperature of the refrigerant condensed in the condenser is provided in place of the temperature detecting means, and the control means is
When there is a difference between the pressure or temperature detected by the condensing pressure detecting means or the condensing temperature detecting means and a predetermined condensing pressure or condensing temperature, the temperature of the refrigerant after being decompressed by the decompressing means becomes a predetermined temperature. 4. The refrigerating apparatus or the constant temperature / humidity apparatus according to claim 1, wherein the opening degree of the control valve is controlled to a predetermined opening degree corresponding to the difference. 6. An ambient temperature detecting means for detecting the ambient temperature of the refrigerating apparatus is provided in place of the temperature detecting means, and the control means controls the difference between the temperature detected by the ambient temperature detecting means and a predetermined ambient temperature. When there is, characterized in that the opening of the control valve is controlled to a predetermined opening corresponding to the difference so that the temperature of the refrigerant after being decompressed by the decompression means becomes a predetermined temperature. The refrigerating apparatus or constant temperature / humidity apparatus according to claim 1.