JPH0315942Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention creates a sealed space below room temperature,
The present invention relates to an environmental testing device that can adjust the humidity of this space to a desired level without using a humidifier.

Prior Art As shown in FIG. 3, this type of conventional environmental test device is designed to connect an environment test device 2 covered with a casing 1 made of a heat insulating material to a test chamber 6 via a partition plate 4 with constant-temperature and constant-humidity air. A compressor 10 is installed in the constant temperature and humidity air supply chamber 8.
The evaporator 16 of the refrigeration cycle is cyclically connected to the condenser 12, expansion valve 14, evaporator 16, and accumulator 18, an electric heater 20, a blower 22 for air circulation, and a humidifier 24 for forced humidification. A humidity sensor 30 is installed in which the electric heater 20 is connected to a temperature control device 28 that adjusts the power supply based on the detected temperature from a temperature sensor 26 installed in the test chamber 6, and a humidifier 24 is installed in the test chamber 6. Some devices are known that are configured to be connected to a humidity control device 32 that adjusts power supply based on detected humidity.

In the conventional device with the above configuration, the humidifier 2
After the air humidified in step 4 is cooled by an evaporator 16, the air is heated to a predetermined temperature by an electric heater 20.

The adjusted air is then blown into the test chamber 6 by an air circulation blower 22 to maintain the test chamber 6 at a set temperature.

Humidity control was performed by controlling the electric power supplied to the humidifier 24 with a control device 32 based on the detected humidity from a humidity sensor 30 installed in the test chamber 6.

Problems that the invention attempts to solve However, with such conventional environmental test equipment,
Since the humidifier is configured to perform forced humidification as a humidification means, frost tends to adhere to the evaporator that cools the air in low humidity ranges, blocking the air passage of the evaporator and disrupting the refrigeration cycle. There is an inconvenience that the cooling efficiency decreases.

Furthermore, in order to remove the frost attached to the evaporator,
It has the disadvantage that it must be defrosted frequently, making it unsuitable for continuous environmental testing.

SUMMARY OF THE INVENTION In view of the drawbacks of the prior art, it is an object of the present invention to provide an apparatus that can maintain the inside of an environmental testing apparatus at a predetermined temperature and humidity without a humidifier.

Means to Solve the Problems In other words, the present invention consists of a refrigeration cycle that is cyclically connected to a compressor, a condenser, an expansion valve, an evaporator, and an evaporation pressure regulating valve within an environmental test device covered with a casing made of a heat insulating material. In a device arranged with an evaporator, an electric heater, and an air blower, a humidity sensor is included in the environmental test device, and a control device that instructs adjustment of the opening degree of the evaporation pressure regulating valve based on the detected humidity from the humidity sensor. This objective is achieved by an environmental test device equipped with a humidity control mechanism consisting of a drive circuit that adjusts the opening degree of the evaporation pressure regulating valve based on instructions from the control device.

Function: In the apparatus according to the present invention, the refrigeration cycle and electric heater are operated to first bring the inside of the test chamber to a predetermined temperature.

Next, while detecting the humidity in the test room via the temperature sensor, the humidity control device adjusts the opening degree of the evaporation pressure regulating valve, and lowers the evaporation temperature of the evaporator when the humidity in the test room is higher than the set humidity. The drive circuit operates to widen the opening of the evaporation pressure adjustment valve, and to narrow the opening of the evaporation pressure adjustment valve to increase the evaporation temperature of the evaporator when the humidity in the test room is lower than the set humidity. .

When the evaporation temperature of the evaporator becomes low, the temperature sensor detects the temperature in the test chamber, and the temperature control device increases the power supply to the electric heater, and conversely, when the evaporation temperature of the evaporator increases, the temperature control device detects the temperature in the test chamber. Reduce power supply to heater.

As described above, the inside of the environmental test apparatus is set to a predetermined temperature and humidity under the control of the temperature control device and the humidity control device.

Embodiment The present invention will be explained in detail below according to an embodiment shown in the drawings.

40 is an environmental test device covered with a casing 42 made of a heat insulating material, and the inside of the environmental test device 40 is divided by a partition plate 44 into a test chamber 46 and a constant temperature and constant humidity air supply chamber 48.

Inside the divided constant temperature and constant humidity air supply chamber 48, there are a compressor 50, a condenser 52, an expansion valve 54, an evaporator 56,
An evaporation pressure regulating valve 58, an evaporator 56 of a refrigeration cycle connected for circulation to an accumulator 60, an electric heater 62, and a circulation blower 64 are installed.

A humidity sensor 66 and a temperature sensor 67 are installed in the test chamber 46.

The humidity sensor 66 is connected to a humidity control device 68, and the control device 68 instructs the drive circuit 70 to lower the evaporation pressure when the humidity in the test chamber 46 is high based on the set humidity. The drive circuit 70 increases the evaporation pressure when it is low.
It shows fat.

The drive circuit 70 receives power from an AC power source and operates to adjust the opening degree of the evaporation pressure regulating valve 58.

In this embodiment, the drive circuit 70 is configured not to operate at the beginning of the setting change, but to adjust the evaporation pressure from the time the set temperature is adjusted.

The temperature sensor 67 is connected to a temperature control device 82, and the temperature control device 72 instructs to weaken the power supply to the electric heater 62 when the temperature in the test chamber 46 is high based on the set temperature. When the temperature inside the chamber 46 is low, the electric heater 62
Instruct the power supply to be increased.

A power supply circuit 74 supplies predetermined power to the electric heater 72 according to instructions from the temperature control device 72 .

76 is a bypass pipe that short-circuits the refrigerant inlet of the evaporator 56 and the refrigerant inlet of the accumulator 60;
The bypass pipe 76 is provided with a bypass pipe 76 to prevent the vicinity of the refrigerant outlet of the evaporation pressure regulating valve 58 from becoming vacuum pressure.
A solenoid valve 78 that opens and closes 6 is connected.

Note that 80 is a humidifier that receives power from the power supply circuit 82 and evaporates water in the water tank.

The humidifier 80 is used only when the absolute humidity in the environmental test chamber is extremely low and is outside the general humidification range where it is impossible to increase the absolute humidity in the test chamber 46 using only the moisture in the room.

In this case, instructions from the humidity control device 68 are switched by a switch 84.

In the environmental testing apparatus according to the present invention having the above-described configuration, each component is controlled by a timer chart as shown in FIG. 2 to maintain a predetermined temperature and humidity.

From state A (temperature 20℃, humidity 60%RH) to D
(temperature 10℃, humidity 10% RH), the test chamber is cooled with the evaporation pressure regulating valve 58 open at 100%, and the evaporator is set to a dew point temperature of 10℃ and humidity 10% or less. lower the temperature.

Then, the inside of the test chamber 46 is gradually cooled down to the set temperature of 10° C. against the heating of the electric heater 62 (state B).

Next, after the temperature has dropped to the set temperature, the drive circuit 7
0 operates to control the humidity in the test chamber to 10% (C state).

As a result, frost builds up on the evaporator and its surroundings.
The humidity gradually decreases to the set 10% RH.

From state D (temperature 10℃, humidity 10%RH) to G
When setting the conditions (temperature 10° C., humidity 50% RH), the test chamber is cooled with the evaporation pressure regulating valve 58 kept at 100% opening.

Then, the inside of the test chamber 46 is gradually cooled down to the set temperature of 0° C. against the heating of the electric heater 62 (state E).

Drive circuit 70 according to instructions from the next control device.
In order to increase the evaporation pressure by narrowing the opening degree of the evaporation pressure regulating valve 58, the frost that had been attached to the fins of the evaporator begins to melt and evaporate, so that the humidity gradually increases (state F).

As a result, the absolute humidity in the air increases, so the relative humidity also increases.

When the relative humidity reaches 50% RH, the humidity sensor detects this state, and the drive circuit 70 controls the evaporation pressure to maintain the relative humidity at 50% RH.

From the state of G (temperature 0℃, humidity 50%RH) to J
(temperature -50°C, humidity 90% RH), the test chamber is cooled with the evaporation pressure regulating valve 58 kept at 100% opening.

Then, the inside of the test chamber 46 is gradually cooled down to the set temperature of -5° C. (H state) against the heating of the electric heater 62.

The relative humidity in that state is higher than in the G state.

Next, the drive circuit 70 according to instructions from the control device
In order to increase the evaporation pressure by narrowing the opening degree of the evaporation pressure regulating valve 58, the frost that had been attached to the fins of the evaporator begins to melt and evaporate, so that the humidity gradually increases (state I). At this time, the indoor temperature also rises somewhat.

When the humidity becomes higher than the set humidity, the drive circuit 70 is activated to lower the evaporation pressure.

The evaporation temperature then decreases, and the humidity and temperature return to the set values.

From J condition (temperature 0℃, humidity 90%RH)
When setting the test chamber to the following conditions (temperature: 9° C., humidity: 90% RH), the electric heater heats the test chamber with the evaporation pressure regulating valve 58 kept at 100% opening.

Then, the temperature in the test chamber 46 reaches the set temperature, although the humidity in the room is lower than in the state of J (K
situation).

Next, the drive circuit 70 operates to narrow the opening degree of the evaporation pressure regulating valve 58, raise the evaporation temperature, and completely melt the frost attached to the fins of the evaporator 56.
Evaporates and increases relative humidity (L state).

As a result, the absolute humidity will be in the same state as in A at our laboratory.

After the humidity reaches the set 90% RH, the opening degree of the evaporation pressure regulating valve 58 expands to stabilize the humidity (M state).

After stabilization, the temperature sensor 67 and humidity sensor 6 are operated to maintain the set temperature and set humidity.
6, the power supply to the electric heater 62 and the evaporation pressure are finely adjusted.

As described above, the inside of the environmental test apparatus is maintained at a predetermined temperature and humidity.
If the evaporation pressure regulating valve 58 is tightened too much when increasing the evaporation pressure of the refrigerant, the vicinity of the refrigerant outlet will be in a vacuum state, which may put a load on the compressor 50.

Therefore, in the refrigeration cycle of this embodiment, the solenoid valve 7
8 is opened to bypass the refrigerant from the vicinity of the refrigerant inlet of the evaporator 56.

Furthermore, in the environmental test apparatus 40 of this embodiment, there is a limit to the adjustment of relative humidity depending on the initial absolute humidity state in the test chamber 46.

Therefore, in this embodiment, power is supplied to the forced humidifier only in such cases to increase the absolute humidity.

Effects As described above, the environmental test device according to the present invention allows the test room to be controlled at a specified temperature by controlling the electric heater using the temperature sensor and controlling the evaporator using the temperature sensor, without using a forced humidifier in the low humidity range. Temperature and humidity can be controlled.

Furthermore, since a forced humidifier is not used in principle, frost is less likely to form on the evaporator than with conventional devices.
Since there is no need for defrosting, continuous environmental tests can be performed.

In addition, a humidity sensor detects the humidity in the test chamber, and feedback control is performed in which the evaporator is operated based on the detected humidity, making it possible to precisely control the humidity in the room.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the device according to the present invention, FIG. 1 is a schematic diagram of the device, FIG. 2 is a time chart showing the operation of each part of the device, and FIG.
The figure is a schematic diagram of a device showing the prior art. 1,42...Casing, 2,40...Environmental test device, 4,44...Partition plate, 6,46...Test chamber, 8,48...Constant temperature and humidity air supply chamber, 10,5
0...Compressor, 12,52...Condenser, 14,5
4...Expansion valve, 16,56...Evaporator, 18,6
0...Accumulator, 20,62...Electric heater, 22,64...Blower, 24,80...Humidifier, 26,67...Temperature sensor, 28,72
... Temperature control device, 30, 66 ... Temperature sensor, 32, 68 ... Humidity control device, 58 ... Evaporation pressure regulating valve, 70 ... Drive circuit, 74 ... Power supply circuit, 76 ... Bypass pipe, 78...Solenoid valve,
82...Power supply circuit, 84...Switch.

Claims (1)

[Scope of utility model registration request] The compressor, condenser, expansion valve, evaporator, evaporation pressure regulating valve, refrigeration cycle evaporator, electric heater, and air blower were placed in an environmental test device covered with a casing made of heat insulating material. The apparatus is characterized in that the control device is configured to adjust the opening degree of the evaporation pressure regulating valve so as to achieve a set humidity based on a detection signal from a humidity sensor installed in the environmental test device. Environmental test equipment.