JPH0510584B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Industrial Application Field The present invention relates to a storage for storing and cooling foods, etc., and more specifically, a control device for a storage that prevents the food from drying out by increasing the humidity in the storage room. Regarding.

(B) Conventional technology Conventionally, in this type of storage, the electric compressor included in the cooling device that cools the inside of the storage room is operated by setting upper and lower temperature limits above and below the target storage room temperature, and then operating the electric compressor at the upper limit temperature. The compressor is started and stopped at the lower limit temperature (so-called ON-OFF control) to bring the temperature in the storage chamber closer to the target temperature on average. Due to the cooling by the cooling device, water vapor in the air within the storage room adheres to the cooler included in the cooling device and becomes dew or frost, so the humidity inside the storage room is usually very low.
As a result, moisture evaporates from the food stored in the storage room, resulting in drying and deterioration of quality. In order to prevent such drawbacks, the conventional structure is such that water vapor is introduced into the storage chamber to maintain a high humidity inside the storage chamber. One example is Utility Model Application No. 56-38288.

By the way, in this type of storage, if the difference between the above-mentioned upper limit temperature and lower limit temperature, that is, the differential, is increased, the temperature fluctuation of the stored food will also increase, resulting in significant quality deterioration, so the smaller the differential, the better. Food quality control is good, but if the differential is made too small, the electric compressor will start and stop frequently, causing significant damage to the electric compressor parts and increasing power consumption. will occur. Particularly in the case where water vapor is introduced into the storage chamber as described above, the increase in the load on the storage chamber due to the water vapor causes the temperature to rise faster while the electric compressor is stopped, resulting in the electric compressor having to be started and stopped more frequently.

In order to solve this drawback, a method may be considered in which, for example, the cooling device is always in operation and the operation of, for example, a blower that introduces water vapor into the storage chamber is controlled to control the temperature inside the storage chamber. This system operates a blower to introduce water vapor into the storage room when the temperature inside the storage room falls below a target value. This increases the load and temperature within the storage chamber. The operation of this blower is appropriately controlled to control the temperature while maintaining the humidity in the storage chamber at a high level, but this method has the advantage that the above-mentioned differential can be reduced compared to controlling an electric compressor.

(c) Problems to be Solved by the Invention However, according to such a configuration, since the cooling device is operated continuously, the humidity inside the storage room changes depending on the environment around the storage room. That is, in a situation where the ambient temperature is low, such as in winter, the temperature inside the storage room tends to drop, so a large amount of water vapor is introduced in an attempt to raise the temperature, resulting in an excessive rise in humidity. On the other hand, when the ambient temperature is high, such as during summer, the temperature inside the storage room tends to rise, causing the problem that water vapor is no longer introduced and the humidity becomes too low.

(d) Means for Solving the Problems In order to solve the problems, the present invention has a water vapor supply device that supplies water vapor into the storage chamber 2 of the storage warehouse 1, depending on the temperature inside the chamber 2. The rotation speed of the electric compressors 13 and 14 of the cooling device 3, which constantly cools the inside of the room 2, is controlled according to the humidity inside the room 2, and the humidity inside the room 2 is adjusted to the desired temperature. 2 is controlled.

(E) Effect According to the present invention, the inside of the storage room is maintained at a desired temperature by continuously cooling the storage room with the cooling device and supplying water vapor, thereby balancing the temperature rise due to an increase in the indoor load, and also controlling the room temperature. You can also set the differential to a smaller value.

In addition, the rotation speed of the electric compressor of the cooling device is adjusted depending on the humidity in the storage room.When the humidity is high, the rotation speed is lowered to suppress the introduction of water vapor, and when the humidity is low, the rotation speed is increased to prevent the introduction of water vapor. It is possible to promote

(f) Examples Examples will be explained with reference to the drawings. Figures 4 and 5
In the figure, reference numeral 1 is an example of an ice-warmed warehouse in which the inside of the storage room 2 is kept cooled at an ice temperature of approximately -1°C. The insulating box 6 is constructed by loading urethane or glass wool, or an insulating block with a vacuum inside, or by assembling insulating panels into a box shape. It is called room 2. In the embodiment, the heat insulating box body 6 is open to the front, but it may be open to the top, and the opening is closed by a heat insulating door (not shown) so as to be openable and closable. In addition, freezing temperature here refers to the temperature range below freezing before meat and fish freezes, and this temperature is usually between 0°C and about -2°C.
is within the range of

FIG. 4 is a partially cutaway perspective view of the storage 1, and FIG. 5 is a partially cutaway front view of the same. Cooling units 7 and 8, each having an independent refrigerant circuit, constituting the cooling device 3 are provided on the ceiling of the storage 1 and are fixed to heat insulating mounting boards 9 and 10, respectively. A unit cover 11 is provided on the ceiling of the storage chamber 2, and a cooling chamber 12 partitioned from the storage chamber 2 is formed between this and the mounting boards 9 and 10. On the outside of each of the mounting boards 9 and 10 are electric compressors 13 and 14 that constitute the cooling units 7 and 8, respectively.
and condensers 15 and 16, and coolers 17 and 18 are respectively attached to the cooling chamber 12 side.
A duct member 21 is provided at approximately the center of the back surface of the storage chamber 2, which extends vertically, has a discharge duct 19 inside, and has a plurality of discharge ports 20 on both sides that communicate the storage chamber 2 and the discharge duct 19. This discharge duct 19
communicates with the cooling chamber 12 at the top. Approximately in the center of the unit cover 11 are the upper part of the storage chamber 2 and the cooling chamber 1.
2 is formed, and suction fans 23 and 24 are provided at the front lower part of each of the coolers 17 and 18 in the cooling chamber 12,
Furthermore, a discharge fan 25 is provided at the upper end of the discharge duct 19. The suction fans 23 and 24 suck air in the storage chamber 2 from the suction section 22 and supply the air to the cooler 1, respectively.
7, 18, and the air is sent to the cooler 17 or 18.
After being cooled by the discharge fan 25, it is discharged into the discharge duct 19 and discharged from the discharge port 20 into the storage chamber 2, where it circulates as shown by the solid line arrow in the figure to cool the storage chamber 2.

A water storage tank 30 is provided at the bottom outside of the heat insulating box 6. This water tank 30 communicates with the outside air at a suitable location above the water surface. Water is supplied to this water tank 30 by automatic water supply using a water level sensor and pump, or by manual water supply, and furthermore, the water in the water tank 30 is constantly heated to about 50°C by a heater 31. Therefore, water vapor is constantly generated from the water storage tank 30. This water vapor is drawn up by a humidifying fan 33 provided at the upper end of a humidifying duct 32 that extends upward on the outer surface of the back wall of the insulating box 6, rises, is sent into the discharge duct 19 from the discharge port 34, and is sent upward. It is discharged into the storage chamber 2 from the discharge port 20 on the flow of cold air from the air, humidifying the storage chamber 2, and as a result, the cooler 17 or 18
It forms frost and adheres to the surface. The water tank 30, the heater 31, the humidifying duct 32, and the humidifying fan 33 constitute a water vapor supply device.

FIG. 1 shows in block diagram form a control system 36 of the present invention. 37 is a temperature setting device that sets the temperature inside the storage room 2, and here the temperature inside the storage room 2 is set from 0°C to -2°C.
The output is inputted to the micro CPU 39 via the A/D converter 38,
For example, the upper limit temperature (TH) of the storage room 2 is set to 0°C, and the lower limit temperature (TL) is set to -2°C. 40 is a humidity setting device for setting the humidity in the storage room 2, and its output is sent to the micro CPU 3 via the A/D converter 41.
Output to 9. Also, here, the humidity (HS) in the storage room (2) is set to be about 90%, that is, high humidity at a temperature of -1°C. A temperature sensor 42 detects the temperature inside the storage chamber 2, and its output is input to the micro CPU 39 via an A/D converter 43. Also, 44
is a humidity sensor that detects the humidity in storage room 2,
The output is similarly input to the micro CPU 39 via the A/D converter 45.

The micro CPU 39 generates an output from an output terminal 47 based on temperature information from the temperature setting device 37 and the temperature sensor 42, and controls the operation of the humidifying fan 33 by a driver 49 via a D/A converter 48. Further, the micro CPU 39 generates an output from an output terminal 50 based on the humidity information from the humidity setting device 40 and the humidity sensor 44, and converts it into an analog voltage using a D/A converter 51. 52 is an inverter circuit, which generates a three-phase AC output with a frequency approximately proportional to the output of the D/A converter 51, and outputs a three-phase AC output through a switching means 53 to the electric compressor 13 or 8 of the cooling unit 7 or 8 of the cooling device 3. 14. The electric compressors 13 and 14 are so-called tally type electric compressors, and their motors are constituted by, for example, three-phase synchronous motors, and the rotational speed changes approximately in proportion to the output frequency of the inverter circuit 52.

An output is generated at the output terminal 54 of the micro CPU 39 every two hours, and the switching means 53 is operated to alternately input the output of the inverter circuit 52 to the electric compressor 13 or 14. That is, the electric compressor 13,1
4, when one is in operation, the other is stopped, and this is switched every two hours, and the cooler of the cooling unit with the stopped electric compressor is switched to the defrosting heater 55 or 56. It is then defrosted. Since the inside of the storage room 2 is always maintained at high humidity, frost buildup on the cooler 17 or 18 is significant, but the cooler is constantly defrosted, so that the cooling efficiency can always be maintained at a good level.

FIG. 2 shows an outline of the flowchart of the temperature control software for the micro CPU 39, and FIG. 3 shows an outline of the flowchart of the humidity control software. Temperature sensor 4 at step (S ₁ )
2, the current temperature (TP) in the storage room 2, that is, temperature information is read, and in step (S ₂ ) it is determined whether or not it is above the upper limit temperature (TH) of 0°C, and if not, in step (S ₃ ). The lower limit temperature (TL) is −2
Determine whether the temperature is below ℃. If the temperature (TP) is below the lower limit temperature (TL) in step (S ₃ ), the process proceeds to step (S ₄ ), generates an output from the output terminal 47, operates the humidifying fan 33, and cools the inside of the storage chamber 2. Introduce water vapor. The temperature of the storage chamber 2 rises due to the introduction of water vapor, and when (TL) < (TP) < (TH), the process proceeds from step (S ₃ ) to step (S ₅ ), but the storage chamber 2 Since the temperature (TO) of chamber 2 was below (TL), proceed to step (S ₄ ).
The humidifying fan 33 continues to operate. When the temperature further increases and (TP) exceeds (TH), the process proceeds from step (S ₁ ) to step (S ₆ ) and the humidifying fan 33 is stopped. The temperature in storage room 2 drops again as the introduction of water vapor stops, but (TL)
Even if ＜(TP)＜(TH), the previous temperature (TO)
is greater than or equal to (TH), proceeding from step (S ₅ ) to step (S ₆ ) and continuing to stop the humidifying fan 33.
When (TP) becomes less than (TL), step again (S ₃ )
The process then proceeds to (S ₄ ) and the humidifying fan 33 is operated. Among the above operations, temperature sampling is performed when the temperature in the storage room crosses the upper limit temperature (TH) or lower limit temperature (TL), and after processing, the current temperature is used instead of the previous temperature (TO). Temperature (TP)
is written and memorized. By this operation, the inside of the storage chamber 2 is maintained at an average temperature of -1°C between 0°C and -2°C. Furthermore, since it is the humidifying fan 33 that is stopped, the difference between the temperatures (TH) and (TL), that is, the differential, can be reduced, and temperature fluctuations can be reduced.

Next, in the flowchart for humidity control shown in FIG. 3, _the humidity sensor 44 is
The current humidity (HP) in the storage room 2, that is, humidity information is read, and in step ( _S11 ) it is determined whether the humidity is lower than the set humidity (HS), that is, 90%, and if it is lower, the process proceeds to step ( _S12 ). , the micro CPU 39 changes the output from the output terminal 50 to increase the output frequency of the inverter circuit 52. As a result, the rotational speed of the electric compressor 13 or 14 increases, and the cooling capacity of the cooling unit 7 or 8 increases. Steps (S ₃ ) to (S ₄ ) or (S ₅ )
Since (S ₄ ) is executed to operate the humidifying fan 33, the humidity in the storage chamber 2 increases. If the result in step (S ₁₁ ) is negative, the process proceeds to step (S ₁₃ ), and if (HP) is higher than the set humidity (HS), the process proceeds to step (S ₁₄ ), where the micro CPU 39 changes the output from the output terminal 50. and inverter circuit 5
Execute the operation to lower the output frequency of step 2. As a result, the rotational speed of the electric compressor 13 or 14 decreases, and the cooling capacity of the cooling unit 7 or 8 decreases, so the micro CPU 39 stops the humidifying fan 33 in an attempt to lower the temperature inside the storage chamber 2. It becomes like this. This reduces the humidity within the storage chamber 2. If the result in step (S ₁₃ ) is negative, it means that (HP) is equal to (HS), so the process advances to step (S ₁₅ ) and the micro CPU 39 maintains the rotational speed of the electric compressor 13 or 14.

By the above operation, the humidity (HP) in storage room 2
converges to 90%, but the humidity information is sampled every 15 seconds, for example, in the flowchart of FIG. 3, and the frequency adjustment operation is executed. In addition, the frequency change operation by the micro CPU 39 calculates a frequency correction factor proportional to the deviation between the set humidity (HS) and the current humidity (HP), and for example, changes the rotation frequency of the electric compressor 13 or 14 from 30Hz to
Configured to run in the 120Hz range.

By repeating the operations of the steam supply device and the cooling unit, the temperature inside the storage room 2 is maintained at -1°C on average, and the temperature around the storage room 1 is kept at -1°C. The inside of storage room 2 is always kept at a high humidity of 90%. Furthermore, since the heat capacity of the air within the storage chamber 2 is increased due to such high humidity, the rate of decrease in temperature is also slow, and as a result, the temperature change within the storage chamber 2 becomes very gradual. Therefore, the food stored in the storage chamber 2 does not freeze, thereby preventing tissue destruction, and since the temperature is below freezing, the growth of bacteria inside is also suppressed. Furthermore, since the food is stored in a high-humidity environment, there is less water evaporation from the surface of the food, which prevents the food from drying out. Furthermore, since the storage temperature changes gradually and becomes almost constant temperature, deterioration of food quality due to temperature fluctuations is also suppressed. As a result, the shelf life of food from rigor mortis to protein decomposition and spoilage can be extended over a long period of time (in experiments, 20
About a day. Here, when not according to the present invention, it is usually 4 days. ) and the storage period will be extended. Here, the above-mentioned switching interval of the cooling units 7 and 8 (2 hours in the embodiment) is determined taking into consideration the high humidity inside the storage room 2, but it is also determined by controlling the rotation speed. Compared to normal ON-OFF control, etc., the number of times the electric compressors 13 and 14 are started and stopped is much smaller, so damage to component parts due to aging is also reduced. Also, this allows the device 3
It is also possible to reduce the differential set by 7 (2 degrees Celsius between 0 degrees Celsius and -2 degrees Celsius in the example), and the storage room 2 temperature can be brought closer to constant temperature, further improving the shelf life of food. Becomes good. Furthermore, the time delay due to the heat capacity of the temperature sensor 42 is
This is corrected by slowing down the temperature change due to the increase in heat capacity of the air in the storage room 2, so the difference between the temperature sensed by the temperature sensor 42 and the actual temperature becomes smaller, improving temperature control performance. , and adjustment of circuit element setting values is also facilitated.

In the embodiments, the present invention is applied to a storage room that is cooled to an ice temperature, but the present invention is not limited thereto, and may be used to cool a storage room to a general refrigeration temperature or freezing temperature.

(G) Effects of the Invention According to the present invention, the cooling unit included in the cooling device is not normally subjected to so-called ON-OFF control based on the temperature in the storage room, so aging deterioration of component parts is suppressed, resulting in improved durability. do. In addition, this makes it possible to reduce the range of the upper and lower temperature limits set in the storage room, that is, the differential.
Maintaining a high level of humidity slows down temperature fluctuations, making it possible to bring the surrounding environment of stored food closer to a constant temperature, further improving the quality retention ability of food and extending its shelf life. can. Furthermore, since the evaporation of water from the surface of the food is also suppressed, drying is suppressed and the shelf life of the food is further improved.

Furthermore, according to the present invention, the humidity inside the storage room is detected and the humidity inside the storage room is reliably maintained at a substantially constant level.
This prevents ice build-up in the storage room due to excessive humidification, and conversely, prevents food from drying out due to insufficient humidification, allowing for stable food storage.

[Brief explanation of the drawing]

Each figure shows an embodiment of the present invention, FIG. 1 is a block diagram of a control device, and FIGS. 2 and 3 are a microcontroller.
A flowchart showing the software of the CPU, FIG. 4 is a partially cutaway perspective view of the storage, and FIG. 5 is a partially cutaway front view of the same. 1...Storage, 3...Cooling device, 13, 14...
...Electric compressor, 33... Humidifying fan, 39...
Micro CPU, 42...Temperature sensor, 44...
...Humidity sensor.

Claims (1)

[Claims] 1. A cooling device that constantly cools the interior of the storage chamber, a steam supply device that supplies steam into the storage chamber, and a temperature control device that controls the steam supply device to maintain the interior of the storage chamber at a desired temperature based on the temperature inside the storage chamber. and a humidity control device that detects the humidity in the storage room and adjusts the rotation speed of an electric compressor of the cooling device so that the humidity becomes a desired humidity.