JPH04240373A - Temperature and humidity control device for refrigerator - Google Patents

Abstract

PURPOSE:To refrigerate food stuffs in a high degree of freshness by controlling a temperature and a humidity in a refrigerator independently. CONSTITUTION:The exciting period of time of a solenoid valve 21 is controlled in accordance with the temperature of the inside air of a refrigerator main body 2 and the temperature of outside air to regulate the flow rate of refrigerant passing through a refrigerant evaporator 17 whereby the refrigerating capacity of a refrigerating cycle 3 is controlled and the temperature of inside air is controlled. An inside fan 5 is controlled in accordance with the humidity of the inside air and the surface temperature of the refrigerant evaporator 17 to regulate the amount of ventilating air for the refrigerant evaporator 17 whereby the performance of the refrigerant evaporator 17 is controlled and the humidity of the inside air is controlled.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a temperature/humidity control device for a refrigerator that independently controls the temperature and humidity of the air inside the refrigerator. This makes it possible to refrigerate foods with high freshness.

0002

2. Description of the Related Art In a refrigerator that stores and refrigerates food in a refrigeration chamber, it is necessary to maintain the inside of the refrigeration chamber at a low temperature and high humidity in order to maintain the freshness of the food. In order to keep foods even more fresh, it is desirable to set the temperature and humidity in the refrigerator compartment to the optimal storage temperature and humidity range for each food.

[0003] Here, the humidity of the air inside the refrigerator is normally reduced by dehumidification when the refrigerant compressor is operated at its normal capacity, and the moisture in the refrigerator adheres to the refrigerant evaporator that cools the air inside the refrigerator with the inflowing refrigerant. be done. For this reason, the temperature of the air inside the refrigerator is, for example, 4℃.
As a result, the humidity of the air inside the refrigerator decreases to about 60%. Also, when the refrigerant compressor stops operating,
As the frost adhering to the refrigerant evaporator melts and evaporates due to the forced air flow from the internal blower, moisture is returned to the refrigerator compartment, causing a rapid increase in the humidity of the air inside the refrigerator. When the temperature of the air inside the refrigerator rises to, for example, 10° C., the humidity of the air inside the refrigerator rises to about 90%.

[0004] Therefore, the humidity of the air inside the refrigerator decreases when the refrigerant compressor is operated at its normal capacity, and the humidity of the air inside the refrigerator rapidly increases when the refrigerant compressor stops operating. A temperature/humidity control device for a refrigerator (prior art: 1983) is capable of stabilizing the humidity of the air inside the refrigerator by controlling the operation and stoppage of the refrigerant compressor.
-30716, etc.) have been proposed.

[0005]

However, in the prior art, when the operation of the refrigerant compressor is stopped, the humidity of the air inside the refrigerator increases and the inside of the refrigerator compartment is kept at high humidity, but the temperature of the air inside the refrigerator increases. There was a problem in that the temperature of the air inside the refrigerator could not be maintained at the set temperature. Furthermore, by controlling the operation and stoppage of the refrigerant compressor, there was also a problem in that the temperature and humidity of the air inside the refrigerator fluctuated considerably. Therefore, it is not possible to set the temperature and humidity in the refrigerator compartment to the optimal storage temperature and humidity range for each food item, resulting in a problem in that the freshness of the food product decreases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a temperature/humidity control device for a refrigerator that is capable of refrigerating food with high freshness by independently controlling the temperature and humidity of the air inside the refrigerator.

[0007]

[Means for Solving the Problems] The present invention includes a refrigerator body that stores food therein, a refrigerant compressor that compresses and discharges refrigerant, and a system that heats the refrigerant discharged from the refrigerant compressor and the air inside the refrigerator. A refrigerant evaporator to be replaced, a refrigerant condenser that exchanges heat between the refrigerant flowing out from the refrigerant evaporator and air outside the refrigerator, and a refrigerant discharged from the refrigerant compressor bypassing the refrigerant evaporator and the refrigerant condenser. A refrigeration cycle having a bypass pipe that returns the refrigerant to the refrigerant compressor, and a flow rate adjustment means that adjusts the flow rate of the refrigerant flowing through the bypass pipe, an internal blower that blows internal air to the refrigerant evaporator, and An internal temperature sensor that detects temperature, an external temperature sensor that detects the temperature of external air, an internal humidity sensor that detects the humidity of internal air, and a surface temperature that detects the surface temperature of the refrigerant evaporator. a sensor, and controls the flow rate adjusting means according to the temperature of the air inside the refrigerator and the temperature of the air outside the refrigerator, and controls the inside blower according to the humidity of the air inside the refrigerator and the surface temperature of the refrigerant evaporator. Adopted technical means with a control circuit to control.

[0008]

[Operation] The present invention utilizes the following two principles. First, it is known that the first principle is that when the temperature of dry air is constant compared to the moist air line, the closer the dew point temperature is to the dry air temperature, the higher the relative humidity is. Here, the dew point temperature is replaced by the surface temperature of the refrigerant evaporator, so by controlling the surface temperature of the refrigerant evaporator, that is, the refrigerant evaporator performance, the humidity of the air inside the refrigerator can be controlled independently of the temperature. is possible.

Next, as a second principle, the temperature of the air inside the refrigerator is determined by the amount of heat entering the refrigerator (the temperature difference between the temperature of the air inside the refrigerator and the temperature of the air outside the refrigerator) and the temperature of the outside air. It is determined by the balance with the refrigerating capacity of the cycle. In other words, the temperature of the air inside the refrigerator can be controlled independently of the humidity by controlling the refrigeration capacity of the refrigeration cycle or by controlling the amount of heat that enters the refrigerator body. However, one possible way to control the refrigeration capacity of the refrigeration cycle is to use an inverter to control the rotation speed of the refrigerant compressor and change the capacity of the refrigerant compressor, but this requires an expensive inverter and is therefore not economical. isn't it. Furthermore, in order to control the amount of heat that enters the refrigerator, it is necessary to change the plate thickness of the refrigerator body, for example, and such a refrigerator cannot be adopted because the structure is complicated and control is difficult.

Therefore, in the present invention, when the temperature of the air inside the refrigerator detected by the temperature sensor inside the refrigerator reaches a preset temperature, the temperature of the air outside the refrigerator detected by the temperature sensor outside the refrigerator and the temperature inside the refrigerator are The amount of heat entering the refrigerator is determined based on the air temperature, and the current refrigerating capacity of the refrigeration cycle is determined from the current flow rate of the refrigerant flowing through the bypass piping. Then, the flow rate of the refrigerant passing through the refrigerant evaporator and the refrigerant condenser is adjusted by adjusting the flow rate of the refrigerant flowing through the bypass pipe according to the current refrigeration capacity of the refrigeration cycle and the amount of heat entering the refrigerator. Therefore, since the amount of refrigerant flowing into the refrigerant evaporator changes, it becomes possible to control the refrigerating capacity of the refrigerating cycle without stopping the operation of the refrigerant compressor. The temperature of the air inside the refrigerator is maintained at, for example, a set temperature by the balance between the refrigerating capacity of the refrigeration cycle and the amount of heat that enters the refrigerator.

[0011] Furthermore, in the present invention, when the humidity of the air inside the refrigerator detected by the humidity sensor reaches a preset set humidity, the temperature is increased according to the surface temperature of the refrigerant evaporator detected by the surface temperature sensor. Controls the internal blower to adjust the amount of air sent to the refrigerant evaporator. Therefore, since the amount of refrigerant flowing into the refrigerant evaporator changes, the surface temperature of the refrigerant evaporator, that is, the refrigerant evaporator performance is controlled. Therefore, the humidity of the air inside the refrigerator is maintained at the set humidity, for example.

0012

According to the present invention, since the temperature and humidity of the air inside the refrigerator can be controlled independently, the inside of the refrigerator main body can be kept at a low temperature and high humidity. As a result, the inside of the refrigerator body can be maintained at the optimal storage temperature and humidity for food, making it possible to refrigerate food with high freshness.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A temperature and humidity control device for a refrigerator according to the present invention will be explained based on an embodiment shown in FIGS. 1 to 5. FIG. 1 is a diagram showing a temperature and humidity control device for a refrigerator.

The refrigerator temperature and humidity control device 1 includes a refrigerator body 2, a refrigeration cycle 3, an external fan 4, an internal fan 5, an internal temperature sensor 6, an internal humidity sensor 7, a surface temperature sensor 8, and an external temperature sensor. A sensor 9 and a control circuit 10 are provided.

The refrigerator main body 2 has a heat insulating box 12 forming a refrigerating chamber 11 in which food is stored and refrigerated.

The refrigeration cycle 3 includes a refrigerant compressor 13, a refrigerant condenser 14, a receiver 15, an expansion valve 16, and a refrigerant evaporator 1.
7, an accumulator 18, a refrigerant pipe 19, a bypass pipe 20, and a solenoid valve 21. refrigerant compressor 13, refrigerant condenser 14, receiver 15, expansion valve 16,
Since the refrigerant evaporator 17 and the accumulator 18 have well-known structures, a description thereof will be omitted. Note that among the components of the refrigeration cycle 3, only the refrigerant evaporator 17 is included in the refrigerator compartment 1 of the refrigerator body 2.
It is located within 1.

The refrigerant pipe 19 includes a refrigerant compressor 13, a refrigerant condenser 14, a receiver 15, an expansion valve 16, and a refrigerant evaporator 17.
and the accumulator 18 are connected in a ring.

The bypass pipe 20 is a pipe for returning the refrigerant discharged from the refrigerant compressor 13 to the refrigerant compressor 13 by bypassing the refrigerant condenser 14, receiver 15, expansion valve 16, and refrigerant evaporator 17. .

The solenoid valve 21 is a flow rate adjusting means of the present invention, and when energized, opens the bypass piping 20, and when energized, closes the bypass piping 20 and closes the bypass piping 20.
Adjust the flow rate of refrigerant flowing through 0.

When the external fan 4 is energized, it rotates and blows external air from outside the refrigerator compartment 11 onto the refrigerant condenser 14 .

[0021] The internal fan 5 changes its rotational speed depending on the current value or voltage value. Further, the internal air blower 5 transfers internal air within the refrigerator compartment 11 to the refrigerant evaporator 17 according to the rotation speed.
Change the amount of air blown (air volume).

The refrigerator temperature sensor 6 is disposed in the refrigerator compartment 11 of the refrigerator body 2, and detects the temperature of the refrigerator air.The temperature sensor 6 converts the detected temperature of the refrigerator air into an electrical quantity and sends it to the control circuit. Send to 10.

The internal humidity sensor 7 is arranged in the refrigerator compartment 11 of the refrigerator main body 2 and detects the humidity of the internal air.The internal humidity sensor 7 converts the detected humidity of the internal air into an electrical quantity and sends it to the control circuit. Send to 10.

The surface temperature sensor 8 is attached to the fin of the refrigerant evaporator 17 and detects the surface temperature of the refrigerant evaporator 17. The surface temperature sensor 8 converts the detected surface temperature of the refrigerant evaporator 17 into an electrical quantity and sends it to the control circuit. Send to 10.

The outside temperature sensor 9 is disposed outside the refrigerator compartment 11 of the refrigerator body 2, and detects the temperature of the outside air. Send to 10.

The control circuit 10 changes the refrigerating capacity of the refrigeration cycle 3 by controlling the energization of the solenoid valve 21 according to the temperature and humidity of the air inside the refrigerator. In addition, the control circuit 10
controls the amount of air blown by the internal blower 5 according to the temperature of the internal air and the surface temperature of the refrigerant evaporator 17.
change the performance of

Next, an example of temperature and humidity control by the control circuit 10 will be explained based on the flowchart of FIG. First, the set temperature and set humidity in the refrigerator compartment 11 are read (step S1). Note that the temperature in the refrigerator compartment 11 is set to 0°C in advance.
The set humidity in the refrigerator compartment 11 is set to 90% in advance. Then, initial settings are made for the refrigerating capacity of the refrigerant compressor 13, the amount of air blown by the external blower 4 and the internal blower 5, etc. (step S2).

Next, the temperature of the air inside the refrigerator is read (step S3), and it is determined whether the temperature of the air inside the refrigerator is within the set temperature range (set temperature ±5° C.) (step S4).
. When the temperature is not within the set temperature range (N), the temperature of the air outside the refrigerator is read (step S5), and the amount of decrease in the refrigerating capacity of the refrigeration cycle 3 is determined from the amount of heat entering the refrigerator (step S6).
.

Then, the bypass on-off ratio of the solenoid valve 21 (T2
/T1) (step S7). Here, T1 is the cycle, and T2 is the energization time of the solenoid valve 21. Then, the electromagnetic valve 21 is energized and controlled according to the obtained bypass on/off ratio (step S8). After that, control in step S3 is performed.

In step S4, when the temperature is within the set temperature range (Y), the humidity of the air inside the refrigerator is read (step S4).
9) It is determined whether or not the humidity of the air inside the refrigerator has risen above the set humidity (step S10). When the humidity of the air inside the refrigerator has risen to the set humidity or higher (Y), control in step S3 is performed.

In step S10, when the humidity has not risen above the set humidity (N), the surface temperature of the refrigerant evaporator 17 is read (step S11), and a target air flow rate to the refrigerant evaporator 17 is calculated (step S12). . Next, the current value or voltage value of the internal fan 5 is controlled so as to reach the target air flow rate (step S13). Then, control in step S9 is performed.

The operation of the refrigerator temperature and humidity control device 1 will be explained based on FIGS. 1, 3 to 6.

As shown in FIG. 3, for example, the current temperature and humidity of the air inside the refrigerator body 2 are 10° C. and 60%.
(Point A), the temperature and humidity of the air inside the refrigerator are set to 0.
℃ and 90% (point B), first, control is performed to lower the temperature of the air inside the refrigerator.

At this time, the temperature ti of the air inside the refrigerator, the refrigerating capacity Q of the refrigeration cycle, and the amount of heat entering the refrigerator qi are as shown in FIG. Here, the refrigerating capacity Q indicates the time of 100% capacity. In addition, the amount of heat intruding into the refrigerator is expressed by the following formula. Formula qi=KF(to-ti)+qfK is the heat transfer rate of the insulation box 12, F is the heat transfer area of the insulation box 12, to is the temperature of the air outside the refrigerator, ti is the temperature of the air inside the refrigerator, qf This is the internal calorific value (the calorific value of the internal blower 5).

As shown in FIG. 4, when the refrigeration cycle 3 is determined, the refrigerating capacity line of the refrigeration cycle 3 is determined, and the insulation box 1
2 and the amount of heat generated inside the refrigerator is determined, the amount of heat that penetrates into the refrigerator is determined. In the case of Fig. 4, when the refrigeration cycle 3 is continuously operated at 100% capacity from the equilibrium point (point C) between the refrigerating capacity of the refrigeration cycle 3 and the amount of heat entering the refrigerator, the temperature of the air inside the refrigerator is -10°C. It shows that.

[0036] With this, the temperature of the air inside the refrigerator can be controlled by lowering the refrigerating capacity. That is, as shown in FIG. 4, when the refrigerating capacity of the refrigeration cycle 3 is 80% capacity, the temperature ti of the air inside the refrigerator reaches 0°C from the equilibrium point (point D) between the refrigerating capacity Q and the amount of heat qi entering the refrigerator. It can be confirmed that this will happen.

Therefore, in this embodiment, the control circuit 1
0 determines the amount of decrease in the refrigerating capacity of the refrigeration cycle 3 from the temperature of the air inside the refrigerator and the temperature of the air outside the refrigerator, and calculates the bypass on-off ratio (T2/T1) of the solenoid valve 21 from the amount of decrease in the refrigerating capacity. The refrigerant is allowed to flow through the bypass pipe 20 by controlling the energization time of the solenoid valve 21 and the interval between energization and de-energization.

Therefore, the amount of refrigerant flowing through the refrigerant condenser 14, refrigerant evaporator 17, and other refrigeration equipment through the refrigerant pipe 19 is reduced, so the amount of refrigerant vaporized in the refrigerant evaporator 17 is also reduced. . Therefore, the refrigerating capacity of the refrigerating cycle 3 changes from 100% capacity to 80% capacity, and the temperature of the air inside the refrigerator drops to 0°C. At this time, since the humidity of the air inside the refrigerator decreases due to a decrease in the refrigerating capacity of the refrigeration cycle 3, control is performed to simultaneously increase the humidity of the air inside the refrigerator.

As shown in FIG. 5, when the dew point temperature changes, the relative humidity also changes. That is, when the dry bulb temperature (temperature of the air inside the refrigerator) and the dew point temperature are 0° C. and −6° C. (point E), the relative humidity is 60%. In addition, the dry bulb temperature (temperature of the air inside the refrigerator) and dew point temperature are 0℃ and -1.2℃ (point F
), the relative humidity is 90%. Here, since the surface temperature of the refrigerant evaporator 17 is considered to be the dew point temperature, the relative humidity can be changed by controlling the surface temperature of the refrigerant evaporator 17, that is, the performance of the refrigerant evaporator 17.

Here, the performance of the refrigerant evaporator 17 is determined by the following equation. Formula qe=WφΔT Here, qe is the heat exchange amount [kcal] of the refrigerant evaporator 17 and is constant. W is the air side weight flow rate (target air flow rate to the refrigerant evaporator 17)
[kg/h], ΔT is the performance of the refrigerant evaporator 17 (the temperature difference [°C] between the surface temperature te of the refrigerant evaporator 17 and the temperature ti of the internal air), and φ is the performance coefficient of the refrigerant evaporator 17 (internal )
It is.

From the equation, it can be confirmed that in order to reduce ΔT and prevent qe from decreasing, Wφ should be increased. Therefore, when the refrigeration capacity Q of the refrigeration cycle 3 is constant, the target air flow rate W to the refrigerant evaporator 17 can be increased in order to reduce the performance ΔT of the refrigerant evaporator 17.

[0042] Therefore, the temperature and humidity of the air inside the refrigerator are set to 0°C.
and 90%, the amount of heat entering the refrigerator is 12
is known from the internal calorific value, and ΔT is also known because it can be calculated from the humidity of the air inside the refrigerator. Therefore, if the performance coefficient of the refrigerant evaporator 17 is determined by that refrigerant evaporator 17, the target air flow rate W to the refrigerant evaporator 17 can be determined.

Therefore, by controlling the current value or voltage value to the internal fan 5 in accordance with the target air flow rate W to the refrigerant evaporator 17 and increasing the rotational speed of the internal fan 5, the refrigerant evaporator 17 Increase the amount of air blown to. Therefore, the surface temperature of the refrigerant evaporator 17, that is, the performance of the refrigerant evaporator 17 is controlled, so that even if the refrigerating capacity of the refrigeration cycle 3 is reduced, the humidity of the air inside the refrigerator is maintained at 90%.

As described above, this refrigerator temperature/humidity control device 1 can control the temperature and humidity of the air inside the refrigerator at the same time. The humidity can be brought close to the set humidity. As a result, the inside of the refrigerator compartment 11 can be maintained at a low temperature and high humidity, so that the inside of the refrigerator compartment 11 has the optimal temperature and humidity for storing food, and the food is refrigerated with high freshness.

(Modification) In this embodiment, a solenoid valve that controls the opening time of the bypass pipe is used as the flow rate adjustment means, but a flow rate adjustment valve that controls the opening degree of the bypass pipe may also be used as the flow rate adjustment unit. good. The present invention may be utilized in a temperature/humidity control device for a freezer.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a temperature and humidity control device for a refrigerator used in an embodiment of the present invention.

FIG. 2 is a flowchart showing an example of temperature and humidity control of a control circuit.

[Figure 3] Relative humidity 60% and 9 at 760mmHg
It is a psychrometric diagram with 0%.

FIG. 4 is a graph showing the relationship between the refrigerating capacity of the refrigerating cycle and the temperature of the air inside the refrigerator.

[Figure 5] Relative humidity 60% and 9 at 760mmHg
It is a psychrometric diagram with 0%.

[Explanation of symbols]

1 Refrigerator temperature and humidity control device 2 Refrigerator body 3 Refrigeration cycle 5　Internal blower 6. Internal temperature sensor 7 Internal humidity sensor 8 Surface temperature sensor 9　Outside temperature sensor 10 Control circuit 13 Refrigerant compressor 14 Refrigerant condenser 17 Refrigerant evaporator 20 Bypass piping 21 Solenoid valve (flow rate adjustment means)

Claims (1)

[Claims] Claim 1: (a) a refrigerator body that stores food inside, (b) a refrigerant compressor that compresses and discharges refrigerant, and that exchanges heat between the refrigerant discharged from the refrigerant compressor and the air inside the refrigerator. a refrigerant evaporator, a refrigerant condenser that exchanges heat between the refrigerant flowing out from the refrigerant evaporator and the air outside the refrigerator, and a refrigerant compressor that bypasses the refrigerant evaporator and the refrigerant condenser to compress the refrigerant discharged from the refrigerant compressor. a refrigeration cycle having a bypass pipe for returning the refrigerant to the machine, and a flow rate adjustment means for adjusting the flow rate of the refrigerant flowing in the bypass pipe; (c) an internal blower for blowing internal air to the refrigerant evaporator; (d) (e) an outside temperature sensor that detects the temperature of the outside air; (f) an inside humidity sensor that detects the humidity of the inside air; (g) an inside temperature sensor that detects the temperature of the inside air; ) a surface temperature sensor that detects the surface temperature of the refrigerant evaporator; and (h)
Controlling the flow rate adjusting means according to the temperature of the inside air and the temperature of the outside air, and controlling the inside blower according to the humidity of the inside air and the surface temperature of the refrigerant evaporator. Refrigerator temperature and humidity control device equipped with a circuit.