JP3444718B2 - Rice storage refrigerator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rice storage refrigerator for storing rice at a low temperature. 2. Description of the Related Art As a conventional apparatus of this type, for example, as shown in Japanese Patent Publication No. 7-63272, an inside of a refrigerator having a predetermined width and depth is disclosed. On the ceiling, there was a rice and rice storage provided with a cooler for maintaining the temperature in the storage within the range of 5 ° C. to 15 ° C. during the period when the outside air temperature was 16 ° C. or more. Further, as another conventional apparatus, there is a conventional apparatus in which a unitized commercial cooler including a refrigeration cycle is installed in an existing refrigerator. According to the document "Frozen" (Vol. 62, No. 711, July 1987, pp. 739 to 742), "Agricultural Product Refrigerator for Local Use" (by Saburo Yasui), the temperature in the refrigerator is 13 ° C. If the humidity is set to 70 to 80%, the weight loss, generation of mold,
It describes that the activity of cereal elephants is prevented and rice can be stored for a long time. [0004] In the above-mentioned conventional apparatus, the internal temperature can be easily reduced by one.
Although it can be maintained at about 2 ° C., little consideration has been given to relative humidity. FIG. 8 shows a time change of humidity and temperature in a conventional rice and rice storage in which a compressor forming a refrigeration cycle is turned on and off by a thermosensitive element such as a thermostat.
(A) shows the change over time in the relative humidity H _IN in the refrigerator, (b) shows the outside air temperature T _OUT , the temperature in the refrigerator T _IN , the refrigerant temperature T _E1 on the inlet side of the evaporator, and the refrigerant temperature T in the middle of the evaporator. ₉ shows the time change of _E2 and the refrigerant temperature _{TE3 at} the evaporator outlet side, respectively.
In this case, the relationship between the heat leakage quantity and chiller refrigerating capacity of the refrigerator, the operation time and operation interval of the compressor is short either, therefore, evaporator refrigerant temperature T _E1 of the incoming side is -6 ° C. of about frost formation amount is reduced only by lowering the relative humidity H _iN in the refrigerator
Is always 80% or more. FIG. 9 shows the time variation of the humidity and temperature in the refrigerator when a commercially available cooler that controls the compressor on and off in the same manner is used. From the relationship between the amount of heat leak and the refrigerating capacity of the cooler, the operation time and the operation interval of the compressor are both long, so that the refrigerant temperature T _E1 on the inlet side of the evaporator is approximately −8 ° C. to −10 ° C. And the relative humidity H _IN is about 68-9.
It varies between 8%. [0006] Thus, in the conventional apparatus, since the time required to reach 70 to 80%, which is optimal for long-term storage of rice, is short, it was difficult to suppress the occurrence of mold. By the way, constant temperature that keeps not only the temperature inside the refrigerator but also the humidity inside the refrigerator at the set value,
A constant-humidity bath would certainly increase the price of the equipment, even if it is effective for long-term storage of rice. The present invention has been made in view of the above circumstances, and uses a refrigerator including a refrigeration cycle in which refrigeration capacity, evaporation temperature, and the like are appropriately set, so that a rice storage refrigerator suitable for long-term storage of rice. The purpose is to provide. [0008] If the relationship between the amount of heat leak in the refrigerator for storing rice and the refrigerating capacity of the cooler is changed, the frost formation state of the evaporator changes, and this frost formation state is changed. The humidity in the refrigerator changes according to the change. Now, the ratio between the amount of heat leak in the refrigerator and the refrigeration capacity is set as the operation rate, and the temperature in the refrigerator is set to 12 ° C. during the maximum capacity operation and the minimum capacity operation of the cooler having the variable capacity refrigeration cycle. FIG. 7 shows the relationship between the operation rate and the relative humidity in the refrigerator. As is clear from this figure, the higher the operating rate, in other words, the lower the relative humidity in the refrigerator, the lower the cooling capacity that is used as compared with the amount of heat leak. In general, assuming that the cooler is operated at or near the maximum capacity, the operating rate is set to approximately 40% in order to control the temperature in the refrigerator to about 12 ° C. and to make the relative humidity in the refrigerator 70 to 80%. We need to make sure that: In FIG. 8 illustrating the conventional apparatus, the refrigerant temperature T _E1 on the inlet side of the evaporator is about −6 ° C., and there is only a temperature difference of about 18 K from the set temperature of 12 ° C.
The relative humidity in the refrigerator is over 80% for most of the period. On the other hand, in the conventional apparatus shown in FIG. 9, the refrigerant temperature T _E1 on the inlet side of the evaporator is about −10 ° C., and the set temperature is 12 ° C.
It is considered that there is a period in which the relative humidity in the refrigerator is in a state of 70 to 80% from this relation. When a thermostat is used as a temperature sensing element, there is a difference between a set temperature and a return temperature. If the difference is too small, excessive operation and stop of the compressor are repeated. Conversely, if the difference between the set temperature and the return temperature is too large, the amount of change in the amount of frost is large, and the period during which the desired humidity state is maintained becomes short. Therefore, the present invention is provided with a temperature-sensitive element capable of setting the temperature in the refrigerator to a desired value, and the operating rate when the temperature in the refrigerator is controlled using this temperature-sensitive element is about 40%. % Of refrigeration capacity, this cooler has a fan inside the refrigerator that sucks in and blows out cold air,
An evaporator provided in the outlet path, wherein the temperature of the refrigerant flowing into the evaporator is about 22 to 2 compared to the set temperature in the refrigerator.
A refrigeration cycle that generates a temperature difference of 6K is provided, and the temperature-sensitive element is a thermostat having a difference between a set temperature and a return temperature of about 2K, and on / off control of a compressor constituting the refrigeration cycle using the thermostat. As a result, the relative humidity in the refrigerator can be reduced to approximately 70 to 80%, thereby obtaining a rice storage refrigerator suitable for long-term storage of rice. Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a perspective view showing an entire configuration of an embodiment of the present invention, and a rice storage refrigerator 1.
Comprises a storage 2 having a predetermined width and depth and a caster mounted on the bottom surface, and a cooler 10 mounted on the ceiling thereof. The storage 2 is provided with a door 3 in the front part, the door 3 is opened to load and unload the paper bags 5 filled with rice, and the cooling device 10 is operated with the door 3 closed during storage. ing. FIGS. 2 (a) and 2 (b) are a plan view and a side view showing a detailed configuration of the cooler 10, showing the arrangement of the main elements in a state where a cover to be protected is removed. ing. In the figure, when the substrate 7 is installed on the ceiling of the storage 2, an opening 6 is formed in the storage 2, and it is possible to suck cool air in the storage from the opening 6. A cooling housing 8 is formed on a substrate 7 corresponding to the opening 6, and an evaporator 15 and a fan 19 inside the refrigerator are accommodated therein. A blow-off duct 9 is provided below the evaporator 15, and cool air in the refrigerator is sucked in by a fan 19 in the refrigerator, and cool cool air is blown out from the side of the blow-out duct 9 through the evaporator 15. . Further, on the substrate 7, in addition to the compressor 11, the condenser 12, the dryer 13, the external fan 18 and the like forming a well-known refrigeration cycle, an electric component box 30 containing a knob for temperature control and the like is also mounted. Have been. FIG. 3 is a system diagram of a refrigeration cycle formed by the compressor 11, the condenser 12, the evaporator 15, and the like. Here, the refrigerant discharged from the compressor 11 is supplied to the condenser 1
After being changed to a liquid refrigerant by 2, it is supplied to an evaporator 15 via a dryer 13 and a capillary tube 14, where it is converted to a gas refrigerant and sucked into a compressor 11. The outside fan 18 shown in FIG. 3 is for promoting the heat exchange of the condenser 12, and similarly, the inside fan 19 shown in FIG. 3 is for promoting the heat exchange of the evaporator 15. is there. The dryer 13 absorbs water dissolved in the refrigerant, and the capillary tube 14 lowers the pressure of the refrigerant flowing from the condenser 12 to the evaporator 15 due to frictional resistance in the tube, and supplies a low-pressure liquid flow to the evaporator 15. It is for. In addition, when the amount of frost on the evaporator 15 is too large, the defrosting is performed and the defrosting of the drain plate is performed so that the discharge side of the compressor 11 and the inlet side of the liquid refrigerant of the evaporator 15 are connected. In between, the two-way valve 16 for defrosting and the drain pan hot gas pipe 17 are connected in series, and by opening the two-way valve 16 for defrosting during defrosting, the drain pan (not shown) and the evaporator 15 are removed. It is configured to perform frost. FIG. 4 is a control circuit diagram for the refrigeration cycle system shown in FIG. In the figure, components denoted by the same reference numerals as those in FIG. 2 or 3 indicate the same components, respectively. Here, an AC power supply connected by the AC plug 20
Compressor drive motor CM, main relay RY1, two-way valve SV for defrost, return reed switch 25, auxiliary relay RY2,
The internal fan motor EFM and the external fan motor CFM are connected. One of the power supply paths to the compressor drive motor CM includes a normally open contact ry1 of the main relay RY1.
1 and an overload relay 21 are connected in series, and a start capacitor SC, a phase advance capacitor RC, and a starter 22 are connected in series on the other power supply path to the compressor drive motor CM. Note that the compressor drive motor CM is a single-phase induction motor having a main winding and an auxiliary winding, and the starter 22 has a built-in posistor 23, and when starting up, both the start-up capacitor SC and the phase-advancing capacitor RC are used. This is used to advance the current phase of the auxiliary winding and determine the rotation direction. After that, the influence of the starting capacitor SC is reduced by the posistor 23 having a high resistance value, and the current phase of the auxiliary winding is advanced mainly by the phase advance capacitor RC to form a predetermined rotating magnetic field, thereby starting the compressor 11. Drive. A main relay RY connected to an AC power supply
1, a thermostat 24 is connected in series,
When the thermostat 24 is turned on due to a rise in the internal temperature, the main relay RY1 is excited, the compressor drive motor CM is energized by closing the contact ry11, and is closed by closing the other normally open contact ry12. Power is supplied to the fan motor CFM. On the other hand, each time a predetermined time elapses, the defrosting timer TM switches the contact t for switching only for the time necessary for defrosting.
m, and normally energizes the internal fan motor EFM and the external fan motor CFM. The defrosting two-way valve SV is energized by switching and connecting the contact tm during defrosting. EFM and outside fan motor C
The power supply to the FM is shut off. That is, the defrosting two-way valve SV is opened while the in-compartment fan motor EFM and the out-of-compartment fan motor CFM are stopped, and defrosting is performed by passing the gas refrigerant through the drain dish hot gas pipe 17 and the evaporator 15 (see FIG. 3). ). A switching contact ry21 of an auxiliary relay RY2 is connected in series to the defrosting two-way valve SV.
A series connection circuit of the return reed switch 25 and the auxiliary relay RY2 is connected in parallel to a series connection circuit of the y21 and the defrosting two-way valve SV. The return reed switch 25 is a so-called defrosting detection relay that is turned on when the amount of frost on the evaporator 15 becomes equal to or less than a predetermined value. When defrosting is detected during energization of the valve SV, the return reed switch 25 is turned on to excite the auxiliary relay RY2.
As a result, the contact ry21 is opened and the two-way valve S for defrosting is opened.
Power supply to V is cut off. On the other hand, the auxiliary relay RY2 forms a self-holding circuit via the contact ry21 and closes another contact ry22 at this time. Therefore, regardless of the state of the contact tm of the defrost timer TM, the fan inside the refrigerator is not used. Electric power is supplied to the motor EFM and the external fan motor CFM. Thus, every time the defrosting timer TM elapses a predetermined time, the defrosting operation is performed by energizing the defrosting two-way valve SV for the set time. When the operation is completed, the cooling operation is started without waiting for the defrosting timer TM to time out. Subsequently, when the inside of the refrigerator is cooled by the cooling operation and the thermostat 24 returns to the open state, the main relay RY1 is de-energized, the contact ry11 is opened, the compressor drive motor CM is stopped, and the contact ry12 is opened and the external fan motor CFM is also stopped. In this state, only the in-compartment fan motor EFM continues to be driven. Thereafter, when the temperature inside the storage rises due to the heat leak of the storage 2, the thermostat 24 is closed again and the same operation as described above is repeated. Generally, the refrigerating capacity of the cooler 10 is determined by the capacity of the compressor 11, the sizes of the condenser 12 and the evaporator 15, the characteristics of the capillary tube 14, and the like.
In the present embodiment, when the set temperature of the storage 2 is set to 12 ° C., the amount of heat absorbed by the evaporator 15 is about 2.5 times or less the amount of heat leaked from the storage 2, that is, the operation is performed. The refrigeration capacity is set so that the rate does not fall below about 40%. When the thermostat 24 is set at 12 ° C., a thermostat having a difference between the set temperature and the return temperature of about 2K is used. [0026] FIG. 5 (a) the time change of the internal relative humidity H _IN of case where the chiller 10 by a refrigeration cycle having a refrigeration capacity described above, FIG. 5 (b) the outside air temperature T _OUT,
The time changes of the in- _compartment temperature T _IN , the refrigerant temperature T _E1 on the inlet side of the evaporator, the refrigerant temperature T _{E2 in} the middle portion of the evaporator, and the refrigerant temperature T _E3 on the outlet side of the evaporator are shown. In this case, when the set temperature of the thermostat 24 is set to 12 ° C. and the compressor 11 is operated with the thermostat 24 turned on, the refrigerant temperature T _E1 on the inlet side of the evaporator becomes about −12 to −14 ° C. Then, the relative humidity in the refrigerator decreases, and the internal temperature of the refrigerator slightly increases in response to the stoppage of the compressor 11, and the relative humidity in the refrigerator also increases. However, when the relative humidity in the refrigerator reaches 85%, the operation in which the temperature in the refrigerator reaches about 14 ° C. and the compressor 11 is operated again is repeated. The relative humidity in the refrigerator while the compressor 11 is operating is about 70%. Thus, according to the present embodiment, a cooling machine having a refrigerating capacity with an operation rate of more than about 40% when the internal temperature is controlled using a thermostat that can be set to 12 ° C. is provided. It is possible to maintain the relative humidity in the refrigerator at 70-80% over most of the operation period, thereby obtaining a rice storage refrigerator suitable for long-term storage of rice. The refrigerant temperature T _E1 on the inlet side of the evaporator and the set temperature are approximately 24
By having a temperature difference of ２６26 K, the relative humidity in the refrigerator can be maintained at about 70-80%. Furthermore, in the present embodiment, a thermostat having a difference between the set temperature and the return temperature of about 2K is used, so that it is possible to prevent the compressor from being repeatedly operated and stopped repeatedly. [0028] Figure 6 using a thermostat difference 3K between the set temperature and the return temperature, when carrying out the temperature control by opening and closing, the internal relative humidity H _IN, outside air temperature T _OUT, the internal temperature T _IN , The refrigerant temperature T _E1 on the inlet side of the evaporator,
Shows the respective time changes in the refrigerant temperature T _E3 coolant temperature T _E2 and the evaporator outlet side of the intermediate portion of the evaporator. In this case, the difference is the internal relative humidity of about 22 with the refrigerant temperature T _E1 of the input-side setting for thermostat 24 temperature and the evaporator is 66 to 90
%, It can be seen that the time required to deviate from the ideal relative humidity in the refrigerator becomes longer. When comparing the time change of the relative humidity in the refrigerator shown in FIG. 5 and FIG.
It is clear that the one having a difference between the set temperature and the return temperature of about 2K is optimal. In the above embodiment, a thermostat is used as a temperature-sensitive element. However, another temperature-sensitive element such as a thermistor is used to make the difference between the set temperature at which the compressor 11 operates and the return temperature 2K. Even in this case, the same effect as described above can be obtained. In the above embodiment, the case where the difference between the set temperature and the refrigerant temperature T _E1 on the inlet side of the evaporator is about 24K to 26K is described. Can be maintained for about 70-80%, which is quite effective from the viewpoint of long-term storage of rice. As is apparent from the above description, according to the present invention, a temperature-sensitive element capable of setting the temperature in a refrigerator to a desired value is provided. Equipped with a cooler having a refrigerating capacity with an operation rate of more than about 40% when the temperature is controlled, the relative humidity in the refrigerator can be maintained at an appropriate value. A refrigerator is obtained. In this case, the refrigeration cycle in which the temperature of the refrigerant flowing into the evaporator causes a temperature difference of about 22 to 26 K as compared with the set temperature in the refrigerator is provided. The relative humidity can be maintained at about 70-80%. Further, since the compressor is turned on and off using a thermostat that can be set to about 12 ° C. and has a difference between the set temperature and the return temperature of about 2 K as a temperature sensing element, the compression is controlled. Excessive running and stopping of the machine can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a configuration of an embodiment of the present invention. FIGS. 2A and 2B are a plan view and a side view showing a detailed configuration of a cooler constituting the embodiment shown in FIG. FIG. 3 is a refrigeration cycle system diagram of the embodiment shown in FIG. 1; FIG. 4 is an electric circuit diagram showing a configuration of the control device of the embodiment shown in FIG. FIG. 5 is a diagram showing a relationship between time and relative humidity in the refrigerator, outside air temperature, temperature in the refrigerator, refrigerant temperature on the inlet side of the evaporator, and the like, for explaining the operation of the embodiment shown in FIG. . FIG. 6 is a diagram showing a relationship between time and relative humidity in the refrigerator, outside air temperature, temperature in the refrigerator, refrigerant temperature on the inlet side of the evaporator, and the like, for explaining the operation of the embodiment shown in FIG. . FIG. 7 is a diagram showing the relationship between the relative humidity in the refrigerator and the operation rate, with the refrigeration capacity as a parameter, for explaining the principle of the present invention. FIG. 8 is a diagram showing the relationship between time and the relative humidity in the refrigerator, the outside air temperature, the temperature in the refrigerator, the temperature of the refrigerant on the inlet side of the evaporator, and the like of the conventional rice storage refrigerator. FIG. 9 is a diagram showing a relationship between time and relative humidity in the refrigerator, outside air temperature, temperature in the refrigerator, refrigerant temperature on the inlet side of the evaporator, and the like of the conventional rice storage refrigerator. [Description of Signs] 1 Refrigerator for storing rice 2 Storage 10 Cooler 11 Compressor 12 Condenser 15 Evaporator 16 Two-way valve for defrosting 18 Outside fan 19 Inside fan 22 Activator 24 Thermostat 25 Reed switch for return CM Compressor drive motor SC Start capacitor RC Phase advance capacitor TM Defrost timer RY1 Main relay RY2 Auxiliary relay SV Defrost two-way valve EFM Internal fan motor CFM External fan motor

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kimio Fushimi 336 Tatehara, Fuji City, Shizuoka Prefecture Inside the Fuji Plant, Toshiba Corporation (56) References JP-A-7-246022 (JP, A) JP-A-2-115567 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F25D 11/00 101

Claims (1)

(1) A rice storage refrigerator for storing rice at a low temperature, the rice storage refrigerator including a temperature-sensitive element capable of setting a temperature in a refrigerator to a desired value. A cooler having a refrigerating capacity with an operation rate of more than about 40% when the temperature in the refrigerator is controlled using the refrigerator, wherein the cooler sucks and blows cold air in the refrigerator.
And the evaporator provided in the cold air intake and
The temperature of the refrigerant flowing into the evaporator is the set temperature in the refrigerator.
Temperature of about 22-26K
The temperature-sensitive element has a difference between a set temperature and a return temperature of about 2K.
It ’s a thermostat that uses this thermostat
ON / OFF control of the compressor constituting the refrigeration cycle
A refrigerator for storing rice.