JP2003232590A - Refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the danger due to combustion in defrosting in the environment where the combustible refrigerant leaks in a refrigerator using combustible refrigerant. <P>SOLUTION: A defrosting means 26 composed of a metal pipe 48, a heater wire 37 and an insulating material 49 is disposed below an evaporator 10, a water catch tray 50 with a heating means is provided on the lower part of the defrosting means 26 to heighten the defrosting efficiency, and the surface temperature during defrosting operation of the defrosting means 26 is held below an ignition point of the flammable refrigerant to reduce the possibility of ignition when the flammable refrigerant leaks. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator. 2. Description of the Related Art In recent years, a refrigerator having improved defrosting efficiency is disclosed in Japanese Patent Application Laid-Open No. 8-54172. Hereinafter, the above-mentioned conventional refrigerator will be described with reference to the drawings. FIG. 5 is a longitudinal sectional view of a main part of a conventional refrigerator. In FIG. 5, 1 is a refrigerator main body, 2 is a freezing room inside the refrigerator main body 1, 3 is a refrigerator room inside the refrigerator main body 1, 4 is a freezing room door, 5 is a refrigerator room door, and 6 is a refrigerator room door. A partition wall separating the freezer compartment 2 and the refrigerator compartment 3, a refrigerator inlet 7 for sucking air in the freezer compartment 2, a refrigerator inlet 8 for sucking air in the refrigerator compartment 3, and a discharge outlet 9 for discharging cool air. Reference numeral 10 denotes an evaporator, and 11 denotes a fan for circulating cool air. Reference numeral 12 denotes an evaporator partition wall for separating the evaporator 10 and the freezing compartment 2, 13 denotes a tub, 14 denotes a drain port, 15 denotes a defrosting tube heater in which a coiled nichrome wire is covered with a glass tube, Reference numeral 16 denotes a roof for preventing the evaporation noise generated when the defrost water directly drops on and contacts the defrost tube heater 15.
Reference numeral 7 denotes a metal bottom plate provided between the tub 13 and the defrosting tube heater 15 and insulated and held. Next, the operation will be described. When cooling the freezer compartment 2 or the refrigerator compartment 3, the refrigerant flows through the evaporator 10 to cool the evaporator 10. Fan 11 in the same way
, The heated air of the freezing room 2 or the refrigeration room 3 is sent from the freezing room suction port 7 or the refrigeration room suction port 8 to the cooling chamber 20, the heat is exchanged by the evaporator 10, and the cooling air is cooled from the discharge port 9. The wind is sent into the freezer compartment 2, and cool air is sent from the freezer compartment 2 to the refrigerator compartment through a communication port (not shown). Here, the air that exchanges heat with the evaporator 10 is:
Since the air is humidified by the inflow of high-temperature outside air due to the opening and closing of the freezer compartment door 4 and the refrigerating compartment door 5 and the evaporation of moisture in the preserved food in the freezer compartment 2 and the refrigerating compartment 3, the temperature is lower than the air. Moisture in the air becomes frost and forms frost on the evaporator 10,
As the amount of frost increases, the heat transfer between the surface of the evaporator 10 and the air that exchanges heat is hindered, and the air flow decreases due to airflow resistance. As a result, the heat transfer rate decreases, resulting in insufficient cooling. Therefore, before the cooling becomes insufficient, the nichrome wire of the defrosting tube heater 15 is energized. When energization of the nichrome wire is started, heat rays are radiated from the nichrome wire to the evaporator 10 and peripheral components. At this time, a part of the heat ray radiated to the bottom plate 17 is reflected by the heater wire from the shape of the bottom plate 17, and the others are reflected toward the evaporator 10 and other peripheral parts. Thus, the evaporator 10, the tub 13, the drain 1
The frost that has arrived near 4 is melted in water. A part of the defrosted water thus melted falls directly into the tub 13, and the other falls into the tub 13 by the roof 16, avoiding the defrosting tube heater 15, and is discharged from the drainage port 14 to the outside of the refrigerator. You. However, in the above-mentioned conventional construction, the temperature of the glass surface is, of course, very high, not to mention the surface of the nichrome wire of the defrosting tube heater 15, and the bottom plate. Reference numeral 17 denotes a portion of the heat ray radiated from the tube heater 15 in the vicinity of the tube heater 15.
, The temperature of the tube heater 15 rises abnormally. The heating value of the tube heater 15 is the same as that of the tube heater 1.
5 is the sum of the amount of heat used to raise the temperature and the amount of heat radiated to the outside. Therefore, an increase in the temperature of the tube heater 15 means a decrease in the amount of heat radiated to the outside. Since the defrosting of the evaporator 10 and its peripheral parts is performed, the amount of heat used for defrosting the evaporator 10 and its peripheral parts is reduced, the defrosting time is extended, and as a result, the heat generation time of the tube heater 15 is reduced. Prolong and increase power. Accordingly, the power is increased, and a flammable refrigerant is used as the refrigerant, and when the flammable refrigerant leaks from a pipe installed in a portion communicating with the evaporator 10 or the inside of the refrigerator, a defrosting pipe heater is used. There is a problem that the risk of ignition by reaching the ignition temperature by the energization of No. 15 becomes extremely high. SUMMARY OF THE INVENTION In view of the above problems, the present invention aims at saving energy of a refrigerator by reducing electric power used for defrosting, and in an environment where used and combustible refrigerant leaks into an installation atmosphere of a defrosting means. An object of the present invention is to provide a refrigerator that can safely use a flammable refrigerant because the possibility of ignition of the flammable refrigerant can be reduced even when defrosting is performed. According to a first aspect of the present invention, there is provided a refrigeration cycle in which a compressor, a condenser, a decompression mechanism, and an evaporator are connected, and the evaporator is defrosted. Defrosting means for, comprising a water tray with heating means installed below the evaporator, using a flammable refrigerant for the refrigeration cycle,
The defrosting means includes a metal pipe, a heater wire made of a metal resistor installed inside the metal pipe, and an insulating material for insulating the heater wire and the metal pipe, Since the heat transfer from the defrosting means to the evaporator is good and the defrosting ability is improved, the calorific value of the defrosting means can be reduced when maintaining the same defrosting ability as before,
The surface temperature of the defrosting means can be lowered, and the defrosting means does not reach the ignition temperature of the combustible refrigerant. Further, since the water receiving pan with heating means is heated, it is possible to smoothly discharge the dropped defrost water around the evaporator and the evaporator to the outside. With the increase, it is possible to prevent the ventilation resistance of the evaporator from increasing and insufficient cooling. From the above, it is possible to save energy and at the same time maintain the same defrosting ability as in the past, while maintaining the same defrosting ability even in the case where the flammable refrigerant leaks into the installation atmosphere of the defrosting means. In addition to reducing the risk of ignition of the refrigerant, it is possible to prevent food deterioration due to insufficient cooling after defrosting. Embodiments of the present invention will be described below with reference to the drawings. In addition, about the same structure as a conventional one, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted. (Embodiment 1) Embodiment 1 according to the present invention will be described with reference to the drawings. FIG. 1 is a refrigeration system diagram of a refrigerator according to the first embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of a main part of the refrigerator according to the first embodiment of the present invention. As shown in FIGS. 1 and 2, reference numeral 18 denotes a compressor,
19 is a condenser, 20 is a switching valve for switching the flow path of the refrigerant,
21 is a low evaporating temperature decompression mechanism having a large decompression amount for the low evaporating temperature, 22 is a high evaporating temperature decompression mechanism having a small decompression amount for the high evaporating temperature, and 23 is a cooling for a refrigerator compartment having a high evaporating temperature for refrigerating. , 24 is a refrigerator for a freezer compartment having a low evaporation temperature for freezing, and 25 is a check valve for preventing a backflow of refrigerant from the compressor 18 or the refrigerator cooler 23 to the refrigerator cooler 24. . 26 is a defrosting means for defrosting the freezer compartment cooler, 27 is a freezer compartment partition wall separating the freezer compartment and the freezer compartment cooler, and 28 is a freezer compartment air. Freezer fan for ventilating and circulating air through the cooler 24,
Reference numeral 9 denotes a freezer compartment discharge port for discharging air cooled by heat exchange in the freezer compartment cooler 24 to the freezer compartment 2, and reference numeral 30 denotes a refrigerator compartment cooler partition wall separating the refrigerator compartment 3 and the refrigerator compartment cooler 23. , 3
Reference numeral 1 denotes a refrigerator compartment fan for ventilating and circulating the air in the refrigerator compartment 3 to the refrigerator compartment cooler 23, and 32 discharges air cooled by the heat exchange in the refrigerator compartment cooler 23 to the refrigerator compartment 3. The refrigerating compartment discharge port 33 is an evaporating dish for storing defrosted water when the defrosting means 26 defrosts the freezer compartment cooler 24. With respect to the refrigerator configured as described above,
The operation will be described below. When the refrigerator compartment 3 is cooled, when the refrigerator compartment 3 reaches a certain set temperature or higher, the compressor 18 is operated by a temperature detecting means (not shown) and circulation of a combustible refrigerant (not shown) in the refrigerating cycle starts. The combustible refrigerant is supplied to the condenser 19
The refrigerant is condensed by heat exchange with the outside air, passes through the high evaporating temperature decompression mechanism 22 by the switching valve 20, flows to the refrigerator cooler 23, and is sucked into the compressor 18 to form a refrigerating room cooling refrigerating cycle. . At this time, by operating the refrigerating compartment fan 31 simultaneously with the operation of the compressor 18, the air in the refrigerating compartment 3 is sucked in from the refrigerating compartment suction port 8 and passed through the refrigerating compartment cooler 23 to exchange heat. The cooled air is discharged from the refrigerator outlet 32 to the refrigerator 3 to cool the refrigerator 3. Also, at any time during which the compressor 18 is stopped, the refrigerating room fan 31 is operated, and the refrigerating room 3 is operated.
The air having a temperature exceeding 0 ° C. is passed through the refrigerator cooler 23. At this time, the frost formed on the refrigerator cooler 23 is defrosted while increasing the absolute humidity of the air passing through the refrigerator cooler 23. The air having the increased absolute humidity is discharged from the refrigerator outlet 32. When the freezing compartment 2 is cooled, when the freezing compartment 2 reaches a certain set temperature or higher, the compressor 18 is activated to start circulation of the flammable refrigerant in the refrigeration cycle, and the flammable refrigerant is discharged from the condenser. The refrigerant is condensed by heat exchange with the outside air at 19, flows through the low evaporating temperature reducing mechanism 21 through the switching valve 20 to the freezing room cooler 24, and is sucked into the compressor 18. Become. When the freezing room fan 28 is operated at the same time as the operation of the compressor 18, the air in the freezing room 2 is sucked from the freezing room suction port 7 and is passed through the freezing room cooler 24 to exchange heat and cool. The cooled air is discharged from the freezer compartment outlet 29 into the freezer compartment 2 to cool the freezer compartment 2. At this time, since the air flowing through the freezer compartment cooler 24 is air only in the freezer compartment 2, the amount of frost on the freezer compartment cooler 24 is reduced. Immediately after the compressor 18 stops after an elapse of an arbitrary time, or when the compressor 18 is in operation, the compressor 18 is stopped, and at the same time, the defrosting means 26 is operated, and the freezing room fan 28 is stopped. The operation of the defrosting means 26 causes the defrosting means to generate heat, and the heat generated by the defrosting means 26 is transferred to the freezer compartment cooler 24 to perform defrosting. At this time, at the start of defrosting,
Normally, the refrigerant flows backward from the refrigerator cooler 23 to the refrigerator cooler 24 whose evaporation temperature is lower than that of the refrigerator cooler 23, but in the present embodiment, the check valve 25 prevents the refrigerant from flowing back. Defrosting is performed. Further, the freezer compartment cooler 2 of the defrosting means 26
The refrigerant in the pipe of the freezer compartment cooler 24 is also heated by the heating of 4, and is gasified and discharged from the freezer compartment cooler 24. Even the discharged refrigerant may flow backward by the check valve 25. There is no. When the temperature of the freezer compartment cooler 24 and its surroundings reaches a certain temperature exceeding 0 ° C. at which the frost melts, the defrosting is completed. At this time, the defrosted water that has melted and becomes water is appropriately dropped and stored in the evaporating dish 33, and is evaporated using the waste heat generated by the operation of the compressor 18 accompanying the cooling after the completion of the defrosting, and is evaporated to the outside air. Is discharged. Accordingly, when the freezer compartment cooler 24 is being defrosted, the amount of frost to be removed by the defrosting means 26 is reduced by reducing the amount of frost formed in the freezer compartment cooler 24, and the check valve 25, it is not necessary to heat the wasteful refrigerant flowing backward to the freezer compartment cooler 24.
Energy consumption by reducing the power consumption of
Since the calorific value of the defrosting means 26 can be reduced to a calorific value that is lower than the ignition temperature of the flammable refrigerant, the environment in which the flammable refrigerant leaks into the installation atmosphere of the defrosting means 26 while maintaining the defrosting ability at or above the conventional level. Even when defrosting is performed below, the possibility of ignition of the combustible refrigerant can be reduced. (Embodiment 2) Embodiment 2 according to the present invention will be described with reference to the drawings. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted. FIG. 3 is a cross-sectional view of a main part of a refrigerator according to a second embodiment of the present invention, and FIG. 4 is a cross-sectional view of a main part of a defrosting means. As shown in FIGS. 3 and 4, reference numeral 48 denotes a metal pipe which is a component of the defrosting means 26, reference numeral 49 denotes an electrically insulating material, and reference numeral 50 denotes a water tray provided with heating means. Regarding the refrigerator configured as described above,
The operation will be described below. At the time of defrosting, the defrosting means 26 and the heating means attached to the water pan 50 with heating means generate heat and the temperature rises, and the defrosting means 26 defrosts the frost formed on itself and evaporates. The evaporator 10 is defrosted by heating the evaporator 10. Here, a part of the defrosting water that has not been discharged during the previous defrosting and remains in the water receiving tray with heating means 50 becomes ice during cooling and remains. Since the defrosting means 26 and the water tray 50 with heating means are installed so that heat transfer with frost and ice is improved, most of the heat generated by the defrosting means 26 and water tray 50 with heating means is reduced. Since it is absorbed by frost and ice, defrosting is performed at a surface temperature slightly higher than the melting point of frost and ice. When the defrosting is completed, the temperatures of the defrosting means 26 and the water receiving tray with heating means 50 also gradually rise, but the operation is stopped by the end of the defrosting, so that the temperature rise is eliminated. Further, since the refrigerant in the evaporator 10 heated simultaneously with the frost is a flammable refrigerant having good heat conductivity, the defrosting efficiency is further improved. From this, the defrosting means 26 can reduce the heat generation and the temperature can be further lowered by improving the defrosting ability in addition to lowering the temperature. While ensuring the defrosting ability of
The heater wire 37 can be set at a temperature lower than the ignition temperature of the flammable refrigerant, and the possibility of ignition can be reduced even if defrosting is performed when the flammable refrigerant leaks into the atmosphere of the defrosting means 26. In addition, since the evaporator 10 and the defrost water in the vicinity of the evaporator 10 that have fallen into the water tray 50 with heating means can be smoothly discharged to the outside, frost formation due to poor discharge of the defrost water can be achieved. With the increase, it is possible to prevent the ventilation resistance of the evaporator 10 from increasing and insufficient cooling, so that deterioration of food can be prevented. As described above, the first aspect of the present invention provides a refrigeration cycle in which a compressor, a condenser, a pressure reducing mechanism, and an evaporator are connected, and a method for defrosting the evaporator. A defrosting means, and a water tray with heating means installed below the evaporator; a flammable refrigerant is used for the refrigeration cycle; and the defrosting means is installed inside a metal pipe and the metal pipe. Since the heater wire made of a metal resistor and the insulating material for insulating the heater wire and the metal pipe are formed, the defrosting means improves the defrosting ability in addition to the temperature decrease. As a result, the heating value can be reduced and the temperature can be further reduced, so that the heater wire can be set at a temperature lower than the ignition temperature of the flammable refrigerant while saving energy and at the same time maintaining the same or higher defrosting capacity as before. Is the atmosphere of the defrosting means The possibility of ignition can be reduced even if defrosting is performed in the event of leakage. In addition, since the evaporator and the defrosted water around the evaporator that have fallen into the water pan with the heating means can be smoothly discharged to the outside, evaporation due to increased frost formation due to defective discharge of the defrosted water. As a result, it is possible to prevent the ventilation resistance of the vessel from increasing and insufficient cooling, thereby preventing the food from deteriorating.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a refrigeration system diagram of a refrigerator according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of a main part of the refrigerator according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view of a main part of a refrigerator according to a second embodiment. FIG. 4 is a cross-sectional view of a defrosting means of the refrigerator according to a second embodiment of the present invention. 1 Refrigerator body 2 Freezer compartment 3 Refrigerator compartment 10 Evaporator 14 Drain outlet 16 Roof 18 Compressor 19 Condenser 20 Switching valve 21 Low evaporating temperature decompression mechanism 22 High evaporating temperature decompression mechanism 23 Refrigerating room cooler 24 Freezing room Cooler 25 Check valve 26 Defrosting means 37 Heater wire 48 Metal pipe 49 Insulating material 50 Water pan with heating means

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Koichi Nishimura             2-3-1, Nojihigashi, Kusatsu-shi, Shiga Prefecture             Matsushita Refrigeration Co., Ltd. F term (reference) 3L046 AA05 BA04 CA06

Claims (1)

Claims: 1. A refrigeration cycle in which a compressor, a condenser, a decompression mechanism, and an evaporator are connected, a defrosting means for defrosting the evaporator, Provided with a water tray with heating means installed, using a flammable refrigerant for the refrigeration cycle, the defrosting means, a metal pipe, a heater wire consisting of a metal resistor installed inside the metal pipe, A refrigerator comprising an insulating material for insulating the heater wire and the metal pipe.