JP3622611B2 - refrigerator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refrigerator of a type that performs defrosting by heating with a defrosting heater disposed below an evaporator.
[0002]
[Prior art]
In general, the structure of a household refrigerator can be broadly divided into a box / door part having a role of a heat insulating container / strength member and a refrigeration cycle part for cooling the inside of the room in terms of functions.
[0003]
Each box / door has an integrated structure with an outer box (mainly made of steel plate) sandwiching a heat insulating material (mainly made of urethane foam), and the inside of the box is a freezer or refrigerated room. A partition member (single heat insulating resin or a composite structure of resin and heat insulating material) for partitioning into a storage room or cold air passage, etc., and an interior member (mainly made of resin) for finely partitioning the storage room or the inside of the door ).
[0004]
In addition, the refrigeration cycle section circulates the refrigerant that is installed outside the cabinet, such as a compressor that boosts and circulates the refrigerant and a condenser that radiates heat outside the cabinet, an evaporator that is installed inside the cabinet and performs a cooling action, and the refrigerant. In order to achieve this, it is composed of a refrigerant pipe connecting the parts.
[0005]
In most of such refrigerators except small ones, the inside of the refrigerator is cooled by a cold air forced circulation system. It is an evaporator installed in a cold air duct, which is a separate compartment from the storage room, and collects and cools the cold air that circulates through each storage room (the refrigerant takes the heat from the cold air and evaporates here). Then, it is condensed while dissipating heat with a condenser outside the cabinet), and the cold air having a lower temperature is circulated to each storage chamber by a blower.
[0006]
In an evaporator (a heat exchanger with a structure in which a large number of fins penetrate through a refrigerant pipe), the cold air returning from the storage room is below the freezing point at the average temperature, and moisture from food in the warehouse Since the humidity of the cold air is high due to the invasion of humid air accompanying transpiration and opening / closing of the door, the moisture in the cold air condenses and freezes on the surface of the evaporator at a low temperature during heat exchange, and frost is formed.
[0007]
As a result of continuing the operation of the refrigerator, when the amount of frost formation in the evaporator increases to some extent, the heat exchange performance is significantly reduced due to a decrease in wind speed due to an increase in ventilation resistance, and the power consumption of the refrigerator is increased. Furthermore, when the air air path between the fins is almost closed with frost, the amount of heat exchange is greatly reduced, and normal operation of the refrigerator cannot be continued. In order to prevent this, in general, a defrost heater is arranged in the cold air duct slightly apart from the lower part of the evaporator, and the defrost is removed by heating the heater periodically or when the amount of frost formation increases. Is done.
[0008]
In such defrosting, the inside of the storage is not cooled during defrosting, the temperature of the storage room rises, and heating by a defrost heater or recooling after defrosting (evaporator and surroundings above freezing point) For example, it is desirable to improve the utilization efficiency of the heat of the heater in the defrosting to shorten the defrosting time because an extra power consumption is required for cooling the members. Therefore, conventionally, various improved techniques related to such a defrosting method have been disclosed.
[0009]
For example, Japanese Patent Laid-Open No. 8-110146 previously proposed by the inventors discloses that a heater cover above or below the defrost heater is a chevron plate, an inclined flat plate, or a curved surface plate that protrudes upward. It is intended to reduce the problem of the conventional defrost heater that the defrost water stays and is heated and evaporated to waste the heat of the defrost heater.
[0010]
Japanese Patent Application Laid-Open No. 10-292974 discloses that a defrost heater having an upper heater cover such as a chevron plate is arranged behind the cold air duct so that the warm air generated by the defrost heater is transferred only before and after the evaporator. Instead of discharging over a wide range, the convection of warm air in the cold air duct is more active than before, and the defrosting is made more efficient.
[0011]
[Problems to be solved by the invention]
Defrosting is intended to remove the frost from the evaporator by applying sensible heat and latent heat necessary for melting it to the defrosted water with a defrosting heater and guiding it to the drain outlet below the cold air duct. . When the defrost heater is activated, the heat from the heater body (typically a glass tube structure with nichrome wire inside) is heated to the frost of the evaporator by two mechanisms: radiation and convection. Reportedly.
[0012]
First, in radiation, the heat rays from the high-temperature heater body and the surrounding heater cover (generally made of aluminum plate) (heated by radiation from the heater body) reach the evaporator or frost directly or while reflecting off the surrounding wall. (This includes the amount that is transmitted from the heated evaporator by conduction) and is finally transmitted to frost. In this radiation process, excessive heating and evaporation of defrost water that has fallen on the cover and the wall surface are reflected on the heater cover and the surrounding wall where the heat rays are reflected. The rate will not be 100%, and the reflectivity will drop if wetted with water), with extra heating of the surrounding walls.
[0013]
In convection, the air around the heater body or between the heater body and the heater cover is warmed, discharged from the front and rear ends of the upper heater cover toward the evaporator, and convects upward and downward in the cold air duct that is elongated vertically. Heat is transferred to the evaporator and frost by warm air. In this convection process, the convection warm air not only heats the evaporator and frost but also the surrounding walls before and after the cold air duct.
[0014]
In conventional refrigerators, it is most common to use a defrost heater whose upper heater cover is a flat plate, but since defrost water tends to stay in the upper heater cover or the like, defrost water accompanying radiation There is a tendency for excessive heating and evaporation to increase. Also, since warm air is discharged from the two front and rear ends of the upper heater cover, the convection in the cold air duct is not strong, the heating of the evaporator and frost by the convection is weak, the defrosting time is extended, and the surrounding wall is excessive Heating also tends to increase. For these reasons, in the case of the most common conventional defrost heater in which the upper heater cover has a horizontal flat plate shape, there is a lot of wasted heating, which is disclosed in Japanese Patent Laid-Open No. 8-110146 previously proposed by the inventors. As shown, the amount of power effective for melting frost in the conventional method is estimated to be 1/3 or less of the amount of power input to the defrost heater.
[0015]
Moreover, in the conventional improvement technique disclosed in Japanese Patent Application Laid-Open No. 8-110146, although the drainage of the upper heater cover and the like is improved and excessive heating and evaporation of the defrost water is reduced, the upper heater cover is an inclined flat plate. However, there remains a defect that the generation of warm air in the defrost heater and the convection in the cold air duct do not become strong, and sufficient defrosting efficiency is not achieved.
[0016]
Further, in the conventional improvement technique disclosed in Japanese Patent Application Laid-Open No. 10-292974, excessive heating and evaporation of defrost water is reduced by the upper heater cover of the chevron plate, but only by deviating the defrost heater backward. There is a drawback that the convection in the cold air duct is not so strong and the heater cover only above does not increase the generation of warm air in the defrost heater, which is also not sufficient for efficient defrosting.
[0017]
An object of the present invention is to reduce the defrosting efficiency by reducing the excessive heating and evaporation of defrost water accompanying radiation from the defrost heater, and at the same time, strengthening the generation of warm air in the convection and the convection in the cold air duct. The improvement, that is, shortening of the defrosting time, is to reduce the power consumption accompanying defrosting and finally to reduce the power consumption of the refrigerator.
[0018]
[Means for Solving the Problems]
In order to achieve the above object, a refrigerator according to the present invention includes an evaporator, a defrost heater that is installed below the evaporator and includes a heater body and a heater cover provided around the heater body, and In a refrigerator including an evaporator and a cold air duct in which the defrost heater is disposed, the heater cover is configured as a substantially two-member structure that covers the front side and the rear side of the heater body, respectively. And the upper end of the front member of the heater cover is located above and behind the upper end of the rear member, and is bent from obliquely upward to downward. And the discharge port of the heater cover is located at a position biased to the rear side from the center of the cold air duct.
[0019]
In the refrigerator, the front member of the heater cover of the defrost heater has a shape in which a lower half portion protrudes while being inclined downward, or the defrost heater is located behind the center of the cold air duct in the front-rear direction. It may be arranged in a biased manner.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Prior to the description of the embodiment of the present invention, the structure around the evaporator of the refrigerator, the state of normal operation, and the state at the time of defrosting by the conventional defrosting heater will be described with reference to FIGS.
[0021]
FIG. 4 is a cross-sectional view of a conventional refrigerator having a defrost heater having a conventional structure as seen from the side of the lower half of the refrigerator box, and FIG. 5 shows heat transfer / defrosting of such a refrigerator. It is the fragmentary sectional view seen from the side of the evaporator periphery which showed the state of defrost water.
[0022]
In the cold air forced circulation refrigerator 1, each storage chamber 2 is insulated and partitioned by a box wall 3 and a door 4, and during normal operation, a cold air passage 5 (an evaporator 6 is vertically disposed inside) is partitioned separately from the storage chamber 2. It cools by circulating the cool air 9 sent from the defrost heater 7 in the lower part, and the blower 8 in the upper part. The evaporator 6 is cooled to about −30 ° C. by the refrigerant sent from other refrigeration cycle parts, and further cools by exchanging heat with the cold air 9 (the average temperature below the freezing point as a whole average temperature) that circulates and returns inside Then, the cooled cold air 9 is sent out again into the warehouse by the upper blower 8.
[0023]
The evaporator 6 is generally a heat exchanger having a structure in which a large number of fins 10 are integrated so as to penetrate the refrigerant pipe 11, and at a lower temperature than the cold air 9 below the freezing point returning from the storage chamber 2 during normal operation. In addition, since the returning cold air 9 has a high humidity due to moisture transpiration from food in the warehouse and the intrusion of humid air accompanying opening and closing of the door, the moisture in the cold air on the surface at the time of heat exchange Is condensed and frozen to form frost 14.
[0024]
Continuing the refrigerator operation will increase the amount of frost 14 adhering, and if it exceeds a certain level, the heat exchange performance will decrease due to the decrease in wind speed due to the increase in draft resistance, etc. The amount will increase. Further, when the air air path between the fins 10 is almost blocked by the frost 14, the refrigerator cannot be operated normally (the interior cannot be kept at the set temperature).
[0025]
In order to prevent this, in general, a defrost heater 7 is arranged in the cold air duct 5 slightly apart from the lower part of the evaporator 6, and the normal operation is interrupted regularly or when the amount of frost formation increases, etc. And defrosting is performed by melting and removing the frost 14 of the evaporator 6. If the frost 14 is removed from the evaporator 6 by defrosting, the heat exchange performance of the evaporator 6 is restored, and the refrigerator can also perform normal cooling operation.
[0026]
However, during defrosting, the interior of the storage chamber 2 is not cooled during defrosting, and it is necessary to recool after defrosting after heating the peripheral members other than frost 14 with defrosting. Therefore, it is desirable to improve the utilization efficiency of the heat of defrosting and shorten the defrosting time because of the power consumption.
[0027]
In the defrosting, the frost 14 of the evaporator 6 is given sensible heat and latent heat necessary for melting by the defrost heater 7 to be defrosted water 15, and a drain port below the cold air duct 5 (broken line in FIG. 5). To be removed). The conventional defrost heater 7 has a structure in which the heater body 12 that is a heat source is covered with a heater cover 13 (the upper cover is essential to prevent damage to the heater body 12 and noise generation due to dripping of the defrost water 15). It has become. When the defrosting heater 7 is operated, the heat from the heater main body 12 that has become high temperature (about 400 ° C.) is mainly radiated (the hot wire 16 is indicated by a zigzag arrow) and convection (the flow of the warm air 17 is indicated by a curved arrow). Is transmitted to the frost 14 of the evaporator 6 (however, heat is transferred from the warmed evaporator to the frost by conduction).
[0028]
In radiation, the heat rays 16 from the heater body 12 or the heated heater cover 13 reach the evaporator 6 and the frost 14 in the near range directly and further away from the surrounding wall while being reflected by the surrounding wall, and finally melt still. It is transmitted to the frost 14 of the non-defrosted portion (melting of the frost occurs in the form of gradually moving upward from the lower part of the evaporator close to the defrosting heater). In the defrost heater 7 having a conventional structure, since the upper heater cover 13 is a horizontal flat plate, most of the defrost water 15 falling from the evaporator 6 tends to stay in the upper heater cover 13 (water droplets / water film is large). Therefore, the defrosted water 15 is heated to an excessive temperature above the freezing point or part of the defrosted water 15 is evaporated, resulting in heat loss. In addition, even if aluminum tape or the like is applied to the surrounding wall and the reflectance is increased, the surrounding wall is excessively heated by radiation because it is reflected many times or the surface is wet with water, and heat loss Occurs.
[0029]
In convection, air is warmed around the heater body 12 or between the heater body 12 and the heater cover 13 to generate warm air 17, and the warm air 17 having a low density rises upward in the cold air duct 5 to evaporate the evaporator 6. Then, the temperature is lowered by touching the frost 14 or the like, the density is increased, and a flow is formed in which it descends from the middle and returns to the defrost heater 7. In the defrost heater 7 having the conventional structure, the warm air 17 is discharged upward from the two front and rear ends of the horizontal flat plate-shaped upper heater cover 13, and the defrost heater 7 is moved in the front-rear direction of the cold air duct 5. Therefore, the rising warm air 17 flows slightly spread around the center of the cold air duct 5 (since it is discharged from two locations). In contrast to the rising warm air 17, the warm air 17 descending the cool air duct 5 flows closer to the front and rear surrounding walls. Convection is possible.
[0030]
In this way, if the upflow and the downflow overlap in a narrow duct, they are easy to mix with each other, so that only weak convection that does not reach the upper side can be formed, and heat is not easily transmitted to the upper evaporator 6 or frost 14. If heat transfer to the evaporator 6 and the frost 14 due to convection is weak and takes a long time, the heat loss due to extra warming of the surrounding wall flowing along it also increases. Further, in the defrost heater 7 having the conventional structure, the heater cover 13 has many openings, and the heat rays 16 reflected from the inner surface of the heater cover 13 are difficult to gather in the heater body 12. There is also a drawback that the generation of warm air 17 does not become strong.
[0031]
Therefore, in a refrigerator having a defrost heater having a conventional structure, there is an inefficiency in heat transfer from the defrost heater to frost by radiation and convection during defrosting, the defrosting efficiency is low, and power consumption associated with defrosting The amount is thought to be increasing.
[0032]
Next, the state at the time of defrosting by the defrosting heater to which the conventional improved technique is applied is demonstrated.
[0033]
FIG. 6 is a side view of the evaporator around the side showing the state of heat transfer / defrost water during defrosting in a refrigerator to which the conventional improved technique of Japanese Patent Laid-Open No. 8-110146 described in the prior art is applied. FIG.
[0034]
In this refrigerator, the upper part of the heater cover 13 of the defrosting heater 7 is an inclined plate with a front lowering. With such a heater cover 13, the defrosted water 15 that has fallen does not stay in the upper heater cover 13, but immediately flows down, so heat loss due to radiation due to excessive heating and evaporation of the defrosted water 15. Will be small. On the other hand, in convection, warm air 17 discharged from the upper heater cover 13 is discharged more from the rear end surface, which is the upper side of the inclined plate, but is also discharged from the front end surface with a small amount. The convection of the warm air 17 formed in 5 has two upper and lower systems as in the conventional structure, and the convection cannot be so strong. As in the case of the conventional structure, the shape of the heater cover 13 does not increase the warm air 17 generated in the defrost heater 7.
[0035]
Therefore, in a refrigerator with a defrost heater using the conventional improved technology, heat transfer due to radiation during defrosting is improved, but inefficiency remains in heat transfer due to convection. Is not sufficient, and it is considered that the reduction in power consumption accompanying defrosting is not sufficient.
[0036]
FIG. 7 is a side of an evaporator surrounding the state of heat transfer / defrost water at the time of defrosting in a refrigerator to which another conventional improvement technique of Japanese Patent Laid-Open No. 10-292974 described in the prior art is applied. It is the fragmentary sectional view seen from the direction.
[0037]
In this refrigerator, the heater cover 13 of the defrost heater 7 is in the shape of a chevron plate only at the upper portion, and the defrost heater 7 is arranged so as to be biased rearward from the front-rear center of the cold air duct 5. In the case of such a heater cover 13, the defrost water 15 is unlikely to stay in the upper heater cover 13 as in the above-described conventional improved technology. The heat loss is small. On the other hand, in the convection, although the position of the defrost heater 7 is biased to the rear side from the center of the cold air duct, the warm air 17 discharged from the upper heater cover 13 is discharged in the same amount from the front and rear ends of the chevron plate. Therefore, the convection of the warm air 17 formed in the cold air duct 5 is limited to the extended upward flow along the front and rear peripheral walls (mainly the front side), and the convection cannot be so strong. . As in the case of the conventional structure, the shape of the heater cover 13 does not increase the warm air 17 generated in the defrost heater 7.
[0038]
Therefore, even in a refrigerator having a defrosting heater according to another conventional improvement technique, heat transfer due to radiation during defrosting is improved, but inefficiency remains in heat transfer due to convection. It is considered that the improvement in the power consumption is not sufficient, and the reduction in power consumption accompanying defrosting is not sufficient.
[0039]
Furthermore, the state at the time of defrosting by the defrosting heater of the typical structure of this invention is demonstrated.
[0040]
FIG. 8 is a partial cross-sectional view seen from the side of the periphery of the evaporator showing the state of heat transfer / defrost water during defrosting in a refrigerator to which the defrosting heater of the present invention is applied.
[0041]
In the defrosting heater 7 having the configuration of the present invention, the heater cover 13 has a substantially two-member structure that covers the front side and the rear side of the heater body 12, and the lower and upper openings of the heater body 12 are warm air 17. It is a suction port and a discharge port. The heater cover 13 can be formed as a single member including both axial end portions of the heater body 12 if the front and rear members are connected in a ladder shape at the suction port and the discharge port. is there. At the upper discharge port of the heater cover 13, the upper end of the front member extends to a position above and behind the upper end of the rear member, and is bent from the diagonally upward direction to the downward direction only near the tip like a ridge. In addition, the position of the discharge port is biased to the rear side from the center of the cold air duct 5 in the front-rear direction.
[0042]
With such a defrosting heater according to the present invention, the defrosting water 15 does not stay on the outer surface of the heater cover 13 because of the radiation at the time of defrosting, and the front side and the rear side of the heater cover 13 do not stay. Although the side overlaps vertically at the discharge port, the defrosted water 15 does not enter the inside of the cover because the upper end of the front side portion that comes up has a bowl shape. As a result, extra heating and evaporation of the defrost water 17 inside and outside the heater cover 13 can be less than that of the conventional improved technology.
[0043]
In convection, first, since the heater cover 13 covers the front and back, there are few openings, and the heat rays 16 reflected from the inner surface of the heater cover 13 are also likely to gather in the heater body 12, so that warm air 17 is generated in the defrost heater 7. There is an advantage that increases. Further, since the discharge port is formed as a gap between the upper ends of the front and rear members, there is only one discharge port in the front-rear direction of the cold air duct 5. Furthermore, the discharge port of the heater cover 13 is biased to the rear side from the center of the cold air duct 5 in the front-rear direction. Accordingly, since the warm air 17 generated a lot in the defrost heater 7 is concentrated and discharged from the rear outlet at one location, it rises along the rear peripheral wall in the cool air duct 5 and the front periphery. A flow of warm air 17 descending along the wall is formed. This convection has a large amount of warm air 17 generated and has only one system of rising and lowering in the cold air duct 5 that is vertically elongated, so that there is little mixing on the way and it is strong that reaches upward. If the convection is strong and heat is easily transmitted to the upper evaporator 6 and the frost 14, the frost will not take time to melt and the heating of the surrounding walls flowing along it will be reduced.
[0044]
Therefore, in the refrigerator to which the defrosting heater of the present invention is applied, heat transfer by radiation and convection during defrosting becomes efficient, so that the defrosting efficiency is sufficiently improved and the power consumption accompanying defrosting is reduced. It will be possible.
[0045]
The inventors conducted a model experiment simulating the defrosting state of the refrigerator in order to quantitatively check the defrosting performance of the above-described conventional structure, the conventional improved technology, and the defrosting heater in the configuration of the present invention. .
[0046]
As a model experiment method for defrosting, only the cold air duct part is constructed using actual refrigerator parts and styrofoam plates, and heat is exchanged with low-temperature and high-humidity air while flowing below the freezing point through the evaporator. In a state where the fluid and air were stopped, the defrost heater was energized to defrost, and the amount of defrost water and the time change of each part temperature were measured. The specifications of the defrost heaters tested are the conventional structure ("conventional type") that has already explained the defrost state with reference to FIGS. 5 to 8, the conventional improved technique (Japanese Patent Laid-Open No. 8-110146, "the improved technique"). A ") and other conventional improvement techniques (Japanese Patent Laid-Open No. 10-292974," Improvement technique B "), and the configuration of the present invention (" present invention ").
[0047]
FIG. 9 is a diagram comparing the defrost characteristics of the conventional structure in the defrost model experiment and the defrost heater of the conventional improved technology. Compared with the “conventional type” of the conventional structure, the “improved type A” of the conventional improved technology defrosts in almost the same time even though the final amount of defrosted water discharged below the cold air duct is about 10%. This is a slight improvement (however, the rise of the air temperature at the top of the evaporator is slightly slower for “Improved A”). This is a result supporting the qualitative explanation already given that the efficiency of radiant heat transfer for defrosting is improved in “modified type A” rather than “conventional type”, but the efficiency of convective heat transfer does not change much. .
[0048]
FIG. 10 shows similar defrosting characteristics for the conventional structure and other conventional defrosting heaters. In this case, the final value of the amount of defrost water is about 10% longer in the “improved type B” of another conventional improved technique than the “conventional type” of the conventional structure, but the defrost time is also about 10% longer. Therefore, there is not much improvement (the rise of the air temperature at the top of the evaporator is also slightly slower with “improved type B”). In the explanation that has already been given, the efficiency of radiant heat transfer for defrosting is improved in "Improved type B" rather than "conventional type", but the efficiency of convective heat transfer is not changed so much. However, there is no improvement such as qualitative explanation.
[0049]
FIG. 11 shows similar defrosting characteristics for the conventional structure and the defrosting heater of the present invention. Unlike the above-mentioned two conventional improved technologies, the “present invention” of the configuration of the present invention has a time shorter by 10% or more than the “conventional type” although the final defrost water amount is 50% more. Defrosting has been completed (the rise of the air temperature at the top of the evaporator is considerably faster in the “present invention”). This coincides with the explanation already made that the improvement is great because both the radiant heat transfer and the convective heat transfer of the defrost are efficiently performed in the present invention rather than the “conventional type”.
[0050]
From the results of the above defrost model experiment, the defrost heater having the configuration of the present invention is used to improve the defrost efficiency from the conventional structure, which is larger than in the case of the conventional improved technology, that is, to shorten the defrost time and defrost. It turns out that the reduction of the power consumption accompanying it is obtained.
[0051]
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
[0052]
FIG. 1 is a partial cross-sectional view around the defrosting heater for the refrigerator according to the first embodiment of the present invention. The structure of the defrosting heater according to the first embodiment of the present invention is substantially the same as that described above as the defrosting heater having the typical configuration of the present invention in FIG. Has a substantially two-member structure in which the heater cover 13 covers the front side and the rear side of the heater body 12, respectively, and the lower and upper openings of the heater body 12 serve as a suction port and a discharge port for the warm air 17, respectively. . Also heater cover
In the upper 13 outlet, the upper end of the front member extends to a position above and behind the upper end of the rear member, and is bent obliquely upward to downward near the tip like a ridge, Further, the position of the discharge port is also deviated from the center in the front-rear direction of the cold air duct 5 to the rear side.
[0053]
If it is such a defrost heater of this invention, as already demonstrated in FIG. 8, in the radiant heat transfer at the time of defrost, the outer surface of the heater cover 13 is almost only a slope, and defrost water 15 stays. In addition, the front side and the rear side of the heater cover 13 overlap each other vertically at the discharge port, but the upper end of the front side portion that rises has a bowl shape so that the defrost water 15 does not enter the cover. As a result, extra heating and evaporation of the defrosted water inside and outside the heater cover 13 can be less than that of the conventional improved technology, and if the heater cover 13 does not get so wet and the temperature is high, radiation of the hot wire 16 from the surface is also possible. It will also increase.
[0054]
In the convection, first, the heater cover 13 covers the front and back, so there are few openings, and the heat rays 16 reflected from the inner surface of the heater cover 13 are also likely to gather in the heater body 12. Occurrence increases. Further, since the discharge port is formed as a gap between the upper ends of the front and rear members, the discharge port of the heater cover 13 is located behind the center of the cold air duct 5 in the front-rear direction. It is biased to the side. Accordingly, since the warm air 17 generated a lot in the defrost heater 7 is concentrated and discharged from the rear outlet at one location, it rises along the rear peripheral wall in the cool air duct 5 and the front periphery. A flow of warm air 17 descending along the wall is formed.
[0055]
This convection has a large amount of warm air 17 generated and has only one system of rising and lowering in the cold air duct 5 that is vertically elongated, so that there is little mixing on the way and it is strong that reaches upward. If the convection is strong and heat is easily transmitted to the upper evaporator 6 and the frost 14, the frost will not take time to melt and the heating of the surrounding walls flowing along it will be reduced.
[0056]
From the above, in the refrigerator according to the first embodiment of the present invention, radiation during defrosting by the defrost heater and heat transfer by convection become efficient, so that the defrosting efficiency is sufficiently improved and defrosting is performed. The accompanying power consumption can be reduced.
[0057]
FIG. 2 is a partial cross-sectional view around the defrosting heater for the refrigerator of the second embodiment according to the present invention. The structure of the defrosting heater according to the second embodiment of the present invention is characterized in that the front side member of the heater cover 13 of the defrosting heater 7 has a shape in which the lower half portion protrudes while inclining forward. . Even if there is such a difference in structure, it is considered that the defrosting state compared to the first embodiment of the present invention may be caused by the fact that the amount of warm air 17 generated is slightly reduced or remains the same. As can be seen, the effect of improving the defrosting characteristics of the defrosting heater 7 from the conventional structure is almost the same, and the improvement of the defrosting efficiency and the reduction of the power consumption associated with the defrosting are obtained as well.
[0058]
On the other hand, the accompanying effects peculiar to the defrosting heater in the second embodiment of the present invention include the following. During normal operation of the refrigerator, most of the cool air 9 flows in from the front side of the cool air duct 5 while colliding with the defrost heater 7, and is immediately bent upward and directed to the evaporator 6. In the defrosting heater according to the first embodiment of the present invention shown in FIG. 1, the lower half of the front member of the heater cover 13 is nearly vertical, so that this flow may be disturbed compared to this book. In the defrosting heater according to the second embodiment of the invention, the lower half of the front member of the heater cover 13 is inclined forwardly downward, so that a large amount of cool air 9 is smoothly directed toward the upper evaporator 6. It can flow. Thereby, the heat exchange performance of the evaporator 6 can be improved by increasing the air volume of the cool air 9 and reducing the turbulence during normal operation of the refrigerator, and the power consumption of the refrigerator can be reduced.
[0059]
FIG. 3: is a fragmentary sectional view around the defrost heater about the refrigerator of 3rd Embodiment which becomes this invention. The structure of the defrosting heater according to the third embodiment of the present invention is characterized in that the defrosting heater 7 is arranged so as to be biased rearward from the center in the front-rear direction of the cold air duct 5. Even if there is such a difference in structure, the defrosting state compared to the first embodiment of the present invention is substantially the same as the convection state formed by the biasing of the suction port as well as the discharge port of the warm air 17. As can be seen from the above description, the improvement effect from the conventional structure related to the defrosting characteristics of the defrosting heater 7 is almost the same, and the improvement of the defrosting efficiency and the power consumption accompanying defrosting are the same. A reduction is obtained as well.
[0060]
On the other hand, the defrosting heater according to the third embodiment of the present invention has the same incidental effect as that of the second embodiment of the present invention. In the third embodiment of the present invention, the defrost heater 7 is shifted to the rear side of the cold air duct 5 with respect to the cold air 9 that flows into the defrost heater 7 from the front side of the cold air duct 5 during normal operation of the refrigerator. Since the front side is wide, most of the cool air 9 can flow smoothly toward the upper evaporator 6. As a result, as in the second embodiment of the present invention, the heat exchange performance of the evaporator 6 can be improved by increasing the air volume or reducing the turbulence of the cold air 9 during normal operation of the refrigerator so that the power consumption of the refrigerator can be reduced. Become.
[0061]
【The invention's effect】
According to the present invention, excessive heating and evaporation of defrost water accompanying radiation from the defrost heater can be reduced, and at the same time, generation of warm air in convection and convection in the cold air duct can be strengthened. The power consumption accompanying defrosting can be reduced and the power consumption of the refrigerator can be reduced.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view around a defrost heater in a refrigerator according to a first embodiment of the present invention.
FIG. 2 is a partial cross-sectional view around a defrost heater in a refrigerator according to a second embodiment of the present invention.
FIG. 3 is a partial cross-sectional view around a defrost heater in a refrigerator according to a third embodiment of the present invention.
FIG. 4 is a cross-sectional view of the lower half of the box of a conventional refrigerator as viewed from the side.
FIG. 5 is a partial sectional view showing a state of heat transfer / defrost water at the time of defrosting as seen from the side of the periphery of the evaporator in a conventional refrigerator.
FIG. 6 is a partial cross-sectional view seen from the side of an evaporator and its surroundings showing the state of heat transfer / defrost water during defrosting in a refrigerator to which a conventional improved technique is applied.
FIG. 7 is a partial cross-sectional view seen from the side of an evaporator and its surroundings showing the state of heat transfer / defrost water during defrosting in a refrigerator to which another conventional improved technique is applied.
FIG. 8 is a partial cross-sectional view showing the state of heat transfer / defrost water at the time of defrosting as seen from the side around the evaporator in the refrigerator of the present invention.
FIG. 9 is a characteristic diagram showing a comparison between defrosting characteristics in a defrosting heater of a conventional structure and a conventional defrosting heater in a defrosting model experiment.
FIG. 10 is a characteristic diagram comparing the defrosting characteristics of a conventional defrosting heater in a defrosting heater according to another conventional technology and a conventional structure in a defrosting model experiment.
FIG. 11 is a characteristic diagram comparing the defrost characteristics of the conventional structure in the defrost model experiment and the defrost heater of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 5 ... Cold air duct, 6 ... Evaporator, 7 ... Defrost heater, 9 ... Cold air, 12 ... Heater main body, 13 ... Heater cover, 14 ... Frost, 15 ... Defrost water, 16 ... Hot wire, 17 ... Warm air.

Claims (1)

Cold air in which an evaporator, a defrost heater installed below the evaporator and including a heater main body and a heater cover provided around the heater main body, and the evaporator and the defrost heater are disposed inside In a refrigerator including a duct, the heater cover has a substantially two-member structure that covers a front side and a rear side of the heater body, respectively, and a suction port and a discharge port are formed below and above the heater body, and The upper end of the front member of the heater cover is located above and behind the upper end of the rear member at the discharge port, and is bent obliquely from upward to downward, and the discharge port of the heater cover is cooled by the cold air. A refrigerator characterized by being placed at a position biased to the rear side of the center of the duct.

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