KR100706726B1 - Refrigerator - Google Patents

Abstract

Not only the heater wire surface of the defrost heater but also the glass tube surface temperature is very high temperature, and the protective plate is in the vicinity of the defrost heater, thereby damaging the rubber stopper sealing both ends of the glass tube.

In a refrigerator in which a heater wire wound in a coil shape is incorporated in a glass tube, and a defrost heater in which both ends are sealed with a rubber stopper is provided in the lower part of the cooler, a heat dissipation member (heat radiating fin) attached so that the circumference is in contact with or close to the outer circumference of the glass tube. ) Is installed between the rubber stoppers, and an upper cover having a heat dissipation effect is provided to contact the heat dissipation member.

Defrost heater, glass tube, heater wire, heat generating fin, rubber stopper

Description

Refrigerator {REFRIGERATOR}

1 is a longitudinal sectional view of a refrigerator provided with the present invention;

Figure 2 is an enlarged view of the main part of Figure 1;

3 is an explanatory view of a defrost heater cross section of FIG. 2;

4 is a perspective view of the heat radiation fin in FIG.

FIG. 5 is an enlarged perspective view of a main part of a defrost heater illustrating an embodiment different from FIG. 3. FIG.

6 is a view for explaining a winding direction of a heat radiation fin and a heater wire of the defrost heater provided with the present invention;

FIG. 7 is a view of the defrost heater in FIG. 5 viewed in the direction of an arrow, showing a relationship with a trough; FIG.

8 is an AA cross-sectional view of FIG. 2.

FIG. 9 is an explanatory diagram of a defrost heater cross section illustrating an embodiment different from FIG. 5; FIG.

10 is a perspective view of the heat radiation fin of FIG.

11 is a perspective view of a heat radiation fin different from that of FIG.

12 is a Q-arrow diagram of FIG.

Fig. 13 is a diagram explaining a coil pitch and the like of a defrost heater.

14 is an explanatory view of a refrigeration cycle having the present invention.

15 is a longitudinal sectional view of a conventional refrigerator.

FIG. 16 is a cross-sectional explanatory view of the defrost heater part in FIG. 15; FIG.

17 is an enlarged explanatory diagram of a main part of FIG. 15;

<Explanation of symbols for the main parts of the drawings>

1, 51: refrigerator body

2, 52: freezer

3, 53: cold storage room

4, 54: freezer door

5, 55: refrigerator door

6, 56: middle partition wall

7, 8, 57, 58: passage

9, 59: cooler chamber

10, 29, 60: cooler

11, 31, 61: defrost heater

11a, 31a, 61a: glass tube

11b, 31b, 61b: heater wire

11c, 61c, b: coil end part

12, 30, 62: cold air circulation fan

13, 63: compartment partition

14, 64: cold air outlet

15, 23, 65: top cover

15a, 20c: attachment leg

15b: fastening attachment member

16, 22: heat dissipation member (heat dissipation fin)

16a: center hole

17, 32, 70: rubber stopper

17a: attachment groove

18: positioning member

19, 35, 68: lead wire

20, 67: gutter

20a: drain

20b: metal plate for gutter heating

21, 34, 69: connection member

23a: ceiling

23b: vertical member

24, 36: heat dissipation fin

25: hole

26: compressor

27: condenser

28: capillary tube

a: coil part

33: partition plate

38: stopper

71: lead wire through hole

[Document 1] Japanese Patent Application Laid-open No. Hei 8-54172

[Document 2] Japanese Patent Laid-Open No. 2000-283635

The present invention relates to a refrigerator having a defrost heater for defrosting frost attached to a cooler in a refrigeration cycle.

As a prior art regarding the refrigerator provided with a defrost heater, there exist some described in patent document 1. As shown in FIG. In this example, the defrosting tube heater covered with the glass tube which made the nichrome wire into the coil shape below the cooler is provided. A roof is provided between the cooler and the defrosting tube heater to prevent defrost water dropped from the cooler from directly contacting the defrosting tube heater. In addition, between the defrosting tube heater and the lower trough there is provided a bottom side electrically insulated and retained to protect the trough, and when the defrost heater is broken, the heater wire is draped down to the trough to open the trough. It prevents damage and prevents a short circuit through defrosting water.

In addition, Patent Document 2 discloses a defrost heater having a heater wire provided in a sheath tube filled with an insulating material and sealed with an insulating material in order to make the defrost heater temperature below the isobutane ignition temperature of the refrigerant. It is described.

[Patent Document 1] Japanese Patent Application Laid-open No. Hei 8-54172

[Patent Document 2] Japanese Patent Laid-Open No. 2000-283635

Hereinafter, the subject in the prior art is demonstrated. 15 is a view showing a conventional refrigerator. The refrigerator main body 51 has a freezing compartment 52 and a refrigerating compartment 53 therein, and an intermediate partition wall 56 partitioning therebetween is provided. The front opening part of the freezer compartment 52 is provided with the freezing compartment door 54 which closes this opening part, and the front opening part of the refrigerating compartment 53 is provided with the refrigerating compartment door 55 which closes this opening part.

The intermediate partition wall 56 is provided with a passage 57 for returning the cold air heat exchanged with the food in the freezing compartment 52 to a cooler described later and a passage 58 for returning the cold air heat exchanged with the food in the refrigerating chamber 53 to the cooler. It is. A cooler chamber 59 communicating with the freezing chamber 52 and the refrigerating chamber 53 via the passage 57 and the passage 58 is provided behind the freezing chamber 52, and inside the cooler chamber 59, a cooler ( 60), a defrost heater 61, and a cold air circulation fan 62. A partition partition 63 partitioning between the chambers is provided between the cooler chamber 59 and the freezing chamber, and a cold air outlet 64 is formed in the partition partition 63. The cold air cooled by heat exchange with the cooler 60 by these structures is taken out from the cold air blower outlet 64 to the freezing chamber 52 by the cold air circulation fan 62.

In Fig. 16, an aluminum roof 65 is provided between the defrost heater 61 and the cooler 60, and when the frost attached to the cooler 60 is melted by the heat of the defrost heater, the defrost water is directly defrosted. Prevent contact with the heater.

Usually, the surface temperature of the glass tube 61a of a defrost heater becomes the temperature of 500 degreeC vicinity at the time of defrosting. For this reason, when water droplets drop directly into the glass tube during defrost, a water vapor explosion state is generated and a loud sound is generated. The sound generated when the state is close to the water vapor explosion state is a sound enough to be heard to the outside of the refrigerator, giving anxiety to the user. Preventing this is the role of the roof 65.

A protective plate 66 made of aluminum is provided under the defrost heater 61, and the protective plate 66 is a resin trough 67 for draining out the defrost water when the glass tube 61a is broken by an impact or the like. ) To protect. Fig. 16 shows a state in which the glass tube 61a is broken by an impact or the like, and the protective plate 66 prevents the heater wire 61b from falling down and coming into contact with the trough 67. Since the protection plate 66 made of aluminum is insulated and held, even if the heater wire 61b falls down on the protection plate 66, the electricity leaks to the metal part of the refrigerator main body 51. There is no

When cooling the freezing chamber 52 or the refrigerating chamber 53, a coolant flows through the cooler 60 to cool the cooler 60. By the action of the cold air circulation fan 62 which is operated at the same time, the cold air cooled by heat exchange with the cooler 60 is taken out from the cold air outlet 64 to the freezing chamber 52. The cold air taken out into the freezer compartment 52 cools the frozen food in the freezer compartment 52 and returns to the cooler 60 and the defrost heater 61 through the passage 57. On the other hand, the refrigerating chamber 53 side has a structure in which the cold air cooled by the cooler 60 is taken out into the refrigerating chamber 53 by using a cooler circulation passage 62 although not shown in the drawing. Here too, the food is cooled by heat exchange with the food. The cold air after cooling is returned to the cooler 60 and the defrost heater 61 through the passage 58.

Since the freezer door 54 and the refrigerating compartment door 55 are opened and closed, outside air containing moisture flows into the refrigerator, so that the air in the refrigerator becomes air containing moisture. In addition, when the moisture contained in the food in the freezer compartment 52 and the refrigerating compartment 53 evaporates, the air in the refrigerator is similarly air containing moisture. Thus, since the air containing moisture heat-exchanges with the cooler 60, the moisture becomes frost in the cooler 60, and it deposits and accumulates. As the deposition amount increases, heat transfer with the air that exchanges heat with the surface of the cooler 60 is inhibited, and at the same time, the ventilation resistance is reduced, and the air volume decreases. As a result, the heat passing rate decreases and cooling shortage occurs.

Thus, energization of the defrost heater 61 is started before this lack of cooling occurs. When the electric current is started to the heater wire 61b, a hot wire is radiated from the heater wire 61b via the glass tube 61a to the cooler 60 and peripheral components. At this time, a part of the hot wire radiated to the protective plate 66 is reflected by the heater wire 61b through the glass tube 61a from the shape of the protective plate 66. In addition, some of the defrost water melted by the heat from the defrost heater falls directly into the trough 67, and the rest falls to the roof 65. In addition, since this roof 65 is low temperature compared with the glass tube 61a, steam explosion does not reach here.

In general, the heater wire 61b surface temperature and the glass tube 61a surface temperature of the defrost heater 61 become very high temperature. This is because the protection plate 66 is in the vicinity of the defrost heater 61, the heat wire once radiated through the glass tube is reflected by the protection plate 66, and abnormally heating not only the glass tube 61a but also the heater wire 61b. It also comes from doing.

When the glass tube 61a and the heater wire 61b are overheated in this way, there is a possibility that the rubber stoppers for sealing both ends of the defrost heater 61 may be damaged by heat. In order to solve the problem of the damage of the rubber stopper, if the coil end portion (the straight portion braided by folding the heater wire 61b which is not a coil type to a predetermined length) is made long at the end of the heater wire 61b, There has been a problem in that defrosting of the frost attached to the cooler 60 in the upper portion of the coil end is delayed and the defrosting time is long.

In addition, since the tube diameter of the defrost heater 61 of the shape shown in FIG. 17 is 1/4 to 1/5 small with respect to the depth dimension D1 of the cooler 60, a heating wire is the whole of the cooler 60. As shown in FIG. There was a problem that the defrosting time was delayed because it did not evenly reach the depth D1.

Reference numeral 68 in Fig. 16 denotes a lead wire for supplying power to the heater wire 61b, and 69 denotes a connecting member of the lead wire 68 and the heater wire 61b. In addition, 70 has shown the rubber stopper which seals the both ends of the glass tube 61a, 71 has shown the hole for letting the lead wire 68 provided in the said rubber stopper 70 pass.

Moreover, as described in patent document 2, when the heater wire was set as the structure which covers an insulation material, there existed the following problems. When the heater wire is energized, the heater wire generates heat, so that not only the sheath tube but also the insulation material covering the heater wire itself is heated. In the above-mentioned patent document 2, since the both ends of a sheath tube are sealed with a cap, when a periphery of a heater wire is covered with an insulating material, heat is transmitted to a cap via an insulating material. At this time, even if a high heat resistance property such as silicone rubber is used for the cap, the heat resistance temperature is about 145 ° C, and if the temperature is higher than the heat resistance temperature, the cap is damaged. In this case, it is necessary to separately install a heat insulating member between the insulating material and the cap.

In the case where a flammable refrigerant is used, if the heat generation temperature of the heater wire is set lower when the refrigerant leaks, the output as the defrost heater is lowered and the defrost performance as the defrost heater is lowered. On the other hand, if the insulating material itself is excellent in heat insulating properties, the temperature of the heater wire cannot be transmitted to the outside, and in this case, the performance as a defrost heater is reduced.

In addition, since the defrost heater itself is arrange | positioned near the lower part of a cooler, at the time of normal operation of a refrigerator, the ambient temperature becomes negative 30 degrees C or less. The heater wire is hundreds of degrees in the defrosting operation, but it is not considered the expansion and contraction of the insulating material against these temperature changes.

An object of the present invention is to provide a refrigerator in which a rubber stopper for sealing the glass tube end of the defrost heater is prevented from being damaged by heat.

Another object of the present invention is to provide a refrigerator in which a refrigerant using a hydrocarbon-based refrigerant as a refrigerant prevents flammability by a defrost heater while suppressing a decrease in defrosting performance even if a refrigerant leaks in the refrigerator. have.

The above object is a refrigerator having a heater wire disposed in a lower portion of a cooler and wound in a coil shape disposed in a glass tube, and a defrost heater having a rubber stopper for sealing both ends of the glass tube, wherein the inner circumference is provided between the rubber stoppers. It is achieved by providing the heat radiating member attached to the said glass tube outer periphery or adjoining, and making the clearance gap of the heater wire and the glass tube wound by the said coil shape into 0.5 mm or less.

Another object of the present invention is to provide a defrost heater having a heater wire disposed in a lower portion of a cooler through which a hydrocarbon-based refrigerant flows and wound in a coil shape disposed in a glass tube, and a rubber stopper for sealing both ends of the glass tube. A refrigerator, comprising: a heat dissipation member provided between the rubber stoppers, the inner circumference of which is attached to or in contact with the outer circumference of the glass tube, wherein the heater wire has an ability to rise in temperature near the ignition temperature of the refrigerant, and defrost. This is achieved by selecting the heat dissipation member so that the temperature of the heater wire at the time of operation becomes lower than the ignition temperature of the refrigerant.

An embodiment of the present invention will be described below with reference to FIGS.

1 is a longitudinal cross-sectional view of a refrigerator provided with the present invention, FIG. 2 is an enlarged view of a main part of FIG. 1, FIG. 3 is a cross-sectional view of a defrost heater in FIG. 2, FIG. FIG. 5 is an enlarged perspective view of an essential part of a defrost heater illustrating an embodiment different from FIG. 3, FIG. 6 is a view illustrating a winding direction of a heat radiation fin and a heater wire of the defrost heater according to the present invention, and FIG. Fig. 8 is a view showing the relationship between the trough through the defrost heater in the direction of arrow P in FIG. 8, FIG. 8 is a cross-sectional view corresponding to the AA section of FIG. 2, and FIG. 10 is a perspective view of the heat radiation fin of FIG. 9, FIG. 11 is a perspective view of the heat radiation fin different from FIG. 9, and FIG. 12 is a Q arrow view of FIG. FIG. 13 is an explanatory diagram of a coil pitch and the like of the defrost heater, and FIG. 14 is an explanatory diagram of a refrigeration cycle including the present invention.

(First embodiment)

First, in Figs. 1 to 4, the refrigerator main body 1 has a freezing chamber 2, a refrigerating chamber 3, and the like therein. The front face of the freezer compartment 2 is provided with a freezer compartment door 4 that closes the opening, and the front face of the freezer compartment 3 is provided with a refrigerator compartment door 5 that closes the opening. An intermediate partition wall 6 is provided between the freezer compartment 2 and the refrigerating compartment 3 to divide the chambers, and the intermediate partition wall 6 is returned to a cooler which will be described later with cold air that has exchanged heat with food in the freezer compartment 2. The channel | path 7 which makes a path | route 7 and the channel | path 8 which returns the cold air heat-exchanged with the food in the refrigerator compartment 3 to a cooler is provided.

The cooler chamber 9 partitioned by the partition partition 13 is arrange | positioned behind the freezer compartment 2, The cooler 10, the defrost heater 11, and the cold air circulation fan 12 in this cooler chamber 9 are arranged. Is installed. In the present embodiment, the defrost heater 11 is disposed below the cooler 10, and the return cool air introduced from below in the cooler chamber 9 is transferred upward by the cold air circulation fan 12 disposed above the cooler. do. The cold air conveyed upward is cooled by the cooler 10 and taken out from the cold air blower outlet 14 provided in the partition partition 13 to the freezing chamber 2.

An aluminum upper cover (roof) 15 is provided between the defrost heater 11 and the cooler 10. The upper cover 15 is installed to prevent defrost water dropped from the cooler 10 directly contacting the defrost heater 11 when the frost attached to the cooler 10 is melted by the heat of the defrost heater 11. have. Usually, the glass tube 11a (refer FIG. 3) of the defrost heater 11 turns into the temperature of 500 degreeC from surface temperature at the time of the defrost heater 11 heat generation. Dropping water directly onto the glass tube 11a causes an explosion state of water vapor, which is loud enough to be heard to the outside of the refrigerator, thereby giving anxiety to the user. Preventing this is the role of the top cover 15.

The heat radiating member is arrange | positioned at the outer periphery of the glass tube 11a of the defrost heater 11. In this embodiment, a fin-shaped aluminum heat dissipation fin is wound around the outer circumference of the glass tube 11a. The heat dissipation fin 16 is wound around a strip-shaped thin plate in a coil shape as shown in FIG. This strip-shaped thin plate is a thin, long, thin rectangular plate material, and is dimpled with a dimple-shaped unevenness in advance on the long side of the inner diameter side when molded into the coil shape. The long side on the throttled side is brought into contact with a rod-shaped forming contact member having an outer diameter approximately the same as that of the glass tube 11a or slightly larger than that, and continuously wound into a coil shape. It is taken and cut to predetermined dimension and formed. And it is formed by passing this completed spiral pin through the glass tube 11a. In addition, in the present embodiment, the difference in curvature appears in the long side that becomes the inner diameter and the long side that becomes the outer diameter when molded into a spiral shape, and when winding up without any consciousness, the crack enters the long side of the outer diameter or unconsciously. There is a problem that the site is bent. In the present embodiment, the inner side is throttled to cope with the difference in curvature. However, the aforementioned problem can be solved even by inserting a slit on the outer peripheral side. However, in the present embodiment, the heat dissipation amount of the portion close to the glass tube is also increased by employing a structure for throttling the inner side.

Since the diameter of the glass tube 11a in the present Example is 10.5 mm, the diameter of the contact member for shaping | molding which wound the strip-shaped thin plate was 11.1 mm. As a result, the center hole 16a of the heat radiation fin 16 wound in the coil shape can be molded to about 11.1 mm, and can easily penetrate into the 10.5 mm glass tube 11a.

This spiral heat dissipation fin 16 is also used in place of a conventional protection plate. That is, even if the glass tube 11a may be broken by some impact, even if the glass tube 11a collapses, the heat-dissipation fin 16 which has the shape wound around the longitudinal direction of the glass tube 11a will not collapse the glass tube 11a. Since the degree of prevention is prevented, the heater wire 11b is held in the glass tube, so that even if the glass tube 11a is broken, it can be prevented from dropping down the heater wire 11b. In addition, in the present embodiment, the rigidity of the upper cover 15 described above assists this operation.

Next, the defrost heater 11 is demonstrated based on FIG. The defrost heater 11 is comprised by arrange | positioning the heater wire 11b in the glass tube 11a of an outer diameter of 10.5 mm, and an inner diameter of 8.5 mm, and covering the both ends of this glass tube 11a with the rubber stopper 17. As shown in FIG. Reference numeral 18 is a positioning member.

The both ends of the heater wire 11b are connected to the lead wire 19, and the connection member 21 which connects the linear part 11c of the heater wire 11b and the lead wire 19 is arrange | positioned at the connection part. In this defrost heater 11, the heater wire 11b which wound the nichrome wire of 0.5 mm of wire diameters in coil shape of the outer diameter of 7.5 mm is inserted in the glass tube 11a of diameter 10.5 mm and thickness 1mm. In addition, as shown in the figure, the outer diameter of the partition plate 18 is formed larger than the inner diameter of the glass tube 11a, and the center part is bent vertically toward the inner side of the glass tube 11a, leaving a center part substantially. The connection member 21 is arrange | positioned at this vertical bending part (the vertical bending part itself may be used as the connection member 21, and the connection member 21 may be fixed to the vertical bending part), where the lead wire 19 and The straight portion 11c is connected. When the length of the glass tube 11a and the length of the heater wire 11b are determined, since the partition plate 18 does not lead into the glass tube 11a, the position of the heater wire 11b is determined. Moreover, the both ends of the glass tube 11a are sealed by the rubber stopper 17. As shown in FIG.

Moreover, as shown in FIG. 3, the coil part of the heater wire 11b wound by the coil shape has the straight part 11c formed in linear form. This is to prevent the rubber stopper 17 from being damaged by the heat generated by the heater wire 11b. The rubber stopper 17 is made of a material having high heat resistance characteristics such as silicone rubber, but the heat resistance temperature of the rubber stopper 17 is also usually 145 ° C or lower. By the way, the temperature of the coil part of the heater wire 11b becomes 500 degreeC from the heater wire surface temperature rather than in the glass tube 11a, etc., and is much higher than the heat-resistant temperature of the rubber stopper 17. FIG. When this heat is transferred to the rubber stopper 17 at the temperature in that state through the air in the glass tube, the rubber stopper 17 is damaged by high heat. However, the linear portion 11c does not reach 500 ° C because the amount of heat generated is inherently small. For this reason, in this embodiment, the straight portions 11c are provided on both sides of the coil portion of the heater wire 11b. By this configuration, the air temperature in the glass tube and the glass tube surface temperature corresponding to the straight portion 11c are lower than the coil portion so that the heat of the hot heater wire 11b and the glass tube 11a is conducted to the rubber stopper 17. I suppress it.

The longer the distance of the straight portion 11c is, the better the effect of preventing heat conduction to the rubber stopper 17 is. However, the longer the distance, the lower the ability of the defrost heater. For this reason, it is set as the distance which considered the heat resistance temperature of the rubber stopper 17, and the heat generation temperature of the heater wire 11b. That is, if this straight part 11c is made long, damage of the rubber stopper 17 by heat will be suppressed reliably, but if this straight part 11c is made too long in the longitudinal length dimension of the limited glass tube 11a, Melting of the frost attached to the cooler 10 in the upper portion of the upper portion is delayed, and the defrosting time becomes long. Therefore, it is usually set to 15 mm to 20 mm.

The heat radiation fin 16 has a function of lowering the heater wire temperature around 500 ° C to around 350 ° C, for example. That is, the heat dissipation fin 16 has a function of lowering the surface temperature of the glass tube 11a to around 300 ° C by heat-exchanging with the glass tube 11a, and the heat dissipation area, heat conduction efficiency, and the like are appropriate values for achieving this action. have. In addition, the temperature of the heater wire 11b falls to around 350 degreeC as a result of the cooling of the heater wire 11b being accelerated | stimulated by the glass tube 11a being cooled by the heat radiation fin 16. As shown in FIG.

On the other hand, the heat radiating fin 16 which heat-exchanged with the glass tube 11a radiates heat to the substantially all area | region of the depth dimension D2 of the cooler 10, as shown in FIG. In other words, the outer diameter of the heat dissipation fin 16 is equal to or greater than the depth dimension L1 of the upper cover 15. The depth dimension D2 of the cooler 10 is set to half or less in relation to the ventilation resistance during the cooling operation. Therefore, although the defrost water from the cooler 10 may drop in the part located outside the lower projection surface of the upper cover 15 of this heat radiation fin 16, the corresponding part of the heat radiation fin 16 is substantially Since it is set as the shape extended perpendicular | vertical to an up-down direction, it can be dripped at the trough 20 side as it is, without accumulating the dropped defrost water.

By using the heat radiation fins 16 as described above, the defrost of the gutter 20 receiving the defrost water or the passages 7 and 8 can be appropriately melted at the time of defrosting, and the defrost of the cooler 10 can be shortened. have. That is, it can be said that the heat dissipation fin 16 sets the direction to guide the heating wire to the trough 20 and the passages 7, 8.

In the refrigerator having such a configuration, when the amount of frost deposited on the cooler 10 is increased, heat transfer to air that exchanges heat with the surface of the cooler 10 is inhibited, and the ventilation resistance is increased. The refrigerator detecting this starts energizing the defrost heater 11.

When the electricity supply to the heater wire 11b starts, it radiates a heat wire from the heater wire 11b to the cooler 10 and peripheral components through the glass tube 11a and the heat radiation fin 16. Thereby, the frost adhering to the cooler 10, the trough 20, etc. is melted by defrost water.

Since the defrost heater 11 in this embodiment which wound such a heat radiation fin 16 has attached the heat radiation fin which is equal to or larger than the upper cover L1 with respect to the thin glass tube 11a, it is a cooler. (10) The lower end is heated in a wide range. As a result, the defrosting time can be shortened.

In addition, the outer diameter D3 of the heat dissipation fin 16 is 29 mm. This is a value when the depth dimension D2 of the cooler is 60 mm, and the heat dissipation fin 16 is preferably set to 1/2 or less of the depth dimension D2 of the cooler as a target. This is to prevent the defrost heater 11 becomes a resistance of the flow of wind.

At the same time, even when the glass tube 11a is broken, the heat dissipation fin 16 is attached to the outer circumference of the glass tube 11a and the rubber stoppers are fixedly attached to the upper cover (to be described later). Is supported by the upper cover and the glass tube 11a is not inclined, so that the draped down heater wire does not damage surrounding components. In addition, when the glass tube 11a is broken, problems such as leakage of electricity as in the conventional metal part of the refrigerator main body 1 are eliminated.

Or the clearance gap between the heater wire and the glass tube wound by the coil shape is made into 0.5 mm or less. For this reason, the calorific value per unit length of a heater wire can be lowered compared with the case larger than 0.5 mm. In addition, collapse of the coil heater wire when the glass tube is broken can be prevented by the inner wall of the glass tube.

(2nd Example)

Next, an embodiment different from the first embodiment will be described with reference to FIGS. 5 and 6. First, in Fig. 5, reference numeral 17 is a rubber stopper, 16 is a heat dissipation fin, and 11a is a glass tube. Since the heat radiating fin 16 is wound so that the edge of the one end part of the width direction may contact the glass tube 11a (the surface of the heat radiating fin 16 orthogonal to the glass tube 11a), the inner diameter side and the outer diameter side are natural as mentioned above. It is necessary to absorb the difference in curvature in. For this reason, the throttle part 16c is provided near the inner side (glass tube side) of the heat radiation fin 16, and the half glass tube side is made in the plane. In this manner, the heat dissipation fins 16 are wound around the glass tube 11a between the rubber stoppers 17 as shown in the figure. In other words, this heat radiation fin 16 is provided in the whole length of the glass tube 11a between the rubber stoppers provided in the both ends of the glass tube 11a.

Reference numeral 16b denotes a bent portion provided at the start and end of the winding of the heat dissipation fin. This bent part 16b is for preventing the edge part which arises at the start and end of winding up to the heat radiation fin from damaging the said rubber stopper 17. FIG. This point differs from the first embodiment.

Of course, since the L2 dimension of this bent part 16b is made smaller than the winding pitch P1 dimension, the winding pitch P1 dimension does not change with this bent part 16b. In addition, this winding pitch P1 is 5 mm-15 mm.

Next, in Fig. 6, reference numeral 11a denotes a glass tube, 11b denotes a heater wire, and 16 denotes a heat radiation fin. As described above, the winding pitch P1 of the heat dissipation fin 16 is 5 to 15 mm.

And the winding pitch P1 and outer diameter dimension of this heat radiation fin 16 are pitches which can ensure the heat dissipation area required for making the glass tube 11a surface temperature near 300 degreeC, and external dimension is also 25-40 mm ( 29 mm) here.

In addition, when the heater wire 11b generates heat, it becomes around 500 degreeC. In order to reduce the temperature of this heater wire 11b to 350 degreeC, it is necessary to reduce the temperature of the glass tube 11a to 300 degreeC. This is realized by the heat radiation fins 16.

Reference numeral P2 in the figure indicates the winding pitch of the heater wire 11b. The temperature of the heater wire 11b can be changed also by changing the winding pitch P2 of this heater wire 11b. However, in the present embodiment, the resistance value of the heater is set so that the temperature of the heater wire 11b is 500 ° C or less.

In addition, the winding direction to the glass tube 11a of the heat radiation fin 16 is reversed from the winding direction of the heater wire 11b wound by the coil shape. That is, it winds up so that both may cross | intersect. This is to prevent the heat dissipation fin 16 and the glass tube 11a from overlapping through the glass tube 11a. When the heat dissipation fin 16 and the heater wire 11b are piled up, the surface of the glass tube 11a is covered by the inner diameter side edge of the heat dissipation fin 16, and it becomes the heat dissipation fin 16 side from the glass tube 11a. This is because heat to be dissipated is reflected at the edge of the heat dissipation fin 16 and returned to the heater line 11b side, resulting in raising the temperature of the heater line 11b.

6 is a diagram schematically illustrating the relationship between the heater wire 11b in the glass tube 11a and the heat dissipation fins 16 outside the glass tube 11a. The line is omitted.

6 is drawn to emphasize that the heater wire 11b and the heat dissipation fin 16 cross each other, and in fact, the pitch P2 of the heater wire 11b is small.

(Third Embodiment)

Next, the attaching method of the glass tube heater 11 is demonstrated using FIG. In the drawing, reference numeral 10 denotes a cooler, 11 a defrost heater, 11a a glass tube, 11b a heater wire, 15 an upper cover, 15a an attachment leg of the upper cover 15, and 15b an engagement leg 15a. Member, 16 is heat dissipation fin, 17 is rubber stopper, 20 is gutter, 20a is drain hole of gutter, 20b is gutter heating metal plate (aluminum plate), 19 is lead wire for supplying heater wire 11b, 20c is for defrosting It is an attachment leg which supports a heater to the trough 20.

The upper cover 15 is made of a thin aluminum plate, and is in contact with the heat dissipation fin 16 in order to perform the heat dissipation action of the glass tube 11a similarly to the heat dissipation fin 16. Of course, the upper cover 15 has a function of preventing the defrost water dropped from the cooler 10 directly contact the glass tube. Moreover, the upper cover 15 has the attachment leg 15a formed by bending both ends of the upper cover 15, and is attached to the rubber stopper 17. As shown in FIG.

This attachment leg 15a consists of two attachment legs separated by two by cutting into about U shape in the bent part as shown in FIG.7 and FIG.8, and attaches to the rubber stopper 17 side. The rubber stopper 17 is sandwiched by inserting from above into the provided attachment groove 17a. And this clamping leg 15a winds up and fastens the clamping legs 15a which protruded below from the lower part of the rubber cap 17 after clamping the rubber cap 17. That is, the fastening attachment member 15b provided in one attachment leg 15a is wound up so that it may be wound up by the other attachment leg. Thereby, the top cover 15 is attached to the rubber stopper 17 firmly and in a rotationally stopped state.

Moreover, the rubber stopper 17 of the said defrost heater 11 is attached to the attachment leg 20c standing upright in the trough 20 (made of synthetic resin), as shown in FIG. Besides the trough 20, even if it is attached by the attachment leg 20c provided in the heat exchanger 10, there is no problem functionally at all. Even if the rubber plug 17 is spherical, for example, the attachment groove 17a provided in the rubber stopper 17 is formed in a square shape, and is structured so that rotation stop with the attachment leg 15a is possible. .

In addition, the stopper 38 shown in FIG. 8 is provided in the upper cover 15. The heat radiation fin 16 may be biased to one side of the glass tube 11a by the elasticity which it has. If the heat dissipation fins 16 are biased, there is a problem that the heat dissipation performance of the portion of the glass tube 11a in which the fins are not concentrated decreases and causes a temperature rise. The cause of the heat dissipation fins 16 to be biased may include conveyance of the refrigerator. For example, when a refrigerator is tilted and conveyed, the stairs of a collective house generate | occur | produce, and the state which is installed in a kitchen after this bias is not solved is assumed after that. In this embodiment, since the stopper 38 is provided on the upper cover 15 near the rubber stopper 17, the heat dissipation fin 16 is prevented from being biased even when the refrigerator is tilted. In addition, the stopper 38 may be attached to the upper cover 15 as a separate component separately from the upper cover 15. In addition, by providing a plurality of stoppers 38, bias can be effectively prevented. In other words, the heat dissipation fin 16 may not move with respect to the glass tube 11a, and may be in any shape.

(Example 4)

Next, an embodiment different from the first embodiment will be described with reference to FIGS. 9 and 10. In the figure, reference numeral 11 denotes a defrost heater, and the defrost heater 11 is composed of a glass tube 11a, a heater wire 11b, a coil end portion 11c, a rubber stopper 17, and the like.

Reference numeral 21 is a connecting member for connecting the coil end portion 11c and the lead wire 19. And this connection member 21 is located in the glass tube 11a. The defrost heater 11 is the same as the first embodiment.

A significant difference from the first embodiment is the heat dissipation member (heat dissipation fin) 22 wound around the outer circumference of the glass tube 11a. This heat dissipation fin 22 is formed by winding a rod-shaped (needle-shaped) member in a coil shape. Since the heat radiation fin 22 cannot take a heat radiation area as compared with the heat radiation fin 16 shown in the first embodiment, the winding pitch is narrow. This winding pitch is within 5 to 15 mm, as described above.

The heat dissipation member 22 cannot increase the heat dissipation source as much as in the first embodiment, but the glass tube 11a is formed by combining the heat generation amount with the heater wire 11b having lowered the heat generation amount to 160 W to 140 W, for example. It is possible to lower the heater wire 11b temperature to a desired temperature. That is, the heat dissipation amount of the heat dissipation fin 22 can be reduced as much as the temperature of the heater wire 11b becomes a heater lower than about 500 degreeC of the heater wire 11b demonstrated in previous embodiment. Thereby, the temperature of the glass tube 11a and the heater wire 11b can be reduced significantly. In addition, even if the glass tube 11a is broken, since the glass tube 11a is prevented from collapsing by the heat radiation fin 22, it can suppress that it falls down the heater wire 11b.

(Example 5)

An embodiment different from the first, second, second, and fourth embodiments will be described with reference to FIGS. 11 and 12. In the figure, reference numeral 23 is a door-shaped upper cover with a heat dissipation member (heat dissipation fin). The horizontal member of the upper cover 23, the so-called ceiling surface 23a, is a member that protects the defrost heater 11 (Fig. 2) from dropping of the defrost water from the cooler. The upper cover 23 has vertical members 23b on both sides that are auxiliary members. The vertical members 23b on both sides form heat radiating fins 24 that radiate heat from the defrost heater 11 (FIG. 2).

That is, the holes 25 through which the defrost heater 11 can be inserted in advance are opened in the vertical members 23b, which are auxiliary members on both sides, and these are bent inward alternately as shown in FIG. The holes 25 are matched and the defrost heater 11 is inserted therethrough. In this way, since the top cover 23 and the heat dissipation fins 24 can be produced by one aluminum plate, the top cover 23 can be utilized as the heat dissipation fins 24, and of course, the heat dissipation fins 24 can be used. Since the window 26 formed after bending is formed as an outlet of the heated air, the heated air is not stored in the door-shaped upper cover 23 and is supplied to the cooler side.

At this time, when the defrost heater 11 was 10.5 mm in diameter, the hole diameter of the hole 25 was formed slightly larger (about 10.7 to 11.5 mm), and the glass tube 11a of the defrost heater 11 was formed in these holes. It is to be able to penetrate to 25 smoothly.

In this embodiment, the cutting slits were placed on both sides of the vertical member 23b, which is an auxiliary member of the door-shaped upper cover 23, and bent inward to form the heat dissipation fins. However, as long as the top cover 23 is used as a part of the heat dissipation fins 24, various shapes may be selected in relation to the heat dissipation area rather than the door shape.

By the configuration as described above, the heat dissipation area of the glass tube 11a is expanded by the heat dissipation fin 24. As a result, the temperature of the glass tube 11a is greatly reduced.

In other words, the temperature of the heater wire 11b is also lowered, so that the rubber stopper 17 (FIG. 3) is not damaged due to heat.

Further, even if the glass tube 11a is broken, the glass tube 11a is supported by the heat dissipation fins 24, so that the glass tube collapses and the heater wire 11b inside the trough 20 (FIG. 2) is lowered. It is effective to suppress the dropping.

Next, with reference to FIGS. 13 and 14, an example in which a defrost heater is used in a refrigerator using a hydrocarbon-based isobutane as a refrigerant will be described. As the defrost heater, any of those shown in the first to fifth embodiments can be used.

14 illustrates a refrigeration cycle. The compressor 26, the condenser 27, the capillary tube 28, and the cooler 29 are connected in series, and are connected annularly, and the refrigeration cycle is comprised. Conventionally, proton refrigerants have been used in terms of stable physical properties and ease of handling of the refrigerants enclosed in the refrigeration cycle.

In recent years, however, development of hydrocarbon refrigerants such as propane (R-290a) and isobutane (R600a), which have little effect on ozone layer destruction or global warming, has been planned. Hereinafter, this hydrocarbon type refrigerant | coolant is called HC refrigerant.

This HC refrigerant is sealed in the refrigeration cycle. When the HC refrigerant is damaged in the welded part of the cooler 29 or the like, it is considered that the HC refrigerant leaks into the refrigerator during the defrosting operation. If the HC refrigerant is filled in the refrigerator, there is a risk of ignition of the HC refrigerant when the defrost heater generates heat.

That is, since the cooler is heated from the defrost heater during the defrosting operation, the isobutane in the cooler 29 becomes a pressure higher than atmospheric pressure (about 3 kg / cm 2) and leaks into the refrigerator. In the cooling operation, isobutane in the cooler becomes negative with respect to atmospheric pressure, and isobutane does not leak into the refrigerator.

Next, in Fig. 14, reference numeral 30 denotes a cold air circulation fan and 31 denotes a defrost heater. The cold air circulation fan 30 circulates the cold air cooled by the cooler 29 forcibly in the freezer compartment or the refrigerating compartment. The defrost heater 31 is for melting the frost when the frost is deposited on the cooler 29, the specific configuration of which is the same as FIG.

In the figure, reference numeral 31 denotes a defrost heater, 31a denotes a glass tube, and 31b denotes a heater wire. This heater wire 31b consists of the coil part a and the coil end part b, and the coil part a is wound by the coil of 7.5 mm of outer diameters when the inner diameter of the glass tube 31a is 8.5 mm. . And this winding pitch is wound up to 2.0 mm or less. When the winding pitch is set to 2.0 mm or less, the temperature rises above the heat generation of the coil portion a of the heater wire 31b itself under the influence of adjacent heater wires.

In the defrost heater 31 having the configuration as described above, the temperature of the glass tube 31a facing the coil portion a rises to the temperature near the heater wire 31b as described in the previous embodiment. In this embodiment, since the coil part a is wound by 7.5 mm of outer diameters, and the inner diameter of the glass tube 31a is 8.5 mm, the temperature of the part of the glass tube 31a which opposes the coil part a becomes a heater. Since the temperature closes to the line 31b, the rubber stopper 32 at both ends is damaged by this heat.

The straight part b of the heater wire 31b points to the part which made the heater wire 31b linear in order to prevent the damage of the rubber stopper 32 of both ends. Since the calorific value of this part is naturally small, the temperature of the part of the glass tube 31a which opposes this straight part b does not reach the temperature of the glass tube 31a equivalent to the coil part a.

However, when the dimension of this straight part b is short, the air temperature in the glass tube and the glass tube 31a are naturally heated by the heat influence of the coil part a. For this reason, it is usually necessary to ensure the L2 dimension of 15 mm or more.

The rubber stopper 32 seals both ends of the glass tube 31a and is made of silicone rubber having heat resistance (for example, 145 ° C).

Reference numeral 33 is a partition plate provided at the glass tube end to position the coil portion a of the heater wire 31b. 34 is a connection member which connects the coil end part b and the lead wire 35, and the position of this connection member 34 is also positioned by the partition plate 33 of the front. Thereby, the L2 dimension of the rubber stopper 32 and the coil part a can be set to a predetermined dimension.

In the refrigerator provided with the defrost heater 31 which has such a structure, when the frost accumulated in the cooler 29 and defrost was needed, the electricity supply to the defrost heater 31 is started. When the electricity supply to this defrost heater is started, when there exists a damage part in the cooler 29 slightly, HC refrigerant leaks from the damage part. Since the ignition temperature of this HC refrigerant, for example, isobutane, is 494 ° C, it is necessary to lower the temperature of the heater wire 31b than this ignition temperature. In the present embodiment, in consideration of further safety, for example, it is set to 394 ℃.

That is, in the present embodiment, the heat radiation fins 36 are provided on the preceding defrost heater 31 (glass tube 31a, heater wire 31b) to be 394 ° C or lower. The heat dissipation fin 36 may be arbitrarily selected from the shapes and forms shown in the first, second and third embodiments. What is needed is a heat dissipation member which is a heat dissipation member (heat dissipation fin) which can lower the temperature of the defrost heater 31, for example, a member whose heat conductivity is higher than the glass tube 31a.

In addition, in this embodiment, it is set as one layer of glass tube other than the double glass tube heater used in consideration of explosion-proof property with respect to a flammable refrigerant. In the one-ply glass tube as described above, the temperature of the glass tube 31a can be reduced by the heat dissipation fin 36, and the air temperature in the glass tube 31a can also be lowered by this action, so that the heater wire provided in the glass tube The rise of the temperature of 31b can be suppressed, and even the temperature of the heater wire 31b can be 394 degrees C or less.

That is, in the case of using a double glass tube, the air between the inner glass tube and the outer glass tube fulfills the role of a heat insulating material. For example, even if a heat dissipation fin is attached, the heater wire temperature cannot be immediately lower than 394 ° C. A method of changing the pitch is required. This embodiment has a structure different from the double glass tube, and since the heat of the heater wire 31b is taken away by the heat radiation fin via the glass tube, the temperature of the glass tube and the heater wire can be 394 ° C or lower. In addition, since the heat of the heater wire 31b is transmitted to the surroundings by the heat radiation fins 36 in this manner, the defrost of the cooler 29 can be performed with a small power consumption.

In addition, although the refrigerator in the Example shown above is a refrigerator provided with a freezer compartment and a refrigerator compartment from the upper part, the refrigerator which concerns on this invention is not limited to this, The refrigerator which arrange | positions a defrost heater in the lower part of a cooler, and has a trough in the lower part. The back surface may be, for example, provided with a revolving door refrigerator compartment, a drawer door vegetable compartment, and a drawer door freezer compartment from the top. In addition, of course, the return flow path of cold air is not limited to the flow path shown in FIG. 1, and there is no problem even in another format, for example, the flow path type returned to the lower side of the cooler.

As described above, the embodiments shown in the first to fifth embodiments have the following effects.

That is, in a refrigerator provided with a heater wire wound in a coil shape in a glass tube and sealed at both ends with a defrost heater sealed at both ends with a rubber stopper, an inner circumference is in contact with or close to the outer circumference of the glass tube. By providing the heat dissipation member (heat dissipation fin) attached so that it may be between rubber stoppers, the heat wire from a heater wire does not return to a defrost heater again. Moreover, since the clearance of the heater wire wound up in the coil shape and the glass tube was 0.5 mm or less, and the heat transfer from the heater wire to the glass tube was made favorable, it is possible to lower the temperature of the heater wire as well as the glass tube temperature. Thereby, the refrigerator which can eliminate the damage etc. of a rubber stopper can be obtained.

In addition, since the upper cover is formed of a thin metal plate such as aluminum, and both end attaching legs of the upper cover are provided on the rubber stopper, even if the glass tube is broken, the upper cover member becomes a core material and the glass tube is broken. It can be prevented from buckling and deforming to V shape, for example.

In addition, after the rubber stopper was clamped using the attachment leg formed by bending both ends of the upper cover as two separate attachment legs, the fastening attachment member provided on one side of the attachment leg was fastened to the other attachment leg. The upper cover and the rubber stopper are secured, and when the glass tube is broken, the upper cover can prevent the glass tube from buckling through the rubber stopper.

In addition, the strip-shaped thin plate forming the heat dissipation member is wound in a glass tube to form a heat dissipation portion (heat dissipation fin), and the winding direction of the heat dissipation fin to the glass tube is reversed to the winding direction of the heater wire wound in the coil shape. The heater wire and the heat dissipation fin are stacked so that the heat dissipation of the heater wire is not impaired.

In addition, since the heat transfer from the glass tube to the heat radiation fin was made good by setting the gap between the heat radiation fin such as aluminum and the glass tube wound on the glass tube to 0.1 to 0.5 mm, the heat radiation fin can be easily assembled into the glass tube. The heat transfer from the glass tube to the heat dissipation fin is also performed well.

Moreover, since the longitudinal direction of the defrost heater was provided in the width direction of the cooler, and the outer diameter of the aluminum radiating fin was made 1/2 or less of the thickness of the cooler, it was sucked from the lower part of the defrost heater and passed to the cooler via this defrost heater. It does not interfere with cold air being inhaled.

In addition, since the end of the aluminum heat dissipation fin is bent to the opposite side to the rubber cap so as not to contact the rubber cap sealing the glass tube end, the rubber stopper is not damaged by the heat dissipation fin.

The top cover and the heat dissipation fin are coated or anodized to promote endothermic action, and the heat of the heater wire, including the glass tube, is efficiently radiated to the cooler side through the heat dissipation fin.

In addition, since the side of the band-shaped thin metal plate is in contact with the glass tube and the other side is flat, the metal plate having a different curvature can be wound into the glass tube, and the area of the heat dissipation fin portion near the glass tube can be expanded. will be.

In addition, a heater wire having a coil (winding capacity) capable of raising the temperature to the vicinity of the ignition temperature of the HC refrigerant (large heat capacity) is built in the glass tube, and a defrost heater with both ends sealed with a rubber stopper is installed under the cooler. As a refrigerator using hydrocarbon-based isobutane as a heat-dissipating member (heat dissipation fin) having a heat dissipation effect of suppressing the surface temperature and the heater wire temperature of the glass tube constituting the defrost heater below the set temperature, the normal defrost During operation, most of the heat generated by the heater wire can be supplied to the frost as a heat capacity rather than as a temperature, and even if the HC refrigerant leaks from the damaged part of the cooler, etc., the temperature rise of the heater wire of the HC refrigerant is suppressed. It doesn't work. In addition, the use of the top cover as a member of the heat dissipation member can further increase the heat dissipation capacity.

The winding direction of the heat radiation member (heat radiating fin) is different from the winding direction of the heater wire in order to set the temperature at the time of heat generation of the defrost heater to 394 ° C., which is minus 100 ° C., from 494 ° C. of the ignition point temperature of hydrocarbon-based isobutane. Since it is reversed, a defrost heater does not become a ignition source of HC refrigerant.

According to this invention, the refrigerator which suppressed the damage of the rubber stopper which seals the glass tube end part of a defrost heater from being damaged by heat can be provided.

According to the present invention, in a refrigerator using a hydrocarbon-based refrigerant as a refrigerant, it is possible to provide a refrigerator which prevents ignition by a defrost heater while suppressing a decrease in defrosting performance even if a refrigerant leaks in the refrigerator.

Claims (10)

A refrigerator having a heater wire disposed in a lower portion of a cooler and wound in a coil shape disposed in a glass tube and having a rubber stopper for sealing both ends of the glass tube, wherein the refrigerator is provided between the rubber stoppers, and an inner circumference is provided between the glass stoppers. A heat dissipation member attached to or in contact with an outer circumference, the gap between the heater wire wound in the coil shape and the glass tube to be 0.5 mm or less, formed of a thin metal plate, installed on the upper portion of the glass tube, Refrigerator with attached top cover. delete The two sides of the attachment leg formed by bending both ends of the upper cover and the fastening member provided on one side of the attachment leg by sandwiching the rubber stopper by the attachment leg. One refrigerator to fasten to the attachment leg of the. The refrigerator according to claim 1, wherein the heat dissipation member is a heat dissipation fin obtained by winding a strip-shaped thin plate into a glass tube in a coil shape, and the winding direction of the heat dissipation fin into the glass tube and the winding direction of the heater wire are reversed. A refrigerator having a heater wire disposed in a lower portion of a cooler and wound in a coil shape disposed in a glass tube, and a defrost heater having a rubber stopper for sealing both ends of the glass tube, wherein the refrigerator is provided between the rubber stoppers and has an inner circumference formed therein. And a heat dissipation member attached to or in contact with the heat dissipation member, wherein the heat dissipation member is a heat dissipation fin wound around a glass tube in a coil shape with a strip-shaped sheet, and the gap between the heat dissipation fin and the glass tube is 0.1 to 0.5 mm. And a top cover formed on the upper portion of the glass tube and attached to the rubber stopper. A refrigerator having a defrost heater having a heater wire which is a lower part of a cooler and has a heater wire wound in a coil shape arranged in a glass tube in a longitudinal direction thereof in a width direction thereof, and a rubber stopper sealing both ends of the glass tube, wherein the rubber stopper is provided. And a heat dissipation member provided between the inner circumferences to be in contact with or close to the outer circumference of the glass tube, wherein the heat dissipation member is a heat dissipation fin wound around the glass tube in a coil shape with a strip-shaped sheet, Made in less than 1/2 of the refrigerator. A refrigerator having a defrost heater having a heater wire which is a lower part of a cooler and has a heater wire wound in a coil shape arranged in a glass tube in a longitudinal direction thereof in a width direction thereof, and a rubber stopper sealing both ends of the glass tube, wherein the rubber stopper is provided. And a heat dissipation member disposed between the inner circumferences or in contact with or adjacent to the outer circumference of the glass tube, wherein the heat dissipation member is a heat dissipation fin wound around the glass tube in a coil shape with a strip-shaped sheet, and an end of the heat dissipation fin is the rubber stopper. Refrigerator bent to the opposite side to the rubber stopper so as not to touch. The refrigerator according to claim 1, wherein the upper cover and the heat dissipation member are anodized. A refrigerator having a defrost heater having a heater wire which is a lower part of a cooler and has a heater wire wound in a coil shape arranged in a glass tube in a longitudinal direction thereof in a width direction thereof, and a rubber stopper sealing both ends of the glass tube, wherein the rubber stopper is provided. And a heat dissipation member disposed between the inner circumferences of the glass tube and the inner circumference of the glass tube, wherein the heat dissipation member is a heat dissipation fin wound around the glass tube in a coil shape, and the heat dissipation fin is a side in contact with the glass tube. The side of the refrigerator is throttled and the other side is flat. A refrigerator having a defrost heater having a heater wire disposed in a lower portion of a cooler through which a hydrocarbon-based refrigerant flows and wound in a coil shape disposed in a glass tube, and a rubber stopper for sealing both ends of the glass tube. And a heat dissipation member provided between the stoppers and attached so that the inner circumference is in contact with or close to the outer circumference of the glass tube, and the heater wire has the ability to rise in temperature near the ignition temperature of the coolant, And said heat dissipation member is selected so that the temperature of a heater wire is lower than the ignition temperature of said refrigerant, and is formed of a thin metal plate and is provided on an upper portion of said glass tube and has an upper cover attached to said rubber stopper.

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