JP2006112638A - Refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem found when a glass tube is broken that a heater wire in the glass tube hangs and is brought into contact with a trough, which causes electric leakage and has harmful effects on a control board or the like. <P>SOLUTION: This refrigerator comprises a cooler, a defrosting heater mounted on a lower part of the cooler for removing frost attached to the cooler, a heat radiating member mounted on an outer periphery of the defrosting heater, the trough mounted on a lower part of the defrosting heater for receiving defrost water dropped from the cooler, and an upper cover mounted on an upper part of the defrosting heater for protecting the defrosting heater from the defrost water dropped from the cooler. The defrosting heater has the glass tube, the heater wire incorporated in the glass tube and rubber plugs for sealing both ends of the glass tube, and both ends of the upper cover are fixed to the rubber plugs. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a refrigerator provided with a defrosting heater for defrosting frost adhering to a cooler of a refrigeration cycle.

  As a prior art regarding the refrigerator provided with the defrost heater, there exists a thing of patent document 1, for example. In this example, a defrosting tube heater in which a coil of nichrome wire is covered with a glass tube is provided below the cooler. This defrosting tube heater defrosts the frost adhering to the cooler. An upper cover is provided between the cooler and the defrosting tube heater so as to cover the defrosting tube heater, and the defrosting water dripping from the cooler is in direct contact with the defrosting tube heater. Is preventing. In addition, a bottom that is electrically insulated and held is provided between the defrosting tube heater and the lower ridge so as to protect the ridge. It prevents dripping down the heel and damaging the heel, and prevents leakage through defrost water.

  In Patent Document 2, a heater wire is provided in a sheath tube that is filled and sealed with an insulating material so that the defrost heater temperature is lower than the isobutane ignition temperature of the refrigerant, and a heat transfer promoting fin is provided on the outer periphery of the sheath tube. A defrost heater is described.

JP-A-8-54172

JP 2000-283635 A

  Hereinafter, problems in the conventional technology will be described.

  First, the structure of the refrigerator is shown. FIG. 18 is a view showing a conventional refrigerator. In FIG. 18, reference numeral 51 denotes a refrigerator main body. The refrigerator main body 51 includes a freezer compartment 52 and a refrigerator compartment 53 therein, and is provided with a partition wall 56 that divides between them. A freezer compartment door 54 that closes the opening is provided at the front opening of the freezer compartment 52, and a refrigerating compartment door 55 that closes the opening is provided at the front opening of the refrigerating compartment 53.

  The partition wall 56 is provided with a passage 57 for returning cold air heat-exchanged with food in the freezer compartment 52 to a cooler described later and a passage 58 for returning cold air heat-exchanged with food in the refrigerator compartment 53 to the cooler. Yes. A cooler chamber 59 communicating with the freezer compartment 52 and the refrigerator compartment 53 via the passage 57 and the passage 58 is provided at the back of the freezer compartment 52. The cooler chamber 59 includes a cooler 60 and a defrost heater. 61, a cold air circulation fan 62 is provided. A partition 63 is provided between the cooler chamber 59 and the freezer compartment, and a cool air outlet 64 is formed in the partition 63. With these configurations, the cold air cooled by exchanging heat with the cooler 60 is blown out from the cold air outlet 64 to the freezer compartment 52 by the cold air circulation fan 62.

  An aluminum upper cover 65 is provided between the defrost heater 61 and the cooler 60, and when the frost adhering to the cooler 60 is melted by the heat of the defrost heater, the defrost water directly enters the defrost heater. This is prevented.

  Usually, the glass tube 61a of the defrost heater has a surface temperature around 500 ° C. during defrosting. For this reason, when a water droplet directly drops on the glass tube during defrosting, a steam explosion state is exhibited and a loud sound is generated. If it is in a state close to such a steam explosion state, the generated sound becomes a sound that can be heard to the outside of the refrigerator, giving anxiety to the user. It is the role of the upper cover 65 to prevent this.

  A protective plate 66 made of aluminum is installed in the lower part of the defrosting heater 61. This protective plate 66 is a resin cage that drains defrosted water outside the chamber when the glass tube 61a is broken by an impact or the like. 67 is protected. FIG. 19 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 hanging down and touching the flange 67. Since the aluminum protective plate 66 is insulated and held, even if the heater wire 61b hangs down on the protective plate 66, electricity leaks to the metal part of the refrigerator main body 51. There is nothing.

  When the freezer compartment 52 or the refrigerator compartment 53 is cooled, the refrigerant is passed through the cooler 60 to cool the cooler 60. At the same time, by the action of the cold air circulation fan 62 that is operated, the cold air cooled by exchanging heat with the cooler 60 is blown out from the cold air outlet 64 to the freezer compartment 52. The cold air blown into the freezer compartment 52 cools the frozen food in the freezer compartment 52 and is returned to the cooler 60 and the defrost heater 61 through the passage 57 again. On the other hand, on the side of the refrigerating room 53, the cold air cooled by the cooler 60 is blown out to the refrigerating room 53 by a cold air circulation fan 62 using a cooling passage dedicated to the refrigerator (not shown). Again, refrigerated food is cooled by heat exchange with refrigerated food. The cooled cool air returns to the cooler 60 and the defrost heater 61 through the passage 58.

  The air that exchanges heat with the cooler 60 is air that has become highly humid due to the inflow of outside air by opening and closing the freezer compartment door 54 and the refrigerator compartment door 55, evaporation of moisture contained in food in the freezer compartment 52 and the refrigerator compartment 53, and the like. Therefore, the moisture forms frost and accumulates in the cooler 60. As the amount of deposition increases, heat transfer between the surface of the cooler 60 and the air that exchanges heat is hindered, and airflow resistance is reduced, resulting in a decrease in the air volume. As a result, the heat passage rate is lowered and insufficient cooling occurs.

  Therefore, energization of the defrosting heater 61 is started before this insufficient cooling occurs. When energization of the heater wire 61b is started, heat rays are radiated from the heater wire 61b to the cooler 60 and peripheral components through the glass tube 61a. At this time, the heat rays radiated to the protection plate 66 are partially reflected from the shape of the protection plate 66 to the heater wire 61b through the glass tube 61a. Further, a part of the defrost water melted by the heat from the defrost heater falls directly on the rod 67 and the other falls on the upper cover 65. Since the upper cover 65 has a lower temperature than the glass tube 61a, the steam explosion does not occur here.

In general, the surface temperature of the glass tube 61a is extremely high, not to mention the surface of the heater wire 61b of the defrosting heater 61. This is because the protection plate 66 is in the vicinity of the defrosting heater 61, and the heat rays once radiated through the glass tube are reflected by the protection plate 66, and the glass tube 61a naturally heats the heater wire 61b abnormally. It is.
As a result, the rubber plug that seals both ends of the defrost heater 61 may be damaged by heat.

  Further, if a coil end portion (a straight portion twisted by folding the heater wire 61b with a predetermined length) is formed at the end of the heater wire to protect the rubber plug from damage, the coil end portion There was a problem that the melting of the frost on the upper cooler 60 was delayed and the defrosting time was increased.

Furthermore, since the defrost heater 61 having the shape shown in the figure is as small as ¼ to 如 く as shown in FIG. 20 with respect to the depth dimension D1 of the cooler 60, the heat rays spread to the entire depth D1 of the cooler 60. There was a problem that the defrosting time was delayed.
In FIG. 19, 68 is a lead wire for supplying power to the heater wire 61b, 69 is a fitting for connecting the lead wire 68 and the heater wire 61b, and 70 is a rubber plug for sealing both ends of the glass tube 61a. , 71 indicate holes through which the lead wires 68 provided in the rubber plug 70 are passed.
Moreover, when it was set as the structure which covers a heater wire with an insulating material like the patent document 2, there existed the following problems. When the heater wire is energized, since the heater wire generates heat, not only the sheath tube but also the insulating material itself covering the heater wire is heated. In Patent Document 2, since both ends of the sheath tube are sealed with caps, heat is transferred to the cap via the insulating material when the periphery of the heater wire is covered with the insulating material. At this time, even if a cap having a high heat resistance such as silicon rubber is used, the heat resistant temperature is about 145 ° C. If the temperature is higher than the heat resistant temperature, the cap is damaged. In that case, it is necessary to separately provide a heat insulating member between the insulating material and the cap.

  Moreover, when the heat generation temperature of the heater wire is set low, the output as the defrost heater is lowered, and the performance as the defrost heater is lowered. On the other hand, if an insulating material having an excellent heat insulating property is used, the temperature of the heater wire cannot be transmitted to the outside, and this also leads to a decrease in performance as a defrosting heater.

  Moreover, since the defrosting heater itself is disposed in the vicinity of the cooler, the ambient temperature is −30 ° C. or lower during normal operation of the refrigerator. Although the heater wire is several hundred degrees during the defrosting operation, the expansion and contraction of the insulating material with respect to these temperature changes was not considered.

Further, in Patent Document 2, a heat transfer promoting fin is provided on the outer periphery of the sheath tube. However, when the sheath tube is broken, the heater wire in the sheath tube hangs down and comes into contact with the heel to cause electric leakage, thereby causing a control board. There was a drawback that adversely affected the above. The fins for heat transfer promotion are merely provided on the outer periphery of the sheath tube, and when the sheath tube is broken, the fin is inclined together with the broken sheath tube.
This invention is made | formed in view of the above-mentioned subject by using a combustible refrigerant | coolant, and it aims at providing the refrigerator which aimed at the improvement of safety and efficiency.

In order to achieve the above object, the present invention is characterized in that a cooler, a defrost heater provided below the cooler for defrosting frost attached to the cooler, and an outer periphery of the defrost heater A heat dissipating member provided on the defrosting heater, a bowl for receiving the defrosting water provided below the defrosting heater and falling from the cooler, and the defrosting water provided above the defrosting heater and falling from the cooler. An upper cover for protecting the frost heater, the defrost heater having a glass tube, a heater wire built in the glass tube, and a rubber plug for sealing both ends of the glass tube, Both ends of the cover are fixed to the rubber stopper. With this configuration, the glass tube does not tilt even when the glass tube is broken, so that the heater wire hanging from the glass tube is not damaged.
Further, bending of the glass tube between the rubber plugs can be prevented by the rigidity of the upper cover made of a metal such as aluminum.
In addition, since a supporting member for preventing the glass tube from being bent is provided at the lower part of the heat radiating member via the heat radiating fin, the defrosting heater that breaks and breaks the glass tube is provided with the upper cover and the supporting member. And the glass tube keeps the straight state.
Further, the support member has a wire shape fixed to the rubber stopper, and prevents the heat radiation fin from collapsing when the glass tube is broken. Moreover, since this support member is a wire-like thing, the heat ray which contacted the wire-like support member is returned in a glass tube, and a glass tube internal temperature and a heater wire temperature are not raised abnormally.
Moreover, the strip-shaped thin plate forming the heat radiating member is wound around the glass tube in a coil shape to constitute a heat radiating fin, and the winding direction of the heat radiating fin around the glass tube is reversed to the winding direction of the heater wire wound in the coil shape. Therefore, the heater wire and the heat radiating fin overlap, and the heat radiating of the heater wire is not hindered by the heat radiating fin.
In addition, since the mounting leg that fits and supports the rubber plug of the defrost heater has a holding portion in which the rubber plug is not inclined even when the glass tube is broken, the glass tube is accompanied by the rigid support of the upper cover. At the time of bending, the glass tube is inclined and does not hang down the heater wire.

  According to the present invention, since the glass tube does not tilt even when the glass tube is broken, the heater wire hanging from the glass tube is not damaged.

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

  FIG. 1 is a longitudinal 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 an AA sectional view of the defrosting heater of FIG. It is a heat sink fin perspective view in FIG. FIG. 5 is an enlarged perspective view of a main part of the defrost heater for explaining an embodiment different from FIG. 3, and FIG. 6 is a view for explaining the winding direction of the heat radiation fin and the heater wire of the defrost heater equipped with the present invention. It is. 7 is a view showing the relationship between the defrost heater and the soot as seen from the direction of arrow P in FIG. 5, and FIG. 8 is a view showing another embodiment corresponding to the AA cross-sectional view of FIG. It is. FIG. 9 is a view showing a method for fixing the upper cover 15 and the rubber plug 17, and FIG. 10 is a view for explaining the movement of the defrost heater when the glass tube of the defrost heater is broken for explaining the present invention. 11 is an improved product of the mounting leg 20c of FIG. 8, FIG. 12 is a view showing a fastening relationship between the rubber stopper and the upper cover, and FIG. 13 is a cross-sectional view taken along the line BB of FIG. 14 is a view showing an embodiment different from FIG. 12, FIG. 15 is a sectional view taken along the line CC in FIG. 14, and FIG. 16 is a view for explaining the winding pitch of the defrost heater, etc. These are explanatory drawings of the refrigerating cycle provided with this invention.

  First, the structure of the refrigerator will be described with reference to FIGS. The refrigerator main body 1 has a freezer compartment 2 and a refrigerator compartment 3 inside. A freezer compartment door 4 that closes the opening is provided in front of the freezer compartment 2, and a refrigerator compartment door 5 that closes the opening is provided in front of the refrigerator compartment 3. A partition wall 6 is provided between the freezer compartment 2 and the refrigerating compartment 3, and a passage for returning cold air heat-exchanged with food in the freezer compartment 2 to a cooler described later is provided in the partition wall 6. 7 and a passage 8 for returning the cold air heat-exchanged with the food in the refrigerator compartment 3 to the cooler.

  A cooler chamber 9 partitioned by a partition 13 is disposed at the back of the freezer compartment 2, and a cooler 10, a defrost heater 11, and a cool air circulation fan 12 are provided in the cooler chamber 9. In the present embodiment, the defrost heater 11 is disposed below the cooler 10, and the return cold air flowing from the lower side of the cooler chamber 9 is sent upward by the cool air circulation fan 12 disposed above the cooler. It is done. The cold air sent upward is cooled by the cooler 10 and blown out into the freezer compartment 2 through the cold air outlet 14 provided in the partition 13.

  An upper cover 15 made of aluminum is provided between the defrost heater 11 and the cooler 10. The upper cover 15 prevents the defrost water dripped from the cooler 10 from being directly applied to the defrost heater 11 when the frost attached to the cooler 10 is melted by the heat of the defrost heater 11. Usually, the glass tube 11a (see FIG. 3) of the defrost heater 11 has a surface temperature around 500 ° C. when the defrost heater 11 generates heat. When a water drop directly drops on the glass tube 11a, a loud steam explosion occurs and the sound leaks to the outside of the refrigerator, giving the user anxiety. It is the role of the upper cover 15 to prevent this.

  A heat radiating member is disposed on the outer periphery of the glass tube 11 a of the defrost heater 11. In the present embodiment, the fin-shaped aluminum radiating fin is wound around the outer periphery of the glass tube 11a in a coil shape (spiral shape). As shown in FIG. 4, the heat dissipating fin 16 as a heat dissipating member is formed by continuously forming a strip-like thin plate in a coil shape on a molding pad (employment) having an outer diameter substantially the same as or slightly larger than that of the glass tube 11a. And is formed by cutting it into a predetermined dimension. And the glass tube 11a is passed through the center hole 16a of the coil-shaped heat radiation fin 16 formed in this way. In addition, when winding a strip | belt-shaped thin plate in a coil shape, a wrinkle will arise on the inner side from the difference in curvature with the inner side in the position near the glass tube 11a, and the outer side in the position far from the glass tube 11a. In order to prevent this, it is necessary to deal with the difference in curvature by applying a process such as slitting the outside or narrowing the inside. In the case of the present embodiment, a structure in which the inner side is narrowed is adopted to increase the heat radiation amount in a portion close to the glass tube.

  Since the diameter of the glass tube 11a in this embodiment is 10.5 mm, the diameter of the molding material (employment) around which the strip-shaped thin plate is wound is set to 11.1 mm. As a result, the center hole 16a of the radiating fin 16 wound in a coil shape can be formed to 11.1 mm and can be easily inserted into the 10.5 mm glass tube 11a.

  Thus, the heat dissipating fins 16 serve as a substitute for the conventional protective plate. That is, even if the glass tube 11a may be broken by some impact, the radiating fins 16 that are wound around the longitudinal direction of the glass tube 11a have the glass tube 11a even if the glass tube 11a collapses. The heater wire 11b is held in the glass tube so that the heater wire 11b does not sag even if the glass tube 11a is broken as in the prior art. In the present invention, the rigidity of the upper cover 15 described above assists this function as will be described later.

  Next, the defrosting heater 11 will be described with reference to FIG. This defrost heater 11 is provided with a heater wire 11b in a glass tube 11a having an outer diameter of 10.5 mm and an inner diameter of 8.5 mm, and a rubber plug 17 is provided so as to cover both ends of the glass tube. Reference numeral 18 denotes a positioning member that abuts against the end of the glass tube 11a and prevents the heater wire 11b from being pulled into the glass tube 11a more than necessary.

  Both ends of the heater wire 11b are connected to the lead wire 19, and a connecting fitting 21 for connecting the straight portion 11c of the heater wire 11b and the lead wire 19 is disposed at the connecting portion. This defrosting heater 11 has a positioning member as shown in the figure, in which a heater wire 11b in which a nichrome wire having a wire diameter of 0.5 mm is wound in a coil shape having an outer diameter of 7.5 mm in a glass tube having a diameter of 10.5 mm and a wall thickness of 1 mm. 18, and both ends of the glass tube 11 a are sealed with rubber plugs 17.

  In addition, as shown in FIG. 3, it has the linear part 11c formed in linear form on both sides of the coil part of the heater wire 11b wound in the coil shape. When the straight portion 11c and the coil portion are placed with the same distance from the glass tube 11a, the distance of the heater wire 11b at a predetermined distance of the glass tube 11a is shorter in the straight portion 11c than in the coil portion. It can be suppressed. For this reason, it is possible to prevent the rubber plug 17 from being damaged by the heat generated by the heater wire 11b.

  The rubber plug 17 is usually made of a material having high heat resistance such as silicon rubber, and the heat resistance temperature of the rubber plug 17 is usually 145 ° C. or lower. However, the temperature of the coil portion of the heater wire 11b is 500 ° C. in terms of the heater wire surface temperature, which is much higher than the heat resistance temperature of the rubber plug 17, because it is in the glass tube 11a. If this heat is transmitted to the rubber plug 17 at the same temperature, the rubber plug 17 is damaged by high heat. Therefore, by forming the straight portion 11c as in the present embodiment, the amount of heat generation can be suppressed, and the temperature not reaching 500 ° C. can be achieved. Therefore, in this embodiment, the straight portions 11c are provided on both sides of the coil portion of the heater wire 11b. With this configuration, it is possible to prevent the heat of the heater wire 11b and the glass tube 11a from being conducted to the rubber plug 17.

  The longer the distance of the straight portion 11c, the more effective it is to prevent heat conduction to the rubber plug 17. However, if the distance is increased too much, the defrosting heater performance will be reduced. The distance is set in consideration of the heat generation temperature of the heater wire 11b. That is, it is possible to prevent the rubber plug 17 from being damaged by heat if the straight portion 11c is made long. However, if the straight portion 11c is made long within a limited size, the cooler 10 at the upper portion of the straight portion is used. Melting of the frost that arrives at the lag will be delayed, and the defrosting time will become longer. Therefore, it is normally set to 15 mm to 20 mm.

  The radiating fins 16 have a function of reducing the heater wire temperature around 500 ° C. to, for example, around 350 ° C. That is, the radiating fin 16 is a radiating fin having a good heat radiating area and heat conduction efficiency that can reduce the surface temperature of the glass tube 11a to around 300 ° C. by exchanging heat with the glass tube 11a. As a result, the temperature of the heater wire 11b is cooled by the glass tube 11a and decreases to around 350 ° C.

  On the other hand, the radiation fins 16 that have exchanged heat with the glass tube 11a radiate heat to the entire depth dimension D2 of the cooler 10 as shown in FIG. In other words, the outer diameter of the radiating fin 16 is equal to or larger than L1 of the upper cover 15.

  Further, the depth dimension D2 of the cooler 10 may be less than half in relation to the ventilation resistance during the cooling operation. Therefore, although the defrost water from the cooler 10 may be dripped at a portion of the radiating fin 16 outside the lower projection surface of the upper cover 15, the portion of the radiating fin 16 is substantially in the vertical direction. Since it has an extended shape, the defrosted water that has been dropped is dropped directly onto the heel 20 side without accumulating.

  In addition, by using the radiating fins 16, it is suitable for melting the frost attached to the eaves 20 receiving the defrost water or the passages 7, 8 at the time of defrosting. It can be shortened. In other words, the radiating fins 16 direct the heat source to the eaves 20 and the passages 7 and 8.

  In the refrigerator having such a configuration, when the amount of frost accumulated on the cooler 10 increases, heat transfer between the surface of the cooler 10 and the air that exchanges heat is inhibited, and the ventilation resistance increases. The refrigerator that has detected this starts energization to the defrosting heater 11.

  When energization of the heater wire 11b is started, heat rays are radiated from the heater wire 11b to the cooler 10 and peripheral components through the glass tube 11a and the heat radiation fins 16. Thereby, the frost which arrived at the cooler 10 or the basket 20 etc. is melt | dissolved in defrost water.

  At this time, the defrosting heater of the present invention having the radiation fins 16 heats the lower end of the cooler 10 over a wide range because the thin glass tube 11a is a radiation fin equal to or larger than the upper cover L1. As a result, the defrosting time can be shortened.

  In addition, the outer diameter D3 of the said radiation fin 16 is 29 mm (FIG. 5). In this case, when the depth dimension D2 of the cooler is 60 mm, the heat radiation fin 16 is preferably set to be ½ or less of the depth dimension D2 of the cooler. This is to prevent the defrost heater 11 from becoming resistance to the flow of wind.

  At the same time, even if there is an accident that the glass tube 11a breaks, the heat radiation fin 16 is attached to the outer periphery of the glass tube 11a and the rubber plugs are fixed to each other with the upper cover. Even when 11a is broken, the rubber stopper is supported by the upper cover, and the damaged portion of the glass tube 11a hangs down, so that the glass tube 11a does not tilt, so that the heater wire jumping out of the glass tube 11a hangs down and becomes a peripheral part. There is no damage. Further, when the glass tube 11a is broken, there is no problem of electricity leaking to the metal part of the refrigerator body 1 as in the prior art.

  Next, a second embodiment will be described with reference to FIGS.

  First, in FIG. 5, 17 is a rubber plug, 16 is a radiation fin, and 11a is a glass tube. Since the heat radiating fin 16 is wound so that one end surface in the width direction is orthogonal to the glass tube 11a, naturally, in order to absorb the difference in curvature, a narrowing portion is provided near the inner side (glass tube side) of the radiating fin. 16c is provided and the side opposite the glass tube is made flat.

  The radiating fins 16 are wound around the glass tube 11a between the rubber plugs 17 as shown in the figure. In other words, the radiation fins 16 are provided to the full length of the glass tube 11a between the rubber plugs provided at both ends of the glass tube 11a.

  Reference numeral 16b denotes a bent portion provided at the start and end of the radiating fin. The bent portion 16b is bent toward the side opposite to the end of the glass tube 11a where the rubber plug 17 is located. The bent portion 16b is for preventing the end portion that can be wound around the heat dissipating fin from damaging the rubber plug 17.

  Of course, since the L2 dimension of the bent portion 16b is made smaller than the winding pitch P1, the winding pitch P1 dimension does not change due to the bent portion 16b. The winding pitch P1 is 5 mm to 15 mm.

  Next, in FIG. 6, 11a indicates a glass tube, 11b indicates a heater wire, and 16 indicates a heat radiation fin. As described above, the winding pitch P1 of the radiating fins 16 is 5 to 15 mm.

  The winding pitch P1 and the outer diameter of the heat dissipating fins 16 are pitches that can secure a heat dissipating area necessary to bring the surface temperature of the glass tube 11a to around 300 ° C., and the outer dimensions are 25 to 40 mm (29 mm here). ).

  In addition, the heater wire 11b becomes around 500 ° C. when it generates heat. In order to lower the temperature of the heater wire 11b to 350 ° C., it is necessary to lower the temperature of the glass tube 11a to 300 ° C. It is the role of the radiating fins 16 to do this.

FIG. 6 is a diagram for explaining the winding direction of the heat dissipating fins and the heater wire of the defrosting heater.
In FIG. 6, symbol P2 indicates the winding pitch of the heater wire 11b. Here, although the heater wire 11b has a continuous coil shape, in order to make the explanation easier to understand, a part of the heater wire 11b is omitted from the drawing. For this reason, in this figure, the heater wire 11b is not shown in a continuous state.

  The temperature of the heater wire 11b can also be varied by changing the winding pitch P2 of the heater wire 11b. That is, the smaller the winding pitch P2, the more heater wires 11b occupying the glass tube 11a, and the higher the temperature. Conversely, the larger the winding pitch P2, the fewer heater wires 11b occupying the glass tube 11a. Becomes lower. In the case of the present embodiment, the winding pitch P2 is set so that the temperature of the heater wire 11b is 500 ° C. or lower.

  The winding direction of the radiating fin 16 around the glass tube 11a is opposite to the winding direction of the heater wire 11b wound in a coil shape. This is for preventing the radiation fins 16 and the glass tube 11a from overlapping with each other through the glass tube 11a. That is, when the radiating fin 16 and the heater wire 11b are overlapped, the surface of the glass tube 11a is covered with the inner edge (end surface) of the radiating fin 16 by the radiating fin 16, and the radiating fin from the glass tube 11a. This is because the heat to be radiated to the 16 side is reflected by the inner edge (end surface) of the radiating fin 16 and is returned to the heater wire 11b side to increase the temperature of the heater wire 11b.

  Next, a third embodiment according to the present invention will be described with reference to FIGS.

  In the figure, 10 is a cooler, 11 is a defrost heater, 11a is a glass tube, 11b is a heater wire, 15 is an upper cover, 15a is a fixing part of the upper cover 15, 15b is a fastening part that fastens the fixing parts 15a, 16 is a radiation fin, 17 is a rubber plug, 20 is a soot, 20a is a soot drain, 20b is a soot heating metal plate (aluminum plate), 19 is a lead wire for supplying power to the heater wire 11b, and 20c is a defrosting heater. This is a mounting leg that supports the heel 20.

  In FIG. 8, the upper cover 15 is close to or in contact with the heat radiating fins 16. The upper cover 15 is close to or in contact with the heat radiation fins 16 that have received heat radiation from the glass tube 11a and receives heat from the heat radiation fins 16 so as to defrost the cooler 10.

  Of course, the upper cover 15 also serves to prevent the defrost water dripped from the cooler 10 from directly hitting the glass tube 11a.

  Further, the upper cover 15 is bent at both sides (both ends) of the upper cover 15 toward the glass tube 11a to form an attachment portion 15a, and is attached to the rubber plug 17 using the attachment portion 15a.

  Next, the structure of the attachment portion 15a will be described with reference to FIGS. As shown in FIGS. 7 and 9, the attachment portion 15 a is formed in two parts so as to sandwich the rubber plug 17. One attachment portion 15a is formed with a fastening portion 15b extending from the lower end thereof toward the other attachment portion 15a. As shown in FIGS. 7 and 9B, the fastening portion 15b is provided with an extended portion protruding from the other attachment portion 15a to the side to form a protruding portion 15c.

  Next, the attachment structure of the upper cover 15 and the rubber plug 17 will be described with reference to FIGS. In attaching the upper cover 15 to the rubber plug 17, first, as shown in FIG. 9A, the fastening portion 15b is bent forward or backward to secure an opening 15e into which the rubber plug 17 is inserted. On the other hand, a mounting groove 17 a that is recessed from the surface of the rubber plug 17 is formed on the outer periphery of the rubber plug 17 at the mounting position of the rubber plug 17. A locking portion 17 b is formed below the rubber plug 17 so as to protrude from the surface of the rubber plug 17. Then, as shown in FIG. 9A, the rubber plug 17 is inserted in the direction of the arrow from the opening 15e of the mounting portion 15a so that the mounting groove 17a of the rubber plug 17 and the mounting portion 15a coincide. In this state, as shown in FIG. 9B, the rubber plug 17 and the mounting portion 15a are in contact with the mounting groove 17a of the rubber plug 17 and the flange portion 15d of the mounting portion 15a, and the mounting portion is divided into two parts. It is sandwiched by 15a. At the same time, the locking portion 17b provided below the rubber plug 17 is positioned in the opening 15e, and both sides of the locking portion 17b are sandwiched between the mounting portions 15a. That is, the locking portion 17b has a function as a positioning member, and prevents the rubber plug 17 from rotating in the mounting portion 15a. In this state, the fastening portion 15b bent forward or backward is brought into contact with the other attachment portion 15a. In the case of a present Example, the fastening part 15b bent back is moved ahead, and is located in the back side of the other attachment part 15a. Next, as shown in FIG.9 (c), the front part bends the protrusion part 15c of the fastening part 15b. The other attachment portion 15a is sandwiched between the fastening portions 15b, so that the other attachment portion 15a and the fastening portion are fixed, and as a result, one and the other attachment portions 15a are fixed. In this way, the upper cover 15 is fixed to the rubber plug 17. In the present embodiment, the fixing of the rubber stopper 17 and the upper cover 15 on one end side of the glass tube 11a has been described, but the other end side is the same, although not shown.

  A mounting leg 20c is provided on the synthetic resin ridge 20 so as to protrude upward from below, and a rubber plug 17 is fixed thereto.

  Furthermore, the mounting groove 17a provided in the rubber plug 17 may be formed in a square shape so as to prevent rotation with the mounting portion 15a.

  The upper cover 15 is provided with a stopper 38. The stopper 38 prevents the coil-shaped heat radiation fin 16 from being attached to the glass tube 11a in the lateral direction due to its elasticity, when the heat radiation fin 16 is attached to the glass tube 11a. In particular, when the refrigerator is transported, the refrigerator is tilted or shaken, so that the radiating fins 16 move on the glass tube 11a. In the present embodiment, since the stopper 38 is provided on the upper cover 15, the radiating fins 16 are not displaced even during transportation. The stoppers 38 are preferably attached to both sides of the upper cover 15 in the left-right direction. It is even better if it is attached to the center. Therefore, it is usually effective to devise the upper cover 15 near the rubber plug 17 and provide a stop stopper 38 as shown in the figure. Further, the stopper 38 may be provided at a plurality of locations as a matter of course, a separate stopper may be attached to the upper cover 15. In short, it is good if the radiation fins 16 do not move relative to the glass tube 11a.

  According to the present embodiment, spiral heat radiation fins 16 are provided on the outer periphery of the glass tube 11a, both sides of the upper cover 15 are attached to the rubber plugs 17 provided at both ends of the glass tube 11a, and both ends of the rubber plug 17 are connected. Since the connection is made by the upper cover 15, even when the glass tube 11a is broken, the rubber stopper 17 is held by the upper cover 15, and the glass tube 11a is tilted to prevent the heater wire 11b from dripping onto the flange 20. I can do it.

  Next, a fourth embodiment will be described with reference to FIGS.

  In the figure, 10 is a cooler, 11 is a defrosting heater, 11a is a glass tube, 11b is a heater wire, 16 is a radiation fin, 17 is a rubber stopper, 20 is a gutter, and 20c is a mounting leg.

  First, FIG. 10 assumes that the glass tube 11a is broken due to impact or the like.

  As shown in the figure, the defrost heater 11 is attached to the eaves 20 by suspending rubber plugs 17 provided at both ends of the glass tube 11a on attachment legs 20c provided on the eaves 20 side.

  In other words, since the mounting leg 20c only needs to suspend the defrosting heater, if the glass tube 11a is broken and bent as shown in FIG. 10, the rubber plug 17 is broken by a broken line at the mounting leg 20c. As described above, since the defrosting heater 11 is pulled into the broken position (inner side), the dimension of the defrosting heater 11 in the width direction changes from W3 to W4.

  As a result, the heater wire 11b accommodated in the glass tube 11a jumps out of the broken glass tube 11a and hangs down, contacts the tub 20 made of a synthetic resin, etc., melts the tub 20, and fires in the worst case. There was a possibility of development.

  Moreover, although the radiation fin 16 wound around the outer periphery of the glass tube 11a can prevent the glass tube 11a from being bent to some extent, if the glass tube 11a is broken at several places at the same time, the glass tube 11a is bent. As a result, the spacing (pitch) between the heat dissipating fins changes partially, making it difficult to hold the glass tube 11a at the dimension W3 in FIG.

  This is nothing but the mounting leg 20c used as a means for suspending the defrosting heater 11. Therefore, in this embodiment, as shown in FIG. 11, the rubber plug 17 is not horizontally suspended but has a function of holding the rubber plug 17 horizontally.

  That is, as shown in the figure, the mounting leg 20c shown in this embodiment holds the rubber plug 17 using the elasticity of the mounting leg itself, and also holds the rubber plug 17 of the defrosting heater 11 horizontally. It is equipped with.

  By configuring as described above, even if the glass tube 11a is broken and the glass tube 11a is bent, the rubber plug 17 is held horizontally by the holding portion 20d, so that the glass tube 11a is bent to some extent. It can be prevented.

  As a result, the bending of the glass tube 11a expands, and the accident that the heater wire 11b hangs downward from the cracked portion is eliminated.

  Next, a fifth embodiment will be described with reference to FIGS.

  11 is a defrost heater, 11a is a glass tube, 11b is a heater wire, 15 is an upper cover, 15f is an insertion portion, 16 is a heat radiating fin, 17 is a rubber plug, 17a is a fitting groove, 18 is a positioning member, and 19 is a lead. Line 21 is a connection fitting.

  First, the mounting structure of the upper cover 15 shown in FIGS. 12 and 13 is different from FIGS. 7 to 9 in that an insertion portion 15f is formed at the end of the upper cover 15, and this insertion portion 15f is provided on the rubber plug 17 side. The upper cover 15 and the rubber plug 17 are fixedly inserted into the fitting groove 17c. The rubber plugs 17 arranged on both sides of the glass tube 11a are connected and fixed by the upper cover 15.

  Of course, as described with reference to FIGS. 7 to 9, the upper cover 15 is provided so as to be close to or in contact with the radiating fins 16, and serves as a radiating material when the defrost heater 11 generates heat.

  As described above, since the upper cover 15 has a shape in which the rubber plugs are firmly connected to each other, even if the glass tube 11a is broken by an impact or the like, the width of the glass tube 11a changes from W3 to W4. There is nothing.

  Next, a method for more reliably preventing the glass tube 11a from being bent will be described with reference to FIGS. In the present embodiment, a wire-like support member 37 is installed below the radiating fin 16. When the glass tube is broken (including when the complicated portion is cracked) and the glass tube is about to be bent together with the heat radiation fin, the wire-like support member 37 is prepared together with the upper cover 15 together with a pilot hole (see FIG. Two wire-like support members press-fitted into the glass tube 11a are supported from below to prevent the glass tube 11a from being bent.

  By comprising in this way, the complication of the attachment leg 20c shown in FIG. 11 can further be prevented.

  At this time, the two wire-like support members 37 act to reflect the heat rays emitted from the glass tube 11a and return it to the glass tube 11a side again. Therefore, it is preferable that the two wire-like support members 37 have rigidity as much as possible and have a small surface area. Further, the support member 37 may be a wire netting or a punched product of a plate material as long as it has a small surface area.

  Further, like the upper cover 15, the support member 37 is also brought into contact with the heat radiation fins 16 so as to become a heat radiation material when the defrost heater 11 generates heat.

  The radiating fins 16 made of the strip-like thin plate described in the first to fourth embodiments are wound at a pitch of 5 mm to 15 mm and so that the width direction is orthogonal to the glass tube 11a as shown in the figure. Therefore, the rate at which the heat rays coming out of the glass tube 11a hit the heat radiation fins 16 and return to the glass tube 11a to raise the temperature of the heater tube 11b as well as the glass tube 11a is very small.

  Further, the heat ray returned to the upper cover 15 is the same as the conventional one.

  Next, an example in which a defrost heater is used in a refrigerator using hydrocarbon-based isobutane as a refrigerant will be described with reference to FIGS. 16 and 17.

FIG. 17 shows a refrigeration cycle, in which a compressor 26, a condenser 27, a capillary tube 28, and a cooler 29 are connected in series and annularly to constitute a refrigeration cycle. Further, 30 is a cold air circulation fan, and 31 is a defrost heater. Usually, the refrigerant enclosed in the refrigeration cycle uses a fluorocarbon refrigerant because of its stable physical properties and easy handling.
However, in recent years, the adoption of hydrocarbon refrigerants such as propane (R-290a) and isobutane (R600a) that have extremely little effect on the destruction of the ozone layer and global warming has been attempted.
Hereinafter, this hydrocarbon refrigerant is referred to as HC refrigerant.

  This HC refrigerant is sealed in the refrigeration cycle of the present embodiment. The HC refrigerant leaks into the refrigerator during the defrosting operation when the welded part of the cooler 29 is damaged.

  When this HC refrigerant fills the refrigerator, there is a risk of igniting the HC refrigerant when the defrost heater generates heat.

That is, since the cooler is heated by the defrost heater during the defrosting operation, the isobutane in the cooler 29 becomes a pressure higher than the atmospheric pressure (about 3 kg / cm ² ) and leaks into the refrigerator. During the cooling operation, isobutane in the cooler has a negative pressure relative to the atmospheric pressure, so that isobutane does not leak into the refrigerator.
Furthermore, even if the compressor is stopped, the isobutane in the cooler is almost the same as the atmospheric pressure, so that it hardly leaks into the refrigerator.

  The cold air circulation fan 30 forcibly circulates the cold air cooled by the cooler 29 to the freezer compartment or the refrigerator compartment. Further, the defrosting heater 31 is for melting the frost when the frost is accumulated in the cooler 29, and its specific configuration is as shown in FIG.

  In the figure, 31 is a defrost heater, 31a shows a glass tube, and 31b shows a heater wire. The heater wire 31b includes a coil part a and a coil end part b. The coil part a is wound around a coil having an outer diameter of 7.5 mm when the inner diameter of the glass tube 31a is 8.5 mm. And this winding pitch is wound at 2.0 mm or less. When the winding pitch is 2.0 mm or less, the temperature rises more than the heat generation of the coil portion a itself of the heater wire 31b due to the influence of adjacent heater wires.

  In the defrost heater 31 having the above-described configuration, the temperature of the glass tube 31a facing the coil portion a rises to near the heater wire 31b temperature as described in the previous embodiment. In the present embodiment, the coil portion a is wound to an outer diameter of 7.5 mm, and the inner diameter of the glass tube 31a is 8.5 mm. Therefore, the temperature of the portion of the glass tube 31a facing the coil portion a is a heater. Since the temperature is close to the temperature of the wire 31b, the rubber plugs 32 at both ends are damaged by the heat.

  The straight line portion b of the heater wire 31b indicates a portion where the heater wire 31b is straightened to prevent damage to the rubber plugs 32 at both ends. Since the amount of heat generated in this portion is naturally small, the temperature of the portion of the glass tube 31a facing the straight portion b does not reach the temperature of the glass tube 31a corresponding to the coil portion a.

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

The rubber plug 32 seals both ends of the glass tube 31a and is made of heat-resistant (for example, 145 ° C.) silicon rubber or the like.
A partition plate 33 is provided at the end of the glass tube and positions the coil portion a of the heater wire 31b. Reference numeral 34 denotes a connection fitting for connecting the coil end portion b and the lead wire 35. The position of the connection fitting 34 is also determined by the previous partition plate 33. Thereby, the L2 dimension of the rubber plug 32 and the coil part a can be set to a predetermined dimension.

  In the refrigerator including the defrost heater 31 having such a configuration, frost accumulates in the cooler 29 and energization to the defrost heater 31 is started when defrosting is necessary. When energization of the defrost heater is started, if there is a damaged part in the cooler 29, the HC refrigerant leaks from the damaged part. Since the ignition temperature of this HC refrigerant, for example, isobutane is 494 ° C., it is necessary to make the temperature of the heater wire 31b lower than the ignition temperature. In the present embodiment, for example, 394 ° C. is set in consideration of safety.

  In other words, in the present embodiment, the radiating fins 36 are provided on the defrosting heater 31 (glass tube 31a, heater wire 31b), and the temperature is 394 ° C. or lower. The radiating fin 36 may be arbitrarily selected in the shape and form shown in the first, second, third, etc. What is needed is a heat radiating member (heat radiating fin) capable of lowering the temperature of the defrosting heater 31, for example, a heat radiating member having a higher thermal conductivity than the glass tube 31a.

  In the present embodiment, a single glass tube is used instead of a double glass tube heater which is used in consideration of explosion resistance against the flammable refrigerant. In the single glass tube as described above, the temperature of the glass tube 31a can be lowered by the radiating fin 36, and the air temperature in the glass tube 31a can also be lowered by this action. Therefore, the heater wire provided in the glass tube The temperature rise of 31b can be suppressed, and the temperature of the heater wire 31b can be reduced to 394 ° C. or lower.

  That is, when a double glass tube is used, the air between the inner glass tube and the outer glass tube serves as a heat insulating material, and even if a heat radiating fin is attached, the heater wire temperature is 394 ° C. or lower. In other words, a method such as changing the winding pitch is required. In this embodiment, the structure is different from the double glass tube in which the heat insulating air layer is generated and the heat efficiency remains, and the heat of the heater wire 31b is taken away by the radiating fin through the glass tube. The temperature of the wire can be 394 ° C. or lower. Moreover, since the heat of the heater wire 31b is efficiently transmitted to the surroundings by the heat radiating fins 36 as described above, the defrosting of the cooler 29 can be performed with low power consumption.

Since the present invention has the configuration as described above, it has the following effects.
That is, in a refrigerator in which a heater wire wound in a coil shape in a glass tube and a defrosting heater sealed at both ends with rubber plugs is installed on a mounting leg provided on the heel side, the inner circumference is the above glass Since the heat dissipating members (heat dissipating fins) attached so as to be in contact with or close to the outer periphery of the tube are provided between the rubber plugs, the heat rays coming out of the heater wire do not return to the defrosting heater again. In addition, since a metallic upper cover is provided so as to be in contact with the heat radiating member and both ends of the upper cover are fixed to the rubber plug, the rubber plug and the upper cover are fixed even when the glass tube is broken, Since the glass tube is supported by the rubber stopper and does not tilt, the heater wire can be prevented from hanging down.
At the same time, in the present invention, the temperature of the heater wire as well as the temperature of the glass tube can be lowered. By this, the refrigerator which can eliminate the damage of a rubber stopper, etc. is obtained.
In addition, the glass tube between the rubber plugs is prevented from being bent by the rigidity of the upper cover made of aluminum or the like, and the upper cover is brought into contact with the heat dissipation member, so that it is possible to prevent the glass tube from being bent. Of course, the upper cover helps the heat dissipation of the heat dissipation member.
In addition, since a supporting member for preventing the glass tube from being bent is provided at the lower part of the heat radiating member (heat radiating fin), the defrosting heater that breaks and bends the glass tube is provided with the upper cover and this. The glass tube is reinforced with a support member and maintains a straight state.
Further, the support member is fixed to the rubber stopper and has a wire shape, and prevents the heat radiation fin from collapsing when the glass tube is broken. Moreover, since this support member is a wire-like member, the heat rays hitting the wire-like support member are returned to the inside of the glass tube, and the temperature inside the glass tube and the heater wire temperature are not increased abnormally.
Also, a strip-like thin plate forming a heat radiating member is wound around a glass tube in a coil shape to constitute a heat radiating fin, and the winding direction of the heat radiating fin around the glass tube is reversed to the winding direction of the heater wire wound in the coil shape Therefore, the heater wire and the heat radiating fin overlap, and the heat radiating of the heater wire is not hindered by the heat radiating fin.
In addition, since the mounting leg that fits and supports the rubber plug of the defrost heater has a holding portion in which the rubber plug is not inclined even when the glass tube is broken, the glass is accompanied by the rigid support of the upper cover. When the tube is bent, the glass tube is not inclined and the heater wire does not hang down.
In each of the embodiments according to the present invention described above, a refrigerator having a structure in which a refrigerator compartment is arranged in the lower part of the freezer compartment has been described. However, the arrangement of each compartment is not limited to this. For example, it may be a refrigerator room, a vegetable room, and a freezer room in order from the top, or may be arranged like a refrigerator room, a freezer room, and a vegetable room. What is necessary is just to change the arrangement | positioning of each chamber as needed. If it is the structure provided with the heater for defrosting under the cooler, it can be employ | adopted also in such a refrigerator.

It is a longitudinal cross-sectional view of the refrigerator provided with this invention. It is a principal part enlarged view of FIG. It is a cross-sectional explanatory drawing of the defrost heater of FIG. It is a heat sink fin perspective view in FIG. It is a principal part expansion perspective view of the defrost heater explaining the implementation shape different from FIG. It is a figure explaining the winding direction of the radiation fin and heater wire of a defrost heater provided with the present invention. It is a figure which shows the relationship with a soot in the figure which looked at the defrost heater in FIG. 5 from the arrow P direction. It is an AA cross-section equivalent view of FIG. It is a figure which shows the attachment method of an upper cover and a rubber stopper. It is a figure explaining a motion of a defrost heater when a glass tube of a defrost heater is broken in order to explain the present invention. This is an improved product of the mounting leg 20c in FIG. It is a figure which shows the fastening relationship of a rubber stopper and an upper cover. It is BB sectional explanatory drawing of FIG. It is a figure which shows the Example different from FIG. It is CC sectional explanatory drawing of FIG. It is a figure explaining the winding pitch etc. of a defrost heater. It is explanatory drawing of the refrigerating cycle provided with this invention. It is a longitudinal cross-sectional view of a conventional refrigerator. It is a cross-sectional explanatory drawing of the defrost heater part of FIG. It is a principal part expansion explanatory drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Refrigerator main body, 2 ... Freezer room, 3 ... Cold room, 4 ... Freezer room door, 5 ... Cold room door, 6 ... Middle partition wall, 7 ... Passage, 8 ... Passage, 9 ... Cooler room, 10 ... Cooling 11: Defrost heater, 11a ... Glass tube, 11b ... Heater wire, 11c ... Coil end part, 12 ... Cold air circulation fan, 13 ... Partition partition, 14 ... Cold air outlet, 15 ... Top cover, 15a ... Mounting leg 15b ... Clamping piece 15c ... Insertion side 16 ... Heat radiating member (heat radiating fin), 16a ... Center hole, 17 ... Rubber plug, 17a ... Mounting groove, 18 ... Positioning member, 19 ... Lead wire, 20 ... Hot, 20a ... Drain port 20b ... metal plate for heating, 20c ... mounting leg, 20d ... support part, 21 ... connection fitting, 26 ... compressor, 27 ... condenser, 28 ... capillary tube, 29 ... cooler, 30 ... cool air circulation fan, 31 ... Defrost heater, 31a ... Glass tube, 3 b: Heater wire, a ... Coil part b ... Coil end part, 32 ... Rubber plug, 33 ... Partition plate, 34 ... Connection fitting, 35 ... Lead wire, 36 ... Radiation fin, 37 ... Support member, 38 ... Stopper, 51 DESCRIPTION OF SYMBOLS Refrigerator main body 52 ... Freezing room, 53 ... Refrigeration room, 54 ... Freezing room door, 55 ... Refrigeration room door, 56 ... Partition wall, 57 ... Passage, 58 ... Passage, 59 ... Cooler room, 60 ... Cooler 61 ... Defrost heater, 61a ... Glass tube, 61b ... Heater wire, 61c ... Coil end part, 62 ... Cold air circulation fan, 63 ... Partition partition, 64 ... Cold air outlet, 65 ... Upper cover, 66 ... Protection plate, 67 ..., 68, lead wire, 69 ... connection fitting, 70 ... rubber plug, 71 ... lead wire through hole.

Claims (6)

A cooler, a defrost heater provided below the cooler for defrosting the frost attached to the cooler, a heat dissipating member provided on the outer periphery of the defrost heater, and provided below the defrost heater A bowl that receives defrost water falling from the cooler, and an upper cover that is provided above the defrost heater and protects the defrost heater from defrost water falling from the cooler,
The defrosting heater has a glass tube, a heater wire built in the glass tube, and a rubber plug for sealing both ends of the glass tube,
The refrigerator is characterized in that both ends of the upper cover are fixed to the rubber plugs. In claim 1,
The refrigerator is characterized in that the upper cover is made of metal. In claim 1 or 2,
The said heat radiating member is formed in the helical form, The refrigerator characterized by the above-mentioned. In claim 3,
A refrigerator comprising a supporting member for preventing the glass tube from being bent below the heat radiating member. In claim 4,
The refrigerator, wherein the support member is composed of a wire fixed to a rubber stopper. In any one of Claims 3-5,
The refrigerator is characterized in that the heater wire is wound in a coil shape, and the winding direction of the heat radiating member around the glass tube is different from the winding direction of the heater wire.

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