JP3554562B2 - Defrost heater and refrigerator equipped with defrost heater - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a refrigerator having a refrigerant circuit using a flammable refrigerant, to a defrosting heater for melts the frost in particular adhered to the cooler.
[0002]
[Prior art]
In recent years, refrigerators using a flammable refrigerant such as isobutane having a low global warming coefficient instead of the R134a refrigerant having a high global warming coefficient have become widespread from the viewpoint of preventing global warming. In the refrigerator using flammable refrigerant it has been requested that improve safety with respect to the heater for defrosting.
[0003]
Hereinafter, a conventional defrost heater will be described with reference to the drawings.
[0004]
FIG. 4 is a cross-sectional view illustrating a structure of a conventional defrosting heater used in a refrigerator using a combustible refrigerant, and FIG. 5 is a plan view illustrating a state in which the defrosting heater is used.
[0005]
In the defrosting heater 50 in FIG. 4, a heater wire 41 wound in a coil shape is housed in a first glass tube 42. The first glass tube 42 is housed in a second glass tube 43, and the second glass tube 43 is further surrounded by a third glass tube 44.
[0006]
Both ends of the first glass tube 42, the second glass tube 43, and the third glass tube 44 are sealed with caps 45 and 46 made of a material having good heat resistance and insulation such as silicon rubber. Is connected to a cord 47 passing through the caps 45 and 46.
[0007]
The operation of the defrost heater configured as described above will be described below.
[0008]
As shown in FIG. 5, when the frost adheres to the evaporator 51 built in the refrigerator or the like and the cooling capacity decreases, the heater 50 for defrost disposed below the evaporator 51 is energized to start defrosting. I do. The air heated by the defrost heater 50 rises upward and warms the evaporator 51 to melt the frost. Further, the defrosting heater 50 composed of a transparent glass tube defrosting warm directly evaporator by radiant heat.
[0009]
If the flammable refrigerant used in the cooling circuit leaks to the periphery of the evaporator 51 for some reason, the periphery of the defrosting heater 50 is also filled. At this time, the heat of the heater at the time of defrosting is ignited. For example, in the case of isobutane, the surface temperature of the defrosting heater 50 is specified by JEMA standards so as to be 394 ° C. or lower, which is sufficiently lower than the ignition point of 494 ° C. so as not to become a source.
[0010]
Although the surface temperature of the heater wire 41 at the time of defrosting is about 700 ° C., the first glass tube 42, the second glass tube 43, and the third glass tube 44 surround the periphery, so that the outermost third glass tube 42 is formed. the surface temperature of the glass tube 44 to 394 ° C. or less, and to be able to safely defrosting (e.g., see Patent Document 1.).
[0011]
[Patent Document 1]
Japanese Patent Application Laid-Open No. H11-257831
[Problems to be solved by the invention]
However, construction of the conventional defrosting heater, had the disadvantage of very poor assembling workability because that is the three independent multiple structure of the glass tube.
[0013]
In the case of the heater for defrosting shown in FIG. 4, the heater wire 41 is housed in the first glass tube 42 and attached to the cap 45 first. The subsequent second glass tube 43, further attaching a third glass tube 44 to the cap 45 is assembled and finally attach the opposite side of the cap 46.
[0014]
However, during the work of attaching the second glass tube 43 and the third glass tube 44, it is likely that the glass tube comes into contact with another glass tube and is damaged. In addition, the cap 46 must be attached at the same time as three glass tubes, and each of the glass tubes is attached to the cap 45 on one side in an unstable state such as elastic force of rubber, so that positioning is performed. It is difficult and very difficult work.
[0015]
The present invention is intended to solve the above problems, it is used in a refrigerator using a flammable, and an object thereof is to provide a defrosting heater with excellent assembly workability.
[0016]
[Means for Solving the Problems]
The invention of a heater for defrost according to claim 1 of the present invention is a defrost heater for melting frost adhering to a cooler of a refrigerant circuit filled with a flammable refrigerant, wherein linear heaters are provided at both ends of a coil-shaped heater region. A heater wire having a heater region formed therein and a glass tube for housing the heater wire, wherein the glass tube is a monolithic structure integrally formed of a small-diameter glass tube and a large-diameter glass tube; While the wire is housed in the internal space of the small-diameter glass tube, the coil-shaped heater area is arranged in the area of the double structure, and a defrost heater that has taken a measure to reduce the surface temperature when using a flammable refrigerant is provided. realization can, and thus improving the assembling workability by integral double pipe while reducing the size of the cap of the glass tube ends.
[0017]
Next, the invention of claim 2 is the invention according to claim 1, which is provided a hole in the glass tube to be the inside of the glass tube of the multiple structure, and the inner glass tube and the outer glass tube Even if the gas in the space surrounded by is expanded or contracted, the gas flows through the inner glass tube through the hole, so that the glass tube is not ruptured or damaged by the expansion or contraction of the gas.
[0018]
Next, the invention of claim 3 is the invention according to claim 1 or claim 2, comprising a cap for sealing the glass tube, the outer diameter of the cap than the maximum outer diameter of the glass tube but also has increased, it has an effect to prevent damaging the glass tube during material handling defrosting heater assembly.
[0019]
Next, an invention of a refrigerator according to a fourth aspect is provided with the heater for defrost according to any one of the first to third aspects below a cooler. when the flammable refrigerant becomes sufficiently low surface temperature was leaking also can perform defrosting safely cooler.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a defrost heater according to the present invention will be described with reference to the drawings. In addition, about the same structure as a conventional one, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.
[0021]
(Embodiment 1)
FIG. 1 is a cross-sectional view of the defrost heater according to Embodiment 1 of the present invention.
[0022]
One end of the heater wire 41 is a linear heater area 41a formed in a linear shape, and the other area is a coil-shaped heater area 41b wound in a coil shape. The lead wire 47 is connected and power is supplied.
[0023]
Glass tube 1 is thicker outer diameter of the central portion, and tapered at both ends portion, which is continuously increased from the minimum diameter of the end portion to the maximum diameter of the central portion. This eliminates the extreme constriction in the glass tube, it is also not easily broken safety when an external force is applied during assembly.
[0024]
When the heater wire is housed in the glass tube 1, the linear heater region 41 a of the heater wire 41 is arranged in the region of the minimum diameter of the glass tube 1, and the coil-shaped heater region 41 b of the heater wire 41 is placed in the glass tube 1. It is arranged in an area other than the area of the minimum diameter.
[0025]
The support member 3 is made of a material having good insulation such as mica, and is inserted into the heater wire 41. The support member 3 prevents the heater wire 41 from bending and approaching the central surface of the glass tube 1 having a large outer diameter to prevent the surface temperature from being partially increased. Both ends of the glass tube 1 is closed by a cap 4 made of a material excellent in heat resistance and electrical insulation properties such as silicone rubber.
[0026]
The heater wire 41 reaches approximately 700 ° C. at the center and approximately 500 ° C. at both ends due to energization during defrosting. But the surface temperature of the glass tube 1 so that it becomes about 300 ° C. at both ends in the central portion, a diameter of about 20mm in the central portion is set to a diameter of about 11mm at both ends.
[0027]
Although the outer diameter of both ends of the glass tube 1 is smaller than that of the central portion, since the linear region of the heater wire 41 is arranged, the calorific value is small and the temperature rise at both ends is suppressed.
[0028]
Therefore, for example, when the flammable refrigerant is isobutane, the surface temperature becomes sufficiently lower than the ignition point of 494 ° C., and even if the flammable refrigerant leaks, defrosting can be performed safely.
[0029]
Defrosting heater of the present structure can be surface temperature depending on the type of the flammable refrigerant used is prepared by varying the diameter of the glass tube so as to be below its ignition point.
[0030]
This heater for defrosting is assembled by inserting the heater wire 41 into which the support member 3 is inserted into the glass tube 1 and attaching caps 4 at both ends. Since a plurality of glass tubes are not used in multiples, damage to the glass tubes during assembly is extremely reduced. Also, the cap 4 can be easily attached.
[0031]
Note that the support member 3 may be supported from the outside without entering the inside of the coil-shaped heater wire 41.
[0032]
The outer diameter D of the cap 4 is larger than the maximum outer diameter d of the glass tube 1 so as not to damage the glass tube 1 during material handling during a distribution process or handling. If you put, as the glass tube 1 is not exposed directly to the table, it is less likely to be scratched into the glass tube 1.
[0033]
In addition, the outer diameter D of the cap 4 and the maximum outer diameter d of the glass tube are not limited to a circle, and the glass tube 1 is placed in such a manner that the glass tube 1 does not come into contact with the desk when the defrost heater is placed on the desk. It is sufficient that the outer periphery of the cap 4 is large over the entire outer periphery of.
[0034]
Depending on the conditions, the cap 4 itself can be reduced in size if there is no fear of damage to the glass tube 1 during handling, and the cost of the defrost heater can be reduced by taking measures to reduce the surface temperature when using a flammable refrigerant.
[0035]
Further, even when the outer diameter of the cap 4 is made larger than the maximum outer diameter d of the glass tube 1, the intended purpose can be achieved even if the outer diameter of the cap 4 is increased not in the entire outer periphery but in a part thereof. Cost can be reduced.
[0036]
As described above, in the defrosting heater according to the present embodiment, since the diameter of the center of the glass tube 1 that accommodates the heater wire 41 is larger than the diameter of both ends, the glass tube 1 having a low surface temperature excellent in assembling workability is provided. A heater for frost can be secured.
[0037]
Further, by having the insulating support member 3 for supporting the heater wire 41, the heater wire 41 can be positioned at the center of the glass tube 1, and a defrosting heater having a low surface temperature and excellent assembling workability can be provided. Can be secured.
[0038]
Further, since the outer diameter of the cap 4 for sealing the glass tube 1 is larger than the maximum outer diameter of the glass tube 1, it is possible to secure a defrost heater excellent in assembling workability without damaging the glass tube during material handling. it can.
[0039]
(Embodiment 2)
FIG. 2 is a cross-sectional view of a defrost heater according to Embodiment 2 of the present invention.
[0040]
Glass tube 11 in Figure 2 has a double structure at the central portion, the large diameter glass tube outer is configured so as to be integrated in the central portion of the inner small diameter glass tube 13 as a supporting member of the heater wire 41 ing.
[0041]
The inner small-diameter glass tube 13 is provided with a hole 15. Even if the gas in the outer large-diameter glass tube expands due to the heat generated by the heater wire 41, the gas flows through the hole 15 to adjust the pressure. , Preventing the glass tube from bursting.
[0042]
Thus, to support the outer heater wire 41 in the glass tube itself, the assembling workability becomes better defrosting heater if by increasing constitutes an outer diameter only a central portion.
[0043]
As described above, in the defrost heater of the present embodiment, since a part of the glass tube 11 is an integral member having a multi-layer structure, it is possible to secure a defrost heater with excellent surface mountability and low surface temperature. it can.
[0044]
In addition, since the support member is glass integrally formed with the glass tube 11, a heater for defrosting with excellent assembling workability can be secured.
[0045]
(Embodiment 3)
FIG. 3 is a sectional view of a defrost heater according to Embodiment 3 of the present invention.
[0046]
In FIG. 3, the glass tube 21 is integrally formed so as to have a double structure over the entirety. In this case, the glass tube can be easily manufactured and is effective.
[0047]
As described above, in the defrost heater of the present embodiment, since all of the glass tubes 21 are of a multi-layered structure, a defrost heater having a low surface temperature and excellent assembling workability can be secured. .
[0048]
【The invention's effect】
Above-described invention defrost heater according to claim 1 as, in the defrosting heater to melt frost adhering to the cooler of the refrigerant circuit filled with a flammable refrigerant in the interior, both ends of the coil-shaped heater region A heater wire having a linear heater region formed therein and a glass tube for housing the heater wire, wherein the glass tube is a monolithic structure integrally formed of a small-diameter glass tube and a large-diameter glass tube. Since the heater wire is housed in the internal space of the small-diameter glass tube and the coil-shaped heater region is arranged in the double-structured region, the defrosting heater having a low surface temperature and excellent assembling workability is provided. Can be realized.

[0049]
According to a second aspect of the present invention, in the first aspect of the present invention, a hole is provided in the glass tube inside the glass tube having the multiplex structure, and is surrounded by the inner glass tube and the outer glass tube. Even if the gas in the enclosed space expands or contracts, the gas flows through the inner glass tube through the hole, so that the glass tube does not burst or be damaged by the expansion or contraction of the gas.
[0050]
The invention according to claim 3 is the invention according to claim 1 or 2, further comprising a cap for sealing the glass tube, wherein an outer diameter of the cap is larger than a maximum outer diameter of the glass tube. Therefore, it is possible to prevent the glass tube from being damaged at the time of material handling, and the assembling workability is improved.
[0051]
According to a fourth aspect of the present invention, there is provided a refrigerator provided with the defrosting heater according to any one of the first to third aspects below a cooler, wherein a flammable refrigerant is leaking. In this case, the cooler can be safely defrosted.
[Brief description of the drawings]
FIG. 1 is a sectional view of a first embodiment of a defrost heater according to the present invention. FIG. 2 is a sectional view of a second embodiment of a defrost heater according to the present invention. FIG. 3 is a sectional view of a defrost heater according to the present invention. FIG. 4 is a cross-sectional view of a conventional defrost heater. FIG. 5 is a plan view showing an arrangement state of a conventional defrost heater.
1, 11, 21 Glass tubes 3, 13 Support member 4 Cap 15 Hole 41 Heater wire 41a Linear heater area 41b Coiled heater area

Claims (4)

What is claimed is: 1. A defrosting heater for melting frost adhering to a cooler of a refrigerant circuit filled with a flammable refrigerant, wherein a heater wire having a linear heater region formed at both ends of a coil-shaped heater region and a glass for housing the heater wire. has a tube, together with a part of the glass tube is an integral of the more becomes double structure and the small diameter glass tube and the large diameter glass tube, housing the heater wire in the internal space of the small diameter glass tube, the coil A heater for defrosting , wherein a heater-like region is arranged in the region of the double structure . The heater for defrosting according to claim 1, wherein a hole is provided in the glass tube inside the glass tube having the multiple structure. The defrost heater according to claim 1 or 2, further comprising a cap for sealing the glass tube, wherein an outer diameter of the cap is larger than a maximum outer diameter of the glass tube. A refrigerator provided with a defrost heater according to any one of claims 1 to 3 below a cooler.

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