JP2006258303A - Defrosting heater for domestic refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce possibility of firing of inflammable refrigerant by reducing a surface temperature of a glass pipe. <P>SOLUTION: The defrosting heater for a domestic refrigerator comprises an inner glass pipe; a heater wire inserted into the inner glass pipe; an inner sealing cap for sealing an end opening of the inner glass pipe; an outer glass pipe inserted with the inner glass pipe and surrounding an outer periphery of a coil part of the heater wire; and an outer sealing plug for sealing an end opening of the outer glass pipe. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a defrost heater for a household refrigerator.

  In response to environmental regulations to prevent global warming, non-fluorocarbon refrigerators using isobutane, which are flammable instead of fluorocarbons, are rapidly spreading in household refrigerators.

  Hereinafter, a conventional defrost heater for a household refrigerator will be described with reference to the drawings.

  FIG. 7 is a longitudinal sectional view of a main part of a conventional household refrigerator. In FIG. 7, 101 is a refrigerator body, 102 is a refrigeration room inside the refrigerator body 101, 103 is a freezer room inside the refrigerator body 101, 104 is a refrigerator room door, 105 is a freezer room door, and 106 is a refrigerator room 102. And a partition wall for partitioning the freezer compartment 103, 107 a refrigerator compartment inlet for sucking air in the refrigerator compartment 102, 108 a refrigerator compartment inlet for sucking air in the refrigerator compartment 103, 109 a discharge outlet for discharging cool air, 110 An evaporator, 111 is a fan that circulates cold air, 112 is an evaporator partition wall that partitions the evaporator 110 and the refrigerator compartment 102, 113 is a bowl, 114 is a drain, 115 is a coiled nichrome wire made of glass tube The defrosting heater covered 116 is a heater cover for preventing the defrosting water from directly dropping and contacting the defrosting heater 115, and 117 is a cooling chamber for accommodating the cooler 110. That.

  Next, the operation will be described.

  When cooling the refrigerator compartment 102 or the freezer compartment 103, the refrigerant flows through the evaporator 110 and the evaporator 110 is cooled. In the same manner, by operating the fan 111, the heated air in the refrigerator compartment 102 and the freezer compartment 103 is sent from the refrigerator compartment suction port 107 and the freezer compartment inlet port 108 to the cooling chamber 117, and is cooled by heat exchange in the evaporator 110. Then, the cooling air is sent into the refrigerator compartment 102 from the discharge port 109, and the cool air is sent from the refrigerator compartment 102 to the freezer compartment 103 through a communication port (not shown).

  Here, the air that exchanges heat with the evaporator 110 is humidified by the inflow of high-temperature outside air by opening and closing of the refrigerator compartment door 104 and the freezer compartment door 105, evaporation of moisture in the stored food in the refrigerator compartment 102 and the freezer compartment 103, and the like. Therefore, moisture in the air forms frost and forms frost on the evaporator 110 having a temperature lower than that of the air.

  As the amount of frost increases, the heat transfer between the surface of the evaporator 110 and the air that exchanges heat is hindered, and the air flow decreases and the amount of air decreases, resulting in a decrease in heat passage rate and insufficient cooling. .

Therefore, the nichrome wire of the defrost heater 115 is energized before the cooling becomes insufficient. When energization of the nichrome wire is started, heat rays are radiated from the nichrome wire to the evaporator 110 and peripheral components. At this time, a part of the radiated heat ray is reflected by the heater cover 116 and the other part is reflected toward the evaporator 110 and other peripheral parts. As a result, the frost that has arrived in the vicinity of the evaporator 110, the trough 113, and the drain outlet 114 is melted into water. Further, a part of the defrost water melted in this way falls directly on the ridge 113, and the other falls on the ridge 113 avoiding the defrost heater 115 by the heater cover 116, and is drained from the discharge port 114 to the outside.
JP 2004-044899 A JP 2002-195735 A

  In adopting isobutane, which is a flammable refrigerant, the safety of a defrost heater having a high-temperature heat source is an important issue for refrigerator electrical parts.

  Therefore, the Japan Electrical Manufacturers' Association has an ignition temperature of isobutane of 494 ° C. Therefore, in the defrost heater that melts the frost attached to the cooler, the surface temperature is voluntarily set to less than 394 ° C, which is 100 ° C lower than this. Standards have been established to prevent the risk of fire and explosion if a refrigerant leaks.

  On the other hand, since the surface temperature of the conventional glass tube heater for chlorofluorocarbon is 564 ° C, which is much higher than the standard value, the current product is a standard with a method of increasing the radiation area by making it a double glass tube structure covered with a glass tube. It is used as a defrost heater for non-fluorocarbon refrigerators.

  However, the glass double structure in which the entire surface is covered with a glass tube has a problem that the surface temperature of the glass tube does not decrease sufficiently efficiently.

  The double glass tube defrost heater attempts to increase the radiation area of heat generated from the heater wire to lower the surface temperature of the outer glass tube, but it is not sufficient.

  In the present invention, the coil portion of the effective heating length of the heater wire accommodated in the inner glass tube is covered with the outer glass tube, so-called cold straight end lines at both ends of the heater wire are not covered, and both end portions of the inner glass tube are covered. Further, the surface temperature of the outer glass tube is lowered by promoting heat dissipation.

  The present invention provides an inner glass tube, a heater wire inserted through the inner glass tube, an inner sealing cap for sealing the inner glass tube end opening, and the inner glass tube, in order to reduce the surface temperature of the outer glass tube. A defrosting heater for a household refrigerator comprising an outer glass tube that loosely inserts a glass tube and surrounds the outer periphery of the coil portion of the heater wire and an outer sealing plug that seals the outer glass tube end opening.

  In addition, the present invention provides an outer sealing plug that seals the opening of the outer glass tube at the time of heating so as to have a flame extinguishing distance that prevents a fire from propagating to the outside even if an ignition explosion occurs in the outer glass tube. The opening part which discharge | releases the thermal expansion air of was provided.

  Furthermore, in the present invention, heat radiation fins are provided on the surface of the inner glass tube not surrounded by the outer glass tube in order to promote heat dissipation at the end portion of the inner glass tube and lower the temperature of the inner glass tube center.

  Furthermore, in the present invention, the length of the outer glass tube is set to be shorter than the length of the inner glass tube by 40 mm or more in order to specify a region where the heat dissipation effect is remarkable.

  Furthermore, the present invention sets the surface temperature of the inner glass tube to less than 394 ° C. so that there is no danger of ignition or explosion even if a flammable refrigerant enters the outer glass tube.

  The present invention provides an inner glass tube, a heater wire inserted through the inner glass tube, an inner sealing cap for sealing the inner glass tube end opening, and the inner glass tube, in order to reduce the surface temperature of the outer glass tube. A defrosting heater for a domestic refrigerator, comprising an outer glass tube that loosely inserts a glass tube and encloses the outer periphery of the coil portion of the heater wire, and an outer sealing plug that seals the end opening of the outer glass tube. Therefore, the length of the outer glass tube can be shortened compared with the conventional defrosting heater having a double glass tube structure. In the defrosting heater of the double glass tube structure, the inner glass tube and the outer glass tube are sealed at the same position in the axial direction of the glass tube, so the structure of the sealing cap was complicated. Inner glass tube, outer glass tube A becomes to manufacture a sealing cap, it becomes the structure is simple compact sealing cap, cost cheaper, can be provided inexpensively defrosting heater.

  In the present invention, since the outer sealing plug for sealing the outer glass tube end opening is provided with an opening for releasing thermally expanded air during heating, even if there is an ignition or explosion in the outer glass tube It has a fire extinguishing distance that prevents the fire from spreading to the outside.

  Further, in the present invention, since the heat radiation fin is provided on the inner glass tube surface not surrounded by the outer glass tube, the heat radiation at the end portion of the inner glass tube is promoted and the temperature of the central portion of the inner glass tube is lowered.

  Furthermore, in the present invention, since the length of the outer glass tube is set to be 40 mm or shorter than the length of the inner glass tube, it is possible to specify a region where the heat dissipation effect is remarkable.

  Furthermore, in the present invention, since the surface temperature of the inner glass tube is less than 394 ° C., there is no danger of ignition or explosion even if a flammable refrigerant enters the outer glass tube.

  The present invention will be described in detail below based on specific embodiments shown in the accompanying drawings.

  The present invention includes an inner glass tube, a heater wire inserted through the inner glass tube, an inner sealing cap that seals the inner glass tube end opening, and a coil portion of the heater wire that is loosely inserted into the inner glass tube. A defrosting heater for a household refrigerator, comprising an outer glass tube that surrounds the outer periphery and an outer sealing plug that seals the outer glass tube end opening.

  FIG. 1 shows a specific embodiment of claim 1 of a defrosting heater for a household refrigerator according to the present invention.

  The present invention includes an inner glass tube 1, a heater wire 2 inserted through the inner glass tube 1, an inner sealing cap 3 that seals the end opening of the inner glass tube 1, and the inner glass tube 1. The outer glass tube 5 that surrounds the outer periphery of the coil portion 4 of the heater wire 2 and the outer sealing plug 6 that seals the end opening of the outer glass tube 5.

  The inner glass tube 1 is a quartz glass tube having a high heat transmittance, and has an outer diameter of 10.5 mm and a wall thickness of 1.0 mm.

  The heater wire 2 is a nichrome wire or other heat transfer wire, and a coil portion 4 having an effective heat generation length is usually formed in the central portion, and a so-called cold end straight end portion 7 is formed at both ends of the coil portion 4.

  The inner sealing cap 3 that seals the end opening of the inner glass tube 1 is made of silicon rubber.

  The outer glass tube 5 is a quartz glass tube having a high heat transmittance and an outer diameter of 20 mm and a wall thickness of 1.5 mm.

  The outer sealing plug 6 that seals the opening of the outer glass tube is made of silicon rubber.

  A specific embodiment of claim 2 of the defrosting heater of the domestic refrigerator of the present invention is shown in FIG. FIG. 2 shows two views, a front view and a sectional view of the outer sealing plug.

  According to the second aspect of the present invention, the outer sealing plug 6 that seals the opening at the end of the outer glass tube 5 is provided with the opening 11 that discharges the expanded air during heating.

  The outer sealing plug 6 is fitted between the inner surface of the outer glass tube 6 and the outer surface of the inner glass tube 1, and the outer glass tube 5 is mounted on the outer periphery and the inner glass tube 1 is mounted on the inner periphery. The tip is formed in a taper 12 for easy insertion.

  On the outer periphery of the outer sealing plug 6, there is an opening 11 that communicates from the outer end surface to the inner end surface so as to have a flame extinguishing distance that prevents the flame from propagating to the outside even if ignition or explosion occurs in the outer glass tube 5. Engrave.

  FIG. 3 shows a specific embodiment of claim 3 of the defrosting heater of the household refrigerator of the present invention.

  According to the third aspect of the present invention, the radiation fins 13 are provided on the surface of the inner glass tube 1 that is not surrounded by the outer glass tube 5.

  The radiating fin 13 promotes heat radiation at the end of the inner glass tube 1 by spiraling the outer surface of the inner glass tube 1 with a metal strip such as aluminum having good thermal conductivity, for example, and at the same time lowers the temperature. The temperature at the center of the glass tube 1 is also lowered.

  FIG. 4 shows a specific embodiment of claim 4 of the defrosting heater of the household refrigerator of the present invention.

  In the fourth aspect of the present invention, the length of the outer glass tube 5 is set to be 40 mm or shorter than the length of the inner glass tube 1.

When the length of the left side of the inner glass tube 1 not covered by the outer glass tube 5 is L ₁ , and the length of the right side of the inner glass tube 1 not covered by the outer glass tube 5 is L ₂ , the outer glass tube 5 Both end portions of the inner glass tube 1 that are not covered with can be made equal (L ₁ = L ₂ ), or one end portion can be set slightly longer than the other end portion. If the end portion of the inner glass tube 1 is not exposed to a certain extent (L ₁ + L ₂ > 40 mm), there is no significant heat dissipation effect.

  FIG. 5 shows a specific embodiment of claim 5 of the defrosting heater of the household refrigerator of the present invention.

  In the invention of claim 5 of the present invention, as shown in FIG. 5, the surface temperature of the inner glass tube 1 is set to less than 394 ° C.

  FIG. 6 shows a graph based on measured data of a conventional defrost heater having a double glass tube structure and a defrost heater in which only the outer periphery of the coil portion of the heater wire of the present invention is covered with an outer glass tube.

  FIG. 6 is a graph showing a comparison between the present invention in which only the outer periphery of the heater wire coil portion of the inner glass tube heater is surrounded by a glass tube, the present invention in which fins are further installed in the linear portion of the coil end, and the conventional glass double tube heater. Give an explanation.

  In the graph of FIG. 6, the horizontal axis represents the length from the center of the heater, and the vertical axis represents the glass tube surface temperature. The central portion of the heater is the central portion of the heat generating coil, the heater coil end portion is the coil end, and the cold end middle is the middle of the coil linear portion.

  Since the graph appears symmetrically with respect to the center of the heater, only half of it is shown for clarity.

  As apparent from FIG. 6, the conventional double tube heater has an inner glass tube temperature of 394 ° C. or higher, but under the same conditions, the heater of the present invention has a temperature of 394 ° C. or lower, improving safety against ignition and explosion. .

It is a front view of the concrete one Example of Claim 1 of the defrost heater of the domestic refrigerator of this invention. It is one specific example of Claim 2 of the defrosting heater of the domestic refrigerator of the present invention, and is a two-view drawing of a front view and a sectional view of the outer sealing plug. It is a front view of one specific Example of Claim 3 of the defrost heater of the domestic refrigerator of this invention. It is a front view of one specific Example of Claim 4 of the defrost heater of the domestic refrigerator of this invention. It is a front view of one specific Example of Claim 5 of the defrost heater of the household refrigerator of this invention. It is a graph of the measurement data of the defrost heater of the conventional double glass tube structure, and the defrost heater which covered only the coil part outer periphery of the heater wire of this invention with the outer side glass tube. It is a longitudinal cross-sectional view which shows the outline | summary of the conventional household refrigerator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inner glass tube 2 ... Heater wire 3 ... Inner sealing cap 4 ... Coil part 5 ... Outer glass tube 6 ... Outer sealing plug

Claims (5)

  An inner glass tube, a heater wire inserted through the inner glass tube, an inner sealing cap that seals the inner glass tube end opening, and an outer side that loosely inserts the inner glass tube and surrounds the outer periphery of the coil portion of the heater wire A defrosting heater for a household refrigerator comprising a glass tube and an outer sealing plug for sealing the outer glass tube end opening.   The defrosting heater for a household refrigerator according to claim 1, wherein an opening for releasing thermally expanded air during heating is provided in an outer sealing plug that seals the outer glass tube end opening.   The defrosting heater for a household refrigerator according to claim 1 or 2, wherein heat radiation fins are provided on the inner glass tube surface not surrounded by the outer glass tube.   The defrost heater for a household refrigerator according to claim 1, wherein the length of the outer glass tube is set to be 40 mm or shorter than the length of the inner glass tube.   The defrosting heater for a household refrigerator according to claim 1, 2, 3, or 4, wherein the surface temperature of the inner glass tube is less than 394 ° C.

Images