WO2004074751A1

WO2004074751A1 - Defrosting heater and method of manufacturing the same

Info

Publication number: WO2004074751A1
Application number: PCT/JP2004/001908
Authority: WO
Inventors: Yukio Morikawa; Ichiro Onishi; Toshiki Maeda
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2003-02-20
Filing date: 2004-02-19
Publication date: 2004-09-02
Also published as: JP3580307B2; TW200417714A; TWI254784B; JP2004263889A; CN100416195C; CN1754075A

Abstract

A defrosting heater capable of removing, by heating, frost adhered to an evaporator in a refrigerating cycle, comprising a glass tube having an opening at the end thereof, a heater wire stored in the glass tube, a plug covering the opening of the glass tube and having a hole communicating the inside and the outside of the glass tube formed therein, a lead connected to the heater wire through the hole in the plug, and a valve installed in the plug and flowing gas in the glass tube to the outside. The temperature of the glass tube is not so raised in the defrosting heater. Accordingly, even if refrigerant in the refrigerating cycle is inflammable, the glass tube is not heated to the ignition temperature of the refrigerant or higher. As a result, there is no need to consider the suppression of the rise of the temperature.

Description

Defrost heater and method for manufacturing the same

The present invention relates to a defrosting heater and a method for manufacturing the heater, which are used for a cooling device such as a refrigerator, and which defrosts frost adhering to a cooler of a refrigeration cycle in which a combustible refrigerant is sealed. Background art

A conventional defrosting heater for defrosting frost adhering to a cooler of a refrigerating cycle of a refrigerator is disclosed in Japanese Patent Application Laid-Open No. 8-54172.

FIG. 8 is a cross-sectional view of a main part of a refrigerator 1 including a conventional defrost heater 15. The refrigerator 1 has a freezer compartment 2, a refrigerator compartment 3, a freezer compartment door 4, a refrigerator compartment door 5, a partition wall 6 separating the freezer compartment 2 and the refrigerator compartment 3, and an air inside the freezer compartment 2. , A suction port 8 for sucking air in the refrigerator 3, an outlet 9 for discharging cool air, an evaporator 10, a fan 11 for circulating cool air, and an evaporator 10. And a partition wall 12 for partitioning from the freezer compartment 2. Below the evaporator 10, a defrost heater 15 with a coiled nichrome wire covered with a glass tube, and the water generated by the defrost directly drops on the defrost heater 15 to contact. A roof 16 is provided to prevent the evaporative noise generated when the vehicle is in use, and a metal bottom plate 17 is provided. Water collected in tub 13 is drained through drain 14. The operation of the defrost heater 15 will be described. The evaporator 10 is cooled by the refrigerant flowing therein, and cools the freezing room 2 and the refrigerator room 3. The fan 11 sends the air heated in the freezer 2 and the refrigerator 3 from the suction port 7 and the suction port 8 to a cooling chamber (not shown). The air is cooled by heat exchange in the evaporator 10 and sent to the freezer 2 from the discharge port 9 by the fan 11. The air is sent from the freezer compartment 2 to the refrigerator compartment 3 through a port (not shown) communicating with the refrigerator compartment 3.

The air exchanged in the evaporator 10 is included in the high-temperature outside air that flows in by opening and closing the door 4 of the freezer compartment 2 and the door 5 of the refrigerator compartment 3 and the food stored in the refrigerator compartment 2 and the refrigerator compartment 3. Evaporate It is air humidified by the moisture. Therefore, the moisture in the air adheres as frost to the evaporator 10 which is lower in temperature than the air, and as the amount increases, the heat transfer between the evaporator 10 and the air is hindered. Further, the attached frost acts as ventilation resistance, and the amount of air passing through the evaporator 10 is reduced, so that the heat transmission rate is reduced and insufficient cooling occurs. Therefore, the nichrome wire of the defrost heater 15 is energized before the cooling becomes insufficient. When energization of the nickel wire is started, heat rays are radiated from the nichrome wire to the evaporator 10 and its peripheral parts. At this time, a part of the heat ray radiated to the bottom plate 17 is reflected from the bottom plate 17 to the chromium wire, and the others are reflected toward the evaporator 10 and peripheral parts. The heat reflected toward the evaporator 10 and surrounding components melts the frost that has arrived near the evaporator 10, the tub 13, and the drain 14 into water.

Some of the water generated in this way falls directly into the tub 13, and the rest falls into the tub 13, avoiding the defrosting night 15 by the roof 16, and is discharged from the drain 14. You.

In the conventional defrosting method described above, the temperature of the glass tube covering the nichrome wire as well as the surface of the nichrome wire is extremely high. The temperature of the glass tube rises further because the bottom plate 17 is near the defrost heater 15 and reflects a part of the heat rays radiated from the defrost heater 15 to the defrost heater 15. .

The refrigerant may leak from a pipe installed in the evaporator 10 or a part communicating with the inside of the refrigerator. When the refrigerant is flammable, the temperature of the glass tube of the defrost heater 15 must not exceed the ignition temperature of the refrigerant. Disclosure of the invention

The defrost heater heats and removes frost adhering to the evaporator of the refrigeration cycle. During the defrosting operation, a glass tube with an opening at the end, a heater wire housed in the glass tube, and a stopper that covers the opening of the glass tube and has a hole formed to communicate the inside and outside of the glass tube And a lead wire connected to the heater wire through the hole of the stopper, and a valve provided on the stopper for discharging gas inside the glass tube to the outside.

The temperature of the glass tube does not rise so much with the defrost heater. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a sectional view of a main part of a defrosting heater according to an embodiment of the present invention.

FIG. 2 shows a refrigerator refrigeration system using a defrost heater according to the embodiment. FIG. 3 is an exploded view of the defrost heater according to the embodiment.

FIG. 4 shows another defrost heater according to the embodiment.

FIG. 5 shows still another defrost heater according to the embodiment.

FIG. 6 is a sectional view of a main part of the defrosting heater shown in FIG.

FIG. 7 shows still another defrost heater according to the embodiment.

FIG. 8 is a cross-sectional view of a refrigerator provided with a conventional defrost heater. BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a cross-sectional view of a main part of a defrost heater 20 according to Embodiment 1 of the present invention. The defrosting heater 20 incorporates a heater wire 21 in which a resistance wire is formed in a coil shape. The vicinity of both ends of the heater wire 21 has a linear connection end 21a. The glass tube 23 covering the heater wire 21 has an outer diameter of about 10.5 mm and has a cylindrical shape with both ends open. The glass tube 24 that covers the glass tube 23 has an outer diameter of about 20 mm and has a cylindrical shape with both ends opened. A lead wire 26 is connected to the heater wire 21 via a conductive sleeve 28. The silicone rubber stopper 22 covers the open ends of the glass tubes 23 and 24. The lead wire 26 is connected to the heater wire 21 through a hole 22 a provided in the stopper 22. The stopper 22 is provided with a hole 2 2b communicating with the interior space 23 a of the glass tube 23 and a space 24 a surrounded by the glass tube 23 and the glass tube 24 to the outside of the stopper 22. ing. Hole 22b has a minimum cross-sectional area of 7.1 square millimeters or less. The rubber valve 25 is attached to the cylinder 27 so as to close the opening 27A of the cylinder 27 having the bottom in the hole 22b. The valve 25 acts as a check valve that opens only in one direction with a predetermined pressure difference.

The stopper 22 has a simple structure in which a predetermined hole 22b is closed by a valve 25 in advance, so that the shape of the stopper 22 is not complicated and the cost is low.

FIG. 2 shows a refrigeration system of a refrigerator using the defrost heater 20 according to the embodiment. A refrigeration cycle consisting of a compressor 60, a condenser 61, a pressure reducing mechanism 62 and an evaporator 10 is filled with a flammable refrigerant, and the compressor 60, a condenser 61, a pressure reducing mechanism 62 and an evaporator 1 Cycle 0. The refrigeration cycle is provided in a cooling device, for example, a refrigerator, and cools a cooling room of the refrigerator.

The operation of the defrost heater .20 configured as described above will be described. The evaporator 10 is cooled by the refrigerant sent by the operation of the compressor 60. The air in the refrigerator passes through the cooled evaporator 10 by the fan 11 operating at the same time as the compressor 60, and cool air exchanged with the evaporator 10 is discharged into the refrigerator. The compressor 60 stops after a predetermined operation time has elapsed. At the same time as the stop, the heater wire 21 is energized through the lead wire 26, and the defrost heater 20 generates heat.

Due to the heat generated by the heater wire 21, part of the radiant heat rays is directly transmitted to the outside, but the others are transmitted to the glass tubes 23 and 24, and the temperature of the surface of the glass tube 24 is ignited by the flammable coolant The temperature rises to a temperature lower than the temperature, and the heat is radiated to the outside, and the defrosting of peripheral parts of the evaporator is performed safely.

At this time, in the internal space 23 a of the glass tube 23 and the space 24 a surrounded by the glass tube 23 and the glass tube 24, the gas expands due to a rise in temperature. However, the valve 25 is deformed by the inflated air, and the inflated air is discharged from the valve 25 through the hole 22b, so that the pressure does not increase in the spaces 23a and 24a. The glass tubes 23 and 24 are not damaged, and the stopper 22 cannot be removed.

Thereafter, when the power supply to the heater wire 21 is stopped and cooling is started again, the inside of the glass tubes 23 and 24 is reduced in pressure due to a decrease in temperature. Since the depressurized state is maintained inside the defrost heater 20, the valve 25 prevents the inflow of outside air. Therefore, even if the flammable refrigerant exists around the defrost heater 20, the flammable refrigerant hardly flows into the defrost heater 20, and the possibility of igniting the refrigerant is extremely low.

If flammable refrigerant flows into the glass tube and ignites with the heater wire 21, the valve 25 opens slightly when the pressure inside the glass tube exceeds a predetermined pressure, and the pressure is too high. The valve 25 shuts off the flame and prevents the flame from spreading to the outside.

The hole 22b has a very small minimum cross-sectional area of 7.1 square millimeters or less, so that the flame cannot pass through it. Therefore, if the valve 25 is missing, the flame cannot propagate outside since the flame cannot pass through the hole 22b. The valve 25 is attached to the stopper 22 via a bottomed cylinder 27. The valve 25 is made of rubber. If the valve 25 is directly attached to the rubber stopper 22, the position of the valve 25 is difficult to determine, and the pressure at which the valve 25 opens may vary. Further, it is difficult to fix the valve 25 directly to the stopper 22. When the valve 25 is mounted on the cylinder 27 made of a material harder than rubber, the opening pressure thereof is stabilized, and the cylinder 27 can be easily fixed directly to the stopper 22. The opening pressure of the valve 25 can be changed by changing the dimensions of the mounting part of the valve 25 in the cylinder 27, so that the heating value of the defrost heater 20 and the glass tubes 23, 24 The optimal pressure can be set according to the internal volume.

FIG. 3 is an exploded view of the defrost heater 20. The diameter D 1 of the hole 22 a of the stopper 22 is smaller than the diameter D 2 of the lead wire 26. Therefore, the stopper 22 holds the lead wire 26 in a tightened state, and the outside air and the refrigerant do not flow into the defrost heater 20 through the hole 22a.

The lead wire 26 has a soft coating 26 A of silicon rubber or the like, so that it is difficult to pass through the hole 22 a. A sleeve 28 is attached to the end of the lead wire 26, and the lead wire 26 is easily inserted into the hole 22a by passing the sleeve 28 through the hole 22a.

FIG. 4 shows another defrost heater 120 according to the embodiment. In the defrosting heater 20 shown in Fig. 1, the outside of the surface of the glass tube 24 is exposed, but as shown in Fig. 4, the outside of the glass tube 24 is covered with a metal tube 50. You may. The metal tube 50 serves as an outer shell to prevent water from directly splashing on the glass tube 24.

FIG. 5 shows another defrost heater 220 according to the embodiment. Although the defrost heater 20 shown in FIG. 1 has a double structure with the glass tubes 23 and 24, the defrost heater 220 has no glass tube 24 and the glass tube 23 is exposed. are doing. If the surface temperature is lower than the ignition point of the flammable refrigerant, the same effect can be obtained with only one glass tube 23.

FIG. 6 is a sectional view of a main part of the defrost heater 220 shown in FIG. Silicon rubber stopper 1 2 2 covers the open end of glass tube 23. The lead wire 26 is connected to the hysteresis line 21 through a hole 122 a provided in the stopper 122. The plug 122 is provided with a hole 122 b communicating from the internal space 23 a of the glass tube 23 to the outside of the plug 122. Hole 122b has a minimum cross-sectional area of less than 7.1 square millimeters. Rubber valve Reference numeral 25 is attached to the cylinder 27 so as to close the opening 27A of the cylinder 27 having the bottom in the hole 122b. The valve 25 acts as a check valve that opens only in one direction with a predetermined pressure difference.

FIG. 7 shows still another defrost heater 320 according to the embodiment. In the defrosting heater 220 shown in FIG. 6, the outside of the surface of the glass tube 23 is exposed, but as shown in FIG. 7, the outside of the glass tube 23 is covered with a metal tube 50. You may. The metal tube 50 acts as an outer shell to prevent water from directly splashing on the glass tube 23.

Furthermore, if the surface of the metal tube 50 is colored black, for example, in FIGS. 4 and 7, the radiant heat from the metal tube 50 increases, and the defrost heaters 120, 320 are defrosted. Performance is improved. Further, since the temperature rise on the surfaces of the defrost heaters 120 and 320 can be suppressed, the metal tube 50 is effective for keeping the surface temperature below the ignition temperature of the flammable refrigerant. .

Further, in the embodiment, the refrigerator has been described as an apparatus using the defrost heater 20, but this apparatus can also use the defrost heaters 120, 220, and 320 in the same manner. This device is not limited to a refrigerator, but can be widely applied to a cooling storage provided with an evaporator, for example, a showcase or a vending machine provided with a refrigeration cycle filled with a flammable refrigerant. Industrial applicability

The defrost heater heats and removes frost adhering to the evaporator of the refrigeration cycle. The defrost heater has a glass tube that houses the heater wire, and the temperature of the glass tube does not rise so much. Therefore, even if the refrigerant in the refrigeration cycle is flammable, the glass tube does not rise above the ignition temperature of the refrigerant, and there is no need to consider suppressing the temperature rise.

Claims

The scope of the claims

1. A defrosting heater for heating and removing frost adhering to an evaporator of a refrigeration cycle, the first glass tube having an opening at an end,

A light line stored in the first glass tube;

A stopper that covers the opening of the first glass tube and has a first hole formed therein that communicates the inside and the outside of the first glass tube;

A lead wire connected to the heater wire through the first hole of the stopper, and a valve provided on the stopper for allowing the gas inside the first glass tube to flow out to the outside;

With defrosting heat.

2. The defrosting heater according to claim 1, wherein the valve is deformed when the inside of the first glass tube becomes higher than a predetermined pressure.

3. The stopper is provided with a second hole communicating the inside of the first glass tube with the outside of the first glass tube,

2. The defrost heater according to claim 1, wherein the valve closes the second hole.

4. The defrosting heater according to claim 3, wherein the second hole has a cross-sectional area large enough to prevent a flame from propagating.

5. The defrost heater according to claim 3, further comprising a cylinder inserted into the second hole, the cylinder having an opening, and the valve closing the opening of the cylinder.

6. The defrost heater according to claim 1, wherein the valve is a check valve that allows gas to flow only from the inside of the first glass tube.

7. The defrost heater according to claim 1, wherein a diameter of the first hole of the stopper is smaller than a diameter of the lead wire.

8. The defrost heater according to claim 1, further comprising a metal tube that houses the first glass tube.

9. The defrosting heater according to claim 8, wherein the surface of the metal tube is colored.

-evening.

10. A second glass tube having an opening at an end for accommodating the first glass tube therein,

The stopper covers the opening of the first glass tube and the opening of the second glass tube;

2. The valve according to claim 1, wherein the valve causes the gas inside the first glass tube and a gas in a space between the first glass tube and the second glass tube to flow out. 4. A defrosting heater according to item 1.

11. The defrosting heater according to claim 10, wherein the valve is deformed when the inside of the first glass tube and the second glass tube becomes higher than a predetermined pressure. .

1 2. The stopper includes: the inside of the first glass tube; and the space between the first glass tube and the second glass tube, outside the second glass tube. Communicating with the

Two holes are provided,

10. The defrost heater according to claim 10, wherein the valve closes the second hole.

13. The defrost heater according to claim 12, wherein the second hole has a cross-sectional area large enough to prevent a flame from propagating therein.

14. The defrost heater according to claim 12, further comprising a cylinder having an opening inserted into the second hole, wherein the valve closes the opening of the cylinder.

15. The valve according to claim 10, wherein the valve is a check valve that allows gas to flow out only from the inside of the first glass tube and the inside of the second glass tube. Defrost

1 10. The defrost heater according to claim 10, further comprising a metal tube for housing the second glass tube.

17. The defrost heater according to claim 16, wherein the surface of the metal tube is colored.

1 8. preparing a glass tube having an opening at an end, a stopper having a hole formed therein, a lead wire having a diameter larger than the hole, and a heater wire;

Covering the opening of the glass tube with the stopper;

Attaching a sleeve to the lead;

Passing the sleeve, on which the lead wire is attached, through the hole of the stopper;

Connecting the heater wire to the sleeve;

A method for manufacturing a defrost heater, comprising: