JPS6369176A - Defrosting heater - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a defrosting heating element used in a heat exchanger of a refrigerator-freezer.

Conventional technology In general, heat exchangers for refrigerators and freezers are made by arranging multiple thin metal plate fins in parallel, passing through the refrigerant pipes at right angles, and then expanding the refrigerant pipes to mechanically connect the fins and the refrigerant pipes. This can be obtained by fixing the refrigerant tube, and then forming the part of the refrigerant pipe where the fins are not arranged into a meandering shape so that the fin arrangement parts are straight and parallel to each other.

The thus obtained multi-stage heat exchanger, in which the fin rows are separated and independent, is set in the cooling duct of the refrigerator-freezer, and the compressor circulates the refrigerant through the refrigerant pipes and cools the freezer compartment and refrigerator compartment. Cooling can be achieved by forced circulation of airflow through a heat exchanger.

The return airflow from the freezer compartment or refrigerator compartment is mixed at the airflow inlet of the heat exchanger and passes through the heat exchanger, but the temperature of the return airflow from the freezer compartment is -20 to -15°C.

Since the temperature of the return airflow from the refrigerator compartment is 5 to 8℃ and the humidity is high, a large amount of frost forms on the surfaces of the fins and refrigerant pipes on the airflow inflow side of the heat exchanger, and if cooling operation continues as it is, it will cause damage. This causes clogging between the fins and significantly reduces cooling efficiency. Because of these things.

It is necessary to attach a heating element to a heat exchanger and defrost it regularly two to three times a day. When defrosting is performed using a heating element, defrosting must be completed efficiently in a short period of time in order to prevent food stored in the freezer from deteriorating. Further, since the refrigerator-freezer is used while being continuously energized for a long period of time, it is important to keep the power consumption of the nine heating elements to the necessary minimum.

Hitherto, this type of heating element has been proposed in Japanese Patent Publication No. 58-9911 and Japanese Patent Application Laid-Open No. 59-189273.

According to Japanese Patent Publication No. 58-9911, cuts for insertion of a heater are provided at opposite corners of a row of fins of a multi-stage heat exchanger, and a metal pipe is inserted between the cuts for insertion so as to be in thermal contact with each other. A pipe heater with a heater wire inserted inside was installed.

Further, according to Japanese Patent Application Laid-Open No. 59-189273, U-shaped notch grooves are formed in the plurality of fins and side plates of the heat exchanger, and the heating element 9 is a heating resistor having a positive temperature coefficient,
A planar heating element is provided with an external material such as an aluminum plate with good thermal conductivity through an insulating layer, and the planar heating element is inserted into the notched groove so as to be perpendicular to the plurality of fins. and installed it.

Problems to be Solved by the Invention However, conventional defrosting heating elements have the following drawbacks. That is, in Japanese Patent Publication No. 58-9911, the pipe heater is attached in a meandering manner to the opposite corner portions of the fins, which has the first drawback.

(1) The contact area between the pipe heater and fins is small.

Also, there is about 20% of the area that does not come into contact with the fins.

This is because defrosting must be performed by raising the surface temperature of the pipe heater, and convection loss increases.

If the temperature inside the cooling duct is raised too much, the next cooling operation will take extra time, and the food in the freezer compartment will likely deteriorate.

(2) Since the pipe heater is formed in a serpentine shape and attached to the corner of the fin, it is not possible to finely defrost areas with a lot of frost and areas with a little frost, so the defrosting time becomes longer and the power consumption is reduced. There will be more.

(3) Frost that does not completely melt during defrosting falls below the heat exchanger, so it is necessary to install a gutter-like heater underneath to defrost again, making the structure complex and increasing costs. It gets expensive.

Furthermore, according to Japanese Unexamined Patent Publication No. 59-189273, a U-shaped cutout groove is provided in the fins and side plates, and a planar heating element is inserted therein, resulting in the ninth defect.

(1) When installed in a multi-stage heat exchanger, the width of the nine-sided heating element becomes too narrow due to the narrow gaps between each stage of the fin rows, making it impossible to obtain enough heat generation capacity to complete defrosting in a short time. , the defrosting time becomes longer or the number of defrosting cycles is forced to increase, resulting in deterioration of frozen foods and increased power consumption.

(2) Planar heating elements have the characteristic that their calorific value increases as the temperature decreases, but in the temperature range of -30 to 0°C, the calorific value is almost saturated. There is not enough heat generation capacity to efficiently defrost the fin portion in a short time.

(3) A separate gutter heater is required to melt the debris during defrosting, which complicates the structure and increases cost.

Means for Solving the Problems The present invention has been made in order to eliminate the above-mentioned drawbacks.The present invention has been made in order to eliminate the above-mentioned drawbacks. The thin metal plate is bent into a substantially U-shape so that the thin plate is on the inside, and the metal thin plate is pressure-formed so as to enclose and closely fit the cord-shaped heating element, and is thinner than the thickness of the heat equalizer.

Function: The defrosting heating element of the present invention is constructed by bending the one-sided heating element configured as described above into a U-shape and setting it on both sides of the heat exchanger.

(1) Since the contact area with the fins is large and the surface temperature can be kept low, convection loss is small and efficient defrosting can be achieved.

(2) Cord-shaped heating elements can be precisely arranged to match the frost formation.

(3) Since the thin metal plate is thinner than the heat equalizer, it is easy to bend into a U-shape, so a cord-shaped heating element is installed using the U-shaped bent part as a seed part to remove fallen frost again. Frost can occur.

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

FIG. 1 shows 9 heating elements for defrosting of the present invention, 1 is a cord-shaped heating element arranged in a meandering manner, 5 is a cord-shaped heating element 1
6 is a thin metal plate such as aluminum foil having a thickness of 0.06 to α1■ with good thermal conductivity, and 7 is a heat-adhesive coating layer provided on the outermost layer of A heat sealing layer 8 is made of a material that can be laminated and welded by thermocompression bonding to the covering layer 5, and a cord-shaped heating element 1 arranged in a meandering manner is fixed to the thin metal plate 6 by a heat sealing layer 7. The obtained heater unit 9 is a thermally conductive material that is integrally bonded to the heat-sealing layer 7 after the heater unit 8 is pressure-formed from the metal thin plate 6 side and the metal thin plate 6 is enclosed and tightly attached to the cord-shaped heating element 1. 10 is a lead wire connected to the cord-shaped heating element 1 at the connector 11, and 12 is the heater unit 8 and the heat equalizer 9 integrated. A bent part formed into a substantially U-shape so as to be parallel to the long straight part 1a of the cord-like heating element 1 in which connected planar bodies are arranged in a meandering manner; 16 is a seed part formed by the bent part 12; 14;
15 is an airflow inlet for return airflow from the freezer compartment and the refrigerator compartment.

FIG. 2 shows the heater unit 8 of the defrosting heating element, in which 1 is a cord-shaped heating element, 2 is a core thread of the cord-shaped heating element made of heat-resistant fibers such as polyester or glass, and 3
4 is a heating resistance wire made of copper, nichrome, etc. wrapped around the outer circumference of the core yarn 2; 4 is made of vinyl chloride, silicone rubber, etc., which is extruded into tubing around the outer periphery of the core yarn 2 and the heating resistance wire 3. A heat-fusible coating layer 6 made of an olefin composition such as polyethylene, vinyl acetate, thermoplastic nidistomer, etc., formed into a tube by extrusion molding around the outer circumference of the insulating layer 4, has good thermal conductivity; 7 is a thin metal plate such as soft aluminum foil having extensibility, e.g. This is a heat-adhesive layer made of polyethylene, vinyl acetate, etc. A heat-sealing layer 7 is placed on the cord-shaped heating element 1 which is arranged in a meandering manner in a predetermined pattern.
The thin metal plate 6 is placed so that the cord faces toward the cord-shaped heating element 1, and the coating layer 5 and the heat-sealing layer 7 are welded together by thermocompression bonding at a temperature of 120 to 250°C for 1 to 10 seconds. A heater unit 8 is obtained.

Figure 3 shows a part of the cross section of the defrosting heating element.
1 is a cord-shaped heating element, 5 is a thermally adhesive coating layer provided as the outermost layer of the cord-shaped heating element 1, and 6 is an aluminum material with a thickness of 0.03 to 11 with good thermal conductivity and stretchability. A thin metal plate such as foil, 7 is a heat-sealing layer laminated on the surface of the thin metal plate B and welded to the covering layer 5 by thermocompression bonding.

Reference numeral 9 denotes a heat-uniforming body made of aluminum or the like having a thickness of α2 to 0.5 m and having good thermal conductivity, which is integrally joined to the thin metal plate 6 by a heat-sealing layer 7. The thin metal plate 6 is made with a hard surface on the cord-shaped heating element 1 side and an elastic body such as a rubber foam on the side of the thin metal plate 6 in a process in which no heat is applied before being integrally joined to the heat equalizing body 9 by thermocompression bonding. By intervening and pressurizing at a pressure of 50 to 3001'4/d.

The cord-shaped heating element 1 is enclosed and tightly attached to the outer periphery of the cord-shaped heating element 1.

Further, the thin metal plate 6 is soft and thinner than the thickness of the heat-uniforming body 9, and is bent with the thin metal plate 6 inside.

FIG. 4 shows a state in which the defrosting heating element of the present invention is incorporated into a heat exchanger 16, in which fins 17 are arranged at predetermined intervals, 18 are orthogonal to the fins 17, and fins 17 are arranged at predetermined intervals. It is a refrigerant pipe formed by bending the part where is not provided in a serpentine shape, and is integrally joined with a thin metal plate 6 and a heat equalizing body 9 with a cord-shaped heating element 1 arranged in a meandering manner, and A defrosting heating element is bent in a substantially U-shape at the bent portion 12 so as to be on the inside of the fin 17, and is fixed in contact with the fin 17. The convex portions of the thin metal plate 6 that tightly contain the cord-shaped heating element 1 are arranged at the corners of the multi-stage fins 17 and the notches 19 provided on both sides of the fins 17,
The heat generated from the cord-shaped heating element 1 is diffused between the thin metal plate 6 and the heat equalizer 9, making the temperature distribution almost uniform, and at the same time, it is also diffused to the fins 17 in contact with the thin metal plate 6 and removed. Demonstrates frost function. The seed part 13 formed by being bent into a substantially U-shape receives fallen frost and at the same time defrosts it again by the cord-shaped heating element 1 in that part and drains water from the drain port 14.

Also, since the return airflow from the freezer and refrigerator compartments enters from the airflow inlet 15 and circulates through the heat exchanger 16 while being mixed, the portions located on the fins 17 where a large amount of frost forms on the airflow inflow side are The meandering arrangement pitch of the cord-shaped heating element 1 is set close.

Next, the operation of this embodiment having the above configuration will be explained.

Since the cord-shaped heating element 1 is integrally joined with a thin metal plate 6 having good thermal conductivity and a heat equalizing element 9, and the thin metal plate 6 is a planar heating element that includes the cord-shaped heating element 1 and is in close contact with the cord-shaped heating element 1, the cord Since heat can be extracted efficiently from the cord-shaped heating element 1, even if a high wattage of heat is generated, the cord-shaped heating element 1 will not undergo thermal aging or the surface temperature will rise too much and convection loss will not increase. By attaching this heating element to the heat exchanger, the fin 1
Since the side surface of 7 is in contact with the surface of the thin metal plate B, the heat conduction efficiency is good and defrosting can be completed quickly.

Therefore, since the temperature rise in the cooling duct can be minimized, the ninth cooling operation can be carried out smoothly and efficiently.

Since the cord-shaped heating element 1 can be arranged in a meandering manner in accordance with the frost distribution of the heat exchanger 16, the portion that has been defrosted will not be overheated, and power can be saved.

The thin metal plate 6 is made of a soft and stretchable material.

Since the heat equalizer 9 is also thin, it can be easily bent into a substantially U-shape. By bending it into a substantially U-shape, a machine part 13 can be formed, in which the cord-shaped heating element 1 is disposed, and a drain port 14 is provided to receive the frost that has formed from the heat exchanger 16 and regenerate it. Can be defrosted. Since this has a simple structure in which a sheet of sheet is bent into a U-shape, it can be manufactured at low cost.

In the cord-shaped heating element 1 of the present invention, by providing the heat-fusible coating layer 5 on the outermost layer, the workability can be improved by forming the heater into a unit, and the arrangement pattern can always be made precise. Since it can improve the adhesion with the thin metal plate 6 and the heat equalizer 9, it has the function of increasing heat conduction characteristics. In the embodiment, an example was shown in which the insulating layer 4 and the covering layer 5 were separate; however, the present invention is not limited to this, and the covering layer 5 may be made of an insulating heat-fusible material, such as an olefin-based material. It may also be a thermoplastic elastomer. Further, the hardness of the coating layer 5 is determined based on conditions that allow for good pressure forming when the thin metal plate 6 is closely attached to the cord-shaped heating element 1.

The rubber hardness is preferably 50 to 120.

The heat-sealing layer 7 is laminated and bonded to the thin metal plate 6, and has the property of being welded to the covering layer 5 and the heat equalizer 9 by thermocompression bonding, so that it is easy to form a heater unit and to join the heat equalizer 9. Although it can be done rationally, the present invention is not limited thereto.
A heater unit 8 made of a film made of the same material may be prepared in advance, and this heater unit 8 may be sandwiched between the thin metal plate 6 and the heat equalizer 9 and integrally joined. in this case,
Before thermocompression bonding, it is necessary to apply pressure from the side of the thin metal plate 6 through an elastic body to shape the thin metal plate 6 so as to enclose the cord-shaped heating element 1 and bring it into close contact with the thin metal plate 6.

Effect of the invention According to the present invention, the following effects are achieved.

Its industrial utility value is great.

(1) Defrosting can be completed in a short time with high wattage and low convection loss, so frozen foods do not deteriorate and power is saved.

(2) Defrosting efficiency is high because heating can be performed in accordance with the frost distribution.

(3) Re-defrosting of frost from the heat exchanger can be done at low cost with a simple structure.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway perspective view of an embodiment of the defrosting heating element of the present invention, Fig. 2 is a perspective view of a heater unit used in this embodiment, and Fig. 3 is a cross-section of the main part of this embodiment. FIG. 4 is a schematic cross-sectional view of this embodiment attached to a heat exchanger. 1... Cord-shaped heating element, 6... Metal thin plate. 9... Soaking body.

Claims (1)

[Claims] A cord-shaped heating element (1) is connected to a thin metal plate (6) and a heat equalizing element (9).
In the defrosting heating element, which is integrally joined with the metal thin plate (6) arranged in a meandering manner between the cord-shaped Heating element (1
), and is thinner than the thickness of the heat equalizer (9).