JPS6394580A - 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. It is obtained by fixing the refrigerant pipe, and further forming the refrigerant pipe in the part where the fins are not arranged into a meandering shape so that the arranged parts of the fins are straight and parallel to each other.

The so-called multi-stage heat exchanger, in which the fin rows obtained in this way are separated and independent, is set in the cooling duct of a 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 forcing 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 room 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, making it impossible to continue the trench cooling operation. If this continues, the fins will become clogged and the cooling efficiency will drop significantly. 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. Also,
Since refrigerator-freezers are used with continuous electricity for long periods of time, it is important to keep the power consumption of the nine heating elements to the minimum necessary.

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 7'C pipe heater was installed by inserting a heater wire into the pipe.

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 outer covering material such as an aluminum plate with good thermal conductivity via an insulating layer on the outer shell, and this planar heating element is inserted into the notched groove so as to be perpendicular to the plurality of fins. It was installed.

Problems to be Solved by the Invention However, the conventional defrosting heating element has the following drawbacks. That is, in Japanese Patent Publication No. 58-9911, the vibrator heater is attached to opposite corner portions of the fin in a meandering manner, resulting in the ninth defect.

0+ Non-contact part between the vibe heater and fins or about 20
%, it is necessary to defrost by raising the surface temperature of the vibrator heater, and as a result, the temperature inside the cooling duct increases too much, which takes extra time for the next cooling operation, and the food in the freezer compartment easy to deteriorate.

(2) Since the vibrator heater is formed in a meandering shape and is attached to the corner of the fin, and has a shape with regular intervals, it is not possible to perform detailed defrosting that corresponds to areas where there is a lot of frost formation and areas where there is little frost formation.

(3) During defrosting, unmelted frost falls below the heat exchanger, so it is necessary to install a gutter-like heater on the bottom 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.

fl) When installed in a multi-stage heat exchanger, the gap between each stage of the fin row is narrow, and the sheet heating element corresponding to the gap does not have enough heat generation capacity to complete defrosting in a short time. Longer time or more defrost cycles. As a result, frozen foods deteriorate and power consumption increases.

(2) The heating value of the sheet heating element is almost saturated in the temperature range of -30 to 0°C, so it is only possible to efficiently defrost the fins on the airflow inlet side where there is a large amount of frost in a short time. does not have the ability to generate heat.

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

An object of the present invention is to provide a defrosting heating element that eliminates the above-mentioned conventional drawbacks.

Means for Solving the Problems The present invention has the following nine configurations in order to achieve the object. In other words, the defrosting heating element according to the present invention has a cord-shaped heating element provided with a heat-fusible covering on the outermost part thereof, and a heat-fusible thin body provided on a metal thin plate-like body in an appropriate shape. Furthermore, the thin metal plate is integrally formed around the outer periphery of the cord-like heating element, and the thin metal plate is bent inside to form a substantially U-shape.

The working cord-like heating element is arranged on the metal thin plate-like body through a heat-sealed thin body in a shape corresponding to the frosted area.

They are integrated by pressure molding. Further, a thin metal plate is formed into a U-shape on the inside and fitted into the fins of the heat exchanger. The above configuration has a larger contact area with the fins than the conventional one, the cord-shaped heating element is carefully arranged to match the amount of frost, and has a re-defrosting function.

Example Hereinafter, nine embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the defrosting heating element 20 of the present invention, in which numeral 1 is a cord-shaped heating element arranged in a meandering manner, and numeral 5 is a cord-shaped heating element provided at the outermost part of the cord-shaped heating element 1. Heat-fusible covering, 6
is a metal thin plate-like body, such as aluminum foil, having a thickness of 0.03 to 0.1 mm and having good thermal conductivity.

7 is a heat-sealing thin body made of a material that is laminated in advance on the surface of the metal thin plate-like body B and has the property of being welded to the heat-sealing coating 5 by thermocompression bonding; 8 is a cord-shaped heating element arranged in a meandering manner; body 1
is fixed to the metal thin plate body 6 using the heat-sealed thin body 7, and then pressure molded from the side of the metal thin plate body 6 to surround and integrate the metal thin plate body 6 with the cord-shaped heating element 1. The heater unit is bent into a substantially U-shape so that the metal thin plate is on the inside, and 9 is an aluminum plate with a thickness of 0.03 to 2 mm with good thermal conductivity that is integrally joined or temporarily fixed to the heater unit 8. A diffusion holder such as a plate, a lead wire connected to the 10-piece cord-shaped heating element 1 at the connector 11, and 12 a long straight convex portion 1 of the cord-shaped heating element 1 arranged in a meandering manner.
13 is a bridge formed by the bend 12; 14 is a drain provided in the bridge 1'5 through which water generated by defrosting flows; Reference numeral 15 denotes an airflow inlet for return airflow from the freezer compartment and the refrigerator compartment, and the pitch density of the cord-shaped heating element 1 is approximately U-shaped bent portion 12.
Keep your sides close.

It is arranged so that the opposite side that does not have the bending part 12 is rough.

FIG. 2 shows the heater unit 8 of the defrosting heating element 20, in which 1 is a cord-shaped heating element, 2 is a core string of the cord-shaped heating element made of heat-resistant fibers such as polyester or glass, and 6 is a heat-generating resistance wire made of a metal wound around the outer circumference of the core thread 2; an insulating layer made of vinyl chloride, silicone rubber, etc., tubing formed by extrusion molding around the outer circumference of the four-wire core thread 2 and the heat-generating resistance wire 3; 5 is a small heat-fusible covering made of an olefin composition or a thermoplastic elastomer, which is formed into a tube around the outer periphery of the insulating layer 4 by extrusion molding.

6 has good thermal conductivity and extensibility, e.g. [103~l:1
1mm+ soft metal thin plate like aluminum foil, 7
It is a heat-sealing thin body made of a material such as olefin-based polyethylene, vinyl acetate, etc., which is laminated in advance with the metal thin plate-like body 6 by lamination processing and is welded to the heat-fusible covering body 5 by thermocompression bonding. .

A thin metal plate 6 is placed on the cord-shaped heating element 1 arranged in a meandering manner in a predetermined pattern so that the heat-sealable thin body 7 faces the cord-shaped heating element 1, and heated to 120 to 250°C. 1 at a temperature of
By thermocompression bonding for ~10 seconds.

The heat-fusible covering 5 and the heat-fusible thin body 7 are welded together.

The heater unit 8 in which the convex portion 1a is formed is obtained by pressure molding.

FIG. 3 shows the state in which the defrosting heating element 20 of this embodiment is assembled into the heat exchanger 16, in which fins 17 are arranged at predetermined intervals, and fins 18 are orthogonal to the fins 17 and fins 16 are arranged at predetermined intervals. 1
It is a refrigerant pipe formed by bending the part where no. , and the bent portion 1 is bent into a substantially U-shape so that the metal thin plate-like body 6 is on the inside.
A defrosting heating element bent at two points is brought into contact with the fins 17, and the diffusion holder 9 is fixed to a side plate 21 provided at a meandering portion of the refrigerant pipe 18. The surface 1a of the metal thin plate-like body B, which integrally surrounds the cord-like heating element 1, is fitted into the corners 17a of the multi-stage fins 17 and the notches 19 provided on both sides of the fins 17, Cord-shaped heating element 1
The heat generated is diffused between the metal thin plate body 6 and the diffusion holder 9 to make the temperature distribution almost uniform, and at the same time, it is also diffused to the fins 17 that are in contact with the metal thin plate body 6. Demonstrates defrosting function.

A bridge part 13 formed by being bent into a substantially U-shape receives the dropped boxes, and at the same time defrosts them again using a cord-shaped heating element 1 in that part and drains the water from a 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 builds up on the airflow inflow side are The meandering arrangement pitch of the cord-shaped heating element 1 is set close.

Next, the effects of the above configuration will be explained.

A planar heating element in which a cord-shaped heating element 1 is integrally joined with a metal thin plate-shaped body 6 having good thermal conductivity and a diffusion holder 9, and the metal thin plate-shaped body 6 surrounds and integrates the cord-shaped heating element 1. Because of this, heat can be extracted efficiently from the cord-shaped heating element 1, so even if a high wattage of heat is generated, the cord-shaped heating element 1
may undergo heat aging.

There is no possibility that the surface temperature will rise too much and convection loss will increase. By attaching this defrosting heating element 20 to the heat exchanger 16, the side portions of the fins 17 come into contact with the surface of the metal thin plate body 6, so that heat conduction efficiency is high and defrosting can be completed quickly. can. Therefore, since the temperature rise in the cooling duct can be minimized, the fifth cooling operation can be performed smoothly and efficiently.

This is because the convex portion 1a of the cord-shaped heating element 1 disposed portion provided inside the defrosting heating element 20 is fitted into at least one of the corners of the fin 17 or the notch 19.

Since heating can be performed in accordance with the frost distribution of the heat exchanger 16, the portions that have been defrosted are not overheated, and power can be saved.

The thin metal plate 6 is made of a soft material with good extensibility, and if the diffusion holder 9 has a weight of about α1 mg+ or less, it can be bent into a substantially U-shape even if the thickness is approximately the same. By bending it into a substantially U-shape, a bridge portion 16 can be formed, in which the cord-shaped heating element 1 is disposed and a drain port 14 is provided to connect the heat exchanger 1.
It is possible to receive a thin box of frost from 6 and defrost it again.

In addition, by providing the airflow inlet 15 at or near the bridge section 13, the return airflow from the freezer compartment and the refrigerator compartment is easily mixed in the space surrounded by the heat exchanger 16 and the bridge section 16, and the fins 17 The frost distribution becomes more uniform and the defrosting efficiency can be increased. Since these have a simple structure in which one sheet is bent into a U-shape, they can be manufactured at low cost.

Further, since the cord-shaped heating element 1 is provided with the heat-fusible covering 5 on the outermost part, the workability can be improved by forming the cord-shaped heating element 1 into a heater unit. The placement pattern can always be made accurately. It has the function of improving heat conduction properties because it can improve the adhesion with the metal thin plate-shaped body 6 and the dispersion holder 9. In the embodiment, an example was shown in which the insulating layer 4 and the heat-fusible covering 5 were separate.

The insulating layer 4 may be omitted if the heat-fusible covering 5 is made of a heat-fusible material having insulating properties, such as an olefin thermoplastic elastomer. In addition, the hardness of the heat-fusible covering 5 is determined to be 50 to 120 in terms of rubber hardness, in order to achieve good pressure molding when surrounding and integrating the thin metal plate 6 with the cord-shaped heating element 1. preferable.

Note that the heat-sealable thin body 7 is laminated and bonded to the metal thin plate-like body 6, and has the property of being welded to the heat-sealable coating 5 and the diffusion holder 9 by thermocompression bonding. However, other means 9, such as a heater unit consisting of a meandering cord-shaped heating element and a film made of the same material as the heat-sealing thin body 7, can be carried out rationally. The heater unit may be prepared in advance and then integrally joined by sandwiching the heater unit between the metal thin plate member 6 and the diffusion holder 9. Alternatively, the cord-shaped heating element 1 can be formed using two thin metal plates 6.
A thin metal plate 6 that becomes the inner side when folded into a substantially U-shape is press-molded and tightly attached around the cord-shaped heating element to form a unit, and the unit is diffused and held on the outside of this unit. A body 9 may be provided.

Furthermore, the nine-sided body is bent into a substantially U-shape, and the purpose of the bending is to form the bridge portion 13, arrange the cord-shaped heating element, and re-defrost the thin boxed frost. The shape to be bent may be approximately U-shape or V-shape without any problem.

Effects of the Invention The present invention has the following effects and has great industrial utility value.

(1) The contact area between the cord-shaped heating element, metal thin plate, and fins is larger than that of conventional products, and defrosting can be completed in a short time, so there is no deterioration of frozen foods.

Saves power.

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

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

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of an embodiment of the present invention, and FIG.
The figure is a perspective view of the heater unit used in this embodiment, and FIG. 3 is a partially cutaway sectional view showing the defrosting heating element of this embodiment attached to a heat exchanger. 1... Cord-shaped heating element, 5... Heat-fusible covering. 6...Metallic thin plate body, 7...Heat-sealed thin body.

Claims (1)

[Claims] A cord-shaped heating element (1) provided with a heat-sealable coating (5) on the outermost part is arranged in an appropriate shape on a heat-sealable thin body (7) provided on a metal thin plate-like body (6). In addition, the thin metal plate (6) is integrally formed around the outer periphery of the cord-shaped heating element (1), and is further bent with the thin metal plate (6) inside. A defrosting heating element characterized by being approximately U-shaped.