JPS644313B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a heater, and particularly to the structure of a heater that is flexible, has a self-temperature control function, and is suitable as a defrosting heater for refrigerators, etc. .

In refrigerators, air conditioners, refrigeration cases, etc. equipped with a refrigeration system consisting of a compressor, condenser, capillary tube, and evaporator (hereinafter referred to as a cooler), frost that has adhered to the cooler is placed in the cooler. This prevents a decrease in the heat exchange rate of the cooler and a decrease in cooling capacity due to frost formation.

Conventionally, a defrosting heater is constructed by applying an insulation coating to a metal heater wire such as a nichrome wire or a nickel copper wire, and then housing the wire in a protective tube such as an aluminum pipe. This conventional defrosting heater is a constant power heater that maintains a constant amount of heat regardless of the ambient temperature or load condition, and the temperature of the load continues to rise with the energization time. Therefore, in order to detect the completion of defrosting, the temperature is detected using, for example, a thermistor temperature sensing element, and when the temperature detected by the sensing element reaches a certain temperature, heating by the defrosting heater is stopped and defrosting is finished. was. With this conventional defrosting heater, it is difficult to perform appropriate defrosting according to the amount of frost on the cooler and the distribution of frost. The cooler had to be heated to an excessive temperature. For this reason, in the cooler,
There is a disadvantage that areas where there is little frost and defrost is completed quickly become overheated, resulting in higher temperatures than necessary. In other words, during the defrosting period when the refrigeration system stops operating and the cooling function stops, the cooler becomes hotter than necessary, causing a temperature rise in the cooled items stored inside the refrigerator. . Therefore, there is a need for a defrosting heater that can defrost according to the frosting distribution and frosting state of each part of the cooler and does not cause overheating.

Figures 1a and 1b are perspective views and cross-sectional views showing the structure of a heater used in a defrosting heater;
In b, 1 is a flexible first power supply conductor, 1' is a flexible second power supply conductor arranged in parallel with the first power supply conductor 1, and 2 is a flexible first power supply conductor. A flexible resistor that is sandwiched between a first power supply conductor 1 and a second power supply conductor 1', has a positive temperature coefficient of resistance, and has a self-temperature control function that suddenly changes at a certain temperature. A material part (heating element part), 3 is an electrically insulating material part, and 4 is a pipe made of a metal material with good thermal conductivity. First, the operation of the flexible resistor material section (heat generating section) will be explained.

By applying a rated voltage between the first power supply conductor 1 and the second power supply conductor 1', it passes through the resistor material part 2 having a self-temperature control function, for example, the first
A current flows from the power supply conductor 1 to the second power supply conductor 1', and the resistor material portion 2 generates heat due to Joule heat. Resistor material part 2 due to temperature rise due to heat generation.
The organic material constituting the resistor material expands thermally, and the internal resistance of the resistor material portion 2 increases rapidly. Due to this increase in resistance value, the current flowing between the first power supply conductor 1 and the second power supply conductor 1' is regulated, and the resistor material part is heated to a certain temperature determined by the organic material constituting the resistor material part. The temperature of 2 increases.

After the resistor material part 2 having the above characteristics is covered with an electrically insulating material part 3, it is housed in a pipe 4 made of a metal material with good heat conduction, thereby forming a defrosting heater. This defrosting heater is used by being arranged in a corrugated manner in a cooler part of a refrigerator or the like. This heater can be regarded as having numerous resistor material parts having a self-temperature control function continuously arranged between the first and second power supply conductors 1 and 1'. The heater generates heat according to the amount of frost that has adhered, and the amount of heat generated by the heater in the part of the cooler that has been defrosted decreases, so that the temperature does not become unnecessarily high, making it a highly efficient defrosting heater. As described above, this defrosting heater has better defrosting performance than conventional defrosting heaters made of metal heater wires, but it still has problems in terms of heat transfer and assembly man-hours. That is, a step of inserting the resistor material section 2 provided with the electrically insulating material section 3 into a pipe 4 made of a metal material with good thermal conductivity is required, and this step requires an unexpected amount of time and effort. In order to facilitate the insertion process, it is necessary to provide a large difference between the inner diameter of the pipe 4 made of a metal material and the outermost dimension of the electrically insulating material portion 3.
However, in this case, there is a drawback that heat transfer between the resistor material part (heating element part) 2 and the pipe 4 made of a metal material is deteriorated. This drawback is that after the heater is inserted into the pipe 4 made of a metal material, the inner surface of the pipe 4 made of the metal material is brought into close contact with the insulating material part 3 of the heater by rolling the pipe 4 made of the metal material. Communication problems can be solved. However, in the rolling process, it is very difficult to process the resistor material part (heating element part) 2, which has a self-temperature control function, without applying pressure, and the state after rolling is (Heating element part) 2 is in a pressurized state, and the pressurizing pressure is not constant. The resistor material part (heating element part) 2 performs a self-temperature control function by rapidly increasing the internal resistance of the resistor material part 2 due to thermal expansion due to temperature rise of the organic material constituting the resistor material part 2. However, when the resistor material portion 2 is pressurized, a phenomenon occurs in which the specific resistance value increases, resulting in a drawback that a desired output cannot be obtained. That is, after inserting the resistor material part 2 designed to obtain a desired output into the pipe 4 made of metal material and performing rolling processing, the specific resistance value of the resistor material part 2 becomes the designed value. As the resistance value increases, variations occur in the resistance value, making it difficult to operate stably.

SUMMARY OF THE INVENTION An object of the present invention is to provide a defrosting heater that eliminates the drawbacks of the prior art described above, has excellent defrosting performance, and is easy to assemble.

In order to achieve the above object, the heater of the present invention includes at least a first flexible power supply conductor and a flexible second power supply conductor arranged in parallel with the first power supply conductor. and the first and second power supply conductors, the flexible conductor has a positive temperature coefficient of resistance, the temperature coefficient of resistance changes suddenly at a certain temperature, and has a self-temperature control function. A resistor material part, an electrically insulating material part provided on the outer periphery of the first and second power feeding conductors and the flexible resistor material part, and a thermally conductive material part provided on the outer periphery of the electrically insulating material part. A recess is formed in a part of the electrically insulating material part and the flexible resistance material part, and the recess is formed between the protective layer part and the electrically insulating material. Form a void.

The external structure and cross-sectional structure of the defrosting heater according to the present invention are shown in FIGS. 2a and 2b. In Figure 2, 1
is a flexible first wire such as tin-plated copper wire.
1' is a flexible second power feeding conductor arranged in parallel with the first power feeding conductor 1, 2 is the first power feeding conductor 1 and the second power feeding conductor. A flexible resistor material portion having a circular cross-section and having a self-temperature control function where the temperature coefficient of the resistance value is positive and the temperature coefficient of the resistance value changes suddenly at a certain temperature, which is placed between the conductors 1'. For example, it is formed from a conductive carbon material and a semiconductive organic material such as high-density polyethylene. 3 is the electrical insulation material section,
For example, it is made of polyurethane, polyvinylidene fluoride, etc., and 4 is a protective layer made of a material with good thermal conductivity that is in close contact with the electrically insulating material part 3, and is made of a metal material such as aluminum or copper. There is. 5 is a recess provided in a part of the flexible resistor material portion 2 having a circular cross-sectional shape; 6 is a gap formed between the recess of the electrically insulating material portion and the protective layer portion 4; be. In this defrosting heater, a flexible resistor material part 2 is integrally molded at least in the portion sandwiched between the first and second power supply conductors 1 and 1' by an extrusion molding method similar to the usual method of manufacturing electric wire materials. After that, the electrically insulating material portion 3 is formed by the same extrusion method as above, and then the electrically insulating material portion 3 is made of a material with good thermal conductivity, and the outer diameter of the electrically insulating material portion 3 is It is formed by inserting the protective layer part 4 made of aluminum material having a large inner diameter dimension, and then bringing the protective layer part 4 into close contact with the insulating material part 3 by means such as cold rolling. Resistor material portion 2 during and after formation of the protective layer portion 4
The pressure applied to the flexible resistor material part 2 is relaxed and absorbed by the recess 5 provided in a part of the electrically insulating material part 2 and the gap 6 formed between the recess 5 of the electrically insulating material part and the protective layer part 4, which solves the conventional problem. Warm flexible resistor material part 2
There is almost no increase in the specific resistance value. Next, the operation of the defrosting heater according to the present invention will be explained.

By applying a rated voltage between the first power supply conductor 1 and the second power supply conductor 1', it passes through the resistor material part 2 having a self-temperature control function, for example, the first
A current flows from the power supply conductor 1 to the second power supply conductor 1', and the resistor material portion 2 generates heat due to Joule heat. Resistor material part 2 due to temperature rise due to heat generation.
The organic material that makes up the material expands thermally. At this time, the resistor material part 2 thermally expands without being subjected to external pressure in the recess 5 of the resistor material part 2 and the gap 6 provided between the pipe 4 made of aluminum material and the electrically insulating material part 3, and resists the resistance. The internal resistance of the body material portion 2 increases rapidly. Due to this increase in resistance, the power supply conductor 1
and 1' is regulated, and the temperature rises to a constant temperature determined by the organic material forming the resistor material portion 2. As shown above,
By configuring the defrosting heater as shown in Figure 2, heat transfer from the heat generating part of the defrosting heater to the surface of the outermost protective layer is improved, and the outermost protective layer is provided in close contact with each other. It is possible to prevent characteristic fluctuations of the defrosting heater that would occur due to this, and it is possible to make the heater usable for practical use.

Next, another embodiment according to the present invention is shown in FIGS. 3 and 4. FIG. 3 shows a case where the flexible resistor material portion 2 is formed into an elliptical shape, with FIG. 3a showing a perspective view and FIG. 3b showing a cross-sectional view. The defrosting heater having the structure shown in FIG. 3 also gave good results similar to the defrosting heater having the structure shown in FIG. 2 shown above. Furthermore, the recess 5 provided in the flexible resistor material portion 2 is not limited to one location, but may be divided into several locations as shown in FIGS. 4a and 4b, and the same result as above can be obtained. Needless to say. Note that the recess 5 provided in the resistor material portion 2
The smaller is as small as possible without being affected by pressurization, the more desirable results will be obtained in terms of heat transfer.

As described above, according to the present invention, a flexible resistor material having a self-temperature control function is sandwiched between at least the first and second flexible power supply conductors arranged in parallel. By creating a structure in which a recess is provided in a part of the heater and a gap is provided between the heater and the outermost protective layer, thermal efficiency can be improved without impairing the characteristics of the flexible resistor material. It is possible to provide a defrosting heater that is good and capable of defrosting according to the frosting state.

[Brief explanation of drawings]

Figure 1 is a diagram showing the structure of the defrosting heater.
Figure a is a perspective view, Figure 1 b is a sectional view, Figures 2 and 3.
Figures 2 and 4 are diagrams showing the structure of an embodiment of the defrosting heater according to the present invention, and Figures 2a and 3a are perspective views, and Figures 2b, 3b, and 4
Figures a and b are cross-sectional views. DESCRIPTION OF SYMBOLS 1, 1'... Power supply conductor, 2... Flexible resistor material part, 3... Electrical insulating material part, 4... Protective layer part, 5... Recessed part.

Claims (1)

[Claims] 1 At least a flexible first power feeding conductor, a flexible second power feeding conductor arranged in parallel with the first feeding conductor, and the first and second feeding conductors. a flexible resistor material portion which is placed between the conductors for use, has a positive temperature coefficient of resistance value, and has a self-temperature control function in which the temperature coefficient of resistance value changes suddenly at a certain temperature; Consisting of a power supply conductor, an electrically insulating material part provided on the outer periphery of the flexible resistor material part, and a protective layer part made of a material with good thermal conductivity provided on the outer periphery of the electrically insulating material part. and a recessed portion forming a gap between the protective layer portion and the electrically insulating material portion is formed in a portion of the flexible resistor material and the electrically insulating material portion. heater.