JP3061620U - Thermistor for temperature detection - Google Patents

Abstract

(57) [Summary] [Problem] To provide a temperature detecting thermistor having a long life and high bending resistance. The temperature detecting thermistor includes a plurality of core wires (14) electrically connected to each of two lead wires of a negative characteristic thermistor element and an insulating coating (15) covering the periphery of the core wires. In the external wires, the diameter of the core wire (14) is 0.16 mm or less, and the number of the core wires is at least 15 or more. With such a configuration, there is an effect that the life is longer and the bending resistance is higher than that of a conventional temperature detecting thermistor having a similar resistance value.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a temperature detecting thermistor, and more particularly to a temperature detecting thermistor having an external wire having excellent bending resistance.

[0002]

[Prior art]

 In recent years, refrigerators and refrigerators for home use have generally been equipped with an automatic ice making device and a device for storing manufactured ice.

[0003] In those apparatuses, for example, a user transfers a predetermined amount of water put in a water storage container to an ice tray having an opening on an upper surface, and the temperature of the ice tray is measured by a temperature sensor attached to the ice tray. While monitoring the temperature, the water is frozen to freeze the water, and when the temperature reaches a predetermined temperature or when a certain time has elapsed after reaching the temperature, it is determined that the ice making is completed, and the ice making tray is rotated by 180 degrees to rotate the ice tray. It is performed by repeating the operation of dropping ice from the opening into the ice storage box provided under the ice tray. Ice is stored by cooling the ice storage box to a constant temperature.

In an ice tray of such an apparatus, it is common to use a negative characteristic (NTC) thermistor as a temperature sensor, attach it to the bottom of the ice tray, and draw out an external electric wire to monitor the temperature. . One example is shown in FIG. FIG. 1a is a side view of an ice tray having a temperature detecting thermistor attached to the bottom surface, and FIG. 1b is a bottom view thereof. These figures are schematic views showing the attachment of the thermistor, and other components are omitted.

As shown in FIGS. 1A and 1B, a temperature detecting thermistor 3 is adhered on an outer surface of a bottom portion 2 of an ice tray 1 with an adhesive resin 4. Then, two external electric wires 5a and 5b are drawn out from one side surface of the thermistor 3 and extend.

FIG. 2 schematically shows the internal configuration of the thermistor shown in FIG. As shown in FIG. 2, the thermistor 3 of FIG. 1 bends one lead wire 6b of a negative characteristic thermistor element 7 having two bendable lead wires 6a and 6b such as a radial lead wire. And the other end of each lead wire 6a, 6b is twisted with the core wire exposed at the end of the insulated outer wire 5a, 5b. After being press-bonded and electrically connected, the external electrodes 5a and 5b are drawn out. After being placed in a case 10 having an opening 9, a casting resin 11 such as an epoxy resin is injected into the case 10 through the opening 9. It is configured to be cured and integrated.

As the external electric wires, as schematically shown in FIG. 3, a small number (here, seven) of core wires 12 having a relatively large diameter of, for example, about 0.3 mm are bundled, and the entirety thereof is formed as a whole. The one covered with an insulating coating 13 made of resin is used. Conventionally, such external wires have been widely used because of their large cross-sectional area and low resistance.

[0008]

[Problems to be solved by the invention]

 However, as described above, in the temperature detecting thermistor attached to the ice tray provided in the ice making device of the freezer / refrigerator, since the operation of rotating the ice tray 180 degrees and then returning is repeated, the thermistor is used. The external electric wire drawn out from the terminal is exposed to strong bending and / or torsion, especially at the end of the thermistor case.

[0009] In an application exposed to such strong bending and / or torsion, the conventional thermistor uses an external electric wire having a thick core as shown in FIG. There has been a problem that the bending stress is large due to the large stretching stress, and the bent portion is deteriorated every time the bending is repeated, so that cutting due to brittle fracture occurs relatively early.

[0010] The present invention has been made in view of the above problems, and has as its object to provide a temperature detecting thermistor having an external electric wire that is more excellent in bending resistance than conventional ones.

[0011]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, a temperature detecting thermistor according to the present invention includes a case, a negative characteristic thermistor element having two leads arranged in the case, and an electric current connected to each of the two leads. A plurality of core wires which are electrically connected to each other and two external electric wires made of an insulating coating covering the periphery of the core wires, and a casting resin which fills a gap between each member in the case. The electric wire is a thermistor for temperature detection led out of the case, wherein the diameter of the core wire is 0.16 mm or less, and the number of the core wires is at least 15 or more. The temperature sensing thermistor of the present invention has such characteristics that it has a longer service life and higher bending resistance than the conventional one.

Preferably, in claim 1, the insulating coating has a thickness in a range of 0.3 to 0.5 mm. With such a configuration, a thermistor for temperature detection that is more excellent in bending resistance can be obtained.

[0013]

[Embodiment of the invention]

 One embodiment of the temperature detecting thermistor according to the present invention will be described below with reference to the drawings.

FIG. 4 is a cross-sectional view of a main part of the temperature detecting thermistor according to the present invention, that is, an external electric wire. In FIG. 4, the external electric wire of the present invention is obtained by bundling a larger number of core wires 14 having a diameter smaller than the conventional one (here, fifteen core wires having a diameter of 0.16 mm) and covering the whole with an insulating coating 15. It is configured. The material of the core wire 14 is not particularly limited as long as it is a conductive metal, but a copper wire can be suitably used from the viewpoint of cost, conductivity, and bending resistance. The other configuration of the temperature detecting thermistor according to the present invention may be the same as the conventional temperature detecting thermistor shown in FIGS. 1 and 2, for example, and is not particularly limited.

According to the present invention, it has been found that the use of a thick core wire having a low resistance value in a conventional external electric wire is a cause of impairing the bending resistance, and that the diameter of each core wire is large. That is, it is based on the knowledge that the magnitude of the sum of the cross-sectional areas of all the core wires, not the magnitude of the cross-sectional area of each core wire, determines the resistance value of the entire external electrode. In other words, by using a core wire having a small cross-sectional area, the expansion stress at the time of bending is suppressed to a small extent, and the occurrence of cutting due to brittle fracture is delayed. Therefore, a low resistance value is obtained. By the way, as far as the present inventor knows, it seems that there has not been any report that the technical idea has attempted to approach the cutting of the external electric wire.

Based on the above technical idea, the inventor conducted the following test in order to determine the conditions of the diameter and the number of core wires exhibiting appropriate characteristics as the external wires of the temperature detecting thermistor.

First, using core wires having various diameters shown in Table 1 below, a predetermined number of core wires are bundled so that the sum of the cross-sectional areas of the entire external electric wire is substantially the same, and six types of sample numbers 1 to 6 are obtained. And other types of insulated outer wires, and using them to manufacture a thermistor for temperature detection having the configuration shown in FIG. 2, attaching the manufactured thermistors to an ice tray as shown in FIG. It was a sample.

Next, the specimen is placed at a room temperature of 25 ° C., the external electric wire is fixed, and after energization of the external electric wire is started, the current flowing through the external electric wire while bending the ice tray left and right sequentially by 90 ° is set. The amount was measured. When the measured current amount became zero, it was considered that the external wire of the specimen was cut due to brittle fracture. At this time, one reciprocation bent 90 degrees each side was counted as one bending, and the bending speed was 30 times per minute under a load of 250 g. In such a test, a specimen having the number of bending times required for cutting, that is, the number of breaking times of 3,000 or more, was determined to be a good product.

Table 1 below shows test materials and test results.

[0020]

[Table 1] As can be seen from Table 1 above, Sample Nos. 1 and 2 did not meet the criteria for non-defective products with 3,000 breaks. On the other hand, Sample Nos. 3 to 6 all exceeded the non-defective criteria, and the better the results, the larger the number of core wires bundled into a thin core wire.

From the test results, it can be seen that as an external wire used for a temperature sensing thermistor used for mounting an ice tray as described above, a core wire is required if the cross-sectional area of the entire external wire is the same, for example, for applications requiring bending resistance. diameter is suitable as is often the number of bundled thin, for example if the ² order sum 0.096πmm of the cross-sectional area of the entire outer wires as shown in Table 1, 15 or more of the following core diameter 0.16mm Bundled external wires may be preferred.

The insulating coating covering the core wire of the external electric wire of the temperature detecting thermistor according to the present invention can be manufactured by a conventional method using an insulating material commonly used in the art, such as an insulating resin material. Further, the coating thickness (coating thickness) is not particularly limited, but is preferably about 0.3 to 0.5 mm from the viewpoint of easy bending.

Since the temperature detecting thermistor of the present invention employs such an external electric wire, the temperature detecting thermistor has excellent characteristics such as longer life and higher bending resistance than the conventional one.

[0024]

[Effect of the invention]

 As described in detail above, the temperature sensing thermistor according to the present invention has an external electric wire in which a larger number of core wires having a smaller diameter than the conventional one are bundled together, so that the expansion stress is smaller than that of the conventional external electric wire. As a result, the occurrence of brittle fracture is suppressed, the bending resistance is improved without impairing the resistance value characteristics, and a longer product life can be ensured than before.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conventional temperature detecting thermistor attached to an ice tray.

FIG. 2 is a diagram schematically showing an internal configuration of a conventional temperature detecting thermistor.

FIG. 3 is a sectional view of an external electric wire of a conventional temperature detecting thermistor.

FIG. 4 is a sectional view of an external electric wire of the temperature detecting thermistor of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ice tray 2 Bottom part 3 Temperature detecting thermistor 4 Adhesive resin 5a, 5b External electric wire 6a, 6b Lead wire 7 Negative characteristic thermistor element 8a, 8b Caulking 9 Opening 10 Case 11 Casting resin 12, 14 Core wire 13, 15 Insulation coating

Claims (2)

[Utility model registration claims] 1. A case, and a case arranged in the case.
A negative thermistor element having two lead wires;
Including a plurality of core wires electrically connected to each of the lead wires and two external electric wires made of an insulating coating covering the periphery of the core wires, and a casting resin filling a gap between each member in the case. A temperature sensing thermistor in which the two external wires are led out of the case, wherein the diameter of the core wire is 0.16 mm or less, and the number of the core wires is at least 15 or more. Thermistor for temperature detection. 2. The thermistor for temperature detection according to claim 1, wherein said insulating coating has a thickness in a range of 0.3 to 0.5 mm.