JPH0935603A - Thermal fuse with built-in resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal fuse with a built-in resistor, high accurately performing breaking action, by unifying a mutual distance interval, between a resistor and a thermal fuse, arranged in the recessed part of a case. SOLUTION: A pair of electrodes 8 are arranged in the bottom surface of the recessed part 5 of a case 4 with an upper opening, and a resistor 9, having a region opposite to a fusible body 11 forming a thermal fuse 3, is printedly formed between the electrodes 8. Moreover, since the lead wire 12 of the fuse 3 is positioned by the lead wire receiving part 7 of the case 4, the fitting positions, that is, the mutual distance and interval, of the fuse 3 and a resistor 2 arranged in a recessed part 5 of the case 4, can be unified. Consequently, when an excessive current flows in a circuit to heat the resistor 9, the heated temperature of it is correctly conducted to the fusible body 11 forming the fuse 3 to high accurately operate the breaking action of the temperature fuse.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance built-in type thermal fuse, and more particularly to a high-precision built-in resistance type thermal fuse in which a resistor is printed.

[0002]

2. Description of the Related Art Generally, when a current exceeding a specified value flows through a circuit, the resistors generally generate heat and the ambient temperature rises. An element that detects this rise in ambient temperature and shuts off the circuit is a thermal fuse and is used in various circuits. In the thermal fuse, when the temperature exceeds a specified temperature, the fusible material forming the thermal fuse melts and electrically cuts off the circuit. Further, as an element that accurately detects a temperature rise due to an abnormal current and shuts off the circuit, there is a combined resistance built-in type temperature fuse in which a temperature fuse and a resistor are combined.

FIG. 5 shows a schematic perspective view of a conventional thermal fuse with a built-in resistor, and FIG. 6 shows a perspective view before cemented and sealed with cement. As shown in the figure, the built-in resistor type thermal fuse 20 has a pair of slit-shaped lead receiving portions 22 provided in a case 21 having an upper opening, and a lead wire 24 a of a ready-made resistor 24 and a lead wire of a ready-made thermal fuse 25. Both ends of each 25a are arranged so as to crosslink each other. Next, as shown in FIG. 5, cement 26 is poured into the recess 23 of the case 21 to fix and seal it. If any abnormality occurs in the device to which the built-in resistance type thermal fuse manufactured in this manner is attached, an overcurrent flows in the circuit and the built-in resistance generates heat. This heat is detected by the thermal fuse, and when the temperature exceeds the rated temperature, the fusible body forming the thermal fuse is melted and electrically cuts off the circuit.

[0004]

However, in the resistance built-in type thermal fuse 20 as described above, the case 21 is used.
The mounting positions of the thermal fuses 25 arranged in the recesses 23 of the above-mentioned ones also vary, and similarly, the mounting positions of the resistors 21 also vary. That is, the distance between the thermal fuse 25 and the resistor 24 becomes a problem. This variation is caused by the thermal fuse 2.
5 when assembling the 5 and the resistor 21, and when cement 26 is poured into the recess 23 and fixed after assembly,
One of the causes is that the temperature fuse 25 and the resistor 21 swing. If there is variation in the distance between the two, even if overcurrent flows and the resistor 21 generates heat, uneven heating occurs around the temperature fuse 25. Therefore, case 2
The variation in the mounting position of the thermal fuse 25 and the resistor 21 in the concave portion 23 of No. 1 causes variation in the heat conduction and the thermal response between the thermal fuse 25 and the resistor 21. As a result will be impaired.

Therefore, the present invention has been proposed in view of the above problems, and an object thereof is to provide a means for eliminating the variation in the mounting positions of the temperature fuse and the resistor in the case, thereby improving the original temperature. It is an object to provide a thermal fuse with a built-in resistor that enables the function of the fuse to be performed with high accuracy.

[0006]

A resistor and a thermal fuse are sealed in a case having a slit-shaped lead wire receiving portion on both end walls at an upper surface opening, and a pair of lead wires of the resistor and the thermal fuse are connected to the lead wire receiving portion. A resistance built-in type thermal fuse further derived from which a resistor of the resistor is formed by printing.

Further, there is provided a thermal fuse having a built-in resistor, in which a fusible body of the thermal fuse faces a resistor forming a resistor and is arranged in parallel with a prescribed gap. Further, there is provided a resistance built-in type thermal fuse in which means for sealing the case and the lid is resin sealing. Further, there is provided a resistance built-in type thermal fuse in which one of each pair of lead wires is a square lead wire.

[0008]

According to the above construction, the pair of electrodes are arranged on the bottom surface of the concave portion of the case of the upper opening, and the resistor is printed and formed so as to have a region facing the fusible body forming the thermal fuse between the electrodes. Since the lead wire of the thermal fuse is positioned by the lead wire receiving portion of the case,
The mounting positions of the thermal fuse and the resistor arranged in the recess of the case, that is, the mutual distance intervals are made uniform. Therefore, when an overcurrent flows through the circuit and the resistor heats up, the heat generated temperature is accurately transmitted to the fusible body forming the temperature fuse, and the temperature fuse operates with high precision.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a resistance built-in type thermal fuse according to the present invention, FIG. 2 is a plan view seen from the upper surface before the lid of the resistance built-in type thermal fuse is fitted, and FIG. 3 is seen from the AA direction of FIG. FIG. 4 is a perspective view showing the shape of the case of the upper opening. In the figure, 1 is a thermal fuse with a built-in resistor, 2 is a resistor, 3 is a thermal fuse, 4 is a case, and 5
Is a concave portion of the case, 6 is a lead wire receiving portion A, 7 is a lead wire receiving portion B, 8 is a resistor electrode, 9 is a resistor, and 10 is a resistor 2.
The rectangular lead wires A and 11 are fusible bodies forming the thermal fuse 3, 12 is the round lead wires B and 13 of the thermal fuse 3, 13 is a lid, and 14 is a sealing resin.

As shown in FIG. 4, the case 4 having the concave portion 5 is, for example, a case made of ceramic, and a pair of slit-shaped lead receiving portions A6 and B are formed on the side face at the upper opening.
It consists of 7. As shown in FIGS. 2 to 4, the built-in resistor type thermal fuse 1 is roughly composed of a resistor 2 and a thermal fuse 3. The resistor 2 is formed with a pair of electrodes 8 in a recessed portion 5 of the case 4, that is, in a position that is continuous with the bottom surface 8a, the inner side surface 8b, and the lead wire receiving portion A6 and faces them. The pair of electrodes 8 is formed by screen printing, for example, silver or silver palladium. Next, a resistor 9 is formed by screen printing between the pair of electrodes 8 formed on the bottom surface 8a of the recess 5 and sintered. The lead wire A10 is soldered or adhered with a conductive paste as a lead-out lead to the lead wire receiving portion A6 on which the electrode 8 is formed. In this way, since the resistor 9 forming the resistor 2 is screen-printed, there is no variation in assembly.

On the other hand, the thermal fuse 3 has a fusible body 11 in advance.
The lead wire B12 is welded to both ends of the wire. Using the positioning jig, the lead wires B12 at both ends of the thermal fuse 3 are placed on the lead receiving portion B7 and fixed by the sealing resin 14. The lead wire B12 is exposed outside the case 4 as a lead-out lead. The fusible body 11 of the thermal fuse 3 is arranged on the resistor 9 and parallel to the resistor 9 so as to maintain a specified gap. As described above, since the thermal fuse 3 is mounted by using the positioning jig, the variation is reduced. Therefore, the mounting positions of the resistor 2 and the thermal fuse 3, that is, the mutual distance intervals are made uniform. Then, the peripheral edge of the upper surface of the case 4 and the lid 13 are sandwiched by the pair of lead wires A and B, respectively, to seal the resin 1.
4. Seal and seal with epoxy resin, for example. Therefore, it is not necessary to fill the recess 5 of the case 4 with cement or resin.

As in the above embodiment, the lead wire A10 of the resistor 2 is rectangular, and the lead wire B1 of the thermal fuse 3 is the same.
By making 2 round, it is possible to prevent wiring mistakes when connecting to a circuit.

[0013]

As described above, according to the resistance built-in type thermal fuse of the present invention, a pair of electrodes is arranged on the bottom surface of the recess of the case for coupling with the resistor 9, and the thermal fuse is provided between the electrodes. Since the resistor forming the resistor is printed so as to have a region facing the fusible body to be formed, and the temperature fuse is positioned by the lead wire receiving portion of the case, the resistor arranged in the recess of the case Mounting positions with the thermal fuse, that is, mutual distance intervals are made uniform. Therefore, when an overcurrent flows through the circuit and the resistor heats up, the temperature of the heat is accurately transmitted to the thermal fuse, and the thermal fuse operates with high accuracy. It is possible to provide a highly accurate thermal fuse with a built-in resistor that eliminates variations in heat conduction and thermal response between the thermal fuse and the resistor.

[Brief description of drawings]

FIG. 1 is a perspective view of a thermal fuse with a built-in resistor according to the present invention.

FIG. 2 is a plan view of the temperature fuse with built-in resistor shown in FIG.

FIG. 3 is a cross-sectional view seen from the direction AA of FIG.

FIG. 4 is a perspective view showing the shape of a case according to the present invention.

FIG. 5 is a schematic perspective view of a conventional thermal fuse with a built-in resistor.

FIG. 6 is a perspective view showing the state of the built-in resistance type thermal fuse of FIG. 5 before cementing.

[Explanation of symbols]

 1 Thermal fuse with built-in resistor 2 Resistor 3 Thermal fuse 4 Case 5 Recessed portion 6 Lead wire receiving portion A 7 Lead wire receiving portion B 8 Electrode 9 Resistor 10 Lead wire A 11 Fusible body 12 Lead wire B 13 Lid 14 Sealing resin

Claims (4)

[Claims] 1. A resistor and a temperature fuse are sealed in a case having a slit-shaped lead wire receiving portion on both end walls at an upper surface opening, and a pair of lead wires of the resistor and the temperature fuse are connected from the lead wire receiving portion. In the derived thermal fuse with built-in resistor, the resistive element of the resistor is formed by printing. 2. The thermal fuse with a built-in resistor according to claim 1, wherein the fusible body of the thermal fuse is arranged in parallel with the resistive body forming the resistor so as to face the resistive body with a prescribed gap. 3. The resistance built-in type thermal fuse according to claim 1, wherein the means for sealing the case and the lid is resin sealing. 4. The resistance built-in type thermal fuse according to claim 1, wherein one of the pair of lead wires is a square lead wire.