JPH051147U - Temperature fuse - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a thermal fuse that can be easily attached to various devices. [Structure] One end of a coil spring 1 that contracts in the length direction is joined to the other end of a circuit board 2, and the other end of the coil spring 1 is attached to the other end of the circuit board 2 via a low melting point metal 5. When the low melting point metal 5 is melted by heat, the coil spring 1 separates from the low melting point metal 5 and the circuit is cut off.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a thermal fuse. The present invention relates to components that prevent anomalies in electrical and electronic equipment, such as those that have a built-in charger or heater, malfunctions, malfunctions, and equipment that may cause heat generation due to abnormalities around the equipment.

[0002]

[Prior Art]

 As shown in FIG. 5, a conventional thermal fuse has a structure in which a low melting point metal 11 is enclosed in a ceramic case 10 and terminals 12 and 13 are provided at both ends. Therefore, this temperature fuse cannot be mounted on a circuit board together with other electronic components. This is because solder is usually used to attach components, and the low melting point alloy melts at the solder temperature.

Therefore, the thermal fuse must be installed elsewhere or at a distance from the circuit board. Therefore, it has a drawback that it requires a large space of equipment and cannot meet the recent demand for miniaturization.

[0004]

[Problems to be solved by the device]

 The present invention has been proposed in order to improve the above-mentioned drawbacks, and an object thereof is to provide a method of integrating a thermal fuse for preventing an abnormality of an electric / electronic device in advance with a circuit board and easily mounting it. ..

[0005]

[Means for Solving the Problems]

 According to the present invention, one end of a conductive coil is connected to a circuit board, and the other end of the coil spring is bonded to a low melting point metal provided on the circuit board. A thermal fuse characterized in that it has a restoring force in the opposite direction to the part where the metal is joined, and the low melting point metal melts in the abnormal state, the coil spring comes off from the low melting point alloy, and the circuit is cut off. It is characterized by.

[0006]

[Action]

 The thermal fuse of the present invention cuts off the circuit when an overcurrent flows or an exothermic ignition occurs due to an abnormality of equipment or parts by melting the low melting point metal and separating the coil spring from the connection terminal. Since it is provided on the circuit board, it has the function of being easily attached to equipment.

The present invention proposes a structure in which the thermal fuse can be easily attached to the circuit board. The material of the circuit board is not particularly limited, such as a laminated board and a ceramic board. On the circuit board, the thermal fuse of the present invention is mounted on the same circuit board as the normal parts of the equipment. The mounting method is shown below.

The spring used here is a coil spring 1 shown in FIG. 1A, a leaf spring 1a having a shape as shown in FIG. 1B, or the like that expands and contracts in parallel with the longitudinal direction. However, both ends should be planar to facilitate joining. The A end of the spring 1 is connected to the circuit board 2 via the wiring pattern 3 by a conventional joining method such as soldering 1.

FIG. 2 shows the attached state. The material of the coil spring has a high electric conductivity and a spring property, and the material is not particularly limited. Next, the B end of the coil spring 1 is attached to other parts of the circuit board 2 and then joined to the circuit board 2 with a low melting point metal 5 (alloy having a melting point of 50 to 300 ° C.). As a result, it was assembled as a thermal fuse.

FIG. 3 shows the assembled thermal fuse. In this thermal fuse, the low melting point metal melts due to overcurrent or temperature rise, and the circuit is cut off. Fig. 4 shows the external appearance of the interrupted thermal fuse.

[0011]

【Example】

 Next, examples of the present invention will be shown, but the present invention is not limited to the examples.

A low melting point metal having a phenolic paper laminated sheet made of spring steel and having an outer diameter of 3 mm, a length of 10 mm and a spring constant of 100 g / mm, one end connected with solder and the other end having a melting point of 97 ° C. It was fixed with (Sn-Pb-Bi alloy). This coil spring has a blocking direction, that is, a reaction force to the side opposite to the circuit board, and is fixed so as to block when the low melting point metal melts. An electric current was passed through the thermal fuse of this circuit board, a thermocouple was attached around the thermal fuse, and it was placed in an oven to gradually raise the temperature. The current flowing through the thermal fuse and the temperature at that time were measured, and the temperature at which the circuit was interrupted was determined. As a result, it was confirmed that the circuit was cut off within ± 1 ° C and that it was operating correctly as a thermal fuse.

[0013]

[Effect of the device]

 As described above, according to the present invention, a thermal fuse for electric and electronic equipment is integrated with a circuit board, and can be easily attached and can be accurately cut off.

[Brief description of drawings]

FIG. 1 shows the shape of a spring used in the present invention. (A) shows a coil spring and (b) shows a leaf spring.

FIG. 2 shows a shape in which a coil spring is attached to a circuit board.

FIG. 3 shows a state set as a thermal fuse.

FIG. 4 shows an interrupted thermal fuse.

FIG. 5 shows a conventional thermal fuse.

[Explanation of symbols]

 1 Coil spring 1a Leaf spring 2 Circuit board 3 Wiring pattern 4 Solder 5 Low melting point metal 10 Ceramics case 11 Low melting point metal 12, 13 Terminal

Claims (1)

Claims for utility model registration: 1. One end of a conductive coil is connected to a circuit board, and the other end of the coil spring is joined to a low melting point metal provided on the circuit board. Has a restoring force in the direction opposite to the part where the low-melting point metal is joined, and when abnormal, the low-melting point metal melts and the coil spring comes out of the low-melting point alloy, causing a circuit break. fuse.