CN115020165A

CN115020165A - Thermal fuse

Info

Publication number: CN115020165A
Application number: CN202210619822.2A
Authority: CN
Inventors: 洪尧祥; 陈春水; 黄荣钦
Original assignee: Xiamen Set Electronics Co Ltd
Current assignee: Xiamen Set Electronics Co Ltd
Priority date: 2022-06-02
Filing date: 2022-06-02
Publication date: 2022-09-06

Abstract

The invention relates to a thermal fuse, which comprises a shell, fusible alloy, a fluxing agent and two leads, wherein the shell is made of a plastic material; one end of the lead is provided with an end socket, and the end socket is provided with a groove; two ends of the fusible alloy are respectively connected with the ends of the two leads; the fusing assistant agent is coated on the outer side of the fusible alloy; the fusible alloy, the fluxing agent and the end are all arranged in the shell. According to the technical scheme, the end is arranged at the contact position of the fusible alloy and the lead, the groove is formed in the end, and due to the fact that the capillary phenomenon exists in the groove, the fusible alloy has adsorption force on the fusible hardware when the fusible alloy is fused, so that the speed of fusing and shrinking the fusible alloy to the end is accelerated, and a part of the fusible alloy can be absorbed in the opening, and the breaking distance is increased. For the high-current thermal fuse, the ratio of the length to the diameter of the fusible alloy can be reduced, so that the overall length of the thermal fuse is reduced, and the fusing capability of a product is improved.

Description

Thermal fuse

Technical Field

The invention relates to the technical field of safety protection circuits, in particular to a fuse.

Background

A thermal fuse, also called a thermal fuse, is a temperature-sensitive circuit breaker. The temperature fuse can sense the overheating generated in the abnormal operation of the electric and electronic products, thereby cutting off the loop to avoid the fire. It is commonly used in electric appliances such as hair dryers, electric irons, electric cookers, electric furnaces, transformers, electric motors, drinking water dispensers, coffee makers and the like. The existing thermal fuse generally comprises a shell, a fusible alloy wire and two metal leads, wherein the fusible alloy wire is positioned in the shell, two ends of the fusible alloy wire are respectively connected and conducted with the two metal leads, a metal lead shaft penetrates out of the shell, and the side face of the fusible alloy wire is wrapped with an auxiliary fusing agent.

In the prior art, in order to meet the requirement that the fusible alloy can be quickly shrunk to the metal leads on two sides when fused, the size of the fusible alloy is generally at least 3 according to the length-to-diameter ratio: 1. In the existing temperature fuse, the effective coefficient of the absorption of the fusible alloy is generally 0.75, the relationship between the absorption surface Sd and the absorption height Hd of the fusible alloy at the metal pin connection part, the length L of the fusible alloy and the radius r of the fusible alloy is as follows: sd Hd 0.75 > Lpi r ² In order to increase the size of the fusible alloy absorbing surface, the size of the end surface of the pin contacting the fusible alloy is increased. In the application occasion of large current, the overall axial dimension of the temperature fuse is longer due to the length of the fusible alloy and the requirement of the absorption space. Such an elongated structure makes it impossible to use such a thermal fuse in applications where axial installation space is required.

Disclosure of Invention

Therefore, it is necessary to provide a fuse for solving the problems of too long current temperature fuse and inconvenient installation and use.

A thermal fuse comprises a shell, a fusible alloy, a fluxing agent and two leads; one end of the lead is provided with an end head, and a groove is formed in the end head; two ends of the fusible alloy are respectively connected with the ends of the two leads; the fusing assistant agent is wrapped on the outer side of the fusible alloy; the fusible alloy, the fluxing agent and the end are all arranged in the shell.

Further, the end head is of a boss structure with a cross section larger than that of the lead at other positions; the groove is formed by inwards sinking from the side wall of the end head.

Furthermore, the groove is in a V-shaped groove, a U-shaped groove or an inverted trapezoidal groove, and the end face of the end is welded with the fusible metal; the inner side wall of the groove and the side wall of the end head form an included angle of 30-90 degrees.

Furthermore, the groove is a recess which is recessed from the end face of the end head along the axial direction.

Furthermore, the end head and the lead are integrally formed, the size of the cross section of the end head is the same as that of other positions of the lead, and the end face of the end head is welded with the fusible alloy.

Further, a ratio of an axial length of the fusible alloy to a diameter length of the fusible alloy is less than or equal to 2.

Furthermore, the number of the grooves is multiple, and the grooves are uniformly distributed on the end head at equal intervals.

Furthermore, a wrapping shell is arranged between the fusing assistant agent and the shell.

Further, the wrapping shell comprises a first shell and a second shell which are provided with buckles; the first shell and the second shell are buckled with each other to form an accommodating cavity, the fusible alloy, the fluxing agent and the end are arranged in the accommodating cavity, and the lead is led out from the accommodating cavity and the shell; wherein, the shell is integrally formed by injection molding of a thermosetting material.

According to the technical scheme, the end is arranged at the contact position of the fusible alloy and the lead, the groove is formed in the end, and due to the fact that the capillary phenomenon exists in the groove, the fusible alloy has adsorption force on the fusible hardware when the fusible alloy is fused, so that the speed of fusing and shrinking the fusible alloy to the end is accelerated, and a part of the fusible alloy can be absorbed in the opening, and the breaking distance is increased. For the high-current thermal fuse, the ratio of the length to the diameter of the fusible alloy can be reduced, so that the overall length of the thermal fuse is reduced, and the fusing capability of a product is improved.

Drawings

FIG. 1 is a disassembled schematic view of a first embodiment of a thermal fuse in accordance with the present invention;

FIG. 2 is a schematic transverse cross-sectional view of a first embodiment of a thermal fuse of the present invention;

FIG. 3 is a schematic longitudinal cross-sectional view of a first embodiment of a thermal fuse of the present invention;

FIG. 4 is a schematic diagram of various terminal ends of the thermal fuse of the present invention;

FIG. 5 is an exploded view of one embodiment of a thermal fuse of the present invention;

FIG. 6 is a schematic structural view of a lead and fusible alloy of a second embodiment of the thermal fuse of the present invention;

fig. 7 is a schematic view of a second embodiment of a thermal fuse according to the present invention.

In the drawings, the components represented by the respective reference numerals are listed below:

1. a housing; 2. a fusible alloy; 3. a fusing assistant agent; 4. a lead wire; 5. a tip; 51. a groove; 6. wrapping the shell; 61. a first housing; 62. a second housing.

Detailed Description

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. It is understood that the specific details described below are merely exemplary of some embodiments of the invention, and that the invention may be practiced in many other embodiments than as described herein. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without any inventive step, are within the scope of the present invention.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not represent the only embodiments.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

In a first embodiment of the present invention, referring to fig. 1, fig. 2, fig. 3 and fig. 5, a thermal fuse includes a case 1, a fusible alloy 2, a fusing assistant 3 and two leads 4; one end of the lead 4 is provided with an end head 5, and the end head 5 is provided with a groove 51; two ends of the fusible alloy 2 are respectively connected with the end heads 5 of the two lead wires 4; the fusing assistant agent 3 is wrapped on the outer side of the fusible alloy 2; the fusible alloy 2, the fusing assistant 3 and the end 5 are all arranged in the shell 1.

According to the technical scheme, the end 5 is arranged at the contact position of the fusible alloy 2 and the lead 4, the groove 51 is formed in the end 5, the contact surface of the fusible alloy 2 is increased, and the absorption area of the fusible alloy 2 is increased; and the opening at the edge of the end part has a capillary phenomenon, so that the fusible alloy 2 has adsorption force to the fusible alloy 2 when being fused, the speed of fusing and shrinking the fusible alloy 2 to the end head 5 is accelerated, and the opening part can absorb a part of the fusible alloy 2, so that the disconnection distance is increased. For the high-current thermal fuse, the ratio of the length to the diameter of the fusible alloy 2 can be reduced, so that the overall length of the thermal fuse is reduced, and the fusing capability of a product is improved.

In the embodiment of the invention, the fusible alloy 2 is cylindrical and is a low-melting-point alloy, the fusing temperature is generally lower than 232 ℃, and the fusible alloy 2 commonly used in the existing thermal fuse is adopted. The fusing assistant 3 is mainly composed of rosin and is also made of materials commonly used in the existing thermal fuse. Of course, the shape may be an oval, a square, or a rectangle, and is not limited to the description in the embodiment.

On the basis of the implementation, the end 5 is of a boss structure with a cross section larger than that of the lead 4 at other positions; the groove 51 is formed by recessing inward from the side wall of the tip 5. It can be understood that the boss structure can improve the axial tension and play a role in limiting; and under the condition of the same size of the electrode lead 4, the absorption area is increased, and the setting of the groove 51 accelerates the occurrence of the capillary effect; the raised boss structure may form a boundary to control the amount of fusing aid 3.

Referring to fig. 4, wherein the groove 51 extends inwardly from the end edge, the groove 51 may be in the form of a V-shaped groove, a U-shaped groove or an inverted trapezoidal groove, and the end face of the tip 5 is welded to the fusible metal; the included angle between the inner side wall of the groove 51 and the side wall of the end head 5 is 30 to 90 degrees. With such a structure, the melted fusible alloy 2 is more quickly absorbed into the groove 51 due to the capillary effect. Of course, the shape of the groove 51 may be other, which is not limited to the description in the embodiment.

In a second embodiment of the present invention, as shown in fig. 6 and 7, the groove 51 is a recess recessed from the end surface of the tip 5 in the axial direction. Further, the end 5 and the lead 4 are integrally formed, the cross section of the end 5 is the same as that of the lead 4 at other positions, a boss structure is omitted, and the end face of the end 5 is welded with the fusible alloy 2.

In the technical scheme of the invention, the ratio of the axial length of the fusible alloy 2 to the diameter length of the fusible alloy 2 is less than or equal to 2. Preferably, the ratio of the length to the diameter of the fusible alloy 2 thereof may be 1: 1. the length of the thermal fuse is shortened through the structure, and meanwhile, the thermal fuse can be adapted to large current for use, so that the product is more compact and convenient to install.

In order to increase the contraction speed of the fused fusible alloy 2 during fusion, the number of the grooves 51 is plural, and the grooves 51 are uniformly distributed on the tip 5 at equal intervals.

For the above two embodiments, further, a wrapping shell 6 is provided between the fusing assistant 3 and the housing 1. Further, the wrapping case 6 includes a first case 61 and a second case 62 provided with a snap; first casing 61 forms one after the mutual buckle with second casing 62 and holds the chamber, and fusible alloy 2, help fusing agent 3 and end 5 all set up in holding the intracavity, and lead wire 4 draws in holding chamber and shell 1. The housing 1 is integrally injection molded from a thermosetting material.

Because the shell 1 is integrally formed by injection molding, the mold temperature needs to reach more than 170 ℃ during injection molding, and the fusing agent 3 can be softened and flow at the high temperature of 170 ℃, so that the wrapping shell 6 is arranged, the wrapping shell 6 can adopt a mode of buckling the first shell 61 and the second shell 62, and also can adopt a mode of arranging ultrasonic welding ribs on the first shell 61 and the second shell 62 for ultrasonic welding. The method of using a coating resin may also be used. The connection manner is not described as a limitation in the present embodiment.

The shell 1 may be made of thermosetting material, and phenolic resin is generally used. Of course, it may be made of other materials, which are not limited to the description in this embodiment.

In the embodiment using the snap, the snap may be provided on the first housing 61 and the second housing 62 and elastically deformed and restored to be locked. Of course, it may be in other ways, which are not described as limiting in this embodiment.

In the embodiment, in order to ensure that the plating layer of the pin lead 4 does not peel off in the high-temperature process of injection molding, the lead 4 can be processed by nickel plating.

In an embodiment, the fusible alloy 2 can also be made into a plurality of sheet structures which are not in contact with each other, the sheet structures are connected between the two end heads 5 in parallel, and the auxiliary fusing agent 3 is filled in gaps between different fusible alloys 2, so that the contact area between the auxiliary fusing agent 3 and the fusible alloy 2 is increased, and the fusing shrinkage speed of the fusible alloy 2 is further accelerated.

According to the technical scheme, the end 5 is provided with the groove 51, so that the contact surface with the fusible alloy 2 is increased, the absorption area of the fusible alloy 2 is increased, and the groove 51 at the edge of the end 5 has a capillary phenomenon, so that when the fusible alloy 2 is fused, the fusible alloy 2 has an adsorption force, the fusing shrinkage speed of the fusible alloy 2 is accelerated, and a part of the fusible alloy 2 can be absorbed in the groove 51, the breaking distance is increased, and the breaking capacity of a product is improved.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above examples only show several embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that various changes, substitutions and alterations can be made by those skilled in the art without departing from the spirit of the invention, and these are all intended to be covered by the scope of the invention. Therefore, the protection scope of the present invention should be subject to the claims.

Claims

1. A thermal fuse, comprising: the fuse comprises a shell, fusible alloy, a fluxing agent and two leads; one end of the lead is provided with an end socket, and a groove is formed in the end socket; two ends of the fusible alloy are respectively connected with the ends of the two leads; the fusing assistant agent is wrapped on the outer side of the fusible alloy; the fusible alloy, the fluxing agent and the end head are all arranged in the shell.

2. The thermal fuse according to claim 1, wherein said tip is a boss structure having a cross-section larger than other locations of said lead; the groove is formed by inwards recessing the side wall of the end head.

3. The thermal fuse according to claim 2, wherein said recess is in the shape of a V-shaped groove, a U-shaped groove or an inverted trapezoidal groove, and the end face of said tip is welded to said fusible metal; the inner side wall of the groove and the side wall of the end head form an included angle of 30-90 degrees.

4. The thermal fuse according to claim 1, wherein the groove is a recess recessed from an end face of the tip in an axial direction.

5. The thermal fuse according to claim 4, wherein said tip is integrally formed with said lead wire, and wherein said tip has a cross-section of the same size as the other portions of said lead wire, and wherein said tip has an end surface welded to said fusible alloy.

6. The thermal fuse according to claim 1, wherein a ratio of an axial length of the fusible alloy to a diameter length of the fusible alloy is less than or equal to 2.

7. The thermal fuse according to claim 1, wherein the number of the grooves is plural, and the grooves are uniformly distributed on the terminal at equal intervals.

8. A thermal fuse according to any one of claims 1 to 7, characterised in that a wrapping sheath is provided between the fuse aid and the outer sheath.

9. The thermal fuse according to claim 8, wherein the pack case includes a first case and a second case provided with a snap; the first shell and the second shell are buckled with each other to form a containing cavity, the fusible alloy, the fluxing agent and the end are arranged in the containing cavity, and the lead is led out from the containing cavity and the shell.

10. The thermal fuse according to claim 8, wherein the pack case includes a first case and a second case; the first shell and the second shell are welded through ultrasonic waves to form an accommodating cavity, the fusible alloy, the fluxing agent and the end are arranged in the accommodating cavity, and the lead is led out from the accommodating cavity and the shell; wherein, the shell is integrally formed by injection molding of a thermosetting material.