JP2023542373A - Thermal fuse - Google Patents

Abstract

This application relates to the field of protection devices, and in particular to thermal fuses, by changing the mode in which the push rod and the temperature sensing element are brought into direct contact to achieve transmission, and by adding a spring mechanism to both, the push rod and the temperature sensing element are indirectly connected. Achieve power transmission. Specifically, the spring mechanism includes a spring and a spring pin, the spring is sheathed on one end of the spring pin, the spring is in a compressed state when the thermal fuse is not triggered, and the temperature sensor is sheathed on the other end of the spring pin. One end of the push rod contacts the lead, the other end of the push rod contacts the end of one side wall of the spring pin, and the length of the temperature sensing element in the direction of expansion and contraction of the spring is the same as that of the spring pin in the direction of expansion and contraction of the spring. When the temperature sensitive element is triggered, the compressive elasticity of the spring is released and separates the other end of the push rod from the spring pin, and the lead also connects to the contact point due to the action of its own elasticity. Isolate and break the circuit. The above structure overcomes the problem of poor electrode contact due to deterioration of the temperature sensitive body. [Selection diagram] Figure 6

Description

TECHNICAL FIELD This application relates to the field of protection devices, and more particularly to thermal fuses.

This application claims priority to a Chinese patent application filed with the Chinese Patent Office on August 18, 2021, with application number 202122003888.2 and titled "Thermal Fuse", the entire content of which is incorporated herein by reference. is incorporated into.

A thermal fuse is an overheat protection element, and when the electronic device to be protected generates heat due to a malfunction or failure, and the temperature reaches the melting temperature of the thermal fuse, the fuse blows, thereby interrupting the circuit. A thermal fuse is composed of a temperature sensor, an electrode, a ceramic case, a push rod, a spring, and the like. Normally, this type of product has a temperature-sensitive body that is easily melted at the bottom, and a push rod is placed above it to push the lead. During operation, the temperature-sensitive body that is easy to melt melts, and the push rod A structure is used in which the support is removed, the contact between the lead and the electrode is broken, and the circuit is cut off. However, this structure causes the pressure between the lead and the electrode contact to increase as the temperature sensitive element, which is prone to melting, deteriorates and shrinks. It has the disadvantage that it changes and causes problems of poor contact.

The technical problem to be solved by the present application is to provide a thermal fuse that can effectively solve the problem of poor contact caused by pressure changes at electrode contacts caused by deterioration of a temperature sensitive element.

In order to solve the above technical problem, the technical solutions of the present application are as follows.

The thermal fuse includes leads and contacts arranged opposite to each other, and further includes a spring mechanism, a temperature sensing element, and a push rod, the spring mechanism includes a spring and a spring pin, and the spring is sheathed to one end of the spring pin. , when the thermal fuse is not triggered, the spring is in a compressed state, the temperature sensitive element abuts the other end of the spring pin, one end of the push rod abuts a lead, and the other end of the push rod is in a compressed state. The length of the temperature sensing element that abuts the end of one side wall of the spring pin in the direction of expansion and contraction of the spring is longer than the length of the push rod that abuts the spring pin in the direction of expansion and contraction of the spring.

Furthermore, the spring pin includes a base, two pin bodies provided on the same side of both ends of the base, and a connection part provided on the base, and the connection part and the pin body are provided on different sides of the base. The spring is mounted on the pin body, the temperature sensing element abuts on the connection part, and the other end of the push rod abuts on a portion of the base located between the two pin bodies.

Furthermore, the thermal fuse further includes a shell, and one end of the shell is provided with two electrode sheets spaced apart from each other, and each of the two electrode sheets corresponds one-to-one to a lead and a contact point. electrically connected.

Furthermore, a guide plate is provided inside the shell, and the guide plate is provided corresponding to the position of the push rod.

Furthermore, a copper cap is provided inside the shell, and the temperature sensing element is provided within the copper cap.

Furthermore, the connecting portion has a cylindrical shape, the inner space of the copper cap has a cylindrical shape, the temperature sensing element has a cylindrical shape, and the outer diameter of the connecting portion is equal to the outer diameter of the temperature sensing element, The inner diameter of the copper cap is larger than the outer diameter of the connection part.

Furthermore, the shell further includes a mounting plate having an opening at the other end of the shell, the mounting plate being fixed to the opening of the shell with a rivet to seal the opening, and the copper cap It abuts against the inner wall of the mounting plate.

Furthermore, a cavity is provided in the shell, an insulating mica sheet and a resistance wire are provided in the cavity, the resistance wire is electrically connected to a welding pin provided in the electrode sheet, and the insulating mica sheet is Provided between the resistance wire and the mounting plate.

Furthermore, the material of the shell is ceramic or plastic.

Furthermore, the material of the push rod is ceramic or plastic.

As a beneficial effect of the present application,
The thermal fuse according to the present application changes the mode in which the push rod and the temperature sensing element are brought into direct contact to achieve transmission, and by adding a spring mechanism between the two, indirect transmission between the push rod and the temperature sensing element is realized. , specifically, the spring mechanism includes a spring and a spring pin, the spring is sheathed on one end of the spring pin, the spring is in a compressed state when the thermal fuse is not triggered, and the temperature sensor is in contact with the other end of the spring pin, one end of the push rod is in contact with a lead, the other end of the push rod is in contact with an end of one side wall of the spring pin, and the length of the temperature sensing element in the direction of expansion and contraction of the spring is The length is greater than or equal to the length of the push rod that abuts the spring pin in the direction of expansion and contraction of the spring, and when the temperature sensor is triggered, the compressive elasticity of the spring is released to separate the other end of the push rod and the spring pin, and The lead separates from the contact due to its own elasticity, breaking the circuit. The above structure overcomes the problem of poor electrode contact due to deterioration of the temperature sensitive body.

FIG. 2 is a schematic structural diagram of a thermal fuse according to an embodiment of the present application. It is the arrangement|positioning form of the push rod of the thermal fuse based on the Example of this application. It is an arrangement|positioning form of the push rod of another thermal fuse based on the Example of this application. 1 is a structural exploded view of a thermal fuse according to Example 1 of the present application. FIG. FIG. 3 is another structural exploded view of the thermal fuse according to Example 1 of the present application. It is a structural exploded view of the thermal fuse of Example 2 of this application. FIG. 2 is an assembled sectional view of a thermal fuse according to Example 2 of the present application. FIG. 2 is a partial structural schematic diagram of a thermal fuse according to Example 2 of the present application. FIG. 3 is a partial front view of a thermal fuse according to Example 2 of the present application. It is a structural exploded view of the thermal fuse of Example 3 of this application. FIG. 7 is an assembled sectional view of a thermal fuse according to Example 3 of the present application.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to explain in detail the technical content, achieved objectives, and effects of the present application, description will be made below with reference to embodiments and drawings.

Referring to FIG. 1, FIG. 1 is a schematic structural diagram of a thermal fuse according to the present application, which includes an electrode sheet, a push rod spring, a push rod, and a spring mechanism, and the spring of the push rod spring is externally mounted on the push rod.

As shown in FIGS. 2 and 3, FIGS. 2 and 3 respectively show the design forms of the push rod of the thermal fuse according to the present application, and in FIG. 2, the guide pin has a protrusion and the bridge is fixed to form the push rod. It is shown in FIG. 3 that the holder is welded to the guide pin, a floating spring is placed inside the holder, and the bridge is fixed to form a push rod.

Referring to FIGS. 4 and 5, which is a first embodiment of the present application, FIGS. 4 and 5 are exploded structural views of the first embodiment of the present application, respectively. The thermal fuse of the present invention has two electrode sheets, each crimped to a ceramic case, the leads and contacts are spot welded to the two electrode sheets, respectively, the guide pin 17 and the holder 16 are integrally welded, and the holder 16, the floating spring 18 biases the bridge 19 so that it has a floating pressure when it contacts the contact 2, and the guide pin 17, the holder 16, the floating spring 18 and the bridge 19 are integrated. A push rod is formed, and a push rod spring 20 is disposed at the front end of the push rod. When the thermal fuse is not triggered, the push rod spring 20 is in a compressed state, and the resistance wire (regarding the effect), when the product is used in a circuit with a large rated current, the resistance wire exerts an arc-extinguishing effect, and the lead is removed from the contact point. (to prevent arcing when separated) is connected to a welding pin welded to the electrode sheet, the spring is placed inside the cavity of the ceramic case, the temperature sensor is placed inside the copper cap, and the upper end is connected to the spring pin. , the lower end of the pin body of the spring pin and the copper cap form a large clearance fit, the large gap is favorable for the melting and evacuation of the temperature sensor, and the upper end of the spring pin supports the two springs and attaches By being crimped to the ceramic case, the plate has the effect of transmitting temperature and fixing it, and the cover plate has a dust-proofing and sealing effect due to the gap between the rivet and the ceramic case.

As shown in FIGS. 6 to 9, the thermal fuse according to the present application includes leads and contacts arranged opposite to each other, and further includes a spring mechanism, a temperature sensing element, and a push rod, the spring mechanism includes a spring and a spring pin, The spring is sheathed on one end of the spring pin. When the thermal fuse is not triggered, the spring is in a compressed state, the temperature sensitive element abuts the other end of the spring pin, one end of the push rod abuts a lead, and the other end of the push rod is in contact with the spring pin. The length of the temperature sensing element that abuts the end of one side wall of the pin in the direction of expansion and contraction of the spring is longer than the length of the push rod that abuts the spring pin in the direction of expansion and contraction of the spring.

As can be seen from the above explanation, the beneficial effects of the present application include:
The thermal fuse according to the present application changes the mode in which the push rod and the temperature sensing element are brought into direct contact to achieve transmission, and by adding a spring mechanism between the two, indirect transmission between the push rod and the temperature sensing element is realized. . Specifically, the spring mechanism includes a spring and a spring pin, the spring is sheathed on one end of the spring pin, the spring is in a compressed state when the thermal fuse is not triggered, and the temperature sensor is in a compressed state. one end of the push rod abuts the lead, the other end of the push rod abuts the end of one side wall of the spring pin, and the length of the temperature sensing element in the direction of expansion and contraction of the spring; is greater than or equal to the length of the push rod that contacts the spring pin in the direction of expansion and contraction of the spring, and when the temperature sensor is triggered, the compressive elasticity of the spring is released, separating the other end of the push rod and the spring pin, and further leading Due to its own elasticity, it separates from the contact and breaks the circuit. The above structure overcomes the problem of poor electrode contact due to deterioration of the temperature sensitive body.

Furthermore, the spring pin includes a base, two pin bodies provided on the same side of both ends of the base, and a connection part provided on the base, and the connection part and the pin body are provided on different sides of the base. The spring is mounted on the pin body, the temperature sensing element abuts on the connection part, and the other end of the push rod abuts on a portion of the base located between the two pin bodies.

As can be seen from the above description, the above structure realizes indirect transmission between the temperature sensing body and the push rod.

Furthermore, the thermal fuse further includes a shell, and one end of the shell is provided with two electrode sheets spaced apart from each other, and each of the two electrode sheets corresponds one-to-one to a lead and a contact point. electrically connected.

Furthermore, a guide plate is provided inside the shell, and the guide plate is provided corresponding to the position of the push rod.

As can be seen from the above description, with the above structure, the guide plate is crimped and fixed within the shell, and is provided corresponding to the position of the push rod, thereby preventing the push rod from falling off.

Furthermore, a copper cap is provided inside the shell, and the temperature sensing element is provided within the copper cap.

As can be seen from the above description, the temperature sensitive body is limited by the above structure.

Furthermore, the connecting portion has a cylindrical shape, the inner space of the copper cap has a cylindrical shape, the temperature sensing element has a cylindrical shape, and the outer diameter of the connecting portion is equal to the outer diameter of the temperature sensing element, The inner diameter of the copper cap is larger than the outer diameter of the connection part.

As can be seen from the above description, the above structure creates a large clearance fit between the spring pin connection and the copper cap, and the large clearance is advantageous for melting and evacuation of the temperature sensor.

Furthermore, the shell further includes a mounting plate having an opening at the other end of the shell, the mounting plate being fixed to the opening of the shell with a rivet to seal the opening, and the mounting plate sealing the opening of the shell. A copper cap abuts the inner wall of the mounting plate.

As can be seen from the above description, with the above structure, the mounting plate is crimped to the shell by rivets, thereby providing a sealing effect and also a copper cap restriction effect. Further, conventional thermal fuses are sealed with a material such as resin, and if the temperature is too high, the sealing material melts, so they cannot be applied to high-temperature environments. On the other hand, according to the sealing method having the above structure, a thermal fuse having high temperature resistance and a high melting point can be realized.

Furthermore, a cavity is provided in the shell, an insulating mica sheet and a resistance wire are provided in the cavity, the resistance wire is electrically connected to a welding pin provided in the electrode sheet, and the insulating mica sheet is Provided between the resistance wire and the mounting plate.

As can be seen from the above description, with the above structure, when the product is used in a circuit with a large rated current, the resistance wire exerts an arc extinguishing effect and prevents arcing from occurring when the lead is separated from the contact.

Furthermore, the material of the shell is ceramic or plastic.

Furthermore, the material of the push rod is ceramic or plastic.

As can be seen from the above description, with the above structure, the temperature resistance can reach 500° C. or more.

Embodiment 2 of the present application is shown in FIGS. 6 to 9.
The thermal fuse according to the present application includes a lead 1, a contact 2, a spring mechanism, a temperature sensing element 3, a push rod 4, a shell 5, a guide plate 6, an electrode sheet 7, a mica sheet 8, a copper cap 9, a mounting plate 10, and a rivet 11. In this embodiment, the material of the shell is ceramic or plastic. The material of the push rod is ceramic or plastic.

Both opposing ends of the shell 5 are openings, specifically an upper end opening and a lower end opening.
The lead 1, the contact 2, the spring mechanism, the temperature sensing element 3, the push rod 4, the guide plate 6, and the copper cap 9 are all provided inside the shell 5, and the two electrode sheets 7 are spaced apart from each other with an opening at the upper end. A mica sheet 8 is also provided at the upper end opening and located between the two electrode sheets, and the two electrode sheets function as two connection terminals of the product. In this embodiment, the mica sheet can be inserted into the gap between the electrode sheet and the shell from the side, and exhibits a dust-proofing and sealing effect.

The leads 1 and contacts 2 are provided facing each other, and the two electrode sheets are electrically connected to the leads and contacts in one-to-one correspondence, respectively,
The spring mechanism includes a spring 12 and a spring pin 13, and the spring pin 13 has a base 131, two pin bodies 132 provided on the same side of both ends of the base 131, and a connecting portion 133 provided on the base 131. , the connecting part 133 and the pin body 132 are on different sides of the base, the spring 12 is sheathed on the pin body 132, the spring 12 is sheathed on one end of the spring pin 13, and the thermal fuse is triggered. When not in use, the spring is in a compressed state, the temperature sensing element 3 is in contact with the other end of the spring pin 13, one end of the push rod 4 is in contact with the lead 1, and the other end of the push rod 4 is in contact with the spring pin 13. The length of the temperature sensing element 3 in the direction of expansion and contraction of the spring, which is in contact with the end of one side wall, corresponds to the length of the push rod 4 in the direction of expansion and contraction of the spring. The temperature sensing element 3 contacts the connecting portion 133, and the other end of the push rod 4 contacts a portion of the base located between the two pin bodies.

A guide plate 6 is provided inside the shell 5, and the guide plate is provided corresponding to the position of the push rod. The guide plate is fixed in the shell with rivets and is provided corresponding to the position of the push rod, thereby preventing the push rod from falling off.

A copper cap 9 is provided inside the shell 5, the temperature sensing element 3 is provided in the copper cap 9, the connecting portion 133 has a cylindrical shape, and the internal space of the copper cap 9 has a cylindrical shape. , the temperature sensing element 3 has a cylindrical shape, the outer diameter of the connecting part is equal to the outer diameter of the temperature sensing element, and the inner diameter of the copper cap is larger than the outer diameter of the connecting part. A large clearance fit is formed between the spring pin connection and the copper cap, and the large clearance is advantageous for melting and evacuation of the temperature sensor.

The mounting plate 10 is fixed to the lower end opening of the shell by rivets 11 to seal the lower end opening, and the copper cap 9 abuts the inner wall of the mounting plate 10.

Preferably, the shell is a ceramic shell, and the temperature sensor uses a material with a trigger mechanism higher than 300°C. Furthermore, the thermal fuse can be applied to temperatures of 300° C. or higher.

Embodiment 3 of the present application is shown in FIGS. 6 to 11.
The difference from the second embodiment is that a resistance wire is added inside the shell. Specifically, a cavity is provided in the shell, an insulating mica sheet 15 and a resistance wire 14 are provided in the cavity, and the resistance wire 14 is electrically connected to a welding pin provided in the electrode sheet 7. The insulating mica sheet 15 is provided between the resistance wire 14 and the mounting plate 10. With the above structure, when the product is used in a circuit with a large rated current, the resistance wire exhibits an arc-extinguishing effect and prevents arcing when the lead is separated from the contact.

As described above, the thermal fuse according to the present application changes the mode in which the push rod and the temperature sensing element are brought into direct contact to achieve transmission, and by adding a spring mechanism between the two, the push rod and the temperature sensing element are connected. indirect transmission is achieved, specifically, the spring mechanism comprises a spring and a spring pin, the spring is sheathed on one end of the spring pin, and the spring is in a compressed state when the thermal fuse is not triggered. , the temperature sensing element is in contact with the other end of the spring pin, one end of the push rod is in contact with a lead, the other end of the push rod is in contact with an end of one side wall of the spring pin, and the temperature sensor is in contact with the other end of the spring pin. The length of the temperature sensing element is longer than the length of the push rod that contacts the spring pin in the direction of expansion and contraction of the spring, and when the temperature sensing element is triggered, the compressive elasticity of the spring is released and the other end of the push rod and the spring pin contact each other. The lead then separates from the contact due to its own elasticity, breaking the circuit. The above structure overcomes the problem of poor electrode contact due to deterioration of the temperature sensitive body. It also has the advantage of high temperature resistance.

Although the embodiments of the present application have been described above, this does not limit the scope of the claims of the present application, and equivalent changes made using the contents of the specification and drawings of the present application, or direct or indirect changes in the related technical fields. All such applications likewise fall within the protection scope of the present patent.

An embodiment, an embodiment, or one or more embodiments described herein means that at least one of the specific features, structures, or characteristics described with reference to the embodiment is means included in one embodiment. It should be noted that all references to the phrase "in one embodiment" herein do not necessarily refer to the same embodiment.

A number of details have been set forth herein. However, it is understood that the embodiments of the present application may be practiced without these detailed descriptions. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of the specification.

Note that the above embodiments are only for explaining the technical solution of the present application, and are not intended to limit it. Although the present application has been explained in detail with reference to the above-mentioned embodiments, those skilled in the art As can be understood, the technical solutions described in each of the above-mentioned embodiments may be modified or equivalent substitutions may be made for some technical features thereof, and these modifications and substitutions shall not be made in accordance with the corresponding The essence of the technical solution provided herein does not deviate from the spirit and scope of the technical solution of each embodiment of the present application.

1, Lead 2, Contact 3, Temperature sensitive element 4, Push rod 5, Shell 6, Guide plate 7, Electrode sheet 8, Mica sheet 9, Copper cap 10, Mounting plate 11, Rivet 12, Spring 13, Spring pin 131, Base 132, Pin body 133, Connection part 14, Resistance wire 15, Insulating mica sheet

FIG. 2 is a schematic structural diagram of a thermal fuse according to an embodiment of the present application. It is the arrangement|positioning form of the push rod of the thermal fuse based on the Example of this application. It is an arrangement|positioning form of the push rod of another thermal fuse based on the Example of this application. 1 is a structural exploded view of a thermal fuse according to Example 1 of the present application. FIG. It is a structural exploded view of the thermal fuse of Example 2 of this application. FIG. 2 is an assembled sectional view of a thermal fuse according to Example 2 of the present application. FIG. 2 is a partial structural schematic diagram of a thermal fuse according to Example 2 of the present application. FIG. 3 is a partial front view of a thermal fuse according to Example 2 of the present application. It is a structural exploded view of the thermal fuse of Example 3 of this application. FIG. 7 is an assembled sectional view of a thermal fuse according to Example 3 of the present application.

Referring to FIG. 4 , which is a first embodiment of the present application, FIG . 4 is a structural exploded view of the first embodiment of the present application. The thermal fuse of the present invention has two electrode sheets, each crimped to a ceramic case, the leads and contacts are spot welded to the two electrode sheets, respectively, the guide pin 17 and the holder 16 are integrally welded, and the holder 16, the floating spring 18 biases the bridge 19 so that it has a floating pressure when it contacts the contact 2, and the guide pin 17, the holder 16, the floating spring 18 and the bridge 19 are integrated. A push rod is formed, and a push rod spring 20 is disposed at the front end of the push rod. When the thermal fuse is not triggered, the push rod spring 20 is in a compressed state, and the resistance wire (regarding the effect), when the product is used in a circuit with a large rated current, the resistance wire exerts an arc-extinguishing effect, and the lead is removed from the contact point. (to prevent arcing when separated) is connected to a welding pin welded to the electrode sheet, the spring is placed inside the cavity of the ceramic case, the temperature sensor is placed inside the copper cap, and the upper end is connected to the spring pin. , the lower end of the pin body of the spring pin and the copper cap form a large clearance fit, the large gap is favorable for the melting and evacuation of the temperature sensor, and the upper end of the spring pin supports the two springs and attaches By being crimped to the ceramic case, the plate has the effect of transmitting temperature and fixing it, and the cover plate has a dust-proofing and sealing effect due to the gap between the rivet and the ceramic case.

Embodiment 3 of the present application is shown in FIGS. 10 and 11.
The difference from the second embodiment is that a resistance wire is added inside the shell. Specifically, a cavity is provided within the shell, an insulating mica sheet 15 and a resistance wire 14 are provided within the cavity, and the resistance wire 14 is electrically connected to a welding pin provided on the electrode sheet 7. The insulating mica sheet 15 is provided between the resistance wire 14 and the mounting plate 10. With the above structure, when the product is used in a circuit with a large rated current, the resistance wire exhibits an arc extinguishing effect and prevents arcing when the lead is separated from the contact.

As shown in FIGS. 5 to 8 , the thermal fuse according to the present application includes leads and contacts arranged opposite to each other, and further includes a spring mechanism, a temperature sensing element, and a push rod, the spring mechanism includes a spring and a spring pin, The spring is sheathed on one end of the spring pin. When the thermal fuse is not triggered, the spring is in a compressed state, the temperature sensitive element abuts the other end of the spring pin, one end of the push rod abuts a lead, and the other end of the push rod is in contact with the spring pin. The length of the temperature sensing element that abuts the end of one side wall of the pin in the direction of expansion and contraction of the spring is longer than the length of the push rod that abuts the spring pin in the direction of expansion and contraction of the spring.

Embodiment 2 of the present application is shown in FIGS. 5 to 8 .
The thermal fuse according to the present application includes a lead 1, a contact 2, a spring mechanism, a temperature sensing element 3, a push rod 4, a shell 5, a guide plate 6, an electrode sheet 7, a mica sheet 8, a copper cap 9, a mounting plate 10, and a rivet 11. In this embodiment, the material of the shell is ceramic or plastic. The material of the push rod is ceramic or plastic.

Embodiment 3 of the present application is shown in FIGS. 9 and 10 .
The difference from the second embodiment is that a resistance wire is added inside the shell. Specifically, a cavity is provided within the shell, an insulating mica sheet 15 and a resistance wire 14 are provided within the cavity, and the resistance wire 14 is electrically connected to a welding pin provided on the electrode sheet 7. The insulating mica sheet 15 is provided between the resistance wire 14 and the mounting plate 10. With the above structure, when the product is used in a circuit with a large rated current, the resistance wire exhibits an arc extinguishing effect and prevents arcing when the lead is separated from the contact.

Claims (10)

The thermal fuse includes a push rod and a push rod spring, and further includes a spring mechanism and a temperature sensing element, the spring mechanism includes a spring and a spring pin, the spring is sheathed on one end of the spring pin, and the thermal fuse When untriggered, the spring is in a compressed state, the temperature sensitive element abuts the other end of the spring pin, and one end of the push rod abuts the push rod spring, when the thermal fuse is untriggered. The push rod spring is in a compressed state, the other end of the push rod is in contact with the end of one side wall of the spring pin, and the length of the temperature sensing element in the direction of expansion and contraction of the spring is such that the length of the temperature sensing element in the direction of expansion and contraction of the spring is such that it comes into contact with the spring pin in the direction of expansion and contraction of the spring. A thermal fuse characterized by being longer than the length of the contacting push rod. The spring pin comprises a base, two pin bodies respectively provided on the same side of the opposite ends of the base, and a connection part provided in the base, the connection part and the pin body being on different sides of the base, 2. The spring according to claim 1, wherein the spring is externally mounted on the pin body, the temperature sensing element abuts on the connecting portion, and the other end of the push rod abuts on a portion of the base located between the two pin bodies. Thermal fuses listed. The thermal fuse further includes a shell, and one end of the shell is provided with two electrode sheets spaced apart from each other, and the two electrode sheets correspond electrically to the leads and contacts in one-to-one correspondence. The thermal fuse according to claim 2, wherein the thermal fuse is connected. 4. The thermal fuse according to claim 3, wherein a guide plate is provided inside the shell, and the guide plate is provided corresponding to the position of the push rod. 4. The thermal fuse according to claim 3, wherein a copper cap is provided inside the shell, and the temperature sensing element is provided within the copper cap. The connecting part has a cylindrical shape, the inner space of the copper cap has a cylindrical shape, the temperature sensing element has a cylindrical shape, the outer diameter of the connecting part is equal to the outer diameter of the temperature sensing element, and the copper cap has a cylindrical shape. The thermal fuse according to claim 5, wherein an inner diameter of the connecting portion is larger than an outer diameter of the connecting portion. The shell further includes a mounting plate having an opening at the other end of the shell, the mounting plate being fixed to the opening of the shell by rivets to seal the opening, and the copper cap 6. The thermal fuse according to claim 5, wherein the thermal fuse is in contact with an inner wall of the mounting plate. A cavity is provided in the shell, an insulating mica sheet and a resistance wire are provided in the cavity, the resistance wire is electrically connected to a welding pin provided on the electrode sheet, and the insulating mica sheet is connected to the resistance wire. 8. The thermal fuse according to claim 7, wherein the thermal fuse is provided between the thermal fuse and the mounting plate. 4. The thermal fuse according to claim 3, wherein the shell is made of ceramic or plastic. 2. The thermal fuse according to claim 1, wherein the push rod is made of ceramic or plastic.