CN117976488A - Heavy-current automatic protection element - Google Patents

Abstract

The invention relates to the technical field of short-circuit protection elements, in particular to a high-current automatic protection element, which comprises: a base; a pair of main loop electrodes respectively arranged on the base and conducted through conductors between the electrodes; the conductors between the electrodes are respectively connected with each main loop electrode through fusible bonding parts; a spring compressed by the conductor between the electrodes; when the target temperature is reached, the fusible link breaks under the urging of the spring to separate the inter-electrode conductor from the main return electrode. The beneficial effects are that: the fuse is replaced by a fusible bonding part welded between the main loop electrode and the conductor between the electrodes, and the fusible bonding part has larger sectional area on a current path compared with a sheet material, so that the resistance of the fusible bonding part is obviously reduced on the basis of not changing the alloy resistivity, and the whole device meets the requirement of a heavy current application scene; on the basis, in order to avoid the problem that the metal between the electrodes is not completely separated when the fusible element is melted, a spring is further arranged to separate the fusible element from the electrode.

Description

Heavy-current automatic protection element

Technical Field

The invention relates to the technical field of short-circuit protection elements, in particular to a high-current automatic protection element.

Background

The high-current automatic protection element is an electronic element for protecting a circuit from faults such as overload and short circuit. It can detect abnormal large current in the circuit and cut off the circuit rapidly to prevent the damage of the circuit or the fire hazard. Generally, high current automatic protection elements have the characteristic of fast response, enabling to switch the circuit within a few milliseconds. It also has the advantages of high reliability, long service life, convenient installation, etc. The method is widely applied to the fields of power systems, industrial equipment, household appliances and the like.

In the prior art, there are many schemes suitable for protecting large currents. For example, chinese patent 201480044945.1 discloses a protection element and a battery pack comprising a first insulating base; and a fusible conductor mounted on a surface of the first insulating base; the surface of the first insulating base is provided with a suction hole for sucking the melted fusible conductor, the suction hole is a through hole or a non-through hole which is formed on the inner surface and is arranged along the thickness direction of the first insulating base, the fusible conductor contains low-melting-point metal and high-melting-point metal, the fusible conductor is an inner layer of the low-melting-point metal, and the outer layer of the fusible conductor is a coating structure of the high-melting-point metal. The current capacity at the time of overcurrent protection can be ensured and the fuse can be reliably fused according to the heat generation of the heating element.

However, in the practical implementation process, the inventor finds that along with popularization of the high-current application scene in the market, the resistance of the rectangular fusible conductor material in the device is difficult to reduce and is severely limited by the alloy resistivity, so that the resistance of the device is difficult to meet the requirement of the high-current application scene, and the application scene is restricted.

Disclosure of Invention

In view of the above problems in the prior art, an automatic protection device for high current is now provided.

The specific technical scheme is as follows:

a high current automatic protection element comprising:

A base;

A pair of main loop electrodes respectively arranged on the base and respectively connected with an external circuit, wherein the main loop electrodes are communicated through an inter-electrode conductor;

a fusible binder disposed on the main loop electrodes, respectively, the inter-electrode conductors being connected to each of the main loop electrodes through the fusible binder, respectively;

a spring, a first end of which is fixed on the base, a second end of which is connected with the inter-electrode conductor, and which is compressed by the inter-electrode conductor;

When the target temperature is reached, the fusible link breaks under the urging of the spring to separate the inter-electrode conductor from the main return electrode.

On the other hand, still be provided with on the base:

An auxiliary electrode connected to the external circuit;

the heating body is arranged on the base and is positioned below the main loop electrode and the auxiliary electrode;

the heating body is connected with the auxiliary electrode, and is driven by the power supply current of the external circuit to generate heat, and the fusible joint is heated to the target temperature when the power supply current exceeds the current limit value.

In another aspect, the heating element includes:

the electrode wire is positioned on the base and is connected with the auxiliary electrode;

The resistor layer is connected across the electrode wire;

an insulating layer formed on the resistive layer;

and the inner electrodes are respectively connected with the electrode wires and the inter-electrode conductors.

In another aspect, the heating element further includes: the ground coat layer is formed on the base, the electrode wire is formed on the ground coat layer, and the resistor layer is formed on the ground coat layer and covers the electrode wire;

The electrode wire includes:

The third terminal bonding pad is formed on the primer layer and is connected with the auxiliary electrode;

an inner electrode wire disposed on the first and second predetermined regions corresponding to the main loop electrode, respectively, and connected with the third terminal pad, respectively;

An external electrode line disposed in the first and second predetermined regions, respectively, and connected to the internal electrode;

The resistive layer includes:

a left heating element formed in the first predetermined region;

And a right heating element formed in the second predetermined region.

On the other hand, the inter-electrode conductor is a sheet-shaped object in a shape like a Chinese character 'ji' in a side view, and a containing cavity is formed below the inter-electrode conductor;

When the spring is compressed, the spring is accommodated in the accommodating cavity;

a pair of first bonding pads and a pair of second bonding pads are respectively arranged at four corners of the inter-electrode conductor in the overlook direction;

the first bonding pads are respectively connected with the main loop electrode;

the second bonding pad is fixedly connected with the base.

On the other hand, in the top view direction, a fixed through hole is formed in the central region of the inter-electrode conductor;

the automatic protection element further comprises an upper shell, wherein the upper shell is fixed on the base and wraps the inter-electrode conductor;

The inner cavity of the upper shell is provided with a guide post along the vertical direction at a position corresponding to the fixed through hole;

the guide post passes through the fixing through hole;

when the fusible link breaks, the inter-electrode conductor moves along the guide post.

On the other hand, a narrow part with a preset width is arranged in the vertical direction of the connecting line of the fixing through hole, the main loop electrode and the auxiliary electrode, and the resistance value of the automatic protection element is adjusted by adjusting the preset width.

On the other hand, four corners of the lower edge part of the upper shell are respectively provided with upper cover fixing columns;

A plurality of upper cover fixing holes are formed in the base in the area corresponding to the upper cover fixing columns;

the upper cover fixing column is matched with the upper cover fixing hole to fix the upper shell.

On the other hand, the main loop electrode and the auxiliary electrode are respectively provided with electrode fixing lugs at two ends close to the first side of the base;

the base is provided with corresponding lug-shaped grooves at the positions where the main loop electrode and the auxiliary electrode are scheduled to be installed;

The electrode fixing lugs and the lug-shaped grooves cooperate to restrict movement of the main loop electrode, the auxiliary electrode and the auxiliary electrode in a horizontal plane.

On the other hand, the main loop electrode and the auxiliary electrode are respectively provided with an element fixing hole, and the main loop electrode and the auxiliary electrode are connected with the external circuit through the element fixing holes.

The technical scheme has the following advantages or beneficial effects:

Aiming at the problem of poor application effect caused by over-high resistance of the strip alloy fuse wire in the prior art, in the scheme, the strip fusible conductor is improved and replaced by a fusible connector welded between a main loop electrode and an inter-electrode conductor, and the fusible connector has a larger sectional area on a current path compared with a sheet material, so that the resistance of the fusible connector is obviously reduced on the basis of not changing the alloy resistivity, and the whole device meets the requirement of a heavy current application scene; on the basis, in order to avoid the problem that the metal between the electrodes is not completely separated when the fusible element is melted, a spring is further arranged to separate the fusible element from the electrode.

Drawings

Embodiments of the present invention will now be described more fully with reference to the accompanying drawings. The drawings, however, are for illustration and description only and are not intended as a definition of the limits of the invention.

FIG. 1 is an overall schematic of an embodiment of the present invention;

FIG. 2 is a top view of an embodiment of the present invention;

FIG. 3 is a schematic view of an electrode according to an embodiment of the present invention;

FIG. 4 is a schematic cross-sectional view of a heat-generating body in an embodiment of the invention;

FIG. 5 is a schematic view of an electrode wire according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of an inter-electrode conductor in an embodiment of the invention;

FIG. 7 is a schematic view of an upper cover according to an embodiment of the present invention;

fig. 8 is a schematic view of a base in an embodiment of the invention.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.

The invention is further described below with reference to the drawings and specific examples, which are not intended to be limiting.

The invention comprises the following steps:

a high current automatic protection element, as shown in fig. 1 and 2, comprising:

A base 1;

a pair of main loop electrodes 2A, 2B respectively provided on the base 1 and connected to an external circuit, the pair of main loop electrodes 2A, 2B being electrically connected to each other via an inter-electrode conductor 3;

A fusible link 4, the fusible links 4 being provided on the main loop electrodes 2A, 2B, respectively, the inter-electrode conductor 3 being connected to each of the main loop electrodes 2A, 2B through the fusible links 4, respectively;

A spring 5, a first end of the spring 5 is fixed on the base 1, a second end of the spring 5 is connected with the inter-electrode conductor 3, and the spring 5 is compressed by the inter-electrode conductor 3;

when the target temperature is reached, the fusible link 4 breaks under the urging of the spring 5, so that the inter-electrode conductor 3 and the main return electrodes 2A, 2B are separated.

Specifically, in the embodiment, the strip-shaped fusible conductor is replaced by the fusible link 4, and the fusible link 4 is formed on the surfaces of the main loop electrode 2A and the main loop electrode 2B for welding the inter-electrode conductor 3 to the main loop electrode 2A and the main loop electrode 2B respectively, aiming at the problem that the application effect of the strip-shaped alloy fuse in the prior art is poor due to the excessively high resistance value. The main loop electrode 2A, the main loop electrode 2B and the inter-electrode conductor 3 do not need to bear the function of being melted by heat, and can be realized by adopting a material with low resistivity; compared with the traditional strip-shaped and columnar fuse wire, the fusible link 4 in the shape of a coating and a sheet has larger sectional area, and the resistance value is greatly reduced under the condition that the resistivity of the alloy is not changed; through the arrangement, the automatic protection element has a lower resistance value, and can effectively meet the low resistance requirement of a device in a large current scene.

Further, considering the coated fusible link 4, adhesion with the inter-electrode metal may occur when a large current is heated and melted, resulting in a problem that the circuit is not completely cut off, in this embodiment, a spring 5 is provided under the inter-electrode conductor 3 in a compressed state. When the target temperature is reached, the fusible link 4 is softened or melted by heating, the tensile strength of the fusible link is obviously reduced, and at the moment, the spring 5 pushes the inter-electrode conductor 3 to move upwards so as to enable the fusible link 4 to be completely broken, and the loop is effectively cut off.

In the implementation process, the automatic protection element is arranged in a circuit as a whole, is connected into the circuit through the main circuit electrode 2A and the main circuit electrode 2B, and senses the current on the circuit; and automatically cut off when the current exceeds the limit value. In other embodiments, an auxiliary electrode 2C is also included, which is connected to the circuit together with the main loop electrodes 2A, 2B for fuse protection. The base 1 is a substrate for setting the above devices, and is usually made of ceramic material or other insulating materials; the main loop electrode 2A, the main loop electrode 2B, the auxiliary electrode 2C, and the inter-electrode conductor 3 are structures in which a certain low-resistivity material, such as a metal material, is processed to obtain a specific shape, which is mainly used to pass current. The fusible link 4 is a material having a relatively low melting point, such as an alloy fuse, etc., which melts when a certain temperature is reached by a large current, generates heat, and causes the passage to be opened. In general, the fusible link 4 is held between the main return electrode 2A and the inter-electrode conductor 3 and between the main return electrode 2B and the inter-electrode conductor 3 in a sheet-like shape, and maintains a large contact area to maintain a low resistance value. Depending on the embodiment, it is also possible to provide the foil, the coating or other structures with different shapes, which can perform the corresponding functions.

In one embodiment, the base 1 is further provided with:

An auxiliary electrode 2C, the auxiliary electrode 2C being connected to an external circuit;

the heating element 6 is arranged on the base 1 and is positioned below the main loop electrode 2A and the main loop electrode 2B;

the heating element 6 is connected to the auxiliary electrode 2C, and the heating element 6 is driven by a supply current of an external circuit to generate heat, and heats the fusible link 4 to a target temperature when the supply current exceeds a current limit value.

Specifically, in order to achieve a good separation effect, in the present embodiment, an auxiliary electrode 2C and a heating element 6 are also provided on the base 1 to be connected into a circuit. Wherein the auxiliary electrode 2C is connected to an external circuit to take in the current on the wire, and then the heating body 6 heats up in accordance with the collected power supply current, and heats the fusible link 4 to a target temperature when the power supply current exceeds a current limit value, so that the fusible link 4 is melted and broken. The current limit value of the automatic protection element can be well regulated by controlling the current-temperature rise curve of the heating element 6, so that the stable melting process of the fusible bonding part 4 is realized; meanwhile, the heating element 6 is not arranged on the main loop, namely the main loop electrode 2A-fusible joint 4-electrode conductor 3-fusible joint 4-main loop electrode 2B, so that the influence of the resistance on the whole resistance of the element is reduced, and the requirement of low resistance under a heavy current scene is met.

In the implementation process, in order to achieve better productivity, as shown in fig. 3, the main loop electrode 2A, the main loop electrode 2B, and the auxiliary electrode 2C have the same electrode structure. Specifically, the main circuit electrode 2A, the main circuit electrode 2B, and the auxiliary electrode 2C each have a rectangular parallelepiped shape in the main body 200, and an element fixing hole 201 is provided in the middle of the main body 200, and the main circuit electrode 2A, the main circuit electrode 2B, and the auxiliary electrode 2C are connected to an external circuit through the element fixing hole 201. A bonding pad 200 is provided on one side of the body portion 200, and the bonding pad 200 is provided with a fusible bonding member 4 for solder-fixing with the inter-electrode conductor 3.

In one embodiment, as shown in fig. 4 and 5, the heating element 6 includes:

An electrode wire 61, the electrode wire 61 being located on the base, the electrode wire 61 being connected to the auxiliary electrode 2C;

A resistive layer 62, the resistive layer 62 being connected across the electrode line 61;

an insulating layer 63, the insulating layer 63 being formed on the resistive layer 62;

the inner electrode 64, the inner electrode 64 is connected to the electrode line 61 and the inter-electrode conductor 3, respectively.

Specifically, in order to achieve a better fusing effect, in this embodiment, the heating element 6 is configured to form a heating loop by sequentially stacking an electrode wire, a resistance layer and an inner electrode, so that effective fusing of the fusible link 4 when the current exceeds the limit value is achieved; meanwhile, the insulating layer covers the resistor layer and is led out through the inner electrode, so that the problem that the resistor is too low and cannot normally generate heat due to the fact that the chip resistor layer directly contacts the main loop electrode 2A and the main loop electrode 2B above is avoided.

In one embodiment, as shown in fig. 4 and 5, the heating element 6 further includes: a primer layer 60 formed on the base 1, an electrode line formed on the primer layer 60, and a resistor layer 62 formed on the primer layer 60 and covering the electrode line 61;

The electrode wire 61 includes:

A third end pad 611, the third end pad 611 being formed on the primer layer 60, the third end pad 611 being connected with the auxiliary electrode 2C;

An inner electrode line 612, the inner electrode line 612 being disposed on a first predetermined region corresponding to the main loop electrode 2A and a second predetermined region corresponding to the main loop electrode 2B, respectively, and being connected to the third terminal pad 611, respectively;

An external electrode line 613, the external electrode line 613 being disposed in the first predetermined region and the second predetermined region, respectively, and being connected to the internal electrode 64;

The resistive layer 62 includes:

a left heating element formed in a first predetermined region;

a right heating element formed in the second predetermined region.

Specifically, in order to achieve a better heating effect, in this embodiment, a primer layer 60 is printed on the base 1 in advance, and electrode wires 61 are printed above the primer layer 60, including inner electrode wires 612 and outer electrode wires 613, where the inner electrode wires 612 on both sides are located near the middle of the first predetermined area and the second predetermined area, and are connected and fixed with the auxiliary electrode 2C through a third terminal pad 611. Meanwhile, the portions of the first predetermined area and the second predetermined area near the outside are provided with the external electrode wire 613 and are connected to the inter-electrode conductor 2 through the internal electrode 64, and the lengths of the resistive layer 62 and the insulating layer 63 in this direction are short, so that the internal electrode 64 is not covered; when the resistive layer 62 is covered, the left heating element or the right heating element is connected across the inner electrode line 612 and the outer electrode line 613 at the same time to form a loop, and generates heat according to an input current.

In one embodiment, as shown in fig. 6, the inter-electrode conductor 3 is shaped like a Chinese character 'ji' in a side view, and a receiving cavity is formed below the inter-electrode conductor 3;

when the spring 5 is compressed, the spring 5 is received in the receiving chamber;

A pair of first pads 31 and a pair of second pads 32 are provided at four corners of the inter-electrode conductor 3 in a plan view;

The first pads 31 are connected to the main loop electrode 2A and the main loop electrode 2B, respectively;

the second bonding pad 32 is fixedly connected with the base 1.

Specifically, in order to achieve a better device integration effect, in this embodiment, the inter-electrode conductor 3 is configured as a sheet-like shaped piece, which is welded and fixed with the main loop electrode 2A and the main loop electrode 2B through the first bonding pad on the supporting leg via the fusible bonding element 4, and is connected with the base 1 through the second bonding pad 32 for auxiliary fixation, when the stable fixation of the inter-electrode conductor 3 is achieved, the inter-electrode conductor 3 can only be lifted up at a specific angle after the first bonding pad 31 is detached through the connection between the second bonding pad 32 and the base 1, so that the risk of re-connecting loops caused by shaking of the inter-electrode conductor 3 in the cavity of the element when the fusible bonding element 4 is melted is avoided.

In one embodiment, as shown in fig. 6 and 7, a fixing through hole 33 is opened in a central region of the inter-electrode conductor 3 in a top view direction;

the automatic protection element further comprises an upper shell 7, wherein the upper shell 7 is fixed on the base 1 and wraps the inter-electrode conductor 3;

the position of the inner cavity of the upper shell 7 corresponding to the fixed through hole is provided with a guide post 71 along the vertical direction;

The guide post 71 passes through the fixing through hole 33;

when the fusible link 4 breaks, the inter-electrode conductor 3 moves along the guide post.

Specifically, in order to achieve a better restraining effect on the inter-electrode conductor 3, in this embodiment, a fixing through hole is further formed in the central area of the inter-electrode conductor 3, and the fixing through hole is matched with the guide post 17 in the upper shell 7, so that after the fusible bonding element 4 breaks, the inter-electrode conductor 3 can only move along the guide post, and cannot displace in the horizontal direction, and the risk of loop connection is avoided.

In one embodiment, a narrow portion with a predetermined width is arranged in the vertical direction of the connection line between the fixing through hole and the main loop electrode 2A, 2B, and the resistance value of the automatic protection element is adjusted by adjusting the predetermined width.

Specifically, in order to further increase the application range of the device, in this embodiment, a narrow portion is prepared on the fixing through hole, so that the resistance value of the portion is changed; the resistance of the automatic protection element can be changed to a certain extent by adjusting the preset width of the narrow part, so that the automatic protection element is suitable for occasions needing a certain resistance.

Further, in this case, when a current flows through the inter-electrode conductor 3, the temperature rise due to the heat generation amount at the rated current is insufficient at the time of balancing to make the strength of the fusible link 4 lower than the prescribed strength, and when an overcurrent condition occurs, the heat generation amount of the narrow portion is also increased, and when the current reaches the prescribed current, the temperature rise due to the heat generation amount of the device makes the strength of the link lower than the prescribed strength for the prescribed time, so that the link is separated with the assistance of the spring 5, and the circuit is separated accordingly, thereby achieving a good separation effect.

In one embodiment, as shown in fig. 7 and 8, four corners of the lower edge portion of the upper case 7 are provided with upper cover fixing posts 73, respectively;

A plurality of upper cover fixing holes 11 are formed in the base 1 in the area corresponding to the upper cover fixing columns 73;

The upper cover fixing posts 73 are engaged with the upper cover fixing holes 11 to fix the upper housing.

Specifically, in order to achieve a better fixing effect of the device, in this embodiment, corresponding electrode fixing holes are respectively formed on the main loop electrode 2A, the main loop electrode 2B and the auxiliary electrode 2C, and the electrode fixing holes are matched with upper cover fixing holes that are circumferentially arranged on the base 1. The upper cover fixing column passes through the electrode fixing hole and the upper cover fixing hole in sequence to be fixedly connected with the base 1, so that stable connection among the upper shell 7, the main loop electrode 2A, the main loop electrode 2B, the auxiliary electrode 2C and the base 1 is realized.

In one embodiment, as shown in fig. 3, 7 and 8, the main loop electrode 2A, the main loop electrode 2B and the auxiliary electrode 2C are respectively provided with electrode fixing lugs 204 at both ends proximate to the first side of the base 1;

The base 1 is provided with corresponding lug-shaped grooves 12 at the positions where the main loop electrode 2A, the main loop electrode 2B and the auxiliary electrode 2C are scheduled to be installed;

The electrode fixing lugs 204 and the lug grooves 12 cooperate to restrict movement of the main loop electrode 2A, the main loop electrode 2B, and the auxiliary electrode 2C in the horizontal plane.

Specifically, in order to achieve a better fixing effect, in this embodiment, electrode fixing lugs are respectively disposed at two ends of the main loop electrode 2A, the main loop electrode 2B and the auxiliary electrode 2C, which are close to the first edge of the base 1, and corresponding lug-shaped grooves are formed on the base 1; when the main loop electrode 2A, the main loop electrode 2B, and the auxiliary electrode 2C are mounted to the base 1, they fall down in the vertical direction so that the electrode fixing lugs 204 fall into the lug-shaped grooves 12; at this time, when the main loop electrode 2A, the main loop electrode 2B and the auxiliary electrode 2C move in the horizontal direction, the electrode fixing lug 204 is partially supported by the lug-shaped groove 12, so that rotation and displacement are not easy to occur, and a good fixing effect is achieved.

Further, in order to achieve a better fixing effect, in this embodiment, elongated electrode mounting grooves 13A, 13B, and 13C are further formed in the base 1, for fixing the main loop electrode 2A, the main loop electrode 2B, and the auxiliary electrode 2C, respectively; a pair of main loop electrode mounting holes 14 are respectively arranged in the electrode mounting grooves 13A, 13B and 13C, main loop electrode mounting holes 203 are arranged at corresponding positions on the main loop electrode 2A, the main loop electrode 2B and the auxiliary electrode 2C, and auxiliary electrode mounting holes 72 are arranged at corresponding positions on the lower edge part of the upper cover 7; when the main loop electrode 2A, the main loop electrode 2B and the auxiliary electrode 2C need to be installed, the main loop electrode installation hole 14, the main loop electrode installation hole 203 and the auxiliary electrode installation hole 72 are penetrated in sequence through rivets to realize installation; in addition, the central region 15 of the base 1 is used for disposing the heating element 6;

The foregoing is merely illustrative of the preferred embodiments of the present invention and is not intended to limit the embodiments and scope of the present invention, and it should be appreciated by those skilled in the art that equivalent substitutions and obvious variations may be made using the description and illustrations of the present invention, and are intended to be included in the scope of the present invention.

Claims (10)

1. A high current automatic protection element, comprising:

A base;

A pair of main loop electrodes respectively arranged on the base and respectively connected with an external circuit, wherein the main loop electrodes are communicated through an inter-electrode conductor;

a fusible binder disposed on the main loop electrodes, respectively, the inter-electrode conductors being connected to each of the main loop electrodes through the fusible binder, respectively;

a spring, a first end of which is fixed on the base, a second end of which is connected with the inter-electrode conductor, and which is compressed by the inter-electrode conductor;

When the target temperature is reached, the fusible link breaks under the urging of the spring to separate the inter-electrode conductor from the main return electrode.

2. The automatic protection element according to claim 1, wherein the base is further provided with: an auxiliary electrode connected to the external circuit;

the heating body is arranged on the base and is positioned below the main loop electrode and the auxiliary electrode;

the heating body is connected with the auxiliary electrode, and is driven by the power supply current of the external circuit to generate heat, and the fusible joint is heated to the target temperature when the power supply current exceeds the current limit value.

3. The automatic protection element according to claim 2, wherein the heating element includes:

the electrode wire is positioned on the base and is connected with the auxiliary electrode;

The resistor layer is connected across the electrode wire;

an insulating layer formed on the resistive layer;

and the inner electrodes are respectively connected with the electrode wires and the inter-electrode conductors.

4. The automatic protection element according to claim 3, wherein the heat generating body further comprises: the ground coat layer is formed on the base, the electrode wire is formed on the ground coat layer, and the resistor layer is formed on the ground coat layer and covers the electrode wire;

The electrode wire includes:

The third terminal bonding pad is formed on the primer layer and is connected with the auxiliary electrode;

an inner electrode wire disposed on the first and second predetermined regions corresponding to the main loop electrode, respectively, and connected with the third terminal pad, respectively;

An external electrode line disposed in the first and second predetermined regions, respectively, and connected to the internal electrode;

The resistive layer includes:

a left heating element formed in the first predetermined region;

And a right heating element formed in the second predetermined region.

5. The automatic protection element according to claim 1, wherein the inter-electrode conductor is in a shape of a Chinese character 'ji' in a side view, and a receiving cavity is formed under the inter-electrode conductor;

When the spring is compressed, the spring is accommodated in the accommodating cavity;

a pair of first bonding pads and a pair of second bonding pads are respectively arranged at four corners of the inter-electrode conductor in the overlook direction;

the first bonding pads are respectively connected with the main loop electrode;

the second bonding pad is fixedly connected with the base.

6. The automatic protection element according to claim 5, wherein a central region of the inter-electrode conductor is provided with a fixing through hole in a top view direction;

the automatic protection element further comprises an upper shell, wherein the upper shell is fixed on the base and wraps the inter-electrode conductor;

The inner cavity of the upper shell is provided with a guide post along the vertical direction at a position corresponding to the fixed through hole;

the guide post passes through the fixing through hole;

when the fusible link breaks, the inter-electrode conductor moves along the guide post.

7. The automatic protection device according to claim 6, wherein the fixing hole is provided with a narrow portion with a predetermined width in a vertical direction of the connection line between the fixing hole and the main loop electrode and the auxiliary electrode, and the resistance value of the automatic protection device is adjusted by adjusting the predetermined width.

8. The automatic protection element according to claim 6, wherein four corners of the lower edge portion of the upper case are respectively provided with upper cover fixing posts;

A plurality of upper cover fixing holes are formed in the base in the area corresponding to the upper cover fixing columns;

the upper cover fixing column is matched with the upper cover fixing hole to fix the upper shell.

9. The automatic protection element according to claim 2, wherein the main loop electrode and the auxiliary electrode are respectively provided with electrode fixing lugs at both ends proximate to the first side of the base;

the base is provided with corresponding lug-shaped grooves at the positions where the main loop electrode and the auxiliary electrode are scheduled to be installed;

The electrode fixing lugs and the lug-shaped grooves cooperate to restrict movement of the main loop electrode, the auxiliary electrode and the auxiliary electrode in a horizontal plane.

10. The automatic protection element according to claim 2, wherein element fixing holes are respectively formed in the main loop electrode and the auxiliary electrode, and the main loop electrode and the auxiliary electrode are connected with the external circuit through the element fixing holes.