Self-resetting three-terminal crowbar

Abstract

The application discloses a self-recoverable three-terminal protector, which comprises a substrate, a first electrode, a second electrode, a third electrode, a first electric heating part, a second electric heating part, a turnover plate and a crossbar are arranged on the substrate; the turnover plate is in an overall arc structure, comprising an arch part and a supporting leg located at both ends of the arch part; the crossbar comprises a supporting point and a supporting arm located at both ends of the supporting point, a connecting contact for electric connection is arranged on each of the two supporting arms, the turnover plate comprises an active layer facing away from the crossbar and a passive layer facing the crossbar, and the turnover plate has a first state of arching towards the crossbar and a second state of arching away from the crossbar; the turnover plate further comprises a shunt layer between the active layer and the passive layer, and the conductivity of the shunt layer is much greater than that of the active layer and the passive layer. The three-terminal protector can be repeatedly used through the turnover movement of the turnover plate based on temperature; in addition, the response speed of the three-terminal protector is effectively improved through the high-conductivity shunt layer arranged in the middle of the turnover plate.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic protection devices, in particular to a self-recoverable three-terminal fuse. Background Art

[0002] Three-terminal fuses, which provide both overcurrent and overvoltage protection, are widely used in battery management systems and other fields as critical circuit protection components. Currently, most commonly used three-terminal fuses disconnect the circuit by melting a built-in alloy fuse link under high-temperature conditions. These are disposable electronic products, requiring replacement after troubleshooting. This increases labor and financial costs, while also wasting resources. Summary of the Invention

[0003] The purpose of the present invention is to provide a three-terminal fuse which can be reused multiple times and can be restored by itself.

[0004] To achieve the above-mentioned object, the present invention provides a self-recoverable three-terminal fuse, comprising a substrate, on which are provided a first electrode, a second electrode, a third electrode, a first electric heating portion, a second electric heating portion, a flip plate, and a crossbar, which are separated from each other; the flip plate is located between the crossbar and the substrate;

[0005] The first electrode and the second electrode are two current control terminals, and the third electrode is a voltage control terminal;

[0006] The flip plate is an overall arched structure, comprising an arched portion and supporting legs located at both ends of the arched portion;

[0007] The crossbar includes a fulcrum and support arms located at both ends of the fulcrum, and the two support arms are respectively provided with a connection contact for electrical connection, and the two connection contacts are electrically connected;

[0008] The flip plate includes an active layer facing away from the crossbar and a passive layer facing the crossbar, wherein the active layer has a greater thermal expansion coefficient than the passive layer, so that at a first target temperature, the flip plate has a first state arched toward the crossbar, and at a second target temperature, the flip plate has a second state arched away from the crossbar;

[0009] By means of the flipping change of the flip plate between the first state and the second state, the two legs can drive the two arms of the crossbar to move up and down with the fulcrum as the center, so that the two connection contacts are respectively in contact with or separated from the first electrode and the second electrode;

[0010] The first electric heating part is capable of generating heat based on the current between the two connection contacts, and a heat conduction channel is provided between the first electric heating part and the flip plate;

[0011] The second electric heating portion is located between the base plate and the flip plate. In the first state, the two legs abut against the second electric heating portion; in the second state, the arched portion abuts against the second electric heating portion.

[0012] The second electric heating portion is electrically connected to the third electrode, and the flip plate is conductive, so that the second electric heating portion is electrically connected to the connection contact by means of the flip plate;

[0013] The flip plate further includes a shunt layer located between the active layer and the passive layer, and the conductivity of the shunt layer is much greater than that of the active layer and the passive layer.

[0014] Preferably, the material of the active layer includes any one of Mn-Ni-Cr-Cu alloy, Mn-Ni-Cu alloy, Ni-Cr-Fe alloy, Ni-Mn-Fe alloy and Cu-Zn alloy; the material of the passive layer includes any one of Fe-Ni alloy and Fe-Ni-Mn alloy, and the shunt layer includes any one of Cu-Ag alloy, Cu-Cd alloy, pure copper and pure nickel.

[0015] Preferably, a thickness ratio α of the active layer to the passive layer satisfies: 1 / 2≤α≤2.

[0016] Preferably, the overall thickness h1 of the flip plate satisfies: 50 μm ≤ h1 ≤ 200 μm, and the thickness h2 of the diversion layer satisfies: 3 μm ≤ h2 ≤ 8 μm.

[0017] Preferably, the crossbar is a conductive metal sheet with elasticity, and the two connection contacts are electrically connected by means of the crossbar.

[0018] Preferably, the crossbar can generate heat due to its own resistance under the action of the current between the two connection contacts, so that the crossbar serves as the first electric heating part.

[0019] Preferably, the material of the crossbar includes any one of Cu-Ni-Si-Mg alloy and Cu-Zr alloy.

[0020] Preferably, the thickness h3 of the crossbar satisfies: 80 μm ≤ h3 ≤ 300 μm.

[0021] Preferably, the first electrode, the second electrode and the third electrode each include a first electrode sheet arranged on the upper surface of the substrate and a second electrode sheet arranged on the lower surface of the substrate, and each pair of the first electrode sheet and the second electrode sheet are electrically connected through a third electrode sheet that passes through the upper and lower surfaces of the substrate.

[0022] Preferably, the two connecting contacts are spherical structures.

[0023] Compared with the prior art, the three-terminal fuse provided by the above technical solution of the present invention has the following advantages: when a circuit fault occurs, the first electric heating part or the second electric heating part transfers excessive heat to the flip plate, which moves to disconnect the circuit. When the circuit fault is resolved, the temperature of the flip plate drops and it flips again, thereby driving the circuit to enter the connected state again, thereby realizing the reuse of the three-terminal fuse without the need for replacement.

[0024] In addition, the active layer and passive layer that can drive the flip plate to flip generally have low conductivity. Therefore, by setting a high-conductivity shunt layer in the middle of the flip plate, when the high-voltage fuse is triggered, the heating circuit of the second electric heating part can be quickly connected, thereby improving the response speed of the three-terminal fuse and avoiding the flip plate from being burned due to excessive current flowing through the flip plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 FIG1 is a three-terminal structural diagram of a three-terminal fuse in one embodiment of the present invention.

[0026] Figure 2 for Figure 1 side view.

[0027] Figure 3 This is a three-terminal structural diagram of another embodiment of the present invention, showing a three-terminal fuse in a first state.

[0028] Figure 4 for Figure 3 side view.

[0029] Figure 5 FIG1 is a three-terminal structural diagram of a three-terminal fuse in another embodiment of the present invention in a second state.

[0030] Figure 6 for Figure 5 side view.

[0031] Figure 7 for Figure 3 Exploded diagram of .

[0032] Figure 8 3D is a three-dimensional structural diagram of the flip plate in an embodiment of the present invention.

[0033] Figure 9 for Figure 8 side view.

[0034] Figure 10 3D is a three-dimensional structural diagram of a substrate in an embodiment of the present invention.

[0035] Figure 112 is a bottom structural diagram of the substrate in an embodiment of the present invention.

[0036] Figure 12 4 is a circuit structure diagram of a three-terminal fuse in a first state according to an embodiment of the present invention.

[0037] Figure 13 4 is a circuit structure diagram of a three-terminal fuse in a second state according to an embodiment of the present invention.

[0038] Figure 14 It is a structural diagram of a three-terminal fuse in the prior art. DETAILED DESCRIPTION

[0039] In order to explain the technical content, structural features, achieved objectives and effects of the present invention in detail, the following is a detailed description in conjunction with the embodiments and the accompanying drawings.

[0040] This embodiment discloses a three-terminal fuse for circuit protection, which is particularly suitable for battery management circuits. Compared with traditional three-terminal fuses, the three-terminal fuse in this embodiment has a self-recovery function. To facilitate understanding of the characteristics of the three-terminal fuse in this embodiment, the following first describes the working mechanism of the traditional three-terminal fuse.

[0041] like Figure 14 A traditional three-terminal fuse consists of three terminals, two fuses made of alloy metal, and a heating element. The fuses can melt in the event of an overcurrent or short circuit, cutting off the circuit and providing protection. The three terminals are two first terminals for current control and a second terminal for voltage control. The two fuses are connected in series between the two first terminals.

[0042] Taking a battery charge and discharge circuit as an example, when the charging current is too high, the fuse between the two first terminals will directly blow. When the battery is overcharged and the voltage is too high, the controller will send a low level to the second terminal, turning on the circuit where the heating wire is located. The heating wire begins to heat up and blow the fuse, thus achieving overcurrent and overvoltage protection.

[0043] From this we can see that when the fuse is triggered, the fuse is blown. After the fault is eliminated, a new fuse needs to be replaced.

[0044] In this regard, in order to make the three-terminal fuse have a self-recovery function, that is, after the fault is eliminated, the fuse can automatically recover without replacing a new fuse, such as Figures 1 to 9 The three-terminal fuse in this embodiment includes a substrate 1, on which are provided a first electrode J1, a second electrode J2, a third electrode J3, a first heating element H1, a second heating element H2, a flip plate 2, and a crossbar 3. The flip plate 2 is located between the crossbar 3 and the substrate 1.

[0045] The first and second electrodes J1 and J2 are two current control terminals, and the third electrode J3 is a voltage control terminal. That is, the first and second electrodes J1 and J2 are connected to the current path of the protected circuit, and the third electrode J3 triggers the voltage protection function based on the target voltage signal of the protected circuit.

[0046] The flip plate 2 is an overall arched structure, including an arched portion 20 and supporting legs 21 located at both ends of the arched portion 20 .

[0047] The crossbar 3 includes a fulcrum 30 and arms 31 at both ends of the fulcrum 30. The two arms 31 are each provided with a connection contact 32 for electrical connection. The two connection contacts 32 are electrically connected. In this embodiment, the two connection contacts 32 are preferably spherical structures.

[0048] The flip plate 2 includes an active layer C1 facing away from the crossbar 3 and a passive layer C2 facing the crossbar 3. The thermal expansion coefficient of the active layer C1 is greater than that of the passive layer C2, so that at the first target temperature, the flip plate 2 has a first state (such as Figure 3 and Figure 4 ), at the second target temperature, the flip plate 2 has a second state of arching back toward the crossbar 3 (such as Figure 5 and Figure 6 ).

[0049] By means of the flipping change of the flip plate 2 between the first state and the second state, the two legs 21 can drive the two arms 31 of the crossbar 3 to move up and down around the fulcrum 30, so that the two connection contacts 32 are respectively in contact with or separated from the first electrode J1 and the second electrode J2.

[0050] The first electric heating portion H1 can generate heat based on the current between the two connection contacts 32 , and a heat conduction channel is defined between the first electric heating portion H1 and the flip plate 2 .

[0051] The second electric heating portion H2 is located between the base plate 1 and the flip plate 2. In the first state, the two legs 21 abut against the second electric heating portion H2, and the arched portion 20 abuts against the fulcrum 30 of the crossbar 3. In the second state, the arched portion 20 abuts against the second electric heating portion H2, and the two legs 21 abut against the two arms 31 of the crossbar 3.

[0052] The second electric heating portion H2 is electrically connected to the third electrode J3 . The flip plate 2 is conductive, so that the second electric heating portion H2 is electrically connected to the connection contact 32 via the flip plate 2 .

[0053] The flip plate 2 also includes a shunting layer C3 located between the active layer C1 and the passive layer C2. The conductivity of the shunting layer C3 is much greater than that of the active layer C1 and the passive layer C2. It should be noted that as long as the conductivity of the shunting layer C3 is at least twice that of the active layer C1 and the passive layer C2, the conductivity of the shunting layer C3 is considered to be much greater than that of the active layer C1 and the passive layer C2.

[0054] In this embodiment, the first target temperature is room temperature, and the second target temperature is a warning temperature higher than room temperature. When the circuit where the fuse is located is in an abnormal state, the first electric heating part H1 or the second electric heating part H2 transfers the heat generated to the flip plate 2, causing the temperature of the flip plate 2 to rise above room temperature. When the temperature of the flip plate 2 reaches the warning temperature, due to the different thermal expansion coefficients on the two sides of the flip plate 2, the arched portion 20 of the flip plate 2 flips from one side facing the crossbar 3 to the other side, thereby driving the two arms 31 to move away from the base plate 1, as shown in FIG. Figure 5 , so that the connection contacts 32 on the two legs 21 are separated from the corresponding first electrode J1 and second electrode J2 to open the circuit.

[0055] When the circuit fault is eliminated, the heat transferred by the first electric heating part H1 and the second electric heating part H2 to the flip plate 2 returns to a normal level, causing the temperature of the flip plate 2 to drop. When the temperature of the flip plate 2 drops to room temperature, the flip plate 2 flips again. At this time, the two arms 31 of the crossbar 3 are reset under the action of the elastic restoring force, so that the two connecting contacts 32 are respectively in contact with the first electrode J1 and the second electrode J2, so that the circuit is connected again.

[0056] Therefore, the fuse with the above structure can be reused without the need for replacement, and after the abnormal state of the circuit is resolved, the fuse can automatically restore to a state that allows the circuit to be conductive.

[0057] In addition, for the active layer C1 and the passive layer C2 that can drive the flip plate 2 to flip, the conductivity is generally low. Therefore, by setting a high-conductivity shunt layer C3 in the middle of the flip plate 2, when the high-voltage fuse is triggered, the heating circuit of the second electric heating part H2 can be quickly connected, thereby improving the response speed of the three-terminal fuse and avoiding the flip plate 2 from being burned due to excessive current flowing through the flip plate 2.

[0058] On the other hand, the material of the active layer C1 includes any one of Mn-Ni-Cr-Cu alloy, Mn-Ni-Cu alloy, Ni-Cr-Fe alloy, Ni-Mn-Fe alloy and Cu-Zn alloy; the material of the passive layer C2 includes any one of Fe-Ni alloy and Fe-Ni-Mn alloy, and the diversion layer C3 includes any one of Cu-Ag alloy, Cu-Cd alloy, pure copper and pure nickel.

[0059] On the other hand, the thickness ratio α of the active layer C1 to the passive layer C2 satisfies: 1 / 2≤α≤2. Preferably, 5 / 6≤α≤1.2.

[0060] On the other hand, the overall thickness h1 of the flip plate 2 satisfies: 50 μm ≤ h1 ≤ 200 μm, preferably 60 μm ≤ h1 ≤ 120 μm, preferably 60 μm ≤ h1 ≤ 120 μm. The thickness h2 of the diversion layer C3 satisfies: 3 μm ≤ h2 ≤ 8 μm, preferably h2 = 5 μm.

[0061] On the other hand, the crossbar 3 is a conductive metal sheet with elasticity, and the two connection contacts 32 are electrically connected by means of the crossbar 3 , so there is no need to configure an additional connection harness for the two connection contacts 32 .

[0062] On the other hand, the crossbar 3 can generate heat due to its own resistance when current flows between the two connection contacts 32, so that the crossbar 3 functions as the first electric heating element H1. In this embodiment, the crossbar 3 itself serves as the electrical connection channel between the two connection contacts 32. At the same time, since the crossbar 3 has its own resistance, it will generate heat when current flows. Therefore, using the crossbar 3 as the first electric heating element H1 can further streamline the overall structure of the fuse.

[0063] On the other hand, the material of the crossbar 3 includes any one of a Cu-Ni-Si-Mg alloy and a Cu-Zr alloy. The thickness h3 of the crossbar 3 satisfies: 80 μm ≤ h3 ≤ 300 μm. Preferably, 100 μm ≤ h3 ≤ 200 μm.

[0064] On the other hand, in order to facilitate the connection of the fuse to the circuit, Figure 10 and Figure 11 The first electrode J1, the second electrode J2, and the third electrode J3 each include a first electrode sheet P1 disposed on the upper surface of the substrate 1 and a second electrode sheet P2 disposed on the lower surface of the substrate 1. Each pair of the first electrode sheet P1 and the second electrode sheet P2 is electrically connected via a third electrode sheet P3 that penetrates the upper and lower surfaces of the substrate 1. In this embodiment, each electrode (the first electrode J1, the second electrode J2, and the third electrode J3) is configured as a pair of the first electrode sheet P1 and the second electrode sheet P2, which are located on the upper and lower surfaces of the substrate 1, respectively. The first electrode sheet P1 is used to electrically connect various parts of the fuse, and the second electrode sheet P2 is used to electrically connect to the three ports of the circuit in which the fuse is located.

[0065] The above embodiment explains in detail the structural principle of the three-terminal fuse of the present invention. The working process of the fuse with the above structure is explained in detail below using a circuit for managing the charging and discharging of a pair of batteries.

[0066] like Figure 12In this charge and discharge management circuit, the fuse serves as a component of the secondary protection circuit. The first electrode J1 and the second electrode J2 of the fuse are respectively connected to the two ports K1 and K2 in the power loop of the charge and discharge management circuit, and the third electrode J3 is connected to the voltage control port K3 on the charge and discharge management circuit.

[0067] When the charge and discharge management circuit is operating normally, taking charging as an example, the flip plate 2 on the fuse is in the first state, so that the two connection contacts 32 on the arm 31 are in contact with the first electrode J1 and the second electrode J2 respectively. The charging current flows into the port K1 and flows out of the port K2. At this time, the circuit between the port K1 and the port K3 is not conductive.

[0068] When the charging current increases sharply and exceeds the safe value, the temperature of the crossbar 3 increases significantly under the action of the large current. The heat of the crossbar 3 is transferred to the flip plate 2 through the fulcrum 30. After the temperature of the flip plate 2 rises to the second target temperature, it flips over, causing the two legs 21 to separate from the second electric heating part H2 and tilt toward the crossbar 3, thereby lifting the two arms 31 and separating the two connection contacts 32 from the first electrode J1 and the second electrode J2. Figure 13 , then the connection between ports K1 and K2 in the charge and discharge management circuit is disconnected, thereby cutting off the circuit and protecting the circuit and terminal equipment. When the circuit fault is eliminated and the temperature on the flip plate 2 drops to the first target temperature, the flip plate 2 flips again, causing the two legs 21 to separate from the two arms 31 and re-engage with the second electric heating part H2. The two arms 31 reset under the action of the elastic restoring force, so that the two connection contacts 32 re-engage with the first electrode J1 and the second electrode J2, respectively, thereby connecting the ports in the circuit and restarting the circuit.

[0069] When the voltage detected by the overvoltage detection circuit in the charge-discharge management circuit suddenly increases and exceeds the safe value, the control switch connected to port K3 turns on, completing the circuit between ports K1 and K3. Current flows into port K1, then passes through the connecting contact 32, arm 31, fulcrum 30, arched portion 20, leg 21, second electric heating element H2, and third electrode J3, before flowing out of port K3. The current is transmitted between arched portion 20 and leg 21 on flip plate 2 through shunt layer C3. Then the second electric heating part H2 is energized and heated, and the heat generated is transferred to the flip plate 2, causing the temperature of the flip plate 2 to rise. When the temperature of the flip plate 2 rises to the second target temperature, it flips over, causing the two legs 21 to detach from the second electric heating part H2 and tilt toward the crossbar 3, thereby lifting the two arms 31, so that the two connection contacts 32 are separated from the first electrode J1 and the second electrode J2. Then the connection between port K1 and port K2 in the charge and discharge management circuit is disconnected, thereby cutting off the circuit and protecting the circuit and the terminal device. When the circuit fault is eliminated, the flip plate 2 flips over again, causing the two legs 21 to detach from the two arms 31 and re-contact the second electric heating part H2. The two arms 31 reset under the action of the elastic restoring force, so that the two connection contacts 32 re-contact the first electrode J1 and the second electrode J2 respectively, thereby connecting port K and port K in the circuit, and the circuit is restarted.

[0070] It should also be noted that when the ambient temperature rises abnormally, the flip plate 2 will also flip, thereby disconnecting the circuit and preventing the circuit from operating in abnormal ambient temperatures, effectively ensuring the safety of the circuit. When the ambient temperature drops back to the normal operating range, the flip plate 2 will move again to restart the circuit.

[0071] On the other hand, in order to facilitate the installation of fixed fuses, such as Figure 1 and Figure 2 The fuse in this embodiment further includes a mounting bracket 4 connected to the fulcrum 30 of the crossbar 3. The mounting bracket 4 is located on the side of the crossbar 3 facing away from the flip plate 2. Preferably, the mounting bracket 4 is provided with a slot 40, through which the fuse can be fixed to the relevant auxiliary fixing structure to facilitate assembly and disassembly.

[0072] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention are still within the scope of the present invention.

Claims

1. A self-recoverable three-terminal fuse, characterized in that: The invention comprises a substrate on which are provided a first electrode, a second electrode, a third electrode, a first electric heating portion, a second electric heating portion, a flip plate and a crossbar, which are separated from each other; the flip plate is located between the crossbar and the substrate; The first electrode and the second electrode are two current control terminals, and the third electrode is a voltage control terminal; The flip plate is an overall arched structure, comprising an arched portion and supporting legs located at both ends of the arched portion; The crossbar includes a fulcrum and support arms located at both ends of the fulcrum, and the two support arms are respectively provided with a connection contact for electrical connection, and the two connection contacts are electrically connected; The flip plate includes an active layer facing away from the crossbar and a passive layer facing the crossbar, wherein the active layer has a greater thermal expansion coefficient than the passive layer, so that at a first target temperature, the flip plate has a first state arched toward the crossbar, and at a second target temperature, the flip plate has a second state arched away from the crossbar; By means of the flipping change of the flip plate between the first state and the second state, the two legs can drive the two arms of the crossbar to move up and down with the fulcrum as the center, so that the two connection contacts are respectively in contact with or separated from the first electrode and the second electrode; The first electric heating part is capable of generating heat based on the current between the two connection contacts, and a heat conduction channel is provided between the first electric heating part and the flip plate; The second electric heating portion is located between the base plate and the flip plate, and in the first state, the two legs are in contact with the second electric heating portion; In the second state, the arched portion abuts against the second electric heating portion; The second electric heating portion is electrically connected to the third electrode, and the flip plate is conductive, so that the second electric heating portion is electrically connected to the connection contact by means of the flip plate; The flip plate further includes a shunt layer located between the active layer and the passive layer, and the conductivity of the shunt layer is much greater than that of the active layer and the passive layer.

2. The self-recoverable three-terminal fuse according to claim 1, characterized in that: The material of the active layer includes any one of Mn-Ni-Cr-Cu alloy, Mn-Ni-Cu alloy, Ni-Cr-Fe alloy, Ni-Mn-Fe alloy and Cu-Zn alloy; the material of the passive layer includes any one of Fe-Ni alloy and Fe-Ni-Mn alloy, and the diversion layer includes any one of Cu-Ag alloy, Cu-Cd alloy, pure copper and pure nickel.

3. The self-recoverable three-terminal fuse according to claim 1, characterized in that: The thickness ratio α of the active layer to the passive layer satisfies: 1 / 2≤α≤2.

4. The self-recoverable three-terminal fuse according to claim 1, characterized in that: The overall thickness h1 of the flip plate satisfies: 50 μm≤h1≤200 μm, and the thickness h2 of the diversion layer satisfies: 3 μm≤h2≤8 μm.

5. The self-recoverable three-terminal fuse according to claim 1, characterized in that: The crossbar is a conductive metal sheet with elasticity, and the two connection contacts are electrically connected by means of the crossbar.

6. The self-recoverable three-terminal fuse according to claim 5, characterized in that: The crossbar can generate heat due to its own resistance under the action of the current between the two connection contacts, so that the crossbar serves as the first electric heating part.

7. The self-recoverable three-terminal fuse according to claim 5, characterized in that: The material of the crossbar includes any one of Cu-Ni-Si-Mg alloy and Cu-Zr alloy.

8. The self-recoverable three-terminal fuse according to claim 5, characterized in that: The thickness h3 of the crossbar satisfies: 80 μm≤h3≤300 μm.

9. The self-recoverable three-terminal fuse according to claim 1, characterized in that: The first electrode, the second electrode and the third electrode each include a first electrode sheet arranged on the upper surface of the substrate and a second electrode sheet arranged on the lower surface of the substrate, and each pair of the first electrode sheet and the second electrode sheet are electrically connected through a third electrode sheet that passes through the upper and lower surfaces of the substrate.

10. The self-recoverable three-terminal fuse according to claim 1, characterized in that: The two connecting contacts are spherical structures.

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