Self-recovery three-terminal protector

Abstract

The invention discloses a self-recovery three-terminal protector which comprises a substrate, and the substrate is provided with a first electrode, a second electrode, a third electrode, a first electric heating part, a second electric heating part, an overturning plate and a cross rod. The whole turnover plate is of an arch structure and comprises an arching part and supporting legs located at the two ends of the arching part. The transverse rod comprises a supporting point and supporting arms located at the two ends of the supporting point, the two supporting arms are each provided with a connecting contact used for electric connection, the overturning plate comprises an active layer back on to the transverse rod and a passive layer facing the transverse rod, and the overturning plate has a first state of arching towards the transverse rod and a second state of arching towards the transverse rod; the flip plate further comprises a shunt layer located between the active layer and the passive layer, and the conductivity of the shunt layer is much larger than that of the active layer and the passive layer. According to the three-terminal protector, the repeated use of the three-terminal protector can be realized through the overturning movement of the overturning plate based on the temperature; in addition, the high-conductivity shunting layer is arranged in the middle of the turnover plate, so that the response speed of the three-terminal protector is effectively improved.

Description

Technical Field

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

[0002] The three-terminal fuse has both overcurrent and overvoltage protection functions and is widely used in many fields such as battery management systems. It is an important circuit protection component. The three-terminal fuses commonly used at present mostly cut off the circuit by melting the built-in alloy fuse under high temperature conditions. They are disposable electronic products. After the circuit fault is eliminated, a new fuse needs to be replaced, which increases additional manual operations and economic costs, and also causes waste of resources. Summary of the invention

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

[0004] In order to achieve the above-mentioned object, the present invention provides a self-recoverable three-terminal fuse, which includes a substrate, on which a first electrode, a second electrode, a third electrode, a first electric heating portion, a second electric heating portion, a flip plate and a cross bar are provided, which are separated from each other; the flip plate is located between the cross bar 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, including an arched portion and legs located at both ends of the arched portion;

[0007] The crossbar includes a fulcrum and support arms 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 of arching toward the crossbar, and at a second target temperature, the flip plate has a second state of arching 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 can generate heat based on the current between the two connecting contacts, and a heat conduction channel is provided between the first electric heating part and the flip plate;

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

[0012] The second electric heating part is electrically connected to the third electrode, and the flip plate is conductive, so that the second electric heating part 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 connecting 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, when a circuit fails, the first electric heating part or the second electric heating part transfers excessive heat to the flip plate, and the flip plate moves to disconnect the circuit. When the circuit fault is eliminated, the temperature of the flip plate drops and it flips again, thereby driving the circuit to re-enter the connected state, so as to realize the reuse of the three-terminal fuse without the need for replacement in the middle.

[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 It is a three-dimensional structural diagram of a three-terminal fuse in one embodiment of the present invention.

[0026] Figure 2 for Figure 1 Side view of.

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

[0028] Figure 4 for Figure 3 Side view of.

[0029] Figure 5 It is a three-dimensional 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 of.

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

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

[0033] Fig. 9 for Figure 8 Side view of.

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

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

[0036] Fig.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] Fig.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] Fig.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 implementation methods 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 working mechanism of the traditional three-terminal fuse is first described below.

[0041] like Fig.14 The traditional three-terminal fuse includes three terminals, two fuses made of alloy metal and a heating wire. The fuse can be melted in the event of overcurrent or short circuit fault, cutting off the circuit to protect it. The three terminals are two first terminals for current control and one second terminal for voltage control. The two fuses are connected in series between the two first terminals.

[0042] Taking the battery charging and discharging circuit as an example, when the charging current is too large, the fuse between the two first terminals will blow directly. After overcharging, the voltage is too high, and the controller will give a low level to the second terminal, then the circuit where the heating wire is located will be turned on, and the heating wire will start to heat up and blow the fuse. Thus, overcurrent and overvoltage protection is achieved.

[0043] It can be seen 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 disposed a first electrode J1, a second electrode J2, a third electrode J3, a first electric heating portion H1, a second electric heating portion H2, a flip plate 2 and a crossbar 3, which are separated from each other. The flip plate 2 is located between the crossbar 3 and the substrate 1.

[0045] The first electrode J1 and the second electrode J2 are two current control terminals, and the third electrode J3 is a voltage control terminal. That is, the first electrode J1 and the second electrode 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 two 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 respectively provided with a connection contact 32 for electrical connection, and 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 being arched away from the cross bar 3 (eg 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 connecting contacts 32 are respectively in contact with or separated from the first electrode J1 and the second electrode J2.

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

[0051] The second electric heating part 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 part H2, and the arched part 20 abuts against the fulcrum 30 of the crossbar 3. In the second state, the arched part 20 abuts against the second electric heating part H2, and the two legs 21 abut against the two arms 31 of the crossbar 3 respectively.

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

[0053] The flip plate 2 also includes a shunt layer C3 located between the active layer C1 and the passive layer C2, and the conductivity of the shunt 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 shunt layer C3 is more than twice that of the active layer C1 and the passive layer C2, it can be considered that the conductivity of the shunt layer C3 is 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 generated heat to the flip plate 2, so that the temperature of the flip plate 2 rises above room temperature. When the temperature of the flip plate 2 reaches the warning temperature, due to the different thermal expansion coefficients of the two sides of the flip plate 2, the arched part 20 of the flip plate 2 flips from one side facing the cross bar 3 to the other side, thereby driving the two arms 31 to move away from the substrate 1, such as 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 cross bar 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 replacement, and after the abnormal state of the circuit is eliminated, the fuse can automatically restore to a state that makes the circuit 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 and 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 diverter 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 under the action of the current between the two connection contacts 32 based on its own resistance, so that the crossbar 3 is used as the first electric heating part H1. In this embodiment, the crossbar 3 itself serves as an electrical connection channel between the two connection contacts 32. At the same time, since the crossbar 3 itself has resistance, it will generate heat under the action of the current. Therefore, the crossbar 3 is also used as the first electric heating part H1, which can make the overall structure of the fuse more streamlined.

[0063] On the other hand, the material of the crossbar 3 includes any one of Cu-Ni-Si-Mg alloy and 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, Fig.10 and Fig.11 The first electrode J1, the second electrode J2 and the third electrode J3 all 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, and each pair of the first electrode sheet P1 and the second electrode sheet P2 is electrically connected through the third electrode sheet P3 that penetrates the upper surface and the lower surface 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 on the upper surface and the lower surface of the substrate 1, respectively. The first electrode sheet P1 is used for electrical connection of various parts inside the fuse, and the second electrode sheet P2 is used for electrical connection with the three ports of the circuit where the fuse is located.

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

[0066] like Fig.12In the charge and discharge management circuit, the fuse is used as a device 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 works normally, taking charging as an example, the flip plate 2 on the fuse is in the first state, so that the two connecting contacts 32 on the arm 31 are in contact with the first electrode J1 and the second electrode J2 respectively, and 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 safety 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, so that the two legs 21 are separated from the second electric heating part H2 and tilted 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, as shown in FIG. Fig.13 , then the connection between port K1 and port K2 in the charge and discharge management circuit is disconnected, thereby cutting off the circuit, which plays a role in protecting the circuit and the terminal device. 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, so that the two legs 21 are separated from the two arms 31 and re-contact the second electric heating part H2. The two arms 31 are reset under the action of elastic restoring force, so that the two connection contacts 32 are re-contacted 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 and discharge management circuit suddenly increases and exceeds the safety value, the control switch connected to the port K3 is turned on, so that the circuit between the port K1 and the port K3 is turned on, and the current flows in from the port K1, and then passes through the connection contact 32, the arm 31, the fulcrum 30, the arched portion 20, the leg 21, the second electric heating portion H2, the third electrode J3, and then flows out from the port K3. Among them, the current is transmitted between the arched portion 20 and the leg 21 on the flip plate 2 through the shunt layer C3. Then the second electric heating part H2 is powered on to generate heat, and the generated heat is transferred to the flip plate 2, so that the temperature of the flip plate 2 rises. When the temperature of the flip plate 2 rises to the second target temperature, it flips over, so that the two legs 21 are separated from the second electric heating part H2 and tilted 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, and then the connection between the port K1 and the port K2 in the charge and discharge management circuit is disconnected, thereby cutting off the circuit, playing a role in protecting the circuit and the terminal device. When the circuit fault is eliminated, the flip plate 2 flips over again, so that the two legs 21 are separated from the two arms 31, and re-contact with the second electric heating part H2, and the two arms 31 are reset under the action of the elastic restoring force, so that the two connection contacts 32 are re-contacted with the first electrode J1 and the second electrode J2 respectively, thereby connecting the ports K and 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 to cut off the circuit, preventing the circuit from working under abnormal ambient temperature, which can effectively ensure the safety performance of the circuit. When the ambient temperature drops to the normal working 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 frame 4, which is connected to the fulcrum 30 of the crossbar 3 and is located on the side of the crossbar 3 facing away from the flip plate 2. Preferably, a card slot 40 is provided on the mounting frame 4, through which the fuse can be fixed on the relevant auxiliary fixing structure to facilitate disassembly and assembly.

[0072] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights 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 covered by the present invention.

Claims

1. A self-recoverable three-terminal fuse, characterized in that: The invention comprises a substrate, on which are arranged a first electrode, a second electrode, a third electrode, a first electric heating part, a second electric heating part, a flip plate and a cross bar which are separated from each other; the flip plate is located between the cross bar 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, including an arched portion and legs located at both ends of the arched portion; The crossbar includes a fulcrum and support arms 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 of arching toward the crossbar, and at a second target temperature, the flip plate has a second state of arching 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 can generate heat based on the current between the two connecting contacts, and a heat conduction channel is provided between the first electric heating part and the flip plate; The second electric heating part 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 part; In the second state, the arched portion abuts against the second electric heating portion; The second electric heating part is electrically connected to the third electrode, and the flip plate is conductive, so that the second electric heating part 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 shunt 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: A 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 connecting 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 is 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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