A circuit protection device integrating the functions of an excitation fuse and a relay protection

Abstract

A circuit protection device integrating the functions of an excitation fuse and a relay protection, comprising a housing, a moving contact assembly, a moving contact transmission assembly, and a static contact assembly located in the housing, an excitation module detachably arranged in the housing, the excitation module including an excitation source and a power device; the fuse element passes through the arc extinguishing chamber and its two ends are respectively located on the housing on one side of different static contact assemblies; in the normal working state, the fuse element is in a non-conductive connection with the main circuit; when there is a zero fault current or a small fault current, the moving contact transmission assembly drives the moving contact to separate from the static contact assembly; when there is a large fault current, the moving contact transmission assembly is powered off, and at the same time, while the excitation source drives the power device to act, it drives the fuse element to be connected in parallel with the main circuit, and then drives the moving contact assembly to separate from the static contact assembly to disconnect the fuse element. The invention has a small volume and a compact structure, is applicable to the places where an excitation fuse and a relay are combined, and can save the use space.

Description

Technical Field

[0001] The present invention belongs to the fields of power control and electric vehicles, and more particularly to switching devices for power / electric vehicles. Background Art

[0002] Currently, the main protection devices for electric vehicle battery packs are traditional thermal fuses or current-limiting fuses used in combination with relays. A fuse is a protection device that uses the current heat accumulation effect to cause the current sensing point (neck) of the fuse element to melt and break within a certain time and extinguish the arc. A current-limiting fuse is a fast protection device that uses an electronic gas generating device to push an insulator to cut off a conductor to form a physical break within a short time. A relay is a repeatable protection device that connects or disconnects the main circuit conductor by controlling a small current.

[0003] Traditional fuses work by using the current heat accumulation effect. Therefore, its advantage is that in the case of a large multiple fault current, the fusing action will respond quickly; on the contrary, in the case of a small multiple fault current, the fusing action will be delayed. And due to its structure, a traditional fuse is a one-time device. The action characteristics of a relay are exactly complementary to the advantages and disadvantages of traditional fuses. The advantages of a relay are that in the case of a small multiple fault current, the action response is fast, the breaking efficiency is high, and within its breaking range, it can be broken and closed multiple times without affecting its working performance; the disadvantage is that its breaking upper limit is low. When the fault current is greater than its breaking upper limit, the moving and static contacts of the relay will be damaged during operation, affecting the working performance of the device. The advantage of a current-limiting fuse compared to a traditional fuse is that the breaking is actively controlled, and it can also perform fast breaking in the case of a small multiple fault current, but its product structure also determines that this device is a one-time protection device.

[0004] The circuit design and power transfer in an electric vehicle is a complex system. Low multiple fault current surges often occur in this system. This current surge is a challenge to the one-time action protection characteristics of current-limiting fuses and traditional fuses, and it is also a potential threat to the safe operation requirements of the main circuit. Combining the protection characteristics of a relay in the case of a small multiple fault current, when the relay and the current-limiting fuse are connected in series to the main circuit system, not only can the requirements of the system for the impact current resistance of the current-limiting fuse be reduced, but it is also an improvement and enhancement to the safety of the circuit system.

[0005] The advantage of the excitation fuse and relay protection scheme is that when there is a small - multiple fault current, the relay operates to disconnect the faulty circuit, and the excitation fuse does not operate; when there is a medium - large - multiple fault current, the excitation fuse actively operates to disconnect the fault current, and the relay does not operate. The disadvantage of this protection scheme is that to achieve the protection function for the same circuit, two components need to be arranged in the battery pack for protection, which is a great waste of the space inside the battery pack, and also increases the weight and cost of the battery pack.

[0006] How to integrate the relay and the excitation fuse together without mutual interference is a technical problem that urgently needs to be solved at present. Summary of the Invention

[0007] The object of the present invention is to provide a protection device with an integrated design of an excitation fuse and a relay. By redesigning the spatial structure of the relay, the main structure of the excitation fuse is arranged in the internal space of the relay, thereby integrating the functions of the two devices, greatly reducing the spatial size and weight of the device, and reducing the cost of the device.

[0008] To achieve the above object, the technical solution provided by the present invention is a circuit protection device integrating the protection functions of an excitation fuse and a relay, including a housing, a moving contact assembly, a moving contact drive assembly, and a static contact assembly located in the housing. It is characterized in that an excitation module is detachably arranged in the housing, and the excitation module includes an excitation source and a power device; the fuse element passes through the arc - extinguishing chamber filled with arc - extinguishing medium in the housing and its two ends are respectively arranged on the housing on one side of different static contact assemblies; in the normal working state, the fuse element is in a non - conductive connection with the main circuit; when there is a zero or small fault current, the moving contact drive assembly is powered off, and the moving contact is separated from the static contact assembly; when there is a large fault current, the moving contact drive assembly is powered off, and at the same time, the excitation source drives the power device to act according to the received excitation signal. After the fuse element is driven to be connected in parallel with the main circuit, the power device drives the moving contact assembly to be separated from the conductive connection with the static contact assembly, and then drives the moving contact assembly to disconnect the fuse element.

[0009] Preferably, after the excitation source drives the power device to push the moving contact assembly to be separated from the conductive connection with the static contact assembly according to the received excitation signal, the moving contact assembly disconnects the fuse element.

[0010] Preferably, a conduction device is also arranged in the housing, and the conduction device is connected to the cavity where the excitation source is located through an air duct; when the excitation source acts, it can drive the conduction device to connect the fuse element in parallel with the main circuit.

[0011] Preferably, a conductive elastic sheet is provided on the static contact, and the conduction device drives the conductive elastic sheet to be electrically connected to the end of the fuse wire, so that the fuse wire is connected in parallel with the main circuit.

[0012] Preferably, the excitation module includes an excitation housing in which a first cavity and a second cavity are formed; the excitation source and the power device are arranged in the first cavity, the conduction device is arranged in the second cavity, and the second cavity is communicated with the first cavity through an air duct; the excitation source can drive the power device and the conduction device to act simultaneously.

[0013] Preferably, the moving contact assembly includes a connecting rod connected to the moving contact transmission assembly, and the connecting rod disconnects the fuse wire.

[0014] Preferably, the arc extinguishing chamber includes a receiving groove provided in the housing, and an arc extinguishing chamber cover plate is detachably provided on the receiving groove.

[0015] Preferably, at least one fusing weak point is provided on the fuse wire, and the fusing weak point is located in the arc extinguishing chamber.

[0016] Preferably, at least one disconnection weak point is provided on the fuse wire, the disconnection weak point is located in the arc extinguishing chamber, and the fuse wire disconnects from the disconnection weak point.

[0017] Preferably, a positioning device for positioning the fuse wire is provided in the arc extinguishing chamber.

[0018] Preferably, the moving contact assembly is located in the housing between the arc extinguishing chamber and the static contact assembly; the arc extinguishing chamber and the static contact assembly define the displacement distance of the moving contact assembly.

[0019] The circuit protection device of the present invention organically integrates an excitation fuse and a relay. When there is a small fault current or zero fault current, the main circuit is conducted and disconnected by the electrical contact or disconnection of the static and moving contacts, so that the protection device can be reused; when there is a large fault current, the static and moving contacts are forced to be disconnected through the excitation module, and the fuse wire is disconnected to extinguish the arc in the arc extinguishing chamber. The circuit protection device of the present invention is small in size and compact in structure, can achieve breaking within the full current range, and the relay part can be reused. After the excitation module works, the circuit protection device can be reused by replacing the excitation module and the fuse wire. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the electrical contact structure of the static and moving contacts in the normal working state.

[0021] Figure 2It is a schematic structural diagram and a partial enlarged view A of the relationship between the conduction device, the conductive elastic sheet, and the fuse during normal operation or when the excitation source is not operating.

[0022] Figure 3 It is a schematic structural diagram of the separation structure of the moving and static contacts during a small current fault.

[0023] Figure 4 It is a schematic structural diagram when a large current fault occurs, the power device drives the moving contact to separate from the static contact, and the fuse is not disconnected.

[0024] Figure 5 It is a schematic structural diagram and a partial enlarged view A of the relationship between the excitation source and the power device when a large current fault occurs, and the conduction device connects the conductive elastic sheet and the fuse.

[0025] Figure 6 It is a schematic structural diagram when a large current fault occurs, the power device drives the moving contact to separate from the static contact, and the fuse melts.

[0026] Figure 7 It is a schematic structural diagram when a large current fault occurs, the power device drives the moving contact to separate from the static contact, and the fuse is disconnected by the moving contact transmission component. Specific embodiments

[0027] For the above technical solutions, preferred embodiments are given and described in detail in combination with the drawings. Refer to Figures 1 to 6 .

[0028] Refer to Figure 1 , which includes a housing 204. In the housing 204, there are mainly arranged a moving contact transmission component, a moving contact component, a static contact component, an excitation module, an arc extinguishing chamber 215, and a fuse 209, where:

[0029] The housing 204 is made of insulating material. The moving contact transmission component is a traditional relay moving contact transmission device, which is independently located in the bottom space of the housing 204. A separation support plate is arranged between the moving contact component and the moving contact transmission component to separate the moving contact component and the moving contact transmission component. The moving contact transmission component includes an excitation coil, a driving block 210 that drives linear displacement through the excitation coil. The driving block 210 is connected to the support plate through a spring. The driving block 210 can be displaced towards the static contact component under the magnetic force generated by the excitation coil and vertically compress the connected spring. There is a certain displacement gap between the initial position of the driving block 210 and the bottom of the housing 204.

[0030] The moving contact assembly includes a connecting rod 213, which is connected to a supporting plate by a spring. A moving contact 207 is provided on the supporting plate. The rod part of the connecting rod 213 passes through the supporting plate and is fixedly connected to a driving block 210. The connecting rod 213 is similar to a T-shaped structure. The end connected to the supporting plate has a large diameter end, and two step structures (213a, 213b) are designed on it. Among them, the step structure 213a near the driving block is used to limit the displacement distance of the connecting rod towards the bottom of the housing. The limit is achieved by clamping the step structure 213a on the supporting plate. The purpose of the step structure 213b is to disconnect the fuse 209.

[0031] The moving contact is made of conductive metal and has a certain stiffness and strength.

[0032] The static contact assembly includes at least two static contacts 206 arranged at intervals. A conductive elastic sheet 211 is electrically connected to the static contact 206, and the conductive elastic sheet extends out and is suspended on one side of the static contact 206. Wiring terminals 202 are respectively electrically connected to the static contacts 206. The wiring terminals 202 extend out of the housing 204 and can be connected to an external main circuit. The static contacts 206 are made of conductive metal, and the wiring terminals are also made of conductive metal.

[0033] When the excitation coil is energized, it drives the driving block 210 to move, driving the moving contact assembly to displace and make electrical contact with the static contact, thus connecting the main circuit.

[0034] At least one arc extinguishing chamber 215 is provided in the housing around the connecting rod 213. The arc extinguishing chamber includes an arc extinguishing housing 208, and the arc extinguishing housing 208 is sealed by a cover plate 214. An arc extinguishing medium is filled in the arc extinguishing chamber 215. The fuse 209 passes through the space between the connecting rod 213 and the driving block 210, passes through the arc extinguishing chamber 215, and then both ends of the fuse extend out of the arc extinguishing chamber and are arranged on the housing on one side of a static contact 206, and are directly below the conductive elastic sheet suspended on one side of the extended static contact. The fuse does not contact the static contact 206; when the fuse is electrically connected to the static contact through a conduction device 212, the fuse is connected in parallel with the main circuit. When the connecting rod displaces under the drive of the excitation coil, it will not affect the fuse structure. However, when the moving contact assembly is driven by the excitation module, the step structure 213b of the connecting rod will disconnect the fuse. The moving contact is located in the housing space between the static contact assembly and the arc extinguishing chamber, and the displacement distance of the moving contact is limited by the static contact and the arc extinguishing chamber.

[0035] At least one fusing weak point is provided on the melt located in the arc extinguishing chamber. The fusing weak point is a narrow neck, or a metallurgical effect point, or a combination of a narrow neck and a metallurgical effect point. A disconnection weak point is provided at the position where the connecting rod disconnects the melt to reduce the mechanical strength of the melt and facilitate the connecting rod to disconnect the melt. The disconnection weak point of the melt can be located in the arc extinguishing chamber or outside the arc extinguishing chamber. A positioning structure for positioning the melt is provided in the arc extinguishing chamber, such as a positioning post, so that the melt is threaded through the positioning post to achieve melt positioning. When the melt passes through the arc extinguishing chamber, it can pass out along the gap left between the arc extinguishing chamber and the cover plate for the melt to pass through.

[0036] An excitation module is fixedly arranged in a detachable manner in the housing between the static contacts. The excitation module includes an excitation housing 203. An excitation source 201, a power device 205 and a conduction device 504 are arranged in the excitation housing 203. A through first cavity 203a is formed in the excitation housing. The excitation source 201 and the power device 205 are arranged in the first cavity. The excitation source 201 is positioned by a limiting step in the first cavity of the excitation housing and a pressing plate (not shown) arranged outside the housing 204. The initial position of the power device 205 is defined by a limiting structure. The limiting structure can be a limiting bump arranged on the power device and a limiting groove arranged on the inner wall of the excitation housing. The limiting structure is formed by the limiting bump being stuck in the limiting groove. The power device 205 is in sealed contact with the excitation housing. The power device can also be in interference fit with the first cavity to realize the initial position limitation and at the same time realize the sealed contact. A certain gap is reserved between the power device 205 and the excitation source 201. The end face of the power device at one end of the excitation source is set as a concave surface. The excitation source 201 is a gas generating device that can release high-pressure gas to drive the power device to overcome the limiting structure and move. The power device 205 is located directly in front of the moving contact. The power device 205 is a piston block, and the end face on one side of the moving contact is a flat surface. When the moving contact is in conductive contact with the static contact and a large fault current occurs, the excitation source 201 receives an excitation signal to drive the power device to overcome the limiting structure and move. The power device displaces to the end face of the moving contact to drive the moving contact to displace and disconnect the conductive connection with the static contact. The contact surface between the power device and the moving contact is a flat surface, which can ensure that the force-bearing area of the moving contact is increased and no impact damage will be caused to the moving contact.

[0037] On the excitation housings on both sides of the power device, there is respectively provided a second cavity 203b with one end open. A conduction device 212 is arranged in the second cavity. The open end of the second cavity is located directly in front of the static contact conductive spring piece and the end of the fuse link. The conduction device 212 is in sealed contact with the second cavity. The conduction device 212 can have its initial position defined by a limiting structure. The conduction device 212 can also achieve sealed contact in the second cavity and at the same time define its initial position through interference fit. A gap is reserved between the conduction device and the bottom of the second cavity, and this gap is communicated with the gap between the power device and the excitation source in the first cavity through a flow channel. The distance between the conduction device 212 and the end of the fuse link is less than the distance between the power device and the moving contact that contacts the static contact.

[0038] During normal operation, the excitation coil is energized, and the moving contact makes conductive contact with the static contact under the magnetic force drive of the excitation coil, closing the main circuit. At this time, the fuse link is not connected to the static contact and the main circuit. A fault current threshold is set in the control system. When the fault current is small, the excitation coil is energized and de-energized to make the moving contact contact and separate from the static contact, controlling the opening and closing of the main circuit; when the fault current is large, when the excitation coil is de-energized, when the moving contact and the static contact separate, a large arc is generated at the break of the moving contact and the static contact, causing ablation damage to the moving contact and the static contact. Therefore, when the fault current is large, the control system sends an excitation signal to the excitation source, and at the same time controls the disconnection of the coil power supply circuit to de-energize the excitation coil. The excitation source acts to release high-pressure gas to drive the displacement of the power device. At the same time, the high-pressure gas released by the excitation source drives the displacement of the conduction device through the flow channel. The conduction device drives the static contact conductive spring piece to make conductive contact with the end of the fuse link, making the fuse link connected in parallel with the main circuit; subsequently, the power device drives the moving contact to separate from the static contact, and the reaction time is about 2 ms. Due to the existence of the parallel fuse link, when the moving contact separates from the static contact, about 70% of the fault current flows through the fuse link, and the current at the break of the moving contact and the static contact is very small, and the generated arc is very small or no arc is generated, which will not cause damage to the moving contact and the static contact; since the fault current flows through the fuse link, the fuse link melts at the weak melting point, disconnecting the main circuit, and the arc generated at the break of the fuse link is extinguished by the arc extinguishing medium. When the fuse link cannot melt in the first time, the moving contact assembly is displaced under the drive of the power device, and the connecting rod disconnects the fuse link from the weak melting point of the fuse link to cut off the main circuit. Since the weak melting point is located in the arc extinguishing medium, the break of the fuse link is extinguished by the arc extinguishing medium.

[0039] Since after the excitation coil is de-energized, it takes at least more than ten milliseconds for the moving contact and the static contact to separate. And the response time of the excitation module is about 2 ms. When the excitation coil is de-energized and cannot provide magnetic force support for the moving contact, the power device drives the moving contact to separate from the static contact without magnetic force blockage.

[0040] After the circuit is disconnected, during subsequent maintenance, it is only necessary to disassemble the device of the present invention and replace the fuse and the excitation module, and the components of the relay do not need to be replaced.

Claims

1. A circuit protection device integrating the functions of an excitation fuse and a relay protection, comprising a housing, a moving contact assembly, a moving contact transmission assembly, and a static contact assembly located in the housing, characterized in that, An excitation module detachably arranged in the housing, the excitation module including an excitation source and a power device; the moving contact assembly includes a connecting rod and a moving contact telescopically arranged on the connecting rod, the connecting rod being connected to the moving contact transmission assembly; an arc extinguishing chamber filled with an arc extinguishing medium is arranged on the outer periphery of the connecting rod, and both ends of the fuse wire are arranged on the housing on one side of different static contact assemblies after passing through the arc extinguishing chamber; in the normal working state, the fuse wire is in a non-conductive connection with the main circuit; when there is a zero fault current or a small fault current, the moving contact transmission assembly is powered off, and the moving contact is separated from the static contact assembly; when there is a large fault current, the moving contact transmission assembly is powered off, and at the same time, the excitation source acts according to the received excitation signal to release high-pressure gas as a driving force to drive the power device to act, and at the same time drive the fuse wire to be in conductive contact with the static contact assembly, so that after the fuse wire is connected in parallel with the main circuit formed by the static contact assembly and the moving contact assembly, the power device drives the moving contact assembly to be separated from the static contact assembly in a conductive manner, and then the power device drives the moving contact assembly to disconnect the fuse wire.

2. The circuit protection device according to claim 1, wherein, When the excitation source drives the power device to push the moving contact assembly to be separated from the static contact assembly in a conductive manner according to the received excitation signal, the moving contact assembly disconnects the fuse wire.

3. The circuit protection device according to claim 1, characterized in that, A conduction device is further arranged in the housing, and the conduction device is communicated with the cavity where the excitation source is located through an air passage; when the excitation source acts, it can drive the conduction device to connect the fuse wire in parallel with the main circuit.

4. The circuit protection device according to claim 3, characterized in that, A conductive elastic sheet is arranged on the static contact, and the conduction device drives the conductive elastic sheet to be in conductive connection with the end of the fuse wire, so that the fuse wire is connected in parallel with the main circuit.

5. The circuit protection device according to claim 3, wherein The excitation module includes an excitation housing, in which a first cavity and a second cavity are opened; the excitation source and the power device are arranged in the first cavity, the conduction device is arranged in the second cavity, and the second cavity is communicated with the first cavity through an air passage; the excitation source can drive the power device and the conduction device to act simultaneously.

6. The circuit protection device according to claim 2, wherein, The moving contact assembly includes a connecting rod connected to the moving contact transmission assembly, and the connecting rod disconnects the fuse wire.

7. The circuit protection device according to claim 1, characterized in that, The arc extinguishing chamber includes a receiving groove arranged in the housing, and an arc extinguishing chamber cover plate is detachably arranged on the receiving groove.

8. The circuit protection device according to claim 1, wherein At least one fusing weak point is arranged on the fuse wire, and the fusing weak point is located in the arc extinguishing chamber.

9. The circuit protection device according to claim 2, wherein, At least one breaking weak point is arranged on the fuse wire, the breaking weak point is located in the arc extinguishing chamber, and the fuse wire breaks from the breaking weak point.

10. The circuit protection device according to claim 2, wherein A positioning device for positioning the fuse wire is arranged in the arc extinguishing chamber.

11. The circuit protection device according to claim 1, characterized in that, The moving contact assembly is located in the housing between the arc extinguishing chamber and the static contact assembly; the arc extinguishing chamber and the static contact assembly define the displacement distance of the moving contact assembly.

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