Excitation fuse capable of breaking melt in delayed manner

Abstract

The excitation fuse comprises an electronic ignition device, a piston, a conductive busbar, a limiting column structure, a fuse structure and a melt cutter. The piston comprises a first moving part and a second moving part which can move relatively, and the second moving part is located in the first moving part. The first moving part is used for cutting off the conductive busbar; an airflow channel is formed in the second moving part and can be communicated with a cavity where the high-pressure gas release end of the electronic ignition device is located and a cavity where the melt cutter is located; relative displacement of the first moving part and the second moving part is realized through the limiting column structure; through synchronous displacement and relative displacement of the first moving part and the second moving part, connection and disconnection of the airflow channel are realized, so that delayed disconnection of the melt after the conductive busbar is disconnected is realized. According to the invention, the structure is relatively simple, the arc pressure of melt disconnection is reduced through delay disconnection of the melt, and the breaking capacity and the insulation performance after disconnection are improved.

Description

Technical Field

[0001] The present invention relates to the fields of electric vehicles, power control, motor protection, etc., and in particular to an excitation fuse that delays the melting time of the melt through a pressure reduction and exhaust structure. Background Art

[0002] An excitation fuse is triggered to operate by a control signal to implement circuit protection. It has the characteristics of small volume, resistance to strong current impact, fast action speed, etc. It can not only play a protective role in circuit short - circuit and severe overload, but also quickly and reliably cut off the current loop in scenarios such as vehicle collision and wading to protect the safety of the vehicle electrical system; relying on a fault current detection device, it can avoid misoperation during normal overload, such as fast charging of electric vehicles and rapid acceleration of vehicles, and can ensure that the current is quickly cut off when a real fault occurs.

[0003] At present, excitation fuses already exist in the market and their application fields are gradually expanding. The general structural composition is as Figure 1 shown: an electronic ignition device 101, a first housing 102, a sealing ring 103, a piston 104, a conductive bus bar 105, a melt 106, a lower housing 107, a melt protection housing 108, a melt cutter 109, and an arc extinguishing medium 110. The electronic ignition device 101 can act according to the received trigger signal and release high - pressure gas as a driving force, which can be a gas generating device.

[0004] The working principle is as follows: The excitation fuse is connected in series in the circuit. In the normal working state, the current flows through the conductive bus bar 105, and the excitation fuse can be regarded as a current - carrying conductor. When the vehicle is in an abnormal working state and needs to cut off the circuit, the vehicle sends a signal to trigger the electronic ignition device 101 to generate high - pressure gas. First, it pushes the piston 104 to move and cut the weak part of the conductive bus bar 105 to form an air break, and then pushes the melt cutter 109 to cut the melt 106 to achieve complete electrical isolation. When the fault current is small, the heat generated at the narrow neck of the melt 106 is not enough to fuse it, and the melt cutter 109 is relied on to cut the melt 106. The arc generated during the cutting process is eliminated and extinguished in the arc extinguishing medium 110; when the fault current is large, the heat generated at the narrow neck of the melt 106 causes the melt 106 to quickly fuse and cut off the current. At this time, the generated arc, along with the action of the melt cutter 109 on the melt 106, the arc at the break of the melt 106 is stretched until it extinguishes. By relying on the piston 104 acting on the conductive bus bar 105 and the melt cutter 109 acting on the melt 106 respectively, a physical isolation break is achieved to ensure the electrical insulation requirements.

[0005] Although the breaking control of this excitation fuse has been improved compared with that of the thermal fuse, there are still the following deficiencies:

[0006] The piston quickly cuts off the conductive busbar. At this time, the melt conducts current and limits the current. When the melt fails to fully limit the current, the melt cutter quickly cuts off the melt. At this time, the melt cutter operates when the current is relatively large, resulting in a rapid increase in the arc pressure at the melt fracture, making it difficult to interrupt or resulting in poor insulation after interruption, and it is difficult to increase the breaking limit of the product. When the arc pressure generated when the melt breaks is large, higher requirements are imposed on the wall thickness and material of the housing, leading to an increase in product cost. Moreover, to prevent the leakage of high-pressure gas and arc, higher requirements are imposed on the product structure and sealing performance, increasing the design difficulty and processing cost. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a novel incentive fuse structure for delaying the disconnection of the melt. The piston is divided into two independent moving parts, and an air flow channel is arranged on one moving part. By the synchronous displacement and relative displacement of the two moving parts of the piston, the time when the air flow channel communicates with the chamber where the electronic ignition device is located is delayed, so as to realize the delayed disconnection of the melt. After the effective current limiting of the melt is achieved, the melt is disconnected, the arc pressure is reduced, the breaking voltage and breaking current are increased, and the insulation performance after interruption of the product is also improved.

[0008] To solve the above technical problems, the technical solution provided by the present invention is an incentive fuse for delaying the disconnection of the melt, including an electronic ignition device, a piston, a conductive busbar, a limit post structure, and a fuse structure; the fuse structure includes a fuse housing, an arc extinguishing medium filled in the fuse housing, and a melt passing through the arc extinguishing medium, and both ends of the melt extend out of the fuse housing;

[0009] The electronic ignition device and the piston are arranged on one side of the conductive busbar, the fuse structure is located on the other side of the conductive busbar, and the melt is connected in parallel with the conductive busbar; the electronic ignition device operates according to the received trigger signal and can drive the piston to displace and cut off the conductive busbar;

[0010] A displacement channel is arranged on the fuse structure along the displacement direction of the piston. At least one end of the displacement channel penetrates one end of the fuse structure where it is located. A melt cutter is arranged in the displacement channel, and the melt passes through the displacement channel and is located on the displacement path of the melt cutter; the piston includes a first moving part and a second moving part that can displace relative to each other. A receiving through hole that penetrates both ends along its displacement direction is opened in the first moving part, and the second moving part is located in the receiving through hole of the first moving part;

[0011] The second moving part includes a limiting part and a column body part in the shape of a column which are integrally connected. The outer diameter of the column body part is smaller than that of the limiting part. On the outer side surface of the column body part of the second moving part, air flow guiding ribs protruding from the outer side surface of the column body part are arranged along the length direction of the column body part. At least two such air flow guiding ribs are distributed at intervals along the circumferential direction of the column body part, and an air flow channel is formed between two adjacent air flow guiding ribs; alternatively, on the outer side surface of the column body part, at least one long strip-shaped air duct guiding groove penetrating through one end of the column body part towards the fuse structure direction is arranged along the length direction of the column body part, and the air duct guiding groove forms the air flow channel.

[0012] In the initial position, the limiting part of the second moving part closes one end of the accommodating through hole of the first moving part facing the electronic ignition device and the air flow channel.

[0013] The limiting column structure is fixedly arranged on the displacement path of the second moving part and is used to prevent the displacement of the second moving part, so that relative displacement occurs between the first moving part and the second moving part, and the air flow channel is conducted. The conducted air flow channel enables the cavity where one end of the melt cutter or the fuse structure facing the conductive busbar is located to communicate with the cavity where one end of the driving force release of the electronic ignition device is located.

[0014] When an overload, short-circuit current or abnormal condition occurs in the electrical circuit where the excitation fuse is located, the electronic ignition device acts according to the received trigger signal to release high-pressure gas, driving the first moving part and the second moving part to displace synchronously. After the first moving part cuts off the conductive busbar, the limiting column structure prevents the second moving part from displacing, and the first moving part displaces relative to the second moving part, and the air flow channel is conducted; the high-pressure gas released by the electronic ignition device flows through the air flow channel, driving the melt cutter to displace to cut off the melt, or driving the fuse structure to displace, so that the melt cutter cuts off the melt.

[0015] Preferably, at least several air flow guiding ribs or several air duct guiding grooves are evenly distributed at intervals along the circumferential direction of the column body part, and the evenly distributed air flow channels are formed in the circumferential direction of the column body part.

[0016] Preferably, an air flow channel for the high-pressure gas to pass through is also provided in the second moving part. One end opening of the air flow channel is located on the outer side surface of the limiting part, and the other end opening is located on the end surface of the column body part facing the limiting column structure. When the limiting part closes one end of the accommodating through hole of the first moving part facing the electronic ignition device, the air flow channel is also closed simultaneously.

[0017] Preferably, a limiting step is provided in the accommodation through-hole of the first moving part facing the direction of the electronic ignition device; the limiting part of the second moving part is arranged on the limiting step.

[0018] Preferably, the end face of the column body part of the second moving part facing the direction of the conductive busbar is arranged close to the impact end of the first moving part, or close to the limiting step in the first moving part.

[0019] Preferably, when driving the melt cutter to displace and cut off the melt, the fuse structure is fixedly arranged, a buffer structure is arranged between the melt cutter and the conductive busbar, and the cavity where the end face of the buffer structure facing the conductive busbar is located can be communicated with the cavity where the high-pressure gas release end of the electronic ignition device is located through the air flow channel; the melt cutter protrudes from the displacement channel towards the buffer structure, and the melt cutter supports the buffer structure; the melt cutter is one group or at least two groups or more, and one group of melt cutters is arranged corresponding to one group of displacement channels. When there are two or more groups of melt cutters, the lengths of the melt cutters protruding from the displacement channel are the same or different; the high-pressure gas can drive the buffer structure to displace through the air flow channel, and the displacement of the buffer structure drives the melt cutter to displace and cut off the melt. When there are two or more groups of melt cutters, the melt cutters cut off the melt simultaneously or successively.

[0020] Preferably, the limiting column structure is fixedly arranged on one side of the end face of the buffer structure facing the conductive busbar. A through-hole penetrating through both ends is arranged in the limiting column structure. When the second moving part contacts the limiting column structure, the air flow channel is communicated with the through-hole of the limiting column structure, so that the cavity where one end of the buffer structure facing the conductive busbar is located is communicated with the cavity where the driving force release end of the electronic ignition device is located, and the high-pressure gas can drive the buffer structure to displace through the air flow channel and the through-hole of the limiting column structure.

[0021] Preferably, it further includes a first housing, a second housing, and a bottom protection cover that are sequentially spliced. A receiving groove is provided at one end of the second housing facing the direction of the conductive busbar and at the other end of the second housing facing the direction of the bottom protection cover. The electronic ignition device and the piston are sequentially arranged in the first housing, and the conductive busbar is arranged between the first housing and the second housing. The buffer structure and the fuse structure are located in the cavity formed between the receiving groove of the second housing and the bottom protection cover. The limiting column structure protrudes from the bottom of the receiving groove of the second housing facing the direction of the conductive busbar, and a through hole penetrating the limiting column structure and the second housing is provided on the limiting column structure, and the receiving grooves at both ends of the second housing are communicated through the through hole. The buffer structure is nested on the bottom of the receiving groove of the second housing facing the direction of the bottom protection cover, and the nested part of the buffer structure surrounds the open end of the through hole of the limiting column structure. The fuse structure is supported by the bottom protection cover. When the limiting column structure contacts the second moving part, the air flow channel on the second moving part is communicated with the through hole of the limiting column structure.

[0022] Preferably, the limiting column structure protrudes and is fixedly arranged on the end face of the fuse structure facing the conductive busbar. The limiting column structure is located on one side of the end face of the buffer structure facing the direction of the bottom protection cover, and the limiting column structure penetrates through the buffer structure.

[0023] Preferably, a blocking structure is arranged between the buffer structure and the conductive busbar. The blocking structure is located on the displacement path of the piston. Through holes for the limiting column structure to pass through are respectively provided on the part of the conductive busbar to be disconnected and the blocking structure. The blocking structure blocks the displacement speed of the first moving part after disconnecting the conductive busbar. After the first moving part disconnects the conductive busbar, it can drive the blocking structure to displace synchronously with the first moving part. The limiting column structure passes through the blocking structure and the disconnected part of the conductive busbar. The limiting column structure prevents the second moving part from displacing. A gap for gas to flow through is reserved between the through hole on the blocking structure and the limiting column structure. The first moving part continues to drive the blocking structure and the disconnected part of the conductive busbar to displace to the end position, so that the first moving part and the second moving part displace relatively, the air flow channel is conducted, and the high-pressure gas drives the buffer structure to displace through the air flow channel and the gap between the limiting column structure and the blocking structure.

[0024] Preferably, it further includes an upper cover, a first housing, a second housing, and a bottom protection cover that are sequentially spliced; the electronic ignition device is arranged on the upper cover, the piston is arranged in the first housing, the conductive busbar is arranged between the first housing and the second housing, and the buffer structure and the fuse structure are arranged in the second housing; a guiding boss is convexly arranged in the second housing in the direction towards the bottom protection cover, and a through hole penetrating the guiding boss and one end of the second housing towards the conductive busbar is arranged on the guiding boss; the blocking structure is arranged in the through hole of the guiding boss in a tightly fitting manner; the buffer structure is nested on the outer periphery of one end of the guiding boss in the direction towards the bottom protection cover; the limiting column structure is convexly arranged on the end face of the fuse structure in the direction towards the buffer structure; limiting bosses are respectively arranged on the relative two sides of the through hole of the blocking structure corresponding to the disconnected part of the conductive busbar; when the first moving part disconnects the conductive busbar, the first moving part drives the disconnected part of the conductive busbar and the second moving part to displace synchronously until the air flow channel is communicated with the chamber where the end face of the buffer structure facing the conductive busbar is located.

[0025] Preferably, the blocking structure includes a hollow supporting end face and a blocking structure main body, the through hole is arranged on the blocking structure main body, the supporting end face is integrally connected in the through hole, and the connection between the supporting end face and the through hole is a weak disconnection part; in the initial position, one end of the limiting column structure facing the conductive busbar supports at the supporting end face; when the blocking structure is driven by the first moving part, the limiting column structure disconnects the supporting end face from the weak disconnection part connected to the through hole, and the limiting column structure drives the supporting end face to pass through the through hole on the blocking structure main body to contact the second moving part.

[0026] Preferably, an air flow buffer chamber is arranged on the buffer structure, and when the first moving part and the second moving part displace relatively and the air flow channel is conducted, the air flow buffer chamber of the buffer structure is communicated with the air flow channel.

[0027] Preferably, when driving the displacement of the fuse structure, the melt part located between the fuse structure and the conductive busbar is bent; one end of the limit post structure is fixedly arranged between the fuse structure and the conductive busbar; the end of the melt cutter away from the conductive busbar protrudes from the displacement channel; the melt cutter is one group or at least two groups or more, and one group of melt cutters corresponds to one group of displacement channels. When there are two or more groups of melt cutters, the lengths of the melt cutters protruding from the displacement channel are the same or different; when the fuse structure is displaced, the melt cutter reaches the termination position first, and the fuse structure reaches the termination position later. A relative displacement occurs between the fuse structure and the melt cutter, so that the melt cutter cuts off the melt simultaneously or successively.

[0028] Preferably, it further includes an upper cover, a first housing, a second housing, and a bottom protection cover that are spliced in sequence; the electronic ignition device is arranged on the upper cover, the piston is arranged in the first housing, the conductive busbar passes through between the first housing and the second housing, both ends of the second housing are through, the fuse structure is located in the second housing and there is a displacement distance for the displacement of the fuse structure reserved between the fuse structure and the bottom protection cover; a guiding cover plate for closing the end of the second housing is arranged at one end of the second housing facing the conductive busbar; a receiving groove facing the part of the conductive busbar to be disconnected is opened on the end face of the guiding cover plate facing the conductive busbar, and the limit post structure is arranged at the bottom of the receiving groove facing the second moving part, and one end of the limit post structure facing the piston passes through the conductive busbar and is located in the first housing; a through hole penetrating the limit post structure and the guiding cover plate is opened on the limit post structure, and the cavities where both ends of the guiding cover plate are located are communicated through the through hole on the limit post structure; limit bosses for receiving the disconnected part of the conductive busbar are respectively arranged at the bottom of the receiving groove on the relative two sides of the limit post structure corresponding to the part of the conductive busbar to be disconnected; the fuse structure is located between the guiding cover plate and the bottom protection cover, and blocks the communication between the cavity where the bottom protection cover is located and the conductive cavity where the guiding cover plate is located; the melt cutter protrudes from the displacement channel in the direction of the bottom protection cover;

[0029] When the piston is displaced, the first moving part and the second moving part are displaced synchronously until the first moving part cuts off the conductive busbar, and then the second moving part contacts the limiting column structure to stop displacement, and the first moving part is displaced relative to the second moving part until the first moving part drives the disconnected part of the conductive busbar to the limiting boss of the conductive cover plate; when the first moving part and the second moving part are relatively displaced, the airflow channel is connected, and the high-pressure gas enters the cavity where one end of the fuse structure is located toward the conductive cover plate through the airflow channel and the through hole of the limiting column structure, driving the fuse structure to displace, so that the melt cutter contacts the bottom protective cover first, and then the fuse structure contacts the bottom protective cover, so that the melt cutter disconnects the melt.

[0030] Preferably, a guide boss is provided at one end of the second shell facing the conductive busbar, the guide boss protrudes toward the fuse structure, and a through hole is provided on the guide boss that penetrates the guide boss and allows the piston and the disconnected part of the conductive busbar to move; the guide cover is nested at one end of the guide boss facing the fuse structure, and the limiting column structure and the limiting boss on the guide cover are located in the through hole of the guide boss.

[0031] Preferably, an insulating cushion is provided between the second shell and the bottom protective cover, and the insulating cushion is provided in close contact with the bottom protective cover.

[0032] The excitation fuse of the delayed disconnection fuse of the present invention controls the disconnection or connection of the airflow channel arranged on the second moving part with the cavity where the high-pressure gas release end of the electronic ignition device is located through the synchronous displacement and relative displacement of the first moving part and the second moving part of the piston, delays the disconnection of the fuse, makes the fuse fully and effectively limit the current before disconnection, reduces the arc pressure when the fuse is disconnected, and improves the breaking capacity.

[0033] By adding a buffer structure and setting a groove in the buffer structure to form an airflow buffer chamber, the volume of the cavity where the pressure gas is located is increased, so that the gas pressure is reduced, thereby reducing the applied driving force and the displacement speed, thereby further delaying the melt disconnection time.

[0034] By adding a blocking structure to block the first moving part, reducing the displacement speed of the first moving part, prolonging the exposure time of the airflow channel, and combining the airflow buffer chamber of the buffer structure, the melt disconnection time is further prolonged.

[0035] By increasing the groove structure of the fuse cover, the volume of the chamber where the pressure gas is located is increased, so that the gas pressure is reduced, thereby reducing the applied driving force and the displacement speed, thereby further delaying the fuse disconnection time.

[0036] By means of the displacement distance of the fuse structure and the displacement distance of the melt cutter, the time for disconnecting the melt is further prolonged.

[0037] The excitation fuse structure of the present invention prolongs the melt disconnection time, reduces the arc pressure when the melt is disconnected, thereby reducing the requirements for the wall thickness and material of the housing and reducing the production cost; after pressure reduction, the high-pressure gas becomes medium-pressure gas and low-pressure gas, which can reduce the requirements for the product structure and sealing performance, reduce the design difficulty and processing difficulty of the column, and thus reduce the processing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a schematic diagram of the existing excitation fuse structure.

[0039] Figure 2 is a schematic diagram of the excitation fuse structure of Embodiment 1 (at the initial position).

[0040] Figure 3 is a schematic diagram of the structure when the conductive busbar of Embodiment 1 is disconnected.

[0041] Figure 4 is a schematic diagram of the structure when the second moving part of the piston contacts the limit boss after the conductive busbar of Embodiment 1 is disconnected.

[0042] Figure 5 is a schematic diagram of the structure when the first moving part of the piston moves to the end position after the conductive busbar of Embodiment 1 is disconnected.

[0043] Figure 6 is a schematic diagram of the structure when the melt of Embodiment 1 is disconnected.

[0044] Figure 7 is a schematic diagram of the excitation fuse structure of Embodiment 2 (at the initial position).

[0045] Figure 8 is a schematic diagram of the structure when the second moving part of the piston contacts the limit post after the conductive busbar of Embodiment 2 is disconnected.

[0046] Figure 9 is a schematic diagram of the structure when the first moving part of the piston moves to the end position and the long melt cutter disconnects the melt after the conductive busbar of Embodiment 2 is disconnected.

[0047] Figure 10 is a schematic diagram of the structure when the long melt cutter moves to the end position and the short melt cutter disconnects the melt in Embodiment 2.

[0048] Figure 11 is a schematic diagram of the external structure of Embodiment 2.

[0049] Figure 12 is Figure 11Schematic diagram of the three-dimensional partial sectional structure

[0050] Figure 13 Schematic diagram of the structure of the second moving part of the piston in Embodiment 2

[0051] Figure 14 Schematic diagram of the structure of the buffer bushing in Embodiment 2, where Figure A is the top view structure diagram and Figure B is the three-dimensional structure diagram

[0052] Figure 14 a is the schematic diagram of the structure of the blocking structure

[0053] Figure 15 Schematic diagram of the excitation fuse structure in Embodiment 3 (at the initial position)

[0054] Figure 16 Schematic diagram of the structure when the second moving part of the piston contacts the limit post after the conductive busbar in Embodiment 3 is disconnected

[0055] Figure 17 Schematic diagram of the structure when the air flow channel of the second moving part is exposed after the first moving part of the piston moves to the end position and the conductive busbar in Embodiment 3 is disconnected

[0056] Figure 18 Schematic diagram of the structure when the long melt cutter disconnects the melt after the first moving part of the piston moves to the end position and the conductive busbar in Embodiment 3 is disconnected

[0057] Figure 19 Schematic diagram of the structure when the short melt cutter disconnects the melt after the conductive busbar in Embodiment 3 is disconnected

[0058] Figure 20 Schematic diagram of the structure of the second moving part of the piston in Embodiment 3

[0059] Figure 21 Schematic diagram of the three-dimensional partial sectional view in Embodiment 3

[0060] Figure 22 Schematic diagram of the structure of the guide cover plate in Embodiment 3, where Figure A is the top view structure diagram and Figure B is the three-dimensional structure diagram

[0061] Figure 23 is Figure 15 Schematic diagram of adding a guide boss on the second housing on the basis of

[0062] Reference numerals:

[0063] Electronic ignition device 201, first housing 202, sealing ring 203, first moving part 204 of the piston, second moving part 205 of the piston, air flow channel 205a, conductive busbar 206, second housing 207, limiting post 207a, fuse element 208, buffer bushing 209, fuse element cutter 210, arc extinguishing medium 211, bottom protective cover 212;

[0064] Electronic ignition device 601, upper cover 602, first housing 603, sealing ring 604, first moving part 605 of the piston, second moving part 606 of the piston, limiting part 606a, column body part 606b, air flow guiding rib 606c, conductive busbar 607, second housing 608, fuse element upper cover 609, limiting post 609a, fuse element lower cover 610, insulating buffer pad 611, bottom protective cover 612, blocking structure 613, supporting end face 613a, blocking structure main body 613b, limiting boss 613c, buffer bushing 614, gas buffer groove 614a, through hole 614b, fuse element 615, arc extinguishing medium 616, long fuse element cutter 617, short fuse element cutter 618, guiding boss 619.

[0065] Electronic ignition device 1101, upper cover 1102, first housing 1103, sealing ring 1104, first moving part 1105, second moving part 1106, limiting part 1106a, column body part 1106b, air flow guiding rib 1106c, conductive busbar 1107, second housing 1108, buffer bushing 1109, limiting post 1109a, limiting boss 1109b, connecting block 1109c, fuse element upper cover 1110, fuse element lower cover 1111, fuse element 1112, arc extinguishing medium 1113, long fuse element cutter 1114, short fuse element cutter 1115, insulating buffer pad 1116, bottom protective cover 1117, guiding boss 1118. Detailed implementation mode

[0066] The excitation fuse with a delay-disconnecting fuse element of the present invention includes an electronic ignition device, a piston, a conductive busbar, a limiting post structure, and a fuse structure; the fuse structure includes a fuse housing, an arc extinguishing medium filled in the fuse housing, and a fuse element passing through the arc extinguishing medium, and both ends of the fuse element extend out of the fuse housing;

[0067] The electronic ignition device and the piston are arranged on one side of the conductive busbar, the fuse structure is located on the other side of the conductive busbar, and the fuse element is connected in parallel with the conductive busbar; the electronic ignition device operates according to the received trigger signal and can drive the piston to displace and cut off the conductive busbar;

[0068] A displacement channel is provided along the piston displacement direction in the fuse structure. At least one end of the displacement channel penetrates one end of the fuse structure where it is located. A melt cutter is arranged in the displacement channel, and the melt passes through the displacement channel and is located on the displacement path of the melt cutter. The piston includes a first moving part and a second moving part that can move relative to each other. A receiving through hole that penetrates both ends along its displacement direction is formed in the first moving part, and the second moving part is located in the receiving through hole of the first moving part.

[0069] The second moving part includes a limiting part and a column body part with a columnar structure that are integrally connected. The outer diameter of the column body part is smaller than the outer diameter of the limiting part. On the outer side surface of the column body part of the second moving part, air flow guiding ribs protruding from the outer side surface of the column body part are arranged along the length direction of the column body part. At least two air flow guiding ribs are distributed at intervals along the circumferential direction of the column body part, and an air flow channel is formed between adjacent two air flow guiding ribs. Alternatively, on the outer side surface of the column body part, at least one long strip-shaped air duct guiding groove that penetrates one end of the column body part facing the fuse structure direction is arranged along the length direction of the column body part, and the air duct guiding groove forms an air flow channel.

[0070] In the initial position, the limiting part of the second moving part closes one end of the receiving through hole of the first moving part facing the electronic ignition device and the air flow channel.

[0071] The limiting column structure is fixedly arranged on the displacement path of the second moving part to prevent the second moving part from displacing, causing relative displacement between the first moving part and the second moving part, and making the air flow channel conduct. The conducted air flow channel connects the chamber where the melt cutter or one end of the fuse structure facing the conductive busbar is located and the chamber where one end of the driving force release of the electronic ignition device is located.

[0072] When an overload, short-circuit current or abnormal situation occurs in the electrical circuit where the excitation fuse is located, the electronic ignition device acts according to the received trigger signal and releases high-pressure gas, driving the first moving part and the second moving part to displace synchronously. After the first moving part cuts off the conductive busbar, the limiting column structure prevents the second moving part from displacing, and the first moving part displaces relative to the second moving part, and the air flow channel conducts. The high-pressure gas released by the electronic ignition device flows through the air flow channel, driving the melt cutter to displace and cut off the melt, or driving the fuse structure to displace, so that the melt cutter cuts off the melt.

[0073] Specific descriptions will be given for the above technical solutions by taking preferred embodiments in combination with the drawings.

[0074] Embodiment 1

[0075] Refer to Figures 2 to 6, the time-delay disconnection melt excitation fuse of the present invention includes an electronic ignition device 201, a first housing 202, a sealing ring 203, a piston, a conductive busbar 206, a second housing 207, a melt 208, a buffer bushing 209, a melt cutter 210, an arc extinguishing medium 211, and a bottom protective cover 212. The first housing, the piston, the second housing, the buffer bushing, and the melt cutter are all made of insulating materials. Among them:

[0076] The first housing 202, the second housing 207, and the bottom protective cover 212 are sequentially spliced to form a housing structure. The conductive busbar 206 is arranged between the first housing 202 and the second housing 207, and both ends of the conductive busbar 206 are located outside the housing and serve as the connection ends of the excitation fuse. The electronic ignition device 201 and the piston are sequentially arranged in the first housing 202, and the piston is located between the conductive busbar 206 and the electronic ignition device 201.

[0077] The electronic ignition device 201 closes the first housing 202. In this embodiment, the electronic ignition device is a gas generating device, which is triggered to act by receiving a trigger signal, releases high-pressure gas as a driving force, and drives the piston to displace.

[0078] The conductive busbar 206 is provided with a disconnection weak point for reducing mechanical strength at the impact end corresponding to the piston, which facilitates the conductive busbar 206 to be disconnected from a preset position (disconnection weak point) when being disconnected by the piston, forming an air break.

[0079] The piston includes a first moving part 204 and a second moving part 205 that can displace relative to each other. The longitudinal section of the first moving part 204 is T-shaped, and a through accommodating through hole is opened along the piston displacement direction in the first moving part 204, and a limiting step is opened at a position of the accommodating through hole close to the electronic ignition device 201. A sealing ring 203 is arranged on the contact surface where the first moving part 204 contacts the first housing 202, so that the piston forms a sealed contact with the first housing. At the initial position, a sealed cavity is formed between the piston and the electronic ignition device. The initial position of the piston is limited through the sealing ring 203. The second moving part 205 has a columnar structure. It includes a limiting part and a column body part formed integrally, and the outer diameter of the limiting part is larger than the outer diameter of the column body part. The second moving part 205 is arranged in the accommodating through hole of the first moving part 204, and its limiting part is located at the limiting step in the accommodating through hole, realizing the initial position limitation of the second moving part 205. The contact surface between the second moving part and the accommodating through hole of the first moving part is in a small clearance fit. The distance between one end of the second moving part 205 close to the conductive busbar 206 and the conductive busbar is greater than the distance between the impact end of the first moving part 204 and the conductive busbar 206. That is, when the piston displaces to cut off the conductive busbar, the impact end of the first moving part 204 first contacts the conductive busbar to cut off the conductive busbar, and the second moving part 205 does not contact the conductive busbar and does not participate in the cutting of the conductive busbar.

[0080] An air flow channel 205a is provided on the second moving part 205. One end opening of the air flow channel 205a is located on the end face of the column body part, that is, on the end face of the end close to the conductive busbar, and the other end opening is located on the side face of the limiting part. A plurality of openings communicating with the air flow channel can be evenly arranged along the outer peripheral circumference direction on the side face of the limiting part. When the second moving part 205 is in the initial position, the first moving part 204 closes the opening end of the air flow channel 205a located at the limiting part of the second moving part, so that the air flow channel is not communicated with the cavity where one end of the driving force of the electronic ignition device is released. When the first moving part 204 and the second moving part 205 have a relative displacement, the second moving part 205 displaces relative to the first moving part 204 towards the direction of the electronic ignition device. When the opening end of the air flow channel of the second moving part 205 is located outside the first moving part 204, the air flow channel of the second moving part 205 is communicated with the cavity where one end of the driving force of the electronic ignition device is located, and the high-pressure gas can flow through the air flow channel of the second moving part.

[0081] The second housing 207 is provided with accommodation grooves at both ends thereof, so that cavity structures are respectively formed between the second housing and the conductive busbar and between the second housing and the bottom protection cover. A limiting post 207a is provided at a position corresponding to the second moving part 205 of the piston on the bottom surface of the second housing 207 facing the conductive busbar, and the limiting post is located on the displacement path of the second moving part. A through hole penetrating the bottom of the second housing 207 is opened on the limiting post 207a corresponding to the gas flow channel of the second moving part 205, so as to communicate the cavity between the second housing and the conductive busbar and the cavity between the second housing and the bottom protection cover. A buffer bushing 209 is nested on the bottom surface of the second housing 207 facing the bottom protection cover 212, and the buffer bushing 209 covers one end of the through hole penetrating the second housing 207. When the high-pressure gas passes through the through hole, it can act on the buffer bushing 209 for the first time to drive the buffer bushing 209 to displace. The buffer bushing 209 is in a cover-like structure, and the protruding edge is nested on the second housing 207.

[0082] An arc extinguishing chamber and a displacement channel are provided between the bottom protection cover 212 and the second housing 207. An arc extinguishing medium 211 is filled in the arc extinguishing chamber, and the displacement channel is provided corresponding to the buffer bushing 209. The fuse 208 passes through the arc extinguishing medium 211 and the displacement channel. A through hole for the fuse 208 to pass through is opened on the shell wall of the second housing 207. Both ends of the fuse 208 pass through the through holes on the shell wall of the second housing 207 and are electrically connected to the conductive busbar 206, so that the fuse 208 is connected in parallel on the conductive busbar. When the fuse 208 is connected in parallel on the conductive busbar, the disconnected part of the conductive busbar needs to be located on the conductive busbar between both ends of the fuse 208. The arc extinguishing chamber, the arc extinguishing medium and the fuse form a parallel fuse structure connected in parallel on the conductive busbar.

[0083] The melt cutter 210 is arranged in the displacement channel in an interference fit manner, and one end of the melt cutter 210 facing the buffer bushing 209 protrudes out of the displacement channel and is located outside the displacement channel.

[0084] Working principle:

[0085] When there is an overload, short-circuit current or abnormal situation (abnormal situations, such as a new energy vehicle colliding, catching fire, etc.), the electronic ignition device acts according to the received trigger signal, releases high-pressure gas as the driving force, drives the piston to displace, and the first moving part 204 of the piston first contacts the conductive busbar 206 and disconnects the conductive busbar 206. At this time, the first moving part 204 also reaches the bottom of the groove of the second housing 207, and the second moving part 205 contacts the limit post 207a of the second housing 207. The limit post 207a forms a movement obstacle to the second moving part 205, and the second moving part stops displacing. The first moving part 204 then continues to displace relative to the second moving part to the end position, and only then does the air flow channel on the second moving part 205 change from the state of being blocked by the first moving part to the open state. The air flow channel communicates with the cavity where the driving force release end of the electronic ignition device is located. The high-pressure gas flows through the air flow channel and the through hole on the limit post of the second housing, and drives the buffer bushing 209 to displace. The buffer bushing 209 then drives the melt cutter 210 to displace along the displacement channel and cut off the melt 208.

[0086] Arc extinguishing principle:

[0087] When the conductive busbar conducts current normally, since the resistance of the melt is much greater than that of the conductive busbar, almost no current or very little current flows through the melt and can be ignored. When the conductive busbar is cut off, the current flows through the melt 208. After the conductive busbar is cut off, an air break is formed. Since almost all the current flows through the melt 208 during the process from the formation of a high impedance to the complete disconnection of the conductive busbar, the arc at the break of the conductive busbar is very small and is easily extinguished through the air; since the resistance of the melt is very large, after sufficient current limiting is achieved through the melt, the current on the melt will be reduced. When the melt is disconnected, the arc generated at the break of the melt is first reduced several times for the large current, and the break of the melt is located in the arc extinguishing medium, and the arc is directly extinguished through the arc extinguishing medium.

[0088] When the melt is disconnected without delay, after the conductive busbar is disconnected, the melt is immediately disconnected. At this time, the melt has not fully achieved the current limiting effect, and the current on the melt is still relatively large. Then, the arc generated when the melt is disconnected is relatively large, and the arc extinguishing difficulty increases. Therefore, it is necessary for the melt to be disconnected with a delay to enable the melt to achieve sufficient current limiting, which is also the invention purpose of the present invention.

[0089] Advantages of this technical solution:

[0090] 1. The high-pressure gas triggered by the ignition device, through the pressure reduction of the gas flow path of the second moving part in the piston and the through hole of the second housing, reduces the pressure of the high-pressure gas to medium-pressure gas, thereby reducing the driving force. The displacement speed when driving the buffer bushing to displace decreases. As the buffer bushing displaces, the cavity between the buffer bushing and the second housing gradually increases, so the gas pressure gradually decreases, and the displacement speed of the buffer bushing gradually decreases. The decrease in displacement speed prolongs the displacement time of the buffer bushing, that is, prolongs the melt flow-through time; after two slowdowns, the time for the melt to flow through and fuse is prolonged, enabling the melt to fully limit the current and improving the breaking capacity of this incentive fuse.

[0091] 2. Since the buffer bushing has a certain mass, it will also slow down the acceleration of the low-pressure gas impacting downward. After two processes of speed reduction, the time for the melt to flow through and fuse is prolonged, enabling the melt to fully fuse and limit the current, and improving the breaking capacity of this incentive fuse.

[0092] 3. The time for the melt to flow through and fuse is effectively prolonged, making the loop current that needs to be cut off by the melt lower, effectively reducing the strength requirement of the melt cutter, and simultaneously reducing the arc voltage at the melt fracture. This improves the breaking capacity of this incentive fuse.

[0093] 4. After the high-pressure gas is decompressed by the piston, it pushes the buffer bushing to push the melt cutter, completing the function of protecting the melt from being cut. Compared with the scheme of directly using the piston cutter to cut the melt by the gas, the melt flow-through time is effectively prolonged.

[0094] 5. The weight of the piston is about a few grams (generally 2 - 5 grams), and the weight of the buffer bushing is more than 10 grams. In the same spatial size, more delay time is generated, thus giving the melt more working time to fully limit the current and extinguish the arc.

[0095] Embodiment 2

[0096] Based on the structure of Embodiment 1, a structural change design is carried out.

[0097] Refer to Figures 7 to 14 a. The incentive fuse of this embodiment includes an electronic ignition device 601, an upper cover 602, a first housing 603, a sealing ring 604, a piston, a first moving part 605 of the piston, a second moving part 606 of the piston, a conductive bus bar 607, a second housing 608, a melt upper cover 609, a melt lower cover 610, an insulating buffer pad 611, a bottom protection cover 612, a blocking structure 613, a buffer bushing 614, a melt 615, an arc extinguishing medium 616, a long melt cutter 617, and a short melt cutter 618, where:

[0098] The upper cover 602, the first housing 603, the second housing 608, and the bottom protection cover 612 are spliced in sequence to form a complete housing structure. The electronic ignition device 601 is arranged in the upper cover 602, the piston is arranged in the first housing 603, and the conductive busbar 607 is arranged between the first housing and the second housing.

[0099] The piston includes a first moving part 605 and a second moving part 606. The main difference from the piston structure of Embodiment 1 is that: a circumferential outwardly protruding limiting rib is arranged on the outer periphery of one end of the first moving part 605 facing the electronic ignition device, and the limiting rib is placed on the end face of the first housing on the side of the upper cover to realize the initial position limitation of the piston. The contact seal between the piston and the first housing is realized by the sealing ring 604 arranged on the outer periphery of the first moving part.

[0100] An air flow channel is not directly opened in the second moving part 606. The second moving part 606 includes a limiting part 606a and a column body part 606b. Several air flow guiding ribs 606c are evenly spaced in the circumferential direction on the outer periphery of the column body part 606b of the second moving part 606. The length of the air flow guiding ribs is arranged along the length direction of the column body part, and the length of the air flow guiding ribs penetrates the length of the column body part. A strip-shaped groove penetrating the length of the column body part is formed between adjacent air flow guiding ribs as the air flow channel. When the second moving part 606 is arranged in the first moving part 605, the limiting part 606a of the second moving part is in sealed contact with the accommodating through hole of the first moving part, so that the strip-shaped groove of the column body part serving as the air flow channel is not communicated with the cavity where the high-pressure gas release end of the electronic ignition device is located. When the first moving part and the second moving part have relative displacement, when the limiting part of the second moving part is displaced to the outside of the accommodating through hole of the first moving part, the strip-shaped groove serving as the air flow channel is communicated with the cavity where the high-pressure gas release end of the electronic ignition device is located.

[0101] With such a structure, the volume of the air flow channel can be increased, and the weight of the second moving part can be reduced. In order to further reduce the weight of the second moving part, a through hole is opened along the length direction of the center of the column body part to reduce the weight of the second moving part.

[0102] Disconnection weak points are respectively arranged on the two surfaces of the conductive busbar 607 at the impact end position corresponding to the first moving part 605 of the piston. The first moving part disconnects the conductive busbar from the disconnection weak points, and the disconnected part of the conductive busbar is attached to the impact end part located in the first moving part.

[0103] The second housing 608 is connected to the first housing at one end and to the bottom protective cover at the other end. At one end of the second housing 608 in contact with the conductive busbar, it is connected to the conductive busbar by screws. A guiding boss 619 protruding towards the bottom protective cover is provided at the position of the second housing 608 corresponding to the piston. A through hole penetrating one end of the second housing 608 towards the conductive busbar and the guiding boss 619 is provided on the guiding boss 619, and the piston can displace along the through hole of the guiding boss 619 after disconnecting the conductive busbar.

[0104] An insulating buffer pad 611 is provided between the second housing 608 and the bottom protective cover 612, and the insulating buffer pad 611 is arranged in a fitting manner with the bottom protective cover 617. A melt upper cover 609 and a melt lower cover 610 are provided in the second housing 608. The melt upper cover 609 covers the melt lower cover 610 to seal it. The melt upper cover and the melt lower cover are fixed in position relative to the second housing 608 and will not undergo relative displacement. The combined shape of the melt upper cover and the melt lower cover is a housing of a fuse structure with a concave structure, and one end of the guiding boss 619 of the second housing 608 is located in the groove of the concave structure.

[0105] A plurality of displacement channels are spaced apart at the groove of the concave structure of the melt upper cover and the melt lower cover. The displacement channels penetrate both ends of the melt upper cover and the melt lower cover in the displacement direction of the piston. An arc extinguishing chamber is formed between the melt upper cover and the melt lower cover on both sides of the displacement channel, and an arc extinguishing medium 616 is filled in the arc extinguishing chamber. The melt 615 is arranged in the arc extinguishing medium between the melt upper cover and the melt lower cover and passes through the displacement channel. Both ends of the melt 615 pass through the second housing and are conductively connected to the conductive busbar. The melt upper cover, the melt lower cover, the arc extinguishing medium, and the melt form a parallel fuse structure connected in parallel to the conductive busbar.

[0106] A long melt cutter 617 and a short melt cutter 618 are respectively arranged in the displacement channels. The long melt cutter 617 and the short melt cutter 618 respectively protrude from the end face of the melt upper cover towards the conductive busbar in the direction of the conductive busbar. The distance between the long melt cutter 617 and the conductive busbar is less than the distance between the short melt cutter 618 and the conductive busbar. Limiting protrusions (not shown) are arranged on opposite sides of the long melt cutter 617 and the short melt cutter 618, and the limiting protrusions are located in the grooves at the openings of the displacement channels to realize the initial position positioning of the long melt cutter 617 and the short melt cutter 618.

[0107] A limit column 609a is provided on the melt cover 609, facing the conductive busbar and protruding from the bottom of the melt cover 609. The limit column 609a extends into the through hole of the guide boss 619. The limit column 609a is provided corresponding to the second moving part and is located on the displacement path of the second moving part. The blocking structure 613 is provided in the through hole of the guide boss 619 in an interference fit or a close fit manner. The blocking structure 613 and the inner wall of the through hole of the guide boss 619 retain a gap for gas to pass through. Blocking structure 613, see Figure 14 a, is a flat plate structure, including a support end face 613a and a blocking structure body 613b. A through hole that penetrates the thickness of the blocking structure 613 for the limiting column 609a to pass through is provided on the blocking structure body 613b. The through hole is provided with a support end face 613a integrally connected to the inner wall of the through hole. The support end face is a hollow structure of a cross-shaped structure, and the connection between the support end face and the inner wall of the through hole is set as a disconnection weak point. The support end face 613 of the blocking structure 613 is located on the end face of the limiting column 609a.

[0108] On the opposite sides of the through hole, the end faces of the blocking structure body 613b corresponding to the disconnected part of the conductive busbar facing the conductive busbar are respectively provided with limiting bosses 613c protruding from the end faces, and the limiting bosses are used to support the disconnected part of the conductive busbar. When the blocking structure 613 is impacted by the first moving part, under the clamping and fixing action of the limiting column 609a and the second moving part, the supporting end face 613a is disconnected from the blocking structure body 613b, detached from the blocking structure body 613b, and fixed between the limiting column 609a and the second moving part, and the blocking structure body 613b, driven by the first moving part, passes through the limiting column 609a, and moves along the through hole of the guide boss 619 toward the buffer bushing 614 until the first moving part stops moving when it moves to the end position. During this process, the disconnected portion of the conductive busbar is driven by the first moving part to move to the limiting boss at the blocking structure body 613b, and continues to be driven by the first moving part, and the disconnected portion of the conductive busbar moves to the end position along with the blocking structure body 613b through the limiting column.

[0109] And the high-pressure gas flow in this process: the second moving part is relatively displaced with the first moving part due to the action of the limiting column, and the airflow channel on the second moving part is connected to the chamber where the high-pressure gas release end of the electronic ignition device is located, and the high-pressure gas enters the chamber where the end of the buffer liner 614 facing the conductive busbar is located through the airflow channel and the gap between the blocking structure and the through hole of the guide boss 619. The setting of the blocking structure 613 can slow down the displacement speed of the first moving part. At the same time, when the airflow channel is connected, the high-pressure gas enters the airflow channel and is decompressed once. When it reaches the blocking structure, the pressure of the high-pressure gas is released to a certain extent due to the increase in the cavity volume, and a secondary decompression is achieved at the blocking structure.

[0110] A buffer bushing 614 is provided between the melt long cutter 617 on the melt upper cover 609 and the guiding boss 619 of the second housing. The buffer bushing 614 is sleeved on the outer periphery of one end of the guiding boss 619 facing the bottom protective cover and is supported by the melt long cutter 617. The melt short cutter 618 does not contact the buffer bushing 614. The buffer bushing 614 is in a boxed structure and has a gas buffer groove 614a. Since the buffer bushing is sleeved on the outer periphery of the guiding boss 619, the gas buffer cavity formed by the gas buffer groove 614a of the buffer bushing is communicated with the through hole of the guiding boss 619. When the gas with a certain pressure flows through the blocking structure to the gas buffer groove, the gas pressure will be further reduced to achieve buffering. A through hole 614b penetrating the thickness of the buffer bushing for the limit post to pass through is provided on the buffer bushing 614, and the limit post is inserted into the through hole.

[0111] Working principle:

[0112] When there is an overload, short - circuit current or abnormal situation (abnormal situations, such as when a new - energy vehicle collides, catches fire, etc.), the electronic ignition device acts according to the received trigger signal, releases high - pressure gas, and drives the first moving part and the second moving part of the piston to displace synchronously. The first moving part of the piston first contacts the conductive busbar and cuts the conductive busbar from the weak break point. Then, the first moving part of the piston drives the disconnected part of the conductive busbar and continues to displace synchronously with the second moving part along the guiding boss to the blocking structure, so that the disconnected part of the conductive busbar contacts the limit boss on the main body of the blocking structure. The displacement speed of the first moving part is reduced through the blocking structure. At the same time, under the combined action of the drive of the first moving part and the limit post, the supporting end face of the blocking structure and the main body of the blocking structure are disconnected. The supporting end face is clamped between the limit post and the second moving part, and the second moving part stops displacing. The first moving part continues to drive the disconnected part of the conductive busbar and the main body of the blocking structure to displace through the limit post until the termination position. At the termination position: one end of the first moving part facing the electronic ignition device displaces to the conductive busbar, and the conductive busbar forms a position limit for the first moving part, and the first moving part stops. During the relative displacement of the first moving part and the second moving part, the limiting part of the second moving part is located outside the first moving part, and the air flow channel of the second moving part is communicated with the cavity where the high - pressure gas release end of the electronic ignition device is located. The high - pressure gas enters the gas buffer cavity of the buffer bushing through the air flow channel of the second moving part, the gap between the supporting end face and the limit post, and the gap between the main body of the blocking structure and the through hole of the guiding boss 619, drives the buffer bushing to displace, and the buffer bushing drives the melt long cutter to displace to first disconnect the melt, and then drives the melt short cutter to displace to disconnect the melt, so that the melt is disconnected successively.

[0113] The arc - extinguishing principle is the same as that of Embodiment 1.

[0114] During the synchronous displacement of the first moving part and the second moving part of the piston until the first moving part is displaced relative to the second moving part, the high-pressure gas is decompressed through the air flow channel of the second moving part to become medium-pressure gas, and then enters the buffer bushing through the gap between the blocking structure and the limit post structure. The gas buffer groove of the buffer bushing further reduces the pressure to form low-pressure gas, and the low-pressure gas drives the buffer bushing to displace, sequentially pushing the melt long cutter and the melt short cutter to displace and disconnect the melt successively.

[0115] By the synchronous displacement of the first moving part and the second moving part of the piston until the first moving part is displaced relative to the second moving part, the high-pressure gas is depressurized twice, the driving force is reduced, the displacement speed of the buffer bushing is reduced, and the displacement time of the buffer bushing is extended to achieve the delayed cutting of the melt.

[0116] Due to the setting of the blocking structure, the impact force of the first moving part can be effectively relieved, the displacement speed of the first moving part is reduced, and the relative displacement time of the first moving part and the second moving part is lengthened; combined with the setting of the gas buffer groove through the buffer bushing to buffer the impact force of the gas on the buffer bushing, reduce the gas pressure, compared with Embodiment 1, further reduce the gas pressure, thereby reducing the displacement speed of the buffer bushing and extending the displacement time of the buffer bushing from the initial position to the termination position, so as to effectively extend the melt disconnection time.

[0117] Advantages of this embodiment:

[0118] 1. The high-pressure gas triggered and released by the electronic ignition device is decompressed through the air flow channel of the second moving part in the piston, slowed down to medium-pressure gas, and then buffered to low-pressure gas through the air flow buffer chamber of the buffer bushing. After two slowdowns, the gas pressure can be effectively reduced, the driving force can be reduced, the melt disconnection time can be extended, ensuring that the melt has enough time for current-carrying fusing, making the melt fully current-limiting, and improving the breaking capacity of the excitation fuse.

[0119] 2. In the structural design of the second moving part of the piston, there are multiple air flow guiding ribs, which not only enhance the structural strength of the second moving part, but also play a role in guiding and dispersing the gas flow direction, making the high-pressure gas flow evenly, and having a certain guiding and decompressing effect.

[0120] 3. In this buffer bushing, there is an air flow buffer chamber, so that the medium-pressure gas flowing out of the second moving part is evenly distributed and acts on the air flow chamber in the buffer bushing, thereby slowing down the impact force of the medium-pressure gas and forming low-pressure gas. And the structure is symmetrical, making the low-pressure gas evenly distributed, and the buffer bushing is relatively stable during the downward movement.

[0121] 4. Since the buffer bushing has a certain mass, it also slows down the acceleration of the low-pressure gas hitting downward. After two processes of speed reduction, the time for the melt to flow through and fuse is extended, enabling the melt to fully fuse and limit the current, thereby improving the breaking capacity of this incentive fuse.

[0122] 5. The time for the melt to flow through and fuse is effectively extended, making the loop current that the melt needs to cut off lower, effectively reducing the strength requirement for the melt cutter, and simultaneously reducing the arc voltage at the melt fracture. This improves the breaking capacity of this incentive fuse.

[0123] 6. At the bottom of the buffer bushing, melt cutters with different lengths are set at different positions, causing the melting of the melt to occur at different positions and different times. Compared with cutting the melt simultaneously, it can effectively reduce the arc voltage.

[0124] 7. After the high-pressure gas is decompressed by the piston, it pushes the buffer bushing to push the long / short melt cutters, completing the function of melt cutting protection. Compared with the scheme of directly using the piston cutter to cut the melt by the gas, the melt cutting time is effectively slowed down. The weight of the piston cutter is about a few grams (2 - 5 grams), and the weight of the buffer bushing is more than 10 grams. In the same spatial size, more delay time is generated, thus giving the melt more working time to fully limit the current and extinguish the arc.

[0125] Embodiment 3

[0126] The incentive fuse of this embodiment includes an electronic ignition device 1101, an upper cover 1102, a first housing 1103, a sealing ring 1104, a piston, a first moving part 1105, a second moving part 1106, a conductive busbar 1107, a second housing 1108, a buffer bushing 1109, a melt upper cover 1110, a melt lower cover 1111, a melt 1112, an arc extinguishing medium 1113, a long melt cutter 1114, a short melt cutter 1115, an insulating buffer pad 1116, and a bottom protection cover 1117. See Figures 15 to 22 , where:

[0127] The upper cover 1102, the first housing 1103, the second housing 1108, and the bottom protection cover 1117 are sequentially spliced to form a complete housing structure. The electronic ignition device 1101 is arranged in the upper cover 1102 and closes the upper cover 1102. The piston is arranged in the first housing 1103, and the conductive busbar 1107 is arranged between the first housing and the second housing.

[0128] The piston includes a first moving part 1105 and a second moving part 1106. The main difference from the piston structure of Embodiment 2 is that a groove is provided at the end face of the first moving part 1105 facing the electronic ignition device. The contact seal between the piston and the first housing is realized through the sealing ring 1104 arranged on the outer periphery of the first moving part.

[0129] The second moving part 1106 includes a limiting part 1106a and a column body part 1106b. Airflow guiding ribs 1106c are arranged at intervals on the column body part, and an airflow channel is formed between two adjacent airflow guiding ribs. The structural difference from the second moving part 606 in Embodiment 2 is that the length of the column body part 1106b in this embodiment is relatively short. When the second moving part is arranged in the first moving part, the distance between the second moving part and the conductive busbar is much greater than the distance between the first moving part and the conductive busbar, leaving enough displacement distance in the first moving part and extending the displacement distance of the second moving part to the limiting column. Compared with Embodiment 2, the mass of the second moving part is smaller and the weight of the piston is lighter.

[0130] The structure of the conductive busbar 1107 is the same as that in Embodiment 2.

[0131] The second housing 1108 is a cylindrical structure with both ends penetrating. One end of it is connected to the first housing, and the other end is connected to the bottom protection cover. The end connected to the bottom protection cover is an open end. An insulating buffer pad 1116 is located between the second housing 1108 and the bottom protection cover 1117, and the insulating buffer pad 1116 is arranged in a fitting manner with the bottom protection cover 1117.

[0132] An insulating guiding cover plate 1109 is arranged at one end of the second housing 1108 adjacent to the conductive busbar 1107. The guiding cover plate 1109 is connected to the conductive busbar 1107 by screws. The guiding cover plate 1109 has a boxed structure with one end open and one end closed, and a sufficient cavity is formed in the guiding cover plate 1109 to form a gas buffer chamber. The open end of the guiding cover plate is located on the side of the conductive busbar. Notches for arranging the conductive busbar are arranged on the opposite sides of the open end of the guiding cover plate 1109. Connecting blocks 1109c are arranged on the outer side of the guiding cover plate where the notches are located, and the connecting blocks are connected to the conductive busbar by screws. A limiting column 1109a protruding towards the second moving part is arranged at the bottom in the guiding cover plate 1109 corresponding to the position of the piston second moving part 1106. Both ends of the limiting column 1109a are through hollow structures. A diverging structure in an inverted Y shape is protrudingly arranged at the end of the limiting column towards the second moving part. The diverging structure in an inverted Y shape is formed by three side walls connected at an angle, and sufficient space is formed between adjacent side walls to allow gas to enter the through hollow part of the limiting column through the space of the diverging structure in an inverted Y shape. The hollow structure of the limiting column 1109a can communicate with the cavities at both ends of the guiding cover plate, and gas can enter the hollow part of the limiting column 1109a through the diverging structure with a triangular fork, and then enter the cavity between the guiding cover plate 1109 and the bottom protection cover. The free end of the limiting column 1109 passes through the displacement path of the second moving part of the conductive busbar 1107 in the first housing 1103.

[0133] On opposite sides of the limit post 1109a, limit bosses 1109b for support and limitation are respectively provided at positions corresponding to the disconnected parts of the conductive busbar to replace the blocking structure in Embodiment 2.

[0134] A melt upper cover 1110 and a melt lower cover 1111 are successively arranged between the guiding cover plate 1109 and the insulating buffer pad 1116. The melt upper cover 1110 is sleeved on the outer periphery of the guiding cover plate 1109, and a gap is reserved between the bottom end face of the guiding cover plate 1109 and the melt upper cover 1109. Several grooves are provided at the position of the melt upper cover where the bottom end face of the guiding cover plate 1109 is located. When gas with a certain pressure enters between the guiding cover plate 1109 and the melt upper cover through the limit post, the grooves at the melt upper cover can buffer the gas impact force and reduce the gas pressure.

[0135] A displacement distance is reserved between the melt lower cover 1111 and the insulating buffer pad 1116. Several displacement channels are respectively opened on the melt upper cover and the melt lower cover where the bottom end face of the guiding cover plate 1109 is located. An arc extinguishing chamber is formed between the melt upper cover and the melt lower cover on both sides of the displacement channel, and an arc extinguishing medium 1113 is filled in the arc extinguishing chamber. The melt 1112 is arranged in the arc extinguishing medium between the melt upper cover and the melt lower cover and passes through the displacement channel. Both ends of the melt 1112 pass through the contact surfaces of the melt upper cover and the melt lower cover and then pass through the guiding cover plate and are electrically connected to the conductive busbar to form a melt connected in parallel with the conductive busbar. The melt part between the melt upper cover and the guiding cover plate is a bent compression structure. A long melt cutter 1114 and a short melt cutter 1115 are respectively arranged in the displacement channel. One end of the long melt cutter 1114 and the short melt cutter 1115 facing the guiding cover plate retains a displacement distance from the bottom of the guiding cover plate. The other end of the short melt cutter 1115 facing the insulating buffer pad 1116 retains a displacement distance from the insulating buffer pad 1116. The other end of the long melt cutter 1114 facing the insulating buffer pad 1116 abuts against the insulating buffer pad 1116. In this embodiment, the long melt cutter 1114 and the short melt cutter 1115 are respectively composed of a push block and a guiding block, and the melt is clamped between the push block and the guiding block. The long melt cutter 1114 and the short melt cutter 1115 are limited in their initial positions by limit bumps (not shown). The melt upper cover, the melt lower cover, the arc extinguishing medium and the melt form a fuse structure, and this fuse structure is connected in parallel to the conductive busbar.

[0136] Working principle:

[0137] When there is an overload, short - circuit current or abnormal situation, the electronic ignition device acts according to the received trigger signal, releases high - pressure gas, and drives the first moving part and the second moving part of the piston to displace synchronously. The first moving part of the piston first contacts the conductive busbar, cuts off the conductive busbar from the weak disconnection point, and then the first moving part of the piston drives the disconnected part of the conductive busbar and continues to displace synchronously with the second moving part until the second moving part contacts the limit post, at which time the second moving part stops displacing, and the first moving part continues to drive the disconnected part of the conductive busbar to continue displacing until it reaches the limit boss of the guide cover plate, and the first moving part stops displacing. During the relative displacement of the first moving part relative to the second moving part, the limiting part of the second moving part gradually displaces outward relative to the first moving part and finally moves to the outside of the first moving part. The air flow channel formed by the long - shaped groove of the column body part of the second moving part is communicated with the cavity where one end of the high - pressure gas released by the electronic ignition device is located. The high - pressure gas enters the gas buffer groove in the guide cover plate through the air flow channel part of the second moving part for buffering to form medium - pressure gas, and then enters the cavity between the guide cover plate and the melt upper cover through the hollow part of the limit post to further reduce the gas pressure to form low - pressure gas, driving the melt upper cover, melt lower cover, melt and melt short - cutting knife to displace together towards the insulating buffer pad direction, making the melt displace relative to the melt long - cutting knife, so that the melt long - cutting knife first cuts off the melt. Then, before the melt lower cover contacts the insulating buffer pad, the melt short - cutting knife first contacts the insulating buffer pad, and as the melt lower cover and the melt continue to displace, the melt short - cutting knife cuts off the melt.

[0138] The arc - extinguishing principle is the same as that of Embodiment 1.

[0139] Advantages of this embodiment:

[0140] 1. After the first moving part of the piston breaks the conductive busbar, since the second moving part of the piston is limited by the limit post, the first moving part continues to move downward, exposing the air flow channel. The high - pressure gas enters the air flow channel of the second moving part to achieve the first decompression and become medium - pressure gas, and then further buffers and decompresses in the gas buffer groove of the guide cover plate, enters the cavity between the melt upper cover and the guide cover plate through the limit post, further reduces the gas pressure to form low - pressure gas, and finally the gas pressure driving the melt upper cover to displace is reduced by at least 1 / 2 - 1 / 4.

[0141] 2. Compared with Embodiment 2, the guide cover plate of this example not only has a gas buffer chamber to slow down the gas impact force, but also is provided with a hollow limit post. When the gas decompressed by the gas buffer chamber passes through the hollow limit post again, its movement acceleration is slowed down again. The formed low - pressure gas pushes the subsequent parallel fuses, which has greater advantages in delaying the melting failure of the melt.

[0142] 3. The low-pressure gas pushes the parallel fuse downward through the guiding cover plate, and then dislocates with the melt long / short cutter, achieving the purpose of cutting off the melt. Since the parallel fuse (melt upper cover, melt lower cover, arc extinguishing medium, melt forming a parallel fuse in parallel with the conductive busbar) is relatively heavy, the acceleration and speed generated under the same force condition are much smaller than those of other solutions using a piston to cut the melt. The weight of the piston is about a few grams (2 - 5 grams), the weight of the buffer bushing in Embodiment 2 is about 15 grams, while the weight of the integrated parallel fuse is more than dozens of grams (40 grams). In the same spatial dimension, compared with Embodiment 2, the delay is increased by 100 microseconds to several milliseconds or more, thus giving the parallel fuse more working time to fully limit the current and extinguish the arc.

[0143] 4. Through the action of multiple decompressions, the time for the melt to conduct current and fuse is effectively extended, making the loop current that needs to be cut off by the melt lower, effectively reducing the strength requirement for the melt cutter, and at the same time reducing the arc voltage at the melt fracture, improving the breaking capacity of this excitation fuse.

[0144] See Figure 23 , on the basis of Embodiment 3, a guiding boss 1118 with a protruding end face is integrally formed at one end of the second housing facing the conductive busbar in the direction of the bottom protection cover. A through hole is provided in the guiding boss. The guiding cover plate 1109 is arranged at one end of the guiding boss of the second housing facing the bottom protection cover. The limiting posts 1109a and the limiting bosses 1109b of the guiding cover plate are respectively located in the through holes on the guiding boss, and the guiding cover plate is fixed on the second housing.

Claims

1. An excitation fuse with delayed disconnection of a fuse, characterized in that: It includes an electronic ignition device, a piston, a conductive busbar, a limit column structure, and a fuse structure; the fuse structure includes a fuse housing, an arc extinguishing medium filled in the fuse housing, and a melt penetrating the arc extinguishing medium, and both ends of the melt extend out of the fuse housing; The electronic ignition device and the piston are arranged on one side of the conductive busbar, the fuse structure is located on the other side of the conductive busbar, and the fuse is connected in parallel with the conductive busbar; the electronic ignition device is actuated according to the received trigger signal, and can drive the piston to move and cut off the conductive busbar; A displacement channel is provided on the fuse structure along the displacement direction of the piston, at least one end of the displacement channel passes through one end of the fuse structure where it is located, a melt cutter is provided in the displacement channel, the melt passes through the displacement channel and is located on the displacement path of the melt cutter; the piston comprises a first moving part and a second moving part which can be relatively displaced, the first moving part is provided with an accommodating through hole which passes through both ends along the displacement direction thereof, and the second moving part is located in the accommodating through hole of the first moving part; The second moving part comprises a limiting part and a columnar body part of a columnar structure connected in an integral manner, the outer diameter of the columnar body part is smaller than the outer diameter of the limiting part, and an airflow guiding rib protruding from the outer side surface of the columnar body part is arranged on the outer side surface of the columnar body part along the length direction of the columnar body part, and at least two of the airflow guiding ribs are spaced apart along the circumference direction of the columnar body part, and an airflow channel is formed between two adjacent airflow guiding ribs; or, on the outer side surface of the columnar body part, at least one long strip airflow guiding groove is arranged along the length direction of the columnar body part, penetrating through one end of the columnar body part toward the fuse structure, and the airflow guiding groove forms the airflow channel; In the initial position, the limiting portion of the second moving portion closes one end of the accommodating through hole of the first moving portion that faces the electronic ignition device and the air flow channel; The limiting column structure is fixedly arranged on the displacement path of the second moving part, and is used to prevent the second moving part from being displaced, so that the first moving part and the second moving part are relatively displaced, so that the air flow channel is connected, and the connected air flow channel connects the chamber where one end of the melt cutter or the fuse structure facing the conductive busbar is located and the chamber where the driving force release end of the electronic ignition device is located; When an overload, short-circuit current or abnormal condition occurs in the electrical circuit where the excitation fuse is located, the electronic ignition device releases high-pressure gas according to the received trigger signal, driving the first moving part and the second moving part to move synchronously. After the first moving part cuts off the conductive busbar, the limit column structure prevents the second moving part from moving, and the first moving part moves relative to the second moving part, and the airflow channel is connected; the high-pressure gas released by the electronic ignition device flows through the airflow channel, driving the melt cutter to move and cut off the melt, or driving the fuse structure to move, so that the melt cutter cuts the melt.

2. The excitation fuse according to claim 1, characterized in that: At least a plurality of the airflow guiding ribs or a plurality of the airway guiding grooves are evenly distributed along the circumference direction of the column body, so that evenly distributed airflow channels are formed along the circumference direction of the column body.

3. The excitation fuse according to claim 1, characterized in that: The second moving part is also provided with an air flow channel for the high-pressure gas to pass through. One end of the air flow channel is opened on the outer side surface of the limiting part, and the other end is opened on the end surface of the column body facing the limiting column structure. When the limiting part closes the end of the accommodating through hole of the first moving part facing the electronic ignition device, the air flow channel is closed at the same time.

4. The excitation fuse according to claim 1, characterized in that: A limiting step is arranged in the accommodating through hole of the first moving part in a direction toward the electronic ignition device; and the limiting part of the second moving part is arranged on the limiting step.

5. The excitation fuse according to claim 4, characterized in that: The end surface of the column portion of the second moving part facing the conductive busbar is arranged close to the impact end of the first moving part, or is arranged close to the limiting step in the first moving part.

6. The excitation fuse according to claim 1, characterized in that: When the melt cutter is driven to displace and cut off the melt, the fuse structure is fixedly arranged, a buffer structure is arranged between the melt cutter and the conductive busbar, and the chamber where the end face of the buffer structure facing the conductive busbar is located can be connected with the chamber where one end of the electronic ignition device high-pressure gas release is located through the airflow channel; the melt cutter protrudes from the displacement channel toward the buffer structure, and the melt cutter supports the buffer structure; the melt cutters are a group or at least two groups, and a group of the melt cutters is arranged corresponding to a group of the displacement channels. When the melt cutters are two or more groups, the lengths of the melt cutters protruding from the displacement channels are the same or different; the high-pressure gas can drive the buffer structure to displace through the airflow channel, and the displacement of the buffer structure drives the melt cutter to displace and cut off the melt. When the melt cutters are two or more groups, the melt cutters cut off the melt simultaneously or successively.

7. The excitation fuse according to claim 6, characterized in that: The limiting column structure is fixedly arranged on one side of the end face of the buffer structure facing the conductive busbar, and the limiting column structure is provided with through holes passing through both ends thereof. When the second moving part contacts the limiting column structure, the airflow channel is connected with the through hole of the limiting column structure, so that the cavity where one end of the buffer structure facing the conductive busbar is located is connected with the chamber where the end of the electronic ignition device driving force is released, and the high-pressure gas can drive the buffer structure to move through the airflow channel and the through hole of the limiting column structure.

8. The excitation fuse according to claim 7, characterized in that: It also includes a first shell, a second shell, and a bottom protective cover which are spliced ​​in sequence, and a receiving groove is respectively provided at one end of the second shell facing the conductive busbar and the other end of the second shell facing the bottom protective cover; the electronic ignition device and the piston are arranged in the first shell in sequence, and the conductive busbar is arranged between the first shell and the second shell; the buffer structure and the fuse structure are located in a cavity formed between the receiving groove of the second shell and the bottom protective cover; the limiting column structure is protrudingly arranged at the bottom of the receiving groove of the second shell facing the conductive busbar, and a through hole penetrating the limiting column structure and the second shell is arranged on the limiting column structure, and the receiving grooves at both ends of the second shell are connected through the through hole; the buffer structure is nested on the bottom of the receiving groove of the second shell facing the bottom protective cover, and the nested part of the buffer structure surrounds the through hole opening end of the limiting column structure; the fuse structure is supported by the bottom protective cover; when the limiting column structure contacts the second moving part, the airflow channel on the second moving part is connected with the through hole of the limiting column structure.

9. The excitation fuse according to claim 8, characterized in that: The limiting column structure protrudes and is fixedly arranged on an end face of the fuse structure facing the conductive busbar, the limiting column structure is located on one side of the end face of the buffer structure facing the bottom protective cover, and the limiting column structure passes through the buffer structure.

10. The excitation fuse according to claim 6, characterized in that: A blocking structure is arranged between the buffer structure and the conductive busbar, and the blocking structure is located on the displacement path of the piston; through holes for the limiting column structure to pass through are respectively arranged on the part of the conductive busbar to be disconnected and the blocking structure, and the blocking structure blocks the displacement speed of the first moving part after disconnecting the conductive busbar. After the first moving part disconnects the conductive busbar, the blocking structure and the first moving part can be driven to displace synchronously; the limiting column structure passes through the blocking structure and the disconnected part of the conductive busbar, and the limiting column structure prevents the second moving part from displacing, and a gap for gas to flow through is reserved between the through hole on the blocking structure and the limiting column structure; the first moving part continues to drive the blocking structure and the disconnected part of the conductive busbar to displace to the terminal position, so that the first moving part and the second moving part are relatively displaced, the airflow channel is conductive, and the high-pressure gas drives the buffer structure to displace through the gap between the airflow channel, the limiting column structure and the blocking structure.

11. The excitation fuse according to claim 10, characterized in that: It also includes an upper cover, a first shell, a second shell, and a bottom protective cover which are spliced ​​in sequence; the electronic ignition device is arranged on the upper cover, the piston is arranged in the first shell, the conductive busbar is inserted between the first shell and the second shell, and the buffer structure and the fuse structure are located in the second shell; a guide boss is protrudingly arranged in the second shell toward the bottom protective cover, and a through hole is opened on the guide boss to penetrate the guide boss and the end of the second shell toward the conductive busbar; the blocking structure is arranged in the through hole of the guide boss in a tightly fitting manner; the buffer structure is nested on the outer periphery of the end of the guide boss toward the bottom protective cover; the limit column structure is protrudingly arranged on the end face of the fuse structure toward the buffer structure; the through hole of the blocking structure is respectively provided with limit bosses on the opposite sides of the disconnected part of the conductive busbar; when the first moving part disconnects the conductive busbar, the first moving part drives the disconnected part of the conductive busbar and the second moving part to move synchronously until the air flow channel is connected to the chamber where the end face of the buffer structure toward the conductive busbar is located.

12. The excitation fuse according to claim 11, characterized in that: The blocking structure includes a hollow supporting end face and a blocking structure main body, the through hole is opened on the blocking structure main body, the supporting end face is integrally connected to the through hole, and the connection between the supporting end face and the through hole is a disconnection weak point; in the initial position, the limiting column structure is supported at the supporting end face toward one end of the conductive busbar; when the blocking structure is driven by the first moving part, the limiting column structure disconnects the supporting end face from the disconnection weak point connected to the through hole, and the limiting column structure carries the supporting end face through the through hole on the blocking structure main body and contacts the second moving part.

13. The excitation fuse according to claim 6, characterized in that: The buffer structure is provided with an airflow buffer chamber. When the first moving part and the second moving part are relatively displaced and the airflow channel is connected, the airflow buffer chamber of the buffer structure is connected with the airflow channel.

14. The excitation fuse according to claim 1, characterized in that: When the fuse structure is driven to displace, the fuse part between the fuse structure and the conductive busbar is bent; one end of the limit column structure is fixedly arranged between the fuse structure and the conductive busbar; one end of the fuse cutter away from the conductive busbar protrudes from the displacement channel; the fuse cutters are arranged in a group or at least in two groups, one group of the fuse cutters corresponds to one group of the displacement channel, and when the fuse cutters are arranged in two or more groups, the lengths of the fuse cutters protruding from the displacement channel are the same or different; When the fuse structure is displaced, the melt cutter reaches the end position first and then the fuse structure, and relative displacement occurs between the fuse structure and the melt cutter, so that the melt cutter cuts off the melt simultaneously or successively.

15. The excitation fuse according to claim 14, characterized in that: It also includes an upper cover, a first shell, a second shell, and a bottom protective cover which are sequentially spliced; the electronic ignition device is arranged on the upper cover, the piston is arranged in the first shell, the conductive busbar is arranged between the first shell and the second shell, the two ends of the second shell are connected, the fuse structure is located in the second shell and a displacement distance for the fuse structure to move is reserved between the second shell and the bottom protective cover; a guide cover plate for closing the end of the second shell is arranged at one end of the second shell facing the conductive busbar; an accommodating groove facing the part of the conductive busbar to be disconnected is provided on the end surface of the guide cover plate facing the conductive busbar, and a The limiting column structure, one end of the limiting column structure facing the piston pair passes through the conductive busbar and is located in the first shell; the limiting column structure is provided with a through hole that passes through the limiting column structure and the guide cover plate, and the cavities where the two ends of the guide cover plate are located are connected through the through holes on the limiting column structure; limiting bosses for receiving the disconnected parts of the conductive busbar are respectively arranged at the bottom of the accommodating grooves on the opposite sides of the limiting column structure corresponding to the part of the conductive busbar to be disconnected; the fuse structure is located between the guide cover plate and the bottom protective cover, and blocks the connection between the cavity where the bottom protective cover is located and the conductive cavity where the guide cover plate is located; the melt cutter protrudes out of the displacement channel toward the bottom protective cover; When the piston is displaced, the first moving part and the second moving part are displaced synchronously until the first moving part cuts off the conductive busbar, and then the second moving part contacts the limiting column structure to stop displacement, and the first moving part is displaced relative to the second moving part until the first moving part drives the disconnected part of the conductive busbar to the limiting boss of the guide cover plate; when the first moving part and the second moving part are relatively displaced, the airflow channel is connected, and the high-pressure gas enters the cavity where one end of the fuse structure is located toward the guide cover plate through the airflow channel and the through hole of the limiting column structure, driving the fuse structure to displace, so that the melt cutter contacts the bottom protective cover first, and then the fuse structure contacts the bottom protective cover, so that the melt cutter disconnects the melt.

16. The excitation fuse according to claim 15, characterized in that: A guide boss is provided at one end of the second shell facing the conductive busbar, the guide boss protrudes toward the direction of the fuse structure, and a through hole is opened on the guide boss, which passes through the guide boss and is used for displacement of the piston and the disconnected part of the conductive busbar; the guide cover plate is nested at one end of the guide boss facing the direction of the fuse structure, and the limiting column structure and the limiting boss on the guide cover plate are located in the through hole of the guide boss.

17. The excitation fuse according to any one of claims 8, 11 and 15, characterized in that: An insulating buffer pad is arranged between the second shell and the bottom protective cover, and the insulating buffer pad is arranged in contact with the bottom protective cover.

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