CN220873514U - Fuse for accelerating medium-multiplying power overcurrent fusing speed - Google Patents

Abstract

The utility model discloses a fuse for accelerating the medium-rate overcurrent fusing speed, which is characterized in that: the device comprises a first terminal, a second terminal, a first current-carrying device and a second current-carrying device which are connected in parallel between the first terminal and the second terminal; the first current carrying device comprises at least one first melt connecting a first terminal and a second terminal; the second current-carrying device comprises at least one medium-rate fast melting branch circuit connected with the first terminal and the second terminal; the medium-rate quick melting branch comprises a second melt and a disconnecting device which are connected in series, and the disconnecting device disconnects the first melt and the second melt before the first melt when the medium-rate is over-current. The fuse adopts the combination of the first current-carrying breaking device and the second current-carrying breaking device, so that the maximum breaking capacity of the fuse is ensured, and meanwhile, the quick fusing in the case of medium-rate overcurrent is realized, and the damage of rear-end facilities caused by continuous overcurrent is prevented.

Description

Fuse for accelerating medium-multiplying power overcurrent fusing speed

Technical Field

The utility model relates to the field of fuses, in particular to a fuse for accelerating the medium-rate overcurrent fusing speed.

Background

At present, the lithium battery industry mainly adopts the matching combination of a relay and a fuse to protect, and when a large current short circuit occurs, the fuse is used for overcurrent fusing protection; the non-current abnormality mainly depends on a detection signal, and after the detection signal is judged by a battery management system, a relay is triggered to disconnect an abnormal loop. However, when the existing lithium battery system selects the fuse, the temperature rise requirement of high-current charge and discharge and the pulse current problem during high-capacity output need to be considered, and the specification of the fuse is generally larger, for example, the short-circuit protection current is selected to be larger than 3kA, and when the current which is smaller than 5 times of rated current occurs, the fuse cannot act in time, so that the rear-end circuit board or the lithium battery is damaged.

The phenomenon of early fusing of abnormal overcurrent usually occurs in the existing fuse, mainly in that the selected specification is smaller, but after the specification is larger, the fuse cannot be protected in time in the overcurrent state of the medium multiplying power.

Disclosure of utility model

In view of the above-mentioned drawbacks of the prior art, an object of the present utility model is to provide a fuse with a high medium-rate overcurrent fusing speed, which can be fused in time to provide an open-circuit protection in the medium-rate overcurrent state.

In order to achieve the above object, the present utility model provides a fuse for accelerating a medium-rate overcurrent fusing speed, comprising a first terminal, a second terminal, and a first current-carrying device and a second current-carrying device connected in parallel between the first terminal and the second terminal;

the first current carrying device comprises at least one first melt connecting a first terminal and a second terminal;

The second current-carrying device comprises at least one medium-rate fast melting branch circuit connected with the first terminal and the second terminal;

The medium-rate quick melting branch comprises a second melt and a disconnecting device which are connected in series, and the disconnecting device disconnects the first melt and the second melt before the first melt when the medium-rate is over-current.

Further, the first melt and the second melt are fuses or fused pieces with narrow diameters.

Further, the first melt and the second melt are one of copper, silver, aluminum or copper-based alloy, silver-based alloy, aluminum-based alloy or copper-silver composite material.

Further, the first melt is one of copper, silver, aluminum or copper-based alloy, silver-based alloy, aluminum-based alloy or copper-silver composite material; the second melt is nickel.

Further, the breaking means comprises a low melting point metal.

Further, the breaking device further comprises a fluxing agent, and the fluxing agent is coated on the surface of the low-melting-point metal.

Further, the breaking device further comprises a heating device, and the heating device is started when the medium multiplying power overflows, so that the low-melting-point metal is actively heated to accelerate fusing of the low-melting-point metal.

Further, the melting point range of the low-melting point metal is 70-450 ℃.

Further, the breaking device further comprises a mechanical breaking device, wherein the mechanical breaking device is arranged close to the low-melting-point metal, and the mechanical breaking device is started when the medium multiplying power flows through, so that the low-melting-point metal is actively cut off.

Further, the mechanical breaking device is an elastic breaking mechanism, and the movable end of the elastic breaking mechanism is abutted against the low-melting-point metal and is in an energy storage state and used for cutting off the low-melting-point metal in an overcurrent softening state.

Further, the mechanical breaking device is a pyrotechnic explosion cutting mechanism, a cutter of the pyrotechnic explosion cutting mechanism is arranged on one side of the low-melting-point metal, and the pyrotechnic explosion cutting mechanism is started when the medium multiplying power overflows, so that the low-melting-point metal is actively cut off.

Further, the disconnection device comprises a conductor and a mechanical breaking device; the conductor and the second melt are connected in series and provided with a structural weakening point for mechanical breaking.

Further, the mechanical breaking device is a pyrotechnic explosion cutting mechanism, a cutter of the pyrotechnic explosion cutting mechanism is abutted against the conductor, and a control loop of the pyrotechnic explosion cutting mechanism is started when the medium multiplying power is overflowed, so that the conductor is actively cut off.

Further, the ratio of the bearing currents of the first melt of the first current carrying device to the bearing currents of the medium-rate fast melting branch of the second current carrying device is in the range of 5:1-1:5.

Further, the fuse further comprises a first shell, a first end cover, a second end cover, a first bonding pad and a second bonding pad;

The second current carrying device and the first current carrying device are mounted within the first housing;

Two ends of the second current carrying device and the first current carrying device are welded on the first bonding pad and the second bonding pad respectively;

The first end cover and the second end cover are lead-out electrodes of the fuse, and are fixed at two ends of the first shell and respectively and fixedly and electrically connected with the first bonding pad and the second bonding pad.

Further, the first housing is provided with a T-shaped cavity, and the disconnecting means extends to a convex part in the middle of the T-shaped cavity.

The utility model realizes the following technical effects:

The fuse adopts the combination of the first current-carrying breaking device and the second current-carrying breaking device, so that the maximum breaking capacity of the fuse is consistent with the breaking capacity of a structure without a breaking device in the second current-carrying; the fuse with larger nominal current can be selected to bear the capability of larger temporary large current when the whole machine works, and meanwhile, the quick fusing in the case of medium-multiplying power overcurrent is realized, so that the damage of rear-end facilities caused by continuous overcurrent is prevented.

The terminal voltage of the breaking device in the second current-carrying device at the breaking moment is only the impedance voltage drop of the first current-carrying device, and no arc is generated basically, so that arc extinguishing requirements and difficulties are avoided when the structure is designed, and only the withstand voltage is required to reach the standard, and the breaking device can be designed in a minimized manner.

Drawings

FIG. 1 is a functional block diagram of a fuse of the present utility model;

fig. 2 is a circuit diagram of a first embodiment of the present utility model;

FIG. 3 is a block diagram of a first embodiment of the present utility model;

FIG. 4 is a cross-sectional view of the product construction of the first embodiment of the utility model;

FIG. 5 is an enlarged view of a portion of FIG. 4;

FIG. 6 is a current-time fusing curve of the first embodiment of the present utility model;

FIG. 7 is a circuit diagram of a second embodiment of the present utility model;

FIG. 8 is a block diagram of a second embodiment of the present utility model;

FIG. 9 is a current-time fusing curve of a second embodiment of the present utility model;

fig. 10 is a circuit diagram of a third embodiment of the present utility model;

FIG. 11 is a product construction diagram of a third embodiment of the utility model;

FIG. 12 is a cross-sectional view of the product construction of a third embodiment of the utility model;

fig. 13 is a schematic view of the structure of the present utility model mechanically broken by an elastic breaking mechanism;

FIG. 14 is a schematic view of the structure of the utility model mechanically broken by a pyrotechnic explosion severing mechanism;

fig. 15 is a current-time fusing curve of a fuse employing a pyrotechnic blast severing mechanism.

Wherein: 1-a housing; 2-nickel straps; 3-a low melting point metal; 4-bonding pads; 5-end caps; 6-silver tape; 7-quartz sand; 8-heating plates; a 9-T-shaped cavity; 10-an elastic breaking mechanism; 11-a pyrotechnic explosion shutoff mechanism; 30-a temperature fuse; 32-an upper cover; 33-a lower cover; 34-fluxing agent; 80-heating means; 82-temperature fuse; 83-an upper cover; 84-bracket; 85-a lower cover; 100-a first current carrying device; 101-a first melt; 200-a second current carrying device; 201-a second melt; 202-disconnecting the device; 2021-low melting point metals; 2022-elastic breaking mechanism; 2023-conductor; 2024-pyrotechnic explosion shut-off mechanism.

Detailed Description

For further illustration of the various embodiments, the utility model is provided with the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments and together with the description, serve to explain the principles of the embodiments. With reference to these matters, one of ordinary skill in the art will understand other possible embodiments and advantages of the present utility model. The components in the figures are not drawn to scale and like reference numerals are generally used to designate like components.

The utility model will now be further described with reference to the drawings and detailed description.

As shown in fig. 1, the present utility model provides a fuse for accelerating a medium-rate overcurrent fusing speed, comprising a first terminal P1, a second terminal P2, and a first current-carrying device 100 and a second current-carrying device 200 connected in parallel between the first terminal P1 and the second terminal P2; the first current carrying device 100 comprises at least one first melt 101 connecting a first terminal and a second terminal; the second current-carrying device 200 includes at least one medium-rate fast-melting branch connecting the first terminal P1 and the second terminal P2; the medium-rate fast melting branch comprises a second melt 201 and a breaking device 202 which are connected in series, and the breaking device 202 breaks before the first melt 101 and the second melt 201 when the medium-rate flows.

In a specific implementation, different breaking devices 202 may be provided to achieve a fast fusing of the fuse in case of medium-rate overcurrent.

Example 1

As shown in fig. 2 to 6, the present utility model provides a fuse for accelerating the medium-rate overcurrent fusing speed, in this embodiment, the first melt 101 of the first current-carrying breaking device 100 is mainly selected from materials such as copper, silver, aluminum or copper-based alloy, silver-based alloy, aluminum-based alloy or copper-silver composite, the second current-carrying breaking device 200 breaks the device 202 to be a low-melting-point metal, the second melt 201 can be selected from materials such as copper, silver, aluminum or copper-based alloy, silver-based alloy, aluminum-based alloy or copper-silver composite, and more preferably, the second melt 201 is formed by connecting materials with high-resistance temperature coefficients such as nickel tape in series.

In fig. 2, ATCO1 and ATCO2 are low melting point metals, a second melt 201 is nickel strap, and ATCO1, melt 201, ATCO2 and melt 201 form two branches of a second current-carrying breaking device; the two first melts 101 form two branches of the first current-carrying breaking device. P1 and P2 are the leading-out ends of the fuse.

The silver/copper/silver copper composite material is used as the melt of a conventional fuse, has high melting point (copper is 1083 ℃ and silver is 960 ℃) and high conductivity, and compared with other low-melting-point melt materials with the same size, the prepared melt has large rated current, low resistance and low power consumption, and can easily meet the requirement of high breaking current capacity. And setting parallel structures of different quantities of melts according to the current-carrying requirement to form a first current-carrying breaking device.

The second melt of the second current-carrying breaking device is preferably nickel tape, and mainly utilizes the temperature rise characteristic of the high-resistance temperature coefficient of nickel in overcurrent to be combined with the low-temperature fusing characteristic of low-melting-point metal to form the fast fusing device in medium-multiplying power overcurrent, so that the response time in medium-multiplying power overcurrent can be accelerated when the requirements of low-multiplying power and high-multiplying power overcurrent fusing are met. The temperature coefficient of resistance of nickel is about 6900 ppm/DEG C, the temperature coefficient of resistance of silver/copper is about 4000 ppm/DEG C, under the overcurrent state, nickel generates heat due to self resistivity, the temperature is raised, the self resistance is increased, and the change range is larger than that of silver/copper materials. The low-melting point metal is a metal with a melting point of 70-450 ℃ and an alloy thereof, and generally consists of Bi, sn, pb, in and other low-melting point metal elements. When overcurrent is caused at low multiplying power, the temperature rise of the nickel strap is small, the temperature rise superposition of the nickel strap is not obvious, and the fusing time of the nickel strap is equivalent to that of a conventional fuse; when the medium multiplying power overflows, the temperature rise of the nickel strap enters a jump zone, the nickel strap is quickly heated, heat is transferred to low-melting-point metal, the low-melting-point metal is fused, the current multiplying power is loaded on a first current-carrying breaking device, the first current-carrying breaking device is quickly fused, and the whole safety cutting is realized; when the high-rate overcurrent occurs, the temperature rise response speed of the nickel strap is lower than that of the low-melting-point metal, the low-melting-point metal is more influenced by the low-melting-point characteristic and the internal resistance of the low-melting-point metal, the current rises, the low-melting-point metal heats due to the internal resistance, the low-melting-point metal can be rapidly cut off due to the low melting point, and the response time of the low-melting-point metal is equivalent to that of the first current-carrying breaking device. In this application, the melting point range of the preferred low melting point metal is 100℃to 250 ℃.

The high-resistance temperature coefficient material is combined with the low-melting point metal material, the temperature of the material with the high-resistance temperature coefficient, which is overflowed at the medium multiplying power, is increased to be used as the melting heat of the low-melting point metal, so that the medium-multiplying power fast melting branch is melted, the current is carried at the current carrying breaking and current carrying multiplying power, and the melting response time is shortened. When the medium multiplying power overflows, the device can respond in advance, and damage to back-end facilities caused by continuous overcurrent is prevented.

In this embodiment, the first current-carrying breaking device is provided with two groups of current-carrying breaking branches. The silver tape 6 is connected between the end caps 5 as a first melt (first melt 101 in fig. 2) of the first current-carrying breaking device. In a specific application, different quantities or cross sections of first melts can be arranged according to current-carrying requirements to be connected in parallel so as to serve as a first current-carrying breaking device.

In this embodiment, the second current-carrying breaking device is provided with two groups of medium-rate fast-melting branches. The medium-rate fast melting branch consists of a nickel strip 2 (corresponding to the second melt 201 in fig. 2) and a low-melting metal 3 (corresponding to ATCO1 and ATCO2 in fig. 2) which are connected in series.

As shown in fig. 3 and 5, the surface of the low melting point metal 3 is coated with a fluxing agent 34, and is encapsulated by an upper cover 32 and a lower cover 33 to form a temperature fuse 30.

In this embodiment, two ends of the low melting point metal 3 are respectively connected to two sections of nickel straps 2, and the other ends of the two sections of nickel straps 2 are respectively connected to two bonding pads 4. In a specific application, the low melting point metal 3 may also be formed by being connected with a section of nickel strap 2.

In a specific application, nickel strips 2 and temperature fuses 30 with different numbers or cross sections can be arranged according to current-carrying requirements to serve as second current-carrying breaking devices.

The first current-carrying breaking device and the second current-carrying breaking device are welded on the welding pad 4 in a spot welding mode to form a parallel whole, and then are arranged in the shell 1. The housing 1 is made of a high-strength pressure-resistant insulating material such as ceramic. The two ends of the shell 1 are provided with end covers 5, and the end covers 5 and the welding pads 4 can be fixedly connected through screws, spot welding and the like, so that the electrodes of the fuse are led out.

In order to ensure that the first current-carrying breaking device and the second current-carrying breaking device are fused normally and prevent abnormal flashover, quartz sand 7 is filled at the periphery of the first melt and the second melt in the shell 1.

The temperature coefficient of resistance of nickel is about 6900 ppm/DEG C, the temperature coefficient of resistance of silver/copper is about 4000 ppm/DEG C, under the overcurrent state, nickel generates heat due to self resistivity, the temperature is raised, the self resistance is increased, and the change range is larger than that of silver/copper materials. The low-melting point metal is a metal with a melting point of 70-450 ℃ and an alloy thereof, and generally consists of Bi, sn, pb, in and other low-melting point metal elements.

The current-time fusing curve of the embodiment is shown in fig. 6, curve 1 is a fusing curve of a conventional silver tape as a melt, after the specification is selected to be large, the low-multiplying power overcurrent current-carrying requirement is met, and for medium-multiplying power overcurrent, the pre-arc response time is also delayed integrally, so that damage to a back-end facility due to continuous overcurrent can be caused. Curve 2 is an example of a current-time fusing curve of 400A in the embodiment, and when the current-time fusing curve is smaller than 1.2kA in low-rate overcurrent, the temperature rise of the nickel strap is not obvious due to small temperature rise, and the fusing time is equivalent to that of a conventional fuse; when the medium-rate overcurrent is carried out, the temperature rise of the nickel strap enters a jump zone, the nickel strap is quickly heated, heat is transferred to low-melting-point metal, the low-melting-point metal is fused, the current multiplying power is loaded on the first current-carrying breaking device, the first current-carrying breaking device is quickly fused, and the whole safety cutting is realized; when the high-rate overcurrent occurs, the temperature rise response rate of the nickel strap is higher than 10kA and is lower than that of the low-melting-point metal, more, the low-melting-point metal is achieved by the low-melting-point characteristic and the internal resistance of the low-melting-point metal, the current rises, the low-melting-point metal heats due to the internal resistance, the low-melting-point metal can be rapidly cut off due to the low melting point, and the response time of the low-melting-point metal is equivalent to that of the first current-carrying breaking device.

In summary, the fuse in this embodiment adopts the combination of the first current-carrying breaking device and the second current-carrying breaking device, and has the following technical effects:

1. The terminal voltage of the breaking device in the second current-carrying device at the breaking moment is only the impedance voltage drop of the first current-carrying device, and no arc is generated basically, so that arc extinguishing requirements and difficulties are avoided when the structure is designed, and only the withstand voltage is required to reach the standard, and the breaking device can be designed in a minimized manner.

2. The maximum breaking capacity of the fuse is ensured to be consistent with the breaking capacity of the structure without the breaking device in the second current carrying.

3. The fuse with larger nominal current can be selected to bear the capability of larger temporary large current when the whole machine works, and meanwhile, the quick fusing in the case of medium-multiplying power overcurrent is realized, so that the damage of rear-end facilities caused by continuous overcurrent is prevented.

Example 2

As shown in fig. 7, based on embodiment 1, the fuse may further be added with a self-thermal protection heater PTC, and a controlled function is realized in combination with detection signals of overcurrent detection and overvoltage detection. When the system detects an overcurrent signal, the heater loop is triggered to be conducted, the heater PTC starts to work and generate heat, heat is provided for ATCO1 and ATCO2, the ATCO1 and the ATCO2 are heated and fused, namely, the second current carrying breaking device is disconnected, the current is loaded on the first current carrying breaking device 100 in multiplying power, the temperature rise of the first melt 101 is increased, the loop is rapidly cut off, meanwhile, the heater PTC continuously works, the ATCO3 is heated and fused, the heater loop is cut off, and the work is stopped.

Fig. 8 shows an example of a product corresponding to fig. 7. Wherein, the heater PTC corresponds to the heating plate 8; the first melt 101 corresponds to the silver tape 6; ATCO1 and ATCO2 correspond to the low melting point metal 3; ATCO3 corresponds to thermal fuse 82.

In the present embodiment, the heating device 80 is composed of a heating plate 8 and a temperature fuse 82 connected in series, and is packaged together with the low melting point metals 3 of the two branches through an upper cover 83, a lower cover 85, and a bracket 84. The thermal fuse 82 continuously operates at a medium rate current to heat up and fuse, thereby avoiding that the heating device 80 continuously operates after the fuse blows.

Specifically, the heating plate 8 is disposed between two low-melting-point metals 3 of the second current-carrying breaking device and is fixed by the bracket 84, and meanwhile, the low-melting-point metals 3 of the two branches are fixed on two sides of the heating plate 8 by the upper cover 83, the lower cover 85 and the bracket 84, so that the heating plate 8 is ensured to uniformly heat the low-melting-point metals 3 of the two branches, the low-melting-point metals 3 of the two branches are fused, the current multiple is loaded on the first current-carrying breaking device, the first current-carrying breaking device is fused quickly, and the safety cutting is integrally realized.

The current-time fusing curve of this example is shown in fig. 9, wherein curve 1 is a fusing curve of a conventional silver tape as a melt; curve 2 is an example of a current-time fusing curve of 400A of the present embodiment, where the first inflection point (left inflection point) indicates that the heating device is activated at a lower current, the protection response time is shortened by passive fusing of the lower melting point metal, and the second inflection point (right inflection point) indicates that the heating device is activated at a higher current, and the protection response time is further shortened; the two inflection points of the dotted line represent different starting currents, the starting current is large, the response breaking speed is faster, and the response breaking time is shorter. When the low-rate overcurrent is less than 1.2kA, the temperature rise of the nickel strap is not obvious due to small temperature rise, and the fusing time of the nickel strap is equivalent to that of a conventional fuse; when the medium-rate overcurrent occurs, the low-melting-point metal is directly heated by a heater to fuse, the current is loaded on the first current-carrying breaking device in a multiplying power mode, and the first current-carrying breaking device is quickly fused, so that the safety cutting is integrally realized; when the high-rate overcurrent occurs, the temperature rise response rate of the nickel strap and the heating of the heater are higher than 10kA and do not act on the low-melting-point metal, more, the low-melting-point metal is achieved by the low-melting-point characteristic and the internal resistance of the low-melting-point metal, the current rises, the low-melting-point metal heats due to the internal resistance, the low-melting-point metal can be rapidly cut off due to the low melting point, and the response time of the low-melting-point metal is equivalent to that of the first current-carrying breaking device.

In a specific implementation, the distribution of the bearing current of each current-carrying breaking branch can be regulated by adjusting the number of branches or the wire diameter of the melt. Preferably, the ratio of the bearing current of the current-carrying breaking branch of the first current-carrying breaking device to the bearing current of the medium-rate fast-melting branch of the second current-carrying breaking device is generally set to be 5:1 to 1: 5. Preferred values include 3:1, 2:1, 1:1, 1:2 and 1:3, etc.

Example 3

As shown in fig. 10 to 12, the housing 1 of the fuse may be provided with a T-shaped cavity 9 so as to extend the temperature fuse 30 or the low melting point metal 3 of the second current-carrying breaking device to a convex portion in the middle of the T-shaped cavity. In this configuration, the temperature fuse 30 is kept at a distance from the other melt, and its melting is not or less affected by the temperature rise of the other melt, and sufficient space is provided for providing a mechanical breaking device.

In order to realize the rapid breaking of the second current-carrying breaking device, a mechanical breaking device can be used for mechanical breaking.

Example 4

In the present embodiment, the breaking means includes a low melting point metal 2021 and an elastic breaking mechanism 2022 as mechanical breaking means, as shown in fig. 13. In this embodiment, one end of the elastic breaking mechanism 2022 is fixed (e.g. fixed on the housing), and the other end abuts against the low-melting metal 2021, so that the whole elastic breaking mechanism is in an energy storage state. When the strength of the low-melting-point metal heated and softened structure is reduced, the structural strength of the low-melting-point metal heated and softened structure cannot bear the elasticity applied by the elasticity breaking mechanism, so that the elasticity breaking mechanism releases energy storage to break the low-melting-point metal. After breaking, sufficient safe spacing and electrical insulation strength are formed at the break points.

Example 5

In this embodiment, the breaking means includes a conductor 2023 and a pyrotechnic explosion breaking mechanism 2024 as a mechanical breaking means, as shown in fig. 14. Pyrotechnic explosion breaking mechanisms are commonly used in circuit breakers. Structural weakening points in the form of narrow diameters and the like are arranged on a main loop electrode of the circuit breaker, and the pyrotechnic explosion cutting mechanism acts to break the structural weakening points after receiving an instruction. When the pyrotechnic explosion cutting mechanism receives the command action, the piston acts on the narrow diameter under the pushing of the explosive airflow to break the main loop electrode, and the breaking point can be ensured to have enough safety distance and electric insulation strength. Since the pyrotechnic explosion cutting mechanism 2024 has a large impact force and a high breaking capacity, the conductor 2023 may be a copper tape or an aluminum tape with a narrow diameter (which is not fused when the medium-rate is excessive), or may be a low-melting-point metal (which is fused when the medium-rate is excessive). Similarly, the low-melting point metal is also a structural weakening point on the loop, and when the structural strength of the low-melting point metal is reduced, the low-melting point metal can be broken when the pyrotechnic explosion cutting mechanism 2024 acts, and the sufficient safety distance and electrical insulation strength can be ensured to be formed at the breaking point. The current-time fusing curve of the embodiment is shown in fig. 15, wherein curve 1 is a fusing curve of a conventional silver tape as a melt, and curve 2 is an example of a current-time fusing curve using a pyrotechnic explosion cutting mechanism; the first inflection point (left inflection point) indicates that the pyrotechnic explosion cutting mechanism is started at a lower current, the protection response time is shortened by passive fusing of the metal with a lower melting point, the second inflection point (right inflection point) indicates that the pyrotechnic explosion cutting mechanism is started at a higher current, the protection response time is further shortened, and compared with the technical scheme adopting the heating device in the embodiment 2, the technical scheme adopting the pyrotechnic explosion cutting mechanism is faster in fusing speed and shorter in protection response time; the two inflection points of the dotted line represent different starting currents, the starting current is large, the response breaking speed is faster, and the response breaking time is shorter.

In summary, the fuse in the above embodiment has the following technical effects:

1. When the breaking means in the second current carrying means are added with pyrotechnic explosion breaking means or heating means, a rated overcurrent protection function can be achieved.

2. When the breaking device in the second current-carrying device is added with a pyrotechnic explosion breaking mechanism or a heating device, if the detecting circuit fails or the ignition voltage input line or the heating current input line is broken accidentally, the fuse still has the functions of the basic fuse, such as overload protection breaking and maximum capacity safety breaking of short-circuit current.

While the utility model has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the utility model as defined by the appended claims.

Claims (16)

1. A fuse for accelerating the medium-rate overcurrent fusing speed is characterized in that: the device comprises a first terminal, a second terminal, a first current-carrying device and a second current-carrying device which are connected in parallel between the first terminal and the second terminal;

the first current carrying device comprises at least one first melt connecting a first terminal and a second terminal;

The second current-carrying device comprises at least one medium-rate fast melting branch circuit connected with the first terminal and the second terminal;

The medium-rate quick melting branch comprises a second melt and a disconnecting device which are connected in series, and the disconnecting device disconnects the first melt and the second melt before the first melt when the medium-rate is over-current.

2. The medium rate over-current fusing speed accelerating fuse of claim 1, wherein: the first melt and the second melt are fuse wires or fuse pieces with narrow diameters.

3. The medium rate over-current fusing speed accelerating fuse of claim 2, wherein: the first melt and the second melt are one of copper, silver, aluminum or copper-based alloy, silver-based alloy, aluminum-based alloy or copper-silver composite material.

4. The medium rate over-current fusing speed accelerating fuse of claim 2, wherein: the first melt is one of copper, silver, aluminum or copper-based alloy, silver-based alloy, aluminum-based alloy or copper-silver composite material; the second melt is nickel.

5. The medium rate over-current fusing speed accelerating fuse of claim 1, wherein: the disconnect device comprises a low melting point metal.

6. The medium rate over-current fusing speed accelerating fuse of claim 5, wherein: the breaking device also comprises a fluxing agent, wherein the fluxing agent is coated on the surface of the low-melting-point metal.

7. The medium rate over-current fusing speeding-up fuse of claim 6, wherein: the breaking device further comprises a heating device which is started when the medium multiplying power overflows, so that the low-melting-point metal is actively heated to accelerate fusing of the low-melting-point metal.

8. The medium rate over-current fusing speed accelerating fuse of claim 5, wherein: the melting point range of the low-melting point metal is 70-450 ℃.

9. The medium rate over-current fusing speed accelerating fuse of claim 5, wherein: the breaking device further comprises a mechanical breaking device, wherein the mechanical breaking device is arranged close to the low-melting-point metal, and the mechanical breaking device is started when the medium multiplying power flows through the device, so that the low-melting-point metal is actively cut off.

10. The medium rate over-current fusing speeding-up fuse of claim 9, wherein: the mechanical breaking device is an elastic breaking mechanism, and the movable end of the elastic breaking mechanism is in contact with the low-melting-point metal and is in an energy storage state and used for cutting off the low-melting-point metal in an overcurrent softening state.

11. The medium rate over-current fusing speeding-up fuse of claim 9, wherein: the mechanical breaking device is a pyrotechnic explosion cutting mechanism, a cutter of the pyrotechnic explosion cutting mechanism is arranged on one side of the low-melting-point metal, and the pyrotechnic explosion cutting mechanism is started when the medium multiplying power flows excessively.

12. The medium rate over-current fusing speed accelerating fuse of claim 1, wherein: the disconnecting device comprises a conductor and a mechanical punching device; the conductor and the second melt are connected in series and provided with a structural weakening point for mechanical breaking.

13. The medium rate over-current fusing speeding-up fuse of claim 12, wherein: the mechanical breaking device is a pyrotechnic explosion cutting mechanism, a cutter of the pyrotechnic explosion cutting mechanism is abutted against the conductor, and a control loop of the pyrotechnic explosion cutting mechanism is started when the medium multiplying power is overflowed, so that the conductor is actively cut off.

14. The medium rate over-current fusing speed accelerating fuse of claim 1, wherein: the ratio of the bearing currents of the first melt of the first current carrying device to the bearing current of the medium-rate fast melting branch of the second current carrying device ranges from 5:1 to 1:5.

15. The medium rate over-current fusing speed accelerating fuse of claim 1, wherein: the fuse further comprises a first shell, a first end cover, a second end cover, a first bonding pad and a second bonding pad;

The second current carrying device and the first current carrying device are mounted within the first housing;

Two ends of the second current carrying device and the first current carrying device are welded on the first bonding pad and the second bonding pad respectively;

The first end cover and the second end cover are lead-out electrodes of the fuse, and are fixed at two ends of the first shell and respectively and fixedly and electrically connected with the first bonding pad and the second bonding pad.

16. The medium rate over-current fusing speeding-up fuse of claim 15, wherein: the first housing is provided with a T-shaped cavity, and the disconnecting means extends to a convex part in the middle of the T-shaped cavity.