JP6435105B2 - Hybrid substrate fuse element - Google Patents

Description

  The present invention relates to a substrate fuse element formed by forming a conductive thin film on the surface of a substrate having electrical insulation.

  Conventionally, this type of substrate fuse element includes, for example, one used for a power fuse disclosed in Patent Document 1 and one used for a fuse link disclosed in Patent Document 2.

  The substrate fuse element used for the power fuse disclosed in Patent Document 1 is formed by laminating a conductive film on a ceramic substrate by a printing method, and includes a plurality of heat radiation portions having a large number of layers and a plurality of layers having a small number of layers. The blocking portion is integrally formed continuously. The blocking part is configured by arranging a plurality of narrow parts in parallel and further arranging them in series. The interruption | blocking part which comprised such a thing may be comprised so that what was formed so that an electric current-fusing time characteristic may differ may be continuously connected on the same ceramic substrate.

  Moreover, the substrate fuse element used for the fuse link disclosed by patent document 2 consists of the pattern of the electroconductive thin film formed in the surface of an insulating board | substrate. The pattern of the conductive thin film is a pattern in which a plurality of blocking sections having narrow blocking bands arranged in parallel are further arranged periodically and alternately in series via a connecting band, and connected in series.

JP 2012-227077 A Japanese Patent No. 5116119

  However, each of the above-mentioned conventional substrate fuse elements disclosed in Patent Document 1 and Patent Document 2 shows a good result for AC interruption that interrupts AC current, but is satisfactory for DC interruption that interrupts DC current. The result is not obtained. In recent years, electric vehicles using electric motors as a power source have been developed due to increasing interest in global environmental problems and resource constraints. A DC system is used for the power source of the electric vehicle. Therefore, it has sufficient energization capacity, can cut off the short-circuit current at the time of an accident without any abnormalities, and can also perform predetermined fusing for overcurrent exceeding the rated current There is a need for a fuse that has time-current characteristics and can reliably protect a DC system.

The present invention has been made to solve such problems,
A rectangular ceramic substrate having electrical insulation;
It is composed of a conductive thin film formed by printing and baking copper paste on the surface of the substrate,
Conductive thin film
A pair of current-carrying portions that are arranged at both ends of the substrate and have a rectangular shape that is slightly shorter than the width of the substrate and formed to a first thickness;
A plurality of narrow portions whose cross-sectional area is narrowed by removing the conductive thin film in a rectangular window shape are arranged electrically in parallel in the width direction of the substrate, and the parallel blocking portions are thinner than the first thickness. 2 is formed in a strip shape, and the parallel blocking portion is electrically arranged in series alternately through the heat dissipation portions formed in a strip shape having the first thickness. A large current interrupting portion having a rectangular shape having substantially the same width as the energizing portion and having one end connected to one energizing portion, wherein the parallel breaking point is set to 32 and the series breaking point is set to 10 ;
One end is connected to the other end of the large current energization unit, and the relay energization unit has a rectangular shape with the same width as the energization unit and has a first thickness,
Center in the width direction is arranged connected to the other conductive portion ties the other end to the other end of the matching end by the relay energizing portion at the center in the width direction of the substrate, by stretching the arc generated at the time of shielding sectional Formed in a plate shape to increase the arc voltage, both the number of series interruption points and the number of parallel interruption points are set to one, and overcurrent that is smaller than the accident current that is interrupted by the large current interruption part and larger than the rated current is interrupted. It is composed of a small current interrupting part connected in series with a large current interrupting part that interrupts before the part,
The resistance value of the small current interrupting unit is set to be higher by a predetermined ratio than the resistance value of the large current interrupting unit so that the small current interrupting unit interrupts the overcurrent before the large current interrupting unit,
The current density at the minimum cross-sectional area of the narrow part is set to be a predetermined percentage higher than the current density at the minimum cross-sectional area of the small current interrupting part so that the large current interrupting part is responsible for interrupting the accident current,
And configure <br/> hybrid substrate fuse element minimum sectional area portion has a conductive thin film meat beauty constituting the capacitive current interruption portion.

  According to this configuration, an overcurrent larger than the rated current is interrupted prior to the large current interrupter by the small current interrupter connected in series with the large current interrupter, and an accident current larger than the overcurrent is large. It is interrupted by the current interrupting part or by both the large current interrupting part and the small current interrupting part. For this reason, there is provided a fuse that has a sufficient current-carrying capacity, can cut off a short-circuit current at the time of an accident without abnormality, and can cut off an overcurrent exceeding a rated current, and can reliably protect a DC system.

  According to this configuration, the resistance value of the small current interrupting part is set to be higher by a predetermined ratio than the resistance value of the large current interrupting part, so that a predetermined fusing time-current characteristic can be obtained with respect to the overcurrent, and The current interrupting part is surely fused before the large current interrupting part to interrupt the overcurrent. In addition, the current density in the minimum cross-sectional area of the narrow part is set to be a predetermined ratio higher than the current density in the minimum cross-sectional area of the small current interrupting part, so that the occurrence of an accident current that suddenly increases the current value The narrow portion takes the lead and melts and ignites, and the current is interrupted quickly in the large current interrupting portion, and the fault current is reliably limited and interrupted.

  According to this configuration, the heat generation amount of the constricted minimum cross-sectional area is high in the small current interrupting portion, and the fusing time of the small current interrupting portion at the time of overcurrent occurrence is the same as that in the small current interrupting portion formed in a plate shape. It can be controlled by the formation position of the minimum cross-sectional area. That is, when the position of the minimum cross-sectional area in the small current interrupting part approaches the center of the fuse, a heat distribution that makes it difficult for the heat in the fuse to escape is formed, and the ignition temperature is quickly reached in the high temperature region of the small current interrupting part. The fusing time of the small current interrupting part tends to be shortened. In addition, when the position where the minimum cross-sectional area portion is formed in the small current interrupting portion is away from the center of the fuse, a heat distribution in which heat in the fuse is easily dissipated is formed, and the high temperature region of the small current interrupting portion reaches the ignition temperature. It takes time, and the fusing time of the small current interrupting part tends to be long.

  Further, the present invention is characterized in that a low melting point metal is formed on a part of the surface of the conductive thin film constituting the small current interrupting portion.

  According to this configuration, the portion of the conductive thin film in which the low-melting point metal is formed is alloyed with the low-melting point metal at the time of melting and the melting point is lowered. It can be controlled by the type of the low melting point metal and the formation position of the low melting point metal in the small current interrupting portion.

  In addition, the present invention is characterized in that the conductive thin film constituting the small current interrupting portion has a constant thickness and is thinly and widely formed on the surface of the substrate.

  According to this configuration, the heat generated in the conductive thin film constituting the small current interrupting portion is quickly transmitted to the substrate, and the heat dissipation of the small current interrupting portion is improved. For this reason, the fusing time of the small current interrupting part becomes longer for the overcurrent in the small current region, and for the accident current in the large current region, the current conduction is performed while the heat conduction to the substrate is adiabatic. Therefore, the fusing time characteristic of the fuse element becomes a quick response type.

  Further, the present invention is characterized in that the small current interrupting part is formed at the end of the substrate close to the fuse terminal.

  According to this configuration, heat generated in the conductive thin film constituting the small current interrupting part is quickly transmitted to the fuse terminal, and the heat dissipation of the small current interrupting part is improved. For this reason, even with this configuration, the fusing time of the small current interrupting portion becomes longer with respect to the overcurrent in the small current region, and the fusing time characteristics of the fuse element are made rapid.

  According to the present invention, there is provided a fuse that has a sufficient current-carrying capacity, can cut off a short-circuit current at the time of an accident without any abnormality, and can also cut off an overcurrent exceeding a rated current, thereby reliably protecting a DC system. The

(A) is a top view which shows the hybrid substrate fuse element by one Embodiment of this invention, (b) is a partially expanded view. (A) is a partially broken plan view of a fuse link provided with a hybrid substrate fuse element according to an embodiment, and (b) is a partially broken side view. It is a test circuit diagram of the direct current | flow interruption test performed about the fuse link provided with the hybrid substrate fuse element by one Embodiment. The test result of said direct current | flow interruption test is shown, (a) is a breaking voltage waveform, (b) is a graph which shows a breaking current waveform. It is the table | surface which put together the said DC interruption | blocking test result. It is a graph which shows the fusing time test result done about the fuse link provided with the hybrid fuse element by one embodiment.

  Next, an embodiment in which the hybrid substrate fuse element according to the present invention is applied to a fuse for protecting a drive circuit in an electric vehicle will be described.

  FIG. 1A is a plan view showing a hybrid substrate fuse element 1 having a rated voltage of 450 V and a rated current of 40 A according to this embodiment.

  The hybrid substrate fuse element 1 is composed of a conductive thin film 3 formed on a ceramic substrate 2 having electrical insulation. In the present embodiment, the ceramic substrate 2 has outer dimensions of a thickness of 1 mm, a width of 9 mm, and a length of 40 mm. The conductive thin film 3 is formed in a pattern shown in the figure by printing a copper paste on the surface of the ceramic substrate 2 and firing, and a large current interrupting part (hereinafter referred to as a P part) having different fusing characteristics and interrupting characteristics. 4 and a small current interrupting part (hereinafter referred to as I part) 5 are connected in series via an energizing part 6. The thickness of the energizing portion 6 is set to 100 μm.

  FIG. 2B shows a partially enlarged view of the P portion 4. In the present embodiment, the P portion 4 has 32 narrow portions 4 a having a narrow cross-sectional area arranged electrically in parallel. The parallel blocking part 4b is formed. The P section 4 is configured by further arranging ten parallel blocking sections 4b electrically in series via the heat radiating section 4c. Therefore, the number of series interruption points (S) of the P section 4 is 10S, and the number of parallel interruption points (P) is 32P. The thickness of the parallel blocking portion 4b is set to 40 μm, and is formed thinner than the thickness of 100 μm of the heat radiating portion 4c.

  The I part 5 is 25 μm thick and is formed in a plate shape having a large length L in the energizing direction, and an overcurrent that is smaller than the accident current blocked by the P part 4 and larger than the rated current will be described later. Shut off before P part 4. The reason why the length L in the energization direction is large is that it is considered that a method of extending the arc generated at the time of interruption and increasing the arc voltage is effective also in the interruption of direct current. The number of series interruption points (S) of the I part 5 is 1S, and the number of parallel interruption points (P) is 1P. The I portion 5 does not have a simple rectangular shape in plan view, and has a butterfly shape with a constricted minimum cross-sectional area portion 5a. Further, the I portion 5 has a constant thickness and is thinly and widely formed on the surface of the ceramic substrate 2. The constriction is formed by reducing the width w2 of the minimum cross-sectional area 5a by a predetermined ratio from the rectangular width w1, and the amount corresponding to the cross-sectional area reduced by the constriction, that is, the amount of increase in the resistance value, The peripheral portion has a wide width w1. In the present embodiment, the width w1 is set to 6 mm and the width w2 is set to 5.4 mm.

  The resistance value of the I part 5 is set to be higher by a predetermined ratio than the resistance value of the P part 4 so that the I part 5 interrupts the overcurrent before the P part 4. In the present embodiment, the resistance value ratio between the P portion 4 and the I portion 5 is set to 2: 3. Moreover, the current density in the minimum cross-sectional area part of the narrow part 4a is set higher by a predetermined ratio than the current density in the minimum cross-sectional area part 5a of the I part 5 so that the P part 4 is responsible for interrupting the accident current. In the present embodiment, the current density ratio between the P portion 4 and the I portion 5 is set to 1.3: 1.

  The hybrid substrate fuse element 1 described above constitutes a fuse link 8 by being housed in a ceramic cylinder 7 as shown in FIG. 2A is a partially broken plan view of the fuse link 8, and FIG. 2B is a partially broken side view. The ceramic cylinder 7 has a hollow cylindrical shape with a diameter of 25 mm. The arc-extinguishing agent 9 is filled inside the ceramic cylinder 7 and both ends are closed with caps 10 and 10. In the hybrid substrate fuse element 1, fuse terminals 11 and 11 made of a copper plate are soldered to current-carrying parts 6 and 6 at both ends, and the fuse terminals 11 and 11 are press-fitted into insertion holes of the caps 10 and 10, respectively. It is accommodated inside the ceramic cylinder 7. Therefore, the I portion 5 in the hybrid substrate fuse element 1 is located at the end portion of the ceramic substrate 2 close to the one fuse terminal 11.

A DC interruption test was performed on the fuse link 8 configured as described above. The DC blocking test was conducted in the test circuit shown in FIG. 3, the combined capacitance charges the three capacitors C ₀ connected in series of 0.147F, by closing the switch SW, a test fuse (Test Fuse) The discharge current of the capacitor C ₀ was supplied to the fuse link 8. In the test fuse, an inductor L ₀ having an inductance of 0.394 mH and a resistor R ₀ having a DC resistance value of 223 mΩ are connected in series, and the recovery voltage after interruption is set to about 500V. With this test circuit, the fuse link 8 is supplied with a DC decay current having a specific current value of about 2200 A with a rise time of 2.0 ± 0.5 ms. The voltage Va generated in the test fuse at this time was measured, and the current Ia flowing through the test fuse was measured by the shunt resistance R _sh .

  4A and 4B show the results of the DC interruption test. FIG. 4A is a graph showing the interruption voltage waveform, and FIG. 4B is a graph showing the interruption current waveform. In these graphs, the horizontal axis represents time (ms), and the vertical axis represents voltage (Voltage) [V] and current (Current) [A]. In addition, a circle mark indicates the time when the switch SW of the test circuit was turned on, a triangle mark indicates when the hybrid substrate fuse element 1 starts blowing, and a ◇ mark indicates when the interruption is completed. ing.

  ○ At the time of fusing indicated by Δ mark about 1.808 ms after the charging time, the voltage is steep as shown in the cut-off voltage waveform graph of FIG. Is rising. The maximum voltage value (operating overvoltage) is 1313 V, the maximum current value (current limiting value) is 1456.8 A, and then the current decreases rapidly as shown in the graph of the breaking current waveform in FIG. It can be seen from each graph that the current interruption is completed when the ◇ mark is interrupted. Moreover, it is grasped | ascertained from the graph of a cutoff voltage waveform that the recovery voltage after interruption | blocking is about 500V. Since all the insulators of the fuse link 8 after being cut off have no apparent change or damage, it can be said that a good cut off has been performed. Further, the P portion 4 and the I portion 5 in the hybrid substrate fuse element 1 after being cut off are attached with the fluorite that is melted and solidified by the arc-extinguishing agent 9, so that the P portion 4 and the I portion as designed. It was confirmed that both of the parts 5 contributed to the interruption of the accident current.

FIG. 5 is a chart summarizing the results of the above-described blocking test. As shown in this chart, the prototype No. 40 of the rated current 40A used in this test was used. 1 fuse link 8 had a resistance value of 5.75 mΩ. Further, as described above, the operating overvoltage was 1313 V, and the current limiting value was 1456.8 A. In addition, the operation I ² t value corresponding to the current energy until the interruption is completed is 2179.8 A ² s, and the breakdown is a fusing I ² t value corresponding to the current energy until fusing is 1474.7 A ^2. s, the arc I ² t value corresponding to the current energy at the time of arc generation was 705.1 A ² s. In addition, the operation time until the interruption is completed is 3.824 ms, and the breakdown is as follows: the fusing time that is the time until fusing is 1.808 ms, and the arc time that is the time that the arc is generated is 2.016 ms. Met. In addition, the insulation resistance between the fuse terminals 11 and 11 after the interruption was 100 MΩ or more, and the quality of the interruption was determined to be good.

  Further, a fusing time test was also performed on the fuse link 8 of the present embodiment. This fusing time test was conducted according to the electrical standard No. of the Japan Automobile Engineering Association standard (JASO standard). D622-11 “Screw-clamped high-voltage fuse” was applied with the current specified, and the time until fusing was measured.

  FIG. 6 is a graph showing the fusing time test results. In the graph, the horizontal axis represents current (A) [A] and the vertical axis represents pre-arching time [s]. In addition, the fusing time characteristic line 21 connecting the plots marked with ◇ is the specified minimum time defined in the JASO standard for fuses with a rated current of 40A, and the fusing time characteristic line 22 connecting the plots marked with □ is a fuse with a rated current of 40A. The fusing time characteristic line 23 connecting the plot of the maximum time and Δ mark defined in the JASO standard is the prototype No. of the rated current 40A used in this test. 2 shows the fusing time of the fuse link 8 of No. 2.

  As understood from the graph, it is confirmed that the fusing time-current characteristic of the fuse link 8 according to the present embodiment is within the upper and lower limits of the fusing time characteristic required by the JASO standard. It was.

  According to the hybrid substrate fuse element 1 according to the present embodiment, an overcurrent larger than the rated current is interrupted prior to the P portion 4 by the I portion 5 connected in series to the P portion 4, An accident current larger than the current is interrupted by the P part 4 or by both the P part 4 and the I part 5. For this reason, the fuse link 8 is provided which has a sufficient current-carrying capacity, can cut off a short-circuit current at the time of an accident without any abnormality, can cut off an overcurrent exceeding the rated current, and can reliably protect a DC system. .

  In addition, according to the hybrid substrate fuse element 1 according to the present embodiment, the resistance value of the I portion 5 is set to be higher by a predetermined ratio than the resistance value of the P portion 4, so that a predetermined fusing time with respect to overcurrent is achieved. The current characteristic is obtained as shown in the graph of FIG. 6, and the I part 5 is surely fused before the P part 4 to cut off the overcurrent. In addition, the current density in the minimum cross-sectional area portion of the narrow portion 4a is set to be a predetermined ratio higher than the current density in the minimum cross-sectional area portion 5a of the I portion 5, thereby generating an accident current that rapidly increases in current value. Correspondingly, the narrow portion 4a takes the initiative to melt and ignite, and the current interruption is quickly performed in the P portion 4, and the accident current is surely limited and interrupted.

  Further, the heat generation amount of the constricted minimum cross-sectional area portion 5a is high in the I portion 5, and the fusing time of the I portion 5 when an overcurrent is generated is that of the minimum cross-sectional area portion 5a in the I portion 5 formed in a plate shape. It can be controlled by the forming position. That is, when the formation position of the minimum cross-sectional area portion 5a in the I portion 5 approaches the center of the fuse link 8, a heat distribution in which the heat in the fuse link 8 is difficult to escape is formed, and the high temperature region of the I portion 5 is rapidly increased in the ignition temperature. The melting time of the I part 5 tends to be shortened. Further, when the formation position of the minimum cross-sectional area portion 5a in the I portion 5 is away from the center of the fuse link 8, a heat distribution in which the heat in the fuse link 8 is easily dissipated is formed, and the high temperature region of the I portion 5 is ignited. It takes time to reach the temperature, and the fusing time of the I part 5 tends to be long.

  Further, since the I portion 5 has a constant thickness and is formed thin and wide on the surface of the ceramic substrate 2, heat generated in the conductive thin film 3 constituting the I portion 5 is quickly transmitted to the ceramic substrate 2. The heat dissipation of the I part 5 is improved. For this reason, the fusing time of the I part 5 becomes longer for the overcurrent in the small current region, and for the accident current in the large current region, the heat conduction to the ceramic substrate 2 is adiabatic and the current interruption is performed. To be made shorter. Therefore, the fusing time characteristic of the hybrid fuse element 1 is a rapid response type in which the fusing time characteristic line 23 rises as shown in the graph of FIG.

  Further, since the I part 5 is located at the end of the ceramic substrate 2 close to the fuse terminal 11, heat generated in the conductive thin film 3 constituting the I part 5 is quickly transmitted to the fuse terminal 11, and the I part 5 The heat dissipation is improved. For this reason, even with this configuration, the fusing time of the I portion 5 becomes longer with respect to the overcurrent in the small current region, and the fusing time characteristic of the hybrid fuse element 1 is made to be a rapid response type.

  In the above embodiment, a low melting point metal such as tin may be formed on a part of the surface of the conductive thin film 3 constituting the I portion 5. For example, the width direction surface of an appropriate portion of the I portion 5 is configured by performing tin plating in a slit shape. According to this configuration, since the portion of the conductive thin film 3 on which the low melting point metal is formed is alloyed with the low melting point metal at the time of melting and the melting point is lowered, the melting time of the I part 5 at the time of occurrence of overcurrent is It can be controlled by the type of the low melting point metal and the formation position of the low melting point metal in the I portion 5. For this reason, it is possible to change the material of the cylinder 7 from ceramic to inexpensive FRP or the like by shortening the fusing time of the I portion 5 by such control and suppressing the temperature rise of the cylinder 7 of the fuse link 8. become.

  In the above embodiment, the case where the hybrid substrate fuse element 1 according to this embodiment is used as a protective fuse for a drive circuit in an electric vehicle has been described. However, the present invention is not limited to such an application. For example, a DC power distribution system in a distributed power source such as a solar battery for protecting a charging device for a vehicle, protecting a large capacity system for power transmission and generation, or the like. The present invention can also be applied to fuses for protecting the semiconductor and for protecting the semiconductor. Furthermore, the present invention can be similarly applied to a train fuse having a high voltage / current and a DC fuse in a data center. Moreover, although the hybrid substrate fuse element 1 according to the present embodiment has been described as being applied to a DC interrupting fuse, it can be similarly applied to an AC interrupting fuse. Even when the present invention is applied to each of such fuses, the same effects as those of the above-described embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Hybrid substrate fuse element 2 ... Ceramic substrate 3 ... Conductive thin film 4 ... Large electric current interruption part (P part)
5 ... Small current interrupting part (I part)
6 ... Current-carrying part 7 ... Ceramic cylinder 8 ... Fuse link 9 ... Arc-extinguishing agent 10 ... Cap 11 ... Fuse terminal

Claims (4)

A rectangular ceramic substrate having electrical insulation;
It is composed of a conductive thin film formed by printing and baking a copper paste on the surface of the substrate,
The conductive thin film is
A pair of current-carrying portions that are arranged at both ends of the substrate and have a rectangular shape with a width slightly shorter than the width of the substrate and formed to a first thickness;
The conductive thin film is removed in the shape of a rectangular window so that a plurality of narrow portions whose cross-sectional areas are narrowed are arranged in parallel in the width direction of the substrate, and a parallel blocking portion is larger than the first thickness. The parallel blocking portion is electrically connected via the heat dissipation portions alternately formed in the strip shape having the first thickness. A large current arranged in series, having a parallel cut-off point of 32 and a series cut-off point of 10 and having a rectangular shape substantially the same width as the current-carrying part and having one end connected to one of the current-carrying parts A blocking section;
One end portion is connected to the other end portion of the large current energizing portion, and the relay energizing portion is formed in the first thickness with a rectangular shape having the same width as the energizing portion,
Arc center in the width direction leads the other end is arranged connected to the conductive portion of the other to the other end of the one end coincides with the width direction of the center of the substrate is the relay energizing unit, generated during barrier sectional Is formed in the shape of a plate that increases the arc voltage by extending the voltage, the number of series breaking points and the number of parallel breaking points are both set to one, and the overcurrent is smaller than the accident current that is interrupted by the large current breaking unit and larger than the rated current And a small current interrupting part connected in series to the large current interrupting part.
The resistance value of the small current interrupting part is set higher by a predetermined ratio than the resistance value of the large current interrupting part so that the small current interrupting part interrupts the overcurrent prior to the large current interrupting part,
The current density in the minimum cross-sectional area portion of the narrow portion is set to be a predetermined ratio higher than the current density in the minimum cross-sectional area portion of the small current interrupting portion so that the large current interrupting portion is responsible for interrupting the accident current,
It said hybrid substrate fuse element minimum sectional area portion constricted in the conductive thin film constituting the capacitive current interruption portion. 2. The hybrid substrate fuse element according to claim 1, wherein a low melting point metal is formed on a part of the surface of the conductive thin film constituting the small current interrupting portion. 3. The hybrid substrate fuse element according to claim 1, wherein the conductive thin film constituting the small current interrupting portion has a constant thickness and is formed thin and wide on the surface of the substrate. 4. . 4. The hybrid substrate fuse element according to claim 1, wherein the small current interrupting portion is formed at an end portion of the substrate close to a fuse terminal. 5.

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