JP2005026666A - Current limiting device and cut-off current interrupting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a current limiting device a cut-off current interrupting device using the same capable of suppressing the deterioration in the conduction performance after the current limiting operation. <P>SOLUTION: The device comprises a PTC element constituted of a pair of fused electrodes 2a and 2b fused to a PTC polymer 1 and to a PTC polymer arranged in opposition to the PTC 1 with a PTC polymer in between, respectively, a pair of terminal electrodes 3a and 3b arranged on the side and opposite side of the PTC polymer of the pair of fused electrodes, respectively, and adjacent to the pair of the fused electrodes, respectively; and pressure applying means 33, 34, 35a, and 35b for pressing the pair of terminal electrodes toward the side of the PTC element. At least one of the pair of fused electrodes is provided with a through-hole 20 formed therein, or is divided into two or more and arranged in a island-pattern. Consequently, the electrode area ratio, which is a ratio of the area of the surface of the PTC polymer to which the fused electrode is fused to the area of the surface of the fused electrode to which the PTC polymer is fused, is less than 1, and the surface of the terminal electrode adjacent to the fused electrode whose electrode area ratio is less than 1 on the side adjacent to the fused electrode is turned into a coarse one. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention includes a PTC element having a positive temperature coefficient (PTC) polymer having a positive resistance temperature characteristic and a pair of electrodes fused to the PTC polymer, and is used for limiting a short-circuit current. The present invention relates to a flow device and a current-limiting circuit breaker using the same.

  In a conventional current limiter, a PTC polymer portion having a positive resistance temperature characteristic composed of a polymer and a conductive substance mixed in the polymer, and a pair of electrodes (fused to the PTC polymer portion) A current limiting device comprising a PTC element comprising at least one electrode), wherein at least one hole is formed in the electrode, and pressure is applied to the electrode in a direction perpendicular to the surface of the PTC polymer portion. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 10-312911 (page 4-8, FIG. 1-14)

  The conventional current limiter is configured as described above, and an arc is generated between the PTC polymer part and the fusion electrode during the current limit, and the surface of the PTC polymer part is roughened by the heat of the arc. There has been a problem that the contact resistance (electrical resistance) between the polymer portion and the fused electrode is greatly increased, and the current-carrying performance of the current limiter is greatly reduced.

  The present invention has been made in order to solve the above-described problems of the prior art, and is a current limiter capable of suppressing a decrease in energization performance after a current limiting operation, and a current limiting interruption using the current limiter. An object is to provide an apparatus.

  The current limiting device according to the present invention includes a PTC element comprising a PTC polymer and a pair of fusion electrodes which are arranged opposite to each other with the PTC polymer interposed therebetween and fused to the PTC polymer, and the PTC polymer of the pair of fusion electrodes. A pair of terminal electrodes respectively disposed on the opposite side of the arrangement side and adjacent to the pair of fusion electrodes, and a pressing means for pressing the pair of terminal electrodes to the PTC element side, and the pair of fusion electrodes At least one fusion electrode among the electrodes has a through hole or is divided into a plurality of islands and arranged in an island shape, so that the area of the fusion surface with the fusion electrode of the PTC polymer is reduced. The electrode area ratio, which is the ratio of the area of the fused surface with the PTC polymer of the fused electrode, is smaller than 1 and the terminal electrode adjacent to the fused electrode with the electrode area ratio smaller than 1 is fused. Surface of the electrode adjacent side is what is roughened.

  A current limiting interrupter according to the present invention is a current limiting interrupter in which a current limiter having a pair of fused electrodes having different electrode area ratios and a switch for opening and closing an electric circuit are connected in series, A terminal electrode adjacent to the fused electrode having a larger electrode area ratio in the flow device is connected to the switch.

  Further, the current limiting device is a current limiting interrupter in which a current limiting device and a switch for opening and closing an electric circuit are connected in series, and the current limiting device is built in the switch.

  As described above, according to the present invention, a PTC element comprising a PTC polymer and a pair of fusion electrodes that are opposed to each other with the PTC polymer interposed therebetween and fused to the PTC polymer, and the pair of fusion electrodes. A pair of terminal electrodes respectively disposed on the opposite side of the PTC polymer arrangement side and adjacent to the pair of fusion electrodes, and a pressing means for pressing the pair of terminal electrodes toward the PTC element side, At least one fusion electrode among the fusion electrodes has a through-hole formed therein or is divided into a plurality of islands and arranged in an island shape, so that the fusion surface of the fusion electrode with the PTC polymer fusion electrode is formed. A terminal adjacent to the fused electrode having an electrode area ratio, which is a ratio of the area of the fused surface with the PTC polymer of the fused electrode to the area, smaller than 1, and the electrode area ratio is smaller than 1. Since the surface of the adhesive metal adjacent the side of the electrode is roughened, it is possible to suppress a decrease in power performance after current limiting.

  In addition, since the terminal electrode adjacent to the fusion electrode having the larger electrode area ratio in the current limiter is connected to the switch, high current-carrying performance of the current limiter can be obtained.

  In addition, the current limiting device is a current limiting breaker in which a current limiting device and a switch for opening and closing an electric circuit are connected in series, and the current limiting device is built in the switch, so that the current limiting interrupting device can be miniaturized. Can do.

Embodiment 1 FIG.
1 to 3 are diagrams for explaining the current limiter according to the first embodiment of the present invention. More specifically, FIG. 1 is an initial state (that is, the current limiting operation has been performed once). FIG. 2 is a plan view showing the configuration of the PTC element, and FIG. 3 is a current limiter after the current limiting operation (that is, the current limiting operation is performed at least once). It is sectional explanatory drawing which shows the structure of the principal part.

A plate-like PTC polymer 1 having two parallel principal surfaces, and a pair of fusion electrodes 2a and 2b (hereinafter represented by 2) fused to each principal surface of the PTC polymer 1 (thermal fusion). In other words, a PTC element is configured.
A pair of terminal electrodes 3a, 3b (hereinafter also represented by 3) are respectively arranged on the opposite side of the PTC polymer 1 arrangement side of the pair of fusion electrodes 2a, 2b, and the pair of fusion electrodes 2a, 2b, 2b are adjacent to each other.

  The PTC polymer 1 has a low electrical resistivity at room temperature (room temperature electrical resistivity), and exhibits a characteristic (positive resistance-temperature characteristic) in which the electrical resistivity rapidly increases at a high temperature. This characteristic is called a PTC characteristic. The PTC polymer 1 is made of a composite material in which a particulate conductive substance is kneaded with an electrically insulating polymer. The polymer is a resin such as polyethylene, polypropylene, or nylon, and the particulate conductive material is carbon black or metal particles such as tungsten. In such a case, the PTC characteristic is that when the temperature of the PTC polymer 1 exceeds the melting temperature (transition temperature) of the polymer due to a temperature rise such as exotherm, the volume of the polymer expands, and the amorphous portion (grain boundary of the polymer) It is thought that the particulate conductive substances existing in (part) are expressed by separating from each other. Specifically, for example, when the polymer is polyethylene, the transition temperature is about 130 ° C., and when this temperature is exceeded, for example, when the conductive material is carbon black, the electrical resistivity is 100 times. When the conductive material is tungsten, the electrical resistivity increases to about 10,000 times or more.

  The fusion electrodes 2a and 2b are, for example, a metal foil such as copper or nickel (for example, a thickness of about 20 to 70 μm) or a copper plate (for example, a thickness of about 150 μm or more) plated with nickel or silver. Is used, and the main surfaces of the fused electrodes 2 a and 2 b are fused to the main surface of the PTC polymer 1. Further, the fusion electrode 2 is formed with a through hole 20 having a shape as shown in FIG. 2, for example. By forming the through hole 20 in the fusion electrodes 2a and 2b in this way, the PTC polymer is formed. The fusion surface of the fusion electrodes 2a and 2b with the PTC polymer 1 with respect to the area of the fusion surface with the fusion electrode 2 (hereinafter also referred to simply as the fusion surface of the PTC polymer 1). Hereinafter, the electrode area ratio, which is simply the area ratio of the fusion electrodes 2a and 2b, sometimes referred to as the fusion surface of the fusion electrodes 2a and 2b, is smaller than 1. In the present embodiment, the main surface of the PTC polymer 1 is formed larger than the main surface of the fusion electrode 2. In the present invention, the area of the fusion surface of the PTC polymer 1 is the PTC polymer 1. This is not the total area of the main surface, but the area of the fusion surface of the PTC polymer 1 facing the main surfaces of the fusion electrodes 2a and 2b (the hatched portion in FIG. 2). The area of the fused surface of the fused electrodes 2a and 2b referred to in the present invention is the portion of the fused surface of the fused electrodes 2a and 2b facing the main surface of the PTC polymer 1 (hatched in FIG. 2). Part)), it refers to the area of the surface that is actually fused without including the area of the through hole 20.

  Further, the fused surface of the fused electrode 2 (both fused electrodes 2a and 2b in the present embodiment) having an electrode area ratio smaller than 1 has an average roughness of, for example, 5 to 30 μm by plating or blasting, for example. The rough surface is formed so as to have irregularities, that is, it is roughened, and the electrical contact resistance between the fusion electrodes 2a, 2b and the PTC polymer 1 is kept low. Here, the average roughness refers to the 6th revised edition of JSME Handbook for Mechanical Engineers published by the Japan Society of Mechanical Engineers. The 10-point average roughness described in 17-190.

  The terminal electrode 3 and the current introduction terminal 31 for supplying a current to the fusion electrode 2 through the terminal electrode 3 are, for example, copper plates plated with silver, tin, etc. Is about 1.5 mm and 2 mm, for example. The surface of the terminal electrode 3 adjacent to the fusion electrode 2 having an electrode area ratio smaller than 1 (both terminal electrodes 3a and 3b in the present embodiment) on the side adjacent to the fusion electrode 2 is average-roughed, for example, by blasting. Is roughened, that is, roughened so as to have, for example, irregularities of 5 to 20 μm. The fusion electrode 2, the terminal electrode 3, and the current introduction terminal 31 are electrically connected to each other. The terminal electrode 3 may be integrated with the current introduction terminal 31.

  In the present embodiment, since the number of contact points increases because the surface of the terminal electrode 3 adjacent to the fusion electrode 2 is roughened, the electrical connection between the terminal electrode 3 and the fusion electrode 2 is increased. The typical contact resistance is reduced compared to the case where the surface is not roughened (planar). As a result, energization performance is improved.

The insulating frame 32 is configured to introduce a current by a conductive gas generated by an arc generated between the PTC polymer 1 and the fusion electrode when a short-circuit current or an overcurrent flows to the PTC element and a current limiting operation occurs. In order to prevent a short circuit between the terminals 31, the PTC polymer 1 is provided in the peripheral portion.
An insulating container 34, which is a current limiting container for protecting the PTC element, is formed in, for example, a square shape with a container body 34a and a container lid part 34b, and the PTC element is fixed by tightening a bolt 35a and a nut 35b. Yes. In addition, a spacer 36 is provided for keeping the inner height of the insulating container 34 constant.

The elastic body 33 is, for example, a leaf spring, a disc spring, or an organic elastic body, and is disposed between the current introduction terminal 31 and the insulating container 34. In the present embodiment, the elastic body 33 is connected to the PTC element composed of the fusion electrode 2 and the PTC polymer 1, the terminal electrode 3, and the current introduction terminal 31 in a direction perpendicular to the main surface of the PTC polymer 1. Apply elastic pressure. That is, in the process in which the container lid 34b is integrated with the container body 34a, the elastic body 33 is compressed, and the pair of current introduction terminals 31 and the terminal electrodes 3a and 3b are pressed toward the PTC element and are in electrical contact with each other. ing. That is, the elastic body 33 corresponds to a pressurizing unit that presses the pair of terminal electrodes 3a and 3b toward the PTC element.
Since the terminal electrode 3 and the fused electrode 5 are in metal contact, the electrical contact resistance is low, so the pressure applied by the elastic body 33 is set low. Therefore, it is possible to prevent the PTC polymer 1 from being damaged due to high stress.

In such a configuration, the current flows through one current introduction terminal 31, one terminal electrode 3a, the PTC element, the other terminal electrode 3b, and the other current introduction terminal 31.
When a load current flows, the energization heat generation is small, so the temperature rise of the PTC polymer 1 is low, and the electrical resistance of the PTC polymer 1 is low.

  When a short circuit accident occurs and a large current flows, the PTC polymer 1 is heated by heat generated by the electrical contact resistance at the interface between the fusion electrode 2 and the PTC polymer 1. When the temperature of the PTC polymer part 1 exceeds the transition temperature, the polymer existing in the vicinity of the interface between the PTC polymer 1 and the fusion electrode 2 is melted, and the distance between the particulate conductive materials is increased. It changes from a low electrical resistance state to a high electrical resistance state, and a short circuit current is suppressed. This suppressed current is interrupted by a switch (not shown).

During the current limiting, the portion of the PTC polymer 1 in the vicinity of the interface with the fusion electrode 2 reaches the decomposition temperature far exceeding the transition temperature, and an arc is generated. The heat of the arc softens the PTC polymer 1 in the vicinity of the interface with the fusion electrode 2, and the fusion electrode 2 bites into the PTC polymer 1. As a result, the portion of the through hole 20 of the fusion electrode 2 is filled with the PTC polymer 1. In the present embodiment, since the surface of the terminal electrode 3 adjacent to the fusion electrode 2 is roughened, the PTC polymer 1 filled in the through-hole 20 of the fusion electrode 2 as the PTC polymer 1 is softened. Bite into the irregularities of the roughened surface (rough surface) of the terminal electrode 3, whereby the terminal electrode 3 and the PTC polymer 1 are heat-sealed. Thus, in this Embodiment, the terminal electrode 3 and the PTC polymer 1 are heat-seal | fused by the PTC polymer 1 biting into the unevenness | corrugation of the roughened surface (rough surface) of the terminal electrode 3. Therefore, the electrical contact resistance between the PTC polymer 1 and the terminal electrode 3 is significantly reduced. Therefore, even if the surface of the PTC polymer 1 is roughened by the heat of the arc and the electrical contact resistance between the PTC polymer 1 and the fusion electrode 2 is increased, the electrical contact between the terminal electrode 3 and the PTC polymer element is increased. Thus, the increase in resistance can be remarkably suppressed, and the decrease in energization performance before and after the current limiting operation can be remarkably suppressed.
In FIG. 1 showing the current limiting device in the initial state, the fusion electrode 2 does not bite into the PTC polymer 1, but when the fusion electrode 2 and the PTC polymer 1 are fused, the fusion electrode 2 becomes PTC. In some cases, it may bite into the polymer 1.

  Even in the conventional current limiter, the PTC polymer 1 is softened by the heat of the arc during the current limiting, and the fusion electrode 2 bites into the PTC polymer 1, so that the through hole 20 portion of the fusion electrode 2 becomes PTC. It may also be filled with polymer 1. However, in the conventional current limiter, since the surface of the terminal electrode 3 adjacent to the fusion electrode 2 on the side adjacent to the fusion electrode 2 is not roughened, the terminal electrode 2 is hardly thermally fused to the PTC polymer 1, Even if they are heat-sealed, their contact resistance is larger than that of this embodiment. As a result, the increase in electrical resistance between the terminal electrode 3 and the PTC polymer 1 cannot be suppressed remarkably as in the present embodiment, and the decrease in the energization performance before and after the current limiting operation is remarkably suppressed. Can not.

Since both the terminal electrode 3 and the fused electrode 2 are made of metal and are in metal contact, the contact resistance between the terminal electrode 3 and the fused electrode 2 is extremely low. There is no idea of roughening.
During the current limiting, the PTC polymer 1 in the vicinity of the interface with the fusion electrode 2 is softened by the heat of the arc generated in the vicinity of the interface with the fusion electrode 2 in the PTC polymer 1. The phenomenon that the through hole 20 portion of the fusion electrode 2 is filled with the PTC polymer 1 as a result of the 2 biting into the PTC polymer 1 has been clarified for the first time by the inventors of the present invention. At the time of the invention of the vessel, it was not yet clear. Therefore, when the surface of the terminal electrode 3 adjacent to the fusion electrode 2 on the side adjacent to the fusion electrode 2 is roughened, the through hole 20 of the fusion electrode 2 is filled with the softening of the PTC polymer 1. Since the terminal electrode 3 and the PTC polymer 1 are strongly heat-sealed when the PTC polymer 1 bites into the unevenness of the roughened surface (rough surface) of the terminal electrode 3, the PTC polymer 1 and the terminal electrode 3 The fact that the contact resistance is remarkably lowered was not yet clear at the time of the invention of the conventional current limiter, and the idea could not be obtained.

  The shape of the cross section perpendicular to the depth direction of the through hole 20 may be circular, square, or asymmetric keyhole. When the fusion electrode 2 and the PTC polymer 1 are fused to a part of the through hole 20, the softened PTC polymer 1 may be protruded.

In FIG. 1, the container lid 34b is integrated with the container main body 34a by tightening the bolt 35a and the nut 35b, but may be integrated with the container main body 34a with an adhesive. The insulating container 34 may be integrated in advance. In this case, the elastic body 33 is compressed in advance with a jig, and the PTC element, the terminal electrode 3 and the current introduction terminal 31 are collectively collected. 34.
In order to prevent intrusion of dust, the insulating container 34 may be formed in a sealed shape as a box shape.

Embodiment 2. FIG.
FIG. 4 is a view for explaining a current limiter according to Embodiment 2 of the present invention, and more specifically, a cross-sectional explanatory view showing a configuration of a main part of the current limiter in an initial state.
In the current limiting device according to the present embodiment, the terminal electrode 3 (both in the present embodiment, both adjacent to the fused electrode 2 (both fused electrodes 2a and 2b in the present embodiment) whose electrode area ratio is smaller than 1 is used. The terminal electrodes 3a and 3b) are represented by metal foils 301a and 301b (hereinafter, 301) which are adjacent to the fusion electrodes 2a and 2b and whose surfaces adjacent to the fusion electrodes 2a and 2b are roughened. ) And conductive plates 302a and 302b (hereinafter also represented by 302) disposed on the opposite side of the metal foils 301a and 301b on the side adjacent to the fusion electrode. Since the other configuration is the same as that of the first embodiment, the following mainly describes differences from the first embodiment.

The metal foil 301 is made of, for example, silver or nickel, and has a thickness of about 30 to 100 μm, for example. Further, the surface of the metal foil 301 on the side adjacent to the fusion electrode is roughened, that is, roughened by plating or blasting so as to have irregularities with an average roughness of, for example, 5 to 20 μm. .
The conductive plate 302 is, for example, a copper plate plated with silver or nickel, and has a thickness of about 5 to 10 μm, for example. The fused electrode 2, the metal foil 301, the conductive plate 302 and the current introduction terminal 31 are electrically connected to each other. The conductive plate 302 may be integrated with the current introduction terminal 31.

In such a configuration, when a short circuit accident occurs and a large current flows, due to an increase in electrical contact resistance at the interface between the fusion electrode 2 and the PTC polymer 1, as in the case of the first embodiment. PTC polymer 1 is heated by heat generation, PTC polymer 1 changes from a low electrical resistance state to a high electrical resistance state, and a short circuit current is suppressed.
Further, the PTC polymer 1 in the vicinity of the interface with the fusion electrode 2 is softened by the heat of the arc generated between the fusion electrode and the metal foil during the current limiting, and the fusion electrode 2 bites into the PTC polymer 1 as a result. A portion of the through hole 20 of the fusion electrode 2 is filled with the PTC polymer 1. In the present embodiment, since the surface of the metal foil 301 adjacent to the fusion electrode 2 is roughened, the PTC polymer 1 filled in the through-hole 20 of the fusion electrode 2 as the PTC polymer 1 is softened. Bite into the irregularities on the roughened surface (rough surface) of the metal foil 301, thereby forming the metal foil 301 and the PTC polymer 1. Thus, in this Embodiment, since the metal foil 301 and the PTC polymer 1 are heat-seal | fused because the PTC polymer 1 bites into the unevenness | corrugation of the roughened surface (rough surface) of the metal foil 301. The contact resistance between the PTC polymer 1 and the metal foil 301 is significantly reduced. Moreover, since both the metal foil 301 and the conductive plate 302 are made of metal and are in metal contact, the electrical contact resistance is low.
Therefore, even if the surface of the PTC polymer 1 is roughened by the heat of the arc and the contact resistance between the PTC polymer 1 and the fusion electrode 2 is increased, the resistance increase between the metal foil 301 and the PTC polymer element is remarkable. It is restrained and the fall of the electricity supply performance before and behind current limiting operation can be suppressed notably.

  Further, in the present embodiment, since there is a thermal contact resistance between the metal foil 301 and the conductive plate 302, heat from an arc generated between the metal foil 301 and the PTC polymer 1 due to the current limiting operation. Since it becomes difficult to transmit from the metal foil 301 to the conductive plate 302, the temperature rise of the metal foil 301 increases. As a result, the metal foil 301 is very strongly heat-sealed to the PTC polymer 1, and an increase in electrical contact resistance between the metal foil 301 and the PTC polymer 1 is remarkably suppressed. Can be more remarkably suppressed.

  If the thickness of the metal foil 301 is too thin, the metal foil evaporates due to arc heat generated between the fusion electrode and the metal foil during current limiting. If the thickness is too thick, the temperature rise of the metal foil 301 is too large. Therefore, about 20 to 100 μm is desirable.

Embodiment 3 FIG.
FIG. 5 is a view for explaining a current limiting device according to Embodiment 3 of the present invention, and more specifically, a cross-sectional explanatory view showing a configuration of a main part of the current limiting device in an initial state.
In the current limiter according to the present embodiment, the pair of fusion electrodes 2a and 2b have different electrode area ratios, and the fusion electrode of the terminal electrode 3b adjacent to the fusion electrode 2b having the larger electrode area ratio. The surface on the 2b adjacent side is not roughened.

  In each of the above embodiments, the fusion electrodes 2 a and 2 b are thermally fused to both main surfaces of the PTC polymer 1. The fused surface of one fused electrode 2a will be referred to as A surface, and the fused surface of the other fused electrode 2b will be referred to as B surface. In Embodiments 1 and 2, the electrode area ratio of the A surface (ratio of the area of the fusion surface of the fusion electrode 2a with the PTC polymer 1 to the area of the fusion surface of the PTC polymer 1 with the fusion electrode 2a) And the surface area ratio of the B surface (the ratio of the area of the fused surface of the fused electrode 2b with the PTC polymer 1 to the area of the fused surface of the PTC polymer 1 with the fused electrode 2b) was the same.

  As a result of the experiment, even if the electrode area ratio on the A surface and the electrode area ratio on the B surface are the same as described above, the connection portion with the PTC polymer 1 on the A surface (hereinafter also referred to as the A surface connection portion). The electrical contact resistance of the B surface and the electrical contact resistance of the connection portion with the PTC polymer 1 on the B surface (hereinafter sometimes referred to as the B surface connection portion) are not exactly the same and are slightly different. Therefore, when a short-circuit current flows, it was found that there is a time difference in arc generation between the A side connection part and the B side connection part. And it turned out that the time of a current-limiting peak value substantially corresponds to the time of arc occurrence of the surface where the arc has occurred first in the A surface and the B surface. After the point of the current limiting peak value, an arc current having a magnitude that is a fraction of the current limiting peak value flows. From this result, it was found that even if the arc generation surface is limited to one surface, the current limiting wave height value is almost the same.

Therefore, in the present embodiment, the electrode area ratio of the B surface (fused surface of the fusion electrode 2b) is configured to be larger than the electrode area ratio of the A surface (fusion surface of the fusion electrode 2a). .
In such a configuration, when a short circuit accident occurs and a large current flows, the PTC polymer 1 is heated by heat generated by the contact resistance at the interface between the fusion electrode 2 and the PTC polymer 1, and the PTC polymer 1 The portion near the A-plane connection portion with the smaller electrode area ratio changes from the low resistance state to the high resistance state, and the short-circuit current is suppressed. In addition, since the current density is small, the temperature rise is low in the vicinity of the B-surface connection portion having the larger electrode area ratio in the PTC polymer 1.
Further, during the current limiting, the portion of the PTC polymer 1 in the vicinity of the A-plane connection portion having the smaller electrode area ratio reaches the decomposition temperature far exceeding the transition temperature, and an arc is generated. Due to the heat of the arc, the PTC polymer 1 in the vicinity of the A-plane connection portion is softened, and as in the case of each of the above embodiments, the through hole 20 of the fusion electrode 2a is filled with the softening of the PTC polymer 1. The PTC polymer 1 bites into the irregularities on the roughened surface (rough surface) of the terminal electrode 3a, whereby the terminal electrode 3a and the PTC polymer 1 are heat-sealed. The current limiting peak value is a current value at the time when the PTC polymer 1 changes from the low resistance state to the high resistance state in the vicinity of the A-surface connection portion with the smaller electrode area ratio, so the current limiting peak value is high. There is little to be.
In addition, since the current density is low, the arc does not occur in the vicinity of the B surface connection portion having the larger electrode area ratio in the PTC polymer 1. The current limiting peak value is a current value at the time when the PTC polymer 1 changes from the low resistance state to the high resistance state in the vicinity of the A-surface connection portion with the smaller electrode area ratio, so the current limiting peak value is high. There is little to be.

  Thus, according to the present embodiment, among the PTC polymers 1, it is possible to reduce the resistance of the B surface connection portion having the larger electrode area ratio, so that the initial resistance of the current limiter can be reduced. The current-crest peak value is determined by the A surface having the smaller electrode area ratio. As a result, since the initial resistance of the current limiter can be reduced without increasing the current limiting peak value, the energization performance can be improved. In addition, since the arc generation associated with the current limiting operation is limited to one surface (surface with a small electrode area ratio), the resistance of the current limiting device after the current limiting operation increases, that is, the current-carrying performance decreases before and after the current limiting operation. Can be remarkably suppressed. As a result, a current limiter having high energization performance in the initial state and high energization performance after the current limiting operation can be obtained.

  In the present embodiment, the pair of fusion electrodes 2 have different electrode area ratios, so that arc generation associated with the current limiting operation is limited to one surface of the PTC polymer 1 (surface having a small electrode area ratio). The terminal electrode 3a adjacent to the fusion electrode 2a having the smaller electrode area ratio and the PTC polymer 1 are thermally fused. Therefore, the surface of the terminal electrode 3b adjacent to the fusion electrode 2b, which is adjacent to the fusion electrode 2b having the larger electrode area ratio and is not thermally fused to the PTC polymer 1, may not be roughened. The manufacturing process can be simplified.

  Further, the surface of the terminal electrode 3 (for example, 3a) adjacent to the fusion electrode 2a (for example, 3a) adjacent to the fusion electrode 2a having an electrode area ratio smaller than 1 is roughened. The surface of the terminal electrode 3 (for example, 3b) adjacent to the fused electrode 2b (for example, 3b) adjacent to the fused electrode 2b may not be roughened.

  Further, at least the terminal electrode 3 (for example, 3a) adjacent to the fusion electrode 2 (for example, 2a) having the smaller electrode area ratio is adjacent to the fusion electrode 2 and the surface adjacent to the fusion electrode 2 is roughened. The metal foil 301 (for example, 301a) and the conductive plate 302 (for example, 302a) disposed on the opposite side of the metal foil 301 (for example, 301a) on the side adjacent to the fusion electrode 2 (for example, 2a) may be used. Well, the same effect as in the third embodiment can be obtained.

  When the electrode area ratio of the pair of fusion electrodes 2a and 2b is different from each other as in the present embodiment, the electrode area ratio of the fusion electrode 2b having the larger electrode area ratio exceeds 90%. When the polymer 1 and the fusion electrodes 2a and 2b are thermally fused, the PTC polymer 1 is greatly warped due to the difference in the degree of thermal shrinkage between the fusion electrode 2b and the fusion electrode 2a. When this is pressurized with the elastic body 33, the internal stress of the PTC polymer 1 increases, and the PTC polymer 1 is easily damaged during the current limiting operation.

  Therefore, by setting the electrode area ratio of the fusion electrode 2b having the larger electrode area ratio to 90% or less, the initial stress acting on the PTC polymer 1 can be suppressed, so that the damage of the PTC polymer 1 during the current limiting operation can be prevented. Can be suppressed. As a result, a current limiter with a large number of current limiting operations can be obtained.

  The electric resistance of the current limiting device is greatly reduced as the electrode area ratio is increased. However, when the electrode area ratio is 50% or more, the degree of decrease is reduced. Therefore, in consideration of the above, when the electrode area ratios of the fusion electrodes 2a and 2b are different from each other, if the electrode area ratio of the fusion electrode 2b having the larger electrode area ratio is set to 50% or more and 90% or less, PTC The warping of the polymer 1 can be suppressed, and the electric resistance of the current limiting device can be set low.

Embodiment 4 FIG.
FIG. 6 is a view for explaining a current limiting device according to Embodiment 4 of the present invention, and more specifically, a perspective view showing a configuration of a PTC element.
The present embodiment is the same as the above embodiments except that the fusion electrode 2 is divided into a plurality of portions and the minute fusion electrode portions 21 are uniformly distributed in an island shape. In the following, differences from the above embodiments will be mainly described.

  In each of the above-described embodiments, since the through-hole 20 is formed in the fusion electrode 2, the fusion of the PTC polymer 1 with the PTC polymer 1 with respect to the area of the fusion surface of the PTC polymer 1 with the fusion electrode 2. The electrode area ratio, which is the ratio of the area of the contact surface, was smaller than 1. As described above, when the through-hole 20 is formed in the fusion electrode 2, if the electrode area ratio is to be reduced, the distance between the adjacent through-holes 20, that is, the width of the non-hole portion of the fusion electrode 2 is reduced. It becomes necessary to do. However, there is a limit in reducing the width of the non-hole portion of the fused electrode 2 in processing. Therefore, there is a limit in reducing the electrode area ratio. Further, when the width of the non-hole portion of the fusion electrode 2 is reduced to the limit, the generation of the arc is localized in the non-hole portion where the width of the fusion electrode 2 is narrow. Thermal stress increases, and the PTC polymer 1 is easily damaged.

Therefore, in the present embodiment, as shown in FIG. 6, the fusion electrode 2 is divided into a plurality of pieces, and the minute fusion electrode portions 21 are uniformly distributed in an island shape.
With such a configuration, even when the electrode area ratio is reduced, the arc can be generated uniformly and distributed, so that the thermal stress generated in the PTC polymer 1 is dispersed, and the local thermal stress is reduced. It can be made difficult to cause damage.
Moreover, since the current flowing through the PTC polymer 1 can be uniformly dispersed when the load current is applied, the energization performance can be improved.

However, it is extremely difficult to thermally disperse each of the minute fused electrode portions 21 divided into a plurality of pieces as described above into the PTC polymer 1 and to disperse and arrange them in an island shape uniformly.
Therefore, in the present embodiment, the manufacturing is performed as follows.
First, the large fusion electrode 2 before being divided into a plurality of parts is thermally fused to the PTC polymer 1 entirely. Next, the non-electrode portion is removed by an etching method.
According to such a processing method, for example, when the fused electrode portion 21 has a prismatic shape as shown in FIG. 6, it can be easily formed as small as about 0.2 mm on a side, and the fusion electrode portion 21 is dispersed. Can increase the sex.

  The shape of the fused electrode portion 21 is not limited to a prismatic shape, and may be another shape such as a cylindrical shape.

Embodiment 5 FIG.
FIG. 7 is a view for explaining a current limiting interrupting device according to Embodiment 5 of the present invention, and more specifically, a cross-sectional view showing a configuration of the current limiting interrupting device.
The current limiting interrupter according to the present embodiment is mainly composed of a current limiter 100 and a switch 200 having a pair of fused electrodes having different electrode area ratios as described in the third embodiment. The switch 200 has an opening / closing part 201 that opens and closes an electric circuit. Basically, the opening / closing part 201 includes a fixed contact 201a and a movable contact 201b. Regarding the opening and closing of the electric circuit, the opening / closing operation of the movable contact 201b is performed manually or automatically by detecting an excessive current by a mechanism (not shown), but may be performed by a self-extinguishing semiconductor device.

  In the present embodiment, the current limiter 100 is disposed close to the switch 200. The current introduction terminal 31a connected to the terminal electrode adjacent to the fusion electrode having the larger electrode area ratio in the current limiter 100 is connected to one terminal 202a of the switch 200, and the fusion electrode having the smaller electrode area ratio is connected. The current introduction terminal 31b connected to the terminal electrode adjacent to the arrival electrode is connected to the external electric wire. The other terminal 202b of the switch is connected to an external electric wire.

  In such a configuration, when a load current flows, the switch 200 generates heat in the switch 200. This generated heat is dissipated to the external wire mainly through the terminal 202b connected to the external wire of the switch 200. Further, in the current limiting device 100, heat is generated in the vicinity of the fusion electrode having a small electrode area ratio and in the vicinity of the fusion electrode having a large electrode area ratio, but the amount of generated heat is greater in the vicinity of the fusion electrode having a small electrode area ratio. Moreover, since the main component of the PTC polymer which is the main part of the current limiting device 100 is a polymer as described above, the thermal conductivity is very small. In the present embodiment, the current introduction terminal 31b connected to the terminal electrode adjacent to the vicinity of the fusion electrode having the larger calorific value and the smaller electrode area ratio is not the switch 200 side, and the heat radiation is efficiently performed. This heat generation is efficiently radiated to the external electric wire side. Therefore, high current-carrying performance of the current limiter 100 can be obtained.

Embodiment 6 FIG.
FIG. 8 is a view for explaining a current limiting interrupting device according to Embodiment 6 of the present invention, and more specifically, a cross-sectional view showing a configuration of the current limiting interrupting device.
In the present embodiment, the current limiter 100 is housed inside the container of the switch 200. Thus, by incorporating the current limiter 100 in the switch 200, the storage container can be shared and a useless space can be removed. Therefore, the size can be reduced as compared with that of FIG. it can.

In the present embodiment, current limiting device 100 may have any of the configurations described in the first to fourth embodiments.
However, as in the fifth embodiment, when the current limiter 100 having a pair of fused electrodes having different electrode area ratios is used, the electrode area ratio of the current limiter 100 having the larger electrode area ratio is larger. The current introduction terminal 31a connected to the terminal electrode adjacent to the fusion electrode is connected to one terminal 202a of the switch 200, and the current connected to the terminal electrode adjacent to the fusion electrode having a smaller electrode area ratio. By connecting the introduction terminal 31b to an external electric wire, it is possible to obtain a current-limiting circuit breaker that is small and has high energization performance.

It is sectional explanatory drawing which shows the whole structure in the initial state of the fault current limiter by Embodiment 1 of this invention. It is a top view which shows the structure of the PTC element which is the principal part of the fault current limiter by Embodiment 1 of this invention. It is sectional explanatory drawing which shows the structure of the principal part after the current limiting operation | movement of the current limiting device by Embodiment 1 of this invention. It is sectional explanatory drawing which shows the structure of the principal part in the initial state of the fault current limiter by Embodiment 2 of this invention. It is sectional explanatory drawing which shows the structure of the principal part in the initial state of the fault current limiter by Embodiment 3 of this invention. It is a perspective view which shows the structure of the PTC element which is the principal part of the fault current limiter by Embodiment 4 of this invention. It is sectional explanatory drawing which shows the structure of the current limiting interrupting device by Embodiment 5 of this invention. It is sectional explanatory drawing which shows the structure of the current limiting interruption device by Embodiment 6 of this invention.

Explanation of symbols

  1 PTC polymer, 2, 2a, 2b fused electrode, 20 through hole, 21 fused electrode part, 3, 3a, 3b terminal electrode, 301, 301a, 301b metal foil, 302, 302a, 302b conductive plate, 31, 31a , 31b Current introduction terminal, 32 Insulating frame, 33 Elastic body, 34 Insulating container, 35a Bolt, 35b Nut, 36 Spacer, 100 Current limiter, 200 Switch, 201 Opening / closing part, 201a Fixed contact, 201b Movable contact, 202a, 202b terminal.

Claims (9)

A PTC element comprising a PTC polymer and a pair of fusion electrodes that are arranged opposite to each other with the PTC polymer sandwiched therebetween and fused to the PTC polymer, and is arranged on the opposite side to the PTC polymer arrangement side of the pair of fusion electrodes. A pair of terminal electrodes adjacent to the pair of fusion electrodes, and a pressing means for pressing the pair of terminal electrodes to the PTC element side, and at least one fusion electrode of the pair of fusion electrodes Has a through-hole formed or is divided into a plurality of islands and arranged in an island shape so that the area of the fusion surface of the PTC polymer with the fusion electrode of the fusion electrode and the PTC polymer of the fusion electrode The surface of the terminal electrode adjacent to the fused electrode having a ratio of the electrode area, which is a ratio of the area of the fused surface, smaller than 1 and the electrode area ratio being smaller than 1 is a rough surface. Current limiter, characterized in that it is. The current limiting device according to claim 1, wherein the fused surface of the fused electrode having an electrode area ratio smaller than 1 is roughened. The terminal electrode adjacent to the fusion electrode having an electrode area ratio smaller than 1 is a metal foil having a roughened surface adjacent to the fusion electrode and adjacent to the fusion electrode, and adjacent to the fusion electrode of the metal foil. The current limiting device according to claim 1, wherein the current limiting device comprises a conductive plate disposed on the opposite side to the side. The current limiting device according to claim 1 or 2, wherein the pair of fused electrodes have different electrode area ratios. 5. The current limiting device according to claim 4, wherein a surface of the terminal electrode adjacent to the fusion electrode having a larger electrode area ratio is not roughened. The terminal electrode adjacent to the fusion electrode having the smaller electrode area ratio is a metal foil having a roughened surface adjacent to the fusion electrode and adjacent to the fusion electrode, and the fusion electrode adjacent side of the metal foil. The current limiting device according to claim 4, wherein the current limiting device includes a conductive plate disposed on the opposite side of the current limiting plate. The current limiting device according to claim 4, wherein the electrode area ratio of the fused electrode having the larger electrode area ratio is 50% or more and 90% or less. A current limiting device comprising a series of a current limiting device having a pair of fused electrodes with different electrode area ratios according to any one of claims 4 to 6 and a switch for opening and closing an electric circuit, A current limiting interrupter, wherein a terminal electrode adjacent to a fused electrode having a larger electrode area ratio in the current limiting device is connected to the switch. The current limiting device according to any one of claims 1 to 6 and a switch for opening and closing an electric circuit are connected in series, and the current limiting device is built in the switch. Current-limiting circuit breaker characterized by

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