JPS6179203A - Current limiting resistance element - Google Patents

Abstract

(57)【要約】本公報は電子出願前の出願データであるた
め要約のデータは記録されません。(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

【発明の詳細な説明】 ［発明の技術分野］ 本発明は、電流の導通時に自己発熱して抵抗が増加しも
って過電流の導通を防止する限流、抵抗素子に関する。DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a current-limiting and resistive element that generates self-heating when current is conducted, increases resistance, and thereby prevents conduction of overcurrent.

［発明の技術的背景とその問題点］ 比抵抗の温度係数が正である、すなわち、温度上昇に伴
って比抵抗が増加する物質いわゆるＰＴ（ｉ特性を有す
る物質を例えば円柱形状に加工してこれを素子本体とし
、該素子本体の両端に電流端子としての電極を添着した
構造の限流抵抗素子が開発されている。[Technical background of the invention and its problems] Materials with a positive temperature coefficient of resistivity, that is, whose resistivity increases as the temperature rises, so-called PT A current-limiting resistor element has been developed which has a structure in which this is used as an element body and electrodes as current terminals are attached to both ends of the element body.

この素子は電力回路に挿入されて使用される。This element is used by being inserted into a power circuit.

回路に過電流が流れた場合には、該素子本体が自己発熱
して温度上昇し、その結果、素子本体の比抵抗が増加し
て導通する電流値を制限する。When an overcurrent flows through the circuit, the element body self-heats and its temperature rises, and as a result, the specific resistance of the element body increases and limits the current value that conducts.

このようなことから、各種機器の小型化、小容量化を企
るためにその目的に適合する限流抵抗素子の研究が進め
られている。For this reason, in order to reduce the size and capacity of various devices, research is underway into current-limiting resistive elements that are suitable for these purposes.

しかしながら、ＰＴＣ！特性を有する物質の例えば円柱
体に通電した場合、例えば電流の導通方向でその温度分
布が不均一になることがある。However, PTC! When electricity is applied to, for example, a cylindrical body of a material having characteristics, the temperature distribution may become non-uniform in the direction of current conduction.

例えば電極に用いる材料あるいは電極接合に用いる材料
、また電極の形成方法によっては電極および電極接合部
に抵抗体本体の比抵抗よりも大きな比抵抗を有する高抵
抗層が形成され、同部分における単位断面積あたりの通
電容量が抵抗体自体における単位断面積あたりの通電容
量に比較して小さいものとなる場合がある。For example, depending on the material used for the electrode or the material used for electrode bonding, or the method of forming the electrode, a high-resistance layer having a resistivity larger than that of the resistor body may be formed at the electrode and electrode bonding portion, and a unit cross section in the same portion may form. The current carrying capacity per area may be smaller than the current carrying capacity per unit cross-sectional area of the resistor itself.

本発明に係る限流抵抗素子のような大電流用途に用いら
れる素子の場合、特に□その材料がＶｌＩ０９のような
酸化物である場合には、その電極接合には、Ｔｉ等の活
性金属を含むロウ材を用いて、Ｃｕ板等を真空ロウ材に
よって接合することがおこなわれている。このような活
性金属ロウ材は非常に酸化がおこりやすく通常の生産設
備で用いられる真空接合炉等によるロウ材の雰囲気にお
いては、接合面に酸化被験が形成される場合があり、ま
た高文空中において接合しても■２０８の如き酸化物と
の接触面では、ロウ材の酸化がおこり同様の酸化被膜が
形成される場合がある。In the case of an element used for large current applications such as the current limiting resistor element according to the present invention, especially when the material is an oxide such as VlI09, an active metal such as Ti is used for the electrode bonding. A vacuum brazing material is used to join Cu plates and the like using a vacuum brazing material. Such active metal brazing materials are extremely susceptible to oxidation, and in the atmosphere of the soldering materials in vacuum bonding furnaces used in normal production equipment, oxidation marks may be formed on the joint surfaces. Even when bonded at 208, the brazing material may be oxidized and a similar oxide film may be formed on the contact surface with the oxide such as 208.

かかる酸化被膜は通常Ｖ２Ｏ３＠限流抵抗素子本体を形
成する材料よりその比抵抗が大きく、相互的に高抵抗層
を形成し、電極接合面の単位断面積あたりの通電容量を
低下させるものである。Such an oxide film usually has a higher specific resistance than the material forming the main body of the V2O3@current limiting resistor element, mutually forming a high resistance layer, and reducing the current carrying capacity per unit cross-sectional area of the electrode bonding surface. .

このような場合には抵抗体が自己発熱による昇温を発生
する通電電流以下の電流値において電極および電極接合
面付近の自己発熱による昇温か生じ限流抵抗素子として
の通電容量が低下するという問題があった。In such a case, at a current value that is less than the current value at which the resistor generates temperature rise due to self-heating, the current-carrying capacity as a current-limiting resistor element decreases due to self-heating in the vicinity of the electrodes and the electrode bonding surface. was there.

また過大電流通電時の自己発熱による抵抗増加動作時に
おいても電極あるいは電極接合面付近の温度が抵抗体中
央部より高温になるような不均一昇温か生じ、限流抵抗
素子を楡成する材料の比抵抗の温度依存性の特性によっ
ては、この温度分布の不均一によって抵抗体全体の抵抗
値が有効に増加せず限流抵抗素子として有効に機能しな
い場合があった。Furthermore, when the resistance increases due to self-heating when excessive current is applied, a non-uniform rise occurs in which the temperature near the electrode or the electrode bonding surface becomes higher than the center of the resistor, and the material forming the current-limiting resistor element. Depending on the characteristics of the temperature dependence of specific resistance, the resistance value of the entire resistor may not effectively increase due to the non-uniform temperature distribution, and the resistor may not function effectively as a current limiting resistor element.

［発明の目的］ 本発明はかかる事情に鑑みなされたものであって限流抵
抗素子における電極および電極接合面付近の自己発熱を
防止し限流抵抗素子の定格通電容量を増加させ、また過
電流通電時の温度上昇の不均一を防止し限流抵抗素子の
抵抗値を有効に増加させることを目的とする。[Objective of the Invention] The present invention has been made in view of the above circumstances, and is capable of preventing self-heating near the electrodes and electrode bonding surfaces in a current limiting resistance element, increasing the rated current carrying capacity of the current limiting resistance element, and preventing overcurrent. The purpose of this invention is to effectively increase the resistance value of a current limiting resistor element by preventing uneven temperature rise during energization.

［発明の概要］ 本発明においては上記目的を達成するためにＰＴＣ抵抗
特性を有する抵抗体に電極を付与してなる限流抵抗素子
において電極および電極接合部の電流方向に垂直なる断
面積を抵抗体中央部の断面積より増大せしめかかる部位
における通電時の電流密度を低下させることによって同
部位の温度上昇を制限して電極材料、電極接合材料ある
いは電極接合方法に起因する定格通電容量の低下を防止
するものであり、また電極あるいは電極接合部の低通電
容量に起内する、過大電流通電時・の不均一昇温を防止
するものである。本発明は各種のＰＴＣ抵抗材料を用い
る限流抵抗素子に有効であるが室温でのρが１０１〜１
０２０−と大きいＢａＴ　ｉＯＢ系に比べ、　Ｃｒ、Ａ
ｌを添加したｖ８０Ｂの如くその常温における比抵抗が
１０−４〜１０−８ｎ国と小さく大きな電流零Ｉ゛をも
つＰＴＣ抵抗材料を用いた限流抵抗素子においては特に
有効であり、同時に同材料の如くある温度でＰＴＣ特性
からＮＴＣ特性に変化する比抵抗の温度依存性を有する
材料を用いた限流抵抗素子において特に有効である。ま
たＣｒ、Ａｌを添加したｖ２ｏＢ多結晶焼結体からなる
セラミック限流抵抗素子、さらにＣｒ、Ａｌを添加した
■２０８にＦｅ、　Ｃｕ、　Ｎｌ。[Summary of the Invention] In order to achieve the above object, the present invention provides a current limiting resistance element in which an electrode is attached to a resistor having PTC resistance characteristics, and the cross-sectional area perpendicular to the current direction of the electrode and the electrode junction is defined as a resistance. By lowering the current density during current flow in a region whose cross-sectional area is larger than that of the central part of the body, the temperature rise in that region is limited and the rated current-carrying capacity is reduced due to the electrode material, electrode bonding material, or electrode bonding method. It also prevents uneven temperature rise when excessive current is applied due to the low current carrying capacity of the electrodes or electrode junctions. The present invention is effective for current limiting resistance elements using various PTC resistance materials, but the ρ at room temperature is 101 to 1.
020- compared to the large BaT iOB system, Cr, A
It is particularly effective in current limiting resistor elements using PTC resistance materials, such as V80B, which has a small resistivity at room temperature of 10-4 to 10-8 n and a large current of zero, such as V80B, which is doped with l. This is particularly effective in a current limiting resistance element using a material having a temperature dependence of resistivity that changes from PTC characteristics to NTC characteristics at a certain temperature, such as. In addition, there is a ceramic current limiting resistor element made of a v2oB polycrystalline sintered body to which Cr and Al are added, and 208 (208) to which Cr and Al are added, as well as Fe, Cu, and Nl.

Ｃｏ、　８ｎのうち少くとも１種を添加して焼結性を向
上させた多結晶焼結体からなるセラミック限流抵抗素子
においても同様に有効である。この際添加するＣｒの一
部あるいは全部なＡｌで置換しても同様の特性が得られ
るが、添加するＣｒあるいはＡｊの添加量は１．５モル
チ以下（０≦ｘ≦０．０１５）である必要があり、これ
以上の添加においてはＰＴＣ特性が得にくい。またＦｅ
、　Ｃｕ、　Ｎｌ、　Ｃｏ、　Ｓｎのうち少くとも１種
を添加して焼結性を向上させる場合には２０ｗｔ　％以
下であることが必要でありこれ以上の添加においては温
度変化に伴う比抵抗変化率が減少し有効な限流抵抗材料
とはなり難い。The present invention is also effective in a ceramic current limiting resistance element made of a polycrystalline sintered body to which at least one of Co and 8n is added to improve sinterability. At this time, the same characteristics can be obtained even if part or all of the added Cr is replaced with Al, but the amount of added Cr or Aj is 1.5 molti or less (0≦x≦0.015). If more than this is added, it is difficult to obtain PTC characteristics. Also Fe
When adding at least one of Cu, Nl, Co, and Sn to improve sinterability, it is necessary to add 20 wt % or less, and adding more than this will cause specific resistance changes due to temperature changes. The resistance decreases, making it difficult to be an effective current limiting resistance material.

素子形状は前述のごとく、雷、極近傍で断面積が太きけ
れば良く、円柱形に限定されるものではない。又、断面
積の違いの程度は電極材料等によっても異なるため、−
概には決められないが、断面積比で２：１から９：１種
度が望ましい。As mentioned above, the element shape is not limited to a cylindrical shape, as long as it has a large cross-sectional area in the very vicinity. Also, the degree of difference in cross-sectional area varies depending on the electrode material, etc., so -
Although it cannot be determined generally, a cross-sectional area ratio of 2:1 to 9:1 is desirable.

又、このような形状は、電極と素子本体の抵抗体との接
合面に高抵抗層が形成された場合にのみ有効であり、前
記活性金属を含むロウ材において電極接合をおこなった
限流抵抗素子において特に有効である。Moreover, such a shape is effective only when a high resistance layer is formed on the joint surface between the electrode and the resistor of the element body, and the current limiting resistor is formed by bonding the electrode with the brazing material containing the active metal. It is particularly effective in devices.

［発明の効果］ 以上のように本発明の限流抵抗素子は過電流の通電時に
自己発熱のアンバランスによる温度分布の不均一が抑制
され、もって素子全体の抵抗が増加して電流制限を有効
に達成することができ七の工業的価値は犬である。[Effects of the Invention] As described above, the current limiting resistor element of the present invention suppresses uneven temperature distribution due to unbalanced self-heating when overcurrent is applied, thereby increasing the resistance of the entire element and effectively limiting current. Seven industrial values that can be achieved are dogs.

［発明の実施例］ 以下実施例に基き本発明の詳細な説明する。[Embodiments of the invention] The present invention will be described in detail below based on Examples.

（Ｖｏ、ｏｏａｏ　Ｃｒｏ、ｏｏ４ｏ　）２０８にＳｎ
を３ｗｔｑ６添加した多結晶焼結体を作製し電極として
Ｃｕ板を活性金属を含有したロウ材によって接合したセ
ラミック限流抵抗素子を用意した。かかる限流抵抗素子
を炉中に設置し加熱して測定した静的な抵抗一温度特性
を第１図に示す。試料形状は第２図に示す如く円形の断
面を有し電極及び電極接合部において断面積が増大し電
流密度を低下させている。また比較例として同一の材料
を用いて作製した第３図に示す断面積均一の試料を用意
した。(Vo, ooao Cro, oo4o) Sn to 208
A ceramic current-limiting resistance element was prepared by preparing a polycrystalline sintered body to which 3wtq6 of was added and bonding a Cu plate as an electrode with a brazing material containing an active metal. FIG. 1 shows the static resistance-temperature characteristics measured by placing such a current limiting resistor element in a furnace and heating it. The sample shape has a circular cross section as shown in FIG. 2, and the cross-sectional area increases at the electrode and electrode junction, reducing the current density. Further, as a comparative example, a sample having a uniform cross-sectional area as shown in FIG. 3 and made using the same material was prepared.

これらの試料を第４図に示す回路中に挿入し４０Ａおよ
び１００　Ａの電流を通電したときの回路電流の時間変
化を第５〜８図に示す。When these samples were inserted into the circuit shown in FIG. 4 and currents of 40 A and 100 A were applied, the time changes in the circuit current are shown in FIGS. 5 to 8.

第５図にみられるように実施例においてＦｉ、４０Ａの
通電電流においては素子抵抗が増大せず回路電流は減少
することなく安定した通電容量が保持されている。一方
第７図にみられるように比較例では電極接合部分の発熱
、昇温により素子抵抗が増加して回路電流が減少してい
る。このように本発明になる電極および電極接合部分の
断面積増加は限流抵抗素子の定格通電容量増加をもたら
すことがわかる。As seen in FIG. 5, in the example, when Fi is applied at a current of 40 A, the element resistance does not increase, the circuit current does not decrease, and a stable current carrying capacity is maintained. On the other hand, as shown in FIG. 7, in the comparative example, the element resistance increases due to heat generation and temperature rise at the electrode joint portion, and the circuit current decreases. As described above, it can be seen that the increase in the cross-sectional area of the electrode and the electrode joint portion according to the present invention results in an increase in the rated current carrying capacity of the current limiting resistance element.

また第６図、第８図は定格電流以上の電流値１００Ａを
通電した場合を示す０第６図に示す実施例においては限
流抵抗素子の中央部分が均一に昇温し素子抵抗が増加し
て回路電流を有効に減少させる。一方第８図に示す比較
例においては電極接合部が素子中央部より発熱量が大き
く素子温度の不均一により素子抵抗値の増加は小さく回
路電流の減少も大幅に低下していることがわかる。In addition, Figures 6 and 8 show the case where a current value of 100 A, which is higher than the rated current, is applied. In the example shown in Figure 6, the temperature rises uniformly in the central part of the current limiting resistor element, and the element resistance increases. effectively reducing the circuit current. On the other hand, in the comparative example shown in FIG. 8, the amount of heat generated at the electrode junction is larger than that at the center of the element, and due to the non-uniformity of the element temperature, the increase in element resistance is small and the decrease in circuit current is also significantly reduced.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は限流抵抗素子の抵抗値の温度特性図、第２図は
本実施例の断面図、第３図は比較例の断面図、第４図は
測定用回路図、第５図及び第６図は実施例の電極一時間
曲線図、第７図及び第８図は比較例の電流一時間曲線図
０ １・・・ＰＴＣ抵抗体　　　２・・・電極３・・・限流
抵抗素子　　４・・・交流電源５・・・固定抵抗　　　
　６・・・電流測定装置代理人　弁理士　則　近　憲　
佑（ほか１名）（ｔｊ）１番Fig. 1 is a temperature characteristic diagram of the resistance value of the current limiting resistance element, Fig. 2 is a cross-sectional view of this example, Fig. 3 is a cross-sectional view of a comparative example, Fig. 4 is a measurement circuit diagram, and Figs. Figure 6 is an electrode one-hour curve diagram of the example, and Figures 7 and 8 are current one-hour curve diagrams of comparative examples. 4...AC power supply 5...Fixed resistance
6...Current measuring device agent Patent attorney Nori Chika
Yu (1 other person) (tj) No. 1

Claims (1)

【特許請求の範囲】 １、比抵抗の温度係数が正である物質の素子本体と、該
素子本体の両端に添着される一対の電極とからなる限流
抵抗素子であつて、 該素子本体の電流方向に垂直なる断面積が、電流の導通
方向において、該素子本体の中央部に比較して該電極の
近傍部の方が大であることを特徴とする限流抵抗素子。 ２、該素子本体が、次式：（Ｖ＿１＿−＿ｘＡ＿ｘ）＿
２Ｏ＿３（式中、ｘは０≦ｘ≦０．０１５を満足する数
を表わす。ＡはＣｒ、Ａｌの少なくとも一種）で示され
る物質から成る特許請求の範囲第１項に記載の限流抵抗
素子。 ３、該素子本体が、次式：（Ｖ＿１＿−＿ｘＡ＿ｘ）＿
２Ｏ＿３（式中、ｘは０≦ｘ≦０．０１５を満足する数
を表わす。ＡはＣｒ、Ａｌの少なくとも一種）で示され
る多結晶焼結体から成る特許請求の範囲第１項に記載の
限流抵抗素子。 ４、該多結晶焼結体が、更に、鉄、鋼、ニッケル、コバ
ルト、錫の群から選ばれる少なくとも１種の元素を０．
０１〜２０重量％含有している多結晶焼結体である特許
請求の範囲第３項記載の限流抵抗素子。[Claims] 1. A current limiting resistance element comprising an element body made of a material with a positive temperature coefficient of resistivity, and a pair of electrodes attached to both ends of the element body, comprising: 1. A current-limiting resistance element, wherein a cross-sectional area perpendicular to the current direction is larger in the vicinity of the electrode than in the central part of the element main body. 2. The element body has the following formula: (V_1_−_xA_x)_
2O_3 (where x represents a number satisfying 0≦x≦0.015; A is at least one of Cr and Al); . 3. The element body has the following formula: (V_1_−_xA_x)_
2O_3 (where x represents a number satisfying 0≦x≦0.015; A is at least one of Cr and Al) according to claim 1, consisting of a polycrystalline sintered body represented by Current limiting resistance element. 4. The polycrystalline sintered body further contains at least one element selected from the group of iron, steel, nickel, cobalt, and tin.
The current limiting resistance element according to claim 3, which is a polycrystalline sintered body containing 01 to 20% by weight.