JP4277454B2

JP4277454B2 - Thermal overload relay

Info

Publication number: JP4277454B2
Application number: JP2001048626A
Authority: JP
Inventors: 健司鈴木
Original assignee: Fuji Electric FA Components and Systems Co Ltd
Current assignee: Fuji Electric FA Components and Systems Co Ltd
Priority date: 2001-02-23
Filing date: 2001-02-23
Publication date: 2009-06-10
Anticipated expiration: 2021-02-23
Also published as: JP2002251948A

Description

【０００１】
【発明の属する技術分野】
本発明は、電磁接触器などに組合せて使用する熱動形過負荷継電器（サーマルリレー）に関する。
【０００２】
【従来の技術】
頭記の熱動形過負荷継電器は、通電電流の加熱により湾曲変位する主バイメタル、主バイメタルと連動するシフタの変位に従動する釈放レバー、釈放レバーで駆動される接点開閉用の反転機構、および接点機構からなり、主バイメタルの湾曲変位量が規定値を超えた際に反転機構が反転動作して接点を開閉させるようにしたものである。
【０００３】
ここで、前記の反転機構は、脚部の先端を支点として軸受部材に揺動可能に支承された略Ｕ字形の可動板と、前記支点を挟んで可動板とその下方に配した支持アームとの間に張架した反転ばね（線条の引っ張りコイルばね）とからなる。また、かかる反転機構を主バイメタルの湾曲変位により反転動作させるために、従来では実公平３−９２３４号公報などに開示されているように、反転ばねに主バイメタルと連動する釈放レバーの先端を押し当てて可動板を反転動作させるようにしている。
【０００４】
次に、前記公報に開示されている熱動形過負荷継電器を図５(a),(b) に、またその模式図，およびその反転機構の構造をそれぞれ図６，図７に示す。まず、図５(a) において、１は本体ケース、２は主回路電流が通流するヒートエレメント（図示せず）で加熱される主バイメタル（３相回路の１相のみを示している）、３は主バイメタル２の先端に連繋させたシフタ、４は温度補償バイメタル５と組み合わせて後記の反転機構に対向配置した釈放レバー、６は釈放レバー４の上端に連結した調整リンク、７は調整リンク６の頂部にカム機構を介して連結した整定電流値調整用の調整ダイヤル、８は反転機構の揺動式可動板、９は可動板８に付設した反転ばね（線条の引っ張りコイルばね）、１０は補助接点としての常閉可動接点（ｂ接点）、１１はその固定接点である。
【０００５】
ここで、前記反転機構の可動板８は図７で示すように逆Ｕ字形の金属板からなり、その左右脚部８ａの先端（下端）をナイフエッジとして軸受部材１２に形成したＶ字溝１２ａに突き当てて可動板８を揺動可能に支持している。また、反転ばね９は図５(b) で示すようにばね線条にコイル部９ａ，フック９ｂを形成したもので、可動板８の上端と可動板の下方に配した支持アーム１３との間に両端のフック９ｂを引っ掛けて張架されており、この位置で前記した釈放レバー４の先端部４ａがばね線条の中腹に当接している。なお、図６で１５は常開出力接点（ａ接点）の固定接点、１６は可動接点、１７は可動板８の動きに連動して可動接点１６を開閉するスライダである。
【０００６】
かかる構成で、定常状態では主バイメタル２に連結したシフタ３が右側に後退しており、反転機構の可動板８は反転ばね９のばね力で図示位置に傾動していて、常閉接点１０／１１がＯＮ、常開接点１５／１６がＯＦＦである。この状態から主バイメタル２のヒートエレメント（図示せず）に過電流が流れると、ヒートエレメントの発熱により主バイメタル２が湾曲変位してシフタ３を矢印Ｐ方向に押し、温度補償バイメタル５を介して釈放レバー４を回動させる。これにより、釈放レバー４の先端部４ａが反転ばね９の線条を押し、そのばね線条を「く」字状に撓ませる。この場合に、主回路に過負荷電流が流れて主バイメタル３の湾曲変位量が規定値を超える状態になると、釈放レバー４を介して可動板８が脚部先端を支点に反転動作して常閉接点１０／１１をＯＦＦ、常開接点１５／１６をＯＮに切換え、その接点出力により電磁接触器をトリップ動作させる。なお、前記接点機構のリセットは、図５(a) に示したリセットロッド１４を自動復帰位置，手動復帰位置にセットすることにより行う。
【０００７】
【発明が解決しようとする課題】
ところで、前記構成になる従来の熱動形過負荷継電器では、動作特性，および反転機構の組立性などの面で次記のような問題点がある。
ここで、図６に示した従来構造による各動作特性を図８(a) 〜(c) に示す。(a) 図には主バイメタル２の発生力−変位特性Ａ、可動板８を反転させる際の可動板反力−変位特性Ｂ、および反転ばね９との当接点Ｆ（図６参照）で釈放レバー４に作用する反力−変位特性Ｃを表し、(b) 図には接点機構を開閉位置に駆動する可動板８の発生力−変位特性Ｄ、およびａ，ｂ接点機構の反力−変位特性Ｅを表し、(c) 図は可動板４の反転動作に伴う負荷−変位特性Ｆを表している。
【０００８】
すなわち、主バイメタル２の発生力は、温度上昇により生じた湾曲でシフタ３を押す力であり、反転機構側から主バイメタルの動きが拘束されている変位小の間では発生力が大きく、反転機構が動き初めて主バイメタルの変位が大きくなるにしたがって蓄積していたエネルギーが放出されるので発生力は減少する。一方、反転機構の可動板８を反転駆動するに要するＦ点のばね押反力は、反転ばね９で付勢されている可動板８が定常位置から反転するまでは変位とともに反力が増大し、可動板がデッドポイントを超える，または図８(a) に示した可動板反力Ｂが図８(b) に示したｂ接点反力を下回る（図中のα）の際に逆方向に反転すると急減する。また、接点機構を開閉駆動する際には、反転ばね９でばね付勢されている可動板８の発生力で接点間に接触圧を加え、かつ図示例のａ接点については、その接触子ばねを撓ませて接点を閉じるようにしている。
【０００９】
前記の特性図から判るように、可動板８の発生力−変位特性Ｄと接点機構の開閉駆動に要する反力−変位特性Ｅは略同じ傾向の特性である。これに対して、反転機構の反転動作の前半領域では、主バイメタルの発生力−変位特性Ａと反転ばね９を押す釈放レバー４の反力−変位特性Ｃは増減の向きが相反しており、かつ釈放レバー４に作用する可動板反力は可動板８がデッドポイントを超えたところで零になる。このために、主バイメタル２の発生力は、反転動作の前半では反転ばね９を撓ませて可動板８を反転駆動させるに要する大きな発生力が要求される反面、(a) 図で斜線を付した後半範囲では主バイメタルの発生力（蓄積エネルギー）は駆動力として利用されないことになる。
【００１０】
また、図７のように可動板８の先端をナイフエッジとして軸受部材１２のＶ字溝１２ａに支持したヒンジ構造では、両部部材間のガタ，擦り合いによる摩擦が原因で図８(c) で表すように可動板８が往復反転動作する際の負荷−変位特性Ｆがヒステリシス特性となる。このヒステリシス特性は熱動形過負荷継電器の動作特性に悪影響を及ぼす。また、主バイメタル２はこのヒステリシス特性を見込んだバイメタル特性を確保するように板厚，寸法などを設計する必要があることから、その結果として主バイメタルが大形となり、また過電流検出の設定範囲が狭域となるといった問題が派生する。
【００１１】
さらに、図７に示した従来の反転機構では、可動板８に穿孔した小穴に別部品の引っ張りばね９のフックを引っ掛けており、このために反転機構を組立ロボットなどで自動組立することが困難で、人手作業に頼っているのが現状である。
本発明は上記の点に鑑みなされたものであり、その目的は前記課題を解決して動作特性の改善、並びに反転機構の自動組立が実現可能となるように改良した熱動形過負荷継電器を提供することにある。
【００１２】
【課題を解決するための手段】
上記目的を達成するために、本発明によれば、通電電流の加熱により湾曲変位する主バイメタル、主バイメタルと連動するシフタの変位に従動する釈放レバー、釈放レバーで駆動される接点開閉用の反転機構、および接点機構からなり、主バイメタルの湾曲変位量が規定値を超えた際に反転機構が反転動作して接点を開閉させる熱動形過負荷継電器であり、前記反転機構が脚部の先端を支点として軸受部材に揺動可能に支承さえた可動板と、前記支点を挟んで可動板とその下方に配した支持アームとの間に張架した引っ張りばねとしての反転ばねとしての反転ばねからなるものにおいて、前記釈放レバーを反転機構の可動板の板面に直接押し当てて反転動作を連動させるようにし、また前記の接点機構には、その可動接触子ばねで接点間の接触圧を得るリフトオフ式接点機構を採用して連動する（請求項１）ことにより、主バイメタルの発生力を無駄なく反転機構の反転駆動に有効に活かして動作特性の向上化がはかれるようにする。
【００１３】
また、本発明によれば、反転機構の可動板と軸受部材との間のガタ，摩擦抵抗を排除するために、反転機構の可動板とその軸受部材を弾性ヒンジ部を介して一体に連ねて構成し（請求項２）、さらに、反転機構の自動組立化を実現するために、反転機構の引っ張りばねを板ばねとして可動板と一体に連ねて構成する（請求項３）ものとし、その反転機構をＰＥＴ樹脂などの成形品、またはこれに板ばねを組み合わせた複合形成品として、前記可動板，軸受部材および引っ張りばねを一体に成形するようにする（請求項４）。
【００１４】
【発明の実施の形態】
以下本発明の実施の形態を図１〜図４の実施例で説明する。なお、図１において、図６と対応する部材には同じ符号を付してその詳細な説明は省略する。
すなわち、図１の実施例においては、釈放レバー４にスライド式のレバー４ａを連繋し、このレバー４ａを可動板８の板面に直接押し当てて反転機構を反転動作させるようにしており、この点において図６に示した従来構造とは異なる。また、前記レバー４ａに連動して開閉する常開のａ接点１６には、接触子ばね１６ａの撓み力で固定接点１５との間で所要の接触圧を加え、接点をオフする際には接触子ばね１６ａを撓ませて後退させるようにしたリフトオフ式の接点を採用している。これにより、図示の定常状態（ａ接点ＯＦＦ）ではレバー４ａに対して前記接触子ばね１６ａの撓みばね力が加わることになる。
【００１５】
かかる構成で、主バイメタル２が過電流により湾曲変位すると、シフタ３，釈放レバー４を介してレバー４ａが図示位置から右側に移動し、反転機構の可動板８を直接押して反転動作させる。これにより常閉のｂ接点がＯＦＦとなり、常開のａ接点がＯＮに切り換わる。なお、動作後のリセットは従来と同様にリセット操作ロッド１４により手動もしくは自動で行う。
【００１６】
次に、実施例の構成による動作特性を図２に示す。すなわち、主バイメタル２の発生力−変位特性Ａに対して、釈放レバー４に加わる反力−変位特性Ｇ（ａ接点の負荷−変位特性Ｈと、反転機構の可動板８の負荷−変位特性Ｉとの合特性：Ｇ＝Ｈ＋Ｉ）は図示のようにバイメタルの発生力−変位特性Ａと同じ傾向の特性となる。なお、図中でＰ1 は自動セット時の操作ロッド位置、Ｐ2 は手動セット時の操作ロッド位置を表している。
【００１７】
この動作特性から判るように、従来方式と比べて主バイメタル２の発生エネルギーを殆ど無駄なく有効に活かして反転機構，接点機構を駆動でき、これにより主バイメタル２に要求される機械的発生エネルギーが少なくて済むので、従来問題となっていた過電流検出の設定範囲を大幅に拡大でき、またこれに併せて主バイメタルの小型化が図れる。
【００１８】
次に、本発明の請求項２〜４に対応する実施例を図３，図４で説明する。まず、図３（ａ）の実施例では、反転機構の可動板８と軸受部材１２との間が肉薄な弾性ヒンジ部１８を介して一体に連なるように一体成形された構成になる。この構成によれば、図７に示したナイフエッジとＶ字溝を組み合わせたピボット式のヒンジ構造と比べてガタや反転機構に伴う擦り合いが無くなり、その結果可動板８が反転動作する際の負荷−変位特性Ｆは図３（ｂ）で示すようにヒステリシスが無くなり、図８（ｃ）で示した従来の特性と比べて動作特性を大幅に改善できる。
【００１９】
ここで、前記した弾性ヒンジ部１８を形成するには、可動板８，軸受部材１２の材料としてＣｕ−Ｚｎ−Ａｌ合金もしくはＮｉ−Ｔｉ合金などの弾性限界の大きな金属材料，あるいはＰＥＴ樹脂などが採用できる。なお、発明者等はＰＥＴ樹脂で作製した反転機構についてその耐久試験を行ったところ、６０００回にも及ぶ回数の反転動作テストにも十分耐えることが確認されている。
【００２０】
また、図４に示す実施例は、図３で述べたように可動板８，軸受部材１２および弾性ヒンジ部１８を樹脂製として一体化した構成に加え、さらにばね線条で作られた反転ばね９に代えて、樹脂製の反転ばね１９が可動板８と連なって一体に成形されている。ここで、樹脂製の反転ばね１９は複数の菱形セグメント板（穴明き）１９ａが数珠状に連なり、弾性ヒンジ部１８と同様に反転機構をモールド成形する際に同時成形される。なお、菱形セグメント板１９ａは同一面状に連ねるほか、ジグザク状に屈曲させてもよく、反転機構の組立位置でセグメント１９に引張力を加えた状態で先端のセグメントを支持アーム１３に係止することにより、図７に示した反転機構と線条コイルばねと同様な機能を果たす。
【００２１】
しかも、この実施例によれば、可動板８と反転ばね１９とが一体に形成されているので、図７に示した従来構造のように組立工程で可動板８に穿孔した小穴にばね線条で作られた反転ばね９のフック９ｂを引っ掛ける作業が必要なく、これにより人手作業に頼ることなく自動機による自動組立が可能となる。
【００２２】
【発明の効果】
以上述べたように、本発明の構成によれば、熱動形過負荷継電器の動作特性を改善し、その過電流検出の設定範囲を従来のものと比べて大幅に拡大できるとともに、主バイメタルに要求される機械的な発生エネルギーも小さくて済む。また、反転機構に関して本発明の請求項３〜５の構造を併用することにより、熱動形過負荷継電器の小型，低コスト化が図れるほか、反転機構の自動組立も可能になるなど、動作特性および製作面で優れた効果を発揮する熱動形過負荷継電器を提供することができる。
【図面の簡単な説明】
【図１】本発明の実施例に係る熱動形過負荷継電器を模式的に表した構成図
【図２】図１の構成による熱動形過負荷継電器の動作特性図
【図３】本発明の請求項２に対応する反転気候を示し、（ａ）は反転機構の構成斜視図、（ｂ）は可動板の負荷−変位特性図
【図４】本発明の請求項３に対応する反転気候の構成斜視図
【図５】従来における熱動形過負荷継電器の構成図であり、（ａ）はその製品の組立構造図、（ｂ）は（ａ）図における釈放レバーと反転ばねの拡大斜視図
【図６】図５の構造を模式的に表した図
【図７】図６における反転機構の構成斜視図
【図８】図６の構成による熱動形過負荷継電器の動作特性であり、（ａ）〜（ｃ）はそれぞれ異なる動作特性図[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal overload relay (thermal relay) used in combination with an electromagnetic contactor or the like.
[0002]
[Prior art]
The thermal overload relay described above is composed of a main bimetal that bends and displaces due to heating of the energizing current, a release lever that is driven by the displacement of the shifter that is linked to the main bimetal, a reversing mechanism that opens and closes a contact driven by the release lever, and It consists of a contact mechanism, and when the amount of bending displacement of the main bimetal exceeds a specified value, the reversing mechanism reverses and opens and closes the contact.
[0003]
Here, the reversing mechanism includes a substantially U-shaped movable plate pivotably supported by the bearing member with the tip of the leg as a fulcrum, a movable plate sandwiching the fulcrum, and a support arm disposed below the movable plate. It consists of a reversal spring (wire tension spring). In order to reverse the reversing mechanism by the bending displacement of the main bimetal, the tip of the release lever interlocked with the main bimetal is pushed against the reversing spring as disclosed in Japanese Utility Model Publication No. 3-9234. The movable plate is reversed so as to be reversed.
[0004]
Next, the thermal overload relay disclosed in the publication is shown in FIGS. 5 (a) and 5 (b), and its schematic diagram and the structure of the reversing mechanism are shown in FIGS. 6 and 7, respectively. First, in FIG. 5 (a), 1 is a main body case, 2 is a main bimetal heated by a heat element (not shown) through which a main circuit current flows (only one phase of a three-phase circuit is shown), 3 is a shifter connected to the tip of the main bimetal 2, 4 is a release lever that is combined with the temperature compensating bimetal 5 and is disposed opposite to the reversing mechanism described later, 6 is an adjustment link connected to the upper end of the release lever 4, and 7 is an adjustment link An adjustment dial for adjusting a settling current value connected to the top of 6 via a cam mechanism, 8 is a swinging movable plate of a reversing mechanism, 9 is a reversing spring (wire tension coil spring) attached to the movable plate 8, 10 is a normally closed movable contact (b contact) as an auxiliary contact, and 11 is a fixed contact.
[0005]
Here, the movable plate 8 of the reversing mechanism is made of an inverted U-shaped metal plate as shown in FIG. 7, and a V-shaped groove 12a formed in the bearing member 12 with the tip (lower end) of the left and right leg portions 8a as a knife edge. The movable plate 8 is supported so as to be swingable. The reversing spring 9 is formed by forming a coil portion 9a and a hook 9b on the spring wire as shown in FIG. 5 (b), and between the upper end of the movable plate 8 and the support arm 13 arranged below the movable plate. The tip 9a of the release lever 4 is in contact with the middle of the spring wire at this position. In FIG. 6, 15 is a fixed contact of a normally open output contact (a contact), 16 is a movable contact, and 17 is a slider that opens and closes the movable contact 16 in conjunction with the movement of the movable plate 8.
[0006]
With such a configuration, in a steady state, the shifter 3 connected to the main bimetal 2 is retracted to the right, and the movable plate 8 of the reversing mechanism is tilted to the illustrated position by the spring force of the reversing spring 9, and the normally closed contact 10 / 11 is ON, and the normally open contact 15/16 is OFF. If an overcurrent flows from this state to a heat element (not shown) of the main bimetal 2, the main bimetal 2 is bent and displaced by the heat generated by the heat element, and the shifter 3 is pushed in the direction of the arrow P. The release lever 4 is rotated. Thereby, the front-end | tip part 4a of the release lever 4 pushes the filament of the reversal spring 9, and bends the spring filament in a "<" shape. In this case, when an overload current flows in the main circuit and the amount of bending displacement of the main bimetal 3 exceeds the specified value, the movable plate 8 normally reverses with the tip of the leg portion as a fulcrum via the release lever 4. The closed contact 10/11 is turned off and the normally open contact 15/16 is turned on, and the magnetic contactor is tripped by the contact output. The contact mechanism is reset by setting the reset rod 14 shown in FIG. 5 (a) to the automatic return position and the manual return position.
[0007]
[Problems to be solved by the invention]
By the way, the conventional thermal overload relay having the above-described configuration has the following problems in terms of operating characteristics, assembly of the reversing mechanism, and the like.
Here, the operation characteristics of the conventional structure shown in FIG. 6 are shown in FIGS. (a) In the figure, the generated force-displacement characteristic A of the main bimetal 2, the movable plate reaction force-displacement characteristic B when the movable plate 8 is reversed, and the contact point F with the reversing spring 9 (see FIG. 6) are released. The reaction force-displacement characteristic C acting on the lever 4 is represented, and (b) shows the generated force-displacement characteristic D of the movable plate 8 that drives the contact mechanism to the open / close position, and the reaction force-displacement of the a and b contact mechanisms. The characteristic E is represented, (c) The figure represents the load-displacement characteristic F accompanying the reversing operation of the movable plate 4.
[0008]
That is, the generated force of the main bimetal 2 is a force that pushes the shifter 3 with a curve caused by the temperature rise, and the generated force is large between the small displacements where the movement of the main bimetal is restricted from the reversing mechanism side. Since the accumulated energy is released as the displacement of the main bimetal increases for the first time, the generated force decreases. On the other hand, the spring pushing force at point F required to reversely move the movable plate 8 of the reversing mechanism increases with the displacement until the movable plate 8 biased by the reversing spring 9 is reversed from the steady position. When the movable plate exceeds the dead point, or the movable plate reaction force B shown in FIG. 8 (a) is less than the b contact reaction force shown in FIG. 8 (b) (α in the figure), the direction is reversed. When reversed, it decreases rapidly. When the contact mechanism is opened and closed, contact pressure is applied between the contacts by the generated force of the movable plate 8 biased by the reversing spring 9, and the contact spring of the contact a in the illustrated example. To close the contact.
[0009]
As can be seen from the above characteristic diagram, the generated force-displacement characteristic D of the movable plate 8 and the reaction force-displacement characteristic E required for opening / closing driving of the contact mechanism are characteristics having substantially the same tendency. On the other hand, in the first half region of the reversing operation of the reversing mechanism, the generation force-displacement characteristic A of the main bimetal and the reaction force-displacement characteristic C of the release lever 4 pushing the reversing spring 9 are contradictory to each other. The movable plate reaction force acting on the release lever 4 becomes zero when the movable plate 8 exceeds the dead point. For this reason, the generated force of the main bimetal 2 requires a large generated force required to bend the reversing spring 9 and drive the movable plate 8 in the first half of the reversing operation, but is hatched in FIG. In the latter half range, the generated power (accumulated energy) of the main bimetal is not used as the driving force.
[0010]
Further, as shown in FIG. 7, in the hinge structure in which the tip of the movable plate 8 is supported by the V-shaped groove 12a of the bearing member 12 with the knife edge as shown in FIG. As shown, the load-displacement characteristic F when the movable plate 8 reciprocates is a hysteresis characteristic. This hysteresis characteristic adversely affects the operating characteristics of the thermal overload relay. In addition, the main bimetal 2 needs to be designed with a plate thickness, dimensions, etc. so as to ensure the bimetal characteristics that allow for this hysteresis characteristic. As a result, the main bimetal becomes large and the overcurrent detection setting range The problem that becomes narrow is derived.
[0011]
Furthermore, in the conventional reversing mechanism shown in FIG. 7, the hook of a separate tension spring 9 is hooked in a small hole drilled in the movable plate 8, and therefore it is difficult to automatically assemble the reversing mechanism with an assembly robot or the like. The current situation depends on manual labor.
The present invention has been made in view of the above points, and an object of the present invention is to provide an improved thermal overload relay so that the above problems can be solved and the operation characteristics can be improved, and the automatic assembly of the reversing mechanism can be realized. It is to provide.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a main bimetal that is curved and displaced by heating of an energizing current, a release lever that is driven by a shifter that is interlocked with the main bimetal, and a reversal for opening and closing a contact that is driven by the release lever. And a contact mechanism, and when the amount of bending displacement of the main bimetal exceeds a specified value, the reversing mechanism reverses and opens and closes the contact, and the reversing mechanism is the tip of the leg. From a reversing spring as a reversing spring as a tension spring stretched between a movable plate supported by a bearing member so as to be able to swing on the bearing member as a fulcrum, and a movable plate sandwiching the fulcrum and a support arm disposed below the movable plate in that is, so as to interlock the inversion operation by pressing the release lever directly to the plate surface of the movable plate of the reversing mechanism, the said contact mechanism was or, contact between the contacts at the movable contact spring By interlocking employs a lift-off type contact mechanism to obtain a pressure (claim 1), improvement of effectively utilizing and operating characteristics inversion driving without waste reversing mechanism generation force of the main bimetal is so reduced.
[0013]
Further, according to the present invention, in order to eliminate backlash and frictional resistance between the movable plate of the reversing mechanism and the bearing member, the movable plate of the reversing mechanism and the bearing member are connected together via the elastic hinge portion. configured (claim 2), further, in order to realize the automatic assembly of the reversing mechanism, the tension spring of the reversing mechanism is configured chosen to movable plate integrally as a leaf spring and (claim 3) ones, the inverted mechanism molded articles such as PET resin, or a composite formed article which combines the leaf spring to the movable plate, the bearing member and the tension spring as integrally molded (claim 4).
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to examples shown in FIGS. In FIG. 1, members corresponding to those in FIG. 6 are denoted by the same reference numerals, and detailed description thereof is omitted.
That is, in the embodiment of FIG. 1, a slide type lever 4a is connected to the release lever 4, and the lever 4a is directly pressed against the plate surface of the movable plate 8 so as to reverse the reversing mechanism. This is different from the conventional structure shown in FIG. Further, a normally contacted a contact 16 that opens and closes in conjunction with the lever 4a is subjected to a required contact pressure with the fixed contact 15 by the bending force of the contact spring 16a. A lift-off type contact is adopted in which the child spring 16a is bent and retracted. Thereby, in the illustrated steady state (a contact OFF), the bending spring force of the contact spring 16a is applied to the lever 4a.
[0015]
With such a configuration, when the main bimetal 2 is curved and displaced by an overcurrent, the lever 4a moves to the right side from the illustrated position via the shifter 3 and the release lever 4, and the movable plate 8 of the reversing mechanism is directly pushed to perform the reversing operation. As a result, the normally closed b contact is turned OFF, and the normally open a contact is switched ON. The reset after the operation is manually or automatically performed by the reset operation rod 14 as in the conventional case.
[0016]
Next, the operating characteristics according to the configuration of the embodiment are shown in FIG. That is, the reaction force-displacement characteristic G applied to the release lever 4 with respect to the generated force-displacement characteristic A of the main bimetal 2 (the load-displacement characteristic H of contact a and the load-displacement characteristic I of the movable plate 8 of the reversing mechanism). (G = H + I) has the same tendency as the bimetal generated force-displacement characteristic A as shown in the figure. In the figure, P1 represents the operating rod position during automatic setting, and P2 represents the operating rod position during manual setting.
[0017]
As can be seen from this operating characteristic, the reversing mechanism and the contact mechanism can be driven by effectively utilizing the energy generated in the main bimetal 2 with little waste compared to the conventional method, and the mechanically generated energy required for the main bimetal 2 is thereby reduced. Since it requires less, the setting range of overcurrent detection, which has been a problem in the past, can be greatly expanded, and the size of the main bimetal can be reduced accordingly.
[0018]
Next, an embodiment corresponding to claims 2 to 4 of the present invention will be described with reference to FIGS. First, in the embodiment of FIG. 3A, the movable plate 8 and the bearing member 12 of the reversing mechanism are integrally formed so as to be integrally connected via a thin elastic hinge portion 18. According to this configuration, as compared with the pivot-type hinge structure in which the knife edge and the V-shaped groove shown in FIG. 7 are combined, there is no friction and the friction associated with the reversing mechanism. As a result, when the movable plate 8 is reversed. The load-displacement characteristic F has no hysteresis as shown in FIG. 3B, and the operating characteristics can be greatly improved as compared with the conventional characteristic shown in FIG. 8C.
[0019]
Here, in order to form the elastic hinge portion 18 described above, a metal material having a large elastic limit such as a Cu—Zn—Al alloy or a Ni—Ti alloy or a PET resin is used as the material of the movable plate 8 and the bearing member 12. Can be adopted. The inventors conducted a durability test on a reversing mechanism made of PET resin, and it was confirmed that the reversing operation test as many as 6000 times was sufficiently endured.
[0020]
In addition to the configuration in which the movable plate 8, the bearing member 12, and the elastic hinge portion 18 are integrated as a resin as described in FIG. 3, the embodiment shown in FIG. Instead of 9, a reversal spring 19 made of resin is formed integrally with the movable plate 8. Here, the reversal spring 19 made of resin has a plurality of rhombus segment plates (perforated) 19a connected in a bead shape, and is molded simultaneously with the reversing mechanism in the same manner as the elastic hinge portion 18. In addition, the rhombus segment plate 19a may be bent in a zigzag shape in addition to being connected to the same plane, and the tip segment is locked to the support arm 13 with a tensile force applied to the segment 19 at the assembly position of the reversing mechanism. Thus, the same function as the reversing mechanism and the wire coil spring shown in FIG. 7 is achieved.
[0021]
Moreover, according to this embodiment, since the movable plate 8 and the reversing spring 19 are integrally formed, the spring filament is formed in a small hole drilled in the movable plate 8 in the assembly process as in the conventional structure shown in FIG. There is no need to hook the hook 9b of the reversing spring 9 made in the above, and automatic assembly by an automatic machine becomes possible without relying on manual work.
[0022]
【The invention's effect】
As described above, according to the configuration of the present invention, the operating characteristics of the thermal overload relay can be improved, and the setting range of the overcurrent detection can be greatly expanded as compared with the conventional one, and the main bimetal can be used. Less mechanical energy is required. In addition, by combining the structures of claims 3 to 5 of the present invention with respect to the reversing mechanism, the thermal overload relay can be reduced in size and cost, and the reversing mechanism can be automatically assembled. Further, it is possible to provide a thermal overload relay that exhibits an excellent effect in terms of manufacturing.
[Brief description of the drawings]
FIG. 1 is a configuration diagram schematically showing a thermal overload relay according to an embodiment of the present invention. FIG. 2 is an operation characteristic diagram of a thermal overload relay according to the configuration of FIG. indicates inversion climate corresponding to to claim 2, (a) the structure perspective view of the reversing mechanism, (b) the load of the movable plate - reversing climate corresponding to claim 3 of the displacement characteristic diagram [4] the present invention FIG. 5 is a configuration diagram of a conventional thermal overload relay, (a) is an assembly structure diagram of the product, and (b) is an enlarged perspective view of a release lever and a reversing spring in FIG. FIG. 6 is a diagram schematically showing the structure of FIG. 5. FIG. 7 is a configuration perspective view of the reversing mechanism in FIG. 6. FIG. 8 is an operational characteristic of the thermal overload relay having the configuration of FIG. (A) to (c) are different operating characteristic diagrams.

Claims

It consists of a main bimetal that bends and displaces due to heating of the energizing current, a release lever that follows the shift of the shifter linked to the main bimetal, a contact opening and closing mechanism that is driven by the release lever, and a contact mechanism. Is a thermal overload relay that opens and closes the contact when the reversing mechanism reverses when the value exceeds the specified value, and the reversing mechanism is supported by the bearing member so as to be swingable with the tip of the leg as a fulcrum. a plate, across the year fulcrum movable plate in what consists reversing spring stretched between the support arms of the lower, the inversion operation by pressing directly on the plate surface of the movable plate of the reversing mechanism of the release lever A thermal overload relay, wherein the contact mechanism is interlocked with a lift-off contact mechanism that obtains contact pressure between the contacts with a movable contact spring.

2. The thermal overload relay according to claim 1, wherein the movable plate of the reversing mechanism and the bearing member are integrally connected via an elastic hinge portion.

2. The thermal overload relay according to claim 1, wherein the reversing spring of the reversing mechanism is formed as a leaf spring integrally connected to the movable plate.

4. The thermal overload relay according to claim 2, wherein the reversing mechanism is a resin molded product, and the movable plate, the bearing member and the reversing spring are integrally formed. .