JP3915193B2

JP3915193B2 - Power transmission device

Info

Publication number: JP3915193B2
Application number: JP26891297A
Authority: JP
Inventors: 三起夫松田; 素弘山口; 博康坂本; 学佐伯
Original assignee: Denso Corp; Nippon Soken Inc
Current assignee: Denso Corp; Soken Inc
Priority date: 1997-10-01
Filing date: 1997-10-01
Publication date: 2007-05-16
Anticipated expiration: 2017-10-01
Also published as: JPH11108146A

Description

【０００１】
【発明の属する技術分野】
本発明は過負荷時のトルクリミッターとしての機能を備えた動力伝達装置に関するもので、自動車用空調装置の冷凍サイクルの圧縮機駆動用動力伝達装置として好適なものである。
【０００２】
【従来の技術】
従来、自動車用空調装置における圧縮機として、０容量付近まで容量を変化させることができる可変容量圧縮機を用いる場合には、冷凍サイクルの能力制御のために、圧縮機を断続作動させる必要がなくなる。従って、このような可変容量圧縮機を用いるものでは、エンジンから圧縮機への動力伝達を断続するためのクラッチ機構が不要となる。
【０００３】
一方、圧縮機の焼きつき故障等による圧縮機ロック等の異常が発生した時には、圧縮機駆動機構のベルトに過大なトルクが加わり、ベルトが切損する事態が起こる。特に、自動車の圧縮機駆動機構では、圧縮機以外の種々な補機（バッテリ充電発電機、エンジン冷却水用ウォータポンプ、パワーステアリング用油圧ポンプ等）と共通のベルトにて、エンジンからの動力が伝達されるようになっているので、駆動ベルトが一旦切損すると、自動車の走行不能という重大な故障を引き起こすことになる。
【０００４】
そこで、圧縮機ロック等の過負荷時に伝達トルクが設定値以上に上昇すると、この伝達トルクの上昇に対応して、圧縮機への動力伝達経路を遮断するトルクリミッター機能を付加したものが特開平８−２１０２５０号公報にて提案されている。
この公報記載の中の１つの従来技術では、ベルトが係合され、エンジンの駆動力により回転するプーリに連結された連結基板と、圧縮機回転軸に連結された駆動力受承体とを所定間隔をおいて対向配置するとともに、プーリ側の連結基板と、圧縮機側の駆動力受承体にそれぞれ凹部を形成し、この連結基板の凹部と駆動力受承体の凹部との間にボールを配置している。
【０００５】
そして、このボールを駆動力受承体の凹部に押しつけるバネ力を作用させる弾性手段（圧縮バネ）をプーリ側の連結基板に配設している。通常運転時には、上記両凹部の間にボールを収容した状態を保持することにより、このボールを介して、プーリ側の連結基板から圧縮機側の駆動力受承体に動力が伝達されて圧縮機が作動する。
【０００６】
一方、圧縮機ロック等の過負荷時に伝達トルクが設定値以上に上昇すると、上記弾性手段のバネ力に抗して、負荷トルクの軸方向成分によりボールが駆動力受承体の凹部から離脱する。すると、このボールと圧縮機側の駆動力受承体との係合状態が解除され、プーリ側の連結基板が空回りするようになり、この結果、圧縮機への動力伝達が遮断される。
【０００７】
【発明が解決しようとする課題】
ところで、上記従来技術では、圧縮機への動力伝達の遮断後の状態において、空回りするプーリ側の連結基板上をボールが摺動するので、このボールの摺動部から異音が発生したり、ボールがプーリ側の連結基板に焼きつく恐れもある。
本発明は上記点に鑑みてなされたもので、圧縮機等の従動側機器への動力伝達の遮断後の状態において、ボールの摺動に起因する異音の発生やボールの焼きつきを防止することを目的とする。
【０００８】
【課題を解決するための手段】
上記目的を達成するため、請求項１記載の発明では、駆動側回転部材（１、１１、１２）に備えられた駆動側側板部（１ｃ、１１ａ）の円周方向に、複数の円錐状の第１ボール保持穴（１ｄ）を設け、
従動側回転部材（６）に備えられた従動側側板部（６ｂ）の円周方向には、第１ボール保持穴（１ｄ）に対応して、複数の第２ボール保持穴（６ｃ）を設け、
この第２ボール保持穴（６ｃ）に対して嵌合係止した状態で、第１ボール保持穴（１ｄ）の傾斜壁面に接触可能な複数のボール（８）を備え、
従動側側板部（６ｂ）のうち、第２ボール保持穴（６ｃ）の背面側に凹溝（６ｄ）を形成し、
この凹溝（６ｄ）内に、複数のボール（８）に直接圧接するとともに所定の荷重が加わると形状が反転する皿バネ（９）を配置し、
従動側機器（３）の通常運転時には、皿バネ（９）により複数のボール（８）にバネ力を作用して複数のボール（８）をそれぞれ第１ボール保持穴（１ｄ）の傾斜壁面に所定の荷重で押しつけることにより、駆動側回転部材（１、１１、１２）から複数のボール（８）の嵌合部を経て従動側回転部材（６）に動力が伝達され、
一方、従動側機器（３）の過負荷時には、第１ボール保持穴（１ｄ）の傾斜壁面からボール（８）に加わる軸方向荷重が皿バネ（９）の所定荷重を上回ることにより、皿バネ（９）の形状がボール（８）から離れる方向に反転して、ボール（８）が第１ボール保持穴（１ｄ）の傾斜壁面から離脱し、この離脱したボール（８）が凹溝（６ｄ）内に移動し、これにより、駆動側回転部材（１、１１、１２）から従動側回転部材（６）への動力伝達が遮断されるようにしたことを特徴としている。
また、請求項２記載の発明では、従動側回転部材（６）に備えられた従動側側板部（６ｂ）の円周方向に複数の円錐状の第１ボール保持穴（６ｅ）を設け、
駆動側回転部材（１、１１、１２）に備えられた駆動側側板部（１ｃ、１１ａ）の円周方向には、第１ボール保持穴（６ｅ）に対応して、複数の第２ボール保持穴（１ｇ）を設け、
この第２ボール保持穴（１ｇ）に対して嵌合係止した状態で、第１ボール保持穴（６ｅ）の傾斜壁面に接触可能な複数のボール（８）を備え、
駆動側側板部（１ｃ、１１ａ）のうち、第２ボール保持穴（１ｇ）の背面側に凹溝（１ｆ）を形成し、
この凹溝（１ｆ）内に、複数のボール（８）に直接圧接するとともに所定の荷重が加わると形状が反転する皿バネ（９）を配置し、
従動側機器（３）の通常運転時には、皿バネ（９）により複数のボール（８）にバネ力を作用して複数のボール（８）をそれぞれ第１ボール保持穴（６ｅ）の傾斜壁面に所定の荷重で押しつけることにより、駆動側回転部材（１、１１、１２）から複数のボール（８）の嵌合部を経て従動側回転部材（６）に動力が伝達され、
一方、従動側機器（３）の過負荷時には、第１ボール保持穴（６ｅ）の傾斜壁面からボール（８）に加わる軸方向荷重が皿バネ（９）の所定荷重を上回ることにより、皿バネ（９）の形状がボール（８）から離れる方向に反転して、ボール（８）が第１ボール保持穴（６ｅ）の傾斜壁面から離脱し、この離脱したボール（８）が凹溝（１ｆ）内に移動し、これにより、駆動側回転部材（１、１１、１２）から従動側回転部材（６）への動力伝達が遮断されるようにしたことを特徴としている。
【０００９】
これによると、従動側機器（３）の過負荷時には皿バネ（９）の形状の反転作用により、ボール（８）に作用するバネ力を完全に解放することができ、そのため、動力伝達の遮断作用（トルクリミッター）作用を設定トルクにて確実に行うことができる。
しかも、ボール（８）に作用するバネ力の完全解放により、ボール（８）を円錐状の第１ボール保持穴（１ｄ、６ｅ）の傾斜壁面から離脱して、皿バネ（９）が配置される凹溝（６ｄ、１ｆ）内にボール（８）を移動させることができるので、動力伝達の遮断後の状態においては、ボール（８）の摺動状態が発生せず、そのため、従来技術のようなボール（８）の摺動状態に起因する焼きつきや異音の発生がなく、実用上極めて有利である。
また、請求項１記載の発明によると、動力伝達の遮断後の状態においては、停止状態にある従動側回転部材（６）の凹溝（６ｄ）内にボール（８）を保持することができ、ボール（８）の保持を安定に行うことができる。
【００１２】
特に、請求項３記載の発明では、請求項１または２に記載の動力伝達装置において、駆動側回転部材を、回転駆動源からの回転力がベルトを介して伝達され回転するプーリ（１）と、このプーリ（１）の内周側に間隔をおいて配置された円筒状のロータ（１１）と、このプーリ（１）とロータ（１１）との間を一体に連結する弾性変形可能なゴム部材（１２）とにより構成することを特徴としている。
【００１３】
これによると、ゴム部材（１２）の弾性変形により圧縮機等の従動側機器（３）のトルク変動を吸収できる。従って、トルクリミッター機能とトルク変動吸収機能とを両立させることができる。
なお、上記各手段の括弧内の符号は、後述する実施形態記載の具体的手段との対応関係を示すものである。
【００１４】
【発明の実施の形態】
以下、本発明の実施の形態を図に基づいて説明する。
（第１実施形態）
図１〜図６は本発明を自動車空調用圧縮機の動力伝達装置に適用した第１実施形態を示すものであり、図１は通常の動力伝達状態を示し、図６は過負荷時の動力伝達遮断状態を示している。１は駆動側回転部材をなすプーリで、図示しないベルトを介して自動車エンジン（回転駆動源）から回転力を受けて回転するものである。
【００１５】
このプーリ１は鉄系金属で製作されるものであって、プーリ１には多重Ｖベルトが係合される多重Ｖ溝を持ったプーリ部１ａと、内周円筒部１ｂと、プーリ部１ａと内周円筒部１ｂの間で半径方向に延びる側板部１ｃが一体に備えられている。プーリ１の内周円筒部１ｂにはベアリング２が配置され、このベアリング２によりプーリ１は圧縮機（従動側機器）３のフロントハウジング４の円筒突出部４ａ上に回転自在に支持されている。
【００１６】
５は圧縮機３の回転軸、５ａは軸シール装置で、圧縮機３のフロントハウジング４の円筒突出部４ａの内周側と回転軸５との間に配置され、圧縮機３の内部から外部へ冷媒が漏れるのを防止するためのものである。
６は従動側回転部材をなすハブで、内周円筒部６ａと、この内周円筒部６ａの一端部（反圧縮機側の端部）から半径方向外側へ延びる円板状の側板部６ｂとを有する形状に鉄系金属で形成されている。このハブ６の内周円筒部６ａは回転軸５に対してインボリュートスプライン結合等により回転方向に回り止めして嵌合し、かつボルト７により回転軸５の先端部に一体に締結されている。
【００１７】
プーリ１の側板部１ｃは、ハブ６の側板部６ｂに対向するように配置され、この側板部１ｃには図３に拡大図示するように円錐状の第１ボール保持穴１ｄが形成されている。このボール保持穴１ｄの円錐形はハブ６の側板部６ｂ側の径が大きく、圧縮機３側へ行くにつれて小さくなるように設定されている。このボール保持穴１ｄは金属製のボール８を保持するもので、ボール保持穴１ｄの円錐形の最大径はボール８の径より若干大きく設定され、円錐形の傾斜壁面の途中部位（図３参照）にボール８が接触する。
【００１８】
このボール８は、図２に示すように回転軸５を中心とする円周方向に略等間隔で複数（本例では８個）配置されており、従って、第１ボール保持穴１ｄもボール８に対応してプーリ１の側板部１ｃの円周方向に複数（本例では８個）配置されている。
一方、ハブ６の側板部６ｂの外周側部位は厚肉状に形成されており、この側板部６ｂの外周側厚肉部には、前記した第１ボール保持穴１ｄと半径方向の同一位置（図１の半径ｒの位置）に、第１ボール保持穴１ｄと対向するように円筒状の第２ボール保持穴６ｃが開けてある。この第２ボール保持穴６ｃもボール８に対応してハブ６の側板部６ｂの円周方向に複数（本例では８個）配置されている。この円筒状の第２ボール保持穴６ｃの内径は図３に拡大図示するように金属製のボール８の外径より若干大きくして、ボール８を嵌合係止できるようにしてある。
【００１９】
また、ハブ６の側板部６ｂには第２ボール保持穴６ｃの背面側（反圧縮機側）に環状の凹溝６ｄが形成されており、この環状の凹溝６ｄの半径方向の幅寸法は図３に示すようにボール８の径より十分大きくしてある。そして、この環状の凹溝６ｄ内には所定の荷重にて反転する特性を持つ弾性部材として皿バネ９が配置されている。この皿バネ９の内周部はサークリップ１０にて環状の凹溝６ｄ内周部に位置決めして保持されている。また、皿バネ９の外周部はボール８に圧接してボール８を第１ボール保持穴１ｄの傾斜壁面（円錐面）に所定のバネ荷重Ｆｓにて押しつけるようになっている。
【００２０】
なお、円錐状の第１ボール保持穴１ｄの頂部側（小径側）には円筒状穴１ｅ（図３）が形成してある。この円筒状穴１ｅは、ボール８の球面形状が第１ボール保持穴１ｄの円錐頂部側に小面積で当接するのを防止するためのものである。
次に、上記構成において第１実施形態の作動を説明する。車両エンジンが運転されると、車両エンジンのクランクプーリからの駆動力が図示しないベルトを介してプーリ１に伝達され、プーリ１がベアリング２上で回転する。ここで、ボール８が皿バネ９のバネ荷重Ｆｓにて第１ボール保持穴１ｄの傾斜壁面に押しつけられているので、ハブ６の側板部６ｂの円筒状の第２ボール保持穴６ｃ内にボール８が嵌合係止された状態が保持される。
【００２１】
これにより、駆動力はプーリ１からボール８の嵌合係止部を経てハブ６に伝達され、ハブ６から回転軸５に伝達されて圧縮機３が作動する。
ところで、ボール８には図３に示すように、エンジンからの駆動トルクＴに応じて第１ボール保持穴１ｄの傾斜壁面で発生する軸方向成分の荷重Ｆｂｏと、円錐バネ９によるバネ荷重Ｆｓが作用する。
【００２２】
ボール１個当たりに作用する軸方向荷重をＦｂｏとし、全体の軸方向荷重をＦｂとし、円錐状の第１ボール保持穴１ｄの壁面の傾斜角をθとし、円錐状の第１ボール保持穴１ｄの傾斜壁面による回転方向成分の荷重をＦｔとし、ボール８の数をＮとすると、軸方向荷重ＦｂｏおよびＦｂは次の数式１で表すことができる。
【００２３】
【数１】
Ｆｂ＝Ｎ・Ｆｂｏ
Ｆｂｏ＝Ｆｔ・ｔａｎθ
そして、回転方向成分の荷重をＦｔは、ボール８の配置部位の半径であるピッチ半径をｒ（図１参照）とすると、次の数式２で表すことができる。
【００２４】
【数２】
Ｆｔ＝Ｔ／（ｒ・Ｎ）
一方、皿バネ９は、一般的によく知られているように、所定の荷重Ｆｍを越えた荷重が作用すると、その皿形状が反転する特性を有するものであり、本例の皿バネ９は図５に示すように、所定の荷重Ｆｍ＝６０Ｋｇｆ以上の荷重が作用すると、皿形状が反転して大きく変形するように設定されている。また、ボール８の直径は、本例では、皿バネ９の荷重特性が図５において負の特性となる領域、具体的には、図５のＤ点で示す３ｍｍ設定されている。
【００２５】
従って、図１の動力伝達装置の組付時に、皿バネ９の変形量を約０．５ｍｍとして、皿バネ９に５０Ｋｇｆの荷重（図５のＡ点）を与えるようにしておけば、通常の運転状態では、ボール８は図４（ａ）に示すように、皿バネ９のバネ荷重Ｆｓにて第１ボール保持穴１ｄの傾斜壁面に押しつけられ、ボール８を介してプーリ１からハブ６に動力が伝達される。
【００２６】
しかし、圧縮機３がロック等を起こして，過大な負荷トルクがボール８の嵌合部に作用すると、第１ボール保持穴１ｄの傾斜壁面で発生する軸方向成分の荷重Ｆｂが皿バネ９の反転荷重の設定値Ｆｍ（６０Ｋｇｆ）を上回るので、この軸方向荷重Ｆｂにより皿バネ９が反転する。この皿バネ９の反転状態は図５ではＣ点となる。
【００２７】
そして、皿バネ９の反転によって、ボール８は図４（ａ）の状態から図４（ｂ）、図４（ｃ）の中間状態を経由して最終的には図６に示すように、第１、第２ボール保持穴１ｄ、６ｃから完全に離脱して、ハブ６の環状凹溝６ｄ内に落ち込む。この結果、ボール８を介したプーリ１とハブ６との円周方向の係止状態が解除されるため、プーリ１がハブ６から離脱して空転し、ハブ６側への動力伝達が遮断される。
【００２８】
そして、一旦、動力伝達が遮断された後では、ハブ６は停止状態となり、この停止状態のハブ６の環状凹溝６ｄ内にボール８が保持されるので、動力伝達の遮断状態を以後確実に維持できるとともに、ボール８は回転状態を保つプーリ１側から完全に離脱しているので、ボール８の焼きつき等の恐れが全くない。また、ボール８の摺動による異音を発生することもない。
【００２９】
なお、ボール８、第１、第２ボール保持穴１ｄ、６ｃ、皿バネ９等の表面には、錆付き防止、耐食性向上、摩擦低減等の目的のために、適宜の表面処理（例えば、フッ素樹脂コーティング等）を施してもよい。
（第２実施形態）
図７は第２実施形態を示すもので、第２実施形態では、第１実施形態のプーリ１を、プーリ１と円筒形状のロータ１１に分割し、プーリ１のプーリ部１ａの内周側に所定間隔を開けてロータ１１を同心状に配置するとともに、このプーリ１のプーリ部１ａの内周側とロータ１１の外周側との間を、弾性変形可能なゴム部材１２により一体に連結している。
【００３０】
ここで、ゴム部材１２は円筒状に１つに繋がった形状でも、円周方向に複数に分割された形状でもよく、ゴム部材１２はプーリ部１ａの内周側とロータ１１の外周側に焼き付き接着等の方法で固着されている。このゴム部材１２の弾性変形により圧縮機３のトルク変動を減衰、吸収し、騒音を低減する。
そして、第２実施形態では、ロータ１１の半径方向内側に延びる側板部１１ａに、第１実施形態の円錐状の第１ボール保持穴１ｄ、円筒状穴１ｅを設けて、サークリップ１０により保持した皿バネ９のバネ荷重Ｆｓにてボール８をプーリ１側の円錐状の第１ボール保持穴１ｄの傾斜壁面に押しつける点は第１実施形態と同じである。
【００３１】
従って、第２実施形態によると、第１実施形態と同じ作動機構にて圧縮機３の過負荷時のトルクリミッター機能を果たすことができ、しかも、圧縮機３の通常運転時にはゴム部材１２の弾性変形によりトルク変動吸収機能をも発揮できる。よって、第２実施形態では、圧縮機ロックのような過負荷時のトルクリミッター機能と、通常運転時におけるトルク変動吸収機能とを両立することができる。
【００３２】
（第３実施形態）
図８は第３実施形態を示すもので、ハブ６の環状凹溝６ｄの外周部をテーパ面１３としている。このテーパ面１３はプーリ１側から遠ざかるにつれて径寸法が大きくなるように傾斜している。これにより、動力伝達の遮断時に、図８の上側位置から下側位置に落下したボール８をテーパ面１３の傾斜に沿って反プーリ１側へ移行させて、ボール８を図８の下側に示すように皿バネ９の外周先端部とテーパ面１３との間で挟み込むことができる。これにより、ボール８のがたつきを確実に防止するようにしたものである。
【００３３】
（第４実施形態）
図９は第４実施形態を示すもので、ハブ６の環状凹溝６ｄの外周部にサークリップ１４を配置することにより、動力伝達の遮断時に、図９の上側位置から下側位置に落下したボール８をサークリップ１４と環状凹溝６ｄの底面部との間で保持して、ボール８のがたつきを確実に防止するようにしたものである。
【００３４】
（第５実施形態）
図１０、１１は第５実施形態を示すもので、皿バネ９の先端部とボール８との間にリング状の保持板１５を介在するようにしたもので、この保持板１５にはボール８を押圧する部位に、ボール８の半径と同一半径を有する球面状の凹部１５ａを形成し、この球面状の凹部１５ａがボール８の表面に面接触するようにしたものである。これにより、ボール８表面での接触部の面圧を低下できるので、トルクリミッタ作動の信頼性を向上できる。
【００３５】
（第６実施形態）
図１２、１３は第６実施形態を示すもので、上記した各実施形態ではいずれもハブ６側に環状凹溝６ｄを形成して、この環状凹溝６ｄ内に皿バネ９を配置しているが、第６実施形態ではプーリ１の側板部１ｃに環状凹溝１ｆを形成し、このプーリ１側の環状凹溝１ｆ内に皿バネ９をサークリップ１０により位置決めして配置するとともに、プーリ１の側板部１ｃに円筒状のボール保持穴１ｇ（上述の円筒状の第２ボール保持穴６ｃに相当）を設けている。また、環状凹溝１ｆの外周部には第３実施形態と同様のテーパ面１３を設けている。
【００３６】
一方、ハブ６の側板部６ｂには、円錐状のボール保持穴６ｅ（上述の円錐状の第１ボール保持穴１ｄに相当）および円筒状穴６ｆ（上述の円筒状穴１ｅに相当）を設けている。
第６実施形態によると、圧縮機ロック時等の過負荷時には、皿バネ９の反転によりボール８がプーリ１の環状凹溝１ｆ内に落ち込んで、プーリ１からハブ６への動力伝達が遮断される。動力伝達の遮断後、ボール８は回転状態にあるプーリ１側に保持されるので、ボール８は遠心力にて環状凹溝１ｆ内の外周部に付着する。そして、ボール８は、環状凹溝１ｆ内の外周部のテーパ面１３に沿ってハブ６から遠ざかる方向へ移動するので、第３実施形態と同様に、皿バネ９の外周先端部とテーパ面１３との間でボール８を挟み込むことができる。これにより、ボール８のがたつきを確実に防止できる。
【００３７】
（他の実施形態）
なお、上記各実施形態では、いずれも反転作用を有する弾性部材として皿バネ９を用いているが、皿バネ９に限らず、反転作用を有する弾性部材であれば、どのようなものでも使用できる。
また、本発明は自動車用空調装置の圧縮機への動力伝達装置に限らず、種々な用途のものに広く適用可能である。
【図面の簡単な説明】
【図１】本発明の第１実施形態を示す縦断面図で、通常運転時の状態を示す。
【図２】図１の正面図である。
【図３】図１の要部拡大断面図である。
【図４】第１実施形態において、過負荷運転時におけるトルクリミッタ−作動の経過を説明する説明図である。
【図５】第１実施形態において用いる皿バネの特性図である。
【図６】第１実施形態において過負荷運転時のトルクリミッタ−作動後の動力遮断状態を示す縦断面図である。
【図７】本発明の第２実施形態を示す縦断面図で、通常運転時の状態を示す。
【図８】本発明の第３実施形態を示す縦断面図で、トルクリミッタ−作動後の動力遮断状態を示す。
【図９】本発明の第４実施形態を示す縦断面図で、トルクリミッタ−作動後の動力遮断状態を示す。
【図１０】本発明の第５実施形態を示す縦断面図で、通常運転時の状態を示す。
【図１１】第５実施形態において用いる保持板の正面図である。
【図１２】本発明の第６実施形態を示す縦断面図で、通常運転時の状態を示す。
【図１３】図１２の正面図である。
【符号の説明】
１…プーリ（駆動側回転部材）、１ｃ…側板部、
１ｄ、６ｅ…円錐状の第１ボール保持穴、、３…圧縮機、
５…回転軸、６…ハブ（従動側回転部材）、６ｂ…側板部、
６ｃ、１ｇ…円筒状の第２ボール保持穴、６ｄ、１ｆ…凹溝、８…ボール、
９…皿バネ（弾性手段）。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power transmission device having a function as a torque limiter at the time of overload, and is suitable as a power transmission device for driving a compressor of a refrigeration cycle of an automotive air conditioner.
[0002]
[Prior art]
Conventionally, when a variable capacity compressor capable of changing the capacity to near 0 capacity is used as a compressor in an automobile air conditioner, it is not necessary to intermittently operate the compressor for capacity control of the refrigeration cycle. . Therefore, in the case of using such a variable capacity compressor, a clutch mechanism for intermittently transmitting power from the engine to the compressor becomes unnecessary.
[0003]
On the other hand, when an abnormality such as a compressor lock due to a burn-in failure of the compressor or the like occurs, an excessive torque is applied to the belt of the compressor drive mechanism and the belt is broken. In particular, in the compressor drive mechanism of an automobile, the power from the engine is received by a common belt with various auxiliary devices other than the compressor (battery charging generator, water pump for engine cooling water, hydraulic pump for power steering, etc.). Since it is transmitted, once the drive belt is broken, it causes a serious failure that the automobile cannot run.
[0004]
Therefore, when the transmission torque rises above the set value during overload such as compressor lock, a torque limiter function that cuts off the power transmission path to the compressor is added in response to this increase in transmission torque. This is proposed in Japanese Laid-Open Patent Publication No. 8-210250.
In one prior art described in this publication, a belt is engaged and a connecting substrate connected to a pulley that rotates by a driving force of an engine, and a driving force receiver connected to a compressor rotating shaft are provided in a predetermined manner. The concavities are arranged opposite to each other, and concave portions are respectively formed in the pulley-side connecting board and the compressor-side driving force receiving body, and a ball is formed between the concave portion of the connecting board and the driving force receiving body. Is arranged.
[0005]
And the elastic means (compression spring) which applies the spring force which presses this ball | bowl against the recessed part of a driving force receiving body is arrange | positioned at the connection board | substrate by the side of a pulley. During normal operation, the state in which the ball is accommodated between the two recesses is maintained, so that the power is transmitted from the pulley-side connecting substrate to the compressor-side driving force receiving body via the ball. Operates.
[0006]
On the other hand, when the transmission torque rises to a set value or more during an overload such as a compressor lock, the ball separates from the recess of the driving force receiving body by the axial component of the load torque against the spring force of the elastic means. . Then, the engagement state between the ball and the driving force receiving body on the compressor side is released, and the connecting board on the pulley side is idled. As a result, power transmission to the compressor is interrupted.
[0007]
[Problems to be solved by the invention]
By the way, in the above prior art, in a state after the transmission of power to the compressor is interrupted, the ball slides on the connecting board on the idle pulley side, so that abnormal noise is generated from the sliding portion of the ball, There is also a risk that the balls will burn onto the connecting board on the pulley side.
The present invention has been made in view of the above points, and in the state after the transmission of power to a driven device such as a compressor is interrupted, the generation of abnormal noise due to the sliding of the ball and the burning of the ball are prevented. For the purpose.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a plurality of conical shapes are provided in the circumferential direction of the drive side plate (1c, 11a) provided in the drive side rotating member (1, 11, 12). Providing a first ball holding hole ( 1d );
A plurality of second ball holding holes ( 6c ) are provided corresponding to the first ball holding holes ( 1d ) in the circumferential direction of the driven side plate portion (6 b) provided in the driven side rotating member (6). ,
A plurality of balls (8) capable of contacting the inclined wall surface of the first ball holding hole ( 1d ) in a state of being fitted and locked to the second ball holding hole ( 6c ) ,
A concave groove (6d) is formed on the back side of the second ball holding hole (6c) in the driven side plate portion (6b),
In this concave groove (6d), a disc spring (9) that is in direct contact with the plurality of balls (8) and whose shape is reversed when a predetermined load is applied is arranged,
During normal operation of the driven device (3), a spring force is applied to the plurality of balls (8) by the disc spring (9) to place the plurality of balls (8) on the inclined wall surfaces of the first ball holding holes ( 1d ). By pressing with a predetermined load, power is transmitted from the driving side rotating member (1, 11, 12) to the driven side rotating member (6) through the fitting portions of the plurality of balls (8),
On the other hand, when an overload of the driven equipment (3), by an axial load applied from the inclined wall surface of the first ball holding hole (1d) to the ball (8) is above the predetermined load of the disc spring (9), disc springs The shape of (9) is reversed in the direction away from the ball (8), the ball (8) is released from the inclined wall surface of the first ball holding hole ( 1d ), and the released ball (8) is a concave groove (6d ), So that power transmission from the driving side rotating member (1, 11, 12) to the driven side rotating member (6) is cut off.
In the invention according to claim 2, a plurality of conical first ball holding holes (6e) are provided in the circumferential direction of the driven side plate portion (6b) provided in the driven side rotating member (6).
In the circumferential direction of the drive side plate portions (1c, 11a) provided in the drive side rotating member (1, 11, 12), a plurality of second ball holdings corresponding to the first ball holding holes (6e). Hole (1g),
A plurality of balls (8) capable of contacting the inclined wall surface of the first ball holding hole (6e) in a state of being fitted and locked to the second ball holding hole (1g),
A concave groove (1f) is formed on the back side of the second ball holding hole (1g) in the drive side plate portion (1c, 11a),
In this concave groove (1f), a disc spring (9) that is in direct contact with the plurality of balls (8) and whose shape is reversed when a predetermined load is applied is arranged,
During normal operation of the driven device (3), a spring force is applied to the plurality of balls (8) by the disc springs (9) to place the plurality of balls (8) on the inclined wall surfaces of the first ball holding holes (6e). By pressing with a predetermined load, power is transmitted from the driving side rotating member (1, 11, 12) to the driven side rotating member (6) through the fitting portions of the plurality of balls (8),
On the other hand, when the driven device (3) is overloaded, the axial load applied to the ball (8) from the inclined wall surface of the first ball holding hole (6e) exceeds the predetermined load of the disc spring (9). The shape of (9) is reversed in the direction away from the ball (8), the ball (8) is detached from the inclined wall surface of the first ball holding hole (6e), and the separated ball (8) is recessed into the groove (1f ), So that power transmission from the driving side rotating member (1, 11, 12) to the driven side rotating member (6) is cut off.
[0009]
According to this, when the driven device (3) is overloaded, the spring force acting on the ball (8) can be completely released by the reversing action of the shape of the disc spring (9). The action (torque limiter) can be reliably performed at the set torque.
Moreover, by completely releasing the spring force acting on the ball (8), the ball (8) is detached from the inclined wall surface of the conical first ball holding hole (1d, 6e), and the disc spring (9) is arranged. Since the ball (8) can be moved into the concave grooves (6d, 1f), the sliding state of the ball (8) does not occur in the state after the power transmission is interrupted. There is no occurrence of seizure or abnormal noise due to the sliding state of the ball (8), which is extremely advantageous in practical use.
According to the first aspect of the present invention, the ball (8) can be held in the concave groove (6d) of the driven side rotating member (6) in a stopped state in a state after the power transmission is interrupted. The ball (8) can be held stably.
[0012]
In particular, in the invention according to claim 3, in the power transmission device according to claim 1 or 2, the driving side rotating member is connected to the pulley (1) which rotates by the rotational force transmitted from the rotational driving source via the belt. A cylindrical rotor (11) disposed at an interval on the inner peripheral side of the pulley (1), and an elastically deformable rubber for integrally connecting the pulley (1) and the rotor (11) It is characterized by comprising with a member (12).
[0013]
According to this, the torque fluctuation of the driven device (3) such as a compressor can be absorbed by the elastic deformation of the rubber member (12). Therefore, both the torque limiter function and the torque fluctuation absorbing function can be achieved.
In addition, the code | symbol in the bracket | parenthesis of each said means shows a corresponding relationship with the specific means of embodiment description later mentioned.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
1 to 6 show a first embodiment in which the present invention is applied to a power transmission device for a compressor for automobile air conditioning. FIG. 1 shows a normal power transmission state, and FIG. 6 shows power during overload. The transmission interruption state is shown. Reference numeral 1 denotes a pulley that constitutes a drive-side rotating member, which rotates by receiving a rotational force from an automobile engine (rotation drive source) via a belt (not shown).
[0015]
The pulley 1 is made of an iron-based metal, and the pulley 1 has a pulley portion 1a having a multiple V groove with which a multiple V belt is engaged, an inner peripheral cylindrical portion 1b, a pulley portion 1a, Side plate portions 1c extending in the radial direction between the inner peripheral cylindrical portions 1b are integrally provided. A bearing 2 is disposed on the inner peripheral cylindrical portion 1 b of the pulley 1, and the pulley 1 is rotatably supported by the bearing 2 on a cylindrical protruding portion 4 a of the front housing 4 of the compressor (driven device) 3.
[0016]
Reference numeral 5 denotes a rotating shaft of the compressor 3, and 5 a a shaft seal device, which is disposed between the inner peripheral side of the cylindrical protrusion 4 a of the front housing 4 of the compressor 3 and the rotating shaft 5. This is to prevent the refrigerant from leaking.
Reference numeral 6 denotes a hub constituting a driven side rotating member, an inner peripheral cylindrical portion 6a, and a disk-shaped side plate portion 6b extending radially outward from one end portion (end portion on the anti-compressor side) of the inner peripheral cylindrical portion 6a; It is formed of an iron-based metal in a shape having The inner peripheral cylindrical portion 6a of the hub 6 is fitted to the rotating shaft 5 while being prevented from rotating in the rotating direction by involute spline coupling or the like, and is fastened integrally to the distal end portion of the rotating shaft 5 by a bolt 7.
[0017]
The side plate portion 1c of the pulley 1 is disposed so as to face the side plate portion 6b of the hub 6. The side plate portion 1c is formed with a conical first ball holding hole 1d as shown in an enlarged view in FIG. . The conical shape of the ball holding hole 1d is set so that the diameter on the side plate portion 6b side of the hub 6 is large and becomes smaller toward the compressor 3 side. The ball holding hole 1d holds the metal ball 8. The maximum diameter of the conical shape of the ball holding hole 1d is set to be slightly larger than the diameter of the ball 8, and an intermediate portion of the conical inclined wall surface (see FIG. 3). ) Comes into contact with the ball 8.
[0018]
As shown in FIG. 2, a plurality of (eight in the present example) balls 8 are arranged at substantially equal intervals in the circumferential direction around the rotation shaft 5. A plurality (eight in this example) are arranged in the circumferential direction of the side plate portion 1 c of the pulley 1.
On the other hand, the outer peripheral side portion of the side plate portion 6b of the hub 6 is formed thick, and the outer peripheral side thick portion of the side plate portion 6b has the same radial position as the first ball holding hole 1d ( A cylindrical second ball holding hole 6c is formed at a position of a radius r in FIG. 1 so as to face the first ball holding hole 1d. A plurality (eight in this example) of the second ball holding holes 6 c are also arranged in the circumferential direction of the side plate portion 6 b of the hub 6 corresponding to the balls 8. The inner diameter of the cylindrical second ball holding hole 6c is slightly larger than the outer diameter of the metal ball 8 as shown in an enlarged view in FIG. 3, so that the ball 8 can be fitted and locked.
[0019]
Further, the side plate portion 6b of the hub 6 has an annular groove 6d formed on the back side (the anti-compressor side) of the second ball holding hole 6c, and the radial width dimension of the annular groove 6d is as follows. As shown in FIG. 3, it is sufficiently larger than the diameter of the ball 8. A disc spring 9 is disposed in the annular concave groove 6d as an elastic member having a characteristic of reversing with a predetermined load. The inner peripheral portion of the disc spring 9 is positioned and held by the circlip 10 on the inner peripheral portion of the annular groove 6d. The outer peripheral portion of the disc spring 9 is pressed against the ball 8 to press the ball 8 against the inclined wall surface (conical surface) of the first ball holding hole 1d with a predetermined spring load Fs.
[0020]
A cylindrical hole 1e (FIG. 3) is formed on the top side (small diameter side) of the conical first ball holding hole 1d. The cylindrical hole 1e is for preventing the spherical shape of the ball 8 from coming into contact with the top of the cone of the first ball holding hole 1d with a small area.
Next, the operation of the first embodiment in the above configuration will be described. When the vehicle engine is operated, the driving force from the crank pulley of the vehicle engine is transmitted to the pulley 1 via a belt (not shown), and the pulley 1 rotates on the bearing 2. Here, since the ball 8 is pressed against the inclined wall surface of the first ball holding hole 1d by the spring load Fs of the disc spring 9, the ball is placed in the cylindrical second ball holding hole 6c of the side plate portion 6b of the hub 6. The state in which 8 is fitted and locked is maintained.
[0021]
As a result, the driving force is transmitted from the pulley 1 to the hub 6 through the fitting and locking portion of the ball 8, and is transmitted from the hub 6 to the rotating shaft 5 to operate the compressor 3.
Incidentally, as shown in FIG. 3, the ball 8 has an axial component load Fbo generated on the inclined wall surface of the first ball holding hole 1d in accordance with the driving torque T from the engine and a spring load Fs by the conical spring 9. Works.
[0022]
The axial load acting on per ball and Fbo, the axial load of the whole and Fb, the inclination angle of the wall surface of the conical first ball holding hole 1d and theta, conical first ball holding hole 1d The axial loads Fbo and Fb can be expressed by the following Equation 1, where Ft is the load in the rotational direction due to the inclined wall surface, and N is the number of balls 8.
[0023]
[Expression 1]
Fb = N · Fbo
Fbo = Ft · tanθ
The load of the rotation direction component Ft can be expressed by the following mathematical formula 2, where r (see FIG. 1) is the pitch radius, which is the radius of the portion where the ball 8 is arranged.
[0024]
[Expression 2]
Ft = T / (r · N)
On the other hand, as is generally well known, the disc spring 9 has a characteristic that its disc shape is reversed when a load exceeding a predetermined load Fm is applied. As shown in FIG. 5, when a predetermined load Fm = 60 kgf or more is applied, the dish shape is set to be reversed and greatly deformed. Further, in this example, the diameter of the ball 8 is set to a region where the load characteristic of the disc spring 9 is a negative characteristic in FIG. 5, specifically, 3 mm indicated by a point D in FIG.
[0025]
Therefore, when the power transmission device of FIG. 1 is assembled, if the amount of deformation of the disc spring 9 is about 0.5 mm and a load of 50 kgf is applied to the disc spring 9 (point A in FIG. 5), In the driving state, the ball 8 is pressed against the inclined wall surface of the first ball holding hole 1d by the spring load Fs of the disc spring 9 as shown in FIG. Power is transmitted.
[0026]
However, when the compressor 3 is locked or the like and an excessive load torque acts on the fitting portion of the ball 8, the axial component load Fb generated on the inclined wall surface of the first ball holding hole 1d is Since it exceeds the set value Fm (60 Kgf) of the reverse load, the disc spring 9 is reversed by this axial load Fb. The inverted state of the disc spring 9 is point C in FIG.
[0027]
Then, by the reversal of the disc spring 9, the ball 8 passes through the intermediate state shown in FIG. 4 (b) and FIG. 4 (c) from the state shown in FIG. 1. It completely leaves the second ball holding holes 1d, 6c and falls into the annular groove 6d of the hub 6. As a result, since the circumferential locking state of the pulley 1 and the hub 6 via the ball 8 is released, the pulley 1 is detached from the hub 6 and idles, and the power transmission to the hub 6 side is interrupted. The
[0028]
Then, once the power transmission is interrupted, the hub 6 is stopped, and the ball 8 is held in the annular groove 6d of the hub 6 in the stopped state. In addition to being able to maintain, the ball 8 is completely detached from the pulley 1 side that keeps rotating, so there is no fear of the ball 8 being seized. Further, no abnormal noise is generated by the sliding of the ball 8.
[0029]
The surfaces of the balls 8, the first and second ball holding holes 1d and 6c, the disc spring 9 and the like are subjected to appropriate surface treatment (for example, fluorine treatment) for the purpose of preventing rusting, improving corrosion resistance, reducing friction, and the like. A resin coating or the like may be applied.
(Second Embodiment)
FIG. 7 shows the second embodiment. In the second embodiment, the pulley 1 of the first embodiment is divided into a pulley 1 and a cylindrical rotor 11, and the pulley 1 is arranged on the inner peripheral side of the pulley 1 a. The rotor 11 is arranged concentrically at a predetermined interval, and the inner peripheral side of the pulley portion 1a of the pulley 1 and the outer peripheral side of the rotor 11 are integrally connected by an elastically deformable rubber member 12. Yes.
[0030]
Here, the rubber member 12 may be formed in a single cylindrical shape or divided into a plurality of portions in the circumferential direction, and the rubber member 12 is seized on the inner peripheral side of the pulley portion 1 a and the outer peripheral side of the rotor 11. It is fixed by a method such as adhesion. The elastic deformation of the rubber member 12 attenuates and absorbs torque fluctuations of the compressor 3 to reduce noise.
In the second embodiment, the conical first ball holding hole 1d and the cylindrical hole 1e of the first embodiment are provided in the side plate portion 11a extending radially inward of the rotor 11, and held by the circlip 10. The point that the ball 8 is pressed against the inclined wall surface of the conical first ball holding hole 1d on the pulley 1 side by the spring load Fs of the disc spring 9 is the same as in the first embodiment.
[0031]
Therefore, according to the second embodiment, the torque limiter function when the compressor 3 is overloaded can be fulfilled by the same operation mechanism as that of the first embodiment, and the elasticity of the rubber member 12 can be achieved during normal operation of the compressor 3. The torque fluctuation absorbing function can also be exhibited by the deformation. Therefore, in 2nd Embodiment, the torque limiter function at the time of an overload like a compressor lock | rock and the torque fluctuation absorption function at the time of normal operation can be made compatible.
[0032]
(Third embodiment)
FIG. 8 shows a third embodiment in which the outer peripheral portion of the annular groove 6 d of the hub 6 is a tapered surface 13. The tapered surface 13 is inclined so that the diameter dimension increases as the distance from the pulley 1 increases. As a result, when the power transmission is interrupted, the ball 8 dropped from the upper position to the lower position in FIG. 8 is moved to the side opposite to the pulley 1 along the inclination of the taper surface 13, and the ball 8 is moved to the lower side in FIG. As shown, it can be sandwiched between the outer peripheral tip of the disc spring 9 and the tapered surface 13. As a result, rattling of the ball 8 is reliably prevented.
[0033]
(Fourth embodiment)
FIG. 9 shows the fourth embodiment, and the circlip 14 is arranged on the outer peripheral portion of the annular groove 6d of the hub 6 so that it drops from the upper position to the lower position in FIG. 9 when the power transmission is interrupted. The ball 8 is held between the circlip 14 and the bottom surface portion of the annular groove 6d so as to reliably prevent the ball 8 from rattling.
[0034]
(Fifth embodiment)
10 and 11 show a fifth embodiment, in which a ring-shaped holding plate 15 is interposed between the tip of the disc spring 9 and the ball 8. A spherical concave portion 15 a having the same radius as the radius of the ball 8 is formed in a portion where the ball is pressed, and the spherical concave portion 15 a is in surface contact with the surface of the ball 8. Thereby, since the surface pressure of the contact portion on the surface of the ball 8 can be reduced, the reliability of the torque limiter operation can be improved.
[0035]
(Sixth embodiment)
12 and 13 show a sixth embodiment. In each of the above-described embodiments, an annular groove 6d is formed on the hub 6 side, and a disc spring 9 is disposed in the annular groove 6d. However, in the sixth embodiment, the annular groove 1f is formed in the side plate portion 1c of the pulley 1, and the disc spring 9 is positioned by the circlip 10 in the annular groove 1f on the pulley 1 side. The side plate portion 1c is provided with a cylindrical ball holding hole 1g (corresponding to the above-described cylindrical second ball holding hole 6c). Moreover, the same taper surface 13 as 3rd Embodiment is provided in the outer peripheral part of the annular groove 1f.
[0036]
On the other hand, the side plate portion 6b of the hub 6 is provided with a conical ball holding hole 6e (corresponding to the above-mentioned conical first ball holding hole 1d) and a cylindrical hole 6f (corresponding to the above-mentioned cylindrical hole 1e). ing.
According to the sixth embodiment, when an overload occurs when the compressor is locked or the like, the ball 8 falls into the annular groove 1f of the pulley 1 due to the reversal of the disc spring 9, and the power transmission from the pulley 1 to the hub 6 is interrupted. The After the power transmission is interrupted, the ball 8 is held on the side of the pulley 1 that is in a rotating state, so that the ball 8 adheres to the outer peripheral portion in the annular groove 1f by centrifugal force. Since the ball 8 moves in the direction away from the hub 6 along the tapered surface 13 of the outer peripheral portion in the annular groove 1f, the outer peripheral tip of the disc spring 9 and the tapered surface 13 are moved in the same manner as in the third embodiment. The ball 8 can be sandwiched between the two. Thereby, rattling of the ball 8 can be reliably prevented.
[0037]
(Other embodiments)
In each of the above embodiments, the disc spring 9 is used as an elastic member having a reversing action. However, the elastic member is not limited to the disc spring 9 and any elastic member having a reversing action can be used. .
The present invention is not limited to a power transmission device to a compressor of an automotive air conditioner, and can be widely applied to various uses.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention, and shows a state during normal operation.
FIG. 2 is a front view of FIG. 1;
FIG. 3 is an enlarged cross-sectional view of a main part of FIG.
FIG. 4 is an explanatory diagram for explaining the progress of the torque limiter operation during an overload operation in the first embodiment.
FIG. 5 is a characteristic diagram of a disc spring used in the first embodiment.
FIG. 6 is a longitudinal sectional view showing a power cut-off state after operation of a torque limiter during overload operation in the first embodiment.
FIG. 7 is a longitudinal sectional view showing a second embodiment of the present invention, and shows a state during normal operation.
FIG. 8 is a longitudinal sectional view showing a third embodiment of the present invention, and shows a power cut-off state after the torque limiter is operated.
FIG. 9 is a longitudinal sectional view showing a fourth embodiment of the present invention, and shows a power cut-off state after a torque limiter is actuated.
FIG. 10 is a longitudinal sectional view showing a fifth embodiment of the present invention, and shows a state during normal operation.
FIG. 11 is a front view of a holding plate used in the fifth embodiment.
FIG. 12 is a longitudinal sectional view showing a sixth embodiment of the present invention, and shows a state during normal operation.
13 is a front view of FIG. 12. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Pulley (drive side rotation member), 1c ... Side plate part,
1d, 6e ... first conical ball holding hole, 3 ... compressor,
5 ... rotating shaft, 6 ... hub (driven side rotating member), 6b ... side plate,
6c, 1g ... cylindrical second ball holding hole, 6d, 1f ... concave groove, 8 ... ball,
9: Disc spring (elastic means).

Claims

The drive side rotation member (1, 11, 12) that rotates by receiving the rotational force from the rotation drive source includes a drive side plate portion (1c, 11a) extending in the radial direction, and
The driven side rotating member (6) connected to the rotating shaft (5) of the driven side device (3) includes a driven side plate portion (6b) extending in the radial direction,
A plurality of conical first ball holding holes ( 1d ) are provided in the circumferential direction of the driving side plate (1c, 11a),
In the circumferential direction of the driven side plate portion (6b), a plurality of second ball holding holes ( 6c ) are provided corresponding to the plurality of first ball holding holes ( 1d ),
And a plurality of balls (8) capable of contacting the inclined wall surface of the first ball holding hole ( 1d ) in a state of being fitted and locked to the second ball holding hole ( 6c ),
A concave groove (6d) is formed on the back side of the second ball holding hole (6c) in the driven side plate portion (6b),
In the concave groove (6d), a disc spring (9) that is in direct contact with the plurality of balls (8) and whose shape is reversed when a predetermined load is applied is disposed,
During normal operation of the driven device (3), a spring force is applied to the plurality of balls (8) by the disc spring (9) to cause the plurality of balls (8) to move to the first ball holding holes ( 1d). ) Is pressed against the inclined wall surface with a predetermined load, power is transmitted from the driving side rotating member (1, 11, 12) to the driven side rotating member (6) through the fitting portions of the plurality of balls (8). Communicated,
On the other hand, when the driven device (3) is overloaded, the axial load applied to the ball (8) from the inclined wall surface of the first ball holding hole ( 1d ) exceeds the predetermined load of the disc spring (9). Accordingly, the shape of the disc spring (9) is inverted in a direction away from said ball (8), said leaves the inclined wall surface of the ball (8) is the first ball holding hole (1d), and this withdrawal the The ball (8) moves into the concave groove (6d), so that power transmission from the driving side rotating member (1, 11, 12) to the driven side rotating member (6) is cut off. A power transmission device characterized by that.

The drive side rotation member (1, 11, 12) that rotates by receiving the rotational force from the rotation drive source includes a drive side plate portion (1c, 11a) extending in the radial direction, and
The driven side rotating member (6) connected to the rotating shaft (5) of the driven side device (3) includes a driven side plate portion (6b) extending in the radial direction,
A plurality of conical first ball holding holes ( 6e ) are provided in the circumferential direction of the driven side plate portion (6 b),
In the circumferential direction of the drive side plate (1c, 11a), a plurality of second ball holding holes ( 1g ) are provided corresponding to the plurality of first ball holding holes ( 6e ),
And a plurality of balls (8) capable of contacting the inclined wall surface of the first ball holding hole ( 6e ) in a state of being fitted and locked to the second ball holding hole ( 1g ),
A concave groove (1f) is formed on the back side of the second ball holding hole (1g) in the driving side plate portion (1c, 11a),
In the concave groove (1f), a disc spring (9) that is in direct contact with the plurality of balls (8) and whose shape is reversed when a predetermined load is applied is disposed,
During normal operation of the driven device (3), a spring force is applied to the plurality of balls (8) by the disc spring (9) to cause the plurality of balls (8) to move to the first ball holding holes ( 6e). ) Is pressed against the inclined wall surface with a predetermined load, power is transmitted from the driving side rotating member (1, 11, 12) to the driven side rotating member (6) through the fitting portions of the plurality of balls (8). Communicated,
On the other hand, when the driven device (3) is overloaded, the axial load applied to the ball (8) from the inclined wall surface of the first ball holding hole ( 6e ) exceeds the predetermined load of the disc spring (9). Accordingly, the shape of the disc spring (9) is inverted in a direction away from said ball (8), said leaves the inclined wall surface of the ball (8) is the first ball holding hole (6e), and this withdrawal the ball Lumpur (8) is moved into said groove (1f), thereby, the power transmission is blocked from said driving side rotational member (1, 11, 12) wherein the driven side rotational member (6) A power transmission device characterized by that.

The drive-side rotation member includes a pulley (1) that is rotated by a rotational force transmitted from a rotation drive source via a belt, and a cylindrical rotor disposed at an interval on the inner peripheral side of the pulley (1). The power transmission according to claim 1 or 2 , comprising: (11) and an elastically deformable rubber member (12) integrally connecting the pulley (1) and the rotor (11). apparatus.