JP3587427B2

JP3587427B2 - One-way clutch

Info

Publication number: JP3587427B2
Application number: JP22972497A
Authority: JP
Inventors: 博文宮田
Original assignee: Bando Chemical Industries Ltd
Current assignee: Bando Chemical Industries Ltd
Priority date: 1997-08-26
Filing date: 1997-08-26
Publication date: 2004-11-10
Anticipated expiration: 2017-08-26
Also published as: JPH1163024A

Description

【０００１】
【発明の属する技術分野】
本発明は、構造が簡単でかつ高精度を要しない低コストの一方向クラッチに関し、特に過度の入力トルクへの対策に関する。
【０００２】
【従来の技術】
一般に、自動車や農業機器、ＯＡ機器等に使用する一方向クラッチとしては、ローラ式のものやスプラグ式のもの等がよく知られている。
【０００３】
従来の一方向クラッチの一例として、ローラ式の一方向クラッチについて説明すると、図８に模式的に示すように、インナレースａと、このインナレースａに相対回転可能に組み付けられたアウタレースｂと、このアウタレースｂの内周に周方向に所定ピッチ間隔をおいて設けられた複数（同図には１つだけ示している）の凹部ｃ，ｃ，…と、それら各凹部ｃ内にそれぞれ配置されたローラｄと、これら各ローラｄをインナレースａの外周面ｅとアウタレースｂの内周面ｆとの間に挟み込まれる方向（図示する例では反時計回り方向）に向かって押圧付勢する図外のスプリングとを備えている。
【０００４】
そして、例えば上記インナレースａにスプリングの付勢方向と同じ方向（同図の反時計回り方向）のトルクが入力されたときには、各ローラｄはインナレースａの外周面ｅとアウタレースｂの内周面ｆとの間に挟み込まれ、楔作用を営んで両者ａ，ｂをロックさせるので、インナレースａに入力されたトルクはアウタレースｂに伝達される。一方、上記付勢方向とは逆の方向（同図の時計回り方向）のトルクが入力されたときには、各ローラｄは両レースａ，ｂ間に挟み込まれず、インナレースａはアウタレースｂからフリーの状態で回転する。つまり、このときには、インナレースａのトルクはアウタレースｂに伝達されない。
【０００５】
【発明が解決しようとする課題】
しかしながら、上記従来の一方向クラッチでは、非常に高精度の部品が必要であり、また構造も複雑であることから、低コストで得ることは困難であるという問題がある。
【０００６】
加えて、上記一方向クラッチの最大伝達トルクを超えるトルクが入力されて該クラッチが破損した場合には、部品の交換だけでは済まず、クラッチ自体を交換しなければならないという問題もある。したがって、そのような事態に対処するためには、別途、トルクリミッタを付設しなければならず、さらにコストがかさむことになる。
【０００７】
また、上記最大伝達トルクを超えないまでも過大なトルクが入力された場合には、そのトルクがそのまま出力されることになるという問題もある。よって、そのような事態を防止する上でもトルクリミッタが必要となる。
【０００８】
本発明は斯かる諸点に鑑みてなされたものであり、その主な目的は、２軸間に巻き掛けたベルトに初張力が付与されているときには両軸間のトルク伝達を行う一方、初張力が付与されていないときにはトルク伝達を行わないベルト伝動機構の原理を応用することで、構造が簡単でありかつ高精度が要求されなくて低コストであるとともに、過大な入力トルクに対し出力トルクを抑えることのできる一方向クラッチが得られるようにすることにある。
【０００９】
【課題を解決するための手段】
上記の目的を達成するために、本発明では、２軸ベルト伝動機構において、一方の軸に、両軸の相対回転方向に応じてベルト初張力を増減させるように揺動する揺動部を設けることで、一方向クラッチとしての機能を発揮させることができるようにした。また、その際に、入力トルクの増加に応じてベルトの滑り発生率が上昇することに着目し、上記滑りをコントロールできるようにすることで、過度の入力トルクに対し、ベルトの破断により出力トルクを抑えることができるようにした。
【００１０】
具体的には、請求項１の発明では、外周に断面円形状の摩擦面が形成された第１の回転部材と、外周に上記第１回転部材の摩擦面の半径方向外方に位置する断面円弧状の摩擦面が形成されているとともに該摩擦面の周方向一端側に偏った位置において第１回転部材の摩擦面の中心軸線と平行な軸心回りに揺動可能に枢支された揺動部を有していて、該第１の回転部材に上記中心軸線回りに相対回転可能に組み付けられた第２の回転部材と、これら第１及び第２回転部材の両摩擦面間に巻き掛けられた無端の摩擦部材と、上記両回転部材が一方向（以下、ロック方向という）に相対回転するときには上記摩擦部材が揺動部をその摩擦面の周方向他端側が半径方向外方に変位して該摩擦部材の初張力を増加させる方向に回動させ、上記両回転部材が他方向（以下、フリー方向という）に相対回転するときには上記摩擦部材が揺動部をその摩擦面の周方向他端側が半径方向内方に変位して該摩擦部材の初張力を減少させる方向に回動させるようにそれぞれ上記摩擦部材に初張力を付与する初張力付与機構とを備えるようにする。そして、上記第１回転部材の摩擦面と上記摩擦部材との間の摩擦係数及び接触角度をそれぞれμ１′及びθ１とし、かつ上記第２回転部材の摩擦面と上記摩擦部材との間の摩擦係数及び接触角度をそれぞれμ２′及びθ２としたときに、上記揺動部における摩擦面の周方向一端側の揺動アーム長さＬ２に対する該摩擦面の周方向他端側の揺動アーム長さＬ１の比Ｌ１／Ｌ２（以下、揺動アーム比という）が、
Ｌ１／Ｌ２≦ｅμ^１′・θ^１
Ｌ１／Ｌ２≦ｅμ^２′・θ^２
の２つの関係式を共に満たすように設定されているものとする。
【００１１】
上記の構成において、第１及び第２の回転部材の一方にトルクが入力されて該両回転部材が何れかの方向に相対回転するとき、その回転方向に応じて第１及び第２の回転部材間におけるトルク伝達の断接が行われる。
【００１２】
すなわち、上記の両回転部材がロック方向に相対回転するときには、初張力付与機構によって初張力の付与されている摩擦部材により、揺動部はその摩擦面の周方向他端側が半径方向外方に変位して上記摩擦部材の初張力を増加させる方向に回動する。よって、このときには、第１及び第２の回転部材の各摩擦面と摩擦部材との間のグリップ力が共に増加するので、該第１及び第２の回転部材間においてトルクは摩擦部材を介して伝達される。
【００１３】
一方、上記両回転部材がフリー方向に相対回転するときには、揺動部はその摩擦面の周方向他端側が半径方向内方に変位して摩擦部材の初張力を減少させる方向に回動する。よって、第１及び第２の回転部材の各摩擦面と摩擦部材との間のグリップ力が失われるので、このときには、第１及び第２の回転部材間でのトルク伝達は行われない。
【００１４】
さらに、上記両回転部材がロック方向に相対回転してトルク伝達がなされるときに上記入力トルクが増加すると、それに応じて摩擦部材の張側張力及び緩み側張力が増加するので、両回転部材間の最大伝達トルク及び摩擦部材の滑り発生率は共に上昇する。その際に、上記滑り発生率は、摩擦部材の張側張力ｔ１と緩み側張力ｔ２との比ｔ１／ｔ２が、該摩擦部材と各摩擦面との間の摩擦係数にその接触角度〔単位：ラジアン〕を乗算した値が自然対数の底に累乗されてなる値に近付くにつれて急激に上昇するようになり、その値を超えると発生率が１００％となる状態に移行しようとする。
【００１５】
このとき、上記摩擦部材の張側張力ｔ１がその許容張力の範囲内であるときに上記滑り発生率が１００％に達する場合には、摩擦部材の滑りが発生することになるので、入力トルクがさらに上昇しても略一定のトルクのみが摩擦部材の滑りを伴いつつ両回転部材間で伝達される。つまり、この場合には、過度の入力トルクに対し略一定のトルクのみが出力される。
【００１６】
上記の場合とは逆に、上記張側張力ｔ１が許容張力の範囲内であるときに上記滑り発生率が１００％に達しない場合には、摩擦部材が破断して両回転部材間でのトルク伝達は停止される。つまり、この場合には、過度の入力トルクに対しトルクの出力自体が停止する。尚、摩擦部材の破断した一方向クラッチは該摩擦部材の交換により再使用可能であり、また摩擦部材の交換自体は比較的に容易である。
【００１７】
次に、上記摩擦部材の滑りの発生について詳しく説明する。例えば、第１の回転部材の摩擦面との間で摩擦部材の滑りが発生するときの該摩擦部材の張側張力Ｔ１及び緩み側張力Ｔ２の比Ｔ１／Ｔ２と、第１の回転部材の摩擦面と摩擦部材との間の摩擦係数μ１′及び接触角度θ１との間には、先にも述べたように、
Ｔ１／Ｔ２＞ｅμ^１′・θ^１
という関係式（但し，ｅは自然定数の底）が成立することは知られている。つまり、摩擦部材の張側張力ｔ１と緩み側張力ｔ２との比ｔ１／ｔ２がＴ１／Ｔ２以上（ｔ１／ｔ２≧Ｔ１／Ｔ２）となる場合には摩擦部材の滑りが発生し、逆にＴ１／Ｔ２よりも小さい（ｔ１／ｔ２＜Ｔ１／Ｔ２）場合には摩擦部材の滑りは発生せず、したがって摩擦部材が破断することになる。
【００１８】
ここで、上記揺動部の周方向一端側に作用するモーメントと、周方向他端側に作用するモーメントとが互いに釣り合っているときに、周方向一端側の揺動アーム長さＬ２及び摩擦部材の張側張力ｔ１と、周方向他端側の揺動アーム長さＬ１及び摩擦部材の緩み側張力ｔ２との間には、Ｌ２・ｔ１＝Ｌ１・ｔ２の関係があるので、ｔ１／ｔ２＝Ｌ１／Ｌ２が成立する。
【００１９】
したがって、上記第１及び第２の回転部材がロック方向に相対回転して入力トルクが増加するときに、揺動部の揺動アーム比Ｌ１／Ｌ２が、第１回転部材の摩擦面と摩擦部材との間の摩擦係数μ１′にその接触角度θ１を乗算した値μ１′・θ１だけ自然対数の底ｅが累乗されてなる値ｅμ^１′・θ^１以下（Ｌ１／Ｌ２≦ｅμ^１′・θ^１）であるので、上記摩擦部材の張力比ｔ１／ｔ２は滑り発生時の張力比Ｔ１／Ｔ２よりも小さく（ｔ１／ｔ２＝Ｌ１／Ｌ２≦ｅμ^１′・θ^１＜Ｔ１／Ｔ２）抑えられることになる。よって、摩擦部材の滑り率は１００％に達せず、摩擦部材と第１の回転部材の摩擦面との間に滑りは発生しない。
【００２０】
また、上記揺動アーム比Ｌ１／Ｌ２は、第２回転部材の摩擦面と摩擦部材との間の摩擦係数μ２′にその接触角度θ２を乗算した値μ２′・θ２だけ自然対数の底ｅが累乗されてなる値ｅμ^２′・θ^２以下（Ｌ１／Ｌ２ ≦ｅμ^２′・θ^２）であるので、上記の場合と同様に、上記摩擦部材の張力比ｔ１／ｔ２が、第２回転部材の摩擦面との間に摩擦部材の滑りの発生するときの張力比Ｔ１／Ｔ２よりも小さく（ｔ１／ｔ２＝Ｌ１／Ｌ２ ≦ｅμ^２′・θ^２＜Ｔ１／Ｔ２）抑えられるので、摩擦部材と第２の回転部材の揺動部の摩擦面との間においても滑りは発生しない。
【００２１】
つまり、この発明の場合には、上記入力トルクの増加に応じて第１及び第２の回転部材間の最大伝達トルクのみが上昇を続け、該最大伝達トルクが摩擦部材の許容張力を超えた時点で摩擦部材が破断する。
【００２２】
請求項２の発明では、外周に断面円形状の摩擦面が形成された第１の回転部材と、この第１回転部材の摩擦面の半径方向外方に互いに周方向にずれた２つの止着部が設けられているとともに該２つの止着部のうちの一方の止着部の側に偏った位置において上記第１回転部材の摩擦面の中心軸線と平行な軸心回りに揺動可能に枢支された揺動部を有していて、該第１の回転部材に上記中心軸線回りに相対回転可能に組み付けられた第２の回転部材と、上記第１の回転部材の摩擦面に巻き掛けられているとともに、両端がそれぞれ上記第２の回転部材の揺動部の対応する止着部に止着された有端の摩擦部材と、上記両回転部材がロック方向に相対回転するときには上記摩擦部材が揺動部を上記他方の止着部が半径方向外方に変位して該摩擦部材の初張力を増加させる方向に回動させ、上記両回転部材がフリー方向に相対回転するときには上記摩擦部材が揺動部を上記他方の止着部が半径方向内方に変位して該摩擦部材の初張力を減少させる方向に回動させるようにそれぞれ上記摩擦部材に初張力を付与する初張力付与機構とを備えるようにする。
そして、上記第１の回転部材の摩擦面と摩擦部材との間の摩擦係数及び接触角度をそれぞれμ１′及びθ１としたときに、上記揺動部における一方の止着部の側の揺動アーム長さＬ２に対する他方の止着部の側の揺動アーム長さＬ１の比Ｌ１／Ｌ２が、
Ｌ１／Ｌ２≦ｅμ^１′・θ^１
の関係式を満たすように設定されているものとする。
【００２３】
上記の構成において、摩擦部材は、上記請求項１及び２の発明の場合とは異なって有端であり、その両端がそれぞれ第２の回転部材の揺動部の対応する止着部に止着されているので、該第２の回転部材と一体となって回転する。したがって、第１及び第２回転部材間のトルク伝達の断接は、摩擦部材と第１の回転部材の摩擦面との間のみにおいて行われる。
【００２４】
そして、上記第１及び第２の回転部材がロック方向に相対回転して入力トルクが増加するとき、上記揺動部における一方の止着部の側の揺動アーム長さＬ２に対する該揺動部における他方の止着部の側の揺動アーム長さＬ１の比Ｌ１／Ｌ２が、上記第１の回転部材の摩擦面と摩擦部材との間の摩擦係数μ１′にその接触角度θ１を乗算した値μ１′・θ１だけ自然対数の底ｅが累乗されてなる値ｅμ^１′・θ^１以下（Ｌ１／Ｌ２≦ｅμ^１′・θ^１）であることから、上記請求項１の発明の場合と同様に、上記摩擦部材の張力比ｔ１／ｔ２が滑り発生時の摩擦部材の張力比Ｔ１／Ｔ２よりも小さく（ｔ１／ｔ２＝Ｌ１／Ｌ２≦ｅμ^１′・θ^１＜Ｔ１／Ｔ２）抑えられるので、摩擦部材の滑り率は１００％に達せず、摩擦部材と第１の回転部材の摩擦面との間に滑りは発生しない。よって、この発明の場合には、請求項２の発明の場合と同じく、上記入力トルクの増加に応じて第１及び第２の回転部材間の最大伝達トルクのみが摩擦部材の破断まで上昇を続ける。
【００２５】
【発明の実施の形態】
以下、本発明の実施形態を図面に基づいて説明する。
【００２６】
（実施形態１）
図２及び図３は、本発明の実施形態１に係る一方向クラッチを示しており、この一方向クラッチは、例えば動力取出装置（ＰＴＯ）を備えた車両ではその動力取出装置の出力端に配置して用いられる他、農業機器としてのコンバインでは刈取り機構部の入力端に、また田植機では植付け機構部の入力端にそれぞれ配置して用いられる。
【００２７】
上記一方向クラッチは、外周に断面円形状の摩擦面１ａが形成された第１の回転部材１と、外周に第１回転部材１の摩擦面１ａの半径方向外方に位置する断面円弧状の摩擦面２ａが形成されているとともに該摩擦面２ａの周方向一端側（図２の左端側）に偏った位置において第１回転部材１の摩擦面１ａの中心軸線Ｐと平行な軸心Ｑの回りに揺動可能な揺動部３を有していて、第１回転部材１に中心軸線Ｐの回りに相対回転可能に組み付けられた第２の回転部材２と、これら第１及び第２回転部材１，２の両摩擦面１ａ，摩擦面２ａ間に巻き掛けられていて、初張力が付与された状態で両回転部材１，２の相対回転に伴って揺動部３を揺動させかつ該揺動により上記初張力が増減する無端の摩擦部材としてのゴム製の平ベルト４と、この平ベルト４に上記初張力を付与する初張力付与機構としての板ばね５とを備えている。
【００２８】
具体的に説明すると、上記第１の回転部材１は、平プーリからなっており、そのボス部１ｂは図３の左方向に向かって突出するように延設されている。また、ボス部１ｂの内周には、該ボス部１ｂに連結される図外のシャフトとキー結合するためのキー溝６が中心軸線Ｐに沿って設けられている。
【００２９】
一方、上記第２の回転部材２は、ボス部７ａにおいてベアリング８を介し上記第１回転部材１のボス部１ｂに相対回転可能に組み付けられたカップ状の本体７と、この本体７の開口を覆うように該本体７に複数本のボルト９，９，…により取り付けられた円板状のカバー部材１０とを有する。ベアリング８は、図３に示すように、平ベルト４と同一面内に配置されており、このことで、該ベアリング８に平ベルト４の張力によるモーメントが作用しないようになっている。また、カバー部材１０の中央には、第１回転部材１のボス部１ｂに対応する円形の開口１０ａが設けられている。
【００３０】
上記揺動部３は、内外周が共に断面円弧状である円弧形状をなしていて、第２回転部材２の本体７及びカバー部材１０において両端部が支承された枢支ピン１１により揺動軸心Ｑの回りに揺動可能に支持されている。揺動部３の摩擦面２ａの周方向両端部は、それ以外の部分よりも小さい曲率の断面円弧状に形成されていて、該両端部における平ベルト４の屈曲を回避するとともに、摩擦面２ａに対する平ベルト４の導入及び導出が円滑に行われるようにされている。
【００３１】
また、上記揺動部３は、その摩擦面２ａにおける揺動軸心Ｑの周方向一端側（図２の左端側）の揺動アーム長さＬ２が、該摩擦面２ａにおける揺動軸心Ｑの周方向他端側（同図の右端側）の揺動アーム長さＬ１に比べて小さく（Ｌ２＜Ｌ１）設定されている。詳しく説明すると、摩擦面２ａの周方向両端を結ぶ線分の中点に対し、揺動軸心Ｑは該線分の延びる方向において摩擦面２ａの周方向一端の側に偏って配置されている。そして、揺動部３の摩擦面２ａの周方向両端を通る直線の方向（同図の左右方向）における揺動軸心Ｑと揺動部３の摩擦面２ａの周方向一端部との間の距離が上記一端側の揺動アーム長さＬ２であり、同直線方向における揺動軸心Ｑと揺動部３の摩擦面２ａの周方向他端部との間の距離が上記他端側の揺動アーム長さＬ１である。
【００３２】
よって、上記揺動部３は、第１及び第２の回転部材１，２がロック方向に相対回転するとき、例えば第１の回転部材１が同図の反時計回り方向に回転するときには、同図に仮想線で示すように、摩擦面２ａの周方向他端側が半径方向外方に変位する方向、つまり平ベルト４を押圧する方向に回動して該平ベルト４の初張力を増加させ、一方、第１及び第２の回転部材１，２がフリー方向に相対回転するとき、例えば第１の回転部材１が同図の時計回り方向に回転するときには、摩擦面２ａの周方向他端側が半径方向内方に変位する方向、つまり平ベルト４を押圧する方向とは逆の方向に回動して該平ベルト４の初張力を減少させるようになっている。
【００３３】
上記板ばね５は、図２に仮想線で示すように、揺動部３を該揺動部３の摩擦面２ａの周方向他端側（同図の右端側）が平ベルト４を押圧する方向（同図の時計回り方向）に向かって常に回動付勢するように配置されている。この板ばね５は、その基端において第２回転部材２の本体７の内周面にボルト１２により固定されていて、その先端側により揺動部３の揺動軸方向一側又は両側を押圧するようになされている。
【００３４】
さらに、上記第２回転部材２の本体７には、図４に示すように、該第２回転部材２の入出力用ホイールとしてのＶプーリ１３が脱着可能に取り付けられている。すなわち、本体７の周方向の複数箇所には、Ｖプーリ１３の挿通孔１３ａ，１３ａ，…に挿通された取付ボルト１４，１４，…の先端を螺着するためのボルト孔７ａ，７ａ，…が予め設けられている。また、第１回転部材１のボス部１ｂの外周にはＣリング１５を嵌着するための係止溝１６が周設されており、これらのことで、Ｖプーリ１３と第１回転部材１のボス部１ｂとの間に介装されるベアリング１７を係止するようになされている。
【００３５】
そして、本実施形態では、上記揺動部３における摩擦面２ａの周方向一端側の揺動アーム長さＬ２に対する該摩擦面２ａの周方向他端側の揺動アーム長さＬ１の比Ｌ１／Ｌ２（揺動アーム比）が、第１回転部材１の摩擦面１ａと平ベルト４との間の摩擦係数μ１′にその接触角度θ１を乗算した値μ１′・θ１だけ自然対数の底ｅが累乗されてなる値ｅμ^１′・θ^１と、第２回転部材２の摩擦面２ａと平ベルト４との間の摩擦係数μ２′にその接触角度θ２を乗算した値μ２′・θ２だけ自然対数の底ｅが累乗されてなる値ｅμ^２′・θ^２とに基づいて設定されている。
【００３６】
すなわち、本一方向クラッチへの入力トルクの大きさに拘わらず平ベルト４と第１及び第２の回転部材１，２の各摩擦面１ａ，２ａとの間において滑りを発生させないようにする場合には、上記揺動アーム比Ｌ１／Ｌ２は、
Ｌ１／Ｌ２≦ｅμ^１′・θ^１・・・▲１▼
Ｌ１／Ｌ２≦ｅμ^２′・θ^２・・・▲２▼
の２つの関係式▲１▼及び▲２▼を共に満たすように設定される。
【００３７】
一方、本一方向クラッチへの入力トルクの増加に伴い、平ベルト４と第１及び第２の回転部材１の摩擦面１ａ，２ａの少なくとも一方との間において滑りを発生させるようにする場合には、上記揺動アーム比Ｌ１／Ｌ２は、
Ｌ１／Ｌ２＞ｅμ^１′・θ^１・・・▲３▼
Ｌ１／Ｌ２＞ｅμ^２′・θ^２・・・▲４▼
の２つの関係式▲３▼及び▲４▼のうちの少なくとも一方を満たすように設定される。
【００３８】
ここで、上記のように構成された一方向クラッチの作動について、第１の回転部材１にトルクが入力される場合を例にとって説明する。
【００３９】
上記第１の回転部材１がフリー方向（図２の時計回り方向）に回転するときには、揺動部３が平ベルト４の初張力を減少させる方向（同時計回り方向）に回動するので、第１及び第２の回転部材１，２間でのトルク伝達は行われない。
【００４０】
一方、上記第１の回転部材１がロック方向（図２の反時計回り方向）に回転するときには、揺動部３が平ベルト４の初張力を増加させる方向（同反時計回り方向）に回動するので、第１及び第２の回転部材１，２間でのトルク伝達が行われる。そして、上記入力トルクが増加すると、それに応じて平ベルト４の滑り発生率及び最大伝達トルクは共に上昇する。
【００４１】
このとき、上記揺動アーム比Ｌ１／Ｌ２が関係式▲１▼及び▲２▼を共に満たすように設定されている場合には、「課題を解決するための手段」の項で詳しく説明したように、平ベルト４の張側張力ｔ１（この場合には図２の左側スパンの張力）及び緩み側張力ｔ２（この場合には同図の右側スパンの張力）の比ｔ１／ｔ２が、第１の回転部材１の摩擦面１ａとの間に滑りの発生するときの平ベルト４の張側張力Ｔ１及び緩み側張力Ｔ２の比Ｔ１／Ｔ２よりも小さく（ｔ１／ｔ２＜Ｔ１／Ｔ２）抑えられるので、第１の回転部材１の摩擦面１ａと平ベルト４との間に滑りは発生しない。また、平ベルト４の張力比ｔ１／ｔ２は、第１の回転部材１の摩擦面１ａとの間に滑りの発生するときの該平ベルト４の張力比Ｔ１／Ｔ２よりも小さく（ｔ１／ｔ２＜Ｔ１／Ｔ２）抑えられるので、第１の回転部材１の摩擦面１ａと平ベルト４との間に滑りは発生しない。よって、この場合には、上記入力トルクに応じて第１及び第２の回転部材１，２間の最大伝達トルクのみが平ベルト４の破断まで上昇を続け、過度の入力トルクに対しては平ベルト４の破断によりトルクの出力自体が停止される。そして、平ベルト４が破断したときには、該平ベルト４の交換により一方向クラッチは再使用できるようになる。
【００４２】
一方、上記揺動アーム比Ｌ１／Ｌ２が関係式▲３▼及び▲４▼のうちの少なくとも一方を満たすように設定されている場合には、上記の場合とは逆に平ベルト４の張力比ｔ１／ｔ２が滑り発生時の張力比Ｔ１／Ｔ２に達する（ｔ１／ｔ２≧Ｔ１／Ｔ２）ようになるので、平ベルト４と第１回転部材１の摩擦面１ａとの間及び平ベルト４と第２回転部材２の摩擦面２ａとの間のうちの少なくとも一方において、つまり、関係式▲３▼を満たしている場合には第１回転部材１の摩擦面１ａとの間において、また関係式▲４▼を満たしている場合には第２回転部材２の摩擦面２ａとの間においてそれぞれ滑りが発生する。そして、滑り発生以降は、上記入力トルクが増加しても、略一定のトルクのみが両回転部材１，２間で伝達されるようになる。よって、この場合には、過度の入力トルクに対しては平ベルト４の滑りにより略一定のトルクのみが出力されるようになる。
【００４３】
したがって、本実施形態に係る一方向クラッチによれば、第１の回転部材１に形成された断面円形状の摩擦面１ａと、第２回転部材２の有する揺動部３に形成された断面円弧状の摩擦面２ａとの間に無端の平ベルト４を巻き掛け、両回転部材１，２の相対回転に伴って平ベルト４により揺動部３を揺動させ、その揺動部３の揺動により平ベルト４の初張力を増減させることで両回転部材１，２間でのトルク伝達の断接を行うようにしたので、構造が簡単でありかつ高精度が要求されなくて低コストであるとともに、過大な入力トルクに対しては平ベルト４の滑りにより略一定のトルクのみを出力させたり又は平ベルト４の破損により出力自体を停止させたりすることで出力トルクを抑えることができる。
【００４４】
さらに、上記揺動部３の揺動アーム比Ｌ１／Ｌ２を、第１回転部材１の摩擦面１ａと平ベルト４との間の摩擦係数μ１′にその接触角度θ１を乗算した値μ１′・θ１だけ自然対数の底ｅが累乗されてなる値ｅμ^１′・θ^１と、第２回転部材２の揺動部３の摩擦面２ａと平ベルト４との間の摩擦係数μ２′にその接触角度θ２を乗算した値μ２′・θ２だけ自然対数の底ｅが累乗されてなる値ｅμ^２′・θ^２とに基づいて設定し、このことで平ベルト４の滑りをコントロールするようにしたので、例えば滑り発生時の平ベルト４と各摩擦面１ａ，２ａとの間の関係式（Ｔ１／Ｔ２＞ｅμ^１′・θ^１，ｅμ^２′・θ^２）に基づく平ベルト４の張力比ｔ１／ｔ２や摩擦係数μ１′，μ２′及び接触角度θ１，θ２の設定によって行うようにする場合よりも容易に滑りをコントロールすることができる。
【００４５】
尚、上記実施形態では、摩擦部材としてゴム製の平ベルト４を用いるようにしているが、その材質や形状は特に限定されるものではなく、例えば金属フープなどを用いるようにしてもよい。
【００４６】
−具体例−
次に、図１に模式的に示す上記の一方向クラッチにおいて、第１の回転部材１にロック方向（同図の時計回り方向）のトルクが入力されて該回転部材１の摩擦面１ａと平ベルト４との間に滑りが発生するとき、そのときの平ベルト４における張側張力Ｔ１及び緩み側張力Ｔ２間の比Ｔ１／Ｔ２と、摩擦面１ａ及びベルト４間の摩擦係数μ１′及び接触角度θ１〔単位：ラジアン〕との間には、
Ｔ１／Ｔ２＞ｅμ^１′・θ^１
という関係式が成立するということを前提にして、滑り発生時の揺動部３の揺動アーム比Ｌ１／Ｌ２は、同じく滑り発生時の張力比Ｔ１／Ｔ２に等しく、その結果、
Ｌ１／Ｌ２＞ｅμ^１′・θ^１
という関係式が成立するということを説明する。尚、本例では、第１回転部材１の摩擦面１ａの半径ＲをＲ＝４０．５０ｍｍに、該摩擦面１ａと平ベルト４との間の接触角度θ１をθ１＝πに、揺動部３の摩擦面２ａの周方向一端側（図１の左端側）の揺動アーム長さＬ２をＬ２＝２５．３０ｍｍに、周方向他端側（同図の右端側）の揺動アーム長さＬ１をＬ１＝５５．７０ｍｍに、そして、摩擦面２ａの周方向両端を通る直線方向（同図の左右方向）と直交する方向（同図の上下方向）における揺動軸心Ｑの中心軸線Ｐからの偏心量を２７．００ｍｍにそれぞれ設定している。
【００４７】
先ず、上記滑り発生時の平ベルト４の張側張力Ｔ１及び緩み側張力Ｔ２は、それぞれ、
Ｔ１＝有効張力×ｅμ^１′・θ^１／（ｅμ^１′・θ^１−１）
Ｔ２＝有効張力／（ｅμ^１′・θ^１−１）
と表わされる。
【００４８】
ここで、上記第１の回転部材１に５ｋｇｆ−ｍのトルクが入力されたときに上記滑りが発生するとして、そのときの平ベルト４の有効張力は、
５〔ｋｇｆ−ｍ〕÷０．０４０５〔ｍ〕＝１２３．４５６〔ｋｇｆ〕
である。
【００４９】
また、上記揺動部３の揺動アーム比Ｌ１／Ｌ２が、
Ｌ１／Ｌ２＝５５．７ｍｍ／２５．３ｍｍ＝２．２０１５であるので、μ１′・θ１は、

であり、したがって、ｅμ^１′・θ^１は、
ｅμ^１′・θ^１＝ｅ^{０．７８９}＝２．２．．．
である。
【００５０】
これらから、上記平ベルト４の張側張力Ｔ１及び緩み側張力Ｔ２をそれぞれ求めると、

であり、よって、上記揺動部３の揺動軸心Ｑに加わる軸荷重は、
Ｔ１＋Ｔ２＝２２６．２１８＋１０２．７６２＝３２８．９８〔ｋｇｆ〕
となる。
【００５１】
次に、上記軸荷重を第１回転部材１に対するトルクに変換すると、このときの揺動軸心Ｑの中心軸線Ｐからの偏心量（（Ｌ１−Ｌ２）／２）が、

であるので、上記トルクは、
３２８．９８×０．０１５２＝５．０００．．．〔ｋｇｆ−ｍ〕
となる。
【００５２】
よって、上記第１の回転部材１の摩擦面１ａと平ベルト４との間に滑りが発生するとき、揺動部３の揺動アーム比Ｌ１／Ｌ２は、平ベルト４の滑り発生時の張力比Ｔ１／Ｔ２に等しく、その結果、
Ｌ１／Ｌ２＞ｅμ^１′・θ^１
という関係式の成立することが判る。
【００５３】
（実施形態２）
図５は、本発明の実施形態２に係る一方向クラッチの要部を示しており、この一方向クラッチの全体構成は上記実施形態１の場合と基本的に同じであるので、同じ部分には同じ符号を付して示すこととする。
【００５４】
本実施形態では、第２の回転部材２が入力側とされており、このことで、本発明における初張力付与機構が構成されている。すなわち、第２の回転部材２の回転に伴って発生する遠心力により揺動部３の摩擦面２ａの周方向他端側（同図の右端側）が半径方向外方に変位して平ベルト４を押圧することで該平ベルト４に初張力を付与するようになされている。尚、その他の構成は上記実施形態１の場合と同じであるので、説明は省略する。
【００５５】
上記のように構成された一方向クラッチの作動について説明する。
【００５６】
上記一方向クラッチにおいて、第２の回転部材２に何れかの方向のトルクが入力されるとき、該回転部材２の回転に伴って平ベルト４に初張力が付与されるようになるので、上記トルクは平ベルト４を介して第１の回転部材１に伝達されようとし、一方、揺動部３はその揺動軸心Ｑの回りに回動する。
【００５７】
そして、上記第２の回転部材２がロック方向（図５の時計回り方向）に回転するときには、揺動部３は、同図に仮想線で示すように、該揺動部３の摩擦面２ａの周方向他端側が平ベルト４を押圧する方向（同図の反時計回り方向）に回動する。これにより、平ベルト４の初張力が上昇するので、一方向クラッチとしてはロック状態となる。
【００５８】
一方、上記第２の回転部材２が、上記の場合とは逆のフリー方向（図５の反時計回り方向）に回転するときには、揺動部３は、摩擦面２ａの周方向他端側が平ベルト４を押圧する方向とは逆の方向（同図の時計回り方向）に回動する。これにより、平ベルト４の初張力が減少することになるので、一方向クラッチとしてはフリー状態となる。
【００５９】
したがって、本実施形態によれば、第１の回転部材１に形成された断面円形状の摩擦面１ａと、第２回転部材２の有する揺動部３に形成された断面円弧状の摩擦面２ａとの間に平ベルト４を巻き掛け、両回転部材１，２の相対回転に伴って平ベルト４により揺動部３を揺動させ、その揺動部３の揺動により平ベルト４の初張力を増減させることで両回転部材１，２間でのトルク伝達の断接を行うようにした一方向クラッチにおいて、上記第２の回転部材２を入力側に設定し、該第２回転部材２の回転に伴って発生する遠心力により揺動部３を揺動させることにより平ベルト４に初張力を付与するようにしたので、上記実施形態１の場合における初張力付与機構の構成部品を省略することができ、よってさらなる低コスト化を図ることができる。
【００６０】
（実施形態３）
図６は、本発明の実施形態３に係る一方向クラッチの要部を示しており、この一方向クラッチの全体構成も上記実施形態１の場合と基本的に同じである。
【００６１】
本実施形態では、摩擦部材として、有端の平ベルト４が用いられており、その両端は揺動部３の周方向両端部の止着部２１ａ，２１ｂにビス２２を用いて止着されている。
【００６２】
そして、本実施形態では、上記揺動部３における一方（図６の左方）の止着部２１ａの側の揺動アーム長さＬ２に対する他方（同図の右方）の止着部２１ｂの側の揺動アーム長さＬ１の比Ｌ１／Ｌ２が、第１回転部材１の摩擦面１ａと平ベルト４との間の摩擦係数μ１′にその接触角度θ１を乗算した値μ１′・θ１だけ自然対数の底ｅが累乗されてなる値ｅμ^１′・θ^１に基づいて設定されている。尚、その他の構成は実施形態１の場合と同じであるので説明は省略する。
【００６３】
したがって、本実施形態によれば、有端の平ベルト４を用い、その両端を第２の回転部材２の揺動部３に止着するようにしたので、平ベルト４と第１の回転部材１の摩擦面１ａとの間のトルク伝達の断接を通じて、上記実施形態１の場合と略同じ効果を奏することができる。
【００６４】
（実施形態４）
図７は、本発明の実施形態４に係る一方向クラッチの要部を示しており、この一方向クラッチの全体構成も上記実施形態１の場合と基本的に同じである。
【００６５】
本実施形態では、上記実施形態２の場合と同様に第２の回転部材２が入力側とされており、このことで、本発明における初張力付与機構が構成されている。
【００６６】
また、本実施形態では、上記実施形態３の場合と同じく、摩擦部材として有端の平ベルト４が用いられていて、その両端は揺動部３の周方向両端部の止着部２１ａ，２１ｂにビス２２により止着されている。尚、その他の構成は実施形態１の場合と同じであるので説明は省略する。
【００６７】
したがって、本実施形態によれば、第２の回転部材２を入力側に設定することで初張力付与機構を構成するとともに、有端の平ベルト４を用いて、その両端を第２の回転部材２の揺動部３に止着するようにしたので、上記実施形態２と上記実施形態３とを併せた場合と同じ効果を奏することができる。
【００６８】
【発明の効果】
以上説明したように、請求項１の発明によれば、外周に断面円形状の摩擦面が形成された第１の回転部材と、外周に断面円弧状の摩擦面が形成されているとともに該摩擦面の周方向一端側に偏った位置において揺動可能に枢支された揺動部を有し、該第１の回転部材に上記中心軸線回りに相対回転可能に組み付けられた第２の回転部材と、これら第１及び第２回転部材の両摩擦面間に巻き掛けられた無端の摩擦部材と、両回転部材が一方向に相対回転するときには上記摩擦部材が揺動部を該摩擦部材の初張力を増加させる方向に回動させる一方、両回転部材が他方向に相対回転するときには上記摩擦部材が揺動部を該摩擦部材の初張力を減少させる方向に回動させるようにするとともに、上記第１回転部材の摩擦面と摩擦部材との間の摩擦係数及び接触角度をそれぞれμ１′及びθ１とし、かつ第２回転部材の摩擦面と上記摩擦部材との間の摩擦係数及び接触角度をそれぞれμ２′及びθ２としたときに、上記揺動部における摩擦面の周方向一端側の揺動アーム長さＬ２に対する該摩擦面の周方向他端側の揺動アーム長さＬ１の比Ｌ１／Ｌ２を、Ｌ１／Ｌ２≦ｅμ^１′・θ^１及びＬ１／Ｌ２≦ｅμ^２′・θ^２の２つの関係式（但し、ｅは自然対数の底であり、θ１及びθ２の単位はラジアンである）を共に満たすように設定して、上記第１及び第２回転部材の各摩擦面と摩擦部材との間に滑りを生じさせないようにしたので、簡単な構造でありかつ高精度が要求されなくて低コストでありながら、入力トルクの方向に応じて第１及び第２の回転部材の少なくとも一方と摩擦部材との間でトルク伝達の断接を行うことができるとともに、過度の入力トルクに対しては摩擦部材の破断により出力自体を停止させるようにすることができ、しかも破断した摩擦部材の交換は容易であり、摩擦部材の交換により再使用することができる。
【００６９】
請求項２の発明によれば、外周に断面円形状の摩擦面が形成された第１の回転部材と、２つの止着部が周方向にずれて設けられているとともに一方の止着部の側に偏った位置において揺動可能に枢支された揺動部を有し、該第１の回転部材に上記中心軸線回りに相対回転可能に組み付けられた第２の回転部材と、第１回転部材の摩擦面に巻き掛けられているとともに両端がそれぞれ第２回転部材の揺動部の対応する止着部に止着された有端の摩擦部材と、両回転部材が一方向に相対回転するときには上記摩擦部材が揺動部を該摩擦部材の初張力を増加させる方向に回動させる一方、両回転部材が他方向に相対回転するときには上記摩擦部材が揺動部を該摩擦部材の初張力を減少させる方向に回動させるようにするとともに、上記第１の回転部材の摩擦面と摩擦部材との間の摩擦係数及び接触角度をそれぞれμ１′及びθ１としたときに、上記揺動部における一方の止着部の側の揺動アーム長さＬ２に対する他方の止着部の側の揺動アーム長さＬ１の比Ｌ１／Ｌ２を、Ｌ１／Ｌ２≦ｅμ^１′・θ^１の関係式を満たすように設定して、上記第１回転部材の摩擦面と摩擦部材との間に滑りを発生させないようにしたので、上記請求項１の発明の場合と略同じ効果を奏することができる。
【図面の簡単な説明】
【図１】本発明の実施形態１に係る一方向クラッチを模式的に示す正面図である。
【図２】一方向クラッチの内部を示す正面図である。
【図３】図２のＩＩＩ −ＩＩＩ線断面図である。
【図４】Ｖプーリが取り付けられた状態を示す図６相当図である。
【図５】本発明の実施形態２に係る一方向クラッチを示す図２相当図である。
【図６】本発明の実施形態３に係る一方向クラッチを示す図２相当図である。
【図７】本発明の実施形態４に係る一方向クラッチを示す図２相当図である。
【図８】従来の一方向クラッチとしてのローラ式一方向クラッチの要部を模式的に示す断面図である。
【符号の説明】
１第１の回転部材
１ａ摩擦面
２第２の回転部材
２ａ摩擦面
３揺動部
４平ベルト（摩擦部材）
５板ばね（初張力付与機構）
２１ａ，２１ｂ止着部
Ｐ中心軸線
Ｑ揺動軸心
Ｌ１揺動部における摩擦面の周方向他端側の揺動アーム長さ、
揺動部における他方の止着部の側の揺動アーム長さ
Ｌ２揺動部における摩擦面の周方向一端側の揺動アーム長さ、
揺動部における一方の止着部の側の揺動アーム長さ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a low-cost one-way clutch that has a simple structure and does not require high precision, and particularly relates to a measure against excessive input torque.
[0002]
[Prior art]
Generally, as a one-way clutch used for an automobile, an agricultural machine, an OA machine, and the like, a roller-type clutch and a sprag-type clutch are well known.
[0003]
As an example of a conventional one-way clutch, a roller-type one-way clutch will be described. As schematically shown in FIG. 8, an inner race a, and an outer race b which is rotatably assembled to the inner race a, A plurality (only one is shown in the figure) of recesses c, c,... Provided in the inner periphery of the outer race b at a predetermined pitch in the circumferential direction, and are respectively disposed in the recesses c. FIG. 4 is a diagram for urging the rollers d in a direction (counterclockwise direction in the illustrated example) in which the rollers d are sandwiched between the outer peripheral surface e of the inner race a and the inner peripheral surface f of the outer race b. It has an outer spring.
[0004]
For example, when a torque is input to the inner race a in the same direction as the biasing direction of the spring (counterclockwise direction in the drawing), each roller d rotates the outer circumferential surface e of the inner race a and the inner circumferential surface of the outer race b. Since it is sandwiched between the inner race a and the inner race a, the torque input to the inner race a is transmitted to the outer race b. On the other hand, when a torque in a direction opposite to the above-mentioned biasing direction (clockwise direction in the figure) is input, each roller d is not pinched between the races a and b, and the inner race a is free from the outer race b. Rotate in state. That is, at this time, the torque of the inner race a is not transmitted to the outer race b.
[0005]
[Problems to be solved by the invention]
However, the above-described conventional one-way clutch has a problem that it is difficult to obtain it at a low cost because it requires extremely high-precision parts and has a complicated structure.
[0006]
In addition, when a torque exceeding the maximum transmission torque of the one-way clutch is input and the clutch is damaged, there is a problem that the clutch itself has to be replaced, instead of just replacing parts. Therefore, in order to cope with such a situation, a torque limiter must be separately provided, which further increases the cost.
[0007]
Further, when an excessive torque is input without exceeding the maximum transmission torque, there is a problem that the torque is output as it is. Therefore, a torque limiter is required to prevent such a situation.
[0008]
The present invention has been made in view of the above points, and a main object of the present invention is to transmit torque between both shafts when an initial tension is applied to a belt wound between the two shafts, By applying the principle of the belt transmission mechanism that does not transmit torque when the torque is not applied, the structure is simple, high accuracy is not required, the cost is low, and the output torque is The object is to provide a one-way clutch that can be suppressed.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, in a two-axis belt transmission mechanism, one of the shafts is provided with a rocking portion that rocks so as to increase or decrease the initial tension of the belt according to the relative rotation direction of both shafts. As a result, the function as a one-way clutch can be exhibited. Also, at that time, paying attention to the fact that the occurrence rate of belt slip increases with an increase in input torque, by enabling the slip to be controlled, the belt can be controlled against excessive input torque.BreakingOutput torque can be suppressed by disconnection.
[0010]
More specifically, according to the first aspect of the present invention, a first rotating member having a friction surface having a circular cross section formed on the outer periphery, and a cross section located radially outward of the friction surface of the first rotating member on the outer periphery. An arc-shaped friction surface is formed, and a pivotally pivotally supported pivotally about an axis parallel to a center axis of the friction surface of the first rotating member at a position deviated to one circumferential end of the friction surface. A second rotating member having a moving part and assembled to the first rotating member so as to be relatively rotatable around the central axis, and wound around both friction surfaces of the first and second rotating members; When the endless friction member and the two rotating members are relatively rotated in one direction (hereinafter, referred to as a lock direction), the friction member displaces the swinging portion at the other circumferential end of the friction surface in a radially outward direction. To rotate the friction member in a direction to increase the initial tension. When the friction member relatively rotates in the other direction (hereinafter, referred to as a free direction), the friction member displaces the swinging portion in a direction in which the other end of the friction surface in the circumferential direction is displaced radially inward to reduce the initial tension of the friction member. An initial tension applying mechanism for applying an initial tension to each of the friction members so as to rotate is provided. The friction coefficient and the contact angle between the friction surface of the first rotating member and the friction member are set to μ1 ′ and θ1, respectively, and the friction coefficient between the friction surface of the second rotating member and the friction member is set to μ1 ′ and θ1. When the contact angle is μ2 ′ and θ2, respectively, the swing arm length L1 at the other end in the circumferential direction of the friction surface with respect to the swing arm length L2 at one end in the circumferential direction of the friction surface in the swing portion. Ratio L1 / L2 (hereinafter referred to as swing arm ratio) is
L1 / L2 ≦ eμ¹'・ Θ¹
L1 / L2 ≦ eμ²'・ Θ²
It is assumed that the two relational expressions are set to satisfy both.
[0011]
In the above configuration, when a torque is input to one of the first and second rotating members and the two rotating members relatively rotate in either direction, the first and second rotating members are changed according to the rotation direction. The connection and disconnection of the torque transmission between them is performed.
[0012]
That is, when the two rotating members rotate relative to each other in the locking direction, the oscillating portion is moved radially outward at the other end in the circumferential direction of the friction surface by the friction member to which the initial tension is applied by the initial tension applying mechanism. The friction member is displaced and rotated in a direction to increase the initial tension of the friction member. Therefore, at this time, since the grip force between each friction surface of the first and second rotating members and the friction member increases, the torque between the first and second rotating members is transmitted through the friction member. Is transmitted.
[0013]
On the other hand, when the two rotating members rotate relative to each other in the free direction, the oscillating portion rotates in a direction in which the other end of the friction surface in the circumferential direction is displaced inward in the radial direction to reduce the initial tension of the friction member. Therefore, the grip force between each friction surface of the first and second rotating members and the friction member is lost, so that at this time, torque transmission between the first and second rotating members is not performed.
[0014]
Further, when the input torque increases when the two rotating members rotate relative to each other in the locking direction to transmit torque, the tension side and the loose side tension of the friction member increase accordingly. The maximum transmission torque and the slip occurrence rate of the friction member both increase. At this time, the slip occurrence rate is determined by determining the ratio t1 / t2 of the tension side tension t1 and the loose side tension t2 of the friction member to the friction coefficient between the friction member and each friction surface and the contact angle [unit: [Radian] increases rapidly as the value approaches the value raised to the power of the natural logarithm, and when the value exceeds that value, an attempt is made to shift to a state where the occurrence rate becomes 100%.
[0015]
At this time, if the slip occurrence rate reaches 100% when the tension side tension t1 of the friction member is within the range of the allowable tension, slippage of the friction member occurs, so that the input torque is reduced. Even if it rises further, only a substantially constant torque is transmitted between the two rotating members while the friction member slides. That is, in this case, only a substantially constant torque is output with respect to the excessive input torque.
[0016]
Conversely, if the slippage occurrence rate does not reach 100% when the tension side tension t1 is within the range of the allowable tension, the friction member is broken and the torque between the two rotating members is reduced. Transmission is stopped. That is, in this case, the output of the torque itself is stopped with respect to the excessive input torque. The one-way clutch in which the friction member is broken can be reused by replacing the friction member, and the replacement of the friction member itself is relatively easy.
[0017]
Next, occurrence of slippage of the friction member will be described in detail. For example, the ratio T1 / T2 of the tension T1 and the tension T2 of the friction member when the friction member slides with the friction surface of the first rotation member, and the friction of the first rotation member. As described above, between the friction coefficient μ1 ′ between the surface and the friction member and the contact angle θ1,
T1 / T2> eμ¹'・ Θ¹
(Where e is the base of a natural constant). That is, when the ratio t1 / t2 of the tension side tension t1 and the loose side tension t2 of the friction member is equal to or greater than T1 / T2 (t1 / t2 ≧ T1 / T2), the friction member slips, and conversely, T1 If it is smaller than / T2 (t1 / t2 <T1 / T2), no sliding of the friction member occurs, and the friction member breaks.
[0018]
Here, when the moment acting on one end in the circumferential direction of the swing portion and the moment acting on the other end in the circumferential direction are balanced with each other, the swing arm length L2 and the friction member on one end in the circumferential direction are balanced. Between the tension side tension t1 and the swing arm length L1 on the other end in the circumferential direction and the loose side tension t2 of the friction member, L2 · t1 = L1 · t2, so that t1 / t2 = L1 / L2 is established.
[0019]
Accordingly, when the input torque increases due to the relative rotation of the first and second rotating members in the locking direction, the swing arm ratio L1 / L2 of the swinging portion is determined by the friction surface of the first rotating member and the friction member. Is a value obtained by raising the base e of the natural logarithm to the power μ1 ′ · θ1 obtained by multiplying the friction coefficient μ1 ′ between the coefficient and the contact angle θ1 by e1.¹'・ Θ¹The following (L1 / L2 ≦ eμ)¹'・ Θ¹), The tension ratio t1 / t2 of the friction member is smaller than the tension ratio T1 / T2 when slippage occurs (t1 / t2 = L1 / L2 ≦ eμ).¹'・ Θ¹<T1 / T2). Therefore, the slip ratio of the friction member does not reach 100%, and no slip occurs between the friction member and the friction surface of the first rotating member.
[0020]
Further, the swing arm ratio L1 / L2 is such that the base e of the natural logarithm is equal to a value μ2 ′ · θ2 obtained by multiplying the friction coefficient μ2 ′ between the friction surface of the second rotating member and the friction member by the contact angle θ2. Value eμ raised to the power²'・ Θ²The following (L1 / L2 ≦ eμ)²'・ Θ²), The tension ratio t1 / t2 of the friction member is larger than the tension ratio T1 / T2 when the friction member slides between the friction member and the friction surface of the second rotating member. Small (t1 / t2 = L1 / L2 ≦ eμ)²'・ Θ²<T1 / T2) is suppressed, so that no slip occurs between the friction member and the friction surface of the swinging portion of the second rotating member.
[0021]
In other words, in the case of the present invention, only the maximum transmission torque between the first and second rotating members continues to increase in accordance with the increase in the input torque, and the maximum transmission torque exceeds the allowable tension of the friction member. The friction member breaks.
[0022]
Claim2In the invention, a first rotating member having a friction surface with a circular cross section formed on the outer periphery, and two fastening portions shifted in a circumferential direction from each other are provided radially outward of the friction surface of the first rotating member. And at a position deviated toward one of the two fastening portions, the first rotating member is pivotally supported so as to be swingable about an axis parallel to a center axis of a friction surface of the first rotating member. A second rotating member which has a swinging portion and is rotatably assembled to the first rotating member so as to be relatively rotatable around the central axis, and is wound around a friction surface of the first rotating member. At the same time, when the two rotating members rotate relative to each other in the locking direction, the friction member is an endless friction member having both ends fixed to corresponding fastening portions of the swinging portion of the second rotating member. The other fastening portion displaces the swinging portion radially outward to reduce the initial tension of the friction member. When the two rotating members rotate relative to each other in the free direction, the friction member displaces the oscillating portion and the other fastening portion displaces radially inward to reduce the initial tension of the friction member. An initial tension applying mechanism for applying an initial tension to each of the friction members so as to rotate in the decreasing direction is provided.
Then, when the friction coefficient and the contact angle between the friction surface of the first rotating member and the friction member are μ1 ′ and θ1, respectively, a swing arm on one of the fastening portions of the swing portion. The ratio L1 / L2 of the swing arm length L1 on the other fastening portion side to the length L2 is:
L1 / L2 ≦ eμ¹'・ Θ¹
Are set so as to satisfy the relational expression.
[0023]
In the above configuration, the friction member has an end unlike the case of the first and second aspects of the invention, and both ends of the friction member are fixed to the corresponding fixing portions of the swinging portion of the second rotating member. Therefore, it rotates integrally with the second rotating member. Therefore, the connection and disconnection of the torque transmission between the first and second rotating members is performed only between the friction member and the friction surface of the first rotating member.DoneIt is.
[0024]
When the input torque increases due to the relative rotation of the first and second rotating members in the locking direction, the swing portion relative to the swing arm length L2 of one of the fastening portions on the side of the swing portion. The ratio L1 / L2 of the length L1 of the swing arm on the side of the other fixing portion at the time of (1) is obtained by multiplying the friction coefficient μ1 ′ between the friction surface of the first rotating member and the friction member by the contact angle θ1. A value eμ obtained by raising the base e of the natural logarithm to the power of the value μ1 ′ · θ1.¹'・ Θ¹The following (L1 / L2 ≦ eμ)¹'・ Θ¹), The tension ratio t1 / t2 of the friction member is smaller than the tension ratio T1 / T2 of the friction member when slippage occurs (t1 / t2 = L1 / L2). L2 ≦ eμ¹'・ Θ¹<T1 / T2), the slip ratio of the friction member does not reach 100%, and no slip occurs between the friction member and the friction surface of the first rotating member. Therefore, in the case of the present invention, as in the case of the second aspect of the invention, only the maximum transmission torque between the first and second rotating members continues to increase until the friction member breaks according to the increase in the input torque. .
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0026]
(Embodiment 1)
2 and 3 show a one-way clutch according to the first embodiment of the present invention. This one-way clutch is disposed at an output end of a power take-out device (PTO) in a vehicle having a power take-out device (PTO), for example. In addition, it is used by being arranged at an input end of a mowing mechanism in a combine as an agricultural machine, and at an input end of a planting mechanism in a rice transplanter.
[0027]
The one-way clutch includes a first rotating member 1 having a friction surface 1 a having a circular cross section formed on the outer periphery, and an arc-shaped cross section located radially outward of the friction surface 1 a of the first rotating member 1 on the outer periphery. At the position where the friction surface 2a is formed and which is deviated to one end in the circumferential direction of the friction surface 2a (left end in FIG. 2), the axis Q of the friction surface 1a of the first rotating member 1 is parallel to the center axis P of the friction surface 1a. A second rotating member 2 having a swinging portion 3 which can swing around, and which is assembled to the first rotating member 1 so as to be relatively rotatable around a central axis P; It is wound between the friction surfaces 1a and 2a of the

members

1 and 2, and the rocking unit 3 is rocked with the relative rotation of the

rotating members

1 and 2 in a state where the initial tension is applied. A rubber flat belt 4 as an endless friction member whose initial tension increases and decreases due to the rocking, Doo 4 and a leaf spring 5 serving as a first tensioning mechanism for imparting the initial tension.
[0028]
More specifically, the first rotating member 1 is formed of a flat pulley, and its boss 1b extends so as to protrude leftward in FIG. A key groove 6 for key connection with a shaft (not shown) connected to the boss 1b is provided along the center axis P on the inner periphery of the boss 1b.
[0029]
On the other hand, the second rotating member 2 has a cup-shaped main body 7 rotatably mounted on the boss 1b of the first rotating member 1 via a bearing 8 at a boss portion 7a, and an opening of the main body 7. And a disk-shaped cover member 10 attached to the main body 7 by a plurality of

bolts

9, 9,. As shown in FIG. 3, the bearing 8 is arranged in the same plane as the flat belt 4, so that no moment due to the tension of the flat belt 4 acts on the bearing 8. In the center of the cover member 10, a circular opening 10a corresponding to the boss 1b of the first rotating member 1 is provided.
[0030]
The oscillating portion 3 has an arc shape whose inner and outer circumferences are both arc-shaped in cross section, and an oscillating shaft is formed by a pivot pin 11 whose both ends are supported on a main body 7 and a cover member 10 of the second rotating member 2. It is swingably supported around the center Q. Both ends in the circumferential direction of the friction surface 2a of the oscillating portion 3 are formed in an arc-shaped cross section having a smaller curvature than the other portions, so as to avoid bending of the flat belt 4 at both ends, The smooth belt 4 is smoothly introduced and led out.
[0031]
Further, the swing arm 3 has a swing arm length L2 at one end in the circumferential direction of the swing axis Q (left end side in FIG. 2) on the friction surface 2a, and the swing axis Q on the friction surface 2a. Is set smaller (L2 <L1) than the swing arm length L1 at the other end in the circumferential direction (the right end side in the figure). More specifically, the pivot axis Q is arranged so as to be biased toward one end of the friction surface 2a in the circumferential direction in the direction in which the line segment extends, with respect to the midpoint of the line connecting the circumferential ends of the friction surface 2a. . Then, between the pivot axis Q in the direction of a straight line passing through both circumferential ends of the friction surface 2a of the rocking portion 3 (left-right direction in the figure) and one end of the friction surface 2a of the rocking portion 3 in the circumferential direction. The distance is the length L2 of the swing arm at the one end, and the distance between the swing axis Q in the same linear direction and the other end in the circumferential direction of the friction surface 2a of the swing portion 3 is the length of the other end. The swing arm length is L1.
[0032]
Therefore, when the first and second

rotating members

1 and 2 rotate relative to each other in the locking direction, for example, when the first rotating member 1 rotates counterclockwise in FIG. As shown by the imaginary line in the figure, the other end of the friction surface 2a in the circumferential direction is displaced radially outward, that is, rotates in the direction of pressing the flat belt 4, thereby increasing the initial tension of the flat belt 4. On the other hand, when the first and second

rotating members

1 and 2 relatively rotate in the free direction, for example, when the first rotating member 1 rotates clockwise in FIG. The flat belt 4 is rotated in the direction in which the side is displaced inward in the radial direction, that is, in the direction opposite to the direction in which the flat belt 4 is pressed, so that the initial tension of the flat belt 4 is reduced.
[0033]
As shown by the imaginary line in FIG. 2, the leaf spring 5 pushes the oscillating portion 3 at the other end in the circumferential direction of the friction surface 2 a of the oscillating portion 3 (the right end in FIG. 2) against the flat belt 4. It is arranged so as to always rotate and bias in the direction (clockwise direction in the figure). The leaf spring 5 is fixed at its base end to the inner peripheral surface of the main body 7 of the second rotating member 2 by bolts 12, and one or both sides of the swing portion 3 in the swing axis direction are pressed by the tip end thereof. It has been made to be.
[0034]
Further, as shown in FIG. 4, a V pulley 13 as an input / output wheel of the second rotating member 2 is detachably attached to the main body 7 of the second rotating member 2. That is, at a plurality of locations in the circumferential direction of the main body 7, bolt holes 7 a, 7 a,... For screwing the tips of the mounting bolts 14, 14 a,. Is provided in advance. A locking groove 16 for fitting a C-ring 15 is provided around the outer periphery of the boss portion 1b of the first rotating member 1, so that the V pulley 13 and the first rotating member 1 The bearing 17 interposed between the boss portion 1b and the boss portion 1b is locked.
[0035]
In this embodiment, the ratio L1 / L1 of the swing arm length L1 at the other end in the circumferential direction of the friction surface 2a to the swing arm length L2 at one end in the circumferential direction of the friction surface 2a in the swing portion 3 is described. L2 (oscillating arm ratio) is calculated by multiplying the friction coefficient μ1 ′ between the friction surface 1a of the first rotating member 1 and the flat belt 4 by the contact angle θ1 to obtain the natural logarithm base e by μ1 ′ · θ1. Value eμ raised to the power¹'・ Θ¹And a value eμ obtained by raising the natural logarithm base e to a value μ2 ′ · θ2 obtained by multiplying the friction coefficient μ2 ′ between the friction surface 2a of the second rotating member 2 and the flat belt 4 by the contact angle θ2.²'・ Θ²And is set based on.
[0036]
That is, no slippage occurs between the flat belt 4 and the friction surfaces 1a, 2a of the first and second

rotating members

1, 2 regardless of the magnitude of the input torque to the one-way clutch. The swing arm ratio L1 / L2 is
L1 / L2 ≦ eμ¹'・ Θ¹    ・・・ ▲ 1 ▼
L1 / L2 ≦ eμ²'・ Θ²    ... ▲ 2 ▼
Are set so as to satisfy both of the two relational expressions (1) and (2).
[0037]
On the other hand, when the input torque to the one-way clutch is increased, a slip is generated between the flat belt 4 and at least one of the friction surfaces 1a and 2a of the first and second rotating members 1. Is that the swing arm ratio L1 / L2 is
L1 / L2> eμ¹'・ Θ¹  ・・・ ▲ 3 ▼
L1 / L2> eμ²'・ Θ²    ・・・ ▲ 4 ▼
Are set so as to satisfy at least one of the two relational expressions (3) and (4).
[0038]
Here, the operation of the one-way clutch configured as described above will be described by taking a case where torque is input to the first rotating member 1 as an example.
[0039]
When the first rotating member 1 rotates in the free direction (clockwise direction in FIG. 2), the swinging part 3 rotates in the direction (same clockwise direction) in which the initial tension of the flat belt 4 decreases. No torque transmission is performed between the first and second

rotating members

1 and 2.
[0040]
On the other hand, when the first rotating member 1 rotates in the locking direction (counterclockwise direction in FIG. 2), the swinging unit 3 rotates in the direction to increase the initial tension of the flat belt 4 (counterclockwise direction). Therefore, torque is transmitted between the first and second

rotating members

1 and 2. Then, when the input torque increases, the slip occurrence rate of the flat belt 4 and the maximum transmission torque both increase accordingly.
[0041]
At this time, if the swing arm ratio L1 / L2 is set so as to satisfy both of the relational expressions (1) and (2), as described in the section of "Means for Solving the Problem" in detail. The ratio t1 / t2 of the tension on the tension side t1 of the flat belt 4 (in this case, the tension on the left side in FIG. 2) and the tension on the loose side t2 (in this case, the tension on the right side in FIG. 2) is the first. Is smaller than the ratio T1 / T2 (t1 / t2 <T1 / T2) of the tension T1 and the tension T2 of the flat belt 4 when slippage occurs between the friction member 1 and the friction surface 1a of the rotating member 1. Therefore, no slippage occurs between the friction surface 1a of the first rotating member 1 and the flat belt 4. Further, the tension ratio t1 / t2 of the flat belt 4 is smaller than the tension ratio T1 / T2 of the flat belt 4 when slippage occurs with the friction surface 1a of the first rotating member 1 (t1 / t2). <T1 / T2) is suppressed, so that no slip occurs between the friction surface 1a of the first rotating member 1 and the flat belt 4. Therefore, in this case, only the maximum transmission torque between the first and second

rotating members

1 and 2 continues to rise until the flat belt 4 breaks in accordance with the input torque, and the flat torque is not applied to excessive input torque. The output of the torque itself is stopped by the breakage of the belt 4. When the flat belt 4 is broken, the one-way clutch can be reused by replacing the flat belt 4.
[0042]
On the other hand, when the swing arm ratio L1 / L2 is set so as to satisfy at least one of the relational expressions (3) and (4), the tension ratio of the flat belt 4 is opposite to the above case. Since t1 / t2 reaches the tension ratio T1 / T2 at the time of occurrence of slip (t1 / t2 ≧ T1 / T2), the distance between the flat belt 4 and the friction surface 1a of the first rotating member 1 and between the flat belt 4 and At least one of the second rotating member 2 and the friction surface 2a, that is, when the relational expression (3) is satisfied, the frictional surface 1a of the first rotating member 1 and the relational expression When the condition (4) is satisfied, slippage occurs between the second rotating member 2 and the friction surface 2a. After the occurrence of slip, even if the input torque increases, only a substantially constant torque is transmitted between the

rotating members

1 and 2. Therefore, in this case, only a substantially constant torque is output due to slippage of the flat belt 4 with respect to the excessive input torque.
[0043]
Therefore, according to the one-way clutch according to the present embodiment, the friction surface 1 a having a circular cross section formed on the first rotating member 1 and the cross-sectional circle formed on the oscillating portion 3 of the second rotating member 2. An endless flat belt 4 is wound around the arc-shaped friction surface 2a, and the swing unit 3 is swung by the flat belt 4 with the relative rotation of the

rotating members

1 and 2, and the swing unit 3 swings. The torque transmission between the two

rotating members

1 and 2 is connected and disconnected by increasing and decreasing the initial tension of the flat belt 4 by movement, so that the structure is simple, high accuracy is not required and low cost. In addition, for an excessive input torque, the output torque can be suppressed by outputting only a substantially constant torque by sliding the flat belt 4 or stopping the output itself due to breakage of the flat belt 4.
[0044]
Further, the swing arm ratio L1 / L2 of the swing unit 3 is calculated by multiplying a friction coefficient μ1 ′ between the friction surface 1a of the first rotating member 1 and the flat belt 4 by a contact angle θ1 ′. Value eμ obtained by raising the base e of the natural logarithm to the power of θ1¹'・ Θ¹And the base e of the natural logarithm is raised by the value μ2 ′ · θ2 obtained by multiplying the friction coefficient μ2 ′ between the friction surface 2a of the swinging portion 3 of the second rotating member 2 and the flat belt 4 by the contact angle θ2. Value eμ²'・ Θ²And the slippage of the flat belt 4 is controlled based on this. For example, the flat belt 4 and each friction surface 1a,2a(T1 / T2> eμ)¹'・ Θ¹, Eμ²'・ Θ²), The slip can be controlled more easily than when the setting is performed by setting the tension ratio t1 / t2 of the flat belt 4, the friction coefficients μ1 ′ and μ2 ′, and the contact angles θ1 and θ2.
[0045]
In the above embodiment, the flat belt 4 made of rubber is used as the friction member. However, the material and shape are not particularly limited, and a metal hoop, for example, may be used.
[0046]
-Specific example-
Next, in the one-way clutch schematically shown in FIG. 1, a torque in the lock direction (clockwise direction in FIG. 1) is input to the first rotating member 1 so that the frictional surface 1 a of the rotating member 1 is flat. When slippage occurs between the flat belt 4 and the belt 4, the ratio T1 / T2 between the tension T1 and the loose tension T2 of the flat belt 4, the friction coefficient μ1 'between the friction surface 1a and the belt 4, and the contact Between the angle θ1 [unit: radian]
T1 / T2> eμ¹'・ Θ¹
Assuming that the following relational expression holds, the swing arm ratio L1 / L2 of the swing unit 3 when the slip occurs is also equal to the tension ratio T1 / T2 when the slip occurs, and as a result,
L1 / L2> eμ¹'・ Θ¹
It is explained that the relational expression holds. In this embodiment, the radius R of the friction surface 1a of the first rotating member 1 is R = 40.50 mm, the contact angle θ1 between the friction surface 1a and the flat belt 4 is θ1 = π, The length L2 of the swing arm at one circumferential end (left end in FIG. 1) of the friction surface 2a is set to L2 = 25.30 mm, and the length of the swing arm at the other circumferential end (right end in FIG. 1). L1 is set to L1 = 55.70 mm, and the center axis P of the swing axis Q in a direction (vertical direction in the figure) orthogonal to a linear direction (horizontal direction in the figure) passing through both circumferential ends of the friction surface 2a. Is set to 27.00 mm, respectively.
[0047]
First, the tension T1 and the tension T2 of the flat belt 4 at the time of occurrence of the slip are respectively:
T1 = effective tension × eμ¹'・ Θ¹/ (Eμ¹'・ Θ¹-1)
T2 = effective tension / (eμ¹'・ Θ¹-1)
Is represented by
[0048]
Here, assuming that the slippage occurs when a torque of 5 kgf-m is input to the first rotating member 1, the effective tension of the flat belt 4 at that time is as follows:
5 [kgf-m] /0.0405 [m] = 123.456 [kgf]
It is.
[0049]
Further, the swing arm ratio L1 / L2 of the swing unit 3 is:
Since L1 / L2 = 55.7 mm / 25.3 mm = 2.2015, μ1 ′ · θ1 becomes

And therefore eμ¹'・ Θ¹Is
eμ¹'・ Θ¹= E^0.789= 2.2. . .
It is.
[0050]
From these, when the tension T1 and the tension T2 on the tension side of the flat belt 4 are respectively obtained,

Therefore, the axial load applied to the swing axis Q of the swing portion 3 is:
T1 + T2 = 226.218 + 102.762 = 328.98 [kgf]
It becomes.
[0051]
Next, when the shaft load is converted into a torque for the first rotating member 1, the amount of eccentricity ((L1−L2) / 2) of the swing axis Q from the center axis P at this time is

Therefore, the torque is
328.98 x 0.0152 = 5.000. . . [Kgfm]
It becomes.
[0052]
Therefore, when a slip occurs between the friction surface 1a of the first rotating member 1 and the flat belt 4, the swing arm ratio L1 / L2 of the swing unit 3 is determined by the tension at the time when the flat belt 4 slips. Equal to the ratio T1 / T2, so that
L1 / L2> eμ¹'・ Θ¹
It can be seen that the relational expression holds.
[0053]
(Embodiment 2)
FIG. 5 shows a main part of a one-way clutch according to a second embodiment of the present invention. Since the entire configuration of the one-way clutch is basically the same as that of the first embodiment, The same reference numerals are given.
[0054]
In the present embodiment, the second rotating member 2 is on the input side, and this constitutes the initial tension applying mechanism of the present invention. That is, the other end in the circumferential direction of the friction surface 2a (the right end in the figure) of the friction surface 2a of the oscillating portion 3 is displaced radially outward by the centrifugal force generated with the rotation of the second rotating member 2, and the flat belt The initial tension is applied to the flat belt 4 by pressing the flat belt 4. The other configuration is the same as that of the first embodiment, and the description is omitted.
[0055]
The operation of the one-way clutch configured as described above will be described.
[0056]
In the one-way clutch, when torque in any direction is input to the second rotating member 2, the initial tension is applied to the flat belt 4 with the rotation of the rotating member 2. The torque tends to be transmitted to the first rotating member 1 via the flat belt 4, while the swinging unit 3 rotates around its swinging axis Q.
[0057]
When the second rotating member 2 rotates in the locking direction (clockwise direction in FIG. 5), the swinging part 3 moves as shown by a virtual line in FIG. Is rotated in a direction (counterclockwise direction in the figure) in which the other end in the circumferential direction presses the flat belt 4. As a result, the initial tension of the flat belt 4 increases, so that the one-way clutch is locked.
[0058]
On the other hand, when the second rotating member 2 rotates in a free direction (counterclockwise direction in FIG. 5) opposite to the above case, the swing unit 3Friction surfaceThe other end in the circumferential direction of 2a rotates in a direction opposite to the direction in which the flat belt 4 is pressed (clockwise direction in the figure). As a result, the initial tension of the flat belt 4 decreases, so that the one-way clutch is in a free state.
[0059]
Therefore, according to the present embodiment, the friction surface 1 a having a circular cross section formed on the first rotating member 1 and the friction surface 2 a having an arc-shaped cross section formed on the oscillating portion 3 of the second rotating member 2. And the swinging portion 3 is swung by the flat belt 4 in accordance with the relative rotation of the

rotating members

1 and 2, and the swinging of the swinging portion 3 causes the flat belt 4 to initially move. In the one-way clutch in which the torque transmission between the two

rotating members

1 and 2 is performed by increasing and decreasing the tension, the second rotating member 2 is set on the input side, and The initial tension is applied to the flat belt 4 by oscillating the oscillating portion 3 by the centrifugal force generated by the rotation of the shaft. Therefore, the components of the initial tension applying mechanism in the case of the first embodiment are omitted. And thus can further reduce costs
[0060]
(Embodiment 3)
FIG. 6 shows a main part of a one-way clutch according to a third embodiment of the present invention. The overall configuration of the one-way clutch is basically the same as that of the first embodiment.
[0061]
In the present embodiment, an endless flat belt 4 is used as a friction member, and both ends thereof are fastened to

fastening portions

21a and 21b at both ends in the circumferential direction of the swinging portion 3 using screws 22. I have.
[0062]
In the present embodiment, the other (the right-hand side) fastening portion 21b of the swinging portion 3 with respect to the swing arm length L2 on the side of the one (the left side in FIG. 6) fastening portion 21a. The ratio L1 / L2 of the side swing arm length L1 is the value μ1 ′ · θ1 obtained by multiplying the friction coefficient μ1 ′ between the friction surface 1a of the first rotating member 1 and the flat belt 4 by the contact angle θ1. Value eμ obtained by raising the base e of the natural logarithm to the power¹'・ Θ¹It is set based on. The other configuration is the same as that of the first embodiment, and the description is omitted.
[0063]
Therefore, according to the present embodiment, the endless flat belt 4 is used, and both ends of the flat belt 4 are fixed to the swinging portion 3 of the second rotating member 2. Through the connection and disconnection of the torque transmission between the first friction surface 1a and the first friction surface 1a, substantially the same effects as in the first embodiment can be obtained.
[0064]
(Embodiment 4)
FIG. 7 shows a main part of a one-way clutch according to a fourth embodiment of the present invention, and the entire configuration of the one-way clutch is basically the same as that of the first embodiment.
[0065]
In the present embodiment, the second rotating member 2 is on the input side as in the case of Embodiment 2 described above, and this constitutes the initial tension applying mechanism of the present invention.
[0066]
Further, in the present embodiment, as in the case of the third embodiment, the endless flat belt 4 is used as a friction member, and both ends of the flat belt 4 are fastening

portions

21a and 21b at both ends in the circumferential direction of the swinging portion 3. Are fixed by screws 22. The other configuration is the same as that of the first embodiment, and the description is omitted.
[0067]
Therefore, according to the present embodiment, the initial tension applying mechanism is configured by setting the second rotating member 2 on the input side, and both ends of the second rotating member 2 are connected to the second rotating member by using the flat belt 4 having an end. 2 so as to be fixed to the swing part 3 of the second embodiment.And the third embodiment.Same effect as whenPlayingcan do.
[0068]
【The invention's effect】
As described above, according to the first aspect of the present invention, the first rotating member having a friction surface having a circular cross section formed on the outer periphery, the friction member having an arc-shaped friction surface formed on the outer periphery, and A second rotating member having a swinging portion pivotally supported at a position deviated to one end side in the circumferential direction of the surface, and assembled to the first rotating member so as to be relatively rotatable around the central axis; An endless friction member wound between the friction surfaces of the first and second rotating members, and the friction member forms a swinging portion when the two rotating members rotate relative to one another in the first direction. While rotating in the direction of increasing the tension, when the two rotating members relatively rotate in the other direction, the friction member rotates the swinging part in the direction of decreasing the initial tension of the friction member, Frictional engagement between the friction surface of the first rotating member and the frictional member And the contact angle is μ1 ′ and θ1, respectively, and the friction coefficient and the contact angle between the friction surface of the second rotating member and the friction member are μ2 ′ and θ2, respectively. The ratio L1 / L2 of the swing arm length L1 at the other end in the circumferential direction of the friction surface to the swing arm length L2 at one end in the circumferential direction is L1 / L2 ≦ eμ.¹'・ Θ¹And L1 / L2 ≦ eμ²'・ Θ²(Where e is the base of the natural logarithm, and the units of θ1 and θ2 are radians), and the frictional surfaces of the first and second rotating members are Since no slippage is caused between the first and second rotating members according to the direction of the input torque, the structure has a simple structure, does not require high precision, and is low in cost. The torque transmission and disconnection can be performed between one side and the friction member, and the output itself can be stopped by breaking the friction member against excessive input torque, and the broken friction member Is easy to replace, and can be reused by replacing the friction member.
[0069]
Claim2According to the invention of the first aspect, the first rotating member having a friction surface having a circular cross section formed on the outer periphery and the two fastening portions are provided to be shifted in the circumferential direction and are biased toward one of the fastening portions. A second rotating member, which has a swinging portion pivotally supported in a swingable position, and is relatively rotatably mounted on the first rotating member around the central axis, and friction between the second rotating member and the first rotating member. A friction member having an end wound around the surface and having both ends fastened to corresponding fastening portions of the swinging portion of the second rotating member, and the above friction when the two rotating members rotate relative to each other in one direction. The member rotates the rocking portion in a direction to increase the initial tension of the friction member, while the friction member reduces the rocking portion to reduce the initial tension of the friction member when both rotating members rotate relative to each other in the other direction. And the friction of the first rotating member. When the coefficient of friction and the contact angle between the friction member and the friction member are μ1 ′ and θ1, respectively, the side of the other fastening portion relative to the swing arm length L2 of one of the fastening portions in the swing portion is described. The ratio L1 / L2 of the oscillating arm length L1 to L1 / L2 ≦ eμ¹'・ Θ¹Is set so as to satisfy the following relational expression so as not to cause slippage between the friction surface of the first rotating member and the friction member, so that substantially the same effect as in the case of the invention of claim 1 can be obtained. Can be.
[Brief description of the drawings]
FIG. 1 is a front view schematically showing a one-way clutch according to a first embodiment of the present invention.
FIG. 2 is a front view showing the inside of a one-way clutch.
FIG. 3 is a sectional view taken along line III-III of FIG. 2;
FIG. 4 is a view corresponding to FIG. 6, showing a state in which a V pulley is attached.
FIG. 5 is a diagram corresponding to FIG. 2, showing a one-way clutch according to a second embodiment of the present invention.
FIG. 6 is a diagram corresponding to FIG. 2, showing a one-way clutch according to Embodiment 3 of the present invention.
FIG. 7 is a diagram corresponding to FIG. 2, illustrating a one-way clutch according to a fourth embodiment of the present invention.
FIG. 8 is a cross-sectional view schematically showing a main part of a roller-type one-way clutch as a conventional one-way clutch.
[Explanation of symbols]
1 First rotating member
1a Friction surface
2 Second rotating member
2a Friction surface
3 swing part
4 Flat belt (friction member)
5 Leaf spring (initial tension applying mechanism)
21a, 21b fastening part
P center axis
Q Oscillating axis
L1 swing arm length at the other end in the circumferential direction of the friction surface in the swing portion,
Length of the swing arm on the side of the other fastening part in the swing part
L2 Length of the swing arm at one end in the circumferential direction of the friction surface in the swing portion,
Length of the swing arm on the side of one of the fastening parts in the swing part

Claims

A first rotating member having a friction surface with a circular cross section formed on the outer periphery;
A friction surface having an arc-shaped cross section located radially outward of the friction surface of the first rotating member is formed on the outer periphery, and the first rotating member is located at a position biased toward one circumferential end of the friction surface. A swinging portion pivotally supported so as to be able to swing around an axis parallel to the center axis of the friction surface, and a second rotating member assembled to the first rotating member so as to be relatively rotatable around the center axis. A rotating member;
An endless friction member wound between a friction surface of the first rotating member and a friction surface of the second rotating member;
When the first and second rotating members rotate relative to each other in one direction, the friction member displaces the oscillating portion at the other circumferential end of the friction surface radially outward to reduce the initial tension of the friction member. When the first and second rotating members are relatively rotated in the other direction, the friction member displaces the rocking portion at the other circumferential end of the friction surface radially inward. An initial tension applying mechanism for applying an initial tension to the friction member so as to rotate in a direction to decrease the initial tension of the friction member.
The coefficient of friction and the contact angle between the friction surface of the first rotating member and the friction member are μ1 ′ and θ1, respectively, and the coefficient of friction between the friction surface of the second rotating member and the friction member. When the contact angle is μ2 ′ and θ2, respectively, the swing arm length L1 at the other end in the circumferential direction of the friction surface with respect to the swing arm length L2 at one end in the circumferential direction of the friction surface in the swing portion. The ratio L1 / L2 of
L1 / L2 ≦ eμ ¹ ′ · θ ¹
L1 / L2 ≦ eμ ² ′ · θ ²
(Where e is the base of the natural logarithm, and the units of θ1 and θ2 are radians).

A first rotating member having a friction surface with a circular cross section formed on the outer periphery;
Two fastening portions that are circumferentially shifted from each other are provided radially outward of the friction surface of the first rotating member, and are biased toward one of the two fastening portions. A pivoting portion pivotally supported about an axis parallel to a central axis of the friction surface of the first rotating member at a position where the first rotating member is pivoted. A second rotating member rotatably assembled;
An end friction member wound around the friction surface of the first rotating member and having both ends fastened to corresponding fastening portions of the swinging portion of the second rotating member, When the first and second rotating members relatively rotate in one direction, the friction member displaces the rocking portion on the side of the other one of the two fastening portions in a radially outward direction, thereby causing the friction. When the first and second rotating members are rotated relative to each other in the direction in which the initial tension of the member is increased, the friction member causes the swinging portion to move in the radial direction with the other fastening portion being in the radial direction. An initial tension applying mechanism for applying an initial tension to each of the friction members so as to be displaced in a direction to rotate in a direction to decrease the initial tension of the friction member,
When the friction coefficient and the contact angle between the friction surface of the first rotating member and the friction member are μ1 ′ and θ1, respectively, a swing arm on the one fastening portion side of the swing portion. The ratio L1 / L2 of the swing arm length L1 on the other fastening portion side to the length L2 is:
L1 / L2 ≦ eμ ¹ ′ · θ ¹
(Where e is the base of the natural logarithm and the unit of θ1 is radian)
A one-way clutch set to satisfy the following relational expression: