JP2004353731A

JP2004353731A - Driving force transmitting device

Info

Publication number: JP2004353731A
Application number: JP2003150815A
Authority: JP
Inventors: Toshimi Hara; 利美原; Kunihiko Suzuki; 邦彦鈴木
Original assignee: Toyoda Koki KK
Current assignee: Toyoda Koki KK
Priority date: 2003-05-28
Filing date: 2003-05-28
Publication date: 2004-12-16

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving force transmitting device capable of allowing outer clutch plates to smoothly follow even when the clearance is axially generated because of the abrasion of the clutch plate, and improving the durability with small variation of transmission torque characteristics. <P>SOLUTION: In this driving force transmitting device wherein an inner shaft is rotatably journaled to an aluminum housing, the outer clutch plates of a clutch are engaged with an engagement part formed on an inner peripheral face of a cylindrical part of the housing in a state of being axially movable while restricted in their relative rotation, inner clutch plates alternately arranged with the outer clutch plates are engaged with an engagement part formed on an outer peripheral face of the inner shaft in a state of being axially movable while restricted in their rotation, and the outer clutch plates and the inner clutch plates are closely kept into contact with each other to engage and disengage the clutch, the treatment for increasing the surface hardness, is performed on the engagement part formed on the inner peripheral face of the cylindrical part of the housing, engaged with the outer clutch plates of the clutch. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、クラッチで駆動力を伝達する駆動力伝達装置に関するものである。
【０００２】
【従来の技術】
従来、駆動力伝達装置として用いられる電磁式パイロットクラッチ装置は、特許文献１に開示されているように、回転可能に支承されたフロントハウジングのクラッチ収納室内にインナシャフトを回転可能に軸承し、メインクラッチのアウタクラッチプレートおよび該アウタクラッチプレートと交互に配置されたインナクラッチプレートを収納室内でフロントハウジングの円筒部内周面におよびインナシャフトの外周面に夫々回転を規制して軸線方向に移動可能に係合している。パイロットクラッチのアウタクラッチプレートおよびインナクラッチプレートをフロントハウジングの円筒部内周面および第１カム部材に夫々回転を規制して軸線方向に移動可能に係合し、磁性金属製のリヤハウジングをパイロットクラッチを挟んでアーマチュアと対向してフロントハウジングの開口端部に固定している。アーマチュアを吸引してパイロットクラッチを係合させる電磁石をリヤハウジングの後端部に対向して配置し、パイロットクラッチの伝達トルクに基づく第２カム部材と第１カム部材との相対回転によるカム機構の作動により第２カム部材を軸線方向に移動させてメインクラッチをパイロットクラッチの伝達トルクを増幅して圧接し、ハウジングとインナシャフトとの間でトルク伝達している。
【０００３】
このフロントハウジングは電磁石で発生する磁束の漏れを防ぎ、さらには軽量化を図るため、アルミ金属で形成されている。
【０００４】
【特許文献１】
特開平１１−１５３１５６号公報（〔００１９〕〔００２１〕〔００４１〕欄、図１）
【０００５】
【発明が解決しようとする課題】
上記電磁式パイロットクラッチ装置では、メインクラッチおよびパイロットクラッチのアウタクラッチプレートはフロントハウジングの円筒部内周面を相対回転を規制されて軸線方向に移動しインナクラッチプレートと圧接してトルク伝達する。ところが、電磁石の磁束の漏洩防止、軽量化のためにアルミ金属をフロントハウジングに使用し、一方のアウタクラッチプレートには強度を得るために鉄系金属を使用しているので、クラッチを係脱するために鉄系金属製のアウタクラッチプレートが軸線方向の移動を繰り返しているうちにフロントハウジングに形成されたアウタクラッチプレートとの係合部が局部的に磨耗することがある。この様子を図３に示す。図３はフロントハウジング９０とアウタクラッチプレート９１との係合部を示すもので、図３（Ａ）は磨耗前の状態を、図３（Ｂ）は磨耗後の状態をそれぞれ示すものである。フロントハウジングの円筒部内周面のアウタクラッチプレートとの係合部が局部的に磨耗していると、アウタクラッチプレートの軸線方向移動に対して抵抗若しくは引っ掛かりとなり、電磁式パイロットクラッチ装置の伝達トルク特性が変化し、トルクの低下や振動が発生する可能性があった。クラッチプレートが磨耗してアウタクラッチプレートのインナクラッチプレートと圧接するための軸線方向移動量が大きくなると特にこの影響が強くなる。
【０００６】
本発明は、係る従来の不具合を改善するためのもので、アウタクラッチプレートとハウジング（フロントハウジング）との係合部の磨耗を抑えアウタクラッチプレートがスムースに追従可能で、伝達トルク特性変化の少ない耐久性が向上した駆動力伝達装置を提供することを目的とする。
【０００７】
【課題を解決するための手段および作用・効果】
上記の課題を解決するため、請求項１に記載の発明の構成上の特徴は、アルミ製ハウジングにインナシャフトを回転可能に軸承し、前記ハウジングの内周と前記インナシャフト外周との間にクラッチ収納室を形成し、クラッチのアウタクラッチプレートを前記クラッチ収納室内で前記ハウジングの円筒部内周面に形成された係合部に相対回転を規制して軸線方向に移動可能に係合し、該アウタクラッチプレートと交互に配置されたインナクラッチプレートを前記クラッチ収納室内で前記インナシャフトの外周面に形成された係合部に回転を規制して軸線方向に移動可能に係合し、前記アウタクラッチプレートおよびインナクラッチプレートを圧接して前記クラッチを係脱するクラッチ係脱装置を前記クラッチ収納室に設けた駆動力伝達装置において、前記クラッチのアウタクラッチプレートが係合する前記ハウジングの円筒部内周面に形成された係合部に表面硬度を高くする処理を施したことである。
【０００８】
本発明によれば、クラッチ係脱装置がクラッチのアウタクラッチプレートおよびインナクラッチプレートを圧接するとハウジングの円筒部内周面に形成された係合部とアウタクラッチプレートとの係合、両クラッチプレート間の摩擦力およびインナクラッチプレートとインナシャフトの係合部との係合によりハウジングとインナシャフトとの間でトルク伝達される。ハウジングの円筒部内周面の係合部に表面硬度を高くする処理が施されているので、クラッチを係脱するたびにアウタクラッチプレートが軸線方向の移動を繰り返しても、ハウジングのアウタクラッチプレートとの係合部が磨耗することが低減され、クラッチプレートが磨耗して軸線方向にクリアランスが生じても、アウタクラッチプレートがスムースに追従してクリアランスをなくすことができ、駆動力伝達装置の伝達トルク特性変化が少なく耐久性が向上する。
【０００９】
請求項２に係る発明の構成上の特徴は、請求項１において、前記表面硬度を高くする処理として、前記ハウジングの円筒部内周面に形成された係合部をアルマイト処理、高硬度メッキ処理または熱処理することである。ハウジングのアウタクラッチプレートとの係合部をアルマイト処理、高硬度メッキ処理または熱処理によって容易に低コストで表面硬度を高くすることができ、請求項１に係る発明の効果を奏することができる。
【００１０】
請求項３に係る発明の構成上の特徴は、アルミ製ハウジングにインナシャフトを回転可能に軸承し、前記ハウジングの内周と前記インナシャフト外周との間にクラッチ収納室を形成し、クラッチのアウタクラッチプレートを前記クラッチ収納室内で前記ハウジングの円筒部内周面に形成された係合部に相対回転を規制して軸線方向に移動可能に係合し、該アウタクラッチプレートと交互に配置されたインナクラッチプレートを前記クラッチ収納室内で前記インナシャフトの外周面に形成された係合部に回転を規制して軸線方向に移動可能に係合し、前記アウタクラッチプレートおよびインナクラッチプレートを圧接して前記クラッチを係脱するクラッチ係脱装置を前記クラッチ収納室に設けた駆動力伝達装置において、前記ハウジングを高硬度のアルミ合金製としたことである。ハウジングを高硬度のアルミ合金製とすることにより、ハウジングのアウタクラッチプレートとの係合部の磨耗を減少することができ、請求項１に係る発明の効果を奏することができる。
【００１１】
請求項４に係る発明の構成上の特徴は、アルミ製ハウジングにインナシャフトを回転可能に軸承し、前記ハウジングの内周と前記インナシャフト外周との間にクラッチ収納室を形成し、クラッチのアウタクラッチプレートを前記クラッチ収納室内で前記ハウジングの円筒部内周面に形成された係合部に相対回転を規制して軸線方向に移動可能に係合し、該アウタクラッチプレートと交互に配置されたインナクラッチプレートを前記クラッチ収納室内で前記インナシャフトの外周面に形成された係合部に回転を規制して軸線方向に移動可能に係合し、前記アウタクラッチプレートおよびインナクラッチプレートを圧接して前記クラッチを係脱するクラッチ係脱装置を前記クラッチ収納室に設けた駆動力伝達装置において、前記クラッチのアウタクラッチプレートが係合する前記ハウジングの円筒部内周面に形成された係合部に油溜りが多い面性状を確保する処理を施したことである。本発明によれば、ハウジングのアウタクラッチプレートとの係合部に油溜りが多い面性状を確保する処理を施したので、ハウジングのアウタクラッチプレートとの係合部の磨耗を減少することができ、請求項１に係る発明の効果を奏することができる。
【００１２】
請求項５に係る発明の構成上の特徴は、請求項４において、前記油溜りが多い面性状を確保する処理として、前記ハウジングの円筒部内周面に形成された係合部をショットブラスト処理することである。本発明によれば、ハウジングのアウタクラッチプレートとの係合部をショットブラスト処理によって簡単に低コストで油溜りが多い面性状にすることができ、ハウジングの係合部の磨耗を減少して請求項１に係る発明の効果を奏することができる。
【００１３】
請求項６に係る発明の構成上の特徴は、請求項１乃至５のいずれか１項において、アルミ製ハウジングにインナシャフトを回転可能に軸承し、前記ハウジングの内周と前記インナシャフト外周との間にクラッチ収納室を形成し、メインクラッチのメインアウタクラッチプレートを前記クラッチ収納室内で前記ハウジングの円筒部内周面に形成された係合部に相対回転を規制して軸線方向に移動可能に係合し、該アウタクラッチプレートと交互に配置されたインナクラッチプレートを前記クラッチ収納室内で前記インナシャフトの外周面に形成された係合部に回転を規制して軸線方向に移動可能に係合し、パイロットクラッチのパイロットアウタクラッチプレートを前記クラッチ収納室内で前記ハウジングの円筒部内周面に形成された係合部に相対回転を規制して軸線方向に移動可能に係合し、該パイロットアウタクラッチプレートと交互に配置されたパイロットインナクラッチプレートを第１カム部材に相対回転を規制して軸線方向に移動可能に係合し、磁性体の大径および小径リヤハウジング部を非磁性体の環状の中間部材で結合したリヤハウジングを前記パイロットクラッチを挟んでアーマチュアと対向して前記ハウジングの開口端部に固定し、前記アーマチュアを吸引して前記パイロットクラッチを係合させる電磁石を前記大径および小径リヤハウジングの後端部に対向して配置し、前記パイロットクラッチの伝達トルクに基づく第２カム部材と第１カム部材との相対回転によるカム機構の作動により前記第２カム部材を軸線方向に移動して前記メインクラッチを前記パイロットクラッチの伝達トルクを増幅して圧接するカム式増幅機構を備えた電磁式パイロットクラッチ装置におけるハウジングの円筒部内周面に形成された係合部が、前記クラッチのアウタクラッチプレートが係合する前記ハウジングの円筒部内周面に形成された係合部であることである。
【００１４】
本発明によれば、電磁石が励磁されてパイロットクラッチが圧接されて第２カム部材と第１カム部材とが相対回転し、第２カム部材がカム機構により軸線方向に移動してメインクラッチを圧接すると、ハウジングの円筒部内周面に形成された係合部とメインアウタクラッチプレートとの係合、両クラッチプレート間の摩擦力およびメインインナクラッチプレートとインナシャフトの係合部との係合によりハウジングとインナシャフトとの間でトルク伝達される。ハウジングの円筒部内周面に形成された係合部に表面硬度を高くする処理または油溜りが多い面性状を確保する処理を施し、若しくはハウジングを高硬度のアルミ合金製とするので、パイロットクラッチ延いてはメインクラッチを係脱するたびにパイロットアウタクラッチプレートおよびメインアウタクラッチプレートが軸線方向の移動を繰り返しても、ハウジングの両アウタクラッチプレートとの係合部が磨耗することが低減され、パイロットクラッチプレート、メインクラッチプレートが夫々磨耗して軸線方向にクリアランスが生じても、両アウタクラッチプレートが夫々スムースに追従してクリアランスをなくすことができ、駆動力伝達装置の伝達トルク特性変化が少なく耐久性が向上する。
【００１５】
【実施の形態】
以下、本発明の実施形態に係る駆動力伝達装置である電磁式パイロットクラッチ装置１を図１及び図２に基づいて説明する。電磁式パイロットクラッチ１は、例えばエンジンの駆動力を制御して後輪側に伝達するために、プロペラシャフトの途中に介在されている。電磁式パイロットクラッチ装置１の有底円筒状のアルミ製ハウジング３は、図略のクラッチケースに軸受によって回転軸線Ｏ回りに回転可能に支承されている。ハウジング３の開口端部には磁路形成部材であるリヤハウジング５が螺着され、ハウジング３内に密封されたクラッチ収納室６を画成している。ハウジング３の底部に形成された凹部とリヤハウジング５の内周孔にはインナシャフト７の両端部が軸受８，９によって回転軸線Ｏ回りに回転可能に軸承されている。ハウジング３の前端面に前方プロペラシャフトがボルトによって結合され、インナシャフト７の後端に形成されたセレーション穴に後方プロペラシャフトがセレーション嵌合される。
【００１６】
クラッチ収納室６内にはメインクラッチ１２が配設され、メインクラッチ１２は複数のメインアウタクラッチプレート１３及びメインインナクラッチプレート１４を備えている。メインアウタクラッチプレート１３は、クラッチ収納室６内でハウジング３の円筒部内周面に形成された係合部１１（図２参照）にセレーション嵌合し相対回転を規制して軸線方向に移動可能に係合し、メインインナクラッチプレート１４は、クラッチ収納室６内でインナシャフト７の中央部外周面に形成された係合部２５にセレーション嵌合し相対回転を規制して軸線方向に移動可能に係合している。メインアウタクラッチプレート１３とメインインナクラッチプレート１４は交互に配置されており、係合時は互いに当接して摩擦係合し、離脱時は互いに離間して非係合状態となる。
【００１７】
カム式増幅機構１５は、メインクラッチ１２の後方に配設され、第１カム部材１６、第２カム部材１７及び複数のカムフォロア１８とからなっている。第２カム部材１７は、インナシャフト７の係合部２５外周にセレーション嵌合して係合した状態で、一端面がメインクラッチ１２と当接しており、カム機構によりメインクラッチ１２を押圧するようになっている。第１カム部材１６は、複数のカムフォロア１８を挟んで第２カム部材１７の後方でインナシャフト７に遊嵌されており、後述するパイロットクラッチ２０の半径内周側に位置している。複数のカムフォロア１８は、第１、第２カム部材１６，１７の対向面に形成されているカム溝に介装されている。
【００１８】
パイロットクラッチ２０は、パイロットアウタクラッチプレート２１とパイロットインナクラッチプレート２２とからなり、第２カム部材１７の後方に配置され、パイロットアウタクラッチプレート２１は、クラッチ収納室６内でハウジング３の円筒部内周面に形成された係合部１１にセレーション嵌合し相対回転を規制して軸線方向に移動可能に係合し、パイロットインナクラッチプレート２２は、第１カム部材１６の外周面にセレーション嵌合し相対回転を規制して軸線方向に移動可能に係合している。アーマチャ２３は環状をなし、パイロットクラッチ２０と第２カム部材１７との間に配置され、クラッチ収納室６内周面にセレーション嵌合し相対回転を規制して軸線方向に移動可能に係合している。アーマチャ２３は、後述する電磁石２４を基点として形成される磁束により吸引されて、パイロットクラッチ２０を圧接するようになっている。ハウジング３は電磁石２４からリヤハウジング５、アーマチャ２３を循環される磁束の漏洩防止、軽量化のために非磁性金属のアルミ材が使用されている。
【００１９】
ハウジング３の円筒部内周面に形成された係合部１１にはアルマイト処理などの表面硬度を高くする処理が施されている。係合部１１をアルマイト処理することにより、アルミ材の高度（Ｈｖ１００程度）がＨｖ５００〜８００程度に高められる。これにより、クラッチ（メインクラッチ１２およびパイロットクラッチ２０）を係脱するたびに鉄系金属で形成されたアウタクラッチプレート（メインアウタクラッチプレート１３およびパイロットアウタクラッチプレート２１）が軸線方向の移動を繰り返しても、ハウジング３のアウタクラッチプレートとの係合部１１が磨耗することが低減され、クラッチ１２，２０のクラッチプレートが磨耗して軸線方向にクリアランスが生じても、アウタクラッチプレート１３，２１がスムースに追従してクリアランスをなくし、十分な伝達トルク特性を確保すことができる。
【００２０】
ハウジング３の円筒部内周面に形成された係合部１１の表面硬度を高くするために、係合部１１にニッケルクロム合金のメッキ処理を施してもよい。また、係合部１１にＴ６処理のような熱処理を施してもよく、係合部１１にハイス等の微小硬球を高圧で吹き付けるショットブラスト処理を施してもよい。
【００２１】
パイロットクラッチ２０の後方には、ハウジング３の開口端部を覆うリヤハウジング５が固着されている。リヤハウジング５は、鉄等の磁性金属製の大径リヤハウジング部２６および小径リヤハウジング部２７並びにステンレス等の非磁性金属製の中間部材２８から形成されている。大径リヤハウジング部２６の前端部および小径リヤハウジング部２７の前端部の間に環状の中間部材２８が介在され、大径及び小径リヤハウジング部２６，２７が中間部材２８に前端部で溶接によって一体に結合されている。大径リヤハウジング部２６がハウジング３の開口端部内周面に螺合され、リヤハウジング５がメインクラッチ１２を予圧接した状態でハウジング３に固定されている。大径リヤハウジング部２６の内周には、所定間隔を保って小径リヤハウジング部２７が配置され、小径リヤハウジング部２７は段付き筒形状で、インナシャフト７の端部をニードルベアリング９によって回転可能に支承している。
【００２２】
リヤハウジング５の先端面に形成されたクラッチ当接面３１とアーマチュア２３との間にパイロットクラッチ２０が介在され、端子を介して通電される環状の電磁石２４が大径及び小径リヤハウジング部２６，２７および中間部材２８に囲まれた位置でヨーク３２に固着されている。ヨーク３２は大径および小径リヤハウジング部２６，２７と微小隙間を保ってインナシャフト７に軸受３３によって回転可能に支承され、クラッチケースの後端面に突設されたピンに係合して回り止めされている。
【００２３】
次に、上記のように構成した電磁パイロット式クラッチ装置１の作動について説明する。エンジンを始動すると、エンジンの駆動力が、前方プロペラシャフトによってハウジング３に伝達されハウジング３が回転駆動される。エンジンの始動時は、通常、電磁石２４は非通電状態にあるので磁束は形成されず、パイロットクラッチ２０は非係合状態にあり、第２カム部材１７に押圧力が作用せず、メインアウタクラッチプレート１３とメインインナクラッチプレート１４とは圧接されない状態であり、メインアウタクラッチプレート１３とメインインナクラッチプレート１４とが相対回転し、ハウジング３からインナシャフト７に駆動力は伝達されない。
【００２４】
電磁石２４への通電がなされると、電磁石２４を基点として磁束が形成され、該磁束は小径リヤハウジング部２７、パイロットクラッチ２０、アーマチャ２３、大径リヤハウジング部２６を循環して電磁石２４に帰還し、アーマチャ２３を吸引してパイロットクラッチ２０をリヤハウジング５のクラッチ当接面３１に圧接して摩擦係合するので、カム式増幅機構１５の第１カム部材１６と第２カム部材１７との間に相対回転が生じ、カムフォロア１８とカム溝の作用により、第２カム部材１７が、メインクラッチ１２のメインアウタクラッチプレート１３とメインインナクラッチプレート１４とを圧接する方向に移動し、メインクラッチ１２にパイロットクラッチ２０の摩擦係合力を増幅した伝達トルクが発生する。伝達トルクはインナシャフト７から後方プロペラシャフトに伝達され、デファレンシャル装置を介して自動車の後輪に伝達される。
【００２５】
電磁石２４への通電が繰返され、アーマチャ２３が電磁石２４に吸引されてパイロットクラッチ２０がリヤハウジング５のクラッチ当接面３１に圧接され、メインクラッチ１２がカム式増幅機構１５によって圧接されて、アウタクラッチプレート１３，２１が軸線方向の移動を繰返しても、ハウジング３のアウタクラッチプレート１３，２１との係合部１１の硬度が上げられているので、ハウジング３の係合部１１の磨耗が低減される。これにより、クラッチ１２，２０のクラッチプレートが磨耗して軸線方向にクリアランスが生じても、アウタクラッチプレート１３，２１がスムースに追従してクリアランスをなくすことができ、駆動力伝達装置の伝達トルク特性変化が少なくなり耐久性が向上する。
【００２６】
上記実施形態では、ハウジング３の円筒内周面に形成されたアウタクラッチプレートとの係合部１１に表面硬度を高くする処理を施しているが、ハウジング３を例えばＣｕ、Ｓｉを１％程度含有する硬度の高いアルミ合金で形成し、係合部１１の硬度を高くするようにしてもよい。
【００２７】
上記実施形態では、ハウジング３の係合部１１に表面硬度を高くする処理を施しているが、ハウジング３の円筒部内周面に形成された係合部１１に、ショット処理などの油溜りが多い面性状を確保する処理を施してもよい。これによっても、クラッチ１２，２０を係脱するたびに鉄系金属で形成されたアウタクラッチプレート１３，２１が軸線方向の移動を繰り返しても、ハウジング３のアウタクラッチプレート１３，２１との係合部１１が磨耗することが低減され、クラッチ１２，２０のクラッチプレートが磨耗して軸線方向にクリアランスが生じても、アウタクラッチプレート１３，２１がスムースに追従してクリアランスをなくすことができる。ショット処理は、硬度が低い角のある微小粒体を係合部１１に低圧で吹き付けて係合部１１の表面を粗くして油溜りを形成する。
【００２８】
なお、本明細書において、クラッチとはメインクラッチおよびパイロットクラッチを総称し、アウタクラッチプレートとはメインアウタクラッチプレートおよびパイロットアウタクラッチプレートを総称するものである。
【図面の簡単な説明】
【図１】本発明の実施形態に係る電磁クラッチの縦断面図。
【図２】ハウジングの係合部を示す拡大断面図。
【図３】従来のハウジングの係合部を示す拡大断面図。
【符号の説明】
１…電磁式パイロットクラッチ装置、３…ハウジング、５…リヤハウジング、６…クラッチ収納室、７…インナシャフト、１１…係合部、１２…メインクラッチ、１３…メインアウタクラッチプレート、１４…メインインナクラッチプレート、１５…カム式増幅機構、１６…第１カム部材、１７…第２カム部材、１８…カムフォロア、２０…パイロットクラッチ、２１…パイロットアウタクラッチプレート、２２…パイロットインナクラッチプレート、２３…アーマチャ、２４…電磁石、２５…係合部、２６…大径リヤハウジング部、２７…小径リヤハウジング部、２８…中間部材、３１…クラッチ当接面。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a driving force transmission device that transmits driving force by a clutch.
[0002]
[Prior art]
Conventionally, as disclosed in Patent Document 1, an electromagnetic pilot clutch device used as a driving force transmitting device rotatably supports an inner shaft in a clutch housing chamber of a front housing rotatably supported, The outer clutch plate of the clutch and the inner clutch plate alternately arranged with the outer clutch plate can be axially moved by regulating the rotation on the inner peripheral surface of the cylindrical portion of the front housing and on the outer peripheral surface of the inner shaft in the storage chamber. Is engaged. The outer clutch plate and the inner clutch plate of the pilot clutch are engaged with the inner peripheral surface of the cylindrical portion of the front housing and the first cam member movably in the axial direction by restricting the rotation thereof, respectively, and the rear housing made of magnetic metal is connected to the pilot clutch. The armature is fixed to the open end of the front housing, facing the armature. An electromagnet that attracts the armature and engages the pilot clutch is disposed opposite to the rear end of the rear housing, and the cam mechanism is driven by the relative rotation of the second cam member and the first cam member based on the transmission torque of the pilot clutch. The operation causes the second cam member to move in the axial direction to amplify the transmission torque of the pilot clutch and press-contact the main clutch, thereby transmitting torque between the housing and the inner shaft.
[0003]
The front housing is made of aluminum metal to prevent leakage of magnetic flux generated by the electromagnet and to reduce the weight.
[0004]
[Patent Document 1]
JP-A-11-153156 ([0019] [0021] [0041] column, FIG. 1)
[0005]
[Problems to be solved by the invention]
In the above-mentioned electromagnetic pilot clutch device, the outer clutch plates of the main clutch and the pilot clutch move in the axial direction while the relative rotation of the inner peripheral surface of the cylindrical portion of the front housing is restricted, and the torque is transmitted by pressing against the inner clutch plate. However, aluminum metal is used for the front housing to prevent the leakage of the magnetic flux of the electromagnet and to reduce the weight, and one outer clutch plate is made of iron-based metal to obtain strength, so the clutch is disengaged. Therefore, while the outer clutch plate made of a ferrous metal repeatedly moves in the axial direction, the engagement portion of the front housing formed with the outer clutch plate may be locally worn. This is shown in FIG. 3A and 3B show an engagement portion between the front housing 90 and the outer clutch plate 91. FIG. 3A shows a state before wear, and FIG. 3B shows a state after wear. If the engagement portion of the inner peripheral surface of the cylindrical portion of the front housing with the outer clutch plate is locally worn, the outer clutch plate resists or catches the axial movement of the outer clutch plate, and the transmission torque characteristic of the electromagnetic pilot clutch device. , And there is a possibility that torque may be reduced or vibration may occur. This effect is particularly pronounced when the clutch plate is worn and the amount of axial movement of the outer clutch plate for pressing against the inner clutch plate is increased.
[0006]
SUMMARY OF THE INVENTION The present invention is intended to solve such a conventional problem, and suppresses wear of an engagement portion between an outer clutch plate and a housing (a front housing) so that the outer clutch plate can smoothly follow the transmission torque and a change in transmission torque characteristics is small. An object is to provide a driving force transmission device with improved durability.
[0007]
[Means for Solving the Problems and Functions / Effects]
In order to solve the above-mentioned problem, a structural feature of the invention described in claim 1 is that an inner shaft is rotatably supported on an aluminum housing, and a clutch is provided between an inner periphery of the housing and an outer periphery of the inner shaft. A storage chamber is formed, and the outer clutch plate of the clutch is engaged with an engagement portion formed on the inner peripheral surface of the cylindrical portion of the housing in the clutch storage chamber so as to restrict relative rotation and movably engage in the axial direction. An inner clutch plate alternately disposed with a clutch plate is engaged with an engagement portion formed on an outer peripheral surface of the inner shaft in the clutch storage chamber so as to restrict rotation and axially movably engage the outer clutch plate. And a clutch engaging / disengaging device for engaging and disengaging the clutch by pressing the inner clutch plate against the driving force transmitting device provided in the clutch storage chamber. There are, outer clutch plates of the clutch is that which has been subjected to treatment to increase the surface hardness to the engaging portion formed in the cylindrical inner peripheral surface of the housing to be engaged.
[0008]
According to the present invention, when the clutch engagement / disengagement device presses the outer clutch plate and the inner clutch plate of the clutch, the engagement between the engagement portion formed on the inner peripheral surface of the cylindrical portion of the housing and the outer clutch plate, the engagement between the two clutch plates. Torque is transmitted between the housing and the inner shaft by the frictional force and the engagement between the inner clutch plate and the engagement portion of the inner shaft. Since the surface of the engagement portion on the inner peripheral surface of the cylindrical portion of the housing is treated to increase the surface hardness, even if the outer clutch plate repeatedly moves in the axial direction every time the clutch is disengaged, the outer clutch plate of the housing and The outer clutch plate can smoothly follow the clearance and eliminate the clearance even if the clutch plate is worn and the clearance is generated in the axial direction, and the transmission torque of the driving force transmission device is reduced. There is little characteristic change and durability is improved.
[0009]
According to a second aspect of the present invention, in the first aspect, as the process for increasing the surface hardness, the engaging portion formed on the inner peripheral surface of the cylindrical portion of the housing is subjected to alumite treatment, high hardness plating treatment, or the like. Heat treatment. The surface hardness of the engagement portion of the housing with the outer clutch plate can be easily increased at low cost by alumite treatment, high hardness plating treatment or heat treatment, and the effect of the invention according to claim 1 can be achieved.
[0010]
The structural feature of the invention according to claim 3 is that an inner shaft is rotatably supported on an aluminum housing, and a clutch storage chamber is formed between an inner periphery of the housing and an outer periphery of the inner shaft. The clutch plate is engaged with an engagement portion formed on the inner peripheral surface of the cylindrical portion of the housing in the clutch storage chamber so that the clutch plate is movably engaged in the axial direction by restricting relative rotation, and the inner plate is alternately arranged with the outer clutch plate. The clutch plate restricts rotation and engages movably in the axial direction in an engagement portion formed on the outer peripheral surface of the inner shaft in the clutch storage chamber, and presses the outer clutch plate and the inner clutch plate to press-contact with each other. In a driving force transmission device in which a clutch disengaging device for disengaging a clutch is provided in the clutch storage chamber, the housing may be hardened. It is made of aluminum alloy and was it. By forming the housing from a high-hardness aluminum alloy, it is possible to reduce the wear of the engaging portion of the housing with the outer clutch plate, and the effect of the invention according to claim 1 can be obtained.
[0011]
A structural feature of the invention according to claim 4 is that an inner shaft is rotatably supported on an aluminum housing, and a clutch storage chamber is formed between an inner periphery of the housing and an outer periphery of the inner shaft. The clutch plate is engaged with an engagement portion formed on the inner peripheral surface of the cylindrical portion of the housing in the clutch storage chamber so that the clutch plate is movably engaged in the axial direction by restricting relative rotation, and the inner plate is alternately arranged with the outer clutch plate. The clutch plate restricts rotation and engages movably in the axial direction in an engagement portion formed on the outer peripheral surface of the inner shaft in the clutch storage chamber, and presses the outer clutch plate and the inner clutch plate to press-contact with each other. In a driving force transmission device provided with a clutch disengagement device for disengaging a clutch in the clutch storage chamber, the clutch outer Latch plate is that which has been subjected to processing to ensure the oil reservoir often face property to the engaging portion formed in the cylindrical inner peripheral surface of the housing to be engaged. According to the present invention, since a process of securing a surface property with a large amount of oil pool is performed on the engagement portion of the housing with the outer clutch plate, wear of the engagement portion of the housing with the outer clutch plate can be reduced. Thus, the effects of the invention according to claim 1 can be obtained.
[0012]
According to a fifth aspect of the present invention, as described in the fourth aspect, as the process for securing the surface property with a large amount of oil pool, the engaging portion formed on the inner peripheral surface of the cylindrical portion of the housing is shot blasted. That is. ADVANTAGE OF THE INVENTION According to this invention, the engagement part with the outer clutch plate of a housing can be easily made into the surface property with many oil sumps by shot blast processing at low cost, and the wear of the engagement part of a housing is reduced. The effects of the invention according to Item 1 can be obtained.
[0013]
A structural feature of the invention according to claim 6 is that, in any one of claims 1 to 5, the inner shaft is rotatably supported on an aluminum housing, and an inner periphery of the housing and an outer periphery of the inner shaft are connected to each other. A clutch storage chamber is formed between the clutch storage chambers, and the main outer clutch plate of the main clutch is engaged with an engagement portion formed on the inner peripheral surface of the cylindrical portion of the housing in the clutch storage chamber so as to be able to move in the axial direction by restricting relative rotation. The inner clutch plates alternately arranged with the outer clutch plates are engaged with the engaging portions formed on the outer peripheral surface of the inner shaft in the clutch storage chamber so as to restrict rotation and move movably in the axial direction. The pilot outer clutch plate of the pilot clutch is engaged with the engagement portion formed on the inner peripheral surface of the cylindrical portion of the housing in the clutch storage chamber. The pilot inner clutch plate alternately arranged with the pilot outer clutch plate is engaged with the first cam member so as to be movable relative to the first cam member so as to be movable in the axial direction. A rear housing in which the large-diameter and small-diameter rear housing portions of the magnetic material are joined by an annular intermediate member of a non-magnetic material is fixed to the open end of the housing, facing the armature with the pilot clutch interposed therebetween, An electromagnet that attracts an armature and engages the pilot clutch is disposed opposite to the rear ends of the large-diameter and small-diameter rear housings, and a second cam member and a first cam member based on the transmission torque of the pilot clutch. The second cam member is moved in the axial direction by the operation of the cam mechanism by the relative rotation of An engaging portion formed on an inner peripheral surface of a cylindrical portion of a housing in an electromagnetic pilot clutch device having a cam type amplifying mechanism that amplifies a transmission torque of a clutch and press-contacts the housing, the housing engaging an outer clutch plate of the clutch. Is an engaging portion formed on the inner peripheral surface of the cylindrical portion.
[0014]
According to the present invention, the electromagnet is excited, the pilot clutch is pressed and the second cam member and the first cam member rotate relative to each other, and the second cam member moves in the axial direction by the cam mechanism to press the main clutch. Then, the engagement between the engagement portion formed on the inner peripheral surface of the cylindrical portion of the housing and the main outer clutch plate, the frictional force between the two clutch plates, and the engagement between the engagement portion between the main inner clutch plate and the inner shaft are performed. Is transmitted between the shaft and the inner shaft. The engaging portion formed on the inner peripheral surface of the cylindrical portion of the housing is subjected to a process of increasing the surface hardness or a process of securing a surface property with a large amount of oil accumulation, or the housing is made of a high-hardness aluminum alloy. Therefore, even if the pilot outer clutch plate and the main outer clutch plate repeatedly move in the axial direction each time the main clutch is disengaged, wear of the engagement portion of the housing with both outer clutch plates is reduced, and the pilot clutch is reduced. Even if the plate and the main clutch plate are worn away and a clearance is created in the axial direction, both outer clutch plates follow each other smoothly and the clearance can be eliminated. Is improved.
[0015]
Embodiment
Hereinafter, an electromagnetic pilot clutch device 1 which is a driving force transmission device according to an embodiment of the present invention will be described with reference to FIGS. The electromagnetic pilot clutch 1 is interposed in the middle of the propeller shaft, for example, in order to control the driving force of the engine and transmit it to the rear wheels. The bottomed cylindrical aluminum housing 3 of the electromagnetic pilot clutch device 1 is rotatably supported around a rotation axis O by a bearing in a clutch case (not shown). A rear housing 5, which is a magnetic path forming member, is screwed to an open end of the housing 3 to define a clutch storage chamber 6 sealed inside the housing 3. Both ends of the inner shaft 7 are rotatably supported by bearings 8 and 9 so as to be rotatable around a rotation axis O in a recess formed in the bottom of the housing 3 and an inner peripheral hole of the rear housing 5. A front propeller shaft is connected to a front end surface of the housing 3 by bolts, and a rear propeller shaft is serrated into a serration hole formed at a rear end of the inner shaft 7.
[0016]
A main clutch 12 is provided in the clutch storage chamber 6, and the main clutch 12 includes a plurality of main outer clutch plates 13 and a main inner clutch plate 14. The main outer clutch plate 13 is serrated to engage with an engagement portion 11 (see FIG. 2) formed on the inner peripheral surface of the cylindrical portion of the housing 3 in the clutch storage chamber 6 to regulate relative rotation and move in the axial direction. The main inner clutch plate 14 is engaged with the engagement portion 25 formed on the outer peripheral surface of the central portion of the inner shaft 7 in the clutch storage chamber 6 to regulate the relative rotation and move in the axial direction. Is engaged. The main outer clutch plates 13 and the main inner clutch plates 14 are alternately arranged. When engaged, the main outer clutch plates 13 and the main inner clutch plates 14 come into contact with each other and frictionally engage with each other.
[0017]
The cam type amplification mechanism 15 is disposed behind the main clutch 12 and includes a first cam member 16, a second cam member 17, and a plurality of cam followers 18. One end surface of the second cam member 17 is in contact with the main clutch 12 in a state where the second cam member 17 is serrated and engaged with the outer periphery of the engagement portion 25 of the inner shaft 7, and the main mechanism 12 is pressed by the cam mechanism. It has become. The first cam member 16 is loosely fitted to the inner shaft 7 behind the second cam member 17 with a plurality of cam followers 18 interposed therebetween, and is located on the radial inner side of a pilot clutch 20 described later. The plurality of cam followers 18 are interposed in cam grooves formed on the opposing surfaces of the first and second cam members 16 and 17.
[0018]
The pilot clutch 20 includes a pilot outer clutch plate 21 and a pilot inner clutch plate 22. The pilot clutch 20 is disposed behind the second cam member 17. The pilot inner clutch plate 22 is serrated on the outer peripheral surface of the first cam member 16 by serration-fitting the engagement portion 11 formed on the surface to regulate relative rotation and movably engage in the axial direction. It is engaged so as to be movable in the axial direction while restricting relative rotation. The armature 23 has an annular shape and is disposed between the pilot clutch 20 and the second cam member 17. The armature 23 is serrated on the inner peripheral surface of the clutch storage chamber 6 to regulate relative rotation and engage movably in the axial direction. ing. The armature 23 is attracted by a magnetic flux formed with an electromagnet 24 described later as a base point, and presses the pilot clutch 20 in pressure. The housing 3 is made of a non-magnetic metal aluminum material to prevent leakage of magnetic flux circulated from the electromagnet 24 through the rear housing 5 and the armature 23 and to reduce the weight.
[0019]
The engaging portion 11 formed on the inner peripheral surface of the cylindrical portion of the housing 3 is subjected to a process of increasing surface hardness such as an alumite process. By performing the alumite treatment on the engaging portion 11, the height (about Hv100) of the aluminum material is increased to about Hv500 to 800. Thus, each time the clutch (main clutch 12 and pilot clutch 20) is disengaged, the outer clutch plate (main outer clutch plate 13 and pilot outer clutch plate 21) formed of an iron-based metal repeatedly moves in the axial direction. In addition, the wear of the engaging portion 11 of the housing 3 with the outer clutch plate is reduced, and even if the clutch plates of the clutches 12 and 20 are worn and clearance is generated in the axial direction, the outer clutch plates 13 and 21 can be smoothed. , Clearance can be eliminated, and sufficient transmission torque characteristics can be secured.
[0020]
In order to increase the surface hardness of the engaging portion 11 formed on the inner peripheral surface of the cylindrical portion of the housing 3, the engaging portion 11 may be subjected to a nickel-chromium alloy plating process. Further, a heat treatment such as a T6 treatment may be applied to the engaging portion 11, or a shot blasting process in which microhard balls such as high-speed steel are blown at a high pressure may be applied to the engaging portion 11.
[0021]
A rear housing 5 that covers the open end of the housing 3 is fixed behind the pilot clutch 20. The rear housing 5 includes a large-diameter rear housing portion 26 and a small-diameter rear housing portion 27 made of a magnetic metal such as iron, and an intermediate member 28 made of a non-magnetic metal such as stainless steel. An annular intermediate member 28 is interposed between the front end of the large-diameter rear housing portion 26 and the front end of the small-diameter rear housing portion 27, and the large-diameter and small-diameter rear housing portions 26, 27 are welded to the intermediate member 28 at the front ends. They are joined together. A large-diameter rear housing portion 26 is screwed to the inner peripheral surface of the opening end of the housing 3, and the rear housing 5 is fixed to the housing 3 in a state where the main clutch 12 is pre-pressed. A small-diameter rear housing portion 27 is arranged at an inner periphery of the large-diameter rear housing portion 26 at a predetermined interval, and the small-diameter rear housing portion 27 has a stepped cylindrical shape, and the end of the inner shaft 7 is rotated by the needle bearing 9. We support as much as possible.
[0022]
A pilot clutch 20 is interposed between a clutch contact surface 31 formed on the distal end surface of the rear housing 5 and the armature 23, and annular electromagnets 24, which are energized via terminals, have large-diameter and small-diameter rear housing parts 26, It is fixed to the yoke 32 at a position surrounded by the intermediate member 27 and the intermediate member 28. The yoke 32 is rotatably supported on the inner shaft 7 by a bearing 33 while maintaining a small gap with the large-diameter and small-diameter rear housing portions 26 and 27, and engages with a pin protruding from the rear end surface of the clutch case to prevent rotation. Have been.
[0023]
Next, the operation of the electromagnetic pilot type clutch device 1 configured as described above will be described. When the engine is started, the driving force of the engine is transmitted to the housing 3 by the front propeller shaft, and the housing 3 is driven to rotate. When the engine is started, normally, the electromagnet 24 is in the non-energized state, so that no magnetic flux is formed, the pilot clutch 20 is in the non-engaged state, no pressing force acts on the second cam member 17, and the main outer clutch The plate 13 and the main inner clutch plate 14 are not pressed against each other, the main outer clutch plate 13 and the main inner clutch plate 14 rotate relative to each other, and no driving force is transmitted from the housing 3 to the inner shaft 7.
[0024]
When the electromagnet 24 is energized, a magnetic flux is formed starting from the electromagnet 24, and the magnetic flux circulates through the small-diameter rear housing 27, the pilot clutch 20, the armature 23, and the large-diameter rear housing 26 and returns to the electromagnet 24. Then, the armature 23 is sucked and the pilot clutch 20 is brought into pressure contact with the clutch contact surface 31 of the rear housing 5 and frictionally engaged with the clutch, so that the first cam member 16 and the second cam member 17 of the cam type amplification mechanism 15 A relative rotation is generated between the main clutch 12 and the second cam member 17 in the direction of pressing the main outer clutch plate 13 and the main inner clutch plate 14 of the main clutch 12 by the action of the cam follower 18 and the cam groove. Then, a transmission torque that amplifies the frictional engagement force of pilot clutch 20 is generated. The transmission torque is transmitted from the inner shaft 7 to the rear propeller shaft, and transmitted to the rear wheels of the automobile via a differential device.
[0025]
The energization of the electromagnet 24 is repeated, the armature 23 is attracted to the electromagnet 24, the pilot clutch 20 is pressed against the clutch contact surface 31 of the rear housing 5, the main clutch 12 is pressed against the cam type amplifying mechanism 15, and the outer clutch is pressed. Even when the clutch plates 13 and 21 repeatedly move in the axial direction, the hardness of the engagement portions 11 of the housing 3 with the outer clutch plates 13 and 21 is increased, so that the wear of the engagement portions 11 of the housing 3 is reduced. Is done. As a result, even if the clutch plates of the clutches 12 and 20 are worn and a clearance is generated in the axial direction, the outer clutch plates 13 and 21 can smoothly follow the clearance and eliminate the clearance, and the transmission torque characteristic of the driving force transmission device can be reduced. Change is reduced and durability is improved.
[0026]
In the above-described embodiment, the surface of the engaging portion 11 formed on the inner peripheral surface of the cylindrical portion of the housing 3 with the outer clutch plate is treated to increase the surface hardness. However, the housing 3 contains, for example, about 1% of Cu and Si. Alternatively, the engagement portion 11 may be formed of an aluminum alloy having high hardness.
[0027]
In the above embodiment, the engaging portion 11 of the housing 3 is subjected to a process of increasing the surface hardness, but the engaging portion 11 formed on the inner peripheral surface of the cylindrical portion of the housing 3 has a large amount of oil pool such as a shot process. A process for ensuring surface properties may be performed. Even if the outer clutch plates 13 and 21 made of a ferrous metal repeatedly move in the axial direction each time the clutches 12 and 20 are disengaged, the engagement of the housing 3 with the outer clutch plates 13 and 21 can be achieved. The wear of the portion 11 is reduced, and even if the clutch plates of the clutches 12 and 20 are worn and a clearance is generated in the axial direction, the outer clutch plates 13 and 21 can smoothly follow the clearance and eliminate the clearance. In the shot process, fine particles having corners having a low hardness are sprayed on the engaging portion 11 at a low pressure to roughen the surface of the engaging portion 11 to form an oil reservoir.
[0028]
In this specification, the term clutch generally refers to a main clutch and a pilot clutch, and the term outer clutch plate refers to a main outer clutch plate and a pilot outer clutch plate.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an electromagnetic clutch according to an embodiment of the present invention.
FIG. 2 is an enlarged sectional view showing an engagement portion of a housing.
FIG. 3 is an enlarged sectional view showing an engaging portion of a conventional housing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electromagnetic pilot clutch device, 3 ... Housing, 5 ... Rear housing, 6 ... Clutch storage room, 7 ... Inner shaft, 11 ... Engagement part, 12 ... Main clutch, 13 ... Main outer clutch plate, 14 ... Main inner Clutch plate, 15: Cam type amplifying mechanism, 16: First cam member, 17: Second cam member, 18: Cam follower, 20: Pilot clutch, 21: Pilot outer clutch plate, 22: Pilot inner clutch plate, 23: Armature , 24 ... electromagnet, 25 ... engaging part, 26 ... large diameter rear housing part, 27 ... small diameter rear housing part, 28 ... intermediate member, 31 ... clutch contact surface.

Claims

An inner shaft is rotatably supported on an aluminum housing, a clutch storage chamber is formed between an inner periphery of the housing and an outer periphery of the inner shaft, and an outer clutch plate of a clutch is disposed in a cylindrical portion of the housing in the clutch storage chamber. The inner clutch plates alternately arranged with the outer clutch plates are engaged with the engagement portions formed on the peripheral surface such that the inner clutch plates are movably engaged in the axial direction while restricting the relative rotation. A clutch engaging / disengaging device for engaging the outer clutch plate and the inner clutch plate to engage and disengage the clutch by restricting the rotation to the engaging portion formed on the surface and movably engaging the engaging portion with the outer clutch plate and the inner clutch plate. In the driving force transmission device provided in the chamber, the housing in which an outer clutch plate of the clutch is engaged. Grayed driving force transmission apparatus is characterized in that subjected to a treatment to increase the surface hardness to the engaging portion formed on the peripheral surface the cylindrical portion of the.

2. The method for increasing the surface hardness according to claim 1, wherein at least one of alumite processing, high hardness plating processing, heat treatment, and shot processing is performed on the engaging portion formed on the inner peripheral surface of the cylindrical portion of the housing. A driving force transmission device characterized by the above-mentioned.

An inner shaft is rotatably supported on an aluminum housing, a clutch storage chamber is formed between an inner periphery of the housing and an outer periphery of the inner shaft, and an outer clutch plate of a clutch is disposed in a cylindrical portion of the housing in the clutch storage chamber. The inner clutch plates alternately arranged with the outer clutch plates are engaged with the engagement portions formed on the peripheral surface such that the inner clutch plates are movably engaged in the axial direction while restricting the relative rotation. A clutch engaging / disengaging device for engaging the outer clutch plate and the inner clutch plate to engage and disengage the clutch by restricting the rotation to the engaging portion formed on the surface and movably engaging the engaging portion with the outer clutch plate and the inner clutch plate. In the driving force transmission device provided in the chamber, the housing is made of a high-hardness aluminum alloy. Driving force transmitting device.

An inner shaft is rotatably supported on an aluminum housing, a clutch storage chamber is formed between an inner periphery of the housing and an outer periphery of the inner shaft, and an outer clutch plate of a clutch is disposed in a cylindrical portion of the housing in the clutch storage chamber. The inner clutch plates alternately arranged with the outer clutch plates are engaged with the engagement portions formed on the peripheral surface such that the inner clutch plates are movably engaged in the axial direction while restricting the relative rotation. A clutch engaging / disengaging device for engaging the outer clutch plate and the inner clutch plate to engage and disengage the clutch by restricting the rotation to the engaging portion formed on the surface and movably engaging the engaging portion with the outer clutch plate and the inner clutch plate. In the driving force transmission device provided in the chamber, the housing in which an outer clutch plate of the clutch is engaged. Grayed driving force transmission apparatus is characterized in that applied to the engaging portion formed on the peripheral surface the cylindrical portion a process to ensure the oil reservoir often face property of.

5. The driving force transmission device according to claim 4, wherein, as the process for securing the surface property with a large amount of oil sump, an engaging portion formed on an inner peripheral surface of the cylindrical portion of the housing is shot blasted.

The inner clutch according to any one of claims 1 to 5, wherein the inner shaft is rotatably supported on an aluminum housing, and a clutch storage chamber is formed between an inner periphery of the housing and an outer periphery of the inner shaft. The outer clutch plate is engaged with the engaging portion formed on the inner peripheral surface of the cylindrical portion of the housing in the clutch accommodating chamber so as to restrict relative rotation and movably engage in the axial direction, and is alternately arranged with the outer clutch plate. The inner clutch plate is rotatably engaged with an engagement portion formed on the outer peripheral surface of the inner shaft in the clutch storage chamber so as to restrict rotation and move a pilot outer clutch plate of a pilot clutch in the clutch storage chamber. It is possible to move in the axial direction by restricting the relative rotation to the engaging part formed on the inner peripheral surface of the cylindrical part of the housing. A large-diameter and small-diameter rear housing made of a magnetic material, wherein the pilot inner clutch plate alternately arranged with the pilot outer clutch plate is engaged with the first cam member so as to be movable in the axial direction while restricting relative rotation. A rear housing whose parts are joined by a ring-shaped intermediate member of a non-magnetic material is fixed to an open end of the housing facing the armature with the pilot clutch interposed therebetween, and the armature is sucked to engage the pilot clutch. An electromagnet is disposed opposite to the rear ends of the large-diameter and small-diameter rear housings, and the second cam member is operated by the relative rotation of the second cam member and the first cam member based on the transmission torque of the pilot clutch. By moving the cam member in the axial direction, the main clutch amplifies the transmission torque of the pilot clutch to increase the pressure. The engaging portion formed on the inner peripheral surface of the cylindrical portion of the housing in the electromagnetic pilot clutch device having the cam-type amplifying mechanism is formed on the inner peripheral surface of the cylindrical portion of the housing with which the outer clutch plate of the clutch engages. A driving force transmission device, which is an engagement portion.