JP2004248980A

JP2004248980A - Chair

Info

Publication number: JP2004248980A
Application number: JP2003044655A
Authority: JP
Inventors: Tomokazu Murakami; 智一村上
Original assignee: Kokuyo Co Ltd
Current assignee: Kokuyo Co Ltd
Priority date: 2003-02-21
Filing date: 2003-02-21
Publication date: 2004-09-09
Anticipated expiration: 2023-02-21
Also published as: JP4133427B2

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems of a chair with a tilting mechanism wherein a large power is required for backward tilting a backrest largely, the backrest can not be backward tilted largely without using muscular strength in addition to the body weight, and a short person or a light-weight woman can not take the reclining posture satisfactorily. <P>SOLUTION: In the chair, a coil spring SP is compressed when a backrest arm 31 is tilted backward. As the backrest arm 31 is tilted backward, the direction of compressing the coil spring SP gradually varies relatively to the tangential direction for the part where the spring force works on the backrest arm 31 to rotate. Since the direction of the whole reaction force F1 of the coil spring SP is gradually shifted, the size of the effective component Fy of the reaction force for the coil spring SP to return the backrest arm 31 to the upright posture can be appropriately controlled by setting the degree of compression of the coil spring SP and the way of shifting of the direction at the time of the backward tilting of the backrest arm 31. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、背凭れを傾動させることができるチルト機構を有した椅子に関する。
【０００２】
【従来の技術】
従来、背座シンクロチルトや背のみのチルトなどを含め種々の背凭れチルト機構を有した椅子が開発されているが、代表的には、特許文献１に示されるように、脚等を取り付けるベース部材と、このベース部材に基端部を回動可能に支持させた背凭れアームを具備した上で、背座シンクロチルトの場合は、前記ベース部材に前端部をスライドかつ回転可能に支持させ、後端部を背凭れアームの基端部近傍に回転可能に支持させた座と、座の下部に傾動に伴って相対距離の変化する２点間に介在するように接続されたバネを有し、背のみのチルトの場合は、背凭れアームの基端部近傍で座の下部や、背凭れアームの基端部と背凭れの間かつ座の後方下部で、背凭れの傾動に伴って相対距離の変化する２点間に介在するように接続されたバネを有したものが知られている。そしてこれらの椅子は、背凭れアームに固定した背凭れを後傾させた場合にも、バネが背凭れ又は座を起立姿勢に傾動させる傾動力を付与することで常に起立姿勢に戻るように構成されている。
【０００３】
【特許文献１】
特開平７−２５５５６２号公報
【０００４】
【発明が解決しようとする課題】
ところで、これらチルト機構を有した椅子は、通常、背凭れを後傾させていくに従って、着座者が背凭れにかけなければならない力が直線的に増加し、背凭れを大きく後傾させようと思えば大きな力が必要になる。
【０００５】
背凭れの後傾量が大きくなってくると、着座者はその上半身の体重を背凭れにかけることで背凭れを後傾させていくことになるが、体重をかけるだけでなく筋力を使わないと大きく後傾できなかったり、小柄な人や体重の軽い女性などは満足に後傾姿勢がとれなかったりする。
【０００６】
また小さな力で済むように、背凭れを最大限後傾させた場合でもバネの圧縮量を小さく設定したり、バネ定数の小さなバネを使用したりすると、背凭れが起立姿勢近傍に有るときのバネの初期傾動力も小さくなってしまい、着座者が背凭れに少しもたれただけで、意図しないほど大きく後傾してしまうという問題が有る。
【０００７】
また、通常、バネの傾動力を調整するための機構が有るが、これはバネの初期圧縮量を変えることで傾動させるための初期力を変更し、見かけ上のバネ定数を変化させるもので、背凭れの後傾に従って傾動力が直線的に増加することに変わりはない。
【０００８】
【課題を解決するための手段】
上記の問題点を簡易に解決するために、本発明に係る椅子は、脚の上部に取付けられていて上側に座部を有するベース部材と、このベース部材に対して相対的に回動可能に配置された背凭れアームと、背凭れアームに反力を付与する反力機構とを具備してなる椅子であって、前記反力機構が、背凭れアーム側に備えられた一方のバネ受け部と、一端側がベース部材に連結され背凭れアームをこえた他端側に他方のバネ受け部を有するバネ力伝達部材と、一方のバネ受け部と他方のバネ受け部の間に配置されたコイルスプリングとを有し、背凭れアームの後傾時にコイルスプリングを圧縮可能にするとともに、背凭れアームが後傾するに従って、背凭れアーム上でバネ力が作用している部分が回動しようとする接線方向に対して相対的に、コイルスプリングを圧縮する方向が徐々に変化していくように構成されているものである。そして、前記反力機構のバネ力伝達部材をベース部材に対し首振り不能に保持し、背凭れアームの後傾状態にかかわらず一方のバネ受け部の水平方向位置がバネ力伝達部材及び他方のバネ受け部に対し相対的にほぼ変わらないようにして、背凭れアーム上でバネ力が作用している部分が回動しようとする接線方向のみがベース部材に対して変化し、コイルスプリングを圧縮する方向がベース部材に対してほぼ変わらないように構成したことを特徴とする。
【０００９】
このようなものであれば、背凭れアームが後傾するに従い、コイルスプリングが圧縮されてコイルスプリングの全反力は大きくなっていくが、同時に背凭れアームが回動しようとする方向に対して、コイルスプリングの全反力の方向が徐々にずれていくため、コイルスプリングが背凭れアームを起立姿勢に戻そうとする反力の有効成分の大きさが増減することになる。背凭れアーム後傾時のコイルスプリングの圧縮の程度と方向のずれ方を設定することで、コイルスプリングが背凭れアームを起立姿勢に戻そうとする反力の変化具合をさまざまに設定でき、ひいては背凭れをチルトさせるための基本的なシステムを変更すること無く、椅子の座り心地の設計の自由度を大きくすることができる。しかも、一方のバネ受け部の水平方向位置をバネ力伝達部材や他方のバネ受け部に対して相対的にほぼ変わらないようにして、背凭れアーム上でバネ力が作用している部分が回動しようとする接線方向のみが変化し、コイルスプリングを圧縮する方向がほぼ一定方向を向いているようにしたので、例えばバネ受け部の水平方向位置がバネ力伝達部材及び他方のバネ受け部に対して相対的に移動し、これに伴ってコイルスプリングを圧縮する方向が変化する構成のものに比べて、背凭れの傾動角度と反力の増減の程度とを好適に比例させて反力を一定に保つような設計等が比較的容易になる上に、反力機構の各部の構成部材にスムーズな動作を付与することができ、またバネ受け部等に無理な力がかかることを有効に回避可能となるし、反力機構を被覆するカバーもコイルスプリングの動作に連動する可動のものにする必要がないため定位置に確実に取り付けておくことができるようになる。
【００１０】
これは、背凭れの後傾に連動して座がスライドや回転する背座シンクロチルト機構や、座が固定で背凭れのみ後傾する背チルト機構に適用することができる。
【００１１】
また、背凭れが起立姿勢近傍に有るときの背凭れ初期反力に対して、背凭れを大きく後傾させていったときの反力の増加程度をあまり大きくしないように設定するには、反力機構が、背凭れアーム上のバネを圧縮する作用点が回動しようとする接線方向とバネが圧縮される方向のなす角度を、背凭れアームが最も起立した姿勢から後傾するに従って大きくなっていくように変化させるものであることが好ましい。こうすることで、背凭れを後傾させていくに従ってコイルスプリングは圧縮されていくが、背凭れアームを起立姿勢に戻そうとする反力の有効成分の大きさとしては、コイルスプリングの圧縮度合いほど大きくならないようにすることができ、背凭れアームの回動接線方向とバネの方向のなす角度の変化のしかたの設定によっては、例えば、背凭れを後傾させる時、起立位置近傍ではほぼ直線的に背凭れ反力を増加させ、ある程度後傾させた位置からさらに後傾させる場合は背凭れ反力の増加程度を緩やかにしていくといったことも可能となる。
【００１２】
具体的な構造としては、反力機構の一方のバネ受け部がバネ力伝達部材にほぼ首振り不能に配置された別体の部材であり、当該一方のバネ受け部と背凭れアームとの間に、背凭れアームの後傾動作に伴い背凭れアーム上でバネ力が作用する部分をスライド移動させつつ一方のバネ受け部が受けるバネ力を当該背凭れアームに受圧させるスライド受圧機構を設けているものが挙げられる。
【００１３】
すなわち、背凭れアームが後傾すると、背凭れアーム上のバネ力が作用する部分が当該背凭れアーム上を次第に回転中心から遠い部位に移動することになるが、かかるスライド受圧機構を設ければ、このような部材同士が係り合った状態での相対動作を円滑に安定して行わせることができる。
【００１４】
好ましいスライド受圧機構としては、背凭れアーム側に設けた下向き凸状の受圧面と、一方のバネ受け部側に設けた上向き凹状の与圧面とから構成されるものが挙げられる。すなわち、背凭れアームが後傾すると、一方のバネ受け部のベース部材に対する角度がほぼ変わらないのに対して、背凭れアームのなす角度が漸次増大することになるが、上記のように構成しておけば、両部材の相対角度の如何に拘わらず、一方のバネ受け部から背凭れアームにバネ反力を、すべり等を生じることなく確実に伝達することができる。
【００１５】
勿論、本発明は、他のスライド受圧機構として、背凭れアーム側に設けたレール部と、このレール部に沿ってスライド移動可能となるように一方のバネ受け部側に設けたスライダとからなる構成を妨げるものではない。
【００１６】
背凭れアームが単一のものである場合には、この背凭れアームの一部に設けた孔にバネ力伝達部材を貫通させるとともに、その開口周辺にスライド受圧機構を構成しておけばよい。このようにすれば、当該スライド受圧機構を背凭れアームを利用してコンパクトかつ外観に極力影響を与えないように組み込むことが容易となる。
【００１７】
本発明は、コイルスプリングを圧縮する方向がベース部材に対してほぼ変わらないものであるため、他方のバネ受け部をバネ力伝達部材に対しほぼ首振り不能に配置した別体の部材として、反力機構の安定化と反力の調整の便とを有効に高めることができる。
【００１８】
よりコンパクトなシステムにするためには、反力機構を、バネ力伝達部材がコイルスプリングの内側を貫通するように配置されている構成にすることが考えられる。こうすることでスペースを有効に活用でき、コンパクトな設計が可能である。さらにこうすることで、背凭れを後傾させていったときに、コイルスプリングの方向が変化できる範囲は、バネ力伝達部材がコイルスプリングの内径に収まる範囲に限定される反面、コイルスプリングに外力など予想外の力が働いた場合にもバネ受けからコイルスプリングが外れるなどのトラブルを防ぐことができる。
【００１９】
さらに、背凭れアームの後傾動作に連動して動かない座部と、ベース部材下方に回転可能に軸止めされた背凭れアームとを備え、背凭れアームの回転軸より後部に前記反力機構を配置することで、椅子全体のシステムを背凭れのみのチルト機構として、シンプルかつ安価でありながら、後傾時の座り心地を大きく向上させることができる。
【００２０】
【発明の実施の形態】
以下、本発明の一実施の形態について図面を参照して説明する。
【００２１】
＜構造説明＞
本実施形態に係る椅子は、図１に側面図、図２に背面図を示すように、キャスタＣを有する脚羽根１１及び脚支柱１２からなる脚１と、この脚１に支持され座２を上部に有する支持体４と、この支持体４の後方から起立する背凭れ３とを具備するもので、背凭れ３を後傾させたときに座２は連動して動かない背のみのチルト機構を有する。
【００２２】
具体的な構造と部品構成について図３〜図７を参照して説明する。
【００２３】
すなわち、この椅子は、座２及び背凭れ３全体を昇降させるために前記脚支柱１２の内部に配置された図示しないガススプリングの上部に、ベース部材２１をその上部に有する支持体４を取付け、１本の背凭れアーム３１の前端部近傍を前記支持体４に背凭れアーム回転軸３２をもって回動可能に取り付けている。また、前記背凭れアーム３１は、その前部がベース部材２１の下方に位置するように配置され、座２の後端部より後方で上方に曲がって、その上部で背凭れ３を保持しており、背凭れアーム３１には、ベース部材２１の後端部近傍下方に該当する位置に受圧面３４１がくるように、バネ受けブラケット３４を一体に取り付けてある。
【００２４】
前記バネ受けブラケット３４は、椅子の前後方向に溝３４０を備えた下向きチャネル状をなすもので、左右の垂下壁の下面を下向き凸状に湾曲させて、当該下面を、バネ力を受ける受圧面３４１に設定している。これら背凭れアーム３１及びバネ受けブラケット３４には、バネ力伝達部材５３を前後方向に移動可能な状態で貫通させるための長穴３１０、３４６が設けてある。
【００２５】
次にコイルスプリングＳＰを上バネ受け部材５１のバネ受け面５１１と下バネ受け部材５２のバネ受け面５２１で挟まれるように配置し、ベース部材２１の後端部近傍に、下端部にはネジが形成してあるバネ力伝達部材５３を下向きに、ベース部材２１に対して首振り、回転共に不可能なように取付け、このバネ力伝達部材５３に下方からスライド支持部材５４、上バネ受け部材５１、コイルスプリングＳＰ、下バネ受け部材５２を貫通させて、当該バネ力伝達部材５３の下端部に操作部ＳＳをねじ込んで固定する。操作部ＳＳのねじ込み加減によってコイルスプリングＳＰの初期圧縮量を変化させ、背凭れ３の全般的な反力を調整できるようにしている。ここで、スライド支持部材５４、上バネ受け部材５１及び下バネ受け部材５２には、バネ力伝達部材５３を移動不能な状態で貫通させるための丸穴が形成してある。これら両バネ受け部材５１、５２は、バネ力伝達部材５３に対して相対的に首振り動作をすることを要求されないためである。
【００２６】
スライド支持部材５４は、前記バネ受けブラケット３４と共に背凭れアーム３１と上バネ受け部材５１との間に介在して、背凭れアーム３１の後傾動作に伴い背凭れアーム３１上でバネ力が作用する部分をスライド移動させつつ上バネ受け部材５１が受けるバネ力を当該背凭れアーム３１に受圧させる本発明のスライド受圧機構５０を構成するものである。スライド支持部材５４は、下端を上バネ受け部材５１の上面に添設させ、上端に設けた突出部５４０を前記バネ受けブラケット３４の溝３４０内に前後方向へ相対移動可能に嵌め込んだ駒状のもので、突出部５４０の両側に位置するスライド支持部材５４の上面には、上向き凹状に湾曲した与圧面５４１が形成してある。この与圧面５４１は、背凭れ３が後傾するに従って、バネ力伝達部材５３の軸心上に位置するバネ受けブラケット３４の受圧面３４１が背凭れアーム３１の回転中心である背凭れアーム回転軸３２から次第に後方へ移動し、かつ高さ方向に降下しても、常に受圧面３４１の一定領域と接面した状態を保つような形状が付与されている。
【００２７】
上バネ受け部材５１は、鋼板を、上面の周囲に下向きの壁面を有する略円形皿形状に絞り加工したもので、この形状によって後述するコイルスプリングＳＰを安定して保持することができる。この上面は、前記スライド支持部材５４を安定して添接させるために、中央を若干窪ませてある。
【００２８】
下バネ受け部材５２は、同じく鋼板を、底面の周囲に上向きの壁面を有する略円形皿形状に絞り加工したもので、この形状によって後述するコイルスプリングＳＰを安定して保持することができる。
【００２９】
コイルスプリングＳＰは、前記上バネ受け部材５１と下バネ受け部材５２に挟まれるように配置される。
【００３０】
操作部ＳＳは、外形略円盤形状で中央部の厚み方向に、バネ力伝達部材５３の先端ねじ部５３２にねじ込まれる雌ねじが形成されている。図３〜図６においてこの操作部ＳＳは図示省略してある。
【００３１】
バネ力伝達部材５３は、半球型上端部の下面に四角柱型の回転止め部５３１を有し、その下面中央部から下向きに円柱型の軸部５３３が伸びており、軸部５３３の下端部近傍に前記先端ねじ部５３２が形成されている。一方、ベース部材２１は、後端部近傍において四角柱状の回転止め部嵌合穴２１３およびその下方に位置する円形穴２１４を設けることで、バネ力伝達部材５３の回転止め部５３１を回転止め部嵌合穴２１３に嵌合し、後述する操作部ＳＳをねじ込む際に、このバネ力伝達部材５３が一体に回転しないように保持できるようになっており、円形穴２１４を有することで、バネ力伝達部材５３の首振りを防止できるようになっている。
【００３２】
このベース部材２１の四角柱状の回転止め部嵌合穴２１３およびその下方に位置する円形穴２１４に上方からバネ力伝達部材５３を貫通させ、回転しないように配置すると同時に、このバネ力伝達部材５３に下方から、スライド支持部材５４、上バネ受け部材５１、コイルスプリングＳＰ、下バネ受け部材５２を貫通させ、先端ねじ部５３２に操作部ＳＳをねじ込むことで、バネ力伝達部材５３が貫通している全ての部材を固定している。また、操作部ＳＳのねじ込み量を加減することで、コイルスプリングＳＰの初期圧縮量を変化させ、背凭れ３の全般的な反力を調整するようになっている。
【００３３】
なお、この反力機構５は、メカ部カバーＭＣ（図１、図２参照）によって目隠しされるようにしている。メカ部カバーＭＣは、操作部ＳＳによる操作が可能なように当該操作部ＳＳを露出させるための開口、あるいは、背凭れアーム３１の後傾動作を妨げないためのスリットを対応部位に適宜有し、それ以外は上バネ受け部材５１、コイルスプリングＳＰ、下バネ受け部材５２を隠蔽することができる形状をなすもので、支持体４に固定して取り付けられる。
【００３４】
なお、以上において、上バネ受け部材５１、下バネ受け部材５２、バネ力伝達部材５３、コイルスプリングＳＰが、主として本発明の反力機構５を構成している。
【００３５】
＜動作説明＞
上記の構成による動作について以下に具体的に説明する。
【００３６】
図３は、背凭れ３が最も起立した姿勢を示したものであり、図５はその際の反力機構５周辺の拡大図である。この時背凭れアーム３１側のバネ受けブラケット３４は背凭れアーム回転軸３２の基端部とともに略水平姿勢にあり、かつスライド支持部材５４、上バネ受け部材５１、コイルスプリングＳＰ及び下バネ受け部材５２のほぼ中央真上にあって、スライド支持部材５４の与圧面５４１はバネ受けブラケット３４の受圧面３４１の前後方向ほぼ中央部位に接触している。コイルスプリングＳＰは、少なくとも背凭れアーム３１を起立位置に保持できるバネ反力を発生する程度には圧縮された状態であり、この時、バネ力の方向、すなわちコイルスプリングＳＰの中央を通った上下の長さ方向は、与圧面５４１と受圧面３４１が接触している部分がコイルスプリングＳＰの反力によって回動しようとする接線方向、すなわち背凭れアーム回転軸３２の基端部における延伸方向と直交する垂直上向き方向に向いており、この２つの方向はほぼ一致する。
【００３７】
よって、背凭れ直立姿勢近傍では、コイルスプリングＳＰの反力のほぼ全てが背凭れ３を起立姿勢に戻そうとする力になっている。但し、この時のコイルスプリングＳＰの圧縮量は少ないので、反力は小さい。
【００３８】
ここから背凭れアーム３１を後傾させていくと、受圧面３４１のうち与圧面５４１が接触している部分は、次第に背凭れアーム３１上、回転軸心から遠ざかる方向へ移動し、与圧面５４１の接触部分の高さ位置が次第に低くなっていくが、上バネ受け部材５１及び下バネ受け部材５２はコイルスプリングＳＰと共に水平方向定位置にあるため、コイルスプリングＳＰの反力の方向が常に垂直上向きであるのに対して、前記接触部分が背凭れアーム回転軸３２を中心に回転しようとする方向すなわち背凭れアーム３１の基端部の延伸方向と直交する方向は、背凭れアーム３１の後傾に伴ってその後傾角度分だけコイルスプリングＳＰの反力の方向に対してずれていくことになる。
【００３９】
図４は、背凭れ３を大きく後傾させた姿勢を示したものであり、図６はその際の反力機構５周辺の拡大図である。この時スライド支持部材５４の与圧面５４１は、バネ受けブラケット３４の受圧面３４１の後方位置に接触した状態にある。この時、前記接触部分の中心位置が回動しようとする方向すなわち当該中心位置を通り背凭れアーム３１の基端部と直交する方向は、コイルスプリングＳＰの反力の方向である垂直上向きに対して大きくずれている。
【００４０】
よって、この時大きく圧縮されたコイルスプリングＳＰの全反力Ｆ１に対して、背凭れアーム３１を起立姿勢に戻す方向に作用する反力成分Ｆｙは小さくなる。なお、コイルスプリングＳＰの全反力Ｆ１、受圧面３４１に作用する力の成分Ｆｘ、Ｆｙの大きさと方向は、概念的に表わしたものである。
【００４１】
ここまでの説明で明らかなように、バネ軸伝達部材５３の取り付け角度を変えたり、背凭れアーム３１の基端部に角度をもたせる等すれば、背凭れアーム３１が後傾していく過程でコイルスプリングＳＰが背凭れアーム３１を起立姿勢に戻そうとする反力の変化をさまざまに設定することができる。
【００４２】
＜実施形態の作用効果＞
以上のように、本実施形態は、脚１の上部に取付けられていて上側に座部を有するベース部材２１と、このベース部材２１に対して相対的に回動可能に配置された背凭れアーム３１と、背凭れアーム３１に反力を付与する反力機構５とを具備してなる椅子であり、前記反力機構５が、背凭れアーム３１側に備えられた上バネ受け部材５１と、一端側がベース部材２１に連結され背凭れアーム３１をこえた他端側に下バネ受け部材５２を有するバネ力伝達部材５３と、上バネ受け部材５１と下バネ受け部材５２の間に配置されたコイルスプリングＳＰとを有し、背凭れアーム３１の後傾時にコイルスプリングＳＰを圧縮可能にするとともに、背凭れアーム３１が後傾するに従って、背凭れアーム３１上でバネ力が作用している部分が回動しようとする接線方向に対して相対的に、コイルスプリングＳＰを圧縮する方向が徐々に変化していくように構成されるものである。そして、前記反力機構５のバネ力伝達部材５３をベース部材に対し首振り不能に保持し、背凭れアーム３１の後傾状態にかかわらず一方のバネ受け部５１の水平方向位置がバネ力伝達部材５３及び下バネ受け部材５２に対し相対的にほぼ変わらないようにして、背凭れアーム３１上でバネ力が作用している部分が回動しようとする接線方向のみがベース部材２１に対して変化し、コイルスプリングＳＰを圧縮する方向がベース部材２１に対してほぼ変わらないように構成している。
【００４３】
このため、背凭れアーム３１が後傾するに従い、コイルスプリングＳＰが圧縮されてコイルスプリングＳＰの全反力は大きくなっていくが、同時に背凭れアーム３１が回動しようとする方向に対して、コイルスプリングＳＰの全反力の方向が徐々にずれていくため、コイルスプリングＳＰが背凭れアーム３１を起立姿勢に戻そうとする反力の有効成分の大きさが増減することになる。背凭れアーム３１の後傾時におけるコイルスプリングＳＰの圧縮の程度と方向のずれ方を設定することで、コイルスプリングＳＰが背凭れアーム３１を起立姿勢に戻そうとする反力の変化具合をさまざまに設定でき、ひいては背凭れ３をチルトさせるための基本的なシステムを変更すること無く、椅子の座り心地の設計の自由度を大きくすることができる。しかも、上バネ受け部材５１の水平方向位置をバネ力伝達部材５３や下バネ受け部材５２に対して相対的にほぼ変わらないようにして、背凭れアーム３１上でバネ力が作用している部分が回動しようとする接線方向のみが変化し、コイルスプリングＳＰを圧縮する方向がほぼ一定方向を向いているようにしたので、例えば上バネ受け部材５１の水平方向位置がバネ力伝達部材５３及び下バネ受け部材５２に対して相対的に移動し、これに伴ってコイルスプリングＳＰを圧縮する方向が変化する構成のものに比べて、背凭れ３の傾動角度と反力の増減の程度とを好適に比例させて反力を一定に保つ設計等を比較的容易に行えるようになる上に、反力機構５の各部の構成部材にスムーズな動作を付与することができ、またバネ受け部材５１、５２等に無理な力がかかることを有効に回避可能となるし、反力機構５を被覆するメカ部カバーＭＣもコイルスプリングＳＰの動作に連動する可動のものにする必要がないため定位置に確実に取り付けておくことができるようになる。
【００４４】
また、背凭れ３が起立姿勢近傍に有るときの背凭れ初期反力に対して、背凭れ３を大きく後傾させていったときの反力の増加程度をあまり大きくしないように設定するために、反力機構５が、背凭れアーム３１上のバネを圧縮する受圧面３４１の中心が回動しようとする接線方向とバネが圧縮される方向のなす角度を、背凭れアーム３１が最も起立した姿勢から後傾するに従って大きくなっていくように変化させるものであるため、背凭れ３を後傾させていくに従ってコイルスプリングＳＰが圧縮されても、背凭れアーム３１を起立姿勢に戻そうとする反力の有効成分の大きさとしては、コイルスプリングＳＰの圧縮度合いほど大きくならないようにすることができる。そして、背凭れアーム３１の回動接線方向とバネの方向のなす角度の変化のしかたの設定によって、例えば、背凭れ３を後傾させる時、起立位置近傍ではほぼ直線的に背凭れ反力を増加させ、ある程度後傾させた位置からさらに後傾させる場合は背凭れ反力の増加程度を緩やかにしていくといった設定も容易に可能なものとなる。
【００４５】
具体的な構造として、本実施形態は、反力機構５の上バネ受け部材５１をバネ力伝達部材５３にほぼ首振り不能に配置された別体の部材とし、当該上バネ受け部材５１と背凭れアーム３１との間に、背凭れアーム３１の後傾動作に伴い背凭れアーム３１上でバネ力が作用する部分をスライド移動させつつ上バネ受け部材５１が受けるバネ力を当該背凭れアーム３１に受圧させるスライド受圧機構５０を設けており、背凭れアーム３１が後傾すると、背凭れアーム３１上のバネ力が作用する部分が当該背凭れアーム３１上を次第に回転中心から遠い部位に移動することになるが、かかるスライド受圧機構により、このような部材同士が係り合った状態での相対動作を円滑に安定して行わせることができる。
【００４６】
図７はバネ受けブラケット３４及びスライド支持部材５４の拡大図である。特に、そのスライド受圧機構５０を、背凭れアーム３１側に設けた下向き凸状の受圧面３４１と、上バネ受け部材５１側に設けた上向き凹状の与圧面５４１とから構成しているため、背凭れアーム３１が後傾し、上バネ受け部材５１のベース部材２１に対する角度がほぼ変わらないのに対して、背凭れアーム３１のなす角度が漸次増大することになっても、両部材の相対角度の如何に拘わらず、上バネ受け部材５１から背凭れアーム３１にバネ反力をすべり等を生じることなく確実に伝達することができ、伝達ロスを防ぐとともに安定した確実な挙動を確保することができる。
【００４７】
また、この実施形態は、背凭れアーム３１が単一のものであるが、背凭れアーム３１の一部に設けた孔にバネ力伝達部材５３を貫通させるとともに、その開口周辺にスライド受圧機構５０を構成しているため、コンパクトで極力外部に露出しないように当該スライド受圧機構５０を組み込むことを可能にしているものである。勿論、背凭れアームが例えば２本平行に設けられるような場合にも、左右の背凭れアーム間にコイルスプリングＳＰの圧縮力を受ける部材を配置するなどすれば、この実施形態に準じた作用効果を得ることは可能である。
【００４８】
さらに、本実施形態は、コイルスプリングＳＰを圧縮する方向がベース部材２１に対してほぼ変わらないものであるため、下バネ受け部材５２をバネ力伝達部材５３に対しほぼ首振り不能に配置した別体の部材として、反力機構５の安定化と反力調整の便とを有効に高めることが可能となる。
【００４９】
また、バネ力伝達部材５３は、スライド支持部材５４、上バネ受け部材５１、コイルスプリングＳＰ、下バネ受け部材５２、操作部ＳＳを貫通して配置されており、これによって、スペースの有効活用がされてコンパクトなシステムとなり、また、予想外の力が働いた場合にも上・下バネ受け部材５１・５２からコイルスプリングＳＰが外れるなどのトラブルを防止することができる。
【００５０】
さらに、ベース部材２１および座２と、背凭れアーム３１の連動機構を設置しないものであり、ベース部材２１および座２は、背凭れアーム３１の後傾動作に連動して動かず、また、背凭れアーム回転軸３２より後方に前記反力機構５を配置することで、椅子全体のシステムを背凭れのみのチルト機構として、シンプルかつ安価でありながら、後傾時の座り心地を大きく向上させることができる。ただし、本発明はこれに限らず、背座の動作を連動させた背座シンクロチルト機構に適用させたり、座の前方に前記反力機構５を配置することもできる。この場合は、基本的にベース部材の前端部を回転可能に取り付け、背座をリンク機構を始めとして何らかの形で連動させるだけで容易に構成することが可能である。
【００５１】
なお、本発明は、以上に示した以外にも、種々変形が可能である。
【００５２】
例えば、凹凸の関係を変えたものとして、前記スライド支持部材５４と前記バネ受けブラケット３４の代わりに、図８のようなスライド支持部材５４２およびバネ受けブラケット３４２を設けることができる。
【００５３】
スライド支持部材５４２およびバネ受けブラケット３４２は、前記スライド支持部材５４および前記バネ受けブラケット３４と同様、背凭れアーム３１と上バネ受け部材５１との間に介在して、背凭れアーム３１の後傾動作に伴い背凭れアーム３１上でバネ力が作用する部分をスライド移動させつつ上バネ受け部材５１が受けるバネ力を当該背凭れアーム３１に受圧させるスライド受圧機構を構成するものである。バネ受けブラケット３４２は、椅子の前後方向に突出部を設けた断面略Ｔ字状をなすもので、該突出部を前後方向に下向き凸状に湾曲させて、当該下面をバネ力を受ける受圧面３４３に設定している。スライド支持部材５４２は、下端を上バネ受け部材５１の上面に添設させ、上端に設けた溝部を前記バネ受けブラケット３４２の突出部に前後方向へ相対移動可能に挿み込んだチャネル状のもので、該チャネルの溝部に位置するスライド支持部材５４２の上面には、凹状に湾曲した与圧面５４３が形成してある。この与圧面５４３は、背凭れ３が後傾するに従って、バネ力伝達部材５３の軸心上に位置するバネ受けブラケット３４２の受圧面３４３が背凭れアーム３１の回転中心から次第に後方へ移動し、かつ高さ方向に降下しても、常に受圧面３４３の一定領域と接面した状態を保つよう形状が付与されている。
【００５４】
また、他の構造からなるスライド受圧機構として、図９、１０に示すように、背凭れアーム３１側に設けたレール部３４４と、このレール部３４４に沿ってスライド移動可能となるように上バネ受け部材５１側に設けたスライダ５４４とからなる構成を採用することができる。図１１はレール部３４４およびスライダ５４４の拡大図である。このスライダ５４４の上面には、平面状の与圧面５４５が形成してある。このような構成は、背凭れ３の後傾に伴って与圧面５４５がレール部３４４に沿って後方にスライド移動することにより、バネ力伝達部材５３の軸心上に位置するレール部３４４の受圧面３４５が背凭れアーム３１の回転中心から次第に後方へ移動し、かつ高さ方向に降下しても、常に受圧面３４５の一定領域と接面した状態を保つよう形状が付与されている。この受圧機構の場合、スライダ５４４がレール部３４４に沿って後方にスライド移動する際、スライダ５４４のなす角度が上バネ受け部材５１に対して相対的に変化するが、上バネ受け部材５１の上部とスライダ５４４が、半円柱状のスライダ回転部５４６により回動可能に保持されているため、スライダ５４４はレール部３４４に沿って安定してスライド移動することができる。
【００５５】
【発明の効果】
以上に詳述した本発明の椅子は、背凭れアームが後傾し、コイルスプリングが圧縮されるに従い、背凭れアームが回動しようとする方向に対して、コイルスプリングの全反力の方向が徐々にずれていくような構成を、上下のバネ受け部を首振りさせることなく実現したので、背凭れをチルトさせるための基本的なシステムを変更すること無く、椅子の座り心地の設計の自由度を簡単な構成で有効に高めることが可能となる。
【図面の簡単な説明】
【図１】本発明の一実施形態を示す側面図。
【図２】同実施形態の背面図。
【図３】同実施形態の部分側面図。
【図４】図３に対応した作用説明図。
【図５】図３の要部拡大断面図。
【図６】図４の要部拡大断面図。
【図７】同実施形態の要部分解斜視図。
【図８】同実施形態の変形例を示す図。
【図９】本発明の他の実施形態を示す要部拡大側断面図。
【図１０】図９に対応した作用説明図。
【図１１】図９に対応した要部分解斜視図。
【符号の説明】
１…脚
１１…脚羽根
１２…脚支柱
２…座
２１…ベース部材
３…背凭れ
３１…背凭れアーム
３２…背凭れアーム回転軸
３４、３４２…バネ受けブラケット
３４１、３４３、３４５…受圧面
３４４…レール部
５…反力機構
５１…上バネ受け部材
５２…下バネ受け部材
５３…バネ力伝達部材
５３１…回転止め部
５３２…先端ねじ部
５４、５４２…スライド支持部材
５４１、５４３、５４５…与圧面
５４４…スライダ
５４６…スライダ回転部
ＳＰ…コイルスプリング[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a chair having a tilt mechanism that can tilt a backrest.
[0002]
[Prior art]
Conventionally, chairs having various backrest tilt mechanisms including a back seat synchro tilt and a back only tilt have been developed, but typically, as shown in Patent Document 1, a base for attaching legs and the like is disclosed. A member and a backrest arm having a base end rotatably supported by the base member.In the case of a back seat synchro tilt, the front end is slidably and rotatably supported by the base member. The seat has a rear end rotatably supported near the base end of the backrest arm, and a spring connected to a lower part of the seat so as to be interposed between two points whose relative distance changes with tilting. In the case of a tilt of the back only, the lower part of the seat near the base end of the backrest arm, or the lower part of the seat between the base end of the backrest arm and the backrest and the lower part of the seat, as the backrest tilts, Has a spring connected so as to be interposed between two points where the distance changes There has been known was. These chairs are configured such that even when the backrest fixed to the backrest arm is tilted backward, the spring always returns to the upright posture by applying a tilting force for tilting the backrest or the seat to the upright posture. Have been.
[0003]
[Patent Document 1]
JP-A-7-255562
[0004]
[Problems to be solved by the invention]
By the way, in chairs having these tilt mechanisms, usually, as the backrest is tilted backward, the force that the occupant has to apply to the backrest increases linearly, and it seems that the backrest tilts greatly back. Great power is needed.
[0005]
When the amount of back leaning increases, the seated person leans back by applying the weight of the upper body to the backrest, but not only applies weight but also does not use muscle strength It is difficult to lean backward, or a small person or a woman with a light weight cannot satisfactorily lean backward.
[0006]
Also, if the backrest is tilted backward as much as possible, setting the compression amount of the spring to a small value or using a spring with a small spring constant will prevent the backrest from being in the vicinity of the upright posture. There is also a problem that the initial tilting power of the spring becomes small, and the occupant leans back a little more than intended even if the seated person leans slightly on the backrest.
[0007]
In addition, there is usually a mechanism for adjusting the tilting power of the spring, but this is to change the initial force for tilting by changing the initial compression amount of the spring, and to change the apparent spring constant, The tilting power increases linearly as the backrest leans.
[0008]
[Means for Solving the Problems]
In order to easily solve the above problems, a chair according to the present invention includes a base member attached to an upper portion of a leg and having a seat portion on an upper side, and a rotatable relative to the base member. A chair comprising: a backrest arm disposed therein; and a reaction force mechanism for applying a reaction force to the backrest arm, wherein the reaction force mechanism is provided on one side of the backrest arm. A spring force transmitting member having one end side connected to the base member and the other end receiving the backrest arm and having the other spring receiving portion; and a coil disposed between the one spring receiving portion and the other spring receiving portion. A spring that allows the coil spring to be compressed when the backrest arm is tilted backward, and that a portion of the backrest arm where a spring force is acting tends to rotate as the backrest arm is tilted rearward. Relative to the tangent direction, Direction to compress the spring is one that is configured to change gradually. Then, the spring force transmitting member of the reaction force mechanism is held so as not to swing with respect to the base member, and the horizontal position of one spring receiving portion is set to the spring force transmitting member and the other, regardless of the backward tilt state of the backrest arm. Only the tangential direction where the spring force is acting on the backrest arm is changed relative to the base member so that the coil spring is compressed. It is characterized in that the direction in which the movement is performed is not substantially changed with respect to the base member.
[0009]
In such a case, as the backrest arm tilts backward, the coil spring is compressed and the total reaction force of the coil spring increases, but at the same time, the direction in which the backrest arm tends to rotate is Since the direction of the total reaction force of the coil spring gradually shifts, the magnitude of the effective component of the reaction force for the coil spring to return the backrest arm to the upright posture increases or decreases. By setting the degree of compression of the coil spring and the direction of displacement when the backrest arm is tilted backward, the degree of change in the reaction force of the coil spring to return the backrest arm to the upright posture can be set in various ways. The degree of freedom in designing the sitting comfort of the chair can be increased without changing the basic system for tilting the backrest. In addition, the horizontal position of one of the spring receiving portions is kept substantially unchanged with respect to the spring force transmitting member and the other spring receiving portion, so that the portion where the spring force is acting on the backrest arm is rotated. Since only the tangential direction to move is changed and the direction of compressing the coil spring is directed to a substantially constant direction, for example, the horizontal position of the spring receiving portion is moved to the spring force transmitting member and the other spring receiving portion. In contrast to the configuration in which the direction of compression of the coil spring changes with the movement of the coil spring, the tilt angle of the backrest and the degree of increase / decrease of the reaction force are appropriately proportional to the reaction force. In addition to making it relatively easy to design to keep it constant, it can provide smooth operation to the components of each part of the reaction force mechanism, and effectively prevent excessive force from being applied to the spring receiving part etc. Can be avoided and the reaction machine Cover covering also be able to be securely attached in place since it is not necessary to those of the movable interlocked with the operation of the coil spring to.
[0010]
This can be applied to a back-seat synchro-tilt mechanism in which the seat slides and rotates in conjunction with the backward tilt of the backrest, and a back-tilt mechanism in which the seat is fixed and only the backrest tilts backward.
[0011]
Also, in order to set the degree of increase in the reaction force when the backrest is greatly inclined backward with respect to the initial reaction force of the backrest when the backrest is in the vicinity of the standing posture, the reaction The force mechanism increases the angle between the tangential direction in which the action point for compressing the spring on the backrest arm is about to rotate and the direction in which the spring is compressed, as the backrest arm is tilted backward from the most upright position. It is preferable that the change is made in such a manner as to change. By doing so, the coil spring is compressed as the backrest is tilted backward, but the effective component of the reaction force for returning the backrest arm to the upright posture is determined by the compression degree of the coil spring. Depending on the setting of the change in the angle between the rotation tangent direction of the backrest arm and the direction of the spring, for example, when the backrest is tilted backward, an almost straight line near the standing position In the case where the backrest reaction force is increased and the backrest reaction force is further inclined backward from a position inclined backward to some extent, it is possible to gradually increase the degree of the backrest reaction force.
[0012]
As a specific structure, one of the spring receiving portions of the reaction force mechanism is a separate member that is arranged on the spring force transmitting member so as to be substantially non-swingable, and between the one spring receiving portion and the backrest arm. A sliding pressure receiving mechanism for receiving a spring force received by one of the spring receiving portions while applying pressure to the backrest arm while sliding the portion on which the spring force acts on the backrest arm in accordance with the backward tilting operation of the backrest arm. Are included.
[0013]
That is, when the backrest arm is tilted backward, the portion of the backrest arm on which the spring force acts gradually moves on the backrest arm to a portion farther from the center of rotation, but if such a slide pressure receiving mechanism is provided, The relative operation in a state where such members are engaged with each other can be performed smoothly and stably.
[0014]
As a preferred slide pressure receiving mechanism, there is a mechanism configured of a downwardly convex pressure receiving surface provided on the backrest arm side and an upwardly concave pressure receiving surface provided on one spring receiving portion side. That is, when the backrest arm is tilted backward, the angle formed by the backrest arm gradually increases while the angle of one of the spring receiving portions with respect to the base member hardly changes. By doing so, regardless of the relative angle between the two members, the spring reaction force can be reliably transmitted from one spring receiving portion to the backrest arm without causing any slippage or the like.
[0015]
Of course, the present invention includes, as another slide pressure receiving mechanism, a rail portion provided on the backrest arm side and a slider provided on one spring receiving portion side so as to be slidable along the rail portion. It does not hinder the configuration.
[0016]
When a single backrest arm is used, a spring force transmitting member may be passed through a hole provided in a part of the backrest arm, and a slide pressure receiving mechanism may be configured around the opening. This makes it easy to incorporate the slide pressure receiving mechanism using the backrest arm so as to be compact and minimize the appearance.
[0017]
According to the present invention, since the direction in which the coil spring is compressed is substantially the same as that of the base member, the other spring receiving portion is formed as a separate member that is arranged almost incapable of swinging with respect to the spring force transmitting member. It is possible to effectively enhance the stabilization of the force mechanism and the convenience of adjusting the reaction force.
[0018]
In order to make the system more compact, it is conceivable that the reaction force mechanism has a configuration in which the spring force transmission member is disposed so as to pass through the inside of the coil spring. In this way, space can be effectively used, and a compact design can be achieved. Further, when the backrest is tilted backward, the range in which the direction of the coil spring can be changed is limited to a range in which the spring force transmitting member is within the inner diameter of the coil spring, but the external force is applied to the coil spring. Even when an unexpected force is applied, troubles such as the coil spring coming off the spring receiver can be prevented.
[0019]
A backrest arm rotatably fixed below the base member, wherein the reaction force mechanism is provided rearward of the rotation axis of the backrest arm; With this arrangement, it is possible to greatly improve the sitting comfort when leaning backward, while using the entire chair system as a tilt mechanism using only the backrest, while being simple and inexpensive.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0021]
<Structure description>
As shown in a side view in FIG. 1 and a rear view in FIG. 2, the chair according to the present embodiment includes a leg 1 including a leg blade 11 having a caster C and a leg support 12, and a seat 2 supported by the leg 1. It has a support member 4 provided on the upper part and a backrest 3 standing upright from the rear of the support member 4, and the seat 2 does not move in conjunction with the backrest 3 when the backrest 3 is tilted backward. Having.
[0022]
The specific structure and component configuration will be described with reference to FIGS.
[0023]
That is, in this chair, a support 4 having a base member 21 on an upper portion thereof is attached to an upper portion of a gas spring (not shown) arranged inside the leg support 12 for raising and lowering the entire seat 2 and the backrest 3. The vicinity of the front end of one backrest arm 31 is rotatably attached to the support 4 with a backrest arm rotation shaft 32. The backrest arm 31 is disposed so that its front portion is located below the base member 21, bends upward behind the rear end of the seat 2, and holds the backrest 3 at its upper portion. A spring receiving bracket 34 is integrally attached to the backrest arm 31 so that the pressure receiving surface 341 is located at a position corresponding to a position below and near the rear end of the base member 21.
[0024]
The spring receiving bracket 34 has a downward channel shape provided with a groove 340 in the front-rear direction of the chair. The lower surfaces of the left and right hanging walls are curved downward and convex, and the lower surface is subjected to a pressure-receiving surface receiving a spring force. 341 is set. The backrest arm 31 and the spring receiving bracket 34 are provided with long holes 310 and 346 for allowing the spring force transmitting member 53 to pass therethrough so as to be movable in the front-rear direction.
[0025]
Next, the coil spring SP is disposed so as to be sandwiched between the spring receiving surface 511 of the upper spring receiving member 51 and the spring receiving surface 521 of the lower spring receiving member 52, and a screw is provided near the rear end of the base member 21 and at the lower end. Is attached to the base member 21 so that the spring force transmission member 53 is swung downward and cannot be rotated. The slide support member 54 and the upper spring receiving member are attached to the spring force transmission member 53 from below. 51, the coil spring SP, and the lower spring receiving member 52 are penetrated, and the operating portion SS is screwed and fixed to the lower end of the spring force transmitting member 53. The initial compression amount of the coil spring SP is changed by adjusting the screwing of the operation part SS so that the overall reaction force of the backrest 3 can be adjusted. Here, the slide support member 54, the upper spring receiving member 51, and the lower spring receiving member 52 are formed with round holes through which the spring force transmitting member 53 is immovably penetrated. This is because these spring receiving members 51 and 52 are not required to perform a swing operation relative to the spring force transmitting member 53.
[0026]
The slide supporting member 54 is interposed between the backrest arm 31 and the upper spring receiving member 51 together with the spring receiving bracket 34, and a spring force acts on the backrest arm 31 with the backward leaning operation of the backrest arm 31. The sliding pressure receiving mechanism 50 of the present invention in which the backrest arm 31 receives the spring force received by the upper spring receiving member 51 while sliding the moving portion. The slide support member 54 has a lower end attached to the upper surface of the upper spring receiving member 51, and a projection 540 provided at the upper end is fitted into the groove 340 of the spring receiving bracket 34 so as to be relatively movable in the front-rear direction. On the upper surface of the slide support member 54 located on both sides of the protruding portion 540, a pressurizing surface 541 curved in an upward concave shape is formed. As the backrest 3 tilts backward, the pressurizing surface 541 is configured such that the pressure receiving surface 341 of the spring receiving bracket 34 located on the axis of the spring force transmitting member 53 is a backrest arm rotation axis on which the backrest arm 31 is rotated. A shape is provided such that it gradually moves rearward from 32 and descends in the height direction and always keeps in contact with a certain area of the pressure receiving surface 341.
[0027]
The upper spring receiving member 51 is formed by drawing a steel plate into a substantially circular dish shape having a downward wall surface around its upper surface, and this shape can stably hold a coil spring SP described later. The upper surface is slightly depressed at the center in order to stably attach the slide support member 54.
[0028]
The lower spring receiving member 52 is similarly formed by drawing a steel plate into a substantially circular dish shape having an upward wall surface around the bottom surface, and this shape can stably hold a coil spring SP described later.
[0029]
The coil spring SP is disposed so as to be sandwiched between the upper spring receiving member 51 and the lower spring receiving member 52.
[0030]
The operation portion SS has a substantially disk-shaped outer shape, and is formed with a female screw that is screwed into the tip screw portion 532 of the spring force transmission member 53 in the thickness direction of the center portion. The operation section SS is not shown in FIGS.
[0031]
The spring force transmitting member 53 has a quadrangular prism-shaped rotation stopper 531 on the lower surface of the upper end of the hemispherical shape. A cylindrical shaft 533 extends downward from the center of the lower surface, and the lower end of the shaft 533. The tip screw portion 532 is formed in the vicinity. On the other hand, the base member 21 is provided with a quadrangular prism-shaped rotation stop fitting hole 213 and a circular hole 214 located therebelow in the vicinity of the rear end, thereby turning the rotation stop 531 of the spring force transmission member 53 into the rotation stop. The spring force transmission member 53 can be held so as not to rotate integrally when fitted into the fitting hole 213 and an operation portion SS to be described later is screwed. The swing of the transmission member 53 can be prevented.
[0032]
The spring force transmitting member 53 is penetrated from above into the square pillar-shaped rotation stopper fitting hole 213 of the base member 21 and the circular hole 214 located therebelow so as not to rotate. From below, the slide support member 54, the upper spring receiving member 51, the coil spring SP, and the lower spring receiving member 52 are penetrated, and the operating portion SS is screwed into the tip screw portion 532 so that the spring force transmitting member 53 penetrates. All members are fixed. Further, by adjusting the amount of screwing of the operation part SS, the initial compression amount of the coil spring SP is changed, and the overall reaction force of the backrest 3 is adjusted.
[0033]
Note that the reaction force mechanism 5 is blindfolded by a mechanical unit cover MC (see FIGS. 1 and 2). The mechanical unit cover MC has an opening for exposing the operation unit SS so that the operation by the operation unit SS can be performed, or a slit for appropriately preventing a back tilting operation of the backrest arm 31 at a corresponding portion. Otherwise, the upper spring receiving member 51, the coil spring SP, and the lower spring receiving member 52 have a shape that can be concealed, and are fixedly attached to the support body 4.
[0034]
In the above description, the upper spring receiving member 51, the lower spring receiving member 52, the spring force transmitting member 53, and the coil spring SP mainly constitute the reaction force mechanism 5 of the present invention.
[0035]
<Operation description>
The operation of the above configuration will be specifically described below.
[0036]
FIG. 3 shows a posture in which the backrest 3 stands most up, and FIG. 5 is an enlarged view around the reaction force mechanism 5 at that time. At this time, the spring receiving bracket 34 on the backrest arm 31 side is in a substantially horizontal posture together with the base end of the backrest arm rotating shaft 32, and the slide support member 54, the upper spring receiving member 51, the coil spring SP, and the lower spring receiving member. The pressurizing surface 541 of the slide support member 54 is located substantially at the center of the center 52 and is in contact with a substantially central portion in the front-rear direction of the pressure receiving surface 341 of the spring receiving bracket 34. The coil spring SP is in a compressed state at least to generate a spring reaction force capable of holding the backrest arm 31 in the upright position. At this time, the direction of the spring force, that is, the vertical direction passing through the center of the coil spring SP Is the tangential direction in which the portion where the pressurizing surface 541 and the pressure receiving surface 341 are in contact with each other tends to rotate by the reaction force of the coil spring SP, that is, the extending direction at the base end of the backrest arm rotating shaft 32. They are oriented in the perpendicular vertical upward direction, and these two directions almost coincide with each other.
[0037]
Therefore, in the vicinity of the backrest upright posture, almost all of the reaction force of the coil spring SP is a force for returning the backrest 3 to the upright posture. However, since the compression amount of the coil spring SP at this time is small, the reaction force is small.
[0038]
When the backrest arm 31 is tilted backward from here, the portion of the pressure receiving surface 341 which is in contact with the pressurized surface 541 gradually moves on the backrest arm 31 in a direction away from the rotation axis, and the pressurized surface 541 is moved. However, since the upper spring receiving member 51 and the lower spring receiving member 52 are in the horizontal fixed position together with the coil spring SP, the direction of the reaction force of the coil spring SP is always vertical. In contrast to the upward direction, the direction in which the contact portion attempts to rotate about the backrest arm rotation axis 32, that is, the direction orthogonal to the extension direction of the base end of the backrest arm 31, is opposite to the backrest arm 31. With the inclination, the coil spring SP shifts with respect to the direction of the reaction force by the inclination angle thereafter.
[0039]
FIG. 4 shows a posture in which the backrest 3 is greatly inclined backward, and FIG. 6 is an enlarged view of the vicinity of the reaction force mechanism 5 at that time. At this time, the pressurizing surface 541 of the slide support member 54 is in a state of being in contact with a position behind the pressure receiving surface 341 of the spring receiving bracket 34. At this time, the direction in which the center position of the contact portion is about to rotate, that is, the direction passing through the center position and orthogonal to the base end of the backrest arm 31 is perpendicular to the direction of the reaction force of the coil spring SP. Greatly shifted.
[0040]
Therefore, the reaction force component Fy acting in the direction of returning the backrest arm 31 to the upright posture becomes smaller with respect to the total reaction force F1 of the coil spring SP which is largely compressed at this time. The magnitude and direction of the total reaction force F1 of the coil spring SP and the force components Fx and Fy acting on the pressure receiving surface 341 are conceptually represented.
[0041]
As is clear from the above description, if the mounting angle of the spring shaft transmitting member 53 is changed, or if the base end of the backrest arm 31 is angled, the backrest arm 31 is inclined backward. The change in the reaction force by which the coil spring SP attempts to return the backrest arm 31 to the upright posture can be set variously.
[0042]
<Effects of Embodiment>
As described above, according to the present embodiment, the base member 21 attached to the upper portion of the leg 1 and having the seat portion on the upper side, and the backrest arm rotatably disposed relative to the base member 21 31 and a reaction force mechanism 5 that applies a reaction force to the backrest arm 31, wherein the reaction force mechanism 5 includes an upper spring receiving member 51 provided on the backrest arm 31 side; One end side is connected to the base member 21 and is disposed between the upper spring receiving member 51 and the lower spring receiving member 52, the spring force transmitting member 53 having a lower spring receiving member 52 at the other end beyond the backrest arm 31. A portion having a coil spring SP and allowing the coil spring SP to be compressed when the backrest arm 31 is tilted backward, and a spring force acting on the backrest arm 31 as the backrest arm 31 is tilted rearward. Will rotate Relative to the tangential direction, in which direction to compress the coil spring SP is configured to change gradually. The spring force transmitting member 53 of the reaction force mechanism 5 is held so as not to swing with respect to the base member, so that the horizontal position of the one spring receiving portion 51 is transmitted regardless of the backward tilt state of the backrest arm 31. Only the tangential direction in which the portion on which the spring force is acting on the backrest arm 31 is about to rotate is relatively fixed with respect to the base member 21 with respect to the member 53 and the lower spring receiving member 52. Thus, the direction in which the coil spring SP changes and the coil spring SP is compressed does not substantially change with respect to the base member 21.
[0043]
For this reason, as the backrest arm 31 is tilted backward, the coil spring SP is compressed and the total reaction force of the coil spring SP increases, but at the same time, Since the direction of the total reaction force of the coil spring SP gradually shifts, the magnitude of the effective component of the reaction force by which the coil spring SP attempts to return the backrest arm 31 to the upright posture increases or decreases. By setting the degree of compression and the direction of displacement of the coil spring SP when the backrest arm 31 is tilted backward, the degree of change in the reaction force of the coil spring SP to return the backrest arm 31 to the upright posture can be varied. Therefore, the degree of freedom in designing the sitting comfort of the chair can be increased without changing the basic system for tilting the backrest 3. In addition, the horizontal position of the upper spring receiving member 51 is kept substantially unchanged relative to the spring force transmitting member 53 and the lower spring receiving member 52, and the portion where the spring force acts on the backrest arm 31 Only the tangential direction in which the coil spring SP is to be changed changes so that the direction in which the coil spring SP is compressed is oriented in a substantially constant direction. For example, the horizontal position of the upper spring receiving member 51 is Compared to the configuration in which the direction of compressing the coil spring SP changes relative to the lower spring receiving member 52 and the direction in which the coil spring SP compresses accordingly, the tilt angle of the backrest 3 and the degree of increase or decrease of the reaction force are reduced. It is relatively easy to design such that the reaction force is kept constant in a suitable proportion, and it is possible to impart a smooth operation to the constituent members of each part of the reaction force mechanism 5 and to use the spring receiving member 51. , 52 Can be effectively avoided, and the mechanical cover MC for covering the reaction force mechanism 5 does not need to be movable in conjunction with the operation of the coil spring SP. It can be attached.
[0044]
Also, in order to set the degree of increase of the reaction force when the backrest 3 is largely inclined backward to the initial reaction force when the backrest 3 is in the vicinity of the standing posture so as not to be so large. The reaction force mechanism 5 sets the angle between the tangential direction in which the center of the pressure receiving surface 341 for compressing the spring on the backrest arm 31 is about to rotate and the direction in which the spring is compressed, so that the backrest arm 31 stands up most. Since it is changed so as to increase as it leans backward from the posture, even if the coil spring SP is compressed as the backrest 3 is leaned backward, the backrest arm 31 attempts to return to the standing posture. The magnitude of the effective component of the reaction force can be prevented from increasing as much as the degree of compression of the coil spring SP. By setting the manner in which the angle between the rotation tangent direction of the backrest arm 31 and the direction of the spring changes, for example, when the backrest 3 is tilted backward, the backrest reaction force is almost linearly near the standing position. In the case where the backrest is further increased from a position where the backrest is tilted to a certain degree, it is possible to easily set the backrest reaction force to be gradually increased.
[0045]
As a specific structure, in the present embodiment, the upper spring receiving member 51 of the reaction force mechanism 5 is a separate member that is disposed on the spring force transmitting member 53 so as to be substantially non-swingable. The spring force received by the upper spring receiving member 51 is moved between the backrest arm 31 and the portion where the spring force acts on the backrest arm 31 in accordance with the backward tilting operation of the backrest arm 31. When the backrest arm 31 is tilted backward, the portion of the backrest arm 31 where the spring force acts gradually moves on the backrest arm 31 to a position farther from the center of rotation. In other words, such a slide pressure receiving mechanism can smoothly and stably perform a relative operation in a state where such members are engaged with each other.
[0046]
FIG. 7 is an enlarged view of the spring receiving bracket 34 and the slide support member 54. In particular, since the slide pressure receiving mechanism 50 includes a downwardly convex pressure receiving surface 341 provided on the backrest arm 31 side and an upwardly concave concave pressurizing surface 541 provided on the upper spring receiving member 51 side. Although the angle of the back arm 31 is inclined backward and the angle of the upper spring receiving member 51 with respect to the base member 21 is almost unchanged, even if the angle formed by the back arm 31 is gradually increased, the relative angle between the two members is increased. Irrespective of the above, the spring reaction force can be reliably transmitted from the upper spring receiving member 51 to the backrest arm 31 without causing a slip or the like, and it is possible to prevent a transmission loss and secure a stable and reliable behavior. it can.
[0047]
In this embodiment, the backrest arm 31 is a single unit. However, the spring force transmitting member 53 is made to pass through a hole provided in a part of the backrest arm 31, and a slide pressure receiving mechanism 50 is provided around the opening. Therefore, it is possible to incorporate the slide pressure receiving mechanism 50 so as to be compact and not to be exposed to the outside as much as possible. Of course, even in the case where two backrest arms are provided in parallel, for example, if a member receiving the compressive force of the coil spring SP is arranged between the left and right backrest arms, the operation and effect according to this embodiment are achieved. It is possible to get
[0048]
Further, in the present embodiment, since the direction in which the coil spring SP is compressed is substantially the same as that of the base member 21, the lower spring receiving member 52 is arranged so as not to swing about the spring force transmitting member 53. As a body member, it is possible to effectively enhance the stability of the reaction force mechanism 5 and the convenience of adjusting the reaction force.
[0049]
Further, the spring force transmitting member 53 is disposed so as to penetrate the slide supporting member 54, the upper spring receiving member 51, the coil spring SP, the lower spring receiving member 52, and the operation portion SS, so that the space can be effectively used. As a result, a compact system can be obtained, and troubles such as the coil spring SP coming off from the upper and lower spring receiving members 51 and 52 can be prevented even when an unexpected force is applied.
[0050]
Furthermore, the base member 21 and the seat 2 are not provided with an interlocking mechanism of the backrest arm 31. The base member 21 and the seat 2 do not move in conjunction with the backward leaning operation of the backrest arm 31. By arranging the reaction force mechanism 5 behind the backrest arm rotation shaft 32, the overall chair system can be a simple and inexpensive tilt mechanism using only the backrest, while greatly improving the sitting comfort when leaning backward. Can be. However, the present invention is not limited to this, and may be applied to a backseat synchro tilt mechanism in which the movements of the backseat are linked, or the reaction force mechanism 5 may be arranged in front of the seat. In this case, basically, the front end of the base member can be rotatably mounted, and the back seat can be easily configured simply by interlocking with the link mechanism in some form.
[0051]
The present invention can be variously modified in addition to the above.
[0052]
For example, assuming that the relationship between the irregularities is changed, a slide support member 542 and a spring receiving bracket 342 as shown in FIG. 8 can be provided instead of the slide support member 54 and the spring receiving bracket 34.
[0053]
The slide supporting member 542 and the spring receiving bracket 342 are interposed between the backrest arm 31 and the upper spring receiving member 51, like the slide supporting member 54 and the spring receiving bracket 34, and tilt the backrest arm 31 backward. A sliding pressure receiving mechanism is configured so that the spring force received by the upper spring receiving member 51 is received by the back arm 31 while the portion on which the spring force acts on the back arm 31 is slid along with the operation. The spring receiving bracket 342 has a substantially T-shaped cross section provided with a protruding portion in the front-rear direction of the chair. 343. The slide support member 542 has a lower end attached to the upper surface of the upper spring receiving member 51, and a groove provided at the upper end is inserted into the protrusion of the spring receiving bracket 342 so as to be relatively movable in the front-rear direction. On the upper surface of the slide support member 542 located in the groove of the channel, a pressurized surface 543 curved in a concave shape is formed. As the backrest 3 tilts rearward, the pressure receiving surface 343 of the spring receiving bracket 342 located on the axis of the spring force transmitting member 53 gradually moves rearward from the rotation center of the backrest arm 31. Further, the shape is provided so as to always keep a state of being in contact with a certain region of the pressure receiving surface 343 even when it is lowered in the height direction.
[0054]
Further, as a slide pressure receiving mechanism having another structure, as shown in FIGS. 9 and 10, a rail portion 344 provided on the backrest arm 31 side, and an upper spring so as to be slidable along the rail portion 344. A configuration including the slider 544 provided on the receiving member 51 side can be adopted. FIG. 11 is an enlarged view of the rail section 344 and the slider 544. A flat pressurized surface 545 is formed on the upper surface of the slider 544. With such a configuration, the pressurizing surface 545 slides rearward along the rail portion 344 as the backrest 3 tilts backward, so that the pressure of the rail portion 344 located on the axis of the spring force transmitting member 53 is reduced. Even if the surface 345 gradually moves rearward from the rotation center of the backrest arm 31 and descends in the height direction, the shape is provided so that the surface 345 always keeps in contact with a certain area of the pressure receiving surface 345. In the case of this pressure receiving mechanism, when the slider 544 slides rearward along the rail portion 344, the angle formed by the slider 544 changes relatively to the upper spring receiving member 51. The slider 544 is rotatably held by the semi-cylindrical slider rotating portion 546, so that the slider 544 can stably slide along the rail portion 344.
[0055]
【The invention's effect】
In the chair of the present invention described in detail above, as the backrest arm tilts backward and the coil spring is compressed, the direction of the total reaction force of the coil spring with respect to the direction in which the backrest arm is about to rotate. Free to design the chair comfort without changing the basic system for tilting the backrest because the configuration that gradually shifts is realized without swinging the upper and lower spring receiving parts. The degree can be effectively increased with a simple configuration.
[Brief description of the drawings]
FIG. 1 is a side view showing an embodiment of the present invention.
FIG. 2 is a rear view of the embodiment.
FIG. 3 is a partial side view of the embodiment.
FIG. 4 is an operation explanatory view corresponding to FIG. 3;
FIG. 5 is an enlarged sectional view of a main part of FIG. 3;
FIG. 6 is an enlarged sectional view of a main part of FIG. 4;
FIG. 7 is an exploded perspective view of a main part of the embodiment.
FIG. 8 is a view showing a modification of the embodiment.
FIG. 9 is an enlarged side sectional view of a main part showing another embodiment of the present invention.
FIG. 10 is an operation explanatory view corresponding to FIG. 9;
FIG. 11 is an exploded perspective view of a main part corresponding to FIG. 9;
[Explanation of symbols]
1 ... Legs
11 ... Leg feather
12 ... leg support
2 ... seat
21 ... Base member
3. Backrest
31 ... Backrest arm
32: Backrest arm rotation axis
34, 342 ... spring receiving bracket
341, 343, 345 ... pressure receiving surface
344 ... Rail section
5: Reaction force mechanism
51 ... Upper spring receiving member
52 ... Lower spring receiving member
53 ... Spring force transmission member
531: Rotation stop
532: Tip thread
54, 542 ... Slide support member
541, 543, 545 ... Pressurized surface
544 ... Slider
546 ... Slider rotating unit
SP ... Coil spring

Claims

A base member attached to the upper part of the leg and having a seat on the upper side, a backrest arm rotatably arranged relative to the base member, and a reaction force for applying a reaction force to the backrest arm A chair comprising a mechanism,
The reaction force mechanism has one spring receiving portion provided on the backrest arm side, and a spring force transmitting member having the other spring receiving portion on one end side connected to the base member and over the backrest arm. Having a coil spring disposed between one spring receiving portion and the other spring receiving portion, and allowing the coil spring to be compressible when the backrest arm is tilted backward, and as the backrest arm is tilted rearward, The direction in which the coil spring is compressed gradually changes relative to the tangential direction in which the portion where the spring force is acting on the backrest arm is about to rotate,
The spring force transmitting member of the reaction force mechanism is held so as not to swing with respect to the base member, and the horizontal position of one of the spring receiving portions is determined by the spring force transmitting member and the other spring receiving member regardless of the reclined state of the backrest arm. The direction in which only the tangential direction in which the portion on which the spring force is acting on the backrest arm is about to rotate is changed relative to the base member so that the coil spring is compressed. The chair is configured so that it does not substantially change with respect to the base member.

The reaction force mechanism increases the angle between the tangential direction in which the action point compressing the spring on the backrest arm is about to rotate and the direction in which the spring is compressed, as the backrest arm tilts backward from the most upright position. 2. The chair according to claim 1, wherein the chair is changed so as to change.

One of the spring receiving portions of the reaction force mechanism is a separate member which is disposed on the spring force transmitting member so as to be substantially non-swingable, and is provided between the one spring receiving portion and the backrest arm after the backrest arm. A slide pressure receiving mechanism is provided, which slides a portion on the backrest arm where a spring force acts on the backrest arm while receiving the spring force received by one of the spring receiving portions while the backrest arm presses the spring force. Item 3. The chair according to item 1 or 2.

The chair according to claim 3, wherein the slide pressure receiving mechanism comprises a downwardly convex pressure receiving surface provided on the backrest arm side and an upwardly concave pressure receiving surface provided on one spring receiving portion side. .

The slide pressure receiving mechanism comprises a rail portion provided on the backrest arm side and a slider provided on one spring receiving portion side so as to be slidable along the rail portion. Item 3. The chair according to item 3.

The backrest arm is a single one, and a spring force transmitting member is penetrated through a hole provided in a part of the backrest arm, and a slide pressure receiving mechanism is configured around the opening. The chair according to claim 3, wherein

7. The chair according to claim 3, wherein the other spring receiving portion is a separate member that is disposed so as to be substantially non-swingable with respect to the spring force transmitting member.

The chair according to claim 7, wherein the spring force transmitting member of the reaction force mechanism is disposed so as to penetrate the inside of the coil spring.

A seat that does not move in conjunction with the backward tilting movement of the backrest arm, and a backrest arm rotatably fixed below the base member, and the reaction force mechanism is disposed behind the rotation axis of the backrest arm. The chair according to any one of claims 1 to 8, wherein the chair is provided.