JP2004183731A

JP2004183731A - Suspension coil spring

Info

Publication number: JP2004183731A
Application number: JP2002349675A
Authority: JP
Inventors: Shinsuke Okura; 伸介大倉; Kouji Gotou; 交司後藤
Original assignee: Chuo Hatsujo KK; Chuo Spring Co Ltd
Current assignee: Chuo Hatsujo KK; Chuo Spring Co Ltd
Priority date: 2002-12-02
Filing date: 2002-12-02
Publication date: 2004-07-02
Anticipated expiration: 2022-12-02
Also published as: JP4391080B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suspension coil spring adjustable to have desired lateral force by using a drum-shaped coil spring. <P>SOLUTION: In accordance with an axial compression load, the drum-shaped coil spring 10 gets into a state of a first spring constant range in a constant value, with a free winding number as total of each free winding number of a drum part 15, an upper gradually changing part 13, and a lower gradually changing part 14, a spring constant changing range where the free winding number is changed, or a second spring constant range in a constant value, with the free winding number that is roughly similar to the free winding number of the drum part. A first intermediate direction to bisectionally divide a free winding decimal part existing between radial directions of upper and lower free winding ends as seen from axially above when the drum-shaped coil spring is in the first spring constant range, and a second intermediate direction to bisectionally divide a free end decimal part existing between radial directions of upper and lower free winding ends as seen from axially above when it is in the second spring constant range are adjusted to have prescribed relation (the same direction, for example). In addition, the total free winding number is set to have a prescribed decimal value (about 0.5, for example). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、車両の懸架装置に用いる懸架コイルばねに関し、特に、軸方向圧縮荷重に対し非線形ばね特性を有する懸架コイルばねに係る。
【０００２】
【従来の技術】
車両の懸架装置に関しては、種々の形式のものが知られており、種々の要請に応じた特性に調整することが企図されている。例えば、有効巻部の巻数を負荷に応じて変化させるため、ピッチ、コイル径、線径等を調整し、軸方向圧縮荷重に対し非線形ばね特性を有する種々の懸架コイルばねが提案されている。このような非線形コイルばねとしては、例えば、胴部に最大径を有する樽形状を呈し、コイル素線の線径が軸方向中心から両端に向かって漸減するように両端部の素線を切削した特殊コイルばねが提案されている。
【０００３】
また、ニーアクションを行うサスペンションに要求されるばね特性も非線形であり、後輪用としてトレーリングアーム式サスペンションが知られている。これは、車両前方に配置したピボットと後輪の車軸をアームで結合し、ピボットを中心として上下方向に揺動し、所謂ニーアクションを行うもので、例えば下記の特許文献１及び２等に開示されている。このサスペンション構造は、車輪を懸架するサスペンションリンクと、車輪のバンプ・リバウンドの動きを緩衝する緩衝装置によって構成されているが、特許文献１及び２の何れにも懸架コイルばねの構成については言及されていない。
【０００４】
【特許文献１】
特開２００２−４６４４３号公報
【特許文献２】
特開平８−２６８０１８号公報
【０００５】
【発明が解決しようとする課題】
前掲の特殊コイルばねにおいては、両端部の線径が漸減するように形成することは容易ではなく、量産に適さず、必然的に高価となる。而して、少なくとも線径を変化させることなく所望の非線形特性を確保することが望まれている。このような要請に応え得る懸架コイルばねとしては、鼓形状の圧縮コイルばね、即ち鼓型コイルばねが有効である。この鼓型コイルばねは、上側座巻部及び下側座巻部と、これら上側座巻部及び下側座巻部から夫々軸方向中心に向かって外径が漸減する上側徐変部及び下側徐変部と、これら上側徐変部及び下側徐変部の最小径部に連続する略同径の胴部を備え、外形が鼓形状を呈するものであり、所望の非線形特性を容易に設定することができる。特に、車両の懸架装置においては、所望の（大きさ及び／又は方向の）横力に調整し得る懸架コイルばねが望まれており、これには鼓型コイルばねが好適である。
【０００６】
そこで、本発明は、軸方向圧縮荷重に対し非線形ばね特性を有する懸架コイルばねにおいて、鼓型コイルばねを用い、所望の横力に調整し得る懸架コイルばねを提供することを課題とする。
【０００７】
【課題を解決するための手段】
上記の課題を解決するため、本発明は請求項１に記載のように、上側座巻部及び下側座巻部と、該上側座巻部及び下側座巻部から夫々軸方向中心に向かって外径が漸減する上側徐変部及び下側徐変部と、該上側徐変部及び下側徐変部の最小径部に連続する略同径の胴部を備えた鼓型コイルばねから成り、該鼓型コイルばねに対する軸方向圧縮荷重に応じて、当該鼓型コイルばねの自由巻数が前記胴部並びに前記上側徐変部及び下側徐変部の各自由巻数の総和であって一定の値である第１のばね定数域、当該鼓型コイルばねの自由巻数が変化するばね定数変化域、及び当該鼓型コイルばねの自由巻数が前記胴部の自由巻数と略等しい一定の値である第２のばね定数域の何れかの状態となる懸架コイルばねにおいて、前記鼓型コイルばねが前記第１のばね定数域にあるときに前記鼓型コイルばねの軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第１の中間方向と、前記鼓型コイルばねが前記第２のばね定数域にあるときに前記鼓型コイルばねの軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第２の中間方向とを所定の関係に調整すると共に、前記鼓型コイルばねの総自由巻数の小数値を所定の値に設定することとしたものである。
【０００８】
上記の上側徐変部及び下側徐変部は、鼓型コイルばねが第１のばね定数域にあるときには夫々上側座巻部及び下側座巻部との境界を画し、鼓型コイルばねが第２のばね定数域となったときには線間接触又は座と接触して夫々上側座巻部及び下側座巻部と一体化し、夫々胴部との境界を画す部分であり、この部分を線間接触又は座との接触に応じて自由巻端が移動することになる。そして、第１のばね定数域と第２のばね定数域との間が、ばね定数変化域となる。これにより、横力の方向及び大きさを所望の方向及び値に調整することができる。
【０００９】
前記請求項１に記載の懸架コイルばねにおいて、更に、請求項２に記載のように、前記第１の中間方向と前記第２の中間方向を一致させると共に、前記鼓型コイルばねが前記第１のばね定数域及び前記第２のばね定数域にあるときの前記鼓型コイルばねの総自由巻数の小数値を夫々略０．５に設定することとすれば、横力を最大値に調整することができる。特に、この記請求項２に記載の懸架コイルばねにおいて、請求項３に記載のように、前記第１及び第２の中間方向を、前記下側座巻部の端末からの巻数で設定した目標横力方向に対し、前記鼓型コイルばねの軸方向上方からみて前記鼓型コイルばねの上側に向かって＋０．２５巻の方向に設定することとすれば、横力を最大値に調整すると共に、目標とする方向に調整することができる。
【００１０】
あるいは、前記請求項１に記載の懸架コイルばねにおいて、請求項４に記載のように、前記鼓型コイルばねが前記第１のばね定数域及び前記第２のばね定数域にあるときの前記鼓型コイルばねの総自由巻数の小数値を夫々略０．０に設定することとすれば、横力を最小値に調整することができる。
【００１１】
更に、前記請求項１に記載の懸架コイルばねにおいて、請求項５に記載のように、前記鼓型コイルばねが前記第１のばね定数域にあるときの総自由巻数の小数値を略０．０に設定すると共に、前記鼓型コイルばねが前記第２のばね定数域にあるときの総自由巻数の小数値を略０．５に設定し、且つ前記第２の中間方向を、前記下側座巻部の端末からの巻数で設定した目標横力方向に対し、前記鼓型コイルばねの軸方向上方からみて前記鼓型コイルばねの上側に向かって＋０．２５巻の方向に設定することとすれば、前記鼓型コイルばねのたわみ量の増加途中から目標とする方向に横力を増加させることができる。
【００１２】
あるいは、前記請求項１に記載の懸架コイルばねにおいて、請求項６に記載のように、前記第１の中間方向を、前記下側座巻部の端末からの巻数で設定した目標横力方向に対し、前記鼓型コイルばねの軸方向上方からみて前記鼓型コイルばねの上側に向かって＋０．２５巻の方向に設定すると共に、前記第１の中間方向と前記第２の中間方向とを逆方向に設定し、且つ前記鼓型コイルばねが前記第１のばね定数域にあるときの総自由巻数の小数値を略０．５に設定すると共に、前記鼓型コイルばねが前記第２のばね定数域にあるときの総自由巻数の小数値を略０．０に設定することとすれば、前記鼓型コイルばねのたわみ量の増加途中から目標とする方向に横力を減少させることができる。
【００１３】
【発明の実施の形態】
以下、本発明の実施形態を、図面を参照して説明する。図１は本発明の懸架コイルばねに供する鼓型コイルばねの一実施形態に係り、懸架装置への装着前の状態を示すものである。本実施形態の鼓型コイルばね１０は、図１の右側に概略範囲で示したように、上側座巻部１１及び下側座巻部１２と、これら上側座巻部１１及び下側座巻部１２から夫々軸方向中心に向かって外径が漸減する上側徐変部１３及び下側徐変部１４と、これら上側徐変部１３及び下側徐変部１４の最小径部に連続する略同径の胴部１５を備えた鼓形状に形成されており、軸方向圧縮荷重に対し非線形ばね特性を有する。
【００１４】
即ち、軸方向圧縮荷重に応じて、鼓型コイルばね１０の自由巻数が胴部１５並びに上側徐変部１３及び下側徐変部１４の各自由巻数の総和であって一定の値である第１のばね定数域、鼓型コイルばね１０の自由巻数が変化するばね定数変化域、及び鼓型コイルばね１０の自由巻数が胴部１５の自由巻数と略等しい一定の値である第２のばね定数域の何れかの状態となる。従って、上側徐変部１３及び下側徐変部１４は、鼓型コイルばね１０が第１のばね定数域にあるときには夫々上側座巻部１１及び下側座巻部１２との境界を画し、鼓型コイルばね１０が第２のばね定数域となったときには線間接触又は座と接触して夫々上側座巻部１１及び下側座巻部１２と一体化し、夫々胴部１５との境界を画す部分である。
【００１５】
図２は、車両の懸架装置において、軸方向圧縮荷重に対し非線形ばね特性を有する上記の鼓型コイルばね１０を用いた一例を示すもので、後輪用のトーションビームアクスル式サスペンションに適用したものである。図２において、車両（図示せず）の左右の車輪（図示せず）のサスペンションに関し、夫々車両前方の車体に設けられたピボット１と車両後方の車輪の軸２がトレーリングアーム（以下、単にアームという）３で結合されており、更に、左右のアーム３がトーションビーム４によって結合されている。而して、左右のアーム３が各々のピボット１を回転中心として上下方向に揺動し、ニーアクションが行なわれるように構成されている。そして、車体（図示せず）に支持される上側座５と、アーム３に支持される下側座６との間に図１の鼓型コイルばね１０が介装されると共に、車体（図示せず）と軸２との間にショックアブソーバ２０が介装されている。
【００１６】
図３は上記鼓型コイルばね１０の作動状態を示すもので、ＵＳは上側座巻部１１の座面を示し、ＦＢはフルバンプ状態の下側座巻部１２の座面を、ＬＤは積載状態の下側座巻部１２の座面を、ＥＭは空車状態の下側座巻部１２の座面を、そしてＦＲはフルリバウンド状態の下側座巻部１２の座面を、夫々示す。ここで、フルバンプ状態とは最大圧縮状態、即ち鼓型コイルばね１０が最も圧縮された状態であり、積載状態（ＬＡＤＥＮ）とは例えば２名乗車時というように所定重量の積載物が存在する状態である。そして、フルリバウンド状態とは、乗員無の車両をリフトしたとき、車輪の自重によって鼓型コイルばね１０が最も伸長する最大伸長状態であり、走行中に車輪が最も下方に位置する。
【００１７】
ここでは、フルリバウンド状態から空車状態までの間と、積載状態からフルバンプ状態までの間は、ばね定数が一定とされ、夫々前述の第１のばね定数域と第２のばね定数域に相当する。つまり、フルリバウンド状態から空車状態までの間と、積載状態からフルバンプ状態までの間は、自由巻数が一定である。これに対し、空車状態から積載状態（常用）までの間は自由巻数が変化し、前述のばね定数変化域に相当する。
【００１８】
即ち、鼓型コイルばね１０がフルリバウンド状態からフルバンプ状態の間で、上側徐変部１３及び下側徐変部１４は素線間の接触及び座との接触に従って変化するので、自由巻端の位置が移動し、自由巻数（即ち、有効巻数）は徐変（減少）することとなる。特に、鼓型コイルばね１０がフルリバウンド状態にあるときには、鼓型コイルばね１０の上下の自由巻端は夫々、上側座巻部１１と上側徐変部１３との境界及び下側座巻部１２と下側徐変部１４との境界に位置し、鼓型コイルばね１０の自由巻数は上側徐変部１３、胴部１５及び下側徐変部１４の各自由巻数の総和と略等しくなる。これに対し、鼓型コイルばね１０がフルバンプ状態にあるときには上側徐変部１３及び下側徐変部１４が線間接触及び座と接触した状態となるため、鼓型コイルばね１０の上下の自由巻端は夫々、上側徐変部１３と胴部１５との境界及び下側徐変部１４と胴部１５との境界に位置し、鼓型コイルばね１０の自由巻数は胴部１５の巻数と略等しくなる。
【００１９】
そして、本実施形態においては、鼓型コイルばね１０がフルリバウンド状態（第１のばね定数域）にあるときに鼓型コイルばね１０の軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を均等に分割、即ち二等分する第１の中間方向と、鼓型コイルばね１０がフルバンプ状態（第２のばね定数域）にあるときに鼓型コイルばね１０の軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第２の中間方向とを所定の関係に調整すると共に、鼓型コイルばね１０の総自由巻数の小数値を所定の値に設定するように構成されている。これら第１及び第２の中間方向は、図１に示すように、各荷重条件（第１及び第２のばね定数域）において、鼓型コイルばね１０の軸方向上方からみて鼓型コイルばね１０の中心軸と上下の自由巻端とを結ぶ二つの線分（図１に示す上側自由巻端の半径方向及び下側自由巻端の半径方向）がなす角度を二等分する方向を表わしている。
【００２０】
以下、本実施形態に係る鼓型コイルばね１０の具体的態様に関し、種々のサンプルを設定してシミュレーションを行った結果に基づき、自由巻数と横力の関係について説明する。尚、シミュレーション時の各サンプルにおいて、上側座巻部１１及び下側座巻部１２の巻数、上側徐変部１３及び下側徐変部１４の巻数、並びに胴部１５の巻数を変数として６種の態様を設定し、ばね特性及び圧縮条件は以下のように共通の値に設定し、計算には汎用有限要素法コードＡＢＡＱＵＳを使用した。即ち、ばね特性については、第１のばね定数として４２．０Ｎ／ｍｍ及び第２のばね定数として８１．０Ｎ／ｍｍの二つのばね定数を有するものに設定し、取付荷重を３１２５Ｎに設定した（但し、１割程度のバラツキを許容）。圧縮条件については、フルリバウンド状態からフルバンプ状態に至る高さ変化に相当する平行圧縮（軸方向圧縮荷重）とした。以下の説明においては、図４乃至図１０に用いたサンプルについて個々に説明した後に、上記６種の態様をまとめて列挙する。
【００２１】
図４は、鼓型コイルばね１０がフルリバウンド状態にあるときに鼓型コイルばね１０の軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第１の中間方向と、鼓型コイルばね１０がフルバンプ状態にあるときに鼓型コイルばね１０の軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第２の中間方向とを同一の方向に調整して、鼓型コイルばね１０を平行に圧縮したときの荷重、横力の大きさ及び方向を示す。尚、この場合における横力と、その方向は図１１に示すように定義している。即ち、鼓型コイルばね１０を圧縮したときに発生するばね反力の下側座に及ぼす水平成分（図１１に示すばね反力横力成分）を、ここでいう「横力」とする。そして、「横力の方向」は、鼓型コイルばね１０の中心軸から下側端末を基準とした方向（図１１に示す下側端末方向）とばね反力横力成分とがなす角とし、図４の右側の縦軸に「下側端末からの方向」として、下側端末からの巻数（図１１に円弧矢印で示す範囲の巻数）で表わしている。
【００２２】
このときの鼓型コイルばね１０のサンプルは、上側座巻部１１及び下側座巻部１２の巻数が夫々０．５巻、上側徐変部１３及び下側徐変部１４の巻数が夫々１．１巻、そして胴部１５の巻数が３．５巻のもの（総巻数：６．７巻）とした。尚、図４（図５、図８乃至図１０も同様）において、横軸はたわみ量、左側の縦軸は荷重の大きさ、右側の縦軸は横力の方向を表す。そして、２点鎖線が、鼓型コイルばね１０を平行に圧縮したときの垂直荷重の１／１０の値を示し、実線が横力の大きさ、破線が横力の方向を示している。更に、図４（及び図５、図８乃至図１０）の白丸は、車載時における各状態の高さでの、鼓型コイルばね１０の軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する中間方向（上記第１及び第２の中間方向を含み、以下では代表して「自由巻端の中間方向」という）を、鼓型コイルばね１０の軸方向上方からみて下側座巻部１２の端末からの巻数で表わしている。尚、図４、図５、図８乃至図１０において、フルリバウンド状態（ＦＲ）から空車状態（ＥＭ）までの第１のばね定数域をａで示し、空車状態（ＥＭ）から積載状態（ＬＤ）までのばね定数変化域をｂで示し、積載状態（ＬＤ）からフルバンプ状態（ＦＢ）までの第２のばね定数域をｃで示している。
【００２３】
図４から明らかなように、鼓型コイルばね１０がフルリバウンド状態（ＦＲ）、フルバンプ状態（ＦＢ）等の何れの状態にあるときにも、横力の方向は自由巻端の中間方向（破線）から鼓型コイルばね１０の軸方向上方からみて鼓型コイルばね１０の上側に向かって−０．２５巻の方向で、同一の方向になる。この結果は、次に説明する図５の結果と共に、後述する３種のサンプル全てにおいて確認された。
【００２４】
図５は、鼓型コイルばね１０がフルリバウンド状態にあるときの第１の中間方向とフルバンプ状態にあるときの第２の中間方向とが逆方向となるように調整して、鼓型コイルばね１０を平行に圧縮したときの荷重、横力の大きさ及び方向を示す。このときの鼓型コイルばね１０のサンプルは、上側座巻部１１及び下側座巻部１２の巻数が夫々０．５巻、上側徐変部１３及び下側徐変部１４の巻数が夫々１．３巻、そして胴部１５の巻数が３．８巻のもの（総巻数：７．４巻）とした。図５から明らかなように、鼓型コイルばね１０がフルリバウンド状態（ＦＲ）にあるときの横力の方向は自由巻端の中間方向（破線）から鼓型コイルばね１０の軸方向上方からみて鼓型コイルばね１０の上側に向かって−０．２５巻の方向で、フルバンプ状態（ＦＢ）にあるときの横力の方向も自由巻端の中間方向（破線）から−０．２５巻の方向であるが、後者ではフルリバウンド状態にあるときの横力の方向と逆の方向となっている。尚、横力方向は、フルリバウンド状態からフルバンプ状態まで徐々に変化する。
【００２５】
次に、鼓型コイルばね１０の自由巻数と横力の大きさの関係について、図４、図６及び図７を参照して説明する。図４において、フルリバウンド状態（ＦＲ）から空車状態（ＥＭ）までの横力の大きさの変化をΔｆ１とし、積載状態（ＬＤ）からフルバンプ状態（ＦＢ）までの横力の大きさの変化をΔｆ２としたときの、鼓型コイルばね１０の総自由巻数の小数値に対するフルリバウンド状態（ＦＲ）から空車状態（ＥＭ）までの横力の大きさの変化（Δｆ１）を図６に示し、同総自由巻数の小数値に対する積載状態（ＬＤ）からフルバンプ状態（ＦＢ）までの横力の大きさの変化（Δｆ２）を図７に示す。尚、ここでは自由巻数と横力の大きさの関係を明らかにするため、横力の方向が変化しない第１の中間方向と第２の中間方向が同一の方向の鼓型コイルばね１０のシミュレーション結果のみを示している。
【００２６】
図６及び図７から明らかなように、フルリバウンド状態（ＦＲ）から空車状態（ＥＭ）までの横力の大きさの変化（Δｆ１）は、鼓型コイルばね１０の総自由巻数の小数値が０．６５近傍で最大の増加量を示し、０．１５近傍で最小の増加量を示している。また、積載状態（ＬＤ）からフルバンプ状態（ＦＢ）までの横力の大きさの変化（Δｆ２）は、鼓型コイルばね１０の総自由巻数の小数値が０．５近傍で最大の増加量を示し、０．０近傍で最小の増加量を示しており、通常のコイルばねと同様の特性を示している。
【００２７】
結局，図４乃至図７から明らかなように、鼓型コイルばね１０を平行に圧縮したときの鼓型コイルばね１０の自由巻数が横力に与える影響は、先ず、鼓型コイルばね１０がフルリバウンド状態及びフルバンプ状態にあるときの横力の方向は自由巻端の中間方向から、鼓型コイルばね１０の軸方向上方からみて−０．２５巻の方向で、フルリバウンド状態からフルバンプ状態まで徐々に変化する。次に、鼓型コイルばね１０の総自由巻数の小数値が０．５〜０．７近傍で横力が最大の増加量を示し、０．０〜０．２近傍で最小の増加量となる。これらの特性に鑑み横力を適切に調整することができ、以下に説明するように、目標とする仕様に適合し得る荷重特性となる。
【００２８】
先ず、目標とする方向に最大の横力を確保するには、第１に、鼓型コイルばね１０がフルリバウンド状態にあるときに鼓型コイルばね１０の軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第１の中間方向と、鼓型コイルばね１０がフルバンプ状態にあるときに鼓型コイルばね１０の軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第２の中間方向とを同一の方向に調整する。第２に、鼓型コイルばね１０がフルリバウンド状態にあるとき及びフルバンプ状態にあるときの総自由巻数の小数値を略０．５に調整する。第３に、鼓型コイルばね１０がフルリバウンド状態にあるときの自由巻端の中間方向を、目標とする横力方向に対し、鼓型コイルばね１０の軸方向上方からみて鼓型コイルばね１０の上側に向かって＋０．２５巻の方向に調整する。
【００２９】
上記のように調整した鼓型コイルばね１０として、上側座巻部１１及び下側座巻部１２の巻数が夫々０．５巻、上側徐変部１３及び下側徐変部１４の巻数が夫々１．０巻、そして胴部１５の巻数が３．５巻のサンプル（総巻数：６．５巻）を用いた。このサンプルのシミュレーション結果を図８に示すように、（前述の図４及び図５並びに後述の図９及び図１０に比べて）横力が最大の荷重特性を示している。
【００３０】
次に、最小の横力を確保するには、鼓型コイルばね１０がフルリバウンド状態にあるとき及びフルバンプ状態にあるときの総自由巻数の小数値を略０．０に調整すればよく、例えば、上側座巻部１１及び下側座巻部１２の巻数が夫々０．５巻、上側徐変部１３及び下側徐変部１４の巻数が夫々１．１巻、そして胴部１５の巻数が３．９巻のサンプル（総巻数：７．１巻）がある。このサンプルのシミュレーション結果を図９に示すように、（前述の図４、図５及び図８並びに後述の図１０に比べて）横力が最小の荷重特性を示している。
【００３１】
また、たわみ量の増加途中から目標とする方向に横力を増加させるには、第１に、鼓型コイルばね１０がフルリバウンド状態にあるときの総自由巻数の小数値を略０．０に調整する。第２に、鼓型コイルばね１０がフルバンプ状態にあるときの総自由巻数の小数値を略０．５に調整する。第３に、鼓型コイルばね１０がフルバンプ状態にあるときに鼓型コイルばね１０の軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第２の中間方向を、目標とする横力方向に対し、鼓型コイルばね１０の軸方向上方からみて鼓型コイルばね１０の上側に向かって＋０．２５巻の方向に調整する。
【００３２】
上記のように調整した鼓型コイルばね１０として、上側座巻部１１及び下側座巻部１２の巻数が夫々０．５巻、上側徐変部１３及び下側徐変部１４の巻数が夫々１．３巻、そして胴部１５の巻数が３．５巻のサンプル（総巻数：７．１巻）を用いた。このサンプルのシミュレーション結果を図１０に示すように、たわみ量の増加途中から（目標とする方向に）横力が増加する荷重特性を示している。
【００３３】
更に、たわみ量の増加途中から目標とする方向に横力を減少させるには、第１に、鼓型コイルばね１０がフルリバウンド状態にあるときに鼓型コイルばね１０の軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第１の中間方向を、目標とする横力方向に対し、鼓型コイルばね１０の軸方向上方からみて鼓型コイルばね１０の上側に向かって＋０．２５巻の方向に調整する。第２に、上記第１の中間方向と、鼓型コイルばね１０がフルバンプ状態にあるときに鼓型コイルばね１０の軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第２の中間方向とを、逆方向とする。第３に、鼓型コイルばね１０がフルリバウンド状態にあるときの総自由巻数の小数値を略０．５に調整し、第４に、鼓型コイルばね１０がフルバンプ状態にあるときの総自由巻数の小数値を略０．０に調整する。
【００３４】
上記のように調整した鼓型コイルばね１０として、上側座巻部１１及び下側座巻部１２の巻数が夫々０．５巻、上側徐変部１３及び下側徐変部１４の巻数が夫々１．３巻、そして胴部１５の巻数が３．８巻のサンプル（総巻数：７．４巻）を用いた。このサンプルは下側座巻部１２の端末から０．４５巻の方向に横力を生じ、図５に示すように、たわみ量の増加途中から横力が減少する荷重特性となる。
【００３５】
上記図４乃至図１０に用いたサンプルを含む前述の６種の態様を以下に列挙する。先ず、上側座巻部１１及び下側座巻部１２の巻数が夫々０．５巻、上側徐変部１３及び下側徐変部１４の巻数が夫々１．１巻、そして胴部１５の巻数が３．３乃至４．３巻（０．１巻毎に設定）のサンプルを態様Ａとする。また、上側座巻部１１及び下側座巻部１２の巻数が夫々０．５巻、上側徐変部１３及び下側徐変部１４の巻数が夫々０．９乃至１．３巻、そして胴部１５の巻数が３．８巻のサンプルを態様Ｂとする。更に、上側座巻部１１及び下側座巻部１２の巻数が夫々０．５巻、上側徐変部１３及び下側徐変部１４の巻数が夫々０．９乃至１．３巻、そして胴部１５の巻数が３．５巻のサンプルを態様Ｃとする。
【００３６】
前述の図４乃至図１０で使用されたサンプルは上記の態様Ａ乃至Ｃの何れかに包含されている。即ち、図４、図６及び図７では態様Ａ、図５では態様Ｂ、図８では態様Ｃ、図９では態様Ａ、図１０では態様Ｃに、夫々包含されるサンプルの一例である。前述のように、ばね特性については、第１のばね定数が４２．０Ｎ／ｍｍ、第２のばね定数が８１．０Ｎ／ｍｍ、取付荷重が３１２５Ｎというように共通の値に設定され、圧縮条件については、フルリバウンド状態からフルバンプ状態に至る高さ変化に相当する平行圧縮とされている。
【００３７】
尚、図２に示した実施形態は、鼓型コイルばね１０をトーションビームアクスル式サスペンションに適用したものであるが、軸方向圧縮荷重に対し非線形ばね特性を有する懸架コイルばねを必要とする種々の形式のサスペンションに適用可能である。例えば、マルチリンク式サスペンション、後輪用のストラット式サスペンションに対しても、上記の実施形態と同様に適用することができる。
【００３８】
【発明の効果】
本発明は上述のように構成されているので以下の効果を奏する。即ち、請求項１に係る懸架コイルばねは、鼓型コイルばねに対する軸方向圧縮荷重に応じて、その自由巻数が胴部並びに上側徐変部及び下側徐変部の各自由巻数の総和であって一定の値である第１のばね定数域、その自由巻数が変化するばね定数変化域、及びその自由巻数が胴部の自由巻数と略等しい一定の値である第２のばね定数域の何れかの状態となり、鼓型コイルばねが第１のばね定数域にあるときに軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第１の中間方向と、鼓型コイルばねが第２のばね定数域にあるときに軸方向上方からみて上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第２の中間方向とを所定の関係に調整すると共に、鼓型コイルばねの総自由巻数の小数値を所定の値に設定することとしたものであり、横力の方向及び大きさを所望の方向及び値に調整することができるので、所期のばね特性を容易に確保することができる。
【００３９】
前記懸架コイルばねにおいて、請求項２に記載のように構成すれば、容易に横力を最大値に調整することができる。更に、請求項３に記載のように構成すれば、容易に横力を最大値に調整すると共に、目標とする方向に調整することができる。また、請求項４に記載のように構成すれば、容易に横力を最小値に調整することができる。
【００４０】
更に、請求項５に記載のように構成すれば、前記鼓型コイルばねのたわみ量の増加途中から目標とする方向に横力を増加する特性に調整することができる。あるいは、請求項６に記載のように構成すれば、前記鼓型コイルばねのたわみ量の増加途中から目標とする方向に横力を減少する特性に調整することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る鼓型コイルばねを示す斜視図である。
【図２】本発明の一実施形態に係る鼓型コイルばねを備えた車両の懸架装置を示す斜視図である。
【図３】本発明の一実施形態における鼓型コイルばねの作動状態を示す説明図である。
【図４】本発明の一実施形態に係る鼓型コイルばねがフルリバウンド状態にあるときに上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第１の中間方向と、鼓型コイルばねがフルバンプ状態にあるときに上下の自由巻端の半径方向間に存在する自由巻小数部を二等分する第２の中間方向とを同一の方向に調整して、鼓型コイルばねを平行に圧縮したときの荷重、横力の大きさ及び方向を示すグラフである。
【図５】本発明の一実施形態に係る鼓型コイルばねがフルリバウンド状態にあるときの第１の中間方向とフルバンプ状態にあるときの第２の中間方向とが逆方向となるように調整して、鼓型コイルばねを平行に圧縮したときの荷重、横力の大きさ及び方向を示すグラフである。
【図６】本発明の一実施形態に係る鼓型コイルばねの総自由巻数の小数値に対する、フルリバウンド状態（ＦＲ）から空車状態（ＥＭ）までの横力の大きさの変化を示すグラフである。
【図７】本発明の一実施形態に係る鼓型コイルばねの総自由巻数の小数値に対する、積載状態（ＬＤ）からフルバンプ状態（ＦＢ）までの横力の大きさの変化を示すグラフである。
【図８】本発明の一実施形態において、目標とする方向に最大の横力を確保するときの鼓型コイルばねの荷重特性を示すグラフである。
【図９】本発明の一実施形態において、最小の横力を確保するときの鼓型コイルばねの荷重特性を示すグラフである。
【図１０】本発明の一実施形態において、たわみ量の増加途中から目標とする方向に横力を増加させるときの鼓型コイルばねの荷重特性を示すグラフである。
【図１１】本発明の一実施形態に係る鼓型コイルばねにおける、横力とその方向の関係を示す斜視図である。
【符号の説明】
１ピボット，２軸，３アーム，４トーションビーム，
５上側座，６下側座，１０鼓型コイルばね，１１上側座巻部，
１２下側座巻部，１３上側徐変部，１４下側徐変部，１５胴部，
２０ショックアブソーバ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a suspension coil spring used for a suspension system of a vehicle, and more particularly to a suspension coil spring having a non-linear spring characteristic with respect to an axial compression load.
[0002]
[Prior art]
Various types of vehicle suspensions are known, and it is intended to adjust the characteristics to meet various requirements. For example, in order to change the number of turns of the effective winding portion in accordance with the load, various suspension coil springs have been proposed which adjust the pitch, the coil diameter, the wire diameter, and the like, and have a non-linear spring characteristic with respect to an axial compression load. As such a non-linear coil spring, for example, the barrel has a barrel shape having a maximum diameter, and the wire at both ends is cut so that the wire diameter of the coil wire gradually decreases from the axial center toward both ends. Special coil springs have been proposed.
[0003]
Further, the spring characteristics required for a suspension that performs knee action are also non-linear, and a trailing arm type suspension is known for rear wheels. In this technique, a pivot disposed in front of a vehicle and an axle of rear wheels are connected by an arm, and swing vertically about the pivot to perform a so-called knee action, which is disclosed in, for example, Patent Documents 1 and 2 below. Have been. This suspension structure is composed of a suspension link for suspending wheels and a shock absorber for cushioning the movement of bumps and rebounds of the wheels. However, both Patent Documents 1 and 2 mention the constitution of the suspension coil spring. Not.
[0004]
[Patent Document 1]
JP-A-2002-46443
[Patent Document 2]
JP-A-8-268018
[0005]
[Problems to be solved by the invention]
In the above-mentioned special coil spring, it is not easy to form such that the wire diameters at both ends are gradually reduced, so that it is not suitable for mass production and inevitably becomes expensive. Therefore, it is desired to secure desired nonlinear characteristics without changing at least the wire diameter. A drum-shaped compression coil spring, that is, a drum-shaped coil spring is effective as a suspension coil spring that can meet such a demand. This hourglass-shaped coil spring has an upper end turn part and a lower end turn part, and an upper gradually changing part and a lower end part whose outer diameter gradually decreases from the upper end turn part and the lower end turn part toward the center in the axial direction, respectively. Equipped with a gradually changing part and a body part of approximately the same diameter that is continuous with the minimum diameter part of the upper and lower gradually changing parts, the outer shape shows a drum shape, and the desired nonlinear characteristics can be easily set. can do. In particular, in a vehicle suspension system, a suspension coil spring which can be adjusted to a desired (magnitude and / or direction) lateral force is desired, and a drum-shaped coil spring is preferable.
[0006]
Therefore, an object of the present invention is to provide a suspension coil spring having a non-linear spring characteristic with respect to an axial compression load, which can be adjusted to a desired lateral force by using a drum-shaped coil spring.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention provides an upper end turn portion and a lower end turn portion, and an upper end turn portion and a lower end turn portion directed toward an axial center from the upper end turn portion and the lower end turn portion, respectively. From a drum-shaped coil spring having an upper gradual change portion and a lower gradual change portion in which the outer diameter gradually decreases, and a body portion having substantially the same diameter continuing to the minimum diameter portion of the upper gradual change portion and the lower gradual change portion. In accordance with the axial compression load on the drum-shaped coil spring, the number of free turns of the drum-shaped coil spring is the sum of the respective free turns of the trunk and the upper gradually changing portion and the lower gradually changing portion, and is constant. , A spring constant change region in which the number of free turns of the drum coil spring changes, and a constant value in which the number of free turns of the drum coil spring is substantially equal to the number of free turns of the body. In a suspension coil spring that is in any state of a certain second spring constant range, the hourglass coil spring is A first intermediate direction which bisects a free winding fraction present between the upper and lower free winding ends in the radial direction when viewed from above in the axial direction of the drum-shaped coil spring when in the spring constant range; A second intermediate portion that bisects a free winding fraction existing between the upper and lower free winding ends in the radial direction when viewed from above in the axial direction of the hourglass-shaped coil spring when the coil spring is in the second spring constant range; The direction is adjusted to have a predetermined relationship, and the decimal value of the total number of free turns of the drum-shaped coil spring is set to a predetermined value.
[0008]
The upper gradual change portion and the lower gradual change portion demarcate the upper end turn portion and the lower end turn portion, respectively, when the hourglass coil spring is in the first spring constant range. Are in the second spring constant range, and are in contact with the line contact or the seat, respectively, are integrated with the upper end turn portion and the lower end turn portion, respectively, and are portions that define the boundaries with the body, respectively. The free winding end moves in accordance with the line contact or the contact with the seat. Then, a region between the first spring constant region and the second spring constant region is a spring constant change region. Thereby, the direction and magnitude of the lateral force can be adjusted to desired directions and values.
[0009]
The suspension coil spring according to claim 1, wherein the first intermediate direction and the second intermediate direction coincide with each other, and the drum-shaped coil spring is connected to the first coil spring. If the decimal values of the total number of free turns of the drum-shaped coil spring in the spring constant range and the second spring constant range are set to approximately 0.5, the lateral force is adjusted to the maximum value. be able to. In particular, in the suspension coil spring according to claim 2, as set forth in claim 3, a target in which the first and second intermediate directions are set by the number of turns from a terminal of the lower end turn. If the direction is set to +0.25 turns toward the upper side of the hourglass coil spring when viewed from above in the axial direction of the hourglass coil spring with respect to the lateral force direction, the lateral force is adjusted to the maximum value. Can be adjusted in the target direction.
[0010]
Alternatively, in the suspension coil spring according to claim 1, as in claim 4, the drum when the drum-shaped coil spring is in the first spring constant region and the second spring constant region. If the decimal value of the total number of free turns of the type coil spring is set to approximately 0.0, the lateral force can be adjusted to the minimum value.
[0011]
Further, in the suspension coil spring according to the first aspect, as described in the fifth aspect, when the hourglass-shaped coil spring is in the first spring constant range, the decimal value of the total free winding number is set to approximately 0. 0, the decimal value of the total number of free turns when the hourglass coil spring is in the second spring constant range is set to approximately 0.5, and the second intermediate direction is set to the lower side. Setting the direction of +0.25 turns toward the upper side of the hourglass coil spring as viewed from above the axial direction of the hourglass coil spring with respect to the target lateral force direction set by the number of windings from the end of the end winding section; Then, the lateral force can be increased in the target direction while the deflection of the drum-shaped coil spring is increasing.
[0012]
Alternatively, in the suspension coil spring according to the first aspect, as described in the sixth aspect, the first intermediate direction is set in a target lateral force direction set by the number of turns from a terminal of the lower end turn. On the other hand, when viewed from above in the axial direction of the hourglass coil spring, the direction is set to +0.25 turns toward the upper side of the hourglass coil spring, and the first intermediate direction and the second intermediate direction are reversed. Direction, and the decimal value of the total number of free turns when the drum-shaped coil spring is in the first spring constant range is set to approximately 0.5, and the drum-shaped coil spring is connected to the second spring. By setting the decimal value of the total number of free turns in the constant range to approximately 0.0, the lateral force can be reduced in the target direction while the amount of deflection of the hourglass coil spring is increasing. .
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 relates to an embodiment of a drum-shaped coil spring provided for a suspension coil spring of the present invention, and shows a state before mounting on a suspension device. As shown in a schematic range on the right side of FIG. 1, a drum-shaped coil spring 10 of the present embodiment includes an upper end turn 11 and a lower end turn 12 and an upper end turn 11 and a lower end turn. The upper gradual change portion 13 and the lower gradual change portion 14 whose outer diameters gradually decrease from 12 toward the center in the axial direction, respectively. It is formed in a drum shape with a trunk 15 having a diameter, and has a non-linear spring characteristic against an axial compressive load.
[0014]
That is, in accordance with the axial compression load, the number of free turns of the drum-shaped coil spring 10 is the sum of the number of free turns of the body portion 15 and the upper gradually changing portion 13 and the lower gradually changing portion 14 and is a constant value. A second spring in which the spring constant region of 1, the spring constant change region in which the number of free turns of the drum coil spring 10 changes, and the free number of turns of the drum coil spring 10 is a constant value substantially equal to the number of free turns of the body portion 15. One of the states in the constant range. Therefore, the upper gradual change portion 13 and the lower gradual change portion 14 delimit the upper end turn portion 11 and the lower end turn portion 12, respectively, when the drum-shaped coil spring 10 is in the first spring constant range. When the drum-shaped coil spring 10 is in the second spring constant range, it comes into contact with the line or the seat to be integrated with the upper end turn 11 and the lower end turn 12, respectively, and the boundary with the body 15 respectively. It is the part that draws.
[0015]
FIG. 2 shows an example in which the above-described drum-shaped coil spring 10 having a non-linear spring characteristic with respect to an axial compressive load is used in a vehicle suspension system, and is applied to a torsion beam axle type suspension for a rear wheel. is there. In FIG. 2, regarding a suspension of left and right wheels (not shown) of a vehicle (not shown), a pivot 1 provided on a vehicle body in front of the vehicle and a shaft 2 of wheels in rear of the vehicle are respectively connected to a trailing arm (hereinafter simply referred to as a "trailing arm"). The left and right arms 3 are connected by a torsion beam 4. Thus, the left and right arms 3 are configured to swing up and down around the respective pivots 1 to perform knee action. A drum-shaped coil spring 10 shown in FIG. 1 is interposed between an upper seat 5 supported by a vehicle body (not shown) and a lower seat 6 supported by the arm 3. ) And the shaft 2 are provided with a shock absorber 20.
[0016]
FIG. 3 shows an operation state of the drum-shaped coil spring 10. US shows a seat surface of the upper end turn portion 11, FB denotes a seat surface of the lower end turn portion 12 in a full bump state, and LD denotes a loaded state. , EM indicates a seat surface of the lower end turn portion 12 in an empty state, and FR indicates a seat surface of the lower end turn portion 12 in a full rebound state. Here, the full bump state is a maximum compression state, that is, a state in which the drum-shaped coil spring 10 is most compressed, and the loading state (LADEN) is a state in which a load having a predetermined weight exists, for example, when two passengers are riding. It is. The full rebound state is a maximum extension state in which the hourglass-shaped coil spring 10 is extended most by its own weight when a vehicle without an occupant is lifted, and the wheel is located at the lowest position during traveling.
[0017]
Here, the spring constant is constant between the full rebound state and the empty vehicle state and between the loaded state and the full bump state, and corresponds to the first spring constant area and the second spring constant area, respectively. . That is, the number of free turns is constant between the full rebound state and the empty state and between the loaded state and the full bump state. On the other hand, the number of free windings changes from the empty state to the loaded state (normal use), which corresponds to the above-mentioned spring constant change range.
[0018]
That is, the upper gradual change portion 13 and the lower gradual change portion 14 change between the full rebound state and the full bump state according to the contact between the strands and the contact with the seat. The position moves, and the number of free turns (that is, the effective number of turns) gradually changes (decreases). In particular, when the drum-shaped coil spring 10 is in the full rebound state, the upper and lower free winding ends of the drum-shaped coil spring 10 are respectively at the boundary between the upper end turn portion 11 and the upper gradually changing portion 13 and the lower end turn portion 12. The number of free turns of the drum-shaped coil spring 10 is substantially equal to the sum of the respective free turns of the upper gradual change portion 13, the body portion 15, and the lower gradual change portion 14. On the other hand, when the drum-shaped coil spring 10 is in the full bump state, the upper gradually changing portion 13 and the lower gradually changing portion 14 are in a state of contact between the line and the seat, so that the upper and lower free movement of the drum-shaped coil spring 10 is possible. The winding ends are respectively located at the boundary between the upper gradually changing portion 13 and the body portion 15 and at the boundary between the lower gradually changing portion 14 and the body portion 15. The number of free turns of the drum-shaped coil spring 10 is the number of turns of the body portion 15. It is almost equal.
[0019]
In the present embodiment, when the hourglass-shaped coil spring 10 is in a full rebound state (first spring constant range), when viewed from above the axial direction of the hourglass-shaped coil spring 10, between the upper and lower free winding ends in the radial direction. The first intermediate direction in which the existing free winding fraction part is equally divided, ie, bisected, and the axis of the drum-shaped coil spring 10 when the drum-shaped coil spring 10 is in a full bump state (second spring constant range). The direction of the free winding fraction present between the upper and lower free winding ends in the radial direction when viewed from above is adjusted in a predetermined relationship with a second intermediate direction, and the total free winding of the drum-shaped coil spring 10 is adjusted. The decimal value is set to a predetermined value. As shown in FIG. 1, the first and second intermediate directions are different from each other in each load condition (first and second spring constant ranges) when viewed from above the drum-shaped coil spring 10 in the axial direction. Represents a direction bisecting an angle formed by two line segments (the radial direction of the upper free winding end and the radial direction of the lower free winding end shown in FIG. 1) connecting the center axis of the upper and lower free winding ends. I have.
[0020]
Hereinafter, the relationship between the number of free turns and the lateral force will be described based on the results of simulations performed by setting various samples for the specific configuration of the drum-shaped coil spring 10 according to the present embodiment. In each of the samples at the time of the simulation, the number of turns of the upper end turn part 11 and the lower end turn part 12, the number of turns of the upper gradual change part 13 and the lower gradual change part 14, and the number of turns of the body part 15 were set to six types Was set, the spring characteristics and compression conditions were set to common values as follows, and a general purpose finite element method code ABAQUS was used for the calculation. That is, the spring characteristics were set to those having two spring constants of 42.0 N / mm as the first spring constant and 81.0 N / mm as the second spring constant, and the mounting load was set to 3125 N ( However, variation of about 10% is allowed). The compression conditions were parallel compression (axial compression load) corresponding to a change in height from a full rebound state to a full bump state. In the following description, the samples used in FIGS. 4 to 10 are individually described, and then the above-described six embodiments are collectively listed.
[0021]
FIG. 4 is a diagram showing a second half of the free winding fraction that exists between the upper and lower free winding ends in the radial direction when viewed from above the axial direction of the hourglass coil spring 10 when the hourglass coil spring 10 is in a full rebound state. 1 and the free winding fraction present between the upper and lower free winding ends in the radial direction when viewed from above the axial direction of the hourglass coil spring 10 when the hourglass coil spring 10 is in the full bump state. The magnitude and direction of the load and lateral force when the drum-shaped coil spring 10 is compressed in parallel by adjusting the second intermediate direction to the same direction are shown. The lateral force and the direction in this case are defined as shown in FIG. That is, the horizontal component (spring reaction force lateral force component shown in FIG. 11) exerted on the lower seat of the spring reaction force generated when the drum-shaped coil spring 10 is compressed is referred to as “lateral force” here. The “direction of the lateral force” is an angle formed by a direction from the center axis of the drum-shaped coil spring 10 with respect to the lower terminal (the lower terminal direction shown in FIG. 11) and a spring reaction force lateral force component, The vertical axis on the right side of FIG. 4 indicates the number of turns from the lower terminal (the number of turns in the range indicated by the arc arrow in FIG. 11) as “direction from the lower terminal”.
[0022]
At this time, the sample of the drum-shaped coil spring 10 is such that the number of turns of the upper end turn portion 11 and the lower end turn portion 12 is 0.5, and the number of turns of the upper gradually changing portion 13 and the lower gradually changing portion 14 is 1 respectively. 1. The number of turns of the body 15 was 3.5 and the number of turns of the body 15 was 3.5 (total number of turns: 6.7). In FIG. 4 (the same applies to FIGS. 5, 8 to 10), the horizontal axis represents the amount of deflection, the left vertical axis represents the magnitude of the load, and the right vertical axis represents the direction of the lateral force. The two-dot chain line indicates the value of 1/10 of the vertical load when the hourglass coil spring 10 is compressed in parallel, the solid line indicates the magnitude of the lateral force, and the broken line indicates the direction of the lateral force. Further, the white circles in FIG. 4 (and FIG. 5, FIGS. 8 to 10) indicate the distance between the upper and lower free winding ends in the radial direction when viewed from the upper side in the axial direction of the drum-shaped coil spring 10 at the height of each state when mounted on the vehicle. An intermediate direction (including the first and second intermediate directions, hereinafter referred to as an “intermediate direction of the free winding end”) that bisects the free winding decimal part existing in the It is represented by the number of turns from the terminal of the lower end winding portion 12 when viewed from above in the axial direction. In FIGS. 4, 5, 8 to 10, the first spring constant range from the full rebound state (FR) to the empty state (EM) is indicated by a, and the first spring constant area is changed from the empty state (EM) to the loaded state (LD). ) Is indicated by b, and the second spring constant area from the loaded state (LD) to the full bump state (FB) is indicated by c.
[0023]
As is clear from FIG. 4, when the drum-shaped coil spring 10 is in any state such as a full rebound state (FR) and a full bump state (FB), the direction of the lateral force is the intermediate direction of the free winding end (broken line). ), The direction is -0.25 turns toward the upper side of the drum-shaped coil spring 10 when viewed from above in the axial direction of the drum-shaped coil spring 10, which is the same direction. This result was confirmed in all three types of samples described later together with the result of FIG. 5 described below.
[0024]
FIG. 5 shows a configuration in which the first intermediate direction when the drum-shaped coil spring 10 is in the full rebound state and the second intermediate direction when the drum-shaped coil spring 10 is in the full bump state are opposite to each other. 10 shows the magnitude and direction of the load and lateral force when 10 is compressed in parallel. At this time, the sample of the drum-shaped coil spring 10 is such that the number of turns of the upper end turn portion 11 and the lower end turn portion 12 is 0.5, and the number of turns of the upper gradually changing portion 13 and the lower gradually changing portion 14 is 1 respectively. The number of turns was 0.3 and the body 15 had 3.8 turns (total number of turns: 7.4). As is clear from FIG. 5, the direction of the lateral force when the drum-shaped coil spring 10 is in the full rebound state (FR) is viewed from above the axial direction of the drum-shaped coil spring 10 from the middle direction (broken line) of the free winding end. In the direction of -0.25 turns toward the upper side of the drum-shaped coil spring 10, the direction of the lateral force when in the full bump state (FB) is -0.25 turns from the middle direction of the free winding end (broken line). However, in the latter case, the direction is opposite to the direction of the lateral force in the full rebound state. Note that the lateral force direction gradually changes from the full rebound state to the full bump state.
[0025]
Next, the relationship between the number of free turns of the drum-shaped coil spring 10 and the magnitude of the lateral force will be described with reference to FIGS. 4, 6, and 7. FIG. In FIG. 4, a change in the magnitude of the lateral force from the full rebound state (FR) to the empty state (EM) is Δf1, and a change in the lateral force from the loaded state (LD) to the full bump state (FB) is shown in FIG. FIG. 6 shows a change (Δf1) in the magnitude of the lateral force from the full rebound state (FR) to the empty state (EM) with respect to the decimal value of the total number of free turns of the drum coil spring 10 when Δf2 is set. FIG. 7 shows a change (Δf2) in the magnitude of the lateral force from the loaded state (LD) to the full bump state (FB) with respect to the decimal value of the total free winding number. Here, in order to clarify the relationship between the number of free turns and the magnitude of the lateral force, a simulation of the drum-shaped coil spring 10 in which the first intermediate direction and the second intermediate direction in which the direction of the lateral force does not change is the same. Only the results are shown.
[0026]
As is clear from FIGS. 6 and 7, the change (Δf1) in the magnitude of the lateral force from the full rebound state (FR) to the empty state (EM) is determined by the decimal value of the total number of free turns of the drum coil spring 10. The maximum increase is shown near 0.65, and the minimum increase is shown near 0.15. The change (Δf2) in the magnitude of the lateral force from the loaded state (LD) to the full bump state (FB) is the largest increase when the decimal value of the total free turns of the drum coil spring 10 is around 0.5. , The minimum increase is shown near 0.0, and the characteristics are the same as those of a normal coil spring.
[0027]
After all, as apparent from FIGS. 4 to 7, the influence of the number of free turns of the drum-shaped coil spring 10 on the lateral force when the drum-shaped coil spring 10 is compressed in parallel is as follows. The direction of the lateral force in the rebound state and the full bump state is gradually from the full rebound state to the full bump state in the direction of -0.25 turns when viewed from above the axial direction of the hourglass coil spring 10 from the middle direction of the free winding end. Changes to Next, when the decimal value of the total number of free turns of the drum-shaped coil spring 10 is in the vicinity of 0.5 to 0.7, the lateral force shows the largest increase, and in the vicinity of 0.0 to 0.2, it becomes the smallest increase. . In view of these characteristics, the lateral force can be appropriately adjusted, and as described below, the load characteristics can be adapted to target specifications.
[0028]
First, in order to ensure the maximum lateral force in the target direction, first, when the drum-shaped coil spring 10 is in the full rebound state, the upper and lower free winding ends as viewed from above the drum-shaped coil spring 10 in the axial direction. A first intermediate direction that bisects the free winding fraction that exists between the radial directions of the first and second free windings when viewed from above the axial direction of the hourglass coil spring 10 when the hourglass coil spring 10 is in a full bump state. The second intermediate direction, which bisects the free winding fraction present between the ends in the radial direction, is adjusted in the same direction. Second, the decimal value of the total number of free turns when the drum-shaped coil spring 10 is in the full rebound state and the full bump state is adjusted to approximately 0.5. Third, the intermediate direction of the free winding end when the hourglass coil spring 10 is in a full rebound state is viewed from the axially upper side of the hourglass coil spring 10 with respect to the target lateral force direction. In the direction of +0.25 turns toward the upper side.
[0029]
As the drum-shaped coil spring 10 adjusted as described above, the number of turns of the upper end turn portion 11 and the lower end turn portion 12 is 0.5, and the number of turns of the upper gradually changing portion 13 and the lower gradually changing portion 14 is respectively. A sample having 1.0 turns and 3.5 turns of the body 15 (total turns: 6.5) was used. As shown in the simulation result of this sample in FIG. 8, the lateral force shows the maximum load characteristic (compared to FIGS. 4 and 5 described above and FIGS. 9 and 10 described later).
[0030]
Next, in order to secure the minimum lateral force, the decimal value of the total free winding number when the drum-shaped coil spring 10 is in the full rebound state and in the full bump state may be adjusted to approximately 0.0. The number of turns of the upper end turn portion 11 and the lower end turn portion 12 is 0.5, respectively, the number of turns of the upper gradually changing portion 13 and the lower gradually changing portion 14 is 1.1, and the number of turns of the body portion 15 is 1.1. There are 3.9 samples (total number of turns: 7.1). As shown in FIG. 9, a simulation result of this sample shows a load characteristic with a minimum lateral force (compared to FIGS. 4, 5, and 8 described above and FIG. 10 described later).
[0031]
In order to increase the lateral force in the target direction while the deflection amount is increasing, first, the decimal value of the total number of free windings when the drum-shaped coil spring 10 is in the full rebound state is reduced to approximately 0.0. adjust. Second, the decimal value of the total number of free turns when the drum-shaped coil spring 10 is in the full bump state is adjusted to approximately 0.5. Third, when the drum-shaped coil spring 10 is in the full bump state, the free winding fraction that exists between the upper and lower free winding ends in the radial direction as viewed from above in the axial direction of the drum-shaped coil spring 10 is bisected. Is adjusted in the direction of +0.25 turns toward the upper side of the hourglass coil spring 10 when viewed from above the axial direction of the hourglass coil spring 10 with respect to the target lateral force direction.
[0032]
As the drum-shaped coil spring 10 adjusted as described above, the number of turns of the upper end turn portion 11 and the lower end turn portion 12 is 0.5, and the number of turns of the upper gradually changing portion 13 and the lower gradually changing portion 14 is respectively. A sample having 1.3 turns and 3.5 turns of the body 15 (total turns: 7.1 turns) was used. As shown in FIG. 10, a simulation result of this sample shows a load characteristic in which the lateral force increases (in the target direction) while the deflection amount is increasing.
[0033]
Further, in order to reduce the lateral force in the target direction while the deflection amount is increasing, firstly, when the drum-shaped coil spring 10 is in the full rebound state, when the drum-shaped coil spring 10 is viewed from above in the axial direction, The first intermediate direction which bisects the free winding fraction present between the free winding ends in the radial direction of the free winding end is viewed from the upper side in the axial direction of the drum coil spring 10 with respect to the target lateral force direction. Adjust in the direction of +0.25 turns toward the upper side of the spring 10. Second, the number of free windings existing between the first intermediate direction and the radial direction of the upper and lower free winding ends when viewed from above in the axial direction of the drum-shaped coil spring 10 when the drum-shaped coil spring 10 is in the full bump state. The second intermediate direction that bisects the part is defined as the opposite direction. Third, the fractional value of the total number of free turns when the drum coil spring 10 is in the full rebound state is adjusted to approximately 0.5. Fourth, the total freedom when the drum coil spring 10 is in the full bump state. Adjust the decimal value of the number of turns to approximately 0.0.
[0034]
As the drum-shaped coil spring 10 adjusted as described above, the number of turns of the upper end turn portion 11 and the lower end turn portion 12 is 0.5, and the number of turns of the upper gradually changing portion 13 and the lower gradually changing portion 14 is respectively. A sample having 1.3 turns and 3.8 turns of the body portion 15 (total turns: 7.4 turns) was used. In this sample, a lateral force is generated in the direction of 0.45 turns from the end of the lower end winding portion 12, and as shown in FIG. 5, the load characteristic is such that the lateral force decreases while the amount of deflection increases.
[0035]
The above-described six embodiments including the samples used in FIGS. 4 to 10 are listed below. First, the number of turns of the upper end turn portion 11 and the lower end turn portion 12 is 0.5, the number of turns of the upper gradually changing portion 13 and the lower gradually changing portion 14 is 1.1, respectively, and the number of turns of the body portion 15. A sample of 3.3 to 4.3 volumes (set for each 0.1 volume) is referred to as mode A. The number of turns of the upper end turn portion 11 and the lower end turn portion 12 is 0.5, respectively, the number of turns of the upper gradually changing portion 13 and the lower gradually changing portion 14 is 0.9 to 1.3, respectively. A sample in which the number of turns of the part 15 is 3.8 is referred to as a mode B. Further, the number of turns of the upper end turn portion 11 and the lower end turn portion 12 is 0.5, respectively, the number of turns of the upper gradually changing portion 13 and the lower gradually changing portion 14 is 0.9 to 1.3, respectively. A sample in which the number of turns of the part 15 is 3.5 is referred to as a mode C.
[0036]
The samples used in FIGS. 4 to 10 described above are included in any of the above aspects A to C. That is, FIG. 4, FIG. 6 and FIG. 7 show examples of samples included in the mode A, the mode B in FIG. 5, the mode C in FIG. 8, the mode A in FIG. 9, and the mode C in FIG. As described above, the spring characteristics are set to common values such that the first spring constant is 42.0 N / mm, the second spring constant is 81.0 N / mm, and the mounting load is 3125 N. Is set to a parallel compression corresponding to a height change from a full rebound state to a full bump state.
[0037]
In the embodiment shown in FIG. 2, the drum-shaped coil spring 10 is applied to a torsion beam axle type suspension. However, various types requiring a suspension coil spring having a non-linear spring characteristic with respect to an axial compression load are used. It is applicable to the suspension. For example, the present invention can be applied to a multi-link type suspension and a strut type suspension for a rear wheel in the same manner as in the above embodiment.
[0038]
【The invention's effect】
The present invention has the following effects because it is configured as described above. That is, in the suspension coil spring according to claim 1, the number of free windings is the sum of the number of free windings of the body, the upper gradually changing portion, and the lower gradually changing portion in accordance with the axial compression load on the hourglass coil spring. Any one of a first spring constant range in which the free winding number changes, and a second spring constant range in which the free winding number has a constant value substantially equal to the free winding number of the body. When the hourglass coil spring is in the first spring constant range, the first intermediate portion that bisects the free winding fraction that exists between the upper and lower free winding ends in the radial direction when viewed from above in the axial direction. And a second intermediate direction which bisects a free winding fraction present between the upper and lower free winding ends in the radial direction when viewed from above in the axial direction when the hourglass coil spring is in the second spring constant range. Is adjusted to a predetermined relationship, and the decimal value of the total number of free turns of the drum coil spring is Is obtained by the setting to a constant value, it is possible to adjust the direction and magnitude of the lateral force in a desired direction and value, can be easily ensured a desired spring characteristic.
[0039]
In the suspension coil spring, when configured as described in claim 2, the lateral force can be easily adjusted to the maximum value. Further, according to the structure described in claim 3, the lateral force can be easily adjusted to the maximum value and the target force can be adjusted in the target direction. Further, according to the structure described in claim 4, the lateral force can be easily adjusted to the minimum value.
[0040]
Further, according to the fifth aspect, it is possible to adjust the characteristic such that the lateral force is increased in a target direction while the amount of deflection of the hourglass coil spring is increasing. Alternatively, with the configuration as described in claim 6, it is possible to adjust the characteristic such that the lateral force decreases in the target direction while the amount of deflection of the hourglass coil spring is increasing.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a drum-shaped coil spring according to an embodiment of the present invention.
FIG. 2 is a perspective view showing a vehicle suspension provided with a drum-shaped coil spring according to one embodiment of the present invention.
FIG. 3 is an explanatory diagram showing an operation state of a drum-shaped coil spring according to an embodiment of the present invention.
FIG. 4 is a first intermediate direction for bisecting a free winding fraction existing between upper and lower free winding ends in a radial direction when a drum-shaped coil spring according to an embodiment of the present invention is in a full rebound state; And the second intermediate direction, which bisects the free winding fraction that exists between the upper and lower free winding ends in the radial direction when the drum coil spring is in the full bump state, is adjusted in the same direction. It is a graph which shows the magnitude | size of load and lateral force when a type coil spring is compressed in parallel.
FIG. 5 is adjusted so that the first intermediate direction when the hourglass-shaped coil spring according to the embodiment of the present invention is in a full rebound state and the second intermediate direction when it is in a full bump state are opposite directions. 4 is a graph showing the magnitude and direction of the load and lateral force when the drum-shaped coil spring is compressed in parallel.
FIG. 6 is a graph showing a change in the magnitude of a lateral force from a full rebound state (FR) to an empty state (EM) with respect to a decimal value of the total number of free turns of the drum-shaped coil spring according to one embodiment of the present invention. is there.
FIG. 7 is a graph showing a change in a magnitude of a lateral force from a loaded state (LD) to a full bump state (FB) with respect to a decimal value of a total free winding number of the drum-shaped coil spring according to one embodiment of the present invention. .
FIG. 8 is a graph showing a load characteristic of a drum-shaped coil spring when a maximum lateral force is secured in a target direction in one embodiment of the present invention.
FIG. 9 is a graph showing load characteristics of a drum-shaped coil spring when a minimum lateral force is secured in one embodiment of the present invention.
FIG. 10 is a graph showing a load characteristic of a drum-shaped coil spring when a lateral force is increased in a target direction while the amount of deflection is increasing in one embodiment of the present invention.
FIG. 11 is a perspective view showing a relationship between a lateral force and a direction thereof in a drum-shaped coil spring according to an embodiment of the present invention.
[Explanation of symbols]
1 pivot, 2 axes, 3 arms, 4 torsion beam,
5 Upper seat, 6 Lower seat, 10 Hour-shaped coil spring, 11 Upper winding part,
12 lower end winding part, 13 upper gradually changing part, 14 lower gradually changing part, 15 trunk,
20 Shock absorber

Claims

An upper end turn portion and a lower end turn portion, an upper gradual change portion and a lower gradual change portion whose outer diameters gradually decrease from the upper end turn portion and the lower end turn portion toward the axial center, respectively; A drum-shaped coil spring having a body part having substantially the same diameter that is continuous with the minimum diameter part of the gradually changing part and the lower gradually changing part, and the drum-shaped coil is provided in accordance with an axial compression load on the drum-shaped coil spring. The first spring constant range, in which the free winding number of the spring is a sum of the free winding numbers of the body portion and the upper gradually changing portion and the lower gradually changing portion and is a constant value, the free winding number of the drum-shaped coil spring is A variable spring constant changing region, and a suspension coil spring in any state of a second spring constant region in which the number of free turns of the drum-shaped coil spring is a constant value substantially equal to the number of free turns of the body portion. When the hourglass coil spring is in the first spring constant range, whether it is axially above the hourglass coil spring or not. A first intermediate direction which bisects a free winding fraction present between upper and lower free winding ends in a radial direction, and the hourglass coil when the hourglass coil spring is in the second spring constant range. A predetermined relationship is established between a free intermediate part that divides the free winding fraction part present between the upper and lower free winding ends in the radial direction when viewed from above the spring in a predetermined relationship, A suspension coil spring, wherein a decimal value of the number of free turns is set to a predetermined value.

The first intermediate direction and the second intermediate direction are made to coincide with each other, and the total of the hourglass coil spring when the hourglass coil spring is in the first spring constant region and the second spring constant region 2. The suspension coil spring according to claim 1, wherein the fractional values of the number of free turns are each set to approximately 0.5.

The first and second intermediate directions are above the hourglass coil spring when viewed from above the axial direction of the hourglass coil spring with respect to a target lateral force direction set by the number of turns from the terminal of the lower end winding section. 3. The suspension coil spring according to claim 2, wherein the direction is set to +0.25 turns toward.

When the drum-shaped coil spring is in the first spring constant region and the second spring constant region, the decimal value of the total free winding number of the drum-shaped coil spring is set to approximately 0.0, respectively. The suspension coil spring according to claim 1.

The fractional value of the total number of free turns when the hourglass coil spring is in the first spring constant range is set to approximately 0.0, and when the hourglass coil spring is in the second spring constant region. The drum coil spring is set such that the decimal value of the total number of free turns is set to approximately 0.5 and the second intermediate direction is set to the target lateral force direction set by the number of turns from the terminal of the lower end turn. The suspension coil spring according to claim 1, wherein the suspension coil spring is set in a direction of +0.25 turns toward the upper side of the drum-shaped coil spring when viewed from above in the axial direction.

The first intermediate direction is directed upward from the axial direction of the drum-shaped coil spring toward the upper side of the drum-shaped coil spring with respect to a target lateral force direction set by the number of turns from the terminal of the lower end turn. +0.25 turns, the first intermediate direction and the second intermediate direction are set in opposite directions, and the drum-shaped coil spring is in the first spring constant range. The decimal value of the total free winding number is set to approximately 0.5, and the decimal value of the total free winding number when the hourglass coil spring is in the second spring constant range is set to approximately 0.0. The suspension coil spring according to claim 1, wherein