JP4605845B2

JP4605845B2 - Suspension coil spring for automobile

Info

Publication number: JP4605845B2
Application number: JP2000024526A
Authority: JP
Inventors: 敏幸今泉; 交司後藤; 伸介大倉
Original assignee: Chuo Hatsujo KK
Current assignee: Chuo Hatsujo KK
Priority date: 2000-02-01
Filing date: 2000-02-01
Publication date: 2011-01-05
Anticipated expiration: 2020-02-01
Also published as: JP2001214949A

Description

【０００１】
【発明の属する技術分野】
本発明は、自動車用懸架コイルばねに関し、特にストラット型懸架装置に好適な自動車用懸架コイルばねに係る。
【０００２】
【従来の技術】
従来より、自動車の車体懸架に圧縮コイルばねが供されており、一般的に圧縮コイルばねはそのコイル軸とばね反力の方向が一致するように設計されている。自動車用懸架装置に関しては、種々の形式のものが知られているが、車輪の位置決め用の支柱（ストラット）としてショックアブソーバ（緩衝器）を利用したストラット型懸架装置が普及している。このストラット型懸架装置においては、荷重入力軸とストラット軸との間のずれが不可避であるため、ストラットに曲げモーメントが発生し、ストラットのガイド部及びピストン部に作用する横力によってショックアブソーバとしての円滑な摺動作動が阻害される。これを防止するため、例えば円筒状の圧縮コイルばねのコイル軸をストラット軸に対してオフセットさせて曲げモーメントを相殺する技術が利用されている。
【０００３】
上記の圧縮コイルばねのコイル軸とストラット軸の関係は幾何学的に決められるため、圧縮コイルばね単体としてはオフセットが生じないように、即ちコイル軸とばね反力の方向が一致するように設計することが要求されていた。例えば、ストラット型懸架装置に供される圧縮コイルばねに関しては、本願発明者を含む研究者によって発表された「サスペンション設計における懸架コイルばねの横力低減技術」と題する論文（ばね技術研究会、１９９５年８月２８日発行）に記載のように、圧縮コイルばねの横力を最小化することが課題とされていた。
【０００４】
【発明が解決しようとする課題】
然し乍ら、自動車用懸架装置の一層の小型化が要請される今日においては、通常の円筒状圧縮コイルばねを用いストラット及びその支持機構の改良を加えるだけでは、路面荷重によってストラットに発生する曲げモーメントを打ち消すことは困難である。寧ろ、圧縮コイルばねの横力を積極的に増大させ、この圧縮コイルばねをストラット型懸架装置に適用することが必要となることが判明し、本願出願人は、ストラット型懸架装置への装着時にストラットに対し所望の横力を適切に付与し得る自動車用懸架コイルばねを提案している。
【０００５】
例えば、特願平１１−１４０６４９号及び特願平１１−１６３６５２号の出願で提案したように、自由状態においてコイル軸が湾曲するように形成し、あるいは座巻中心軸（下側座巻及び上側座巻の座巻中心を通る軸）がコイル軸に対しオフセットするように形成して、ばね反力の着力点が上側座面の略中心に位置するように調整しつつ、所望の横力を付与することとしているが、その前提となる汎用の圧縮コイルばねで構成される自動車用懸架コイルばねに関し、横力が最適となる巻数及び巻端位置に設定しておくことが肝要となる。
【０００６】
そこで、本発明は、自動車の懸架装置に装着したときに最適な横力を付与し得る自動車用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、車輪を支持するストラットの上端を車体に支持すると共に、該車体に上側座を支持し前記ストラットに下側座を固定するストラット型懸架装置に装着し、前記上側座と前記下側座との間に圧縮可能に配置する圧縮コイルばねであって、自由状態において所定の曲率で湾曲するコイル軸を有し、該コイル軸の湾曲方向が装着対象の自動車の車体外側方向となるように保持される圧縮コイルばねから成る自動車用懸架コイルばねにおいて、前記圧縮コイルばねの総巻数から前記圧縮コイルばねの上側座巻及び下側座巻の巻数を差し引いた自由巻数の小数部分を０．３乃至０．６５の値に設定すると共に、前記圧縮コイルばねの下側自由巻端位置を、前記圧縮コイルばねを装着する自動車の車体外側方向を基準に、前記上側座からの平面視で反時計方向を正として、−０．１５巻乃至＋０．０６巻の位置に設定することとしたものである。
【０００８】
また、本発明は、請求項２に記載のように、車輪を支持するストラットの上端を車体に支持すると共に、該車体に上側座を支持し前記ストラットに下側座を固定するストラット型懸架装置に装着し、前記上側座と前記下側座との間に圧縮可能に配置する圧縮コイルばねであって、自由状態において所定の曲率で湾曲するコイル軸を有し、該コイル軸の湾曲方向が装着対象の自動車の車体外側方向となるように保持される圧縮コイルばねから成る自動車用懸架コイルばねにおいて、前記圧縮コイルばねの総巻数から前記圧縮コイルばねの上側座巻及び下側座巻の巻数を差し引いた自由巻数の小数部分を０．３０乃至０．６５の値に設定すると共に、前記圧縮コイルばねの下側座巻の巻端位置が、前記圧縮コイルばねを装着する自動車の車体外側方向を基準に、前記上側座からの平面視で反時計方向を正として−９０゜近傍である場合には、前記圧縮コイルばねの上側座巻の巻数を０．５巻以下の値に設定することとしてもよい。
【００１０】
【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。先ず、図１を参照してストラット型懸架装置（以下、単に懸架装置という）の全体構成を説明すると、車体１にストラット２の上端が弾性的に支持されると共に、上側座３が車体１に支持され、ストラット２の胴部に下側座４が固定されている。これら上側座３と下側座４との間に、ストラット２を囲繞するように圧縮コイルばね５が配置されている。ストラット２の下端はナックル６に固定され、ナックル６はロアアーム７を介して車体１にピボット結合されている。而して、ナックル６に軸支される車輪８はストラット２及び圧縮コイルばね５を介して車体１に支持されると共に、ロアアーム７を介して車体１に支持されている。
【００１１】
ストラット２はシリンダ２ａと、このシリンダ２ａ内に摺動自在に支持されたロッド２ｂを備え、これらによってショックアブソーバが構成されている。ロッド２ｂの上端はストラットマウント１０を介して車体１に取り付けられ、シリンダ２ａの下端がナックル６に取り付けられる。
【００１２】
上記の構成になる懸架装置においては、図１に示すように、荷重入力軸ＡＡとばね反力軸ＲＡは一致せず、ストラット２のストラット軸ＳＡと荷重入力軸ＡＡとは角度θ１をなすのに対し、ストラット軸ＳＡとばね反力軸ＲＡとは角度θ２をなしている。尚、ＬＡはロアアーム７の軸、ＫＡはキングピン軸を表す。上記荷重入力軸ＡＡとストラット軸ＳＡの不一致に起因し、ストラット２のシリンダ２ａとロッド２ｂとの間に摺動抵抗が生じ得るが、この摺動抵抗は圧縮コイルばね５の付勢力によって発生が抑えられ、ロッド２ｂの円滑な摺動作動が確保される。
【００１３】
即ち、本実施形態の圧縮コイルばね５は、その上側座面の中心を通るコイル軸が、自由状態において所定の曲率で湾曲するように形成されており、所定の初期胴曲がりを有する。そして、圧縮コイルばね５の自由状態において湾曲内側（図１の左側）の軸方向長さが短くなる方向に、圧縮コイルばね５の下側座巻５ａの座面、即ち下側座面が、装着対象の下側座４（図１に２点鎖線で示す）に対して所定角度傾斜するように、下側座巻５ａのピッチが設定されている。尚、下側座面と下側座４との関係は相対的であり、図１では下側座４が水平で、これに対し下側座面が所定角度傾斜する関係にあるが、逆に下側座面を水平とし、これに対し下側座４が所定角度傾斜する関係としてもよい。
【００１４】
上記のように湾曲形成された圧縮コイルばね５が、略平行の上側座３と下側座４との間に介装され、そのコイル軸の湾曲方向が車体外側方向となるように保持される。このようにして、圧縮コイルばね５は、ばね反力軸が上側座３の略中心を通るように適切に支持されるので、ストラット２に対して所望の横力を適切に付与し、円滑な緩衝作動を確保することができる。
【００１５】
図２は、汎用の圧縮コイルばねの一態様を示すもので、前述の圧縮コイルばね５のように、下側座巻及び上側座巻が何れもピッグテール巻（上下面はフラット）であるが、座巻中心軸はコイル軸と一致するように形成され、装着対象の上側座及び下側座（図示せず）は何れもフラット形状に形成されている。尚。図２では胴部の一部を省略して２点鎖線で示しているので、全長が実際より短く表れている。
【００１６】
上記の態様を圧縮コイルばね５Ａとして、その上側座巻及び下側座巻の巻数に対し、下記の表１に示すように６種類の組合せで、６個のサンプルＳ１乃至Ｓ６を設定し、これらの各々に関して、コイル総巻数が＋０．５巻〜−０．５巻の範囲で０．１巻毎に、横力の変化を有限要素法によって解析した。尚、何れのサンプルのばね特性も、ばね定数が２８．４（Ｎ／mm）、取付荷重が２６００（Ｎ）、目標最大主応力が１０００（ＭＰａ）に設定されている（総巻数を変えることによって変わる取付荷重及びばね定数は、ばね自由長と線径を変えることにより特性を上記仕様に合わせた）。
【表１】

【００１７】
同様に、図３乃至図６に示すように、座巻中心軸がコイル軸と一致する圧縮コイルばね５Ｂ〜５Ｅを設定し、上記表１に示すように、夫々６個のサンプルに関して、コイル総巻数が＋０．５巻〜−０．５巻の範囲で０．１巻毎に、横力の変化を有限要素法によって解析した。以下、圧縮コイルばね５Ｂ〜５Ｅの各構成を図面を参照して説明する。先ず、図３の圧縮コイルばね５Ｂは、上側座巻はピッグテール巻であるが下側座巻はピッグオープン巻で、装着対象の上側座はフラット形状で、下側座はリード付の形状に形成されている。表１に示すように、圧縮コイルばね５Ｂ〜５Ｅについては夫々サンプルＳ１，Ｓ２，Ｓ４，Ｓ５，Ｓ７，Ｓ８の６個のサンプルを用いた。
【００１８】
次に、図４の圧縮コイルばね５Ｃは、上側座巻はピッグテール巻（上面はフラット）であるが下側座巻はオープン巻とされ、装着対象の上側座はフラット形状で、下側座はリード付の形状に形成されている。また、図５の圧縮コイルばね５Ｄも、上側座巻がピッグテール巻で下側座巻がオープン巻とされ、装着対象の上側座はフラット形状で、下側座はリード付の形状に形成されているが、上側座巻の０〜１巻間で線間接触が生ずるように設定されている。そして、図６の圧縮コイルばね５Ｅは、上側座巻がオープン巻（上面はフラットで、０〜１巻が等径）で、下側座巻がオープン巻とされ、装着対象の上側座はフラット形状で、下側座はリード付の形状に形成されているが、上側座巻の０〜１巻間で線間接触が生ずるように設定されている。
【００１９】
図７は解析結果の自由巻数と横力の関係の一例を示すもので、横軸は〔総巻数−座巻の巻数〕の自由巻数を示し、縦軸は横力の大きさを示す。尚、横力はコイル軸に垂直なばね反力成分であり、線間接触のある圧縮コイルばね５Ｄ，５Ｅに関しては、接触する上側座巻１巻と下側座巻を総巻数から差し引いた値を自由巻数とする。図７から明らかなように、横力は自由巻数によって変化し、巻数の小数部分の値が０．４５のときに横力が最大値となる。そして、圧縮コイルばね５Ａ乃至５Ｅの全てについて、横力が最大値となる自由巻数の小数部分を取り出すと、図８に示すようになり、平行な実線で囲まれた範囲内に収束している。即ち、自由巻数の小数部分の値が、０．３０〜０．６５のときに横力が最大値となる。
【００２０】
図９は、ばね反力の横方向成分の向き、即ち横力の方向を装着対象の自動車の車体外側方向と一致させるのに最適な条件を設定するための、下側自由巻端位置の基準を示すもので、圧縮コイルばねを軸方向の上方から見た平面視で、白抜矢印の方向（図９の右方）が車体外側方向を示す。この車体外側方向を基準として、図９の反時計方向を正とする巻数の値（Ｎｆ）を、下側自由巻端位置（５ｅ）を表す値として用いる。尚、図９において、下側座巻（５ａ）の巻端位置（５ｄ）から下側自由巻端位置（５ｅ）までの範囲（ＮＬ）が下側座巻（５ａ）を構成する巻数を表す。
【００２１】
而して、横軸にサンプル番号を示し、縦軸に下側自由巻端位置の巻数Ｎｆの値を示す図１０に明らかなように、圧縮コイルばね５Ａ乃至５Ｅの何れにおいても、下側自由巻端位置は、装着対象自動車の車体外側方向を基準（Ｎｆ＝０）に、上側座からの平面視で反時計方向を正とすると、平行な実線で囲まれた範囲内の−０．１５巻乃至＋０．０６巻の位置となる。
【００２２】
ところで、装着対象との関係で、下側座巻の巻端位置が固定されている場合がある。このような場合に横力の方向を車体外側方向と一致させるには、上側座巻の巻数を調整する必要がある。そこで、実際に生じ得る下側座巻の巻端位置が、車体外側方向を基準に上側座からの平面視で反時計方向を正として、＋９０°の位置と−９０°の位置のときに、横力の方向が車体外側方向と一致する上側座巻の巻数を解析した。尚、この場合には、下側座の巻端位置が固定されるので、下側座巻はリード付の下側座に適合するオープン形状とし、０．７５巻に設定する。
【００２３】
図１１は、下側座巻の巻端位置が、車体外側方向を基準に上側座からの平面視で反時計方向を正として、−９０°の位置にあって、上側座巻の巻数が０．４巻のときの、総巻数の値に応じた横力の方向を示すもので、縦軸は車体外側方向を基準とする横力方向を表す。同図から明らかなように、横力方向が０°、即ち横力の方向が車体外側方向と一致するのは、総巻数が５．６５巻の場合である。
【００２４】
一方、図１２は、下側座巻の巻端位置が、車体外側方向を基準に上側座からの平面視で反時計方向を正として、−９０°の位置にあって、上側座巻の巻数が０．７５巻のときの、総巻数の値に応じた横力の方向を示すものである。この場合には、総巻数を変化させても横力の方向を車体外側方向と一致させることは出来ない。つまり、下側座巻の巻端位置が固定されている場合には、上側座巻の巻数を適切な値に設定しないと横力の方向を車体外側方向と一致させることは出来ない。
【００２５】
そこで、下側座巻の巻端位置が、車体外側方向を基準に上側座からの平面視で反時計方向を正として、＋９０°の位置と−９０°の位置のときに、上側座巻の巻数を０．２、０．４、０．６及び０．８巻とした場合に、横力方向を車体外側方向と一致させることができるか否かについて解析したところ、−９０°の位置のときには、上側座巻の巻数が０．５巻以下の値でなければ横力の方向を車体外側方向と一致させることは出来ないことが明らかとなった。これに対し、下側座巻の巻端位置が、車体外側方向を基準に上側座からの平面視で反時計方向を正として、＋９０°の位置のときには、上側座巻の巻数が０．２〜０．８巻の何れの場合にも、横力の方向を車体外側方向と一致させることが可能な総巻数が存在することが明らかとなった。
【００２６】
【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に係る自動車用懸架コイルばねは、コイル軸の湾曲方向が装着対象の自動車の車体外側方向となるように保持される圧縮コイルばねから成り、この圧縮コイルばねの総巻数から上側座巻及び下側座巻の巻数を差し引いた自由巻数の小数部分を０．３０乃至０．６５の値に設定することとしているので、ストラット型懸架装置に装着したときに最大の横力を付与し得る巻数とすると共に、圧縮コイルばねの下側自由巻端位置を、自動車の車体外側方向を基準に、上側座からの平面視で反時計方向を正として、−０．１５巻乃至＋０．０６巻の位置に設定することとしているので、横力の方向を車体外側方向即ちコイル軸の湾曲方向と一致させ得る自動車用懸架コイルばねを構成することができる。従って、この自動車用懸架コイルばねに基づき、同懸架装置に装着したときに所望の横力を適切に付与し得る自動車用懸架コイルばねを、容易に形成し、安定して提供することができる。
【００２８】
また、請求項２に係る自動車用懸架コイルばねは、コイル軸の湾曲方向が装着対象の自動車の車体外側方向となるように保持される圧縮コイルばねから成り、この圧縮コイルばねの総巻数から上側座巻及び下側座巻の巻数を差し引いた自由巻数の小数部分を０．３０乃至０．６５の値に設定することとしているので、ストラット型懸架装置に装着したときに最大の横力を付与し得る巻数とすると共に、圧縮コイルばねの下側座巻の巻端位置が、自動車の車体外側方向を基準に、前記上側座からの平面視で反時計方向を正として−９０゜近傍である場合には、上側座巻の巻数を０．５巻以下の値に設定することとしているので、ストラット型懸架装置に装着したときに下側座巻の巻端位置が−９０゜近傍に固定される場合にも、横力方向を車体外側方向即ちコイル軸の湾曲方向と一致させ得る自動車用懸架コイルばねを構成することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る圧縮コイルばねを自動車用懸架装置に装着した状態を示す断面図である。
【図２】本発明の一実施形態に供する汎用の圧縮コイルばねの第１の態様を示す正面図である。
【図３】本発明の一実施形態に供する汎用の圧縮コイルばねの第２の態様を示す正面図である。
【図４】本発明の一実施形態に供する汎用の圧縮コイルばねの第３の態様を示す正面図である。
【図５】本発明の一実施形態に供する汎用の圧縮コイルばねの第４の態様を示す正面図である。
【図６】本発明の一実施形態に供する汎用の圧縮コイルばねの第５の態様を示す正面図である。
【図７】本発明の一実施形態に供する汎用の圧縮コイルばねの一例における自由巻数と横力の関係の一例を示すグラフである。
【図８】図２乃至図６に示す圧縮コイルばねの全てについて、横力が最大値となる自由巻数の小数部分を示すグラフである。
【図９】本発明の一実施形態における、横力の方向を車体外側方向と一致させるのに最適な条件を設定するための、下側自由巻端位置の基準を示す平面図である。
【図１０】図２乃至図６に示す圧縮コイルばねの全てについて、横力の方向を車体外側方向と一致させる下側自由巻端位置を、車体外側方向からの巻数で示すグラフである。
【図１１】下側座巻の巻端位置が、車体外側方向を基準に上側座からの平面視で反時計方向を正として、−９０°の位置にあって、上側座巻の巻数が０．４巻のときの、総巻数の値に応じた横力の方向を示すグラフである。
【図１２】下側座巻の巻端位置が、車体外側方向を基準に上側座からの平面視で反時計方向を正として、−９０°の位置にあって、上側座巻の巻数が０．７５巻のときの、総巻数の値に応じた横力の方向を示すグラフである。
【符号の説明】
１車体，２ストラット，３上側座，４下側座，
５圧縮コイルばね，５ａ下側座巻，５ｂ上側座巻，
６ナックル，７ロアアーム，８車輪，
１０ストラットマウント[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automobile suspension coil spring, and more particularly to an automobile suspension coil spring suitable for a strut type suspension device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a compression coil spring has been provided for a vehicle body suspension of an automobile. Generally, a compression coil spring is designed so that the direction of a spring reaction force coincides with the coil shaft. Various types of suspensions for automobiles are known, but a strut type suspension device using a shock absorber (buffer) as a wheel positioning strut (strut) is widely used. In this strut-type suspension system, since the displacement between the load input shaft and the strut shaft is inevitable, a bending moment is generated in the strut, and a lateral force acting on the guide portion and the piston portion of the strut serves as a shock absorber. Smooth sliding operation is hindered. In order to prevent this, for example, a technique of offsetting the bending moment by offsetting the coil axis of a cylindrical compression coil spring with respect to the strut axis is used.
[0003]
Since the relationship between the coil axis and the strut axis of the above compression coil spring is determined geometrically, the compression coil spring itself is designed so that no offset occurs, that is, the direction of the coil axis and the spring reaction force coincide. It was requested to do. For example, regarding a compression coil spring provided for a strut-type suspension device, a paper entitled “Suspension coil spring lateral force reduction technology in suspension design” published by researchers including the present inventor (Spring Technology Study Group, 1995). As described in (issued on August 28, 1980), minimizing the lateral force of the compression coil spring has been an issue.
[0004]
[Problems to be solved by the invention]
However, in the present day when further downsizing of the suspension system for automobiles is required, the bending moment generated in the strut due to the road load can be reduced only by improving the strut and its supporting mechanism using a normal cylindrical compression coil spring. It is difficult to counteract. Rather, it has been found that it is necessary to actively increase the lateral force of the compression coil spring and to apply this compression coil spring to the strut type suspension device. A suspension coil spring for an automobile that can appropriately apply a desired lateral force to a strut has been proposed.
[0005]
For example, as proposed in the applications of Japanese Patent Application Nos. 11-140649 and 11-163652, the coil axis is formed to be curved in a free state, or the center axis of the end winding (the lower end winding and the upper end winding). The axis that passes through the center of the end winding is offset with respect to the coil axis, and the desired lateral force is adjusted while adjusting the spring reaction force's point of application at the approximate center of the upper seat surface. It is important to set the number of turns and the position of the winding end at which the lateral force is optimal for the suspension coil spring for automobiles composed of a general-purpose compression coil spring which is the premise.
[0006]
Then, this invention makes it a subject to provide the suspension coil spring for motor vehicles which can provide optimal lateral force when it mounts | wears with the suspension device of a motor vehicle.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a vehicle body in which an upper end of a strut that supports a wheel is supported on a vehicle body, an upper seat is supported on the vehicle body, and a lower seat is mounted on the strut. A compression coil spring that is mounted on a strut-type suspension device to be fixed and is disposed so as to be compressible between the upper seat and the lower seat, and has a coil shaft that is curved with a predetermined curvature in a free state, In a suspension coil spring for a vehicle comprising a compression coil spring that is held so that the bending direction of the coil shaft is the vehicle body outer direction of the vehicle to be mounted , the upper end winding of the compression coil spring and the total number of turns of the compression coil spring The decimal part of the free winding number obtained by subtracting the number of turns of the lower winding is set to a value of 0.3 to 0.65, and the lower free winding end position of the compression coil spring is mounted on the compression coil spring. Relative to the vehicle body outer side of the dynamic wheel, a counter-clockwise direction in a plan view from the upper seat as positive, in which it was decided to set the position of -0.15 Volume to +0.06 vol.
[0008]
Further, according to the present invention, the strut-type suspension device according to claim 2, wherein the upper end of the strut that supports the wheel is supported by the vehicle body, the upper seat is supported by the vehicle body, and the lower seat is fixed to the strut. A compression coil spring that is disposed so as to be compressible between the upper seat and the lower seat, and has a coil shaft that bends at a predetermined curvature in a free state, and the bending direction of the coil shaft is In a suspension coil spring for an automobile composed of a compression coil spring that is held so as to be in the vehicle body outer side direction of the mounting target vehicle, the number of turns of the upper and lower end windings of the compression coil spring is determined from the total number of turns of the compression coil spring. Is set to a value of 0.30 to 0.65, and the winding end position of the lower end winding of the compression coil spring is set to the outside of the vehicle body on which the compression coil spring is mounted. When the counterclockwise direction is positive in the plan view from the upper seat and the vicinity is -90 °, the number of turns of the upper coil of the compression coil spring is set to a value of 0.5 or less. It is good as well.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the overall structure of a strut type suspension device (hereinafter simply referred to as a suspension device) will be described with reference to FIG. 1. The upper end of the strut 2 is elastically supported by the vehicle body 1 and the upper seat 3 is attached to the vehicle body 1. The lower seat 4 is fixed to the trunk of the strut 2. A compression coil spring 5 is disposed between the upper seat 3 and the lower seat 4 so as to surround the strut 2. The lower end of the strut 2 is fixed to a knuckle 6, and the knuckle 6 is pivotally connected to the vehicle body 1 via a lower arm 7. Thus, the wheel 8 pivotally supported by the knuckle 6 is supported by the vehicle body 1 via the strut 2 and the compression coil spring 5, and is supported by the vehicle body 1 via the lower arm 7.
[0011]
The strut 2 includes a cylinder 2a and a rod 2b slidably supported in the cylinder 2a, and these constitute a shock absorber. The upper end of the rod 2b is attached to the vehicle body 1 via the strut mount 10, and the lower end of the cylinder 2a is attached to the knuckle 6.
[0012]
In the suspension device having the above-described configuration, as shown in FIG. 1, the load input shaft AA and the spring reaction force axis RA do not coincide with each other, and the strut shaft SA of the strut 2 and the load input shaft AA form an angle θ1. On the other hand, the strut axis SA and the spring reaction force axis RA form an angle θ2. Note that LA represents an axis of the lower arm 7, and KA represents a kingpin axis. Due to the mismatch between the load input shaft AA and the strut shaft SA, a sliding resistance may be generated between the cylinder 2 a and the rod 2 b of the strut 2, but this sliding resistance is generated by the biasing force of the compression coil spring 5. Thus, smooth sliding operation of the rod 2b is ensured.
[0013]
That is, the compression coil spring 5 of the present embodiment is formed such that the coil axis passing through the center of the upper seat surface is curved with a predetermined curvature in a free state, and has a predetermined initial bending. In the free state of the compression coil spring 5, the seat surface of the lower end winding 5a of the compression coil spring 5 in the direction in which the axial length of the curved inner side (left side in FIG. 1) becomes shorter, that is, the lower seat surface, The pitch of the lower end winding 5a is set so as to be inclined at a predetermined angle with respect to the lower side seat 4 (indicated by a two-dot chain line in FIG. 1) to be mounted. The relationship between the lower seat surface and the lower seat 4 is relative. In FIG. 1, the lower seat 4 is horizontal and the lower seat surface is inclined at a predetermined angle. The lower seat surface may be horizontal and the lower seat 4 may be inclined at a predetermined angle.
[0014]
The compression coil spring 5 that is curved as described above is interposed between the substantially parallel upper seat 3 and lower seat 4 and is held so that the curving direction of the coil axis is the vehicle body outer side direction. . In this way, the compression coil spring 5 is appropriately supported so that the spring reaction force axis passes through the approximate center of the upper seat 3, so that a desired lateral force is appropriately applied to the strut 2 and smooth. Buffering operation can be ensured.
[0015]
FIG. 2 shows an aspect of a general-purpose compression coil spring. Like the compression coil spring 5, the lower end winding and the upper end winding are both pigtail windings (the upper and lower surfaces are flat). The center axis of the end winding is formed so as to coincide with the coil axis, and the upper seat and the lower seat (not shown) to be mounted are both formed in a flat shape. still. In FIG. 2, a part of the body portion is omitted and shown by a two-dot chain line, so that the total length appears shorter than the actual length.
[0016]
The above-described embodiment is a compression coil spring 5A, and six samples S1 to S6 are set in six combinations as shown in Table 1 below for the number of turns of the upper end winding and the lower end winding. For each of the above, the change in the lateral force was analyzed by the finite element method every 0.1 turns in the range of the total number of coil turns of +0.5 to -0.5 turns. The spring characteristics of all samples are set such that the spring constant is 28.4 (N / mm), the mounting load is 2600 (N), and the target maximum principal stress is 1000 (MPa) (change the total number of turns. The mounting load and spring constant vary depending on the above specifications by changing the spring free length and wire diameter).
[Table 1]

[0017]
Similarly, as shown in FIGS. 3 to 6, compression coil springs 5B to 5E in which the center axis of the end winding coincides with the coil axis are set, and as shown in Table 1 above, the coil total for each of the six samples is set. Changes in lateral force were analyzed by the finite element method every 0.1 turns in the range of the number of turns from +0.5 to -0.5. Hereinafter, each structure of the compression coil springs 5B to 5E will be described with reference to the drawings. First, in the compression coil spring 5B of FIG. 3, the upper end winding is a pigtail winding, the lower end winding is a pig open winding, the upper seat to be mounted is flat, and the lower seat is formed in a shape with a lead. Has been. As shown in Table 1, six samples S1, S2, S4, S5, S7, and S8 were used for the compression coil springs 5B to 5E, respectively.
[0018]
Next, in the compression coil spring 5C of FIG. 4, the upper end winding is a pigtail winding (the upper surface is flat), but the lower end winding is an open winding, the upper seat to be mounted is flat, and the lower seat is It is formed in a shape with leads. Also, the compression coil spring 5D of FIG. 5 is formed such that the upper end winding is a pigtail winding and the lower end winding is an open winding, the upper seat to be mounted is flat, and the lower seat is formed with a lead. However, it is set so that line-to-line contact occurs between 0 to 1 of the upper end winding. In the compression coil spring 5E of FIG. 6, the upper end winding is an open winding (the upper surface is flat, 0 to 1 is the same diameter), the lower end winding is an open winding, and the upper seat to be mounted is flat. In shape, the lower seat is formed in a shape with a lead, but is set so that line-to-line contact occurs between 0 to 1 of the upper end winding.
[0019]
FIG. 7 shows an example of the relationship between the number of free turns and the lateral force of the analysis result. The horizontal axis represents the number of free turns of [total number of turns−the number of turns of the counter winding], and the vertical axis represents the magnitude of the lateral force. The lateral force is a spring reaction force component perpendicular to the coil axis. For

compression coil springs

5D and 5E having line-to-line contact, the value obtained by subtracting the upper and lower end turns from the total number of turns. Is the number of free turns. As is clear from FIG. 7, the lateral force changes depending on the number of free turns, and the side force becomes the maximum value when the value of the decimal part of the number of turns is 0.45. For all of the compression coil springs 5A to 5E, when the fractional part of the free winding number at which the lateral force becomes the maximum value is taken out, it becomes as shown in FIG. 8 and converges within a range surrounded by parallel solid lines. . That is, when the value of the decimal part of the free winding number is 0.30 to 0.65, the lateral force becomes the maximum value.
[0020]
FIG. 9 is a reference of the lower free winding end position for setting an optimum condition for making the direction of the lateral component of the spring reaction force, that is, the direction of the lateral force coincide with the vehicle body outer direction of the mounting target vehicle. In the plan view of the compression coil spring as viewed from above in the axial direction, the direction of the white arrow (the right side in FIG. 9) indicates the vehicle body outer side direction. With reference to the vehicle body outer side direction, the value (Nf) of the number of turns with the counterclockwise direction in FIG. 9 being positive is used as a value representing the lower free winding end position (5e). In FIG. 9, the range (NL) from the winding end position (5d) of the lower end winding (5a) to the lower free winding end position (5e) represents the number of turns constituting the lower end winding (5a). .
[0021]
Thus, as shown in FIG. 10, in which the horizontal axis indicates the sample number and the vertical axis indicates the value of the number of turns Nf at the lower free winding end position, any of the compression coil springs 5A to 5E has a lower free position. The winding end position is -0.15 within a range surrounded by parallel solid lines when the vehicle body outside direction of the mounting target vehicle is a reference (Nf = 0) and the counterclockwise direction is positive in plan view from the upper seat. The position is from winding to +0.06 winding.
[0022]
By the way, there is a case where the winding end position of the lower end winding is fixed in relation to the mounting target. In such a case, in order to make the direction of the lateral force coincide with the vehicle body outer direction, it is necessary to adjust the number of turns of the upper end winding. Therefore, when the winding end position of the lower end winding that can actually occur is a position of + 90 ° and a position of −90 ° with the counterclockwise direction being positive in a plan view from the upper seat with respect to the vehicle body outer side direction, The number of turns of the upper end winding where the direction of the lateral force coincides with the vehicle body outer direction was analyzed. In this case, since the winding end position of the lower seat is fixed, the lower seat winding has an open shape suitable for the lower seat with leads and is set to 0.75.
[0023]
FIG. 11 shows that the winding position of the lower end winding is at a position of −90 ° with the counterclockwise direction being positive in a plan view from the upper side with respect to the vehicle body outer side direction, and the number of windings of the upper end winding is 0. .4 indicates the direction of the lateral force according to the value of the total number of turns, and the vertical axis indicates the direction of the lateral force with reference to the vehicle body outer side direction. As is apparent from the figure, the lateral force direction is 0 °, that is, the direction of the lateral force coincides with the vehicle body outer direction when the total number of turns is 5.65.
[0024]
On the other hand, FIG. 12 shows that the winding position of the lower end winding is at a position of −90 ° with the counterclockwise direction being positive in plan view from the upper side with respect to the vehicle body outer direction, and the number of windings of the upper end winding. Indicates the direction of the lateral force according to the value of the total number of turns when is 0.75. In this case, even if the total number of turns is changed, the direction of the lateral force cannot be made coincident with the vehicle body outer side direction. That is, when the winding end position of the lower end winding is fixed, the direction of the lateral force cannot be matched with the vehicle body outside direction unless the upper end winding is set to an appropriate value.
[0025]
Therefore, when the winding end position of the lower end winding is at a position of + 90 ° and a position of −90 ° with the counterclockwise direction being positive in a plan view from the upper seat with respect to the vehicle body outer side direction, When the number of turns was 0.2, 0.4, 0.6, and 0.8, it was analyzed whether or not the lateral force direction could coincide with the vehicle body outer direction. In some cases, it has become clear that the direction of the lateral force cannot coincide with the vehicle body outside direction unless the number of turns of the upper end winding is 0.5 or less. On the other hand, when the winding end position of the lower end winding is at a position of + 90 ° with the counterclockwise direction being positive in plan view from the upper side with respect to the vehicle body outer side direction, the number of turns of the upper end winding is 0.2. In any case of ~ 0.8 turns, it has become clear that there is a total number of turns that can make the direction of the lateral force coincide with the vehicle body outer side direction.
[0026]
【The invention's effect】
Since this invention is comprised as mentioned above, there exist the following effects. That is, the suspension coil spring for an automobile according to claim 1 is composed of a compression coil spring that is held so that the bending direction of the coil shaft is in the vehicle body outer side direction of the automobile to be mounted, and is above the total number of turns of the compression coil spring. Since the fractional part of the number of free turns after subtracting the number of turns of the end turn and the lower end turn is set to a value of 0.30 to 0.65, the maximum lateral force is applied when mounted on a strut type suspension system. In addition, the lower free winding end position of the compression coil spring is set to −0.15 to +0. Since the position is set to 06, it is possible to configure a suspension coil spring for an automobile that can make the direction of lateral force coincide with the vehicle body outer side direction, that is, the bending direction of the coil shaft . Therefore, based on this suspension coil spring for automobiles, it is possible to easily form and stably provide a suspension coil spring for automobiles that can appropriately apply a desired lateral force when mounted on the suspension device.
[0028]
The suspension coil spring for an automobile according to claim 2 is composed of a compression coil spring that is held so that the bending direction of the coil shaft is in the vehicle body outer side direction of the automobile to be mounted, and is above the total number of turns of the compression coil spring. Since the fractional part of the number of free turns after subtracting the number of turns of the end turn and the lower end turn is set to a value of 0.30 to 0.65, the maximum lateral force is applied when mounted on a strut type suspension system. The winding end position of the lower end winding of the compression coil spring is in the vicinity of −90 ° with the counterclockwise direction being positive in plan view from the upper seat with respect to the vehicle body outer side direction of the automobile. In this case, the number of turns of the upper end winding is set to a value of 0.5 or less, so that the winding end position of the lower end winding is fixed in the vicinity of −90 ° when mounted on the strut type suspension device. Even when the vehicle It is possible to configure the automotive suspension coil spring which can be matched with the bending direction of the side direction, i.e. the coil axis.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a state where a compression coil spring according to an embodiment of the present invention is mounted on a suspension system for an automobile.
FIG. 2 is a front view showing a first aspect of a general-purpose compression coil spring provided for an embodiment of the present invention.
FIG. 3 is a front view showing a second aspect of a general-purpose compression coil spring provided for an embodiment of the present invention.
FIG. 4 is a front view showing a third aspect of a general-purpose compression coil spring provided for one embodiment of the present invention.
FIG. 5 is a front view showing a fourth aspect of a general-purpose compression coil spring provided for an embodiment of the present invention.
FIG. 6 is a front view showing a fifth aspect of a general-purpose compression coil spring provided for an embodiment of the present invention.
FIG. 7 is a graph showing an example of the relationship between the number of free turns and lateral force in an example of a general-purpose compression coil spring provided for an embodiment of the present invention.
FIG. 8 is a graph showing a fractional portion of the free winding number at which the lateral force is maximum for all the compression coil springs shown in FIGS. 2 to 6;
FIG. 9 is a plan view showing a reference for a lower free winding end position for setting an optimum condition for making the direction of the lateral force coincide with the vehicle body outer direction in one embodiment of the present invention.
FIG. 10 is a graph showing the lower free winding end position at which the direction of the lateral force coincides with the vehicle body outer direction, in terms of the number of turns from the vehicle body outer direction, for all of the compression coil springs shown in FIGS.
FIG. 11 shows that the winding position of the lower end winding is at a position of −90 ° with the counterclockwise direction being positive in a plan view from the upper side with respect to the vehicle body outer side direction, and the number of windings of the upper end winding is 0. It is a graph which shows the direction of lateral force according to the value of the total number of turns at the time of .4 winding.
FIG. 12 shows that the winding end position of the lower end winding is at a position of −90 ° with the counterclockwise direction being positive in plan view from the upper side with respect to the vehicle body outer side direction, and the number of windings of the upper end winding is 0. It is a graph which shows the direction of the lateral force according to the value of the total number of turns at the time of .75 turns.
[Explanation of symbols]
1 body, 2 struts, 3 upper seats, 4 lower seats,
5 compression coil spring, 5a lower end winding, 5b upper end winding,
6 knuckles, 7 lower arms, 8 wheels,
10 Strut mount

Claims

The upper end of the strut that supports the wheel is supported by the vehicle body, and is mounted on a strut-type suspension device that supports the upper seat on the vehicle body and fixes the lower seat to the strut, and between the upper seat and the lower seat. A compression coil spring that is arranged so as to be compressible , and has a coil shaft that bends at a predetermined curvature in a free state, and is held so that the bending direction of the coil shaft is the outer direction of the vehicle body to be mounted. In the suspension coil spring for automobiles composed of compression coil springs, the fractional part of the free turns obtained by subtracting the number of turns of the upper and lower end turns of the compression coil spring from the total number of turns of the compression coil spring is 0.30 to 0.00. The value of 65 is set, and the lower free winding end position of the compression coil spring is counterclockwise in a plan view from the upper seat with respect to the vehicle body outer side direction where the compression coil spring is mounted. The direction positive, automotive suspension coil spring, characterized in that setting the position of -0.15 Volume to +0.06 vol.

The upper end of the strut that supports the wheel is supported by the vehicle body, and is mounted on a strut-type suspension device that supports the upper seat on the vehicle body and fixes the lower seat to the strut, and between the upper seat and the lower seat. A compression coil spring that is arranged so as to be compressible , and has a coil shaft that bends at a predetermined curvature in a free state, and is held so that the bending direction of the coil shaft is the outer direction of the vehicle body to be mounted. In the suspension coil spring for automobiles composed of compression coil springs, the fractional part of the free turns obtained by subtracting the number of turns of the upper and lower end turns of the compression coil spring from the total number of turns of the compression coil spring is 0.30 to 0.00. In addition, the winding end position of the lower end winding of the compression coil spring is opposite to the vehicle body outer side direction of the automobile on which the compression coil spring is mounted in a plan view from the upper seat. If it is -90 ° near the total direction positive automotive suspension coil spring, characterized in that setting the number of turns of the upper seating winding of the compression coil spring to a value of 0.5 vol below.