JP3864241B2

JP3864241B2 - Air bag for occupant protection device

Info

Publication number: JP3864241B2
Application number: JP18715897A
Authority: JP
Inventors: 正晴垣谷; 晃文塙
Original assignee: オートリブ・ジャパン株式会社
Priority date: 1997-06-30
Filing date: 1997-06-30
Publication date: 2006-12-27
Anticipated expiration: 2017-06-30
Also published as: JPH1120588A

Description

【０００１】
【発明の属する技術分野】
本発明は、自動車の衝突時の衝撃から乗員を確保するためのエアバッグ装置において使用するエアバッグに関するもので、特に、衝突の軽重によってエアバッグの展開形態を変化させる事の可能なエアバッグの構造に関するものである。
【０００２】
従来のエアバッグの典型的な構造は、図１２に示している様に、乗員側に位置する表側基布１とガス発生器３を装着するガス発生器取付用開口２ａを有する裏側基布２とを重ね合わせ、両基布１，２の周縁部を縫製部４により縫着して袋状に成形したものである。該エアバッグＡの裏側基布２のガス発生器取付用開口２ａ内には、ガス発生器３が挿入され、該ガス発生器３のフランジ３ａと裏側基布２の開口部周縁２ｂとを、ボルト等の固定手段９によって固定している。エアバッグＡの展開時には、ガス発生器３のガス放出口３ｂから急速に放出される高圧のガスによって、エアバッグＡは、乗員と車体との間で極めて短時間の内に膨張し、乗員と車体との衝突を緩和するものである。
【０００３】
ところで、エアバッグＡの展開は、車体の適所に設置された衝突センサにより衝突が検知されると、その衝突の軽重に拘らず、一定の条件で急速に展開する様に設計されている。このために、比較的軽度の衝突においては、急速に展開するエアバッグの膨張力によって乗員が跳ね飛ばされて傷害を受けたり、或いは、極めて重大な衝突においては、エアバッグの展開速度が遅すぎて乗員の保護が不完全となる場合が生じる。又、乗員の姿勢や位置に拘らず、常に一定の条件でエアバッグが展開する様になっているので、乗員がエアバッグに近い位置に着座している場合には、エアバッグの展開によって跳ね飛ばされたりする事態も生じている。
【０００４】
そこで、最近では、衝突の軽重或いは乗員の姿勢や位置を検知して、エアバッグの展開形態を制御する方式、所謂スマートエアバッグ方式が提案されている。具体的には、２つのガス発生器を用いて１つのエアバッグを展開させる方式であり、衝突の軽重や乗員の姿勢等に応じて、該２つのガス発生器の点火タイミングを調整したり、或いはいずれか一方のみのガス発生器を作動させる事によって、エアバッグの展開形態を制御しようとするものである。
【０００５】
【発明が解決しようとする課題】
係るスマートエアバッグ方式においては、エアバッグ自体の容積が一定であるため、少量のガスでエアバッグを展開しようとしても、エアバッグの展開は不十分となって乗員に傷害を与えるおそれがあり、又、点火時間差を大きくして穏やかなエアバッグの展開を行うにも、衝突後短時間の内に展開を完了しなければならないエアバッグにあっては、自ずと限界があった。
【０００６】
そこで、本発明は、上記事情に鑑み、エアバッグの展開容量自体を変化させ得る様になす事によって、前記スマートエアバッグ方式に最適なエアバッグを提供する事を目的とするものである。
【０００７】
【課題を解決するための手段】
本発明は、上記課題を解決するためになされたものであって、ガス発生器３から供給されるガス量によって、展開形態を変化させるようにした乗員保護装置用エアバッグであって、乗員側に位置する表側基布１と、ガス発生器取付開口２ａを有する裏側基布２との周縁部を互いに縫着してなる第一縫製部４と、前記表側基布１と裏側基布２との間に配置された内側基布８の周縁部を前記裏側基布２に縫着してなる第三縫製部７とを有し、前記裏側基布２の前記第三縫製部７の内側に内側ガス放出孔６ａが、又、前記第三縫製部７と前記第一縫製部４との間に外側ガス放出孔６ｂが、夫々形成されており、前記ガス発生器３からのガス供給量が所定量以下の場合には、前記内側基布８の内側に形成される小空間Ｓのみを膨張させ、前記ガス供給量が所定量を越えると、前記第三縫製部７を破断して、前記表側基布１と裏側基布２とによって形成される大空間Ｌを膨張させるようにし、前記第三縫製部７の少なくとも一部７ａが、前記所定のガス供給量を越えると破断するように、該縫製部７に縫着力の弱い破断部７ａを形成してなり、前記第三縫製部７の前記破断部７ａが、前記裏側基布２のガス発生器取付開口２ａに対して対称な位置に複数箇所形成されてなるものである。
【０００９】
上記の様に、エアバッグ内に小空間と大空間とが形成される様になし、前記衝突の軽重や乗員保護装置の姿勢等に応じて、いずれかの空間を膨張させ得る様になしたものである。この２つの空間のいずれを膨張させるかは、２つのガス発生器の一方または双方を点火する事によって選択できる様になっている。即ち、大小両空間の境界部が、エアバッグ内に供給されるガス量が所定量以上になると破断し、小空間から大空間にガスが供給されて、大空間が膨張する様に構成されている。
【００１０】
【発明の実施の形態】
以下に、図面によって本発明を詳細に説明する。図１は、本発明に係る第一のエアバッグを示す平面図（背面図）であり、図２は、そのＩ−Ｉ断面図である。同図において、エアバッグＡは、表側基布１と裏側基布２とを、その周縁部に沿って形成された第一縫製部４により一体的に縫着され、更に、両基布１，２の中間位置も、第二縫製部５により縫着されている。裏側基布２の略中央には、ガス発生器取付開口２ａが形成され、又、前記第一縫製部４と第二縫製部５との間、及び前記第二縫製部５の内側には、夫々外側ガス放出孔６ｂ及び内側ガス放出孔６ａが形成されている。
【００１１】
前記ガス発生器取付開口２ａには、ガス発生器３が図２に示す様に挿入され、従来と同様に、ガス発生器のフランジ３ａと裏側基布２の開口部周縁２ｂとを、ボルト等の固定手段９によって固定している。尚、２ｃは、裏側基布２に穿設されている固定手段９の挿入孔である。
【００１２】
次に、本発明で使用するガス発生器３の構造の１例を、図１１によって説明する。図１１は、通常運転席用エアバッグに用いられている短円筒型ガス発生器の横断面を示すもので、ガス発生器３は、円筒状のハウジング２１内を、仕切部材２２によって大容量の第一ガス発生器３１と小容量の第二ガス発生器３２との２つのガス発生器に分割され、容量の異なる２つのガス発生器を内包した構造となっている。各ガス発生器３１，３２内には、通常と同様にガス発生剤２３及びフィルタ２４と共に、各ガス発生器内のガス発生剤２３を着火させる点火装置２５とが配置されており、夫々独立して作動する様に構成されている。従って、一方のガス発生器が作動しても、そこで発生する高温ガスによって他方のガス発生器が類焼しない様に、仕切部材とフィルタとの間等には、適宜断熱処理がなされている事は言うまでもない。又、ハウジング２１の円周方向には、各ガス発生器に対応した位置に、適当数のガス放出口３ｂが形成されている。尚、前記大容量のガス発生器３１と小容量のガス発生器３２とのガス発生能力の比は、６：４〜８：２程度の範囲に設定されている。
【００１３】
このガス発生器３の作動について説明すると、衝突センサからの衝突の軽重等の判断により、両ガス発生器３１，３２には、次の３種類の点火形態の指示がなされる。
（ａ）大容量の第一ガス発生器３１のみを点火させる。
（ｂ）先ず大容量の第一ガス発生器３１を点火させ、微小時間の点火時間差をお
いて小容量の第二ガス発生器を点火させる。
（ｃ）２つのガス発生器３１，３２を同時に点火させる。
これらの点火形態は、衝突の軽重で言えば、（ａ）は、軽度の衝突の場合であり、（ｂ）は、中程度の衝突であり、（ｃ）は、重大な衝突の場合の展開形態と言える。
【００１４】
尚、図１１には、短円筒型のガス発生器の例を示したが、本発明のエアバッグに適用可能なガス発生器としては、長円筒型ガス発生器を、その長手方向に仕切部材によって２分割した助手席用ガス発生器もあるが、いずれにしても本発明において使用するガス発生器の形状，構造は限定されるものではない。
【００１５】
次に、上記ガス発生器によるエアバッグＡの展開形態について、図３、図４によって説明する。車両の衝突を車体の適所に配置されている衝突センサが検知し、その衝突の程度が、重大な衝突か軽度の衝突かの衝突の軽重を演算装置によって
演算し、衝突が軽度と判断されると、容量の大きな第一ガス発生器３１のみが点火され、ガス発生器のガス放出口３ｂからエアバッグ内にガスが放出され、前記第二縫製部５の内側に表側基布１と裏側基布２とによって形成された小空間Ｓが膨張し、余剰ガスは、該小空間Ｓの膨張を維持しつつ前記第二縫製部５の内側に形成されている内側ガス放出孔６ａから外部に放出される事になる。この様にして、エアバッグは、小空間Ｓのみを従来のエアバッグに比して比較的遅いガス供給速度の第一ガス発生器３１からの供給ガスのみによって穏やかに展開し、乗員は、比較的軽度の衝突に対して確実に保護される事になる。
【００１６】
ここで、第一ガス発生器３１から放出されるガス供給速度は、ガス放出孔６ａからガスが放出されつつも、前記小空間Ｓを膨張させ且つこれを所定時間維持するには必要且つ十分な量であるが、前記第二縫製部５の縫製線を破断させる様な高い内圧が発生するには不十分なガス供給量に設定されている。換言すると、前記第二縫製部は、第一ガス発生器３１から供給されるガス供給量では破断しない程度の強度で縫着されていると言える。
【００１７】
又、前記演算装置によって、衝突の程度が中程度であり、前記小空間Ｓの膨張のみでは不十分と判断された場合には、前記２つのガス発生器３１，３２の点火タイミングをずらして点火する。即ち、先ず容量の大きな第一ガス発生器３１が点火され、前述の要領でエアバッグの小空間Ｓを膨張させ、続いて所定微小時間後に、容量の小さな第二ガス発生器３２が点火される。第二ガス発生器３２が点火されると、２つのガス発生器から発生するガスが、小空間Ｓ内に同時に供給される事になるので、小空間Ｓ内に供給されるガス供給量とガス放出孔６ａから放出されるガス量のバランスが崩れて該小空間Ｓ内の内圧が上昇し、第二縫製部５の縫製線が破断して、図４に示す様に、表側基布１と裏側基布２との周縁の第一縫製部４内に形成された大空間Ｌが膨張し、余剰ガスは、内側ガス放出孔６ａと外側ガス放出孔６ｂの両方から外部に放出されつつ、該大空間Ｌの膨張を所定時間維持する事になる。この様にして、エアバッグは、先ず第一ガス発生器３１からの供給ガスのみによって内部の小空間Ｓを穏やかに展開し、続いて両ガス発生器３１，３２からの供給ガスによって急速に展開され、乗員が車体に衝突するのを柔らかく保護する事になる。
【００１８】
ここで、前記第二縫製部５の縫着強度は、前記第一ガス発生器３１のガス発生量では破断しないが、第一、第二ガス発生器３１，３２からのガスが同時に供給された場合には破断する程度の強度に設定されていると言える。
【００１９】
次に、前記演算装置によって衝突の程度が重大であると判断された場合には、前記２つのガス発生器３１，３２の点火装置を同時に作動させて、大量のガスをガス放出口３ｂからエアバッグ内に一気に供給する事になる。この場合には、ガス発生器からのガスは、先ず前記小空間Ｓ内に流入するが、第一，第二ガス発生器から同時に大量のガスが供給されるため、小空間Ｓ内の内圧は急速に上昇するし、このため第二縫製部５は瞬時に破断して大空間Ｌが急速に膨張し、急速に車体に向かって移動する乗員と車体との間にエアバッグを展開して乗員を保護する事になる。
【００２０】
次に、本発明の第二のタイプのエアバッグについて、図５〜８によって説明する。図５は、本発明の第二のタイプのエアバッグの平面図（背面図）であり、図６は、そのＩＩ−ＩＩ断面図である。この第二のタイプのエアバッグは、表側基布１と裏側基布２との間に内側基布８を配置している点で、前記第一のタイプのエアバッグと異なっている。このエアバッグでは、表側基布１と裏側基布２とは、その周縁部が第一縫製部４によって縫着され、内側基布８は、裏側基布２に形成されているガス発生器取付開口２ａを覆う様に配置され、その周縁部は、裏側基布２と第三縫製部７によって縫着されている。これにより、第三縫製部７の内側に小空間Ｓが形成され、前記第一縫製部４の内側には大空間Ｌが形成されている。又、裏側基布２の第三縫製部７の内側には、小空間Ｓに開口する内側ガス放出孔
６ａが形成され、更に第一縫製部４と第三縫製部７との間には、前記大空間Ｌに開口する外側ガス放出孔６ｂが形成されている点は前述のケースと同一である。又、前記第三縫製部７の少なくとも一部が、ガス発生器３からのガス供給量が所定量以上になると破断する様になっている。尚、ガス発生器３の装着については前述の通りであるので、その説明を省略する。
【００２１】
このエアバッグの展開形態について説明すると、先ず、衝突の程度が軽度の場合には前記２つのガス発生器の内の大容量の第一ガス発生器３１のみが作動し、図７に示す様に、前記内側基布８の内側の小空間Ｓのみを膨張させる。この時のガス供給量は、該小空間Ｓを膨張させ且つこれを維持させるには十分であるが、第三縫製部７を破断させるには不十分である点は前述の場合と同じである。
【００２２】
次に、衝突の程度が中程度と判断されると、前記２つのガス発生器３１，３２が、時間差をおいて点火される。これにより、先ず大容量の第一ガス発生器３１から供給されるガスによって小空間Ｓが穏やかに展開を開始し、続いて点火される第二ガス発生器３２のガスと合流した大量のガスによって小空間Ｓの内圧が上昇し、前記第三縫製部の一部に形成された弱い縫着力の部分７ａが破断して、図８に示す様に大空間Ｌを膨張させる事になる。又、衝突の程度が重大と判断された場合には、前記２つのガス発生器が同時に点火され、瞬時に大量に流入するガス圧によって前記第三縫製部７の破断部７ａが破断し、一気に大空間Ｌを膨張させる事になる。
【００２３】
次に、図９は、上記第三縫製部７の破断部７ａの形成例を示すもので、同図では、第三縫着部７を２本の縫製線７ｂ，７ｃで構成し、外側の縫製線７ｂは連続した縫製線となし、内側の縫製線７ｃは縫製されていない部分７ａを有する不連続な縫製線としている。これにより２本の縫製線７ｂ，７ｃで縫着された部分に比べ、不連続部７ａを有する部分の縫着力は弱くなっているので、この部分が破断部となる。この場合には、１本の縫製線７ｂでは、前記第一ガス発生器３１のみからのガス供給速度に基づく小空間Ｓ内のガス圧には耐えられるが、第一、第二ガス発生器３１，３２から同時にガスが供給された場合に発生する前記小空間Ｓ内の圧力には耐えられない様に、縫製線７ｂを構成する縫製糸を適宜選択する事になる。又、２本の縫製線７ｂ，７ｃが存在する部分は、前記２つガス発生器３１，３２から同時にガスが供給されても破断しない様になっている。尚、前記縫製線７ｃの不連続部、即ち破断部７ａは、少なくとも１ケ所必要であるが、裏側基布２の中心のガス発生器取付開口２ａに対して対象位置に均等に複数箇所形成しておくのが好ましい。
【００２４】
次に、図１０は、上記第三縫製部７の破断部７ａの他の形成例を示す概念図であり、裏側基布２と内側基布８との縫製線を１本の円周状の縫製線となし、その円周状の縫製過程で、部分的に縫製方向を逆行させた後に再び順行させるジグザグ運針を行う事により、重複縫製部７ｄを複数箇所に形成したものである。この場合にも、１本の縫製線の部分が破断部７ａとなり、該１本の縫製線では、前記第一ガス発生器３１からのガス圧には耐えられるが、２つのガス発生器３１，３２から同時に供給されるガス圧には耐えられない程度の縫製糸を用いて縫製する事は前述の場合と同様である。
【００２５】
又、前記内側基布８と裏側基布２との第三縫製部７の破断部７ａの位置は、基本的には任意であるが、エアバッグが乗員に向かって飛び出さない様にするために、表側基布１を乗員に向かう前後方向に膨張させるのではなく、左右方向に膨張させるのが好ましいので、前記破断部７ａは、エアバッグ展開状態における左右部に形成される様にするのが好ましい。
【００２６】
又、内側基布８と裏側基布２との第三縫製部７の縫製線が全て破断し、内側基布８が吹き飛んで、裏側基布２に形成されている内外のガス放出孔６ａ，６ｂを塞いだり、或いは、外側ガス放出孔６ｂが位置する側（エアバッグ展開状態における上方側）と反対側（エアバッグ展開状態における下方側）の縫製線が全て破断して、該破断部の内側基布１０が裏返って前記外側ガス放出孔６ｂを塞いだりするおそれがあるが、これを防止するには、前記縫製部７の外側ガス放出孔６ｂが位置する側と反対側、即ち該縫製部７の下側部が破断部７ａとならない様に、前述の二重縫製部や重複縫製部等を形成しておく事が好ましい。
【００２７】
尚、本発明で使用するエアバッグの基布としては、ガス発生器３から放出される高温のガスに接する小空間Ｓに面する側には、耐熱性が要求されるので、ガス発生器に面する内側基布８の内側及び裏側基布の内側中央部には、シリコン樹脂等の耐熱樹脂をコーティングを施した基布が使用され、乗員に接触する表側基布１は、小空間Ｓを経た後の冷却されたガスが流入するので、高い耐熱性は要求されない事になるから、表側基布１は無コーティング基布を使用する事が可能である。特に、ガス発生器の構造によっては、放出ガス温度が従来のものより低く抑える事も可能であるので、この様な場合或いは基布自体に耐熱繊維を用いている場合には、全ての基布を無コーティング布とする事も可能であり、特に、エアバッグのリサイクルの容易性の観点からは、無コーティング布が望ましい。更に、無コーティング布は、コーティング布に比べて柔らかいので、乗員がエアバッグに衝突した場合に生じ易い擦過傷を阻止する効果もある。
【００２８】
以上の実施例において説明した本発明のエアバッグは、運転席用或いは助手席用の円形のエアバッグであるが、本発明のエアバッグの形状はこれに限定されるのではなく、枕状の助手席用エアバッグ或いは楕円形の運転席／助手席用エアバッグにも適用できるものであり、特許請求の範囲の記載に基づいて種々の適用形態が存在する事は言うまでもない。
【００２９】
又、上記説明では、衝突の程度によるエアバッグの展開形態についての説明であるが、更に、乗員の着座位置や姿勢等の乗員条件を検知してエアバッグの展開形態を最適に制御する事も可能となる。例えば、乗員位置検知センサによって乗員の着座位置を検出し、乗員が車体に近い位置に着座している場合には、エアバッグを急速に強く展開させると、乗員を跳ね飛ばして傷害を与える可能性もあるので、この場合には、前記第一ガス発生器のみによる小空間Ｓのみを膨張させたり或いは２つのガス発生器の点火タイミングをずらして大空間Ｌを緩やかに膨張させて、乗員を穏やかに保護する事が可能となる。
【００３０】
又、乗員が前屈みに着座している場合と、シートに深く着座している場合とでは、同じ衝突でも乗員が車体に衝突する速度や時間が異なるので、着座センサや赤外線センサ或いは超音波センサ等によって乗員の姿勢を検知し、この姿勢情報によってエアバッグの展開形態を制御する事も可能である。例えば、乗員が前屈みの姿勢で着座している場合には、上述した乗員が車体に近い位置に着座している場合と同様に、エアバッグを急速に強く展開させると、乗員を跳ね飛ばして傷害を与えるおそれもあるので、前記第一ガス発生器のみによる小空間Ｓのみの膨張或いは２つのガス発生器の点火タイミングをずらして大空間Ｌを緩やかに膨張させる展開方式が採用される。
【００３１】
更に、乗員の体格（体重）が異なれば、これを衝突時の衝撃から保護すべきエアバッグの最適展開形態も異なるから、乗員の体格（体重）を、着座センサによって検知し、乗員の体格が小さい場合には、エアバッグの強い展開を避けて、小空間Ｓのみによる展開や大空間Ｌの緩やかな展開形態を採用する事により、体格の小さな乗員をエアバッグで跳ね飛ばす事なく安全に保護する事が可能となる。一方、体格の大きな乗員に対しては、軽度の衝突の場合でも大空間Ｌを緩やかに展開させる方式を選択する事により、体格にあった最適なエアバッグの展開形態を選択する事が可能となる。
【００３２】
【発明の効果】
以上説明した様に、本発明のエアバッグによれば、表側基布１と裏側基布２とを、周縁部と中間部の２ケ所で縫着する事により、或いは、両基布１，２の間に内側基布８を配置してその周縁部を裏側基布２と縫着する事により、内側の小空間Ｓとこれを含む外側の大空間Ｌとを形成し、衝突の程度に応じて、小空間Ｓのみを膨張させたり、大空間Ｌを膨張させたり、或いは、大空間Ｌの膨張速度を制御する事が可能となる。
【００３３】
この結果、衝突センサにより衝突の程度を判定して、最適な形態でエアバッグを展開させる事が可能となるので、従来の画一的なエアバッグの展開形態によってもたらされていた乗員への傷害が著しく軽減される事になる。
【００３４】
更に、衝突の軽重のみならず、乗員の着座位置や姿勢或いは体格を検知してエアバッグの展開形態を最適に制御する事も可能となる。この結果、衝突の軽重，乗員の着座位置，姿勢，体格に応じて、最適なエアバッグの展開形態を実現する事が可能となる。
【図面の簡単な説明】
【図１】本発明に係るエアバッグの第一のタイプの実施例を示す背面平面図である。
【図２】図１のＩ−Ｉ断面図である。
【図３】図１のエアバッグの小空間の膨張状態を示す断面図である。
【図４】図１のエアバッグの大空間の膨張状態を示す断面図である。
【図５】本発明に係るエアバッグの第二のタイプの実施例を示す背面平面図である。
【図６】図５のＩＩ−ＩＩ断面図である。
【図７】図５のエアバッグの小空間の膨張状態を示す断面図である。
【図８】図５のエアバッグの大空間の膨張状態を示す断面図である。
【図９】本発明の第二のタイプのエアバッグの第三縫製部の他の実施例を示す背面平面図である。
【図１０】本発明の第二のタイプのエアバッグの第三縫製部の他の実施例を示す縫製線の概略図である。
【図１１】本発明で使用するガス発生器の１例を示す断面図である。
【図１２】従来のエアバッグの展開状態を示す断面図である。
【符号の説明】
１表側基布
２裏側基布
２ａガス発生器取付開口
３ガス発生器
４第一縫製部
５第二縫製部
６ａ内側ガス放出孔
６ｂ外側ガス放出孔
７第三縫製部
７ａ破断部
８内側基布
３１第一ガス発生器
３２第二ガス発生器
Ｓ小空間
Ｌ大空間[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an airbag used in an airbag device for securing an occupant from an impact at the time of a collision of an automobile, and in particular, an airbag that can change the deployment form of the airbag due to the weight of the collision. Concerning structure.
[0002]
As shown in FIG. 12, a typical structure of a conventional airbag is a backside base fabric 2 having a front side base fabric 1 located on the passenger side and a gas generator mounting opening 2a for mounting the gas generator 3. And the peripheral portions of both base fabrics 1 and 2 are sewn by the sewing portion 4 and formed into a bag shape. The gas generator 3 is inserted into the gas generator mounting opening 2a of the back side base fabric 2 of the airbag A, and the flange 3a of the gas generator 3 and the opening peripheral edge 2b of the back side base fabric 2 are connected to each other. It is fixed by fixing means 9 such as bolts. When the airbag A is deployed, the airbag A is inflated between the occupant and the vehicle body in a very short time due to the high-pressure gas rapidly discharged from the gas discharge port 3b of the gas generator 3, and the occupant It will alleviate collisions with the car body.
[0003]
By the way, the deployment of the airbag A is designed so that when a collision is detected by a collision sensor installed at an appropriate position of the vehicle body, the airbag A is rapidly deployed regardless of the weight of the collision. For this reason, in a relatively light collision, an occupant is blown off by the rapidly expanding airbag's inflating force and injured, or in a very serious collision, the deployment speed of the airbag is too slow. May result in incomplete protection of the passenger. In addition, the airbag is always deployed under certain conditions regardless of the posture and position of the occupant. Therefore, when the occupant is seated at a position close to the airbag, the airbag will jump by deployment. There are also situations where they are skipped.
[0004]
Therefore, recently, a so-called smart airbag system has been proposed in which the weight of a collision or the posture and position of an occupant is detected to control the deployment form of the airbag. Specifically, it is a method of deploying one airbag using two gas generators, and adjusting the ignition timing of the two gas generators according to the weight of the collision, the posture of the occupant, etc. Alternatively, the air bag deployment mode is controlled by operating only one of the gas generators.
[0005]
[Problems to be solved by the invention]
In such a smart airbag system, since the volume of the airbag itself is constant, even if an attempt is made to deploy the airbag with a small amount of gas, there is a risk that the deployment of the airbag will be insufficient and cause injury to the occupant. In addition, even if the airbag is required to be deployed within a short time after the collision, there is a limit to the gentle deployment of the airbag by increasing the ignition time difference.
[0006]
In view of the above circumstances, an object of the present invention is to provide an optimal airbag for the smart airbag system by changing the deployment capacity of the airbag itself.
[0007]
[Means for Solving the Problems]
The present invention has been made in order to solve the above-described problem, and is an airbag for an occupant protection device in which a deployment form is changed according to the amount of gas supplied from the gas generator 3. A first sewing portion 4 formed by sewing the peripheral portions of the front side base fabric 1 and the back side base fabric 2 having the gas generator mounting opening 2a to each other; the front side base fabric 1 and the back side base fabric 2; A third sewing portion 7 formed by sewing a peripheral edge portion of the inner base fabric 8 disposed between the back side base fabric 2 and an inner side of the third sewing portion 7 of the back side base fabric 2. An inner gas discharge hole 6a and an outer gas discharge hole 6b are formed between the third sewing portion 7 and the first sewing portion 4, respectively, and the amount of gas supplied from the gas generator 3 is as follows. In the case of a predetermined amount or less, only the small space S formed inside the inner base fabric 8 is expanded, and the gas supply Exceeds the predetermined amount, the third sewing portion 7 is broken to expand the large space L formed by the front side base fabric 1 and the back side base fabric 2, and at least the third sewing portion 7 A rupture portion 7a having a weak sewing force is formed in the sewing portion 7 so that the portion 7a breaks when the predetermined gas supply amount is exceeded, and the rupture portion 7a of the third sewing portion 7 includes: A plurality of positions are formed at symmetrical positions with respect to the gas generator mounting opening 2a of the backside base fabric 2.
[0009]
As described above, a small space and a large space are formed in the airbag, and any space can be inflated according to the weight of the collision or the posture of the occupant protection device. Is. Which of the two spaces is expanded can be selected by igniting one or both of the two gas generators. That is, the boundary between the large and small spaces is configured to break when the amount of gas supplied into the airbag exceeds a predetermined amount, and gas is supplied from the small space to the large space, so that the large space is inflated. Yes.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view (rear view) showing a first airbag according to the present invention, and FIG. 2 is a sectional view taken along the line II. In the figure, an airbag A is formed by integrally sewing a front side base fabric 1 and a back side base fabric 2 by a first sewing portion 4 formed along a peripheral portion thereof. The intermediate position 2 is also sewn by the second sewing portion 5. A gas generator mounting opening 2a is formed in the approximate center of the back base fabric 2, and between the first sewing portion 4 and the second sewing portion 5 and inside the second sewing portion 5, An outer gas discharge hole 6b and an inner gas discharge hole 6a are respectively formed.
[0011]
A gas generator 3 is inserted into the gas generator mounting opening 2a as shown in FIG. 2, and the flange 3a of the gas generator and the peripheral edge 2b of the opening of the back side base fabric 2 are connected to a bolt or the like as in the prior art. It is fixed by the fixing means 9. Reference numeral 2 c denotes an insertion hole for the fixing means 9 formed in the back side base fabric 2.
[0012]
Next, an example of the structure of the gas generator 3 used in the present invention will be described with reference to FIG. FIG. 11 shows a cross section of a short cylindrical gas generator used in a normal driver's seat airbag. The gas generator 3 has a large capacity inside a cylindrical housing 21 by a partition member 22. The gas generator is divided into two gas generators, a first gas generator 31 and a small-capacity second gas generator 32, and includes two gas generators having different capacities. In each of the gas generators 31 and 32, an ignition device 25 for igniting the gas generating agent 23 in each gas generator is disposed together with the gas generating agent 23 and the filter 24 as usual. It is configured to operate. Therefore, even if one of the gas generators is activated, the insulation between the partition member and the filter is appropriately heat-treated so that the other gas generator is not burned by the high temperature gas generated there. Needless to say. Further, in the circumferential direction of the housing 21, an appropriate number of gas discharge ports 3b are formed at positions corresponding to the respective gas generators. The ratio of gas generation capacity between the large-capacity gas generator 31 and the small-capacity gas generator 32 is set in a range of about 6: 4 to 8: 2.
[0013]
The operation of the gas generator 3 will be described. The following three types of ignition modes are instructed to the gas generators 31 and 32 based on the determination of the collision weight from the collision sensor.
(A) Only the large capacity first gas generator 31 is ignited.
(B) First, the large-capacity first gas generator 31 is ignited, and the small-capacity second gas generator is ignited with a small ignition time difference.
(C) The two gas generators 31 and 32 are ignited simultaneously.
In terms of the lightness of the collision, these ignition modes are as follows: (a) is a case of a light collision, (b) is a medium collision, and (c) is a development of a serious collision. It can be said that it is a form.
[0014]
FIG. 11 shows an example of a short cylindrical gas generator. As a gas generator applicable to the airbag of the present invention, a long cylindrical gas generator is provided with a partition member in the longitudinal direction. However, in any case, the shape and structure of the gas generator used in the present invention are not limited.
[0015]
Next, the deployment form of the airbag A by the gas generator will be described with reference to FIGS. A collision sensor located at the right position of the vehicle body detects the collision of the vehicle, and the degree of the collision is calculated by the arithmetic unit to calculate whether the collision is a serious collision or a minor collision. Then, only the first gas generator 31 having a large capacity is ignited, gas is released into the airbag from the gas discharge port 3b of the gas generator, and the front base fabric 1 and the back side base are placed inside the second sewing portion 5. The small space S formed by the cloth 2 expands, and excess gas is discharged to the outside from the inner gas discharge hole 6a formed inside the second sewing portion 5 while maintaining the expansion of the small space S. Will be done. In this way, the airbag is gently deployed only by the supply gas from the first gas generator 31 having a relatively low gas supply speed in the small space S as compared with the conventional airbag, and Will be reliably protected against minor collisions.
[0016]
Here, the gas supply speed discharged from the first gas generator 31 is necessary and sufficient to expand the small space S and maintain it for a predetermined time while the gas is discharged from the gas discharge hole 6a. The gas supply amount is set to an amount that is insufficient to generate a high internal pressure that breaks the sewing line of the second sewing portion 5. In other words, it can be said that the second sewing portion is sewn with a strength that does not break with the gas supply amount supplied from the first gas generator 31.
[0017]
Further, when the arithmetic unit determines that the degree of collision is moderate and it is determined that the expansion of the small space S is not sufficient, the ignition timings of the two gas generators 31 and 32 are shifted to perform ignition. To do. That is, the first gas generator 31 having a large capacity is first ignited, the small space S of the airbag is inflated in the manner described above, and then the second gas generator 32 having a small capacity is ignited after a predetermined minute time. . When the second gas generator 32 is ignited, the gas generated from the two gas generators is supplied into the small space S at the same time. The balance of the amount of gas discharged from the discharge hole 6a is lost, the internal pressure in the small space S rises, the sewing line of the second sewing portion 5 breaks, and as shown in FIG. The large space L formed in the first sewing portion 4 at the periphery of the backside base fabric 2 expands, and excess gas is released to the outside from both the inner gas discharge hole 6a and the outer gas discharge hole 6b. The expansion of the large space L is maintained for a predetermined time. In this way, the airbag first gently expands the small space S with only the supply gas from the first gas generator 31, and then rapidly expands with the supply gas from both the gas generators 31 and 32. It will protect the occupant from hitting the car body softly.
[0018]
Here, the sewing strength of the second sewing portion 5 is not broken by the gas generation amount of the first gas generator 31, but the gas from the first and second gas generators 31 and 32 is supplied simultaneously. In some cases, it can be said that the strength is set so as to break.
[0019]
Next, when it is determined by the arithmetic unit that the degree of collision is serious, the ignition devices of the two gas generators 31 and 32 are simultaneously operated, and a large amount of gas is air-released from the gas discharge port 3b. It will be supplied to the bag at once. In this case, the gas from the gas generator first flows into the small space S. Since a large amount of gas is simultaneously supplied from the first and second gas generators, the internal pressure in the small space S is As a result, the second sewing portion 5 is instantly broken and the large space L is rapidly inflated, and an airbag is deployed between the occupant rapidly moving toward the vehicle body and the occupant. Will be protected.
[0020]
Next, a second type airbag of the present invention will be described with reference to FIGS. FIG. 5 is a plan view (rear view) of a second type airbag of the present invention, and FIG. 6 is a sectional view taken along line II-II. This second type airbag differs from the first type airbag in that an inner base fabric 8 is disposed between the front side base fabric 1 and the back side base fabric 2. In this airbag, the front side base fabric 1 and the back side base fabric 2 have their peripheral edges sewn by the first sewing portion 4, and the inner base fabric 8 is attached to the gas generator formed on the back side base fabric 2. It arrange | positions so that the opening 2a may be covered, The peripheral part is sewn on by the back side base fabric 2 and the 3rd sewing part 7. FIG. Thereby, a small space S is formed inside the third sewing portion 7, and a large space L is formed inside the first sewing portion 4. Further, an inner gas discharge hole 6a that opens into the small space S is formed inside the third sewing portion 7 of the back side base fabric 2, and further, between the first sewing portion 4 and the third sewing portion 7, The outer gas discharge hole 6b that opens to the large space L is formed in the same manner as the case described above. Further, at least a part of the third sewing portion 7 is broken when the gas supply amount from the gas generator 3 exceeds a predetermined amount. The mounting of the gas generator 3 is as described above, and the description thereof is omitted.
[0021]
Referring to the deployment form of the airbag, first, when the degree of collision is slight, only the large-capacity first gas generator 31 of the two gas generators operates, as shown in FIG. Only the small space S inside the inner base fabric 8 is expanded. The amount of gas supplied at this time is sufficient to expand and maintain the small space S, but is insufficient to break the third sewing portion 7 as in the case described above. .
[0022]
Next, when it is determined that the degree of collision is moderate, the two gas generators 31 and 32 are ignited with a time difference. Thereby, first, the small space S starts to unfold gently by the gas supplied from the large-capacity first gas generator 31, and then the large amount of gas merged with the gas of the second gas generator 32 that is ignited. The internal pressure of the small space S rises, the weak sewing force portion 7a formed in a part of the third sewing portion breaks, and the large space L is expanded as shown in FIG. If it is determined that the degree of collision is serious, the two gas generators are simultaneously ignited, and the breaking portion 7a of the third sewing portion 7 is broken by the gas pressure that flows in a large amount instantaneously. The large space L will be expanded.
[0023]
Next, FIG. 9 shows an example of formation of the breaking portion 7a of the third sewing portion 7. In FIG. 9, the third sewing portion 7 is constituted by two sewing lines 7b and 7c, The sewing line 7b is a continuous sewing line, and the inner sewing line 7c is a discontinuous sewing line having an unsewn portion 7a. Thereby, compared with the part sewn by the two sewing lines 7b and 7c, the sewing force of the part which has the discontinuous part 7a is weak, Therefore This part turns into a fracture | rupture part. In this case, one sewing line 7 b can withstand the gas pressure in the small space S based on the gas supply speed from only the first gas generator 31, but the first and second gas generators 31. , 32, the sewing thread constituting the sewing line 7b is appropriately selected so that it cannot withstand the pressure in the small space S that is generated when gas is supplied simultaneously. Further, the portion where the two sewing lines 7b and 7c are present is not broken even if gas is supplied simultaneously from the two gas generators 31 and 32. At least one discontinuous portion of the sewing line 7c, that is, the broken portion 7a, is required, but a plurality of portions are formed evenly at the target position with respect to the gas generator mounting opening 2a at the center of the back base fabric 2. It is preferable to keep it.
[0024]
Next, FIG. 10 is a conceptual diagram showing another example of formation of the rupture portion 7a of the third sewing portion 7, and the sewing line between the back side base fabric 2 and the inner side base fabric 8 is formed into one circumferential shape. By forming a sewing line and performing zigzag hand movement in which the sewing direction is partially reversed in the circumferential sewing process, the overlapping sewing portions 7d are formed at a plurality of locations. Also in this case, a portion of one sewing line becomes the fracture portion 7a, and the one sewing line can withstand the gas pressure from the first gas generator 31, but the two gas generators 31, Sewing using a sewing thread that cannot withstand the gas pressure supplied simultaneously from 32 is the same as described above.
[0025]
Further, the position of the breaking portion 7a of the third sewing portion 7 between the inner base fabric 8 and the back base fabric 2 is basically arbitrary, but in order to prevent the airbag from jumping toward the occupant. In addition, since it is preferable to inflate the front base fabric 1 in the left-right direction rather than in the front-rear direction toward the occupant, the breaking portion 7a is formed at the left and right portions in the airbag deployment state. Is preferred.
[0026]
Further, all of the sewing lines of the third sewing portion 7 between the inner base fabric 8 and the rear base fabric 2 are broken, and the inner base fabric 8 is blown off, so that the inner and outer gas discharge holes 6a, 6b is closed, or all of the sewing lines on the opposite side (upper side in the airbag deployment state) where the outer gas discharge hole 6b is located (upper side in the airbag deployment state) are ruptured. The inner base fabric 10 may turn over and block the outer gas discharge hole 6b. To prevent this, in order to prevent this, the side opposite to the side where the outer gas discharge hole 6b is located, that is, the sewing is performed. It is preferable to form the above-described double sewing portion, overlapping sewing portion, or the like so that the lower portion of the portion 7 does not become the fracture portion 7a.
[0027]
In addition, as a base fabric of the airbag used by this invention, since heat resistance is requested | required by the side facing the small space S which contact | connects the high temperature gas discharge | released from the gas generator 3, a gas generator is used. A base fabric coated with a heat-resistant resin such as a silicone resin is used on the inner side of the inner base fabric 8 and the inner center portion of the back side base fabric, and the front side base fabric 1 in contact with the occupant has a small space S. Since the cooled gas flows after the passage, high heat resistance is not required, so that the front side base fabric 1 can use an uncoated base fabric. In particular, depending on the structure of the gas generator, the emitted gas temperature can be kept lower than the conventional one. In such a case or when heat resistant fibers are used for the base fabric itself, all base fabrics are used. Can be used as an uncoated cloth. In particular, from the viewpoint of easy recycling of an airbag, an uncoated cloth is desirable. Furthermore, since the uncoated cloth is softer than the coated cloth, it has an effect of preventing scratches that are likely to occur when an occupant collides with the airbag.
[0028]
The airbag of the present invention described in the above embodiments is a circular airbag for a driver seat or a passenger seat, but the shape of the airbag of the present invention is not limited to this, and is a pillow-shaped airbag. The present invention can also be applied to an airbag for a passenger seat or an elliptical driver seat / passenger seat airbag, and it goes without saying that various application forms exist based on the description of the scope of claims.
[0029]
In the above description, the airbag deployment mode is described according to the degree of collision. However, the airbag deployment mode may be optimally controlled by detecting the passenger conditions such as the seating position and posture of the passenger. It becomes possible. For example, if the occupant's seating position is detected by the occupant position detection sensor and the occupant is seated at a position close to the vehicle body, if the airbag is deployed rapidly and strongly, the occupant may jump off and cause injury. Therefore, in this case, the small space S only by the first gas generator is expanded, or the large space L is gently expanded by shifting the ignition timing of the two gas generators, so that the occupant is gently It becomes possible to protect.
[0030]
Also, when the occupant is seated forward and deeply seated, the speed and time at which the occupant collides with the vehicle body is different even in the same collision, so a seating sensor, infrared sensor, ultrasonic sensor, etc. It is also possible to detect the posture of the occupant and to control the airbag deployment form based on this posture information. For example, when the occupant is seated in a forward-bent posture, as in the case where the occupant is seated close to the vehicle body as described above, if the airbag is rapidly deployed strongly, the occupant will jump off and be injured. Therefore, the expansion method of expanding only the small space S by the first gas generator alone or gradually expanding the large space L by shifting the ignition timing of the two gas generators is adopted.
[0031]
Furthermore, if the occupant's physique (weight) is different, the optimum deployment form of the airbag that should be protected from the impact at the time of collision also differs, so the occupant's physique (weight) is detected by a seating sensor, In small cases, avoiding strong deployment of airbags and adopting a deployment with only a small space S or a gentle deployment with a large space L, it is possible to safely protect small occupants without jumping off with an airbag. It becomes possible to do. On the other hand, for passengers with large physiques, it is possible to select the optimal airbag deployment configuration that fits the physique by selecting a method that gently expands the large space L even in the event of a minor collision. Become.
[0032]
【The invention's effect】
As described above, according to the airbag of the present invention, the front side base fabric 1 and the back side base fabric 2 are sewn at the two positions of the peripheral portion and the middle portion, or both the base fabrics 1 and 2 are sewn. The inner base cloth 8 is arranged between the two and the peripheral edge is sewn to the back base cloth 2, thereby forming an inner small space S and an outer large space L including the inner space. Thus, it is possible to expand only the small space S, expand the large space L, or control the expansion speed of the large space L.
[0033]
As a result, the degree of collision can be determined by the collision sensor, and the airbag can be deployed in an optimal form. Injury will be significantly reduced.
[0034]
Furthermore, it is possible to optimally control the deployment form of the airbag by detecting not only the weight of the collision but also the seating position, posture or physique of the occupant. As a result, it is possible to realize an optimal airbag deployment form according to the collision weight, the occupant's seating position, posture, and physique.
[Brief description of the drawings]
FIG. 1 is a rear plan view showing an embodiment of a first type of airbag according to the present invention.
FIG. 2 is a cross-sectional view taken along the line II of FIG.
3 is a cross-sectional view showing an inflated state of a small space of the airbag of FIG. 1. FIG.
4 is a cross-sectional view showing an expanded state of a large space of the airbag of FIG. 1. FIG.
FIG. 5 is a rear plan view showing a second type of embodiment of the airbag according to the present invention.
6 is a cross-sectional view taken along the line II-II in FIG.
7 is a cross-sectional view showing an inflated state of a small space of the airbag of FIG. 5. FIG.
8 is a cross-sectional view showing an expanded state of a large space of the airbag of FIG.
FIG. 9 is a rear plan view showing another embodiment of the third sewing portion of the second type airbag of the present invention.
FIG. 10 is a schematic diagram of a sewing line showing another embodiment of the third sewing portion of the second type airbag of the present invention.
FIG. 11 is a cross-sectional view showing an example of a gas generator used in the present invention.
FIG. 12 is a cross-sectional view showing a deployed state of a conventional airbag.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Front side base fabric 2 Back side base fabric 2a Gas generator installation opening 3 Gas generator 4 First sewing part 5 Second sewing part 6a Inner gas discharge hole 6b Outer gas discharge hole 7 Third sewing part 7a Breaking part 8 Inner base cloth 31 1st gas generator 32 2nd gas generator S Small space L Large space

Claims

An airbag for an occupant protection device in which a deployment form is changed according to the amount of gas supplied from the gas generator (3),
  A first sewing portion (4) formed by sewing peripheral edges of a front side base fabric (1) positioned on the passenger side and a back side base fabric (2) having a gas generator mounting opening (2a); Third sewing portion (7) formed by sewing the peripheral portion of the inner base fabric (8) disposed between the front base fabric (1) and the back base fabric (2) to the back base fabric (2). And
  An inner gas discharge hole (6a) is provided inside the third sewing portion (7) of the back side base fabric (2), and between the third sewing portion (7) and the first sewing portion (4). Outer gas discharge holes (6b) are respectively formed in
  When the gas supply amount from the gas generator (3) is a predetermined amount or less, only the small space (S) formed inside the inner base fabric (8) is expanded,
  When the gas supply amount exceeds a predetermined amount, the third sewing portion (7) is broken and the large space (L) formed by the front side base fabric (1) and the back side base fabric (2) is expanded. And let
  A rupture part (7a) having a weak sewing force is formed in the sewing part (7) so that at least a part (7a) of the third sewing part (7) breaks when the predetermined gas supply amount is exceeded. And
  The breaking portion (7a) of the third sewing portion (7) is formed at a plurality of positions symmetrically with respect to the gas generator mounting opening (2a) of the back side base fabric (2). Air bag for occupant protection device

An airbag for an occupant protection device in which a deployment form is changed according to the amount of gas supplied from the gas generator (3),
  A first sewing portion (4) formed by sewing peripheral edges of a front side base fabric (1) positioned on the passenger side and a back side base fabric (2) having a gas generator mounting opening (2a); Third sewing portion (7) formed by sewing the peripheral portion of the inner base fabric (8) disposed between the front base fabric (1) and the back base fabric (2) to the back base fabric (2). And
  An inner gas discharge hole (6a) is provided inside the third sewing portion (7) of the back side base fabric (2), and between the third sewing portion (7) and the first sewing portion (4). Outer gas discharge holes (6b) are respectively formed in
  When the gas supply amount from the gas generator (3) is a predetermined amount or less, only the small space (S) formed inside the inner base fabric (8) is expanded,
  When the gas supply amount exceeds a predetermined amount, the third sewing portion (7) is broken and the large space (L) formed by the front side base fabric (1) and the back side base fabric (2) is expanded. And let
  A rupture part (7a) having a weak sewing force is formed in the sewing part (7) so that at least a part (7a) of the third sewing part (7) breaks when the predetermined gas supply amount is exceeded. And
  The third sewing part (7) is composed of a plurality of sewing lines (7b, 7c), a part of the sewing lines (7b) is a continuous sewing line, and the remaining part is a discontinuous sewing line (7c). None, the discontinuous portion is used as the breaking portion (7a), and the airbag for an occupant protection device is provided.

The third sewing part (7) is composed of a plurality of sewing lines (7b, 7c), a part of the sewing lines (7b) is a continuous sewing line, and the remaining part is a discontinuous sewing line (7c). None, The airbag for an occupant protection device according to claim 1, wherein the discontinuous portion is the fracture portion (7 a).

An airbag for an occupant protection device in which a deployment form is changed according to the amount of gas supplied from the gas generator (3),
  A first sewing portion (4) formed by sewing peripheral edges of a front side base fabric (1) positioned on the passenger side and a back side base fabric (2) having a gas generator mounting opening (2a); Third sewing portion (7) formed by sewing the peripheral portion of the inner base fabric (8) disposed between the front base fabric (1) and the back base fabric (2) to the back base fabric (2). And
  Inside gas (6b) is formed inside the third sewing part (7) of the back side base fabric (2), respectively.
  When the gas supply amount from the gas generator (3) is a predetermined amount or less, only the small space (S) formed inside the inner base fabric (8) is expanded,
  When the gas supply amount exceeds a predetermined amount, the third sewing portion (7) is broken and the large space (L) formed by the front side base fabric (1) and the back side base fabric (2) is expanded. And let
  A rupture part (7a) having a weak sewing force is formed in the sewing part (7) so that at least a part (7a) of the third sewing part (7) breaks when the predetermined gas supply amount is exceeded. And
  The third sewing part (7) is constituted by one circumferential sewing line, and an overlapping part of the sewing line is formed in a part thereof, whereby a non-overlapping part becomes the breaking part. Air bag for occupant protection device

The said 3rd sewing part (7) is comprised by one circumferential sewing line, and forms the duplication part of a sewing line in the part, The non-overlapping part becomes the said fracture | rupture part. Airbag for passenger protection device as described

6. The overlapping portion is formed by zigzag sewing (7 d) in which the sewing direction is partially reversed in the middle of the sewing line of the third sewing portion (7) and then forwardly moved again. 7. Air bag for passenger protection device as described in

The airbag for an occupant protection device according to any one of claims 1 to 6, wherein the breaking portion (7a) of the sewing portion (7) is formed on the left and right when the airbag is deployed.

The airbag for an occupant protection device according to any one of claims 1 to 6, wherein the breaking portion (7a) of the sewing portion (7) is formed at an upper portion when the airbag is deployed.

An airbag for an occupant protection device in which a deployment form is changed according to the amount of gas supplied from the gas generator (3),
  A first sewing portion (4) formed by sewing peripheral edges of a front side base fabric (1) positioned on the passenger side and a back side base fabric (2) having a gas generator mounting opening (2a); Third sewing portion (7) formed by sewing the peripheral portion of the inner base fabric (8) disposed between the front base fabric (1) and the back base fabric (2) to the back base fabric (2). And
  An inner gas discharge hole (6a) is provided inside the third sewing portion (7) of the back side base fabric (2), and between the third sewing portion (7) and the first sewing portion (4). Outer gas discharge holes (6b) are respectively formed in
  When the gas supply amount from the gas generator (3) is a predetermined amount or less, only the small space (S) formed inside the inner base fabric (8) is expanded,
  When the gas supply amount exceeds a predetermined amount, the third sewing portion (7) is broken and the large space (L) formed by the front side base fabric (1) and the back side base fabric (2) is expanded. And let
  The side facing the gas generator mounting opening (2a) of the inner base fabric (8) is provided with a heat resistant resin coating, and the front side base fabric (1) is formed of an uncoated fabric. Air bag for occupant protection device

A rupture part (7a) having a weak sewing force is formed in the sewing part (7) so that at least a part (7a) of the third sewing part (7) breaks when the predetermined gas supply amount is exceeded. The air bag for an occupant protection device according to claim 9

The side facing the gas generator mounting opening (2a) of the inner base fabric (8) is provided with a heat resistant resin coating, and the front base fabric (1) is formed of an uncoated fabric. The airbag for an occupant protection device according to any one of 8

The airbag for an occupant protection device according to any one of claims 1 to 11, wherein the first sewing portion (4) is exposed to the outside.

An airbag in which one airbag is inflated by two gas generators (31, 32) having different gas generation amounts, and the ratio of the gas generation amounts of the two gas generators is 6: 4 to The ratio is 8: 2, and only the small space (S) is expanded by operating a large capacity gas generator, and the large space (L) is expanded by operating both gas generators. Item 14. The airbag for an occupant protection device according to any one of Items 1 to 12.