JP3762531B2

JP3762531B2 - Variable throttle valve

Info

Publication number: JP3762531B2
Application number: JP34430297A
Authority: JP
Inventors: 晃久梅谷
Original assignee: JTEKT Corp
Current assignee: JTEKT Corp
Priority date: 1997-11-28
Filing date: 1997-11-28
Publication date: 2006-04-05
Anticipated expiration: 2017-11-28
Also published as: JPH11157457A

Description

【０００１】
【発明の属する技術分野】
本発明は、スプールの軸方向変位に伴い開度が変化する絞り部を備える可変絞り弁に関する。
【０００２】
【従来の技術と発明が解決しようとする課題】
油圧パワーステアリング装置においては、車速等の運転条件に応じて開度が変化する絞り部を有する可変絞り弁を用い、運転条件に応じて操舵補助力発生用油圧アクチュエータに作用する油圧を制御している。
【０００３】
例えば、ハウジングに軸方向移動可能に挿入されるスプールにねじ合わされるネジ部材をモータにより回転駆動し、そのネジ部材の回転によるスプールの軸方向移動によって開度が変化する絞り部を備える可変絞り弁が用いられている。
【０００４】
その絞り部の開度制御を精密に行なうため、スプールのハウジングに対する相対回転を阻止する必要がある。その相対回転を阻止するため、回り止め部材を設けたり、スプールとハウジングとに相対回転しないように互いに接する部分を形成したり、スプールの軸心とネジ部材の軸心とを偏心させることが行われている。
【０００５】
しかし、その相対回転阻止のために回り止め部材を設けたり、スプールとハウジングとに互いに接する部分を形成すると、コストおよび加工、組み立て工数を増大させる。スプールの軸心とネジ部材の軸心とを偏心させると、ねじ部材の回転によりスプールの外周を挿入孔の内周に押し付ける力が作用する。その押し付け力に基づく摩擦によりスプールの変位が阻害されるという問題がある。
【０００６】
また、ハウジングに形成された挿入孔内におけるスプールの回転により、その挿入孔の内周とスプールの外周との間の絞り部の開度を変更可能な可変絞り弁が用いられている。そのような回転スプールを用いる場合、ネジ部材やスプールのネジ加工が不要になる。
【０００７】
しかし、従来の回転スプールはモータの回転シャフトにより一点で支持されるか、若しくはシールリングを介して挿入孔の内面により支持されている。そのように一点で支持されるスプールは振れ回り易く、挿入孔の内面との間の摩擦により回転が阻害されるという問題がある。また、シールリングを介して挿入孔の内面により支持さるスプールは、シールリングの締め付け力により回転が阻害されたり、シールリングが変形して振れ回りが生じて挿入孔の内面との間の摩擦により回転が阻害されるという問題がある。
【０００８】
その回転スプールとして貫通孔を有するものを用いる場合、その挿入孔の内周に圧油導入用の凹部を形成し、スプールの外周に圧油排出用の凹部を形成し、その圧油排出用凹部と貫通孔とを通孔を介して連絡し、その圧油導入用凹部と圧油排出用凹部との間を絞り部としている。この場合、圧油は、その貫通孔からスプールの軸方向外方に導かれるため、圧油の排出路をスプールの軸方向外方に形成する必要がある。そのため、可変絞り弁の軸方向寸法が大きくなるという問題がある。
【０００９】
その回転スプールとして中実のものを用いる場合、その挿入孔の内周に圧油導入用の凹部と、圧油排出用の凹部とを形成し、その圧油導入用凹部と圧油排出用凹部との中間においてスプールの外周に凹部を形成し、その圧油導入用凹部と圧油排出用凹部との間を絞り部としている。この場合、絞り部の数に対して必要とされる挿入孔の内周とスプールの外周とに形成される凹部の数が多くなるため、可変絞り弁の周方向寸法が大きくなるという問題がある。また、その周方向寸法を小さくするために絞り部の数を少なくすると、各絞り部における圧油流量が多くなり、キャビテーション気泡発生に起因する流動音が大きくなるという問題がある。
【００１０】
その回転スプールを用いる場合、絞り部の開度制御を精密に行うためには、スプールの基準位置を精密に設定する必要がある。しかし、スプールの回転により絞り部の開度を変更可能な従来の可変絞り弁においては、スプールの基準位置を調節する手段は開示されていない。
【００１１】
本発明は、上記問題を解決することのできる可変絞り弁を提供することを目的とする。
【００１２】
【課題を解決するための手段】
本発明の可変絞り弁は、ハウジングと、このハウジングに形成された挿入孔に軸中心に回転可能に挿入されるスプールと、そのスプールを回転駆動するモータと、そのスプールの回転によって開度が変化する絞り部と、そのスプールを、軸方向に離れた２位置において支持する軸受とを備えることを特徴とする。
本発明の構成によれば、スプールを回転させることで絞り部の開度を変化させるので、モータの出力軸の回転運動を直線運動に変換するためのネジ部材やスプールのネジ加工を必要としない。そのスプールは軸方向に離れた２位置において軸受により支持されるので、振れ回りが抑制される。これにより、スプールの外周が挿入孔の内周に押し付けられることにより発生する摩擦を抑制し、スプールの作動不良やロックを防止できる。
【００１３】
そのスプールの内部に圧油室が形成され、そのスプールの外周に、その圧油室に通じる開口が形成され、その挿入孔の内周に、そのスプールの外周に対向する圧油排出用の凹部が形成され、その圧油排出用凹部と前記開口との間が前記絞り部とされ、そのハウジングに、その開口に通じる圧油導入路と、その圧油排出用凹部に通じる圧油排出路とが形成されているのが好ましい。
この構成によれば、スプールの両端間において圧油の導入と排出とを行えるので、可変絞り弁の軸方向寸法を小さくすることができる。
【００１４】
そのスプールの外周の開口と挿入孔の内周の圧油排出用凹部は、前記スプールの周方向に間隔をおいた複数位置に形成されているのが好ましい。
この構成によれば、絞り部の数に対して必要とされる開口と圧油排出用凹部の数を可及的に少なくできるので、可変絞り弁の周方向寸法を小さくでき、しかも、絞り部の数を多くすることで、各絞り部における圧油流量を少なくし、キャビテーション気泡発生に起因する流動音を低減できる。
【００１５】
そのハウジングにねじ合わされる基準位置設定部材を備え、その基準位置設定部材と前記スプールとの接触位置を基準位置として、そのスプールの回転角度に応じて前記絞り部の開度が制御可能とされ、その基準位置設定部材のハウジングに対するねじ込み量を変化させることで、その基準位置は変更可能とされているのが好ましい。
この構成によれば、基準位置設定部材とスプールとの接触位置を基準として、絞り部の開度制御を行うことができる。その基準位置は、基準位置設定部材のハウジングに対するねじ込み量を変化させることで調節できる。これにより、その絞り部の開度を精密に制御できる。
【００１６】
その絞り部の開度は車両の運転条件に応じて変化可能とされ、その絞り部の開度変化により、その車両の油圧パワーステアリング装置の操舵補助力発生用油圧アクチュエータに作用する油圧を制御可能であるのが好ましい。
これにより、車速等の運転条件に応じてスプールを回転させ、絞り部の開度を変化させることで、操舵補助力発生用油圧アクチュエータに作用する油圧を制御し、所望の操舵特性を得ることができる油圧パワーステアリング装置を構成できる。
【００１７】
【発明の実施の形態】
以下、図面を参照して本発明の実施形態を説明する。
【００１８】
図１に示すラックピニオン式油圧パワーステアリング装置１は、ステアリングホイール（図示省略）に連結される入力シャフト２と、この入力シャフト２にトーションバー６を介し連結される出力シャフト３とを備えている。そのトーションバー６は、ピン４により入力シャフト２に連結され、セレーション５により出力シャフト３に連結されている。その入力シャフト２は、ベアリング８を介しバルブハウジング７により支持され、また、ブッシュ１２を介して出力シャフト３により支持されている。その出力シャフト３はベアリング１０、１１を介しラックハウジング９により支持されている。その出力シャフト３にピニオン１５が形成され、このピニオン１５に噛み合うラック１６に車輪（図示省略）が連結される。これにより、操舵による入力シャフト２の回転は、トーションバー６を介してピニオン１５に伝達される。そのピニオン１５の回転により、ラック１６は車両幅方向に移動する。このラック１６の移動により車両の操舵がなされる。なお、入出力シャフト２、３とバルブハウジング７との間にはオイルシール４２、４３が介在する。また、ラック１６を支持するサポートヨーク４０が、バネ４１の弾力によりラック１６に押し付けられている。
【００１９】
操舵補助力発生用油圧アクチュエータとして油圧シリンダ２０が設けられている。この油圧シリンダ２０は、ラックハウジング９により構成されるシリンダチューブと、ラック１６に一体化されるピストン２１とを備えている。そのピストン２１により仕切られる油室２２、２３に、操舵方向と操舵抵抗とに応じて圧油を供給するため、ロータリー式油圧制御弁３０が設けられている。
【００２０】
その制御弁３０は、バルブハウジング７に相対回転可能に挿入されている筒状の第１バルブ部材３１と、この第１バルブ部材３１に同軸中心に相対回転可能に挿入されている第２バルブ部材３２とを備えている。その第１バルブ部材３１は出力シャフト３に、ピン２９により同行回転するよう連結されている。その第２バルブ部材３２は、入力シャフト２と一体的に成形されている。すなわち、入力シャフト２の外周部により第２バルブ部材３２が構成され、第２バルブ部材３２は入力シャフト２と同行回転する。よって、第１バルブ部材３１と第２バルブ部材３２とは、操舵抵抗に応じ前記トーションバー６がねじれることで、同軸中心に相対回転する。
【００２１】
そのバルブハウジング７に、ポンプ７０に接続される入口ポート３４と、前記油圧シリンダ２０の一方の油室２２に接続される第１ポート３７と、他方の油室２３に接続される第２ポート３８と、直接にタンク７１に接続される第１出口ポート３６と、後述の可変絞り弁６０を介しタンク７１に接続される第２出口ポート６１とが設けられている。
【００２２】
上記各接続ポート３４、３６、３７、３８、６１は、その第１バルブ部材３１と第２バルブ部材３２との内外周間の弁間流路を介し互いに接続される。すなわち、図３、図４に示すように、第１バルブ部材３１の内周に８ケの凹部５０ａ、５０ｂ、５０ｃが周方向に関し互いに等間隔に形成され、第２バルブ部材３２の外周に８ケの凹部５１ａ、５１ｂ、５１ｃが周方向に関し互いに等間隔に形成されている。図４は実線により第２バルブ部材３２の展開図を示し、鎖線により第１バルブ部材３１に形成された凹部５０ａ、５０ｂ、５０ｃを示す。第１バルブ部材３１に形成された凹部５０ａ、５０ｂ、５０ｃの間に第２バルブ部材３２に形成された凹部５１ａ、５１ｂ、５１ｃが位置する。
【００２３】
その第１バルブ部材３１に形成された凹部は、２ケの右操舵用凹部５０ａと、２ケの左操舵用凹部５０ｂと、４ケの連絡用凹部５０ｃとを構成する。その２ケの右操舵用凹部５０ａは、第１バルブ部材３１に形成された流路５３と前記第１ポート３７とを介し油圧シリンダ２０の右操舵補助力発生用油室２２に接続され、互いに周方向に１８０°離れて配置される。その２ケの左操舵用凹部５０ｂは、第１バルブ部材３１に形成された流路５４と前記第２ポート３８とを介し油圧シリンダ２０の左操舵補助力発生用油室２３に接続され、互いに周方向に１８０°離れて配置される。
【００２４】
その第２バルブ部材３２に形成された凹部は、４ケの圧油供給用凹部５１ａと、２ケの第１圧油排出用凹部５１ｂと、２ケの第２圧油排出用凹部５１ｃとを構成する。その４ケの圧油供給用凹部５１ａは、第１バルブ部材３１に形成された圧油供給路５５と前記入口ポート３４とを介しポンプ７０に接続され、互いに周方向に９０°離れて配置される。その２ケの第１圧油排出用凹部５１ｂは、入力シャフト２に形成された流路５２ａから入力シャフト２とトーションバー６との間を通り、入力シャフト２に形成された流路５２ｂ（図１参照）と第１出口ポート３６とを介しタンク７１に接続され、互いに周方向に１８０°離れて配置される。その２ケの第２圧油排出用凹部５１ｃは、第１バルブ部材３１に形成された流路５９と第２出口ポート６１とを介し可変絞り弁６０に接続され、互いに周方向に１８０°離れて配置されている。なお、第１バルブ部材３１に形成された圧油供給路５５と流路５９は、径方向外方側において周溝状とされている。
【００２５】
各第１圧油排出用凹部５１ｂは右操舵用凹部５０ａと左操舵用凹部５０ｂとの間に配置され、各第２圧油排出用凹部５１ｃは連絡用凹部５０ｃの間に配置され、右操舵用凹部５０ａと連絡用凹部５０ｃとの間および左操舵用凹部５０ｂと連絡用凹部５０ｃとの間に圧油供給用凹部５１ａは配置される。
【００２６】
その第１バルブ部材３１に形成された凹部５０ａ、５０ｂ、５０ｃの軸方向に沿う縁と第２バルブ部材３２に形成された凹部５１ａ、５１ｂ、５１ｃの軸方向に沿う縁との間が絞り部Ａ、Ａ′、Ｂ、Ｂ′、Ｃ、Ｃ′、Ｄ、Ｄ′を構成する。これにより、各絞り部Ａ、Ａ′、Ｂ、Ｂ′、Ｃ、Ｃ′、Ｄ、Ｄ′はポンプ７０とタンク７１と油圧シリンダ２０とを接続する弁間流路２７に配置されている。
【００２７】
図５に示すように、その第２バルブ部材３２に形成された凹部５１ａ、５１ｂ、５１ｃの軸方向に沿う縁は面取り部とされている。その連絡用凹部５０ｃと第２圧油排出用凹部５１ｃとの間の絞り部Ｂ′、Ｄ′における第２圧油排出用凹部５１ｃの軸方向に沿う縁（図３において△で囲む）の面取り部の幅をＷ、圧油供給用凹部５１ａと連絡用凹部５０ｃとの間の絞り部Ａ′、Ｃ′における圧油供給用凹部５１ａの軸方向に沿う縁（図３において□で囲む）の面取り部の幅をＷ′、その他の第２バルブ部材３２に形成された凹部の軸方向に沿う縁（図３において○で囲む）の面取り部の幅をＷ″として、図４、図５に示すように、Ｗ＞Ｗ′＞Ｗ″とされている。操舵抵抗のない状態（図４、図５の状態）にある各絞り部Ａ、Ａ′、Ｂ、Ｂ′、Ｃ、Ｃ′、Ｄ、Ｄ′を全閉するのに要する両バルブ部材３１、３２の相対回転角度（以下、「閉鎖角度」という）を互いに比較すると、連絡用凹部５０ｃと第２圧油排出用凹部５１ｃとの間の絞り部Ｂ′、Ｄ′の閉鎖角度θｒは、圧油供給用凹部５１ａと連絡用凹部５０ｃとの間の絞り部Ａ′、Ｃ′の閉鎖角度θｓよりも大きく、両閉鎖角度θｒ、θｓは、他の各絞り部Ａ、Ｂ、Ｃ、Ｄの閉鎖角度θｔよりも大きい。これにより、第１バルブ部材３１と第２バルブ部材３２との間の各絞り部は、複数の絞り部Ａ、Ｂ、Ｃ、Ｄからなる第１の組と、第１の組に属する各絞り部Ａ、Ｂ、Ｃ、Ｄよりも閉鎖角度の大きな複数の絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′からなる第２の組とに組分けされる。また、第２の組に属する絞り部は、圧油供給用凹部５１ａと連絡用凹部５０ｃとの間の絞り部Ａ′、Ｃ′と、この絞り部Ａ′、Ｃ′よりも閉鎖角度の大きな連絡用凹部５０ｃと第２圧油排出用凹部５１ｃとの間の絞り部Ｂ′、Ｄ′の２種類とされる。
【００２８】
その入力シャフト２と出力シャフト３は、路面から車輪を介し伝達される抵抗によるトーションバー６のねじれによって相対回転する。その相対回転により第１バルブ部材３１と第２バルブ部材３２とが相対回転することで、各絞り部Ａ、Ｂ、Ｃ、Ｄ、Ａ′、Ｂ′、Ｃ′、Ｄ′の開度が変化し、油圧シリンダ２０が操舵方向と操舵抵抗に応じた操舵補助力を発生する。第１の組に属する絞り部Ａ、Ｂ、Ｃ、Ｄは、第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′よりも、閉鎖角度が小さいので、その操舵抵抗の変化に対する油圧変化割合は大きくなる。
【００２９】
図４は操舵が行なわれていない状態を示す。この状態では両バルブ部材３１、３２の間の絞り部Ａ、Ｂ、Ｃ、Ｄ、Ａ′、Ｂ′、Ｃ′、Ｄ′は全て開かれ、入口ポート３４と各出口ポート３６、６１とは弁間流路２７を介し連通するので、ポンプ７０から制御弁３０に流入する油はタンク７１に還流し、操舵補助力は発生しない。
【００３０】
この状態から右方へ操舵することによって生じる操舵抵抗により両バルブ部材３１、３２が相対回転すると、図３に示すように、圧油供給用凹部５１ａと右操舵用凹部５０ａとの間の絞り部Ａおよび左操舵用凹部５０ｂに隣接する圧油供給用凹部５１ａと連絡用凹部５０ｃとの間の絞り部Ａ′の開度が大きくなり、右操舵用凹部５０ａと第１圧油排出用凹部５１ｂとの間の絞り部Ｂおよび左操舵用凹部５０ｂに隣接する圧油供給用凹部５１ａに隣接する連絡用凹部５０ｃと第２圧油排出用凹部５１ｃとの間の絞り部Ｂ′の開度が小さくなり、圧油供給用凹部５１ａと左操舵用凹部５０ｂとの間の絞り部Ｃおよび右操舵用凹部５０ａに隣接する圧油供給用凹部５１ａと連絡用凹部５０ｃとの間の絞り部Ｃ′の開度が小さくなり、左操舵用凹部５０ｂと第１圧油排出用凹部５１ｂとの間の絞り部Ｄおよび右操舵用凹部５０ａに隣接する圧油供給用凹部５１ａに隣接する連絡用凹部５０ｃと第２圧油排出用凹部５１ｃとの間の絞り部Ｄ′の開度が大きくなる。これにより、図中矢印で示す圧油の流れにより油圧シリンダ２０の右操舵補助力発生用油室２２に操舵方向と操舵抵抗に応じた圧力の圧油が供給され、また、左操舵補助力発生用油室２３からタンク７１に油が還流し、車両の右方への操舵補助力が油圧シリンダ２０からラック１６に作用する。
【００３１】
左方へ操舵すると、第１バルブ部材３１と第２バルブ部材３２とは、右方に操舵した場合と逆方向に相対回転し、絞り部Ａ、Ａ′の開度が小さくなり、絞り部Ｂ、Ｂ′の開度が大きくなり、絞り部Ｃ、Ｃ′の開度が大きくなり、絞り部Ｄ、Ｄ′の開度が小さくなる。よって、車両の左方への操舵補助力が油圧シリンダ２０からラック１６に作用する。
【００３２】
図１、図８に示すように、上記第２出口ポート６１に連通する可変絞り弁６０は、バルブハウジング７に着脱可能な第２バルブハウジング７′と、この第２バルブハウジング７′に形成された挿入孔６６に軸中心に回転可能に挿入される円柱状スプール６２とを備える。
【００３３】
その挿入孔６６の一端にプラグ６８がシールリング６９を介してねじ合わされる。そのプラグ６８には工具挿入用六角孔６８ａが形成され、その外周にロックナット７９がねじ合わされる。その挿入孔６６の他端はカバー９０により閉鎖されている。そのカバー９０にステッピングモータ８０が取り付けられられ、そのステッピングモータ８０の出力軸８０ａにスプール６２の一端が連結されている。そのステッピングモータ８０にコントローラ（図示省略）が接続される。そのコントローラは車速センサ（図示省略）に接続され、そのステッピングモータ８０を車速に応じ制御する。これにより、スプール６２は、車速零の状態で待機位置に位置するものとされ、高速になる程に待機位置から一方向への回転角度が大きくなるように回転駆動される。なお、ステッピングモータ８０として減速機構を内蔵するものを用いたり、ステッピングモータ８０とスプール６２との間に減速機構を介在させてもよい。
【００３４】
図８、図９に示すように、そのスプール６２の内部に圧油室６２ａが形成される。この圧油室６２ａは、スプール６２の一端側と多端側とにおいて閉鎖される。そのスプール６２の外周に、その圧油室６２ａに通じる開口６２ｂが、そのスプール６２の周方向に等間隔をおいた４位置に形成されている。
【００３５】
その挿入孔６６の内周に、そのスプール６２の外周に対向する圧油排出用の凹部６６ａが、そのスプール６２の周方向に等間隔をおいた４位置に形成されている。
【００３６】
その開口６２ｂにおけるスプール６２の軸方向に沿う一縁と、圧油排出用凹部６６ａにおけるスプール６２の軸方向に沿う一縁との間が、スプール６２の回転によって開度が変化する絞り部６７とされている。なお、その絞り部６７を構成する各開口６２ｂの一縁は、スプール６２の軸方向に沿った面取り部６２ｃとされている。上記のように、そのスプール６２は車両の運転条件である車速に応じて回転駆動されることから、その絞り部６７の開度は車速に応じて変化する。本実施形態では、その絞り部６７の開度は、高速になってスプール６２が図９において矢印Ｐ方向に回転すると大きくなり、低速になってスプール６２が矢印Ｑ方向に回転すると小さくなる。図９に示す状態は、絞り部６７の開度が最小の状態を示し、本実施形態ではスプール６２の外周と挿入孔６６の内周との間の隙間に対応する開度とされ、実質的に流路面積は零とされる。
【００３７】
その４つの開口６２ｂの中の一つに通じる圧油導入路５８が第２バルブハウジング７′に形成されている。その圧油導入路５８は、上記第２出口ポート６１に接続される。
【００３８】
図８、図１０に示すように、各圧油排出用凹部６６ａに通じると共にスプール６２の外周に対向する周溝６６ｂが、挿入孔６６の内周に形成されている。その周溝６６を介して各圧油排出用凹部６６ａに通じる圧油排出路７６が、バルブハウジング７と第２バルブハウジング７′に亘り形成されている。その圧油排出路７６は上記第１出口ポート３６に通じる。
これにより、ポンプ７０から供給される圧油は、上記制御弁３０の第２出口ポート６１から圧油導入路５８を介して開口６２ｂに至り、この開口６２ｂから圧油室６２ａを介して絞り部６７に至り、この絞り部６７から圧油排出用凹部６６ａ、周溝６６ｂ、圧油排出路７６および第１出口ポート３６を介してタンク７１に至る。
【００３９】
図８に示すように、そのスプール６２は、軸方向に離れた２位置においてボールベアリング９１、９２により支持されている。なお、ボールベアリング９１、９２以外の転がり軸受や、ブッシュのような滑り軸受を用いて支持してもよい。一方のボールベアリング９１の内輪９１ａはスプール６２の外周に嵌め合わされ、外輪９１ｂは挿入孔６６の内周の段差６６ｃと止め輪９３とにより軸方向移動が阻止されている。他方のボールベアリング９２の内輪９２ａはスプール６２の外周の小径部６２ｄに嵌め合わされ、外輪９２ｂは挿入孔６６にシールリング９５を介して嵌め合わされた環状ブロック９４に嵌め合わされている。その環状ブロック９４とモータ８０の出力軸８０ａとの間にオイルシール９６が設けられている。
【００４０】
前記プラグ６８は基準位置設定部材を兼用する。すなわち、図１１の（１）、（２）に示すように、そのプラグ６８の一端に形成された突出部６８ｂに、一対の互いに平行な平坦な受け面６８ｃ、６８ｄが、挿入孔６６の軸方向に平行に形成されている。
また、図１２の（１）、（２）に示すように、スプール６２の一端に、そのプラグ６８の突出部６８ｂが挿入される二股部６２ｄが形成されている。その二股部６２ｄの一方の内面は、挿入孔６６の軸方向に平行な第１、第２平坦面６２ｅ、６２ｆから構成され、その二股部６２ｄの他方の内面は、第１平坦面６２ｅに平行な第３平坦面６２ｇと第２平坦面６２ｆに平行な第４平坦面６２ｈとから構成される。
その第１平坦面６２ｅと第３平坦面６２ｇとの距離（ａ＋α）および第２平坦面６２ｆと第４平坦面６２ｈとの距離（ａ＋α）は、互いに等しく、両受け面６８ｃ、６８ｄの間隔ａよりも大きくされる。
その第１平坦面６２ｅと第４平坦面６２ｈとのなす各θおよび第２平坦面６２ｆと第３平坦面６２ｇとのなす各θは、互いに等しく、突出部６８ｂに対するスプール６２の相対回転を所定角度だけ許容するように定められる。その突出部６８ｂに対するスプール６２の相対回転角度は、その相対回転により上記絞り部６７の開度を少なくとも必要とされる最小開度から最大開度の範囲で変化させることができるように定められる。
そのプラグ６８の両受け面６８ｃ、６８ｄの一方と、第１〜第４平坦面６２ｅ、６２ｆ、６２ｇ、６２ｈの中の一つとの接触位置を基準位置として、そのスプール６２の回転角度に応じて上記絞り部６７の開度が制御される。そのプラグ６８の第２バルブハウジング７′に対するねじ込み量を変化させることで、その基準位置は変更可能とされている。
【００４１】
その絞り部６７の開度の変化により、上記油圧シリンダ２０に作用する油圧が制御される。すなわち、その絞り部６７の開度の最大値は、第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′の合計開度の最大値（両バルブ部材３１、３２の相対回転角が大きくなる程に開度が小さくなる特性における最大値である。すなわち、右操舵時は絞り部Ｂ′、Ｃ′の合計開度の最大値をいい、左操舵時は絞り部Ａ′、Ｄ′の合計開度の最大値をいう。以下「合計開度の最大値」という場合は同旨）以上、若しくは絞り機能を奏さなくなるまで大きくされている。その絞り部６７の開度の最小値は、第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′の合計開度の最小値（両バルブ部材３１、３２の相対回転角が大きくなる程に開度が小さくなる特性における最小値である。すなわち、右操舵時は絞り部Ｂ′、Ｃ′の合計開度の最小値をいい、左操舵時は絞り部Ａ′、Ｄ′の合計開度の最小値をいい、全閉状態を含む。以下「合計開度の最小値」という場合は同旨）以下とされる。
【００４２】
これにより、図２に示す油圧回路が構成され、第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′とタンク７１との間の油路の開度が、車速に応じた可変絞り弁６０の作動により変化する。すなわち、第１の組に属する絞り部Ａ、Ｂ、Ｃ、Ｄにより制御される圧油流量の、第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′により制御される圧油流量に対する割合が、可変絞り弁６０の作動により変化する。
【００４３】
図７において、実線Ｘは、両バルブ部材３１、３２の相対回転角に対する第１の組に属する絞り部Ａ、Ｂ、Ｃ、Ｄの開度の変化特性を示す。１点鎖線Ｕは、その相対回転角に対する第２の組に属する連絡用凹部５０ｃと第２圧油排出用凹部５１ｃとの間の絞り部Ｂ′、Ｄ′の開度の変化特性を示す。１点鎖線Ｖは、その相対回転角に対する第２の組に属する圧油供給用凹部５１ａと連絡用凹部５０ｃとの間の絞り部Ａ′、Ｃ′の開度の変化特性を示す。実線Ｙは、その相対回転角に対する第２の組に属する全ての絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′の開度の合成した変化特性を示す。なお、図７における各開度の変化特性は、その相対回転角が大きくなる程に小さくなることから明らかなように、右操舵時は絞り部Ｂ、Ｂ′、Ｃ、Ｃ′の変化特性を示し、左操舵時は絞り部Ａ、Ａ′、Ｄ、Ｄ′の変化特性を示している。破線Ｒは、可変絞り弁６０により設定される可変絞り弁自身の絞り部６７の中速走行時における開度を示す。なお、図７において開度は流路面積として示す。
【００４４】
低速走行時においては、スプール６２の回転により可変絞り弁６０の絞り部６７の開度が最小になる。よって、油圧シリンダ２０に作用する油圧は、第１の組の絞り部Ａ、Ｂ、Ｃ、Ｄの開度の変化特性線Ｘに応じ制御される。この場合、図６において一点鎖線で示すように、操舵入力トルクが小さく、両バルブ部材３１、３２の相対回転角が小さくても、第１の組に属する絞り部Ａ、Ｂ、Ｃ、Ｄの開度を小さくし、操舵補助力を発生させる油圧の増加割合を大きくし、低速走行時における操舵の高応答性を満足させることができる。
【００４５】
高速走行時においては、スプール６２の回転により可変絞り弁６０の絞り部６７の開度は、第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′の合計開度の最大値以上になる。よって、油圧シリンダ２０に作用する油圧は、第２の組の絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′の開度の変化特性線Ｙ及び第１の組の絞り部Ａ、Ｂ、Ｃ、Ｄの開度の変化特性線Ｘの合成特性に応じ制御される。この場合、図６において実線で示すように、操舵入力トルクを大きくし、両バルブ部材３１、３２の相対回転角を大きくしない限り、第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′の開度は小さくなることなく大きく保持され、操舵補助力を発生させる油圧の増加割合は小さいので、高速走行時における操舵の安定性を満足させることができる。
【００４６】
中速走行時においては、スプール６２の変位により可変絞り弁６０の絞り部６７の開度は、第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′の合計開度の最小値よりも大きく最大値よりも小さくなる。これにより、図７に示すように、第１の組に属する絞り部Ａ、Ｂ、Ｃ、Ｄの合計開度が最小値になるまでの間（図７において両バルブ部材の相対回転角がθａになるまでの間）は、その第１の組に属する絞り部Ａ、Ｂ、Ｃ、Ｄの合計開度の変化特性線Ｘに絞り部６７の開度の特性線Ｒを合成した特性に応じた操舵補助力が付与される。第１の組に属する絞り部Ａ、Ｂ、Ｃ、Ｄが全閉状態になった時点から、第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′の合計開度が可変絞り弁６０の絞り部６７の開度よりも小さくなるまでの間（図７において両バルブ部材の相対回転角がθａとθｂとの間）では、操舵補助力は絞り部６７の開度により定まる一定値になる。しかる後に、第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′の合計開度が可変絞り弁６０の絞り部６７の開度よりも小さくなると、第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′の合計開度の変化特性線Ｙに応じた操舵補助力が付与される。
【００４７】
その第１の組に属する絞り部Ａ、Ｂ、Ｃ、Ｄが全閉状態になった後に、第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′の合計開度が可変絞り弁６０の絞り部６７の開度よりも小さくなるまでの間（θａ〜θｂの間）は、その第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′が全閉状態になる点と、第１の組に属する絞り部Ａ、Ｂ、Ｃ、Ｄが全閉状態になる点との差（θｃ−θａ）を小さくすることなく、小さくされている。すなわち、仮に、第２の組に属する圧油供給用凹部５１ａと連絡用凹部５０ｃとの間の絞り部Ａ′、Ｃ′が、連絡用凹部５０ｃと第２圧油排出用凹部５１ｃとの間の絞り部Ｂ′、Ｄ′と同様に図中１点鎖線Ｕで示す相対回転角に対する開度変化特性を有すると仮定すると、相対回転角に対する第２の組に属する全ての絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′の合計開度の合成変化特性は、図７において２点鎖線Ｍで示すものになる。そうすると、第２の組に属する絞り部Ａ′、Ｂ′、Ｃ′、Ｄ′の開度が、可変絞り弁６０の自身の絞り部６７の開度よりも小さくなるまでの間（両バルブ部材の相対回転角がθａとθｄとの間）は大きくなるので、図６において２点鎖線で示すように、操舵補助力を操舵抵抗に応じ制御できない領域Ｌが大きくなる。これに対し、上記実施形態では、第２の組に属する圧油供給用凹部５１ａと連絡用凹部５０ｃとの間の絞り部Ａ′、Ｃ′の閉鎖角度θｓは、連絡用凹部５０ｃと第２圧油排出用凹部５１ｃとの間の絞り部Ｂ′、Ｄ′の閉鎖角度θｒよりも小さいので、中速走行時において操舵補助力を操舵抵抗に応じ制御できない領域を小さくできる。しかも、圧油供給用凹部５１ａと連絡用凹部５０ｃとの間の絞り部Ａ′、Ｃ′が全閉状態になる点（図７において両バルブ部材の相対回転角がθｅの点）では、連絡用凹部５０ｃと第２圧油排出用凹部５１ｃとの間の絞り部Ｂ′、Ｄ′は未だ閉じていないので、操舵補助力を操舵抵抗に応じ制御できる領域は小さくなることはない。
【００４８】
上記構成の可変絞り弁６０によれば、スプール６２を回転させることで絞り部６７の開度を変化させるので、モータ８０の出力軸８０ａの回転運動を直線運動に変換するためのネジ部材やスプール６２のネジ加工を必要としない。そのスプール６２は軸方向に離れた２位置においてボールベアリング９１、９２より支持されるので、振れ回りが抑制される。これにより、スプール６２の外周が挿入孔６６の内周に押し付けられることにより発生する摩擦を抑制し、スプール６２の作動不良やロックを防止できる。
また、そのスプール６２の両端間において圧油導入路５８と圧油排出路７６とを介して圧油の導入と排出とを行えるので、可変絞り弁６０の軸方向寸法を小さくすることができる。また、絞り部６７の数に対して必要とされる開口６２ｂと圧油排出用凹部６６ａの数を可及的に少なくできるので、可変絞り弁６０の周方向寸法を小さくでき、しかも、絞り部６７の数を多くすることで、各絞り部６７における圧油流量を少なくし、キャビテーション気泡発生に起因する流動音を低減できる。
さらに、プラグ６８とスプール６２との接触位置を基準として絞り部６７の開度制御を行うことができ、その基準位置は、プラグ６８の第２バルブハウジング７′に対するねじ込み量を変化させることで調節できる。これにより、その絞り部６７の開度を精密に制御できる。
これにより、車速等の運転条件に応じてスプール６２を回転させ、絞り部６７の開度を変化させることで、操舵補助力発生用油圧シリンダ２０に作用する油圧を制御し、所望の操舵特性を得ることができる油圧パワーステアリング装置１を構成できる。
【００４９】
なお、本発明は上記実施形態に限定されない。例えば、上記実施形態ではスプールを車速に応じて回転させたが、舵角等の他の運転条件に応じて回転させてもよい。本発明の可変絞り弁を油圧パワーステアリング装置以外の油圧機器の油圧回路において使用してもよい。
【００５０】
【発明の効果】
本発明によれば、動作が確実で、コンパクトで、圧油の流動に伴う音の発生を低減でき、絞り部の開度を精密に制御でき、油圧パワーステアリング装置の制御に適した可変絞り弁を提供できる。
【図面の簡単な説明】
【図１】本発明の実施形態の油圧パワーステアリング装置の縦断面図
【図２】本発明の実施形態の油圧パワーステアリング装置の油圧回路を示す図
【図３】本発明の実施形態の油圧パワーステアリング装置における制御弁の横断面構造の説明図
【図４】本発明の実施形態の油圧パワーステアリング装置における制御弁の展開図
【図５】本発明の実施形態の油圧パワーステアリング装置の制御弁の要部の拡大図
【図６】本発明の実施形態の油圧パワーステアリング装置における入力トルクと油圧との関係及び両バルブ部材の相対回転角と油圧との関係を示す図
【図７】本発明の実施形態の油圧パワーステアリング装置における制御弁の絞り部の開度とバルブ部材の相対回転角との関係を示す図
【図８】本発明の実施形態の油圧パワーステアリング装置の可変絞り弁の縦断面図
【図９】図８のＩＸ‐ＩＸ線断面図
【図１０】図８のＸ‐Ｘ線断面図
【図１１】本発明の実施形態のプラグの（１）は断面図、（２）は底面図
【図１２】本発明の実施形態のスプールの（１）は平面図、（２）は部分側面図
【符号の説明】
１油圧パワーステアリング装置
７′ 第２バルブハウジング
２０油圧シリンダ
５８圧油導入路
６０可変絞り弁
６２スプール
６２ａ圧油室
６２ｂ開口
６６挿入孔
６６ａ圧油排出用凹部
６７絞り部
６８プラグ（基準位置設定部材）
７６圧油排出路
８０モータ
９１、９２ボールベアリング[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable throttle valve including a throttle portion whose opening degree changes with axial displacement of a spool.
[0002]
[Prior art and problems to be solved by the invention]
In a hydraulic power steering device, a variable throttle valve having a throttle portion whose opening degree changes according to driving conditions such as a vehicle speed is used, and the hydraulic pressure acting on the steering assist force generating hydraulic actuator is controlled according to the driving conditions. Yes.
[0003]
For example, a variable throttle valve having a throttle portion that is driven by a motor to rotate a screw member that is screwed into a spool that is inserted into the housing so as to be axially movable, and whose opening is changed by the axial movement of the spool by the rotation of the screw member Is used.
[0004]
In order to precisely control the opening of the throttle portion, it is necessary to prevent relative rotation of the spool with respect to the housing. In order to prevent the relative rotation, an anti-rotation member is provided, a portion in contact with the spool and the housing so as not to rotate relative to each other is formed, and the shaft center of the spool and the shaft center of the screw member are eccentric. It has been broken.
[0005]
However, if a rotation preventing member is provided to prevent the relative rotation, or if a portion in contact with the spool and the housing is formed, the cost, processing, and assembly man-hour are increased. When the shaft center of the spool and the shaft center of the screw member are decentered, a force is applied to press the outer periphery of the spool against the inner periphery of the insertion hole by the rotation of the screw member. There is a problem that the displacement of the spool is hindered by friction based on the pressing force.
[0006]
Further, there is used a variable throttle valve that can change the opening degree of the throttle portion between the inner periphery of the insertion hole and the outer periphery of the spool by rotation of the spool in the insertion hole formed in the housing. When such a rotating spool is used, screw processing of a screw member or a spool becomes unnecessary.
[0007]
However, the conventional rotating spool is supported at one point by the rotating shaft of the motor, or is supported by the inner surface of the insertion hole via a seal ring. Such a spool supported at one point easily swings, and there is a problem that rotation is hindered by friction with the inner surface of the insertion hole. In addition, the spool supported by the inner surface of the insertion hole via the seal ring is hindered from rotating by the tightening force of the seal ring, or the seal ring is deformed and swung to cause friction with the inner surface of the insertion hole. There is a problem that rotation is inhibited.
[0008]
When a rotary spool having a through hole is used, a recess for introducing pressure oil is formed on the inner periphery of the insertion hole, and a recess for discharging pressure oil is formed on the outer periphery of the spool. And the through hole are communicated via a through hole, and a narrowed portion is formed between the pressure oil introduction recess and the pressure oil discharge recess. In this case, since the pressure oil is guided from the through hole to the outside in the axial direction of the spool, it is necessary to form a discharge passage for the pressure oil outside in the axial direction of the spool. Therefore, there exists a problem that the axial direction dimension of a variable throttle valve becomes large.
[0009]
When a solid spool is used as the rotary spool, a pressure oil introduction recess and a pressure oil discharge recess are formed on the inner periphery of the insertion hole, and the pressure oil introduction recess and the pressure oil discharge recess are formed. A recess is formed in the outer periphery of the spool in the middle, and a portion between the pressure oil introduction recess and the pressure oil discharge recess is used as a throttle portion. In this case, the number of recesses formed in the inner circumference of the insertion hole and the outer circumference of the spool is increased with respect to the number of throttle parts, and there is a problem that the circumferential dimension of the variable throttle valve is increased. . Further, if the number of throttle parts is reduced in order to reduce the circumferential dimension, there is a problem that the flow rate of pressure oil at each throttle part increases and the flow noise caused by the generation of cavitation bubbles increases.
[0010]
When the rotary spool is used, it is necessary to precisely set the reference position of the spool in order to precisely control the opening degree of the throttle portion. However, in the conventional variable throttle valve in which the opening degree of the throttle portion can be changed by the rotation of the spool, no means for adjusting the reference position of the spool is disclosed.
[0011]
An object of this invention is to provide the variable throttle valve which can solve the said problem.
[0012]
[Means for Solving the Problems]
The variable throttle valve according to the present invention includes a housing, a spool that is rotatably inserted into an insertion hole formed in the housing, a motor that rotates the spool, and a degree of opening that varies depending on the rotation of the spool. And a bearing that supports the spool at two positions separated in the axial direction.
According to the configuration of the present invention, since the opening degree of the throttle portion is changed by rotating the spool, a screw member for converting the rotational motion of the output shaft of the motor into a linear motion and screw processing of the spool are not required. . Since the spool is supported by the bearing at two positions separated in the axial direction, swinging is suppressed. Thereby, the friction which generate | occur | produces when the outer periphery of a spool is pressed on the inner periphery of an insertion hole can be suppressed, and the malfunction of a spool and a lock | rock can be prevented.
[0013]
A pressure oil chamber is formed inside the spool, an opening leading to the pressure oil chamber is formed on the outer periphery of the spool, and a pressure oil discharge recess facing the outer periphery of the spool is formed on the inner periphery of the insertion hole. Is formed between the recess for pressure oil discharge and the opening, and the throttle portion, the pressure oil introduction path leading to the opening in the housing, and the pressure oil discharge path leading to the pressure oil discharge recess Is preferably formed.
According to this configuration, since the pressure oil can be introduced and discharged between both ends of the spool, the axial dimension of the variable throttle valve can be reduced.
[0014]
The opening on the outer periphery of the spool and the pressure oil discharging recesses on the inner periphery of the insertion hole are preferably formed at a plurality of positions spaced in the circumferential direction of the spool.
According to this configuration, the number of openings required for the number of throttle parts and the number of pressure oil discharge recesses can be reduced as much as possible, so that the circumferential dimension of the variable throttle valve can be reduced, and the throttle parts By increasing the number, the flow rate of pressure oil in each throttle part can be reduced, and the flow noise caused by the generation of cavitation bubbles can be reduced.
[0015]
A reference position setting member screwed to the housing is provided, and the contact position between the reference position setting member and the spool is used as a reference position, and the opening of the throttle portion can be controlled according to the rotation angle of the spool. It is preferable that the reference position can be changed by changing the screwing amount of the reference position setting member with respect to the housing.
According to this configuration, the opening degree control of the throttle portion can be performed with reference to the contact position between the reference position setting member and the spool. The reference position can be adjusted by changing the screwing amount of the reference position setting member with respect to the housing. Thereby, the opening degree of the throttle part can be controlled precisely.
[0016]
The opening of the throttle can be changed according to the driving conditions of the vehicle, and the hydraulic pressure acting on the hydraulic actuator for generating the steering assist force of the hydraulic power steering device of the vehicle can be controlled by changing the opening of the throttle Is preferred.
As a result, by rotating the spool according to the driving conditions such as the vehicle speed and changing the opening of the throttle portion, the hydraulic pressure acting on the hydraulic actuator for generating the steering assist force can be controlled and desired steering characteristics can be obtained. A hydraulic power steering device can be configured.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
A rack and pinion type hydraulic power steering apparatus 1 shown in FIG. 1 includes an input shaft 2 connected to a steering wheel (not shown) and an output shaft 3 connected to the input shaft 2 via a torsion bar 6. . The torsion bar 6 is connected to the input shaft 2 by a pin 4 and connected to the output shaft 3 by a serration 5. The input shaft 2 is supported by the valve housing 7 via a bearing 8 and is supported by the output shaft 3 via a bush 12. The output shaft 3 is supported by the rack housing 9 via bearings 10 and 11. A pinion 15 is formed on the output shaft 3, and wheels (not shown) are connected to a rack 16 that meshes with the pinion 15. Thereby, the rotation of the input shaft 2 by steering is transmitted to the pinion 15 via the torsion bar 6. The rack 16 moves in the vehicle width direction by the rotation of the pinion 15. The vehicle is steered by the movement of the rack 16. Oil seals 42 and 43 are interposed between the input / output shafts 2 and 3 and the valve housing 7. A support yoke 40 that supports the rack 16 is pressed against the rack 16 by the elasticity of the spring 41.
[0019]
A hydraulic cylinder 20 is provided as a steering assist force generating hydraulic actuator. The hydraulic cylinder 20 includes a cylinder tube constituted by the rack housing 9 and a piston 21 integrated with the rack 16. In order to supply pressure oil to the oil chambers 22 and 23 partitioned by the piston 21 according to the steering direction and the steering resistance, a rotary hydraulic control valve 30 is provided.
[0020]
The control valve 30 includes a cylindrical first valve member 31 inserted into the valve housing 7 so as to be relatively rotatable, and a second valve member inserted into the first valve member 31 so as to be relatively rotatable about a coaxial center. 32. The first valve member 31 is connected to the output shaft 3 so as to rotate together with the pin 29. The second valve member 32 is formed integrally with the input shaft 2. That is, the second valve member 32 is configured by the outer peripheral portion of the input shaft 2, and the second valve member 32 rotates along with the input shaft 2. Therefore, the first valve member 31 and the second valve member 32 rotate relative to each other about the coaxial center by twisting the torsion bar 6 according to the steering resistance.
[0021]
The valve housing 7 has an inlet port 34 connected to the pump 70, a first port 37 connected to one oil chamber 22 of the hydraulic cylinder 20, and a second port 38 connected to the other oil chamber 23. And a first outlet port 36 directly connected to the tank 71 and a second outlet port 61 connected to the tank 71 via a variable throttle valve 60 described later.
[0022]
The connection ports 34, 36, 37, 38, 61 are connected to each other via an inter-valve flow path between the inner and outer periphery of the first valve member 31 and the second valve member 32. That is, as shown in FIGS. 3 and 4, eight recesses 50 a, 50 b, 50 c are formed at equal intervals in the circumferential direction on the inner periphery of the first valve member 31, and 8 recesses are formed on the outer periphery of the second valve member 32. The concave portions 51a, 51b and 51c are formed at equal intervals in the circumferential direction. FIG. 4 shows a developed view of the second valve member 32 by a solid line, and shows the recesses 50a, 50b, 50c formed in the first valve member 31 by a chain line. The recesses 51a, 51b, 51c formed in the second valve member 32 are located between the recesses 50a, 50b, 50c formed in the first valve member 31.
[0023]
The recesses formed in the first valve member 31 constitute two right steering recesses 50a, two left steering recesses 50b, and four communication recesses 50c. The two right steering recesses 50a are connected to the right steering assist force generating oil chamber 22 of the hydraulic cylinder 20 through the flow path 53 formed in the first valve member 31 and the first port 37, and are mutually connected. They are arranged 180 ° apart in the circumferential direction. The two left steering recesses 50b are connected to the left steering assist force generating oil chamber 23 of the hydraulic cylinder 20 through the flow path 54 formed in the first valve member 31 and the second port 38, and are mutually connected. They are arranged 180 ° apart in the circumferential direction.
[0024]
The recesses formed in the second valve member 32 include four pressure oil supply recesses 51a, two first pressure oil discharge recesses 51b, and two second pressure oil discharge recesses 51c. Constitute. The four pressure oil supply recesses 51a are connected to the pump 70 via the pressure oil supply passage 55 formed in the first valve member 31 and the inlet port 34, and are disposed 90 ° apart from each other in the circumferential direction. The The two first pressure oil discharge recesses 51b pass between the input shaft 2 and the torsion bar 6 from the flow path 52a formed in the input shaft 2, and the flow path 52b formed in the input shaft 2 (FIG. 1) and the first outlet port 36, and is connected to the tank 71 and arranged 180 degrees apart from each other in the circumferential direction. The two second pressure oil discharge recesses 51c are connected to the variable throttle valve 60 via the flow path 59 formed in the first valve member 31 and the second outlet port 61, and are 180 ° apart from each other in the circumferential direction. Are arranged. The pressure oil supply path 55 and the flow path 59 formed in the first valve member 31 have a circumferential groove shape on the radially outer side.
[0025]
Each first pressure oil discharge recess 51b is disposed between the right steering recess 50a and the left steering recess 50b, and each second pressure oil discharge recess 51c is disposed between the communication recesses 50c. The pressure oil supply recess 51a is disposed between the recess 50a and the communication recess 50c and between the left steering recess 50b and the communication recess 50c.
[0026]
A constriction is defined between the edges along the axial direction of the recesses 50a, 50b and 50c formed in the first valve member 31 and the edges along the axial direction of the recesses 51a, 51b and 51c formed in the second valve member 32. A, A ′, B, B ′, C, C ′, D, D ′ are formed. Accordingly, the throttle portions A, A ′, B, B ′, C, C ′, D, and D ′ are arranged in the inter-valve flow path 27 that connects the pump 70, the tank 71, and the hydraulic cylinder 20.
[0027]
As shown in FIG. 5, the edges along the axial direction of the recesses 51a, 51b, 51c formed in the second valve member 32 are chamfered portions. Chamfering of an edge (enclosed by Δ in FIG. 3) along the axial direction of the second pressure oil discharge recess 51c at the throttle portions B ′ and D ′ between the communication recess 50c and the second pressure oil discharge recess 51c. The width of the portion is W, and the edge (enclosed by □ in FIG. 3) along the axial direction of the pressure oil supply recess 51a in the throttle portions A ′ and C ′ between the pressure oil supply recess 51a and the communication recess 50c. 4 and 5, where the width of the chamfered portion is W ′, and the width of the chamfered portion of the edge (encircled in FIG. 3) along the axial direction of the other concave portion formed in the second valve member 32 is W ″. As shown, W> W ′> W ″. Both valve members 31 required to fully close the throttle portions A, A ′, B, B ′, C, C ′, D, D ′ in a state without steering resistance (the state of FIGS. 4 and 5), 32 relative to each other (hereinafter referred to as “closing angle”), the closing angle θr of the throttle portions B ′ and D ′ between the communication recess 50c and the second pressure oil discharge recess 51c is equal to the pressure The closing angles θs of the throttles A ′ and C ′ between the oil supply recess 51a and the communication recess 50c are larger than the closing angles θr and θs of the other throttles A, B, C, and D. It is larger than the closing angle θt. Thereby, each throttle part between the 1st valve member 31 and the 2nd valve member 32 is each 1st group which consists of a plurality of throttle parts A, B, C, and D, and each throttle which belongs to the 1st group. They are grouped into a second group consisting of a plurality of throttle parts A ′, B ′, C ′, D ′ having a larger closing angle than the parts A, B, C, D. In addition, the throttle portions belonging to the second group have throttle portions A ′ and C ′ between the pressure oil supply concave portion 51a and the communication concave portion 50c, and a closing angle larger than the throttle portions A ′ and C ′. There are two types of throttle portions B ′ and D ′ between the communication recess 50c and the second pressure oil discharge recess 51c.
[0028]
The input shaft 2 and the output shaft 3 are rotated relative to each other by the torsion of the torsion bar 6 due to the resistance transmitted from the road surface via the wheels. Due to the relative rotation, the first valve member 31 and the second valve member 32 rotate relative to each other, so that the opening degree of each of the throttle portions A, B, C, D, A ′, B ′, C ′, and D ′ changes. Then, the hydraulic cylinder 20 generates a steering assist force according to the steering direction and the steering resistance. The throttle portions A, B, C, and D belonging to the first group have smaller closing angles than the throttle portions A ′, B ′, C ′, and D ′ belonging to the second group, so that the steering resistance changes. The rate of change in hydraulic pressure with respect to increases.
[0029]
FIG. 4 shows a state where steering is not performed. In this state, the throttle portions A, B, C, D, A ′, B ′, C ′, and D ′ between the valve members 31 and 32 are all opened, and the inlet port 34 and the outlet ports 36 and 61 are Since the communication is made via the inter-valve flow path 27, the oil flowing from the pump 70 to the control valve 30 returns to the tank 71, and no steering assist force is generated.
[0030]
When the two valve members 31 and 32 are rotated relative to each other by steering resistance generated by steering to the right from this state, as shown in FIG. 3, the throttle portion between the pressure oil supply recess 51a and the right steering recess 50a. The opening of the throttle portion A ′ between the pressure oil supply recess 51a adjacent to the A and left steering recess 50b and the communication recess 50c increases, and the right steering recess 50a and the first pressure oil discharge recess 51b. The degree of opening of the throttle portion B 'between the communication recess 50c adjacent to the pressure oil supply recess 51a adjacent to the throttle portion B and the left steering recess 50b and the second pressure oil discharge recess 51c is between The throttle portion C 'between the pressure oil supply recess 51a and the communication recess 50c adjacent to the pressure oil supply recess 51a and the communication recess 50c is reduced. The opening of the left steering wheel is reduced, and the left steering recess 5 b and the first pressure oil discharge recess 51b and the communication pressure recess 50c adjacent to the pressure oil supply recess 51a adjacent to the right steering recess 50a and the second pressure oil discharge recess 51c. The opening degree of the throttle part D ′ increases. As a result, the pressure oil having the pressure corresponding to the steering direction and the steering resistance is supplied to the oil chamber 22 for generating the right steering assist force of the hydraulic cylinder 20 by the flow of the pressure oil indicated by the arrow in the drawing, and the left steering assist force is generated. Oil flows back from the oil chamber 23 to the tank 71, and a steering assist force to the right of the vehicle acts on the rack 16 from the hydraulic cylinder 20.
[0031]
When steered to the left, the first valve member 31 and the second valve member 32 rotate relative to each other in the direction opposite to that steered to the right, and the apertures of the throttling portions A and A ′ become smaller, and the throttling portion B , B ′ increases, apertures C and C ′ increase, and apertures D and D ′ decrease. Therefore, a steering assist force to the left of the vehicle acts on the rack 16 from the hydraulic cylinder 20.
[0032]
As shown in FIGS. 1 and 8, the variable throttle valve 60 communicating with the second outlet port 61 is formed in a second valve housing 7 ′ that can be attached to and detached from the valve housing 7, and the second valve housing 7 ′. And a cylindrical spool 62 that is inserted into the insertion hole 66 so as to be rotatable about its axis.
[0033]
A plug 68 is screwed to one end of the insertion hole 66 through a seal ring 69. The plug 68 is formed with a tool insertion hexagonal hole 68a, and a lock nut 79 is screwed onto the outer periphery thereof. The other end of the insertion hole 66 is closed by a cover 90. A stepping motor 80 is attached to the cover 90, and one end of the spool 62 is connected to the output shaft 80 a of the stepping motor 80. A controller (not shown) is connected to the stepping motor 80. The controller is connected to a vehicle speed sensor (not shown) and controls the stepping motor 80 according to the vehicle speed. As a result, the spool 62 is positioned at the standby position with the vehicle speed being zero, and is rotated so that the rotational angle in one direction increases from the standby position as the speed increases. Note that a stepping motor 80 incorporating a speed reduction mechanism may be used, or a speed reduction mechanism may be interposed between the stepping motor 80 and the spool 62.
[0034]
As shown in FIGS. 8 and 9, a pressure oil chamber 62 a is formed inside the spool 62. The pressure oil chamber 62 a is closed at one end side and the multi-end side of the spool 62. On the outer periphery of the spool 62, openings 62b communicating with the pressure oil chamber 62a are formed at four positions at equal intervals in the circumferential direction of the spool 62.
[0035]
On the inner periphery of the insertion hole 66, pressure oil discharge recesses 66 a facing the outer periphery of the spool 62 are formed at four positions at equal intervals in the circumferential direction of the spool 62.
[0036]
A throttle portion 67 whose opening is changed by the rotation of the spool 62 between an edge along the axial direction of the spool 62 in the opening 62b and an edge along the axial direction of the spool 62 in the concave portion 66a for discharging the hydraulic oil. Has been. Note that one edge of each opening 62 b constituting the throttle portion 67 is a chamfered portion 62 c along the axial direction of the spool 62. As described above, since the spool 62 is rotationally driven in accordance with the vehicle speed that is the driving condition of the vehicle, the opening degree of the throttle portion 67 changes in accordance with the vehicle speed. In this embodiment, the opening degree of the throttle portion 67 increases as the speed increases and the spool 62 rotates in the direction of the arrow P in FIG. 9, and decreases when the speed decreases and the spool 62 rotates in the direction of the arrow Q. The state shown in FIG. 9 shows a state in which the opening degree of the throttle portion 67 is the minimum, and in this embodiment, the opening degree corresponds to the gap between the outer periphery of the spool 62 and the inner periphery of the insertion hole 66, which is substantially The channel area is zero.
[0037]
A pressure oil introduction path 58 leading to one of the four openings 62b is formed in the second valve housing 7 '. The pressure oil introduction path 58 is connected to the second outlet port 61.
[0038]
As shown in FIGS. 8 and 10, a circumferential groove 66 b that communicates with each pressure oil discharge recess 66 a and faces the outer periphery of the spool 62 is formed in the inner periphery of the insertion hole 66. Pressure oil discharge passages 76 communicating with the respective pressure oil discharge recesses 66a through the circumferential grooves 66 are formed across the valve housing 7 and the second valve housing 7 '. The pressure oil discharge passage 76 communicates with the first outlet port 36.
As a result, the pressure oil supplied from the pump 70 reaches the opening 62b from the second outlet port 61 of the control valve 30 via the pressure oil introduction path 58, and from the opening 62b via the pressure oil chamber 62a. 67, and reaches the tank 71 through the pressure oil discharge recess 66 a, the circumferential groove 66 b, the pressure oil discharge path 76 and the first outlet port 36.
[0039]
As shown in FIG. 8, the spool 62 is supported by ball bearings 91 and 92 at two positions separated in the axial direction. In addition, you may support using rolling bearings other than the ball bearings 91 and 92, and sliding bearings, such as a bush. The inner ring 91 a of one ball bearing 91 is fitted on the outer periphery of the spool 62, and the outer ring 91 b is prevented from moving in the axial direction by the step 66 c on the inner periphery of the insertion hole 66 and the retaining ring 93. The inner ring 92 a of the other ball bearing 92 is fitted into a small diameter portion 62 d on the outer periphery of the spool 62, and the outer ring 92 b is fitted into an annular block 94 fitted into the insertion hole 66 through a seal ring 95. An oil seal 96 is provided between the annular block 94 and the output shaft 80 a of the motor 80.
[0040]
The plug 68 also serves as a reference position setting member. That is, as shown in FIGS. 11 (1) and 11 (2), a pair of flat receiving surfaces 68c and 68d parallel to each other are formed on the protrusion 68b formed at one end of the plug 68. It is formed parallel to the direction.
As shown in (1) and (2) of FIG. 12, a bifurcated portion 62d into which the protruding portion 68b of the plug 68 is inserted is formed at one end of the spool 62. One inner surface of the bifurcated portion 62d is composed of first and second flat surfaces 62e and 62f parallel to the axial direction of the insertion hole 66, and the other inner surface of the bifurcated portion 62d is parallel to the first flat surface 62e. The third flat surface 62g and the fourth flat surface 62h parallel to the second flat surface 62f are configured.
The distance (a + α) between the first flat surface 62e and the third flat surface 62g and the distance (a + α) between the second flat surface 62f and the fourth flat surface 62h are equal to each other, and the distance a between the receiving surfaces 68c and 68d Larger than.
Each θ formed by the first flat surface 62e and the fourth flat surface 62h and each θ formed by the second flat surface 62f and the third flat surface 62g are equal to each other, and the relative rotation of the spool 62 with respect to the protruding portion 68b is set to a predetermined value. It is determined to allow only the angle. The relative rotation angle of the spool 62 with respect to the protrusion 68b is determined so that the opening of the throttle 67 can be changed at least from the required minimum opening to the maximum opening by the relative rotation.
The contact position between one of the receiving surfaces 68c and 68d of the plug 68 and one of the first to fourth flat surfaces 62e, 62f, 62g, and 62h is set as a reference position according to the rotation angle of the spool 62. The opening degree of the throttle part 67 is controlled. The reference position can be changed by changing the screwing amount of the plug 68 into the second valve housing 7 '.
[0041]
The hydraulic pressure acting on the hydraulic cylinder 20 is controlled by the change in the opening of the throttle portion 67. That is, the maximum value of the opening degree of the throttle part 67 is the maximum value of the total opening degree of the throttle parts A ′, B ′, C ′ and D ′ belonging to the second group (relative rotation of both valve members 31 and 32). The maximum value in the characteristic that the opening degree decreases as the angle increases, that is, the maximum value of the total opening degree of the throttle parts B ′ and C ′ at the right steering, and the throttle part A ′, at the left steering. This is the maximum value of the total opening of D ′ (hereinafter, “the maximum value of the total opening” is the same)) or larger until the aperture function is not achieved. The minimum value of the opening degree of the throttle part 67 is the minimum value of the total opening degree of the throttle parts A ′, B ′, C ′ and D ′ belonging to the second group (the relative rotation angle of both valve members 31 and 32 is The minimum value in the characteristic that the opening degree decreases as it increases, that is, the minimum value of the total opening degree of the throttle parts B ′ and C ′ during the right steering, and the throttle parts A ′ and D ′ during the left steering. The minimum value of the total opening, including the fully closed state, hereinafter the same as “the minimum value of the total opening”.
[0042]
As a result, the hydraulic circuit shown in FIG. 2 is configured, and the opening of the oil passage between the throttle portions A ′, B ′, C ′, D ′ belonging to the second group and the tank 71 corresponds to the vehicle speed. This is changed by the operation of the variable throttle valve 60. That is, the pressure controlled by the throttle parts A ′, B ′, C ′, D ′ belonging to the second group of the pressure oil flow rate controlled by the throttle parts A, B, C, D belonging to the first group. The ratio to the oil flow rate is changed by the operation of the variable throttle valve 60.
[0043]
In FIG. 7, a solid line X indicates a change characteristic of the opening degree of the throttle portions A, B, C, and D belonging to the first group with respect to the relative rotation angle of both the valve members 31 and 32. An alternate long and short dash line U indicates a change characteristic of the opening degree of the throttle portions B ′ and D ′ between the communication concave portion 50c and the second pressure oil discharge concave portion 51c belonging to the second group with respect to the relative rotation angle. An alternate long and short dash line V indicates a change characteristic of the opening degree of the throttle portions A ′ and C ′ between the pressure oil supply concave portion 51a and the communication concave portion 50c belonging to the second group with respect to the relative rotation angle. A solid line Y indicates a combined change characteristic of the opening degrees of all the throttle portions A ′, B ′, C ′, and D ′ belonging to the second set with respect to the relative rotation angle. It should be noted that the change characteristics of each opening in FIG. 7 become smaller as the relative rotation angle increases, so that the change characteristics of the throttle portions B, B ′, C, and C ′ are shown during right steering. In the case of left steering, the change characteristics of the throttle portions A, A ′, D, and D ′ are shown. A broken line R indicates the opening degree of the variable throttle valve itself, which is set by the variable throttle valve 60, when the throttle unit 67 travels at medium speed. In FIG. 7, the opening is shown as a channel area.
[0044]
During low speed travel, the opening of the throttle portion 67 of the variable throttle valve 60 is minimized by the rotation of the spool 62. Therefore, the hydraulic pressure acting on the hydraulic cylinder 20 is controlled according to the change characteristic line X of the opening degree of the first set of throttle portions A, B, C, and D. In this case, as shown by a one-dot chain line in FIG. 6, even if the steering input torque is small and the relative rotation angles of both valve members 31 and 32 are small, the throttle portions A, B, C, and D belonging to the first group It is possible to reduce the opening degree and increase the rate of increase of the hydraulic pressure that generates the steering assist force, thereby satisfying the high responsiveness of the steering at low speed traveling.
[0045]
During high speed travel, the opening of the throttle portion 67 of the variable throttle valve 60 due to the rotation of the spool 62 is the maximum value of the total opening of the throttle portions A ′, B ′, C ′, D ′ belonging to the second group. That's it. Therefore, the hydraulic pressure acting on the hydraulic cylinder 20 is the change characteristic line Y of the opening of the second set of throttle portions A ′, B ′, C ′, D ′ and the first set of throttle portions A, B, C. , D is controlled in accordance with the composite characteristic of the change characteristic line X of the opening degree. In this case, as shown by the solid line in FIG. 6, unless the steering input torque is increased and the relative rotational angles of the valve members 31 and 32 are increased, the throttle portions A ′, B ′, and C ′ belonging to the second group. The opening degree of D ′ is kept large without decreasing, and the rate of increase of the hydraulic pressure that generates the steering assist force is small, so that it is possible to satisfy the stability of steering during high-speed traveling.
[0046]
During medium speed travel, the opening of the throttle portion 67 of the variable throttle valve 60 due to the displacement of the spool 62 is the minimum of the total opening of the throttle portions A ′, B ′, C ′, D ′ belonging to the second group. It is larger than the value and smaller than the maximum value. As a result, as shown in FIG. 7, until the total opening of the throttle portions A, B, C, and D belonging to the first group reaches the minimum value (in FIG. 7, the relative rotation angle of both valve members is θa Depending on the characteristics obtained by synthesizing the characteristic line R of the aperture of the throttle 67 with the change characteristic line X of the total aperture of the throttles A, B, C, D belonging to the first group. A steering assist force is applied. The total opening of the throttle parts A ′, B ′, C ′, D ′ belonging to the second group is variable from the time when the throttle parts A, B, C, D belonging to the first group are fully closed. The steering assist force is determined by the opening degree of the throttle part 67 until it becomes smaller than the opening degree of the throttle part 67 of the throttle valve 60 (the relative rotation angle of both valve members in FIG. 7 is between θa and θb). It becomes a constant value. Thereafter, when the total opening of the throttle parts A ′, B ′, C ′, D ′ belonging to the second group becomes smaller than the opening degree of the throttle part 67 of the variable throttle valve 60, the throttles belonging to the second group. A steering assist force corresponding to the change characteristic line Y of the total opening of the parts A ′, B ′, C ′, and D ′ is applied.
[0047]
After the throttle parts A, B, C, D belonging to the first group are fully closed, the total opening of the throttle parts A ′, B ′, C ′, D ′ belonging to the second group is variable. Until the opening of the throttle portion 67 of the throttle valve 60 becomes smaller (between θa and θb), the throttle portions A ′, B ′, C ′, and D ′ belonging to the second group are fully closed. And the difference (θc−θa) between the apertures A, B, C, and D belonging to the first group being in the fully closed state is reduced without reducing. That is, suppose that the throttle portions A 'and C' between the pressure oil supply recess 51a and the communication recess 50c belonging to the second set are between the communication recess 50c and the second pressure oil discharge recess 51c. As with the throttle portions B ′ and D ′, all the throttle portions A ′ belonging to the second set with respect to the relative rotation angle are assumed to have an opening change characteristic with respect to the relative rotation angle indicated by a one-dot chain line U in the figure. The combined change characteristic of the total opening degree of B ′, C ′, and D ′ is shown by a two-dot chain line M in FIG. Then, until the opening degree of the throttle parts A ′, B ′, C ′, D ′ belonging to the second group becomes smaller than the opening degree of the throttle part 67 of the variable throttle valve 60 (both valve members). Therefore, as shown by a two-dot chain line in FIG. 6, the region L in which the steering assist force cannot be controlled according to the steering resistance is increased. On the other hand, in the above-described embodiment, the closing angle θs of the throttle portions A ′ and C ′ between the pressure oil supply concave portion 51a and the communication concave portion 50c belonging to the second group is equal to that of the communication concave portion 50c. Since it is smaller than the closing angle θr of the throttle portions B ′ and D ′ between the pressure oil discharge recess 51c, the region in which the steering assist force cannot be controlled according to the steering resistance during medium speed traveling can be reduced. In addition, at the point where the throttle portions A ′ and C ′ between the pressure oil supply recess 51a and the communication recess 50c are fully closed (the relative rotation angle of both valve members in FIG. 7 is θe), contact is made. Since the throttle portions B ′ and D ′ between the concave portion 50c for use in pressure and the concave portion 51c for discharging the second pressure oil are not closed yet, the region in which the steering assist force can be controlled according to the steering resistance is not reduced.
[0048]
According to the variable throttle valve 60 configured as described above, since the opening degree of the throttle portion 67 is changed by rotating the spool 62, a screw member or spool for converting the rotational motion of the output shaft 80a of the motor 80 into linear motion. No 62 threading is required. Since the spool 62 is supported by the ball bearings 91 and 92 at two positions separated in the axial direction, swinging is suppressed. Thereby, the friction which generate | occur | produces when the outer periphery of the spool 62 is pressed on the inner periphery of the insertion hole 66 can be suppressed, and the malfunction of the spool 62 and a lock | rock can be prevented.
Further, since the pressure oil can be introduced and discharged between the both ends of the spool 62 via the pressure oil introduction path 58 and the pressure oil discharge path 76, the axial dimension of the variable throttle valve 60 can be reduced. Further, since the number of openings 62b and pressure oil discharge recesses 66a required for the number of throttle portions 67 can be reduced as much as possible, the circumferential dimension of the variable throttle valve 60 can be reduced, and the throttle portions By increasing the number 67, the flow rate of pressure oil in each throttle portion 67 can be reduced, and the flow noise caused by the generation of cavitation bubbles can be reduced.
Further, the opening degree of the throttle portion 67 can be controlled based on the contact position between the plug 68 and the spool 62, and the reference position is adjusted by changing the screwing amount of the plug 68 with respect to the second valve housing 7 '. it can. Thereby, the opening degree of the throttle part 67 can be controlled precisely.
Thereby, the spool 62 is rotated according to the driving conditions such as the vehicle speed, and the opening degree of the throttle portion 67 is changed, thereby controlling the hydraulic pressure acting on the steering assist force generating hydraulic cylinder 20 to obtain a desired steering characteristic. The hydraulic power steering device 1 that can be obtained can be configured.
[0049]
In addition, this invention is not limited to the said embodiment. For example, in the above embodiment, the spool is rotated according to the vehicle speed, but may be rotated according to other operating conditions such as a steering angle. The variable throttle valve of the present invention may be used in a hydraulic circuit of a hydraulic device other than the hydraulic power steering device.
[0050]
【The invention's effect】
According to the present invention, the variable throttle valve that is reliable in operation, compact, can reduce the generation of sound due to the flow of pressure oil, can precisely control the opening of the throttle portion, and is suitable for control of a hydraulic power steering device Can provide.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a hydraulic power steering apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a hydraulic circuit of the hydraulic power steering apparatus according to the embodiment of the present invention.
FIG. 3 is an explanatory diagram of a cross-sectional structure of a control valve in the hydraulic power steering apparatus according to the embodiment of the present invention.
FIG. 4 is a development view of a control valve in the hydraulic power steering apparatus according to the embodiment of the present invention.
FIG. 5 is an enlarged view of a main part of a control valve of the hydraulic power steering apparatus according to the embodiment of the present invention.
FIG. 6 is a diagram showing the relationship between input torque and hydraulic pressure and the relationship between the relative rotation angle of both valve members and hydraulic pressure in the hydraulic power steering apparatus according to the embodiment of the present invention.
FIG. 7 is a diagram showing the relationship between the opening degree of the throttle portion of the control valve and the relative rotation angle of the valve member in the hydraulic power steering apparatus according to the embodiment of the present invention.
FIG. 8 is a longitudinal sectional view of a variable throttle valve of the hydraulic power steering apparatus according to the embodiment of the present invention.
9 is a sectional view taken along line IX-IX in FIG.
10 is a sectional view taken along line XX in FIG.
11 is a cross-sectional view of a plug according to an embodiment of the present invention, and FIG.
12A is a plan view of the spool of the embodiment of the present invention, and FIG. 12B is a partial side view thereof.
[Explanation of symbols]
1 Hydraulic power steering system
7 'Second valve housing
20 Hydraulic cylinder
58 Pressure oil introduction path
60 Variable throttle valve
62 spool
62a Pressure oil chamber
62b opening
66 Insertion hole
66a Pressure oil discharge recess
67 Diaphragm
68 Plug (reference position setting member)
76 Pressure oil discharge passage
80 motor
91, 92 Ball bearing

Claims

A housing;
A spool that is inserted into an insertion hole formed in the housing so as to be rotatable about an axis;
A motor that rotationally drives the spool;
A throttle part whose opening degree changes due to rotation of the spool,
A bearing that supports the spool at two axially separated positions ;
A pressure oil chamber is formed inside the spool,
An opening leading to the pressure oil chamber is formed on the outer periphery of the spool,
On the inner periphery of the insertion hole, a recessed portion for discharging pressure oil that faces the outer periphery of the spool is formed,
Between the recess for pressure oil discharge and the opening is the throttle part,
A variable throttle valve in which a pressure oil introduction path that leads to the opening and a pressure oil discharge path that leads to the pressure oil discharge recess are formed in the housing .

2. The variable throttle valve according to claim 1 , wherein the pressure oil discharging recesses on the outer periphery of the spool and the inner periphery of the insertion hole are formed at a plurality of positions spaced in the circumferential direction of the spool .

A reference position setting member screwed to the housing is provided, and the contact position between the reference position setting member and the spool is used as a reference position, and the opening of the throttle portion can be controlled according to the rotation angle of the spool. The variable throttle valve according to claim 1 or 2, wherein the reference position can be changed by changing a screwing amount of the reference position setting member with respect to the housing .

The opening of the throttle can be changed according to the driving conditions of the vehicle, and the hydraulic pressure acting on the hydraulic actuator for generating the steering assist force of the hydraulic power steering device of the vehicle can be controlled by changing the opening of the throttle The variable throttle valve according to any one of claims 1 to 3 .