JP3956348B2

JP3956348B2 - Control device for electromagnetically driven valve of internal combustion engine

Info

Publication number: JP3956348B2
Application number: JP2002062336A
Authority: JP
Inventors: 重夫野村; 晃柴田; 由利夫野村; 稔夫不破
Original assignee: Denso Corp; Toyota Motor Corp
Current assignee: Denso Corp; Toyota Motor Corp
Priority date: 2002-03-07
Filing date: 2002-03-07
Publication date: 2007-08-08
Anticipated expiration: 2022-03-07
Also published as: JP2003262110A

Description

【０００１】
【発明の属する技術分野】
本発明は、内燃機関の電磁駆動式の吸排気バルブの制御方法を改善した内燃機関の電磁駆動式バルブの制御装置に関するものである。
【０００２】
【従来の技術】
電磁駆動式の吸排気バルブ装置の構成は、例えば特開２０００−２３４５３４号公報（図１２参照）に示すように、バルブハウジング１の下部に、吸気（排気）ポート２を開閉するバルブ３を組み付け、閉弁期間中には、バルブ３を閉側スプリング５によって閉弁位置に保持する。一方、バルブ３の弁シャフト４の上方には、プランジャ６を上下動自在に配置すると共に、該プランジャ６に可動鉄心７を固定し、該可動鉄心７の上下両側に、閉側コイル８と開側コイル９を所定間隔を隔てて配置している。そして、閉弁期間中は、上側の閉側コイル８に電流を流して、可動鉄心７を閉弁側（上側）に吸着保持して、プランジャ６を開側スプリング１０に抗して閉弁側（上側）に保持する。その後、開弁する時は、上側の閉側コイル８の電流を遮断して、下側の開側コイル９に電流を流し、可動鉄心７を開弁側（下側）に吸着保持して、プランジャ６で弁シャフト４を閉側スプリング５に抗して下側に押してバルブ３を開弁状態に保持する。
【０００３】
この電磁駆動式の吸排気バルブ装置を実用化する際に解決すべき大きな技術的課題の１つは、バルブ３が吸気（排気）ポート２の弁座１１に着座する際の衝突音（着座音）を小さくして低騒音化することである。これを実現するために、特開２０００−２３４５３４号公報では、バルブ３の位置（バルブリフト量）を検出する位置センサ１２と、バルブ３の速度を検出する速度センサ１３を設け、位置センサ１２で検出したバルブ３の位置（バルブリフト量）に応じて目標バルブ速度を設定して、速度センサ１３で検出した実バルブ速度と目標バルブ速度とを比較して各コイル８，９に通電する電流値を制御することで、バルブ３が弁座１１に着座する際の実バルブ速度（着座速度）がほぼ０となるように制御して着座音を低減するようにしている。
【０００４】
【発明が解決しようとする課題】
ところで、バルブ３を開弁位置から閉弁する際に、その途中で、開側スプリング１０による開弁方向のばね力と閉側スプリング９による閉弁方向のばね力とが釣り合う中立的なバルブリフト量（以下「中立位置」という）が存在し、この中立位置を境にして両スプリング９，１０の合成ばね力の作用方向が１８０°逆転する。従って、各コイル８，９の通電電流を制御する際には、中立位置を基準にしてバルブリフト量を判断して制御する必要があるが、中立位置は一定不変のものではなく、各部品の摩耗や熱膨張、スプリング９，１０の経時劣化、摺動抵抗の変化等の要因で、中立位置が変動する。もし、中立位置が変動すれば、それに応じて目標バルブ速度や制御ゲインを変化させることが望ましいが、上記従来の制御技術では、中立位置の変動が全く配慮されていないため、中立位置が変動しても、目標バルブ速度や制御ゲインは、中立位置が変動しない場合と同じ値に設定されることになる。そのため、中立位置の変動によってバルブ３の着座速度がばらついて着座音低減効果が低下したり、或は、バルブ３が弁座１１に着座する前に、バルブ３の速度が０になってバルブ３が着座せずに逆戻りするキャッチミスが発生する可能性がある。
【０００５】
本発明はこのような事情を考慮してなされたものであり、従ってその目的は、中立位置の変動を電磁駆動式バルブの制御に反映させることができ、中立位置の変動の影響を受けずに着座音を確実に低減できると共に、中立位置の変動に起因するキャッチミスを防止できる内燃機関の電磁駆動式バルブの制御装置を提供することにある。
【０００６】
【課題を解決するための手段】
上記目的を達成するために、本発明の請求項１の内燃機関の電磁駆動式バルブの制御装置は、開側スプリングによる開弁方向のばね力と閉側スプリングによる閉弁方向のばね力とが釣り合う中立的なバルブリフト量（中立位置）を内燃機関の運転中に推定する中立位置推定手段を備え、内燃機関の運転中にこの中立位置推定手段で推定した中立位置に基づいてバルブを駆動する電磁アクチュエータの通電制御を補正手段によって補正することを第１の特徴とし、更に、筒内圧力が既知となる運転状態のときに電磁アクチュエータに通電されていない期間に中立位置の推定に用いるデータをサンプリングしてそのデータに基づいて中立位置を推定することを第２の特徴とするものである。このようにすれば、内燃機関の運転中に温度上昇による各部品の熱膨張や摺動抵抗の変化等により中立位置が変動しても、内燃機関の運転中の中立位置の変動を推定して電磁駆動式バルブの制御に反映させることができ、内燃機関の運転中の中立位置の変動によってバルブの着座速度がばらつくことを防止できて、着座音を確実に低減できると共に、バルブが弁座に着座する前にバルブの速度が０になってキャッチミスが発生することを防止できる。
【０００７】
この場合、中立位置の推定は、種々の方法が考えられ、例えば、請求項３のように、内燃機関の運転中にバルブ等の可動部品の運動状態を解析する運動方程式を用いて中立位置を推定するようにしても良い。このようにすれば、内燃機関の運転中の内燃機関の温度上昇による各部品の熱膨張や摺動抵抗の変化等により、内燃機関の運転中に中立位置が変動しても、その中立位置の変動を推定することができ、内燃機関の運転中の中立位置の変動を電磁駆動式バルブの制御に反映させることができる。
【０００８】
また、請求項４のように、バルブ駆動速度がほぼ最大になるときに、バルブリフト量検出手段で検出したバルブリフト量を用いて中立位置を推定するようにすると良い。つまり、バルブ駆動速度は、中立位置付近で最大になるという特性があるため、バルブ駆動速度がほぼ最大になるときに検出したバルブリフト量を用いて中立位置を推定すれば、中立位置を精度良く推定することができる。
【０００９】
この場合、バルブ駆動速度は、前述した従来の電磁駆動式バルブの制御装置と同じように、速度センサで検出するようにしても良いが、請求項５のように、バルブリフト量検出手段で検出したバルブリフト量を時間微分してバルブ駆動速度を求めるようにしても良い。このようにすれば、速度センサを省略でき、低コスト化の要求も満たすことができる。
【００１０】
更に、請求項６のように、バルブリフト量検出手段で検出したバルブリフト量を時間微分した値をフィルタ処理してバルブ駆動速度を求めるようにしても良い。このようにすれば、ノイズや量子化問題の影響を排除してバルブ駆動速度を精度良く求めることができる。
【００１１】
ところで、内燃機関の運転中にバルブ等の可動部品の運動状態を解析する運動方程式を用いて中立位置を推定する場合、運動方程式は、バルブ等の可動部品の慣性力と各スプリングのばね力の他に、電磁アクチュエータの電磁力や筒内圧力も考慮する必要がある。しかし、バルブ駆動時に刻々と変化する電磁アクチュエータの電磁力や筒内圧力を精度良く検出又は推定することは必ずしも容易ではない。また、電磁アクチュエータの電磁力を電流値やバルブリフト量等の情報から算出することが考えられるが、演算負荷やメモリ容量が大きくなる上に、電流値等を検出するセンサの検出誤差やノイズが含まれるため、電磁アクチュエータの電磁力を精度良く算出することは容易ではない。
【００１２】
そこで、請求項１，７のように、電磁アクチュエータの電磁力及び筒内圧力が既知となる運転状態でサンプリングしたデータを用いて中立位置を推定するようにすると良い。このようにすれば、運動方程式に組み込むべき主要な外力の中で、可動部品の慣性力（＝可動部品質量×加速度）と各スプリングのばね力のみが未知となり、運動方程式の中の未知の外力が少なくなって運動方程式から中立位置を容易に且つ精度良く算出することができる。尚、可動部品の慣性力を算出する際に用いる加速度は、加速度センサで検出しても良いが、バルブ駆動速度を時間微分して求めるようにしても良い。更に、バルブ駆動速度を時間微分した値をフィルタ処理して加速度を求めるようにすれば、ノイズや量子化問題の影響を排除して加速度を精度良く求めることができる。
【００１３】
また、請求項１，８のように、電磁アクチュエータに通電されていない期間に中立位置の推定に用いるデータをサンプリングするようにしても良い。電磁アクチュエータに通電されていない期間は、電磁アクチュエータの電磁力が０となるため、電磁アクチュエータの電磁力の影響を全く受けずに中立位置を算出することができる。
【００１４】
ところで、中立位置が変動する原因は、前述したように、各部品の摩耗や熱膨張、スプリングの経時劣化、摺動抵抗の変化等であり、いずれも長い時間かかって少しずつ現れる変化であるため、サイクル毎に中立位置を毎回推定して即座に通電制御に反映させる必要はない。また、バルブが駆動されている期間は、電磁アクチュエータの通電制御を行うために演算負荷が大きくなるため、中立位置を演算する余裕がない場合がある。
【００１５】
これらの事情を考慮して、請求項２，９のように、バルブが駆動されている期間に中立位置の推定に用いるデータを周期的にサンプリングしてメモリに記憶しておき、該バルブの駆動終了後にメモリに記憶されているデータに基づいて中立位置を推定するようにしても良い。このようにすれば、バルブの駆動終了後の演算負荷が小さい時期に、余裕を持って中立位置を演算することができ、演算負荷が過負荷になることを防止できる。
【００１６】
また、請求項１０のように、排気バルブを閉弁位置から開弁して排気バルブの中立位置の推定に用いるデータをサンプリングする際に、排気バルブのリフト量が中立位置の変動範囲を越えるまでは電磁アクチュエータへの通電を停止して、排気バルブを開側スプリングと閉側スプリングとの合力のみで開弁方向に駆動し、且つ、内燃機関の負荷を強制的に低下させるようにしても良い。このようにすれば、筒内圧力の影響が大きくなる排気バルブの開弁駆動時に中立位置の推定に用いるデータをサンプリングする際に、電磁アクチュエータの電磁力を０にするために、電磁アクチュエータへの通電を停止して、排気バルブを両スプリングの合力のみで開弁方向に駆動するようにしても、内燃機関の負荷を強制的に低下させることで、排気バルブの開弁動作に対する抵抗力となる筒内圧力を低下させることができる。これにより、排気バルブを通常時とほぼ同じように開弁方向に駆動することができて、排気バルブが開弁位置で保持されないキャッチミスが発生することを防止しながら、排気バルブの中立位置の推定に用いるデータをサンプリングすることができる。
【００１７】
また、請求項１１のように、吸気バルブを閉弁位置から開弁して吸気バルブの中立位置の推定に用いるデータをサンプリングする際に、電磁アクチュエータへの通電を停止して吸気バルブを開側スプリングと閉側スプリングとの合力のみで駆動して、吸気バルブが開弁位置で保持されないキャッチミスを発生させ、このキャッチミスによる吸入空気量の減少によって発生する内燃機関のトルクダウンを無段変速機により吸収するようにしても良い。つまり、吸気バルブの開弁駆動時に中立位置の推定に用いるデータをサンプリングするために、電磁アクチュエータへの通電を停止して電磁アクチュエータの電磁力を０にすると、キャッチミスが発生して、吸気バルブの開弁時間・リフト量が不足して吸入空気量が減少し、トルクダウンが発生するが、そのトルクダウンを無段変速機により吸収することで、運転者にトルクショックを感じさせずに済む。
【００１８】
或は、請求項１２のように、吸気バルブを閉弁位置から開弁して吸気バルブの中立位置の推定に用いるデータをサンプリングする際に、電磁アクチュエータへの通電を停止してキャッチミスを発生させ、このキャッチミスによる吸入空気量の減少を抑えるためにスロットルバルブの開度を増加させるようにしても良い。このようにすれば、吸気バルブの開弁駆動時に、中立位置の推定に用いるデータをサンプリングするために、電磁アクチュエータへの通電を停止してキャッチミスを発生させても、スロットルバルブの開度を増加させることで、キャッチミスによる吸入空気量の減少を抑えることがてき、トルクダウンを抑制することができる。
【００１９】
【発明の実施の形態】
以下、本発明の一実施形態を図面に基づいて説明する。まず、図１及び図２に基づいて電磁駆動式バルブ装置全体の構造を説明する。バルブハウジング２１の下部には、吸気（又は排気）ポート２２が形成され、このポート２２の開口周縁部に円環状の弁座２３が取り付けられている。バルブハウジング２１の中心部には、バルブ２４を支持する弁シャフト２５が軸受部材２６を介して上下方向に摺動自在に挿通支持され、その上下動によりバルブ２４がポート２２を開閉する。弁シャフト２５の上部に嵌着固定されたスプリング受け部材２７とバルブハウジング２１内のスプリング収容室２８の底面部との間に閉側スプリング２９が挟み込まれ、この閉側スプリング２９の押し上げ力によって弁シャフト２５が閉弁側（上側）に付勢され、閉弁中は、この閉側スプリング２６の押し上げ力によってバルブ２４が閉弁状態に保持される。
【００２０】
一方、バルブハウジング２１の上側部には、電磁アクチュエータ３０が組み付けられている。この電磁アクチュエータ３０のハウジングは、非磁性の上ハウジング３１と非磁性の下ハウジング３２とから成り、上下の各ハウジング３１，３２に、閉側コイル３３が装着された閉側コア３４と、開側コイル３５が装着された開側コア３６とが所定の間隔を隔てて対向するように組み付けられている。閉側コア３４と開側コア３６との間には、両者の間隔を一定に保つための非磁性の環状スペーサ３７が挟み込まれ、この環状スペーサ３７の内側に平板状の可動鉄心３８が上下動自在に収容されている。この可動鉄心３８の中心部には、プランジャ３９が上下方向に貫通固定され、このプランジャ３９がハウジング３１，３２の中心部に形成された貫通孔４０，４１に上下方向に摺動自在に挿通支持されている。
【００２１】
上ハウジング３１の上面中央部に形成された円筒部４２には、開側スプリング４３を収容したスプリングケース４４が組み付けられている。このスプリングケース４４内には、プランジャ３９の上端部に固定されたスプリング受け部材４５が上下動自在に収容され、このスプリング受け部材４５とスプリングケース４４の上面部との間に開側スプリング４３が挟み込まれ、この開側スプリング４３の押し下げ力によってプランジャ３９が開弁側（下側）に付勢されている。
【００２２】
閉弁時には、上側の閉側コイル３３に駆動電流を流して、図１に示すように、可動鉄心３８を閉側コア３４の下面に吸着保持する。この状態では、プランジャ３９と弁シャフト２５との間に、これらの熱膨張を吸収するためのクリアランス４６が形成され、バルブ２４の閉弁状態が閉側スプリング２６の押し上げ力によって保持される。バルブ２４の閉弁中は、上側の閉側コイル３３に保持電流が流し続けられる。
【００２３】
一方、バルブ２４を閉弁状態から開弁する場合は、まず、上側の閉側コイル３３の保持電流を遮断して、閉側コア３４と可動鉄心３８との間の吸着状態を解除する。これにより、開側スプリング４３のばね力によって可動鉄心３８とプランジャ３９が押し下げられ、更に、プランジャ３９によって弁シャフト２５が閉側スプリング２９に抗して押し下げれる。バルブリフト量が後述する中立位置を越えるまでは、開側スプリング４３のばね力が閉側スプリング２９のばね力よりも大きいため、下側の開側コイル３５に駆動電流を流さなくても、プランジャ３９によって弁シャフト２５が閉側スプリング２９に抗して押し下げれる。そして、この開弁動作の途中から、下側の開側コイル３５に駆動電流を流して、図２に示すように、可動鉄心３８を開側コア３６の上面に吸着保持して、プランジャ３９で弁シャフト２５を閉側スプリング２９に抗して押し下げ、バルブ２４を開弁状態に保持する。バルブ２４の開弁中は、下側の開側コイル３５に保持電流が流し続けられる。
【００２４】
また、スプリングケース４４には、バルブリフト量を検出するためのリフトセンサ４７（バルブリフト量検出手段）が取り付けられている。このリフトセンサ４７は例えばギャップセンサが用いられ、プランジャ３９と一体に上下動するスプリング受け部材４５とリフトセンサ４７との間のギャップを検出することで、バルブリフト量を検出するようになっている。このリフトセンサ４７の出力信号は、図３に示すように、アンプ４８で増幅されてエンジン制御回路（以下「ＥＣＵ」と表記する）４９に入力される。
【００２５】
このＥＣＵ４９は、マイクロコンピュータを主体として構成され、クランク角センサ５０、冷却水温センサ５１、吸入空気量センサ５２、吸気温センサ５３等のエンジン運転状態を検出する各種センサの出力信号を読み込み、エンジン制御用の各プログラムによってエンジン運転状態に応じて燃料噴射量や点火時期を制御すると共に、バルブ２４の開閉タイミングや駆動速度を演算し、それに応じた制御信号を駆動回路５４に出力して電磁アクチュエータ３０の両コイル３３，３５への通電を制御する。このＥＣＵ４９の機能が特許請求の範囲でいう通電制御手段としての役割を果たす。
【００２６】
更に、ＥＣＵ４９は、内蔵されたＲＯＭ（記憶媒体）に記憶された後述する図９乃至図１１の各プログラムを実行することで、エンジン運転中にバルブ２４等の可動部品の運動状態を解析する運動方程式を用いてバルブ２４の中立位置を推定する。ここで、中立位置とは、開側スプリング４３による開弁方向のばね力と閉側スプリング２９による閉弁方向のばね力とが釣り合う中立的なバルブリフト量のことである。
【００２７】
次に、中立位置の推定方法を説明する。バルブ２４等の可動部品の運動状態を解析する運動方程式としては、ばね−マス系の運動方程式を採用する。ばね−マス系の運動方程式は、次式で表される。
Ｆ＝ｍ・ｄ²ｘ／ｄｔ²＋ｃ・ｄｘ／ｄｔ＋ｋ・ｘ ……（１）
Ｆ：ばね−マス系に働く外力
ｍ：可動部品の質量
ｘ：バルブリフト量
ｋ：両スプリング２９，４３の合成ばね定数
ｃ：粘性係数
ｄ²ｘ／ｄｔ²：加速度
ｄｘ／ｄｔ：速度
ここで、ｍ・ｄ²ｘ／ｄｔ²は可動部品の慣性力、ｃ・ｄｘ／ｄｔは摺動部の潤滑油の粘性抵抗力、ｋ・ｘは両スプリング２９，４３の合成ばね力である。
【００２８】
ばね−マス系に働く外力Ｆは、次式で表される。
Ｆ＝Ｆe −Ｆer−Ｆp −Ｆf −ｋ・ｘ₀ ……（２）
Ｆe ：両コイル３３，３５の電磁力
Ｆer：残留電磁力
Ｆp ：筒内圧力による力
Ｆf ：乾摩擦力
ｋ：両スプリング２９，４３の合成ばね定数
ｘ₀：中立位置のずれ量
ここで、電磁力Ｆe は、コイル３３，３５に電流を流しているときに発生し、残留電磁力Ｆerは、コイル３３，３５の電流を遮断した直後に誘導される電流により発生する。
【００２９】
上記（１）、（２）式から次式が導き出される。
Ｆe −Ｆer−Ｆp −Ｆf −ｋ・ｘ₀＝ｍ・ｄ²ｘ／ｄｔ²＋ｃ・ｄｘ／ｄｔ＋ｋ・ｘ ……（３）
−ｋ・ｘ₀＝ｍ・ｄ²ｘ／ｄｔ²＋ｃ・ｄｘ／ｄｔ＋ｋ・ｘ−（Ｆe −Ｆer−Ｆp −Ｆf ） ……（４）
この（４）式から次式が導き出される。
ｘ₀＝−｛ｍ・ｄ²ｘ／ｄｔ²＋ｃ・ｄｘ／ｄｔ＋ｋ・ｘ−（Ｆe −Ｆer−Ｆp −Ｆf ｝／ｋ ……（５）
【００３０】
上記（５）式において、ｍ、ｃ、ｋ、Ｆf は、予め測定又は計算しておくことができるため、未知のデータは、バルブ２４の駆動中に変化するｄ²ｘ／ｄｔ²、ｄｘ／ｄｔ、ｘ、Ｆe 、Ｆer、Ｆp であり、これらのデータが全て分かれば、上記（５）から中立位置のずれ量ｘ₀を算出することができる。
【００３１】
ここで、バルブリフト量ｘは、リフトセンサ４７の検出値を用いれば良く、また、速度ｄｘ／ｄｔは、バルブリフト量ｘを時間微分して求めれば良く、同様に、加速度ｄ²ｘ／ｄｔ²は、速度ｄｘ／ｄｔを時間微分して求めれば良い。
【００３２】
もし、Ｆe ＝Ｆer＝Ｆp ＝０の条件でバルブリフト量ｘを検出すれば、次式により中立位置のずれ量ｘ₀を算出することができる。
ｘ₀＝−（ｍ・ｄ²ｘ／ｄｔ²＋ｃ・ｄｘ／ｄｔ＋ｋ・ｘ＋Ｆf ）／ｋ……（６）
【００３３】
また、Ｆe ＝Ｆer＝０の条件でバルブリフト量ｘと筒内圧力による力Ｆp を検出又は算出すれば、次式により中立位置のずれ量ｘ₀を算出することができる。ｘ₀＝−（ｍ・ｄ²ｘ／ｄｔ²＋ｃ・ｄｘ／ｄｔ＋ｋ・ｘ＋Ｆp ＋Ｆf ）／ｋ……（７）
【００３４】
以上説明した運動方程式を用いて中立位置を推定した場合の一例が図４に示されている。図４は、リフトセンサ４７でバルブリフト量ｘを検出し、このバルブリフト量ｘを時間微分して速度ｄｘ／ｄｔを求め、更に、この速度ｄｘ／ｄｔを時間微分して加速度ｄ²ｘ／ｄｔ²を求めて、中立位置を推定したものである。この際、時間微分は、微分回路を用いてハード的に行っても良いし、ＥＣＵ４９の演算処理でソフト的に行っても良い。図４の例では、リフトセンサ４７の出力を微分回路で処理して速度ｄｘ／ｄｔを求め、更に、この速度ｄｘ／ｄｔをＥＣＵ４９の演算処理で時間微分して加速度ｄ²ｘ／ｄｔ²を求めたものである。
【００３５】
しかし、速度ｄｘ／ｄｔを単純に時間微分しただけでは、ノイズや量子化問題の影響で、加速度ｄ²ｘ／ｄｔ²ががたついてしまうため、推定中立位置もがたついてしまう。この問題を解決するには、図５に示すように、速度ｄｘ／ｄｔを時間微分した値をフィルタ処理して加速度ｄ²ｘ／ｄｔ²を求めるようにすると良い。このフィルタ処理により、ノイズや量子化問題の影響が排除されるため、加速度ｄ²ｘ／ｄｔ²の変化特性が滑らかな曲線となり、推定中立位置ががたつかなくなり、中立位置の推定精度が向上する。尚、フィルタ処理は、なまし処理（一次遅れ処理）、平均化処理等の演算手法を用いたり、ＦＩＲフィルタ等のディジタルフィルタを用いても良い。
【００３６】
図６は、中立位置を意図的にずらして、それぞれについて中立位置を推定した結果を示したものである。また、図７は、中立位置付近と推測される速度最大位置で演算した推定中立位置をプロットしたグラフである。
【００３７】
速度ｄｘ／ｄｔは、中立位置付近で最大になるという特性があるため、速度最大位置で検出したデータを用いて中立位置を推定すれば、中立位置を精度良く推定することができる。今回の実験例では、図７に示すように、推定中立位置が真値からほぼ一定値ずつオフセットされる傾向が現れたが、このオフセットは、加速度ｄ²ｘ／ｄｔ²をフィルタ処理したために発生したものと思われる。従って、製造工程で中立位置の真値を測定してオフセット量を事前に把握しておけば、中立位置の推定結果からオフセット量を補正することで、中立位置を精度良く推定することができる。
【００３８】
尚、図４に示すように、速度ｄｘ／ｄｔを時間微分して求めた加速度ｄ²ｘ／ｄｔ²ががたつく理由は、リフトセンサ４７の分解能やＡ／Ｄ変換器の分解能が不足しているためと思われるため、これらの分解能を高めれば、フィルタ処理を行う必要がなく、推定中立位置のオフセットも発生しないものと思われる。
【００３９】
ところで、中立位置の推定に用いる運動方程式には、電磁力Ｆe が含まれるが、バルブ２４の駆動時に刻々と変化する電磁力Ｆe を精度良く検出又は推定することは必ずしも容易ではない。また、この電磁力Ｆe を電流値やバルブリフト量等の情報から算出することが考えられるが、ＥＣＵ４９の演算負荷やメモリ容量が大きくなる上に、電流値等を検出するセンサの検出誤差やノイズが含まれるため、電磁力Ｆe を精度良く算出することは困難である。
【００４０】
そこで、本実施形態では、コイル３３，３５に通電されていない期間に中立位置の推定に用いるバルブリフト量ｘを検出するようにするが、通常は、キャッチミスを防止するために、バルブ２４の開閉動作中に比較的早い時期から一方のコイルに通電される。例えば、図８は、排気バルブ２４を閉弁位置から開弁するときの通電電流とバルブリフト量との関係を示しているが、通常は、キャッチミスを防止するために、排気バルブ２４のバルブリフト量が中立位置に到達する前から開側コイル３５への通電が開始される。この条件では、速度ｄｘ／ｄｔが最大となる中立位置付近では、既に開側コイル３５に通電され、電磁力Ｆe が発生しているため、速度ｄｘ／ｄｔが最大となる時期に検出したデータから中立位置を推定しようとすると、電磁力Ｆe を無視できなくなる。
【００４１】
そこで、本実施形態では、排気バルブ２４の開弁動作時に排気バルブ２４の中立位置の推定に用いるデータをサンプリングする際に、排気バルブ２４のリフト量が中立位置の変動範囲を越えるまでは開側コイル３５への通電を停止して排気バルブ２４を開側スプリング４３と閉側スプリング２９との合力のみで開弁方向に駆動する。これにより、速度ｄｘ／ｄｔが最大となる中立位置付近では、まだ開側コイル３５に通電されないため、速度ｄｘ／ｄｔが最大となる中立位置付近で検出したデータから排気バルブ２４の中立位置を推定する際に、電磁力Ｆe を無視できるようになる。
【００４２】
しかし、排気バルブ２４の開弁動作時には筒内圧力が排気バルブ２４の開弁動作を妨げる抵抗力となるため、中立位置の推定のために開側コイル３５への通電開始タイミングを遅らせると、排気バルブ２４を開弁位置で保持できないキャッチミスが発生しやすくなる。そこで、本実施形態では、開側コイル３５への通電開始タイミングを遅らせるのに対応して、エンジン負荷（例えば吸入空気量、燃料噴射量）を強制的に低下させて、筒内圧力を低下させる。これにより、中立位置の推定のために排気バルブ２４のリフト量が中立位置の変動範囲を越えるまで開側コイル３５に通電しなくても、キャッチミスを防止することができ、排気バルブ２４を確実に開弁位置に保持させることができる。
【００４３】
また、本実施形態では、吸気バルブ２４の開弁動作時に吸気バルブ２４の中立位置の推定に用いるデータを検出するために、開側コイル３５への通電を停止して吸気バルブ２４を開側スプリング４３と閉側スプリング２９との合力のみで開弁方向に駆動する。これにより、吸気バルブ２４の中立位置を推定する際に、電磁力Ｆe を無視できるようになるが、開側コイル３５への通電を停止するため、吸気バルブ２４が開弁位置で保持されないキャッチミスが発生する。このキャッチミスにより、吸気バルブ２４がばね力で閉側に戻ってくるタイミングに合わせて閉側コイル３３に通電し、吸気バルブ２４を閉側で吸引して制御不能になることを防ぐ。しかし、この動作により、吸気バルブ２４の開弁時間・リフト量が不足して吸入空気量が減少し、エンジンのトルクダウンが発生するため、このままでは、運転者にトルクショックを感じさせてしまう。そこで、本実施形態では、次の２つのいずれかの方法でトルクショックを緩和する。
【００４４】
無段変速機を搭載した車両では、吸気バルブ２４の中立位置を推定する際に発生するキャッチミスによるトルクダウンを無段変速機により吸収することで、運転者にトルクショックを感じさせないようにする。
【００４５】
或は、電子制御式のスロットルバルブを搭載した車両では、吸気バルブ２４の中立位置を推定する際に発生するキャッチミスによる吸入空気量の減少を抑えるためにスロットルバルブの開度を増加させる。これにより、キャッチミスによる吸入空気量の減少を抑えることがてき、トルクダウンを防止することができる。尚、無段変速機と電子制御式のスロットルバルブの両方を搭載した車両では、キャッチミスによるトルクショックをより効果的に緩和するために、上述したスロットルバルブの制御と無段変速機による制御とを併用するようにしても良いことは言うまでもない。
【００４６】
ところで、中立位置が変動する原因は、各部品の摩耗や熱膨張、スプリング２９，４３の経時劣化、摺動抵抗の変化等であり、いずれも長い時間かかって少しずつ現れる変化であるため、サイクル毎に中立位置を毎回推定して即座にコイル３３，３５の通電制御に反映させる必要はない。また、バルブ２４が開閉駆動されている期間は、コイル３３，３５の通電制御を行うためにＥＣＵ４９の演算負荷が大きくなるため、中立位置を演算する余裕がない場合がある。
【００４７】
そこで、本実施形態では、バルブ２４が駆動されている期間に中立位置の推定に用いるデータを周期的にサンプリングしてＥＣＵ４９のＲＡＭ等のメモリ（図示せず）に記憶しておき、該バルブ２４の駆動終了後にメモリに記憶されているデータに基づいて中立位置を推定する。このようにすれば、バルブ２４の駆動終了後のＥＣＵ４９の演算負荷が小さい時期に、余裕を持って中立位置を演算することができ、演算負荷が過負荷になることを防止できる。
以上説明した中立位置の推定は、ＥＣＵ４９により図９乃至図１１のプログラムによって実行される。以下、これら各プログラムの処理内容を説明する。
【００４８】
［中立位置推定プログラム］
図９の中立位置推定プログラムは、所定の演算周期（例えば数１０μｓ）で起動され、特許請求の範囲でいう中立位置推定手段としての役割を果たす。本プログラムが起動されると、まずステップ１０１で、バルブ２４の中立位置推定の要求が有るか否かを判定し、中立位置推定の要求がなければ、以降の処理を行うことなく、本プログラムを終了する。前述したように、中立位置が変動する原因は、各部品の摩耗や熱膨張、スプリング２９，４３の経時劣化等であり、いずれも長い時間かかって少しずつ現れる変化であるため、サイクル毎に中立位置を毎回推定する必要はなく、前回の中立位置推定時からの走行距離や冷却水温等から判断して中立位置が変動している可能性が予想される時期に、中立位置を推定すれば良い。
【００４９】
このステップ１０１で、中立位置推定の要求が有ると判断さた場合は、ステップ１０２に進み、バルブ２４の駆動中（開閉動作中）であるか否かを判定し、バルブ２４の駆動中であれば、ステップ１０３に進み、リフトセンサ４７で検出したバルブリフト量ｘと、このバルブリフト量ｘを微分回路で時間微分して求めた速度ｄｘ／ｄｔをメモリに記憶し、更に、この速度ｄｘ／ｄｔを時間微分した値をフィルタ処理して加速度ｄ²ｘ／ｄｔ²を求めてメモリに記憶する。
【００５０】
この後、ステップ１０４に進み、バルブ２４の駆動終了後の中立位置演算タイミングであるか否かを判定し、まだ中立位置演算タイミングに到達していなければ、中立位置を演算することなく、本プログラムを終了する。これにより、バルブ２４の駆動中は、所定の演算周期で中立位置の推定に用いるデータｘ、ｄｘ／ｄｔ、ｄ²ｘ／ｄｔ²のサンプリングのみが行われる。
【００５１】
その後、バルブ２４の駆動が終了して中立位置演算タイミングに到達した時点で、ステップ１０４で「Ｙｅｓ」と判定されて、ステップ１０５に進み、メモリに記憶されたデータｘ、ｄｘ／ｄｔ、ｄ²ｘ／ｄｔ²を読み込み、次のステップ１０６で、前述した運動方程式を用いて中立位置のずれ量ｘ₀を演算する。
【００５２】
ＥＣＵ４９は、このようにして求めた中立位置のずれ量ｘ₀に基づいてバルブ２４の駆動時の目標バルブ速度や制御ゲインを補正して、中立位置のずれ量ｘ₀をコイル３３，３５の通電制御に反映させる。このＥＣＵ４９の機能が特許請求の範囲でいう補正手段としての役割を果たす。
【００５３】
［方法１］
図１０の排気バルブ制御プログラムは、所定時間毎又は所定クランク角毎に起動され、まずステップ２０１で、排気バルブ２４の中立位置推定の要求が有るか否かを判定し、排気バルブ２４の中立位置推定の要求がなければ、ステップ２０２に進み、通常の排気バルブ制御を実行する。これにより、例えば排気バルブ２４の開弁駆動時には、図８に示すように、排気バルブ２４のリフト量が中立位置を越える前から開側コイル３５への通電を開始して、その電磁力により筒内圧力に抗して排気バルブ２４を開弁方向に駆動して、キャッチミスを防止し、排気バルブ２４を確実に開弁位置に吸着保持させる。この際、前回推定した中立位置のずれ量ｘ₀に基づいて排気バルブ２４の目標バルブ速度や制御ゲインが補正され、中立位置のずれ量ｘ₀が開側コイル３５の通電制御に反映される。尚、排気バルブ２４の閉弁駆動時も同様の制御が行われる。
【００５４】
一方、ステップ２０１で、排気バルブ２４の中立位置推定の要求が有ると判定された場合は、ステップ２０３に進み、エンジン負荷（例えば吸入空気量、燃料噴射量）を強制的に低下させて、筒内圧力を低下させる。そして、次のステップ２０４で、排気バルブ２４のリフト量ｘが所定量を越えたか否かを判定し、排気バルブ２４のリフト量ｘが所定量を越えるまで、開側コイル３５への通電を停止する（ステップ２０５）。ここで、所定量は、中立位置の変動範囲を少し越えた量に設定されている。これにより、排気バルブ２４の開弁駆動中に、排気バルブ２４のリフト量ｘが真の中立位置を越えるまで、開側コイル３５に通電せずに、図９の中立位置推定プログラムによって所定の演算周期で排気バルブ２４の中立位置の推定に用いるデータｘ、ｄｘ／ｄｔ、ｄ²ｘ／ｄｔ²のサンプリングのみが行われる。
【００５５】
その後、排気バルブ２４のリフト量ｘが所定量を越えた時点で、ステップ２０４で「Ｙｅｓ」と判定され、ステップ２０６に進み、開側コイル３５への通電を開始して、その電磁力により筒内圧力に抗して排気バルブ２４を開弁方向に駆動して、キャッチミスを防止し、排気バルブ２４を確実に開弁位置に吸着保持させる。この際、前回推定した中立位置のずれ量ｘ₀に基づいて排気バルブ２４の目標バルブ速度や制御ゲインが補正され、中立位置のずれ量ｘ₀が開側コイル３５の通電制御に反映される。
【００５６】
［方法２］
図１１の吸気バルブ制御プログラムは、所定時間毎又は所定クランク角毎に起動され、まずステップ３０１で、吸気バルブ２４の中立位置推定の要求が有るか否かを判定し、吸気バルブ２４の中立位置推定の要求がなければ、ステップ３０２に進み、通常の吸気バルブ制御を実行する。これにより、例えば吸気バルブ２４の開弁駆動時には、比較的早い時期から開側コイル３５への通電を開始して、その電磁力によりキャッチミスを防止し、吸気バルブ２４を確実に開弁位置に吸着保持させる。この際、前回推定した中立位置のずれ量ｘ₀に基づいて吸気バルブ２４の目標バルブ速度や制御ゲインが補正され、中立位置のずれ量ｘ₀が開側コイル３５の通電制御に反映される。尚、吸気バルブ２４の閉弁駆動時も同様の制御が行われる。
【００５７】
一方、ステップ３０１で、吸気バルブ２４の中立位置推定の要求が有ると判定された場合は、ステップ３０３に進み、吸気バルブ２４の開弁駆動時に開側コイル３５への通電を停止して、キャッチミスを発生させると共に、次のステップ３０４で、スロットル開度を増加させた上で、吸気バルブ２４がばね力で閉側に戻ってくるタイミングに合わせて閉側コイル３３に通電して閉側で再びキャッチする（ステップ３０５）。この場合、キャッチミスによる吸入空気量の減少をスロットル開度の増加で抑えることがてき、トルクダウンを抑制して運転者にトルクショックを感じさせないようにすることができる。この際、無段変速機を搭載した車両では、キャッチミスによるトルクダウンを無段変速機により吸収することで、運転者にトルクショックを感じさせないようにしても良い。このようにして、吸気バルブ２４の開弁駆動時に、開側コイル３５への通電を停止して、図９の中立位置推定プログラムによって所定の演算周期で吸気バルブ２４の中立位置の推定に用いるデータｘ、ｄｘ／ｄｔ、ｄ²ｘ／ｄｔ²のサンプリングのみが行われる。
【００５８】
以上説明した本実施形態では、エンジン運転中に、バルブ２４等の可動部品の運動状態を解析する運動方程式を用いて中立位置を推定するようにしたので、エンジン運転中のエンジンの温度上昇による各部品の熱膨張や摺動抵抗の変化等により、エンジン運転中に中立位置が変動しても、その中立位置の変動を推定することができ、エンジン運転中の中立位置の変動をバルブ２４の制御に反映させることができる。これにより、中立位置の変動によってバルブ２４の着座速度がばらつくことを防止できて、着座音を確実に低減でき、低騒音化の要求を満たすことができると共に、バルブ２４が弁座２３に着座する前にバルブ２４の速度が０になってキャッチミスが発生することを防止でき、信頼性の高い可変バルブ制御を行うことができる。
【００５９】
また、本実施形態では、リフトセンサ４７で検出したバルブリフト量を時間微分してバルブ駆動速度を求め、更に、このバルブ駆動速度を時間微分して加速度を求めるようにしたので、速度センサや加速度センサを省略でき、センサ類を少なくしてコストアップを抑えることができる。しかも、バルブ駆動速度を時間微分した値をフィルタ処理して加速度を求めるようにしたので、ノイズや量子化問題の影響を排除して加速度を精度良く求めることができる。
【００６０】
更に、本実施形態では、電磁アクチュエータ３０への通電を停止して、中立位置の推定に用いるデータをサンプリングするようにしたので、電磁アクチュエータ３０の電磁力の影響を全く受けずに中立位置を演算することができ、中立位置の演算が容易になると共に、中立位置の演算精度を向上することができる。
【００６１】
しかも、バルブ２４が駆動されている期間に中立位置の推定に用いるデータを周期的にサンプリングしてメモリに記憶しておき、該バルブ２４の駆動終了後にメモリに記憶されているデータに基づいて中立位置を推定するようにしたので、バルブ２４の駆動終了後のＥＣＵ４９の演算負荷が小さい時期に、余裕を持って中立位置を演算することができ、ＥＣＵ４９の演算負荷が過負荷になることを防止できる。
【００６２】
但し、ＥＣＵ４９のＣＰＵの演算処理能力が大きくて、バルブ２４の駆動中にコイル３３，３５の通電制御と、データのサンプリングと、中立位置の推定演算とを並行して実行するだけの余裕があれば、バルブ２４の駆動中に中立位置の推定演算を並行して実行するようにしても良いことは言うまでもない。
【００６３】
また、本実施形態では、バルブ２４の開弁駆動中に中立位置の推定に用いるデータをサンプリングするようにしたが、バルブ２４の閉弁駆動中に中立位置の推定に用いるデータをサンプリングするようにしても良い。
【００６４】
また、イグニッションスイッチのオン直後に、スタータに通電する前（エンジン運転開始直前）にリフトセンサ４７で検出したバルブリフト量を中立位置の初期値として用い、エンジン運転開始直後に運動方程式で演算した中立位置と、エンジン運転開始直前にリフトセンサ４７で検出した中立位置の初期値とを比較して、両者の差が妥当な範囲内に収まるように、運動方程式の係数を補正するようにしても良い。
【００６５】
尚、本実施形態では、リフトセンサ４７を電磁アクチュエータ３０の上方側に配置して、プランジャ３９と一体に上下動するスプリング受け部材４５とリフトセンサ４７との間のギャップを検出することで、バルブリフト量を検出するようにしたが、バルブ２４の下方にリフトセンサを配置して、バルブ２４のリフト量を直接検出するようにしたり、或は、プランジャ３９（又は弁シャフト２５）の周囲にリフトセンサを配置して、プランジャ３９（又は弁シャフト２５）の上下動量をバルブリフト量として検出するようにしても良い。
【００６６】
また、本実施形態では、吸気バルブと排気バルブの両方を電磁駆動式バルブで構成したが、いずれか一方のみを電磁駆動式バルブで構成しても良い。
【００６７】
その他、本発明は、吸気バルブ（又は排気バルブ）の閉側から開側、開側から閉側のいずれの場合でも、エンジン運転中に中立位置の推定が可能であることは言うまでもない。
【図面の簡単な説明】
【図１】本発明の一実施形態における電磁駆動式バルブ装置の閉弁時の状態を示す縦断面図
【図２】電磁駆動式バルブ装置の開弁時の状態を示す縦断面図
【図３】制御系の回路構成を概略的に示すブロック図
【図４】フィルタを用いない場合のバルブリフト量、速度、加速度、推定中立位置との関係を示す図
【図５】フィルタを用いた場合のバルブリフト量、速度、加速度、推定中立位置との関係を示す図
【図６】推定中立位置の演算特性を示す図
【図７】速度最大位置付近で中立位置を推定した場合の中立位置の推定精度を説明する図
【図８】バルブリフト量と電流との関係を説明する図
【図９】中立位置推定プログラムの処理の流れを示すフローチャート
【図１０】排気バルブ制御プログラムの処理の流れを示すフローチャート
【図１１】吸気バルブ制御プログラムの処理の流れを示すフローチャート
【図１２】従来の電磁駆動式バルブ装置の閉弁時の状態を示す縦断面図
【符号の説明】
２２…ポート、２３…弁座、２４…バルブ、２５…弁シャフト、２９…閉側スプリング、３０…電磁アクチュエータ、３３…閉側コイル、３４…閉側コア、３５…開側コイル、３６…開側コア、３８…可動鉄心、３９…プランジャ、４３…開側スプリング、４７…リフトセンサ（バルブリフト量検出手段）、４９…ＥＣＵ（通電制御手段，中立位置推定手段，補正手段）。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetically driven valve control apparatus for an internal combustion engine, which is an improved control method for an electromagnetically driven intake / exhaust valve of the internal combustion engine.
[0002]
[Prior art]
The configuration of the electromagnetically driven intake / exhaust valve device is, for example, as shown in Japanese Patent Application Laid-Open No. 2000-234534 (see FIG. 12), in which a valve 3 for opening and closing an intake (exhaust) port 2 is assembled at the bottom of the valve housing 1. During the valve closing period, the valve 3 is held in the valve closing position by the closing spring 5. On the other hand, a plunger 6 is disposed above the valve shaft 4 of the valve 3 so as to be movable up and down, and a movable iron core 7 is fixed to the plunger 6, and a closed coil 8 and an opening are opened on both upper and lower sides of the movable iron core 7. The side coils 9 are arranged at a predetermined interval. During the valve closing period, a current is passed through the upper closing coil 8 to attract and hold the movable iron core 7 on the valve closing side (upper side), and the plunger 6 is closed against the opening spring 10 on the valve closing side. Hold on (upper). Thereafter, when opening the valve, the current of the upper closed coil 8 is cut off, the current is passed through the lower open coil 9, and the movable iron core 7 is held by suction on the valve opening side (lower side). The plunger 6 pushes the valve shaft 4 downward against the closing spring 5 to keep the valve 3 open.
[0003]
One of the major technical problems to be solved when the electromagnetically driven intake / exhaust valve device is put into practical use is that a collision sound (sitting noise) when the valve 3 is seated on the valve seat 11 of the intake (exhaust) port 2. ) To reduce noise. In order to realize this, Japanese Patent Laid-Open No. 2000-234534 provides a position sensor 12 that detects the position of the valve 3 (valve lift amount) and a speed sensor 13 that detects the speed of the valve 3. A target valve speed is set in accordance with the detected position (valve lift amount) of the valve 3, and the actual valve speed detected by the speed sensor 13 is compared with the target valve speed to supply current to the coils 8 and 9. By controlling this, the actual valve speed (sitting speed) when the valve 3 is seated on the valve seat 11 is controlled so as to be substantially zero, thereby reducing the seating sound.
[0004]
[Problems to be solved by the invention]
By the way, when the valve 3 is closed from the open position, a neutral valve lift in which the spring force in the valve opening direction by the open spring 10 and the spring force in the valve closing direction by the close spring 9 are balanced. There is an amount (hereinafter referred to as “neutral position”), and the acting direction of the combined spring force of the springs 9 and 10 is reversed by 180 ° at the neutral position. Therefore, when controlling the energization currents of the coils 8 and 9, it is necessary to determine and control the valve lift amount with reference to the neutral position. However, the neutral position is not constant and does not change. The neutral position fluctuates due to factors such as wear, thermal expansion, aging of the springs 9 and 10 and changes in sliding resistance. If the neutral position fluctuates, it is desirable to change the target valve speed and control gain accordingly. However, in the above conventional control technology, the neutral position fluctuates because no consideration is given to fluctuations in the neutral position. However, the target valve speed and the control gain are set to the same values as when the neutral position does not change. For this reason, the seating speed of the valve 3 varies due to fluctuations in the neutral position and the effect of reducing the seating noise is reduced, or before the valve 3 is seated on the valve seat 11, the speed of the valve 3 becomes zero and the valve 3 There is a possibility that a catch mistake will occur without going back and sitting back.
[0005]
The present invention has been made in view of such circumstances. Therefore, the object of the present invention is to reflect the fluctuation of the neutral position in the control of the electromagnetically driven valve, without being affected by the fluctuation of the neutral position. An object of the present invention is to provide a control device for an electromagnetically driven valve of an internal combustion engine that can reliably reduce the seating noise and can prevent catch errors due to fluctuations in the neutral position.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a control device for an electromagnetically driven valve for an internal combustion engine according to claim 1 of the present invention is characterized in that the spring force in the valve opening direction by the open side spring and the spring force in the valve closing direction by the close side spring are: Neutral position estimation means for estimating a balanced neutral valve lift amount (neutral position) during operation of the internal combustion engine is provided, and the valve is driven based on the neutral position estimated by the neutral position estimation means during operation of the internal combustion engine. Correction of energization control of electromagnetic actuator by correction means In addition, in the operating state where the in-cylinder pressure is known, data used for estimating the neutral position is sampled during a period when the electromagnetic actuator is not energized, and the neutral position is determined based on the data. The second characteristic is to estimate. In this way, even if the neutral position fluctuates during operation of the internal combustion engine due to thermal expansion of each component due to temperature rise or changes in sliding resistance, the fluctuation of the neutral position during operation of the internal combustion engine is estimated. It can be reflected in the control of the electromagnetically driven valve, and it is possible to prevent variation in the seating speed of the valve due to the change of the neutral position during operation of the internal combustion engine, and to reduce the seating sound with certainty, and the valve to the valve seat It is possible to prevent a catching error from occurring due to the valve speed becoming zero before sitting.
[0007]
In this case, there are various methods for estimating the neutral position. 3 As described above, the neutral position may be estimated using a motion equation for analyzing the motion state of a movable part such as a valve during the operation of the internal combustion engine. In this way, even if the neutral position fluctuates during operation of the internal combustion engine due to thermal expansion of each component due to the temperature rise of the internal combustion engine during operation of the internal combustion engine or changes in sliding resistance, etc., The fluctuation can be estimated, and the fluctuation of the neutral position during the operation of the internal combustion engine can be reflected in the control of the electromagnetically driven valve.
[0008]
Claims 4 As described above, when the valve driving speed becomes substantially maximum, the neutral position may be estimated using the valve lift amount detected by the valve lift amount detection means. In other words, the valve drive speed has a characteristic that it becomes the maximum near the neutral position, so if the neutral position is estimated using the valve lift amount detected when the valve drive speed is almost maximum, the neutral position can be accurately determined. Can be estimated.
[0009]
In this case, the valve drive speed may be detected by a speed sensor in the same manner as the conventional electromagnetically driven valve control device described above. 5 As described above, the valve drive speed may be obtained by differentiating the valve lift amount detected by the valve lift amount detection means with respect to time. In this way, the speed sensor can be omitted and the demand for cost reduction can be satisfied.
[0010]
Further claims 6 As described above, the valve drive speed may be obtained by filtering a value obtained by time-differentiating the valve lift amount detected by the valve lift amount detection means. In this way, it is possible to accurately obtain the valve driving speed while eliminating the influence of noise and quantization problems.
[0011]
By the way, when the neutral position is estimated using an equation of motion that analyzes the motion state of a movable part such as a valve during the operation of the internal combustion engine, the equation of motion represents the inertial force of the movable part such as a valve and the spring force of each spring. In addition, it is necessary to consider the electromagnetic force of the electromagnetic actuator and the in-cylinder pressure. However, it is not always easy to accurately detect or estimate the electromagnetic force or in-cylinder pressure of the electromagnetic actuator that changes every time the valve is driven. Although it is conceivable to calculate the electromagnetic force of the electromagnetic actuator from information such as the current value and valve lift amount, the calculation load and memory capacity increase, and the detection error and noise of the sensor that detects the current value etc. Therefore, it is not easy to accurately calculate the electromagnetic force of the electromagnetic actuator.
[0012]
Therefore, the claim 1,7 As described above, the neutral position may be estimated using data sampled in an operating state in which the electromagnetic force and in-cylinder pressure of the electromagnetic actuator are known. By doing this, among the main external forces that should be incorporated into the equation of motion, only the inertial force of the movable part (= movable part mass x acceleration) and the spring force of each spring are unknown, and the unknown external force in the equation of motion is unknown. The neutral position can be calculated easily and accurately from the equation of motion. The acceleration used when calculating the inertial force of the movable part may be detected by an acceleration sensor, or may be obtained by differentiating the valve driving speed with time. Further, if the acceleration is obtained by filtering the value obtained by time differentiation of the valve driving speed, the acceleration can be obtained with high accuracy by eliminating the influence of noise and quantization problems.
[0013]
Claims 1,8 As described above, data used for estimating the neutral position may be sampled during a period when the electromagnetic actuator is not energized. During the period when the electromagnetic actuator is not energized, the electromagnetic force of the electromagnetic actuator is zero, so that the neutral position can be calculated without being affected by the electromagnetic force of the electromagnetic actuator at all.
[0014]
By the way, as described above, the cause of the fluctuation of the neutral position is wear and thermal expansion of each part, deterioration of the spring over time, change in sliding resistance, etc., all of which are changes that appear little by little over a long time. It is not necessary to estimate the neutral position every cycle and immediately reflect it in the energization control. Further, during the period in which the valve is driven, the calculation load becomes large because the energization control of the electromagnetic actuator is performed, so there is a case where there is no room for calculating the neutral position.
[0015]
Taking these circumstances into consideration, the claims 2,9 In this way, the data used for estimating the neutral position is periodically sampled and stored in the memory during the period in which the valve is driven, and the neutral is based on the data stored in the memory after the valve is driven. The position may be estimated. In this way, the neutral position can be calculated with a margin when the calculation load after the end of driving of the valve is small, and the calculation load can be prevented from being overloaded.
[0016]
Claims 10 Thus, when sampling the data used to estimate the neutral position of the exhaust valve after opening the exhaust valve from the closed position, the electromagnetic actuator must be turned on until the lift amount of the exhaust valve exceeds the fluctuation range of the neutral position. The energization may be stopped, the exhaust valve may be driven in the valve opening direction only by the resultant force of the open side spring and the close side spring, and the load on the internal combustion engine may be forcibly reduced. In this way, when sampling the data used to estimate the neutral position when opening the exhaust valve, which is affected by the in-cylinder pressure, the electromagnetic force of the electromagnetic actuator is reduced to zero. Even if energization is stopped and the exhaust valve is driven in the valve opening direction only by the resultant force of both springs, the load on the internal combustion engine is forcibly reduced to provide resistance to the valve opening operation of the exhaust valve. The in-cylinder pressure can be reduced. As a result, the exhaust valve can be driven in the valve opening direction in almost the same way as in normal times, and the neutral position of the exhaust valve can be prevented while preventing a catch error that the exhaust valve is not held in the valve open position. Data used for estimation can be sampled.
[0017]
Claims 11 When sampling the data used to estimate the neutral position of the intake valve by opening the intake valve from the closed position, the energization of the electromagnetic actuator is stopped and the intake valve is opened and closed. So that the intake valve is not held in the valve open position and a catch error is generated, and the torque reduction of the internal combustion engine caused by the reduction of the intake air amount due to the catch error is absorbed by the continuously variable transmission. Anyway. That is, in order to sample the data used for estimating the neutral position when opening the intake valve, if the energization of the electromagnetic actuator is stopped and the electromagnetic force of the electromagnetic actuator is set to 0, a catch mistake occurs and the intake valve The valve opening time / lift amount is insufficient and the intake air amount decreases, resulting in torque reduction. By absorbing the torque reduction by the continuously variable transmission, the driver does not feel a torque shock. .
[0018]
Or claims 12 When sampling the data used to estimate the neutral position of the intake valve after opening the intake valve from the closed position, the energization of the electromagnetic actuator is stopped and a catch error is generated. In order to suppress a decrease in the intake air amount, the opening of the throttle valve may be increased. In this way, in order to sample the data used to estimate the neutral position when the intake valve is opened, the throttle valve opening can be increased even if the energization of the electromagnetic actuator is stopped and a catch error occurs. By increasing, it is possible to suppress a decrease in the intake air amount due to a catch mistake, and it is possible to suppress torque reduction.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the entire structure of the electromagnetically driven valve device will be described with reference to FIGS. An intake (or exhaust) port 22 is formed in the lower part of the valve housing 21, and an annular valve seat 23 is attached to the peripheral edge of the opening of the port 22. A valve shaft 25 that supports the valve 24 is inserted and supported through a bearing member 26 in the center portion of the valve housing 21 so as to be slidable in the vertical direction, and the valve 24 opens and closes the port 22 by its vertical movement. A closing spring 29 is sandwiched between a spring receiving member 27 fitted and fixed to the upper portion of the valve shaft 25 and a bottom surface portion of a spring accommodating chamber 28 in the valve housing 21, and the valve is lifted by the pushing force of the closing spring 29. The shaft 25 is urged toward the valve closing side (upper side), and during the valve closing, the valve 24 is held in the valve closing state by the pushing force of the closing spring 26.
[0020]
On the other hand, an electromagnetic actuator 30 is assembled on the upper portion of the valve housing 21. The electromagnetic actuator 30 has a non-magnetic upper housing 31 and a non-magnetic lower housing 32. The upper and lower housings 31 and 32 are each provided with a closed core 34 having a closed coil 33 mounted thereon, and an open side. The open-side core 36 to which the coil 35 is attached is assembled so as to face it with a predetermined interval. A non-magnetic annular spacer 37 is sandwiched between the closed core 34 and the open core 36 to keep the distance between them constant, and a flat movable iron core 38 moves up and down inside the annular spacer 37. It is freely housed. A plunger 39 is fixed to the central portion of the movable iron core 38 in the vertical direction. The plunger 39 is inserted into and supported by the through holes 40 and 41 formed in the central portions of the housings 31 and 32 so as to be slidable in the vertical direction. Has been.
[0021]
A spring case 44 that houses an open-side spring 43 is assembled to the cylindrical portion 42 formed at the center of the upper surface of the upper housing 31. A spring receiving member 45 fixed to the upper end of the plunger 39 is accommodated in the spring case 44 so as to be movable up and down, and an open spring 43 is interposed between the spring receiving member 45 and the upper surface of the spring case 44. The plunger 39 is urged to the valve opening side (lower side) by the pressing force of the opening side spring 43.
[0022]
When the valve is closed, a driving current is passed through the upper closing coil 33 to attract and hold the movable iron core 38 on the lower surface of the closing core 34 as shown in FIG. In this state, a clearance 46 for absorbing these thermal expansions is formed between the plunger 39 and the valve shaft 25, and the closed state of the valve 24 is held by the pushing force of the closing spring 26. While the valve 24 is closed, the holding current continues to flow through the upper closed coil 33.
[0023]
On the other hand, when the valve 24 is opened from the closed state, first, the holding current of the upper closed side coil 33 is cut off, and the attracted state between the closed side core 34 and the movable iron core 38 is released. Thereby, the movable iron core 38 and the plunger 39 are pushed down by the spring force of the open side spring 43, and the valve shaft 25 is pushed down against the closing side spring 29 by the plunger 39. Until the valve lift amount exceeds a neutral position to be described later, the spring force of the open side spring 43 is larger than the spring force of the close side spring 29. Therefore, the plunger can be operated without applying a drive current to the lower open side coil 35. The valve shaft 25 is pushed down against the closing spring 29 by 39. Then, in the middle of this valve opening operation, a drive current is supplied to the lower open coil 35 to attract and hold the movable iron core 38 on the upper surface of the open core 36 as shown in FIG. The valve shaft 25 is pushed down against the closing spring 29, and the valve 24 is held in the open state. While the valve 24 is open, a holding current continues to flow through the lower open coil 35.
[0024]
The spring case 44 is provided with a lift sensor 47 (valve lift amount detecting means) for detecting the valve lift amount. For example, a gap sensor is used as the lift sensor 47, and the valve lift amount is detected by detecting a gap between the spring receiving member 45 that moves up and down integrally with the plunger 39 and the lift sensor 47. . The output signal of the lift sensor 47 is amplified by an amplifier 48 and input to an engine control circuit (hereinafter referred to as “ECU”) 49 as shown in FIG.
[0025]
The ECU 49 is mainly composed of a microcomputer and reads output signals of various sensors for detecting engine operating states such as the crank angle sensor 50, the cooling water temperature sensor 51, the intake air amount sensor 52, the intake air temperature sensor 53, and the like, and controls the engine. In addition to controlling the fuel injection amount and ignition timing according to the engine operating state by each program, the opening / closing timing and driving speed of the valve 24 are calculated, and the corresponding control signal is output to the driving circuit 54 to output the electromagnetic actuator 30. The current supply to both the coils 33 and 35 is controlled. The function of the ECU 49 serves as energization control means in the claims.
[0026]
Further, the ECU 49 executes each program of FIG. 9 to FIG. 11 (described later) stored in a built-in ROM (storage medium) to analyze the motion state of the movable parts such as the valve 24 during engine operation. The neutral position of the valve 24 is estimated using the equation. Here, the neutral position is a neutral valve lift amount in which the spring force in the valve opening direction by the open side spring 43 and the spring force in the valve closing direction by the close side spring 29 are balanced.
[0027]
Next, a neutral position estimation method will be described. As a motion equation for analyzing the motion state of the movable part such as the valve 24, a motion equation of a spring-mass system is adopted. The equation of motion of the spring-mass system is expressed by the following equation.
F = m · d ² x / dt ² + C · dx / dt + k · x (1)
F: External force acting on the spring-mass system
m: Mass of moving parts
x: Valve lift amount
k: Composite spring constant of both springs 29 and 43
c: Viscosity coefficient
d ² x / dt ² :acceleration
dx / dt: speed
Where m · d ² x / dt ² Is the inertial force of the movable part, c · dx / dt is the viscous resistance force of the lubricating oil in the sliding portion, and k · x is the combined spring force of the springs 29 and 43.
[0028]
The external force F acting on the spring-mass system is expressed by the following equation.
F = Fe-Fer-Fp-Ff-k.x ₀ (2)
Fe: Electromagnetic force of both coils 33 and 35
Fer: Residual electromagnetic force
Fp: Force due to in-cylinder pressure
Ff: dry friction force
k: Composite spring constant of both springs 29 and 43
x ₀ : Neutral position deviation
Here, the electromagnetic force Fe is generated when a current flows through the coils 33 and 35, and the residual electromagnetic force Fer is generated by a current induced immediately after the current of the coils 33 and 35 is cut off.
[0029]
The following equation is derived from the above equations (1) and (2).
Fe-Fer-Fp-Ff-k.x ₀ = M · d ² x / dt ² + C · dx / dt + k · x (3)
−k · x ₀ = M · d ² x / dt ² + C.dx / dt + k.x- (Fe-Fer-Fp-Ff) (4)
From the equation (4), the following equation is derived.
x ₀ =-{M · d ² x / dt ² + C.dx / dt + k.x- (Fe-Fer-Fp-Ff} / k (5)
[0030]
In the above equation (5), m, c, k, and Ff can be measured or calculated in advance, so that unknown data changes during the operation of the valve 24 d ² x / dt ² , Dx / dt, x, Fe, Fer, Fp. If all of these data are known, the deviation amount x of the neutral position from the above (5). ₀ Can be calculated.
[0031]
Here, the valve lift amount x may be the value detected by the lift sensor 47, and the speed dx / dt may be obtained by time differentiation of the valve lift amount x. Similarly, the acceleration d ² x / dt ² Can be obtained by time differentiation of the speed dx / dt.
[0032]
If the valve lift amount x is detected under the condition of Fe = Fer = Fp = 0, the neutral position deviation amount x is calculated by the following equation. ₀ Can be calculated.
x ₀ =-(M · d ² x / dt ² + C · dx / dt + k · x + Ff) / k (6)
[0033]
Further, if the valve lift amount x and the force Fp due to the in-cylinder pressure are detected or calculated under the condition of Fe = Fer = 0, the neutral position deviation amount x can be calculated by the following equation. ₀ Can be calculated. x ₀ =-(M · d ² x / dt ² + C · dx / dt + k · x + Fp + Ff) / k (7)
[0034]
An example when the neutral position is estimated using the equation of motion described above is shown in FIG. In FIG. 4, the lift sensor 47 detects the valve lift amount x, obtains the speed dx / dt by differentiating the valve lift amount x with time, and further differentiates the speed dx / dt with time. ² x / dt ² And the neutral position is estimated. At this time, the time differentiation may be performed by hardware using a differentiation circuit, or may be performed by software by calculation processing of the ECU 49. In the example of FIG. 4, the output of the lift sensor 47 is processed by a differentiating circuit to obtain a speed dx / dt, and the speed dx / dt is time-differentiated by arithmetic processing of the ECU 49 to obtain an acceleration d. ² x / dt ² Is what we asked for.
[0035]
However, if the velocity dx / dt is simply differentiated with respect to time, the acceleration d will be affected by noise and quantization problems. ² x / dt ² Since it is rattling, the estimated neutral position is also rattling. In order to solve this problem, as shown in FIG. 5, a value obtained by time-differentiating the speed dx / dt is filtered to obtain an acceleration d. ² x / dt ² It is better to ask. Since this filter process eliminates the effects of noise and quantization problems, the acceleration d ² x / dt ² The change characteristic becomes a smooth curve, the estimated neutral position does not become unstable, and the neutral position estimation accuracy is improved. Note that the filtering process may use an arithmetic technique such as an annealing process (first-order lag process) or an averaging process, or a digital filter such as an FIR filter.
[0036]
FIG. 6 shows the result of estimating the neutral position for each of the neutral positions intentionally shifted. FIG. 7 is a graph plotting the estimated neutral position calculated at the maximum speed position estimated to be near the neutral position.
[0037]
Since the speed dx / dt has a characteristic that it becomes maximum near the neutral position, if the neutral position is estimated using data detected at the maximum speed position, the neutral position can be estimated with high accuracy. In this experimental example, as shown in FIG. 7, the estimated neutral position tended to be offset from the true value by almost a constant value. ² x / dt ² This seems to be caused by filtering. Therefore, if the true value of the neutral position is measured in the manufacturing process and the offset amount is grasped in advance, the neutral position can be accurately estimated by correcting the offset amount from the neutral position estimation result.
[0038]
As shown in FIG. 4, the acceleration d obtained by differentiating the speed dx / dt with respect to time. ² x / dt ² The reason for the rattling is thought to be that the resolution of the lift sensor 47 and the resolution of the A / D converter are insufficient. Therefore, if these resolutions are increased, it is not necessary to perform filtering, and the offset of the estimated neutral position is also reduced. It seems not to occur.
[0039]
Incidentally, the equation of motion used for estimating the neutral position includes the electromagnetic force Fe. However, it is not always easy to accurately detect or estimate the electromagnetic force Fe that changes every time the valve 24 is driven. Further, it is conceivable to calculate the electromagnetic force Fe from information such as a current value and a valve lift amount. However, the calculation load and memory capacity of the ECU 49 increase, and the detection error and noise of the sensor for detecting the current value and the like are increased. Therefore, it is difficult to accurately calculate the electromagnetic force Fe.
[0040]
Therefore, in the present embodiment, the valve lift amount x used for estimating the neutral position is detected during a period in which the coils 33 and 35 are not energized. Usually, in order to prevent catch errors, the valve 24 One coil is energized from a relatively early time during the opening / closing operation. For example, FIG. 8 shows the relationship between the energization current and the valve lift amount when the exhaust valve 24 is opened from the closed position. Normally, the valve of the exhaust valve 24 is used to prevent catch errors. Energization of the open coil 35 is started before the lift amount reaches the neutral position. Under this condition, in the vicinity of the neutral position where the speed dx / dt is maximum, the open coil 35 is already energized and the electromagnetic force Fe is generated. Therefore, from the data detected at the time when the speed dx / dt is maximum. When trying to estimate the neutral position, the electromagnetic force Fe cannot be ignored.
[0041]
Therefore, in the present embodiment, when sampling the data used for estimating the neutral position of the exhaust valve 24 during the opening operation of the exhaust valve 24, the open side is kept until the lift amount of the exhaust valve 24 exceeds the fluctuation range of the neutral position. The energization of the coil 35 is stopped, and the exhaust valve 24 is driven in the valve opening direction only by the resultant force of the opening side spring 43 and the closing side spring 29. As a result, near the neutral position where the speed dx / dt is maximum, the open coil 35 is not energized yet, so the neutral position of the exhaust valve 24 is estimated from the data detected near the neutral position where the speed dx / dt is maximum. In this case, the electromagnetic force Fe can be ignored.
[0042]
However, since the in-cylinder pressure becomes a resistance force that hinders the opening operation of the exhaust valve 24 during the opening operation of the exhaust valve 24, if the energization start timing to the open coil 35 is delayed in order to estimate the neutral position, the exhaust A catch error that cannot hold the valve 24 in the open position is likely to occur. Therefore, in the present embodiment, in response to delaying the start timing of energization of the open coil 35, the engine load (for example, intake air amount, fuel injection amount) is forcibly reduced to reduce the in-cylinder pressure. . As a result, even if the open coil 35 is not energized until the lift amount of the exhaust valve 24 exceeds the neutral position fluctuation range in order to estimate the neutral position, a catch mistake can be prevented and the exhaust valve 24 can be securely connected. Can be held in the valve open position.
[0043]
In the present embodiment, in order to detect data used for estimating the neutral position of the intake valve 24 during the opening operation of the intake valve 24, the energization of the open coil 35 is stopped and the intake valve 24 is opened. The valve is driven in the valve opening direction only by the resultant force of the valve 43 and the closing spring 29. As a result, when estimating the neutral position of the intake valve 24, the electromagnetic force Fe can be ignored. However, since energization to the open coil 35 is stopped, the intake valve 24 is not held at the open position. Will occur. Due to this catch mistake, the closed coil 33 is energized in accordance with the timing when the intake valve 24 returns to the closed side by the spring force, and the intake valve 24 is prevented from being sucked on the closed side to become uncontrollable. However, due to this operation, the opening time / lift amount of the intake valve 24 is insufficient, and the intake air amount is reduced and the engine torque is reduced. Thus, the driver feels a torque shock. Therefore, in this embodiment, torque shock is mitigated by one of the following two methods.
[0044]
In a vehicle equipped with a continuously variable transmission, the continuously variable transmission absorbs torque reduction caused by a catch mistake that occurs when estimating the neutral position of the intake valve 24 so that the driver does not feel torque shock. .
[0045]
Alternatively, in a vehicle equipped with an electronically controlled throttle valve, the opening degree of the throttle valve is increased in order to suppress a decrease in the intake air amount due to a catch mistake that occurs when the neutral position of the intake valve 24 is estimated. As a result, a reduction in the intake air amount due to catch mistakes can be suppressed, and torque reduction can be prevented. In a vehicle equipped with both a continuously variable transmission and an electronically controlled throttle valve, the above-described control of the throttle valve and the control of the continuously variable transmission are used in order to alleviate torque shock due to catch mistakes more effectively. Needless to say, it may be used in combination.
[0046]
By the way, the cause of the fluctuation of the neutral position is the wear and thermal expansion of each part, the deterioration of the springs 29 and 43 with time, the change of sliding resistance, etc., all of which are changes that appear little by little over a long time. It is not necessary to estimate the neutral position every time and reflect it immediately in the energization control of the coils 33 and 35. Further, during the period in which the valve 24 is driven to open and close, the calculation load of the ECU 49 increases because the energization control of the coils 33 and 35 is performed, so there may be no room for calculating the neutral position.
[0047]
Therefore, in the present embodiment, data used for estimating the neutral position during the period in which the valve 24 is driven is periodically sampled and stored in a memory (not shown) such as a RAM of the ECU 49. The neutral position is estimated on the basis of the data stored in the memory after the driving is completed. In this way, when the calculation load of the ECU 49 after the driving of the valve 24 is small, the neutral position can be calculated with a margin, and the calculation load can be prevented from being overloaded.
The neutral position estimation described above is executed by the ECU 49 according to the programs shown in FIGS. Hereinafter, the processing contents of these programs will be described.
[0048]
[Neutral position estimation program]
The neutral position estimation program shown in FIG. 9 is activated at a predetermined calculation cycle (for example, several tens of μs) and serves as neutral position estimation means in the claims. When this program is started, it is first determined in step 101 whether or not there is a request for neutral position estimation of the valve 24. If there is no request for neutral position estimation, this program is executed without performing the subsequent processing. finish. As described above, the cause of the fluctuation of the neutral position is wear of each component, thermal expansion, deterioration of the springs 29 and 43 with time, and the like. It is not necessary to estimate the position every time, and it is only necessary to estimate the neutral position when it is expected that the neutral position may vary based on the distance traveled from the previous neutral position estimation, cooling water temperature, etc. .
[0049]
If it is determined in step 101 that there is a request for neutral position estimation, the process proceeds to step 102 to determine whether or not the valve 24 is being driven (opening / closing operation). In step 103, the valve lift amount x detected by the lift sensor 47 and the speed dx / dt obtained by time differentiation of the valve lift amount x with a differentiating circuit are stored in the memory. Further, the speed dx / Acceleration d by filtering the value obtained by time differentiation of dt ² x / dt ² Is stored in the memory.
[0050]
Thereafter, the process proceeds to step 104, where it is determined whether or not it is the neutral position calculation timing after the driving of the valve 24 is finished. If the neutral position calculation timing has not yet been reached, this program is calculated without calculating the neutral position. Exit. Thereby, during driving of the valve 24, the data x, dx / dt, d used for estimating the neutral position at a predetermined calculation cycle. ² x / dt ² Only sampling is performed.
[0051]
Thereafter, when the driving of the valve 24 is finished and the neutral position calculation timing is reached, “Yes” is determined in Step 104, the process proceeds to Step 105, and the data x, dx / dt, d stored in the memory are determined. ² x / dt ² In the next step 106, the neutral position deviation amount x is calculated using the above equation of motion. ₀ Is calculated.
[0052]
The ECU 49 determines the neutral position deviation amount x thus obtained. ₀ Based on the above, the target valve speed and control gain when the valve 24 is driven are corrected, and the neutral position deviation amount x ₀ Is reflected in the energization control of the coils 33 and 35. The function of the ECU 49 serves as correction means in the claims.
[0053]
[Method 1]
The exhaust valve control program of FIG. 10 is started at every predetermined time or every predetermined crank angle. First, at step 201, it is determined whether or not there is a request for estimating the neutral position of the exhaust valve 24, and the neutral position of the exhaust valve 24 is determined. If there is no estimation request, the routine proceeds to step 202, where normal exhaust valve control is executed. Thus, for example, when the exhaust valve 24 is driven to open, as shown in FIG. 8, the energization of the open side coil 35 is started before the lift amount of the exhaust valve 24 exceeds the neutral position, and the cylinder is driven by the electromagnetic force. The exhaust valve 24 is driven in the valve opening direction against the internal pressure to prevent a catch mistake, and the exhaust valve 24 is securely held at the valve opening position. At this time, the previously estimated neutral position deviation amount x ₀ The target valve speed and control gain of the exhaust valve 24 are corrected based on the ₀ Is reflected in the energization control of the open coil 35. The same control is performed when the exhaust valve 24 is closed.
[0054]
On the other hand, if it is determined in step 201 that there is a request for estimating the neutral position of the exhaust valve 24, the process proceeds to step 203 to forcibly reduce the engine load (for example, intake air amount, fuel injection amount) Reduce internal pressure. Then, in the next step 204, it is determined whether or not the lift amount x of the exhaust valve 24 exceeds a predetermined amount, and energization of the open side coil 35 is stopped until the lift amount x of the exhaust valve 24 exceeds the predetermined amount. (Step 205). Here, the predetermined amount is set to an amount slightly exceeding the fluctuation range of the neutral position. Thus, while the exhaust valve 24 is being driven to open, the open coil 35 is not energized until the lift amount x of the exhaust valve 24 exceeds the true neutral position, and a predetermined calculation is performed by the neutral position estimation program of FIG. Data x, dx / dt, d used for estimating the neutral position of the exhaust valve 24 in a cycle ² x / dt ² Only sampling is performed.
[0055]
Thereafter, when the lift amount x of the exhaust valve 24 exceeds a predetermined amount, it is determined as “Yes” in Step 204, the process proceeds to Step 206, energization of the open side coil 35 is started, and the cylinder is generated by the electromagnetic force. The exhaust valve 24 is driven in the valve opening direction against the internal pressure to prevent a catch mistake, and the exhaust valve 24 is securely held at the valve opening position. At this time, the previously estimated neutral position deviation amount x ₀ The target valve speed and control gain of the exhaust valve 24 are corrected based on the ₀ Is reflected in the energization control of the open coil 35.
[0056]
[Method 2]
The intake valve control program of FIG. 11 is started at predetermined time intervals or at predetermined crank angles. First, at step 301, it is determined whether or not there is a request for estimating the neutral position of the intake valve 24, and the neutral position of the intake valve 24 is determined. If there is no request for estimation, the routine proceeds to step 302 where normal intake valve control is executed. Thus, for example, when the intake valve 24 is driven to open, energization of the open side coil 35 is started from a relatively early time to prevent catch mistakes by the electromagnetic force, and the intake valve 24 is surely brought to the valve open position. Adsorb and hold. At this time, the previously estimated neutral position deviation amount x ₀ The target valve speed and control gain of the intake valve 24 are corrected based on the ₀ Is reflected in the energization control of the open coil 35. The same control is performed when the intake valve 24 is driven to close.
[0057]
On the other hand, if it is determined in step 301 that there is a request for estimating the neutral position of the intake valve 24, the process proceeds to step 303, and energization of the open side coil 35 is stopped when the intake valve 24 is driven to open and the catch is detected. In the next step 304, the throttle opening is increased, and the closing coil 33 is energized in accordance with the timing when the intake valve 24 returns to the closing side by the spring force. Catch again (step 305). In this case, a decrease in the intake air amount due to a catch mistake can be suppressed by increasing the throttle opening, and torque reduction can be suppressed so that the driver does not feel a torque shock. At this time, in a vehicle equipped with a continuously variable transmission, the torque reduction due to a catch mistake may be absorbed by the continuously variable transmission so that the driver does not feel a torque shock. In this way, when the intake valve 24 is driven to open, the energization to the open coil 35 is stopped, and the data used to estimate the neutral position of the intake valve 24 at a predetermined calculation cycle by the neutral position estimation program of FIG. x, dx / dt, d ² x / dt ² Only sampling is performed.
[0058]
In the present embodiment described above, since the neutral position is estimated using the equation of motion for analyzing the motion state of the movable part such as the valve 24 during the engine operation, each of the temperature increases due to the engine temperature during the engine operation. Even if the neutral position fluctuates during engine operation due to thermal expansion of parts or changes in sliding resistance, the fluctuation of the neutral position can be estimated, and the fluctuation of the neutral position during engine operation can be controlled by the valve 24. Can be reflected. As a result, it is possible to prevent the seating speed of the valve 24 from fluctuating due to fluctuations in the neutral position, the seating sound can be reliably reduced, the demand for low noise can be met, and the valve 24 is seated on the valve seat 23. It is possible to prevent the occurrence of a catch mistake due to the speed of the valve 24 becoming 0 before, and it is possible to perform highly reliable variable valve control.
[0059]
Further, in this embodiment, the valve lift amount detected by the lift sensor 47 is time-differentiated to obtain the valve drive speed, and further, the valve drive speed is time-differentiated to obtain the acceleration. The number of sensors can be omitted, and the number of sensors can be reduced to suppress the cost increase. In addition, since the acceleration is obtained by filtering the value obtained by differentiating the valve driving speed with respect to time, the influence of noise and quantization problems can be eliminated and the acceleration can be obtained with high accuracy.
[0060]
Furthermore, in this embodiment, since the energization to the electromagnetic actuator 30 is stopped and the data used for estimating the neutral position is sampled, the neutral position is calculated without being affected by the electromagnetic force of the electromagnetic actuator 30 at all. Thus, the neutral position can be easily calculated, and the neutral position calculation accuracy can be improved.
[0061]
In addition, data used for estimating the neutral position is periodically sampled and stored in the memory during the period in which the valve 24 is being driven, and neutralized based on the data stored in the memory after the valve 24 is driven. Since the position is estimated, the neutral position can be calculated with a margin when the calculation load of the ECU 49 after the driving of the valve 24 is small, and the calculation load of the ECU 49 is prevented from being overloaded. it can.
[0062]
However, the calculation processing capability of the CPU of the ECU 49 is large, and there is room to execute the energization control of the coils 33 and 35, the data sampling, and the neutral position estimation calculation in parallel while the valve 24 is being driven. For example, the neutral position estimation calculation may be executed in parallel while the valve 24 is being driven.
[0063]
In this embodiment, the data used for estimating the neutral position is sampled while the valve 24 is being opened, but the data used for estimating the neutral position is sampled while the valve 24 is being closed. May be.
[0064]
Further, immediately after the ignition switch is turned on, before the starter is energized (immediately before the start of engine operation), the valve lift detected by the lift sensor 47 is used as the initial value of the neutral position, and the neutral calculated by the equation of motion immediately after the start of engine operation. The position and the initial value of the neutral position detected by the lift sensor 47 immediately before the engine operation is compared, and the coefficient of the equation of motion may be corrected so that the difference between the two is within a reasonable range. .
[0065]
In the present embodiment, the lift sensor 47 is disposed above the electromagnetic actuator 30 to detect the gap between the lift sensor 47 and the spring receiving member 45 that moves up and down integrally with the plunger 39. Although the lift amount is detected, a lift sensor is arranged below the valve 24 to directly detect the lift amount of the valve 24, or the lift is lifted around the plunger 39 (or the valve shaft 25). A sensor may be arranged so that the vertical movement amount of the plunger 39 (or the valve shaft 25) is detected as the valve lift amount.
[0066]
Further, in the present embodiment, both the intake valve and the exhaust valve are configured by electromagnetically driven valves, but only one of them may be configured by an electromagnetically driven valve.
[0067]
In addition, according to the present invention, it is needless to say that the neutral position can be estimated during engine operation regardless of whether the intake valve (or the exhaust valve) is closed to open or open to closed.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a state when an electromagnetically driven valve device according to an embodiment of the present invention is closed.
FIG. 2 is a longitudinal sectional view showing a state when the electromagnetically driven valve device is opened.
FIG. 3 is a block diagram schematically showing a circuit configuration of a control system.
FIG. 4 is a diagram showing the relationship between valve lift, speed, acceleration, and estimated neutral position when no filter is used.
FIG. 5 is a diagram showing the relationship between the valve lift amount, speed, acceleration, and estimated neutral position when a filter is used.
FIG. 6 is a diagram showing calculation characteristics of an estimated neutral position
FIG. 7 is a diagram for explaining the estimation accuracy of the neutral position when the neutral position is estimated near the maximum speed position;
FIG. 8 is a diagram for explaining the relationship between the valve lift and the current
FIG. 9 is a flowchart showing a process flow of a neutral position estimation program.
FIG. 10 is a flowchart showing a processing flow of an exhaust valve control program.
FIG. 11 is a flowchart showing the flow of processing of an intake valve control program
FIG. 12 is a longitudinal sectional view showing a state when a conventional electromagnetically driven valve device is closed.
[Explanation of symbols]
22 ... Port, 23 ... Valve seat, 24 ... Valve, 25 ... Valve shaft, 29 ... Closed side spring, 30 ... Electromagnetic actuator, 33 ... Closed side coil, 34 ... Closed side core, 35 ... Open side coil, 36 ... Open Side core, 38 ... movable iron core, 39 ... plunger, 43 ... open spring, 47 ... lift sensor (valve lift amount detection means), 49 ... ECU (energization control means, neutral position estimation means, correction means).

Claims

A valve for opening and closing an intake port or an exhaust port of the internal combustion engine;
An open spring for urging the valve in the valve opening direction;
A closing spring for urging the valve in the closing direction;
An electromagnetic actuator for driving the valve in the valve opening direction against the closing spring when the valve is opened, and for driving the valve in the valve closing direction against the opening spring when the valve is closed;
Valve lift amount detecting means for detecting the valve lift amount;
Energization control means for controlling energization to the electromagnetic actuator according to the valve lift amount detected by the valve lift amount detection means and controlling the drive speed of the valve ;
A neutral valve lift amount (hereinafter referred to as “neutral position”) in which the spring force in the valve opening direction by the open side spring balances the spring force in the valve closing direction by the close side spring is estimated during operation of the internal combustion engine. Position estimation means;
In a control device for an electromagnetically driven valve of an internal combustion engine, comprising: a correction unit that corrects energization control of the electromagnetic actuator by the energization control unit based on the neutral position estimated by the neutral position estimation unit ,
The neutral position estimation means samples data used for estimating the neutral position during a period when the electromagnetic actuator is not energized in an operating state where the in-cylinder pressure is known, and determines the neutral position based on the data. A control device for an electromagnetically driven valve of an internal combustion engine characterized by estimating .

A valve for opening and closing an intake port or an exhaust port of the internal combustion engine;
An open spring for urging the valve in the valve opening direction;
A closing spring for urging the valve in the closing direction;
An electromagnetic actuator for driving the valve in the valve opening direction against the closing spring when the valve is opened, and for driving the valve in the valve closing direction against the opening spring when the valve is closed;
Valve lift amount detecting means for detecting the valve lift amount;
Energization control means for controlling energization to the electromagnetic actuator according to the valve lift amount detected by the valve lift amount detection means and controlling the drive speed of the valve;
A neutral valve lift amount (hereinafter referred to as “neutral position”) in which the spring force in the valve opening direction by the open side spring balances the spring force in the valve closing direction by the close side spring is estimated during operation of the internal combustion engine. Position estimation means;
Correction means for correcting energization control of the electromagnetic actuator by the energization control means based on the neutral position estimated by the neutral position estimation means;
In a control device for an electromagnetically driven valve of an internal combustion engine comprising:
The neutral position estimating means periodically samples and stores in a memory data used for estimating the neutral position during a period in which the valve is driven, and stores the data in the memory after the valve is driven. A control device for an electromagnetically driven valve of an internal combustion engine, wherein the neutral position is estimated based on the data stored.

3. The internal combustion engine according to claim 1, wherein the neutral position estimation unit estimates the neutral position using an equation of motion for analyzing a motion state of a movable part such as the valve during operation of the internal combustion engine. Control device for electromagnetically driven valves of engines.

The neutral position estimating means according to claim 1, wherein the estimating the neutral position using the valve lift amount of the driving speed is detected by the valve lift amount detecting means when the substantially maximum of said valve The control apparatus of the electromagnetically driven valve of the internal combustion engine in any one of.

The neutral position estimating means, the internal combustion engine according to any of claims 1 to 4, characterized in that by differentiating the valve lift amount detected by the valve lift amount detecting means time determining the driving speed of said valve Control device for electromagnetically driven valve.

6. The internal combustion engine according to claim 5 , wherein the neutral position estimating means obtains a driving speed of the valve by filtering a value obtained by time differentiation of the valve lift amount detected by the valve lift amount detecting means. Control device for electromagnetically driven valve.

3. The internal combustion engine according to claim 2 , wherein the neutral position estimation unit estimates the neutral position using data sampled in an operating state in which an electromagnetic force and an in-cylinder pressure of the electromagnetic actuator are known. Control device for electromagnetically driven valve.

3. The control device for an electromagnetically driven valve of an internal combustion engine according to claim 2 , wherein the neutral position estimating means samples data used for estimating the neutral position during a period when the electromagnetic actuator is not energized.

The neutral position estimating means periodically samples and stores in a memory data used for estimating the neutral position during a period in which the valve is being driven, and is stored in the memory after the valve is driven. 2. The control device for an electromagnetically driven valve of an internal combustion engine according to claim 1 , wherein the neutral position is estimated based on existing data.

The energization control means controls energization to the electromagnetic actuator that drives the exhaust valve,
The neutral position estimating means opens the exhaust valve from the closed position and samples data used for estimating the neutral position of the exhaust valve, so that the lift amount of the exhaust valve indicates the fluctuation range of the neutral position. Until it exceeds, the energization to the electromagnetic actuator is stopped, the exhaust valve is driven in the valve opening direction only by the resultant force of the open side spring and the close side spring, and the load of the internal combustion engine is forcibly reduced. The control device for an electromagnetically driven valve for an internal combustion engine according to any one of claims 1 to 9 .

Applied to vehicles equipped with continuously variable transmissions,
The energization control means controls energization to the electromagnetic actuator that drives the intake valve,
The neutral position estimation means stops energization of the electromagnetic actuator and opens the intake valve when sampling the data used to estimate the neutral position of the intake valve by opening the intake valve from the closed position. Driven in the valve opening direction only by the resultant force of the open side spring and the close side spring, a catch error is generated in which the intake valve is not held at the valve open position, and the intake air amount is reduced due to the catch error. electromagnetically driven control device for valves of an internal combustion engine according to any of claims 1 to 10, characterized in that to absorb the torque down of the internal combustion engine by said continuously variable transmission.

Applied to vehicles with a throttle valve in the intake passage of an internal combustion engine,
The energization control means controls energization to the electromagnetic actuator that drives the intake valve,
The neutral position estimation means stops energization of the electromagnetic actuator and opens the intake valve when sampling the data used to estimate the neutral position of the intake valve by opening the intake valve from the closed position. To drive in the valve opening direction only by the resultant force of the open side spring and the close side spring to generate a catch mistake in which the intake valve is not held in the open position, and to suppress a decrease in the intake air amount due to the catch mistake electromagnetically driven control device for valves of an internal combustion engine according to any of claims 1 to 11 characterized in that said increasing the opening degree of the throttle valve.