JP3846462B2 - Bypass valve control device for electric supercharging mechanism - Google Patents

Bypass valve control device for electric supercharging mechanism Download PDF

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Publication number
JP3846462B2
JP3846462B2 JP2003199820A JP2003199820A JP3846462B2 JP 3846462 B2 JP3846462 B2 JP 3846462B2 JP 2003199820 A JP2003199820 A JP 2003199820A JP 2003199820 A JP2003199820 A JP 2003199820A JP 3846462 B2 JP3846462 B2 JP 3846462B2
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bypass valve
pressure
upstream
downstream
electric
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JP2005042553A (en
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健一 藤村
克彦 川村
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Nissan Motor Co Ltd
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Nissan Motor Co Ltd
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/12Improving ICE efficiencies

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Description

【0001】
【発明の属する技術分野】
本発明は、電動機により駆動する過給機を備えた内燃機関の過給装置に関する。
【0002】
【従来の技術】
エンジン出力を向上させる技術として、エンジンの排気ガスにより駆動され、吸入空気を加圧するターボ過給機が知られている。しかしながらターボ過給機には、エンジン低回転域では過給できないという問題や、過給に遅れが生じる、いわゆるターボラグという問題があった。
【0003】
そこで、ターボ過給機に加えて、ターボ過給機の欠点を補うべく、電動機によって駆動する電動過給機を設置し、さらにターボ過給機と電動過給機との間の吸気通路中に閉塞手段、または切換え手段(以下、切換え手段等という)を設けて吸気通路の変更を可能とし、これら電動過給機や切換え手段等の動作を制御することで電動過給の圧力を調整する技術が特許文献1に開示されている。
【0004】
【特許文献1】
特開2002−21573号公報
【0005】
【本発明が解決しようとする課題】
しかしながら特許文献1には、切換え手段等の詳細な制御方法について記載されていない。
【0006】
実際には、切換え手段等の上流と下流の圧力差がある状態で切換え手段等を動作させると、トルクショックの発生等といった問題が生じる。例えば、電動過給機を稼働させた直後に、切換え手段等によって全ての吸気が電動過給機を通過するように吸気通路を変更すると、電動過給機の回転速度が高まっていないために電動過給機が吸気抵抗となってしまい、エンジンへ供給する吸気量が急激に減少してトルクショックを生じる。
【0007】
上記のような問題を解決するためには、切換え手段等の上流と下流の圧力差がない状態で切り替え手段等を動作させる必要があるが、圧力差を検出するために切り替え手段等の上下流に圧力センサ等を設置するとコストが増大する。
【0008】
そこで本発明では、コストを増加させることなく、適切なタイミングで切換え手段等の動作を行うことによって、加速時のトルクショックの発生を防止することを目的とする。
【0009】
【課題を解決するための手段】
本発明のバイパス弁制御装置は、エンジンの排気ガス圧力によって駆動するターボ過給機と、電動機によって駆動する電動過給機と、前記電動過給機を迂回して前記電動過給機の上流と下流の吸気通路をつなぐバイパス通路と、前記バイパス通路を開閉するバイパス弁と、前記バイパス弁の上下流のいずれか一方の吸気通路に設けた圧力検出手段と、前記圧力検出手段による検出値と吸入空気量とエンジン回転速度とから前記バイパス弁の上下流のいずれか他方の吸気通路の圧力を推定する圧力推定手段と、車両の加速要求を検出する手段と、前記加速要求を検出したときに前記バイパス弁と関連付けながら前記電動過給機による過給を行うとともに、前記バイパス弁の上下流の圧力がほぼ等しくなったときに前記バイパス弁を開弁する制御手段と、を備える。
【0010】
【作用・効果】
本発明によれば、バイパス弁の上下流の圧力差がなくなったとき、つまりバイパス弁を開いてもバイパス通路に空気が流れないときにバイパス弁を開くので、バイパス弁の開弁動作に伴うトルクショックの発生を防止できる。
【0011】
また、バイパス弁の上下流の圧力を検出方法は、一方の吸気通路内圧力は圧力センサによって検出し、他方の吸気通路内圧力は圧力検出手段によって検出された一方の吸気通路内圧力に基いて推定するので、圧力検出手段を2つ設けるのに比べてコストを低減できる。
【0012】
【発明の実施の形態】
以下本発明の実施形態を図面に基づいて説明する。
【0013】
第1実施形態について図1を用いて説明する。
【0014】
1はエンジン12の排気ガスによって駆動するターボ過給機で、エンジン12の排気ガスが排気通路50を通ってタービン1bに供給されることでタービン1bが回転し、これによってシャフト1cによってタービン1bと連結されているコンプレッサー1aも回転する。これにより、コンプレッサー1aの上流に設けたエアクリーナ13から吸入した空気を圧縮してコンプレッサー1a下流の吸気通路20に送り出す。
【0015】
ターボ過給機1の上流の吸気通路6にはエアクリーナ13とエアクリーナ13から吸入した吸気量Qaを計測するエアフローメータ(AFM)5を設置する。
【0016】
ターボ過給機1の下流の吸気通路20に駆動モータ2bによってコンプレッサー2aを駆動して過給を行う電動過給機2を設置する。
【0017】
電動過給機2は駆動モータ2bにより駆動するため、駆動開始後から回転数が高くなるまでの時間がターボ過給機1よりも短い。
【0018】
そこでエンジン12の回転数が低い領域や、いわゆるターボラグが発生する領域のように、ターボ過給機1が過給を十分に行えないときに電動過給機2を稼動させて、ターボ過給機1の欠点を補う。
【0019】
電動過給機2の上流かつターボ過給機1のコンプレッサー1a下流の吸気通路20に入口をもち、電動過給機2を迂回してエンジン12の上流かつ電動過給機2の下流の吸気通路21に出口をもつバイパス通路7を設け、このバイパス通路7にアクチュエータ3bと開閉弁3aとで構成するバイパス弁3を設ける。
【0020】
電動過給機2による過給を行うときにターボ過給機1から供給された空気をすべて電動過給機2に導くようバイパス弁3は閉じ、ターボ過給機1による過給が高まり電動過給機2による過給の必要がなくなったときにバイパス弁3を開いて空気がバイパス通路7を通るようにすることで電動過給機2が吸気通路20中で吸気抵抗となるのを防ぐ。
【0021】
ターボ過給機1から吸気通路20に送り出された空気は、電動過給機2およびバイパス通路7の両方またはいずれか一方を通過し、吸気通路21からエンジン12に供給され燃焼する。エンジン12で燃焼した後は排気通路50を通ってタービン1bに供給されタービン1bを回転させた後、排気通路51から排出される。
【0022】
電動過給機2の上流の吸気通路20に圧力センサ8を配置して電動過給機2およびバイパス弁3の上流の吸気通路内の圧力P1を検出し、検出結果をECM4に出力する。ECM4は、後述する方法によって、圧力P1に基いて電動過給機2およびバイパス弁3下流の吸気通路内の圧力P2を推定する。
【0023】
電動過給機2のシャフト2cの近傍に回転速度センサ11を配置してコンプレッサー2aの回転速度Ncを検出する。測定結果はECM4に出力される。
【0024】
また、ECM4には加速状態検出手段31からの加速状態検出信号Thも読み込まれる。加速状態検出手段31はスロットルバルブ31aの開度(あるいはアクセル開度)の変化速度を検出するもので、スロットル開度の変化速度が所定値を超えた場合に、車両が加速状態であると判断するものである。
【0025】
ECM4は図2のフローチャートに示すように、上記の圧力P1、P2、回転数Ncおよび加速状態検出信号Thに基づいて、バイパス弁3の上下流の圧力差がない状態でバイパス弁3を開閉させるようにバイパス弁3のアクチュエータ3bを制御する。
【0026】
ステップS100で加速状態検出信号Thに基いて、現在加速中であるか否かの判定を行う。加速中である場合はステップS101へ進み、加速中でない場合はステップS103へ進んでバイパス弁3を開き、ステップS104で電動過給機2を停止させる。
【0027】
ステップS101では電動過給機2が駆動中であるか否かの判定を回転速度センサ11からの検出信号に基いて行い、電動過給機2が停止していた場合にはステップS102へ進み、電動過給機2を駆動させる。電動過給機2が駆動している場合には、ステップS105へ進み、開度センサ3cからの検出信号に基いてバイパス弁3が開いているか否かの判定を行う。
【0028】
ステップS105でバイパス弁3が開いている場合は開いた状態のままにしておき、閉じている場合はステップS106に進む。
【0029】
ステップS106では、上流側圧力P1を圧力センサ8によって検出し、下流側圧力P2を上流側圧力P1に基いて以下に示す手順によって算出する。図3に上流側圧力P1、下流側圧力P2の算出方法のサブルーチンを示して説明する。
【0030】
ステップS200で圧力センサ8によって上流側圧力P1を測定し、ECM4に読込む。
【0031】
ステップS201では、以下に示すように、ECM4に読込んだ上流側圧力P1を利用して電動過給機2を通過する空気の質量流量Qsを算出する。
【0032】
圧力センサ8によって測定される上流側圧力P1を式で表すと、次式(1)のようになる。
【0033】
P1=(Qa−Qs)/V1×係数A ・・・(1)
Qa:エアクリーナ13から吸入した空気量
Qs:電動過給機2が圧送する空気量
V1:ターボ過給機1より下流かつ電動過給機2およびバイパス弁3より上流の吸気通路容積
係数A:気体定数、モル数等を含む係数
この式(1)から
Qs=Qa−(P1×V1)/係数A ・・・(2)
と表すことができる。上式(2)においてエアクリーナ13から吸入した空気量QaはAFM5、P1は圧力センサ8によって測定され、V1は予め測定しておくことが可能であるので、電動過給機2が圧送する空気量(電動過給機通過質量流量)Qsは上式(2)によって算出することが可能である。
【0034】
ステップS202では電動過給機通過質量流量Qsを利用して、以下の手順により下流側圧力P2を算出する。
【0035】
圧力P2は次式(3)で表すことができる。
【0036】
P2=(Qs−Qe)/V2×係数B ・・・(3)
Qs:電動過給機2が圧送する空気量
Qe:エンジン12に供給される空気量
V2:電動過給機2およびバイパス弁3より下流かつスロットルバルブ31aより上流の吸気通路容積
係数B:気体定数、モル数等を含む係数
ここでエンジン12に供給される空気量Qeはクランク角センサ33によって検出されるエンジン回転速度Neを用いて次式(4)のように表すことができる。
【0037】
Qe=Ne×係数C ・・・(4)
上式(2)、(4)を式(3)に代入することにより、P2は次式(5)のように表すことができる。
【0038】
P2={Qa−(P1×V1/係数A)−(Ne×係数C)}/V2×係数B ・・・(5)
上式(5)においてエアクリーナ13から吸入した空気量Qa、エンジン回転速度Neは前述したようにそれぞれAFM5、クランク角センサ33によって測定可能であり、また、吸気通路20の容積V1、吸気通路21の容積V2、および各係数は予め求めておくことが可能である。したがって式(5)に各値を代入することによって下流側の圧力P2を計算によって求めることが可能である。
【0039】
上記のように上流側圧力P1と下流側圧力P2とを推定したら、ステップS107に進み、前述したステップで求めた圧力P1、P2に基いて、バイパス弁3が閉弁状態から開弁状態までに要する時間(動作時間)T(s)後の上流側圧力Pt1および下流側圧力Pt2を求める。これは、バイパス弁3が閉弁状態から完全に開弁状態になるまでには動作時間T(s)を要し、この間も圧力は変化しているからである。なお、動作時間T(s)は予め実験等により調べておく。
【0040】
具体的な算出方法は、図4に示すサブルーチンの通りである。
【0041】
ステップS300で上流側圧力P1と下流側圧力P2について、前回の計算値と今回の計算値とから単位時間当たりの増加量△P1、△P2を算出する。この増加量△P1、△P2を用いて動作時間T(s)後の予測圧力圧力Pt1、Pt2を表すと、式(6)、(7)のようになる。
【0042】
Pt1=△P1×T+P1 ・・・(6)
Pt2=△P2×T+P2 ・・・(7)
△P1、△P2:動作時間T(s)中の単位時間当たりの圧力増加量
ステップS301では、動作時間T(s)後の上下流の圧力をより正確に求める為に、図5、図6に示すテーブル、マップを用いて増加量△P1の補正値hosei1、および増加量△P2の補正値hosei2を求める。
図5は補正値hosei1をエンジン回転速度に割付けたテーブルであり、エンジン12が低回転域では回転数が高くなるに連れて補正値hosei1が大きくなり1に近づき、中間領域では回転速度によらず1であり、高回転域では回転速度が大きくなるに連れて小さくなる。このテーブルからエンジン回転速度によって検索することにより補正値hosei1を求める。
【0043】
図6は図5のテーブルに変数として駆動モータ回転速度を加えた3次元マップであり、エンジン回転速度とモータ回転速度の両方、もしくは一方が低回転域の場合は、回転速度が高くなるほど補正値hosei2が大きくなり1に近づき、両方が中間域の場合は回転速度によらず1であり、両方もしくはいずれか一方が高回転域の場合は、回転速度が高くなるほど補正値hosei2は小さくなる。このマップからエンジン回転速度、駆動モータ回転速度によって検索することにより補正値hosei2を求める。
【0044】
ステップS302では上記で求めた補正値hosei1、hosei2を用いて増加量△P1、△P2を補正し、△P1h、△P2hとする。
△P1h=△P1×hosei1 ・・・(8)
△P2h=△P2×hosei2 ・・・(9)
ステップS303では補正後の増加量△P1h、△P2hを用いて、次式(10)、(11)のように動作時間T(s)後の上下流の予測圧力Pt1、Pt2を算出する。
【0045】
Pt1=△P1h×T+P1 ・・・(10)
Pt2=△P2h×T+P2 ・・・(11)
次に図2のフローチャートに戻る。
【0046】
ステップS108では、上記のように求めた予測圧力Pt1、Pt2を比較し、上流側予測圧力Pt1が下流側予測圧力Pt2以上となった場合にはステップS109に進み、バイパス弁3を開き、上流側予測圧力Pt1が下流側予測圧力Pt2より小さい場合にはステップS106に戻る。
【0047】
ここで、開弁するか否かの判定に、予測圧力Pt1、Pt2を用いる理由について説明する。バイパス弁3の上流側圧力P1と下流側圧力P2が等しくなってからバイパス弁3を開くと、バイパス弁3が完全に開くまではバイパス弁3によって吸気通路断面積が絞られているので、上流側圧力P1が上昇し続けて下流側圧力P2より高くなる。つまりバイパス弁3が吸気抵抗となって、エンジン12に要求通りの空気量が供給されなくなる。
【0048】
そこで、バイパス弁3が完全に開いたときにバイパス弁3の上下流の圧力が等しくなるようにするために、バイパス弁3の動作時間T(s)の間の圧力上昇を考慮した予測圧力Pt1、Pt2を用いる。
【0049】
上記のように本実施形態では、上流側圧力P1は圧力センサ8によって検出し、下流側圧力P2は上流側圧力P1を用いて推定し、これらに基いてバイパス弁3の動作時間後の予測圧力Pt1、Pt2を算出し、予測圧力Pt1、Pt2が等しくなったときにバイパス弁3に開弁指令を出す。
【0050】
以上により、本実施形態では、バイパス弁3が全開になったときにバイパス弁3及び電動過給機2の上下流の圧力P1、P2が等しくなるタイミングでバイパス弁3の開弁動作を開始するので、バイパス弁3を開閉してもバイパス通路7を空気が流れることがなく、これによりエンジン出力のトルクショックが発生することを防止できる。
【0051】
バイパス弁3及び電動過給機2の下流側圧力P2は、圧力センサ8によって検出するバイパス弁上流側圧力P1とエンジン回転速度および吸入空気量に基いて推定するので、下流側圧力P2測定用に別途圧力センサを設置するよりもコストを低減することができ、また、上下流ともに圧力センサを設置せずに推定するよりも正確に圧力を推定できる。
【0052】
なお、圧力センサ8を下流側に設けて下流側圧力P2を検出し、検出したP2に基いて上流側圧力P1を推定する方法でも同様の効果が得られる。この場合は、上流側圧力P1は、以下のように求まる。
【0053】
圧力センサ8によって検出した下流側圧力P2は式(12)のように表すことができる。
【0054】
P2=(Qs−Qe)/V2×係数B ・・・(12)
これを変形して
Qs=Qe+(P2×V2)/係数B ・・・(13)
とする。ここで、Qe=Ne(エンジン回転速度)×係数CであるからQsは次式(13)で表すことができる。
【0055】
Qs=(Ne×C)+(P2×V2)/係数B ・・・(14)
そして、式(3)および式(14)を式(1)に代入することによって上流側圧力P1は式(15)のように表すことができる。
【0056】
P1={Qa−(P2×V2)/係数B−(Ne×係数C)}/V1×係数A
・・・(15)
ここで、圧力センサ8をバイパス弁3の上下流のどちらに設置した方が良いかについて説明する。
【0057】
圧力センサ8をバイパス弁3の上下流のどちらに設置した場合にも、検出した一方の圧力値は電動過給機2を通過する空気量Qsを求めるのに利用し、この空気量Qsから他方の圧力値を推定している。
【0058】
ただし、上流側に設置した場合には、空気量Qsは式(2)のように表され、下流側に設置した場合には、空気量Qsは式(13)のように表される。
【0059】
Qs=Qa−(P1×V1)/係数A ・・・(2)
Qs=Qe+(P2×V2)/係数B ・・・(13)
つまり、電動過給機2を通過する空気量Qsの精度は、上流側に圧力センサ8を設置した場合にはエアフローメータ5で計測した吸気量Qaの精度に依存し、下流側に設置した場合にはエンジン回転速度Neから計算によって算出した空気量Qeの精度に依存することになる。エアフローメータ5によって直接計測した値とクランク角センサ33によって検出したエンジン回転速度Neを用いて計算によって求めた値とを比較すれば、エアフローメータ5によって直接計測した値の方が精度が高いと考えられるので、圧力センサ8は上流側に設ける方がより高精度な推定を行うことが可能であると考えられる。
【0060】
また、上流側に圧力センサ8を設置した場合にはターボ過給機1によって圧縮された空気の圧力を測定するのに対して、下流側に圧力センサ8を設置した場合には、ターボ過給機1によって圧縮された後さらに電動過給機2によって圧縮された空気の圧力を測定することになり、圧縮による温度上昇の影響が大きくなる。このことからも、圧力センサ8は上流側に設置した方がより高精度な推定を行うことが可能であると考えられる。
【0061】
なお、本発明は上記の実施の形態に限定されるわけではなく、特許請求の範囲に記載の技術的思想の範囲内で様々な変更を成し得ることは言うまでもない。
【図面の簡単な説明】
【図1】本発明の実施形態のシステム構成を表す図である。
【図2】ECMが実行するバイパス弁制御のフローチャートである。
【図3】上流側に設置した圧力センサの検出値から下流側の圧力を推定するサブルーチンのフローチャートである。
【図4】バイパス弁の開弁動作中の圧力上昇を考慮して吸気通路内圧力を推定するフローチャートである。
【図5】バイパス弁動作中の圧力上昇の傾きの補正値をエンジン回転速度に割付けたテーブルである。
【図6】バイパス弁動作中の圧力上昇の傾きの補正値をエンジン回転数およびモータ回転速度に割付けた3次元マップである。
【符号の説明】
1 ターボ過給機
2 電動過給機
2a コンプレッサ
2b 駆動モータ
2c シャフト
3 バイパス弁
4 コントロールユニット(ECM)
5 エアフローメータ(AFM)
6 吸気通路
7 バイパス通路
8 圧力センサ
11 回転速度センサ
12 エンジン
13 エアクリーナ
20 吸気通路(上流側)
21 吸気通路(下流側)
31 スロットルバルブ
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a supercharging device for an internal combustion engine including a supercharger driven by an electric motor.
[0002]
[Prior art]
As a technique for improving engine output, a turbocharger that is driven by engine exhaust gas and pressurizes intake air is known. However, the turbocharger has a problem that turbocharging cannot be performed in a low engine speed range and a so-called turbo lag in which supercharging is delayed.
[0003]
Therefore, in addition to the turbocharger, in order to compensate for the shortcomings of the turbocharger, an electric supercharger that is driven by an electric motor is installed, and in the intake passage between the turbocharger and the electric supercharger. Technology that adjusts the pressure of electric supercharging by providing closing means or switching means (hereinafter referred to as switching means, etc.) so that the intake passage can be changed and by controlling the operation of these electric superchargers, switching means, etc. Is disclosed in Patent Document 1.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-21573
[Problems to be solved by the present invention]
However, Patent Document 1 does not describe a detailed control method such as switching means.
[0006]
Actually, if the switching means or the like is operated in a state where there is a pressure difference between the upstream and downstream of the switching means or the like, problems such as generation of a torque shock occur. For example, if the intake passage is changed so that all intake air passes through the electric supercharger immediately after the electric supercharger is operated, the rotation speed of the electric supercharger is not increased. The turbocharger becomes an intake resistance, and the amount of intake air supplied to the engine is rapidly reduced, resulting in a torque shock.
[0007]
In order to solve the above problems, it is necessary to operate the switching means in a state where there is no pressure difference between the upstream and downstream of the switching means etc., but in order to detect the pressure difference, the upstream and downstream of the switching means etc. If a pressure sensor or the like is installed in the door, the cost increases.
[0008]
Therefore, an object of the present invention is to prevent the occurrence of torque shock during acceleration by performing an operation of a switching means or the like at an appropriate timing without increasing the cost.
[0009]
[Means for Solving the Problems]
The bypass valve control device of the present invention includes a turbocharger driven by an exhaust gas pressure of an engine, an electric supercharger driven by an electric motor, and an upstream of the electric supercharger bypassing the electric supercharger. A bypass passage connecting the downstream intake passage, a bypass valve for opening and closing the bypass passage, a pressure detection means provided in one of the intake passages upstream and downstream of the bypass valve, and a detection value and suction by the pressure detection means A pressure estimating means for estimating the pressure of the other intake passage upstream and downstream of the bypass valve from the air amount and the engine speed, a means for detecting a request for acceleration of the vehicle, and when the acceleration request is detected, Control that performs supercharging by the electric supercharger in association with the bypass valve and opens the bypass valve when the upstream and downstream pressures of the bypass valve become substantially equal It includes a stage, a.
[0010]
[Action / Effect]
According to the present invention, when the pressure difference between the upstream and downstream sides of the bypass valve disappears, that is, when the bypass valve is opened and no air flows into the bypass passage, the bypass valve is opened. Shock can be prevented.
[0011]
Further, in the method of detecting the pressure upstream and downstream of the bypass valve, the pressure in one intake passage is detected by a pressure sensor, and the pressure in the other intake passage is based on the pressure in one intake passage detected by the pressure detecting means. Since the estimation is performed, the cost can be reduced as compared with the case where two pressure detecting means are provided.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0013]
A first embodiment will be described with reference to FIG.
[0014]
1 is a turbocharger that is driven by exhaust gas of the engine 12. The exhaust gas of the engine 12 is supplied to the turbine 1 b through the exhaust passage 50, thereby rotating the turbine 1 b, whereby the shaft 1 c and the turbine 1 b are rotated. The connected compressor 1a also rotates. Thereby, the air sucked from the air cleaner 13 provided upstream of the compressor 1a is compressed and sent out to the intake passage 20 downstream of the compressor 1a.
[0015]
In the intake passage 6 upstream of the turbocharger 1, an air cleaner 13 and an air flow meter (AFM) 5 for measuring the intake air amount Qa taken from the air cleaner 13 are installed.
[0016]
An electric supercharger 2 that performs supercharging by driving the compressor 2a by the drive motor 2b is installed in the intake passage 20 downstream of the turbocharger 1.
[0017]
Since the electric supercharger 2 is driven by the drive motor 2b, the time from the start of driving until the rotational speed becomes higher is shorter than that of the turbocharger 1.
[0018]
Therefore, the turbocharger 2 is operated when the turbocharger 1 cannot sufficiently perform supercharging, such as in a region where the rotational speed of the engine 12 is low or a region where a so-called turbo lag is generated. Make up for the first drawback.
[0019]
An intake passage 20 having an inlet upstream of the electric supercharger 2 and downstream of the compressor 1 a of the turbocharger 1 bypasses the electric supercharger 2 and is upstream of the engine 12 and downstream of the electric supercharger 2. A bypass passage 7 having an outlet is provided at 21, and a bypass valve 3 including an actuator 3 b and an on-off valve 3 a is provided in the bypass passage 7.
[0020]
The bypass valve 3 is closed so that all the air supplied from the turbocharger 1 is guided to the electric supercharger 2 when supercharging by the electric supercharger 2 is performed. When the supercharge by the charger 2 is no longer necessary, the bypass valve 3 is opened so that air passes through the bypass passage 7, thereby preventing the electric supercharger 2 from becoming an intake resistance in the intake passage 20.
[0021]
The air sent from the turbocharger 1 to the intake passage 20 passes through one or both of the electric supercharger 2 and the bypass passage 7 and is supplied to the engine 12 from the intake passage 21 and combusts. After combustion in the engine 12, the exhaust gas is supplied to the turbine 1 b through the exhaust passage 50, rotates the turbine 1 b, and is then discharged from the exhaust passage 51.
[0022]
The pressure sensor 8 is disposed in the intake passage 20 upstream of the electric supercharger 2 to detect the pressure P1 in the intake passage upstream of the electric supercharger 2 and the bypass valve 3, and the detection result is output to the ECM 4. The ECM 4 estimates the pressure P2 in the intake passage downstream of the electric supercharger 2 and the bypass valve 3 based on the pressure P1 by a method described later.
[0023]
A rotational speed sensor 11 is arranged in the vicinity of the shaft 2c of the electric supercharger 2 to detect the rotational speed Nc of the compressor 2a. The measurement result is output to ECM4.
[0024]
Further, the acceleration state detection signal Th from the acceleration state detection means 31 is also read into the ECM 4. The acceleration state detection means 31 detects the changing speed of the opening degree (or accelerator opening degree) of the throttle valve 31a, and determines that the vehicle is in an accelerating state when the changing speed of the throttle opening exceeds a predetermined value. To do.
[0025]
As shown in the flowchart of FIG. 2, the ECM 4 opens and closes the bypass valve 3 based on the pressures P1 and P2, the rotational speed Nc, and the acceleration state detection signal Th in a state where there is no pressure difference between the upstream and downstream of the bypass valve 3. Thus, the actuator 3b of the bypass valve 3 is controlled.
[0026]
In step S100, it is determined whether the vehicle is currently accelerating based on the acceleration state detection signal Th. When it is accelerating, it progresses to step S101, and when not accelerating, it progresses to step S103, the bypass valve 3 is opened, and the electric supercharger 2 is stopped by step S104.
[0027]
In step S101, it is determined whether or not the electric supercharger 2 is being driven based on a detection signal from the rotation speed sensor 11. If the electric supercharger 2 has stopped, the process proceeds to step S102. The electric supercharger 2 is driven. When the electric supercharger 2 is driven, the process proceeds to step S105, and it is determined whether or not the bypass valve 3 is open based on the detection signal from the opening degree sensor 3c.
[0028]
If the bypass valve 3 is open in step S105, it is left open, and if it is closed, the process proceeds to step S106.
[0029]
In step S106, the upstream pressure P1 is detected by the pressure sensor 8, and the downstream pressure P2 is calculated by the following procedure based on the upstream pressure P1. FIG. 3 shows a subroutine of a method for calculating the upstream pressure P1 and the downstream pressure P2.
[0030]
In step S200, the upstream pressure P1 is measured by the pressure sensor 8 and read into the ECM4.
[0031]
In step S201, as shown below, the mass flow rate Qs of air passing through the electric supercharger 2 is calculated using the upstream pressure P1 read into the ECM 4.
[0032]
The upstream pressure P1 measured by the pressure sensor 8 is expressed by the following equation (1).
[0033]
P1 = (Qa−Qs) / V1 × coefficient A (1)
Qa: Air amount sucked from the air cleaner 13 Qs: Air amount pumped by the electric supercharger 2 V1: Intake passage volume coefficient A: gas downstream of the turbocharger 1 and upstream of the electric supercharger 2 and bypass valve 3 Coefficient including constant, number of moles, etc. From this equation (1), Qs = Qa− (P1 × V1) / coefficient A (2)
It can be expressed as. In the above equation (2), the air amount Qa sucked from the air cleaner 13 is measured by the AFM 5, P 1 is measured by the pressure sensor 8, and V 1 can be measured in advance, so that the amount of air pumped by the electric supercharger 2 (Electric supercharger passing mass flow rate) Qs can be calculated by the above equation (2).
[0034]
In step S202, the downstream pressure P2 is calculated by the following procedure using the electric supercharger passage mass flow rate Qs.
[0035]
The pressure P2 can be expressed by the following formula (3).
[0036]
P2 = (Qs−Qe) / V2 × coefficient B (3)
Qs: Air amount pumped by the electric supercharger 2 Qe: Air amount supplied to the engine 12 V2: Intake passage volume coefficient B downstream of the electric supercharger 2 and bypass valve 3 and upstream of the throttle valve 31a B: Gas constant The coefficient including the number of moles, etc. Here, the amount of air Qe supplied to the engine 12 can be expressed by the following equation (4) using the engine rotational speed Ne detected by the crank angle sensor 33.
[0037]
Qe = Ne × coefficient C (4)
By substituting the above equations (2) and (4) into the equation (3), P2 can be expressed as the following equation (5).
[0038]
P2 = {Qa− (P1 × V1 / coefficient A) − (Ne × coefficient C)} / V2 × coefficient B (5)
In the above equation (5), the air amount Qa and the engine rotational speed Ne sucked from the air cleaner 13 can be measured by the AFM 5 and the crank angle sensor 33, respectively, as described above, and the volume V1 of the intake passage 20 and the intake passage 21 The volume V2 and each coefficient can be obtained in advance. Therefore, the downstream pressure P2 can be obtained by calculation by substituting each value into the equation (5).
[0039]
When the upstream pressure P1 and the downstream pressure P2 are estimated as described above, the process proceeds to step S107, and the bypass valve 3 is changed from the closed state to the open state based on the pressures P1 and P2 obtained in the above-described steps. The upstream pressure Pt1 and the downstream pressure Pt2 after the required time (operation time) T (s) are obtained. This is because the operation time T (s) is required until the bypass valve 3 is completely opened from the closed state, and the pressure changes during this time. Note that the operating time T (s) is previously determined by experiments or the like.
[0040]
A specific calculation method is as a subroutine shown in FIG.
[0041]
In step S300, the increase amounts ΔP1 and ΔP2 per unit time are calculated for the upstream pressure P1 and the downstream pressure P2 from the previous calculated value and the current calculated value. When the predicted pressure pressures Pt1 and Pt2 after the operation time T (s) are expressed using the increase amounts ΔP1 and ΔP2, equations (6) and (7) are obtained.
[0042]
Pt1 = ΔP1 × T + P1 (6)
Pt2 = ΔP2 × T + P2 (7)
ΔP1, ΔP2: Pressure increase amount per unit time during the operation time T (s) In step S301, in order to more accurately determine the upstream and downstream pressures after the operation time T (s), FIG. The correction value hosei1 of the increase amount ΔP1 and the correction value hosei2 of the increase amount ΔP2 are obtained using the table and map shown in FIG.
FIG. 5 is a table in which the correction value “hosei1” is assigned to the engine rotation speed. The correction value “hosei1” increases to approach 1 as the engine speed of the engine 12 increases in the low rotation range, and approaches 1 in the intermediate range regardless of the rotation speed. 1 and decreases as the rotation speed increases in the high rotation range. The correction value hose1 is obtained by searching from this table according to the engine speed.
[0043]
FIG. 6 is a three-dimensional map in which the drive motor rotational speed is added as a variable to the table of FIG. 5. When the hosei2 increases and approaches 1 and both are in the intermediate range, the value is 1 regardless of the rotation speed. When both or either one is in the high rotation area, the correction value hosei2 decreases as the rotation speed increases. The correction value hosei2 is obtained by searching from this map according to the engine rotation speed and the drive motor rotation speed.
[0044]
In step S302, the increments ΔP1 and ΔP2 are corrected by using the correction values hosei1 and hosei2 obtained above to obtain ΔP1h and ΔP2h.
ΔP1h = ΔP1 × hosei1 (8)
ΔP2h = ΔP2 × hosei2 (9)
In step S303, the upstream and downstream predicted pressures Pt1 and Pt2 after the operation time T (s) are calculated using the corrected increments ΔP1h and ΔP2h as in the following equations (10) and (11).
[0045]
Pt1 = ΔP1h × T + P1 (10)
Pt2 = ΔP2h × T + P2 (11)
Next, returning to the flowchart of FIG.
[0046]
In step S108, the predicted pressures Pt1 and Pt2 obtained as described above are compared. When the upstream predicted pressure Pt1 becomes equal to or higher than the downstream predicted pressure Pt2, the process proceeds to step S109, the bypass valve 3 is opened, and the upstream side If the predicted pressure Pt1 is smaller than the downstream predicted pressure Pt2, the process returns to step S106.
[0047]
Here, the reason why the predicted pressures Pt1 and Pt2 are used for determining whether or not to open the valve will be described. When the bypass valve 3 is opened after the upstream pressure P1 and the downstream pressure P2 of the bypass valve 3 are equal, the intake passage cross-sectional area is reduced by the bypass valve 3 until the bypass valve 3 is completely opened. The side pressure P1 continues to rise and becomes higher than the downstream pressure P2. That is, the bypass valve 3 becomes an intake resistance, and the required amount of air is not supplied to the engine 12.
[0048]
Therefore, in order to make the upstream and downstream pressures of the bypass valve 3 equal when the bypass valve 3 is fully opened, the predicted pressure Pt1 considering the pressure rise during the operation time T (s) of the bypass valve 3 , Pt2.
[0049]
As described above, in the present embodiment, the upstream pressure P1 is detected by the pressure sensor 8, the downstream pressure P2 is estimated using the upstream pressure P1, and based on these, the predicted pressure after the operation time of the bypass valve 3 is estimated. Pt1 and Pt2 are calculated, and a valve opening command is issued to the bypass valve 3 when the predicted pressures Pt1 and Pt2 become equal.
[0050]
As described above, in the present embodiment, when the bypass valve 3 is fully opened, the valve opening operation of the bypass valve 3 is started at the timing when the pressures P1 and P2 on the upstream and downstream sides of the bypass valve 3 and the electric supercharger 2 become equal. Therefore, even if the bypass valve 3 is opened and closed, air does not flow through the bypass passage 7, thereby preventing occurrence of engine output torque shock.
[0051]
Since the downstream pressure P2 of the bypass valve 3 and the electric supercharger 2 is estimated based on the bypass valve upstream pressure P1 detected by the pressure sensor 8, the engine speed and the intake air amount, the downstream pressure P2 is measured. The cost can be reduced as compared with the case where a separate pressure sensor is installed, and the pressure can be estimated more accurately than when the upstream and downstream pressure sensors are estimated without being installed.
[0052]
A similar effect can be obtained by a method in which the pressure sensor 8 is provided on the downstream side to detect the downstream pressure P2, and the upstream pressure P1 is estimated based on the detected P2. In this case, the upstream pressure P1 is obtained as follows.
[0053]
The downstream pressure P2 detected by the pressure sensor 8 can be expressed as in Expression (12).
[0054]
P2 = (Qs−Qe) / V2 × coefficient B (12)
By transforming this, Qs = Qe + (P2 × V2) / coefficient B (13)
And Here, since Qe = Ne (engine speed) × coefficient C, Qs can be expressed by the following equation (13).
[0055]
Qs = (Ne × C) + (P2 × V2) / coefficient B (14)
Then, by substituting Equation (3) and Equation (14) into Equation (1), the upstream pressure P1 can be expressed as Equation (15).
[0056]
P1 = {Qa− (P2 × V2) / coefficient B− (Ne × coefficient C)} / V1 × coefficient A
... (15)
Here, it will be described which of the upstream and downstream pressure sensors 8 should be installed.
[0057]
Regardless of whether the pressure sensor 8 is installed on the upstream or downstream side of the bypass valve 3, the detected one pressure value is used to obtain the air amount Qs passing through the electric supercharger 2, and the other air amount is determined from this air amount Qs. The pressure value is estimated.
[0058]
However, when installed on the upstream side, the air amount Qs is expressed as shown in Equation (2), and when installed on the downstream side, the air amount Qs is expressed as shown in Equation (13).
[0059]
Qs = Qa− (P1 × V1) / coefficient A (2)
Qs = Qe + (P2 × V2) / coefficient B (13)
That is, the accuracy of the air amount Qs passing through the electric supercharger 2 depends on the accuracy of the intake air amount Qa measured by the air flow meter 5 when the pressure sensor 8 is installed on the upstream side, and is installed on the downstream side. Depends on the accuracy of the air amount Qe calculated from the engine rotational speed Ne. If the value directly measured by the air flow meter 5 is compared with the value obtained by calculation using the engine rotational speed Ne detected by the crank angle sensor 33, the value directly measured by the air flow meter 5 is considered to have higher accuracy. Therefore, it is considered that the pressure sensor 8 can be estimated with higher accuracy if it is provided on the upstream side.
[0060]
When the pressure sensor 8 is installed on the upstream side, the pressure of the air compressed by the turbocharger 1 is measured, whereas when the pressure sensor 8 is installed on the downstream side, the turbocharger is measured. The pressure of the air compressed by the electric supercharger 2 after being compressed by the machine 1 is measured, and the influence of the temperature rise due to the compression becomes large. From this, it is considered that the pressure sensor 8 can be estimated with higher accuracy if it is installed on the upstream side.
[0061]
The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.
[Brief description of the drawings]
FIG. 1 is a diagram showing a system configuration according to an embodiment of the present invention.
FIG. 2 is a flowchart of bypass valve control executed by the ECM.
FIG. 3 is a flowchart of a subroutine for estimating a downstream pressure from a detection value of a pressure sensor installed on the upstream side.
FIG. 4 is a flowchart for estimating the pressure in the intake passage in consideration of the pressure increase during the opening operation of the bypass valve.
FIG. 5 is a table in which a correction value of a pressure increase gradient during operation of a bypass valve is assigned to an engine speed.
FIG. 6 is a three-dimensional map in which a correction value of a pressure increase gradient during operation of a bypass valve is assigned to an engine speed and a motor rotation speed.
[Explanation of symbols]
1 Turbocharger 2 Electric supercharger 2a Compressor 2b Drive motor 2c Shaft 3 Bypass valve 4 Control unit (ECM)
5 Air flow meter (AFM)
6 Intake passage 7 Bypass passage 8 Pressure sensor 11 Rotational speed sensor 12 Engine 13 Air cleaner 20 Intake passage (upstream side)
21 Intake passage (downstream)
31 Throttle valve

Claims (4)

エンジンの排気ガス圧力によって駆動するターボ過給機と、
電動機によって駆動する電動過給機と、
前記電動過給機を迂回して前記電動過給機の上流と下流の吸気通路をつなぐバイパス通路と、
前記バイパス通路を開閉するバイパス弁と、
前記バイパス弁の上下流のいずれか一方の吸気通路に設けた圧力検出手段と、
前記圧力検出手段による検出値と吸入空気量とエンジン回転速度とから前記バイパス弁の上下流のいずれか他方の吸気通路の圧力を推定する圧力推定手段と、
車両の加速要求を検出する手段と、
前記加速要求を検出したときに前記バイパス弁と関連付けながら前記電動過給機による過給を行うとともに、前記バイパス弁の上下流の圧力がほぼ等しくなったときに前記バイパス弁を開弁する制御手段と、を備えることを特徴とする電動過給機構のバイパス弁制御装置。
A turbocharger driven by the exhaust gas pressure of the engine;
An electric supercharger driven by an electric motor;
A bypass passage that bypasses the electric supercharger and connects an intake passage upstream and downstream of the electric supercharger;
A bypass valve for opening and closing the bypass passage;
Pressure detecting means provided in one intake passage upstream or downstream of the bypass valve;
Pressure estimation means for estimating the pressure of the other intake passage upstream or downstream of the bypass valve from the detection value by the pressure detection means, the intake air amount, and the engine rotation speed;
Means for detecting a vehicle acceleration request;
Control means for performing supercharging by the electric supercharger in association with the bypass valve when detecting the acceleration request, and opening the bypass valve when the upstream and downstream pressures of the bypass valve become substantially equal And a bypass valve control device for an electric supercharging mechanism.
前記制御手段は、前記圧力検出手段による検出値と前記圧力推定手段による推定値とから、前記バイパス弁の開弁動作時間後の上下流の圧力を予測し、上下流の予測圧力がほぼ等しくなったときに開弁指令を出す請求項1に記載の電動過給機構のバイパス弁制御手段。The control means predicts upstream and downstream pressures after the valve opening operation time of the bypass valve from the detected value by the pressure detecting means and the estimated value by the pressure estimating means, and the predicted upstream and downstream pressures are substantially equal. The bypass valve control means of the electric supercharging mechanism according to claim 1, wherein a valve opening command is issued when 前記上流側の予測圧力はエンジンの回転速度に基いて、前記下流側の予測圧力はエンジンの回転速度と電動機の回転速度とに基いて、それぞれ補正を行う請求項2に記載の電動過給機構のバイパス弁制御装置。3. The electric supercharging mechanism according to claim 2, wherein the upstream-side predicted pressure is corrected based on an engine rotational speed, and the downstream-side predicted pressure is corrected based on an engine rotational speed and an electric motor rotational speed. Bypass valve control device. 前記圧力検出手段は、前記バイパス弁の上流の吸気通路に設ける請求項1から3のいずれか一つに記載の電動過給機構のバイパス弁制御装置。4. The bypass valve control device for an electric supercharging mechanism according to claim 1, wherein the pressure detection means is provided in an intake passage upstream of the bypass valve. 5.
JP2003199820A 2003-07-22 2003-07-22 Bypass valve control device for electric supercharging mechanism Expired - Fee Related JP3846462B2 (en)

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US9534532B2 (en) 2011-09-30 2017-01-03 Eaton Corporation Supercharger assembly with two rotor sets
US9534531B2 (en) 2011-09-30 2017-01-03 Eaton Corporation Supercharger assembly for regeneration of throttling losses and method of control
WO2013049438A2 (en) 2011-09-30 2013-04-04 Eaton Corporation Supercharger assembly with independent superchargers and motor/generator
EP2831389B1 (en) 2012-03-29 2016-09-14 Eaton Corporation Variable speed hybrid electric supercharger assembly and method of control of vehicle having same
WO2014165233A1 (en) 2013-03-12 2014-10-09 Eaton Corporation Adaptive state of charge regulation and control of variable speed hybrid electric supercharger assembly for efficient vehicle operation
JP6413661B2 (en) * 2014-11-06 2018-10-31 株式会社豊田自動織機 Intake bypass control method for internal combustion engine and intake bypass control system for internal combustion engine
JP5924716B1 (en) * 2015-02-03 2016-05-25 三菱電機株式会社 Control device for internal combustion engine

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