JP4158670B2 - Control device for spark ignition engine - Google Patents

Control device for spark ignition engine Download PDF

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JP4158670B2
JP4158670B2 JP2003339992A JP2003339992A JP4158670B2 JP 4158670 B2 JP4158670 B2 JP 4158670B2 JP 2003339992 A JP2003339992 A JP 2003339992A JP 2003339992 A JP2003339992 A JP 2003339992A JP 4158670 B2 JP4158670 B2 JP 4158670B2
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cylinder
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fuel ratio
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JP2005105937A (en
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敏朗 西本
弘和 松浦
洋 稲富
啓二 荒木
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Mazda Motor Corp
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Description

本発明は、各気筒の燃焼サイクルが所定の位相差をもつように設定された多気筒の火花点火式エンジンの制御装置に関するものである。   The present invention relates to a control device for a multi-cylinder spark ignition engine in which the combustion cycle of each cylinder is set to have a predetermined phase difference.

従来から、火花点火式エンジンにおいて、各気筒内の混合気の空燃比を理論空燃比よりも大きいリーン空燃比とした状態で燃焼を行わせることにより燃費の改善を図る技術が知られており、燃焼室内に直接燃料を噴射する燃料噴射弁を備え、低負荷低回転領域等で上記燃料噴射弁から圧縮行程で燃料を噴射して成層燃焼を行わせることにより、超リーン燃焼を実現するようにしたものが知られている（例えば、特許文献１参照）。   Conventionally, in a spark ignition type engine, a technique for improving fuel consumption by performing combustion in a state where the air-fuel ratio of the air-fuel mixture in each cylinder is set to a lean air-fuel ratio larger than the stoichiometric air-fuel ratio is known, A fuel injection valve for directly injecting fuel into the combustion chamber is provided, and super lean combustion is realized by injecting fuel in the compression stroke from the fuel injection valve in the low-load low-rotation region or the like to cause stratified combustion. Is known (for example, see Patent Document 1).

このようなエンジンにおいては、排気ガス浄化用の触媒として通常の三元触媒（ＨＣ，ＣＯおよびＮＯｘに対して理論空燃比付近で浄化性能の高い触媒）だけではリーン運転時にＮＯｘを充分に浄化することができないため、特許文献１にも示されるように、酸素過剰雰囲気でＮＯｘを吸着して酸素濃度低下雰囲気でＮＯｘの離脱、還元を行うリーンＮＯｘ触媒を設けている。そして、このようなリーンＮＯｘ触媒を用いる場合、リーン運転中にリーンＮＯｘ触媒のＮＯｘ吸着量が増大したときは、例えば特許文献１に示されるように、主燃焼用以外に追加燃料を膨張行程中で噴射することにより、排気ガスの空燃比をリッチ化するとともに、ＣＯを生成してＮＯｘの離脱、還元を促進するようにしている。
特開平１０−２９８３６号公報 In such an engine, an ordinary three-way catalyst (a catalyst having a high purification performance near the theoretical air-fuel ratio with respect to HC, CO and NOx) as an exhaust gas purification catalyst sufficiently purifies NOx during lean operation. Therefore, as shown in Patent Document 1, there is provided a lean NOx catalyst that adsorbs NOx in an oxygen-excess atmosphere and releases and reduces NOx in an oxygen concentration-reduced atmosphere. When such a lean NOx catalyst is used, if the NOx adsorption amount of the lean NOx catalyst increases during the lean operation, for example, as shown in Patent Document 1, additional fuel is being expanded during the expansion stroke other than for main combustion. In this way, the air-fuel ratio of the exhaust gas is enriched, and CO is generated to promote the separation and reduction of NOx.
Japanese Patent Laid-Open No. 10-29836

上記のような従来のリーン運転を行うエンジンでは、リーン運転中のＮＯｘ浄化性能を確保するために、高価なリーンＮＯｘ触媒を排気通路に設ける必要があり、コスト的に不利である。また、上記リーンＮＯｘ触媒の浄化性能を維持するためには、上述のようにＮＯｘ吸着量の増大時に、ＮＯｘを離脱、還元させるために追加燃料の供給等による一時的な空燃比のリッチ化を行う必要がある。さらに、使用燃料が硫黄分を多く含む場合には、上記リーンＮＯｘ触媒の硫黄被毒を解消するための触媒の加熱処理および還元材供給等のリジェネレーション処理が必要となり、これらによって燃費の改善効果が低下する。   In an engine that performs the conventional lean operation as described above, it is necessary to provide an expensive lean NOx catalyst in the exhaust passage in order to ensure NOx purification performance during the lean operation, which is disadvantageous in terms of cost. Further, in order to maintain the purification performance of the lean NOx catalyst, as described above, when the NOx adsorption amount increases, temporary enrichment of the air-fuel ratio by supplying additional fuel or the like to release and reduce NOx is performed. There is a need to do. Furthermore, when the fuel used contains a large amount of sulfur, it is necessary to perform regeneration processing such as catalyst heating treatment and reducing material supply to eliminate sulfur poisoning of the lean NOx catalyst. Decreases.

また、燃費改善のための別の手法として、圧縮自己着火が研究されており、この圧縮自己着火は、ディーゼルエンジンと同様に圧縮行程終期に燃焼室内を高温・高圧にして燃料を自己着火させるものであり、空燃比が超リーンの状態や多量のＥＧＲが導入されている状態でも、このような圧縮自己着火が行われれば燃焼室全体が一気に燃焼するため、仕事に寄与しない遅い燃焼が避けられて燃費改善に有利となる。   As another method for improving fuel efficiency, compression self-ignition has been studied. This compression self-ignition, like a diesel engine, causes the combustion chamber to self-ignite at a high temperature and high pressure at the end of the compression stroke. Even if the air-fuel ratio is extremely lean or a large amount of EGR is introduced, if such compression self-ignition is performed, the entire combustion chamber burns at once, so that slow combustion that does not contribute to work can be avoided. This is advantageous for improving fuel economy.

しかし、通常の火花点火式ガソリンエンジンでは、燃焼のために強制点火が必要であって、圧縮上死点付近で燃焼室内の温度、圧力が圧縮自己着火を生じさせ得る程度までには高められず、圧縮自己着火を行わせるには燃焼室内の温度または圧力を大幅に高めるための格別の工夫が必要となるが、従来、高負荷領域でのノッキング（燃焼室内で火炎が伝播する前に混合気が自然着火することによる異常燃焼）を避けつつ、燃費改善が要求される部分負荷領域で圧縮自己着火を生じさせる程度まで燃焼室内の温度または圧力を高めることが困難であった。   However, in a normal spark-ignition gasoline engine, forced ignition is required for combustion, and the temperature and pressure in the combustion chamber cannot be increased to the extent that compression self-ignition can occur near the compression top dead center. However, in order to perform compression self-ignition, special measures are required to greatly increase the temperature or pressure in the combustion chamber. Conventionally, however, knocking in a high load region (mixture before the flame propagates in the combustion chamber) However, it is difficult to increase the temperature or pressure in the combustion chamber to such an extent that compression self-ignition occurs in a partial load region where fuel consumption improvement is required, while avoiding abnormal combustion due to spontaneous ignition).

そこで、本出願人は、リーン燃焼と圧縮自己着火とを併用して大幅な燃費の改善効果をもたせるべく、エンジンの部分負荷領域で、排気行程と吸気行程が重なる一対の気筒間において排気行程にある先行気筒から排出される既燃ガスがそのまま吸気行程にある後続気筒に気筒間ガス通路を介して導入される２気筒接続状態とするとともに、先行気筒では、空燃比を理論空燃比よりも大きいリーン空燃比に設定して強制点火により燃焼を行わせ、後続気筒では、先行気筒から導入されたリーン空燃比の既燃ガスに燃料を供給して圧縮自己着火により燃焼を行わせるようにした火花点火式エンジンの制御装置に関する技術を出願している（特願２００２−１８５２４２号）。   Therefore, in order to achieve a significant fuel economy improvement effect by using both lean combustion and compression self-ignition, the applicant of the present invention has an exhaust stroke between a pair of cylinders in which the exhaust stroke and the intake stroke overlap in a partial load region of the engine. The burned gas discharged from a certain preceding cylinder is directly connected to the succeeding cylinder in the intake stroke via the inter-cylinder gas passage, and the air-fuel ratio is larger than the stoichiometric air-fuel ratio in the preceding cylinder. A spark that is set to a lean air-fuel ratio to cause combustion by forced ignition, and in the subsequent cylinder, fuel is supplied to the burned gas having a lean air-fuel ratio introduced from the preceding cylinder and combustion is performed by compression self-ignition. A technology relating to a control device for an ignition engine has been filed (Japanese Patent Application No. 2002-185242).

上記のようにエンジンの部分負荷領域で特殊運転モードの制御状態とすることにより、先行気筒では、リーン空燃比での燃焼が行われて熱効率が高められるとともに、ポンピングロスが低減されるため、大幅な燃費の改善効果が得られ、かつ後続気筒では、先行気筒から導入されたリーン空燃比の既燃ガスと新たに供給された燃料とによって空燃比が理論空燃比に設定された状態で燃焼が行われることにより、ポンピングロスによる燃費の改善効果が得られる。また、先行気筒から気筒間ガス通路を介して後続気筒に高温の既燃ガスが導入されるため、圧縮行程で自己着火が可能な状態まで燃焼室内の温度が上昇して圧縮自己着火が行われることにより、大幅な燃費の改善効果とＮＯｘの発生抑制効果とが得られ、しかも後続気筒からは理論空燃比で燃焼した既燃ガスのみが排出されるため、リーンＮＯｘ触媒を排気通路に設けることなく、三元触媒だけで排気の浄化性能が確保される。   By setting the control state of the special operation mode in the partial load region of the engine as described above, in the preceding cylinder, combustion at a lean air-fuel ratio is performed to increase the thermal efficiency, and the pumping loss is reduced. In the succeeding cylinder, combustion is performed in a state where the air-fuel ratio is set to the stoichiometric air-fuel ratio by the lean air-fuel ratio burned gas introduced from the preceding cylinder and the newly supplied fuel. By doing so, the effect of improving the fuel consumption due to the pumping loss can be obtained. In addition, since high-temperature burned gas is introduced from the preceding cylinder to the succeeding cylinder via the inter-cylinder gas passage, the temperature in the combustion chamber rises to a state where self-ignition is possible in the compression stroke, and compression self-ignition is performed. As a result, a significant fuel economy improvement effect and NOx generation suppression effect can be obtained, and since only the burned gas burned at the stoichiometric air-fuel ratio is discharged from the subsequent cylinder, a lean NOx catalyst is provided in the exhaust passage. In addition, exhaust purification performance is ensured with only a three-way catalyst.

ところで、上記のようにエンジンの運転状態に応じて各気筒独立状態で燃焼が行われる通常運転モードと、先行気筒から排出される既燃ガスをそのまま後続気筒に導入させる２気筒接続状態で燃焼が行われる特殊運転モードとに制御状態が切り換えられるエンジンでは、上記各気筒独立状態と２気筒接続状態との間でガス流通経路を切り換えるタイミングが問題となり、この切換過渡期にエミッション性能が低下したり、トルクショックが発生したりする等の弊害を生じることなく、上記ガス流通経路の切換を適正に実行することが望まれる。   By the way, as described above, combustion is performed in a normal operation mode in which combustion is performed in an independent state of each cylinder according to the operating state of the engine, and in a two-cylinder connection state in which burned gas discharged from the preceding cylinder is directly introduced into the succeeding cylinder. In an engine in which the control state is switched to the special operation mode to be performed, there is a problem in the timing of switching the gas flow path between each cylinder independent state and the two-cylinder connected state, and the emission performance decreases during this switching transition period. It is desirable to appropriately perform the switching of the gas flow path without causing adverse effects such as occurrence of torque shock.

本発明は、このような技術に基づき、ガス流通経路の切換過渡期におけるエミッション性能の低下やトルクショックの発生等を防止しつつ、各気筒独立状態と２気筒接続状態との間でガス流通経路を適正に切り換えることができる火花点火式エンジンの制御装置を提供するものである。   The present invention is based on such a technique, and prevents gas flow paths between the cylinder independent state and the two-cylinder connected state while preventing a reduction in emission performance, generation of torque shock, and the like in the transition period of the gas flow path. It is intended to provide a spark ignition engine control device capable of appropriately switching the engine.

請求項１に係る発明は、各気筒の燃焼サイクルが所定の位相差をもつように設定され、各気筒にそれぞれ新気を導入させて各気筒を独立状態で燃焼させる通常運転モードの制御と、エンジンの低回転低負荷領域で、排気行程と吸気行程が重なる一対の気筒間において排気行程にある先行気筒から排出される既燃ガスがそのまま吸気行程にある後続気筒に気筒間ガス通路を介して導入され、この後続気筒から排出されるガスが三元触媒を備えた排気通路に導かれるような２気筒接続状態としつつ、先行気筒の空燃比を理論空燃比よりも大きいリーン空燃比として燃焼を行わせ、この先行気筒から後続気筒にリーン空燃比の既燃ガスを導入させて後続気筒の空燃比を理論空燃比とするように新たに供給された燃料とともに燃焼させる特殊運転モードの制御とを実行する運転モード制御手段を備えた多気筒の火花式点火エンジンにおいて、上記通常運転モードの各気筒独立状態と特殊運転モードの２気筒接続状態との間でガス流通経路を切り換える際に、後続気筒に対する燃料供給を停止するとともに、先行気筒の空燃比が理論空燃比となるように先行気筒に対してのみ燃料供給を行って先行気筒のみを燃焼させる過渡運転モードを介在させて上記ガス流通経路の切換を行うものである。 The invention according to claim 1 is a control of a normal operation mode in which the combustion cycle of each cylinder is set to have a predetermined phase difference , each cylinder is introduced with fresh air, and each cylinder is burned independently. The burned gas discharged from the preceding cylinder in the exhaust stroke between a pair of cylinders in which the exhaust stroke and the intake stroke overlap in the low rotation and low load region of the engine is directly passed through the inter-cylinder gas passage to the subsequent cylinder in the intake stroke. The combustion is performed with the air-fuel ratio of the preceding cylinder being a lean air-fuel ratio larger than the stoichiometric air-fuel ratio while the two-cylinder connection state is established in which the gas discharged from the succeeding cylinder is introduced into the exhaust passage provided with the three-way catalyst. done so, special operation mode to burn with freshly supplied fuel to the management Ronsora-fuel ratio of the following cylinders by introducing burned gas of a lean air-fuel ratio in the following cylinders from the preceding cylinders A multi-cylinder spark-ignition engine having the operation mode control means for performing control of, when switching the gas flow path between the two-cylinder connection state of each cylinder independently state and the special operation mode of the normal operation mode In addition, the fuel supply to the succeeding cylinder is stopped, and the transient operation mode in which only the preceding cylinder is burned by supplying the fuel only to the preceding cylinder so that the air-fuel ratio of the preceding cylinder becomes the stoichiometric air-fuel ratio is interposed. The gas distribution path is switched.

また、請求項２に係る発明は、上記請求項１に記載の火花点火式エンジンの制御装置において、気筒間ガス通路に設けられた開閉弁を作動状態と停止状態に切り換えるように制御する制御部材と、先行気筒に設けられた排気弁の作動状態と停止状態とに切り換えるように制御する制御部材とを別々に設け、特殊運転モードの２気筒接続状態から通常運転モードの各気筒独立状態にガス流通経路の切換を行う際には、気筒間ガス通路の開閉弁を停止状態とする前に先行気筒の排気弁を作動状態とし、通常運転モードの各気筒独立状態から特殊運転モードの２気筒接続状態にガス流通経路の切換を行う際には、先行気筒の排気弁を停止状態とする前に気筒間ガス通路の開閉弁を作動状態とするものである。 Further, the invention according to claim 2 is the control device for controlling the spark ignition engine according to claim 1 , wherein the on-off valve provided in the inter-cylinder gas passage is controlled to be switched between the operating state and the stopped state. And a control member that controls to switch between the operating state and the stopped state of the exhaust valve provided in the preceding cylinder are provided separately, and gas is supplied from the two-cylinder connection state in the special operation mode to the individual cylinder independent state in the normal operation mode. When switching the flow path, the exhaust valve of the preceding cylinder is activated before the on-off valve of the inter-cylinder gas passage is stopped, and each cylinder independent state in the normal operation mode is connected to the two cylinders in the special operation mode. When switching the gas flow path to the state, the on-off valve of the inter-cylinder gas passage is activated before the exhaust valve of the preceding cylinder is stopped.

また、請求項３に係る発明は、上記請求項２に記載の火花点火式エンジンの制御装置において、各気筒に設けられた吸気弁および排気弁の動弁機構に、各弁を作動状態と停止状態とに変化させてガス流通経路を切り換える切換機構を設けるとともに、この切換機構に対する油圧の給排を制御することにより上記各弁を作動状態と停止状態とに変化させる複数の制御部材を設け、この制御部材による上記切換機構の動作開始時期に時間差をもたせたものである。 The invention according to claim 3, in the control apparatus for a spark-ignited internal combustion engine according to the claim 2, the valve mechanism of the intake valve and an exhaust valve provided in each cylinder, and each valve operating state STOP Provided with a switching mechanism that changes the gas flow path by changing to a state, and provided with a plurality of control members that change the respective valves between an operating state and a stopped state by controlling the supply and discharge of hydraulic pressure to the switching mechanism, A time difference is given to the operation start timing of the switching mechanism by the control member.

請求項１に係る発明では、エンジンの低回転低負荷領域において上記特殊運転モードの燃焼制御が実行されることにより、上記先行気筒ではリーン燃焼による熱効率向上およびポンピングロス低減による燃費改善効果が得られ、かつ上記後続気筒では先行気筒から導入されたリーン空燃比の既燃ガスとともに新たに供給された燃料が燃焼するために、少なくともポンピングロス低減による燃費効果は得られる。また、先行気筒では大幅なリーン空燃比で燃焼が行われることによりＮＯｘ発生量が比較的少なく抑えられ、後続気筒では、先行気筒から既燃ガスが導入されることで多量のＥＧＲが行われているのと同等の状態となることからＮＯｘの発生が充分に抑制され、エミッション性能の向上に有利となる。そして、上記通常運転モードの各気筒独立状態と特殊運転モードの２気筒接続状態との間でガス流通経路の切換が先行気筒のみを燃焼させる過渡運転モードを介して行われるため、ガス流通経路の切換過渡期にエミッション性能が低下したり、トルクショックが発生したりする等の問題を生じることなく、上記ガス流通経路の切換を適正に実行することができる。また、排気通路に単一の三元触媒が設けられたエンジンにおいて、上記通常運転モードの各気筒独立状態と特殊運転モードの２気筒接続状態との間でガス流通経路の切換を行う際に、先行気筒の空燃比を理論空燃比として先行気筒のみを燃焼させる過渡運転モードを介在させるようにしたため、この先行気筒から排気通路に導出された排気ガスを上記三元触媒により効果的に浄化することができ、簡単な構成でエミッション性能を確保できるという利点がある。 In the invention according to claim 1, by performing the combustion control in the special operation mode in the low rotation and low load region of the engine, the preceding cylinder can obtain the fuel efficiency improvement effect by improving the thermal efficiency by lean combustion and reducing the pumping loss. In addition, since the newly supplied fuel burns together with the burned gas having a lean air-fuel ratio introduced from the preceding cylinder in the succeeding cylinder, at least the fuel consumption effect by reducing the pumping loss can be obtained. Further, the preceding cylinder performs combustion at a large lean air-fuel ratio, so that the amount of NOx generated is suppressed to be relatively small. In the succeeding cylinder, a large amount of EGR is performed by introducing burned gas from the preceding cylinder. Therefore, the generation of NOx is sufficiently suppressed, which is advantageous for improving the emission performance. Since the gas flow path is switched between the cylinder independent state in the normal operation mode and the 2-cylinder connected state in the special operation mode through the transient operation mode in which only the preceding cylinder is burned, It is possible to appropriately perform the switching of the gas flow path without causing problems such as a decrease in emission performance or occurrence of torque shock during the switching transition period. Further, in an engine provided with a single three-way catalyst in the exhaust passage, when switching the gas flow path between each cylinder independent state in the normal operation mode and the two-cylinder connection state in the special operation mode, Since the transient operation mode in which only the preceding cylinder is burned is made with the air-fuel ratio of the preceding cylinder as the stoichiometric air-fuel ratio, the exhaust gas led out from the preceding cylinder to the exhaust passage is effectively purified by the three-way catalyst. There is an advantage that emission performance can be secured with a simple configuration.

請求項２に係る発明では、上記特殊運転モードの２気筒接続状態から通常運転モードの各気筒独立状態にガス流通経路を切り換える際に、気筒間ガス通路の開閉弁を停止状態とする前に先行気筒の排気弁の作動状態とするようにしたため、先行気筒の排気性を確保してその燃焼を確実に行わせることができる。また、上記通常運転モードの各気筒独立状態から特殊運転モードの２気筒接続状態にガス流通経路を切り換える際には、先行気筒の排気弁を停止状態とする前に、気筒間ガス通路の開閉弁を作動状態とするように構成したため、先行気筒の排気性を確保してその燃焼を確実に行わせることができる。 In the invention according to claim 2 , when the gas flow path is switched from the two-cylinder connected state in the special operation mode to the individual cylinder independent state in the normal operation mode, it is preceded before the on-off valve of the inter-cylinder gas passage is stopped. Since the operation state of the exhaust valve of the cylinder is set, the exhaust performance of the preceding cylinder can be secured and the combustion can be performed reliably. When switching the gas flow path from the cylinder independent state in the normal operation mode to the 2-cylinder connection state in the special operation mode, the on-off valve of the inter-cylinder gas passage is set before the exhaust valve of the preceding cylinder is stopped. Since the engine is configured to be in an operating state, the exhaust performance of the preceding cylinder can be secured and the combustion can be performed reliably.

請求項３に係る発明では、上記各弁の動弁機構に設けられた切換機構に対する作動油の給排を制御して各弁を作動状態と停止状態とに変化させることにより、特殊運転モードの２気筒接続状態と通常運転モードの各気筒独立状態との間でガス流通経路を切り換える際に、上記切換機構の動作開始時期に時間差をもたせるように構成したため、上記切換機構に供給される作動油圧の上昇遅れが生じるのを効果的に防止し、先行気筒の排気性が損なわれるようなガス流通経路が形成されるという事態の発生を効果的に防止できるという利点がある。 In the invention according to claim 3 , by controlling the supply and discharge of the hydraulic oil to and from the switching mechanism provided in the valve operating mechanism of each valve and changing each valve between the operating state and the stopped state, When the gas flow path is switched between the two-cylinder connected state and each cylinder independent state in the normal operation mode, a time difference is provided in the operation start timing of the switching mechanism. There is an advantage that it is possible to effectively prevent the occurrence of a delay in the rise of the cylinder and effectively prevent the occurrence of a situation in which a gas flow path is formed that impairs the exhaust performance of the preceding cylinder.

図１は、本発明が適用されるエンジンの概略構成を示し、図２はエンジン本体１の一つの気筒とそれに対して設けられた吸・排気弁等の構造を概略的に示している。これらの図において、エンジン本体１は複数の気筒を有し、図示の実施形態では４つの気筒２Ａ〜２Ｄを有している。各気筒２Ａ〜２Ｄにはピストン３が嵌挿され、ピストン３の上方に燃焼室４が形成されている。各気筒２Ａ〜２Ｄの燃焼室４の頂部には点火プラグ７が装備され、そのプラグ先端が燃焼室４内に臨んでいる。この点火プラグ７には、電子制御による点火時期のコントロールが可能な点火回路８が接続されている。   FIG. 1 shows a schematic configuration of an engine to which the present invention is applied, and FIG. 2 schematically shows a structure of one cylinder of an engine body 1 and intake / exhaust valves provided for the cylinder. In these drawings, the engine body 1 has a plurality of cylinders, and in the illustrated embodiment, has four cylinders 2A to 2D. A piston 3 is fitted into each of the cylinders 2 </ b> A to 2 </ b> D, and a combustion chamber 4 is formed above the piston 3. A spark plug 7 is provided at the top of the combustion chamber 4 of each cylinder 2 </ b> A to 2 </ b> D, and the tip of the plug faces the combustion chamber 4. An ignition circuit 8 capable of controlling the ignition timing by electronic control is connected to the spark plug 7.

燃焼室４の側方部には、燃焼室４内に燃料を直接噴射する燃料噴射弁９が設けられている。この燃料噴射弁９は、図略のニードル弁およびソレノイドを内蔵し、パルス信号が入力されることにより、そのパルス入力時期にパルス幅に対応する時間だけ駆動されて開弁し、その開弁時間に応じた量の燃料を噴射するように構成されている。なお、この燃料噴射弁９には、図外の燃料ポンプにより燃料供給通路等を介して燃料が供給され、かつ圧縮行程における燃焼室４内の圧力よりも高い燃料圧力を与え得るように燃料供給系統が構成されている。   A fuel injection valve 9 that directly injects fuel into the combustion chamber 4 is provided at a side portion of the combustion chamber 4. The fuel injection valve 9 includes a needle valve and a solenoid (not shown). When a pulse signal is input, the fuel injection valve 9 is driven for a time corresponding to the pulse width at the pulse input timing to open the valve. It is comprised so that the quantity of fuel according to may be injected. The fuel injection valve 9 is supplied with fuel via a fuel supply passage or the like by a fuel pump (not shown) and is supplied with a fuel pressure higher than the pressure in the combustion chamber 4 during the compression stroke. A system is configured.

そして、各気筒２Ａ〜２Ｄが所定の位相差をもって吸気、圧縮、膨張および排気の各行程からなるサイクルを行うように構成されており、４気筒エンジンの場合、気筒列方向の一端側から１番気筒２Ａ、２番気筒２Ｂ、３番気筒２Ｃ、４番気筒２Ｄと呼ぶと、図３に示すように上記サイクルが１番気筒２Ａ、３番気筒２Ｃ、４番気筒２Ｄ、２番気筒２Ｂの順にクランク角で１８０°ずつの位相差をもって行われる。なお、図３において、ＥＸは排気行程、ＩＮは吸気行程であり、また、Ｆは燃料噴射、Ｓは強制点火を表し、図中の星マークは圧縮着火が行われることを表している。   Each of the cylinders 2A to 2D is configured to perform a cycle including intake, compression, expansion, and exhaust strokes with a predetermined phase difference. In the case of a four-cylinder engine, the cylinder is first from one end side in the cylinder row direction. When the cylinder 2A, the second cylinder 2B, the third cylinder 2C, and the fourth cylinder 2D are called, as shown in FIG. 3, the cycle is the same as that of the first cylinder 2A, the third cylinder 2C, the fourth cylinder 2D, and the second cylinder 2B. In sequence, the crank angle is performed with a phase difference of 180 °. In FIG. 3, EX is an exhaust stroke, IN is an intake stroke, F is fuel injection, S is forced ignition, and a star mark in the drawing indicates that compression ignition is performed.

排気行程と吸気行程が一致する一対の気筒間には、排気行程と吸気行程が一致して両行程がぴったりと重なるときの排気行程側の気筒（当明細書ではこれを先行気筒と呼ぶ）から、吸気行程側の気筒（当明細書ではこれを後続気筒と呼ぶ）に既燃ガスをそのまま導くことができるように、気筒間ガス通路２２が設けられている。当実施形態の４気筒エンジンでは、図３に示すように１番気筒２Ａの排気行程（ＥＸ）と２番気筒２Ｂの吸気行程（ＩＮ）とが重なり、また４番気筒２Ｄの排気行程（ＥＸ）と３番気筒２Ｃの吸気行程（ＩＮ）が重なるので、１番気筒２Ａと２番気筒２Ｂ、および、４番気筒２Ｄと３番気筒２Ｃがそれぞれ一対をなし、１番気筒２Ａおよび４番気筒２Ｄが先行気筒、２番気筒２Ｂおよび３番気筒２Ｃが後続気筒となる。   Between a pair of cylinders in which the exhaust stroke and the intake stroke coincide with each other, from the cylinder on the exhaust stroke side when the exhaust stroke and the intake stroke coincide with each other and exactly overlap each other (this is referred to as a preceding cylinder in this specification) An inter-cylinder gas passage 22 is provided so that the burned gas can be guided as it is to a cylinder on the intake stroke side (referred to as a subsequent cylinder in the present specification). In the four-cylinder engine of this embodiment, as shown in FIG. 3, the exhaust stroke (EX) of the first cylinder 2A and the intake stroke (IN) of the second cylinder 2B overlap, and the exhaust stroke (EX) of the fourth cylinder 2D. ) And the intake stroke (IN) of the third cylinder 2C overlap, so that the first cylinder 2A and the second cylinder 2B, and the fourth cylinder 2D and the third cylinder 2C form a pair, respectively, and the first cylinder 2A and the fourth cylinder The cylinder 2D is the preceding cylinder, the second cylinder 2B, and the third cylinder 2C are the subsequent cylinders.

各気筒の吸・排気ポートとこれに接続される吸気通路、排気通路および気筒間ガス通路は、具体的には次のように構成されている。先行気筒である１番気筒２Ａおよび４番気筒２Ｄには、それぞれ、新気を導入するための吸気ポート１１と、既燃ガス（排気ガス）を排気通路に送り出すための第１排気ポート１２ａと、既燃ガスを後続気筒に導出するための第２排気ポート１２ｂとが配設されている。また、後続気筒である２番気筒２Ｂおよび３番気筒２Ｃには、それぞれ、新気を導入するための第１吸気ポート１１ａと、先行気筒からの既燃ガスを導入するための第２吸気ポート１１ｂと、既燃ガスを排気通路に送り出すための排気ポート１２とが配設されている。   Specifically, the intake / exhaust port of each cylinder and the intake passage, exhaust passage, and inter-cylinder gas passage connected thereto are configured as follows. The first cylinder 2A and the fourth cylinder 2D, which are the preceding cylinders, respectively include an intake port 11 for introducing fresh air, and a first exhaust port 12a for sending burned gas (exhaust gas) to the exhaust passage. A second exhaust port 12b for leading the burned gas to the subsequent cylinder is provided. The second cylinder 2B and the third cylinder 2C, which are the subsequent cylinders, respectively, have a first intake port 11a for introducing fresh air and a second intake port for introducing burned gas from the preceding cylinder. 11b and an exhaust port 12 for sending burned gas to the exhaust passage.

図１に示す例では、先行気筒２Ａ，２Ｄにおける吸気ポート１１および後続気筒２Ｂ，２Ｃにおける第１吸気ポート１１ａが、１気筒当り２個ずつ、燃焼室の一方側部に並列的に設けられている。また、先行気筒２Ａ，２Ｄにおける第１排気ポート１２ａおよび第２排気ポート１２ｂならびに後続気筒２Ｂ，２Ｃにおける第２吸気ポート１１ｂおよび排気ポート１２が、燃焼室の他方側部に並列的に設けられている。   In the example shown in FIG. 1, two intake ports 11 for the preceding cylinders 2A and 2D and two first intake ports 11a for the succeeding cylinders 2B and 2C are provided in parallel on one side of the combustion chamber. Yes. The first exhaust port 12a and the second exhaust port 12b in the preceding cylinders 2A and 2D and the second intake port 11b and the exhaust port 12 in the subsequent cylinders 2B and 2C are provided in parallel on the other side of the combustion chamber. Yes.

先行気筒２Ａ，２Ｄにおける吸気ポート１１および後続気筒２Ｂ，２Ｃにおける第１吸気ポート１１ａには、吸気通路１５における気筒別の分岐吸気通路１６の下流端が接続されている。各分岐吸気通路１６の下流端近傍には、共通の軸を介して互いに連動する多連スロットル弁１７が設けられており、この多連スロットル弁１７は制御信号に応じてアクチュエータ１８により駆動され、吸入空気量を調節するようになっている。なお、吸気通路１５における集合部より上流の共通吸気通路には吸気流量を検出するエアフローセンサ１９が設けられている。   A downstream end of a branch intake passage 16 for each cylinder in the intake passage 15 is connected to the intake port 11 in the preceding cylinders 2A and 2D and the first intake port 11a in the subsequent cylinders 2B and 2C. In the vicinity of the downstream end of each branch intake passage 16, a multiple throttle valve 17 that is linked to each other via a common shaft is provided. This multiple throttle valve 17 is driven by an actuator 18 in accordance with a control signal, The intake air amount is adjusted. Note that an air flow sensor 19 that detects an intake air flow rate is provided in a common intake passage upstream of the collecting portion in the intake passage 15.

先行気筒２Ａ，２Ｄにおける第１排気ポート１２ａおよび後続気筒２Ｂ，２Ｃにおける排気ポート１２には、排気通路２０における気筒別の分岐排気通路２１の上流端部が接続されている。また、１番気筒２Ａと２番気筒２Ｂとの間および３番気筒２Ｃと４番気筒２Ｄとの間には、それぞれ気筒間ガス通路２２が設けられ、先行気筒である１番，４番気筒２Ａ，２Ｄの第２排気ポート１２ｂに気筒間ガス通路２２の上流端部が接続されるとともに、後続気筒である２番，３番気筒２Ｂ，２Ｃの第２吸気ポート１１ｂに気筒間ガス通路２２の下流端部が接続されている。   An upstream end portion of a branch exhaust passage 21 for each cylinder in the exhaust passage 20 is connected to the first exhaust port 12a in the preceding cylinders 2A and 2D and the exhaust port 12 in the subsequent cylinders 2B and 2C. Further, an inter-cylinder gas passage 22 is provided between the first cylinder 2A and the second cylinder 2B and between the third cylinder 2C and the fourth cylinder 2D, respectively, and the first and fourth cylinders which are the preceding cylinders. The upstream end portion of the inter-cylinder gas passage 22 is connected to the second exhaust ports 12b of 2A and 2D, and the inter-cylinder gas passage 22 is connected to the second intake ports 11b of the second and third cylinders 2B and 2C as the subsequent cylinders. Are connected at the downstream end.

各気筒２Ａ〜２Ｄの排気ポート１２ａ，１２に接続された分岐排気通路２１の合流部よりも下流側部には、排気ガス中の酸素濃度を検出することにより空燃比を検出するＯ2センサ２３が設けられている。このＯ2センサ２３の下流側部、つまり上記分岐排気通路２１が合流した合流部の下流側に位置する排気通路２０には、排気浄化用の三元触媒２４が設けられている。この三元触媒２４は、一般に知られているように、排気ガスの空燃比が理論空燃比（つまり空気過剰率λが１）付近にあるときにＨＣ，ＣＯおよびＮＯｘに対して高い浄化性能を示す触媒である。 An O 2 sensor 23 that detects the air-fuel ratio by detecting the oxygen concentration in the exhaust gas at the downstream side of the junction of the branch exhaust passage 21 connected to the exhaust ports 12a and 12 of the cylinders 2A to 2D. Is provided. A three-way catalyst 24 for purifying exhaust gas is provided in the downstream side of the O 2 sensor 23, that is, in the exhaust passage 20 located on the downstream side of the joining portion where the branched exhaust passage 21 joins. As is generally known, the three-way catalyst 24 has high purification performance for HC, CO, and NOx when the air-fuel ratio of the exhaust gas is near the stoichiometric air-fuel ratio (that is, the excess air ratio λ is 1). It is the catalyst shown.

先行気筒２Ａ，２Ｄにおける吸気ポート１１、第１排気ポート１２ａおよび第２排気ポート１２ｂには、それぞれ吸気弁３１、第１排気弁３２ａおよび第２排気弁３２ｂが設けられ、また、後続気筒２Ｂ，２Ｃにおける第１吸気ポート１１ａ、第２吸気ポート１１ｂおよび排気ポート１２には、それぞれ第１吸気弁３１ａ、第２吸気弁３１ｂおよび排気弁３２が設けられている。そして、各気筒２Ａ〜２Ｄの吸気行程や排気行程が上述のような所定の位相差をもって行われるように、これら吸・排気弁がそれぞれカムシャフト３４等からなる動弁機構により所定のタイミングで開閉するように駆動される。   The intake port 11, the first exhaust port 12a, and the second exhaust port 12b in the preceding cylinders 2A, 2D are provided with an intake valve 31, a first exhaust valve 32a, and a second exhaust valve 32b, respectively, and the subsequent cylinders 2B, The first intake port 11a, the second intake port 11b, and the exhaust port 12 in 2C are provided with a first intake valve 31a, a second intake valve 31b, and an exhaust valve 32, respectively. The intake / exhaust valves are opened and closed at predetermined timings by a valve operating mechanism including the camshaft 34 and the like so that the intake strokes and exhaust strokes of the cylinders 2A to 2D are performed with the predetermined phase difference as described above. To be driven.

上記吸・排気弁のうちで後続気筒２Ｂ，２Ｃに新気を導入させる第１吸気ポート１１ａを開閉する第１吸気弁３１ａの動弁機構には、この第１吸気弁３１ａを作動状態と停止状態に変化させる第１切換機構３５ａが設けられている。また、気筒間ガス通路２２の上流端部および下流端部に設けられた先行気筒２Ａ，２Ｄの第２排気弁３２ｂおよび後続気筒２Ｂ，２Ｃの第２吸気弁３１ｂの動弁機構には、これらの第２排気弁３２ｂおよび第２吸気弁３１ａを停止状態と作動状態とに変化させる第２切換機構３５ｂが設けられている。さらに、先行気筒２Ａ，２Ｄの既燃ガスを排気通路２０に導出する第１排気ポート１２ａ開閉する第１排気弁３２ａの動弁機構には、この第２排気弁３２ｂを作動状態と停止状態とに変化させる第３切換機構３５ｃが設けられている。   Among the intake and exhaust valves, the valve mechanism of the first intake valve 31a that opens and closes the first intake port 11a that introduces fresh air into the succeeding cylinders 2B and 2C is operated and stopped. A first switching mechanism 35a that changes the state is provided. The valve mechanisms of the second exhaust valves 32b of the preceding cylinders 2A and 2D and the second intake valves 31b of the succeeding cylinders 2B and 2C provided at the upstream end and the downstream end of the inter-cylinder gas passage 22 include A second switching mechanism 35b is provided for changing the second exhaust valve 32b and the second intake valve 31a between a stopped state and an activated state. Further, the valve mechanism of the first exhaust valve 32a that opens and closes the first exhaust port 12a that guides the burned gas of the preceding cylinders 2A and 2D to the exhaust passage 20 includes an operation state and a stop state. A third switching mechanism 35c is provided for changing to the above.

上記第１〜第３切換機構３５ａ〜３５ｃは、図４に示すように、上記各弁３１ａ，３１ｂ，３２ａ，３２ｂの上方に配設されたカムシャフト３４と、このカムシャフト３４と上記各弁３１ａ〜３２ｂとの間に配設されたロッカシャフト５５と、このロッカシャフト５５に支持された第１〜第３ロッカアーム５６〜５８とを有している。また、上記カムシャフト３４には、円形の外周面を有する弁停止用の第１カム５２と、弁駆動用の突部（カムノーズ）を有する第２，第３カム５３，５４とが一体に形成されている。この第２，第３カム５３，５４は、同一形状を有し、上記第１カム５２を挟むようにその左右に配設されている。   As shown in FIG. 4, the first to third switching mechanisms 35a to 35c include a camshaft 34 disposed above the valves 31a, 31b, 32a and 32b, and the camshaft 34 and the valves. The rocker shaft 55 is disposed between the rocker shafts 31 a and 32 b and the first to third rocker arms 56 to 58 supported by the rocker shaft 55. The camshaft 34 is integrally formed with a first cam 52 for stopping a valve having a circular outer peripheral surface and second and third cams 53 and 54 having projecting portions (cam noses) for driving the valve. Has been. The second and third cams 53 and 54 have the same shape, and are disposed on the left and right sides of the first cam 52 so as to sandwich the first cam 52.

上記第１ロッカアーム５６は、第１カム５２に対応した位置に配設されるとともに、その先端部には上記各弁３１ａ〜３２ｂの弁軸上端に当接する当接部６０が設けられている。一方、上記第２，第３ロッカアーム５７，５８は、第１ロッカアーム５６を挟むようにその両側方に配設されるとともに、第１ロッカアーム５６とは切り離された状態で、図外の付勢手段により、それぞれ上記第２，第３カム５３，５４に圧接されるように付勢されている。   The first rocker arm 56 is disposed at a position corresponding to the first cam 52, and a contact portion 60 that contacts the upper end of the valve shaft of each of the valves 31a to 32b is provided at the tip thereof. On the other hand, the second and third rocker arms 57 and 58 are disposed on both sides of the first rocker arm 56 so as to sandwich the first rocker arm 56, and are separated from the first rocker arm 56 and are not shown in the drawing. Thus, they are urged to be brought into pressure contact with the second and third cams 53 and 54, respectively.

また、第２，第３ロッカアーム５７，５８は、上記第１ロッカアーム５６と連結可能に構成されている。具体的には、上記第２，第３ロッカアーム５７，５８に設けられたプランジャー（図示せず）が、後述する第１〜第３作動油給排通路３６，３８，４９から供給された作動油により駆動され、その先端部が上記第１ロッカアーム５６に形成された連結孔（図示せず）内に挿入される等により、上記第１ロッカアーム５６と第２，第３ロッカアーム５７，５８とが一体に連結された状態で揺動変位するようになっている。   The second and third rocker arms 57 and 58 are configured to be connectable to the first rocker arm 56. Specifically, the plungers (not shown) provided on the second and third rocker arms 57 and 58 are supplied from first to third hydraulic oil supply / discharge passages 36, 38 and 49, which will be described later. The first rocker arm 56 and the second and third rocker arms 57 and 58 are driven by oil and the tip portion thereof is inserted into a connecting hole (not shown) formed in the first rocker arm 56. It swings and displaces in an integrally connected state.

すなわち、図５に示すように、第１〜第３作動油給排通路３６，３８，４９に設けられた第１〜第３コントロール弁３７，３９，５０からなる制御部材により上記第１〜第３作動油給排通路３６，３８，４９からの作動油の給排を制御して、第１ロッカアーム５６と第２，第３ロッカアーム５７，５８とを一体に連結することにより、上記第２，第３カム５３，５４により駆動される第１，第２ロッカアーム５７，５８の駆動力が第１ロッカアーム５６に伝達されて上記各弁３１ａ〜３２ｂが開閉駆動されることになる。一方、第１ロッカアーム５６と第２，第３ロッカアーム５７，５８との連結状態が解除されると、第２，第３ロッカアーム５７，５８から第１ロッカアーム５６への駆動力の伝達が遮断され、カムシャフト３４が回転しても第１ロッカアーム５６が揺動変位することなく、上記各弁３１ａ〜３２ｂが閉弁状態に維持されるようになっている。   That is, as shown in FIG. 5, the first to third hydraulic oil supply / discharge passages 36, 38, 49 are provided with the first to third control valves 37, 39, 50 by the control member. By controlling the supply and discharge of the hydraulic fluid from the three hydraulic fluid supply / discharge passages 36, 38 and 49, and connecting the first rocker arm 56 and the second and third rocker arms 57 and 58 together, The driving forces of the first and second rocker arms 57 and 58 driven by the third cams 53 and 54 are transmitted to the first rocker arm 56, and the valves 31a to 32b are driven to open and close. On the other hand, when the connection state between the first rocker arm 56 and the second and third rocker arms 57 and 58 is released, transmission of the driving force from the second and third rocker arms 57 and 58 to the first rocker arm 56 is interrupted, Even if the camshaft 34 rotates, the first rocker arm 56 is not oscillated and displaced, so that the valves 31a to 32b are maintained in a closed state.

図５は、駆動、制御系統の構成を示している。この図において、マイクロコンピュータ等からなるエンジン制御用のＥＣＵ（コントロールユニット）４０には、エアフローセンサ１９およびＯ2センサ２３からの信号が入力され、さらに運転状態を判別するためにエンジン回転数を検出する回転数センサ４７およびアクセル開度（アクセルペダル踏込み量）を検出するアクセル開度センサ４８等からの信号も入力されている。また、上記ＥＣＵ４０から、各燃料噴射弁９と、多連スロットル弁１７のアクチュエータ１８と、上記第１，第２のコントロール弁３９とに対して制御信号が出力されるようになっている。 FIG. 5 shows the configuration of the drive and control system. In this figure, signals from the air flow sensor 19 and the O 2 sensor 23 are input to an engine control ECU (control unit) 40 comprising a microcomputer or the like, and the engine speed is detected in order to determine the operating state. Signals from a rotation speed sensor 47 and an accelerator opening sensor 48 for detecting an accelerator opening (accelerator pedal depression amount) are also input. Further, control signals are output from the ECU 40 to the fuel injection valves 9, the actuator 18 of the multiple throttle valve 17, and the first and second control valves 39.

上記ＥＣＵ４０は、後述するようにエンジンの低負荷ないし低回転側の部分負荷領域における特殊運転モードの制御と、高負荷ないし高回転側の運転領域における通常運転モードの制御とを実行する運転モード制御手段を構成するものであり、運転状態判別手段４１と、切換機構制御手段４２と、吸入空気量制御手段４３と、燃焼状態制御手段４４とを備えている。   The ECU 40 performs an operation mode control for executing a special operation mode control in a partial load region on the low load or low rotation side of the engine and a normal operation mode control in an operation region on the high load or high rotation side, as will be described later. The operation state determination means 41, the switching mechanism control means 42, the intake air amount control means 43, and the combustion state control means 44 are provided.

運転状態判別手段４１は、図６に示すように、低負荷低回転側の運転領域Ａ（部分負荷領域）と、高負荷側ないし高回転側の運転領域Ｂとにエンジンの運転領域が分けられた制御用マップを有し、上記回転数センサ４７およびアクセル開度センサ４８等からの信号により調べられるエンジンの運転状態（エンジン回転数およびエンジン負荷）が上記運転領域Ａ，Ｂのいずれの領域にあるかを判別する。そして、この判別結果に基づき、低負荷低回転側の運転領域Ａでは、排気行程にある先行気筒２Ａ，２Ｄから排出される既燃ガスを、そのまま吸気行程にある後続気筒２Ｂ，２Ｃに導入して燃焼させる特殊運転モードが選択され、高負荷側ないし高回転側の運転領域Ｂでは、各気筒２Ａ〜２Ｄをそれぞれ独立させ燃焼させる通常運転モードが選択されるようになっている。   As shown in FIG. 6, the operating state discriminating means 41 divides the engine operating region into an operating region A (partial load region) on the low load and low rotation side and an operating region B on the high load side or high rotation side. The engine operating state (engine speed and engine load) checked by signals from the rotational speed sensor 47 and the accelerator opening sensor 48 and the like is in any of the operating areas A and B. Determine if it exists. Based on the determination result, in the operation region A on the low load and low rotation side, the burned gas discharged from the preceding cylinders 2A and 2D in the exhaust stroke is introduced as it is into the subsequent cylinders 2B and 2C in the intake stroke. The special operation mode for burning is selected, and in the operation region B on the high load side or the high rotation side, the normal operation mode in which the cylinders 2A to 2D are burned independently is selected.

切換機構制御手段４２は、特殊運転モードでは気筒間ガス通路２２を介して先行気筒２Ａ，２Ｄの既燃ガスを後続気筒２Ｂ，２Ｃに導入させる２気筒接続状態とし、通常運転モードでは各気筒２Ａ〜２Ｄにそれぞれ新気を導入させる各気筒独立状態とするようにガス流通経路を変更すべく第１〜第３切換機構３５ａ〜３５ｃを制御するもので、具体的には、運転状態が運転領域Ａ，Ｂのいずれにあるかに応じ、上記第１〜第３コントロール弁３７，３９，５０を介して第１〜第３切換機構３５ａ〜３５ｃに対する作動油の給排を制御することにより、各弁３１ａ〜３２ｂを次の状態とするように構成されている。   The switching mechanism control means 42 is in a two-cylinder connection state in which the burned gas of the preceding cylinders 2A and 2D is introduced into the succeeding cylinders 2B and 2C through the inter-cylinder gas passage 22 in the special operation mode, and each cylinder 2A in the normal operation mode. The first to third switching mechanisms 35a to 35c are controlled so as to change the gas flow path so that each cylinder is brought into an independent state in which fresh air is introduced into 2D. Specifically, the operating state is the operating range. By controlling the supply and discharge of hydraulic fluid to the first to third switching mechanisms 35a to 35c via the first to third control valves 37, 39, and 50 depending on which one is A or B, The valves 31a to 32b are configured to be in the following state.

運転領域Ａ：第１排気弁３２ａおよび第１吸気弁３１ａを停止状態
第２排気弁３２ｂおよび第２吸気弁３１ｂを作動状態
運転領域Ｂ：第１排気弁３２ａおよび第１吸気弁３１ａを作動状態
第２排気弁３２ｂおよび第２吸気弁３１ｂを停止状態 Operating region A: the first exhaust valve 32a and the first intake valve 31a are stopped
Second exhaust valve 32b and second intake valve 31b are in operating state Operating region B: First exhaust valve 32a and first intake valve 31a are in operating state
Stop the second exhaust valve 32b and the second intake valve 31b

上記通常運転モードの各気筒独立状態と特殊運転モードの２気筒接続状態との間でガス流通経路を切り換える際には、下記のように先行気筒２Ａ，２Ｄの空燃比を理論空燃比ないし略理論空燃比として先行気筒２Ａ，２Ｄのみを燃焼させる過渡運転モードを介在させた後に上記ガス流通経路の切換を行うようになっている。   When the gas flow path is switched between the cylinder independent state in the normal operation mode and the two-cylinder connected state in the special operation mode, the air-fuel ratio of the preceding cylinders 2A and 2D is set to the theoretical air-fuel ratio or substantially theoretical as follows. The gas flow path is switched after interposing a transient operation mode in which only the preceding cylinders 2A and 2D are burned as the air-fuel ratio.

すなわち、特殊運転モードの２気筒接続状態から通常運転モードの各気筒独立状態にガス流通経路の切換を行う際には、後続気筒２Ｂ，２Ｃに対する燃料噴射を停止するとともに、先行気筒２Ａ，２Ｄの空燃比を理論空燃比として先行気筒２Ａ，２Ｄのみを燃焼させる過渡運転モードの制御を、例えば１燃焼サイクルまたは２燃焼サイクル程度の間に亘り実行した後、上記第３切換機構３５ｃにより先行気筒２Ａ，２Ｄの第１排気弁３１ｂを作動状態として先行気筒２Ａ，２Ｄから排出された既燃ガスを排気通路２０に導出させるようにする。次いで、この時点から所定の時間差を待って、つまり第３切換機構３５ｃに供給される作動油の圧力が充分に上昇して上記第１排気弁３２ａを作動状態に移行させる移行時間が経過するのを待って、第２切換機構３５ｂにより気筒間ガス通路２２の上流端部および下流端部に設けられた開閉弁（先行気筒２Ａ，２Ｄの第２排気弁３２ｂおよび後続気筒２Ｂ，２Ｃの第２吸気弁３１ｂ）を停止状態とすることにより、ガス流通経路を２気筒接続状態とした後、上記第１切換機構３５ａにより後続気筒２Ｂ，２Ｃの第１吸気弁３１ａを作動状態として各気筒独立状態で連続的に燃焼させる通常運転モードの制御状態に移行する。 That is, when the gas flow path is switched from the two-cylinder connected state in the special operation mode to the cylinder independent state in the normal operation mode, the fuel injection to the subsequent cylinders 2B and 2C is stopped and the preceding cylinders 2A and 2D are stopped. preceding cylinders 2A air-fuel ratio as a physical Ronsora ratio, after the control of the transient operation mode of burning only 2D, it was performed for example over between approximately one combustion cycle or second combustion cycle, preceding cylinders by the third switching mechanism 35c The burned gas discharged from the preceding cylinders 2A and 2D is led out to the exhaust passage 20 by operating the first exhaust valves 31b of 2A and 2D. Next, after waiting for a predetermined time difference from this point, that is, the transition time for causing the pressure of the hydraulic oil supplied to the third switching mechanism 35c to rise sufficiently to shift the first exhaust valve 32a to the operating state elapses. Waiting for the on-off valves (second exhaust valves 32b of the preceding cylinders 2A, 2D and second of the succeeding cylinders 2B, 2C) provided at the upstream end and downstream end of the inter-cylinder gas passage 22 by the second switching mechanism 35b. After the intake valve 31b) is brought into a stopped state, the gas flow path is brought into a two-cylinder connection state, and then the first intake valve 31a of the succeeding cylinders 2B and 2C is activated by the first switching mechanism 35a. Shifts to the control state of the normal operation mode in which combustion is continuously performed.

一方、通常運転モードの各気筒独立状態から特殊運転モードの２気筒接続状態にガス流通経路の切換を行う際には、上記第１切換機構３５ａにより後続気筒２Ｂ，２Ｃの第１吸気弁３１ａを停止状態とするとともに、後続気筒２Ｂ，２Ｃに対する燃料噴射を停止することにより、先行気筒２Ａ，２Ｄの空燃比を略理論空燃比として先行気筒２Ａ，２Ｄのみを燃焼させる過渡運転モードの制御を、例えば１燃焼サイクルまたは２燃焼サイクル程度の間に亘り実行した後、第２切換機構３５ｂにより気筒間ガス通路２２の上流端部および下流端部に設けられた開閉弁（第２排気弁３２ｂおよび第２吸気弁３１ｂ）を作動状態とすることにより、ガス流通経路を２気筒接続状態とする。次いで、この時点から所定の時間差をもって、つまり上記第２切換機構３５ｂに供給される作動油の圧力が充分に上昇して第２排気弁３２ｂおよび第２吸気弁３１ｂを作動状態に移行させる移行時間が経過するのを待って、上記第３切換機構３５ｃにより先行気筒２Ａ，２Ｄの第１排気弁３２ａを停止状態とし、後述するように先行気筒２Ａ，２Ｄの空燃比をリーンに設定し、この先行気筒２Ａ，２Ｄから導出されたリーン空燃比の既燃ガスをそのまま後続気筒２Ｂ，２Ｃに導入させて新たに供給された燃料とともに燃焼させる特殊運転モードの制御状態に移行する。   On the other hand, when the gas flow path is switched from the cylinder independent state in the normal operation mode to the 2-cylinder connected state in the special operation mode, the first intake valves 31a of the succeeding cylinders 2B and 2C are switched by the first switching mechanism 35a. Control of the transient operation mode in which only the preceding cylinders 2A and 2D are burned by setting the air-fuel ratio of the preceding cylinders 2A and 2D to be substantially the stoichiometric air-fuel ratio by stopping the fuel injection to the succeeding cylinders 2B and 2C. For example, after being executed for about one combustion cycle or about two combustion cycles, on-off valves (second exhaust valve 32b and second exhaust valve 32b provided in the upstream end portion and the downstream end portion of the inter-cylinder gas passage 22 by the second switching mechanism 35b. The gas flow path is brought into the two-cylinder connection state by setting the two intake valves 31b) to the operating state. Next, a transition time in which the pressure of the hydraulic oil supplied to the second switching mechanism 35b is sufficiently increased and the second exhaust valve 32b and the second intake valve 31b are shifted to the operating state with a predetermined time difference from this time point. The third switching mechanism 35c causes the first exhaust valves 32a of the preceding cylinders 2A and 2D to stop, and the air-fuel ratios of the preceding cylinders 2A and 2D are set to lean as will be described later. It shifts to a control state of a special operation mode in which burned gas having a lean air-fuel ratio derived from the preceding cylinders 2A and 2D is introduced into the succeeding cylinders 2B and 2C as it is and burned together with newly supplied fuel.

上記吸入空気量制御手段４３は、アクチュエータ１８を制御することによりスロットル弁１７の開度（スロットル開度）を制御するものであり、運転状態に応じてマップ等から目標吸入空気量を求め、その目標吸入空気量に応じてスロットル開度を制御する。この場合、特殊運転モードとされる運転領域Ａでは、後続気筒２Ｂ，２Ｃにおいては分岐吸気通路１６からの吸気導入が遮断された状態で先行気筒２Ａ，２Ｄから導入されるガス中の過剰空気と新たに供給される燃料との比が理論空燃比に対応した値とされつつ燃焼が行われるので、先行、後続の２気筒分の要求トルクに応じた燃料の燃焼に必要な量の空気（２気筒分の燃料の量に対して理論空燃比となる量の空気）が先行気筒２Ａ，２Ｄに供給されるように、スロットル開度が調節される。   The intake air amount control means 43 controls the opening degree of the throttle valve 17 (throttle opening degree) by controlling the actuator 18, and obtains a target intake air amount from a map or the like according to the operating state. The throttle opening is controlled according to the target intake air amount. In this case, in the operation region A in the special operation mode, in the succeeding cylinders 2B and 2C, the excess air in the gas introduced from the preceding cylinders 2A and 2D in a state where the intake air introduction from the branch intake passage 16 is blocked. Combustion is performed while the ratio to the newly supplied fuel is set to a value corresponding to the stoichiometric air-fuel ratio. Therefore, an amount of air (2) required for fuel combustion corresponding to the required torque for the preceding and subsequent two cylinders. The throttle opening is adjusted so that the amount of air corresponding to the stoichiometric air-fuel ratio with respect to the amount of fuel for each cylinder is supplied to the preceding cylinders 2A and 2D.

上記燃焼状態制御手段４４は、燃料噴射制御手段４５と点火制御手段４６とからなっており、燃料噴射制御手段４５により、各気筒２Ａ〜２Ｄに設けられた燃料噴射弁９からの燃料噴射量および噴射タイミングをエンジンの運転状態に応じて制御するとともに、点火制御手段４６により運転状態に応じた点火時期の制御および点火停止等の制御を行う。そして、特に運転状態が図６中の部分負荷領域Ａにある場合と、高負荷ないし高回転の運転領域Ｂにある場合とで燃焼状態の制御（燃料噴射の制御および点火の制御）が変更される。   The combustion state control means 44 is composed of a fuel injection control means 45 and an ignition control means 46. The fuel injection control means 45 causes the fuel injection amount from the fuel injection valves 9 provided in the respective cylinders 2A to 2D and The injection timing is controlled in accordance with the operating state of the engine, and ignition control means 46 controls ignition timing and ignition stop according to the operating state. The control of the combustion state (control of fuel injection and control of ignition) is changed particularly when the operating state is in the partial load region A in FIG. 6 and when it is in the high load or high speed operating region B. The

すなわち、エンジンの運転状態が低負荷ないし低回転側の部分負荷領域Ａにある場合、特殊運転モードでの制御状態として、先行気筒２Ａ，２Ｄに対しては、空燃比を理論空燃比よりも大きいリーン空燃比とするように燃料噴射量を制御するとともに、圧縮行程で燃料を噴射して混合気の成層化を行わせるように噴射タイミングを設定し、かつ、圧縮上死点付近で強制点火を行わせるように点火タイミングを設定する。一方、後続気筒２Ｂ，２Ｃに対しては、先行気筒から導入されたリーン空燃比の既燃ガスに対して燃料を供給し、実質的に理論空燃比となるように燃料噴射量を制御するとともに、吸気行程で燃料を噴射するように噴射タイミングを設定し、かつ、圧縮自己着火を行わせるべく、強制点火を停止させる。   That is, when the engine operating state is in the low load or low rotation side partial load region A, the air-fuel ratio is larger than the stoichiometric air-fuel ratio for the preceding cylinders 2A and 2D as the control state in the special operation mode. The fuel injection amount is controlled so as to obtain a lean air-fuel ratio, the injection timing is set so that fuel is injected during the compression stroke and the mixture is stratified, and forced ignition is performed near the compression top dead center. Ignition timing is set so that it is performed. On the other hand, for the succeeding cylinders 2B and 2C, fuel is supplied to the burned gas having a lean air-fuel ratio introduced from the preceding cylinder, and the fuel injection amount is controlled so as to be substantially the stoichiometric air-fuel ratio. Then, the injection timing is set so as to inject fuel in the intake stroke, and the forced ignition is stopped in order to perform the compression self-ignition.

以上のような当実施形態の装置の作用を、図３、図７および図８を参照しつつ説明する。低負荷低回転側の運転領域Ａでは、上記切換機構制御手段４２および吸入空気量制御手段４３等からなる運転モード制御手段により、特殊運転モードの制御が実行され、原則として前述のように第１排気弁３２ａおよび第１吸気弁３１ａが停止状態、第２排気弁３２ｂおよび第２吸気弁３１ｂが作動状態とされることにより、実質的な新気およびガスの流通経路は図７に示すようになり、先行気筒２Ａ，２Ｄから排出される既燃ガスがそのまま気筒間ガス通路２２を介して後続気筒２Ｂ，２Ｃに導入される（図７中の矢印ｂ）とともに、この後続気筒２Ｂ，２Ｃから排出されるガスのみが排気通路２０に導かれる（図７中の矢印ｃ）ような２気筒接続状態とされる。   The operation of the apparatus of the present embodiment as described above will be described with reference to FIGS. 3, 7 and 8. In the operation region A on the low load and low rotation side, the special operation mode is controlled by the operation mode control means including the switching mechanism control means 42, the intake air amount control means 43 and the like. The exhaust valve 32a and the first intake valve 31a are in a stopped state, and the second exhaust valve 32b and the second intake valve 31b are in an activated state. Thus, the burned gas discharged from the preceding cylinders 2A and 2D is directly introduced into the succeeding cylinders 2B and 2C through the inter-cylinder gas passage 22 (arrow b in FIG. 7), and from the succeeding cylinders 2B and 2C. Only the exhausted gas is led to the exhaust passage 20 (two-cylinder connection state) as indicated by the arrow c in FIG.

この状態において、先行気筒２Ａ，２Ｄにそれぞれ吸気行程で吸気通路１５から新気が導入され（図７中の矢印ａ）、先行気筒２Ａ，２Ｄでは空燃比が理論空燃比よりも大きくて、理論空燃比の略２倍ないしそれより小さい値となるように燃料噴射量が制御されつつ圧縮行程で燃料が噴射され、かつ、所定の点火時期に点火が行われて、リーン空燃比での成層燃焼が行われる（図３参照）。   In this state, fresh air is introduced into the preceding cylinders 2A and 2D from the intake passage 15 in the intake stroke (arrow a in FIG. 7), and the air-fuel ratio in the preceding cylinders 2A and 2D is larger than the stoichiometric air-fuel ratio. The fuel is injected in the compression stroke while the fuel injection amount is controlled to be approximately twice or less than the air-fuel ratio, and ignition is performed at a predetermined ignition timing, so that stratified combustion at a lean air-fuel ratio is achieved. Is performed (see FIG. 3).

また、先行気筒２Ａ，２Ｄの吸気行程と後続気筒２Ｂ，２Ｃの排気行程が重なる期間に、先行気筒２Ａ，２Ｄから導出された既燃ガスがガス通路２２を通って後続気筒２Ｂ，２Ｃに導入される（図３中の白抜き矢印および図７中の矢印ｂ）。そして、後続気筒２Ｂ，２Ｃでは、先行気筒２Ａ，２Ｄから導入されたリーン空燃比の既燃ガスに燃料が供給されて、理論空燃比となるように燃料噴射量が制御されつつ、吸気行程で燃料が噴射された後、圧縮行程の上死点付近で燃焼室内の圧力、温度の上昇により圧縮自己着火が行われる。   Further, burned gas derived from the preceding cylinders 2A and 2D is introduced into the succeeding cylinders 2B and 2C through the gas passage 22 during a period in which the intake strokes of the preceding cylinders 2A and 2D overlap with the exhaust strokes of the succeeding cylinders 2B and 2C. (The white arrow in FIG. 3 and the arrow b in FIG. 7). In the succeeding cylinders 2B and 2C, fuel is supplied to the burned gas having a lean air-fuel ratio introduced from the preceding cylinders 2A and 2D, and the fuel injection amount is controlled so as to become the stoichiometric air-fuel ratio. After the fuel is injected, compression self-ignition is performed near the top dead center of the compression stroke due to an increase in pressure and temperature in the combustion chamber.

この場合、先行気筒２Ａ，２Ｄから排出された高温の既燃ガスが短い気筒間ガス通路２２を通って後続気筒２Ｂ，２Ｃに直ちに導入されるため、後続気筒２Ｂ，２Ｃでは吸気行程で燃焼室内の温度が高くなり、この状態からさらに圧縮行程で圧力、温度が上昇することにより、圧縮行程終期の上死点付近では混合気が自己着火し得る程度まで燃焼室内の温度が上昇する。しかも、上記既燃ガスは先行気筒２Ａ，２Ｄから排出されて後続気筒２Ｂ，２Ｃに導入されるまでの間に充分にミキシングされて均一に分布し、さらに吸気行程で噴射された燃料も圧縮行程終期までの間に燃焼室全体に均一に分散するため、理想的な同時圧縮自己着火の条件を満たすような均一な混合気の分布状態が得られる。そして、同時圧縮自己着火により燃焼が急速に行われ、これにより熱効率が大幅に向上される。   In this case, the high-temperature burned gas discharged from the preceding cylinders 2A and 2D is immediately introduced into the succeeding cylinders 2B and 2C through the short inter-cylinder gas passage 22, so that the succeeding cylinders 2B and 2C have an intake stroke in the combustion chamber. In this state, the pressure and temperature further increase in the compression stroke, and the temperature in the combustion chamber rises to the extent that the air-fuel mixture can self-ignite near the top dead center at the end of the compression stroke. Moreover, the burned gas is sufficiently mixed and evenly distributed from the time when it is discharged from the preceding cylinders 2A and 2D to the time when it is introduced into the succeeding cylinders 2B and 2C, and the fuel injected in the intake stroke is also compressed. Since it is uniformly dispersed throughout the combustion chamber until the end, a uniform air-fuel mixture distribution that satisfies the ideal simultaneous compression self-ignition condition can be obtained. And combustion is rapidly performed by simultaneous compression self-ignition, and, thereby, thermal efficiency is improved significantly.

このように、先行気筒２Ａ，２Ｄでは、リーンでの成層燃焼により熱効率が高められるとともに、成層燃焼を行わない通常のエンジンと比べて吸気負圧が小さくなることでポンピングロスが低減され、一方、後続気筒２Ｂ，２Ｃでは、空燃比が略理論空燃比とされつつ、均一な混合気の分布状態で圧縮自己着火が行われることにより熱効率が高められるとともに、先行気筒２Ａ，２Ｄから押出された既燃ガスが送り込まれるため先行気筒２Ａ，２Ｄよりもさらにポンピングロスが低減される。これらの作用により、燃費が大幅に改善される。   In this way, in the preceding cylinders 2A and 2D, the thermal efficiency is increased by the stratified combustion in lean, and the pumping loss is reduced by reducing the intake negative pressure as compared with a normal engine that does not perform stratified combustion, In the succeeding cylinders 2B and 2C, while the air-fuel ratio is substantially the stoichiometric air-fuel ratio, the compression self-ignition is performed in a uniform air-fuel mixture distribution state, and the thermal efficiency is increased, and the existing cylinders 2A and 2D that have been extruded from the preceding cylinders 2A and 2D Since the fuel gas is sent, the pumping loss is further reduced as compared with the preceding cylinders 2A and 2D. These effects greatly improve fuel efficiency.

また、先行気筒２Ａ，２Ｄでは理論空燃比の略２倍もしくはそれに近いリーン空燃比とされることでＮＯｘ発生量が比較的少なく抑えられる。一方、後続気筒２Ｂ，２Ｃでは、先行気筒２Ａ，２Ｄから既燃ガスが導入されることで多量のＥＧＲが行われているのと同等の状態となるとともに、同時圧縮自己着火による急速燃焼が行われて可及的に酸素と窒素との反応が避けられることから、ＮＯｘの発生が充分に抑制される。このような点からもエミッション性能の向上に有利となる。しかも、後続気筒２Ｂ，２Ｃでの圧縮自己着火が先行気筒２Ａ，２Ｄから排出される既燃ガスの熱を利用して達成されるため、気筒内の温度を上昇させる加熱手段を用いたりエンジンの圧縮比を極端に高くしたりする等の格別の工夫を講じることなく、容易に圧縮自己着火を行わせることができる。   In addition, in the preceding cylinders 2A and 2D, the lean air-fuel ratio is set to approximately twice or close to the theoretical air-fuel ratio, so that the NOx generation amount can be suppressed to be relatively small. On the other hand, in the succeeding cylinders 2B and 2C, the burned gas is introduced from the preceding cylinders 2A and 2D so that a large amount of EGR is performed, and rapid combustion by simultaneous compression self-ignition is performed. As a result, the reaction between oxygen and nitrogen is avoided as much as possible, so that the generation of NOx is sufficiently suppressed. From this point, it is advantageous for improving the emission performance. Moreover, since the compression self-ignition in the succeeding cylinders 2B and 2C is achieved by using the heat of the burned gas discharged from the preceding cylinders 2A and 2D, a heating means for increasing the temperature in the cylinder is used. Compression self-ignition can be easily performed without taking special measures such as extremely increasing the compression ratio.

また、少なくとも後続気筒２Ｂ，２Ｃの圧縮自己着火行われる部分負荷領域Ａで、後続気筒２Ｂ，２Ｃから排出される排気ガス中の酸素濃度を、理論空燃比の燃焼状態に対応した値となるように後続気筒２Ｂ，２Ｃの空燃比を制御するように構成したため、先行気筒２Ａ，２Ｄでリーンな空燃比で燃焼を行わせつつ、理論空燃比で燃焼した後続気筒２Ｂ，２Ｃの既燃ガスのみを排気通路２０に導出させることができる。したがって、従来のリーンバーンエンジンのようにリーンＮＯｘ触媒を設けることなく、三元触媒２４だけで充分に排気浄化性能を確保することができる。そして、上記リーンＮＯｘ触媒を設ける必要がないことから、リーンＮＯｘ触媒のＮＯｘ吸蔵量増大時におけるＮＯｘの放出、還元のための一時的な空燃比のリッチ化を行う必要がなく、燃費改善の目減りを避けることができるとともに、リーンＮＯｘ触媒が硫黄被毒するという問題を生じることもない。   Further, at least in the partial load region A where the subsequent self-ignition of the subsequent cylinders 2B and 2C is performed, the oxygen concentration in the exhaust gas discharged from the subsequent cylinders 2B and 2C becomes a value corresponding to the combustion state of the stoichiometric air-fuel ratio. Since the air-fuel ratio of the succeeding cylinders 2B and 2C is controlled at the same time, only the burned gas of the succeeding cylinders 2B and 2C burned at the stoichiometric air-fuel ratio while burning at the lean air-fuel ratio in the preceding cylinders 2A and 2D. Can be led to the exhaust passage 20. Therefore, exhaust purification performance can be sufficiently ensured with only the three-way catalyst 24 without providing a lean NOx catalyst as in a conventional lean burn engine. Further, since it is not necessary to provide the lean NOx catalyst, it is not necessary to temporarily enrich the air-fuel ratio for releasing and reducing NOx when the NOx occlusion amount of the lean NOx catalyst is increased. And the problem that the lean NOx catalyst is sulfur poisoned does not occur.

一方、高負荷側ないし高回転側の運転領域Ｂでは通常運転モードとされ、前述のように第１排気弁３２ａおよび第１吸気弁３１ａが作動状態、第２排気弁３２ｂおよび第２吸気弁３１ｂが停止状態とされることにより、実質的な新気およびガスの流通経路は図８に示すようになり、各気筒２Ａ〜２Ｄの吸気ポート１１，１１ａおよび排気ポート１２ａ，１２が独立した状態で、吸気通路１５から各気筒２Ａ〜２Ｄの吸気ポート１１，１１ａに新気が導入されるとともに、各気筒２Ａ〜２Ｄの排気ポート１２，１２ａから排気通路２０に既燃ガスが排出される。この場合には、各気筒２Ａ〜２Ｄの空燃比が理論空燃比もしくはそれよりリッチとなるように吸入空気量および燃料噴射量が制御されることにより、出力性能が確保されることになる。   On the other hand, in the operation region B on the high load side or the high rotation side, the normal operation mode is set. As described above, the first exhaust valve 32a and the first intake valve 31a are in the operating state, and the second exhaust valve 32b and the second intake valve 31b. When the engine is stopped, the actual fresh air and gas flow paths are as shown in FIG. 8, and the intake ports 11 and 11a and the exhaust ports 12a and 12 of the cylinders 2A to 2D are independent. Then, fresh air is introduced from the intake passage 15 to the intake ports 11 and 11a of the cylinders 2A to 2D, and burned gas is discharged from the exhaust ports 12 and 12a of the cylinders 2A to 2D to the exhaust passage 20. In this case, the output performance is ensured by controlling the intake air amount and the fuel injection amount so that the air-fuel ratios of the respective cylinders 2A to 2D become the stoichiometric air-fuel ratio or richer.

そして、上記のようにエンジンの運転状態の変化に応じて通常運転モードの各気筒独立状態と特殊運転モードの２気筒接続状態との間でガス流通経路を切り換える際に、先行気筒２Ａ，２Ｄの空燃比を理論空燃比ないし略理論空燃比として先行気筒２Ａ，２Ｄのみを燃焼させる過渡運転モードを介在させて上記ガス流通経路の切換を行うように構成したため、ガス流通経路の切換過渡期にエミッション性能が低下したり、トルクショックが発生したりする等の問題を生じることなく、上記ガス流通経路の切換を適正に実行できるという利点がある。   As described above, when the gas flow path is switched between each cylinder independent state in the normal operation mode and the two-cylinder connection state in the special operation mode in accordance with a change in the operation state of the engine, the preceding cylinders 2A and 2D Since the gas flow path is switched by interposing a transient operation mode in which only the preceding cylinders 2A and 2D are burned with the air-fuel ratio being the stoichiometric or substantially stoichiometric air-fuel ratio, the emission is performed in the transition period of the gas flow path. There is an advantage that the switching of the gas flow path can be performed properly without causing problems such as a decrease in performance and occurrence of torque shock.

例えば、特殊運転モードの２気筒接続状態から通常運転モードの各気筒独立状態にガス流通経路を切り換える際に、上記過渡運転モードを介在させることなく、部分負荷領域Ａから高負荷ないし高回転側の運転領域Ｂに移行した時点で、各気筒独立状態に直接移行させた場合には、先行気筒２Ａ，２Ｄに２気筒分の新気を導入させた状態から、先行気筒２Ａ，２Ｄおよび後続気筒２Ｂ，２Ｃに必要とされる新気をそれぞれ個別に導入させる状態に直ちに移行させるために、各気筒２Ａ〜２Ｄに導入される新気量を適正値に急減させる必要がある。しかし、上記運転領域の移行時点でスロットル開度を減少させたとしても吸気量制御の応答遅れが生じることにより、各気筒２Ａ〜２Ｄに導入される新気量が目標空気量よりも多くなる傾向があり、この状態で各気筒２Ａ〜２Ｄを理論空燃比で燃焼させるために、燃料噴射量を目標空気量に対応した値よりも増大させると、エンジン出力が急増してトルクショックが生じることが避けられない。   For example, when the gas flow path is switched from the two-cylinder connected state in the special operation mode to the individual cylinder independent state in the normal operation mode, the partial load region A can be switched from the high load to the high rotation side without interposing the transient operation mode. At the time of transition to the operation region B, when the transition is made directly to the cylinder independent state, the preceding cylinders 2A, 2D and the succeeding cylinders 2B are started from the state where fresh air for two cylinders is introduced into the preceding cylinders 2A, 2D. , 2C, the amount of fresh air introduced into each of the cylinders 2A to 2D needs to be rapidly reduced to an appropriate value in order to immediately shift to a state where the fresh air required for 2C is individually introduced. However, even if the throttle opening is decreased at the time of transition to the operation region, a response delay of the intake air amount control occurs, so that the fresh air amount introduced into each cylinder 2A to 2D tends to be larger than the target air amount. In this state, in order to burn the cylinders 2A to 2D at the stoichiometric air-fuel ratio, if the fuel injection amount is increased from a value corresponding to the target air amount, the engine output may rapidly increase and torque shock may occur. Inevitable.

なお、トルクショックの発生を防止するために、各気筒２Ａ〜２Ｄに導入される新気量が目標空気量よりも多い状態で、各気筒２Ａ〜２Ｄに対する燃料噴射量を目標空気量に対応した値に設定することも考えられるが、この場合には、各気筒２Ａ〜２Ｄの空燃比が理論空燃比よりもリーンとなって酸素過剰状態の既燃ガスが排気通路２０に導出されることになる。このため、三元触媒２４によるＨＣ、ＣＯおよびＮＯｘの排気ガスの浄化性能が充分に発揮されず、エミッション性能が低下することが避けられない。   In order to prevent the occurrence of torque shock, the fuel injection amount for each cylinder 2A to 2D is made to correspond to the target air amount in a state where the fresh air amount introduced into each cylinder 2A to 2D is larger than the target air amount. However, in this case, the air-fuel ratio of each of the cylinders 2A to 2D is leaner than the stoichiometric air-fuel ratio, and the burned gas in the oxygen excess state is led to the exhaust passage 20. Become. For this reason, the purification performance of the exhaust gas of HC, CO and NOx by the three-way catalyst 24 is not sufficiently exhibited, and it is inevitable that the emission performance is lowered.

これに対して特殊運転モードの２気筒接続状態から通常運転モードの各気筒独立状態にガス流通経路を切り換える際に、先行気筒２Ａ，２Ｄに導入される新気量が目標空気量よりも多くなるのに対応させて先行気筒２Ａ，２Ｄに対する燃料噴射量を増大させることにより、その空燃比を理論空燃比ないし略理論空燃比とするとともに、後続気筒２Ｂ，２Ｃに対する燃料噴射を停止することにより、先行気筒２Ａ，２Ｄのみを燃焼させる過渡運転モードを介在させた後に、上記ガス流通経路の切換を行うように構成した場合には、吸気量制御の応答遅れが生じることに起因してエンジン出力が急増するトルクショックが発生したり、各気筒２Ａ〜２Ｄの空燃比が理論空燃比よりもリーンとなることに起因してエミッション性能が低下したりする等の弊害を防止しつつ、上記特殊運転モードの２気筒接続状態から通常運転モードの各気筒独立状態にスムーズに移行させることができる。   In contrast, when the gas flow path is switched from the two-cylinder connected state in the special operation mode to the individual cylinder independent state in the normal operation mode, the amount of fresh air introduced into the preceding cylinders 2A and 2D becomes larger than the target air amount. By increasing the fuel injection amount for the preceding cylinders 2A and 2D correspondingly, the air-fuel ratio is made the stoichiometric or substantially stoichiometric air-fuel ratio, and the fuel injection for the succeeding cylinders 2B and 2C is stopped. If the gas flow path is switched after the transient operation mode in which only the preceding cylinders 2A and 2D are burned, the engine output is reduced due to the response delay of the intake air amount control. A sudden increase in torque shock occurs, or the emission performance deteriorates due to the air-fuel ratio of the cylinders 2A to 2D being leaner than the stoichiometric air-fuel ratio. While preventing harmful effects, it is possible to shift smoothly to each cylinder independently state of the normal operation mode from the two-cylinder connection state of the special operation mode.

一方、上記通常運転モードの各気筒独立状態から特殊運転モードの２気筒接続状態にガス流通経路を切り換える際に、上記過渡運転モードを介在させることなく、高負荷ないし高回転側の運転領域Ｂから部分負荷領域Ａに移行した時点で、２気筒接続状態に直接移行させた場合には、先行気筒２Ａ，２Ｄおよび後続気筒２Ｂ，２Ｃに必要とされる新気をそれぞれ個別に導入させる状態から先行気筒２Ａ，２Ｄに対して２気筒分の新気を導入させる状態に直ちに移行させるためには、先行気筒２Ａ，２Ｄに導入される新気量を適正値に急増させる必要がある。しかし、上記運転領域の移行時点でスロットル開度を増大させたとしても吸気量制御の応答遅れが生じることにより、先行気筒２Ａ，２Ｄに導入される新気量が目標吸気量に対応した値よりも少なくなる傾向があり、この状態で先行気筒２Ａ，２Ｄの空燃比を理論空燃比に２倍以上に設定すると、各気筒２Ａ〜２Ｄに対する燃料噴射量が過度に少なくなって失火が生じる可能性がある。   On the other hand, when the gas flow path is switched from the cylinder independent state in the normal operation mode to the two-cylinder connection state in the special operation mode, the operation region B on the high load or high rotation side is not involved without interposing the transient operation mode. When the transition is made to the partial load region A, when the transition is made directly to the two-cylinder connection state, the fresh air required for the preceding cylinders 2A and 2D and the succeeding cylinders 2B and 2C is introduced separately from the preceding state. In order to immediately shift to the state in which the fresh air for two cylinders is introduced into the cylinders 2A and 2D, it is necessary to rapidly increase the fresh air amount introduced into the preceding cylinders 2A and 2D to an appropriate value. However, even if the throttle opening is increased at the time of transition to the operation region, a response delay of the intake air amount control occurs, so that the fresh air amount introduced into the preceding cylinders 2A and 2D is larger than the value corresponding to the target intake air amount. In this state, if the air-fuel ratio of the preceding cylinders 2A, 2D is set more than twice the stoichiometric air-fuel ratio, the fuel injection amount for each of the cylinders 2A-2D may become excessively small and misfire may occur. There is.

これに対して通常運転モードの各気筒独立状態から特殊運転モードの２気筒接続状態にガス流通経路を切り換える際に、上記のように先行気筒２Ａ，２Ｄの空燃比を理論空燃比ないし略理論空燃比として先行気筒２Ａ，２Ｄのみを燃焼させる過渡運転モードを介在させた後に上記ガス流通経路の切換を行うように構成した場合には、吸気量制御の応答遅れが生じることに起因した失火の発生を防止しつつ、上記通常運転モードの各気筒独立状態から特殊運転モードの２気筒接続状態にスムーズに移行させることができる。   On the other hand, when the gas flow path is switched from the individual cylinder independent state in the normal operation mode to the two-cylinder connection state in the special operation mode, the air-fuel ratio of the preceding cylinders 2A and 2D is set to the stoichiometric air-fuel ratio or substantially stoichiometric air as described above. If the gas flow path is switched after a transient operation mode in which only the preceding cylinders 2A and 2D are burned as the fuel ratio is generated, misfiring occurs due to a response delay in intake air amount control. Thus, it is possible to smoothly shift from the cylinder independent state in the normal operation mode to the two-cylinder connected state in the special operation mode.

なお、通常運転モードの各気筒独立状態と特殊運転モードの２気筒接続状態との間でガス流通経路を切り換える際に、後続気筒２Ｂ，２Ｃの空燃比を理論空燃比ないし略理論空燃比として後続気筒２Ｂ，２Ｃのみを燃焼させる過渡運転モードを介在させることも可能である。しかし、上記の構成とした場合には、先行気筒２Ａ，２Ｄの吸気弁３１が常時作動状態にあるため、各気筒独立状態で先行気筒２Ａ，２Ｄに対する燃料噴射を停止しても、上記過渡運転モードの実行時に、先行気筒２Ａ，２Ｄ内を通過した新気が直接、排気通路２０に導出されるのを避けられない。このため、先行気筒２Ａ，２Ｄ内を通過した新気と、後続気筒２Ｂ，２Ｃから導出された既燃ガスとが混ざり合った状態で三元触媒２４に供給され、排気通路２０内が酸素過剰状態となることに起因して三元触媒２４によるＨＣ、ＣＯおよびＮＯｘの浄化性能が低下することになる。   When the gas flow path is switched between the independent state of each cylinder in the normal operation mode and the two-cylinder connection state in the special operation mode, the succeeding cylinders 2B and 2C have the air-fuel ratio as the theoretical air-fuel ratio or the substantially stoichiometric air-fuel ratio. It is also possible to interpose a transient operation mode in which only the cylinders 2B and 2C are burned. However, in the case of the above configuration, since the intake valves 31 of the preceding cylinders 2A and 2D are always in an operating state, the transient operation is performed even if the fuel injection to the preceding cylinders 2A and 2D is stopped in each cylinder independent state. When the mode is executed, it is inevitable that fresh air that has passed through the preceding cylinders 2A and 2D is led directly to the exhaust passage 20. Therefore, fresh air that has passed through the preceding cylinders 2A and 2D and burned gas derived from the succeeding cylinders 2B and 2C are mixed and supplied to the three-way catalyst 24, and the exhaust passage 20 is excessively oxygenated. Due to the state, the purification performance of HC, CO, and NOx by the three-way catalyst 24 is lowered.

これに対して通常運転モードの各気筒独立状態と特殊運転モードの２気筒接続状態との間でガス流通経路を切り換える際に、上記のように先行気筒２Ａ，２Ｄの空燃比を理論空燃比ないし略理論空燃比として先行気筒２Ａ，２Ｄのみを燃焼させる過渡運転モードを介在させるように構成した場合には、この過渡運転モードの実行時に、後続気筒２Ｂ，２Ｃの新気導入弁（第１吸気弁３１ａ）を閉止状態とすることにより、後続気筒２Ｂ，２Ｃ内に新気が導入されるのを防止することができるため、この後続気筒２Ｂ，２Ｃ内を通過した新気と、先行気筒２Ａ，２Ｄから導出された既燃ガスとが混ざり合った状態で三元触媒２４に導入されるという事態を生じることがなく、排気通路２０に設けられた単一の三元触媒２４により、先行気筒２Ａ，２Ｄから導出された既燃ガスを効果的に浄化してエミッション性能を確保できるという利点がある。   On the other hand, when the gas flow path is switched between the cylinder independent state in the normal operation mode and the two-cylinder connected state in the special operation mode, the air-fuel ratio of the preceding cylinders 2A and 2D is set to the stoichiometric air-fuel ratio or the air-fuel ratio as described above. When the transient operation mode in which only the preceding cylinders 2A and 2D are burned is interposed as the substantially stoichiometric air-fuel ratio, the fresh air introduction valves (first intake valves) of the subsequent cylinders 2B and 2C are executed during the execution of the transient operation mode. By closing the valve 31a), it is possible to prevent fresh air from being introduced into the succeeding cylinders 2B, 2C. Therefore, fresh air that has passed through the succeeding cylinders 2B, 2C and the preceding cylinder 2A , 2D is not introduced into the three-way catalyst 24 in a state of being mixed with the burned gas derived from the 2D, and a single three-way catalyst 24 provided in the exhaust passage 20 allows the preceding cylinder to be introduced. 2A It can be advantageously ensured emission performance by purifying combustion gases derived from the 2D effectively.

さらに、上記実施形態では、特殊運転モードの２気筒接続状態から通常運転モードの各気筒独立状態にガス流通経路を切り換える際に、気筒間ガス通路２２の開閉弁（第２排気弁３２ｂおよび第２吸気弁３１ｂ）を停止状態とする前に先行気筒２Ａ，２Ｄの第１排気弁３２ａを作動状態とするようにしたため、先行気筒２Ａ，２Ｄに設けられた第１排気弁３２ａおよび第２排気弁３２ｂの両方が一時的に閉止状態となるという事態の発生を確実に防止し、先行気筒２Ａ，２Ｄの排気性を確保してその燃焼を確実に行わせることができる。また、上記通常運転モードの各気筒独立状態から特殊運転モードの２気筒接続状態にガス流通経路を切り換える際には、先行気筒２Ａ，２Ｄの第１排気弁３２ａを停止状態とする前に、気筒間ガス通路２２の開閉弁（第２排気弁３２ｂおよび第２吸気弁３１ｂ）を作動状態とするようにしたため、先行気筒２Ａ，２Ｄに設けられた両排気弁３２ａ，３２ｂが同時に閉止状態となるのを防止して先行気筒２Ａ，２Ｄを確実に燃焼させることができる。   Furthermore, in the above embodiment, when switching the gas flow path from the two-cylinder connected state in the special operation mode to the cylinder independent state in the normal operation mode, the on-off valve (the second exhaust valve 32b and the second exhaust valve 32b) Since the first exhaust valves 32a of the preceding cylinders 2A and 2D are activated before the intake valve 31b) is stopped, the first and second exhaust valves 32a and 2D provided in the preceding cylinders 2A and 2D are operated. It is possible to reliably prevent the occurrence of a situation in which both of the cylinders 32b are temporarily closed, and to ensure the exhaust performance of the preceding cylinders 2A and 2D and to reliably perform the combustion. Further, when the gas flow path is switched from the cylinder independent state in the normal operation mode to the two-cylinder connection state in the special operation mode, before the first exhaust valves 32a of the preceding cylinders 2A and 2D are stopped, the cylinders are stopped. Since the on-off valves (second exhaust valve 32b and second intake valve 31b) of the inter-gas passage 22 are activated, both the exhaust valves 32a and 32b provided in the preceding cylinders 2A and 2D are simultaneously closed. The preceding cylinders 2A and 2D can be reliably burned.

また、上記実施形態に示すように、各気筒２Ａ〜２Ｄに設けられた吸・排気弁の動弁機構に、各弁を作動状態と停止状態とに変化させてガス流通経路を切り換える第１〜第３切換機構３５ａ〜３５ｃを設けるとともに、この第１〜第３切換機構３５ａ〜３５ｃに対する油圧の給排を制御することにより上記各弁を作動状態と停止状態とに変化させる第１〜第３コントロール弁３７，３９，５０からなる複数の制御部材を設け、これらの制御部材による上記第１〜第３切換機構３５ａ〜３５ｃの動作開始時期に時間差をもたせるように構成した場合には、上記第１〜第３切換機構３５ａ〜３５ｃに供給される作動油圧の上昇遅れが生じるのを効果的に防止して上記各弁を作動状態と停止状態とに迅速に変化させることができる。したがって、例えば特殊運転モードの２気筒接続状態から通常運転モードの各気筒独立状態にガス流通経路を切り換える際に、気筒間ガス通路２２の開閉弁（第２排気弁３２ｂおよび第２吸気弁３１ｂ）を停止状態とする前に先行気筒２Ａ，２Ｄの第１排気弁３２ａを作動状態とする制御を迅速かつ適正に実行し、これにより先行気筒２Ａ，２Ｄの排気性が損なわれるようなガス流通経路が形成されるという事態の発生を効果的に防止して先行気筒２Ａ，２Ｄを確実に燃焼させることができる。   In addition, as shown in the above-described embodiment, first to first gas switching paths are switched to the valve operating mechanisms of the intake and exhaust valves provided in the respective cylinders 2 </ b> A to 2 </ b> D by changing each valve between an operating state and a stopped state. While providing the 3rd switching mechanism 35a-35c, the said 1st-3rd which changes each said valve to an operation state and a stop state by controlling supply and discharge of the hydraulic pressure with respect to this 1st-3rd switching mechanism 35a-35c. In the case where a plurality of control members including the control valves 37, 39, and 50 are provided and the operation start timings of the first to third switching mechanisms 35a to 35c by these control members are set to have a time difference, It is possible to effectively prevent the hydraulic oil pressure supplied to the first to third switching mechanisms 35a to 35c from being delayed, and to quickly change the valves to the operating state and the stopped state. Therefore, for example, when the gas flow path is switched from the two-cylinder connection state in the special operation mode to the cylinder independent state in the normal operation mode, the on-off valve (the second exhaust valve 32b and the second intake valve 31b) of the inter-cylinder gas passage 22 Gas flow path that quickly and properly executes control to activate the first exhaust valves 32a of the preceding cylinders 2A and 2D before the engine is stopped, thereby impairing the exhaust performance of the preceding cylinders 2A and 2D Can be effectively prevented, and the preceding cylinders 2A and 2D can be reliably burned.

なお、本発明の装置の具体的構成は上記実施形態に限定されず、種々変更可能であり、例えば特殊運転モードとされる運転領域Ａの全域で、後続気筒２Ｂ，２Ｃを圧縮自己着火により燃焼させるようにした上記各実施形態に代え、特殊運転モードとされる運転領域Ａのうちの一部、例えば燃焼室内の温度、圧力が圧縮自己着火可能な状態に達しにくい極低速低負荷の領域では、後続気筒２Ｂ，２Ｃに対して所定の点火時期に点火プラグ７による点火を行わせ、強制点火により燃焼させるようにしてもよく、あるいはエンジン温度が低いときに、後続気筒２Ｂ，２Ｃを強制点火により燃焼させるようにしてもよい。   The specific configuration of the device of the present invention is not limited to the above embodiment, and can be variously changed. For example, the subsequent cylinders 2B and 2C are burned by compression self-ignition over the entire operation region A in the special operation mode. In place of the above-described embodiments, in a part of the operation area A that is set to the special operation mode, for example, in the extremely low speed and low load area in which the temperature and pressure in the combustion chamber are difficult to reach a state capable of compression self-ignition. The subsequent cylinders 2B and 2C may be ignited by the spark plug 7 at a predetermined ignition timing and burned by forced ignition, or the subsequent cylinders 2B and 2C are forcibly ignited when the engine temperature is low. You may make it burn by.

また、上記基本実施形態では各弁の動弁機構に設けられた第１〜第３切換機構３５ａ〜３５ｃを用いて２気筒接続状態と各気筒独立状態とにガス流通経路を切換可能としているが、吸・排気通路および気筒間ガス通路に開閉弁を設けてこれらの通路の開閉により２気筒接続状態と各気筒独立状態とに切換え得るようにしてもよい。   In the basic embodiment, the gas flow path can be switched between the two-cylinder connected state and the cylinder-independent state using the first to third switching mechanisms 35a to 35c provided in the valve operating mechanism of each valve. In addition, an open / close valve may be provided in the intake / exhaust passage and the inter-cylinder gas passage so that the two-cylinder connected state and the individual cylinder independent state can be switched by opening and closing these passages.

本発明の一実施形態による制御装置を備えたエンジン全体の概略平面図である。It is a schematic plan view of the whole engine provided with the control apparatus by one Embodiment of this invention. エンジン本体等の概略断面図である。It is a schematic sectional drawing, such as an engine main body. 各気筒の排気行程、吸気行程、燃料噴射時期および点火時期等を示す図である。It is a figure which shows the exhaust stroke of each cylinder, an intake stroke, fuel injection timing, ignition timing, etc. FIG. 切換機構の具体的構成を示す斜視図である。It is a perspective view which shows the specific structure of a switching mechanism. 制御系統のブロック図である。It is a block diagram of a control system. 運転状態に応じた制御を行うための運転領域のマップを示す説明図である。It is explanatory drawing which shows the map of the driving | operation area | region for performing control according to a driving | running state. 低負荷低回転時の実質的な新気およびガスの流通経路を示す説明図である。It is explanatory drawing which shows the distribution path | route of substantial fresh air and gas at the time of low load low rotation. 高負荷高回転時の実質的な新気およびガスの流通経路を示す説明図である。It is explanatory drawing which shows the distribution path | route of substantial fresh air and gas at the time of high load high rotation.

符号の説明Explanation of symbols

１ エンジン本体
２Ａ，２Ｄ 先行気筒
２Ｂ，２Ｃ 後続気筒
９ 燃料噴射弁
１５ 吸気通路
２０ 排気通路
２２ 気筒間ガス通路
２４ 三元触媒
３１ａ 第１吸気弁（後続気筒の吸気弁）
３１ｂ 第２吸気弁（後続気筒の吸気弁）
３２ａ 第１排気弁（先行気筒の排気弁）
３２ｂ 第２排気弁（先行気筒の排気弁）
３５ａ〜３５ｃ 切換機構
４０ ＥＣＵ（運転モード制御手段） DESCRIPTION OF SYMBOLS 1 Engine main body 2A, 2D Predecessor cylinder 2B, 2C Subsequent cylinder 9 Fuel injection valve 15 Intake passage 20 Exhaust passage 22 Inter-cylinder gas passage 24 Three-way catalyst 31a First intake valve (intake valve of succeeding cylinder)
31b Second intake valve (subsequent cylinder intake valve)
32a First exhaust valve (exhaust valve of the preceding cylinder)
32b Second exhaust valve (exhaust valve of the preceding cylinder)
35a-35c switching mechanism 40 ECU (operation mode control means)

Claims (3)

各気筒の燃焼サイクルが所定の位相差をもつように設定され、各気筒にそれぞれ新気を導入させて各気筒を独立状態で燃焼させる通常運転モードの制御と、エンジンの低回転低負荷領域で、排気行程と吸気行程が重なる一対の気筒間において排気行程にある先行気筒から排出される既燃ガスがそのまま吸気行程にある後続気筒に気筒間ガス通路を介して導入され、この後続気筒から排出されるガスが三元触媒を備えた排気通路に導かれるような２気筒接続状態としつつ、先行気筒の空燃比を理論空燃比よりも大きいリーン空燃比として燃焼を行わせ、この先行気筒から後続気筒にリーン空燃比の既燃ガスを導入させて後続気筒の空燃比を理論空燃比とするように新たに供給された燃料とともに燃焼させる特殊運転モードの制御とを実行する運転モード制御手段を備えた多気筒の火花式点火エンジンにおいて、
上記通常運転モードの各気筒独立状態と特殊運転モードの２気筒接続状態との間でガス流通経路を切り換える際に、後続気筒に対する燃料供給を停止するとともに、先行気筒の空燃比が理論空燃比となるように先行気筒に対してのみ燃料供給を行って先行気筒のみを燃焼させる過渡運転モードを介在させて上記ガス流通経路の切換を行うことを特徴とする火花点火式エンジンの制御装置。 Combustion cycle of each cylinder are set to have a predetermined phase difference, the control of the normal operation mode in which combustion in the cylinders independently of each cylinder by introducing fresh air conditions, at a low speed and low load region of the engine The burned gas discharged from the preceding cylinder in the exhaust stroke between a pair of cylinders in which the exhaust stroke and the intake stroke overlap is directly introduced into the subsequent cylinder in the intake stroke via the inter-cylinder gas passage and discharged from this subsequent cylinder. Combustion is performed with the air-fuel ratio of the preceding cylinder set to a lean air-fuel ratio larger than the stoichiometric air-fuel ratio while the two-cylinder connection state is such that the gas to be discharged is led to the exhaust passage provided with the three-way catalyst. luck to perform the control of the special operation mode to burn together with newly supplied fuel to the cylinders by introducing burned gas of a lean air-fuel ratio and physical Ronsora-fuel ratio of the following cylinders by The spark-ignition engine of a multi-cylinder having a mode control means,
When switching the gas flow path between the two-cylinder connection state of each cylinder independently state and the special operation mode of the normal operation mode, stops the fuel supply to the following cylinders, the air-fuel ratio of the preceding cylinders and the stoichiometric air-fuel ratio A control device for a spark ignition engine, wherein the gas flow path is switched by interposing a transient operation mode in which fuel is supplied only to the preceding cylinder and only the preceding cylinder is burned. 気筒間ガス通路に設けられた開閉弁を作動状態と停止状態に切り換えるように制御する制御部材と、先行気筒に設けられた排気弁の作動状態と停止状態とに切り換えるように制御する制御部材とを別々に設け、特殊運転モードの２気筒接続状態から通常運転モードの各気筒独立状態にガス流通経路の切換を行う際には、気筒間ガス通路の開閉弁を停止状態とする前に先行気筒の排気弁を作動状態とし、通常運転モードの各気筒独立状態から特殊運転モードの２気筒接続状態にガス流通経路の切換を行う際には、先行気筒の排気弁を停止状態とする前に気筒間ガス通路の開閉弁を作動状態とすることを特徴とする請求項１に記載の火花点火式エンジンの制御装置。 A control member for controlling the on-off valve provided in the inter-cylinder gas passage to be switched between an operating state and a stopped state; and a control member for controlling the switching between an operating state and a stopped state of an exhaust valve provided in the preceding cylinder; When the gas flow path is switched from the two-cylinder connected state in the special operation mode to the individual cylinder independent state in the normal operation mode, the preceding cylinder is set before the on-off valve of the inter-cylinder gas passage is stopped. When the gas flow path is switched from the cylinder independent state in the normal operation mode to the two-cylinder connection state in the special operation mode, the cylinder before the exhaust valve of the preceding cylinder is stopped. The control device for a spark ignition engine according to claim 1, wherein an on-off valve of the inter-gas passage is put into an operating state . 各気筒に設けられた吸気弁および排気弁の動弁機構に、各弁を作動状態と停止状態とに変化させてガス流通経路を切り換える切換機構を設けるとともに、この切換機構に対する油圧の給排を制御することにより上記各弁を作動状態と停止状態とに変化させる複数の制御部材を設け、この制御部材による上記切換機構の動作開始時期に時間差をもたせたことを特徴とする請求項２に記載の火花点火式エンジンの制御装置。 The valve mechanism of the intake and exhaust valves provided in each cylinder is provided with a switching mechanism that switches the gas flow path by changing each valve between an activated state and a stopped state, and supplies and discharges hydraulic pressure to the switching mechanism. 3. A plurality of control members that change each of the valves between an operating state and a stopped state by controlling, and having a time difference in operation start timing of the switching mechanism by the control members. Spark ignition engine control device.
JP2003339992A 2003-09-30 2003-09-30 Control device for spark ignition engine Expired - Fee Related JP4158670B2 (en)

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