JP4654977B2 - Internal combustion engine - Google Patents

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JP4654977B2
JP4654977B2 JP2006149145A JP2006149145A JP4654977B2 JP 4654977 B2 JP4654977 B2 JP 4654977B2 JP 2006149145 A JP2006149145 A JP 2006149145A JP 2006149145 A JP2006149145 A JP 2006149145A JP 4654977 B2 JP4654977 B2 JP 4654977B2
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valve
internal combustion
combustion engine
flow path
exhaust
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JP2007321560A (en
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俊輔 山名
先基 李
健一 佐藤
公良 西沢
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Nissan Motor Co Ltd
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    • Y—GENERAL 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
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Description

本発明は、本発明は、排気系の比較的上流に触媒コンバータを備えたバイパス流路側に流路切換弁により排気を案内するようにした内燃機関に関する。   The present invention relates to an internal combustion engine in which exhaust gas is guided by a flow path switching valve to a bypass flow path side provided with a catalytic converter relatively upstream of an exhaust system.

従来から知られているように、車両の床下などの排気系の比較的下流側にメイン触媒コンバータを配置した構成では、内燃機関の冷間始動後、触媒コンバータの温度が上昇して活性化するまでの間、十分な排気浄化作用を期待することができない。また一方、触媒コンバータを排気系の上流側つまり内燃機関側に近付けるほど、触媒の熱劣化による耐久性低下が問題となる。   As conventionally known, in a configuration in which the main catalytic converter is disposed relatively downstream of the exhaust system such as under the floor of a vehicle, the temperature of the catalytic converter rises and is activated after a cold start of the internal combustion engine. In the meantime, a sufficient exhaust purification action cannot be expected. On the other hand, the closer the catalytic converter is to the upstream side of the exhaust system, that is, the internal combustion engine side, the lower the durability due to thermal degradation of the catalyst.

そのため、特許文献１に開示されているように、メイン触媒コンバータを備えたメイン流路の上流側部分と並列にバイパス流路を設けるとともに、このバイパス流路に、別のバイパス触媒コンバータを介装し、両者を切り換える切換弁によって、冷間始動直後は、バイパス流路側に排気を案内するようにした排気装置が、従来から提案されている。この構成では、バイパス触媒コンバータは排気系の中でメイン触媒コンバータよりも相対的に上流側に位置しており、相対的に早期に活性化するので、より早い段階から排気浄化を開始することができる。
特開平５−３２１６４４号公報 Therefore, as disclosed in Patent Document 1, a bypass flow path is provided in parallel with the upstream portion of the main flow path including the main catalytic converter, and another bypass catalytic converter is interposed in the bypass flow path. However, an exhaust device has been conventionally proposed in which exhaust gas is guided to the bypass flow path side immediately after the cold start by a switching valve for switching between the two. In this configuration, the bypass catalytic converter is positioned relatively upstream of the main catalytic converter in the exhaust system and is activated relatively early, so that exhaust purification can be started from an earlier stage. it can.
JP-A-5-321644

しかしながら上記のような構成においては、メイン触媒コンバータの暖機が完了してメイン流路側へ排気が流れるように切換弁が切り換えられたときに、通路抵抗となるバイパス触媒コンバータを通らずに排気が流れることから、排圧が急激に低下し、トルク段差（具体的にはトルクの上昇）が発生する。   However, in the configuration as described above, when the changeover valve is switched so that the warm-up of the main catalytic converter is completed and the exhaust flows to the main flow path side, the exhaust does not pass through the bypass catalytic converter that becomes a passage resistance. As a result of the flow, the exhaust pressure rapidly decreases and a torque step (specifically, an increase in torque) occurs.

そこで、本発明は、メイン触媒コンバータを下流側に備えたメイン通路の上流側部分と並列に総断面積が上記メイン通路の総断面積と比べて相対的に小さいバイパス通路が設けられると共に、このバイパス通路にバイパス触媒コンバータを備え、かつ上記メイン通路のうち上記バイパス通路のバイパスされる上記上流側部分に該メイン通路を閉塞する流路切換弁を備えてなる内燃機関において、
上記流路切換弁が閉状態から開状態へ切り換わる際に排気弁閉時期と吸気弁開時期とのバルブオーバーラップ量がある場合には、上記流路切換弁の開弁動作に先立って、上記バルブオーバーラップ量を漸次減少させることを特徴としている。これによって、気筒内の残留ガス量が減少し、流路切換弁が閉状態から開状態へ切り換わる際に排圧が減少しても気筒内の残留ガス量が急激に減少することはない。 Accordingly, the present invention is provided with a bypass passage having a relatively small total cross-sectional area compared to the total cross-sectional area of the main passage in parallel with the upstream portion of the main passage provided with the main catalytic converter on the downstream side. In an internal combustion engine comprising a bypass catalytic converter in a bypass passage and a flow path switching valve for closing the main passage in the upstream portion of the main passage that is bypassed by the bypass passage,
When there is a valve overlap amount between the exhaust valve closing timing and the intake valve opening timing when the flow path switching valve is switched from the closed state to the open state, prior to the opening operation of the flow path switching valve, The valve overlap amount is gradually reduced. As a result, the amount of residual gas in the cylinder decreases, and the amount of residual gas in the cylinder does not rapidly decrease even if the exhaust pressure decreases when the flow path switching valve switches from the closed state to the open state.

本発明によれば、流路切換弁が閉状態から開状態へ切り換わる際に、気筒内の残留ガス量が新気に置き換わることで相対的に吸入効率が上昇してしまうことを防止することができ、トルク段差のない平坦な特性の内燃機関の発生トルクを得ることができる。   According to the present invention, when the flow path switching valve is switched from the closed state to the open state, it is possible to prevent the suction efficiency from being relatively increased by replacing the residual gas amount in the cylinder with fresh air. Thus, the torque generated by the internal combustion engine having a flat characteristic without a torque step can be obtained.

以下、この発明を直列４気筒内燃機関の排気装置として適用した一実施形態を図面に基づいて詳細に説明する。   Hereinafter, an embodiment in which the present invention is applied as an exhaust device of an in-line four-cylinder internal combustion engine will be described in detail with reference to the drawings.

図１は、この排気装置の配管レイアウトを模式的に示した説明図であり、始めに、この図１に基づいて、排気装置全体の構成を説明する。   FIG. 1 is an explanatory view schematically showing the piping layout of the exhaust device. First, the configuration of the entire exhaust device will be described based on FIG.

シリンダヘッド１には、直列に配置された♯１気筒〜♯４気筒の各気筒の排気ポート２がそれぞれ側面に向かって開口するように形成されており、この排気ポート２のそれぞれに、メイン通路３が接続されている。♯１気筒〜♯４気筒の４本のメイン通路３は、１本の流路に合流しており、その下流側に、メイン触媒コンバータ４が配置されている。このメイン触媒コンバータ４は、車両の床下に配置される容量の大きなものであって、触媒としては、例えば、三元触媒とＨＣトラップ触媒とを含んでいる。上記のメイン通路３およびメイン触媒コンバータ４によって、通常の運転時に排気が通流するメイン流路が構成される。また、各気筒からの４本のメイン通路３の合流点には、流路切換手段として各メイン通路３を一斉に開閉する流路切換弁５が設けられている。   In the cylinder head 1, exhaust ports 2 of the cylinders # 1 to # 4 arranged in series are formed so as to open toward the side surfaces, and a main passage is formed in each of the exhaust ports 2. 3 is connected. The four main passages 3 of the # 1 cylinder to the # 4 cylinder merge into one flow path, and the main catalytic converter 4 is disposed on the downstream side thereof. The main catalytic converter 4 has a large capacity arranged under the floor of the vehicle, and includes, for example, a three-way catalyst and an HC trap catalyst as the catalyst. The main passage 3 and the main catalytic converter 4 constitute a main passage through which exhaust flows during normal operation. In addition, a flow path switching valve 5 that opens and closes the main passages 3 at the same time is provided as a flow path switching means at the junction of the four main paths 3 from each cylinder.

一方、バイパス流路として、各気筒のメイン通路３の各々から、該メイン通路３よりも通路断面積の小さなバイパス通路７がそれぞれ分岐している。各バイパス通路７の上流端となる分岐点６は、メイン通路３のできるだけ上流側の位置に設定されている。４本のバイパス通路７は、下流側で１本の流路に合流しており、その合流点の直後に、三元触媒を用いたバイパス触媒コンバータ８が介装されている。このバイパス触媒コンバータ８は、メイン触媒コンバータ４に比べて容量が小さな小型のものであり、望ましくは、低温活性に優れた触媒が用いられる。バイパス触媒コンバータ８の出口側から延びるバイパス通路７の下流端は、メイン通路３におけるメイン触媒コンバータ４上流側に合流点１２において（流路切換弁５が合流点１２より上流側となるように）接続されている。   On the other hand, bypass passages 7 each having a smaller passage sectional area than the main passage 3 are branched from the main passages 3 of the respective cylinders as bypass passages. The branch point 6 that is the upstream end of each bypass passage 7 is set to a position on the upstream side of the main passage 3 as much as possible. The four bypass passages 7 merge into one flow path on the downstream side, and a bypass catalytic converter 8 using a three-way catalyst is interposed immediately after the junction. The bypass catalytic converter 8 has a small capacity as compared with the main catalytic converter 4 and desirably uses a catalyst excellent in low temperature activity. The downstream end of the bypass passage 7 extending from the outlet side of the bypass catalytic converter 8 is at the junction 12 on the upstream side of the main catalyst converter 4 in the main passage 3 (so that the flow path switching valve 5 is upstream of the junction 12). It is connected.

尚、メイン触媒コンバータ４の入口部およびバイパス触媒コンバータ８の入口部には、それぞれ空燃比センサ１０，１１が配置されている。   Air-fuel ratio sensors 10 and 11 are disposed at the inlet of the main catalytic converter 4 and the inlet of the bypass catalytic converter 8, respectively.

また、本実施形態において、排気弁（図示せず）を駆動する排気弁側動弁機構は、図示せぬ排気弁側カムシャフトの前端部に設けられた図示せぬ排気弁側スプロケットと、この排気弁側スプロケットと上記排気弁側カムシャフトとを所定の角度範囲内において相対的に回転させる図示せぬ排気弁側位相制御用アクチュエータと、から構成され、上記排気弁側スプロケットは、図示せぬタイミングチェーンもしくはタイミングベルトを介して、図示せぬクランクシャフトに連動している。   In this embodiment, an exhaust valve side valve operating mechanism for driving an exhaust valve (not shown) includes an exhaust valve side sprocket (not shown) provided at the front end of an exhaust valve side camshaft (not shown), An exhaust valve side sprocket and an exhaust valve side phase control actuator (not shown) for relatively rotating the exhaust valve side sprocket and the exhaust valve side camshaft within a predetermined angle range. The exhaust valve side sprocket is not shown. It is linked to a crankshaft (not shown) via a timing chain or a timing belt.

また、吸気弁を駆動する吸気弁側動弁機構は、図示せぬ吸気弁側カムシャフトの前端部に設けられた図示せぬ吸気弁側スプロケットと、この吸気弁側スプロケットと上記吸気弁側カムシャフトとを所定の角度範囲内において相対的に回転させる図示せぬ吸気弁側位相制御用アクチュエータと、から構成され、上記吸気弁側スプロケットは、図示せぬタイミングチェーンもしくはタイミングベルトを介して、図示せぬクランクシャフトに連動している。   The intake valve side valve operating mechanism for driving the intake valve includes an intake valve side sprocket (not shown) provided at a front end portion of an intake valve side camshaft (not shown), the intake valve side sprocket, and the intake valve side cam. An intake valve side phase control actuator (not shown) that relatively rotates the shaft within a predetermined angle range, and the intake valve side sprocket is connected via a timing chain or a timing belt (not shown). It is linked to a crankshaft not shown.

上記排気弁側位相制御用アクチュエータ及び上記吸気弁側位相制御用アクチュエータは、例えば油圧式の回転型アクチュエータからなっている。そして、この排気弁側位相制御用アクチュエータの作用によって、上記排気弁側スプロケットと上記排気弁側カムシャフトとが相対的に回転し、排気弁のバルブリフトにおけるリフト中心角が遅進する。同様に、吸気弁側位相制御用アクチュエータの作用によって、上記吸気弁側スプロケットと上記吸気弁側カムシャフトとが相対的に回転し、吸気弁のバルブリフトにおけるリフト中心角が遅進する。つまり、上記排気弁側位相制御用アクチュエータ及び上記吸気弁側位相制御用アクチュエータの作用によって、排気弁及び吸気弁のそれぞれのリフト特性の曲線自体は変わらずに、全体が連続的に進角もしくは遅角する。   The exhaust valve side phase control actuator and the intake valve side phase control actuator are, for example, hydraulic rotary actuators. The exhaust valve side sprocket and the exhaust valve side camshaft rotate relatively by the action of the exhaust valve side phase control actuator, and the lift center angle in the valve lift of the exhaust valve is retarded. Similarly, by the action of the intake valve side phase control actuator, the intake valve side sprocket and the intake valve side camshaft rotate relatively, and the lift center angle in the valve lift of the intake valve is retarded. In other words, due to the action of the exhaust valve side phase control actuator and the intake valve side phase control actuator, the lift characteristics curves of the exhaust valve and the intake valve do not change, and the whole is continuously advanced or retarded. Horn.

このような構成において、冷間始動後の機関温度ないしは排気温度が低い段階では、適宜なアクチュエータを介して流路切換弁５が閉じられ、メイン通路３が遮断される。そのため、各気筒から吐出された排気は、その全量が分岐点６からバイパス通路７を通してバイパス触媒コンバータ８へと流れる。バイパス触媒コンバータ８は、排気系の上流側つまり排気ポート２に近い位置にあり、かつ小型のものであるので、速やかに活性化し、早期に排気浄化が開始される。   In such a configuration, when the engine temperature or the exhaust gas temperature after the cold start is low, the flow path switching valve 5 is closed via an appropriate actuator, and the main passage 3 is blocked. Therefore, the entire amount of exhaust discharged from each cylinder flows from the branch point 6 to the bypass catalytic converter 8 through the bypass passage 7. The bypass catalytic converter 8 is located upstream of the exhaust system, that is, at a position close to the exhaust port 2 and is small in size, so that it is activated quickly and exhaust purification is started at an early stage.

一方、機関の暖機が進行して、機関温度ないしは排気温度が十分に高くなったら、流路切換弁５が開放される。これにより、各気筒から吐出された排気は、主に、メイン通路３からメイン触媒コンバータ４を通過する。このときバイパス通路７側は特に遮断されていないが、バイパス通路７側の方がメイン通路３側よりも通路断面積が小さく、かつバイパス触媒コンバータ８が介在しているので、両者の通路抵抗の差により、排気流の大部分はメイン通路３側を通り、バイパス通路７側には殆ど流れない。従って、バイパス触媒コンバータ８の熱劣化は十分に抑制される。   On the other hand, when the engine warms up and the engine temperature or the exhaust temperature becomes sufficiently high, the flow path switching valve 5 is opened. Thus, the exhaust discharged from each cylinder mainly passes through the main catalytic converter 4 from the main passage 3. At this time, the bypass passage 7 side is not particularly cut off, but the bypass passage 7 side has a smaller passage cross-sectional area than the main passage 3 side and the bypass catalytic converter 8 is interposed. Due to the difference, most of the exhaust flow passes through the main passage 3 side and hardly flows into the bypass passage 7 side. Therefore, the thermal deterioration of the bypass catalytic converter 8 is sufficiently suppressed.

ここで、上記のように流路切換弁５がメイン通路３を開放したときに、メイン通路３の通路抵抗が小さいことから、排圧が急激に低下し、気筒内の残留ガス量も急激に減少する。このとき気筒内においては、残留ガスの減少分が新気に置き換わることになり、相対的に吸入効率が上昇し、瞬間的にトルクが上昇してトルク段差が発生することになる。   Here, when the flow path switching valve 5 opens the main passage 3 as described above, since the passage resistance of the main passage 3 is small, the exhaust pressure rapidly decreases, and the residual gas amount in the cylinder also sharply increases. Decrease. At this time, in the cylinder, the decrease in the residual gas is replaced with fresh air, the suction efficiency is relatively increased, the torque is instantaneously increased, and a torque step is generated.

そこで、この発明では、流路切換弁５が開くときに排気弁閉時期と吸気弁開時期とのバルブオーバーラップ量（Ｏ／Ｌ量）がある場合に、予めこのバルブオーバーラップ量を減少させ、気筒内の残留ガス量を減少させておくことで、メイン通路３内の圧力降下が急激に起こり気筒内の残流ガス量が新気に置き換わることで生じる瞬間的なトルクの上昇を防止する。   Therefore, in the present invention, when there is a valve overlap amount (O / L amount) between the exhaust valve closing timing and the intake valve opening timing when the flow path switching valve 5 is opened, the valve overlap amount is reduced in advance. By reducing the residual gas amount in the cylinder, an instantaneous torque increase caused by a rapid pressure drop in the main passage 3 and the residual gas amount in the cylinder being replaced with fresh air is prevented. .

図２は、本発明の第１実施形態における種々の動作を説明するためのタイミングチャートを示している。   FIG. 2 shows a timing chart for explaining various operations in the first embodiment of the present invention.

暖機が完了した段階で流路切換弁５に対する制御指令が全閉指令から全開指令に切り換わると、流路切換弁５の実際の開弁動作に先立って、気筒内の残留ガス量を減少させるべく、排気弁閉時期と吸気弁開時期とのバルブオーバーラップ量を漸次減少させると共に、吸気通路に配置されたスロットル弁（図示せず）の弁開度を漸次減少させることで（筒内の新気量を概ね一定に保ち）、トルク変動を抑制する。このとき、気筒内の残留ガス量が予め設定された所定値（残留ガス基準値）となるように上記バルブオーバーラップ量を漸次減少させる。このバルブオーバーラップ量を減少させる方法としては、吸気弁の開時期は固定して排気弁の閉時期のみを上述の排気弁側位相制御用アクチュエータの作用によって進角させてもよいし、排気弁の閉時期は固定して吸気弁に開時期のみを上述の吸気弁側位相制御用アクチュエータの作用によってリタード（遅角）させるようにしてもよい。あるいは排気弁閉時期を進角させると共に、吸気弁開時期を遅角させることで上記バルブオーバーラップ量を漸次減少させてることも可能である。そして、気筒内の残留ガス量を上記残留ガス基準値まで減少させてから、流路切換弁５を開き始める。   When the control command for the flow path switching valve 5 is switched from the fully closed command to the full open command when the warm-up is completed, the residual gas amount in the cylinder is reduced prior to the actual opening operation of the flow path switching valve 5. In order to achieve this, the valve overlap amount between the exhaust valve closing timing and the intake valve opening timing is gradually decreased, and the opening degree of a throttle valve (not shown) disposed in the intake passage is gradually decreased (in-cylinder The air volume of the air is kept almost constant) and torque fluctuations are suppressed. At this time, the valve overlap amount is gradually decreased so that the residual gas amount in the cylinder becomes a predetermined value (residual gas reference value) set in advance. As a method of reducing the valve overlap amount, the intake valve opening timing may be fixed, and only the exhaust valve closing timing may be advanced by the action of the exhaust valve side phase control actuator. The closing timing may be fixed and only the opening timing of the intake valve may be retarded (retarded) by the action of the intake valve side phase control actuator. Alternatively, it is possible to gradually decrease the valve overlap amount by advancing the exhaust valve closing timing and retarding the intake valve opening timing. Then, after the residual gas amount in the cylinder is reduced to the residual gas reference value, the flow path switching valve 5 starts to open.

これにより、流路切換弁５が全閉状態から開き始める際には、気筒内の残留ガス量は減少しており、流路切換弁５が開き始めて排圧が減少しても気筒内の残留ガス量が急激に減少することはない。つまり、気筒内の残留ガス量が新気に置き換わることで相対的に吸入効率が上昇してしまうことを防止することができ、トルク段差のない平坦な特性の内燃機関の発生トルクを得ることができる。   Thereby, when the flow path switching valve 5 starts to open from the fully closed state, the residual gas amount in the cylinder decreases, and even if the flow path switching valve 5 starts to open and the exhaust pressure decreases, the residual gas in the cylinder remains. The amount of gas does not decrease rapidly. In other words, it is possible to prevent the intake efficiency from being relatively increased by replacing the residual gas amount in the cylinder with fresh air, and to obtain the generated torque of the internal combustion engine having a flat characteristic without a torque step. it can.

換言すれば、流路切換弁５が開弁する際に、気筒内の残留ガス量が急激に減少することによる空燃比変動（Ａ／Ｆ変動）を抑制することができ、この空燃比変動に起因するトルク段差を防止することができると共に、排気性能悪化を抑制することができる。   In other words, when the flow path switching valve 5 is opened, the air-fuel ratio fluctuation (A / F fluctuation) due to the sudden decrease in the residual gas amount in the cylinder can be suppressed. The resulting torque step can be prevented and exhaust performance deterioration can be suppressed.

さらに、上記バルブオーバーラップ量を減少させることにより気筒内の残留ガス量をコントロールすることで、流路切換弁５のバルブ開閉速度（切り換え速度）に影響されることなく気筒内の残留ガス量をコントロールすることが可能となるため、例えば、バルブ開閉速度がコントロールができない駆動方式のアクチュエータを流路切換弁５の駆動源として採用することが可能となり、流路切換弁５の駆動源となるアクチュエータの選択の自由度が大きくなり、コスト低減を図ることができる。   Furthermore, by controlling the residual gas amount in the cylinder by reducing the valve overlap amount, the residual gas amount in the cylinder can be reduced without being affected by the valve opening / closing speed (switching speed) of the flow path switching valve 5. Since it becomes possible to control, for example, an actuator of a drive system in which the valve opening / closing speed cannot be controlled can be adopted as a drive source of the flow path switching valve 5, and an actuator that becomes a drive source of the flow path switching valve 5 The degree of freedom of selection increases, and the cost can be reduced.

そして、流路切換弁５が全開状態となると、上記バルブオーバーラップ量を流路切換弁５に全開指令がでる前の状態まで漸次増加させると共に、上記スロットル弁の弁開度を、流路切換弁５に全開指令がでる前の状態よりも小さい弁開度まで漸次増加させる。このように、上記バルブオーバーラップ量を漸次増加させる際に、上記スロットル弁の弁開度も漸次増加させることで、上記バルブオーバーラップ量を流路切換弁５の切り換え前の状態に戻す際のトルク変動を抑制することができる。   When the flow path switching valve 5 is fully opened, the valve overlap amount is gradually increased to a state before a full open command is issued to the flow path switching valve 5, and the valve opening of the throttle valve is changed to flow path switching. The valve 5 is gradually increased to a valve opening smaller than the state before the fully open command is issued to the valve 5. As described above, when the valve overlap amount is gradually increased, the valve opening amount of the throttle valve is also gradually increased to return the valve overlap amount to the state before the switching of the flow path switching valve 5. Torque fluctuation can be suppressed.

尚、図２において、破線で示すＡ／Ｆは、気筒内の残留ガス量が急激に減少した（新気に置き換わる）場合を示している。また、図２において、破線で示す発生トルクは、Ａ／Ｆが図２に破線で示すＡ／Ｆの場合を示している。   In FIG. 2, A / F indicated by a broken line indicates a case where the amount of residual gas in the cylinder has rapidly decreased (replaced with fresh air). In FIG. 2, the generated torque indicated by a broken line indicates a case where A / F is A / F indicated by a broken line in FIG. 2.

図３は、本発明の第２実施形態における種々の動作を説明するためのタイミングチャートを示している。   FIG. 3 shows a timing chart for explaining various operations in the second embodiment of the present invention.

この第２実施形態は、上述した第１実施形態と略同様に制御されているが、外部ＥＧＲを吸気系に還流するＥＧＲ手段としての排気還流装置（図示せず）を有し、上述した分岐点６より上流側から取り込んだ排気ガスの一部を流量を制御しつつ吸気系に還流させている。   This second embodiment is controlled in substantially the same manner as the first embodiment described above, but has an exhaust gas recirculation device (not shown) as EGR means for returning the external EGR to the intake system, and the above-described branching is performed. Part of the exhaust gas taken from the upstream side of the point 6 is recirculated to the intake system while controlling the flow rate.

詳述すると、暖機が完了した段階で流路切換弁５に対する制御指令が全閉指令から全開指令に切り換わると、流路切換弁５の実際の開弁動作に先立って、気筒内の残留ガス量を減少させるべく、排気弁閉時期と吸気弁開時期とのバルブオーバーラップ量を漸次減少させると共に、吸気通路に配置されたスロットル弁（図示せず）の弁開度を漸次減少させ、さらに上記排気還流装置により外部ＥＧＲ率が漸次減少させている。   More specifically, when the control command for the flow path switching valve 5 is switched from the fully closed command to the fully open command at the stage where the warm-up is completed, the residual in the cylinder is prior to the actual opening operation of the flow path switching valve 5. In order to reduce the gas amount, the valve overlap amount between the exhaust valve closing timing and the intake valve opening timing is gradually decreased, and the opening degree of a throttle valve (not shown) disposed in the intake passage is gradually decreased. Further, the external EGR rate is gradually reduced by the exhaust gas recirculation device.

尚、図３中において、破線で示すＡ／Ｆは、上記外部ＥＧＲ率を上記バルブオーバーラップ量及びスロットル弁の開度と伴に漸次減少させなかった場合を示している。また、図３において、破線で示す発生トルクは、Ａ／Ｆが図３に破線で示すＡ／Ｆの場合を示している。   In FIG. 3, A / F indicated by a broken line indicates a case where the external EGR rate is not gradually decreased along with the valve overlap amount and the opening degree of the throttle valve. Further, in FIG. 3, the generated torque indicated by a broken line indicates a case where A / F is A / F indicated by a broken line in FIG.

このような第２実施形態においても、上述した第１実施形態と同様の作用効果を得ることができる。   In such a second embodiment, the same operational effects as those of the first embodiment described above can be obtained.

尚、上述した各実施形態においては、流路切換弁５を全閉状態から全開状態に切り換えた際の排圧変化が、排気行程の時の抵抗変化となる虞が僅かながらあるので、流路切換弁５を全閉状態から全開状態に切り換える際に、上記スロットル弁の弁開度を少しづつ減少するようにしてもよい。   In each of the above-described embodiments, there is a slight possibility that a change in exhaust pressure when the flow path switching valve 5 is switched from the fully closed state to the fully open state may become a resistance change during the exhaust stroke. When the switching valve 5 is switched from the fully closed state to the fully opened state, the opening degree of the throttle valve may be gradually decreased.

また、気筒内の残留ガス量が上記残留ガス基準値となるまで上記バルブオーバーラップ量を減少させるのではなく、排気弁閉時期と吸気弁開時期とが一致するまで、または排気弁閉時期が吸気弁開時期よりも相対的に進角した状態まで、排気弁閉時期あるいは吸気弁開時期の少なくとも一方を変更するようにしてもよい。   In addition, the valve overlap amount is not decreased until the residual gas amount in the cylinder reaches the residual gas reference value, but the exhaust valve closing timing coincides with the intake valve opening timing or the exhaust valve closing timing is At least one of the exhaust valve closing timing and the intake valve opening timing may be changed to a state in which the angle is relatively advanced with respect to the intake valve opening timing.

上記実施形態から把握し得る本発明の技術的思想について、その効果とともに列記する。   The technical idea of the present invention that can be grasped from the above embodiment will be listed together with the effects thereof.

（１） メイン触媒コンバータを下流側に備えたメイン通路の上流側部分と並列に総断面積が上記メイン通路の総断面積と比べて相対的に小さいバイパス通路が設けられると共に、このバイパス通路にバイパス触媒コンバータを備え、かつ上記メイン通路のうち上記バイパス通路のバイパスされる上記上流側部分に該メイン通路を閉塞する流路切換弁を備えてなる内燃機関において、上記流路切換弁が閉状態から開状態へ切り換わる際に排気弁閉時期と吸気弁開時期とのバルブオーバーラップ量がある場合には、上記流路切換弁の開弁動作に先立って、上記バルブオーバーラップ量を漸次減少させる。これによって、気筒内の残留ガス量が減少し、流路切換弁が閉状態から開状態へ切り換わる際に排圧が減少しても気筒内の残留ガス量が急激に減少することはない。つまり、流路切換弁が閉状態から開状態へ切り換わる際に、気筒内の残留ガス量が新気に置き換わることで相対的に吸入効率が上昇してしまうことを防止することができ、トルク段差のない平坦な特性の内燃機関の発生トルクを得ることができる。   (1) A bypass passage having a relatively small total cross-sectional area compared to the total cross-sectional area of the main passage is provided in parallel with the upstream portion of the main passage provided with the main catalytic converter on the downstream side. An internal combustion engine comprising a bypass catalytic converter and having a flow path switching valve that closes the main passage in the upstream portion of the main passage that is bypassed by the bypass passage, wherein the flow path switching valve is in a closed state If there is a valve overlap amount between the exhaust valve closing timing and the intake valve opening timing when switching from the open state to the open state, the valve overlap amount is gradually reduced prior to the opening operation of the flow path switching valve. Let As a result, the amount of residual gas in the cylinder decreases, and the amount of residual gas in the cylinder does not rapidly decrease even if the exhaust pressure decreases when the flow path switching valve switches from the closed state to the open state. That is, when the flow path switching valve is switched from the closed state to the open state, it is possible to prevent the suction efficiency from being relatively increased by replacing the residual gas amount in the cylinder with the fresh air, and the torque. The generated torque of the internal combustion engine having a flat characteristic without a step can be obtained.

（２） 上記（１）に記載の内燃機関は、具体的には、吸気弁開時期をリタードすることにより上記バルブオーバーラップ量を減少させる。   (2) Specifically, the internal combustion engine according to (1) reduces the valve overlap amount by retarding the intake valve opening timing.

（３） 上記（１）に記載の内燃機関は、具体的には、排気弁閉時期を進角させることにより上記バルブオーバーラップ量を減少させる。   (3) The internal combustion engine described in (1) specifically reduces the valve overlap amount by advancing the exhaust valve closing timing.

（４） 上記（３）に記載の内燃機関は、具体的には、排気弁閉時期は、吸気弁開時期と一致させるか吸気弁開時期よりも相対的に進角した状態まで進角させる。   (4) In the internal combustion engine described in (3) above, specifically, the exhaust valve closing timing is advanced to a state where the exhaust valve closing timing coincides with the intake valve opening timing or is advanced relative to the intake valve opening timing. .

（５） 上記（１）〜（４）のいずれかに記載の内燃機関は、具体的には、上記バルブオーバーラップ量を漸次減少させる際に、スロットル弁の弁開度を漸次減少させる。   (5) Specifically, the internal combustion engine according to any one of the above (1) to (4) gradually decreases the valve opening of the throttle valve when the valve overlap amount is gradually decreased.

（６） 上記（１）〜（５）のいずれかに記載の内燃機関は、排気ガスの一部を流量を制御しつつ吸気系に還流させるＥＧＲ手段を備え、上記流路切換弁が閉状態から開状態へ切り換わる際に上記ＥＧＲ手段により吸気系に外部ＥＧＲが還流している場合には、上記流路切換弁の開弁動作に先立って、外部ＥＧＲ率を漸次減少させる。   (6) The internal combustion engine according to any one of the above (1) to (5) includes EGR means for recirculating a part of the exhaust gas to the intake system while controlling the flow rate, and the flow path switching valve is closed. When the external EGR is recirculated to the intake system by the EGR means when switching from the open state to the open state, the external EGR rate is gradually reduced prior to the opening operation of the flow path switching valve.

（７） 上記（６）に記載の内燃機関は、具体的には、上記バルブオーバーラップ量を漸次減少させる際に、外部ＥＧＲ率を漸次減少させると共に、スロットル弁の弁開度を漸次減少させる。   (7) Specifically, the internal combustion engine according to (6) described above gradually decreases the external EGR rate and gradually decreases the valve opening of the throttle valve when the valve overlap amount is gradually decreased. .

（８） 上記（１）〜（７）のいずれかに記載の内燃機関は、上記バイパスバルブが閉状態から開状態に切り換わると、上記バルブオーバーラップ量が上記流路切換弁を閉状態から開状態へ切り換える前のバルブオーバーラップ量となるなるまで漸次増加させると共に、スロットル弁の弁開度を漸次増加させる。これによって、バルブオーバーラップ量を増加させる際のトルク変動を抑制することができる。   (8) In the internal combustion engine according to any one of the above (1) to (7), when the bypass valve is switched from the closed state to the open state, the valve overlap amount is changed from the closed state to the flow path switching valve. While gradually increasing until the valve overlap amount before switching to the open state, the valve opening of the throttle valve is gradually increased. Thereby, torque fluctuations when increasing the valve overlap amount can be suppressed.

本発明に係る内燃機関の排気装置の全体の配管レイアウトを示す構成説明図。BRIEF DESCRIPTION OF THE DRAWINGS Configuration explanatory drawing which shows the piping layout of the whole exhaust apparatus of the internal combustion engine which concerns on this invention. 本発明の第１実施形態における種々の動作を説明するためのタイミングチャート。The timing chart for demonstrating the various operation | movement in 1st Embodiment of this invention. 本発明の第２実施形態における種々の動作を説明するためのタイミングチャート。The timing chart for demonstrating the various operation | movement in 2nd Embodiment of this invention.

符号の説明Explanation of symbols

３…メイン通路
４…メイン触媒コンバータ
５…流路切換弁
６…分岐点
７…バイパス通路
８…バイパス触媒コンバータ
１２…合流点 DESCRIPTION OF SYMBOLS 3 ... Main passage 4 ... Main catalytic converter 5 ... Flow path switching valve 6 ... Branch point 7 ... Bypass passage 8 ... Bypass catalytic converter 12 ... Junction point

Claims (8)

メイン触媒コンバータを下流側に備えたメイン通路の上流側部分と並列に総断面積が上記メイン通路の総断面積と比べて相対的に小さいバイパス通路が設けられると共に、このバイパス通路にバイパス触媒コンバータを備え、かつ上記メイン通路のうち上記バイパス通路のバイパスされる上記上流側部分に該メイン通路を閉塞する流路切換弁を備えてなる内燃機関において、
上記流路切換弁が閉状態から開状態へ切り換わる際に排気弁閉時期と吸気弁開時期とのバルブオーバーラップ量がある場合には、上記流路切換弁の開弁動作に先立って、上記バルブオーバーラップ量を漸次減少させることを特徴とする内燃機関。 A bypass passage having a smaller overall cross-sectional area than the total cross-sectional area of the main passage is provided in parallel with the upstream portion of the main passage provided with the main catalytic converter on the downstream side. And an internal combustion engine comprising a flow path switching valve that closes the main passage in the upstream portion of the main passage that is bypassed by the bypass passage,
When there is a valve overlap amount between the exhaust valve closing timing and the intake valve opening timing when the flow path switching valve is switched from the closed state to the open state, prior to the opening operation of the flow path switching valve, An internal combustion engine characterized by gradually reducing the valve overlap amount. 吸気弁開時期をリタードすることにより上記バルブオーバーラップ量を減少させることを特徴とする請求項１に記載の内燃機関。   The internal combustion engine according to claim 1, wherein the valve overlap amount is reduced by retarding an intake valve opening timing. 排気弁閉時期を進角させることにより上記バルブオーバーラップ量を減少させることを特徴とする請求項１に記載の内燃機関。   The internal combustion engine according to claim 1, wherein the valve overlap amount is reduced by advancing the exhaust valve closing timing. 排気弁閉時期は、吸気弁開時期と一致させるか吸気弁開時期よりも相対的に進角した状態まで進角させることを特徴とする請求項３に記載の内燃機関。   The internal combustion engine according to claim 3, wherein the exhaust valve closing timing is made to coincide with the intake valve opening timing or advanced to a state where the exhaust valve closing timing is relatively advanced with respect to the intake valve opening timing. 上記バルブオーバーラップ量を漸次減少させる際に、スロットル弁の弁開度を漸次減少させることを特徴とする請求項１〜４のいずれかに記載の内燃機関。   The internal combustion engine according to any one of claims 1 to 4, wherein when the valve overlap amount is gradually decreased, the valve opening of the throttle valve is gradually decreased. 排気ガスの一部を流量を制御しつつ吸気系に還流させるＥＧＲ手段を備え、上記流路切換弁が閉状態から開状態へ切り換わる際に上記ＥＧＲ手段により吸気系に外部ＥＧＲが還流している場合には、上記流路切換弁の開弁動作に先立って、外部ＥＧＲ率を漸次減少させることを特徴とする請求項１〜５のいずれかに記載の内燃機関。   EGR means for returning a part of the exhaust gas to the intake system while controlling the flow rate is provided. When the flow path switching valve is switched from the closed state to the open state, the external EGR is returned to the intake system by the EGR means. 6. The internal combustion engine according to claim 1, wherein the external EGR rate is gradually reduced prior to the opening operation of the flow path switching valve. 上記バルブオーバーラップ量を漸次減少させる際に、外部ＥＧＲ率を漸次減少させると共に、スロットル弁の弁開度を漸次減少させることを特徴とする請求項６に記載の内燃機関。   The internal combustion engine according to claim 6, wherein when the valve overlap amount is gradually decreased, the external EGR rate is gradually decreased and the valve opening of the throttle valve is gradually decreased. 上記バイパスバルブが閉状態から開状態に切り換わると、上記バルブオーバーラップ量が上記流路切換弁を閉状態から開状態へ切り換える前のバルブオーバーラップ量となるなるまで漸次増加させると共に、スロットル弁の弁開度を漸次増加させることを特徴とする請求項１〜７のいずれかに記載の内燃機関。   When the bypass valve switches from the closed state to the open state, the valve overlap amount is gradually increased until the valve overlap amount becomes the valve overlap amount before switching the flow path switching valve from the closed state to the open state, and the throttle valve The internal combustion engine according to any one of claims 1 to 7, wherein the valve opening is gradually increased.
JP2006149145A 2006-05-29 2006-05-30 Internal combustion engine Expired - Fee Related JP4654977B2 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5479319A (en) * 1977-12-05 1979-06-25 Nissan Motor Co Ltd Device of warming up catalyst for automobile
JPH0579320A (en) * 1991-09-20 1993-03-30 Hitachi Ltd Internal combustion engine, operation thereof and automobile
JPH05321643A (en) * 1992-05-26 1993-12-07 Mazda Motor Corp Exhaust device of engine having turbo supercharger

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5479319A (en) * 1977-12-05 1979-06-25 Nissan Motor Co Ltd Device of warming up catalyst for automobile
JPH0579320A (en) * 1991-09-20 1993-03-30 Hitachi Ltd Internal combustion engine, operation thereof and automobile
JPH05321643A (en) * 1992-05-26 1993-12-07 Mazda Motor Corp Exhaust device of engine having turbo supercharger

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