JP2006299882A - Control device of internal combustion engine - Google Patents

Control device of internal combustion engine Download PDF

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JP2006299882A
JP2006299882A JP2005120865A JP2005120865A JP2006299882A JP 2006299882 A JP2006299882 A JP 2006299882A JP 2005120865 A JP2005120865 A JP 2005120865A JP 2005120865 A JP2005120865 A JP 2005120865A JP 2006299882 A JP2006299882 A JP 2006299882A
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combustion
fuel ratio
air
amount
supercharging pressure
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Hiroshi Tanaka
比呂志 田中
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Toyota Motor Corp
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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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    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
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    • Y02T10/12—Improving ICE efficiencies

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  • Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Supercharger (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device capable of preventing generation of a large torque shock when switching to second combustion from first combustion, in an internal combustion engine having a turbocharger and performed by switching the first combustion in the first air-fuel ratio on the leaner side than the theoretical air-fuel ratio and the second combustion in the second air-fuel ratio on the richer side than the first air-fuel ratio. <P>SOLUTION: This control device reduces throttle valve opening when switching (t1) to the second combustion in the second air-fuel ratio AF2 on the richer side than the first air-fuel ratio from the first combustion in the first air-fuel ratio AF1 on the leaner side than the theoretical air-fuel ratio AF2; and restrains an increase in supercharging pressure P by the turbocharger only for a preset period T. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、内燃機関の制御装置に関する。   The present invention relates to a control device for an internal combustion engine.

希薄燃焼と理論空燃比の通常燃焼とを切り換えて実施する内燃機関が公知である。このような内燃機関にターボチャージャを組み合わせた場合において、希薄燃焼時と通常燃焼時とでは、アクセルペダルの踏み込み変化に対する過給圧の応答遅れであるターボラグに違いが発生するために、それぞれのターボラグに基づき各燃焼時の燃料噴射量を補正することが提案されている（例えば、特許文献１参照）。   Internal combustion engines that perform switching between lean combustion and normal combustion at a stoichiometric air-fuel ratio are known. When a turbocharger is combined with such an internal combustion engine, a difference occurs in the turbo lag, which is a response delay of the boost pressure to the change in depression of the accelerator pedal, during lean combustion and normal combustion. Based on the above, it has been proposed to correct the fuel injection amount at the time of each combustion (see, for example, Patent Document 1).

特開平１１−３５１０４１号公報JP 11-351041 A 特開２００２−４８０３５号公報JP 2002-48035 A

前述の背景技術では、二つの燃焼の切り換え時に過給圧が変化することを考慮してスロットル弁開度及び燃料噴射量を制御することも開示されているが、このような制御だけでは、機関加速時において希薄燃焼から通常燃焼へ切り換えられる時に、大きなトルクショックの発生を防止することができない。   In the above-described background art, it is also disclosed that the throttle valve opening and the fuel injection amount are controlled in consideration of the change in the supercharging pressure when switching between the two combustion modes. When switching from lean combustion to normal combustion during acceleration, the occurrence of a large torque shock cannot be prevented.

希薄燃焼から通常燃焼に切り換えられる時に、スロットル弁開度は減少させられるが、吸気量は、徐々にしか減少せず、直ぐには切り換え時の通常燃焼に適した吸気量まで減少しない。このようにしか変化しない吸気量に対して、燃料噴射量は、希薄燃焼時のリーン空燃比から通常燃焼時の理論空燃比へ徐々に空燃比が変化するように排気ガスの空燃比状態に基づき制御される。   When switching from lean combustion to normal combustion, the throttle valve opening is decreased, but the intake air amount only decreases gradually, and does not immediately decrease to an intake air amount suitable for normal combustion at the time of switching. In contrast to the intake air amount that changes only in this way, the fuel injection amount is based on the air-fuel ratio state of the exhaust gas so that the air-fuel ratio gradually changes from the lean air-fuel ratio during lean combustion to the stoichiometric air-fuel ratio during normal combustion. Be controlled.

それにより、空燃比が理論空燃比へ近づくほどに排気ガス温度が上昇してターボチャージャのタービン効率が高められ、何もしなければ、ターボチャージャによる過給圧は急激に上昇する。こうして、スロットル弁開度を減少しているにも係わらずに、過給圧の上昇によって返って吸気量が増加することがあり、増加した吸気量に対して空燃比を理論空燃比へ近づけるように燃料噴射量が制御されると、エンジントルクは急激に高まり、大きなトルクショックが発生する。   As a result, the exhaust gas temperature rises as the air-fuel ratio approaches the stoichiometric air-fuel ratio, and the turbine efficiency of the turbocharger is increased. If nothing is done, the supercharging pressure by the turbocharger increases rapidly. Thus, although the throttle valve opening is decreased, the intake air amount may increase due to the increase in the boost pressure, and the air-fuel ratio is brought closer to the stoichiometric air-fuel ratio with respect to the increased intake air amount. When the fuel injection amount is controlled, the engine torque increases rapidly and a large torque shock occurs.

この問題は、希薄燃焼から理論空燃比の通常燃焼への切り換え時だけではなく、例えば、希薄燃焼から空燃比をリッチ側に変化させる場合（変化後の空燃比はリーン空燃比でも理論空燃比でもリッチ空燃比でも良い）に発生する。   This problem occurs not only when switching from lean combustion to stoichiometric air-fuel ratio normal combustion, but for example, when the air-fuel ratio is changed from lean combustion to the rich side (the air-fuel ratio after change is lean or stoichiometric). (It may be a rich air-fuel ratio).

従って、本発明の目的は、ターボチャージャを備えて、理論空燃比よりリーン側の第一空燃比での第一燃焼と、前記第一空燃比よりリッチ側の第二空燃比での第二燃焼とを切り換えて実施する内燃機関において、第一燃焼から第二燃焼へ切り換えられる時に大きなトルクショックの発生を防止可能とする制御装置を提供することである。   Accordingly, an object of the present invention is to provide a turbocharger, and perform first combustion at a first air-fuel ratio leaner than the stoichiometric air-fuel ratio and second combustion at a second air-fuel ratio richer than the first air-fuel ratio. In an internal combustion engine that performs switching between the first combustion and the second combustion, a control device that can prevent occurrence of a large torque shock when switching from the first combustion to the second combustion is provided.

本発明による請求項１に記載の内燃機関の制御装置は、ターボチャージャを備えて、理論空燃比よりリーン側の第一空燃比での第一燃焼と、前記第一空燃比よりリッチ側の第二空燃比での第二燃焼とを切り換えて実施する内燃機関において、前記第一燃焼から前記第二燃焼へ切り換えられる時には、スロットル弁開度を減少させると共に、設定期間の間だけ前記ターボチャージャによる過給圧の上昇を抑制することを特徴とする。   The control apparatus for an internal combustion engine according to claim 1 of the present invention includes a turbocharger, and performs first combustion at a first air-fuel ratio that is leaner than the stoichiometric air-fuel ratio and richer than the first air-fuel ratio. In an internal combustion engine that performs switching between the second combustion at the two air-fuel ratios and switching from the first combustion to the second combustion, the throttle valve opening is decreased and only by a turbocharger during a set period. It is characterized by suppressing an increase in supercharging pressure.

また、本発明による請求項２に記載の内燃機関の制御装置は、請求項１に記載の内燃機関の制御装置において、前記設定期間は、前記スロットル弁開度の減少によって吸気量が切り換え時の前記第二燃焼における目標吸気量となって前記第二空燃比での前記第二燃焼が実現されるまでの期間以上とすることを特徴とする。   According to a second aspect of the present invention, there is provided the control apparatus for an internal combustion engine according to the first aspect, wherein the intake air amount is changed during the set period due to a decrease in the throttle valve opening. The target intake air amount in the second combustion is equal to or longer than a period until the second combustion at the second air-fuel ratio is realized.

また、本発明による請求項３に記載の内燃機関の制御装置は、請求項１に記載の内燃機関の制御装置において、前記設定期間経過時には、アクセルペダルの踏み込み変化量に応じて過給圧が上昇するように過給圧を制御することを特徴とする。   According to a third aspect of the present invention, the internal combustion engine control apparatus according to the first aspect is the internal combustion engine control apparatus according to the first aspect, wherein, when the set period elapses, the boost pressure is increased according to a change in depression of the accelerator pedal. The supercharging pressure is controlled so as to increase.

本発明による請求項１に記載の内燃機関の制御装置によれば、第一燃焼から第二燃焼へ切り換えられる時に、設定期間の間だけはターボチャージャによる過給圧の上昇を抑制するようになっており、スロットル弁開度を減少しているにも係わらずに、過給圧の上昇によって返って吸気量が増加する可能性を低減することができる。それにより、吸気量が減少し易くなり、空燃比が第一空燃比から第一空燃比よりリッチ側の第二空燃比へ徐々に変化するように燃料噴射量が制御されても、エンジントルクは急激に高められることはなく、大きなトルクショックの発生を防止することができる。   According to the control apparatus for an internal combustion engine of the first aspect of the present invention, when the first combustion is switched to the second combustion, the increase of the supercharging pressure by the turbocharger is suppressed only during the set period. Therefore, it is possible to reduce the possibility that the intake air amount will increase due to the increase of the supercharging pressure, although the throttle valve opening is decreased. As a result, the intake air amount easily decreases, and even if the fuel injection amount is controlled so that the air-fuel ratio gradually changes from the first air-fuel ratio to the second air-fuel ratio richer than the first air-fuel ratio, the engine torque remains There is no sudden increase, and the occurrence of a large torque shock can be prevented.

また、本発明による請求項２に記載の内燃機関の制御装置によれば、請求項１に記載の内燃機関の制御装置において、設定期間は、スロットル弁開度の減少によって吸気量が切り換え時の第二燃焼における目標吸気量となって第二空燃比での第二燃焼が実現されるまでの期間以上とされ、この設定期間の間はターボチャージャによる過給圧の上昇が抑制されるために、吸気量を比較的速く目標吸気量まで減少させることができ、早期に第二空燃比での第二燃焼を実現することができる。   According to the control device for an internal combustion engine according to claim 2 of the present invention, in the control device for the internal combustion engine according to claim 1, during the set period, when the intake air amount is switched by the decrease of the throttle valve opening degree. In order to suppress the increase in supercharging pressure due to the turbocharger during this set period, the target intake air amount in the second combustion becomes the period until the second combustion at the second air-fuel ratio is realized. The intake air amount can be reduced to the target intake air amount relatively quickly, and the second combustion at the second air-fuel ratio can be realized at an early stage.

また、本発明による請求項３に記載の内燃機関の制御装置によれば、請求項１に記載の内燃機関の制御装置において、設定期間経過時には、アクセルペダルの踏み込み変化量に応じて過給圧が上昇するように過給圧を制御するようになっている。それにより、設定期間経過時に、ターボチャージャによる過給圧の上昇抑制を突然に解除すると、比較的急激に過給圧が上昇してトルクショックが発生するが、このトルクショックを抑制することができる。このトルクショックは、減少させるはずの空気量が返って増加して、増加した吸気量に対して空燃比がリッチ側の第二空燃比へ近づけられる場合に発生するトルクショックと比較すれば、それほど大きなものではないが、抑制することによりドライバビリティを向上させることができる。   According to the control apparatus for an internal combustion engine according to claim 3 of the present invention, in the control apparatus for the internal combustion engine according to claim 1, when the set period elapses, the boost pressure is determined according to the change in depression of the accelerator pedal. The supercharging pressure is controlled so as to increase. As a result, if the increase suppression of the supercharging pressure by the turbocharger is suddenly canceled when the set period has elapsed, the supercharging pressure rises relatively abruptly and a torque shock is generated, but this torque shock can be suppressed. . Compared to the torque shock that occurs when the air amount that should be decreased increases and the air-fuel ratio approaches the rich second air-fuel ratio with respect to the increased intake air amount, this torque shock is not much. Although it is not large, drivability can be improved by suppressing it.

図１は本発明による制御装置により制御される内燃機関を示す概略図である。同図において、１は機関本体であり、２は各気筒共通のサージタンクである。３はサージタンク２と各気筒とを連通する吸気枝管であり、４はサージタンク２の上流側の吸気通路である。吸気通路４におけるサージタンク２の直上流側にはスロットル弁５が配置されている。６は各気筒に連通する排気マニホルドである。   FIG. 1 is a schematic view showing an internal combustion engine controlled by a control device according to the present invention. In the figure, 1 is an engine body, and 2 is a surge tank common to each cylinder. An intake branch pipe 3 communicates the surge tank 2 with each cylinder, and 4 is an intake passage upstream of the surge tank 2. A throttle valve 5 is disposed in the intake passage 4 immediately upstream of the surge tank 2. An exhaust manifold 6 communicates with each cylinder.

機関本体１において、７は吸気弁、８は排気弁、９はピストン、１０は点火プラグである。１１は各気筒内へ直接的に燃料を噴射するための第一燃料噴射弁であり、１２は各吸気枝管３に配置された第二燃料噴射弁である。   In the engine body 1, 7 is an intake valve, 8 is an exhaust valve, 9 is a piston, and 10 is a spark plug. Reference numeral 11 denotes a first fuel injection valve for directly injecting fuel into each cylinder, and reference numeral 12 denotes a second fuel injection valve arranged in each intake branch pipe 3.

吸気通路４において、スロットル弁５の上流側にはターボチャージャ１３のコンプレッサ１３ａが配置され、コンプレッサ１３ａの上流側にはエアフローメータ１４が配置され、エアフローメータ１４の上流側はエアクリーナ（図示せず）を介して大気へ通じている。一方、排気マニホルド６の排気合流部下流側はターボチャージャ１３のタービン１３ｂに接続され、タービン１３ｂの下流側はＮＯX吸蔵還元触媒装置１５を介してマフラ（図示せず）に通じている。 In the intake passage 4, a compressor 13a of the turbocharger 13 is disposed upstream of the throttle valve 5, an air flow meter 14 is disposed upstream of the compressor 13a, and an air cleaner (not shown) is disposed upstream of the air flow meter 14. Through the atmosphere. On the other hand, the downstream side of the exhaust manifold 6 of the exhaust manifold 6 is connected to the turbine 13 b of the turbocharger 13, and the downstream side of the turbine 13 b communicates with a muffler (not shown) via the NO x storage reduction catalyst device 15.

本内燃機関は、第二燃料噴射弁１２によって吸気行程中（吸気同期）又は吸気行程開始前（吸気非同期）に燃料を噴射すると共に、第一燃料噴射弁１１によっても吸気行程で燃料を噴射し、気筒内に均質混合気を形成する均質燃焼を実施する。この均質燃焼の空燃比は、通常、理論空燃比よりリーンとされ、燃料消費を低減している。このような希薄燃焼では、多量のＮＯXが生成されないような適当なリーン空燃比（例えば、２０）が選択されるが、それでもある程度のＮＯXは生成されるために、ＮＯX吸蔵還元触媒装置１５により吸蔵してＮＯXの大気放出量を十分に低減することが必要である。 The internal combustion engine injects fuel by the second fuel injection valve 12 during the intake stroke (intake synchronization) or before the start of the intake stroke (intake asynchronous), and also by the first fuel injection valve 11 in the intake stroke. Then, homogeneous combustion is performed to form a homogeneous mixture in the cylinder. The air-fuel ratio of this homogeneous combustion is usually made leaner than the stoichiometric air-fuel ratio, reducing fuel consumption. In such lean combustion, an appropriate lean air-fuel ratio (for example, 20) is selected so that a large amount of NO X is not generated, but a certain amount of NO X is still generated, so the NO X storage reduction catalyst device. 15 it is necessary to sufficiently reduce the atmospheric emissions of occluded NO X by.

第二燃料噴射弁１２から噴射された燃料は、吸気枝管３と吸気弁７との間の吸気ポート壁面等への衝突によって微粒化され、吸気と共に気筒内へ供給されるために、気筒内で容易に気化し、良好に均質化された均質混合気を形成するのに有利である。その一方で、吸気ポート壁面等への燃料付着によって所望量の燃料を正確に気筒内へ供給することは難しい。これに対して、第一燃料噴射弁１１から噴射される燃料は、気筒内で微粒化及び気化させなければならず、多量の燃料を点火までに気化させることは難しいが、所望量の燃料を正確に気筒内へ供給することができる。   The fuel injected from the second fuel injection valve 12 is atomized by collision with the intake port wall surface between the intake branch pipe 3 and the intake valve 7 and is supplied into the cylinder together with the intake air. It is advantageous to form a gas mixture that is easily vaporized and well homogenized. On the other hand, it is difficult to accurately supply a desired amount of fuel into the cylinder due to fuel adhering to the intake port wall surface or the like. On the other hand, the fuel injected from the first fuel injection valve 11 must be atomized and vaporized in the cylinder, and it is difficult to vaporize a large amount of fuel before ignition. It can be accurately supplied into the cylinder.

それにより、必要燃料量が少なく所望量の燃料を確実に気筒内に供給することが望まれる機関低負荷時等には、主に第一燃料噴射弁１１により燃料を噴射し、必要燃料量が比較的多くなって未燃燃料の排出量が多くなり易い機関中負荷時には、主に第二燃料噴射弁１２により燃料を噴射することが好ましい。   As a result, when the engine is under a low load where it is desired that the required amount of fuel is small and the desired amount of fuel is reliably supplied into the cylinder, the fuel is mainly injected by the first fuel injection valve 11. It is preferable to inject the fuel mainly by the second fuel injection valve 12 at the time of the engine middle load that tends to increase the amount of unburned fuel that increases relatively.

さらに機関負荷が高くなって機関高負荷時になると、希薄燃焼では十分な機関出力を発生させることができず、理論空燃比での均質燃焼が実施される。この理論空燃比の均質燃焼の排気ガスを浄化するために、機関排気系に三元触媒装置を配置するようにしても良い。以下、リーン空燃比での燃焼を第一燃焼とし、理論空燃比での燃焼を第二燃焼とする。第二燃焼において、第一燃料噴射弁１１の燃料噴射割合を多くすると、気筒内での燃料気化に際して気筒内の吸気温度を低下させるために、吸気充填効率を高めることができる。   Further, when the engine load becomes higher and the engine is at a high load, the lean combustion cannot generate a sufficient engine output, and homogeneous combustion is performed at the stoichiometric air-fuel ratio. In order to purify the exhaust gas of this stoichiometric air-fuel ratio homogeneous combustion, a three-way catalyst device may be arranged in the engine exhaust system. Hereinafter, the combustion at the lean air-fuel ratio is referred to as the first combustion, and the combustion at the stoichiometric air-fuel ratio is referred to as the second combustion. In the second combustion, when the fuel injection ratio of the first fuel injection valve 11 is increased, the intake air charging efficiency can be increased in order to reduce the intake air temperature in the cylinder when fuel is vaporized in the cylinder.

こうして、機関加速時において機関負荷が設定負荷以上となると、第一燃焼から第二燃焼へ切り換えられる。それにより、燃焼空燃比は、リーン空燃比から理論空燃比へ変化することとなるが、第一燃焼から第二燃焼への切り換え時においては、僅かな負荷の上昇と、ポンピング損失が僅かに高まることとによって、必要燃料量が僅かに増加するだけであり、それにより、第一燃焼のために大きくされていたスロットル弁５開度を急激に小さくし、第二燃焼のために吸気量を大幅に減少させなければならない。   Thus, when the engine load exceeds the set load during engine acceleration, the first combustion is switched to the second combustion. As a result, the combustion air-fuel ratio changes from the lean air-fuel ratio to the stoichiometric air-fuel ratio, but at the time of switching from the first combustion to the second combustion, a slight load increase and a pumping loss slightly increase. As a result, the required amount of fuel is only slightly increased, whereby the opening of the throttle valve 5 that has been increased for the first combustion is sharply decreased, and the intake amount is increased for the second combustion. Must be reduced to

図２は、機関負荷の上昇に伴って第一燃焼から第二燃焼へ切り換えられる場合における機関トルクＴｑ、吸気量Ｇ、ターボチャージャ１３による過給圧Ｐ、及び、空燃比ＡＦのそれぞれの変化を示すタイムチャートである。   FIG. 2 shows changes in the engine torque Tq, the intake air amount G, the supercharging pressure P by the turbocharger 13, and the air-fuel ratio AF when the engine combustion is switched from the first combustion to the second combustion. It is a time chart which shows.

同図において、時刻ｔ１で要求機関負荷が設定負荷となって第一燃焼から第二燃焼へ切り換えられる。第一燃焼と第二燃焼とでは同じ機関トルクＴｑを発生させるのに必要な吸気量Ｇが大きく異なり、時刻ｔ１において、スロットル弁５は急激に閉弁される。しかしながら、吸気量Ｇは、瞬間的に、切り換え時における第一燃焼の目標吸気量Ｇ１から第二燃焼の目標吸気量Ｇ２へ変化せず、徐々にしか減少しない。   In the figure, at the time t1, the required engine load becomes the set load, and the first combustion is switched to the second combustion. The intake air amount G required to generate the same engine torque Tq differs greatly between the first combustion and the second combustion, and the throttle valve 5 is suddenly closed at time t1. However, the intake air amount G instantaneously does not change from the target intake air amount G1 of the first combustion at the time of switching to the target intake air amount G2 of the second combustion, and decreases only gradually.

本内燃機関は、ターボチャージャ１３を備えており、それによる過給によって、比較的多量の燃料が気筒内へ供給されてもリーン空燃比を実現することができ、比較的高い負荷まで第一燃焼を実施することができる。こうして、第二燃焼への切り換え直前において、第一燃焼の過給圧は、第一燃焼における最大過給圧Ｐ１となっている。この最大過給圧Ｐ１は、本実施形態において、ターボチャージャ１３のコンプレッサ１３ａ又はタービン１３ｂの過剰回転による機械的な破損を防止するためにタービン１３ｂをバイパスするウェイストゲート通路（図示せず）等を使用することによって制限されている。   The internal combustion engine is provided with a turbocharger 13 and can achieve a lean air-fuel ratio even when a relatively large amount of fuel is supplied into the cylinder by supercharging. Can be implemented. Thus, immediately before switching to the second combustion, the supercharging pressure of the first combustion is the maximum supercharging pressure P1 in the first combustion. In the present embodiment, the maximum supercharging pressure P1 is applied to a waste gate passage (not shown) that bypasses the turbine 13b in order to prevent mechanical damage due to excessive rotation of the compressor 13a or the turbine 13b of the turbocharger 13. Limited by using.

リーン空燃比の第一燃焼時の最大過給圧はＰ１であるが、コンプレッサ１３ａ及びタービン１３ｂを許容回転数としても、理論空燃比の第二燃焼では、排気ガス温度が高くなってタービン効率が高まるために、第二燃焼時の最大過給圧は、Ｐ１より高いＰ２となる。それにより、第二燃焼時では、ウェイストゲート通路等を使用することによって、過給圧が最大過給圧Ｐ２を超えないように制限される。   The maximum supercharging pressure during the first combustion with the lean air-fuel ratio is P1, but even if the compressor 13a and the turbine 13b are allowed to rotate, the exhaust gas temperature becomes higher and the turbine efficiency becomes higher in the second combustion with the stoichiometric air-fuel ratio. In order to increase, the maximum supercharging pressure during the second combustion becomes P2 higher than P1. Thereby, at the time of the second combustion, by using the waste gate passage or the like, the supercharging pressure is limited so as not to exceed the maximum supercharging pressure P2.

このような制御が第一燃焼と第二燃焼の切り換え時にそのまま実施されると、図２に点線で示すように、スロットル弁５の閉弁によって吸気量Ｇは、一旦は減少するが、吸気量の減少に伴って空燃比ＡＦがリーン空燃比ＡＦ１から理論空燃比ＡＦ２へ近づけられると、排気ガス温度が徐々に高まってタービン効率を向上させる。この時には、第一燃焼時の過給圧制限が実施されることとなり、過給圧Ｐは最大過給圧Ｐ２に達するまで徐々に高められる。   If such control is carried out as it is when switching between the first combustion and the second combustion, the intake amount G once decreases as the throttle valve 5 is closed as shown by the dotted line in FIG. When the air-fuel ratio AF is made closer to the stoichiometric air-fuel ratio AF2 as the air-fuel ratio decreases, the exhaust gas temperature gradually increases to improve the turbine efficiency. At this time, the supercharging pressure limitation during the first combustion is performed, and the supercharging pressure P is gradually increased until the maximum supercharging pressure P2 is reached.

こうして、時刻ｔ２において、吸気量は、第二燃焼の目標吸気量Ｇ２まで減少していないにも係わらずに、過給圧の上昇により増加を開始する。燃料噴射量は、機関排気系に配置された空燃比センサの出力に基づき、排気ガスの空燃比がリーン空燃比ＡＦ１から理論空燃比ＡＦ２へ徐々に変化するように制御され、すなわち、燃料噴射量は、増加する吸気量に対して空燃比を理論空燃比へ近づけるように急激に増加されてしまう。   Thus, at the time t2, the intake amount starts to increase due to the increase of the supercharging pressure, although it has not decreased to the target intake amount G2 of the second combustion. The fuel injection amount is controlled so that the air-fuel ratio of the exhaust gas gradually changes from the lean air-fuel ratio AF1 to the stoichiometric air-fuel ratio AF2 based on the output of the air-fuel ratio sensor arranged in the engine exhaust system, that is, the fuel injection amount Is rapidly increased so that the air-fuel ratio approaches the stoichiometric air-fuel ratio with respect to the increasing intake air amount.

こうして、機関トルクＴｑは、時刻ｔ２から急激に高められて、大きなトルクショックが発生してしまう。時刻ｔ４となれば、過給圧は第二燃焼の最大過給圧Ｐ２に達するために、これ以上に過給圧が上昇することはない。その後は、要求機関負荷の上昇に伴うスロットル弁の開度増加によって吸気量Ｇは徐々に増加し、それに伴って、機関トルクＴｑも徐々に増加している。   Thus, the engine torque Tq is rapidly increased from time t2, and a large torque shock is generated. At time t4, since the supercharging pressure reaches the maximum supercharging pressure P2 of the second combustion, the supercharging pressure does not increase any more. Thereafter, the intake air amount G gradually increases as the required engine load increases and the throttle valve opening increases, and the engine torque Tq gradually increases accordingly.

本実施形態は、第一燃焼から第二燃焼への切り換え時に、このように大きなトルクショックが発生することを防止するために、第一燃焼から第二燃焼へ切り換えられる時刻ｔ１から時刻ｔ３までの設定期間Ｔの間は、ウェイストゲート通路等を使用することによって第一燃焼の最大過給圧Ｐ１を維持するようになっている。それにより、図２に実線で示すように、時刻ｔ２において過給圧の上昇に伴って吸気量Ｇが増加することはなく、吸気量Ｇは時刻ｔ３において第二燃焼の目標吸気量Ｇ２まで減少する。この時刻ｔ３には、第二燃焼の理論空燃比ＡＦ２もほぼ実現される。   In the present embodiment, in order to prevent such a large torque shock from occurring when switching from the first combustion to the second combustion, from the time t1 to the time t3 when the first combustion is switched to the second combustion. During the set period T, the maximum boost pressure P1 of the first combustion is maintained by using a waste gate passage or the like. As a result, as shown by the solid line in FIG. 2, the intake air amount G does not increase with the increase of the supercharging pressure at time t2, and the intake air amount G decreases to the target intake air amount G2 for the second combustion at time t3. To do. At this time t3, the stoichiometric air-fuel ratio AF2 of the second combustion is also substantially realized.

設定期間が経過する時刻ｔ３以降においては、第一燃焼の最大過給圧Ｐ１は維持されず、それにより、過給圧は理論空燃比ＡＦ２の第二燃焼に伴う排気ガス温度の上昇によって徐々に上昇する。さらに、時刻ｔ３以降においては、要求機関負荷の上昇に伴ってスロットル弁開度も徐々に大きくされ、吸気量Ｇは比較的急激に増加する。この吸気量に対して理論空燃比ＡＦ２が維持されるように燃料噴射量も増加されるために、機関トルクＴｑはある程度急激に増加する。しかしながら、それほど大きなトルクショックは発生せず、設定期間の間も第一燃焼の最大過給圧Ｐ１を維持しない前述の場合に比較して、発生するトルクショックを十分に低減することができる。   After the time t3 when the set period elapses, the maximum boost pressure P1 of the first combustion is not maintained, and as a result, the boost pressure gradually increases as the exhaust gas temperature increases due to the second combustion of the stoichiometric air-fuel ratio AF2. To rise. Further, after time t3, the throttle valve opening is gradually increased as the required engine load increases, and the intake air amount G increases relatively abruptly. Since the fuel injection amount is also increased so that the stoichiometric air-fuel ratio AF2 is maintained with respect to this intake air amount, the engine torque Tq increases rapidly to some extent. However, such a large torque shock does not occur, and the generated torque shock can be sufficiently reduced as compared with the above-described case where the maximum boost pressure P1 of the first combustion is not maintained during the set period.

時刻ｔ５となれば、過給圧は、第二燃焼の最大過給圧Ｐ２となり、これ以上は過給圧が上昇することはなく、吸気量Ｑはスロットル弁開度の増加だけによって徐々に増加し、それに伴って機関トルクＴｑも徐々に増加することとなる。   At time t5, the boost pressure becomes the maximum boost pressure P2 of the second combustion, and the boost pressure does not increase beyond this, and the intake air amount Q gradually increases only by increasing the throttle valve opening. As a result, the engine torque Tq also gradually increases.

前述した実施形態において、設定期間Ｔの経過時（時刻ｔ３）には、第一燃焼の最大過給圧Ｐ１の維持が解除され、それにより、過給圧は比較的急激に上昇することとなるが、この過給圧Ｐの上昇が図２に一点鎖線で示すように緩やかとなるようにウェイストゲート通路を使用して規制するようにしても良い。それにより、機関トルクＴｑの変化も一点鎖線で示すように緩やかにすることができ、第一燃焼から第二燃焼への切り換えに際して殆どトルクショックを発生させないようにすることができる。   In the above-described embodiment, when the set period T has elapsed (time t3), the maintenance of the maximum boost pressure P1 of the first combustion is released, and thereby the boost pressure rises relatively rapidly. However, the waste gate passage may be used to regulate the increase of the supercharging pressure P so as to be moderate as shown by the one-dot chain line in FIG. As a result, the change in the engine torque Tq can be moderated as shown by the one-dot chain line, and almost no torque shock can be generated when switching from the first combustion to the second combustion.

しかしながら、機関急加速時のようにアクセルペダルの踏み込み変化量が大きい時には、このような過給圧の規制を実施することなく、実線で示すように機関トルクＴｑを発生させた方が要求通りとなることもある。それにより、アクセルペダルの踏み込み変化量（要求機関負荷の増加変化量）に応じた所望の過給圧の上昇が実現されるように、ウェイストゲート通路を使用して設定期間Ｔの経過後の過給圧の上昇を規制することが好ましい。この過給圧の上昇規制は、過給圧が段階的に上昇するような規制であっても良い。   However, when the amount of change in the accelerator pedal depression is large, such as when the engine suddenly accelerates, it is better to generate the engine torque Tq as indicated by the solid line without implementing such regulation of the supercharging pressure. Sometimes. As a result, the waste gate passage is used to increase the desired boost pressure according to the accelerator pedal depression change amount (the increase change amount of the requested engine load). It is preferable to restrict the increase in the supply pressure. The increase regulation of the supercharging pressure may be a regulation such that the supercharging pressure increases stepwise.

本実施形態において、設定期間Ｔの間は第一燃焼の最大過給圧Ｐ１を維持するようにしたが、これは本発明を限定するものではなく、設定期間Ｔの間において過給圧の上昇を抑制すれば良く、すなわち、設定期間Ｔの間は、過給圧を第一燃焼の最大過給圧Ｐ１より低くしても良く、また、過給圧を第一燃焼の最大過給圧Ｐ１より僅かに高くしても良い。それにより、過給圧の上昇に伴って吸気量が第二燃焼の目標吸気量に減少する以前に増加するようなことはなく、この吸気量の増加に伴って機関トルクが急激に増加して大きなトルクショックが発生することを防止することができる。   In the present embodiment, the maximum boost pressure P1 of the first combustion is maintained during the set period T, but this does not limit the present invention, and the boost pressure increases during the set period T. In other words, during the set period T, the boost pressure may be lower than the maximum boost pressure P1 of the first combustion, and the boost pressure is set to the maximum boost pressure P1 of the first combustion. It may be slightly higher. As a result, the intake air amount does not increase before the target intake air amount for the second combustion decreases as the boost pressure increases, and the engine torque increases rapidly as the intake air amount increases. It is possible to prevent a large torque shock from occurring.

設定期間Ｔは、何もしなければ排気ガス温度の上昇に伴って過給圧が上昇する時刻ｔ２より以前に経過しては意味がなく、好ましくは、第一燃焼から第二燃焼へ切り換えられる時刻ｔ１から第二燃焼の目標吸気量Ｇ２が実現されると共に理論空燃比ＡＦ２での第二燃焼が実現される時刻ｔ３以降に経過するようにすることが好ましい。   The setting period T is meaningless if it does not do anything before the time t2 when the supercharging pressure rises as the exhaust gas temperature rises, preferably the time when the first combustion is switched to the second combustion. It is preferable that the target intake air amount G2 for the second combustion is realized from t1 and that the time elapses after the time t3 when the second combustion at the stoichiometric air-fuel ratio AF2 is realized.

本実施形態では、説明を簡単にするために、第二燃焼の目標吸気量Ｇ２が実現されると同時に燃焼空燃比は理論空燃比ＡＦ２となるようにしたが、実際的には、これらは同時とならず、空燃比が理論空燃比を中心にハンチングして理論空燃比に収束する場合もある。いずれにしても、第二燃焼の目標吸気量Ｇ２に対して理論空燃比ＡＦ２での燃焼は実施される。   In the present embodiment, in order to simplify the description, the combustion air-fuel ratio is set to the stoichiometric air-fuel ratio AF2 at the same time as the target intake air amount G2 for the second combustion is realized. In some cases, the air-fuel ratio converges to the stoichiometric air-fuel ratio by hunting around the stoichiometric air-fuel ratio. In any case, combustion at the stoichiometric air-fuel ratio AF2 is performed with respect to the target intake air amount G2 of the second combustion.

本実施形態において、内燃機関は、第一燃料噴射弁１１と第二燃料噴射弁１２とを有するものとしたが、これは本発明を限定するものではなく、いずれか一方の燃料噴射弁しか有していなくても、ターボチャージャを備えて、理論空燃比よりリーンな空燃比での第一燃焼と、第一燃焼の空燃比よりリッチ側の空燃比での第二燃焼とを切り換えて実施する内燃機関であれば、本発明を適用可能である。   In the present embodiment, the internal combustion engine has the first fuel injection valve 11 and the second fuel injection valve 12, but this does not limit the present invention, and only one of the fuel injection valves is provided. Even if not, a turbocharger is provided to switch between the first combustion at an air-fuel ratio leaner than the stoichiometric air-fuel ratio and the second combustion at an air-fuel ratio richer than the air-fuel ratio of the first combustion. The present invention can be applied to any internal combustion engine.

本発明による制御装置により制御される内燃機関を示す概略図である。It is the schematic which shows the internal combustion engine controlled by the control apparatus by this invention. 第一燃焼から第二燃焼へ切り換えられる際の機関トルクＴｑ、吸気量Ｇ、過給圧Ｐ、及び、空燃比ＡＦの変化を示すタイムチャートである。6 is a time chart showing changes in engine torque Tq, intake air amount G, supercharging pressure P, and air-fuel ratio AF when switching from the first combustion to the second combustion.

符号の説明Explanation of symbols

１ 機関本体
１１ 第一燃料噴射弁
１２ 第二燃料噴射弁
１３ ターボチャージャ 1 Engine Body 11 First Fuel Injection Valve 12 Second Fuel Injection Valve 13 Turbocharger

Claims (3)

ターボチャージャを備えて、理論空燃比よりリーン側の第一空燃比での第一燃焼と、前記第一空燃比よりリッチ側の第二空燃比での第二燃焼とを切り換えて実施する内燃機関において、前記第一燃焼から前記第二燃焼へ切り換えられる時には、スロットル弁開度を減少させると共に、設定期間の間だけ前記ターボチャージャによる過給圧の上昇を抑制することを特徴とする内燃機関の制御装置。   An internal combustion engine comprising a turbocharger and switching between first combustion at a first air-fuel ratio leaner than the stoichiometric air-fuel ratio and second combustion at a second air-fuel ratio richer than the first air-fuel ratio In the internal combustion engine, when the first combustion is switched to the second combustion, the throttle valve opening is decreased and an increase in supercharging pressure by the turbocharger is suppressed only during a set period. Control device. 前記設定期間は、前記スロットル弁開度の減少によって吸気量が切り換え時の前記第二燃焼における目標吸気量となって前記第二空燃比での前記第二燃焼が実現されるまでの期間以上とすることを特徴とする請求項１に記載の内燃機関の制御装置。   The set period is equal to or longer than a period until the second combustion at the second air-fuel ratio is realized as a target intake air amount in the second combustion when the intake air amount is switched due to a decrease in the throttle valve opening. The control apparatus for an internal combustion engine according to claim 1, wherein: 前記設定期間経過時には、アクセルペダルの踏み込み変化量に応じて過給圧が上昇するように過給圧を制御することを特徴とする請求項１に記載の内燃機関の制御装置。   2. The control device for an internal combustion engine according to claim 1, wherein when the set period has elapsed, the supercharging pressure is controlled so that the supercharging pressure increases in accordance with an accelerator pedal depression change amount.
JP2005120865A 2005-04-19 2005-04-19 Control device of internal combustion engine Pending JP2006299882A (en)

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Publication number Priority date Publication date Assignee Title
JP2016121644A (en) * 2014-12-25 2016-07-07 トヨタ自動車株式会社 Control device of internal combustion engine

Citations (1)

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Publication number Priority date Publication date Assignee Title
JPH0610686A (en) * 1992-06-24 1994-01-18 Toyota Motor Corp Output control device for internal combustion engine

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0610686A (en) * 1992-06-24 1994-01-18 Toyota Motor Corp Output control device for internal combustion engine

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016121644A (en) * 2014-12-25 2016-07-07 トヨタ自動車株式会社 Control device of internal combustion engine

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