JP2003293836A - Fuel injection controller for internal combustion engine - Google Patents

Fuel injection controller for internal combustion engine

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Publication number
JP2003293836A
JP2003293836A JP2002096231A JP2002096231A JP2003293836A JP 2003293836 A JP2003293836 A JP 2003293836A JP 2002096231 A JP2002096231 A JP 2002096231A JP 2002096231 A JP2002096231 A JP 2002096231A JP 2003293836 A JP2003293836 A JP 2003293836A
Authority
JP
Japan
Prior art keywords
fuel
injection
fuel injection
injection rate
dead center
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP2002096231A
Other languages
Japanese (ja)
Other versions
JP3969156B2 (en
Inventor
Takashi Shinjo
崇 新城
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nissan Motor Co Ltd
Original Assignee
Nissan Motor Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nissan Motor Co Ltd filed Critical Nissan Motor Co Ltd
Priority to JP2002096231A priority Critical patent/JP3969156B2/en
Publication of JP2003293836A publication Critical patent/JP2003293836A/en
Application granted granted Critical
Publication of JP3969156B2 publication Critical patent/JP3969156B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Landscapes

  • Fuel-Injection Apparatus (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To suppress smoke by properly setting an injection rate of fuel in a diesel engine or the like. <P>SOLUTION: Since a strong air flow occurs against a fuel injection direction when injecting fuel in an area II in a top dead center neighborhood before a compression top dead center in the diesel engine, by largely controlling the injection rate to increase penetration force of the fuel going against the air flow than in fuel injection in an area I of a precedent compression stroke and an area III after the compression top dead center, a spray range is increased and sufficient mixture distribution is secured. By this, occurrence of an excessively fuel-rich area is suppressed and smoke is prevented. <P>COPYRIGHT: (C)2004,JPO

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】本発明は、内燃機関の燃料噴
射制御装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine.

【０００２】[0002]

【従来の技術】従来の直接噴射式ディーゼルエンジンに
おいて、特開平１０−２８８０３８ではスワールを強め
た条件では燃料噴射率を低下させ、混合気分布領域を制
御することで空気利用率の向上を図っている。2. Description of the Related Art In a conventional direct injection diesel engine, in JP-A-10-288038, the fuel injection rate is lowered under the condition that the swirl is strengthened, and the air utilization rate is improved by controlling the air-fuel mixture distribution region. There is.

【０００３】[0003]

【発明が解決しようとする課題】ところで、筒内の空気
流動は、スワール強度によって異なることのほかにピス
トン位置によっても異なる。図４、５に示すように、圧
縮行程（領域Ｉ、II）では筒内の空気はピストンの燃焼
室内に流れ込み、逆に、膨張行程（領域III）ではピス
トンの燃焼室内からピストン冠面へ流れ出していく。By the way, the air flow in the cylinder varies not only with the swirl strength but also with the piston position. As shown in FIGS. 4 and 5, in the compression stroke (regions I and II), the air in the cylinder flows into the combustion chamber of the piston, and conversely, in the expansion stroke (region III), it flows out from the combustion chamber of the piston to the crown surface of the piston. To go.

【０００４】したがって、燃料噴射を開始してから終了
するまでの期間（噴射期間）が、筒内の空気がピストン
の燃焼室内に流れ込む領域Ｉ、IIにあるか、それとも、
ピストンの燃焼室内からピストン冠面へ流れ出していく
領域IIIにあるかによって、筒内に噴射された燃料の分
布（混合気分布）は異なる。例えば、領域IIとIIIとで
比較すると、領域IIIで噴射された燃料がピストン壁面
に到達しないように噴射率を設定すると、領域Ｉではピ
ストンの燃焼室内に流れ込む空気の流速に対して噴射率
が小さく、噴射された燃料が噴射弁付近に留まって局所
的に燃料過濃領域が形成されるため、空気利用率が低下
してしまう。Therefore, the period from the start of fuel injection to the end thereof (injection period) is in the regions I and II where the air in the cylinder flows into the combustion chamber of the piston, or
The distribution of the fuel injected into the cylinder (mixture mixture distribution) differs depending on whether it is in the region III flowing out from the combustion chamber of the piston to the crown surface of the piston. For example, comparing Regions II and III, if the injection rate is set so that the fuel injected in Region III does not reach the piston wall surface, in Region I, the injection rate is relative to the flow velocity of the air flowing into the combustion chamber of the piston. Since the injected fuel remains small and the fuel rich region is locally formed near the injection valve, the air utilization ratio is reduced.

【０００５】しかしながら、上記従来技術では、燃料の
噴射率を制御する際に、スワール強度のみを考慮したも
ので、燃料の噴射期間を考慮したものではないため、場
合によっては燃料過濃領域が形成されて空気利用率の低
下によってスモークが発生するといった恐れがあった。
本発明は、このような従来の課題に着目してなされたも
ので、燃料の噴射期間を考慮して燃料噴射率を制御する
ことにより、空気利用率を十分に高めることができる内
燃機関の燃料噴射制御装置を提供することを目的とす
る。However, in the above-mentioned prior art, when controlling the fuel injection rate, only the swirl intensity is taken into consideration, not the fuel injection period. Therefore, a fuel rich region is formed in some cases. There is a risk that smoke will be generated due to a decrease in the air utilization rate.
The present invention has been made in view of such a conventional problem, and by controlling the fuel injection rate in consideration of the fuel injection period, the fuel of the internal combustion engine capable of sufficiently increasing the air utilization rate. An object is to provide an injection control device.

【０００６】[0006]

【課題を解決するための手段】このため、請求項１に係
る発明は、筒内に燃料を直接噴射可能であり、かつ、噴
射率を制御可能な燃料噴射手段と、燃料噴射を開始して
から終了するまでの期間の圧縮上死点に対する位置に基
づき前記噴射率を制御する噴射率制御手段と、を備えた
ことを特徴とする。Therefore, in the invention according to claim 1, the fuel can be directly injected into the cylinder, and the fuel injection means can control the injection rate, and the fuel injection can be started. Injection rate control means for controlling the injection rate based on the position with respect to the compression top dead center during the period from the end to the end.

【０００７】請求項１に係る発明によると、圧縮上死点
に対する位置によって、筒内の空気流動特性が変化し、
燃焼室壁面への付着や燃料過濃領域の形成を抑制しつ
つ、できるだけ空気利用率を高めることができる噴射率
が、前記空気流動特性によって異なる。そこで、燃料噴
射期間の圧縮上死点に対する位置によって、そのときの
空気流動特性に見合った最適な噴射率に制御することが
できる。According to the invention of claim 1, the air flow characteristic in the cylinder changes depending on the position with respect to the compression top dead center,
The injection rate capable of increasing the air utilization rate as much as possible while suppressing the adhesion to the wall surface of the combustion chamber and the formation of the fuel rich region differs depending on the air flow characteristics. Therefore, depending on the position of the fuel injection period with respect to the compression top dead center, it is possible to control the injection rate to an optimum value that matches the air flow characteristics at that time.

【０００８】また、請求項２に係る発明は、前記噴射率
制御手段は、燃料噴射を開始してから終了するまでの期
間が圧縮上死点前に位置するときの噴射率を、圧縮上死
点後に位置するときの噴射率以上とすることを特徴とす
る。請求項２に係る発明によると、圧縮上死点前、特
に、上死点近傍では筒内に燃料噴射方向に対向して強い
空気流動が発生するので、筒内の空気流動方向が反転す
る圧縮上死点後に比較して噴射率を大きくして空気流動
に対向する燃料の貫徹力を増大することにより、噴霧到
達距離を増大して十分な混合気分布を確保する。これに
より、燃料過濃領域の発生を抑制でき、スモーク発生を
防止できる。In the invention according to claim 2, the injection rate control means sets the injection rate when the period from the start to the end of the fuel injection is located before the compression top dead center. It is characterized in that the injection rate is equal to or higher than the injection rate when positioned after the point. According to the second aspect of the present invention, before the compression top dead center, in particular, near the top dead center, a strong air flow is generated in the cylinder so as to face the fuel injection direction. By increasing the injection rate and increasing the penetrating force of the fuel opposed to the air flow as compared with after the top dead center, the spray reaching distance is increased and a sufficient air-fuel mixture distribution is secured. As a result, it is possible to suppress the generation of the fuel rich region and prevent the generation of smoke.

【０００９】一方、圧縮上死点後は、噴射率を大きくす
ると短時間で噴射しつくされた燃料が局部的に存在して
燃料過濃領域を形成しやすくなるので、噴射率を小さく
して時間かけて噴射することにより空気利用率を高める
ことができる。また、請求項３に係る発明は、前記噴射
率制御手段は、燃料噴射を開始してから終了するまでの
期間が圧縮上死点を含むとき、燃料噴射を開始してから
終了するまでの間で、圧縮上死点後より圧縮上死点前の
噴射率を大きくすることを特徴とする。On the other hand, after the compression top dead center, if the injection rate is increased, the injected fuel is locally present in a short time and it is easy to form a fuel rich region. Air injection can be increased by injecting over time. Further, in the invention according to claim 3, when the period from the start to the end of the fuel injection includes the compression top dead center, the injection rate control means from the start to the end of the fuel injection. Thus, the injection rate before the compression top dead center is made larger than after the compression top dead center.

【００１０】請求項３に係る発明によると、請求項２で
説明した理由により、噴射期間が圧縮上死点を含むと
き、圧縮上死点後より圧縮上死点前の噴射率を大きくす
ることにより、圧縮上死点前後で変化する空気流動に見
合った最適な噴射率に制御することができる。また、請
求項４に係る発明は、前記噴射率制御手段は、燃料噴射
を開始してから終了するまでの期間が圧縮上死点前に位
置するとき、燃料噴射を開始してから終了するまでの
間、圧縮上死点に近づくほど噴射率を大きくすることを
特徴とする。According to the invention of claim 3, for the reason explained in claim 2, when the injection period includes the compression top dead center, the injection rate before the compression top dead center is made larger than after the compression top dead center. As a result, it is possible to control the injection rate to an optimum value corresponding to the air flow that changes before and after the compression top dead center. In the invention according to claim 4, the injection rate control means, when the period from the start to the end of the fuel injection is located before the compression top dead center, until the end to the end of the fuel injection. During this period, the injection rate is increased as it approaches the compression top dead center.

【００１１】請求項４に係る発明によると、圧縮行程で
も圧縮上死点から離れているときは、燃料噴射方向に対
向する空気流動が比較的弱く、圧縮上死点に近づくにつ
れて急激に強くなるので、圧縮上死点に近づくほど噴射
率を大きくして燃料貫徹力を大きくすることで良好な混
合気分布を確保することができる。According to the fourth aspect of the present invention, even in the compression stroke, when the air is away from the compression top dead center, the air flow opposed to the fuel injection direction is relatively weak, and becomes sharply stronger as the compression top dead center is approached. Therefore, a better mixture distribution can be ensured by increasing the injection rate and increasing the fuel penetration force as it approaches the compression top dead center.

【００１２】また、請求項５に係る発明は、前記噴射率
制御手段は、スワール比が低いときほど、前記噴射率を
大きくする度合いを大きくすることを特徴とする。請求
項５に係る発明によると、燃料に対する空気流動の影響
はスワールに応じて変化し、スワール比が低い（スワー
ルが弱い）ときほど空気利用率が低下する。そこで、ス
ワール比が低いときほど、前記噴射率を大きくする度合
いを大きくすることにより、より正確に燃料の空気利用
率の低下を防止できる。The invention according to claim 5 is characterized in that the injection rate control means increases the degree of increasing the injection rate as the swirl ratio is lower. According to the invention of claim 5, the influence of the air flow on the fuel changes according to the swirl, and the air utilization rate decreases as the swirl ratio is lower (the swirl is weaker). Therefore, the lower the swirl ratio, the greater the degree of increasing the injection rate, so that it is possible to more accurately prevent the decrease in the air utilization rate of fuel.

【００１３】また、請求項６に係る発明は、前記噴射率
制御手段は、エンジン回転数が大きいときほど、前記噴
射率を大きくする度合いを大きくすることを特徴とす
る。燃料に対する空気流動の影響はエンジン回転数に応
じて変化し、エンジン回転数が高いときほど空気利用率
が低下する。そこで、エンジン回転数が高いほど、前記
噴射率を大きくする度合いを大きくすることにより、よ
り正確に燃料の空気利用率の低下を防止できる。Further, the invention according to claim 6 is characterized in that the injection rate control means increases the degree of increasing the injection rate as the engine speed increases. The effect of air flow on the fuel changes according to the engine speed, and the higher the engine speed, the lower the air utilization rate. Therefore, by increasing the degree of increasing the injection rate as the engine speed increases, it is possible to more accurately prevent the decrease in the air utilization rate of fuel.

【００１４】また、請求項７に係る発明は、前記燃料噴
射手段は、針弁のリフト量を制御することで前記噴射期
間中の噴射率を制御することを特徴とする。請求項７に
係る発明によると、圧電素子を内蔵するなど針弁のリフ
ト量を制御できるものでは、該リフト量を制御すること
によって噴射期間中の噴射率を直接可変制御することが
できる。The invention according to claim 7 is characterized in that the fuel injection means controls the injection rate during the injection period by controlling the lift amount of the needle valve. According to the seventh aspect of the present invention, in a device that can control the lift amount of the needle valve, such as by incorporating a piezoelectric element, the injection rate during the injection period can be directly variably controlled by controlling the lift amount.

【００１５】また、請求項８に係る発明は、前記燃料噴
射手段は、燃料を複数回に分割して噴射することで前記
噴射期間中の噴射率を制御することを特徴とする。請求
項８に係る発明によると、針弁のリフト量を制御できな
いものでも、針弁の開閉タイミングを制御して燃料を複
数回に分割して噴射することにより、噴射期間中の噴射
率を擬似的に可変制御することができる。Further, the invention according to claim 8 is characterized in that the fuel injection means controls the injection rate during the injection period by injecting the fuel in a plurality of divided injections. According to the invention of claim 8, even if the lift amount of the needle valve cannot be controlled, the injection rate during the injection period is simulated by controlling the opening / closing timing of the needle valve and injecting the fuel in multiple times. Can be variably controlled.

【００１６】[0016]

【発明の実施の形態】図１は、本発明に係るディーゼル
エンジン全体の構成を示した概略図である。このディー
ゼルエンジン１は、いわゆるコモンレール式燃料噴射装
置を備え、高圧燃料ポンプ２によって所定圧力に加圧さ
れた燃料は、コモンレール３に導入され、該コモンレー
ル３を介して、各気筒の燃料噴射ノズル４に供給され
る。上記燃料噴射ノズル４は、コントロールユニット１
１からの制御信号によって開閉制御され、燃料噴射量、
噴射時期、ならびに噴射回数を気筒毎に独立して制御す
ることが可能である。1 is a schematic diagram showing the overall construction of a diesel engine according to the present invention. The diesel engine 1 includes a so-called common rail fuel injection device, and fuel pressurized to a predetermined pressure by the high-pressure fuel pump 2 is introduced into the common rail 3 and the fuel injection nozzle 4 of each cylinder is introduced through the common rail 3. Is supplied to. The fuel injection nozzle 4 is the control unit 1
The opening and closing control is performed by the control signal from 1, the fuel injection amount,
The injection timing and the number of injections can be controlled independently for each cylinder.

【００１７】また、このディーゼルエンジン１は、可変
ノズル型のターボ過給機５を備え、排気通路６にタービ
ンが、吸気通路７にコンプレッサが、それぞれ配置され
るとともに、上記吸気通路７のコンプレッサ下流に、イ
ンタークーラー８を備える。上記ターボ過給機５の可変
ノズルのノズル開度は、図示しないセンサによって検出
され、ノズル開度信号としてコントロールユニット１１
に入力される。Further, the diesel engine 1 is provided with a variable nozzle type turbocharger 5, a turbine is arranged in an exhaust passage 6 and a compressor is arranged in an intake passage 7, and a compressor downstream of the intake passage 7 is provided. In addition, the intercooler 8 is provided. The nozzle opening of the variable nozzle of the turbocharger 5 is detected by a sensor (not shown), and is output as a nozzle opening signal to the control unit 11.
Entered in.

【００１８】さらに、このディーゼルエンジン１は、排
気還流装置を備える。すなわち、排気通路６と吸気通路
７との間にＥＧＲ通路１２を備え、該ＥＧＲ通路１２に
ＥＧＲバルブ１３が介装されている。このＥＧＲバルブ
１３の開度は、コントロールユニット１１が出力するＥ
ＧＲバルブ制御信号によって制御される。また、上記デ
ィーゼルエンジン１は、クランク角を検出するクランク
角センサ１４と、運転者により操作されるアクセル開度
を検出するアクセル開度センサ１５とを備え、これらの
検出信号もコントロールユニット１１に入力されてい
る。なお。前記クランク角センサ１４により、検出され
るクランク角によりエンジン回転数Ｎｅを検出可能であ
ると共に、前記噴射時期を制御可能である。Further, the diesel engine 1 has an exhaust gas recirculation device. That is, the EGR passage 12 is provided between the exhaust passage 6 and the intake passage 7, and the EGR valve 13 is interposed in the EGR passage 12. The opening degree of the EGR valve 13 is E output from the control unit 11.
It is controlled by the GR valve control signal. The diesel engine 1 also includes a crank angle sensor 14 that detects a crank angle and an accelerator opening sensor 15 that detects an accelerator opening operated by a driver, and these detection signals are also input to the control unit 11. Has been done. Incidentally. The crank angle sensor 14 can detect the engine speed Ne based on the detected crank angle and can control the injection timing.

【００１９】前記燃料噴射ノズル４としては、例えば、
噴孔を開閉する針弁に燃料背圧を加える背圧室と、燃料
タンクに通じる燃料戻し通路とを、別に内蔵された電磁
弁によって開閉することにより、前記燃料背圧を高圧と
低圧とに切り換えて針弁を開閉駆動するものがある。こ
のものでは、電磁弁への通電間隔、時期を制御すること
により、燃料噴射量、噴射時期を自由に制御でき、１サ
イクルの通電回数を複数に制御することができる。これ
によって、噴射率を擬似的に可変制御することができ
る。As the fuel injection nozzle 4, for example,
The back pressure chamber that applies fuel back pressure to the needle valve that opens and closes the injection hole, and the fuel return passage that communicates with the fuel tank are opened and closed by separately built-in solenoid valves, thereby increasing the fuel back pressure into high pressure and low pressure. There is one that switches to open and close the needle valve. In this device, the fuel injection amount and the injection timing can be freely controlled by controlling the energization interval and timing of the solenoid valve, and the number of energizations in one cycle can be controlled to be plural. Thereby, the injection rate can be pseudo-variably controlled.

【００２０】また、燃料噴射ノズル４の別のタイプとし
て、針弁に連係する圧電素子を備えたものがあり、該圧
電素子への印加電圧を大きくすると圧電素子の伸び量が
増大して針弁が閉弁し、燃料噴射が停止する。このもの
では、圧電素子への印加電圧、時期を制御することによ
り、燃料噴射量、噴射時期自由に制御でき、１サイクル
の通電回数を複数にすることができる。また、印加電圧
の制御により、噴射率を制御することができる。As another type of the fuel injection nozzle 4, there is one provided with a piezoelectric element linked to the needle valve. When the voltage applied to the piezoelectric element is increased, the expansion amount of the piezoelectric element increases and the needle valve Closes and fuel injection stops. In this device, the fuel injection amount and the injection timing can be freely controlled by controlling the voltage applied to the piezoelectric element and the timing, and the number of times of energization in one cycle can be made plural. Further, the injection rate can be controlled by controlling the applied voltage.

【００２１】次に、本発明にかかわる噴射率制御につい
て説明する。図２に、本発明に対応した噴射時期の３つ
の領域について示す。領域Ｉは、圧縮行程期間である。
領域IIは、圧縮行程中の上死点前近傍、例えば上死点前
１０度から上死点までの期間である。領域IIIは、圧縮
上死点以降の膨張行程期間である。図３に、図２に対応
したクランク時期における筒内空気流動を示す。領域Ｉ
およびIIでは、筒内の空気はピストン冠面上に設置され
た燃焼室内に流れこみ、その流速は領域Ｉに比べ領域II
の場合に大きくなる。領域IIIでは、圧縮行程中に流れ
込んだ空気、および燃料混合気が、燃焼室内からピスト
ン冠面上部へ流れ出していく。Next, the injection rate control according to the present invention will be described. FIG. 2 shows three regions of the injection timing corresponding to the present invention. Region I is the compression stroke period.
Region II is a region near top dead center during the compression stroke, for example, a period from 10 degrees before top dead center to top dead center. Region III is the expansion stroke period after the compression top dead center. FIG. 3 shows the in-cylinder air flow at the crank timing corresponding to FIG. Region I
And II, the air in the cylinder flows into the combustion chamber installed on the crown surface of the piston, and its flow velocity is higher than that in the region I.
It becomes large when. In the region III, the air and the fuel mixture flowing during the compression stroke flow out from the combustion chamber to the upper portion of the piston crown surface.

【００２２】図４は、本発明の噴射率制御を示す。前述
したように、噴射時期を領域Ｉ〜IIIに分割する。燃焼
室への空気流動が弱い領域Ｉ（図４−ａ）、および空気
流動が燃焼室から流出する領域III（図４−ｅ）で燃料
噴射を行う場合は、噴射率を小さく設定する。一方、燃
料噴射方向に対向する空気流動が強くなる領域II（図４
−ｃ）では、噴射率を大きく設定する。FIG. 4 shows the injection rate control of the present invention. As described above, the injection timing is divided into regions I to III. When the fuel injection is performed in the region I (FIG. 4-a) where the air flow to the combustion chamber is weak and the region III (FIG. 4-e) where the air flow flows out of the combustion chamber, the injection rate is set small. On the other hand, a region II (Fig.
In -c), the injection rate is set large.

【００２３】また、燃料噴射期間が長く、領域Ｉ−II、
あるいは領域II−IIIの双方を含む場合（図４−ｂ、
ｄ）は、領域IIの期間中の燃料噴射率を大きく設定す
る。さらに、燃料噴射期間が長く、領域Ｉ−II−IIIに
跨る場合（図４−ｆ）は、領域IIの期間中の燃料噴射率
を大きく設定し、領域Ｉ、領域IIIの期間中の燃料噴射
率を小さく設定する。Further, the fuel injection period is long, and the regions I-II,
Alternatively, when both regions II-III are included (Fig. 4-b,
In d), the fuel injection rate during the period of region II is set to a large value. Further, when the fuel injection period is long and extends over the region I-II-III (Fig. 4-f), the fuel injection rate during the period of the region II is set to be large, and the fuel injection during the period of the region I and the region III is performed. Set a small rate.

【００２４】本発明では、燃焼室に流入する空気流動に
よらず、所望の領域に混合気を形成することを目的とし
ており、その効果が大きい低スワール時について図を用
いて詳細に説明する。図５に示すように、領域Ｉで噴射
された燃料は、燃焼室壁面近傍かつ壁面に付着しない領
域まで到達し所望の領域に燃料混合気分布を形成する。
本発明を用いず、領域IIでも領域Ｉと同一の小さい噴射
率に制御した場合、図６（Ａ）に示すように、領域IIで
噴射された燃料は、燃焼室に流れ込む空気流動速度が増
大し、かつ低スワール時には旋回方向の流速が小さいの
で、燃焼室中心部へ流入する空気流の流速と噴霧の噴射
方向とが対向する形態となるため噴霧到達距離が短くな
る。これにより噴霧先端部に燃料混合気が留まるため、
局所的に燃料過濃領域（図中ハッチング部）が形成さ
れ、スモーク発生などにつながる。The purpose of the present invention is to form the air-fuel mixture in a desired region irrespective of the air flow flowing into the combustion chamber, and a detailed description will be given with reference to the drawings when the low swirl is effective. As shown in FIG. 5, the fuel injected in the region I reaches a region near the wall surface of the combustion chamber and does not adhere to the wall surface to form a fuel mixture distribution in a desired region.
When the injection rate is controlled to be the same as in the region I in the region II without using the present invention, as shown in FIG. 6A, the fuel injected in the region II has an increased air flow velocity flowing into the combustion chamber. In addition, since the flow velocity in the swirling direction is low at low swirl, the flow velocity of the air flow flowing into the center of the combustion chamber and the spraying direction of the spray are opposed to each other, so that the spray reaching distance becomes short. This keeps the fuel mixture at the spray tip,
A fuel rich region (hatched portion in the figure) is locally formed, which leads to smoke generation.

【００２５】図６（Ｂ）は、領域IIに本発明を適用した
ときの改善効果を示す。燃焼室内に流れ込む空気流動は
強くなっているが、燃料噴射率を高めた効果により燃料
噴霧の貫徹力が増し、燃料過濃領域の形成が抑制され、
領域Ｉと同様の広い領域にわたって燃料混合気の形成が
可能となる。図７は、スワール比やエンジン回転数によ
って噴射率を可変制御する実施形態を示す。FIG. 6B shows the improvement effect when the present invention is applied to the area II. Although the air flow flowing into the combustion chamber is strong, the penetration force of the fuel spray is increased by the effect of increasing the fuel injection rate, and the formation of the fuel rich region is suppressed,
It is possible to form the fuel mixture over a wide area similar to the area I. FIG. 7 shows an embodiment in which the injection rate is variably controlled according to the swirl ratio and the engine speed.

【００２６】すなわち、スワール比（強度）が小さいと
きほど、または、エンジン回転数が大きいときほど、領
域IIで噴射率（の平均値）を大きくする度合いを大きく
する。 図３に示した領域IIでの燃料に対する空気の流
れの影響はスワールに応じて変化し、スワールが強いと
きより弱いときの方が空気利用率が低下する。よって、
スワールが小さいときは大きいときより噴射率を大きく
することにより、より正確に燃料の空気利用率の低下を
防止できる。That is, the smaller the swirl ratio (strength) is or the larger the engine speed is, the greater the degree of increasing (the average value of) the injection rate in the region II is. The influence of the air flow on the fuel in the region II shown in FIG. 3 varies depending on the swirl, and the air utilization rate is lower when the swirl is weaker than when it is strong. Therefore,
When the swirl is small, the injection rate can be made larger than that when the swirl is large, so that the decrease in the air utilization rate of the fuel can be prevented more accurately.

【００２７】同様に、領域IIでの燃料に対する空気の流
れの影響はエンジン回転数に応じて変化し、エンジン回
転数が小さいときより大きいときの方が、空気利用率が
低下する。よって、エンジン回転数が高いときは低いと
きより噴射率を大きくすることにより、より正確に燃料
の空気利用率の低下を防止できる。Similarly, the influence of the air flow on the fuel in the region II changes depending on the engine speed, and when the engine speed is low, it is higher than that when the engine speed is low. Therefore, when the engine speed is high, the injection rate is made larger than that when the engine speed is low, so that the decrease in the air utilization rate of the fuel can be prevented more accurately.

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明の実施形態の全体構成を示す図。FIG. 1 is a diagram showing an overall configuration of an embodiment of the present invention.

【図２】本発明の実施形態に対応した噴射時期の３つの
領域を示す図。FIG. 2 is a diagram showing three regions of injection timing corresponding to the embodiment of the present invention.

【図３】上記３つの領域における筒内の空気流動状態を
示す縦断面図。FIG. 3 is a vertical cross-sectional view showing an air flow state in a cylinder in the above three regions.

【図４】同上実施形態における噴射時期による噴射率の
各種制御を示す図。FIG. 4 is a diagram showing various controls of an injection rate according to an injection timing in the same embodiment.

【図５】同上実施形態のスワールが弱いときの特定の領
域Ｉにおける燃料噴霧分布状態を示す横断面図。FIG. 5 is a transverse sectional view showing a fuel spray distribution state in a specific region I when the swirl of the embodiment is weak.

【図６】同上実施形態のスワールが弱いときの特定の領
域IIにおける燃料噴霧分布状態（Ｂ）を、本発明を適用
しない場合（Ａ）と比較して示す横断面図。FIG. 6 is a transverse cross-sectional view showing a fuel spray distribution state (B) in a specific region II when the swirl of the embodiment is weak compared with a case (A) where the present invention is not applied.

【図７】スワール強度またはエンジン回転数に応じて噴
射時期領域毎の噴射率を変える実施形態を示す図。FIG. 7 is a diagram showing an embodiment in which an injection rate is changed for each injection timing region according to swirl intensity or engine speed.

【符号の説明】[Explanation of symbols]

１ ディーゼルエンジン ３ コモンレール ４ 燃料噴射ノズル １１ コントロールユニット １４ クランク角センサ １５ アクセル開度センサ 1 diesel engine 3 common rail 4 Fuel injection nozzle 11 Control unit 14 Crank angle sensor 15 Accelerator position sensor

───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｆ０２Ｍ 51/06 Ｆ０２Ｍ 51/06 Ｍ Ｆターム(参考） 3G066 AA07 AA11 AA13 AB02 AC09 AD12 BA13 BA24 CC06T CC08T CC08U CC14 CC67 CC68U CD26 CE13 CE22 CE27 DA08 DC00 DC04 DC05 DC09 DC14 3G301 HA02 HA04 HA13 HA17 JA02 JA24 JA26 LA05 LB00 LB06 LB11 LB17 LC00 LC01 MA18 MA23 MA26 MA27 NA07 ND42 NE01 PA11Z PA16Z PD15Z PE01Z PE03Z PE08Z PF03Z─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. 7 Identification code FI theme code (reference) F02M 51/06 F02M 51/06 MF term (reference) 3G066 AA07 AA11 AA13 AB02 AC09 AD12 BA13 BA24 CC06T CC08T CC08U CC14 CC67 CC68U CD26 CE13 CE22 CE27 DA08 DC00 DC04 DC05 DC09 DC14 3G301 HA02 HA04 HA13 HA17 JA02 JA24 JA26 LA05 LB00 LB06 LB11 LB17 LC00 LC01 MA18 MA23 MA26 MA27 NA07 ND42 NE01 PA11Z PA16Z PD15Z PE01Z PE03Z PE08Z PF03Z

Claims (8)

【特許請求の範囲】[Claims] 【請求項１】筒内に燃料を直接噴射可能であり、かつ、
噴射率を制御可能な燃料噴射手段と、 燃料噴射を開始してから終了するまでの期間の圧縮上死
点に対する位置に基づき前記噴射率を制御する噴射率制
御手段と、 を備えたことを特徴とする内燃機関の燃料噴射制御装
置。1. A fuel can be directly injected into a cylinder, and
Fuel injection means capable of controlling the injection rate; and injection rate control means for controlling the injection rate based on the position with respect to the compression top dead center during the period from the start to the end of the fuel injection. And a fuel injection control device for an internal combustion engine. 【請求項２】前記噴射率制御手段は、燃料噴射を開始し
てから終了するまでの期間が圧縮上死点前に位置すると
きの噴射率を、圧縮上死点後に位置するときの噴射率以
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
燃料噴射制御装置。2. The injection rate control means sets the injection rate when the period from the start to the end of fuel injection is located before compression top dead center to the injection rate when it is located after compression top dead center. The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel injection control device is as described above. 【請求項３】前記噴射率制御手段は、燃料噴射を開始し
てから終了するまでの期間が圧縮上死点を含むとき、燃
料噴射を開始してから終了するまでの間で、圧縮上死点
後より圧縮上死点前の噴射率を大きくすることを特徴と
する請求項２に記載の内燃機関の燃料制御装置。3. The injection rate control means, when the period from the start of fuel injection to the end thereof includes compression top dead center, compression top dead center between the start and end of fuel injection. The fuel control device for an internal combustion engine according to claim 2, wherein the injection rate before compression top dead center is made higher than that after compression. 【請求項４】前記噴射率制御手段は、燃料噴射を開始し
てから終了するまでの期間が圧縮上死点前に位置すると
き、燃料噴射を開始してから終了するまでの間、圧縮上
死点に近づくほど噴射率を大きくすることを特徴とする
請求項２または請求項３に記載の内燃機関の燃料制御装
置。4. The injection rate control means, when the period from the start of fuel injection to the end thereof is located before compression top dead center, the compression rate is increased from the start of fuel injection to the end thereof. The fuel control device for an internal combustion engine according to claim 2 or 3, wherein the injection rate is increased as it approaches the dead center. 【請求項５】前記噴射率制御手段は、スワール比が低い
ときほど、前記噴射率を大きくする度合いを大きくする
ことを特徴とする請求項１〜請求項４のいずれか１つに
記載の内燃機関の燃料噴射制御装置。5. The internal combustion engine according to claim 1, wherein the injection rate control unit increases the degree of increasing the injection rate as the swirl ratio is lower. Engine fuel injection control device. 【請求項６】前記噴射率制御手段は、エンジン回転数が
大きいときほど、前記噴射率を大きくする度合いを大き
くすることを特徴とする請求項１〜請求項４のいずれか
１つに記載の内燃機関の燃料噴射制御装置。6. The injection rate control means increases the degree of increasing the injection rate as the engine speed is higher, as claimed in any one of claims 1 to 4. Fuel injection control device for internal combustion engine. 【請求項７】前記燃料噴射手段は、針弁のリフト量を制
御することで前記噴射期間中の噴射率を制御することを
特徴とする請求項１〜請求項６のいずれか１つに記載の
内燃機関の燃料噴射制御装置。7. The fuel injection means controls the injection rate during the injection period by controlling the lift amount of a needle valve, according to any one of claims 1 to 6. Fuel injection control device for internal combustion engine. 【請求項８】前記燃料噴射手段は、燃料を複数回に分割
して噴射することで前記噴射期間中の噴射率を制御する
ことを特徴とする請求項１〜請求項６のいずれか１つに
記載の内燃機関の燃料噴射制御装置。8. The fuel injection means controls the injection rate during the injection period by injecting fuel in a plurality of divided injections. A fuel injection control device for an internal combustion engine according to item 1.
JP2002096231A 2002-03-29 2002-03-29 Fuel injection control device for internal combustion engine Expired - Fee Related JP3969156B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2002096231A JP3969156B2 (en) 2002-03-29 2002-03-29 Fuel injection control device for internal combustion engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2002096231A JP3969156B2 (en) 2002-03-29 2002-03-29 Fuel injection control device for internal combustion engine

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Publication Number Publication Date
JP2003293836A true JP2003293836A (en) 2003-10-15
JP3969156B2 JP3969156B2 (en) 2007-09-05

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Country Link
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9371796B2 (en) 2011-01-07 2016-06-21 Nissan Motor Co., Ltd. Combustion control device and method for diesel engine

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9371796B2 (en) 2011-01-07 2016-06-21 Nissan Motor Co., Ltd. Combustion control device and method for diesel engine

Also Published As

Publication number Publication date
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