JP4069335B2 - Engine fuel injection control device - Google Patents

Description

次のステップＳ１８では、上式(2)から演算されたギヤ比Ｇrが上記表１に示すギヤ比Ｇrの範囲内にあり、値Ｇr1（ここでは、１６．５）未満であるか否か、即ち演算されたギヤ比Ｇrが値Ｇr1以上となっていないかどうかを判別する。
【００３２】
ステップＳ１８の判別結果が偽（Ｎｏ）で、演算されたギヤ比Ｇrが値Ｇr1（上記１６．５）以上である場合には、上式(2)より、エンジン回転速度Ｎeが過剰に大きくなっており、即ちエンジンが空ぶかし状態にあると判断でき、このような場合には、変速段がニュートラル段に有ると判定する。そして、変速段がこのようにニュートラル段に有る場合には、問題となるようなショックが発生することはないので、そのまま当該ルーチンを抜ける。
【００３３】
一方、ステップＳ１８の判別結果が真（Ｙｅｓ）で、演算されたギヤ比Ｇrが値Ｇr1未満であって、上記表１に示す範囲内である場合には、次にステップＳ２０に進む。
【００３４】
ステップＳ２０では、許容エンジントルクΔＴea演算部４２において、上記表１に基づき決定された変速段に対応する固有のギヤ比Ｇr（１速段であれば例えばＧr=13.3等）に基づいて次式(3)より許容エンジントルクΔＴeaを演算する。
【００３５】
ΔＴea＝ΔＴvh／Ｇr …(3)
ここに、ΔＴvhは、加減速時にショックが生じないよう実験等により予め設定された許容駆動トルク（所定の許容駆動トルク）である。
【００３６】
通常、加減速時に発生するショックは駆動トルクが急激に大きく変化することにより生ずるものであるため、本発明では、このようにして、先ず駆動トルクを所定の許容駆動トルクΔＴvhを超えないようにしている。そしてさらに、該許容駆動トルクΔＴvhの範囲内となるよう、最大限許容される許容エンジントルクΔＴeaをギヤ比Ｇrに応じて設定するようにしているのである。これにより、変速段が如何なる位置であっても、変速段に拘わらずエンジントルクが常に過不足なく良好なものとされる。
【００３７】
次のステップＳ２２では、許容燃料変化量ΔＱa演算部４４において、上記許容エンジントルクΔＴeaに基づいて許容燃料変化量（第２の燃料量）ΔＱa(n)を演算する。
【００３８】
ここで、図５を参照すると、コモンレール型のディーゼルエンジンにおける燃料量ＱとエンジントルクＴeと関係が示されているが、このように、コモンレール型のディーゼルエンジンでは、エンジン回転速度Ｎeに拘わらず、燃料量ＱとエンジントルクＴeとは比例関係となっている。つまり、燃料量Ｑの増加に応じてエンジントルクＴeが一定の増加率、即ちトルク係数Ｋで増加するようにされている。
【００３９】
故に、許容燃料変化量ΔＱa(n)と許容エンジントルクΔＴeaも比例関係にあり、許容燃料変化量ΔＱa(n)は次式(4)より容易に演算される。
【００４０】
ΔＱa(n)＝ΔＴea／Ｋ …(4)
このように許容燃料変化量ΔＱa(n)が算出されたら、ステップＳ２４では、比較部３４において、上記ステップＳ１４で求めた燃料変化量ΔＱt(n)と当該許容燃料変化量ΔＱa(n)とを比較する。実際には、加速、減速に応じて燃料変化量ΔＱt(n)の符号は異なるため、ここでは燃料変化量ΔＱt(n)の絶対値｜ΔＱt(n)｜と許容燃料変化量ΔＱa(n)との比較を行う。
【００４１】
ステップＳ２４の判別結果が真（Ｙｅｓ）で、｜ΔＱt(n)｜がΔＱa(n)より大の場合には、次にステップＳ２６に進み、燃料量Ｑ設定部３６において、加速状態にあって燃料変化量ΔＱt(n)の値が正であるか否か、或いは減速状態にあって燃料変化量ΔＱt(n)の値が負であるか否かを判別する。
【００４２】
該ステップＳ２６の判別結果が真（Ｙｅｓ）で、加速状態にあって燃料変化量ΔＱt(n)の値が正と判定された場合には、ステップＳ２８に進み、次式(5)より燃料量Ｑ(n)を演算する。
【００４３】
Ｑ(n)＝Ｑ(n-1)＋ΔＱa(n) …(5)
一方、ステップＳ２６の判別結果が偽（Ｎｏ）で、減速状態にあって燃料変化量ΔＱt(n)の値が負と判定された場合には、ステップＳ３０に進み、次式(6)より燃料量Ｑ(n)を演算する。
【００４４】
Ｑ(n)＝Ｑ(n-1)−ΔＱa(n) …(6)
つまり、ステップＳ２４の判別結果が真（Ｙｅｓ）で、燃料変化量ΔＱt(n)が許容燃料変化量ΔＱa(n)を超える程急激な変化をしているような場合には、燃料変化量ΔＱt(n)に応じた燃料噴射を行うと加速ショック或いは減速ショックが発生する虞があるため、この場合には、ステップＳ２８、ステップＳ３０を実行し、一実行周期（当該ルーチンの実行周期）当たりの燃料変化量（増加量または減少量）を許容燃料変化量ΔＱa(n)に抑えるようにする。
【００４５】
これにより、次のステップＳ３２では、最終的に燃料噴射量ＴＱ設定部３８において、燃料噴射量ＴＱ(n)が上記燃料量Ｑ(n)とコモンレール圧Ｐcとに基づき設定され、該当する燃料噴射弁２に向けて出力されることになるが、燃料噴射弁２から噴射される燃料が徐々に変化することとなり、加速時及び減速時におけるショックが低減される。
【００４６】
一方、ステップＳ２４の判別結果が偽（Ｎｏ）で、燃料変化量ΔＱt(n)の絶対値｜ΔＱt(n)｜が許容燃料変化量ΔＱa(n)以下の場合には、加速ショックや減速ショックが発生する虞はないと判断でき、この場合には、ステップＳ３６に進み、次式(7)に基づいて通常通り燃料量Ｑ(n)を演算する。
【００４７】
Ｑ(n)＝Ｑ(n-1)＋ΔＱt(n) …(7)
そして、ステップＳ３４では、加減速が開始されてから所定時間（所定期間）ｔ1経過したか否かが判別される。判別結果が偽（Ｎｏ）で未だ所定時間ｔ1が経過していない場合には、ステップＳ１０に戻り、当該ルーチンを繰り返し実行する。
【００４８】
一方、ステップＳ３４の判別結果が真（Ｙｅｓ）で加減速の開始から所定時間ｔ1が経過したと判定された場合には、当該燃料制御を終了する。
【００４９】
つまり、加減速の開始から所定時間ｔ1が経過した場合には、もはやショックは発生しないと判断し、上記許容燃料変化量ΔＱa(n)ずつの増減を止めるようにし、目標燃料量Ｑt(n)に基づいて通常通り燃料変化量ΔＱt(n)ずつ燃料の増減を行うようにする。
【００５０】
以上説明したように、本発明のエンジンの燃料噴射制御装置では、許容駆動トルクΔＴvhを予め設定しておき、該許容駆動トルクΔＴvhに基づいてギヤ比Ｇrに応じた最適な許容エンジントルクΔＴeaを求めるようにしており（ステップＳ２０）、さらに該許容エンジントルクΔＴeaに基づいて許容燃料変化量ΔＱa(n)を設定するようにしている（ステップＳ２２）。
【００５１】
故に、図６を参照すると、上記燃料制御に基づき車両の加減速を行った場合の燃料量Ｑの時間変化がタイムチャートで示されており、目標燃料量Ｑtが破線で、変速段が例えば１速段のときの燃料量Ｑが実線で、また４速段である場合の燃料量Ｑが２点鎖線でそれぞれ示されているが、同図に示すように、車両の加速時に変速段が１速段である場合には、加速開始（ｔ0）から所定時間ｔ1が経過するまで燃料量Ｑが実行周期毎に許容燃料変化量ΔＱa1(n)ずつ緩やかに増加することとなり、一方、変速段が４速段である場合には、所定時間ｔ1が経過するまで燃料量Ｑが実行周期毎に許容燃料変化量ΔＱa4(n)ずつ比較的大きく増加することになる。
【００５２】
従って、１速段のようにギヤ比Ｇrが大きい場合には、燃料噴射量が極めて小さく絞られて急加速することなく加速ショックが良好に防止される一方、４速段のようにギヤ比Ｇrが小さい場合には、燃料噴射量が比較的大きなものとされ、加速ショックが防止されるのみならず、高速走行での加速時等において車両が加速不良なく良好に加速されることになる。
【００５３】
また、車両の減速時に変速段が１速段である場合には、燃料量Ｑが実行周期毎に許容燃料変化量ΔＱa1(n)ずつ緩やかに減少し、一方、変速段が４速段である場合には、燃料量Ｑが実行周期毎に許容燃料変化量ΔＱa4(n)ずつ比較的大きく減少する。
【００５４】
故に、１速段のようにギヤ比Ｇrが大きい場合には、燃料噴射量がゆっくりと絞られて減速ショックが良好に防止されることになる一方、４速段のようにギヤ比Ｇrが小さい場合には、燃料噴射量が比較的大きく減少させられ、減速ショックが防止されるのみならず、無駄な燃料消費が抑制されて燃料消費量の低減が図られる。
【００５５】
ところで、上記実施形態においてはコモンレール型のディーゼルエンジンを例に説明したが、本発明はエンジンの駆動力で駆動される分配型の燃料噴射ポンプを有したディーゼルエンジンにも適用可能である。
【００５６】
但し、当該分配型の燃料噴射ポンプを有したディーゼルエンジンでは、位置制御型のポンプを例にとって説明すると、図７に示すように、スリーブポジションＳＰとエンジントルクＴeとの関係において、トルク係数Ｋがエンジン回転速度Ｎe（例えば、Ｎe1，Ｎe2，Ｎe3，Ｎe4）に応じて異なった値（Ｋ1，Ｋ2，Ｋ3，Ｋ4）となっている（図中には代表としてＫ1，Ｋ4のみ表示）。故に、この場合には、上記トルク係数Ｋの代わりにエンジン回転速度Ｎeに応じてこれらの値（Ｋ1，Ｋ2，Ｋ3，Ｋ4）を用いるようにする。これにより上記同様の効果が得られることになる。
【００５７】
また、分配型の燃料噴射ポンプが時間制御型のポンプである場合であっても、燃料噴射量調整部制御パラメータを横軸にとるようにすれば、図７と同様のトルク係数を定義することができる。
【００５８】
また、ここでは、ディーゼルエンジンの場合について説明したが、上記の如く燃料量Ｑ（若しくは燃料噴射量調整部制御パラメータ）とエンジントルクＴeとの関係においてトルク係数を求めることができるようなエンジンであれば、エンジンは如何なるタイプのエンジンであってもよく、ディーゼルエンジンに限らずガソリンエンジンであっても同様の効果が得られる。
【００５９】
【発明の効果】
以上の説明で明らかなように、請求項１のエンジンの燃料噴射制御装置によれば、要求負荷情報に基づいて第１の燃料量を設定するとともに、要求負荷の変化が検出されたときには、駆動トルクが所定の許容駆動トルクとなるようギヤ比情報に応じて許容エンジントルクを設定し、該許容エンジントルクに応じた第２の燃料量を設定するようにし、第１の燃料量が第２の燃料量よりも大きいときには所定期間に亘り第２の燃料量に基づいて燃料を噴射するようにしている。
【００６０】
従って、要求負荷の変化量が大きいような場合であって、第１の燃料量が第２の燃料量よりも大きいような場合には、駆動トルクが所定の許容駆動トルクとなるようギヤ比に応じて燃料噴射量を過不足なく適正に設定することができる。故に、車両の加減速時において加減速ショックを低減することができるのみならず、加速時において加速不良を確実に防止でき、減速時において燃料消費量の悪化を確実に防止することができる。
【図面の簡単な説明】
【図１】車両に搭載されたディーゼルエンジンの燃料噴射系の概略構成を示す図である。
【図２】本発明に係るディーゼルエンジンの燃料噴射制御系を示す制御ブロック図である。
【図３】本発明に係る車両の加減速時における燃料制御の制御ルーチンを示すフローチャートの一部である。
【図４】図３のフローチャートに続く、燃料制御の制御ルーチンを示すフローチャートの残部である。
【図５】コモンレール型のディーゼルエンジンの燃料量ＱとエンジントルクＴeとの関係を示す図である。
【図６】図３及び図４の制御ルーチンに基づき車両の加減速を行った場合の燃料量Ｑの時間変化を示すタイムチャートであって、本発明の作用効果を説明する図である。
【図７】分配型の燃料噴射ポンプを有したディーゼルエンジンのスリーブポジションＳＰとエンジントルクＴeとの関係を示す図である。
【符号の説明】
２ 燃料噴射弁
６ コモンレール
１２ 燃料タンク
２０ 電子コントロールユニット（ＥＣＵ）
２２ アクセルポジションセンサ（ＡＰＳ，要求負荷検出手段）
２４ エンジン回転センサ
２６ 車速センサ
２８ コモンレール圧センサ
３０ 目標燃料量Ｑt設定部
３２ 燃料変化量ΔＱt演算部（第１の燃料量設定手段）
３４ 比較部（燃料噴射手段）
３６ 燃料量Ｑ設定部（燃料噴射手段）
３８ 燃料噴射量ＴＱ設定部（燃料噴射手段）
４０ ギヤ比Ｇr演算部（ギヤ比検出手段）
４２ 許容エンジントルクΔＴea演算部（許容エンジントルク設定手段）
４４ 許容燃料変化量ΔＱa演算部（第２の燃料量設定手段）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine fuel injection control device, and more particularly to a fuel injection control technique during acceleration / deceleration of a vehicle.
[0002]
[Related background]
Normally, in engine control of an engine mounted on a vehicle, the driver operates the accelerator pedal, and the fuel injection amount is varied according to the operation amount or a parameter (required load) correlated with the operation amount. Thus, the traveling state of the vehicle is controlled.
[0003]
However, in this case, when the accelerator pedal is suddenly operated greatly, the fuel injection amount suddenly increases or decreases accordingly, so that the engine load largely fluctuates and the fluctuation is transmitted to the vehicle body side. There is a problem that acceleration shock or deceleration shock occurs.
[0004]
Therefore, when the accelerator is suddenly opened, the accelerator opening at that time is recognized to be smaller than the actual accelerator opening, and fuel is injected in accordance with the accelerator opening recognized to be smaller, thereby suppressing the engine torque change. Is considered. In this case, when the shift speed is the first speed, that is, when the gear ratio is the largest, the torque change of the engine is large. Torque shock during acceleration is prevented by recognizing the accelerator opening and suppressing the fuel injection amount.
[0005]
In addition, when the accelerator is suddenly closed, the accelerator opening at that time is recognized to be larger than the actual accelerator opening, and fuel injection is continued to suppress a sudden drop in torque. Thus, it is considered to prevent a deceleration shock.
[0006]
[Problems to be solved by the invention]
However, if the fuel amount is set based on the case where the shift speed is the first speed so that no shock is generated when the accelerator is suddenly opened and closed as in the prior art described above, the speed is greater than the second speed. However, when the gear ratio is small, for example, there is a problem that acceleration failure occurs when the accelerator is suddenly opened, and fuel is unnecessarily supplied when the accelerator is suddenly closed.
[0007]
On the other hand, as disclosed in Japanese Examined Patent Publication No. 4-54816, the fuel injection pulse width that determines the fuel injection amount at the time of acceleration is reduced to reduce shock and reduce the reduction amount according to the shift stage. Although the technique of correcting is known, this technique is intended only to reduce the acceleration / deceleration shock, and the correction amount is set in advance for each shift stage so as not to generate a shock. . Therefore, the technique disclosed in the publication is not preferable because there is a possibility that an acceleration failure may occur when the accelerator is suddenly opened as described above, and fuel may be unnecessarily supplied when the accelerator is suddenly closed.
[0008]
The present invention has been made based on the above-described circumstances, and an object of the present invention is to provide an engine fuel injection control device that does not cause acceleration / deceleration shocks during acceleration / deceleration of a vehicle, and that does not cause poor acceleration or deteriorate fuel consumption. There is.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the first fuel amount is set by the first fuel amount setting means based on the output from the required load detection means, and the gear ratio detection means. When the change in the required load is detected by the required load detection means, the allowable engine torque setting means responds to the gear ratio information so that the drive torque becomes a predetermined allowable drive torque. The allowable engine torque is set, and the second fuel amount is set by the second fuel amount setting means according to the allowable engine torque. Then, the first fuel amount is compared with the second fuel amount. When the first fuel amount is larger than the second fuel amount, the fuel injection means sets the second fuel amount over a predetermined period. Based on this, fuel is injected.
[0010]
As a result, when the change amount of the required load is large and the first fuel amount is larger than the second fuel amount, the gear ratio is set so that the drive torque becomes a predetermined allowable drive torque. Accordingly, the fuel injection amount is appropriately set without excess or deficiency, acceleration / deceleration shock is reduced during acceleration / deceleration of the vehicle, acceleration failure is suitably prevented during acceleration, and fuel consumption is reduced during deceleration. Deterioration is preferably prevented.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0012]
Referring to FIG. 1, there is shown a schematic configuration of a fuel injection system of a diesel engine mounted on a vehicle, and with reference to FIG. 2, a control block diagram of the fuel injection control system of the diesel engine according to the present invention. Hereinafter, the configuration of the fuel injection control device for an engine according to the present invention will be described with reference to these drawings.
[0013]
Here, a four-cylinder diesel engine (hereinafter simply referred to as an engine) whose fuel injection system is a common rail type will be described as an example.
[0014]
As shown in FIG. 1, a diesel engine main body (not shown) is provided with a fuel injection valve 2 for each cylinder, and the input ports of these fuel injection valves 2 are connected to a common rail via fuel pipes 4 respectively. 6 is connected. A fuel pipe 7 is connected to the common rail 6, and the fuel pipe 7 is connected to a fuel tank 12 via a high pressure pump 8 and a low pressure pump 10.
[0015]
On the other hand, the return pipe 14 extends from the output port of the fuel injection valve 2 so as to merge with each other, and the return pipe 14 is also connected to the fuel tank 12. The fuel injection valve 2, the high pressure pump 8, and the low pressure pump 10 are electrically connected to the output side of an electronic control unit (ECU) 20.
[0016]
Further, a return pipe 16 is branched from the portion of the fuel pipe 7 between the low pressure pump 10 and the high pressure pump 8, and the return pipe 16 is connected to the return pipe 14 via a relief valve 17. Has been.
[0017]
As a result, when an ignition key (not shown) is operated and a motor drive signal is output from the ECU 20 to the low pressure pump 10 and the high pressure pump 8, the low pressure pump 10 and the high pressure pump 8 are operated, and the fuel is supplied to the fuel tank. 12 is supplied into the common rail 6 and is held and stored at a constant pressure in the common rail 6. When an operation signal is supplied from the ECU 20 to the fuel injection valve 2 for each cylinder according to the crank angle, the fuel stored in the common rail 6 is injected from the fuel injection valve 2 into the combustion chamber at a constant pressure. The The surplus fuel is returned to the fuel tank 12 through the return pipe 14.
[0018]
As shown in FIG. 2, an accelerator pedal (not shown) for controlling the output of the engine is connected to the input side of the fuel injection control device of the present invention in the ECU 20, and the accelerator opening (required load) θac is set. Acceleration position sensor (APS, required load detection means) 22 to detect, engine rotation sensor 24 to detect engine rotation speed Ne, vehicle speed sensor 26 to detect vehicle speed (vehicle speed) Vh, and pressure in the common rail 6 (common rail pressure) ) A common rail pressure sensor 28 for detecting Pc is connected, and the fuel injection valve 2 is connected to the output side as described above.
[0019]
Specifically, as shown in the figure, the accelerator opening information θac and the engine rotational speed information Ne are supplied to the target fuel amount Qt setting unit 30, and the output signal of the target fuel amount Qt setting unit 30 Is supplied to the comparison unit 34, the fuel amount Q setting unit 36, and the fuel injection amount TQ setting unit 38 (hereinafter referred to as fuel injection unit) via the fuel change amount ΔQt calculation unit (first fuel amount setting unit) 32. Has been.
[0020]
Further, the engine rotational speed information Ne and the vehicle speed information Vh are supplied to a gear ratio Gr calculating section (gear ratio detecting means) 40, and the output signal of the gear ratio Gr calculating section 40 is an allowable engine torque ΔTea. The data is input to the comparison unit 34 via a calculation unit (allowable engine torque setting means) 42 and an allowable fuel change amount ΔQa calculation unit (second fuel amount setting means) 44.
[0021]
The common rail pressure information Pc is supplied to the fuel injection amount TQ setting unit 38 so that the output signal of the fuel injection amount TQ setting unit 38 is finally supplied to the fuel injection valve 2. Has been.
[0022]
The engine is connected to drive wheels (both not shown) of the vehicle via a transmission, and the transmission is configured with, for example, five forward speeds.
[0023]
The operation and effect of the engine fuel injection control apparatus configured as described above will be described below.
[0024]
Referring to FIGS. 3 and 4, there is shown a flowchart of a processing routine of the fuel injection control device, that is, a control routine of fuel control (acceleration / deceleration fuel control) at the time of acceleration / deceleration of the vehicle. The effects of the fuel injection control device according to the present invention will be described.
[0025]
In step S10, first, the engine speed information Ne, accelerator opening information θac, vehicle speed information Vh, and common rail pressure information Pc are read from each sensor.
[0026]
In step S12, the target fuel amount Qt setting unit 30 sets the target fuel amount Qt (n) from the accelerator opening information θac and the engine speed information Ne. That is, in step S12, the target fuel amount at the time of acceleration / deceleration, that is, the target fuel amount Qt (n) is set from, for example, a map obtained in advance based on the accelerator opening information θac at the end of the accelerator pedal operation. . Hereinafter, the subscript (n) indicates a value obtained by the current routine execution.
[0027]
When the target fuel amount Qt (n) is set, in the next step S14, the fuel change amount ΔQt calculation unit 32 determines the fuel amount Q (n-1) at the previous execution cycle, that is, the previous routine execution, and the target value. Based on the fuel amount Qt (n), a fuel change amount (first fuel amount) ΔQt (n) is calculated from the following equation (1).
[0028]
ΔQt (n) = Qt (n) −Q (n−1) (1)
In step S16, the gear ratio Gr calculation unit 40 calculates the current gear ratio Gr from the engine rotational speed information Ne and the vehicle speed information Vh by the following equation (2).
[0029]
Gr = {Ne · 60 · 2 · π · Rw} / {1000 · Vh} (2)
Here, π is the circumferential ratio, and Rw is the tire radius of the vehicle.
[0030]
Further, based on the gear ratio Gr obtained by the calculation in this way, the current gear position is determined from, for example, Table 1 below. That is, since the gear ratio Gr obtained from the above equation (2) changes in accordance with the tire air pressure and the like, it is determined whether or not the calculated gear ratio Gr is within an allowable range set for each gear position. Thus, the transmission gear stage is uniquely determined, and the gear ratio Gr is fixed to a specific value of each gear stage (for example, Gr = 13.3 if the first gear stage).
[0031]
[Table 1]

In the next step S18, whether or not the gear ratio Gr calculated from the above equation (2) is within the range of the gear ratio Gr shown in Table 1 above and less than a value Gr1 (here, 16.5), That is, it is determined whether or not the calculated gear ratio Gr is equal to or greater than the value Gr1.
[0032]
If the determination result in step S18 is false (No) and the calculated gear ratio Gr is greater than or equal to the value Gr1 (16.5 above), the engine speed Ne is excessively increased from the above equation (2). That is, it can be determined that the engine is in an idling state. In such a case, it is determined that the gear position is in the neutral position. Then, when the gear position is in the neutral position in this way, a shock that causes a problem does not occur, and the routine is exited as it is.
[0033]
On the other hand, if the determination result in step S18 is true (Yes) and the calculated gear ratio Gr is less than the value Gr1 and is within the range shown in Table 1, the process proceeds to step S20.
[0034]
In step S20, the allowable engine torque ΔTea calculation unit 42 uses the following equation (Gr = 13.3, etc. for the first gear) corresponding to the specific gear ratio Gr determined based on Table 1 above (for example, Gr = 13.3). 3) Calculate the allowable engine torque ΔTea.
[0035]
ΔTea = ΔTvh / Gr (3)
Here, ΔTvh is a permissible drive torque (predetermined permissible drive torque) set in advance by experiments or the like so as not to cause a shock during acceleration / deceleration.
[0036]
Normally, a shock that occurs during acceleration / deceleration is caused by a drastic change in the drive torque. Therefore, in the present invention, first, the drive torque is not allowed to exceed the predetermined allowable drive torque ΔTvh. Yes. Further, the allowable engine torque ΔTea that is allowed to the maximum is set according to the gear ratio Gr so as to be within the range of the allowable drive torque ΔTvh. As a result, the engine torque is always good and good regardless of the gear position regardless of the gear position.
[0037]
In the next step S22, the allowable fuel change amount ΔQa calculation unit 44 calculates an allowable fuel change amount (second fuel amount) ΔQa (n) based on the allowable engine torque ΔTea.
[0038]
Here, referring to FIG. 5, the relationship between the fuel amount Q and the engine torque Te in the common rail type diesel engine is shown. In this way, in the common rail type diesel engine, regardless of the engine speed Ne, The fuel amount Q and the engine torque Te are in a proportional relationship. That is, the engine torque Te increases at a constant rate of increase, that is, the torque coefficient K as the fuel amount Q increases.
[0039]
Therefore, the allowable fuel change amount ΔQa (n) and the allowable engine torque ΔTea are also in a proportional relationship, and the allowable fuel change amount ΔQa (n) is easily calculated from the following equation (4).
[0040]
ΔQa (n) = ΔTea / K (4)
When the allowable fuel change amount ΔQa (n) is calculated in this way, in step S24, the comparison unit 34 calculates the fuel change amount ΔQt (n) obtained in step S14 and the allowable fuel change amount ΔQa (n). Compare. Actually, since the sign of the fuel change amount ΔQt (n) varies depending on acceleration and deceleration, the absolute value | ΔQt (n) | of the fuel change amount ΔQt (n) and the allowable fuel change amount ΔQa (n) are used here. Compare with.
[0041]
If the determination result in step S24 is true (Yes) and | ΔQt (n) | is larger than ΔQa (n), the process proceeds to step S26, and the fuel amount Q setting unit 36 is in an acceleration state. It is determined whether or not the value of the fuel change amount ΔQt (n) is positive or whether the value of the fuel change amount ΔQt (n) is negative in the deceleration state.
[0042]
If the determination result in step S26 is true (Yes) and the fuel change amount ΔQt (n) is determined to be positive in the acceleration state, the process proceeds to step S28, and the fuel amount is calculated from the following equation (5). Q (n) is calculated.
[0043]
Q (n) = Q (n-1) + ΔQa (n) (5)
On the other hand, if the determination result in step S26 is false (No), the vehicle is decelerating and it is determined that the value of the fuel change amount ΔQt (n) is negative, the process proceeds to step S30, and the fuel is calculated from the following equation (6). The quantity Q (n) is calculated.
[0044]
Q (n) = Q (n−1) −ΔQa (n) (6)
That is, if the determination result of step S24 is true (Yes) and the fuel change amount ΔQt (n) changes so rapidly that it exceeds the allowable fuel change amount ΔQa (n), the fuel change amount ΔQt If fuel injection according to (n) is performed, acceleration shock or deceleration shock may occur. In this case, step S28 and step S30 are executed, and per one execution cycle (execution cycle of the routine). The amount of change in fuel (increase or decrease) is suppressed to the allowable amount of change ΔQa (n).
[0045]
As a result, in the next step S32, the fuel injection amount TQ (n) is finally set in the fuel injection amount TQ setting unit 38 based on the fuel amount Q (n) and the common rail pressure Pc. Although it is output toward the valve 2, the fuel injected from the fuel injection valve 2 gradually changes, and shock during acceleration and deceleration is reduced.
[0046]
On the other hand, if the determination result in step S24 is false (No) and the absolute value | ΔQt (n) | of the fuel change amount ΔQt (n) is less than or equal to the allowable fuel change amount ΔQa (n), an acceleration shock or a deceleration shock In this case, the process proceeds to step S36, and the fuel amount Q (n) is calculated as usual based on the following equation (7).
[0047]
Q (n) = Q (n-1) + ΔQt (n) (7)
In step S34, it is determined whether or not a predetermined time (predetermined period) t1 has elapsed since the start of acceleration / deceleration. If the determination result is false (No) and the predetermined time t1 has not yet elapsed, the process returns to step S10 and the routine is repeatedly executed.
[0048]
On the other hand, if the determination result in step S34 is true (Yes) and it is determined that the predetermined time t1 has elapsed from the start of acceleration / deceleration, the fuel control is terminated.
[0049]
That is, when the predetermined time t1 has elapsed from the start of acceleration / deceleration, it is determined that the shock no longer occurs, and the increase / decrease in the allowable fuel change amount ΔQa (n) is stopped, and the target fuel amount Qt (n) Based on the above, the fuel is increased / decreased in increments of ΔQt (n) as usual.
[0050]
As described above, in the engine fuel injection control device of the present invention, the allowable drive torque ΔTvh is set in advance, and the optimum allowable engine torque ΔTea corresponding to the gear ratio Gr is obtained based on the allowable drive torque ΔTvh. In this manner (step S20), an allowable fuel change amount ΔQa (n) is set based on the allowable engine torque ΔTea (step S22).
[0051]
Therefore, referring to FIG. 6, the time change of the fuel amount Q when the vehicle is accelerated / decelerated based on the fuel control is shown in a time chart, the target fuel amount Qt is a broken line, and the shift stage is, for example, 1 The fuel amount Q at the speed stage is indicated by a solid line, and the fuel amount Q at the time of the fourth speed stage is indicated by a two-dot chain line. As shown in FIG. In the case of a high gear, the fuel amount Q gradually increases by an allowable fuel change amount ΔQa1 (n) every execution cycle until a predetermined time t1 elapses from the start of acceleration (t0), while the shift gear is In the case of the fourth speed stage, the fuel amount Q is relatively increased by the allowable fuel change amount ΔQa4 (n) every execution cycle until the predetermined time t1 elapses.
[0052]
Therefore, when the gear ratio Gr is large as in the first gear, the fuel injection amount is reduced to a very small value, so that an acceleration shock can be prevented well without sudden acceleration, while the gear ratio Gr as in the fourth gear. Is small, the fuel injection amount is relatively large, and not only acceleration shock is prevented, but also the vehicle is accelerated well without acceleration failure during acceleration at high speeds.
[0053]
Further, when the gear stage is at the first speed when the vehicle is decelerated, the fuel amount Q gradually decreases by the allowable fuel change amount ΔQa1 (n) every execution cycle, while the gear stage is at the fourth speed stage. In this case, the fuel amount Q decreases relatively large by the allowable fuel change amount ΔQa4 (n) every execution cycle.
[0054]
Therefore, when the gear ratio Gr is large as in the first gear, the fuel injection amount is slowly throttled and the deceleration shock is prevented well, while the gear ratio Gr is small as in the fourth gear. In this case, the fuel injection amount is relatively reduced, and not only the deceleration shock is prevented, but also wasteful fuel consumption is suppressed, and the fuel consumption amount is reduced.
[0055]
In the above embodiment, the common rail type diesel engine has been described as an example. However, the present invention is also applicable to a diesel engine having a distribution type fuel injection pump driven by the driving force of the engine.
[0056]
However, in the diesel engine having the distribution type fuel injection pump, the position control type pump will be described as an example. As shown in FIG. 7, in the relationship between the sleeve position SP and the engine torque Te, the torque coefficient K is Different values (K1, K2, K3, K4) are shown depending on the engine speed Ne (for example, Ne1, Ne2, Ne3, Ne4) (only K1, K4 are shown as representatives in the figure). Therefore, in this case, these values (K1, K2, K3, K4) are used according to the engine speed Ne instead of the torque coefficient K. As a result, the same effect as described above can be obtained.
[0057]
Even if the distribution type fuel injection pump is a time control type pump, if the control parameter for the fuel injection amount adjustment unit is taken on the horizontal axis, the same torque coefficient as in FIG. 7 should be defined. Can do.
[0058]
In addition, although the case of a diesel engine has been described here, any engine that can obtain a torque coefficient in the relationship between the fuel amount Q (or the fuel injection amount adjusting unit control parameter) and the engine torque Te as described above. For example, the engine may be any type of engine, and the same effect can be obtained not only with a diesel engine but also with a gasoline engine.
[0059]
【The invention's effect】
As is apparent from the above description, according to the fuel injection control device for an engine of claim 1, the first fuel amount is set based on the required load information, and when the change in the required load is detected, the driving is performed. The allowable engine torque is set according to the gear ratio information so that the torque becomes a predetermined allowable drive torque, the second fuel amount is set according to the allowable engine torque, and the first fuel amount is equal to the second fuel amount. When the fuel amount is larger than the fuel amount, the fuel is injected based on the second fuel amount over a predetermined period.
[0060]
Therefore, when the change amount of the required load is large and the first fuel amount is larger than the second fuel amount, the gear ratio is set so that the drive torque becomes a predetermined allowable drive torque. Accordingly, the fuel injection amount can be set appropriately without excess or deficiency. Therefore, not only the acceleration / deceleration shock can be reduced at the time of acceleration / deceleration of the vehicle, but also the acceleration failure can be surely prevented at the time of acceleration, and the deterioration of the fuel consumption can be surely prevented at the time of deceleration.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a fuel injection system of a diesel engine mounted on a vehicle.
FIG. 2 is a control block diagram showing a fuel injection control system of a diesel engine according to the present invention.
FIG. 3 is a part of a flowchart showing a control routine of fuel control during acceleration / deceleration of the vehicle according to the present invention.
FIG. 4 is a remaining part of the flowchart showing the control routine of the fuel control following the flowchart of FIG. 3;
FIG. 5 is a diagram showing a relationship between a fuel amount Q and an engine torque Te of a common rail type diesel engine.
6 is a time chart showing the time change of the fuel amount Q when the vehicle is accelerated / decelerated based on the control routine of FIGS. 3 and 4, and is a view for explaining the operation and effect of the present invention. FIG.
FIG. 7 is a diagram showing a relationship between a sleeve position SP and an engine torque Te of a diesel engine having a distribution type fuel injection pump.
[Explanation of symbols]
2 Fuel injection valve 6 Common rail 12 Fuel tank 20 Electronic control unit (ECU)
22 Accelerator position sensor (APS, required load detection means)
24 engine rotation sensor 26 vehicle speed sensor 28 common rail pressure sensor 30 target fuel amount Qt setting unit 32 fuel change amount ΔQt calculation unit (first fuel amount setting means)
34 Comparison part (fuel injection means)
36 Fuel quantity Q setting unit (fuel injection means)
38 Fuel injection amount TQ setting section (fuel injection means)
40 Gear ratio Gr calculation section (gear ratio detection means)
42 Allowable engine torque ΔTea calculation unit (allowable engine torque setting means)
44 Allowable fuel change amount ΔQa calculation section (second fuel amount setting means)

Claims (1)

Requested load detection means for detecting the requested load requested by the driver;
First fuel amount setting means for setting a first fuel amount based on an output from the required load detection means;
Gear ratio detecting means for detecting a gear ratio of the transmission;
An allowable engine torque setting that sets an allowable engine torque according to gear ratio information from the gear ratio detection means so that the drive torque becomes a predetermined allowable drive torque when a change in the required load is detected by the required load detection means. Means,
Second fuel amount setting means for setting a second fuel amount corresponding to the allowable engine torque set by the allowable engine torque setting means;
The first fuel amount set by the first fuel amount setting means is compared with the second fuel amount set by the second fuel amount setting means, and the first fuel amount is the second fuel amount. A fuel injection means for injecting fuel based on the second fuel amount for a predetermined period after a change in the required load is detected when
An engine fuel injection control device comprising:

Images