JPH02291446A - Fuel supply control device for turbocharged internal combustion engine - Google Patents

Abstract

PURPOSE:To avoid the overshoot of a basic fuel supply amount by limiting the basic fuel supply amount with a maximum fuel supply amount corresponding to a maximum basic fuel supply amount in the steady state operation of an internal combustion engine having a natural air intake system, when an engine load is accelerated from a level equal to or below the predetermined value. CONSTITUTION:The intake air amount of an internal combustion engine is detected with a intake air amount detection means A, and a basic fuel supply amount is set with a basic fuel supply amount setting means B on the basis of the detected result. In addition, a fuel supply control means C controls a fuel supply means D for supplying fuel on the basis of the set value. In the aforesaid device, the acceleration operation mode of the internal combustion engine is judged with an acceleration operation judgement means E. Also, when an engine load is equal to or less than the predetermined value in the initial judgement of acceleration, the maximum supply limit of the basic fuel supply amount is permitted with a maximum amount limit permission means F. Furthermore, the maximum fuel supply amount as a basic fuel supply amount when boost pressure in the downstream of an air intake throttle valve is approximately 0mmHg in the permitted acceleration operation mode of the internal combustion engine, is controled and corrected with a basic fuel supply amount maximum limit means G so as not be exceeded by the aforesaid basic fuel supply amount.

Description

[Detailed description of the invention] Industrial application field> The present invention relates to a fuel supply control device for an internal combustion engine with a supercharger,
More specifically, the present invention relates to a device that avoids erroneous setting of fuel supply amount due to an intake air flow rate detection error during engine acceleration.

<Prior art> As a fuel supply control device for an internal combustion engine, the Utility Model No. 61-1
As disclosed in Publication No. 83440, etc., the intake air flow scene Q and engine rotational speed N detected by an air flow meter
From that, the basic fuel supply amount Tp (= K X Q / N
; N is a constant), while this basic fuel supply amount T
The final fuel supply amount [i] is calculated by correcting p according to various operating conditions, and the fuel injection valve is injected with a pulse width corresponding to the fuel supply lTi in synchronization with the engine rotation. A device is known that is configured to intermittently supply fuel to an engine by outputting a pulse signal.

<Problems to be Solved by the Invention> However, in such a fuel supply control device, the basic fuel supply ffiTp is controlled based on the intake air flow rate Q detected by the air flow meter provided upstream of the intake throttle valve.
The following problems occurred during accelerated operation.

That is, an air flow make is provided upstream of the intake throttle valve,
In a vehicle that includes an intake collector section (volume chamber) downstream of the intake throttle valve, the air flow meter also detects the amount of air that fills the collector section during acceleration. However, when the fuel injection valve is provided in the intake port near the combustion chamber, is it possible to inject and supply fuel commensurate with the amount of air filled into the collector section, which is upstream of the fuel injection valve? Therefore, the amount of air for filling the collector is detected by the air flow meter, and the basic fuel supply fflT is determined based on the intake air flow ffiQ that includes the amount for filling the collector.
When p is calculated, this basic fuel supply amount Tp greatly exceeds the fuel amount required by the engine, which causes the problem that the air-fuel ratio becomes overrich during acceleration.

For this reason, in the past, a maximum basic fuel supply amount TP■8 was provided to limit the maximum value of the basic fuel injection amount Tp based on the intake air flow fiQ detected by the air flow meter, and the maximum basic fuel supply amount TP■8 was set when the engine was accelerated. Amount Tp■. When the basic fuel supply amount Tp exceeding the basic fuel supply ffiTp is calculated, the maximum amount TP+aa* is selected instead of this basic fuel supply ffiTp and the fuel supply is controlled, so that the collector The overshoot caused by the detection of the filling amount can be cut by the maximum basic fuel supply iTp8 (see Japanese Unexamined Patent Publication No. 62-247138, etc.).

By the way, the maximum basic fuel supply ft T P −ax
teeth,? Since it is determined based on the maximum basic fuel supply amount in the steady operating state when the engine is opened, the maximum basic fuel supply ITp is determined in the same way even in an internal combustion engine equipped with a supercharger.
■Once 8 is determined, in a supercharged internal combustion engine, the basic fuel injection fJTp increases during acceleration with the characteristics shown in Fig. 6, so the maximum basic fuel supply ITp■ corresponds to the collector filling amount. There was a problem that the overshoot could not be cut.

In other words, collector filling detection errors tend to occur when the engine accelerates from the low load side, and in supercharged internal combustion engines, boost pressure increases after there is a collector filling detection error. Therefore, if the maximum basic fuel supply amount TPsmx for cutting the collector filling amount is set in the same way as for natural intake, it will correspond to full-open steady state than the basic fuel injection ffiTp that corresponds to a collector filling error. The maximum basic fuel supply value T P l-11M increased and the collector filling error could not be cut.

The present invention has been made in view of the above-mentioned problems, and is designed to avoid an overshoot of the basic fuel supply amount due to the detection of the collector filling air amount in a supercharged internal combustion engine, and to improve the speed of acceleration during acceleration in the supercharged internal combustion engine. The purpose is to improve the air-fuel ratio controllability of the engine.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. An intake air flow rate detection means, provided in the intake port, detects the intake air flow rate upstream of the intake throttle valve of the engine, and a basic fuel supply amount setting means, which sets the basic fuel supply amount based on the detected intake air flow rate. and a fuel supply control means for driving and controlling the fuel supply means according to a fuel supply amount based on a set basic fuel supply amount, the fuel supply control device for a supercharged internal combustion engine comprising: an acceleration operation determination means for determining acceleration; and a maximum amount restriction permission means for permitting a maximum amount restriction of the basic fuel supply amount when the engine load is below a predetermined value the first time acceleration is determined by the acceleration operation determination means; The maximum amount of basic fuel supply when the boost pressure on the downstream side of the intake throttle valve is approximately Ommllg in the accelerating operation state of the engine in which the maximum amount restriction of the basic fuel supply amount is permitted by the maximum amount restriction permission means. A basic fuel supply amount maximum limiting means is provided for limiting and correcting the supply amount so that the supply amount does not exceed the basic fuel supply amount.

<Operation> In such a configuration, the supercharged internal combustion engine according to the present invention includes a volume chamber in the intake passage between the intake throttle valve of the engine and the engine, and also connects the fuel supply means to the intake port near the combustion chamber. In preparation for this, the intake air flow rate detection means is provided upstream of the intake throttle valve of the engine to detect the intake air flow rate. The amount of fuel detected and supplied by a fuel supply means provided downstream of the volume chamber does not need to be set in accordance with the amount of air filled in the volume chamber.

Here, the basic fuel supply amount setting means sets the basic fuel supply amount based on the intake air flow rate detected by the intake air flow rate detection means, and the fuel supply control means sets the basic fuel supply amount based on the fuel supply amount based on the basic fuel supply amount. The fuel supply is controlled by driving and controlling the fuel supply means.

Further, as a configuration according to the present invention, the acceleration operation determination means determines the acceleration operation state of the engine, and when the engine load is equal to or less than a predetermined value at the first time when acceleration is determined, the maximum amount restriction permission means Allow maximum amount limit of base fuel supply.

In the accelerating operating state of the engine in which the maximum amount restriction of the basic fuel supply amount is permitted by the maximum amount restriction permission means, the basic fuel supply amount cutting restriction means determines that the boost pressure downstream of the intake throttle valve is approximately OIllm. }Ig, the basic fuel supply amount is limited and corrected so that it does not exceed the maximum supply amount, which is the basic fuel supply amount.

In other words, when the engine is accelerated from a state where the engine load is below a predetermined value and no substantial supercharging is being performed, the maximum fuel supply amount corresponds to the maximum basic fuel supply amount during steady operation of a naturally aspirated internal combustion engine. The basic fuel supply amount is limited to cut the overshoot caused by the detection of the amount of air filled in the volume chamber (collector section).

Example Examples of the present invention will be described below.

In FIG. 2 showing the system configuration of one embodiment, an internal combustion engine 1 is equipped with an exhaust turbocharger (supercharger) 2. As shown in FIG. Here, the internal combustion engine l includes an air cleaner 3,
Intake duct 4, compressor 5, intercooler 6,
Air is taken in through the throttle chamber 7, collector section (volume chamber) 8, and intake manifold 9. The throttle chamber 7 is provided with a throttle valve (intake throttle valve) 10 that operates in conjunction with an accelerator pedal (not shown) to control the intake air flow IQ.

A throttle sensor 11 is attached to the throttle valve 10 as an acceleration operation determining means for detecting the opening degree TVO of the throttle valve 10. Further, an air flow meter 12 is provided in the intake duct 4 on the upstream side of the compressor 5 as an intake air flow rate detection means for detecting the intake air flow rate Q of the engine 1.

An electromagnetic fuel injection valve 13 serving as a fuel supply means is provided for each cylinder in the intake port portion of the intake manifold 9 near the combustion chamber of each cylinder, and these fuel injection valves 13 will be described later. The valve is opened by an injection pulse signal from a control unit 14 having a built-in microcomputer, and fuel is injected into the intake manifold 9, which is pressure-fed from a fuel pump (not shown) and adjusted to a predetermined pressure by a pressure regulator. Further, the exhaust gas from the engine 1 is configured to impart rotational energy to a turbine 15 supported coaxially with the compressor 5 before being discharged to the outside.

The control unit 14 detects the engine rotation speed N by counting the crank angle unit angle signal output from the crank angle sensor 16 in synchronization with the engine rotation for a certain period of time or by measuring the cycle of the crank angle reference angle signal.

In addition, a water temperature sensor 17 is provided to detect the cooling water temperature Tw, and the detection signal of this water temperature sensor 17 is inputted to the control unit 14 in the same way as the detection signals of the air flow meter 12, throttle sensor 11, etc.

The control unit 14 calculates the fuel injection amount Ti based on the operating state detected by each of the above-mentioned sensors, and drives and controls the fuel injection valve l3 based on the calculated fuel injection amount Ti.

Next, the calculation process of the fuel injection amount Ti performed by the control unit l4 will be explained according to the flowchart of FIG. Here, in this embodiment, basic fuel supply amount setting means, fuel supply control means. The functions as the basic fuel supply amount maximum limiting means and the maximum amount limiting permission means are as follows.
The software is provided as shown in the flowchart in the figure.

The routine shown in the flowchart of FIG. 3 is executed at minute intervals (for example, every LOMS), and the fuel injection amount (fuel supply amount) Ti is set by this routine.

First, step 1 (indicated as S1 in the figure).

The same applies hereafter), the intake air flow ffiQ detected by the air flow meter 12 and the engine rotation speed N. calculated based on the detection signal from the crank angle sensor 16. Throttle valve (intake throttle valve) 10 detected by throttle sensor 1l
Enter the opening degree TVO, etc.

In step 2, the intake air flow IQ input in step 1 is
Basic fuel injection +i (basic fuel supply amount) Tp is calculated based on and engine rotational speed N according to the following formula.

Tp''KXQ/N (K is a constant) In the next step 3, by subtracting the previous value from the throttle valve opening TVO manually input in Step 1, the opening change amount ΔTVO of the throttle valve 10 in the execution cycle of this routine is calculated. is calculated, and it is determined whether the amount of change ΔTVO is a value exceeding zero, that is, whether or not the engine l is in an accelerating state with the throttle valve 10 being opened.

Here, when ΔTVO≦0 and the throttle valve 10 is at a constant opening or is being closed (decelerated operation), the process proceeds to step 4 and the flag Ftr is set to zero.

On the other hand, if it is determined in step 3 that ΔTVO>0 and the throttle valve 10 is being operated to open, then step 5
Then, the flag Ftr is determined.

Since the flag Ftr is set to zero when ΔTVO≦0, the first time it is determined that ΔTVO>O, that is, the first time of acceleration detection, it is determined that the flag Ftr=O in step 5. ．． If it is the first acceleration and it is determined in step 5 that the flag Ftr=0, the process proceeds to step 6 and compares the basic fuel injection ITp calculated in step 2 this time with the reference injection amount Tps for low load determination. .

The reference injection amount Tps for low load determination is the basic fuel injection amount in a low load, low rotation state where the supercharging pressure by the exhaust turbocharger 2 is approximately Q mmHg and no substantial supercharging is performed by the exhaust turbocharger 2. It corresponds to injection MTp (engine load).

What is the basic fuel injection mTp for the first time of acceleration in step 6? When it is determined that the standard fuel injection fJTps is equal to or lower than the reference fuel injection fJTps, the process proceeds to step 7, where the maximum {! T set in advance for 'rp■8
Set p, ■. The maximum value TPm-x set in step 7 corresponds to the basic fuel injection + ftTp when the boost pressure is approximately OmmHg (see Figure 4). For example, this zero boost roughly corresponds to full throttle performance.

The basic fuel injection mTp at the first time of acceleration is the reference injection amount Tps.
As shown in Fig. 6, when the amount of fuel is below, an overshoot of the basic fuel injection lTp occurs due to incorrect detection of the collector filling amount, and this overshoot is caused by the basic fuel injection equivalent to 0 boost, as in the case of a naturally aspirated engine. If it is determined that Tp≦Tps because the fuel injection amount exceeds the injection amount Tp, the maximum value Tp■8 is set in step 7 so that the maximum basic fuel injection amount Tp is limited to the equivalent of 0 boost.

On the other hand, if it is determined in step 6 that the basic fuel injection amount Tp at the first time of acceleration exceeds the reference injection amount Tps, the process advances to step day and the maximum value Tp,%. Infinity ω to X
is set so that the maximum value of the basic fuel injection amount Tp is not actually limited by the maximum value TPIIsx.

This is the basic fuel injection amount Tp that exceeds the standard injection amount Tps.
(engine load), for example, in Fig. 4, when acceleration is from a boost pressure of -100 mmHg, the supercharging pressure is 108 mmHg and substantial supercharging is being performed, so the O Tpm corresponding to mmHg
m*, but this is not the result of erroneously detecting the amount of charged air in the collector section 8. If the maximum amount is limited by TpIIMI1 corresponding to Q mmHg, it will not be possible to supply the fuel required by the engine. be. As described above, the basic fuel injection amount Tp (
When the maximum value Tpsax is set based on the engine load), the flag Ftr is set to 1 in the next step 9, and when acceleration is continued, steps 5 to 1 are executed from next time.
Make it advance to 0.

? When the speed continues and the flag Ftr is determined to be 1 in step 5, the process proceeds to step 10, and the basic fuel injection g'rp,! ! : Maximum value TT
'msx and the calculated result is the maximum value Tp■,
If it exceeds the maximum value 'rp. ．． ．． is set to prevent the basic fuel injection mTp from being set exceeding the maximum value TPsax.

Note that the basic fuel injection amount TP at the initial stage of acceleration is the standard injection amount Tps.
When exceeding T, since the maximum value TP-am is set to infinity ω in step 8, T
P > T P m-x is not determined, and the maximum amount of basic fuel injection itTp is not substantially limited, but the basic fuel injection amount Tp at the initial stage of acceleration is equal to the reference injection ii.
When accelerating from a low load that is less than Tps, the overshoot of the basic fuel injection amount Tp due to erroneous detection of the collector filling air amount is cut off.

When the maximum amount is limited in this way and the basic fuel injection ITp is finally set, in the next step 12, various corrections are made to this basic fuel injection amount Tp according to the operating state of the engine l as follows. The final fuel injection amount (fuel supply i) Ti is calculated according to the equation.

T i 4-T P X C O E F XLAMB
Here, COEF is various correction coefficients mainly set based on the cooling water temperature Tw detected by the water temperature sensor 17, and LAMBDA is the air temperature detected via the oxygen concentration in the exhaust gas detected by an oxygen sensor (not shown). Feedback correction coefficient for controlling the fuel ratio to the target air-fuel ratio,
Ts is a correction amount for correcting a change in the effective valve opening time of the fuel injection valve 13 due to the voltage of an attached battery (not shown).

Then, at a predetermined fuel injection timing, an injection pulse signal with a pulse width corresponding to the latest calculated fuel injection amount Ti is output to the fuel injection valve l3, and the injection pulse signal is outputted to the fuel injection valve l3.
Fuel supply is controlled by driving the valve to open.

Although the engine 1 in this embodiment is equipped with an exhaust turbocharger 2, the type of supercharger is not limited, and it is clear that an engine-driven supercharger or the like may be used. .

<Effects of the Invention> As explained above, according to the present invention, in a supercharged internal combustion engine, overshoot of the basic fuel supply amount based on the detection of the amount of air charged into the volume chamber (collector section) during acceleration can be prevented. Since it can be corrected, the air-fuel ratio controllability during acceleration is improved, and there is an effect that the exhaust characteristics and acceleration performance during acceleration can be improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a system schematic diagram showing an embodiment of the invention, Fig. 3 is a flowchart showing control details in the above embodiment, and Fig. 4 is a supercharger. Diagrams showing the output characteristics of the internal combustion engine, Figures 5 and 6
Each figure is a time chart for explaining conventional control characteristics. 1... Engine 2... Exhaust turbocharger (supercharging a) 8... Collector part (volume chamber) 10
...Throttle valve (intake throttle valve) 11...Throttle sensor 12...Air flow meter l3...Fuel injection valve 14...Control unit l6...Crank angle sensor

Claims (1)

[Scope of Claims] A volume chamber is provided in the intake passage between the engine's intake throttle valve and the engine, and a fuel supply means is provided at the intake port near the combustion chamber, and the intake air flow rate upstream of the engine's intake throttle valve is controlled. an intake air flow rate detection means for detecting the intake air flow rate; a basic fuel supply amount setting means for setting a basic fuel supply amount based on the detected intake air flow rate; and a basic fuel supply amount setting means for setting the basic fuel supply amount based on the set basic fuel supply amount. A fuel supply control device for a supercharged internal combustion engine, comprising: a fuel supply control means for driving and controlling a supercharged internal combustion engine; an acceleration operation determination means for determining an acceleration operation state of the engine; maximum amount restriction permission means for permitting a maximum amount restriction of the basic fuel supply amount when the engine load is below a predetermined value the first time the engine load is applied; and a maximum amount restriction permission means for permitting the maximum amount restriction of the basic fuel supply amount In the accelerating operation state of the engine,
Basic fuel supply amount maximum limiting means is provided for limiting and correcting the basic fuel supply amount so that the basic fuel supply amount does not exceed the maximum supply amount that is the basic fuel supply amount when the boost pressure downstream of the intake throttle valve is approximately 0 mmHg. A fuel supply control device for an internal combustion engine with a supercharger, characterized in that: