JPS60173343A - Fuel injection control method of internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the fuel consumption ratio without extreme increase in discharge amount of NOx gas by supplying less fuel quantity of fuel for an engine when exhaust gas recirculation (EGR) is performed than the quantity thereof when no EGR is performed. CONSTITUTION:Intake air is controlled by a throttle valve 18 and sent into a combustion chamber 14 via a serge tank 20 and an intake valve 22. After the intake air is burnt in said combustion chamber, resultant exhaust gas is discharged into the atmosphere via an exhaust valve 24 and a catalyst converter 26. An EGR passage is connected between the tank 20 and an exhaust passage 16 and has an EGR valve 30 on the way of the connection. A sensor 38 detects a pressure inside the intake pipe and generates a voltage according to the detection, and a throttle position sensor 46 detects turning speed and opening of the valve 18. Crank angle sensors 42 and 44 disposed inside a distributor 40 generates pulse signals every time when a crank shaft makes 30 deg.- and 180 deg.-turn. No increase in discharge amount of NOx gas is provided under control of ECU36 while at the same time, fuel consumption ratio can be improved.

Description

Description: TECHNICAL FIELD The present invention relates to a method for integral control of fuel supply during acceleration of an internal combustion engine having an exhaust gas recirculation (EGR) system.

Prior Art Generally, in a fuel injection control device for an internal combustion engine, during acceleration,
Fuel injection pulse! The fuel supply amount is fully increased by performing an acceleration increase process that lengthens the fuel injection time or an asynchronous injection process that performs additional injections separately from normal fuel injection. In an engine equipped with an EGR system, the above-mentioned increase value during acceleration is set to such a value that the amount of NOx emissions can be kept low even when EGR is not being performed, such as during a cold start. However, when EGR is implemented, NO
Since the amount of x emitted is reduced, when acceleration is performed in this state, an unnecessarily large amount of fuel is supplied to the engine, and the fuel consumption rate increases accordingly.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel injection control method that can further reduce the fuel consumption rate without increasing the amount of NOx emissions.

Structure of the Invention A feature of the present invention that achieves the above-mentioned object is to provide an internal combustion engine which performs exhaust gas recirculation during predetermined operating conditions, while increasing the amount of fuel supplied to the engine during accelerated operating conditions. In the fuel injection control method, the amount of fuel supplied to the engine is reduced when exhaust gas is recirculated than when it is not recirculated.

Example The present invention will be described in detail below using the drawings.

FIG. 1 schematically represents an embodiment of the invention. In the figure, 10 is an engine body, 12 is an intake passage, 14 is a combustion chamber, and 16 is an exhaust passage. The flow rate of the intake air that is taken in when all the valves of the air cleaner (not shown) are taken is determined by the throttle valve 1 that is directly connected to the accelerator (not shown).
8. Intake air that has passed through the throttle valve 18 is guided into the combustion chamber 14 via a surge tank 20 and an intake valve 22. The exhaust gas after being combusted in the combustion chamber 14 is discharged into the atmosphere via the exhaust valve 24 and the exhaust passage 16, and further via the catalytic converter 26.

The EGR passage 28 is connected between the intake system surge tank 20 and the exhaust passage 16, and the gGR valve 3 is connected between the intake system surge tank 20 and the exhaust passage 16.
0 is set. The EGI (valve 30 is a diaphragm type valve, and intake pipe negative pressure is guided to the diaphragm chamber (not shown) via a negative pressure switching valve (VSV) 32 and a negative pressure conduit 34. The VSV 32 is a solenoid valve. It is turned on and off by a drive signal sent from an electronic control unit (ECU) 36.

A pressure sensor 38 is connected to the intake passage 12 downstream of the throttle valve 18 and detects the intake pipe negative pressure, in fact, the pressure inside the intake pipe, and generates a voltage corresponding to the detected value.

From the crank angle sensors 42 and 44 provided in the distributor 40, the crankshaft (not shown) is detected at 30°,
A Norse signal is output each time it rotates by 180°.

Is there a throttle eye on the rotating shaft of the throttle valve 18? A position sensor 46 is connected to the throttle valve 180 to detect rotation speed, opening degree, etc. of the throttle valve 180.

The water temperature sensor 47 detects the engine cooling water temperature, and outputs a voltage corresponding to the detected value.

The fuel injection valve 48 opens and closes in response to electrical drive pulses sent from the ECU 36, and intermittently injects pressurized fuel sent from a fuel supply system (not shown) into the air passage lz near the intake valve 22.

The gcIJ 36 includes an input/output interface 50, an analog/digital (kA) converter 52, and a central processing unit (CP).
U) 54, random access memory (RAM) 56
, and read-only memory (ROM) 58 etc.
7'c It mainly consists of a microconbeater. 7 pulse signals and detection signals from the crank angle sensors 42 and 44 and the throttle position sensor 46 are input to the microconbeater via the human output interface 50, while the drive signals and drive signals for the VSV 32 and fuel injection valve 48 are The 1,000 rus is outputted from the microcombinator via the input/output interface 50, respectively. The detection voltage from the pressure sensor 38 and water width sensor 47 is A/
The signal is applied to the D converter 52, sequentially converted into two communication signals, and then stored in the RAM 56.

No. 9 every 30 degrees of crank angle from the crank angle sensor 42
The rotational speed NE of the engine can be determined from the pulse signal.

This method is well known and will not be explained in detail, but for example, an interrupt can be made using this pulse signal, and the number of counts of the free run counter while the crank angle rotates by 30 degrees can be determined, and the rotation speed can be determined from the reciprocal number. Data regarding the requested rotational speed NE at which NE can be set is stored in the RAM 56.

The pulse signal every 1800 degrees of crank angle from the crank angle sensor 44 is used together with the Noculus signal every 30 degrees of crank angle to create various timing signals such as a fuel injection timing signal (in the case of acceleration increase processing method). It will be done.

FIG. 2 and FIG. 3 each show a part of the control zologram of the microcomputer in the ECU 36, and the operation of this embodiment will be explained below using these figures.

During the main processing routine, the CPU 54 executes the process shown in FIG. 2 to calculate the acceleration increase amount FAE. First, in step 60, it is determined whether or not the engine is in an accelerated operating state. Is this determination a throttle ruka? position switch 4
It may be determined whether the opening speed of the throttle valve 18 is equal to or higher than a predetermined value based on the signal from the pressure sensor 38.
It may be determined whether the increase system of the intake pipe internal pressure with respect to time is greater than or equal to a predetermined value based on data from the above. If there is a problem in the accelerated driving state, the following steps are all skipped and the next process (not shown) in the main process routine is performed. If it is determined that it is in an accelerated driving state, C in Stella 7'61.
1 Calculate the acceleration increase coefficient FAEo.

In this case, FAEo may be determined according to the degree of acceleration, or FAEo may be determined at certain times during acceleration.
,'! - It may be increased by a constant value.

In the next step 62, it is determined whether gGR is being performed. This is determined by sending a drive signal to the VSV 32 and determining whether or not the EGR valve 30 is open as a result. For example, if EGR is not being performed due to a cold start, etc., the process proceeds to step 63, where the acceleration increase coefficient FAE calculated in step 61, fr: is set as the final acceleration increase coefficient FAE, and the next step 64
Then, this FAE is stored in RA~156. If EGR is being performed, the process proceeds from step 62 to step 65, and the final acceleration increase coefficient FAB is set to a value smaller than FAE. That is, if K is a constant value smaller than 1.0, perform mk calculation of FAE = K - FAm, and convert this FAf8J to RAIV! with step 7'64. [Stored in 56.

On the other hand, the CPU 54 executes the entire processing routine shown in FIG. 3 at a predetermined crank angle position of 180° crank angle (in the case of a four-cylinder engine).

First, in step 70, the basic injection/main pulse width TP is determined from data representing the rotational speed NE and the intake pipe internal pressure Pf stored in the RAM 56 using a predetermined table. This method is well known. Next, in step 71, the final injection/nine pulse width TAU is calculated from the following equation from the acceleration increase coefficient obtained in the routine shown in FIG. 2 and the correction coefficients α and β.

TAU='rp-FAE・α+β Next, in step 72, this TAU'(i: RA
Store it in M56.

In response to a fuel injection timing signal occurring at a predetermined crank angle position other than 180°, an injection/J pulse signal having a duration corresponding to the injection pulse width TAU calculated as described above is formed, and this is output at the input/output interface 50. The pulse is converted into a driving pulse and sent to the fuel injection valve 48.

As a result, the interval corresponding to the pulse width TAU of the sweetfish injection valve 48 is
The TAU Kj is energized and this amount of fuel is supplied to the engine.

FIG. 4 shows part of a control program in another embodiment 1 of the present invention. In this embodiment, a so-called asynchronous injection process is performed in which fuel is injected separately from normal fuel injection during acceleration.

During the main processing routine, the CPU 54 executes the processing routine shown in FIG. Step 70 is the step in Figure 2,
It is exactly the same as f60. In step 71, the asynchronous injection and pulse width TAUA is used instead of the acceleration increase coefficient FAE.
Calculate to o'. The calculation method is FAE.

It is similar to The next step 72 is Stella f6 in Figure 2.
It is exactly the same as 2. In step 73, the final asynchronous injection pulse width TA is substituted for the final acceleration increase coefficient FAE.
Match UA to TAUA o. Then step 74
Instructs execution of asynchronous injection. This results in
The fuel injection valve 48 is energized for a period corresponding to TAUA, and the engine is additionally supplied with a month's worth of fuel corresponding to this TAUA. If EGR is being performed, in step 75, the final asynchronous injection/throttle width TAUA is set to TAUA.
TAUA = K-TAUAII (
However, it is set from K (1, 0) and the next step 74
Asynchronous injection is performed.

FIG. 5 shows a part of a control zologram in still another embodiment of the present invention. In this embodiment, the method of determining the acceleration increase coefficient Fl is different from that in FIG. 2. This processing routine is also performed during the main processing routine.

Step 80I'i is exactly the same as step 60 in FIG. 2, and if it is determined that the accelerating operation is in progress, the process proceeds to step 81. This Stella f81 is exactly the same as step 62 in FIG. If EGR is not being performed, the process advances from step 081 to stellar f82, and if EGR is being performed, the process advances to stellar f83. In step 82 or 83, the acceleration increase coefficient FA E2 or FA as shown in FIG.
Using a predetermined function representing F: and the degree of acceleration, an acceleration increase coefficient FAE corresponding to the degree of acceleration is determined.

In this case, the coefficient FAE when EGR is performed,
is always set to a smaller value than the coefficient FAK2 when it is not performed. Next, in step 84, the FAE is RA
Store in M56.

FIG. 7 is a part of a control glomodule according to still another embodiment of the present invention. This embodiment is different from the embodiment shown in FIG.
This is applied to the 3-injection process, and the operation number is clear from the above explanation, so the explanation will be omitted.

Effects of the Invention As explained in detail above, according to the present invention, during EGR, the amount of fuel supplied to the engine is smaller than when gGR is not being used, so the amount of NOx emissions does not increase significantly. Fuel consumption rate can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG. 2, FIG. 3,
Figures 4 and 5 are flowcharts of part of the control program, Figure 6 is a diagram showing the relationship between acceleration and acceleration increase coefficient or asynchronous injection pulse 1, and Figure 7 is a flowchart of part of the control program. It is. 10... Engine body, 12... Intake passage, 16...
Exhaust passage, 28... EGR passage, 30... EGR valve, 32... VSV, 34... Negative pressure conduit, 36...
ECU, 38... Pressure sensor, 42.44... Crank angle sensor, 46... Throttle position sensor, 48... Fuel injection valve, 50... Input/output interface, 52... A10 converter , 54 ・CPU,
56-=RAM, 5 B-ROM. Patent Applicant Toyota Motor Corporation Patent Attorney Patent Attorney T. Ki Akira Patent Attorney Kazuyuki Nishidate Patent Attorney Matsushita Patent Attorney Akira Yamaguchi Patent Attorney Masaya Nishiyama Figure 2 Figure 3 Figure 4 Acceleration ratio

Claims (1)

[Claims] 1. In a fuel injection control method for an internal combustion engine, in which exhaust gas is recirculated during a predetermined operating state, while the amount of fuel supplied to the engine is increased during an accelerating operating state, non-recirculation is performed during exhaust gas recirculation. A fuel injection control method for an internal combustion engine, characterized in that the amount of fuel supplied to the engine is reduced during circulation.