JPS58117346A - Device for controlling returning amount of exhaust gas of engine - Google Patents

Abstract

PURPOSE:To suppress the torque change at the time of restarting of fuel supply and to suppress the increase in noxious component in exhaust gas by returning the exhaust gas when the fuel supply is restarted after the stop of the fuel supply of the engine. CONSTITUTION:When the state of an engine is at the fuel supply restarting point t3, the time T for returning the exhaust gas returning is set. With the time T as a parameter, the duty of a pulse, which drives an EGR valve 90, is retrieved from a lookup table stored in ROM, and the opening degree of the EGR valve 90 is increased in approximately proportional to the increase in the duty. Thereafter, the returning amount of the exhaust gas is reduced with the elapse of time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine control device, and in particular to an exhaust recirculation amount control device.3 In order to efficiently control the engine and save the amount of fuel consumed, the present invention relates to an engine control device, and in particular to an exhaust recirculation amount control device. will be stopped. When the fuel supply is fully restarted upon completion of the deceleration state, the output torque of the engine suddenly changes from zero to a normal output torque state. This sudden change in torque causes a shock to the car and causes discomfort to the driver. In order to suppress this shock, when fuel supply is resumed, a control is performed to supply a smaller amount of fuel than the required amount of fuel, and gradually return the amount of fuel to the normal amount.

However, this control deteriorates the overall condition of the exhaust gas and increases harmful components. In order for the mixture to overcome the combustion phenomenon, it is necessary for the mixture ratio of air and fuel to fall within a certain range. When suppressing the amount of fuel and suppressing the shock when the supply is restarted, the mixture ratio deviates from the above combustion range, resulting in a situation where unburned gas is discharged. Furthermore, even if the fuel is within the combustion range, it is in an extremely lean state and ignites only near the spark plug, leaving the air-fuel mixture near the cylinder wall and piston top surface incompletely burned. Therefore, large amounts of carbon monoxide CO and hydrocarbons HC are contained in the exhaust gas.

The combustible range of the above mixture ratio becomes even narrower when the engine is at a low temperature. Therefore, after the engine has started, if the warm-up state has already ended but the engine system has not reached normal temperature, or if the fuel supply has been stopped for a long time and the temperature of the combustion chamber wall surface has decreased, Exhaust gas conditions will become even worse.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for masonry/engines that can suppress torque fluctuations when restarting fuel supply after stopping fuel supply to the engine, and also suppress increase in harmful components of exhaust gas.

The present invention is characterized in that exhaust gas is recirculated when the fuel supply to the engine is restarted after the fuel supply to the engine has been stopped, thereby suppressing fluctuations in the output torque of the engine. With this method, it is possible to control the mixture ratio of air and fuel within a range in which the combustion phenomenon occurs stably, and the content of harmful components in the exhaust gas can be kept low. The exhaust gas recirculation may be started at the same time as the fuel supply is restarted, or may be started before the fuel supply is restarted. When exhaust gas is recirculated during the fuel supply stop period, which is before the fuel supply is restarted, increasing the recirculation amount will make the engine brake less effective, but there is no problem unless the recirculation amount is increased.

The conventional method of reducing and gradually increasing the amount of fuel supplied when fuel supply is restarted results in an insufficient absolute amount of gas in the combustion chamber of the engine, and the temperature does not rise due to the compression process. Therefore, the temperature in the combustion chamber and the exhaust gas is rapidly lowered, thereby narrowing the above-mentioned range of combustible mixture ratios. Therefore, the components of hydrocarbons HC and carbon monoxide Co in the exhaust gas rapidly increase.

Furthermore, even if the engine has a catalytic converter, the temperature of the catalytic converter decreases due to a decrease in exhaust gas temperature.
Catalytic function decreases. Therefore, hydrocarbons HC and carbon monoxide Co in the exhaust gas are released into the atmosphere without being sufficiently reduced.

According to the present invention, nitrogen N, carbon dioxide CO2, water vapor 2H
Since the torque generated by the engine is suppressed by mixing an inert gas such as . Therefore, a stable combustion condition is obtained.

Furthermore, the recirculation of exhaust gas warms the intake air, promotes fuel vaporization, and contributes to stabilizing the combustion state. Further, in an engine having a catalytic converter, since the exhaust gas temperature does not decrease, the temperature of the catalytic converter can be prevented from decreasing, and the catalytic action can be prevented from decreasing.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an overall diagram of the engine system 1.

Intake air is air cleaner 2, throttle chamber 4, intake pipe 6 f: 4! ? , is supplied to the cylinder 8.

The gas burned in the cylinder 8 passes through an exhaust pipe 10 and is discharged into the atmosphere.

The throttle chamber 4 is provided with an injector 12 for injecting fuel.
The fuel ejected from the throttle chamber 4 is exposed in the air passage of the throttle chamber 4 and mixes with the intake air to form a complete air-fuel mixture.
It is supplied to the combustion chamber of cylinder 8.

A diaphragm 14 is provided near the outlet of the injector 12, and is configured to mechanically interlock with the accelerator pedal.
Driven by the driver. An air passage 22 is provided upstream of the throttle valve 14, and an electric heating element 24 that constitutes the entire thermal air flowmeter is disposed in this air passage 22. An electrical signal is extracted that varies depending on the determined air flow rate. Since the heating element 24 is provided within the air passage 22, it is protected from high-temperature gas generated when the cylinder 8 backfires, and is also protected from being contaminated by dust in the intake air. The outlet of this air passage 22 is opened near the narrowest part of the venturi, and the inlet thereof is opened on the -E flow side of the venturi.

The fuel supplied to the injector 12 is supplied to the fuel tank 30
The fuel is then supplied to a fuel pressure regulator 38 via a fuel pump 32, a fuel pump 34, and a filter 36. On the other hand, pressurized fuel is supplied from the fuel pressure regulator 38 to the injector 12 via the pipe 40, and the difference between the pressure in the intake pipe 6 through which fuel is injected from the injector 12 and the fuel pressure to the injector 12 is always constant. As shown, the fuel is returned from the fuel pressure regulator 38 through the return pipe 42 to the fuel tank 30, and the air-fuel mixture taken in from the intake valve 20 is compressed by the piston 50 and combusted by the spark from the ignition plug 52. Thermal energy is converted to kinetic energy. The cylinder 8 is cooled by cooling water 54, and the temperature of this cooling water is measured by a water temperature sensor 56, and this measured value is used as the engine temperature. A high voltage is supplied to the ignition plug 52 in accordance with the ignition timing of the ignition coil 58.

In addition, a reference angle signal REF and a position signal posi are sent to the crankshaft (not shown) at each reference crank angle and at each fixed angle (for example, 0.5 degrees) according to the rotation of the engine.
A crank angle sensor is provided.

The output of the crank angle sensor, the output of the water temperature sensor 56, and the electric signal from the heating element 24 are input to a control circuit 70 consisting of a microcomputer or the like and used for calculation processing.

A passage 26 is provided in the throttle chamber 4, bypassing the throttle valve 14e, and this passage is provided with a valve 62 whose opening degree can be controlled by the duty of the pulse current.

Further, a pulp 90 (hereinafter referred to as EGR pulp) for recirculating exhaust gas is provided between the intake pipe 6 and the exhaust pipe 100, and the valve opening degree changes depending on the duty of the applied pulse, thereby controlling the recirculation amount of exhaust gas. be done.

FIG. 2 is an overall configuration diagram of the control system.

CPU 102 and read-only memory 104 (hereinafter referred to as F)
tOM) and Random Access Memo IJ 10
6 (hereinafter referred to as RAM) and an input/output circuit 108. The CPU 102 calculates the input data from the input/output circuit 108 according to each program stored in the ROM 104, and returns the calculation result to the input/output circuit 108. Intermediate storage required for these operations is stored in R M106'! Use r box. CPU102. R,0M
Transfer of various data between the 104° FtAM 106 and the input/output circuit 108 is performed by a path line 110 consisting of a data bus, a control bus, and an address bus.

The input/output circuit 108 includes a first analog-to-digital converter (hereinafter referred to as ADCI and fe-j), a second analog-to-digital converter (hereinafter referred to as ADC2), an angle signal processing circuit 126, and a 1-bit ↑ stomach-a1. It has an input means with a screen read input/output circuit (hereinafter referred to as IO) for human output.

A battery voltage detector 132 (hereinafter referred to as VB) is connected to ADCl.
S), cooling water temperature sensor 56 (hereinafter referred to as TWS), atmospheric temperature sensor 112 (hereinafter referred to as TAS), adjustment voltage generator 114 (hereinafter referred to as vR8), and throttle angle sensor 116 (hereinafter referred to as θT). HS) and λ sensor 11
8 (hereinafter referred to as λS) is output from multiplexer 1.
20 (hereinafter referred to as FMPX), 'Jll was added, MP
One of these for X120:,i! ! and inputs it to the analog/digital conversion circuit 122 (hereinafter referred to as ADC). The digital value that is the output of the ADC 122 is held in a register 124 (hereinafter referred to as R, EG).

(9) In addition, the intake 9 empty Mtjt sensor 24 (hereinafter referred to as AFS) is input to the ADC 2, and is digitally converted via the analog-to-digital conversion circuit 1281 (with the ADC) and 7'L register 13o (hereinafter referred to as AFS). (noted as IG).

An angle sensor 146 (hereinafter referred to as ANGS) outputs a signal indicating a reference crank angle, for example, 180 degrees crank angle (hereinafter referred to as R
EF) and a signal (hereinafter referred to as PO8) indicating a minute angle, for example, a rank angle of 1 degree, are outputted and applied to the angle signal processing circuit 126, where they are shaped.

DIO has an idle switch 148 (hereinafter IDLE-
8W) and top gear switch 150 (hereinafter T)
Signals from the starter switch 152 (hereinafter referred to as STA a'l'-8W) are input.

Next, a pulse output circuit and a neighbor control object based on the performance results of the CPU will be explained. Injector control circuit (
(denoted as INJC) is a circuit that converts the calculation result into a digital pulse output. Therefore, (10) A pulse having a pulse width corresponding to the fuel injection amount is generated in INJC1 based on the data set in register INJD.
34 and applied to the injector 12 via an AND gate 136.

The ignition pulse generation circuit 138 (hereinafter referred to as IGNC) includes a register (hereinafter referred to as ADV) for setting the ignition timing and a register (hereinafter referred to as D) for setting the primary current supply start time of the ignition coil.
These data are set by the CPU. The ignition pulse generator 68 generates a pulse based on the set data and passes it through the AND gate 140.
generates an ignition pulse that controls the

The opening rate of the bypass valve 62 is determined by the control circuit (hereinafter referred to as 15CC).
) 142 through an AND gate 144.

l8CC1421'i Register l to set pulse width
Register l80 to set 5CD and repetition pulse period
I have P.

The EGRjt control pulse generation circuit 154 (hereinafter referred to as EGR, C) that controls the EGR control valve has a register EG that sets the 1 shift representing the pulse (11).
It has R, D, and a register EGRP for setting a value representing the frame return period of the pulse. This EGR,C output pulse is applied to the FOR,C driving transistor 9o via an AND gate 156f.

Further, the 1-bit input/output signal is controlled by the circuit DIO. Input signals are IDLE-8W signal, TOP
-8W double signal, 5TART-8W signal. Further, there is a pulse output signal for driving the fuel pump 32 as an output signal. This DIO has a register DDR for determining whether to use it as a full input terminal or an output terminal, and a register D for latching output data.
OUT is provided.

The register 160 is a register (hereinafter referred to as MOD) that holds instructions for commanding various states inside the input/output circuit 108.
For example, by setting an instruction in this register, 9.AND gate 136°140.144,156
It can be used to turn on or turn off all of the characters.

MOD like this (12) Can be controlled.

FIG. 3 is a program system diagram of the control circuit of FIG. 2. When the power switch is closed (by a key switch (not shown)), the CPU 102 enters the start mode and first starts the initialization program INITIALIZ 204.
Execute. Next, the monitoring program MONIT206=
2 Run background job f3AcK Gl'
Execute LOUND JOB208.

As this background job, for example, an E (3-Bit control task (hereinafter referred to as EGRC0N)) and a bypass cell 620 valve opening rate control task (hereinafter referred to as ISCCON) are executed.

During the execution of this TASK, when an interrupt factor (hereinafter referred to as IR,Q) occurs, the I
RQ factor analysis program 224 (hereinafter referred to as IR, Q ANA
(denoted as L) Execute all.

This II'tQ ANAL program is also ADC
1 end interrupt processing (hereinafter referred to as ADCt END IRQ) program 226 and ADC2 end interrupt processing (1
3) Program 228 (hereinafter referred to as ADC2END IRQ) and certain period elapsed interrupt processing (hereinafter referred to as INTVIR, Q)
This program consists of an engine stop interrupt processing (hereinafter referred to as BN8T IRQ) program and an engine stop interrupt processing (hereinafter referred to as BN8T IRQ) program, and issues a startup request (hereinafter referred to as QUEUE) to each task that requires activation, which will be described later.

This It (Q) Each program in the ANAL program 224 ADCIF, ND IR, Q 226 and ADC2
ENDIR, Q228-? INTV IR,Q23(
1) Each task to which an execution request QtJEUE is issued from each program is level zero task group 252 or level 1
These are a task group 254, a level 2 task group 256, and a level 3 task group 256. The task in which the engine start request QUEUE is generated by the ENST IRQ program 232 is the engine stop processing task 262 (hereinafter ENSTTA).
(denoted as SK). When this ENST TASK 262 is executed, the control system enters the start mode again and returns to the starting point 202.

The task scheduler 242 executes tasks starting from a task group with a higher level (here, level 0 is assumed to be strict) out of the task group in which the start request QUEUE has occurred or the task group whose execution has been interrupted (14). , determines the execution order of tasks. When the execution of the task group is completed, the completion report program 260 (hereinafter referred to as EXIT) reports the completion. Based on this completion report, the task group with the highest level among the task groups waiting for execution is executed next.

When there are no more suspended tasks or tasks for which a start request QUEUE has been issued, the task scheduler 242 reverts the CPU execution to the background job 208.
Move on to execution. Furthermore, if an IRQ occurs while any of the level 0 task group to level 3 task group is being executed, the process returns to the starting point 222 of the IRQ processing program. Please refer to the above INI'l'IALIZ for patent application No. 54-409014#jK.
204. MONIT206, BACK GFtOL
IND JOB206 IaQ ANAL224,
ENST TASK262. Task scheduler 242
, EXIT260 detailed programs are shown.

Next, the fuel supply stop task (hereinafter referred to as (15) FUEL cU'r TASK) shown in FIG. 4 will be explained.

This 'I' ASK ld is provided in the level 1 task 254 in FIG. 3, and is executed for a certain period of time, for example, every 20m5EC. In the level 0 task 252 of FIG. 3, the engine speed N and intake air amount Q are measured and the load TP is calculated. This load TP is expressed as fi Q / N, which is obtained by dividing the intake air amount Q by the engine rotational speed N. The load TP calculated in step 302 is compared with a predetermined value TPO. When smaller than the predetermined nfTPo, step 304
Execution moves to The relationship between the load and the fuel supply amount Ti tends to be as shown in FIG.

As the load TP decreases, the amount of fuel supplied decreases. .

If the engine rotation speed N is below a predetermined value TPO, it is determined whether fuel supply is unnecessary or not, and when the engine rotation speed N is high, the fuel supply is stopped. A determination based on the engine rotational speed N is made in the next step 304 and 306.

All fuel supply stop conditions are shown in FIG. Engine speed N
When NFC is greater than the predetermined value NFC, fuel supply is stopped. On the other hand, when the predetermined value NRC is exceeded, fuel (16) is supplied. Engine rotation speed N is a predetermined value & and NR,
There is a hysteresis region between the engine rotation speed and the predetermined value NPC, and when the engine speed decreases from a region greater than the predetermined value NPC, the fuel stop continues until the engine speed decreases to the predetermined value NRC.

On the other hand, if the engine rotation speed increases from a region smaller than the predetermined value NRC, the engine rotation speed 1F,N changes to the predetermined value NRC.
Continue fuel supply until FC is reached. This hysteresis area is controlled by a flag F'C provided in the RAM 106.
', is performed based on CUT.

At step 304 in FIG. 4, the engine rotational speed N is compared with a predetermined value NF'C, and if the predetermined value NF'C is greater than the predetermined value NF'C, execution proceeds to step 310. At step 310, the fuel supply amount, which is the data held by the INJC 134 in FIG. 2, is changed to zero. In step 312, the fuel supply stop message 9f is added.
e Flag in RAN 106 that means FG CU T
11''. Then jump to EXIT260 in FIG.

When the engine speed N is smaller than the peak value 304, C
The execution point of the PU 102 moves from step 304 to step 306 (17). In this step, the engine speed N is determined to be at a predetermined value NItC shown in FIG. In the state of small, execution moves to step 314 to restart fuel supply. On the other hand, since the engine rotational speed N is at the predetermined value NR,C shown in FIG. 6, the dog is in the hysteresis region, and the process moves to step 308 to determine the state of the flag FGCUT.

In step 308, the flag FGCUT' is searched, and when the flag 11'GCU T is "1", the fuel supply is stopped 1-
In order to continue, the process moves to step 310. Step 310
The value held in the INTDC 134 in FIG. 2 is rubbed by zero V. Furthermore, even if this held value was zero last time λ'' history δ, by changing it to zero this time, no malfunction will occur even if it is changed to zero multiple times.On the other hand, when flag Ii'CCU'l'' is "0" , EXIT 260 in FIG. 3 jumps to maintain the fuel supply state.

En//'s 54. iWi '1' When p is smaller than the predetermined value and the engine rotation speed is the predetermined value NR in FIG.
If the value is smaller than C, the execution moves to step 314 and the flag (
18) Check the contents of GuF'GCLIT. When FGCUT is "1", this is the moment of transition from stopping fuel supply to restarting fuel supply, and execution moves to steps 316 and 318 in preparation for restarting fuel supply. On the other hand, flag FGCIJ'
When "l" is "0#", the program jumps directly to E KIT 260 in FIG.

In step 316, a flag F' indicating a fuel supply restart state is set.
Change GR and C to 11'' and set flag F' GCIJ T
Change the contents of to "0". Then EXIT2 in Figure 3
After 60 hours, the TASK in Figure 4 ends.

FIG. 7 is an overall flow diagram of the level 1 task 254 of FIG. 3, which is executed every 20m5EC.

In step 402, check 111 whether the engine has completed starting.
iL, XIT260 hen jump from the start completion sharpening.

As in Japanese Patent Application No. 54-40901, only the calculation of the starting point of current flow to the ignition coil may be performed. Calculation of ignition timing and fuel supply 1iTi before the completion of engine starting is performed using μm1<INITIAL as described in Japanese Patent Application No. 1983-40901.
It is carried out in IZ204. At step 404 (19), flags FG and CUT are checked to determine whether the fuel supply is stopped. When flag FGCUT is “o2”,
fuel supply state, and in step 406 the engine speed N
, the intake air amount QA, and the fuel supply amount Ti. On the other hand, when the flag FGCUT is "1", the fuel supply is stopped and the fuel supply amount Ti is changed to zero in step 408. When the flag FGCLIT is changed to "1" in step 312 of FIG. 4, steps 404 and 408 of FIG.
Then the fuel supply i"r"i is changed to zero. Step 4
10, the Ti set in steps 406 and 408 is set to the second
Set to register INTD of INTC134 in the figure.

Due to this operation, the pulse width sent from the INTC 134 to the injector 12 via the gate 136 becomes zero when fuel supply is stopped, and the injector 12 does not open.

After step 410, the ignition timing and the starting point of the primary current of the ignition coil are calculated by the program IGN412, and the fourth
Execute puEr, cu'r TACK 414 detailed in the figure, and execute EXIT(20) 260 hejump as explained in FIG.

FIG. 8 shows a fuel supply restart task (hereinafter referred to as FUEL RECOVER) that constitutes the level 2 task 256 in FIG.

It is written as TASK. )'f: Explain. At step 420, the 7-lag FGRC is read from the RAM 106 and its contents are checked. In the resumed state after the fuel supply is stopped, this flag FOR,C is "1" and the process moves to step 422. On the other hand, when the flag FGaC is "0", EX
Shampoo IT260. FIG. 9 shows the relationship between the operating state of the engine and the states of flags FGCLIT and F'GFtC. In the fuel supply restart state, the flag panc is “1”
”. In step 422 of FIG. 8, it is determined whether or not timer T is zero. If timer T is zero, the engine state is at t3, which is when fuel supply is resumed. Therefore, the time for exhaust gas recirculation is To set T, step 4
The execution moves to 24, and timer '14 is set at a predetermined address in the RAM 106. On the other hand, if timer T is not zero,
Since timer T has already been set, step 426
Daigyo moves to. In this step, the duty of the pulse for driving the EGR valve 90 is searched using the lookup table stored in the ROM 106 using the timer T (21) as a parameter. Specifically, this value is a digital value representing the time width DT1 to DTn;
It shows the heavy pressure application time with respect to the repetition period TO of the pulse applied to the valve 90. When the time width DTfl is equal to the period TO, the duty of the pulse is maximum at 100%,
EGR, the curvature of the valve increases. FIG. 10 shows the relationship between the duty of the drive pulse and the opening degree of the EGR valve. The valve begins to open at the point where the duty reaches a slightly maximum value of 0%, and the valve opening increases approximately in proportion to the increase in duty.The opening reaches its maximum at 6° duty near 100%, indicating a saturation phenomenon. Even if the valve opening is fixed, the amount of exhaust gas recirculated varies depending on the negative pressure in the intake pipe. As shown in FIG. 10, the amount increases as the negative pressure increases. There are two conditions for restarting fuel supply. One is that TP is determined to be a dog based on a predetermined value in step 302 of the fourth section 1. In this case, the driver depresses the accelerator pedal, and the intake pipe negative pressure (22) shows a small value of 11 M'f. Therefore, the amount of exhaust gas recirculation is small relative to the duty of the drive pulse. However, in this first state, the IV driver requests a significant increase in the torque output of the engine, and the increase in torque due to both fuel supply openings is not a big problem. On the other hand, in the second case where fuel supply is restarted because the engine speed N has become smaller than the constant value NRC even though the engine load TP is smaller than the constant value TPO, the engine condition is very small.
The influence of torque fluctuations due to resumption of fuel supply is significant. However, in this second case, the intake pipe negative pressure is -500w)Tg~
The asthma value was -400 Hg and 1. Even if the duty of the drive pulse is small, the amount of exhaust gas recirculated is large. Therefore, torque fluctuations are small. The pulse duty D is searched using the timer T as a parameter in step 426 of FIG.
Tn is substantially determined by taking the above considerations into consideration. The pulse duty DT port retrieved in step 428 is set to E()RC1,54 in FIG.

Exhaust gas recirculation≠ is required to decrease over time (23) as shown in FIG. The relationship between the passage of time and the amount of exhaust gas recirculation is determined by the contents of the lookup table searched in step 426 of FIG. - In order to obtain the elapsed real time, in step 430, a constant value, for example "1", is subtracted from the value of timer T (it is defined as new T. In step 432, it is determined whether timer T is zero, If the value is zero, it is determined that the engine state has returned from the fuel supply restart state to the normal operating state, and the process proceeds to step 43.
4, the flag FGRC is reset. Then jump to EXIT. In steps 422, 430, and 432, a method was used in which the fuel supply restart state time was set and the remaining time was calculated. The state may be changed from the supply restart state to the normal operation state.

According to this embodiment, the exhaust gas is recirculated when the fuel supply is restarted, so that the intake pipe is warmed up, promoting vaporization of the fuel and stabilizing the fuel phenomenon. Therefore, the condition of the exhaust gas is good and there are few harmful components.

(24) Next, a second example, which is another example of this example, will be described. In order to further promote warming of the intake pipe, it is conceivable to recirculate the exhaust gas from time point 11, as shown in FIG. 9. In this case, the flag FGEGII is further used, and as shown in FIG.
#, and return to "01" at time 13.Flag FGEG
In order to set R, f to "1", all steps 450 are added to the flow of FIG. 4.

That is, after step 312, step 450 is executed and the flag FGEGR is changed to "1". Steps 452 and 454 are added after the determination in step 420 in FIG. When the execution moves to step 452, the flag FG is
Check EGRk. Since the flag FGEGR becomes "1" at time t1, the execution is at step 4 after time 11.
52, jumps to ETIT via step 454. Here, based on the flag PGEGR, Fig. 2 gGRC
The register EGRD of 154 is set to a constant value DTO'. As a result, as shown in FIG. 9, exhaust gas recirculation is started at time t1, and a predetermined amount of exhaust gas is recirculated. on the other hand(
25) Change the flag FGEGR to "0" at time t3 so that the engine state shifts to the fuel supply restart state at time t3. Step 456 is newly provided after step 424 in FIG. 8, and the flag FGEGFt is returned to "0". after that,
As mentioned above, in step 426, a new pulse duty 1 is set.
Since the current value is set to EGR, C154's Renstar EGFtD, the recirculation amount of exhaust gas is changed to a new value at time t3 as shown in FIG.

If exhaust gas is recirculated when fuel is stopped, the effectiveness of engine braking will be reduced. Therefore, it is sufficient to enter the exhaust gas recirculation control earlier than the response delay time of the EGR valve and to bring the intake pipe into the warm-up state, and there is no need to shift to the exhaust gas recirculation state sooner than necessary.

The third embodiment takes this point into consideration. Instead of moving to the exhaust gas recirculation state at time 1 in FIG. 9, at time t
2. Move to exhaust gas recirculation state. This time point 2 is, for example, the time when the engine/rotational speed NEGR is reached. Therefore, as shown in FIG. 4, all steps 460 are added. After entering the fuel stop state at time t1, the engine rotational speed reaches a predetermined value NEGR.

(26) In the above case, proceed to EXIT from step 460. On the other hand, when the engine rotation speed N becomes smaller than the quoted price NEG[t, the execution moves from step 460 to step 450, and in step 450, the flag PGEGR is set to "1".
As shown in FIG. 9, exhaust gas recirculation is started at time t2.The subsequent operation is the same as described in the second embodiment.

In this third embodiment, the exhaust gas is recirculated at time 12, which is just before the engine enters the fuel supply restart state, so that it does not affect the engine brake.

Also, by determining the engine rotation failure at time t2,
When the fuel supply is stopped for a long time, such as when the car is going down a hill,
The engine speed is gradually reduced, and the time between time t2 and power 3 becomes longer, allowing sufficient warm-up. On the other hand, in driving such as stopping at an intersection, the fuel supply stop time between 11 and 13 is short,
There is no need to warm up for a long time. In this case, the engine speed decreases relatively quickly, so that the period between times t2 and t13 is shortened.

Next, BACK GR, AUND JOB 20 in Figure 3
8(27) The details will be explained with reference to FIG. IDLE at step 510
-8W 148 judges whether it is ON or not. If it is ON, exhaust gas will not be recirculated. Therefore step 5
Proceed to step 12 and set the EGRI register to zero. In step 514, the duty ratio of the air bypass valve 62 is determined according to the cooling water temperature, and in step 516, this duty ratio is set to 1I8cD. Depending on this setting, engine air bypass installation is determined. Upon completion of step 516, the process returns to step 510, and unless a request for interrupt service to the CPU is issued,
This closed loop process is repeated.

On the other hand, when IDLE-8W becomes OFF'F, engine speed control m1sc is not performed. Therefore, in step 518, l
Set zero to 5CD register. Further, in this state, the EGR amount is calculated. Therefore, it is determined in step 520 whether the cooling water temperature TW is higher than the constant temperature TAc. If it is high, the process goes to step 524 to set zero to the 4')-1EGRD register. Also, if the water temperature TW is lower than the constant value TA, step 5
Proceed to step 22, determine whether the constant temperature is lower than TB,
Even if it is low, use EGRkCUT. Therefore step 524
Go to and set all zeros to EGRD. The predetermined 1iIiTA of step 520 sets the upper temperature limit while step 522
The predetermined value TB of 0 indicates the lower limit temperature, and EGRe is applied only when the temperature falls within this range. Therefore, if it is within this period, the process proceeds to step 526, where the EGR amount is calculated from the intake air amount QA and the engine rotational speed N by table search.

This search value is set to the EG, R, D lane stars in step 528. As a result, the EGR valve opens at a value determined by the duty ratio of the EGR, D register and the EGRP register set in advance, and exhaust gas recirculation is performed.

In the flowchart shown in FIG. 11, step 530
Alternatively, upon completion of step 516, repeat step 5.
Return to 10. By doing this, the ti calculator can be used to display the flowchart from step 510 to step 516 (29) for controlling the air bypass valve 62 or from step 518 to step 528 for controlling EGRi. Always run the flowchart. Therefore, assuming that no interrupt service request occurs, the program restarted from point 202 passes through the INI'l'IALIZ program 204 and the MONI'l' program 206 to the background job 208, the l8CCO program or EGR. , CON program will continue to be executed. Note that the program in FIG. 11 is in a fully open loop from step 510 to steps 524 and 528,
It is also possible to provide it in FIG. 8 as step 480 in FIG.

According to the present invention, the fuel mixture ratio can be set within a range in which the combustion phenomenon occurs stably, so that harmful components of exhaust gas are reduced.

[Brief explanation of drawings]

Figure 1 is an overall diagram of the engine system, Figure 2 is an overall configuration diagram of the control system, Figure 3 is a program system diagram, and Figure 4 is a detailed flowchart of the fuel supply stop task (30) - chart diagram, load TP and A characteristic diagram showing the relationship with the fuel supply situation Ti, FIG. 6 is a fuel supply stop state f, an operation explanatory diagram to explain, FIG. 7 is an overall flowchart of the level 1 task 402 in FIG. 3, and FIG. 8 is a fuel A detailed flowchart of the supply restart task, FIG. 9 is an explanatory diagram of engine fuel stop and fuel supply restart operations, and FIG. 10 is a characteristic showing the relationship between drive pulse duty, EG f't pen opening degree, and exhaust gas recirculation amount. 11 are detailed flowcharts of the pack ground job. 6... Intake pipe, 10... Exhaust pipe, 14... Throttle valve, 12... Injector, 52... Spark plug, 7
0... Control circuit, 90... EGR valve, 102...
...CPU, 104...ROM, 106...RAM
, 146...Crank angle sensor. Agent Patent attorney Akio Takahashi (31) Part F Figure 5 Tow 6 NRCNE6RNFC Enscene Kaitakumu tgN Figure 7
0 figure procedural amendment (sword sword) II/+ +l+ 5+l' PI 21f' Patent Office
Mugikanbian, U+Kan 4 Display of the Tono incident 1977; year f;'r+i'pl! fl 2nd IOCc
3 Relationship with person making amendment 4 mark 1 Patent applicant fl Location: Marunouchi, Chiyo 111-ku, Tokyo--Jth 5
Number 1 name f! iln+Co., Ltd. ↑1 [1.
Written by 11 kat Representative Wakazo 1) Katsu Shigeyo Makoto

Claims (1)

[Claims] 1. The operating state of the engine = f, then determine whether the detected operating state satisfies the fuel supply stop condition, and - based on the determination result of the fuel supply stop described in F,
engine control that stops the supply of fuel to the engine, further determines whether the detected operating state satisfies the conditions for restarting the fuel supply, and restarts the supply of fuel to the engine based on the result of the determination to restart the fuel supply. An exhaust gas recirculation amount control device for an engine, characterized in that exhaust gas is recirculated when fuel supply is restarted, and then the exhaust gas recirculation t is reduced.