JPS60195351A - Fuel supply control device in internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent deterioration of drivability and increase of NOX upon transition during acceleration, and as well to prevent the emission of HC, etc. during deceleration, by compensating the fuel injection amounts of main fuel injection valves toward rich and lean sides, respectively, upon change-over from injection by the main fuel injection valves alone to that by the main and auxiliaty fuel injection valves, vice versa. CONSTITUTION:As shown in the drawing in which the relationship between the time-elapse taken on the abscissa and the fuel injection amount (solid line) and as well the amount (broken line) of fuel introduced into a combustion chamber, taken on the ordinate is indicated, even though the injection of fuel is made in conformity with a demand for fuel injection amount as indicated by the solid line in order that acceleration is made at time t1 and then deceleration is made at time t5, the amount of introduced fuel varies, actually along the broken line. That is, a delay in response due to adhering fuel causes the mixture to be lean upon transient during acceleration. As a result there are offered problems of deterioration of drivability and increase of NOX which cause the engine to wheeze, be slow, and so forth. Meanwhile the mixture becomes rich upon transient during deleration, there is offered a problem of deterioration of emission of HC and CO. In order to eliminate the above-mentioned problems compensation for increase or decrease in fuel amount is made with the use of the amount of fuel injection from main fuel injection valves upon transient.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a fuel supply control device for an internal combustion engine that includes an auxiliary fuel injection valve for cooling intake air.

Prior Art In addition to the main fuel injection valve (simply referred to as the main injection valve) provided for each cylinder, there is also an auxiliary fuel injection valve (simply referred to as the auxiliary injection valve) located upstream of the intake pipe, for example, near the surge tank or the throttle valve. Internal combustion engines are already known. The fuel injection from the sub-injector cools the intake air, improving charging efficiency, and thus improving output performance. As a result, fuel injection by both the main and auxiliary fuel injection valves or fuel injection by only the main fuel injection valve is possible depending on the operating state. For example, when the load is above a certain level or when the rotational speed is above a certain level, both the main and sub-injectors can inject fuel, and in other cases, only the main injector can inject fuel.

However, since fuel injection control from the sub-injector has a response delay characteristic, there are various problems. To explain the intake characteristics of fuel injected from the sub-injector with reference to Fig. 1, the horizontal axis shows the passage of time, and the vertical axis shows the fuel injection amount (actual m) and the amount of fuel sucked into the combustion chamber. (dashed line)
shows. Now, time t! Accelerates at time t11, decelerates at time t11,
In the figure, it is assumed that there are many requests for fuel injection, as shown by the solid line, and that the sub-injector injects the fuel according to the request. But in this case,
The fuel is not drawn into the rectangular shape as shown by the solid line, but as shown by the broken line. Finally, at injection start time t1, only the atomized fuel (X in the figure) out of the injected fuel is taken in together with the intake air. Then, at time t2, the attached fuel reaches the combustion chamber with a delay, and gradually increases from time t2 to time t3. From time t3 to time t4, adhering fuel is also steadily sucked in. In this way, during the acceleration transition, there is a response delay of time t3-t relative to the required fuel amount, so the air-fuel ratio becomes lean. On the other hand, during deceleration transients, the opposite phenomenon occurs during acceleration transients.

At time t4, the mechanized fuel is cut,
In the figure, the amount of adhering fuel is reduced by Y, and from time t4 to time 1, adhering fuel is still sucked in steadily, and adhering fuel gradually decreases from time ts to time t6. In this way,
The air-fuel ratio becomes rich from time t4 to time t6.

Therefore, if the required fuel is simply distributed and supplied by the sub-injectors, the response delay of the adhering fuel will result in poor drivability such as lack of alignment, breathing, and sluggishness during transient acceleration, and NO
There are problems such as an increase in x, and on the other hand, there are problems such as deterioration of emissions of p, HC, and Co due to richness during deceleration transition.

Purpose of the Invention The purpose of the present invention is to solve the problems of the conventional type described above.
When switching from injection by the main injector to injection by the main and auxiliary injectors, the fuel injection amount of the main injector is corrected to the rich side,
By correcting the fuel injection amount of the main injector to the lean side when switching from injection by the auxiliary injector to injection by the main injector, it prevents deterioration of drivability such as breathing and sluggishness and increase in NOx during acceleration transients. On the other hand, during deceleration transition, I
C.

The purpose is to prevent the deterioration of CO emissions.

Structure of the Invention The structure of the present invention for achieving the above-mentioned objects is shown in FIG. That is, in addition to the main fuel injection valve provided for each cylinder, there is an auxiliary fuel injection valve provided in common for each cylinder in the upstream part of the intake passage, and depending on predetermined operating conditions and parameters, main fuel injection valve, 1ull fuel injection valve, etc. In an internal combustion engine in which a first fuel injection state by both injection valves and a second fuel injection state by only the main fuel injection valve are possible, the first switching means selects the first fuel injection state according to a predetermined operating state/parameter. The fuel injection state is switched from the first fuel injection state to the second fuel injection state, and during the transition of this switching, the fuel increasing means increases the injection amount of the main fuel injection valve. On the other hand, the second switching means switches from the second fuel injection state to the first fuel injection state in accordance with predetermined operating state parameters, and during the transition of this switching, the fuel reducing means controls the main fuel injection valve. This is to correct the injection amount by reducing it.

Example The present invention will be described in detail with reference to the drawings from FIG. 3 onwards.

FIG. 3 is an overall schematic diagram showing an embodiment of the fuel supply control device for an internal combustion engine according to the present invention. In Figure 3 1,
A 4-cylinder engine is assumed. That is, the main injection valves 3-1 (3-2, 3-3) are connected to the branch pipes 2 for each cylinder of the engine body 1.
, 3-4) are provided. Further, a sub-injection valve 5 is provided in, for example, a surge tank 4 of the collective intake pipe.

In other words, 1! The sub-injection valve 5 is common to each cylinder. Reference numeral 6 denotes an airflow meter that directly measures the amount of intake air and generates an analog voltage electrical signal proportional to the amount of intake air.

The guide tributary is provided with two rotation angle sensors 8.9 which generate an angular position M signal every time the shaft rotates, for example, 2 (720.degree. in terms of crank angle, 300 rotations).

The control circuit 10 processes signals from the air flow meter 6 and rotation angle sensors 8 and 9 to control the main injection valves 3-1 to 3-4 and the sub-injection valves 5, and includes, for example, a microcontroller. Consists of a beater.

FIG. 4 is a detailed block circuit diagram of the control circuit IO of FIG. 3. In FIG.
02.

Each of the pulse signals of rotation angles 8 and 9 is supplied to a timing generation circuit 103 for generating an interrupt request signal and a reference timing signal.

Further, the rotational angle sensor 9's signal is supplied to a predetermined position of the input interface 7/8 105 via the rotational speed forming circuit 104. The rotation speed forming circuit 104 has a rotation speed of 30°.
It consists of a dart that is controlled to open and close for each CA, and a counter that counts the number of pulses of the black and red signals CLK of the black and white generation circuit 106 that pass through this date, and therefore two communication signals that are inversely proportional to the rotational speed of the engine. will be formed.

The ROM 109 stores in advance a main routine, programs such as an interrupt routine to be described later, and various fixed data, constants, etc. necessary for these processes.

Latch circuit 111-1. Down counter 1.12-1,
Fligfloss 76113-1 and drive circuit 114
-1 is provided for the main injection valves 3-1 to 3-4, and the latch circuit 111-2, down counter 112-2, fritunoflora 7'113-2 and drive circuit 114-2 are provided for the sub injection valve 5. It is set up against. For example, when the injection amount data T of the sub-injection valve 5 is calculated, this data T is sent to the latch circuit 111 via the output interface 110.
-2. Next, when the injection start signal (strobe signal) S2 is generated at the injection start timing after a predetermined time, the data of the sub circuit 111-2 is reset to the down counter 112-2, and at the same time, the flip 70 is reset. 113-2 is set. As a result, the drive circuit 114-2 operates and the sub-injection valve 5 is energized. During this time, the down counter 112-2 performs clock counting,
Finally, when the carrier terminal of the down counter 112-2 reaches the l# level, the f-flop 7'113-2
is reset, and the drive circuit 113-2 stops energizing the sub-injection valve 5. The width injection valve 5 is energized for the above-mentioned fuel injection time T, so that an amount of additional fuel corresponding to the fuel injection time is sent into the combustion chamber of the engine body 1.

The operation of the control circuit 10 in FIG. 4 will be described with reference to charts 70 in FIGS. 5 and 6. Here, FIG. 5 is an acceleration determination routine, and FIG. 6 is a fuel injection calculation routine.

In step 501 of FIG. 5, the intake air amount Q of the air flow meter 6 is measured at a start step 502 at predetermined intervals.
i is taken in by the air flow meter 6, and the change in intake air amount ΔQ is calculated using the Stella f503 as ΔQ"Qi Qi-+, where Qi-1 is calculated based on the intake air amount 7"-ta from the previous calculation. In step 504, it is determined whether the intake air amount change ΔQ is greater than or equal to a predetermined value C, and in step 505
Then, it is determined whether the intake air amount change ΔQ is equal to or less than a predetermined value C/. If ΔQ≧C, it is determined that it is in an acceleration state and the
The acceleration state flag F1 is set in step 506, while the deceleration state flag F2 is cleared in step 507. ΔQ≦
-C', it is determined that it is a deceleration state, and at step 510 the acceleration state flag F1 is cleared, while the deceleration state flag F2 is set. If −C′<ΔQ<C, it is a steady state that is neither an acceleration state nor a deceleration state, so
, f 508 and 509, which flags Fl and F
Clear 2 as well. In step 512, Qto1←Qi is set in preparation for the next calculation, and in step 513 this routine ends.

In this way, it is established whether the engine is in an acceleration state, a deceleration state, or a steady state based on the flags Fl and F2.

Note that the above-mentioned acceleration/deceleration determination is based on changes in throttle valve opening,
This can also be done by changing the rotational speed or changing the pressure inside the intake pipe.

The start step PRO01 in FIG. 6 starts at every predetermined crank angle, for example, 1806CA. In step 602, it is determined whether or not the vehicle is in an acceleration state based on the flag Fl.

On the other hand, in Step 13, it is determined whether or not the vehicle is in a deceleration state based on the 7 lag F2.

Therefore, if it is in the acceleration state, the flow goes to Ste, Pro 03,
If it is in a deceleration state, the flow goes to ST, Pro 14, and if it is in a steady state, the flow goes to ST, ZORO 21.

Note that the counters N and N' correspond to the number of continuous rotations in the acceleration state and the number of continuous rotations in the deceleration state, respectively.

The acceleration state will be explained. In this case, Ste.

At f603, counter N is incremented, while at step 604, counter N/ is held at 0.

Next, Stella f605 determines whether N≦N1. If N≦N1, the fuel correction coefficient K is set in Step 06.
is set to 1 (>1). However, Kl is the intake air amount Q(
Strictly speaking, it is a value that depends on the intake air weight (Ga). Then, at step f610, the fuel injection amount qm of the main injection valves 3-1 to 3-4 and the fuel injection amount q11 of the sub-injection valve 5 are set to predetermined operating state parameters such as intake air amount data Q, rotational speed data Ne, etc. Further, step 611
The fuel injection amount of the main injector is increased by setting qm←Kqm. In step 612, qm and qs are converted into time and set in the child circuits 111-1 and 111-2, respectively.

This routine then ends at Stella 7°627.

If the acceleration state continues, the flow of step f606 is executed until the counter N reaches N, so the flow shown in FIG. 7(A)
As shown in , K=Kl is maintained.

Next, when the counter N reaches N1 while still in the acceleration state (corresponding to time t2 in Fig. 1), the flow changes to ST, ZORO 05
The process then proceeds to step 607, and -a is executed at N4-. Here, it is a constant value that satisfies a\i1<JK=Kl-1 (see FIG. 7(g)).

Note that steps 608 and 609 are for maintaining K at 1 or more. Flow then proceeds to step 610. In this way, the rotation of the engine progresses and the counter N
When is incremented, the correction coefficient gradually approaches 1, and finally when N=N, it is maintained at K=l. This corresponds to time t3 in FIG.

In this way, when the acceleration state is entered, step 61
At 0,611.612, the fuel injection amounts of both the main injection valve and the sub-injection valve are calculated, and the injection amount of the main injection valve is increased.

To explain the deceleration state, in this case, Ste.
4, the counter N' is incremented, and on the other hand, Ste, Zoro 1
At 5, the counter N is held at O.

Next, step 16 determines whether N/≦N1. If N'≦NI, the fuel correction coefficient K is set to Kz (<+) in step 617. In this! is also a value that depends on the intake air amount Q. Then, in step 624, only the fuel injection amount tm of the main injection valves 3-1 to 3-4 is calculated using the predetermined operating state and the main meter, such as the intake air amount data Q1 and the rotational speed data Ne. At 625, the amount of fuel injected from the injection valve is reduced by setting qm + - Kqm. Step 26 converts qm into time and sets it in the sub circuit 111-1. The routine then ends at step 627.

If the deceleration state continues, the flow of step 617 is executed until the counter N' reaches m, so that K=2 is maintained as shown in ω) in FIG.

Next, when the counter N' reaches Nl while remaining in the deceleration state (corresponding to time t6 in FIG. 1), the flow proceeds to step 61.
The process advances from step 6 to step 618, and 10a is executed at K←. Note that steps 619 and 620 are for keeping K at 1 or less. The flow then proceeds to step 624
Proceed to. In this manner, as the rotation of the engine progresses and the counter N' increments, the correction coefficient gradually approaches Vc1, and finally reaches N'-N'1 and is held at Kz1. This corresponds to time t6 in FIG.

In this way, when transitioning to the deceleration state, Ste, Zoro 2
At 4.625.626, the fuel injection amount of only the main injection valve is calculated, and at the same time, the injection amount of the main injection valve is reduced.

If the engine is in a steady state, neither in an acceleration state nor in a deceleration state, both counters N and N' are cleared in step 21.622, and the fuel correction coefficient is held at 1 in step 623. Neither the filler nor the main injection valve is increased or decreased.

As described above, when time-converted qm + qs is set in the latch circuits 111-1 and 111-2, respectively, the injection start signals SL and S generated at predetermined timings cause the υ latch circuits 111-1 and 111 to be set. -2 data is set in the down counters 112-1, 112-2, and injection is executed. Note that it is more advantageous in terms of the distribution ratio to control the injection start signal Sz so that it is generated when the intake air flow velocity near the sub-injection valve is high. Further, the normal injection start signal Sl is generated not every 180''CA but every 360°CA, and the main injection valves 3-1 to 3-4 inject simultaneously.

The above correction coefficient Kl r K! is fast, that is, Q is large and loss is small, so the value Δ==1 1=l Kz is determined as shown in FIG. Nl l Nz (or N:
. However, in the above embodiment, the values of N, , Nz are not directly determined, but are set to a constant value a.
determined by. It is therefore also advantageous to vary this value a depending on ΔQ.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, according to the present invention, it is possible to prevent deterioration of drivability such as breathing and sluggishness during acceleration transitions, and deterioration of NOx emissions, and also to prevent deterioration of HC and Co emissions during deceleration transitions. can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a timing diagram for explaining the intake characteristics of fuel injected from a sub-injector, FIG. 2 is an overall block diagram for explaining the present invention in detail, and FIG. 3 is a fuel injection diagram for an internal combustion engine according to the present invention. FIG. 4 is a detailed circuit diagram of the control circuit 10 in FIG. 2, and FIG.
6 are flowcharts for explaining the operation of the control circuit 10 in FIG. 3, FIG. 7Q, FIG. (Figures 10 to 10 are graphs for explaining N) and values ΔK t N r (N+') r Nl in Figure 7 (B). 1: Engine body, 3-1 to 3 -2: Main fuel injector, 5: Sub-fuel injector, 6: Air flow meter, 8°9: Rotation angle sensor, 10: Control circuit. Patent applicant: Toyota Motor Corporation Patent attorney Akira Aoki Kazuyuki Shinishitate, Patent Attorney Matsushita Souyuki, Patent Attorney Akira Yamaguchi, Patent Attorney Masaya Nishiyama Figure 7 (A) (8) 0 N2' Figure 8 (Small) ΔQ (Many) Figure 9 (Small) 6Q (many) (little) ΔQ (many)

Claims (1)

[Scope of Claims] 1. In addition to the main fuel injection valve provided for each cylinder, an l1lJ fuel injection valve is provided in the upstream portion of the intake passage in common for each of the cylinders, and the fuel injection valve is provided in accordance with predetermined operating state parameters. In an internal combustion engine in which a first fuel injection state by both the main and auxiliary fuel injection valves and a second fuel injection state by only the main fuel injection valve are possible according to the predetermined operating state parameter, a first switching means for switching from the first fuel injection state to the second fuel injection state; a fuel increasing means for increasing the injection amount of the main fuel injection valve during the transition of the switching; and the predetermined operating state.・The above-mentioned second
a second switching means for switching from the fuel injection state to the first fuel injection state, and a fuel reduction means for reducing and correcting the injection amount of the main fuel injection valve during the transition of the switching. 2. A fuel supply control device for an internal combustion engine, characterized in that when the first switching means
switching from the fuel injection state to the second fuel injection state,
The fuel supply control device for an internal combustion engine according to claim 1, wherein the second switching means switches from the second fuel injection state to the first fuel injection state when the engine is not accelerating.