JPH0192547A - Electronically controlled fuel injection device for multi-cylinder internal combustion engine - Google Patents

Abstract

PURPOSE:To aim at enhancing the acceleration performance over the whole operating range by aiming at increasing the acceleration fuel amount by normal fuel injection under sequential control during moderate acceleration operation while aiming at increasing the acceleration fuel amount by normal fuel injection and interrupt injection during abrupt acceleration operation. CONSTITUTION:During normal operation of an engine, a sequential control means C controls fuel injection valves B1 through Bn in accordance with a fuel injection amount which is set by a fuel injection amount setting means A in accordance with an operating condition of the engine. When an acceleration operation condition detecting means D detects a moderate acceleration operation condition, a first acceleration fuel amount setting means E sets a fuel injection amount during normal fuel injection in accordance with the above-mentioned increased fuel amount and the above- mentioned fuel injection amount. Further, when an abrupt acceleration operating condition exceeding a predetermined value is detected, a second acceleration fuel amount setting means F sets a fuel injection amount similar to that by the setting means E, and after fuel injection, an interrupt acceleration fuel injection amount is set so as to control the injection valves B1 through Bn.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electronically controlled fuel injection device of the so-called sequential injection system (hereinafter referred to as sequential control) in which the fuel injection valves of each cylinder are operated individually. In particular, it relates to improving its acceleration performance.

<Prior art> Sequential control described in Japanese Patent Application Laid-Open No. 57-8328 etc. can supply a mixture of fuel and air to each cylinder, and eliminates variations in combustion between cylinders. This has the advantage of eliminating torque fluctuations and reducing torque fluctuations.

Incidentally, in recent electronically controlled fuel injection systems using microcomputers, in those that employ the sequential control described above, the microcomputer controls the fuel injection amount (for example, the rotational speed, intake air flow rate) according to the operating state of the engine (rotational speed, intake air flow rate). For example, in the case of a four-stroke engine, the amount of fuel injected from the fuel injection valve of each cylinder is calculated every two revolutions or every time a reference signal is input from a crank angle sensor.
An injection pulse signal having a pulse width corresponding to the calculated fuel injection amount is output to the fuel injection valve to perform fuel injection (hereinafter referred to as normal fuel injection).

When outputting such an injection pulse signal, the fuel injection start timing or injection end timing is controlled to always be at a constant crank angle position based on a reference signal from a crank angle sensor in synchronization with the intake stroke. There is.

Further, during acceleration operation, the detected intake air flow rate is corrected according to the acceleration operation state, so that the increased fuel injection amount during acceleration is added to the fuel injection amount during normal fuel injection, and the increased fuel injection amount is supplied to the engine. (Patent application 17578/1986)
2 and Japanese Patent Application No. 1981-199135).

Furthermore, during acceleration operation, immediately after the end of the normal fuel injection, the acceleration operation state (for example, the opening change rate of the throttle valve)
An increased fuel injection amount during acceleration is supplied to the engine by interrupt injection according to the acceleration (Japanese Patent Application No. 61-151435, Japanese Patent Application No. 61-199135, Japanese Patent Application No. 61-2079).
No. 74 and Japanese Patent Application No. 148036/1982).

<Problems to be Solved by the Invention> By the way, in the former case where acceleration increase fuel injection amount is added to the fuel injection amount during normal fuel injection to increase acceleration amount, sudden acceleration operation due to rapid throttle valve operation is not possible. Due to the increase in the intake air flow rate during the engine operation, the demand for an increase in the amount of fuel increases compared to when the fuel injection is set.Particularly in the early stages of acceleration operation, the fuel injection amount becomes insufficient and acceleration performance deteriorates.

In addition, in the latter case, when the amount is increased only when the interrupt injection is performed immediately after the end of the normal fuel injection, the amount of CO and HC is increased compared to when the amount is increased at the time of setting during the commonly used slow acceleration operation.
The problem is that the amount of emissions increases. In other words, when the interrupt injection is performed when the end timing of normal fuel injection is set to the point at which the intake valve starts to open (hereinafter referred to as intake top dead center), the interrupt injection occurs at the middle of the intake valve opening period. If this continues until the end of the cycle, cold, un-atomized fuel is sucked in, which worsens engine combustion, greatly increases CO and HC emissions, and deteriorates acceleration performance, further leading to deterioration of fuel efficiency.

The present invention has been made in view of the above circumstances, and provides an electronically controlled fuel injection device for a multi-cylinder internal combustion engine that can maintain optimal acceleration performance under all acceleration driving conditions and reduce CO and HC emissions. The purpose is to provide

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention provides a fuel injection amount setting means A that sets the fuel injection amount according to the engine operating state.
The fuel injection valves B1 to B7 are provided for each cylinder, and by individually operating these fuel injection valves B, to B7, the timing is adjusted to the intake stroke of each cylinder and normal fuel is injected according to the fuel injection amount. sequential control means C for injecting; and an acceleration operation state detection means for detecting an acceleration operation state; a first acceleration fuel amount setting means E that sets a fuel injection amount during normal fuel injection based on the fuel injection amount; a second acceleration fuel amount setting means F that sets a fuel injection amount during normal fuel injection based on the fuel injection amount and the fuel injection amount and also sets an acceleration interrupt injection amount after the injection ends; A driving means G that interrupts the normal fuel injection with a signal corresponding to the interrupt injection amount and outputs the signal to the fuel injection valve B I"' B- to drive the fuel injection valves B, to B7. did.

<Function> In this way, during slow acceleration operation, the acceleration amount is increased during normal fuel injection by sequential control, while during rapid acceleration operation, the acceleration amount is increased during the normal fuel injection, and the acceleration amount is increased by interrupting the normal fuel injection. I tried to figure it out.

<Example> An example of the present invention will be described below based on FIGS. 2 to 4.

In FIG. 2, an electromagnetically driven fuel injection valve 2 is installed in the intake port of each cylinder of an internal combustion engine 1, and a throttle valve 3. Air flow meter4. Air cleaner 5 is installed.

In addition to the intake air flow rate Q signal from the air flow meter 4, the control device 6, which includes a microcomputer, also receives an engine rotation speed N signal detected by the crank angle sensor 7, and an acceleration signal attached to the throttle valve 3. Throttle valve opening α signal from throttle sensor 8 as operating state detection means.

Cooling water temperature (water temperature) signals etc. from the water temperature sensor 9 are input, and based on these signals, a fuel injection signal synchronized with engine rotation is output to the fuel injection valve 2 to periodically perform fuel injection. It looks like this.

Incidentally, the crank angle sensor 7 receives a signal for each unit angle (for example, 1') for detecting the engine speed, a cylinder discrimination signal at a specific crank angle position of a specific cylinder (for example, #1 cylinder), and a predetermined signal for each cylinder. A reference signal (simultaneously with the cylinder discrimination signal for #1 cylinder) is output at the crank angle position.

Here, the control device 6 constitutes sequential control means, fuel injection amount setting means, first and second acceleration fuel amount setting means, and driving means.

Next, the operation will be explained according to the flowcharts of FIGS. 3 and 4.

First, sequential control will be explained. The fuel injection amount TI is calculated according to engine operating conditions such as rotational speed and intake air flow rate. Then, by individually operating the fuel injection valves of each cylinder at a rate of once per two revolutions of the engine according to the ignition order of each cylinder, the fuel injection valves are arranged so that the fuel injection ends at the intake top dead center of each cylinder. A quantity Ti is supplied to each cylinder.

Further, for example, during deceleration operation, when the detected engine speed is equal to or higher than the fuel cut speed, injection control of the fuel injection valve 2 is stopped to perform a fuel cut. Further, when the engine speed decreases to the recovery speed, fuel power is applied to restart injection control of the fuel injection valve 2.

During such sequential control, the routine shown in FIG. 3 is executed every 10 m5ec.

At Sl, various detection signals from the crank angle sensor 7, throttle sensor 8, etc. are read.

In S2, the opening change rate Δα is calculated from the throttle valve openings detected in the previous and current routines.

In S3, the load correction amount KQ is calculated based on the following equation.

KQ, = (T2 at 4/4 load - TP of previous routine)
/ (4/4 load time 'r, -1,5) In S4, Acc is calculated based on the following equation for the increased intake coefficient during acceleration.

K, 5cc= (KΔIX + KN) X K Q
zKΔα is a correction coefficient retrieved from the map based on the opening degree change rate Δα of the throttle valve, and zKΔα is a correction coefficient retrieved from the map based on the engine rotational speed N.

In S5, the basic injection amount T is calculated using the following equation.

TP=K(Q+KoAcc)/NK is a constant, Q is the intake air flow rate detected by the air flow meter 4, and N is the engine rotation speed.

In S6, based on the opening degree change rate Δα calculated in S2, sudden acceleration operation (for example, Δα>1.6°/10m5
It is determined whether or not ec) has been started, and if YES, the process advances to S7, and if NO, the process advances to S19.

In S7, it is determined whether or not it is the first time for an interrupt injection during fuel cut (hereinafter referred to as cut interrupt injection). If YES, the process advances to S9, and if NO, the process advances to S14.

In S9, the cut-time interrupt injection amount TN is used as the acceleration-time interrupt injection amount! After calculating NJ using the following equation, the process proceeds to step 310.

TNINJ=T Δ αx'rTw Here, TΔα is an opening change rate dependent increase coefficient that depends on the opening change rate Δα, and is set to increase as Δα increases. TT.

is a water temperature dependent increase coefficient that depends on the cooling water temperature, and is set to become smaller as the cooling water temperature rises.

At 310, it is determined whether the normal fuel injection in the cylinder immediately before the detection of sudden acceleration operation has ended, and when YES, 31
1, and if No, proceed to 320.

In Sll, the cut interruption injection amount T calculated in S9
An interrupt injection signal corresponding to NINJ is output to the fuel injection valve 2 to perform the first cut interrupt injection after the acceleration operation is detected after the last normal fuel injection is completed.

312, F indicates that it is an interrupt injection immediately after fuel cut.
After storing LAGA=1 in the RAM, the process advances to S13.

In S13, after adding +1 to the number of interrupt injections during cut nTN to set a new number of interrupt injections during cut, nTN,
Proceed to S20.

On the other hand, during a sudden acceleration operation from a time when a fuel cut is not performed, it is determined in S14 whether or not this is the first interrupt injection (hereinafter referred to as normal interrupt injection) from a time when a fuel cut is not performed; When the answer is YES, the process advances to S15, and when the answer is No, the process advances to 320.

In S315, the normal interrupt injection amount TRINJ as the acceleration interrupt injection amount is calculated using the following equation, and then the process proceeds to S16.

TRINJ=TΔαx TPIIX K QzHere,
TΔα and 'rTw are the same as the expression for the cutting injection amount. Also, KQ is (TP at 4/4 load - Tp at acceleration
) / (4/4 TP under load - TP during road running), and the TP during acceleration calculated during acceleration is larger than the TP during road running. This makes KQt smaller than 1. Therefore, the normal interrupt injection amount TRfNJ is smaller than the cut interrupt injection amount TNfNJ by a predetermined amount, and this difference approximately corresponds to the wall flow fuel amount.

In S16, it is determined whether the normal fuel injection in the cylinder immediately before the detection of sudden acceleration operation has ended, and if YES, 317
If the answer is No, the process proceeds to 320.

In S17, the normal interrupt injection amount TR calculated in S15 is
An interrupt injection signal corresponding to INJ is output to the fuel injection valve 2, and the first normal interrupt injection after the acceleration operation is detected is performed in the cylinder after the last normal fuel injection.

51B, after adding +1 to the number of normal interrupt injections n1lN to set a new number of normal interrupt injections nRN, S20
Proceed to.

In S19, FLAGTN is set to O. Therefore, except during sudden acceleration operation after fuel cut, FLAG? ,
is set to 0.

In S20, various correction coefficients C0EF are calculated based on water temperature and the like.

In S21, the fuel injection amount T during normal fuel injection is calculated using the following equation.

T(= 2 TP X COE F + TS and
The calculated fuel injection amount Ti is supplied to the engine during normal fuel injection at a rate of once for every two revolutions of the engine according to the ignition order of each cylinder by sequential control.

In this way, during slow acceleration operation, the acceleration increase fuel injection amount is added to normal fuel injection (at S5, Q is added to Ac
c), an acceleration increase is attempted during normal fuel injection, while an acceleration increase is attempted during normal fuel injection during sudden acceleration operation, and an acceleration increase is also attempted by interrupt injection.

Next, the flowchart of FIG. 4 will be explained. This routine is normally executed at the end of fuel injection (TzEND).

In S31, it is determined from the opening change rate of the throttle valve, etc. whether or not rapid acceleration is currently being performed. If YES, the process advances to S32, and if NO, the process advances to S40.

In S32, it is determined whether the FLAG_N is 1 or not, and Y
When the answer is ES, that is, when the accelerating operation starts from the fuel cut, the process advances to S33, and when the answer is NO, that is, when the accelerating operation starts from when the fuel cut is not performed, the process goes to S36.

In S33, it is determined whether or not the number of interrupt injections during cut nTN is less than or equal to the set number of injections N (for example, three times). If YES, the process proceeds to S34; if NO, the process proceeds to S40.

Step 4 In S34, after outputting the interrupt injection signal corresponding to the cut interrupt injection amount T, NJ calculated in S9 to the fuel injection valve 2, in step 335, the cut interrupt injection number nTN is increased.
1 is added to set a new number of cut interruption injections nTN, and the routine ends.

In this way, the cut-time interrupt injection amount T is immediately after the end of normal fuel injection from the fuel injection valve 2 of each cylinder according to the ignition order
N I N J is supplied to the engine.

On the other hand, during acceleration operation when fuel cut is not performed, it is determined in S36 whether the number of normal interrupt injections nRN is less than or equal to the set number of injections N, and if YES, the process advances to 337, and if NO, the process advances to 340.

In S37, the normal interrupt injection amount TRINJ is calculated based on the most recently obtained basic injection amount TP using the formula in S15 (here, the basic injection amount Tp is used to calculate KQ2).

33B, the normal interrupt injection amount TR calculated in S37
After outputting the interrupt injection signal corresponding to INJ to the fuel injection valve 2, +1 is added to the normal interrupt injection number n- to set a new normal interrupt injection number nRN in S39, and the routine is ended.

In this way, the normal interrupt injection amount TRI is set immediately after the normal fuel injection from the fuel injection valve 2 of each cylinder is completed according to the ignition order.
NJ is supplied to the engine.

In step 340, after setting FLAGTN to O, in step S41, the number of interrupt injections nTN during cut and the number n of normal interrupt injections are set.
RN to its initial value (for example, O).

As explained above, during fuel cut or during sudden acceleration operation immediately after, the cut interrupt injection amount to which fuel corresponding to approximately the wall flow fuel amount is added is supplied to the engine immediately after the end of normal fuel injection. This makes it possible to suppress lean air-fuel ratio during acceleration operation immediately after fuel cut. Therefore, it is possible to suppress NOX emissions and also to suppress vehicle vibration during re-acceleration operation.

Furthermore, during slow acceleration operation, since the acceleration amount is increased during normal fuel injection, fuel is supplied to the engine immediately before the intake valve opens, so that deterioration of engine combustion can be prevented. This makes it possible to reduce CO and HC emissions, prevent deterioration of fuel efficiency, and further improve acceleration performance. Further, since the acceleration amount is increased by the normal fuel injection and the interrupt injection during sudden acceleration operation, the acceleration amount can be increased by responsively following a sudden increase in the intake air flow rate, so that acceleration performance can be improved.

<Effects of the Invention> As explained above, the present invention aims to increase the acceleration amount by normal fuel injection under sequential control during slow acceleration operation, while aiming to increase the acceleration amount by normal fuel injection and interrupt injection during sudden acceleration operation. Therefore, it is possible to improve acceleration performance in all driving ranges and to reduce CO and HC emissions.

[Brief explanation of the drawing]

FIG. 1 is a diagram corresponding to claims of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIGS. 3 and 4 are flowcharts of the same.

Claims (1)

[Claims] A fuel injection amount setting means that sets the fuel injection amount according to the engine operating state, a fuel injection valve provided for each cylinder, and individual operation of these fuel injection valves control the intake stroke and timing of each cylinder. In an electronically controlled fuel injection device for a multi-cylinder internal combustion engine, the electronically controlled fuel injection device for a multi-cylinder internal combustion engine includes: sequential control means for performing normal fuel injection according to the fuel injection amount; a first acceleration fuel amount setting means for setting a fuel injection amount during normal fuel injection based on an acceleration increase fuel injection amount and the fuel injection amount when a slow acceleration driving state is detected; When a sudden acceleration driving condition exceeding
a second acceleration fuel amount setting means for setting a fuel injection amount during normal fuel injection based on the acceleration increase fuel injection amount and the fuel injection amount and setting an acceleration interrupt injection amount after the injection ends; a driving means for interrupting the normal fuel injection with a signal corresponding to the interruption injection amount during acceleration and outputting the signal to the fuel injection valve to drive the fuel injection valve. The engine's electronically controlled fuel injection system.