JPH01208544A - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent the fluctuation in fuel injecting quantity at the time of decelerat ing operation by providing a means of prohibiting the increase of weighting with respect to the latest detected value which is carried out for ensuring the following property to the change in an intake air quantity at the time of judging to be a deceler ating operating condition and in an intake air quantity flat operation zone. CONSTITUTION:A judging means A judges the accelerating/decelerating operating condition of an engine based on the change in opening of a throttle valve. A weighted- average operating means C carries out a weighted-average operation between the latest detected value of an intake air flow rate and the value of the past intake air flow rate and outputs this weighted-average value to a fuel injection quantity setting means B as an intake air flow rate signal. At the time of accelerating/decelerating an engine, the weighting of the latest detected value is increased more than normally by a weighting variable means D. On the other hand, when a judging means E judged to be an operating zone in which an intake air quantity is not varied irrespective of the change in opening of a throttle valve while being judged to be the decelerating operation of an engine, the increase of weighting is prohibited by a weighting change prohibiting means F.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and more particularly to a technique for smoothing pulsations in a detected intake air flow rate.

(Prior art) Conventionally, in an internal combustion engine equipped with an electronically controlled fuel injection device, the fuel injection amount has been set as follows (1983).
-Refer to Publication No. 183440, etc.).

That is, the basic fuel injection amount 'rp (-
KXQ/NS K is a constant) is calculated, and this Tp is calculated based on the air-fuel ratio feedback, which is set mainly based on various correction coefficients C0EF depending on the cooling water temperature and the air-fuel ratio detected by an oxygen sensor installed in the exhaust system. Correction coefficient LAMB
A correction calculation is performed using DA and a correction numerator s based on battery voltage to determine the final fuel injection amount Ti.

For example, in a single point injection (hereinafter referred to as SPI) system, an injection signal (valve opening drive signal) having a pulse width corresponding to the fuel injection amount Ti is output to the electromagnetic fuel injection valve every % rotation of the engine. Then, fuel is injected and supplied to the engine on and off.

By the way, when the engine is operating under high load, intake pulsation occurs, so if the detected value of the intake air flow rate is used as is to set the fuel injection amount, surging will occur due to torque fluctuations that accompany fluctuations in the fuel injection amount. Therefore, conventionally, the occurrence of surging is suppressed by taking a weighted average of the latest detected value of the intake air flow rate and past data, and setting the fuel injection amount using the smoothed value. That's what I do.

In addition, in the smoothing process using the weighted average, if a weighted average is performed in which past intake air flow rate data is weighted more heavily in order to effectively suppress intake pulsation during steady state, acceleration/deceleration driving conditions (transient When a transient operating state of the engine is detected based on a change in the opening of the throttle valve installed in the intake system, the weighted average calculation is performed as follows: The latest detected values are weighted more heavily than the steady state of operation (see Japanese Patent Application No. 61-305349, etc.).

<Problem to be solved by the invention> However, in reality, there is an operating region (hereinafter simply referred to as the Q-flat operating region) in which the intake air flow rate does not change even if the throttle valve opening changes, and the throttle valve opening changes. Even if the deceleration operating state of the engine is detected based on the engine deceleration, in the initial stage of deceleration, the intake air flow rate may remain unchanged in the Q flat operating region as shown in FIG. When a transient operating state is detected due to a change in opening, the latest detected value is unconditionally given more weight, so that the intake pulsation in the Q-flat operating region at the beginning of deceleration can be smoothly smoothed out. Therefore, there was a risk that fluctuations in the fuel injection amount (basic fuel injection amount Tp) would occur.

The present invention has been made in view of the above problem, and even when the deceleration operating state of the engine is detected based on the change in the throttle valve opening, when the engine is in the Q flat operating region, the intake pulsation does not occur. The purpose is to avoid fluctuations in the injection amount at the initial stage of deceleration and improve driveability by suppressing the injection amount well. <Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. , a fuel injection amount setting means for setting the fuel injection amount based on the engine operating state including the detected engine rotational speed and intake air flow rate; and injecting the amount of fuel set by the fuel injection amount setting means into the engine. In an electronically controlled fuel injection device for an internal combustion engine, the electronically controlled fuel injection device for an internal combustion engine is equipped with: a fuel injection means for supplying fuel; calculating a weighted average of the latest intake air flow rate detected by the intake air flow rate detection means and the past intake air flow rate value; weighted average calculation means for outputting this weighted average value as an intake air flow rate signal to the fuel injection amount setting means; a weighting variable means that increases the weighting of the latest detected value in the weighted average more than usual; and an intake air intake that determines an intake air amount flat operating region that is an operating region in which the intake air flow rate does not change even if the opening degree of the throttle valve changes. When the deceleration operating state of the engine is determined by the amount flat operating region determining means and the acceleration/decelerating operating state determining means, and the intake air amount flat operating region determining means determines that the engine is in the intake air amount flat operating region. and a variable weighting prohibition means for prohibiting the weighting variable means from increasing the weighting of the latest detection value.

(Operation) In this configuration, the fuel injection amount setting means sets the fuel injection amount based on the engine operating state including the engine rotation speed and intake air flow rate detected by the engine rotation speed detection means and the intake air flow rate detection means. .

The fuel injection means injects and supplies the amount of fuel set by the fuel injection amount setting means to the engine.

On the other hand, the weighted average calculating means weights and averages the latest detected value of the intake air flow rate detected by the intake air flow rate detection means and the past value of the intake air flow rate, smoothes the detected value, and calculates the weighted average value. is output to the fuel injection amount setting means as an intake air flow rate signal. Here, when the acceleration/deceleration operating state of the engine is detected by the acceleration/deceleration operating state determination means based on the change in the throttle valve opening, the weighting variable means changes the weighting of the latest detected value in the weighted average by the weighted average calculating means to the normal value. to ensure followability in transient operating conditions.

However, even when the deceleration operating state of the engine is determined by the acceleration/deceleration operating state discriminating means, when the intake air amount flat operating region discriminating means determines that the intake air amount flat operating region is present, the above-mentioned Since the weighting variable prohibiting means prohibits the weighting variable means from increasing the weighting of the latest detected value, in the intake air amount flat operation region, normal weighting corresponding to the steady operating state is performed to improve the intake pulsation. Deter.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 2 showing the configuration of one embodiment, an intake manifold 2 of an engine 1 includes a throttle valve 3 disposed upstream from a branch portion to control the intake air flow rate in conjunction with an accelerator pedal.
An air flow meter 4 as an intake air flow rate detection means for detecting the intake air flow rate Q and a fuel injection valve 5 as a fuel injection means are provided on the upstream side thereof.The fuel injection valve 5 is controlled by a control unit 6 containing a microcomputer. The valve is driven to open by an injection pulse signal, and fuel, which is pressure-fed from a fuel pump (not shown) and adjusted to a predetermined pressure, is injected into the intake manifold 2.

Further, a water temperature sensor 7 is provided to detect the cooling ice storage in the cooling jacket of the engine 1, and an oxygen sensor 9 is provided to detect the oxygen concentration in the exhaust gas in the exhaust passage 8. Further, the distributor (not shown) has a built-in crank angle sensor 10 that also serves as engine rotation speed detection means, and counts unit crank angle signals outputted from the crank angle sensor 10 in synchronization with engine rotation for a certain period of time. Alternatively, the engine rotation speed N is detected by measuring the period of the reference crank angle signal.

Further, the shaft of the throttle valve 3 has a throttle valve opening T.
A throttle sensor 11 is provided to detect VO, and is turned on when the throttle valve 3 is in the fully closed position (idle position).
An idle switch 12 is provided, and a neutral switch 13 is further provided that is turned on when the transmission is in a neutral state. The throttle sensor 11 together with the control unit 6 constitutes acceleration/deceleration operation state determining means, and in this embodiment, as will be described later, the Q flat operation region is defined as the throttle valve opening TvO.
The throttle sensor 11 is connected to the crank angle sensor 10 in order to make the determination based on the engine rotational speed N.
□ Together, they constitute an intake air amount flat operation region determination means.

Next, the details of the basic fuel injection amount setting control including the smoothing process of the intake air flow rate detection value will be explained according to the routine shown in the flowcharts of FIGS. 3 and 4. In this embodiment, the functions of the fuel injection amount setting means, the weighted average calculation means 1, the weighting variable means 9, and the weighting variable inhibiting means are configured by software as shown in the above flowchart.

The basic fuel injection amount setting routine shown in the flowchart of FIG. 3 is executed every A rotation of the engine 1 based on a signal from the crank angle sensor 10.

In step (denoted as "S" in the figure, the same applies hereinafter) l, the integrated value Q su of the intake air flow rate QA detected by the air flow meter 4 while the engine 1 rotates by %
By dividing M by the number of samples I, the simple average value Q of the intake air flow rate QA while the engine 1 rotates by %
s r m□ (←Q,.

/I).

The integrated value Qsum and the number of samples I are set by an integrated value setting routine shown in the flowchart of FIG. Note that this routine is executed every 1 ms.

Here, in step 31, the output voltage Us of the air flow meter 4 is AD converted, and in the next step 32, data on the intake air flow rate QA, which is stored in a map in advance in correspondence with the output voltage Us, is selected. The data on the intake air flow rate QA corresponding to the output voltage Us obtained by AD conversion is searched and obtained.

Then, in step 33, the intake air flow rate QA obtained by searching in step 32 is added to the previous integrated value Qsux, and in the next step 34, each time the detected value QA of the air flow meter 4 is integrated in step 33. The value of the counter I is incremented by 1 to count the number of samples of the integrated value Q3ux.

The integrated value Qsu14 and the number of samples 1 thus obtained are used in step 1 to calculate the simple average value Qs+MpL of the intake air flow rate QA (detected value of the air flow meter 4) while the engine 1 rotates by %. It will be done.

In the next step 2, the integrated value Qsum and the number of samples ■ are reset to zero in order to newly set the integrated value Q3□ and the number of samples ■ in the routine shown in the flowchart of FIG.

In step 3, in order to set the weighting in the weighted average processing described later, the intake air flow rate QA currently detected by the air flow meter 4 is divided by the engine rotation speed N (QA/N) to obtain a value representing the engine load. demand. Here, the simple average value Qs+□ of the intake air flow rate QA during each rotation of the engine l calculated in step 1 may be divided by the engine rotation speed N, and the basic fuel injection amount Tp
The current engine speed N and intake air flow rate QA or simple average value Qs are added to the calculation formula (TP=KXQ/N: is a constant).
+□ may be substituted and this basic fuel injection amount Tp may be used for setting the weighting.

In step 4, it is determined whether the current engine operating state is an idling operating state. Specifically, the idle switch 12 is ON and the neutral switch 13 is OFF.
When it is N, it is determined that the engine is in an idling operating state.

If it is determined in step 4 that the engine is not in an idling state, the process proceeds to step 5 and the throttle sensor 11
Rate of change ΔTVO of throttle valve opening TVO detected at
Determine whether or not engine l is in a decelerating operating state based on 0. Whether or not engine 1 is in a decelerating operating state is determined when the rate of change ΔTVO is, for example, -1,6'/30+as or less. The system is designed so that it is determined that the vehicle is in a deceleration driving state.

Here, if it is determined that the engine 1 is in the deceleration operating state, the process proceeds to step 6 and the current operating state is Q franc).
As shown in Figure 5, it is possible to determine whether or not the current throttle valve opening TVO and engine rotational speed are included in the W range (the operating range in which the intake air flow rate QA does not change even if the throttle valve opening TVO changes). If it is not included in the Q flat region, the process proceeds to step 11;
If it is determined that the engine 1 is in the flat region, the process proceeds to step 7 in the same way as when it was determined in step 5 that the engine 1 is not in the deceleration operating state.

In step 7, similarly to step 5, it is determined whether the engine 1 is in an accelerating operating state based on the throttle valve opening change rate ΔTVO. Here, for example, the rate of change A
When the TVO is 1.6°/100+ms or more, it is determined that the accelerating driving state is in progress. Incidentally, when the process advances from step 6 to step 7, it is of course determined that the engine 1 is not in an accelerating operation state.

If it is determined in step 7 that the engine 1 is in an accelerating operating state, the process proceeds to step 8, where the intake air flow rate QA is
The weighting constant Xll! in the weighted average calculation formula when calculating the weighted average of the simple average value Q3□, V (more weight is given to past values when this weighting constant X□9 is large) is searched and determined based on QA/N calculated in step 3.

That is, as shown in the graph in the flowchart of FIG. 3, the current QA/N (value calculated in step 3) is calculated from among the data of the weighting constant XIIEv, which is stored in the map in advance according to the QA/N. It is calculated by searching for the weighting constant X□9 corresponding to the past weighted average value QAv□9. It is designed to increase the weight.

On the other hand, if it is determined in step 7 that the engine 1 is not in an accelerating operation state, the process proceeds to step 9, and similarly to step 8, the weighting constant X□9 is searched and determined based on QA/H. However, the weighting constant This is to effectively suppress intake pulsation in the state of acceleration, and to ensure responsiveness (followability) to the intake air flow rate in the accelerated driving state.

Then, in step 8 or step 9, the weighting constant
ll! Once V is set, in the next step 10, the simple average value Qs of the intake air flow rate QA calculated in step 1 is calculated.
IMPL and the weighted average value Q calculated in the previous step 10
A weighted average calculation is performed using Av□9 according to the following formula.

On the other hand, when it is determined in step 4 that the engine 1 is in the idling operating state, and when it is determined in step 6 that the engine 1 is not in the Q flat region (in the deceleration operating state and not in the Q flat region), the process advances to step 11, and the weighting Set the constant X□V to zero, and set the simple average values Q3I, 4PL calculated in step 1 this time to the current weighted average value QAv□9
, and the weighted average calculation in step 10 is not performed.

Here, even if it is determined in step 5 that the engine l is in a deceleration operating state, if it is determined in the next step 6 that it is included in the Q flat region, the process will proceed from the next step 7 to step 9. , is searched from the map of the weighting constant (Step 9) This makes it possible to satisfactorily smooth out the intake pulsation in the Q flat region at the beginning of deceleration.

In other words, even if the engine 1 is determined to be in a deceleration operating state and is an operating state in which followability of the intake air flow rate should be ensured, followability is ensured when it is in the Q flat region. Prohibits the increase in weighting (decrease in weighting constant X□, or avoid weighted average processing when proceeding to step 11) for the latest detected value (current simple average value Q s +□L), which is performed for the purpose of The intake pulsation is smoothly smoothed so that fluctuations in the basic fuel injection amount Tp do not occur.In addition, when the operation is decelerating and is not in the Q flat operation region, step 11 is performed.
By proceeding to step 1, weighted average calculation is not performed, and followability to changes in the intake air flow rate is ensured.

□When the calculation and setting of the weighted average value Qav□9 is completed as described above, in the next step 12, it is determined whether the engine 1 is in a rapid acceleration operation state or not by the throttle valve opening change rate Δ.
Judgment is made based on TVO. Here, for example, when the throttle valve opening change rate ΔTVO is 1.6°/30m5 or more, it is determined that the engine 1 is in a rapid acceleration operation state, and when a sudden acceleration determination is made, the process proceeds to step 13.

In step 13, it is determined whether or not the sudden acceleration determination in step 12 is the first time, and when it is determined that it is the first time, the process proceeds to step 14 and the flag is set to 1, but if it is not the first time, step 14 is executed. Jump to step 15
Proceed to.

In step 15, a correction amount Δ is used to correct the detection delay of the air flow meter 4 during the rapid acceleration operation state of the engine 1.
Q is calculated according to the following formula.

ΔQ←(QAv*tv-previous QAv*iv) KMANI, that is, the currently calculated or set weighted average value QAv□9
The correction amount ΔQ is obtained by subtracting the previous weighted average value QAv□9 from the coefficient and multiplying it by 4AN1. Note that the coefficient □1 is determined depending on the collector volume of the intake manifold 2 and the responsiveness of the air flow meter 4, and is set to a value of about 2.6, for example.

In the next step 16, it is determined whether the correction amount ΔQ calculated in step 15 is a value exceeding zero, and the correction amount ΔQ is determined.
When Q>O, the process proceeds to step 17 to determine the flag, and only when the correction amount ΔQ>O and the flag is 1, the process proceeds to step 18 to perform an increase correction of the intake air flow ff1Q. On the other hand, if it is determined in step 16 that the correction amount ΔQ≦0, the flag is set to zero in step 19, and then the process proceeds to step 20.

In step 18, the final intake air flow rate Q (final Q) is set by adding the correction amount ΔQ to the weighted average value Qav□9 calculated in step IO this time to increase the amount. The weighted average value QAVIIEV calculated in step 10 this time is set as the final Q, and no increase correction is performed.

That is, in this embodiment, since the air flow meter 4 and the fuel injection valve 5 are provided upstream of the branch part of the intake manifold 2, the volume of the intake passage downstream of the fuel injection valve 5 is filled during sudden acceleration. However, since there is a delay in detecting the intake air flow rate Q which cannot be used for setting the fuel injection amount of the air flow meter 4, the correction amount ΔQ calculated in step 15 is used. However, even when the intake air flow rate Q has stabilized after rapid acceleration, if the increase correction is performed using the correction amount ΔQ, it will result in promoting intake pulsation, so this is not done in this embodiment. In order to solve this problem, once the weighted average value QAVREv shows a decreasing tendency, the increase correction is not performed until there is a new sudden acceleration.

When the engine 1 is accelerated and it is determined for the first time in step 13, the flag is set to 1, and the flag is set to 1 until the weighted average value QAv□9 shows a decreasing tendency (it is determined that the correction amount ΔQ≦0 in step 16). ), an increase correction is performed in step 18, but when the weighted average values QAv, lEv start to show a decreasing tendency, the flag is set to zero in step 19. Even if the rapid acceleration state of engine 1 is determined,
Since the final Q is set in step 20, the increase correction is not performed, and this prohibition state of increase correction continues until the initial determination of the sudden acceleration driving state is made again and the flag is set to 1.

Note that when the final Q is set in step 18 or step 20, the final Q is used in the next step 21 to calculate the basic fuel injection amount Tp (← × final Q/N; is a constant)
is calculated. Although omitted in this embodiment, in a separate routine, a correction numerator s based on the battery voltage, an air-fuel ratio feedback correction coefficient LAMBDA based on the air-fuel ratio detected by the oxygen sensor 9, a cooling water temperature detected by the water temperature sensor 7, etc. Various correction coefficients C0 based on
The basic fuel injection amount Tp is corrected by EF or the like to set the final fuel injection amount Ti, and an injection pulse signal corresponding to this fuel injection amount Ti is output to the fuel injection valve 5 in synchronization with the engine rotation. Then, fuel is injected and supplied to the engine 1 on and off.

<Effects of the Invention> As explained above, according to the present invention, when the engine is in a decelerating operating state and it is determined that the engine is in the Q flat operating region, even if the engine is in an accelerating/decelerating operating state, the intake air is Since increasing the weighting of the latest detected value, which is done to ensure followability to flow rate changes, is prohibited, intake pulsations in the Q-flat BiM region at the beginning of deceleration operation are smoothed out, and fluctuations in fuel injection amount are reduced. Since this can be prevented, there is an effect that drivability during deceleration driving can be improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a system diagram showing an embodiment of the invention, Figs. 3 and 4 are flowcharts showing the control contents of the above embodiment, and Fig. 5 is a Q
The graph showing the flat area and FIG. 6 are time charts for explaining the problems of the conventional technology. 1... Engine 2... Intake manifold 3...
Throttle valve 4... Air flow meter 5...
・Fuel injection valve 6...Control unit 1
0... Crank angle sensor 1 ■... Throttle sensor Patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio Sasashima Figure 1 Figure 4

Claims (1)

[Scope of Claims] An engine rotation speed detection means for detecting the engine rotation speed, an intake air flow rate detection means for detecting the intake air flow rate of the engine, and an engine operating state including the detected engine rotation speed and intake air flow rate. An electronically controlled fuel injection device for an internal combustion engine, comprising: a fuel injection amount setting means for setting a fuel injection amount based on the fuel injection amount setting means; and a fuel injection means for injecting and supplying the amount of fuel set by the fuel injection amount setting means to the engine. , an acceleration/deceleration operating state determination means for detecting the opening of a throttle valve installed in an intake system of the engine and determining the acceleration/deceleration operating state of the engine based on a change in the opening of the throttle valve; A weighted average of the latest detection value of the intake air flow rate detected by the air flow rate detection means and a past value of the intake air flow rate, and the weighted average value is outputted to the fuel injection amount setting means as an intake air flow rate signal. an average calculating means; and a weighting variable means for increasing the weighting of the latest detected value in the weighted average by the weighted average calculating means when the acceleration/deceleration driving state of the engine is determined by the acceleration/deceleration driving state determining means. , intake air amount flat operating region determining means for determining an intake air amount flat operating region, which is an operating region in which the intake air flow rate does not change even if the opening degree of the throttle valve changes; and engine deceleration by the acceleration/deceleration operating state determining means. Variable weighting that prohibits the variable weighting means from increasing the weighting on the latest detected value when the operating state is determined and the flat intake air amount operating region determining means determines that the intake air amount flat operating region is present. An electronically controlled fuel injection device for an internal combustion engine, characterized in that it is provided with a prohibition means.