JPH0768926B2 - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and more particularly to a technique for smoothing a pulsation of 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 is set as follows (actual development 61-
See 183440, etc.).

That is, from the intake air flow rate Q detected by the air flow meter and the engine rotation speed N, the basic fuel injection amount Tp (= K × Q /
N; K is a constant), and this Tp is set based on various correction factors COEF mainly based on the cooling water temperature and the air-fuel ratio detected by the oxygen sensor installed in the exhaust system. The final fuel injection amount Ti is determined by performing a correction calculation using the correction coefficient LAMBDA and the correction amount Ts based on the battery voltage.

Then, 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 given to the electromagnetic fuel injection valve every 1/2 revolution of the engine. Is output, and fuel is injected and supplied to the engine on / off.

By the way, during engine high load operation, intake pulsation occurs, so if the fuel injection amount is set using the detected intake air flow rate as is, surging will occur due to torque fluctuations associated with fluctuations in the fuel injection amount. Therefore, conventionally, the latest detection value of the intake air flow rate and the past data are weighted averaged, and the fuel injection amount is set using the value smoothed by this, thereby suppressing the occurrence of the surging. I am trying.

Further, in the smoothing processing by the weighted average, if the weighted average with a larger weight is applied to the past intake air flow rate data so that the intake pulsation in the steady state can be effectively suppressed, the acceleration / deceleration operation state (transient When the transient operating state of the engine is detected based on the change in the opening of the throttle valve installed in the intake system, the weighting in the weighted average calculation is performed. The latest detected value is weighted more than in the steady operation state (see Japanese Patent Application No. 61-305349, etc.).

<Problems to be Solved by the Invention> However, in reality, there is an operating region in which the intake air flow rate does not change even when the opening of the throttle valve changes (hereinafter simply referred to as Q-flat operating region), and it is based on the throttle valve opening. Even if the deceleration operation state of the engine is detected by the engine, the intake air flow rate may not change in the Q flat operation region as shown in FIG. 6 in the initial stage of deceleration.
When a transient operating state is detected by a change in the throttle valve opening, the latest detected value is unconditionally weighted. Therefore, the intake pulsation in the Q-flat operating region at the initial stage of deceleration is smoothly smoothed. However, the fuel injection amount (basic fuel injection amount Tp) may fluctuate.

The present invention has been made in view of the above problems. Even when the deceleration operation state of the engine is detected based on the change in the throttle valve opening, the intake pulsation is generated in the Q flat operation region. An object of the present invention is to prevent the fluctuation of the injection amount in the initial stage of deceleration and improve the drivability by performing the excellent suppression.

<Means for Solving the Problem> Therefore, in the present invention, as shown in FIG. 1, an engine rotational speed detecting means for detecting an engine rotational speed, an intake air flow rate detecting means for detecting an intake air flow rate of the engine, Fuel injection amount setting means for setting the fuel injection amount based on the engine operating state including the detected engine speed and intake air flow rate, and the amount of fuel set by the fuel injection amount setting means is injected and supplied to the engine. In an electronically controlled fuel injection device for an internal combustion engine including fuel injection means, the opening degree of a throttle valve envisaged in the intake system of the engine is detected, and the engine addition based on the change in the opening degree of the throttle valve is detected. Acceleration / deceleration operation state determination means for determining the deceleration operation state, the latest detection value of the intake air flow rate detected by the intake air flow rate detection means and the past intake air flow rate value are weighted averaged, and this weighted average is calculated. value Is output to the fuel injection amount setting means as an intake air flow rate signal, and the latest weighted average by the weighted average calculation means when the acceleration / deceleration operation state of the engine is determined by the acceleration / deceleration operation state determination means. A weighting variable means for increasing the weighting of the detection value of the intake air amount, and an intake air amount flat operating region for determining an intake air amount flat operating region in which the intake air flow rate does not change even if the opening of the throttle valve changes. The weighting variable when the deceleration operation state of the engine is determined by the determination means and the acceleration / deceleration operation state determination means, and the intake amount flat operation area is determined by the intake amount flat operation area determination means. A variable weight prohibiting means for prohibiting an increase in weighting for the latest detected value by means is provided.

<Operation> In such a configuration, the fuel injection amount setting means sets the fuel injection amount based on the engine operating state including the engine rotation speed and the intake air flow rate detected by the engine rotation speed detection means and the intake air flow rate detection means. . And the fuel injection means is
The amount of fuel set by the fuel injection amount setting means is injected and supplied to the engine.

On the other hand, the weighted average calculation means smooths the detection values by weighting the latest detected value of the intake air flow rate detected by the intake air flow rate detection means and the value of the past intake air flow rate, and 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 determination means detects the acceleration / deceleration operating state of the engine based on the change in the throttle valve opening, the weighting variable means normally weights the latest detected value in the weighted average by the weighted average calculation means. To ensure followability in transient operating conditions.

However, even when the deceleration operation state of the engine is determined by the acceleration / deceleration operation state determination means, when it is determined by the intake amount flat operation area determination means that it is in the intake amount flat operation area, Since an increase in weighting for the latest detected value by the weighting variable means is prohibited by the weighting variable prohibiting means, normal weighting corresponding to the steady operation state is performed in the intake air amount flat operating region to favorably suppress the air pulsation. .

<Examples> Examples of the present invention will be described below with reference to the drawings.

Referring to FIG. 2 showing the structure of one embodiment, an intake manifold 2 of an engine 1 has a throttle valve 3 upstream of a branch portion for controlling an intake air flow rate in cooperation with an accelerator pedal.
And an air flow meter 4 as an intake air flow rate detecting 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 of the control unit 6 including a microcomputer. The valve is driven to open by the injection pulse signal of, and fuel supplied under pressure from a fuel pump (not shown) and adjusted to a predetermined pressure is injected and supplied into the intake manifold 2.

Further, a water temperature sensor 7 that detects the temperature of the cooling water in the cooling jacket of the engine 1 is provided, and an oxygen sensor 9 that detects the oxygen concentration in the exhaust gas of the exhaust passage 8 is provided.
Further, the distributor (not shown) has a built-in crank angle sensor 10 that also serves as engine rotation speed detection means, and counts a unit crank angle signal output 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 cycle of the reference crank angle signal.

Further, the axis of the throttle valve 3 has a throttle valve opening TV
A throttle sensor 11 for detecting O is provided, and
An idle switch 12 that is turned on at the fully closed position (idle position) of the throttle valve 3 is provided, and a neutral switch 13 that is turned on when the transmission is in a neutral state is provided. While the throttle sensor 11 constitutes the acceleration / deceleration operation state determination means together with the control unit 6, in the present embodiment, as will be described later, the Q flat operation area is set in the throttle valve opening TVO and the engine rotation speed N.
Therefore, the throttle sensor 11 and the crank angle sensor 10 constitute an intake air amount flat operation region determining means.

Next, the contents of the basic fuel injection amount setting control including the smoothing process of the intake air flow rate detection value will be described according to the routines shown in the flowcharts of FIGS. 3 and 4. In this embodiment, the functions of the fuel injection amount setting means, the weighted average calculating means, the weighting varying means, and the weighting variation inhibiting means are configured by software as shown in the above flow chart.

The basic fuel injection amount setting routine shown in the flowchart of FIG. 3 is executed every 1/2 rotation of the engine 1 based on the signal from the crank angle sensor 10.

In step (denoted as "S" in the figure, the same applies hereinafter) 1, the integrated value Q _SUM of the intake air flow rate QA detected by the air flow meter 4 while the engine 1 is rotating 1/2 is used as the sample number I. By dividing by
Simple average value of intake air flow rate QA during rotation Q _SIMPL
Calculate (← Q _SUM / I).

The integrated value Q _SUM and the sample number I are set by the 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, the output voltage Us is previously converted.
Intake air flow rate QA stored in the map corresponding to Us
Output voltage obtained by AD conversion in step 31 from the data of
Search for and obtain the intake air flow rate QA data corresponding to Us.

Then, in step 33, the intake air flow rate QA obtained by searching in step 32 is added to the accumulated value Q _SUM so far, and in the next step 34, the detected value of the air flow meter 4 in step 33.
Every time QA is integrated, the value of the counter I is incremented by 1 and the number I of samples of the integrated value Q _SUM is counted.

The integrated value Q _SUM and the number of samples I thus obtained are used in the above step I, and the intake air flow rate QA (detection value of the air flow meter 4) while the engine 1 is rotating 1/2
The simple average value of Q _SIMPL is calculated.

In the next step 2, the integrated value Q _SUM and the sample number I are reset to zero in order to newly set the integrated value Q _SUM and the sample number I in the routine shown in the flowchart of FIG.

In step 3, in order to set the weighting in the weighted averaging process described later, the intake air flow rate QA currently detected by the air flow meter 4 is divided by the engine speed N (QA / N) to obtain a value representing the engine load. Ask. In addition, here
The simple average value Q _SIMPL of the intake air flow rate QA during the half rotation of the engine 1 calculated in step 1 may be divided by the engine rotation speed N, and the calculation formula (Tp of the basic fuel injection amount Tp
= K × Q / N; K is a constant), the current engine speed N and the intake air flow rate QA or the simple average value Q _SIMPL are substituted, and the basic fuel injection amount Tp is used for setting the weighting. good.

In step 4, it is determined whether the current engine operating state is the idle operating state. Specifically, when the idle switch 12 is ON and the neutral switch 13 is ON, it is determined that the engine is in the idle operation state.

When it is determined in step 4 that the engine is not in the idling operation state, the process proceeds to step 5 and whether the engine 1 is in the deceleration operation state based on the change rate ΔTVO of the throttle valve opening TVO detected by the throttle sensor 11. To judge. Whether or not the engine 1 is in the decelerating operation state is determined to be in the decelerating operation state when the rate of change ΔTVO is, for example, −1.6 ° / 30 ms or less.

Here, when it is determined that the engine 1 is in the decelerating operation state, the routine proceeds to step 6, where the current operating state is the Q flat region (even if the throttle valve opening TVO changes, the intake air flow rate Q
Whether or not A is included in the unchanged operating range) is determined based on the current throttle valve opening TVO and the engine speed N as shown in FIG. 5, and when it is not included in the Q flat range. On the other hand, if it is determined that the engine 1 is not in the decelerating operation state at step 5, if it is determined that it is included in the Q flat region, then the procedure proceeds to step 7.

In step 7, as in step 5, it is determined based on the throttle valve opening change rate ΔTVO whether the engine 1 is in the accelerating operation state. Here, for example, the change rate ΔTV
When O is 1.6 ° / 100ms or more, it should be judged that it is in the acceleration operation state. In addition, step 6 to step 7
When it goes to, it goes without saying that it is judged that the engine 1 is not in the acceleration operation state.

Then, when it is determined in step 7 that the engine 1 is in the acceleration operation state, the process proceeds to step 8 and the weighting constant in the weighted average calculation formula when _{performing the} weighted average calculation of the simple average value Q _SIMPL of the intake air flow rate QA. X _REV (the past value is weighted more when this weighting constant X _REV is large) is searched for based on the QA / N calculated in step 3.

That is, as shown in the graph in the flowchart of FIG. 3, the current QA / N (calculated value in step 3) is selected from the data of the weighting constant X _REV stored in the map in advance according to the QA / N. ) Is obtained by searching for the weighting constant X _REV , and X _REV is set larger as the engine 1 with a higher QA / N _operates under higher load, and the weighting with respect to the past weighted average value Q _AVREV is It's getting bigger.

On the other hand, if it is determined in step 7 that the engine 1 is not in the acceleration operation state, the process proceeds to step 9 to search for the weighting constant X _REV based on QA / N as in step 8. However, the weighting constant X _REV searched in step 9 when the engine 1 is not in the accelerating operation state is larger than that in the accelerating operation state.
It is set to a larger value than QA / N, which effectively suppresses intake pulsation in steady operation state and ensures responsiveness (followability) to intake air flow rate in accelerated operation state. is there.

Then, in step 8 or step 9, the weighting constant X
_{When REV} is set, in the next step 10, using the simple average value Q _SIMPL of the intake air flow rate QA calculated in step 1 this time and the weighted average value Q _AVREV calculated in step 10 last time, the weight is calculated according to the following equation. Performs averaging.

On the other hand, when it is determined in step 4 that the engine 1 is in the idle operation state and when it is determined in step 6 that the engine 1 is not in the Q flat region (in the decelerating operation condition and not in the Q flat region), the process proceeds to step 11 and the weighting The constant X _REV is set to zero, the simple average value Q _SIMPL calculated in step 1 this time is set as the weighted average value Q _AVREV this time, and the weighted average calculation in step 10 is not performed.

Even if it is determined in step 5 that the engine 1 is in the decelerating operation state, if it is determined in the next step 6 that the engine 1 is in the Q flat region, the process proceeds from the next step 7 to step 9. , _Was set to effectively suppress the intake pulsation in the steady operation state (set relatively small to weight the past weighted average value Q _AVREV )
The weighting constant X _REV is searched from the map (step 9)
Therefore, the intake pulsation in the Q flat region at the initial stage of deceleration can be smoothly smoothed.

In other words, even if the engine 1 is determined to be in the decelerating operation state and is in the operating state where the followability of the intake air flow rate should be originally secured, when the engine 1 is in the Q flat region, the followability is secured. The increase of weighting (reduction of weighting constant X _REV or avoiding the weighted average processing when step 11 is performed) for the latest detection value (current simple average value Q _SIMPL ) that is performed to prevent intake pulsation The basic fuel injection amount Tp does not fluctuate by smoothing. In the decelerating operation state, and when the operation is not in the Q flat operation area, the process proceeds to step 11 so that the weighted average calculation is not performed and the followability to the change of the intake air flow rate is secured.

When the calculation and setting of the weighted average value Q _AVREV is completed as described above, in the next step 12, whether or not the engine 1 is in the rapid acceleration operation state is set based on the throttle valve opening change rate ΔTVO. Here, for example, when the throttle valve opening change rate ΔTVO is 1.6 ° / 30 ms or more, it is determined that the engine 1 is in the rapid acceleration operation state, and when the rapid acceleration determination is made, the process proceeds to step 13.

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

In step 15, the correction amount ΔQ for correcting the detection delay of the air flow meter 4 in the rapid acceleration operation state of the engine 1
Is calculated according to the following formula.

ΔQ ← (Q _AVREV -Previous Q _AVREV ) K _MANI That is, the correction amount ΔQ is obtained by multiplying the coefficient K _MANI by the value _obtained by subtracting the previous weighted average value Q _AVREV from the weighted average value Q _AVREV calculated or set this time. To be The coefficient K _MANI
Is determined according to the collector volume of the intake manifold 2 and the responsiveness of the air flow meter 4, for example, 2.
The value should be around 6.

In the next step 16, the correction amount ΔQ calculated in step 15
Is determined to be a value exceeding zero, and the correction amount ΔQ>
When it is 0, the routine proceeds to step 17, where the flag is judged, and only when the correction amount ΔQ> 0 and the flag is 1, the routine proceeds to step 18 where the intake air flow rate Q is increased and corrected. On the other hand, when 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 Q _AVREV calculated in step 10 this time to perform increase correction. Weighted average value Q calculated in 10
_AVREV 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 in the upstream portion of the branch portion of the intake manifold 2, the volume of the intake passage on the downstream side of the fuel injection valve 5 is filled at the time of sudden acceleration. However, the correction amount ΔQ calculated in step 15 is used because there is a detection delay of the intake air flow rate Q that cannot be used for setting the fuel injection amount of the air flow meter 4. It is necessary to correct the amount by increasing the intake air flow rate Q after the sudden acceleration.
Since the intake pulsation is promoted if the increase correction by the correction amount ΔQ is performed even when is stable, in the present embodiment, in order to solve this, once the weighted average value Q _AVREV shows a decreasing tendency, a new The increase correction is not performed until the vehicle is suddenly accelerated.

When the engine 1 is rapidly accelerated and the first determination is made in step 13, the flag is set to 1 and the weighted average value Q _AVREV shows a decreasing tendency (until it is determined in step 16 that the correction amount ΔQ ≦ 0). Is corrected in step 18, but when the weighted average value Q _AVREV shows a decreasing tendency, the flag is set to zero in step 19, so that the engine 1 Even if the rapid acceleration state is determined, the final Q is set in step 20 so that the increase correction is not performed, and until the rapid acceleration operation state is again determined for the first time and the flag is set to 1. This prohibition state of the increase correction continues.

When the final Q is set in step 18 or step 20, the basic fuel injection amount Tp (← K × final Q / N; K is a constant) is calculated using the final Q in the next step 21. Although omitted in the present embodiment, the correction amount Ts based on the battery voltage, the air-fuel ratio feedback correction coefficient LAMBDA based on the air-fuel ratio detected by the oxygen sensor 9 and the cooling water temperature detected by the water temperature sensor 7 in another routine, etc. The basic fuel injection amount Tp is corrected and calculated by various correction factors such as COEF based on the above, and the final fuel injection amount Ti is set, and the injection pulse signal corresponding to this fuel injection amount Ti is injected in synchronization with the engine rotation. The fuel is output to the valve 5 and the fuel is injected and supplied to the engine 1 on / off.

<Effect of the Invention> As described above, according to the present invention, when it is determined that the engine is in the decelerating operation state and is in the Q flat operation region, even if the engine is in the acceleration / deceleration operating state, the intake air Since the increase in weighting for the latest detection value, which is performed to secure the followability to the flow rate change, is prohibited, the intake pulsation in the Q flat region at the initial stage of the deceleration operation is smoothly smoothed and the fluctuation of the fuel injection amount is suppressed. Since this can be prevented, there is an effect that the drivability during deceleration operation can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention, FIG. 2 is a system diagram showing an embodiment of the present invention, FIGS. 3 and 4 are flow charts showing control contents of the same embodiment, and FIG. Q
FIG. 6 is a graph showing a flat area, and FIG. 6 is a time chart for explaining conventional problems. 1 ... Engine, 2 ... Intake manifold, 3 ... Throttle valve, 4 ... Air flow meter, 5 ... Fuel injection valve, 6 ...
Control unit, 10 Crank angle sensor, 11
...... Throttle sensor

Claims (1)

[Claims] 1. An engine speed detecting means for detecting an engine speed, an intake air flow rate detecting means for detecting an intake air flow rate of the engine, and an engine operating state including the detected engine speed and intake air flow rate. In an electronically controlled fuel injection device for an internal combustion engine, comprising: a fuel injection amount setting means for setting a fuel injection amount by a fuel injection means; and a fuel injection means for injecting an amount of fuel set by the fuel injection amount setting means to the engine An acceleration / deceleration operation state determination means for detecting an opening degree of a throttle valve interposed in an intake system of the engine and determining an acceleration / deceleration operation state of the engine based on a change in the opening degree of the throttle valve; A weighted average that calculates the weighted average of the latest detected value of the intake air flow rate detected by the flow rate detection means and the value of the past intake air flow rate, and outputs the weighted average value to the fuel injection amount setting means as an intake air flow rate signal. Calculation means, and weighting variable means for increasing the weighting of the latest detection value in the weighted average by the weighted average calculation means when the acceleration / deceleration operation state of the engine is determined by the acceleration / deceleration operation state determination means, An intake amount flat operating region determining means for determining an intake amount flat operating region, which is an operating region in which the intake air flow rate does not change even if the opening of the throttle valve changes, and deceleration operation of the engine by the acceleration / deceleration operating state determining means. When the state is determined and the intake air amount flat operation region determining means determines that the intake air amount is in the flat air amount operating region, the weighting variable prohibition prohibits an increase in weighting for the latest detected value by the weighting variable device. An electronically controlled fuel injection device for an internal combustion engine, comprising: