JPH01216041A - Electronic control fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve air-fuel ratio control precision during transient running, by a method wherein phase advance processing is applied on a fundamental fuel injection amount determined from the opening of a throttle valve and the number of revolutions of an engine, and a difference between a phase advance fundamental injection amount and a fundamental fuel injection amount is used as an acceleration deceleration correction amount. CONSTITUTION:Based on a state amount of intake air, a first fundamental fuel injection amount is set by a set means A, and from the opening of a throttle and the number of revolutions of an engine, a second fundamental injection amount is set by a set means B. Based on a change in a second fundamental fuel injection amount, phase advance processing is applied in a change direction on a fundamental fuel injection amount by means of a set means C, and a phase advance fundamental fuel injection amount is set. An acceleration deceleration correction amount is set as a difference between the phase advance fundamental fuel injection amount and the second fundamental injection amount by a set means D, a fundamental fuel injection amount is corrected by a correction means E by adding it to a first fundamental injection amount, and based on a fundamental fuel injection amount after correction, a fuel injection amount is computed by a computing 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.

<Prior art> Conventionally, in an electronically controlled fuel injection system for an internal combustion engine, the intake air flow rate Q is detected as the state quantity of the intake air, and from this and the engine speed N, the basic fuel injection amount Tp = -Q /N(K
is a constant), or the intake pressure (intake negative pressure) PB is detected as the state quantity of the intake air, and the basic fuel injection amount Tp is calculated based on this. The method based on intake air flow rate Q is called L-jetro, and the method based on intake pressure PB is called D.
It's called JETRO. Then, the final fuel injection amount Ti=Tp −C0E is corrected by various correction coefficients C0EF based on water temperature etc. and voltage correction numerator s based on battery voltage.
Calculate F+Ts.

Then, at a predetermined timing synchronized with the engine rotation, a drive pulse signal having a pulse width corresponding to the fuel injection amount Ti is outputted to the electromagnetic fuel injection valve, thereby injecting and supplying fuel to the engine.

However, during acceleration, for example, the air-fuel ratio becomes lean due to a delay in the transport of wall flow fuel adhering to the inner wall of the intake passage, so the engine output does not respond well during acceleration, resulting in poor acceleration performance.

Generally, an acceleration increase correction coefficient KFIIEL is provided in the various correction coefficients C0EF, and the value of utL is set appropriately for the acceleration increase correction coefficient based on the amount of change in the throttle valve opening during acceleration. Although we are trying to improve performance, since the acceleration increase correction coefficient KFu is set based on map data, it is difficult to ensure the optimal fuel injection amount in all areas commensurate with the acceleration state, It was not possible to obtain good acceleration performance.

Therefore, based on the change in the basic fuel injection amount set based on the state quantity of intake air, the basic fuel injection amount is phase-advanced in the direction of the change, and the phase-advanced basic fuel injection amount is set.
By calculating the final fuel injection amount based on this phase advance basic fuel injection amount, the effect of wall flow fuel transport delay is eliminated not only during acceleration but also during transient operation including deceleration, and the air-fuel ratio A system has been proposed that improves control accuracy, output responsiveness, etc., and eliminates the need for man-hours for matching map data by setting the basic fuel injection amount during transient operation using calculations (Japanese Patent Application No. 62-281963). reference).

<Problems to be Solved by the Invention> However, when increasing the amount of acceleration or decreasing the amount of deceleration by such phase advance processing of the basic fuel injection amount, it is difficult to accurately adjust the basic fuel injection amount based on engine load fluctuations during acceleration and deceleration. If this is understood, the optimal control amount can be obtained, but in both L-JETRO and D-JETRO, fluctuations in the basic fuel injection amount due to intake pulsation are added, so acceleration increases and deceleration decreases are added more than necessary.
This resulted in deterioration of drivability and increase in GO and HC emissions, and there was still room for improvement.

In addition, FIG. 7 is a control characteristic diagram during acceleration in the prior art,
When the basic fuel injection amount Tp accurately captures the engine load fluctuation as shown by the broken line in the figure, the phase advance basic fuel injection amount PR
Although the optimal increase can be obtained by ETp, as shown in the solid line in the figure (when Tp fluctuates due to intake pulsation, an acceleration increase amount that is more than necessary and whose fluctuations are amplified is always added).

In view of these problems, the present invention makes it possible to secure the optimum fuel injection amount commensurate with the acceleration/deceleration state in all regions without being affected by intake pulsation, thereby reducing the amount of fuel injection during transient operation. The purpose is to improve fuel ratio control accuracy, improve drivability, and reduce Co and HC emissions.

<Means for Solving the Problems> Therefore, as shown in FIG.
The structure is such that a means F is provided.

A) First basic fuel injection amount setting means that sets the basic fuel injection amount based on the state quantity of intake air B) Separately from the first basic fuel injection amount setting means, the first basic fuel injection amount setting means sets the throttle valve opening degree and the engine rotation speed. C) A second basic fuel injection amount setting means for setting a basic fuel injection amount from said second basic fuel injection amount setting means. Phase advanced basic fuel injection amount setting means for setting advanced basic fuel injection amount D) Phase advanced basic fuel injection amount by the phase advanced basic fuel injection amount setting device and basic fuel injection amount by the second basic fuel injection amount setting device E) Acceleration/deceleration correction amount setting means for setting an acceleration/deceleration correction amount as the difference between the acceleration/deceleration correction amount and the basic fuel injection amount by the first basic fuel injection amount setting means Basic fuel injection amount correction means for correcting by adding F) Fuel injection amount calculation means for calculating the fuel injection amount based on the basic fuel injection amount corrected by the basic fuel injection amount correction means; The basic fuel injection amount setting means C is configured to set two types of phase advance basic fuel injection amounts having different phase advance amounts, and the acceleration/deceleration correction amount setting means C is configured to set two types of phase advance basic fuel injection amounts having different phase advance amounts. It is preferable to select the one with the largest absolute value and set the acceleration/deceleration correction amount.

(Function) In the above configuration, the basic fuel injection amount is set from the throttle valve opening degree and the engine speed, and based on the change in the basic fuel injection amount, a phase advance process is performed in the direction of the change to phase advance the basic fuel. The injection amount is set, and the acceleration/deceleration correction amount is set as the difference between this phase-advanced basic fuel injection amount and the original basic fuel injection amount.

According to this, the basic fuel injection amount determined from the throttle valve opening and engine speed can accurately capture engine load fluctuations without being affected by intake pulsation, and the optimal demand can be achieved using phase advance processing. It is possible to determine the optimal acceleration/deceleration correction amount by understanding the amount of acceleration/deceleration.

Then, the basic fuel injection amount set based on the state quantity of the intake air is corrected by adding the acceleration/deceleration correction amount to this, and the fuel injection amount is calculated based on the basic fuel injection amount obtained by this correction. It is.

In addition, two types of phase advance basic fuel injection amounts with different phase advance amounts are set, and the one with the largest absolute value is selected from these two types of phase advance basic fuel injection amounts to adjust the acceleration/deceleration correction amount. If this setting is made, the acceleration/deceleration correction amount can be gradually attenuated in the later stages of acceleration/deceleration, resulting in better performance.

<Example> An example of the present invention (in the case of L-JETRO) will be described below.

In FIG. 2, air is supplied to the engine l from an air cleaner 2 through a throttle valve 3 linked to an accelerator pedal and an auxiliary air control valve 5 installed in an auxiliary air passage 4 that bypasses the throttle valve 3. Air is sucked in through the manifold 6.

A fuel injection valve 7 is provided in each branch of the intake manifold 6 for each cylinder. The fuel injection valve 7 is an electromagnetic fuel injection valve that opens when the solenoid is energized and closes when the energization is stopped. Fuel is injected under pressure by a pump and adjusted to a predetermined pressure by a pressure regulator. Although this example is a so-called multi-point injection system, it may also be a single-point injection system in which a single fuel injection valve is provided in common to all cylinders, such as upstream of the throttle valve.

An ignition plug 8 is provided in the combustion chamber of the engine 1, which ignites a spark to ignite and burn the air-fuel mixture.

The control unit 9 includes a CPU and a ROM.

Equipped with a microcomputer including a RAM, an A/'D converter, and an input/output interface, it performs arithmetic processing based on input signals from various sensors and controls the fuel injection valve 7. Controls the operation of the auxiliary air control valve 5 and the spark plug 8.

However, below, only the control of the fuel injection amount by the fuel injection valve 7 will be explained.

As the various sensors mentioned above, a hot wire type air flow meter IO is provided in the intake passage upstream of the throttle valve 3, and detects the intake air flow rate Q. In addition, in the case of D-JETRO, an intake pressure sensor is installed in the intake manifold.
Detects intake pressure (inhalation negative pressure) PB.

Further, a crank angle sensor 11 is provided, and for example, in the case of a four-cylinder engine, a reference signal REF is provided for each crank angle of 180°.
and a unit signal PO3 for every 1 to 2 degrees of crank angle. Here, the engine speed N can be calculated by measuring the period of the reference signal REF or the number of occurrences of the unit signal PO3 within a predetermined time.

Further, the throttle valve 3 is provided with a potentiometer-type throttle sensor 12 to detect the throttle valve opening degree α.

Further, a water temperature sensor 13 is provided facing the water jacket of the engine 1 to detect the engine cooling water temperature TW.

Here, a microcomputer (CPU) built into the control unit 9 performs arithmetic processing and controls the fuel injection amount according to a program on a ROM shown as flowcharts in FIGS. 3 to 5.

Next, the state of the arithmetic processing of the microcomputer in the control unit 9 will be explained with reference to the flowcharts shown in FIGS. 3 to 5.

Fig. 3 shows a routine for determining the basic fuel injection amount Tp (hereinafter Tp obtained from α-N will be referred to as "Tp") from the throttle valve opening α and the engine speed N (hereinafter referred to as α-N). (for example, every 10a+s).

Step 1 (denoted as Sl in the figure; the same applies hereinafter): The throttle valve opening degree α detected based on the signal from the throttle sensor 12 is read.

In step 2, the throttle valve passing air flow rate ATVO is calculated from the throttle valve opening α with reference to the map, and the valve opening duty l5CDUTY, which is the opening control signal to the auxiliary air control valve 5, is calculated with reference to the map. Adding the air flow rate Al5C passing through the auxiliary air control valve and the predetermined leakage ALEAK in the idle adjustment screw, etc., the intake air flow rate AQ (rrt/h) = volumetric flow rate.
Find ATVO+Al5C+ALEAK.

In step 3, the basic fuel injection amount Tp corresponding to the intake pressure is
(The intake pressure PB obtained in step 21 of FIG. 5, which will be described later, can be used in the case of D-JETRO) and the suction negative pressure characteristic ψ (%) is determined by referring to a map.

In step 4, the intake air flow rate AQ is multiplied by the intake negative pressure characteristic ψ, and the mass flow rate, the intake air flow rate G (to the temple) = AQ・
Calculate φ.

Here, since G is determined by the following formula (1), ψ is determined by the following formula (2
), and a map of ψ is created using representative atmospheric condition data with atmospheric pressure PA etc. constant. This is because L-JETRO does not have an atmospheric pressure sensor or an intake temperature sensor. The value of ψ is kept constant in the sonic region where the intake pressure PB is below a predetermined value (-340■Hg), and decreases as the intake pressure PB increases in the region where the intake pressures P and B exceed the predetermined value. It has the characteristics of

G=AQ・ψ゛・C・(PA・ρ) (1) In step 5, based on the intake air flow rate G and the engine speed N, the basic fuel injection amount Tp'='・G/ N (K'
is a constant). This basic fuel injection amount Tp” is α−
This is the basic fuel injection amount obtained from N.

Therefore, steps 1 to 5 correspond to the second basic fuel injection amount setting means.

In step 6, a weighting constant X (-1 to 255) is calculated by multiplying the value obtained by referring to the map from the water temperature Tw and the value obtained by referring to the map from the basic fuel injection amount Tp. .

FIG. 4 shows the basic fuel injection amount PRETp obtained by performing phase advance processing on the basic fuel injection amount Tp' obtained from α-N.
In this routine, the acceleration/deceleration correction amount DLTTp is determined based on the reference signal RE of the crank angle sensor 11.
In the case of a 4-cylinder engine, it is executed every % rotation of the engine in synchronization with F.

In step 11, the phase advance basic fuel injection amount PR is calculated based on the basic fuel injection amount Tp' obtained from α-N according to the following equation.
Calculate ETp. Tp''., 4 is Tp'' before % rotation.

Here, 'rp'=Tp'.If L4+ΔTp',
It becomes as follows.

Therefore, for weighting, phase advance processing can be performed by setting the constant X to an appropriate value between 1 and 255.

This step 11 (and step 13 to be described later) corresponds to phase advance basic fuel injection amount setting means.

In step 12, Tp' is changed to Tp' for the next calculation. , and assign it to .

In step 13, the decreasing characteristic phase advance basic fuel injection amount PRETp1 is determined according to the following equation. PRETpo*a
is the larger of PRETP or PRETpl before % rotation. n and m are constants.

PRETp 1←PRETPoLd PRETp-
For example, n=8. If m-1, PRETpl-
(7/8)xPRETp, ta.

In step 14, l PRETP I and l PRET
Compare with pH.

If l PRETp I > l PRETp 11 (
(in the early stage of acceleration/deceleration), the process proceeds to step 15 and the basic fuel injection amount Tp' is subtracted from the phase advanced basic fuel injection amount PRETp to calculate the acceleration/deceleration correction amount DL which is the phase advanced amount.
TTp=PRETp-T, p' is calculated, and in the next step 16, PRETp is assigned to PRETPota.

If I PRETp l≦l PRETp 1 l (
(in the case of the latter half of acceleration/deceleration), the process proceeds to step 17 and subtracts the basic fuel injection amount Tp' from the basic fuel injection amount PRETp 1 with the decreasing characteristic phase advance, thereby accelerating/decelerating correction amount DLTTp-PRETpl- Tp' is calculated, and in the next step 18 PRETpl is changed to PRETP.
-Assign to ta.

Here, steps 14, 15, and 17 correspond to acceleration/deceleration correction amount setting means.

FIG. 5 shows a routine for calculating the final fuel injection amount TI, which is executed at predetermined time intervals (for example, ioms).

In step 21, the basic fuel injection amount Tp=KQ/N (K is a constant) is calculated from the intake air flow rate Q detected based on the signal from the air flow meter 10 and the engine speed N. In the case of D-JETRO, the basic fuel injection amount Tp is set based on the intake pressure PB. This step 21 corresponds to the first basic fuel injection amount setting means.

In step 22, the acceleration/deceleration correction amount DLTTp is added to the basic fuel injection amount Tp to correct the basic fuel injection amount Tp as shown in the following equation. This step 22 corresponds to the basic fuel injection amount correction means.

Tp+Tp+DLTTp In step 23, the fuel injection amount TI is calculated according to the following equation. C0EF is various correction coefficients, and Ts is voltage correction bone. This step 23 corresponds to the fuel injection amount calculation means.

Ti=Tp-COEF+Ts When the fuel injection amount Ti is calculated in this way, a drive pulse signal with a pulse width corresponding to this Ti is output to the fuel injection valve 7 at a predetermined timing synchronized with the engine rotation.
Fuel injection takes place.

Through such control, as shown in Fig. 6, a phase advance basic fuel injection amount PRETp that is not affected by intake pulsation is obtained, and this is added to the basic fuel injection amount Tp that is affected by intake pulsation to correct it. Even if the corrected Tp is used, the original intake pulsation component will not be amplified.In addition, in the late acceleration period, the PRE with a decreasing characteristic will be used as the phase advance basic fuel injection amount.
Since Tpl is used, better drivability can be obtained by gradually attenuating the acceleration/deceleration correction amount in the latter half of acceleration.

(Effects of the Invention) As explained above, according to the present invention, the basic fuel injection amount can be set based on the throttle valve opening and the engine speed to accurately detect engine load fluctuations without being affected by intake pulsation. This basic fuel injection amount is subjected to phase advance processing, and the difference between the phase advance basic fuel injection amount and the original basic fuel injection amount is used as the acceleration/deceleration correction amount, which improves the accuracy of air-fuel ratio control during transients and improves operational efficiency. The effects of improved performance and reduced emissions of CO and HC can be obtained.

In addition, two types of phase advance basic fuel injection amounts with different phase advance amounts are set, and the one with the largest absolute value is selected from these two types of phase advance basic fuel injection amounts to adjust the acceleration/deceleration correction amount. If this setting is made, the acceleration/deceleration correction amount can be gradually attenuated in the later stages of acceleration/deceleration, resulting in better drivability.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a system diagram showing an embodiment of the present invention, FIGS. 3 to 5 are flow charts showing control contents, and FIG. FIG. 7 is a control characteristic diagram during acceleration in the prior art. 1... Engine 3... Throttle valve 7... Fuel injection valve 9... Control unit 10.
...Air flow meter 11...Crank angle sensor 12...Throttle sensor Patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio Sasashima Figure 3 10m5@chi Figure 4 Figure 6 Figure 7

Claims (2)

[Claims] (1) A first basic fuel injection amount setting means that sets the basic fuel injection amount based on the state quantity of intake air; a second basic fuel injection amount setting means for setting the basic fuel injection amount from the number; and a phase advancing process in the direction of the change based on a change in the basic fuel injection amount by the second basic fuel injection amount setting means. a phase advance basic fuel injection amount setting means for setting a phase advance basic fuel injection amount; a phase advance basic fuel injection amount by the phase advance basic fuel injection amount setting means; and a basic fuel injection by the second basic fuel injection amount setting means. an acceleration/deceleration correction amount setting means for setting an acceleration/deceleration correction amount as a difference between the acceleration/deceleration correction amount and the basic fuel injection amount by the first basic fuel injection amount setting means; basic fuel injection amount correction means for correcting by adding the basic fuel injection amount, and fuel injection amount calculation means for calculating the fuel injection amount based on the basic fuel injection amount corrected by the basic fuel injection amount correction means. An electronically controlled fuel injection device for an internal combustion engine, characterized in that: (2) The phase advance basic fuel injection amount setting means sets two types of phase advance basic fuel injection amounts with different phase advance amounts, and the acceleration/deceleration correction amount setting means sets two types of phase advance basic fuel injection amounts with different phase advance amounts. Claim 1 characterized in that the acceleration/deceleration correction amount is set by selecting one of the injection amounts with a large absolute value.
Electronically controlled fuel injection device for the internal combustion engine as described.