JPH02204660A - Fuel supply controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To perform highly accurate air-fuel ratio control as possible as it can be even at time of transient driving by compensating request fuel supply in a specified crank angle different from the setting timing on the basis of a forecast of variation in a load value at time of the transient driving. CONSTITUTION:A load value operational means A finds an engine load value from a parameter setting an intake system opening area of a throttle valve and an idling control valve or the like, and engine speed, and the first differential value and the second differential value are operated by a differential value operational means B and time ranging from load value operation time to a specified crank angle by a time operational means C, respectively. A compensation value operational means D finds an adjustable compensation value of fuel quantity to be fed synchronously with engine speed commensurate to an estimate variation of the load value of up to the specified crank angle and an interrupt supply compensation value at time of transient driving detection on the basis of these first and second differential values and required time up to the specified crank angle, thus compensation control is performed by a control means E. Thus improvement in transient driving performance and amelioration in exhaust emission control are well promotable.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a fuel supply control device for an internal combustion engine, and in particular to a device that performs correction control of fuel supply amount during transient operation with high accuracy and improves transient operation performance. Regarding.

<Prior Art> The following types of control devices for internal combustion engines are known. The intake air flow rate and intake pressure are detected as state quantities related to the intake air, and the basic fuel supply amount T is determined based on these and the detected value of the engine speed.

Calculate. Then, the basic fuel supply amount T is adjusted by various correction coefficients C0E set based on operating conditions such as engine temperature.
F, a feedback correction coefficient α set based on the air-fuel ratio obtained through detection of the oxygen concentration in the exhaust gas, and a correction numerator based on the battery voltage.

Calculate the final fuel supply amount TI by correcting it by
, =T, -COEF-LAMBDA+T, ), the calculated amount of fuel is supplied to the engine by a fuel injection valve or the like.

<Problems to be Solved by the Invention> By the way, in a device that calculates and sets the fuel supply amount and controls it electronically, it is necessary to use an air flow meter for detecting the intake air flow rate and a pressure sensor for detecting the intake pressure during transient operation. This results in a detection delay and a calculation delay in the control device.

For this reason, for example, during acceleration, the detected values are smaller than the actual intake air flow rate and intake pressure, so the fuel supply amount is also set smaller, and the air-fuel ratio becomes leaner, resulting in NOx (nitrogen oxidation). This may result in acceleration shock or deterioration of acceleration response due to an increase in the amount of gas discharged or a delay in the response of the average effective pressure.

FIGS. 6(A) to 6(H) show various states of the intake pressure detection type during acceleration.

In view of this, as seen in Japanese Patent Laid-Open No. 60-201035, changes in intake air flow rate and intake pressure are predicted and corrected based on the rate of change in throttle valve opening, and an amount of fuel commensurate with the correction value is supplied. There are some systems that suppress changes in the air-fuel ratio and improve transient operating performance.

However, based on the rate of change of the throttle valve opening,
Even if an attempt is made to increase or decrease the amount of fuel, the intake air flow rate and intake pressure do not change linearly with the throttle valve opening, so matching requires a huge amount of man-hours and reduces the added value of the control unit. .

Further, although detection delays and calculation delays are dealt with, the accuracy is poor because the time difference between the detection time and the suction stroke is not taken into consideration.

Furthermore, some systems calculate the second-order differential value of the intake pressure to predict the amount of load fluctuation and correct the fuel supply amount.
Since there is a large delay in the intake pressure with respect to changes in the throttle valve opening, and intake pulsations are captured, it is not possible to accurately perform correction commensurate with the cylinder intake air amount.

Therefore, during transient operation, the applicant calculated the load (cylinder intake air amount) from the rate of change of the throttle valve opening and the engine speed.
We proposed a system that predicts the amount of fluctuation and corrects and controls the fuel supply amount in accordance with the amount of load fluctuation (Japanese Patent Application No. 62-2).
No. 69467).

However, in this method, the load fluctuation amount is predicted based on a primary rate of change obtained from the latest detected value of the throttle valve opening detected at predetermined intervals and the previous detected value. Therefore, during acceleration, the air-fuel ratio tends to become lean at the beginning and rich at the end, and
During deceleration, the air-fuel ratio tended to become richer in the early stages and leaner in the later stages. This is caused by a discrepancy due to the assumption that the throttle valve opening varies linearly, whereas in reality it varies linearly (see FIG. 7).

The present invention was made in view of such conventional circumstances,
We have developed a fuel supply control device for an internal combustion engine that solves the above problems by having a configuration that accurately predicts fluctuations in engine load based on changes in throttle valve opening, etc., and performs correction control of fuel supply amount. The purpose is to provide.

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention provides a load calculation means for calculating an engine load based on a parameter that determines the opening area of the intake system and the engine speed. , a differential value calculating means for calculating a first-order differential value and a second-order differential value per unit time of the load amount, and a time calculating means for calculating an estimate of the time required from when the load amount is calculated to a predetermined crank angle. and the first-order differential value and the second-order differential value,
a correction amount calculating means for calculating a correction amount of the fuel supply amount commensurate with an estimated change in the load amount until the predetermined crank angle is reached based on the time required to reach the predetermined crank angle; and a control means for correcting and controlling the fuel supply amount.

In addition to the throttle valve opening, the parameters that determine the opening area of the intake system used for calculation by the load calculation means include the throttle valve opening when an idle control valve is installed in the auxiliary air passage that bypasses the throttle valve. It may be based on the idle control valve opening degree and the idle control valve opening degree.

Further, the correction amount calculation means may calculate a correction amount for increasing or decreasing the amount of fuel supplied in synchronization with the engine rotation, and separately or in addition to this calculation, the correction amount calculation means may also calculate a correction amount for increasing or decreasing the amount of fuel supplied in synchronization with the engine rotation. A configuration may also be adopted in which the correction amount that is interrupt-supplied at the same time is calculated.

Function> The load amount calculation means calculates the engine load amount based on the engine speed and parameters that determine the opening area of the intake system, such as the throttle valve opening degree, the throttle valve opening degree and the idle control valve opening degree.

The differential value calculating means calculates a single differential value and a second differential value of the load amount.

On the other hand, the time calculation means calculates the time from when the load amount is calculated to the predetermined crank angle.

The correction amount calculating means synchronizes with the engine rotation in accordance with the estimated amount of change in the load amount up to a predetermined crank angle based on the first differential value and the second differential value of the load amount and the time required to reach the predetermined crank angle. The amount of correction that increases or decreases the amount of fuel supplied, and the amount of correction that is interruptively supplied at the same time as transient operation of the engine is detected.

Then, the control means corrects and controls the fuel supply amount based on the correction amount.

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

In FIG. 2 showing the configuration of an embodiment, an internal combustion engine 1 includes an air cleaner 2. Intake duct 3. Air is drawn in via the throttle chamber 4 and the intake manifold 5.

The air cleaner 2 is provided with an intake temperature sensor 6 that detects intake air (atmospheric) temperature. The throttle chamber 4 is provided with a throttle valve 7 that operates in conjunction with an accelerator pedal (not shown) to control the intake air flow rate Q. A throttle sensor 8 is attached to the throttle valve 7, which detects its opening degree TVO and includes an idle switch 8A that is turned ON at the idle position. The intake manifold 5 downstream of the throttle valve 7 is provided with an intake pressure sensor 9 for detecting intake pressure, and an electromagnetic fuel injection valve 10 is provided for each cylinder. The fuel injection valve 10 is driven to open by an injection pulse signal from a control unit 11 containing a microcomputer (described later), and fuel is fed under pressure from a fuel pump (not shown) and controlled to a predetermined pressure by a pressure regulator into the intake manifold 5. Supply injection. Furthermore, a water temperature sensor 12 that detects the cooling water temperature T8 in the cooling jacket of the engine 1 is provided, and an oxygen sensor that detects the air-fuel ratio in the intake air-fuel mixture by detecting the oxygen concentration in the exhaust gas in the exhaust passage 13. 14 are provided.

The control unit 11 counts the crank angle unit angle signal output from the crank angle sensor 15 for engine rotation speed detection in synchronization with the engine rotation for a certain period of time, or measures the period of the crank angle reference angle signal to control the engine speed. Detect the rotation speed N.

In addition, a vehicle speed sensor 16 for detecting vehicle speed in the transmission. A neutral sensor 17 is provided to detect the neutral position, and these signals are input to the control unit 11.

Additionally, an auxiliary air passage 18 bypassing the throttle valve 7
is provided with an idle control valve 19 for controlling the idle speed.

The control unit 11 calculates the fuel injection amount T1 based on the various detection signals detected as described above, and also drives and controls the fuel injection valve 10 based on the set fuel injection amount T1. The idle rotation speed is controlled by controlling the opening degree of the idle control valve 19.

Next, the operation will be explained according to the flowcharts shown in FIG. 3 and subsequent figures.

FIG. 3 shows a fuel injection amount setting routine that is executed every set period (for example, 10m5).

In step 1 (denoted as S in the figure), detection signals from various sensors are input.

In step 2, the difference TM (= FRC
FRCOLD ) is calculated.

In step 3, a value TM2 is calculated by subtracting the TM from the latest cycle TREF for each reference signal input REF calculated in the routine.

In step 4, the value of TM2 is converted by multiplying the value TM2S, whose unit time is the execution cycle of this routine, by a conversion constant R (TM2S=TM2.R). For example, if the execution cycle of this routine is 10m5. When the count period of the free run counter is 1rLS, it becomes R-1/10.

In step 5, the opening area A of the bypass passage 18 is determined from the throttle valve opening TVO, the opening area A T H+, and the opening duty ratio I S Cooyy of the idle control valve 19.
ISC is determined by searching from a map stored in the ROM, and these are added to determine the total aperture area A.

In step 6, the basic volumetric efficiency QCYL for A/N
^. is searched from a map stored in the ROM of the microcomputer.

In step 7, 2 is set as the first-order lag correction coefficient for the intake system opening area change of the intake volumetric efficiency QCIL, which will be described later, and the intake pressure P! It is found for the product of l and engine speed N,
Search from the map stored in the ROM of the microcomputer.

In step 8, the volumetric efficiency Q cyta corresponding to the intake opening area detection method is calculated according to the following equation.

QcyLA=Qevtao 'Kz +QcvLAo
to ° (I Kz ) where QcytAoLo
is the previous value of the volumetric efficiency Q CYLA, and during steady operation where the opening area A does not change, Q cy+, Ao = Qcv
t, aoto, and the volumetric efficiency Q CYLA- is constant, but during transient operation when the opening area A changes, there is a delay in the change in the volumetric efficiency QcvpA due to the manifold volume downstream of the throttle valve, so this can be changed by Approximately find it using a fixed first-order lag system.

In step 9, the basic fuel injection amount TPA corresponding to the opening area detection method is calculated using the above values according to the following equation.

TFA=　KcoHs　゛　QcvtaHowever, K.

□ is a constant. The basic fuel injection amount TPA corresponds to the load amount, and therefore the portion from step 1 to step 9 corresponds to the load amount calculation means.

In step 10, the one-time differential value dTPA of the basic fuel injection amount T7, which is the load amount, is calculated using the following equation.

dTp^=Tde^-TFAOL11 However, as described later, TPAOLD is the basic fuel injection amount T.
This is the previous value of PA.

In step 11, the basic fuel injection amount TPA, which is the load amount, is
The quantitative differential value ddTpA of is calculated using the following equation.

d d TPA= d TPA d TPAOL11
However, as described later, dTpa. LD is the one-time differential value dT
This is the previous value of 0.

The above steps 10 and 11 correspond to the differential value calculation means.

In step 12, for the next calculation, the step 8
The volumetric efficiency Q cvLA determined by the previous value Q eYLAO
LD + The basic fuel injection amount TPA obtained in step 9 is the previous value TPAOLD + - times differential value dTpa is the previous value dT
Set each as PAOL11.

In step 13, these basic fuel injection ITPA
The average load change rate Dantp (=
d TPA + d d TPA).

In step 14, the time required to reach a predetermined crank angle set near the end of the intake stroke is calculated according to the following equation.

TIME=TM2S+TREFS (1+x/180)
Here, the fuel injection timing is performed in synchronization with the input of the reference signal REF 90' before top dead center for each cylinder, TREFS is a value obtained by multiplying the period TREF by a conversion constant R, and χ is the injection timing. This is the angle from when the next reference signal REF is input to the predetermined crank angle.

In step 15, a correction amount KTTP commensurate with the amount of change in load estimated based on the rate of change in load amount Dantp and the required time TIME is calculated using the following equation. This step 15 corresponds to the correction amount setting means.

KTTP-Dantp-T IME In step 16, the basic volumetric efficiency Qcyt,rs for a predetermined value is determined by the following equation. is obtained by searching from a map stored in ROM.

In step 17, the volumetric efficiency Q corresponding to the intake pressure detection method is determined.
CYLPR is calculated using the following equation.

Q cvLrm = QcyLpmo-KFLAT Here, K FLAT is a minute correction coefficient obtained by searching from a three-dimensional map stored in ROM for intake pressure P and engine speed N in BGJ (background job). It is.

In step 18, the basic fuel injection amount T1,8 corresponding to the intake pressure detection method is calculated using the following equation.

TPPII=KCOND-QcvLpm・Pi
-KTA Here, KTA is a volumetric efficiency correction coefficient set for water temperature, and is obtained by searching from the map stored in the ROM in the aforementioned BGJ.

In step 19, the fuel injection amount T1 without transient correction is performed.
is calculated by the following formula.

T1=2・T, □・LAMBDA −C0EF+T.

Here, LAMBDA is a feedback correction coefficient set by proportional-integral control or the like based on the air-fuel ratio detection signal from the oxygen sensor 14.

In step 20, the fuel injection amount T1 is changed to the correction amount K.
Final fuel injection amount M T + corrected using TTP
is calculated using the following formula.

MT+ = T+ +2・KTTP Note that T2□ and KTTP are set as the amount per revolution for each cylinder, and since injection is performed every two revolutions, each should be doubled when setting the injection amount. .

FIG. 4 shows the calculation of the period TREF and its converted value TREFS, as well as the fuel injection amount MT.

The routine that outputs the signal is shown below. This routine is executed every time the reference signal REF outputted from the crank angle sensor 15 for each stroke phase crank angle between cylinders (for example, 180 degrees in the case of a four-cylinder, four-stroke engine) is input.

In step 21, the current value F of the free run counter is
The period TREF is calculated by subtracting the previous value F RCOLD from RC.

In step 22, the current value FRC is set as the previous value FRC0LD for the next calculation.

In step 23, the period TREF is multiplied by a conversion constant R to calculate a conversion value TREFS.

In step 24, a pulse signal having a pulse width corresponding to the set fuel injection amount MT1 is applied to the cylinder (90° before the top dead center of the intake stroke) corresponding to the input of the reference signal REF.
output to the fuel injection valve 10 of As a result, an amount of fuel equivalent to MT1 is injected and supplied into the intake passage 2 from the fuel injection valve 10.

Here, the free run counter and step 2 in FIG.
1 to 23 and steps 2 to 4.14 in FIG. 3 correspond to the time calculation means.

Although not shown, the intake pressure P is sampled at a period of, for example, every 4 ms.

According to such control, during transient operation, the load amount (To)
The change rate Dantap of the load amount obtained from the same-machine component value dTPA and the dihedral differential value ddTPA, and the time TIME from when the fuel injection amount is set until the predetermined crank angle at which the load amount corresponds to the fuel injection amount to be supplied. The amount of change in the load amount is estimated based on the amount of change in the load amount, and a correction amount for the fuel supply amount commensurate with the estimated amount of change is set. It is possible to improve the accuracy of air-fuel ratio control during operation and to improve transient operation performance as much as possible.

Changes in various state quantities during acceleration operation in this example are shown in the fifth column.
As shown in the figure.

In addition, although the above embodiment shows the setting of the correction amount when increasing the fuel supply amount during acceleration, it is possible to similarly predict the amount of decrease in the load amount during deceleration operation and set the deceleration correction amount. If you do this, you can improve the deceleration performance.

Further, the present invention can be applied to not only the increase/decrease correction of the fuel supply amount in synchronization with the engine rotation as described above, but also the interrupt correction control in which fuel is supplied almost simultaneously with acceleration detection.

In this case, the crank angle sensor 15, which outputs a minute crank angle unit angle signal as described above, detects the crank angle during acceleration detected by the rate of change of the throttle valve opening TVO, etc. The required time corresponding to the angular difference from the crank angle to the predetermined crank angle may be determined from the period of the REF signal, and the correction amount determined by the same calculation formula as in step 15 may be immediately injected and supplied. Alternatively, a timer may be activated for each cylinder at the injection start timing in synchronization with the engine rotation, and at the time of interrupt injection, the interrupt correction amount may be calculated using a value obtained by subtracting the timer measurement time from the TATIME as the required time.

In addition, in this embodiment, the basic fuel injection amount T7 is used as the load amount.
Although the first differential value and the quantitative differential value are determined, the first differential value and the quantitative differential value of the basic fuel injection amount T0 may be determined by using the volumetric efficiency QcvL as the load amount.

Furthermore, the present invention is based on a fuel supply amount setting method based on intake pressure detection, and has been applied to setting a correction amount during transient operation. It can be applied to a system based on a fuel supply amount setting method, and furthermore, it can be applied to a system based on a system in which the fuel supply amount is set by detecting the throttle valve opening and engine speed even during non-transient operation.

<Effects of the Invention> As explained above, according to the present invention, the required fuel supply amount at a predetermined crank angle different from the set timing during transient operation can be satisfied by setting the correction amount based on the prediction of the amount of change in the load amount. Therefore, even during transient operation, air-fuel ratio control can be performed with the highest possible precision, thereby improving transient operation performance and exhaust emissions.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 is a block diagram showing the configuration of the present invention.
FIGS. 3 and 4 are flowcharts showing various routines of the embodiment of the present invention, and FIG.
The figure is a time chart showing changes in various state quantities in the same example as above, and Figures 6 (A) to (H) are various states, air-fuel ratio, three-way catalyst conversion efficiency, and NOx in the acceleration example of the conventional example. , Co, and HC, and FIG. 7 is a diagram showing the conventional state during acceleration. 1... Engine 7... Throttle valve torque sensor
9...Intake pressure sensor Ha 11...Control unit angle sensor 8...Slot 10...Fuel injection 15...Cla Figure 2 Patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Sasashima Fujio

Claims (4)

[Claims] (1) Load calculation means for calculating an engine load based on a parameter that determines the opening area of the intake system and the engine speed, and calculating a first differential value and a second differential value of the load amount per unit time. time calculation means for estimating and calculating the time required from when the load amount is calculated to the predetermined crank angle; correction amount calculation means for calculating a correction amount of fuel supply amount commensurate with the estimated change in load amount up to a predetermined crank angle based on time, and control for correcting and controlling the fuel supply amount based on the calculated correction amount. 1. A fuel supply control device for an internal combustion engine, comprising: means. (2) The parameter that determines the opening area of the intake system is the throttle valve opening or the throttle valve opening and the opening of an idle control valve installed in an auxiliary air passage that bypasses the throttle valve. Fuel supply control device for internal combustion engines. (3) The fuel supply control device for an internal combustion engine according to claim 1 or 2, wherein the correction amount calculation means calculates a correction amount for increasing or decreasing the amount of fuel supplied in synchronization with engine rotation. (4) The fuel supply control device for an internal combustion engine according to claim 1 or 2, wherein the correction amount calculation means calculates the correction amount that is interruptedly supplied at the same time as the transient operation of the engine is detected.