JPH03260347A - Fuel injection control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To compensate an intake delay due to a phase difference by obtaining an opening change speed based on opening change of a throttle valve and correcting the opening based on the opening change speed also determining a fuel injection amount based on this correction opening and an engine speed. CONSTITUTION:An opening change speed is calculated by a means M1 based on opening change of a throttle valve detected by a means A. An opening correction amount of the throttle valve is set by a means M2 based on the opening change speed and an engine speed. Further this correction opening is calculated by a means M3 after correcting a throttle valve opening based on the opening correction amount. On the other hand, an intake air amount is estimated by a means M4 based on the correction opening and the engine speed. A fuel injection amount is calculated by a means M5 based on the intake air amount and the engine speed. A drive pulse signal corresponding to the fuel injection amount is output to an injector 10 from a means M6 in the predetermined timing synchronized with the engine speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection control device for an internal combustion engine applied to a vehicle, etc., and more specifically, a fuel injection control device for controlling fuel injection based on a throttle valve opening and an engine speed. The present invention relates to a fuel injection control device for an internal combustion engine that can appropriately control a transient fuel injection amount based on a rate of change in a throttle valve opening.

[Conventional technology]

As a conventional fuel injection control device for an internal combustion engine, the throttle valve opening degree α and the engine speed N are detected, the intake air amount Q is estimated by a map search using α and N as parameters, and the basic fuel injection amount is estimated based on this. Injection amount Tp −KXQ/
Set N (K is a constant). There is a fuel injection control device for an internal combustion engine using an α-N control method.

In this type of fuel injection control device, the fuel injection amount is determined before the intake stroke of the cylinder to be injected. The opening degree of the throttle valve and the engine speed are different at the end of the stroke.

Therefore, during a transient period, as shown in FIG.
Before the intake stroke of cylinder # in the figure, the intake air amount Q is determined from the throttle opening and engine speed at point A.

Estimate and calculate the intake air amount Q. The fuel injection amount is determined based on the illusion. However, the amount of air required by the engine,
In other words, the actual intake air amount Q of the #1 cylinder at point B (at the end of the intake stroke) is, for example, because the throttle opening and engine speed at point B during acceleration are larger than at point A.
There is a difference between the estimated intake air JIQ of the #1 cylinder and the actual intake air amount Q.

-Q. -ΔQ difference in intake air amount occurs. Therefore, even if the fuel injection amount is determined based on the estimated intake air amount,
During transient periods, the air-fuel ratio fluctuates.

In other words, during acceleration when the throttle valve opens further from a predetermined open state, the air-fuel ratio tends to be lean, as shown by the solid line in Figure 3 (C), and the throttle valve changes from the open state to the closed state. During deceleration, the air-fuel ratio tends to be rich.

Therefore, instead of setting the air-fuel ratio arbitrarily during a transient period, the amount of accelerator depression and engine speed are detected, the required air amount is predicted from these values, and the fuel supply amount is adjusted to the value corresponding to this required air amount. The prior art that changes the
It is described in Publication No. 31,35.

[Problem to be solved by the invention]

By the way, in the above-mentioned prior art, the required amount of air is predicted from the amount of depression of the accelerator pedal and the engine speed, and the amount of fuel supplied is adjusted to the value corresponding to the required air flow rate while giving an appropriate temporary delay to the amount of depression of the accelerator pedal. Since the air flow rate is changed, there is a problem in that the accuracy of estimating the air flow rate is poor and the air-fuel ratio fluctuates.

Further, when the throttle valve opening during the transient period changes as shown by the solid line in FIG. 3(a), the intake air amount becomes the intake air amount shown by the dotted line in FIG. 3(b). This uncorrected cylinder intake air amount is smaller than the target cylinder intake air amount shown by the solid line, and this difference is between the actual throttle valve opening shown by the solid line in Fig. 3(a) and the corrected throttle valve opening shown by the dotted line. This is due to the phase difference between the

The present invention has been made to address the above-mentioned problems, and its purpose is to calculate the intake air It is an object of the present invention to provide a fuel injection control device for an internal combustion engine that can stabilize the air-fuel ratio by correcting a throttle opening that is a parameter.

[Means to solve the problem]

In order to achieve the above object, a fuel injection control device for an internal combustion engine according to the present invention, as shown in FIG. A fuel injection control device for an internal combustion engine, which has a detection means, estimates an intake air amount from a throttle valve opening degree and an engine speed, and sets a fuel injection amount based on the intake air amount and the engine speed, Throttle valve opening change rate calculation means M1 that calculates the throttle valve opening change rate from the throttle valve opening change rate, and sets the throttle valve opening correction amount based on the throttle valve opening change rate and engine speed. a throttle valve opening correction amount setting means M2, a corrected throttle valve opening calculation means M8 for calculating a corrected throttle valve opening by correcting the throttle valve opening by the throttle valve opening correction amount, and the correction throttle valve. An intake air amount estimating means M4 that estimates the intake air amount based on the opening degree and the engine speed; a fuel injection amount calculation means M5 that calculates the fuel injection amount based on the estimated intake air amount and the engine speed; It includes a drive pulse signal output means M6 that outputs a drive pulse signal corresponding to the calculated fuel injection amount to the injector at a predetermined timing synchronized with engine rotation.

[For production]

With the above configuration, the throttle valve opening change rate is calculated from the throttle valve opening change rate, the throttle valve opening correction amount is set based on the throttle valve opening change rate and the engine rotation speed, and the throttle valve opening correction amount is calculated based on the throttle valve opening change rate and the engine rotation speed. The intake air amount is estimated based on the corrected throttle valve opening obtained by correcting the throttle valve opening and the engine speed, and the fuel injection amount is calculated based on the estimated intake air amount and engine speed. Then, a drive pulse signal corresponding to this fuel injection amount is output to the injector at a predetermined timing synchronized with engine rotation.

Therefore, during the transient period, the fuel injection amount is set according to the transient state, and as a result, the air-fuel ratio during the transient period is optimized.

〔Example〕

Hereinafter, the present invention will be described in detail based on the drawings.

In FIG. 2, reference numeral l denotes an engine body, and each intake boat 2 formed on the cylinder head 2 of this engine body l
An intake manifold 3 is communicated with a, a throttle chamber 5 is communicated with the intake manifold 8 via a collector chamber 4, and an air cleaner 7 is attached to the upstream side of the throttle chamber 5 via an intake pipe 6.

Furthermore, a throttle opening sensor 9a, which is an example of a throttle valve opening detection means, and an idle switch 9b, which detects when the throttle valve is fully closed, are connected to the throttle valve 5a provided in the throttle chamber 5.

Also, each intake bow in intake manifold 3)
An injector IO is arranged immediately upstream of 2a, and further,
A cooling water temperature sensor 11 faces the water jacket Ia of the engine body 1.

Further, a crank rotor 14 is connected to the crankshaft 13 of the engine body 1, and a crank angle sensor 15, which is an example of engine rotation speed detection means, is provided opposite to the peripheral end of the crank rotor 14.

Furthermore, an 02 sensor 17 is placed facing the exhaust pipe I6 that communicates with the exhaust port 2b of the cylinder head 2. In addition, the code|symbol 18 is a catalytic converter.

On the other hand, reference numeral 20 is a control device consisting of a microcomputer or the like, and includes a CPU 21 . ROM22. RAM23.
and I10 interface 24 are connected to each other via a pass line 25. Each of the sensors 9a, 11 is connected to the input port of the I10 interface 24.
．． 15.17. An idle switch 9b and a battery power supply voltage terminal VB are connected, and an injector IO is connected to the output port via a drive circuit 26.

The ROM 22 contains a control program and an intake air amount map MP0. Throttle opening correction amount map M P
Fixed data such as KTH is stored, and the RAM 23 also stores data obtained by processing output signals from the sensors, switches, etc., and data processed by the CPU 21.

The CPU 21 calculates the fuel injection amount based on the data stored in the RAM 23 according to the control program stored in the ROM 22, and sends a drive pulse signal corresponding to the fuel injection amount at a predetermined timing synchronized with the engine rotation. It is output to the injector 10 via the drive circuit 2B.

The control device 20 performs fuel injection control functions such as throttle valve opening change rate calculation means Ml, throttle valve opening correction amount setting means M2. Correction throttle valve opening calculation means M3. Intake air amount estimation means M4. Fuel injection amount calculation means M5. Each function of the drive pulse signal output means M6 is realized.

The throttle valve opening change rate calculation means Ml reads the throttle valve opening θ detected by the throttle opening sensor 9a at predetermined time intervals, and calculates the throttle valve opening θ.
The opening change rate THv of a is THv-d(θNEW-θo
to )/dt.

Here, θN! ! W is the throttle valve opening degree read this time, and θOLD is the throttle valve opening degree read last time.

The throttle valve opening correction amount setting means M2 uses the engine rotational speed N calculated based on the output signal of the crank angle sensor 15 and the throttle valve opening change rate THv as parameters to create a throttle valve opening correction amount map MP. , the throttle valve opening correction amount KTH is set from H.

The above throttle valve opening correction amount map M P KT□
As shown in FIG. 4, a throttle valve opening correction amount KTI+ is stored using the throttle valve change speed THv and engine speed N as parameters, and R
It is stored as a map in a series of predetermined addresses in the OM 22.

The throttle opening correction amount KT□, which is stored in advance in the throttle opening correction amount map MPKTH, is the throttle opening correction amount KT□, which is the throttle opening correction amount KT□, which is the throttle opening correction amount KT□, which allows the actual in-cylinder intake air amount to be obtained during the intake stroke at the opening change rate THv of the throttle valve 5a during transition.
A value determined in advance through experiments or the like is used so that the opening of the throttle valve 5a is corrected to the opening.

That is, as shown in FIG. 3(a), the opening degree θ of the throttle valve 5a. In a transient state in which the throttle valve 5a is opened to an opening degree θ7 from the state shown in FIG.
The throttle valve opening at which the target in-cylinder intake air amount is obtained at time t0 when the opening change of a is started is THo. This throttle valve opening TH, is the throttle valve 5
Time t when the opening degree of a starts changing. earlier t. -3, and a phase difference γ (-1°-to-+) occurs here, and the intake air amount delay due to the zero difference γ during transient operation is converted into the throttle valve opening correction amount. , H.

The corrected throttle valve opening calculation means M3 calculates the corrected throttle valve opening TH from the current throttle opening θNEW and the throttle opening correction amount KT by the following calculation: TH−θNEW+KTH. Therefore, time t. Then, the corrected throttle valve opening pure white means M3 is THO-θ. To +,
,.

Therefore, time t. The corrected throttle valve opening THo is calculated.

The intake air amount estimating means M4 estimates the intake air amount Q from the intake air amount map MPQ using the corrected throttle valve opening TH and the engine speed N as parameters.

The intake air amount map MP0 is based on the throttle valve opening θ(
Using the corrected throttle valve opening TH) and engine speed N as parameters, the relationship between these values and the intake air amount Q is determined in advance theoretically or experimentally, and this is stored as the intake air amount Q. This address map is stored in the ROM 22 as a series of predetermined address maps.

The fuel injection amount calculation means M5 calculates the basic fuel injection ζTp from the engine rotational speed N and the estimated intake air amount Q by T p - K The fuel injection amount TI is calculated by Ti6-TpXCOEFxα+Ts.

In addition, C0EF is a cooling water temperature correction, an after-idle increase correction,
It is a correction coefficient for various increases related to full-open increase correction, etc., and α
is an air-fuel ratio feedback correction coefficient based on the output of the 02 sensor 17, and Ts is a voltage correction coefficient that interpolates the invalid injection time of the injector IO based on the battery terminal voltage.

The drive pulse signal output means M6 outputs a drive pulse signal corresponding to the calculated fuel injection amount Ti to the injector 1 of the corresponding cylinder at a predetermined timing synchronized with the engine speed N.
Output to 0.

In this way, the control device 20 determines the opening change rate THv of the throttle valve 5a, and uses the determined throttle valve opening change rate THv and the engine speed N to compensate for the delay in intake air amount due to the phase difference γ. The corrected throttle valve opening TH of the throttle valve 5a is calculated, and the fuel injection amount Ti is calculated based on the corrected throttle valve opening TH.
Set.

Next, the operation of the embodiment with the above configuration will be explained.

FIG. 5 is a flowchart showing a procedure for calculating the rate of change in throttle valve opening, and is a program that is executed by interruption at predetermined time intervals.

First, in step 5IOI, the throttle opening sensor 9a
Current throttle valve opening θNE based on the output signal of
W is read, and in step 5102, throttle valve opening data θ set in the previous routine. The LD is read from a predetermined address in the RAM 23.

Next, in step 5103, the current throttle valve opening θNEII' and the previous throttle valve opening θOL are calculated.
Calculate the throttle valve opening change rate THv based on D (THv-d(θN--〇〇LD)/di)
.

Then, in step Sl 04, the previous throttle valve opening degree θ is stored at a predetermined address in the RAM 2g. 1
D is updated with the current throttle valve opening degree θN, :w read in step 5101 above, and the routine exits.

On the other hand, FIG. 6 is a flowchart showing a fuel injection control procedure, which is controlled in a time-sharing manner with the above-mentioned throttle valve opening change rate calculation procedure.

First, in step S2 old, the engine rotation speed N is calculated based on the output signal of the crank angle sensor I5, and the throttle valve opening change rate THv is read out.

Next, in step 5202, the throttle valve opening correction amount KTo is set from □□ in the throttle valve opening correction amount map MP based on the engine speed N and the throttle valve opening change rate THv, and in step 5203, the throttle valve opening correction amount KTo is set from □□. The current throttle valve opening degree θNull based on the output signal of the degree sensor 9a is read, and the throttle valve opening degree correction amount KTFI and the current throttle valve opening degree θ are read.
The corrected throttle valve opening TH is calculated from NEW (TH-θNEW +Kt++).

Next, in step 5204, the intake air amount Q is estimated by searching the intake air amount map based on the corrected throttle valve opening TH and the engine speed N, and in step 5205, the intake air amount estimated as the engine speed N is calculated. Calculate the basic fuel injection amount Tp from Q (T p −K
/N).

Next, in step 8206, various increase correction coefficients C0EF related to cooling water temperature correction, post-idling increase correction, full-throttle increase correction, etc., air-fuel ratio feedback correction coefficient α based on the output of the 02 sensor 17, and injector 10 based on the battery terminal voltage are determined. The voltage correction coefficient Ts for interpolating the invalid injection time is set respectively, and the basic fuel injection amount Tp is corrected to calculate the fuel injection amount Ti (T1-TpXCO
EF ×a+Ts).

Then, in step 5207, a drive pulse signal corresponding to the fuel injection amount Ti is outputted to the injector IO of the corresponding cylinder at a predetermined timing, and fuel injection is executed.

The above operation is repeated, and the fuel injection amount Ti is set using the intake air amount Q estimated based on the throttle valve M degree TH with the opening degree θ of the throttle valve 5a corrected. Fuel is injected from IO.

Therefore, the cylinder intake air amount is corrected and determined as shown by the - dotted chain line in Fig. 3(b), and approximately approximates the target cylinder intake air amount shown by the solid line, and as shown in Fig. 3(C). - As shown by the dotted chain line, the change in the air-fuel ratio during transient periods is small, and a stable air-fuel ratio can be obtained.

In the embodiment described above, the throttle valve opening change rate THv of the throttle valve 5a is determined, the throttle valve opening correction amount KTI+ is determined from this, and the corrected throttle valve opening TH is further determined from the throttle valve opening correction amount KTH.
The intake air amount Q is estimated by calculating the
The present invention is not limited to this, but for example, the relationship between the throttle valve opening change rate factor Hv, the engine speed N, the throttle valve opening θ, and the intake air amount Q may be determined in advance and stored in the ROM 22 as a map. Then, R can be directly calculated from the throttle valve opening change rate THv, engine speed N, and throttle valve opening θ obtained at predetermined intervals.
The intake air amount Q may be read from the OM map.

〔Effect of the invention〕

As described above, according to the present invention, the speed of change in the opening of the throttle valve is determined from the opening of the throttle valve during a transient period obtained from the throttle valve opening detection means, and the speed of change in the opening of the throttle valve obtained is Since the throttle valve opening is corrected based on the throttle valve opening and the fuel injection amount is determined based on the corrected throttle valve opening and engine speed, it is possible to compensate for the delay in intake air amount due to the throttle valve phase difference during transient times. .

Furthermore, an appropriate air-fuel ratio can be obtained during a transient period, and drivability can be improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram (diagram corresponding to claims) showing the basic configuration of the present invention, Figs. 2 to 6 show an embodiment of the present invention, Fig. 2 is a schematic diagram of the engine control system, and Fig. 3 is a schematic diagram of the engine control system. is a characteristic diagram showing the throttle valve opening, intake air amount, and air-fuel ratio state during transient times, FIG. 4 is an explanatory diagram of the throttle opening correction amount map, and FIG. 5 is a flowchart showing the procedure for calculating the speed of change in throttle opening. , FIG. 6 is a flowchart showing the fuel injection control procedure, and FIG. 7 is an explanatory diagram of changes in intake air during a transient period. Ml... Throttle valve opening change speed calculation means M2
...Throttle valve opening correction amount setting means M3...
Correction throttle valve opening calculation means M4...Intake air amount estimation means M5...Fuel injection amount calculation means M6...Drive pulse signal output means 9a...Throttle opening sensor (throttle valve opening detection means)

Claims (1)

[Claims] Opening degree detection means for detecting the opening degree of the throttle valve;
and an engine rotation speed detection means for detecting the engine rotation speed, estimates the intake air amount from the throttle valve opening degree and the engine rotation speed, and sets the fuel injection amount based on the intake air amount and the engine rotation speed. In a fuel injection control device for an internal combustion engine, a throttle valve opening change rate calculating means for calculating a throttle valve opening change rate from a throttle valve opening change rate; Throttle valve opening correction amount setting means for setting an opening correction amount;
a corrected throttle valve opening calculation means for calculating a corrected throttle valve opening by correcting the throttle valve opening by the throttle valve opening correction amount; An intake air amount estimating means for estimating an intake air amount, a fuel injection amount calculation means for calculating a fuel injection amount based on the estimated intake air amount and the engine rotation speed, and a drive pulse signal corresponding to the calculated fuel injection amount for engine rotation. 1. A fuel injection control device for an internal combustion engine, comprising drive pulse signal output means for outputting a drive pulse signal to an injector at a predetermined timing synchronized with.