JPS61258942A - Fuel injection controller for engine - Google Patents

Abstract

PURPOSE:To improve the acceleration performance and the exhaust gas purifying performance by providing means for deciding the transient state and means for correcting the actual basic fuel injection in accordance with transient state upon decision of transient state. CONSTITUTION:Basic fuel injection operating means 3 will operate the basic fuel injection Tp on the basis of intake air flow and engine rotation. Then basic fuel injection to be executed is operated through operating means 4 on the basis of said injection Tp. While transient state deciding means 6 will decide the transient state. Correcting means 7 will correct the executive basic fuel injection in accordance with transient state upon decision of transient state. Consequently, the acceleration performance at initial stage and the exhaust gas purifying performance at the initial stage of deceleration can be improved.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a fuel injection control device for an engine.

(Prior art) As one of electronically controlled fuel injection devices for spark ignition engines,
BACKGROUND OF THE INVENTION L-dinitronic fuel injection systems have been well known. This device basically calculates the basic fuel injection amount per stroke of the engine based on the intake air flow rate detected by the air 70-meter and the engine speed detected by the engine speed sensor. By outputting a pulse signal corresponding to the fuel injection amount to the fuel injection valve, the opening time of the fuel injection valve is controlled and the fuel injection amount is quantitatively controlled.

The air 70-meter used in this device is generally a flap type in which the Messeling plate is rotationally driven by the intake air flowing through the engine intake system. When there is no change, the air flow rate is detected with an error within a range that does not cause any practical problems, but when the air flow rate increases rapidly, such as during acceleration, the Messeling plate overshoots due to its own inertia. Detects an air flow rate that is considerably larger than the actual air flow rate.

For this reason, the calculated fuel injection amount deviates from the actually required fuel injection amount and becomes excessive, deteriorating the exhaust gas purification characteristics.

In addition, the overshoot phenomenon attenuates over time after acceleration, and the air flow rate detected by the air 70-meter approaches the air flow rate actually taken into the Schilling, and the calculated fuel injection amount is the amount of fuel actually required. approaches the injection amount.

At this time, if all of the fuel injected from the fuel injection valve is sucked into the Schilling, the mixture sucked into the Schilling will be a suitable mixture, but in reality, the fuel injected from the fuel injection valve is A part of it adheres to the wall surface of the intake pipe and forms a wall flow. As a result, until the amount of fuel adhering to the wall that forms a wall flow and is not sucked into the silling and the amount of fuel that flows into the silling due to this adhering to the wall become equal to each other, the amount of fuel supplied to the silling becomes insufficient and the mixture is mixed. The energy becomes weaker and the output decreases.

This causes a large acceleration shock in which the vehicle vibrates back and forth during acceleration, and also causes problems in terms of exhaust gas purification measures.

Therefore, devices have been proposed that avoid fluctuations in the air-fuel ratio caused by the overshoot phenomenon of the air 70-meter's Messing plate and that improve driveability, especially during acceleration (for example, Japanese Patent Laid-Open No. 58-8239 (see publication).

In this device, the execution basic fuel injection amount is determined by performing the following calculation based on the basic fuel injection amount calculated from the intake air flow rate and the rotational speed.

TPDMP+ = TPDMP + - 1 + (Tp - TPDMP + - 1) 1) In other words, the newly calculated basic fuel injection tTp and the previously calculated basic fuel injection amount TPDMP, -
, by increasing the weighting coefficient α (α〈1), is 1
Previously calculated execution basic fuel injection amount T P D MP
A weighted average is obtained by adding to +-1, and this weighted average is set as the current execution base/main fuel injection amount TPDMP.

As a result, even if 'rp changes rapidly due to overshoot of the air 70-meter meshing plate during engine acceleration, TPDMP changes relatively slowly, and α
If is set appropriately, the ratio of the flint basic fuel injection amount to the intake air flow rate per stroke of the engine will not change significantly, and overshoot during acceleration will be avoided.

(Problems to be Solved by the Invention) By the way, in the flap type air 70-meter, in addition to its own inertial response delay, l'l! There is a response delay due to mechanical friction, and in the dynamic characteristics of the air meter, the more rapid the change in the intake air flow rate, the wider the response delay (response delay becomes), and there is a response delay corresponding to a cycle due to calculation at a constant cycle.

For this reason, even the TPDMP+ cannot follow the change in the intake air flow rate flowing into the shilling at the initial stage of the transition, and i' P D M P I is shown in FIG. 8(A).

As shown by the broken line in FIG. 8(B), a response delay occurs with respect to the amount of fuel (1, alpha chain line) commensurate with the Schilling intake air flow rate. Note that FIG. 158(A) and FIG. 8(B) show the actual basic fuel injection amount characteristics during acceleration and deceleration, respectively.

As a result, even assuming that there is no fuel delay, TPD M
With P I, it is not possible to maintain the specified air-fuel ratio, and when accelerating, the mixture becomes leaner, making it impossible to obtain the desired acceleration performance. Also, when decelerating, the mixture becomes richer, and excess air-fuel mixture is supplied to the exhaust gas. This may lead to deterioration of the gas purification properties (.

Furthermore, in reality, when the intake air flow rate is detected, there is a fuel delay until the fuel injected from α is sucked into the combustion chamber, so when correcting the fuel injection amount during a transient period, T
F' l) M P The fuel delay is added to the response delay of r itself, resulting in a large deviation from the fuel amount commensurate with Schilling's intake air flow rate.

As a result, fluctuations in the air-fuel ratio at the initial stage of the transition become even larger, making the acceleration performance during acceleration and the exhaust gas purification characteristics during deceleration insufficient.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel injection control device that can control the air-fuel ratio to a predetermined value by determining a fuel injection amount commensurate with the cylinder intake air flow rate even in the early stage of a transient period.

(Means for Solving the Problems) FIG. 1 is an overall configuration diagram for clearly showing the configuration of the present invention.

Reference numeral 1 designates an intake air flow rate detection means such as an air 70-meter for detecting the intake air flow rate, and 2 designates a rotation speed detection means for detecting the engine rotation speed. Reference numeral 3 denotes a basic fuel injection amount calculation means, which calculates a basic fuel injection amount Tp at regular intervals based on these intake air flow rates and engine speed.

Reference numeral 4 denotes an effective basic fuel injection amount calculation means, which calculates an effective basic fuel injection amount based on the Tp using the following equation.

TPDMP+=(1-α)TPDMP+-+ 10aTp
TPDMPi: Execution basic fuel injection amount TPDMP, -1: Previous execution basic fuel injection amount Tp: Basic fuel injection amount α: Constant (0 × a × 1) 6 is a transient state The determining means determines transient states such as acceleration and deceleration. Reference numeral 7 denotes a correction means that corrects the executed basic fuel injection amount TPDMP+ in accordance with the transient state when the transient state is determined.

Reference numeral 5 denotes an injection valve driving means for driving the fuel injection valve to open based on the corrected basic fuel injection amount.

(Function) With this configuration, the transient state determining means 6
determines the transient time without causing a response delay, and upon receiving this signal, the correction means 7 calculates the execution basic fuel injection amount T P D M P calculated by the execution basic fuel injection amount calculation means 4.
Since I is corrected to calculate the amount of fuel commensurate with the cylinder intake air flow rate, a predetermined air-fuel ratio can be obtained even at the initial stage of the transition. 1. As a result, acceleration performance during acceleration can be improved, and exhaust gas purification characteristics during deceleration can be improved.

(Embodiment) FIG. 2 is a schematic diagram of a mechanical configuration of an embodiment of the present invention. In the figure, 10 is the engine body, 11 is the cylinder block,
12 is a combustion chamber, the intake system is an intake manifold 13,
Throttle body 14 in which throttle valve 14A is installed
, an intake tube 15. An air meter 70-meter 16 is installed in this intake system to detect the intake air flow rate. Additionally, the throttle body 14 includes a throttle valve 14A.
A throttle switch 27 for detecting the fully closed state of the throttle valve 14A and a throttle sensor 20 for detecting the opening degree of the throttle valve 14A are provided, and the throttle sensor 20 functions as a means for detecting a transient state.

On the other hand, the exhaust system consists of an exhaust manifold 17, an exhaust pipe 18, and a three-way catalytic converter 19, and the exhaust manifold 17 is provided with an oxygen sensor 28 for detecting the oxygen concentration in the exhaust gas.

Reference numeral 40 drives the fuel injection valve 29 provided in the intake manifold 13 to open based on the signals detected by these sensors.

FIG. 3 is a block diagram of the control unit 40. This example is applied to a device that performs fuel injection by electronic control, and the control is performed by the central fluid calculation unit (CPU).
) 41, read-on memory (ROM) 42, random access memory (RAM) 43, A/D converter with multiplexer 44, human powered interface 7 ace circuit 45 with par/7 memory, output interface 7 ace circuit 46
This is done centrally by a microcomputer consisting of .

A/D converter 44 of the snare control unit 40
The output signal from the air meter 16 outputs a signal corresponding to the air flow rate taken into the engine, the throttle signal from the throttle sensor 20 outputs a signal corresponding to the opening degree of the throttle valve 14A, and the cooling water temperature. a water temperature signal from the water temperature sensor 22 that detects the water temperature, an intake temperature signal generated by the intake temperature sensor 21 attached to the air 70-meter 16,
A voltage signal from the battery 23 that supplies power to the fuel injection valve 29 and the control 24) is inputted, and the input interface 7 ace circuit 45 is inputted to the distributor 24.
A reference position signal and a crank angle signal generated by the reference position sensor 25 and crank sensor 26 attached to the , a throttle fully closed signal generated by the throttle switch 27,
An oxygen concentration signal generated by the oxygen sensor 28 is input.

On the other hand, the CPU 41 calculates the fuel injection amount based on the data detected by each sensor according to the program stored in the ROM 42, and outputs a pulse signal having a pulse width corresponding to the calculated fuel injection amount to the interface. 7
It is output to the fuel injection valve 29 via the ace circuit 46.

Note that, as shown in FIG. 4, the air 70-meter 16 includes a case 31 provided with an intake passage 32, and a measuring plate rotatably supported by the case 31 by a pongee 33 and extending across the intake passage 32. 34, and a convening plate 36 which is integrally formed with the medial lift plate 34 and defines a gunbing chamber 35 on one side.
And the potentiometer that is drivingly connected to the shaft 33! meter 37, and the meshing plate 34 is connected to the intake passage 32.
The slider 38 of the potentiometer 37 is rotated counterclockwise in the figure to an angle where the force exerted by the intake airflow flowing through the inlet balances the spring force of a return spring (not shown).
By driving counterclockwise, the rotation angle of the measuring plate 34, that is, the intake air flow rate, can be adjusted to
The voltage ratio is converted to the voltage ratio QA of the meter 37.

The voltage ratio QA of the potentiometer 37 is between terminal Vs and terminal E.
If the voltage between the terminals Vc and E is Us, and the voltage between the terminals Vc and E is Ub, it is expressed as Q A = U s / U b, and the voltage Ub is constant as long as the supply voltage is constant. , the voltage US decreases as the slider 38 rotates counterclockwise. Therefore, the voltage ratio QA changes in inverse proportion to the intake air flow rate.

FIG. 5 is a flowchart showing the contents of the operations performed within the CPU 41 in FIG. Numbers indicate each step.

To explain the operation of this embodiment based on this flowchart, in 50.51, the voltage ratio QA obtained by A/D converting the voltage ratio signal from the air 70-meter 16 and the crank angle signal are obtained by counting for a predetermined period of time. Perform the following calculation from the engine rotation speed N, and set the basic fuel injection amount Tp to Tp=/NXQ
Calculate at A.

However, K is a constant.

This Tp is determined by the amount of fuel (1 point 114 I
IA), the air-fuel ratio shifts toward the lean side at the beginning of the transition, as shown in FIG. 7(C), and then shifts significantly toward the rich side. In addition, Fig. 7 (A) shows the fuel injection amount characteristics during acceleration.
FIG. 7(B) shows the error from the fuel amount corresponding to the cylinder intake air flow rate at that time, and FIG. 7(C) shows the deviation from the set air-fuel ratio.

In 52, execute basic fuel injection fl T P D M P
+ is calculated using the following formula.

TPDMP, = (1-α)TPDMP +-1
+αTpTPDMP+: Executed basic fuel injection amount TPDMP1. ．． , I: Previously calculated execution basic fuel injection amount Tp: Basic fuel injection amount α: Constant (0 × α<1) This formula is the same as the conventional example, and is a weighted average with α as a weighted average coefficient. It is.

Therefore, as shown in Figures 7 (A) to 7 (C), T P D M P I is much closer to the fuel amount corresponding to the cylinder intake air flow rate than Tp, but there is still an error in the initial stage of the transition. occurs, and the air-fuel ratio deviates from the set air-fuel ratio to the lean side.

This invention has been proposed in order to eliminate such fluctuations from the set air-fuel ratio at the initial stage of the transient, and detects the transient and corrects TPDMPl according to the degree of the transient. This is realized by determining the transient state at 54.56 and correcting T P D M P + at 55 and 57.58.

That is, at 53, the output THR of the throttle sensor 20
is A/D converted, and the change rate ΔTHR of this THR is calculated at 54.
It is determined whether or not it is in a transient state by comparing the value with a preset reference value. If ΔTHR is a positive value and exceeds the positive reference value, it is determined that it is accelerating and the 55
Proceed to. If ΔTHR is less than the positive reference value at 54, the process proceeds to 56, where it is compared with the negative reference value, and if it exceeds the negative reference value and is smaller, it is determined that deceleration is occurring, and the process proceeds to 57.

In 55, the acceleration correction coefficient ACC is determined as a function of ΔTHR from ACC=f(ΔTHR), and in 57, the deceleration correction coefficient DEC is determined as a function of ΔTHR, DEC=f(ΔTHR).
Find it from R). In addition, during steady operation, the correction coefficient ACC
, DEC are not calculated, and ACC and DEC are 0.

From these ACC and DEC, the fuel 11QAcYL corresponding to the amount of fuel corresponding to the Schilling intake air flow rate is determined using the following formula.

QACYL=(1+ACC-DEC) XTPDMP.

With this correction, QACYL is
), the error is even smaller than T P D M P + , and the air-fuel ratio approaches the set air-fuel ratio. In addition, Fig. 7 (C) shows QACYL with HO8 and without HO3. Although this case is shown, this HO8 will be described later.

As a result, even at the initial stage of the transition, the fuel amount is corrected to match the Schilling intake air flow rate, and the air-fuel ratio can be controlled to a predetermined air-fuel ratio. As a result, the air-fuel ratio fluctuates in the initial stage of the transition, and during acceleration, the desired acceleration performance cannot be obtained due to the dilution of the air-fuel mixture, and during deceleration, excess air-fuel mixture is supplied, which reduces the exhaust gas purification characteristics. It will no longer cause any deterioration.

59 to 66* are similar to the conventional example. At 59, the water temperature sensor 22. Various correction coefficients such as a warm-up correction coefficient necessary for correcting the fuel injection amount are calculated from data obtained from various sensors such as the intake air temperature sensor 21 (for example, cooling water temperature TW) (the sum of these correction coefficients is C0EF). ), 60,
Based on the signal generated by the oxygen sensor 28, an air-fuel ratio feedback correction coefficient ALPHA targeting the stoichiometric air-fuel ratio is determined. 61 is the fuel delay correction coefficient HO for fuel delay.
3 will be described later), and in step 62, the invalid injection amount Ts is determined from the battery voltage. In 63, the air-fuel mixture correction coefficient KMR is set so that the air-fuel ratio at 1 becomes the target air-fuel ratio.
seek.

At step 64, the required fuel injection amount Ti is determined using the following equation.

T i = Q A CY L X COE F X
A L P HAXHO8/KMR+Ts Although this injection amount calculation routine is explained as the injection amount, in reality, the fuel injection amount is determined by the pulse width of the pulse signal that drives the fuel injection valve 29 to open. ,
Ti corresponds to the pulse width. Therefore, a pulse signal having a pulse width of Ti is output to the fuel injection valve 29.

Finally, in 65, calculate the depreciation of ACC and DEC, and
6, the effective fuel injection amount T E N = T i T s
seek.

Next, the fuel delay correction coefficient HO8 calculated at 61 will be explained.

Air 70 by QACYL - Based on meter 16 <TPD
Although the response delay of MP+ itself is eliminated, there is actually a fuel delay, so it is necessary to further correct QACYL from this breath.

If all of the fuel injected from the fuel injection valve 29 is sucked into the Schilling, an appropriate air-fuel ratio can be obtained by calculating the air-fuel ratio of the mixture sucked into the Schilling based on QACYL. . However, in reality, a portion of the injected fuel adheres to the wall of the intake pipe to form a wall flow. For this reason, if the amount of fuel flowing into the shilling is Q fcyl, the total amount of wall flow is FwI, and the proportion of TEN that is directly sucked into the shilling as an airflow is d, the proportion of SFIII that flows into the shilling is g. Qfcyl and FwI are given by the following equations.

Q fcyl=dX T E N +gX F wH-
1Fw+ = (1-d)TEN+(1g)FwI-IF
wI heat: Add (Lg
is determined by gasoline components, cooling water temperature TW, intake air temperature TA, intake pipe pressure, etc.

Therefore, this Qfcyl is the required fuel fiQ A CY
In order to obtain L/KMR, the fuel delay correction coefficient is multiplied by HO8 (HO8>1) (Q A CY
L/KMR) XHO8 must be supplied from the fuel injection valve 29 in multiple ports as TEN.

Therefore, substitute Qfcyl=QACYL/KMR TEN=(QACYL/KMR)XHO8 into the formula of Qfcyl, and
When calculating for O3, the following formula is obtained.

HO3=(1-g-Fw+-1・KMR/QACYL)
x(1/d) However, the Kono formula calculates C0EF, AI, and PHA as 1°0.

By the way, in the conventional example, HO8 is calculated from this formula in order to correct the fuel delay, but in the conventional example, QACYL becomes T P D M P + in the formula for HO8.

So, considering the case where HO8 is calculated with TPDMP+, during acceleration, TPDMP is calculated to be smaller than Q A CY L for the amount of fuel corresponding to the Schilling intake air flow rate, so TPDMP is used. HO8 calculated using QACYL is smaller than HO8 calculated using QACYL.

Therefore, in addition to T P D M P I itself being read small, HO8 also becomes small, so even if fuel delay correction is performed, the value becomes extremely small compared to the required fuel amount.

Furthermore, during deceleration, a value larger than the required fuel amount is calculated, which is the opposite of when accelerating.

As a result, in the conventional example, the acceleration performance during acceleration is impaired1, and the exhaust gas purification characteristics during deceleration are still insufficient.

In contrast, in this example, the amount of fuel commensurate with the Schilling intake air flow rate is accurately determined as QACYL, and this QACY
When fuel delay correction is performed using
The air-fuel ratio can be brought closer to the set air-fuel ratio than (QACYL without HO8), and acceleration response and exhaust gas purification characteristics are further improved.

The specific calculation for HO8 is as shown in Figure 6. QACYL is 70 (approximately equivalent to intake pipe pressure, so QACYL is used instead of intake pipe pressure).
, TW, find g + d from TA, find Fl with Mushita 71,
In step 72, g*dtQAcYL, Fwll are determined, and HO8 is calculated by substituting these into the HOS equation.

In this embodiment, the flap type of the L noetronic type air 70-meter was described, but the invention is not limited to this. Hot wire type air 7
The present invention can be similarly applied to a 0-meter.

(Effects of the Invention) The present invention provides a basic fuel injection amount calculation means for calculating a basic fuel injection amount Tp at regular intervals based on an intake air flow rate and an engine speed, and an executed basic fuel injection amount based on the basic fuel injection amount Tp. TPDMP + = (1-α)TPDMP
+-1+crTp (TPDMPi-1: 1 time Bf (calculated basic fuel injection amount, α: constant (0 × α<1))
In a fuel injection control device for an engine, comprising an execution basic fuel injection ni calculation means for calculating the execution basic fuel injection amount, and an injection valve drive means for opening and driving the fuel injection valve based on the execution basic fuel injection amount,
A transient state determining means for determining a transient state, and when the transient state is determined, the execution basic fuel injection'! ! kTP
Since the correction means for correcting D M P + according to the transient state is provided, it is possible to accurately control the air-fuel ratio to a predetermined air-fuel ratio even in the early stage of the transient state, which improves acceleration performance at the early stage of acceleration. The exhaust gas at the initial stage of deceleration can improve the gas purification characteristics.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram for clearly showing the configuration of the present invention. FIG. 2 is a schematic diagram of the mechanical configuration of an embodiment of the present invention;
FIG. 3 is a block diagram of the mount roll unit, and FIG. 4 is a sectional view of the air 70-meter. FIG. 5 is a flow chart showing the operation contents performed in CPtJ41 in FIG. 3, FIG. 6 is a flow chart showing the fuel delay correction calculation, and FIG. 7 (A) shows the fuel injection amount characteristics during acceleration. 7
FIG. 7(B) is an explanatory diagram showing the error from the fuel amount commensurate with the Schilling intake air flow rate, and FIG. 7(C) is a diagram showing the deviation from the set air-fuel ratio in comparison with a conventional example. FIG. 8(A) and FIG. 8(B) are action theory FIR diagrams of the conventional example. 1...Air flow rate detection means, 2...Rotation speed detection means,
3... Basic fuel injection amount calculation means, 4... Execution basic fuel injection amount calculation means, 5... Injection valve driving means, 6...
Transient state determination means, 7... Auxiliary means, 10... Engine body, 12... Combustion chamber, 13... Intake manifold, 14A... Throttle valve, 16... Air 70-meter, 17... Exhaust manifold, 19... Three-way catalytic converter, 20... Throttle sensor, 21...
- Intake temperature sensor, 22...Water temperature sensor, 23...Battery, 24...Distributor, 25...Reference position sensor, 26...Crank angle sensor, 27...
・Throttle switch, 28...Oxygen sensor, 31・
...Case, 32...Intake passage, 33...Shaft, 34
...Measuring plate, 35...Gunbing chamber, 36...Compensation plate, 37
...Potency polishing meter, 38...Slider, 40.
...Control unit, 41...CPU, 42.
...ROM, 43...RAM, 44...A/D converter, 45...input interface 7 ace circuit, 46...
・Output interface 7 ace circuit. Patent Applicant Nissan Motor Co., Ltd. Figure 3 Figure 4 Figure 8 (A) 1 * Figure a (B) O-skewer] Procedural amendment (method) % formula % 1. Indication of case 1985 Patent Application No. 99145 No. 2, Name of the invention Engine fuel injection control device 3, Relationship with the case of the person making the amendment Patent applicant address Name of No. 2 Takaracho, Kanayō-ku, Yokohama-shi, Kanagawa Prefecture (3
99) Nissan Motor Co., Ltd. 4, Agent 5, Date of amendment order: July 10, 1985 (Shipping date: July 30, 1985)
6. Subject of correction
1. “Detailed Description of the Invention” column in the specification. 7. Contents of correction

Claims (1)

[Claims] A basic fuel injection amount calculating means for calculating a basic fuel injection amount Tp at regular intervals based on the intake air flow rate and engine speed, and an execution basic fuel injection amount TPDM based on the basic fuel injection amount Tp.
P_i=(1-α)TPDMP_i_-_1+αTp(
TPDMP_i_-_1: Execution basic fuel injection amount calculation means for calculating the execution basic fuel injection amount calculated one time previously, α: constant (0<α<1), and a fuel injection valve based on this execution basic fuel injection amount. In a fuel injection control device for an engine, the fuel injection control device for an engine includes an injection valve driving means for driving an opening of the valve, and a transient state determining means for determining a transient state, and the execution basic fuel injection amount TPDMP_i is changed to the transient state when the transient state is determined. 1. A fuel injection control device for an engine, comprising a correction means for correcting accordingly.