JPS6022033A - Air-fuel ratio controlling method for internal- combustion engine - Google Patents

Abstract

PURPOSE:To improve driving performance of an engine, by varying the fuel correction value for transient operation of the engine according to the deviation of the air-fuel ratio from the optimum air-fuel ratio at the time of accelerating of decelerating the engine in correcting the fuel supply rate by said fuel correction value according to the accelerating or decelerating conditions of the engine. CONSTITUTION:In operation of an engine, a control circuit CONT calculates the basic fuel quantity from the output signals of a means 2 for detecting the quantity of intake air, an engine-speed sensor 3 and a water-temperature sensor 4, corrects the basic fuel quantity in response to the output of an air-fuel ratio sensor 6, and controls a fuel injection valve 8 according to the corrected fuel quantity. Further, at the time of accelerating and decelerating the engine, the fuel quantity is corrected according to the fuel correction value for transient operation of the engine. Here, deviation of the air-fuel ratio from the optimum air-fuel ratio at the time of accelerating or decelerating the engine is detected and the fuel correction value for the transient operation of the engine is varied according to the detected deviation of the air-fuel ratio. By employing such a method, it is enabled to improve the driving performance of an engine by preventing deviation of the air-fuel ratio of mixture gas from the optimum air-fuel ratio at the time of accelerating or decelerating the engine.

Description

[Detailed description of the invention] Technical field The present invention is inspired by a method for controlling the air-fuel ratio of an internal combustion engine U.

The method according to Undiscovered and Akira is applied to an automatic squad engine.

BACKGROUND OF THE INVENTION One type of kettle fuel ratio control device for engines is known in the prior art. This type of device is a basic system that represents the jij,H fuel demand of the engine in steady state conditions by adjusting the values of predetermined engine operating parameters, including the engine temperature, which represents the engine's fuel demand. means for generating a fuel signal; means for detecting a transient engine piIJ operating state representative of a power increase request; Succeed, move, and lower the engine temperature
'): equal to the first value determined by and the first jj, ll determined by the detected engine transient
means for generating a reinforcement promoting signal having a value of 1 and increasing by a factor varying towards 1 determined by engine humidity; means for supplying fuel and thereby supplying fuel to the engine on demand during both steady state and transient conditions of the engine. This device provides a fuel supply system that always ensures the optimum air-fuel ratio not only in the steady state of the engine but also in the transient L-low state and obtains the optimum operation of the engine (for example, see Japanese Patent Application Laid-Open No. 56-6054). .

In the above-mentioned type of device, changes in the engine over time, such as changes in characteristics due to deposits attached to the injector nozzle during pulp clearance and EF work, deposits attached to the back surface of the cylinder intake valve, etc.
Changes in characteristics due to sticky substances such as coal particles derived from distilled oil components and combustion products, and changes in characteristics caused by JDI-induced changes due to variations in gasoline behavior, etc., are not taken into account, and these engines Since there is no means to detect changes in the air-fuel ratio from the optimum value during acceleration due to changes in the air-fuel ratio over time or changes in the properties of gasoline, gasoline with poor volatility may be used, or the mixture gas may be diluted due to changes in the engine over time. This may cause deterioration in drivability such as sluggishness during acceleration due to 411 (411) (conversely, if high-emission gasoline is used, the mixed gas will become richer during acceleration, resulting in poor fuel efficiency, poor emissions, and poor performance). There was a hint that it was a possibility.

Figure 1 shows the fluctuation of the air-fuel ratio in this case, especially the opening operation when deposits are attached to the back surface of the intake valve.
It has been F. The first is [, where A/F (0) is deposit attached riiJ (1), and A/F (DEP) is deposit.

The changes in the air-fuel ratio after the adhesion are shown below.

AOO is the acceleration point, DFjO is i, the speed point at °6,
A/F (OPT) indicates the optimum fuel ratio, A/F (LN) indicates the lean fuel ratio, and A/F (ROH) indicates the rich fuel ratio.

In addition, clogging of the injector can be corrected by feedback from the air-fuel ratio sensor in steady state, but this causes problems during acceleration and deceleration because there is no correction means. Further, similar problems have also occurred due to variations in manufacturing of the engine and air flow meter and changes over time.

Furthermore, the gasoline used in internal combustion engines is generally commercially available from the same manufacturer with different special characteristics such as summer and winter gasoline for all four seasons. Reed vapor pressure and distillation characteristics are generally well-known numerical values that indicate the volatility of gasoline, but when we look at the gasoline properties of various manufacturers, the Reid vapor pressure is 0.5 kff/Cd to 0.86 k.
! ,/dL Also, the grade of 10% distillate varies from 40 to 58 tr, and the J'li
Due to developmental changes, 'r? Air fuel ratio at '5 crossing! 1) Gender changes greatly. In the conventional system, no consideration is given to air-fuel ratio fluctuations caused by changes in volatility due to variations in gasoline properties.

Therefore, since there is no means for optimizing the air-fuel ratio during GJ1 acceleration/deceleration in the above-mentioned type of device, there is a risk of aging of the engine such as deposits and the use of gasoline with poor volatility. In this case, when applying force,
The air-fuel ratio becomes lean, causing deterioration in drivability such as sluggishness, and during deceleration, the air-fuel ratio becomes richer, leading to worsening of emissions and fuel efficiency.

OBJECTS OF THE INVENTION In view of the problems with the conventional type described above, the main object of the present invention is to correct the amount of correction in transient fuel correction so as to compensate for the air-fuel ratio deviation from the fii air-fuel ratio determined by detecting the air/fuel ratio deviation. Based on the idea of adjusting the i? of the mixed gas during acceleration and deceleration, due to deposits on the back of the intake valve, clogging of the injector, and changes over time in the engine and intake air conditioner detection device. The purpose is to prevent dilution of the air-fuel ratio at the time of acceleration r51j by preventing deviation from the tyM air-fuel ratio, and to improve drivability while preventing deterioration of emissions and fuel efficiency.

In addition, the present invention is capable of reducing the deviation of the air-fuel ratio from the optimum air-fuel ratio of the mixed gas at time y due to not only changes over time but also differences in gasoline properties, irregularities during engine manufacturing, and variations in air flow meter manufacturing. Ancillary purpose is to prevent.

Structure of the Invention In the present invention, the transient fuel correction amount t is determined at predetermined intervals according to the acceleration/deceleration state of the internal combustion engine, and the amount of fuel supplied to the internal combustion engine is determined by this correction amount. In performing the correction, the air-fuel ratio deviation from the optimum air-fuel ratio during the fluctuation of the internal combustion (51st 9J) is detected, and the correction amount of the transient fuel correction is adjusted in accordance with the detected air-fuel ratio deviation. An air-fuel ratio control method for an internal combustion engine is provided.

Embodiment An apparatus for performing an air-fuel ratio control method for an internal combustion engine as an embodiment of the present invention is shown in FIG. The configuration of the control circuit in the device shown in FIG. 2 is shown in FIG.

In the device shown in FIG. 2, 1 is a known electronically controlled fuel injection 6-cylinder spark ignition engine that is the power source of the automobile, 2 is a known intake thrust amount detection device that detects the amount of air taken into the engine 1, Reference numeral 6 denotes a known speed sensor for detecting the rotation speed of the engine 1, 4 a known water temperature sensor for measuring the cooling water temperature of the engine 1, 5 an exhaust passage for the engine 1, 6
is a known rough;i:1i ratio sensor provided in the exhaust passage 5.

7 is 1.1 of engine 1. Air intake 1 (゛, 8ζ
is inhaled into engine 1 ζ・! A throttle valve that controls air (, (), 9Nj, a well-known throttle sensor that detects the rise of throttle valve 9, and C0IJT calculates the amount of fuel to be supplied to engine 1 (J!; This is a control circuit that operates 8.

When the engine is in a steady state, the amount of fuel supplied to the engine 1 is determined by the control circuit 00NT based on the detection signals of the intake air amount detection device 2, the number of revolutions per minute sensor 3, and the water temperature sensor 4. ;, v h quantity, and more? The feedback fftt correct amount obtained from the signal of the L fuel ratio sensor 6 is corrected and determined as the valve opening time of the fuel 1:12 injection valve 8.

In addition, the control circuit 0ONT performs a transient fuel correction on PI' M when the throttle sensor 91 or the intake air m detector 2 detects the adjustment of the engine 1. It has withered away.

As shown in FIG. 6, the control circuit c ON T Ca
t, an input system and a multiplexer 101 which receives signals from the intake air amount sensor 2 and the water temperature sensor 4; an AD converter 102; a shaping circuit 106 which receives the signal from the air-fuel ratio sensor 6; a signal from the shaping circuit and the throttle sensor 91; It has an input boat 104 that receives a signal from the rotation sensor 6, and an input counter 105 that receives a signal from the rotation sensor 6. The control circuit also
Bus 106, ROM107.0PU10'8, RAM
109 , an output counter 110 , and a power driver 111 . The output of the power drive unit 111 is
” is supplied to valve 8.

As the control circuit 0ONT, a microcomputer type one can be used, for example, a Toyota TOOS type one can be used. In the control circuit 0ONT,
Air-fuel ratio deviation, output mode function and transient fuel correction function have been added.

Air-fuel ratio single action during acceleration/deceleration, that is, air-fuel ratio rare l (7) from the optimum air-fuel ratio A/F (OFT) during acceleration and each maximum deviation value D (A/F (LN)) to the rich side
, D(A/F(ROH)), and the single-acting air-fuel ratio sensor during acceleration/deceleration, that is, the air-fuel ratio sensor 6 during acceleration/deceleration detects the leanness and richness of the mixed gas 11S? The relationship between lean time during acceleration, T (1, IN) during acceleration and rich continuation time T (ROH) during deceleration is shown in the waveform diagram of FIG. 4 and the characteristic diagram of FIG. 5. In FIG. 4, A and OO represent acceleration, DEC represents deceleration, and 5 (6) represents the air-fuel ratio sensor signal.

As an example of the deviation of the fuel-fuel ratio from the optimum air-fuel ratio, the amount of deposits attached to the intake system W (, DF!P) and the maximum deviation of the air-fuel ratio at the time of adjustment D (A/F (LN)), D (A/
F(ROH))'s J section is shown in Figs. 6 and 7. From Figs. 4 to 7, lean jl'!ia during acceleration
By determining the EM time TL or the deceleration rich 8K kpja time TR as 111j, it can be seen that the value corresponding to the amount with deposit or the detection angle ttl: is. In addition, the 4th to 71st
For the d...J examination of the data in No. 1, a 5M-G type engine manufactured by Toyota Motor Corporation was used.

Control circuit 0. A schematic flowchart of the ONT control program is shown in FIG. This program is for performing electronically controlled fuel injection, and includes steps 5100 to 5.
It consists of 108 pieces. Start at 5100, 510
In step 1, memory and input/output ports are initialized.

5102, basic (,:9
Calculate the amount of fuel injection. In 5103, Ii,'? of the air-fuel ratio sensor 6? Beg.

Using this, feedback control is performed to correct the basic fuel injection amount so that the air-fuel ratio remains constant.

At 5104, the air-fuel ratio deviation during acceleration is detected, and at 5105
Then, from time to time, we will perform the operation XX of the mili correction ratio.

At 8106, one revolution of the engine is determined, and for every one revolution of the engine, at 8107, the opening time of the fuel scream control valve 8 is determined by the basic fuel 'j-' corrected by feedback control.
Calculate from i, l and the transient 113 combustion i:4 correction ratio,
At 5108, fuel 1 compensation injection valve control is performed. A detailed flowchart of the air-fuel ratio deviation setting process in the flowchart of FIG. 8 is shown in FIG. 9, and a detailed flowchart of the transient fuel judgment correction is shown in FIG.

In the air-fuel ratio deviation detection process shown in FIG.
As shown in the figure, processing is performed at fixed intervals (for example, 32.7 m5). As a method of detecting the total fuel ratio i'li6 difference, the output 1. of the air-fuel ratio sensor 6 is used. By comparing the voltage level with a constant voltage level, the two values of the mixed gas γ, <4 (!J-n)-like j (jH4) and the rich-type :')' A method is used to measure the li time LN) and the rich time T(ROM).

For example, with a deposit; i: f's t hunting' is cooling water f!
+4 occurs only at low temperatures, and in order to make it easier to estimate the deposit, 5202.5206.5204, cooling water temperature 80C, within 5 seconds after heating, engine rotation '13i900rTi~2D 00rIllIl In the case of lean 8 flj Tadasuji time T (LN), rich 1
1: Determine elapsed time T (ROH) #ii. In addition, rich and lean appear alternately at i and l2.5205, which is limited to the feedback system III.

In step 5206, it is determined whether it is rich or lean. For Lean 5
At 207, the lean time counter is incremented by 1 and T(
LN) for 32.7ms single (!Total with I4), ((.

Next, at 8208, the value of the time counter is constant (f
! (Rich Time Limit) is judged, and if it is exceeded, the rich correction counter is increased by 1 at 5209.
do. Next, in step 5210, the rich time counter is set to 0. If it is determined to be rich with 5206, similarly 8
In steps 211 to 5214, the rich time counter is increased by 1 and lean time is determined.

[) Deposit adhesion and peeling can be estimated from the values of the lean correction counter and rich correction counter determined in steps 5206 to 5214 described in IJ. That is, it is possible to estimate a change in the engine from a normal state to an abnormal state and a return from an abnormal state to a normal state.

In the transient fuel correction shown in FIG. 10, at 5601, the engine 1
Calculate the amount of intake air per revolution Q/N. At 5602, a determination is made to perform the following process at a fixed interval, for example, every 32.7 ms.

Correction coefficient Oa and smoothing coefficient Cb at S00B
Let be a function of the rich correction counter and the lean correction counter. In other words, the correction coefficient Oa% and the smoothing coefficient ab are taken as values corresponding to the air-fuel ratio (j, M difference) during acceleration.

In 5504, Q/N was smoothed (ct/w
) Find i from the following formula.

(Q/N) i = (Q/N) i-1+ (Q/N
-(Q/N) 1-1)/ab However, let (q/It calculated 32.7 ms ago be (Q/N)t-1.

In 5605, the ct/N, (Q/N) i ,
The transient fuel correction ratio f (AEe) is calculated using the following equation based on the value determined by aa % and the cooling water temperature.

f (AEW) = (Q/N - (Q, /N) i
) X0aXK where K is i for engine cooling
'flj is a direct ratio and is stored in the map in advance. Also/
(AKW) takes both positive and negative values depending on changes in Q and /H. Correction is performed by changing the transient fuel correction ratio f(AEW) to the basic fuel j'+(.

Therefore, as shown in FIG.
) The Q/N value also increases, (3) the (Q/N)z value also gradually increases, and (4) the transient fuel correction ratio f (4gw).
(5) The fuel injection valve opening time U is determined and fuel is supplied.

Also, if (6) the throttle is closed to decelerate, (7)
The Q/N value decreases, (8) the (Q/N)z value also gradually decreases, and (9) the transient fuel f1 correction ratio f (AEw) decreases with a waveform as shown in the diagram. (10) The fuel injection valve opening time U is determined and fuel is supplied.

An example of the operation results of the device in FIG.
is shown. In FIG. 12 (A>, (B)), the engine speed was set to 1[100 yen], and the cooling water temperature was set to 51]tZ'.

Acceleration is performed by throttle operation, and the acceleration condition is intake pressure 1
--401--4O0 while intake pressure J-100+nm H
It was assumed that there was a sudden rise to g J. (A) shows the air-fuel ratio versus time when gasoline A is used.

(B) shows the situation of the air-fuel ratio with respect to time when gasoline B is used, and shows the situation as a result of the control performed by the device shown in FIG.

As shown in Figures 12 (A) and (B), the air-fuel ratio during acceleration is approximately F: suitable nitrogen for gasoline A (10% distillation temperature 47c, Reid vapor pressure 0.72 k!, /cnl). The fuel ratio was the same, but the gasoline properties were yl-, and gasoline B (10% distillation temperature 54C1 lead vapor 0) had poor combustion performance.
．． 6ky/m), the air-fuel ratio during acceleration is rare)
Although it becomes 117, Fig. 2: In the position i, learning j + i
As a result, it becomes possible to obtain the same sudden fuel ratio characteristics at night as when gasoline A is used for about the seventh time. This 1:
[1゛脣1:1 It goes without saying that if you increase the positive amount, you can achieve Gakuchu in even fewer times.

In implementing the present invention, it is possible to take various modifications other than the above-mentioned practical example. For example, in the above embodiment, as shown in step 5302, the calculation of (Q/N)i is performed for a fixed period of 116 (32,7 m
5), but instead, as shown in the flowchart of FIG. 13, it is also possible to synchronize the total S> of (Q/N)i with the engine rotation and perform it, for example, every engine 11i14W.

In the figure S13, 5401 calculates o, /N, and 54D2 determines each rotation of the engine? Yes.

In 5403, correction coefficient % Oa and smoothing coefficient MOb
Let be a function of the rich correction counter and the lean 4)11 positive counter. In other words, the correction coefficient Oa, the smoothing coefficient o
Let b be a value corresponding to the air-fuel ratio deviation during acceleration.

In 5404, Q/N was smoothed (Q/n
>) from the following formula.

(Q/N,))-(Q/N)'-1+ (Q/N-(Q
/N)ノ'-1)/cbノHowever, the engine was ignited once before the FA.C Q/
W )) is (Q/N) No 1.

5405) +xj tIselfQ/L (Q/'
))'t Based on the value determined by Ca1 and cooling water temperature,
The transient air-fuel ratio correction ratio f' (Axw) is calculated using the following equation.

f'(Aiw) −(Q/N−(Q/N )))x C
aXIζ'Correction is performed by multiplying the basic fuel amount by this f'(AFliW).

By setting the above (Q/IJ >) in synchronization with the engine rotation, the combustion cycle of the engine in which the increase and decrease due to the transient air-fuel ratio n11 direct ratio f' (AmW) contributes is the same regardless of the engine rotation speed. They are almost the same under acceleration conditions. Therefore, it is possible to prevent the air-fuel ratio from fluctuating during transient periods under various engine conditions.

In addition, in the above-mentioned actual MLi example, the air-fuel ratio (:, jf r, i'52 tJ, 't is constant at 5206 for 5 seconds after acceleration, and this can be seen from Figures 4 and 5. As in, T(LN) and T(ROH) at 4 o'clock are 1
Even if i(ll) is determined, i/jmi can be produced.

Furthermore, in the above-mentioned embodiment, an increase of 1 is performed based on the intake air amount Q/N and its smoothing amount as the determining factor for the correction 172, but this is based on the intake air amount Q/N and its smoothing amount.
Throttle l;jJ degree LIi and its namesha G
)11. Subsequently, a stomach test may be performed.

In addition, in the above embodiment, the amount is increased based on the difference between the ilh positive amount determining factor amount and the respective smoothing amount, but the bit positive, l+, 4: determining factor 'r+, L The difference between the current value and the previous value may be used.

Effects of the Invention According to the present invention, 7JII deceleration II♂[
By preventing deviation from the optimum air-fuel ratio of the 16 mixture gas, dilution of the air-fuel ratio during acceleration is prevented, and drivability can be improved while preventing deterioration of emissions and fuel efficiency.

4. Drawing 17ij, (Illustrated explanation) Fig. 1 is a waveform diagram showing air-fuel ratio behavior during acceleration and deceleration before and after deposit, Fig. 2 is an air-fuel ratio control method for an internal combustion engine as an embodiment of the present invention. Figure 6 is a diagram showing the formation of the five-turn section h!r in the equipment shown in Figure 2. Figures 4 and 5 are the air-fuel ratio behavior during acceleration/deceleration and the The waveforms (S) and characteristic diagrams showing the relationship between fuel ratio behavior and characteristic diagrams, Figures 6 and 7, show the relationship between the amount of deposits attached to the intake system and the adjustment Fig. 8 does not show the flow of performance in the device shown in Fig. 2.
Figure 9 is a flowchart showing the details of the deposit amount corresponding value detection calculation, Figure 10 is a flowchart showing the transient fuel consumption correction EP K11l, and No. 111'J+ is the flowchart showing the fuel consumption at the time of depletion. 12(A) and 12(B) are diagrams showing an example of the operation results of the apparatus shown in FIG. It is a calculation flowchart shown.

(Explanation of symbols) 1...Engine, 2...Intake air detection equipment f
-, 3... Rotation speed sensor, 4... Water humidity sensor, 5.
...j non-air passage, 6... air-fuel ratio sensor, 7... suction %
Tetsu, 8... Compensation J,; 1.1 injection J1-9... Throttle valve, 91... Throttle sensor, 0ONT...
control circuit.

Hatake 4 Figure 6 )7 Figure W(DEP) Funeral diagram 8 Figure 11 Figure 12 case 13 figure Continuation of page 1 0 shots clear person Kunihiko Sato Toyota Type Toyota Town No. 1 Toyota Motor Corporation Inside Dosha Co., Ltd. ■Applicant: Toyota Motor Corporation 1 Toyotacho, Toyota City

Claims (1)

[Claims] 1. In determining the transient fuel correction value at predetermined intervals according to the acceleration/deceleration state of the internal combustion engine and correcting the amount of fuel supplied to the internal combustion engine with this correction amount, Detects the air-fuel ratio deviation from the optimum air-fuel ratio during acceleration and deceleration of the internal combustion engine, and uses the detected air-fuel ratio deviation! An air-fuel ratio control method for an internal combustion engine, the method comprising adjusting the amount of transient fuel correction accordingly. 2. The method according to claim 1, wherein the transient fuel correction is a transient fuel correction that determines a transient fuel correction amount every predetermined period of time. Otsu. The transient fuel correction is based on the internal combustion 11. 2. The method according to claim 1, wherein the transient fuel correction amount is determined in synchronization with the rotation of the leapfrog. 4. The method according to claim 1, wherein the transient fuel li positive is a transient fuel-specific correction using intake air h1 as a correction amount determining factor. 5. The method according to claim 1, wherein the transient fuel correction is an over-gamma reaction fuel correction using throttle opening or intake pipe pressure as a correction amount determining factor. 6. The method according to any one of claims 1 to 9, wherein the air-fuel ratio deviation detection is performed using an air-fuel ratio sensor. Z. The method according to claim 1, wherein the air-fuel ratio deviation is a fuel-to-fuel ratio deviation caused by deposits attached to the intake thread of the internal combustion engine μi4. 8. The air-fuel ratio deviation is the air-fuel ratio deviation caused by the first deposit attached to the nozzle part of the injector that supplies 1° of fuel to the internal combustion (82 flashes).
The method described in paragraph 1. 9. The air-fuel ratio deviation is an air-fuel ratio deviation resulting from variations in the production of the intake air star detection means II8 for detecting intake air to the internal combustion sensor or changes in characteristics due to changes over time. Item 1: 1 small method. 10. The method according to claim 1, wherein the air-fuel ratio deviation is an air-fuel ratio deviation resulting from manufacturing variations or changes over time of the internal combustion engine. 11. The method according to claim 1, wherein the air-fuel ratio deviation is an air-fuel ratio deviation resulting from variations or changes in the properties of the fuel used in the internal combustion. 12. The method according to claim 1, wherein the correction is a transient fuel correction in which the correction amount is determined from the correction amount determining factor amount and the annealing amount of this amount. 13. ii&+'+iJ correct The method according to claim 12, wherein the correction amount is determined by determining the amount of correction A1 based on the difference between the determining factor amount and the annealing factor.14. The method according to claim 12 or claim 16, wherein y is a smoothing calculation of the correction amount determining factor amount, which is a smoothing calculation of the amount that changes due to acceleration/deceleration at fixed time intervals. 15. The correction Quantity determining factor; The method according to claim 12 or claim 16, wherein the smoothing operation is 3γ.