JPS6026132A - Air-fuel ratio controlling method in internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent an emission of exhaust and a rate of fuel consumption from worsening as well as to aim at improvements in drivability, by detecting an air-fuel ratio deviation from the setting air-fuel ratio in time of acceleration, while compensating a fuel increment value at acceleration according to the air- fuel ratio deviation. CONSTITUTION:In the case where a control circuit CONT performs a fuel injection in accordance with a control program, a fundamental fuel injection quantity is calculated, then feedback control for an air-fuel ratio sensor takes place, thus the fundamental fuel injection quantity is compensated. And, fuel increment at the initial acceleration and air-fuel deviation detection both take place, while air- fuel deviation compensation to the fuel increment at the initial acceleration takes place as well. With this constitution, a slip out of the optimum air-fuel ratio of mixed gas in time of acceleration is prevented from occurring, so that improvements in drivability are promoted while preventing emission of exhaust and rate of fuel consumption from worsening.

Description

[Detailed description of the invention] Technical field The present invention relates to an air-fuel ratio control method for an internal combustion engine.

The method according to the invention is applied to motor vehicle engines.

BACKGROUND OF THE INVENTION One type of air-fuel ratio control device for an engine is known in the prior art. This type of device includes means for generating a basic fuel signal representative of the fuel demand of the engine at steady state in response to the value of a predetermined engine operating temperature including engine temperature representative of the fuel demand of the engine; means for detecting a transient engine operating condition indicative of a demand; and in response to the measured engine temperature and the detected transient engine operating condition, a first barrier determined by the engine temperature; and means for generating a reinforcing boost signal, which has an initial value determined by the detected engine transient and is increased by a factor accelerating towards unity at a rate determined by the engine temperature;
means for supplying fuel to the engine in accordance with the base fuel signal and the reinforcement boost signal, 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 an optimal air-fuel ratio not only in the steady state of the engine but also in the transient state, thereby obtaining the optimal operation of the engine (see, for example, Japanese Patent Laid-Open No. 56-6034).

In the above-mentioned type of device, changes in the engine over time, such as changes in characteristics due to deposits on the injector nozzle in pulp clearance and EFI, deposits on the back of the cylinder intake valve, etc. The aging of these engines takes into account changes in properties caused by viscous substances such as carbon particles derived from i oil components and combustion products, and changes in properties caused by changes in volatility due to variations in gasoline properties. Since there is no means to detect changes in the air-fuel ratio from the optimum 1ii during acceleration due to changes in the properties of gasoline, gasoline with poor volatility may be used, or the mixture during acceleration may change due to changes in the engine over time. Drivability deteriorates due to dilution of the gas, such as sluggishness during acceleration, and conversely, when gasoline with good volatility is used, the mixed gas becomes richer during acceleration, resulting in poor fuel efficiency and poor emissions. The problem was that it was possible.

FIG. 1 illustrates the fluctuations in the air-fuel ratio in this case, and the fluctuations in the case where a deposit is attached to one side of the intake valve. In Figure 1, A/F (0) is De, J?
The changes in the air-fuel ratio after the deposit is applied to the A/F (DEP) before the deposit is deposited are shown as 1° ACC.
is the acceleration point, A/F (OPT) is the optimum fuel ratio, and A
/F (LN) is the lean side, A/F CRC
Ii) is the rich side, respectively.

In addition, injector blindness can be corrected by feedback from the air-fuel ratio sensor in steady state, but in acceleration mode, the same problem occurs because there is no correction means. Also, the engine.

Similar problems have arisen due to variations in the manufacturing process of air flow meters and changes over time.

Figure 2 illustrates the fluctuations of summer gasoline G (S) and winter gasoline G (W) when the gasoline properties are changed. The same problem arises as in the case of profiteering.

Gasoline is generally marketed with different characteristics, such as for summer and winter use, with the same gasoline throughout the four seasons. Reed vapor pressure and distillation properties are well known as the value that indicates the volatility of gasoline, but when we looked at gasoline manufactured by a certain manufacturer, we found that the Reed vapor pressure was ”, 0.5 U/cgfim2~0.86/r
, Shika 12, and the temperature at the time of 10-chi distillation also vary from 40 to 58 °C, and changes in volatility due to similar gasoline properties cause wall fuel ratio λ fluctuations such as No. 21g + ◇ No. 2
The figure shows an example of a change to the lean side, but it can also change to the rich side.

The main purpose of the invention is to compensate for the air-fuel ratio deviation from the optimum air-fuel ratio determined by detecting the total fuel ratio deviation, using fuel stone increase compensation during acceleration, in view of the problems with the conventional type described above. Increase fuel during acceleration 1. Based on the first to Y ideas of adjusting If the engine or intake air t1. “From the optimum air-fuel ratio of the mixed gas during acceleration due to changes in the detection device over time”
The object of the present invention is to improve drivability while completely preventing engine slippage and reducing the ratio of emissions and fuel consumption.

The present invention is designed to reduce not only changes over time, but also differences in gasoline properties, shortcuts during engine manufacturing, Q's during manufacturing of air meters, and acceleration due to fluctuations in 114-a gas mixtures.
lj-The optional purpose is to prevent air-fuel ratio deviation from the optimum air-fuel ratio.

The invention (1.I kite charcoal 3 light and stone) also detects the acceleration of the chest and increases the 1st gear 11 mo Hongmian fuel h4, so the internal combustion 42 chopper An internal combustion engine that detects a deviation of the air-fuel ratio from a set air-fuel ratio during acceleration, and extracts pressure from the fuel expansion section during acceleration in accordance with the detected ratio deviation. A fuel ratio control method is provided.

The present invention, Q, is based on the conduct of the original Akiyoshi. Figures 3 (A), (B) and 4
The figure shows the air-fuel ratio behavior during acceleration, that is, the maximum deviation value D (A/F (RCH)) of the optimal air-fuel ratio A/F (OPT) d to the air-fuel ratio rich side or the air-fuel ratio lean 111j during acceleration. Maximum deviation value D (A/F (LN) J
and the behavior of the air-fuel ratio sensor during acceleration, that is, the time during which the air-fuel ratio sensor 6 detects the rich state of the mixed gas,
In other words, they are a waveform diagram and a characteristic diagram showing the relationship between the rich continuation time T (RCH) during acceleration or the time T (LN) during which the lean state of the mixed gas is detected. Figure 3 (A)
, (B) and η) In Figure 4, ACC represents acceleration,
5 (6) detects the air-fuel ratio sensor signal.

As shown in FIGS. 3(A), (B) and 4, even if the mixed gas changes from the optimum air-fuel ratio A/F (OPT) to the rich side or lean side during acceleration, the signal from the air-fuel ratio sensor, T (LN) or T (RCH), its variation it
11 can be detected accurately. That is, it is possible to accurately detect the air-fuel ratio of the mixed gas during acceleration from the air-fuel ratio sensor signals T(RCH) and T(LN) during acceleration.

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 1 in the device shown in FIG. 5 is shown in FIG.

In the device shown in FIG. 5, reference numeral 1 indicates a known electronically controlled fuel injection six-cylinder spark ignition engine which is a power source for automatic operation, and reference numeral 2 indicates a known intake air amount detection device for detecting air intake into the engine 1. 0.3 is a known rotation speed sensor that detects the engine 10 rotation speed, 4 is a known water temperature sensor that measures the cooling water temperature of the engine 1, 5 is the exhaust passage of the engine 1, and 6 is installed in the exhaust passage 5. A known air-fuel ratio sensor J7 is an intake pipe of the engine I, 8 is a known electromagnetic fuel injection valve provided in the intake pipe 7, 9Q is a throttle valve that controls the amount of air taken into the engine 1, 91 is a known throttle sensor C that detects the movement of throttle valve 9.
0NT is a control circuit that operates the fuel injection valve 8 using a fuel needle that supplies the engine 1.

The amount of fuel supplied to the engine 1 is controlled by the control circuit C0NT when the engine is in a steady state.
The basic fuel amount is determined from the detection signals of the rotation angle sensor 3 and the water temperature sensor 4, and the feedback correction amount determined from the signal of the air-fuel ratio sensor 6 is further corrected to determine the opening time of the fuel injection valve 8.

Further, the control circuit C0NT is configured to increase the amount of fuel during acceleration beyond the amount of fuel set during steady state when the acceleration state of the engine 1 is detected by the throttle sensor 91 or the intake air detection device 2. .

As shown in FIG. 6, the control circuit C0NT has the intake air amount sensor 2 and water? 1□, V sensor 4
A multiplexer 101 that receives signals from the AD converter 102, a shaping circuit 103 that receives the 4E of the air-fuel ratio sensor 6, a human power driver that receives signals from the shaping circuit and the throttle sensor 91, and a signal from the rotation sensor 3. It has an input counter 105 that receives input. Control LIJ
l path also includes path 106, ROM 1.07, CPU
108, RAM 109, output counter 110, and i
The 9-power drive unit 111 is equalized. The output of the power drive section 111 is supplied to the fuel injection valve 8.

As the control circuit C0NT, a microcomputer type circuit can be used, for example, a Toyota TCC8 type circuit can be used. Split part 1 circuit CON'l'
K is for festival! ) Ratio deviation detection capacity and acceleration fuel increase? t
If regular function has been added.

A schematic flowchart of the control program of the control circuit C0NT is shown in FIG. This program is an electronic FII
This is for performing J Gomenehiro injection, and step 5100-
Consists of 8108.

Starting at S 100, at 5IOI,
Memory, input/output cuff I? Convert l to J for the first time. 510
In step 2, the basic fuel injection interval is calculated based on the intake air amount data Q, the engine rotation speed data N, and the water temperature sensor data θ and V. At 8103, the basic fuel injection ratio is corrected by performing feedback control using the signal from the air-fuel ratio sensor 6 so that the air-fuel ratio remains constant.

In step 8104, the initial acceleration fuel is added and the air-fuel ratio deviation is detected, and in step 5105, the air-fuel ratio deviation is corrected to the initial acceleration fuel Rjt/max. 5I06 determines one revolution of the engine, and one rotation of the engine 4U, S107, one time try injection of the leakage charge - Jr'8, 17tj valve + rg, 7
(1' Calculated from the basic fuel u and the fuel increase during acceleration, corrected by hack flj II, '8108
A detailed flowchart of the air-fuel ratio deviation detection process in the flowchart of FIG. 7 is shown in FIG. A flowchart is shown in FIG.

Acceleration 10; 1 positive t, S'201 not shown in Figures 8 and 9
As shown in , for a certain period of time (e.g. 32.7 ms) 1
Process g. Air-fuel ratio deviation f: As a method of nuclear detection,
The output 4Fi of the air-fuel ratio sensor 6 is compared with a constant voltage level to detect the two values of the lean state and rich state of the mixed gas, and calculate the acceleration 1 + y Nori 1 continuation time T (LN ) and the rich duration T (using the method of measuring RC palanquin).

In order to facilitate the detection of air-fuel ratio deviation during transient periods, 820
3, 8204, within 5 seconds after acceleration, engine speed 9
Lean duration T (LN), rich duration T (IζC1()
Measure and do. In addition, 5205 provides a feedback system (one time during i111) so that rich and lean appear alternately.

At 8206, rich and lean are determined. For Lean 5
At 207, the lean compensation counter is decremented by -1-1, and T
(LN) in 32.7 ms units.
Ru. Next, at 8208, the value of the rich time counter is 12.
It is determined whether the eclipse (rich time limit) has been exceeded, and if so, the rich correction counter is incremented by 1 in step 5209. Next, in step 5z10, the rich time counter is set to 0.

If 8206 is determined to be rich, 8211 to 5
At step 214, the rich time counter is increased by 1 and lean time is determined. The degree of air-fuel ratio deviation during acceleration can be determined from the values of the lean correction counter and rich correction counter set in 5206 to 5214 described above.

If the rich time limit in 5208 is set too high, the rich time counter's f direct T(RcI()
can be set to any value. In the d55 illustration, the air-fuel ratio during acceleration is f! l! In order to set the rich time limit value to a value slightly on the side of the stoichiometric air-fuel ratio, or by increasing the rich time limit value, the air-fuel ratio during acceleration can be made richer. Control improves drivability.゛Here, T (RCH) and D (A/F (RCH)) are shown in Figure 3 (Al, (
B), as shown in Figure 4, is determined intentionally, so this result D (
Since the A/F (RCH) can be controlled to a high time limit, that is, a constant rich A/F value with high precision, emissions do not deteriorate and furthermore, good drivability is maintained. The air-fuel ratio A/F during acceleration can further be varied by changing the value of the rich time limit depending on the cooling water temperature to make the air-fuel ratio A/F controlled rich on the low temperature side variable.

In FIG. 9, at 5301, the rate of change Δ of the intake air amount VN per one rotation of the engine reflex is calculated by combining the intake air amount signal Q from the intake air wind detection device 2 and the rotation speed signal N from the rotation speed detection device 3. (Q/N).

If Δ(Q/N) is positive, the engine is accelerating. Therefore, in 8302, if Δ(Q/N) is positive and equal to or greater than a certain value, it is regarded as acceleration, and the process proceeds to 8303.

8303, the fuel increase value during acceleration is determined by cooling water temperature, Δ(Q/
N), it is determined that the lean correction counter and rich correction counter are broken. Basically, the unit Δ(Q
/N) Store the current increase t1 and ratio in a map in advance, take out the increase nt ratio for the water temperature, multiply it by Δ(Q/N), and calculate the lean correction counter. A correction is made based on the value of the counter, and the fuel increase during acceleration 1 value is calculated. This increase value is an initial value at the time of acceleration detection. 5304,
At 5305, the fuel power increase f1 during acceleration is performed every one rotation of the engine.
By subtracting a certain amount of candy from 0, it decays to 0.

Therefore, as shown in Figure 10, (1) When the throttle is opened and accelerated @,
, (2) the Q/N value also increases, (3) the fuel increase ratio R during acceleration increases with a waveform as shown in the diagram, and (4)
) The fuel injection valve opening time U is determined and fuel is supplied.

In carrying out the present invention, various modifications may be made to the embodiments described above. For example, in the above-mentioned embodiment, when the deposit is attached, the fuel increase during acceleration is 1.
The initial value of the value was changed depending on the value of the lean correction counter and the switch correction counter.
As shown in the flowchart for 111g+, when accelerating 1
is determined using only the water temperature θ7 and Δ(Q/N), regardless of the air-fuel ratio deviation, and in addition, it is also possible to perform a correction acceleration increase when an air-fuel ratio deviation or the like occurs.

In FIG. 11, when acceleration is detected in 5402, the increase value during acceleration is determined in 8403 by combining the cooling water temperature and Δ(Q/N).
To confuse. Next, in step 5404, a corrected acceleration fuel increase value when an air-fuel ratio deviation occurs is calculated.

In this calculation, the acceleration fuel increase correction value is calculated according to the air-fuel ratio deviation correspondence A1η as a function of four variables: cooling water temperature, lean correction counter value, S, H correction counter value, and Δ(Q/N). .

Each rotation of the engine, a constant value Cyx is determined from the increase value during acceleration and the acceleration increase correction value when air/fuel ratio deviation occurs.
arp) and decays to O. This acceleration increase ratio and the normal acceleration increase ratio when an air-fuel ratio deviation occurs are applied to the basic injection fuel to increase the amount of fuel.

Effects of the Invention According to the present invention, deviations from the optimum air-fuel ratio of the mixed gas during acceleration due to changes in the engine and intake air amount detection device over time (such as deposits on the back of the intake valve and clogging of the injector), This makes it possible to improve drivability while preventing deterioration in emissions and fuel efficiency.

[Brief explanation of drawings]

Figure 1 shows how the air-fuel ratio fluctuates when deposits form on the back of the intake valve, Figure 2 shows how the degraded fuel ratio fluctuates when the gasoline properties are changed, and Figure 3 (A ), (Figure 4 is a waveform diagram and characteristic +g+ showing the relationship between air-fuel ratio behavior during acceleration and air-fuel ratio sensor 4 movement during acceleration, and Figure 5 shows an air-fuel ratio control method for an internal combustion engine as an embodiment of the present invention. Fig. 6 shows the 4'ljt configuration of the f1714 (i11 circuit in the Fig. 5 device), Fig. 7 shows the flow of the Flow lyl, Figure 8 shows the ratio/deviation detection process to nitrogen lamp tii”++411
Figure 819 shows the initial acceleration fuel 8Jlj L and J' of ξ.
Fuel during acceleration for ajii'erIJ:'I supplementary;
1P7411 IM >'4 flowchart, Figure 10 is a waveform diagram showing the operation of the device in Figure 5, Figure 11 is the performance of Figure 9 >1-
FIG. 6 is an operation diagram showing another example of the flow. (Explanation of No. 9) l...Engine, 2...Cane person air amount detection device fll:
j, 3...Rotation speed sensor, 4...Water temperature sensor!
5...Kankitsu 1'! Lj' %6...Air-fuel ratio sensor, 7...Intake '1-1.8...Fuel valve, 9...
Throttle valve, 9]...Throttle valve, C0N
T... control side 1 time IllLt0 Figure 1 Figure 2 111 Figure 3 (A) (B) Figure 10 T)-1 - 11111 Mall 1st page continuation 0 shots Name: Kunihiko Sato 190 Toyota Motor Corporation Toyotacho Toyotacho 1

Claims (1)

[Claims] 1. In order to detect acceleration of the internal combustion engine and increase the amount of fuel supplied during acceleration, detect individual differences in air-fuel ratio from a set air-fuel ratio during acceleration of the internal combustion engine, 1. A method for controlling an air-fuel ratio of an internal combustion engine, comprising correcting the acceleration fuel welfare value in accordance with an air-fuel ratio deviation. 2. The method according to claim 1, wherein the air-fuel ratio deviation detection is performed using an air-fuel ratio sensor. 3. The method according to claim 1, wherein the set air-fuel ratio is a richer air-fuel ratio than the stoichiometric air-fuel ratio of the internal combustion engine. 4. The set air-fuel ratio is an air-fuel ratio that is faster than the stoichiometric air-fuel ratio of the internal combustion engine, and is set so that the fuel ratio becomes richer when the internal combustion engine temperature is low. , the method according to claim 1.