JPS58150057A - Study control method of air-fuel ratio in internal-combustion engine - Google Patents

Abstract

PURPOSE:To always perform a correct study in the method of correctively studying a correction coefficient of air-fuel ratio when the air fuel ratio is set in acccordance with a deviation between the detected air-fuel ratio and the target air fuel ratio, by performing the study in every prescribed region within a study range of intake pipe pressure or intake air quantity. CONSTITUTION:The basic injection timing calculated from an intake pipe pressure sensor 23 and crank angle sensor 44 is corrected in accordance with a deviation between the air-fuel ratio by an O2 sensor 34 and the target air-fuel ratio in a digital control circuit 54. While an air-fuel ratio correction coefficient, used when air-fuel ratio is set in accordance with said deviation, is correctively studied. Here said correction coefficient is studied in every prescribed region within a study range of intake pipe pressure or intake air quantity. Then at air- fuel ratio control, an air-fuel ratio correction coefficient in the upper limit region within the study range is used for a region exceeding the upper limit of said study range and/or an air-fuel ratio correction coefficient in the lower limit region within the study range is used for a region below the lower limit of the study range.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio control method for an internal combustion engine.
WIK is suitable for use in automobiles equipped with an intake pipe pressure type electronically controlled fuel injection system.

When the air-fuel mixture at the set air-fuel ratio is combusted, the air-fuel ratio of the air-fuel mixture is feedback-controlled according to the deviation between the air-fuel ratio of -gas and the target air-fuel ratio, and the air-fuel ratio of the air-fuel mixture is controlled according to the correction described above. This invention relates to an improvement in an air-fuel ratio learning control method for an internal combustion engine by learning and correcting an air-fuel ratio correction coefficient used when setting an air-fuel ratio.

In internal combustion engines, especially in automobiles where exhaust gas purification measures are taken using a three-way catalyst, the air-fuel ratio of the gas must be kept strictly close to the stoichiometric air-fuel ratio.
Therefore, for example, when using an air-fuel ratio sensor such as an oxygen concentration sensor that detects the air-fuel ratio from the residual oxygen concentration in the gas,
Air-fuel ratio control means consisting of an electronically controlled fuel injection device that controls the air-fuel ratio of the air-fuel mixture by controlling the amount of fuel injection is used to control the air-fuel ratio of air-fuel mixture! The pressure difference is the amount of intake air and 1
727 In addition to the basic injection amount determined according to the rotation speed, engineering/engineering/engineering/cooling water temperature, throttle valve opening, deviation between the exhaust gas air-fuel ratio of the air-fuel ratio output and the target air-fuel ratio, etc. /By injecting fuel with feedforward and feedback increase/decrease correction according to the operating condition, the air-fuel ratio of the air-fuel mixture is feedforward and feedback controlled, and the basic injection amount is feedforward according to the deviation. An air-fuel ratio learning control method for an internal combustion engine has been proposed in which an air-fuel ratio correction coefficient used when making an increase/decrease correction is learned and corrected.

According to such an air-fuel ratio learning control method, it is possible to detect individual differences and changes over time in various stages in order to detect engine/engine/driving collisions.
Alternatively, since the air-fuel ratio correction coefficient is learned and corrected according to weather conditions, the fuel injection amount is always feedforward controlled at an air-fuel ratio close to the target air-fuel ratio, resulting in a good control with less delay due to feedback control. It has the feature of being able to perform air-fuel ratio control.

Oka, as a method of learning the air-fuel ratio correction coefficient,
Since there is an appropriate air-fuel ratio correction coefficient for each operating state, it is conceivable to learn the air-fuel ratio correction coefficient t1 for each predetermined region of intake pipe pressure or intake air amount, for example. However, if you study and practice the air-fuel ratio correction coefficient over the entire range of intake pipe pressure or intake air amount,
? In addition, in the high load range where the intake pipe pressure or intake air amount is above a predetermined value, or in the low load range where it is below a predetermined value, there are many transient periods, which not only disrupt the air-fuel ratio but also provide learning opportunities. Since there are only a few, learning in such areas may actually have the opposite effect. In order to prevent such drawbacks, it may be possible to limit the learning range of the air-fuel ratio correction coefficient, but in this case, the Fi and school capital results are only applied to air-fuel ratio control in the area within the school capital range, and the learning control b.
It had some problems.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional technology, and it is possible to learn a highly accurate air-fuel ratio correction coefficient that is not affected by transient conditions. and a wide range including low load range I! It is an object of the present invention to provide an air-fuel ratio learning control method for an internal combustion engine that can be applied to perform air-fuel ratio control in a favorable manner.

The present invention performs feedback control of the air-fuel ratio of the air-fuel mixture according to the deviation between the air-fuel ratio of exhaust gas and the target air-fuel ratio when the air-fuel mixture of the set air-fuel ratio is combusted, and also controls the air-fuel ratio of the air-fuel mixture according to the deviation. In an air-fuel ratio learning control method for an internal combustion engine, the air-fuel ratio correction coefficient is adjusted by adjusting the intake pipe pressure or the intake air amount. In addition to learning for each predetermined area within the learning range, when controlling the air-fuel ratio in an area exceeding the upper limit of the learning range, use the air-fuel ratio correction coefficient in the upper limit area within the learning range, or/and using the air-fuel ratio correction coefficient in the upper limit area of the learning range. When controlling the air-fuel ratio in the region below , the above objective is achieved by using the air-fuel ratio correction coefficient in the lower limit region within the learning range.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An actual 1/IA example of the present invention will be described in detail below with reference to the drawings.

An embodiment of an intake pipe pressure type electronically controlled fuel injection device in which the air-fuel ratio learning control method for an internal combustion engine according to the present invention is adopted is as shown in Figures 1 and 2 of Tsuru, an air cleaner 12 for taking in outside air. and an intake temperature set 14 and % for detecting the temperature of the intake air taken in from the air cleaner 12.
A valve 1B is disposed in the intake passage 16 and can be opened and closed in conjunction with an accelerator pedal (not shown) disposed on the driver's seat, for controlling the flow rate of intake air.

A throttle controller 20 including an idle contact for detecting whether or not the throttle valve 18 is at the idle opening and a voltage output proportional to the opening of the throttle valve 9 1BC1, and a surgitator. 22 and cough-jita/ri22
an intake pipe pressure gauge/su 23 for detecting the intake pipe pressure from the pressure within the intake pipe, and a bypass passage 24 that bypasses the throttle valve 1s.

A round idle rotation control valve 26 is disposed in the middle of the bypass passage 24 and controls the idle rotation speed by controlling the opening area of the bypass passage 24; an injector 30 for injecting fuel toward the intake port of the exhaust gas; and an oxygen concentration upper/suction 34 disposed in the exhaust manifold 32 for detecting the air-fuel ratio from the residual oxygen concentration in the exhaust gas. , a 93-way catalyst converter 38 disposed midway in the exhaust pipe 36 on the downstream side of the exhaust pipe 32, and a distributor shaft that rotates in conjunction with the rotation of the engine/engine/10 crankshaft. a top dead center center 42 and a top dead center center 44 which are built into the distributor 40 and output a top dead center signal and a cradle/turn angle signal in accordance with the rotation of the distributor shaft; and engineering/
A round cooling water temperature sensor 46 that detects the cooling water temperature and a ninth vehicle speed sensor that detects the running speed of the vehicle from the rotation speed of the output shaft of the transmission 48 are arranged in the engine block. The valve opening of the engine 9 and the cooling water temperature control are determined based on the intake pipe pressure of the intake pipe pressure cassette 23 and the output of the crank angle sensor 44. /S46 output power/cooling water temperature, oxygen concentration set/S34
By adding feedforward and feedback increase/decrease corrections according to the operating conditions such as the deviation between the exhaust gas air-fuel ratio detected from the output and the target air-fuel ratio,
Determine the fuel injection amount and output a valve opening time signal to the injector 30, and further correct the air-fuel ratio correction coefficient used when correcting the basic injection amount t-feedforward increase/decrease according to the deviation. Further, a digital control circuit 54 is provided which determines the ignition timing according to the work/engine/driving conditions and outputs an ignition signal to the igniter-equipped coil 52, and further controls the idle rotation control valve 26 during idle. In the intake pipe pressure type electronically controlled fuel injection device of Automotive Engineer/J/10, the air-fuel ratio correction coefficient is learned for each predetermined region within the range of intake pipe pressure in the digital control circuit 54, and When controlling the air-fuel ratio in an area exceeding the upper limit of the learning range, use the air-fuel ratio correction coefficient in the upper limit area within the learning range, and when controlling the air-fuel ratio in an area below the lower limit of the learning range, use the air-fuel ratio correction coefficient in the upper limit area within the learning range. The air-fuel ratio correction coefficient in the lower limit range is used, and 9 is also 0.

As shown in detail in FIG. 2, the digital control circuit 54 includes a central processing unit (hereinafter referred to as CPU) 60 consisting of a microprocessor that performs various arithmetic operations, the intake temperature control unit 14, and the throttle control unit 20. Bote/Shometa,
An analog input port 2 with a multiplexer for converting analog signals input from the intake pipe pressure upper/[3% oxygen concentration center 34, cooling water temperature center 46, etc.] into digital signals and sequentially inputting them into the CPU 60. , said throttle control/
A digital input port controller is provided for inputting digital signals input from the idle contact of the 20, the top dead center center 42, the crank angle 44, and the vehicle speed 50 to the CPU 6G at a predetermined timing. 4, read-only memory (hereinafter referred to as ROM) for storing programs or various constants, etc.
) 66, a storage/dam access memory (hereinafter referred to as RAM) 68 for temporarily storing calculation data etc. in the CPU 60, and a backup memory that can be supplied with power from an auxiliary power source and retain memory even when the engine is stopped. / Dumb access memory (hereinafter referred to as backup RAM) 70
, a digital output door for outputting the calculation results in the CPU 60 to the idle rotation control valve 26, the engine ignitor 30, the igniter-equipped coil 52, etc. at a predetermined timing, and a communication path connecting the above-mentioned components. 7
It is composed of 4.

The action will be explained below.

First, the digital control circuit 54 stores in advance in the ROM 66 the intake pipe pressure PM output from the intake pipe pressure cassette 23 and the engine speed NE calculated from the output of the crack angle cassette 44. From the map, basic injection time TP (
RM, NE).

Furthermore, the fuel injection time TAU calculation ratio is calculated by correcting the basic injection time TP (PM, NE)l using the following formula according to the signals from each cell.

TAU=to*TP(PM,NB)*(1+F)・
... (1) Here, K is an air-fuel ratio correction coefficient (initial value = 1) that is corrected by 1, and F is corrected according to engineering/engine/operating conditions 111. This is a correction coefficient including an air-fuel ratio feedback correction coefficient, and when F is positive, it represents an increase correction, and when F is negative, it represents a reduction correction.

A fuel injection signal corresponding to the nine fuel injection times TAU determined in this way is output to the injector 30 and
The injector 30 injects fuel for a fuel injection time T in synchronization with the engine/rotation.
Only AU is opened, intake manifold 28 of Ensif 10
Fuel is injected inside.

Specifically, learning of the air-fuel ratio correction coefficient is performed according to a program as shown in FIG.

That is, first in step 101, the intake pipe pressure PM at that time is
If the 0 judgment result for determining whether or not exceeds the upper limit P4 of the learning range of intake pipe pressure is positive, that is, if the intake pipe pressure PM exceeds the upper II value P4 of the learning range. is often in a transient operating state, and the air-fuel ratio is also disturbed, so this program is terminated without learning the air-fuel ratio correction coefficient. On the other hand, if the determination result in step 101 is negative, the process proceeds to step 102, where it is similarly determined whether the intake pipe pressure PM is equal to or higher than a predetermined value Pa (<P4). If the determination result is positive, the process proceeds to step 103, where the air-fuel ratio correction coefficient corresponding to the upper limit region within the 1 range is learned.

In step 104, the information is stored in the register Ka, and this program ends. On the other hand, if the determination result in step 102 is negative, proceed to step 105,
Intake pipe pressure PM is a predetermined value P.

(<Ps) or more, it is determined whether or not. If the determination result is positive, proceed to step 10g.

Air-fuel ratio correction coefficient Kit corresponding to the intermediate region within the learning range
learned and stored in register Kg in step 107,
Exit this program. On the other hand, step 105 mentioned above
If the determination result in is negative, the intake pipe pressure PM
is the lower limit value P of the learning range.

(<P嘗) If the 0 determination result is positive, the process proceeds to step 109.

Air-fuel ratio correction coefficient K corresponding to the lower limit region of the school funds range.

is learned and stored in register KIK in step 110, and this program is terminated. On the other hand, if the determination result in step 108 is negative, if the intake pipe pressure PM is less than the lower limit value 21 of the learning range, it is likely that the engine is in a transient operating state.

Since the air-fuel ratio is also disturbed, this program ends without learning the air-fuel ratio correction coefficient.

The air-fuel ratio correction coefficient learned as described above is set to 1 to 1.
Calculation of the fuel injection time TAU using is performed as shown in FIG.

That is, first, in step 201, the intake pipe pressure P at that time is
The basic injection time TPt is determined from a map stored in the ROM 66 in advance according to M and the engine/engine/rotational speed Ng.

Next, the process proceeds to step 202, where the intake pipe pressure P at that time is
It is determined whether M is greater than or equal to the lower limit value 23 of the upper limit area within the learning range.

If the determination result is positive, proceed to step 203;
As shown in the following equation, the fuel injection time TAU is calculated using the air-fuel ratio correction coefficient of the upper limit range within the academic range stored in the register 3.

TAU, 3*TP*(1+F)...
(2) On the other hand, if the determination result in step 2020 is negative, the process proceeds to step 204, where the intake pipe pressure PM at that time
It is determined whether or not is less than or equal to the lower limit P of the intermediate region within the learning range. If the determination result is positive, the process proceeds to step 205, where the value is stored in the register 2 as shown in the following equation. For the air-fuel ratio correction coefficient in the middle range within the learning range!
The fuel injection time TAU is calculated using

TAU=2*TP*(1+F)...(3
) If the determination result in step 204 is negative, the process proceeds to step 208, where VC is stored at 1 in the register as shown by the linear equation. The fuel injection time TAUt is calculated using 1t as the air-fuel ratio correction coefficient in the lower limit region within the learning range.

1*TP*(1+F)...(3
) As is clear from the diagram 0 shown in FIG. 5, which shows the relationship between the range of intake pipe pressure PM and the scope of application of the results of study 1 in this example, in this example, the learning of the air-fuel ratio correction coefficient is This is performed for each predetermined region within the learning range where the pressure is within the range of P1 to P4, and when controlling the air-fuel ratio in the region exceeding the upper limit of the educational range, the air-fuel ratio correction coefficient of the upper limit region within the educational range is used.

Furthermore, when controlling the air-fuel ratio in a region below the lower limit of the learning range, the air-fuel ratio correction coefficient in the lower limit region within the learning range is used, so that accurate learning of the air-fuel ratio correction coefficient is possible. Moreover, the scope of application of the learning results is also very wide, and the control accuracy of the air-fuel ratio can be improved.

In this embodiment, the air-fuel ratio correction coefficient in the upper limit region within the learning range is not only expanded and applied to the air-fuel ratio control in the region exceeding the upper limit of the learning range, but also learns the air-fuel ratio correction coefficient in the lower limit region within the learning range. Since the air-fuel ratio control is expanded and applied to the air-fuel ratio control in the region below the lower limit of the range, particularly highly accurate air-fuel ratio control can be performed. Note that it is of course possible to omit either one of them.

Further, in the embodiment described above, the learning range of the air-fuel ratio correction coefficient is divided into three regions, but the number of divisions within the learning range of the air-fuel ratio correction coefficient is not limited to this.

In the above-mentioned Example Fi, the present invention is applied to a nine-vehicle vehicle equipped with an intake pipe pressure type electronically controlled fuel injection device; however, the scope of application of the present invention is not limited thereto, and an internal combustion engine equipped with an electronically controlled fuel injection device, or
It is clear that the invention can be similarly applied to internal combustion engines equipped with general electronically controlled fuel injection devices.

As explained above, and according to the present invention, the air-fuel ratio correction coefficient can be accurately learned by trap learning without being affected by transient conditions, etc. It has excellent effects that can be applied to a wide range of areas, including good air-fuel ratio control.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of an intake pipe pressure type electronically controlled fuel injection equipment for automobiles in which the air-fuel ratio learning control method for an internal combustion engine according to the present invention is adopted. FIG. 2 is a block diagram showing the configuration of the digital control circuit used in the above embodiment, and FIG. 3 is a flowchart showing a rounding program for learning the air-fuel ratio correction coefficient. , a flowchart showing a program for calculating the fuel injection time based on the learning results, and FIG. 5 is a diagram showing the relationship between the learning area of the intake pipe pressure and the application range of the learning results in the same embodiment. 10...work/di/% 14...intake temperature set/su, 1
8... Throttle valve, 20... Throttle control/su, 23... Intake pipe pressure control/su, 30... I/director, 34... Oxygen concentration control/su. 40...Distributor. 42...Top dead center/su, 44...C/R corner/su, 46...Cooling water temperature/su, 54...Digital control circuit. =41

Claims (1)

[Claims] (1) When the air-fuel mixture with the set air-fuel ratio is combusted, the air-fuel ratio of the air-fuel mixture is feedback-controlled according to the deviation between the air-fuel ratio of exhaust gas and the target air-fuel ratio, and the air-fuel ratio of the air-fuel mixture is controlled according to the deviation. In an air-fuel ratio learning control method for an internal combustion engine that learns and corrects an air-fuel ratio correction coefficient used when setting an air-fuel ratio of air, the air-fuel ratio correction coefficient is set within a learning range of intake pipe pressure or intake air amount. In addition, when controlling the air-fuel ratio in a region exceeding the upper limit of the learning range, use the air-fuel ratio correction coefficient in the upper limit region within the learning range, or adjust the lower limit of the learning range to A method for learning and controlling an air-fuel ratio of an internal combustion engine, characterized in that an air-fuel ratio correction coefficient in a lower limit region within a learning range is used when controlling the air-fuel ratio in a lower region.