JPS6017240A - Study control method of air-fuel ratio in electronically controlled engine - Google Patents

Abstract

PURPOSE:To improve the controllability of air-fuel ratio, by providing a procedure to decide the change of amount in intake pipe pressure or intake air, procedure to decide continuation of feedback control and a procedure to inhibit study control. CONSTITUTION:An electronic control unit (ECU) 40 performs both feedback control of air-fuel ratio in accordance with a deviation of actual air-fuel ratio from the preset air-fuel ratio and study control by studying the deviation when the feedback control is executed. A procedure to decide whether or not the change of amount per unit time in intake pipe pressure or intake air per one revolution of an engine exceeds the preset value, a procedure to decide whether or not the feedback control is continued for over a preset time after said change of amount exceeds the preset value to again decrease below the preset value and a procedure to inhibit the study control when the feedback control is not continued for over the preset time are provided. In such way, the study control in high reliability can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio learning control method for an electronically controlled engine, and particularly relates to an air-fuel ratio learning control method for an electronically controlled engine. Suitable for use in an automobile engine equipped with a squirt device, the air-fuel ratio feedback control is performed according to the deviation between the set air-fuel ratio and the actual air-fuel ratio, and the learning control is performed by learning the deviation during feedback control execution. This invention relates to an improvement in an air-fuel ratio learning control method for an electronically controlled engine.

In internal combustion engines, especially automobile engines that use three-way catalysts to purify exhaust gas, it is necessary to maintain the air-fuel ratio of the exhaust gas strictly close to the stoichiometric air-fuel ratio. Using an oxygen 11 degree sensor that detects the fuel ratio and an air-fuel ratio control means that controls the air-fuel ratio of the air-fuel mixture, air-fuel ratio feedback control is performed according to the deviation between the set air-fuel ratio and the actual air-fuel ratio, and feedback control is also performed. An air-fuel ratio learning control method has been proposed in which learning control is performed by learning the deviation during execution.

According to such an air-fuel ratio learning control method, the air-fuel ratio is academically corrected in accordance with individual differences and aging of various sensors for detecting environmental conditions or engine operating conditions.
It has the feature of being able to perform good air-fuel ratio control.

However, in the past, when the intake pipe pressure suddenly changed, the air-fuel ratio temporarily went out of order due to the influence of changes in the amount of evaporation of the fuel layered in the intake pipe, and the air-fuel ratio feedback control was disrupted, causing the control value to change when the engine Even when the correct characteristics of the air-fuel ratio are not shown, the learning control is executed based on the feedback control value to correct and calculate the learned δ value, so the learned value becomes an incorrect value and the air-fuel ratio This has the problem that learning control may not be performed.

The present invention has been made in order to solve the above-mentioned conventional problems, and it is possible to appropriately calculate the deviation between the set air-fuel ratio and the actual air-fuel ratio, and therefore, it is possible to perform highly reliable learning control. The purpose of this paper is to provide an air-fuel ratio learning control method for electronically controlled engines.

The present invention provides air-fuel ratio learning control for an electronically controlled engine that performs air-fuel ratio feedback control according to a deviation between a set air-fuel ratio and an actual air-fuel ratio, and also performs learning control by learning the deviation of the feedback control execution verse. In the method, the first
As shown in the figure, there is a procedure for determining whether the amount of change per unit time in intake pipe pressure or intake air amount per engine revolution exceeds the set value, and After the amount of change exceeds the set value, or when the feedback control becomes below the set value again, the procedure is to determine whether or not the feedback control (1) continues for the set time or not. The above purpose has been achieved by including a procedure for prohibiting study and study when the above is not continued.

In the present invention, it is determined whether the amount of change per unit time in the intake pipe pressure or the amount of intake air per engine revolution exceeds a set value, and when the amount of change exceeds the set value, or After the amount of change exceeds the set value and becomes below the set value again after IC, learning control is prohibited if feedback control has not continued for more than the set time, so the set air-fuel ratio and actual air Deviations in fuel ratio can be learned appropriately, and learning control with high reliability can therefore be performed.

Hereinafter, with reference to the drawings, an embodiment of an automobile engine equipped with an intake pipe pressure sensing type electronically controlled fuel injection device 9A, in which the air-fuel ratio learning control method for an electronically controlled engine according to the present invention is adopted, will be explained in detail with reference to the drawings. do.

In this embodiment, as shown in FIG. 2, an intake air temperature sensor 12 for detecting the temperature of intake air taken in from the outside and a throttle body 14 are installed. A throttle valve 16 for controlling the flow rate of intake air, which is opened and closed in conjunction with an accelerator pedal (not shown) disposed in the driver's seat, and a throttle valve 16 that controls the opening degree of the throttle valve 16. A throttle sensor 18 for detection, a surge tank 20 for preventing intake interference, and an intake pipe pressure sensor 2 for detecting the pressure of intake air in the surge tank 2o.
2, 1c disposed in the intake manifold 24, and engine 1
Pressurized fuel is intermittently injected towards the intake boat of each cylinder of ゜! )! An injector 26 for IJ, a spark plug 28 for igniting the air-fuel mixture introduced into the engine combustion chamber 10A, and an exhaust manifold 3o for detecting the rich-lean state of the exhaust air-fuel ratio. An oxygen concentration sensor (hereinafter referred to as 02 sensor) 31, a catalytic converter 32 filled with, for example, a three-way catalyst and arranged downstream of the O2 sensor 31, and high pressure generated by an ignition coil 33. a distributor 34 having a distributor shaft 34A that rotates in conjunction with the rotation of the crankshaft of the engine 10 for distributing a secondary ignition signal to the spark plugs 28 of each cylinder of the engine 10;
4 and a crank angle sensor 36 for detecting the rotational state of the engine 10 from the rotational state of the distributor shaft 34A, and a crank angle sensor 36 for detecting the engine cooling water temperature disposed in the cylinder block 70B of the engine 10. The fuel injection amount is calculated according to the engine load detected from the output of the water temperature sensor 38 and the intake pipe pressure sensor 22, the engine rotational speed determined from the output of the crank angle sensor 36, and set to the fuel injection *Jit. Calculates the required injection amount by adding air-fuel ratio feedback correction according to the deviation between the air-fuel ratio and the actual air-fuel ratio, outputs a valve opening time signal to the injector 26 to obtain the required injection amount, and executes feedback control. An electronic control unit (hereinafter referred to as EC) for learning the deviation in time and performing learning control
(referred to as U) 40.

As shown in detail in FIG. 3, the CU 40 includes a central processing unit (hereinafter referred to as CP [J]) 40A consisting of, for example, a microprocessor for performing various arithmetic processing;
A read-only memory (hereinafter referred to as ROM) 40B for storing control programs and various data, etc., and a random access memory for temporarily recording calculation data etc. input to the CPtJ 40A. (hereinafter referred to as RAM) 40G and a multiplexer function to convert analog signals input from the intake air temperature sensor 12, intake pipe pressure sensor 22, sensor 31, water temperature sensor 38, etc. into digital signals and sequentially import them. an analog-to-digital converter (hereinafter referred to as A/D converter) 40E, the throttle sensor 18, and the crank angle sensor 36.
In addition to capturing digital signals input from etc.,
40F to the input/output capo-1 (hereinafter referred to as I10 boat) equipped with a buffer function for outputting a control signal to the injector 26 etc. according to the calculation result of U40A;
It is comprised of common buses 40G and 1 for connecting the respective component devices and transferring data and instructions.

The action will be explained below.

In this embodiment, the determination as to whether the amount of change in intake pipe pressure per unit time exceeds a set value is executed by an interrupt routine at predetermined intervals as shown in FIG. That is, the process proceeds to step 110 every predetermined time period, and the intake pipe pressure P M is acquired based on the output of the ship's intake pipe pressure sensor 22. Next, the process proceeds to step 112, where the difference between the intake pipe pressure PM taken in this time and the intake pipe pressure PM taken in last time is calculated as a total n.
The change Md of intake pipe pressure per unit time is calculated by
Calculate PM. The process then proceeds to step 114, where it is determined whether the change ff1d PM is between the set values -a and b. If the determination result is negative, that is, change 11
-d When it is determined that PN2 exceeds the set value, the process proceeds to step 116, and the change fi? Skip counter C that counts the elapsed time after I PM exceeds the set value and Ic
Clear 5kip. After step 116 is completed, or if the determination result in step 114 is positive, this routine ends.

Further, the count-up of the skip counter C5kip and the determination of whether or not learning control is to be executed according to the count value are executed by a feedback control and a school gate control routine as shown in FIG. That is, first, in step 210'c, the current engine operating conditions are fed back according to, for example, the engine cold water temperature detected from the output of the water temperature sensor 38, the throttle valve opening detected from the output of the throttle sensor 18, etc. Determine whether the execution conditions are met. If the determination result is pressure, the process advances to step 212 and feedback control is executed. Next, the process proceeds to step 214, where the feedback system (
II determines whether the output of the O2 sensor 31 has reversed from rich to lean or from lean to rich. If the result/result is positive, step 2
The process proceeds to step 16, where the skip counter C5kip is incremented by one.

Next, the process proceeds to step 218, where the maximum value of the C5kip counter is guarded. After step 218 is completed, or if the determination result in step 214 is negative, the process proceeds to step 220, where it is determined whether the count value of the skip counter C5kip has exceeded a set value C1, for example, 7. If the determination result is positive, that is, if the number of inversions of the O2 sensor 31 output is equal to or greater than the set value C, and it is determined that the feedback control continues for longer than the set time, the process proceeds to step 222; Learning control is executed.On the other hand, if the determination result in step 220 is negative, that is, when it is determined that feedback control has not continued for the set time or longer after the change ad PViffi set value is exceeded, learning control is executed. This routine ends without running vttm.

In this embodiment, intake pipe pressure PM, its change mark dPM
, the feedback control value, and the state of learning control are shown in FIG. As is clear from the figure, the intake pipe pressure PM
changes and the change QdPM deviates from judgment 1 [-a, b, the number of inversions of the feedback control value becomes the judgment value (7)
Learning control is prohibited until this point is reached.

In this way, the feedback control value is disturbed,
By prohibiting learning control when the amount of change in intake pipe pressure per unit time is large, it is possible to perform learning control with higher reliability.

In this embodiment, the determination values -a, b, and c are constant values, so the program is simple.

In addition, depending on the engine operating condition, the judgment value -a,
By changing either or all of lJ and O, it is possible to achieve further optimization or simplification.

In the above embodiment, the present invention was applied to an automobile engine equipped with an electronically controlled fuel injection device 9A that senses intake pipe pressure. However, the scope of application of the present invention is not limited to this, and for example, Instead of the amount of change in pipe pressure per unit time, the present invention is implemented by determining whether or not the amount of change in intake air amount per engine revolution or the amount of change in basic injection amount per unit time exceeds a set value. The present invention can be similarly applied to automobile engines equipped with an electronically controlled fuel injection device that senses the amount of intake air, and to general electronically controlled engines.

As described above, according to the present invention, it is possible to appropriately learn the deviation between the set air-fuel ratio and the actual air-fuel ratio, and therefore it is possible to perform highly reliable learning control.

Therefore, it has the excellent effect of improving air-fuel ratio controllability, reducing exhaust emissions, and improving drivability.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the gist of the air-fuel ratio learning control method for an electronically controlled engine according to the present invention, and FIG. 2 is a flowchart showing an electronically controlled III fuel injection system using intake pipe pressure sensing, in which the present invention is adopted. FIG. 3 is a cross-sectional view, including a partial block diagram, showing the structure of an embodiment of an automobile engine equipped with an electronic engine used in the above embodiment. FIG. 4 is a block diagram showing the configuration of the IJ control unit. Similarly, FIG. 4 is a flowchart showing the time interrupt routine for counting up the skip counter. Similarly, FIG. 5 is a flow chart showing the routine for performing feedback control and learning control. The flowchart shown in FIG. 6 is a diagram showing an example of the relationship among the intake pipe pressure, the amount of change thereof per unit time, the feedback control value, and the learning control state in the embodiment. PM...Intake pipe pressure, CIPM...Amount of change in intake pipe pressure per unit time, -
a, b, c... set value, 10... engine, 22... intake pipe pressure sensor, 26... injector, 31... oxygen concentration sensor (02 sensor), 40
...Electronic control unit (ECU). Agent Takaya Ron (and 1 other person) Figure 4 Figure 5

Claims (1)

[Claims] (1) Air-fuel ratio learning control for an electronically controlled engine that performs air-fuel ratio feedback control according to the deviation between the set air-fuel ratio and the actual air-fuel ratio, and also performs learning control by learning the deviation during feedback control execution. The method includes a step of determining whether the amount of change per unit time in intake pipe pressure or intake air amount per engine revolution exceeds a set value, and a step of determining whether the amount of change exceeds the set value, and then setting again after the amount of change exceeds the set value. A procedure for determining whether feedback control continues for a set time or longer after the amount of change exceeds a set value, or when feedback control does not continue for a set time or longer. An air-fuel ratio learning control method for an electronically controlled engine characterized by comprising: a procedure for prohibiting learning control.