JPH01305146A - Air fuel ratio learning controller of internal combustion engine - Google Patents

Abstract

PURPOSE:To restrict step differences in an air-fuel ratio regardless of existence of any external load by advancing the second learning conforming to an increase in an external load after progress of the first learning per area relating to scatter, etc., of various kinds of part. CONSTITUTION:A basic fuel supply quantity is set up by means (b) on the basis of engine running condition detected by a means (a). And, a feedback correction factor is set up by a means (d) on the basis of an air-fuel ratio detected by a means (c). Further, when existence of no external load is detected by a means (e), the first learning correction factor of the basic fuel supply quantity stored in a means (f) is corrected by a means (g). On the other hand, when existence of an external load is detected by a means (e) and the progressing grade of learning detected by a means (h) is more than the prescribed value, the second learning correction factor stored in a means (i) is corrected by a means (i). Then, a fuel supply quantity is set up by a means (m) or the basis of the total learning correction factor set up by a means (l), and also the set quantity of fuel is supplied to an engine by a means (n).

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an air-fuel ratio learning control device for an internal combustion engine that has an electronically controlled fuel supply device with an air-fuel ratio feedback control function, and particularly relates to an air-fuel ratio learning control device for an internal combustion engine that has an electronically controlled fuel supply device with an air-fuel ratio feedback control function. A learning system for the air-fuel ratio in an internal combustion engine that increases the amount of air that bypasses the intake throttle valve and increases the output when the intake throttle valve is applied. The present invention relates to a device having enhanced functions.

<Prior Art> Conventionally, in an internal combustion engine having an electronically controlled fuel supply device with an air-fuel ratio feedback control function,
An air-fuel ratio learning control device as shown in Japanese Patent No. 190141 is employed.

This is a feedback correction that sets the basic fuel supply amount calculated from the intake air flow rate and engine speed using proportional-integral control etc. based on the air-fuel ratio detection signal from the 0□ sensor installed in the engine's exhaust system. In a device that calculates the fuel supply amount by correcting it using a coefficient and controls the air-fuel ratio to the target air-fuel ratio using a feedback correction coefficient, the deviation from the reference value of the feedback correction coefficient during the air-fuel ratio feedback control is calculated based on a predetermined engine operating state. A learning correction coefficient is determined for each area. When setting the fuel supply amount, the basic fuel supply amount is corrected by the learning correction coefficient to aim for a base air-fuel ratio obtained by the fuel supply amount calculated without correction by the feedback correction coefficient. This is made to match the air-fuel ratio, and during air-fuel ratio feedback control, this is further corrected using a feedback correction coefficient to calculate the fuel supply amount.

According to this, it is possible to eliminate the follow-up delay of the feedback control during the transient operation during the air-fuel ratio feedback control, and it is possible to accurately obtain the desired air-fuel ratio when the air-fuel ratio feedback control is stopped.

On the other hand, when a large external load such as an air conditioner is applied,
It has become common to open a fast idle control valve installed in a passage that bypasses the throttle valve to increase the flow rate of bypass air and increase the amount of fuel supplied accordingly, thereby increasing output. There is.

In an internal combustion engine using such a fast idle control valve material, when an external load is applied and the fast idle control valve opens, a second learning correction coefficient that is set separately from the learning correction coefficient for each area is applied to the same area. At the same time, the detected value of the intake air flow rate at that time is stored, and the second learning correction coefficient is adjusted to the ratio of the stored detected value to the current detected value of the intake air flow rate. There is a system in which the value added to the learning correction coefficient of is set as the total learning correction coefficient.

With this, even if the first idle control valve is opened during idle and the intake air flow rate changes significantly, the learning function using the second learning correction coefficient can suppress changes in the air-fuel ratio.

<Problems to be Solved by the Invention> By the way, in the above-mentioned device in which learning is performed using a dedicated second learning correction coefficient for increasing external load,
If the second learning correction coefficient is learned in advance before learning of the first learning correction coefficient that corresponds to parts variations in each area, etc., during said learning, parts variations etc. Since the learning correction coefficient for each area is corrected by learning both the increase in air flow rate and the increase in bypass air flow rate, the learning correction coefficient for each area is
The learning correction coefficient of is reversely corrected in the direction of removing the correction amount due to component variations.

Therefore, in areas where there are few learning opportunities for the first learning correction coefficient, the correction of the first learning correction coefficient corresponding to the learning of the second learning correction coefficient does not proceed, resulting in a difference in the air-fuel ratio. Driving performance may be impaired, and fuel efficiency, exhaust characteristics, etc. may also deteriorate.

The present invention was developed in view of such conventional problems, and after the first learning corresponding to component variations etc. has progressed to a certain extent, learning for when external load increases is performed.
It is an object of the present invention to provide an air-fuel ratio learning control device for an internal combustion engine that solves the above problems.

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention opens an air passage that bypasses the intake throttle valve of the engine to reduce intake air when an external load of a predetermined value or more is applied. In an internal combustion engine in which the flow rate is increased, the engine operating state detection means detects the engine operating state, the air-fuel ratio detection means detects the air-fuel ratio of the engine intake air-fuel mixture, and the engine operating state detection means detects the air-fuel ratio of the engine intake air-fuel mixture. a basic fuel supply amount setting means for setting a basic fuel supply amount based on the operating state; and a comparison between the air-fuel ratio detected by the air-fuel ratio detection means and a target air-fuel ratio, and bring the actual air-fuel ratio closer to the target air-fuel ratio. a feedback correction coefficient setting means for increasing or decreasing a feedback correction coefficient by a predetermined amount for correcting the basic fuel supply amount; and a first feedback correction coefficient setting means for correcting the basic fuel supply amount for each area of the engine operating state. rewritable first learning correction coefficient storage means that stores a learning correction coefficient; external load detection means that detects the presence or absence of the external load; and a reference value of the feedback correction coefficient when the external load is not applied. Based on the amount of deviation from the first
a first learning correction coefficient correction means for correcting and rewriting the first learning correction coefficient in the area of the engine operating state stored in the learning correction coefficient storage means; learning progress detecting means for detecting the progress of corrective learning; and a rewritable second learning device that stores a second learning correction coefficient for correcting the basic fuel supply amount when the external load is applied. correction coefficient storage means; when the external load is applied and the learning progress of the first learning correction coefficient detected by the learning progress detection means reaches a predetermined value or more, the second learning correction coefficient storage means; a second learning correction coefficient correction means for correcting and rewriting a second learning correction coefficient stored in the means based on the amount of deviation of the feedback correction coefficient from a reference value; and during correction by the second learning correction coefficient correction means. an intake air flow rate detection value storage means for storing a detected value of the intake air flow rate; and a second latest learning correction coefficient stored in the second learning correction coefficient storage means.
The value set based on the learning correction coefficient and the ratio of the detected value stored in the intake air flow rate storage means to the current detected value of the intake air flow rate is set to the latest first learning correction coefficient stored in the first learning correction coefficient storage means. total learning correction coefficient setting means for setting a value added to the learning correction coefficient as a total learning correction coefficient; and the basic fuel supply amount set by the basic basic fuel supply amount setting means and the feedback set by the feedback correction coefficient setting means. a fuel supply amount setting means for setting a fuel supply amount based on a correction coefficient and a total learning correction coefficient set by the total learning correction coefficient setting means; and supplying the engine with the amount of fuel set by the fuel supply amount setting means. and a fuel supply means for supplying fuel.

<Operation> The basic fuel supply amount setting means sets the basic fuel supply amount according to the detected engine operating state, and the feedback correction coefficient setting means converts the actual air-fuel ratio detected by the air-fuel ratio detection means into the target air-fuel ratio. The feedback correction coefficient is set by increasing or decreasing a predetermined amount based on, for example, proportional-integral control so as to approximate the fuel ratio.

On the other hand, when the external load detection means detects that a large external load such as an air conditioner that increases the bypass air flow rate in a stepwise manner is not applied, the first learning correction coefficient correction means performs the first learning correction. The first learning correction coefficient for the driving state area stored in the coefficient storage means is corrected and rewritten based on the deviation amount of the set feedback correction coefficient from the reference value.

Further, when it is detected that the external load is not applied, the first
When the learning progress of the learning correction coefficient has reached a predetermined level or more, the second learning correction coefficient correction means stores the feedback correction coefficient in the second learning correction coefficient storage means based on the amount of deviation from the reference value of the feedback correction coefficient. At the same time as correcting and rewriting the second learning correction coefficient, the intake air flow rate storage means stores the detected value of the intake air flow rate at this time.

Then, the total learning correction coefficient setting means sets the latest second learning correction coefficient stored in the second learning correction coefficient storage means and the detected value stored in the intake air flow rate storage means with respect to the current detected value of the intake air flow rate. The value set based on the ratio is set based on the latest first learning correction coefficient stored in the first learning correction coefficient storage means.
The value added to the learning correction coefficient is set as the total learning correction coefficient.

The fuel supply amount setting means sets the fuel supply amount based on the basic fuel supply amount, the feedback correction coefficient, and the total learning correction coefficient each set as described above, and the fuel supply means sets the fuel supply amount based on the set amount. of fuel is supplied to the engine.

<Example> An embodiment of the present invention will be described below based on the drawings.

FIG. 2 shows the configuration of an embodiment device according to the present invention.

In the figure, an internal combustion engine 1 includes an air cleaner 2°, an intake duct 3. Throttle chamber 4 and intake manifold 5
Air is supplied through.

The intake duct 3 is provided with an air flow meter 6 that detects the intake air flow rate Q.

The throttle chamber 4 is provided with a throttle valve 7 that operates in conjunction with an accelerator pedal (not shown) to control the intake air flow rate Q.

The intake manifold 5 is provided with an electromagnetic fuel injection valve 8 as a fuel supply means for each cylinder, and is driven to open by an injection pulse signal from a control unit 10 containing a microcomputer, which will be described later. The fuel pumped under pressure from the fuel pump is injected and supplied into the intake manifold 5.

Further, a water temperature sensor 11 is provided to detect the cooling water temperature Tw in the cooling jacket of the engine, and an exhaust passage 1
Turns ON or OFF whether the air-fuel ratio is larger or smaller than the target air-fuel ratio (theoretical air-fuel ratio) by detecting the oxygen concentration in the exhaust gas in 2.
An oxygen sensor 13 is provided as an air-fuel ratio detection means for detecting the air-fuel ratio.

Further, a bypass passage 15 is provided which bypasses the throttle valve 7 and has a fast idle control valve 14 interposed therein, and the fast idle control valve 14 is opened when an external load of more than a predetermined value, such as an air conditioner, is applied. By increasing the bypass air flow rate, it is possible to increase the output commensurate with the magnitude of the external load.

The control unit 10 detects the engine rotation speed N by counting the crank angle unit signal output from the crank angle sensor 16 in synchronization with the engine rotation for a certain period of time or by measuring the period of the crank angle reference signal. .

In addition to the crank angle sensor 16, signals from the various sensors (these constitute engine operating state detection means) are input to the control unit IO, and ON/OFF signals of the air conditioner switch 17 are input. , based on these detection signals, the fuel supply amount T is set to drive the fuel injection valve 8 and control the opening/closing of the fast idle control valve 14, etc. Here, when setting the fuel supply amount T+, learning control according to the present invention is performed.

This learning control routine will be explained according to the flowchart in FIG. In this learning, the operating state is the engine speed N and the basic fuel supply amount T, which is set as described later, in order to store the first learning correction coefficient.

This is done every time the signal from the oxygen sensor 13 inverts after entering a certain area divided by the parameters .

In step 1 (denoted as S in the figure), the oxygen sensor 1
It is determined whether the detection signal No. 3 has been inverted a predetermined number of times.

If the number of reversals is less than the predetermined value, the process advances to step 2, where the reference value α of the air-fuel ratio feedback correction coefficient α is set by the fuel supply amount setting routine described later at the time of reversal.
. The deviation Δα from Δα is temporarily stored as Δα1.

On the other hand, when it is determined in step 1 that the number of reversals has reached the predetermined value, the process proceeds to step 3, where the reference value α of the feedback correction coefficient α of the air-fuel ratio at the time of the reversal is determined. deviation from Δ
Assuming that α is Δα3, the average value with the deviation amount Δα1 is calculated by the following equation.

17 ON/OFF judgment is performed. That is, the air conditioner switch 17 and the function of step 4 constitute an external load detection means that detects the presence or absence of an external load of a predetermined value or more.

If it is determined to be OFF, the process proceeds to step 5, where the microcomputer RAM is searched for the first learning correction coefficient KLI of the area in the current operating state, and the first learning correction coefficient KLI is stored in the RAM of the microcomputer in step 3. A new first learning correction coefficient KLI is calculated by adding a value obtained by multiplying the average value of the calculated deviation amounts by a predetermined ratio of 1/M. That is, the RAM that stores the first learning correction coefficient KLI as a map constitutes a first learning correction coefficient storage means.

Next, the process proceeds to step 6, where the new first learning correction coefficient KLI is used to determine the first learning correction coefficient KL for the same area.
Correct and rewrite the data in I. That is, step 5,
The function No. 6 corresponds to the first learning correction coefficient correction means.

Further, the process proceeds to step 7, and each time the first learning correction coefficient KLI is corrected as described above, the first learning correction coefficient KLI
The value of a counter L, which represents the progress of learning, is counted up. That is, this counter L corresponds to learning progress detection means.

-4. When it is determined in step 4 that the air conditioner switch 17 is ON, the process proceeds to step 8, and it is determined whether the value of the counter L has reached a predetermined value L0.

When it is determined that it is less than the predetermined value, this routine is ended, but when it is determined that it is greater than or equal to the predetermined value, the process proceeds to step 9, where the second learning correction coefficient KLt stored in the RAM is searched, Similar to the learning of the first learning correction coefficient KLI, the second learning correction coefficient KL! A new second learning correction coefficient KLt is calculated by adding a value obtained by multiplying the average value τi of the deviation amount by a predetermined ratio 1/M''.

In step 10, the new second learning correction coefficient KL!
Then, the current intake air flow rate detection value Q detected by the air flow meter 6 is stored as Qo. That is, R
AM corresponds to second learning correction coefficient storage means, step 9 and step 10 correspond to second learning correction coefficient correction means, and RA, M and step 10 constitute intake air flow rate storage means.

Next, the fuel supply amount setting routine will be explained according to the flowchart shown in FIG.

In step 11, a basic fuel supply amount T is calculated based on the intake air flow rate Q detected by the air flow meter 6 and the engine speed N detected by the crank angle sensor 16. The function of step 11 corresponds to basic fuel supply amount setting means.

In step 12, various correction coefficients C0EF are set based on the water temperature Tw, etc., as necessary.

In step 13, the first learning correction coefficient KLI of the latest corresponding area stored in the RAM is retrieved from the engine rotational speed N representing the engine operating state and the basic fuel supply amount T.

In step 14, a voltage correction numerator is set based on the voltage value of the battery.

In step 15, it is determined whether the λ control condition is met.

Here, for example, high rotation, which is not under 15 control conditions,
In the case of a high load area, etc., step 1 is performed with the feedback correction coefficient α clamped to the previous value (or reference value).
5, the process proceeds to step 20, which will be described later.

In the case of the λ control condition, in steps 16 to 18, the output voltage of the oxygen sensor 13 is compared with a slice level voltage corresponding to the target air-fuel ratio (theoretical air-fuel ratio) to determine whether the air-fuel ratio is rich or lean, and integral control is performed. Alternatively, the feedback correction coefficient α is set by proportional-integral control. That is, steps 16 to 18 correspond to feedback correction coefficient setting means.

Specifically, in the case of integral control, when the comparison in step 16 determines that the air-fuel ratio is -rich, in step 17 the feedback correction coefficient α is set by a predetermined integral value with respect to the previous value! Conversely, when it is determined that the air-fuel ratio is lean, the feedback correction coefficient α is increased by a predetermined integral I with respect to the previous value in step 18.

Next, in step 19, a total learning correction coefficient Kt is calculated using the following equation from the latest first learning correction coefficient KLI and second learning correction coefficient KLt stored in the RAM and the intake air flow rate Q0. That is, the function of step 19 corresponds to total learning correction coefficient setting means.

KL - KLI + Ktz·Qo /Q Thereafter, in step 20, the final calculation is performed according to the fuel injection amount T1. That is, the function of step 20 corresponds to fuel supply amount setting means.

T+”=Tr −COE F−KL・α+T.

When the fuel injection amount T is set in this way, that T
A drive pulse signal having a pulse width of , is output at a predetermined timing in synchronization with engine rotation, and a set amount of fuel is injected and supplied from the fuel injection valve 8.

In this way, after learning of the first learning correction coefficient KLI for correcting the deviation of the air-fuel ratio from the base air-fuel ratio due to variations in the air flow meter 6 or fuel injection valve 8 for each area has progressed, the learning of the second learning correction coefficient KLI is performed. In order to start learning the learning correction coefficient KLt, the second learning correction coefficient KL2 can learn the air-fuel ratio deviation due only to the increase in the bypass air flow rate, so the learning of the first learning correction coefficient KLI has sufficiently progressed. It is possible to suppress the occurrence of differences in the air-fuel ratio in areas where there is no fuel consumption, thereby improving driving performance, fuel efficiency, and exhaust characteristics.

In this embodiment, the learning progress of the first learning correction coefficient KLI is detected as a total value in all driving regions, but since the learning progress differs depending on the area, the learning progress is determined for each area. is detected and the second learning correction coefficient KL
If the method of 2 starts learning, more accurate control can be achieved.

Also, the second learning correction coefficient KL for all learning! It is also possible to adopt a method in which the rate of learning is kept below a predetermined value.

In this example, the fuel supply amount is controlled by directly detecting the intake air flow rate, but there are other methods that control the fuel supply amount based on the throttle valve opening, intake pressure, and engine speed. In the control device, the present invention can be applied by estimating the intake air flow rate from these parameters for controlling the fuel supply amount.

<Effects of the Invention> As explained above, according to the present invention, the first
Since the second learning is performed in accordance with the increase in external load after the learning of Therefore, it is possible to suppress the difference in air-fuel ratio regardless of the presence or absence of an external load, and it is possible to improve driving performance, fuel efficiency, and exhaust characteristics.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a diagram showing the configuration of an embodiment of the present invention, FIG. 3 is a flowchart showing the learning control routine of the same embodiment, and FIG. 4 is a fuel It is a flowchart which shows a supply amount setting routine. ■...Internal combustion engine 6...Air flow meter 7...
・Throttle valve 8...Fuel injection valve 10...
Control unit 13 River oxygen sensor 14.
...Fast idle control valve 15 ... Bypass passage 16 ... Crank angle sensor Patent applicant Japan Electronics Co., Ltd. Representative Patent attorney Fujio Sasashima Figure 4

Claims (1)

[Claims] In an internal combustion engine, an air passage bypassing an intake throttle valve of the engine is opened to increase the intake air flow rate when an external load of a predetermined value or more is applied, and the engine operating state is detected. An engine operating state detecting means; an air-fuel ratio detecting means for detecting an air-fuel ratio of an engine intake air-fuel mixture; and a basic fuel supply amount setting for setting a basic fuel supply amount based on the operating state detected by the engine operating state detecting means. and a feedback correction coefficient for comparing the air-fuel ratio detected by the air-fuel ratio detection means with a target air-fuel ratio and correcting the basic fuel supply amount so as to bring the actual air-fuel ratio closer to the target air-fuel ratio. a feedback correction coefficient setting means for increasing or decreasing the amount of the fuel; and a rewritable first learning correction coefficient storage means for storing a first learning correction coefficient for correcting the basic fuel supply amount for each area of the engine operating state. , external load detection means for detecting the presence or absence of the external load;
a first learning correction coefficient correction means for correcting and rewriting the first learning correction coefficient in the area of the engine operating state stored in the learning correction coefficient storage means; learning progress detecting means for detecting the progress of corrective learning; and a rewritable second learning device that stores a second learning correction coefficient for correcting the basic fuel supply amount when the external load is applied. correction coefficient storage means; when the external load is applied and the learning progress of the first learning correction coefficient detected by the learning progress detection means reaches a predetermined value or more, the second learning correction coefficient storage means; a second learning correction coefficient correction means for correcting and rewriting a second learning correction coefficient stored in the means based on the amount of deviation of the feedback correction coefficient from a reference value; and during correction by the second learning correction coefficient correction means. an intake air flow rate detection value storage means for storing a detected value of the intake air flow rate; and a second latest learning correction coefficient stored in the second learning correction coefficient storage means.
The value set based on the learning correction coefficient and the ratio of the detected value stored in the intake air flow rate storage means to the current detected value of the intake air flow rate is set to the latest first learning correction coefficient stored in the first learning correction coefficient storage means. total learning correction coefficient setting means for setting a value added to the learning correction coefficient as a total learning correction coefficient; and the basic fuel supply amount set by the basic basic fuel supply amount setting means and the feedback set by the feedback correction coefficient setting means. a fuel supply amount setting means for setting a fuel supply amount based on a correction coefficient and a total learning correction coefficient set by the total learning correction coefficient setting means; and supplying the engine with the amount of fuel set by the fuel supply amount setting means. 1. An air-fuel ratio learning control device for an internal combustion engine, comprising: a fuel supply means for controlling the air-fuel ratio;