JP3217923B2 - Air-fuel ratio learning control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a learning control method for a learning correction value in an air-fuel ratio control method for determining a fuel injection amount based mainly on the rotational speed of an automobile engine and the opening of a throttle valve. .

[0002]

2. Description of the Related Art Conventionally, there is an air-fuel ratio control method for determining a basic fuel injection amount based on an engine speed and a throttle valve opening. As such an air-fuel ratio control method,
For example, as described in Japanese Patent Application Laid-Open No. 63-29039, the intake air amount corresponding to each operation region in which the opening degree of the throttle valve and the rotation speed of the engine are used as parameters is stored, and The opening degree and the number of revolutions are detected, a stored intake air amount corresponding to each detected value is searched, and the searched intake air amount and opening / closing of an opening / closing valve of a bypass passage bypassing the throttle valve. Alternatively, a fuel injection amount is known which is determined based on an intake air amount set according to a closed state. As described above, by taking into account the amount of intake air flowing through the bypass passage when determining the fuel injection amount, the amount of air that has entered the surge tank can be determined almost exactly to determine the fuel injection amount.

[0003]

In the above-described apparatus for determining the basic fuel injection amount based on the engine speed and the opening of the throttle valve, the intake pressure is not detected. For example, when setting a learning correction value, it is conceivable to set a learning correction value based on the engine speed and the opening of the throttle valve, such as setting the learning correction value based on the engine speed and the intake pressure. . However, when the learning correction value is set using the opening of the throttle valve as a parameter, the operating range changes with a change in the opening of the throttle valve in a region with a small opening, but the change in the opening in a large region. Changes in the operating range are small, and it may be difficult to respond. Therefore, when a learning region that defines the learning correction value is set, if the learning region is set based on the throttle valve opening and the engine speed, a sufficient learning region is set in a region where the throttle valve opening is small. Although it is possible to do so, in a region where the opening degree is large, the intake pressure does not change in accordance with the degree of the opening degree, so that a learning region cannot be preferably set.

An object of the present invention is to solve such a problem.

[0005]

In order to achieve the above object, the present invention takes the following measures. That is, in the engine air-fuel ratio learning control method according to the present invention, the bypass passage bypassing the throttle valve is provided.
The degree of opening changes continuously in this bypass passage.
A possible air flow control valve is provided and at least
Determined from engine speed and throttle valve opening
Main basic injection amount, engine speed and air flow control valve opening
A learning area defined based on the basic injection amount and the engine speed determined based on the auxiliary basic injection amount determined from the operating state of the engine, and a learning area corresponding to the operating state of the engine. Is updated, and the fuel injection amount is calculated based on at least the updated learning correction value and the basic injection amount.

[0006]

With this configuration, the learning area is
At least the engine speed and throttle valve opening
Basic injection quantity, engine speed and air flow rate determined from
By setting a basic injection amount determined based on an auxiliary basic injection amount determined based on an opening degree of a control valve and an engine speed, thereby being substantially set by an intake pressure and an engine speed. Is equivalent to That is, since the basic injection amount is determined based on the main basic injection amount and the auxiliary basic injection amount , the basic injection amount reflects the intake pressure according to the operating state. By setting the learning area based on the basic injection amount and the engine speed, the learning area is indirectly set based on the intake pressure and the engine speed. Then, the learning correction value in the learning region determined from the operating state of the engine is updated, and the fuel injection amount is calculated based on at least the learning correction value and the basic injection amount. Therefore, even when the actual change in the operating state of the engine does not follow, the update can be reliably performed in accordance with the operating state of the engine.

[0007]

An embodiment of the present invention will be described below with reference to the drawings.

The engine 100 schematically shown in FIG. 1 is for an automobile, and its intake system 1 including a surge tank 12 is shown.
Is provided with a throttle valve 2 that opens and closes in response to an accelerator pedal (not shown), and a bypass passage 3 that bypasses the throttle valve 2 is provided. An air flow control valve for controlling idle speed is provided in the bypass passage 3. A barrel flow control valve 4 is provided. The bypass passage 3 of this embodiment has an auxiliary passage 31 that bypasses the flow control valve 4, and the auxiliary passage 31 is provided with an auxiliary flow control valve 32. The flow control valve 4 is of an electronic opening / closing type, which is abbreviated as a large flow rate VSV, and controls the operating duty ratio DISC of the drive voltage applied to its terminal 4a to continuously reduce its substantial opening. The air flow rate of the bypass passage 3 can be adjusted. That is, a pair of the bypass passage 3 and the flow control valve 4 substantially unifies a bypass system path normally provided for each correction item including an increase in warm-up correction during idling operation. . The auxiliary flow control valve 32 is different from the flow control valve 4 in that
For example, it is a vacuum switching valve that opens when the control electric signal is on and closes when the control electric signal is off, and is configured to open when a relatively large load such as an air conditioner is applied. And the calculation duty ratio DIS
C is determined by adding and subtracting the water temperature correction amount DAAV, the rotation feedback (F / B) correction amount DFB, and the like, which are the warm-up correction increase amounts, including these factors.

The intake system 1 is further provided with a fuel injection valve 5, and the fuel injection valve 5 and the flow control valve 4 are controlled by an electronic control unit 6.

The electronic control unit 6 includes a central processing unit 7
, A storage device 8, an input interface 9, and an output interface 11. The main basic injection time is stored in the storage device 8 using, as parameters, a program for controlling the engine 100 and data required for calculating the injector final energization time T, such as the engine speed NE and the throttle opening TA. A first map consisting of a two-dimensional map for determining TPTA, a second map consisting of a two-dimensional map for determining the auxiliary basic injection time TPISC using the engine speed NE and the calculated duty ratio DISC as parameters, Engine speed NE
And a third map composed of a one-dimensional map for determining the on-load correction injection time TPVSV using the as a parameter. The input interface 9 has a speed signal b output from a speed sensor 14 for detecting the engine speed NE, a speed signal c output from a speed sensor 15 for detecting the speed, and a throttle valve. The opening degree signal d output from the throttle opening degree sensor 16 for detecting the opening degree TA of No. 2 and the water temperature signal e output from the water temperature sensor 17 for detecting the engine cooling water temperature as the engine temperature are input. Is done. The output interface 11 outputs a drive signal f corresponding to the calculated fuel injection time to the fuel injection valve 5 and a control signal based on a calculation duty ratio DISC to be described later to the flow control valve 4. g is output to the auxiliary flow control valve 32, respectively. Although not shown, the electronic control unit 6 has a built-in A / D converter for converting an input analog signal into digital data, and transmits an opening signal d, a water temperature signal e, and the like at regular intervals. Convert to digital data,
It is output to the central processing unit 7.

The electronic control unit 6 determines the main basic injection time TPTA using the signals from the throttle opening sensor 16 and the rotation speed sensor 14 as main information, and adds various correction amounts to the main basic injection time TPTA. Is considered, the injector final energization time T is calculated from the effective injection time TAU calculated based on the basic injection time TP, and the calculated injector final energization time T
A program for controlling the fuel injection valve 5 to inject fuel corresponding to the load from the fuel injection valve 5 to the intake system 1 is built in. For the basic injection time TP, the main basic injection time TPTA is determined based on the opening degree TA of the throttle valve 2 and the engine speed NE, and the opening degrees of the flow control valve 4 and the auxiliary flow control valve 32 are detected and detected. Flow control valve 4
And the bypass air flow rate in the bypass passage 3 based on the opening degree of the auxiliary flow control valve 32 and the engine speed NE.
Determining an auxiliary basic injection time TPISC, it is programmed to be calculated from the main basic injection time TP TA and auxiliary basic injection time TPISC. Further, the effective injection time TAU calculated on the basis of the basic injection time TP calculated in this manner is basically determined by various correction coefficients including an A / F learning value KGi as a learning correction amount set in the learning area. It is determined by correcting the correction time TP. The learning of the A / F learning value KGi is based on the basic injection time based on the opening degree TA of the throttle valve 2 and the engine speed NE.
TP is determined, the basic injection time TP and the engine speed N
This is performed by a program that sets a learning area based on E and updates a learning correction amount of the learning area according to the operating state of the engine.

A schematic configuration of the air-fuel ratio learning control and fuel injection amount calculation program is shown in FIGS.

The basic injection time TP is calculated by the following equation.

TP = TPTA (NE, TA) + TPISC (NE, DISC) * KTPTA (TPTA, DISC) + TPVSV (NE) * KTPVSV (TPTA) (1) where TPISC; engine speed NE and flow control valve 3, an auxiliary basic injection time determined by the opening degree (corresponding to the calculation duty ratio DISC), TPVSV; opening / closing (ON /
OFF) and the on-load correction injection time determined by the engine speed NE, KTPTA; main basic injection time TPTA and the flow control valve 3
KTPVSV; a slave load correction coefficient based on the main basic injection time TPTA. In this embodiment, the sum of the second and third terms in equation (1) is the corrected injection amount according to the bypass air flow rate in the bypass passage 3 described above.

The effective injection time TAU is calculated by the following equation.

TAU = TP * FAF * KGi * ETC (2) FAF; A / F feedback correction coefficient, ETC; Other correction coefficients including an intake air temperature correction coefficient, a warm-up increase correction coefficient, and the like.

The learning area KGij is, as shown in FIG.
It is defined by the basic injection time TP and the engine speed NE. In this case, as the basic injection time TP, a value calculated by the above equation (1) is adopted, and the bypass passage 3
The value takes into account the amount of air. In this example,
The entire basic injection time TP is divided into four parts, and the entire area of the engine speed NE is divided into four parts, so that the operating range of the engine is reduced to 16
And the learning area KGij is set in the storage device 8 in the form of a two-dimensional map. A / F learning values KG1 to KG16 are set in each of the learning areas KGij.

When the engine is in an idling state,
The fuel injection amount is determined by the following procedure, and the fuel injection control is performed. First, in step P1, the basic injection time TP
Is calculated. The basic injection time TP is calculated by the above equation (1). Details will be described later with reference to the drawings. In Step P2, various correction coefficients according to the operating state of the engine at this time are calculated. That is, if the operation state is after the start, the post-start increase correction coefficient and the warm-up increase correction coefficient are calculated, and if the fuel supply is to return from the fuel cut, the fuel cut return correction coefficient and the same increase correction coefficient are calculated. Step P3
Then, the A / F learning value KG is calculated. The A / F learning value KG is the A / F learning value KGi stored in each learning area KGij, for example, the A / F learning value KGij of the learning area KGij.
It is calculated by adding to the average value of the F learning value KGi. In step P4, the effective injection time TAU is calculated using the various correction coefficients and the A / F learning value KG calculated in step P2, and the fuel injector 5 is controlled by the calculated injector final energization time T. Execute fuel injection.

The calculation of the basic injection time TP is as follows. First, in step S1, the main basic injection time TPTA is determined by performing four-point interpolation on the first map from the engine speed NE and the throttle opening TA. That is, the engine speed NE is detected, it is determined which engine speed region the detected engine speed NE belongs to in the first map, and the throttle opening TA
Is determined, and to which of the opening areas set by the two points on the first map the detected throttle opening TA belongs is determined, and the area defined by both the rotation speed area and the opening area is determined. The set value is adopted as the current main basic injection time TPTA. Thereafter, in step S2, similarly,
Based on the engine speed NE and the calculation duty ratio DISC, four-point interpolation is performed on the second map to determine the auxiliary basic injection time TPISC. The method of four-point interpolation in this step is the same as that in step S1.

When the main basic injection time TPTA and the auxiliary basic injection time TPISC are determined in this way, in step S3, the state of the load at that time is determined from the value of the main basic injection time TPTA, and the determined magnitude of the load is determined. The main load correction coefficient KTPTA which is increased or decreased according to the above is calculated. Further, in order to determine the air flow rate in the auxiliary passage 31, in step S4, the on-load correction injection amount TPVSV is determined from the engine speed NE at this time by interpolating the third map. In step S5, as in step S3, a slave load correction coefficient KTPVSV is calculated in accordance with the magnitude of the load determined from the master basic injection time TPTA.

Next, at step S6, the basic injection time TP
The main basic injection time TPTA is temporarily stored, and in step S7, a value obtained by multiplying the basic injection time TP by the main load correction coefficient KTPTA to the auxiliary basic injection time TPISC is newly stored as the basic injection time. . Thus, the main basic injection time TPTA and the main load correction coefficient K
Auxiliary basic injection time TPISC corrected by TPTA
The amount of air sucked into the surge tank 12 via the throttle valve 2 and the flow control valve 4 is determined by the sum of the air flow rate and the remaining air amount sucked through the auxiliary flow control valve 32 in step S8. It is determined whether the auxiliary flow control valve 32 is open or not based on whether or not the auxiliary flow control valve 32 is open. If the auxiliary flow control valve 32 is open, the process proceeds to step S9. If the auxiliary flow control valve 32 is closed, the routine ends without any change. If the auxiliary flow control valve 32 is open, in step S9, the basic injection time TP stored at this time is added to the on-load correction injection time T
A final basic injection time TP when a load is applied is calculated by multiplying the load correction coefficient KTPVSV according to the PVSV and then adding the result.

Next, in order to update the A / F learning value KGi, in step K1, the division of the basic injection time TP in the learning area KGij is determined from the operating state of the engine at this time. In step K2, the classification of the engine speed NE in the learning area KGij is determined. In step K3, a learning area KGij is determined from the determined division of the basic injection time TP and the engine speed NE. A / F
The calculation method for updating the learning value KGi may use a method widely known in this field. As an example, first, every time the A / F feedback correction coefficient FAF is skipped, that is, every time the A / F feedback correction coefficient FAF is instantaneously switched when the air-fuel ratio changes from lean to rich or from rich to lean, immediately before the previous skip. The arithmetic mean of the value and the value immediately before the current skip is obtained. Then, the learning area KGi is determined by the operating state of the engine.
j, the A / F feedback correction coefficient F
Each time the AF is skipped, the learning area K is determined based on the magnitude of the arithmetic mean.
The A / F learning value KGi of Gij is increased or decreased, and the obtained value is stored until the next update.

If the engine is idling and there is no heavy load such as an air conditioner, the control proceeds to steps S1 to S7, and after step S8, the control proceeds to another routine. In this case, the basic injection time TP is determined by the engine speed NE and the throttle opening TA.
It is determined based on TA and the auxiliary basic injection time TPISC determined by the engine speed NE and the calculated duty ratio DISC which is the opening of the flow control valve 4 in the bypass passage 3. Conversely, if air conditioning is used,
Since it is necessary to idle up by that amount, the auxiliary flow control valve 32 is opened, and therefore, the control proceeds to step S1.
Proceed to ~ 9. In this case, by executing steps S7 and S9, the basic injection time TP is calculated by the above equation (1).

The A / F learning value KGi is calculated when the learning timing is reached during the feedback control operation.
The control proceeds to steps K1 to K4, where a learning region KGij is determined from the basic injection time TP calculated under the respective load conditions at that time and the engine speed NE at that time, and the learning region KGij is determined by a predetermined calculation. A / F
The learning value KGi is updated.

As described above, the auxiliary basic injection time TPISC determined based on the engine speed NE and the opening degree (calculated duty ratio DISC) of the flow control valve 4 and the engine speed NE when the engine is open are shown. The on-load correction injection time TPVSV determined by
The main correction injection time TPTA is corrected based on the load state at that time, and the corrected auxiliary basic injection time TPISC and the load correction injection time TPVSV are corrected.
Therefore, the amount of intake air in the bypass passage 3 can be calculated in a state in which the operating state of the engine 100 is reflected, and the air-fuel ratio can be prevented from becoming lean. In addition, by determining the auxiliary injection amount in accordance with the engine speed with respect to the intake air amount passing through the bypass passage bypassing the throttle valve, the inflow air amount always flowing into the surge tank and the fuel injection amount can be determined. Accordingly, it is possible to prevent the air-fuel ratio from becoming lean, and it is possible to reliably exhibit good drivability.

Since the A / F learning value KGi is set in a learning region KGij defined based on the engine speed NE and the basic injection time TP, the learning region KGij substantially reflects the intake pressure. Can be learned, and the deviation of the fuel injection amount can be easily corrected. Further, even if the air amount passing through the bypass passage 3 changes, including during the idling operation, the change is included in the basic injection time TP, so that the accuracy of the A / F learning value KGi does not decrease.

The present invention is not limited to the embodiment described above. For example, the bypass passage 3 does not need to have the auxiliary passage 31 and is configured to respond to various loads including the air conditioner by controlling the opening degree of the flow control valve 4. There may be.
That is, when calculating the calculation duty ratio DISC,
A program is configured so that the basic amount is corrected according to the load of the air conditioner, headlight, defogger, etc., and the opening of the flow control valve 4 is made to correspond to the load.
In calculating the basic injection amount TP, the following equation (1) in the above embodiment is used: ΔTPVSV (NE) * KTPVSV
(TPTA) The configuration may be such that the｝ term is deleted. Therefore, in the program, step S in the flowchart shown in FIG.
Steps 4 and 5 and steps S8 and 9 may be deleted. In addition,
In such another embodiment, the main basic injection time TPTA, the auxiliary basic injection time TPISC and the like are of course set to values different from those in the above embodiment.

In the above embodiment, the main load correction coefficient K
Although the TPISC is calculated according to the fuel cut size determined from the main basic injection time TPTA, it is determined based on a two-dimensional map using the main basic injection time TPTA and the calculated duty ratio DISC as parameters. Is also good. In this way, by taking into account the calculation duty ratio DISC in determining the main load correction coefficient KTPISC,
The load state can be more accurately reflected on the main load correction coefficient KTPISC.

In addition, the configuration of each section is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0030]

According to the present invention, as described in detail above, the learning area is defined by at least the engine speed and the throttle valve.
The main basic injection amount determined from the opening and the engine speed
Auxiliary basic injection amount determined from the opening of the air flow control valve
And the basic injection amount and the engine speed determined based on
And the learning correction value is updated, so that the learning correction value can be updated in an accurate learning region. Therefore, it is possible to suppress the careless updating of the learning correction value in the learning region different from the actual driving state, and it is possible to increase the updating accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic configuration explanatory view showing one embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of the embodiment.

FIG. 3 is a flowchart showing a control procedure of the embodiment.

FIG. 4 is a configuration explanatory diagram showing a learning area according to the embodiment.

[Explanation of symbols]

 2 ... Throttle valve 3 ... Bypass passage 4 ... Flow control valve 6 ... Electronic control device 7 ... Central processing unit 8 ... Storage device 9 ... Input interface 11 ... Output interface

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-213635 (JP, A) JP-A-2-286848 (JP, A) JP-A-2-78747 (JP, A) JP-A-63-1988 29039 (JP, A) Japanese Utility Model Hei 1-76536 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 41/14 310

Claims (1)

(57) [Claims] 1. A bypass passage bypassing a throttle valve.
Is provided, and the opening degree is continuously
A variable air flow control valve is provided.
Is determined from the engine speed and the throttle valve opening.
Of the main basic injection amount, engine speed and air flow control valve
A learning region defined based on the basic injection amount determined based on the opening degree and the auxiliary basic injection amount and the engine speed is determined from the operating state of the engine. An air-fuel ratio learning control method, comprising: updating a learning correction value in a learning region; and calculating a fuel injection amount based on at least the updated learning correction value and the basic injection amount.