JPH0686831B2 - Air-fuel ratio learning controller for internal combustion engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to an air-fuel ratio learning control device for an internal combustion engine having an electronically controlled fuel supply device having an air-fuel ratio feedback control function, and particularly to a large external load such as an air conditioner. The present invention relates to a device for increasing the learning control function of the air-fuel ratio in an internal combustion engine that increases the output by increasing the amount of air that bypasses the intake throttle valve when is added.

<Prior Art> Conventionally, in an internal combustion engine having an electronically controlled fuel supply device having an air-fuel ratio feedback control function, Japanese Patent Laid-Open No. 61-19
An air-fuel ratio learning control device as disclosed in Japanese Patent No. 0141 is adopted.

This is a feedback correction that sets the basic fuel supply amount calculated from the intake air flow rate and the engine speed based on the air-fuel ratio detection signal from the O ₂ sensor installed in the exhaust system of the engine by proportional integral control, etc. The fuel supply amount is calculated by correcting with a coefficient, and the air-fuel ratio is controlled by the feedback correction coefficient to the target air-fuel ratio.In the air-fuel ratio feedback control, the deviation from the reference value of the feedback correction coefficient of the engine operating state that is predetermined When setting the learning correction coefficient for each area and setting the fuel supply amount, the basic fuel supply amount is corrected by the learning correction coefficient, and the base air-fuel ratio obtained by the fuel supply amount calculated without correction by the feedback correction coefficient is targeted. Match with the air-fuel ratio, and during air-fuel ratio feedback control, this is further corrected by the feedback correction coefficient. It is intended for calculating the fuel supply amount Te.

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,
By opening the fast idle control valve provided in the passage that bypasses the throttle valve, the bypass air flow rate is increased, and the fuel supply amount is also increased accordingly. There is.

Then, in such an internal combustion engine with a fast idle control valve, when an external load is applied and the fast idle control valve is opened, a second learning correction coefficient set separately from the learning correction coefficient for each area is the same. In addition to performing correction learning by the method, the detected value of the intake air flow rate at that time is stored, and the second learning correction coefficient is set to the first detected amount of the detected value of the current intake air flow rate. There is a method in which the value added to the learning correction coefficient is set as the total learning correction coefficient.

With this configuration, even when the fast idle control valve is opened and the intake air flow rate changes significantly during idling, the learning function based on the second learning correction coefficient can suppress the change in the air-fuel ratio.

<Problems to be Solved by the Invention> By the way, in the case where learning is performed using the second learning correction coefficient dedicated for increasing the external load as described above,
If the second learning correction coefficient is learned prior to the learning of the first learning correction coefficient corresponding to the area-specific part variation, etc. The learning correction coefficient for each area is the second
The learning correction coefficient is inversely corrected in the direction in which the correction by the component variation is removed.

Therefore, in the area where the chances of learning the first learning correction coefficient are small, the correction of the first learning correction coefficient corresponding to the learning of the second learning correction coefficient does not proceed, resulting in a step difference in the air-fuel ratio. Driving performance was impaired, and fuel efficiency and exhaust characteristics were sometimes deteriorated.

The present invention has been made in view of the above-mentioned conventional problems, and the above problems are solved by performing learning for increasing the external load after the first learning corresponding to the variation in parts has progressed to some extent. It is an object of the present invention to provide a solved air-fuel ratio learning control device for an internal combustion engine.

<Means for Solving the Problems> Therefore, according to the present invention, as shown in FIG. 1, when an external load of a predetermined amount or more is applied, the intake passage is opened by opening the air passage bypassing the intake throttle valve of the engine. In an internal combustion engine configured to increase the flow rate, the engine operating state detecting means for detecting the engine operating state, the air-fuel ratio detecting means for detecting the air-fuel ratio of the engine intake air-fuel mixture, and the engine operating state detecting means are detected. The basic fuel supply amount setting means for setting the basic fuel supply amount based on the operating state and the air-fuel ratio detected by the air-fuel ratio detecting means and the target air-fuel ratio are compared to bring the actual air-fuel ratio close to the target air-fuel ratio. Feedback correction coefficient setting means for setting the feedback correction coefficient for correcting the basic fuel supply amount by increasing or decreasing by a predetermined amount, and the basic correction for each area of the engine operating state. A rewritable first learning correction coefficient storage unit that stores a first learning correction coefficient for correcting the fuel supply amount, an external load detection unit that detects the presence or absence of the external load, and the external load is not added. Sometimes, based on the deviation amount from the reference value of the feedback correction coefficient, the first
A first learning correction coefficient correction unit that corrects and rewrites the first learning correction coefficient stored in the learning correction coefficient storage unit in the area of the engine operating state; and a first learning correction coefficient by the first learning correction coefficient correction unit. Learning progress detection means for detecting the progress of correction learning, and rewritable second learning storing a second learning correction coefficient for correcting the basic fuel supply amount when the external load is applied. Correction coefficient storage means, the second learning 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. Second learning correction coefficient correction means for correcting and rewriting the second learning correction coefficient stored in the means based on a deviation amount of the feedback correction coefficient from a reference value; and the second learning correction coefficient. An intake air flow rate detected value storage means for storing a detected value of the intake air flow rate at the time of correction by the positive coefficient correction means, and a latest second stored in the second learning correction coefficient storage means.
The latest first learning stored in the first learning correction coefficient storage means is a 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. Total learning correction coefficient setting means for setting the added value to the correction coefficient as a total learning correction coefficient, basic fuel supply amount set by the basic basic fuel supply amount setting means, feedback correction set by the feedback correction coefficient setting means Coefficient, fuel supply amount setting means for setting the fuel supply amount based on the total learning correction coefficient set by the total learning correction coefficient setting means, and the amount of fuel set by the fuel supply amount setting means for supplying to the engine And a fuel supply means.

<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 sets the actual air-fuel ratio detected by the air-fuel ratio detecting means to the target air-fuel ratio. The feedback correction coefficient is set to be increased or decreased by a predetermined amount based on, for example, proportional-plus-integral control so as to approach the fuel ratio.

On the other hand, when the external load detection means detects that a large external load that increases the bypass air flow rate such as the air conditioner stepwise is not applied, the first learning correction coefficient correction means causes the first learning correction The first learning correction coefficient of the operating state area stored in the coefficient storage means is modified 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 learning progress detecting means detects 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 learning correction coefficient in the second learning correction coefficient storage means based on the deviation amount from the reference value of the feedback correction coefficient. At the same time as the second learning correction coefficient is corrected and rewritten, the intake air flow rate storage means stores the detected value of the intake air flow rate at this time.

Then, by the total learning correction coefficient setting means, the latest second learning correction coefficient stored in the second learning correction coefficient storage means and the detection value stored in the intake air flow rate storage means with respect to the current detection value of the intake air flow rate The value set based on the ratio and the latest first correction value 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 on the basis of the basic fuel supply amount, the feedback correction coefficient, and the total learning correction coefficient respectively set as described above, and the fuel supply means sets the set amount. Fuel is supplied to the engine.

<Example> Hereinafter, one example of the present invention will be described with reference to the drawings.

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

In the figure, air is supplied to an internal combustion engine 1 through an area cleaner 2, an intake duct 3, a throttle chamber 4 and an intake manifold 5.

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 interlocking 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, which is driven by an injection pulse signal from a control unit 10 incorporating a microcomputer, which will be described later. The fuel pumped from the fuel pump is injected and supplied into the intake manifold 5.

Further, a water temperature sensor 11 for detecting the cooling water temperature T _W in the cooling jacket of the engine is provided, and the air-fuel ratio is detected from the target air-fuel ratio (theoretical air-fuel ratio) by detecting the oxygen concentration in the exhaust gas in the exhaust passage 12. An oxygen sensor 13 is provided as an air-fuel ratio detecting means for detecting ON or OFF whether it is large or small.

Further, a bypass passage 15 is provided, which bypasses the throttle valve 7 and has a fast idle control valve 14 interposed therebetween. The fast idle control valve 14 is opened when an external load such as an air conditioner or a predetermined amount is applied. By increasing the bypass air flow rate, the output can be increased in proportion to the size of the external load.

The control unit 10 includes a crank angle sensor 16
The engine speed N is detected by counting the crank angle unit signal output in synchronism with the engine speed from the engine for a certain period of time or measuring the cycle of the crank angle reference signal.

The control unit 10 includes the crank angle sensor 16
In addition, signals from the various sensors (these constitute the engine operating state detection means) are input, and ON / OFF signals of the air conditioner switch 17 are input, and the fuel supply amount T is detected based on these detection signals. By setting _I , the fuel injection valve 8 is driven and the opening / closing of the fast idle control valve 14 is controlled. Here, the learning control according to the present invention is performed when setting the fuel supply amount T _I.

The learning control routine will be described with reference to the flowchart of FIG. The learning is performed after the operating state enters a certain area divided by the parameters of the engine speed N for storing the first learning correction coefficient and the basic fuel supply amount T _P set as will be described later. It is performed every time the signal from the oxygen sensor 13 is inverted while staying in the area.

In step (denoted as S in the figure) 1, the oxygen sensor 13
It is determined whether the detection signal of 1 has been inverted a predetermined number of times.

When the number of reversals is less than the predetermined value, the routine proceeds to step 2, and at the time of reversal, the reference value α of the feedback correction coefficient α of the air-fuel ratio set by the fuel supply amount setting routine described later.
The deviation Δα from ₀ is temporarily stored as Δα ₁ .

On the other hand, when it is determined in step 1 that the number of inversions has reached the predetermined value, the process proceeds to step 3, and the deviation Δ of the feedback correction coefficient α of the air-fuel ratio at the time of inversion from the reference value α _0.
Let α be Δα ₂ and average value with the deviation amount Δα ₁ ▲
▼ is calculated by the following equation.

▲ ▼ = (Δα ₁ + Δα ₂ ) / 2 Next, in step 4, the air conditioner switch 17 is turned on and off.
FF judgment is performed. That is, the air conditioner switch 17 and the function of step 4 constitute an external load detecting means for detecting the presence / absence of an external load equal to or more than a predetermined value.

When it is determined to be OFF, the process proceeds to step 5,
Find the first learning correction coefficient K _L1 of the operating conditions in the microcomputer RAM area, said first learning correction coefficient K _L1
Then, the average value of the deviation amount calculated in the above step 3
A new first learning correction coefficient K _L1 is calculated by adding a value obtained by multiplying by a predetermined ratio 1 / M. That is, the RAM that stores the first learning correction coefficient K _L1 as a map constitutes a first learning correction coefficient storage means.

Then, the process proceeds to step 6, wherein the new first learning correction coefficient K _L1, rewritten to correct data in the first learning correction coefficient K _L1 of the same area. That is, the functions of steps 5 and 6 correspond to the first learning correction coefficient correction means.

Further, the process proceeds to step 7, and every time the first learning correction coefficient K _L1 is modified as described above, the value of the counter L that indicates the progress of learning of the first learning correction coefficient K _L1 is incremented. . That is, the counter L corresponds to learning progress detecting means.

On the other hand, 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 L ₀ .

Then, when it is determined that the value is less than the predetermined value, this routine is ended, but when it is determined that the value is the predetermined value or more, the process proceeds to step 9, and the second learning correction coefficient K stored in the RAM.
_L2 is searched, and the same as the second learning correction coefficient K _L1 learning.
Average value of deviation amount ▲ ▼ in learning correction coefficient K _L2 is a predetermined ratio 1
A new second learning correction coefficient K _L2 is calculated by adding the values multiplied by / M ′.

In step 10, the new second learning correction coefficient K _L2 and the current detected value Q of the intake air flow rate detected by the air flow meter 6 are stored as Q ₀ . That is, the RAM corresponds to the second learning correction coefficient storage means, and the steps 9 and 10 correspond to the second learning correction coefficient correction means, and the RAM and step 10 form the intake air flow rate storage means.

Next, the fuel supply amount setting routine will be described with reference to the flowchart of FIG.

In step 11, the basic fuel supply amount T _P 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 the basic fuel supply amount setting means.

In step 12, various correction coefficients COEF are set from the water temperature T _W, etc., if necessary.

In step 13, the first learning correction coefficient K _L1 of the latest corresponding area stored in the RAM is retrieved from the engine speed N representing the engine operating state and the basic fuel supply amount T _P.

In step 14, the voltage correction component T _S is set based on the voltage value of the battery.

In step 15, it is determined whether or not the λ control condition is satisfied.

Here, in the case where the control condition is not 15 (for example, in the high rotation and high load regions), the feedback correction coefficient α is clamped to the previous value (or reference value), and the process proceeds from step 15 to step 20 described later.

For λ control conditions, step 16 to step 18
Output voltage of oxygen sensor 13 and target air-fuel ratio (theoretical air-fuel ratio)
A rich / lean air-fuel ratio is determined by comparing with a corresponding slice level voltage, and a feedback correction coefficient α is set by integral control or proportional-plus-integral control. That is, the steps 16 to 18 correspond to the feedback correction coefficient setting means.

Specifically, in the case of integral control, when it is determined by comparison in step 16 that the air-fuel ratio = rich, the feedback correction coefficient α is decreased by a predetermined integral amount I from the previous value in step 17, and conversely When it is determined that the fuel ratio = lean, in step 18, the feedback correction coefficient α is increased by a predetermined integral amount I from the previous value.

Next, at step 19, the latest first learning correction coefficient K _L1 and second learning correction coefficient K _L2 stored in the RAM and the intake air flow rate are stored.
From Q ₀ , the total learning correction coefficient K _L is calculated by the following equation. That is, the function of step 19 corresponds to the total learning correction coefficient setting means.

K _L = K _L1 + K _L2 · Q ₀ / Q Then, in step 20, the fuel injection amount T _I is finally calculated. That is, the function of the step 20 corresponds to the fuel supply amount setting means.

T _I = T _P · COEF · K _L · α + T _{S When} the fuel injection amount T _I is set in this way, the drive pulse signal with the pulse width of T _I is synchronized with the engine rotation at a predetermined timing. The fuel is output and a set amount of fuel is injected and supplied from the fuel injection valve 8.

In this way, after the learning of the first learning correction coefficient K _L1 for correcting the deviation of the air-fuel ratio from the base air-fuel ratio due to the variation of the air flow meter 6 and the fuel injection valve 8 for each area, to initiate the learning of the second learning correction coefficient K _L2, the second learning correction coefficient K _L2, since it is possible to learn the deviation of the air-fuel ratio according to only increase of the bypass air flow rate, the first learning correction coefficient K _L1 It is possible to suppress the occurrence of a step in the air-fuel ratio in an area where learning does not proceed sufficiently, thereby improving driving performance, fuel efficiency, and exhaust characteristics.

In the present embodiment, the learning progress of the first learning correction coefficient K _L1 is detected as the total value in all operating regions, but there is a difference in the progress of learning depending on the area, and therefore the progress of learning for each area. If the method of detecting the degree and starting the learning of the second learning correction coefficient K _L2 is performed, more accurate control can be performed.

Further, a method may be used in which the learning rate of the second learning correction coefficient K _L2 with respect to all learning is suppressed to a predetermined value or less.

In this embodiment, the method of controlling the fuel supply amount by directly detecting the intake air flow rate is shown. However, in addition to this, the fuel supply amount is controlled based on the throttle valve opening, intake pressure and engine speed. In the controlled system, 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 described above, according to the present invention, the first by area due to variations in parts such as the air flow meter and the fuel injection valve.
Since the second learning corresponding to the increase in the external load is made to proceed after the learning has been performed, the second learning can sufficiently perform the good learning corresponding to only the influence of the increase in the external load. Thus, the step of the air-fuel ratio can be suppressed regardless of the presence / absence of the external load, and the driving performance, fuel efficiency, and exhaust characteristics can be improved.

[Brief description of drawings]

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 flow chart showing a learning control routine of the same embodiment, and FIG. It is a flowchart which shows a supply amount setting routine. 1 ... Internal combustion engine, 6 ... Air flow meter 7 ... Throttle valve, 8 ... Fuel injection valve, 10 ... Control unit, 13 ... Oxygen sensor, 14 ... First idle control valve, 15 ... Bypass passage 16 ...... Crank angle sensor

Claims (1)

[Claims] 1. When an external load exceeding a predetermined level is applied,
In an internal combustion engine in which the air passage that bypasses the intake throttle valve of the engine is opened to increase the intake air flow rate, the engine operating state detection means for detecting the engine operating state and the air-fuel ratio of the engine intake mixture are detected. Fuel ratio detection means, basic fuel supply amount setting means for setting a basic fuel supply amount based on the operating state detected by the engine operating state detection means, air-fuel ratio and target air-fuel ratio detected by the air-fuel ratio detection means And a feedback correction coefficient setting means for setting the feedback correction coefficient for correcting the basic fuel supply amount by increasing or decreasing a predetermined amount so that the actual air-fuel ratio approaches the target air-fuel ratio, and the engine operating state Rewritable first learning correction coefficient storage means for storing a first learning correction coefficient for correcting the basic fuel supply amount for each area; And the external load detecting means for detecting the presence of, the when the external load is not applied, on the basis of the deviation amount from the reference value of the feedback correction coefficient, the first
A first learning correction coefficient correction unit that corrects and rewrites the first learning correction coefficient stored in the learning correction coefficient storage unit in the area of the engine operating state; and a first learning correction coefficient by the first learning correction coefficient correction unit. Learning progress detection means for detecting the progress of correction learning, and rewritable second learning storing a second learning correction coefficient for correcting the basic fuel supply amount when the external load is applied. Correction coefficient storage means, the second learning 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. Second learning correction coefficient correction means for correcting and rewriting the second learning correction coefficient stored in the means based on a deviation amount of the feedback correction coefficient from a reference value; and the second learning correction coefficient. An intake air flow rate detected value storage means for storing a detected value of the intake air flow rate at the time of correction by the positive coefficient correction means, and a latest second 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 the latest first stored in the first learning correction coefficient storage means. A total learning correction coefficient setting means for setting the added value to the learning complementation coefficient as a total learning correction coefficient, a basic fuel supply amount set by the basic basic fuel supply amount setting means, and a feedback correction coefficient setting means. A fuel supply amount setting means for setting a fuel supply amount based on a feedback correction coefficient and a total learning correction coefficient set by the total learning correction coefficient setting means; and an amount of fuel set by the fuel supply amount setting means to the engine. An air-fuel ratio learning control device for an internal combustion engine, comprising: a fuel supply unit that supplies the fuel.