JPS61210241A - Fuel feed control device for engine - Google Patents

Abstract

PURPOSE:To prevent the occurrence of knocking and worsening of fuel consumption through proper correction of unevenness in characteristics of various parts, by a method wherein a fuel injection amount is corrected based on the value of a learning correction factor which learns a feedback correction factor even in an opening control region. CONSTITUTION:A device is provided with an oxygen sensor (a), detecting oxygen concentration in exhaust gas, and an engine operating condition detecting means (b). Further, the device comprises a means (c) which computes a factor, by means of which an air-fuel ratio is corrected to a given air-fuel ratio, based on an output from the oxygen sensor (a) and learns the factor as a factor, responding to a current operating condition, and stores it, and a means (d) which reads out the learning memory value of an air-fuel ratio correction factor from the means (c) to compute an open correction factor. Moreover, it includes a means (e) which alternatively selects the means (c) and (d) according to an operating condition, and controls a fuel feed amount based on the selected correction factor so that an air-fuel ratio is adjusted to a desired value, and a means (f) which feeds fuel to an engine based on an output from the means (e).

Description

Detailed Description of the Invention (Industrial Application Field) The present invention detects the air-fuel ratio based on the exhaust gas components of an engine such as an automobile, and adjusts the amount of fuel supplied so that the air-fuel ratio of the intake air-fuel mixture becomes the target air-fuel ratio. The present invention relates to a device for controlling.

(Prior Art) Recently, there has been a trend that higher fuel economy and drivability are required of engines, and from this point of view, microcomputers and the like are being applied to more precisely control the amount of fuel supplied.

Conventional fuel supply control devices for this type of engine include:
For example, there is one described in Japanese Unexamined Patent Publication No. 58-25540. In this device, the air-fuel ratio is feedback-controlled to the stoichiometric air-fuel ratio based on the output of the oxygen sensor, and the feedback control amount is stored as a learned value for each operating region divided by engine speed and load. The next time the same operating range is reached, the learned value is appropriately corrected and used together with the feedbank control amount, resulting in better responsiveness than control based only on the output of the oxygen sensor, which has a time delay. This improves control accuracy, especially during transient operation.

The hardware configuration of this device is the same as that of the embodiment described later, so it will be omitted, and a program for realizing the above-mentioned control is shown in FIG. In FIG. 4, P1 to PL2 indicate each step of the program, and this program is executed once every predetermined time.

First, read the intake air amount Qa and rotation speed N with P□, and
2, the basic injection amount Tp is calculated according to the following equation (2).

Tp-K ・ (Qa/N) -------■ However, K: Constant This basic injection amount 'rp indicates the injection amount corresponding to the intake air amount Qa per engine revolution, and depends on the engine load. Compatible.

Next, in P3, it is determined whether or not the engine is in the feedback control region using the rotational speed N and the engine load Tp as parameters. When the flow is in the feedback control region, the flow shifts to the feedback flow FBF, and when it is not within the feedback control region, the flow shifts to the open flow OF.

In the feedback flow FBF, at P4, the learning correction coefficient β corresponding to the current operating region is looked up from a table map with N and Tp as parameters, as shown in FIG. β is the value of the feedback correction coefficient α that is learned and stored as a value corresponding to the current operating range, and can be taken as a value that can be predicted in advance for the oxygen sensor output in the operating range. Next, P.

In step P6, a feedback correction coefficient α for correcting the air-fuel ratio to the target air-fuel ratio is calculated based on the output of the oxygen sensor, and in step P6, a corrected injection amount Ti is calculated according to the following equation.

T t = (K ・ (Qa/N))X (1+
α)×(1+β> −−−−−−■ Then, in P7, the learning correction coefficient β is corrected according to the following formula (■) and stored in the corresponding area as the current updated value β'.

β' = (1-x)xβ+x×α −−−−−−■ However, The value will be corrected and stored as the optimum value that has absorbed the change over time of the device. Therefore, the corrected injection amount Ti calculated by formula , which has been corrected to accurately match the target air-fuel ratio.

After passing through the feedback flow FBF, P calculates the final injection amount Te according to the following formula (■), and P and the lever T
An injection signal Si having a valve opening pulse width corresponding to e is output.

Ta-TiX(1+δ)−・−■ ΦIn the formula, δ is the output correction coefficient that corrects the output air-fuel ratio,
Optimum values are stored in advance in the table map shown in FIG. Then, if it is not in the output operating range, δ-0 is set, and if it is in the output operating range, a value corresponding to the degree (δ>O) is set.

On the other hand, when transitioning from step P3 to open flow ○F according to the No command, PK is set to β-0, Pu is set to α-O, and in P7, the corrected injection amount Ti at this time is set as Ti=Tp. Proceed to P8. That is, in this case, the calculation result of Ti is inevitably TiwTp from the calculation result of the above-mentioned formula (2) from the conditions of α-0 and β-0. Then,
In P8, the final injection amount Te is calculated according to the above formula 0.

During open control, it is often in the output operation range, and 0
By calculating the formula, the air-fuel ratio is controlled to the rich side, improving drivability.

(Problem to be Solved by the Invention) However, in such a conventional engine fuel supply control device, the corrected injection amount Ti is corrected by the learning correction coefficient β only in the feedback control region. Therefore, even if the characteristics of parts such as the air flow meter or injector vary due to changes in the equipment over time, Ti is appropriately corrected by β in the feedback control region according to these variations, and the air-fuel ratio is controlled to the target air-fuel ratio. can do.

On the other hand, in the open control region, if the characteristics of the parts described above are not corrected by β and the characteristics of the parts vary, the air-fuel ratio deviates from the target value and drivability deteriorates. For example, when the air-fuel ratio is controlled to the lean side, knocking is induced, and when the air-fuel ratio is controlled to the lean side, fuel efficiency deteriorates.

(Purpose of the Invention) Therefore, the present invention corrects the fuel injection amount based on the value of the learning correction coefficient obtained by learning the feedback correction coefficient even in the open control region, so that regardless of the control mode, the fuel injection amount is The purpose of this system is to appropriately compensate for variations in the characteristics of various parts, suppress the occurrence of non-king and deterioration of fuel efficiency, and improve engine drivability.

(Structure of the Invention) The engine fuel supply control device according to the present invention, as shown in FIG. The detection means calculates an air-fuel ratio correction coefficient for correcting the air-fuel ratio to a predetermined air-fuel ratio based on the output of the oxygen sensor a, and learns and stores this air-fuel ratio correction coefficient as corresponding to the operating state at that time. a first coefficient calculation means C for calculating the air-fuel ratio, and a second coefficient calculation means d for calculating an open correction coefficient for correcting the air-fuel ratio to the target air-fuel ratio by reading out the learning memory value of the air-fuel ratio correction coefficient from the first coefficient calculation means C; The first coefficient calculating means C or the second coefficient calculating means d is selectively selected depending on the operating state, and the fuel supply amount is controlled based on the selected correction coefficient so that the air-fuel ratio becomes the target air-fuel ratio. It is equipped with a supply amount control means e and a fuel supply means f that supplies fuel to the engine based on the output of the supply amount control means e, and regardless of the control mode, variations in characteristics of various parts of the device can be prevented. This is an appropriate correction.

(Example) Hereinafter, the present invention will be explained based on the drawings.

FIG. 2.3 is a diagram showing an embodiment of the present invention.

First, the configuration will be explained. In FIG. 2, reference numeral 1 denotes an engine, in which intake air is supplied from an air cleaner 2 to each cylinder through an intake pipe 3, and fuel is injected by an injector (fuel supply means) 4 based on an injection signal Si. A spark plug 5 is attached to each cylinder, and a high-pressure pulse is supplied to the spark plug 5 at a predetermined ignition timing. The air-fuel mixture in the cylinder is ignited and exploded by the high-pressure pulse discharge, and is discharged through the exhaust pipe 6 as exhaust gas.

The intake air flow rate Qa is detected by an air flow meter 7 and controlled by a throttle valve 8 in the intake pipe 3. The rotation speed N of the engine 1 is detected by a crank angle sensor 9, and the oxygen concentration in exhaust gas is detected by an oxygen sensor 10. The oxygen sensor 10 has a characteristic that the output voltage Vs suddenly changes after reaching the stoichiometric air-fuel ratio.

The air flow meter 7 and the crank angle sensor 9 constitute an operating state detecting means 11, and signals from the operating state detecting means 11 and the oxygen sensor 1o are input to the control unit 12. The control unit 12 performs fuel supply control based on the sensor information.

The control unit 12 has functions as a first coefficient calculation means, a second coefficient calculation means, and a supply amount control means, and includes a CPU 21, a ROM 22, a RAM 23, and an I1
Consists of 0 votes U. CPU21 is ROM22
I10 boat 2 according to the program written in
You can import the external data you need from 4, and also use RA.
It does not exchange data with the M23, but calculates the processing values necessary for fuel supply control, and outputs the processed data to the 110 port as necessary. (2) Signals from the respective sensors 1O111 are input to the 10 port A, and an injection signal St is output from the I10 boat 24. The ROM 22 stores calculation programs for the CPU 21, and the RAM 23 stores data used in calculations in the form of a map or the like.

Next, the effect will be explained.

FIG. 3 is a flowchart showing a fuel supply control program written in the ROM 22.

In explaining this program, steps that perform the same processing as in Figure 4 shown as a conventional example are given the same numbers and their explanations are omitted, and steps that perform different processing are given numbers in the 20s and the processing details. Explain.

In FIG. 3, in the last step P21 in the feedback flow FBF, the open correction coefficient γ is calculated according to the following equation (2), and the process proceeds to P8.

γ=Σβi+n −−−−−−１■wl The open correction coefficient γ is the value obtained by averaging the learning correction coefficient β in each operation area divided into n over all operation areas. It can be viewed as data that corrects variations in the characteristics of various parts. The value of γ is always corrected to the latest data each time the feedback flow FBF is executed, and is stored at a predetermined address.

On the other hand, in open flow OF, first look up the open correction coefficient γ with Pax, then P23 through Pl+.
Then, the corrected injection amount Ti is calculated according to the following equation (2), and the process proceeds to P8.

Ti= (K・ (Qa/N))X (1+y)−・～
(2) Even in the open control region, the final injection amount Te is corrected to a value that corrects variations in the characteristics of the air flow meter 7 and the injector 4 by calculating Equation 0.

That is, even if there are variations in the characteristics of various parts, the extent of the variations can be grasped by learning and storing information from the oxygen sensor 10 according to the operating state. And the degree of this dispersion is always equal to the initial data γ
Since the injection amount is immediately corrected based on this γ during open control, the air-fuel ratio can be accurately controlled to the target air-fuel ratio, unlike in the past. Therefore, even during open control, the occurrence of non-king and deterioration of fuel efficiency can be suppressed, and the drivability of the engine 1 can be improved.

(Effects) According to the present invention, even during open control, variations in the injection amount caused by changes in the characteristics of various parts due to changes in the device over time etc. are appropriately corrected, and the fuel supply amount is adjusted to the target air-fuel ratio. This makes it possible to control the occurrence of knocking and deterioration of fuel efficiency, thereby improving engine drivability.

[Brief explanation of drawings]

Fig. 1 is a basic conceptual diagram of the present invention, Figs. 2 and 3 are diagrams showing an embodiment of the fuel supply control device according to the present invention, Fig. 2 is an overall configuration diagram thereof, and Fig. 3 is a diagram showing the fuel supply control device according to the present invention. Flowchart showing the fuel supply control program, FIG. 4.5 is a diagram showing a conventional engine fuel supply control device, FIG. 4 is a flowchart showing the fuel supply control program, and FIG. 5 is the learning correction coefficient. and FIG. 7 is a diagram showing an operating region to which an output correction coefficient is assigned using rotation speed and load as parameters. 1-----1 engine, 4-----injector (fuel supply means), 10.-
-1--Oxygen sensor, 11---Operation state detection means, 12-... Control unit (first coefficient calculation means, second coefficient calculation means, supply amount control means).

Claims (1)

[Scope of Claims] a) an oxygen sensor that detects the oxygen concentration in exhaust gas, b) an operating state detection means that detects the operating state of the engine, and c) an air-fuel ratio that is set to a predetermined air-fuel ratio based on the output of the oxygen sensor. d) a first coefficient calculation means for calculating an air-fuel ratio correction coefficient to be corrected to the current value, and learning and storing this air-fuel ratio correction coefficient as one corresponding to the operating state at that time; a second coefficient calculating means for calculating an open correction coefficient for correcting the air-fuel ratio to the target air-fuel ratio by reading out the learning memory value of the coefficient; and e) selecting the first coefficient calculating means or the second coefficient calculating means according to the operating condition. a supply amount control means for controlling the fuel supply amount so that the air-fuel ratio becomes a target air-fuel ratio based on the selected correction coefficient; A fuel supply control device for an engine, comprising: a fuel supply means for supplying; and a fuel supply control device for an engine.