JP3017298B2 - Engine fuel control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control device for an engine, and more particularly to a fuel control device for an engine for predicting a fuel injection amount.

[0002]

2. Description of the Related Art Conventionally, it has been desired to accurately supply a fuel supply amount commensurate with the amount of air actually absorbed into a combustion chamber from the viewpoints of driving performance and exhaust gas purification performance.
For example, Japanese Patent Application Laid-Open No. Sho 60-116840 discloses that the fuel supply accuracy is improved by measuring the air amount a plurality of times during the intake stroke and supplying a plurality of times of the fuel according to the measured air amount. It has been disclosed.

However, in the above prior art,
Since the air amount changes from the time of the last fuel injection to the end of the intake stroke, there is a problem that the fuel supply amount is shifted by the air amount change during that time. Therefore, it is conceivable to predict the intake air amount at the end of the intake stroke at a timing before the end of the intake stroke, and to perform the fuel injection control based on the predicted amount.

[0004]

In the above-mentioned conventional fuel control system, the prediction of the air amount is made from the rate of change of the air amount and the time before the end of the intake stroke. If the intake air amount suddenly decreases or the operating state changes, the predicted value will increase with respect to the true intake air amount, that is, the predicted intake air amount will overshoot and the fuel injection amount will be excessive .

Therefore, even if guarding is performed so that the predicted intake air amount does not exceed the maximum intake air amount when the throttle is fully opened,
When the intake air amount is less than the maximum intake air amount, overshooting occurs below the guard value, so that the effect is insufficient. The present invention has been made in view of such a point, and an object thereof is to change the degree of prediction of the amount of intake air according to the operating state because the degree of change of the amount of intake air changes with the operating state. Accordingly, it is an object of the present invention to provide an engine fuel control apparatus that enables overshooting of an intake air amount prediction value and improves controllability of an air-fuel ratio.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has the following arrangement as means for solving the above-mentioned problems. That is, first detecting means for detecting a change in the air amount within a predetermined period immediately before the end of the intake stroke of each cylinder of the engine, and the air amount at the end of the intake stroke based on the detection result by the first detecting means. And a first predicting means for predicting the amount of fuel. The fuel controlling apparatus for an engine supplies an amount of fuel according to the air amount predicted by the first predicting means. Control means for controlling the degree of prediction of the air amount to be changed according to the operating state of the engine.

Preferably, the operating state detected and predicted by the second detecting means and the second predicting means is a throttle opening.

Preferably, the guard means guards the air amount predicted by the first predicting means with an intake air amount determined by a throttle opening and an engine speed. Further, the following configuration is provided as means for solving the above-mentioned problem. That is, first detecting means for detecting an actual intake air amount in each cylinder of the engine;
A fuel supply means for injecting fuel in accordance with the intake air amount detected by the detection means, and detecting a change in the air amount within a predetermined period from after the fuel injection by the fuel supply means to the end of the intake stroke. A second detecting unit; and an air amount predicting unit that predicts an air amount at the end of the intake stroke based on a detection result of the second detecting unit. The amount of fuel corresponding to the amount of air predicted by the means is additionally injected at the time of prediction by the intake amount predicting means.

[0009]

With the above arrangement, it is possible to predict an appropriate amount of air regardless of a change in the amount of intake air due to a change in the operating state.

[0010]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. <First Embodiment> FIG. 1 is a diagram showing an overall configuration of an engine fuel control apparatus (hereinafter referred to as an apparatus) according to an embodiment of the present invention. In FIG. 1, a piston 2 slides in a combustion chamber 3 of an engine body 1, and an intake port 4 and an exhaust port 6 are supported in the combustion chamber 3. An intake valve 7 is provided between the intake port 4 and the combustion chamber 3 and an exhaust port 6
An exhaust valve 8 is disposed between the combustion chamber 3 and the combustion chamber 3.

A throttle valve 9 for controlling the amount of intake air is provided upstream of the intake port 4, and a surge tank 10 as an intake expansion chamber is provided downstream thereof. Further downstream, there is an injector 11 for injecting and supplying fuel.
Is provided. The intake air amount to the intake port 4 is detected by an air flow sensor 20a in the air flow meter 20, and the temperature of the intake air is detected by an intake air temperature sensor 21. The throttle opening sensor 22 incorporates an idle switch (not shown) and detects the opening of the throttle valve 9. The distributor 15 is provided with a rotation speed sensor 25 for detecting the engine rotation speed and a crank angle sensor 28 for detecting the crank angle.
Is provided with an O ₂ sensor 26.

Further, the torque converter 5 is provided with a turbine speed sensor 12 for detecting a turbine speed. Engine control unit (ECU) 30
Receives an output from each of the above-described sensors, sends an ignition time control signal to the distributor 15, and sends a control signal to the injector 11 to adjust the fuel injection amount. In addition, various maps described later are stored in a built-in memory (not shown).

Next, the control of fuel injection in the apparatus of the present embodiment will be described in detail. FIG. 2 is a flowchart showing a fuel injection control procedure in the device of the present embodiment. FIG. 3 is a diagram showing the relationship between the prediction of the intake air amount and the prediction of the throttle opening. 2, the engine control unit (ECU) 30 determines in step S1 the Ce- in FIG. 3 based on the detection result of the air flow sensor 20a.
1. Intake air amounts Q _i-1 and Q _i at points A and B shown on the characteristics
Read. Then, in step S2, the rate of change ΔQ = (Q _i −Q _i−1 ) from the intake air amount obtained in step S1.
/ Seek t _1. In the following step S3, the intake air amount Q at the time of In-close (point C) is calculated based on the change rate ΔQ. This prediction amount Q is obtained by the following equation, where the prediction point is point B.

Q = Q _i + {(Q _i −Q _i−1 ) / t ₁ } × t ₂ (1) In step S4, the predicted amount of intake air calculated and predicted in step S3 and a predetermined set value Is performed, and if the set value exceeds the predicted amount, the process proceeds to step S12.
The normal injection amount is calculated based on the actual intake air amount at that time. However, if the predicted amount is larger than the set value, the process proceeds to step S5, where the throttle opening TVO at that time is read based on the signal from the throttle opening sensor 22.
That is read point D on TVO characteristics of Figure 3, the Surotsutoru opening TVO _i-1, TVO _i in E. Then, in step S6, the rate of change ΔTVO of the throttle opening TVO is determined in the same manner as the above-described intake air amount.

That is, the rate of change Δ of the throttle opening TVO
TVO is represented by ΔTVO = (ΔTVO _i −ΔTVO _i−1 ) /
because it is t _3, in step S7, In-close
The predicted throttle opening TVO at the time (point F) is calculated by TVO = TVO _i + {(TVO _i −TVO _i−1 ) / t ₃ } × t ₄ (2), with the predicted point being point E.

In step S8, the engine speed is read based on the signal from the speed sensor 25, and a guard value of the predicted intake air amount is set from the map shown in FIG. The guard value tends to increase as the predicted throttle opening TVO increases, and to increase as the engine speed decreases. This is the throttle opening TVO
This is because the relationship between the engine speed and the filling amount changes depending on the engine speed, and even if the throttle opening is the same, the lower the engine speed, the higher the filling amount.

In the next step S9, the guard value obtained in step S8 is compared with the predicted amount of intake air predicted and calculated in step S3. If the predicted amount is smaller than the guard value, the process proceeds to step S11, where the prediction is performed. The injection amount is calculated based on the value. However, if the guard value is smaller than the predicted value, the injection amount based on the guard value is calculated in step S10. Then, in step S13, step S1
The fuel is injected according to the injection amount calculated at 0, S11, or S12.

FIG. 5 shows a state in which the intake air amount is guarded by the predicted throttle opening TVO.
The intake air amount is guarded at a point P corresponding to the time of ose. As described above, according to the present embodiment, the attained throttle opening during In-close is predicted in synchronization with the prediction of the intake air amount, and the intake air amount is calculated based on the predicted value of the throttle opening. Is guarded below the maximum intake air amount, an area where the injection amount is insufficient is eliminated, and the controllability of the air-fuel ratio control can be improved. <Second Embodiment> Next, a second embodiment according to the present invention will be described. Note that the overall configuration of the engine fuel control device according to the present embodiment is the same as that of the first embodiment, and a detailed description thereof will be omitted here.

In the first embodiment, the intake air amount is predicted and calculated by a linear line. In this embodiment, this prediction is performed by a quadratic curve, and fuel is injected into each cylinder and one cycle of the engine. The case of performing twice will be described. FIG. 6 is a flowchart illustrating the fuel injection control according to the present embodiment. In the figure, in step S21, the injection amount is calculated based on the actual intake air amount read at that time, and normal injection is performed without predicting the air amount (here, the injection to cylinder # 1 is taken as an example). To take). In step S22, points B, C, and D located at regular intervals from the normal injection end time (corresponding to point A) on the Ce-2 characteristic shown in FIG.
The intake air amount at is read, and in the following step S23,
The air amount is predicted by applying the value obtained in step S22 to the defining equation.

[0020] Specifically, the point B, C, reads the intake air amount at the sampling interval t _s in D, air volume Ce
_i , Ce _i-1 and Ce _i-2 are obtained. Then, a variable H that changes according to the engine speed is obtained by dividing the time β from the start of additional injection to In-close, which will be described later, by the sampling interval t _s . Predicted air amount C after β from the start of additional injection
ee can be obtained as a quadratic expression suitable for actual measurement by the following definition expression.

[0021] _{Cee = {(Ce i -Ce i} -1) - (Ce i-1 -Ce i-2)} × H 2/2 + (Ce i -Ce i-1) × H ... (3) where in H = β / t _s step S24, the equation predicted air amount Cee obtained in (3) it is determined whether more than a predetermined value, the judgment result is Y
If it is ES, the additional injection amount is calculated in step S25.
Then, in step S26, FIG.
Additional injection is performed at the point indicated by point E in FIG. This additional injection is based on the result of sampling the intake air amount immediately after the normal injection and calculating the predicted air amount Cee based on those values according to equation (3) as described above. However, it has the meaning of dividing and injecting so as to compensate for the subsequent change in the amount of intake air. Therefore, when it is determined in step S24 of FIG. 6 that the predicted air amount Cee is equal to or smaller than the predetermined value, the additional injection is not performed.

As described above, according to this embodiment,
Normal injection is performed based on the actual intake air amount, and immediately after that, by predicting the air amount at the time of In-close from the secondary definition equation, the deviation between the actual value and the predicted air amount can be reduced, Further, since the additional injection is performed based on the predicted air amount, there is an effect that the fuel corresponding to the air actually entering the combustion chamber can be injected.

[0023]

[0024]

[0025]

[0026]

As described above, according to the present invention,
There is an effect that it is possible to predict an appropriate amount of air irrespective of a change in the amount of air due to a change in the operating state of the engine, thereby improving controllability of fuel.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an engine fuel control device according to an embodiment of the present invention;

FIG. 2 is a flowchart showing a fuel injection control procedure according to the first embodiment;

FIG. 3 is a diagram showing a relationship between a prediction of an intake air amount and a prediction of a throttle opening according to the first embodiment;

FIG. 4 is a diagram showing a map for setting a guard value of a predicted intake air amount,

FIG. 5 is a diagram showing a state in which the intake air amount is guarded at a predicted throttle opening TVO,

FIG. 6 is a flowchart showing fuel injection control according to a second embodiment;

FIG. 7 is a diagram showing a relationship between prediction of air amount and fuel injection according to a second embodiment;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine main body 2 Piston 3 Combustion chamber 4 Intake port 5 Torque converter 6 Exhaust port 7 Intake valve 8 Exhaust valve 9 Slottle valve 10 Surge tank 11 Injector 12 Turbine speed sensor 15 Distributor 20 Air flow meter 20a Air flow sensor 21 Intake temperature sensor 22 Throttle opening sensor 25 Rotation speed sensor 25 26 O ₂ sensor 28 Crank angle sensor

Claims (4)

(57) [Claims] 1. Before the end of an intake stroke of each cylinder of an engine ,
First detecting means for detecting a change in the air amount within a predetermined period before the fuel injection; and first prediction for predicting the air amount at the end of the intake stroke based on a result detected by the first detecting means. Means for injecting an amount of fuel corresponding to the amount of air predicted by the first predicting means at the time of prediction by the first predicting means.
A fuel control device for an engine that performs an intake stroke of each cylinder of the engine and before a fuel injection.
Operating state of the engine other than the amount of air within the specified period
Detection means for detecting a change in the intake stroke, and the end of the intake stroke based on the detection result of the second detection means.
Second prediction means for predicting a final operating condition of Ryoji, to the air amount is predicted by said first prediction means, said first
Intake air determined by the final operation state predicted by the prediction means 2
A fuel control device for an engine, comprising a guard means for guarding by an amount . 2. The second detecting means and the second predicting means.
The operating state detected and predicted at is the throttle opening
Fuel control system for an engine according to claim 1, characterized in that. 3. The guard device according to claim 1, wherein the guard device guards the air amount predicted by the first predicting device with an intake air amount determined by a throttle opening and an engine speed. Engine fuel control system. 4. A first detecting means for detecting an actual amount of intake air in each cylinder of the engine, and a fuel supply means for injecting fuel in accordance with the amount of intake air detected by the first detecting means. At the end of the intake stroke after fuel injection by the fuel supply means
Second detecting means for detecting a change in the air amount within a predetermined period of time up to, and air amount estimating means for estimating the air amount at the end of the intake stroke based on the detection result of the second detecting means. Wherein the fuel supply means predicts an amount of fuel according to the air amount predicted by the air amount prediction means by the intake air amount prediction means.
An engine fuel control device, characterized in that additional injection is performed at a point .