JPS6045753A - Fuel controller of internal-combustion engine - Google Patents

Abstract

PURPOSE:To constantly perform control of mixture at a demanded air fuel ratio and attain immediate increase of fuel in response to the urgent acceleration by controlling the quantity of fuel to be supplied plus the dynamic characteristics of a fuel control system and supplying additional fuel for acceleration immediately after the state where the demanded quantity of fuel is urgently increased is detected. CONSTITUTION:After reading an air quantity signal S1, namely, Aa(n-1) developed by an air flow meter 4, a revolution signal S2, etc., a computer calculates the value Ac(n) of the quantity of intake air measured in the current control period and makes foreseeing calculation of the value Ac(n+1) of the quantity of the subsequently measured intake air. Using the intake air quantity Ac(n)m the computer calculates the currently demanded quantity Fc(n) of fuel and calculates the quantity Ff(n) of fuel which is to be injected actually in order to send the demanded quantity of fuel into a cylinder. If accelerated injection is carried out, the computer calculates both Fa(a) and Fa(n+1). Fa(a) is the quantity of fuel which is actually sucked into the cylinder when injected at an accelerated speed. If the accelerated fuel has a considerable effect, the computer generates the injection signal S3 of an injection pulse width according to the quantities F'c(n) and F'(n+1) of fuel incremented by the acceleration, whereby increasing the quantity of fuel without any delay.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fuel control device for an internal combustion engine, and in particular to a device for correcting an imbalance between the intake air amount and the fuel supply amount caused by the dynamic characteristics of the air system and the fuel system. related to technology.

[Prior art]

As a conventional fuel control device, for example, there is the one shown in FIG.
5165, 55-134718, etc.).

In FIG. 1, 1 is an air cleaner, 2 is an intake pipe, the lower is a throttle valve, 4 is an air flow meter that outputs an air amount signal S1 corresponding to the amount of air passing through the intake pipe 2, and 5 is a fuel injection amount signal, which will be described later. 6 is a cylinder, 7 is a rotation sensor that outputs a rotation signal IS2 synchronized with the rotation of the crankshaft, and 8 is mainly based on the air amount signal S1 and rotation signal S2. It is a calculation device that calculates the fuel injection amount corresponding to the driving state at that time and outputs the fuel injection amount signal S3 according to the result.
It is composed of a micro converter consisting of PU, RAM, ROM, Ilo, etc.

The calculation of the fuel injection amount in the device described in ``2'' is performed as follows.

In other words, the air amount signal S1 measured by the air flow meter 4
When the intake air amount obtained by is Q, the rotation speed of the internal combustion engine obtained from the rotation signal S2 is N, and the coefficient is (), the fuel injection amount (fuel injection pulse width) Tp is as follows (1)
Calculated by the formula.

As shown in equation (1) above, the fuel injection amount is mainly set according to the intake air amount and rotational speed, and the actual fuel injection amount is the one that adds corrections based on temperature, exhaust gas component concentration, etc. .

However, in the conventional device, the air amount signal S1 of the air flow meter is used as it is as a signal indicating the amount of intake air, and control is performed on the assumption that all the fuel injected at short intervals is taken into the cylinder without any time delay.

In other words, in conventional devices, the air amount is the measured value of the air flow meter itself, and the fuel amount is the fuel injected into the intake pipe, but does not control the amount of air or fuel actually taken into the cylinder. There wasn't.

Therefore, accurate control is possible in a steady state, but in a transient state, errors occur due to the dynamic characteristics of the air system and fuel system, which causes the air-fuel ratio to deviate from the target value, resulting in poor fuel efficiency, exhaust purification performance, and operational performance. There was a problem that performance etc. were adversely affected.

In order to solve the above problem, the applicant calculates the actual intake air amount in the cylinder from the dynamic characteristics of the air system that have been measured and stored in advance and the air amount signal S1 of the air flow meter, and calculates the actual intake air amount in the cylinder. By calculating the required fuel amount of the internal combustion engine from the above, and then calculating the actual amount of fuel to be supplied from the dynamic characteristics of the fuel system and the above required fuel amount, it is possible to correct errors caused by the dynamic characteristics of the fuel. We have already applied for a control device (Japanese Patent Application No. 16150/1982).

The above device is an excellent device that can effectively correct errors caused by the dynamic characteristics of the fuel control system. However, when the dynamic characteristics of the fuel system are slower than those of the air system, for example when the injection point is far from the cylinder, such as when fuel is injected into the throttle body, a method that calculates the fuel supply amount from the air flow rate is used. Since the change in fuel lags behind the change in air, it is extremely difficult to completely correct errors that occur during transient conditions.

Therefore, the above device is extremely effective against relatively gradual changes in the throttle valve opening, but it supplies a richer mixture than under normal conditions during sudden acceleration when the throttle valve opening opens rapidly, or during acceleration. When fuel is quickly supplied to the cylinder, for example, when fuel is quickly supplied to the cylinder, there is a problem that the correction function is not available in time, resulting in insufficient control. This system is designed to increase the amount of fuel actually supplied to the cylinders without delay even when the amount of fuel required by the internal combustion engine suddenly increases, such as during sudden acceleration, and to always control the air-fuel ratio to the desired air-fuel ratio. The purpose of the present invention is to provide a fuel control system capable of

[Summary of the invention]

In order to achieve the above object, the present invention calculates the actual intake air amount in the cylinder from the dynamic characteristics of the air system measured and stored in advance and the air amount signal S1 of the air flow meter. The required fuel amount of the internal combustion engine is calculated from the value, and the actual amount of fuel to be supplied is calculated from the dynamic characteristics of the fuel system and the above required fuel amount. provide means for detecting
When the state in item 2 occurs, the configuration is configured to rapidly increase the amount of fuel actually supplied to the 7S/DA by immediately supplying acceleration fuel in addition to the amount of fuel determined by the calculation in item 2. are doing.

In another configuration of the present invention, when the above acceleration fuel is supplied, an amount obtained by subtracting the amount of fuel sucked into the ring by the acceleration fuel from the fuel amount determined by the above calculation is supplied. , so that there is no excess fuel.

FIG. 2 is a block diagram showing the overall configuration of the present invention.

In FIG. 2, 100 is a sensor that outputs an air amount signal related to the amount of intake air, such as an air flow meter. 101 is a memory that stores the dynamic characteristic G21 between the air amount signal and the amount of intake air actually taken into the cylinder; 102 is a memory that stores the dynamic characteristic G21 between the above air amount signal and the amount of intake air actually taken into the cylinder; 102 stores the actual intake air from the above air amount signal and the dynamic characteristics G and I 106 is an engine operating variable other than the intake air amount (engine speed, temperature, etc.)
one or more sensors 104 detecting the fuel supply means 10;
A memory 105 stores the dynamic characteristic Gf between the amount of fuel delivered by the fuel injection valve or the like and the amount of fuel actually sucked into the cylinder; Calculating means 106 that calculates the required fuel amount of the internal combustion engine at that time from the actual intake air amount given from the calculating means 102, and calculates the amount of fuel to be supplied from the required fuel amount and the above dynamic characteristic Of; is a detection means for detecting a state in which the amount of fuel required by the engine increases rapidly, and is, for example, a sensor that outputs a signal according to the rate of change of the throttle valve opening. Reference numeral 107 denotes a fuel signal generating means, which normally sends out a fuel signal according to the calculation result of the calculation means 105, or immediately sends out an acceleration fuel signal when a signal from the detection means 106 is given. It should be noted that better control can be achieved by setting the acceleration fuel signal to a constant value or to a value depending on the signal from the detection means 106, that is, a value depending on the state of increase.

The fuel supply means 108 (fuel injection valve, etc.) supplies an amount of fuel to the engine according to the signal from the fuel signal generation means 107 described above.

Due to the configuration described above, when the amount of fuel required by the engine increases rapidly, for example during sudden acceleration, it is possible to quickly supply accelerating fuel based on information on the amount of intake air before the amount of fuel supplied increases. Even if the dynamic characteristics of the fuel system are slower than those of the air system, it is possible to respond well to a sudden increase in the amount of fuel required, and it is possible to supply a mixture with a desired air-fuel ratio to the cylinder.

Next, when the acceleration fuel is supplied as described above, the fuel supply amount increases by the amount of the acceleration fuel compared to the fuel supply amount determined by the calculation means 105.

Since the calculation means 105 outputs a fuel signal according to the amount of fuel required by the engine regardless of the presence or absence of acceleration fuel, during sudden acceleration, the value of the fuel signal increases as the amount of intake air increases after a certain delay time. .

Therefore, there is a risk that the fuel will be in excess of the previously supplied acceleration fuel, and the air-fuel mixture may become too rich.

In order to solve the above problem, as shown by the broken line in FIG. When acceleration fuel is supplied, the value determined by the calculation means 109 is subtracted from the fuel amount calculated by the calculation means 105, and Of
It may be configured to calculate the amount of fuel to be supplied using .

[Embodiments of the invention]

The present invention will be described in detail below based on examples.

FIG. 6 is a diagram showing an embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same parts.

In FIG. 6, reference numeral 9 indicates a throttle valve that outputs a detection signal S4 when the throttle valve 6 changes from fully closed to open.

The computing device 10 includes, for example, an input/output device 11 and a CPU 1.
2, T(, AM13, ① are also composed of microcombees made of OMj4, etc.).

The arithmetic device 10 inputs signals related to engine operating variables such as an air amount signal S1, a rotation signal S2, a detection signal S4, and a temperature signal (not shown), and receives a predetermined 6! j calculation is performed and a fuel injection amount signal S3 is output.

By controlling the fuel injection valve 5 with the fuel injection amount signal S, the fuel required by the engine is supplied.

Next, the calculations within the calculation device 10 will be explained in detail based on the flowchart of FIG.

First, FIG. 4(A) shows an interrupt routine.

That is, the detection signal of the throttle switch 9 is used as an interrupt signal to interrupt the calculation of the calculation device 10, and (A)
executes the interrupt routine.

In this interrupt routine, accelerating fuel is injected at Pl, and the accelerating injection flag is set to °1' at P2 for later calculations.

Next, FIG. 4 (I3) shows a normal fuel control routine, which is performed in synchronization with the rotation of the engine or at regular intervals.

First, at P3, the output of the air flow meter 4, that is, the air amount signal S1, that is, Aa (n-1) is read.

However, 1]-1 indicates the value in the previous control cycle. That is, it means that the output value of the air flow meter 4 read last time is used here.

Although not shown, the rotation signal 82 and the like are also read.

Next, in P4, the value A of the intake air amount in the current control cycle.
. (n) is calculated. This operation proceeds as follows.

The dynamic characteristics of the air system in the intake system (air flow meter, intake pipe, etc.) of an internal combustion engine can be well described using, for example, a second-order pulse transfer function.

Then, the above Aa (n-1), the value Aa (n-
2), the value A of the intake air amount before the first time and the second time before. (n-
1), Ao(n-2), and the current intake air amount value A from equation (2). (11) becomes the following equation (3).

Ao(n)'= dlAa(n-j)+e1Aa(n
2)-blAo(n-1)-clAo(n-2)・・
・ (B) Therefore, if you experiment in advance with the above coefficients 1]1, C1, dl, (2), you can calculate Ao(n). ) may be approximated as shown in the formula A.(I]), or may be approximated by including the Zo term in the numerator of G a (z ). In this case, A-o Aa(11) to calculate (n)
In other words, the current value will be used.

The values of each of the above-mentioned coefficients are the values that have been actually tested and stored in (0M14 or RAM 13).

Next, at P5, the next intake air amount value Ao(n+
1) is predictively calculated.

For example, this value can be calculated by using an extrapolation formula to calculate Ao('n+1): 2Ao(I]) -Ao(n-1) from the current and previous intake air amount values.
) can be stopped. Note that the reason why the prediction calculation of Ac (1] + 1) is necessary will be described later.

Next, at P6, the intake air amount A obtained at P4.

Using (n), the current required fuel amount F is calculated from equation (4) below.
Compute o(n).

The above required fuel amount F. (1) is the amount of fuel actually required in the ring corresponding to the actual amount of intake air.

Next was P7, an A that I got on P5. (+1+1) is used to determine the next required fuel amount F. (n+1) is calculated from the following equation (5).

If the acceleration injection flag is 0, then in P8, the fuel amount Fr(n) that should actually be injected in order to supply the above-mentioned required fuel amount to the cylinder is calculated.

For example, if the dynamic characteristics of the fuel system are Gf(z), the amount of fuel to be injected this time Ff(n) is as follows (
7) The formula is as follows.

+c2Fo(n-1) -C2F((n-1),:
1...(7) Therefore, if the above coefficients b2, C2, d2, and C2 are determined in advance through experiments, Ff(n) can be determined by calculation.

For each coefficient in ``1'', the values stored in l(, 0M14, etc.) are used.

Note that if Ac (n + i) is predicted and calculated in P5, F is obtained in P7. This is to calculate (n+1),
It's a size F. (n+1) is needed to calculate Fl(n) at P8.

In this example, the dynamic characteristics of the fuel system are described as in equation (6), so the predictive calculation of P5 above is required, but the dynamic characteristics of the air system and fuel system can be expressed using simpler equations For example, in equation (6), the denominator is b2z+C
In the case where only 2z is obtained, (F of the formula (n+
1) is no longer necessary, and therefore the prediction calculation of Ac (n + 1) is also no longer necessary.

Next, in the case of Y and E at P, that is, when acceleration injection is performed, the process goes to Plo, where the amount Fa(n) of the injected acceleration fuel actually sucked into the cylinder and F, (n
+1). This calculation is performed in (6) and (7) above.
) is calculated from the dynamic characteristics Gr(z) of the fuel system.

Next, P11 is F′C(n) = F((n) −F
, (n) and F'C(11+1)-F. (n+1)-F
Calculate a(n+1).

Next, in P12, it is determined whether to end the calculation of Fa (n) in Plo.

This determination is completed when the influence of the accelerating fuel has become sufficiently small, for example, when the value of II'a(n) has become smaller than a predetermined value.

If NO at P12, immediately go to P14 and set P,'(n
), outputs a fuel injection amount signal S6 having an injection pulse width corresponding to F2(n +1 ).

If YES in P12, go to P13 and set the accelerated injection flag to "0", so that from the next calculation, P1o ~
Avoid passing through the route P13 and return to normal control.

In the above embodiment, if steps P to P13 are omitted, the control does not subtract the acceleration fuel.

Even better control can be achieved by changing the amount of acceleration fuel in accordance with the rate of change of the throttle valve opening.

In that case, a throttle processor that outputs a signal corresponding to the throttle valve opening and a means for detecting the rate of change of the signal are provided in place of the flow control valve opening 9, and a means for detecting the rate of change of the signal is provided. All you have to do is change the amount of acceleration fuel.

In this case, Plo is divided by Fa(1]) according to the acceleration fuel injected at that time.

FIG. 5 is a diagram showing changes in intake air amount and fuel amount in an internal combustion engine.

In Fig. 5, (A) is the output of the air flow meter, (
The solid line in B) is the amount of air taken into the cylinder, the dashed line is the amount of fuel taken into the cylinder, (C) is the amount of fuel injection considering dynamic characteristics, and (D) is the intake in the cylinder in case of (C). Air amount (solid line) and fuel amount (dashed line), (J is the acceleration fuel of the present invention, (F) is the fuel amount sucked into the cylinder by injecting the acceleration fuel, (G) is from the required fuel amount The amount of supplied fuel calculated from the result of subtracting (F), (I-
I) shows the intake air amount (solid line) and fuel amount (broken line) in the cylinder due to the injection of (E) + (G), respectively.

Although it is impossible for the output of the airflow meter to actually change in a stepwise manner during the change (A), for the sake of clarity, we will use the time T. Assume that there is a sudden change as shown in (A). - If the fuel injection amount is set using the output of the air flow meter as in the conventional device, due to the dynamic characteristics of the air system and fuel system as described above, the intake air amount and fuel amount in the cylinder will be is shown in (B)'', and To-T
Between 1 and 1, there is too little fuel and the mixture becomes lean;
-72, there is too much fuel and the mixture becomes too rich.

Therefore, considering the dynamic characteristics of the intake system as described above, (C)
When fuel is injected according to the characteristic of equation (7) as shown in (D), the imbalance between the amount of intake air and the amount of fuel is considerably improved, as shown in (D).

However, as can be seen from D), the fuel amount lags behind the intake air amount to some extent, and if the fuel control is performed too early in an attempt to improve this, there is a problem that the stability in steady state will worsen. arise.

In the present invention, as shown in (E), accelerating fuel is injected immediately at time T3 (T is earlier than T) when the throttle valve opening changes, and the fuel is sucked into the cylinder by the injection. A value (G) calculated based on the amount (F) subtracted from the required fuel amount is injected.

Therefore, in the present invention, as shown in (I), there is no fuel delay, the intake air amount and fuel amount can be kept in balance even during a transient state, and the air-fuel ratio can be maintained at a desired value. Note that the shaded part (g) indicates the acceleration fuel.

Furthermore, if it is desired to make the air-fuel mixture a little richer during acceleration, the acceleration fuel amount need not be subtracted as described above.

Next, FIG. 6 is a time chart when the present invention is applied to a six-cylinder engine.

FIG. 6 shows a case in which fuel injection is performed once per rotation in synchronization with a 1200 signal output every time the crank angle rotates by 120 degrees in a fuel injection system for a six-cylinder engine. Note that the fuel injection amount is proportional to the pulse width of the injection pulse.

When the throttle valve opening changes as shown in the figure, the output of the air flow meter changes with a slight delay as shown in the figure. When there is no accelerating fuel, the pulse width gradually increases as the output of the air flow meter increases, as shown in injection pulse (1).

In the present invention, when the throttle valve opening changes, an accelerating fuel pulse is immediately output regardless of the 1200 signal.

The injection pulse (2) is an injection pulse obtained by subtracting the amount corresponding to the amount sucked into the cylinder by the acceleration fuel from the pulse width that would normally be output if there was no acceleration fuel, and the actual injection pulse is Fuel pulse and injection pulse (2)
The injection pulse (6) is obtained by adding the following.

〔Effect of the invention〕

As explained above, in the present invention, the fuel supply amount is controlled including the dynamic characteristics of the fuel control system, and a state in which the required fuel amount of the engine rapidly increases is detected, and in that case, acceleration fuel is immediately supplied. With this configuration, fuel can be increased without delay even in a transient state such as during sudden acceleration, and the air-fuel ratio can be controlled to a desired air-fuel ratio.

In the present invention, by supplying the amount of accelerating fuel minus the amount taken into the cylinder, it is possible to prevent excess fuel from accelerating fuel and to always maintain a stable air-fuel ratio. It has the excellent effect of being able to

[Brief explanation of the drawing]

Fig. 1 is a diagram of an example of a conventional fuel control device, Fig. 2 is a block diagram showing the overall configuration of the present invention, Fig. 6 is a block diagram of an embodiment of the present invention, and Fig. 4 is a control diagram of the present invention. FIG. 5 is a waveform diagram showing changes in intake air amount and fuel amount, and FIG. 6 is a signal waveform diagram of an embodiment of the present invention. Explanation of symbols 1... Air cleaner 2... Intake pipe 6... Throttle valve 4... Air flow meter 5...
...Fuel injection valve 6.Cylinder 7..Rotation sensor 8..Computation device 9°"°Throttle switch 10..Computation device 11..Input/output device 12, =
CPU 13...RAM 14...ROM 1[]0 ・Sensor 101 that detects intake air amount...
Memory 1 [12] for storing the dynamic characteristics of the air system; calculation means 103 for calculating the actual intake air amount; sensor 1 []4 for detecting engine operating variables; memory 105 for storing the dynamic characteristics of the fuel system;・Calculation means 1 for calculating the amount of fuel to be supplied
06... Means 10 for detecting a state in which the required fuel amount increases rapidly
7.Fuel signal generation means 108.Fuel supply means 109.Calculation means for calculating the amount of fuel sucked into the cylinder by accelerating fuel.Representative Patent Attorney Junnosuke Nakamura 2 O 2 Figure 3

Claims (1)

[Scope of Claims] (1) A first sensor that outputs an air amount signal related to the intake air amount of the internal combustion engine, and one or more second sensors that detect engine operating variables other than the intake air amount; A first storage means for storing a dynamic characteristic Ga between the air amount signal and the amount of intake air actually taken into the cylinder, and a relationship between the amount of fuel supplied and the amount of fuel actually taken into the cylinder. The dynamic characteristic Gf of
a second storage means for storing the actual intake air amount; a first calculation means for calculating the actual intake air amount from the air amount signal and the dynamic characteristic Ga of the air system; A second method that calculates the fuel amount required by the internal combustion engine at that time from the intake air amount and the output of the second sensor, and determines the amount of fuel to be supplied from the required fuel amount and the dynamic characteristic Gf of the fuel system. and a detection means for detecting a state in which the required fuel amount of the internal combustion engine rapidly increases. Under normal conditions, the second calculation means outputs a fuel signal corresponding to the fuel amount calculated by the second calculation means. The device according to the present invention, comprising fuel signal generating means for immediately outputting an acceleration fuel signal when the detecting means detects the above state, and means for supplying fuel in accordance with the output signal of the fuel signal generating means. (2) A first sensor that outputs an air amount signal related to the intake air amount of the internal combustion engine, one or more second sensors that detect engine operating variables other than the intake air amount, and the air amount signal and the cylinder. a first storage means for storing a dynamic characteristic Ga between the amount of intake air actually taken into the ring, and a dynamic characteristic Of between the fuel supply amount and the amount of fuel actually taken into the seventh ring;
a second storage means for storing the actual intake air amount; a first calculation means for calculating the actual intake air amount from the air amount signal and the dynamic characteristic Ga of the air system; Calculating the required fuel amount of the internal combustion engine at that time from the intake air amount and the output of the second sensor, calculating the fuel amount to be supplied from the required fuel amount and the dynamic characteristic Of of the fuel system, and
a second calculating means for calculating the amount of fuel to be supplied according to the value obtained by subtracting the fuel amount calculated by the sixth calculating means from the required fuel amount when the following acceleration fuel is supplied; a detection means for detecting a state in which the required fuel amount suddenly increases; a sixth calculation means for calculating the amount of fuel actually drawn into the cylinder by the acceleration fuel described below from the dynamic characteristic Gf of the fuel system; a fuel signal generating means for outputting a fuel signal according to the amount of fuel calculated by the second calculating means, and immediately outputting an acceleration fuel signal when the detecting means detects the above state; and a nuclear fuel signal generating means. and means for supplying fuel in response to an output signal. (b) The irradiation according to claim 2, wherein the fuel signal generating means outputs an acceleration fuel signal of a constant value when the detecting means detects the condition described in 2. Device. (4) When the detection means detects the above-mentioned condition, the fuel signal generation means responds to the degree of increase.