JPS59145357A - Fuel control device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce the deviation in air fuel ratio from the target value even at the time of transient condition by controlling the quantity of air and the quantity of fuel actually sucked into a cylinder based on the previously measured and stored dynamic characteristic of the air system and the fuel system. CONSTITUTION:A suction air quantity operating section 10 calculates the actual suction air quantity from an air quantity signal S1 provided from an air flow meter 4 and the dynamic characteristic of an air system which is previously obtained by an experiment and stored, and outputs a suction air quantity signal S4 corresponding to the calculated value. A fuel operating section 11 calculates from this signal the required quantity of fuel at the time, and calculates the quantity of fuel from this value and the dynamic characteristic of a fuel system previously obtained by an experiment, outputting a fuel feed signal S5. Thereby a fuel injection valve 5 can be controlled enabling a control in line with the actual suction air quantity and fuel quantity at the time of transient condition, and thereby, the air fuel ratio can be maintained at the target value.

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 fuel control device for an internal combustion engine, and in particular to a fuel control device for an internal combustion engine.
The present invention relates to a technique for correcting unevenness in supply Jil.

C) Prior art) As an example of a conventional fuel control device, there is one shown in FIG.
5165. 55-134718, etc.).

In Fig. 11, ■ is the air cleaner, 2 is the intake pipe, and 3 is the air cleaner.
4 is a throttle valve, 4 is an air flow meter that outputs an air quality signal S1 corresponding to the amount of air passing through the intake pipe 2, 5 is a fuel injection valve that injects fuel according to a fuel injection amount signal S3, which will be described later, 6 7 is a cylinder, 7 is a rotation sensor that outputs a rotation signal S2 synchronized with the rotation of the crankshaft, and 8 is a rotation sensor that calculates the fuel injection amount corresponding to the operating state at that time mainly from the air arrival signal S1 and rotation signal S2, and the result is It is an arithmetic unit that outputs a fuel injection amount signal S3 according to
, RAM, ROM, Ilo, etc., and consists of an A-le microcomputer.

Calculations between fuel injections in the device 1- are performed as follows.

In other words, the air arrival signal Sl measured by the air flow meter 4
When the intake air ω obtained by
TI calculated by the formula (1) Note that the above coefficient is a coefficient for sealing correction according to the temperature of the internal combustion engine, etc.

As shown in equation (1), the fuel injection amount is set mainly according to the intake air amount and rotational speed, and the actual fuel injection amount is the one that is corrected by temperature, exhaust gas component concentration, etc. However, in the conventional device, the air arrival signal Sl of the air flow meter is used as it is as a signal indicating the amount of intake air, and the control is performed so that all the injected fuel is taken into the cylinder without any time delay.

In other words, in conventional devices, the air amount is the 7111:(1:' value itself) of the air flow meter, and the fuel amount is the fuel injected into the intake pipe, and the amount of air and fuel actually taken into the cylinder is controlled. It wasn't something I was doing.

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 in that it had a negative impact on performance, etc.

(Purpose of the Invention) The present invention has been made to solve the above problem, and is a method that corresponds well to the actual amount of intake air in the cylinder (hereinafter referred to as intake air amount) and the amount of fuel supplied. The object of the present invention is to provide a fuel control device that can perform accurate control.

(Summary of the Invention) In order to achieve the above object, the present invention calculates the intake air amount from the dynamic characteristics of the air system that have been measured and stored in advance and the air arrival signal S1 of the air flow meter. The fuel amount required by the internal combustion engine is calculated from the value, and the amount of fuel to be actually supplied is calculated from the required fuel amount described in the dynamic characteristics of the fuel system.

Furthermore, in the present invention, in addition to the value of the intake air amount in the current calculation, the next value is predicted, the required fuel amount of the internal combustion engine is calculated from both the current and next values, and the dynamic characteristics of the fuel system are calculated. The fuel amount to be actually supplied is calculated from the above-mentioned required fuel amount.

(Example of the invention) Hereinafter, the present invention will be described in detail based on Examples.

First, we will explain in detail the dynamic characteristics of the air system and fuel system based on Figure 2.

For example, when a throttle valve is opened and closed as shown in FIG. 2(A), a flap-type air flow meter (such as an airflow meter) outputs a signal as shown in FIG. 2(B).

At this time, the suction air temperature changes as shown in (C), VJcI.

On the other hand, the fuel is air IJi, depending on the sewing needle signal (B),
It is injected with a negligible delay time. However, since the injected fuel has dynamic characteristics different from those of air, the amount of fuel actually drawn into the cylinder is as shown by the solid line C2, which does not match the change in the amount of intake air.

Therefore, the air-fuel ratio becomes as shown in (D).

It deviates from the target value (for example, the stoichiometric air-fuel ratio).

FIG. 3 is a system diagram showing the above dynamic characteristics. In FIG. 3, the intake air ti A c (n) is expressed with respect to the air 70-meter output A a (r+) using a transfer function G a (z) that describes the dynamic characteristics of the air system.

A C (2) = G a (z) A a (2) ・ Fist
It can be expressed as @ (2). However, in equation 2), (n) indicates the control period, and n is now 1a+l, n
-1 indicates the previous control cycle, and n+1 indicates the next control cycle. Also A
c(z).

Aa(z) is two transformations of A c(n) and Aa(n), respectively, and is also a fixed alinum T p = K A
The actual intake fuel 11:Fc(n) of the cylinder for the fuel 41AFf(n) injected with the injection pulse width Tp calculated by a,/N is a transfer function that describes the dynamic characteristics of the fuel system. Using Gf(z), F c(z) = G f(z)F f(z)e@-(3
) can be expressed as However, F c(z), F f
(z) are respectively Fc(n) and Ff(n)'(7)
This is Z transformation.

In the above equations (2) and (3), G a(z) and G
If f(z) is not the same or different, the ratio between the amount of intake air and the amount of fuel in the cylinder will change in the transient state j9, and the air-fuel ratio will deviate from the target value.The present invention solves the above problem. This will be explained in detail below.

FIG. 4 is a diagram showing one embodiment of the present invention, and FIG. 1 and No. n show the same thing.

In FIG. 4, reference numeral 9 denotes a calculation device, including an intake air calculation unit 10, a combustion engine 4 calculation unit 11. It consists of storage units 12 and 13. Note that this configuration shows the contents of the arithmetic unit 9 by function, and in reality, it is configured by, for example, a microcomputer.

The intake air amount calculating section 10 calculates the amount of air from the air flow meter 4 to q-
The obtained air withdrawal signal St is determined in advance through an experiment and stored in the storage unit 12.
The actual amount of intake air is calculated from the dynamic characteristics of the air system stored in the memory, and the intake air arrival &tS4 corresponding to the calculated value is output.

The fuel calculation unit 11 calculates the required fuel amount at that time from the above-mentioned intake air signal S4, and further calculates the actual amount from the required fuel amount and the dynamic characteristics of the fuel system that have been determined in advance through experiments and stored in the storage unit 13. The fuel ω to be injected is calculated 7, and a fuel supply amount signal S5 corresponding to the calculated value is output.

By controlling the fuel injection valve 5 using this fuel supply amount signal S5, it is possible to perform control corresponding to the actual intake air amount and fuel acid of the cylinder even during a transient state, so that the air amount and fuel can be controlled at all times. It is possible to maintain a balance with the acid and maintain the air-fuel ratio at the target value.

Next, the operation in the arithmetic unit 9 will be explained in detail based on the flowchart 1 of the 1st and 5th IN.

In FIG. 5, the PI first reads the air lance signal Sl of the air flow meter 4, and converts its (d to Aa(n-
1). Note that n-1 indicates a value in the previous control cycle.

Next, in P2, a value Ac(n) of 1 is calculated for the intake air in the current control cycle. This calculation is performed 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 by, for example, a second-order pulse transfer function.

And A a(n-]) in -1-, it 2 times ago
A a, (n-2), the values of the intake air amount A c (n-1), A c (n-2), and 1: (
From formula 4), the current intake air μ is i17iAc(n),
It becomes as shown in equation (5) below.

A c(n)=dIA a(nl)+eIA a(
n-2)-bIA c(n-1)-c, A c(n-
2)... (5) The coefficient b1. c1. d1. If e is determined in advance through experiments, A c(n) can be determined by calculation.

Next, in P3, the next intake air amount value A c(n
+1) Perform the prediction calculation.

This A1r4 can be calculated by using, for example, an extrapolation formula and calculating A c(n+1.l=2 A c(n) - A c(
n-1). Note that A c(n+1)
The reason why the predictive calculation of is necessary will be described later.

Next, in P4, the intake air amount A c(n
), the current required fuel consumption (value F
Compute c(n).

A c(n) F c(n) = K□ ... (6) The required fuel amount F c(n) in F is the fuel actually required in the cylinder compared to the actual intake air amount. It is φ.

Next, in P5, using A c (n+1) obtained in P3,
The next required fuel 1QFc(n+1) is obtained by 1'J from the following equation (7).

A c(n+]) F c(n+1)=K □ ・(7) In rice cooking P6, -) Yasugi fuel mentioned in 2! - to cylinder (J4
9 of the fuel 1j-Ff(n) to be actually injected to supply the fuel.

For example, if the dynamic characteristic of the fuel system is Gf(z), then the fuel to be injected this time is Ff(n) as shown in equation (9) below.

+ c2F c(n-1)-e2F f(n l)]1
(9) Therefore, the above coefficient b2. C2, d2. If e2 is determined in advance by experiment, F f (n) can be determined by calculation.

Next, at P7, fuel injection is performed by driving the fuel injection valve 5 in accordance with the fuel type F f (n) to be actually injected, which is determined as described below.

By controlling as described in -1-, it is possible to always maintain a balance between the amount of intake air and the amount of fuel in the cylinder, so that the air-fuel ratio can always be maintained at the target value even during a transient state.

The reason why A c (n+1) was predictively calculated in P3 is to calculate F c (n+1) in P5, and F c (n+1) is necessary to calculate F and f (n) in P6. It has become.

In addition, in this example, the dynamic characteristics of the fuel system are described as in equation (8), so the predictive calculation of P3 of J2 is required. In cases where it can be expressed as a formula, for example, in formula (8), the denominator is b2z
1 so that only +c2z-2, Fc(n+j) in equation (9) becomes unnecessary,
Therefore, prediction calculation of A c (r++I) is also unnecessary.

It goes without saying that prediction calculations further ahead are also possible if necessary.

In addition, in the embodiment described in -1-, an air flow meter was used as a sensor for measuring the amount of intake air, but air wave meters such as a 5f variable vane type, hot wire type, Karman vortex type, etc. May be used.

Furthermore, the present invention can be applied in the same manner as described above even in the case of a method in which the amount of intake air is estimated from the intake negative pressure, the opening degree of the throttle valve, etc., without directly measuring the amount of intake air.

Note that the dynamic characteristics of the air system and fuel system G a (z), G f (
It is practical to describe the force z) in synchronization with the rotation of the internal combustion engine, and therefore it is preferable to perform the calculation in FIG. 5 in synchronization with the rotation.

Furthermore, the dynamic characteristics described above vary depending on the type of internal combustion engine and fuel supply system, and may also vary depending on the rolling range of the internal combustion engine, so it is preferable to have a plurality of them as necessary.

(Effects of the Invention) As explained above, according to the present invention, the amount of intake air and the amount of fuel that are actually drawn into the cylinder are taken into account the dynamic characteristics of the air system and fuel system that have been measured and stored in advance. Since it is configured to control the air-fuel ratio, it is possible to reduce the deviation from the target value of the air-fuel ratio even during transient conditions such as during acceleration and deceleration, thereby improving exhaust purification performance, fuel efficiency, driving performance, etc. It can make you feel better.

[Brief explanation of the drawing]

FIG. 1 is a diagram of an example of a conventional device, FIG. 2 is a characteristic side view of the device of FIG. 1, and FIG. 3 is a system diagram showing dynamic characteristics. FIG. 4 is a diagram showing an embodiment of the present invention, and FIG. 5 is a diagram showing an embodiment of a flowchart showing calculations of the present invention. Explanation of marks () 1 - Air cleaner 2... Intake pipe 3... Throttle valve 4... Air flow meter 5... Fuel injection valve 61/Cylinder 7111 Rotation sensor 8.9... Arithmetic unit lO ...Intake air amount calculation unit 11...Fuel calculation unit 12.13--Fist storage unit Patent attorney Junnosuke Nakamura

Claims (1)

[Scope of Claims] ■, a unit that outputs an air amount signal related to the intake air amount of the internal combustion engine; In a fuel control device 6 for an internal combustion engine, the fuel control device 6 includes a calculation stage that calculates and outputs a fuel signal corresponding to the calculation, and a fuel supply means that supplies the internal combustion engine with an amount of fuel corresponding to the fuel No. 4R described in 1-. , L
The dynamic characteristic Ga between the air quantity signal and the intake air actually taken into the cylinder/da is memorized, and the actual intake air quantity is calculated from the air quantity signal and the dynamic characteristic Ga of the air system. The calculation means calculates the dynamic characteristic Gf between the fuel signal written in I and the amount of fuel actually taken into the cylinder, and then calculates the amount of intake air obtained by the calculation in [2] at that time. calculation means for calculating the required fuel amount of the internal combustion engine, calculating the fuel φ to be supplied from the required fuel amount and the dynamic characteristic Gf of the fuel system, and outputting a fuel supply amount signal corresponding to the calculated value. , ■
A sensible heat device characterized in that the fuel supply means (1) is controlled by the fuel supply amount signal (1). 2. A sensor that outputs an air pressure signal related to the intake air amount of the internal combustion engine, and calculates the required fuel product of the internal combustion engine from the air amount signal and other engine operating variables and outputs a corresponding fuel signal. In a fuel control device for an internal combustion engine, which is equipped with an L stage and a fuel supply means for supplying an amount of fuel to the internal combustion engine according to the above fuel signal, the air acid signal and the Memorize the dynamic characteristic Ga between the amount of intake air inhaled and the air Fl ((rl
Calculating means for calculating the current intake air amount from the air flow rate and the dynamic characteristics Ga of the air system, and further predicting the next intake air amount, and calculating means for calculating the current intake air amount from the air system dynamic characteristic Ga Calculate the required fuel amount of the internal combustion engine using the current and next intake air amounts in [-], and calculate the fuel supply amount from the required fuel amount and the fuel system dynamic characteristics Gf. and calculation means for calculating the amount of fuel to be supplied and outputting a fuel supply amount signal corresponding to the value, and the fuel supply means is configured to be controlled by the fuel supply amount signal. Sensible heat equipment.