KR930012226B1 - Control method for a fuel injection engine - Google Patents

Abstract

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Description

How to control fuel injection of the engine

1A is a configuration diagram of a fuel injection control device to which the present invention is applied.

1B is a flowchart of a fuel injection control procedure in the computer (1).

2 shows the movement of intake air and fuel in the intake tract.

3 is a configuration diagram of a fuel injection control system.

4 is a flowchart of normal calculation processing and intermediate intervention processing.

5 is a timing diagram showing a time relationship between one stroke and one cycle.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control method for an engine used in a vehicle such as an automobile, and more particularly, to a fuel injection control method for estimating an amount of a liquid film attached to a wall of an intake pipe and determining a fuel injection amount based thereon.

The fuel injected from the fuel injection valve is attached to the wall of the intake pipe or the fuel made of the liquid film evaporates and is sent to the fuel chamber (cylinder), so that the injected fuel is not directly supplied to the fuel chamber. In the city, the amount of fuel supplied to the engine is greatly out of the required amount of fuel at that time.

As a conventional technique for solving this problem, a method of estimating the amount of fuel attached and determining the fuel injection amount has been considered (a conventional example: a method for controlling the fuel injection amount of a Japanese Toyota Motor Co., Ltd., a fuel injection engine). Japanese Patent Publication No. 58-8238). In this method, the basic fuel injection time is determined in accordance with the intake pipe pressure and the engine speed, and the amount of liquid film in the intake pipe is estimated based on the fact that fuel has been injected for that time. However, the amount injected in the intake engine is the fuel injected when the injection valve is opened for not only the basic fuel injection time but also the execution fuel injection time calculated by the amount taken into the engine fuel chamber, the amount of fuel attached, the feedback correction factor, and the like. Therefore, as a method of estimating the amount of the liquid film attached to the intake pipe, the actual amount of the liquid film is accurately estimated unless the amount of the injected fuel is fed back to the wall of the intake pipe. Can not calculate In the conventional estimation method, the amount of the liquid film cannot be estimated accurately for the above reason, and as a result, the amount of fuel supplied to the engine is different from the required amount of fuel at that time because the fuel injection amount does not consider the amount of the liquid film. there was.

In the conventional fuel injection control method for estimating and controlling a liquid film, there is a method of determining the execution fuel injection amount by subtracting the amount taken from the amount of the liquid film to the fuel chamber as the basic fuel injection amount and adding the deposition amount. (For example, Japanese Patent Publication No. 58-8238). At this time, the amount of fuel adhering to the wall surface of the injected fuel amount is a property that cannot be accurately determined unless the actual fuel injection amount is determined. In the conventional example, the amount of fuel adhering to be attached to the wall surface was determined based on the basic fuel injection time. However, in this method, a part of the fuel amount actually injected is not attached to the wall of the intake pipe. There was a problem that determination of (fuel adhesion amount) could not be made.

The first object of the present invention is when the amount of liquid film attached to the wall surface, the adhesion rate which is the ratio of the liquid film to the wall surface of the injection fuel and the evaporation rate which is the rate at which the liquid film evaporates from the wall surface are calculated from various sensor data. In addition, the present invention provides a method of determining the fuel injection amount such that the ratio of air to fuel entering the fuel chamber is a desired value.

A second object of the present invention is to provide a method for accurately estimating the amount of the liquid film attached to the wall of the intake pipe so as to determine the fuel injection amount so that the amount of fuel supplied to the engine always matches the required fuel amount.

In order to achieve the above first object, in the present invention, the amount of fuel to be injected into the fuel chamber without being attached to the wall surface and the amount of fuel to be added to the fuel chamber by evaporation of the liquid film into the fuel chamber is the amount of fuel actually entering the fuel chamber. Inject the fuel so that it is at the desired rate depending on the air flow mass. Further, in order to achieve the second object, the calculated value of the amount of fuel taken into the engine fuel chamber in one cycle period is subtracted from the amount of liquid film fuel on the wall of the intake pipe, which is estimated before one cycle. In addition, the calculated value of the intake pipe wall attachment amount per cycle is added according to the execution injection volume per stroke of the engine injected closest in time at the time point before one cycle.

Next, an embodiment of fuel injection control according to the present invention will be described with reference to FIGS. FIG. 1A shows a configuration diagram of an apparatus related to fuel injection control. In FIG. 1A, a hot wire air flow meter 2 detects an air flow mass of an intake pipe, and inputs it from a gks throttle angle sensor 3 to a computer 1. The throttle angle is the pressure in the suction pipe from the pressure sensor 4, the water temperature from the water temperature sensor 5, and the engine speed from the crank angle sensor 6, the oxygen (O ₂ ) sensor (7). From now, two air-to-fuel ratio signals are obtained and input to the computer 1, respectively. The computer 1 instructs the injector 8 the fuel injection amount.

In the computer 1, as shown in FIG. 1B, first, in step 101, the deposition rate of the fuel injection amount to the suction engine wall surface and the evaporation rate of the liquid film adhered to the suction engine wall surface are determined according to the data taken. It calculates according to (1) and (2) Formula. When the adhesion rate is x and the evaporation rate is 1 / τ, the adhesion rate x is simply a relationship between the throttle angle θth, for example.

It becomes On the other hand, the evaporation rate is a function of the water temperature Tw,

23도 c일 때, 1/τ=0.026으로 한다.It becomes Only Tw

At 23 degrees c, 1 /? = 0.026.

Next, using the adhesion rate x and evaporation rate 1 / τ obtained in step 102, the amount of the liquid film at the present time is calculated as follows from the amount of the liquid film before one cycle and the amount of fuel actually injected.

는 실제로 분사된 연료량을 단위 시간당의 연료량으로 환산한 것이다.Where? Is the calculation cycle time, Mr is the amount of the liquid film, Gr is the injection fuel amount,

Is the amount of fuel injected is converted into the amount of fuel per unit time.

In step 103, the fuel injection amount per unit time is determined as follows using the above adhesion rate and the amount of the liquid film. Since the fuel injection amount of the engine should be an amount corresponding to the intake air amount, the target value of the fuel amount to be supplied to the fuel chamber is as follows.

Where Q _a is the intake air amount and (A / F) is the ratio of the target air to fuel. In addition, G ^* _fe is a target value of the amount of combustion to enter the fuel chamber. FIG. 2 shows how the amount of fuel entering the combustion chamber of the engine is in the intake engine. As shown in FIG. 2, when the injected amount is G _f , the amount of fuel to be attached to the suction pipe wall 21 is X · G _f , and the amount of fuel supplied to the combustion chamber without being attached is (1-X) G. _f . In addition, the fuel amount (liquid film amount) M _{f which} becomes a liquid film and adheres to the intake pipe wall 21 is evaporated and the fuel supplied to the fuel chamber is M _f / τ. Therefore, when the quantity of fuel supplied to a combustion chamber is _Gfe , it becomes as follows.

If this G _fe is equal to the amount of fuel G ^* _fe to be supplied to the combustion chamber, the target ratio of air to fuel can be achieved. So, equation (4) and (5) are the same

You can do The amount of fuel to be injected so that the equation is satisfied may be determined to G _f. therefore,

를 구하여 상기 연소실에 공급하여야 할 연료량에서 감산하고, 그것을 분사하는 연료가 부착하지 않고 연소실로 공급되는 비부착율(1-X)로 나누는 것에 의해 단위 시간당의 연료량을 결정한다.It becomes Formula (7) is calculated | required as follows. The amount of fuel Q _a / (A / F) to be supplied to the combustion chamber is calculated so as to be the desired ratio of air to fuel according to the intake air quantity Q _a , and the amount of fuel taken from the evaporation rate 1 / τ and the amount of liquid film Mr to the combustion chamber

The amount of fuel per unit time is determined by subtracting from and subtracting from the amount of fuel to be supplied to the combustion chamber and dividing by the specific adhesion rate (1-X) supplied to the combustion chamber without the fuel injecting it.

Since G _f found in step 103 is the fuel injection amount per unit time, in step 104 G _f is converted into the fuel injection time per stroke of the engine.

Where N is the engine speed, K ₁ is a coefficient determined by the characteristics of the injector, γ is a correction coefficient fed back by the O ₂ sensor signal, and Ts is an invalid injection time.

T ₁ is the fuel injection time per stroke updated every operation cycle, but what is actually injected is the injection time T ₁ produced when an intermediate intervention signal occurs every stroke. Therefore, the data of the fuel injection amount for which the computer calculates the amount of the liquid film in the next cycle feeds back the actually injected time to the next amount which becomes the fuel amount per unit time.

Equation (9) is used as Equation (3) in the following operation cycle.

3 is a block diagram of a fuel injection control system in the computer 1 of FIG. 1A. In FIG. 3, the fuel injection amount G _f per unit time is calculated by the calculation unit 12 in accordance with the liquid film and the air flow rate mass estimated by the estimated calculation unit 13 of the amount M _f of the liquid film attached to the intake pipe wall surface. Is calculated.

In accordance with the signal generated by the O ₂ sensor 7, the feedback correction coefficient δ = f (O ₂ ) of the air-to-fuel ratio, which targets the theoretical air-to-fuel ratio, is calculated by the calculation unit 14. In the calculation unit 11, the fuel injection amount per stroke is calculated as follows.

Here, K is a coefficient which is converted into the fuel injection amount per stroke or is determined by the characteristics of the injector, and Ts is an invalid injection time.

The estimation unit 13 calculates the amount of the liquid film in the intake pipe as follows.

Here, M _{f on the} right side is the amount of the liquid film before one cycle, and M _{f on the} left side is the amount of the newly estimated liquid film. 1 /? Is the evaporation rate of the liquid film, and X is the rate of adhesion to the intake pipe wall surface among the amounts of fuel injection (referred to as the adhesion rate). ΔT is one cycle time at which the block diagram of FIG. 3 is calculated. Thus, on the right side

Is the amount of liquid film evaporated and taken to the combustion chamber in one cycle time. In addition, of Clause 2 of the right side of Formula (11)

에 대해서는, 1행정당의 시간과 계산의 1주기 시간과의 시간적 관계도 있으므로, 다음에 기술하지만, 피이드 백 보정계수 γ를 곱하여 산출된 단위시간당의 연료 분사량 γ·G_f가 1행정 개시의 신호가 크랭크 각도 센서에 왔을 때 갱신되는 단위시간당 분사된 연료량이다. 부착율 x나 증발율 1/τ(τ는 증발시 정수이다)는 쓰로틀 각도 θth, 수온 TW, 압력 P, 공기유량질량 Q_a등에서 실험적으로 얻어지는 것이지만, 본 실시예에서는, 간단히 표시하기 위해서, 부착율 X는 쓰로틀 각도의 함수로서,Is the amount of fuel attached in one cycle time among the fuel amounts per unit time actually injected.

Since there is also a temporal relationship between the time per stroke and the one cycle time of the calculation, the fuel injection amount γ · G _f per unit time calculated by multiplying the feedback correction coefficient γ is described below. The amount of fuel injected per unit time updated when it comes to the crank angle sensor. Although the adhesion rate x and the evaporation rate 1 / τ (τ is an integer at the time of evaporation) are experimentally obtained at the throttle angle θth, the water temperature TW, the pressure P, the air flow mass Q _a, and the like, in the present example, the adhesion rate is used for simplicity. X is a function of the throttle angle

Shall be. Evaporation rate, on the other hand, is a function of water temperature

23도 c일 때, 1/τ=0.0266으로 한다.Shall be. Tw

At 23 degrees c, 1 /? = 0.0266.

의 루프가 2중으로 겹쳐 있는 것이 특징이다.As described above, as can be understood from FIG. 3, as a structure of the control system, the feed back loop of the correction coefficient γ fed back by the O ₂ sensor signal and the amount of fuel injected by the fuel injection are calculated. Fuel injection volume

The loops of are overlapped twice.

의 메모리에 넣는다. 이 처리는 제3도의 분사 동기부(15)에서 행하여지지만, 그 타이밍은 제4도의 스텝(32)에 도시한 것과 같이, 중간 개입 신호 INT가 왔을 때이다. 이상과 같은 동작을 행하게 하므로써, 실제로 분사한 양이 피이드 백 되어 액체막을 정확하게 추정하기 위해서 사용된다.Next, the timing of injection per one stroke and the timing of the calculation cycle will be described. Calculation shown in FIG. 3 is performed for every one stroke period T, and the injection timing adjustment part 16 of FIG. 3 is updated in step 31 of FIG. 4 every cycle. However, the actual injection is started by the intermediate intervention signal INT which comes every stroke. Therefore, as shown in FIG. 5, the injection time T ₁ calculated closest to the actual _one is actually injected. Then, in FIG. 5, (a) is the intermediate intervention signal for each one stroke, (b) the injection pulse width, (c) are each displayed with a time lapse of the γ · G _f is calculated. In the case of the present invention is the interrupt signal comes, the γ · G _f, which is calculated at that point,

Into your memory. This process is performed by the injection synchronizer 15 of FIG. 3, but the timing is when the intermediate intervention signal INT comes in, as shown in step 32 of FIG. By performing the above operation, the amount actually sprayed is fed back and used to accurately estimate the liquid film.

According to the present invention, the lean spike at the time of acceleration and the rich spike at the time of deceleration are eliminated as compared with the method for determining the basic fuel injection amount according to the amount of intake air as is conventionally performed. This improves the operability at the time of acceleration and the removal of harmful gas at the time of deceleration effectively. Therefore, the amount of the three-way catalyst can be reduced, which makes it economically effective. In order to cope with acceleration and deceleration, in the past, various memory maps for acceleration correction and deceleration correction have been prepared based on changes in throttle angle, and the numerical values of the map have to be searched. According to the present invention, acceleration correction and deceleration correction are performed by matching only the deposition rate of the fuel injection and the evaporation rate of the liquid film at the acceleration-deceleration air-to-fuel ratio, thereby making the production process more efficient.

Furthermore, according to the present invention, in order to estimate the amount of the liquid film adhering to the wall of the intake pipe, the amount of the liquid film is newly estimated using the fuel injection amount actually injected. The amount of liquid film is estimated. In consideration of this estimated amount of liquid film, by using the method of determining the fuel injection amount, it is possible to control the air-to-fuel ratio of the mixed gas supplied to the engine close to the theoretical air-to-fuel ratio even during acceleration and deceleration. As a result, exhaust gas purification and operation performance can be improved.

Claims (2)

In the method of controlling the fuel injection amount of the engine in accordance with the intake air amount, the deposition rate X of the injected fuel to the intake pipe wall surface and the evaporation from the attached liquid film are calculated as 1 / τ, and the calculated X and 1 / τ are calculated. And the amount M _f of the liquid film at the present time is calculated from the fuel injection amount G _f injected last time, and the target fuel amount Qa / (A / F) to be supplied to the combustion chamber from the intake air amount Q _a and the target value A / F of the air-to-fuel ratio. Calculate the fuel injection quantity G _f

The fuel injection control method of the engine characterized by the above-mentioned. The fuel injection amount per one stroke of the engine is determined at a certain period, and the calculated fuel amount taken to the engine combustion chamber in one cycle period is subtracted from the fuel amount of the liquid film on the wall of the intake pipe, which is estimated one cycle before. According to the execution injection amount, the calculation value of the intake pipe wall surface adhesion amount per cycle is added to the said liquid film fuel amount, and the intake engine by the fuel injection amount feedback is estimated by calculating the liquid film fuel charge of the wall surface of the intake pipe at this time. Estimation method of liquid film fuel amount on wall surface.

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