JPH04252835A - Fuel injection controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To compensate an injection quantity conformed to the heavy-light type of fuel and the deposit of a intake system. CONSTITUTION:A means 103 judging the start-up state of engine speed at the time of engine starting, a means 104 learning a fuel correction value from this start-up state and engine cooling water temperature, and a means 105 compensating a fuel injection quantity according to this learning value are all installed in a fuel control system 102 of an internal combustion engine which controls fuel injection out of a fuel injection system 101 on the basis of the detected value of a sensor 100 detecting an engine's driving state. Since heavy- light type of fuel and the presence of deposit are judged from the engine speed start-up state at the time of starting, and thereby the fuel injection quantity is learned and compensated, the fuel injection quantity is always controllable so properly.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine.

0002

2. Description of the Related Art In a fuel injection engine, the fuel injection amount (injection pulse width) Tst at the time of starting is calculated and controlled, for example, by the following equation.

Tst=Tsto×Kvb×Kne Here, Tsto is the basic injection amount at the time of starting, and is determined according to the engine cooling water temperature Tw. Kvb is a voltage correction coefficient determined according to the battery voltage, and Kne is a rotation speed correction coefficient determined according to the engine rotation speed.

[0004] Normal fuel injection amount (injection pulse width) Te
is calculated and controlled, for example, by the following equation.

[0005] Te=Tp×α×K×Coef where, T
p is the basic injection amount (base air-fuel ratio) determined according to the engine intake air amount Qa and engine speed N, and α is the difference between the actual air-fuel ratio (oxygen concentration in exhaust gas) and the target air-fuel ratio. The feedback correction coefficient K calculated based on this is a learning control coefficient for correcting subtle changes in the base air-fuel ratio. Further, Coef is the sum of the air-fuel ratio correction coefficient in the operating range, the water temperature increase correction coefficient, the post-start increase correction coefficient, etc. (see Japanese Patent Laid-Open No. 58-27844, etc.).

[0006]

[Problems to be Solved by the Invention] In this kind of control, if the properties of the fuel supplied to the tank are different, or if deposits are attached to the intake valve or intake port wall of the engine, the response and mixing of the fuel may be affected. This will affect the generation of energy, etc.

[0007] That is, if heavy fuel has low volatility, it is difficult to vaporize compared to light fuel, so there is a relative shortage of fuel in the engine cylinder during transient times. In addition, some of the injected fuel from the fuel injection device may adhere to the intake port wall, etc., or flow along the port wall while remaining in liquid form (these are referred to as fuel adhesion). If heavy fuel is used, or if there are deposits on the intake port wall, etc., the amount increases accordingly, and intake into the engine cylinders is significantly delayed.

For this reason, as shown in FIG. 11, when using a specified light fuel with no deposits, a smooth start-up of the engine rotation is obtained at the time of starting, but when using heavy fuel or when there are deposits, the engine speed becomes unstable at the time of starting. There is a problem that it is difficult to obtain a certain combustion and the rotation fluctuates greatly. Furthermore, if heavy fuel is used or there is deposit, there is a problem in that the air-fuel mixture becomes lean during acceleration, resulting in poor acceleration.

[0009] Therefore, good startability and drivability cannot be obtained, and fuel economy and exhaust emissions are also impaired.

[0010] Although there are methods for detecting fuel properties based on the specific gravity, dielectric constant, etc. of the fuel, these methods are difficult to apply because they cannot accurately detect the heavy and light components of the fuel. Also,
Although it has been considered to measure differences in fuel properties from air-fuel ratio control and feed it back to fuel injection amount control, such control is difficult to perform.

[0011] The present invention aims to solve these problems by appropriately controlling the fuel by determining whether the fuel is heavy or light and the presence or absence of deposits from the rising state of engine rotation at the time of starting. There is.

0012

[Means for Solving the Problems] As shown in FIG. 1, the present invention provides fuel for an internal combustion engine that controls the amount of fuel injected from a fuel injection device 101 based on the detected value of a sensor 100 that detects the operating state of the engine. The control system 102 includes a means 103 for determining a rising state of engine rotation when starting the engine, a means 104 for learning a fuel correction amount from this starting state and the engine cooling water temperature, and a means 104 for correcting the fuel injection amount according to the learned value. and means 105 for doing so.

[0013]

[Operation] If the fuel is heavy or there are deposits in the intake system, the engine speed will be slow to start and the rotational fluctuations will be large when the engine is started. Therefore, it is possible to judge whether the fuel is heavy or light and whether there is a deposit from this start-up state, and by learning and correcting the fuel injection amount according to the start-up state and the engine cooling water temperature, the fuel injection amount can always be controlled appropriately. .

[0014]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

As shown in FIG. 2, intake air passes through an intake pipe 3 from an air cleaner 2, and fuel is injected from an injector (fuel injection device) 4 provided in each cylinder toward each intake port of the engine 1. .

The gas combusted in the cylinder is introduced into a catalytic converter 6 through an exhaust pipe 5, where harmful components (CO, HC, NOx) in the combusted gas are purified by a three-way catalyst and discharged.

The intake air flow rate Qa is detected by a hot wire type air flow meter 7, and the flow rate is controlled by a throttle valve 8 which is linked with an accelerator pedal.

The opening TVO of the throttle valve 8 is detected by a throttle opening sensor 9, and the rotational speed N of the engine 1 is detected by a crank angle sensor 10. Further, the cooling water temperature Tw of the water jacket is detected by a water temperature sensor 11, and the air-fuel ratio (mixture ratio) in the exhaust gas is detected by an air-fuel ratio sensor 12.

Detection signals from an air flow meter 7, a throttle opening sensor 9, a crank angle sensor 10, a water temperature sensor 11, an air-fuel ratio sensor 12, and an ignition switch (not shown) as sensors for detecting the operating state of the engine, as well as battery voltage. The signal is input to control unit 20.

The control unit 20 serving as the start-up state determining means, the fuel correction amount learning means, and the fuel injection amount correcting means is constituted by a microcomputer including a CPU, RAM, ROM, I/O device, etc. The fuel injection amount from the injector 4 is controlled based on the following.

Next, the control details of the control unit 20 will be explained.

The fuel injection amount (injection pulse width) Tst at the time of engine starting is determined by adding the voltage correction coefficient Kvb, the rotational speed correction coefficient Kne, and the learning correction to the basic injection amount Tsto at the time of starting, as shown in FIG. 3 (steps 11 to 15). It is determined by multiplying the value Kfuel, and is controlled by outputting the injection pulse signal to the injector 4.

Tst=Tsto×Kvb×Kne×Kfue
(1) The basic injection amount Tsto at startup is determined from a table determined according to the engine cooling water temperature Tw, the voltage correction coefficient Kvb is determined from a table determined according to the battery voltage, and the rotational speed correction coefficient Kne is determined from a table determined according to the engine cooling water temperature Tw. It is read from a table determined according to the engine rotation speed N. The learning correction value Kfuel will be described later.

[0024] Normal fuel injection amount (injection pulse width) Te
is the basic injection amount Tp (base air-fuel ratio) determined according to the engine intake air amount Qa and the engine rotational speed N, as shown in the following equations (2) and (3), and the detection by the air-fuel ratio sensor 12. Feedback correction coefficient α based on the difference between the value and the target air-fuel ratio, base air-fuel ratio learning control coefficient K, various correction coefficients C
It is determined by multiplying oef and is controlled by outputting the injection pulse signal to the injector 4.

Te=Tp×α×K×Coef
‥‥‥(2) Coef={(Kmr+Ktr
m)+Ktw+(Kas×Kfuel)+
Kf−Kdc}×Kst‥‥
(3) Here, Kmr and Ktrm in Coef are the air-fuel ratio correction coefficients in the operating range, Ktw is the water temperature increase correction coefficient, and Ka
s is the increase correction coefficient after starting, Kf is the correction coefficient at low water temperature, K
dc is a reduction correction coefficient during deceleration, and Kst is an increase correction value during starting, each of which is read from a predetermined table. Also,
The learning correction value Kfuel is added to the correction term of Kas.

On the other hand, the learning correction value Kfuel is learned as follows from the rising state of rotation at the time of starting the engine.

First, when the engine is started as shown in FIG. 4, if the flag FLGST is "0" when the ignition switch returns from the start position to the ON position,
As shown in FIG. 5, the rise time Tmst between the predetermined rotational speeds Nel and Neh of the rotational speed Ne is measured, and the flag FLGST is set to "1" (steps 21 to 27).

Next, from the water temperature Tw at the time of starting, the starting time reference Tmsto (rise reference time between the rotational speeds Nel and Neh) is calculated as the water temperature reference time Tmst as shown in the following equation (4).
It is obtained by multiplying tw by the correction time Tmstvb based on the battery voltage Vb.

Tmsto=Tmsttw×Tmstvb (4) That is, read the water temperature reference time Tmsttw from the table in which reference data is determined as shown in FIG. 6 based on the water temperature Tw,
Based on the battery voltage Vb, read the voltage correction time Tmstvb from a table such as that shown in FIG. 7, and set the starting time reference Tm.
sto is calculated, and the difference ΔTmst between the rise time Tmst and the starting time reference Tmsto is determined (steps 28-
30).

Then, from this difference ΔTmst, the learning correction value Kfuel is determined by reading from the table defined as shown in FIG.

That is, the slower the rise of the rotation Ne when starting the engine is and the larger the difference from the starting time reference Tmsto based on the water temperature Tw, the larger the learning correction value Kfuel is taken. In addition, if the rotation Ne starts up smoothly and the difference from the starting time reference Tmsto is small, the learning correction value Kfue
l becomes a small value.

Note that the flag FLGST is set to "0" when the fuel tank is refilled.

Because of this configuration, if the refueled fuel is heavy fuel or if there is a deposit on the intake port wall, etc., there will be a shortage of fuel injected from the injector 4 or a delay in response when starting the engine after refueling. As a result, the start-up of the engine rotation is delayed (see FIG. 11), but at this time, the predetermined starting time reference Tms of the rotation start-up time Tmst is
A fuel correction value Kfuel is learned based on the difference from to.

From the next start, the fuel injection amount Tst (formula (1)) is corrected using the learning correction value Kfuel, and the fuel injection amount of the injector 4 at the time of start is controlled based on the corrected Tst. be done.

[0035] Therefore, it is possible to control the appropriate injection amount of fuel according to the heavy/light quality of the fuel and the state of deposits, thereby ensuring good starting performance with little fluctuation in engine rotation and smooth start-up. can.

On the other hand, the fuel injection amount Te (formulas (2), (3)) is also corrected by the learning correction value Kfuel, and the normal fuel injection amount of the injector 4 is controlled based on the corrected Te. .

In other words, in the case of heavy fuel or if there are deposits, the mixture may become lean during acceleration etc. even if feedback control of the air-fuel ratio is performed, but correction based on the heavy/light quality of the fuel and deposits Since the fuel injection amount is corrected using the value Kfuel, proper injection can be performed without delay in fuel supply during acceleration or the like.

For this reason, feedback control of the air-fuel ratio,
It is possible to obtain good acceleration while reducing the burden of learning control, resulting in significant improvements in drivability, fuel efficiency, and exhaust performance.

The correction value Kfuel is learned each time the engine is refueled, but the learning may be performed several times each time the engine is started after refueling, and the correction value Kfuel may be corrected or updated each time the learning is performed.

Furthermore, in the embodiment, the learning correction value Kfuel
is added to the correction coefficient Coef to correct the normal fuel injection amount Te. However, in the case of interrupt injection during acceleration, for example, it is also possible to correct the interrupt injection amount using the learning correction value Kfuel. be.

FIGS. 9 and 10 show another embodiment of the present invention, in which the learning correction value Kfuel is learned from the fluctuation state of the rotation when the engine is started.

In this case, when the engine is started, the moving average value Neav during the time when the engine speed rises from a predetermined rotational speed Ne1 to Neh is calculated, and the difference ΔNe between the instantaneous value Ne and the moving average value Neav is integrated. , its variance En
Find e (steps 41-51).

Then, the learning correction value Kfuel is read from the table in FIG. 8 and determined from this variance value Ene (after correction based on the water temperature Tw). The larger the variance value Ene, that is, the rotational fluctuation, the larger the learning correction value Kfuel is taken.

That is, in the case of heavy fuel or if there are deposits, the startup of the engine rotation will be delayed and the fluctuations in the rotation will be large when starting the engine. From this rotation fluctuation, the heavy/light quality of the fuel and the state of the deposits can be determined. As a result, the correction value Kfu
el can be determined accurately.

[0045]

As described above, according to the present invention, a fuel control system for an internal combustion engine that controls the amount of fuel injected from a fuel injection device based on a detected value of a sensor that detects the operating state of the engine is used to control engine startup. The present invention is equipped with means for determining the start-up state of engine rotation, means for learning the fuel correction amount from this start-up state and engine cooling water temperature, and means for correcting the fuel injection amount according to this learned value. Regardless of whether the engine is heavy or light or whether there are deposits on the intake port wall, the fuel injection amount can be controlled appropriately, ensuring good engine startability and drivability, and significantly improving fuel efficiency and exhaust emissions. can.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a configuration diagram showing a control system.

FIG. 3 is a control flowchart for calculating the fuel injection amount at startup.

FIG. 4 is a control flowchart for determining a start-up state of rotation.

FIG. 5 is an explanatory diagram showing an example of measuring the rise time of rotation.

FIG. 6 is a characteristic diagram showing the relationship between water temperature and starting time reference.

FIG. 7 is a characteristic diagram showing voltage correction data.

FIG. 8 is a characteristic diagram showing data of learning correction values.

FIG. 9 is a control flowchart of another embodiment.

FIG. 10 is an explanatory diagram showing an example of measurement of rotational fluctuations.

FIG. 11 is an explanatory diagram showing a rising state of rotation at the time of starting.

[Explanation of symbols]

1 Engine 4 Injector 7 Air flow meter 9 Throttle opening sensor 10 Crank angle sensor 11 Water temperature sensor 12 Air fuel ratio sensor 20 Control unit

Claims (3)

[Claims] Claim 1: In a fuel injection control device for an internal combustion engine that controls the amount of fuel injected from a fuel injection device based on a detected value of a sensor that detects the operating state of the engine, a rising state of engine rotation is determined at the time of starting the engine. A fuel injection control device for an internal combustion engine, comprising: means for learning a fuel correction amount from the start-up state and engine cooling water temperature; and means for correcting the fuel injection amount according to the learned value. . 2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the start-up state determination means detects a start-up time between predetermined rotational speeds and determines the start-up state based on this time. . 3. The start-up state determining means detects rotation fluctuation by integrating the difference between the instantaneous value and the moving average value of the rotation speed, and determines the start-up state from this rotation fluctuation. The fuel injection control device for the internal combustion engine described above.