JP2712255B2 - Fuel supply control device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel supply control device for an internal combustion engine such as an automobile, and in particular, corrects a basic supply amount transiently according to a state immediately after the start of the engine. And an apparatus for determining an optimum fuel supply amount.

(Prior Art) In general, most of the deviation of the air-fuel ratio from the target value at the time of acceleration / deceleration of the engine is caused by a quantitative change of the adhering fuel and the stray fuel adhering to the intake manifold or the intake port of the intake system. Therefore, the amount of the adhering and floating fuel greatly changes according to the operating state of the engine. In addition, the amount of adhering and floating fuel does not change stepwise with respect to the change in the operating state, but changes with a certain delay, and the time constant of this delay is not constant. Further, the change in the amount of the adhering and floating fuels depends not only on the change in the operating state, but also on the amount at that time depending on the magnitude of the difference from the amount in the equilibrium state (steady state).

Against this background, a conventional fuel supply control device for an internal combustion engine is disclosed, for example, in JP-A-61-96148. In this device, the required load per unit rotation of the engine is obtained from the output of an air flow meter provided upstream of the throttle valve, and the fuel injection amount is calculated from this. Also,
After starting, the steady-state air-fuel ratio is enriched by increasing the amount of fuel after starting or increasing the amount of warm-up, thereby preventing breathing and stalling.

(Problems to be Solved by the Invention) However, in such a conventional fuel supply control device for an internal combustion engine, the fuel increase correction after the start is performed by enriching the steady-state air-fuel ratio by the post-start increase Kas or the warm-up increase Ktw. However, since the intake port temperature and intake valve temperature are low immediately after starting, and the wall flow in the intake pipe is large, breathing during acceleration is likely to occur in the above configuration, and deceleration occurs. The displacement of CO and HC at the time is large, and the fuel efficiency is poor,
There was a problem that the spark plug was easy to smolder.

That is, as shown in the timing chart of FIG. 8, after the engine is started, the above-mentioned increase Kas or the like after the start is simply reduced, so that the throttle valve opening TVO is changed before Kas = 0. When acceleration and deceleration are performed, a considerable part of the injection amount Ti is often transiently taken up in the wall flow in the intake pipe, so that the air-fuel ratio lean spike during acceleration or Causing a rich spike during deceleration,
In the end, it caused breathing and smoldering of the spark plug.

(Object of the Invention) Therefore, the present invention uses a transient correction amount that takes into account the wall flow even after the start, and further corrects this in accordance with the warm-up state after the start, so that breathing immediately after the start It aims to prevent exhaust emissions and improve exhaust characteristics and fuel efficiency.

(Means for Solving the Problems) In order to achieve the above object, a fuel supply control device for an internal combustion engine according to the present invention, as shown in FIG. a, a basic supply amount calculating means b for calculating a basic supply amount of fuel based on the detected operating state, a start detecting means c for detecting the start of the engine, and when the engine starts, the detected cooling water temperature A water temperature correction value calculating means d for calculating a water temperature correction value obtained by subtracting a water temperature correction initial value set in accordance with the detected cooling water temperature by a reduction rate set in accordance with the detected cooling water temperature; and A pseudo cooling water temperature setting means e for setting a pseudo cooling water temperature by subtracting a correction value, and calculating a transient correction amount for correcting a wall flow of fuel based on the detected cooling water temperature. Transient calculating means f for calculating the transient correction amount based on the pseudo cooling water temperature
And correcting the basic supply amount according to the transient correction amount,
A supply amount calculating means g for determining a final supply amount and a fuel supply means h for supplying fuel to the engine based on the output of the supply amount calculating means are provided.

(Operation) In the present invention, a transient correction amount that takes wall flow into account immediately after the start of the engine is calculated.

Therefore, even if acceleration or deceleration occurs immediately after the start, the response delay due to the adhering fuel is corrected so that the fuel injection amount becomes appropriate, breathing is prevented, engine stall is prevented, and exhaust characteristics and fuel efficiency are improved.

Hereinafter, the present invention will be described with reference to the drawings.

2 to 7 are diagrams showing an embodiment of a fuel supply control device for an internal combustion engine according to the present invention. First, the configuration will be described.
FIG. 2 is a diagram showing the overall configuration of the present apparatus. In FIG. 2, reference numeral 1 denotes an engine, intake air passes from an air cleaner 2 through an intake pipe 3, and fuel is injected from an injector (fuel supply means) 4 based on an injection signal Si. And
Exhaust gas combusted in the cylinder is introduced into a catalytic converter 6 through an exhaust pipe 5, and in the catalytic converter 6, harmful components (CO, HC, NOX) in the exhaust gas are purified by a three-way catalyst and discharged.

The flow rate Qa of the intake air is detected by a hot wire type air flow meter 7 and controlled by a throttle valve 8 in the intake pipe 3. In addition, as a type of the air flow meter 7,
It may be of a hot film type, that is, it may be of any type as long as it measures the flow rate of intake air. Therefore, a flap type sensor may be used, but the negative pressure sensor is excluded.

The opening TVO of the throttle valve 8 is detected by a throttle valve opening sensor 9, and the rotation speed N of the engine 1 is detected by a crank angle sensor 10. The temperature Tw of the cooling water flowing through the water jacket is detected by a water temperature sensor 11, and the oxygen concentration in the exhaust gas is detected by an oxygen sensor 12. As the oxygen sensor 12, a sensor having a characteristic that its output Vs changes suddenly at a stoichiometric air-fuel ratio is used. Further, the start of the engine 1 is detected by an ignition switch (start detecting means) 13.

The air flow meter 7, the throttle valve opening sensor 9, the crank angle sensor 10, the water temperature sensor 11 and the oxygen sensor 12 constitute an operating state detecting means 14, and the output from the operating state detecting means 14 and the ignition switch 13 is Input to the control unit 20. The control unit 20 has functions as a basic supply amount calculating means, a water temperature correction value calculating means, a pseudo cooling water temperature setting means, a transient calculating means and a supply amount calculating means, and comprises a CPU 21, a ROM 22, a RAM 23 and an I / O port 24. Is done. The CPU 21 fetches external data required by the I / O port 24 according to the program written in the ROM 22, and transmits and receives data to and from the RAM 23 while processing values required for the injection amount control. Performs arithmetic processing and processes the processed data as necessary.
Output to The signals from the sensor groups 13 and 14 are input to the I / O port 24, and the injection signal S is output from the I / O port 24.
i is output. The ROM 22 stores a calculation program for the CPU 21, and the RAM 23 stores data used for calculation in the form of a map or the like.

 Next, the operation will be described.

FIG. 3 is a flowchart showing a program for calculating the transient correction amount Kathos.
Executed once every time.

First, Lee Keun Deployment switch 13 it is determined whether or not on by P _1, when it is turned on is determined to be after the start,
Further determines whether the restart with P _2. When Lee Keun Deployment switch 13 is not turned on jumps to P _6. P is ₂ when the restart is determined whether or not turned the engine 1 or 1 minute P _3, jumps to P ₆ rather than immediately after starting when turning over 1 minute. Therefore, the steps P ₄ and P ₅ are executed only within one minute after the first start or restart.

P ₄ in the initial value of the fourth temperature corrected partial from a table map shown in FIG Dtw based on this cooling water temperature Tw to look up. This initial value becomes higher as the cooling water temperature Tw becomes lower,
In the following, it is set to be smaller on the contrary. This is because the relationship between the cooling water temperature Tw and the wall flow is considered.

Then, to look up the attenuation ΔDtw from a table map shown in FIG. 5 based on the cooling water temperature Tw at P _5. The attenuation amount ΔDtw is set to a larger value as the cooling water temperature Tw is lower. Here, the water temperature correction amount Dtw decreases sequentially in synchronization with the rotation, and this is shown in the subroutine of FIG. In Figure 6, it calculates the current temperature corrected partial Dtw according to the following equation at P _11.

Dtw = Dtw'-ΔDtw ...... However, Dtw '; previous value is then determined whether Dtw at P ₁₂ is negative, Dtw <
When 0 and Dtw = 0 at P _13, is terminated without the routine at this time when the Dtw ≧ 0.

Returning to Figure 3 program again calculates the pseudo coolant temperature Tws in accordance with the following equation by P _6.

Tws = Tw-Dtw ...... Then, transient correction amount in accordance with the pseudo coolant temperature Tws at P ₇ Kat
Calculate hos.

Using the transient correction amount Kathos calculated in this way, the final injection amount is calculated by a routine (not shown) according to the following equation.

Ti = (Tp + Kathos) × Tfbya × (α + αm) + Ts where Tp is the basic injection amount {Tp (Qa / N) × K}, Tfbya
Is the target fuel-air ratio and is given by the following equation.

Tfbya = Mfbya + Ktw + Kas + Kh where Ktw; warm-up increase K; increase after start Kh; high water temperature increase In the formula, Mfbya is a target air-fuel ratio, and Mfbya is a rotation speed N.
And α-N flow rate Qho (air amount given by throttle valve opening TVO and rotational speed N) are given by looking up from a table map assigned as parameters.

Α is a λ control correction coefficient of the air-fuel ratio based on the output of the oxygen sensor 12, and αm is a mixture ratio learning control correction coefficient. Ts is the invalid pulse width.

A timing chart of the operation when the above-described program is executed is shown in FIG.

In FIG. 7, when acceleration and deceleration are performed immediately after the start as in the prior art, first, a water temperature correction amount Dtw is set at the same time as the start, and thereafter, gradually becomes smaller in rotation synchronization. The injection amount Ti fluctuates during acceleration and deceleration, but during acceleration, the transient correction amount Kathos includes an increase in Dtw as shown in the figure in addition to the steady amount during acceleration.

In this case, the increased amount of Dtw shows a tendency to largely decrease immediately after the start immediately after the start, in consideration of the existence of the wall flow. Therefore, at the time of acceleration, an appropriate fuel increase is secured, and the lean spike in the air-fuel ratio is reduced. As a result, breathing and stalling during starting are prevented. This includes prevention of breathing and engine stall caused by shocks such as power steering load.

On the other hand, even during deceleration, the amount of Dtw reduction taking into account the wall flow exists, so the rich spike in the air-fuel ratio is reduced, and CO,
The HC displacement is reduced, the smoldering of the spark plug is also prevented, and the steady increase is reduced to improve fuel economy.

(Effect) According to the present invention, when the engine is started, the pseudo cooling water set by subtracting the water temperature correction value calculated by the water temperature correction value calculating means from the detected cooling water temperature by the pseudo cooling water temperature setting means. Since the transient correction amount for correcting the wall flow of the fuel is calculated based on the water temperature, it is possible to optimize the injection amount by correcting the response delay due to the adhered fuel at the time of acceleration or deceleration immediately after the start, and In addition, it is possible to prevent engine stall and improve exhaust characteristics and fuel efficiency.

[Brief description of the drawings]

FIG. 1 is a basic conceptual diagram of the present invention, FIGS. 2 to 7 are diagrams showing an embodiment of a fuel supply control device for an internal combustion engine according to the present invention, FIG. 2 is an overall configuration diagram thereof, and FIG. Is a flowchart showing a program for calculating the transient correction amount, and FIG.
FIG. 5 is a diagram showing a map of Dtw, FIG. 6 is a flowchart showing a subroutine for calculating Dtw, FIG. 7 is a timing chart for explaining the operation, FIG. 5 is a timing chart for explaining the operation of a conventional fuel supply control device for an internal combustion engine. 1 ... engine 4 ... injector (fuel supply means) 13 ... ignition switch (start detection means) 14 ... operation state detection means 20 ... control unit (basic supply amount calculation means, water temperature correction value Calculation means, pseudo cooling water temperature setting means, transient calculation means, supply amount calculation means).

Claims (1)

(57) [Claims] A) operating state detecting means for detecting an operating state of the engine; b) basic supply amount calculating means for calculating a basic supply amount of fuel based on the detected operating state; c) starting of the engine And d) when the engine is started, a water temperature obtained by subtracting an initial value of a water temperature correction amount set according to the detected cooling water temperature by a reduction rate set according to the detected cooling water temperature. Water temperature correction value calculating means for calculating a correction value; e) pseudo cooling water temperature setting means for setting the pseudo cooling water temperature by subtracting the water temperature correction value from the detected cooling water temperature; f) based on the detected cooling water temperature Transient calculation means for calculating the transient correction amount for correcting the fuel wall flow, and for calculating the transient correction amount based on the pseudo cooling water temperature when the engine is started; correction And corrected in accordance with the,
A fuel supply control device for an internal combustion engine, comprising: supply amount calculation means for determining a final supply amount; and h) fuel supply means for supplying fuel to the engine based on an output of the supply amount calculation means.