JPH0249942A - Fuel supply control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent drop of the engine revolving speed in an arrangement where the fuel amount is incrementally corrected for a certain period of time after the engine is started, by increasing the suction air amount when actuation of external load is sensed, and further correcting incrementally the fuel to be increased after starting. CONSTITUTION:While engine 1 is in operation, an ECU 9 judges the engine operating condition according to different parametric signals about the engine, and the fuel injection time is calculated according to the result from judgement, and this value is incrementally corrected according to the post-start increment factor determined according to the coolant temp. about the specified period after starting of the engine. The operating condition of external load, for ex. airconditioner, is sensed from the output of an airconditioner switch 17, and when the airconditioner is put on, an aux. air amount control valve 6 is controlled so as to increase the suction air amount. Further during this time of airconditioner being on, the increment factor shall be a one multiplied with a certain increment corrective factor to serve for further incremental correction of the fuel injection time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel fJli supply control device for an internal combustion engine, and in particular, to a device for appropriately controlling the amount of fuel supplied after starting the engine according to the operating state of an external load. The present invention relates to a control device.

(Prior Art) Conventionally, in order to prevent engine stall after engine startup and smooth transition to acceleration immediately after engine startup, after the internal combustion engine has started, the amount of fuel supplied to the engine has been adjusted according to the engine temperature. There is a known fuel supply control method after starting an internal combustion engine, in which an initial increase value is set and the initial increase value is gradually decreased by a predetermined degree of decrease (for example, Japanese Patent Laid-Open No. 60-2371
31 and JP-A No. 61-28730).

(Problems to be Solved by the Invention) However, the above-mentioned conventional technology causes problems such as a low engine speed when the intake air amount of the engine is controlled to increase according to the operation of an external load after starting. There was a problem.

In other words, the reason why the amount of fuel is increased after starting in the above conventional technology is that immediately after starting, the temperature of the intake pipe wall is lower than the temperature inside the combustion chamber, so the amount of fuel adhering to the intake pipe wall is large, and the fuel amount is increased. Since the degree of atomization is low, this is to compensate for the substantially leaner supply air-fuel ratio that accompanies this, and to obtain good combustion.

First, when an external load on the engine is activated, such as a near conditioner, the amount of air intake into the engine is increased to prevent the engine speed from decreasing due to the increased load on the engine. When such control is performed after the engine has started,
As the amount of intake air increases, the absolute pressure inside the intake pipe increases by 1.0 mm, so that the atomization characteristics of the fuel deteriorate.

However, the above-mentioned conventional technology does not take into account the deterioration of atomization characteristics due to such causes, so it cannot deal with this problem, and the engine speed decreases due to the supplied air-fuel ratio becoming lean transiently. If the degree of this is high, engine stall will result.

The present invention has been made in order to solve the problems of the prior art described in ``-'', and is aimed at reducing the engine speed due to the increase in the amount of intake air when the external R++ load is activated after starting. It is an object of the present invention to provide a fuel supply control device for an internal combustion engine that can reliably prevent engine stall caused by l = - and thereby provide good starting characteristics.

(Means for Solving the Problem) In order to achieve the second object, the present invention supplies an increased amount of fuel by an increase value to the internal combustion engine for a predetermined period after starting the internal combustion engine or for a predetermined number of engine revolutions. In a fuel supply control device for an internal combustion engine, the load detection means detects the operating state of an external load, and the intake air amount increasing means increases the intake air amount of the engine when the load detection means detects the operation of the external load. and an increase correction means for increasing the increase value when the load detection means detects operation of an external load.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram schematically showing the entire fuel supply control device for an internal combustion engine according to an embodiment of the present invention. Reference numeral 1 indicates, for example, a four-cylinder internal combustion engine, and the engine 1 has an open end. Intake pipe 3 and exhaust pipe 4 with air cleaner 2 attached
is connected. A throttle valve 5 is installed in the middle of the intake pipe 3.
An air passage 8 is provided downstream of the throttle valve 5 and is open to the intake pipe 3 and communicates with the atmosphere. An air cleaner 7 is installed at the atmospheric side 11 end of the air passage 8, and an auxiliary air amount control valve 6 is disposed in the middle of the air passage 8. This auxiliary air amount control valve (hereinafter simply referred to as "control valve") 6 is a normally closed solenoid valve, and includes, for example, a near solenoid 6a and a valve 6b that opens the air passage 8 when the solenoid 6a is energized. It is configured. The solenoid 6a is an electronic control unit (hereinafter F r
ECUJ) 9, and the EC
By controlling the amount of current supplied by U9, the opening degree of the control valve 6, that is, the amount of intake air is continuously controlled.

A fuel injection valve IO is provided between the engine l of the intake pipe 3 and the opening 8a of the air passage 8, and this fuel injection valve 10 is connected to a fuel pump (not shown) and electrically connected to the ECU 9. It is connected.

The throttle valve 5 has a throttle valve opening (0 + 1).
Sensor 1. l is n of the intake pipe 3; 1. An intake pipe absolute pressure (PB^) sensor 13 communicating with the intake pipe 3 via a pipe 12 is located downstream of the opening 8a of the air passage 8. An intake air temperature (T^) sensor 14 for detecting intake air temperature is attached to the intake pipe 3 downstream of the air intake pipe 13, and an engine coolant temperature (Tw) sensor 15 and an engine rotation speed (Ne) sensor 16 are attached to the engine 1 body. and each sensor is electrically connected to the ECU 9.

The Ne sensor 16 outputs a crank angle position signal at a predetermined crank angle position at a 180° rotation f5 of the crankshaft of the engine I, that is, at a crank angle position before the top dead center (TDC) at the start of the intake stroke of each cylinder. A pulse (hereinafter referred to as I "DC signal pulse") is output to EC:U9.

The ECU 9 also includes a near conditioner (not shown).
An air conditioner (I (AC) switch 17 and a starter switch 18 of the engine 1 as load detection means for detecting the operating state of an external load) are electrically connected and a detection signal thereof is supplied.

EC, U9 shapes the input signal waveforms from various sensors, corrects the voltage level to a predetermined level, and converts the analog signal (1
An input circuit 9a having functions such as converting α into a digital signal value, and a central processing circuit (hereinafter referred to as rCPUJ) 9
b, storage means 9C for storing various calculation programs executed by the CPU 9b, calculation results, etc., an output circuit 9d for supplying drive signals to the control button t6 and the fuel injection valve 10, respectively.

That is, in this embodiment, the ECU constitutes the intake air amount increasing means and the increase correction f stage.

The CPU 9b determines the operating state of the engine l according to the various engine parameter signals described above, and also determines the 'I''D C18 according to the determined operating state of the engine l.
Calculate the current It to be supplied to the near solenoid 6a of the control valve 6 in synchronization with the signal pulse.In particular, when the air conditioner switch 17 is on, that is, when the near conditioner is operating, the current fit is increased. This increases the amount of intake air.

Further, the CPU 9b determines the fuel injection time period for which the fuel injection valve 10 should be opened in synchronization with the 'I' DC signal pulse according to the determined operating state of the engine l, using the following formula (
Calculate based on 1).

Tou Ding = 1'iX KASTX Kl + K2-
(1) Here, 'ri represents the basic fuel injection time of the fuel injection valve 6, and is determined depending on, for example, the intake pipe absolute pressure P++^ and the engine rotation speed Ne.

KAST is a post-start increase coefficient (hereinafter simply referred to as "increase coefficient 1") as an increase value, which is calculated according to a subroutine (FIG. 2) described later according to the present invention.

K1 and K2 are other correction coefficients and correction variables that are respectively calculated according to various engine parameter signals, and are designed to optimize engine characteristics such as fuel efficiency and acceleration characteristics according to the operating state of the engine. set to the desired value.

The CPU 9b sends a drive signal for opening the control valve 6 and the fuel injection valve 10 to the control valve 6 and the fuel injection valve 10 through the output circuit 9d based on the current amount (2) and the fuel injection time 1" OUT obtained as described above. rlO respectively.

FIG. 3 shows a flowchart of a subroutine for calculating the n(J increase m coefficient KAST). This program is executed in synchronization with the generation of the 'I' ID C signal pulse after the engine l has finished starting. .

First, in step 201, it is determined whether the engine 1 was in the starting mode during the previous loop. This starting mode refers to an operating state of the engine 1 in which, for example, the engine rotational speed Ne is lower than the cranking rotational speed Ncg (for example, 40 rpm) and the starter switch 18 is in an on state. This answer is 11 constant (Yes), that is, the current loop is the maximum υJ after engine 1 leaves the starting mode.
l' 1. ) C (When applicable when the * pulse is generated, the increase coefficient K is calculated according to the engine coolant temperature ゛1゛W from the KAST table stored in the nIJ storage means 9c.
Read the initial 61'l of AST.

This engine cooling water temperature Tw is the final 'I゛1 in the starting mode.
) is determined upon the occurrence of the C signal pulse.

FIG. 3 is a diagram showing an example of this KAST table.

As is clear from the figure, in the KART table, the engine cooling water temperature is 1' w G, and the four reference values 'WASO ~ T WAS3 (1' WASO
ASI <TWAS2 (i″WAS3) is set, and the initial value of the increase coefficient KAST is the engine cooling water temperature
“w is below the above reference value TWASO, TWAsl, Tw
For As2 and °I' WAS 3 or more, K
Set to ASTO-KAST3, standard 1fi-1'w
'I' WASI between Asa and 'I' WAS 3
and I'w values other than r'wAs2 are determined by interpolation calculation.

Note that this KAsT table can be set in various ways depending on engine characteristics and the like.

0: If the answer to step 201 is negative (No), that is, if the current loop is the second or subsequent loop after the engine l leaves the starting mode, the current increase coefficient KAS
T is set to the value obtained by subtracting the subtraction constant value ΔKAS from the value at the previous loop (step 203). This subtraction constant value ΔKAST represents the degree of decrease of the increase coefficient KAST after starting, and is calculated according to the subroutine shown in FIG. 4.

First, in step 401, it is determined whether the increase coefficient KAST is larger than a first determination 11KAsrgo (for example, 1.3), which is a fixed value. This first discriminant value KAST
! Reference numeral 40 is provided to maintain the increase period after starting for a certain length of time even when the initial value of the increase coefficient KAST is small, that is, when the engine temperature at the time of startup is high. Is the answer to step 401 I? Yes, that is, K
AST> When KAsrRo holds true, the increase coefficient KAST is the second determination 1aKAsTl! It is determined whether the value is greater than 1 (step 402). This second discriminant value KASTI! l is calculated according to the following equation (2).

KASTO1!1= (KAsTO-1,0) Xf
lAsn+1.0...(2) Here, KASTO was calculated in step 202 of FIG. This is the initial value of the increase coefficient KAST. Also, R.A.S.
TI is a first predetermined coefficient that is set together with a second predetermined coefficient RAST2, which will be described later, according to the subroutine shown in FIG. That is, in the four steps 501, the intake temperature 'l'^INT determined at the time of generation of the final 1' I) C signal pulse of the starting mode becomes the first predetermined temperature '1'^^s.
r (for example, 0° C.) and the second predetermined temperature TA
It is determined whether the temperature is lower than KTW (>TAAST, for example, 20° C.). This determination is to determine whether or not the fuel is being used under conditions where its atomization characteristics are low. If this answer is negative (No), that is, r A I NT≦'I'AAS
When T or TArNT≧TAKTW holds, f
First and twelfth predetermined coefficients RAS 1. R.A.S.
T2 is the second 11α RASTI-8 for normal use.
, RAsr2-8 (for example, 0.7.0.4, respectively) (step 502), and when TW is satisfied (Yes), i.e., 1'AAST<"I"AINT<'1°^, Assuming that the atomization characteristics of the fuel i21 are low, the RASTI and l)^ST2 values are as follows:
1 to 2nd 11 RASr+-s, RAST2-I+
The first values RASTI−^, RAS are each greater than
T2-^ (for example, 0.8.0.5, respectively) is set (step 503), and this routine ends.

Returning to FIG. 4, the answer to step 402 is affirmative (Yes).
), that is, when KAST>KASTRI holds, the subtraction constant value ΔKAST is set to the first predetermined value ΔKAST.
Step 103) to end this routine. On the other hand, the answer to step 401 or 402 of n; I is negative (No), that is, KAST≦KASTI! O or KA
When ST≦KAsTRI holds true, the increase coefficient KA
It is determined whether ST is larger than a third determination value KAsrg2, which is smaller than the second determination value KASTRI (step 404). This third discrimination (1αKASTR2 is
The above-mentioned second predetermined coefficient R set in the initial 11KAsyo of the increase coefficient KAST and the subroutine of FIG.
It is calculated according to the following equation (3) by applying AST2.

KASTI! 2: (KAsro-1,0)XR
^sd2+1.0...(3) The answer to step 404 is affirmative (Yes), that is, KAS
T> When KASTR2 holds true, the 0:1 subtraction constant value ΔKAST is set to the nii first predetermined value ΔKASTI.
While setting a smaller second predetermined value (1i!ΔKAsT2 (step 405), negative (No), i.e. 1 (A
ST≦KASTI! 2 holds, the above AKAS
The T value is set to a third predetermined value ΔKAST3 which is smaller than the second predetermined value ΔKAST2 (step 4).
06), this routine ends.

Returning to FIG. 2, in step 204 following step 202 or 203, it is determined whether the increase coefficient KAST calculated in these steps is greater than 1.0.

If the answer is 11 (Yes), the air conditioner (1r
ΔC) It is determined whether the switch 17 is in the on state or not (step 205). If the answer is negative (No), that is, the near conditioner is not operating, then the increase coefficient is this time lII! KAsTτ1 is set to the KAST value calculated in step 202 or 203 (step 2
06).

On the other hand, if the answer to step 205 is affirmative (Yes), that is, the near conditioner is operating, the current value KAstn of the increase coefficient is set to step 202 or 203.
The KAST value calculated in step 207 is reset to a value obtained by multiplying the predetermined increase correction coefficient Kn^C (for example, 1.1) for when the near conditioner is activated, and the program is terminated.

While the near conditioner is in operation, the intake air amount is increased by increasing the amount of current I supplied to the control valve 6 as described in 01, and the increase coefficient KAST is increased by executing step 207 described above. The increase is compensated for by applying the correction coefficient Kn^C. therefore,
At this time, as the amount of intake air increases, the absolute pressure Pn^ in the intake pipe increases, and even if the atomization characteristics of the fuel decrease,
Since the amount of fuel is increased to compensate for this,
The supplied air-fuel ratio does not become lean transiently, and therefore, low engine speed and engine stall caused by this can be reliably prevented and good starting characteristics can be obtained.

If the answer to step 204 is negative (No), that is, KAST
When ≦1.0 holds true, the K AST (iI
4 to f+ff + and reset to 0 (step 20
8) Exit this program.

As a result of calculating the increase coefficient KAST as described above, the increase coefficient KAST decreases along the center line shown by the solid line or the broken line in FIG. That is, the solid line i in the same figure
(I and first and second predetermined coefficients RASTI.

As RAST2, the second value RASTI-B, RAS
When T2-[1 is applied, the dashed line ■1 is set to the same initial value KASTO, and the first value RASTI-^, RA is set as the RASTI and RAST2 values.
When ST2-^ is applied, the solid line ■ is the initial value KA
It shows the transition of the staff increase coefficient KAsT when STO is smaller than the first discrimination value KAsTRO.

In addition, in this embodiment, the increase coefficient KAST is set to 'D
Although an example has been shown in which the amount of fuel is decreased every time the c signal pulse occurs, that is, the amount of fuel is increased over a predetermined number of engine rotations after starting, the present invention is not limited to this. Alternatively, the amount of fuel may be increased over a predetermined period after startup.

(Effects of the Invention) As detailed above, according to the present invention, when the external load is operating after the internal combustion engine starts, the amount of intake air is increased, and the amount of fuel is increased after the engine starts. is further increased and corrected, so the supplied air-fuel ratio does not become transiently lean at this time, and therefore, a drop in engine speed and engine stall caused by this are reliably prevented and good starting characteristics are obtained. It has the following effects:

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with reference numeral 1121 being an overall configuration diagram of a fuel supply control device, FIG. 2 being a flowchart of a subroutine for calculating the post-start increase coefficient KAsT according to the present invention, and FIG. FIG. 4 is a flowchart of a subroutine for setting the subtraction constant value ΔKAsT;
FIG. 5 is a flowchart of a subroutine for setting a predetermined coefficient applied to set a judgment value for switching the subtraction constant value ΔKAST, and FIG.
6 which is a diagram showing the change mode of means), 17... Air conditioner (IIAC) switch (load detection means), KAsT... Post-start increase coefficient (increase value).

Claims (1)

[Claims] 1. A load that detects the operating state of an external load in a fuel supply control device for an internal combustion engine that supplies the engine with an increased amount of fuel based on an increase value for a predetermined period of time after the internal combustion engine starts or for a predetermined number of engine rotations. a detection means;
intake air amount increasing means for increasing the intake air amount of the engine when the load detecting means detects the operation of an external load; and increasing the increase value when the load detecting means detects the operation of the external load. 1. A fuel supply control device for an internal combustion engine, comprising a fuel increase correction means.