JPH0249943A - Internal combustion engine fuel supply control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel supply control device for an internal combustion engine, and in particular, it controls the amount of fuel supplied after starting the engine in an appropriate manner according to the atomization characteristics of the fuel used. The present invention relates to a control device for controlling.

(Prior Art) Conventionally, in order to prevent engine stall after starting the engine and to accelerate the acceleration immediately after starting the engine,
After starting the internal combustion engine, an initial increase value for the amount of fuel supplied to the engine is set according to the engine temperature, and the initial increase m
A fuel supply control method after starting an internal combustion engine is known in which the value is gradually decreased by a predetermined degree (for example, Japanese Patent Laid-Open No. 60-2
37131 and JP-A-61-28730)
.

(Problems to be Solved by the Invention) However, the above-mentioned conventional technology has problems such as a decrease in engine speed after starting when fuel with low atomization characteristics is used.

In other words, the reason why the amount of fuel is increased after starting in the conventional technology described above is because the temperature of the intake pipe wall is lower than the temperature inside the combustion chamber immediately after starting, and therefore, the amount of fuel that lands on the intake pipe wall is large. , since the degree of atomization of the fuel t1 is low, this is to compensate for the substantially leaner supply air-fuel ratio accompanying this and obtain good combustion.

On the other hand, for the purpose of preventing air pollution caused by vaporized fuel being released into the atmosphere, fuel with low atomization characteristics (hereinafter referred to as low atomization fuel may be done. When the low atomization fuel is used, the amount of fuel adhering to the intake pipe wall increases because the atomization characteristics are lower than that of normal fuel after the engine is started when the intake pipe wall temperature is low.

However, the conventional technology described above does not take into account the increase in the amount of adhering fuel due to such causes, and is therefore unable to deal with this problem. When the number decreases and the degree of decrease is high, it will lead to engine stall.

The present invention has been made in order to solve the problems of the prior art described in section 2, and when low atomization fuel is used in the warm season, the engine after starting depending on the atomization characteristics of the fuel. It is an object of the present invention to provide a fuel supply control device for an internal combustion engine that can appropriately prevent a decrease in rotational speed and an engine stall caused by this, and thereby can obtain good starting characteristics.

(Means for Solving the Fi Problem) In order to achieve the above object, the present invention provides an increase -1111'! that gradually decreases after starting an internal combustion engine over a predetermined period of time after the start or a predetermined number of engine revolutions. A fuel supply control device for an internal combustion engine that supplies an increased amount of fuel to the engine includes an atmospheric temperature detector that detects atmospheric temperature; and an increase correction means for increasing the increase value.

Further, in the above configuration, the 01j increase-1it correction means is set to 11 when the atmospheric temperature is 1 unit higher than the predetermined value. When the value is less than the second predetermined value, the value is incremented by 1 at the time of 01i.

Furthermore, in the second groove formation, instead of the increasing r1hn positive means, when the atmospheric temperature detected by the atmospheric temperature detector is equal to or more than a predetermined 1/(, the predetermined period is extended or 01
(j) increasing period extension means for increasing the predetermined number of engine rotations;

(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 entirety of a 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 and an open end. Intake pipe 3 and exhaust W with air cleaner 2 attached to
4 are connected. A throttle valve 5 is disposed in the middle of the intake air W3, and an air passage 8 that opens into the intake pipe 3 and communicates with the atmosphere is disposed downstream of the throttle valve 5. An air cleaner 7 is provided at the end 1-1 of the air passage 8 that is open to the atmosphere, and an auxiliary air amount control valve r6 is disposed in the middle of the air passage 8.This auxiliary air amount control valve (hereinafter referred to as The control valve 6 (referred to as control valve J) is a normally closed electromagnetic valve, and is composed of, for example, a near solenoid 6a and a valve 6b that opens an air passage 8 when the solenoid 6a is energized. 6a is electrically connected to the electronic control unit 1 (hereinafter referred to as rEcUJ) 9, and by controlling the amount of current supplied by the ECU 9, the opening degree of the control valve 6, that is, the intake air amount, is continuously controlled. controlled.

A fuel injection valve 1O is provided between the engine 1 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.

A throttle valve opening (On+) sensor 11 is installed in the throttle valve 5 to detect the opening [1
On the downstream side of 8a, an intake pipe absolute pressure (1)B^)sen-)J-13 communicating with the intake pipe 3 via a pipe 12 is connected to the intake pipe 3 on the F flow side from the intake pipe absolute pressure sensor 13. is the intake air temperature ('I゛^
) sensor 14, an engine cooling water temperature ('['w) sensor' 15 and an engine rotation speed (N
e) Sensors 16 are mounted on each sensor, and each sensor is electrically connected to EC and U9.

Ne sensor! 6 is a predetermined crank angle position every 180° rotation of the crank of the engine 1, that is, a crank angle position before the predetermined crank angle with respect to the top dead center ('l'1) C) at the start of the intake stroke of each cylinder. A crank angle position signal pulse (hereinafter referred to as VrDC4R pulse J) is output to the ECU 9.

The ECU 9 also includes an air conditioner (11ΔC) switch 17 that detects the operating state of a near conditioner (not shown).
and the starter switch 18 of the engine I are electrically connected and the detection signal thereof is supplied.

c' and cu9 are input circuits 9 having functions such as shaping input signal waveforms from various sensors, correcting voltage levels to predetermined levels, and converting analog signal values into digital signal values.
a, central processing circuit (hereinafter referred to as rcPUJ) 9b,
It is comprised of a storage means 9c for storing various calculation programs and calculation results executed by the CPU 9b, and an output circuit 9d for supplying drive signals to the control valve 6 and fuel injection valve IO, respectively.

That is, in this embodiment, the ECU 9 constitutes an increase compensation r1 means and an increase period extension means.

The CPU 9b determines the operating state of the engine 1 according to the various engine parameter signals described above, and also controls the linear solenoid 6a of the control valve 6 in synchronization with the 1' DC signal pulse according to the determined operating state of the engine 1. niO
(Calculates the amount of current I to be supplied.) In addition, the CPU 9b calculates the amount of current I to be supplied.
) The fuel injection time 'rouT during which the fuel injection valve 10 should not be opened in synchronization with the C signal pulse is calculated based on the following equation (1).

1'our=i'i
I) Here, '1゛i is the basic twist t' of the fuel injector 6)
This indicates the injection time and is determined depending on, for example, the intake pipe absolute pressure I'B^ and the engine rotation speed Ne.

KAsTI also performs a subroutine (second
The increase Q'c (1') is the increase coefficient after startup (hereinafter referred to as the "increase coefficient") calculated according to the figure.

K1 and K2 are the coefficients and correction variables calculated according to various engine parameter signals, respectively, and are used to optimize various characteristics such as fuel efficiency and acceleration characteristics according to the operating state of the engine. It is set to the required value as specified.

CPIJ9 b is the amount of current found in a series of steps! Output circuit 9 (
1 to the control valve 6 and the fuel injection valve 10, respectively.
'To provide.

FIG. 3 shows a flowchart of the belt nub routine for calculating the O1I increase coefficient KAST. This program is executed in synchronization with the generation of the C signal pulse after the engine 1 has finished starting.

First, in step 201, it is determined whether engine I 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 speed Ne is lower than the cranking speed Ncg (for example, 400 rpm I++) and the starter switch 18 is in the on state. If the answer is 11 (Yes), that is, this time the loop corresponds to the first I'' DC signal pulse after engine l leaves the starting mode, then 61
The initial value of the increase coefficient I (^ST) is read out from the KAST table stored in the storage means 9c in accordance with the engine cooling water temperature "1"W.

This engine cooling water temperature Tw is the final TI in starting mode)
c (Determined when the * pulse is generated.

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

As is clear from the figure, in the ST table, there are four criteria (f
1T'wAso~TwAs3(TwAso(1''wAs
I (TWAS 2 < TWAS 3) is set,
The initial value of the increase coefficient KAsT is the engine coolant temperature 'I''
W is ``2-key group Q'! In 'rWA SO below, T
The smaller the Tw snake for wAsl, i'WAS2 and ``I'WAS3, the larger the ftc (how, respectively, KAsro ~ 1 (set to AST3, base 1'! ((mouth'WASO and Between TWAS3 and I
For '1゛w values other than ``WAS+'' and ``GOWAS 2,'' it is determined by interpolation weighting.

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

If the answer to step 201 is negative (No), that is, if the current loop is the second or later loop after the engine 1 leaves the starting mode, the current increase coefficient KAST is set to 1; (Constant value ΔKAST subtracted from 1α
(step 203). This subtraction constant value ΔKAS represents the degree of decrease after the start of the increase coefficient KAST, and is calculated according to the subroutine shown in FIG.

First, in step 401, it is determined whether the increase coefficient KAST is larger than a first determination value KASTRO (for example, 1.3), which is a fixed value. This first discrimination value KASTI!
0 is provided in order to maintain the fuel increase period after startup for a certain length of time even when the initial value of the fuel increase coefficient KAST is small, that is, when the engine temperature at startup is high. The answer to step 101 above is the front leg (Yes), i.e.
When ST>KASTRO holds true, the increase coefficient KA
It is determined whether ST is larger than the second determination value KAsr*+ (step 402). This second discrimination value KA8T
R1 is calculated according to the following equation (2).

KASTR1= (KASTO-1,0) XRAST
I4-1.0 Here, RASTO is step 2 in Figure 2.
This is the initial value of the increase coefficient KAST calculated in 02.

Further, RASTI is a first predetermined coefficient that is set according to a subroutine shown in FIG. 5, which will be described later.

The answer to step 402 is IV definite (Yes), that is, KA
When ST>KASTRI holds true, the subtraction constant value ΔKAST is set to the first predetermined value ΔKASTI (step 403), and this routine ends. On the other hand, if the answer to step 401 or 402 is negative (No), that is, K
ASτ≦KAsrt:o or KAsyS KAsy*+
holds, the fffffi coefficient KAST is a third discriminant value KA that is smaller than the second discriminant value KASTR1.
Determine whether it is larger than STk2 (step 404
). This third discrimination value KASTR2 is calculated according to the following equation (3).

KAsrg2= (KASTO-1,0) XI?
^sr2+1.0... (3) Here, RAS2 is the second predetermined coefficient, and according to the subroutine of FIG. 5, which will be described later, 1l (J is set to

The answer to step 404 is the front leg (Yes), that is, KAS.
When T>KASTR2 holds true, the subtraction constant value ΔKAST is set to a second predetermined 1-direction ΔKAST2 that is smaller than the first predetermined value ΔKASTI (step 405), while negative (No), that is, KAST≦KAST
When R2 is satisfied, the n;i-th ΔKAST value is set to a third predetermined value ΔKAST3 which is smaller than the second predetermined value ΔKAST2 (step 406), and this routine is ended.

FIG. 5 shows the first and second predetermined coefficients RASTI and RAST applied to the equations (2) and (3), respectively.
2 shows a flowchart of a subroutine for setting 2.

First, in step 501, the intake temperature ゛I゛^INT is
It is determined whether the temperature is higher than a first predetermined temperature T^^S (for example, 0°C) and lower than a second predetermined temperature T^cyw (>'l'AAsT, for example, 20°C). The intake temperature 1'
AINT is determined when the final '1'' DC signal pulse occurs in the starting mode, and reflects the intake pipe wall temperature, and also reflects the atmospheric temperature if the time from engine stop to engine start is long. That is, in the determination of step 501 of n:j, the first predetermined temperature T^^ST is determined based on the atmospheric temperature whether the season corresponds to the warm season in which the low atomization fuel is used. Therefore, at the second predetermined temperature 'I゛^, TW is maintained even if the 11:j distributed atomized fuel is used because the intake pipe wall is sufficiently warmed, for example at the time of a high temperature restart. This is to determine whether or not good atomization characteristics are ensured.

If the answer to step 501 is negative (NO), that is, '1゛^
INT≦'I''AAST or']' A I NT≧'
! 'When AKTW is established, it is determined that the low atomization fuel is not being used, or even if it is used, the intake pipe wall is sufficiently warmed and the atomization characteristics of the fuel are in good condition. and the first and second predetermined coefficients RA
STI, I? ^ST2 is the second one for normal use.
1α1? While setting ^sr+-t+, I Buddha 5T2-It (e.g. 0, 7.0.4 respectively) (step 5
02), affirmative (Yes), i.e. 1°AAsT< T^n
When TW holds that u<1'8, the low atomization fuel is being used, and 11. When the intake pipe wall temperature is low and the atomization characteristics of the fuel are determined to be low, the above 1. Asr
+ and RAST2 values to the second (1αRASTI−
11, the first value larger than RAST2-11 @
AST +-^ and RAsy2-^ (for example, 0, 8.0, and 5, respectively) are set (step 503), and this routine ends.

Returning to FIG. 2, in step 204 following step 202 or 203 in 11.i, it is determined whether the increase coefficient KAST calculated in these steps is greater than 1.0. If the answer is 17 (Yes), it is determined whether the air conditioner (11ΔC) switch 17 is in the on state (step 205). If the answer is negative (No), that is, the near conditioner is not operating, the current value KASTI+ of the increase coefficient is set to the KAST value calculated in step 202 or 203 (step 2
06).

On the other hand, the answer to step 205 of 1fiF is affirmative (Yes).
That is, when the near conditioner is operating, the current value KAsTn of the increase coefficient is added to the KAST value calculated in step 202 or 203, and a predetermined increase correction coefficient KuAe (for example,
In step 207), the program is terminated.

In this way, when the near conditioner is operating, the increase coefficient KA
The reason why ST is set to a larger value (1e1) is that during the operation, the control valve 6
Since the amount of intake air is increased by increasing the amount of current I supplied to the
-L and burn! This is to prevent the supply air-fuel ratio from becoming leaner due to a decrease in the atomization characteristics of the fuel oil.

If the answer to step 204 is negative (NO), that is, KAST
When ≦1.0 holds true, the KASTIII' is reset to the value 1.0 (step 208) and the program is terminated.

Is it increased like ■■2? , the coefficient KAST is calculated, and as a result, the increase coefficient KAST decreases along the solid or broken line shown in FIG. That is, increase ffi
The coefficient KAST is set to its initial value STO according to the engine cooling water temperature '1゛W just before the end of cranking, and then KAsil+1 is the second discrimination value] 5TRI
If the subtraction constant term ΔKAsT is larger than
By applying a predetermined 1 straight line Δl ^sTI, the KAsd line is reduced by the largest reduction degree, and the KAsd line is reduced to the discriminant value K.
smaller than ASTRI and the third discrimination (fLKAs
If it is larger than rn, the second predetermined value ΔKAST2 is applied as the subtraction constant term ΔKAsr, so that the KAST value is reduced by a smaller degree of reduction, and the KAST value is further reduced by the third predetermined value ΔKAST2.
If it becomes smaller than the discriminant value KASTI42, the third predetermined value ΔKASTI3 is applied as the subtraction constant term ΔKAST, thereby reducing the degree of decrease by an even smaller degree (the solid line in FIG. 6) or the broken line 11. ).

In addition, in this case, the subroutine shown in FIG.
J first and second predetermined coefficients RASTI, RAST2
, the smaller second value RASTI-B, RAS
When T2-B is selected, the first and second discriminant values KASTI! are determined according to equations (2) and (3). l, KAsr
KASTI where g2 is smaller! 1-R, KAS engineering! 2
-11, the increase factor KAST moves along the solid line 1 in FIG. 6 at t16, while the first (fi
RAsrt-^, When RAST2-A is selected, the first and second discrimination 1111KAsTI! l.

KASTI-A, KAST with larger KASTR2
By setting it to 2-A, the increase coefficient KAs changes according to the broken line 11 in the figure.

Therefore, in the warm season when low atomization fuel is used, the atmospheric temperature is high and the intake air i11! '1'＾fN
Since T is high, r^^ST<'I''^INT holds, and the answer to step 501 in Fig. 5 is usually 11 constant (Yes.
), and by executing step 503, the increase coefficient KAsT changes along the broken line in FIG. As a result, after starting when low atomization fuel F is used, the degree of decrease in the increase coefficient KAST becomes a small value from the time of use, so that the amount of fuel increased after starting is indicated by the broken line in the figure. (J increase correction is made to compensate for the increase in time for l = I fuel to arrive at the intake pipe wall due to the poor atomization characteristics mentioned above, and to make the supply air-fuel ratio leaner temporarily. 11- can be prevented, and therefore, the low F of the engine rotational speed at this time and the engine stall caused by this can be prevented.

In addition, in this case, as the increase coefficient 1<AST changes along the broken line 1■ in Fig. 6, 1 ^ 5T = 1
．． Since the period of time until the fuel t' reaches 0 after starting is increased, a reliable and good combustion state can be ensured at low engine temperatures.

On the other hand, in seasons other than warm weather when low atomization fuel is not used, the atmospheric temperature is low and '1゛^INT≦1'AAs
If the temperature of the intake pipe wall is sufficiently high as in the case of a high-temperature restart, the 5th Step 5 in the diagram
If the answer to 01 is negative (No), step 502 is executed, and the increase ffi coefficient KAST changes along the solid line I in FIG. If the temperature of the intake pipe wall is high enough, low atomization fuel ↑'
) fJ (even if it is used, the degree of atomization will be high, so
This state is changed to the second predetermined temperature 'I゛8KTW as described above.
By determining this and changing the increase coefficient KAST to a smaller value, it is possible to reduce the amount of fuel to prevent engine stalling and the like.

Moreover, the solid line III in FIG. 6 is the initial (lI'!KAsTo
It shows the tllI shift of the increase coefficient KAST when is smaller than the first discrimination 11αKAsr2o.

In addition, in this example, the increase coefficient AST is set to 1'
L) Although an example has been shown in which the amount of fuel H is decreased every time a C signal pulse occurs, that is, the amount of fuel H is increased over a predetermined number of engine rotations after starting, the present invention is not limited to this. The amount of fuel may be decreased at each time interval, and the amount of fuel may be increased at a predetermined period after startup.

(Effects of the Invention) As described in detail below, the present invention provides the following effects.

According to claim 1, for the warmer in which low atomization fuel is used, the fuel consumption increased after startup is further corrected to increase, so that at this time (!(supply air combustion is transient) Therefore, it is possible to reliably prevent a decrease in the engine rotational speed and an engine stall caused by this, and to obtain good starting characteristics.

In addition, according to Claim 2 of 1II11, it is possible to obtain the same effect as in Claim I of Claim 1-, and even in a warm child in which low atomization fuel is used, the intake pipe wall is When the temperature is high and good atomization characteristics are ensured, the amount of fuel can be reduced to prevent engine stalling and the like.

Furthermore, according to claim 3, since the fuel increase period after startup is extended in the warm engine in which low atomization fuel is used, a reliable and good combustion state can be ensured at low engine temperatures.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is an overall configuration diagram of a fuel supply control device, and FIG. 2 is a flowchart 1 of a subroutine for calculating the post-startup singing coefficient KAST according to the present invention.
・, Fig. 3 is a diagram showing the KAST table for setting the initial value of the after-start increase coefficient 1 (AST), Fig. Flowchart 1 of the subroutine for setting a predetermined coefficient applied to determine whether the subtraction constant value △I<AsT (II'I is set), FIG. 6 shows how the increase m coefficient KAsT changes after startup. It is a diagram. 1... Internal combustion engine, 9... Electronic control unit □ (+", CU) (increase song correction means, increase period extension means), I4... Intake air temperature (1゛^) sensor (atmospheric temperature sensor), KAsT...Finger increase coefficient after startup (increase rl 110
, i'AAsT...first predetermined temperature (predetermined (ll'i
), 'I'AKTW...Second predetermined temperature (second predetermined ((6).

Claims (1)

[Scope of Claims] 1. 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 that gradually decreases over a predetermined period after the start of the internal combustion engine or over a predetermined number of engine rotations. The method is characterized by comprising an atmospheric temperature detector that detects atmospheric temperature, and an increase correction means that increases the increase value when the atmospheric temperature detected by the atmospheric temperature detector is equal to or higher than a predetermined value. Fuel supply control device for internal combustion engines. 2. The fuel supply control device for an internal combustion engine according to claim 1, wherein the increase correction means increases the increase value when the atmospheric temperature is above the predetermined value and below a second predetermined value. . 3. In a fuel supply control device for an internal combustion engine that supplies an increased amount of fuel to the engine based on an increase value that gradually decreases over a predetermined period of time or a predetermined number of engine rotations after the internal combustion engine starts, the atmospheric temperature is detected. and an increase period extension means for extending the predetermined period or increasing the predetermined number of engine revolutions when the atmospheric temperature detected by the atmospheric temperature detector is equal to or higher than a predetermined value. A fuel supply control device for an internal combustion engine, characterized in that: