JPS6088830A - Method of controlling operation characteristic quantity for operation control means of internal-combustion engine - Google Patents

Abstract

PURPOSE:To smoothly operate an engine, by changing two engine operation parameters for each other to use one of them when the engine is shifted to a low-load operation from another operation. CONSTITUTION:A throttle valve sensor 17 and an absolute pressure (PBA) sensor 12 are provided so that these two sensors are used to control an engine when it is shifted from a low-load operation from another operation. Until a control quantity corresponding to the degree of opening of a throttle valve and a control quantity corresponding to the absolute pressure PBA become equal to each other, the engine is controlled on the basis of the former control quantity. After both the control quantities have become equal to each other, the engine is controlled on the basis of the latter control quantity. Such low-load operation of the engine as idling is thus smoothed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling an operating characteristic quantity of an operation control means of an internal combustion engine, and in particular, to optimize an operating characteristic quantity control value of an operation control means during a predetermined low load operation of the engine according to the operating state of the engine. The present invention relates to a method of controlling an operating characteristic quantity in order to smoothen the operation of an engine by setting the value to a certain value.

Conventionally, operating characteristic quantities of an operation control means for controlling engine operation according to engine control parameters representing load conditions, such as intake pipe absolute pressure and engine rotational speed, are supplied to an engine by a fuel supply amount control device, for example. amount of fuel,
Determine the spark ignition timing controlled by the ignition timing control device, the exhaust gas recirculation amount controlled by the exhaust gas recirculation control device, etc.
A method of correcting the thus determined operating characteristic quantity according to the intake air temperature, engine cooling water temperature, etc. to accurately set the required operating characteristic quantity is disclosed in, for example, JP-A-57-137633 and JP-A-53.
It is known from No.-8434 etc.

In addition, the volume of the engine's intake passage, especially the volume of the passage on the downstream side of the throttle valve, is designed to be large to minimize the pressure loss of the intake air that occurs when the intake air flows through the intake passage, thereby increasing the filling efficiency of the intake air. There are also known methods for improving engine characteristics such as increasing engine output.

However, increasing the total volume of the intake passage downstream of the throttle valve does not reduce the degree of change in the absolute pressure in the intake pipe with respect to the degree of change in engine speed during low-load operation such as when the engine is idling. According to the above-mentioned method of determining operating characteristic quantities according to the absolute pressure in the intake pipe and the engine speed (generally referred to as the "speed density method", hereinafter simply referred to as the "SD method"), the amount of fuel, etc. It is difficult to accurately set the operating characteristic quantity in accordance with the engine operating condition, and a hunting phenomenon of the engine speed is likely to occur. Therefore, the throttle valve upstream pressure PA
' and downstream pressure PBh (P n A/'P
A') is the critical pressure ratio (0,52
8) During low-load engine operation, the amount of intake air passing through the throttle valve is equal to the pressure Pn on the downstream side of the throttle valve.
Focusing on the fact that it can be determined only by the opening area of the throttle valve without depending on A method of accurately detecting the intake air needle and calculating operating characteristics such as fuel flow rate based on the detected intake air amount (hereinafter referred to as the "KMe method") was published in Japanese Patent Publication No. 52-6414.
proposed by.

However, when a predetermined low-load operating state such as an idle operating state of the engine is detected and it is detected that the engine has transitioned from a state other than the predetermined low-load operating state to the predetermined low-load operating state, for example, the fuel injection amount is set. The SD method described above
When switching from the KMe method to the KMe method, engine shock or engine stall may occur due to sudden changes in the fuel injection amount.

Figure 1 is a diagram explaining how these inconveniences occur. Now, the engine is accelerating from idle point A to B.
Assume that the vehicle reaches the idle point A, then stops the start and returns to the idle point A again. Idle point A is on the operating line where the throttle valve opening is constant and the throttle valve is in the fully closed position. Throttle valve opening degree IT)l is fully closed position・a
When the valve is opened from 1 to θ2, the engine speed increases once along the operating line, but the engine load increases due to the engagement of the clutch, so the engine speed decreases and the engine speed increases along the operating line where the throttle valve opening is constant. Reach point B at . When the engine overflows into the operating line (2), the throttle valve is opened and the engine is in an accelerating state, so the fuel injection amount to the engine is set by the SD method.

Next, when the throttle valve is closed from the valve opening voltage transformation θ2 to -al and the clutch is turned off again, it is determined that the engine is in a predetermined low-load operating state. The predetermined low-load operating state in the present invention is, for example, when the throttle valve opening is less than or equal to a predetermined opening for determining the acceleration state of the engine, and the absolute pressure in the intake pipe on the downstream side of the throttle valve causes a sonic flow in the throttle valve portion. When it is detected that the engine is in the predetermined low-load operating state in an operating state in which the reference pressure PRAC is lower than the reference pressure PRAC and the engine speed is below the predetermined rotation speed NIDL, which is higher than the idling speed. If the method for setting the fuel injection amount is immediately switched from the SD method to the KMe method, the engine at 8 points will have a fuel amount corresponding to the throttle valve opening/al, that is, the throttle valve fully closed steady operation line. Since only the amount of fuel corresponding to point B', which is the same engine speed as point B on l, is supplied, the air-fuel mixture supplied to the engine becomes uniform, and the engine speed reaches the operating line H. This can cause the engine to stall in some cases.

In addition, the operating line ■ in Fig. 1 shows the operating line when the engine is started, and the operating line differs from the throttle valve fully closed steady operating line θl due to starter operation and subsequent engine self-sustaining operation from the 0 point indicating the engine stopped state. ■Head to idle point A. This is because the volume of the downstream passage of the engine throttle valve is designed to be large as described above, so that the pressure inside the intake pipe does not drop suddenly. When the absolute pressure PBA in the intake pipe falls below the reference pressure FBAC and the predetermined low-load operating state is detected (
If the fuel amount setting method is immediately switched from the SD method to the KMe method, the engine at point D will have the same engine speed as at point D on the throttle valve fully closed steady operation input θ1. If only the amount of fuel corresponding to point D' is supplied, as mentioned above, the mixture will become uniform and the engine will be delayed in reaching the idle point (
1), an engine stall may occur.

Further, suppose that the engine is in a steady operating state, for example, going down a long gentle downhill slope, and remains at point E on the throttle valve fully closed steady operating line θ,1 in FIG. If the engine speed suddenly drops due to sudden application of engine brake under such operating conditions, the intake pipe absolute pressure P
Person B does not rise rapidly because the intake passage is designed to have a large volume, so it overflows into the operating line (2) on the low load side from the operating 2-in θ1 in FIG. 1 and heads toward the idle point A. While the engine is moving toward the idle point A along this operating line
If the fuel amount setting method is immediately switched from the SD method to the KMe method when the predetermined low load operating state is detected, contrary to the case at the time of starting mentioned above, an excessive amount of fuel may be generated. A sudden change in the amount of fuel supplied to the engine causes so-called engine shock, which disturbs the operating condition.

The present invention has been made to avoid such inconveniences, and includes a method for electronically controlling the operating characteristics and quantities of the operating control means of an internal combustion engine, which includes: detecting a predetermined low-load operating state of the engine; When the engine is in the predetermined low load operating state, a first engine operating parameter value representing the engine load state is detected, and the control value of the operating characteristic quantity is determined based on the detected first engine operating parameter value. and when the engine is in a state other than the predetermined low load operating state, detecting a second engine operating parameter value representing the engine load state, and performing the operation based on the detected second engine operating parameter value. When determining the control value of the characteristic quantity and detecting that the engine has transitioned from a state other than the predetermined low-load operating state to the predetermined low-load operating state, both the first and second engine operating parameter detected values Until the second operating characteristic quantity control value, which is obtained by requesting the first and second operating characteristic quantity control values, respectively, substantially matches the first operating characteristic quantity control value, the second operating characteristic quantity control value is A multi-operating characteristic quantity control value is determined based on the engine operating parameter detected value, and the operating characteristic quantity of the operation control means is controlled to the thus determined operating characteristic quantity control value. An object of the present invention is to provide a method for controlling an operating characteristic quantity of an operation control means for an internal combustion engine, which achieves smooth and stable operation.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram schematically showing the entire fuel injection control device for an internal combustion engine to which the method of the present invention is applied. Reference numeral l indicates, for example, a four-cylinder internal combustion engine, and the engine yl has an open end. Intake pipe 3 and exhaust pipe 4 with air cleaner 2 attached
is connected.

A throttle valve 9 is arranged in the middle of the intake pipe 3, and an air passage 8 that opens into the intake pipe 3 downstream of the throttle valve 9 and communicates with the atmosphere is arranged. An air cleaner 7 is attached to the open end of the air passage 8 on the atmosphere side, and an auxiliary air amount control valve (hereinafter simply referred to as "control valve") 6 is disposed in the middle of the air passage 8. The control valve 6 is a normally closed solenoid valve, and is composed of a solenoid 6a and a valve 6b that opens the air passage 8 when the solenoid 6a is energized.
a is electrically connected to an electronic control unit (hereinafter referred to as "EcU") 5.

A fuel injection valve 10 is provided between the engine l of the intake pipe 3 and the opening 8a of the air passage 8.
0 is connected to a fuel pump (not shown) and EC
Electrically connected to U3.

A throttle valve opening sensor 17 is installed in the throttle valve 9, an intake air temperature sensor 11 and an intake pipe absolute pressure sensor 12 are installed downstream of the opening 8a in the air passage 8 of the intake pipe 3, and an engine cooling water temperature sensor 12 is installed in the engine 1 body. A sensor 13 and an engine speed sensor 14 are respectively attached, and each sensor is
C (electrically connected to J5. Reference numeral 15 indicates an electrical device such as a headlight, a brake light, a radiator cooling fan, etc., and one connection terminal of the electrical device 15 is electrically connected to the ECU 3 via a switch 16. while the other connection terminal is connected to the battery 19. Reference numeral 18 indicates an atmospheric pressure sensor that detects atmospheric pressure, and an atmospheric pressure signal from the atmospheric pressure sensor 18 is supplied to the ECU 3.

Next, the operation of the fuel injection control device configured as described above will be explained.

Respective engine operating parameter signals are supplied to the ECU 3 from the throttle valve opening sensor 17, intake air temperature sensor 11, absolute pressure sensor 12, cooling water temperature sensor 13, engine speed sensor 14, and atmospheric pressure sensor 18. determines the operating state in which auxiliary air should be supplied by the control valve 6 based on these engine operating parameter signals and the electrical load state signal from the electrical device 15, sets the target idle rotation speed, and controls the supply of auxiliary air. When the desired operating state is determined, the amount of auxiliary air, and therefore the valve opening duty ratio DoUT of the control valve 6, is calculated in accordance with the difference between the target idle speed and the actual engine speed so as to minimize this difference, and the calculation is performed. A drive signal is supplied to the control valve 6 to operate the control valve 6 according to the value.

The solenoid 6a of the control valve 6 has the valve opening duty ratio DO.
The valve 6b is energized for a valve opening time corresponding to the UT to open the air passage 8, and a predetermined amount of air according to the valve opening time flows into the engine 1 via the air passage 8 and the intake pipe 3. supplied to

When the amount of auxiliary air is increased by lengthening the opening time of the control valve 6, the amount of air-fuel mixture supplied to the engine 1 increases, the engine output increases, and the engine speed increases. Conversely, control valve 6
If the full valve opening time is set, the amount of air-fuel mixture supplied will decrease and the engine speed will drop.

By controlling the amount of auxiliary air, that is, the opening time of the control valve 6, the engine speed during idling is maintained at the target speed.

On the other hand, the ECU 3 calculates the fuel injection time TOUT of the fuel injection valve 12 based on the above-mentioned various engine operating parameter signal values and in synchronization with the TDC signal according to the formula shown below.

Tour='I'1xK1 +,=-・-・-...
(1) Here, Ti indicates the basic injection time, and the basic injection time +11i is determined by the SD method depending on whether the engine is in a region where predetermined idle operating conditions are satisfied, as will be described in detail later. and KMe method.

The correction coefficients or correction values Kl and 2 are the various sensors mentioned above,
That is, the throttle valve opening sensor 17, the atmospheric pressure sensor 1
8. A correction coefficient or correction value calculated according to an engine operation parameter signal from an engine operation parameter sensor such as the intake air temperature sensor 11, and the correction coefficient Kl is given by the following equation, for example.

Kl=KTAXKPAXKTWXKWOTx=-・・
−・・−(2) Here, KTA is the intake air temperature correction coefficient, KP
A is an atmospheric pressure correction coefficient, and these correction coefficients KTA
, KFA is set to an appropriate value for each method using separate calculation formulas for the SD method and the KMe method, as will be described later.

Further, KTW is a fuel increase coefficient, KWO, which is set according to the engine water temperature Tw detected by the cooling water temperature sensor 13.
T is a constant and is the enrichment coefficient when the throttle valve is fully open.

ECU3 sets the fuel injection time TOUT as described above.
A drive signal for opening the fuel injector 12 based on this is supplied to the fuel injector 12.

FIG. 3 is a diagram showing the circuit configuration inside the ECU 3 of FIG.
The output signal from the engine rotation angle position sensor 14 in FIG. 2 is waveform-shaped by a waveform shaping circuit 501, and then
As a signal, the central processing unit c (hereinafter referred to as 1'-CPUJ)
503 and is also supplied to the Me counter 502. The Me counter 502 counts the time interval from when the previous 'I' DC signal was input from the engine rotation angle position sensor 14 to when the current 'I' DC signal was input, and the counted value Me is equal to the engine rotation speed Ne. is proportional to the reciprocal of

1vre counter 502 supplies this count Me to CPU 503 via data bus 510.

Throttle valve opening sensor 17, intake pipe absolute pressure PBA sensor 12, intake temperature sensor 11, and atmospheric pressure sensor 1 shown in FIG.
After each output signal from various sensors such as 8 is corrected to a predetermined voltage level by a level correction circuit 504, it is sequentially supplied to an A/D converter 506 through a multiplexer 505. The A/D converter 506 sequentially converts the output signals from the aforementioned sensors into digital signals and supplies the digital signals to the CPU 503 via the data bus 5101r.

The on-off signals of the switches 16 of the electrical device 15 in FIG.

5071. yy dumb yri*, <Memo IJ (RAM) 5
08 and drive circuits 509 and 511.
The AM508 temporarily stores the calculation results of the CPU 503, and the I(0M507) stores the control program executed by the CPU 503f, a basic fuel injection time map, etc.

The CPU 503 determines the engine operating state according to the various engine parameter signals mentioned above according to the control program stored in the ROM 507, and also determines the electrical load state on the engine according to the on-off signal of the electric device 15, thereby controlling the engine. The valve opening duty ratio DoUT of the control valve 6 is calculated according to the load state.

The CPU 503 determines the valve opening duty ratio DO of the control valve 6 described above.
A control signal corresponding to the calculated value of the UT is supplied to the drive circuit 511 via the data bus 510, and the drive circuit 511 supplies the control valve 6 with a drive signal for turning the control valve 6 on and off.

Further, the CPU 503 calculates the valve opening time To UT of the fuel injection valve 10 according to the above-mentioned various engine parameter signals, as will be described in detail later, and drives a control signal according to this calculated value via the data bus 510. supplying the circuit 509;
The drive circuit 509 operates the fuel injection valve 10 according to this control signal.
A drive signal for opening the injection valve 10 is supplied to the injection valve 10.

FIG. 4 is executed by the CPO 503 of FIG. 3 every time a pulse of the TDC signal is generated. Valve opening time T' of the fuel injection valve 10
OUT1 (This is a program flowchart showing a method of calculating.

First, in step 1 of FIG. 4, the basic fuel injection time 'piMAp f is determined by the SD method. T by this SD method
The iMAP value is determined by converting the TiMAp value according to the detected intake pipe absolute pressure PBA and engine speed Ne to R in Fig. 3.
This is done by reading from the basic fuel injection time map stored in OM507. Next, in steps 2 to 4, the engine determines whether a predetermined idle operating condition is satisfied. In step 2, it is determined whether or not the engine rotation speed Ne is less than or equal to a predetermined rotation speed NIDL (for example, 101000 rpm), and if the determination result is negative (No), the idle operating condition is not satisfied, and steps 5 and 6, which will be described later, are immediately performed. If the determination result in step 20 is affirmative (Yes), proceed to step 3, where it is determined whether or not the intake pipe absolute pressure PBA is lower than the reference pressure PRAC on the low engine load side, that is, below the reference pressure PRAC. Pressure PBAC is the absolute pressure P in the intake pipe on the downstream side of the throttle valve relative to the absolute pressure PA' in the intake pipe on the upstream side of the throttle valve 9.
The ratio of BA (PBA/PX) is set to determine whether or not the intake flow velocity passing through the throttle valve 9 is equal to or less than the critical pressure ratio (0,528) at which the flow becomes sonic flow, and is the reference pressure. FBAC is given by the following equation.

PRAC = PA'x (critical pressure ratio) = PA'X Here is the specific heat ratio of air (=1.4), and the absolute pressure PA' in the intake pipe upstream of the throttle valve 9 is approximately as shown in Figure 2. Since the atmospheric pressure PA is equal to the atmospheric pressure PA detected by the sensor 18, the above relationship is obtained.

If the determination result in step 3 is negative (NO), the predetermined idle operation condition is not satisfied and the process proceeds to steps 5 and 6, and if the result is affirmative (Yes), the process proceeds to step 4. In step 4, the valve opening θTH of the throttle valve 9 is set to a predetermined opening θ'I.
It is determined whether or not it is below DLH. The reason for this determination is that when the throttle valve 9 shifts from an idling operating state in which the throttle valve 9 is in a substantially fully closed position to an accelerating operating state in which the throttle valve is rapidly opened, the engine speed and intake pipe absolute If the acceleration operation state is determined only based on pressure changes, the detection of the acceleration operation state will be delayed due to the response delay of the absolute pressure sensor, etc. Therefore, the acceleration operation state is detected based on the throttle valve opening, and the acceleration operation state is determined based on the throttle valve opening. This is because, if detected, it is necessary to calculate an appropriate amount of acceleration fuel using the SD method and supply this fuel amount to the engine. If the determination result in step 4 is negative (No), the predetermined idle operation condition is not satisfied and the process proceeds to steps 5 and 6, and if the result is affirmative (Yes), the process proceeds to step 7.

In step 5, which is executed when the idle operating condition is not satisfied, the current value Xn of the program control variable described later is set to zero, and then the atmospheric pressure correction coefficient KPAI and the intake air temperature correction coefficient KTAI applied in the SD method are set. Then, in order to apply these coefficients to the above equation (1) together with the basic fuel injection time TtMAp determined in step 1, a multiplication term Ti*KpA·KTA is calculated (step 6).
.

Ti @KpAsKr*=TiMAp−KpAi II
KTAI...Song (4) The atmospheric pressure correction coefficient KPAI applied to the SD method is determined by the following equation, as disclosed in, for example, Japanese Patent Laid-Open No. 58-853137.

In particular, PA is the actual atmospheric pressure (absolute pressure), PAO is the standard atmospheric pressure, ε is the compression ratio, and is the specific heat ratio of air.

The atmospheric pressure correction coefficient KPAI is based on the theory that the amount of air taken into the engine cylinder during one intake stroke is based on the absolute pressure in the intake pipe, PB, and the absolute pressure in the exhaust pipe, which can be considered to be approximately equal to the atmospheric pressures P and A. In order to keep the air-fuel ratio constant,
Actual atmospheric pressure P for intake air amount at standard atmospheric pressure PAO
Since it is sufficient to increase or decrease the fuel amount at the same ratio as the ratio of the intake air amount in A, the above formula (5) can be obtained.

Note that according to equation (5), when PA<PAO, KPAI>1. In other words, at high altitudes, the atmospheric pressure P^ is the standard atmospheric pressure P
When AO decreases, the absolute pressure in the intake pipe PB is the same as on a flat ground.
Under condition A, the amount of intake air increases. Therefore, if the fuel amount, which is set as a function of the intake pipe absolute pressure PBA and the engine speed, is applied under low atmospheric pressure such as at high altitudes, the mixture will not become uniform, and the increase coefficient KPAI will change the mixture concentration. Unification is prevented.

On the other hand, the intake temperature correction coefficient KTA1 applied to the SD method is
For example, as disclosed in Japanese Patent Application Laid-Open No. 58-88436,
It is determined by the following formula.

Here, TA is the intake air temperature (℃) flowing in the intake pipe,
'f'AO is a calibration variable, for example 50℃
is set to CTAMAP is a gear repration/coefficient and is set to a fixed value (for example, 1.26X1) depending on the engine characteristics.
0). CTAMAP(TA
-TAO) is a smaller value than 1, so approximately KTA1=l-CTAMAP(TA-'l'Ao)
-4-・(7) can be concluded.

All of the determination results in steps 2 to 4 are positive (Yes).
) If the predetermined idle operating conditions are met,
First, in step 7, the basic fuel injection time 'f is calculated using the KMe method.
Calculate 'ic. Basic injection time T by this KMe method
ie is determined by the following formula.

T i =K(A) ・Me ・−(8) Here K (
A) is set according to the equivalent opening area of the throttle part of the intake passage, that is, the sum of the opening areas of the throttle valve 9 and the control valve 6, and the opening area of the throttle valve 9 and the control valve 6 is determined by the throttle valve opening. Valve opening signal value from sensor 17 and the CP
Each is determined based on the valve opening duty ratio of the control valve 6 calculated by U503. Me is the TDC signal pulse generation time interval measured by the Me counter 502 in FIG. The reason why the basic injection time Ti can be expressed by equation (8) is that the amount of intake air per unit time passing through the throttle part of the intake passage such as the throttle valve is such that the pressure ratio before and after the throttle part is the critical value. Atmospheric pressure PA, intake air temperature T
When A is constant, it is given by a function only of the equivalent opening area of the throttle part, and - the amount of intake air taken into the engine cylinder during the intake stroke is the reciprocal of the engine speed Ne, and is therefore proportional to the Me value. By doing.

Next, proceeding to step 8, it is determined whether the fuel injection time was determined by the KMe method in the previous loop (the case determined by the KMe method is hereinafter referred to as "idle mode 1"), and if the previous loop was already in idle mode. If there is (if the determination result is affirmative (Yes)), the process proceeds to step 14 without performing the determinations in steps 9 to 130 described later, and if the previous loop is not still in idle mode (if the determination result in step 8 is negative (NO)). ), the determinations in steps 9 to 13 according to the present invention are performed.

In steps 9 and 11, the atmospheric pressure correction coefficient KPAI and intake air temperature correction coefficient KTAI applied to the SD method are determined in the same manner as in step 6, and at the same time, the atmospheric correction coefficient KPA2 and intake air temperature applied to the KMe method are determined. A correction coefficient KTA2 is set.

These coefficients KPA2 and KTA2 are calculated as follows.

Pressure P in the intake pipe upstream of the throttle part such as the throttle valve in the intake pipe
When the downstream pressure PBAO ratio (PBA/PA ratio) to A' is less than the critical pressure ratio (0,528), the intake air passing through the throttle section becomes a sonic flow, and the intake air amount...
... (9) In particular, A is the equivalent opening area (-
)C is the correction coefficient determined by the shape of the aperture, etc., and PA is the atmospheric pressure (
PA#Pmu', w+Hg), is the specific heat ratio of air, B is the gas constant of air, and 'I'AP is the intake air temperature just before the throttle part (1
), g is the gravitational acceleration (m/sec) The ratio between the intake air amount GaO at standard atmospheric pressure Pm 0 and the intake air amount Ga for two people at arbitrary atmospheric pressure is given by the intake air temperature TAF and the opening area A. When the ratio is constant, Ga PA Gao PAO is given, and by changing the amount of fuel supplied to the engine at the same ratio as this intake air amount ratio, the air-fuel ratio can be kept constant.Therefore, the fuel flow rate Gf is the standard value. Atmospheric pressure P
It is given by from the fuel flow rate Gfo at ^O (760ymnHg). Here, the atmospheric pressure correction coefficient KpA2 can be theoretically expressed as 2 people KPA2=L. However, in practical use, it can be expressed as the above formula %, taking into account various errors caused by the shape of the intake passage, etc. Here, CPA is an experimentally set Mbration variable.

In addition, from the above formula α0, when PA<760Hg, KPA2<
It becomes 1. That is, in the KMe method, the amount of intake air is determined only by the equivalent opening area A of the intake passage restrictor such as the throttle valve, with reference to the standard atmospheric pressure PA0. 760y
+aHg), the amount of intake air is atmospheric pressure FA
However, if the fuel amount is set according to the opening area A described above, the air-fuel mixture becomes richer, contrary to the case of the SD method.

The correction coefficient KPA2 mentioned above is for preventing such enrichment.

Next, in the above equation (9), if the atmospheric pressure PA and the opening area A are constant, the temperature upstream of the aperture part is the reference temperature 'I'AF
The air-fuel ratio can be kept constant by changing the amount of fuel supplied to the engine at the same ratio as the intake air amount GaO when the temperature is O and an arbitrary temperature. Therefore, the fuel flow rate Gf is given by the flow rate Gfo at the reference temperature TiF4. Intake air temperature correction coefficient K
When TA2 is expressed as , KTA2 is approximately expressed by the following expression by modifying the above expression.

・・・・・・・・・(B) KTA2 determined by formula (B) is the intake air temperature TA upstream of the throttle part.
It is given as a function of F. However, the temperature upstream of the drawing part T
It has been experimentally confirmed that the function between AP and downstream temperature TA is approximately given by the following equation under idling operating conditions.

TA F = aTA+b ・・・・・・・・・ (6
) where a and b are constants. TAFO=aTAO+b
Considering that, by substituting formula (2) into formula (b) and rearranging, the open formula is: KTA2=1-aa(TA-'I'AO):1-CTA
It can be expressed as C(TA-TAO) (2), and the intake air temperature correction coefficient KTA2 can be calculated by the simplified formula (to).

The correction coefficient determined as described above and the basic injection time TiMAp determined in steps 1 and 7 above.

TicK! , 9. Multiplication terms Ti and KpA that can be claimed in the SD method
.

Determine whether the value of KTA is substantially equal to that claimed by the KMe method. That is, in step 9, the product value 'l['iMAp, KPAI, KTAI by the SD method is KM
Product value jI'ic*Kpm2・KTA2 requested by e method
In step 11, a predetermined lower limit coefficient C is applied to the product value Tic@KpA2*KT^2 by the KMe method.
Determine whether the value is larger than the value multiplied by L (for example, 0.95) 0 The above-mentioned predetermined upper and lower limit coefficients CH and Cx are experimentally set to optimal values in order to smooth and stabilize engine operation. be done.

If the determination results in steps 9 and 11 are both affirmative (Yes), the above product value TiM*p determined by the SD method
-KPAI IIKTAI is the product value TiM by KMe method
ApeKpA2・KTA2 is determined to be substantially equal to ApeKpA2・KTA2, and the process proceeds to step 14, where the basic fuel injection time Tic and the correction coefficients KPA2, I(TA2
In order to apply the above equation (1), the multiplication term Ti IIKP
A Assign Tic*Kpmu2・KTmu2 value to IIKTA.

Ti・KPA aKr*=Tic 1lKPA2・KT
A2・・・・・・α觀Figure 5 shows the determination results from steps 9 to 130 in Figure 4 in terms of intake pipe absolute pressure PR and engine rotational speed similar to the engine operating diagram in Figure 1. This will be explained using an operating diagram, and if the determination results in steps 9 and 11 above are both affirmative (Yes), this means that the engine operating point at the previous loop has changed from, for example, point A or point B in the diagram to this time. During the loop, the throttle valve opening is smaller than the predetermined opening θIDLH, for example, at point a or b, which is substantially on the operating line of constant opening θT (point a or b is equal to the upper and lower limit coefficients OH, CL). Diagram 2 set correspondingly
(within the dashed line open area of the book).

Therefore, if such a determination result is obtained, even if the fuel amount setting method is switched from the SD method to the KMe method, the amount of supplied fuel will not change suddenly, thus ensuring smooth engine operation when switching to the fuel control method. be done.

Next, if the determination result in step 9 is negative (No), set the current value Xn of the program control variable to 3 (step 10), and set the previous value Xn-1 of this program control variable.
It is determined whether the difference between the current value Xn and the current value Xn is 1 (step 13). In this way, using program control variables to determine whether the difference between the current value and the previous value is 1 is because the engine operating point detected during the current loop is the same as the operating point during the previous loop. On the other hand, this is to determine whether the valve opening θT, which is the throttle valve opening value detected during the current loop, has changed substantially across the constant operation line.

That is, for example, in the previous loop, the engine did not meet the predetermined idle operating condition (in this case, step 5 of the previous loop
In this loop, the determination result in step 9 is negative (No) and Xn = 3 (
If step 10) is set, if the determination result in step 9 is negative (No) in both the previous loop and the current loop, (
In this case, Xn = Life E-+e, p-*f
), in such a case, the determination result in step 13 is negative (No), and the calculation of the fuel injection time is continued using the SD method (step 6).

On the other hand, if the determination result in step 9 was negative during the current loop, the I) If (Xn-1
= 2), or conversely, if step 12 was executed during the current loop (Xn = 2), or if step 10 was executed during the previous loop (Xn-1 = 3), then the difference between the previous loop and the current loop is This means that the engine operating line has crossed the constant valve opening θT operating line, which is the operating line C-+ (, D-+d) in Figure 5, that is, the SD method between the previous loop and the current loop. Injection time and KMe calculated by
means that it was substantially consistent with that according to the law;
In such a case, it is preferable to immediately switch to fuel control using the KMe method. Therefore, if the determination result in step 13 is affirmative (Yes), the calculation of the multiplication term 'I'i@Kp*·KTA by the KMe method in step 14 is executed.

Thus, the value of the multiplication term Ti・Kp^・1 (TA calculated in steps 6 and 14 is expressed by the above equation (1).
In addition, the injection time 'I' of the fuel injection valve lO is calculated by applying other correction coefficients shown in the above formula (2).
OUT (step 15), and the program ends.

Note that the present invention is not limited to the fuel injection amount control of the above-mentioned fuel injection control device, but can be applied to various operation control means, such as an ignition timing control device, as long as the control of the operating characteristic quantity is performed in relation to the intake air amount. , exhaust recirculation control device, etc.

As detailed above, according to the method for controlling the operating characteristic quantity of the internal combustion engine operation control means of the present invention, when a transition of the engine from a state other than the predetermined low-load operating state to the predetermined low-load operating state is detected, The second operating characteristic quantity control value, which can be assumed to be the first and second operating characteristic quantity control values, respectively, based on both the first and second detected engine operating parameter values representing the load state of the engine is set to the first operating characteristic quantity control value. The operating characteristic quantity control value is determined based on the second detected engine operating parameter value until the operating characteristic quantity control value substantially matches the operating characteristic quantity control value, and thereafter the operating characteristic quantity control value is operated based on the first engine operating parameter detected value. A characteristic quantity control value is determined, and the operating characteristic quantity of the operation control means is controlled to the thus determined operating characteristic quantity control value, so that the engine operates smoothly and stably during low load operation such as idling operation. The operation can be made as follows.

[Brief explanation of the drawing]

Fig. 1 is a diagram illustrating the problems of the prior art that occur when switching the fuel injection amount control from the SD method to the KMe method during low-load engine operation, and Fig. 2 is a diagram showing fuel injection control to which the present invention is applied. The overall configuration diagram of the device, Figure 3 is a circuit diagram showing the internal configuration of the electronic control unit (ECU) in Figure 2,
FIG. 4 is a program flowchart showing a procedure for calculating the fuel injection time TOUT executed in the ECU, and FIG. 5 is a diagram showing various aspects of changes in engine operation. DESCRIPTION OF SYMBOLS 1... Internal combustion engine, 3... Intake passage, 5... Electronic control unit, (ECU), 9... Throttle valve, 10... Fuel injection valve, 12... Intake road absolute pressure Sensor, 14... Engine rotation angle position sensor: 17... Throttle valve sensor. Applicant Honda Motor Co., Ltd. Agent Patent Attorney Toshihiko Watanabe

Claims (1)

[Scope of Claims] 1. In an operating characteristic quantity control method for electronically controlling an operating characteristic quantity of an operation control means of an internal combustion engine, a predetermined low load operating state of the engine is detected, and the engine is in the predetermined low load operating state. , when the engine is at the predetermined low When the engine is in a state other than a load operating state, a second engine operating parameter value representing the engine load state is detected, and a control value of the operating characteristic quantity is determined based on the detected second engine operating parameter value. , when it is detected that the engine has transitioned from a state other than the predetermined low load operating state to the predetermined low load operating state, the first and second engine operating parameter detection values are determined based on both the first and second detected engine operating parameter values. Until the second operating characteristic quantity control value for which the second operating characteristic quantity control value has been requested substantially matches the first operating characteristic quantity control value, the second operating characteristic quantity control value is used. 1. A method for controlling an operating characteristic quantity of an internal combustion engine operation control means, characterized in that the operating characteristic quantity control value of an internal combustion engine is determined, and the operation characteristic quantity of the operation control means is controlled to the thus determined operating characteristic quantity control value. 2. The second operating characteristic quantity control value that is detected when the transition to a predetermined low-load operating state of the engine is detected crosses a value that substantially matches the first operating characteristic quantity control value and becomes a smaller value. When the operating characteristic quantity of the internal combustion engine operation control means according to claim 1 is determined, the control value of the operating characteristic quantity is determined based on the detected value of the first engine operating parameter. Control method. 3. The second operating characteristic quantity control value, which is detected when the transition to the B constant low load operating state of the engine is detected, is larger than a value that substantially matches the first operating characteristic quantity control value. The operation of the internal combustion engine operation control means according to claim 1, wherein the control value of the operating characteristic quantity is determined based on the detected value of the first engine operating parameter when the detected value of the engine operating parameter is reached. Characteristic quantity control method. 4. After detecting the transition of the engine to a predetermined low load operating state, determining the control value of the operating characteristic based on the detected value of the first engine operating parameter, and then changing the predetermined low load of the engine. Claims 1 to 3 are characterized in that the determination of the operating characteristic quantity control value based on the detected value of the first engine operating parameter is continued until a state other than the operating state is detected. 5. The method for controlling an operating characteristic quantity of an operation control means for an internal combustion engine according to any one of 5. The internal combustion engine includes an intake passage and an intake air amount control means for controlling an intake air amount by adjusting an opening area of the passage. The internal combustion engine according to any one of claims 1 to 4, wherein the first engine operating parameter includes an opening area of an intake passage adjusted by the intake air amount control means. 6. The internal combustion engine includes an intake passage and a throttle valve disposed in the middle of the passage, and the second engine operating parameter is determined by the throttle valve in the intake passage. 5. A method for controlling an operating characteristic quantity of an internal combustion engine operation control means according to any one of claims 1 to 4, characterized in that the method includes downstream pressure and engine rotational speed.