JPS63280831A - Fuel injection quantity controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the controllability of an air-fuel ratio by having an injection quantity controlled respectively on the basis of the opening of a throttle valve and the rotational speed of an engine when the opening of a sub control valve inside a sub suction air passage bypassing the throttle valve is below a predetermined value, and on the basis of a real suction air amount and the rotational speed of the engine when it is above the predetermined value. CONSTITUTION:At a main suction air passage provided with a throttle valve 8, a bypass 14 which functions as a sub suction air passage is connected so as to bypass the throttle valve 8, and an ISC valve (sub control valve) whose drive source is a pulse motor is provided on its way. And during the operation of an engine, whether the opening of the ISC valve 16 surpasses a predetermined value or not is decided at a control circuit 44, and when decided that it is below the predetermined value, a basis fuel injection time is operated on the basis of the output of a throttle valve opening sensor 10 and the rotational speed of tan engine sought at a rotational angle sensor 48. Meanwhile, when it has been decided that the opening of the ISC valve 16 surpasses the predetermined value, it is so arranged that the basic fuel injection time is operated on the basis of the output of a suction air pipe pressure sensor 6 and the rotational speed of the engine.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel injection amount control device for an internal combustion engine, and particularly relates to a fuel injection amount control device for an internal combustion engine. The sub-m'l that controls the amount of air flowing into the sub-intake passage that communicates with the sub-m'l? The present invention relates to a control device that controls the fuel injection amount of an internal combustion engine equipped with eleven valves.

[Prior Art] Conventionally, the upstream side of the main intake passage in which the throttle valve is disposed and the throttle valve 'tN (il, l+
An internal combustion engine is known in which an auxiliary intake passage is provided so as to communicate with the auxiliary intake passage, and an auxiliary control valve (hereinafter referred to as an ISC valve) that controls the amount of air flowing through the auxiliary intake passage is attached to the auxiliary intake passage. In this internal combustion engine, the opening degree of the ISC valve is controlled during idling so that the engine rotational speed becomes the target rotational speed. Here, when the air conditioner is operating, when the engine cooling water temperature is low,
The shift lever of the automatic transmission is in the drive range (D range, R range).
When the engine is in a range (range, etc.), the target rotational speed is set high to prevent engine stall. Since the target rotational speed is increased in this manner, the opening degree of the ISC valve becomes larger and the amount of air flowing into the sub-intake passage increases. When the vehicle is running, the opening degree of the ISC valve controlled during idle link is maintained.

On the other hand, in an electronically controlled internal combustion engine, the throttle opening and engine rotational speed are detected, the basic fuel injection time is calculated based on the detected throttle opening and engine rotational speed, and the basic fuel injection The amount of fuel injection is controlled by correcting the time using intake air temperature, engine cooling water temperature, etc., and opening the fuel injection valve for a time corresponding to the corrected time.

That is, JP-A-59-196949 and JP-A-60-122237 disclose that the basic fuel injection time is calculated based on the throttle opening degree and the engine rotational speed to control the fuel injection amount. It has been published in Japanese Patent Publication No. 59-399.
No. 48 discloses that the intake pipe pressure is calculated based on the throttle opening degree and the engine rotation speed, and the basic fuel injection time is calculated based on the calculated intake pipe pressure and the engine rotation speed to control the fuel injection amount. Disclosed. Incidentally, as a technique related to the present invention, there is a technique described in Japanese Patent Application Laid-Open No. 60-224951.

[Problem that the invention seeks to solve]

However, if the fuel injection amount is controlled based on the throttle opening and engine speed in an internal combustion engine equipped with the above-mentioned auxiliary intake passage, the throttle opening corresponds to the amount of air passing around the throttle valve. If the amount of air flowing into the auxiliary intake passage is large, the amount of air detected from the throttle opening will show a value smaller than the actual amount of intake air taken into the engine combustion chamber. Figure 2 (1) shows the intake pipe pressure PM relative to the throttle opening TA when the engine speed is constant.
It shows the change in the intake pipe pressure P corresponding to the actual intake air amount when the throttle opening is small, that is, in the light load range.
M is getting bigger. For this reason, if the fuel injection amount is controlled based on the throttle opening and engine speed, the air-fuel ratio will be controlled to be leaner than the target air-fuel ratio due to the influence of the air flowing into the auxiliary intake passage, resulting in poor exhaust emissions and drivability. There is a problem. In particular, when the engine is cold, the opening degree of the ISC valve is large, so the deviation of the air-fuel ratio from the target air-fuel ratio becomes large.

The present invention has been made to solve the above-mentioned problems, and in an internal combustion engine that controls the fuel injection amount based on the throttle opening degree and engine rotation speed, the air-fuel ratio is adjusted to the target air-fuel ratio due to the influence of the amount of air flowing into the auxiliary intake passage. It is an object of the present invention to provide a fuel injection amount control device for an internal combustion engine that prevents deviations in the air-fuel ratio due to the amount of air flowing into the sub-intake passage by controlling the fuel injection amount based on the actual intake air amount when the fuel ratio deviates from the fuel ratio. purpose.

[Means for solving problems]

In order to achieve the above object, the present invention includes a sub-control valve that controls the amount of air flowing into a sub-intake passage that communicates between the upstream side of the main intake passage in which the throttle valve is disposed and the downstream side of the throttle valve. A fuel injection amount control device for an internal combustion engine that controls a fuel injection amount of an internal combustion engine includes a throttle opening detection means for detecting a throttle opening, a rotation speed detection means for detecting an engine rotation speed, and a rotation speed detection means for detecting an engine rotation speed. a physical quantity detection means for detecting a physical quantity corresponding to the actual amount of intake air taken in; a throttle opening detected when the opening of the sub-control valve is less than a predetermined opening; and a detected engine rotational speed. The fuel injection amount is controlled based on the physical quantity detected when the opening degree of the sub-control valve exceeds the predetermined opening degree, and the detected engine rotation speed. A control means is provided.

[Effect]

According to the present invention, the fuel injection amount is controlled based on the throttle opening and engine speed when the opening of the sub-control valve is below a predetermined opening, and when the opening of the sub-control valve exceeds the predetermined opening. The fuel injection amount is controlled based on the physical quantity corresponding to the actual intake air amount taken into the engine combustion chamber and the engine rotation speed. As the physical quantity corresponding to the actual intake air amount taken into the engine combustion chamber, the intake pipe absolute pressure on the downstream side of the throttle valve and the air amount on the upstream side of the throttle valve can be adopted. In this way, the fuel injection amount can be controlled based on the actual intake air amount when the opening degree of the sub-control valve exceeds the predetermined opening degree, so even if the amount of air flowing into the sub-intake passage is large, the fuel injection amount can be controlled based on the actual intake air amount. The air-fuel ratio can be controlled to the target air-fuel ratio.

〔Effect of the invention〕

As explained above, according to the present invention, when the air-fuel ratio varies depending on the amount of air flowing into the auxiliary intake passage, the fuel injection amount is controlled based on the actual intake air amount. The effect is that the air-fuel ratio can be controlled to the target air-fuel ratio without being influenced by the air-fuel ratio, thereby improving exhaust emissions and drivability.

[Explanation of aspects]

In carrying out the present invention, the following embodiments may be adopted.

In a first aspect, the fuel injection amount is controlled by the fuel injection amount control means based on the throttle opening detected when the engine cooling water temperature is below a predetermined temperature and the detected engine rotational speed, and the engine cooling The fuel injection amount is controlled based on the physical quantity detected when the water temperature exceeds the predetermined temperature and the detected engine rotation speed.

In an internal combustion engine equipped with an auxiliary control valve that controls the amount of air flowing into the auxiliary intake passage, when the engine cooling water temperature is low, the viscosity of the engine oil increases, causing the piston's a! Low friction resistance may increase and engine stall may occur during idling, so when the engine cooling water temperature is low, the opening of the sub-control valve is increased to increase the amount of air flowing into the sub-intake passage, thereby increasing the idle rotation speed. are doing. Therefore, when the engine cooling water temperature is below the predetermined temperature, the opening degree of the sub-control valve will exceed the predetermined opening degree. Therefore, in the first aspect, the opening degree of the sub-control valve is predicted from the engine cooling water temperature and the control of the fuel injection amount is switched.

Further, in a second aspect, the fuel injection amount is controlled by the fuel injection amount control means based on the throttle opening detected when the air-fuel ratio feedback condition is satisfied and the detected engine rotational speed, and the air-fuel ratio is controlled. The fuel injection amount is controlled based on the detected physical quantity and the detected engine rotational speed when the feedback condition is not satisfied.

Equipped with a sub-control valve that controls the amount of air flowing into the sub-intake passage,
In an internal combustion engine, an air-fuel ratio feedback correction coefficient is determined based on the output of the 02 sensor that detects the residual oxygen concentration in exhaust gas, and the fuel injection amount is controlled based on the basic fuel injection time and the air-fuel ratio feedback correction coefficient. When the amount of air flowing through the passage increases and the air-fuel ratio becomes lean, the second
As shown in Figure (2), the air-fuel ratio feedback correction coefficient F
AF increases, and as a result, the air-fuel ratio is controlled to the target air-fuel ratio. Therefore, even if the amount of air flowing into the auxiliary intake passage is large, the air-fuel ratio will not deviate from the target air-fuel ratio due to the amount of air flowing into the auxiliary intake passage during air-fuel ratio feedback control. On the other hand, when air-fuel ratio feedback control is not performed, if the amount of air flowing into the auxiliary intake passage is large, the throttle opening and the actual amount of intake air will not match, especially at light loads, as explained in Fig. 2 (1). As shown in Figure 2 (3), the air-fuel ratio becomes the target air-fuel ratio (for example, the stoichiometric air-fuel ratio).
This will cause the parts to shift. Therefore, in the second aspect, it is determined that there is a possibility that the air-fuel ratio deviates from the target air-fuel ratio during air-fuel ratio open loop control, and when air-fuel ratio feedback control is not performed, a physical quantity corresponding to the actual intake air amount is determined. The fuel injection amount is controlled based on the output of the physical quantity detecting means for detecting. Note that when air-fuel ratio feedback control is not performed and the opening degree of the sub-control valve is below a predetermined value, the air-fuel ratio does not deviate from the target air-fuel ratio. The fuel injection amount may be controlled based on the physical quantity detected when the opening degree of the engine exceeds a predetermined opening degree and the detected engine rotation speed.

Further, the present invention can adopt the embodiments described below when controlling the fuel injection amount based on the throttle opening degree and the engine rotation speed. These aspects will be explained below. Normally, the throttle valve is located upstream, away from the engine combustion chamber, and there is a time delay before the air passing through the throttle valve reaches the engine combustion chamber, and there is also a gap between the throttle valve and the intake valve. Because of the volume, the throttle opening will advance in phase with respect to changes in the actual intake air amount. Therefore, the intake pipe pressure P determined by the throttle opening and engine speed
As shown in FIG. 3, (TA, NE) is a value whose phase is advanced from the actual intake pipe pressure P.

Note that PM is the intake pipe pressure obtained from a pressure sensor placed downstream of the throttle valve. In addition, as shown in Figure 4, the basic fuel injection amount TP (TA, NE) determined by the throttle opening and engine rotational speed is such that changes in the throttle opening are out of phase with respect to changes in the actual intake air amount. Since the amount of fuel is increasing, the amount of fuel to be injected will be greater than the required amount. For this reason, if the fuel injection amount is controlled based on the throttle opening and engine speed, the fuel injection amount will be greater than the required value during acceleration, resulting in an overrich air-fuel ratio, and the fuel injection amount will be less than the required value during deceleration. This causes the air-fuel ratio to become over-lean. Further, even when the acceleration increase correction is performed, the increase value becomes as shown by diagonal lines in FIG. 4, and the above-mentioned phase advance cannot be corrected.

Therefore, in the third case B, when the fuel injection amount control means controls the fuel injection amount when the opening of the sub-control valve is less than the predetermined opening, the fuel injection amount is controlled based on the throttle opening and the engine rotation speed. Calculate the intake pipe pressure using the time elapsed from the time of throttle opening change as a variable, calculate the basic fuel injection time based on the calculated intake pipe pressure and engine rotational speed, and calculate the basic fuel injection time based on the calculated intake pipe pressure and engine rotation speed. Based on this, the fuel injection amount is controlled.

The principle of the third aspect will be explained below. As shown in Fig. 5, considering the intake system from the throttle valve Th through the surge tank S to the intake valve of engine E, the air pressure in the intake system (intake pipe absolute pressure) is P [anHgabs, ]
, the volume of the intake system is V[N, the weight of the air in the intake system is Q[gl, and the absolute temperature of the air in the intake system is T[”
K], atmospheric pressure is Pc[mHgabs, ], and
The weight of air per unit time taken into the combustion chamber of engine E from the intake system is ΔQ+ [g/sec], and the weight of air per unit time taken into the intake system after passing through the throttle valve Th is ΔQz [g /sec], and the weight of the air in the intake system changes by (ΔQ2-ΔQ,)・ΔL within a minute time Δ, and at this time, the pressure of the air in the intake system changes by ΔP. When the Boyle-Charles law is applied to , the following equation (1) is obtained.

(P+Δp)v- (Q+(ΔQ2-ΔQ,)Δt) RT...
(1) However, R is a gas constant.

On the other hand, since PV=Q-R-T, if the above (1) 2 is modified, the following equation (2) is obtained.

Here, if the flow coefficient is ψ and the opening area of the throttle valve (throttle opening) is A, the air weight ΔQ2 per unit time passing through the throttle valve is expressed by the following equation (3), and the stroke volume is V3. , the engine rotational speed is NE [rpm], and the intake efficiency is η, then the air weight ΔQ per unit time sucked into the combustion chamber of the engine is expressed by the following equation (4).

ΔQ2-ψ・A1pi]-]Y...(3) Above (3)
, by substituting equation (4) into equation (2), the following equation (5) is obtained.

Here, if we take the limit of ΔL→0, we get becomes.

Now, considering the response near pressure P, (≠Pc), the pressure is P. Assuming that P and +P have changed from P to +P, P in place of P in the above formula (6). By substituting 10P (where P is a minute value), the following equation (7) is obtained.

...(7) Here, ...(8) Therefore, the above equation (7) becomes like the following equation (9) 2 v 60 ...(9) Here, t above 0 Transform the equation as shown below and integrate both sides,
When the integral constant is C, the following formula 04 is obtained.

--I! , Og (-a P+b) =
L + c - cm where 1=0, P
Since the initial value of is P, the integral constant C is obtained from the above equation 04 as follows.

C=-1ogc-aP+b) -05) P is calculated from the above 0 expression and θ expression as follows.

a a However, e is the base of natural logarithm.

Therefore, by measuring the opening area A of the throttle valve, that is, the throttle opening TA, the engine speed NE, and the elapsed time t from the time when the throttle opening changes, and substituting them into the above equation 00, the actual intake pipe pressure P can be found. Can be done. Then, based on the actual intake pipe pressure P and engine speed NE obtained in this way, the basic fuel injection time TP is obtained by calculating, for example, the following formula, and this basic fuel injection time TP is The fuel injection time is determined by correcting it according to the air temperature, engine cooling water temperature, etc., and by opening the fuel injection valve for a time corresponding to this fuel injection time, the engine starts when the opening degree of the sub-control valve is below a predetermined value. The required amount of fuel can be injected.

TP=ni-F/NE However, K is a constant.

By the way, if the intake pipe pressure P of the above 0e formula is expressed in a graph, it will be as shown in Fig. 6, where 1=0, P=Pa, t→ω
In the limit (steady state), it is the output of the first-order lag element that becomes P = b / a (intake pipe pressure PMTA in steady state). Therefore, throttle opening TA and engine rotation speed NE
The intake pipe pressure PMTA in a steady state is calculated based on The actual intake pipe pressure may be calculated by

Also, S is a Laplace transform operator, and T is a time constant.

That is, in the third aspect, the intake pipe pressure in a steady state is calculated based on the throttle opening degree and the engine rotation speed,
The intake pipe pressure may be calculated using the elapsed time as a variable by processing the calculated intake pipe pressure in a steady state using a first-order lag element.

As explained above, according to this aspect, the actual intake pipe pressure is predicted when the opening degree of the sub-control valve is below a predetermined value, and the fuel injection amount is controlled based on this intake pipe pressure and the engine rotation speed. Therefore, when the opening degree of the sub-control valve is less than the predetermined opening degree, fuel can be injected in an amount corresponding to the actual amount of intake air.This allows the air-fuel ratio to be controlled to the target air-fuel ratio during transient periods. This has the effect of preventing over-rich and over-lean air-fuel ratios.

Furthermore, a fourth aspect provides an internal combustion engine equipped with a sub-control valve that controls the amount of air flowing into a sub-intake passage that communicates between the upstream side of the main intake passage in which the throttle valve is disposed and the downstream side of the throttle valve. A fuel injection amount control device for an internal combustion engine that controls a fuel injection amount includes a throttle opening detection means for detecting a throttle opening, a rotation speed detection means for detecting an engine rotation speed, and a rotation speed detection means for detecting an engine rotation speed. an intake pipe pressure calculation means for calculating intake pipe pressure in a steady state based on the engine rotation speed, and correction for a response delay of the intake pipe pressure during a transient period with respect to the calculated intake pipe pressure in the steady state. a physical quantity detection means for detecting a physical quantity corresponding to the actual intake air amount taken into the engine combustion chamber; and a physical quantity detection means for detecting a physical quantity corresponding to the actual amount of intake air taken into the engine combustion chamber; The basic fuel injection time is calculated based on the pipe pressure and the detected engine rotation speed, and when the opening degree of the sub-control valve exceeds the predetermined opening degree, it is based on the detected physical quantity and the detected engine rotation speed. basic fuel injection time calculation means for calculating the basic fuel injection time;
The fuel injection amount control means controls the fuel injection amount based on the basic fuel injection time.

To explain the control of the fuel injection amount when the opening degree of the sub-control valve in this aspect is below a predetermined opening degree, as shown in the block diagram shown in FIG. 8, the throttle opening degree TA detected by the throttle opening degree detection means The intake pipe pressure PMTA in a steady state is calculated by the intake pipe pressure calculation means A based on the engine rotation speed NE detected by the rotation speed detection means. The intake pipe pressure PMTA in a steady state calculated by the intake pipe pressure calculation means A is corrected by the correction means for the response delay of the intake pipe pressure during a transient period. A first-order lag element can be used as this correction means. The intake pipe pressure corrected by the correction means B is input to the basic fuel injection time calculation means C, and the basic fuel injection time TP is calculated based on the engine rotational speed NE input to the basic fuel injection time calculation means. . On the other hand, when the opening degree of the sub-control valve exceeds the predetermined opening degree, the basic fuel injection time TP is calculated based on the physical quantity corresponding to the actual intake air amount, such as the intake pipe pressure or the intake air amount, and the engine rotational speed NE. Ru. and,
The fuel injection amount is controlled by the fuel injection amount control means based on the basic fuel injection time TP.

Further, in a fifth aspect, when calculating the basic fuel injection time when the opening degree of the sub-control valve is equal to or less than a predetermined opening degree by the basic fuel injection time calculation means in the fourth aspect, the throttle opening degree and the engine rotation The intake pipe pressure in a steady state is calculated at a predetermined period based on the speed, and a weighting coefficient is calculated based on the time constant regarding changes in intake pipe pressure during transient periods and the predetermined period, and a weighted average calculated in the past is calculated. A current weighted average value is calculated using the weighted average value calculated in the past by increasing the weight of the value, the intake pipe pressure in the steady state, and the coefficient related to the weight, and the calculated current weighted average value and the engine are calculated. The basic fuel injection time is calculated based on the rotational speed, and the fuel injection amount is controlled based on the calculated basic fuel injection time.

Next, the principle of this embodiment will be explained. The block diagram of the first-order lag element is shown in Figure 7, where the input is x(t
), the output is y(t), and the time constant is T, the relationship between the human outputs shown in FIG. 7 is expressed by the following equation.

...QI Here, if 1t is the current calculation timing and tl is the past calculation timing, the following equation (21) is obtained.

(tx t+) ・[x (tz) )'
(t+) ] + y (t+) = y (tz)
...(21) In the above (21), x (tg)
is the intake pipe pressure P M T A , Y (
tz) as the current actual intake pipe pressure P M S M5,3
'(t+) is past actual intake pipe pressure PMSM+-+
, tz t+ (=Δt) is the operation period, then 1” + P M S M r −+ = P M S M
t (22), and if T/Δt=n, the following equation (23) is obtained.

...(23) In other words, the above equation (23) is a weighted average with the weight of the past actual intake pipe pressure PMSMi-, set as n-1, and the weight of the intake pipe pressure PMTA in the steady state set as 1. This shows that the current actual intake pipe pressure P M S M can be calculated by calculating the current actual intake pipe pressure P M S M . Further, the coefficient n regarding the weight is determined by the ratio of the time constant T and the calculation period Δt.

Therefore, the intake pipe pressure PMTA in a steady state is calculated at a predetermined period Δt based on the throttle opening degree and the engine rotational speed, and a coefficient related to the weighting is calculated using a time constant T regarding changes in intake pipe pressure during transient periods and a predetermined period Δt. Calculate the weighted average value PMSM5-1 calculated in the past by increasing the weight of the weighted average value PMSM=, which was calculated in the past, and the intake pipe pressure PMTA in the steady state and the coefficient n regarding the weight. Above (23)
By calculating the weighted average value PMSM according to the formula, the current actual intake pipe pressure can be determined. Therefore, in this aspect, based on the weighted average value (current actual intake pipe pressure) calculated as described above and the engine rotation speed, the basic fuel is The injection time is calculated, and the fuel injection amount is controlled based on the calculated basic fuel injection time when the opening degree of the sub-control valve is less than or equal to a predetermined opening degree.

Note that, as understood from the above equations 0ω and 00, the time constant T=I/a becomes smaller as the engine rotational speed NE becomes larger, and becomes smaller as the throttle opening TA becomes larger. In this way, the time constant is expressed by a function using the throttle opening degree TA and the engine rotational speed NE as variables. Therefore, if the calculation period Δt is constant, the weighting coefficient n can be determined by a function using the throttle opening TA and the engine rotational speed NE as variables. In addition, since the intake pipe pressure PMTA in the steady state is uniquely determined by the throttle opening TA and the engine rotation speed NE, the intake pipe pressure PMTA in the steady state can be used instead of the throttle opening TA and the engine rotation speed NE. The weighting coefficient n may be determined depending on the engine rotational speed NE.

Incidentally, the amount of air supplied to the engine combustion chamber is determined at the end of intake, that is, when the intake valve is closed. However, a predetermined time is required to calculate the fuel injection time, a predetermined flight time is required for the fuel injected from the fuel injection valve to reach the combustion chamber, and the amount of air supplied to the combustion chamber If the fuel injection amount is calculated when the amount of air is determined, there will be a time delay, so conventionally, the basic fuel injection time is calculated using the intake pipe pressure before the amount of air supplied to the combustion chamber is determined. For this reason, the amount of fuel that matches the amount of air actually taken into the combustion chamber is no longer injected, and during acceleration, the amount of fuel F4 injection is controlled by an intake pipe pressure that is smaller than the intake pipe pressure that determines the amount of intake air. Therefore, the air-fuel ratio becomes lean, and during deceleration, the fuel injection amount is controlled by an intake pipe pressure that is larger than the intake pipe pressure that determines the intake air amount, so the air-fuel ratio becomes rich.

On the other hand, in the above equation (23), assuming that the throttle opening degree TA and the engine rotational speed NE do not change, the predetermined period from the weighted average value calculation until the intake air amount is determined, that is, from the weighted average value calculation to the predetermined The intake pipe pressure PMTA in the steady state is constant up to a certain time. Therefore, the above (
23) By repeatedly calculating the weighted average value of the equation, the actual intake pipe pressure of the intake air 1611 at a fixed time can be predicted.

Therefore, in this aspect, when the opening degree of the sub-control is below the predetermined opening degree, the calculation period Δ
By dividing by t, the number of calculations is obtained, and by repeating the calculation of the weighted average of the above formula (23) for this number of calculations, the weighted average value at the time when the amount of air sucked into the engine is determined, that is, the amount of air sucked into the engine. It is preferable to control the fuel injection amount by predicting the actual intake pipe pressure at the time when the amount of air to be injected is determined.

Note that the above assumes that the throttle opening and engine rotational speed do not change from the time the fuel injection time is calculated until the amount of air taken into the engine is determined, but the throttle opening and engine rotational speed may change. In this case, the differential value of the throttle opening and/or the differential value of the engine rotational speed at the time of calculating the fuel injection time is used to predict the throttle opening and/or the engine rotational speed at the time of the next fuel injection time calculation. hand,
If you predict the intake pipe pressure in a steady state when the intake air amount is determined, and then repeat the calculation of the weighted average value as described above to predict the actual intake pipe pressure, it will be possible to predict the actual intake pipe pressure when the throttle opening or engine speed fluctuates. The accuracy of the predicted value of the actual intake pipe pressure is further improved.

In addition, the fuel injected from the fuel injection valve adheres to the engine wall surface such as the inner wall surface of the intake manifold, and not all of the injected fuel is supplied to the combustion chamber, so this amount of fuel adhesion is corrected to adjust the fuel injection amount. Preferably controlled. This amount of fuel adhesion depends on the magnitude of the intake pipe pressure; when the intake pipe pressure is low, the amount of fuel evaporation increases, so the amount of fuel adhesion decreases, and when the intake pipe pressure is high, the amount of fuel evaporation decreases. Therefore, the amount of fuel deposited increases. Therefore, in this aspect,
When the opening of the sub-control valve is below a predetermined opening, the amount of change in the amount of fuel adhering to the engine wall is predicted from the actual intake pipe pressure calculated by weighted average, and the amount of fuel that is equivalent to this amount of change is calculated. It is preferable to correct the injection amount to supply the engine with an amount of fuel corresponding to the actual amount of intake air taken into the engine. Note that the amount of fuel adhering to the wall surface also changes depending on the engine temperature and engine rotation speed (the higher the engine temperature, the greater the amount of fuel evaporation, so the amount of fuel adhesion decreases, and the faster the engine rotation speed increases the air flow velocity). Therefore, the amount of change in fuel adhesion may be determined as a function of engine temperature and engine rotation speed, and the amount of fuel adhesion on the wall surface may be determined as a function of engine temperature and engine rotation speed. Since this does not stabilize instantaneously, the correction amount of the fuel injection amount may be attenuated over time so that the amount of fuel deposited during the current injection is reflected in subsequent injections.

As explained above, in this aspect, the actual intake pipe pressure is predicted by calculating the weighted average value at a predetermined period when the sub-control valve opening is less than a predetermined opening. The actual intake pipe pressure can be predicted without measuring the elapsed time, and this allows the air-fuel ratio to be controlled to the target air-fuel ratio even during transient periods, preventing deterioration in acceleration response, drivability, exhaust emissions, etc. This has the effect of being able to prevent this.

Incidentally, in Mr. B above, an example was explained in which the basic fuel injection time is calculated based on the amount corresponding to the intake pipe pressure and the engine rotation speed when the opening degree of the sub-control valve is less than the predetermined opening degree. The basic fuel injection time may be calculated based on the amount corresponding to the amount of air passing upstream of the throttle valve and the engine rotation speed.

〔Example] Embodiments of the present invention will be described in detail below with reference to concave surfaces.

FIG. 9 is a schematic diagram of an internal combustion engine equipped with the fuel injection amount control device of this embodiment.

A throttle valve 8 is located downstream of the air cleaner (not shown).
is located. A throttle opening sensor 10 for detecting the opening of the throttle valve 8 is attached to the throttle valve 8 . The throttle opening sensor 10 is the 10th
As shown in the equivalent circuit in the figure, it is composed of a contactor 10B fixed to the rotary wheel of the throttle valve 8 and a variable resistor 10A connected to a power source at one end and grounded at the other end. As the opening degree changes, the contact 10B
The contact state between the variable resistor 10A and the variable resistor 10A changes, and a voltage corresponding to the opening degree of the throttle valve 8 is obtained from the contactor 10B. A temperature sensor 14 comprised of a thermistor is attached to the intake pipe wall upstream of the throttle valve 8 to detect the temperature of intake air. Throttle valve 8
A surge tank 12 is arranged on the downstream side. This surge tank 12 has a pressure sensor 6 on the second diaphragm.
is installed. The output signal from the pressure sensor 6 is filtered by a filter 7 (see FIG. 11), which is constructed of a CR filter or the like with a small time constant (for example, 3 to 5 m5ec) and good responsiveness to remove the pulsating component of the intake pipe pressure. reference). Further, a bypass passage 14 as a sub-intake passage is provided so as to bypass the throttle valve and communicate the upstream side of the throttle valve with the downstream side of the throttle valve.

An ISC pulp 16 is attached to the bypass path 14, which is composed of a pulse motor 16A having a four-pole stator and a valve body whose opening degree is controlled by the pulse motor. Note that an ISC valve that controls the amount of air flowing into the bypass path by controlling the duty ratio, or one that includes a thermowax and controls the amount of air flowing into the bypass path depending on the temperature may be used. The surge tank 12 is communicated with a combustion chamber 25 of the engine body 20 via an intake manifold 18, an intake port 22, and an intake valve 23. A fuel injection valve 24 is attached to this intake manifold 24 so as to correspond to each cylinder, and is configured to be able to inject fuel to each cylinder independently, to each cylinder group, or to all cylinders simultaneously. .

The combustion chamber 25 is communicated with a catalyst device (not shown) filled with a three-way catalyst via an exhaust valve 27, an exhaust boat 26, and an exhaust manifold 28. The exhaust manifold 28 detects the residual oxygen concentration in the exhaust gas and outputs a signal that is inverted at a value corresponding to the stoichiometric air-fuel ratio. 2 sensors 30 are attached.

A cooling water temperature sensor 34 made of a thermistor or the like is attached to the cylinder block 32 so as to protrude into the water jacket and detects the engine cooling water temperature representative of the engine temperature. A spark plug 38 is attached to the cylinder head 36 so as to protrude into each combustion chamber 25 . The spark plug 3 is connected to a control circuit 44 made up of a microcomputer or the like via a distributor 40 and an igniter 42 equipped with an ignition coil. A cylinder discrimination sensor 46 and a rotation angle sensor 48 are attached to the distributor 40, each of which includes a solenoid rotor fixed to the distributor shaft and a pickup fixed to the distributor housing.

The cylinder discrimination sensor 46 outputs a cylinder discrimination signal, for example, every 720'CA, and the rotation angle sensor 48 outputs a cylinder discrimination signal, for example, every 30'CA.
A rotation angle signal is output for each A. Then, the engine rotation speed can be calculated from the period of this rotation angle signal.

A control circuit 44 composed of a microcomputer etc.
As shown in FIG. 11, a microprocessing unit (MPU) 60, a read-only memory (ROM)
62, random access memory (RAM) 64, backup RAM (BU-RAM) 66, input/output capotro 8, input port door 0, output port door 2.74.76, and data bus, control bus, etc. that connect these. It is equipped with bus 75. An analog-to-digital (A/D) converter 78 and a multiplexer 80 are connected in sequence to the input/output capotro 8.
0 is connected to the intake temperature sensor 14 via a buffer 82, and to the water temperature sensor 34 and the throttle opening sensor 10 via buffers 84 and 85, respectively. Further, the pressure sensor 6 is connected to the multiplexer 80 via a buffer 83 and a CR filter 7 composed of a resistor R and a capacitor C. The input/output capotro 8 is connected to the A/D converter 7 and the multiplexer 80, and outputs the intake air temperature sensor 14 and the CR filter 7 according to the control signal from the MPU.
Pressure sensor 6 output, water temperature sensor 34 manually operated via
The output and the throttle opening sensor 10 output are controlled to be A/D converted sequentially at a predetermined period.

The input port door 0 is connected to the 02 sensor 30 via a comparator 88 and a buffer 86, and also to the cylinder discrimination sensor 46 and the rotation angle sensor 48 via a waveform shaping circuit 90.

The output port door 2 is connected to the igniter 42 via a drive circuit 92, the output port door 4 is connected to the fuel injection valve 24 via a drive circuit 94, and the output port door 6 is connected to the ISC pulp via a drive circuit 96. It is connected to the pulse motor 16A.

Next, a first embodiment in which the second aspect and the fifth aspect are applied to the internal combustion engine will be described. The ROM 62 stores the intake pipe pressure in a steady state determined by the control routine program of the first embodiment of the present invention described below and the throttle opening TA and engine rotational speed NE shown in FIG. A map of PMTA, a map of the coefficient n related to the weight determined by the engine rotational speed NE and steady state intake pipe pressure PMTA (or throttle opening TA) shown in FIG. 13, and the actual intake air shown in FIG. A map of basic fuel injection time TP determined by pipe pressure PMSM and engine rotational speed NE is stored in advance. The map of intake pipe pressure PMTA in the steady state shown in FIG. 12 is based on the throttle opening T
It is created by setting A and engine rotational speed NE, measuring the intake pipe pressure corresponding to the set throttle opening TA and engine rotational speed NE, and using the value when the intake pipe pressure is stabilized. The map of the weight-related coefficient n shown in Fig. 13 is obtained by measuring the time constant T during the intake pipe pressure response (indicinal response) when the throttle valve is opened in steps, and is shown in Fig. 16 with this measured value. It is created by finding T/ΔL (:n) from the execution cycle Δt see of the f4X routine in correspondence with the engine rotational speed NE and the actual intake pipe pressure PMTA (or throttle opening TA). The basic fuel injection time TP map shown in FIG. 14 is created by setting the engine speed and intake pipe pressure and measuring the basic fuel injection time TP that provides the target air-fuel ratio.

First, the main routine of this embodiment will be explained with reference to FIG. First, in step 120, it is determined whether the opening degree of the ISO valve exceeds a predetermined value. IS
The opening degree of the C valve can be detected by counting the number of pulses of the pulse motor, but it can be detected by providing a switch that turns on when the opening degree of the ISO pulp exceeds a predetermined value and a sensor that detects the opening degree of the ISC valve. It's okay. When it is determined in step 120 that the ISO valve spacing is less than or equal to a predetermined value, a basic fuel injection time TP is calculated in step 128 based on the throttle opening TA and the engine rotational speed NE. Note that this basic fuel injection time TPO calculation will be explained based on the subroutine shown in FIG. 16. On the other hand, when it is determined in step 120 that the ISC pulp opening exceeds the predetermined value, in step 122 the intake pipe pressure PM and engine speed NE detected by the pressure sensor 6 are taken in, and in step 124 the basic fuel Calculate injection time TP. In the next step 126, the basic fuel injection time TP, the air-fuel ratio feedback correction coefficient FAF calculated in the routine of FIG. 15, and the correction coefficient F determined by the intake temperature, engine cooling water temperature, etc.
The fuel injection time TALI is calculated using the following 2.

Next, a routine for calculating the air-fuel ratio feedback correction coefficient FAF for feedback-controlling the air-fuel ratio will be described with reference to FIG. 15.

First, in step 180, it is determined whether the air-fuel ratio feedback condition is satisfied. Whether or not the air-fuel ratio feedback condition is satisfied is determined depending on the operating state. For example, if the engine is not starting, the engine cooling water temperature is above a predetermined value (e.g., 40'C), and the fuel is being cut. Therefore, it is determined that the air-fuel ratio feedback condition is satisfied when the fuel is not being increased and the air-fuel ratio lean control is not being performed.

When it is determined in step 180 that the air-fuel ratio feedback condition is not satisfied, the air-fuel ratio feedback correction coefficient FAF is set to 1.0 in step 182, and then in step 198, the air-fuel ratio feedback correction coefficient FAF is stored in a predetermined area of the RAM. Remember.

On the other hand, when it is determined in step 180 that the air-fuel ratio feedback condition is satisfied, it is determined in step 184 whether or not the 02 sensor output indicates an air-fuel ratio rich state. When it is determined that the o2 sensor output indicates a rich air-fuel ratio, an integral constant KL is calculated from the air-fuel ratio feedback correction coefficient FAF in step 186, and the 0□ sensor output is reversed from lean to rich in step 188. decide whether or not.

If the determination in step 188 is affirmative, the proportionality constant SL is subtracted from the air-fuel ratio feedback correction coefficient FAF in step 190.

On the other hand, if it is determined in step 184 that the 0□ sensor output indicates a lean air-fuel ratio, then in step 192 the air-fuel ratio feedback correction coefficient FAF is set to the integral constant K.
After adding R, it is determined in step 194 whether the 0□ sensor output has reversed from rich air-fuel ratio to lean. When it is determined in step 194 that the air-fuel ratio sensor output has reversed from rich to lean, in step 196 the proportional constant SR is added to the air-fuel ratio feedback correction coefficient FAF, and then in step 19
8, the air-fuel ratio feedback correction coefficient FAF is set to RA
It is stored in a predetermined area of M.

Next, details of step 128 in FIG. 1 will be explained with reference to the fuel injection time calculation routine shown in FIG. 16. This routine is executed every predetermined time (for example, 8 ssec). In step 100, the A/D converted throttle opening TA (for example, A/D converted every 8 aasec) and the engine rotation speed NE are taken, and the process is performed in step 1.
At 02, throttle opening TA is determined from the map in Figure 12.
The steady state intake pipe pressure P MTA corresponding to the engine rotational speed NE is calculated. In the next step 104, a first
A coefficient n related to the weight is calculated from the map shown in FIG.

In addition, when the map of the coefficient n regarding the weight is determined by the throttle opening degree and the engine rotational speed, the coefficient n regarding the weighting is calculated in step 104 using the throttle opening degree TA and the engine rotational speed NE taken in at step 100. You can do it like this. In the next step 106, the intake pipe pressure PMTA calculated in step 102, the coefficient n regarding the weight calculated in step 104, and the previous weighted average value PMSM calculated in step 106 during the previous execution of this routine.
In the 0th-order step 108, which calculates the current weighted average value PMSM according to the equation (23) explained above using Then, the basic fuel injection time TP is calculated from the map shown in FIG.

Then, in a control routine (not shown), when a predetermined crank angle is reached, the fuel injection valve is opened for a time corresponding to the fuel injection time TAU calculated above to perform fuel injection. As a result of the above control, when the amount of air flowing into the bypass passage is small, the fuel injection amount is controlled based on the basic fuel injection time TP calculated from the throttle opening TA and the engine rotational speed NE by the routine shown in FIG. When the amount of air flowing into the bypass path is large, the fuel injection amount is controlled based on the basic fuel injection time determined by the intake pipe pressure detected by the pressure sensor, that is, the physical quantity corresponding to the actual intake air amount, and the engine rotation speed. be done. Therefore, when the amount of air flowing through the bypass path is large, the fuel injection amount is controlled based on the physical quantity corresponding to the actual intake air amount, which prevents the air-fuel ratio from deviating from the target air-fuel ratio due to the amount of air flowing through the bypass path. Ru.

Next, a routine for calculating the ignition advance angle θ in the above embodiment will be explained with reference to FIG. 17. This routine is executed at every predetermined crank angle.

In addition, in FIG. 17, the same parts as in FIG. 16 are given the same reference numerals, and the description thereof will be omitted. In step 112, a basic ignition advance angle θIIASE is calculated using the weighted average value PMSM calculated this time and the engine rotational speed NE.

This basic ignition advance angle .theta.st may be calculated using an arithmetic expression, or a map may be created and calculated from this map in the same manner as the basic fuel injection time. Then, in the next step 114, the basic ignition advance angle θ1lAs
Ignition advance angle θ is determined by multiplying l by a correction coefficient TK determined by intake air temperature, engine cooling water temperature, etc. Then, in an ignition timing control routine (not shown), ignition is executed by turning off the igniter at the basic ignition advance angle θ.

Figures 18 (1) and (2) show a comparison of the change in the air-fuel ratio during acceleration when no acceleration increase is performed in the conventional case and the change in the air-fuel ratio in this embodiment, and also show the fuel injection amount. As can be understood from FIG. 18, which shows the difference between the weighted average value PMSM used in this embodiment and the conventionally detected intake pipe pressure PM, the air-fuel ratio of the conventional example causes a lean spike during acceleration. However, the air-fuel ratio in this example is approximately flat.

As explained above, in this embodiment, when the amount of air flowing into the bypass passage is small, the actual intake pipe pressure is predicted and the fuel injection amount and ignition timing are controlled, thereby achieving accurate fuel injection amount control and ignition timing. can be controlled.

Next, a second practical example in which the present invention is applied to the above-mentioned internal combustion engine will be explained. This example predicts the actual intake pipe pressure when the amount of intake air is determined (when the intake valve is fully closed) by repeating the calculation of the weighted average value a predetermined number of times when the amount of air flowing through the bypass passage is small. The fuel injection amount is controlled by intake pipe pressure. Note that fuel injection control when a large amount of air flows through the bypass passage is the same as in the first practical example, and therefore a description thereof will be omitted. FIG. 19 shows a routine that is executed at predetermined time intervals (all seconds in this embodiment) to calculate the predicted value PMSM2 of the intake pipe pressure when the intake air amount is determined. At step 200, the engine rotational speed NE is acquired, and the throttle opening degree TA is A/D converted to acquire the throttle opening degree TA. In step 202, the steady state intake pipe pressure PMTA corresponding to the engine rotational speed NE and throttle opening TA is calculated from the map shown in FIG. In the next step 204, a weighting coefficient n is calculated from the map shown in FIG. In the next step 206 and step 208,
The previously computed weighted average value PMSM+-+ stored in the register PMSM 1 is continuously read out from the RAM and the above (
23) Based on the formula, the current weighted average value P M S M,
is calculated, and in step 210 this weighted average value P
M S M is stored in register PMSMI.

In the next step 212, the time T from the current time to the predicted intake pipe pressure time is determined.

1IIsec is the calculation period ΔL (=
8msec), the number of operations TI/Δ
Calculate L. This predicted time T, m5ec can be the time from the current time until the intake air amount is determined, that is, the time from the current time until the intake valve closes.If fuel is not injected independently in each cylinder, the fuel injection valve It is determined by taking into account the flight time of the fuel from the current point to the combustion chamber, but even if the crank angle from the current moment to the predicted light is the same, this predicted time T1m5ec becomes shorter as the engine rotation speed increases, so the engine rotation speed It is preferable to vary the length depending on operating conditions such as (for example, shorten as the engine rotation speed increases). In the next step 214, the number of calculations TI/
The calculation of the above equation (23) is repeated for Δ times, and in step 216, the calculated value is set as the predicted value PMSM2 of the intake pipe pressure. By repeatedly executing the weighted average value in this way, the latest weighted average value approaches the intake pipe pressure value in the steady operating state, so by determining the number of times the weighted average value is calculated as described above, it is possible to , m5
It is possible to predict the intake pipe pressure ahead of EC (the intake pipe pressure in a state closer to a steady state than at the present time).

FIG. 20 shows a routine for calculating the fuel injection time TAU at every predetermined crank angle (for example, 120" CA), based on the engine rotational speed NE and the predicted value PMSM2 of the intake pipe pressure calculated in step 216. Then, the basic fuel injection time TP is calculated from the map shown in FIG.

Please note that the throttle opening and engine speed may change after T, m5ec has passed from the current time.
Using the differential value of the throttle opening and the differential value of the engine rotational speed, predict the throttle opening and engine rotational speed after T+ll5eC, predict the intake pipe pressure in the steady state after m5ec, and calculate the above. The accuracy can be further improved by repeating the calculation of the weighted average value.

The weighted average value and 'l' when calculated as above,
The predicted value PMSM2 after m5ec has elapsed is shown in FIGS. 21 and 22. In FIG. 21, the predicted value and the theoretical value for 16 m5 ec ahead are shown, and the predicted value is approximately equal to the theoretical value. Note that the A/D conversion timing of the throttle opening may differ from the fuel injection time fJ calculation timing, but there is a time difference corresponding to the maximum calculation cycle ΔL. Therefore,
Average this deviation time (0+Δt)/2 and get T, ±
The intake pipe pressure may be predicted for Δt/2 hours ahead.

Next, a third embodiment of the present invention will be described. In this embodiment, when the air-fuel ratio feedback condition is met, the amount of fuel deposited on the engine wall is predicted and the fuel injection amount is corrected. Note that in this embodiment, v! , including the calculation of the fuel injection time TAU.

The amount of fuel adhering to the engine wall without being sucked into the engine combustion chamber is determined by the intake pipe pressure when the intake valve is closed. For example, when the intake pipe pressure accelerates from PMI to PM2, Let T1 and T2 be the fuel adhesion thickness at the intake pipe pressure of Determined regardless of.

Therefore, in this embodiment, a certain reference intake pipe pressure (for example,
The total adhesion amount of the injection amount to be supplied to the wall when changing the intake pipe pressure from OmmHgabs) to an arbitrary intake pipe pressure is
As shown in the figure, the intake pipe pressure when the intake valve is fully closed is stored in the ROM in advance in the form of a map.

The 23rd area is the predetermined crank angle (360° CA) of this embodiment.
), and in step 230, the basic fuel injection time TP is calculated from the predicted value PMSM2 of the intake pipe pressure calculated in FIG. 19 above and the engine rotational speed NE. Calculate in the same way. In the next step 232, a correction coefficient FK for the fuel injection amount, which is determined by G such as the intake air temperature and the engine cooling water temperature, is calculated. In the next step 234, from the map shown in FIG.
Calculate MWET. Then, in the next step 236, the basic fuel injection time is multiplied by the correction coefficient FK, and the value obtained by subtracting the previous fuel adhesion amount FMWET Ot+ from the currently determined P and fuel adhesion IFMWET is added as a correction addition value. Find the fuel injection time TAU.

This correction addition amount represents the amount of change in fuel adhesion amount caused by a change in intake pipe pressure. and step 238
RAM
to be memorized.

By controlling the fuel injection amount as described above, the second
As shown in Figure 4, the amount of fuel shown in the shaded area is increased, and even if the fuel adheres to the inner wall of the engine by the thickness of the fuel, the amount of fuel supplied to the engine will still reach the required value due to the additional amount of correction. Become. Note that FIG. 27 shows the throttle opening, predicted values of intake pipe pressure, and changes in air-fuel ratio.
In this example, unlike the conventional example shown by the broken line, lean spikes do not occur and the fluctuations in the air-fuel ratio are reduced.

Next, a fourth embodiment of the present invention will be described. In the third embodiment described above, the fuel injection amount was controlled by the amount of fuel adhering to each injection, but in consideration of the fact that the adhesion of fuel to the engine wall is not instantaneously stable, this embodiment By attenuating the correction addition amount for each injection when the amount of air flowing into the combustion chamber is small and reflecting it in subsequent injections, the amount of fuel supplied to the combustion chamber is made equal to the required value. FIG. 28 shows the fuel injection calculation routine of this embodiment, for example, at a predetermined crank angle (3
Executed every 60° CA). In addition, in FIG. 28, the same parts as in FIG. 23 are given the same reference numerals, and the explanation will be omitted. After calculating the fuel adhesion amount FMWET in step 234, the correction addition IFAE is calculated in step 240 according to the following formula.

FAE20, 2・F A Eot++ + F M W
E TF M W E T OLD...(24)
In addition, FAEOLll is the correction addition 3γ amount calculated last time,
FM W ET 0L11 is the previously calculated amount of fuel adhering to the wall surface.

In the above equation (24), the previous correction addition amount F A E o
t.

is multiplied by 0.2, so the previous correction addition amount is 80
% attenuation, and 20% of the previous correction addition amount is reflected in the current correction addition amount. The optimum method for this attenuation is selected depending on the engine, and as mentioned above, it may be attenuated by a predetermined amount at every predetermined crank angle (360° CA in the above example), or it may be attenuated by a predetermined amount at every predetermined time. It may also be attenuated step by step.

In the next step 242, the fuel injection time TAU is calculated using the basic fuel injection time, the correction coefficient FK, and the correction addition amount FAE in the same manner as described above. and step 244
, set the correction addition amount FAE to the previous correction addition amount FAEO.
At the same time, it is stored in RAM as LD, and the fuel adhesion amount FM is
WET to previous fuel adhesion amount F M W E T OLD
It is stored in RAM as .

In addition, in FIG. 25 above, an example was explained in which the amount of fuel deposited is determined according to the intake pipe pressure when the intake valve is fully closed.
The amount of fuel deposited also changes depending on the engine speed, so the second
As shown in FIG. 8, it may be stored as a map that changes with intake pipe pressure and engine speed as variables. In addition, the amount of fuel adhering also changes depending on the engine temperature, and the lower the engine temperature, the more the amount of adhering fuel, so this engine temperature may be further determined as a variable.In addition, in the above embodiment, the weighted average value is Although an example of predicting the intake pipe pressure has been explained, the intake pipe pressure may be predicted according to the above formula 00, or the intake pipe pressure may be predicted by processing the intake pipe pressure in a steady state with a first-order lag element. . Furthermore, although the above example describes an example in which the basic fuel injection time is determined based on the intake pipe pressure and the engine speed when the amount of air flowing into the bypass passage is large, the present invention is not limited to this, and the present invention is not limited to this. The amount of intake air is detected by an air flow meter, Karman vortex flow sensor, hot wire flow sensor, etc. placed in It can also be applied to internal combustion engines that require time. Furthermore, the above-mentioned second to
The intake pipe pressure prediction method and fuel injection amount correction method in the fourth embodiment can also be applied to fuel injection amount control when the amount of air flowing into the bypass passage is small.

Furthermore, in the above example, the control of the fuel injection amount is switched depending on whether or not the opening degree of the ISC valve exceeds a predetermined value. The fuel injection amount control jB may be switched by determining whether or not the air-fuel ratio feedback condition is satisfied, and the opening degree of the ISC pulp may be detected from the number of pulses of the pulse motor. However, the control of the fuel injection amount may be switched by determining whether the opening degree of the ISO valve is less than or equal to a predetermined opening degree. In addition, when driving at high altitudes, the air density decreases and controlling the air-fuel ratio based on the throttle opening may shift to the rich side. It may be determined whether or not the vehicle is running, and the fuel injection amount may be controlled based on the output of the physical quantity detection means while the vehicle is running at a high altitude.

[Brief explanation of drawings]

Fig. 1 is a flow chart showing the main routine of the first embodiment of the present invention, Fig. 2 (1) is a diagram showing the relationship between the throttle opening corresponding to the ISC valve opening and the intake pipe pressure; 2
Figure (2) is a diagram showing changes in the air-fuel ratio feedback correction coefficient FAF during air-fuel ratio feedback control;
) is a line showing the change in air-fuel ratio during air-fuel ratio open-loop control, and Figure 3 is a line showing the difference between the intake pipe pressure determined by the conventional throttle opening and engine speed and the actual intake pipe pressure. Figure 4 is a diagram showing the difference between the conventional fuel injection amount determined by throttle opening and engine rotational speed and the required fuel injection amount, and Figure 5 is a diagram for explaining the principle of the third embodiment. 6 is a diagram showing the change in actual intake pipe pressure in the intake pipe with respect to time in the third embodiment, and FIG.
FIG. 8 is a block diagram for explaining the aspect of the fourth B.
FIG. 9 is a schematic diagram showing an internal combustion engine equipped with a fuel injection amount control device according to an embodiment of the present invention, FIG. 10 is an equivalent circuit diagram of a throttle opening sensor, and FIG. 11 is a block diagram for explaining the present invention. is a block diagram showing details of the control circuit in FIG. 10, FIG. 12 is a diagram showing a map of intake pipe pressure in a steady state, and FIG. 13 is a diagram showing a map of coefficients related to weighting of weighted average values. FIG. 14 is a diagram showing a map of basic fuel injection time, FIG. 15 is a flowchart showing a routine for calculating the air-fuel ratio feedback correction coefficient FAF, and FIG. 16 is a fuel injection amount calculation routine according to the first embodiment of the present invention. FIG. 17 is a flowchart showing the ignition advance calculation routine of the above embodiment, and FIGS. 18 (1) and (2) show changes in air-fuel ratio and intake pipe pressure between the conventional example and the above embodiment. 19 is a flowchart showing a routine for calculating the predicted value of the intake pipe pressure according to the second embodiment of the present invention, FIG. 20 is a flowchart showing the fuel injection time calculation routine of the second embodiment, and FIG. 22 and 22 are diagrams showing changes in the predicted value of intake pipe pressure, etc. in the second embodiment, FIG. 23 is a flowchart showing the fuel injection time calculation routine in the third embodiment of the present invention, and FIG. The figure is a diagram showing the relationship between fuel wall adhesion thickness and intake pipe pressure.
25 and 26 are diagrams showing a map of the corrected injection amount, FIG. 27 is a diagram showing changes in the air-fuel ratio, etc. of the third embodiment in comparison with the conventional example, and FIG. 28 is a diagram showing the present invention. 12 is a flowchart showing a fuel injection amount calculation routine according to a fourth embodiment of the present invention. 8... Throttle valve, 1-0... Throttle opening sensor, 48... Rotation angle sensor.

Claims (1)

[Claims] (1) Controls the fuel injection amount of an internal combustion engine equipped with a sub-control valve that controls the amount of air flowing into the sub-intake passage that communicates the upstream side of the main intake passage where the throttle valve is located and the downstream side of the throttle valve. A fuel injection amount control device for an internal combustion engine includes a throttle opening detection means for detecting the throttle opening, a rotation speed detection means for detecting the engine rotation speed, and a rotation speed detection means for detecting the engine rotation speed, and a throttle opening detection means for detecting the throttle opening, a rotation speed detection means for detecting the engine rotation speed, and a rotation speed detection means for detecting the engine rotation speed. a physical quantity detecting means for detecting a physical quantity; and controlling a fuel injection amount based on a throttle opening detected when the opening of the sub-control valve is equal to or less than a predetermined opening and a detected engine rotational speed; The fuel injection amount control means controls the fuel injection amount based on the physical quantity detected when the opening degree of the control valve exceeds the predetermined opening degree and the detected engine rotation speed. Fuel injection amount control device for internal combustion engines.