JP3337338B2 - Apparatus for estimating intake air amount of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for estimating the amount of air taken into an internal combustion engine.

[0002]

2. Description of the Related Art In recent years, there has been proposed a method of applying a fluid dynamic model to an intake system of an internal combustion engine and estimating a correct cylinder intake air amount by a model formula. The applicant of the present application also disclosed in JP-A-6-74076 that the throttle valve was regarded as an orifice and the amount of air passing through the throttle was determined from the differential pressure before and after the throttle valve using the principle formula of a throttle type flow rate. A method to calculate the cylinder intake air volume based on the above was proposed.

[0003]

However, such a fluid dynamics model is based on an ideal state, and it is difficult to accurately specify various constants (specific heat ratio, etc.) used in modeling. In addition, since the equations of fluid dynamics require calculation of powers, square roots, and the like, approximate values are used in practical use. For these reasons, modeling errors cannot be wiped out.

Therefore, it is extremely important how to reduce the error between the cylinder intake air amount obtained from this model and the actual cylinder intake air amount. In order to improve this point, the present applicant has assumed a fluid dynamics model, but does not require complicated calculations, absorbs the errors of the model formulas, and makes the engine operation transient state, deterioration, variation, aging, etc. And a technique for more accurately estimating the cylinder intake air amount has been proposed (Japanese Patent Application No. 5-208835).

An object of the present invention is to further improve the already proposed method, to further reduce the error between the cylinder intake air amount obtained from the fluid dynamic model and the actual cylinder intake air amount, and to reduce the cylinder intake air amount. Is to provide an intake air amount estimating device for an internal combustion engine, which can more accurately estimate the intake air amount.

[0006]

Therefore, an apparatus for estimating an intake air amount of an internal combustion engine according to the present invention has an engine speed Ne,
First means for detecting the operating state of the internal combustion engine, including the throttle opening θTH and the chamber pressure Pb, and a steady state based on at least the engine speed Ne and the chamber pressure Pb detected by the first means. A second means for obtaining an intake air amount Gc 'into the combustion chamber during an operation state;
Third means for obtaining a first effective opening area A of the throttle based on the throttle opening θTH detected by the means and the chamber pressure Pb, and a first-order lag value of the first effective opening area A of the throttle. Fourth means for obtaining the value as the second effective opening area ADELAY of the throttle, the first effective opening area A obtained by the third means and the second effective opening area ADELAY obtained by the fourth means. By correcting the intake air amount Gc 'based on the following equation, the actual intake air amount Gc is calculated as Gc = Gc' × (A /
ADELAY), the intake system from the throttle to the combustion chamber is modeled and regarded as one chamber, and based on this intake system model, the actual intake air amount taken into the combustion chamber. In the apparatus for estimating the intake air amount of the internal combustion engine for estimating Gc, the fourth means receives a detection result of the detection means for detecting an increase or decrease of the charged air amount Gb filled in the chamber, and receives a detection result of the detection means. Setting means for individually setting the first-order delay correction coefficient B of the throttle opening depending on whether the charged air amount Gb has increased or decreased, and based on the first-order delay correction coefficient B set by the setting means. Computing means for calculating a first-order lag value of the first effective opening area A of the throttle.

Further, in the apparatus for estimating the intake air amount of an internal combustion engine according to claim 2, the above-mentioned detecting means detects the increase or decrease of the charged air amount Gb based on the increase or decrease of the throttle opening θTH. It is constituted as.

Furthermore, in the internal combustion engine intake air amount estimating apparatus according to the third aspect, the detecting means according to the first and second aspects is provided, wherein the detecting means detects the change in the intake manifold volume, the change in the valve timing of the internal combustion engine, the change in the atmospheric pressure and the target. Based on at least one of the changes in the air-fuel ratio,
It is configured as means for detecting an increase or decrease in the charged air amount Gb.

In the present invention, the term "steady operation state" refers to a period in which the charged air amount Gb is substantially constant without any increase or decrease in the charged air amount Gb.
The period during which b fluctuates.

[0010]

In the intake air amount estimating device for an internal combustion engine according to the first aspect, the detecting means detects an increase or a decrease in the charged air amount Gb, and based on the detection result, the setting means detects the charged air amount Gb. The first order delay correction coefficient B of the throttle opening is individually set in accordance with the case where the value increases and the case where the value decreases. By performing such a setting, the behavior of the intake air differs between when the filling air amount Gb increases and when the filling air amount Gb decreases, but it is preferable that the behavior is appropriately followed when the filling air amount Gb increases and decreases. , A first order delay correction coefficient B of the throttle opening is set.

Further, in the intake air amount estimating apparatus for an internal combustion engine according to the second aspect, attention has been paid to the movement of the throttle valve which is a main factor when the charged air amount Gb fluctuates. That is,
When the throttle valve is displaced in the opening direction, the operating state is an acceleration state, and in this case, the charged air amount Gb tends to increase. When the throttle valve shifts in the closing direction, the operation state is a deceleration state, and in this case, the charged air amount Gb tends to decrease. Thus, by detecting the movement of the throttle valve by the detecting means, it is possible to detect an increase or decrease in the charged air amount Gb.

Further, in the intake air amount estimating apparatus for an internal combustion engine according to the third aspect, the charged air amount Gb may be changed not only by the operation of the throttle valve but also by a change in the volume of the intake manifold.
Detected by these detecting means, it is possible to detect an increase or decrease in the charged air amount Gb.

[0013]

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

In FIG. 1, reference numeral 10 denotes a four-cylinder internal combustion engine. The intake air introduced from an air cleaner 14 disposed at the tip of an intake passage 12 is controlled by a throttle valve 16 while its flow rate is adjusted by a surge tank. The fuel flows into the first to fourth cylinders via the intake manifold 20 and the intake manifold 20. An injector 2 is provided near an intake valve (not shown) of each cylinder.
2 is provided, from which fuel is injected. An air-fuel mixture in which the injected fuel and the intake air are integrated is ignited by an ignition plug in each cylinder, burned, and drives a piston of the internal combustion engine. The exhaust gas after the combustion is discharged to an exhaust manifold 24 through an exhaust valve, and the exhaust pipe 26
And is purified by the three-way catalytic converter 28 and discharged out of the engine.

A crank angle sensor 34 for detecting a crank angle position of a piston is provided in a distributor (not shown) of the internal combustion engine. In addition, a throttle for detecting an opening degree θ TH of the throttle valve 16 is provided. An opening degree sensor 36 and an intake pressure sensor 38 for detecting the intake pressure (chamber pressure) Pb downstream of the throttle valve 16 as an absolute pressure are also provided. An atmospheric pressure sensor 40 for detecting the atmospheric pressure Pa, an intake air temperature sensor 42 for detecting the temperature TA of the intake air, and a humidity sensor 44 for detecting the humidity of the intake air are provided upstream of the throttle valve 16. . Further, the intake passage 12 is provided with a bypass passage 32 for adjusting the amount of secondary air, which bypasses an intake passage before and after the throttle valve 16. By driving the solenoid valve 90, the bypass passage 32 is provided. Open and close. In the exhaust system, a wide-range air-fuel ratio 46 including an oxygen concentration detecting element is provided downstream of the exhaust manifold 24 and upstream of the three-way catalytic converter 28, and detects the air-fuel ratio of the exhaust gas. Outputs of these sensors 34 and the like are output from the control unit 5.
Sent to 0.

FIG. 2 shows the details of the control unit. The output of the wide-range air-fuel ratio sensor 46 is input to the detection circuit 52, and the air-fuel ratio A / F is detected. The output of the detection circuit 52 is A /
The CPU 56, the ROM 58, and the R
The data is taken into the microcomputer constituted by the AM 60 and stored in the RAM 60. Similarly, the analog output of the throttle opening sensor 36 and the like is
2, multiplexer 64 and second A / D conversion circuit 66
Through the microcomputer. The output of the crank angle sensor 34 is supplied to a waveform shaping circuit 68.
After the waveform is shaped, the output value is counted by the counter 70, and the count value is input into the microcomputer. In the microcomputer, the CPU 56 calculates a control value, which will be described later, according to a command stored in the ROM 58, and drives the injector 22 of each cylinder via the drive circuit 72.

Here, the basic principle of a method of estimating the cylinder intake air amount using a fluid dynamic model employed in the present embodiment will be schematically described (see Japanese Patent Application Nos. Hei 6-19723).
No. 8).

According to this method, the behavior of air in an intake system of an internal combustion engine is modeled by a physical equation (FIG. 3), and based on an air amount Gth passing through a throttle and an air amount Gb charged into a chamber, an in-cylinder air amount is calculated. This is a method for estimating the amount of intake air (actual intake air amount) Gc to be taken into the engine. Here, the “chamber” means not only a part corresponding to a so-called surge tank but also all parts through which air flows from the throttle to the intake port, and means an effective volume actually acting as a chamber. .

First, as shown in FIG. 4, a throttle projection area (projection area of the throttle in the longitudinal direction of the intake pipe) S is obtained from the throttle opening θTH in accordance with preset characteristics. On the other hand, as shown in FIG.
The coefficient C (the product of the flow rate coefficient α and the gas expansion correction coefficient ε) is obtained according to another characteristic set for the pressure and the intake pressure (in-chamber pressure) Pb. In the so-called throttle full-open range, the throttle does not function as a throttle, so the throttle full-open range is obtained as a critical value for each engine speed, and when the detected throttle opening exceeds this critical value, This critical value is defined as the throttle opening.

Next, the amount of air Gb in the chamber is obtained from the equation (1) based on the equation of state of gas, and the amount of air ΔGb filled in the chamber this time is obtained from the pressure change ΔP in the chamber according to the equation (2). Assuming that the amount of air filled in the chamber this time is not naturally taken into the cylinder combustion chamber, the amount of intake air Gc per unit time ΔT is
It can be expressed as in Equation 3.

[0021]

(Equation 1)

[0022]

(Equation 2)

[0023]

(Equation 3)

On the other hand, as shown in FIG. 6, the above-mentioned ROM 58 stores the fuel injection amount Timap in the steady operation state in accordance with the so-called speed density method.
Is set in advance so as to be searchable from the data and the intake pressure Pb. Further, since the fuel injection amount Timap retrieved here is set according to the target air-fuel ratio A / F determined according to the engine speed Ne and the intake pressure Pb, as shown in FIG. Basic value of fuel ratio A / F KBS
Is also mapped and stored in advance so that the engine speed Ne and the intake pressure Pb can be freely searched. The fuel injection amount Timap is set so as to satisfy the steady-state operation state in the aforementioned fluid dynamics model. The valve opening time of the injector 22 is set directly as a unit.

Here, under a certain condition in a steady operation state (a condition defined by the engine speed Ne1 and the intake pressure Pb1), the fuel injection amount Timap1 determined by the map search is as shown in Expression 4. .

[0026]

(Equation 4)

By preparing this map value so as to satisfy the above-described model formula, the fuel injection amount Timap1 'in the steady operation state, which is determined based on the fluid dynamic model.
Naturally coincides with the fuel injection amount Timap1 determined by the map search.

On the other hand, the fuel injection amount Timap1 'in the steady operation state and the fuel injection amount Timap2' in the transient operation state, which are determined based on the fluid dynamics model, are obtained by setting the target air-fuel ratio to the stoichiometric air-fuel ratio (14.7: Assuming 1), it is expressed by Expression 5 and Expression 6.

[0029]

(Equation 5)

[0030]

(Equation 6)

In both equations, comparing the throttle passing air amount Gth1 in the steady operation state and the throttle passing air amount Gth2 in the transient operation state, only the effective opening areas A1 and A of the throttle are different. Therefore, the throttle-passing air amount Gth2 in the transient operation state can be expressed by Expression 7.

[0032]

(Equation 7)

By using the ratio between the effective opening area of the throttle valve in the steady state and the effective opening area of the throttle valve in the transient state based on the equations (3) and (7), the throttle-passing air amount Gth1 in the steady state is calculated. In addition, the throttle passing air amount Gth2 in the transient operation state can be expressed.

Further, assuming that the current effective opening area of the throttle valve is A and the effective opening area of the throttle valve in the steady operation state is A1, the effective opening area A1 of the throttle valve in the steady operation state is It can be grasped as a first-order delay of the effective opening area A of the valve (FIG. 8). That is, if the first-order lag of A is called "ADELAY", it is understood that A1 and ADELAY have substantially the same value. Therefore, when approximating a model using the concept of a fluid dynamic model, A / (first order delay of A) may be used.

As shown in FIG. 9, in the transient operation state, at the moment when the throttle is opened, the pressure difference before and after the throttle is large, so that the amount of air passing through the throttle flows at a stretch and gradually falls to a steady state. The throttle passing air amount Gth in the state can be expressed by the ratio A / ADELAY. In the steady operation state, this value is "1" as shown in the lower graph of FIG. Hereinafter, this ratio is referred to as "RATI
OA ".

The effective opening area of the throttle greatly depends on the throttle opening, and changes substantially following the change in the throttle opening (FIG. 10). Therefore, the above-described first-order lag value of the effective opening area is treated equivalently to the first-order lag value of the throttle opening. Further, in order to eliminate the delay in which the chamber filling air amount ΔGb is reflected on the intake air amount Gc, the first order delay of the value ΔGb is considered in addition to the first order delay of the throttle opening.

Thus, by calculating the chamber filling air amount Gb from the throttle passing air amount Gth, the intake air amount Gc can be obtained based on the throttle passing air amount Gth. This simplifies the configuration and reduces the amount of calculation. Specifically, the intake air amount Gc per unit time ΔT can be expressed as in Expression 8.
Also, when Expressions 9 and 10 are expressed in the form of a transfer function,
Equation 11 is derived. As shown in equation (11), the intake air amount Gc can be obtained from the primary delay value of the throttle passing air amount Gth.

[0038]

(Equation 8)

[0039]

(Equation 9)

[0040]

(Equation 10)

[0041]

[Equation 11]

FIG. 11 is a block diagram showing such a series of arithmetic processing. Since the intake air amount Gc can be handled in the same manner as the fuel injection amount, in the following block diagrams and the like, the intake air amount is handled as the fuel injection amount for convenience. In the figure, "(1-
B) / (z−B) ”means a first-order lag in a discrete transfer function.

Therefore, under certain conditions in the steady operation state (conditions defined by the engine speed Ne and the intake pressure Pb)
When the fuel injection amount determined by the map search is described as Timap, the fuel injection amount Tout to be actually output is determined by the following equation. Tout = Timap × RATIO-A Further, when the behavior of the intake air was verified through simulation, the behavior was different when the chamber filling air amount Gb increased and decreased. This is shown in FIG. In FIG. 12, attention is paid to the movement of the throttle valve, which is a main factor when the chamber filling air amount Gb fluctuates, and the intake air amount (throttle amount) when the throttle valve moves in the opening direction and in the closing direction. Air flow, cylinder intake air, chamber filling air)
Shows the change behavior. FIG. 13 shows the pressure fluctuation in the chamber with respect to the fluctuation of the throttle valve. Also in this case, the behavior of the pressure change in the chamber is different between the case where the throttle valve shifts in the opening direction and the case where the throttle valve shifts in the closing direction. The reason why the behavior of the intake air changes in the opening direction and the closing direction of the throttle valve in this way seems to be one of the factors that the intake air is a compressible fluid.

Therefore, the apparatus for estimating the intake air amount of the internal combustion engine according to the present embodiment, in order to more accurately estimate the cylinder intake air amount, determines whether the throttle valve of the throttle increases or decreases when the chamber filling air amount Gb decreases. The first-order lag correction coefficient B is set individually.

The operation of the intake air amount estimating apparatus will be described below with reference to the block diagram of FIG. 14 and the main flowchart of FIG. This flowchart is started at each TDC position.

First, the engine speed N detected by each sensor
e, intake pressure Pb, throttle opening θTH, pressure Pa, engine cooling water temperature Tw, etc. are read (S10). The throttle opening θTH learns the fully closed throttle opening in the idling operation state and uses the learned value.

Next, it is determined whether or not the engine is being cranked (started) (S20). If it is determined that the engine is not being cranked ("NO" in S20), subsequently, it is determined whether or not fuel cut is being performed. Is determined (S30). If "NO" is determined in S30, a map (FIG. 6) stored in the ROM 58 is searched based on the engine speed Ne and the intake pressure Pb, and the fuel injection amount Timap (steady operation) in the steady operation state is searched. The intake air amount Gc 'in the state is obtained (S4).
0). Thereafter, the retrieved fuel injection amount Timap is subjected to pressure correction or the like as needed (not shown).

Next, a primary delay value θTH-D of the throttle opening θTH read in S10 is calculated (S50). FIG. 16 shows a flowchart of the arithmetic processing performed here. This flowchart is also started at each TDC position.

First, it is determined whether the operating state is an acceleration state or a deceleration state based on the throttle opening θTH obtained from the throttle opening sensor 36 (S51). This acceleration / deceleration determination is based on the throttle opening obtained at the current timing
(K), and assuming that the throttle opening obtained at the previous timing is θTH (k−1), θTH (k) and θTH (k−
This is done by comparing 1). That is, θ
If TH (k) ≧ θTH (k−1), it is determined that the vehicle is accelerating,
If θTH (k) <θTH (k−1), it is determined that the vehicle is in a deceleration state.

At this time, if it is determined that the vehicle is in the acceleration state ("YES" in S51), the acceleration correction coefficient B ₁ (for example, B ₁ = 0.4) is replaced with the throttle first delay correction coefficient B 1
(S52). On the other hand, if it is determined that the vehicle is in the deceleration state ("NO" in S51), the correction coefficient B for deceleration is used.
₂ (for example, B ₂ = 0.8) is set as the throttle primary delay correction coefficient B (S53).

Next, using the throttle primary delay correction coefficient B thus set, a primary delay transfer function "(1-B) / (z-B)" of the throttle opening .theta.TH is set (FIG. 2B). S54). Then, a primary delay value θTH-D of the throttle opening is calculated based on the set primary delay transfer function “(1-B) / (z−B)” and the throttle opening θTH (S55).

Subsequently, returning to the main flowchart of FIG. 15, based on the throttle opening θTH and the intake pressure Pb,
The current effective opening area A of the throttle is calculated by the method described above (S60). Next, the throttle opening 1
A first order delay value ADELAY of the effective opening area of the throttle is calculated from the next delay value θTH-D and the intake pressure Pb (S70).

Next, "RATIO-A" is calculated from the equation: RATIO-A = (A + ABYPASS) / (A + ABYPASS) DELAY (S80). ABYPASS means the amount of air (shown as “lift amount” in FIG. 14) that is drawn into each cylinder combustion chamber via the bypass passage 32 or the like without passing through the throttle valve. In order to determine the amount, it is necessary to consider this amount of air, and therefore, the calculation is performed in consideration of this amount of air. Specifically, a value corresponding to the air amount is converted into a throttle opening ABYPASS in accordance with a predetermined characteristic, obtained and added to the effective opening area A, and the sum (A + ABYPASS) and an approximation of the first order delay are obtained. The ratio of the value “(A + ABYPASS) DELAY” is obtained, and is set as RATIO-A.

As described above, as a result of addition to both the numerator and the denominator, even if there is an error in the measurement of the amount of air taken into each cylinder combustion chamber without passing through the throttle valve, the measured fuel injection amount is not increased. Impact is reduced. Subsequently, the fuel injection amount Tout (Gc) corresponding to the throttle passing air amount is calculated by multiplying Timap (Gc ') obtained by searching in S40 by RATIO-A (S90).

If it is determined in step S20 that cranking is being performed ("YES" in step S20), a predetermined table (not shown) is searched from the water temperature Tw to calculate the fuel injection amount Ticr during cranking. (S21) Then, the fuel injection amount Tout is determined based on the equation (not described) of the start mode (S22).

On the other hand, if it is determined in S30 that the fuel is cut ("YES" in S30), the fuel injection amount Tout is set to zero (S31).

As described above, when the first-order throttle delay correction coefficient B is separately held for acceleration and deceleration, the intake air is more accurately compared to the case where the first-order throttle delay correction coefficient B is fixed. It was evaluated whether the amount could be estimated. This evaluation was performed with the engine speed, intake pressure, and the like kept constant.

FIGS. 17A to 17C show the evaluation results. FIG. 17A shows a transition state of the throttle opening θTH, in which the throttle is rapidly opened to a predetermined opening (acceleration state), and thereafter, the throttle is rapidly closed to a predetermined opening (deceleration state). ing. In this state where the throttle is shifted, when the first-order throttle delay correction coefficient B is fixed (FIG. 17B), a large variation occurs in the behavior of the air-fuel ratio on the closed side compared to the open side of the throttle. You can see that. On the other hand, when the throttle first-order lag correction coefficient B is set to an appropriate value on the opening side and the closing side of the throttle (FIG. 17C), the variation in the air-fuel ratio is smaller than that in FIG. 17B. It can be seen that the air-fuel ratio has been substantially flat over the entire period. Therefore, it has been confirmed that the intake air amount Gc (fuel injection amount Tout) can be more accurately estimated by setting the correction coefficient B to an appropriate value individually on the opening side and the closing side of the throttle. The vertical axis in FIGS. 17B and 17C indicates the equivalent ratio, that is, Mst / M (Mst: stoichiometric air-fuel ratio, M: air consumption / fuel consumption).

Here, another embodiment will be described with reference to FIG. In the above-described embodiment, the chamber filling air amount Gb
Is detected by focusing only on the throttle opening, which is the main factor, but the chamber filling air amount Gb also increases and decreases due to the following factors. An increase or decrease in the charged air amount Gb is detected. That is, when the engine speed changes,
When the shape of the intake manifold is mechanically changed to increase or decrease its volume, when the atmospheric pressure changes, when the opening / closing timing of the intake and exhaust valves (valve timing) changes, the target air-fuel ratio changes. If you do,
The chamber filling air amount Gb changes substantially.

Therefore, in this embodiment, an increase or decrease in the chamber filling air amount Gb is detected in consideration of these factors comprehensively, and based on the result, a first order delay value θTH of the throttle opening is set.
An example of calculating -D will be described.

FIG. 18 shows the primary delay value θ of the throttle opening.
4 shows a flowchart for executing a TH-D calculation process. This flowchart shows the arithmetic processing performed in S50 in the main flowchart shown in FIG. 15, and is started at each TDC position.

First, the valve timing V / T is set to “Hig
h "or" Low "(S100), and in any case, the throttle opening .theta.
It is determined whether the operation state is the acceleration state or the deceleration state from the change state of TH (S101, S102).

If it is determined in S101 that the vehicle is in the acceleration state ("YES" in S101), the correction coefficient B during acceleration is used.
₃ (for example, B ₃ = 0.4) is set as the throttle first-order delay correction coefficient B (S103). If it is determined that the vehicle is in the deceleration state (“NO” in S101), the correction coefficient B _{4 for} deceleration is set. (For example, B ₄ = 0.8) is set as the throttle primary delay correction coefficient B (S104).

Similarly, if it is determined in S102 that the vehicle is accelerating ("YES" in S102), the acceleration coefficient B ₅ (for example, B ₅ = 0.3) is set to the throttle 1 speed.
Set the next delay correction coefficient B (S105), when it is determined that the deceleration state ( "NO" in S102), the correction coefficient of deceleration B ₆ (e.g., B ₆ = 0.6), throttle 1 It is set as the next delay correction coefficient B (S106). As described above, when the valve timing V / T is “High”, the primary throttle delay correction coefficient B tends to be smaller than when the valve timing is “Low”. In any case, the value during acceleration tends to be smaller than the value during deceleration.

Subsequently, the throttle primary delay correction coefficient B set in S103 to S106 is further corrected according to the engine speed, the atmospheric pressure, and the like. In this case, first, as shown in FIGS. 19A to 19D, the correction coefficients KADNe, KADPA, KADTA, and KADAF according to the engine speed Ne, the atmospheric pressure PA, the intake air temperature TA, and the target air-fuel ratio AF. Are determined in advance, and corresponding various correction coefficients KADNe, KADPA,
Search for and obtain KADTA and KADAF (S10
7). Next, with respect to the throttle primary delay correction coefficient B set in any of S103 to S106, the obtained various correction coefficients KADNe, KADPA, KADTA, and KA are obtained.
DAF is multiplied by each, and this value is set as a final throttle primary delay correction coefficient B (S108).

Next, using the throttle primary delay correction coefficient B thus set, a primary delay transfer function "(1-B) / (z-B)" of the throttle opening θTH is set (S109). ), The set first-order lag transfer function “(1-
B) / (z−B) ”and the throttle opening θTH to calculate a first order delay value θTH-D of the throttle opening (S11).
0).

The throttle opening 1 thus determined
Using the next delay value θTH-D, the fuel injection amount Tout is calculated according to the main flowchart of FIG.

In the embodiment shown in FIG. 18, it is exemplified that the valve timing V / T is determined to be "High" or "Low" in S100 of the flowchart. However, in this S100, the change in the volume of the intake manifold is determined. It may be detected. In this case, there is control to mechanically change the form of the intake manifold,
What is necessary is just to detect this control signal. As a result, when the volume of the intake manifold increases, the response delay increases, so the process proceeds to S101 in the flowchart of FIG. 18, and the throttle primary delay correction coefficient B is set to a large value. On the other hand, if it decreases, the response delay becomes smaller, and the process proceeds to S102 in the flowchart, where the throttle first-order delay correction coefficient B is set to a small value.

Each of the above-described methods of calculating the fuel injection amount Tout can express from a steady operation state to a transient operation state by a simple algorithm, and the fuel injection amount in the steady operation state is guaranteed to some extent by a map search. At the same time, the fuel injection amount can be optimally determined without requiring complicated calculations. In addition, since the primary delay correction coefficient of the throttle opening is set according to the behavior of the intake air which is different between the time of increase and the time of decrease, the intake air amount can be more accurately estimated, and the controllability and control can be improved. The system can be further improved.

In the above-described embodiment, an example is shown in which the fuel injection amount Timap is mapped in advance. Instead, the intake air amount Gc 'in the steady operation state is mapped and stored in the ROM 58. You may keep it.

Further, in the illustrated embodiment, the fuel injection amount is determined according to the estimated intake air amount. However, the present invention is not limited to this example. Other engine control parameters such as an ignition timing and an exhaust gas recirculation amount (EGR amount) can be calculated according to the intake air amount.

[0072]

As described above, the intake air amount estimating device for an internal combustion engine according to the first aspect of the present invention includes the detecting means, so that the increase or decrease of the charged air amount Gb can be detected. The primary delay correction coefficient of the throttle opening can be individually set based on the detection result. Therefore,
The process of estimating the intake air amount corresponding to the behavior of the intake air that is different when the charged air amount Gb increases and decreases can be performed. Therefore, it is possible to more accurately estimate the amount of air flowing into the cylinder based on the amount of air passing through the throttle than before, and it is possible to further improve the controllability of the internal combustion engine.

Further, in the device for estimating the intake air amount of an internal combustion engine according to the second aspect, the detecting means is provided with a throttle opening θ.
As a means for detecting an increase or decrease in the charged air amount Gb based on an increase or decrease in TH, the charged air amount Gb
Can be estimated based on the movement of the throttle valve, which is the main factor when the pressure fluctuates.

Further, in the intake air amount estimating device for an internal combustion engine according to the third aspect, the detecting means also detects other factors contributing to the increase or decrease of the charged air amount Gb, such as a change in the atmospheric pressure. It is possible to more accurately estimate the intake air amount.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an arrangement position of an internal combustion engine and various sensors according to an embodiment;

FIG. 2 is a block diagram showing a configuration of a control device in the intake air amount estimating device for the internal combustion engine.

FIG. 3 is an explanatory diagram showing a fluid dynamic model adopted in the present embodiment.

4 is a block diagram showing a method of calculating an effective opening area of a throttle valve using a flow coefficient or the like using the fluid dynamic model of FIG. 3;

FIG. 5 is an explanatory diagram showing map characteristics of coefficients used in the calculation of FIG. 4;

FIG. 6 is an explanatory diagram showing a map characteristic of a fuel injection amount in a steady operation state.

FIG. 7 is an explanatory diagram showing a map of a target air-fuel ratio.

FIG. 8 is a data diagram showing a simulation result of an effective opening area of a throttle.

FIG. 9 is an explanatory diagram showing a steady operation state and a transient operation state in this embodiment.

FIG. 10 is an explanatory diagram showing a relationship between a throttle opening and an effective opening area of a throttle.

FIG. 11 is a block diagram illustrating a calculation process of a fuel injection amount (intake air amount).

FIG. 12 is a data diagram showing behavior of intake air during acceleration / deceleration.

FIG. 13 is a data diagram showing that the behavior of the pressure in the chamber is different between the opening side and the closing side of the throttle valve.

FIG. 14 is a block diagram illustrating a calculation process of a fuel injection amount (amount of intake air) in a case where a correction coefficient for a first-order delay of a throttle is individually set according to an operation state.

FIG. 15 is a main flowchart showing a calculation process of a fuel injection amount (intake air amount).

FIG. 16 is a flowchart showing θ in the main flowchart of FIG.
It is a flowchart which shows only the calculation process of the primary delay value (theta) TH-D of TH.

FIG. 17A is a data diagram showing a transition state of a throttle opening. (B) is a throttle primary delay correction coefficient B
FIG. 9 is a data diagram showing a change in the air-fuel ratio corresponding to a state in which the throttle shifts as shown in FIG. (C) is a data diagram showing a change in the air-fuel ratio corresponding to a state in which the throttle is shifted as shown in (a) when the throttle first-order delay correction coefficient B is separately held on the opening side and the closing side of the throttle. It is.

FIG. 18 is a flowchart showing another embodiment relating to the calculation processing of the primary delay value of the throttle opening.

19A is a graph showing the relationship between the engine speed and the correction coefficient KADNe, and FIG. 19B is a graph showing the relationship between the atmospheric pressure and the correction coefficient KAD.
FIG. 4C is a graph showing a relationship between PA and PA, FIG. 4C is a graph showing a relationship between intake air temperature and a correction coefficient KADTA, and FIG. 4D is a graph showing a relationship between a target air-fuel ratio and a correction coefficient KADFA.

[Explanation of symbols]

10 internal combustion engine, 12 intake path, 16 throttle valve,
20: intake manifold, 36: throttle opening sensor.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-42600 (JP, A) JP-A-6-74076 (JP, A) JP-A-3-260357 (JP, A) JP-A-62-1987 265449 (JP, A) JP-A-8-42380 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/00-45/00 F02D 13/00-28/00

Claims (3)

(57) [Claims] 1. A first means for detecting an operating state of an internal combustion engine including an engine speed Ne, a throttle opening .theta.TH, and a chamber pressure Pb, and at least the engine speed detected by the first means. A second calculation of the intake air amount Gc 'into the combustion chamber in the steady operation state based on the number Ne and the chamber pressure Pb.
Means for determining a first effective opening area A of the throttle based on at least the throttle opening θTH detected by the first means and the pressure Pb in the chamber; Fourth means for obtaining a first-order lag value of the first effective opening area A and using the value as a second effective opening area ADELAY of the throttle; and the first effective opening area A obtained by the third means and the 4
The actual intake air amount Gc 'is corrected by correcting the intake air amount Gc' based on the second effective opening area
and a fifth means for determining c as Gc = Gc '× (A / ADELAY). The intake system from the throttle to the combustion chamber is modeled as one chamber, and based on this intake system model, In the intake air amount estimating device for an internal combustion engine for estimating an actual intake air amount Gc drawn into a chamber, the fourth means includes a detecting means for detecting an increase or a decrease in the charged air amount Gb filled in the chamber. Receiving the detection result of the detection means, and
Setting means for individually setting the first order delay correction coefficient B of the throttle opening depending on whether the value has increased or decreased; based on the first order delay correction coefficient B set by the setting means,
Calculating means for calculating a first-order lag value of the first effective opening area A of the throttle. 2. The intake air for an internal combustion engine according to claim 1, wherein said detecting means detects an increase or a decrease in said charged air amount Gb based on an increase or a decrease in said throttle opening θTH. Quantity estimation device. 3. The method according to claim 1, wherein the detecting means detects a change in the volume of the intake manifold, a change in a valve timing of the internal combustion engine, a change in the atmospheric pressure, and a change in the target air-fuel ratio. Increase in the amount Gb,
3. The intake air amount estimating device for an internal combustion engine according to claim 1, wherein a decrease is detected.