JPH08232748A - Intake air amount estimating device for internal combustion engine - Google Patents

Abstract

PURPOSE: To stabilize estimation processing of an intake air amount by a method wherein during a period wherein the operation state of an engine is considered to be steady, an effective opening area ratio is maintained at a constant value. CONSTITUTION: It is decided by a steady state deciding part 100 that the operation state of an engine is a steady state when a value of an effective opening area ratio RATIO-A is within a range of 0.95-1.05. When it is decided by the steady state deciding part 100 that the operation state of the engine is a steady state, a value of the effective opening area ratio RATIO-A obtained at a current time by a conversion part 101 is replaced with a predetermined value '1.00' and following estimation processing is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake air amount estimating apparatus for an internal combustion engine, which estimates the amount of air taken into the internal combustion engine.

[0002]

2. Description of the Related Art In recent years, a method has been proposed in which a fluid dynamics model is applied to the intake system of an internal combustion engine, and a correct cylinder intake air amount is estimated by a model formula. The applicant of the present invention also previously found that the throttle valve is regarded as an orifice in JP-A-6-74076, and the throttle passing air amount is obtained from the differential pressure before and after the throttle valve by using a throttle type flow rate principle formula. We proposed a method to calculate the cylinder intake air amount based on.

Further, 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 absorbs the error of the model formula without requiring complicated calculation while assuming the fluid dynamics model, and transient state and deterioration of engine operation, variation, secular change, etc. To eliminate
A method for estimating the cylinder intake air amount more accurately has been proposed (Japanese Patent Application No. 5-208835).

[0004]

All of the cylinder intake air amount estimating methods already proposed are methods in which the opening degree of the throttle valve is used as a reference. On the other hand, due to factors such as engine vibration being applied to the throttle body, the opening of the throttle valve may change slightly even in the steady operation state. In this case, if the opening of the throttle valve is given as such a change, the cylinder intake air amount estimation process corresponding to this change is executed, and despite the steady operation state, The actual driving condition was not stable, and it was one of the factors that reduce the driver's rally. Moreover, the relationship between the opening θTH of the throttle valve (butterfly valve) and the intake air amount Gc is as shown in FIG. 17, especially when the opening of the throttle valve slightly changes on the low opening side. Therefore, the estimation process is performed assuming that the intake air amount Gc has largely changed. Therefore, particularly when the throttle valve is on the low opening side, it is necessary to carry out the estimation procedure more stably.

Therefore, an object of the present invention is to provide an intake air amount estimating apparatus for an internal combustion engine, which can stabilize a running state in a steady operation state without lowering the accuracy of the intake air amount estimating process. Especially.

[0006]

Therefore, the intake air amount estimating apparatus for an internal combustion engine according to the first aspect of the present invention is configured so that the engine speed Ne,
Based on the first means for detecting the operating state of the internal combustion engine, which includes the throttle opening θTH and the chamber pressure Pb, and at least the engine speed Ne and the chamber pressure Pb detected by the first means, The second means for obtaining the intake air amount Gc 'into the combustion chamber in the steady operation state, and at least the first throttle opening based on the throttle opening θTH and the chamber pressure Pb detected by the first means. A third means for obtaining the effective opening area A and a first-order lag value of the first effective opening area A of the throttle are obtained, and the obtained value is used as the second value of the throttle.
A fourth means for determining the effective opening area ADELAY, and a fifth means for determining the ratio of the first effective opening area A to the second effective opening area ADELAY and setting this value as the effective opening area ratio RATIO-A of the throttle, By correcting the intake air amount Gc 'on the basis of the effective opening area ratio RATIO-A obtained by the fifth means, the actual intake air amount Gc can be calculated as Gc = Gc' × RATIO
In the intake air amount estimating apparatus for an internal combustion engine, including the sixth means for obtaining -A, when the operating state of the internal combustion engine is within a predetermined range, the operating state of the internal combustion engine is in a steady state. If the operating condition of this internal combustion engine is determined to be a steady state by the steady state determining means to be considered and the steady state determining means, the effective opening area ratio RATIO
And a converting means for converting the value of -A into a predetermined value and giving this value to the sixth means.

Further, in the intake air amount estimating apparatus for an internal combustion engine according to claim 2, the steady state judging means according to claim 1 is used, in which the amount of change in the throttle opening within a predetermined time is
This is configured as means for determining that the operating state of the internal combustion engine is a steady state when it is within a predetermined range.

Further, in the intake air amount estimating apparatus for an internal combustion engine according to claim 3, the steady state judging means according to claim 1 is used, and the effective opening area ratio of the throttle obtained by the fifth means.
When the value of RATIO-A is within a predetermined range near 1, it is configured as means for determining that the operating state of this internal combustion engine is a steady state.

Further, in the intake air amount estimating apparatus for an internal combustion engine according to a fourth aspect, the steady state judging means according to the first aspect is arranged such that the variation amount of the chamber internal pressure Pb within a predetermined time is within a predetermined range. When the internal combustion engine is in the state described above, the operating state of the internal combustion engine is determined to be a steady state.

[0010]

In the intake air amount estimating apparatus for the internal combustion engine according to the first aspect, the steady state determination means determines that the internal combustion engine is in the steady state when the operating state is within a predetermined range. When it is determined to be in the steady state, the conversion means converts the value of the effective opening area ratio RATIO-A into a predetermined value. As a result, even if the value of the effective aperture area ratio RATIO-A fluctuates slightly due to the influence of noise, etc., the effective aperture area ratio RATIO-A is maintained at a constant value during the period considered to be the steady state. It

If the amount of change in the throttle opening is substantially constant, the operating state of the internal combustion engine can be regarded as a steady state. Therefore, the steady state determination means according to claim 2 determines that the operating state of the internal combustion engine is the steady state when the amount of change in the throttle opening within the predetermined time is within a predetermined range. .

Further, the value of the first effective opening area A of the throttle becomes the first-order lag value, and the second effective opening area ADELAY
If it substantially agrees with, it can be considered that the operating state of the internal combustion engine is in a steady state with little change during this period. Therefore, the steady state determination means according to claim 3 determines that the operating state of the internal combustion engine is the steady state when the value of the effective opening area ratio RATIO-A is within a predetermined range near 1. did.

Further, when the amount of change in the chamber internal pressure Pb within a predetermined time is within a predetermined range,
The actual intake air amount Gc is almost constant, and it can be considered that the operating state of the internal combustion engine is a steady state. Therefore, the steady state determining means according to claim 4 determines that the operating state of the internal combustion engine is the steady state when the amount of change in the chamber internal pressure Pb within a predetermined time is within a predetermined range. And

[0014]

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, and the intake air introduced from an air cleaner 14 arranged at the tip of an intake passage 12 has its flow rate adjusted by a throttle valve 16 and a surge tank. It is introduced into the first to fourth cylinders via the intake manifold 18 and the intake manifold 20. An injector 2 is provided near the intake valve (not shown) of each cylinder.
2 is provided and fuel is injected from here. The air-fuel mixture in which the injected fuel and the intake air are integrated is ignited by a spark plug in each cylinder and burned to drive a piston of the internal combustion engine. The exhaust gas after combustion is discharged to the exhaust manifold 24 through the exhaust valve, and the exhaust pipe 2
After passing through 6, it is purified by the three-way catalytic converter 28 and exhausted to the outside of the engine.

A crank angle sensor 34 for detecting the crank angle position of the piston is provided in the distributor (not shown) of the internal combustion engine. In addition to this, a throttle for detecting the opening degree θTH of the throttle valve 16 is provided. An opening 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 that detects the atmospheric pressure Pa, an intake air temperature sensor 42 that detects the temperature TA of the intake air, and a humidity sensor 44 that detects 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 bypassing the intake passages before and after the throttle valve 16 for adjusting the secondary air amount. 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 to detect the air-fuel ratio of the exhaust gas. The outputs of these sensors 34 and the like are output to 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 /
CPU 56, ROM 58 and R via D conversion circuit 54
It is taken into the microcomputer composed of AM60 and stored in RAM60. Similarly, the analog output of the throttle opening sensor 36 and the like is supplied to the level conversion circuit 6
2, multiplexer 64 and second A / D conversion circuit 66
Is input to the microcomputer via the. In addition, the output of the crank angle sensor 34 is the waveform shaping circuit 68.
After the waveform is shaped by, 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 the instruction stored in the ROM 58, and drives the injector 22 of each cylinder via the drive circuit 72.

Here, the basic principle of the method of estimating the intake air amount using the fluid dynamics model adopted in this embodiment will be schematically described (see Japanese Patent Application No. 6-197,238).
issue).

In this method, the behavior of air in the intake system of an internal combustion engine is modeled by a physical formula (FIG. 3), and the amount of air passing through the throttle Gth and the amount of air filled in the chamber Gb are used to calculate the internal cylinder. This is a method of estimating the intake air amount (actual intake air amount) Gc that is taken into the air. The "chamber" includes not only the so-called surge tank equivalent part but also all parts through which air flows between the throttle and the intake port that is the inlet of the cylinder, and the effective volume that actually acts as a chamber is defined. Shall mean.

First, as shown in FIG. 4, the throttle projected area (throttle projected area in the longitudinal direction of the intake pipe) S is obtained from the throttle opening θTH according to a preset characteristic. On the other hand, as shown in FIG. 5, the throttle opening θTH
And a coefficient C (product of flow coefficient α and expansion correction coefficient ε of gas) according to another characteristic set for the intake pressure (chamber pressure) Pb, and multiplied by both to obtain the effective opening area A of the throttle. Since the throttle does not function as a throttle in the so-called throttle fully open region, the throttle fully open region is obtained as a critical value for each engine speed, and when the detected throttle opening exceeds this critical value, This critical value is the throttle opening.

Then, the air amount Gb in the chamber is obtained from the equation 1 based on the gas state equation, and the air amount ΔGb filled in the chamber this time is obtained from the pressure change ΔP in the chamber according to the equation 2. If the amount of air filled in the chamber this time is naturally not 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.

[0022]

[Equation 1]

[0023]

[Equation 2]

[0024]

(Equation 3)

On the other hand, in the above-mentioned ROM 58, as shown in FIG. 6, the fuel injection amount Timap in the steady operation state is calculated based on the so-called speed density system to the engine speed Ne.
It is set in advance so that it can be retrieved from the intake pressure Pb and the intake pressure Pb, and is stored as a map. Further, since the fuel injection amount Timap retrieved here is set according to the target air-fuel ratio A / F which is determined according to the engine speed Ne and the intake pressure Pb, as shown in FIG. Basic value of air-fuel ratio A / F KB
S is also stored in advance as a map so that it can be searched freely from the engine speed Ne and the intake pressure Pb. The fuel injection amount Timap is set so as to satisfy the steady operation state in the fluid dynamics model described above. The valve opening time of the injector 22 is directly set as a unit.

Here, under a certain condition in a steady operation state (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 the equation (4). .

[0027]

[Equation 4]

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

On the other hand, for 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, the target air-fuel ratio is changed to the theoretical air-fuel ratio (14.7: 1), it can be expressed by Equation 5 and Equation 6.

[0030]

(Equation 5)

[0031]

(Equation 6)

In both of these 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 differ. Therefore, the throttle passing air amount Gth2 in the transient operation state can be expressed by the equation (7).

[0033]

(Equation 7)

Based on the equations (3) and (7), by using the ratio of the effective opening area of the throttle valve in the steady state to the effective opening area of the throttle valve in the transient state, 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 the current throttle area. It can be grasped as the primary delay of the effective opening area A of the valve (Fig. 8). That is, when the first-order lag of A is called "ADELAY", it can be seen that A1 and ADELAY have almost the same value. Therefore, when approximating the model using the concept of the fluid dynamics model, A / (first-order lag of A) may be used.

As shown in FIG. 9, in the transient operation state, since the differential pressure before and after the throttle is large at the moment when the throttle is opened, the amount of air passing through the throttle flows at once and gradually falls to a steady state. The throttle passing air amount Gth in the state can be expressed by this ratio A / ADELAY, and in the steady operation state, this value becomes "1" as shown in the lower graph of FIG. Below, this ratio is
OA ".

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

In this way, the intake air amount Gc can be obtained based on the throttle passing air amount Gth by calculating the chamber filling air amount Gb from 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 by the equation (8).
Further, when the equations 9 and 10 are expressed in the form of transfer function,
Equation 11 is derived. As shown in the equation (11), the intake air amount Gc can be obtained from the primary delay value of the throttle passing air amount Gth.

[0039]

(Equation 8)

[0040]

[Equation 9]

[0041]

[Equation 10]

[0042]

[Equation 11]

Therefore, such a series of arithmetic processing is shown as a block diagram in FIG. Since the intake air amount Gc can be treated in the same manner as the fuel injection amount, the intake air amount is treated as the fuel injection amount in the following block diagrams and the like for convenience. Further, in the figure, "(1-
B) / (z-B) "is a transfer function of a discrete system and means a first-order delay.

Therefore, under certain conditions during steady operation (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 Here, the calculation process performed by the intake air amount estimation device in the present embodiment is
A block diagram is shown in FIG.

As described above, when the engine operating condition is the steady state, the influence of the detected noise is removed,
It is necessary to stabilize the intake air amount estimation processing operation. Therefore, in the estimation device according to the present embodiment, the steady state determination unit 100 that determines whether the operating state of the engine is the steady state and the steady state determination unit 100 determines that the operating state of the engine is the steady state. In this case, a conversion unit 101 for converting the value of the effective opening area ratio RATIO-A of the throttle into a predetermined value is provided.

The operation of the intake air amount estimating device will be described below with reference to the main flowchart of FIG. It should be noted that this flowchart is activated at each TDC position.

First, the engine speed N detected by each sensor
e, intake pressure Pb, throttle opening θTH, atmospheric pressure Pa, engine cooling water temperature Tw, etc. are read (S10). Further, as the throttle opening θTH, the throttle fully closed opening in the idle operation state is learned and the value is used.

Next, it is determined whether the engine is cranking (starting) (S20). When it is determined that the cranking is being performed (“YES” in S20), a predetermined table (not shown) is searched from the water temperature Tw to calculate the fuel injection amount Ticr during cranking (S21), and then the starting mode. The fuel injection amount Tout is determined based on the equation (the description is omitted) (S22).

On the other hand, if it is determined in S20 that cranking is not in progress ("NO" in S20), then it is determined whether or not fuel cut is in progress (S30). If it is judged to be a fuel cut (in S30, "YE
S "), the fuel injection amount Tout is set to zero (S31).

If "NO" is determined in S30,
ROM 5 based on the engine speed Ne and the intake pressure Pb
The map stored in FIG. 8 (FIG. 6) is searched, and the fuel injection amount Timap in the steady operation state (intake air amount G in the steady operation state G
c ′) is obtained (S40). Searched fuel injection amount Timap
After that, pressure correction and the like are appropriately added as necessary (not shown).

Next, the throttle opening θTH read in S10 and the first-order lag transfer function "(1-B) / (z-
B) ”, the first-order delay value θTH-D of the throttle opening is calculated (S50). Next, 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 primary delay value θTH-D of the throttle opening and the intake pressure Pb
And the first-order delay value ADELA of the effective opening area of the throttle
Y is calculated (S70).

Next, "RATIO-A" is calculated from the expression RATIO-A = (A + ABYPASS) / (A + ABYPASS) DELAY (S80). It should be noted that ABYPASS means the amount of air (indicated as “lift amount” in FIG. 12) that is taken into each cylinder combustion chamber via the bypass 32 or the like without passing through the throttle valve, and is accurately the intake air. Since it is necessary to consider this air amount in order to determine the amount, the calculation is performed in consideration of this air amount. Specifically, a value corresponding to this air amount is converted into a throttle opening ABYPASS in accordance with a predetermined characteristic and added to the effective opening area A, and the sum (A + ABYPASS) and its first-order lag are approximated. Find the ratio with the value "(A + ABYPASS) DELAY" and call it RATIO-A.

In this way, as a result of adding 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 impact is small.

Subsequently, it is determined whether the operating state of this engine is a steady state (S90). Here, the specific determination method of this steady state is shown in the flowchart of FIG. First, let θTH (k) be the throttle opening obtained at this timing synchronized with TDC, and let θTH (k-1) be the throttle opening obtained at the previous timing.
By calculating (k) -θTH (k-1), the change amount ΔθTH of the throttle opening θTH during this period is obtained (S9).
1). Next, if the absolute value of the calculated change amount ΔθTH is within the predetermined steady-state determination value ΔθCHK, it is determined that the operating state of this engine is the steady state, and the steady-state determination value ΔθCHK
If the value exceeds, the operating state of this engine is determined to be in a transient state (S92). The throttle opening θ
Since the relationship between TH and the intake air amount Gc is as shown in FIG. 17, the steady-state judgment value ΔθCHK is based on this characteristic.
For example, it is desirable to set it to about 0.5 deg on the low opening side, and in addition, it is desirable to set it individually according to the throttle opening θTH as shown in the graph of FIG.
In this setting, the value of the steady determination value ΔθCHK for each throttle opening θTH is stored in advance in the ROM 58 or the like, and the value of the steady determination value ΔθCHK is read according to the throttle opening θTH at that time.

Then, when it is determined that the operating state of this engine is in a transient state ("NO" in S90), the RATIO-determined in S80 is added to the Timap (Gc ') retrieved in S40.
A is multiplied to calculate a fuel injection amount Tout (Gc) corresponding to the amount of air passing through the throttle (S110).

On the other hand, when it is determined that the operating state of this engine is the steady state ("YES" in S90), the conversion unit 10
In 1, the value of RATIO-A obtained in S80 is replaced with the preset value "1.0" (S100). Then, based on this value, the fuel injection amount Tout (G
Calculate c). In this case, the fuel injection amount Tout (Gc)
Becomes equal to Timap (Gc ').

In this way, the amount of change in throttle opening Δθ
When TH is within a very small range, it is possible to remove the influence of detected noise and other factors by assuming that the engine operating condition is in a steady state and performing arithmetic processing, and stabilize the intake air amount estimation processing operation. be able to.

In the present embodiment, the determination as to whether or not the engine operating condition is in the steady state is made based on the change amount ΔθTH of the throttle opening θTH.
It is also possible to judge whether the operating state of the engine is a steady state.

For example, S90 in the flowchart of FIG.
In, the steady state of the engine may be determined based on the value of the effective opening area ratio RATIO-A of the throttle obtained in S80. In this case, if the value of RATIO-A is "1.00", the value of the effective opening area A of the throttle is equal to its first-order lag value ADELAY, and in this case, the engine operating condition is steady. It can be judged that it is in a state. In addition, considering the influence of engine vibration that causes noise as described above, when the value of RATIO-A falls within the range of 0.95 to 1.05, the operating condition of the engine Can be regarded as a steady state. Therefore, the value of RATIO-A is 0.95
If it is within the range of 1.05, it is determined to be in a steady state (“YES” in S90), and in S100, the value of RATIO-A is newly reset to “1.00”.

In this setting process, the value of RATIO-A can be replaced with the RATIO-A conversion value in accordance with the characteristic determined by the characteristic line 1 shown in FIG.

Although the steady state determination method of the engine illustrated above is a process performed based on the detected throttle opening degree θTH, in addition to this, the intake pressure Pb is also changed. The detection can also determine the operating state of the engine. Specifically, the intake pressure Pb is detected in synchronism with TDC, and the difference (absolute value) between the detection values obtained at the previous and present timings must be within the range of the predetermined steady determination value ΔPbCHK. For example, the operating condition of this engine is judged to be steady.

It is desirable that the steady-state determination value ΔPbCHK is also set in advance corresponding to each engine speed Ne, as in the above (FIG. 18). For example, in idle state,
If the fluctuation of the intake pressure Pb is within the range of ± 20 mmHg, it is judged that the operating state of the engine is the steady state (S90
Then, the processing for newly resetting the value of RATIO-A to "1.00" is performed (S100).

Even in this determination processing, the value of the steady determination value ΔPbCHK with respect to the engine speed Ne is previously set to RO.
It is desirable to store it in M58 or the like and read the value of the steady determination value ΔPbCHK according to the engine speed Ne at that time during the determination process.

In the embodiment described above, the fuel injection amount Tim
Although an example in which ap is mapped in advance has been shown, instead of this, the intake air amount Gc ′ in the steady operation state is mapped,
It may be stored in the ROM 58.

Further, in the present embodiment, an example in which the conversion unit 101 converts the value of the effective opening area ratio RATIO-A of the throttle to "1.00" when the operating state is the steady state is shown. For example, “1.0
It is also possible to set it to an arbitrary value in the vicinity of 1.00 such as "2".

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

[0067]

As described above, in the intake air amount estimating apparatus for an internal combustion engine according to the first aspect of the present invention, conversion is performed during the period when the operating state of the internal combustion engine is considered to be the steady state by the steady state determining means. By the effective opening area ratio R
We adopted a configuration that converts the value of ATIO-A to a predetermined value.
Therefore, the effective aperture area ratio RAT
Even if the IO-A value fluctuates slightly, the effective opening area ratio RATIO-A is maintained at a constant value during the period considered to be in a steady state, so the estimation process of the intake air amount should be stabilized. You can

In the intake air amount estimating apparatus for an internal combustion engine according to claim 2, the steady state determining means determines that the steady state is established if the amount of change in the throttle opening is within a predetermined range. . Therefore, even if the throttle opening is slightly changed and detected due to the vibration of the engine being applied to the throttle body, etc., even if it is in a steady state, this fluctuation should be within the predetermined fluctuation range. For example, assuming that it is in a steady state, subsequent estimation processing can be performed. Therefore, the estimation process of the intake air amount in the steady state can be stabilized.

Further, in the intake air amount estimating apparatus for the internal combustion engine according to the third aspect, the value of the first effective opening area A of the throttle is the second effective opening area ADELAY which becomes the first-order lag value.
And the effective opening area ratio RATIO
When the value of -A is within the predetermined range near 1, the steady state determination means determines the steady state. Therefore,
Since the first effective opening area A of the throttle and the like are obtained based on the value of the throttle opening, even when the detected throttle opening contains some noise or the like even in the steady state, It is possible to carry out the following estimation process by regarding the steady state.

Further, in the intake air amount estimating apparatus for the internal combustion engine according to the fourth aspect, it is possible to judge whether or not the operating state is the steady state by the change amount of the chamber pressure Pb. Therefore, the change amount of the chamber pressure Pb. A configuration including a steady state determination means for determining the steady state based on the above is adopted. Therefore,
If the amount of change in the chamber pressure Pb is within a predetermined range,
It can be judged as a steady state regardless of the throttle opening, and even if the detected throttle opening contains noise etc.,
The subsequent estimation process can be performed assuming that the steady state is achieved. As a result, it is possible to stabilize the estimation process of the intake air amount in the steady state.

[Brief description of drawings]

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

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

FIG. 3 is an explanatory diagram showing a fluid dynamics model adopted in this embodiment.

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

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

FIG. 6 is an explanatory diagram showing map characteristics 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 the present embodiment.

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

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

FIG. 12 is a block diagram showing a calculation process of a fuel injection amount (intake air amount).

FIG. 13 is a main flowchart showing a process of calculating a fuel injection amount (intake air amount).

14 is a flowchart showing S in the main flowchart of FIG.
It is a flowchart which shows the determination process implemented in 90.

FIG. 15 is a graph showing a relationship between a throttle opening and a steady-state determination value.

FIG. 16 is a graph used when converting a value of RATIO-A.

FIG. 17 is a graph showing the relationship between throttle opening and intake air amount.

FIG. 18 is a graph showing the relationship between intake pressure and a steady-state determination value.

[Explanation of symbols]

10 ... Internal combustion engine, 12 ... Intake passage, 16 ... Throttle valve,
Reference numeral 20 ... Intake manifold, 34 ... Crank angle sensor, 36 ... Throttle opening sensor, 38 ... Intake pressure sensor, 100 ... Steady state determination unit, 101 ... Conversion unit.

Claims (4)

[Claims] 1. A first means for detecting an operating state of an internal combustion engine including an engine speed Ne, a throttle opening θTH and a chamber pressure Pb, and at least the engine speed detected by the first means. A second method for obtaining 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 the first effective opening area A of the throttle based on at least the throttle opening θTH and the chamber pressure Pb detected by the first means; A fourth delay means for obtaining a first-order lag value of the first effective opening area A and setting the value as a second effective opening area ADELAY of the throttle, and a ratio of the first effective opening area A to the second effective opening area ADELAY. Based on the effective opening area ratio RATIO-A of the throttle obtained by the fifth means and the effective opening area ratio RATIO-A of the throttle, the intake air amount is obtained. In the intake air amount estimating apparatus for an internal combustion engine, which is provided with a sixth means for determining the actual intake air amount Gc as Gc = Gc 'x RATIO-A by correcting Gc', the operating state of the internal combustion engine is If it is within the specified range,
If the operating state of this internal combustion engine is determined to be a steady state, and the steady state determining means determines that the operating state of this internal combustion engine is a steady state, the effective opening area ratio RATIO of the throttle -Convert the value of A to a predetermined value,
An intake air amount estimating apparatus for an internal combustion engine, comprising: a converting unit that supplies this value to the sixth unit. 2. The steady state determining means determines that the operating state of the internal combustion engine is a steady state when the amount of change in the throttle opening within a predetermined time is within a predetermined range. Claim 1 characterized by the above-mentioned.
An intake air amount estimation device for an internal combustion engine as described above. 3. The operating condition of the internal combustion engine, wherein the steady state judging means determines that the value of the effective opening area ratio RATIO-A of the throttle obtained by the fifth means is within a predetermined range near 1. The intake air amount estimating apparatus for an internal combustion engine according to claim 1, wherein is determined to be a steady state. 4. The steady state determining means determines that the operating state of the internal combustion engine is a steady state when the amount of change in the chamber internal pressure Pb within a predetermined time is within a predetermined range. The intake air amount estimating apparatus for an internal combustion engine according to claim 1, wherein