JP2000265899A - Intake air quantity estimating device for internal combustion engine and fuel supply control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intake air quantity estimating device for an internal combustion engine capable of exactly estimating intake air quantity by considering the state of residual gas within a combustion chamber at the time of a transition and to provide a fuel supply control device capable of sufficiently suppressing influence on emission and an engine output. SOLUTION: By charging efficiency KTPt (S130) corrected based on an actual combustion chamber temperature Tr and a combustion chamber temperature T at normal time and intake pressure PM, intake air quantity (K1×PM×KTPt) is determined (S150). Therefore, a temperature state of residual gas within a combustion chamber of an engine can be reflected on intake air quantity and exact intake air quantity can be determined also at the time of a transition. Therefore, sufficiently exact fuel injection quantity TAU corresponding to actual intake air quantity can be calculated also at the time of the transition (S150).

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 device for an internal combustion engine and a fuel supply control device for the internal combustion engine.

[0002]

2. Description of the Related Art As a fuel supply control method for setting a fuel amount to be supplied to an internal combustion engine, there is a method of calculating a supplied fuel amount based on an intake pressure downstream of a throttle valve, a so-called D jetronic method.

In this fuel supply control system, there is a tendency that a difference occurs between the intake air amount estimated by calculation and the actual intake air amount during a transition when the engine speed, the engine load, and the like change. For this reason, there is a possibility that the amount of supplied fuel may be excessive or insufficient.

As a technique for accurately estimating the amount of intake air even in a transient state, for example, there is a technique disclosed in Japanese Patent Application Laid-Open No. 8-144833. In this prior art, the amount of intake air is calculated as follows so that the fuel supply amount can be accurately obtained even during a transition.

That is, the air density in the cylinder at the time of the intake stroke is calculated from the equation of the state of air based on the intake pressure and the intake temperature. Next, the theoretical intake air amount into the combustion chamber per intake stroke is calculated from the product of the air density and the stroke volume.
Next, the intake loss amount and the volume efficiency are obtained from the respective maps using the engine speed as a parameter, and the actual intake air amount is estimated from the theoretical intake air amount, the intake loss amount and the volume efficiency values. .

Further, in this prior art, when the intake air temperature exceeds the critical temperature, the intake air temperature is fixed and the theoretical intake air amount is determined to prevent the fuel supply amount from being set too low.

[0007]

However, during the transition, there is an error in the amount of intake air which cannot be estimated by the above-mentioned prior art calculation. This is because the temperature of the residual gas present in the combustion chamber after the exhaust stroke exhibits a temperature different from the temperature in the steady state during the transition even if the operation state of the internal combustion engine such as the engine speed and the engine load is the same. Because it is.

[0008] For example, during acceleration transient, the temperature of the residual gas is lower than the steady state temperature for the same operating state of the internal combustion engine because the temperature in the combustion chamber is in the process of rising. For this reason, the volumetric efficiency obtained from the above-mentioned map is lower than the actual volumetric efficiency, and the intake air amount is estimated to be smaller than the actual volumetric efficiency. Therefore, the fuel supply amount calculated based on the volumetric efficiency of this map becomes too small, and the air-fuel ratio becomes leaner than the required concentration.

[0009] Further, during the deceleration transition, since the temperature in the combustion chamber is in the process of falling, the actual temperature of the residual gas becomes
It is higher than the steady state temperature for the same operating condition of the internal combustion engine. For this reason, the volumetric efficiency obtained from the above-mentioned map is higher than the actual volumetric efficiency, and the intake air amount is estimated to be larger than the actual volumetric efficiency. Therefore, the fuel supply amount calculated based on the volumetric efficiency of this map becomes excessive, and the air-fuel ratio becomes richer than the required concentration.

[0010] Therefore, in the prior art, in the estimation calculation of the intake air amount in the transient state, there is a part that cannot be sufficiently dealt with yet, and the air-fuel ratio is disturbed and the influence on the emission and the engine output is sufficiently suppressed. Can not.

The present invention provides an intake air amount estimating apparatus for an internal combustion engine capable of accurately estimating an intake air amount by taking into account the state of residual gas in a combustion chamber at the time of transition, and an effect on emission and engine output. It is an object of the present invention to provide a fuel supply control device capable of sufficiently suppressing the fuel supply.

[0012]

According to a first aspect of the present invention, there is provided an internal combustion engine intake air amount estimating apparatus for calculating an intake air amount to an internal combustion engine based on an intake pressure. , The intake air amount calculated based on the intake pressure,
The intake air amount of the internal combustion engine is estimated by making a correction according to the actual combustion chamber temperature and the steady-state combustion chamber temperature corresponding to the operating state of the internal combustion engine.

Here, the intake air amount obtained based on the intake pressure is further corrected according to the actual combustion chamber temperature and the steady-state combustion chamber temperature corresponding to the operating state of the internal combustion engine. In the related art, the intake air amount is determined based on the intake pressure, assuming a steady-state temperature in the combustion chamber. However, in the present invention, the temperature of the combustion chamber at the time of steady state is
Further, referring to the actual combustion chamber temperature, the intake air amount is estimated by correcting the intake air amount based on the relationship between the two temperatures.

Therefore, the temperature state of the residual gas in the combustion chamber can be reflected on the intake air amount calculated based on the intake pressure, and it is possible to accurately estimate the intake air amount even during a transition. Become. Therefore, if the fuel supply amount is set using the data of the intake air amount, it is possible to sufficiently suppress the influence on the emission and the engine output during the transition.

According to a second aspect of the present invention, there is provided an intake air amount estimating apparatus for an internal combustion engine, comprising: an intake pressure detecting means for detecting an intake pressure of the internal combustion engine; a combustion chamber temperature detecting means for detecting an actual combustion chamber temperature of the internal combustion engine; An internal combustion engine operating state detecting means for detecting an operating state of the engine; and a constant for obtaining a temperature in the combustion chamber in a steady state in the operating state based on the operating state of the internal combustion engine detected by the internal combustion engine operating state detecting means. Constant combustion chamber temperature calculation means, steady-state combustion chamber temperature determined by the steady-state combustion chamber temperature calculation means, actual combustion chamber temperature detected by the combustion chamber temperature detection means, and the intake pressure detection means And an intake air amount estimating means for estimating an intake air amount of the internal combustion engine based on the intake pressure detected by the control unit.

The steady-state combustion chamber temperature calculating means obtains a steady-state combustion chamber temperature in this operating state based on the operating state of the internal combustion engine detected by the internal combustion engine operating state detecting means. Based on the steady-state temperature in the combustion chamber determined in this way, the actual combustion chamber temperature detected by the combustion chamber temperature detecting means, and the intake pressure detected by the intake pressure detecting means, The estimating means estimates an intake air amount of the internal combustion engine.

Therefore, as in the case of the first aspect,
The temperature state of the residual gas in the combustion chamber can be reflected on the intake air amount calculated based on the intake pressure, and it is possible to accurately estimate the intake air amount even during a transition. Therefore, if the fuel supply amount is set using the data of the intake air amount, it is possible to sufficiently suppress the influence on the emission and the engine output during the transition.

According to a third aspect of the present invention, in the intake air amount estimating device for an internal combustion engine according to the second aspect, the internal combustion engine operating state detecting means detects the load and the rotation speed of the internal combustion engine by operating the internal combustion engine. It is characterized in that it is detected as a state.

More specifically, the internal combustion engine operating state detecting means detects the load and rotation speed of the internal combustion engine as the operating state of the internal combustion engine. The room temperature can be determined appropriately. For this reason, in addition to the operation and effect described in claim 2, the intake air amount of the internal combustion engine in the transient state can be further increased by the intake air amount estimation means by using the steady-state combustion chamber temperature obtained in this manner. It will be possible to estimate accurately.

According to a fourth aspect of the present invention, there is provided the internal combustion engine intake air amount estimating apparatus according to the third aspect, wherein the load of the internal combustion engine is an intake pressure or a throttle valve opening.

As described above, the intake pressure or the throttle valve opening can be used as the load, and the operation and effect as described in claim 3 are produced. According to a fifth aspect of the present invention, in the intake air amount estimating device for an internal combustion engine according to any one of the second to fourth aspects, the combustion chamber temperature detecting means is configured to calculate the actual combustion chamber temperature already calculated and the steady-state combustion. A new actual combustion chamber temperature is calculated based on the steady-state combustion chamber temperature obtained by the indoor temperature calculation means.

The combustion chamber temperature detecting means may directly detect the actual combustion chamber temperature by, for example, providing a temperature sensor or the like in the combustion chamber. Instead of directly measuring the combustion chamber temperature, a new actual combustion chamber temperature is calculated based on the already calculated actual combustion chamber temperature and the steady-state combustion chamber temperature obtained by the steady-state combustion chamber temperature calculating means. Is calculated.

The steady-state combustion chamber temperature obtained by the steady-state combustion chamber temperature calculation means is a direction in which the actual combustion chamber temperature changes, and represents a temperature that is finally stabilized with the passage of time. For this reason, especially, the actual combustion chamber temperature during the transition always changes toward the steady-state combustion chamber temperature corresponding to the operating state of the internal combustion engine at that time. The degree of this change is determined by the relationship between the actual combustion chamber temperature and the steady-state combustion chamber temperature. Therefore, the behavior of the actual combustion chamber temperature can be tracked from the relationship between the actual combustion chamber temperature and the steady-state combustion chamber temperature, and the actual combustion chamber temperature can be continuously detected.

In this way, in addition to the functions and effects of any one of claims 2 to 4, the temperature of the actual combustion chamber can be easily detected with a simple configuration without attaching a temperature sensor or the like to the combustion chamber. It can be used for estimating the intake air amount during transition.

According to a sixth aspect of the present invention, there is provided a fuel supply control apparatus for an internal combustion engine which calculates a fuel supply amount to the internal combustion engine based on an intake pressure. And controlling the amount of fuel supplied to the internal combustion engine based on the steady-state temperature in the combustion chamber corresponding to the operating state of the internal combustion engine.

Here, the fuel supply amount is controlled based on the intake pressure, the actual combustion chamber temperature, and the steady-state combustion chamber temperature. In the related art, the fuel supply amount is determined based on the intake pressure without considering the actual combustion chamber temperature, assuming that the fuel supply amount exists under the steady-state combustion chamber temperature.

However, in the present invention, the actual combustion chamber temperature is further referred to together with the steady-state combustion chamber temperature corresponding to the operating state of the internal combustion engine. Therefore, the temperature state of the residual gas in the combustion chamber can be reflected in the calculation of the fuel supply amount, and a sufficiently accurate fuel supply amount corresponding to the actual intake air amount can be calculated even in a transient state. Becomes Therefore, it is possible to sufficiently suppress the influence on the emission and the engine output during the transition.

According to a seventh aspect of the present invention, there is provided a fuel supply control device for an internal combustion engine, comprising: an intake pressure detecting means for detecting an intake pressure of the internal combustion engine;
Combustion chamber temperature detecting means for detecting the actual combustion chamber temperature of the internal combustion engine, internal combustion engine operating state detecting means for detecting the operating state of the internal combustion engine, and operating state of the internal combustion engine detected by the internal combustion engine operating state detecting means A steady-state combustion chamber temperature calculating means for calculating a steady-state combustion chamber temperature in the operating state based on the operating state; a steady-state combustion chamber temperature calculated by the steady-state combustion chamber temperature calculating means; Fuel supply amount control means for controlling the fuel supply amount to the internal combustion engine based on the actual combustion chamber temperature detected by the detection means and the intake pressure detected by the intake pressure detection means. Features.

The steady-state combustion chamber temperature calculating means obtains a steady-state combustion chamber temperature in this operating state based on the operating state of the internal combustion engine detected by the internal combustion engine operating state detecting means. The fuel supply amount is determined based on the steady-state combustion chamber temperature obtained in this manner, the actual combustion chamber temperature detected by the combustion chamber temperature detection means, and the intake pressure detected by the intake pressure detection means. The control means controls a fuel supply amount to the internal combustion engine.

For this reason, as in the case of claim 6,
The fuel supply amount can be obtained by reflecting the temperature state of the residual gas in the combustion chamber, and a sufficiently accurate fuel supply amount corresponding to the actual intake air amount can be obtained even during a transition. Therefore, it is possible to sufficiently suppress the influence on the emission and the engine output during the transition.

The fuel supply control device for an internal combustion engine according to the eighth aspect of the present invention is the fuel supply control device for an internal combustion engine according to the seventh aspect, wherein the internal combustion engine operating state detecting means detects the load and the rotation speed of the internal combustion engine. Is detected.

More specifically, the operating state detecting means for the internal combustion engine detects the load and rotation speed of the internal combustion engine as the operating state of the internal combustion engine. The room temperature can be determined appropriately. For this reason, in addition to the operation and effect described in claim 7, the fuel supply amount control means further increases the fuel supply amount to the internal combustion engine in the transient state by using the steady-state combustion chamber temperature obtained in this manner. It becomes possible to control accurately.

According to a ninth aspect of the present invention, in the fuel supply control device for an internal combustion engine according to the eighth aspect, the load of the internal combustion engine is an intake pressure or a throttle valve opening.

As described above, the intake pressure or the throttle valve opening can be used as the load, and the operation and effect described in the eighth aspect are produced. According to a tenth aspect of the present invention, in the fuel supply control device for an internal combustion engine according to any one of the seventh to ninth aspects, the combustion chamber temperature detecting means includes an actual combustion chamber temperature already calculated and the steady-state combustion chamber. A new actual combustion chamber temperature is calculated based on the steady-state combustion chamber temperature obtained by the temperature calculation means.

As in the case of the fifth aspect, the combustion chamber temperature detecting means may directly detect the actual combustion chamber temperature by, for example, providing a temperature sensor or the like in the combustion chamber. In the tenth aspect, instead of directly measuring the temperature in the combustion chamber, the temperature in the combustion chamber is calculated based on the actual combustion chamber temperature already calculated and the steady-state combustion chamber temperature obtained by the steady-state combustion chamber temperature calculating means. Thus, a new actual combustion chamber temperature is calculated.

According to the mechanism described in claim 5,
The degree of change in the actual combustion chamber temperature during the transition is affected by the relationship between the actual combustion chamber temperature and the steady-state combustion chamber temperature. Therefore, the behavior of the actual combustion chamber temperature can be tracked from the difference between the actual combustion chamber temperature and the steady-state combustion chamber temperature, and the actual combustion chamber temperature can be continuously detected.

In this way, in addition to the functions and effects of any one of claims 7 to 9, the temperature of the actual combustion chamber can be easily detected with a simple configuration without mounting a temperature sensor or the like on the combustion chamber. In addition, accurate control of the fuel supply amount at the time of transition can be performed.

[0038]

[First Embodiment] FIG. 1 is a block diagram showing a schematic configuration of a fuel injection amount control device for an internal combustion engine to which the above-described invention is applied. A gasoline engine 2 is used as an internal combustion engine, and is exemplified as one that is mounted on an automobile and drives the automobile.

The intake path 4 of the gasoline engine 2 has a throttle valve 6 for adjusting the amount of air taken into the combustion chamber 2c.
Is provided. The opening of the throttle valve 6 is adjusted in response to the operation amount of an accelerator pedal (not shown) by the driver directly or indirectly through an electric signal. Rotary shaft 6a of throttle valve 6
At one end, a throttle valve opening sensor 8 is attached. The throttle valve opening sensor 8 detects the opening of the throttle valve 6 and outputs an opening signal to the ECU.
(Electronic control unit).

In the surge tank 4a downstream of the throttle valve 6, an intake pressure detecting port 12a is provided, and is connected to the intake pressure sensor 12 via a pressure guiding pipe 12b. The intake pressure sensor 12 outputs to the ECU 10 a pressure signal corresponding to the pressure (absolute pressure) in the intake passage 4 acting via the pressure guiding pipe 12b.

The intake passage 4 is provided with a fuel injection valve 16 for injecting pressurized fuel toward the intake port 14 of each cylinder of the gasoline engine 2. Fuel is supplied to the fuel injection valve 16 from the fuel tank 17 by a fuel pump 17a. The fuel injection amount (corresponding to the fuel supply amount) is controlled by controlling the valve opening period of the fuel injection valve 16 by the ECU 10.

An air-fuel ratio sensor 20 is provided at an exhaust junction of the exhaust manifold 18 which forms a part of the exhaust path of the gasoline engine 2. The air-fuel ratio sensor 20 outputs a signal corresponding to the oxygen concentration in the exhaust to the ECU 10.

Cylinder block 2 of gasoline engine 2
A is provided with a water temperature sensor 22 for detecting the temperature of the cooling water in the cooling water passage 2b. Water temperature sensor 22
Outputs a signal corresponding to the temperature of the cooling water to the ECU 10.

A distributor (not shown) includes a pulse generator 24 for detecting the rotation speed of the gasoline engine 2 and a reference position sensor 26 for detecting the crank angle.
Are provided. The pulse generator 24 and the reference position sensor 26 convert the pulse signal and the reference position signal into EC signals.
Output to U10.

The ECU 10 is configured as a microcomputer system. That is, the ECU 10 includes a CPU 10b, a memory 10c such as a ROM and a RAM, an input interface 10d, and an output interface 10e, with the bus 10a at the center.

The aforementioned throttle valve opening sensor 8,
Intake pressure sensor 12, air-fuel ratio sensor 20, water temperature sensor 2
2. Various sensors such as a pulse generator 24, a reference position sensor 26, an intake air temperature sensor (not shown), and a vehicle speed sensor (not shown) are connected to the input interface 10d.
The ECU 10 fetches signal contents via the input interface 10d in order to process output data of these various sensors.

Further, the ECU 10 outputs a signal for controlling the opening of the fuel injection valve 16 to the fuel injection valve 16 via the output interface 10e as necessary. Next, the fuel injection amount control executed by the ECU 10 in the first embodiment will be described. FIG. 2 shows a flowchart of the fuel injection amount control process. This process is repeatedly executed for each crank rotation angle defined by the ECU 10. Hereinafter, individual processing steps in the flowchart are represented by “S〜”.

When the fuel injection amount control process shown in FIG. 2 starts, first, the latest engine speed obtained from the data of the intake pressure PM from the intake pressure sensor 12 and the pulse of the pulse generator 24 and stored in the memory 10c. The data of several NEs is read (S110).

Next, using the read values of the intake pressure PM and the engine speed NE, the corresponding value of the charging efficiency KTP is read from the two-dimensional map (FIG. 3) stored in the memory 10c (S120). ).

The charging efficiency KTP represents the ratio between the intake air weight per one engine revolution and the intake pressure PM. This filling efficiency KTP is used in an equation for calculating the fuel injection amount TAU after being corrected and converted into a new filling efficiency KTPt, which will be described later. In the first embodiment, the intake pressure PM and the engine speed NE are adjusted to various values using the same kind of gasoline engine in the first embodiment. Is obtained by actually measuring the intake air weight.

Next, the filling efficiency KTP obtained in step S120 is corrected by the following equation 1 to obtain a new filling efficiency KTPt (S130).

[0052]

KTPt ← KTP− (1−KTP) · ΔT / T (Equation 1) Here, the steady-state combustion chamber temperature T (absolute temperature) is
This is a value obtained from the load of the engine 2 (here, the intake pressure PM) and the engine speed NE from the two-dimensional map shown in FIG. This map represents the state of the temperature T in the combustion chamber when the intake pressure PM and the engine speed NE are in a steady state, and is data that is actually measured in advance using the same type of engine.

The temperature deviation ΔT is the actual combustion chamber temperature T
It is the difference between r (however, absolute temperature) and the steady-state combustion chamber temperature T, and is expressed by the following equation (2).

[0054]

ΔT ← Tr−T (Equation 2) In addition, the above equation 1 represents the temperature T of the residual gas in the combustion chamber 2c.
This is an equation derived from the fact that the relationship between r and T and the charging efficiency KTPt and KTP can be expressed by the following equation 3.

[0055]

1−KTPt = (1−KTP) × (Tr / T) [Expression 3] By substituting Expression 2 into Expression 3, and obtaining KTPt, Expression 1 is obtained.

The actual combustion chamber temperature Tr represents the actual temperature in the combustion chamber 2c of the engine 2. The data of the actual combustion chamber temperature Tr may be obtained by directly measuring the temperature in the combustion chamber 2c. However, in the first embodiment, the actual combustion chamber temperature Tr estimation shown in FIG. The value repeatedly obtained in the processing is used. The steady-state combustion chamber temperature T and the temperature deviation ΔT also use values repeatedly calculated in the process of FIG.

In the actual combustion chamber temperature Tr estimation process of FIG.
First, based on the temperature deviation ΔT, the intake pressure PM and the engine speed NE already calculated in the previous cycle, the temperature change amount dt corresponding to the response time constant is obtained from the temperature change response time constant map shown in the graph of FIG. It is determined (S170).

Then, as shown in the following equation 4, the temperature change amount dt is added to the actual combustion chamber temperature Tr to obtain a new actual combustion chamber temperature Tr (S180).

[0059]

Next, the intake pressure PM and the engine speed NE are read, and the intake pressure PM is calculated using the two-dimensional map of FIG. 4 as described above.
The steady-state combustion chamber temperature T is determined from the engine speed NE and the engine speed NE (S185). Then, a new temperature deviation ΔT is obtained according to the above equation (S190), and the process ends once.

By repeating such processing periodically, an accurate actual combustion chamber temperature Tr can always be obtained, and a steady-state combustion chamber temperature T and a temperature deviation ΔT can be accurately obtained. Note that, for example, the initial values of the steady-state combustion chamber temperature T and the actual combustion chamber temperature Tr are the water temperature sensor 2
2, the cooling water temperature THW detected is set, and 0 is set as the temperature deviation ΔT.

In step S130 of FIG.
When the calculation of Pt is completed, the fuel injection amount TAU is calculated by the following equation 5 (S150).

[0062]

TAU ← K1 × PM × KTPt × {FAF + KG} + K2 (Equation 5) Here, the coefficient K1 is, for example, a coefficient for converting an intake air amount into a fuel injection amount, and the coefficient K2 is, for example, for example. This is a coefficient for considering the amount of the fuel injected from the fuel injection valve 16 adhered to the wall surface of the intake port 14 and other factors.

Here, the air-fuel ratio feedback coefficient FAF
And the learning value KG are data calculated by the air-fuel ratio feedback control process shown in FIGS. FIG.
4 is a flowchart illustrating an air-fuel ratio feedback coefficient FAF calculation process executed by the ECU 10. This process is executed by interruption every prescribed crank angle. When the process is started, first, it is determined whether a condition for performing the air-fuel ratio feedback control is satisfied (S
200). This condition is, for example, as follows.

(1) Not at the time of starting. (2) The fuel is not being cut. (3) Warm-up has been completed. (For example, cooling water temperature THW ≧
(4 °) (4) The activation of the air-fuel ratio sensor 20 has been completed.

When all of the above conditions (1) to (4) are satisfied, the air-fuel ratio feedback control is permitted,
If any one of the conditions is not satisfied, the air-fuel ratio feedback control is not allowed.

When all the conditions are satisfied (S200
Is "YES") is the output voltage Vo of the air-fuel ratio sensor 20.
x is read (S202), and the reference voltage Vr (for example, 0.
45V) is determined (S204). V
If ox <Vr (“YES” in S204), it is determined that the air-fuel ratio detected based on the exhaust gas is lean, and the air-fuel ratio flag XOX is reset (XOX ← 0) (S2).
06).

Next, it is determined whether or not the air-fuel ratio flag XOX and the state maintaining flag XOXO match (S20).
8). If XOX = XOXO ("YE" in S208)
S "), assuming that the lean state is continued, the air-fuel ratio feedback coefficient FAF is set to the lean integral amount a (a> 0).
The number is increased (S210), and the present process ends once.

On the other hand, if XOX ≠ XOXO (S20
8 ("NO"), the air-fuel ratio feedback coefficient FAF is increased by the lean skip amount A (A> 0) assuming that the rich state has been inverted to the lean state (S212). Note that the lean skip amount A is set to a value sufficiently larger than the lean integral amount a. Then, the status maintaining flag XOXO is reset (XOXO ← 0) (S21).
4) This process is temporarily ended.

If it is determined in step 204 that Vox ≧ Vr ("NO" in S204), it is determined that the air-fuel ratio of the exhaust gas is rich, and the air-fuel ratio flag XOX is set (XO).
X ← 1) is performed (S216). Next, it is determined whether or not the air-fuel ratio flag XOX and the state maintaining flag XOXO match (S218).

If XOX = XOXO ("YES" in S218), it is determined that the rich state is continuing.
The air-fuel ratio feedback coefficient FAF is set to the rich integration amount b (b
> 0) is decreased (S220), and this process is temporarily terminated.

If XOX ≠ XOXO (“NO” in S218), the air-fuel ratio feedback coefficient FAF is reduced by the rich skip amount B (B> 0) assuming that the lean state has been inverted to the rich state (S222). Note that the rich skip amount B is set to a value sufficiently larger than the rich integration amount b.

Next, the state maintaining flag XOXO is set (X
OXO ← 1) (S224), and this process ends once. If even one of the conditions is not satisfied in step 200 ("NO" in S200), the air-fuel ratio feedback coefficient FAF is set to "1.0" (S22).
6) This process is temporarily ended.

The air-fuel ratio feedback coefficient FAF calculation processing is executed as described above, and the air-fuel ratio feedback coefficient FAF for adjusting the actual air-fuel ratio to the target air-fuel ratio is repeatedly obtained.

FIG. 8 shows the air-fuel ratio feedback coefficient FAF.
8 is a flowchart of the average value FAFAV calculation processing, which is executed following the air-fuel ratio feedback coefficient FAF calculation processing of FIG.

In this process, first, the average value F of the air-fuel ratio feedback coefficient FAF and the immediately preceding value FAFB is calculated by the following equation (6).
AFAV is calculated (S302).

[0076]

[Expression 6] FAFAV ← (FAFB + FAF) / 2 [Equation 6] Then, in preparation for the next calculation, the value of FAFB is replaced with the current value of the air-fuel ratio feedback coefficient FAF (S3).
04). Thus, the present process is temporarily terminated.

FIG. 9 is a flowchart of an air-fuel ratio feedback coefficient FAF learning process for learning the air-fuel ratio feedback coefficient FAF. This processing is also interrupted at every specified crank angle.

When this processing is started, it is first determined whether or not a learning condition is satisfied (S405). The learning condition may include, for example, the condition described in step S200. Other than the condition of step S200,
The condition under which the air-fuel ratio feedback control state is stable depends on whether a sufficient time has elapsed since the operating range of the engine 2 has changed.

If the learning condition of the air-fuel ratio feedback coefficient FAF is satisfied ("YES" in S405), the aforementioned average value FAFAV of the air-fuel ratio feedback coefficient FAF is obtained.
Is smaller than “0.98” (S41).
0). If FAFAV <0.98 ("Y" in S410
ES "), the learned value K of the air-fuel ratio feedback coefficient FAF
G is reduced by the amount of change β (S420), and this process is once ended.

If FAFAV ≧ 0.98 (S410)
It is determined whether the average value FAFAV is greater than “1.02” (S430). FAFAV> 1.
If it is 02 ("YES" in S430), the learning value KG is increased by the fluctuation amount β (S440), and the present process is ended once.

If 0.98 ≦ FAFAV ≦ 1.02 (“NO” in S410, “NO” in S430), this process is temporarily terminated while the learning value KG is maintained. When the power of the ECU 10 is turned on, the learning value K
“0.00” is initially set as G.

Using the air-fuel ratio feedback coefficient FAF and the learning value KG obtained as described above, the fuel injection amount TAU is calculated by the above-described equation 5, and then the fuel injection amount TAU is calculated.
A down counter (ECU) for setting the fuel injection time for the AU
10 (provided within 10) (S160),
This process ends once.

Thereafter, the above-described processing is repeated, so that the fuel injection valve 1 is determined based on the fuel injection amount TAU.
From 6, an appropriate amount of fuel is injected. In the first embodiment described above, the intake pressure sensor 12 corresponds to intake pressure detecting means, and the intake pressure sensor 12 and the pulse generator 24 correspond to internal combustion engine operating state detecting means.

In the actual combustion chamber temperature Tr estimation process of FIG.
Steps S170, S180, and S190 correspond to processing as a combustion chamber temperature detecting means, and step S185 corresponds to processing as a steady-state combustion chamber temperature detecting means.
The fuel injection amount control process corresponds to a process as fuel supply amount control means. Also, in FIG. 2, step S110
-K1 × P in steps S130 and S150.
The calculation part of “M × KTPt” corresponds to the intake air amount estimating means.

According to the first embodiment described above, the following effects can be obtained. (I). In the first embodiment, based on the intake pressure PM and the corrected charging efficiency KTPt, the intake air amount (K1 ×
PM × KTPt). This filling efficiency KTPt
Is the temperature in the combustion chamber 2c of the engine 2 (actual combustion chamber temperature)
It is corrected based on Tr and the temperature T of the combustion chamber in a steady state.

Therefore, it is possible to obtain an intake air amount in consideration of the temperature state of the residual gas in the combustion chamber 2c of the engine 2, and it is possible to obtain an accurate intake air amount even in a transient state. Therefore, it is possible to calculate a sufficiently accurate fuel injection amount TAU corresponding to the actual intake air amount. Therefore, even during a transition, the influence on the emission of the engine 2, the engine output, and the like can be sufficiently suppressed.

For example, as shown in the timing chart of FIG. 10, at time P, the driver opens the throttle valve 6 and performs an acceleration operation on the engine 2 which has been in a steady operation before time P. In the state, the intake pressure PM immediately rises. For this reason, the temperature T in the combustion chamber in a steady state rises almost stepwise as shown by a broken line.

However, the actual combustion chamber temperature Tr rises slowly. Therefore, the state of T> Tr continues for a while. As long as T> Tr, the intake air amount (K1 × PM × KTP) calculated on the assumption that the temperature in the combustion chamber 2c is at the steady-state combustion chamber temperature T, as in the related art, is indicated by a broken line. Which is smaller than the actual intake air amount indicated by the solid line. For this reason, the fuel injection amount TAU calculated using the intake air amount thus calculated becomes smaller than the required amount, and the air-fuel ratio A / F largely changes to the lean side as shown by the dotted line. .

At time Q, when the driver returns the throttle valve 6 to perform a deceleration operation, and a transient state occurs,
Immediately, the intake pressure PM decreases. For this reason, the temperature T in the combustion chamber in a steady state decreases almost stepwise as shown by a broken line.

However, the actual combustion chamber temperature Tr decreases slowly. Therefore, the state of T <Tr continues for a while. While T <Tr, as in the conventional case, the intake air amount (K1 × PM × KTP) calculated on the assumption that the temperature in the combustion chamber 2c is at the steady-state combustion chamber temperature T is indicated by a broken line. Which is larger than the actual intake air amount indicated by the solid line. Therefore, the fuel injection amount TAU calculated using the intake air amount thus calculated becomes larger than a required amount, and the air-fuel ratio A / F largely changes to the rich side as shown by the dotted line. .

In particular, during the transition due to the deceleration operation, the amount of intake air is in the direction of decreasing, so that the influence of errors appearing in the air-fuel ratio A / F becomes large. However, in the first embodiment, as described above, since the actual combustion chamber temperature Tr is accurately captured and reflected in the calculation of the intake air amount, the fuel injection amount TAU is adjusted to the actual intake air amount. It can be. Therefore, as shown by the solid line, the turbulence of the air-fuel ratio A / F can be sufficiently suppressed both during the acceleration operation and during the deceleration operation. Therefore, the above-described effects can be produced.

(B). The intake pressure PM and the engine speed NE are taken as the operating state of the engine 2, and the temperature T in the combustion chamber in a steady state is obtained. Therefore, the combustion chamber temperature T when the engine 2 is in a steady state can be determined appropriately. By using the appropriate steady-state combustion chamber temperature T in this manner, the fuel injection amount TAU of the engine 2 can be more accurately controlled.

(C). The actual combustion chamber temperature Tr is not directly measured from inside the combustion chamber 2c by the temperature sensor. The actual combustion chamber temperature Tr is determined by repeating the calculation of a new actual combustion chamber temperature Tr based on the temperature deviation ΔT between the already calculated actual combustion chamber temperature Tr and the steady-state combustion chamber temperature T. .

The steady-state combustion chamber temperature T obtained in step S185 represents a temperature at which the actual combustion chamber temperature Tr is finally stabilized with the passage of time. For this reason, especially, the actual combustion chamber temperature Tr during the transition is constantly changing toward the steady combustion chamber temperature T. The degree of this change is affected by the temperature deviation ΔT between the actual combustion chamber temperature Tr and the steady-state combustion chamber temperature T, the intake pressure PM, and the engine speed NE. Therefore, the behavior of the actual combustion chamber temperature Tr can be tracked from these ΔT, PM, and NE, and the actual combustion chamber temperature Tr can be continuously detected.

In this manner, even without attaching a temperature sensor or the like to the combustion chamber 2c, the actual combustion chamber temperature Tr can be easily detected with a simple configuration and used for estimating the intake air amount. This also enables accurate fuel injection amount control.

[Other Embodiments] Equation 1 for obtaining a new filling efficiency KTPt from the filling efficiency KTP obtained in step S120 of the first embodiment is an example, and for example, “ΔT / T” Instead of the term, another calculation term using ΔT, T may be used, and a calculation term using one or both of ΔT and T may be added to the term “ΔT / T”. .

In the first embodiment, the 2 shown in FIG.
In the dimension map, the steady-state combustion chamber temperature T is obtained from the intake pressure PM and the engine speed NE. In addition, other loads, for example, the throttle valve opening TA are used instead of the intake pressure PM. You may. That is, it may be configured as a two-dimensional map for obtaining the steady-state combustion chamber temperature T from the throttle valve opening TA and the engine speed NE.

In the first embodiment, the 2 shown in FIG.
The dimensional map is for obtaining the charging efficiency KTP from the intake pressure PM and the engine speed NE. In addition, instead of the intake pressure PM, for example, the throttle valve opening TA
May be used as a load. That is, it may be configured as a two-dimensional map for obtaining the charging efficiency KTP from the throttle valve opening TA and the engine speed NE.

[0099]

According to the first aspect of the present invention, the intake air amount estimating apparatus for an internal combustion engine further includes an intake air amount obtained based on an intake pressure, which is further associated with an actual combustion chamber temperature and an operating state of the internal combustion engine. Correction is made according to the temperature of the combustion chamber at a regular time. In this way, the actual combustion chamber temperature is further referred to together with the steady-state combustion chamber temperature, and based on the relationship between the two temperatures, the intake air amount is corrected to estimate the intake air amount of the internal combustion engine. For this reason, the temperature state of the residual gas in the combustion chamber can be reflected on the intake air amount calculated based on the intake pressure, and it is possible to accurately estimate the intake air amount even during a transition. Therefore, if the fuel supply amount is set using the data of the intake air amount, it is possible to sufficiently suppress the influence on the emission and the engine output during the transition.

In the intake air amount estimating device for an internal combustion engine according to the second aspect, the steady-state combustion chamber temperature calculating means detects the operating state of the internal combustion engine based on the operating state of the internal combustion engine detected by the internal combustion engine operating state detecting means. The temperature in the combustion chamber at the steady state in the state is obtained. Based on the steady-state temperature in the combustion chamber determined in this way, the actual combustion chamber temperature detected by the combustion chamber temperature detecting means, and the intake pressure detected by the intake pressure detecting means, The estimating means estimates an intake air amount of the internal combustion engine. Therefore, as in the case of the first aspect, the temperature state of the residual gas in the combustion chamber can be reflected on the intake air amount calculated based on the intake pressure, and the accurate intake air amount can be obtained even in the transient state. Can be estimated. Therefore, if the fuel supply amount is set using the data of the intake air amount, it is possible to sufficiently suppress the influence on the emission and the engine output during the transition.

According to a third aspect of the present invention, in the internal combustion engine intake air amount estimating apparatus, the internal combustion engine operating state detecting means determines the load and the rotation speed of the internal combustion engine based on the operation of the internal combustion engine. Detected as a state. Thus, the steady-state combustion chamber temperature calculating means can appropriately determine the steady-state combustion chamber temperature. Therefore, claim 2
In addition to the effects described above, the intake air amount of the internal combustion engine in the transient state can be more accurately estimated by the intake air amount estimating means by using the steady-state combustion chamber temperature obtained in this manner. Become like

According to a fourth aspect of the present invention, the load of the internal combustion engine is an intake pressure or a throttle valve opening. In this way, the intake pressure or the throttle valve opening can be used as the load.
The effect described in (1) occurs.

According to a fifth aspect of the present invention, there is provided a device for estimating an intake air amount of an internal combustion engine, wherein the temperature in the combustion chamber is not directly measured,
A new actual combustion chamber temperature is calculated based on the already calculated actual combustion chamber temperature and the steady combustion chamber temperature obtained by the steady combustion chamber temperature calculation means. The steady-state combustion chamber temperature obtained by the steady-state combustion chamber temperature calculation means is a direction in which the actual combustion chamber temperature changes, and represents a temperature that is finally stabilized with the passage of time. For this reason,
In particular, the actual combustion chamber temperature during the transition always changes toward the steady-state combustion chamber temperature corresponding to the operating state of the internal combustion engine at that time. The degree of this change is determined by the relationship between the actual combustion chamber temperature and the steady-state combustion chamber temperature. Therefore, the behavior of the actual combustion chamber temperature can be tracked from the relationship between the actual combustion chamber temperature and the steady-state combustion chamber temperature,
The actual combustion chamber temperature can be continuously detected. In this way, in addition to the effect of any one of claims 2 to 4, the temperature of the actual combustion chamber can be easily detected by a simple configuration without installing a temperature sensor or the like in the combustion chamber, and suction during transition is performed. It can be used to estimate the amount of air.

In the fuel supply control device for an internal combustion engine according to the sixth aspect, the fuel supply amount is controlled based on the intake pressure, the actual combustion chamber temperature, and the steady-state combustion chamber temperature. As described above, the actual combustion chamber temperature is referred to together with the steady-state combustion chamber temperature corresponding to the operating state of the internal combustion engine. For this reason, the temperature state of the residual gas in the combustion chamber is
This can be reflected in the calculation of the fuel supply amount, and it is possible to calculate a sufficiently accurate fuel supply amount corresponding to the actual intake air amount even during a transition. Therefore, it is possible to sufficiently suppress the influence on the emission and the engine output during the transition.

In the fuel supply control device for an internal combustion engine according to the seventh aspect, the steady-state combustion chamber temperature calculating means is configured to determine the operating state of the internal combustion engine based on the operating state detected by the internal combustion engine operating state detecting means. To obtain the temperature in the combustion chamber at the time of steady state. The fuel supply amount is determined based on the steady-state combustion chamber temperature obtained in this manner, the actual combustion chamber temperature detected by the combustion chamber temperature detection means, and the intake pressure detected by the intake pressure detection means. The control means controls a fuel supply amount to the internal combustion engine. Therefore, the fuel supply amount can be obtained by reflecting the temperature state of the residual gas in the combustion chamber as in the case of the above-described claim 6, and a sufficiently accurate amount corresponding to the actual intake air amount can be obtained even in the transient state. The fuel supply amount can be obtained. Therefore, it is possible to sufficiently suppress the influence on the emission and the engine output during the transition.

According to an eighth aspect of the present invention, in the fuel supply control device for an internal combustion engine according to the seventh aspect, the internal combustion engine operating state detecting means detects the load and the number of revolutions of the internal combustion engine by operating the internal combustion engine. Detected as Thus, the steady-state combustion chamber temperature calculating means can appropriately determine the steady-state combustion chamber temperature. For this reason, in addition to the effect of claim 7, the fuel supply amount to the internal combustion engine in the transient state can be made more accurate by the fuel supply amount control means by using the steady-state temperature in the combustion chamber thus obtained. Can be controlled.

According to a ninth aspect of the present invention, in the fuel supply control device for an internal combustion engine according to the eighth aspect, the load of the internal combustion engine is an intake pressure or a throttle valve opening. In this way, the intake pressure or the throttle valve opening can be used as the load, and the effect described in claim 8 is produced.

According to a tenth aspect of the present invention, in the fuel supply control device for an internal combustion engine according to any one of the seventh to ninth aspects, the combustion chamber temperature detecting means directly measures the temperature in the combustion chamber. Instead, a new actual combustion chamber temperature is calculated based on the already calculated actual combustion chamber temperature and the steady-state combustion chamber temperature obtained by the steady-state combustion chamber temperature calculation means. According to the mechanism described in the fifth aspect, the degree of the change in the actual combustion chamber temperature during the transition is affected by the relationship between the actual combustion chamber temperature and the steady-state combustion chamber temperature. Therefore, the behavior of the actual combustion chamber temperature can be tracked from the difference between the actual combustion chamber temperature and the steady-state combustion chamber temperature, and the actual combustion chamber temperature can be continuously detected. In this manner, in addition to the effect of any one of claims 7 to 9, the temperature of the actual combustion chamber can be easily detected with a simple configuration without attaching a temperature sensor or the like to the combustion chamber, and the temperature during transition can be easily detected. Accurate fuel supply control is possible.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a fuel injection amount control device for an internal combustion engine according to a first embodiment.

FIG. 2 is a flowchart of a fuel injection amount control process executed by an ECU according to the first embodiment;

FIG. 3 is a configuration explanatory diagram of a two-dimensional map used in Embodiment 1 for obtaining a charging efficiency KTP from an intake pressure PM and an engine speed NE.

FIG. 4 is a flowchart for obtaining a steady-state combustion chamber temperature T from the intake pressure PM and the engine speed NE used in the first embodiment;
FIG. 3 is an explanatory diagram of a configuration of a dimension map.

FIG. 5 is a flowchart of an actual combustion chamber temperature Tr estimating process executed by the ECU according to the first embodiment;

FIG. 6 is a graph showing a configuration of a temperature change response time constant map for obtaining a temperature change amount dt from the temperature difference ΔT, the intake pressure PM, and the engine speed NE used in the first embodiment.

FIG. 7 is a flowchart of an air-fuel ratio feedback coefficient FAF calculation process executed by the ECU according to the first embodiment;

FIG. 8 is a flowchart of an average value FAFAV calculation process of the air-fuel ratio feedback coefficient FAF executed by the ECU according to the first embodiment;

FIG. 9 is a flowchart of a process of learning an air-fuel ratio feedback coefficient FAF executed by the ECU according to the first embodiment;

FIG. 10 is a timing chart for explaining effects of the first embodiment.

[Explanation of symbols]

2 gasoline engine, 2a cylinder block, 2b
... Cooling water passage, 2c ... Combustion chamber, 4 ... Intake passage, 4a ... Surge tank, 6 ... Throttle valve, 6a ... Rotating shaft, 8 ...
Throttle valve opening sensor, 10 ... ECU (electronic control unit), 10a ... bus, 10b ... CPU, 10c ...
Memory, 10d input interface, 10e output interface, 12 intake pressure sensor, 12a intake pressure detection port, 12b pressure guiding tube, 14 intake port,
16: fuel injection valve, 17: fuel tank, 17a: fuel pump, 18: exhaust manifold, 20: air-fuel ratio sensor, 22: water temperature sensor, 24: pulse generator, 2
6. Reference position sensor.

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 3G084 BA13 DA11 DA12 FA10 FA11 FA18 FA19 FA22 FA33 3G301 HA01 JA04 JA21 KA11 LB01 LC01 MA13 MA14 NB02 PA07Z PA11Z PA17Z PC05Z PE01Z

Claims (10)

[Claims] An intake air amount estimating device for an internal combustion engine that calculates an intake air amount to an internal combustion engine based on an intake pressure, wherein the intake air amount calculated based on the intake pressure is determined by comparing an actual combustion chamber temperature with an actual combustion chamber temperature. An intake air amount estimating apparatus for an internal combustion engine, which estimates an intake air amount of the internal combustion engine by correcting the intake air amount of the internal combustion engine according to a steady-state temperature in a combustion chamber corresponding to an operation state of the internal combustion engine. 2. An intake pressure detecting means for detecting an intake pressure of the internal combustion engine, a combustion chamber temperature detecting means for detecting an actual combustion chamber temperature of the internal combustion engine, and an internal combustion engine operating state detecting means for detecting an operating state of the internal combustion engine. Based on the operating state of the internal combustion engine detected by the internal combustion engine operating state detecting means, steady-state combustion chamber temperature calculating means for obtaining a steady-state combustion chamber temperature in the operating state, the steady-state combustion chamber An internal combustion engine based on the steady-state combustion chamber temperature obtained by the temperature calculation means, the actual combustion chamber temperature detected by the combustion chamber temperature detection means, and the intake pressure detected by the intake pressure detection means. An intake air amount estimating device for an internal combustion engine, comprising: intake air amount estimating means for estimating the intake air amount of the internal combustion engine. 3. The intake air amount estimating apparatus for an internal combustion engine according to claim 2, wherein said internal combustion engine operating state detecting means detects a load and a rotation speed of the internal combustion engine as an operating state of the internal combustion engine. 4. The apparatus according to claim 3, wherein the load of the internal combustion engine is one of an intake pressure and a throttle valve opening. 5. The combustion chamber temperature detecting means, based on the already calculated actual combustion chamber temperature and the steady-state combustion chamber temperature obtained by the steady-state combustion chamber temperature calculating means, calculates a new actual combustion chamber temperature. The intake air amount estimating device for an internal combustion engine according to any one of claims 2 to 4, wherein: 6. A fuel supply control device for an internal combustion engine that calculates a fuel supply amount to the internal combustion engine based on an intake pressure, wherein a steady state corresponding to an intake pressure, an actual combustion chamber temperature, and an operation state of the internal combustion engine is provided. A fuel supply control device for an internal combustion engine, which controls a fuel supply amount to an internal combustion engine based on a temperature in a combustion chamber of the internal combustion engine. 7. An intake pressure detecting means for detecting an intake pressure of the internal combustion engine, a combustion chamber temperature detecting means for detecting an actual combustion chamber temperature of the internal combustion engine, and an internal combustion engine operating state detecting means for detecting an operating state of the internal combustion engine Based on the operating state of the internal combustion engine detected by the internal combustion engine operating state detecting means, steady-state combustion chamber temperature calculating means for obtaining a steady-state combustion chamber temperature in the operating state, the steady-state combustion chamber An internal combustion engine based on the steady-state combustion chamber temperature obtained by the temperature calculation means, the actual combustion chamber temperature detected by the combustion chamber temperature detection means, and the intake pressure detected by the intake pressure detection means. A fuel supply control device for an internal combustion engine, comprising: a fuel supply amount control unit that controls a fuel supply amount to a fuel supply device. 8. The fuel supply control device for an internal combustion engine according to claim 7, wherein said internal combustion engine operating state detecting means detects a load and a rotation speed of the internal combustion engine as an operating state of the internal combustion engine. 9. The fuel supply control device for an internal combustion engine according to claim 8, wherein the load of the internal combustion engine is one of an intake pressure and a throttle valve opening. 10. The combustion chamber temperature detecting means, based on the actual combustion chamber temperature already calculated and the steady-state combustion chamber temperature obtained by the steady-state combustion chamber temperature calculating means,
The fuel supply control device for an internal combustion engine according to any one of claims 7 to 9, wherein a new actual combustion chamber temperature is calculated.