JPH07166923A - Fuel supply controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To constantly maintain a fuel supply at a proper level even at the time of transient acceleration by estimating the fuel adhering to an intake system after intake stroke is finished by using the adhesion factor and the evaporation time constant of the fuel in the intake system, and by determining a fuel injection quantity based on the adhesion fuel and the required fuel quantity. CONSTITUTION:A required fuel quantity is calculated by a required fuel quantity calculation means M2 based on the driving condition of an internal combustion engine, while an adhesion fuel quantity for the fuel adhered to the intake system is calculated by an adhesion fuel quantity calculation means M3 by using the adhesion factor and the evaporation time constant of the fuel as a parameter indicating the behavior of the fuel in the intake system. A first adhesion fuel quantity for the fuel adhering to the intake system is estimated after an intake stroke is finished by using the adhesion factor and the evaporation time constant of the intake system. The difference between the estimated first adhesion fuel quantity and the calculated second adhesion fuel quantity one cycle prior to a current cycle, is added to the required fuel quantity by a fuel injection calculation means M4, so as to determine the fuel injection quantity of a fuel injection valve M1 in the current cycle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply amount for an internal combustion engine, which controls the amount of fuel injected and supplied to the internal combustion engine by using parameters (adhesion rate, evaporation rate) representing the behavior of the fuel in the internal combustion engine. Regarding the control device.

[0002]

2. Description of the Related Art Conventionally, a control device of this type, that is, a control device for controlling the amount of fuel supplied to an internal combustion engine based on the behavior of the fuel in the intake system is disclosed in, for example, Japanese Unexamined Patent Application Publication No. Hei 1 (1999) -163.
Device described in Japanese Patent Laid-Open No. 216042 or Japanese Patent Laid-Open No.
The device described in Japanese Patent No. 252833 is known.

Each of these control devices uses a fuel behavior model in which the behavior of the fuel flowing into the cylinder of the internal combustion engine is mathematically expressed with the amount of fuel adhering to the wall surface of the intake pipe of the internal combustion engine and its evaporation amount as parameters. Then, the fuel amount required for the internal combustion engine is obtained based on the operating condition of the internal combustion engine and the target value of the air-fuel ratio thereof, and the obtained required fuel amount is obtained according to the fuel behavior model in which the behavior of the fuel is mathematically expressed. From this, the amount of fuel to be actually supplied is calculated.

[0004]

As described above, in the above conventional control device, the fuel is injected and supplied to the internal combustion engine in accordance with the fuel behavior model using the parameter representing the behavior of the fuel flowing into the cylinder of the internal combustion engine. The amount of fuel that can be used becomes controlled. Therefore, if the parameters are properly set, will the controlled fuel supply amount be controlled to a proper supply amount that can bring the air-fuel ratio of the internal combustion engine close to the ideal air-fuel ratio? looks like.

However, in these conventional control devices, C.I.
F. Using the well-known Aquino formula as it is, calculate the amount of fuel adhering to the intake system of the internal combustion engine, and determine the amount of fuel to be injected into the engine based on the obtained fuel amount. I have to. For this reason, it was not possible to correctly recognize the amount of fuel actually entering the cylinder, especially during acceleration transition.

That is, in order to correctly recognize the amount of fuel actually entering the cylinder during acceleration transition or the like, it is necessary to observe the transition of the amount of fuel adhered in the intake system before and after fuel injection. However, the Aquino's formula is a formula for calculating the amount of fuel adhering to the intake system at that time based on the past amount of fuel adhering and the amount of fuel injection, and this formula is used as it is. As long as it is, it is impossible to accurately know the amount of fuel actually entering the cylinder during the acceleration.

Further, in the above-mentioned conventional control device, since the parameters showing the behavior of the fuel such as the fuel adhesion rate and the evaporation time constant in the intake system are given as a so-called two-dimensional map, many adaptations are required. It took man-hours and it was not easy to modify those maps.

The present invention has been made in view of such circumstances, and when controlling the amount of fuel to be injected and supplied to the internal combustion engine by using a parameter indicating the behavior of the fuel in the internal combustion engine, even during an acceleration transient or the like. It is an object of the present invention to provide a fuel supply amount control device for an internal combustion engine that can always maintain a proper fuel supply amount to the engine.

[0009]

In order to achieve such an object, according to the present invention, a fuel injection valve M1 for controlling the amount of fuel injection into an internal combustion engine, as shown in FIG.
The required fuel amount calculation means M2 for calculating the required fuel amount according to the operating conditions of the internal combustion engine, and the fuel adhesion rate and the evaporation time constant as parameters indicating the fuel behavior in the intake system of the internal combustion engine. Adhering fuel amount calculating means M3 for calculating the amount of fuel adhering to the system, and the adhering fuel amount adhering to the intake system after completion of the intake stroke of the internal combustion engine using the adhering rate of fuel and the evaporation time constant in the intake system. The first amount of adhered fuel is estimated, and the estimated first adhered fuel amount and the adhered fuel amount calculated by the adhering fuel amount calculating means are the amount of adhered fuel one cycle before the second amount. Fuel injection amount calculation means M4 for determining a fuel injection amount, which is the operation amount of the fuel injection valve in the relevant cycle, as a value obtained by adding the difference from the adhered fuel amount to the required fuel amount, is provided. .

[0010]

In the fuel injection amount calculating means M4, as described above, the first adhering fuel amount adhering to the intake system after the end of the intake stroke of the internal combustion engine using the adhering rate of fuel and the evaporation time constant in the intake system. Is trying to estimate. This is, for example, (a) the third amount of adhered fuel adhering to the intake system before fuel injection in the cycle and the amount of adhered fuel one cycle before for the third amount of adhered fuel. The provisional fuel injection amount in the relevant cycle is calculated as a value obtained by adding the difference from the adhered fuel amount of 1 to the required fuel amount. (B) The calculated provisional fuel injection amount and the third adhering fuel amount are substituted into the Aquino equation, and this is shifted by the number of calculations until the end of the intake stroke. It will be realized.

Further, in the fuel injection amount calculation means M4, the estimated first adhered fuel amount and the adhered amount of the first adhered fuel amount calculated by the adhered fuel amount calculation means M3 one cycle before are attached. The fuel injection amount, which is the operation amount of the fuel injection valve in the cycle, is obtained as a value obtained by adding the difference from the second adhered fuel amount, which is the fuel amount, to the required fuel amount. More specifically, for example, (c) As a value obtained by subtracting the difference between the estimated first deposited fuel amount and the second deposited fuel amount from the calculated provisional fuel injection amount, Further estimate the amount of fuel entering the cylinder. (D) The deviation between the estimated fuel amount entering the cylinder and the calculated required fuel amount is obtained. (E) The calculated deviation is added to the temporary fuel injection amount to update the temporary fuel injection amount. (F) When the deviation is within a predetermined value, the updated temporary fuel injection amount is determined as the desired fuel injection amount,
When the deviation does not reach the predetermined value, the above estimation, the deviation calculation, and the update of the temporary injection amount are re-executed based on the updated temporary fuel injection amount. It is realized in a more preferable form through such processing.

For this reason, even during acceleration transients,
Even when the amount of fuel adhering to the intake system increases at the end of the intake stroke after fuel injection, the amount of fuel actually entering the cylinder can be accurately recognized, and thus the amount of fuel supplied to the internal combustion engine is increased. The amount of fuel used will always be maintained properly.

As such a fuel supply amount control device, as shown in FIG. 9, the fuel evaporation time constant in the intake system is τ, the rotational speed of the internal combustion engine is Ne, and the intake pressure is the same. Is Pm,
Further, the reference rotational speed of the internal combustion engine is Neo, the intake pressure is also Pmo, the evaporation time constant of the fuel at the reference rotational speed Neo and the intake pressure Pmo is τo, and the reference intake pressure Pmo is The rate of change of the evaporation time constant τ with respect to the intake pressure Pm is f (P
m), the evaporation time constant τ of the fuel is

[0014]

[Equation 4]

Evaporation time constant calculating means M5
Further, the adhering fuel amount calculating means M3 and the fuel injection amount calculating means M4 calculate or estimate the adhering fuel amount,
The evaporation time constant τ calculated by the evaporation time constant calculating means M5 is used as the evaporation time constant of the fuel in the intake system. By doing so, at least for the evaporation time constant τ, it is not necessary to give this as a two-dimensional map as in the conventional control device. Therefore, the adaptation and modification thereof are extremely easy.

In addition to the above, the deposited fuel amount computing means M3 and the fuel injection amount computing means M4 calculate or estimate the deposited fuel amount,
When the adhesion rate of fuel in the intake system is x

[0017]

[Equation 5]

The same fuel adhesion rate x is used as If so, the above-mentioned adaptation becomes easier and more convenient. Further, by determining the attachment rate x and the evaporation time constant τ as in the equations (5) and (4), respectively, the responsiveness at the time of adaptation and parameter modification can be further improved. Therefore, the adhesion rate x
And, the determination of the evaporation time constant τ is significant in order to always maintain proper fuel supply accuracy as such a fuel supply amount control device.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic configuration of an internal combustion engine (engine) mounted on a vehicle and its electronic control unit as an embodiment of a fuel supply amount control device according to the present invention.

First, the construction of an engine to be controlled and its electronic control unit in this embodiment will be described with reference to FIG. For example, in an engine 1 assuming a 4-cylinder 4-cycle spark point type, its intake air passes from an air cleaner 2 through an intake pipe 3, a surge tank 4, an intake manifold, as shown in FIG. It is inhaled into each cylinder via 5.

On the other hand, fuel is pressure-fed from a fuel tank (not shown), and is injected and supplied from the fuel injection valve 6 provided in the intake manifold 5 toward each intake valve 15 of the engine 1.

The gas burned in the cylinder 1S of the engine 1 is introduced into the catalytic converter 8 through each exhaust valve 16 and the exhaust pipe 7, where the harmful component (C
O, HC, NOx) are cleaned by a three-way catalyst and discharged.

The air taken into the intake pipe 3 is
The flow rate is controlled by the throttle valve 9 which works in conjunction with the accelerator pedal. The opening of the throttle valve 9 is detected by the throttle opening sensor 10. The pipe pressure Pm of the intake pipe 3 is detected by the intake pressure sensor 11 provided in the surge tank 4.

The engine speed Ne of the engine 1 is
This is detected by a rotation speed sensor (crank angle sensor) 12 arranged near the crank shaft of the. The rotation speed sensor 12 is provided so as to face a ring gear that rotates in synchronization with the crankshaft of the engine 1. Here, for example, 24 pulse signals are output every two rotations (720 degrees) of the engine 1. It shall be.

The water temperature TW of the cooling water filled in the water jacket provided around the body of the engine 1
Is detected by the water temperature sensor 13. A thermistor is usually used as the water temperature sensor 13, and a change in the water temperature TW is detected as a change in the resistance value of the thermistor.

In the exhaust pipe 7, a catalytic converter 8 is also provided.
An air-fuel ratio sensor 14 that detects the actual unburned oxygen concentration of the exhaust gas in that portion and outputs this as an air-fuel ratio detection signal A / F is disposed in the upstream portion of the. Incidentally, in this case, the air-fuel ratio detection signal A / F output from the air-fuel ratio sensor 14 takes a linear value with respect to the actual air-fuel ratio of the air-fuel mixture supplied to the engine 1.

On the other hand, the electronic control unit 20 includes a well-known central processing unit (CPU) 21, read only memory (ROM) 22, random access memory (RAM) 23 and backup RAM 24.
It is configured as an arithmetic and logic operation circuit centered on etc. The arithmetic logic operation circuit is provided with a signal input from each sensor,
An input / output port (I / O port) 25 for outputting a control signal to each actuator is connected to each other via a bus. Then, in the electronic control unit 20, the throttle opening, the intake pipe internal pressure Pm, the rotation speed Ne, the cooling water temperature TW, the air-fuel ratio A /
Processing such as inputting sensor signals such as F and the like, calculating a fuel injection amount TAU based on these sensor signals, and controlling the drive of the fuel injection valve 6 based on the calculated fuel injection amount TAU Is executed via the same input / output port 24.

FIG. 2 shows a functional configuration of the electronic control unit 20 as a fuel supply amount control unit according to this embodiment.
Moreover, the configuration of the fuel supply amount control device and its function will be described in more detail below with reference to FIG.

Assuming that the fuel injection is completed before the intake stroke of the engine 1, the intake valve 15 is closed during the fuel injection period, and no fuel enters the cylinder 1S during that period. . Therefore, the injected fuel once adheres to the wall surface of the intake manifold 5.

In the apparatus of this embodiment, the parameters indicating the behavior of the fuel in the intake system of the engine 1 are: the adherence rate x of the fuel adhering to the wall surface of the intake manifold 5, and the adhering rate to the wall surface of the intake manifold 5. The amount of fuel to be injected and supplied to the engine 1 is controlled by using two parameters such as the ratio of the fuel sucked into the cylinder in the next control cycle, that is, the evaporation time constant τ among the above-mentioned fuel. However, for the above-mentioned fuel adhesion rate x,

[0031]

[Equation 6]

Therefore, the adaptation is simplified. In the electronic control unit 20 shown in FIG. 2, the required fuel amount calculation unit 201 detects the intake pressure Pm detected by the intake pressure sensor 11 as an operating condition of the engine 1 and the engine detected by the rotation speed sensor 12. This is a part for calculating the fuel amount required for the engine 1 based on the rotation speed Ne. This required fuel amount is GFET
Then,

[0033]

[Equation 7]

Can be calculated as The obtained required fuel amount GFET is given to the fuel injection amount calculation unit 207. The required fuel amount calculation unit 201 can be realized as a lookup table using the ROM 22.

In the electronic control unit 20, the evaporation time constant calculating unit 202 also calculates the intake pressure Pm similarly detected by the intake pressure sensor 11 and the engine speed Ne detected by the rotation speed sensor 12, This is a part for calculating the evaporation time constant τ which is another parameter expressing the behavior of the fuel.

This evaporation time constant τ is as shown in FIG.
Time constant τ due to evaporation from the injection of fuel to the end of the intake stroke
1 and the time constant τ2 due to the droplet are comprehensively evaluated. That is, the evaporation time constant τ is

[0037]

[Equation 8]

Is represented by FIG. 3 shows the behavior of the amount of fuel adhering to the wall surface of the intake manifold 5. Hereinafter, referring to FIG. 3 and FIGS. A method of calculating the constant τ will be described.

First, in the area A shown in FIG. 3, the intake valve 15
Is closed, part of the fuel adhering to the wall surface of the intake manifold 5 evaporates and the intake manifold 5 is closed.
Remains inside (all of this evaporated fuel is sucked into the cylinder 1S by opening the intake valve 15). Therefore, the evaporation time constant τ1 in the region A is determined only by the intake pressure Pm.

By the way, looking at the relationship between two different values of the intake pressure Pm and the evaporation time constant τ1, as shown in FIG.

[0041]

[Equation 9]

It is known that there is such a relationship.
Therefore,

[0043]

[Equation 10]

As described above, it can be seen that the evaporation time constant τ1 in the region A is determined only by the intake pressure Pm. On the other hand, in the intake stroke shown as the region B in FIG. 3, the adhered fuel is sucked into the cylinder 1S along the gas flow as droplets. Therefore, the inhaled amount depends on the gas flow velocity,

[0045]

[Equation 11]

The time constant τ2 that enters the cylinder 1S as it is is as follows.

[0047]

[Equation 12]

Will be determined as As shown in FIG. 5, the relationship between the time constant τ2 due to the liquid droplets and the rotational speed Ne and the intake pressure Pm is as follows if the intake pressure Pm is constant.

[0049]

[Equation 13]

If the rotation speed Ne is constant,

[0051]

[Equation 14]

It becomes As described above, equation (8) and (10)
When the relationship between the time constants τ1 and τ2 is summarized by the relationship between the expression and the expression (12), the following result is obtained as the value of the time constant τ. (I) Time constant τ when the intake pressure Pm is constant

[0053]

[Equation 15]

Therefore,

[0055]

[Equation 16]

(Ii) Time constant τ when the rotation speed Ne is constant

[0057]

[Equation 17]

As described above, the tendency of the time constants τ1 and τ2 is opposite to that of the intake pressure Pm, and the tendency of the time constant τ is determined by the dependence of the time constants τ1 and τ2. Therefore,

[0059]

[Equation 18]

In an engine having a large dependence on the time constant τ1,

[0061]

[Formula 19]

On the contrary, in the case of an engine having a large dependence of the time constant τ2,

[0063]

[Equation 20]

It becomes To summarize the results of these (i) and (ii), from the above equations (16) and (18),

[0065]

[Equation 21]

Will be obtained. However, this (2
In the equation (1), Neo is the reference number of revolutions of the engine 1, and τo is the evaporation time constant at the reference number of revolutions Neo and the reference intake pressure Pmo, and f (Pm)
Indicates the rate of change of the evaporation time constant τ with respect to the intake pressure Pm based on the evaporation time constant τ at the reference intake pressure Pmo.

The evaporation time constant calculation unit 202 executes the calculation of the equation (21) based on the intake pressure Pm detected by the intake pressure sensor 11 and the engine speed Ne detected by the rotation speed sensor 12. Thus, the evaporation time constant τ, which is a parameter representing the fuel behavior, is calculated.

For example, the reference rotational speed Neo is 1
000 rpm, the reference intake pressure Pmo is 290 mmHg, and the evaporation time constant τo at that time
Is 65.3 ms, and on the other hand, if the rate of change f (Pm) of the evaporation time constant τ with respect to the intake pressure Pm is set as in the table illustrated in FIG. (1) The table of FIG. 6 is searched by the intake pressure Pm detected by the intake pressure sensor 11, and the corresponding change rate f (Pm) of the evaporation time constant τ is obtained. (2) The ratio (Neo / Ne) between the reference rotation speed Neo and the rotation speed Ne detected by the rotation speed sensor 12 is obtained. (3) The rate of change f (P
m), the rotation speed ratio (Neo / Ne), and the evaporation time constant τo under the above-mentioned standard operating conditions. In this manner, the evaporation time constant τ will be obtained. The calculated evaporation time constant τ is the adhesion rate x (=
Along with 1), it is given to the adhered fuel amount calculation unit 203 and the fuel injection amount calculation unit 207, respectively. The table illustrated in FIG. 6 is also realized as, for example, a look-up table using the ROM 22, and values not included in this table are appropriately interpolated.

Further, in the electronic control unit 20 (FIG. 2), the adhered fuel amount calculation unit 203 has an adherence rate x (= 1), which is a parameter representing the fuel behavior, and the evaporation time constant τ obtained above, and will be described later. Based on the fuel injection amount GF,
This is a part for calculating the amount of fuel adhering to the intake manifold 5.

The amount of fuel adhering to the intake manifold 5 is C.I. F. According to the Aquino formula

[0071]

[Equation 22]

Is given as In the equation (22), Δt represents the sampling period (calculation period) of the apparatus of the embodiment, Gf (t) is the fuel injection amount per unit time, and GF is the injection fuel amount in one stroke. Shown respectively.

In the adhered fuel amount calculation unit 203, this (2
The fuel amount MF adhering to the intake manifold 5 is calculated based on the equation (2). However, the same (22)
In the formula, MF (t-Δt) means the amount of adhered fuel MF calculated one time before that. Therefore, in this electronic control unit 20, the attached fuel amount MF calculated by the attached fuel amount calculation unit 203 is temporarily stored in the auxiliary storage unit 204, and at the time of the next calculation, the stored attached fuel amount MF is stored.
Is referred to as the “adhesion fuel amount MF (t−Δt) before one time” and is read out to the adhesion fuel amount calculation unit 203.

The adhered fuel amount MF thus obtained
Is given to the writing control / adhesion change amount calculation unit 205. Write control / adhesion change amount calculation unit 205
Is, for example, a crank angle sensor of the engine 1 (not shown)
It is a part for controlling the writing of the calculated adhered fuel amount MF to the storage unit 206 based on the stroke management information which is supposed to be formed based on the detection output from FIG.

Here, the stroke management information refers to the distinction of strokes such as "compression stroke", "ignition stroke", "exhaust stroke", and "intake stroke" as shown in FIG. 3 when the engine 1 is operated. This is information indicating the fuel injection timing and the like in real time.

Write control / adhesion change amount calculation unit 205
Then, based on such stroke management information, (1) immediately after the end of the intake stroke, the calculated adhered fuel amount MF is written in the storage unit 206 as MF72. (2) Immediately before the fuel injection, the calculated adhered fuel amount MF is written in the storage unit 206 as MF48. Write control is executed. In addition, these MF7
2 or MF48 means the amount of adhering wall surface of the intake manifold 5 at the portions (time points) indicated by the same names in FIG.

In addition, in the writing control / adhesion change amount calculation unit 205, when the stroke management information indicates that it is just before the fuel injection in (2) above, (3) one cycle before the time point Adhesive fuel amount M
F48 is read from the storage unit 206, and a value obtained by subtracting the adhered fuel amount MF48 of one cycle before from the calculated adhered fuel amount MF (the adhered fuel amount written as MF48 this time) is calculated. (4) Then, regarding the obtained value, that is, the variation amount of the adhered fuel amount MF48 immediately before the fuel injection in one cycle, this is separately written in the storage unit 206 as ΔMF48. Such processing is also executed.

Write control / adhesion change amount calculation unit 205
Through the above write control and the calculation of the amount of change in adhesion, the storage unit 206 stores the amounts of adhered fuel MF72 and MF48, and the amount of change ΔMF48 related to the amount of adhered fuel MF48 each time. Then, the adhering fuel amounts MF72, MF48 and the adhering fuel amount change amount ΔMF48 are read by the fuel injection amount calculation unit 207 and used for the calculation of the fuel injection amount through the calculation unit 207. As the storage unit 206, normally,
The RAM 23 or the backup RAM 24 is used.

The fuel injection amount calculation unit 207 calculates the required fuel amount GFET calculated above, the fuel adhesion rate x (= 1), the fuel evaporation time constant τ, and the adhered fuel amount MF72 stored in the storage unit 206. This is a part for calculating the fuel injection amount, which is the operation amount of the fuel injection valve 6, based on the MF48 and the attached fuel amount change amount ΔMF48.

This fuel injection amount calculation unit 207 basically uses (1) the fuel adhesion rate x (= 1) in the intake manifold 5 and the evaporation time constant τ to determine the engine 1
After the end of the intake stroke, the attached fuel amount MF72 '(see FIG. 3) attached to the intake manifold 5 is estimated. (2) The estimated attached fuel amount MF72 ′ and the storage unit 2
The fuel injection amount Gf in the relevant cycle is obtained as a value obtained by adding the difference from the attached fuel amount MF72 read from 06 to the required fuel amount GFET. The calculation of the fuel injection amount Gf is executed in this manner.

A specific calculation mode in the fuel injection amount calculation unit 207 will be described below. First, the fuel amount supplied to the cylinder 1S of the engine 1 during one stroke is a value obtained by subtracting the fuel amount adhering to the intake manifold 5 from the fuel injection amount during the same stroke.

The amount of fuel adhered during this one stroke is
The estimated fuel amount MF72 ′ after the end of the intake stroke estimated above
And the attached fuel amount MF read from the storage unit 206, which is the attached fuel amount one cycle before (720 ° CA).
The difference from 72 can be expressed as:

Therefore, when the amount of fuel actually supplied to the cylinder 1S during one stroke is GFe,

[0084]

[Equation 23]

Will be given as This (2
In Expression 3), Gf is the fuel injection amount calculated by the fuel injection amount calculation unit 207. On the other hand, the fuel amount GFe actually supplied to the cylinder 1S and the required fuel amount G calculated by the previously required fuel amount calculation unit 201.
Assuming that the fuel injection amount Gf is set so as to be equal to the FET, the fuel injection amount Gf is

[0086]

[Equation 24]

It will be obtained as That is, here, the estimated fuel adhesion amount MF7 after the end of the intake stroke is estimated.
Only 2'is an unknown value, and this adhered fuel amount MF72 '
If the value of can be estimated, the fuel injection amount Gf in the relevant cycle can be obtained based on the equation (24).

Then, a method of estimating the amount of adhered fuel MF72 'after the end of the intake stroke will be described. Now, as the temporary fuel injection amount GF ′, the fuel amount obtained by adding the change amount ΔMF48 of the attached fuel amount MF48 immediately before the fuel injection read from the storage unit 206 to the required fuel amount GFET is obtained. That is,

[0089]

[Equation 25]

Here, the calculated temporary fuel injection amount GF '
Substituting into the above equation (22) and rearranging, the unknown adhered fuel amount MF72 ′ after the end of the intake stroke is

[0091]

[Equation 26]

Can be estimated as
In the equation (26), the MF 48 determines that the adhered fuel amount calculation unit 2 immediately before the fuel injection in the cycle.
03 is the amount of the adhered fuel calculated in 03 and registered in the storage unit 206, and n is the calculated amount of the adhered fuel MF4.
8 is the number of calculations required from the registration (memorization) to the end of the intake stroke.

Further, if the adhered fuel amount MF72 'after the intake stroke can be estimated in this way, this can be substituted into the above equation (23) to also calculate the tentative fuel amount GFe' actually entering the cylinder 1S. ,

[0094]

[Equation 27]

Can be estimated as
Therefore, in the fuel injection amount calculation unit 207, the deviation D between the required fuel amount GFET and the estimated fuel amount (fuel amount entering the cylinder 1S) GFe ′ is calculated.

[0096]

[Equation 28]

First of all, Then, regarding the tentative fuel injection amount GF ′ calculated above, this is also calculated using the obtained deviation D.

[0098]

[Equation 29]

Updating as, the above equations (26) to (2
When the calculation of the equation (9) is repeated and the deviation D becomes almost "0",

[0100]

[Equation 30]

As a result, the updated (estimated) temporary fuel injection amount GF 'is determined as the fuel injection amount Gf in the cycle. The fuel injection amount Gf thus determined is given to the injection management unit 208, and through the management unit 208 referring to the stroke management information, (1) if the fuel injection timing, the operation amount T of the fuel injection valve 6
It is converted into units of AU and applied to the fuel injection valve 6. That is, fuel injection is executed. (2) Immediately after the end of fuel injection (when the wall surface adhesion amount shown in FIG. 3 reaches a peak), the fuel injection amount Gf is the injected fuel amount GF in one stroke, and the adhered fuel amount calculation unit 20.
Given to 3. (3) If it is neither the fuel injection timing nor immediately after the end of the fuel injection, the value “0” is given to the adhered fuel amount calculation unit 203 as the injected fuel amount GF in the same stroke. Will be processed.

FIG. 7 and FIG. 8 show a series of processing procedures for the processing actually performed by the electronic control unit 20 to control the fuel supply amount to the engine 1. 8 and FIG. 8 together, the operation of the control device of this embodiment will be described in more detail.

In the control device of this embodiment, the electronic control device 20 executes the following processing at every sampling time Δt (for example, 60 ° CA). That is, the electronic control unit 20 firstly, via the input / output port 25, the engine speed Ne which is the detection output of the rotation speed sensor 12, and the intake pipe internal pressure (intake pressure) Pm which is the detection output of the intake pressure sensor 11. Is taken in (step S100).

Next, the electronic control unit 20 sets the required fuel amount GFET through the required fuel amount calculation unit 201 and the evaporation time constant τ through the evaporation time constant calculation unit 202 to the engine speed Ne and the intake pressure Pm which have been taken in, respectively. The calculation is performed accordingly (step S101). The required fuel amount G
As described above, the calculation of the FET is executed based on the above expression (7), and the calculation of the evaporation time constant τ is executed based on the above expression (21).

In this way, the electronic control unit 20 which obtains the required fuel amount GFET and the evaporation time constant τ under the operating condition
Determines whether or not the current time is just before fuel injection based on the stroke management information (step S102). As a result, when it is determined that it is just before the fuel injection, the calculation of the fuel amount MF adhering to the intake manifold 5 at that time, that is, the adhering fuel amount MF48 is executed through the adhering fuel amount calculating unit 203. Yes (Step S
103). It is also described above that this calculation is executed based on the above equation (22). However, at this point in time, fuel has not yet been injected, so the value "0" is used as the injected fuel amount GF.

The electronic control unit 20 which has calculated the adhered fuel amount MF48 in this way then subtracts the value of the adhered fuel amount MF48 one cycle before from the adhered fuel amount MF48 through the write control and adhered change amount calculator 205. A value, that is, the amount of change ΔMF48 is calculated (step S104). Then, the obtained change amount ΔMF48 is stored (registered) in the storage unit 206 together with the calculated adhered fuel amount MF48 (step S105).

Next, the electronic control unit 20 includes the storage unit 206.
Together with the value already registered for the adhered fuel amount MF72, the newly registered adhered fuel amount MF48
And its change amount ΔMF48 are read (step S10).
6), these read values and the required fuel amount GF obtained above
The ET and the evaporation time constant τ are given to the fuel injection amount calculation unit 207 to start the calculation of the fuel injection amount Gf.

That is, the fuel injection amount calculation unit 2
At 07, the calculation of the fuel injection amount Gf is executed by the procedure listed below. (1) The required fuel amount GFET and the adhered fuel amount change amount Δ
Substituting MF48 into equation (25), the temporary fuel injection amount GF '
Is calculated (step S107). (2) The tentative fuel injection amount GF ′ obtained above is substituted into the equation (26) together with the attached fuel amount MF48 and the evaporation time constant τ to estimate the attached fuel amount MF72 ′ at the end of the intake stroke in the cycle. (Step S108). (3) The estimated amount of adhered fuel MF72 ′ together with the amount of adhered fuel MF72 and the temporary fuel injection amount GF ′ (27)
Substituting into the formula, the actual fuel amount GF entering the cylinder 1S GF
E'is estimated (step S109). (4) The estimated fuel amount GFe ′ is set to the required fuel amount G
By substituting it into the equation (28) together with the FET, the deviation D between these required fuel amount GFET and the estimated fuel amount GFe ′ entering the cylinder 1S is obtained (step S110). (5) The calculated deviation D is substituted into the equation (29) together with the temporary fuel injection amount GF 'calculated in the process of (1), and the temporary temporary fuel injection amount GF' is updated (step S11
1). (6) The absolute value of the deviation D obtained in the process of (4) above is compared with a predetermined value k close to "0" (step S11).
2). (7) As a result of this comparison, when the absolute value of the deviation D is larger than the predetermined value k, the processes of (2) to (5) are repeatedly executed (steps S108 to S1).
11). (8) If the absolute value of the deviation D is less than the predetermined value k as a result of the comparison, including the repetition of the processes of (2) to (5), the amount of adhered fuel at the end of the intake stroke is M
It is determined that the estimation of F72 ′ has been properly performed, and the provisional fuel injection amount GF ′ updated (estimated) at that time is determined as the fuel injection amount Gf to be obtained (step S113).

When the fuel injection amount Gf is thus obtained through the fuel injection amount calculation unit 207, the electronic control unit 20 next determines through the injection management unit 208 whether or not the current time is the fuel injection start time (step S114). ).

As a result, when it is judged that it is the fuel injection start timing, the fuel injection amount Gf obtained above is multiplied by a predetermined unit conversion coefficient through the injection management unit 208,
The manipulated variable TAU of the fuel injection valve 6 is applied to the fuel injection valve 6 via the input / output port 25. That is, fuel injection is executed (step S115).

On the other hand, when it is determined that the current time is not the fuel injection start timing, the injection management unit 208 further determines whether or not the current time is immediately after the end of fuel injection (step S116). In the determination as to whether or not it is immediately before the fuel injection (step S102),
When it is determined that the time is not immediately before the fuel injection, the process directly moves to the determination of whether or not it is immediately after the end of the fuel injection (step S116).

As a result, when it is determined that the fuel injection has just been completed, the fuel injection amount Gf is given to the adhered fuel amount calculation unit 203 as the injected fuel amount GF in one stroke (step S117). When it is determined that it is not immediately after the end of fuel injection, that is, when the determination of step S102 is directly transferred to the determination of step S116,
As the injected fuel amount GF during the same stroke, a value “0” is given to the same attached fuel amount calculation unit 203 (step S11).
8).

As a result, in the attached fuel amount calculation unit 203,
The given injection fuel amount GF is substituted into the equation (22) together with the previously calculated evaporation time constant τ and the attached fuel amount MF (t−Δt) previously calculated by the attached fuel amount calculation unit 203. , The intake manifold 5 at that time
The fuel amount MF adhering to the vehicle is calculated (step S119).

In this way, the electronic control unit 20 which has obtained the adhering fuel amount MF at that time further determines whether or not the present time is immediately after the end of the intake stroke based on the stroke management information (step S120), and the intake stroke When it is determined that the writing is just finished, the writing control and adhesion change amount calculation unit 205
Through the obtained adhered fuel amount MF.
It is stored in the storage unit 206 as 2 (registration update) (step S121). If it is determined in step S120 that the current time is not immediately after the end of the intake stroke, the Δt routine ends.

As described above, in the fuel supply amount control device of this embodiment, the fuel amount MF72 'adhering to the intake manifold 5 is estimated immediately after the intake stroke is finished, and the fuel amount to be injected and supplied to the engine 1 is estimated. Gf is determined.

Therefore, during acceleration transition or the like, even if the amount of adhered wall surface to the intake manifold 5 may increase after fuel injection, for example, as indicated by a broken line in FIG. 3, the cylinder 1S is actually used. It will be possible to accurately recognize this regarding the amount of fuel entering. Therefore, the amount of fuel supplied to the engine 1 can always be maintained properly.

Further, in the control apparatus of the embodiment, the adhesion rate x and the evaporation time constant τ are adopted as the parameters showing the behavior of the fuel on the wall surface of the intake manifold 5, and each of these parameters is expressed by equation (6). And equation (21).

For this reason, the adaptation and the parameter modification become extremely easy, and the responsiveness in the adaptation and the parameter modification is further improved. In addition, in the control device of the embodiment, the evaporation time constant τ, especially the intake pressure Pm
In order to obtain the change rate f (Pm) of the evaporation time constant τ with respect to
Alternatively, it can be given in the form of a function such as

That is, the cylinder 1S is formed by the evaporation.
In the case of an engine in which the time constant τ1 of the amount of fuel entering is dominant,

[0120]

[Equation 31]

As, the evaporation time constant τ with respect to the intake pressure Pm
In the case of an engine in which the time constant τ2 of the amount of fuel entering the cylinder 1S as the droplets is dominant,

[0122]

[Equation 32]

As a change rate f (Pm) of the evaporation time constant τ with respect to the intake pressure Pm can be given. here,
The above l or l'is an arbitrary constant. Further, in the control device of the above embodiment, as shown in the flowchart of FIG. 7, the estimated value GFe ′ of the fuel amount actually entering the cylinder 1S is the required fuel amount GFET obtained from the rotation speed Ne and the intake pressure Pm. Until the values are almost the same, step S10
Although the processing from 8 to step S112 is repeated, for example: -When the processing from step S108 to step S112 is repeated an arbitrary number of times, the fuel injection amount Gf determination processing (step S113) is executed. It is also possible to change to such a routine. Even if the number of times of repetition is, for example, about two times, the above estimation can be achieved with sufficient accuracy in practical use, and if the number of times of repetition is suppressed to about two times, the response as the control device is obtained. The property will be further improved.

Furthermore, if the following algorithm is adopted for the estimation of the adhered fuel amount MF72 'at the end of the intake stroke and the calculation of the fuel injection amount Gf, the processes of steps S108 to S112 can be repeated. The fuel injection amount Gf (GF) can be directly determined without depending on it.

That is, the adhered fuel amount M at the end of the intake stroke
F72 ′ is given by the following equation based on the above equation (26).

[0126]

[Expression 33]

Further, the fuel injection amount GF to be obtained here
Is from the above equation (24),

[0128]

[Equation 34]

Is given as Therefore, this (3
By substituting the equation (33) into the estimated adhered fuel amount MF72 ′ of the equation 4),

[0130]

[Equation 35]

As a result, the fuel injection amount GF can be directly obtained from all known values. In this case, the fuel injection amount calculation unit 207 may be configured as a unit that executes the calculation of the equation (35).

Further, in the control apparatus of the embodiment, a routine for calculating the fuel injection amount and a routine for calculating the fuel amount adhering to the intake system and updating the registered value (memorized value) are
Although they are treated as one continuous Δt routine, it is of course possible to treat each of these routines as, for example, each different routine executed in parallel or at another time zone.

Further, in the above embodiment, the device (6) for determining the fuel amount Gf to be injected and supplied to the engine 1 by estimating the intake system adhered fuel amount MF72 'at the end of the intake stroke is provided.
The case where the adhesion rate x and the evaporation time constant τ set as in the equations and (21) are applied is described.
Also, the application mode of the evaporation time constant τ is arbitrary.

That is, even when the attachment rate x and the evaporation time constant τ are given as, for example, a two-dimensional map as in the conventional control device, the intake system attached fuel amount MF72 ′ at the end of the intake stroke is estimated to estimate the engine. According to the above configuration that determines the amount of fuel to be injected and supplied to the fuel cell, it is possible to always maintain the amount of fuel to be supplied appropriately.

Although the mode of the above embodiment is more desirable, if at least the evaporation time constant τ is set as in the above (21), the suitability as the control device is greatly improved. Like

Further, for a device that controls the fuel supply amount by using the adhesion rate x and the evaporation time constant τ as parameters representing the fuel behavior in the intake system of the engine, these values are expressed by the above equations (6) and (21). Even if it is set only by the equation (4), it is possible to obtain a significant effect in facilitating the adaptation and the parameter modification, and by keeping the fuel supply accuracy always proper.

[0137]

As described above, according to the present invention, the amount of fuel adhered to the intake system of the internal combustion engine increases at the end of the intake stroke after fuel injection even during acceleration transition or the like. Even if there is, it becomes possible to accurately recognize the amount of fuel actually entering the cylinder. Therefore, the amount of fuel supplied to the internal combustion engine can always be maintained appropriately.

The fuel adhesion rate is x, the evaporation time constant is τ, the internal combustion engine rotational speed is Ne at each time, the intake pressure is Pm, and the internal combustion engine reference rotational speed is Ne.
o, the intake pressure is also Pmo, and the evaporation time constant of the fuel at the engine speed Neo and the intake pressure Pmo is τ.
o, and the rate of change of the evaporation time constant τ with respect to the intake pressure Pm based on the evaporation time constant τ at the reference intake pressure Pmo is f (Pm),

[0139]

[Equation 36]

By determining the fuel attachment rate x and the evaporation time constant τ as described above, the response in conformity and parameter modification can be further improved, and the fuel supply accuracy can be properly maintained.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a fuel supply amount control device for an internal combustion engine according to the present invention.

FIG. 2 is a block diagram showing a functional and specific configuration example of the electronic control device of the control device of the embodiment.

FIG. 3 is a graph showing the behavior of the amount of fuel adhering to the wall surface of the intake manifold.

FIG. 4 is a graph showing a relationship between an intake pressure and a fuel evaporation time constant in a region A of the graph of FIG.

5 is a graph showing the relationship between the rotational speed and intake pressure in the region B of the graph of FIG. 3, and the time constant due to fuel droplets.

FIG. 6 shows a change rate f (Pm) of the evaporation time constant with respect to the intake pressure, among the evaporation time constants determined by the control device of the embodiment.
5 is a schematic diagram showing an example of a conversion table for the components of FIG.

FIG. 7 is a flowchart mainly showing a procedure for calculating a fuel injection amount by the control device of the embodiment.

FIG. 8 is a flowchart mainly showing a processing procedure for calculating and storing a deposited fuel amount by the control device of the embodiment.

FIG. 9 is a claim correspondence diagram.

[Explanation of symbols]

1 ... Engine, 1S ... Cylinder, 2 ... Air cleaner, 3
... intake pipe, 4 ... surge tank, 5 ... intake manifold, 6 ... fuel injection valve, 7 ... exhaust pipe, 8 ... catalytic converter, 9 ... throttle valve, 10 ... throttle opening sensor, 11 ... intake pressure sensor, 12 ... Rotation speed sensor, 13 ...
Water temperature sensor, 14 ... Air-fuel ratio sensor, 15 ... Intake valve, 16
... Exhaust valve, 20 ... Electronic control unit, 21 ... CPU, 22 ...
ROM, 23 ... RAM, 24 ... Backup RAM, 2
5 ... I / O port, 201 ... Required fuel amount calculation unit, 202
... Evaporation time constant calculation unit, 203 ... Adhering fuel amount calculation unit, 20
4 ... Auxiliary storage unit, 205 ... Writing control and adhesion change amount calculation unit, 206 ... Storage unit, 207 ... Fuel injection amount calculation unit,
208 ... Injection management unit.

Claims (5)

[Claims] 1. A fuel injection valve for operating a fuel injection amount to an internal combustion engine, a required fuel amount calculation means for calculating a required fuel amount according to an operating condition of the internal combustion engine, and a fuel behavior in an intake system of the internal combustion engine. Using the fuel adhesion rate and the evaporation time constant as the parameters, the adhered fuel amount calculation means for calculating the amount of fuel adhering to the intake system and the fuel adhesion rate and the evaporation time constant in the intake system are used. After the completion of the intake stroke of the internal combustion engine, the first adhered fuel amount adhering to the intake system is estimated, and the estimated first adhered fuel amount and the first adhered fuel amount calculated by the adhered fuel amount calculating means are calculated. The fuel injection amount, which is the operation amount of the fuel injection valve in the cycle, is defined as a value obtained by adding the difference between the fuel amount and the second adhered fuel amount, which is the adhered fuel amount one cycle before, to the required fuel amount. Required fuel injection amount calculation Fuel supply amount control apparatus for an internal combustion engine, characterized in that it comprises a stage, a. 2. A fuel supply amount control apparatus for an internal combustion engine according to claim 1, wherein the evaporation time constant of the fuel in the intake system is τ, the rotational speed of the internal combustion engine at each time is Ne, and the intake pressure is Pm, Further, the reference rotational speed of the internal combustion engine is Neo, the intake pressure is also Pmo, the evaporation time constant of the fuel at the reference rotational speed Neo and the intake pressure Pmo is τo, and the reference intake pressure Pmo is F (Pm) is the rate of change of the evaporation time constant τ with respect to the intake pressure Pm based on the evaporation time constant τ of
And the evaporation time constant τ of the fuel is And a fuel injection amount calculation means for calculating or estimating the amount of adhered fuel, which is used as an evaporation time constant of the fuel in the intake system. A fuel supply amount control device for an internal combustion engine, which uses an evaporation time constant τ calculated by a time constant calculation means. 3. The fuel supply amount control device for an internal combustion engine according to claim 2, further comprising: the adhering fuel amount calculating means and the fuel injection amount calculating means in the intake system when calculating or estimating the adhered fuel amount. When the fuel adhesion rate is x A fuel supply amount control device for an internal combustion engine, wherein the same fuel adhesion rate x is used as 4. The fuel injection amount calculation means includes a third amount of adhered fuel adhering to the intake system before fuel injection in the cycle and a value of 1 for the third amount of adhered fuel.
Temporary injection amount calculation means for calculating the temporary fuel injection amount in the cycle as a value obtained by adding the difference from the fourth adhered fuel amount, which is the amount of adhered fuel before the cycle, to the required fuel amount, and the calculated amount. First estimating means for estimating the first attached fuel amount based on the tentative fuel injection amount and the third attached fuel amount, and the estimated first attached fuel amount and the second attached fuel amount. Second estimating means for further estimating the fuel amount entering the cylinder of the internal combustion engine as a value obtained by subtracting the difference from the fuel amount from the calculated temporary fuel injection amount, and the estimated fuel amount entering the cylinder and the Deviation calculating means for calculating a deviation from the calculated required fuel quantity; temporary injection quantity updating means for updating the temporary fuel injection quantity by adding the calculated deviation to the temporary fuel injection quantity; When the value of The amount is determined as the required fuel injection amount, and when the deviation does not fall within a predetermined value, the updated temporary fuel injection amount is given to the first and second estimating means to re-execute the estimation. The fuel supply for the internal combustion engine according to claim 1, 2 or 3, further comprising: control means for re-executing the deviation calculation by the deviation calculation means and the update of the temporary injection quantity by the temporary injection quantity update means. Quantity control device. 5. A fuel adhesion rate and an evaporation time constant are used as parameters representing the fuel behavior in an intake system of an internal combustion engine,
A fuel for an internal combustion engine that determines the amount of fuel to be supplied to the internal combustion engine at each time based on the required fuel amount determined according to the operating condition of the internal combustion engine and the deposition rate and evaporation time constant of these fuels corresponding to the operating condition In the supply amount control device, x is the adhesion rate of the fuel, τ is the evaporation time constant, Ne is the number of revolutions of the internal combustion engine at each time, and Pm is the intake pressure.
Further, the reference rotational speed of the internal combustion engine is Neo, the intake pressure is also Pmo, the evaporation time constant of the fuel at the reference rotational speed Neo and the intake pressure Pmo is τo, and the reference intake pressure Pmo is The rate of change of the evaporation time constant τ with respect to the intake pressure Pm is f (P
m), we have A fuel supply amount control device for an internal combustion engine, wherein the fuel adhesion rate x and the evaporation time constant τ are determined as the above.