JP2002349318A - Fuel injection control apparatus for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow an injection amount through injection valves disposed on an upstream side and a downstream side of a throttle valve to be determined in consideration of a portion of fuel that adheres to an inner wall of an intake pipe at the upstream side and is thereafter released therefrom and flows into a downstream fuel. SOLUTION: A fuel amount TinTH is calculated by totaling an amount of fuel that flows from an upstream injection valve 10 into a downstream fuel of a throttle valve 9, an amount of fuel that, of the total amount of fuel injected from the upstream injection valve 10, adheres to the inner wall on the upstream side of the valve 9 and is thereafter released therefrom to flow into the downstream fuel of the valve 9, and an amount of fuel injected from a downstream injection valve 10a. An amount of fuel obtained by subtracting from the fuel amount TinTH the amount of fuel that adheres to the inner wall downstream from the throttle valve 9 is added to the amount of fuel that flows into the engine of the amount of fuel that adheres to the inner wall downstream from the throttle valve 9. A fuel injection amount of each injection valve is determined so that this total sum corresponds to an amount of fuel required by a cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an engine, and more particularly to a fuel injection control device for an engine having one fuel injection valve upstream and one downstream of a throttle valve provided in an intake pipe. About.

[0002]

2. Description of the Related Art There is known an engine control device in which a fuel injection valve is disposed upstream and downstream of a throttle valve. For example, the control device described in Japanese Patent Application Laid-Open No. 6-102999 injects fuel only from the downstream fuel injection valve in the idle rotation range, while in the idle rotation range, the fuel on the upstream side depends on the state of the engine. Inject from the injection valve. When shifting from the idle rotation range to outside the idle rotation range, the injection amount of the downstream injection valve is gradually reduced toward the target value. Further, the injection amount of the downstream injection valve is determined in consideration of the amount of the fuel injected from the upstream injection valve that adheres to the intake pipe wall surface.

Further, a fuel injection control device for an engine having a single fuel injection valve has been proposed in which the fuel injection amount is corrected in consideration of the amount of fuel adhering to the inner wall of an intake pipe (see, for example, Japanese Patent Application Laid-Open No. H11-157,837). JP-A-7-247892 and JP-A-5-340285). In particular, the latter discloses control in the case of performing two fuel injections (split injections) in one cycle.

[0004]

According to the above-mentioned control device, although the adhesion of the wall surface upstream of the throttle valve is taken into consideration, the amount of the adhesion is not estimated. Therefore, it is insufficient from the viewpoint of highly accurate control of the target air-fuel ratio, and as a result, it has been difficult to achieve both drivability (running performance) and improved fuel efficiency. Further, in order to improve the responsiveness to changes in the engine state and the throttle opening, the number of parameter settings increases, and complications cannot be avoided.

On the other hand, in an example of a fuel injection control device for an engine having a single fuel injection valve, the amount of fuel adhesion is estimated. However, since it is based on a single fuel injection valve, it is considered to be applied to a complicated system that has fuel injection valves upstream and downstream of the throttle valve and that estimates the amount of fuel adhesion upstream and downstream of the throttle valve. Had not been.

The present invention solves the above-mentioned problems, and estimates the amount of fuel adhering to the wall surface both upstream and downstream of the throttle valve,
An object of the present invention is to provide a fuel injection control device for an engine that can determine a fuel supply amount with high accuracy.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, fuel injected from an upstream injection valve and a downstream injection valve adheres to an inner wall of an intake pipe, and then separates and is supplied to an engine. Means for calculating the amount of fuel to be sent in accordance with a preset adhesion rate and separation rate, and the upstream injection valve so that the fuel supply amount including the fuel amount corresponds to the required fuel amount of the engine. The first feature is that the fuel injection amount of each of the and the downstream injection valve is determined.

Further, according to the present invention, of the fuel injected from the upstream injection valve and flowing to the downstream of the throttle valve and the fuel injected from the upstream injection valve, the fuel is deposited on the inner wall of the intake pipe upstream of the throttle valve and then separated. The amount of fuel obtained by subtracting the fuel adhering to the intake pipe inner wall downstream of the throttle valve from the sum of the fuel flowing downstream of the throttle valve and the fuel injected from the downstream injection valve, and adhering to the intake pipe inner wall downstream of the throttle valve. The sum of the amount of fuel accumulated and the amount of fuel flowing into the engine corresponds to the required fuel amount of the engine.
A second feature is that the fuel injection amount of each of the upstream injection valve and the downstream injection valve is determined.

According to the first and second features, the target air-fuel ratio required by the engine is taken into consideration, of the fuel injected from the plurality of injectors, which is directly or indirectly supplied to the cylinder. And an appropriate amount of fuel can be supplied. In particular, of the fuel injected from the upstream injection valve, the fuel injection amount is determined in consideration of the fuel that adheres to and separates from the intake pipe wall downstream of the throttle valve.

In addition, the present invention is characterized in that, of the fuel injected from the upstream injection valve and directly flowing into the engine and the fuel injected from the upstream injection valve, the fuel is deposited on the inner wall of the intake pipe, then separated and indirectly flows into the engine. Of the fuel that flows from the downstream injection valve and directly flows into the engine, and the fuel that is injected from the downstream injection valve and accumulates on the inner wall of the intake pipe and then separates and indirectly flows into the engine. A third feature is that the fuel injection amount of each of the upstream injection valve and the downstream injection valve is determined so that the sum of the amounts corresponds to the required fuel amount of the engine.

According to the third feature, although the fuel injected from the individual injection valves and adheres to the inner wall of the intake pipe and departs therefrom is taken into consideration, the upstream injection valve and the downstream injection valve are mutually separated from each other. The amount of fuel that is injected and adheres to and separates from the intake pipe wall is not considered. Therefore, there is an advantage that the process of calculating the injection amount is simplified.

Further, according to the present invention, there is provided a pressure detecting means for detecting a fuel supply pressure for each of an upstream injection valve and a downstream injection valve, and the fuel supply pressure for determining the fuel injection amount of each of the upstream injection valve and the downstream injection valve. Correction means for correcting the fuel injection amount of the injector with the higher fuel supply pressure to be shorter than the fuel injection amount of the injector with the lower fuel supply pressure in accordance with There are four features.

According to the fourth feature, it is possible to supply the fuel with higher accuracy in consideration of the difference in the fuel supply pressure depending on the surrounding environment where the upstream injection valve and the downstream injection valve are respectively arranged. it can.

Further, the present invention has a fifth feature in that the required amount of the engine includes an acceleration correction amount, and the fuel injection is performed in accordance with the fuel injection amount of each of the upstream injection valve and the downstream injection valve. A sixth feature resides in that a means for calculating time and a means for performing correction based on the injection amount per unit time of each injection valve in calculating the fuel injection time are provided.

According to the fifth feature, drivability during acceleration can be improved. According to the sixth feature, the fuel injection amount can be determined according to the respective characteristics of the upstream injection valve and the downstream injection valve.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 2 is a main part configuration diagram of an engine incorporating the fuel injection control device according to one embodiment of the present invention. In the figure, an intake port 3 and an exhaust port 4 are opened in a combustion chamber 2 of a cylinder (hereinafter also referred to as a “cylinder”) 1, and an intake valve 5 and an exhaust valve 6 are provided in each of the ports 3, 4. And a spark plug 7 is provided.
An ignition coil 23 is connected to the ignition plug 7.

The intake passage 8 communicating with the intake port 3 has a throttle valve 9 for adjusting the intake air amount according to the opening degree θTH, and a fuel injection valve provided upstream of the throttle valve 9 (hereinafter referred to as an “upstream injection valve”). ), A fuel injection valve (hereinafter referred to as a “downstream injection valve”) 10 a provided downstream, and a throttle sensor 11 and a negative pressure sensor 12 for detecting the throttle opening θTH. At the end of the intake passage 8, an air cleaner 13 is provided.
An air filter 14 is provided in 3, and outside air is taken into the intake passage 8 through the air filter 14. Further, an intake air temperature sensor 15 is provided in the air cleaner 13.

A piston 16 is provided in the cylinder 1. A crankshaft 18 connected to the piston 16 via a connecting rod 17 detects a rotation angle of the crank and outputs a crank pulse at every predetermined crank angle. A crank angle sensor 19 is arranged to face the other. Further, a vehicle speed sensor 21 is disposed to face a rotating body 20 such as a gear that rotates while being connected to the crankshaft 18.

In order to open and close the intake valve 5 and the exhaust valve 6,
Cams 51 and 61 are provided, respectively. These cams 5
Reference numerals 1 and 61 rotate in conjunction with rotation transmitted from the crankshaft 18 via a gear train (not shown). The cam 61
A cam angle sensor 25 for detecting the rotation angle position is provided.

A water temperature sensor 22 for detecting the temperature of the cooling water representing the engine temperature is provided in a water jacket formed around the cylinder 1. Further, an atmospheric pressure sensor 26 is provided at an appropriate position.

The control device 24 is a microcomputer including a CPU and a memory, and has an interface such as an input / output port and an A / D converter, and obtains operating power from a battery (not shown). The output of each sensor is taken into the control device 24 through the input port. In addition, a drive signal is output to the upstream injection valve 10, the downstream injection valve 10a, and the ignition plug 7 according to the processing result based on the input signal from each sensor. The drive signal (injection signal) for the upstream and downstream injection valves 10, 10a is a pulse signal having a pulse width corresponding to the injection amount.
The valve is opened for a time corresponding to the pulse width, and fuel is injected into the intake passage 8.

The entire amount of the fuel injected by the upstream and downstream injection valves 10 and 10a is not directly supplied to the combustion chamber 2, but
A part of the fuel is once attached to the inner wall of the intake passage 8 and then supplied to the combustion chamber 2 therefrom. What is injected from the upstream injection valve 10 and adheres to the inner wall on the upstream side of the throttle valve 9 adheres to the downstream inner wall together with a part of the fuel injected from the downstream injection valve 10a. May be sent to

Therefore, in the present embodiment, the throttle valve 9
The downstream wall fuel adhesion amount and the wall fuel adhesion amount upstream of the throttle valve 9 are estimated. In consideration of these estimated wall fuel adhesion amounts, the upstream and downstream injection valves 10, 10a
Is calculated. Specifically, the throttle valve 9
Deposition rate for estimating wall fuel deposition on the upstream and downstream of the
The fuel injection amount is calculated using the ratio of the fuel that has separated from the fuel deposited on the wall surface and flows downstream therefrom, that is, the separation rate. These adhesion rates and separation rates are functions of the engine state, that is, the throttle opening θTH and the engine speed Ne, and are calculated and set based on the experimental results.

FIG. 3 is a schematic view of the vicinity of the throttle valve 9, that is, the throttle body, showing a dynamic model of the fuel injected into the intake passage 8. In the figure, the fuel supply amounts of the upstream injection valve 10 and the downstream injection valve 10a are controlled such that the fuel amount “TCYL” matches the total required fuel amount Tin.
Total required fuel amount of upstream injection valve 10 and downstream injection valve 10a
Tin is set to “1”, and the injection ratio of the fuel supplied from the downstream injection valve 10 a to the cylinder 1, that is, the downstream injection ratio is set to “RL”.
When “U” is set, the injection ratio of the fuel supplied from the upstream injection valve 10 to the cylinder 1, that is, the upstream injection ratio is “1-RLU”.
It is. Further, when the proportion of the total injected fuel amount of the upstream injection valve 10 that directly shifts to the downstream of the throttle valve 9, that is, the upstream direct rate is “CFW”, the proportion of the fuel adhering to the upstream wall surface of the throttle valve 9, Rate is the upstream adhesion rate
CFW ".

On the other hand, the upstream direct ratio “CF
The fuel directly fed to the downstream side of the throttle valve 9 at W and the fuel that once adheres to the upstream wall surface and then separates from the wall surface and flows downstream are indirectly integrated with the injected fuel of the downstream injection valve 10a. Is fed downstream. Here, the ratio of the fuel separated from the wall surface and fed downstream, that is, the “detachment rate”
Is defined as the upstream indirect ratio “DFW”.

Downstream of the throttle valve 9 is an upstream injection valve 1
There is fuel directly or indirectly flowing from zero and fuel injected from the downstream injection valve 10a. This amount of fuel is defined as the downstream fuel amount TinTH. Of these, intake port 3
The fuel that goes directly to
The fuel adhering to the wall surface downstream of the throttle valve 9 is calculated by the downstream adhesion rate “1-AFW” as the “adhesion rate”.

Further, the fuel adhering to the upstream wall surface, that is, the upstream adhering amount is defined as "TWPU", and the fuel adhering to the downstream wall surface, that is, the downstream adhering amount is defined as "TWPL". From the downstream adhering amount "TWPL" to the intake port 3 side, The rate of feed, or "leaving rate", is defined as the downstream indirect rate "BFW". The fuel amount calculated based on the downstream direct rate "AFW" and the downstream indirect rate "BFW" is the fuel amount "TCYL" fed to the cylinder 1, and this fuel amount "TCYL" is the required fuel amount. The fuel supply amount is controlled so as to match.

From the above definition, the fuel demand of cylinder 1 "TC
YL '', the downstream adhesion amount `` TWPL '' used in the next calculation, the upstream adhesion amount `` TWPU '', and the downstream fuel amount `` TinTH '' used in the next calculation are calculated by the following equations (Equation 1) to (Equation 4). Are calculated respectively. TCYL = AFW × TinTH + BFW × TWPL (Equation 1). TWPL = (1-AF
W) × TinTH + (1-BFW) × TWPL (Equation 2). TWPU = (1-RLU) × (1-C
FW) × Tin (TOTAL) + (1-CFW) × TWPU (Equation 3). TinTH = Tin (TO
TAL) × RLU + CFW × (1-RLU) × Tin (TOTAL) + DFW × TWPU ...
Four).

FIG. 4 is a block diagram corresponding to the above equations (Equations 1) to (Equation 4). Further, a block diagram of an arithmetic function for calculating the total injection amount Tin (TOTAL) for supplying the required fuel amount “TCYL” without excess or deficiency can be represented as shown in FIG. 5 based on FIG.

Next, a control model in which acceleration correction is performed to ensure drivability in a transient state will be described. In this control model, the required fuel amount not including the acceleration correction amount is defined as “TCYL (MAP)”, and the required fuel amount including the acceleration correction amount is defined as “TCYL (TACC)”. Fuel demand TCYL (TAC
C) is a value obtained by adding the acceleration correction amount TACC to the fuel demand amount TCYL (MAP).

Here, the upstream injection valve 10 controls the downstream injection ratio RLU of the fuel demand TCYL (MAP) not including the acceleration correction amount.
And contributes to the fuel injection of the amount obtained by subtracting the amount corresponding to. On the other hand, the downstream injection valve 10a has a fuel demand TC including an acceleration correction amount.
Fuel injection is performed in an amount obtained by subtracting the contribution of the upstream injection valve 10 from YL (TACC).

First, the fuel demand TC which does not include the acceleration correction amount TC
The fuel amount TinTH (MAP) that must be present downstream of the throttle valve 9 to correspond to YL (MAP) is expressed by the following equation (Equation 5). TinTH (MAP) = (TCYL (MAP) -BFW × TWPL) / AFW ... (expression
Five).

When the fuel amount TinTH (MAP) is expressed in relation to the injection amount of the upstream injection valve 10 and the injection amount of the downstream injection valve 10a, the following expression (expression) is obtained.
It looks like 6). TinTH (MAP) = Tin (total) × RLU + CFW × (1
-RLU) × Tin (TOTAL) + DFW × TWPU ... (Equation 6).

According to (Equation 5) and (Equation 6), the total injection amount Tin (TO
TAL) is represented by the following equation (Equation 7). Tin (TOTAL) = [(TCYL (MAP)-
BFW × TWPL) / AFW-DFW × TWPU] / [RLU + (1-RLU) × CFW]… (Equation
7). Also, according to (Equation 7), the upstream injection amount Tin (Upper) is calculated by the following equation
(Expression 8). Tin (Upper) = (1-RLU) / [RLU + (1-RLU) ×
CFW] [(1 / AFW) (TCYL (MAP) -BFW × TWPL) -DFW × TWPU]… (expression
8).

The downstream injection amount is calculated as follows.
First, the fuel amount TinTH (TACC) that must be present downstream of the throttle valve 9 in order to correspond to the required fuel amount TCYL (TACC) including the acceleration correction amount is expressed by the following equation (Equation 9). TinTH (TA
CC) = (TCYL (TACC) -BFW × TWPL) / AFW ... (Equation 9).

Of the fuel existing upstream of the throttle valve 9, the amount of fuel Tin (Uppe
r) is represented by the following equation (Equation 10). TinTH (Upper) = CFW × Tin (Up
per) + DFW × TWPU ... (Equation 10).

According to (Equation 9) and (Equation 10), the downstream injection amount Tin
(Lower) is represented by the following equation (Equation 11). Tin (Lower) = TinTH (TA
CC) -TinTH (Upper) = (TCYL (MAP) -BFW × TWPL) / AFW- (CFW × T
in (Upper) + DFW × TWPU) ... (Equation 11).

The upstream injection valve 10 and the downstream injection valve 1
If the injection amount per unit time of 0a is different, the fuel injection ratio of the upstream injection valve 10 to the downstream injection valve 10a is set in advance, and the fuel injection time is calculated according to the ratio.
The fuel injection amount ratio KTin (Upper) is the upstream injection amount Tin (Upper)
Can be tabulated as a function of FIG. 6 is an example of a table in which the relationship between the fuel injection amount ratio KTin (Upper) and the upstream injection amount Tin (Upper) is set.

The injection time Tout (Upper) of the upstream injection valve 10 is calculated by the following equation (Equation 12). Tout (Upper) = Tin (Upper)
× KTin (Upper) + TiVB (Upper) ... (Equation 12). TiVB (Upper) is the invalid injection time of the upstream injection valve 10.

The injection time Tout (Lower) of the downstream injection valve 10a
Is calculated by the following equation (Equation 13). Tout (Lower) = Tin (Lowe
r) + TiVB (Lower) ... (Equation 13). TiVB (Lower) is downstream injection valve 1
0a is an invalid injection time.

Fuel adhering to the upstream wall surface (upstream adhering amount TWP
U) and the amount of fuel deposited on the downstream wall (downstream deposition amount TWPL), taking into account the amount removed in this cycle and the newly deposited fuel, consider the downstream deposition amount TWPL and the upstream deposition amount used in the next cycle. The adhesion amount TWPU is calculated.

First, from the above (Equation 2), the downstream adhesion amount TWPL carried over to the next cycle is calculated by the following equation (Equation 14).
Next time TWPL = (1-RLU) × TinTH (TACC) + (1-BFW) × TWPL ... (Equation 1
Four). Further, since the injection by the upstream injection valve 10 does not include the acceleration correction amount, the upstream adhesion amount TW carried over to the next cycle is not included.
PU is calculated using the same equation (Equation 15) as the above (Equation 3).
Next TWPU = (1-RLU) × (1-CFW) × Tin (TOTAL) + (1-CFW) × TWP
U ... (Equation 15).

Next, fuel injection control based on the above control model will be described with reference to the flowchart of FIG. In step S1 of FIG. 7, it is determined whether or not it is a scheduled calculation timing. This determination is made based on the crank position detected based on the detection signals of the crank angle sensor 19 and the cam angle sensor 25. The calculation timing is set several times in one cycle (for example, every crank angle of 180 °). When the calculation timing has come, the routine proceeds to step S2, where the engine speed Ne is read. The engine speed Ne is detected based on a detection signal of the crank angle sensor 19. In step S3, the throttle opening θTH is read. In step S4, a change amount DθTH of the throttle opening θTH from the previous calculation timing is calculated.

In step S5, a basic injection amount TCYL0 is calculated. The basic injection amount TCYL0 is calculated based on the engine speed Ne and the throttle opening θTH. In step S6, the acceleration correction amount is calculated based on the throttle opening change amount DθTH.
Calculate TACC. Basic injection amount TCYL0 and acceleration correction amount TACC
Is the relationship between the basic injection amount TCYL0 and the engine speed Ne and the throttle opening θTH, and the throttle opening change DθTH
The relationship between the acceleration correction amount TACC and the table can be obtained by searching a table or the like set in advance based on experimental results and calculations.

In step S7, a correction term is calculated based on the detection signals of the atmospheric pressure sensor 26, the intake air temperature sensor 15, the water temperature sensor 22, and the like, and a correction coefficient K summing up these is calculated.

In step S8, a required fuel amount TCYL (MAP) not including the acceleration correction amount TACC and a required fuel amount TCYL (TACC) including the acceleration correction amount TACC are calculated. The required fuel amount TCYL (MAP) is obtained by multiplying the basic injection amount TCYL0 by the correction coefficient K. On the other hand, the fuel correction amount TCYL (TACC) is obtained by adding the acceleration correction amount TACC to the fuel supply amount TCYL (MAP) not including the acceleration correction amount.

In step S9, the upstream injection amount Tin (Upper)
And the downstream injection amount Tin (Lower) are calculated. These are
It is calculated using (Equation 8) and (Equation 11).

In step S10, the above upstream injection amount Tin
In order to supply (Upper) and the downstream injection amount Tin (Lower), the fuel injection time of each of the upstream and downstream is calculated. Generally, since the injection amount per unit time of the upstream injection valve 10 and the downstream injection valve 10a is different, in step S10, each fuel injection time To is calculated using (Equation 12) and (Equation 13).
Calculate ut (Upper) and Tout (Lower).

In step S11, it is determined whether or not it is the injection timing of the upstream injection valve 10. If it is determined that it is the injection timing of the upstream injection valve 10, the process proceeds to step S12, and the time calculated in step S10 is used for the upstream injection valve 10
Drive. In step S13, the amount of fuel attached to the upstream wall surface by the current fuel injection, that is, the upstream attachment amount TWPU
Is calculated and stored as a value for the next calculation.

In step S14, it is determined whether or not it is the injection timing of the downstream injection valve 10a. If it is determined that it is the injection timing of the downstream injection valve 10a, step S15
To drive the downstream injection valve 10 for the time calculated in step S10. In step S16, the amount of fuel attached to the downstream wall surface by the current fuel injection, that is, the amount
Calculate TWPL and store it as the value for the next calculation.

By performing the above processing for each cycle and for each cylinder in a plurality of cylinders, it is possible to supply fuel (cylinder required amount) as required for cylinder 1 determined in consideration of drivability and fuel efficiency. it can.

The upstream injection valve 10 and the downstream injection valve 10a
The fuel pressure may differ from the surrounding atmosphere due to the difference in the surrounding environment in which is disposed. For example, downstream injection valve 1
The fuel pressure of the upstream injection valve 10 may be lower than 0a. In addition to the above-described control, by performing a correction in consideration of the difference in the fuel pressure, it is possible to perform more accurate fuel supply with respect to the cylinder demand. Specifically, the upstream injection valve 1
A sensor for detecting the fuel pressure of 0 and the downstream injection valve 10a is provided, and the injection time is corrected according to the output of this sensor. For example, the injection time of the injection valve with the higher fuel pressure is corrected to be shorter than the injection time of the injection valve with the lower fuel pressure.

FIG. 1 is a block diagram showing the main functions of the fuel injection control device according to the present embodiment. In the figure,
The direct component calculation unit 28 estimates, of the fuel injected from the upstream injection valve 10, the fuel that does not adhere to the inner wall of the intake pipe and directly flows downstream of the throttle valve 9. The indirect component calculation unit 29 estimates, of the fuel injected from the upstream injection valve 10, the fuel that adheres to the inner wall of the intake pipe, then separates therefrom and indirectly flows downstream of the throttle valve 9.

The downstream fuel calculator 30 sums the estimated fuel amount calculated by the direct component calculator 28 and the indirect component calculator 29 and the amount of fuel injected from the downstream injection valve 10a. The downstream indirect component calculation unit 31 estimates, of the fuel summed up by the downstream fuel calculation unit 30, the fuel that adheres to the inner wall of the intake pipe, then separates therefrom and indirectly flows into the cylinder 1.

The downstream direct component calculating unit 32 calculates the downstream indirect component calculating unit 31 of the fuel totaled by the downstream fuel calculating unit 30.
By subtracting the fuel amount calculated in the above, the fuel directly flowing into the cylinder 1 is estimated.

The summing unit 33 sums up the fuel amounts calculated by the downstream direct component calculating unit 32 and the downstream indirect component calculating unit 31. The comparison unit 34 calculates the calculation result of the summation unit 33, that is, the cylinder 1
Estimated amount of fuel flowing into the cylinder and the required amount of cylinder TC
Compare with YL. When the required amount TCYL is smaller, an instruction is issued to extend the fuel injection time by the upstream injection valve 10 and the downstream injection valve 10a. When the required amount TCYL is larger, the upstream injection valve 10 and the downstream injection valve are output. An instruction is output to shorten the fuel injection time by 10a.

In the above-described embodiment, the fuel injected from the upstream injection valve 10 and the downstream injection valve 10a is taken into consideration in consideration of the amount of fuel injected from the upstream injection valve 10 adhering to the inner wall of the intake pipe downstream of the throttle valve 9 and separating therefrom. The amount was calculated. However, the portion of the fuel injected from the upstream injection valve 10 adhering to the inner wall of the intake pipe downstream of the throttle valve 9 is not considered, and the amount of fuel injected from the upstream injection valve 10 and adhering to the inner wall upstream of the throttle valve 9 is considered. The amount of separation from the downstream injection valve 10
The calculation may be made by separately considering the amount of the fuel injected from a and attached to the inner wall on the downstream side of the throttle valve 9 and the amount separated from the inner wall.

That is, of the fuel injected directly from the upstream injection valve 10 and directly flowing into the engine and the fuel injected from the upstream injection valve, the fuel is deposited on the inner wall of the intake pipe upstream of the throttle valve 9 and then separated and removed from the engine. The fuel flowing indirectly into the tank is added to the first amount. On the other hand, the downstream injection valve 10a
Of the fuel injected directly from the engine into the engine and the fuel injected from the downstream injection valve, the fuel that accumulates on the inner wall of the intake pipe downstream of the throttle valve 9 and then separates and indirectly flows into the engine is added. This is the second amount. And
The fuel injection amount of each of the upstream injection valve 10 and the downstream injection valve 10a is determined such that the sum of the first amount and the second amount corresponds to the required fuel amount of the engine, that is, the required cylinder amount TCYL.

In this embodiment, one fuel injection valve is provided upstream and downstream of the throttle valve 9, respectively. However, the present invention is not limited to this, and one fuel injection valve is provided at least upstream and downstream of the throttle valve 9. It can be suitably adopted for the engines arranged one by one.

[0060]

As is apparent from the above description, according to the first to sixth aspects of the present invention, the fuel adhering to the wall surface downstream of the throttle valve and the fuel separated from and fed therefrom are considered. Thus, the fuel injection amounts of the plurality of fuel injection valves are determined. Therefore, the fuel supply can be controlled with high accuracy with respect to the target air-fuel ratio, which can contribute to improvement in drivability and improvement in fuel efficiency. In particular, according to the first and second aspects of the present invention, of the fuel injected from the upstream injection valve, the fuel injection amount is determined in consideration of fuel that adheres to and separates from the intake pipe wall downstream of the throttle valve. .

According to the third aspect of the present invention, the fuel injection amount is calculated without considering the amount of the upstream injection valve and the downstream injection valve which are injected from each other and adhere to and separate from the intake pipe wall surface. Therefore, there is an advantage that the calculation process is simplified.

Further, according to the fourth aspect of the present invention, the fuel supply amount can be determined with higher accuracy in consideration of the fuel supply pressure due to the installation state of each injection valve.

According to the invention of claim 5, drivability during acceleration can be improved. Further, according to the invention of claim 6, the fuel injection amount can be determined according to the respective characteristics of the upstream injection valve and the downstream injection valve.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a main part of a fuel injection control device according to an embodiment of the present invention.

FIG. 2 is a main part configuration diagram of an engine including the fuel injection control device of the present invention.

FIG. 3 is a schematic diagram of a throttle body showing a dynamic model of fuel injected into an intake passage.

FIG. 4 is a block diagram corresponding to a dynamic model near a throttle valve.

FIG. 5 is a block diagram of a calculation function for calculating a total injection amount by an injection valve.

FIG. 6: Fuel injection amount ratio KTin (Upper) and upstream injection amount Tin
This is a table in which the relationship with (Upper) is set.

FIG. 7 is a flowchart showing a fuel injection control process. 4 is a timing chart showing the calculation of fuel injection time and the timing of fuel injection.

[Explanation of symbols]

9: throttle valve, 10: upstream injection valve, 10a: downstream injection valve, 11: throttle sensor, 19: rotation angle sensor, 24: control device, 25: cam angle sensor,
26 ... Atmosphere sensor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 69/00 F02M 69/00 350L 350P (72) Inventor Toru Takeda 1-4-1 Chuo, Wako-shi, Saitama No. F-term in Honda R & D Co., Ltd. (reference) 3G084 BA03 BA05 BA13 BA14 CA04 CA05 DA04 EB08 FA01 FA02 FA10 FA20 FA33 FA38 FA39 3G301 HA01 JA03 KA11 LA01 LB02 LB03 LB06 MA14 NC02 PA09Z PA10Z PA11Z PE01Z PE08Z

Claims (6)

[Claims] At least one upstream injection valve disposed upstream of a throttle valve and at least one downstream injection valve disposed downstream of a throttle valve are provided.
In the fuel injection control device for the engine provided with each one, the amount of the fuel injected from the upstream injection valve and the downstream injection valve that adheres to the inner wall of the intake pipe, and then separates and is fed into the engine, Means for calculating in accordance with a predetermined adhesion rate and separation rate, wherein the fuel injection of each of the upstream injection valve and the downstream injection valve is performed so that the fuel supply amount including the fuel amount corresponds to the required fuel amount of the engine. An engine fuel injection control device for determining an amount. 2. The method according to claim 1, wherein an upstream injection valve disposed upstream of the throttle valve and a downstream injection valve disposed downstream of the throttle valve are at least one.
In the fuel injection control device for an internal combustion engine, the fuel injected from the upstream injection valve and flows into the downstream of the throttle valve is injected from the upstream injection valve, deposits on the inner wall of the intake pipe upstream of the throttle valve, and then separates. First calculating means for calculating an amount of fuel obtained by subtracting fuel adhering to the inner wall of the intake pipe downstream of the throttle valve from the sum of fuel flowing downstream of the throttle valve and fuel injected from the downstream injection valve; Second calculating means for summing the amount of fuel calculated by the means and the amount of fuel flowing into the engine side among the fuel adhering to the inner wall of the intake pipe downstream of the throttle valve, and calculating by the second calculating means. Calculating means for determining the fuel injection amount of each of the upstream injection valve and the downstream injection valve such that the amount of fuel corresponds to the required fuel amount of the engine. The fuel injection control apparatus for an engine according to. 3. An at least one upstream injection valve disposed upstream of the throttle valve and at least one downstream injection valve disposed downstream of the throttle valve.
In the fuel injection control device for an internal combustion engine, each of the fuel injected from the upstream injection valve and directly flowing into the engine and the fuel injected from the upstream injection valve accumulates on the inner wall of the intake pipe and then separates. Of the amount of fuel indirectly flowing into the engine, the fuel injected from the downstream injection valve and directly flowing into the engine, and the fuel injected from the downstream injection valve, the fuel is deposited on the inner wall of the intake pipe, then separated and indirectly transferred to the engine. A fuel injection control device for an engine, wherein a fuel injection amount of each of the upstream injection valve and the downstream injection valve is determined such that a sum of the amount of fuel flowing in and the amount of fuel corresponds to a required fuel amount of the engine. 4. A pressure detecting means for detecting a fuel supply pressure for each of the upstream injection valve and the downstream injection valve, and, when determining the fuel injection amount of each of the upstream injection valve and the downstream injection valve, according to the fuel supply pressure. Correction means for correcting the fuel injection amount of the injection valve having the higher fuel supply pressure to be shorter than the fuel injection amount of the injection valve having the lower fuel supply pressure. Claim 1 to
The fuel injection control device for an engine according to claim 3. 5. The fuel injection control device for an engine according to claim 1, wherein the required amount of the engine includes an acceleration correction amount. 6. A means for calculating a fuel injection time according to a fuel injection amount of each of the upstream injection valve and the downstream injection valve, and calculating the fuel injection time based on an injection amount per unit time of each injection valve. The fuel injection control device for an engine according to any one of claims 1 to 5, further comprising means for performing correction.