JPH05340285A - Engine fuel controller - Google Patents

Abstract

(57) [Summary] [Purpose] In a fuel control device for an engine in which the fuel injection amount is set based on the direct entry rate (adhesion rate) and the carry-out rate, the number of fuel injections per cycle or the fuel injection timing is set. (EN) A fuel control device capable of accurately supplying a fuel of a required fuel amount to a combustion chamber regardless of the above. [Structure] In a rotation range of about 1000 rpm or more, leading injection and trailing injection are performed, fuel vaporization and atomization are promoted, and fuel distribution is made uniform. Then, the control unit 18 estimates the direct entry ratio and the removal ratio, and fuel corresponding to the intake air amount is supplied to the combustion chamber 3 based on the estimated values. here,
The direct entry rate estimated value and the carry-away rate estimated value are corrected in accordance with the division ratio, and fuel commensurate with the intake air amount is always supplied to the combustion chamber 3 regardless of the presence or absence of division or the magnitude of the division ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine fuel control system.

[0002]

2. Description of the Related Art Generally, in a fuel injection type gasoline engine, fuel is injected from a fuel injection valve into an intake passage (intake port). However, all the injected fuel is directly injected into a combustion chamber. A part of the liquid is not brought in and adheres to the wall of the intake passage in a liquid state, so that the adhered fuel always stays in the intake passage during engine operation. Then, the attached fuel is gradually vaporized or is carried away to the combustion chamber in a liquid state. Therefore, in each cycle, the fuel that is directly carried in from the fuel injection valve (direct injection amount) and the fuel that is taken away from the intake passage wall (takeaway amount) are supplied to the combustion chamber in each cycle. Therefore, in each cycle, the fuel injection amount from the fuel injection valve and the actual fuel supply amount to the combustion chamber basically do not match.

Therefore, in each cycle, the air-fuel ratio (A / F) of the air-fuel mixture is changed to the target air-fuel ratio (for example, even if the required amount of fuel (fuel demand amount) is injected according to the intake air amount. , A / F = 14.7) in many cases. For example, at the time of acceleration, the intake air amount increases sharply and the fuel demand increases accordingly, but the carry-out amount does not increase suddenly. The problem arises that the quality becomes worse. On the contrary, at the time of deceleration, the intake air amount sharply decreases and the fuel demand amount accordingly sharply decreases, but the carry-out amount does not suddenly decrease, so that the air-fuel mixture becomes abnormally rich. During steady operation, the fuel adhesion speed to the intake passage and the fuel removal speed from the intake passage reach an equilibrium state, and apparently the fuel injection amount and the actual fuel supply amount to the combustion chamber are almost equal. Therefore, by injecting the same amount of fuel as the required fuel amount, the air-fuel ratio will be maintained substantially at the target air-fuel ratio.

Therefore, in each cycle, of the fuel injected from the fuel injection valve, the ratio of the fuel directly introduced into the combustion chamber (direct injection ratio) or the ratio of the fuel adhering to the intake passage (adhesion ratio) is estimated. , Of the fuel adhering to the intake passage wall, the ratio of the fuel carried away to the combustion chamber in the cycle (take-away rate) is estimated, and based on the direct entry rate (adhesion rate) and the take-away rate, Of the fuel injected in the cycle, the amount that is directly brought into the combustion chamber (the amount of direct injection),
A fuel control device configured to set the fuel injection amount so that the total amount of the fuel adhering to the intake passage wall that is taken away in the cycle (takeaway amount) matches the fuel demand amount in the cycle. Have been proposed (for example, Japanese Patent Publication No. 3-
No. 59255). Then, in such a conventional fuel control device, the behavior of the fuel injected from the fuel injection valve and the behavior of the adhered fuel are theoretically or experimentally determined based on the engine load, the engine speed, the engine water temperature, the intake flow velocity, and the like. It is clarified and the direct entry rate (adhesion rate) or carry-out rate is estimated based on this.

By the way, generally, in a fuel injection type engine in which fuel is intermittently injected from a fuel injection valve in each cycle, as compared with a carburetor type engine or the like in which fuel is constantly sucked out during intake. However, there are problems that the vaporization and atomization of the fuel in the intake passage are poor, and the fuel distribution in the combustion chamber becomes uneven. Therefore, a fuel injection engine has been proposed in which fuel is injected a plurality of times in each cycle to promote vaporization and atomization of the fuel and to make the fuel distribution in the combustion chamber uniform.

[0006]

However, the fuel injection amount is calculated based on the direct entry rate estimation value (adhesion rate estimation value) and the take-away rate estimation value as disclosed in Japanese Patent Publication No. 3-59255, for example. In a fuel injection engine provided with a fuel control device for setting, if fuel injection is performed a plurality of times in each cycle, the fuel injected from the fuel injection valve and the fuel adhering to the intake passage wall interfere with each other. However, it becomes impossible to accurately estimate the direct injection ratio, the amount of fuel adhered or the carry-out ratio, and it becomes impossible to maintain the air-fuel ratio at the target air-fuel ratio. Further, in an engine in which the fuel injection timing is changed according to the operating state, the behavior of the fuel changes when the injection timing is changed, and the estimation accuracy of the direct injection rate, the fuel attachment rate or the carry-out rate decreases. The problem arises. Furthermore, there is a problem that the direct entry ratio or the carry-out ratio also changes depending on the time interval between fuel injections.

The present invention has been made in order to solve the above-mentioned conventional problems, and fuel control of an engine in which the fuel injection amount is set based on the direct entry rate (adhesion rate) and the take-away rate. (EN) Provided is a fuel control device capable of accurately supplying a required amount of fuel to a combustion chamber regardless of the number of fuel injections per cycle, the fuel injection timing, or the time interval of fuel injection. To aim.

[0008]

In order to achieve the above object, the first aspect of the present invention is, in each cycle, the proportion of fuel directly introduced into the combustion chamber among the fuel injected from the fuel injection valve (direct injection rate). In addition to estimating the ratio of the fuel adhered to the intake passage wall to the combustion chamber in the cycle (take-away rate), based on the direct entry rate and the take-away rate, The total amount of the fuel injected in the cycle that is directly carried into the combustion chamber and the total amount of the fuel that adheres to the intake passage wall that is carried away into the combustion chamber in the cycle are the required fuel amount in the cycle. In the fuel control device for the engine, which is provided with the fuel injection amount setting means for setting the fuel injection amount so as to match with, the fuel injection pattern is a single injection pattern in which injection is performed only once per cycle, Injection pattern setting means capable of setting a plurality of injection patterns for performing a plurality of injections per cycle, and when a plurality of injection patterns are set by the injection pattern setting means, when a single injection pattern is set And an estimated value correction means for correcting the direct entry rate estimated value and the carry-away rate estimated value to the decreasing side.

A second aspect of the present invention estimates the proportion of fuel that is directly introduced into the combustion chamber (direct injection rate) of the fuel injected from the fuel injection valve in each cycle, and adheres to the intake passage wall. Estimating the proportion of fuel that is carried away to the combustion chamber in the cycle (take-away rate), and based on the direct entry rate and the take-away rate, directly in the combustion chamber of the fuel injected in the cycle And the amount brought into
Fuel injection amount setting means is provided for setting the fuel injection amount such that the total amount of the fuel adhering to the intake passage wall that is carried away to the combustion chamber in the cycle matches the fuel demand amount in the cycle. In the engine fuel control system,
The injection timing setting means for setting the fuel injection timing according to the operating state, and the shorter the interval between the previous fuel injection and the current fuel injection, the more the direct entry rate estimated value and the carry-away rate estimated value are corrected to the decreasing side. A fuel control device for an engine is provided, which is provided with an estimated value correction means.

A third aspect of the present invention estimates the proportion (direct entry rate) of the fuel introduced directly into the combustion chamber in the fuel injected from the fuel injection valve in each cycle, and also adheres to the intake passage wall. Estimating the proportion of fuel that is carried away to the combustion chamber in the cycle (take-away rate), and based on the direct entry rate and the take-away rate, directly in the combustion chamber of the fuel injected in the cycle And the amount brought into
Fuel injection amount setting means is provided for setting the fuel injection amount such that the total amount of the fuel adhering to the intake passage wall that is carried away to the combustion chamber in the cycle matches the fuel demand amount in the cycle. In the engine fuel control system,
An engine characterized in that an estimated value correction means is provided for correcting the direct injection rate estimated value and the carry-away rate estimated value to a decreasing side as the time interval between the previous fuel injection and the current fuel injection is shorter. The fuel control device of

[0011]

EXAMPLES Examples of the present invention will be specifically described below. <First Embodiment> As shown in FIG. 2, in a fuel injection type gasoline engine CE, when an intake valve 1 is opened, an air-fuel mixture is sucked into a combustion chamber 3 from an intake port 2 and the air-fuel mixture is drawn into a piston. It is compressed by 4 and ignited and burned by the spark plug 5, and when the exhaust valve 6 is opened, the combustion gas is discharged to the exhaust passage 8 through the exhaust port 7. The exhaust passage 8 has a catalytic converter 9 for purifying the exhaust gas.
Is installed.

In order to supply air to the engine CE (combustion chamber 3), an intake passage 11 having a downstream end communicating with the intake port 2 is provided, and the intake passage 11 is provided with intake air in order from the upstream side. A hot wire type air flow sensor 12 that detects the amount, a throttle valve 13 that is opened and closed in conjunction with an accelerator pedal (not shown), and a surge tank 14 that stabilizes the flow of intake air are provided. And
In the vicinity of the intake port 2, a fuel injection valve 15 that injects fuel into intake air in the intake passage 11 is provided so that the injection port faces the intake port 2. here,
The fuel injection amount (injection pulse width) of the fuel injection valve 15 and the injection timing are, as will be described later, the air flow sensor 1
Intake air amount Qa detected by 2 and water temperature sensor 16
Engine water temperature Tw detected by the rotation speed sensor 1
Based on the engine speed N and the like detected by 7,
Control unit 1 consisting of a microcomputer
8 is controlled. As shown in FIG. 1, the control unit 18 is a comprehensive control device for the engine CE, which includes the fuel injection amount setting means, the injection pattern setting means, and the estimated value correcting means described in claim 1. is there.

By the way, all the fuel injected from the fuel injection valve 15 into the intake passage 11 in each cycle is not directly brought into the combustion chamber 3 in the cycle, but a part of the fuel is introduced into the intake passage 11. After being attached to the inner wall, it is gradually carried away to the combustion chamber 3 in a later cycle. Therefore, the actual fuel supply amount to the combustion chamber 3 in each cycle basically does not match the fuel injection amount in the cycle. Less than,
The behavior of such fuel will be described. As shown in FIG. 3, the fuel injected from the fuel injection valve 15 into the intake passage 11 in a certain cycle is directly introduced into the combustion chamber 3 in the cycle by the amount F ₁ (hereinafter, this is a direct injection amount F ₁ a) that the partial F ₂ adhering to the inner wall of the not brought directly into the combustion chamber 3 the intake passage 11 in the cycle (hereinafter, divided it in the referred deposition fraction F _2). Therefore, the adhered amount F ₂ is accumulated on the inner wall of the intake passage 11 to form the fuel pool F ₃ .

A part of the fuel in the fuel pool F ₃ is
The vaporized or liquid state is carried away to the combustion chamber 3 by the flow of intake air or by gravity. Therefore, in the fuel supplied to the combustion chamber 3 in the cycle, the amount F ₄ carried away from the fuel pool F ₃ to the combustion chamber 3 (hereinafter, this is referred to as the carried amount F ₄ ) is added to the above-mentioned direct entry F _1. It becomes a thing. Therefore, basically, in each cycle, the sum of the direct flow-in amount F ₁ and the carry-out amount F ₄ is the fuel required according to the intake air amount in order to maintain the target air-fuel ratio (hereinafter, this is the fuel demand). If the fuel injection amount is set so as to correspond to (the amount), the air-fuel ratio can be maintained at the target air-fuel ratio.

That is, the required fuel amount is τa, the fuel injection amount is τe, the fuel holding amount of the fuel pool F ₃ (hereinafter referred to as the wet amount) is τm, and the fuel injection amount τe of the direct injection portion F ₁ is calculated. Assuming that the ratio is α (hereinafter, this is the direct entry ratio α), and the ratio of the carry-out amount F _{4 to} the wet amount τm is β (hereinafter, this is the carry-out ratio β), the following equation 1 and equation 2 It suffices to inject the fuel so as to satisfy the above condition.

[Equation 1] τa = α ・ τe + β ・ τm ……………………………………………… Equation 1

## EQU00002 ## .tau.m = (1-.alpha.). Multidot..tau.e (i-1) + (1-.beta.). Tau.m (i-1) ..... Equation 2 In addition, in Equation 2, τe (i-1) Is the previous τe,
τm (i-1) is the previous τm. Therefore, in each cycle, first, τm of this time is calculated by the equation 2, then τe is calculated by the equation 1 by using this τm, and fuel is injected by τe, the air-fuel ratio is maintained at the target air-fuel ratio. It will be. Here, α and β are set theoretically or experimentally according to the intake air amount, the water temperature, etc., as described later. The specific fuel control method will be described later in FIG.
6 and the flowchart shown in FIG.

Further, in order to promote the vaporization and atomization of the fuel and to make the fuel distribution in the combustion chamber 3 uniform, basically, the fuel injection from the fuel injection valve 15 is performed by suction, compression and 2 in 1 cycle consisting of 4 strokes of combustion and exhaust
It is designed to be divided into two times. In the following, for convenience, the fuel injection that is performed at a predetermined timing that is relatively early in one cycle is referred to as leading injection, and the fuel injection that is performed at a predetermined timing that is relatively late is referred to as trailing injection. Specifically, as shown in FIG.
Only the trailing injection is performed in the low rotation range of approximately 1000 rpm or less, and both the leading injection and the trailing injection are performed on the higher rotation side. When both injections are performed, the proportion of the leading injection in the total fuel injection amount increases as the engine speed increases.

Hereinafter, the control method of the fuel control by the control unit 18 will be described according to the flowcharts shown in FIGS. 5 and 6 and with reference to FIGS. When the control is started, first, at step # 1, the intake air amount Qa detected by the air flow sensor 12, the engine speed N detected by the rotation speed sensor 17, and the cooling water temperature detected by the water temperature sensor 16. Tw is read as control information. In step # 2, the intake charge amount Ce ₀ (hereinafter, referred to as a basic intake charge amount Ce ₀ ) is calculated based on the intake air amount Qa detected by the air flow sensor 12 by the following expression 3.

[Equation 3] Ce ₀ = Ka · Qa / N ……………………………………………………………………………………………………………………………………………………………………………… From KA is an ordinary conversion factor for calculating the intake charge. is there.

In step # 3, the smoothed intake charge amount Ce is calculated by performing the smoothing process on the basic intake charge amount Ce _{0 according} to the following equation (4).

[Equation 4] Ce = Kc · Ce + (1−Kc) · Ce ₀ Equation 4 Note that Kc is an ordinary smoothing coefficient and is 0 or more and 1 or less. It is a predetermined value within the range. Generally, the intake air amount Qa (airflow sensor detection value) detected by the airflow sensor 12 fluctuates drastically when viewed microscopically due to the turbulence of the airflow in the intake passage 11, and therefore, this Qa The basic intake air charge amount Ce ₀ calculated based on this also changes. Therefore, if the required fuel amount is calculated using the basic intake air charge amount Ce ₀ , the fuel control becomes unstable. Therefore, a smoothing process is performed in order to absorb the fluctuation and stabilize the fuel control.

In step # 4, the intake air amount Q at the fuel injection valve position is calculated based on the smoothed intake charge amount Ce by the following equation 5.

## EQU00005 ## Q = (1 / Ka) .Ce.N ………………………………………………………………………………………………………………………………………………………………………………………………………… The basic injection pulse width τa, that is, the fuel demand amount per cycle is calculated.

[Equation 6] τa = Kp · Cw · Ce …………………………………………………… .......................... function. It is a conversion coefficient, and Cw is a water temperature correction value.

In step # 6, the intake air amount Q and the water temperature T
Depending on w, the direct injection basic value α _L0 for the leading injection is retrieved using the map having the characteristics shown in FIG. 7, and the direct injection rate basic value α _L0 for the leading injection is searched for using the map having the characteristics shown in FIG. The carry-out rate basic value β _L0 is retrieved and
The trailing injection basic value α _T0 for trailing injection is retrieved using a map having the characteristics shown in FIG. 10, and the take-off rate basic value β for trailing injection is made using the map having the characteristics shown in FIG. _T0 is searched. Generally, the direct entry ratio and the take-away ratio depend on the intake air amount Q (flow velocity) and the engine water temperature Tw. Therefore, the characteristics of the direct entry rate and the removal rate with respect to the intake air amount Q and the water temperature Tw are theoretically or experimentally obtained, and a direct entry rate basic value α _L0 , α _T0 and The carry-out rate basic values β _L0 and β _T0 are calculated.

In step # 7, the correction coefficient γ _α for performing the wet correction on the direct entry rate basic values α _L0 and α _T0 is retrieved using the map having the characteristics shown in FIG. The correction coefficient γ _β for performing the wet correction on the take-away rate basic values β _L0 and β _T0 is searched using the map having the characteristics shown in FIG. Generally, the direct entry rate and the removal rate are the wet amount, that is, the fuel pool F ₃
It changes depending on the amount of fuel held in the water or the water temperature. Therefore, the characteristics of the direct entry rate and the take away rate with respect to the wet amount and the water temperature are theoretically or experimentally obtained, and the direct entry rate and the take away rate are corrected using a map created based on such characteristics. (Wet correction).

In step # 8, the fuel distribution ratio R to the leading injection and the trailing injection (hereinafter referred to as the split ratio R) is set according to the engine speed.
Here, the characteristic of the division ratio R with respect to the engine speed is shown in FIG.
It is set like.

In step # 9, the correction coefficient K for correcting the direct entry ratio and the take-away ratio is calculated according to the division ratio R using the map having the characteristics shown in FIG.
The correction coefficient K is a predetermined value of 0 or more and 1 or less. As described above, in the first embodiment, the fuel injection is divided into the leading injection and the trailing injection in the rotation range of about 1000 rpm or more, but in this case, the time intervals of both injections are relatively close to each other. As a result, interference occurs between the two injections. For this reason, the removal of the fuel adhering to the intake passage wall by the leading injection is hindered by the trailing injection, and the removal rate decreases, while the direct injection rate also decreases. Therefore, the direct entry ratio and the carry-out ratio change depending on the presence / absence of division or the magnitude of the division ratio R. Therefore, the characteristics of the direct entry ratio and the take away ratio with respect to the split ratio are theoretically or experimentally obtained, and the direct entry ratio and the take away ratio are corrected according to the split ratio R using a map created based on such characteristics. I am trying to do it.

In step # 10, using the following equations 7 to 10, the leading injection direct injection rate α _L , the leading injection take-away rate β _L , the trailing injection direct injection rate α _T, and the trailing The injection take-away rate β _T is calculated.

[Formula 7] α _L = K ・ α _L0・ γ _α …………………………………………………… Equation 7

[Formula 8] β _L = K ・ β _L0・ γ _β …………………………………………………………

[Formula 9] α _T = K · α _T0 · γ _α …………………………………………………… Formula 9

[Formula 10] β _T = K · β _T0 · γ _β …………………………………………………… Equation 10

In step # 11, according to the following equation 11,
The pulse width τe _{L of the} leading injection is calculated.

In Equation 11] _{τe L = (1-R)} · (τa-β L · τm) / α L .............................. formula 11 step # 12, the following equation 12, the Rideingu injection The final injection pulse width τ end _L is calculated, and the leading injection is performed from the fuel injection valve 15 at a predetermined timing according to the final injection pulse width τ end _L.

[Number 12] τend _L = τe _L + τv ......................................................... formula 12 It should be noted, τv is invalid injection pulse width.

At step # 13, according to the following equation 13,
The pulse width τ e _T of the trailing injection is calculated.

In Equation 13] _{τe T = R · (τa-} β T · τm) / α T .................................... formula 13 step # 14, the following equation 14, the last of the trailing injection The injection pulse width τ end _T is calculated, and the trailing injection is performed from the fuel injection valve 15 at a predetermined timing according to the final injection pulse width τ end _T.

[Number 14] τend _T = τe _T + τv ...................................................... formula 14 It should be noted, τv is invalid injection pulse width.

In step # 15, the wet amount τm is calculated (updated) by the following equation 15.

Τm = (1-α _L ) ・ τe _L + (1-R) ・ (1-β _L ) ・ τm + (1-α _T ) ・ τe _T + R ・ (1-β _T ) ・ τm ...... Equation 15 After this, the process returns to step # 1 and the control is continued.

As described above, according to the first embodiment, the fuel injection from the fuel injection valve 15 is 2 except for the predetermined low speed region.
Since it is divided, the vaporization and atomization of the fuel are promoted, the fuel distribution in the combustion chamber 3 is made uniform, and the combustibility is enhanced. Further, since the direct entry ratio and the carry-out ratio are corrected according to the division ratio R, the presence or absence of division or the division ratio R
Regardless of the size of the fuel, the required amount of fuel is always accurately supplied to the combustion chamber 3, and the air-fuel ratio is maintained at the target air-fuel ratio.

<Second Embodiment> The second embodiment of the present invention will be described below. The hardware configuration of the second embodiment is the first as shown in FIG.
The configuration of the control unit 18 is the same as that of the embodiment, but is as shown in FIG. Further, since the control method of the fuel control is also partly common to the first embodiment, in order to avoid duplication of description, the fuel is controlled according to the flowcharts shown in FIGS. 15 and 16 while appropriately referring to FIGS. Regarding the control method of the control, only the points different from the first embodiment will be described. In the second embodiment, as shown in FIG. 17, fuel injection is performed only once per cycle regardless of the operating state, the fuel injection timing is set according to the operating state, and the continuous fuel injection interval is set. The direct entry rate and the take-away rate are corrected according to T (T ').

In the fuel control of the second embodiment, step # 21 to step # 2 in the flow chart shown in FIG.
5 is the same as step # 1 to step # 5 in the flowchart shown in FIG. 5 in the first embodiment, respectively, and therefore its description is omitted to avoid duplication. Step #
In step 26, the basic direct entry rate α ₀ is searched using a predetermined map, and subsequently in step # 27, the basic carry-out rate β ₀ is searched using a predetermined map. Although not shown, the maps for obtaining the basic direct entry rate α ₀ and the basic take-away rate β ₀ are basically as shown in FIGS. 7 and 8 (first embodiment),
Alternatively, it has characteristics as shown in FIGS. 9 and 10 (first embodiment).

In step # 28, the fuel injection timing (injection timing) is set in accordance with the engine speed N and the air charge amount Ce using a map such as that shown in FIG. In the map shown in FIG. 18, the fuel injection timing is advanced as the engine speed N is high, and the fuel injection timing is advanced as the air charge amount Ce is large.

In step # 29, it is determined whether or not the injection timing has changed. Here, if the injection timing has changed (YES), in step # 30, the injection interval T is calculated using the map having the characteristics shown in FIG.
Direct input rate correction value alpha ₁ is set for, followed by step # 31, after the carry-off ratio correction value beta ₁ is set for the injection interval T using a map having the characteristics shown in FIG. 20, step # 34 is executed. That is, the shorter the injection interval T, the greater the degree of interference between the previous fuel injection and the current fuel injection. Therefore, the removal of the fuel adhering to the intake passage wall in the previous fuel injection is hindered by the current fuel injection, and the removal rate is reduced and the direct injection rate is also reduced. Therefore, as the injection interval T is shorter, the direct entry ratio and the carry-out ratio are corrected to the decreasing side.

On the other hand, if it is determined in step # 29 that the injection timing has not changed (NO), there is no need to correct the direct entry ratio and the carry-out rate, so in step # 32 the direct entry ratio correction value α ₁ Is set to 0, and subsequently, the carry-out rate correction value β ₁ is set to 0 in step # 33, and then step # 34
Is executed.

At step # 34, the final direct entry rate α is set by a normal method based on the basic direct entry rate α ₀ and the direct entry rate correction value α _1, and then at step # 35, the basic take-away rate α is set. The final removal rate β is set based on β ₀ and the removal rate correction value β ₁ . Next, in step # 36, the final injection pulse width is calculated, and then in step # 37
Then, the fuel injection with the final injection pulse width is performed at the injection timing set in step # 28. Then, the process returns to step # 21.

In this way, in the second embodiment,
The direct injection ratio and the carry-out ratio are corrected according to the fuel injection interval, and the required amount of fuel is accurately supplied to the combustion chamber 3 in each cycle.
Is supplied to.

In addition to the first or second embodiment, the direct entry ratio and the carry-out ratio decrease as the time interval between fuel injections becomes shorter, that is, basically when the engine speed is higher. Even if the correction is made to the side, the required amount of fuel can be accurately supplied to the combustion chamber.

[0037]

According to the first aspect of the present invention, the fuel injection can be performed a plurality of times in one cycle according to the operating condition, so that the fuel distribution in the combustion chamber can be made uniform. The flammability of the air-fuel mixture can be improved. Further, in general, when the fuel injection is performed a plurality of times in one cycle, the removal of the fuel adhering to the intake passage in the previous fuel injection to the combustion chamber is hindered by the subsequent fuel injection, and Although the phenomenon that the direct injection amount of fuel injection decreases, according to the present plan, when the fuel injection is performed a plurality of times in one cycle, the direct injection rate estimated value and the carry-out ratio are removed, compared with the case where the fuel injection is performed only once. Since the rate estimation value is corrected to the decreasing side, the accuracy of estimation is increased, and the fuel of the required fuel amount can be accurately supplied to the combustion chamber.

In general, when the interval (crank angle) between the fuel injections is short, the removal of fuel adhering to the intake passage wall due to the previous fuel injection to the combustion chamber is hindered by the current fuel injection, while the direct injection rate is increased. However, according to the second aspect of the invention, the shorter the interval between the previous fuel injection and the current fuel injection, the closer the direct entry rate estimation value and the carry-out rate estimation value are to the decreasing side. Since the correction is performed, the accuracy of the estimation is improved, and the required amount of fuel can always be accurately supplied to the combustion chamber regardless of the fuel injection interval.

Generally, when the time interval between fuel injections is short, that is, when the engine speed is basically high, the fuel adhered to the intake passage wall by the previous fuel injection is taken away to the combustion chamber this time. While it is hindered by fuel injection, the phenomenon that the direct injection rate becomes low occurs,
According to the third aspect of the invention, the shorter the time interval between the previous fuel injection and the current fuel injection, the more the direct entry rate estimated value and the carry-away rate estimated value are corrected to the decreasing side, so the accuracy of the estimation Therefore, regardless of the length of the time interval between the fuel injections, that is, basically, regardless of the engine speed, it is possible to always accurately supply the required amount of fuel to the combustion chamber.

[Brief description of drawings]

FIG. 1 is a block diagram of a fuel control device according to the present invention.

FIG. 2 is a system configuration diagram of an engine including a fuel control device according to the present invention.

FIG. 3 is a diagram schematically showing the behavior of fuel injected from a fuel injection valve of the engine shown in FIG.

FIG. 4 is a diagram showing a characteristic of a division ratio with respect to an engine speed in the first embodiment.

FIG. 5 is a first half of a flowchart showing a control method of fuel control in the first embodiment.

FIG. 6 is a second half of a flowchart showing a control method of fuel control in the first embodiment.

FIG. 7 is a diagram showing a characteristic of a direct injection ratio basic value for leading injection with respect to an intake air amount and a water temperature in the first embodiment.

FIG. 8 is a diagram showing characteristics of a leading injection take-away ratio basic value with respect to an intake air amount and a water temperature in the first embodiment.

FIG. 9 is a diagram showing characteristics of a trailing injection direct injection rate basic value with respect to an intake air amount and a water temperature in the first embodiment.

FIG. 10 is a diagram showing a characteristic of a trailing injection take-away rate basic value with respect to an intake air amount and a water temperature in the first embodiment.

FIG. 11 is a diagram showing the characteristics of the wet amount correction coefficient with respect to the direct entry ratio with respect to the wet amount and the water temperature in the first embodiment.

FIG. 12 is a diagram showing characteristics of a wet amount correction coefficient with respect to a carry-out rate with respect to a wet amount and a water temperature in the first embodiment.

FIG. 13 is a diagram showing a characteristic of a correction coefficient for a direct entry ratio and a carry-out ratio with respect to a division ratio in the first embodiment.

FIG. 14 is a block diagram of another fuel control device according to the present invention.

FIG. 15 is a first half of a flowchart showing a control method of fuel control in the second embodiment.

FIG. 16 is the second half of the flowchart showing the control method of the fuel control in the second embodiment.

FIG. 17 is a diagram showing a fuel injection timing in the second embodiment.

FIG. 18 is an example of a map for setting fuel injection timing in the second embodiment.

FIG. 19 is a diagram showing a characteristic of a direct injection rate correction value with respect to an injection interval in the second embodiment.

FIG. 20 is a diagram showing characteristics of a carry-out rate correction value with respect to an injection interval in the second embodiment.

[Explanation of symbols]

 CE ... Engine 2 ... Intake port 3 ... Combustion chamber 11 ... Intake passage 15 ... Fuel injection valve 18 ... Control unit

Claims (3)

[Claims] 1. A ratio (direct injection ratio) of fuel introduced directly into a combustion chamber of fuel injected from a fuel injection valve in each cycle is estimated, and the proportion of fuel adhering to an intake passage wall is calculated. Estimate the proportion of fuel that is carried away to the combustion chamber in the cycle (takeaway rate), and based on the above direct entry rate and the above takeaway rate, the portion of the fuel injected in the cycle that is directly carried into the combustion chamber. And a fuel injection amount setting means for setting the fuel injection amount such that the total amount of the fuel adhering to the intake passage wall that is carried away to the combustion chamber in the cycle matches the fuel demand amount in the cycle. In the engine fuel control device provided, the fuel injection pattern includes a single injection pattern in which injection is performed only once per cycle and a plurality of injection patterns in which injection is performed multiple times per cycle. And a plurality of injection patterns set by the injection pattern setting means, the direct entry rate estimation value and the carry-out rate estimation value are reduced as compared with the case where a single injection pattern is set. A fuel control device for an engine, characterized in that an estimated value correction means for making a correction is provided on the side. 2. In each cycle, the ratio (direct injection ratio) of the fuel directly introduced into the combustion chamber of the fuel injected from the fuel injection valve is estimated, and the ratio of the fuel adhering to the intake passage wall is calculated. Estimate the proportion of fuel that is carried away to the combustion chamber in the cycle (takeaway rate), and based on the above direct entry rate and the above takeaway rate, the portion of the fuel injected in the cycle that is directly carried into the combustion chamber. And a fuel injection amount setting means for setting the fuel injection amount such that the total amount of the fuel adhering to the intake passage wall that is carried away to the combustion chamber in the cycle matches the fuel demand amount in the cycle. In the engine fuel control device provided, the injection timing setting means for setting the fuel injection timing according to the operating state and the direct injection when the interval between the previous fuel injection and the current fuel injection is shorter Fuel control system for an engine, characterized in that the estimated value correcting means for correcting the estimated value and the carry-off ratio estimated value decrease side. 3. A ratio (direct injection ratio) of fuel brought into the combustion chamber directly in the fuel injected from the fuel injection valve in each cycle is estimated, and the ratio of the fuel adhering to the intake passage wall is calculated. Estimate the proportion of fuel that is carried away to the combustion chamber in the cycle (takeaway rate), and based on the above direct entry rate and the above takeaway rate, the portion of the fuel injected in the cycle that is directly carried into the combustion chamber. And a fuel injection amount setting means for setting the fuel injection amount such that the total amount of the fuel adhering to the intake passage wall that is carried away to the combustion chamber in the cycle matches the fuel demand amount in the cycle. In the engine fuel control device provided, the estimated value correction means for correcting the direct entry rate estimated value and the carry-away rate estimated value to the decreasing side as the time interval between the previous fuel injection and the current fuel injection is shorter. Establishment Fuel control system for an engine, characterized by being.