JP3139824B2 - Engine fuel control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control system for an engine, and more particularly to a fuel control system for an engine for correcting fuel adhering to an intake pipe.

[0002]

2. Description of the Related Art Conventionally, in a fuel control device for an engine, a part of fuel injected from a fuel injection nozzle adheres to an inner wall surface or the like of an intake passage and is directly supplied from the fuel injection nozzle (direct injection). And the amount of vaporized fuel that has adhered (taken away)
In order to prevent a decrease in the accuracy of the air-fuel ratio control due to the sum of the air supply to the fuel chamber, so-called intake pipe attached fuel correction (also referred to as in-mani-wet correction) is performed in accordance with the operating conditions of the vehicle ( For example, Japanese Patent Publication No. 3-59255
No.).

[0003]

In the above-mentioned conventional fuel control apparatus for performing in-mani-wet correction, the direct entry rate and the carry-out rate are set based on the intake air flow rate. Aixture (ai
r mixture), the ratio of direct entry to the total intake fuel amount (direct entry ratio) and the ratio of carry-out (take-off ratio) differ depending on the state of assist air (presence or absence of assist air). There is a problem that a deviation occurs in the air-fuel ratio. In other words, in the conventional in-mani-wet correction, when the amount of assist air increases and atomization of fuel is promoted, the rate at which fuel enters the fuel chamber together with the intake air (ie, the direct entry rate) due to the small fuel grain size is reduced. On the contrary, when the amount of assist air decreases, the correction of the change of the direct entry rate or the carry-out rate against the decrease of the direct entry rate is not performed, so that there is a problem that the setting of the fuel supply amount is not properly performed. . The present invention has been made in view of such a point, and an object of the present invention is to change the degree of atomization of fuel due to a difference in the supply state of assist air, and to change the direct injection rate of fuel, so that wet correction is performed. An object of the present invention is to provide an engine fuel control device that prevents improper operation.

[0004]

According to the present invention, there is provided an operating state detecting means for detecting an operating state of an engine, and an output from the operating state detecting means. Fuel supply amount setting means for setting a fuel supply amount to be supplied to the engine based on the direct injection ratio of the fuel injected from the injector, which is directly sucked into the combustion chamber, at least as an output from the operating state detecting means. A direct-injection-ratio calculating unit that calculates the carry-out ratio based on at least an output from the operating state detecting unit; A fuel correction means for correcting the fuel supply amount based on the direct entry rate and the removal rate calculated by the direct entry rate calculation means and the removal rate calculation means. In the device, Eamikusucha passage
A supply means for supplying assist air for fuel atomization to a fuel injection port near the injector through the indicator
After the intake pressure near the
The difference between the pressure in the tea passage and the pressure near the injector
Air mixing effect is caused by the amount of air
During the intake, the values of the direct entry rate and the carry-out rate are
It is characterized in that a correction means for increasing the pressure as the pressure increases is provided. Further, the supply means supplies the assist air under certain conditions, also, the correcting means, before at the time of supply at the non-supply of the assist air by the supply means
At the time of supply, it is characterized in that the increase of the direct incidence rate is corrected. Then, the correction means is characterized in changing the direct input rate according to the assist air amount.

[0005]

In the above-described configuration, an appropriate wet correction is always performed regardless of the assist air supply state.

[0006]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 2 is a diagram illustrating an overall configuration of an engine fuel control device (hereinafter, referred to as a device) according to an embodiment of the present invention. In FIG.
The piston 2 slides inside the combustion chamber 3 of the combustion chamber 3.
Supports an intake port 4 and an exhaust port 6. An intake valve 7 is provided between the intake port 4 and the combustion chamber 3.
However, an exhaust valve 8 is arranged between the exhaust port 6 and the combustion chamber 3. A throttle valve 9 for controlling the amount of intake air is provided upstream of the intake port 4, and a surge tank 10 as an intake expansion chamber is provided downstream of the throttle valve 9. Further downstream, an injector 11 for injecting and supplying fuel is provided. In addition, the intake port 4
A bypass passage 12 that bypasses the throttle valve 9 and communicates upstream and downstream thereof is provided to supply auxiliary air to the combustion chamber 3. An ISC valve 13 for opening and closing the bypass passage is provided in the middle of the bypass passage 12. An air mixture passage 41 for supplying assist air for atomizing the fuel is provided between the upstream side of the intake port 4 and the vicinity of the fuel injection port of the injector 11. An air mix control valve 42 for controlling the opening and closing of the air mixer is provided.

The amount of air taken into the intake port 4 is detected by an air flow sensor 20a in the air flow meter 20,
The temperature of the intake air is detected by an intake air temperature sensor 21. The throttle opening sensor 23 has a built-in idle switch 22 and detects the opening of the throttle valve 9. The distributor 15 is provided with a rotation speed sensor 25 for detecting the engine rotation speed, the exhaust port 6 is provided with an O ₂ sensor 26, and the downstream side thereof is provided with a catalyst device 24. . Further, the temperature of the cooling water in the water jacket is detected by a water temperature sensor 28. The engine control unit (ECU) 30 receives signals from the above-described sensors, and supplies an ignition time control signal to the distributor 15, a control signal for adjusting the fuel injection amount to the injector 11, and assist air. A control signal is sent to the air mix control valve 42 for supply. Further, a map (to be described later) is stored in a built-in memory (not shown). Next, fuel control in the apparatus of the present embodiment will be described in detail.

<Description of Principle of Wet Correction> In the wet correction, as described above, the fuel directly injected into the combustion chamber from the fuel injected from the injector and the fuel adhering to the wall of the intake passage and then being vaporized. This is a fuel correction for setting the fuel supply amount to the engine based on the amount taken in and taken into the combustion chamber. In this wet correction, the ratio of the direct entry to the carry-in amount varies depending on the amount of fuel adhering to the intake passage wall (wet amount). In setting the carry-out ratio and carry-out ratio (removal ratio β), proper fuel control cannot be realized unless the wet amount is taken into account. That is, the injection amount from the injector is controlled such that the injection amount corresponding to the intake amount matches the actually sucked fuel while taking the direct entry rate and the carry-out rate into consideration. The evaporation of fuel adhering to the intake passage wall is mainly governed by the quality of the contact state with the intake air flow and the passage wall temperature,
When the wet amount itself is small, the contact state with the intake air flow is extremely deteriorated and the evaporation of the attached fuel is impaired, and the injected fuel is also affected by the unevenness of the wall surface due to the small wet amount. , Suction into the combustion chamber is inhibited. As a result, an increase in the amount of wetness and a decrease in the direct entry are caused. When the amount of wetness is large, the contact state between the adhered fuel and the intake air flow is improved, so that the evaporated fuel of the adhered fuel is improved and the suction of the injected fuel into the combustion chamber is promoted, so that the amount of direct injection increases. .

FIG. 3 is a diagram for explaining the wet correction. In the figure, the fuel injected from the injector 11 has an attachment amount F1
And a direct entry F2 that is directly sucked into the combustion chamber 1a. Further, the fuel (wet amount) F3 adhering to the wall surface of the intake passage 4 is vaporized and carried away F4 taken into the combustion chamber 1a, remains as it is without vaporizing, and is vaporized and sucked at the next injection. The remaining fuel is divided into Therefore,
In the case of performing the wet correction in consideration of the carry-out amount F4, the wet amount serving as the basis for the calculation of the carry-out amount is determined by comparing the amount of the fuel previously injected to the amount adhered to the intake passage wall with the amount of the previous adhered amount. Of these, it is necessary to perform the calculation based on the residual fuel that has not been removed in vaporization.

<Explanation of Correction Control of Direct Entry Rate and Removal Rate> FIG. 4 is a flowchart showing a procedure of correction control of the direct entry rate α and the removal rate β of the fuel in the apparatus according to the present embodiment. In step S1 in the figure, data is read from each sensor. Here, as the data, the intake air amount Q, the engine speed Ne, and the cooling water temperature Tw, which are output signals from the air flow meter 20 corresponding to the intake air amount, are read. Then, in step S2, it is determined whether or not the air mixing is being executed based on the flag corresponding to the control state of the air mixing control valve 42. The execution of the airmix is determined by whether or not the operation state of the engine is in the airmix execution region, and is usually performed in a low / medium load region which is an operation region that does not require engine output. Then, when the engine is in an idle state or in a high load region, the execution of the air mix is not performed outside the execution region of the air mix. The reason why the air mixing is not performed in the idle state is that a large amount of air is required to atomize the fuel, and the idle speed is increased. Further, the reason why execution in the high-load region is suspended is that, in this region, if the atomization of the fuel is too good, the intake filling efficiency is reduced due to the vaporization and atomization of the fuel, and as a result, the engine output is reduced. The reason is that it is better not to promote the vaporization of fuel where power is required.

If it is determined in step S2 that the air mixing is not being performed, then in step S3, based on the intake air amount Q and the engine speed Ne, the filling amount passing through the air flow meter is calculated by the following equation (1). Calculate Ceo and calculate equation (2)
, The intake charging amount Ce of the cylinder is obtained. Ceo = Ka · Q / Ne (1) where Ka is a constant. Ce = Kc · Ce + (1−Kc) · Ceo (2) where Kc is a constant (0 ≦ Kc <1). Then, in step S4, the amount of change of the intake air charge is calculated. That is, the intake air charge obtained in step S3 in the previous process is Ce _i−1 , and the air intake charge obtained in the current process is Ce _i
When _i, temporal variation DCe of intake air charging amount can be obtained by _{DCe = Ce i-1 -Ce i} ... (3). In step S5, based on the intake charging amount Ce of the cylinder, the intake air flow rate Qcyl at the mounting portion of the injector 11 is calculated according to the following equation: Qcyl = (Ce · Ne) / Ka (4) Further, in step S6, the variation DCe the intake charge, even when Eamikusu is not running, compares the magnitude of the KCe _AM is a determination value when the Eamikusu effects by changes in the intake charge Ce occurs. Then, when it is determined in step S6 that the amount of change in intake air charge amount DCe ≦ the determination value KCe _AM , the direct entry rate α and the carry-out rate β are corrected in subsequent steps.

That is, in the present embodiment, the correction of the direct entry rate and the carry-out rate in the transition period from the execution of the air mixing to the non-execution thereof is performed. Therefore, step S
In S7 and S8, A correction for α and β correction shown in FIG.
The α and β correction amounts corresponding to the change amount DCe of the intake air charge obtained in step S4 are searched from the map indicating the B correction characteristics. That is, in step S7, performs A correction by f ₁ characteristic of FIG. 5 (a value after the correction and alpha _HOSEI),
In step S8, perform B correction by f ₂ characteristic of FIG. 5 _(HOSEI values corrected beta). These corrections are performed when the air mixing control valve 42 is in the closed state and the air mixing is not being performed, even when the air mixing control valve 42 is in the closed state, the direct entry rate when there is an air mixing effect due to the residual air corresponding to the volume of the air mixing passage 41,
This is a correction that approaches the carry-out rate, as shown in FIG.
There is such a characteristic that the larger the change amount DCe of the intake air, the larger the correction amount of the direct entry rate and the removal rate becomes. In other words, if there is residual air in the air mixture passage,
Even if the air-mix control valve 42 is closed, the residual air acts on atomization of the fuel, so that correction is necessary.

Here, the reason why the inflow state of the assist air can be detected from the change amount DCe of the intake air will be briefly described. When the throttle opening is constant, the intake port 4
Since there is no difference between the pressure in the vicinity of the injector 11 and the pressure in the air mixture passage 41, there is no air flow in the injector 11 portion. However, when the throttle opening changes, the pressure in the surge tank 10 and the pressure in the vicinity of the injector 11 change in the same tendency as the change in the intake and charging amount Ce of the cylinder, while the pressure in the air mixture passage 41 increases. The pressure in the surge tank 10 and the pressure in the vicinity of the injector 11 change with the influence of the throttle in the portion 11. Therefore, an air mixing effect is generated by the amount of air corresponding to the difference between the pressure in the air mixture passage 41 and the pressure in the vicinity of the injector 11, so that a change in the output of the air flow sensor 20a, that is, a change in the change amount DCe of the intake air, is determined. With the time delay, the inflow state of the assist air is detected. Next, in steps S9 and S10, final calculations of the direct entry rate α and the carry-out rate β are performed. That is, in step S9, the direct entry ratio α _BASE when there is no assist air for the intake air flow rate Qcyl obtained in step S5 is read from the characteristic diagram shown in FIG. 6, and the assist air amount is calculated from the characteristic diagram shown in FIG. _Reads the direct _entry rate α _AIRM when there is assist air according to the size. And
The final direct incidence rate α is calculated according to the following equation (5).

Α = α _BASE · α _HOSEI + α _AIRM · (1−α _HOSEI ) (5) In step S10, there is no assist air for the intake flow rate Qcyl obtained in step S5 from the characteristic diagram shown in FIG. load the carry-off ratio beta _BASE when, further, the characteristic diagram shown in FIG. 9, reads the carry-off ratio beta _AIRM when there is the assist air in accordance with the magnitude of the assist air amount. Then, the final carry-out rate β is calculated according to the following equation (6). That is, β = β _BASE · β _HOSEI + β _AIRM · (1−β _HOSEI ) (6) The processing in steps S9 and S10 is to reduce the degree of reflection of the direct entry rate or the carry-out rate without airmix to the final direct entry rate α or carry-out rate β, and to reduce the direct entry rate with air mix. This means that the direct entry rate α and the carry-out rate β are averaged by increasing the degree of reflection of the rate or the carry-out rate.

<Calculation of wet correction amount and injection pulse width
> Using the direct entry rate α and carry-out rate β obtained in the above processing
The calculation of the wet correction amount will be described. Immaniu
Et amount τm_i Is the effective pulse width obtained in the previous process
(Wet-corrected injection pulse width) is τe_i-1 , Last time
Τm_i-1 Τm_i = (1-α) · τe_i-1 + (1-β) · τm_i-1 ... (7) can be expressed. It is also drawn directly into the combustion chamber
Fuel amount τcyl_i Is τcyl_i = Α ・ τe_i + Β · τm_i ... (8) The amount of fuel τcyl directly drawn into the combustion chamber_i 
And basic injection pulse width τa _i i Are equal, the optimal wafer
In this case, τcy is calculated in the above equation (8).
l_i = Τa_i Then, τa_i = Α ・ τe_i + Β · τm_i ... (9) Therefore, from the above equation (9), the effective injection pulse
Width, that is, wet correction injection amount τe_i Is τe_i = ｛Τa_i −β ・ τm_i ｝ / Α (10)

Next, from the map shown in FIG. 10, a warming-air increasing rate Cw corresponding to the cooling water temperature Tw is obtained, and the cylinder suction filling amount Ce and the warming-air increasing rate C obtained by the above equation (2).
The basic injection pulse width τa is calculated using w. τa = KP · Cw · Ce (11) where KP is a constant. Then, from the map shown in FIG. 11, the invalid injection pulse width corresponding to the battery voltage V _B τv
Read. This is to compensate for a delay in response of fuel injection by the injector to a control signal for fuel injection. Then, the final injection pulse width Te is calculated by the following equation (12).
Ask for. Te = τa + τv (12) As described above, the fuel corresponding to the final injection pulse width Te is injected from the injector 11. As described above, according to the present embodiment, the difference in the state of the air mixture by the assist air changes the direct entry rate and the removal rate of the fuel entering the combustion chamber, thereby changing the degree of atomization of the fuel by the air mixture. There is an effect that the fuel supply amount can be appropriately set even if the direct entry rate and the carry-out rate change.

[0017]

As described above, according to the present invention,
Correcting the direct entry rate and the carry-out rate according to the supply state of the assist air has an effect that the fuel supply amount can be appropriately set regardless of the degree of atomization of the fuel.

[Brief description of the drawings]

FIG. 1 is a basic conceptual diagram of the present invention,

FIG. 2 is a diagram showing an overall configuration of an engine fuel control device according to an embodiment of the present invention;

FIG. 3 is a diagram for explaining wet correction;

FIG. 4 is a flowchart showing a procedure of correction control of a fuel direct entry rate α and a carry-out rate β in the apparatus according to the embodiment;

FIG. 5 is a map showing A correction and B correction characteristics for α and β correction,

FIG. 6 is a map showing characteristics of a direct entry rate α _BASE when there is no assist air;

FIG. 7 is a map showing characteristics of a carry-out rate β _BASE when there is no assist air,

FIG. 8 is a map showing characteristics of a direct _entry rate α _AIRM when assist air is present according to the amount of assist air,

FIG. 9 is a map showing the characteristics of the carry-out rate β _AIRM when there is assist air according to the amount of assist air,

FIG. 10 is a map of a fuel injection amount warm-up rate,

FIG. 11 is a map showing an invalid injection time of an injector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine main body 2 Piston 3 Combustion chamber 4 Intake port 6 Exhaust port 7 Intake valve 8 Exhaust valve 9 Throttle valve 10 Surge tank 11 Injector 12 Bypass passage 13 ISC valve 15 Distributor 20 Air flow meter 20a Air flow sensor 21 Intake temperature sensor 22 Idle switch 23 Throttle opening sensor 25 Rotation speed sensor 26 O ₂ sensor 28 Water temperature sensor 30 Engine control unit (ECU) 41 Amicture passage 42 Amics control valve

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-23339 (JP, A) JP-A-62-159749 (JP, A) JP-A-4-54240 (JP, A) JP-A-2- 112667 (JP, A) JP-A-5-118241 (JP, A) JP-B-3-59255 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/04 330

Claims (3)

(57) [Claims] 1. An operating state detecting means for detecting an operating state of an engine, a fuel supply amount setting means for setting an amount of fuel supplied to the engine based on an output from the operating state detecting means, and an injection from an injector. Of the fuel
A direct entry rate calculating means for calculating a direct entry rate drawn directly into the combustion chamber based on at least an output from the operating state detecting means; and a carry-out rate at which fuel adhering to the intake passage is vaporized and drawn into the combustion chamber. The carry-out rate calculating means that is calculated based on at least the output from the operating state detecting means, and the direct supply rate and the carry-out rate calculated by the direct-incoming rate calculating means and the carry-out rate calculating means, and the fuel supply amount is used. A fuel correcting device for correcting the fuel, wherein a supply device for supplying assist air for atomizing fuel to a vicinity of a fuel injection port of the injector via an air mixture passage; and an intake pressure near the injector. After the change
The pressure in the aiming passage and the vicinity of the injector
Air mixture effect due to volume of air corresponding to pressure difference
While occurs, the direct input rate and the value of the carry-off ratio as the intake pressure is high, the fuel control system for an engine characterized in that it comprises a correcting means for increasing correction. Wherein said supplying means supplies the assist air under certain conditions, also, the correcting means, when the supply at the time of supply at the non-supply of the assist air by the supply means
A fuel control system for an engine according to claim 1, characterized by performing the increase correction of the direct input rate. Wherein said correction means, fuel control system for an engine according to claim 1, characterized in that changing the direct input rate according to the assist air amount.