JPH05296081A - Fuel control device for engine - Google Patents

Abstract

PURPOSE:To prevent discrepancy of air-fuel ratio due to disagreement between actual and set amounts of direct suction by setting a direct suction rate in accordance with an injection speed in a region of the injection speed of fuel faster than an intake speed, in the case of setting the direct suction rate of directly sucking fuel into a combustion chamber. CONSTITUTION:Based on an operating condition of an engine detected by an operative condition detecting means, a fuel amount supplied to the engine is set in a fuel supply amount setting means. A direct suction rate of directly sucking fuel into a combustion chamber is set by a direct suction rate setting means. Further, a take away rate of vaporizing fuel, adhering to an internal wall of an intake passage, absorbed to the combustion chamber is set by a take away rate setting means. The fuel supply amount is corrected by a correcting means in accordance with the direct suction rate and the take away rate of fuel. In the above device, the direct suction rate is set in accordance with an injection speed of fuel injected from an injector. That is, in a region of the fuel injection speed faster than an intake speed, the direct suction rate of fuel is set in accordance with the injection speed, to always perform adequate wet correction.

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 intake pipe adhering fuel.

[0002]

2. Description of the Related Art Conventionally, in a fuel control system for an engine, a part of fuel injected from a fuel injection nozzle adheres to an inner wall surface of an intake passage or the like and is directly supplied (a direct injection amount) from the fuel injection nozzle. Evaporated portion of fuel that adheres to (take away portion)
In order to prevent the deterioration of the accuracy of the air-fuel ratio control due to the sum of the above being supplied to the fuel chamber, so-called intake pipe adhering fuel correction (also called in-maniwet correction) is performed according to the operating conditions of the vehicle ( For example, Japanese Patent Publication No. 3-59255
Publication).

[0003]

However, in the above-described conventional fuel control system for performing in-maniwet correction, the direct entry ratio and the carry-out ratio are set based on the intake flow rate, but the engine speed is low and the intake flow rate is low. There are situations where it is lower than the fuel injection speed. In such cases, direct entry rate,
Since the carry-out rate depends on the fuel injection speed rather than the intake air flow rate, the fuel injection speed from the injector is almost constant even if the intake air flow speed in the intake pipe varies depending on the engine speed. There is a problem that the air-fuel ratio is deviated due to the difference in the ratio of direct input to the amount (direct input ratio) and the ratio of direct carry-out (take-away ratio). Further, even when the fuel supply is cut off, the amount of fuel adhering to the wall surface is different from the normal amount, so that there is a problem that the direct entry ratio and the carry-out ratio change when the supply is restored. The present invention has been made in view of the above points, and an object of the present invention is to set a direct injection amount set as an actual direct injection amount in a region in which a direct injection amount of fuel from an injector is controlled by a fuel injection speed rather than an intake flow velocity. An object of the present invention is to provide a fuel control device for an engine, which prevents deviation of the air-fuel ratio due to the fact that the minutes do not match.

[0004]

In order to achieve the above object, the present invention comprises the following constitutions. That is, the operating state detecting means for detecting the operating state of the engine, the fuel supply amount setting means for receiving the output of the operating state detecting means and setting the fuel supply amount to be supplied to the engine, and the fuel injected from the injector. Among these, the direct injection rate setting means for setting the direct injection rate directly absorbed in the combustion chamber based on at least the parameter related to the intake flow velocity, and the removal rate in which the fuel adhering to the inner wall of the intake passage is vaporized and absorbed in the combustion chamber. Is set based on at least a parameter related to the intake flow velocity, and the fuel supply amount is corrected by the direct entry rate and the away rate set by the direct entry rate setting means and the away rate setting means. In the engine fuel control device including the correction means, the direct injection ratio is set based on the fuel injection speed from the injector. Preferably, when the intake flow velocity is higher than the fuel injection speed, the direct injection ratio is set based on the intake flow velocity, and when the fuel injection speed is higher than the intake flow velocity, the direct injection ratio is set based on the fuel injection velocity. Further, preferably, in a region where the intake flow velocity is slower than the fuel injection speed, setting of the direct injection rate based on the intake flow velocity is limited.

[0005]

With the above construction, the function of always performing an appropriate wet correction is achieved regardless of the operating state of the engine.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 2 is a diagram showing an overall configuration of an engine fuel control apparatus (hereinafter referred to as an apparatus) according to an embodiment of the present invention. In the figure, the engine body 1
The piston 2 slides in the combustion chamber 3 of the
An intake port 4 and an exhaust port 6 are supported by. An intake valve 7 is provided between the intake port 4 and the combustion chamber 3.
However, exhaust valves 8 are provided between the exhaust port 6 and the combustion chamber 3, respectively.

A throttle valve 9 for controlling the intake air amount is provided on the upstream side of the intake port 4, and a surge tank 10 as an intake expansion chamber is provided on the downstream side thereof. Further downstream thereof, an injector 11 for injecting and supplying fuel
Is provided. The intake air amount to the intake port 4 is detected by the air flow sensor 20a in the air flow meter 20, and the intake air temperature is detected by the intake temperature sensor 21. The throttle opening sensor 23 is an idle switch 22.
Is built in and detects the opening degree of the throttle valve 9. Further, 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 catalyst device 24 is provided downstream thereof.
Are arranged. Further, the temperature of the cooling water in the water jacket is detected by the water temperature sensor 28.

The engine control unit (ECU) 30 is
In addition to receiving signals from the above-mentioned sensors, it sends an ignition time control signal to the distributor 15 and sends a control signal to the injector 11 for adjusting the fuel injection amount. Further, a map (described later) is stored in a built-in memory (not shown). Next, fuel control in the apparatus of this embodiment will be described in detail.

<Description of Wet Correction> Wet correction is
Among the fuel injected from the injector as described above, the engine is based on the directly-introduced amount that is directly sucked into the combustion chamber and the carry-off amount that is adhered to the intake passage wall and then vaporized and sucked into the combustion chamber. It is a fuel correction for setting the fuel supply amount to the. In this wet correction, since the ratio of the direct entry amount and the carry-out amount fluctuates depending on the amount of adhered fuel (wet amount) adhering to the intake passage wall, the ratio of the direct entry amount to the total intake fuel amount (the direct entry ratio α and Yes) and the carry-out ratio (take-away ratio β) are set, proper fuel control cannot be realized unless the wet amount is taken into consideration. That is, the injection amount from the injector is controlled so that the injection amount commensurate with the intake air amount and the fuel actually sucked in match with each other while considering the direct injection ratio and the carry-out ratio. The evaporation of the fuel adhering to the intake passage wall is governed mainly by the quality of the contact state with the intake flow and the temperature of the passage wall, and when the weight itself is small, the contact state with the intake flow becomes extremely poor. As a result, the evaporated fuel is impaired in vaporizability, and the injected fuel is also influenced by the unevenness of the wall surface due to the small amount of weight, so that the intake into the combustion chamber is hindered. As a result, the amount of wet increases and the amount of direct insertion decreases. Further, when the amount of wet is large, the contact state between the adhered fuel and the intake air flow is good, so that the vaporization property of the adhered fuel is improved and the intake of the injected fuel into the combustion chamber is promoted, and the direct injection amount is increased. ..

FIG. 3 is a diagram for explaining this weight correction. In the figure, the fuel injected from the injector 11 has a deposit F1 attached to the wall surface of the intake passage 4.
And a directly-inserted portion F2 that is directly sucked into the combustion chamber 1a. Further, the fuel (wet amount) F3 attached to the wall surface of the intake passage 4 is vaporized and carried away into the combustion chamber 1a, and the carry-out portion F4 remains without being vaporized and is vaporized and sucked at the next injection. It is divided into the residual fuel amount to be used. Therefore,
When the weight correction is performed in consideration of the carry-out amount F4, the weight amount that is the basis of the calculation of the carry-out amount is calculated by calculating the amount of the previously injected fuel that has adhered to the intake passage wall and the amount that has previously adhered. Among them, in vaporization, it is necessary to perform calculation based on the residual fuel amount that was not taken away.

<Description of Fuel Injection Control> FIGS. 4 and 5 are flow charts showing the procedure of fuel injection control in the apparatus according to the present embodiment. In step S1 of FIG. 4, data is read from each sensor. Here, 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 in as data. Then, in step S2, based on the intake air amount Q and the engine speed Ne, the filling efficiency Ceo of passing through the air flow meter is calculated by the following formula (1), and the cylinder suction filling is performed according to the formula (2). Efficiency C
Find e. Ceo = Ka · Q / Ne (1) where Ka is a constant. Ce = Kc · Ce + (1-Kc) · Ceo (2) However, Kc is a constant (0 ≦ Kc <1). Step S
In No. 3, based on the above-mentioned intake and charging efficiency Ce of the cylinder,
The intake air flow velocity Qcyl at the attachment site of the injector 11 is calculated according to the equation Qcyl = (Ce · Ne) / Ka (3). Then, in step S4, the velocity Vf at which the fuel is injected from the injector 11 and the intake flow velocity Qcyl are compared.

That is, at step S4, the intake flow velocity Qc
If it is determined that yl> fuel injection speed Vf, step S
At 5, the direct injection rate α is set based on the intake flow velocity Qcyl. If the intake air flow rate Qcyl <fuel injection speed Vf, the process proceeds to step S6 and the direct injection rate α based on the fuel injection speed
Set. The fuel injection speed Vf has a constant value determined by the injection opening area of the injector 11 and the fuel injection pressure. Therefore, when the engine speed Ne is higher than a predetermined value and the intake air flow rate Qcyl> the fuel injection speed Vf, the engine cooling water temperature Tw and the engine speed Ne shown in FIG. , A direct injection rate based on the intake flow velocity Qcyl is set. On the other hand, the engine speed Ne is lower than the predetermined value, and the intake flow velocity Qcyl
<If the fuel injection speed Vf (for example, when the fuel injection speed is 15 m / sec and the engine speed is less than 1500 rpm, the intake flow velocity becomes slower than the fuel injection speed), the map of FIG. 6 is changed to the fuel injection speed Vf. Based on this, the direct entry rate α is set.

That is, as the engine speed decreases, the intake flow velocity decreases, and the fuel directly drawn into the combustion chamber is governed by the injection speed, so the direct injection rate α also decreases.
The map shown in FIG. 6 has a characteristic in which the value of the direct injection rate α is corrected at a low engine speed. Further, in step S7, the take-away rate β with the engine cooling water temperature Tw and the engine speed Ne as parameters is retrieved from the map shown in FIG. Then, in step S8 in FIG. 5, correction is made for α and β obtained in the above processing. That is, from the map shown in FIG. 8, the correction value K _3A corresponding to the fuel injection timing with respect to α obtained in step S5 or step S6 is read, and the correction value K _3A is multiplied by α to correct the direct injection rate α. To do. Similarly, the carry-out rate β is corrected by reading the correction value K _3B corresponding to the fuel injection timing from the map shown in FIG. 9 and multiplying the correction value K _3B by β.

The above correction value K_3AAs shown in FIG.
The later the injection timing, the larger the value, and
Positive value K_3BAs is clear from FIG. 9, the injection timing is late.
It is set so that it becomes smaller. This is a burn
The fuel injection timing is set at the beginning of the intake cycle,
The later the timing, the larger the intake valve opening.
A large amount of fuel is directly supplied from the injector to the combustion chamber.
As a result, the amount of fuel adhering to the inner wall surface of the intake passage decreases.
This is to cope with the small number. Direct entry rate α,
If the carry-out rate β is used, the amount of intake manifold τm_i 
Is the effective pulse width (wet correction
Injection pulse width)_{i- 1} , The previous process
Τm_i-1 , Then τm_i = (1-α) · τe_i-1 + (1-β) ・ τm_i-1 … (4). In addition, the amount of fuel τcyl drawn directly into the combustion chamber
_i Is τcyl_i = Α ・ τe_i + Β ・ τm_i … (5) Amount of fuel τcyl drawn directly into this combustion chamber_i 
And basic injection pulse width τa _i i When the
Correction is performed, τcy in the above equation (5)
l_i = Τa_i Then, τa_i = Α ・ τe_i + Β ・ τm_i … (6). Therefore, from the above equation (6), the effective injection pulse
Width, that is, wet correction injection amount τe_i Is τe_i = {Τa_i -Β / τm_i } / Α becomes (7).

In step S9, the warm air increase rate Cw corresponding to the cooling water temperature Tw is obtained from the map shown in FIG. 10, and in the next step S10, the cylinder suction filling efficiency Ce obtained by the above equation (2), Then, the basic injection pulse width τa is calculated using the warm air increase rate Cw. τa = KP · Cw · Ce (8) where KP is a constant. In step S11, which is shown in FIG.
The invalid injection pulse width τv corresponding to the battery voltage V _B is read from the map shown in FIG. This is to compensate for the response delay of the fuel injection by the injector with respect to the fuel injection control signal. Then, in step S12, the final injection pulse width Te is calculated by the following equation (9). Te = τa + τv (9) As described above, the fuel corresponding to the final injection pulse width Te is injected from the injector 11.

As described above, according to this embodiment,
Among the fuel injected from the injector, the direct injection amount directly sucked into the combustion chamber is set in the low engine rotation region where the direct injection amount is controlled by the fuel injection speed rather than the intake air flow rate. In the region where the direct flow rate is governed by the intake flow rate, the direct flow rate is set based on the intake flow rate to correspond the actual direct flow rate to the set direct flow rate, and to obtain an appropriate wet condition that does not depend on the engine speed. There is an effect that the correction can always be performed. Although the setting of the direct injection ratio is changed depending on the engine speed in the above embodiment,
It may be determined whether or not the fuel is being cut, and the setting of the direct injection ratio may be changed according to the state to optimize the wet correction when the supply is restored.

[0017]

As described above, according to the present invention,
In a region where the fuel injection speed is faster than the intake speed, there is an effect that an appropriate wet correction can always be performed by setting the fuel direct injection rate based on the injection speed.

[Brief description of 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 weight correction,

FIG. 4 is a flowchart showing a fuel control processing procedure according to the present embodiment,

FIG. 5 is a flowchart showing a fuel control processing procedure according to the present embodiment,

FIG. 6 is a map showing the characteristics of the fuel direct injection rate α,

FIG. 7 is a map showing the characteristics of fuel removal rate β,

FIG. 8 is a correction value map for the direct injection rate according to the injection timing,

FIG. 9 is a correction value map according to the injection timing for the take-away rate,

FIG. 10 is a map of the warm air increase rate of the fuel injection amount,

FIG. 11 is a map showing ineffective injection time of the injector.

[Explanation of symbols]

1 engine 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 15 distributor 20 air flow meter 20a air flow sensor 21 intake air temperature sensor 22 idle switch 23 throttle opening sensor 25 rotation Number sensor 26 O ₂ sensor 28 Water temperature sensor 30 Engine control unit (ECU)

Claims (4)

[Claims] 1. An operating state detecting means for detecting an operating state of the engine, a fuel supply amount setting means for receiving an output of the operating state detecting means and setting a fuel supply amount to be supplied to the engine, and an injector for injecting the fuel. Out of the fuel, the direct injection rate setting means for setting the direct injection rate directly absorbed in the combustion chamber based on at least the parameter related to the intake flow velocity, and the fuel adhering to the inner wall of the intake passage is vaporized and absorbed in the combustion chamber. A carry-out rate setting means for setting the carry-out rate based on at least a parameter related to the intake flow velocity, and the fuel supply amount based on the direct-insertion rate and the carry-out rate set by the direct-entry rate setting means and the take-away rate setting means. In a fuel control device for an engine, which is provided with a correction means for correcting the above, the direct injection ratio is set based on the injection speed of the fuel from the injector. Fuel control system of the engine. 2. A direct injection rate is set based on the intake flow rate when the intake flow rate is higher than the fuel injection rate, and a direct injection rate is set based on the fuel injection rate when the fuel injection rate is higher than the intake flow rate. The fuel control apparatus for the engine according to claim 1, wherein: 3. The fuel control device for an engine according to claim 1, wherein the setting of the direct injection rate based on the intake flow velocity is limited in a region where the intake flow velocity is slower than the fuel injection velocity. 4. The fuel control device for an engine according to claim 2, wherein the magnitude of the intake flow velocity and the fuel injection velocity is determined based on the engine speed.