JP2508188Y2 - Engine fuel control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a fuel control device for an engine.

(Prior Art) Generally, in an automobile engine, a bypass passage for bypassing a throttle valve is provided in an intake passage thereof, and a control valve for adjusting an opening area of the passage is provided in the bypass passage to adjust an opening degree of the control valve. By adjusting the intake air amount, the idle speed of the engine is made to converge to the target speed.

Furthermore, paying attention to the function of this control valve, after no load racing (that is, idling operation), when the accelerator is rapidly returned and the engine shifts to deceleration operation, the control valve is opened by a predetermined amount After increasing the amount, by decreasing the amount of increase to zero at a predetermined damping rate, it is possible to prevent the engine speed from declining or stalling due to a sudden decrease in the intake air amount during deceleration transition. The so-called dashpot correction control is known (for example, Japanese Patent Publication No. 61
-See the back of No. 15260).

On the other hand, at the time of deceleration of the engine, so-called fuel cut control for temporarily cutting off the fuel supply to the engine is performed for the purpose of improving exhaust emission or improving fuel economy, but this fuel cut control is not limited to when the vehicle is running. It is also performed during deceleration after load racing.

However, in the dashpot correction control and the fuel cut control, the former acts to increase the engine speed, whereas the latter acts to decrease the engine speed. It is not a good idea to do both simultaneously.

For this reason, generally, as shown in FIG. 7, generally, during deceleration, the dashpot correction is prioritized over the fuel cut, and the fuel cut is not performed until the correction amount of the dashpot correction started at the time of deceleration transition becomes zero. This is performed to prevent the engine speed from falling during deceleration and improve exhaust emissions.

(Problems to be solved by the invention) By the way, in the case where the dashpot correction control and the fuel cut control are performed in this way, the dashpot correction control is prioritized over the fuel cut control and waits for the end of the dashpot correction control. When the fuel cut is executed, the fuel is continuously supplied during the decay period of the dashpot correction amount (the period shown by t in FIG. 7) even though the deceleration operation is being performed (the first period). In the hatched area in FIG. 7), a drop in the engine speed due to a sudden decrease in the intake air amount is suppressed.

However, when the dashpot correction control is uniformly prioritized over the fuel cut control during deceleration regardless of the operating condition of the engine, for example, when the engine decelerates from the high speed range like deceleration after no-load racing. Therefore, even in a region where there is almost no problem of engine stall due to a drop in engine speed (in other words, a region in which there is little need for dashpot correction), during deceleration from low speed (that is, a drop in rotation is a concern. Similar to the operation state), the dashpot correction is prioritized over the fuel cut, and the afterburn phenomenon occurs due to the surplus fuel supplied during the dashpot decay period.

Therefore, the present invention is a fuel control for an engine that performs both dashpot correction control and fuel cut control so that both engine stalling resistance at low speed and afterburn prevention at high speed can be achieved. The purpose is to provide a device.

(Means for Solving the Problem) In the present invention, as a concrete means for solving such a problem, a fuel cut means for performing a fuel cut in a region equal to or higher than a first set rotational speed preset at the time of engine deceleration, In an engine equipped with a dashpot air supply means for increasing the intake air amount by a predetermined amount during deceleration and reducing the increase amount with a predetermined attenuation rate, a rotation speed detecting means for detecting an engine speed and the rotation speed detecting means. When the engine speed detected by the engine speed is higher than the second set speed set higher than the first set speed, the fuel cut is performed regardless of whether or not the dashpot air is supplied by the dashpot air supply means. While executing immediately, when the engine speed is lower than the second set speed and when the dashpot air is below a predetermined amount Fuel cut control means for executing fuel cut at this point.

(Operation) Since the present invention has such a configuration, the dashpot air flow at high speed, which is considered to cause a slight decrease in engine speed due to fuel cut because the rotation speed is relatively high even during deceleration, Regardless of the supply of fuel, the fuel cut is executed immediately after the deceleration shift, and the dashpot air is supplied to reduce the engine speed at low speed where the engine speed may drop significantly and engine stall may occur. After the suppression, the fuel cut will be executed.

Therefore, according to the engine fuel control device of the present invention,
At high speed, fuel cut is executed at the same time as deceleration shift, so afterburn is reliably prevented from occurring due to oversupply of fuel during the dashpot correction decay period, and at low speed, dashpot Since the fuel cut is executed at the time when the air is attenuated to a predetermined amount, a practical effect is obtained in which the engine speed is not significantly decreased due to the fuel cut and the engine stall is prevented.

(Embodiment) A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an automobile engine 1 equipped with the fuel control device of the present invention. In FIG. 1, reference numeral 2 is an intake passage, and 3 is an exhaust passage.

The intake passage 2 is provided with an air flow meter 4 from its upstream side.
The throttle valve 5 and the injector 6 are sequentially arranged. Further, a bypass passage 7 that bypasses the throttle valve 5 is formed at a position corresponding to the throttle valve 5 in the intake passage 2, and a control valve 8 that makes the passage area variable is formed in the bypass passage 7. It is provided. In the figure, reference numeral 9 is an ignition plug.

The engine 1 having such a configuration includes the control unit 10
The operation is controlled by. That is, the control unit 10 receives the intake air amount signal, the throttle opening signal, the engine speed signal, the neutral signal and the like, and controls the fuel and the speed of the engine 1. Among these controls, the feedback control of the idle speed using the control valve 8 is a well-known control, and therefore the description thereof is omitted here, and the control valve 8 at the time of deceleration, which is the gist of the present invention, is omitted here. The dashpot correction control and the fuel cut control using the above will be described while interrelating with each other.

First, the basic idea of dashpot correction control and fuel cut control by this control unit will be described with reference to FIGS.
This will be described with reference to the time chart in the figure.

Basically, three control modes to be described later are considered, but as a premise thereof, as shown in FIGS. 2 to 4, the engine speed as a control reference is used as a fuel cut determination reference. The fuel cut speed (corresponding to the first set speed in the scope of utility model registration claims and represented by Ncut ₂ ) and the fuel cut speed higher than the fuel cut speed are set to the dashpot correction. The dashpot determination rotational speed (corresponding to the second set rotational speed in the scope of utility model registration claims and represented by Ncut ₁ ) is set as the execution determination standard.

Further, as a control system for the dashpot correction, so-called standby system control is adopted, and as shown in FIGS. 2 to 4, when the engine shifts from the idle state to the acceleration state (in the case of this embodiment, Is idle switch ON → OFF
The calculation of the correction amount is started from the time when the change is made to), and when the speed changes to deceleration (the idle switch turns from OFF to ON).
The correction amount at the time of changing to (1) is set as the initial value of the GDP dashpot correction, and this correction amount GDP is reduced by a predetermined attenuation rate.

Under such a premise, as a first control mode, as shown in FIG. 2, the control is performed when the engine speed is decelerated from the rotation speed higher than the dashpot determination rotation speed Ncut ₁ . In this case, the dashpot correction is prohibited because it is a driving state in which there is almost no need for the dashpot correction to prevent the engine rotation from falling.
Although the dashpot air is not supplied, the correction amount is calculated), and the fuel cut is executed immediately after the deceleration transition. As a result, the occurrence of afterburn during deceleration is prevented as much as possible.

As a second control mode, in the first control mode, the engine speed during deceleration is the fuel cut speed Ncut ₂
The transmission is driven from the neutral N to the drive D at a higher rotation speed side (that is, a state where the fuel cut is continued).
This is the control in the case where the engine is shifted to a load and the load is applied to the engine. In this case, as shown in FIG. 3, the fuel cut is stopped and the fuel supply is started (fuel return) at the same time when the traveling load is applied. As a result, the engine rotation can be prevented from falling and the engine stall can be reliably prevented.

As a third control mode, as shown in FIG. 4, it is a control when the engine is decelerated from a lower rotation position than the dashpot determination rotation speed Ncut ₁ , and in this case, from the viewpoint of engine stall prevention, The fuel cut is executed after the dashpot correction is executed at the same time as the deceleration transition to suppress the drop of the engine rotation, which is the same as the conventional general control.

By properly using these three control modes according to the operating state of the engine, prevention of afterburn during deceleration from high rotation and engine stall during deceleration from low rotation are both achieved.

Next, the actual operation of the above control will be described based on the flowcharts of FIGS. 5 and 6.

Fuel Control First, the fuel control will be described with reference to FIG. 5. After starting the control, various signals such as the intake air amount and the engine speed are read (step S1).

Next, in step S2, it is determined whether or not the throttle valve is currently fully closed. If the throttle valve is not fully closed, that is, if the vehicle is in an acceleration state, the fuel injection amount according to the current operating state is determined.
Ti is calculated (step S10), and this fuel injection amount Ti is output to the injector (step S6).

On the other hand, when the throttle is fully closed, it is determined in step S3 whether or not it is currently in the neutral state. If the result of determination is that it is in the neutral state, the current rotational speed N is compared with the dashpot determination rotational speed Ncut ₁ in step S4.

Here, when N> Ncut ₁ (that is, in the first control mode), the fuel cut is immediately executed regardless of the presence or absence of the dashpot correction amount (steps S5 and S6).

On the other hand, when N <Ncut ₁ ,
At step S8, the current rotational speed N and the fuel cut rotational speed
Compare with Ncut ₂ . When N> Ncut ₂ (that is, in the third control mode), fuel supply is continued while the dashpot correction amount GDP remains (step S
9, 10), the fuel cut is executed when the dashpot correction amount GDP becomes 0 (step S9, 5).

On the other hand, if the result of determination in step S3 is that it is not in the neutral state, it is further determined in step S7 whether or not the previous time was in the neutral state. Then, when the previous time was in the neutral state (that is, the state in which the neutral state is changed to the drive state for the first time this time, which is the second control mode), the fuel cut is performed to prevent the engine from falling. It is prohibited and the fuel injection amount Ti is calculated according to the operating state (step S1
0), fuel injection is executed based on this (step S
6).

On the other hand, if the previous state was not neutral (that is, if the drive state has continued since the last time)
In the range where the engine speed N is equal to or higher than the fuel cut speed Ncut ₂ , the fuel cut is executed after the dashpot correction amount GDP becomes 0.
If it is ut ₂ or less, fuel cut is prohibited regardless of the dashpot correction amount GDP.

Engine Rotational Speed Control by Control Valve Next, rotational speed control by the control valve will be described based on the flowchart of FIG.

After starting the control, first, various signals such as engine speed and throttle opening are read (step R1).

Next, in step R2, it is determined whether or not the throttle opening is fully closed. If not, the dashpot correction amount GDP corresponding to the current operating state is set (step R16). Then, this dashpot correction amount GDP is output to the control valve (step R10). The dashpot correction amount GDP is read from a map having the engine speed and the engine load as parameters.

On the other hand, when the throttle is fully closed, the dashpot correction execution flag GDPFlog is further checked in step R3, but since dashpot correction is not performed at the beginning (dashpot correction execution flag GDPFlog = 0),
In this case, the previous throttle opening is checked in step R4.

Here, if the throttle is fully closed last time, the idle speed control is executed because the idle operation state is continued. That is, in step R5 the target speed N ₀ corresponding to the engine temperature is set, in step R6 the basic control amount GB of the control valve corresponding to the engine temperature is set, and in step R7 the feedback correction amount is set.
In addition to setting GFB, other correction amounts GC are set in step R8.

Then, the final control amount G of the control valve is calculated from these correction amounts (step R9), and this is output to the control valve (step R10).

On the other hand, in step R4, when it is determined that the throttle opening was not fully closed last time (that is, when the throttle fully closed for the first time and the deceleration state is entered), it is necessary to perform the dashpot correction. First step
In R11, set the dashpot correction execution flag GDPFlog to 1
After that, it is determined in step R12 whether or not the dashpot correction amount GDP is 0. If GDP ≠ 0, the dashpot correction amount GDP is decremented by a predetermined value ΔGDP (step R15), and This is output to the control valve each time (step R10).

Then, when the correction amount GDP = 0, the correction amount GDP is set to 0 (step R13), and the dashpot correction execution flag GDPFlog is set to 0 (step R14).

By controlling the control valve in this way, the idle rotation control and the dashpot correction control are realized.

[Brief description of drawings]

FIG. 1 is a system diagram of a main part of an engine equipped with a fuel control device according to an embodiment of the present invention, FIGS. 2 to 4 are control time charts by the fuel control device, and FIGS. A control flowchart, FIG. 7 is a control time chart in a conventional general fuel control apparatus. 1 ... Engine 2 ... Intake passage 3 ... Exhaust passage 4 ... Air flow meter 5 ... Throttle valve 6 ... Injector 7 ... Bypass passage 8 ... Control valve 9 ... Spark plug 10 ... Control unit

Claims (1)

(57) [Scope of utility model registration request] 1. A fuel cut means for cutting fuel in a region equal to or higher than a first set rotational speed preset when decelerating an engine, and an intake air amount which is increased by a predetermined amount during deceleration, and the increase is performed at a predetermined damping rate. In an engine provided with a dashpot air supply means for reducing the amount, a rotation speed detection means for detecting an engine rotation speed and an engine rotation speed detected by the rotation speed detection means are on a higher rotation side than the first set rotation speed. When the engine speed is lower than the second set engine speed, the fuel cut is immediately executed regardless of whether or not the dashpot air supply means supplies the dashpot air when the engine speed is higher than the second set engine speed. Fuel cut control means for executing a fuel cut when the dashpot air falls below a predetermined amount. Engine fuel control device.