JPH0447130B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine fuel supply device that increases the amount of fuel when the engine accelerates.

[Prior Art] A fuel supply system for an engine that secures acceleration performance by increasing the amount of fuel for acceleration is well known (see Japanese Patent Laid-Open No. 116522/1983).

As a method for determining acceleration in this case, a method is known in which acceleration is determined when the throttle opening is less than a certain value and the rate of change in the throttle opening is greater than a predetermined value.

This control method is advantageous in that it can detect when acceleration actually requires an increase in fuel amount, compared to a simple method that determines acceleration when the throttle opening exceeds a set value.

However, the constant value that serves as the reference for the acceleration determination is set in accordance with the state after the engine has warmed up. However, when the engine is cold, the engine load increases due to factors such as high oil viscosity, which increases the throttle opening and also causes poor fuel vaporization and atomization, which causes the fuel to flow into the intake pipe. As a result, a fuel shortage occurs even when accelerating from a high opening, so if the throttle opening is set according to the condition after warming up as described above, acceleration during cold Drivability deteriorates. In addition, there is a problem in that fuel consumption during warm-up deteriorates when meeting the requirements during cold conditions.

[Object of the Invention] An object of the present invention is to provide an engine fuel supply device that can compensate for poor fuel vaporization and atomization performance by easing the acceleration criteria when the engine is cold. It is.

[Configuration of the Invention] Therefore, the present invention provides a throttle opening degree detection means for detecting the opening degree of a throttle valve, a throttle opening degree change rate detection means for detecting a rate of change in the opening degree of the throttle valve, and a throttle opening degree detection means for detecting the rate of change in the opening degree of the throttle valve. In an engine fuel supply system, the engine fuel supply device is equipped with a fuel increase means for increasing the amount of fuel by determining that acceleration is occurring when the throttle opening is less than the set opening and the rate of change of the throttle opening is equal to or higher than the set speed. An engine temperature detection means detects the engine temperature, and based on the output of the engine temperature detection means, when the engine temperature is low, the set opening degree is corrected to be larger than that when the engine temperature is high, and the acceleration judgment criterion for the fuel increase means is set. The invention is characterized by the provision of means for alleviating this.

[Effects of the Invention] According to the present invention, since the acceleration determination criteria are relaxed when the engine is cold, it is possible to increase the amount of fuel by acceleration correction up to a larger throttle opening, which improves the acceleration performance when the engine is cold. On the other hand, after the engine has warmed up when fuel vaporization and atomization are good, the acceleration criteria are narrowed down, so unnecessary fuel increases are suppressed and fuel efficiency is not worsened. It's over.

[Embodiments] Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.

As shown in Fig. 1, the engine E is equipped with an air cleaner 1, an air flow meter 2 for detecting the amount of intake air, a throttle valve 3 that opens and closes depending on the load of the engine E, and a fuel injection valve 4 in order from the upstream side. It includes an intake passage 5 and an exhaust passage 7 in which a catalytic exhaust gas purification device 6 is interposed.

A control unit 8 that executes control over the fuel injection valve 4 is composed of a microcomputer, and is configured to measure the intake air temperature AT detected by an intake air temperature sensor 9 provided with a sensor section facing inside the air cleaner 1, and an air flow meter 2. The intake air amount Tp detected by , the engine rotational speed N _E detected from the rotational speed of the distributor 11 of the ignition system 10 of the engine E, and the cooling water passage 12 of the engine E.
The cooling water temperature WT detected by the water temperature sensor 13 provided for the throttle valve 3, the throttle opening θ detected by the opening sensor 14 provided for the throttle valve 3, and the catalytic exhaust gas in the exhaust passage 7. The air-fuel ratio rich/lean signal Vs detected by the O ₂ sensor 15 provided upstream of the purification device 6 is used as input data.

In FIG. 1, reference numerals 16 and 17 are solenoid valves and air valves which are provided with two bypass passages 18 and 19 provided by bypassing the throttle valve 3 of the intake passage 5, respectively.
is driven by the control unit 8 on a duty basis to maintain the idle speed at the target speed during idling operation after warming up the engine. Also,
The air valve 17 is fully opened during idling operation when the engine is cold, and supplies the necessary bypass air downstream of the throttle valve 3 to prevent deterioration of combustibility.

Next, the fuel control executed by the control unit 8 will be specifically explained with reference to FIG.

When the control is started, in step #1, the intake air temperature AT, intake air amount Tp, engine speed N _E , cooling water temperature WT, throttle opening θ, and O ₂ sensor signal are determined.
Load Vs.

In step #2, in relation to the read cooling water temperature WT, the reference opening degree TA _ACC for acceleration increase determination, which is the first condition for fuel correction during acceleration, is read from a preset table.

As shown in Fig. 3, this table shows that when the cooling water temperature WT is lower than the preset cooling water temperature WT ₀ , the reference opening TA _ACC for acceleration increase determination increases in inverse proportion to the cooling water temperature WT. It is set. And the cooling water temperature WT is the set cooling water temperature
When WT is ₀ or more, regardless of the cooling water temperature WT,
It is set to a certain opening.

Then, in step #3, the current throttle opening θ is set to the reference opening for determining acceleration increase.
It is determined whether TA is smaller than _ACC . If the throttle opening degree θ is equal to or greater than the reference opening degree _TAACC for determining acceleration increase, no acceleration increase is performed, so the acceleration increase correction coefficient _CACC is set to zero in step #4.

on the other hand. If the throttle opening θ is smaller than the reference opening TA _ACC for determining acceleration increase, in step #5, the difference Δθ between the previous throttle opening θn-1 and the current throttle opening θn is calculated, and step #5 is performed. In step 6, it is determined whether this difference Δθ is larger than the second condition, which is the reference change degree DTA _ACC for determining acceleration increase. This reference degree of change DTA _ACC is set to determine whether or not it is an acceleration, and the change Δθ in throttle opening θ is determined by this reference degree of change DTA _ACC.
When the value exceeds C ACC , it is determined that the vehicle is accelerating, and the process moves to step #7 where the acceleration increase correction coefficient C _ACC is determined.
Read from the table. This table is the second
As shown in frame A of the figure, the throttle opening change amount Δθ increases in proportion to the change amount Δθ until it reaches a predetermined value, and remains constant after the predetermined value. The correction coefficient C _ACC is determined.

Throttle opening change amount Δθ is the reference change amount above.
When it is smaller than DTA _ACC , the first condition for acceleration increase is satisfied but the second condition is not satisfied, so the process moves from step #6 to step #4, and the acceleration increase correction coefficient _{C_ACC} is set to zero.

After reading the acceleration increase correction coefficient _CACC corresponding to the throttle opening change amount Δθ in step #7, or after setting the acceleration increase correction coefficient _CACC to zero in step #4, proceed to step #8. Then, other correction coefficients C _AT , C _WT , and C _FB are calculated.

The intake temperature correction coefficient C _AT is determined by an intake temperature correction table (not shown) so that it becomes large when the intake temperature is low to compensate for a decrease in engine combustibility. Similarly, the water temperature correction coefficient C _WT is also
When the engine is cold and the engine cooling water temperature is low, it is determined by a water temperature correction table (not shown) that the amount of fuel is corrected to increase.

Further, the feedback correction coefficient _CFB is set according to the rich/lean signal Vs of the air-fuel ratio detected by the O ₂ sensor 15 when the operating state of the engine E is in a so-called feedback control operating region.

Then, in step #9, the fuel injection valve 4
The current fuel injection pulse width Ti is calculated using the following equation.

Ti = Tp × 2 × Ck × C _AT × (1 + C _WT + C _FB + C _ACC + C _DEC ) + Tv In the above equation, Ck is the so-called control gain constant, C _DEC is the correction coefficient during deceleration, and Tv is the preset basic is the fuel injection pulse width.

After calculating the fuel injection pulse width Ti in this manner, when it is determined in step #10 that the fuel injection timing has been reached, one fuel injection is performed by the fuel injection valve 4 in step #11. .

As described above, when the engine E is cold and the engine coolant temperature WT is low, the reference opening TA _ACC , which is the first condition for determining acceleration increase, is changed to become larger, and the determination condition is relaxed accordingly. When the engine is cold and has poor combustion performance, the acceleration amount is increased even when acceleration is performed from a slightly larger throttle opening, which compensates for the poor combustion performance and allows good engine output to be obtained. Become.

In the above embodiment, the engine temperature is detected by the water temperature sensor 12, but the present invention is not limited to this, and for example, the engine ambient temperature may be detected.

[Brief explanation of the drawing]

Fig. 1 is a system configuration diagram showing a fuel supply system for an engine according to an embodiment of the present invention, Fig. 2 is a flowchart of fuel control executed by the control unit, and Fig. 3 is a reference opening degree for determining acceleration increase.
It is a graph showing a setting example of TA _ACC . 2... Air flow meter, 3... Throttle valve, 4... Fuel injection valve, 8... Control unit, 11... Distributor, 12... Water temperature sensor, 14... Throttle opening sensor.

Claims (1)

[Scope of Claims] 1. Throttle opening degree detection means for detecting the opening degree of the throttle valve; Throttle opening degree change rate detection means for detecting the rate of change in the opening degree of the throttle valve; and a fuel increase means for increasing the amount of fuel by determining that acceleration is occurring when the throttle opening change rate is equal to or higher than a set speed. and upon receiving the output of this engine temperature detection means,
Fuel supply for an engine, characterized in that the fuel supply for an engine is characterized in that it is provided with means for relaxing the acceleration determination criterion of the fuel increase means by modifying the set opening degree to be larger when the engine temperature is low compared to when the engine temperature is high. Device.