JPH01159434A - Controller for fuel-injection engine - Google Patents

Abstract

PURPOSE:To cope with a rough idle after hot starting of an engine as well as to improve the extent of idling stability by compensating a fuel injection quantity at the time of idling for increment when the fundamental fuel injection quantity at the idling is large enough. CONSTITUTION:In a control unit 10 controlling a fuel injection valve 6, there is provided with a means 21 which operates a fundamental fuel injection quantity Tp corresponding to such a value that divided intake air quantity by engine speed, on the basis of each detection signal of an air flow meter 4 and an engine speed sensor 11. Also, there is provided with a means 23 which compensates an fuel injection quantity at idling for increment when this fundamental fuel injection quantity Tp is large, on the basis of the fundamental fuel injection quantity Tp at the idling. In addition, there is provided with a means 22 which operates a final fuel injection quantity Ti on the basis of the fundamental fuel injection quantity Tp, a fuel increment rate Cid and other various correction values alpha, etc. With this constitution, idling stability is improved by coping with a rough idle after hot starting of an engine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a control device for a fuel injection engine, and particularly to measures against rough idling.

(Prior art) Generally, in a fuel injection engine that controls fuel injection from a fuel injection valve by electronic control, a value corresponding to the intake air l detected by an air 70 meter divided by the engine rotation speed is calculated. This is the basic injection amount, and the fuel injection amount is controlled based on this. In other words, the basic injection amount is determined by multiplying the value obtained by dividing the intake air amount by the engine speed by a constant for conversion, and the final injection amount is determined from this basic injection amount and various correction values depending on the operating condition. The fuel injection valve is driven by an injection pulse having a pulse width corresponding to this.

By the way, in this type of engine, when the engine is restarted after being stopped before the engine temperature drops, vapor (fuel vapor) is likely to be generated in the fuel passage. Therefore, during idling operation immediately after hot start,
The vapor reduces the actual fuel injection amount, making combustion unstable and causing rough idle (unstable idle speed variation vJ).

As a countermeasure to this problem, it is known that the fuel injection amount is increased by a certain amount immediately after starting when the engine temperature is higher than a predetermined value (for example, Japanese Patent Application Laid-Open No. 1986
(See Publication No. 176426).

However, even during a hot start, the degree of vapor generation varies depending on the phase of the fuel type, such as alcohol-containing gasoline and normal gasoline, and other various conditions.
If the increase rate is small, it will not be possible to sufficiently suppress rough idle when a lot of vapor is generated, and if the increase rate is set high in advance, it will become overrich when little vapor is generated. However, it has not always been possible to achieve appropriate fuel control for rough idling suppression by simply performing uniform increase correction when the engine temperature is high immediately after startup.

(Object of the Invention) In view of the above circumstances, the present invention makes it possible to easily check the rough idle after a hot start, and based on this, it is possible to appropriately control the fuel injection amount and improve the idle stability. The present invention provides a control device for a fuel injection type engine that can perform the following steps.

(Structure of the Invention) In the present invention, a value corresponding to the intake air amount detected by the air flow meter divided by the engine speed is set as the basic injection amount, and the fuel injection 13 is controlled based on this value. In the fuel injection type engine, there is provided a calculation means for calculating the basic injection type, and a correction means for increasing the fuel injection amount at idle when the basic injection amount is large based on the basic injection amount at idle. It is prepared.

According to this configuration, when a rough idle occurs due to the generation of vapor during idle, such as after a hot start, the average engine speed decreases, and the basic injection 1ffi increases accordingly. The amount of fuel will be increased to compensate for this.

(Example) FIG. 1 shows an example of the present invention, and in this figure, 1
is an engine, 2 is an intake passage, and this intake passage 2 includes, in order from the upstream side, an air cleaner 3, an air flow meter 4 that detects the amount of intake air, a throttle valve 5 that opens and closes in response to accelerator operation, and an intake passage. A fuel injection valve 6 for injecting fuel into the passage 2 is disposed. The air flow meter 4 converts the amount of intake air into an electrical signal and outputs it, and its output is normally proportional to the reciprocal of the amount of intake air.

The fuel injection valve 6 has a control unit (ECLJ).
) 10, that is, fuel injection is performed by an injection pulse output from the control unit 10 for a time corresponding to the pulse width. This control unit 10 includes the air 70
- The output of the meter 4 is input, and the rotation speed sensor 11 detects the engine rotation speed, the intake air temperature sensor 12 detects the intake air temperature, the water temperature sensor 13 detects the engine cooling water temperature, and the opening degree of the throttle valve 5 is detected. Signals from the throttle opening sensor +J14, the gear switch 15, the starter switch 16, etc. are also input.

As shown in the above control unit, the base injection controller calculates the basic injection ff1Tp corresponding to the value obtained by dividing the intake air amount by the engine speed based on the outputs of the air 70 - meter < AFM) 4 and the rotation speed sensor 11. Inspection means 21 and basic injection h at idle
a correction means 23 that performs an increase correction based on lTp;
It includes a final injection amount calculation means 22 that calculates the final injection amount Ti based on the recorded main injection ff1Tp, the increase rate Cid by the correction means 23, various other correction values α, etc. In this embodiment, only when the correction condition determining means 24 determines that the condition is such that vapor is likely to occur, such as during idling after a hot start, the correction described in 1 is carried out for the time set by the timer 25. Basic injection I by means 23
The amount increase correction is performed according to Tp.

Further, the increase rate C1d has a characteristic as shown in FIG. 4 with respect to the basic injection ITp, that is, when the basic injection ITp is small, the increase rate Cid is set to 1 (no increase is performed).
However, as the basic injection ff1Tp increases beyond a predetermined value, the increase rate Cid is set to increase accordingly. Furthermore, in this embodiment, in order to further improve the compatibility with rough idle, the f/f is supplementarily increased depending on the engine speed.
ilcid is adjusted so that even when the basic injection mff1Tp is large, the increase rate C1d is made small if the engine speed is high. The increase rate Cid thus set according to the basic injection ff1Tp and the engine speed is stored in advance in the control unit 10 as a map 26, and is read out from this map 26.

A specific example of control by the control unit 10 is as follows:
This is shown in the flowchart of FIG.

This flowchart starts with the engine key turned on,
First, in step S1, the system is initialized and a flag FLG, which will be described later, is set to 0.

Next, in steps 82 and 83, the engine speed Ne and AFM output (air 70 - output of meter 4) are read, and in step S4, the engine speed Ne and the reciprocal of the intake air amount are Based on the AFM output U and a predetermined conversion constant (KxlOOOO), calculate the basic wA control pulse width (basic cutting force) - "p" as To=KX1000/(NextJ>).

Furthermore, in steps 85 to S7, the intake air temperature, engine water temperature,
Read each throttle opening.

Next, in step S8, the engine stall mode is determined to check whether the engine is stalled. If it is the engine stall mode, the final injection pulse width (final injection ff1) is determined in step S9.
) After setting ri to O, the process returns to step S2. Step S
If the determination in step 8 is No, in step S10, a backup mode determination is performed to check whether the backup v control is required to be performed due to an abnormality in the control system, etc., and if it is the backup mode, a predetermined Backup 1liITbu to final injection pulse width T
i, and then returns to step S2. If the determination in step Si is No, the starting mode is determined in step St2 to check whether or not the engine is starting. If it is in the starting mode, in step S13, the starting setting value - "S" is set to the invalid injection time "V". The value added is set as the final injection pulse Ti, and then the process returns to step S2.

When the determination in step S12 is No, that is, after the engine has finished starting, it is checked in step S14 whether the flag FLG is O. Since the flag FLG is O at the time when the engine starts, the process moves to step S15 and subsequent steps.

In step S15, a predetermined initial value is set in the timer.
Next, in step S16, the timer is counted down. Next, in order to check whether the conditions are such that vapor is likely to be generated in the fuel, the intake temperature is set (determined whether it is equal to or higher than i0 (step 517), and if this determination is YES, the water temperature is set to the set value. A determination is made as to whether or not the throttle opening is greater than or equal to the set value (step 818), and if this determination is YES, a determination is made as to whether or not the throttle opening is less than or equal to the set value (step 81g).When all of these determinations are YES, , step 82
0, the increase rate Cid is read from the map 26 of the basic injection pulse width Tp and the engine speed Ne, and step S21
If the value of the timer is checked and it is not O, then in step S22, the basic injection pulse width Tp and the above-mentioned geographical quantity rate C are
From id, various other correction values α, and BTv during invalid injection, the final injection pulse width °[1 is calculated as Ti=TpX(1+α 10 id) 1 TV, and this is output to the fuel injection valve 6.

As long as the conditions of steps 817 to S19 are satisfied, the above-mentioned increase rate Ci is
Perform earth dragon correction according to d. When it is determined in step S21 that the timer has reached 0, the flag FLG is set to 1.
At the same time, in step 824, the final injection positive 1 is calculated as T i =Tpx (1+α0)+TV and outputted to the fuel injection valve 6, thereby stopping the m increase correction. Then, proceed to step S2.

Note that if any of the determinations in steps Sv to S19 is No,
Even when , step S24 is performed via step 823.
After the flag FLG becomes 1, the process moves from the No determination in step S14 to step S24, thereby stopping the increase correction in these cases as well.

According to such control, the engine speed, basic injection pulse width To, and fuel increase rate C during idling after hot start
The changes in id and fuel injection amount are as shown in FIG. In other words, when one engine is completely turned off (ff1l) after starting, the engine speed drops to the idle speed, and if the combustion condition is normal, it will stabilize at this idle speed, but immediately after a hot start, there will be vapor in the fuel. When this occurs, a rough idle occurs in which the engine speed fluctuates unstably due to insufficient fuel injection 1 and poor combustion conditions (reference numeral 31). In this case, the average engine speed becomes lower, and the basic injection pulse width ``p'' becomes larger (33) compared to the case where rough idle does not occur (reference 33).
Code 32). Accordingly, steps 85 to S22 described above
The amount increase correction is performed by the process of , and the amount increase rate Cid is increased according to the basic injection pulse width TD as shown in FIG. 4 (reference numeral 34). This allows for computational fuel injection! )
1a is increased (code 35) compared to when rough idle does not occur (code 36), and the actual fuel injection due to vapor is 0.
The decrease in 4ffi is compensated for. Therefore, the combustion condition improves and rough idle is eliminated (reference numeral 31'
).

In this way, when a rough idle occurs due to the generation of vapor during idle immediately after a hot start, the amount of fuel injection is appropriately increased depending on the degree of rough idle. Further, even immediately after a hot start, when there is little vapor generation and no rough idle occurs, the fuel injection amount is not increased, and fuel overrich can be avoided.

(Effects of the Invention) As described above, the present invention provides the following advantages in a fuel injection engine:
Based on the basic injection amount 0-1 at idle, when this basic injection amount is large, the fuel injection amount at idle [1 is increased. When a rough idle occurs due to a lack of fuel, this can be easily checked by changing the basic injection amount, and the fuel injection amount can be appropriately increased and corrected accordingly. Therefore, it is possible to prevent overrich by avoiding unnecessary increase in fuel consumption when rough idle is not occurring, and also to prevent rough idle and improve idle stability.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the entire device showing an embodiment of the present invention, Fig. 2 is a functional block diagram of the means included in the control unit 1-, Fig. 3 is a control flow chart, and Fig. 4 is a fuel A characteristic diagram of the increase rate that corrects the increase in the injection amount according to the basic injection amount. Figure 5 is a time chart showing changes in the engine speed, basic injection amount, increase rate, and fuel injection aA amount during idling immediately after hot start. It is a chart. 1...Engine, 4...T anorometer, 6...
・Fuel injection valve, 10...control unit, 11
... rotation speed sensor, 21 ... basic injection amount calculation means,
23... Correction means. Figure 1 Figure 4 Figure 1p Figure 5

Claims (1)

[Claims] 1. In a fuel injection engine in which the basic injection amount is a value corresponding to the intake air amount detected by the air flow meter divided by the engine speed, and the fuel injection amount is controlled based on this value, The present invention is characterized by comprising a calculation means for calculating the basic injection amount, and a correction means for increasing the fuel injection amount at idle when the basic injection amount is large, based on the basic injection amount at idle. Control device for fuel-injected engines.