JPH055440A - Engine fuel controller - Google Patents

Abstract

(57) [Summary] [Purpose] The fuel injection is controlled at the time of starting so that a reliable starting can be performed with an appropriate air-fuel ratio regardless of the fuel remaining in the intake pipe. A fuel injection valve is controlled so that fuel injection and fuel injection stop are alternately repeated for a predetermined time until a complete explosion state is detected after the starter is activated. In this case, the fuel injection valve drive timing is set so that the predetermined time is lengthened according to the time elapsed from the start of the starter operation, and the initial fuel injection duration T ₁ is set longer.

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 starting an engine.

[0002]

2. Description of the Related Art In a fuel injection type engine, a fuel amount is usually calculated based on an intake air amount detected by an air flow sensor and an engine speed calculated from a crank angle signal. Control is performed such that correction is performed to set the final fuel amount, the fuel injection valve is driven by an injection pulse corresponding to the set fuel amount, and fuel is injected into the intake passage. Further, when the engine is started, it is usual to inject a preset fixed amount of fuel as described in, for example, Japanese Patent Publication No. 63-38537.

[0003]

The fuel adhering to the inner wall of the intake pipe during operation of the engine is vaporized in the intake pipe when the engine is stopped when the temperature is high, and it becomes stagnant fuel and is sucked into the combustion chamber at the next start. To be done. Therefore, it is necessary to set the fixed injection amount at the time of starting the engine in consideration of the amount of the retained fuel before starting. However, conventionally, the fixed injection amount at the time of starting is usually set by predicting the amount of stagnant fuel sucked into the combustion chamber and subtracting that amount. When there is more than expected, the fuel in the combustion chamber becomes too rich and there is a problem that a start failure occurs.

The present invention has been made in view of the above-mentioned problems, and it is possible to make an appropriate air-fuel ratio regardless of the fuel retained in the intake pipe, thereby making it possible to reliably start the engine fuel. The purpose is to obtain a control device.

[0005]

[Means for Solving the Problems]
The fuel control system, as shown in FIG.
An engine that injects a fixed amount of starting fuel with a fuel injector.
The starter operation in the fuel control system
The starter operation detection means and the complete
Explosion detection means, output of the starter operation detection means, and
The operation of the starter is detected in response to the output of the complete explosion detection means.
Fuel injection until the complete explosion of the engine is detected.
The fuel injection so that the fuel stop and the fuel stop are alternately performed every predetermined time.
Start-up fuel control means for controlling the device and starter operation detection
The time elapsed from the start of the starter operation after receiving the output of the output means
The fuel injection duration and the fuel stop duration accordingly.
Equipped with injection / stop duration setting means to lengthen each
It is characterized by

Here, the injection / stop continuation time setting means is
In response to the output of the starter operation detection means, the duration of the first fuel injection is set longer, and after that, the start of the starter operation is started by setting the duration of fuel stop and fuel injection shorter than the duration of the first fuel injection. It is better to make it longer depending on the elapsed time from.

[0007]

When the starter operates, the fuel control means at startup operates, and the fuel injection at startup is performed so that the fuel injection and the fuel injection stop (fuel cut) are alternately repeated for a predetermined time. At that time, the above-mentioned predetermined time, that is, the duration of fuel injection and the duration of fuel stop are set to be longer according to the elapsed time from the start of the starter operation. By alternately repeating fuel injection and fuel stop with such settings, when the first injection does not complete explosion, the fluctuation range of the air-fuel ratio is gradually increased while scavenging the retained fuel,
While avoiding the overshoot to the lean side, the air-fuel ratio is gradually approached to an appropriate value, whereby a reliable start is realized.

[0008] Here, by setting the initial fuel injection duration to be longer, it is possible to shorten the starting time during normal operation with less stagnant fuel.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments will be described below with reference to the drawings.

FIG. 2 is an overall system diagram of an embodiment of the present invention.

In this embodiment, a spark plug 3 is provided in the combustion chamber 2 of the engine 1, and the spark plug 3 is connected to an ignition coil 5 via a distributor 4. Further, an intake port 7 and an exhaust port 8 opening to the combustion chamber 2 are formed in the cylinder head 6 of the engine 1, and an intake valve 9 for opening and closing the intake port 7 and the exhaust port 8 is formed.
And an exhaust valve 10 is provided. A throttle valve 12 is provided in an intake passage 11 communicating with the intake port 7, and a hot-wire type air flow meter 13 is provided upstream of the throttle valve 12. Further, a bypass passage 14 that connects the upstream and downstream intake passages 11 of the throttle valve 12 is provided.
An SC valve 15 is provided. Further, a fuel injection valve 17 is arranged near the intake port 7 at a position further downstream of the surge tank 16 formed downstream of the throttle valve 12. Further, the exhaust port 8 communicates with the exhaust passage 18, a catalyst device 19 is provided in the exhaust passage 18, and an O ₂ sensor 20 located upstream of the catalyst device 19 for detecting the oxygen concentration in the exhaust gas is provided. It is arranged.

Fuel injection valve 17, ignition coil 5 and IS
The C valve 15 is operated by a control signal from a control unit 21 composed of a microcomputer. The control unit 21 uses the crank angle signal from the crank angle sensor attached to the distributor 4 and the air flow meter 13 as information for calculating the control signal.
The intake air amount signal from the O ₂ , the oxygen concentration signal from the O ₂ sensor 20, the starter switch signal, and the like are input.

The fuel injection amount is basically set based on the intake air amount detected by the air flow meter 13 and the engine speed calculated from the crank angle signal.

Further, when the engine is started, as shown in FIG. 3 (a), after the starter switch is turned on, fuel injection is performed so that fixed fuel injection and fuel cut are alternately repeated. At this time, the initial fuel injection duration T ₁ is set to be long, and the subsequent fuel cut time T ₂ is set to be shorter than T ₁ . Further, the second fuel injection duration T ₃ is set to the same length as the above T _2, and hereinafter, T ₄ (= T ₅ ), T ₆ (= T ₇ ), ...
.. are set to become longer in sequence. Then, such fuel injection is performed until the complete explosion state is detected.

When the fuel control as described above is performed when the engine is started, the air-fuel ratio (A / F) in the intake pipe fluctuates as shown in FIG. 3 (b). In this figure, for example, in the case shown by the solid line, the intake pipe is in a rich state (A / F is small) due to stagnant fuel at the time of starter operation, which changes to the rich side by the first fuel injection, and then The accumulated fuel is scavenged by the fuel cut, and the curve becomes such that the valleys and the mountains alternate by repeating the fuel cut and the fuel injection alternately. In that case, the fuel cut time and the fuel injection duration time are set to gradually increase, so the slope of the valley or mountain becomes gradually gentle,
Moreover, the base value of the fluctuation gradually shifts to the lean side, and in this example, the air-fuel ratio becomes appropriate during the fourth fuel injection duration T ₇ , and the complete explosion occurs. Similarly, in the example indicated by the alternate long and short dash line, complete explosion occurs during the third fuel injection duration T ₅ . Further, in the example indicated by the broken line, the fuel is in the lean state when the starter is operating, so the complete explosion occurs during the initial fuel injection duration T ₁ .

FIG. 4 is a flow chart for executing the control of this embodiment. This will be described below. Note that S1 to S
24 indicates each step.

In this flow, when starting, first the engine speed Ne is read in S1, and then S
At 2, it is determined whether the starter is on. Then, when the ON operation is performed, in S3, it is determined whether Ne is 300 rpm or less in order to see whether or not the complete explosion has occurred.
At 4, it is determined whether the first flag F ₁ is set.

Since the first flag F ₁ is not set at first, the routine proceeds to S5, the first flag F ₁ is set, and the first start injection is executed in S6. Then, the timer T is set to T in S7.
Set to ₁ to start, count down T in S8, see if T becomes zero in S9, return if it is not zero, and if it becomes zero, stop fuel injection in S10, In S11, the second flag F ₂ is set and the process returns. Then, after that, the timer T is determined in S9.
Until the value becomes zero, the first flag F ₁ is set in the determination in S4, so the process proceeds to S12, and in S12 the second flag F ₁ is set.
Looking at whether ₂ is standing or not, since F ₂ is not standing, the flow from S6 onward is repeated.

Then, when T becomes zero, the second flag F
_{When 2} is set, the process proceeds from S12 to S13, and it is checked in S13 whether the third flag F ₃ is set. Then, when it came in first in S13, since the still F ₃ is not set, the program proceeds to S14, to start by setting the timer T to another timer value T _2. Then, in S15, T is counted down, and in S16, it is checked whether T becomes zero. If T is not zero, the process returns until T = 0. When T = 0, injection is executed in S17. S1
At 8, the third flag F ₃ is set and the process returns.

When the third flag F ₃ is set in this way, S1
Since the determination of 3 is YES, the process proceeds to S19 this time to see if the fourth flag F ₄ is set. If not, the process proceeds to S20. Then, in S20, the timer T is set to the timer value T ₃ and started, and
A flow similar to S8 to S11 is followed and the fifth flag F ₅ is reached.
The stand, then see if the fifth flag F ₅ in step S21 standing, the process proceeds to the following flow.

As a result of alternately repeating the fuel injection and the injection stop as described above, if the engine speed Ne exceeds 300 rpm in the determination of S3, it means that the explosion is complete. In that case, the process proceeds to S22, and in S22, If YES in any flag, reset all flags and timers in S23, switch to normal injection in S24,
If neither flag is set, S2 is directly changed.
4 and execute normal injection.

On the other hand, if the starter is not turned on in the determination of S2, it means that the starter has not been started, and the process directly proceeds to S22.

[0023]

Since the present invention is configured as described above, scavenging can be reliably performed regardless of the accumulated fuel in the intake pipe, and thus the air-fuel ratio can be reliably set to an appropriate value for reliable startup. You can Further, by setting the initial fuel injection duration time to be longer, it is possible to shorten the starting time during normal operation when the amount of stagnant fuel itself is small.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of the present invention.

FIG. 2 is an overall system diagram of an embodiment of the present invention.

FIG. 3 is an explanatory diagram of control characteristics of the same embodiment.

FIG. 4 is a flowchart for executing the control of the same embodiment.

[Explanation of symbols]

 1 Engine 17 Fuel injection valve 21 Control unit

Claims (1)

Claim: What is claimed is: 1. A fuel control device for an engine, wherein a fixed amount of starting fuel is injected by a fuel injection device when the engine is started, and starter operation detecting means for detecting an operation of a starter, and a complete explosion of the engine. Receiving the complete explosion detecting means for detecting, the output of the starter operation detecting means and the output of the complete explosion detecting means, fuel injection and fuel stop until the complete explosion of the engine is detected after the operation of the starter is detected. And a fuel control means for controlling the fuel injection device so as to alternately perform the fuel injection device for a predetermined time, and the duration of the fuel injection and the fuel depending on the elapsed time from the start of the starter operation upon receiving the output of the starter operation detecting means. An engine fuel control device comprising injection / stop duration setting means for increasing the duration of each stop. 2. The injection / stop duration setting means receives the output of the starter operation detecting means to set a longer duration of the first fuel injection, and the subsequent duration of fuel stop and fuel injection. 2. The engine fuel control device according to claim 1, wherein the fuel injection control device for the engine according to claim 1, wherein the fuel injection control device is started from a setting shorter than the duration of the first fuel injection and is lengthened according to the elapsed time from the start of the starter operation.