JP2540185Y2 - Fuel injection control device for internal combustion engine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine, and more particularly to an improvement in a device for performing a wall flow correction of a fuel injection amount.

[0002]

2. Description of the Related Art A conventional fuel injection control device for an internal combustion engine is disclosed, for example, in Japanese Patent Application Laid-Open No. 2-215941. To explain the outline of this, the basic fuel supply amount T _P (= K · Q) corresponding to the amount of air taken into the cylinder by detecting the intake air flow rate Q and the number of revolutions N of the engine.
/ N; K is a constant) to correct the basic fuel supply amount _{TP according} to the engine temperature or the like, and to correct a response delay to a change in the amount of fuel adhering to the intake passage during acceleration / deceleration operation. The fuel supply amount T _I is finally set by performing the correction and the correction based on the battery voltage. Note that under predetermined operating conditions, the air-fuel ratio is set to a target air-fuel ratio (theoretical air-fuel ratio) based on a signal from an air-fuel ratio sensor (oxygen sensor) that detects the air-fuel ratio of the air-fuel mixture by detecting the oxygen concentration in the exhaust gas. The fuel injection amount is feedback-controlled.

[0003] Then, by outputting a driving pulse signal having a pulse width corresponding to the thus set fuel supply quantity T _I at a predetermined timing, so that injects supply a predetermined amount of fuel to the engine.

[0004]

By the way, in the conventional fuel injection control device which performs the wall flow correction during the acceleration / deceleration operation as described above, the control for feedback-controlling the normal engine speed to the target speed during idling is usually performed. The rotation of the engine is likely to fluctuate due to the operation performed, but in that case, if the wall flow correction is performed, the fuel injection amount fluctuates in synchronization with the fluctuation of the rotation. Was sometimes done.

The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a fuel injection control device for an internal combustion engine which avoids the acceleration of rotation fluctuation during idling.

[0006]

For this reason, the present invention, as shown in FIG. 1, employs an operating state detecting means A for detecting an engine operating state, and sets a basic fuel injection amount according to the detected engine operating state. Basic fuel injection amount setting means B and a wall flow correction amount for setting a wall flow correction amount corresponding to a change in the amount of fuel adhering to the intake passage wall in accordance with the change amount of the basic fuel injection amount during acceleration / deceleration operation of the engine. A fuel injection valve D for periodically injecting into the intake passage an amount of fuel obtained by correcting the basic fuel injection amount with a correction amount including the wall flow correction amount. The fuel injection control device is provided with a wall flow correction canceling means E for canceling the correction based on the wall flow correction amount during a steady idling operation of the engine.

[0007]

A predetermined proportion of the fuel injected from the fuel injection valve adheres to the intake passage wall, and during steady operation, the amount of adhered fuel is equal to the amount of adhered fuel supplied from the intake passage wall into the combustion chamber. However, during acceleration / deceleration operation, the amount of fuel adhering to the intake passage wall changes due to the change in the amount of fuel injected, whereas the change in the amount of fuel supplied from the passage wall is delayed. .

Therefore, during acceleration / deceleration operation detected by the operating state detecting means, the basic fuel injection amount set by the basic fuel injection amount setting means based on the steady state is set by the wall flow correction amount setting means. The engine output is corrected by the wall flow correction amount, and the corrected amount of fuel is injected and supplied from the fuel injection valve to the intake passage, whereby an engine output commensurate with acceleration / deceleration can be obtained.

On the other hand, during the steady idling operation detected by the operating state detecting means, the correction based on the wall flow correction amount is canceled by the wall flow correction canceling means, and as a result, the rotation fluctuation during idling is promoted by the wall flow correction. Can be avoided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2 showing the overall configuration of one embodiment, air is sucked into an internal combustion engine 1 through an air cleaner 2, an intake duct 3, a throttle chamber 4 and an intake manifold 5.

The intake duct 3 is provided with an air flow meter 6 for detecting an intake air flow rate Q. The throttle chamber 4 is provided with a throttle valve 7 interlocked with an accelerator pedal (not shown) to control the intake air flow rate Q. The throttle valve 7 is provided with a throttle sensor 8 for detecting the opening TVO by a potentiometer and an idle switch 9 which is turned on when the throttle valve 7 is idling below a predetermined opening.

The intake manifold 5 is provided with an electromagnetic fuel injection valve 10 for each cylinder, and injects fuel supplied from a fuel pump (not shown) under pressure to a predetermined pressure by a pressure regulator into the intake manifold 5. Supply. The control of the fuel injection amount is performed by a control unit 11 with a built-in microcomputer, the intake air flow rate Q detected by the air flow meter 6 and the engine speed N calculated based on a signal from a crank angle sensor 12 built in the distributor. And the basic fuel injection amount T _P
The final fuel injection amount T _I is calculated by correcting the basic fuel injection amount T _{P based} on the cooling water temperature and the like, and performing the wall flow correction described later during acceleration / deceleration. By outputting a drive pulse signal having a pulse width corresponding to the injection amount T _I to the fuel injection valve 10 in synchronization with the rotation of the engine, the required amount of fuel is injected and supplied to the engine 1.

An idle control valve 14 is interposed in an auxiliary air passage 13 provided to bypass the throttle valve 9,
Feedback control of the opening of the idle control valve 14 by a control signal from the control unit 11 so that the engine speed approaches the target speed set by the engine coolant temperature or the like at the time of idling when the idle switch 9 is turned on ( (Hereinafter referred to as ISC).

Further, a water temperature sensor 15 for detecting a cooling water temperature Tw in the cooling jacket of the engine 1 is provided.
An air-fuel ratio sensor 17 that detects the air-fuel ratio of the intake air-fuel mixture by detecting the oxygen concentration in the exhaust gas in the exhaust passage 16 is provided. Note that these various sensors and switches correspond to operating state detecting means. Hereinafter, the fuel injection amount setting routine by the control unit 14 will be described with reference to the flowchart of FIG. This routine is performed at predetermined intervals (for example, every 10 ms).

In step (denoted by S in the figure) 1, based on the intake air flow rate Q detected by the air flow meter 6 and the engine speed N calculated based on a signal from the crank angle sensor 12, the number of rotations per unit rotation is determined. the basic fuel injection quantity T _P corresponding to the intake air amount is calculated by the following equation. T _P = K × Q / N (K is a constant) In step 2, various correction coefficients COEF are set based on the cooling water temperature Tw detected by the water temperature sensor 15.

In step 3, a feedback correction coefficient α set based on a signal from the air-fuel ratio sensor 17 is read. The feedback correction coefficient α is set by another routine (not shown), but it is determined whether or not the current operating condition satisfies the operating condition for performing the air-fuel ratio feedback control. Based on the signal from the fuel ratio sensor 17, the value is periodically changed and set to maintain the target air-fuel ratio by proportional integral control or the like, but if the feedback control condition is not satisfied, it is clamped to the reference value and the feedback control is stopped. I do.

In step 4, a voltage correction amount T _S is set based on the battery voltage value. This is for correcting a change in the injection flow rate of the fuel injection valve 10 due to a change in the battery voltage. In step 5, the idle switch 9
N, OFF is determined. If it is determined that the idle switch 9 is OFF, the process proceeds to step 6, where the wall flow correction amount CHO
Calculate _Sn by the following equation.

CHOS _n = (T _P −AVT _P ) × GZTWC where AVT _P is a moving average value of T _P up to the previous time, GZT
WC is an acceleration / deceleration correction coefficient set by a search from a map table or the like according to the water temperature. Incidentally, next CHOS _n ≒ 0 for a T _P -AVT _P ≒ 0 at the time of steady operation,
Substantially no wall flow correction is performed.

On the other hand, if it is determined in step 5 that the idle switch 9 is ON, the routine proceeds to step 7, where the engine speed N and the target speed N set in the aforementioned ISC are set.
_The value is compared with a value obtained by adding a predetermined value θ to _0, and if N ≧ N ₀ + θ, it is determined that the vehicle is decelerating and the process proceeds to step 6;
If it is determined that N ₀ + theta determines the steady idle state close to the target rotational speed N _0, the routine proceeds to step 8 to cancel the wall flow correction by the CHOS _n CHOS _n =
Set to 0.

After step 6 or step 8, the program proceeds to step 9, where the final fuel injection amount T _I is calculated according to the following equation. In _{T I = T P × COEF ×} α + T S + CHOS n step 10, is set in the output register the computed fuel injection amount T _I. Consequently, when a fuel injection timing of a predetermined engine rotation synchronization, fuel injection is performed a drive pulse signal having a pulse width of the calculated fuel injection amount T _I is given to the fuel injection valve 10.

In this way, during steady idling, the wall flow correction is stopped, thereby preventing the fluctuation of the idling speed from being promoted, and the idling operation is stabilized and the idling operation performance is improved. In the routine, the function of step 1 corresponds to the basic fuel injection amount setting means, and the function of step 8 corresponds to the wall flow correction canceling means.

[0022]

As described above, according to the present invention, the wall flow correction of the fuel injection amount is canceled during the steady idling operation, so that it is possible to avoid the increase of the rotation fluctuation due to the wall flow correction, and thus the idle rotation And the driving performance can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of the present invention.

FIG. 2 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 3 is a flowchart showing a fuel injection amount setting routine of the embodiment.

[Explanation of symbols]

 Reference Signs List 1 internal combustion engine 6 air flow meter 8 throttle sensor 9 idle switch 10 fuel injection valve 11 control unit 12 crank angle sensor 15 water temperature sensor 17 air-fuel ratio sensor

Claims (1)

(57) [Scope of request for utility model registration] An engine operating state detecting means for detecting an engine operating state; a basic fuel injection amount setting means for setting a basic fuel injection amount in accordance with the detected engine operating state; Wall flow correction amount setting means for setting a wall flow correction amount corresponding to a change in the amount of fuel adhering to the intake passage wall according to a change amount of the injection amount, and correcting the basic fuel injection amount to include the wall flow correction amount A fuel injection valve that periodically injects the amount of fuel corrected by the amount into the intake passage, and wherein the correction by the wall flow correction amount is performed during steady idle operation of the engine. A fuel injection control device for an internal combustion engine, comprising wall flow correction canceling means for canceling.