JPS63113133A - Fuel supply control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To stabilize engine speed at idle and normal operating times by increasing or decreasing fuel supply for correction thereof to a cylinder causing changes in engine speed based on the changes in engine speed for a period of specified stroke of a each cylinder. CONSTITUTION:A control unit 11 calculates a fundamental fuel injection quantity based on detection values sensed by an air flow meter 3 and a crank angle sensor 7, making various corrections based on detection values sensed by a throttle opening sensor 5, a water temperature sensor 8, an O2-sensor 10, etc. When the engine speed is changed by excessive combustion or flameout, a cylinder causing the changes in engine speed is determined based on detection value sensed by the crank angle sensor 7. When fuel is supplied to the cylinder, the fuel supply is corrected by increasing fuel in case of flameout, or by decreasing fuel in case of excessive combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel supply control device for an internal combustion engine that is equipped with a fuel supply means such as a fuel injection valve for each cylinder. The present invention relates to a device in which the fuel supply amount is corrected for each cylinder so that the fuel supply amount is corrected for each cylinder.

<Prior Art> In a conventional electronically controlled fuel injection type internal combustion engine, the fuel injection amount Ti is determined, for example, by the following formula.

Ti-TpXCOEFXcr+Ts Here, Tp is the basic injection amount and is given by the following formula.

Tp like KXQ/N K is a constant, Q is the intake air flow rate, and N is the engine rotation speed. Also, C0EF is various increase correction coefficients, C0EF= 1 +Ktw+Kas+Kacc +Km
It is given by an expression such as r. Kt- is a water temperature increase correction coefficient, Kas is a starting and post-start increase correction coefficient + Kacc is an acceleration increase correction coefficient, and Kmr is a mixture ratio correction coefficient.

α is an air-fuel ratio feedback correction coefficient for performing air-fuel ratio feedback control (λ control) to be described later. Ts is a voltage correction element, which is used to correct variations in the injection amount due to fluctuations in the power supply voltage.

Air-fuel ratio feedback control involves installing an 02 sensor in the engine's exhaust system to detect the actual air-fuel ratio, and determining whether the actual air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio using a slice level. It controls the amount of fuel injection so that it approaches the stoichiometric air-fuel ratio.
It is controlled by changing the air-fuel ratio feedback correction coefficient α.

<Problems to be Solved by the Invention> However, such conventional electronically controlled fuel injection multi-cylinder internal combustion engines, particularly so-called multi-point injection internal combustion engines in which each cylinder has a fuel injection valve, have structural problems. Alternatively, if a difference occurs in the fuel injection amount of each fuel injection valve due to changes over time, etc., the distribution of fuel between the cylinders may not be uniform. As a result, if a specific cylinder misfires or, conversely, strong combustion (combustion pressure is too high) occurs, the engine speed will fluctuate greatly, and engine stability, especially idle stability, will deteriorate, leading to surging. Problems include problems such as a deterioration of the engine's output and fuel efficiency as well as a deterioration of the engine's output and fuel efficiency, or extremely deterioration of the exhaust characteristics from a specific cylinder when the engine is fully opened, leading to burnout of the three-way catalyst, etc. that functions as an exhaust treatment means. This results in a point.

The present invention was developed in view of the above-mentioned circumstances, and aims to accurately correct the deterioration of fuel distribution characteristics, thereby dramatically improving engine stability, improving output and fuel efficiency, and improving fuel efficiency. The purpose is to prevent burnout of the three-way catalyst.

Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. 1, in a fuel supply control device for an internal combustion engine having a fuel supply means for each cylinder, a rotation speed detection method for detecting the engine rotation speed is provided. basic fuel supply amount setting means for setting a basic fuel supply amount according to engine operating conditions including engine rotational speed; cylinder discrimination means for determining a cylinder in a predetermined stroke; and a predetermined stroke for each cylinder. a rotational speed change amount calculation means for calculating the amount of change in the engine rotational speed for each period; Fuel supply amount correction means for increasing or decreasing the basic fuel supply amount; and fuel supply means for a cylinder at the fuel supply timing determined by the cylinder determination means to send a fuel supply signal corresponding to the basic fuel supply amount or the corrected fuel supply amount. The fuel supply signal output means outputs the fuel supply signal to the fuel supply signal.

(Function) In such a configuration, the basic fuel supply amount setting means:
A basic fuel supply amount that is substantially common to all cylinders is set depending on the engine operating state.

On the other hand, the rotational speed detection means detects the engine rotational speed at each predetermined stroke period of each cylinder, and the rotational speed change amount calculation means calculates the amount of change in the engine rotational speed each time.

Then, the fuel supply amount correcting means corrects the basic fuel supply amount of the cylinder that affected the rotational speed change based on the amount of change in the rotational speed.

A fuel supply signal corresponding to the fuel supply amount corrected and set for each cylinder in this way is output from the fuel supply signal output means to the fuel supply means of the cylinder discriminated by the cylinder discrimination means, and the fuel supply signal is outputted from the fuel supply signal output means to the fuel supply means of the cylinder discriminated by the cylinder discrimination means. is supplied to the corresponding cylinder.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 2 showing the configuration of an embodiment, an air flow meter 3 for detecting the flow rate of intake air is installed in an intake passage 2 of an internal combustion engine 1 from the upstream side. Throttle valve 4. A throttle opening sensor 5 for detecting the opening of the throttle valve 4 and a fuel injection valve 6 as fuel supply means are provided for each cylinder. Further, a crank angle sensor 7 as an engine rotational speed detecting means, a water temperature sensor 8 for detecting cooling water temperature, and a 0□ sensor 10 for detecting the oxygen concentration in exhaust gas are provided in the exhaust passage 9.

The intake air flow rate signal Q from the airflow meter 3, the reference signal output from the crank angle sensor 7 at each predetermined stroke period of each cylinder (among them, the signal corresponding to a specific cylinder, for example, cylinder #l, is distinguished from the others) unit angle signal output for each tiny unit crank angle, throttle valve opening signal from throttle opening sensor 5, cooling water temperature signal from water temperature sensor 8, and 0□ sensor 10. The oxygen concentration signal from the is input to the control unit 11 containing a microcomputer,
1 sets the fuel injection amount (fuel supply if) according to the engine operating state detected based on each of these signals, and generates an injection pulse (fuel supply signal) having a pulse width corresponding to the injection amount.
The fuel injection control is performed by outputting this to the fuel injection valve 6.

Here, the fuel injection amount is set by setting the basic fuel injection amount according to the engine operating state, and then setting the fuel injection amount for each cylinder according to the change in the engine speed detected at each combustion stroke timing of each cylinder. The injection amount is adjusted to increase or decrease.

Hereinafter, the fuel injection amount control routine will be explained according to the flowcharts shown in FIGS. 3 to 5.

FIG. 3 shows a routine that is performed every time a reference signal is input from the crank angle sensor 7 and determines which cylinder is to be subjected to fuel increase/decrease correction.

In step (denoted as S in the figure) 1, the engine rotational speed N is detected as the reciprocal of the time (period) from inputting the reference signal from the previous crank angle sensor 7 to inputting the reference signal this time, and temporarily stores it.

In step 2, it is determined whether the reference signal is a cylinder discrimination signal for a specific cylinder (#1 cylinder), and if YES, the process proceeds to step 3 where data cyIld indicating the specific cylinder is output.
Set to .

After that, when the reference signal is input, the process advances to step 4 and the data cylD is counted up by 1, for example #2. #3
．． #4 cylinder has cylD set to 3,1゜2 respectively,
When the cylinder discrimination signal for the #1 cylinder is input again, cylD is reset to 0, and thereby each cylinder can be discriminated.

That is, the crank angle sensor 7 and the functions of steps 2 to 4 constitute cylinder discrimination means.

Next, in Step 5, the value obtained by subtracting a predetermined rotation Nl (for example, 6 rpm) from the previous engine rotation speed calculated in Step E is compared with the engine rotation speed calculated this time, and when the former exceeds the latter, that is, the rotation speed It is determined that the decrease is large, and in step 7, data (00) indicating that the fuel supply amount of the cylinder that caused the decrease should be corrected to increase is stored.

If the latter is determined to be greater than or equal to the former in step 5, the process proceeds to step 6, where the value obtained by adding the predetermined rotation N1 to the previous rotational speed is compared with the rotational speed calculated this time, and if the latter is less than or equal to the former. If this is the case, it is determined that the rotational speed is normal because the rotational speed is changing within the predetermined rotational speed N1, and in step 8, data (01) indicating that no increase/decrease correction is to be performed is stored.

In addition, when it is determined in step 6 that the latter exceeds the former, that is, when the increase in rotational speed is large, it is determined that strong combustion is occurring (the combustion pressure in the cylinder in the latest combustion stroke is too large), and in step 9 Data (02) indicating that the amount of fuel supplied to the cylinder determined to have deteriorated in twist firing should be corrected by reducing it is stored.

Here, the function of step 5.6 corresponds to the rotational speed change amount calculation means.

FIG. 4 shows a fuel injection amount calculation routine performed every unit time (for example, 10 m5).

In the figure, in step 11, the intake air flow i1Q is read from the air flow meter 3, and in step E2, the engine rotational speed N calculated in step 1 of FIG. 3 is read. However, the engine rotation speed N is proportional to the number of inputs of the unit angle signal from the crank angle sensor 7 per unit time.
may be calculated.

In step 13, the basic injection amount of fuel injected from the fuel injection valve 6 is calculated by the following formula based on the intake air flow rate Q and the engine rotational speed N. In steps 1 to 16, the cylinder to which the increased Nff1 correction is to be performed is determined.

That is, in step 14, the data cyID (0 to 4) of the discrimination cylinder stored in step 3 or step 4 in FIG.
Regarding 3), the cylinder in which the fuel increase/decrease correction is to be performed is determined. When the ignition order is #1-#3-#4-#2, a change in rotational speed due to misfire or strong twist firing is detected when the reference signal is input twice after the change, and based on this, cylD =00, in step 15 the cylinder seed data n is set to 4. When cyJD=1, n=2 in step 16
．． cyl! When D=1=2, n=1.
c) j! If it is D Mi 3, set n=3 in step 18.

In step 19, the combustion state data stored in steps 7 to 9 in FIG. 3 is determined.

If this data is a command (00) to increase the fuel supply amount in response to the misfire commanded in step 7, the process proceeds to step 20, and the fuel injection amount correction coefficient K of the #n cylinder is executed.
Set n to the previous value! (0,1%), and in step 21 this value is set to the maximum value KnMAX (for example +5 to
+10%) is reached, and if so, in step 22, =KnMax is set. The data also indicates a command to reduce the amount of fuel supplied for strong twist firing.
2), the process proceeds to step 22 and similarly sets the fuel injection amount correction coefficient to 7 to a predetermined value ffi (0, 1
%), and in step 24 this value is reduced to the minimum value, 1,
It is determined whether or not it has become less than 10% (for example, -5 to -10%), and if YES, it is set to KnNIN in step 25.

Also, if the data is normal and no increase/decrease correction is performed (
ol), the process proceeds to step 26, where the previous value of Kn is set as the current value.

Here, steps 7 to 9 in Figure 3 and step 2 in Figure 4
The functions 0 to 25 constitute the fuel supply amount correction means.

Next, in step 27, the final fuel injection 1iTi is calculated using the following equation.

Ti=Tp-COEF-cr・(1+Kn)+Ts Here, C0EF is various correction coefficients determined based on the throttle valve opening, cooling water temperature, etc., and α is the air pressure coefficient determined based on the oxygen concentration in the exhaust gas. It is a fuel ratio feedback correction means, where Kn is the correction coefficient for #n (nl to 4) cylinders, and Ta is a correction factor based on battery voltage.

The thus corrected fuel injection amount is injected and supplied from the fuel injection valve 6 at a predetermined crank angle timing of each cylinder, which is set based on the engine operating state.

This injection valve operation routine will be explained with reference to FIG.

This routine is interrupted when the value counted by the counter matches the injection timing.

In Step 7, the cylinder is discriminated based on the value of cyID, and an injection pulse having a pulse width corresponding to the fuel injection fiTi is output to the fuel injection valve 6 of the cylinder discriminated in Steps 32 to 35. Here, the functions of steps 32 to 35 constitute fuel supply signal output means. Next, in steps 36 to 39, ~ is added to the correction coefficient used this time in preparation for the next calculation.
4 is stored as the previous value.

Next, the effect when such control is performed will be explained based on FIG. 6.

Now, when cylinder #1 misfires during the combustion stroke, the combustion pressure of this cylinder decreases, resulting in a decrease in the average effective pressure Pi, and accordingly, the rotational speed decreases.

This decrease in rotational speed is detected when the reference signal for the #4 cylinder is input, and at that time, the correction coefficient for the #1 cylinder is increased by 1, so the next fuel injection amount is increased, and this causes the cylinder's correction coefficient to increase by 1. Combustion pressure increases and average effective pressure recovers.

Further, as shown in the figure, when strong twist firing occurs in the #2 cylinder, the average effective pressure Pi increases due to the increase in combustion pressure, and the rotational speed increases accordingly.

In this case, an increase in rotational speed is detected when the reference signal for #3 cylinder is input, and the correction coefficient for #2 cylinder is reduced by 2, which reduces the combustion pressure of the cylinder and makes the average equal to the dynamic pressure. Control the rise.

By adjusting the fuel injection amount in this way, it is possible to equalize the average effective pressure for each cylinder, suppress rotational fluctuations during idling and steady driving, prevent surging, and prevent burnout of the three-way catalyst. It is also possible to prevent the occurrence of

In this example, only the cylinder in which the misfire and double-twist firing occurred was corrected, but the amount was increased only for the cylinder that had a tendency to misfire.
The other cylinders are reduced by the amount increased / (number of cylinders - 1), and finally only for cylinders with a strong combustion tendency: $i amount is performed, and the other cylinders are increased by the amount reduced / (number of cylinders - 1). good. This is to maintain good exhaust emission, fuel efficiency, and catalytic performance by keeping the total amount of fuel constant, since misfire combustion does not occur continuously.

<Effects of the Invention> As explained above, according to the present invention, the fuel supply amount is corrected to increase or decrease the amount of fuel supplied to the cylinder that is the cause of the change in accordance with the change in engine rotational speed during a predetermined stroke time period of each cylinder. As a result, changes in rotational speed due to misfire and combustion can be suppressed within a short period of time, stabilizing the rotational speed during idling and steady driving, preventing surging, and preventing burnout of the three-way catalyst. You can get the effect that you can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a diagram showing the configuration of an embodiment of the present invention, FIG. 3 is a flowchart showing the combustion state determination routine of the same embodiment, and FIG. 4 is the same. FIG. 5 is a flowchart showing the fuel injection amount calculation routine, FIG. 5 is a flowchart showing the fuel injection pulse output control routine, and FIG. 6 is a time chart showing the combustion state of each cylinder.

Claims (1)

[Claims] In a fuel supply control device for an internal combustion engine, which includes a fuel supply means for each cylinder, a rotation speed detection means detects the engine rotation speed, and a basic fuel supply amount is set according to the engine operating state including the engine rotation speed. Basic fuel supply amount setting means;
Cylinder discrimination means for discriminating a cylinder in a predetermined stroke; rotation speed change amount calculation means for calculating the amount of change in engine rotation speed for each predetermined stroke period of each cylinder; a fuel supply amount correction means for increasing or decreasing the basic fuel supply amount in a direction to eliminate the change for the cylinder that affected the change; and a fuel supply corresponding to the basic fuel supply amount or the corrected fuel supply amount. 1. A fuel supply control device for an internal combustion engine, comprising fuel supply signal output means for outputting a signal to a fuel supply means of a cylinder whose fuel supply timing is determined by a cylinder determination means.