JPH03124937A - Fuel supply controller of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve operability by setting a composition compensation coefficient based on a detection value of a fuel composition detection means at the time when the fuel composition detection means is normally reset, and setting the composition compensation coefficient based on estimated mixed fuel composition which is at the other time. CONSTITUTION:When a fuel composition detection means B is judged to be abnormal by an abnormal judgement means I, any one of a composition compen sation coefficient and an air-fuel ratio feedback compensation coefficient is clamped to a specified value by an air-fuel ratio variation means J, and the other is forcibly varied, and a mixed fuel composition is estimated by a fuel composition estimation means K based on the detected real air-fuel ratio. Detec tion values of an estimation means K and a detection means B are compared by a normal judgement means L. When the detection means B is judged to be reset normally, the composition compensation coefficient is set based on the detection value of the detection means by a coefficient set means M, and at the other time the composed compensation coefficient is set based on the mixed fuel composition.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a fuel supply system for an internal combustion engine that uses a mixed fuel that is a mixture of a fuel such as methanol and another fuel such as gasoline.

<Prior Art> As a conventional example of this type of fuel supply device, there is the following (see Japanese Patent Laid-Open No. 56-98540).

In other words, by installing an alcohol concentration sensor in the fuel passage and correcting the fuel injection wall calculated from the engine operating state according to the detected alcohol concentration, fuel is supplied to the engine at the optimal air-fuel ratio for each alcohol concentration. I try to do that.

<Problems to be Solved by the Invention> However, in such conventional fuel supply devices, the optimum air-fuel ratio is ensured according to the alcohol concentration detected by the alcohol concentration sensor. If the system malfunctions, the alcohol concentration cannot be detected, so the fuel injection amount cannot be corrected to the optimum air-fuel ratio, resulting in poor drivability and, from a safety standpoint, discomfort for the driver.

Further, the output of the alcohol concentration sensor may momentarily exhibit an abnormal value due to a momentary interruption in a connector or the like or the introduction of noise, and then return to normal.

The present invention has been made in view of the above circumstances, and is capable of ensuring an appropriate air-fuel ratio when the alcohol concentration sensor is abnormal, and when the alcohol concentration sensor returns to normal, the air-fuel ratio is adjusted based on the sensor's detection 1α. An object of the present invention is to provide a fuel supply system for an internal combustion engine that can optimally control.

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention supplies a mixed fuel in which a plurality of fuels are mixed to an engine, and the fuel supply 9 is adjusted based on the engine operating state. a fuel supply amount setting means A for setting the composition of the mixed fuel; a fuel composition detecting means B for detecting the composition of the mixed fuel; an air-fuel ratio detecting means C for detecting the actual air-fuel ratio of the engine; composition correction coefficient setting means for setting a composition correction coefficient based on the composition correction coefficient; feedback correction coefficient setting means E for setting an air-fuel ratio feedback correction coefficient so that the detected actual air-fuel ratio becomes the target air-fuel ratio; a fuel supply amount correction means F that corrects the fuel supply amount based on the composition correction coefficient and the air-fuel ratio feedback correction coefficient; a drive control means H that drives and controls the fuel supply means G based on the corrected fuel supply amount;
Abnormality determination means (2) for determining an abnormality in the fuel composition detection means B, and forcibly setting either the composition correction coefficient or the air-fuel ratio feedback correction coefficient to a predetermined value when it is determined that the fuel composition detection means B is abnormal. an air-fuel ratio changing means J that clamps the air-fuel ratio and forcibly changes the other; and a fuel composition estimating means that estimates the mixed fuel composition based on the actual air-fuel ratio detected during the operation of the air-fuel ratio changing means J. , a normality determining means for comparing the detection (il) of the fuel composition estimating means with a detection value of the fuel composition detecting means B and determining whether or not the fuel composition detecting means B has returned to normal; and a fuel composition detecting means. When it is determined that B has returned to normal, a composition correction coefficient is set based on the detected value of the fuel composition detection means B; otherwise, a composition correction coefficient is set based on the estimated mixed fuel composition. A coefficient setting means M is provided.

<Operation> In this way, when it is determined that the fuel composition detection means is abnormal, the air-fuel ratio is forcibly varied and the composition of the mixed fuel is estimated from the air-fuel ratio. Further, after determining the abnormality, it is determined that the fuel composition detection means has returned to normal based on the estimated mixed fuel composition and the detected value of the fuel composition detection means, and a composition correction coefficient is set from the detected value of the fuel composition detection means, If the system does not return to normal, a composition correction coefficient is set based on the estimated mixed fuel composition.

<Example> An example of the present invention will be described below with reference to FIGS. 2 to 4.

In FIG. 2, a microcomputer 1 receives an intake air flow rate signal from an air flow meter 2, a reference signal (corresponding to the engine rotation speed) and a position signal from a crank angle sensor 3, and an exhaust passage 5 of an engine 4. An oxygen concentration signal from an oxygen sensor 6, which is installed as an air-fuel ratio detection means for detecting an air-fuel ratio from the oxygen concentration in exhaust gas, and a cooling water temperature signal from a water temperature sensor 7, which is installed in the fuel supply passage 8. A concentration detection signal from an alcohol concentration sensor 9 serving as fuel composition detection means is input.

The microcomputer 1 includes an l10IA and a CPU.
It is composed of an IB, a ROMIC, and a RAMLD, and based on the signals from the various sensors, etc.
The fuel injection amount is calculated and an injection pulse signal is output to a fuel injection valve 10 as a fuel supply means installed in the intake system of the engine.

Here, the microcomputer 1 has a fuel supply amount setting means, a composition coefficient setting means, a foot'/\・ink correction coefficient setting means, a fuel supply amount correction means, a drive control means, an abnormality determination means, an air-fuel ratio changing means, and a fuel supply amount setting means. It constitutes a composition estimation means, a normality determination means, and a coefficient setting means.

Next, the operation will be explained according to the flowcharts of FIGS. 3 and 4.

First, to explain fuel injection control, air flow meter 2
The intake air flow IQ detected by the crank angle sensor 3
From the engine rotational speed N detected by the basic injection amount T,
After calculating (=KQ/N; is a constant), the fuel injection amount T
, is calculated using the following equation.

']'; =TP XC0EFXαXALCXKBL
RC+1゛.

α is an air-fuel ratio feedback correction coefficient based on the detected value of the oxygen sensor 4, ALC is an alcohol correction coefficient as a composition correction coefficient according to alcohol concentration, KBLRC is a learning correction coefficient for the air-fuel ratio, and T is a correction bone for battery voltage. . Further, C0EF is various correction coefficients.

A pulse signal corresponding to the fuel injection amount 'r obtained in this way is output to the fuel injection valve 10 to supply mixed fuel to the engine.

During this fuel injection amount control, routines shown in the flowcharts of FIGS. 3 and 4 are executed. These routines are, for example, 100. ,. It is executed by time synchronization every 0.

That is, in Sl of FIG. 3, the alcohol concentration sensor 9
Determine whether or not it is abnormal, and if YES, proceed to S2 and N
When o, the routine is terminated. In this determination, an abnormality is determined when the output voltage of the alcohol concentration sensor 9 is out of the permissible range or when the rate of change of the output voltage is greater than or equal to a predetermined value.

Further, during the air-fuel ratio feedback control, if the air-fuel ratio sticks to the rich side or the one-in side for a predetermined time or more, it is determined that there is an abnormality.

In S2, it is determined whether the alcohol correction coefficient ALC has been clamped to a fixed value for NC, which will be described later. If YES, the routine is terminated, and if \0, the process proceeds to S3.

In S3, it is determined whether air-fuel ratio feedback control is being performed. If YES, the process proceeds to S4; if NO, the routine is ended.

In S4, it is determined whether the air-fuel ratio should be enriched based on a lean flag and a rich flag, which will be described later, and YE is determined.
If S, the process advances to S5, and if No, the process advances to S6. Here, when the air-fuel ratio is close to rich and the lean flag is on, the air-fuel ratio is made lean, and when the air-fuel ratio is close to lean and the rich flag is on, the air-fuel ratio is made rich. In S5, a fixed value (for example, equivalent to M50), which will be described later, is increased by a predetermined value in order to enrich the air-fuel ratio. As a result, the fuel injection amount is increased and the air-fuel ratio is enriched.

In S6, the fixed value is decreased by a predetermined value in order to lean the air-fuel ratio. As a result, the fuel injection amount is reduced and the air-fuel ratio is made lean.

In S7, it is determined whether the output of the oxygen sensor 6 has reversed with respect to the reference value, and if YES, it is determined that the calibration (estimation) conditions for the alcohol correction coefficient ALC are satisfied, and the process proceeds to S8.
If the answer is NO, the routine is terminated.

In S8, calibration (estimate) is performed based on the output of the oxygen sensor 6.
The alcohol correction coefficient determined by the alcohol concentration sensor 9 is compared with the alcohol correction coefficient based on the detected value of the alcohol concentration sensor 9, and whether or not the alcohol correction coefficient determined by the alcohol concentration sensor 9 is within a permissible range relative to the alcohol correction coefficient determined by the oxygen sensor 6. When the determination is YES, it is determined that the alcohol concentration sensor 9 has returned to normal, and the process proceeds to S9. When the determination is NO, it is determined that the abnormality of the alcohol concentration sensor 9 continues, and the process proceeds to SIO. Here, the reason why such a determination is made is that even after the alcohol concentration sensor 9 is determined to be abnormal, the detected value of the alcohol concentration sensor 9 returns to normal when the abnormality is determined due to a momentary interruption or the mixing of noise.

In S9, an alcohol correction coefficient ALC is set based on the detected value of the alcohol concentration sensor 9.

In SIO, the alcohol correction coefficient ALC calibrated based on the oxygen sensor 6 is set as a constant value for NG. The alcohol correction coefficient ALC is calibrated as follows. That is, the air-fuel ratio feedback correction coefficient α
The amount of change Δα from =1 (the amount of change until the clamping direction of the actual air-fuel ratio is reversed) is calculated.

Then, from the previous alcohol correction coefficient ALCOLD and the change amount Δα, a new alcohol correction coefficient ALC, .
, is calculated using the following formula.

A L C,, = A L C,, I, ±ALCoL
Then, the new calibrated alcohol correction coefficient ALC,l□ is stored in the RAM.

The calibration of the alcohol correction coefficient ALC, , 1, constitutes a means for estimating the fuel composition.

Next, the flowchart of FIG. 4 will be explained.

In Sll, it is determined whether the alcohol concentration sensor 9 is abnormal or not. If YES, the process advances to S12, and if NO, the routine is ended.

In S12, the alcohol correction coefficient ALC is
It is determined whether or not it has been clamped to the fixed value for G. If YES, the routine is terminated, and if NO, the routine proceeds to S13.

At Si2, it is determined whether the air-fuel ratio feedback correction coefficient α and the alcohol correction coefficient ALC are clamped based on the fixed flag, and if YES (when the fixed flag is on), the process advances to S14 and N.

If so, the process advances to S15.

In S14, it is determined whether air-fuel ratio feedback control is in progress. If YES, the process proceeds to S19, and if NO, the process proceeds to S2.
Go to 0.

In S15, the alcohol correction coefficient ALC is clamped to an identified value (for example, M2O).

At Si6, the air-fuel ratio feedback correction coefficient α is clamped to 1.

In Si2, clear the timer's Kalantoy recitation in WA4 direct for the first time.

At 318, the fixed flag is turned on and the routine ends.

In S19, the count value of the timer is counted up, and the process proceeds to S21.

At 320, the count value of the timer is cleared to the initial value.

In S21, based on the count value of the timer, the
It is determined whether a predetermined time (for example, 3 to 5 seconds) has elapsed since the time when 1 to 14 were satisfied, and if YES, the process advances to S22, and if NO, the routine is ended.

At 322, the time elapsed flag is turned on and the process proceeds to S23.

In S23, the alcohol correction coefficient ALC is clamped to a fixed value, and the air-fuel ratio feedback correction coefficient is clamped to 1, and the actual air-fuel ratio is clamped on the richer side than the stoichiometric air-fuel ratio based on the detected value of the oxygen sensor 6. It is determined whether or not, and if YES, the process advances to S24, and if NO, the process advances to S25.

When the actual air-fuel ratio is clamped on the rich side, S2
The lean flag is turned on at step S25, and when the actual air-fuel ratio is clamped on the lean side, the rich flag is turned on at step S25.

The flag set in this way is 84 in FIG.
used in

Here, the identified value M50 (or M4o-M2O) is the rich limit at which engine combustion is stable for gasoline, and the lean limit at which engine combustion is stable for high concentration methanol (M2S). By clamping the correction coefficient ALC, stable engine operation can be continued.

As explained above, when the alcohol concentration sensor 4 is determined to be abnormal, the air-fuel ratio feedback correction coefficient α
After calibrating the alcohol correction coefficient ALC based on the detected value of the oxygen sensor 6 by forcibly changing the alcohol correction coefficient ALC with the ALC clamped at 1, the alcohol concentration is determined from this calibration value and the detected value of the alcohol concentration sensor 9. sensor 9
When the alcohol concentration sensor 9 returns to normal, the alcohol correction coefficient ALC is set based on the detected value of the alcohol concentration sensor 9, while if the alcohol concentration sensor 9 continues to be abnormal. Since it is clamped to the calibrated fixed value for NG,
It has the following effects.

That is, when the alcohol concentration sensor 9 is momentarily interrupted or determined to be temporarily abnormal due to the introduction of noise, the alcohol correction coefficient is set based on the detected value of the alcohol concentration sensor 9 from the time the alcohol concentration sensor 9 returns to normal. Therefore, abnormality in the alcohol concentration sensor 9 can be determined with high precision, and the combustion injection amount can be optimally set according to the methanol concentration, so that the air-fuel ratio can be optimally controlled and drivability can be improved.

In addition, when the abnormality of the alcohol concentration sensor 9 continues, the N
Since it is clamped to a fixed value for G, the air-fuel ratio is appropriately controlled and drivability can be improved.

In addition, if the alcohol concentration sensor 9 is abnormal and the calibration is not completed, the alcohol correction coefficient ALC is set to a fixed value (
(equivalent to M50), so when the engine is stopped and restarted before calibration is completed,
It is possible to restart the engine even if the alcohol concentration changes due to refueling.

<Effects of the Invention> As explained above, the present invention provides, when the fuel composition detection means is determined to be abnormal, the fuel composition estimated based on the detected value of the air-fuel ratio detection means and the fuel composition detection means. When it is determined that the fuel composition detection means has returned to normal, the composition correction coefficient is set based on the detected value of the fuel composition detection means, and at other times, the composition correction coefficient is set based on the estimated fuel composition. Since the composition correction coefficient is set, the air-fuel ratio can be optimally controlled when normality is restored, and the air-fuel ratio can be optimally controlled even in abnormal conditions, improving driveability. Can be performed with high precision.

[Brief explanation of drawings]

FIG. 1 is a diagram corresponding to claims of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIGS. 3 and 4 are flowcharts of the same.

Claims (1)

[Claims] A device for supplying a mixed fuel made by mixing a plurality of fuels to an engine, comprising a fuel supply amount setting means for setting the fuel supply amount based on the engine operating state, and detecting the composition of the mixed fuel. a fuel composition detection means for detecting the actual air-fuel ratio of the engine; a composition correction coefficient setting means for setting a composition correction coefficient based on the detected actual mixed fuel composition; a feedback correction coefficient setting means for setting an air-fuel ratio feedback correction coefficient so that the air-fuel ratio becomes a target air-fuel ratio; and a fuel supply amount for correcting the set fuel supply amount by the composition correction coefficient and the air-fuel ratio feedback correction coefficient. A fuel supply device for an internal combustion engine comprising a correction means and a drive control means for driving and controlling the fuel supply means based on the corrected fuel supply amount, comprising: an abnormality determination means for determining an abnormality in the fuel composition detection means; an air-fuel ratio changing means for forcibly clamping one of the composition correction coefficient and the air-fuel ratio feedback correction coefficient to a predetermined value and forcibly changing the other when an abnormality is determined; and the air-fuel ratio changing means. a fuel composition estimating means for estimating a mixed fuel composition based on an actual air-fuel ratio detected during the operation of the fuel composition estimating means; and a fuel composition detecting means for comparing a detected value of the fuel composition estimating means with a detected value of the fuel composition detecting means. normality determining means for determining whether the means has returned to normal; and when it is determined that the fuel composition detecting means has returned to normal, a composition correction coefficient is set based on the detected value of the fuel composition detecting means; A fuel supply device for an internal combustion engine, comprising: coefficient setting means for setting a composition correction coefficient based on the estimated mixed fuel composition at other times.