JPH04101032A - Fuel feeder of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve stability of engine driving at abnormality of an alcohol concentration detecting means at starting of an engine after concentration calibration and immediately after feeding fuel by estimating concentration of fuel after feeding, and by correcting a fuel supply amount using this estimated value so as to obtain a value close to an actual alcohol concentration. CONSTITUTION:Alcohol concentration in fuel is detected by a means A and a fuel supply amount is corrected and set by a means B based on this detected value. Also, when abnormality of the means A is judged by a means C, the alcohol concentration is estimated by a first means E based on air/fuel ratio detected by a means D. Moreover, when a means F judges that fuel is fed, the fuel alcohol concentration after feeding is estimated by a second means H from a detection output from a fuel amount detecting means G based on a residual amount and a fed amount of the fuel. And when, for example, it is judged that the above means A is abnormal and that an estimating motion of the first means E is not finished, a fixed value which is set in advance is switched to the estimated value of the second means H as an initial value after a lapse of predetermined time.

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 of alcohol and gasoline, and in particular to a fuel supply system when an alcohol sensor detecting alcohol concentration is abnormal. Regarding control technology.

<Prior Art> In this type of fuel supply device, an alcohol sensor is provided in the fuel tank to detect the alcohol concentration in the fuel, and the fuel supply amount is corrected based on the detected alcohol concentration.

As such a fuel supply device, some have been previously proposed by the applicant (for example, Japanese Patent Application No. 1-2622).
(See No. 50, etc.)

Fuel supply control of such a fuel supply device will be briefly explained.

In normal cases, the basic supply amount Tp (= -Q/N; is a constant) calculated based on the detected intake air flow rate Q and engine rotational speed N is added to the operating state and After adding correction according to the alcohol concentration detected by the alcohol sensor, the final fuel supply amount Ti (= Tp - COEF
・Calculate α・ALC+Ts). Here, C0EF is various correction coefficients depending on engine operating conditions such as cooling water temperature, α is an air-fuel ratio feedback correction coefficient, ALC is an alcohol concentration correction coefficient, and Ts is a battery voltage correction coefficient. Then, a signal with a pulse width corresponding to the calculated fuel supply amount Ti is output to the fuel injection valve to supply fuel to the engine.

On the other hand, if the alcohol sensor malfunctions and it becomes impossible to detect the alcohol concentration, the alcohol concentration is estimated based on the air-fuel ratio detection signal from the oxygen sensor, and the alcohol concentration correction coefficient ALC is calculated based on this estimated value. The fuel supply amount is corrected by setting. Note that until the estimated value is calculated, the alcohol concentration is fixed at a preset fixed value (for example, alcohol concentration 50%).

<Problems to be Solved by the Invention> However, when the alcohol sensor fails, refueling may be performed when the engine is stopped, and in this case, the alcohol concentration may change depending on the composition of the refueled fuel.
It is necessary to estimate the alcohol concentration based on the air-fuel ratio again. However, since the above-mentioned conventional device is not provided with a refueling determination function, it cannot determine whether refueling has been performed when the vehicle is stopped.

For this reason, in conventional devices, assuming that refueling is performed when the engine is stopped, the estimated alcohol concentration value by the oxygen sensor is gradually adjusted to the preset fixed value after the engine is started, regardless of whether or not refueling is performed. When the alcohol concentration reaches a fixed value, the alcohol concentration of the fuel after refueling is estimated.

Therefore, conventionally, after starting the engine when the alcohol sensor fails, the vehicle must be driven with the alcohol concentration set to a fixed value, albeit temporarily.

Additionally, if the engine stops after the engine is started but before a new estimated value is calculated, there is a problem that the engine will be operated using a fixed value as the initial value for the alcohol concentration when starting the engine thereafter. be.

The present invention has been made in view of the above circumstances, and provides a fuel supply device that can control the supply of mixed fuel using as accurate an estimated alcohol concentration as possible when the actual alcohol concentration cannot be detected. The purpose is to

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention includes an alcohol concentration detection means for detecting the alcohol concentration in fuel, and a fuel supply system based on the detected value of the alcohol concentration detection means. A fuel supply amount setting means for correcting and setting the fuel supply amount, an abnormality determination means for determining whether or not there is an abnormality in the alcohol concentration detection means, an air-fuel ratio detection means for detecting an air-fuel ratio of the engine, and an alcohol concentration detection means. a first concentration estimating means for estimating the alcohol concentration based on the air-fuel ratio detected by the air-fuel ratio detecting means when an abnormality is determined; and an estimation for determining whether the estimating operation by the first concentration estimating means has been completed. Completion determining means;
An engine start detection means for detecting the start of the engine; a refueling fuel instruction means for instructing the refueling fuel to be a specific fuel when the alcohol concentration detecting means is determined to be abnormal; and a refueling fuel instruction means for detecting the amount of fuel in the fuel tank. a fuel amount detecting means, a refueling determining means for determining whether or not refueling has been performed based on a detection output of the fuel amount detecting means, and a detection output of the fuel amount detecting means when it is determined that refueling has been performed. a second concentration estimating means for estimating the fuel alcohol concentration after refueling based on the remaining fuel amount and the refueling amount; When the input alcohol concentration value is determined to be abnormal in the alcohol concentration detection means and when it is determined that the estimation operation of the first concentration estimation means has been completed, the estimated value of the first concentration estimation means is set as the initial value and after a predetermined period of time has elapsed. When the alcohol concentration detection means is determined to be abnormal and the estimation operation of the first concentration estimation means has not been completed, a preset fixed value is set as the initial value. and a concentration switching means for switching to the estimated value of the second concentration estimating means after a lapse of time.

<Function> In the above configuration, normally, the fuel supply amount is set by correcting the fuel supply amount according to the detected value of the alcohol concentration detection means, and when the alcohol concentration detection means is determined to be abnormal, the fuel supply amount is set. , the alcohol concentration is estimated based on the detected air-fuel ratio, and the fuel supply amount is corrected based on the estimated value to set the fuel supply amount until the next refueling is performed. Further, when the alcohol concentration detection means is abnormal, an instruction is given to inform the occupant that the fuel to be refueled should be a specific fuel.

When it is determined that refueling has been performed, the alcohol concentration after refueling is estimated from the remaining amount of fuel and the amount of refueling at that time.

When starting the engine after refueling, if the estimation of the alcohol concentration based on the air-fuel ratio has already been completed, the estimated value based on the air-fuel ratio is set as the initial value, and after a predetermined period of time, the amount of fuel in the tank after refueling is determined. If the estimation of the alcohol concentration based on the air-fuel ratio has not been completed, a preset fixed value is set as the initial value, and after a predetermined period of time, the fuel in the tank after refueling is switched to the estimated value. The amount of fuel supplied is corrected by switching to the estimated value estimated from the amount.

<Example> Hereinafter, one embodiment of the present invention will be described based on the drawings.

In Figure 2, input/output interface (Ilo) I
A, a control unit 1 having a built-in microcomputer configured with a CPUIB, a ROMIC, and a RAMID receives an intake air flow rate signal from an airflow meter 2, a reference signal and a unit signal from a crank angle sensor 3, and an engine 4. An oxygen concentration signal from an oxygen sensor 6, which is installed in the exhaust passage 5 and serves as an air-fuel ratio detection means for detecting the air-fuel ratio from the oxygen concentration in the exhaust gas, a cooling water temperature signal from the water temperature sensor 7, and a fuel supply passage 8. A concentration detection signal from an alcohol sensor 9 as an alcohol concentration detection means installed in the engine, an ON/OFF signal from a starter switch 10 as an engine start detection means that is turned ON at the time of engine startup, and fuel in a fuel tank (not shown). A fuel remaining amount signal from a remaining amount sensor 11 serving as a fuel amount detection means for detecting the remaining amount is input.

Then, the control unit 1 calculates the basic supply amount Tp (= -Q/N; K is a constant) from the intake air flow rate Q and the engine rotational speed N, as described above, and calculates the basic supply amount Tp (= to -Q/N; K is a constant), and After adding corrections according to the state and alcohol concentration, the final fuel supply amount Ti (=Tp-CO
EF・α・ALC+Ts) is calculated. Then, a signal with a pulse width corresponding to the supply amount Ti is output to the fuel injection valve 12 provided for each cylinder at a predetermined timing synchronized with the rotation of the engine 4. The fuel is injected and supplied to the intake system of the engine. Therefore, the calculation process of the fuel supply amount Ti executed by the control unit 1 corresponds to fuel supply amount setting means. In addition, when the alcohol sensor 9 is abnormal, the control unit 1 displays a methanol replenishment prohibition display on the display device 13, which serves as a refueling fuel instruction means provided in the vehicle, in order to quickly instruct the fuel to be refueled to be a specific fuel (for example, gasoline). The alcohol sensor abnormality is displayed, and the alcohol concentration is set in accordance with the flowchart shown in FIG. 3 when the alcohol sensor 9 is abnormal.

Here, the functions of the abnormality determining means, the first concentration estimating means, the estimation end determining means, the refueling determining means, the second concentration estimating means, and the concentration switching means are carried out within the control unit 1 as shown in the flowchart of FIG. It is equipped with software.

Next, the alcohol concentration setting operation will be explained with reference to the flowchart shown in FIG.

First, step 1 (denoted as 81 in the figure. The same applies hereinafter).

), it is determined whether or not the alcohol sensor 9 is abnormal, for example, based on whether the output voltage value of the alcohol sensor 9 is within a permissible range. If it is determined to be normal, step 18
The detection value detected by the alcohol sensor 9 is selected, and after the engine is started, the fuel supply amount is corrected using the alcohol concentration correction coefficient based on the detection value, and the fuel supply amount T is adjusted.
Configure i. Further, when it is determined that there is an abnormality, the process proceeds to step 2.

In step 2, it is determined whether the alcohol concentration has already been calibrated (estimated) based on the air-fuel ratio detected by the oxygen sensor 6 and the calibration value (estimated value by the first concentration estimation means) has been selected. .

If it has not been selected yet, proceed to step 3.
If the selection has already been made, step 3 is skipped and the process proceeds to steps 4 and 5.

In step 3, a preset fixed value (for example, alcohol concentration 50%) is selected. Here, the fixed value is a rich limit at which engine combustion is stable for gasoline, and a lean limit at which engine combustion is stable for alcohol fuel, so it is a value at which engine combustion is approximately stable regardless of the alcohol concentration.

In steps 4 and 5, an abnormality display of the alcohol sensor 9 and a display indicating that methanol replenishment is prohibited are displayed on the display device 13, respectively, to inform the occupant that only gasoline fuel should be supplied.

In step 6, it is determined whether the starter switch IO is ON or not, and if it is ON, the engine is started (during cranking).
If it is determined that it is not ON, the process proceeds to step 7, and if it is not ON, the process proceeds to step 10.

In step 7, it is determined whether the remaining amount of fuel in the fuel tank has increased based on the output from the remaining amount sensor 11, and if it has increased, it is determined that refueling has been performed and the process proceeds to step 8. Moreover, if it does not increase, it is determined that there is no refueling.

In step 8, a refueling determination flag is set to 1.

In step 9, the alcohol concentration that changes due to refueling is estimated, and the estimated value (estimated value by the second concentration estimating means)
Calculate. This calculation is calculated from the remaining amount of fuel before refueling and the amount of refueling fuel based on the detection output of the remaining amount sensor 11. In other words, if the fuel to be refueled is specified, for example gasoline, the alcohol concentration of the refueled fuel can be calculated as O. Therefore, if the remaining amount of fuel is X, the concentration of the remaining fuel is M, and the amount of refueling is Y, then after refueling, Estimated alcohol concentration of fuel A
is determined by the following formula.

The remaining amount is 107. For example, if the refueling amount is 301, if the air-fuel ratio calibration has not been performed even once, the concentration of the remaining fuel will be 50% of the fixed value, so it will be as follows. Incidentally, if calibration based on the air-fuel ratio has been performed, the concentration M of the remaining fuel is calculated using the calibration value at that time.

Thereafter, when the starter switch 10 is turned off, the process proceeds to step io.

In step 10, if it is determined in step 7 that there is no refueling, the refueling determination flag is 0, so the process goes to step 11, and if it is determined in step 7 that there is refueling, the refueling determination flag is I. Since there is, proceed to step 14.

In step II, if a calibration value was selected in step 2, it is determined as YES (calibration completed), and the process proceeds to step 12, where the calibration value calculated from the air-fuel ratio is selected, and the alcohol based on this calibration value is Density correction coefficient AL
The fuel supply amount is corrected by C. If no selection is made in step 2 but a fixed value is selected in step 3, the determination is No (calibration is not completed) and the process proceeds to step 13.

In step I3, the alcohol concentration is calibrated (estimated) based on the air-fuel ratio detection signal from the oxygen sensor 6. Calibration of the alcohol concentration based on the air-fuel ratio reduces the alcohol concentration by a predetermined amount when the air-fuel ratio is rich, and increases the alcohol concentration by a predetermined amount when the air-fuel ratio is lean. Then, when a predetermined period of time has elapsed, the calibration is considered to be completed and step 1
If the determination in step 1 is YES, the alcohol concentration at that time is set as the final calibration value, and the calibration value is selected by switching from the fixed value selected up to that point. Therefore, until the calibration is completed, correction is performed using the alcohol concentration correction coefficient based on the fixed value, and once the calibration is completed, the fuel supply amount is corrected using the alcohol concentration correction coefficient ALC based on the calibration value.

If YES (refueling determination flag = 1) is determined in step 10 and the process proceeds to step 14, it is determined whether the estimated value calculated in step 9 matches the currently selected fixed value or calibration value. If they match, proceed to step 15; if not, proceed to step 1.
Proceed to step 7.

In step 17, the currently selected alcohol concentration value is newly set so as to approach the estimated value step by step. When this operation is repeated and the alcohol concentration value matches the estimated value, the determination in step 14 becomes YES and the process proceeds to step 15. Here, the reason why the current selected value is gradually brought closer to the estimated value is that immediately after refueling, fuel with the alcohol concentration before refueling still remains, and the alcohol concentration does not change immediately.

In step 15, the refueling determination flag is set to O, and the process proceeds to step 16.

In step 16, the estimated value calculated in step 9 after refueling is selected. Thereafter, a new calibration is performed based on the air-fuel ratio detected from the output signal from the oxygen sensor 6, and when the calibration is completed, the calibrated value is used as the alcohol concentration and the fuel supply amount is corrected based on this.

As mentioned above, when the alcohol sensor 9 is abnormal,
If the concentration has already been calibrated using the air-fuel ratio,
The fuel supply amount is corrected using the calibration value at that time without performing new calibration until the next refueling, and when it is determined that refueling is required, the alcohol concentration of the fuel after refueling is estimated and the estimated value is used. Since the calibration value is gradually brought closer, there is no longer a period in which the engine is operated with a fixed value as in the past, and the correction is made in a state close to the actual alcohol concentration value, improving engine startability and combustion stability. improves.

Note that when calibration has not been performed, regardless of the presence or absence of refueling, the initial value is set to a fixed value as in the past, and after the calibration is completed, the fuel supply amount is corrected by switching to the calibrated value.

<Effects of the Invention> As explained above, according to the present invention, the fuel to be supplied when the alcohol concentration detection means is abnormal is designated as a specific fuel, and the presence or absence of refueling is determined. When starting the engine, the concentration of the fuel after refueling is estimated and the fuel supply amount is corrected using this estimated value. The alcohol concentration can be set to a value close to the actual alcohol concentration, improving the stability of engine operation, preventing deterioration of emissions, and improving the controllability of the air-fuel ratio.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a control flowchart showing the alcohol concentration setting operation of the same embodiment. 1... Control unit 2... Air flow meter 3... Crank angle sensor 4... Engine 6... Oxygen sensor 9... Alcohol sensor
1゜...Starter switch 11...Remaining amount sensor 12...Fuel injection valve 13...Display device patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] Alcohol concentration detection means for detecting the alcohol concentration in fuel; fuel supply amount setting means for correcting and setting the fuel supply amount based on the detected value of the alcohol concentration detection means; and presence or absence of abnormality in the alcohol concentration detection means. an abnormality determination means for determining the air-fuel ratio of the engine; an air-fuel ratio detection means for detecting the air-fuel ratio of the engine; and an alcohol concentration is estimated based on the air-fuel ratio detected by the air-fuel ratio detection means when the alcohol concentration detection means is determined to be abnormal. A first concentration estimating means, an estimation completion determining means for determining whether or not the estimation operation by the first concentration estimating means has been completed, an engine start detecting means for detecting engine start, and an alcohol concentration detecting means that detects an abnormality. A refueling fuel instructing means for instructing the refueling fuel to be a specific fuel when the determination is made, a fuel amount detecting means for detecting the amount of fuel in the fuel tank, and refueling of fuel based on the detection output of the fuel amount detecting means. a refueling determining means for determining whether refueling has been performed, and a fuel alcohol concentration after refueling is estimated based on the remaining amount of fuel and the refueling amount from the detection output of the fuel amount detecting means when it is determined that refueling has been performed. and a second concentration estimating means that determines that the alcohol concentration value input to the fuel supply amount setting means is determined to be abnormal when the alcohol concentration detecting means determines that the alcohol concentration value is input to the fuel supply amount setting means at the time of starting the engine immediately after refueling is determined by the refueling determining means. When it is determined that the estimation operation of the concentration estimating means has been completed, the estimated value of the first concentration estimating means is used as the initial value, and after a predetermined period of time, the estimated value is switched to the estimated value of the second concentration estimating means, and it is determined that the alcohol concentration detecting means is abnormal. and concentration switching means for switching to the estimated value of the second concentration estimating means after a predetermined period of time with a preset fixed value as the initial value when it is determined that the estimating operation of the first concentration estimating means has not been completed. What is claimed is: 1. A fuel supply device for an internal combustion engine, characterized by comprising: