JP2001132522A - Prohibiting method for fuel control abnormality determination for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that a fuel amount control abnormality is erroneously detected because of an improper correction of the fuel amount control by atmospheric pressure, in the case of running in a place under the atmospheric pressure different from a learned atmospheric pressure. SOLUTION: In the fuel amount control, an opening degree of a throttle valve 2 disposed to an air intake system 1 of an internal combustion engine, pressure in the air intake system 1, and an engine speed are detected, the atmospheric pressure is learned based on pressure detected when at least the throttle valve 2 is fully opened, and the fuel amount is controlled based on the pressure in the air intake system 1 that is corrected by at least the learned atmospheric pressure and the engine speed. The pressure in the air intake system 1 is predicted based in the detected engine speed and the opening of the throttle valve 2, the predicted pressure is corrected by the learned atmospheric pressure, and when a difference between the corrected pressure and an actual pressure of the intake system 1 exceeds a preset specified value. A determination of the fuel amount abnormality control is prohibited by determining that the learning of the atmospheric pressure is abnormal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a fuel amount based on an engine speed and an intake system pressure.
The present invention relates to a fuel control abnormality determination prohibition method for an internal combustion engine that prohibits abnormality determination in fuel control when the atmospheric pressure is erroneously learned.

[0002]

2. Description of the Related Art Heretofore, there has been known an internal combustion engine whose fuel injection amount is controlled by an electronic control unit, using a pressure sensor for detecting an intake pipe pressure to control the fuel injection amount. That is, the atmospheric pressure and the intake pipe pressure are detected by the pressure sensor, and the fuel injection amount is determined based on the intake pipe pressure and the engine speed corrected based on the detected atmospheric pressure. In this case, the intake pipe pressure obtained when the intake pipe pressure when the ignition switch is turned on and the intake pipe pressure when the throttle valve is fully opened during running is corrected by the engine speed at that time is learned as atmospheric pressure. Things.

Therefore, for example, when the ignition switch is turned on on a flat ground, the atmospheric pressure on the flat ground is detected and stored (learned) based on the output signal from the pressure sensor.
After that, when the vehicle travels to high altitude and the throttle valve is fully opened, the atmospheric pressure at the traveling location, that is, high altitude is detected based on the output signal of the pressure sensor at the time when the throttle is fully opened, and stored until then. The updated atmospheric pressure is updated with the newly detected atmospheric pressure.

The change in the atmospheric pressure between the highland and the flatland is detected, the intake pipe pressure is corrected based on the detected atmospheric pressure, and the fuel injection amount is determined based on the corrected intake pipe pressure and the engine speed. What is controlled is disclosed in JP-A-6-129307.
No., published in Japanese Unexamined Patent Publication No.

[0005]

However, when the vehicle is started at a high altitude, the atmospheric pressure at the high altitude is learned at the time of the start, and then the vehicle goes down to a flat surface without fully opening the throttle valve, the running at the high ground is difficult. The intake pipe pressure is corrected based on the atmospheric pressure learned in step (1). However, since the atmospheric pressure learned at a high altitude is not the atmospheric pressure at a flat ground, if the intake pipe pressure is corrected, it cannot be correctly corrected. Therefore, when the fuel amount is calculated based on the intake pipe pressure corrected for the atmospheric pressure, and the feedback control is performed so that the air-fuel ratio becomes close to the stoichiometric air-fuel ratio, the correction coefficient at the time of the calculation, for example, the rotation feedback correction coefficient becomes the upper limit or lower limit. Retained states may occur. As described above, when the correction coefficient at the time of calculation becomes an abnormal value, there is a possibility that it is determined that the function for controlling the fuel is abnormal due to such a change in the correction coefficient. In other words, the fuel control system itself may be normal, but may be erroneously determined to be abnormal.

An object of the present invention is to solve such a problem.

[0007]

In order to achieve the above object, the present invention takes the following measures. That is, the fuel control abnormality determination prohibition method for an internal combustion engine according to the present invention learns the atmospheric pressure, corrects the pressure of the intake system with the learned atmospheric pressure, and uses the fuel pressure at least based on the corrected atmospheric pressure and the engine speed. In controlling the amount, the pressure of the intake system is predicted based on the opening degree of the throttle valve and the engine speed, and the predicted pressure is corrected to the atmospheric pressure,
When the difference between the predicted pressure corrected by the atmospheric pressure and the actual pressure of the intake system exceeds a predetermined value, the learned abnormality of the atmospheric pressure is determined, and the abnormality determination when performing the fuel control is prohibited.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to an opening degree of a throttle valve provided in an intake system of an internal combustion engine, a pressure of the intake system,
The engine speed is detected, and the atmospheric pressure is learned based on at least the pressure detected when the throttle valve is fully open, and the fuel is determined based on at least the intake system pressure and the engine speed corrected based on the learned atmospheric pressure. Control the amount, predicting the pressure of the intake system based on the detected engine speed and the opening of the throttle valve, correcting the predicted pressure with the learned atmospheric pressure, and correcting the corrected pressure and the intake system. Wherein the difference between the actual pressure and the actual pressure exceeds a predetermined value set in advance, the learning of the atmospheric pressure is determined to be abnormal, and the abnormality determination when controlling the fuel amount is prohibited. This is a control abnormality determination prohibition method.

With such a configuration, an abnormality occurring in the control of the fuel amount is determined when learning of the atmospheric pressure is normal. That is, the difference between the actual intake system pressure and the predicted pressure corrected based on the learned atmospheric pressure, which is predicted based on the engine speed and the opening of the throttle valve, is the pressure predicted based on the learned atmospheric pressure. Is caused by correcting. At this time, if the learned atmospheric pressure is normal, the difference is small, and if it is abnormal, the difference is large.
When the difference exceeds a predetermined value set in advance, the learned atmospheric pressure is abnormal, and the control of the fuel amount becomes abnormal due to the learned abnormality of the atmospheric pressure. Ban. Therefore, when the control of the fuel amount is normal, it is possible to reliably prevent erroneous determination of abnormality.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. The engine whose one-cylinder structure is schematically shown in FIG. 1 is a four-cylinder engine for an automobile, and an intake system 1 of the engine is provided with a throttle valve 2 that opens and closes in response to an accelerator pedal (not shown). The surge tank 3 is provided on the downstream side, and the intake air from the surge tank 3 is sucked into the cylinder via the intake valve 37. The intake system 1 is provided with a bypass passage 1a which is a detour bypassing the throttle valve 2. The bypass passage 1a has a flow control valve (hereinafter, referred to as a flow control valve) for controlling the amount of air passing through the bypass passage 1a. An "ISC valve" is abbreviated.) 1b is provided. The ISC valve 1b performs control at the time of executing idle rotation control (hereinafter, abbreviated as "ISC") for correcting the intake air amount so that the engine speed NE at least in the idle operation state becomes the idle target speed. Opening control is performed when a load acting on the engine such as an air conditioner or a headlight is activated. A fuel injection valve 5 is further provided near an end of the intake manifold 4 of the intake system 1 communicating with the surge tank 3 on the cylinder head side. The fuel injection valve 5 is controlled by an electronic control unit 6. ing. Also, the exhaust system 20
The O ₂ sensor 21 for measuring the oxygen concentration in the exhaust gas discharged from the combustion chamber via the exhaust valve 36 is provided with a three-way catalyst 2 disposed in a pipe to a muffler (not shown).
2 upstream.

The electronic control unit 6 is mainly composed of a microcomputer system including a central processing unit 7, a storage device 8, an input interface 9, and an output interface 11. The input interface 9 receives an intake pressure signal a output from an intake pressure sensor 13 for detecting the pressure (intake pipe pressure) in the surge tank 3 and a rotational speed sensor 14 for detecting an engine rotational speed NE. The output rotation speed signal b, the crank angle signal m and the cylinder discrimination signal n output from the cam position sensor 25, the throttle opening signal output from the throttle sensor 16a corresponding to the opening of the throttle valve 2, the throttle valve 2, an IDL signal d output from the idle switch 16 for detecting the open / close state of the engine ₂ , a water temperature signal e output from the water temperature sensor 17 for detecting the engine coolant temperature, and an output from the O ₂ sensor 21 described above. The voltage signal h and the like are input. On the other hand, from the output interface 11, a drive pulse INJ, which is a fuel injection signal f, to the fuel injection valve 5,
, An ignition signal g is output.

The electronic control unit 6 uses the intake pressure signal a output from the intake pressure sensor 13 and the rotational speed signal b output from the rotational speed sensor 14 as main information and is determined according to the operating state of the engine. The basic injection time, that is, the basic injection amount TAUB is corrected with various correction coefficients to determine the final injection time, that is, the fuel injection amount TAU, which is the fuel injection valve opening time, and the fuel injection valve 5 is controlled based on the determined time. In addition, a program for injecting the fuel fuel amount TAU according to the operating state of the engine from the fuel injection valve 5 to the intake system 1 is incorporated. Also, in this program, when an ignition switch (not shown) is turned on before starting, the atmospheric pressure is detected based on the intake pressure signal a output by the intake pressure sensor 13 at that time, and the detected atmospheric pressure is detected. This is stored in the storage device 8. Further, when the throttle valve 2 is fully opened during traveling, the intake pipe pressure PMTP at that time is corrected based on the engine speed NE and stored in the storage device 8. When the throttle valve 2 is fully opened during driving, the stored atmospheric pressure, that is, the learned atmospheric pressure reading is replaced with the stored atmospheric pressure reading at the time of full opening. And save as the atmospheric pressure reading.

The electronic control unit 6 includes an opening of the throttle valve 2, a pressure of the intake system 1, and an engine speed N.
E is detected, and the atmospheric pressure is learned based on at least the pressure detected when the throttle valve 2 is fully opened. Based on at least the pressure of the intake system 1 and the engine speed NE corrected based on the learned atmospheric pressure. The controller controls the fuel amount and predicts the pressure of the intake system 1 based on the detected engine speed NE and the opening degree of the throttle valve 2.
The predicted pressure is corrected by the learned atmospheric pressure, and when the difference between the corrected pressure and the actual pressure of the intake system exceeds a predetermined value set in advance, it is determined that the learning of the atmospheric pressure is abnormal and the fuel amount is determined. A program is built in to prohibit abnormality determination during control.

Next, a schematic procedure of the fuel system abnormality determination prohibition control program will be described with reference to FIGS. In order to determine whether or not the atmospheric pressure detection, that is, the learning has been performed normally, the intake pipe pressure is predicted based on the throttle opening TA and the engine speed NE. This intake pipe pressure prediction routine is performed, for example, every 8 msec. The prediction of the intake pipe pressure is basically made based on the throttle opening TA and the engine speed NE. In consideration of the fact that the intake pipe pressure slightly changes due to the opening of the ISC valve 1b. Based on the opening of the ISC valve 1b, the intake pipe pressure predicted from the throttle opening TA and the engine speed NE is corrected so as to more accurately predict the intake pipe pressure.

First, in step S1, a two-dimensional throttle opening degree map is searched based on the throttle opening degree TA and the engine speed NE to determine a basic intake pipe pressure predicted value TAPMB based on the throttle opening degree TA. This throttle opening two-dimensional map is based on a representative value of the throttle opening TA and the engine speed NE, and a basic predicted intake pipe pressure value TAPMB.
Is set, and when the value is other than the representative value, the value is obtained by performing an interpolation calculation.

In step S2, the opening degree correction two-dimensionally based on the throttle opening degree TA and the engine speed NE when the learning value DLRN of the opening degree of the ISC valve 1b is added to the opening degree 50% of the ISC valve 1b. A map is retrieved to determine an intake pipe pressure ISC opening basic predicted value ISCPMB. The learning value DLRN is a learning value in the ISC, and the ISC valve 1
It is updated to absorb variations in characteristics and changes with time for each b. In step S3, the intake pressure sensor 1
3 depends on the actual ISC valve opening when abnormal.
An interpolation coefficient map for SC valve opening correction is searched to find an interpolation coefficient KISCPM. In each of these maps, a representative value is also set, and the other values are obtained by performing an interpolation calculation. Next, in step S4, the intake pipe pressure ISC opening predicted value ISCPM is calculated by multiplying the intake pipe pressure ISC opening basic predicted value ISCPMB obtained in step S2 by the interpolation coefficient KISCPM obtained in step S3.

In step S5, the intake pipe pressure basic predicted value TAPMB and the intake pipe pressure ISC open predicted value ISPPM are added, and the sum is multiplied by an atmospheric pressure correction coefficient KPA to correct the atmospheric pressure corrected tap air predicted value TAPPM. Is calculated.
The atmospheric pressure correction coefficient KPA is indicated by, for example, the ratio of the atmospheric pressure stored by learning to the standard atmospheric pressure on flat ground. In step S6, the calculation by the following formula this 8m seconds after the intake pipe pressure estimated value PMFs _n. PMFS _n = PMFS _n-1 + TCON _n × (TAPM _n
−PMFS _n−1 ) Here, TCON _n is a charge delay time constant of the intake system 1 and is obtained by searching a map set by the engine speed NE and the throttle opening TA. The current one and n-1 indicate the one that was previously calculated (retrieved). This predicted intake pipe pressure PMFS after 8 ms is the same as the intake pipe pressure predicted value TAPM calculated this time, if the intake pipe pressure predicted value PMFS _n-1 calculated last time is the same as the intake pipe pressure predicted value TAPM calculated this time. The predicted pipe pressure value PMFS _n-1 is set as the predicted intake pipe pressure value PMFS _n after 8 msec this time.

In step S7, the time until the next intake is calculated from the engine speed NE, and the final intake pipe pressure predicted value PMFFS is calculated from the intake pipe pressure predicted value PMFS after 8 ms.
Is calculated. Next, a procedure for verifying whether the learned atmospheric pressure is normal will be described. In the case of this four-cylinder engine, for example, four times in two revolutions, that is, one for one cylinder
This routine is performed once.

In FIG. 3, first, at step S11, the intake pipe pressure final predicted value PMFFS and the intake pressure sensor 1
3, the absolute value of the difference from the actual intake pipe pressure PMTP detected based on the intake pressure signal a output from
PMPA. In step S12, the pressure deviation DPM
It is determined whether PA is below the abnormality determination level KDPMPA. In step S13, it is determined that the learned atmospheric pressure, that is, the atmospheric pressure read value is abnormal, and the abnormality determination in the fuel control is prohibited. In step S14,
Assuming that the atmospheric pressure read value is normal, an abnormality determination in fuel control is executed.

In such a configuration, a case will be described in which the atmospheric pressure is learned at a high altitude, and thereafter, the vehicle moves to a flat ground without learning the atmospheric pressure. In this case, the atmospheric pressure correction coefficient KPA is smaller than the atmospheric pressure correction coefficient KPA on flat ground, reflecting the learning at high altitude. First, an intake pipe pressure final predicted value PMFFS is calculated in order to determine an abnormality in the atmospheric pressure read value. This intake pipe pressure final predicted value PM
The FFS is a prediction based on the throttle opening TA, the engine speed NE, and the atmospheric pressure correction coefficient KPA by executing steps S1 to S7.
Since the calculated intake pipe pressure final predicted value PMFFS has been corrected by the atmospheric pressure correction coefficient KPA in step S5, it reflects the atmospheric pressure read value.

Next, the calculated intake pipe pressure final predicted value PM
By comparing the FFS with the intake pipe pressure PMTP actually detected by the intake pressure sensor 13 at this time, it is verified whether the atmospheric pressure reading is normal or abnormal.
In this verification, first, step S1 is executed, and the pressure deviation D
It is determined whether PMPA is below the abnormality determination level KDPMPA. Since the atmospheric pressure reading is learned at a high altitude, in this case, the atmospheric pressure corrected intake pipe pressure final predicted value PMFFS is the actually measured intake pipe pressure P.
MTP significantly reduced. Therefore, the pressure deviation DPMPA greatly exceeds the abnormality determination level KDPMPA. Therefore, the program proceeds from step S12 to S13, and determines that the atmospheric pressure reading is abnormal, and prohibits the abnormality determination in the fuel control.

As described above, since the atmospheric pressure correction based on the stored atmospheric pressure reading does not function properly,
When the calculated fuel injection amount TAU is not normal, it is possible to reliably prevent erroneous determination that an abnormality has occurred in fuel control based on the abnormality of the fuel injection amount TAU. On the other hand, if the atmospheric pressure reading is normal,
The atmospheric pressure correction coefficient KPA becomes a value close to 1. Therefore, the intake pipe pressure final predicted value PMFFS and the actually measured intake pipe pressure PMTP are approximate values, and the pressure deviation DPM
PA becomes a small value, and falls below the abnormality determination level KDPMPA. Thereby, it is determined that the atmospheric pressure reading is normal. In this case, for example, when the rotation feedback correction coefficient is held at the upper limit or the lower limit, it is determined that there is an abnormality in the control of the fuel amount and the abnormality of the fuel control is detected. Things. As described above, since the abnormality of the fuel control is detected only when the atmospheric pressure reading is determined to be normal, the abnormality of the fuel control can be accurately detected, and the execution of the incorrect fuel control is prevented. can do.

The present invention is not limited to the embodiment described above. In addition, the configuration of each unit is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0024]

As described above, according to the present invention, the prediction is made based on the actual intake system pressure, the engine speed and the opening of the throttle valve, and corrected with the learned atmospheric pressure. Since the difference from the pressure is generated by correcting the predicted pressure with the learned atmospheric pressure, if the difference is small, it can be determined that the learned atmospheric pressure is normal. Conversely, if the difference is large, it can be determined that there is an abnormality. When the difference exceeds a predetermined value set in advance, the learned atmospheric pressure is abnormal, and the control of the fuel amount becomes abnormal due to the learned abnormality of the atmospheric pressure. Is prohibited, and when the control of the fuel amount is normal, it can be surely prevented from being erroneously determined to be abnormal.

[Brief description of the drawings]

FIG. 1 is a schematic structural explanatory view showing one embodiment of the present invention.

FIG. 2 is a flowchart showing an outline of a control procedure of the embodiment.

FIG. 3 is a flowchart showing an outline of a control procedure of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Intake system 1b ... Flow control valve 2 ... Throttle valve 6 ... Electronic control device 7 ... Central processing unit 8 ... Storage device 9 ... Input interface 11 ... Output interface 13 ... Intake pressure sensor 16a ... Throttle sensor

Claims (1)

[Claims] An opening degree of a throttle valve provided in an intake system of an internal combustion engine, a pressure of the intake system, and an engine speed are detected, and at least based on the pressure detected when the throttle valve is fully open. Atmospheric pressure is learned, and the fuel amount is controlled based on the intake system pressure and the engine speed corrected by at least the learned atmospheric pressure, and based on the detected engine speed and the opening degree of the throttle valve. The intake system pressure is predicted, and the predicted pressure is corrected by the learned atmospheric pressure.If the difference between the corrected pressure and the actual intake system pressure exceeds a predetermined value, learning of the atmospheric pressure is abnormal. A fuel control abnormality determination prohibition method for an internal combustion engine, comprising: prohibiting abnormality determination when controlling the fuel amount by determining that there is a fuel control.