JP2002309992A - Atmospheric pressure learning device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an atmospheric pressure learning device for an internal combustion engine capable of accurately performing atmospheric pressure learning even at the change of an engine operating state. SOLUTION: The actual intake air quantity eklsm of an intake passage is detected. On the basis of engine speed ne, throttle opening ta and valve timing vt, a basic intake air quantity eklta is computed referring to an intake air quantity map. The reference intake air quantity eklcrt, considering the change of an engine operating state, is computed on the basis of the basic intake air quantity eklta. When the difference tdlkltn obtained by subtracting the actual intake air quantity eklsm from the reference intake air quantity eklcrt is less than -α% and the operating state is not in a back flow generating operating state, a prescribed value is added to the present atmospheric pressure correction value to update the atmospheric pressure correction value ekpa. When the difference tdlkltn is larger than α%, the prescribed value is subtracted from the present atmospheric pressure correction value to update the atmospheric pressure correction value ekpa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for learning the atmospheric pressure of an internal combustion engine which learns the atmospheric pressure based on an intake air amount ratio of the internal combustion engine without using an atmospheric pressure sensor.

[0002]

2. Description of the Related Art In recent years, an atmospheric pressure learning correction amount used for fuel injection control (air-fuel ratio control) of an engine is obtained with an inexpensive configuration without using an atmospheric pressure sensor. No. pp. 147-64.
This uses an intake air amount map at a reference atmospheric pressure set according to the engine operating state including the engine speed and the throttle opening, and uses the intake air amount at the reference atmospheric pressure according to the engine operating state at that time. Find the quantity. Then, an atmospheric pressure correction value is obtained by comparing the intake air amount at the reference atmospheric pressure with the intake air amount actually measured by the air flow meter.

The flow of intake air in the intake passage is affected by the pulsation of the intake air of the engine. When the throttle opening increases, the pulsation of the intake air increases in the low rotational speed range of the engine. , A backflow of intake air occurs. When such a backflow occurs, the airflow meter also measures the amount of the backflowed air in principle, so that the airflow is excessively measured with respect to the amount of the air actually sucked. For this reason, in the engine operating state where backflow occurs,
The amount of intake air measured by the air flow meter includes an error due to the backflow, so that an accurate atmospheric pressure correction value cannot be calculated. In order to eliminate such an error due to the backflow, when calculating the atmospheric pressure correction value, the maximum intake air amount at the reference atmospheric pressure is obtained, and this maximum intake air amount is used as the upper limit guard value, and the actual value measured by an air flow meter is used. The intake air amount is limited to the upper limit guard value or less.

The intake air amount map is basically set based on the actual intake air amount measured by an air flow meter in a stable state of the throttle opening and the engine rotation speed at a reference atmospheric pressure. In the engine operating state where the backflow occurs, a value is set for the upper limit guard value in consideration of a correction value in the air-fuel ratio control.

[0005]

Therefore, according to the technique described in the above publication, when the actual operating air amount is measured and the engine operating state is stable, the actual intake air amount is not affected by the delay of the intake air. The difference between the reference intake air amount and the actual intake air amount is due to the atmospheric pressure difference. Therefore, in a stable state of the engine operation state, the atmospheric pressure learning can be accurately performed by comparing the reference intake air amount and the actual intake air amount.

However, when the engine operating state changes, such as when the throttle opening changes or the engine speed changes, the intake air changes later than the engine operating state changes. Includes the effects of delay. Therefore, the difference between the reference intake air amount and the actual intake air amount based on the engine operation state at that time includes the influence of the delay of the intake air in addition to the atmospheric pressure difference, and the accurate atmospheric pressure correction value is calculated. There is a problem that learning is not possible and learning is mistaken.

Further, when the actual intake air amount measured by the air flow meter has a large value in an engine operating state in which a backflow occurs, the actual intake air amount is limited to the upper limit guard value. However, in the engine operating state where the backflow occurs, the reference intake air amount referred to the intake air amount map is set to a value that takes into account the correction value of the air-fuel ratio control. The value may be larger than the intake air amount. In this case, there is a problem that erroneous learning is performed in a direction to increase the atmospheric pressure correction value.

The present invention has been made in view of the above circumstances, and has as its object to provide an atmospheric pressure learning device for an internal combustion engine that can accurately perform atmospheric pressure learning even when the engine operating state changes. Is to do.

Another object of the present invention is to provide an atmospheric pressure learning device for an internal combustion engine which can prevent erroneous learning of atmospheric pressure learning in a backflow generating operation state in which backflow of intake air occurs.

Another object of the present invention is to provide an atmospheric pressure learning device for an internal combustion engine that can accurately perform atmospheric pressure learning even in a backflow generating operation state in which backflow of intake air occurs.

[0011]

The means for achieving the above object and the effects thereof will be described below. According to the first aspect of the present invention, an air flow meter for measuring an actual intake air amount passing through an intake passage of an internal combustion engine and an engine operating state including an opening degree of a throttle valve provided in the intake passage and an engine rotation speed are provided. Calculating a basic intake air amount at a reference atmospheric pressure based on the reference intake air amount, and calculating a reference intake air amount in consideration of the change in the engine operating state based on the basic intake air amount; and Learning means for performing atmospheric pressure learning by comparing the actual intake air amount with the actual intake air amount.

According to the configuration of the first aspect, the basic intake air amount is stable in the stable state of the engine operating state, and the basic intake air amount becomes the reference intake air amount. Therefore, the difference between the reference intake air amount calculated based on the engine operating state and the actual intake air amount is due to the atmospheric pressure difference. Therefore, in a stable state of the engine operating state, the atmospheric pressure learning can be accurately performed by comparing the reference intake air amount and the actual intake air amount. Also, when the engine operating state changes, such as when the throttle opening changes or the engine speed changes, the actual intake air amount changes with a delay with respect to the change in the engine operating state. At this time, since the reference intake air amount is calculated based on the basic intake air amount in consideration of a change in the engine operating state, the reference intake air amount takes into account the delay of the intake air. Therefore, both the reference intake air amount and the actual intake air amount include the influence of the delay of the intake air, and the difference between the reference intake air amount and the actual intake air amount depends on the atmospheric pressure difference. Therefore, even when the engine operating state changes, the atmospheric pressure learning can be accurately performed by comparing the reference intake air amount and the actual intake air amount.

According to a second aspect of the present invention, there is provided an air flow meter for measuring an actual intake air amount passing through an intake passage of an internal combustion engine, and an engine including an opening degree of a throttle valve provided in the intake passage and an engine rotation speed. Calculating means for calculating a reference intake air amount based on a basic intake air amount at a reference atmospheric pressure calculated according to an operation state; and determining whether the engine operation state is a backflow generation operation state in which a backflow of intake air occurs. Determining means for determining, learning means for performing atmospheric pressure learning by comparing the reference intake air amount and the actual intake air amount,
When the engine operating state is determined to be the backflow generating operating state, when the actual intake air amount is greater than the reference intake air amount, a prohibition unit that prohibits an increase and update of the atmospheric pressure correction value by the learning unit, It is characterized by having.

According to the second aspect of the present invention, when the determining means determines that the current is in the reverse flow generating operation state, the increasing means of the atmospheric pressure correction value is prohibited by the prohibiting means. Is prevented.

According to a third aspect of the present invention, there is provided an air flow meter for measuring an actual intake air amount passing through an intake passage of an internal combustion engine, and an engine including an opening degree of a throttle valve provided in the intake passage and an engine rotation speed. Calculating means for calculating a reference intake air amount based on a basic intake air amount at a reference atmospheric pressure calculated according to an operation state; and comparing the reference intake air amount with the actual intake air amount to obtain an atmospheric pressure. Learning means for learning, comprising: an atmospheric pressure learning device for an internal combustion engine, wherein the calculating means is set to an actual intake air amount measured by the air flow meter in an arbitrary engine operating state at the reference atmospheric pressure. Storage means for storing the calculated air amount data, wherein the calculating means calculates the basic intake air amount by referring to the air amount data based on the engine operating state at that time. To.

According to the configuration of the third aspect, in the backflow generating operation state, the amount of backflow is included in the actual intake air amount measured by the air flow meter. Since the air amount data for calculating the reference intake air amount is set based on the actual intake air amount measured at the reference atmospheric pressure in an arbitrary engine operating state, the air amount data includes the backflow in the reverse flow generating operation state. . Therefore, even if the engine operation state is the reverse flow generation operation state, the difference between the reference intake air amount and the actual intake air amount is caused by the atmospheric pressure difference, and the reference intake air amount and the actual intake air amount are compared. Thus, the atmospheric pressure learning can be performed with high accuracy.

According to a fourth aspect of the present invention, in the atmospheric pressure learning device for an internal combustion engine according to any one of the second and third aspects, the calculating means operates the engine based on the basic intake air amount. It is characterized in that a reference intake air amount is calculated in consideration of a change in the state.

According to the configuration of the fourth aspect, when the engine operating state changes, the actual intake air amount changes with a delay with respect to the engine operating state change, but the reference intake air amount changes to the basic intake air amount. Therefore, the reference intake air amount is calculated in consideration of the delay of the intake air. Therefore, both the reference intake air amount and the actual intake air amount include the influence of the delay of the intake air, and the difference between the reference intake air amount and the actual intake air amount depends on the atmospheric pressure difference. Therefore, by comparing the reference intake air amount and the actual intake air amount, the atmospheric pressure learning can be accurately performed even when the engine operating state changes.

According to a fifth aspect of the present invention, in the atmospheric pressure learning device for an internal combustion engine according to any one of the first to fourth aspects,
The learning means performs atmospheric pressure learning when a difference between the reference intake air amount and the actual intake air amount is equal to or greater than a predetermined value.

According to the configuration of claim 5, when the difference between the calculated reference intake air amount and the actual intake air amount is equal to or more than a predetermined value,
Since the atmospheric pressure learning is performed based on the reference intake air amount and the actual intake air amount, the opportunity for the atmospheric pressure learning does not become excessive, and the appropriate atmospheric pressure correction value is obtained while securing the opportunity for the atmospheric pressure learning. Obtainable.

[0021]

(First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a schematic configuration of an engine system according to this embodiment. The engine 1 includes a plurality of cylinders 2, and a piston 3 provided for each cylinder 2 is connected to a crankshaft 1 a as an output shaft, and can move up and down in each cylinder 2. I have. The upper side of the piston 3 in each cylinder 2 forms a combustion chamber 4.

The ignition plugs 5 provided corresponding to the respective combustion chambers 4 ignite the air-fuel mixture introduced into the combustion chambers 4. Each of the intake port 6a and the exhaust port 7a provided corresponding to each combustion chamber 4 constitutes a part of the intake passage 6 and the exhaust passage 7.

The intake valve 8 and the exhaust valve 9 provided corresponding to each combustion chamber 4 respectively have ports 6a, 7a.
Open each. Each of these valves 8, 9 operates based on the rotation of different camshafts 10, 11. The timing pulleys 12 and 13 provided at the tips of the camshafts 10 and 11 respectively correspond to the timing belt 1.
4 to the crankshaft 1a.

When the engine 1 is operating, the rotational force of the crankshaft 1a is transmitted to the respective camshafts 10 and 11 via the timing belt 14 and the respective timing pulleys 12 and 13.
Is transmitted to When the camshafts 10 and 11 rotate, the valves 8 and 9 operate. Each valve 8, 9
Can operate at a predetermined timing in synchronization with the rotation of the crankshaft 1a, that is, in synchronization with the intake stroke, the compression stroke, the explosion / expansion stroke, and the exhaust stroke according to the vertical movement of each piston 3.

An air cleaner 15 provided at the entrance of the intake passage 6 purifies the outside air taken into the passage 6. The injectors 16 provided near the respective intake ports 6a inject fuel toward the intake ports 6a.

During operation of the engine 1, outside air is taken into the intake passage 6 via the air cleaner 15. And
In the intake stroke in which the intake valve 8 opens the intake port 6a, the injector 16 of the corresponding cylinder injects fuel, so that a mixture of the injected fuel and the outside air is sucked into the combustion chamber 4. The air-fuel mixture sucked into the combustion chamber 4 is ignited by the ignition plug 5 to explode and burn. As a result, the piston 3 operates, the crankshaft 1a rotates, and an output is obtained in the engine 1.
The exhaust gas after combustion is drawn out of the combustion chamber 4 in an exhaust stroke in which the exhaust valve 9 opens the exhaust port 7a, and is discharged to the outside through the exhaust passage 7.

The throttle valve 17 provided in the intake passage 6 is opened and closed in response to the operation of an accelerator pedal (not shown). By adjusting the opening of the throttle valve 17, the effective passage area of the intake passage 6 through which the intake air passes is adjusted. A surge tank 18 provided downstream of the throttle valve 17 smoothes the pulsation of the intake air.

An intake air temperature sensor 19 provided in the vicinity of the air cleaner 15 measures the intake air temperature th and outputs a measurement signal corresponding to the measured value. A throttle sensor 20 provided in the vicinity of the throttle valve 17 measures an opening degree (throttle opening degree) ta of the throttle valve 17 and outputs a measurement signal corresponding to the measured value.

The hot wire air flow meter 21 provided upstream of the throttle valve 17 has a metal wire (heat wire) which generates heat when energized as a detection element. The air flow meter 21 applies a voltage having a magnitude corresponding to the amount of heat taken from the detection element by the intake air passing through the air flow meter 21 and the actual intake air amount ekls passing through the intake passage 6.
Output as a measurement signal corresponding to m.

On the other hand, a catalytic converter 22 provided in the middle of the exhaust passage 7 purifies exhaust gas by a built-in three-way catalyst 23. Oxygen sensor 24 provided in exhaust passage 7
Measures the oxygen concentration Ox in the exhaust gas and outputs a measurement signal corresponding to the measured value. Further, a water temperature sensor 25 provided in the engine 1 measures a temperature (cooling water temperature) thw of the cooling water for cooling the engine 1 and outputs a measurement signal corresponding to the measured value.

The distributor 26 includes the igniter 2
The high voltage output from 7 is distributed to each ignition plug 5 as an ignition signal for igniting each ignition plug 5. The operation timing of each spark plug 5 is determined by the igniter 2
7 is determined by the timing of outputting the high voltage.

The rotor (not shown) built in the distributor 26 is rotated by the camshaft 11 which rotates in synchronization with the crankshaft 1a. Rotation speed sensor 28 provided in distributor 26
Measures the rotation speed ne of the engine 1 (engine rotation speed) based on the rotation of the rotor, and outputs the measured value as a pulse signal. The cylinder discriminating sensor 29 provided in the distributor 26 measures a reference position of the crank angle (° CA) at a predetermined rate according to the rotation of the rotor, and outputs the measured value as a pulse signal. In this embodiment, the crankshaft 1a makes two rotations for a series of four strokes of the engine 1. While the crankshaft 1a makes two rotations, the rotation speed sensor 28 outputs one pulse signal every 30 ° CA. The cylinder discrimination sensor 29 is 36
A signal of one pulse is output every 0 ° CA.

In the apparatus of this embodiment, a well-known valve timing control mechanism 30 is provided at the tip of the camshaft 10 integrally with the timing pulley 12. When the valve timing control mechanism 30 operates, the lubricating oil of the engine 1 stored in the oil pan 31 is pumped up by the oil pump 32 and supplied into the mechanism 30, and the oil pressure is supplied to the oil control valve 3.
Adjust by 3. Oil control valve 33
Is controlled based on a command signal from the electronic control unit 40.

The valve timing control mechanism 30 has an outer shell formed integrally with the timing pulley 12, and has an internal rotating body (not shown) formed integrally with the camshaft 10 inside. The valve timing control mechanism 30 rotates relative to the outer rotary body and the internal rotary body by the action of hydraulic pressure supplied to the valve timing control mechanism 30 so that the camshaft 10 and the timing pulley 12 rotate relative to each other. It is configured to be. Such relative rotation between the camshaft 10 and the timing pulley 12 changes the valve timing (control advance value) vt of the intake valve 8 as a result.

On the other hand, the valve timing vt of the intake valve 8 thus changed is detected through the cam sensor 34. That is, the cam sensor 34 provided on the camshaft 10 measures an actual cam angle (rotation phase) related to the rotation of the camshaft 10 and outputs a signal corresponding to the measured value.

In the system shown in FIG. 1, the cam sensor 34, the intake air temperature sensor 19, the throttle sensor 20, the air flow meter 21, the oxygen sensor 2
4. Each sensor output of the water temperature sensor 25, the rotation speed sensor 28, and the cylinder discrimination sensor 29 is input to the electronic control unit 40.

The electronic control unit 40 is a microcomputer system, and recognizes (detects) various engine operating conditions such as the amount of intake air taken into the engine 1, the engine speed, the throttle opening and the like based on the outputs of these sensors. Then, the electronic control unit 40 executes the atmospheric pressure (altitude) learning according to the present invention, in addition to the fuel injection control, the ignition timing control, the variable control of the valve timing of the intake valve 8, and the like based on these various operating states. The electronic control unit 40 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and a backup RA.
M and so on. The ROM stores various control programs and various maps. The various maps include an intake air amount map at a reference atmospheric pressure used for atmospheric pressure learning. The CPU executes a calculation process based on the input signal. The RAM stores data in the operation and control processing of the CPU. The backup RAM is supplied with power by being directly connected to a battery (not shown),
It is used to store data (for example, various learning values) to be held even when the ignition switch is off.

The electronic control unit 4 executed in the internal combustion engine (engine) having the above hardware configuration
The engine control process of 0 will be described below. The fuel injection control basically calculates a fuel injection amount for achieving a predetermined target air-fuel ratio, that is, an injection time by the injector 16, based on an intake air amount (mass) per one rotation of the engine. Then, the injector 16 is controlled so as to inject fuel when a predetermined crank angle is reached. The intake air amount (mass) per one revolution of the engine is calculated from the intake air flow rate (mass) measured by the hot wire air flow meter 21 and the engine rotation speed obtained from the rotation speed sensor 28. In calculating the fuel injection amount, basic correction based on signals from the throttle sensor 20, the intake air temperature sensor 19, the water temperature sensor 25, etc., air-fuel ratio feedback correction based on the signal from the oxygen sensor 24, and air-fuel ratio learning Corrections and the like are added. Note that the air-fuel ratio learning correction is performed so that the median of the correction values in the air-fuel ratio feedback correction becomes the stoichiometric air-fuel ratio.

The ignition timing is controlled by the rotation speed sensor 2
8, the state of the engine 1 is comprehensively determined based on the engine speed and other signals from the sensors.
It determines the optimal ignition timing and sends an ignition signal to the igniter 27.

In the various controls described above, a correction based on the altitude, that is, the atmospheric pressure is required, and the atmospheric pressure learning for obtaining the atmospheric pressure correction value is executed. In the atmospheric pressure learning of the present embodiment also, using the intake air amount map at the reference atmospheric pressure set according to the engine operating state, the reference intake air amount at the reference atmospheric pressure according to the engine operating state at that time is used. Ask. Then, an atmospheric pressure correction value is obtained by comparing the reference intake air amount at the reference atmospheric pressure with the actual intake air amount actually measured by the air flow meter 21.

Next, the atmospheric pressure learning process executed by the electronic control unit 40 will be described with reference to the flowchart of FIG. The routine shown in the figure is executed periodically at predetermined time intervals.

When the processing shifts to the routine, the electronic control unit 40 first reads the measurement signal output from the air flow meter 21 in step 100, and based on the measurement signal, the actual intake air passing through the intake passage 6 based on the measurement signal. Quantity ek
lsm is detected. The actual intake air amount eklsm is limited to a value equal to or less than the upper limit guard value, with the maximum intake air amount at the reference atmospheric pressure as the upper limit guard value in order to remove the reverse flow in the engine operating state where the reverse flow of intake air occurs. The actual intake air amount eklsm is calculated as a load ratio (percentage) with respect to the stroke volume of the cylinder 2.

In the following step 110, the engine speed ne and the throttle opening ta are detected, and the valve timing vt is read. The engine speed ne and the throttle opening ta are obtained based on the measurement signals output from the speed sensor 28 and the throttle sensor 20, respectively, as described above.

On the other hand, the valve timing vt is obtained as follows through a separate routine (not shown) based on the measurement signals output from the rotation speed sensor 28 and the cam sensor 34.

That is, the output timing of the pulse signal of the rotation speed sensor 28 corresponds to the crank angle, and the output timing of the pulse signal of the cam sensor 34 corresponds to the cam angle. Therefore, the phase difference between the two angles, that is, the actual valve timing vt is obtained based on the difference between the two output timings.

Incidentally, the electronic control unit 40 appropriately determines a target valve timing according to the operating state of the engine 1 and performs feedback control so that the actual valve timing vt matches this target valve timing. Always running. For this reason, the electronic control unit 4
0 based on the control command of the valve timing control mechanism 30.
Is driven, and the valve timing vt is constantly changed.

In the subsequent step 120, the previous step 1
Engine speed ne and throttle opening t obtained in Step 10
Based on a and the valve timing vt, a basic intake air amount eklta is calculated with reference to an intake air amount map stored in the ROM. This intake air amount map is based on the actual intake air amount eklsm measured by the air flow meter 21 at the reference atmospheric pressure in a stable state of the engine operation state such as the engine speed ne, the throttle opening ta, and the valve timing vt. Is set. In the intake air amount map, the basic intake air amount eklta in the engine operating state in which the backflow occurs is the actual intake air amount ekls
A value that takes into account the correction value in the air-fuel ratio control is set for the upper limit guard value of m. The basic intake air amount eklta in this intake air amount map is also set as a load ratio (percentage) to the stroke volume of the cylinder 2.

In the next step 130, the previous step 12
The reference intake air amount eklcrt considering the change in the engine operating state based on the basic intake air amount eklta calculated at 0
Is calculated. As shown in FIG. 3, when the engine operating state changes, the intake air in the intake passage 6 changes with a delay with respect to the change, and the actual intake air amount eklsm includes the influence of the delay. The basic intake air amount eklta is an air amount in a stable state of the engine operating state. for that reason,
The difference between the basic intake air amount eklta and the actual intake air amount eklsm calculated based on the engine operating state at that time includes the influence of the delay of the intake air in addition to the atmospheric pressure difference. On the other hand, the reference intake air amount eklcrt calculated based on the basic intake air amount eklta in consideration of a change in the engine operation state takes into account the influence of the delay of the intake air. Therefore, both the reference intake air amount eklcrt and the actual intake air amount eklsm include the influence of the delay of the intake air, and the reference intake air amount eklcrtt
And the actual intake air amount eklsm are substantially due to the atmospheric pressure difference. Incidentally, in the present embodiment, the reference intake air amount eklcrt is calculated by the following equation (1).

[0050]

Eklcrt (i) = eklcrt (i−1) + {eklta + eklcrt (i−1)} / Δ (1) where Δ in equation (1) is an appropriate value corresponding to the intake performance of the engine 1. A value can be set, for example, 32, 64, etc. can be set as Δ.

In step 140, the reference intake air amount e
The difference tdlkltn is calculated by subtracting the actual intake air amount eklsm from klcrt. In step 150,
The difference tdlkltn obtained in the previous step 140 is -α
% Is determined. α is a positive number, and in this case, α = 4 is set. The difference tdlkltn is-
If it is determined that it is less than α%, the process proceeds to step 160,
If it is determined that the difference tdlkltn is equal to or more than -α%, the process proceeds to step 180.

In step 160, it is determined based on the engine speed ne, the throttle opening ta, and the valve timing vt obtained in step 110 whether or not the engine is in a backflow generating operation state. If it is determined in step 160 that the state is the backflow generating operation state, the actual intake air amount eklsm limited to the upper limit guard value becomes larger than the reference intake air amount eklcrt, and erroneous learning can be performed in a direction to increase the atmospheric pressure correction value. There is. Therefore, the present process ends without performing the atmospheric pressure learning. If it is determined in step 160 that the operation state is not reverse, the process proceeds to step 170.

At step 170, the atmospheric pressure correction value ekpa is updated by adding a predetermined value (in this case, 0.001) to the current atmospheric pressure correction value, and this processing ends.

In step 180, it is determined whether or not the difference tdlkltn obtained in step 140 is larger than α%. When it is determined that the difference tdlkltn is equal to or less than α%, the atmospheric pressure learning is not performed, and the process ends. When it is determined that the difference tdlkltn is larger than α%, the process proceeds to step 190.

At step 190, the atmospheric pressure correction value ekpa is updated by subtracting a predetermined value (in this case, 0.001) from the current atmospheric pressure correction value, and this processing ends. The atmospheric pressure correction value ekpa calculated in step 170 or the atmospheric pressure correction value ekpa calculated in step 190 is stored in the backup RAM and used as a numerical value for correcting the fuel injection control amount and the like. Become.

According to the atmospheric pressure learning device of this embodiment described in detail above, the following effects can be obtained.・
When performing the atmospheric pressure learning, the basic intake air amount eklta at the reference atmospheric pressure is calculated with reference to the intake air amount map based on the engine operating state. This basic intake air amount ekl
Since the reference intake air amount eklcrt considering the change in the engine operating state is calculated based on ta, the reference intake air amount eklcrt takes into account the influence of the delay of the intake air. Accordingly, both the reference intake air amount eklcrt and the actual intake air amount eklsm include the influence of the delay of the intake air, and the difference between the reference intake air amount eklcrtt and the actual intake air amount eklsm is substantially due to the atmospheric pressure difference. Become. Therefore, by comparing the reference intake air amount eklcrt with the actual intake air amount eklsm, it is possible to calculate an accurate atmospheric pressure correction value not only in a stable state of the engine operating state but also in a change of the engine operating state. become able to.

At the time of learning the atmospheric pressure, when it is determined that the operation is the reverse flow generating operation state, and when the actual intake air amount eklsm is larger than the reference intake air amount eklcrt, the increase and update of the atmospheric pressure correction value are prohibited. It is possible to preferably prevent erroneous learning of the atmospheric pressure learning.

When the difference tdlkltn between the reference intake air amount eklcrt and the actual intake air amount eklsm calculated based on the engine operating state is less than -α% or greater than α%, I try to learn. Therefore, the chance of the atmospheric pressure learning does not become excessive, and an appropriate atmospheric pressure correction value can be obtained while appropriately securing the opportunity of the atmospheric pressure learning.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. In the first embodiment, when the actual intake air amount eklsm is larger than the reference intake air amount eklcrt when the internal combustion engine is in the backflow generating operation state, the update of the atmospheric pressure correction value is prohibited from being updated and erroneous learning is prevented. I did it. By prohibiting the increase and updating of the atmospheric pressure correction value in this way, erroneous learning of atmospheric pressure learning can be prevented, but opportunities for atmospheric pressure learning are reduced.

Therefore, in the present embodiment, the actual intake air amount and the reference intake air amount are allowed to include the reverse flow of the intake air, and the atmospheric pressure learning is executed even in the reverse flow generating operation state, and the atmospheric pressure correction value is obtained. Can be updated to the increase side.

In this embodiment, the configuration of the engine system is the same as that of the first embodiment. The atmospheric pressure learning process executed by the electronic control unit 40 in the present embodiment will be described with reference to the flowchart shown in FIG. This process is a process that is periodically and repeatedly executed every preset short time.

When the process proceeds to the routine, the electronic control unit 40 first reads the measurement signal output from the air flow meter 21 in step 200, and based on the measurement signal, the actual intake air passing through the intake passage 6. Quantity ek
lsma is detected. The actual intake air amount eklsma is a value that does not remove the backflow in the backflow generating operation state. The actual intake air amount eklsma is equal to the cylinder 2
Is calculated by the load ratio (percentage) with respect to the stroke volume.

In the following step 210, the first
In the same manner as in the embodiment, the engine speed ne and the throttle opening ta are detected, and the valve timing vt is read.

In the following step 220, the previous step 2
Engine speed ne and throttle opening t obtained in Step 10
Based on a and the valve timing vt, a basic intake air amount ekltaa is calculated with reference to an intake air amount map stored in the ROM. This intake air amount map is
It is set based on the actual intake air amount eklsma measured by the air flow meter 21 at the reference atmospheric pressure in a stable state of the engine operation state such as the engine rotation speed ne, the throttle opening ta, and the valve timing vt. In this intake air amount map, the actual intake air amount e is defined as the basic intake air amount ekltaa in the engine operating state where backflow occurs.
klsma is set. The basic intake air amount ekltaa of this intake air amount map is also set as a load ratio (percentage) to the stroke volume of the cylinder 2.

In the next step 230, the previous step 22
The reference intake air amount eklcr considering the change in the engine operating state based on the basic intake air amount ekltaa calculated at 0
ta is calculated. This is because, as shown in FIG. 3, when the engine operating state changes, the intake air in the intake passage 6 changes with a delay with respect to the change, and the actual intake air amount eklsma
Includes the effects of delay. Basic intake air volume ekl
The reference intake air amount eklcrta calculated on the basis of the taa in consideration of the change in the engine operation state takes into account the influence of the delay of the intake air. Therefore, the reference intake air amount ek
Both lcrta and the actual intake air amount eklsma include the influence of the delay of the intake air, and the difference between the reference intake air amount eklcrta and the actual intake air amount eklsma is substantially due to the atmospheric pressure difference. Incidentally, in the present embodiment, the reference intake air amount eklcrta is calculated by the following equation (2).

[0066]

Eklcrta (i) = eklcrta (i−1) + {ekltaa + eklcrta (i−1)} / Δ (2) where Δ in equation (2) is an appropriate value corresponding to the intake performance of the engine 1. A value can be set, for example, 32, 64, etc. can be set as Δ.

In step 240, the reference intake air amount e
A difference tdlkltn is calculated by subtracting the actual intake air amount eklsma from klcrta. In step 250, it is determined whether or not the difference tdlkltn obtained in step 240 is less than -α%. α is a positive number, and in this case, α = 4 is set. Difference tdlkltn
Is determined to be less than -α%, the routine proceeds to step 260, and if it is determined that the difference tdlkltn is equal to or greater than -α%, the routine proceeds to step 270.

At step 260, the atmospheric pressure correction value ekpa is updated by adding a predetermined value (in this case, 0.001) to the current atmospheric pressure correction value, and this processing ends.

In step 270, it is determined whether or not the difference tdlkltn obtained in step 240 is larger than α%. When it is determined that the difference tdlkltn is equal to or less than α%, the atmospheric pressure learning is not performed, and the process ends. If it is determined that the difference tdlkltn is larger than α%, the process proceeds to step 280.

In step 280, the atmospheric pressure correction value ekpa is updated by subtracting a predetermined value (in this case, 0.001) from the current atmospheric pressure correction value, and this processing ends. Then, the atmospheric pressure correction value ekpa calculated in step 260 or the atmospheric pressure correction value ekpa calculated in step 280 is stored in the backup RAM and used as a numerical value for correcting the fuel injection control amount and the like. Become.

Therefore, according to the present embodiment, the following effects can be obtained in addition to the effects of the first embodiment. When the atmospheric pressure learning is performed, the actual intake air amount eklsma of the air flow meter 21 is set so as to include the backflow. Further, the basic intake air amount ekltaa at the reference atmospheric pressure calculated with reference to the intake air amount map based on the engine operating state is also calculated while allowing the backflow component to be included. Therefore, the reference intake air amount eklc
Both rta and the actual intake air amount eklsma include a backflow, and the difference between the reference intake air amount eklcrta and the actual intake air amount eklsma is substantially due to the atmospheric pressure difference. Therefore, by comparing the reference intake air amount eklcrta with the actual intake air amount eklsma, an accurate atmospheric pressure correction value can be calculated even in the backflow generating operation state, and the atmospheric pressure correction value increases and decreases. Updates to the side can be made.

The actual intake air amount eklsma and the reference intake air amount eklcrta (basic intake air amount ekl
taa) is set to allow backflow components. Therefore, it is not necessary to determine whether the current state is the backflow generating operation state as in step 160 of the first embodiment,
The atmospheric pressure learning process can be simplified.

The embodiment is not limited to the above, but may be modified as follows. In the above embodiments, the difference tdlkl for executing the atmospheric pressure learning is described.
Although the predetermined value α for determining tn is set to 4, the value of α may be appropriately changed according to the intake performance based on the model of the engine 1. Also in this case, the same operation and effect as the above embodiments can be obtained.

In the first embodiment, step 130 is omitted with the basic intake air amount eklta as the reference intake air amount. Then, in the following step 140, the difference tdlkltn may be obtained by subtracting the actual intake air amount eklsm from the basic intake air amount eklta. In this case, erroneous learning toward the increasing side of the atmospheric pressure correction value in the backflow generating operation state can be suitably prevented.

In the second embodiment, the basic intake air amount ekltaa is set as the reference intake air amount in step 230.
Is omitted. Then, in the subsequent step 240, the difference tdlkltn may be obtained by subtracting the actual intake air amount eklsma from the basic intake air amount ekltaa. In this case, erroneous learning toward the increasing side of the atmospheric pressure correction value in the backflow generating operation state can be suitably prevented.

The embodiments described above are applied to an engine using gasoline as a fuel, but may be applied to an engine using LPG as a fuel. Next, other technical ideas that can be grasped from the above embodiments will be described below.

The atmospheric pressure learning device for an internal combustion engine according to any one of claims 1 to 5, wherein the air flow meter determines the amount of heat that the intake air passing through the intake passage takes away from the detection element by the flow rate of the intake air. An atmospheric pressure learning device for an internal combustion engine, which is a thermal air flow meter that outputs a measurement signal related to the atmospheric pressure.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view and a block diagram showing an engine of a first embodiment.

FIG. 2 is a flowchart illustrating an atmospheric pressure learning process according to the first embodiment.

FIG. 3 is a characteristic diagram showing a relationship between a reference intake air amount and an actual intake air amount according to a change with time.

FIG. 4 is a flowchart illustrating an atmospheric pressure learning process according to a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 6 ... Intake path, 8 ... Intake valve, 9 ... Exhaust valve, 17 ... Throttle valve, 20 ... Throttle sensor, 21 ... Air flow meter, 40 ... Electronic control device.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hisao Iyoda 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G084 BA04 BA23 DA04 EB17 EB20 FA01 FA07 FA08 FA10 FA20 FA28 FA33 FA35 3G301 HA01 HA19 JA20 LA01 MA12 NA08 NB02 NB20 NC01 NC02 ND01 ND21 ND22 ND24 ND25 ND28 ND30 ND35 NE01 PA01Z PA04Z PA09Z PA11Z PD01Z PE01Z PE08Z PE10Z PF03Z

Claims (5)

[Claims] An air flow meter for measuring an actual intake air amount passing through an intake passage of an internal combustion engine, and a reference large value based on an engine operating state including an opening degree of a throttle valve provided in the intake passage and an engine rotation speed. Calculating means for calculating a basic intake air amount at atmospheric pressure and calculating a reference intake air amount in consideration of a change in the engine operating state based on the basic intake air amount; and the reference intake air amount and the actual intake air. A learning means for performing atmospheric pressure learning by comparing the amount with an atmospheric pressure learning device. 2. An air flow meter for measuring an actual intake air amount passing through an intake passage of an internal combustion engine, and the air flow meter is calculated according to an engine operating state including an opening degree of a throttle valve provided in the intake passage and an engine rotation speed. Calculating means for calculating a reference intake air amount based on a basic intake air amount at a reference atmospheric pressure; determining means for determining whether the engine operation state is a backflow generation operation state in which a backflow of intake air occurs; Learning means for performing atmospheric pressure learning by comparing a reference intake air amount with the actual intake air amount; and when the engine operation state is determined to be a backflow generation operation state, the actual intake air amount An atmospheric pressure learning device for an internal combustion engine, comprising: a prohibition unit that prohibits the learning unit from increasing and updating the atmospheric pressure correction value when the amount is larger than the intake air amount. 3. An air flow meter for measuring an actual intake air amount passing through an intake passage of the internal combustion engine, and an air flow meter is calculated according to an engine operating state including an opening degree of a throttle valve provided in the intake passage and an engine rotation speed. Calculating means for calculating a reference intake air amount based on a basic intake air amount at a reference atmospheric pressure, learning means for performing atmospheric pressure learning by comparing the reference intake air amount and the actual intake air amount, In the internal-combustion-engine atmospheric pressure learning device comprising: the calculation means stores air amount data set by an actual intake air amount measured by the air flow meter in an arbitrary engine operating state at the reference atmospheric pressure. An atmospheric pressure of the internal combustion engine, wherein the calculating means calculates the basic intake air amount by referring to the air amount data based on the engine operating state at that time. Learning device. 4. An atmospheric pressure learning device for an internal combustion engine according to claim 2, wherein said calculating means is configured to consider a change in the engine operating state based on said basic intake air amount. An atmospheric pressure learning device for an internal combustion engine, which calculates an intake air amount. 5. The atmospheric pressure learning device for an internal combustion engine according to claim 1, wherein said learning means is configured to determine whether a difference between the reference intake air amount and the actual intake air amount is equal to or greater than a predetermined value. An atmospheric pressure learning device for an internal combustion engine, which performs atmospheric pressure learning.