JP4415506B2 - Atmospheric pressure learning device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an atmospheric pressure learning device for an internal combustion engine that learns atmospheric pressure based on an intake air amount ratio of the internal combustion engine without using an atmospheric pressure sensor.
[0002]
[Prior art]
In recent years, for example, Japanese Patent Publication No. 6-81914 discloses an atmospheric pressure learning correction amount used for engine fuel injection control (air-fuel ratio control) with an inexpensive configuration without using an atmospheric pressure sensor. Has been. This uses the intake air amount map at the reference atmospheric pressure set according to the engine operating state including the engine speed and the throttle opening, and the intake air at the reference atmospheric pressure according to the engine operating state at that time. Find the amount. Then, the 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.
[0003]
By the way, the flow of the intake air in the intake passage is affected by the intake pulsation of the engine, and when the throttle opening increases, the intake pulsation increases in the low engine speed region, and the intake air in the intake passage is affected by the influence. Backflow occurs. When such a backflow occurs, the air flow meter, in principle, measures the amount of air that has flowed back, and thus the air amount is excessively measured with respect to the actually sucked air amount. For this reason, in the engine operation state where the backflow occurs, the intake air amount measured by the air flow meter includes an error due to the backflow, and an accurate atmospheric pressure correction value cannot be calculated. In order to eliminate such error due to backflow, when calculating the atmospheric pressure correction value, the maximum intake air amount at the reference atmospheric pressure is calculated, and the actual intake air flow meter measured with an air flow meter with this maximum intake air amount as the upper limit guard value. The intake air amount is limited to the upper limit guard value or less.
[0004]
The intake air amount map is basically set based on the actual intake air amount measured by the air flow meter in a stable state of the throttle opening and the engine speed at the reference atmospheric pressure. Note that, in an engine operating state in which backflow occurs, a value that takes into account the correction value in the air-fuel ratio control is set with respect to the upper limit guard value.
[0005]
[Problems to be solved by the invention]
Therefore, in the technique described in the above publication, the reference intake air amount and the actual intake air amount are not affected by the delay of the intake air when the engine operating state is stable when measuring the actual intake air amount. The difference is due to the atmospheric pressure difference. Therefore, in the stable state of the engine operation state, the atmospheric pressure learning can be performed with high accuracy by comparing the reference intake air amount and the actual intake air amount.
[0006]
However, when the engine operating state changes, such as when the throttle opening changes or the engine speed changes, the intake air changes with a delay relative to the change in the engine operating state. The effects of are included. For this reason, the difference between the reference intake air amount and the actual intake air amount based on the engine operating condition at that time includes the effect of the intake air delay in addition to the atmospheric pressure difference, and calculates an accurate atmospheric pressure correction value. There is a problem that it is impossible to learn and mislearns.
[0007]
Further, when the actual intake air amount measured by the air flow meter becomes a large value in the engine operation state where the reverse flow occurs, the actual intake air amount is limited to the upper guard value. However, in the engine operating state where the reverse flow occurs, the reference intake air amount referring to the intake air amount map is set with a value that takes into account the correction value of the air-fuel ratio control. It may be larger than the intake air volume. In this case, there is a problem of erroneous learning in the direction of increasing the atmospheric pressure correction value.
[0008]
The present invention has been made in view of such circumstances, and an object thereof is 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 there.
[0009]
Another object of the present invention is to provide an atmospheric pressure learning device for an internal combustion engine that can prevent erroneous learning of atmospheric pressure learning in a backflow generation operation state in which a backflow of intake air is generated.
[0010]
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 a backflow of intake air is generated.
[0013]
[Means for Solving the Problems]
  Claim 1The air flow meter for measuring the actual intake air amount passing through the intake passage of the internal combustion engine, and the calculation according to the engine operating state including the opening degree of the throttle valve provided in the intake passage and the engine speed Calculating means for calculating a reference intake air amount based on a basic intake air amount at a reference atmospheric pressure, a determination means for determining whether the engine operation state is a reverse flow generation operation state in which a reverse flow of intake air is generated, Learning means for performing atmospheric pressure learning by comparing the reference intake air amount and 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 is And a prohibiting unit that prohibits the updating of the atmospheric pressure correction value by the learning unit when the amount is larger than a reference intake air amount.
[0014]
  the aboveAccording to the configuration, when the determination unit determines that the operation state is the backflow generation operation state, the prohibition unit prohibits the increase update of the atmospheric pressure correction value, thereby preventing erroneous learning of the atmospheric pressure learning.
[0015]
  Claim 2The air flow meter for measuring the actual intake air amount passing through the intake passage of the internal combustion engine, and the calculation according to the engine operating state including the opening degree of the throttle valve provided in the intake passage and the engine speed Calculating means for calculating a reference intake air amount based on a basic intake air amount at a reference atmospheric pressure, and learning means for performing atmospheric pressure learning by comparing the reference intake air amount with the actual intake air amount; In the apparatus for learning atmospheric pressure of an internal combustion engine, 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. Storing means for calculating the basic intake air amount with reference to the air amount data based on the engine operating state at that time.
[0016]
  the aboveAccording to the configuration, the backflow component is included in the actual intake air amount measured by the air flow meter in the backflow generation operation state. The air amount data for calculating the reference intake air amount is set at the actual intake air amount measured at the reference atmospheric pressure in an arbitrary engine operation state, and therefore includes the back flow component in the reverse flow generation operation state. . Therefore, even if the engine operation state is the backflow 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, atmospheric pressure learning can be performed with high accuracy.
[0017]
  Claim 3The invention described in claim1 or claim 2In the atmospheric pressure learning apparatus for an internal combustion engine according to claim 1, the calculation means calculates a reference intake air amount that takes into account changes in the engine operating state based on the basic intake air amount.
[0018]
  the aboveAccording to the configuration, 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 based on the basic intake air amount. Therefore, the reference intake air amount takes into account the delay of intake air. Therefore, both the reference intake air amount and the actual intake air amount include an effect due to the delay of the intake air, and the difference between the reference intake air amount and the actual intake air amount is due to the atmospheric pressure difference. Therefore, by comparing the reference intake air amount and the actual intake air amount, atmospheric pressure learning can be accurately performed even when the engine operating state changes.
[0019]
  Claim 4The invention described in claim 1Any one of 3In the atmospheric pressure learning device for an internal combustion engine according to claim 1, the learning means performs atmospheric pressure learning when a difference between the reference intake air amount and the actual intake air amount is a predetermined value or more.
[0020]
  the aboveAccording to the configuration, when the difference between the calculated reference intake air amount and the actual intake air amount is equal to or greater than a predetermined value, the atmospheric pressure learning is performed based on the reference intake air amount and the actual intake air amount. The learning opportunity does not become excessive, and an appropriate atmospheric pressure correction value can be obtained while securing the atmospheric pressure learning opportunity.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
A first embodiment of the present invention will be described below with reference to FIGS.
[0022]
FIG. 1 shows a schematic configuration of an engine system in the present embodiment. The engine 1 includes a plurality of cylinders 2, and pistons 3 provided in the respective cylinders 2 are connected to a crankshaft 1 a serving as an output shaft, and can be moved up and down in each cylinder 2. Yes. In each cylinder 2, the upper side of the piston 3 constitutes a combustion chamber 4.
[0023]
A spark plug 5 provided corresponding to each combustion chamber 4 ignites the air-fuel mixture introduced into the combustion chamber 4. Each of the intake port 6 a and the exhaust port 7 a provided corresponding to each combustion chamber 4 constitutes a part of the intake passage 6 and the exhaust passage 7.
[0024]
Each of the intake valve 8 and the exhaust valve 9 provided corresponding to each combustion chamber 4 opens each port 6a, 7a. Each of these valves 8 and 9 operates based on the rotation of different camshafts 10 and 11. Timing pulleys 12 and 13 provided at the tips of the camshafts 10 and 11 are connected to the crankshaft 1a via a timing belt 14, respectively.
[0025]
During operation of the engine 1, the rotational force of the crankshaft 1 a is transmitted to the camshafts 10 and 11 via the timing belt 14 and the timing pulleys 12 and 13. As the camshafts 10 and 11 rotate, the valves 8 and 9 operate. The valves 8 and 9 can be operated 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. It has become.
[0026]
An air cleaner 15 provided at the inlet of the intake passage 6 cleans the outside air taken into the passage 6. Injectors 16 provided in the vicinity of each intake port 6a inject fuel toward the intake port 6a.
[0027]
During operation of the engine 1, outside air is taken into the intake passage 6 via the air cleaner 15. 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 the 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 spark plug 5 to explode and burn. As a result, the piston 3 is actuated to rotate the crankshaft 1a, and an output is obtained to the engine 1. The exhaust gas after combustion is led out from the combustion chamber 4 in the exhaust stroke in which the exhaust valve 9 opens the exhaust port 7a, and is discharged to the outside through the exhaust passage 7.
[0028]
The throttle valve 17 provided in the intake passage 6 is opened and closed in response to an operation of an accelerator pedal (not shown). By adjusting the opening degree 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 on the downstream side of the throttle valve 17 smoothes the pulsation of the intake air.
[0029]
An intake air temperature sensor 19 provided in the vicinity of the air cleaner 15 measures the intake air temperature tha and outputs a measurement signal corresponding to the measured value. The throttle sensor 20 provided in the vicinity of the throttle valve 17 measures the opening (throttle opening) ta of the throttle valve 17 and outputs a measurement signal corresponding to the measured value.
[0030]
The hot-wire air flow meter 21 provided upstream of the throttle valve 17 includes a metal wire (heat wire) that generates heat when energized as a detection element. The air flow meter 21 outputs a voltage having a magnitude corresponding to the amount of heat taken by the intake air passing through the air flow meter 21 from the detection element as a measurement signal corresponding to the actual intake air amount eklsm passing through the intake passage 6. .
[0031]
On the other hand, the catalytic converter 22 provided in the middle of the exhaust passage 7 purifies the exhaust gas by the built-in three-way catalyst 23. The oxygen sensor 24 provided in the exhaust passage 7 measures the oxygen concentration Ox in the exhaust gas and outputs a measurement signal corresponding to the measured value. The water temperature sensor 25 provided in the engine 1 measures the temperature (cooling water temperature) thw of cooling water for cooling the engine 1 and outputs a measurement signal corresponding to the measured value.
[0032]
The distributor 26 distributes the high voltage output from the igniter 27 to each spark plug 5 as an ignition signal for igniting each spark plug 5. The operation timing of each spark plug 5 is determined by the timing at which the igniter 27 outputs a high voltage.
[0033]
A rotor (not shown) built in the distributor 26 is rotated by a camshaft 11 that rotates in synchronization with the crankshaft 1a. The rotational speed sensor 28 provided in the distributor 26 measures the rotational speed (engine rotational speed) ne of the engine 1 based on the rotation of the rotor, and outputs the measured value as a pulse signal. The cylinder discrimination sensor 29 provided in the distributor 26 measures the 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 1 a rotates twice for a series of four strokes of the engine 1. While the crankshaft 1a rotates twice, the rotational speed sensor 28 outputs a signal of one pulse every 30 ° CA. The cylinder discrimination sensor 29 outputs a signal of one pulse every 360 ° CA.
[0034]
In the apparatus of this embodiment, a known valve timing control mechanism 30 is provided at the tip of the camshaft 10 integrally with the timing pulley 12. In the operation of the valve timing control mechanism 30, 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 adjusted by the oil control valve 33. The oil control valve 33 is controlled to open and close based on a command signal from the electronic control device 40.
[0035]
The valve timing control mechanism 30 is formed integrally with the timing pulley 12 and has an internal rotating body (not shown) formed integrally with the camshaft 10 therein. The valve timing control mechanism 30 is actuated by the hydraulic pressure supplied into the mechanism 30, and the camshaft 10 and the timing pulley 12 rotate relative to each other as the outer rotating body and the inner rotating body rotate relative to each other. Is configured to do. As a result of the relative rotation between the camshaft 10 and the timing pulley 12, the valve timing (control advance value) vt of the intake valve 8 is changed.
[0036]
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.
[0037]
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 24, the water temperature sensor 25, the rotation speed sensor 28, and the cylinder discrimination sensor 29. The output is input to the electronic control unit 40.
[0038]
The electronic control unit 40 is a microcomputer system, and recognizes (detects) various engine operating states such as the amount of intake air taken into the engine 1, the engine speed, and the throttle opening based on the outputs of these sensors. Then, the electronic control unit 40 executes atmospheric pressure (altitude) learning according to the present invention in addition to fuel injection control, ignition timing control, 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), a backup RAM, and the like. The ROM stores various control programs and various maps. The various maps include an intake air amount map at the reference atmospheric pressure used for atmospheric pressure learning. The CPU executes arithmetic processing based on the input signal. The RAM stores data in the calculation / control process of the CPU. The backup RAM is supplied with power by being directly connected to a battery (not shown), and is used to store data (for example, various learning values) that should be retained even when the ignition switch is off. Is done.
[0039]
The engine control process of the electronic control unit 40 executed in the internal combustion engine (engine) having the above hardware configuration will be described below.
The fuel injection control basically calculates the fuel injection amount that achieves a predetermined target air-fuel ratio, that is, the injection time by the injector 16 based on the intake air amount (mass) per one rotation of the engine. The injector 16 is controlled to inject fuel when a predetermined crank angle is reached. The intake air amount (mass) per rotation 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. When 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 signals from the oxygen sensor 24, air-fuel ratio learning. Corrections etc. are added. Note that the air-fuel ratio learning correction is such that the median value of correction values in the air-fuel ratio feedback correction becomes the stoichiometric air-fuel ratio.
[0040]
Further, in the ignition timing control, the state of the engine 1 is comprehensively determined based on the engine rotational speed obtained from the rotational speed sensor 28 and signals from other sensors, the optimum ignition timing is determined, and an ignition signal is sent to the igniter 27. Is to send.
[0041]
In the various controls described above, correction based on altitude, that is, atmospheric pressure is required, and atmospheric pressure learning for obtaining the atmospheric pressure correction value is executed. Also in the atmospheric pressure learning of the present embodiment, the reference intake air amount at the reference atmospheric pressure according to the engine operating state at that time is determined using the intake air amount map at the reference atmospheric pressure set according to the engine operating state. Ask. Then, the 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.
[0042]
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 periodically executed every predetermined time.
[0043]
When the process proceeds to this routine, the electronic control unit 40 first reads the measurement signal output from the air flow meter 21 in step 100, and based on this measurement signal, calculates the actual intake air amount eklsm passing through the intake passage 6. To detect. This 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 operation state where the intake air backflow occurs. The actual intake air amount eklsm is calculated as a load factor (percentage) with respect to the stroke volume of the cylinder 2.
[0044]
In the following step 110, the engine speed ne and the throttle opening degree ta are detected, and the valve timing vt is read.
The engine rotation speed ne and the throttle opening degree ta are obtained based on measurement signals output from the rotation speed sensor 28 and the throttle sensor 20, respectively, as described above.
[0045]
On the other hand, the valve timing vt is obtained as follows through a separate routine (not shown) based on measurement signals output from the rotational speed sensor 28 and the cam sensor 34.
[0046]
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 deviation between the two output timings.
[0047]
Incidentally, the electronic control unit 40 appropriately determines a target valve timing in accordance with each operation state of the engine 1, and always executes feedback control so that the actual valve timing vt matches the target valve timing. ing. For this reason, the valve timing control mechanism 30 is driven based on the control command of the electronic control unit 40, and the valve timing vt is constantly changed.
[0048]
In the following step 120, the basic intake air amount eklta is calculated with reference to the intake air amount map stored in the ROM, based on the engine speed ne, the throttle opening degree ta, and the valve timing vt obtained in the previous step 110. To do. This intake air amount map is based on the actual intake air amount eklsm measured by the air flow meter 21 at a reference atmospheric pressure in a stable state of the engine operating state such as the engine rotational speed ne, the throttle opening degree 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 backflow occurs is set to a value that considers the correction value in the air-fuel ratio control with respect to the upper limit guard value of the actual intake air amount eklsm. The basic intake air amount eklta of this intake air amount map is also set as a load factor (percentage) with respect to the stroke volume of the cylinder 2.
[0049]
In the next step 130, a reference intake air amount eklcrt that takes into account changes in the engine operating state is calculated based on the basic intake air amount eklta calculated in the previous step 120. 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 an influence due to the delay. The basic intake air amount eklta is an air amount in a stable state of the engine operation state. Therefore, 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 effect of the intake air delay in addition to the atmospheric pressure difference. On the other hand, the reference intake air amount eklcrt calculated in consideration of changes in the engine operating state based on the basic intake air amount eklta takes into consideration the influence of the intake air delay. 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 difference between the reference intake air amount eklcrt and the actual intake air amount eklsm is substantially due to the difference in atmospheric pressure. Become. Incidentally, in the present embodiment, the reference intake air amount eklcrt is calculated by the following equation (1).
[0050]
[Expression 1]
eklcrt (i) = eklcrt (i-1)
+ {Eklta + eklcrt (i-1)} / Δ (1)
It should be noted that an appropriate value corresponding to the intake performance of the engine 1 can be set as Δ in the expression (1), and for example, 32, 64, etc. can be set as Δ.
[0051]
In step 140, the difference tdlkltn is calculated by subtracting the actual intake air amount eklsm from the reference intake air amount eklcrt.
In step 150, it is determined whether or not the difference tdlkltn obtained in the previous step 140 is less than -α%. α is a positive number. In this case, α = 4 is set. If it is determined that the difference tdlkltn is less than -α%, the process proceeds to step 160, and if it is determined that the difference tdlkltn is greater than or equal to -α%, the process proceeds to step 180.
[0052]
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 the reverse flow generation operation state. If it is determined in step 160 that the engine is in the reverse flow generation operation state, the actual intake air amount eklsm limited to the upper guard value becomes larger than the reference intake air amount eklcrt, and erroneously learned in the direction of increasing the atmospheric pressure correction value. There is sex. For this reason, the atmospheric pressure learning is not performed and the present process is terminated. If it is determined in step 160 that the reverse flow generation operation state is not reversed, the process proceeds to step 170.
[0053]
In step 170, the atmospheric pressure correction value ekpa is updated by adding a predetermined value (0.001 in this case) to the current atmospheric pressure correction value, and this process is terminated.
[0054]
In step 180, it is determined whether or not the difference tdlkltn obtained in the previous step 140 is larger than α%. If it is determined that the difference tdlkltn is equal to or less than α%, the atmospheric pressure learning is not performed and the present process is terminated. If it is determined that the difference tdlkltn is greater than α%, the process proceeds to step 190.
[0055]
In step 190, the atmospheric pressure correction value ekpa is updated by subtracting a predetermined value (0.001 in this case) from the current atmospheric pressure correction value, and this process is terminated. 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.
[0056]
According to the atmospheric pressure learning device of the present 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. Since the reference intake air amount eklcrt is calculated based on the basic intake air amount eklta in consideration of changes in the engine operating state, the reference intake air amount eklcrt takes into account the influence of the intake air delay. 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 difference between the reference intake air amount eklcrt and the actual intake air amount eklsm is substantially due to the difference in atmospheric pressure. Become. Therefore, by comparing the reference intake air amount eklcrt and the actual intake air amount eklsm, an accurate atmospheric pressure correction value can be calculated not only in the stable state of the engine operation state but also in the change of the engine operation state. become able to.
[0057]
-When the atmospheric pressure learning is performed, when it is determined that the reverse flow generation operation state is present, when the actual intake air amount eklsm is larger than the reference intake air amount eklcrt, the update update of the atmospheric pressure correction value is prohibited. Mislearning can be suitably prevented.
[0058]
The electronic control unit 40 performs atmospheric pressure learning when the difference tdlkltn between the reference intake air amount eklcrt calculated based on the engine operation state and the actual intake air amount eklsm is less than −α% or greater than α%. I am doing so. Therefore, there are no excessive atmospheric pressure learning opportunities, and an appropriate atmospheric pressure correction value can be obtained while suitably securing the atmospheric pressure learning opportunity.
[0059]
(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG.
In the first embodiment, when the internal combustion engine is in the backflow generating operation state, if the actual intake air amount eklsm is larger than the reference intake air amount eklcrt, the atmospheric pressure correction value is inhibited from being updated to prevent erroneous learning. I did it. In this way, if the incremental update of the atmospheric pressure correction value is prohibited, erroneous learning of atmospheric pressure learning can be prevented, but the opportunity for atmospheric pressure learning is reduced.
[0060]
Therefore, in the present embodiment, the actual intake air amount and the reference intake air amount are allowed to include the backflow portion of the intake air, the atmospheric pressure learning is executed even in the backflow generation operation state, and the atmospheric pressure correction value is increased. You can update to.
[0061]
In the present 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 repeatedly executed periodically every preset short time.
[0062]
When the process shifts to the routine, first, in step 200, the electronic control unit 40 reads the measurement signal output from the air flow meter 21, and based on this measurement signal, calculates the actual intake air amount eklsma passing through the intake passage 6. To detect. This actual intake air amount eklsma is a value that does not remove the backflow component in the backflow generation operation state. The actual intake air amount eklsma is calculated as a load factor (percentage) with respect to the stroke volume of the cylinder 2.
[0063]
In the subsequent step 210, the engine speed ne and the throttle opening ta are detected and the valve timing vt is read in the same manner as in the first embodiment.
[0064]
In the following step 220, the basic intake air amount ekltaa is calculated with reference to the intake air amount map stored in the ROM based on the engine speed ne, the throttle opening ta, and the valve timing vt obtained in the previous step 210. To do. This intake air amount map is set based on the actual intake air amount eklsma measured by the air flow meter 21 at a reference atmospheric pressure in a stable state of the engine operating state such as the engine rotational speed ne, the throttle opening degree ta, and the valve timing vt. Has been. In this intake air amount map, the actual intake air amount eklsma is set as the basic intake air amount ekltaa in the engine operating state in which the backflow occurs. The basic intake air amount ekltaa in the intake air amount map is also set as a load factor (percentage) with respect to the stroke volume of the cylinder 2.
[0065]
In the next step 230, a reference intake air amount eklcrta that takes into account changes in the engine operating state is calculated based on the basic intake air amount ekltaa calculated in the previous step 220. 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 influence of the delay. The reference intake air amount eklcrta calculated in consideration of changes in the engine operating state based on the basic intake air amount ekltaa takes into consideration the influence of the intake air delay. Accordingly, both the reference intake air amount eklcrta and the actual intake air amount eklsma include an effect due to 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 difference in atmospheric pressure. Become. Incidentally, in the present embodiment, the reference intake air amount eklcrta is calculated by the following equation (2).
[0066]
[Expression 2]
eklcrta (i) = eklcrta (i-1)
+ {Ekltaa + eklcrta (i-1)} / Δ (2)
It should be noted that an appropriate value corresponding to the intake performance of the engine 1 can be set as Δ in the expression (2). For example, 32, 64, etc. can be set as Δ.
[0067]
In step 240, the difference tdlkltn is calculated by subtracting the actual intake air amount eklsma from the reference intake air amount eklcrta.
In step 250, it is determined whether or not the difference tdlkltn obtained in the previous step 240 is less than -α%. α is a positive number. In this case, α = 4 is set. If it is determined that the difference tdlkltn is less than -α%, the process proceeds to step 260, and if it is determined that the difference tdlkltn is equal to or greater than -α%, the process proceeds to step 270.
[0068]
In step 260, the atmospheric pressure correction value ekpa is updated by adding a predetermined value (0.001 in this case) to the current atmospheric pressure correction value, and this process is terminated.
[0069]
In Step 270, it is determined whether or not the difference tdlkltn obtained in the previous Step 240 is larger than α%. If it is determined that the difference tdlkltn is equal to or less than α%, the atmospheric pressure learning is not performed and the present process is terminated. If it is determined that the difference tdlkltn is greater than α%, the process proceeds to step 280.
[0070]
In step 280, the atmospheric pressure correction value ekpa is updated by subtracting a predetermined value (0.001 in this case) from the current atmospheric pressure correction value, and this process is terminated. 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.
[0071]
Therefore, according to the present embodiment, the following effects can be obtained in addition to the effects of the first embodiment.
When performing the atmospheric pressure learning, the actual intake air amount eklsma of the air flow meter 21 is set to allow back flow. 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, both the reference intake air amount eklcrta and the actual intake air amount eklsma include a backflow component, and the difference between the reference intake air amount eklcrta and the actual intake air amount eklsma is almost 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 generation operation state. Update to the side.
[0072]
Further, the actual intake air amount eklsma and the reference intake air amount eklcrta (basic intake air amount ekltaa) are set so as to allow a backflow component to be included. Therefore, it is not necessary to determine whether or not it is in the backflow generation operation state as in step 160 of the first embodiment, and the atmospheric pressure learning process can be simplified.
[0073]
In addition, embodiment is not limited above, You may change as follows.
In each of the above embodiments, the predetermined value α for determining the difference tdlkltn for executing the atmospheric pressure learning is set to 4, but the value of α is appropriately changed according to the intake performance based on the model of the engine 1. It may be. Even in this case, the same operations and effects as those of the above embodiments can be obtained.
[0074]
In the first embodiment, the basic intake air amount eklta is set as the reference intake air amount, and step 130 is omitted. In the subsequent 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 of the atmospheric pressure correction value to the increasing side in the backflow generation operation state can be suitably prevented.
[0075]
In the second embodiment, the basic intake air amount ekltaa is set as the reference intake air amount, and step 230 is omitted. In the following 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 of the atmospheric pressure correction value to the increasing side in the backflow generation operation state can be suitably prevented.
[0076]
  -Although each said embodiment was implemented to the engine which uses gasoline as a fuel, you may implement to the engine which uses LPG as a fuel..
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view and a block diagram showing an engine of a first embodiment.
FIG. 2 is a flowchart showing atmospheric pressure learning processing 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 as a function of time.
FIG. 4 is a flowchart showing atmospheric pressure learning processing according to the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine, 6 ... Intake passage, 8 ... Intake valve, 9 ... Exhaust valve, 17 ... Throttle valve, 20 ... Throttle sensor, 21 ... Air flow meter, 40 ... Electronic control apparatus.

Claims (5)

  An air flow meter for measuring the actual intake air amount passing through the intake passage of the internal combustion engine;
  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 engine operating state including an opening degree of a throttle valve provided in the intake passage and an engine rotation speed;
  Determining means for determining whether or not the engine operation state is a reverse flow generation operation state in which a reverse flow of intake air is generated;
  Learning means for performing atmospheric pressure learning by comparing the reference intake air amount and the actual intake air amount;
  When it is determined that the engine operating state is a backflow generation operating state, a prohibiting unit that prohibits an update of the atmospheric pressure correction value by the learning unit when the actual intake air amount is larger than the reference intake air amount;
An atmospheric pressure learning device for an internal combustion engine, comprising:   An air flow meter for measuring the actual intake air amount passing through the intake passage of the internal combustion engine;
  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 engine operating state including an opening degree of a throttle valve provided in the intake passage and an engine rotation speed;
  Learning means for performing atmospheric pressure learning by comparing the reference intake air amount and the actual intake air amount;
In an atmospheric pressure learning device for an internal combustion engine comprising:
  The calculation means includes storage means for storing 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, and the calculation means then An atmospheric pressure learning device for an internal combustion engine, wherein the basic intake air amount is calculated with reference to the air amount data based on the engine operating state of the engine.   The atmospheric pressure learning device for an internal combustion engine according to claim 1 or 2,
  The atmospheric pressure learning device for an internal combustion engine, wherein the calculating means calculates a reference intake air amount in consideration of a change in the engine operating state based on the basic intake air amount.   In the atmospheric pressure learning apparatus for an internal combustion engine according to any one of claims 1 to 3,
  The atmospheric pressure learning device for an internal combustion engine, wherein the learning means performs atmospheric pressure learning when a difference between the reference intake air amount and the actual intake air amount is a predetermined value or more.   In the atmospheric pressure learning device for an internal combustion engine according to any one of claims 1 to 4,
  The atmospheric pressure learning device for an internal combustion engine, wherein the air flow meter is a thermal air flow meter that outputs, as a measurement signal relating to the flow rate of the intake air, the amount of heat taken by the intake air passing through the intake passage from the detection element .

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