JP2789005B2 - Control device for internal combustion engine - Google Patents

Description

The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine that calculates an engine control amount based on a throttle opening and an engine speed. It is.

[Prior Art] Conventionally, as this type of apparatus, for example, Japanese Patent Application Laid-Open No. Sho 62-168949
The technology disclosed in Japanese Patent Laid-Open Publication No. H10-260, is known.

In the technique of this publication, intake flow rate data obtained based on the relationship between the throttle opening and the engine speed is stored in advance. Then, a theoretical intake flow rate is searched from the intake flow rate data based on the detected values of the throttle opening degree and the engine speed detected by the throttle opening degree sensor and the rotation number sensor. Further, a basic injection amount is calculated based on the searched theoretical intake air flow rate and a detected value of the engine speed by a speed sensor, and the injection control from the fuel injection valve is executed in accordance with the calculated value. . By executing the fuel injection control in this manner, especially during the transition of the operation in which the throttle opening changes, the basic injection amount is calculated with high accuracy to realize a good air-fuel ratio control, thereby improving the driving performance. Was being planned.

On the other hand, an independent throttle type internal combustion engine in which a throttle valve is provided for each cylinder downstream of a surge tank provided in the middle of an intake passage is generally known. In this independent throttle type internal combustion engine, the amount of air taken into each cylinder is substantially equal to the flow rate of intake air passing through each throttle valve. For this reason, in this type of internal combustion engine, unlike a normal internal combustion engine in which a throttle valve is provided on the upstream side of the surge tank, there is no first-order delay in the measurement output of the air flow meter that measures the intake air flow.

Therefore, when the technique of the above publication is applied to an independent throttle type internal combustion engine, the measured value of the intake air flow rate by the air flow meter can be used as it is for the calculation of the basic injection amount. Then, only during the transient operation when the throttle opening changes, the basic injection amount may be calculated using the theoretical intake flow rate retrieved from the throttle opening and the engine speed.

[Problems to be Solved by the Invention] However, even when the technology of the above-mentioned publication is applied to an internal combustion engine of an independent throttle type, differences in intake air leakage due to product tolerances of the throttle valve and contamination due to aging of the throttle valve. There is a possibility that the air flow may be affected by differences in the amount of intake air leakage due to deterioration or deterioration, or clogging of the air cleaner. In this case, a difference occurs between the theoretical intake air flow rate determined by the throttle opening and the engine speed and the amount of air actually taken into each cylinder, and a difference occurs in the engine control amount such as the fuel injection amount. This may cause emission and drivability to deteriorate.

The present invention has been made in view of the above-described circumstances, and an object thereof is to constantly control an engine control amount related to the operation of an internal combustion engine in accordance with a product tolerance of a throttle valve and a difference in intake air flow due to a change with time thereof. An object of the present invention is to provide a control device for an internal combustion engine that can be optimized.

[Means for Solving the Problems] In order to achieve the above object, in the present invention,
As shown in FIG. 1, in an independent throttle type internal combustion engine M4 provided with a throttle valve M3 for each cylinder downstream of a surge tank M2 provided in the middle of the intake passage M1, a throttle valve M3 is provided. Throttle opening detection means M5 for detecting the opening degree, engine speed detection means M6 for detecting the rotation speed of the internal combustion engine M4, intake flow rate measurement means M7 for measuring the actual intake flow rate passing through the intake passage M1, Smoothing measurement value calculating means M8 for smoothing the actual intake air flow measurement value to gradually change the actual intake flow measurement value and calculating the smoothing measurement value, and the opening degree of the throttle valve M3 and the rotation speed of the internal combustion engine M4 are calculated. A steady-state intake flow rate calculating means M9 for calculating a theoretical steady-state intake flow rate according to a predetermined relation as a parameter, and a theoretical steady-state intake flow rate equal to a smoothed measured value when a predetermined relation is set. Flow rate gradually Smoothed theoretical value calculation means for calculating an averaged smoothed value by performing smoothing processing so that it changes in various ways
M10, a final intake flow rate calculating means M11 for adding a difference between the theoretical steady intake flow rate and the smoothed theoretical value to the smoothed measurement value to calculate a final intake flow rate, and the final intake rate calculated Engine control amount calculating means M12 for calculating an engine control amount based on the flow rate.

[Operation] According to the above configuration, as shown in FIG. 1, a throttle valve is provided for each cylinder downstream of the surge tank M2.
M3 is provided. Therefore, during operation of the internal combustion engine M4, the amount of air taken into each cylinder is
The intake flow rate passing through M3 is almost equal to the actual intake flow rate measured by the intake flow rate measuring means M7, and there is no first-order lag.

In this state, the throttle opening detecting means M5 detects the opening of the throttle valve M3, that is, the throttle opening. The engine speed detecting means M6 detects the speed of the internal combustion engine M4, that is, the engine speed. The intake flow rate measuring means M7 is the intake passage
Measure the actual inspiratory flow through M1.

Then, in response to the results of the above detection and measurement, the smoothed measurement value calculating means M8 performs a smoothing process so that the actual intake flow rate measured value is gradually changed, and calculates the smoothed measured value. Further, the steady intake air flow rate calculating means M9 calculates a theoretical steady intake air flow rate based on the throttle opening and the engine speed in accordance with a predetermined relationship using these as parameters.

Then, upon receiving the above calculation result, the smoothing theoretical value calculating means M10 gradually sets the theoretical steady intake air flow rate so as to become equal to the calculated smoothing measured value when a predetermined relationship is set. The average value is calculated by performing the averaging process so that the average value changes. Further, the final intake flow rate calculating means M11 adds the difference between the theoretical steady intake flow rate and the calculated averaged theoretical value to the calculated averaged measured value to calculate the final intake flow rate. Then, based on the final intake flow rate thus obtained, the engine control amount calculating means M12 calculates the engine control amount such as the fuel injection amount and the ignition timing.

Therefore, even if the actual intake flow rate measured by the intake flow rate measuring means M7 fluctuates (periodic fluctuation) due to intake air pulsation in the intake passage M1, the measured value is smoothed by the smoothed measured value calculating means M8. It is processed. Therefore, a gradually changing smoothed measurement value from which the influence of the intake pulsation or the like is removed is obtained.

If there is a difference in the amount of intake air leak due to the product tolerance of the throttle valve M3 or its change over time, the smoothed measurement value calculated by the smoothed measurement value calculation means M8 is used as the amount of intake air leakage. And so on. On the other hand, the difference between the theoretical steady-state intake flow rate calculated by the steady-state intake flow rate calculating means M9 and the smoothed theoretical value calculated by the smoothed theoretical value calculating means M10 changes according to a difference in the amount of intake flow leak or the like. Never. For this reason, the final intake flow rate calculated by the final intake flow rate calculation means M11 always has a value that reflects the intake flow leak amount and the like. As a result, the engine control amount such as the fuel injection amount and the ignition timing calculated by the engine control amount calculating means M12 becomes a value in consideration of the intake air leakage amount and the like.

First Embodiment Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS.

FIG. 2 is a schematic configuration diagram showing a gasoline engine system to which the control device for an internal combustion engine according to the present invention is applied. An engine 1 as an internal combustion engine mounted on a vehicle includes an intake passage 2 and an exhaust passage 3. An air cleaner 4 is provided at an inlet of the intake passage 2. A surge tank 5 is provided in the middle of the intake passage 2. Downstream of the surge tank 5, an intake manifold that communicates with each cylinder (in this case, four cylinders) of the engine 1 is provided.
2a, 2b, 2c and 2d are provided. Further, near the intake manifolds 2a to 2d, fuel injectors 6A, 6B,
6C and 6D are provided respectively. On the other hand, on the outlet side of the exhaust passage 3, a catalytic converter 7 having a built-in three-way catalyst is provided.

Then, the engine 1 takes in outside air from the air cleaner 4 through the intake passage 2. At the same time as taking in the outside air, the engine 1 takes in the fuel injected from each of the injectors 6A to 6D. Further, the engine 1 explodes and burns a mixture of the taken fuel and the outside air in each combustion chamber to obtain a driving force, and then discharges the exhaust gas from the exhaust passage 3 to the outside via the catalytic converter 7. I do.

In this embodiment, the engine 1 is of an independent throttle type, and throttle valves 8A, 8B, 8C, 8D are provided in the intake manifolds 2a to 2d on the downstream side of the surge tank 5, respectively. Each of the throttle valves 8A to 8D is opened and closed in conjunction with operation of an accelerator pedal (not shown).
Then, by opening and closing the respective throttle valves 8A to 8D, the intake air flow in each of the intake manifolds 2a to 2d is adjusted.

In the vicinity of the throttle valves 8A to 8D, a throttle opening sensor 21 as throttle opening detecting means for detecting the opening of the throttle valves, that is, the throttle opening TA, is provided. or,
On the upstream side of the surge tank 5, there is provided a well-known air flow meter 22 as an intake flow rate measuring means for measuring an actual intake flow rate (intake rate per second) GA passing through the intake passage 2. In this embodiment, a movable vane type air flow meter 22 is used. Further, an oxygen sensor 23 for detecting the oxygen concentration in the exhaust gas, that is, for detecting the exhaust air-fuel ratio in the exhaust gas passage 3 is provided in the exhaust passage 3. Further, the engine 1 is provided with a water temperature sensor 24 for detecting the temperature of the cooling water (cooling water temperature).

Spark plugs 9A and 9B provided for each cylinder of the engine 1
The point signals distributed by the distributor 10 are applied to 9C and 9D. Distributor 10 is igniter 11
Is distributed to each of the spark plugs 9A to 9D in synchronization with the crank angle of the engine 1.
The ignition timing of each of the ignition plugs 9A to 9D is determined by the high voltage output timing from the igniter 11.

The distributor 10 has a rotation speed sensor 25 as an engine rotation speed detecting means for detecting the rotation speed (engine rotation speed) NE of the engine 1 from the rotation of the rotor (not shown), and the crank angle of the engine 1 according to the rotation of the rotor. The cylinder discriminating sensors 26 for detecting the change of the cylinder at a predetermined rate are attached. In this embodiment, assuming that the engine 1 makes two revolutions per stroke, the cylinder discrimination sensor 26
The crank angle is detected at the rate of 360 ゜ CA.

A transmission (not shown), which is drivingly connected to the engine 1, is provided with a vehicle speed sensor 27 for detecting a vehicle speed.

The injectors 6A to 6D and the igniter 11 are electrically connected to an electronic control unit (hereinafter simply referred to as "ECU") 30, and the drive timing of the ECU 30 is controlled by the operation of the ECU 30. This ECU 30 is an average measurement value calculation means,
It constitutes steady intake flow rate calculating means, smoothing theoretical value calculating means, final intake flow rate calculating means, and engine control amount calculating means. Further, a throttle opening sensor 21, an air flow meter 22, an oxygen sensor 23, a water temperature sensor 24, a rotation speed sensor 25, a cylinder discrimination sensor 26, and a vehicle speed sensor 27 are connected to the ECU 30. Then, the ECU 30 is based on the output signals from the air flow meter 22 and the sensors 21, 23 to 27,
The injectors 6A to 6D and the igniter 11 are suitably controlled.

Next, the configuration of the ECU 30 will be described with reference to the block diagram of FIG. The ECU 30 includes a central processing unit (CPU) 31, a read-only memory (ROM) 32 in which a predetermined control program and the like are stored in advance, a random access memory (RAM) 33 in which a calculation result of the CPU 31 and the like are temporarily stored, and data stored in advance. It is configured as a logical operation circuit in which a backup RAM 34 and the like to be stored, and these units, an external input circuit 35, an external output circuit 36 and the like are connected by a bus 37.

The external input circuit 35 includes the throttle opening sensor described above.
21, air flow meter 22, oxygen sensor 23, water temperature sensor 2
4, rotation speed sensor 25, cylinder discrimination sensor 26 and vehicle speed sensor 2
7 etc. are connected respectively. Then, the CPU 31 sends the air flow meter 22 and the sensors 21 and 2 through the external input circuit 35.
Read the output signals from 3 to 27 as input values.

Further, the CPU 31 outputs the external output circuit 3 based on these input values.
The injectors 6A to 6D connected to 6 and the igniter 11 are suitably controlled.

Next, the fuel injection control executed by the ECU 30 will be described with reference to the flowchart of FIG.
Note that the routine of this flowchart is executed by a periodic interruption every predetermined time.

When the processing shifts to this routine, first, at step 101
In step (1), the engine speed NE and the intake air flow rate GA, which is an actual intake air flow rate measurement value, are taken in based on the values detected by the engine speed sensor 25 and the air flow meter 22. Then, in step 102, a unit intake flow rate GN per one revolution of the engine 1 is calculated from the taken engine speed NE and intake flow rate GA.

Next, in step 103, a smoothing process is performed so that the unit intake air flow rate GN is gradually changed according to the following equation (1), and the processing result is used as a smoothed measured value GNSM1 in the current processing cycle.

GNSM1 ← GNSM0 + (GN−GNSM0) * KG1 (1) where GNSM0 is a smoothing measurement value in the previous processing cycle, and KG1 is a smoothing coefficient predetermined to suppress pulsation of the unit intake flow rate GN. It is.

In step 104, the engine speed is determined based on the detection values of the speed sensor 25 and the throttle opening sensor 21.
NE and throttle opening TA are taken in. Then, in step 105, a predetermined theoretical steady-state intake air flow rate GNTA is calculated from the taken engine speed NE and throttle opening degree TA. This steady intake air flow rate GNTA
As shown in the figure, the engine speed NE and throttle opening TA
Is obtained according to a predetermined three-dimensional map using

Next, in step 106, smoothing processing is performed so that the steady intake air flow rate GNTA is gradually changed according to the following equation (2), and the processing result is set as a smoothed logical value GNCRT1 in the current processing cycle.

GNCRT1 ← GNCRT0 + (GNT−GNCRT0) * KG2 (2) Here, GNCRT0 is a smoothing theoretical value in the previous processing cycle, and KG2 is a predetermined smoothing coefficient. Further, the smoothed measurement value GNSM1 needs a filter that does not cause flicker (periodic variation) in the unit intake flow rate GN. Therefore, as a filter for the smoothed theoretical value GNCRT1, the smoothed measured value GNSM
An averaging factor KG2 is selected such that the averaging value GNCRT1 is approximately equal to 1.

Then, in step 107, the final intake flow rate (final intake flow rate) GNEND is calculated according to the following equation (3), and the result is used as the final intake flow rate GN in the current processing cycle.
END.

GNEND ← GNSM1 + (GNTA−GNCRT1) (3) That is, the difference between the steady intake flow rate GNTA and the smoothed theoretical value GNCRT1 is added to the smoothed measured value GNSM1 to obtain the final intake flow rate GNEND.

Then, in step 108, the final intake flow rate GNEND
Is multiplied by a previously obtained injection constant KINJ to obtain a basic injection amount TP.

Finally, in step 109, the basic injection amount TP
Then, a value obtained by multiplying the previously obtained various correction coefficients FK is determined as the fuel injection amount TAU, and the subsequent processing is temporarily terminated.

Here, the calculation of the final intake air flow rate GNEND at the time of operation transition in which the throttle opening TA changes will be described with reference to the time chart of FIG.

Now, as shown in FIG. 6 (a), when the throttle opening TA sharply increases and changes at time t1, the amount of air actually taken into each cylinder is accordingly also shown in FIG. 6 (b). Change rapidly.

In such an operation transition when the throttle opening TA changes, the unit intake air flow rate GN obtained based on the intake air flow rate GA which is the measurement value of the air flow meter 22, as shown in FIG. Fluctuation (periodic fluctuation) may occur due to intake pulsation in the passage 2 or output fluctuation of the air flow meter 22. Then, even if the unit intake flow rate GN fluctuates, as shown in FIGS. 6 (b) and 6 (c), the smoothed measured value GNSM obtained by the smoothing process of the value is taken into each cylinder. It changes gradually and smoothly with a slight delay to the change in air volume.

On the other hand, the steady intake air flow rate GNTA obtained from the engine speed NE and the throttle opening TA rapidly increases to approximate the change in the amount of intake air to each cylinder as shown in FIG. 6 (d). Change. The smoothed theoretical value GNCRT obtained by smoothing the steady intake air flow rate GNTA is slightly delayed from the rise of the intake air amount to each cylinder as shown in FIGS. 6 (b) and 6 (d). It changes gradually and smoothly.

Here, as described above, in step 106 of the flowchart in FIG. 4, the smoothed measured value GNSM is converted to the smoothed theoretical value GNCRT.
The smoothing coefficient KG2 is selected so as to be approximately equal to. In addition, the portion shown by oblique lines in FIG. 6 (d) is the difference between the steady intake air flow rate GNTA and the smoothed theoretical value GNCRT.

Then, as shown in FIG. 6 (e), the final intake flow rate GN
END is the difference between the steady intake air flow rate GNTA and the smoothed theoretical value GNCRT,
Obtained as the value added to the smoothed measurement value GNSM. Therefore, a final intake flow rate GNEND is obtained in which fluttering caused by intake pulsation in the intake passage 2 and output fluctuation of the air flow meter 22 is eliminated.

As described above, according to the control device of this embodiment, even if the actual measured value of the air flow meter 22 fluctuates due to the pulsation of the intake air in the intake passage 2 or the like, the unit intake flow rate GN is determined based on the measured value. Is annealed. Therefore,
It is possible to obtain a smoothed measured value GNSM that changes gradually and smoothly by removing the influence of intake pulsation and the like.

If there is a difference in the amount of intake air leaking into each cylinder due to the product tolerance of each of the throttle valves 8A to 8D and its aging, etc.
The GNSM is a value that changes according to the difference in the amount of intake air leakage and the like. On the other hand, throttle opening TA and engine speed NE
And the theoretical steady-state intake air flow rate GNTA determined from the relationship
The value of the difference from the simulated theoretical value GNCRT obtained by the averaging process does not change in accordance with the difference in the amount of intake air leakage or the like. Therefore, the steady intake air flow rate GNTA and the smoothed theoretical value GN
The final intake air flow rate GNEND obtained by adding the difference from the CRT and the smoothing measurement value GNSM is a value reflecting the intake air leakage amount. In other words, when the actual air intake amount into each cylinder is different from the theoretical steady intake air flow rate GNTA due to the product tolerance of each throttle valve 8A to 8D or its aging, the final Intake flow rate GNEND, actual intake flow rate G
A, the steady intake air flow rate GNTA does not become equal to each other, and the final intake air flow rate GNEND reflecting the difference in intake air leakage amount
Can be obtained.

In other words, it is possible to always obtain an appropriate final intake flow rate GNEND in accordance with the product variation of the throttle valves 8A to 8D and the difference in the intake flow rate GA due to the aging thereof. Then, an appropriate fuel injection amount TAU can always be obtained based on the appropriate final intake air flow rate GNEND.

What is added to the smoothed measurement value GNSM is the difference between the steady intake air flow rate GNTA and its smoothed theoretical value GNCRT. Therefore, even if the theoretical steady-state intake flow rate GNTA is determined by another map by mistake, that is, by incorrect matching, the error can be canceled and a sufficiently usable final intake flow rate GNEND can be determined. .

In addition, in this embodiment, the throttle valves 8A to 8D are provided for each cylinder downstream of the surge tank 5. For this reason, when the engine 1 is operating, the amount of air taken into each cylinder becomes substantially equal to the actual intake flow rate passing through each of the throttle valves 8A to 8D.
There is no first-order lag in the intake air flow rate GA measured by the measurement. For this reason, during the normal operation in which the opening change of the throttle valves 8A to 8D is small, the intake flow rate GA measured by the air flow meter 22 is used as the basic injection amount T for obtaining the fuel injection amount TAU.
It can be used as it is for the calculation of P.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. The general configuration of the gasoline engine system and the configuration of its ECU applied in this embodiment are substantially the same as those of the first embodiment, and will be described with reference to the configuration diagrams of FIGS. I do.
In this embodiment, only the control processing mainly executed by the ECU 30 will be described. The only difference from the configuration is that the air flow meter 22 of the first embodiment is a movable vane type, whereas the air flow meter 22 of this embodiment is a hot wire type.

In the case of a gasoline engine system using a hot-wire type air flow meter 22, it is also measured that there is intake air at the time of blowback (backflow) in intake pulsation in the intake passage 2. Therefore, the intake flow rate GA, which is a measurement value of the air flow meter 22, is a value larger than the actual intake flow rate.
As a result, the fuel injection amount calculated based on the intake air flow rate GA
TAU also becomes a large value, and the air-fuel ratio becomes over-rich.
For this reason, in general, a maximum guard is measured for the intake flow rate GA, which is a measured value of the air flow meter 22, and the basic injection amount TP calculated based on the intake flow rate GA, to prevent over-rich. However, when the vehicle moves to a high altitude, the air density becomes low. Therefore, if the maximum guard of the intake air flow rate GA and the basic injection amount TP is kept at a low altitude, the air becomes rich again.

Therefore, in this embodiment, an atmospheric pressure correction control that can lower the maximum guard of the intake air flow rate GA and the basic injection amount TP according to a change in the atmospheric pressure when moving to a high altitude will be described.

FIG. 7 is a flowchart for explaining the processing of the atmospheric pressure correction control executed by the ECU 30. Note that the routine of this flowchart is executed by a periodic interruption every predetermined time.

When the processing shifts to this routine, first, step 201
In step (1), the engine speed NE and the intake air flow rate GA, which is an actual intake air flow rate measurement value, are taken in based on the values detected by the engine speed sensor 25 and the air flow meter 22. Then, in step 202, a unit intake flow rate GN per one revolution of the engine 1 is calculated based on the taken engine speed NE and intake flow rate GA.

Next, in step 203, the unit intake flow rate GN is gradually changed according to the following equation (1) using the smoothing measurement value GNSM0 and the smoothing coefficient KG1 in the previous processing cycle, as in the first embodiment. Is performed, and the processing result is used as a measured average value GNSM1 in the current processing cycle.

GNSM1 ← GNSM0 + (GN−GNSM0) * KG1 (1) Also, in step 204, the engine speed is determined based on the values detected by the speed sensor 25 and the throttle opening sensor 21.
NE and throttle opening TA are taken in. Then, in step 205, a predetermined theoretical steady-state intake air flow rate GNTA is calculated from the taken engine speed NE and throttle opening degree TA. This steady intake air flow rate GNTA is, as in the first embodiment, the engine speed as shown in FIG.
It is obtained according to a predetermined three-dimensional map using NE and throttle opening TA as parameters.

Next, in step 206, as in the first embodiment, the steady intake air flow rate GNTA is gradually changed according to the following equation (2) using the smoothing theoretical value GNCRT0 and the smoothing coefficient KG2 in the previous processing cycle. So that
The result is averaged theoretical value GNCRT1 in this processing cycle.
And

GNCRT1 ← GNCRT0 + (GNT−GNCRT0) * KG2 (2) Then, in step 207, the smoothed measured value GNSM1 in the current processing cycle is compared with the smoothed theoretical value GNCRT1 according to the following equation (4). The percentage of the difference between the ratio and 1 is obtained and defined as the smoothed difference ratio ΔGNP.

ΔGNP ← {(GNSM1 / GNCRT1) −1} * 100 (4) Next, in step 208, as shown in FIG.
In the relationship between the smoothing ratio difference ΔGNP and the intake air flow rate GA, it is determined whether the current state is in the A region or not. That is, step
Based on the engine speed NE taken in at 204 and the steady intake air flow rate GNTA obtained at step 205, if they satisfy the following equations (5) and (6), it is determined to be in the A region. .

1000 <NE <2000 (rpm) (5) 0.2 <GNTA <0.4 (g / rev) (6) Then, the engine speed NE and the steady intake air flow rate GNTA are A.
If it is an area, in step 209, the area flag FAORB is reset to “0” and the process proceeds to step 212. If the engine speed NE and the steady intake air flow rate GNTA are not in the A range, the process proceeds to step 210.

In step 210, it is determined whether or not the current condition is the region B in the relationship between the smoothing ratio difference ΔGNP and the intake air flow rate GA shown in FIG. That is, similarly to step 208, based on the engine speed NE and the steady intake air flow rate GNTA, if they satisfy the following expressions (7) and (8), it is determined that the region is the B region.

2500 <NE <4000 (rpm) (7) 0.5 <GNTA <0.8 (g / rev) (8) Then, the engine speed NE and the steady intake air flow rate GNTA are B.
If it is an area, in step 211, the area flag F
AORB is set to “1” and the process proceeds to step 212.
If the engine speed NE and the steady intake air flow rate GNTA are not in the B region, the subsequent processing is temporarily terminated.

Shift from step 209 or step 211 to step 21
In 2, it is determined whether or not the area flag FAORB is “1”. That is, it is determined whether or not the current state is the area B.

If the area flag FAORB is “1”, that is, if the current state is the area B, it is determined in step 213 whether or not the smoothing ratio difference ΔGNP is “3% or less”.

If the annealing ratio difference ΔGNP is not “3% or less”,
In step 214, “0.01” is added to the atmospheric pressure correction coefficient KPA, and the result is set as a new atmospheric pressure correction coefficient KPA. If the smoothing difference ratio ΔGNP is “3% or less”, it is determined in step 215 whether the smoothing difference ratio ΔGNP is “−3% or more”.

If the annealing ratio difference ΔGNP is not “−3% or more”, in step 216, the atmospheric pressure correction coefficient KPA is set to “0.
After subtracting “01” and setting the result as a new atmospheric pressure correction coefficient KPA, the process proceeds to step 217. Also, the annealing ratio difference rate ΔG
If NP is “−3% or more”, step as it is
Move to 217.

At step 217 after shifting from step 214, step 215 or step 216, the newly obtained atmospheric pressure correction coefficient KPA is set to the atmospheric pressure correction coefficient guard KPAMI as the lower limit value.
It is determined whether it is smaller than N.

The atmospheric pressure correction coefficient KPA is equal to the atmospheric pressure correction coefficient guard K.
If smaller than PAMIN, in step 218, the atmospheric pressure correction coefficient guard KPAMIN is set as the atmospheric pressure correction coefficient KPA, and the subsequent processing is temporarily terminated. If the atmospheric pressure correction coefficient KPA is not smaller than the atmospheric pressure correction coefficient guard KPAMIN, the subsequent processing is temporarily terminated. That is, when the current state is the B region, the smoothing ratio difference ΔGN
It is determined whether or not P is within ± 3%, and the atmospheric pressure correction coefficient KPA is updated up to the atmospheric pressure correction coefficient guard KPAMIN according to the result.

On the other hand, if the area flag FAORB is “0” in step 212, that is, if the current state is the area A, step 21
At 9, it is determined whether or not the smoothing ratio difference ΔGNP is “3% or less”.

If the annealing ratio difference ΔGNP is not “3% or less”,
At step 220, “0.02” is added to the guarded atmospheric pressure correction coefficient KPAL, and the result is set as a new guarded atmospheric pressure correction coefficient KPAL. If the smoothing difference ratio ΔGNP is “3% or less”, in step 221 the smoothing difference ratio ΔGNP is “−3% or more”.
Is determined.

If the annealing ratio difference ΔGNP is not “−3% or more”, in step 222, the guarded atmospheric pressure correction coefficient KPA
After subtracting “0.02” from L and setting the result as a new atmospheric pressure correction coefficient with guard KPAL, the process proceeds to step 223.
If the smoothing difference ratio ΔGNP is “−3% or more”, the process directly proceeds to step 223.

At step 223 after shifting from step 220, step 221 or step 222, the guarded atmospheric pressure correction coefficient K
“0.03” is subtracted from PAL, and the result is referred to in step 217.
New barometric pressure correction factor guard used for comparison with
After setting KPAMIN, the subsequent processing ends once. That is, when the current state is the area A, the smoothing ratio difference ΔGN
It is determined whether or not P is within ± 3%, and the atmospheric pressure correction coefficient guard KPAMIN is set according to the result.

As described above, according to the control device of this embodiment, it is determined whether the current state is one of the two areas, the area A and the area B. ,
The atmospheric pressure correction coefficient KPA is set.

Next, the fuel injection control executed using the atmospheric pressure correction coefficient KPA set as described above will be described with reference to the flowchart of FIG. In the fuel injection control of this embodiment, a countermeasure for over-enrichment due to intake pulsation is taken. Note that the routine of this flowchart is EC
It is executed by U30, and is executed by a periodic interruption every predetermined time.

When the process proceeds to this routine, first, at step 301
, The engine speed NE and the intake air flow rate GA are acquired based on the detection values of the engine speed sensor 25 and the air flow meter 22, respectively. Then, in step 302, the unit intake flow rate is calculated based on the taken engine speed NE and intake flow rate GA.
Calculate GN.

Next, in step 303, as in the first embodiment, the unit intake air flow rate GN is smoothed according to the following equation (1) using the smoothing measurement value GNSM0 and the smoothing coefficient KG1 in the previous processing cycle. Then, the processing result is used as the smoothed measurement value GNSM1 in the current processing cycle.

GNSM1 ← GNSM0 + (GN−GNSM0) * KG1 (1) Also, in step 304, the engine speed is determined based on the values detected by the speed sensor 25 and the throttle opening sensor 21.
NE and throttle opening TA are taken in. Then, in step 305, the engine speed NE and the throttle opening TA are previously determined as parameters from the taken engine speed NE and throttle opening TA as shown in FIG. The steady intake air flow rate GNTA is obtained according to the map provided.

Next, in step 306, as in the first embodiment, the steady intake air flow rate GNTA is smoothed according to the following equation (2) using the smoothed theoretical value GNCRT0 and the smoothed coefficient KG2 in the previous processing cycle. Then, the processing result is set as a smoothed theoretical value GNCRT1 in the current processing cycle.

GNCRT1 ← GNCRT0 + (GNT−GNCRT0) × KG2 (2) In step 307, as in the first embodiment, the final intake flow rate GNEND is calculated according to the following equation (3), and the result is used as the new final intake air. The flow rate is GNEND.

GNEND ← GNSM1 + (GNTA−GNCRT1) (3) Subsequently, in step 308, a predetermined theoretical steady-state final intake air flow rate GNMAXB is calculated from the engine speed NE. This steady maximum intake flow rate GNMAXB is obtained according to a map as shown in FIG.

Next, at step 309, the obtained steady maximum intake flow rate GNMAXB is multiplied by the atmospheric pressure correction coefficient KPA set in the flowchart of FIG. 7, and the result is set as the corrected maximum intake flow rate GNMAX. As a result, the corrected maximum intake flow rate GNMAX
Is a value corresponding to the magnitude of the atmospheric pressure. That is, the intake flow rate is corrected for the atmospheric pressure.

Then, at step 310, it is determined whether or not the previously obtained final intake air flow rate GNEND is larger than the corrected maximum intake air flow rate GNMAX. Here, if the final intake air flow rate GNEND is not larger than the corrected maximum intake air flow rate GNMAX, the process directly proceeds to step 312. If the final intake flow rate GNEND is larger than the corrected maximum intake flow rate GNMAX, in step 311, the corrected maximum intake flow rate GNMAX is set to the final intake flow rate GNEND, and then the process proceeds to step 312.

Move from step 310 or 311 to step 31
In 2, the value obtained by multiplying the final intake flow rate GNEND by the injection constant KINJ is obtained as the basic injection amount TP.

Finally, at step 313, the basic injection amount TP
Is multiplied by a correction coefficient FK to obtain a combustion injection amount TAU, and the subsequent processing is temporarily terminated.

As described above, according to the control device of this embodiment, even if the actual measured value of the air flow meter 22 fluctuates due to the pulsation of the intake air in the intake passage 2 or the like, the unit intake flow rate GN based on the measured value is obtained. Is annealed. Therefore,
It is possible to obtain a smoothed measured value GNSM that changes gradually and smoothly by removing the influence of intake pulsation and the like.

If there is a difference in the amount of intake air leaking into each cylinder due to the product tolerance of each of the throttle valves 8A to 8D and its aging, etc.
The GNSM is a value that changes according to the difference in the amount of intake air leakage and the like. On the other hand, throttle opening TA and engine speed NE
And the theoretical steady-state intake air flow rate GNTA determined from the relationship
The value of the difference from the simulated theoretical value GNCRT obtained by the averaging process does not change in accordance with the difference in the amount of intake air leakage or the like. Therefore, the steady intake air flow rate GNTA and the smoothed theoretical value GN
The final intake air flow rate GNEND obtained by adding the difference from the CRT and the smoothing measurement value GNSM is a value reflecting the intake air leakage amount. In other words, it is possible to always obtain an appropriate final intake flow rate GNEND in accordance with the product variation of the throttle valves 8A to 8D and the difference in the intake flow rate GA due to the aging thereof. Then, an appropriate fuel injection amount TAU can always be obtained based on the appropriate final intake air flow rate GNEND.

Moreover, according to the control device of this embodiment, it is possible to obtain an appropriate final intake air flow rate GNEND that has been atmospherically corrected by the atmospheric pressure correction coefficient KPA without providing a special atmospheric pressure sensor. Therefore, an appropriate fuel injection amount TAU according to the change in the atmospheric pressure can be obtained.

That is, it is possible to obtain an appropriate final intake flow rate GNEND corrected for the atmospheric pressure in accordance with the product variation of the throttle valves 8A to 8D and the difference in the intake flow rate GA due to the aging thereof. Then, an appropriate fuel injection amount TAU can always be obtained based on the appropriate final intake air flow rate GNEND.

In FIG. 8, a straight line L1 indicates a change in the smoothing ratio difference rate ΔGNP at a high altitude. Smoothing ratio difference ΔGNP at high altitude
Is substantially constant irrespective of the magnitude of the intake air flow rate GA, and the smoothing ratio difference ΔGNP is substantially the same in both the region A and the region B.

On the other hand, in FIG. 8, a curve L2 indicates a change in the smoothing ratio difference ΔGNP in a case where a large amount of snow enters the air cleaner 4 due to a follow-up running or a snowstorm running in a snowy area and the cleaner element is clogged. Is shown. It can be seen that the change in the smoothing ratio difference ΔGNP in the clogged state is close to “0” when the intake flow rate GA is small, and gradually decreases to the minus side as the intake flow rate GA increases. A
That is, the average ratio difference ΔGNP differs between the region and the region B. That is, even if the throttle valves 8A to 8D are opened, the pressure loss increases due to the clogging of snow in the air cleaner 4, and it becomes difficult for the engine 1 to take air.
For this reason, the theoretical steady intake air flow obtained from the actual intake air flow GA and the engine speed NE and the throttle opening TA
There is a big difference from GNTA.

Therefore, according to the control device of this embodiment, when the air cleaner 4 is clogged with snow, it is determined that the atmospheric pressure is low despite traveling on level ground, and the atmospheric pressure correction coefficient KPA is updated. Will be. Then, when the engine 1 enters a dead soak or hot soak state after the atmospheric pressure correction coefficient KPA is updated in this manner, the snow clogged in the air cleaner 4 melts, and the pressure loss due to the snow is eliminated.

Here, when acceleration or the like is performed in the engine speed region accompanied by intake pulsation with blow-back, that is, the throttle opening TA
When the operating transition changes, the corrected maximum intake air flow rate GNMAX is set to a low level based on the atmospheric pressure correction coefficient KPA obtained at the time of snow clogging. As a result, the air-fuel ratio becomes over-lean, which may cause misfire, poor drivability and the like.

Therefore, in order to prevent this, in the control device of this embodiment, a check area is set in the area A. That is, the atmospheric pressure correction coefficient guard KPAMIN is set in the region A. Then, the annealing ratio difference Δ between the A region and the B region
Only when the GNP becomes low, the atmospheric pressure is determined to be low. Then, the nominal ratio difference rate Δ in the B region
When the GNP is low, the above-described problem is eliminated by updating the atmospheric pressure correction coefficient KPA to a value in the A region.

That is, as shown in FIG. 11, an atmospheric pressure correction coefficient with guard KPAL with a slightly lower accuracy is created in the area A, and the atmospheric pressure correction coefficient KPA is updated with high accuracy in the area B.

Note that the present invention is not limited to the above embodiments, and may be implemented as follows by appropriately updating a part of the configuration without departing from the spirit of the invention.

(1) In each of the above embodiments, the fuel injection amount TAU is embodied as the engine control amount obtained using the final intake air flow rate GNEND. However, the ignition timing is used as the engine control amount obtained using the final intake air flow rate GNEND. It may be embodied.

(2) In each of the embodiments described above, the movable vane type or hot wire type air flow meter 22 is used as the intake flow rate measuring means. Alternatively, a Karman vortex type air flow meter may be used.

(3) In the above embodiments, the engine is embodied as a four-cylinder engine, but may be embodied as an engine having a different number of cylinders.

[Effects of the Invention] As described above in detail, according to the present invention, the average measured value of the intake air flow rate is smoothed,
The final intake flow rate is obtained by adding the difference between the theoretical steady intake flow rate obtained from the relationship between the throttle opening and the engine speed and the smoothed theoretical value obtained by smoothing the steady intake flow rate, Since the engine control amount is calculated based on the final intake flow rate, an appropriate intake flow rate can always be obtained according to the difference in intake flow rate due to the product tolerance of the throttle valve and its aging. An excellent effect is obtained that an appropriate engine control amount related to the operation of the internal combustion engine can always be obtained based on the flow rate.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of the present invention, and FIGS.
FIG. 1 is a diagram according to a first embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a gasoline engine system to which a control device for an internal combustion engine is applied, and FIG. 3 is a block diagram showing an electrical configuration thereof. FIG. 4 is a flowchart for explaining processing of fuel injection amount control executed by the control device;
FIG. 5 is a three-dimensional map using the throttle opening and the engine speed as parameters for obtaining a steady intake air flow rate, and FIG.
The figure is a time chart for explaining the calculation of the final intake flow rate during the operation transition. 7 to 11 are diagrams according to a second embodiment of the present invention, and FIG. 7 is a flowchart illustrating a process of an atmospheric pressure correction control executed by a control device of the internal combustion engine. FIG. 8 is a diagram for explaining the A region and the B region in the relationship between the intake air flow rate and the smoothing ratio difference rate;
FIG. 9 is a flowchart for explaining a process of fuel injection amount control similarly executed by the control device, FIG. 10 is a map showing a relationship between a steady maximum intake air flow rate and an engine speed,
FIG. 11 is a diagram for explaining the relationship between the atmospheric pressure correction coefficient and the intake flow rate. In the figure, M1 is an intake passage, M2 is a surge tank, M3 is a throttle valve, M4 is an internal combustion engine, M5 is a throttle opening detecting means, M6 is an engine speed detecting means, M7 is an intake flow rate measuring means,
M8 is a smoothed measurement value calculating means, M9 is a steady intake flow rate calculating means, M10 is a smoothed theoretical value calculating means, M11 is a final intake flow rate calculating means, M12 is an engine control amount calculating means, 1 is an engine as an internal combustion engine, 2 is the intake passage, 5 is the surge tank, 8A ~
8D is a throttle valve, 21 is a throttle opening sensor as a throttle opening detecting means, 22 is an air flow meter as an intake flow rate measuring means, 25 is a rotation speed sensor as an engine speed detecting means, and 30 is a smoothed measurement value calculation. The ECU constitutes means, steady intake flow rate calculating means, smoothing theoretical value calculating means, final intake flow rate calculating means, and engine control amount calculating means.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Makoto Gemiya 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Kyoji Kaji 1-1 1-1 Showacho Kariya City, Aichi Prefecture Japan Denso Co., Ltd. (56) References JP-A-59-63330 (JP, A) JP-A-61-43234 (JP, A) JP-A-61-157730 (JP, A) JP-A-62-32233 (JP, A) JP-A-62-253942 (JP, A) JP-A-2-42160 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02D 41/00-41/40 F02D 45/00

Claims (1)

(57) [Claims] An independent throttle type internal combustion engine having a throttle valve for each cylinder downstream of a surge tank provided in the middle of an intake passage, wherein a throttle opening for detecting an opening of the throttle valve is provided. Degree detection means, engine speed detection means for detecting the rotation speed of the internal combustion engine, intake flow rate measurement means for measuring the actual intake flow rate passing through the intake passage, and gradually measuring the actual intake flow rate value Smoothing measurement value calculating means for calculating a smoothing measurement value by performing a smoothing process so as to change; a theoretical value according to a predetermined relationship using the opening degree of the throttle valve and the rotation speed of the internal combustion engine as parameters. A steady-state intake flow rate calculating means for calculating a steady-state intake flow rate, and the theoretical steady-state intake flow rate is set to be equal to the smoothed measured value when a predetermined relationship is set. A smoothing theoretical value calculating means for calculating a smoothing theoretical value by performing a smoothing process so as to gradually change, and the difference between the theoretical steady intake air flow rate and the smoothing theoretical value is converted to the smoothing measured value. And a final intake flow rate calculating means for calculating a final intake flow rate, and an engine control amount calculating means for calculating an engine control amount based on the calculated final intake flow rate. Control device for internal combustion engine.