WO2014024609A1

WO2014024609A1 - Control device and control method for internal combustion engine

Info

Publication number: WO2014024609A1
Application number: PCT/JP2013/068340
Authority: WO
Inventors: 露木　毅
Original assignee: 日産自動車株式会社
Priority date: 2012-08-07
Filing date: 2013-07-04
Publication date: 2014-02-13

Abstract

When the actual EGR amount deviates from a target EGR amount, it is determined that a change in the pressure loss has occurred in the intake/discharge system of an internal combustion engine (1), and the aperture area of an EGR control valve (21), which corresponds to the EGR rate, is corrected such that the actual EGR amount matches the target EGR amount. For example, an aperture area correction value, which is the flow volume ratio between the target EGR amount corresponding to the target EGR rate and the actual EGR amount corresponding to the actual EGR rate, is calculated, and the slope of a characteristic line indicating the correlation between the EGR rate and the aperture area of the EGR control valve (21) is corrected on the basis of the aperture area correction value. Thus, the EGR amount recirculated to the intake passage (2) can be controlled precisely.

Description

Control device and control method for internal combustion engine

The present invention relates to a control device and a control method for an internal combustion engine that recirculates part of exhaust gas upstream of a supercharger.

For example, in Patent Document 1, an EGR gas partial pressure estimated value is calculated using an air partial pressure estimated value and an intake pipe internal pressure, and the EGR gas partial pressure estimated value is calculated based on a throttle opening and an engine speed. An EGR control device that performs feedback control so as to be equal to a target value for EGR gas partial pressure control is disclosed.

In this patent document 1, when EGR is not carried out, the actual volume efficiency that is the actual volume efficiency and the reference volume efficiency that is the volume efficiency in the reference state are calculated. A technique for improving the estimation accuracy of the EGR gas partial pressure estimation value by learning a learning correction value that is a difference between the two and calculating an air partial pressure estimation value using the learning correction value is disclosed.

The actual volume efficiency is calculated based on the engine speed, the intake air amount, the gas temperature in the intake pipe, the pressure in the intake pipe, the exhaust amount per cylinder, and the gas constant. The reference volumetric efficiency is an initial setting value that does not take into account individual differences or changes with time that the engine has individually, and is calculated based on the engine speed.

However, this Patent Document 1 performs feedback control so that the EGR gas partial pressure estimated value calculated from the air partial pressure estimated value and the intake pipe internal pressure becomes the EGR gas partial pressure control target value. For each (operating point), an EGR gas partial pressure estimate must be calculated. That is, there is a problem that the air partial pressure estimated value must be corrected with the learning correction value for every operating condition.

Further, when the EGR amount is controlled using the pressure as an index as in Patent Document 1, since the actual values of the EGR gas partial pressure and the air partial pressure are easily affected by the air temperature and the EGR gas temperature, an error in the EGR control. There is a problem that it tends to be a factor.

JP 2000-220532 A

Accordingly, the present invention provides a control device for an internal combustion engine that recirculates a part of the exhaust gas as EGR from the upstream side of the turbocharger, and when the actual EGR amount deviates from the target EGR amount, It is determined that a change in pressure loss has occurred in the exhaust system, and the opening area of the EGR control valve corresponding to the EGR rate is corrected so that the actual EGR amount matches the target EGR amount.

According to the present invention, since the opening area of the EGR control valve can be corrected so that the actual EGR amount follows the target EGR amount, the EGR amount recirculated to the intake passage can be accurately controlled.

1 is a system diagram showing the overall configuration of a control device for an internal combustion engine according to the present invention. Explanatory drawing which showed typically the control content in 1st Example. The block diagram which shows the calculation content of the opening degree correction | amendment of an EGR control valve. The block diagram which shows the calculation content of the opening degree correction | amendment of an EGR control valve. Explanatory drawing which showed typically the control content in 2nd Example. Explanatory drawing which showed typically the control content in 2nd Example. Explanatory drawing which showed typically the control content in 2nd Example.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a system diagram showing an overall configuration of an internal combustion engine 1 to which the present invention is applied.

The internal combustion engine 1 is mounted on a vehicle such as an automobile as a drive source, and an intake passage 2 and an exhaust passage 3 are connected to each other. A throttle valve 5 is provided in the intake passage 2 connected to the internal combustion engine 1 via the intake manifold 4, and an air flow meter 6 and an air cleaner 7 for detecting the intake air amount are provided upstream thereof. Yes. An exhaust catalyst 9 such as a three-way catalyst is provided for exhaust purification in the exhaust passage 3 connected to the internal combustion engine 1 via the exhaust manifold 8.

The internal combustion engine 1 has a turbocharger 10 that is coaxially provided with a compressor 11 disposed in the intake passage 2 and a turbine 12 disposed in the exhaust passage 3. The compressor 11 is located upstream of the throttle valve 5 and is located downstream of the air flow meter 6. The turbine 12 is located on the upstream side of the exhaust catalyst 9. In addition, 13 in FIG. 1 is an intercooler provided on the downstream side of the throttle valve 5. The intercooler 13 may be provided between the throttle valve 5 and the compressor 11.

A recirculation passage 14 that bypasses the compressor 11 and connects the upstream side and the downstream side of the compressor 11 is connected to the intake passage 2. In the recirculation passage 14, the recirculation is controlled so that the air in the intake passage 2 between the compressor 11 and the throttle valve 5 is returned to the upstream side of the compressor 11 when the throttle valve 5 is closed. A ration valve 15 is interposed.

The exhaust passage 3 is connected to an exhaust bypass passage 16 that bypasses the turbine 12 and connects the upstream side and the downstream side of the turbine 12. In the exhaust bypass passage 16, a waste gate valve 17 that controls the exhaust flow rate in the exhaust bypass passage 16 is interposed.

The internal combustion engine 1 can perform exhaust gas recirculation (EGR), and an EGR passage 20 is provided between the exhaust passage 3 and the intake passage 2. One end of the EGR passage 20 is connected to the exhaust passage 3 at a position downstream of the exhaust catalyst 9, and the other end is connected to the intake passage 2 at a position downstream of the air cleaner 7 and upstream of the compressor 11. . An EGR control valve 21 and an EGR cooler 22 are interposed in the EGR passage 20. The opening degree of the EGR control valve 21 is controlled by the control unit 25 so that a predetermined EGR rate corresponding to the operating condition is obtained.

The control unit 25 detects the intake pressure P1 in the intake passage 2 on the upstream side of the compressor 11 and the crank angle sensor 26 that detects the crank angle of the crankshaft (not shown), in addition to the detection signal of the air flow meter 6 described above. The intake pressure sensor 27, the exhaust pressure sensor 28 for detecting the exhaust pressure P2 downstream of the EGR cooler 22 in the EGR passage 20 connected to the exhaust passage 3 downstream of the exhaust catalyst 9, and the amount of depression of an accelerator pedal (not shown). Detection signals of sensors such as the accelerator opening sensor 29 to be detected are input. The exhaust pressure sensor 28 may detect the exhaust pressure in the exhaust passage on the downstream side of the exhaust catalyst 9.

Based on these detection signals, the control unit 25 controls the ignition timing and air-fuel ratio of the internal combustion engine 1 and controls the opening degree of the EGR control valve 21 to control the opening of the intake passage 2 from the exhaust passage 3. Exhaust gas recirculation control (EGR control) for recirculating part of the exhaust gas is performed. The opening degree of the throttle valve 5, the recirculation valve 15, and the waste gate valve 17 is also controlled by the control unit 25. The recirculation valve 15 is not controlled to be opened and closed by the control unit 25, and a so-called check valve that opens only when the pressure on the downstream side of the compressor 11 exceeds a predetermined pressure can be used. is there.

In the configuration in which EGR is introduced from the upstream side of the compressor 11 of the turbocharger 10 provided in the intake passage 2, EGR is introduced by the pressure difference between the exhaust pressure P2 and the intake pressure P1.

Here, from the relationship based on Bernoulli's theorem, a proportional relationship is established between the intake air amount and the square root of the differential pressure across the EGR control valve 21 (pressure difference between the exhaust pressure P2 and the intake pressure P1). . A proportional relationship is also established between the square root of the differential pressure across the EGR control valve 21 (the difference in pressure between the exhaust pressure P2 and the intake pressure P1) and the EGR amount (exhaust gas recirculation amount). Accordingly, a proportional relationship (constant EGR rate) is also established between the intake air amount and the EGR amount. That is, in the configuration in which a part of the exhaust gas is recirculated to the intake passage 2 using the pressure difference between the intake pressure P1 and the exhaust pressure P2, if the opening degree (opening area) of the EGR control valve 21 is constant, the intake air amount Even if changes, the ratio of the intake air amount and the EGR amount becomes constant, so that the EGR rate becomes constant.

However, when the pressure loss of the intake / exhaust system of the internal combustion engine 1 changes and the differential pressure across the EGR control valve 21 changes, the EGR rate corresponding to the opening degree (opening area) of the EGR control valve 21 changes. The actually measured EGR amount changes with respect to the target EGR amount. Here, the target EGR amount can be obtained, for example, by multiplying the target EGR rate estimated from the opening degree of the EGR control valve 21 by the intake air amount. The actual EGR amount can be calculated from the intake pressure P1, the exhaust pressure P2, and the intake air amount before and after the EGR control valve 21.

For example, even if the opening degree (opening area) of the EGR control valve 21 is constant, if the exhaust system muffler has a hole due to corrosion or the like and the pressure loss is small, the exhaust system pressure loss is small. As a result, the pressure difference becomes smaller and it becomes difficult to introduce EGR, and the actual EGR amount becomes smaller than the target EGR amount. In addition, when water enters the exhaust passage 3 due to traveling on the submerged channel and the pressure loss increases, the pressure difference increases and the EGR is introduced as the exhaust system pressure loss increases. As a result, the actual EGR amount becomes larger than the target EGR amount.

That is, if there is a change in the pressure loss in the intake / exhaust system of the internal combustion engine, the opening degree (opening area) of the EGR control valve 21 corresponding to the EGR rate changes, so the actual EGR amount with respect to the target EGR amount Will diverge.

Therefore, when the actual EGR amount deviates from the target EGR amount, the opening area of the EGR control valve 21 corresponding to the EGR rate is corrected so that the actual EGR amount matches the target EGR amount. The actual EGR amount is made to follow the target EGR amount. That is, the opening area of the EGR control valve 21 corresponding to the EGR rate is corrected according to the deviation of the actual EGR amount with respect to the target EGR amount regardless of the operating conditions.

Since a proportional relationship is established between the EGR rate and the opening area of the EGR control valve 21, for example, if the vertical axis is the opening area of the EGR control valve 21 and the horizontal axis is the EGR rate, the characteristic indicating the correlation between the two is shown. As shown in FIG. 2, the line A passes through the origin and becomes a straight line having a predetermined inclination.

The control unit 25 stores the value of the opening area of the EGR control valve 21 corresponding to the target EGR rate. In the present embodiment, when the actual EGR rate deviates from the target EGR rate, EGR that can be set so that the opening area of the EGR control valve 21 corresponding to the current target EGR rate corresponds to the actual EGR rate. The correlation between the EGR rate and the opening area of the EGR control valve 21 is uniformly corrected over the entire rate range.

That is, as shown in FIG. 2, the characteristic representing the correlation between the currently set EGR rate and the opening area of the EGR control valve 21 so that the current opening area of the EGR control valve 21 corresponds to the actual EGR rate. The inclination of the line A is corrected, and thereafter the opening area of the EGR control valve 21 is set from the target EGR rate according to the relationship of the characteristic line B. In other words, an opening area correction value that is a flow rate ratio between the target EGR amount corresponding to the target EGR rate and the actual EGR amount corresponding to the actual EGR rate is calculated, and the EGR control valve 21 is based on the opening area correction value. The EGR rate set corresponding to the opening area is corrected. The opening area correction value is stored in a RAM or the like in the control unit 25 as a learning value.

When the opening area correction value is multiplied by the current opening area of the EGR control valve, a new opening area of the EGR control valve that realizes the current target EGR amount can be calculated. For example, when the actual EGR amount is 20% short of the target EGR amount, the current target EGR amount is opened by opening the opening so that the opening area of the EGR control valve is increased by 20%. Can be realized. That is, this opening area correction value is a ratio of excess or deficiency of the opening area of the EGR control valve 21 necessary for realizing the target EGR rate.

When the opening area of the EGR control valve 21 is set from the target EGR rate according to the relationship of the characteristic line B, if the actual EGR rate is deviated from the target EGR rate, the current target EGR rate is handled. The inclination of the characteristic line B is corrected so that the opening area of the EGR control valve 21 corresponds to the actual EGR rate. That is, every time the actual EGR rate deviates from the target EGR rate, the opening area correction value is calculated, and a characteristic line representing the correlation between the EGR rate and the opening area of the EGR control valve 21 is calculated based on the opening area correction value. The tilt is corrected.

As described above, even when the pressure loss of the exhaust system changes, the opening area of the corresponding EGR control valve 21 can be corrected for all the opening degrees of the EGR control valve 21, and the actual EGR amount can be reduced. It is possible to follow the target EGR amount. That is, it is possible to accurately control the amount of EGR returned to the intake passage 2.

The opening area correction value is a flow rate ratio between the target EGR amount and the actual EGR amount, and is not easily affected by the intake air temperature or the exhaust temperature. Therefore, the actual EGR amount follows the target EGR amount regardless of temperature factors. Thus, the opening area of the EGR control valve 21 can be corrected stably.

FIG. 3 is a block diagram showing the calculation content of the opening correction of the EGR control valve 21.

In S1, the provisional value of the opening area correction value is calculated by dividing the target EGR amount by the actual EGR amount. In S2, a new opening area correction value is calculated by dividing the provisional value of the opening area correction value calculated in S1 by the opening area correction value (previous value) stored as a learning value. That is, the opening area correction value is newly calculated based on the previous value of the opening area correction value. In S3, the opening area correction value newly calculated in S2 is stored as a learning value in association with the opening degree of the EGR control valve 21. In this embodiment, since the actual EGR amount is made to follow the target EGR amount by correcting the inclination of the characteristic line A representing the correlation between the EGR rate and the opening area of the EGR control valve 21, the opening area correction is performed. The value is constant regardless of the opening degree of the EGR control valve 21. In S4, the correction target EGR rate corresponding to the opening area of the EGR control valve 21 is calculated by multiplying the opening area correction value stored in S3 as the learning value and the target EGR rate. In S5, the opening area of the EGR control valve 21 corresponding to the corrected target EGR rate calculated in S4 is calculated. Then, the opening area of the EGR control valve 21 calculated in S5 is converted into the opening degree of the EGR control valve 21, and the EGR control valve 21 is controlled so as to have the converted opening degree.

When learning the aperture area correction value, as shown in FIG. 4, the aperture area correction value is updated so that the learning result up to now is more important than the provisional value of the aperture area correction value. May be. In that case, it is possible to reduce the influence when the error of the provisional value of the opening area correction value is large.

FIG. 4 is a block diagram showing the calculation content of the opening correction of the EGR control valve 21 when the opening area correction value is updated so as to place importance on the learning results up to now.

In S11, the provisional value of the opening area correction value is calculated by dividing the target EGR amount by the actual EGR amount. In S12, the first correction value is calculated by multiplying the provisional value of the opening area correction value by a predetermined coefficient K. The coefficient K is a positive value of “1” or less, and is a value such as 0.2 or 0.3, for example. In S13, the second correction value is calculated by multiplying the opening area correction value stored as the learning value by (1−K), which is a value obtained by subtracting the coefficient K from 1. In S14, the second correction value is added to the first correction value to calculate a new opening area correction value. In S15, the opening area correction value newly calculated in S14 is stored as a learning value in association with the opening of the EGR control valve 21. In this example as well, since the actual EGR amount is made to follow the target EGR amount by correcting the slope of the characteristic line A representing the correlation between the EGR rate and the opening area of the EGR control valve 21, the opening area correction is performed. The value is constant regardless of the opening degree of the EGR control valve 21. In S16, the correction target EGR rate corresponding to the opening area of the EGR control valve 21 is calculated by multiplying the opening area correction value stored as the learning value by the target EGR rate. In S17, the opening area of the EGR control valve 21 corresponding to the corrected target EGR rate calculated in S16 is calculated. Then, the opening area of the EGR control valve 21 calculated in S17 is converted into the opening degree of the EGR control valve 21, and the EGR control valve 21 is controlled so as to have the converted opening degree.

In the first embodiment described above, the current correlation between the EGR rate and the opening area of the EGR control valve 21 is uniformly corrected using the opening area correction value when the EGR control valve 21 has an arbitrary opening degree. However, an opening area correction value is calculated for each opening degree of the EGR control valve 21, and the opening area of the EGR control valve 21 corresponding to the EGR rate is corrected for each opening degree of the EGR control valve 21. Good.

A second embodiment of the present invention for correcting the opening area of the EGR control valve 21 corresponding to the EGR rate for each opening degree of the EGR control valve 21 will be described with reference to FIGS.

As described above, since a proportional relationship is established between the EGR rate and the opening area of the EGR control valve 21, in the initial state where the learning of the opening area correction value is not performed, the EGR rate and the EGR control valve 21 The characteristic line C1 indicating the correlation with the opening area passes through the origin and becomes a straight line having a predetermined inclination as shown by a broken line in FIG. That is, in the initial state, the EGR control valve 21 is controlled according to the characteristic of the characteristic line C1.

Then, when the EGR control valve 21 has an arbitrary opening degree V1, when the target EGR rate and the actual EGR rate deviate for the first time, for example, the actual EGR when the opening area A1 of the EGR control valve 21 corresponds to the opening degree V1. When the rate Ra1 is smaller than the target EGR rate Rt at that time (EGR rate corresponding to the opening area A1 in the characteristic line C1), the EGR rate at the opening area A1 of the EGR control valve 21 is set to Ra1. 5, the slope of the characteristic line C1 is changed. That is, the characteristic line indicating the correlation between the EGR rate and the opening area of the EGR control valve 21 is changed from C1 to D1. The characteristic line D1 is a straight line that passes through the origin and has a larger slope than the characteristic line C1, as indicated by a one-dot chain line in FIG.

For example, when the actual EGR rate Ra1 is 20% less than the target EGR rate Rt, the above-described opening area correction value is 1.25 (1 / 0.8 = 1.25). Then, the opening area of the EGR control valve 21 corresponding to the EGR rate is corrected so as to be uniformly 1.25 times that of the present time. For an unlearned region in which the opening area correction value corresponding to the opening degree of the EGR control valve 21 is not calculated, a temporary learning value (by interpolation using the opening area correction value when the EGR control valve 21 is the opening degree V1) Opening area correction value) is set.

If there is an unlearned region for which the opening area correction value has not been calculated in addition to the already learned region for which the opening area correction value has been calculated, the opening area of the EGR control valve 21 corresponding to the EGR rate is corrected in the unlearned region. As a result, there is a step in the value of the opening area of the EGR control valve 21 with respect to the EGR rate between the already learned region and the unlearned region.

Therefore, the opening area correction value calculated at the first time is reflected in the correction of the opening area of the EGR control valve 21 over the entire settable EGR rate so that such a step does not occur. It is.

When the EGR control valve 21 is controlled according to the characteristic of the characteristic line D1, if the actual EGR rate deviates from the target EGR rate, learning of the opening area correction value is performed. When the target EGR rate and the actual EGR rate deviate when the EGR control valve 21 is at the opening V2, for example, the actual EGR rate Ra2 at the opening area A2 of the EGR control valve 21 corresponding to the opening V2 is 5 is smaller than the target EGR rate Rt at the time (EGR rate corresponding to the opening area A2 in the characteristic line D1) so that the EGR rate at the opening area A2 of the EGR control valve 21 becomes Ra2. The slope of D1 is changed in a region where the EGR rate Ra1 or higher.

That is, the characteristic line indicating the correlation between the EGR rate and the opening area of the EGR control valve 21 is changed from D1 to E1. As shown by the solid line in FIG. 5, the characteristic line E1 is a straight line having the same characteristics as the characteristic line D1 (passing through the origin and having the same slope as the characteristic line C1) in the region where the EGR rate is 0 to Ra1. In the region where the EGR rate is greater than Ra1, the characteristic line C1 is such that when the EGR rate is Ra1, the opening area of the EGR control valve 21 is A1, and when the EGR rate is Ra2, the opening area of the EGR control valve 21 is A2. It is a straight line with a larger slope than that.

For example, when the actual EGR rate Ra2 is 10% less than the target EGR rate Rt, the opening area correction value when the EGR control valve 21 is at the opening V2 is 1.39 ( 1.25 / 0.9 = 1.39).

In the second embodiment, the opening area correction value is calculated every time the actual EGR rate deviates from the target EGR rate. The calculated opening area correction value is stored as a learning value in association with the opening degree of the EGR control valve 21 at that time.

In this second embodiment, the opening area correction value is set to 1.25 in the region where the opening degree of the EGR control valve 21 is 0 to V1. This is because when the EGR control valve 21 is at the opening degree V1, the opening area correction value is already calculated, and the correlation between the EGR rate and the opening area of the EGR control valve 21 so that the actual EGR rate follows the target EGR rate. This is because the correction is made. In the region where the opening degree of the EGR control valve 21 is V1 to V2, the opening is corrected for each opening degree of the EGR control valve 21 by interpolation between the opening area correction value at the opening degree V1 and the opening area correction value at the opening degree V2. The area correction value is determined. In the region where the opening degree of the EGR control valve 21 is V2 or more, the opening area correction value is set to 1.39.

FIG. 6 is an explanatory view schematically showing the correlation between the opening area of the EGR control valve 21 and the opening degree of the EGR control valve 21. Characteristic lines C2, D2, and E2 in FIG. 6 correspond to the above-described characteristic lines C1, D1, and E1 in FIG. When the actual EGR rate is corrected using the opening area correction value so as to follow the target EGR rate, the characteristic line indicating the correlation between the opening area of the EGR control valve 21 and the opening degree of the EGR control valve 21 changes accordingly. To do.

The calculated opening area correction value is sequentially written in a table as shown in FIG. 7 for each opening degree of the EGR control valve 21. That is, when the actual EGR rate deviates from the target EGR rate, the opening area correction value for the opening degree of the EGR control valve 21 at that time is learned.

In such a second embodiment, even when another pressure loss is added to the system, the opening area of the EGR control valve 21 determined from the target EGR rate can be accurately corrected, and the actual EGR amount Can accurately follow the target EGR amount.

In a system in which a part of the exhaust gas is recirculated as EGR from the upstream side of the compressor 11 of the turbocharger 10, the opening area of the EGR control valve 21 is constant with respect to the EGR rate. The higher the EGR rate, the greater the number of learning times, and the EGR amount is corrected more accurately. Further, the flow rate variation for each opening degree of the EGR control valve 21 can also be corrected.

Further, in correcting the correlation between the EGR rate and the opening area of the EGR control valve 21, as in the first embodiment described above, using the opening area correction value at an arbitrary opening of the EGR control valve 21, When the correlation between the EGR rate and the opening area of the EGR control valve 21 is uniformly corrected over the entire settable EGR rate, and at each opening degree of the EGR control valve 21 as in the second embodiment described above. The area correction value may be calculated, and the case where the opening area of the EGR control valve corresponding to the EGR rate is corrected for each opening degree of the EGR control valve 21 may be switched depending on the situation. For example, in a situation where the humidity is high or the outside air temperature is low, the opening area of the EGR control valve 21 is corrected in the same manner as in the first embodiment, and in other situations, the procedure is as in the second embodiment. The opening area of the EGR control valve may be corrected.

Claims

A turbocharger located upstream of the throttle valve, an EGR passage that recirculates part of the exhaust as EGR from the upstream side of the turbocharger, an EGR control valve disposed in the middle of the EGR passage, An internal combustion engine control device having an EGR amount detection means for detecting an actual EGR amount passing through the EGR control valve, wherein an opening area of the EGR control valve corresponding to an EGR rate is preset.
When the actual EGR amount deviates from the target EGR amount, it is determined that a change in pressure loss has occurred in the intake and exhaust systems of the internal combustion engine, and the EGR rate is adjusted so that the actual EGR amount matches the target EGR amount. A control apparatus for an internal combustion engine that corrects the opening area of the corresponding EGR control valve.
An opening area correction value, which is a ratio of the target EGR amount and the actual RGR amount, is calculated as a ratio of excess and deficiency of the opening area of the EGR control valve necessary for realizing the target EGR amount, and the opening area is calculated. 2. The control device for an internal combustion engine according to claim 1, wherein an opening area of the EGR control valve set corresponding to an EGR rate is corrected based on a correction value.
3. The control device for an internal combustion engine according to claim 2, wherein the correlation between the EGR rate and the opening area of the EGR control valve is uniformly corrected using the opening area correction value when the EGR control valve has an arbitrary opening degree. .
The internal combustion engine according to claim 2, wherein the opening area correction value is calculated for each opening degree of the EGR control valve, and the opening area of the EGR control valve corresponding to an EGR rate is corrected for each opening degree of the EGR control valve. Control device.
A first correction that uniformly corrects the correlation of the opening area of the EGR control valve corresponding to the EGR rate over the entire settable EGR rate using the opening area correction value when the EGR control valve has an arbitrary opening degree. Correction means;
Second correction means for calculating the opening area correction value for each opening degree of the EGR control valve and correcting the opening area of the EGR control valve corresponding to the EGR rate for each opening degree of the EGR control valve; And
The control apparatus for an internal combustion engine according to claim 2, wherein the first correction means and the second correction means can be switched and used in accordance with a situation.
When calculating the opening area correction value for each opening degree of the EGR control valve and correcting the opening area of the EGR control valve corresponding to the EGR rate for each opening degree of the EGR control valve,
The opening area correction value calculated for the first time is used as an initial learning value to reflect the correction of the opening area of the EGR control valve corresponding to the EGR ratio over the entire settable EGR ratio.
The opening area correction value calculated after the next time is used as a learning value for each opening degree of the EGR control valve to correct the opening area of the EGR control valve corresponding to the EGR rate, and the opening degree of the EGR control valve. The control apparatus for an internal combustion engine according to claim 4 or 5, wherein the control apparatus is sequentially updated every time.
When the opening area correction value is assigned and stored as a learning value for each opening of the EGR control valve, the opening area correction value is calculated in an unlearned region where the opening area correction value is not calculated. The control device for an internal combustion engine according to claim 4 or 5, wherein the temporary learning value is assigned by interpolation using the learning value of the learning region.
When the opening area correction value is assigned and stored as a learning value for each opening of the EGR control valve, the opening area correction value is calculated in an unlearned region where the opening area correction value is not calculated. The control apparatus for an internal combustion engine according to claim 4 or 5, wherein learning values in adjacent learning areas among learning areas are assigned as temporary learning values.
Detecting the actual EGR amount passing through the EGR control valve arranged in the EGR passage that recirculates a part of the exhaust as EGR from the upstream side of the turbocharger located on the upstream side of the throttle valve,
The opening area of the EGR control valve corresponding to the EGR rate is preset,
When the actual EGR amount deviates from the target EGR amount, it is determined that a change in pressure loss has occurred in the intake and exhaust systems of the internal combustion engine, and the EGR rate is adjusted so that the actual EGR amount matches the target EGR amount. A control method for an internal combustion engine that corrects the opening area of the EGR control valve corresponding to the above.