JP2007162502A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technology enabling to make variation of an intake or an exhaust condition among cylinder groups small in a control device for an internal combustion engine. <P>SOLUTION: This device is provided with a plurality of cylinder groups 2, 3, exhaust gas passages 11, 13 provided on the cylinder groups 2, 3 respectively, variable displacement turbochargers 7, 9 provided on the exhaust gas passages 11, 13 respectively and adjusting passage cross section area of exhaust gas by opening of a nozzle vale, detection means 50, 60 detecting a state value relating to an operation state of each cylinder group for each cylinder group 2, 3, a target value establishing means 15 establishing target value of the state value, and a control means 15 controlling opening of the nozzle vane of the variable displacement turbochargers 7, 9 to make difference between a detection value and a target value of the state value small for each cylinder group 2, 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine.

In the V-type engine, each bank is provided with an intake manifold and an exhaust manifold. Here, a difference occurs in the intake air amount of each bank due to manufacturing variations of the intake and exhaust systems and manufacturing variations of each bank of the internal combustion engine. As a result, it may be difficult to reduce harmful substances in the exhaust, or engine output may be reduced. In addition, when the particulate filter or NOx catalyst is provided for each bank, the time when the particulate filter needs to be regenerated, N
The time when the NOx stored in the Ox catalyst needs to be reduced or the time when the sulfur poisoning of the NOx catalyst needs to be recovered varies from bank to bank.

Here, the nozzle vanes of some of the variable capacity turbochargers provided in each bank are closed so that the exhaust does not flow to the filters of some banks, and the PM of the filter is determined from the amount of intake air detected at that time. A technique for determining the amount of collection is known (for example, see Patent Document 1).
JP 2004-339773 A Japanese Utility Model Publication No. 7-8553 JP-A-10-266866

  However, if regeneration control of another catalyst or filter is performed in accordance with one catalyst or filter, the performance of the catalyst or filter cannot be fully utilized. Furthermore, thermal degradation proceeds by raising the temperature to a filter that does not require regeneration of the filter.

  In addition, if the state of exhaust gas differs from bank to bank, the purification capacity of the catalyst may vary from bank to bank. Furthermore, the probability that the catalyst will overheat increases.

  If the regeneration of the filter, the supply control of the reducing agent, the sulfur poisoning recovery control, or the temperature control of the catalyst or the like is performed for each bank, the control logic becomes complicated. In addition, in order to reduce the manufacturing variation, it is conceivable to reduce the tolerance of parts or tighten quality control, but the manufacturing cost increases.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique capable of reducing a difference between cylinder groups in an intake or exhaust state in a control device for an internal combustion engine. And

In order to achieve the above object, a control apparatus for an internal combustion engine according to the present invention is characterized by the following. That is,
A plurality of cylinder groups;
An exhaust passage provided in each cylinder group,
A variable displacement turbocharger that is provided in each exhaust passage and adjusts the cross-sectional area of the exhaust passage according to the opening of the nozzle vane;
Detecting means for detecting, for each cylinder group, a state value related to the operating state of each cylinder group;
Target value setting means for setting a target value of the state value;
Control means for controlling the opening degree of the nozzle vanes of the variable displacement turbocharger for each cylinder group so as to reduce the difference between the target value set by the target value setting means and the detection value detected by the detection means; ,
It is provided with.

  Here, when the difference between the target value and the detected value of the state value is reduced by the control means, the state value approaches the target value for each cylinder group, so the difference in the state value between the cylinder groups is reduced. As the target value, a state value detected by the detecting means in any one of the cylinder groups may be used.

  By changing the opening of the nozzle vane provided in the variable capacity turbocharger, for example, intake air amount, intake pressure, exhaust temperature, exhaust pressure, EGR gas temperature, EGR gas pressure (hereinafter these are collectively referred to as “intake air amount, etc. ") Is changed. Here, since the variable displacement turbocharger is provided for each cylinder group, the intake air amount and the like can be changed for each cylinder group by adjusting the opening degree of the nozzle vane for each cylinder group. Then, by bringing the state value close to the target value in each cylinder group, the difference in the intake air amount or the like between the cylinder groups can be reduced.

  Examples of the “state value” include intake air amount, intake pressure, exhaust temperature, exhaust pressure, EGR gas temperature, and EGR gas pressure.

  And in this invention, the said detection means can detect the temperature of exhaust_gas | exhaustion.

  In other words, since the exhaust temperature changes by changing the nozzle vane opening of the variable displacement turbocharger, it is possible to change the exhaust temperature for each cylinder group by correcting the nozzle vane opening for each cylinder group. It becomes. Then, by making the exhaust temperature close to the target temperature in each cylinder group, the difference in exhaust temperature between the banks can be reduced.

  In the present invention, the detection means can detect the pressure of the exhaust.

  In other words, because the exhaust pressure changes by changing the nozzle vane opening of the variable capacity turbocharger, it is possible to change the exhaust pressure for each cylinder group by correcting the nozzle vane opening for each cylinder group It becomes. Then, by making the exhaust pressure close to the target pressure in each cylinder group, the difference in the exhaust pressure between the banks can be reduced.

In the present invention, an intake passage,
An EGR passage connecting the intake passage and the exhaust passage for each cylinder group;
An EGR valve provided in each EGR passage;
Further comprising
The detection means can detect the temperature of the EGR gas flowing through the EGR passage.

  In other words, the temperature of the exhaust gas changes by changing the opening degree of the nozzle vane of the variable capacity turbocharger, so that the temperature of the EGR gas also changes. Then, by correcting the opening degree of the nozzle vane for each cylinder group, the temperature of the EGR gas can be changed for each cylinder group. In each cylinder group, the temperature difference of the EGR gas between the banks can be reduced by bringing the temperature of the EGR gas close to the target temperature.

In the present invention, an intake passage;
An EGR passage connecting the intake passage and the exhaust passage for each cylinder group;
An EGR valve provided in each EGR passage;
Further comprising
The detection means can detect the pressure of EGR gas flowing through the EGR passage.

  That is, since the exhaust pressure changes by changing the opening of the nozzle vane of the variable capacity turbocharger, the EGR gas pressure also changes. Then, by correcting the opening degree of the nozzle vane for each cylinder group, it is possible to change the pressure of the EGR gas for each cylinder group. Then, by making the pressure of the EGR gas close to the target pressure in each cylinder group, the difference in the pressure of the EGR gas between the banks can be reduced.

  In the present invention, the correction value of the opening degree of the nozzle vane of the variable displacement turbocharger is obtained in a plurality of operation states of the internal combustion engine, and a relational expression between the operation state for which the correction value is obtained and the correction value is obtained. The correction value of the opening degree of the nozzle vane in other operating states can be calculated from the relational expression.

  That is, when the nozzle vane opening is corrected in each of a plurality of operating states of the internal combustion engine and the correction value at this time is stored, the same correction value can be used when the same operating state is obtained next time. Therefore, the target driving state can be obtained quickly. And if a correction value is obtained in a plurality of driving states, the relationship between the driving state and the correction value can be estimated to some extent. For example, by obtaining correction values in two different operation states, the relationship between the operation state and the correction value can be expressed as a linear function. By substituting the operating state for this linear function, it is possible to calculate a correction value.

  In the present invention, during the transient operation of the internal combustion engine, the opening degree of the nozzle vanes of the variable displacement turbocharger can be corrected based on the degree of change in the operating state of the internal combustion engine.

  Here, during the transient operation, the relationship between the engine speed and the engine load and the state value detected by the detecting means may be different from that during the steady operation. This is because during transient operation, the state value changes behind the changes in the engine speed and engine load. Further, when the degree of change in the engine speed or the engine load is different, the relationship between the engine speed and the engine load and the state value detected by the detecting means is different.

  Accordingly, during transient operation, even if a correction value for the opening degree of the nozzle vane is obtained based on the detected state value, it is not always an appropriate value. On the other hand, for example, by correcting the opening degree of the nozzle vane according to the rate of change of the engine speed and the rate of change of the engine load, appropriate correction can be performed.

  In the control apparatus for an internal combustion engine according to the present invention, since the state value related to the operating state can be changed for each cylinder group, the difference between the cylinder groups in the intake or exhaust state can be reduced.

  Hereinafter, specific embodiments of a control device for an internal combustion engine according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine according to the present embodiment.

  The internal combustion engine 1 is a V-type engine that includes a right bank 2 and a left bank 3. Each of the right bank 2 and the left bank 3 constitutes a cylinder group.

  An intake manifold 4 is connected to the right bank 2 and the left bank 3. Intake air is distributed from the intake manifold 4 to the right bank 2 and the left bank 3. A right intake pipe 5 and a left intake pipe 6 are connected to the intake manifold 4.

  In the middle of the right intake pipe 5, a compressor housing 7a of a right turbocharger 7 that operates using exhaust energy as a drive source is provided. A right air flow meter 8 that outputs a signal corresponding to the amount of air flowing through the right intake pipe 5 is provided in the middle of the right intake pipe 5 upstream of the compressor housing 7a.

  A compressor housing 9a of a left turbocharger 9 that operates using exhaust energy as a drive source is provided in the middle of the left intake pipe 6. A left air flow meter 10 that outputs a signal corresponding to the amount of air flowing through the left intake pipe 6 is provided in the middle of the left intake pipe 6 upstream of the compressor housing 9a.

  On the other hand, a right exhaust manifold 11 is connected to the right bank 2. The right exhaust manifold 11 is connected to the turbine housing 7 b of the right turbocharger 7. The turbine housing 7b is connected to the right exhaust pipe 12.

  A left exhaust manifold 13 is connected to the left bank 3. The left exhaust manifold 13 is connected to the turbine housing 9 b of the left turbocharger 9. The turbine housing 9 b is connected to the left exhaust pipe 14.

  In the internal combustion engine 1 configured as described above, the air that has passed through the right air flow meter 8 flows into the right turbocharger 7, and the air that has passed through the left air flow meter 10 flows into the left turbocharger 9. The air that has passed through the right turbocharger 7 and the left turbocharger 9 once joins in the intake manifold 4. Thereafter, the intake air is distributed from the intake manifold 4 to the right bank 2 and the left bank 3.

  The exhaust from the right bank 2 rotates the right turbocharger 7, and the exhaust from the left bank 3 rotates the left turbocharger 9.

  In the present embodiment, variable capacity turbochargers are employed for the right turbocharger 7 and the left turbocharger 9.

  The variable displacement turbocharger includes a plurality of nozzle vanes around an exhaust turbine in a turbine housing. When this nozzle vane is rotated to the closing side, the gap between adjacent nozzle vanes (that is, the passage cross-sectional area) is narrowed, and the flow path between the nozzle vanes is closed. On the other hand, when the nozzle vane is rotated to the open side, the gap between adjacent nozzle vanes (that is, the passage cross-sectional area) is widened, and the flow path between the nozzle vanes is opened.

  In the variable displacement turbocharger configured as described above, the direction, flow rate, and amount of exhaust blown to the exhaust turbine are adjusted by controlling the rotation direction and the rotation amount of the nozzle vane. As a result, the intake air amount, the supercharging pressure, the exhaust temperature, the exhaust pressure, the EGR gas temperature, and the EGR gas pressure change. The opening amount of the nozzle vane is hereinafter referred to as “VN opening”.

  The internal combustion engine 1 is also provided with a right EGR device 20 that recirculates a part of the exhaust gas from the right bank 2 (hereinafter referred to as EGR gas) to the intake manifold 4, and intakes the EGR gas from the left bank 3. A left EGR device 30 is provided for recirculation to the manifold 4.

  The right EGR device 20 includes a right EGR passage 21 and a right EGR valve 22. The right EGR passage 21 connects the right exhaust manifold 11 and the right intake pipe 5 upstream of the intake manifold 4 and downstream of the compressor housing 7 a of the right turbocharger 7.

  The left EGR device 30 includes a left EGR passage 31 and a left EGR valve 32. The left EGR passage 31 connects the left exhaust manifold 13 and the left intake pipe 6 upstream of the intake manifold 4 and downstream of the compressor housing 9 a of the left turbocharger 9.

  In the middle of the right exhaust pipe 12 downstream of the turbine housing 7b of the right turbocharger 7, a right exhaust temperature sensor 50 for outputting a signal corresponding to the temperature of the exhaust gas flowing through the right exhaust pipe 12, and the right exhaust A right exhaust pressure sensor 51 that outputs a signal corresponding to the pressure of exhaust in the pipe 12 is attached. Further, in the middle of the right EGR passage 21, a right EGR temperature sensor 52 that outputs a signal corresponding to the temperature of the EGR gas that circulates in the right EGR passage 21, and an EGR gas that circulates in the right EGR passage 21. An EGR pressure sensor 53 that outputs a signal corresponding to the pressure is attached.

  On the other hand, in the middle of the left exhaust pipe 14 downstream of the turbine housing 9b of the left turbocharger 9, a left exhaust temperature sensor 60 that outputs a signal corresponding to the temperature of the exhaust gas flowing through the left exhaust pipe 14, and the A left exhaust pressure sensor 61 that outputs a signal corresponding to the exhaust pressure in the left exhaust pipe 14 is attached. Further, in the middle of the left EGR passage 31, a left EGR temperature sensor 62 that outputs a signal corresponding to the temperature of the EGR gas flowing in the left EGR passage 31, and the EGR gas flowing in the left EGR passage 31 An EGR pressure sensor 63 that outputs a signal corresponding to the pressure is attached.

  In the present embodiment, it is sufficient that at least one type of sensor is provided in each bank. In addition, the right bank 2 and the left bank 3 are each provided with sensors having the same detection target. Hereinafter, these sensors are collectively referred to as “each sensor”.

  Further, the exhaust temperature sensor and the exhaust pressure sensor may be attached upstream of the turbocharger. Furthermore, when the EGR gas temperature sensor is provided with an EGR cooler, it may be attached either upstream or downstream of the EGR cooler.

  The internal combustion engine 1 configured as described above is provided with an ECU 15 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 15 is a unit that controls the operation state of the internal combustion engine 1 in accordance with the operation conditions of the internal combustion engine 1 and the request of the driver.

  In addition to the above sensors, the ECU 15 includes an accelerator opening sensor that outputs a signal corresponding to the accelerator opening, that is, the engine load, a crank position sensor that outputs a signal corresponding to the rotational speed of the internal combustion engine 1, and an intake of the internal combustion engine 1. An air flow meter that outputs a signal corresponding to the amount of air is connected via electric wiring, and the output signals of these sensors are input to the ECU 15.

On the other hand, the ECU 15 is connected to the right turbocharger 7, the left turbocharger 9, the right EGR valve 22, and the left EGR valve 32 through electric wiring, and the ECU 15 controls these devices.

  Here, the right turbocharger 7 and the left turbocharger 9 may have different supercharging capabilities due to variations in manufacturing. In such a case, the intake air amount, the supercharging pressure, the exhaust temperature, the exhaust pressure, the EGR gas temperature, or the EGR gas pressure of the right bank 2 and the left bank 3 are different. The right EGR valve 22 and the left EGR valve 32 also have different EGR amounts between banks due to manufacturing variations. As a result, the intake air amount, supercharging pressure, exhaust temperature, exhaust pressure, EGR gas temperature, or EGR gas pressure differ between banks.

  Therefore, in this embodiment, the VN opening is set for each bank so that the intake air amount, the supercharging pressure, the exhaust temperature, the exhaust pressure, the EGR gas temperature, or the EGR gas pressure in the right bank 2 and the left bank 3 are the same. Correct the degree. That is, if the VN opening is corrected for each bank, the intake air amount, the supercharging pressure, the exhaust temperature, the exhaust pressure, the EGR gas temperature, or the EGR gas pressure changes for each bank. It is possible to make the values of the intake air amount and the like of 3 substantially the same.

  In this embodiment, the VN opening correction and learning control are performed in each of the right bank 2 and the left bank 3. Further, correction is made so that the difference in the intake air amount between the right bank 2 and the left bank 3 is eliminated. Further, correction is made according to the response delay of each sensor during transient operation.

  Here, FIG. 2 and FIG. 3 are flowcharts showing a flow of VN opening correction control according to the present embodiment. This routine is repeatedly executed every predetermined time. This routine is executed for each cylinder group, that is, for each of the right bank 2 and the left bank 3. Further, in this routine, the VN opening degree of the right turbocharger 7 and the left turbocharger 9 can be corrected based on the value detected for any one of the detection targets in each sensor.

  In step S101, it is determined whether or not the learned value of the VN opening may be reflected. For example, when the warm-up of the internal combustion engine 1 is completed, when the right EGR valve 22 and the left EGR valve 32 are not abnormal, or when the right EGR passage 21 and the left EGR passage 31 are not clogged, the learning of the VN opening degree is performed. It is determined that the value may be reflected. A known technique can be used to determine whether or not each device has an abnormality. The learning of the VN opening will be described later.

  If an affirmative determination is made in step S101, the process proceeds to step S102, whereas if a negative determination is made, the process proceeds to step S105.

  In step S102, it is determined whether learning of the VN opening is completed. The determination method will be described later.

  If an affirmative determination is made in step S102, the process proceeds to step S103, whereas if a negative determination is made, the process proceeds to step S105.

  In step S103, a learned value of the VN opening is calculated. The learned value of the VN opening is a value used for correcting the VN opening, and is calculated based on a correction value obtained when the VN opening is corrected previously. This calculation method will be described later.

In step S104, the learned value reflecting VN opening command value is calculated by adding the learned value of the VN opening to the base opening. The base opening is a VN opening that is calculated based on the operating state of the internal combustion engine 1 (for example, the engine speed and the engine load), and is obtained and mapped in advance through experiments or the like. The VN opening command value after reflecting the learning value is a command value for the VN opening reflecting the correction result of the previous VN opening.

  In step S105, it is determined whether or not the VN opening correction may be executed. The determination is performed with the same contents as in step S101.

  If an affirmative determination is made in step S105, the process proceeds to step S106. On the other hand, if a negative determination is made, this routine is temporarily terminated.

  In step S106, it is determined whether each sensor has an abnormality.

  For example, with respect to the engine speed and the engine load, a range in which the output value of each sensor is a normal value is obtained and set in advance through experiments or the like, and the output value of each sensor is within a preset range. At some point, it is determined that there is no abnormality in each sensor. Further, when the difference between the output values of the sensors between the cylinder groups is greater than or equal to a predetermined value, it may be determined that there is an abnormality in any of the cylinder groups.

  If an affirmative determination is made in step S106, this routine is temporarily terminated. On the other hand, if a negative determination is made, the process proceeds to step S107.

  In step S107, the target value of the output value of each sensor is calculated based on the operating state of the internal combustion engine 1. The target value of the output value of each sensor indicates the target value of exhaust temperature, exhaust pressure, EGR gas temperature, or EGR gas pressure.

  For example, the relationship between the engine speed and the engine load and the target value of the output value of each sensor is obtained in advance by experiments and mapped, and the engine speed and engine load are substituted into the map to output the output of each sensor. Calculate the target value.

  In step S108, the actual output value of each sensor is read as the detection value of each sensor.

  In step S109, the difference between the target value of each sensor output value and the detected value is calculated. In this step, the difference between the target value and the detected value is calculated for each bank in order to eliminate the difference in the detected value of each sensor between the right bank 2 and the left bank 3. Then, by eliminating the difference between the target value and the detected value for each bank, the difference in the detected value of each sensor between the right bank 2 and the left bank 3 can be finally eliminated. That is, the difference in exhaust temperature, exhaust pressure, EGR gas temperature, or EGR gas pressure can be eliminated.

  In this step, the difference between one bank and the other bank may be obtained using either the right bank 2 or the left bank 3 as a reference.

  In step S110, it is determined whether the internal combustion engine 1 is in an idle state or a steady state. Here, there is a time delay (hereinafter referred to as response delay) from when the VN opening degree changes during transient operation until the effect of the change in the VN opening appears in the output value of each sensor. Therefore, during transient operation, correction according to response delay is also performed. This correction method will be described later.

  If an affirmative determination is made in step S110, the process proceeds to step S114. On the other hand, if a negative determination is made, the process proceeds to step S111.

  In step S111, it is determined whether or not the vehicle is in an accelerated state.

  If an affirmative determination is made in step S111, the process proceeds to step S112. On the other hand, if a negative determination is made, the process proceeds to step S113.

  In step S112, a correction value corresponding to the response delay of the output value of each sensor during vehicle acceleration is calculated. A method for calculating the correction value will be described later.

  In step S113, a correction value corresponding to the response delay of the output value of each sensor during vehicle deceleration is calculated. A method for calculating the correction value will be described later.

  In step S114, the VN opening correction value for the target bank is calculated based on the difference between the target value calculated in step S109 and the detected value. In this step, the correction value is calculated so that there is no difference between the target value and the detected value. The relationship between the difference between the target value and the detected value and the VN opening correction value that eliminates the difference is obtained in advance through experiments or the like and mapped. In addition, when the correction value for the response delay at the time of acceleration or deceleration is calculated in step S112 or step S113, the correction value for the response delay is added to the correction value of the VN opening obtained from the map. Is newly set as a VN opening correction value.

  In step S115, the final VN opening command value is calculated by adding the VN opening correction value calculated in step S114 to the VN opening command value after reflecting the learning value calculated in step S104. The VN opening is controlled based on the final VN opening command value.

  Until the learned value of the VN opening is calculated, 0 is substituted for the VN opening command value after reflecting the learned value.

  Thus, the VN opening is corrected for each bank, and the difference between the target value and the detected value of the output value of each sensor is reduced for each bank. The difference in pressure, EGR gas temperature, or EGR gas pressure can be reduced. As a result, the difference in intake air amount or supercharging pressure between the right bank 2 and the left bank 3 can be reduced.

  Next, the calculation method of the learning value of the VN opening degree in step S103 will be described.

  In this embodiment, the VN opening is corrected during idling and in any steady running, and the correction value of the VN opening in other operating states is estimated from this correction value.

  Here, FIG. 4 is a diagram showing the relationship between the intake air amount and the correction value of the VN opening when two-point correction is performed. In FIG. 4, correction values for the VN opening are obtained in two operating states with different intake air amounts, and correction values for the VN opening for other intake air amounts are obtained by estimation. Here, the VN opening correction values at the two points must be changed in order to eliminate the difference between the target intake air amount and the detected intake air amount in the current operating state. As required.

  In FIG. 4, Xi represents the intake air amount during idling, and Xa represents the intake air amount during any steady operation. Further, the correction value Yi of the VN opening at the time of idling and the correction value Ya of the VN opening at an arbitrary steady operation are obtained. Thus, when the correction value of the VN opening is obtained in two operating states with different intake air amounts, it is determined in step S102 that the learning of the VN opening is completed.

  Then, in FIG. 4, the following equation is obtained as a straight line connecting the point at the time of idling and the point at the time of arbitrary steady operation.

Y = {(Ya-Yi). (X-Xi) / (Xa-Xi)} + Yi
By substituting the detected intake air amount X into this equation, the correction value Y of the VN opening at that time can be obtained.

  Further, a command value for the VN opening may be used instead of the intake air amount.

  FIG. 5 is a diagram showing the relationship between the VN opening command value and the VN opening correction value when two-point correction is performed. In FIG. 5, correction values for VN opening are obtained in two operating states with different VN opening command values, and VN opening correction values for other VN opening command values are obtained by estimation. . Here, the VN opening correction values at the two points must be changed in order to eliminate the difference between the target VN opening and the detected VN opening in the operation state at that time. As required.

  In FIG. 5, Xi represents the VN opening command value during idling, and Xa represents the VN opening command value during any steady operation. Further, the correction value Yi of the VN opening at the time of idling and the correction value Ya of the VN opening at an arbitrary steady operation are obtained. Then, in FIG. 5, the same equation as in FIG. 4 is obtained as a straight line connecting the point at the time of idling and the point at the time of arbitrary steady operation. By substituting the command value of the VN opening into this equation, the correction value of the VN opening at that time can be obtained.

  When the two-point correction shown in FIGS. 4 and 5 is performed, there is almost no difference between each target value and the detected value, so that it is not necessary to perform the two-point correction immediately after that. Therefore, when the correction value Yi of the VN opening during idle operation and the correction value Ya of the VN opening during any steady operation become equal to or greater than a predetermined value, FIG. 4 or FIG. 5 may be updated.

  Furthermore, the calculation accuracy of the correction value of the VN opening can be improved by obtaining the correction value of the VN opening at more than two points.

  FIG. 6 is a diagram showing the relationship between the intake air amount and the VN opening correction value when three-point correction is performed. Xi represents the intake air amount during idling, and Xa and Xc represent the intake air amount during any steady operation. Here, it is assumed that Xc is larger than Xa. Further, the correction value Yi of the VN opening during idling and the correction values Ya and Yc of the VN opening during any steady operation are obtained in the same manner as in the case of two-point correction. Then, in FIG. 6, a straight line connecting the point in Xi and the point in Xa and a straight line connecting the point in Xa and the point in Xc are obtained. By selecting an equation according to the detected intake air amount and substituting the detected intake air amount into this equation, a correction value for the VN opening at that time can be obtained.

  That is, when the intake air amount is between Xi and Xa, the correction value Y of the VN opening is obtained by the following equation.

Y = {(Ya-Yi). (X-Xi) / (Xa-Xi)} + Yi
When the intake air amount is between Xa and Xc, the correction value Y of the VN opening is obtained by the following equation.

Y = {(Yc-Ya). (X-Xa) / (Xc-Xa)} + Ya
A quadratic function passing through the three points or other functions may be set. An approximate expression may be set.

Similarly, FIG. 7 is a diagram showing the relationship between the VN opening command value and the VN opening correction value when three-point correction is performed. Xi represents the VN opening command value at idling, and Xa and Xc represent the VN opening command value at any steady operation. Here, it is assumed that Xc is smaller than Xa. Further, the correction value Yi of the VN opening during idling and the correction values Ya and Yc of the VN opening during any steady operation are obtained in the same manner as in the case of two-point correction. Then, in FIG. 7, a straight line connecting the point in Xi and the point in Xa and a straight line connecting the point in Xa and the point in Xc are obtained. By selecting an equation according to the detected VN opening command value and substituting the VN opening command value into this equation, a correction value for the VN opening at that time can be obtained.

  When the three-point correction shown in FIGS. 6 and 7 is performed, there is almost no difference between each target value and the detected value, so that it is not necessary to perform the three-point correction immediately after that. Therefore, when the correction value Yi of the VN opening during idle operation and the correction values Ya and Yc of the VN opening during any steady operation become equal to or greater than a predetermined value, FIG. 6 or FIG. 7 may be updated. Good.

  Further, four or more correction values may be obtained. After the correction value for the VN opening at the two points can be obtained, the correction value for the other operating state is calculated based on the two points to obtain the third correction value for the VN opening. At this point, correction values for other operating states may be calculated based on the three points. And the point which acquired the correction value of VN opening may be increased sequentially.

  Next, the process in step S112 and step S113 will be described.

  In step S112 in this embodiment, the response delay of the exhaust temperature, exhaust pressure, EGR gas temperature, or EGR gas pressure generated during acceleration is corrected. Further, in step S113, the response delay of the exhaust temperature, the exhaust pressure, the EGR gas temperature, or the EGR gas pressure generated during deceleration is corrected. Here, at the time of acceleration or deceleration, the exhaust temperature, the exhaust pressure, the EGR gas temperature, or the EGR gas pressure does not become the same value as in the steady state even at the same engine speed and engine load as in the steady state. That is, even if the engine speed and the engine load change, the exhaust temperature, the exhaust pressure, the EGR gas temperature, or the EGR gas pressure does not change immediately, but gradually changes while eventually changing the engine speed and the engine. The value depends on the load. Therefore, even if the exhaust temperature, exhaust pressure, EGR gas temperature, or EGR gas pressure is detected by each sensor during acceleration or deceleration, the values do not correspond to the engine speed and the engine load. Even if learning or correction of the VN opening is performed based on this, it is difficult to obtain an appropriate VN opening.

  Therefore, in this embodiment, the correction value is calculated according to the degree of acceleration or deceleration in steps S112 and S113.

  For example, the relationship between the change amount of the engine speed and the change amount of the fuel injection amount (may be the change amount of the engine load or the change amount of the accelerator opening) and the correction value of the VN opening degree is obtained in advance by experiments or the like. Map it. The VN opening correction value thus obtained is added to the VN opening correction value calculated in step S114.

  Further, for example, the relationship between the change amount of the intake air amount and the change amount of the fuel injection amount (may be the change amount of the engine load or the change amount of the accelerator opening) and the correction value of the VN opening degree is experimentally determined in advance. It may be obtained and mapped to obtain a correction value for the VN opening. In addition, these change amounts are good also as a change rate.

  As described above, according to the present embodiment, it is possible to eliminate the difference between the banks of the intake air amount, the supercharging pressure, the exhaust temperature, the exhaust pressure, the EGR gas temperature, or the EGR gas pressure.

Here, when the intake manifold 4 is shared by the right bank 2 and the left bank 3 as in this embodiment, more air is sucked into the bank with the smaller exhaust pressure. Further, in the case where an intake manifold is provided for each cylinder group, if the exhaust pressure differs between banks, the higher the exhaust pressure, the greater the recirculation amount of EGR gas. Then, the intake air amount of the bank having the larger EGR gas recirculation amount becomes smaller.

On the other hand, in this embodiment, since the EGR gas is uniformly introduced into the right bank 2 and the left bank 3, the exhaust state (for example, NOx amount, HC amount, CO amount, or PM amount) is changed. It becomes possible to make it substantially the same. Further, if the EGR amount is the same between the right bank 2 and the left bank 3, the temperature of the intake manifold 4 becomes substantially uniform, so that the difference between the banks of the EGR amount and the intake air amount can be reduced.

  Further, even if the EGR gas is not recirculated, the rotation difference between the right turbocharger 7 and the left turbocharger 9 can be suppressed, so that the over rotation of one turbocharger can be suppressed. And the output difference between banks can also be reduced.

  When the NOx catalyst is provided for each bank, NOx reduction can be performed stably. Furthermore, it becomes easy to control the temperature of the NOx catalyst at the time of sulfur poisoning recovery, and overheating of the NOx catalyst can be suppressed. In addition, even when a particulate filter is provided for each bank, temperature control during filter regeneration is facilitated, and overheating of the filter can be suppressed. Furthermore, abnormality detection when an abnormality occurs in the internal combustion engine 1 is facilitated.

It is the figure which showed schematic structure of the internal combustion engine by the Example. It is the flowchart which showed the flow of VN opening correction control by an Example. It is the flowchart which showed the flow of VN opening correction control by an Example. It is the figure which showed the relationship between the intake air amount when performing 2 point | piece correction, and the correction value of VN opening degree. It is the figure which showed the relationship between the command value of VN opening when two-point correction | amendment was performed, and the correction value of VN opening. It is the figure which showed the relationship between the intake air amount when performing 3 point | piece correction, and the correction value of VN opening degree. It is the figure which showed the relationship between the command value of VN opening when three-point correction is performed, and the correction value of VN opening.

Explanation of symbols

1 Internal combustion engine 2 Right bank 3 Left bank 4 Intake manifold 5 Right intake pipe 6 Left intake pipe 7 Right turbocharger 7a Compressor housing 7b Turbine housing 8 Right air flow meter 9 Left turbocharger 9a Compressor housing 9b Turbine housing 10 Left air flow meter 11 Right Exhaust manifold 12 Right exhaust pipe 13 Left exhaust manifold 14 Left exhaust pipe 15 ECU
20 Right EGR device 21 Right EGR passage 22 Right EGR valve 30 Left EGR device 31 Left EGR passage 32 Left EGR valve 50 Right exhaust temperature sensor 51 Right exhaust pressure sensor 52 Right EGR temperature sensor 53 Right EGR pressure sensor 60 Left exhaust temperature sensor 61 Left exhaust pressure sensor 62 Left EGR temperature sensor 63 Left EGR pressure sensor

Claims (7)

A plurality of cylinder groups;
An exhaust passage provided in each cylinder group,
A variable displacement turbocharger that is provided in each exhaust passage and adjusts the cross-sectional area of the exhaust passage according to the opening of the nozzle vane;
Detecting means for detecting, for each cylinder group, a state value related to the operating state of each cylinder group;
Target value setting means for setting a target value of the state value;
Control means for controlling the opening degree of the nozzle vanes of the variable displacement turbocharger for each cylinder group so as to reduce the difference between the target value set by the target value setting means and the detection value detected by the detection means; ,
A control apparatus for an internal combustion engine, comprising:   2. The control apparatus for an internal combustion engine according to claim 1, wherein the detection means detects the temperature of the exhaust gas.   2. The control device for an internal combustion engine according to claim 1, wherein the detection means detects the pressure of the exhaust gas. An intake passage,
An EGR passage connecting the intake passage and the exhaust passage for each cylinder group;
An EGR valve provided in each EGR passage;
Further comprising
2. The control device for an internal combustion engine according to claim 1, wherein the detection means detects a temperature of EGR gas flowing through the EGR passage. An intake passage,
An EGR passage connecting the intake passage and the exhaust passage for each cylinder group;
An EGR valve provided in each EGR passage;
Further comprising
2. The control device for an internal combustion engine according to claim 1, wherein the detection unit detects a pressure of EGR gas flowing through the EGR passage. 3.   In a plurality of operating states of the internal combustion engine, the correction value of the opening of the nozzle vane of the variable displacement turbocharger is obtained, and a relational expression between the operation state in which the correction value is obtained and the correction value is obtained, and other operating states 6. The control device for an internal combustion engine according to claim 1, wherein a correction value of the opening degree of the nozzle vane is calculated from the relational expression.   7. The nozzle vane opening degree of the variable displacement turbocharger is corrected based on the degree of change in the operating state of the internal combustion engine during the transient operation of the internal combustion engine. The internal combustion engine control device described.

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