JPH0562218B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a boost pressure control device for a turbocharger in a turbocharged engine.

[Conventional technology]

A turbocharger uses the high-temperature, high-pressure energy of engine exhaust gas to rotate an exhaust turbine at high speed and drive a compressor on the same axis.As the rotation speed of the compressor increases, the intake manifold increases. Intake pressure can be increased above atmospheric pressure.

In this way, by supercharging a large amount of air into the engine, high torque and high power are generated.
It also aims to improve fuel efficiency.

However, in the case of automobile engines that have a wide operating speed range, due to the characteristics of the turbocharger, it is possible to secure sufficient boost pressure in the medium-to-high speed range, but it is difficult to obtain sufficient exhaust pressure in the low-speed range. Therefore, the rotational speed of the exhaust turbine does not increase, the boost pressure decreases, and the low-speed torque of the engine tends to be insufficient.

The driving efficiency of an exhaust turbine is determined according to the ratio A/R of the cross-sectional area A of the turbine scroll part, which is the introduction part of the exhaust gas into the turbine, and the radius R from its center. Even in a low-speed operating range, if this A can be reduced to increase the exhaust flow velocity, the turbine rotational speed can be increased and the supercharging pressure can be increased.

Therefore, a turbocharger equipped with a variable capacity means for varying the A/R of the exhaust turbine has been filed by the present applicant as Japanese Patent Application No. 162918/1982. However, sufficient boost pressure can be obtained.

The variable capacity means installed in the exhaust gas introduction part of the exhaust turbine to increase and decrease the opening degree is driven by an actuator whose operating pressure is the supercharging pressure generated downstream of the compressor, and a solenoid valve is used to adjust this operating pressure. The solenoid valve adjusts the pressure by releasing a portion of the operating pressure to the atmosphere.For example, the operation may be controlled by a control device such as a microcomputer depending on the operating state of the engine. It's getting old.

In addition, this solenoid valve is an on-off type solenoid valve that opens and closes at a predetermined frequency, and the valve opening time ratio is controlled according to its control duty. For example, when the duty representing the opening time is 100%, the solenoid valve is closed. In this case, the variable capacity means controls A to the minimum through the actuator, and the turbine rotational speed is immediately increased. Conversely, when the duty is 0%, the solenoid valve is fully closed and A is minimized. becomes maximum, suppressing the turbine rotation speed.

In actual control, in order to further improve control accuracy, the target boost pressure set according to the operating state is compared with the actual boost pressure detected by the boost pressure sensor, and the By correcting the control duty, the boost pressure is feedback-controlled to match the target boost pressure.

On the other hand, although such a capacity variable means secures supercharging pressure in low-speed operating ranges where the exhaust gas flow rate is small, in high-speed, high-load operating ranges where the exhaust gas flow rate increases, even if the cross-sectional area A is maximized, the In this case, the speed of flow introduced into the turbine does not decrease, and the rotational speed increases rapidly, causing the boost pressure to exceed the allowable upper limit.

Therefore, when the boost pressure approaches the upper limit value, an exhaust bypass valve is provided that bypasses a portion of the exhaust gas from upstream to downstream of the exhaust turbine to suppress the boost pressure. When the exhaust bypass valve opens, the amount of exhaust gas flowing into the exhaust turbine is reduced, thereby reducing the turbine rotational speed and preventing the supercharging pressure from exceeding the upper limit.

Regarding the control of this exhaust bypass valve, the supercharging pressure is detected and feedback control is performed in the same manner as the capacity variable means to improve the control accuracy of the supercharging pressure.

Note that when the variable capacity means and the exhaust bypass valve are both subjected to feedback control in this way, there is a region where the controls interfere with each other, so that the variable capacity means and the exhaust bypass valve are not originally used to control the boost pressure. It is also expected that the position will deviate from the optimum position.

For example, when the boost pressure approaches the upper limit in a high-speed operating range, the capacity variable means would normally open fully and not throttle the exhaust, but if the exhaust bypass valve adjusts its opening according to the boost pressure, the exhaust would be reduced. It is possible to optimally control the boost pressure while maintaining good engine output efficiency without increasing the pressure, but in this case, if the capacity variable means narrows the opening and increases the exhaust flow velocity, the exhaust bypass valve will increase accordingly. Even if it is opened extra, the boost pressure can be controlled at the same level.

However, in this case, the variable capacity means unnecessarily narrows the exhaust flow path, which increases the exhaust pressure and reduces the exhaust efficiency of the engine, resulting in a decrease in output efficiency.

Therefore, when performing feedback control using these capacity variable means and the exhaust bypass valve, it is necessary to set the area in which feedback control is to be performed depending on the operating state of the engine (feedback control includes proportional control, integral control, etc.). There is, but
It is not necessarily necessary to set separate control regions for all of these; for example, such a control region may be set only for integral control), and when one is performing feedback control, the other is fixed. By doing so, problems caused by control interference can be avoided.

[Problem that the invention seeks to solve]

By the way, when performing supercharging pressure control using such a capacity variable means and an exhaust bypass valve, integral control is required during feedback control in order to accurately control the supercharging pressure to a target value without steady-state deviation. This integral control needs to be started when the target supercharging pressure is approached, considering the response delay of the actuator.

If the point at which this integral control starts is not selected optimally, the boost pressure may not reach the target value or may significantly exceed the target value, resulting in poor acceleration performance and damage to the engine. The problem of giving arises.

The present invention was made to solve these problems, and the starting point of integral control during feedback control by the variable displacement means and the exhaust bypass valve is set according to the target boost pressure determined by the operating state of the engine. The objective is to optimally select the boost pressure of the turbocharger in all operating ranges.

[Means for solving problems]

Therefore, the boost pressure control device for a booster charger according to the present invention is constructed as shown in the functional block diagram of FIG.

That is, the supercharging pressure of the turbocharged engine 1 is controlled by the capacity variable means 11 that varies the A/R of the exhaust turbine of the turbocharger, and the exhaust bypass valve 12 that bypasses a part of the exhaust gas passing through the exhaust turbine from upstream to downstream. Controlled according to operating conditions.

Reference numeral 2 denotes an operating state detection means for detecting parameters representative of the operating state of the engine 8, such as the amount of intake air or engine rotation speed, and 3 indicates a target for setting a target boost pressure according to the detected operating state. A supercharging pressure setting means 4, a supercharging pressure detecting means for detecting the actual supercharging pressure supercharged by the turbocharger of the engine 1, and a supercharging pressure detecting means 5 for detecting the supercharging pressure detected by the supercharging pressure and the target supercharging pressure setting means 3. This is a deviation calculation means for calculating the deviation from the target supercharging pressure that has been set.

Reference numeral 6 denotes a feedback control region determining means, which determines the operating region in which feedback control is to be performed based on the engine operating state detected by the operating state detecting means 2 and the supercharging pressure detected by the supercharging pressure detecting means 4; Which of the variable capacity means 11 and the exhaust bypass valve 12 is to be subjected to feedback control is selected.

Reference numeral 7 denotes first control amount calculation means for calculating the control amount of the exhaust turbine capacity variable means 11 in accordance with parameters representing the operating state including at least the integrated value of the deviation calculated by the deviation calculation means; 8 is the same; It is a second control amount calculation means that calculates a control amount of the exhaust bypass valve according to a parameter representing an operating state including at least the integrated value of the above-mentioned deviation.

Reference numeral 9 denotes a first control means for driving and controlling the capacity variable means 11 according to the control amount calculated by the control amount calculation means 7; 10 an exhaust bypass valve 12 according to the control amount calculated by the control amount calculation means 8; This is second control means for driving and controlling the.

The boost pressure control device for a turbocharger according to the present invention further includes a determining means for determining a region in which integral control during feedback control is started according to the target boost pressure. The amount calculation means 7 and the second controlled amount calculation means 8,
It also has the function of this discrimination means.

However, this determining means may be provided separately from the first and second control amount calculating means.

[Effect]

The feedback control area determining means 8 provides feedback control areas for the variable capacity means 11 and the exhaust bypass valve 12, respectively, and these are basically controlled independently in each area.

In both systems, the first and second control amount calculation means 7 and 8 that calculate the control amount calculate the deviation between the target boost pressure calculated by the deviation calculation means 5 and the actual boost pressure. Based on this input, for example, the range in which integral control is started according to the target boost pressure is determined so that integral control is performed only when this deviation falls within a predetermined value, and the operating state is determined. To enable smooth entry into integral control in response to target boost pressure that changes in accordance with.

This prevents the boost pressure from reaching the target value or from overshooting.

〔Example〕

Examples of the present invention will be described below.

FIG. 2A is a flowchart extracted from a flowchart showing the overall control of the capacity variable means and exhaust bypass valve, which will be described later as an embodiment of the invention, and mainly focuses on the P2FBCONT shown in FIG. This process corresponds to steps 115 to 118 in the process, and will be explained first.

The process shown in this flowchart has a control period (50ms)
It is executed once every time, and is performed by a control device such as a microcomputer that controls the capacity variable means and the actuator for driving the exhaust bypass valve.

First, in step 500, a target boost pressure is calculated based on a table as shown in FIG. 2B in accordance with the intake air flow rate indicating the engine operating condition.

Next, in step 501, the deviation SA between this target boost pressure and the measured actual boost pressure is determined.

Then, in step 502, a variable capacity means (hereinafter abbreviated as "VN") and an exhaust bypass valve (weight gate valve, hereinafter abbreviated as "WG") are installed.
Each basic control amount is determined from a table as shown in FIG. 2C.

Next, in step 503, the deviation SA obtained in step 501 is compared with a predetermined value set in advance, and if it is larger than that, the process proceeds to step 506, and the deviation SA obtained in step 501 is compared with a predetermined value. The control amount) is determined for each of VN and WG. deviation
If SA is less than the predetermined value, the process proceeds to step 504 and calculates the control amount including integral control.
Find the control amount for each of VN and WG. Thereafter, in step 505, each control amount is output.

In this case, the determination in step 503 corresponds to means for determining a region in which integral control during feedback control is to be started in accordance with the target boost pressure. In this example, the determination is based on the deviation SA, but this is equivalent to using the target boost pressure.

FIG. 18 is a diagram showing a comparative example between a conventional case in which the integral control region is fixed and a case in which the integral control region is changed according to the target boost pressure according to the present invention.

Conventionally, for example, the Pa point was always used as the starting point for integral control, so if the air flow rate increases after acceleration starts and the target boost pressure decreases, gradual fluctuations in boost pressure will cross the Pa point. Then, the integral control is reset, and the supercharging pressure fluctuates as shown by the broken line a.

To avoid this, if the starting point of integral control is lowered as shown by Pa' in Fig. 19, if the target boost pressure is high, integral control will start from a point that deviates significantly from the target boost pressure. The integral term becomes too large, resulting in large boost pressure and overshoot.

In this invention, as shown by the broken line c in Fig. 18, the integral control starting point is changed according to the target boost pressure (to the point where the deviation becomes a constant value Psa), so that the actual boost pressure is For example, it changes as shown by the solid line b.

Therefore, large overshoot and control hunting, which have been problems in the past, do not occur.

In addition, in each curve showing the VN opening degree, VN control duty, and VN control duty integral term in Fig. 18,
The solid line shows the case of control according to the present invention, and the broken line shows the case of conventional control.

Above, we have explained an example in which the boost pressure is controlled on the capacity variable means VN side, but the exhaust bypass valve
When controlling the boost pressure on the WG side, similar results can be obtained by similarly changing the starting point of integral control according to the target boost pressure.

Next, specific embodiments of the present invention will be described in detail.

FIG. 3 is a schematic diagram showing the mechanical configuration of an embodiment of the present invention, in which air is supplied to the engine 21 via an intake pipe 22 and an intake manifold 23, and an exhaust manifold 24 and an exhaust pipe 2.
It is exhausted through 5.

An air flow meter 31 for measuring the amount of intake air Qa is provided at the end of the intake pipe 22 that is bent to the left in the figure, and a compressor 35 that forms part of the turbocharger is provided at the bend of the intake pipe 22. is provided to pressurize intake air supplied via the air flow meter 31 and supply it to the engine 21.

A throttle valve 32 is disposed at the base end of the intake pipe 22 close to the intake manifold 23.
A relief valve 29 is provided in the intake pipe 22 between the compressor 2 and the compressor 35.

A portion of the exhaust pipe 25 bent to the right in the figure forms a turbine chamber 38, and a turbine 37 is disposed within this turbine chamber 38, and the turbine 37 is connected to the compressor 35 via a connecting shaft 36. There is.

The turbine chamber 38 includes a scroll 3 formed to surround the turbine 37 as shown in FIG.
9, and this scroll 39 has a cross-sectional area that gradually decreases as it goes downstream in the direction indicated by arrow F from the exhaust gas introduction passage 40.

A movable tongue portion 45 as a capacity variable means constituted by a flap valve is provided at the confluence of the exhaust gas introduction passage 40 to the scroll 39 and the terminal end portion 41 of the scroll 39. The base end portion of the passage 40 is rotatably supported by a shaft 46 so that the cross-sectional area of the passage 40 can be expanded or contracted.

This movable tongue portion 45 is disposed within the exhaust pipe 25 near the upstream side, which is the exhaust gas introduction passage 40 to the turbine 37 in FIG. A shaft 46 rotatably supporting the movable tongue portion 45 is connected to the upper end of a rod 48 via an arm 47, and the lower end of the rod 48 is connected to a diaphragm 52 constituting an actuator 50 for driving the movable tongue portion. connected.

Case 51 housing diaphragm 52
is divided into an atmospheric chamber 53 and a positive pressure chamber 54 by a diaphragm 52, and the atmospheric chamber 52 has a diaphragm 5.
A spring 55 is disposed to urge the pressure sensor 2 toward the positive pressure chamber 54 side.

The positive pressure chamber 54 is connected to the intake pipe 22 on the downstream side of the compressor 35 via a connecting pipe 56, and the supercharging pressure generated by the compressor 35 is supplied to the positive pressure chamber 54, causing the diaphragm 52 to be connected to the spring 55. It is being pushed toward the atmospheric chamber 53 side.

Further, a solenoid valve 57 is provided in the middle of the connecting pipe 56, and when this solenoid valve 57 is driven and released by the control unit 80, the connecting pipe 56 is connected to the inlet of the compressor 35 via this solenoid valve 57. The pressure inside the positive pressure chamber 54 decreases.

More specifically, the solenoid valve 57 is duty-controlled by the control unit 80, and as the duty value increases, the degree of opening of the solenoid valve 57 increases and the pressure in the positive pressure chamber 54 decreases.

Therefore, the diaphragm 52 moves downward under the action of the spring 55 of the atmospheric chamber 53, and this movement is transmitted to the movable tongue portion 45 via the rod 48, arm 47, and shaft 46, and the movable tongue portion 45 A direction in which the exhaust gas introduction passage 40 to 37 is made smaller;
In other words, it rotates in the closing direction.

As a result, the flow rate supplied to the turbine 37 increases, and the supercharging pressure to the engine 21 by the compressor 35 increases.

Conversely, as the duty value decreases, the degree of opening of the solenoid valve 57 decreases, and the pressure in the positive pressure chamber 54 increases.
5, thereby moving the movable tongue 4 upwardly.
5 rotates in the direction to open the exhaust gas introduction passage 40.

As a result, the flow rate supplied to the turbine 37 becomes slower, and the boost pressure applied to the engine 21 by the compressor 35 decreases.

An exhaust bypass valve (wastegate valve) 60 is provided at a connection portion between the exhaust bypass passage 26 that bypasses the turbine 37 and the exhaust manifold 24 . This exhaust bypass valve 60 is connected to one end of a rod 63 via an arm 61 and a connecting member 62, and the other end of the rod 63 is connected to a diaphragm 72 of an actuator 70 for driving the exhaust bypass valve.

Case 7 that houses this diaphragm 72
1 is divided by a diaphragm 72 into an atmospheric chamber 73 and a positive pressure chamber 74, and the atmospheric chamber 73 is provided with a spring 75 that urges the diaphragm 72 toward the positive pressure chamber 74. The positive pressure chamber 74 is connected to the connecting pipe 7
The intake pipe 2 downstream of the compressor 35 via 6
2, and the supercharging pressure generated by the compressor 35 is supplied to the positive pressure chamber 74.

Further, a solenoid valve 77 is provided in the middle of the connecting pipe 76, and this solenoid valve 77 is connected to the control unit 8.
0, the connecting pipe 76 is connected to the inlet of the compressor 35 via the electromagnetic valve 77, and the pressure in the positive pressure chamber 74 is reduced.

More specifically, the solenoid valve 77 is duty-controlled by the control unit 80, and as the duty value increases, the degree of opening of the solenoid valve 77 increases, and the pressure in the positive pressure chamber 74 decreases. The diaphragm 72 moves downward under the action of the spring 75, and this movement is transmitted to the exhaust bypass valve 60 via the rod 63, the connecting member 62, and the arm 61, and the exhaust bypass valve 60 moves in the direction of closing the bypass passage 26. .

Also, the smaller the duty value, the more the solenoid valve 7
7 becomes smaller and the pressure in the positive pressure chamber 74 increases, the diaphragm 72 moves upward against the spring 75, and then the exhaust bypass valve 6
0 moves in the opening direction.

The exhaust bypass valve 60 is provided in order to prevent damage to the engine 21 due to excessively high supercharging pressure of intake air supplied to the engine 21 by the turbocharger when the engine 21 is in a high-speed, high-load state. , part of the exhaust gas from the engine 21 is discharged to the outside to reduce the amount of exhaust gas supplied to the turbine 37 so that an appropriate boost pressure can be introduced into the engine 21.

The control unit 80 is composed of a microcomputer consisting of a microprocessor, a memory, an A/D converter, an input/output interface, etc., and the intake air amount signal is sent from the air flow meter 31 to the control unit 80 via the interface. As well as being supplied, engine 2
Crank angle sensor 30 installed on the left side in figure 1
A signal corresponding to the rotation speed of the engine 21 is inputted from the engine 21, and a detection signal of the boost pressure from the boost pressure sensor 33 is inputted.

The control unit 80 appropriately controls the duty value of the signal that drives the solenoid valves 57 and 77 according to this information, and makes the cross-sectional area of the exhaust gas introduction passage 40 to the turbine 37 variable through the movable tongue portion 45. By doing so, and by varying the amount of exhaust gas to the turbine 37 via the exhaust bypass valve 60, the supercharging pressure of the intake air supplied to the engine 21 is appropriately controlled according to the intake air amount Qa, and low speed Increases torque from the operating range to the high-speed operating range.

Next, FIGS. 5A to 9 show flowcharts in which control of the variable capacity means (movable tongue portion 45) and waste gate valve (exhaust bypass valve 60) is realized using a microcomputer. The numbers in the figure indicate processing steps, and the capacity variable means are
VN and wastegate valves are described by the symbol WG, and signals indicating operating conditions such as engine speed and intake air flow rate are stored in memory.

To explain from Fig. 5A, boost pressure control
VNWGCONTROL calculation processing is performed every predetermined cycle (control cycle), and the control target value (target boost pressure) of boost pressure obtained from various operating conditions P2ADAPT
The control amount for controlling VN and WG is calculated so that the actual boost pressure P matches the actual supercharging pressure P.

To explain step by step, first, in step 200, the air flow index is calculated from the input intake air amount QA.
Ask for QS. Note that in actual control, this QS is used as calculation data, but in the following explanation, for convenience, QS will be explained as the intake air amount.

In step 201, the basic control duty of the WG is determined as BASEDUTY1 from the value of QS.

In step 202, 35 percent of the control duty is added to BASEDUTY1. This is due to missetting on the working group side, variations in parts, etc.
This is the amount of correction to prevent the WG from opening.

For example, in the control area on the VN side, WG side
If it opens, the VN will try to increase the boost pressure and shift to the closed side, making it no longer possible to perform normal learning on the VN side. Therefore, the control amount on the WG side is increased in advance to ensure the reliability of learning control on the NV side.

In step 203, a learning amount LEARNWG determined by learning control is added to BASEDUTY1 in order to eliminate steady-state deviation from the control target value.

In step 204, it is checked whether overboost control is being performed, which temporarily increases the boost pressure in response to sudden acceleration to improve acceleration performance, and if it is determined that overboost control is being performed, the process proceeds to step 205. Add acceleration correction amount for overboost control to BASEDUTY1.
Here, LEARNWG and acceleration correction amount give the feed forward control amount on the WG side. In addition,
The calculation of LEARNWG and overboost control will be described later.

On the other hand, in steps 206 to 210, the feedforward control amount on the VN side is determined from BASEDUTY0. The only difference between steps 201-205 and steps 206-210 is that the basic control duty determined for BASEDUTY 0 is subtracted by 5% in step 207.

This occurs when the basic control duty table of the VN is shifted toward the VN closing side due to a setting error on the VN side or variations in parts.
This is the amount of correction to prevent the WG from opening.

In step 208, the amount of learning is determined in the same way as on the WG side.
Add LEARNVN. Furthermore, this
The calculation of LEARNVN will also be described later.

Here, the basic control duty of VN and WG is
For example, since the basic control duty is given as the characteristics shown in FIGS. 10A and 10B, the table shown in FIG. Just ask. However, Figure 10C is
For VN, H represents hexadecimal representation.

In step 211, a feedback correction amount for the difference between the actual boost pressure P and the target boost pressure P2ADAPT is calculated, and is further added to the feedback control amount obtained earlier to obtain the final control signal amount. Find BASEDUTY0 and BASEDUTY1 respectively. Note that the feedback control P2FBCONT performed in step 211 will be described later.

In step 212, overshoot prevention at the initial stage of rapid acceleration and fail-safe processing in the event of component failure are performed.

To explain from the process of preventing overshoot, the supercharging pressure rises rapidly during sudden acceleration, but in the case of a turbocharger with VN, the rise in supercharging pressure is faster than that of a normal turbocharger, so the 16th As shown in the figure, overshoot occurs.

In particular, in the example shown in Fig. 16, the supercharging pressure is 500 mmHg during overboost control.
This may result in the engine's durability being impaired.

To prevent this, the control duty (control signal) on the WG side is temporarily reduced at the beginning of rapid acceleration, and the amount of exhaust gas that bypasses the turbine 37 in Figure 3 is increased to reduce the boost pressure. Let it happen.

More specifically, control duty correction on the WG side is performed using the supercharging pressure as shown in FIG. In other words, when the boost pressure increases due to sudden acceleration, the control duty on the WG side is reduced when the predetermined boost pressure P0 is exceeded.
Lose weight by 50%.

However, if the P0 level is set low (e.g. 375mmHg) to prevent overshoot,
Since the boost pressure will decrease thereafter, the reduction in P0 slice level will only occur for 0.3 seconds after the boost pressure reaches P0. After 0.3 seconds, P1 to P3 (>P0)
Normal fail-safe processing is performed to gradually reduce and correct the control duty on the WG side using the slice level as the slice level.

In other words, when the VN has a delay in control response due to changes over time and it becomes difficult to control the boost pressure normally using the boost pressure control on the VN side, the system can be used to protect the engine and before performing a fuel cut as a last resort. By opening the WG in a corrective manner, the supercharging pressure is controlled to the target value, and the deterioration in drivability that occurs when the fuel is cut is prevented.

Also, in consideration of the case where the WG does not open, if the situation continues to exceed P4, a fuel cut request flag is set so that the engine control system performs a fuel cut as a last resort.

The control duty on the WG and VN side finally determined in this way is ONDUTY1, which will be described later.
After being transferred to ONDUTY 0, they are output to the solenoid valves 77 and 57 shown in FIG. 3, respectively, via the output interface. Note that overshoot countermeasures and failsafe measures are taken by correcting ONDUTY1 and ONDUTY0.

Next, the feedback control P2FBCONT performed in step 211 of FIG. 5A will be explained using the flowchart of FIG. 6.

Here, we will determine the start conditions for integral control of VN feedback control, determine the conditions for switching feedback control from the VN side to the WG side, initialize the feedback control variables, and determine the conditions for switching feedback control from the WG side to the VN side. In addition to determining the amount of feedback correction and learning amount, the final control amount is calculated.
Store in ONDUTY0 and ONDUTY1.

To explain in sequence, in step 0, in order to avoid abnormal combustion when the intake air flow rate increases, processing is performed to reduce the control target value P2ADAPT.

For example, as shown in FIG. 11A, a one-dimensional table is stored in a memory (ROM), and when the intake air flow rate QS exceeds a predetermined intake air flow rate QSPDOWN0, the control target value is gradually decreased.

In step 101, a flag FP2FBVNWG indicating whether the control area is on the VN or WG side is checked, and if it is "1", it is determined that feedback control is being performed on the WG side, and the step is started.
Proceed to 111. If it is "0", the process proceeds to step 102 and thereafter, where the operating range in which feedback control is to be performed is determined and the amount of learning is calculated.

First, in step 102, it is checked whether the actual supercharging pressure P2 is smaller than the range judgment supercharging pressure P2JUDGE (230 mmHg) that determines the operating range in which feedback control is performed, and if it is smaller, the operating range is not determined. Proceed to step 111. This is to prevent the feedback control from switching to the WG side before entering the overboost control after a sudden acceleration determination, which will be described later, is performed.

In other words, in overboost control, sudden acceleration is determined by comparing the acceleration time from 100 mmHg to 200 mmHg with the determination standard TJUDGE, and if the acceleration time is smaller than TJUDGE, it is determined that there is sudden acceleration. However, if the supercharging pressure P2 is
If the above driving range is to be determined even when it is smaller than P2JUDGE, apart from the sudden acceleration determination,
In order to determine which side of the VN or WG should perform feedback control, the intake air flow rate QS and the feedback control area judgment air flow rate as described later are used.
A comparison with QSVNTWG will be made.

Therefore, when sudden acceleration is determined and overboost control is performed to improve responsiveness during sudden acceleration, if the intake airflow becomes larger than QSVNTWG, it is determined that the intake airflow is in the WG side control region.
Feedback control is performed regardless of sudden acceleration judgment.
The VN side will switch to the WG side, making it impossible to perform overboost control, so to prevent this, the supercharging pressure P2
is smaller than JUDGE, the above judgment is not performed.

In step 103, the air flow rate for determining the feedback control area during normal operation is entered in the register ACC.
Store QSVNTWG. The condition for switching feedback control from the VN side to the WG side is when this area determination air flow rate QSVNTWG is exceeded.
In FIG. 15, this is the air amount line A.

That is, in the figure, the area to the left of line A is
The control area on the VN side is the control area on the WG side, and the right side is the control area on the WG side.

In step 104, it is checked whether or not there is sudden acceleration. If the flag FACCEL is "1", it is determined that there is a sudden acceleration and the process proceeds to step 105; if it is not determined that there is a sudden acceleration, the process proceeds to step 107. This flag FACCEL becomes “1” when sudden acceleration is determined.
This is a sudden acceleration determination flag that is set in the acceleration determination process, which will be explained later in the acceleration determination process.

In step 105, it is checked whether overboost control has ended, and if it is determined that overboost control is in progress, step 105 is performed.
The process proceeds to step 106, and if it is determined that the overboost control has ended, the process proceeds to step 107.

In step 106, the area judgment air flow rate QSVNTWGX (>
QSVNTWG) to ACC.

This area determination air flow rate QSVNTWGX is the first
This is the air amount line B shown in FIG. That is, since the control region on the VN side expands during overboost control, the region determination air flow rate is increased from line A to line B accordingly.

In step 107, the area determination air flow rate stored in the ACC is compared with the actual intake air flow rate QS.
If QS is larger than ACC, it is determined that it is not in the VN side control area, and in step 108, a flag is flagged to indicate whether it is in the VN or WG side control area.
Set FP2FBVNWG to “1”.

As a result, FP2FBVNWG=1 is now
This means that the control area on the VN side has been switched to the WG side, and in step 109, a timer is started to start learning control on the WG side, and
Calculate learning amount on VN side in step 110
Perform ACCLEARNVN. This learning amount calculation will be described later.

In step 111, the flag FP2FBVNWG is checked, and if it is "0", the process goes to 113, and if it is "1", the learning amount calculation ACCLEARNWG on the WG side is checked to 112.
Do it with This learning amount calculation will also be described later.

In this way, it is possible to determine the operating range in which feedback control is performed as shown in FIG.
The amount of learning on the WG side will be calculated.

Next, from step 113 onward, feedback correction amounts are calculated for each of the VN and WG sides. Here, proportional-integral-differential control will be described, and the proportional, integral, and differential components calculated from the deviation will be abbreviated as P, I, and D, respectively.

First, in step 113, the P portion on the VN side is calculated, added to BASEDUTY0 obtained earlier, and the result of the addition is stored in the memory M2. This P calculation is used to ensure control safety and basic control duty.
Taking into account the case where BASEDUTY0 is off, use the following calculation.

That is, the P portion on the VN side is KPVN x (ERROR) ² . Here, ERPOR is the deviation between the target boost pressure and the actual boost pressure (ERROR=P2ADAPT−P2),
KPVN is the operational gain.

In step 114, P on the WG side is similarly calculated and added to the aforementioned BASEDUTY1, and the added result is stored in the memory M2+2. however
The P portion on the WG side is KWG×ERROR, and KPWG is the operational gain.

In addition, in Figure 14, the P portion on the VN side is indicated by a broken line, and the WG
The P portion on the side is shown by a solid line.

The P component of the feedback control obtained in this way is always added, but since the integral-differential control is performed at a predetermined boost pressure or higher, steps 115 to
In step 118, it is determined whether integral-differential control is to be performed.
This is the main processing of this invention.

First, in step 115, the actual boost pressure P2 is stored in the register ACC, and in step 116, it is checked whether the target boost pressure P2ADART is 375 mmHg.

Step if P2ADAPT is 375mmHg
Proceed to 1118, but if P2ADAPT is less than 375mmHg, set P2DOWNVALUE in step 17.
Add to ACC. This usually means that the boost pressure is P2MIN
(320mmHg), next step 118
This is to determine that integral differentiation is possible in step 100, but if the control target value is lowered due to a high air flow rate in step 100, it is determined that control is possible from a lower boost pressure.

In other words, in the low and medium air flow range where the control target value is 375 mmHg, the actual boost pressure and the judged boost pressure P2MIN
(320mmHg) to determine the control region where integral-derivative control is performed, but in the high air flow region where the control target value falls below 375mmHg, the
It is preferable to also make P2MIN small to ensure a control region for performing integral-differential control.

Therefore, P2 stored in register ACC,
All you have to do is to compare the value obtained by subtracting a predetermined value from P2MIN, but this can be done by adding the above predetermined value to P2 in advance, and then comparing this added value with the predetermined value.
The same results can be obtained when comparing with P2MIN. The predetermined value in this case is
P2DOWNVALUE, and P2DOWNVALUE may be a constant value or may be a value that changes according to QS.

In step 118, it is checked whether ACC is greater than or equal to P2MIN, and if it is greater than or equal to P2MIN, it is determined that integral-differential control is possible and the process is continued.
Proceed to 127.

That is, P2MIN is set as a predetermined boost pressure lower than the target boost pressure, and when P2MIN is exceeded, it is given as a condition for starting integral control of VN feedback control.

If it is not determined that control is possible, step
Check whether QS is less than the predetermined air flow rate QSWGAREA in step 119, and if it is smaller, proceed to step 120.
In step 121, various control sequence flags are reset and various feedback variables are initialized, and in step 121, the learning amounts on both the VN and WG sides are rewritten.

In other words, when the boost pressure is smaller than P2MIN and the air flow rate is smaller than QSWGAREA, the feedback control variables are initialized and the WG side
Given as a condition for switching control to the VN side.

Therefore, if it is larger than QSWGAREA,
If the boost pressure drops instantaneously in the high air flow rate region, the process proceeds to step 122 in order to prevent the flag from being reset or the variables from being initialized.

In other words, if the accelerator pedal is temporarily released during full throttle acceleration in the high air flow range, the boost pressure may decrease faster than the intake air flow rate, and in this case the air flow rate remains high. is,
Even though it is in the WG side control range, the boost pressure is above
The effect is lower than P2MIN.

Therefore, if we decide to reset the flags and initialize the variables for feedback in this case as well, the accumulated value ERRORIWG of the deviation ERROR up to the previous time on the WG side will disappear, and the control amount on the WG side will be small. If there are variations in parts or the like, this may lead to a control error, so to prevent this, the above-mentioned flags are not reset.

In step 122, the values stored in memories M2 and M2+2 (the result of adding various correction amounts to the basic control duty) are set to ONDUTY0 and ONDUTY.
Move to 1. Note that for this transfer, an upper limit value and a lower limit value are set, and the respective values on the VN and WG sides are limited between the upper limit value and the lower limit value.

In step 123, QS determines the air flow rate.
It is checked whether it is smaller than QSDUTYCUT, and if it is smaller, the control duties ONDUTY0 and ONDUTY1 are set to the minimum value in step 124.
This process is performed to increase durability by not moving the control solenoid valves 57, 77 at low air flow rates such as during idle.

In step 125, error prevention processing for acceleration determination is performed. The contents of this process will be explained in the acceleration determination process described later. After this, the process advances to step 212 of the WGCONTROL process shown in FIG. 5A.

Next, a case where it is determined in step 118 that the integral-derivative control is in the controllable region and the process proceeds to step 127 will be described.

From step 127 onwards, the judgment result (step
101-106)),
Performs calculations on the VN and WG sides.

First, in step 127, the flag
Check whether FP2FBVNWG is “1”,
If it is "1", in step 128, the current deviation ERROR is added to the accumulated value ERRORIWG of the previous deviation ERROR on the WG side. If “0”, step
Proceed to step 129, and add the current deviation ERROR to the accumulated value ERRORIVN of the previous deviation ERROR on the VN side.

In step 130, it is checked whether overboost control has started, and if it is determined that it has started, in step 131, a correction amount VNCOEFI during overboost control is added to ERRORIVN. This is to add the feedforward control amount corresponding to the increase in the control target value during overboost control.

If overboost control has not started, proceed to step 132, check FP2FBVNWG,
If it is “1”, it is the control area on the WG side, so proceed to step 133, and calculate the integrated value of the deviation ERROR on the VN side.
Subtract the specified value from ERRORIVN.

That is, after the feedback control is switched from the VN side to the WG side, the control amount on the VN side is gradually decreased from the control amount immediately before switching. Even after the feedback control is switched to the WG side, if the control amount on the VN side is maintained at the control amount immediately before switching, the flow velocity in the exhaust introduction passage 40 shown in FIG. 4 increases as the exhaust gas flow rate increases. As a result, the pressure decreases, and this pressure decrease causes the movable tongue portion 45 to rotate in a direction to close the exhaust gas introduction passage 40, thereby reducing the capacity of the turbocharger.

In contrast, the integrated value of the deviation ERROR on the VN side
When the predetermined value is subtracted from ERRORIVN, the movable tongue 4
5 is rotated in the direction to open the exhaust introduction passage 40 and is fully opened, so that sufficient exhaust capacity can be secured even when the WG side control is entered, and the performance of the turbocharger can be maximized. .

On the other hand, if FP2FBVNWG is "0", proceed to step 134, and convert the I part on the VN side to KIVN×
Find it by calculating ERRORIVN, and add this to M2 as described above.
Add to. Here, KIVN is the operational integral gain. At the same time, this I
The minutes are stored in VNLEARN as the learning amount on the VN side this time.

In step 135, the I portion on the WG side is KIWG ×
It is obtained by calculating ERRORIWG, and this is calculated using the above
Add to M2+2. Here, KIWG is the operational integral gain. At the same time, for learning control, this I minute is used as the learning amount on the WG side this time.
Save to WGLEARN.

In step 136, D is calculated and the result is stored in memory M1. The calculation for this D is KD
Calculate by ×(ERROR1−ERROR). here
KD is the operational differential gain.

Specifically, FP2FBVNWG checks which side of VN or WG is being controlled, and if it is in the VN side control area, the VN side gain KDVN is changed.
If it is in the WG side control region, the WG side gain KDWG
Select and calculate. In addition, ERROR1 is the previous
It is ERROR.

In step 137, when FP2FBVNWG is "1", proceed to step 138, add D on the WG side to the WG side, store the added result in M2+2,
If it is "0", the process advances to step 139, where the D portion on the VN side is added to the VN side, and the added result is stored in M2.

In step 140, the current deviation ERROR (=
P2ADAPT−P2) is stored in ERROR1.

In steps 141 and 142, the values stored in the memories M2 and M2+2 (results of adding various correction amounts to the basic control duty) are transferred to ONDUTY0 and ONDUTY1 as the final control duty. Note that for this transfer, an upper limit value and a lower limit value are set, and the values on the VN and WG sides are limited between the upper limit value and the lower limit value. The rest is shown in Figure 5A.
Proceed to step 212 of VNWGCONTROL processing.

Next, overboost control for improving acceleration performance by temporarily increasing boost pressure during rapid acceleration will be further explained. Basically, overboost control is realized by correcting the aforementioned feedforward control amount and increasing the control target value.

Figure 5B is a flowchart of the process BOOSTCNTR that sets and resets various flags for overboost, and Figure 7A is the sudden acceleration determination process ACCELJUDGE.
The flowchart is shown below.

First, the determination of sudden acceleration will be explained step by step based on FIG. 7A. This process is executed once every 10 ms, in addition to the control calculation process described earlier.

In step 300, boost pressure is stored in P2.
Then, in step 301, it is checked whether P2 has exceeded 100 mmHg. If not, in step 302, flags for various control sequences are reset and various variables are initialized. If it is 100 mmHg or more, proceed to step 303, and if it exceeds it for the first time, proceed to step 304 to start a timer for measuring acceleration time.

Then, in step 305, a time serving as a determination standard is calculated based on the engine rotation speed at 100 mmHg, gear position, etc., and this is stored in TJUDGE.

This judgment standard is the judgment line shown in Figure 13B, that is, the judgment line given by the engine rotation speed (rpm) (×10ms) at 156250/100mmHg, and the acceleration time τ, which will be described later, is below this judgment line. If it is in the side area,
It is determined that the acceleration is sudden. Note that the numbers in the figure indicate the gear positions from 1st to 4th gear, and up to 3rd gear there is no problem as it falls below the judgment line, but in 4th gear, the acceleration time τ (supercharging The time required for the pressure to go from 100mmHg to 200mmHg) exceeds the judgment line and is distributed in the area surrounded by the broken line in the figure.

Therefore, in the 4th speed low rotation range, it is necessary to move the judgment line beyond this area, and the value obtained by adding a predetermined value to the value of the judgment line is used as the judgment standard. For these reasons, the gear position is also taken into consideration as a criterion.

Returning to FIG. 7A, if the temperature exceeds 100 mmHg for the second time or later in step 303, proceed to step 307 and proceed to step 2.
Check if exceeds 200mmHg and set 200
If it is less than mmHg, sudden acceleration will not be judged.

If it exceeds 200 mmHg, the timer value reset in step 304, that is, the acceleration time τ shown in FIG.
mmHg) is smaller than the criterion TJUDGE determined in step 305,
If it is smaller, the process proceeds to step 309, where it is determined that there is a sudden acceleration and FACCEL is set to "1". After that, the process returns to engine control.

In this way, the boost pressure required for control is input and the sudden acceleration state is determined.
It is used in each process of BOOSTCNTR in FIG. 5B, which will be explained next.

Next, to explain the process BOOSTCNTR for optimally performing overboost control using Figure 5B, this BOOSTCNTR is VNWGCONTROL
Execute once before executing , and pass various information necessary for overboost control.

Below, I will explain step by step.
214 checks whether overboost control has ended. This is explained in step 236 below.
This is done by checking the result of the process to end the overboost control performed in steps 239 to 239.

If it is determined that control has ended, step
Proceeding to step 241, the control target value is gradually lowered (at the same time, the feedforward control amount during overboost control is also gradually reduced).

If the control has not been completed, proceed to step 215.
The sudden acceleration determination flag FACCEL, which is set or reset in the sudden acceleration determination process described above, is checked. If it is "0", the process is terminated; if it is "1", sudden acceleration has been determined, so proceed to step 216. Go on,
Check if overboost control is allowed.

This is because whether or not overboost control is performed differs depending on the engine type and car model, so by having this information in memory (ROM), for example, you can use the same program to specify different specifications with or without overboost control. It is intended to correspond to the following.

If overboost control is permitted, proceed to step 217 and check whether the engine water temperature is below 100°C. Overboost control is not performed when the temperature is over 100℃, as abnormal combustion is likely to occur. If the temperature is less than 100°C, proceed to step 218, and set the feed forward correction start flag FP2WG on the WG side to "1".

In step 219, it is checked whether the supercharging pressure has exceeded 250 mmHg, and if it has not, the process is terminated. If it is exceeded, proceed to step 221. If it exceeds 250mmHg for the first time, take steps.
Proceeding to step 222, the sudden acceleration judgment error prevention timer is started, and the feed forward correction start flag FP2VN on the VN side is set to "1".

The measurement time of this erroneous judgment prevention timer is checked in the sudden acceleration judgment error prevention process in step 125 of Fig. 6 mentioned above, and if 3 seconds or more elapse from exceeding 250 mmHg to 320 mmHg, it is considered that sudden acceleration has occurred. Without making a judgment, set the sudden acceleration judgment flag FACCEL and the feed forward correction start flag FP2VN on the VN side to “1”
Set to .

This is because when accelerating from 1/4 throttle valve opening in 2nd gear as shown in Fig. 17, the time τ used for sudden acceleration judgment is short, and although it is judged to be sudden acceleration, the acceleration time is short. This is to prevent drivability from worsening due to sudden changes in boost pressure caused by entering overboost control after acceleration is completed.

That is, if the time T0 measured by the misjudgment prevention timer from 250 mmHg to 320 mmHg is T0≧3, it is not considered to be a sudden acceleration.

Next, in step 221, if the pressure exceeds 250 mmHg for the second time or later, the process proceeds to step 223, and the boost pressure P2 is
Check whether it exceeds 345mmHg. If it exceeds 345 mmHg, proceed to step 225 and check whether it exceeds 345 mmHg for the first time.

If it is exceeded for the first time, the process proceeds to step 226, starts a timing timer that measures the timing to increase the control target value, and ends the process.

If the temperature exceeds 345 mmHg for the second time or later in step 225, the process advances to step 228, and the timing timer started in step 226 is set for a predetermined period of time (0.3 seconds).
Check whether the time has elapsed, and if the time has elapsed, proceed to step 229.

If the predetermined time has elapsed for the first time, the process proceeds to step 230, where the overboost control amount is determined in accordance with the engine water temperature, and the control target value is increased.

That is, using a one-dimensional table according to the water temperature as shown in Fig. 11B, the optimum overboost control amount is given by increasing a predetermined amount that decreases as the water temperature increases from the control target value of 425 mmHg during overboost control. .

Next, in the case of proceeding from steps 228 and 229 to step 232 and subsequent steps, the overboost control termination condition is checked in steps 232 and subsequent steps. In other words, in steps 232 and 234, the boost pressure is 375mmHg.
In order to measure the elapsed time since the time when 375 mmHg was exceeded for the first time in step 234, the process proceeds to step 235 and a timer for measuring overboost control time is activated.

If it exceeds 375 mmHg for the second time or later in step 234, the process proceeds to step 236, where it is checked whether the control time measurement timer activated in step 235 has exceeded a predetermined time.

If it exceeds it, proceed to step 239 and end the overboost control. If it has not been exceeded, proceed to step 237, check the notsking level,
If it is large, overboost control is terminated to prevent knocking.

If it is smaller, proceed to step 238 and check whether the intake air flow rate QS is larger than the judgment air amount QSBOOSTCUT that cuts overboost control. If it is larger, proceed to step 239 to prevent abnormal combustion from occurring and end overboost control. let

In this way, the BOOSTCNTR process processes various information for overboost control.

Next, learning control for correcting deviations in feedforward control amounts on the VN and WG sides will be explained.

First, on the VN side, the timing for calculating the learning amount is step 110 in Figure 6.
This is when feedback control was switched from the VN side to the WG side.

The amount of learning is determined by VNLEARN in step 134 of the same figure.
Let it be the I minute stored in . This means that the steady-state deviation when the boost pressure is controlled on the VN side is added to the feedforward control amount in advance from the next control.

Here, the actual learning amount calculation will be explained based on FIG. 8.

First, in step 400, it is checked by FACCEL whether overboost control is being performed.

Learning amount calculation is of course possible even in engines that do not perform overboost control, but in engines that perform overboost control,
Since the control area on the VN side expands in the overboost control area, the value of I is large. Since control accuracy can be improved by controlling with this large value, in this embodiment, the learning amount calculation is performed immediately after overboost control is performed.

That is, in an acceleration situation where overboost control is not performed, the learning amount is not calculated. If overboost control is performed, proceed to step 401.
Steady-state deviation found in step 134 of Figure 6
Subtract the correction amount during overboost control (15% in terms of control duty) from VNLEARN, and use the reduced result as VNLEARN again. This is because the basic control duty is optimally applied when not in overboost control.

In step 402, this VNLEARN and
Store the value plus LEARNVN in VNLEARNVALUE. Here, LEARNVN is the previous learning result, and this value LEARNVN and the current learning result
By adding VNLEARN, the learning amount is made to converge to the optimal value.

The latest learning results memorized in this way
VNLEARNVALUE is determined in step 121 of FIG.
By updating when the feedback control reset condition where QS becomes smaller than QSWGAREA is satisfied, it will be reflected in the next control.

In this example, the update timing is set to be when two conditions are satisfied, but it may be any timing as long as the condition that the pressure is at least lower than the predetermined boost pressure is satisfied.

Next, learning control on the WG side will be explained. The timing for calculating the amount of learning is step 112 in FIG. 6, which is 1.2 seconds after the feedback control is switched to the WG side.

The amount of learning is I stored in WGLEARN in step 135. This means that the steady-state deviation when the boost pressure is controlled on the WG side is added to the feedforward control amount in advance from the next control.

Here, the actual learning amount calculation will be explained based on FIG. 9.

First, in step 404, it is checked whether the measured value of the learning control start timer WGLEARNTIMER on the WG side, which was activated when the feedback control on the WG side was switched at step 109 in FIG. 6, is 1.2 seconds or more. do.

If the time is less than 1.2 seconds, no learning amount calculation is performed. If more than 1.2 seconds have passed, step 405
Then, similarly to the VN side, the current steady-state deviation WGLEARN obtained in step 135 of FIG. 6 and the previous learning amount LEARNWG are added and stored in WGLEARNVALUE.

This latest learned value is updated at the same timing as on the VN side, that is, at step 121 in FIG.

In this way, the feedforward control amount is corrected by calculating and updating the learning amount at optimal timings on both the VN and WG sides.

It should be noted that the various time measurement timers used in the above explanation are realized by a configuration in which the timers are incremented by 1 at fixed time intervals (10 ms) by TIMER processing, as shown in FIG. 7B.

〔Effect of the invention〕

As explained above, the turbocharger boost pressure control device according to the present invention performs feedback control on either the variable displacement means or the exhaust bypass valve depending on the target boost pressure, and also controls with either of them. Even when the engine is running, the region where integral control is started is determined and controlled according to the target boost pressure, so there is no large boost pressure overshoot in all operating regions and all acceleration patterns. This improves the durability of the engine, and also prevents the supercharging pressure from hunting due to control switching, making it possible to control it with good drivability.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram showing the configuration of the present invention. Figure 2A is a flowchart that extracts the main parts of the flowchart of this embodiment, Figure 2B is a characteristic diagram showing the relationship between target boost pressure and intake air amount, and Figure 2C is
FIG. 3 is a characteristic diagram showing basic control amounts of VN and WG. FIG. 3 is a schematic diagram of the mechanical configuration of an embodiment of the present invention, and FIG. 4 is a sectional view of the scroll portion of the turbocharger. 5A, 5B, 6, 7A, 7B, 8, and 9 are flowcharts showing the operation of this embodiment. Figures 10A and 10B are characteristic diagrams showing the basic control duty of VN and WG, respectively, and Figure 10C is the intake air amount QS.
FIG. 3 is a table showing the relationship between basic control duty and basic control duty.
Fig. 11A is a characteristic diagram showing the control target value for intake air amount QS, Fig. 11B is a characteristic diagram showing the decrease in overboost control amount with respect to engine water temperature, and Fig. 12 explains overshoot countermeasures and failsafe. Figure 13A is a characteristic diagram showing the rate of decrease in control duty with respect to boost pressure to
Figure 13B is a characteristic diagram that explains the relationship between engine speed and τ at 100 mmHg, and Figure 14 is a characteristic diagram that explains the relationship between ERROR and P (correction amount). , Figure 15 shows the intake air amount QS
Fig. 16 is a characteristic diagram explaining the respective control areas on the VN and WG sides, Fig. 16 is a supercharging characteristic diagram explaining overshoot during sudden acceleration, and Fig. 17 is a supercharging characteristic diagram explaining error prevention in sudden acceleration judgment. FIG.
FIGS. 18 and 19 are diagrams for explaining the effects of this embodiment. 1... Engine, 2... Operating state detection means, 3
...Target boost pressure setting means, 4...Supercharging pressure detection means, 5...Difference calculation means, 6...Feedback region discrimination means, 7...First control amount calculation means, 8
. . . second control amount calculation means, 9 . . . first control means, 10 . . . second control means, 11 . Intake pipe, 23... Intake manifold, 24... Exhaust manifold, 25... Exhaust pipe, 26... Bypass passage, 30... Crank angle sensor, 31... Air flow meter, 32... Throttle valve, 33... Supply pressure sensor, 35... Compressor, 37... Turbine, 38... Turbine chamber,
39...Scroll, 40...Exhaust introduction passage, 4
5... Movable tongue portion, 50... Actuator, 57
... Solenoid valve, 60 ... Exhaust bypass valve, 70 ...
Actuator, 77... Solenoid valve, 80... Control unit.

Claims (1)

[Scope of Claims] 1. Capacity variable means for varying the exhaust turbine capacity of the turbocharger and an exhaust bypass valve that bypasses part of the exhaust gas passing through the exhaust turbine from upstream to downstream, thereby adjusting engine overload according to operating conditions. A boost pressure control device for a turbocharger that controls boost pressure includes an operating state detection means for detecting an engine operating state, and a target supercharging pressure according to the engine operating state detected by the operating state detection means. A target boost pressure setting means to set a boost pressure, a boost pressure detection means to detect the actual engine boost pressure, and a deviation between the boost pressure detected by the boost pressure detection means and the target boost pressure. A deviation calculating means, a detection result by the operating state detecting means, and a supercharging pressure detected by the supercharging pressure detecting means, determine an operating region in which feedback control is to be performed, and perform feedback control on either the capacity variable means or the exhaust bypass valve. a feedback control region determining means for selecting whether or not to perform the control; and controlling the exhaust turbine capacity variable means and the exhaust bypass valve in accordance with parameters representing the operating state including at least the integrated value of the deviation calculated by the deviation calculation means. first and second control amount calculation means for calculating the amount; and a first control amount calculation means for driving and controlling the capacity variable means and the exhaust bypass valve according to the control amount calculated by the first and second control amount calculation means. A supercharging pressure control device for a turbocharger, comprising: a second control means; and a discriminating means for determining a region in which integral control during the feedback control is started in accordance with the target supercharging pressure.